WO2022180906A1 - Method for detecting in-cylinder pressure, method for diagnosing in-cylinder pressure sensor, and internal combustion engine control device - Google Patents

Method for detecting in-cylinder pressure, method for diagnosing in-cylinder pressure sensor, and internal combustion engine control device Download PDF

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Publication number
WO2022180906A1
WO2022180906A1 PCT/JP2021/034946 JP2021034946W WO2022180906A1 WO 2022180906 A1 WO2022180906 A1 WO 2022180906A1 JP 2021034946 W JP2021034946 W JP 2021034946W WO 2022180906 A1 WO2022180906 A1 WO 2022180906A1
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WIPO (PCT)
Prior art keywords
cylinder pressure
coil
discharge
internal combustion
combustion engine
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PCT/JP2021/034946
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French (fr)
Japanese (ja)
Inventor
英一郎 大畠
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日立Astemo株式会社
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Application filed by 日立Astemo株式会社 filed Critical 日立Astemo株式会社
Priority to CN202180077297.XA priority Critical patent/CN116507801A/en
Priority to JP2023502049A priority patent/JP7324384B2/en
Publication of WO2022180906A1 publication Critical patent/WO2022180906A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D45/00—Electrical control not provided for in groups F02D41/00 - F02D43/00
    • 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
    • F02P17/00—Testing of ignition installations, e.g. in combination with adjusting; Testing of ignition timing in compression-ignition engines
    • 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
    • F02P3/02—Other installations having inductive energy storage, e.g. arrangements of induction coils
    • F02P3/04—Layout of circuits
    • F02P3/05—Layout of circuits for control of the magnitude of the current in the ignition coil
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M15/00—Testing of engines
    • G01M15/02—Details or accessories of testing apparatus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M15/00—Testing of engines
    • G01M15/04—Testing internal-combustion engines
    • G01M15/08—Testing internal-combustion engines by monitoring pressure in cylinders

Definitions

  • the present invention relates to an in-cylinder pressure detection method, an in-cylinder pressure sensor diagnosis method, and an internal combustion engine control device.
  • combustion control for each cylinder is required in accordance with the component characteristics of each cylinder.
  • Patent Document 1 discloses a relational expression between ignition discharge and in-cylinder pressure (p). According to this relational expression, the in-cylinder pressure (p) can be calculated from the discharge voltage (V), the discharge current (I), and the discharge path length (l).
  • An object of the present invention is to accurately detect the in-cylinder pressure (p) without being affected by the extension of the discharge path in consideration of the above problems.
  • the in-cylinder pressure detection method of the present invention includes a primary side coil and a secondary side coil in which an electromotive force is generated when energization of the primary side coil is interrupted.
  • In-cylinder pressure is detected using information of a secondary side coil in an internal combustion engine having a coil and an ignition plug connected to the secondary side coil.
  • This in-cylinder pressure detection method removes high-frequency components from the discharge waveform of the secondary coil, acquires information on the secondary current and secondary voltage from the discharge waveform from which the high-frequency components have been removed, and obtains information on the secondary current and secondary voltage from the following equation (1). Calculate the in-cylinder pressure.
  • V2 is the secondary voltage
  • I2 is the secondary current
  • p is the cylinder pressure
  • p0 the atmospheric pressure
  • l is the length of the discharge path.
  • the in-cylinder pressure (p) can be accurately detected without being affected by the expansion of the discharge path. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.
  • FIG. 1 is an overall configuration diagram showing a basic configuration example of an internal combustion engine according to an embodiment of the present invention
  • FIG. 1 is a partially enlarged view illustrating a spark plug according to an embodiment of the invention
  • FIG. 1 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to an embodiment of the present invention
  • FIG. 4 is a diagram for explaining the relationship between the operating state of the internal combustion engine and the gas flow velocity around the spark plug according to one embodiment of the present invention
  • 4A and 4B are diagrams for explaining the relationship between the discharge path and the flow velocity between the electrodes of the spark plug according to one embodiment of the present invention
  • It is a figure explaining an electric circuit containing an ignition coil concerning one embodiment of the present invention.
  • FIG. 1 is an overall configuration diagram showing a basic configuration example of an internal combustion engine according to an embodiment of the present invention
  • FIG. 1 is a partially enlarged view illustrating a spark plug according to an embodiment of the invention
  • FIG. 1 is a functional block diagram illustrating the functional configuration
  • FIG. 4 is a diagram showing an example of evaluation of accuracy of in-cylinder pressure (p) calculated using only a relational expression;
  • FIG. 4 is a diagram illustrating an example of frequency components of in-cylinder pressure;
  • 4 is a flowchart showing the procedure of in-cylinder pressure detection processing according to the embodiment of the present invention;
  • FIG. 4 is a diagram showing an example of evaluation of detection accuracy of in-cylinder pressure (p) according to one embodiment of the present invention.
  • FIG. 1 is an overall configuration diagram showing a basic configuration example of an internal combustion engine according to an embodiment of the present invention.
  • the internal combustion engine 100 shown in FIG. 1 may have a single cylinder or multiple cylinders, but in the embodiment, the internal combustion engine 100 having four cylinders will be described as an example.
  • air sucked from the outside flows through air cleaner 110 , intake pipe 111 , and intake manifold 112 . Air passing through the intake manifold 112 flows into each cylinder 150 when the intake valve 151 is opened. The amount of air flowing into each cylinder 150 is adjusted by the throttle valve 113 . The amount of air adjusted by throttle valve 113 is measured by flow rate sensor 114 .
  • the throttle valve 113 is provided with a throttle opening sensor 113a that detects the opening of the throttle.
  • the opening degree information of the throttle valve 113 detected by the throttle opening degree sensor 113 a is output to a control device (Electronic Control Unit: ECU) 1 .
  • ECU Electronic Control Unit
  • an electronic throttle valve driven by an electric motor is applied as the throttle valve 113 .
  • any other method may be applied as long as it can appropriately adjust the air flow rate.
  • the temperature of the gas that has flowed into each cylinder 150 is detected by the intake air temperature sensor 115 .
  • crank angle sensor 121 is provided radially outside the ring gear 120 attached to the crankshaft 123 .
  • Crank angle sensor 121 detects the rotation angle of crankshaft 123 .
  • the crank angle sensor 121 detects the rotation angle of the crankshaft 123 every 10 degrees and every combustion cycle.
  • a water temperature sensor 122 is provided in the water jacket (not shown) of the cylinder head.
  • a water temperature sensor 122 detects the temperature of the cooling water of the internal combustion engine 100 .
  • the vehicle is also provided with an accelerator position sensor (APS) 126 that detects the amount of displacement (depression amount) of the accelerator pedal 125 .
  • An accelerator position sensor 126 detects the torque requested by the driver.
  • the driver's requested torque detected by the accelerator position sensor 126 is output to the control device 1, which will be described later.
  • the control device 1 controls the throttle valve 113 based on this required torque.
  • the fuel stored in the fuel tank 130 is sucked and pressurized by the fuel pump 131 .
  • Fuel sucked and pressurized by the fuel pump 131 is adjusted to a predetermined pressure by a pressure regulator 132 provided in the fuel pipe 133 .
  • Fuel adjusted to a predetermined pressure is injected into each cylinder 150 from a fuel injection device (injector) 134 . Excess fuel after pressure regulation by the pressure regulator 132 is returned to the fuel tank 130 via a return pipe (not shown).
  • the control of the fuel injection device 134 is performed based on the fuel injection pulse (control signal) of the fuel injection control section 82 of the control device 1, which will be described later.
  • An exhaust valve 152 and an exhaust manifold 160 are attached to each cylinder 150 .
  • exhaust valve 152 When exhaust valve 152 is opened, exhaust gas is discharged from cylinder 150 to exhaust manifold 160 .
  • the exhaust manifold 160 discharges gas (exhaust gas) after combustion to the outside of the cylinder 150 .
  • a three-way catalyst 161 is provided on the exhaust side of the exhaust manifold 160 .
  • the three-way catalyst 161 purifies exhaust gas.
  • the exhaust gas purified by the three-way catalyst 161 is discharged into the atmosphere.
  • An upstream air-fuel ratio sensor 162 is provided upstream of the three-way catalyst 161 .
  • the upstream air-fuel ratio sensor 162 continuously detects the air-fuel ratio of exhaust gas discharged from each cylinder 150 .
  • a downstream side air-fuel ratio sensor 163 is provided downstream of the three-way catalyst 161 .
  • the downstream air-fuel ratio sensor 163 outputs a switch-like detection signal near the stoichiometric air-fuel ratio.
  • the downstream air-fuel ratio sensor 163 of this embodiment is an O2 sensor.
  • a spark plug 200 is provided at the top of each cylinder 150 .
  • the spark plug 200 generates a spark by electric discharge (ignition), and the spark ignites the air-fuel mixture in the cylinder 150 . This causes an explosion in cylinder 150 and pushes down piston 170 . As the piston 170 is pushed down, the crankshaft 123 rotates.
  • An ignition coil 300 that generates electrical energy (voltage) to be supplied to the ignition plug 200 is connected to the ignition plug 200 .
  • Output signals from various sensors such as the throttle opening sensor 113a, the flow rate sensor 114, the crank angle sensor 121, the accelerator position sensor 126, the water temperature sensor 122, etc. are output to the control device 1.
  • the control device 1 detects the operating state of the internal combustion engine 100 based on output signals from these various sensors.
  • the control device 1 controls the amount of air sent into the cylinder 150, the amount of fuel injected from the fuel injection device 134, the ignition timing of the spark plug 200, and the like.
  • spark plug 200 will be described with reference to FIG.
  • FIG. 2 is a partially enlarged view for explaining spark plug 200. As shown in FIG.
  • the spark plug 200 has a center electrode 210 and an outer electrode 220. As shown in FIG. Center electrode 210 is supported by a plug base (not shown) via insulator 230 . Thereby, the center electrode 210 is insulated. Outer electrode 220 is grounded.
  • a predetermined voltage eg, 20,000 V to 40,000 V in this embodiment
  • a predetermined voltage eg, 20,000 V to 40,000 V in this embodiment
  • discharge occurs between center electrode 210 and outer electrode 220 .
  • a spark generated by the discharge ignites the air-fuel mixture in the cylinder 150 .
  • the voltage at which electrical discharge (ignition) occurs due to dielectric breakdown of the gas components in the cylinder 150 depends on the state of the gas existing between the center electrode 210 and the outer electrode 220 and the internal pressure of the cylinder 150. Varies accordingly. The voltage at which this discharge occurs is called dielectric breakdown voltage.
  • the discharge control (ignition control) of the spark plug 200 is performed by an ignition control section 83 of the control device 1, which will be described later.
  • control device 1 includes an analog input section 10, a digital input section 20, an A/D (Analog/Digital) conversion section 30, a RAM (Random Access Memory) 40, and an MPU (Micro- Processing Unit) 50 , ROM (Read Only Memory) 60 , I/O (Input/Output) port 70 , and output circuit 80 .
  • analog input section 10 a digital input section 20
  • A/D (Analog/Digital) conversion section 30 a RAM (Random Access Memory) 40
  • MPU Micro- Processing Unit
  • ROM Read Only Memory
  • I/O Input/Output
  • Analog output signals from various sensors such as the throttle opening sensor 113a, the flow rate sensor 114, the accelerator position sensor 126, the upstream side air-fuel ratio sensor 162, the downstream side air-fuel ratio sensor 163, the water temperature sensor 122, etc. are input to the analog input unit 10. be done.
  • An A/D conversion section 30 is connected to the analog input section 10 .
  • Analog output signals from various sensors input to the analog input unit 10 are subjected to signal processing such as noise removal, and then converted to digital signals by the A/D conversion unit 30 .
  • the digital signal converted by the A/D converter 30 is stored in the RAM 40 .
  • a digital output signal from the crank angle sensor 121 is input to the digital input unit 20 .
  • An I/O port 70 is connected to the digital input section 20 .
  • a digital output signal input to the digital input section 20 is stored in the RAM 40 via the I/O port 70 .
  • Each output signal stored in the RAM 40 is arithmetically processed by the MPU 50.
  • the MPU 50 By executing a control program (not shown) stored in the ROM 60, the MPU 50 arithmetically processes the output signals stored in the RAM 40 according to the control program.
  • the MPU 50 calculates a control value that defines the actuation amount of each actuator (for example, the throttle valve 113, the pressure regulator 132, the spark plug 200, etc.) that drives the internal combustion engine 100 according to the control program, and temporarily stores the control value in the RAM 40. memorize.
  • a control value that defines the actuation amount of the actuator stored in the RAM 40 is output to the output circuit 80 via the I/O port 70 .
  • the output circuit 80 includes an overall control section 81 (see FIG. 3) that performs overall control of the internal combustion engine based on output signals from various sensors (for example, the accelerator position sensor 126), and a plunger rod (non-reactive) of the fuel injector 134. 3) for controlling the driving of the fuel injection control unit 82 (see FIG. 3) and an ignition control unit 83 (see FIG. 3) for controlling the voltage applied to the spark plug 200.
  • an overall control section 81 that performs overall control of the internal combustion engine based on output signals from various sensors (for example, the accelerator position sensor 126), and a plunger rod (non-reactive) of the fuel injector 134. 3) for controlling the driving of the fuel injection control unit 82 (see FIG. 3) and an ignition control unit 83 (see FIG. 3) for controlling the voltage applied to the spark plug 200.
  • FIG. 3 is a functional block diagram illustrating the functional configuration of the control device 1.
  • Each function of the control device 1 is realized as various functions in the output circuit 80 by the MPU 50 executing the control program stored in the ROM 60.
