Classifications

• • 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

Definitions

• This disclosure relates to a control device for an internal combustion engine.
• the control device for an internal combustion engine includes: an angle information detection unit that detects a crank angle, a crank angular velocity, and a crank angular acceleration based on an output signal of the crank angle sensor; an intake pipe gas pressure detection unit that detects the gas pressure in the intake pipe based on an output signal of a gas pressure sensor that detects the gas pressure in the intake pipe; an uncombusted torque calculation unit that estimates an uncombusted torque, which is a torque applied to the crankshaft due to the gas pressure in the cylinder and the reciprocating motion of the piston, using a physical model equation of the crank mechanism based on the gas pressure in the intake pipe, the crank angular velocity, and the crank angular acceleration at each crank angle; an external load torque calculation unit that calculates, for a current combustible angle interval, an external load torque that is a torque applied to the crankshaft from outside the internal combustion engine based on the crank angular acceleration and the torque at the time of uncombustion, at a crank angle near the top dead
• the crank angular acceleration near top dead center fluctuates due to the influence of the abnormal combustion
• the external load torque for the current combustible angle range which is calculated based on the crank angular acceleration, includes the influence of the abnormal combustion. Therefore, if the external load torque for the current combustible angle range is used as the external load torque used to detect the occurrence of abnormal combustion in the current combustible angle range, the occurrence of abnormal combustion cannot be detected accurately.
• the external load torque used for calculation to detect the occurrence of abnormal combustion in the current combustible angle range is calculated by smoothing multiple external load torques calculated in past combustible angle ranges before the abnormal combustion occurred. Since the external load torque for the current combustible angle range, which includes the influence of abnormal combustion, is not used, the occurrence of abnormal combustion can be accurately determined.
• 1 is a schematic configuration diagram of an internal combustion engine and a control device for the internal combustion engine according to a first embodiment
• 1 is a schematic configuration diagram of an internal combustion engine and a control device for the internal combustion engine according to a first embodiment
• 1 is a block diagram of a control device for an internal combustion engine according to a first embodiment.
• 1 is a hardware configuration diagram of a control device for an internal combustion engine according to a first embodiment.
• 4 is a time chart for explaining angle information detection processing according to the first embodiment.
• FIG. 4 is a diagram for explaining a combustible angle interval and top dead center of each cylinder according to the first embodiment.
• 10A and 10B are diagrams illustrating a comparative example in which pre-ignition does not occur according to the first embodiment and an example of the present embodiment.
• FIG. 10A and 10B are diagrams illustrating a comparative example in the case where pre-ignition occurs according to the first embodiment and an example of the present embodiment.
• FIG. 10 is a diagram illustrating a holding process after pre-ignition occurs according to the first embodiment.
• FIG. 5 is a diagram illustrating a holding process after a misfire occurs according to the first embodiment.
• 5A and 5B are diagrams illustrating a determination of erroneous detection of abnormal combustion after the occurrence of a disturbance according to the first embodiment.
• 5 is a diagram illustrating a holding process after abnormal combustion is detected according to the first embodiment.
• FIG. 10A and 10B are diagrams illustrating a process for detecting the occurrence of pre-ignition according to the first embodiment.
• FIG. 4 is a diagram illustrating a process for detecting the occurrence of a misfire according to the first embodiment.
• FIG. 1 A control device 50 for an internal combustion engine 1 according to a first embodiment (hereinafter simply referred to as the control device 50) will be described with reference to the drawings.
• Figures 1 and 2 are schematic configuration diagrams of the internal combustion engine 1 and the control device 50 according to this embodiment
• Figure 3 is a block diagram of the control device 50 according to this embodiment.
• the internal combustion engine 1 and the control device 50 are mounted on a vehicle, and the internal combustion engine 1 serves as a driving force source for the vehicle (wheels).
• the internal combustion engine 1 has cylinders 7 that burn a mixture of air and fuel.
• the internal combustion engine 1 has an intake pipe 23 that supplies air to the cylinders 7, and an exhaust pipe 17 that discharges exhaust gas burned in the cylinders 7.
• the internal combustion engine 1 is a gasoline engine.
• the internal combustion engine 1 has a throttle valve 4 that opens and closes the intake pipe 23.
