Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D41/2096—Output circuits, e.g. for controlling currents in command coils for controlling piezoelectric injectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/04—Introducing corrections for particular operating conditions
  • F02D41/08—Introducing corrections for particular operating conditions for idling
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D2041/2068—Output circuits, e.g. for controlling currents in command coils characterised by the circuit design or special circuit elements
  • F02D2041/2082—Output circuits, e.g. for controlling currents in command coils characterised by the circuit design or special circuit elements the circuit being adapted to distribute current between different actuators or recuperate energy from actuators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/008—Controlling each cylinder individually
  • F02D41/0082—Controlling each cylinder individually per groups or banks

Definitions

• the invention relates to a fuel injection control device and fuel injection control method for an internal combustion engine, which change an amount of driving energy applied to an injector on the basis of an engine operating state, and a vehicle equipped with the fuel injection control device.
• multi-stage injection control In a recent diesel engine, so-called multi-stage injection control is executed.
• the multi-stage injection control carries out multiple times of fuel injection in each combustion cycle for the purpose of improving emissions, suppressing noise, and the like.
• a fuel injection valve is required to have high-speed operation performance because of the reason why an extremely small amount of fuel injection is required, or the like. Then, in order to satisfy such high-speed operation performance, a piezoelectric injector having an excellent response has become a focus of attention.
• the piezoelectric injector drives a nozzle in such a manner that a piezoelectric element extends or contracts as the piezoelectric element is charged or discharged to thereby inject fuel.
• the piezoelectric element has temperature dependency, and the amount of extension or contraction significantly varies with temperature. Specifically, as shown in FIG. 5, the apparent capacitance C of the piezoelectric element, which correlates the' electric charge stored in the piezoelectric element with the voltage of the piezoelectric element, increases as the temperature increases. In this way, the electrical characteristic of the piezoelectric element varies depending on the temperature, so it is difficult to control the displacement of the piezoelectric element using an electrical state quantity, such as voltage and current.
• FIG. 6 shows the correlation between the piezoelectric modulus d of a piezoelectric element and the temperature of the piezoelectric element.
• the piezoelectric modulus d of the piezoelectric element is obtained as the ratio of a displacement with respect to a voltage.
• the piezoelectric modulus d of the piezoelectric element increases as the temperature increases. Therefore, even when the displacement is intended to be controlled using the voltage of the piezoelectric element, high control accuracy cannot be obtained.
• JP-A-2009-65812 Japanese Patent Application Publication No. 2009-65812
• fuel injection is controlled by operating the amount of driving energy applied to each piezoelectric element instead of operating the electrical state quantity.
• the reason why such control is executed is that the displacement of each piezoelectric element may be made substantially constant when the amount of driving energy E applied to each piezoelectric element is the same, irrespective of the temperature of each piezoelectric element. This fact may be simply described as follows. That is, when the amount of driving energy E applied to a piezoelectric element is constant, as the capacitance C of the piezoelectric element increases with an increase in the temperature owing to the relationship shown in FIG.
• the invention provides a fuel injection control device and fuel injection control method for an internal combustion engine, which are able to change an amount of driving energy without any deviation of a fuel injection amount, and a vehicle equipped with the fuel injection control device.
• a first aspect of the invention relates to a fuel injection control device for an internal combustion engine, which changes an amount of driving energy applied to an injector on the basis of an engine operating state.
• the fuel injection control device includes an electronic control unit that, when the injector is carrying out fuel injection at the time of changing the amount of driving energy, allows the injector to accomplish the fuel injection at the pre-changed amount of driving energy.
• the amount of driving energy is not changed for fuel injection that is being carried out at that moment but the injector is allowed to accomplish the fuel injection at the pre-changed amount of driving energy. Therefore, with the above configuration, the amount of driving energy is not changed during fuel injection. Thus, with the above configuration, the amount of driving energy may be changed without any deviation of the fuel injection amount.
