Control device for vehicle

Abstract

To start an engine properly.SOLUTION: A control device for a vehicle includes a lock-up control valve which controls a lock-up piston and a control system which is provided with a processor. A spool valve axis of the lock-up control valve makes it possible to move to a fastening position which supplies hydraulic oil to an applying oil passage and to a release position which supplies the hydraulic oil to a release oil passage and to an intermediate position between the fastening position and the release position. The control system holds the spool valve axis in the intermediate position and executes a first start control which cranks the engine and moves the spool valve axis to the release position if engine start is unsuccessful and executes a second start control which cranks the engine.SELECTED DRAWING: Figure 10

Description

[Technical Field]

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

[0002] A torque converter connected to an engine is provided with a lock-up clutch that directly connects the crankshaft and turbine shaft (see Patent Documents 1 to 3). The lock-up clutch is controlled to an engaged state by supplying hydraulic oil to an apply chamber in the torque converter and discharging hydraulic oil from a release chamber. On the other hand, the lock-up clutch is controlled to a released state by supplying hydraulic oil to a release chamber in the torque converter and discharging hydraulic oil from the apply chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 54409 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-217271 [Patent Document 3] Japanese Patent Application Publication No. 2018-167738 Summary of the Invention [Problem to be solved by the invention]

[0004] To reduce hydraulic oil consumption by the torque converter, the lockup clutch may be controlled to a neutral state between an engaged state and a disengaged state. When the lockup clutch is controlled to the neutral state in this way, the torque capacity of the lockup clutch is controlled to approximately "0." This makes it possible to crank the engine while controlling the lockup clutch to the neutral state. However, if the lockup clutch is not properly controlled to the neutral state, the cranking speed may not be increased sufficiently, making it difficult to start the engine. Thus, there is a need to start the engine even when the lockup clutch is not properly controlled. [Means for solving the problem]

[0005] According to the present disclosure, a vehicle control device includes an engine connected to wheels via a power transmission path and a clutch provided in the power transmission path. The vehicle control device also includes a torque converter provided in the power transmission path and disposed between the engine and the clutch. The vehicle control device includes a lock-up piston housed in a case of the torque converter and separating an apply chamber and a release chamber within the case. The vehicle control device also includes a lock-up control valve connected to the apply chamber via an apply oil passage and connected to the release chamber via a release oil passage. The vehicle control device also includes a control system including a processor and a memory communicatively connected to each other. A spool valve shaft of the lock-up control valve is movable between an engaged position where hydraulic oil is supplied to the apply oil passage and discharged from the release oil passage, a disengaged position where hydraulic oil is supplied to the release oil passage and discharged from the apply oil passage, and an intermediate position between the engaged position and the disengaged position. When the engine start condition is met with the spool valve shaft moved to the intermediate position and the clutch engaged, the control system executes a first start control that cranks the engine with the spool valve shaft held at the intermediate position and the clutch engaged.When the engine start condition is not met with the first start control, the control system executes a second start control that cranks the engine with the spool valve shaft moved to the released position and the clutch engaged. [Effects of the Invention]

[0006] According to the present disclosure, the engine can be started. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a vehicle equipped with a vehicle control device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a vehicle control device. [Figure 3]FIG. 3 is a diagram showing an example of the basic structure of an electronic control unit. [Figure 4A] FIG. 4A is a diagram showing the power unit when the EV mode is executed. [Figure 4B] FIG. 4B is a diagram showing the power unit when the HEV mode is being executed. [Figure 5] FIG. 5 is a diagram showing an example of an execution region of the EV mode and the HEV mode. [Figure 6] FIG. 6 is a diagram showing a portion of the torque converter and the valve unit. [Figure 7A] FIG. 7A is a diagram showing the operating state of the lockup control valve. [Figure 7B] FIG. 7B is a diagram showing the operating state of the lockup control valve. [Figure 7C] FIG. 7C is a diagram showing the operating state of the lockup control valve. [Figure 8] FIG. 8 is a diagram showing the engine start situation when switching from the EV mode to the HEV mode. [Figure 9] FIG. 9 is a flowchart showing an example of an execution procedure for engine start control. [Figure 10] FIG. 10 is a flowchart showing an example of an execution procedure for engine start control. [Figure 11] FIG. 11 is a flowchart showing an example of a procedure for executing the target value correction control. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, identical or substantially identical configurations and elements will be designated by the same reference numerals and repeated description will be omitted.

[0009] <Overview of vehicle control device> Fig. 1 is a diagram showing a vehicle 11 equipped with a vehicle control device 10 according to one embodiment of the present disclosure. As shown in Fig. 1, the vehicle 11 has a power unit 14 consisting of an engine 12 and a transmission 13. An output shaft 15 of the power unit 14 is connected to wheels 18 via a propeller shaft 16 and a differential mechanism 17. The vehicle 11 shown in the figure is a rear-wheel drive vehicle, but is not limited to this and may be an all-wheel drive vehicle or a front-wheel drive vehicle.