• the throttle valve 4 is an electronically controlled throttle valve that is driven to open and close by an electric motor controlled by a control device 50.
• the throttle valve 4 is provided with a throttle opening sensor 19 that outputs an electric signal corresponding to the opening of the throttle valve 4.
• the intake pipe 23 upstream of the throttle valve 4 is provided with an air flow sensor 3 that outputs an electrical signal corresponding to the amount of intake air drawn into the intake pipe 23.
• the internal combustion engine 1 is equipped with an exhaust gas recirculation device 20.
• the exhaust gas recirculation device 20 has an EGR flow path 21 that recirculates exhaust gas from the exhaust pipe 17 to the intake manifold 12, and an EGR valve 22 that opens and closes the EGR flow path 21.
• the intake manifold 12 is the portion of the intake pipe 23 downstream of the throttle valve 4.
• the EGR valve 22 is an electronically controlled EGR valve that is opened and closed by an electric motor controlled by the control device 50.
• the exhaust pipe 17 is equipped with an air-fuel ratio sensor 18 that outputs an electrical signal corresponding to the air-fuel ratio of the exhaust gas in the exhaust pipe 17.
• the intake manifold 12 is provided with a gas pressure sensor 8 that outputs an electrical signal corresponding to the pressure inside the intake manifold 12.
• An injector 13 that injects fuel is provided downstream of the intake manifold 12. Note that the injector 13 may also be provided to inject fuel directly into the cylinders 7.
• the internal combustion engine 1 is provided with an atmospheric pressure sensor 33 that outputs an electrical signal corresponding to the atmospheric pressure Patm.
• the internal combustion engine 1 is provided with a water temperature sensor 34 that detects the coolant temperature.
• the top of cylinder 7 is provided with a spark plug that ignites the air-fuel mixture, and an ignition coil 16 that supplies ignition energy to the spark plug. Also provided at the top of cylinder 7 are an intake valve 14 that adjusts the amount of intake air drawn into cylinder 7 from intake pipe 23, and an exhaust valve 15 that adjusts the amount of exhaust gas discharged from the cylinder to exhaust pipe 17.
• the intake valve 14 is provided with an intake variable valve timing mechanism that varies its valve opening and closing timing.
• the exhaust valve 15 is provided with an exhaust variable valve timing mechanism that varies its valve opening and closing timing. Both variable valve timing mechanisms 14 and 15 have electric actuators.
• the internal combustion engine 1 has multiple cylinders 7 (three in this example). Each cylinder 7 has a piston 5 inside. The piston 5 of each cylinder 7 is connected to the crankshaft 2 via a connecting rod 9 and a crank 32. The crankshaft 2 is rotated by the reciprocating motion of the piston 5. The combustion gas pressure generated in each cylinder 7 presses against the top surface of the piston 5, rotating the crankshaft 2 via the connecting rod 9 and the crank 32.
• the crankshaft 2 is connected to a power transmission mechanism that transmits driving force to the wheels.
• the power transmission mechanism is composed of a transmission, a differential gear, etc. Note that a vehicle equipped with the internal combustion engine 1 may also be a hybrid vehicle equipped with a motor-generator within the power transmission mechanism.
• the internal combustion engine 1 is equipped with a signal plate 10 that rotates integrally with the crankshaft 2.
• the signal plate 10 has multiple teeth at multiple predetermined crank angles.
• the signal plate 10 has teeth arranged at 10-degree intervals.
• the teeth of the signal plate 10 have missing teeth.
• the internal combustion engine 1 is equipped with a crank angle sensor 11 that is fixed to the engine block 24 and detects the teeth of the signal plate 10.
• the internal combustion engine 1 is equipped with a camshaft 29 connected to the crankshaft 2 by a chain 28.
• the camshaft 29 drives the intake valves 14 and exhaust valves 15 to open and close.
• the camshaft 29 rotates once for every two rotations of the crankshaft 2.
• the internal combustion engine 1 is equipped with a cam signal plate 31 that rotates integrally with the camshaft 29.
• the cam signal plate 31 has multiple teeth at multiple predetermined camshaft angles.
• the internal combustion engine 1 is equipped with a cam angle sensor 30 that is fixed to the engine block 24 and detects the teeth of the cam signal plate 31.
