Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device which secures start-up performance of an engine while the same is in inertial rotation.SOLUTION: In a hybrid vehicle in which a clutch and a motor are arranged in this order on a power transmission path from an engine to wheels, a control device comprises: a start-up control section which causes combustion in an engine to be started by cranking the engine with the motor through the clutch when a request is made for starting up the engine by cranking the same in inertial rotation with the clutch released and the combustion stopped; and a throttle control section which makes pressure in an intake passage at a downstream side of a throttle valve higher when the request is made for starting up the engine in the inertial rotation than the same when the request is not made for starting up the engine in the inertial rotation by increasing an opening of the throttle valve of the engine before starting the combustion in the engine.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] 2. Description of the Related Art Hybrid vehicles are known in which a clutch and a motor are provided in this order on a power transmission path between an engine and wheels (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-152337 A Summary of the Invention [Problem to be solved by the invention]

[0004] There are cases where the engine is required to be started while the engine is coasting after the clutch is released and engine combustion has stopped. During coasting, the throttle valve is closed, so the intake manifold pressure, which is the pressure in the intake passage downstream of the throttle valve, becomes negative. The intake manifold pressure at the point of transition from coasting to starting varies greatly depending on the engine's rotational behavior and the timing of starting. Therefore, fluctuations in intake manifold pressure during coasting may affect the startability of the engine.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS The present invention has an object to provide a control device for a hybrid vehicle that ensures engine startability during coasting. [Means for solving the problem]

[0006] The above object is to provide a vehicle in which a clutch and a motor are provided in order on a power transmission path between an engine and wheels. The throttle valve is provided with a pressure sensor for detecting an intake manifold pressure, which is a pressure in an intake passage downstream of the throttle valve of the engine.In the control device for a hybrid vehicle, when there is a request to start the engine by cranking the engine during coasting rotation with the clutch released and combustion stopped, a start control unit cranks the engine by the motor via the clutch to start combustion in the engine, and but In some cases When the intake manifold pressure is less than a predetermined value, When the engine is in freewheeling and there is no start request and when the engine is in coasting and there is a start request but the intake manifold pressure is equal to or higher than the predetermined value. before combustion begins in the engine. The above By increasing the throttle valve opening The intake manifold pressure and a throttle control unit for increasing the After the intake manifold pressure is increased to or above the predetermined value by the throttle control unit, combustion in the engine is started by the start control unit. This can be achieved by a control device for a hybrid vehicle. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control device for a hybrid vehicle that ensures the startability of the engine during inertial rotation. [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 flowchart showing an example of the negative pressure elimination 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 wheels 13. The engine 10 and the motor 15 are mounted as a driving source for running 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 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 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 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 in an engaged state 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 control device for a hybrid vehicle, and functionally realizes a start control unit and a throttle control 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, and a pressure sensor 76. The crank angle sensor 72 detects the rotation speed of the crankshaft of the engine 10. The motor revolution speed sensor 73 detects the rotation speed of the 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 37 downstream of a throttle valve 40, which will be described later (hereinafter referred to as intake manifold pressure).

[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 in the hybrid mode or the engine mode, and to start the automatically stopped engine 10 when a predetermined start condition is satisfied. For example, when the accelerator opening becomes zero in the hybrid mode or the engine mode, the ECU 100 automatically stops the engine 10 as the automatic stop condition is satisfied. Also, when the accelerator opening becomes larger than zero, the ECU 100 automatically starts the engine 10 as the start condition is satisfied. When automatically stopping the engine 10, the ECU 100 releases the K0 clutch 14 to stop fuel injection. When automatically starting the engine 10, the ECU 100 cranks the engine 10 by the motor 15 via the K0 clutch 14 to start fuel injection and ignition, and then engages the K0 clutch 14.

[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 start control] As described above, during execution of intermittent operation control, immediately after the accelerator opening becomes zero and the engine 10 is automatically stopped, the accelerator opening increases again, requesting the start of the engine 10. At the time of such a start request, the engine 10 may be rotating by inertia, although combustion has stopped. In this case, cranking is started by the motor 15 via the K0 clutch 14 while the engine 10 is rotating by inertia, and the engine 10 is started.

[0025] During inertial rotation after combustion is stopped, the throttle valve 40 is in a fully closed state in order to suppress vibration of the engine 10. Therefore, the intake manifold pressure, which is the pressure in the intake passage 35 downstream of the throttle valve 40, is a negative pressure lower than the outside air pressure. Even in the combustion-stop state, the piston 31 reciprocates in the cylinder 30 with the throttle valve 40 closed, opening and closing the intake valve 36 and the exhaust valve 38, and the air in the intake passage 35 is discharged to the exhaust passage 37. Since the number of times that air is discharged per hour increases as the engine speed increases, the intake manifold pressure, which is the negative pressure at the time of starting, may vary depending on the speed at which the throttle valve 40 is fully closed and the timing of starting, which may affect the startability.

[0026] 3 is a flowchart showing an example of negative pressure elimination control executed by the ECU 100. This control is repeatedly executed at a predetermined cycle while the ignition is on. The ECU 100 determines whether the engine 10 is rotating by inertia and whether there is a request to start the engine 10 by cranking the motor 15 (step S1). If the answer is No in step S1, this control ends. If the answer is Yes in step S1, the ECU 100 determines whether the intake manifold pressure is less than a predetermined value P (step S2). The predetermined value P is a negative pressure lower than the outside air pressure, and is set to a minimum pressure value that does not affect startability even if the engine 10 is started with the fixed value of the starting opening TS.

