Vehicle control device

Abstract

To provide a control device for a vehicle capable of suppressing deterioration of accuracy of a stop position of an internal combustion engine.SOLUTION: A control device is for a vehicle including an internal combustion engine as a travelling power source. The control device for the vehicle includes: a control section executing stop position control of the internal combustion engine by temporarily increasing and then, reducing a throttle opening during inertia rotation in which combustion is stopped in automatic stop of the internal combustion engine; a calculation section calculating the number of filled cylinders filled with intake air in the stop position control; and a regulating section maintaining increase timing of the throttle opening in the stop position control when the number of filled cylinders corresponds to a target number, advancing the increase timing when the number of filled cylinders is smaller than the target number, compared to when the number of filled cylinders corresponds to the target number, and delaying the increase timing when the number of filled cylinders is larger than the target number, compared to when the number of filled cylinders corresponds to the target number.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] There is known a technique for controlling the stop position of an internal combustion engine by temporarily increasing and then decreasing the throttle opening during inertial rotation when combustion has stopped during automatic stopping of the internal combustion engine (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-147276 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned stop position control, due to variations in the control accuracy of the throttle opening and deterioration of the throttle valve over time, it may not be possible to fill the desired cylinder with only the desired amount of intake air, which may result in a decrease in the accuracy of the stop position of the internal combustion engine.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a vehicle control device that suppresses a decrease in the accuracy of the stop position of an internal combustion engine. [Means for solving the problem]

[0006] The object of the present invention is to provide a control device for a vehicle having an internal combustion engine as a driving power source, comprising: a control unit which executes a stop position control of the internal combustion engine by temporarily increasing and then decreasing a throttle opening during inertial rotation in which combustion has stopped upon automatic stopping of the internal combustion engine; a calculation unit which calculates the number of cylinders filled with intake air during the stop position control; and a calculation unit which, when the number of cylinders filled with intake air matches a target number, reduces the throttle opening during the stop position control. This is the timing when the increase begins.This can be achieved by a vehicle control device that includes an adjustment unit that maintains the increase timing, and when the number of cylinders filled is less than the target number, advances the increase timing compared to when the number of cylinders filled matches the target number, and when the number of cylinders filled is greater than the target number, delays the increase timing compared to when the number of cylinders filled matches the target number. Effect of the Invention

[0007] According to the present invention, it is possible to provide a vehicle control device in which a decrease in accuracy of the stop position of an internal combustion engine is suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Diagram 2] FIG. 2 is a schematic diagram of the engine. [Diagram 3] FIG. 3 is a timing chart showing an example of the stop position control. [Figure 4] FIG. 4 is a flowchart showing an example of throttle opening increase timing adjustment control executed by the ECU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [General configuration of hybrid vehicle] FIG. 1 is a schematic diagram of a hybrid vehicle 1. In the hybrid vehicle 1, a K0 clutch 14, a motor 15, a torque converter 18, and a transmission 19 are provided in this order in a power transmission path from an engine 10 to drive wheels 13. The engine 10 and the motor 15 are mounted as a driving power source for the hybrid vehicle 1. The engine 10 is, for example, a V6 gasoline engine, but the number of cylinders is not limited thereto, and may be an in-line gasoline engine or a diesel engine. The K0 clutch 14, the motor 15, the torque converter 18, and the transmission 19 are provided in a transmission unit 11. The transmission unit 11 and the left and right drive wheels 13 are drivingly connected via a differential 12.

[0010] The K0 clutch 14 is provided between the engine 10 and the motor 15 on the power transmission path. The K0 clutch 14 is switched from a released state to an engaged state when hydraulic pressure is supplied, connecting the power transmission between the engine 10 and the motor 15. The K0 clutch 14 is switched to a released state when the hydraulic pressure supply is stopped, cutting off the power transmission between the engine 10 and the motor 15. The engaged state is a state in which both engagement elements of the K0 clutch 14 are connected and the engine 10 and the motor 15 have the same rotation speed. The released state is a state in which both engagement elements of the K0 clutch 14 are separated.