• the control device 50 detects the crank angle relative to the top dead center of each piston 5 based on two types of output signals from the crank angle sensor 11 and the cam angle sensor 30, and determines the stroke of each cylinder 7.
• the internal combustion engine 1 is a four-stroke engine with an intake stroke, compression stroke, combustion stroke, and exhaust stroke.
• the crank angle sensor 11 and cam angle sensor 30 output electrical signals in response to changes in the distance between each sensor and the teeth due to the rotation of the crankshaft 2.
• the output signal from each angle sensor 11, 30 is a square wave that turns on and off depending on whether the sensor is close to the teeth or far away.
• Each angle sensor 11, 30 is, for example, an electromagnetic pickup type sensor.
• the control device 50 is a control device that controls the internal combustion engine 1.
• the control device 50 includes control units such as an angle information detection unit 51, an intake pipe gas pressure detection unit 52, an uncombusted torque calculation unit 53, an external load torque calculation unit 54, an in-cylinder gas pressure calculation unit 55, an abnormal combustion detection unit 56, a disturbance detection unit 57, an avoidance control unit 58, and a basic control unit 59.
• the control units 51 to 59 of the control device 50 are realized by processing circuits included in the control device 50. Specifically, as shown in FIG.
• the control device 50 includes, as processing circuits, an arithmetic processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 connected to the arithmetic processing device 90 via a signal line such as a bus, an input circuit 92 that inputs external signals to the arithmetic processing device 90, and an output circuit 93 that outputs signals from the arithmetic processing device 90 to the outside.
• an arithmetic processing device 90 such as a CPU (Central Processing Unit)
• storage device 91 connected to the arithmetic processing device 90 via a signal line such as a bus
• an input circuit 92 that inputs external signals to the arithmetic processing device 90
• an output circuit 93 that outputs signals from the arithmetic processing device 90 to the outside.
• the arithmetic processing device 90 may be an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, and various signal processing circuits. Furthermore, multiple arithmetic processing devices 90 of the same type or different types may be provided, with each device sharing the processing load.
• ASIC Application Specific Integrated Circuit
• IC Integrated Circuit
• DSP Digital Signal Processor
• FPGA Field Programmable Gate Array
• various logic circuits and various signal processing circuits.
• multiple arithmetic processing devices 90 of the same type or different types may be provided, with each device sharing the processing load.
• the storage device 91 includes volatile and non-volatile storage devices such as RAM (Random Access Memory), ROM (Read Only Memory), and EEPROM (Electrically Erasable Programmable ROM).
• the input circuit 92 is connected to various sensors and switches and includes A/D converters and the like that input the output signals of these sensors and switches to the arithmetic processing device 90.
• the output circuit 93 is connected to electrical loads and includes drive circuits and the like that output control signals from the arithmetic processing device 90 to these electrical loads.
• Data such as calculated values and detected values, including the crank angular velocity ⁇ d, crank angular acceleration ⁇ d, in-cylinder gas pressure Pcyl, in-cylinder gas pressure Pcyl_unbrn when uncombusted, in-cylinder gas pressure increase ⁇ Pcyl_brn due to combustion, external load torque Tload, and external load torque Tload_cal used for calculation, calculated by the control units 51 to 58, etc., are stored in a rewritable storage device 91, such as a RAM.
• the input circuit 92 is connected to the crank angle sensor 11, cam angle sensor 30, water temperature sensor 34, air flow sensor 3, throttle opening sensor 19, gas pressure sensor 8, atmospheric pressure sensor 33, air-fuel ratio sensor 18, and accelerator position sensor 26.
• the output circuit 93 is connected to the throttle valve 4 (electric motor), EGR valve 22 (electric motor), injector 13, ignition coil 16, intake variable valve timing mechanism 14, and exhaust variable valve timing mechanism 15.
• Various sensors, switches, and actuators are also connected to the control device 50. Based on the output signals of the various sensors, the control device 50 detects the operating conditions of the internal combustion engine 1, such as the intake air volume, pressure in the intake manifold, atmospheric pressure Patm, air-fuel ratio, and accelerator opening.