[0010] Fig. 2 is a diagram showing an example configuration of the vehicle control device 10. As shown in Fig. 2, the transmission 13 of the power unit 14 has a continuously variable transmission mechanism 23 consisting of a primary pulley 20, a secondary pulley 21, and a drive chain 22. The engine 12 is connected to a primary shaft 24 that supports the primary pulley 20 via an input clutch (clutch) 25 and a torque converter 26. Furthermore, the wheels 18 are connected to a secondary shaft 27 that supports the secondary pulley 21 via an output shaft 15, a propeller shaft 16, and a differential mechanism 17. The input clutch 25 is a hydraulic clutch that constitutes part of a forward / reverse switching mechanism consisting of a planetary gear train or the like, and is a clutch that is engaged when the vehicle 11 is traveling forward.

[0011] The crankshaft 19 of the engine 12 is connected to the wheels 18 via a power transmission path 30 that includes a torque converter 26, a continuously variable transmission 23, etc. The power transmission path 30 also includes the torque converter 26 and an input clutch 25, with the torque converter 26 being disposed between the engine 12 and the input clutch 25. In the exemplary configuration shown in Fig. 2 , the power transmission path 30 includes the crankshaft 19, the torque converter 26, the turbine shaft 84, the input clutch 25, the primary shaft 24, the continuously variable transmission 23, the secondary shaft 27, the output shaft 15, the propeller shaft 16, the differential mechanism 17, etc.

[0012] A rotor 32 of a motor generator (travel motor) 31 is connected to the primary shaft 24. That is, the motor generator 31 is connected to the wheels 18 via a power transmission path 30 consisting of the continuously variable transmission mechanism 23. A battery pack 35 is connected to a stator 33 of the motor generator 31 via an inverter 34. A motor control unit 36, which is an electronic control unit, is connected to the inverter 34 to control switching elements (not shown) in the inverter 34. The motor control unit 36 ​​has the function of controlling the motor torque and motor rotation speed by controlling the current supply state of the stator 33 via the inverter 34. The battery pack 35 has a battery module 37 consisting of multiple battery cells (not shown) and a battery control unit 38, which is an electronic control unit. The battery control unit 38 has the function of monitoring the charging and discharging of the battery module 37.

[0013] The power unit 14 is provided with a valve unit 40 including a plurality of electromagnetic valves, oil passages, etc. The power unit 14 is also provided with an oil pump 41 driven by the engine 12 and the primary shaft 24, and an oil pump 43 driven by an electric motor 42. The hydraulic oil discharged from the oil pumps 41, 43 is controlled in terms of supply destination, pressure, etc. by the valve unit 40, and is supplied to the input clutch 25, the continuously variable transmission mechanism 23, etc. A transmission control unit 44, which is an electronic control unit, is connected to the valve unit 40 and the electric motor 42 in order to control the operating states of the valve unit 40 and the electric motor 42.

[0014] The oil pump 41 is connected to a pump shell 46 of the torque converter 26 via a chain mechanism 45 that has a one-way clutch 45a. The oil pump 41 is also connected to the primary shaft 24 via a chain mechanism 47 that has a one-way clutch 47a. When the engine 12 is operating, driving force is transmitted from the pump shell 46 to the oil pump 41 via the chain mechanism 45. On the other hand, even when the engine 12 is stopped, as long as the primary shaft 24 is rotating, driving force is transmitted from the primary shaft 24 to the oil pump 41 via the chain mechanism 47. When the engine 12 is stopped and the rotation speed of the primary shaft 24 is reduced, the oil pump 43 is driven by the electric motor 42.

[0015] The engine 12 is provided with a throttle valve 50 that adjusts the amount of intake air, an injector 51 that injects fuel, and an ignition device 52 that ignites the air-fuel mixture in the cylinder. A starter generator 55 is connected to a crankshaft 19 of the engine 12 via a belt mechanism 54. The starter generator 55 is a so-called ISG (Integrated Starter Generator) that functions as both a generator and an electric motor. That is, the starter generator 55 not only functions as a generator that generates electricity when rotated by the crankshaft 19, but also as an electric motor that rotates the crankshaft 19. For example, when a starting condition (described later) is met to start the engine 12, the starter generator 55 cranks the engine 12. An engine control unit 56, which is an electronic control unit, is connected to the throttle valve 50, the injector 51, the ignition device 52, and the starter generator 55.