[0027] If the answer is No in step S2, it is deemed that the intake manifold pressure is unlikely to affect the startability of the engine 10 during inertial rotation, and the ECU 100 executes start control of the engine 10 (step S4). The start control transitions the K0 clutch 14 from a released state to an engaged state, cranks the engine 10 by the motor 15, and starts combustion in the engine 10, while controlling the throttle opening to a fixed value, TS, for starting. Step S4 is an example of control executed by the start control unit.

[0028] If the answer is Yes in step S2, it is deemed that the intake manifold pressure may affect the startability of the engine 10 during coasting, and the ECU 100 increases the throttle opening to the negative pressure resolving opening TN (step S3). The negative pressure resolving opening TN is a larger opening than the throttle opening controlled when there is no request to start the engine 10 during coasting. The negative pressure resolving opening TN does not necessarily have to be fully open, and is preferably an opening at which the intake manifold pressure becomes equal to or exceeds a predetermined value P in a relatively short time during coasting. This causes the intake manifold pressure to increase.

[0029] Next, the ECU 100 executes the process of step S2 again. That is, the throttle opening is maintained at the negative pressure resolving opening TN until the intake manifold pressure becomes equal to or greater than the predetermined value P. If the determination in step S2 is No after step S3, it is considered that the intake manifold pressure has risen to a level that is unlikely to affect the startability of the engine 10 during inertial rotation, and the ECU 100 executes start control (step S4). Steps S2 and S3 are an example of control executed by the throttle control unit.

[0030] As described above, the throttle opening is increased to the negative pressure resolving opening TN before cranking is started, and the intake manifold pressure is increased to the predetermined value P or more, and then the start control of the engine 10 is executed. This makes it possible to suppress the fluctuation of the intake manifold pressure even during coasting, and to suppress the variation in the intake air amount caused by the fluctuation of the intake manifold pressure. In addition, since the fluctuation of the intake manifold pressure is suppressed, it is possible to appropriately adjust, for example, the timing of the ignition timing according to the intake manifold pressure. In addition, by increasing the intake manifold pressure during coasting, it is possible to eliminate a shortage of the intake air amount caused by the intake manifold pressure being too low. As described above, the startability of the engine 10 during coasting can be ensured.

[0031] In the above embodiment, the intake manifold pressure is increased to or above the predetermined value P before the start of cranking, but even after cranking has started, the intake manifold pressure may be increased to or above the predetermined value P before the start of combustion in the engine 10. In this case, it is desirable to control the throttle opening to the starting opening TS at the start of combustion.

[0032] In the above embodiment, the case where the engine 10 is requested to be started by cranking has been described. However, when the engine 10 is started during coasting without cranking, the throttle opening is controlled to the starting opening TS without increasing it to the negative pressure resolving opening TN, and the engine 10 is started. The case where the engine 10 is started during coasting without cranking is when the engine speed during coasting is high enough to start the engine 10 without cranking. Specifically, it is when the engine speed is equal to or higher than the expected initial explosion speed. In this case, if the throttle opening is increased to the negative pressure resolving opening TN before starting the engine 10, the amount of intake air into the cylinder 30 increases rapidly, and the engine 10 may vibrate due to the repulsive force of the air in the cylinder 30 during the compression stroke.

[0033] In the above embodiment, the throttle opening is increased when the intake manifold pressure is less than a predetermined value P, but this is not limited to this. Regardless of the intake manifold pressure, when there is a request to start the engine 10 by cranking during inertial rotation, the throttle opening may be uniformly increased to the negative pressure resolving opening NV before cranking begins.

[0034] In the above embodiment, the start control is started by increasing the intake manifold pressure to a predetermined value P or more. However, the invention is not limited to this. For example, the start control may be executed by increasing the intake manifold pressure to a value higher than the intake manifold pressure when there is no request for starting by cranking during inertial rotation.

[0035] 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.

[0036] 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]

[0037] 10 Engine 14 K0 clutch 15 Motor 40 Throttle valve 100 ECU (start control unit, throttle control unit)

Claims

[Claim 1] A control device for a hybrid vehicle, in which a clutch and a motor are provided in this order on a power transmission path between an engine and wheels, and which is provided with a pressure sensor for detecting an intake manifold pressure which is a pressure in an intake passage downstream of a throttle valve of the engine, a start control unit that, when there is a request to start the engine by cranking while the engine is rotating by inertia with the clutch released and combustion stopped, cranks the engine by the motor via the clutch to start combustion in the engine; a throttle control unit that, when there is a start request for the engine during coasting and the intake manifold pressure is less than a predetermined value, increases the opening degree of the throttle valve before combustion starts in the engine to increase the intake manifold pressure, compared to a case in which there is no start request for the engine during coasting and a case in which there is a start request for the engine during coasting but the intake manifold pressure is equal to or greater than the predetermined value, A control device for a hybrid vehicle, wherein after the intake manifold pressure is increased to or above the predetermined value by the throttle control unit, combustion in the engine is started by the start control unit.

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