• the electronic control unit may change the amount of driving energy during a period from completion of fuel injection that is being carried out at the time when a request to change the amount of driving energy is issued to start of the next fuel injection.
• the amount of driving energy is not changed at that moment but the amount of driving energy is changed during a period from completion of fuel injection that is being carried out to start of the next fuel injection. Therefore, with the above configuration, the amount of driving energy is not changed during fuel injection. Thus, with the above configuration, the amount of driving energy may be changed without any deviation of the fuel injection amount.
• the fuel injection control device may further include a drive circuit that is provided for each cylinder group and that drives the corresponding injector, wherein, at the time of changing the amount of driving energy, the electronic control unit may cause the drive circuit that is executing fuel injection to accomplish the fuel injection at the pre-changed amount of driving energy, and may change the amount of driving energy of the drive circuit that is not executing fuel injection.
• the drive circuit that is executing fuel injection is not caused to change the amount of driving energy at that moment but is caused to accomplish the fuel injection at the pre-changed amount of driving energy. Then, the amount of driving energy of the drive circuit that is not executing fuel injection is changed. Therefore, with the above configuration, the amount of driving energy is not changed during fuel injection. Thus, with the above configuration, the amount of driving energy may be changed without any deviation of the fuel injection amount.
• the electronic control unit may change the amount of driving energy of the drive circuit in response to a request to change the amount of driving energy on condition that the drive circuit is in a standby state where the drive circuit is not executing fuel injection.
• the amount of driving energy of that drive circuit is not changed unless in a standby state where the drive circuit is not executing fuel injection. That is, with the above configuration, the amount of driving energy of the drive circuit that is executing fuel injection is not changed but is caused to accomplish the fuel injection at the pre-changed amount of driving energy. Therefore, with the above configuration, the amount of driving energy is not changed during fuel injection. Thus, with the above configuration, the amount of driving energy may be changed without any deviation of the fuel injection amount.
• the electronic control unit may change the amount of driving energy on the basis of a change of the engine operating state between during idle operation of the internal combustion engine and during normal operation, other than the idle operation, of the internal combustion engine.
• a second aspect of the invention relates to a fuel injection control method for an internal combustion engine, which changes an amount of driving energy applied to an injector on the basis of an engine operating state.
• the fuel injection control method includes: determining whether a precondition for changing the amount of driving energy is satisfied; determining whether the injector is carrying out fuel injection; and when the precondition for changing the amount of driving energy is satisfied and the injector is carrying out fuel injection, allowing the injector to accomplish the fuel injection at the pre-changed amount of driving energy.
• a third aspect of the invention relates to a vehicle that includes the fuel injection control device for an internal combustion engine according to the first aspect of the invention.
• FIG. 1 is a diagram that schematically shows the overall configuration of a fuel injection control device for an internal combustion engine according to an embodiment of the invention
• FIG. 2 is a cross-sectional view that shows the side cross-sectional structure of a piezoelectric injector employed in the embodiment
• FIG. 3 is a time chart that shows a mode of driving energy amount change control according to the embodiment
• FIG. 4 is a flowchart that shows the procedure of driving energy amount change determination routine employed in the embodiment
• FIG. 5 is a graph that shows the correlation between the apparent capacitance C of a piezoelectric element and the temperature of the piezoelectric element.
• FIG. 6 is a graph that shows the correlation between the piezoelectric modulus d of a piezoelectric element and the temperature of the piezoelectric element.
• the fuel injection control device is applied to a V-eight diesel engine.
• Four cylinders that is, a first cylinder #1, a third cylinder # 3, a fifth cylinder # 5 and a seventh cylinder #7, are arranged in the left bank of the diesel engine, and four cylinders, that is, a second cylinder #2, a fourth cylinder #4, a sixth cylinder #6 and an eighth cylinder #8, are arranged in the right bank of the diesel engine.
• ignition takes place in the diesel engine in the order of the first cylinder #1 , the second cylinder #2, the seventh cylinder #7, the third cylinder #3, the fourth cylinder #4, the fifth cylinder #5, the sixth cylinder #6 and the eighth cylinder #8.