• Basic control unit 59 As a basic control, the basic control unit 59 calculates the fuel injection amount, ignition timing, etc. based on the input output signals of various sensors, etc., and controls the injector 13, the ignition coil 16, etc. The basic control unit 59 calculates the output torque of the internal combustion engine 1 requested by the driver based on the output signal of the accelerator position sensor 26, etc., and controls the throttle valve 4, etc., so as to obtain an intake air amount that realizes the requested output torque. Specifically, the basic control unit 59 calculates a target throttle opening, and controls the drive of the electric motor of the throttle valve 4 so that the throttle opening detected based on the output signal of the throttle opening sensor 19 approaches the target throttle opening.
• the basic control unit 59 also calculates a target opening of the EGR valve 22 based on the input output signals of various sensors, etc., and controls the drive of the electric motor of the EGR valve 22.
• the basic control unit 59 calculates the target opening/closing timing of the intake valve and the target opening/closing timing of the exhaust valve based on the output signals of various sensors input thereto, and controls the operation of the intake and exhaust variable valve timing mechanisms 14, 15 based on the respective target opening/closing timings.
• Intake pipe gas pressure detection unit 52 The intake pipe gas pressure detection unit 52 detects the gas pressure Pin in the intake pipe based on the output signal of the gas pressure sensor 8 that detects the gas pressure in the intake pipe.
• Angle information detection unit 51 detects the crank angle ⁇ d based on the output signal of the crank angle sensor 11, and calculates a crank angular velocity ⁇ d, which is the time rate of change of the detected crank angle ⁇ d, and a crank angular acceleration ⁇ d, which is the time rate of change of the crank angular velocity ⁇ d.
• the crank angular velocity ⁇ d corresponds to the rotation speed.
• External load torque calculation unit 54 calculates, for each combustible angle interval, an external load torque Tload, which is a torque applied to the crankshaft from outside the internal combustion engine, based on the crank angular acceleration ⁇ d and the torque Tcrk_unbrn during uncombusted combustion at a crank angle ⁇ d_tdc near the top dead center of the piston in the combustion stroke.
• the external load torque calculation unit 54 smoothes multiple external load torques Tload calculated in past combustible angle intervals to calculate an external load torque Tload_cal for calculation to be used in the current combustible angle interval.
• Figure 8 shows a comparative example and an example of this embodiment in which pre-ignition occurs near top dead center in the current burnable angle interval.
• the external load torque Tload of the current burnable angle interval is set as the external load torque Tload_cal for calculation used in the current burnable angle interval
• the smoothed value of multiple external load torques Tload of past burnable angle intervals is set as the external load torque Tload_cal for calculation.
• the external load torque Tload of the current burnable angle interval calculated near top dead center includes the component of the actual torque Tcrkd that suddenly rose due to the occurrence of pre-ignition as a component of the external load torque Toad.
• the internal combustion engine 1 has multiple cylinders (three in this example).
• the external load torque calculation unit 54 smoothes multiple external load torques Tload_i calculated in past burnable angle intervals for the same cylinder as the target cylinder i corresponding to the current burnable angle interval, and calculates the external load torque Tload_cal_i for calculation to be used in the current burnable angle interval of the target cylinder i.
• the external load torque Tload is estimated based on the unburned torque Tcrk_unbrn_tdc, which is estimated from the gas pressure inside the cylinder and the reciprocating motion of the piston, and the actual torque Tcrkd_tdc.
• the unburned torque Tcrk_unbrn_tdc is a value calculated under ideal conditions where there is no variation between cylinders
• the actual torque Tcrkd_tdc is a value that reflects the influence of variation between cylinders near top dead center of the target cylinder i.
• the external load torque Tload_i calculated from both includes information on the variation between cylinders that affects the combustible angle range of the target cylinder i.
• the external load torque Tload_cal_i for calculation can include information on variations between cylinders that affect the burnable angle range of the target cylinder i.
• first-order lag filtering is used as the smoothing process.
• the external load torque calculation unit 54 calculates the external load torque Tload_cal_i(j_i-1) for calculation used in the current combustible angle interval (j_i-1) of the target cylinder i by adding a value obtained by multiplying the external load torque Tload_cal_i(j_i-1) for calculation calculated in the previous combustible angle interval (j_i-1) of the target cylinder i by a filter coefficient Kflt to a value obtained by multiplying the external load torque Tload_i(j_i-1) calculated in the previous combustible angle interval (j_i-1) of the target cylinder i by (1 - filter coefficient Kflt).