[0016] <Control System> As shown in FIG. 2, the vehicle control device 10 has a control system 60 made up of multiple electronic control units. The vehicle control device 10 has the motor control unit 36, battery control unit 38, transmission control unit 44, and engine control unit 56 described above as electronic control units that make up the control system 60, as well as a vehicle control unit 61 that outputs control signals to the control units 36, 38, 44, and 56. These control units 36, 38, 44, 56, and 61 are communicably connected to one another via an in-vehicle network 62. The vehicle control unit 61 sets an operation target for the power unit 14 based on input information from the various control units 36, 38, 44, and 56 and various sensors described below. The vehicle control unit 61 also generates control signals corresponding to the operation targets of the power unit 14 and outputs these control signals to the engine control unit 56, the transmission control unit 44, etc.

[0017] Connected to the vehicle control unit 61 are a vehicle speed sensor 63 that detects the vehicle speed, which is the traveling speed of the vehicle 11, an accelerator sensor 64 that detects the accelerator opening, which is the amount of accelerator pedal operation, and a brake sensor 65 that detects the amount of brake pedal operation. Also connected to the vehicle control unit 61 are an engine rotation sensor 66 that detects the engine rotation speed, which is the rotation speed of the crankshaft 19, and a turbine rotation sensor 67 that detects the turbine rotation speed, which is the rotation speed of the turbine shaft 84. Also connected to the vehicle control unit 61 are a power switch 68 for starting and stopping the control system 60, and a warning light 69 provided on an instrument panel (not shown) or the like.

[0018] Fig. 3 is a diagram showing an example of the basic structure of the electronic control units 36, 38, 44, 56, and 61. As shown in Fig. 3, the electronic control units 36, 38, 44, 56, and 61 have a microcontroller 72 incorporating a processor 70, a main memory 71, and the like. A predetermined program is stored in the main memory 71, and the program is executed by the processor 70. The processor 70 and the main memory 71 are connected to each other so that they can communicate with each other. Note that multiple processors 70 may be incorporated into the microcontroller 72, and multiple main memories 71 may be incorporated into the microcontroller 72.

[0019] The electronic control units 36, 38, 44, 56, and 61 each include an input circuit 73, a drive circuit 74, a communication circuit 75, an external memory 76, and a power supply circuit 77. The input circuit 73 converts signals input from various sensors into signals that can be input to the microcontroller 72. The drive circuit 74 generates drive signals for devices such as the valve unit 40 based on signals output from the microcontroller 72. The communication circuit 75 converts signals output from the microcontroller 72 into communication signals directed to other electronic control units. The communication circuit 75 also converts communication signals received from other electronic control units into signals that can be input to the microcontroller 72. The power supply circuit 77 supplies a stable power supply voltage to the microcontroller 72, the input circuit 73, the drive circuit 74, the communication circuit 75, the external memory 76, and the like. The external memory 76, which may be a nonvolatile memory or the like, stores programs and various data.

[0020] <Driving mode> Fig. 4A is a diagram showing power unit 14 when EV mode is being executed, and Fig. 4B is a diagram showing power unit 14 when HEV mode is being executed. An EV (Electric Vehicle) mode and an HEV (Hybrid Electric Vehicle) mode are set as driving modes for vehicle 11. EV mode is a driving mode in which input clutch 25 is disengaged to drive motor generator 31, and HEV mode is a driving mode in which input clutch 25 is engaged to drive engine 12 and motor generator 31.

[0021] 4A, when the EV mode is executed, input clutch 25 is controlled to a disengaged state, engine 12 is controlled to a stopped state, and motor generator 31 is controlled to a power running state. This allows motor torque to be transmitted to wheels 18, and vehicle 11 can be driven using motor generator 31. When vehicle 11 is to be decelerated, motor generator 31 is controlled to a regenerative state, i.e., a power generating state.

[0022] As shown in Fig. 4B, when the HEV mode is executed, input clutch 25 is controlled to an engaged state, engine 12 is controlled to an operating state, and motor generator 31 is controlled to a powering state. This allows engine torque and motor torque to be transmitted to wheels 18, and vehicle 11 can be driven using engine 12 and motor generator 31. Needless to say, motor generator 31 may also be controlled to an idling state or a regenerative state depending on the driving conditions.

[0023] FIG. 5 is a diagram showing an example of the execution range of the EV mode and the HEV mode. As shown in FIG. 5, a boundary line L1 is set between the EV range where the EV mode is executed and the HEV range where the HEV mode is executed, separating the EV range from the HEV range. The required driving force shown in FIG. 5 is the driving force requested by the control system 60 to the power unit 14. The control system 60 is capable of calculating the required driving force based on the accelerator opening. In other words, the control system 60 calculates the required driving force to be larger as the accelerator opening increases, and calculates the required driving force to be smaller as the accelerator opening decreases.