• fuel injection is always carried out in any one of the cylinders during engine operation.
• FIG. 1 shows the overall structure of a fuel injection control device according to the present embodiment.
• the fuel injection control device includes an electronic control unit (ECU) 10 and two drive circuits (EDUs).
• the two drive circuits include a first drive circuit 11 and a second drive circuit 12.
• the electronic control unit 10 determines the injection amount and injection timing of fuel to issue a command to the drive circuits 11 and 12 on the basis of a detected diesel engine operating condition, such as an engine rotational speed and an accelerator operation amount. Then, the drive circuits 11 and 12 drive injectors I J1 to INJ8 on the basis of the command.
• the first drive circuit (EDU1) 11 has charge of a cylinder group formed of four cylinders of the first cylinder #1 , the fourth cylinder #4, the sixth cylinder #6 and the seventh cylinder #7. That is, the first drive circuit 11 drives the injector INJl of the first cylinder #1 , the injector INJ4 of the fourth cylinder #4, the injector INJ6 of the sixth cylinder #6 and the injector INJ7 of the seventh cylinder #7.
• the second drive circuit (EDU2) 12 has charge of a cylinder group formed of four cylinders of the second cylinder #2, the third cylinder #3, the fifth cylinder #5 and the eighth cylinder #8.
• the second drive circuit 12 drives the injector INJ2 of the second cylinder #2, the injector INJ3 of the third cylinder #3, the injector INJ5 of the fifth cylinder #5 and the injector INJ8 of the eighth cylinder #8. That is, in the present embodiment in which the order of ignition is set as described above, the two drive circuits 11 and 12 alternately execute fuel injection.
• FIG. 2 shows the side cross-sectional structure of each of the injectors INJl to INJ8.
• piezoelectric injectors that are driven by piezoelectric elements are employed as the injectors INJl to INJ8.
• a needle accommodating portion 21, which is a cylindrical columnar space, is provided at the distal end of a body 20 of each piezoelectric injector. Then, a nozzle needle 22 is accommodated inside the needle accommodating portion 21 so as to be displaceable in the axial direction.
• the nozzle needle 22 is seated on an annular needle seat portion 23 to shut off the needle accommodating portion 21 from the outside, that is, a combustion chamber of the diesel engine.
• the needle seat portion 23 is formed at the distal end portion of the body 20.
• the nozzle needle 22 is separated from the needle seat portion 23 to provide fluid communication between the needle accommodating portion 21 and the outside.
• a high-pressure fuel passage 24 is connected to the needle accommodating portion 21 and high-pressure fuel discharged by a fuel pump is supplied through the high-pressure fuel passage 24.
• the back surface side that is, the side opposite to the side facing the needle seat portion 23, of the nozzle needle 22 faces a back pressure chamber 25.
• Fuel from the high-pressure fuel passage 24 is supplied to the back pressure chamber 25 via an orifice 26.
• a needle spring 27 is arranged in the back pressure chamber 25. The needle spring 27 urges the nozzle needle 22 toward the needle seat portion 23.
• the back pressure chamber 25 is communicable with a low-pressure fuel passage 30 via a valve 28.
• the low-pressure fuel passage 30 is shut off from the back pressure chamber 25.
• the valve 28 is displaced toward the distal end side of the body 20, the low-pressure fuel passage 30 is brought into fluid communication with the back pressure chamber 25.
• the side of the valve 28 adjacent to the valve seat portion 29 is coupled to a small-diameter piston 32 via a pressure pin 31.
• the rear side of the small-diameter piston 32 faces the distal end side of a large-diameter piston 33 that is larger in diameter than the small-diameter piston 32.
• a displacement transmitting chamber 34 is defined by the small-diameter piston 32, the large-diameter piston 33 and the inner peripheral surface of the body 20, and then the displacement transmitting chamber 34 is filled with fluid, such as fuel.