  • Various functions of the output circuit 80 include, for example, control of the fuel injection device 134 by the fuel injection control section 82 and discharge control of the spark plug 200 by the ignition control section 83 .
  • the output circuit 80 of the control device 1 has a general control section 81, a fuel injection control section 82, and an ignition control section 83.
  • the overall control unit 81 is connected to the accelerator position sensor 126 and receives the requested torque (acceleration signal S1) from the accelerator position sensor 126.
  • FIG. The overall control unit 81 detects the in-cylinder pressure (p) through in-cylinder pressure detection processing, which will be described later.
  • General control unit 81 controls overall fuel injection control unit 82 and ignition control unit 83 based on the required torque (acceleration signal S1) from accelerator position sensor 126 and the detected in-cylinder pressure (p). I do.
  • the fuel injection control unit 82 includes a cylinder discrimination unit 84 that discriminates each cylinder 150 of the internal combustion engine 100, an angle information generation unit 85 that measures the crank angle of the crankshaft 123, and a rotation speed information generation unit that measures the engine speed. 86 and .
  • Fuel injection control unit 82 receives cylinder identification information S3 from cylinder identification unit 84, crank angle information S4 from angle information generation unit 85, and engine speed information S5 from rotation speed information generation unit 86.
  • the fuel injection control unit 82 also includes an intake air amount measurement unit 87 that measures the amount of air taken into the cylinder 150, a load information generation unit 88 that measures the engine load, and a temperature of the engine cooling water. It is connected to the water temperature measurement part 89 and.
  • the fuel injection control unit 82 receives intake air amount information S6 from the intake air amount measuring unit 87, engine load information S7 from the load information generating unit 88, and cooling water temperature information S8 from the water temperature measuring unit 89.
  • the fuel injection control unit 82 calculates the injection amount and the injection time of the fuel injected from the fuel injection device 134 based on the received information. Then, the fuel injection control unit 82 transmits a fuel injection pulse S9 generated based on the calculated fuel injection amount and injection time to the fuel injection device 134 .
  • the ignition control unit 83 is connected not only to the overall control unit 81 but also to a cylinder discrimination unit 84, an angle information generation unit 85, a rotation speed information generation unit 86, a load information generation unit 88, and a water temperature measurement unit 89. and accept each information from them.
  • the ignition control unit 83 controls the amount of current (energization angle) to be energized to the primary coil 310 (see FIG. 8) of the ignition coil 300, the energization start time, and the current to the primary coil 310. Calculate the time (ignition time) to cut off the applied current.
  • the ignition control unit 83 outputs an energization signal SA to the primary coil 310 of the ignition coil 300 based on the calculated energization amount, energization start time, and ignition time, thereby controlling discharge by the spark plug 200 ( ignition control).
  • FIG. 4 is a diagram for explaining the relationship between the operating state of internal combustion engine 100 and the flow velocity of gas around spark plug 200. As shown in FIG.
  • the EGR rate is set, for example, as shown in FIG. 4 according to the relationship between the engine speed and the load. It should be noted that as the high EGR region in which the EGR rate is set higher is expanded, the fuel consumption and exhaust emissions can be reduced. However, in the high EGR region, the flame kernel is less likely to grow, and the spark plug 200 is more likely to cause poor ignition.
  • FIGS. 5A and 5B are diagrams for explaining the relationship between the discharge path between the electrodes of the spark plug and the flow velocity.
  • a discharge path 211 is formed between 220 .
  • a flame kernel grows and burns. Since the discharge path 211 moves under the influence of the gas flow between the electrodes 210 and 220, as shown in FIG. 5A, the higher the gas flow rate, the longer the discharge path 211 is formed in a short time. On the other hand, as shown in FIG. 5B, the lower the gas flow rate, the shorter the discharge path 211 becomes.
  • the flame kernel is less likely to grow. Therefore, it is necessary to increase the chances of the combustible gas coming into contact with the discharge path 211 .
  • the discharge path 211 is created by breaking the gas insulation. Therefore, if the current required to maintain the discharge path 211 is constant, it is necessary to supply power corresponding to the length of the discharge path 211 to maintain the discharge path 211 .
  • the energization control of the ignition coil 300 is performed so that a large amount of electric power is output from the ignition coil 300 to the spark plug 200 in a short period of time. Thereby, a long discharge path 211 as shown in FIG. 5A can be formed. As a result, the discharge path 211 can obtain contact opportunities with gas in a wide space.
  • the energization control of the ignition coil 300 is performed so that the ignition coil 300 continues to output a small electric power to the ignition plug 200 for a long time.
  • formation of a short discharge path 211 as shown in FIG. 5B can be maintained.
  • the discharge path 211 can obtain contact opportunities with the gas passing near the electrodes of the spark plug 200 for a longer period of time.
  • FIG. 6 is a diagram illustrating an electric circuit including an ignition coil according to one embodiment.
  • An electric circuit 400 shown in FIG. 6 has an ignition coil 300 .
  • Ignition coil 300 includes a primary coil 310 wound with a predetermined number of turns and a secondary coil 320 wound with a larger number of turns than primary coil 310 .
  • One end of the primary coil 310 is connected to the DC power supply 330 . Thereby, a predetermined voltage (for example, 12 V) is applied to the primary coil 310 .
  • the other end of the primary coil 310 is connected to a collector (C) terminal of an igniter (energization control circuit) 340 and grounded via the igniter 340 .
  • a transistor, a field effect transistor (FET), or the like is used for the igniter 340 .
  • a base (B) terminal of the igniter 340 is connected to the ignition control section 83 .
  • the energization signal SA output from the ignition control unit 83 is input to the base (B) terminal of the igniter 340 .
  • the collector (C) terminal and the emitter (E) terminal of the igniter 340 become energized, and the collector (C) terminal and the emitter (E) terminal become energized.
  • the energization signal SA is output from the ignition control unit 83 to the primary coil 310 of the ignition coil 300 via the igniter 340 .
  • a current flows through the primary coil 310 and electric power (electrical energy) is accumulated.
  • a voltage detection unit that detects secondary voltage and a current detection unit that detects secondary current are provided between spark plug 200 and secondary coil 320 .
  • the high voltage generated in the secondary coil 320 is applied to the center electrode 210 of the spark plug 200 (see FIGS. 5A and 5B). Thereby, a potential difference is generated between the center electrode 210 and the outer electrode 220 of the spark plug 200 .
  • the potential difference generated between the center electrode 210 and the outer electrode 220 becomes equal to or higher than the dielectric breakdown voltage Vm of the gas (air mixture in the cylinder 150)
  • the gas component breaks down and the center electrode 210 and the outer electrode 220 are separated. Discharge occurs during As a result, the fuel (air-fuel mixture) is ignited.
  • the ignition control unit 83 controls the energization of the ignition coil 300 by operating the electric circuit 400 as described above using the energization signal SA.
  • V2 is the secondary voltage
  • I2 is the secondary current
  • p is the cylinder pressure
  • p0 is the atmospheric pressure
  • l is the length of the discharge path. Therefore, V 2 , I 2 , p, l are variables and p 0 is a fixed value.
  • Equation (2) V 2 is calculated from l, I 2 , p, p 0 .
  • Equation (3) Equation (3) is the same as Equation (1) above.
  • FIG. 7 is a diagram showing an example of evaluating the accuracy of the in-cylinder pressure (p) calculated using only the above equation (5).
  • the horizontal axis of each graph shown in FIG. 7 represents the time [msec] after the start of discharge.
  • the vertical axis of each graph shown in FIG. 7 represents secondary current (I 2 ) [A], secondary voltage (V 2 ) [kV], and in-cylinder pressure (p) [kPa].
  • the solid lines representing the secondary current (I 2 ), secondary voltage (V 2 ) and in-cylinder pressure (p) are measured values.
  • the actual values are measured by extending the discharge period by using two ignition coils to continuously discharge with a time difference. As a result, the measurable period can be lengthened, and the combustion index can be calculated from more information.
  • the dashed line indicating the in-cylinder pressure (p) is the calculated value calculated using the above equation (5). Specifically, the length (l) of the discharge path is the distance between the electrodes, and the measured values of the secondary current (I 2 ) and the secondary voltage (V 2 ) are substituted into the relational expression. This is the in-cylinder pressure (p).
  • a solid line indicating the in-cylinder pressure (p) is an actual measurement of the in-cylinder pressure (p) using a combustion pressure sensor.
  • the waveforms of the secondary current (I 2 ) and secondary voltage (V 2 ) show fluctuations due to extension of the discharge path and re-discharge.
  • the calculated value (dashed line) of the in-cylinder pressure (p) repeatedly deviates from and coincides with the measured value (solid line). It is considered that the above equation (5), that is, the relational expression of KIM holds true when the discharge path is formed with the shortest distance between the electrodes at the start of redischarge. After discharge, the discharge path expands under the influence of the gas flow in the cylinder, so it is considered that the in-cylinder pressure calculated by the above equation (5) deviates from the actually measured in-cylinder pressure. Therefore, when calculating the in-cylinder pressure (p) simply by using the above equation (5), there is a problem that the accuracy is lowered.
  • FIG. 8 is a diagram illustrating an example of frequency components of the in-cylinder pressure (p).
  • FIG. 8 shows the result of FFT (Fast Fourier transform) processing of the waveform of the in-cylinder pressure (p) shown in FIG.
  • the horizontal axis of the graph shown in FIG. 8 represents the order, and the vertical axis represents the Fourier coefficient (amplitude).
  • the solid line is the FFT-processed waveform of the actually measured value
  • the dashed line is the FFT-processed waveform of the calculated value using the above equation (5).
  • each band including each local maximum is defined as a low frequency band A, an intermediate frequency band B, and a high frequency band C in descending order.
  • the dashed line in the low frequency band A approximately coincides with the solid line in the low frequency band A. Since the solid line is only the in-cylinder pressure component, the dashed line in this frequency band (low frequency band A) is considered to be the in-cylinder pressure component.
  • the dashed line deviates from the solid line.
  • Reasons for this divergence include the gradual fluctuation of the secondary current (I 2 ) and the secondary voltage (V 2 ) due to the extension of the discharge path, and the secondary current (I 2 ) and the secondary voltage (V 2 ) due to re-discharge. ) is a sharp change. That is, it is considered that the dashed line in the intermediate frequency band B contains the frequency component of discharge path extension, and the dashed line in the high frequency band C contains the frequency component of re-discharge.
  • the middle frequency band B and the high frequency band C are removed from the waveforms of the secondary current (I 2 ) and the secondary voltage (V 2 ), and then the above equation (5 ) to calculate the in-cylinder pressure (p).
  • the in-cylinder pressure (p) is calculated value (in-cylinder pressure (p)) that eliminates the influence of the frequency components of discharge path extension and re-discharge.
  • FIG. 9 is a flow chart showing the procedure of in-cylinder pressure detection processing according to the present embodiment.
  • the overall control unit 81 detects secondary current (I 2 ) and secondary voltage (V 2 ) (S1). In the processing of S1, the discharge waveform (discharge period waveform) of the secondary current (I 2 ) and the secondary voltage (V 2 ) is detected.
  • the general control unit 81 removes the high frequency component from the discharge waveform and obtains the values of the secondary current (I 2 ) and the secondary voltage (V 2 ) from the removed waveform (S2).
  • FFT processing is performed so that a predetermined cutoff order or more (order range) is zero, and then inverse FFT processing is performed to remove high frequency components.
  • the cutoff order is determined based on the frequency component in the waveform of the in-cylinder pressure obtained using the combustion pressure sensor (the reference sensor prepared for obtaining the actual measurement value).
  • the overall control unit 81 calculates the in-cylinder pressure (p) using the above-described equation (5) obtained by converting the KIM relational expression (S3).
  • the general control unit 81 ends the in-cylinder pressure detection process.
  • FIG. 10 is a diagram showing an example of evaluating the detection accuracy of the in-cylinder pressure (p) according to this embodiment.
  • the horizontal axis of each graph shown in FIG. 10 represents time [msec] after the start of discharge.
  • the vertical axis of each graph shown in FIG. 7 represents secondary current (I 2 ) [A], secondary voltage (V 2 ) [kV], and in-cylinder pressure (p) [kPa].
  • the solid lines representing the secondary current (I 2 ) and secondary voltage (V 2 ) are obtained by removing the high frequency components by performing the above-described FFT processing and inverse FFT processing.
  • the solid line indicating the in-cylinder pressure (p) is the measured value of the in-cylinder pressure (p) measured using the combustion pressure sensor.
  • a dashed line indicating the in-cylinder pressure (p) is a calculated value calculated using the above equation (5). Specifically, the length (l) of the discharge path is the distance between the electrodes, and the result of substituting the secondary current (I 2 ) and the secondary voltage (V 2 ) from which high frequency components are removed into the relational expression is shown by the dashed line. is the in-cylinder pressure (p) indicated by .
  • the dashed line which is the calculated value calculated using the above formula (5), has a small divergence from the solid line, which is the actually measured value using the combustion pressure sensor. As a result, it can be confirmed that the detection accuracy (calculation accuracy) of the in-cylinder pressure (p) is improved. As a result, combustion control for each cylinder can be performed with high accuracy, and fuel efficiency of the vehicle can be improved.
  • the in-cylinder pressure detection method detects the in-cylinder pressure (p) using information on the secondary coil (secondary coil 320).
  • this in-cylinder pressure detection method high-frequency components are removed from the discharge waveform of the secondary coil, and information on the secondary current (I 2 ) and secondary voltage (V 2 ) is obtained from the discharge waveform from which the high-frequency components have been removed. .
  • the in-cylinder pressure (p) is calculated from the above equations (1) (equation (5)).
