WO2018193909A1 - Internal combustion engine ignition system - Google Patents

Internal combustion engine ignition system Download PDF

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Publication number
WO2018193909A1
WO2018193909A1 PCT/JP2018/015045 JP2018015045W WO2018193909A1 WO 2018193909 A1 WO2018193909 A1 WO 2018193909A1 JP 2018015045 W JP2018015045 W JP 2018015045W WO 2018193909 A1 WO2018193909 A1 WO 2018193909A1
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WO
WIPO (PCT)
Prior art keywords
switching element
winding
ignition
current
discharge
Prior art date
Application number
PCT/JP2018/015045
Other languages
French (fr)
Japanese (ja)
Inventor
貴士 大野
Original Assignee
株式会社デンソー
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2018051031A external-priority patent/JP2018178997A/en
Application filed by 株式会社デンソー filed Critical 株式会社デンソー
Priority to CN201880025906.5A priority Critical patent/CN110537016B/en
Priority to KR1020197029054A priority patent/KR102412744B1/en
Priority to EP18787553.9A priority patent/EP3613979A4/en
Publication of WO2018193909A1 publication Critical patent/WO2018193909A1/en
Priority to US16/656,923 priority patent/US10859057B2/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P3/00—Other installations

Definitions

  • the present disclosure relates to an ignition system used for an internal combustion engine.
  • an intermediate tap is provided in the middle of the winding of the primary coil, and after the main ignition is started on the ignition plug, energy is supplied to the intermediate tap. Electrical energy is sequentially input from the input power source. As a result, electric energy is supplied only to the winding from the intermediate tap to one end of the primary coil, and accordingly, a secondary current in the same direction as the secondary current caused by the main ignition is sequentially added to the secondary coil and flows. Thus, spark discharge is continuously generated in the spark plug.
  • the winding from the intermediate tap to one end of the primary coil is referred to as a second winding
  • the winding from the intermediate tap to the other end of the primary coil is referred to as a first winding.
  • a secondary voltage having a magnitude capable of continuously generating spark discharge in the spark plug without using a booster circuit is provided. It can be generated in the secondary coil.
  • Patent Document 1 is provided with an energy input switching element for turning on and off an energy input line for supplying electric energy to an intermediate tap of a primary coil. Each time the energy input switching element is turned ON, a primary current is additionally supplied to the second winding via the intermediate tap. On the other hand, the energy input is stopped by turning off the energy input switching element. While repeating this control, the secondary current is maintained at a predetermined value to improve the ignitability.
  • the disclosing persons have a relatively large decrease in the primary current when the switching element for energy input is turned off, and the secondary current is rapidly decreased to easily maintain the secondary current at a predetermined value. I found something not.
  • the present disclosure has been made to solve the above-described problems, and a main purpose thereof is to provide an internal combustion engine ignition system capable of suppressing a sudden decrease in secondary current during a discharge maintenance control period. It is to provide.
  • a first disclosure is an ignition system for an internal combustion engine, and includes an ignition plug that generates a spark discharge for igniting a combustible air-fuel mixture in a combustion chamber of the internal combustion engine, a primary coil, and a secondary coil.
  • An ignition tap that applies a voltage to the ignition plug by a secondary coil, a voltage application unit that applies a predetermined voltage to the primary coil, and an intermediate tap provided in the middle of the winding that forms the primary coil,
  • a third switching element that performs energization and interruption of a primary current flowing from the voltage application unit to the intermediate tap, and a first winding side that is a winding from the intermediate tap to one end of the windings that form the primary coil.
  • a first switching element connected between one end and the ground side, and one end on the second winding side, which is a winding from the intermediate tap to the other end of the windings forming the primary coil, and the ground side Connect between To the first winding by controlling the second switching element, the opening / closing state of the first switching element, the opening / closing state of the second switching element, and the opening / closing state of the third switching element, respectively.
  • Discharge generation control for energizing and interrupting the primary current flowing to generate the spark discharge in the spark plug, and energizing and interrupting the primary current flowing to the second winding to cause the spark generated in the spark plug
  • An ignition control circuit for performing discharge maintenance control for maintaining discharge, and a current return path for returning current flowing from the second winding to the second switching element.
  • the open / close state of the first switching element, the open / close state of the second switching element, and the open / close state of the third switching element are respectively controlled, and conduction and interruption of the primary current flowing to the first winding are controlled.
  • spark discharge is generated in the spark plug.
  • the open / close state of the first switching element, the open / close state of the second switching element, and the open / close state of the third switching element are controlled, respectively, and the conduction of the primary current flowing to the second winding is controlled. By performing the interruption, the spark discharge generated in the spark plug is maintained.
  • the primary current flowing through the second winding is interrupted without being interrupted.
  • the secondary current flowing through the plug may be greatly reduced stepwise.
  • the internal combustion engine ignition system is provided with a current return path, even if the first switching element and the third switching element are opened during the discharge maintenance control, As the primary current flows through the winding, it gradually attenuates. Thereby, it can suppress that the secondary current which flows into a spark plug becomes small in steps.
  • the first switching element is provided with a reverse diode, there is a current return path for the second winding 12C via the reverse diode and the first winding 12B. Under the influence of the voltage generated at 12B, the return current of the second winding 12C decreases, and the secondary current also decreases rapidly.
  • the current return path includes a first diode, a cathode side of the first diode is connected to the intermediate tap, and an anode side of the first diode is a ground side. It is connected to the.
  • the primary current flowing through the current return portion does not flow to the first winding, but flows directly to the second winding. Therefore, the primary current is not affected by the first winding. It becomes possible to control with high accuracy.
  • the ignition control circuit controls the second switching element to an open state, and then closes the first switching element and the third switching element. Controlling, and then controlling the first switching element to an open state, conducting and blocking the primary current flowing to the first winding, and controlling the first switching element to an open state, The second switching element and the third switching element are controlled to be closed, and then the third switching element is controlled to be opened, thereby conducting and circulating the primary current flowing to the second winding. .
  • the conduction and interruption of the primary current flowing through the first winding is controlled by opening the second switching element and controlling the third switching element to the closed state. It can be implemented by switching. Also, the conduction and recirculation of the primary current flowing through the second winding is performed by controlling the first switching element to the open state and controlling the second switching element to the closed state, and then switching the third switching element. can do.
  • the ignition control circuit controls the second switching element to an open state, and then closes the first switching element and the third switching element. Controlling, and then controlling the first switching element to an open state, conducting and blocking the primary current flowing to the first winding, and controlling the first switching element to an open state, Controlling the second switching element and the third switching element to a closed state, and then controlling the second switching element to an open state allows conduction and interruption of the primary current flowing to the second winding. .
  • a fifth disclosure is an ignition system for an internal combustion engine, and includes an ignition plug that generates a spark discharge for igniting a combustible mixture in a combustion chamber of the internal combustion engine, a primary coil, and a secondary coil.
  • An ignition coil that applies a voltage to the ignition plug by a secondary coil, an intermediate tap provided in the middle of the winding that forms the primary coil, a voltage application unit that applies a predetermined voltage to the intermediate tap, and Of the windings forming the primary coil, the first switching element connected between one end on the first winding side that is the winding from the intermediate tap to one end and the ground side, and the winding of the winding forming the primary coil
  • a second switching element connected between one end on the second winding side which is a winding from the intermediate tap to the other end and the ground side, an open / close state of the first switching element, and the second switching element
  • the open / close state of the first switching element and the open / close state of the second switching element are controlled, and the primary current flowing through the first winding is turned on and off, thereby sparking the spark plug. Generate a discharge. Further, in the discharge maintenance control, the open / close state of the first switching element and the open / close state of the second switching element are respectively controlled, and conduction and interruption of the primary current flowing to the second winding is performed, so that the spark plug The spark discharge that occurs is maintained. At this time, if there is no current return path, when the first switching element and the second switching element are opened during the discharge maintenance control, the primary current flowing through the second winding is interrupted without being interrupted.
  • the secondary current flowing through the plug may be greatly reduced stepwise.
  • the internal combustion engine ignition system is provided with a current return path, even if the first switching element and the second switching element are opened during the discharge maintenance control, The primary current flows through the winding while being attenuated. Thereby, it can suppress that the secondary current which flows into a spark plug becomes small in steps.
  • the current return path includes a second diode, and a cathode side of the second diode is connected to a current path between the voltage application unit and the intermediate tap.
  • the anode side of the second diode is connected to the current path between the second winding and the second switching element.
  • the primary current flowing through the current return portion does not flow to the first winding, but flows while being attenuated to the second winding. Therefore, the primary current is not affected by the first winding. It becomes possible to control the current with high accuracy.
  • the ignition control circuit controls the second switching element to an open state and controls the first switching element to a closed state as the discharge generation control. Then, by controlling the first switching element to the open state, the primary current flowing to the first winding is turned on and off, and the first switching element is controlled to the open state as the discharge maintenance control. Then, the second switching element is controlled to be closed, and then the second switching element is controlled to be opened, thereby conducting and refluxing the primary current flowing to the second winding.
  • the conduction and interruption of the primary current flowing through the first winding can be performed by switching the first switching element while controlling the second switching element to the open state. Further, conduction and recirculation of the primary current flowing through the second winding can be performed by switching the second switching element after controlling the first switching element to be in an open state.
  • the cathode side is connected to the second switching element, and the anode side is connected to an end opposite to the intermediate tap side.
  • a third diode is connected to the cathode side.
  • a current that flows from the second switching element to the voltage application unit through the second winding may be generated by performing the discharge start control. That is, when the magnetic flux generated by the cut-off current of the first winding is linked to the second winding, a voltage is generated at the end of the second winding and the current may be generated. In this case, the current flowing from the second switching element to the voltage application unit is canceled out, and the primary current is reduced by the amount canceled.
  • the current is generated by providing a third diode whose cathode side is connected to the second switching element and whose anode side is connected to the end of the second winding on the second switching element side. Even if the voltage is generated, it is possible to suppress the flow from the second switching element to the voltage application unit.
  • a cathode side is connected to the intermediate tap, and an anode side includes a third diode connected to the voltage application unit.
  • a tenth disclosure is an ignition system for an internal combustion engine, and includes an ignition plug that generates a spark discharge for igniting a combustible air-fuel mixture in a combustion chamber of the internal combustion engine, a primary coil, and a secondary coil.
  • An ignition coil that applies a voltage to the ignition plug by a secondary coil, an intermediate tap provided in the middle of the winding that forms the primary coil, a voltage application unit that applies a predetermined voltage to the intermediate tap, and A first switching element connected between one end on the first winding side that is a winding from the intermediate tap to one end of the winding forming the primary coil and the ground side, the intermediate tap, and the intermediate tap A third switching element connected between the second winding that is a winding from the other end to the other end, an open / close state of the first switching element, and an open / close state of the third switching element, respectively
  • An ignition control circuit for performing a discharge generation control for generating the spark discharge in the spark plug and a discharge maintaining control for maintaining the spark discharge generated in the spark plug; and the second winding And a current return path for returning the current flowing from the ground to the ground side.
  • the open / close state of the first switching element and the open / close state of the third switching element are controlled, and the primary current flowing through the first winding is turned on and off to spark the spark plug.
  • the discharge maintenance control the open / close state of the first switching element and the open / close state of the third switching element are controlled, and the conduction and blocking of the primary current flowing to the second winding are performed, so that the spark plug The spark discharge that occurs is maintained.
  • the primary current flowing through the second winding is interrupted without being interrupted. There is a concern that the secondary current flowing through the plug may be greatly reduced stepwise.
  • the internal combustion engine ignition system is provided with a current return path, even if the first switching element and the third switching element are opened during the discharge maintenance control, the inductance of the second winding Due to the component, the primary current flows from the current return path to the second winding while being gradually attenuated. Thereby, it can suppress that the secondary current which flows into a spark plug becomes small stepwise and rapidly.
  • An eleventh disclosure is the tenth disclosure, wherein the current return path includes a fourth diode, and a cathode side of the fourth diode is connected to a current path between the third switching element and the second winding.
  • the anode side of the fourth diode is connected to the ground side.
  • the primary current flowing through the current return portion does not flow to the first winding, but flows directly to the second winding, so that the primary current is not affected by the first winding. It does not decrease step by step, but gradually attenuates.
  • the primary current reaches a predetermined value, the current is supplied again from the third switching element.
  • the control to turn off the third switching element is repeated, so that the primary current can be accurately controlled to the predetermined value.
  • the cathode side is connected to the ground side, and the anode side is connected to an end of the second winding opposite to the intermediate tap side.
  • a third diode is provided.
  • a current that flows from the second winding to the voltage application unit via the third switching element may be generated by performing the discharge start control.
  • the magnetic flux generated by the breaking current of the first winding is canceled by the current flowing from the second switching element to the voltage application unit, and the primary current is reduced by the amount canceled.
  • the current is generated by providing a third diode whose cathode side is connected to the second switching element and whose anode side is connected to the end of the second winding on the second switching element side. Even if the voltage is generated by the discharge start control, it is possible to suppress the flow from the third switching element to the voltage application unit.
  • a cathode side is connected to an end portion of the intermediate tap side in the second winding, and an anode side is connected to the third switching element. Equipped with three diodes.
  • the third diode causes the third winding to It is possible to suppress the flow to the switching element.
  • the ignition control circuit controls the third switching element to an open state as the discharge generation control, and then switches the first switching element.
  • the primary current flowing to the first winding is turned on and off to start discharging, and as the discharge maintenance control, After controlling one switching element to an open state, controlling the third switching element to a state, and then controlling the third switching element to an open state, the primary current flowing to the second winding Conduct conduction and reflux.
  • the conduction and interruption of the primary current flowing through the first winding can be performed by switching the first switching element after controlling the third switching element to the open state. Further, conduction and recirculation of the primary current flowing through the second winding can be performed by switching the third switching element while controlling the first switching element to the open state.
  • the ignition control circuit controls the first switching element and the third switching element to be closed as the discharge generation control, and then By controlling the first switching element and the third switching element to an open state, the primary current flowing to the first winding and the second winding is turned on and off to start discharging, and the discharge is maintained.
  • the first switching element is controlled to be in an open state
  • the third switching element is controlled to be in a closed state
  • the third switching element is controlled to be in an open state. Conduction and recirculation of the primary current flowing to
  • the number of turns of the first winding is larger than the number of turns of the second winding.
  • the voltage for maintaining the discharge generated in the spark plug is lower than the voltage required for causing the spark plug to generate discharge during the discharge generation control.
  • the secondary voltage generated in the secondary coil when the primary voltage is applied to the second winding When a primary voltage is applied to one winding, it can be made lower than the secondary voltage generated in the secondary coil.
  • a seventeenth disclosure is the spark plug according to any one of the first to sixteenth disclosures, wherein a turn ratio, which is a value obtained by dividing the number of turns of the secondary coil by the number of turns of the second winding, is determined by the discharge generation control.
  • the discharge sustaining voltage which is a voltage necessary for maintaining the spark discharge generated in step 1, is configured to be larger than a voltage ratio that is a value obtained by dividing the discharge sustaining voltage by the voltage applied by the voltage applying unit.
  • the turn ratio is calculated by dividing the number of turns of the secondary coil by the number of turns of the second winding. That is, the smaller the number of turns of the secondary winding, the larger the turns ratio.
  • the voltage applied to the second winding during the discharge sustain control period is Can be set to be lower than the applied voltage.
  • the primary current can be repeatedly supplied from the voltage application unit to the secondary winding during the discharge maintenance control period, and the secondary current flows to the spark plug each time. As a result, the secondary current is generated in the spark plug. Spark discharge can be maintained.
  • the eighteenth disclosure includes a secondary current detection unit that detects a secondary current flowing through the spark plug, and the ignition control circuit performs the discharge maintenance control.
  • the third switching element When the absolute value of the secondary current detected by the secondary current detection unit becomes smaller than a first threshold during the implementation period, the third switching element is controlled to be closed, When the absolute value of the secondary current detected by the secondary current detection unit becomes larger than a second threshold value set larger than the first threshold value, the third switching element is controlled to be in an open state.
  • a nineteenth disclosure is the disclosure of the fourth or seventh disclosure, further comprising a secondary current detection unit that detects a secondary current flowing through the spark plug, wherein the ignition control circuit performs the discharge maintenance control.
  • the second switching element When the absolute value of the secondary current detected by the secondary current detection unit is smaller than a first threshold, the second switching element is controlled to be closed and detected by the secondary current detection unit When the absolute value of the secondary current is larger than a second threshold set larger than the first threshold, the second switching element is controlled to be in an open state.
  • both the control according to the eighteenth disclosure and the control according to the nineteenth disclosure can moderate the decrease in the secondary current when the primary current is interrupted.
  • the absolute value can be easily within the range from the first threshold value to the second threshold value. That is, by performing the feedback control with the secondary current described above, the secondary current can be accurately controlled within a desired range, and a sudden change in the secondary current can be reduced. It is possible to reduce the discharge spark blow-off phenomenon due to a sudden drop in current.
  • the first switching element, the second switching element, the third switching element, the ignition control circuit, and the current return unit are accommodated in a space in the ignition plug in which the ignition coil is accommodated. That is, the ignition system for the internal combustion engine can be accommodated in a space in the ignition plug in which the ignition coil is accommodated. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
  • a twenty-first disclosure is the disclosure according to any one of the fifth to seventh aspects, wherein the first switching element, the second switching element, the ignition control circuit, and the current return path are accommodated in the ignition coil. Is contained in a case.
  • the first switching element, the second switching element, the ignition control circuit, and the current return unit are accommodated in a space in the ignition plug in which the ignition coil is accommodated. That is, the ignition system for the internal combustion engine can be accommodated in a space in the ignition plug in which the ignition coil is accommodated. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
  • the first switching element, the third switching element, the ignition control circuit, and the current return path are accommodated in the ignition coil. Is contained in a case.
  • the first switching element, the third switching element, the ignition control circuit, and the current return unit are accommodated in a space in the ignition plug in which the ignition coil is accommodated. That is, the ignition system for the internal combustion engine can be accommodated in a space in the ignition plug in which the ignition coil is accommodated. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
  • a fifth diode is connected in antiparallel to the first switching element.
  • the present ignition system when the discharge maintenance control is performed in a state where there is no current return path, the primary current flowing to the second winding is connected in reverse parallel to the first switching element. The current flowing from the second winding to the second switching element through the five diodes and the first winding is returned. In this case, the current flowing back is affected by the first winding, so that the magnitude of the current is reduced, and the secondary current generated in the secondary coil is reduced accordingly. is there.
  • the present ignition system is suitable for a configuration in which the fifth diode is connected in antiparallel to the first switching element. It can be said that it is a composition.
  • the internal combustion engine is a multi-cylinder internal combustion engine
  • the ignition control circuit is provided in each cylinder of the internal combustion engine.
  • a control device for outputting a current control signal for controlling a current flowing through the secondary coil in the maintenance control; and a first common signal line and a second common signal line for transmitting the current control signal are connected to the control device.
  • Each signal line branched from the first common signal line is connected to the ignition control circuit of each cylinder of the first cylinder group, which is a group of cylinders in which ignition by the spark plug does not continue,
  • Each of the signal lines branched from the common signal line is a group of cylinders that are not continuously ignited by the spark plug and is a group of cylinders not included in the first cylinder group. It is connected to the control circuit.
  • the internal combustion engine is a multi-cylinder internal combustion engine (for example, an internal combustion engine having five or more cylinders)
  • the current control signal for controlling the current flowing in the secondary coil is made common to all the cylinders, There is a possibility that part of the control signal overlaps.
  • the control device outputs a current control signal for controlling the current flowing in the secondary coil in the discharge maintenance control.
  • a first common signal line and a second common signal line for transmitting a current control signal are connected to the control device.
  • Each signal line branched from the first common signal line is connected to the ignition control circuit of each cylinder of the first cylinder group, which is a group of cylinders that are not continuously ignited by the spark plug. For this reason, ignition of the cylinders of the first cylinder group is not continuous, and it is possible to suppress a part of the current control signal transmitted to the cylinders of the first cylinder group from overlapping.
  • each of the signal lines branched from the second common signal line is a group of cylinders that are not continuously ignited by the spark plug and is a group of cylinders not included in the first cylinder group. Connected to the control circuit. For this reason, ignition of the cylinders of the second cylinder group is not continuous, and it is possible to suppress a part of the current control signal transmitted to the cylinders of the second cylinder group from overlapping. Therefore, even if the internal combustion engine is a multi-cylinder internal combustion engine, the current flowing through the secondary coil can be controlled by the current control signal.
  • the ignition is performed in one cylinder included in the second cylinder group while the ignition is performed in succession in two cylinders included in the first cylinder group. Done.
  • FIG. 1 is a schematic configuration diagram of an ignition system according to the first embodiment.
  • FIG. 2 is a diagram showing the flow of the primary current when the discharge start control is started
  • FIG. 3 is a diagram showing the flow of the primary current when the discharge maintenance control is performed
  • FIG. 4 is a diagram showing fluctuations in the primary current and the secondary current when the discharge maintenance control is performed in an ignition system in which no current return path is provided
  • FIG. 5 is a diagram showing the flow of the primary current that circulates when the discharge maintenance control is performed
  • FIG. 6 is a diagram simply showing the content of controlling the secondary current to a desired range
  • FIG. 1 is a schematic configuration diagram of an ignition system according to the first embodiment.
  • FIG. 2 is a diagram showing the flow of the primary current when the discharge start control is started
  • FIG. 3 is a diagram showing the flow of the primary current when the discharge maintenance control is performed
  • FIG. 4 is a diagram showing fluctuations in the primary current and the secondary current when the discharge maintenance control is performed in an ignition system in which no current return
  • FIG. 7 is a time chart showing the operation of the discharge control according to the present embodiment.
  • FIG. 8 is a schematic configuration diagram showing the periphery of a case in which an ignition coil is housed in an internal combustion engine
  • FIG. 9 is a time chart showing an operation of discharge control according to another example.
  • FIG. 10 is a diagram showing another example of the installation location of the third diode applied to the configuration of FIG.
  • FIG. 11 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment.
  • FIG. 12 is a diagram showing the setting of the command value of the secondary current by the ignition signal and the energy input signal
  • FIG. 13 is a diagram showing the setting of the command value of the secondary current by the ignition signal and the energy input signal, FIG.
  • FIG. 14 is a diagram showing the setting of the command value of the secondary current by the ignition signal and the energy input signal
  • FIG. 15 is a time chart showing the operation of the discharge control according to another example shown in FIG.
  • FIG. 16 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment
  • FIG. 17 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment
  • FIG. 18 is a time chart showing an operation of discharge control according to another example shown in FIG.
  • FIG. 19 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment
  • FIG. 20 is a schematic configuration diagram of an ignition system according to the second embodiment.
  • FIG. 21 is a time chart showing the operation of the discharge control according to the second embodiment.
  • FIG. 21 is a time chart showing the operation of the discharge control according to the second embodiment.
  • FIG. 22 is a diagram showing another example of the installation location of the third diode applied to the configuration of the second embodiment
  • FIG. 23 is a schematic configuration diagram illustrating another example of the ignition system according to the second embodiment
  • FIG. 24 is a time chart showing the operation of discharge control according to another example shown in FIG.
  • FIG. 25 is a diagram showing an example of changing the installation location of the third diode in another example shown in FIG.
  • FIG. 26 is a schematic configuration diagram of an ignition system according to a third embodiment.
  • FIG. 27 is a time chart showing the operation of the discharge control according to the third embodiment.
  • FIG. 28 is a diagram showing another example of the installation location of the third diode applied to the third embodiment
  • FIG. 29 is a schematic configuration diagram illustrating another example of the ignition system according to the third embodiment, FIG.
  • FIG. 30 is a time chart showing an operation of discharge control according to another example shown in FIG.
  • FIG. 31 is a diagram comparing a secondary voltage generated by discharge generation control according to another example applied to the third embodiment and a secondary voltage generated by conventional discharge generation control
  • FIG. 32 is a schematic configuration diagram showing a connection between an engine ECU applied to a four-cylinder engine and each ignition control circuit
  • FIG. 33 is a time chart showing an ignition signal and an energy input signal of a comparative example
  • FIG. 34 is a schematic configuration diagram showing a connection between an engine ECU applied to a 6-cylinder engine and each ignition control circuit.
  • FIG. 35 is a time chart showing the ignition signal and the energy input signal of the embodiment shown in FIG.
  • FIG. 36 is a time chart showing the operation of discharge control based only on the ignition signal
  • FIG. 37 is a schematic configuration diagram of an ignition system that performs the discharge control of FIG.
  • the ignition system 10 is mounted on an internal combustion engine (hereinafter referred to as an engine) 60 (see FIG. 8).
  • the configuration of the ignition system 10 will be described with reference to FIG.
  • the ignition system 10 includes an ignition plug 20, an ignition coil 11, a third switching element 14, a first switching element 15, a second switching element 16, a power supply unit (corresponding to a voltage application unit) 17, an ignition control A circuit 30 is provided.
  • the ignition coil 11 includes a primary coil 12, a secondary coil 13, and an iron core 23.
  • An intermediate tap 12 ⁇ / b> A is provided in the middle of the winding forming the primary coil 12, and the intermediate tap 12 ⁇ / b> A is connected to the power supply unit 17 via the third switching element 14. Therefore, when the third switching element 14 is closed, a predetermined voltage is applied from the power supply unit 17 to the intermediate tap 12A.
  • one end on the first winding 12 ⁇ / b> B side which is a winding having a larger number of turns from the intermediate tap 12 ⁇ / b> A to one end among the windings forming the primary coil 12, is connected to the first switching element 15.
  • One end on the second winding 12 ⁇ / b> C side which is the winding having the smaller number of turns from the intermediate tap 12 ⁇ / b> A to one end among the windings forming the primary coil 12, is connected to the second switching element 16 via the third diode 19. Has been.
  • the third switching element 14 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and has a third control terminal 14G, a third power supply side terminal 14D, and a third ground side terminal 14S.
  • the third switching element 14 controls on / off of energization between the third power supply side terminal 14D and the third ground side terminal 14S based on the third control signal input to the third control terminal 14G. It is configured.
  • the third ground side terminal 14 ⁇ / b> S is connected to the intermediate tap 12 ⁇ / b> A
  • the third power supply side terminal 14 ⁇ / b> D is connected to the power supply unit 17.
  • the first switching element 15 is an IGBT (Insulated Gate Bipolar Transistor) that is a MOS gate structure transistor, and includes a first control terminal 15G, a first power supply side terminal 15C, and a first ground side terminal 15E. ing.
  • the first switching element 15 controls on / off of energization between the first power supply side terminal 15C and the first ground side terminal 15E based on the first control signal input to the first control terminal 15G. It is configured.
  • the first power supply side terminal 15C is connected to the first winding 12B.
  • the first ground side terminal 15E is grounded.
  • the second switching element 16 is a MOSFET, and has a second control terminal 16G, a second power supply side terminal 16D, and a second ground side terminal 16S.
  • the second switching element 16 controls on / off of energization between the second power supply side terminal 16D and the second ground side terminal 16S based on the second control signal input to the second control terminal 16G. It is configured.
  • the second power supply side terminal 16D is connected to the second winding 12C via the third diode 19, and the second ground side terminal 16S is grounded. Details of the third diode 19 will be described later.
  • the intermediate tap 12A is connected to the third switching element 14 and also to the current return path L1.
  • the current return path L1 includes a first diode 18.
  • the cathode side of the first diode 18 is connected to the intermediate tap 12A, and the anode side of the first diode 18 is grounded.
  • the first end of the secondary coil 13 is connected to a current detection path L2 through a spark prevention diode 21 (hereinafter referred to as a prevention diode) when the primary coil is energized.
  • the current detection path L2 is provided with a resistor 22 for detecting a secondary current.
  • the first end of the resistor 22 is connected to the first end of the secondary coil 13 via the prevention diode 21, and the second end of the resistor 22 is connected to the ground side.
  • the prevention diode 21 prevents a current from flowing from the ground side to the second end side of the secondary coil 13 through the resistor 22 that is generated when the first winding 12B is energized.
  • the ignition control circuit 30 is connected to the engine ECU so as to receive an ignition signal IGt output from an engine ECU (control device) (not shown).
  • the ignition signal IGt defines an optimal ignition timing and secondary current (discharge current) according to the state of gas in the combustion chamber of the engine 60 and the required output of the engine 60.
  • the ignition control circuit 30 also controls the third control terminal 14G, the first control terminal 15G, and the second control so as to control the opening / closing operation of the third switching element 14, the first switching element 15, and the second switching element 16. It is connected to the terminal 16G.
  • the ignition control circuit 30 Based on the ignition signal IGt received from the engine ECU, the ignition control circuit 30 includes a third control terminal 14G included in the third switching element 14, a first control terminal 15G included in the first switching element 15, and a second switching element. Drive signals IG1, IG2, and IG3 for performing open / close control on each of the second control terminals 16G of 16 are output.
  • a path (see FIG. 2) that flows from the power supply unit 17 to the first winding 12B is formed, and then the ignition plug is controlled by controlling the conduction and blocking of the primary current I1 that flows to the first winding 12B.
  • Discharge start control for causing a spark discharge at 20 is performed.
  • a path (see FIG. 3) that flows from the power supply unit 17 to the second winding 12C is formed, and then the conduction and interruption of the primary current I1 that flows to the second winding 12C is controlled.
  • the discharge maintenance control for maintaining the spark discharge generated in the spark plug 20 is performed.
  • the current detection path L2 and the ignition control circuit 30 correspond to a secondary current detection unit.
  • the second switching element 16 is always controlled to be in the open state. Then, by controlling the third switching element 14 and the first switching element 15 to be closed, a primary current I1 flows from the power supply unit 17 to the first winding 12B as shown in FIG. Then, the first switching element 15 is controlled to be in an open state after the first predetermined time has elapsed. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
  • the above discharge start control is performed in a state where the third diode 19 is not provided.
  • a current flowing from the second switching element 16 to the power supply unit 17 through the second winding 12C may be generated. That is, when the first winding 12B and the second winding 12C form a magnetic circuit, or the leakage magnetic flux is linked, the primary current I1 that flows in the first winding 12B by the first switching element 15 When the circuit is interrupted, a negative voltage is generated in the second winding 12 ⁇ / b> C, and a current may flow from the ground side to the power supply unit 17.
  • a current flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C is generated, the generated current and the primary current I1 flowing from the power supply unit 17 to the first winding 12B are mutually connected. By canceling out, the primary current I1 becomes smaller by the offset.
  • a third diode 19 having a cathode connected to the second switching element 16 and an anode connected to an end of the second winding 12C on the second switching element 16 side is provided. Thereby, it is possible to suppress a current from flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C, and it is possible to prevent a decrease in the voltage generated in the discharge start control.
  • discharge maintenance control is performed.
  • the first switching element 15 is always controlled to be in the open state.
  • the third switching element 14 and the second switching element 16 are closed, the primary current I1 flows from the power supply unit 17 to the second winding 12C as shown in FIG. Become.
  • the third switching element 14 to the open state the conduction of the primary current I1 flowing from the power supply unit 17 to the second winding 12C is interrupted.
  • the current return path L1 is provided in the ignition system 10, when the third switching element 14 is controlled to be in an open state, as shown in FIG.
  • the primary current I1 flows back to the second winding 12C via the current return path L1 due to the inductance of the second winding 12C.
  • the primary current I1 is gradually attenuated, and the absolute value of the secondary current I2 flowing through the spark plug 20 can be suppressed from decreasing stepwise and rapidly.
  • the primary current I1 flowing through the current return path L1 does not flow through the first winding 12B during the period when the discharge maintenance control is performed, It will flow directly to the winding 12C.
  • the influence of the first winding 12B is eliminated, and the primary current I1 can be controlled with high accuracy and responsiveness.
