Vehicle control device

Abstract

To provide a control device of a vehicle capable of accurately determining misfire abnormality.SOLUTION: A control device of a vehicle having a clutch on a power transmission path between an engine and a transmission includes a count section for counting a misfire counter indicating a misfire frequency of the engine when a rotational fluctuation amount of the engine is larger than a threshold, an execution section for executing fail-safe processing for disengaging the clutch when the misfire counter is larger than a first determination value, a determination section for determining misfire abnormality of the engine when the misfire counter is larger than a second determination value that is larger than the first determination value, and a setting section for setting the threshold during execution of the fail-safe processing to be higher than the threshold during stop of the fail-safe processing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] BACKGROUND ART In a vehicle equipped with a clutch on a power transmission path between an engine and a transmission, a technique for determining whether an engine misfire has occurred based on the amount of engine rotation fluctuation is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-024369 Summary of the Invention [Problem to be solved by the invention]

[0004] From the perspective of protecting components, it is conceivable to execute a fail-safe process to disengage the clutch before a misfire is determined. By disengaging the clutch, the effect of engine rotation fluctuations on the transmission, which is located downstream of the clutch, can be suppressed. However, the amount of engine rotation fluctuations when a misfire occurs differs between when the fail-safe process, in which the clutch is disengaged, is being executed and when the fail-safe process is stopped. This may result in inaccurate determination of a misfire.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle control device that can accurately determine whether a misfire has occurred. [Means for solving the problem]

[0006] The above object can be achieved by a control device for a vehicle having a clutch on a power transmission path between an engine and a transmission, the control device comprising: a counting unit that counts a misfire counter that indicates the number of misfires of the engine when the rotational fluctuation amount of the engine is greater than a threshold value; an execution unit that executes a failsafe process to release the clutch when the misfire counter is greater than a first judgment value; a judgment unit that judges a misfire abnormality of the engine when the misfire counter is greater than a second judgment value that is greater than the first judgment value; and a setting unit that sets the threshold value during execution of the failsafe process to a value higher than the threshold value during stoppage of the failsafe process.

[0007] The vehicle may include a first motor provided between the engine and the clutch, a second motor arranged on a power transmission path different from the power transmission path, and a battery that is charged with power generated by the first motor and supplies power to the second motor, and the execution unit may, as the fail-safe processing, cause the engine to operate the first motor in a regenerative manner to charge the battery while causing the vehicle to run using the second motor.

[0008] The vehicle may include a motor provided on the power transmission path between the clutch and the transmission, and the execution unit may run the vehicle using the motor as the fail-safe process. [Effects of the Invention]

[0009] According to the present invention, a vehicle control device that can accurately determine misfire abnormalities can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 2 is a flowchart showing an example of misfire counter update control executed by the ECU. [Figure 3]FIG. 3 is a flowchart showing an example of misfire abnormality determination control executed by the ECU. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Hybrid vehicle configuration] FIG. 1 is a schematic diagram of a hybrid vehicle 10. The hybrid vehicle 10 is equipped with an engine 200, a front motor 220, and a rear motor 270 as driving power sources. The engine 200 is a gasoline engine or a diesel engine. The front motor 220 and the rear motor 270 are driven to rotate by receiving electric power from a battery 310 (described later) via power converters 300 and 320, respectively. The front motor 220 generates electric power by regenerative operation using the power of the engine 200. The rear motor 270 drives the hybrid vehicle 10, as will be described in more detail later. The front motor 220 and the rear motor 270 are arranged on different power transmission paths.

[0012] A K0 clutch 210 is provided between the engine 200 and the front motor 220. The K0 clutch 210 engages, slips, and disengages the engine 200 and the front motor 220. A WSC (Wet Start Clutch) clutch 230 is provided between the front motor 220 and the transmission 240. The WSC clutch 230 engages, slips, and disengages the front motor 220 and the transmission 240. The K0 clutch 210 and the WSC clutch 230 are switched between engagement, slip, and disengagement in accordance with hydraulic pressure supplied from a hydraulic control device (not shown).

[0013] The transmission 240 is a transmission that switches between gear ratios with different stages, such as five forward speeds and one reverse speed. The gear ratios are switched according to, for example, the vehicle speed or the accelerator pedal position. The WSC clutch 230 is provided separately from the transmission 240, but some of the friction engagement elements that are engaged in each gear of the transmission 240 may be used. Note that a lock-up clutch provided in a torque converter may be used instead of the WSC clutch 230.