  • the space between the electrodes (between the center electrode 210 and the outer electrode 220) of the spark plug (spark plug 200) is placed in a virtual windless state, and the effects of discharge path elongation and re-discharge are eliminated, and the cylinder pressure (p ) can be detected.
  • the in-cylinder pressure (p) can be detected with high accuracy, and combustion control can be achieved in accordance with the characteristics of the parts of the cylinder. Therefore, it is possible to improve fuel efficiency.
  • it is not necessary to detect the in-cylinder pressure (p) using a combustion pressure sensor it is possible to reduce the number of parts and reduce the cost of the internal combustion engine system.
  • the length (l) of the discharge path in equation (1) is the shortest distance between the electrodes in the spark plug (spark plug 200). Therefore, the inter-electrode distance with high reproducibility can be used as the length of the discharge path. Also, detection of the length of the discharge path can be made unnecessary.
  • the removal of high-frequency components is performed by performing FFT processing so that a predetermined order range of the waveform data of the secondary current and secondary voltage is zero, and then performing reverse processing. It is achieved by performing FFT processing. As a result, high frequency components can be removed, and response delay and phase shift can be reduced.
  • the predetermined order range is determined from the frequency components in the pressure waveform of the measured values obtained using the combustion pressure sensor.
  • the internal combustion engine control device includes a primary coil (primary coil 310) and a secondary coil that generates an electromotive force when energization of the primary coil is interrupted. It has a side coil and a spark plug (spark plug 200) connected to the secondary coil. Then, the high frequency component is removed from the discharge waveform of the secondary coil, the information of the secondary current and the secondary voltage is obtained from the discharge waveform from which the high frequency component is removed, and from the above equations (1) (equation (5))
  • a control unit general control unit 81 that calculates the in-cylinder pressure is provided. As a result, the in-cylinder pressure (p) can be detected without the effects of discharge path extension and re-discharge.
  • the in-cylinder pressure (p) can be detected with high accuracy, and combustion control can be achieved in accordance with the characteristics of the parts of the cylinder. Therefore, it is possible to improve fuel efficiency. Moreover, since it is not necessary to detect the in-cylinder pressure (p) using a combustion pressure sensor, it is possible to reduce the number of parts and reduce the cost of the internal combustion engine system.
  • the in-cylinder pressure detection method and the internal combustion engine control device can also be applied to an internal combustion engine equipped with an in-cylinder pressure sensor (combustion pressure sensor).
  • in-cylinder pressure sensor combustion pressure sensor
  • the in-cylinder pressure sensor fails, the in-cylinder pressure is detected using the in-cylinder pressure detection method according to the present invention, and the internal combustion engine is controlled to realize fail-operational control.
  • the in-cylinder pressure detection method, the in-cylinder pressure sensor diagnostic method, and the internal combustion engine control device of the present invention have been described above, including their effects.
  • the in-cylinder pressure detection method, the in-cylinder pressure sensor diagnosis method, and the internal combustion engine control device of the present invention are not limited to the above-described embodiments, and are within the scope of the invention described in the claims.
  • Various alternative implementations are possible.
  • the overall control unit 81 is configured to perform the in-cylinder pressure detection process.
  • the in-cylinder pressure detection process according to the present invention may be performed by a control unit provided separately from the control device 1, such as a digital signal processor (DNP). In this case, it is possible to prevent the noise of the secondary coil from entering the control device 1 .
  • DNP digital signal processor
  • the control unit and the control device 1 constitute an internal combustion engine control device.
  • control device 10... analog input unit, 20... digital input unit, 30... A/D conversion unit, 40... RAM, 50... MPU, 60... ROM, 70... I/O port, 80... output circuit, 81 ... general control section, 82 ... fuel injection control section, 83 ... ignition control section, 84 ... cylinder determination section, 85 ... angle information generation section, 86 ... rotation speed information generation section, 87 ... intake air amount measurement section, 88 ...

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Abstract

The present invention accurately detects an in-cylinder pressure (p) irrespective of the influence of the extension of a discharge path. In a method for detecting an in-cylinder pressure according to the present invention, a high-frequency component is removed from a discharge waveform of a secondary-side coil, and information of a secondary current (I2) and a secondary voltage (V2) is acquired from the discharge waveform having the high-frequency component removed therefrom. Then, the in-cylinder pressure (p) is calculated from the KIM's relational expression.

Description

筒内圧力検出方法、筒内圧センサ診断方法及び内燃機関制御装置Cylinder Pressure Detection Method, Cylinder Pressure Sensor Diagnosis Method, and Internal Combustion Engine Control Device
　本発明は、筒内圧力検出方法、筒内圧センサ診断方法及び内燃機関制御装置に関する。 The present invention relates to an in-cylinder pressure detection method, an in-cylinder pressure sensor diagnosis method, and an internal combustion engine control device.
　近年、車両の燃費向上のため、理論空燃比よりも薄い混合気を燃焼して内燃機関を運転する技術や、燃焼後の排気ガスの一部を取り入れて再度吸気させる技術などを導入した内燃機関の制御装置が開発されている。 In recent years, in order to improve the fuel efficiency of vehicles, internal combustion engines that have introduced technology that burns a mixture that is leaner than the stoichiometric air-fuel ratio to operate the internal combustion engine, and technology that takes in part of the exhaust gas after combustion and re-breathes it. has been developed.
　この種の内燃機関の制御装置では、燃焼室における燃料や空気の量が理論値から乖離するため、点火プラグによる燃料への着火遅れが生じやすくなる。この着火遅れの期間や頻度は、部品ばらつきや運転条件の変化に応じて異なる。複数の気筒により構成される内燃機関において、全ての気筒で着火遅れを抑制するには、着火遅れの頻度が高い気筒に合わせて、燃料を増量するか、排気ガスの再循環量を減らす必要がある。 In this type of internal combustion engine control device, the amount of fuel and air in the combustion chamber deviates from the theoretical value, so ignition delay of the fuel by the spark plug tends to occur. The period and frequency of this ignition delay differ according to variations in parts and changes in operating conditions. In an internal combustion engine consisting of multiple cylinders, in order to suppress ignition delay in all cylinders, it is necessary to increase the amount of fuel or reduce the amount of recirculation of exhaust gas according to the cylinder with high ignition delay frequency. be.
　しかし、燃料を増量したり、排気ガスの再循環量を減らしたりすることは、燃費向上の抑制となる。そのため、気筒ごとの部品特性に合わせた、気筒別の燃焼制御が求められる。燃料噴射装置や点火コイルの気筒別の制御を行うには、気筒別の筒内圧力から着火遅れを検出する必要がある。したがって、気筒別の筒内圧力を精度良く検知する必要がある。 However, increasing the amount of fuel and reducing the amount of exhaust gas recirculation will suppress the improvement of fuel efficiency. Therefore, combustion control for each cylinder is required in accordance with the component characteristics of each cylinder. In order to control the fuel injection device and the ignition coil for each cylinder, it is necessary to detect the ignition delay from the in-cylinder pressure for each cylinder. Therefore, it is necessary to accurately detect the in-cylinder pressure for each cylinder.
　特許文献１には、点火放電と筒内圧力（ｐ）の関係式が開示されている。この関係式によると、放電電圧（Ｖ）と、放電電流（Ｉ）と、放電路長さ（ｌ）により、筒内圧力（ｐ）を算出可能である。 Patent Document 1 discloses a relational expression between ignition discharge and in-cylinder pressure (p). According to this relational expression, the in-cylinder pressure (p) can be calculated from the discharge voltage (V), the discharge current (I), and the discharge path length (l).
特開２０１８－１３５７８６号公報JP 2018-135786 A
　しかし、特許文献１に開示されている関係式では、放電路長さ（ｌ）を計測する必要がある。放電路は、点火プラグ電極間におけるガスの流れの影響を受けて伸長する。そして、放電路長さの計測には、燃焼室内の可視化が必要なため、現実的には困難である。さらに、筒内のガス流動は、燃焼サイクルによるばらつきが大きいため、点火プラグ電極間におけるガスの流れの推定は困難である。このため、特許文献１に開示された関係式では、気筒別の筒内圧力（ｐ）を精度良く検知することができない、という問題がある。 However, in the relational expression disclosed in Patent Document 1, it is necessary to measure the discharge path length (l). The discharge path extends under the influence of gas flow between the spark plug electrodes. In addition, since the measurement of the discharge path length requires visualization of the inside of the combustion chamber, it is practically difficult. Furthermore, since the gas flow in the cylinder varies greatly depending on the combustion cycle, it is difficult to estimate the gas flow between the spark plug electrodes. Therefore, the relational expression disclosed in Patent Document 1 has a problem that the in-cylinder pressure (p) for each cylinder cannot be detected with high accuracy.
　本発明の目的は、上記の問題点を考慮し、放電路伸長の影響を受けずに、筒内圧力（ｐ）を精度良く検知することにある。 An object of the present invention is to accurately detect the in-cylinder pressure (p) without being affected by the extension of the discharge path in consideration of the above problems.
　上記課題を解決し、本発明の目的を達成するため、本発明の筒内圧力検出方法は、１次側コイルと、１次側コイルの通電が遮断されると、起電力が生じる２次側コイルと、２次側コイルに接続された点火プラグとを有する内燃機関における２次側コイルの情報を用いて筒内圧力を検出する。この筒内圧力検出方法は、２次側コイルの放電波形から高周波成分を除去し、高周波成分を除去した放電波形から２次電流及び２次電圧の情報を取得し、以下の式（１）から筒内圧力を算出する。
Figure JPOXMLDOC01-appb-M000003
 　ただし、Ｖ２は２次電圧、Ｉ２は２次電流、ｐは筒内圧力、ｐ０は大気圧、ｌは放電路の長さである。 In order to solve the above problems and achieve the object of the present invention, the in-cylinder pressure detection method of the present invention includes a primary side coil and a secondary side coil in which an electromotive force is generated when energization of the primary side coil is interrupted. In-cylinder pressure is detected using information of a secondary side coil in an internal combustion engine having a coil and an ignition plug connected to the secondary side coil. This in-cylinder pressure detection method removes high-frequency components from the discharge waveform of the secondary coil, acquires information on the secondary current and secondary voltage from the discharge waveform from which the high-frequency components have been removed, and obtains information on the secondary current and secondary voltage from the following equation (1). Calculate the in-cylinder pressure.
Figure JPOXMLDOC01-appb-M000003
 where V2 is the secondary voltage, I2 is the secondary current, p is the cylinder pressure, p0 is the atmospheric pressure, and l is the length of the discharge path.
　上記構成の筒内圧力検出方法によれば、放電路伸長の影響されずに筒内圧力（ｐ）を精度良く検知することができる。
　なお、上述した以外の課題、構成および効果は、以下の実施形態の説明により明らかにされる。 According to the in-cylinder pressure detection method configured as described above, the in-cylinder pressure (p) can be accurately detected without being affected by the expansion of the discharge path.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.
本発明の一実施形態に係る内燃機関の基本構成例を示す全体構成図である。1 is an overall configuration diagram showing a basic configuration example of an internal combustion engine according to an embodiment of the present invention; FIG. 本発明の一実施形態に係る点火プラグを説明する部分拡大図である。1 is a partially enlarged view illustrating a spark plug according to an embodiment of the invention; FIG. 本発明の一実施形態に係る内燃機関の制御装置の機能構成を説明する機能ブロック図である。1 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to an embodiment of the present invention; FIG. 本発明の一実施形態に係る内燃機関の運転状態と点火プラグ周囲のガス流速との関係を説明する図である。FIG. 4 is a diagram for explaining the relationship between the operating state of the internal combustion engine and the gas flow velocity around the spark plug according to one embodiment of the present invention; Ａ，Ｂ　本発明の一実施形態に係る点火プラグの電極間における放電路と流速の関係を説明する図である。4A and 4B are diagrams for explaining the relationship between the discharge path and the flow velocity between the electrodes of the spark plug according to one embodiment of the present invention; 本発明の一実施形態に係る点火コイルを含む電気回路を説明する図である。It is a figure explaining an electric circuit containing an ignition coil concerning one embodiment of the present invention. 関係式のみを用いて算出した筒内圧力（ｐ）の精度を評価した例を示す図である。FIG. 4 is a diagram showing an example of evaluation of accuracy of in-cylinder pressure (p) calculated using only a relational expression; 筒内圧力の周波数成分の例について説明する図である。FIG. 4 is a diagram illustrating an example of frequency components of in-cylinder pressure; 本発明の一実施形態に係る筒内圧力検出処理の手順を示すフローチャートである。4 is a flowchart showing the procedure of in-cylinder pressure detection processing according to the embodiment of the present invention; 本発明の一実施形態に係る筒内圧力（ｐ）の検出精度を評価した例を示す図である。FIG. 4 is a diagram showing an example of evaluation of detection accuracy of in-cylinder pressure (p) according to one embodiment of the present invention.
１．実施形態
　以下、本発明の一実施形態に係る内燃機関制御装置について説明する。なお、各図において共通の部材には、同一の符号を付している。 1. Embodiment Hereinafter, an internal combustion engine control device according to an embodiment of the present invention will be described. In addition, the same code|symbol is attached|subjected to the member which is common in each figure.
［内燃機関システム］
　まず、本実施形態による内燃機関システムの構成について説明する。図１は、本発明の一実施形態に係る内燃機関の基本構成例を示す全体構成図である。 [Internal combustion engine system]
First, the configuration of the internal combustion engine system according to this embodiment will be described. FIG. 1 is an overall configuration diagram showing a basic configuration example of an internal combustion engine according to an embodiment of the present invention.