[0024] As shown by arrow A1 in FIG. 5 , when the required driving force or vehicle speed decreases during HEV mode, causing the driving state to fall below boundary line L1 from the HEV region, the control system 60 determines a transition from HEV mode to EV mode. The control system 60 then switches the driving mode from HEV mode to EV mode by disengaging the input clutch 25 and stopping the engine 12. On the other hand, as shown by arrow B1 in FIG. 5 , when the required driving force or vehicle speed increases during EV mode, causing the driving state to exceed boundary line L1 from the EV region, the control system 60 determines a transition from EV mode to HEV mode. The control system 60 then starts the engine 12 and engages the input clutch 25, thereby switching the driving mode from EV mode to HEV mode. In this way, an increase in the required driving force exceeding boundary line L1 or an increase in the vehicle speed exceeding boundary line L1 corresponds to a mode switch request from EV mode to HEV mode, i.e., a condition for starting the engine 12.

[0025] <Torque converter> Fig. 6 is a diagram showing a portion of the torque converter 26 and the valve unit 40. As shown in Fig. 6, the torque converter 26 has a pump shell 46 that is connected to the crankshaft 19 of the engine 12 via a drive plate 80. The torque converter 26 also has a pump impeller 81 fixed to the pump shell 46, and a turbine runner 82 that faces the pump impeller 81. A turbine shaft 84 is connected to the turbine runner 82 via a turbine hub 83. Hydraulic oil is supplied to the torque converter 26, and engine torque is transmitted from the pump impeller 81 to the turbine runner 82 via the hydraulic oil.

[0026] Torque converter 26 has a lock-up clutch 90 that directly connects crankshaft 19 and turbine shaft 84. Lock-up clutch 90 has a lock-up piston 91 housed in pump shell (case) 46. Lock-up piston 91 is connected to turbine hub 83 via a damper mechanism 92. As shown in the figure, lock-up piston 91 is housed in pump shell 46, which defines an apply chamber 93 and a release chamber 94. That is, with lock-up piston 91 as the boundary, the apply chamber 93 is defined on the turbine runner 82 side, and the release chamber 94 is defined on the front cover 95 side of the pump shell 46.

[0027] A valve unit 40 is connected to the torque converter 26 to supply hydraulic oil to the apply chamber 93 and the release chamber 94. The valve unit 40 has a pressure control valve 100, a flow control valve 101, a lock-up control valve 102, and a duty control valve 103. The oil pumps 41, 43 are connected to the pressure control valve 100 via a pump oil passage 104, and hydraulic oil discharged from the oil pumps 41, 43 is supplied to the pressure control valve 100 via the pump oil passage 104. The pressure control valve 100 and the lock-up control valve 102 are connected via a supply oil passage 105, and hydraulic oil output from the pressure control valve 100 is supplied to the lock-up control valve 102 via the supply oil passage 105. The lock-up control valve 102 and the flow control valve 101 are connected via a discharge oil passage 106, and hydraulic oil discharged from the pressure control valve 100 is supplied to the flow control valve 101 via the discharge oil passage 106.

[0028] The lockup control valve 102 is connected to the apply chamber 93 via an apply oil passage 107, and is also connected to the release chamber 94 via a release oil passage 108. In addition, in order to control the operating state of the lockup control valve 102, which is an oil passage switching valve, a duty control valve 103 is connected to a pilot chamber 109 of the lockup control valve 102. As will be described later, the control system 60 controls the operating state of the lockup control valve 102 by adjusting the pilot pressure supplied to the pilot chamber 109 by controlling the duty ratio of the duty control valve 103.

[0029] <Lock-up control valve> 7A, 7B, and 7C are diagrams showing operating states of the lockup control valve 102. As shown in Fig. 7A, the lockup control valve 102 has a valve housing 110 in which a plurality of ports are formed, and a spool valve shaft 111 housed in the valve housing 110. The valve housing 110 has a supply port 112 to which the supply oil passage 105 is connected, discharge ports 113 and 114 to which the discharge oil passage 106 is connected, and a pilot port 115 to which the duty control valve 103 is connected. The valve housing 110 also has an apply port 116 to which the apply oil passage 107 is connected, and a release port 117 to which the release oil passage 108 is connected.

[0030] A spool valve shaft 111 having a plurality of valve bodies 120, 121, and 122 is movably housed in the valve housing 110. A pilot chamber 109 is defined between one end of the spool valve shaft 111 and the valve housing 110, and a spring chamber 118 is defined between the other end of the spool valve shaft 111 and the valve housing 110. A return spring 119 is assembled in the spring chamber 118, and the return spring 119 urges the spool valve shaft 111 toward a fastened position, which will be described later.