  • the primary current I1 repeatedly flows from the power supply unit 17 to the second winding 12C during the period in which the discharge maintenance control is performed.
  • the voltage that needs to be applied to the second winding 12C may be higher than a predetermined voltage that can be applied by the power supply unit 17. In this case, there is a concern that the primary current I1 cannot flow from the power supply unit 17 to the second winding 12C, and as a result, the spark discharge generated in the spark plug 20 cannot be maintained.
  • the ignition coil 11 is configured such that the turn ratio is larger than the voltage ratio obtained by dividing the discharge sustain voltage by a predetermined voltage applied by the power supply unit 17.
  • the discharge sustain voltage is a voltage when the spark discharge generated in the spark plug 20 by the discharge generation control is maintained.
  • the discharge sustaining voltage varies depending on the operating environment of the engine ECU, since the spark discharge generated in the spark plug 20 can be maintained within a range of 2 to 3 kV on average, the discharge maintaining voltage is within a range of 2 to 3 kV. Is set as a fixed value. That is, since the voltage ratio is a fixed value, the turn ratio increases as the number of turns of the second winding 12C decreases. As a result, the number of turns of the second winding 12C is reduced so that the turns ratio is larger than the voltage ratio, so that it is necessary to apply the second winding 12C to the second winding 12C during the period during which the discharge maintenance control is performed.
  • the voltage can be set to be lower than the voltage that can be applied by the power supply unit 17.
  • the primary current I1 can be repeatedly supplied from the power supply unit 17 to the second winding 12C, and the secondary current I2 flows through the spark plug 20 each time.
  • the spark discharge generated in the spark plug 20 can be maintained.
  • the ignition control circuit 30 sequentially detects the secondary current I2 flowing through the current detection path L2 during the period in which the discharge maintenance control is performed, and based on the detected secondary current I2.
  • the control shown in FIG. 6 is performed.
  • “secondary current I2” represents the value of the secondary current I2 flowing through the current detection path L2.
  • the “third control signal” indicates whether the third control signal is output to the third control terminal 14G of the third switching element 14 by high / low. Specifically, when the third control signal is output to the third control terminal 14G of the third switching element 14 (when the third control signal becomes high in FIG. 6), the third switching element 14 is controlled to be closed.
  • the third switching element 14 Controlled to open state.
  • the “second control signal” indicates whether the second control signal is output to the second control terminal 16G of the second switching element 16 by high / low.
  • the third switching element 14 and the second switching element 16 Is controlled to be closed.
  • the primary current I1 can flow from the power supply unit 17 to the second winding 12C, and the absolute value of the secondary current I2 flowing to the spark plug 20 increases accordingly.
  • the third switching element 14 is controlled to be in the open state. As a result, the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the absolute value of the secondary current I2 flowing through the spark plug 20 becomes small.
  • the secondary current I2 can be gradually changed, and can be easily within the range from the first threshold value to the second threshold value.
  • discharge control capable of preventing the discharge spark from being blown out can be performed.
  • Primary current I1 flowing through the first winding represents the primary current I1 flowing through the first winding 12B.
  • primary current I1 flowing through the second winding represents the primary current I1 flowing through the second winding 12C.
  • secondary voltage V2 represents the value of the secondary voltage V2 applied to the spark plug 20.
  • the “first control signal” indicates whether the first control signal is output to the first control terminal 15G of the first switching element 15 by high / low.
  • the discharge control is performed by the ignition control circuit 30 based on the ignition signal IGt output from the engine ECU.
  • the third control signal is transmitted to the third control terminal 14G of the third switching element 14, and the first control signal is transmitted to the first control terminal 15G of the first switching element 15 (time t1). reference).
  • the 3rd switching element 14 and the 1st switching element 15 are controlled to a closed state with the 2nd switching element 16 opened.
  • the primary current I1 flows from the power supply unit 17 to the first winding 12B, and the primary current I1 flowing through the first winding 12B increases.
  • the output of a 1st control signal is stopped in the state which has maintained the state with which the 3rd control signal was transmitted to the 3rd control terminal 14G of the 3rd switching element 14 ( Time t2).
  • the first switching element 15 is controlled to be in an open state, the primary current I1 flowing to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the spark plug 20 Spark discharge occurs.
  • discharge maintenance control is performed by the ignition control circuit 30.
  • the secondary current I2 flowing through the current detection path L2 is sequentially detected by the ignition control circuit 30.
  • the power source unit 17 supplies the second winding 12C so that the spark discharge generated in the spark plug 20 does not disappear.
  • Control in which the primary current I1 flows is performed.
  • the third switching element 14 is controlled to be in the closed state and the second switching element 16 is controlled to be in the open state. 16 to the second control terminal 16G.
  • the second switching element 16 is controlled to be closed, and the primary current I1 flows through the second winding 12C, and the secondary current I2 increases.
  • the output of the third control signal is stopped (see time t4).
  • the third switching element 14 is controlled to be in the open state, and the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the second winding is passed through the current return path L1.
  • the primary current I1 flows back to 12C.
  • the opening / closing operation of the third switching element 14 is controlled so that the absolute value of the secondary current I2 detected in the current detection path L2 is larger than the first threshold and smaller than the second threshold.
  • spark discharge continues to occur in the spark plug 20 until the discharge period ends (see time t3-5).
  • FIG. 7 assumes an operating condition in which the flow velocity in the combustion chamber changes every moment.
  • the secondary voltage V2 is not stable because the discharge spark length is extended or shortened by an air current or the like (see time t3-5).
  • the ignition system 10 can be operated even in an operation state where the secondary voltage V2 is not stable. Since the spark discharge generated in the spark plug 20 can be suppressed from being blown out, the spark discharge can be stably maintained.
  • FIG. 8 shows a structure around the case 50 in particular.
  • An ignition coil 11 is provided in the case 50, and a primary coil 12, a secondary coil 13, and an iron core 23 stacked vertically are mounted from the inside to the outside.
  • a predetermined space is formed between the iron core 23 and the case 50, and the third switching element 14, the first switching element 15, the second switching element 16, and the current are formed in the predetermined space.
  • a reflux path L1, a current detection path L2, and an ignition control circuit 30 are provided.
  • the prevention diode 21 is provided between the secondary coil 13 and the case 50, and the anode side of the prevention diode 21 is electrically connected to the first end of the secondary coil 13 by wiring.
  • the cathode side of the prevention diode 21 is connected to a current detection path L2 provided in the predetermined space.
  • the aspect of the discharge control according to the first embodiment has been described with reference to FIG.
  • FIG. 7 based on the ignition signal IGt output from the engine ECU, after the discharge control is performed by the ignition control circuit 30, spark discharge occurs in the spark plug 20, and the absolute value of the secondary current I2 is the first value.
  • the second switching element 16 is controlled to be in the open state
  • the third switching element 14 is controlled to be in the closed state.
  • the first switching element 15 is controlled to be in an open state, so that a high voltage is induced in the secondary coil 13, and thus the absolute value of the secondary current I ⁇ b> 2 is the first value.
  • a configuration may be adopted in which the output of the third control signal is stopped after the second control signal is output until it becomes smaller than one threshold (see time t8). Even with such a configuration, the operation and effect according to the above-described embodiment can be achieved.
  • the third switching element 14 is controlled to be closed when the absolute value of the detected secondary current I2 becomes smaller than the first threshold during the period in which the discharge maintenance control is performed.
  • the third switching element 14 is controlled to be in the open state.
  • the opening / closing control of the third switching element 14 may be controlled in a predetermined time regardless of the value of the secondary current I2.
  • the open / close state of the third switching element 14 may be switched each time the second predetermined time elapses during the period in which the discharge maintenance control is performed. In this case, since it is not necessary to detect the secondary current I2 during the period during which the discharge maintenance control is being performed, it is not necessary to form the current detection path L2, and the cost of the ignition system 10 can be reduced. Become.
  • the first switching element 15 is always controlled to be in the open state during the period when the discharge maintenance control is performed.
  • the third switching element 14 and the second switching element 16 are controlled to be closed, and the absolute value of the secondary current I2 is set to the second value.
  • the second switching element 16 is controlled to be in the closed state while the second switching element 16 is closed, so that the primary current I1 flowing from the power supply unit 17 to the second winding 12C is increased. Conduction and reflux were performed.
  • the first switching element 15 is always controlled to be in the open state during the period in which the discharge maintenance control is performed.
  • the third switching element 14 and the second switching element 16 are controlled to be closed, and the absolute value of the secondary current I2 is set to the second value.
  • the third switching element 14 is closed and the second switching element 16 is controlled to be opened, so that the primary current I1 flowing from the power supply unit 17 to the second winding 12C is increased. Conduction and interruption may be performed. This also has the same effect as the first embodiment.
  • the third diode 19 is provided in which the cathode side is connected to the second switching element 16 and the anode side is connected to the end of the second winding 12C on the second switching element 16 side. It was.
  • the third diode 19 is configured such that the cathode side is connected to the intermediate tap 12 ⁇ / b> A and the anode side is connected to the third ground side terminal 14 ⁇ / b> S of the third switching element 14. Also good.
  • the 3rd diode 19 can prevent the backflow of an electric current when the power supply part 17 is assembled
  • the cathode side of the first diode 18 provided in the current return path L1 is connected to the current path between the intermediate tap 12A and the third diode 19, and the anode side of the first diode 18 is grounded. It may be.
  • the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown).
  • the ignition signal IGt discharge start signal sets an energization period to the first winding 12B in the discharge start control (discharge generation control).
  • the energy input signal IGw current control signal sets the command value of the secondary current I2 and the end time of the discharge maintenance control in the discharge maintenance control.
  • the ignition control circuit 30 also controls the first control terminal 15G, the second control terminal 16G, and the third control terminal so as to control the opening / closing operations of the first switching element 15, the second switching element 16, and the third switching element 14. It is connected to the control terminal 14G. In addition, you may arrange
  • the energization period to the first winding 12B and the command value of the secondary current I2 in the discharge maintenance control are set by the ignition signal IGt and the energy input signal IGw. That is, the first winding 12B is energized while the ignition signal IGt is high. Further, a time difference is provided between the rising timing of the ignition signal IGt and the rising timing of the energy input signal IGw, and the command value of the secondary current I2 is set based on the length of this time difference.
  • the command value of the secondary current I2 is set to 100 ms
  • the command value of the secondary current I2 is set to 50 ms
  • the time difference is 2 ms
  • the secondary current I2 Is set to 20 ms.
  • the command value of the secondary current I2 may be set as the first threshold value
  • a value obtained by adding a predetermined value to the command value of the secondary current I2 may be set as the second threshold value.
  • the end timing of the discharge maintenance control is set according to the falling timing of the energy input signal IGw.
  • the setting of the energization period to the first winding 12B based on the ignition signal IGt, and the setting of the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw can also be applied to modified examples.
  • the second switching element 16 is controlled to be in an open state by the second control signal during the period when the discharge start control is performed. Then, when the ignition signal IGt rises, the first switching element 15 and the third switching element 14 are controlled to be closed by the first control signal and the third control signal, and the power supply unit 17 transfers to the first winding 12B. Primary current I1 flows. Then, when the ignition signal IGt falls, the first switching element 15 and the third switching element 14 are controlled to be opened by the first control signal and the third control signal. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
  • the discharge maintenance control is performed.
  • the first switching element 15 is controlled to be in an open state by the first control signal.
  • the second switching element 16 and the third switching element 14 are controlled to be closed by the second control signal and the third control signal, so that the primary current I1 is supplied from the power supply unit 17 to the second winding 12C. Will flow.
  • the third switching element 14 is controlled to be opened by the third control signal, so that the power supply unit 17 can supply the second winding 12C.
  • the conduction of the primary current I1 flowing through is interrupted.
  • the primary current I1 returns to the second winding 12C via the current return path L1, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases.
  • the third switching element 14 is again controlled to be closed by the third control signal.
  • a current return path L4 may be provided instead of the current return path L1.
  • the current return path L4 includes a second diode 41.
  • the cathode side of the second diode 41 is connected to the current path L5 between the second winding 12C and the second switching element 16, and the second diode 41
  • the anode side is connected to a current path L6 between the third diode 19 and the intermediate tap 12A.
  • the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown).
  • the ignition control circuit 30 sets the energization period for the first winding 12B based on the ignition signal IGt, and determines the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw. Set.
  • the mode of discharge start control is the same as in FIG. And discharge maintenance control is implemented after implementing discharge start control.
  • the first switching element 15 is controlled to be in an open state by the first control signal.
  • the second switching element 16 and the third switching element 14 are controlled to be closed by the second control signal and the third control signal, so that the primary current I1 is supplied from the power supply unit 17 to the second winding 12C. Will flow.
  • the second switching element 16 is controlled to be in an open state by the second control signal, so that the power supply unit 17 transfers to the second winding 12C.
  • the conduction of the primary current I1 flowing through is interrupted.
  • the primary current I1 returns to the second winding 12C via the current return path L4, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases.
  • the second switching element 16 is again controlled to be closed by the second control signal.
  • a current return path L4 including the second diode 41 is provided.
  • a fourth switching element 43 may be provided on the anode side of the second diode 41 in the current return path L4.
  • the fourth switching element 43 is a semiconductor switching element, and includes a fourth control terminal 43G, a fourth power supply side terminal 43D, and a fourth ground side terminal 43S.
  • the fourth switching element 43 controls on / off of energization between the fourth power supply side terminal 43D and the fourth ground side terminal 43S based on the fourth control signal input to the fourth control terminal 43G. It is configured.
  • the fourth power supply side terminal 43D is connected to the second diode 41
  • the fourth ground side terminal 43S is connected to the current path L5.
  • the second switching element 16 and the fourth switching element 43 are always controlled to be in the open state. Then, by controlling the third switching element 14 and the first switching element 15 to be closed, the primary current I1 flows from the power supply unit 17 to the first winding 12B. Then, the first switching element 15 is controlled to be in an open state after the first predetermined time has elapsed. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
  • discharge maintenance control is performed.
  • the first switching element 15 is always controlled to be in the open state.
  • the primary current I1 flows from the power supply unit 17 to the second winding 12C by controlling the third switching element 14, the second switching element 16, and the fourth switching element 43 to be closed. It will be.
  • the primary current I1 that flows from the power supply unit 17 to the second winding 12C is controlled by controlling the second switching element 16 to the open state. The continuity of is interrupted.
  • the primary current I1 returns to the second winding 12C via the current return path L4, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases.
  • the second switching element 16 is again controlled to be closed.
  • a return current flows with a voltage generated by a magnetic flux interlinked from the first winding 12B to the second winding 12C when a discharge occurs. It can suppress that secondary voltage V2 falls.
  • the intermediate tap 12A is connected to the power supply unit 17 via the third switching element 14.
  • the intermediate tap 12 ⁇ / b> A is directly connected to the power supply unit 17 by deleting the third switching element 14.
  • the ignition system 10 according to the second embodiment includes a current return path L4 instead of the current return path L1.
  • the current return path L4 includes a second diode 41.
  • the cathode side of the second diode 41 is connected to a current path L5 between the second winding 12C and the third diode 19, and the anode of the second diode 41 The side is connected to a current path L6 between the power supply unit 17 and the intermediate tap 12A.
  • the third diode 19 according to the second embodiment is connected to the second switching element 16 on the cathode side, and the anode side is the end of the second winding 12C on the second switching element 16 side. Connected to the department. As a result, it is possible to suppress a current from flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C during the discharge start control, and to prevent a decrease in the voltage generated during the discharge start control. it can.
  • discharge control can be simplified because the third switching element 14 need not be provided.
  • the cost of the ignition system 10 can be reduced.
  • FIG. 20 and FIG. 21 the aspect of the discharge control which concerns on 2nd embodiment is demonstrated.
  • the discharge control is performed by the ignition control circuit 30 based on the ignition signal IGt output from the engine ECU.
  • a first control signal is transmitted to the first control terminal 15G of the first switching element 15 (see time t11). Accordingly, the first switching element 15 is controlled to be closed while the second switching element 16 is kept open.
  • the primary current I1 flows from the power supply unit 17 to the first winding 12B, and the primary current I1 flowing through the first winding 12B increases.
  • the output of the first control signal is stopped (see time t12).
  • the first switching element 15 is controlled to be in an open state, the conduction of the primary current I1 flowing to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the spark plug 20 Spark discharge occurs.
  • discharge maintenance control is performed by the ignition control circuit 30.
  • the secondary current I2 flowing through the current detection path L2 is sequentially detected by the ignition control circuit 30.
  • the second control signal is transmitted to the second control terminal 16G of the second switching element 16 (see time t13).
  • the 2nd switching element 16 is controlled to a closed state, and the primary current I1 flows from the power supply part 17 to the 2nd coil
  • the output of the second control signal is stopped (see time t14).
  • the second switching element 16 is controlled to be in the open state, and the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the second winding is passed through the current return path L4.
  • the primary current I1 flows back to 12C, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases.
  • the second switching element 16 is again controlled to be closed.
  • the second switching is performed so that the absolute value of the secondary current I2 detected in the current detection path L2 is larger than the first threshold and smaller than the second threshold.
  • the conduction and interruption of the primary current I1 flowing through the first winding 12B can be performed by switching the first switching element 15 after controlling the second switching element 16 to the open state.
  • conduction and recirculation of the primary current I1 flowing through the second winding 12C can be performed by switching the second switching element 16 while controlling the first switching element 15 to be in an open state.
  • the primary current I1 flowing through the current return path L4 during the discharge sustaining control period does not flow to the first winding 12B but flows to the second winding 12C.
  • the primary current I1 can be accurately controlled without being affected by the winding 12B.
  • the controllability of the secondary current I2 can be improved, and as a result, an ignition device that is unlikely to misfire can be provided.
  • a predetermined space is formed between the iron core 23 and the case 50, and the first switching element 15, the second switching element 16, and the current return path are formed in the predetermined space.
  • L7, a current detection path L2, and an ignition control circuit 30 are provided.
  • the ignition system for the internal combustion engine can be accommodated in the space where the ignition coil 11 is accommodated in the ignition plug 20.
  • the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
  • the third diode 19 is configured such that the cathode side is connected to the intermediate tap 12 ⁇ / b> A and the anode side is connected to the power supply unit 17. Also good. Thereby, backflow when the power supply part 17 is assembled
  • the second switching element 16 is controlled to be closed when the absolute value of the detected secondary current I2 becomes smaller than the first threshold during the period when the discharge maintenance control is being performed.
  • the second switching element 16 is controlled to be in the open state.
  • the opening / closing control of the second switching element 16 may be controlled in a predetermined time regardless of the value of the secondary current I2.
  • the open / close state of the second switching element 16 may be switched every time the second predetermined time elapses during the period in which the discharge maintenance control is performed. In this case, since it is not necessary to detect the secondary current I2 during the period during which the discharge maintenance control is performed, it is not necessary to form the current detection path L2, and the ignition system 10 can be reduced in size and cost. Is possible.
  • the second diode 41 is provided in the current return path L4.
  • a fourth switching element 43 may be provided on the anode side of the second diode 41 in the current return path L4. In this case, operations and effects according to another example shown in FIG. 19 can be achieved.
  • the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown).
  • the ignition control circuit 30 sets the energization period for the first winding 12B based on the ignition signal IGt, and determines the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw. Set.
  • the ignition control circuit 30 controls the opening / closing operation of the first switching element 15, the second switching element 16, and the fourth switching element 43 so that the first control terminal 15G, the second control terminal 16G, and the fourth It is connected to the control terminal 43G.
  • the second diode 41 and the fourth switching element 43 may be arranged in reverse.
  • the second switching element 16 and the fourth switching element 43 are controlled to be in an open state by the second control signal and the fourth control signal during the period in which the discharge start control is performed.
  • the ignition signal IGt rises, whereby the first switching element 15 is controlled to be closed by the first control signal, and the primary current I1 flows from the power supply unit 17 to the first winding 12B.
  • the first switching element 15 is controlled to be in the open state by the first control signal.
  • the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
  • the discharge maintenance control is performed.
  • the first switching element 15 is controlled to be in the open state by the first control signal.
  • the second switching element 16 and the fourth switching element 43 in the closed state by the second control signal and the fourth control signal, the primary current I1 from the power supply unit 17 to the second winding 12C. Will flow.
  • the second switching element 16 is controlled to be in an open state by the second control signal, so that the power supply unit 17 transfers to the second winding 12C.
  • the conduction of the primary current I1 flowing through is interrupted.
  • the primary current I1 returns to the second winding 12C via the current return path L4, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases.
  • the second switching element 16 is again controlled to be closed by the second control signal.
  • the position of the third diode 19 can be changed from the position shown in FIG. 23 to the position shown in FIG. That is, as in the first embodiment, the third diode 19 has a cathode side connected to the second switching element 16 and an anode side connected to the end of the second winding 12C on the second switching element 16 side. In addition, you may arrange
  • the second power supply side terminal 16D of the second switching element 16 is connected to the second winding 12C via the third diode 19, and the second ground side terminal 16S is grounded.
  • the second switching element 16 is deleted and the third switching element 14 is added.
  • the third power supply side terminal 14D is connected to the intermediate tap 12A, and the third ground side terminal 14S of the third switching element 14 is connected to the second winding 12C.
  • the cathode side of the fourth diode 42 provided in the current return path L7 is connected to the current path L8 between the third switching element 14 and the second winding 12C, and the anode side of the fourth diode 42 is grounded. .
  • the primary current I1 flowing through the current return path L7 does not flow to the first winding 12B but directly flows to the second winding 12C, and thus is affected by the first winding 12B.
  • the primary current I1 can be controlled with high accuracy without any problem.
  • the third diode 19 has a cathode side connected to the ground side, and an anode side connected to the end of the second winding 12C opposite to the intermediate tap 12A side.
  • the discharge control is performed by the ignition control circuit 30 based on the ignition signal IGt output from the engine ECU.
  • a first control signal is transmitted to the first control terminal 15G of the first switching element 15 (see time t21).
  • the first switching element 15 is controlled to be closed while the third switching element 14 is kept open.
  • the primary current I1 flows from the power supply unit 17 to the first winding 12B, and the primary current I1 flowing through the first winding 12B increases.
  • the output of the first control signal is stopped (see time t22).
  • the first switching element 15 is controlled to be in an open state, the conduction of the primary current I1 flowing to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the spark plug 20 Spark discharge occurs.
  • discharge maintenance control is performed by the ignition control circuit 30.
  • the secondary current I2 flowing through the current detection path L2 is sequentially detected by the ignition control circuit 30.
  • the third control signal is transmitted to the third control terminal 14G of the third switching element 14 (see time t23).
  • the 3rd switching element 14 is controlled to a closed state, and the primary current I1 flows from the power supply part 17 to the 2nd coil
  • the output of the third control signal is stopped (see time t24).
  • the third switching element 14 is controlled to be in the open state, and the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the second winding is passed through the current return path L7.
  • the primary current I1 recirculates to 12C and attenuates.
  • the opening / closing operation of the third switching element 14 is controlled so that the absolute value of the secondary current I2 detected in the current detection path L2 is larger than the first threshold and smaller than the second threshold.
  • spark discharge continues to occur in the spark plug 20 until the discharge period ends (see time t23-25).
  • the conduction and interruption of the primary current I1 flowing through the first winding 12B can be performed by switching the first switching element 15 while controlling the third switching element 14 to be in an open state.
  • the conduction and recirculation of the primary current I1 flowing through the second winding 12C can be performed by switching the third switching element 14 after controlling the first switching element 15 to the open state.
  • the 3rd switching element 14 is remove
  • a predetermined space is formed between the iron core 23 and the case 50, and the first switching element 15, the third switching element 14, and the current return path are formed in the predetermined space.
  • L7, a current detection path L2, and an ignition control circuit 30 are provided.
  • the ignition system for the internal combustion engine can be accommodated in the space where the ignition coil 11 is accommodated in the ignition plug 20.
  • the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
  • the third embodiment can be implemented with the following modifications.
  • the third diode 19 has the cathode side connected to the ground side and the anode side connected to the end of the second winding 12C opposite to the intermediate tap 12A side.
  • the third diode 19 has the cathode side connected to the end of the second winding 12 ⁇ / b> C on the intermediate tap 12 ⁇ / b> A side and the anode side connected to the third switching element 14. It may be a configuration.
  • the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown).
  • the ignition control circuit 30 sets the energization period for the first winding 12B based on the ignition signal IGt, and determines the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw. Set.
  • the ignition control circuit 30 is connected to the third control terminal 14G so as to control the opening / closing operation of the third switching element 14. In addition, you may arrange
  • the third switching element 14 is controlled to be in an open state by the third control signal during the period when the discharge start control is being performed.
  • the ignition signal IGt rises, whereby the first switching element 15 is controlled to be closed by the first control signal, and the primary current I1 flows from the power supply unit 17 to the first winding 12B.
  • the first switching element 15 is controlled to be in the open state by the first control signal.
  • the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
  • the discharge maintenance control is performed.
  • the first switching element 15 is controlled to be in the open state by the first control signal.
  • the primary current I1 flows from the power supply unit 17 to the second winding 12C by controlling the third switching element 14 to be closed by the third control signal.
  • the third switching element 14 is controlled to be opened by the third control signal, so that the power supply unit 17 can supply the second winding 12C.
  • the conduction of the primary current I1 flowing through is interrupted.
  • the primary current I1 returns to the second winding 12C via the current return path L7, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases.
  • the third switching element 14 is again controlled to be closed by the third control signal.
  • the third switching element 14 is controlled to be closed when the absolute value of the detected secondary current I2 becomes smaller than the first threshold during the period when the discharge maintenance control is being performed.
  • the third switching element 14 is controlled to be in the open state.
  • the opening / closing control of the third switching element 14 may be controlled in a predetermined time regardless of the value of the secondary current I2.
  • the open / close state of the third switching element 14 may be switched each time the second predetermined time elapses during the period in which the discharge maintenance control is performed. In this case, since it is not necessary to detect the secondary current I2 during the period during which the discharge maintenance control is performed, it is not necessary to form the current detection path L2, and the ignition system 10 can be reduced in size and cost. Is possible.
  • the first switching element 15 is controlled to be closed while the third switching element 14 is open, and the first switching element 15 is opened after the first predetermined time has elapsed. Control to be controlled by the state was implemented.
  • the first switching element 15 is controlled to be closed, so that the primary current I1 flows from the power supply unit 17 to the first winding 12B while the third switching element 14 is closed. It is good also as a structure controlled to. As a result, the primary current I1 also flows through the second winding 12C, and as a result, the first winding 12B and the second winding 12C generate magnetic fluxes in directions that cancel each other's magnetic flux. become. As a result, as shown in FIG. 31, the secondary voltage V ⁇ b> 2 generated by performing the discharge generation control can also suppress the so-called on-voltage generated by performing the conventional discharge generation control. As a result, the voltage applied to the prevention diode 21 can be lowered, the prevention diode 21 can be reduced in voltage, or the prevention diode 21 can be omitted, and the cost of the ignition system 10 can be reduced. .
  • the signal line for transmitting the ignition signal IGt and the signal line for transmitting the energy input signal IGw to the ignition coil 11 are connected independently from an engine ECU (not shown).
  • a common signal line 51 for transmitting the energy input signal IGw may be connected to the engine ECU 61 (control device).
  • the signal lines 51a to 51d branched from the signal line 51 may be connected to the ignition control circuit 30 of each cylinder. That is, the energy input signal IGw may be common to all the cylinders # 1 to # 4.
  • the ignition signal IGt is an individual signal corresponding to each cylinder.
  • the high period of the energy input signal IGw continues from the period in which the ignition signal IGt is high to the time when the discharge maintenance control ends. For this reason, when the engine 60 is a multi-cylinder engine (for example, a V-type 6-cylinder engine), as shown in FIG. 33, if the energy input signal IGw is shared, the energy input signal IGw may always be high. That is, in the cylinder in which ignition by the spark plug 20 continues, the high periods of the energy input signal IGw may overlap.
  • a common signal line 52 for transmitting the energy input signal IGw1 and a common signal line 53 for transmitting the energy input signal IGw2 may be connected to the engine ECU 61. That is, the energy input signal IGw1 may be common to some cylinders # 1, # 3, and # 5 (one bank). The energy input signal IGw2 may be common to some cylinders # 2, # 4, and # 6 (the other bank).
  • the ignition signal IGt is an individual signal corresponding to each cylinder.
  • the signal lines 52a to 52c branched from the signal line 52 may be connected to the ignition control circuit 30 of the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5, respectively. Good.
  • the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5 are a group of cylinders in which ignition by the spark plug 20 does not continue.
  • the signal lines 53a to 53c branched from the signal line 53 may be connected to the ignition control circuit 30 of the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6, respectively. Good.
  • the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6 are a group of cylinders that are not continuously ignited by the spark plug 20, and are cylinders not included in the first cylinder group. It is a gathering. In other words, one cylinder (for example, the second cylinder group) (for example, one cylinder (for example, the first cylinder # 1, the third cylinder # 3)) is ignited in succession by the two cylinders (for example, the first cylinder # 1, the third cylinder # 3). Ignition is performed in the second cylinder # 2).
  • the ignition of the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5 in the first cylinder group is not continuous, and the first cylinder # 1, the third cylinder # 3 in the first cylinder group It can suppress that the high periods of energy input signal IGw1 transmitted to 5th cylinder # 5 overlap.
  • the ignition of the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6 in the second cylinder group is not continuous, and the second cylinder # 2, the fourth cylinder # 4, in the second cylinder group. It can suppress that the high periods of energy input signal IGw2 transmitted to 6th cylinder # 6 overlap. Therefore, even if the engine 60 is a multi-cylinder engine, the command value of the secondary current I2 and the end time of the discharge maintenance control can be set based on the energy input signals IGw1 and IGw2.
  • the engine 60 is not limited to a 6-cylinder engine, and may be an 8-cylinder engine, a 10-cylinder engine, or the like. Further, the cylinders of the engine 60 may be divided into three or more cylinder groups. And the cylinder of each cylinder group should just be a collection of the cylinders by which ignition by the spark plug 20 does not continue. Specifically, ignition is performed in cylinders included in another cylinder group (for example, the second cylinder group) while ignition is performed in succession on two cylinders included in each cylinder group (for example, the first cylinder group). Should just be done.
  • the ignition signal IGt and the energy input signal are supplied as shown in FIG.
  • Information included in IGw can be superimposed only on the ignition signal IGt. That is, after starting the discharge start control, energization to the first winding 12B is started by the first control signal at the first rise of the ignition signal IGt, and energization to the first winding 12B at the second rise. Exit. And discharge maintenance control is complete
  • the ignition control circuit 30 includes a signal information separation circuit 30a, a first control unit 30b, an energy superposition control unit 30c, a second control unit 30d, a fourth control unit 30e, and the like. ing.
  • the signal information dividing circuit 30a detects the rising timing and falling timing of the ignition signal IGt, and counts the number of rising times and the number of falling times.
  • the first control unit 30b and the fourth control unit 30e create a first control signal and a fourth control signal, respectively, based on information from the signal information separation circuit 30a.
  • the energy superposition control unit 30c and the second control unit 30d create a second control signal based on the information from the signal information separation circuit 30a and the detected secondary current I2.
  • the configuration described in Japanese Patent No. 4736942 can be employed.
  • the setting of the energization period to the first winding 12B based on the ignition signal IGt and the setting of the command value of the secondary current I2 and the end timing of the discharge maintenance control are also applied to other embodiments and their modifications. Can be applied.
  • the switching elements (third switching element 14 and second switching element 16) that are assumed to be MOSFETs may use IGBTs, power transistors, thyristors, triacs, or the like instead of MOSFETs.
  • a MOSFET, a power transistor, a thyristor, a triac, or the like may be used as the switching element (first switching element 15) that is assumed to be an IGBT.