　図１に示す内燃機関１００は、単気筒でも複数気筒を有するものでもよいが、実施形態では、４気筒を有する内燃機関１００を例示して説明する。図１に示すように、内燃機関１００では、外部から吸引した空気はエアクリーナ１１０、吸気管１１１、吸気マニホールド１１２を通流する。吸気マニホールド１１２を通った空気は、吸気弁１５１が開いたときに各気筒１５０に流入する。各気筒１５０に流入する空気量は、スロットル弁１１３により調整される。スロットル弁１１３で調整された空気量は、流量センサ１１４により測定される。 The internal combustion engine 100 shown in FIG. 1 may have a single cylinder or multiple cylinders, but in the embodiment, the internal combustion engine 100 having four cylinders will be described as an example. As shown in FIG. 1 , in internal combustion engine 100 , air sucked from the outside flows through air cleaner 110 , intake pipe 111 , and intake manifold 112 . Air passing through the intake manifold 112 flows into each cylinder 150 when the intake valve 151 is opened. The amount of air flowing into each cylinder 150 is adjusted by the throttle valve 113 . The amount of air adjusted by throttle valve 113 is measured by flow rate sensor 114 .
　スロットル弁１１３には、スロットルの開度を検出するスロットル開度センサ１１３ａが設けられている。スロットル開度センサ１１３ａで検出されたスロットル弁１１３の開度情報は、制御装置（Electronic Control Unit：ＥＣＵ）１に出力される。 The throttle valve 113 is provided with a throttle opening sensor 113a that detects the opening of the throttle. The opening degree information of the throttle valve 113 detected by the throttle opening degree sensor 113 a is output to a control device (Electronic Control Unit: ECU) 1 .
　本実施形態では、スロットル弁１１３として、電動機で駆動される電子スロットル弁を適用する。しかし、本発明に係るスロットル弁としては、空気の流量を適切に調整できるものであれば、その他の方式によるものを適用してもよい。 In this embodiment, an electronic throttle valve driven by an electric motor is applied as the throttle valve 113 . However, as the throttle valve according to the present invention, any other method may be applied as long as it can appropriately adjust the air flow rate.
　各気筒１５０に流入したガスの温度は、吸気温センサ１１５で検出される。 The temperature of the gas that has flowed into each cylinder 150 is detected by the intake air temperature sensor 115 .
　クランクシャフト１２３に取り付けられたリングギア１２０の径方向外側には、クランク角センサ１２１が設けられている。クランク角センサ１２１は、クランクシャフト１２３の回転角度を検出する。本実施形態では、クランク角センサ１２１は、１０°毎及び燃焼周期毎のクランクシャフト１２３の回転角度を検出する。 A crank angle sensor 121 is provided radially outside the ring gear 120 attached to the crankshaft 123 . Crank angle sensor 121 detects the rotation angle of crankshaft 123 . In this embodiment, the crank angle sensor 121 detects the rotation angle of the crankshaft 123 every 10 degrees and every combustion cycle.
　シリンダヘッドのウォータジャケット（図示せず）には、水温センサ１２２が設けられている。水温センサ１２２は、内燃機関１００の冷却水の温度を検出する。 A water temperature sensor 122 is provided in the water jacket (not shown) of the cylinder head. A water temperature sensor 122 detects the temperature of the cooling water of the internal combustion engine 100 .
　また、車両には、アクセルペダル１２５の変位量（踏み込み量）を検出するアクセルポジションセンサ（Accelerator Position Sensor：ＡＰＳ）１２６が設けられている。アクセルポジションセンサ１２６は、運転者の要求トルクを検出する。アクセルポジションセンサ１２６で検出された運転者の要求トルクは、後述する制御装置１に出力される。制御装置１は、この要求トルクに基づいて、スロットル弁１１３を制御する。 The vehicle is also provided with an accelerator position sensor (APS) 126 that detects the amount of displacement (depression amount) of the accelerator pedal 125 . An accelerator position sensor 126 detects the torque requested by the driver. The driver's requested torque detected by the accelerator position sensor 126 is output to the control device 1, which will be described later. The control device 1 controls the throttle valve 113 based on this required torque.
　燃料タンク１３０に貯留された燃料は、燃料ポンプ１３１によって吸引及び加圧される。燃料ポンプ１３１によって吸引及び加圧された燃料は、燃料配管１３３に設けられたプレッシャレギュレータ１３２で所定の圧力に調整される。そして、所定の圧力に調整された燃料は、燃料噴射装置（インジェクタ）１３４から各気筒１５０内に噴射される。プレッシャレギュレータ１３２で圧力調整された後の余分な燃料は、戻り配管（図示せず）を介して燃料タンク１３０に戻される。 The fuel stored in the fuel tank 130 is sucked and pressurized by the fuel pump 131 . Fuel sucked and pressurized by the fuel pump 131 is adjusted to a predetermined pressure by a pressure regulator 132 provided in the fuel pipe 133 . Fuel adjusted to a predetermined pressure is injected into each cylinder 150 from a fuel injection device (injector) 134 . Excess fuel after pressure regulation by the pressure regulator 132 is returned to the fuel tank 130 via a return pipe (not shown).
　燃料噴射装置１３４の制御は、後述する制御装置１の燃料噴射制御部８２の燃料噴射パルス（制御信号）に基づいて行われる。 The control of the fuel injection device 134 is performed based on the fuel injection pulse (control signal) of the fuel injection control section 82 of the control device 1, which will be described later.
　各気筒１５０には、排気弁１５２と、排気マニホールド１６０が取り付けられている。排気弁１５２が開くと、気筒１５０から排気マニホールド１６０に排気ガスが排出される。排気マニホールド１６０は、燃焼後のガス（排気ガス）を、気筒１５０の外側に排出する。排気マニホールド１６０の排気側には、三元触媒１６１が設けられている。三元触媒１６１は、排気ガスを浄化する。三元触媒１６１により浄化された排気ガスは、大気に排出される。 An exhaust valve 152 and an exhaust manifold 160 are attached to each cylinder 150 . When exhaust valve 152 is opened, exhaust gas is discharged from cylinder 150 to exhaust manifold 160 . The exhaust manifold 160 discharges gas (exhaust gas) after combustion to the outside of the cylinder 150 . A three-way catalyst 161 is provided on the exhaust side of the exhaust manifold 160 . The three-way catalyst 161 purifies exhaust gas. The exhaust gas purified by the three-way catalyst 161 is discharged into the atmosphere.
　三元触媒１６１の上流側には、上流側空燃比センサ１６２が設けられている。上流側空燃比センサ１６２は、各気筒１５０から排出された排気ガスの空燃比を連続的に検出する。 An upstream air-fuel ratio sensor 162 is provided upstream of the three-way catalyst 161 . The upstream air-fuel ratio sensor 162 continuously detects the air-fuel ratio of exhaust gas discharged from each cylinder 150 .
　また、三元触媒１６１の下流側には、下流側空燃比センサ１６３が設けられている。下流側空燃比センサ１６３は、理論空燃比近傍でスイッチ的な検出信号を出力する。本実施形態の下流側空燃比センサ１６３は、Ｏ２センサである。 A downstream side air-fuel ratio sensor 163 is provided downstream of the three-way catalyst 161 . The downstream air-fuel ratio sensor 163 outputs a switch-like detection signal near the stoichiometric air-fuel ratio. The downstream air-fuel ratio sensor 163 of this embodiment is an O2 sensor.
　各気筒１５０の上部には、点火プラグ２００が各々設けられている。点火プラグ２００は、放電（点火）により火花を発生させ、その火花が、気筒１５０内の空気と燃料との混合気に着火する。これにより、気筒１５０内で爆発が起こり、ピストン１７０が押し下げられる。ピストン１７０が押し下げられることにより、クランクシャフト１２３が回転する。点火プラグ２００には、点火プラグ２００に供給される電気エネルギー（電圧）を生成する点火コイル３００が接続されている。 A spark plug 200 is provided at the top of each cylinder 150 . The spark plug 200 generates a spark by electric discharge (ignition), and the spark ignites the air-fuel mixture in the cylinder 150 . This causes an explosion in cylinder 150 and pushes down piston 170 . As the piston 170 is pushed down, the crankshaft 123 rotates. An ignition coil 300 that generates electrical energy (voltage) to be supplied to the ignition plug 200 is connected to the ignition plug 200 .
　前述したスロットル開度センサ１１３ａ、流量センサ１１４、クランク角センサ１２１、アクセルポジションセンサ１２６、水温センサ１２２等の各種センサからの出力信号は、制御装置１に出力される。制御装置１は、これら各種センサからの出力信号に基づいて、内燃機関１００の運転状態を検出する。そして、制御装置１は、気筒１５０内に送出する空気量、燃料噴射装置１３４からの燃料噴射量、点火プラグ２００の点火タイミング等の制御を行う。 Output signals from various sensors such as the throttle opening sensor 113a, the flow rate sensor 114, the crank angle sensor 121, the accelerator position sensor 126, the water temperature sensor 122, etc. are output to the control device 1. The control device 1 detects the operating state of the internal combustion engine 100 based on output signals from these various sensors. The control device 1 controls the amount of air sent into the cylinder 150, the amount of fuel injected from the fuel injection device 134, the ignition timing of the spark plug 200, and the like.
［点火プラグ］
　次に、点火プラグ２００について、図２を参照して説明する。
　図２は、点火プラグ２００を説明する部分拡大図である。 [Spark plug]
Next, spark plug 200 will be described with reference to FIG.
FIG. 2 is a partially enlarged view for explaining spark plug 200. As shown in FIG.
　図２に示すように、点火プラグ２００は、中心電極２１０と、外側電極２２０とを有している。中心電極２１０は、絶縁体２３０を介してプラグベース（不図示）に支持されている。これにより、中心電極２１０は、絶縁されている。外側電極２２０は接地されている。 As shown in FIG. 2, the spark plug 200 has a center electrode 210 and an outer electrode 220. As shown in FIG. Center electrode 210 is supported by a plug base (not shown) via insulator 230 . Thereby, the center electrode 210 is insulated. Outer electrode 220 is grounded.
　点火コイル３００（図１参照）において電圧が発生すると、中心電極２１０に所定の電圧（本実施形態では、例えば２０，０００Ｖ～４０，０００Ｖ）が印加される。中心電極２１０に所定の電圧が印加されると、中心電極２１０と外側電極２２０との間で放電（点火）が生じる。そして、放電により発生した火花が、気筒１５０内の空気と燃料との混合気に着火する。 When a voltage is generated in the ignition coil 300 (see FIG. 1), a predetermined voltage (eg, 20,000 V to 40,000 V in this embodiment) is applied to the center electrode 210 . When a predetermined voltage is applied to center electrode 210 , discharge (ignition) occurs between center electrode 210 and outer electrode 220 . A spark generated by the discharge ignites the air-fuel mixture in the cylinder 150 .
　なお、気筒１５０内におけるガス成分の絶縁破壊を起こして放電（点火）が発生する電圧は、中心電極２１０と外側電極２２０との間に存在する気体（ガス）の状態や気筒１５０の筒内圧に応じて変動する。この放電が発生する電圧を絶縁破壊電圧と言う。 It should be noted that the voltage at which electrical discharge (ignition) occurs due to dielectric breakdown of the gas components in the cylinder 150 depends on the state of the gas existing between the center electrode 210 and the outer electrode 220 and the internal pressure of the cylinder 150. Varies accordingly. The voltage at which this discharge occurs is called dielectric breakdown voltage.
　点火プラグ２００の放電制御（点火制御）は、後述する制御装置１の点火制御部８３により行われる。 The discharge control (ignition control) of the spark plug 200 is performed by an ignition control section 83 of the control device 1, which will be described later.
［制御装置のハードウェア構成］
　次に、制御装置１のハードウェアの全体構成を説明する。 [Hardware configuration of control device]
Next, the overall hardware configuration of the control device 1 will be described.
　図１に示すように、制御装置１は、アナログ入力部１０と、デジタル入力部２０と、Ａ／Ｄ（Ａｎａｌｏｇ／Ｄｉｇｉｔａ）変換部３０と、ＲＡＭ（Random Access Memory）４０と、ＭＰＵ（Micro-Processing Unit）５０と、ＲＯＭ（Read Only Memory）６０と、Ｉ／Ｏ（Input/Output）ポート７０と、出力回路８０と、を有する。 As shown in FIG. 1, the control device 1 includes an analog input section 10, a digital input section 20, an A/D (Analog/Digital) conversion section 30, a RAM (Random Access Memory) 40, and an MPU (Micro- Processing Unit) 50 , ROM (Read Only Memory) 60 , I/O (Input/Output) port 70 , and output circuit 80 .
　アナログ入力部１０には、スロットル開度センサ１１３ａ、流量センサ１１４、アクセルポジションセンサ１２６、上流側空燃比センサ１６２、下流側空燃比センサ１６３、水温センサ１２２等の各種センサからのアナログ出力信号が入力される。 Analog output signals from various sensors such as the throttle opening sensor 113a, the flow rate sensor 114, the accelerator position sensor 126, the upstream side air-fuel ratio sensor 162, the downstream side air-fuel ratio sensor 163, the water temperature sensor 122, etc. are input to the analog input unit 10. be done.
　アナログ入力部１０には、Ａ／Ｄ変換部３０が接続されている。アナログ入力部１０に入力された各種センサからのアナログ出力信号は、ノイズ除去等の信号処理が行われた後、Ａ／Ｄ変換部３０でデジタル信号に変換される。そして、Ａ／Ｄ変換部３０により変換されたデジタル信号は、ＲＡＭ４０に記憶される。 An A/D conversion section 30 is connected to the analog input section 10 . Analog output signals from various sensors input to the analog input unit 10 are subjected to signal processing such as noise removal, and then converted to digital signals by the A/D conversion unit 30 . The digital signal converted by the A/D converter 30 is stored in the RAM 40 .