[0031] <Lock-up control valve engagement operation state> As shown in FIG. 7A, when engaging lockup clutch 90, control system 60 controls lockup control valve 102 to an engaged operating state. That is, control system 60 reduces the duty ratio of duty control valve 103 to reduce the pilot pressure, thereby causing spool valve shaft 111 to move to the engaged position (in the direction of arrow α) by the spring force of return spring 119. By moving spool valve shaft 111 to the engaged position in this manner, supply oil passage 105 and apply oil passage 107 are connected, and discharge oil passage 106 and release oil passage 108 are connected. As a result, as shown by arrow FL1 in FIG. 6, hydraulic oil is supplied to apply chamber 93 and discharged from release chamber 94, so that lockup piston 91 comes into contact with front cover 95, and lockup clutch 90 is controlled to an engaged state.

[0032] <Lock-up control valve release operation state> On the other hand, as shown in FIG. 7B, when releasing the lock-up clutch 90, the control system 60 controls the lock-up control valve 102 to a release operating state. That is, the control system 60 increases the duty ratio of the duty control valve 103 to increase the pilot pressure, thereby moving the spool valve shaft 111 to the release position against the spring force of the return spring 119 (in the direction of arrow β). By moving the spool valve shaft 111 to the release position in this manner, the supply oil passage 105 and the release oil passage 108 are connected, and the discharge oil passage 106 and the apply oil passage 107 are connected. As a result, as shown by arrow FL2 in FIG. 6, hydraulic oil is supplied to the release chamber 94 and discharged from the apply chamber 93, so that the lock-up piston 91 moves away from the front cover 95, and the lock-up clutch 90 is controlled to a released state.

[0033] <Lock-up control valve oil passage blocking state> FIG. 7C shows the oil passage blocking state of the lockup control valve 102. As shown in FIG. 7C, by adjusting the pilot pressure by controlling the duty ratio of the duty control valve 103, the spool valve shaft 111 can be stopped at an intermediate position between the engaged and released positions. By moving the spool valve shaft 111 to the intermediate position and stopping it in this manner, the discharge port 113 is blocked by the valve element 120, the supply port 112 is blocked by the valve element 121, and the discharge port 114 is blocked by the valve element 122. In other words, by stopping the spool valve shaft 111 at the intermediate position, the apply oil passage 107 is blocked by the spool valve shaft 111, and the release oil passage 108 is blocked by the spool valve shaft 111. At this time, the lockup clutch 90 is controlled to a neutral state between the engaged state and the released state, and the torque capacity of the lockup clutch 90 is controlled to approximately "0 [Nm]."

[0034] In this way, by stopping the spool valve shaft 111 at the intermediate position, that is, by controlling the lock-up control valve 102 to the oil passage shut-off state, the supply of hydraulic oil to the apply chamber 93 and the release chamber 94 can be stopped. This reduces the amount of hydraulic oil consumed by the lock-up clutch 90, thereby reducing the load on the oil pumps 41, 43 that discharge hydraulic oil. The lock-up control valve 102 is set to the oil passage shut-off state when the engine 12 is stopped and the vehicle speed is below a predetermined threshold V2, that is, when the amount of hydraulic oil discharged by the oil pumps 41, 43 decreases. This allows the power unit 14 to be appropriately controlled without causing a shortage of hydraulic oil, even in a situation where the amount of hydraulic oil discharged by the oil pumps 41, 43 decreases. In other words, by controlling the lock-up control valve 102 to the oil passage shut-off state, the load on the oil pumps 41, 43 can be reduced, thereby achieving the miniaturization and cost reduction of the oil pumps 41, 43.

[0035] As described above, when the lock-up control valve 102 is controlled to the oil passage blocking state, the flow rate of hydraulic oil supplied to the torque converter 26 is less than when the lock-up control valve 102 is controlled to the engagement operating state. In other words, when the spool valve shaft 111 moves to the intermediate position, the flow rate of hydraulic oil supplied to the torque converter 26 is less than when the spool valve shaft 111 moves to the engagement position. Also, when the lock-up control valve 102 is controlled to the oil passage blocking state, the flow rate of hydraulic oil supplied to the torque converter 26 is less than when the lock-up control valve 102 is controlled to the release operating state. In other words, when the spool valve shaft 111 moves to the intermediate position, the flow rate of hydraulic oil supplied to the torque converter 26 is less than when the spool valve shaft 111 moves to the release position. Controlling the lock-up control valve 102 to the oil passage blocking state to reduce the amount of hydraulic oil consumed by the lock-up clutch 90 is also called oil balance improvement lock-up control.

[0036] <Lock-up learning control> In order to accurately stop the spool valve shaft 111 at the intermediate position, it is necessary to appropriately correct the target duty ratio of the duty control valve 103. For this reason, the control system 60 periodically learns the relationship between the release timing of the lock-up clutch 90 and the actual duty ratio applied to the duty control valve 103 (hereinafter referred to as the actual duty ratio). For example, by executing a learning mode in which the lock-up clutch 90 is released immediately before stopping while keeping the engine 12 in the operating state, it is possible to learn the relationship between the release timing of the lock-up clutch 90 and the actual duty ratio.