  • the first switching element 15 may be connected to the fifth diode 15D (illustrated by a dotted line in FIG. 1) in antiparallel.
  • the fifth diode 15D in which the primary current I1 flowing to the second winding 12C is connected to the first switching element 15 in antiparallel. Then, the current flowing from the second winding 12C to the second switching element 16 through the first winding 12B is circulated. In this case, the current flowing back is affected by the first winding 12B, so that the magnitude of the current is reduced, and the secondary current I2 generated in the secondary coil 13 is accordingly reduced. There is a risk.
  • the present ignition system 10 has a configuration in which the fifth diode 15D is connected to the first switching element 15 in antiparallel. This can be said to be a suitable configuration.
  • the sustaining voltage is set within a range of 2 to 3 kV.
  • the discharge sustain voltage may be set to a value larger than 3 kV or a value smaller than 2 kV in accordance with the combustion state of the engine 60.
  • the third diode in which the cathode side is connected to the second switching element 16 and the anode side is connected to the end of the second winding 12C on the second switching element 16 side. 19 was provided.
  • a third diode 19 is provided in which the cathode side is connected to the ground side and the anode side is connected to the end of the second winding 12C opposite to the intermediate tap 12A side. It was.
  • the second switching element 16 or the third switching element 14 may be provided with an element (diode) having a backflow prevention function.
  • the ignition control circuit 30 generates and controls each control signal based on the ignition signal IGt received from the engine ECU, but the present invention is not limited to this. Any of these control signals may be individually received from the engine ECU and controlled.
  • the ignition system 10 excluding the power supply unit 17 and the spark plug 20 is housed in the case 50. About this, you may reduce the structure of the ignition system 10 accommodated in the case 50.
  • the ignition control circuit 30 may be deleted, and the control performed by the ignition control circuit 30 may be performed by an engine ECU that exists outside the case 50. In this case, the engine ECU corresponds to the ignition control circuit.
  • a switch element may be provided to perform opening / closing control such that it is closed during the reflux operation.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)

Abstract

An internal combustion engine ignition system provided with: a third switching element (14) which blocks or conducts a primary current that flows from a voltage application section (17) to a center tap (12A) of a primary coil (12); a first switching element (15) which is connected to one end side on a first winding (12B) side; a second switching element (16) which is connected to another end side on a second winding (12C) side; an ignition control circuit (30) which, by controlling the operation of each switching element, performs discharge generating control for causing an ignition plug to generate spark discharge, and discharge maintaining control for maintaining the spark discharge occurring at the ignition plug (20) by blocking or conducting the primary current flowing to the second winding; and a current backflow route (L1, L4, L7) for flowing back the current flowing from the second winding to the second switching element.

Description

内燃機関用点火システムIgnition system for internal combustion engines 関連出願の相互参照Cross-reference of related applications
　本出願は、２０１７年４月２０日に出願された日本出願番号２０１７－０８３８１６号と、２０１８年３月１９日に出願された日本出願番号２０１８－０５１０３１号に基づくもので、ここにその記載内容を援用する。 This application is based on Japanese Application No. 2017-083816 filed on April 20, 2017 and Japanese Application No. 2018-051031 filed on Mar. 19, 2018, and the contents thereof are described here. Is used.
　本開示は内燃機関に用いられる点火システムに関する。 The present disclosure relates to an ignition system used for an internal combustion engine.
　近年、自動車用内燃機関での燃費を改善させるため、希薄燃料の燃焼制御（リーンバーンエンジン）、又は、内燃機関のシリンダへ燃焼ガスを還流させるＥＧＲに関する技術の検討が進められている。これらの技術に対し、混合気に含まれる燃料を効果的に燃焼させる為、点火タイミング近傍の一定時間について点火プラグに持続的に火花放電を生じさせる継続放電方式が検討されている。 In recent years, in order to improve the fuel efficiency of an internal combustion engine for automobiles, studies are being made on technologies relating to combustion control of lean fuel (lean burn engine) or EGR for returning combustion gas to a cylinder of the internal combustion engine. For these techniques, in order to effectively burn the fuel contained in the air-fuel mixture, a continuous discharge method has been studied in which spark discharge is continuously generated in the spark plug for a certain time in the vicinity of the ignition timing.
　継続放電方式の点火システムとしては、例えば特許文献１に開示されるように、一次コイルの巻線の途中に中間タップが備わっており、点火プラグに主点火が開始された後、中間タップにエネルギ投入用の電源から電気エネルギが順次投入される。これにより、一次コイルの中間タップから一端までの巻線のみに電気エネルギの投入が行われ、それに伴って主点火による二次電流と同方向の二次電流が二次コイルに順次追加して流れることで、点火プラグに火花放電を継続して生じさせる。以降、一次コイルの中間タップから一端までの巻線を第二巻線と呼称し、中間タップから一次コイルの他端までの巻線を第一巻線と呼称する。このとき、第二巻線と二次コイルとの巻数比を大きく設けることで、昇圧回路を用いることなく、点火プラグに火花放電を継続して生じさせることが可能な大きさの二次電圧を二次コイルに発生させることが可能となるとしている。 As a continuous discharge type ignition system, as disclosed in Patent Document 1, for example, an intermediate tap is provided in the middle of the winding of the primary coil, and after the main ignition is started on the ignition plug, energy is supplied to the intermediate tap. Electrical energy is sequentially input from the input power source. As a result, electric energy is supplied only to the winding from the intermediate tap to one end of the primary coil, and accordingly, a secondary current in the same direction as the secondary current caused by the main ignition is sequentially added to the secondary coil and flows. Thus, spark discharge is continuously generated in the spark plug. Hereinafter, the winding from the intermediate tap to one end of the primary coil is referred to as a second winding, and the winding from the intermediate tap to the other end of the primary coil is referred to as a first winding. At this time, by providing a large turns ratio between the second winding and the secondary coil, a secondary voltage having a magnitude capable of continuously generating spark discharge in the spark plug without using a booster circuit is provided. It can be generated in the secondary coil.
特開２０１５－２００２８４号公報Japanese Patent Laid-Open No. 2015-200284
　ところで、特許文献１には、一次コイルの中間タップに電気エネルギを投入するエネルギ投入ラインをＯＮ－ＯＦＦするエネルギ投入用スイッチング素子が備わっている。このエネルギ投入用スイッチング素子がＯＮされる毎に、中間タップを介して第二巻線に一次電流が追加して流れることになる。一方で、エネルギ投入用スイッチング素子をオフすることでエネルギ投入を停止させる。この制御を繰り返しながら二次電流を所定の値に保持し着火性を高めている。しかし、開示者達はエネルギ投入用スイッチング素子をオフにしたときの一次電流の低下が比較的大きく、二次電流が急激に低下することで、二次電流を所定の値に保持させることが容易ではないことを見いだした。 Incidentally, Patent Document 1 is provided with an energy input switching element for turning on and off an energy input line for supplying electric energy to an intermediate tap of a primary coil. Each time the energy input switching element is turned ON, a primary current is additionally supplied to the second winding via the intermediate tap. On the other hand, the energy input is stopped by turning off the energy input switching element. While repeating this control, the secondary current is maintained at a predetermined value to improve the ignitability. However, the disclosing persons have a relatively large decrease in the primary current when the switching element for energy input is turned off, and the secondary current is rapidly decreased to easily maintain the secondary current at a predetermined value. I found something not.
　本開示は、上記課題を解決するためになされたものであり、その主たる目的は、放電維持制御期間中に二次電流が急激に小さくなることを抑制する事が可能な内燃機関用点火システムを提供することにある。 The present disclosure has been made to solve the above-described problems, and a main purpose thereof is to provide an internal combustion engine ignition system capable of suppressing a sudden decrease in secondary current during a discharge maintenance control period. It is to provide.
　第１の開示は、内燃機関用点火システムであって、内燃機関の燃焼室内の可燃混合気に点火するための火花放電を発生する点火プラグと、一次コイル及び二次コイルを具備し、前記二次コイルにより前記点火プラグに電圧を印加する点火コイルと、所定の電圧を前記一次コイルに印加する電圧印加部と、前記一次コイルを成す巻線の途中には中間タップが設けられており、前記電圧印加部から前記中間タップへと流れる一次電流の通電と遮断を行う第三スイッチング素子と、前記一次コイルを成す巻線のうち前記中間タップから一端までの巻線である第一巻線側の一端と接地側との間に接続される第一スイッチング素子と、前記一次コイルを成す巻線のうち前記中間タップから他端までの巻線である第二巻線側の一端と接地側との間に接続される第二スイッチング素子と、前記第一スイッチング素子の開閉状態と、前記第二スイッチング素子の開閉状態と、前記第三スイッチング素子の開閉状態と、をそれぞれ制御することで、前記第一巻線へ流れる前記一次電流の通電と遮断を行い前記点火プラグに前記火花放電を発生させる放電発生制御と、前記第二巻線へ流れる前記一次電流の通電と遮断を行い前記点火プラグに生じている前記火花放電を維持する放電維持制御と、を行なう点火制御回路と、前記第二巻線から前記第二スイッチング素子へと流れる電流を還流させる電流還流経路と、を備える。 A first disclosure is an ignition system for an internal combustion engine, and includes an ignition plug that generates a spark discharge for igniting a combustible air-fuel mixture in a combustion chamber of the internal combustion engine, a primary coil, and a secondary coil. An ignition tap that applies a voltage to the ignition plug by a secondary coil, a voltage application unit that applies a predetermined voltage to the primary coil, and an intermediate tap provided in the middle of the winding that forms the primary coil, A third switching element that performs energization and interruption of a primary current flowing from the voltage application unit to the intermediate tap, and a first winding side that is a winding from the intermediate tap to one end of the windings that form the primary coil. A first switching element connected between one end and the ground side, and one end on the second winding side, which is a winding from the intermediate tap to the other end of the windings forming the primary coil, and the ground side Connect between To the first winding by controlling the second switching element, the opening / closing state of the first switching element, the opening / closing state of the second switching element, and the opening / closing state of the third switching element, respectively. Discharge generation control for energizing and interrupting the primary current flowing to generate the spark discharge in the spark plug, and energizing and interrupting the primary current flowing to the second winding to cause the spark generated in the spark plug An ignition control circuit for performing discharge maintenance control for maintaining discharge, and a current return path for returning current flowing from the second winding to the second switching element.
　放電発生制御では、第一スイッチング素子の開閉状態と、第二スイッチング素子の開閉状態と、第三スイッチング素子の開閉状態と、がそれぞれ制御され、第一巻線へ流れる一次電流の導通と遮断が行われることで、点火プラグに火花放電を発生させる。また、放電維持制御では、第一スイッチング素子の開閉状態と、第二スイッチング素子の開閉状態と、第三スイッチング素子の開閉状態と、がそれぞれ制御され、第二巻線へ流れる一次電流の導通と遮断が行われることで、点火プラグに生じている火花放電が維持される。このとき、仮に電流還流経路がなければ、放電維持制御中に第一スイッチング素子と第三スイッチング素子とが開状態となると、第二巻線に流れる一次電流が流れず遮断され、その期間、点火プラグに流れる二次電流がステップ的に大きく低下する懸念がある。この点、本内燃機関用点火システムは、電流還流経路が設けられているため、放電維持制御中に第一スイッチング素子と第三スイッチング素子とが開状態となっても、電流還流経路から第二巻線に一次電流が流れながら緩やかに減衰することになる。これにより、点火プラグに流れる二次電流がステップ的に急激に小さくなることを抑制することができる。また、第一スイッチング素子に逆方向ダイオードが備えられている場合には、逆方向ダイオード、第一巻線１２Ｂを経由して第二巻線１２Ｃの電流還流経路が存在するが、第一巻線１２Ｂに発生する電圧の影響を受け、第二巻線１２Ｃの還流電流は少なくなり、やはり二次電流が急激に小さくなる。 In the discharge generation control, the open / close state of the first switching element, the open / close state of the second switching element, and the open / close state of the third switching element are respectively controlled, and conduction and interruption of the primary current flowing to the first winding are controlled. As a result, spark discharge is generated in the spark plug. In the discharge maintenance control, the open / close state of the first switching element, the open / close state of the second switching element, and the open / close state of the third switching element are controlled, respectively, and the conduction of the primary current flowing to the second winding is controlled. By performing the interruption, the spark discharge generated in the spark plug is maintained. At this time, if there is no current return path, when the first switching element and the third switching element are opened during the discharge maintenance control, the primary current flowing through the second winding is interrupted without being interrupted. There is a concern that the secondary current flowing through the plug may be greatly reduced stepwise. In this regard, since the internal combustion engine ignition system is provided with a current return path, even if the first switching element and the third switching element are opened during the discharge maintenance control, As the primary current flows through the winding, it gradually attenuates. Thereby, it can suppress that the secondary current which flows into a spark plug becomes small in steps. When the first switching element is provided with a reverse diode, there is a current return path for the second winding 12C via the reverse diode and the first winding 12B. Under the influence of the voltage generated at 12B, the return current of the second winding 12C decreases, and the secondary current also decreases rapidly.
　第２の開示は、第１の開示において、前記電流還流経路は第一ダイオードを備え、前記第一ダイオードのカソード側は前記中間タップに接続されており、前記第一ダイオードのアノード側は接地側に接続されている。 According to a second disclosure, in the first disclosure, the current return path includes a first diode, a cathode side of the first diode is connected to the intermediate tap, and an anode side of the first diode is a ground side. It is connected to the.
　これにより、放電維持制御期間中、電流還流部を流れる一次電流は第一巻線に流れず、直接第二巻線に流れることとなるため、第一巻線の影響を受けることなく一次電流を精度高く制御することが可能となる。 Thereby, during the discharge maintenance control period, the primary current flowing through the current return portion does not flow to the first winding, but flows directly to the second winding. Therefore, the primary current is not affected by the first winding. It becomes possible to control with high accuracy.
　第３の開示は、第１又は第２の開示において、前記点火制御回路は、前記第二スイッチング素子を開状態に制御した上で、前記第一スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる前記一次電流の導通と遮断を行い、前記第一スイッチング素子を開状態に制御した上で、前記第二スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第三スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う。 According to a third disclosure, in the first or second disclosure, the ignition control circuit controls the second switching element to an open state, and then closes the first switching element and the third switching element. Controlling, and then controlling the first switching element to an open state, conducting and blocking the primary current flowing to the first winding, and controlling the first switching element to an open state, The second switching element and the third switching element are controlled to be closed, and then the third switching element is controlled to be opened, thereby conducting and circulating the primary current flowing to the second winding. .
　上記構成とすることで、第一巻線に流れる一次電流の導通と遮断は、第二スイッチング素子を開状態に制御し、第三スイッチング素子を閉状態に制御した上で、第一スイッチング素子を切替ることにより実施することができる。また、第二巻線に流れる一次電流の導通と還流は、第一スイッチング素子を開状態に制御し、第二スイッチング素子を閉状態に制御した上で、第三スイッチング素子を切替ることにより実施することができる。 With the above configuration, the conduction and interruption of the primary current flowing through the first winding is controlled by opening the second switching element and controlling the third switching element to the closed state. It can be implemented by switching. Also, the conduction and recirculation of the primary current flowing through the second winding is performed by controlling the first switching element to the open state and controlling the second switching element to the closed state, and then switching the third switching element. can do.
　第４の開示は、第１又は第２の開示において、前記点火制御回路は、前記第二スイッチング素子を開状態に制御した上で、前記第一スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる前記一次電流の導通と遮断を行い、前記第一スイッチング素子を開状態に制御した上で、前記第二スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第二スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と遮断を行う。 According to a fourth disclosure, in the first or second disclosure, the ignition control circuit controls the second switching element to an open state, and then closes the first switching element and the third switching element. Controlling, and then controlling the first switching element to an open state, conducting and blocking the primary current flowing to the first winding, and controlling the first switching element to an open state, Controlling the second switching element and the third switching element to a closed state, and then controlling the second switching element to an open state allows conduction and interruption of the primary current flowing to the second winding. .
　第５の開示は、内燃機関用点火システムであって、内燃機関の燃焼室内の可燃混合気に点火するための火花放電を発生する点火プラグと、一次コイル及び二次コイルを具備し、前記二次コイルにより前記点火プラグに電圧を印加する点火コイルと、前記一次コイルを成す巻線の途中には中間タップが設けられており、所定の電圧を前記中間タップに印加する電圧印加部と、前記一次コイルを成す巻線のうち前記中間タップから一端までの巻線である第一巻線側の一端と接地側との間に接続される第一スイッチング素子と、前記一次コイルを成す巻線のうち前記中間タップから他端までの巻線である第二巻線側の一端と接地側との間に接続される第二スイッチング素子と、前記第一スイッチング素子の開閉状態と、前記第二スイッチング素子の開閉状態と、をそれぞれ制御することで、前記第一巻線へ流れる前記一次電流の導通と遮断を行い前記点火プラグに前記火花放電を発生させる放電発生制御と、前記第二巻線へ流れる前記一次電流の導通と遮断を行い前記点火プラグに生じている前記火花放電を維持する放電維持制御と、を行なう点火制御回路と、前記第二スイッチング素子で第二巻線の電流を遮断したときに第二巻線の流れる電流を還流させる電流還流経路と、を備える。 A fifth disclosure is an ignition system for an internal combustion engine, and includes an ignition plug that generates a spark discharge for igniting a combustible mixture in a combustion chamber of the internal combustion engine, a primary coil, and a secondary coil. An ignition coil that applies a voltage to the ignition plug by a secondary coil, an intermediate tap provided in the middle of the winding that forms the primary coil, a voltage application unit that applies a predetermined voltage to the intermediate tap, and Of the windings forming the primary coil, the first switching element connected between one end on the first winding side that is the winding from the intermediate tap to one end and the ground side, and the winding of the winding forming the primary coil A second switching element connected between one end on the second winding side which is a winding from the intermediate tap to the other end and the ground side, an open / close state of the first switching element, and the second switching element By controlling each of the open and closed states, discharge generation control for conducting and blocking the primary current flowing to the first winding and generating the spark discharge in the spark plug, and the flow flowing to the second winding An ignition control circuit that conducts and cuts off the primary current and maintains the spark discharge generated in the spark plug; and an ignition control circuit that cuts off the current of the second winding by the second switching element. A current return path for returning the current flowing through the second winding.
　放電発生制御では、第一スイッチング素子の開閉状態と、第二スイッチング素子の開閉状態と、がそれぞれ制御され、第一巻線へ流れる一次電流の導通と遮断が行われることで、点火プラグに火花放電を発生させる。また、放電維持制御では、第一スイッチング素子の開閉状態と、第二スイッチング素子の開閉状態と、がそれぞれ制御され、第二巻線へ流れる一次電流の導通と遮断が行われることで、点火プラグに生じている火花放電が維持される。このとき、仮に電流還流経路がなければ、放電維持制御中に第一スイッチング素子と第二スイッチング素子とが開状態となると、第二巻線に流れる一次電流が流れず遮断され、その期間、点火プラグに流れる二次電流がステップ的に大きく低下する懸念がある。この点、本内燃機関用点火システムは、電流還流経路が設けられているため、放電維持制御中に第一スイッチング素子と第二スイッチング素子とが開状態となっても、電流還流経路から第二巻線に一次電流が減衰しながら流れることになる。これにより、点火プラグに流れる二次電流がステップ的に急激に小さくなることを抑制することができる。 In the discharge generation control, the open / close state of the first switching element and the open / close state of the second switching element are controlled, and the primary current flowing through the first winding is turned on and off, thereby sparking the spark plug. Generate a discharge. Further, in the discharge maintenance control, the open / close state of the first switching element and the open / close state of the second switching element are respectively controlled, and conduction and interruption of the primary current flowing to the second winding is performed, so that the spark plug The spark discharge that occurs is maintained. At this time, if there is no current return path, when the first switching element and the second switching element are opened during the discharge maintenance control, the primary current flowing through the second winding is interrupted without being interrupted. There is a concern that the secondary current flowing through the plug may be greatly reduced stepwise. In this regard, since the internal combustion engine ignition system is provided with a current return path, even if the first switching element and the second switching element are opened during the discharge maintenance control, The primary current flows through the winding while being attenuated. Thereby, it can suppress that the secondary current which flows into a spark plug becomes small in steps.
　第６の開示は、第５の開示において、前記電流還流経路は第二ダイオードを備え、前記第二ダイオードのカソード側は前記電圧印加部と前記中間タップとの間の電流経路に接続されており、前記第二ダイオードのアノード側は前記第二巻線と前記第二スイッチング素子との間の電流経路に接続されている。 According to a sixth disclosure, in the fifth disclosure, the current return path includes a second diode, and a cathode side of the second diode is connected to a current path between the voltage application unit and the intermediate tap. The anode side of the second diode is connected to the current path between the second winding and the second switching element.
　これにより、放電維持制御期間中、電流還流部を流れる一次電流は第一巻線に流れず、第二巻線に減衰しながら流れることとなるため、第一巻線の影響を受けることなく一次電流を精度高く制御することが可能となる。 As a result, during the discharge maintenance control period, the primary current flowing through the current return portion does not flow to the first winding, but flows while being attenuated to the second winding. Therefore, the primary current is not affected by the first winding. It becomes possible to control the current with high accuracy.
　第７の開示は、第５又は６の開示において、前記点火制御回路は、前記放電発生制御として、前記第二スイッチング素子を開状態に制御した上で、前記第一スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる一次電流の導通と遮断を行い、前記放電維持制御として、前記第一スイッチング素子を開状態に制御した上で、前記第二スイッチング素子を閉状態に制御し、そのあと前記第二スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う。 According to a seventh disclosure, in the fifth or sixth disclosure, the ignition control circuit controls the second switching element to an open state and controls the first switching element to a closed state as the discharge generation control. Then, by controlling the first switching element to the open state, the primary current flowing to the first winding is turned on and off, and the first switching element is controlled to the open state as the discharge maintenance control. Then, the second switching element is controlled to be closed, and then the second switching element is controlled to be opened, thereby conducting and refluxing the primary current flowing to the second winding.
　上記構成とすることで、第一巻線に流れる一次電流の導通と遮断は、第二スイッチング素子を開状態に制御した上で、第一スイッチング素子を切替ることにより実施することができる。また、第二巻線に流れる一次電流の導通と還流は、第一スイッチング素子を開状態に制御した上で、第二スイッチング素子を切替ることにより実施することができる。 With the above configuration, the conduction and interruption of the primary current flowing through the first winding can be performed by switching the first switching element while controlling the second switching element to the open state. Further, conduction and recirculation of the primary current flowing through the second winding can be performed by switching the second switching element after controlling the first switching element to be in an open state.
　第８の開示は、第１乃至７のいずれか１つの開示において、カソード側は前記第二スイッチング素子に接続されており、アノード側は前記中間タップ側とは反対側の端部に接続されている第三ダイオードを備える。 According to an eighth disclosure, in any one of the first to seventh disclosures, the cathode side is connected to the second switching element, and the anode side is connected to an end opposite to the intermediate tap side. A third diode.
　仮に第三ダイオードが設けられていない場合、放電開始制御を実施することで、第二スイッチング素子から第二巻線を介して電圧印加部へと流れる電流が発生する可能性がある。つまり、第一巻線の遮断電流によって発生する磁束が第二巻線に鎖交することで、第二巻線の端部に電圧が発生し前記電流が発生する可能性がある。この場合、第ニスイッチング素子から電圧印加部へと流れる電流により相殺され、一次電流は相殺された分だけ小さくなることになる。この対策として、カソード側が第二スイッチング素子に接続されており、アノード側が第二巻線における第二スイッチング素子側の端部に接続されている第三ダイオードを設けることで、前記電流が生じるような電圧が発生しても第二スイッチング素子から電圧印加部へと流れることを抑制する事が可能となる。 If the third diode is not provided, a current that flows from the second switching element to the voltage application unit through the second winding may be generated by performing the discharge start control. That is, when the magnetic flux generated by the cut-off current of the first winding is linked to the second winding, a voltage is generated at the end of the second winding and the current may be generated. In this case, the current flowing from the second switching element to the voltage application unit is canceled out, and the primary current is reduced by the amount canceled. As a countermeasure, the current is generated by providing a third diode whose cathode side is connected to the second switching element and whose anode side is connected to the end of the second winding on the second switching element side. Even if the voltage is generated, it is possible to suppress the flow from the second switching element to the voltage application unit.
　第９の開示は、第１乃至７のいずれか１つの開示において、カソード側は前記中間タップに接続されており、アノード側は前記電圧印加部に接続されている第三ダイオードを備える。 In a ninth disclosure, in any one of the first to seventh disclosures, a cathode side is connected to the intermediate tap, and an anode side includes a third diode connected to the voltage application unit.
　このことから、放電開始制御によって第二スイッチング素子から第二巻線を介して電圧印加部へと電流が流れようとする電圧が発生しても、第二スイッチング素子から電圧印加部へと電流が流れることを抑制する事が可能となる。 Therefore, even if a voltage is generated from the second switching element to the voltage application unit through the second winding by the discharge start control, the current is supplied from the second switching element to the voltage application unit. It is possible to suppress the flow.
　第１０の開示は、内燃機関用点火システムであって、内燃機関の燃焼室内の可燃混合気に点火するための火花放電を発生する点火プラグと、一次コイル及び二次コイルを具備し、前記二次コイルにより前記点火プラグに電圧を印加する点火コイルと、前記一次コイルを成す巻線の途中には中間タップが設けられており、所定の電圧を前記中間タップに印加する電圧印加部と、前記一次コイルを成す巻線のうち前記中間タップから一端までの巻線である第一巻線側の一端と接地側との間に接続される第一スイッチング素子と、前記中間タップと、前記中間タップから他端までの巻線である第二巻線と、の間に接続される第三スイッチング素子と、前記第一スイッチング素子の開閉状態と、前記第三スイッチング素子の開閉状態と、をそれぞれ制御することで、前記点火プラグに前記火花放電を発生させる放電発生制御と、前記点火プラグに生じている前記火花放電を維持する放電維持制御と、を行なう点火制御回路と、前記第二巻線から接地側へと流れる電流を還流させる電流還流経路と、を備える。 A tenth disclosure is an ignition system for an internal combustion engine, and includes an ignition plug that generates a spark discharge for igniting a combustible air-fuel mixture in a combustion chamber of the internal combustion engine, a primary coil, and a secondary coil. An ignition coil that applies a voltage to the ignition plug by a secondary coil, an intermediate tap provided in the middle of the winding that forms the primary coil, a voltage application unit that applies a predetermined voltage to the intermediate tap, and A first switching element connected between one end on the first winding side that is a winding from the intermediate tap to one end of the winding forming the primary coil and the ground side, the intermediate tap, and the intermediate tap A third switching element connected between the second winding that is a winding from the other end to the other end, an open / close state of the first switching element, and an open / close state of the third switching element, respectively An ignition control circuit for performing a discharge generation control for generating the spark discharge in the spark plug and a discharge maintaining control for maintaining the spark discharge generated in the spark plug; and the second winding And a current return path for returning the current flowing from the ground to the ground side.
　放電発生制御では、第一スイッチング素子の開閉状態と、第三スイッチング素子の開閉状態と、がそれぞれ制御され、第一巻線へ流れる一次電流の導通と遮断が行われることで、点火プラグに火花放電を発生させる。また、放電維持制御では、第一スイッチング素子の開閉状態と、第三スイッチング素子の開閉状態と、がそれぞれ制御され、第二巻線へ流れる一次電流の導通と遮断が行われることで、点火プラグに生じている火花放電が維持される。このとき、仮に電流還流経路がなければ、放電維持制御中に第一スイッチング素子と第三スイッチング素子とが開状態となると、第二巻線に流れる一次電流が流れず遮断され、その期間、点火プラグに流れる二次電流がステップ的に大きく低下する懸念がある。この点、本内燃機関用点火システムは、電流還流経路が設けられているため、放電維持制御中に第一スイッチング素子と第三スイッチング素子とが開状態となっても、第二巻線のインダクタンス成分により電流還流経路から第二巻線に一次電流が緩やかに減衰しながら流れることになる。これにより、点火プラグに流れる二次電流がステップ的かつ、急激に小さくなることを抑制することができる。 In the discharge generation control, the open / close state of the first switching element and the open / close state of the third switching element are controlled, and the primary current flowing through the first winding is turned on and off to spark the spark plug. Generate a discharge. In the discharge maintenance control, the open / close state of the first switching element and the open / close state of the third switching element are controlled, and the conduction and blocking of the primary current flowing to the second winding are performed, so that the spark plug The spark discharge that occurs is maintained. At this time, if there is no current return path, when the first switching element and the third switching element are opened during the discharge maintenance control, the primary current flowing through the second winding is interrupted without being interrupted. There is a concern that the secondary current flowing through the plug may be greatly reduced stepwise. In this regard, since the internal combustion engine ignition system is provided with a current return path, even if the first switching element and the third switching element are opened during the discharge maintenance control, the inductance of the second winding Due to the component, the primary current flows from the current return path to the second winding while being gradually attenuated. Thereby, it can suppress that the secondary current which flows into a spark plug becomes small stepwise and rapidly.
　第１１の開示は、第１０の開示において、前記電流還流経路は第四ダイオードを備え、前記第四ダイオードのカソード側は前記第三スイッチング素子と前記第二巻線との間の電流経路に接続されており、前記第四ダイオードのアノード側は接地側に接続されている。 An eleventh disclosure is the tenth disclosure, wherein the current return path includes a fourth diode, and a cathode side of the fourth diode is connected to a current path between the third switching element and the second winding. The anode side of the fourth diode is connected to the ground side.
　これにより、放電維持制御期間中、電流還流部を流れる一次電流は第一巻線に流れず、直接第二巻線に流れることとなるため、第一巻線の影響を受けることなく一次電流は、ステップ的に小さくならず、緩やかに減衰していく。一次電流が所定の値に達したら、再度第三スイッチング素子から電流を投入する。再度所定の値に達したら第三スイッチング素子をオフさせる制御を繰り返すので一次電流を精度良く所定の値に制御することが可能となる。 Thereby, during the discharge maintenance control period, the primary current flowing through the current return portion does not flow to the first winding, but flows directly to the second winding, so that the primary current is not affected by the first winding. It does not decrease step by step, but gradually attenuates. When the primary current reaches a predetermined value, the current is supplied again from the third switching element. When the predetermined value is reached again, the control to turn off the third switching element is repeated, so that the primary current can be accurately controlled to the predetermined value.
　第１２の開示は、第１０又は１１の開示において、カソード側は接地側に接続されており、アノード側は前記第二巻線における前記中間タップ側とは反対側の端部に接続されている第三ダイオードを備える。 In a twelfth disclosure, in the tenth or eleventh disclosure, the cathode side is connected to the ground side, and the anode side is connected to an end of the second winding opposite to the intermediate tap side. A third diode is provided.
　仮に第三ダイオードが設けられていない場合、放電開始制御を実施することで、第二巻線から第三スイッチング素子を介して電圧印加部へと流れる電流が発生する可能性がある。この場合、第一巻線の遮断電流によって発生する磁束が第二スイッチング素子から電圧印加部へと流れる電流により相殺され、一次電流は相殺された分だけ小さくなることになる。この対策として、カソード側が第二スイッチング素子に接続されており、アノード側が第二巻線における第二スイッチング素子側の端部に接続されている第三ダイオードを設けることで、前記電流が生じるような電圧が放電開始制御で発生しても第三スイッチング素子から電圧印加部へと流れることを抑制する事が可能となる。 If a third diode is not provided, a current that flows from the second winding to the voltage application unit via the third switching element may be generated by performing the discharge start control. In this case, the magnetic flux generated by the breaking current of the first winding is canceled by the current flowing from the second switching element to the voltage application unit, and the primary current is reduced by the amount canceled. As a countermeasure, the current is generated by providing a third diode whose cathode side is connected to the second switching element and whose anode side is connected to the end of the second winding on the second switching element side. Even if the voltage is generated by the discharge start control, it is possible to suppress the flow from the third switching element to the voltage application unit.