　デジタル入力部２０には、クランク角センサ１２１からのデジタル出力信号が入力される。 A digital output signal from the crank angle sensor 121 is input to the digital input unit 20 .
　デジタル入力部２０には、Ｉ／Ｏポート７０が接続されている。デジタル入力部２０に入力されたデジタル出力信号は、Ｉ／Ｏポート７０を介してＲＡＭ４０に記憶される。 An I/O port 70 is connected to the digital input section 20 . A digital output signal input to the digital input section 20 is stored in the RAM 40 via the I/O port 70 .
　ＲＡＭ４０に記憶された各出力信号は、ＭＰＵ５０で演算処理される。 Each output signal stored in the RAM 40 is arithmetically processed by the MPU 50.
　ＭＰＵ５０は、ＲＯＭ６０に記憶された制御プログラム（図示せず）を実行することで、ＲＡＭ４０に記憶された出力信号を、制御プログラムに従って演算処理する。ＭＰＵ５０は、制御プログラムに従って、内燃機関１００を駆動する各アクチュエータ（例えば、スロットル弁１１３、プレッシャレギュレータ１３２、点火プラグ２００等）の作動量を規定する制御値を算出し、その制御値をＲＡＭ４０に一時的に記憶する。 By executing a control program (not shown) stored in the ROM 60, the MPU 50 arithmetically processes the output signals stored in the RAM 40 according to the control program. The MPU 50 calculates a control value that defines the actuation amount of each actuator (for example, the throttle valve 113, the pressure regulator 132, the spark plug 200, etc.) that drives the internal combustion engine 100 according to the control program, and temporarily stores the control value in the RAM 40. memorize.
　ＲＡＭ４０に記憶されたアクチュエータの作動量を規定する制御値は、Ｉ／Ｏポート７０を介して出力回路８０に出力される。 A control value that defines the actuation amount of the actuator stored in the RAM 40 is output to the output circuit 80 via the I/O port 70 .
　出力回路８０には、各種センサ（例えば、アクセルポジションセンサ１２６）からの出力信号に基づいて内燃機関の全体制御を行う全体制御部８１（図３参照）と、燃料噴射装置１３４のプランジャロッド（不図示）の駆動を制御する燃料噴射制御部８２（図３参照）と、点火プラグ２００に印加する電圧を制御する点火制御部８３（図３参照）の機能などが設けられている。 The output circuit 80 includes an overall control section 81 (see FIG. 3) that performs overall control of the internal combustion engine based on output signals from various sensors (for example, the accelerator position sensor 126), and a plunger rod (non-reactive) of the fuel injector 134. 3) for controlling the driving of the fuel injection control unit 82 (see FIG. 3) and an ignition control unit 83 (see FIG. 3) for controlling the voltage applied to the spark plug 200.
［制御装置の機能ブロック］
　次に、制御装置１の機能構成を、図３を参照して説明する。 [Functional block of control device]
Next, the functional configuration of the control device 1 will be described with reference to FIG.
　図３は、制御装置１の機能構成を説明する機能ブロック図である。 FIG. 3 is a functional block diagram illustrating the functional configuration of the control device 1. FIG.
　制御装置１の各機能は、ＭＰＵ５０がＲＯＭ６０記憶された制御プログラムを実行することにより、出力回路８０における各種機能として実現される。出力回路８０における各種機能は、例えば、燃料噴射制御部８２による燃料噴射装置１３４の制御や、点火制御部８３による点火プラグ２００の放電制御がある。 Each function of the control device 1 is realized as various functions in the output circuit 80 by the MPU 50 executing the control program stored in the ROM 60. Various functions of the output circuit 80 include, for example, control of the fuel injection device 134 by the fuel injection control section 82 and discharge control of the spark plug 200 by the ignition control section 83 .
　図３に示すように、制御装置１の出力回路８０は、全体制御部８１と、燃料噴射制御部８２と、点火制御部８３とを有する。 As shown in FIG. 3, the output circuit 80 of the control device 1 has a general control section 81, a fuel injection control section 82, and an ignition control section 83.
［全体制御部］
　全体制御部８１は、アクセルポジションセンサ１２６に接続されており、アクセルポジションセンサ１２６からの要求トルク（加速信号Ｓ１）を受け付ける。全体制御部８１は、後述する筒内圧力検出処理により筒内圧力（ｐ）を検出する。 [Overall control part]
The overall control unit 81 is connected to the accelerator position sensor 126 and receives the requested torque (acceleration signal S1) from the accelerator position sensor 126. FIG. The overall control unit 81 detects the in-cylinder pressure (p) through in-cylinder pressure detection processing, which will be described later.
　全体制御部８１は、アクセルポジションセンサ１２６からの要求トルク（加速信号Ｓ１）と、検出した筒内圧力（ｐ）とに基づいて、燃料噴射制御部８２と、点火制御部８３の全体的な制御を行う。 General control unit 81 controls overall fuel injection control unit 82 and ignition control unit 83 based on the required torque (acceleration signal S1) from accelerator position sensor 126 and the detected in-cylinder pressure (p). I do.
［燃料噴射制御部］
　燃料噴射制御部８２は、内燃機関１００の各気筒１５０を判別する気筒判別部８４と、クランクシャフト１２３のクランク角を計測する角度情報生成部８５と、エンジン回転数を計測する回転数情報生成部８６と、に接続されている。燃料噴射制御部８２は、気筒判別部８４からの気筒判別情報Ｓ３と、角度情報生成部８５からのクランク角度情報Ｓ４と、回転数情報生成部８６からのエンジン回転数情報Ｓ５と、を受け付ける。 [Fuel injection controller]
The fuel injection control unit 82 includes a cylinder discrimination unit 84 that discriminates each cylinder 150 of the internal combustion engine 100, an angle information generation unit 85 that measures the crank angle of the crankshaft 123, and a rotation speed information generation unit that measures the engine speed. 86 and . Fuel injection control unit 82 receives cylinder identification information S3 from cylinder identification unit 84, crank angle information S4 from angle information generation unit 85, and engine speed information S5 from rotation speed information generation unit 86.
　また、燃料噴射制御部８２は、気筒１５０内に吸気される空気の吸気量を計測する吸気量計測部８７と、エンジン負荷を計測する負荷情報生成部８８と、エンジン冷却水の温度を計測する水温計測部８９と、に接続されている。燃料噴射制御部８２は、吸気量計測部８７からの吸気量情報Ｓ６と、負荷情報生成部８８からのエンジン負荷情報Ｓ７と、水温計測部８９からの冷却水温度情報Ｓ８と、を受け付ける。 The fuel injection control unit 82 also includes an intake air amount measurement unit 87 that measures the amount of air taken into the cylinder 150, a load information generation unit 88 that measures the engine load, and a temperature of the engine cooling water. It is connected to the water temperature measurement part 89 and. The fuel injection control unit 82 receives intake air amount information S6 from the intake air amount measuring unit 87, engine load information S7 from the load information generating unit 88, and cooling water temperature information S8 from the water temperature measuring unit 89.
　燃料噴射制御部８２は、受け付けた各情報に基づいて、燃料噴射装置１３４から噴射される燃料の噴射量と噴射時間を算出する。そして、燃料噴射制御部８２は、算出した燃料の噴射量と噴射時間とに基づいて生成した燃料噴射パルスＳ９を燃料噴射装置１３４に送信する。 The fuel injection control unit 82 calculates the injection amount and the injection time of the fuel injected from the fuel injection device 134 based on the received information. Then, the fuel injection control unit 82 transmits a fuel injection pulse S9 generated based on the calculated fuel injection amount and injection time to the fuel injection device 134 .
［点火制御部］
　点火制御部８３は、全体制御部８１のほか、気筒判別部８４と、角度情報生成部８５と、回転数情報生成部８６と、負荷情報生成部８８と、水温計測部８９とに接続されており、これらからの各情報を受け付ける。 [Ignition control part]
The ignition control unit 83 is connected not only to the overall control unit 81 but also to a cylinder discrimination unit 84, an angle information generation unit 85, a rotation speed information generation unit 86, a load information generation unit 88, and a water temperature measurement unit 89. and accept each information from them.
　点火制御部８３は、受け付けた各情報に基づいて、点火コイル３００の１次側コイル３１０（図８参照）に通電する電流量（通電角）と、通電開始時間と、１次側コイル３１０に通電した電流を遮断する時間（点火時間）を算出する。 Based on the received information, the ignition control unit 83 controls the amount of current (energization angle) to be energized to the primary coil 310 (see FIG. 8) of the ignition coil 300, the energization start time, and the current to the primary coil 310. Calculate the time (ignition time) to cut off the applied current.
　点火制御部８３は、算出した通電量と、通電開始時間と、点火時間とに基づいて、点火コイル３００の１次側コイル３１０に通電信号ＳＡを出力することで、点火プラグ２００による放電制御（点火制御）を行う。 The ignition control unit 83 outputs an energization signal SA to the primary coil 310 of the ignition coil 300 based on the calculated energization amount, energization start time, and ignition time, thereby controlling discharge by the spark plug 200 ( ignition control).
［内燃機関の運転状態と点火プラグ周囲のガス流速との関係］
　次に、内燃機関１００の運転状態と点火プラグ２００周囲のガス流速との関係を、図４を参照して説明する。
　図４は、内燃機関１００の運転状態と点火プラグ２００周囲のガス流速との関係を説明する図である。 [Relationship between the operating state of the internal combustion engine and the gas flow velocity around the spark plug]
Next, the relationship between the operating state of the internal combustion engine 100 and the gas flow velocity around the spark plug 200 will be described with reference to FIG.
FIG. 4 is a diagram for explaining the relationship between the operating state of internal combustion engine 100 and the flow velocity of gas around spark plug 200. As shown in FIG.
　図４に示すように、一般的に、エンジン回転数や負荷が高いほど、気筒１５０内のガス流速が高くなり、点火プラグ２００周囲のガスが高流速になる。したがって、エンジン回転数や負荷が高い場合は、点火プラグ２００の中心電極２１０と外側電極２２０との間において、ガスが高速に流れることとなる。 As shown in FIG. 4, generally, the higher the engine speed and load, the higher the gas flow velocity in the cylinder 150 and the higher the flow velocity of the gas around the spark plug 200 . Therefore, when the engine speed or load is high, gas flows at high speed between the center electrode 210 and the outer electrode 220 of the spark plug 200 .
　また、排気再循環（ＥＧＲ：Exhaust Gas Recirculation）が行われる内燃機関１００では、エンジン回転数と負荷の関係に応じて、例えば図４に示すようにＥＧＲ率が設定される。なお、ＥＧＲ率をより高く設定する高ＥＧＲ領域を拡大するほど、低燃費化や低排気化を実現できる。しかし、高ＥＧＲ領域では、火炎核が成長する確率が下がるため、点火プラグ２００において着火不良が生じやすくなる。 Also, in the internal combustion engine 100 in which exhaust gas recirculation (EGR) is performed, the EGR rate is set, for example, as shown in FIG. 4 according to the relationship between the engine speed and the load. It should be noted that as the high EGR region in which the EGR rate is set higher is expanded, the fuel consumption and exhaust emissions can be reduced. However, in the high EGR region, the flame kernel is less likely to grow, and the spark plug 200 is more likely to cause poor ignition.
［点火プラグの電極間における放電路と流速の関係］
　次に、点火プラグの電極間における放電路と流速の関係を、図５Ａ，Ｂを参照して説明する。
　図５Ａ，Ｂは、点火プラグの電極間における放電路と流速の関係を説明する図である。 [Relationship between discharge path and flow velocity between spark plug electrodes]
Next, the relationship between the discharge path between the electrodes of the ignition plug and the flow velocity will be described with reference to FIGS. 5A and 5B.
5A and 5B are diagrams for explaining the relationship between the discharge path between the electrodes of the spark plug and the flow velocity.
　図５Ａ，Ｂに示すように、点火プラグ２００の中心電極２１０と外側電極２２０の間に絶縁破壊が生じると、電極２１０，２２０間に流れる電流が一定値以下になるまでの間、電極２１０，２２０間に放電路２１１が形成される。この放電路２１１に可燃ガスが接触すると、火炎核が成長して燃焼に至る。放電路２１１は、電極２１０，２２０間のガス流れの影響を受けて移動するため、図５Ａに示すように、ガス流速が高いほど短時間で長い放電路２１１を形成する。一方、図５Ｂに示すように、ガス流速が低いほど放電路２１１が短くなる。 As shown in FIGS. 5A and 5B, if a dielectric breakdown occurs between the center electrode 210 and the outer electrode 220 of the spark plug 200, the electrodes 210 and 220 will continue to operate until the current flowing between the electrodes 210 and 220 drops below a certain value. A discharge path 211 is formed between 220 . When combustible gas comes into contact with the discharge path 211, a flame kernel grows and burns. Since the discharge path 211 moves under the influence of the gas flow between the electrodes 210 and 220, as shown in FIG. 5A, the higher the gas flow rate, the longer the discharge path 211 is formed in a short time. On the other hand, as shown in FIG. 5B, the lower the gas flow rate, the shorter the discharge path 211 becomes.
　内燃機関１００が高ＥＧＲ率で運転される場合は、可燃ガスが放電路２１１と接触しても火炎核が成長する確率が下がる。そのため、可燃ガスが放電路２１１と接触する機会を増やす必要がある。前述したように、放電路２１１は、ガスの絶縁を破壊して生成される。したがって、放電路２１１の維持に必要な電流を一定とすれば、放電路２１１の維持には、放電路２１１の長さに応じた電力の供給が必要となる。 When the internal combustion engine 100 is operated at a high EGR rate, even if the combustible gas contacts the discharge path 211, the flame kernel is less likely to grow. Therefore, it is necessary to increase the chances of the combustible gas coming into contact with the discharge path 211 . As described above, the discharge path 211 is created by breaking the gas insulation. Therefore, if the current required to maintain the discharge path 211 is constant, it is necessary to supply power corresponding to the length of the discharge path 211 to maintain the discharge path 211 .