[0037] When the control system 60 learns the relationship between the release timing and the actual duty ratio, it corrects the target duty ratio when controlling the lock-up control valve 102 to the oil passage cutoff state based on the learning result of the release timing and the actual duty ratio. That is, when the actual duty ratio with respect to the release timing has decreased compared to the previous value, the target duty ratio when controlling the lock-up control valve 102 to the oil passage cutoff state is corrected to the decreasing side. On the other hand, when the actual duty ratio with respect to the release timing has increased compared to the previous value, the target duty ratio when controlling the lock-up control valve 102 to the oil passage cutoff state is corrected to the increasing side.

[0038] When the lock-up clutch 90 is in the engaged state, the differential rotation between the engine speed and the turbine speed is "0", and when the lock-up clutch 90 is in the released state, the differential rotation between the engine speed and the turbine speed expands beyond a predetermined threshold. For this reason, the control system 60 detects the release timing of the lock-up clutch 90 based on the differential rotation between the engine speed and the turbine speed.

[0039] <Input Clutch Control in EV Mode> 4A, in the EV mode, the input clutch 25 is controlled to a released state in order to disconnect the stopped engine 12 from the wheels 18. However, even in the EV mode in which the engine 12 is stopped, if the vehicle speed is below a predetermined threshold V1, the control system 60 controls the input clutch 25 to an engaged state in preparation for switching from the EV mode to the HEV mode.

[0040] For example, when the accelerator pedal is depressed heavily in EV mode where the vehicle speed is below threshold V1, the driving mode is switched from EV mode to HEV mode, and it is necessary to quickly start engine 12 and engage input clutch 25. Here, in order to suppress the engagement shock of input clutch 25, it is necessary to synchronize the turbine rotation speed on the clutch input side with the primary rotation speed on the clutch output side, and then switch input clutch 25 to the engaged state.

[0041] However, at low vehicle speeds in EV mode, it is expected that the primary rotation speed will be low enough to fall below the idling rotation speed of the engine 12. If the engine 12 is started under such conditions where the primary rotation speed is low, the engine rotation speed will rise and significantly exceed the primary rotation speed, which may result in an engagement shock of the input clutch 25. Therefore, when the vehicle is in EV mode in which the engine 12 is stopped and the vehicle speed is below threshold value V1, the control system 60 engages the input clutch 25 in advance in preparation for switching to the HEV mode. Note that when the input clutch 25 is engaged in EV mode, a differential rotation speed occurs between the engine rotation speed and the turbine rotation speed, but this differential rotation speed is absorbed by the torque converter 26, which is a slip element.

[0042] <Engine start control> Next, engine start control when switching from EV mode to HEV mode will be described. Figure 8 is a diagram showing the engine start situation when switching from EV mode to HEV mode. As described above, when the vehicle speed is below threshold V1 in EV mode in which the engine 12 is stopped, the control system 60 controls the input clutch 25 to the engaged state in preparation for switching to HEV mode. Also, as described above, when the vehicle speed is below threshold V2 with the engine 12 stopped, that is, when the discharge rate of the oil pumps 41, 43 decreases, the control system 60 controls the lock-up control valve 102 to the oil passage blocking state. At this time, the torque capacity of the lock-up clutch 90 is controlled to "0 [Nm]".

[0043] That is, as shown in Figure 8, depending on the driving conditions of the vehicle 11, the engine 12 may be cranked by the starter generator 55 while the input clutch 25 is controlled to the engaged state and the torque capacity of the lock-up clutch 90 is controlled to "0 [Nm]." At this time, if the spool valve shaft 111 of the lock-up control valve 102 is shifted from the intermediate position toward the engaged position and the torque capacity of the lock-up clutch 90 is increased beyond "0 [Nm]," the required cranking torque may increase, making engine starting difficult. Therefore, the control system 60 starts the engine 12 by executing the following engine start control.

[0044] 9 and 10 are flowcharts showing an example of the execution procedure of engine start control. In the flowcharts of FIGS. 9 and 10, the steps are connected to each other at the points marked with the symbol A. Note that each step of the engine start control shown in FIGS. 9 and 10 is executed by the processor 70 constituting the control system 60. Furthermore, the engine start control is executed by the control system 60 at predetermined intervals.

[0045] 9, the control system 60 proceeds to step S10, where it determines whether or not the EV mode is being executed. If the control system 60 determines in step S10 that the EV mode is being executed, it proceeds to step S11, where it determines whether or not the input clutch 25 is engaged. If the control system 60 determines in step S11 that the input clutch 25 is engaged, it proceeds to step S12, where it determines whether or not the lock-up control valve 102 is in an oil passage blocking state. If the control system 60 determines in step S12 that the lock-up control valve 102 is in an oil passage blocking state, it proceeds to step S13, where it determines whether or not there is a mode switch request from the EV mode to the HEV mode.