• the side of the large-diameter piston 33 adjacent to the rear side of the body 20 is coupled to a piezoelectric element 35.
• the piezoelectric element 35 is fixed to the body 20 at its back surface side of the side facing the large-diameter piston 33.
• the thus arranged piezoelectric element 35 is formed of a stack in which a plurality of piezoelectric elements are stacked on top of each other (piezoelectric stack), and the piezoelectric stack extends or contracts owing to inverse piezoelectric effect to thereby function as an actuator. Electrically, the piezoelectric element 35 is a capacitive load, and extends when it is charged or contracts when it is discharged.
• the piezoelectric element 35 installed in each injector according to the present embodiment uses a piezoelectric element made of a piezoelectric material, such as PZT (lead zirconate titanate).
• the piezoelectric injector when the piezoelectric element 35 is not supplied with current and is contracted, the pressure of high-pressure fuel in the high-pressure fuel passage 24 is applied to the valve 28 and the small-diameter piston 32, so the valve 28 and the small-diameter piston 32 are placed at the rear side of the body 20.
• the back pressure chamber 25 at this time is shut off by the valve 28 from the low-pressure fuel passage 30. Therefore, the nozzle needle 22 at this time is pressed toward the distal end side of the body 20 by the pressure of fuel in the back pressure chamber 25 and the urging force of the needle spring 27, so the nozzle needle 22 is in a valve closed state where the nozzle needle 22 is seated on the needle seat portion 23.
• the operation of the piezoelectric element 35 of each piezoelectric injector has temperature dependency and the piezoelectric modulus d increases as the temperature increases. Then, in the present embodiment, in order to appropriately drive each piezoelectric injector irrespective of the temperature dependency of the piezoelectric element 35, the amount of driving energy applied to the piezoelectric element 35 is operated to control fuel injection.
• the injector is allowed to accomplish the fuel injection at the pre-changed amount of driving energy. Then, the amount of driving energy is changed during a period from completion of fuel injection that is being carried out at the time when a request to change the amount of driving energy is issued to start of the next fuel injection.
• the drive circuit 11 or 12 that is executing fuel injection is caused to accomplish the fuel injection at the pre-changed amount of driving energy, and the driving circuit 11 or 12 that is not executing fuel injection changes the amount of driving energy.
• the amount of driving energy of the drive circuit in response to a request to change the amount of driving energy, is changed on condition that the drive circuit is in a standby state where the drive circuit is not executing fuel injection.
• the electronic control unit 10 changes the offset of the injection time (correction of the injection time with the amount of driving energy) in synchronization with changing the amount of driving energy.
• FIG. 3 shows a mode of control for changing the amount of driving energy according to the present embodiment.
• the precondition for changing from normal energy drive to idling low energy drive is satisfied.
• the precondition is satisfied, for example, when the accelerator operation amount is "0" and the engine rotational speed is lower than or equal to "1000 rpm".
• the electronic control unit 10 determines whether to change the amount of driving energy at the time of updating a cylinder number that indicates which cylinder in which ignition currently takes place.
• the second cylinder #2 is an ignition cylinder at time t2 when initial change determination as to whether to change the amount of driving energy is made, and fuel injection into the second cylinder #2 is started at time t2.
• Fuel injection into the second cylinder #2 is executed by the second drive circuit 12.
• the first drive circuit 11 at this time is in a standby state where the first drive circuit 11 is not executing fuel injection.
• the second drive circuit 12 maintains the pre-changed amount of driving energy, and only the first drive circuit 11 in a standby state changes the amount of driving energy. Then, changing the amount of driving energy in the second drive circuit 12 is suspended until time t3 at which the next change determination is made.
• FIG. 4 shows a flowchart of driving energy amount change determination routine employed in the present embodiment. The process of the routine is repeatedly executed by the electronic control unit 10 each time the cylinder number is updated.