[0011] The motor 15 is connected to the battery 16 via an inverter 17. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supplied from the battery 16, and also functions as a generator that generates electric power to charge the battery 16 in response to power transmission from the engine 10 and the drive wheels 13. The electric power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

[0012] The inverter 17 is controlled by the ECU 100 described later, and converts the DC voltage from the battery 16 into an AC voltage, or converts the AC voltage from the motor 15 into a DC voltage. In the case of powering operation in which the motor 15 outputs torque, the inverter 17 converts the DC voltage of the battery 16 into an AC voltage and adjusts the power supplied to the motor 15. In the case of regenerative operation in which the motor 15 generates power, the inverter 17 converts the AC voltage from the motor 15 into a DC voltage and adjusts the power supplied to the battery 16.

[0013] The torque converter 18 is a fluid coupling having a torque amplifying function. The transmission 19 is a stepped automatic transmission that switches the gear ratio in multiple stages by switching the gear stage, but is not limited thereto and may be a continuously variable automatic transmission. The transmission 19 is provided between the motor 15 and the driving wheels 13 on the power transmission path. The motor 15 and the transmission 19 are connected via the torque converter 18. The torque converter 18 is provided with a lock-up clutch 20 that is supplied with hydraulic pressure and is engaged to directly connect the motor 15 and the transmission 19.

[0014] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the torque converter 18, the transmission 19, and the lock-up clutch 20 via the hydraulic control mechanism 22. The hydraulic control mechanism 22 is provided with hydraulic circuits for the K0 clutch 14, the torque converter 18, the transmission 19, and the lock-up clutch 20, and various hydraulic control valves for controlling the operating hydraulic pressures thereof. It should be noted that a wet clutch may be provided instead of the torque converter 18.

[0015] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 100 as a control device for the vehicle. The ECU 100 is an electronic control unit including a calculation processing circuit that performs various calculation processes related to vehicle driving control, and a memory that stores control programs and data. The ECU 100 is an example of a vehicle control device, and functionally realizes a control unit, a calculation unit, and an adjustment unit, which will be described in detail later.

[0016] The ECU 100 controls the operation of the engine 10 and the motor 15. Specifically, the ECU 100 controls the torque and rotation speed of the engine 10 by controlling the throttle opening, ignition timing, and fuel injection amount of the engine 10. The ECU 100 controls the rotation speed and torque of the motor 15 by controlling the inverter 17 to adjust the amount of power exchanged between the motor 15 and the battery 16. The ECU 100 also controls the operation of the K0 clutch 14, the lock-up clutch 20, and the transmission 19 through the control of the hydraulic control mechanism 22.

[0017] The ECU 100 receives signals from an ignition switch 71, a crank angle sensor 72, a motor revolution speed sensor 73, an accelerator opening sensor 74, an airflow meter 75, a pressure sensor 76, and a water temperature sensor 77. The crank angle sensor 72 detects the rotation speed of a crankshaft of the engine 10. The motor revolution speed sensor 73 detects the rotation speed of an output shaft of the motor 15. The accelerator opening sensor 74 detects the accelerator pedal opening, which is the amount of depression of the accelerator pedal by the driver. The airflow meter 75 detects the amount of intake air of the engine 10. The pressure sensor 76 detects the pressure in the intake passage 35 downstream of a throttle valve 40 (hereinafter referred to as intake manifold pressure) which will be described later. The water temperature sensor 77 detects the temperature of the cooling water of the engine 10.

[0018] The ECU 100 runs the hybrid vehicle in either a motor mode or a hybrid mode. In the motor mode, the ECU 100 releases the K0 clutch 14 and runs the vehicle using the power of the motor 15. In the hybrid mode, the ECU 100 switches the K0 clutch 14 to an engaged state and runs the vehicle using at least the power of the engine 10. The hybrid mode includes a mode in which the vehicle runs using only the power of the engine 10, and a mode in which the motor 15 is powered and the vehicle runs using both the engine 10 and the motor 15 as power sources.

[0019] The driving mode is switched based on the vehicle's required driving force calculated from the vehicle speed and accelerator opening, and the state of charge of the battery 16. For example, when the required driving force is relatively small and the SOC (State Of Charge) indicating the amount of charge in the battery 16 is relatively high, the motor mode in which the engine 10 is stopped is selected to improve fuel efficiency. When the required driving force is relatively large or the SOC of the battery 16 is relatively low, the hybrid mode in which the engine 10 is driven is selected.