[0046] If the control system 60 determines in step S13 that there is a mode change request from the EV mode to the HEV mode, the process proceeds to step S14, where the starter generator 55 cranks the engine 12. In other words, the cranking situation in step S14 is a situation in which the input clutch 25 is controlled to be in an engaged state and the torque capacity of the lock-up clutch 90 is controlled to 0 [Nm], as shown in Fig. 8. This cranking in step S14 corresponds to a first start control in which the engine 12 is cranked with the spool valve shaft 111 held in an intermediate position and the input clutch 25 engaged.

[0047] As shown in FIG. 10 , the control system 60 proceeds to step S15, where it determines whether the engine 12 has been started by cranking. If the control system 60 determines in step S15 that the engine 12 has not been started, that is, if it determines that the engine start is unsuccessful, it proceeds to step S16, where it records fail information indicating a start failure of the engine 12. The control system 60 also proceeds to step S17, where it controls the lockup control valve 102 to a release operating state, thereby controlling the lockup clutch 90 to a released state. Then, the control system 60 proceeds to step S18, where it executes cranking of the engine 12 by the starter generator 55. This cranking in step S18 corresponds to second start control in which the engine 12 is cranked with the spool valve shaft 111 moved to the released position and the input clutch 25 engaged.

[0048] Next, the control system 60 proceeds to step S19, where it determines whether the engine 12 has been started by cranking. If it is determined in step S19 that the engine 12 has not been started, that is, if it is determined that the engine start condition is unsuccessful, it proceeds to step S20, where it determines whether the number of times the engine start condition has been unsuccessful has reached a predetermined upper limit Nx (e.g., three times). If it is determined in step S20 that the number of times the engine start condition has been unsuccessful has reached the upper limit Nx, it proceeds to step S21, where it turns on the warning light 69 and cancels the engine start. On the other hand, if it is determined in step S20 that the number of times the engine 12 has been unsuccessful has not reached the upper limit Nx, it proceeds to step S18 again, where it causes the starter generator 55 to crank the engine 12.

[0049] As described above, when the conditions for starting the engine 12 are met in the low vehicle speed range in EV mode, the control system 60 executes first start control, which holds the spool valve shaft 111 in the intermediate position and cranks the engine 12 with the input clutch 25 engaged (step S14). If engine start through the first start control is unsuccessful, the control system 60 executes second start control, which moves the spool valve shaft 111 to the disengaged position and cranks the engine 12 with the input clutch 25 engaged (step S18). This allows the lockup clutch 90 to be disengaged and the engine 12 to be started properly, even if the spool valve shaft 111 of the lockup control valve 102 is displaced from the intermediate position toward the engaged position and the cranking torque required to start the engine has increased.

[0050] <Target value correction control> As described above, one of the causes of engine start failure is an inappropriate setting of the target duty ratio of the lock-up control valve 102. Therefore, the control system 60 corrects the target duty ratio of the lock-up control valve 102 by executing the following target value correction control. FIG. 11 is a flowchart showing an example of the execution procedure of the target value correction control. Each step of the target value correction control shown in FIG. 11 is executed by the processor 70 that constitutes the control system 60. Furthermore, the target value correction control is executed by the control system 60 at predetermined intervals.

[0051] As shown in FIG. 11 , the control system 60 proceeds to step S30, where it determines whether or not fail information indicating a start failure of the engine 12 has been recorded. If the control system 60 determines in step S30 that fail information has been recorded, it proceeds to step S31, where it corrects the target duty ratio toward the lock-up clutch release side. That is, since the illustrated duty control valve 103 is configured to reduce the duty ratio to engage the lock-up clutch 90, in step S31, it corrects the target duty ratio by adding a predetermined value to the target duty ratio. Then, after correcting the target duty ratio in step S31, the control system 60 proceeds to step S32, where it resets the fail information and exits the routine. On the other hand, if it determines in step S30 that fail information has not been recorded, it proceeds to step S33, where it exits the routine while maintaining the target duty ratio.

[0052] As described above, since a deviation in the target duty ratio is a factor in engine start failure, the control system 60 corrects the target duty ratio based on the fail information. This makes it possible to appropriately set the target duty ratio when moving the spool valve shaft 111 to the intermediate position, and to appropriately control the lock-up control valve 102 to the oil passage blocking state. In other words, even in a situation where the amount of hydraulic oil discharged by the oil pumps 41, 43 decreases, the power unit 14 can be appropriately controlled without causing a shortage of hydraulic oil.