• the electronic control unit 10 When the routine is started, the electronic control unit 10 initially checks in step SI 00 whether a precondition for changing from normal energy drive to idling low energy drive is satisfied. Here, the electronic control unit 10 causes the process to proceed to step S I 01 when the precondition is satisfied (SI 00: YES); whereas the electronic control unit 10 causes the process to proceed to step S I 04 when the precondition is not satisfied (SI 00: NO).
• step SlOl the electronic control unit 10 determines whether the first drive circuit 11 is currently executing fuel injection, that is, the first drive circuit 11 has charge of the injector of the ignition cylinder at that moment.
• the electronic control unit 10 issues a command for idling low energy drive to the first drive circuit 11 in step SI 02, and then ends the process of the current routine.
• the electronic control unit 10 issues a command for idling low energy drive to the second drive circuit 12 in step SI 03 and then ends the process of the current routine.
• the electronic control unit 10 determines whether the first drive circuit 11 is currently executing fuel injection, that is, the first drive circuit 11 has charge of the injector of the ignition cylinder at that moment.
• the electronic control unit 10 issues a command for normal energy drive to the first drive circuit 11 in step SI 05 and then ends the process of the current routine.
• the electronic control unit 10 issues a command for normal energy drive to the second drive circuit 12 in step SI 06 and then ends the process of the current routine.
• the drive circuit 11 or 12 of the electronic control unit 10 which is executing fuel injection, is caused to accomplish the fuel injection at the pre-changed amount of driving energy, and the drive circuit 11 or 12 that is not executing fuel injection changes the amount of driving energy. That is, in the present embodiment, in response to a request to change the amount of driving energy, the electronic control unit 10 changes the amount of driving energy of the drive circuit 11 or 12 on condition that the drive circuit 11 or 12 is in a standby state where the drive circuit 11 or 12 is not executing fuel injection.
• the drive circuit 1 1 or 12 that is executing fuel injection is not caused to change the amount of driving energy at that moment but is caused to accomplish the fuel injection at the pre-changed amount of driving energy. Then, the drive circuit that is not executing fuel injection is caused to change the amount of driving energy. Therefore, in the present embodiment, the amount of driving energy is not changed during fuel injection. Thus, according to the present embodiment, the amount of driving energy may be changed without any deviation of the fuel injection amount.
• the fuel injection system includes two drive circuits; instead, the aspect of the invention may be applied to an internal combustion engine that includes a fuel injection system having three or more drive circuits.
• the drive circuit that is executing fuel injection is caused to accomplish the fuel injection at the pre-changed amount of driving energy, and the drive circuits that are not executing fuel injection each are caused to change the amount of driving energy. By so doing, it is possible to change the amount of driving energy without any deviation of the fuel injection amount.
• the fuel injection system includes the plurality of drive circuits; instead, the aspect of the invention may be applied to an internal combustion engine that includes a fuel injection system having a single drive circuit.
• the injection is allowed to accomplish the fuel injection at the pre-changed amount of driving energy. Then, if the amount of driving energy is changed during a period from completion of fuel injection that is being carried out at the time when a request to change the amount of driving energy is issued to start of the next fuel injection, it is possible to change the amount of driving energy without any deviation of the fuel injection amount.
• the aspect of the invention is applied to a fuel injection device employed in a V-eight diesel engine; instead, the aspect of the invention may also be similarly applied to an internal combustion engine that has different cylinder arrangement or a different number of cylinders or that uses a different fuel.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Fuel-Injection Apparatus (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

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Citations (5)

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• 2010
  • 2010-06-22 JP JP2010141630A patent/JP5204156B2/ja active Active
• 2011
  • 2011-06-14 RU RU2012155497/07A patent/RU2542333C2/ru active
  • 2011-06-14 WO PCT/IB2011/001668 patent/WO2012014034A1/en active Application Filing
  • 2011-06-14 EP EP11743620.4A patent/EP2585702A1/en not_active Ceased
  • 2011-06-14 AU AU2011284466A patent/AU2011284466B2/en not_active Ceased
• 2012
  • 2012-12-14 ZA ZA2012/09532A patent/ZA201209532B/en unknown

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