• the filter coefficient Kflt is set to a value smaller than 1.
• the external load torque Tload_cal_i used for calculation is stored in a storage device such as RAM in association with the cylinder number corresponding to the combustible angle range and the history number j_i of the combustible angle range for each cylinder number.
• the external load torque calculation unit 54 calculates the average value of the external load torques Tload_i(j_i-1), Tload_i(j_i-2), Tload_i(j_i-3), and Tload_i(j_i-4) calculated in the previous, two, three, and four previous combustible angle intervals (j_i-1), (j_i-2), (j_i-3), and (j_i-4) of the target cylinder i as the external load torque Tload_cal_i(j_i) for calculation to be used in the current combustible angle interval (j_i-1) of the target cylinder i.
• the number of cycles to be averaged may be any number equal to or greater than 1. Alternatively, a weighted moving average may be used.
• the abnormal combustion detection unit 56 described later detects the occurrence of abnormal combustion due to gas pressure based on one or both of the increase in cylinder gas pressure ⁇ Pcyl_brn due to combustion and the cylinder gas pressure Pcyl
• the external load torque calculation unit 54 performs a holding process to calculate the external load torque Tload_cal for calculation to be used in the current burnable angle interval based on the external load torque Tload calculated in the previous burnable angle interval before the abnormality occurrence burnable angle interval, during the burnable angle interval of the holding cycle number including the abnormality occurrence burnable angle interval, which is the burnable angle interval in which the occurrence of abnormal combustion was detected.
• the external load torque Tload and external load torque deviation ⁇ Tload fluctuate for a while after pre-ignition occurs, and it can be seen that calculation accuracy can be maintained by performing a process to hold the external load torque Tload_cal used for calculation during the burnable angle interval of the number of holding cycles.
• Figure 10 shows behavior after a misfire occurs. Multiple samples are overlaid in Figure 10.
• the horizontal axis represents the number of combustible angle intervals (number of combustion cycles), and the vertical axis represents the maximum increase in cylinder gas pressure due to combustion ⁇ Pcyl_brnmax, which is used to determine misfire, as described below; the external load torque Tload calculated near top dead center in each combustible angle interval (combustion cycle); and the external load torque deviation ⁇ Tload, which represents the fluctuation in the external load torque Tload for each cylinder.
• the external load torque Tload and external load torque deviation ⁇ Tload fluctuate for a while after a misfire occurs, and it can be seen that calculation accuracy can be maintained by holding the external load torque Tload_cal for calculation during the combustible angle interval of the number of holding cycles.
• the number of holding cycles for misfire can be made fewer than the number of holding cycles for pre-ignition.
• the external load torque calculation unit 54 calculates the external load torque Tload_cal_i(j_i) for calculation to be used in the current combustible angle interval (j_i-1) of the target cylinder i by adding a value obtained by multiplying the external load torque Tload_cal_i(j_i-1) for calculation calculated in the previous combustible angle interval (j_i-1) of the target cylinder i by the filter coefficient Kflt to a value obtained by multiplying the external load torque Tload_i(j_i_bf) calculated in the combustible angle interval (j_i_bf) of the target cylinder i immediately before the abnormality-occurring
• the external load torque Tload_i(j_i_bf) calculated in the combustible angle interval (j_i_bf) of the target cylinder i immediately before the abnormality-occurring combustible angle interval continues to be input to the first-order lag filter processing.
• the external load torque Tload fluctuates significantly and continues to fluctuate for a while afterwards.
• the external load torque Tload_cal for calculation for each cylinder is calculated using the previous external load torque Tload calculated for the same cylinder before pre-ignition occurred. Therefore, the external load torque Tload_cal for calculation can be calculated without being affected by fluctuations in the external load torque Tload due to the occurrence of pre-ignition. Furthermore, because the external load torque Tload_cal for calculation for each cylinder is calculated using the previous external load torque Tload for the same cylinder before pre-ignition occurred, information on variations between cylinders can be retained.