　第１３の開示は、第１０又は１１の開示において、カソード側は前記第二巻線における前記中間タップ側の端部に接続されており、アノード側は前記第三スイッチング素子に接続されている第三ダイオードを備える。 In a thirteenth disclosure according to the tenth or eleventh disclosure, a cathode side is connected to an end portion of the intermediate tap side in the second winding, and an anode side is connected to the third switching element. Equipped with three diodes.
　この構成によっても、放電開始制御時に第二巻線から第三スイッチング素子を介して電圧印加部へと流れる電流が生じるような電圧が発生しても、第三ダイオードにより第二巻線から第三スイッチング素子へと流れることを抑制する事が可能となる。 Even with this configuration, even when a voltage is generated that causes a current to flow from the second winding to the voltage applying unit via the third switching element during the discharge start control, the third diode causes the third winding to It is possible to suppress the flow to the switching element.
　第１４の開示は、第１０乃至１３のいずれか１つの開示において、前記点火制御回路は、前記放電発生制御として、前記第三スイッチング素子を開状態に制御した上で、前記第一スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる一次電流の導通と遮断を行い放電を開始させ、前記放電維持制御として、前記第一スイッチング素子を開状態に制御した上で、前記第三スイッチング素子を状態に制御し、そのあと前記第三スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う。 In a fourteenth disclosure according to any one of the tenth to thirteenth disclosures, the ignition control circuit controls the third switching element to an open state as the discharge generation control, and then switches the first switching element. By controlling to the closed state and then controlling the first switching element to the open state, the primary current flowing to the first winding is turned on and off to start discharging, and as the discharge maintenance control, After controlling one switching element to an open state, controlling the third switching element to a state, and then controlling the third switching element to an open state, the primary current flowing to the second winding Conduct conduction and reflux.
　上記構成とすることで、第一巻線に流れる一次電流の導通と遮断は、第三スイッチング素子を開状態に制御した上で、第一スイッチング素子を切替ることにより実施することができる。また、第二巻線に流れる一次電流の導通と還流を、第一スイッチング素子を開状態に制御した上で、第三スイッチング素子を切替ることにより実施することができる。 With the above configuration, the conduction and interruption of the primary current flowing through the first winding can be performed by switching the first switching element after controlling the third switching element to the open state. Further, conduction and recirculation of the primary current flowing through the second winding can be performed by switching the third switching element while controlling the first switching element to the open state.
　第１５の開示は、第１０乃至１３のいずれか１つの開示において、前記点火制御回路は、前記放電発生制御として、前記第一スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子及び前記第三スイッチング素子を開状態に制御することで、前記第一巻線及び前記第二巻線へと流れる一次電流の導通と遮断を行い放電を開始させ、前記放電維持制御として、前記第一スイッチング素子を開状態に制御した上で、前記第三スイッチング素子を閉状態に制御し、そのあと前記第三スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う。 According to a fifteenth disclosure, in any one of the tenth to thirteenth disclosures, the ignition control circuit controls the first switching element and the third switching element to be closed as the discharge generation control, and then By controlling the first switching element and the third switching element to an open state, the primary current flowing to the first winding and the second winding is turned on and off to start discharging, and the discharge is maintained. As the control, the first switching element is controlled to be in an open state, the third switching element is controlled to be in a closed state, and then the third switching element is controlled to be in an open state. Conduction and recirculation of the primary current flowing to
　放電発生制御時に、第一スイッチング素子及び第三スイッチング素子を閉状態に制御することで、第二巻線にも一次電流が流れることになり、その結果、第一巻線と第二巻線とにそれぞれ、互いの磁束を打ち消し合う方向の磁束が発生することになる。これにより、放電発生制御の通電で二次側に発生する所謂オン電圧を抑えることができ、オン電圧飛び火防止ダイオードを削除したり、低電圧化して安価なダイオードを採用したりすることができる。 By controlling the first switching element and the third switching element in the closed state during the discharge generation control, a primary current flows through the second winding. As a result, the first winding and the second winding In this case, magnetic fluxes are generated in directions that cancel each other's magnetic fluxes. As a result, the so-called on-voltage generated on the secondary side due to the energization of the discharge generation control can be suppressed, and the on-voltage spark prevention diode can be eliminated, or a low-voltage and inexpensive diode can be employed.
　第１６の開示は、第１乃至１５のいずれか１つの開示において、前記第一巻線の巻数は、前記第二巻線の巻数よりも多い。 According to a sixteenth disclosure, in any one of the first to fifteenth disclosures, the number of turns of the first winding is larger than the number of turns of the second winding.
　放電維持制御時において、点火プラグに生じている放電を維持するための電圧は、放電発生制御時において、点火プラグに放電を発生させるために必要な電圧よりも低い。これを考慮し、第一巻線の巻数を、第二巻線の巻数よりも多くすることで、第二巻線に一次電圧を印加した場合に二次コイルに発生する二次電圧を、第一巻線に一次電圧を印加した場合に二次コイルに発生する二次電圧よりも低くすることができる。 During discharge maintenance control, the voltage for maintaining the discharge generated in the spark plug is lower than the voltage required for causing the spark plug to generate discharge during the discharge generation control. Considering this, by making the number of turns of the first winding larger than the number of turns of the second winding, the secondary voltage generated in the secondary coil when the primary voltage is applied to the second winding, When a primary voltage is applied to one winding, it can be made lower than the secondary voltage generated in the secondary coil.
　第１７の開示は、第１乃至１６のいずれか１つの開示において、前記二次コイルの巻数を前記第二巻線の巻数で割った値である巻数比が、前記放電発生制御により前記点火プラグに発生させた前記火花放電を維持するために必要な電圧としての放電維持電圧を、前記電圧印加部が印加する前記電圧で割った値である電圧比よりも大きくなるように構成される。 A seventeenth disclosure is the spark plug according to any one of the first to sixteenth disclosures, wherein a turn ratio, which is a value obtained by dividing the number of turns of the secondary coil by the number of turns of the second winding, is determined by the discharge generation control. The discharge sustaining voltage, which is a voltage necessary for maintaining the spark discharge generated in step 1, is configured to be larger than a voltage ratio that is a value obtained by dividing the discharge sustaining voltage by the voltage applied by the voltage applying unit.
　巻数比は、二次コイルの巻数を第二巻線の巻数で割ることで算出される。つまり、二次巻線の巻数が少なくなるほど、巻数比は大きくなる。このとき、電源電圧と放電維持電圧との比よりも巻数比が大きくなるように二次巻線の巻数を少なくすると、放電維持制御期間中に第二巻線に印加される電圧は電圧印加部が印加する電圧よりも低くなるように設定できる。これにより、放電維持制御の実施期間中、二次巻線に電圧印加部から一次電流を繰り返し流すことができ、そのたび点火プラグに二次電流が流れ、その結果として点火プラグに発生している火花放電を維持することができる。 The turn ratio is calculated by dividing the number of turns of the secondary coil by the number of turns of the second winding. That is, the smaller the number of turns of the secondary winding, the larger the turns ratio. At this time, if the number of turns of the secondary winding is reduced so that the turn ratio is larger than the ratio of the power supply voltage and the discharge sustain voltage, the voltage applied to the second winding during the discharge sustain control period is Can be set to be lower than the applied voltage. As a result, the primary current can be repeatedly supplied from the voltage application unit to the secondary winding during the discharge maintenance control period, and the secondary current flows to the spark plug each time. As a result, the secondary current is generated in the spark plug. Spark discharge can be maintained.
　第１８の開示は、第３，１４，１５のいずれか１つの開示において、前記点火プラグに流れる二次電流を検出する二次電流検出部を備え、前記点火制御回路は、前記放電維持制御を実施している期間中、前記二次電流検出部により検出された前記二次電流の絶対値が第一閾値よりも小さくなった場合に、前記第三スイッチング素子を閉状態に制御し、前記二次電流検出部により検出された前記二次電流の絶対値が前記第一閾値よりも大きく設定された第二閾値よりも大きくなった場合に、前記第三スイッチング素子を開状態に制御する。 In an eighteenth disclosure according to any one of the third, fourteenth, and fifteenth disclosures, the eighteenth disclosure includes a secondary current detection unit that detects a secondary current flowing through the spark plug, and the ignition control circuit performs the discharge maintenance control. When the absolute value of the secondary current detected by the secondary current detection unit becomes smaller than a first threshold during the implementation period, the third switching element is controlled to be closed, When the absolute value of the secondary current detected by the secondary current detection unit becomes larger than a second threshold value set larger than the first threshold value, the third switching element is controlled to be in an open state.
　第１９の開示は、第４又は７の開示において、前記点火プラグに流れる二次電流を検出する二次電流検出部を備え、前記点火制御回路は、前記放電維持制御を実施している期間中、前記二次電流検出部により検出された前記二次電流の絶対値が第一閾値よりも小さくなった場合に、前記第二スイッチング素子を閉状態に制御し、前記二次電流検出部により検出された前記二次電流の絶対値が前記第一閾値よりも大きく設定された第二閾値よりも大きくなった場合に、前記第二スイッチング素子を開状態に制御する。 A nineteenth disclosure is the disclosure of the fourth or seventh disclosure, further comprising a secondary current detection unit that detects a secondary current flowing through the spark plug, wherein the ignition control circuit performs the discharge maintenance control. When the absolute value of the secondary current detected by the secondary current detection unit is smaller than a first threshold, the second switching element is controlled to be closed and detected by the secondary current detection unit When the absolute value of the secondary current is larger than a second threshold set larger than the first threshold, the second switching element is controlled to be in an open state.
　電流還流経路を設けることで、第１８の開示に係る制御も第１９の開示に係る制御のどちらも、一次電流遮断時の二次電流の低下を緩やかにすることができるので、二次電流の絶対値を第一閾値から第二閾値までの範囲内に収めることが容易にできる。つまり、上述の二次電流でのフィードバック制御を行なうことで二次電流を所望とする範囲内に精度良く制御することができるとともに、二次電流の急激な変化を低減することができ、二次電流の急激な低下による放電火花の吹き消え現象などを低減することができる。 By providing the current return path, both the control according to the eighteenth disclosure and the control according to the nineteenth disclosure can moderate the decrease in the secondary current when the primary current is interrupted. The absolute value can be easily within the range from the first threshold value to the second threshold value. That is, by performing the feedback control with the secondary current described above, the secondary current can be accurately controlled within a desired range, and a sudden change in the secondary current can be reduced. It is possible to reduce the discharge spark blow-off phenomenon due to a sudden drop in current.
　第２０の開示は、第１乃至４のいずれか１つの開示において、前記第一スイッチング素子と、前記第二スイッチング素子と、前記第三スイッチング素子と、前記点火制御回路と、前記電流還流経路とは、前記点火コイルが収納されているケース内に収容される。 In a twentieth disclosure according to any one of the first to fourth disclosures, the first switching element, the second switching element, the third switching element, the ignition control circuit, and the current return path Is housed in a case in which the ignition coil is housed.
　点火プラグのうち点火コイルが収納されている空間内に、第一スイッチング素子と、第二スイッチング素子と、第三スイッチング素子と、点火制御回路と、電流還流部とが収容される。つまり、点火プラグのうち点火コイルが収納されている空間内に本内燃機関用点火システムを収容することができる。これにより、配線を削減することができ、また本内燃機関用点火システムの肥大化を抑えることができるので、車両への搭載性向上を図ることができる。 The first switching element, the second switching element, the third switching element, the ignition control circuit, and the current return unit are accommodated in a space in the ignition plug in which the ignition coil is accommodated. That is, the ignition system for the internal combustion engine can be accommodated in a space in the ignition plug in which the ignition coil is accommodated. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
　第２１の開示は、第５乃至７のいずれか１つの開示において、前記第一スイッチング素子と、前記第二スイッチング素子と、前記点火制御回路と、前記電流還流経路とは、前記点火コイルが収納されているケース内に収容される。 A twenty-first disclosure is the disclosure according to any one of the fifth to seventh aspects, wherein the first switching element, the second switching element, the ignition control circuit, and the current return path are accommodated in the ignition coil. Is contained in a case.
　点火プラグのうち点火コイルが収納されている空間内に、第一スイッチング素子と、第二スイッチング素子と、点火制御回路と、電流還流部とが収容される。つまり、点火プラグのうち点火コイルが収納されている空間内に本内燃機関用点火システムを収容することができる。これにより、配線を削減することができ、また本内燃機関用点火システムの肥大化を抑えることができるので、車両への搭載性向上を図ることができる。 The first switching element, the second switching element, the ignition control circuit, and the current return unit are accommodated in a space in the ignition plug in which the ignition coil is accommodated. That is, the ignition system for the internal combustion engine can be accommodated in a space in the ignition plug in which the ignition coil is accommodated. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
　第２２の開示は、第１０乃至１５のいずれか１つの開示において、前記第一スイッチング素子と、前記第三スイッチング素子と、前記点火制御回路と、前記電流還流経路とは、前記点火コイルが収納されているケース内に収容される。 According to a twenty-second disclosure, in any one of the tenth to fifteenth disclosures, the first switching element, the third switching element, the ignition control circuit, and the current return path are accommodated in the ignition coil. Is contained in a case.
　点火プラグのうち点火コイルが収納されている空間内に、第一スイッチング素子と、第三スイッチング素子と、点火制御回路と、電流還流部とが収容される。つまり、点火プラグのうち点火コイルが収納されている空間内に本内燃機関用点火システムを収容することができる。これにより、配線を削減することができ、また本内燃機関用点火システムの肥大化を抑えることができるので、車両への搭載性向上を図ることができる。 The first switching element, the third switching element, the ignition control circuit, and the current return unit are accommodated in a space in the ignition plug in which the ignition coil is accommodated. That is, the ignition system for the internal combustion engine can be accommodated in a space in the ignition plug in which the ignition coil is accommodated. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
　第２３の開示は、第１乃至２２のいずれか１つの開示において、前記第一スイッチング素子には、第五ダイオードが逆並列に接続されている。 According to a twenty-third disclosure, in any one of the first to twenty-second disclosures, a fifth diode is connected in antiparallel to the first switching element.
　第１乃至２２のいずれか１つの点火システムにおいて、仮に電流還流経路がない状態で放電維持制御を実施した場合、第二巻線へ流れる一次電流が第一スイッチング素子に逆並列に接続される第五ダイオードと、第一巻線と、を介して第二巻線から第二スイッチング素子へと流れる電流が還流することになる。この場合、還流する電流は第一巻線の影響を受けることでその電流の大きさが小さくなり、それに伴って二次コイルに生じる二次電流が小さくなるなど、その制御性が低下するおそれがある。この点、第１乃至２２のいずれか１つの開示に係る内燃機関用点火システムでは、電流還流経路が設けられているため、放電維持制御中に電流還流経路を介して第二巻線へと電流が第一巻線を介することなく還流することになる。これにより、点火プラグに流れる二次電流が急激に小さくなることを抑制することができるため、第一スイッチング素子に第五ダイオードが逆並列に接続される構成に対しても本点火システムは好適な構成といえる。 In the ignition system according to any one of the first to 22, when the discharge maintenance control is performed in a state where there is no current return path, the primary current flowing to the second winding is connected in reverse parallel to the first switching element. The current flowing from the second winding to the second switching element through the five diodes and the first winding is returned. In this case, the current flowing back is affected by the first winding, so that the magnitude of the current is reduced, and the secondary current generated in the secondary coil is reduced accordingly. is there. In this regard, in the ignition system for an internal combustion engine according to any one of the first to twenty-second disclosures, since a current return path is provided, a current is supplied to the second winding via the current return path during the discharge maintenance control. Will recirculate without going through the first winding. As a result, the secondary current flowing through the spark plug can be prevented from rapidly decreasing, and therefore the present ignition system is suitable for a configuration in which the fifth diode is connected in antiparallel to the first switching element. It can be said that it is a composition.
　第２４の開示では、第１乃至２３のいずれか１つの開示において、前記内燃機関は、多気筒内燃機関であり、前記点火制御回路は、前記内燃機関の各気筒に設けられており、前記放電維持制御において前記二次コイルに流れる電流を制御する電流制御信号を出力する制御装置を備え、前記制御装置には、前記電流制御信号を伝達する第一共通信号線及び第二共通信号線が接続されており、前記第一共通信号線から分岐した各信号線が、前記点火プラグによる点火が連続しない気筒の集まりである第一気筒群の各気筒の前記点火制御回路に接続され、前記第二共通信号線から分岐した各信号線が、前記点火プラグによる点火が連続しない気筒の集まりであり且つ前記第一気筒群に含まれない気筒の集まりである第二気筒群の各気筒の前記点火制御回路に接続されている。 In a twenty-fourth disclosure, in any one of the first to twenty-third disclosures, the internal combustion engine is a multi-cylinder internal combustion engine, and the ignition control circuit is provided in each cylinder of the internal combustion engine. A control device for outputting a current control signal for controlling a current flowing through the secondary coil in the maintenance control; and a first common signal line and a second common signal line for transmitting the current control signal are connected to the control device. Each signal line branched from the first common signal line is connected to the ignition control circuit of each cylinder of the first cylinder group, which is a group of cylinders in which ignition by the spark plug does not continue, Each of the signal lines branched from the common signal line is a group of cylinders that are not continuously ignited by the spark plug and is a group of cylinders not included in the first cylinder group. It is connected to the control circuit.
　内燃機関が多気筒内燃機関（例えば５気筒以上の内燃機関）である場合、二次コイルに流れる電流を制御する電流制御信号を全気筒で共通にすると、点火プラグによる点火が連続する気筒において電流制御信号の一部が重複するおそれがある。 When the internal combustion engine is a multi-cylinder internal combustion engine (for example, an internal combustion engine having five or more cylinders), if the current control signal for controlling the current flowing in the secondary coil is made common to all the cylinders, There is a possibility that part of the control signal overlaps.
　この点、上記構成では、制御装置により、放電維持制御において二次コイルに流れる電流を制御する電流制御信号が出力される。制御装置には、電流制御信号を伝達する第一共通信号線及び第二共通信号線が接続されている。第一共通信号線から分岐した各信号線が、点火プラグによる点火が連続しない気筒の集まりである第一気筒群の各気筒の点火制御回路に接続されている。このため、第一気筒群の気筒の点火は連続しておらず、第一気筒群の気筒に伝達される電流制御信号の一部が重複することを抑制することができる。また、第二共通信号線から分岐した各信号線が、点火プラグによる点火が連続しない気筒の集まりであり且つ第一気筒群に含まれない気筒の集まりである第二気筒群の各気筒の点火制御回路に接続されている。このため、第二気筒群の気筒の点火は連続しておらず、第二気筒群の気筒に伝達される電流制御信号の一部が重複することを抑制することができる。したがって、内燃機関が多気筒内燃機関であっても、二次コイルに流れる電流を電流制御信号により制御することができる。 In this regard, in the above configuration, the control device outputs a current control signal for controlling the current flowing in the secondary coil in the discharge maintenance control. A first common signal line and a second common signal line for transmitting a current control signal are connected to the control device. Each signal line branched from the first common signal line is connected to the ignition control circuit of each cylinder of the first cylinder group, which is a group of cylinders that are not continuously ignited by the spark plug. For this reason, ignition of the cylinders of the first cylinder group is not continuous, and it is possible to suppress a part of the current control signal transmitted to the cylinders of the first cylinder group from overlapping. Further, each of the signal lines branched from the second common signal line is a group of cylinders that are not continuously ignited by the spark plug and is a group of cylinders not included in the first cylinder group. Connected to the control circuit. For this reason, ignition of the cylinders of the second cylinder group is not continuous, and it is possible to suppress a part of the current control signal transmitted to the cylinders of the second cylinder group from overlapping. Therefore, even if the internal combustion engine is a multi-cylinder internal combustion engine, the current flowing through the secondary coil can be controlled by the current control signal.
　具体的には、第２５の開示では、前記第一気筒群に含まれる２つの気筒で相前後して前記点火が行われる間に、前記第二気筒群に含まれる１つの気筒で前記点火が行われる。 Specifically, in the twenty-fifth disclosure, the ignition is performed in one cylinder included in the second cylinder group while the ignition is performed in succession in two cylinders included in the first cylinder group. Done.
　第一気筒群に含まれる２つの気筒で相前後して点火が行われる間に、第二気筒群に含まれる１つの気筒で点火が行われることで、第一気筒群の気筒の点火が連続せず、且つ第二気筒群の気筒の点火が連続しないようにすることができる。 While ignition is performed consecutively in two cylinders included in the first cylinder group, ignition is performed in one cylinder included in the second cylinder group, so that the ignition of the cylinders in the first cylinder group is continuous. And the ignition of the cylinders of the second cylinder group can be prevented from continuing.
　本開示についての上記目的およびその他の目的、特徴や利点は、添付の図面を参照しながら下記の詳細な記述により、より明確になる。その図面は、
図１は、第一実施形態に係る点火システムの概略構成図であり、 図２は、放電開始制御が開始された場合の一次電流の流れを示した図であり、 図３は、放電維持制御が実施された場合の一次電流の流れを示した図であり、 図４は、電流還流経路が設けられていない点火システムにおいて放電維持制御を実施した場合の一次電流及び二次電流の変動を示した図であり、 図５は、放電維持制御が実施された場合の還流する一次電流の流れを示した図であり、 図６は、二次電流を所望の範囲に制御する内容を簡易的に示した図であり、 図７は、本実施形態に係る放電制御の動作を示すタイムチャートであり、 図８は、内燃機関において特に点火コイルが収容されているケース周辺を示した概略構成図であり、 図９は、別例に係る放電制御の動作を示すタイムチャートであり、 図１０は、図１の構成に適用される第三ダイオードの設置場所の別例を示した図であり、 図１１は、第一実施形態に係る点火システムの別例を示す概略構成図であり、 図１２は、点火信号及びエネルギ投入信号による二次電流の指令値の設定を示した図であり、 図１３は、点火信号及びエネルギ投入信号による二次電流の指令値の設定を示した図であり、 図１４は、点火信号及びエネルギ投入信号による二次電流の指令値の設定を示した図であり、 図１５は、図１１に示す別例に係る放電制御の動作を示すタイムチャートであり、 図１６は、第一実施形態に係る点火システムの別例を示す概略構成図であり、 図１７は、第一実施形態に係る点火システムの別例を示す概略構成図であり、 図１８は、図１７に示す別例に係る放電制御の動作を示すタイムチャートであり、 図１９は、第一実施形態に係る点火システムの別例を示す概略構成図であり、 図２０は、第二実施形態に係る点火システムの概略構成図であり、 図２１は、第二実施形態に係る放電制御の動作を示すタイムチャートであり、 図２２は、第二実施形態の構成に適用される第三ダイオードの設置場所の別例を示した図であり、 図２３は、第二実施形態に係る点火システムの別例を示す概略構成図であり、 図２４は、図２３に示す別例に係る放電制御の動作を示すタイムチャートであり、 図２５は、図２３に示す別例における第三ダイオードの設置場所の変更例を示した図であり、 図２６は、第三実施形態に係る点火システムの概略構成図であり、 図２７は、第三実施形態に係る放電制御の動作を示すタイムチャートであり、 図２８は、第三実施形態に適用される第三ダイオードの設置場所の別例を示した図であり、 図２９は、第三実施形態に係る点火システムの別例を示す概略構成図であり、 図３０は、図２９に示す別例に係る放電制御の動作を示すタイムチャートであり、 図３１は、第三実施形態に適用される別例に係る放電発生制御により生じる二次電圧と、従来の放電発生制御により生じる二次電圧と、を比較した図であり、 図３２は、４気筒エンジンに適用されるエンジンＥＣＵと各点火制御回路との接続を示す概略構成図であり、 図３３は、比較例の点火信号とエネルギ投入信号とを示すタイムチャートであり、 図３４は、６気筒エンジンに適用されるエンジンＥＣＵと各点火制御回路との接続を示す概略構成図であり、 図３５は、図３４に示す実施形態の点火信号とエネルギ投入信号とを示すタイムチャートであり、 図３６は、点火信号のみによる放電制御の動作を示すタイムチャートであり、 図３７は、図３６の放電制御を実行する点火システムの概略構成図である。 The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is a schematic configuration diagram of an ignition system according to the first embodiment. FIG. 2 is a diagram showing the flow of the primary current when the discharge start control is started, FIG. 3 is a diagram showing the flow of the primary current when the discharge maintenance control is performed, FIG. 4 is a diagram showing fluctuations in the primary current and the secondary current when the discharge maintenance control is performed in an ignition system in which no current return path is provided, FIG. 5 is a diagram showing the flow of the primary current that circulates when the discharge maintenance control is performed, FIG. 6 is a diagram simply showing the content of controlling the secondary current to a desired range, FIG. 7 is a time chart showing the operation of the discharge control according to the present embodiment. FIG. 8 is a schematic configuration diagram showing the periphery of a case in which an ignition coil is housed in an internal combustion engine, FIG. 9 is a time chart showing an operation of discharge control according to another example. FIG. 10 is a diagram showing another example of the installation location of the third diode applied to the configuration of FIG. FIG. 11 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment. FIG. 12 is a diagram showing the setting of the command value of the secondary current by the ignition signal and the energy input signal, FIG. 13 is a diagram showing the setting of the command value of the secondary current by the ignition signal and the energy input signal, FIG. 14 is a diagram showing the setting of the command value of the secondary current by the ignition signal and the energy input signal, FIG. 15 is a time chart showing the operation of the discharge control according to another example shown in FIG. FIG. 16 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment, FIG. 17 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment, FIG. 18 is a time chart showing an operation of discharge control according to another example shown in FIG. FIG. 19 is a schematic configuration diagram illustrating another example of the ignition system according to the first embodiment, FIG. 20 is a schematic configuration diagram of an ignition system according to the second embodiment. FIG. 21 is a time chart showing the operation of the discharge control according to the second embodiment. FIG. 22 is a diagram showing another example of the installation location of the third diode applied to the configuration of the second embodiment, FIG. 23 is a schematic configuration diagram illustrating another example of the ignition system according to the second embodiment, FIG. 24 is a time chart showing the operation of discharge control according to another example shown in FIG. FIG. 25 is a diagram showing an example of changing the installation location of the third diode in another example shown in FIG. FIG. 26 is a schematic configuration diagram of an ignition system according to a third embodiment. FIG. 27 is a time chart showing the operation of the discharge control according to the third embodiment. FIG. 28 is a diagram showing another example of the installation location of the third diode applied to the third embodiment, FIG. 29 is a schematic configuration diagram illustrating another example of the ignition system according to the third embodiment, FIG. 30 is a time chart showing an operation of discharge control according to another example shown in FIG. FIG. 31 is a diagram comparing a secondary voltage generated by discharge generation control according to another example applied to the third embodiment and a secondary voltage generated by conventional discharge generation control, FIG. 32 is a schematic configuration diagram showing a connection between an engine ECU applied to a four-cylinder engine and each ignition control circuit, FIG. 33 is a time chart showing an ignition signal and an energy input signal of a comparative example, FIG. 34 is a schematic configuration diagram showing a connection between an engine ECU applied to a 6-cylinder engine and each ignition control circuit. FIG. 35 is a time chart showing the ignition signal and the energy input signal of the embodiment shown in FIG. FIG. 36 is a time chart showing the operation of discharge control based only on the ignition signal, FIG. 37 is a schematic configuration diagram of an ignition system that performs the discharge control of FIG.
　＜第１実施形態＞
　第一実施形態を、図面を参照して説明する。本点火システム１０は、内燃機関（以下、エンジンと呼称）６０に搭載されるものである（図８参照）。点火システム１０の構成を、図１を参照して説明する。点火システム１０は、点火プラグ２０と、点火コイル１１と、第三スイッチング素子１４と、第一スイッチング素子１５と、第二スイッチング素子１６と、電源部（電圧印加部に該当）１７と、点火制御回路３０と、が設けられている。 <First Embodiment>
A first embodiment will be described with reference to the drawings. The ignition system 10 is mounted on an internal combustion engine (hereinafter referred to as an engine) 60 (see FIG. 8). The configuration of the ignition system 10 will be described with reference to FIG. The ignition system 10 includes an ignition plug 20, an ignition coil 11, a third switching element 14, a first switching element 15, a second switching element 16, a power supply unit (corresponding to a voltage application unit) 17, an ignition control A circuit 30 is provided.
　点火コイル１１は、一次コイル１２、二次コイル１３及び鉄心２３を備えている。一次コイル１２を成す巻線の途中には中間タップ１２Ａが設けられており、中間タップ１２Ａは、第三スイッチング素子１４を介して電源部１７に接続されている。このため、第三スイッチング素子１４が閉状態となった場合には、電源部１７から所定の電圧が中間タップ１２Ａに印加されることになる。また、一次コイル１２を成す巻線のうち中間タップ１２Ａから一端までの巻数がより多い側の巻線である第一巻線１２Ｂ側の一端は、第一スイッチング素子１５に接続されている。一次コイル１２を成す巻線のうち中間タップ１２Ａから一端までの巻数がより少ない側の巻線である第二巻線１２Ｃ側の一端は、第三ダイオード１９を介して第二スイッチング素子１６に接続されている。 The ignition coil 11 includes a primary coil 12, a secondary coil 13, and an iron core 23. An intermediate tap 12 </ b> A is provided in the middle of the winding forming the primary coil 12, and the intermediate tap 12 </ b> A is connected to the power supply unit 17 via the third switching element 14. Therefore, when the third switching element 14 is closed, a predetermined voltage is applied from the power supply unit 17 to the intermediate tap 12A. In addition, one end on the first winding 12 </ b> B side, which is a winding having a larger number of turns from the intermediate tap 12 </ b> A to one end among the windings forming the primary coil 12, is connected to the first switching element 15. One end on the second winding 12 </ b> C side, which is the winding having the smaller number of turns from the intermediate tap 12 </ b> A to one end among the windings forming the primary coil 12, is connected to the second switching element 16 via the third diode 19. Has been.
　第三スイッチング素子１４は、ＭＯＳＦＥＴ（Ｍｅｔａｌ　Ｏｘｉｄｅ　Ｓｅｍｉｃｏｎｄｕｃｔｏｒ　Ｆｉｅｌｄ　Ｅｆｆｅｃｔ　Ｔｒａｎｓｉｓｔｏｒ）であって、第三制御端子１４Ｇと、第三電源側端子１４Ｄと、第三接地側端子１４Ｓと、を有している。この第三スイッチング素子１４は、第三制御端子１４Ｇに入力された第三制御信号に基づいて、第三電源側端子１４Ｄと第三接地側端子１４Ｓとの間の通電のオンオフを制御するように構成されている。本実施形態において、第三接地側端子１４Ｓは中間タップ１２Ａに接続されており、第三電源側端子１４Ｄは電源部１７に接続されている。 The third switching element 14 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and has a third control terminal 14G, a third power supply side terminal 14D, and a third ground side terminal 14S. The third switching element 14 controls on / off of energization between the third power supply side terminal 14D and the third ground side terminal 14S based on the third control signal input to the third control terminal 14G. It is configured. In the present embodiment, the third ground side terminal 14 </ b> S is connected to the intermediate tap 12 </ b> A, and the third power supply side terminal 14 </ b> D is connected to the power supply unit 17.