[0053] <Modification> The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present disclosure. In the above description, the motor generator 31 is provided in the power unit 14, but this is not limited thereto, and the motor generator 31 may be omitted from the power unit 14. In other words, even in a vehicle that has only the engine 12 as a power source, the technology of the present disclosure can be effectively applied as long as the engine 12 is started when the vehicle is stopped or traveling at low speeds. Furthermore, in the above description, the control system 60 is configured by multiple electronic control units 36, 38, 44, 56, and 61, but this is not limited thereto, and the control system 60 may be configured by a single electronic control unit.

[0054] 7C , both the apply oil passage 107 and the release oil passage 108 are blocked by stopping the spool valve shaft 111 of the lockup control valve 102 at an intermediate position, but the present invention is not limited to this. In other words, if it is possible to reduce the flow rate of hydraulic oil directed toward the torque converter 26, the apply oil passage 107 may be communicated while the release oil passage 108 is blocked, or the release oil passage 108 may be communicated while the apply oil passage 107 is blocked. Furthermore, if it is possible to reduce the flow rate of hydraulic oil directed toward the torque converter 26, both the apply oil passage 107 and the release oil passage 108 may be communicated without blocking both the apply oil passage 107 and the release oil passage 108.

[0055] In the above description, the spool valve shaft 111 of the lockup control valve 102 is moved toward the engaged position by lowering the duty ratio of the duty control valve 103, but this is not limiting. That is, the spool valve shaft 111 of the lockup control valve 102 may be moved toward the engaged position by increasing the duty ratio of the duty control valve 103. Also, in the above description, a pilot-type lockup control valve 102 controlled by the duty control valve 103 is used, but this is not limiting, and a direct-acting lockup control valve may also be used. Also, in the above description, the control system 60 duty-controls the lockup control valve 102, but this is not limiting, and the operating state of the lockup control valve 102 may be controlled by other control methods.

[0056] In the illustrated example, the continuously variable transmission mechanism 23 is provided in the power unit 14, but this is not limited thereto, and an automatic transmission mechanism including a planetary gear or the like may be provided in the power unit 14. Also, in the above description, the engine 12 is cranked using the starter generator 55, but this is not limited thereto, and the engine 12 may be cranked using a starter motor dedicated to starting the engine. Furthermore, the threshold value V1 that is compared with the vehicle speed when engaging the input clutch 25 and the threshold value V2 that is compared with the vehicle speed when controlling the lockup control valve 102 to the oil passage cut-off state may be the same value or may be different values. [Explanation of symbols]

[0057] 10...vehicle control device, 12...engine, 18...wheel, 25...input clutch (clutch), 26...torque converter, 30...power transmission path, 31...motor generator (travel motor), 46...pump shell (case), 60...control system, 70...processor, 71...main memory, 91...lockup piston, 93...apply chamber, 94...release chamber, 102...lockup control valve, 107...apply oil passage, 108...release oil passage, 111...spool valve shaft

Claims

1. an engine coupled to wheels via a power transmission path; a clutch provided in the power transmission path; a torque converter provided in the power transmission path and disposed between the engine and the clutch; a lock-up piston housed in a case of the torque converter and defining an apply chamber and a release chamber within the case; a lock-up control valve connected to the apply chamber via an apply oil passage and connected to the release chamber via a release oil passage; a control system including a processor and a memory communicatively coupled to each other; and The spool valve shaft of the lockup control valve is the hydraulic oil supply mechanism is movable between an engagement position where hydraulic oil is supplied to the apply oil passage and discharged from the release oil passage, a release position where hydraulic oil is supplied to the release oil passage and discharged from the apply oil passage, and an intermediate position between the engagement position and the release position, The control system includes: When the engine start condition is met with the spool valve shaft moved to the intermediate position and the clutch engaged, a first start control for cranking the engine while the spool valve shaft is held at the intermediate position and the clutch is engaged; If the engine start by the first start control is unsuccessful, a second start control is executed to crank the engine while the spool valve shaft is moved to the release position and the clutch is engaged. Vehicle control device.

2. 2. The vehicle control device according to claim 1, When the spool valve shaft is moved to the intermediate position, the flow rate of hydraulic oil supplied to the torque converter is smaller than when the spool valve shaft is moved to the fastened position, When the spool valve stem is moved to the intermediate position, the flow rate of hydraulic oil supplied to the torque converter is smaller than when the spool valve stem is moved to the release position. Vehicle control device.

3. 2. The vehicle control device according to claim 1, The intermediate position of the spool valve shaft is a position where both the apply oil passage and the release oil passage are blocked. Vehicle control device.

4. 2. The vehicle control device according to claim 1, The control system engages the clutch when the engine is stopped and the vehicle speed is below a threshold. Vehicle control device.

5. 2. The vehicle control device according to claim 1, a traction motor connected to the wheels; Vehicle control device.

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