[0020] The ECU 100 executes intermittent operation control to automatically stop the engine 10 when a predetermined stop condition is satisfied, and to restart the automatically stopped engine 10 when a predetermined restart condition is satisfied. For example, when the accelerator opening becomes zero in the hybrid mode, the ECU 100 automatically stops the engine 10, assuming that the automatic stop condition is satisfied. Also, when the accelerator opening becomes greater than zero, for example, the ECU 100 automatically restarts the engine 10, assuming that the restart condition is satisfied. In the case of automatic stop, the ECU 100 releases the K0 clutch 14 to stop combustion. In the case of automatic restart, the ECU 100 cranks the engine 10 by the motor 15 via the K0 clutch 14 to start combustion, and then engages the K0 clutch 14. Also, when the engine 10 is automatically stopped and the engine 10 is coasting, if the accelerator opening increases again and the restart condition is satisfied, combustion starts and the K0 clutch 14 is engaged.

[0021] [Engine outline] FIG. 2 is a schematic diagram of the engine 10. The engine 10 has cylinders 30, pistons 31, connecting rods 32, a crankshaft 33, an intake passage 35, an intake valve 36, an exhaust passage 37, and an exhaust valve 38. FIG. 2 shows only one of the multiple cylinders 30 of the engine 10. An air-fuel mixture is burned in the cylinder 30. A piston 31 is accommodated in each cylinder 30 so as to be capable of reciprocating, and is connected to a crankshaft 33, which is an output shaft of the engine 10, via a connecting rod 32. The connecting rod 32 converts the reciprocating motion of the piston 31 into the rotational motion of the crankshaft 33.

[0022] The intake passage 35 is connected to the intake port of each cylinder 30 via an intake valve 36. The exhaust passage 37 is connected to the exhaust port of each cylinder 30 via an exhaust valve 38. An air flow meter 75, a pressure sensor 76, and a throttle valve 40 that adjusts the amount of intake air are provided in the intake passage 35. A catalyst 43 for purifying exhaust gas is provided in the exhaust passage 37.

[0023] Each cylinder 30 is provided with an in-cylinder injection valve 41. The in-cylinder injection valve 41 injects fuel directly into the cylinder 30. Note that instead of or in addition to the in-cylinder injection valve 41, a port injection valve that injects fuel toward an intake port may be provided. Each cylinder 30 is provided with an ignition device 42 that ignites a mixture of intake air introduced through the intake passage 35 and fuel injected by the in-cylinder injection valve 41 by spark discharge.

[0024] [Engine stop position control] When the engine 10 is automatically stopped, a stop position control is executed to control the stop position of the engine 10 by temporarily increasing the throttle opening. By setting the stop position of the engine 10 to a desired stop position, the cranking torque of the engine 10 required of the motor 15 when restarting the engine 10 can be reduced. Therefore, for example, when restarting the engine 10 while traveling in the motor mode, the portion of the output torque of the motor 15 consumed for the cranking torque is suppressed. This makes it possible to secure the torque consumed for traveling of the hybrid vehicle 1 out of the output torque of the motor 15, and to secure an operating range in which the hybrid vehicle 1 can travel in the motor mode, thereby improving fuel efficiency.

[0025] FIG. 3 is a timing chart showing an example of the stop position control of the engine 10. FIG. 3 shows the transition of the engine speed [rpm], the throttle opening [deg], and the intake manifold pressure [kPa]. The combustion of the engine 10 is stopped, and the throttle opening is controlled to a first opening A1 (hereinafter referred to as opening A1) to reduce the engine speed (time t1). The opening A1 is a value close to 0 and may be 0. Next, at a predetermined timing, the throttle opening is switched from the opening A1 to a second opening A2 (hereinafter referred to as opening A2) (time t2), and the throttle opening is maintained at the opening A2 for a predetermined time. The opening A2 is a value closer to the maximum opening than 0. Next, the throttle opening is switched from the opening A2 to a third opening A3 (hereinafter referred to as opening A3) (time t3). The opening A3 is a value close to 0 and may be 0. Due to such a temporary increase in the throttle opening, intake air is introduced into the intake passage 35 downstream of the throttle valve 40, and the intake manifold pressure increases to the target intake manifold pressure (time t4). The target intake manifold pressure is a target value of the intake manifold pressure suitable for stopping the engine 10.