　第一スイッチング素子１５は、ＭＯＳゲート構造トランジスタであるＩＧＢＴ（Ｉｎｓｕｌａｔｅｄ　Ｇａｔｅ　Ｂｉｐｏｌａｒ　Ｔｒａｎｓｉｓｔｏｒ）であって、第一制御端子１５Ｇと、第一電源側端子１５Ｃと、第一接地側端子１５Ｅと、を有している。この第一スイッチング素子１５は、第一制御端子１５Ｇに入力された第一制御信号に基づいて、第一電源側端子１５Ｃと第一接地側端子１５Ｅとの間の通電のオンオフを制御するように構成されている。本実施形態において、第一電源側端子１５Ｃは第一巻線１２Ｂに接続されている。また、第一接地側端子１５Ｅは接地されている。 The first switching element 15 is an IGBT (Insulated Gate Bipolar Transistor) that is a MOS gate structure transistor, and includes a first control terminal 15G, a first power supply side terminal 15C, and a first ground side terminal 15E. ing. The first switching element 15 controls on / off of energization between the first power supply side terminal 15C and the first ground side terminal 15E based on the first control signal input to the first control terminal 15G. It is configured. In the present embodiment, the first power supply side terminal 15C is connected to the first winding 12B. The first ground side terminal 15E is grounded.
　第二スイッチング素子１６は、ＭＯＳＦＥＴであって、第二制御端子１６Ｇと、第二電源側端子１６Ｄと、第二接地側端子１６Ｓと、を有している。この第二スイッチング素子１６は、第二制御端子１６Ｇに入力された第二制御信号に基づいて、第二電源側端子１６Ｄと第二接地側端子１６Ｓとの間の通電のオンオフを制御するように構成されている。本実施形態において、第二電源側端子１６Ｄは第三ダイオード１９を介して第二巻線１２Ｃに接続されており、第二接地側端子１６Ｓは接地されている。第三ダイオード１９についての詳細は、後述する。 The second switching element 16 is a MOSFET, and has a second control terminal 16G, a second power supply side terminal 16D, and a second ground side terminal 16S. The second switching element 16 controls on / off of energization between the second power supply side terminal 16D and the second ground side terminal 16S based on the second control signal input to the second control terminal 16G. It is configured. In the present embodiment, the second power supply side terminal 16D is connected to the second winding 12C via the third diode 19, and the second ground side terminal 16S is grounded. Details of the third diode 19 will be described later.
　中間タップ１２Ａは、第三スイッチング素子１４に接続されるほか、電流還流経路Ｌ１とも接続されている。電流還流経路Ｌ１は、第一ダイオード１８を備えている。第一ダイオード１８のカソード側は中間タップ１２Ａに接続されており、第一ダイオード１８のアノード側は接地されている。 The intermediate tap 12A is connected to the third switching element 14 and also to the current return path L1. The current return path L1 includes a first diode 18. The cathode side of the first diode 18 is connected to the intermediate tap 12A, and the anode side of the first diode 18 is grounded.
　二次コイル１３の第一端は、一次コイル通電時の飛び火防止ダイオード２１（以降、防止ダイオードと呼称）を介して、電流検出用経路Ｌ２と接続されている。この電流検出用経路Ｌ２には、二次電流検出用の抵抗体２２が設けられている。抵抗体２２の第一端は防止ダイオード２１を介して二次コイル１３の第一端と接続され、抵抗体２２の第二端は接地側に接続されている。防止ダイオード２１は、第一巻線１２Ｂに通電するときに発生する、接地側から抵抗体２２を介して二次コイル１３における第二端側に向かう方向の電流の通流を防止する。これにより一次コイル１２に通電するときに発生する一次コイル１２のオン電圧での飛び火を防止するとともに、二次電流（放電電流）Ｉ２を点火プラグ２０から二次コイル１３に向かう方向に規定すべく、そのアノードが二次コイル１３における第一端側に接続されている。 The first end of the secondary coil 13 is connected to a current detection path L2 through a spark prevention diode 21 (hereinafter referred to as a prevention diode) when the primary coil is energized. The current detection path L2 is provided with a resistor 22 for detecting a secondary current. The first end of the resistor 22 is connected to the first end of the secondary coil 13 via the prevention diode 21, and the second end of the resistor 22 is connected to the ground side. The prevention diode 21 prevents a current from flowing from the ground side to the second end side of the secondary coil 13 through the resistor 22 that is generated when the first winding 12B is energized. As a result, it is possible to prevent the primary coil 12 from being ignited at the on-voltage when the primary coil 12 is energized, and to define the secondary current (discharge current) I2 in the direction from the spark plug 20 toward the secondary coil 13. The anode is connected to the first end side of the secondary coil 13.
　点火制御回路３０は、図示しないエンジンＥＣＵ（制御装置）より出力された点火信号ＩＧｔを受信するように、エンジンＥＣＵに接続されている。かかる点火信号ＩＧｔは、エンジン６０の燃焼室内におけるガスの状態及び必要とされるエンジン６０の出力に応じた、最適な点火時期及び二次電流（放電電流）を規定するものである。また、点火制御回路３０は、第三スイッチング素子１４、第一スイッチング素子１５、及び第二スイッチング素子１６の開閉動作を制御するように、第三制御端子１４Ｇ、第一制御端子１５Ｇ及び第二制御端子１６Ｇに接続されている。 The ignition control circuit 30 is connected to the engine ECU so as to receive an ignition signal IGt output from an engine ECU (control device) (not shown). The ignition signal IGt defines an optimal ignition timing and secondary current (discharge current) according to the state of gas in the combustion chamber of the engine 60 and the required output of the engine 60. The ignition control circuit 30 also controls the third control terminal 14G, the first control terminal 15G, and the second control so as to control the opening / closing operation of the third switching element 14, the first switching element 15, and the second switching element 16. It is connected to the terminal 16G.
　点火制御回路３０は、エンジンＥＣＵから受信した点火信号ＩＧｔに基づいて、第三スイッチング素子１４が有する第三制御端子１４Ｇと、第一スイッチング素子１５が有する第一制御端子１５Ｇと、第二スイッチング素子１６が有する第二制御端子１６Ｇと、のそれぞれに対して開閉制御を行なうための駆動信号ＩＧ１，ＩＧ２，ＩＧ３を出力する。 Based on the ignition signal IGt received from the engine ECU, the ignition control circuit 30 includes a third control terminal 14G included in the third switching element 14, a first control terminal 15G included in the first switching element 15, and a second switching element. Drive signals IG1, IG2, and IG3 for performing open / close control on each of the second control terminals 16G of 16 are output.
　これにより、まず電源部１７から第一巻線１２Ｂへと流れる経路（図２参照）を形成し、その上で第一巻線１２Ｂに流れる一次電流Ｉ１の導通と遮断を制御することで点火プラグ２０に火花放電を生じさせる放電開始制御を実施する。放電開始制御の実施後、電源部１７から第二巻線１２Ｃへと流れる経路（図３参照）を形成し、その上で第二巻線１２Ｃに流れる一次電流Ｉ１の導通と遮断を制御することで点火プラグ２０に生じている火花放電を維持させる放電維持制御を実施する。このとき、電流検出用経路Ｌ２に流れる二次電流Ｉ２を検出することから、電流検出用経路Ｌ２と、点火制御回路３０とは、二次電流検出部に該当する。 Thus, first, a path (see FIG. 2) that flows from the power supply unit 17 to the first winding 12B is formed, and then the ignition plug is controlled by controlling the conduction and blocking of the primary current I1 that flows to the first winding 12B. Discharge start control for causing a spark discharge at 20 is performed. After the discharge start control is performed, a path (see FIG. 3) that flows from the power supply unit 17 to the second winding 12C is formed, and then the conduction and interruption of the primary current I1 that flows to the second winding 12C is controlled. The discharge maintenance control for maintaining the spark discharge generated in the spark plug 20 is performed. At this time, since the secondary current I2 flowing through the current detection path L2 is detected, the current detection path L2 and the ignition control circuit 30 correspond to a secondary current detection unit.
　放電開始制御の制御内容を説明する。放電開始制御を実施している期間中、第二スイッチング素子１６を常に開状態に制御する。その上で、第三スイッチング素子１４及び第一スイッチング素子１５を閉状態に制御することで、図２に示されるように、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れる。そして、第一所定時間の経過後に第一スイッチング素子１５を開状態に制御する。これにより、電源部１７から第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０の火花ギャップ部の気体が絶縁破壊することで、点火プラグ２０で火花放電が生じる。 The details of the discharge start control will be described. During the period when the discharge start control is performed, the second switching element 16 is always controlled to be in the open state. Then, by controlling the third switching element 14 and the first switching element 15 to be closed, a primary current I1 flows from the power supply unit 17 to the first winding 12B as shown in FIG. Then, the first switching element 15 is controlled to be in an open state after the first predetermined time has elapsed. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
　ここで、第三ダイオード１９が設けられていない状態で、上記の放電開始制御を実施した場合を想定する。この場合、電源部１７から第一巻線１２Ｂに一次電流Ｉ１が流れる一方で、第二スイッチング素子１６から第二巻線１２Ｃを介して電源部１７へと流れる電流が発生する場合がある。つまり、第一巻線１２Ｂと第二巻線１２Ｃとで磁気回路が構成されていたり、漏洩磁束が鎖交したりすることにより、第一スイッチング素子１５で第一巻線１２Ｂに流れる一次電流Ｉ１を遮断したときに、第二巻線１２Ｃに負の電圧が発生し、接地側から電源部１７へと電流が流れる場合がある。仮に第二スイッチング素子１６から第二巻線１２Ｃを介して電源部１７へと流れる電流が発生した場合、発生した前記電流と、電源部１７から第一巻線１２Ｂに流れる一次電流Ｉ１とが互いに相殺されることで、一次電流Ｉ１は相殺された分だけ小さくなることになる。この対策として、カソード側が第二スイッチング素子１６に接続されており、アノード側が第二巻線１２Ｃにおける第二スイッチング素子１６側の端部に接続されている第三ダイオード１９を設けている。これにより、第二スイッチング素子１６から第二巻線１２Ｃを介して電源部１７へと電流が流れることを抑制する事が可能となり放電開始制御の発生電圧の低下を防止することができる。 Here, it is assumed that the above discharge start control is performed in a state where the third diode 19 is not provided. In this case, while the primary current I1 flows from the power supply unit 17 to the first winding 12B, a current flowing from the second switching element 16 to the power supply unit 17 through the second winding 12C may be generated. That is, when the first winding 12B and the second winding 12C form a magnetic circuit, or the leakage magnetic flux is linked, the primary current I1 that flows in the first winding 12B by the first switching element 15 When the circuit is interrupted, a negative voltage is generated in the second winding 12 </ b> C, and a current may flow from the ground side to the power supply unit 17. If a current flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C is generated, the generated current and the primary current I1 flowing from the power supply unit 17 to the first winding 12B are mutually connected. By canceling out, the primary current I1 becomes smaller by the offset. As a countermeasure, a third diode 19 having a cathode connected to the second switching element 16 and an anode connected to an end of the second winding 12C on the second switching element 16 side is provided. Thereby, it is possible to suppress a current from flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C, and it is possible to prevent a decrease in the voltage generated in the discharge start control.
　放電開始制御を実施後、放電維持制御を実施する。放電維持制御を実施している期間中は、第一スイッチング素子１５を常に開状態に制御する。この状態で、第三スイッチング素子１４及び第二スイッチング素子１６を閉状態に制御することで、図３に示されるように、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れることになる。そして、第三スイッチング素子１４を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断する。 After the discharge start control is performed, discharge maintenance control is performed. During the period in which the discharge maintenance control is performed, the first switching element 15 is always controlled to be in the open state. In this state, by controlling the third switching element 14 and the second switching element 16 to be closed, the primary current I1 flows from the power supply unit 17 to the second winding 12C as shown in FIG. Become. Then, by controlling the third switching element 14 to the open state, the conduction of the primary current I1 flowing from the power supply unit 17 to the second winding 12C is interrupted.
　仮に、点火システム１０に電流還流経路Ｌ１が設けられていなかった場合、第三スイッチング素子１４を開状態に制御することで第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断すると、第二巻線１２Ｃに流れていた一次電流Ｉ１が遮断され、一次電流Ｉ１がステップ的に０になる。その結果、図４に示されるように、第三スイッチング素子１４が開状態に制御されるたび二次電流Ｉ２の絶対値もステップ的にかつ急激に小さくなり、それに伴って例えば、放電火花が気流などで吹き消されて点火プラグ２０に生じた火花放電が維持できなくなるおそれがある。 If the current return path L1 is not provided in the ignition system 10, if the conduction of the primary current I1 flowing to the second winding 12C is interrupted by controlling the third switching element 14 to be open, The primary current I1 flowing through the winding 12C is cut off, and the primary current I1 becomes zero stepwise. As a result, as shown in FIG. 4, every time the third switching element 14 is controlled to open, the absolute value of the secondary current I2 also decreases stepwise and abruptly. There is a possibility that the spark discharge generated in the spark plug 20 by being blown out by the above cannot be maintained.
　この点、本点火システム１０には電流還流経路Ｌ１が設けられているため、第三スイッチング素子１４を開状態に制御すると、図５に示されるように、第三スイッチング素子１４で遮断したあとも、第二巻線１２Ｃのインダクタンスにより電流還流経路Ｌ１を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなる。これにより一次電流Ｉ１は緩やかに減衰し、点火プラグ２０に流れる二次電流Ｉ２の絶対値がステップ的に、かつ急激に小さくなることを抑制することができる。 In this respect, since the current return path L1 is provided in the ignition system 10, when the third switching element 14 is controlled to be in an open state, as shown in FIG. The primary current I1 flows back to the second winding 12C via the current return path L1 due to the inductance of the second winding 12C. As a result, the primary current I1 is gradually attenuated, and the absolute value of the secondary current I2 flowing through the spark plug 20 can be suppressed from decreasing stepwise and rapidly.
　加えて、電流還流経路Ｌ１が中間タップ１２Ａに接続されることで、放電維持制御を実施している期間中、電流還流経路Ｌ１を流れる一次電流Ｉ１は第一巻線１２Ｂを流れず、第二巻線１２Ｃに直接流れることとなる。これにより、第一巻線１２Ｂの影響を受けることがなくなるため、一次電流Ｉ１を精度よく、かつ応答性よく制御することが可能となる。 In addition, since the current return path L1 is connected to the intermediate tap 12A, the primary current I1 flowing through the current return path L1 does not flow through the first winding 12B during the period when the discharge maintenance control is performed, It will flow directly to the winding 12C. As a result, the influence of the first winding 12B is eliminated, and the primary current I1 can be controlled with high accuracy and responsiveness.
　ところで、放電維持制御を実施している期間中、電源部１７から第二巻線１２Ｃに一次電流Ｉ１が繰り返し流れることになるが、二次コイル１３の巻数を第二巻線１２Ｃで割った値である巻数比の設定次第では、第二巻線１２Ｃに印加する必要のある電圧が、電源部１７が印加できる所定の電圧よりも高くなるおそれがある。この場合、電源部１７から第二巻線１２Ｃに一次電流Ｉ１を流すことができず、その結果として点火プラグ２０で生じている火花放電を維持することができない懸念がある。 By the way, the primary current I1 repeatedly flows from the power supply unit 17 to the second winding 12C during the period in which the discharge maintenance control is performed. The value obtained by dividing the number of turns of the secondary coil 13 by the second winding 12C. Depending on the setting of the turn ratio, the voltage that needs to be applied to the second winding 12C may be higher than a predetermined voltage that can be applied by the power supply unit 17. In this case, there is a concern that the primary current I1 cannot flow from the power supply unit 17 to the second winding 12C, and as a result, the spark discharge generated in the spark plug 20 cannot be maintained.
　この対策として、本実施形態では、電源部１７が印加する所定の電圧で放電維持電圧を割った値としての電圧比よりも、上記巻数比が大きくなるように点火コイル１１が構成される。放電維持電圧は、放電発生制御により点火プラグ２０に発生させた火花放電が維持されているときの電圧である。 As a countermeasure, in this embodiment, the ignition coil 11 is configured such that the turn ratio is larger than the voltage ratio obtained by dividing the discharge sustain voltage by a predetermined voltage applied by the power supply unit 17. The discharge sustain voltage is a voltage when the spark discharge generated in the spark plug 20 by the discharge generation control is maintained.
　放電維持電圧はエンジンＥＣＵの運転環境によって変化するが、平均すると２～３ｋＶの範囲内で点火プラグ２０に発生させた火花放電を維持できていることから、放電維持電圧は２～３ｋＶの範囲内で固定の値として設定される。つまり、電圧比は固定値となるため、第二巻線１２Ｃの巻数が少なくなるほど、巻数比は大きくなることになる。これにより、電圧比よりも巻数比が大きくなるように第二巻線１２Ｃの巻数を少なくすることで、放電維持制御を実施している期間中において、第二巻線１２Ｃに印加する必要のある電圧が、電源部１７が印加できる電圧よりも低くなるように設定することができる。これにより、放電維持制御を実施している期間中、第二巻線１２Ｃに電源部１７から一次電流Ｉ１を繰り返し流すことができ、そのたび点火プラグ２０に二次電流Ｉ２が流れ、その結果として点火プラグ２０に発生している火花放電を維持することができる。ひいては、電源部１７にＤＣ－ＤＣコンバータ等の電圧昇圧回路を設ける必要がなく、点火システム１０の簡素化を図ることが出来る。 Although the discharge sustaining voltage varies depending on the operating environment of the engine ECU, since the spark discharge generated in the spark plug 20 can be maintained within a range of 2 to 3 kV on average, the discharge maintaining voltage is within a range of 2 to 3 kV. Is set as a fixed value. That is, since the voltage ratio is a fixed value, the turn ratio increases as the number of turns of the second winding 12C decreases. As a result, the number of turns of the second winding 12C is reduced so that the turns ratio is larger than the voltage ratio, so that it is necessary to apply the second winding 12C to the second winding 12C during the period during which the discharge maintenance control is performed. The voltage can be set to be lower than the voltage that can be applied by the power supply unit 17. As a result, during the period when the discharge maintenance control is performed, the primary current I1 can be repeatedly supplied from the power supply unit 17 to the second winding 12C, and the secondary current I2 flows through the spark plug 20 each time. The spark discharge generated in the spark plug 20 can be maintained. As a result, it is not necessary to provide a voltage booster circuit such as a DC-DC converter in the power supply unit 17, and the ignition system 10 can be simplified.
　本実施形態では、放電維持制御を実施している期間中、点火制御回路３０は電流検出用経路Ｌ２に流れる二次電流Ｉ２を逐次検出している、そして、検出した二次電流Ｉ２に基づいて図６に示す制御を実施する。図６において、「二次電流Ｉ２」は、電流検出用経路Ｌ２に流れる二次電流Ｉ２の値を表すものである。「第三制御信号」は、第三スイッチング素子１４の第三制御端子１４Ｇへ第三制御信号が出力されたか否かをハイ／ローで表すものである。具体的には、第三スイッチング素子１４の第三制御端子１４Ｇへ第三制御信号が出力された場合に（図６の「第三制御信号」においてハイとなった場合に）、第三スイッチング素子１４は閉状態に制御される。また、第三スイッチング素子１４の第三制御端子１４Ｇへ第三制御信号が出力されていない場合に（図２の「第三制御信号」においてローとなった場合に）、第三スイッチング素子１４は開状態に制御される。「第二制御信号」は、第二スイッチング素子１６の第二制御端子１６Ｇへ第二制御信号が出力されたか否かをハイ／ローで表すものである。 In the present embodiment, the ignition control circuit 30 sequentially detects the secondary current I2 flowing through the current detection path L2 during the period in which the discharge maintenance control is performed, and based on the detected secondary current I2. The control shown in FIG. 6 is performed. In FIG. 6, “secondary current I2” represents the value of the secondary current I2 flowing through the current detection path L2. The “third control signal” indicates whether the third control signal is output to the third control terminal 14G of the third switching element 14 by high / low. Specifically, when the third control signal is output to the third control terminal 14G of the third switching element 14 (when the third control signal becomes high in FIG. 6), the third switching element 14 is controlled to be closed. In addition, when the third control signal is not output to the third control terminal 14G of the third switching element 14 (when it becomes low in the “third control signal” in FIG. 2), the third switching element 14 Controlled to open state. The “second control signal” indicates whether the second control signal is output to the second control terminal 16G of the second switching element 16 by high / low.
　図６に示すように、放電維持制御を実施している期間中検出した二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、第三スイッチング素子１４及び第二スイッチング素子１６を閉状態に制御する。これにより、第二巻線１２Ｃに電源部１７から一次電流Ｉ１を流すことができ、それに伴って点火プラグ２０に流れる二次電流Ｉ２の絶対値が大きくなる。検出した二次電流Ｉ２の絶対値が第一閾値よりも大きく設定された第二閾値よりも大きくなった場合には、第三スイッチング素子１４を開状態に制御する。これにより、電源部１７から第二巻線１２Ｃに流れる一次電流Ｉ１が遮断され、点火プラグ２０に流れる二次電流Ｉ２の絶対値が小さくなる。一次電流Ｉ１を第三スイッチング素子１４で遮断したときに第二巻線１２Ｃの一次電流Ｉ１は、電流還流経路Ｌ１で還流しながら流れ、小さくなっていくので二次電流Ｉ２は緩やかに減衰していく。このように、上記制御を実施することで、二次電流Ｉ２は緩やかな変化とすることができ、第一閾値から第二閾値までの範囲内に容易に収めることができる。また急激な二次電流Ｉ２の低下を防止できるので、放電火花の吹き消えを防止することが可能な放電制御を実施することができる。 As shown in FIG. 6, when the absolute value of the secondary current I2 detected during the period during which the sustaining control is performed becomes smaller than the first threshold value, the third switching element 14 and the second switching element 16 Is controlled to be closed. As a result, the primary current I1 can flow from the power supply unit 17 to the second winding 12C, and the absolute value of the secondary current I2 flowing to the spark plug 20 increases accordingly. When the detected absolute value of the secondary current I2 becomes larger than the second threshold value set larger than the first threshold value, the third switching element 14 is controlled to be in the open state. As a result, the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the absolute value of the secondary current I2 flowing through the spark plug 20 becomes small. When the primary current I1 is cut off by the third switching element 14, the primary current I1 of the second winding 12C flows while flowing back through the current return path L1 and becomes smaller, so the secondary current I2 is gradually attenuated. Go. As described above, by performing the above control, the secondary current I2 can be gradually changed, and can be easily within the range from the first threshold value to the second threshold value. In addition, since the sudden decrease in the secondary current I2 can be prevented, discharge control capable of preventing the discharge spark from being blown out can be performed.
　次に、図７を参照して、本実施形態にかかる放電制御の態様を説明する。 Next, with reference to FIG. 7, a mode of discharge control according to the present embodiment will be described.
　図７において、「第一巻線を流れる一次電流Ｉ１」は、第一巻線１２Ｂを流れる一次電流Ｉ１を表すものである。同様に「第二巻線を流れる一次電流Ｉ１」は、第二巻線１２Ｃを流れる一次電流Ｉ１を表すものである。また、「二次電圧Ｖ２」は、点火プラグ２０に印加される二次電圧Ｖ２の値を表すものである。「第一制御信号」は、第一スイッチング素子１５の第一制御端子１５Ｇへ第一制御信号が出力されたか否かをハイ／ローで表すものである。 7, “Primary current I1 flowing through the first winding” represents the primary current I1 flowing through the first winding 12B. Similarly, the “primary current I1 flowing through the second winding” represents the primary current I1 flowing through the second winding 12C. Further, “secondary voltage V2” represents the value of the secondary voltage V2 applied to the spark plug 20. The “first control signal” indicates whether the first control signal is output to the first control terminal 15G of the first switching element 15 by high / low.
　エンジンＥＣＵより出力された点火信号ＩＧｔに基づいて、点火制御回路３０により放電発生制御が実施される。放電発生制御では、第三制御信号が第三スイッチング素子１４の第三制御端子１４Ｇに送信されるとともに、第一制御信号が第一スイッチング素子１５の第一制御端子１５Ｇに送信される（時間ｔ１参照）。これにより、第二スイッチング素子１６は開状態のまま、第三スイッチング素子１４及び第一スイッチング素子１５が閉状態に制御される。その結果、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れることになり、第一巻線１２Ｂを流れる一次電流Ｉ１は大きくなっていく。 The discharge control is performed by the ignition control circuit 30 based on the ignition signal IGt output from the engine ECU. In the discharge generation control, the third control signal is transmitted to the third control terminal 14G of the third switching element 14, and the first control signal is transmitted to the first control terminal 15G of the first switching element 15 (time t1). reference). Thereby, the 3rd switching element 14 and the 1st switching element 15 are controlled to a closed state with the 2nd switching element 16 opened. As a result, the primary current I1 flows from the power supply unit 17 to the first winding 12B, and the primary current I1 flowing through the first winding 12B increases.
　そして、第一所定時間の経過後に、第三制御信号が第三スイッチング素子１４の第三制御端子１４Ｇに送信された状態を維持したままの状態で、第一制御信号の出力が停止される（時間ｔ２参照）。これにより、第一スイッチング素子１５が開状態に制御されることになり、第一巻線１２Ｂへ流れる一次電流Ｉ１の電流が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０で火花放電が生じる。 And after progress of 1st predetermined time, the output of a 1st control signal is stopped in the state which has maintained the state with which the 3rd control signal was transmitted to the 3rd control terminal 14G of the 3rd switching element 14 ( Time t2). As a result, the first switching element 15 is controlled to be in an open state, the primary current I1 flowing to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the spark plug 20 Spark discharge occurs.
　そして、点火制御回路３０により放電維持制御が実施される。放電維持制御では、電流検出用経路Ｌ２に流れる二次電流Ｉ２が点火制御回路３０により逐次検出されている。そして、検出された二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、点火プラグ２０で生じた火花放電が消失しないように、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れる制御が行われる。図７の時間ｔ３の時点では、第三スイッチング素子１４が閉状態に制御されており、第二スイッチング素子１６が開状態に制御されている状態であるため、第二制御信号が第二スイッチング素子１６の第二制御端子１６Ｇに送信される。これにより、第二スイッチング素子１６が閉状態に制御され、第二巻線１２Ｃに一次電流Ｉ１が流れ二次電流Ｉ２が増加することになる。 Then, discharge maintenance control is performed by the ignition control circuit 30. In the discharge maintenance control, the secondary current I2 flowing through the current detection path L2 is sequentially detected by the ignition control circuit 30. Then, when the detected absolute value of the secondary current I2 becomes smaller than the first threshold value, the power source unit 17 supplies the second winding 12C so that the spark discharge generated in the spark plug 20 does not disappear. Control in which the primary current I1 flows is performed. At time t3 in FIG. 7, the third switching element 14 is controlled to be in the closed state and the second switching element 16 is controlled to be in the open state. 16 to the second control terminal 16G. As a result, the second switching element 16 is controlled to be closed, and the primary current I1 flows through the second winding 12C, and the secondary current I2 increases.
　検出された二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には、第三制御信号の出力が停止される（時間ｔ４参照）。これにより、第三スイッチング素子１４が開状態に制御されることになり、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１が遮断され、電流還流経路Ｌ１を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなる。以降は、電流検出用経路Ｌ２にて検出される二次電流Ｉ２の絶対値が第一閾値よりも大きく、且つ、第二閾値よりも小さくなるように、第三スイッチング素子１４の開閉動作が制御されることで、放電期間が終了するまで点火プラグ２０で火花放電が継続して生じ続けることになる（時間ｔ３－５参照）。 When the absolute value of the detected secondary current I2 becomes larger than the second threshold value, the output of the third control signal is stopped (see time t4). As a result, the third switching element 14 is controlled to be in the open state, and the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the second winding is passed through the current return path L1. The primary current I1 flows back to 12C. Thereafter, the opening / closing operation of the third switching element 14 is controlled so that the absolute value of the secondary current I2 detected in the current detection path L2 is larger than the first threshold and smaller than the second threshold. Thus, spark discharge continues to occur in the spark plug 20 until the discharge period ends (see time t3-5).
　なお、図７は、燃焼室内の流速が刻々と変化する運転状況下を想定している。放電維持制御を実施している期間中、二次電圧Ｖ２は気流などで放電火花長さが引き延ばされたり短くなったりして安定していない（時間ｔ３－５参照）。しかし、その一方で、二次電流Ｉ２を安定して第一閾値から第二閾値の範囲内に制御することができることから、二次電圧Ｖ２が安定しない運転状態であっても、本点火システム１０は点火プラグ２０で生じている火花放電が吹き消えることを抑えることができるので安定して火花放電を維持させることができる。 Note that FIG. 7 assumes an operating condition in which the flow velocity in the combustion chamber changes every moment. During the period in which the discharge maintenance control is performed, the secondary voltage V2 is not stable because the discharge spark length is extended or shortened by an air current or the like (see time t3-5). However, on the other hand, since the secondary current I2 can be stably controlled within the range from the first threshold value to the second threshold value, the ignition system 10 can be operated even in an operation state where the secondary voltage V2 is not stable. Since the spark discharge generated in the spark plug 20 can be suppressed from being blown out, the spark discharge can be stably maintained.
　本点火システム１０を構築する多くの構成は、点火コイル１１が収容されているケース５０内に収容される。図８を用いてケース５０内の構成を説明する。 Many configurations for constructing the ignition system 10 are accommodated in a case 50 in which the ignition coil 11 is accommodated. The configuration within the case 50 will be described with reference to FIG.
　図８は、特にケース５０周辺の構造を示したものである。ケース５０内には、点火コイル１１が備わっており、内側から外側へ一次コイル１２と、二次コイル１３と、上下に積層した鉄心２３とが装着される。また、鉄心２３とケース５０との間には所定の空間が形成されており、この所定の空間内に、第三スイッチング素子１４と、第一スイッチング素子１５と、第二スイッチング素子１６と、電流還流経路Ｌ１と、電流検出用経路Ｌ２と、点火制御回路３０と、が設けられる。 FIG. 8 shows a structure around the case 50 in particular. An ignition coil 11 is provided in the case 50, and a primary coil 12, a secondary coil 13, and an iron core 23 stacked vertically are mounted from the inside to the outside. A predetermined space is formed between the iron core 23 and the case 50, and the third switching element 14, the first switching element 15, the second switching element 16, and the current are formed in the predetermined space. A reflux path L1, a current detection path L2, and an ignition control circuit 30 are provided.
　二次コイル１３とケース５０との間には防止ダイオード２１が設けられており、防止ダイオード２１のアノード側は二次コイル１３の第一端と配線により電気的に接続されている。また、防止ダイオード２１のカソード側は上記所定の空間内に設けられた電流検出用経路Ｌ２と接続されている。 The prevention diode 21 is provided between the secondary coil 13 and the case 50, and the anode side of the prevention diode 21 is electrically connected to the first end of the secondary coil 13 by wiring. The cathode side of the prevention diode 21 is connected to a current detection path L2 provided in the predetermined space.
　以上の通り、ケース５０内に電源部１７や点火プラグ２０を除く点火システム１０を構築する他の構成を収容することができる。これにより、配線を削減することができ、また本点火システム１０の肥大化を抑えることができるので、車両への搭載性向上を図ることができる。 As described above, other configurations for constructing the ignition system 10 excluding the power supply unit 17 and the spark plug 20 can be accommodated in the case 50. Thereby, since wiring can be reduced and the enlargement of this ignition system 10 can be suppressed, the mounting property to a vehicle can be improved.
　なお、第一実施形態を、以下のように変更して実施することもできる。 Note that the first embodiment can be implemented with the following modifications.