• the external load torque calculation unit 54 may set the external load torque Tload_cal_i(j_i) for calculation of the target cylinder i to the external load torque Tload_cal_i(j_i-1) for calculation calculated in the previous combustible angle interval (j_i-1) of the target cylinder i, and may hold it at the external load torque Tload_cal_i(j_i_bf) for calculation of the target cylinder i calculated in the combustible angle interval (j_i_bf) of the target cylinder i immediately before the abnormality occurrence combustible angle interval, as shown in the following equation.
• the abnormal combustion detection unit 56 is configured to detect the occurrence of abnormal combustion using a detection method other than the method of detecting the occurrence of abnormal combustion based on one or both of the increase in cylinder gas pressure ⁇ Pcyl_brn due to combustion and the cylinder gas pressure Pcy.
• the external load torque Tload_cal used for calculation is held at the external load torque Tload calculated in the previous burnable angle range prior to the disturbance-occurring burnable angle range due to the occurrence of the disturbance factor, just as in the case of the gas pressure detection method.
• the external load torque Tload_cal used for calculation is calculated by smoothing multiple external load torques Tload calculated in past combustible angle intervals. Therefore, after the actual external load torque fluctuates, for at least the number of combustible angle intervals equal to the total number of cylinders (four in this example), the fluctuations in the actual external load torque are reflected in the increase in gas pressure torque due to combustion ⁇ Tgas_brn and the in-cylinder gas pressure Pcyl, causing the in-cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value to increase, resulting in a false detection of pre-ignition. Note that, as described below, if the occurrence of a disturbance factor can be detected with a delay or without omission, false detection can be prevented by stopping detection of the occurrence of abnormal combustion after the occurrence of the disturbance factor is detected.
• Disturbance detection unit 57 detects the occurrence of a disturbance factor that changes the external load torque Tload based on at least one of a change in vehicle speed, a change in the operating state of the air conditioner, a change in the amount of power generated by the alternator, a shift in the transmission, recovery from a fuel cut in the internal combustion engine, and a change in the number of fuel injections in each combustible angle interval.
• the disturbance detection unit 57 detects the occurrence of a disturbance factor related to a change in vehicle speed when the absolute value of the amount of change in vehicle speed per determination period is equal to or greater than a determination value. For example, when driving on rough roads, the wheels may lift off the road surface, and a sudden change in running resistance due to this lifting can be detected from the amount of change in vehicle speed. A sudden change in running resistance changes the external load torque Tload, which becomes a disturbance factor.
• the disturbance detection unit 57 detects the occurrence of a disturbance factor related to a change in the operating state of the air conditioner when the absolute value of the change in the load torque of the air conditioner compressor per judgment period is equal to or greater than the judgment value.
• the load torque of the air conditioner is estimated based on the compressor rotation speed, which is proportional to the rotation speed of the internal combustion engine, and the refrigerant pressure increased by the compressor. Because the compressor is driven by the rotational driving force of the crankshaft, changes in the compressor load torque cause changes in the external load torque Tload, which becomes a disturbance factor.
• the disturbance detection unit 57 detects the occurrence of a disturbance factor related to changes in the amount of power generated by the alternator when the absolute value of the change in the alternator's power generation torque per determination period is equal to or greater than the determination value.
• the alternator's power generation torque is estimated based on the alternator's rotational speed, which is proportional to the rotational speed of the internal combustion engine, and the generated current. Because the alternator is driven by the rotational driving force of the crankshaft, changes in the alternator's power generation torque cause changes in the external load torque Tload, which becomes a disturbance factor.
• the disturbance detection unit 57 detects the occurrence of disturbance factors related to transmission shifting when the transmission gear position changes.
• the transmission is installed between the crankshaft and the wheels. When the gear position changes, torque fluctuations are transmitted to the crankshaft, causing a change in the external load torque Tload, which becomes a disturbance factor.
• the disturbance detection unit 57 detects the occurrence of a disturbance factor related to the internal combustion engine recovering from a fuel cut.
• the generated torque changes, which becomes a disturbance factor.
• the disturbance detection unit 57 detects the occurrence of disturbance factors related to changes in the number of fuel injections when the number of fuel injections in each combustible angle interval changes. For example, if the number of injections changes, such as when fuel is injected once during the intake stroke, twice during the exhaust stroke and intake stroke, or three times during the exhaust stroke, intake stroke, and compression stroke, the combustion state and generated torque change, which becomes a disturbance factor.