[0026] Next, the intake valve 36 of the cylinder 30 in the intake stroke closes, and some of the intake air introduced downstream of the throttle valve 40 fills the cylinder 30 (time t5). The intake valve 36 of the cylinder 30 in the intake stroke closes, and some of the intake air fills the cylinder 30 (time t6). After that, the piston 31 of the cylinder 30 filled with intake air first is in the expansion stroke, and the piston 31 of the cylinder 30 filled with intake air next is in the compression stroke, and the rotation of the engine 10 stops (time t7). After that, the intake manifold pressure returns to atmospheric pressure (time t8).

[0027] In this way, the engine 10 stops at a position where the compression reaction forces of the intake air filled in the two cylinders 30 are balanced. As a result, when the engine 10 is restarted, combustion can start from the cylinder 30 where the piston 31 stopped during the compression stroke, ensuring restartability. The stop position control is an example of a process executed by the control unit.

[0028] [Throttle opening increase timing adjustment control] As described above, in the stop position control, intake air is charged to a predetermined number of cylinders by switching the throttle opening from A1 to A2. If the timing at which the throttle opening is switched from A1 to A2 (hereinafter referred to as the increase timing) is not appropriate, the number of cylinders sufficiently filled with intake air may be insufficient or excessive, which may reduce the accuracy of the stop position. Therefore, the ECU 100 of this embodiment executes the following adjustment control of the increase timing of the throttle opening.

[0029] 4 is a flow chart showing an example of throttle opening increase timing adjustment control executed by the ECU 100. This control is repeatedly executed at predetermined intervals with the ignition on. The ECU 100 judges whether or not the engine 10 is executing the stop position control (step S1). If the answer is No in step S1, this control ends.

[0030] If the answer is Yes in step S1, the ECU 100 calculates the number of cylinders that are sufficiently filled with intake air (hereinafter referred to as the number of filled cylinders) (step S2). Specifically, if the intake manifold pressure at the timing when each cylinder 30 closes the intake valve 36 is equal to or higher than a predetermined value, the cylinder is counted as being sufficiently filled with intake air. Next, the ECU 100 determines whether or not the stop position control has ended, i.e., whether or not the rotation of the engine 10 has stopped (step S3). If the answer is No in step S3, step S2 continues. Step S2 is an example of a process executed by the calculation unit.

[0031] If the answer is Yes in step S3, the ECU 100 determines whether the calculated number of cylinders filled is less than the target number (step S4). If the answer is Yes in step S4, it can be determined that the timing of increasing the throttle opening is too late compared to the appropriate timing. Note that, in the case of an engine having six cylinders such as the engine 10 of this embodiment, the target number refers to two cylinders: one in which the piston stops during the expansion stroke (hereinafter referred to as an expansion stroke stopped cylinder) and one in which the piston stops during the compression stroke (hereinafter referred to as a compression stroke stopped cylinder), but is not limited to this.

[0032] If the answer is Yes in step S4, ECU 100 subtracts "1" from the HI counter value, adds "1" to the LO counter value, and resets the normal counter value (step S5). The HI counter value is a value that is added when the number of filled cylinders is greater than the target number, and is subtracted when the number of filled cylinders is less than the target number. The LO counter value is a value that is subtracted when the number of filled cylinders is greater than the target number, and is added when the number of filled cylinders is less than the target number. The normal counter value is a value that is added when the number of filled cylinders matches the target number, and is reset when the number of filled cylinders is greater than or less than the target number. ECU 100 constantly counts and updates these counter values ​​while the ignition is on.

[0033] If the answer is No in step S4, the ECU 100 determines whether the number of cylinders filled is greater than the target number (step S6). If the answer is Yes in step S6, the increase timing can be deemed to be too early with respect to the appropriate timing. If the answer is Yes in step S6, the ECU 100 adds "1" to the HI counter value, subtracts "1" from the LO counter value, and resets the normal counter (step S7).

[0034] If the answer is No in step S6, the number of cylinders charged can be regarded as the target number of cylinders, but the ECU 100 judges whether the amount of intake air charged in the compression stroke stopped cylinders is greater than the amount of intake air charged in the expansion stroke stopped cylinders (step S8). Specifically, if the intake manifold pressure when the intake valve 36 is closed before the compression stroke stopped cylinder is stopped is higher than the intake manifold pressure when the intake valve 36 is closed before the expansion stroke stopped cylinder is stopped, the answer is Yes in step S8. In this case, the number of cylinders charged is determined to be the target number, but it is considered that the intake valve 36 of the expansion stroke stopped cylinder is closed while the intake manifold pressure is rising, and then the intake valve 36 of the compression stroke stopped cylinder is closed after the intake manifold pressure has risen sufficiently. That is, in this case, it is considered that the increase timing is slightly later than the appropriate timing. Therefore, if the answer is Yes in step S8, step S5 is executed.