　・第一実施形態に係る放電制御の態様を、図７を参照して説明していた。この図７では、エンジンＥＣＵより出力された点火信号ＩＧｔに基づいて、点火制御回路３０により放電発生制御が実施されてから、点火プラグ２０で火花放電が生じ、二次電流Ｉ２の絶対値が第一閾値よりも小さくなるまでの期間（時間ｔ１－ｔ３参照）、第二スイッチング素子１６は開状態に、第三スイッチング素子１４は閉状態に制御されていた。このことについて、図９に記載されるように、第一スイッチング素子１５が開状態に制御されることで、二次コイル１３に高電圧が誘起して以降、二次電流Ｉ２の絶対値が第一閾値よりも小さくなるまでの間に、第二制御信号を出力した上で、第三制御信号の出力を停止する構成としてもよい（時間ｔ８参照）。かかる構成によっても、上記実施形態に準じた作用・効果が奏される。 The aspect of the discharge control according to the first embodiment has been described with reference to FIG. In FIG. 7, based on the ignition signal IGt output from the engine ECU, after the discharge control is performed by the ignition control circuit 30, spark discharge occurs in the spark plug 20, and the absolute value of the secondary current I2 is the first value. During the period until it becomes smaller than one threshold (see time t1-t3), the second switching element 16 is controlled to be in the open state, and the third switching element 14 is controlled to be in the closed state. With respect to this, as shown in FIG. 9, the first switching element 15 is controlled to be in an open state, so that a high voltage is induced in the secondary coil 13, and thus the absolute value of the secondary current I <b> 2 is the first value. A configuration may be adopted in which the output of the third control signal is stopped after the second control signal is output until it becomes smaller than one threshold (see time t8). Even with such a configuration, the operation and effect according to the above-described embodiment can be achieved.
　・第一実施形態では、放電維持制御を実施している期間中、検出した二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には第三スイッチング素子１４が閉状態に制御され、検出した二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には第三スイッチング素子１４が開状態に制御されていた。このことについて、第三スイッチング素子１４の開閉制御を二次電流Ｉ２の値に関わらず所定の時間で制御してもよい。例えば、放電維持制御を実施している期間中、第二所定時間の経過毎に、第三スイッチング素子１４の開閉状態を切替えてもよい。この場合、放電維持制御を実施している期間中に二次電流Ｉ２を検出する必要がなくなるため、電流検出用経路Ｌ２を形成する必要がなくなり、点火システム１０のコスト削減を図ることが可能となる。 In the first embodiment, the third switching element 14 is controlled to be closed when the absolute value of the detected secondary current I2 becomes smaller than the first threshold during the period in which the discharge maintenance control is performed. When the detected absolute value of the secondary current I2 becomes larger than the second threshold value, the third switching element 14 is controlled to be in the open state. In this regard, the opening / closing control of the third switching element 14 may be controlled in a predetermined time regardless of the value of the secondary current I2. For example, the open / close state of the third switching element 14 may be switched each time the second predetermined time elapses during the period in which the discharge maintenance control is performed. In this case, since it is not necessary to detect the secondary current I2 during the period during which the discharge maintenance control is being performed, it is not necessary to form the current detection path L2, and the cost of the ignition system 10 can be reduced. Become.
　・第一実施形態では、放電維持制御を実施している期間中、第一スイッチング素子１５を常に開状態に制御する。この状態で、二次電流Ｉ２の絶対値が第一閾値よりも小さい場合には、第三スイッチング素子１４及び第二スイッチング素子１６を閉状態に制御し、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には、第二スイッチング素子１６は閉状態のまま第三スイッチング素子１４を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通と還流を行っていた。この放電維持制御に代えて、放電維持制御を実施している期間中は、第一スイッチング素子１５を常に開状態に制御する。この状態で、二次電流Ｉ２の絶対値が第一閾値よりも小さい場合には、第三スイッチング素子１４及び第二スイッチング素子１６を閉状態に制御し、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には、第三スイッチング素子１４は閉状態のまま第二スイッチング素子１６を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通と遮断を行ってもよい。これによっても、第一実施形態と同様の効果を奏することができる。 In the first embodiment, the first switching element 15 is always controlled to be in the open state during the period when the discharge maintenance control is performed. In this state, when the absolute value of the secondary current I2 is smaller than the first threshold, the third switching element 14 and the second switching element 16 are controlled to be closed, and the absolute value of the secondary current I2 is set to the second value. When it becomes larger than the threshold value, the second switching element 16 is controlled to be in the closed state while the second switching element 16 is closed, so that the primary current I1 flowing from the power supply unit 17 to the second winding 12C is increased. Conduction and reflux were performed. Instead of the discharge maintenance control, the first switching element 15 is always controlled to be in the open state during the period in which the discharge maintenance control is performed. In this state, when the absolute value of the secondary current I2 is smaller than the first threshold, the third switching element 14 and the second switching element 16 are controlled to be closed, and the absolute value of the secondary current I2 is set to the second value. When it becomes larger than the threshold value, the third switching element 14 is closed and the second switching element 16 is controlled to be opened, so that the primary current I1 flowing from the power supply unit 17 to the second winding 12C is increased. Conduction and interruption may be performed. This also has the same effect as the first embodiment.
　・第一実施形態では、カソード側が第二スイッチング素子１６に接続されており、アノード側が第二巻線１２Ｃにおける第二スイッチング素子１６側の端部に接続されている第三ダイオード１９が設けられていた。このことについて、図１０に示されるように、第三ダイオード１９は、カソード側が中間タップ１２Ａに接続され、アノード側が第三スイッチング素子１４の第三接地側端子１４Ｓに接続されるように構成されてもよい。これにより、第三ダイオード１９は、誤って電源部１７を逆極性で組み付けたときの電流の逆流を防止することができる。本別例に係る構成では、電流還流経路Ｌ１に備わる第一ダイオード１８のカソード側が中間タップ１２Ａと第三ダイオード１９との間の電流経路に接続されており、第一ダイオード１８のアノード側が接地されていてもよい。 In the first embodiment, the third diode 19 is provided in which the cathode side is connected to the second switching element 16 and the anode side is connected to the end of the second winding 12C on the second switching element 16 side. It was. In this regard, as shown in FIG. 10, the third diode 19 is configured such that the cathode side is connected to the intermediate tap 12 </ b> A and the anode side is connected to the third ground side terminal 14 </ b> S of the third switching element 14. Also good. Thereby, the 3rd diode 19 can prevent the backflow of an electric current when the power supply part 17 is assembled | attached by reverse polarity accidentally. In the configuration according to this example, the cathode side of the first diode 18 provided in the current return path L1 is connected to the current path between the intermediate tap 12A and the third diode 19, and the anode side of the first diode 18 is grounded. It may be.
　・この場合に、図１１に示すように、点火制御回路３０は、図示しないエンジンＥＣＵより出力された点火信号ＩＧｔ及びエネルギ投入信号ＩＧｗを受信するように、エンジンＥＣＵに接続されていてもよい。点火信号ＩＧｔ（放電開始信号）は、放電開始制御（放電発生制御）において、第一巻線１２Ｂへの通電期間を設定する。エネルギ投入信号ＩＧｗ（電流制御信号）は、放電維持制御において、二次電流Ｉ２の指令値及び放電維持制御の終了時期を設定する。また、点火制御回路３０は、第一スイッチング素子１５、第二スイッチング素子１６、及び第三スイッチング素子１４の開閉動作を制御するように、第一制御端子１５Ｇ、第二制御端子１６Ｇ、及び第三制御端子１４Ｇに接続されている。なお、第三ダイオード１９と第三スイッチング素子１４とを逆に配置してもよい。 In this case, as shown in FIG. 11, the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown). The ignition signal IGt (discharge start signal) sets an energization period to the first winding 12B in the discharge start control (discharge generation control). The energy input signal IGw (current control signal) sets the command value of the secondary current I2 and the end time of the discharge maintenance control in the discharge maintenance control. The ignition control circuit 30 also controls the first control terminal 15G, the second control terminal 16G, and the third control terminal so as to control the opening / closing operations of the first switching element 15, the second switching element 16, and the third switching element 14. It is connected to the control terminal 14G. In addition, you may arrange | position the 3rd diode 19 and the 3rd switching element 14 reversely.
　例えば、図１２～１４に示すように、点火信号ＩＧｔ及びエネルギ投入信号ＩＧｗにより、第一巻線１２Ｂへの通電期間、及び放電維持制御における二次電流Ｉ２の指令値を設定する。すなわち、点火信号ＩＧｔがハイの期間に第一巻線１２Ｂへ通電する。また、点火信号ＩＧｔの立ち上がり時期とエネルギ投入信号ＩＧｗとの立ち上がり時期とに時間差を設け、この時間差の長さに基づいて二次電流Ｉ２の指令値を設定する。 For example, as shown in FIGS. 12 to 14, the energization period to the first winding 12B and the command value of the secondary current I2 in the discharge maintenance control are set by the ignition signal IGt and the energy input signal IGw. That is, the first winding 12B is energized while the ignition signal IGt is high. Further, a time difference is provided between the rising timing of the ignition signal IGt and the rising timing of the energy input signal IGw, and the command value of the secondary current I2 is set based on the length of this time difference.
　例えば、時間差が０ｍｓの場合に二次電流Ｉ２の指令値を１００ｍｓに設定し、時間差が１ｍｓの場合に二次電流Ｉ２の指令値を５０ｍｓに設定し、時間差が２ｍｓの場合に二次電流Ｉ２の指令値を２０ｍｓに設定する。そして、二次電流Ｉ２の指令値を上記第一閾値とし、二次電流Ｉ２の指令値に所定値を加えた値を上記第二閾値とすればよい。なお、この時間差と二次電流Ｉ２の指令値との組み合わせは、任意に変更可能である。また、エネルギ投入信号ＩＧｗの立ち下がり時期により、放電維持制御の終了時期を設定する。上記点火信号ＩＧｔに基づく第一巻線１２Ｂへの通電期間の設定、並びにエネルギ投入信号ＩＧｗに基づく二次電流Ｉ２の指令値及び放電維持制御の終了時期の設定は、他の実施形態及びそれらの変更例にも適用することができる。 For example, when the time difference is 0 ms, the command value of the secondary current I2 is set to 100 ms, when the time difference is 1 ms, the command value of the secondary current I2 is set to 50 ms, and when the time difference is 2 ms, the secondary current I2 Is set to 20 ms. Then, the command value of the secondary current I2 may be set as the first threshold value, and a value obtained by adding a predetermined value to the command value of the secondary current I2 may be set as the second threshold value. Note that the combination of the time difference and the command value of the secondary current I2 can be arbitrarily changed. Further, the end timing of the discharge maintenance control is set according to the falling timing of the energy input signal IGw. The setting of the energization period to the first winding 12B based on the ignition signal IGt, and the setting of the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw It can also be applied to modified examples.
　図１５に示すように、放電開始制御を実施している期間中、第二制御信号により、第二スイッチング素子１６を開状態に制御する。その上で、点火信号ＩＧｔが立ち上がることで、第一制御信号及び第三制御信号により第一スイッチング素子１５及び第三スイッチング素子１４を閉状態に制御し、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れる。そして、点火信号ＩＧｔが立ち下がることで、第一制御信号及び第三制御信号により第一スイッチング素子１５及び第三スイッチング素子１４を開状態に制御する。これにより、電源部１７から第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０の火花ギャップ部の気体が絶縁破壊することで、点火プラグ２０で火花放電が生じる。 As shown in FIG. 15, the second switching element 16 is controlled to be in an open state by the second control signal during the period when the discharge start control is performed. Then, when the ignition signal IGt rises, the first switching element 15 and the third switching element 14 are controlled to be closed by the first control signal and the third control signal, and the power supply unit 17 transfers to the first winding 12B. Primary current I1 flows. Then, when the ignition signal IGt falls, the first switching element 15 and the third switching element 14 are controlled to be opened by the first control signal and the third control signal. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
　そして、放電開始制御を実施後、放電維持制御を実施する。放電維持制御を実施している期間中は、第一スイッチング素子１５を第一制御信号により開状態に制御する。この状態で、第二制御信号及び第三制御信号により、第二スイッチング素子１６と第三スイッチング素子１４とを閉状態に制御することで、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れることになる。そして、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合に、第三制御信号により第三スイッチング素子１４を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断する。これにより、電流還流経路Ｌ１を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなり緩やかに第二巻線１２Ｃの電流は減衰していき、二次電流Ｉ２も低下していく。そして、二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、再度、第三制御信号により第三スイッチング素子１４が閉状態に制御される。 Then, after the discharge start control is performed, the discharge maintenance control is performed. During the period when the discharge maintenance control is performed, the first switching element 15 is controlled to be in an open state by the first control signal. In this state, by controlling the second switching element 16 and the third switching element 14 to be closed by the second control signal and the third control signal, the primary current I1 is supplied from the power supply unit 17 to the second winding 12C. Will flow. When the absolute value of the secondary current I2 becomes larger than the second threshold value, the third switching element 14 is controlled to be opened by the third control signal, so that the power supply unit 17 can supply the second winding 12C. The conduction of the primary current I1 flowing through is interrupted. As a result, the primary current I1 returns to the second winding 12C via the current return path L1, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases. When the absolute value of the secondary current I2 becomes smaller than the first threshold, the third switching element 14 is again controlled to be closed by the third control signal.
　・あるいは、図１６に示されるように、電流還流経路Ｌ１に代えて、電流還流経路Ｌ４を備えてもよい。電流還流経路Ｌ４は第二ダイオード４１を備えており、第二ダイオード４１のカソード側は、第二巻線１２Ｃと第二スイッチング素子１６との間の電流経路Ｌ５に接続され、第二ダイオード４１のアノード側は第三ダイオード１９と中間タップ１２Ａとの間の電流経路Ｌ６に接続される。 Alternatively, as shown in FIG. 16, a current return path L4 may be provided instead of the current return path L1. The current return path L4 includes a second diode 41. The cathode side of the second diode 41 is connected to the current path L5 between the second winding 12C and the second switching element 16, and the second diode 41 The anode side is connected to a current path L6 between the third diode 19 and the intermediate tap 12A.
　・この場合に、図１７に示すように、点火制御回路３０は、図示しないエンジンＥＣＵより出力された点火信号ＩＧｔ及びエネルギ投入信号ＩＧｗを受信するように、エンジンＥＣＵに接続されていてもよい。そして、点火制御回路３０は、上記点火信号ＩＧｔに基づいて第一巻線１２Ｂへの通電期間を設定し、エネルギ投入信号ＩＧｗに基づいて二次電流Ｉ２の指令値及び放電維持制御の終了時期を設定する。 In this case, as shown in FIG. 17, the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown). The ignition control circuit 30 sets the energization period for the first winding 12B based on the ignition signal IGt, and determines the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw. Set.
　図１８に示すように、放電開始制御の態様は図１５と同様である。そして、放電開始制御を実施後、放電維持制御を実施する。 As shown in FIG. 18, the mode of discharge start control is the same as in FIG. And discharge maintenance control is implemented after implementing discharge start control.
　放電維持制御を実施している期間中は、第一スイッチング素子１５を第一制御信号により開状態に制御する。この状態で、第二制御信号及び第三制御信号により、第二スイッチング素子１６と第三スイッチング素子１４とを閉状態に制御することで、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れることになる。そして、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合に、第二制御信号により第二スイッチング素子１６を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断する。これにより、電流還流経路Ｌ４を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなり緩やかに第二巻線１２Ｃの電流は減衰していき、二次電流Ｉ２も低下していく。そして、二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、再度、第二制御信号により第二スイッチング素子１６が閉状態に制御される。 During the period when the discharge maintenance control is performed, the first switching element 15 is controlled to be in an open state by the first control signal. In this state, by controlling the second switching element 16 and the third switching element 14 to be closed by the second control signal and the third control signal, the primary current I1 is supplied from the power supply unit 17 to the second winding 12C. Will flow. Then, when the absolute value of the secondary current I2 becomes larger than the second threshold value, the second switching element 16 is controlled to be in an open state by the second control signal, so that the power supply unit 17 transfers to the second winding 12C. The conduction of the primary current I1 flowing through is interrupted. As a result, the primary current I1 returns to the second winding 12C via the current return path L4, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases. When the absolute value of the secondary current I2 becomes smaller than the first threshold value, the second switching element 16 is again controlled to be closed by the second control signal.
　図１６の構成では、第二ダイオード４１を備えた電流還流経路Ｌ４が備わっていた。このことについて、図１９に示すように、電流還流経路Ｌ４において、第二ダイオード４１のアノード側には第四スイッチング素子４３が備わっていてもよい。第四スイッチング素子４３は、半導体スイッチング素子であって、第四制御端子４３Ｇと、第四電源側端子４３Ｄと、第四接地側端子４３Ｓと、を有している。この第四スイッチング素子４３は、第四制御端子４３Ｇに入力された第四制御信号に基づいて、第四電源側端子４３Ｄと第四接地側端子４３Ｓとの間の通電のオンオフを制御するように構成されている。第四スイッチング素子４３は、第四電源側端子４３Ｄは第二ダイオード４１に接続されており、第四接地側端子４３Ｓは電流経路Ｌ５に接続されている。 In the configuration of FIG. 16, a current return path L4 including the second diode 41 is provided. In this regard, as shown in FIG. 19, a fourth switching element 43 may be provided on the anode side of the second diode 41 in the current return path L4. The fourth switching element 43 is a semiconductor switching element, and includes a fourth control terminal 43G, a fourth power supply side terminal 43D, and a fourth ground side terminal 43S. The fourth switching element 43 controls on / off of energization between the fourth power supply side terminal 43D and the fourth ground side terminal 43S based on the fourth control signal input to the fourth control terminal 43G. It is configured. In the fourth switching element 43, the fourth power supply side terminal 43D is connected to the second diode 41, and the fourth ground side terminal 43S is connected to the current path L5.
　図１９の構成における放電開始制御の態様を説明する。 A mode of discharge start control in the configuration of FIG. 19 will be described.
　放電開始制御を実施している期間中、第二スイッチング素子１６と第四スイッチング素子４３を常に開状態に制御する。その上で、第三スイッチング素子１４及び第一スイッチング素子１５を閉状態に制御することで、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れる。そして、第一所定時間の経過後に第一スイッチング素子１５を開状態に制御する。これにより、電源部１７から第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０の火花ギャップ部の気体が絶縁破壊することで、点火プラグ２０で火花放電が生じる。 During the period when the discharge start control is performed, the second switching element 16 and the fourth switching element 43 are always controlled to be in the open state. Then, by controlling the third switching element 14 and the first switching element 15 to be closed, the primary current I1 flows from the power supply unit 17 to the first winding 12B. Then, the first switching element 15 is controlled to be in an open state after the first predetermined time has elapsed. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
　図１９の構成における放電維持制御の態様を説明する。 A mode of discharge maintenance control in the configuration of FIG. 19 will be described.
　放電開始制御を実施後、放電維持制御を実施する。放電維持制御を実施している期間中は、第一スイッチング素子１５を常に開状態に制御する。この状態で、第三スイッチング素子１４と、第二スイッチング素子１６と、第四スイッチング素子４３と、を閉状態に制御することで、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れることになる。そして、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合に、第二スイッチング素子１６を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断する。これにより、電流還流経路Ｌ４を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなり緩やかに第二巻線１２Ｃの電流は減衰していき、二次電流Ｉ２も低下していく。そして、二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、再度、第二スイッチング素子１６が閉状態に制御される。 After the discharge start control is performed, discharge maintenance control is performed. During the period in which the discharge maintenance control is performed, the first switching element 15 is always controlled to be in the open state. In this state, the primary current I1 flows from the power supply unit 17 to the second winding 12C by controlling the third switching element 14, the second switching element 16, and the fourth switching element 43 to be closed. It will be. When the absolute value of the secondary current I2 becomes larger than the second threshold value, the primary current I1 that flows from the power supply unit 17 to the second winding 12C is controlled by controlling the second switching element 16 to the open state. The continuity of is interrupted. As a result, the primary current I1 returns to the second winding 12C via the current return path L4, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases. When the absolute value of the secondary current I2 becomes smaller than the first threshold value, the second switching element 16 is again controlled to be closed.
　図１９のように、電流還流経路Ｌ４に第四スイッチング素子４３を設けることで、放電発生時に第一巻線１２Ｂから第二巻線１２Ｃに鎖交する磁束により発生する電圧で還流電流が流れ、二次電圧Ｖ２が低下することを抑制することができる。 As shown in FIG. 19, by providing the fourth switching element 43 in the current return path L4, a return current flows with a voltage generated by a magnetic flux interlinked from the first winding 12B to the second winding 12C when a discharge occurs. It can suppress that secondary voltage V2 falls.
　＜第二実施形態＞
　以下、第二実施形態について、第一実施形態との相違点を中心に説明する。 <Second embodiment>
Hereinafter, the second embodiment will be described focusing on differences from the first embodiment.
　第一実施形態において、中間タップ１２Ａは、第三スイッチング素子１４を介して電源部１７に接続されていた。このことについて、図２０に記載されるように、第三スイッチング素子１４を削除することで、中間タップ１２Ａが直接電源部１７に接続される構成とする。また、第二実施形態に係る点火システム１０は、電流還流経路Ｌ１に代えて、電流還流経路Ｌ４を備えている。電流還流経路Ｌ４は第二ダイオード４１を備えており、第二ダイオード４１のカソード側は、第二巻線１２Ｃと第三ダイオード１９との間の電流経路Ｌ５に接続され、第二ダイオード４１のアノード側は電源部１７と中間タップ１２Ａとの間の電流経路Ｌ６に接続される。 In the first embodiment, the intermediate tap 12A is connected to the power supply unit 17 via the third switching element 14. In this regard, as shown in FIG. 20, the intermediate tap 12 </ b> A is directly connected to the power supply unit 17 by deleting the third switching element 14. The ignition system 10 according to the second embodiment includes a current return path L4 instead of the current return path L1. The current return path L4 includes a second diode 41. The cathode side of the second diode 41 is connected to a current path L5 between the second winding 12C and the third diode 19, and the anode of the second diode 41 The side is connected to a current path L6 between the power supply unit 17 and the intermediate tap 12A.
　なお、第二実施形態に係る第三ダイオード１９は、第一実施形態同様、カソード側が第二スイッチング素子１６に接続されており、アノード側は第二巻線１２Ｃにおける第二スイッチング素子１６側の端部に接続されている。これにより、放電開始制御時に第二スイッチング素子１６から第二巻線１２Ｃを介して電源部１７へと電流が流れることを抑制する事が可能となり放電開始制御の発生電圧の低下を防止することができる。 As in the first embodiment, the third diode 19 according to the second embodiment is connected to the second switching element 16 on the cathode side, and the anode side is the end of the second winding 12C on the second switching element 16 side. Connected to the department. As a result, it is possible to suppress a current from flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C during the discharge start control, and to prevent a decrease in the voltage generated during the discharge start control. it can.
　上記構成とすることで、第三スイッチング素子１４を設ける必要がなくなる分、放電制御の簡便化を図ることができる。加えて、点火システム１０のコスト削減を図ることができる。以下、図２０及び図２１を参照して、第二実施形態に係る放電制御の態様を説明する。 By adopting the above configuration, discharge control can be simplified because the third switching element 14 need not be provided. In addition, the cost of the ignition system 10 can be reduced. Hereinafter, with reference to FIG. 20 and FIG. 21, the aspect of the discharge control which concerns on 2nd embodiment is demonstrated.
　エンジンＥＣＵより出力された点火信号ＩＧｔに基づいて、点火制御回路３０により放電発生制御が実施される。放電発生制御では、第一制御信号が第一スイッチング素子１５の第一制御端子１５Ｇに送信される（時間ｔ１１参照）。これにより、第二スイッチング素子１６は開状態のまま、第一スイッチング素子１５が閉状態に制御される。その結果、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れることになり、第一巻線１２Ｂを流れる一次電流Ｉ１は大きくなる。 The discharge control is performed by the ignition control circuit 30 based on the ignition signal IGt output from the engine ECU. In the discharge generation control, a first control signal is transmitted to the first control terminal 15G of the first switching element 15 (see time t11). Accordingly, the first switching element 15 is controlled to be closed while the second switching element 16 is kept open. As a result, the primary current I1 flows from the power supply unit 17 to the first winding 12B, and the primary current I1 flowing through the first winding 12B increases.
　そして、第一所定時間の経過後に、第一制御信号の出力が停止される（時間ｔ１２参照）。これにより、第一スイッチング素子１５が開状態に制御されることになり、第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０で火花放電が生じる。 Then, after the first predetermined time has elapsed, the output of the first control signal is stopped (see time t12). As a result, the first switching element 15 is controlled to be in an open state, the conduction of the primary current I1 flowing to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the spark plug 20 Spark discharge occurs.
　そして、点火制御回路３０により放電維持制御が実施される。放電維持制御では、電流検出用経路Ｌ２に流れる二次電流Ｉ２が点火制御回路３０により逐次検出されている。検出された二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、第二制御信号が第二スイッチング素子１６の第二制御端子１６Ｇに送信される（時間ｔ１３参照）。これにより、第二スイッチング素子１６が閉状態に制御され、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れる。 Then, discharge maintenance control is performed by the ignition control circuit 30. In the discharge maintenance control, the secondary current I2 flowing through the current detection path L2 is sequentially detected by the ignition control circuit 30. When the detected absolute value of the secondary current I2 is smaller than the first threshold value, the second control signal is transmitted to the second control terminal 16G of the second switching element 16 (see time t13). Thereby, the 2nd switching element 16 is controlled to a closed state, and the primary current I1 flows from the power supply part 17 to the 2nd coil | winding 12C.
　検出された二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には、第二制御信号の出力が停止される（時間ｔ１４参照）。これにより、第二スイッチング素子１６が開状態に制御されることになり、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１が遮断され、電流還流経路Ｌ４を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなり緩やかに第二巻線１２Ｃの電流は減衰していき、二次電流Ｉ２も低下していく。そして、二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、再度、第二スイッチング素子１６が閉状態に制御される。このように放電維持制御期間中は、電流検出用経路Ｌ２にて検出される二次電流Ｉ２の絶対値が第一閾値よりも大きく、且つ、第二閾値よりも小さくなるように、第二スイッチング素子１６の開閉動作が制御されることで、放電期間が終了するまで点火プラグ２０で火花放電が継続して生じ続けることになる（時間ｔ１３－１５参照）。 When the absolute value of the detected secondary current I2 becomes larger than the second threshold value, the output of the second control signal is stopped (see time t14). As a result, the second switching element 16 is controlled to be in the open state, and the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the second winding is passed through the current return path L4. The primary current I1 flows back to 12C, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases. When the absolute value of the secondary current I2 becomes smaller than the first threshold value, the second switching element 16 is again controlled to be closed. Thus, during the discharge maintenance control period, the second switching is performed so that the absolute value of the secondary current I2 detected in the current detection path L2 is larger than the first threshold and smaller than the second threshold. By controlling the opening / closing operation of the element 16, spark discharge continues to occur in the spark plug 20 until the discharge period ends (see time t13-15).
　このように、第一巻線１２Ｂに流れる一次電流Ｉ１の導通と遮断は、第二スイッチング素子１６を開状態に制御した上で、第一スイッチング素子１５を切替ることにより実施することができる。また、第二巻線１２Ｃに流れる一次電流Ｉ１の導通と還流は、第一スイッチング素子１５を開状態に制御した上で、第二スイッチング素子１６を切替ることにより実施することができる。 Thus, the conduction and interruption of the primary current I1 flowing through the first winding 12B can be performed by switching the first switching element 15 after controlling the second switching element 16 to the open state. Further, conduction and recirculation of the primary current I1 flowing through the second winding 12C can be performed by switching the second switching element 16 while controlling the first switching element 15 to be in an open state.
　また、電流還流経路Ｌ４を設けることで、放電維持制御期間中に電流還流経路Ｌ４を流れる一次電流Ｉ１は第一巻線１２Ｂに流れず、第二巻線１２Ｃに流れることとなるため、第一巻線１２Ｂの影響を受けることなく一次電流Ｉ１を精度高く制御することが可能となる。ひいては、二次電流Ｉ２の制御性を高めることができ、その結果として、失火しにくい点火装置を提供することができる。 Also, by providing the current return path L4, the primary current I1 flowing through the current return path L4 during the discharge sustaining control period does not flow to the first winding 12B but flows to the second winding 12C. The primary current I1 can be accurately controlled without being affected by the winding 12B. As a result, the controllability of the secondary current I2 can be improved, and as a result, an ignition device that is unlikely to misfire can be provided.
　ところで、点火システム１０を構築する多くの構成は、点火コイル１１が収容されているケース５０内に収容される。第二実施形態においても、鉄心２３とケース５０との間には所定の空間が形成されており、この所定の空間内に、第一スイッチング素子１５と、第二スイッチング素子１６と、電流還流経路Ｌ７と、電流検出用経路Ｌ２と、点火制御回路３０と、が設けられる。 By the way, many configurations for constructing the ignition system 10 are accommodated in a case 50 in which the ignition coil 11 is accommodated. Also in the second embodiment, a predetermined space is formed between the iron core 23 and the case 50, and the first switching element 15, the second switching element 16, and the current return path are formed in the predetermined space. L7, a current detection path L2, and an ignition control circuit 30 are provided.
　つまり、点火プラグ２０のうち点火コイル１１が収納されている空間内に本内燃機関用点火システムを収容することができる。これにより、配線を削減することができ、また本内燃機関用点火システムの肥大化を抑えることができるので、車両への搭載性向上を図ることができる。 That is, the ignition system for the internal combustion engine can be accommodated in the space where the ignition coil 11 is accommodated in the ignition plug 20. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
　なお、第二実施形態を、以下のように変更して実施することもできる。 It should be noted that the second embodiment can be implemented with the following modifications.
　・第二実施形態に適用される別例として、図２２に示されるように、第三ダイオード１９は、カソード側が中間タップ１２Ａに接続され、アノード側が電源部１７に接続されるように構成されてもよい。これにより、誤って電源部１７を逆極性で組み付けたときの逆流を防止することができる。 As another example applied to the second embodiment, as shown in FIG. 22, the third diode 19 is configured such that the cathode side is connected to the intermediate tap 12 </ b> A and the anode side is connected to the power supply unit 17. Also good. Thereby, backflow when the power supply part 17 is assembled | attached by reverse polarity accidentally can be prevented.
　・第二実施形態では、放電維持制御を実施している期間中、検出した二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には第二スイッチング素子１６が閉状態に制御され、検出した二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には第二スイッチング素子１６が開状態に制御されていた。このことについて、第二スイッチング素子１６の開閉制御を二次電流Ｉ２の値に関わらず所定の時間で制御してもよい。例えば、放電維持制御を実施している期間中、第二所定時間の経過毎に、第二スイッチング素子１６の開閉状態を切替えてもよい。この場合、放電維持制御を実施している期間中に二次電流Ｉ２を検出する必要がなくなるため、電流検出用経路Ｌ２を形成する必要がなくなり、点火システム１０の小型化やコスト削減を図ることが可能となる。 In the second embodiment, the second switching element 16 is controlled to be closed when the absolute value of the detected secondary current I2 becomes smaller than the first threshold during the period when the discharge maintenance control is being performed. When the detected absolute value of the secondary current I2 is larger than the second threshold value, the second switching element 16 is controlled to be in the open state. With respect to this, the opening / closing control of the second switching element 16 may be controlled in a predetermined time regardless of the value of the secondary current I2. For example, the open / close state of the second switching element 16 may be switched every time the second predetermined time elapses during the period in which the discharge maintenance control is performed. In this case, since it is not necessary to detect the secondary current I2 during the period during which the discharge maintenance control is performed, it is not necessary to form the current detection path L2, and the ignition system 10 can be reduced in size and cost. Is possible.
　・第二実施形態では、電流還流経路Ｌ４に第二ダイオード４１を設けていた。このことについて、図１９に示す電流還流経路Ｌ４と同様の構成を適用してもよい。具体的には、図２３に示すように、第二実施形態においても、電流還流経路Ｌ４における第二ダイオード４１のアノード側に第四スイッチング素子４３が備わっていてもよい。この場合、図１９に示す別例に準じた作用及び効果を奏することができる。 In the second embodiment, the second diode 41 is provided in the current return path L4. About this, you may apply the structure similar to the electric current return path | route L4 shown in FIG. Specifically, as shown in FIG. 23, also in the second embodiment, a fourth switching element 43 may be provided on the anode side of the second diode 41 in the current return path L4. In this case, operations and effects according to another example shown in FIG. 19 can be achieved.