• Cylinder gas pressure calculation unit 55 The cylinder gas pressure calculation unit 55 calculates, at each crank angle ⁇ d, one or both of the increase in cylinder gas pressure ⁇ Pcyl_brn due to combustion and the cylinder gas pressure Pcyl based on the crank angular acceleration ⁇ d, the torque Tcrk_unbrn when uncombusted, and the external load torque Tload_cal for calculating the current combustible angle interval corresponding to the crank angle ⁇ d.
• the cylinder gas pressure calculation unit 55 calculates the increase in gas pressure torque due to combustion, ⁇ Tgas_brn, of the gas pressure torque applied to the crankshaft by the cylinder gas pressure, at each crank angle ⁇ d based on the crank angular acceleration ⁇ d.
• the cylinder gas pressure calculation unit 55 also calculates the increase in cylinder gas pressure due to combustion, ⁇ Pcyl_brn, at each crank angle ⁇ d based on the increase in gas pressure torque due to combustion, ⁇ Tgas_brn, and the crank angle ⁇ d.
• the cylinder internal gas pressure calculation unit 55 calculates the actual torque Tcrkd applied to the crankshaft at each crank angle ⁇ d based on the crank angular acceleration ⁇ d. Specifically, the cylinder internal gas pressure calculation unit 55 calculates the actual torque Tcrkd by multiplying the crank angular acceleration ⁇ d by the moment of inertia Icrk of the crankshaft system at each crank angle ⁇ d, as shown in the following equation.
• the cylinder gas pressure calculation unit 55 calculates the gas pressure torque increase ⁇ Tgas_brn due to combustion at each crank angle ⁇ d based on the crank angular acceleration ⁇ d, the torque Tcrk_unbrn in the uncombusted state, and the external load torque Tload_cal for calculating the current combustible angle interval corresponding to the crank angle ⁇ d. Specifically, the cylinder gas pressure calculation unit 55 calculates the gas pressure torque increase ⁇ Tgas_brn due to combustion by subtracting the torque Tcrk_unbrn in the uncombusted state from the actual torque Tcrkd and adding the external load torque Tload_cal for calculation, as shown in the following equation. In this embodiment, the external load torque Tload_cal_i for calculation calculated for the target cylinder i corresponding to the current combustible angle interval corresponding to the crank angle ⁇ d is used as the external load torque Tload_cal for calculation.
• the cylinder gas pressure calculation unit 55 calculates the increase in cylinder gas pressure due to combustion ⁇ Pcyl_brn at each crank angle ⁇ d based on the increase in gas pressure torque due to combustion ⁇ Tgas_brn. Specifically, the cylinder gas pressure calculation unit 55 calculates the increase in cylinder gas pressure due to combustion ⁇ Pcyl_brn using the following equation:
• the conversion coefficient R_brn is the conversion coefficient for the combustion cylinder among the conversion coefficients R_i for each cylinder i in equation (4).
• the uncombusted torque calculation unit 53 may calculate the average value of ⁇ Pcyl_brn calculated at crank angles before and after top dead center as ⁇ Pcyl_brn at top dead center.
• the cylinder gas pressure calculation unit 55 calculates the cylinder gas pressure Pcyl by adding the uncombusted cylinder gas pressure Pcyl_unbrn and the increase in cylinder gas pressure ⁇ Pcyl_brn due to combustion at each crank angle ⁇ d, as shown in the following equation.
• the cylinder gas pressure calculation unit 55 stores the calculated values, such as the actual torque Tcrkd calculated at each crank angle ⁇ d, the increase in gas pressure torque due to combustion ⁇ Tgas_brn, the increase in cylinder gas pressure due to combustion ⁇ Pcyl_brn, and the cylinder gas pressure Pcyl, along with the cylinder number corresponding to the combustible angle range, the corresponding angle identification number n, and angle information such as the crank angle ⁇ d, in a storage device 91 such as RAM.
• the abnormal combustion detection unit 56 determines the maximum value ⁇ Pcyl_brnmax of the increase in cylinder gas pressure due to combustion ⁇ Pcyl_brn calculated at each crank angle ⁇ d in the current combustible angle range. The abnormal combustion detection unit 56 then determines whether the maximum value ⁇ Pcyl_brnmax of the increase in cylinder gas pressure due to combustion is smaller than a misfire determination value, and if it is smaller than the misfire determination value, determines that a misfire has occurred in the target cylinder corresponding to the current combustible angle range.