　ガス流速が高い場合は、短時間で大きな電力を点火コイル３００から点火プラグ２００へ出力するように点火コイル３００の通電制御を行う。これにより、図５Ａに示すような長い放電路２１１を形成することができる。その結果、放電路２１１は、広範な空間のガスとの接触機会を得ることが可能となる。 When the gas flow velocity is high, the energization control of the ignition coil 300 is performed so that a large amount of electric power is output from the ignition coil 300 to the spark plug 200 in a short period of time. Thereby, a long discharge path 211 as shown in FIG. 5A can be formed. As a result, the discharge path 211 can obtain contact opportunities with gas in a wide space.
　一方、ガス流速が低い場合は、点火コイル３００から点火プラグ２００へ小さな電力を長時間出力し続けるように点火コイル３００の通電制御を行う。これにより、図５Ｂに示すような短い放電路２１１の形成を維持することができる。その結果、放電路２１１は、点火プラグ２００の電極付近を通過するガスとの接触機会をより長時間にわたって得ることができる。 On the other hand, when the gas flow velocity is low, the energization control of the ignition coil 300 is performed so that the ignition coil 300 continues to output a small electric power to the ignition plug 200 for a long time. Thereby, formation of a short discharge path 211 as shown in FIG. 5B can be maintained. As a result, the discharge path 211 can obtain contact opportunities with the gas passing near the electrodes of the spark plug 200 for a longer period of time.
［点火コイルの電気回路］
　次に、一実施形態に係る点火コイルについて、図６を参照して説明する。
　図６は、一実施形態に係る点火コイルを含む電気回路を説明する図である。 [Electric circuit of ignition coil]
Next, an ignition coil according to one embodiment will be described with reference to FIG.
FIG. 6 is a diagram illustrating an electric circuit including an ignition coil according to one embodiment.
　図６に示す電気回路４００は、点火コイル３００を有している。点火コイル３００は、所定の巻き数で巻かれた１次側コイル３１０と、１次側コイル３１０よりも多い巻き数で巻かれた２次側コイル３２０と、を含んで構成される。 An electric circuit 400 shown in FIG. 6 has an ignition coil 300 . Ignition coil 300 includes a primary coil 310 wound with a predetermined number of turns and a secondary coil 320 wound with a larger number of turns than primary coil 310 .
　１次側コイル３１０の一端は、直流電源３３０に接続されている。これにより、１次側コイル３１０には、所定の電圧（例えば１２Ｖ）が印加される。１次側コイル３１０の他端は、イグナイタ（通電制御回路）３４０のコレクタ（Ｃ）端子に接続されており、イグナイタ３４０を介して接地されている。イグナイタ３４０には、トランジスタや電界効果トランジスタ（Field Effect Transistor：FET）などが用いられる。 One end of the primary coil 310 is connected to the DC power supply 330 . Thereby, a predetermined voltage (for example, 12 V) is applied to the primary coil 310 . The other end of the primary coil 310 is connected to a collector (C) terminal of an igniter (energization control circuit) 340 and grounded via the igniter 340 . A transistor, a field effect transistor (FET), or the like is used for the igniter 340 .
　イグナイタ３４０のベース（Ｂ）端子は、点火制御部８３に接続されている。点火制御部８３から出力された通電信号ＳＡは、イグナイタ３４０のベース（Ｂ）端子に入力される。イグナイタ３４０のベース（Ｂ）端子に通電信号ＳＡが入力されると、イグナイタ３４０のコレクタ（Ｃ）端子とエミッタ（Ｅ）端子間が通電状態となり、コレクタ（Ｃ）端子とエミッタ（Ｅ）端子間に電流が流れる。これにより、点火制御部８３からイグナイタ３４０を介して点火コイル３００の１次側コイル３１０に通電信号ＳＡが出力される。その結果、１次側コイル３１０に電流が流れて電力（電気エネルギー）が蓄積される。 A base (B) terminal of the igniter 340 is connected to the ignition control section 83 . The energization signal SA output from the ignition control unit 83 is input to the base (B) terminal of the igniter 340 . When the energization signal SA is input to the base (B) terminal of the igniter 340, the collector (C) terminal and the emitter (E) terminal of the igniter 340 become energized, and the collector (C) terminal and the emitter (E) terminal become energized. current flows through As a result, the energization signal SA is output from the ignition control unit 83 to the primary coil 310 of the ignition coil 300 via the igniter 340 . As a result, a current flows through the primary coil 310 and electric power (electrical energy) is accumulated.
　点火制御部８３からの通電信号ＳＡの出力が停止すると、１次側コイル３１０に流れる電流が遮断される。その結果、１次側コイル３１０に対するコイルの巻き数比に応じた高電圧が２次側コイル３２０に発生する。なお、点火プラグ２００と２次側コイル３２０との間には、２次電圧を検出する電圧検出部と、２次電流を検出する電流検出部が設けられている。 When the output of the energization signal SA from the ignition control unit 83 is stopped, the current flowing through the primary coil 310 is interrupted. As a result, a high voltage corresponding to the turns ratio of the coil to the primary coil 310 is generated in the secondary coil 320 . A voltage detection unit that detects secondary voltage and a current detection unit that detects secondary current are provided between spark plug 200 and secondary coil 320 .
　２次側コイル３２０に発生する高電圧は、点火プラグ２００の中心電極２１０（図５Ａ，Ｂ参照）に印加される。これにより、点火プラグ２００の中心電極２１０と、外側電極２２０との間に電位差が発生する。この中心電極２１０と外側電極２２０との間に発生した電位差が、ガス（気筒１５０内の混合気）の絶縁破壊電圧Ｖｍ以上になると、ガス成分が絶縁破壊されて中心電極２１０と外側電極２２０との間に放電が生じる。その結果、燃料（混合気）への点火（着火）が行われる。点火制御部８３は、通電信号ＳＡを用いて電気回路４００を上述しように動作させ、点火コイル３００の通電を制御する。 The high voltage generated in the secondary coil 320 is applied to the center electrode 210 of the spark plug 200 (see FIGS. 5A and 5B). Thereby, a potential difference is generated between the center electrode 210 and the outer electrode 220 of the spark plug 200 . When the potential difference generated between the center electrode 210 and the outer electrode 220 becomes equal to or higher than the dielectric breakdown voltage Vm of the gas (air mixture in the cylinder 150), the gas component breaks down and the center electrode 210 and the outer electrode 220 are separated. Discharge occurs during As a result, the fuel (air-fuel mixture) is ignited. The ignition control unit 83 controls the energization of the ignition coil 300 by operating the electric circuit 400 as described above using the energization signal SA.
［点火放電と筒内圧力の関係式］
　次に、点火放電と筒内圧力の関係式について説明する。 [Relational expression between ignition discharge and cylinder pressure]
Next, a relational expression between ignition discharge and in-cylinder pressure will be described.
　点火放電と筒内圧力の関係式の一例としては、キムアンダーソン氏らが導き出した関係式、通称ＫＩＭの関係式がある。ＫＩＭの関係式を式（２）に示す。
Figure JPOXMLDOC01-appb-M000004
 An example of the relational expression between the ignition discharge and the cylinder pressure is the relational expression derived by Kim Anderson et al., commonly known as the KIM relational expression. A relational expression of KIM is shown in Expression (2).
Figure JPOXMLDOC01-appb-M000004
　ＫＩＭの関係式は、誘導放電またはグロー放電時に成立するとされている。この関係式において、Ｖ２は２次電圧、Ｉ２は２次電流、ｐは筒内圧力、ｐ０は大気圧、ｌは放電路の長さを表す。したがって、Ｖ２、Ｉ２、ｐ、ｌは変数であり、ｐ０は固定値である。 It is said that the KIM relational expression holds during induction discharge or glow discharge. In this relational expression, V2 is the secondary voltage, I2 is the secondary current, p is the cylinder pressure, p0 is the atmospheric pressure, and l is the length of the discharge path. Therefore, V 2 , I 2 , p, l are variables and p 0 is a fixed value.
　上述の式（２）では、ｌ、Ｉ２、ｐ、ｐ０からＶ２を算出する。式（２）を式（３）～式（５）のように変換することで、ｌ、Ｉ２、Ｖ２、ｐ０からｐを算出することが可能となる。なお、式（５）は、上述の式（１）と同じである。
Figure JPOXMLDOC01-appb-M000005
 In the above equation (2), V 2 is calculated from l, I 2 , p, p 0 . By converting equation (2) into equations (3) to (5), p can be calculated from l, I 2 , V 2 , p 0 . Equation (5) is the same as Equation (1) above.
Figure JPOXMLDOC01-appb-M000005
［関係式のみを用いた筒内圧力の算出］
　次に、上述の式（５）のみを用いて算出した筒内圧力（ｐ）について、図７を参照して説明する。
　図７は、上述の式（５）のみを用いて算出した筒内圧力（ｐ）の精度を評価した例を示す図である。 [Calculation of in-cylinder pressure using only relational expression]
Next, the in-cylinder pressure (p) calculated using only the above equation (5) will be described with reference to FIG.
FIG. 7 is a diagram showing an example of evaluating the accuracy of the in-cylinder pressure (p) calculated using only the above equation (5).
　図７に示す各グラフの横軸は、放電開始後の時間［ｍｓｅｃ］を表す。図７に示す各グラフの縦軸は、２次電流（Ｉ２）［Ａ］、２次電圧（Ｖ２）［ｋＶ］、筒内圧力（ｐ）［ｋＰａ］を表す。 The horizontal axis of each graph shown in FIG. 7 represents the time [msec] after the start of discharge. The vertical axis of each graph shown in FIG. 7 represents secondary current (I 2 ) [A], secondary voltage (V 2 ) [kV], and in-cylinder pressure (p) [kPa].
　図７において、２次電流（Ｉ２）、２次電圧（Ｖ２）及び筒内圧力（ｐ）を示す実線は、実測値である。実測値は、２個の点火コイルを用いて時間差で連続放電することにより、放電期間を延長して測定している。これにより、測定可能期間を長くすることができ、より多くの情報から燃焼指標を算出できる。 In FIG. 7, the solid lines representing the secondary current (I 2 ), secondary voltage (V 2 ) and in-cylinder pressure (p) are measured values. The actual values are measured by extending the discharge period by using two ignition coils to continuously discharge with a time difference. As a result, the measurable period can be lengthened, and the combustion index can be calculated from more information.
　また、筒内圧力（ｐ）を示す破線は、上述の式（５）を用いて算出した算出値である。具体的には、放電路の長さ（ｌ）を電極間距離とし、２次電流（Ｉ２）と２次電圧（Ｖ２）の測定値を、関係式へ代入した結果が、破線で示す筒内圧力（ｐ）である。筒内圧力（ｐ）を示す実線は、燃焼圧センサを用いて筒内圧力（ｐ）を測定した実測値である。 Also, the dashed line indicating the in-cylinder pressure (p) is the calculated value calculated using the above equation (5). Specifically, the length (l) of the discharge path is the distance between the electrodes, and the measured values of the secondary current (I 2 ) and the secondary voltage (V 2 ) are substituted into the relational expression. This is the in-cylinder pressure (p). A solid line indicating the in-cylinder pressure (p) is an actual measurement of the in-cylinder pressure (p) using a combustion pressure sensor.
　図７に示すように、２次電流（Ｉ２）と２次電圧（Ｖ２）の波形には、放電路の伸長や再放電に伴う変動が見られる。そして、筒内圧力（ｐ）の算出値（破線）は、実測値（実線）に対して乖離と一致を繰り返している。これは、再放電開始時に放電路が電極間の最短距離で形成されているときに、上述の式（５）、すなわちＫＩＭの関係式が成立していると考えられる。そして、放電後は、筒内のガス流れの影響により放電路が伸長するため、上述の式（５）により算出した筒内圧力が、実測した筒内圧力に対して乖離すると考えられる。したがって、単に上述の式（５）を用いて筒内圧力（ｐ）を算出する場合は、精度が低下するという問題がある。 As shown in FIG. 7, the waveforms of the secondary current (I 2 ) and secondary voltage (V 2 ) show fluctuations due to extension of the discharge path and re-discharge. The calculated value (dashed line) of the in-cylinder pressure (p) repeatedly deviates from and coincides with the measured value (solid line). It is considered that the above equation (5), that is, the relational expression of KIM holds true when the discharge path is formed with the shortest distance between the electrodes at the start of redischarge. After discharge, the discharge path expands under the influence of the gas flow in the cylinder, so it is considered that the in-cylinder pressure calculated by the above equation (5) deviates from the actually measured in-cylinder pressure. Therefore, when calculating the in-cylinder pressure (p) simply by using the above equation (5), there is a problem that the accuracy is lowered.
［筒内圧力の周波数成分］
　次に、筒内圧力（ｐ）の周波数成分について、図８を参照して説明する。
　図８は、筒内圧力（ｐ）の周波数成分の例について説明する図である。 [Frequency component of in-cylinder pressure]
Next, the frequency components of the in-cylinder pressure (p) will be described with reference to FIG.
FIG. 8 is a diagram illustrating an example of frequency components of the in-cylinder pressure (p).