　・この場合に、図２３に示すように、点火制御回路３０は、図示しないエンジンＥＣＵより出力された点火信号ＩＧｔ及びエネルギ投入信号ＩＧｗを受信するように、エンジンＥＣＵに接続されていてもよい。そして、点火制御回路３０は、上記点火信号ＩＧｔに基づいて第一巻線１２Ｂへの通電期間を設定し、エネルギ投入信号ＩＧｗに基づいて二次電流Ｉ２の指令値及び放電維持制御の終了時期を設定する。また、点火制御回路３０は、第一スイッチング素子１５、第二スイッチング素子１６、及び第四スイッチング素子４３の開閉動作を制御するように、第一制御端子１５Ｇ、第二制御端子１６Ｇ、及び第四制御端子４３Ｇに接続されている。なお、第二ダイオード４１と第四スイッチング素子４３とを逆に配置してもよい。 In this case, as shown in FIG. 23, the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown). The ignition control circuit 30 sets the energization period for the first winding 12B based on the ignition signal IGt, and determines the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw. Set. In addition, the ignition control circuit 30 controls the opening / closing operation of the first switching element 15, the second switching element 16, and the fourth switching element 43 so that the first control terminal 15G, the second control terminal 16G, and the fourth It is connected to the control terminal 43G. The second diode 41 and the fourth switching element 43 may be arranged in reverse.
　図２４に示すように、放電開始制御を実施している期間中、第二制御信号及び第四制御信号により、第二スイッチング素子１６と第四スイッチング素子４３を開状態に制御する。その上で、点火信号ＩＧｔが立ち上がることで、第一制御信号により第一スイッチング素子１５を閉状態に制御し、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れる。そして、点火信号ＩＧｔが立ち下がることで、第一制御信号により第一スイッチング素子１５を開状態に制御する。これにより、電源部１７から第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０の火花ギャップ部の気体が絶縁破壊することで、点火プラグ２０で火花放電が生じる。 As shown in FIG. 24, the second switching element 16 and the fourth switching element 43 are controlled to be in an open state by the second control signal and the fourth control signal during the period in which the discharge start control is performed. After that, the ignition signal IGt rises, whereby the first switching element 15 is controlled to be closed by the first control signal, and the primary current I1 flows from the power supply unit 17 to the first winding 12B. Then, when the ignition signal IGt falls, the first switching element 15 is controlled to be in the open state by the first control signal. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
　そして、放電開始制御を実施後、放電維持制御を実施する。放電維持制御を実施している期間中は、第一制御信号により、第一スイッチング素子１５を開状態に制御する。この状態で、第二制御信号及び第四制御信号により、第二スイッチング素子１６と第四スイッチング素子４３とを閉状態に制御することで、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れることになる。そして、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合に、第二制御信号により第二スイッチング素子１６を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断する。これにより、電流還流経路Ｌ４を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなり緩やかに第二巻線１２Ｃの電流は減衰していき、二次電流Ｉ２も低下していく。そして、二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、再度、第二制御信号により第二スイッチング素子１６が閉状態に制御される。 Then, after the discharge start control is performed, the discharge maintenance control is performed. During the period when the discharge maintenance control is performed, the first switching element 15 is controlled to be in the open state by the first control signal. In this state, by controlling the second switching element 16 and the fourth switching element 43 in the closed state by the second control signal and the fourth control signal, the primary current I1 from the power supply unit 17 to the second winding 12C. Will flow. Then, when the absolute value of the secondary current I2 becomes larger than the second threshold value, the second switching element 16 is controlled to be in an open state by the second control signal, so that the power supply unit 17 transfers to the second winding 12C. The conduction of the primary current I1 flowing through is interrupted. As a result, the primary current I1 returns to the second winding 12C via the current return path L4, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases. When the absolute value of the secondary current I2 becomes smaller than the first threshold value, the second switching element 16 is again controlled to be closed by the second control signal.
　・第三ダイオード１９の位置を、図２３に示す位置から図２５に示す位置に変更することもできる。すなわち、第三ダイオード１９は、第一実施形態同様、カソード側が第二スイッチング素子１６に接続されており、アノード側が第二巻線１２Ｃにおける第二スイッチング素子１６側の端部に接続されている。なお、第三ダイオード１９と第二スイッチング素子１６とを逆に配置してもよい。 The position of the third diode 19 can be changed from the position shown in FIG. 23 to the position shown in FIG. That is, as in the first embodiment, the third diode 19 has a cathode side connected to the second switching element 16 and an anode side connected to the end of the second winding 12C on the second switching element 16 side. In addition, you may arrange | position the 3rd diode 19 and the 2nd switching element 16 reversely.
　＜第三実施形態＞
　以下、第三実施形態について、上述の第二実施形態との相違点を中心に説明する。 <Third embodiment>
Hereinafter, the third embodiment will be described focusing on differences from the above-described second embodiment.
　第二実施形態において、第二スイッチング素子１６の第二電源側端子１６Ｄは第三ダイオード１９を介して第二巻線１２Ｃに接続されており、第二接地側端子１６Ｓは接地されていた。この点、図２６に記載されるように、第二スイッチング素子１６を削除し、第三スイッチング素子１４を追加する。この第三スイッチング素子１４は、第三電源側端子１４Ｄが中間タップ１２Ａに接続されており、第三スイッチング素子１４の第三接地側端子１４Ｓが第二巻線１２Ｃに接続されている。そして、電流還流経路Ｌ７に備わる第四ダイオード４２のカソード側は、第三スイッチング素子１４と第二巻線１２Ｃとの間の電流経路Ｌ８に接続され、第四ダイオード４２のアノード側は接地される。これにより、放電維持制御期間中、電流還流経路Ｌ７を流れる一次電流Ｉ１は第一巻線１２Ｂに流れず、直接第二巻線１２Ｃに流れることとなるため、第一巻線１２Ｂの影響を受けることなく一次電流Ｉ１を精度高く制御することが可能となる。 In the second embodiment, the second power supply side terminal 16D of the second switching element 16 is connected to the second winding 12C via the third diode 19, and the second ground side terminal 16S is grounded. In this regard, as described in FIG. 26, the second switching element 16 is deleted and the third switching element 14 is added. In the third switching element 14, the third power supply side terminal 14D is connected to the intermediate tap 12A, and the third ground side terminal 14S of the third switching element 14 is connected to the second winding 12C. The cathode side of the fourth diode 42 provided in the current return path L7 is connected to the current path L8 between the third switching element 14 and the second winding 12C, and the anode side of the fourth diode 42 is grounded. . As a result, during the discharge maintenance control period, the primary current I1 flowing through the current return path L7 does not flow to the first winding 12B but directly flows to the second winding 12C, and thus is affected by the first winding 12B. The primary current I1 can be controlled with high accuracy without any problem.
　第三ダイオード１９は、カソード側が接地側に接続されており、アノード側が第二巻線１２Ｃにおける中間タップ１２Ａ側とは反対側の端部に接続されている。これにより、放電開始制御時に第二スイッチング素子１６から第二巻線１２Ｃを介して電源部１７へと電流が流れることを抑制する事が可能となり放電開始制御の発生電圧の低下を防止することができる。 The third diode 19 has a cathode side connected to the ground side, and an anode side connected to the end of the second winding 12C opposite to the intermediate tap 12A side. As a result, it is possible to suppress a current from flowing from the second switching element 16 to the power supply unit 17 via the second winding 12C during the discharge start control, and to prevent a decrease in the voltage generated during the discharge start control. it can.
　図２６および図２７を参照して、本実施形態に係る放電制御の態様を説明する。 With reference to FIG. 26 and FIG. 27, the aspect of the discharge control which concerns on this embodiment is demonstrated.
　エンジンＥＣＵより出力された点火信号ＩＧｔに基づいて、点火制御回路３０により放電発生制御が実施される。放電発生制御では、第一制御信号が第一スイッチング素子１５の第一制御端子１５Ｇに送信される（時間ｔ２１参照）。これにより、第三スイッチング素子１４は開状態のまま、第一スイッチング素子１５が閉状態に制御される。その結果、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れることになり、第一巻線１２Ｂを流れる一次電流Ｉ１は大きくなる。 The discharge control is performed by the ignition control circuit 30 based on the ignition signal IGt output from the engine ECU. In the discharge generation control, a first control signal is transmitted to the first control terminal 15G of the first switching element 15 (see time t21). As a result, the first switching element 15 is controlled to be closed while the third switching element 14 is kept open. As a result, the primary current I1 flows from the power supply unit 17 to the first winding 12B, and the primary current I1 flowing through the first winding 12B increases.
　そして、第一所定時間の経過後に、第一制御信号の出力が停止される（時間ｔ２２参照）。これにより、第一スイッチング素子１５が開状態に制御されることになり、第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０で火花放電が生じる。 Then, after the first predetermined time has elapsed, the output of the first control signal is stopped (see time t22). As a result, the first switching element 15 is controlled to be in an open state, the conduction of the primary current I1 flowing to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the spark plug 20 Spark discharge occurs.
　そして、点火制御回路３０により放電維持制御が実施される。放電維持制御では、電流検出用経路Ｌ２に流れる二次電流Ｉ２が点火制御回路３０により逐次検出されている。検出された二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、第三制御信号が第三スイッチング素子１４の第三制御端子１４Ｇに送信される（時間ｔ２３参照）。これにより、第三スイッチング素子１４が閉状態に制御され、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れる。 Then, discharge maintenance control is performed by the ignition control circuit 30. In the discharge maintenance control, the secondary current I2 flowing through the current detection path L2 is sequentially detected by the ignition control circuit 30. When the detected absolute value of the secondary current I2 becomes smaller than the first threshold value, the third control signal is transmitted to the third control terminal 14G of the third switching element 14 (see time t23). Thereby, the 3rd switching element 14 is controlled to a closed state, and the primary current I1 flows from the power supply part 17 to the 2nd coil | winding 12C.
　検出された二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には、第三制御信号の出力が停止される（時間ｔ２４参照）。これにより、第三スイッチング素子１４が開状態に制御されることになり、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１が遮断され、電流還流経路Ｌ７を経由して第二巻線１２Ｃに一次電流Ｉ１が還流して減衰することとなる。以降は、電流検出用経路Ｌ２にて検出される二次電流Ｉ２の絶対値が第一閾値よりも大きく、且つ、第二閾値よりも小さくなるように、第三スイッチング素子１４の開閉動作が制御されることで、放電期間が終了するまで点火プラグ２０で火花放電が継続して生じ続けることになる（時間ｔ２３－２５参照）。 When the absolute value of the detected secondary current I2 becomes larger than the second threshold value, the output of the third control signal is stopped (see time t24). As a result, the third switching element 14 is controlled to be in the open state, and the primary current I1 flowing from the power supply unit 17 to the second winding 12C is cut off, and the second winding is passed through the current return path L7. The primary current I1 recirculates to 12C and attenuates. Thereafter, the opening / closing operation of the third switching element 14 is controlled so that the absolute value of the secondary current I2 detected in the current detection path L2 is larger than the first threshold and smaller than the second threshold. As a result, spark discharge continues to occur in the spark plug 20 until the discharge period ends (see time t23-25).
　このように、第一巻線１２Ｂに流れる一次電流Ｉ１の導通と遮断は、第三スイッチング素子１４を開状態に制御した上で、第一スイッチング素子１５を切替ることにより実施することができる。また、第二巻線１２Ｃに流れる一次電流Ｉ１の導通と還流は、第一スイッチング素子１５を開状態に制御した上で、第三スイッチング素子１４を切替ることにより実施することができる。また、上記構成では、電源部１７から中間タップ１２Ａまでの通電経路から第三スイッチング素子１４が除かれている。このため、電源部１７から第一巻線１２Ｂへ一次電流Ｉ１が流れる際に第三スイッチング素子１４を介すことで生じる損失をなくすことができ、放電発生制御の効率を高めることができる。 Thus, the conduction and interruption of the primary current I1 flowing through the first winding 12B can be performed by switching the first switching element 15 while controlling the third switching element 14 to be in an open state. The conduction and recirculation of the primary current I1 flowing through the second winding 12C can be performed by switching the third switching element 14 after controlling the first switching element 15 to the open state. Moreover, in the said structure, the 3rd switching element 14 is remove | excluded from the electricity supply path | route from the power supply part 17 to 12 A of intermediate taps. For this reason, when the primary current I1 flows from the power supply part 17 to the 1st coil | winding 12B, the loss which arises through the 3rd switching element 14 can be eliminated, and the efficiency of discharge generation control can be improved.
　ところで、点火システム１０を構築する多くの構成は、点火コイル１１が収容されているケース５０内に収容される。第三実施形態においても、鉄心２３とケース５０との間には所定の空間が形成されており、この所定の空間内に、第一スイッチング素子１５と、第三スイッチング素子１４と、電流還流経路Ｌ７と、電流検出用経路Ｌ２と、点火制御回路３０と、が設けられる。 By the way, many configurations for constructing the ignition system 10 are accommodated in a case 50 in which the ignition coil 11 is accommodated. Also in the third embodiment, a predetermined space is formed between the iron core 23 and the case 50, and the first switching element 15, the third switching element 14, and the current return path are formed in the predetermined space. L7, a current detection path L2, and an ignition control circuit 30 are provided.
　つまり、点火プラグ２０のうち点火コイル１１が収納されている空間内に本内燃機関用点火システムを収容することができる。これにより、配線を削減することができ、また本内燃機関用点火システムの肥大化を抑えることができるので、車両への搭載性向上を図ることができる。 That is, the ignition system for the internal combustion engine can be accommodated in the space where the ignition coil 11 is accommodated in the ignition plug 20. As a result, the wiring can be reduced and the increase in the ignition system for the internal combustion engine can be suppressed, so that the mountability to the vehicle can be improved.
　第三実施形態を、以下のように変更して実施することもできる。 The third embodiment can be implemented with the following modifications.
　・第三実施形態において、第三ダイオード１９は、カソード側が接地側に接続されており、アノード側が第二巻線１２Ｃにおける中間タップ１２Ａ側とは反対側の端部に接続されていた。このことについて、図２８に示されるように、第三ダイオード１９は、カソード側が第二巻線１２Ｃにおける中間タップ１２Ａ側の端部に接続されており、アノード側が第三スイッチング素子１４に接続される構成であってもよい。 In the third embodiment, the third diode 19 has the cathode side connected to the ground side and the anode side connected to the end of the second winding 12C opposite to the intermediate tap 12A side. In this regard, as shown in FIG. 28, the third diode 19 has the cathode side connected to the end of the second winding 12 </ b> C on the intermediate tap 12 </ b> A side and the anode side connected to the third switching element 14. It may be a configuration.
　・この場合に、図２９に示すように、点火制御回路３０は、図示しないエンジンＥＣＵより出力された点火信号ＩＧｔ及びエネルギ投入信号ＩＧｗを受信するように、エンジンＥＣＵに接続されていてもよい。そして、点火制御回路３０は、上記点火信号ＩＧｔに基づいて第一巻線１２Ｂへの通電期間を設定し、エネルギ投入信号ＩＧｗに基づいて二次電流Ｉ２の指令値及び放電維持制御の終了時期を設定する。また、点火制御回路３０は、第三スイッチング素子１４の開閉動作を制御するように、第三制御端子１４Ｇに接続されている。なお、第三ダイオード１９と第三スイッチング素子１４とを逆に配置してもよい。 In this case, as shown in FIG. 29, the ignition control circuit 30 may be connected to the engine ECU so as to receive an ignition signal IGt and an energy input signal IGw output from an engine ECU (not shown). The ignition control circuit 30 sets the energization period for the first winding 12B based on the ignition signal IGt, and determines the command value of the secondary current I2 and the end timing of the discharge maintenance control based on the energy input signal IGw. Set. The ignition control circuit 30 is connected to the third control terminal 14G so as to control the opening / closing operation of the third switching element 14. In addition, you may arrange | position the 3rd diode 19 and the 3rd switching element 14 reversely.
　図３０に示すように、放電開始制御を実施している期間中、第三制御信号により、第三スイッチング素子１４を開状態に制御する。その上で、点火信号ＩＧｔが立ち上がることで、第一制御信号により第一スイッチング素子１５を閉状態に制御し、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１が流れる。そして、点火信号ＩＧｔが立ち下がることで、第一制御信号により第一スイッチング素子１５を開状態に制御する。これにより、電源部１７から第一巻線１２Ｂへ流れる一次電流Ｉ１の導通が遮断され、二次コイル１３に高電圧が誘起し、点火プラグ２０の火花ギャップ部の気体が絶縁破壊することで、点火プラグ２０で火花放電が生じる。 As shown in FIG. 30, the third switching element 14 is controlled to be in an open state by the third control signal during the period when the discharge start control is being performed. After that, the ignition signal IGt rises, whereby the first switching element 15 is controlled to be closed by the first control signal, and the primary current I1 flows from the power supply unit 17 to the first winding 12B. Then, when the ignition signal IGt falls, the first switching element 15 is controlled to be in the open state by the first control signal. Thereby, the conduction of the primary current I1 flowing from the power supply unit 17 to the first winding 12B is interrupted, a high voltage is induced in the secondary coil 13, and the gas in the spark gap portion of the spark plug 20 breaks down. Spark discharge occurs in the spark plug 20.
　そして、放電開始制御を実施後、放電維持制御を実施する。放電維持制御を実施している期間中は、第一制御信号により、第一スイッチング素子１５を開状態に制御する。この状態で、第三制御信号により、第三スイッチング素子１４を閉状態に制御することで、電源部１７から第二巻線１２Ｃへと一次電流Ｉ１が流れることになる。そして、二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合に、第三制御信号により第三スイッチング素子１４を開状態に制御することで、電源部１７から第二巻線１２Ｃへと流れる一次電流Ｉ１の導通を遮断する。これにより、電流還流経路Ｌ７を経由して第二巻線１２Ｃに一次電流Ｉ１が還流することとなり緩やかに第二巻線１２Ｃの電流は減衰していき、二次電流Ｉ２も低下していく。そして、二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には、再度、第三制御信号により第三スイッチング素子１４が閉状態に制御される。 Then, after the discharge start control is performed, the discharge maintenance control is performed. During the period when the discharge maintenance control is performed, the first switching element 15 is controlled to be in the open state by the first control signal. In this state, the primary current I1 flows from the power supply unit 17 to the second winding 12C by controlling the third switching element 14 to be closed by the third control signal. When the absolute value of the secondary current I2 becomes larger than the second threshold value, the third switching element 14 is controlled to be opened by the third control signal, so that the power supply unit 17 can supply the second winding 12C. The conduction of the primary current I1 flowing through is interrupted. As a result, the primary current I1 returns to the second winding 12C via the current return path L7, and the current of the second winding 12C gradually attenuates, and the secondary current I2 also decreases. When the absolute value of the secondary current I2 becomes smaller than the first threshold, the third switching element 14 is again controlled to be closed by the third control signal.
　・第三実施形態では、放電維持制御を実施している期間中、検出した二次電流Ｉ２の絶対値が第一閾値よりも小さくなった場合には第三スイッチング素子１４が閉状態に制御され、検出した二次電流Ｉ２の絶対値が第二閾値よりも大きくなった場合には第三スイッチング素子１４が開状態に制御されていた。このことについて、第三スイッチング素子１４の開閉制御を二次電流Ｉ２の値に関わらず所定の時間で制御してもよい。例えば、放電維持制御を実施している期間中、第二所定時間の経過毎に、第三スイッチング素子１４の開閉状態を切替えてもよい。この場合、放電維持制御を実施している期間中に二次電流Ｉ２を検出する必要がなくなるため、電流検出用経路Ｌ２を形成する必要がなくなり、点火システム１０の小型化やコスト削減を図ることが可能となる。 In the third embodiment, the third switching element 14 is controlled to be closed when the absolute value of the detected secondary current I2 becomes smaller than the first threshold during the period when the discharge maintenance control is being performed. When the detected absolute value of the secondary current I2 becomes larger than the second threshold value, the third switching element 14 is controlled to be in the open state. In this regard, the opening / closing control of the third switching element 14 may be controlled in a predetermined time regardless of the value of the secondary current I2. For example, the open / close state of the third switching element 14 may be switched each time the second predetermined time elapses during the period in which the discharge maintenance control is performed. In this case, since it is not necessary to detect the secondary current I2 during the period during which the discharge maintenance control is performed, it is not necessary to form the current detection path L2, and the ignition system 10 can be reduced in size and cost. Is possible.
　・第三実施形態に係る放電発生制御では、第三スイッチング素子１４は開状態のまま、第一スイッチング素子１５が閉状態に制御され、第一所定時間の経過後に、第一スイッチング素子１５が開状態に制御される制御が実施されていた。 In the discharge generation control according to the third embodiment, the first switching element 15 is controlled to be closed while the third switching element 14 is open, and the first switching element 15 is opened after the first predetermined time has elapsed. Control to be controlled by the state was implemented.
　この点、放電発生制御時において、第一スイッチング素子１５が閉状態に制御することで、電源部１７から第一巻線１２Ｂへと一次電流Ｉ１を流す一方で、第三スイッチング素子１４を閉状態に制御する構成としてもよい。これにより、第二巻線１２Ｃにも一次電流Ｉ１が流れることになり、その結果、第一巻線１２Ｂと第二巻線１２Ｃとにそれぞれ、互いの磁束を打ち消し合う方向の磁束が発生することになる。これにより、図３１に記載されるように、放電発生制御を実施することで生じる二次電圧Ｖ２は、従来の放電発生制御を実施することで生じる所謂オン電圧も低く抑えることができる。ひいては、防止ダイオード２１に印加される電圧を低くすることができ、防止ダイオード２１の低耐圧化、もしくは防止ダイオード２１を削除した構成とすることができ、点火システム１０のコスト削減を図ることができる。 In this regard, during the discharge generation control, the first switching element 15 is controlled to be closed, so that the primary current I1 flows from the power supply unit 17 to the first winding 12B while the third switching element 14 is closed. It is good also as a structure controlled to. As a result, the primary current I1 also flows through the second winding 12C, and as a result, the first winding 12B and the second winding 12C generate magnetic fluxes in directions that cancel each other's magnetic flux. become. As a result, as shown in FIG. 31, the secondary voltage V <b> 2 generated by performing the discharge generation control can also suppress the so-called on-voltage generated by performing the conventional discharge generation control. As a result, the voltage applied to the prevention diode 21 can be lowered, the prevention diode 21 can be reduced in voltage, or the prevention diode 21 can be omitted, and the cost of the ignition system 10 can be reduced. .
　なお、上記各実施形態を、以下のように変更して実施することもできる。 It should be noted that each of the above embodiments can be modified as follows.
　・上記各実施形態では、点火コイル１１に対して点火信号ＩＧｔを伝達する信号線及びエネルギ投入信号ＩＧｗを伝達する信号線は、図示しないエンジンＥＣＵから、それぞれ独立して接続されていた。これに対して、図３２に示すように、エネルギ投入信号ＩＧｗを伝達する共通の信号線５１を、エンジンＥＣＵ６１（制御装置）に接続してもよい。そして、信号線５１から分岐した信号線５１ａ～５１ｄを、各気筒の点火制御回路３０に接続してもよい。すなわち、エネルギ投入信号ＩＧｗは、全ての気筒＃１～＃４において共通であってもよい。なお、点火信号ＩＧｔは、各気筒に応じた個別の信号になっている。 In each of the above embodiments, the signal line for transmitting the ignition signal IGt and the signal line for transmitting the energy input signal IGw to the ignition coil 11 are connected independently from an engine ECU (not shown). On the other hand, as shown in FIG. 32, a common signal line 51 for transmitting the energy input signal IGw may be connected to the engine ECU 61 (control device). The signal lines 51a to 51d branched from the signal line 51 may be connected to the ignition control circuit 30 of each cylinder. That is, the energy input signal IGw may be common to all the cylinders # 1 to # 4. The ignition signal IGt is an individual signal corresponding to each cylinder.
　・図１２～１５，１８、２４，３０に示すように、例えばエネルギ投入信号ＩＧｗのハイ期間は、点火信号ＩＧｔがハイである期間から放電維持制御が終了する時期まで継続する。このため、エンジン６０が多気筒エンジン（例えばＶ型6気筒エンジン）である場合、図３３に示すように、エネルギ投入信号ＩＧｗを共通にすると、エネルギ投入信号ＩＧｗが常にハイになるおそれがある。すなわち、点火プラグ２０による点火が連続する気筒において、エネルギ投入信号ＩＧｗのハイ期間同士が重複するおそれがある。 As shown in FIGS. 12 to 15, 18, 24, 30, for example, the high period of the energy input signal IGw continues from the period in which the ignition signal IGt is high to the time when the discharge maintenance control ends. For this reason, when the engine 60 is a multi-cylinder engine (for example, a V-type 6-cylinder engine), as shown in FIG. 33, if the energy input signal IGw is shared, the energy input signal IGw may always be high. That is, in the cylinder in which ignition by the spark plug 20 continues, the high periods of the energy input signal IGw may overlap.
　そこで、図３４に示すように、エネルギ投入信号ＩＧｗ１を伝達する共通の信号線５２と、エネルギ投入信号ＩＧｗ２を伝達する共通の信号線５３とを、エンジンＥＣＵ６１に接続してもよい。すなわち、エネルギ投入信号ＩＧｗ１は、一部の気筒＃１，＃３，＃５（一方のバンク）において共通であってもよい。エネルギ投入信号ＩＧｗ２は、一部の気筒＃２，＃４，＃６（他方のバンク）において共通であってもよい。なお、点火信号ＩＧｔは、各気筒に応じた個別の信号になっている。 Therefore, as shown in FIG. 34, a common signal line 52 for transmitting the energy input signal IGw1 and a common signal line 53 for transmitting the energy input signal IGw2 may be connected to the engine ECU 61. That is, the energy input signal IGw1 may be common to some cylinders # 1, # 3, and # 5 (one bank). The energy input signal IGw2 may be common to some cylinders # 2, # 4, and # 6 (the other bank). The ignition signal IGt is an individual signal corresponding to each cylinder.
　そして、信号線５２（第一共通信号線）から分岐した信号線５２ａ～５２ｃを、第1気筒＃１，第３気筒＃３，第５気筒＃５の点火制御回路３０にそれぞれ接続してもよい。第1気筒＃１，第３気筒＃３，第５気筒＃５（第一気筒群）は、点火プラグ２０による点火が連続しない気筒の集まりである。また、信号線５３（第二共通信号線）から分岐した信号線５３ａ～５３ｃを、第２気筒＃２，第４気筒＃４，第６気筒＃６の点火制御回路３０にそれぞれ接続してもよい。第２気筒＃２，第４気筒＃４，第６気筒＃６（第二気筒群）は、点火プラグ２０による点火が連続しない気筒の集まりであり、且つ第一気筒群に含まれない気筒の集まりである。すなわち、第一気筒群に含まれる２つの気筒（例えば第1気筒＃１，第３気筒＃３）で相前後して点火が行われる間に、第二気筒群に含まれる１つの気筒（例えば第２気筒＃２）で点火が行われる。 The signal lines 52a to 52c branched from the signal line 52 (first common signal line) may be connected to the ignition control circuit 30 of the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5, respectively. Good. The first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5 (first cylinder group) are a group of cylinders in which ignition by the spark plug 20 does not continue. Further, the signal lines 53a to 53c branched from the signal line 53 (second common signal line) may be connected to the ignition control circuit 30 of the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6, respectively. Good. The second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6 (second cylinder group) are a group of cylinders that are not continuously ignited by the spark plug 20, and are cylinders not included in the first cylinder group. It is a gathering. In other words, one cylinder (for example, the second cylinder group) (for example, one cylinder (for example, the first cylinder # 1, the third cylinder # 3)) is ignited in succession by the two cylinders (for example, the first cylinder # 1, the third cylinder # 3). Ignition is performed in the second cylinder # 2).
　こうした構成によれば、図３５に示すように、エネルギ投入信号ＩＧｗ１，ＩＧｗ２が常にハイになることを避けることができる。すなわち、第一気筒群の第1気筒＃１，第３気筒＃３，第５気筒＃５の点火は連続しておらず、第一気筒群の第1気筒＃１，第３気筒＃３，第５気筒＃５に伝達されるエネルギ投入信号ＩＧｗ１のハイ期間同士が重複することを抑制することができる。また、第二気筒群の第２気筒＃２，第４気筒＃４，第６気筒＃６の点火は連続しておらず、第二気筒群の第２気筒＃２，第４気筒＃４，第６気筒＃６に伝達されるエネルギ投入信号ＩＧｗ２のハイ期間同士が重複することを抑制することができる。したがって、エンジン６０が多気筒エンジンであっても、エネルギ投入信号ＩＧｗ１，ＩＧｗ２に基づいて、二次電流Ｉ２の指令値及び放電維持制御の終了時期を設定することができる。 According to such a configuration, it is possible to avoid that the energy input signals IGw1 and IGw2 are always high as shown in FIG. That is, the ignition of the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5 in the first cylinder group is not continuous, and the first cylinder # 1, the third cylinder # 3 in the first cylinder group It can suppress that the high periods of energy input signal IGw1 transmitted to 5th cylinder # 5 overlap. The ignition of the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6 in the second cylinder group is not continuous, and the second cylinder # 2, the fourth cylinder # 4, in the second cylinder group. It can suppress that the high periods of energy input signal IGw2 transmitted to 6th cylinder # 6 overlap. Therefore, even if the engine 60 is a multi-cylinder engine, the command value of the secondary current I2 and the end time of the discharge maintenance control can be set based on the energy input signals IGw1 and IGw2.
　なお、エンジン６０は、６気筒エンジンに限らず、８気筒エンジンや、１０気筒エンジン等であってもよい。また、エンジン６０の気筒を、３つ以上の気筒群に分けてもよい。そして、各気筒群の気筒が、点火プラグ２０による点火が連続しない気筒の集まりであればよい。具体的には、各気筒群（例えば第一気筒群）に含まれる２つの気筒で相前後して点火が行われる間に、他の気筒群（例えば第二気筒群）に含まれる気筒で点火が行われればよい。 The engine 60 is not limited to a 6-cylinder engine, and may be an 8-cylinder engine, a 10-cylinder engine, or the like. Further, the cylinders of the engine 60 may be divided into three or more cylinder groups. And the cylinder of each cylinder group should just be a collection of the cylinders by which ignition by the spark plug 20 does not continue. Specifically, ignition is performed in cylinders included in another cylinder group (for example, the second cylinder group) while ignition is performed in succession on two cylinders included in each cylinder group (for example, the first cylinder group). Should just be done.
　・図１，１６，１９，２０，２６のように点火信号ＩＧｔを伝達する信号線１本でエネルギ投入制御を行う場合は、図３６に示すように、上記点火信号ＩＧｔを及び上記エネルギ投入信号ＩＧｗに含まれる情報を、点火信号ＩＧｔのみに重畳させることもできる。すなわち、放電開始制御を開始してから、点火信号ＩＧｔの1回目の立ち上がりで第一制御信号により第一巻線１２Ｂへの通電を開始し、２回目の立ち上がりで第一巻線１２Ｂへの通電を終了する。そして、点火信号ＩＧｔの２回目の立ち下がりで放電維持制御を終了する。 When energy input control is performed with one signal line for transmitting the ignition signal IGt as shown in FIGS. 1, 16, 19, 20, and 26, the ignition signal IGt and the energy input signal are supplied as shown in FIG. Information included in IGw can be superimposed only on the ignition signal IGt. That is, after starting the discharge start control, energization to the first winding 12B is started by the first control signal at the first rise of the ignition signal IGt, and energization to the first winding 12B at the second rise. Exit. And discharge maintenance control is complete | finished by the 2nd fall of the ignition signal IGt.