[0035] If the answer is No in step S8, the ECU 100 assumes that the target number of cylinders have been properly filled with intake air, and adds "1" to the normal counter value (step S9). Next, the ECU 100 determines whether the normal counter value is equal to or greater than a predetermined value (step S10). If the answer is Yes in step S10, the ECU 100 subtracts "1" from each of the HI counter value and the LO counter value, and resets the normal counter value (step S11).

[0036] After execution of step S5 or S11, the ECU 100 judges whether the HI counter value is equal to or greater than a predetermined value (step S12). If the answer is Yes in step S12, the ECU 100 delays the increase timing by a predetermined time (step S13).

[0037] If the answer is No in step S12, the ECU 100 determines whether the LO counter value is equal to or greater than a predetermined value (step S14). If the answer is Yes in step S14, the ECU 100 advances the increase timing by a predetermined time (step S15). If the answer is No in step S14, the number of cylinders charged is considered to match the target number at the current stage, the increase timing is considered to be appropriate, and this control ends. That is, if the answer is No in step S14, the increase timing is not adjusted and is maintained at the current timing. Similarly, if the answer is No in step S10, the number of cylinders charged is considered to match the target number at the current stage, and this control ends.

[0038] As described above, when the number of cylinders filled with fuel matches the target number, the increase timing is maintained, when the number of cylinders filled with fuel is greater than the target number, the increase timing is delayed, and when the number of cylinders filled with fuel is less than the target number, the increase timing is advanced. By adjusting the increase timing in this manner, the number of cylinders filled with fuel can be made to match the target number, and a decrease in the accuracy of the stopping position of the engine 10 is suppressed.

[0039] Any method may be used to adjust the increase timing. For example, the increase timing may be adjusted by adding or subtracting a predetermined minute crank angle to the increase timing associated with the crank angle. In addition, in a case where the required intake manifold pressure required to stop the engine 10 is constantly calculated and the increase timing is determined to be the point at which the required intake manifold pressure drops to a feasible pressure value, the increase timing may be adjusted by adding or subtracting a predetermined minute pressure to the required intake manifold pressure. In this way, the increase timing is adjusted by controlling a parameter directly or indirectly related to the increase timing.

[0040] In steps S5, S7, S9, and S11, the values ​​added to and subtracted from the counter values ​​are the same, but this is not limiting and some or all of them may be different. The respective predetermined values ​​in steps S12 and S14 may be the same or different.

[0041] In the above embodiment, a hybrid vehicle is controlled by a single ECU 100, but this is not limited to the above. The above-mentioned control may be performed by multiple ECUs, such as an engine ECU that controls the engine 10, a motor ECU that controls the motor 15, and a clutch ECU that controls the K0 clutch 14.

[0042] In the above embodiment, the hybrid vehicle 1 has been described as an example, but the invention is not limited to this. For example, the stop position control of the present embodiment can be applied to an engine vehicle that is provided with only an engine as a driving power source and in which the engine is automatically stopped and automatically restarted by an idling stop function.

[0043] 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 described in the claims. [Explanation of symbols]

[0044] 1 Hybrid vehicle (vehicle) 10 Engine (internal combustion engine) 15 Motor 40 Throttle valve 100 ECU (control unit, acquisition unit, adjustment unit)

Claims

[Claim 1] In a control device for a vehicle equipped with an internal combustion engine as a driving power source, a control unit that executes a stop position control of the internal combustion engine by temporarily increasing and then decreasing a throttle opening during inertial rotation in which combustion has stopped upon automatic stop of the internal combustion engine; a calculation unit that calculates the number of cylinders filled with intake air during the stop position control; and an adjustment unit that, when the number of cylinders filled matches a target number, maintains an increase timing, which is the timing at which the throttle opening starts to increase in the stop position control, and, when the number of cylinders filled is less than the target number, advances the increase timing compared to when the number of cylinders filled matches the target number, and, when the number of cylinders filled is greater than the target number, delays the increase timing compared to when the number of cylinders filled matches the target number.

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