• the misfire determination value may be set according to the rotational speed and load.
• the crank angle ⁇ d corresponding to the maximum value ⁇ Pcyl_brnmax of the increase in cylinder gas pressure due to combustion may also be taken into consideration when determining whether a misfire has occurred.
• the abnormal combustion detection unit 56 calculates the in-cylinder gas pressure Pcyl at the crank angle ⁇ d corresponding to the maximum value ⁇ Pcyl_brnmax of the increase in in-cylinder gas pressure due to combustion as the in-cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value. Then, the abnormal combustion detection unit 56 determines whether the in-cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value is greater than a pre-ignition determination value, and if it is greater than the pre-ignition determination value, determines that pre-ignition has occurred in the target cylinder corresponding to the current combustible angle interval.
• the pre-ignition determination value may be set according to the rotational speed and load.
• the crank angle ⁇ d corresponding to the maximum value ⁇ Pcyl_brnmax of the increase in in-cylinder gas pressure due to combustion may also be taken into consideration when determining whether pre-ignition has occurred.
• FIG. 13 shows examples of pre-ignition determination in a comparative example and in this embodiment.
• the determination results of samples of multiple combustible angle intervals when pre-ignition has occurred and when it has not occurred are overlaid.
• the horizontal axis represents the crank angle ⁇ d corresponding to the maximum value ⁇ Pcyl_brnmax of the increase in cylinder gas pressure due to combustion, and the vertical axis represents the cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value of the cylinder gas pressure Pcyl at that crank angle ⁇ d.
• the external load torque Tload_cal for calculation used in the current combustible angle interval is set to the external load torque Tload for the current combustible angle interval.
• the external load torque Tload_cal for calculation is set to a smoothed value of multiple external load torques Tload for past combustible angle intervals.
• the in-cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value for all samples was smaller than the pre-ignition determination value, and the occurrence of pre-ignition was not detected with high accuracy.
• the component of the actual torque Tcrkd that suddenly rises due to the occurrence of pre-ignition is included as a component of the external load torque Toad, and when calculating the increase in cylinder gas pressure ⁇ Pcyl_brn due to combustion and the cylinder gas pressure Pcyl, the characteristics of the sudden rise in torque and gas pressure due to the occurrence of pre-ignition are lost.
• the in-cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value is greater than the pre-ignition determination value, and in samples where pre-ignition does not occur, the in-cylinder gas pressure Pcyl ⁇ max corresponding to the maximum value is less than the pre-ignition determination value, and the occurrence of pre-ignition is detected with high accuracy.
• the smoothed value of the past external load torque Tload before the occurrence of abnormal combustion is used, so the component of the actual torque Tcrkd that suddenly rises due to the occurrence of pre-ignition is not canceled out, and the increase in cylinder gas pressure due to combustion ⁇ Pcyl_brn and the cylinder gas pressure Pcyl reflect the characteristics of the torque and cylinder gas pressure that suddenly rise due to the occurrence of pre-ignition.
• ⁇ Example of misfire detection> 14 shows an example of misfire determination according to this embodiment.
• determination results for samples of multiple combustible angle intervals when misfire occurs and when it does not occur are overlaid.
• the horizontal axis represents the crank angle ⁇ d corresponding to the maximum increase ⁇ Pcyl_brnmax in cylinder gas pressure due to combustion, and the vertical axis represents the maximum increase ⁇ Pcyl_brnmax in cylinder gas pressure due to combustion at that crank angle ⁇ d.
• the maximum increase in cylinder gas pressure due to combustion, ⁇ Pcyl_brnmax is smaller than the misfire determination value, while in samples where a misfire does not occur, the maximum increase in cylinder gas pressure due to combustion, ⁇ Pcyl_brnmax, is greater than the misfire determination value, allowing for accurate detection of misfire occurrence.

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• 2024
  • 2024-03-21 JP JP2026508137A patent/JPWO2025197019A1/ja active Pending
  • 2024-03-21 WO PCT/JP2024/011029 patent/WO2025197019A1/ja active Pending

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