[0014] The output shaft of transmission 240 is connected to drive wheels 251 and 252, which are front wheels, via propeller shaft 245, differential 250, right drive shaft 261, and left drive shaft 262. The output shaft of rear motor 270 is connected to drive wheels 253 and 254, which are rear wheels, via propeller shaft 275, differential 280, right drive shaft 291, and left drive shaft 292.

[0015] Each of the power conversion devices 300 and 320 includes an inverter and a converter, and converts DC power from the battery 310 into AC current and outputs it to the front motor 220 and the rear motor 270, respectively. This allows the front motor 220 and the rear motor 270 to be driven. Furthermore, the power conversion devices 300 and 320 convert AC power generated by the front motor 220 and the rear motor 270 into DC current and output it to the battery 310, thereby charging the battery 310. The battery 310 is a rechargeable secondary battery such as a nickel-metal hydride battery or a lithium-ion battery.

[0016] The ECU (Electronic Control Unit) 100 is an electronic control unit that includes a processing circuit that performs various types of calculations related to the driving control of the hybrid vehicle 10, and a memory that stores control programs and data. The ECU 100 is an example of a vehicle control device, and functionally realizes a counting unit, an execution unit, a determination unit, and a setting unit, which will be described in detail later. The ECU 100 is electrically connected to an ignition switch 510, a crank angle sensor 520, and an SOC sensor 530.

[0017] Ignition switch 510 detects the on / off state of the ignition. Crank angle sensor 520 detects the rotation speed of the crankshaft of engine 200. SOC sensor 530 detects the remaining capacity (SOC: State Of Charge) of battery 310. ECU 100 may obtain the remaining capacity of battery 310 by estimating it using a known method without using an SOC sensor.

[0018] FIG. 2 is a flowchart showing an example of misfire counter update control executed by ECU 100. The flowchart shown in FIG. 2 is continuously repeated while the ignition is on. ECU 100 determines whether the magnitude of the rotational fluctuation amount of engine 200 is greater than a threshold value (step S1). The rotational fluctuation amount is calculated, for example, as follows, based on the detection value of crank angle sensor 520. The rotational fluctuation amount is the difference between the rotational speeds at a predetermined angle interval that includes only one compression top dead center, and the value of the cylinder whose compression top dead center occurs first out of a pair of cylinders whose compression top dead center occurrence timings are adjacent in chronological order, and the value of the cylinder whose compression top dead center occurs last. If no misfire occurs, the rotational fluctuation amount is a value close to zero. If a misfire occurs, the rotational fluctuation amount is a large value.

[0019] If the answer is Yes in step S1, the ECU 100 increments the misfire counter by "1" (step S2). If the answer is No in step S1, the ECU 100 resets the misfire counter to "0" (step S3). In this way, the ECU 100 updates the value of the misfire counter, which indicates the number of misfires that have occurred. Steps S2 and S3 are an example of processing executed by the counting unit.

[0020] 3 is a flowchart showing an example of misfire abnormality determination control executed by the ECU 100. The flowchart shown in FIG. 3 is continuously repeated while the ignition is on. The ECU 100 determines whether the misfire counter is greater than a first determination value (step S11). If the result in step S11 is Yes, the ECU 100 turns on a failsafe execution flag (step S12) and executes failsafe processing (step S13).

[0021] As a fail-safe process, ECU 100 performs running using rear motor 270 while disengaging WSC clutch 230, and causes engine 200 to perform regenerative operation of front motor 220. By disengaging WSC clutch 230, the effects of rotation fluctuations due to misfire in engine 200 can be suppressed from being transmitted to transmission 240 and propeller shaft 245, thereby protecting components such as transmission 240. Furthermore, running of hybrid vehicle 10 can be ensured by rear motor 270. Furthermore, regenerative operation of front motor 220 can charge battery 310. As a result, the rear motor 270 can be driven by power charged in battery 310, allowing hybrid vehicle 10 to continue running. Step S13 is an example of a process executed by the execution unit. Front motor 220 is an example of a first motor, and rear motor 270 is an example of a second motor.

[0022] If step S11 is No or after step S13 is executed, the ECU 100 determines whether the fail-safe execution flag is ON (step S14). If step S14 is No, that is, if the fail-safe processing is stopped and the WSC clutch 230 is engaged, the ECU 100 sets the threshold to a value α (step S15). If step S14 is Yes, that is, if the fail-safe processing is being executed and the WSC clutch 230 is released, the ECU 100 sets the threshold to a value β (step S16). The value β is greater than the value α. The values ​​α and β will be described in detail later. Steps S15 and S16 are an example of processing executed by the setting unit.