　図８は、図７に示す筒内圧力（ｐ）の波形について、ＦＦＴ（Fast Fourier transform）処理した結果を示している。図８に示すグラフの横軸は次数を表し、縦軸はフーリエ係数（振幅）を表す。図８において、実線は、実測値の波形をＦＦＴ処理したものであり、破線は、上述の式（５）を用いた算出値の波形をＦＦＴ処理したものである。 FIG. 8 shows the result of FFT (Fast Fourier transform) processing of the waveform of the in-cylinder pressure (p) shown in FIG. The horizontal axis of the graph shown in FIG. 8 represents the order, and the vertical axis represents the Fourier coefficient (amplitude). In FIG. 8, the solid line is the FFT-processed waveform of the actually measured value, and the dashed line is the FFT-processed waveform of the calculated value using the above equation (5).
　図８に示すように、算出値に係る破線には、３つの極大部が確認できる。各極大部を含むそれぞれの帯域を、次数が小さい方から低周波帯Ａ、中周波帯Ｂ、高周波帯Ｃとする。低周波帯Ａにおける破線は、低周波帯Ａにおける実線と略一致している。実線は、筒内圧力の成分のみであるため、この周波数帯域（低周波帯Ａ）における破線は、筒内圧力の成分であると考える。 As shown in FIG. 8, three maxima can be confirmed in the dashed line related to the calculated value. Each band including each local maximum is defined as a low frequency band A, an intermediate frequency band B, and a high frequency band C in descending order. The dashed line in the low frequency band A approximately coincides with the solid line in the low frequency band A. Since the solid line is only the in-cylinder pressure component, the dashed line in this frequency band (low frequency band A) is considered to be the in-cylinder pressure component.
　一方、中周波帯Ｂ及び高周波帯Ｃにおいて、破線は、実線から乖離している。この乖離の要因としては、放電路の伸長による２次電流（Ｉ２）と２次電圧（Ｖ２）の緩やかな変動と、再放電による２次電流（Ｉ２）と２次電圧（Ｖ２）の急激な変動が挙げられる。つまり、中周波帯Ｂにおける破線には、放電路伸長の周波数成分が含まれ、高周波帯Ｃにおける破線には、再放電の周波数成分が含まれていると考えられる。 On the other hand, in the middle frequency band B and the high frequency band C, the dashed line deviates from the solid line. Reasons for this divergence include the gradual fluctuation of the secondary current (I 2 ) and the secondary voltage (V 2 ) due to the extension of the discharge path, and the secondary current (I 2 ) and the secondary voltage (V 2 ) due to re-discharge. ) is a sharp change. That is, it is considered that the dashed line in the intermediate frequency band B contains the frequency component of discharge path extension, and the dashed line in the high frequency band C contains the frequency component of re-discharge.
　また、再放電に伴う絶縁破壊は、容量放電(アーク放電)が生じる。上述したように、ＫＩＭの関係式は、誘導放電またはグロー放電時に成立するとされている。したがって、高周波帯Ｃでは、ＫＩＭの関係式を適用できない。 In addition, dielectric breakdown accompanying re-discharge causes capacitive discharge (arc discharge). As described above, the KIM relational expression is said to hold during induction discharge or glow discharge. Therefore, in the high frequency band C, the KIM relational expression cannot be applied.
　そこで、本実施形態では、２次電流（Ｉ２）と２次電圧（Ｖ２）の波形から中周波帯Ｂ及び高周波帯Ｃ（すなわち、高周波成分）を除去し、その後、上述の式（５）を用いて筒内圧力（ｐ）を算出する。これにより、放電路伸長と再放電の周波数成分の影響を無くした算出値（筒内圧力（ｐ））を得ることができる。放電路伸長の周波数成分を除去すると、仮想的な無風状態となり、放電路の長さが電極間（電極２１０，２２０間）の最短距離に固定される。なお、本発明に係る高周波成分は、放電路伸長の周波数成分と再放電の周波数成分を含むものである。 Therefore, in this embodiment, the middle frequency band B and the high frequency band C (that is, high frequency components) are removed from the waveforms of the secondary current (I 2 ) and the secondary voltage (V 2 ), and then the above equation (5 ) to calculate the in-cylinder pressure (p). As a result, it is possible to obtain a calculated value (in-cylinder pressure (p)) that eliminates the influence of the frequency components of discharge path extension and re-discharge. When the frequency component of the discharge path extension is removed, a virtual windless state is obtained, and the length of the discharge path is fixed to the shortest distance between the electrodes (between the electrodes 210 and 220). The high-frequency component according to the present invention includes the frequency component of discharge path extension and the frequency component of re-discharge.
　中周波帯Ｂ及び高周波帯Ｃの除去を行う際に、一般的なアナログローパスフィルタ回路を用いると、応答遅れや位相ずれが生じる。その結果、算出した筒内圧力の精度が低下する。そのため、低周波帯Ａと中周波帯Ｂの間にカットオフ次数を設け、カットオフ次数以上の破線の値をゼロにして逆ＦＦＴ処理を行う。これにより、応答遅れや位相ずれを低減することができる。 If a general analog low-pass filter circuit is used when removing the middle frequency band B and the high frequency band C, response delay and phase shift will occur. As a result, the accuracy of the calculated in-cylinder pressure decreases. Therefore, a cutoff order is provided between the low frequency band A and the middle frequency band B, and the value of the dashed line above the cutoff order is set to zero to perform inverse FFT processing. Thereby, response delay and phase shift can be reduced.
［筒内圧力検出処理］
　次に、本実施形態に係る全体制御部８１により行われる筒内圧力検出処理について、図９を参照して説明する。
　図９は、本実施形態に係る筒内圧力検出処理の手順を示すフローチャートである。 [Cylinder pressure detection process]
Next, in-cylinder pressure detection processing performed by the overall control unit 81 according to the present embodiment will be described with reference to FIG.
FIG. 9 is a flow chart showing the procedure of in-cylinder pressure detection processing according to the present embodiment.
　まず、全体制御部８１は、２次電流（Ｉ２）及び２次電圧（Ｖ２）を検出する（Ｓ１）。Ｓ１の処理では、２次電流（Ｉ２）及び２次電圧（Ｖ２）の放電波形（放電期間の波形）を検出する。 First, the overall control unit 81 detects secondary current (I 2 ) and secondary voltage (V 2 ) (S1). In the processing of S1, the discharge waveform (discharge period waveform) of the secondary current (I 2 ) and the secondary voltage (V 2 ) is detected.
　次に、全体制御部８１は、放電波形から高周波成分を除去し、除去した波形から２次電流（Ｉ２）及び２次電圧（Ｖ２）の値を取得する（Ｓ２）。Ｓ２の処理では、予め定められたカットオフ次数以上（次数範囲）をゼロとするようにＦＦＴ処理を行い、その後、逆ＦＦＴ処理を行うことのより、高周波成分を除去する。なお、カットオフ次数は、燃焼圧センサ（実測値を得るために用意した基準センサ）を用いて取得した筒内圧力の波形における周波数成分に基づいて定める。 Next, the general control unit 81 removes the high frequency component from the discharge waveform and obtains the values of the secondary current (I 2 ) and the secondary voltage (V 2 ) from the removed waveform (S2). In the processing of S2, FFT processing is performed so that a predetermined cutoff order or more (order range) is zero, and then inverse FFT processing is performed to remove high frequency components. The cutoff order is determined based on the frequency component in the waveform of the in-cylinder pressure obtained using the combustion pressure sensor (the reference sensor prepared for obtaining the actual measurement value).
　次に、全体制御部８１は、ＫＩＭの関係式を変換して得た上述の式（５）を用いて筒内圧力（ｐ）を算出する（Ｓ３）。Ｓ３の処理後、全体制御部８１は、筒内圧力検出処理を終了する。このように、２次電流（Ｉ２）及び２次電圧（Ｖ２）の放電波形から高周波成分を除去することにより、仮想的な無風状態にすることができ、放電路伸長の影響を取り除くことができる。すなわち、放電路の長さを電極間の最短距離に固定することができる。その結果、筒内圧力（ｐ）を精度良く検知（算出）することができる。 Next, the overall control unit 81 calculates the in-cylinder pressure (p) using the above-described equation (5) obtained by converting the KIM relational expression (S3). After the process of S3, the general control unit 81 ends the in-cylinder pressure detection process. By removing high-frequency components from the discharge waveforms of the secondary current (I 2 ) and secondary voltage (V 2 ) in this way, it is possible to create a virtual no-wind condition and remove the effect of the discharge path expansion. can be done. That is, the length of the discharge path can be fixed to the shortest distance between the electrodes. As a result, the in-cylinder pressure (p) can be accurately detected (calculated).
　図１０は、本実施形態に係る筒内圧力（ｐ）の検出精度を評価した例を示す図である。図１０に示す各グラフの横軸は、放電開始後の時間［ｍｓｅｃ］を表す。図７に示す各グラフの縦軸は、２次電流（Ｉ２）［Ａ］、２次電圧（Ｖ２）［ｋＶ］、筒内圧力（ｐ）［ｋＰａ］を表す。 FIG. 10 is a diagram showing an example of evaluating the detection accuracy of the in-cylinder pressure (p) according to this embodiment. The horizontal axis of each graph shown in FIG. 10 represents time [msec] after the start of discharge. The vertical axis of each graph shown in FIG. 7 represents secondary current (I 2 ) [A], secondary voltage (V 2 ) [kV], and in-cylinder pressure (p) [kPa].
　図１０において、２次電流（Ｉ２）及び２次電圧（Ｖ２）を示す実線は、上述したＦＦＴ処理及び逆ＦＦＴ処理を行って高周波成分を除去したものである。また、筒内圧力（ｐ）を示す実線は、燃焼圧センサを用いて筒内圧力（ｐ）を測定した実測値である。筒内圧力（ｐ）を示す破線は、上述の式（５）を用いて算出した算出値である。具体的には、放電路の長さ（ｌ）を電極間距離とし、高周波成分を除去した２次電流（Ｉ２）と２次電圧（Ｖ２）を、関係式へ代入した結果が、破線で示す筒内圧力（ｐ）である。 In FIG. 10, the solid lines representing the secondary current (I 2 ) and secondary voltage (V 2 ) are obtained by removing the high frequency components by performing the above-described FFT processing and inverse FFT processing. Further, the solid line indicating the in-cylinder pressure (p) is the measured value of the in-cylinder pressure (p) measured using the combustion pressure sensor. A dashed line indicating the in-cylinder pressure (p) is a calculated value calculated using the above equation (5). Specifically, the length (l) of the discharge path is the distance between the electrodes, and the result of substituting the secondary current (I 2 ) and the secondary voltage (V 2 ) from which high frequency components are removed into the relational expression is shown by the dashed line. is the in-cylinder pressure (p) indicated by .
　上述の式（５）を用いて算出した算出値である破線は、燃焼圧センサを用いた実測値である実線との乖離が小さくなる。これにより、筒内圧力（ｐ）の検知精度（算出精度）が向上していることが確認できる。その結果、気筒別の燃焼制御を高精度に行うことができ、車両の燃費を向上することができる。 The dashed line, which is the calculated value calculated using the above formula (5), has a small divergence from the solid line, which is the actually measured value using the combustion pressure sensor. As a result, it can be confirmed that the detection accuracy (calculation accuracy) of the in-cylinder pressure (p) is improved. As a result, combustion control for each cylinder can be performed with high accuracy, and fuel efficiency of the vehicle can be improved.
２.まとめ
　以上説明したように、上述した実施形態に係る筒内圧力検出方法は、２次側コイル（２次側コイル３２０）の情報を用いて筒内圧力（ｐ）を検出する。この筒内圧力検出方法では、２次側コイルの放電波形から高周波成分を除去し、高周波成分を除去した放電波形から２次電流（Ｉ２）及び２次電圧（Ｖ２）の情報を取得する。そして、上述の式（１）（式（５））から筒内圧力（ｐ）を算出する。これにより、点火プラグ（点火プラグ２００）の電極間（中心電極２１０と外側電極２２０との間）を仮想的な無風状態にして、放電路伸長や再放電の影響を取り除いて筒内圧力（ｐ）を検出することができる。その結果、精度の良い筒内圧力（ｐ）の検出を行うことができ、気筒の部品特性に合わせた燃焼制御を実現することができる。したがって、燃費の向上を図ることができる。また、燃焼圧センサを用いて筒内圧力（ｐ）を検出する必要がないため、部品点数を削減して内燃機関システムの低コスト化を実現することができる。 2. Summary As described above, the in-cylinder pressure detection method according to the above-described embodiment detects the in-cylinder pressure (p) using information on the secondary coil (secondary coil 320). In this in-cylinder pressure detection method, high-frequency components are removed from the discharge waveform of the secondary coil, and information on the secondary current (I 2 ) and secondary voltage (V 2 ) is obtained from the discharge waveform from which the high-frequency components have been removed. . Then, the in-cylinder pressure (p) is calculated from the above equations (1) (equation (5)). As a result, the space between the electrodes (between the center electrode 210 and the outer electrode 220) of the spark plug (spark plug 200) is placed in a virtual windless state, and the effects of discharge path elongation and re-discharge are eliminated, and the cylinder pressure (p ) can be detected. As a result, the in-cylinder pressure (p) can be detected with high accuracy, and combustion control can be achieved in accordance with the characteristics of the parts of the cylinder. Therefore, it is possible to improve fuel efficiency. Moreover, since it is not necessary to detect the in-cylinder pressure (p) using a combustion pressure sensor, it is possible to reduce the number of parts and reduce the cost of the internal combustion engine system.
　また、上述した実施形態に係る筒内圧力検出方法において、式（１）における放電路の長さ（ｌ）は、点火プラグ（点火プラグ２００）における電極間の最短距離である。これにより、再現性の高い電極間距離を放電路の長さとして用いることができる。また、放電路の長さの検知を不要にすることができる。 Also, in the in-cylinder pressure detection method according to the embodiment described above, the length (l) of the discharge path in equation (1) is the shortest distance between the electrodes in the spark plug (spark plug 200). Thereby, the inter-electrode distance with high reproducibility can be used as the length of the discharge path. Also, detection of the length of the discharge path can be made unnecessary.