　具体的には、図３７に示すように、点火制御回路３０は、信号情報切り分け回路３０ａ、第一制御部３０ｂ、エネルギ重畳制御部３０ｃ、第二制御部３０ｄ、第四制御部３０ｅ等を備えている。信号情報切り分け回路３０ａは、点火信号ＩＧｔの立ち上がり時期及び立下がり時期を検出し、立ち上がり回数及び立下がり回数をカウントする。第一制御部３０ｂ及び第四制御部３０ｅは、信号情報切り分け回路３０ａからの情報に基づいて、それぞれ第一制御信号及び第四制御信号を作成する。エネルギ重畳制御部３０ｃ及び第二制御部３０ｄは、信号情報切り分け回路３０ａからの情報及び検出した二次電流Ｉ２に基づいて、第二制御信号を作成する。詳しくは、日本国特許第４７３６９４２号公報に記載された構成を採用することができる。なお、上記点火信号ＩＧｔに基づく第一巻線１２Ｂへの通電期間の設定、並びに二次電流Ｉ２の指令値及び放電維持制御の終了時期の設定は、他の実施形態及びそれらの変更例にも適用することができる。 Specifically, as shown in FIG. 37, the ignition control circuit 30 includes a signal information separation circuit 30a, a first control unit 30b, an energy superposition control unit 30c, a second control unit 30d, a fourth control unit 30e, and the like. ing. The signal information dividing circuit 30a detects the rising timing and falling timing of the ignition signal IGt, and counts the number of rising times and the number of falling times. The first control unit 30b and the fourth control unit 30e create a first control signal and a fourth control signal, respectively, based on information from the signal information separation circuit 30a. The energy superposition control unit 30c and the second control unit 30d create a second control signal based on the information from the signal information separation circuit 30a and the detected secondary current I2. Specifically, the configuration described in Japanese Patent No. 4736942 can be employed. The setting of the energization period to the first winding 12B based on the ignition signal IGt and the setting of the command value of the secondary current I2 and the end timing of the discharge maintenance control are also applied to other embodiments and their modifications. Can be applied.
　・上記各実施形態において、ＭＯＳＦＥＴを想定していたスイッチング素子（第三スイッチング素子１４や第二スイッチング素子１６）は、ＭＯＳＦＥＴに代わり、ＩＧＢＴやパワートランジスタ、サイリスタ、トライアックなどを用いてもよい。同様に、ＩＧＢＴを想定していたスイッチング素子（第一スイッチング素子１５）は、ＭＯＳＦＥＴやパワートランジスタ、サイリスタ、トライアックなどを用いてもよい。 In the above embodiments, the switching elements (third switching element 14 and second switching element 16) that are assumed to be MOSFETs may use IGBTs, power transistors, thyristors, triacs, or the like instead of MOSFETs. Similarly, a MOSFET, a power transistor, a thyristor, a triac, or the like may be used as the switching element (first switching element 15) that is assumed to be an IGBT.
　・上記各実施形態において、第一スイッチング素子１５には、第五ダイオード１５Ｄ（図１に点線で例示）が逆並列に接続されていてもよい。仮に第一実施形態において、電流還流経路Ｌ１がない状態で放電維持制御を実施した場合、第二巻線１２Ｃへ流れる一次電流Ｉ１が第一スイッチング素子１５に逆並列に接続される第五ダイオード１５Ｄと、第一巻線１２Ｂと、を介して第二巻線１２Ｃから第二スイッチング素子１６へと流れる電流が還流することになる。この場合、還流する電流は第一巻線１２Ｂの影響を受けることでその電流の大きさが小さくなり、それに伴って二次コイル１３に生じる二次電流Ｉ２が小さくなるなど、その制御性が低下するおそれがある。この点、電流還流経路Ｌ１が設けられることで、放電維持制御中に電流還流経路Ｌ１を介して第二巻線１２Ｃへと電流が還流することになる。これにより、点火プラグ２０に流れる二次電流Ｉ２が小さくなることを抑制することができるため、第一スイッチング素子１５に第五ダイオード１５Ｄが逆並列に接続される構成に対して本点火システム１０は好適な構成といえる。 In the above embodiments, the first switching element 15 may be connected to the fifth diode 15D (illustrated by a dotted line in FIG. 1) in antiparallel. In the first embodiment, if the discharge maintenance control is performed without the current return path L1, the fifth diode 15D in which the primary current I1 flowing to the second winding 12C is connected to the first switching element 15 in antiparallel. Then, the current flowing from the second winding 12C to the second switching element 16 through the first winding 12B is circulated. In this case, the current flowing back is affected by the first winding 12B, so that the magnitude of the current is reduced, and the secondary current I2 generated in the secondary coil 13 is accordingly reduced. There is a risk. In this regard, by providing the current return path L1, current flows back to the second winding 12C via the current return path L1 during the discharge maintenance control. Accordingly, since the secondary current I2 flowing through the spark plug 20 can be suppressed from decreasing, the present ignition system 10 has a configuration in which the fifth diode 15D is connected to the first switching element 15 in antiparallel. This can be said to be a suitable configuration.
　・上記各実施形態では、２～３ｋＶの範囲内で放電維持電圧を設定していた。このことについて、例えば放電維持電圧をエンジン６０の燃焼状態に合わせて、３ｋＶよりも大きな値、又は２ｋＶよりも小さい値に設定してもよい。 In the above embodiments, the sustaining voltage is set within a range of 2 to 3 kV. In this regard, for example, the discharge sustain voltage may be set to a value larger than 3 kV or a value smaller than 2 kV in accordance with the combustion state of the engine 60.
　・第一実施形態及び第二実施形態では、カソード側が第二スイッチング素子１６に接続されており、アノード側が第二巻線１２Ｃにおける第二スイッチング素子１６側の端部に接続されている第三ダイオード１９が設けられていた。また、第三実施形態では、カソード側が接地側に接続されており、アノード側が第二巻線１２Ｃにおける中間タップ１２Ａ側とは反対側の端部に接続されている第三ダイオード１９が設けられていた。このことについて、第三ダイオード１９を設けない構成として、第二スイッチング素子１６や第三スイッチング素子１４に逆流防止機能を備えた素子（ダイオード）が備わっていてもよい。 In the first embodiment and the second embodiment, the third diode in which the cathode side is connected to the second switching element 16 and the anode side is connected to the end of the second winding 12C on the second switching element 16 side. 19 was provided. In the third embodiment, a third diode 19 is provided in which the cathode side is connected to the ground side and the anode side is connected to the end of the second winding 12C opposite to the intermediate tap 12A side. It was. In this regard, as a configuration in which the third diode 19 is not provided, the second switching element 16 or the third switching element 14 may be provided with an element (diode) having a backflow prevention function.
　・上記各実施形態では、点火制御回路３０は、エンジンＥＣＵから受信した点火信号ＩＧｔに基づいて各制御信号を生成して制御していたが、これに限定されるものではなく、各制御信号の内の任意の制御信号を個別にエンジンＥＣＵから受信して制御するようにしてもよい。 In each of the above embodiments, the ignition control circuit 30 generates and controls each control signal based on the ignition signal IGt received from the engine ECU, but the present invention is not limited to this. Any of these control signals may be individually received from the engine ECU and controlled.
　・上記各実施形態では、ケース５０内に電源部１７や点火プラグ２０を除く点火システム１０を収容していた。このことについて、ケース５０内に収容する点火システム１０の構成を減らしてもよい。例えば、点火制御回路３０を削除し、点火制御回路３０が実施する制御を、ケース５０の外部に存在するエンジンＥＣＵに実施させる構成としてもよい。この場合、エンジンＥＣＵが点火制御回路に該当することとなる。 In the above embodiments, the ignition system 10 excluding the power supply unit 17 and the spark plug 20 is housed in the case 50. About this, you may reduce the structure of the ignition system 10 accommodated in the case 50. FIG. For example, the ignition control circuit 30 may be deleted, and the control performed by the ignition control circuit 30 may be performed by an engine ECU that exists outside the case 50. In this case, the engine ECU corresponds to the ignition control circuit.
　・上記各実施形態では、電流還流経路にダイオードを設ける例（第一実施形態における電流還流経路Ｌ１の第一ダイオード１８などが該当）で説明したが、これに限定されるものではなく、例えば半導体スイッチ素子を設けて、還流動作のときに閉じるような開閉制御を実施してもよい。 In each of the embodiments described above, an example in which a diode is provided in the current return path (corresponding to the first diode 18 of the current return path L1 in the first embodiment, etc.) has been described. However, the present invention is not limited to this. A switch element may be provided to perform opening / closing control such that it is closed during the reflux operation.
　本開示は、実施例に準拠して記述されたが、本開示は当該実施例や構造に限定されるものではないと理解される。本開示は、様々な変形例や均等範囲内の変形をも包含する。加えて、様々な組み合わせや形態、さらには、それらに一要素のみ、それ以上、あるいはそれ以下、を含む他の組み合わせや形態をも、本開示の範疇や思想範囲に入るものである。 Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims (25)

  1. 　内燃機関（６０）の燃焼室内の可燃混合気に点火するための火花放電を発生する点火プラグ（２０）と、
    　一次コイル（１２）及び二次コイル（１３）を具備し、前記二次コイルにより前記点火プラグに電圧を印加する点火コイル（１１）と、
    　所定の電圧を前記一次コイルに印加する電圧印加部（１７）と、
    　前記一次コイルを成す巻線の途中には中間タップ（１２Ａ）が設けられており、前記電圧印加部から前記中間タップへと流れる一次電流の導通と遮断を行う第三スイッチング素子（１４）と、
    　前記一次コイルを成す巻線のうち前記中間タップから一端までの巻線である第一巻線（１２Ｂ）側の一端と接地側との間に接続される第一スイッチング素子（１５）と、
    　前記一次コイルを成す巻線のうち前記中間タップから他端までの巻線である第二巻線（１２Ｃ）側の一端と接地側との間に接続される第二スイッチング素子（１６）と、
    　前記第一スイッチング素子の開閉状態と、前記第二スイッチング素子の開閉状態と、前記第三スイッチング素子の開閉状態と、をそれぞれ制御することで、前記第一巻線へ流れる前記一次電流の導通と遮断を行い前記点火プラグに前記火花放電を発生させる放電発生制御と、前記第二巻線へ流れる前記一次電流の導通と遮断を行い前記点火プラグに生じている前記火花放電を維持する放電維持制御と、を行なう点火制御回路（３０）と、
    　前記第二巻線から前記第二スイッチング素子へと流れる電流を還流させる電流還流経路（Ｌ１）と、
    を備える内燃機関用点火システム。     An ignition plug (20) for generating a spark discharge for igniting a combustible mixture in a combustion chamber of the internal combustion engine (60);
    An ignition coil (11) comprising a primary coil (12) and a secondary coil (13), and applying a voltage to the spark plug by the secondary coil;
    A voltage application unit (17) for applying a predetermined voltage to the primary coil;
    An intermediate tap (12A) is provided in the middle of the winding forming the primary coil, and a third switching element (14) for conducting and blocking a primary current flowing from the voltage application unit to the intermediate tap,
    A first switching element (15) connected between one end on the first winding (12B) side, which is a winding from the intermediate tap to one end of the windings forming the primary coil, and the ground side;
    A second switching element (16) connected between one end on the second winding (12C) side which is a winding from the intermediate tap to the other end of the windings forming the primary coil and the ground side;
    By controlling the open / close state of the first switching element, the open / close state of the second switching element, and the open / close state of the third switching element, the conduction of the primary current flowing to the first winding is controlled. Discharge generation control for cutting off and generating the spark discharge in the spark plug, and discharge maintenance control for maintaining the spark discharge generated in the spark plug by conducting and blocking the primary current flowing to the second winding An ignition control circuit (30) for performing
    A current return path (L1) for returning a current flowing from the second winding to the second switching element;
    An internal combustion engine ignition system.
  2. 　前記電流還流経路（Ｌ１）は第一ダイオード（１８）を備え、前記第一ダイオードのカソード側は前記中間タップに接続されており、前記第一ダイオードのアノード側は接地側に接続されている請求項１に記載の内燃機関用点火システム。 The current return path (L1) includes a first diode (18), a cathode side of the first diode is connected to the intermediate tap, and an anode side of the first diode is connected to a ground side. Item 2. The ignition system for an internal combustion engine according to Item 1.
  3. 　前記点火制御回路は、前記第二スイッチング素子を開状態に制御した上で、前記第一スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる前記一次電流の導通と遮断を行い、前記第一スイッチング素子を開状態に制御した上で、前記第二スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第三スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う請求項１又は２に記載の内燃機関用点火システム。 The ignition control circuit controls the second switching element to an open state, controls the first switching element and the third switching element to a closed state, and then controls the first switching element to an open state. By conducting and interrupting the primary current flowing to the first winding, and controlling the first switching element to an open state, the second switching element and the third switching element are closed. The internal combustion engine ignition system according to claim 1 or 2, wherein the primary current flowing through the second winding is conducted and recirculated by controlling and then controlling the third switching element to an open state.
  4. 　前記点火制御回路は、前記第二スイッチング素子を開状態に制御した上で、前記第一スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる前記一次電流の導通と遮断を行い、前記第一スイッチング素子を開状態に制御した上で、前記第二スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第二スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と遮断を行う請求項１又は２に記載の内燃機関用点火システム。 The ignition control circuit controls the second switching element to an open state, controls the first switching element and the third switching element to a closed state, and then controls the first switching element to an open state. By conducting and interrupting the primary current flowing to the first winding, and controlling the first switching element to an open state, the second switching element and the third switching element are closed. The internal combustion engine ignition system according to claim 1 or 2, wherein the primary current flowing through the second winding is turned on and off by controlling the second switching element in an open state.
  5. 　内燃機関（６０）の燃焼室内の可燃混合気に点火するための火花放電を発生する点火プラグ（２０）と、
    　一次コイル（１２）及び二次コイル（１３）を具備し、前記二次コイルにより前記点火プラグに電圧を印加する点火コイル（１１）と、
    　前記一次コイルを成す巻線の途中には中間タップ（１２Ａ）が設けられており、所定の電圧を前記中間タップに印加する電圧印加部（１７）と、
    　前記一次コイルを成す巻線のうち前記中間タップから一端までの巻線である第一巻線（１２Ｂ）側の一端と接地側との間に接続される第一スイッチング素子（１５）と、
    　前記一次コイルを成す巻線のうち前記中間タップから他端までの巻線である第二巻線（１２Ｃ）側の一端と接地側との間に接続される第二スイッチング素子（１６）と、
    　前記第一スイッチング素子の開閉状態と、前記第二スイッチング素子の開閉状態と、をそれぞれ制御することで、前記第一巻線へ流れる一次電流の導通と遮断を行い前記点火プラグに前記火花放電を発生させる放電発生制御と、前記第二巻線へ流れる前記一次電流の導通と遮断を行い前記点火プラグに生じている前記火花放電を維持する放電維持制御と、を行なう点火制御回路（３０）と、
    　前記第二スイッチング素子の開閉動作により前記第二巻線に流れる電流を遮断したときに前記第二巻線に流れる電流を還流させる電流還流経路（Ｌ４）と、
    を備える内燃機関用点火システム。     An ignition plug (20) for generating a spark discharge for igniting a combustible mixture in a combustion chamber of the internal combustion engine (60);
    An ignition coil (11) comprising a primary coil (12) and a secondary coil (13), and applying a voltage to the spark plug by the secondary coil;
    An intermediate tap (12A) is provided in the middle of the winding forming the primary coil, and a voltage application unit (17) for applying a predetermined voltage to the intermediate tap;
    A first switching element (15) connected between one end on the first winding (12B) side, which is a winding from the intermediate tap to one end of the windings forming the primary coil, and the ground side;
    A second switching element (16) connected between one end on the second winding (12C) side which is a winding from the intermediate tap to the other end of the windings forming the primary coil and the ground side;
    By controlling the open / closed state of the first switching element and the open / closed state of the second switching element, the primary current flowing through the first winding is turned on and off, and the spark discharge is discharged to the spark plug. An ignition control circuit (30) for performing a discharge generation control to be generated and a discharge maintenance control for conducting and blocking the primary current flowing to the second winding and maintaining the spark discharge generated in the spark plug; ,
    A current return path (L4) for returning the current flowing through the second winding when the current flowing through the second winding is interrupted by the opening / closing operation of the second switching element;
    An internal combustion engine ignition system.
  6. 　前記電流還流経路は第二ダイオード（４１）を備え、前記第二ダイオードのカソード側は前記電圧印加部と前記中間タップとの間の電流経路（Ｌ６）に接続されており、前記第二ダイオードのアノード側は前記第二巻線と前記第二スイッチング素子との間の電流経路（Ｌ５）に接続されている請求項５に記載の内燃機関用点火システム。 The current return path includes a second diode (41), and a cathode side of the second diode is connected to a current path (L6) between the voltage application unit and the intermediate tap, The ignition system for an internal combustion engine according to claim 5, wherein the anode side is connected to a current path (L5) between the second winding and the second switching element.
  7. 　前記点火制御回路は、前記放電発生制御として、前記第二スイッチング素子を開状態に制御した上で、前記第一スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる一次電流の導通と遮断を行い、前記放電維持制御として、前記第一スイッチング素子を開状態に制御した上で、前記第二スイッチング素子を閉状態に制御し、そのあと前記第二スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う請求項５又は６に記載の内燃機関用点火システム。 The ignition control circuit controls the first switching element to the closed state after controlling the second switching element to the open state as the discharge generation control, and then controls the first switching element to the open state. As a result, the primary current flowing through the first winding is turned on and off, and as the discharge maintenance control, the first switching element is controlled to be open, and the second switching element is controlled to be closed. Then, the ignition system for an internal combustion engine according to claim 5 or 6, wherein the primary current flowing through the second winding is conducted and recirculated by controlling the second switching element to an open state.
  8. 　カソード側は前記第二スイッチング素子に接続されており、アノード側は前記中間タップ側とは反対側の端部に接続されている第三ダイオード（１９）を備える請求項１乃至７のいずれか１項に記載の内燃機関用点火システム。 The cathode side is connected to the second switching element, and the anode side includes a third diode (19) connected to an end opposite to the intermediate tap side. An ignition system for an internal combustion engine according to item.
  9. 　カソード側は前記中間タップに接続されており、アノード側は前記電圧印加部に接続されている第三ダイオード（１９）を備える請求項１乃至７のいずれか１項に記載の内燃機関用点火システム。 The ignition system for an internal combustion engine according to any one of claims 1 to 7, further comprising a third diode (19) having a cathode side connected to the intermediate tap and an anode side connected to the voltage application unit. .
  10. 　内燃機関（６０）の燃焼室内の可燃混合気に点火するための火花放電を発生する点火プラグ（２０）と、
    　一次コイル（１２）及び二次コイル（１３）を具備し、前記二次コイルにより前記点火プラグに電圧を印加する点火コイル（１１）と、
    　前記一次コイルを成す巻線の途中には中間タップ（１２Ａ）が設けられており、所定の電圧を前記中間タップに印加する電圧印加部（１７）と、
    　前記一次コイルを成す巻線のうち前記中間タップから一端までの巻線である第一巻線（１２Ｂ）側の一端と接地側との間に接続される第一スイッチング素子（１５）と、
    　前記中間タップと、前記中間タップから他端までの巻線である第二巻線と、の間に接続される第三スイッチング素子（１４）と、
    　前記第一スイッチング素子の開閉状態と、前記第三スイッチング素子の開閉状態と、をそれぞれ制御することで、前記点火プラグに前記火花放電を発生させる放電発生制御と、前記点火プラグに生じている前記火花放電を維持する放電維持制御と、を行なう点火制御回路（３０）と、
    　前記第二巻線から接地側へと流れる電流を還流させる電流還流経路（Ｌ７）と、
    を備える内燃機関用点火システム。     An ignition plug (20) for generating a spark discharge for igniting a combustible mixture in a combustion chamber of the internal combustion engine (60);
    An ignition coil (11) comprising a primary coil (12) and a secondary coil (13), and applying a voltage to the spark plug by the secondary coil;
    An intermediate tap (12A) is provided in the middle of the winding forming the primary coil, and a voltage application unit (17) for applying a predetermined voltage to the intermediate tap;
    A first switching element (15) connected between one end on the first winding (12B) side, which is a winding from the intermediate tap to one end of the windings forming the primary coil, and the ground side;
    A third switching element (14) connected between the intermediate tap and a second winding that is a winding from the intermediate tap to the other end;
    Discharge generation control for causing the spark plug to generate the spark discharge by controlling the open / close state of the first switching element and the open / close state of the third switching element, respectively, and the spark plug generated in the spark plug An ignition control circuit (30) for performing discharge maintenance control for maintaining spark discharge;
    A current return path (L7) for returning the current flowing from the second winding to the ground side;
    An internal combustion engine ignition system.
  11. 　前記電流還流経路は第四ダイオード（４２）を備え、前記第四ダイオードのカソード側は前記第三スイッチング素子と前記第二巻線との間の電流経路（Ｌ８）に接続されており、前記第四ダイオードのアノード側は接地側に接続されている請求項１０に記載の内燃機関用点火システム。 The current return path includes a fourth diode (42), and a cathode side of the fourth diode is connected to a current path (L8) between the third switching element and the second winding. The ignition system for an internal combustion engine according to claim 10, wherein the anode side of the four diodes is connected to the ground side.
  12. 　カソード側は接地側に接続されており、アノード側は前記第二巻線における前記中間タップ側とは反対側の端部に接続されている第三ダイオード（１９）を備える請求項１０又は１１に記載の内燃機関用点火システム。 The cathode side is connected to the ground side, and the anode side includes a third diode (19) connected to an end of the second winding opposite to the intermediate tap side. An ignition system for an internal combustion engine as described.
  13. 　カソード側は前記第二巻線における前記中間タップ側の端部に接続されており、アノード側は前記第三スイッチング素子に接続されている第三ダイオード（１９）を備える請求項１０又は１１に記載の内燃機関用点火システム。 The cathode side is connected to the end of the intermediate tap side in the second winding, and the anode side includes a third diode (19) connected to the third switching element. Ignition system for internal combustion engines.
  14. 　前記点火制御回路は、前記放電発生制御として、前記第三スイッチング素子を開状態に制御した上で、前記第一スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子を開状態に制御することで、前記第一巻線へ流れる一次電流の導通と遮断を行い、前記放電維持制御として、前記第一スイッチング素子を開状態に制御した上で、前記第三スイッチング素子を閉状態に制御し、そのあと前記第三スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う請求項１０乃至１３のいずれか１項に記載の内燃機関用点火システム。 The ignition control circuit controls the first switching element to the closed state after controlling the third switching element to the open state as the discharge generation control, and then controls the first switching element to the open state. As a result, the primary current flowing to the first winding is turned on and off, and as the discharge maintenance control, the first switching element is controlled to be in an open state, and then the third switching element is controlled to be in a closed state. The internal current engine according to any one of claims 10 to 13, wherein the primary current flowing through the second winding is conducted and recirculated by controlling the third switching element to open. Ignition system.
  15. 　前記点火制御回路は、前記放電発生制御として、前記第一スイッチング素子及び前記第三スイッチング素子を閉状態に制御し、そのあと前記第一スイッチング素子及び前記第三スイッチング素子を開状態に制御することで、前記第一巻線及び前記第二巻線へと流れる一次電流の導通と遮断を行い、前記放電維持制御として、前記第一スイッチング素子を開状態に制御した上で、前記第三スイッチング素子を閉状態に制御し、そのあと前記第三スイッチング素子を開状態に制御することで、前記第二巻線へ流れる前記一次電流の導通と還流を行う請求項１０乃至１３のいずれか１項に記載の内燃機関用点火システム。 The ignition control circuit controls the first switching element and the third switching element to a closed state as the discharge generation control, and then controls the first switching element and the third switching element to an open state. Then, the primary current flowing to and from the first winding and the second winding is turned on and off, and as the discharge maintenance control, the first switching element is controlled in an open state, and then the third switching element 14. The method according to any one of claims 10 to 13, wherein the primary current flowing to the second winding is conducted and refluxed by controlling the first switching element to a closed state and then controlling the third switching element to an open state. An ignition system for an internal combustion engine as described.
  16. 　前記第一巻線の巻数は、前記第二巻線の巻数よりも多い請求項１乃至１５のいずれか１項に記載の内燃機関用点火システム。 The internal combustion engine ignition system according to any one of claims 1 to 15, wherein the number of turns of the first winding is greater than the number of turns of the second winding.
  17. 　前記二次コイルの巻数を前記第二巻線の巻数で割った値である巻数比が、前記放電発生制御により前記点火プラグに発生させた前記火花放電を維持するために必要な電圧としての放電維持電圧を、前記電圧印加部が印加する前記電圧で割った値である電圧比よりも大きくなるように構成される請求項１乃至１６のいずれか１項に記載の内燃機関用点火システム。 Discharge as a voltage necessary for maintaining the spark discharge generated in the spark plug by the discharge generation control, wherein the turn ratio is a value obtained by dividing the number of turns of the secondary coil by the number of turns of the second winding. The ignition system for an internal combustion engine according to any one of claims 1 to 16, wherein the ignition system is configured to be larger than a voltage ratio that is a value obtained by dividing a sustain voltage by the voltage applied by the voltage application unit.
  18. 　前記点火プラグに流れる二次電流を検出する二次電流検出部（Ｌ２，３０）を備え、
    　前記点火制御回路は、前記放電維持制御を実施している期間中、前記二次電流検出部により検出された前記二次電流の絶対値が第一閾値よりも小さくなった場合に、前記第三スイッチング素子を閉状態に制御し、前記二次電流検出部により検出された前記二次電流の絶対値が前記第一閾値よりも大きく設定された第二閾値よりも大きくなった場合に、前記第三スイッチング素子を開状態に制御する請求項３，１４，１５のいずれか１項に記載の内燃機関用点火システム。     A secondary current detector (L2, 30) for detecting a secondary current flowing through the spark plug;
    When the absolute value of the secondary current detected by the secondary current detection unit becomes smaller than a first threshold during the period when the discharge maintenance control is performed, the ignition control circuit When the switching element is controlled to be in a closed state, and the absolute value of the secondary current detected by the secondary current detection unit is larger than a second threshold set larger than the first threshold, the first The internal combustion engine ignition system according to any one of claims 3, 14, and 15, wherein the three switching elements are controlled to be in an open state.
  19. 　前記点火プラグに流れる二次電流を検出する二次電流検出部（Ｌ２，３０）を備え、
    　前記点火制御回路は、前記放電維持制御を実施している期間中、前記二次電流検出部により検出された前記二次電流の絶対値が第一閾値よりも小さくなった場合に、前記第二スイッチング素子を閉状態に制御し、前記二次電流検出部により検出された前記二次電流の絶対値が前記第一閾値よりも大きく設定された第二閾値よりも大きくなった場合に、前記第二スイッチング素子を開状態に制御する請求項４又は７に記載の内燃機関用点火システム。     A secondary current detector (L2, 30) for detecting a secondary current flowing through the spark plug;
    When the absolute value of the secondary current detected by the secondary current detection unit is smaller than a first threshold during the period when the discharge maintenance control is being performed, the ignition control circuit When the switching element is controlled to be in a closed state, and the absolute value of the secondary current detected by the secondary current detection unit is larger than a second threshold set larger than the first threshold, the first The ignition system for an internal combustion engine according to claim 4 or 7, wherein the two switching elements are controlled to be in an open state.
  20. 　前記第一スイッチング素子と、前記第二スイッチング素子と、前記第三スイッチング素子と、前記点火制御回路と、前記電流還流経路とは、前記点火コイルが収納されているケース（５０）内に収容される請求項１乃至４のいずれか１項に記載の内燃機関用点火システム。 The first switching element, the second switching element, the third switching element, the ignition control circuit, and the current return path are accommodated in a case (50) in which the ignition coil is accommodated. The ignition system for an internal combustion engine according to any one of claims 1 to 4.
  21. 　前記第一スイッチング素子と、前記第二スイッチング素子と、前記点火制御回路と、前記電流還流経路とは、前記点火コイルが収納されているケース（５０）内に収容される請求項５乃至７のいずれか１項に記載の内燃機関用点火システム。 The first switching element, the second switching element, the ignition control circuit, and the current return path are accommodated in a case (50) in which the ignition coil is accommodated. An ignition system for an internal combustion engine according to any one of the preceding claims.
  22. 　前記第一スイッチング素子と、前記第三スイッチング素子と、前記点火制御回路と、前記電流還流経路とは、前記点火コイルが収納されているケース（５０）内に収容される請求項１０乃至１５のいずれか１項に記載の内燃機関用点火システム。 The first switching element, the third switching element, the ignition control circuit, and the current return path are accommodated in a case (50) in which the ignition coil is accommodated. An ignition system for an internal combustion engine according to any one of the preceding claims.
  23. 　前記第一スイッチング素子には、第五ダイオード（１５Ｄ）が逆並列に接続されている請求項１乃至２２のいずれか１項に記載の内燃機関用点火システム。 The internal combustion engine ignition system according to any one of claims 1 to 22, wherein a fifth diode (15D) is connected in antiparallel to the first switching element.
  24. 　前記内燃機関は、多気筒内燃機関であり、
    　前記点火制御回路は、前記内燃機関の各気筒に設けられており、
    　前記放電維持制御において前記二次コイルに流れる電流を制御する電流制御信号を出力する制御装置（６１）を備え、
    　前記制御装置には、前記電流制御信号を伝達する第一共通信号線（５２）及び第二共通信号線（５３）が接続されており、
    　前記第一共通信号線から分岐した各信号線（５２ａ～５２ｃ）が、前記点火プラグによる点火が連続しない気筒（＃１、＃３、＃５）の集まりである第一気筒群の各気筒の前記点火制御回路に接続され、
    　前記第二共通信号線から分岐した各信号線（５３ａ～５３ｃ）が、前記点火プラグによる点火が連続しない気筒（＃２、＃４、＃６）の集まりであり且つ前記第一気筒群に含まれない気筒の集まりである第二気筒群の各気筒の前記点火制御回路に接続されている請求項１乃至２３のいずれか１項に記載の内燃機関用点火システム。     The internal combustion engine is a multi-cylinder internal combustion engine;
    The ignition control circuit is provided in each cylinder of the internal combustion engine,
    A controller (61) for outputting a current control signal for controlling a current flowing through the secondary coil in the discharge maintenance control;
    A first common signal line (52) and a second common signal line (53) for transmitting the current control signal are connected to the control device,
    Each signal line (52a to 52c) branched from the first common signal line is a group of cylinders (# 1, # 3, # 5) in which ignition by the spark plug does not continue. Connected to the ignition control circuit;
    Each signal line (53a to 53c) branched from the second common signal line is a group of cylinders (# 2, # 4, # 6) in which ignition by the spark plug does not continue and is included in the first cylinder group The ignition system for an internal combustion engine according to any one of claims 1 to 23, wherein the ignition system is connected to the ignition control circuit of each cylinder of the second cylinder group, which is a group of cylinders that are not capable of operating.
  25. 　前記第一気筒群に含まれる２つの気筒で相前後して前記点火が行われる間に、前記第二気筒群に含まれる１つの気筒で前記点火が行われる請求項２４に記載の内燃機関用点火システム。 25. The internal combustion engine according to claim 24, wherein the ignition is performed in one cylinder included in the second cylinder group while the ignition is performed in succession in two cylinders included in the first cylinder group. Ignition system.
PCT/JP2018/015045 2017-04-20 2018-04-10 Internal combustion engine ignition system WO2018193909A1 (en)

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