[0023] Next, ECU 100 determines whether the misfire counter is greater than a second determination value (step S17). The second determination value is a value greater than the first determination value described above. If the result of step S17 is No, ECU 100 determines that the misfire in engine 200 is within a normal range and determines that combustion is normal (step S18). If the result of step S17 is Yes, ECU 100 determines that the misfire in engine 200 is beyond the normal range and determines that a misfire abnormality has occurred (step S19). For example, when a misfire abnormality determination is made, ECU 100 may turn on a Malfunction Indicator Light (MIL) to notify the driver that a misfire abnormality has occurred in engine 200. Step S19 is an example of processing executed by the determination unit.

[0024] As described above, since the second determination value is greater than the first determination value, the fail-safe process is executed (step S13) before the misfire abnormality determination (step S19) is made in the engine 200. Therefore, the execution of the fail-safe process takes priority over the misfire abnormality determination, and the release of the WSC clutch 230 is given priority, thereby enabling the protection of components such as the transmission 240.

[0025] Furthermore, the threshold value when the fail-safe process is being executed is set to a value β that is higher than the value α that is the threshold value when the fail-safe process is not being executed (step S16). When the WSC clutch 230 is engaged, the engine 200 and the transmission 240 are connected, so the amount of rotational fluctuation due to misfire is small. In contrast, when the WSC clutch 230 is disengaged, the engine 200 and the transmission 240 are disconnected, so the amount of rotational fluctuation due to misfire increases. By switching the threshold value in this way, the misfire counter can be counted accurately regardless of whether the fail-safe process is being executed, and this allows for accurate determination of a misfire abnormality.

[0026] In this embodiment, the hybrid vehicle is controlled by a single ECU 100. However, the present invention is not limited to this. For example, the above-described control may be performed by a plurality of ECUs, such as an engine ECU that controls the engine 200, a front motor ECU that controls the front motor 220, a rear motor ECU that controls the rear motor 270, a clutch ECU that controls the WSC clutch 230, and a battery ECU that controls the battery 310.

[0027] In the above embodiment, the engine 200 and the front motor 220 drive the front wheels, and the rear motor 270 drives the rear wheels, but this is not limiting. For example, the engine and the first motor may drive the rear wheels, and the second motor may drive the front wheels.

[0028] In the above embodiment, the hybrid vehicle 10 is described as having a front motor 220 and a rear motor 270, but the present invention is not limited to this. For example, the hybrid vehicle may not be provided with a rear motor 270. In this case, as a fail-safe process, the K0 clutch 210 between the engine 200 and the front motor 220 may be disengaged, and the front motor 220 may continue to drive the vehicle via the WSC clutch 230. This allows the hybrid vehicle, which does not have a rear motor 270, to continue to drive the vehicle as a fail-safe process. Note that in this case, the hybrid vehicle is not limited to one in which the front wheels are driven by the engine 200 and the front motor 220, but may also be one in which the rear wheels are driven by an engine and a motor.

[0029] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0030] 10 Hybrid vehicles 100 ECU (vehicle control unit, counting unit, execution unit, judgment unit, setting unit) 200 Engine 210 K0 clutch 220 Front motor (first motor) 230 WSC clutch 240 transmission 270 Rear motor (second motor) 300, 320 Power conversion device 310 Battery

Claims

[Claim 1] A control device for a vehicle equipped with a clutch on a power transmission path between a four-cylinder engine and a transmission, a counting unit that counts a misfire counter indicating the number of misfires of the engine when a rotation fluctuation amount of the engine is greater than a threshold value; an execution unit that executes a fail-safe process to release the clutch when the misfire counter is greater than a first determination value; a determination unit that determines that a misfire abnormality has occurred in the engine when the misfire counter is greater than a second determination value that is greater than the first determination value; a setting unit that sets the threshold value during execution of the fail-safe process to a value higher than the threshold value during suspension of the fail-safe process, the vehicle includes a first motor provided between the engine and the clutch, a second motor disposed on a power transmission path different from the power transmission path, and a battery that is charged with power generated by the first motor and supplies power to the second motor; the execution unit causes the engine to perform regenerative operation of the first motor to charge the battery while causing the vehicle to run using the second motor as the fail-safe processing; the rotational fluctuation amount is a difference between a rotational speed value at a predetermined angular interval including only one compression top dead center in a pair of cylinders adjacent in time series in which the compression top dead center occurs first and a rotational speed value at a cylinder whose compression top dead center occurs later, the clutch is provided between the first motor and the transmission on the power transmission path between the engine and the transmission, A vehicle control device that, when it is determined that a misfire abnormality has occurred in the engine, lights up an MIL to notify the driver that a misfire abnormality has occurred in the engine.

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