　また、上述した実施形態に係る筒内圧力検出方法において、高周波成分の除去は、２次電流と２次電圧の波形データについて予め定めた次数範囲をゼロとするようにＦＦＴ処理を行い、その後逆ＦＦＴ処理を行うことにより達成される。これにより、高周波成分を除去すると共に、応答遅れや位相ずれを低減することができる。 Further, in the in-cylinder pressure detection method according to the above-described embodiment, the removal of high-frequency components is performed by performing FFT processing so that a predetermined order range of the waveform data of the secondary current and secondary voltage is zero, and then performing reverse processing. It is achieved by performing FFT processing. As a result, high frequency components can be removed, and response delay and phase shift can be reduced.
　また、上述した実施形態に係る筒内圧力検出方法において、予め定めた次数範囲は、燃焼圧センサを用いて取得した実測値の圧力波形における周波数成分から定める。これにより、除去する高周波成分を正確に定めることができ、放電路伸長の周波数成分や再放電の周波数成分をより確実に除去することができる。 Further, in the in-cylinder pressure detection method according to the above-described embodiment, the predetermined order range is determined from the frequency components in the pressure waveform of the measured values obtained using the combustion pressure sensor. As a result, the high-frequency component to be removed can be accurately determined, and the frequency component of discharge path extension and the frequency component of re-discharge can be removed more reliably.
　また、上述した実施形態に係る内燃機関制御装置（制御装置１）は、１次側コイル（１次側コイル３１０）と、１次側コイルの通電が遮断されると、起電力が生じる２次側コイルと、２次側コイルに接続された点火プラグ（点火プラグ２００）とを有する。そして、２次側コイルの放電波形から高周波成分を除去し、高周波成分を除去した放電波形から２次電流及び２次電圧の情報を取得し、上述の式（１）（式（５））から筒内圧力を算出する制御部（全体制御部８１）を備える。これにより、放電路伸長や再放電の影響を取り除いて筒内圧力（ｐ）を検出することができる。その結果、精度の良い筒内圧力（ｐ）の検出を行うことができ、気筒の部品特性に合わせた燃焼制御を実現することができる。したがって、燃費の向上を図ることができる。また、燃焼圧センサを用いて筒内圧力（ｐ）を検出する必要がないため、部品点数を削減して内燃機関システムの低コスト化を実現することができる。 Further, the internal combustion engine control device (control device 1) according to the above-described embodiment includes a primary coil (primary coil 310) and a secondary coil that generates an electromotive force when energization of the primary coil is interrupted. It has a side coil and a spark plug (spark plug 200) connected to the secondary coil. Then, the high frequency component is removed from the discharge waveform of the secondary coil, the information of the secondary current and the secondary voltage is obtained from the discharge waveform from which the high frequency component is removed, and from the above equations (1) (equation (5)) A control unit (general control unit 81) that calculates the in-cylinder pressure is provided. As a result, the in-cylinder pressure (p) can be detected without the effects of discharge path extension and re-discharge. As a result, the in-cylinder pressure (p) can be detected with high accuracy, and combustion control can be achieved in accordance with the characteristics of the parts of the cylinder. Therefore, it is possible to improve fuel efficiency. Moreover, since it is not necessary to detect the in-cylinder pressure (p) using a combustion pressure sensor, it is possible to reduce the number of parts and reduce the cost of the internal combustion engine system.
　なお、本発明に係る筒内圧力検出方法並びに内燃機関制御装置は、筒内圧センサ（燃焼圧センサ）を備えた内燃機関にも適用可能である。その場合は、筒内圧センサの出力と筒内圧力検出方法を用いて検出した筒内圧力（ｐ）とを比較することで筒内圧センサの診断を実施することも可能である。また、筒内圧センサが故障した場合には、本発明に係る筒内圧検出方法を用いて筒内圧力を検出して、内燃機関を制御することでフェールオペレーショナルな制御を実現可能となる。 The in-cylinder pressure detection method and the internal combustion engine control device according to the present invention can also be applied to an internal combustion engine equipped with an in-cylinder pressure sensor (combustion pressure sensor). In that case, it is possible to diagnose the in-cylinder pressure sensor by comparing the output of the in-cylinder pressure sensor and the in-cylinder pressure (p) detected using the in-cylinder pressure detection method. Further, when the in-cylinder pressure sensor fails, the in-cylinder pressure is detected using the in-cylinder pressure detection method according to the present invention, and the internal combustion engine is controlled to realize fail-operational control.
　以上、本発明の筒内圧力検出方法、筒内圧センサ診断方法及び内燃機関制御装置の実施形態について、その作用効果も含めて説明した。しかしながら、本発明の筒内圧力検出方法、筒内圧センサ診断方法及び内燃機関制御装置は、上述の実施形態に限定されるものではなく、請求の範囲に記載した発明の要旨を逸脱しない範囲内で種々の変形実施が可能である。 The embodiments of the in-cylinder pressure detection method, the in-cylinder pressure sensor diagnostic method, and the internal combustion engine control device of the present invention have been described above, including their effects. However, the in-cylinder pressure detection method, the in-cylinder pressure sensor diagnosis method, and the internal combustion engine control device of the present invention are not limited to the above-described embodiments, and are within the scope of the invention described in the claims. Various alternative implementations are possible.
　また、上述した実施形態は、本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施形態の構成の一部を他の実施形態の構成に置き換えることが可能であり、また、ある実施形態の構成に他の実施形態の構成を加えることも可能である。また、各実施形態の構成の一部について、他の構成の追加・削除・置換をすることが可能である。 In addition, the above-described embodiments have been described in detail for easy-to-understand description of the present invention, and are not necessarily limited to those having all the described configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.
　例えば、上述した実施形態では、全体制御部８１が筒内圧力検出処理を行う構成にした。しかし、本発明に係る筒内圧力検出処理は、制御装置１とは別に設けた制御部、例えば、デジタルシグナルプロセッサ（ＤＮＰ）としてもよい。この場合は、２次側コイルのノイズが制御装置１に混入することを防止することができる。また、制御装置１とは別に筒内圧力検出処理を行う制御部を設けた場合は、その制御部と制御装置１によって内燃機関制御装置が構成される。 For example, in the embodiment described above, the overall control unit 81 is configured to perform the in-cylinder pressure detection process. However, the in-cylinder pressure detection process according to the present invention may be performed by a control unit provided separately from the control device 1, such as a digital signal processor (DNP). In this case, it is possible to prevent the noise of the secondary coil from entering the control device 1 . Further, when a control unit for performing in-cylinder pressure detection processing is provided separately from the control device 1, the control unit and the control device 1 constitute an internal combustion engine control device.
　１…制御装置、　１０…アナログ入力部、　２０…デジタル入力部、　３０…Ａ／Ｄ変換部、　４０…ＲＡＭ、　５０…ＭＰＵ、　６０…ＲＯＭ、　７０…Ｉ／Ｏポート、　８０…出力回路、　８１…全体制御部、　８２…燃料噴射制御部、　８３…点火制御部、　８４…気筒判別部、　８５…角度情報生成部、　８６…回転数情報生成部、　８７…吸気量計測部、　８８…負荷情報生成部、　８９…水温計測部、　１００…内燃機関、　１１０…エアクリーナ、　１１１…吸気管、　１１２…吸気マニホールド、　１１３…スロットル弁、　　１１５…吸気温センサ、　１２０…リングギア、　１２３…クランクシャフト、　１２５…アクセルペダル、　１３０…燃料タンク、　１３１…燃料ポンプ、　１３２…プレッシャレギュレータ、　１３３…燃料配管、　１３４…燃料噴射装置、　１５０…気筒、　１５１…吸気弁、　１５２…排気弁、　１６０…排気マニホールド、　１６１…三元触媒、　１７０…ピストン、　２００…点火プラグ、　２１０…中心電極、　２１１…放電路、　２２０…外側電極、　２３０…絶縁体、　３００…点火コイル、　３１０…１次側コイル、　３２０…２次側コイル、　３３０…直流電源、　３４０…イグナイタ（通電制御回路）、　４００…電気回路 1... control device, 10... analog input unit, 20... digital input unit, 30... A/D conversion unit, 40... RAM, 50... MPU, 60... ROM, 70... I/O port, 80... output circuit, 81 ... general control section, 82 ... fuel injection control section, 83 ... ignition control section, 84 ... cylinder determination section, 85 ... angle information generation section, 86 ... rotation speed information generation section, 87 ... intake air amount measurement section, 88 ... load information Generation unit 89 Water temperature measurement unit 100 Internal combustion engine 110 Air cleaner 111 Intake pipe 112 Intake manifold 113 Throttle valve 115 Intake air temperature sensor 120 Ring gear 123 Crankshaft 125 Accelerator pedal 130 Fuel tank 131 Fuel pump 132 Pressure regulator 133 Fuel pipe 134 Fuel injection device 150 Cylinder 151 Intake valve 152 Exhaust valve 160 Exhaust manifold 161 ...three-way catalyst 170...piston 200...spark plug 210...center electrode 211...discharge path 220...outer electrode 230...insulator 300...ignition coil 310...primary coil 320...secondary side coil, 330... DC power supply, 340... igniter (energization control circuit), 400... electric circuit

Claims (6)

  1. 　１次側コイルと、前記１次側コイルの通電が遮断されると、起電力が生じる２次側コイルと、前記２次側コイルに接続された点火プラグとを有する内燃機関における前記２次側コイルの情報を用いて筒内圧力を検出する筒内圧力検出方法であって、
    　前記２次側コイルの放電波形から高周波成分を除去し、
    　高周波成分を除去した前記放電波形から２次電流及び２次電圧の情報を取得し、以下の式（１）から筒内圧力を算出する
    　筒内圧力検出方法。
    （数１）
    Figure JPOXMLDOC01-appb-I000001
    　ただし、Ｖ２は２次電圧、Ｉ２は２次電流、ｐは筒内圧力、ｐ０は大気圧、ｌは放電路の長さである。     The secondary side in an internal combustion engine having a primary side coil, a secondary side coil that generates an electromotive force when energization of the primary side coil is interrupted, and a spark plug connected to the secondary side coil. A cylinder pressure detection method for detecting cylinder pressure using coil information,
    removing high frequency components from the discharge waveform of the secondary coil;
    A method of detecting in-cylinder pressure, wherein information on a secondary current and a secondary voltage is obtained from the discharge waveform from which high-frequency components have been removed, and the in-cylinder pressure is calculated from the following equation (1).
    (Number 1)
    Figure JPOXMLDOC01-appb-I000001
    where V2 is the secondary voltage, I2 is the secondary current, p is the cylinder pressure, p0 is the atmospheric pressure, and l is the length of the discharge path.
  2. 　前記放電路の長さは、前記点火プラグにおける電極間の最短距離である
    　請求項１に記載の筒内圧力検出方法。     The in-cylinder pressure detection method according to claim 1, wherein the length of the discharge path is the shortest distance between electrodes in the spark plug.
  3. 　前記高周波成分の除去は、２次電流と２次電圧の波形データについて予め定めた次数範囲をゼロとするようにＦＦＴ処理を行い、その後逆ＦＦＴ処理を行うことにより達成される
    　請求項１又は２に記載の筒内圧力検出方法。     3. The removal of the high frequency component is achieved by performing FFT processing so that a predetermined order range of the waveform data of the secondary current and the secondary voltage is zero, and then performing inverse FFT processing. 3. The in-cylinder pressure detection method according to .
  4. 　前記予め定めた次数範囲は、燃焼圧センサを用いて取得した実測値の圧力波形における周波数成分から定める
    　請求項３に記載の筒内圧力検出方法。     4. The in-cylinder pressure detection method according to claim 3, wherein the predetermined order range is determined from frequency components in a pressure waveform of actually measured values obtained using a combustion pressure sensor.
  5. 　請求項１に記載の筒内圧検出方法で検出した筒内圧力と、筒内圧センサの出力とを用いて、該筒内圧センサの診断を実施する筒内圧センサ診断方法。 A cylinder pressure sensor diagnosis method for diagnosing the cylinder pressure sensor using the cylinder pressure detected by the cylinder pressure detection method according to claim 1 and the output of the cylinder pressure sensor.
  6. 　１次側コイルと、前記１次側コイルの通電が遮断されると、起電力が生じる２次側コイルと、前記２次側コイルに接続された点火プラグとを有する内燃機関を制御する内燃機関制御装置において、
    　前記２次側コイルの放電波形から高周波成分を除去し、高周波成分を除去した前記放電波形から２次電流及び２次電圧の情報を取得し、以下の式（１）から筒内圧力を算出する制御部を備える
    　内燃機関制御装置。
    （数１）
    Figure JPOXMLDOC01-appb-I000002
    　ただし、Ｖ２は２次電圧、Ｉ２は２次電流、ｐは筒内圧力、ｐ０は大気圧、ｌは放電路の長さである。     An internal combustion engine that controls an internal combustion engine having a primary coil, a secondary coil that generates an electromotive force when the primary coil is deenergized, and an ignition plug connected to the secondary coil. in the controller,
    High frequency components are removed from the discharge waveform of the secondary coil, information on the secondary current and secondary voltage is obtained from the discharge waveform from which the high frequency components have been removed, and the in-cylinder pressure is calculated from the following equation (1). An internal combustion engine controller comprising a controller.
    (Number 1)
    Figure JPOXMLDOC01-appb-I000002
    where V2 is the secondary voltage, I2 is the secondary current, p is the cylinder pressure, p0 is the atmospheric pressure, and l is the length of the discharge path.
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