JP7509670B2 - Vehicle control device - Google Patents

Description

The present invention relates to a control device for a vehicle equipped with an engine, an electric motor, and a clutch capable of disconnecting the engine from the electric motor.

A vehicle control device is well known that includes an engine, an electric motor connected to a power transmission path between the engine and the drive wheels so that the power can be transmitted, a clutch that is provided between the engine and the electric motor in the power transmission path and whose control state is switched by controlling a hydraulic clutch actuator, and a hydraulic control circuit that supplies regulated hydraulic pressure to the clutch actuator. For example, a vehicle control device described in Patent Document 1 is such a device. Patent Document 1 discloses that when the engine is started, a transmission torque of the clutch is generated and the torque required for cranking the engine is output from the electric motor, that a hydraulic pressure command value for supplying hydraulic pressure to the clutch is temporarily set to a high first fill pressure prior to cranking the engine, and that learning control is performed to correct the first fill pressure based on the amount of fluctuation in the rotation speed of the electric motor when the engine is started.

JP 2018-83509 A

When the engine is stopped, the motor may output a predetermined torque that causes creep. In this case, when the power transmission in the power transmission path is interrupted in a non-driving position such as P or N position, or when the vehicle is stopped with the brake on, the predetermined torque is not required, so torque cut control is performed to prevent the motor from outputting the predetermined torque, and the rotation speed of the motor may become zero. When the engine is started under a situation where torque cut control is being performed, the engine cannot be cranked by engaging the clutch. Therefore, under such a situation, it is possible to realize engine start by releasing the torque cut control and then starting hydraulic control to switch the clutch to an engaged state. However, since the torque cut control cannot be immediately restored to a stable predetermined torque, etc., when the torque cut control is released, there is a possibility that phenomena caused by variations in the clutch hydraulic pressure relative to the hydraulic pressure command value, such as fluctuations in the rotation speed of the motor, may not be detected correctly. This may result in a risk of not being able to properly perform learning control that corrects the relationship that represents the correlation between the clutch hydraulic pressure and the hydraulic pressure command value.

The present invention was made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can appropriately perform learning control to correct the relationship that represents the correlation between the clutch oil pressure and the oil pressure command value when engine start is initiated while torque cut control is being executed.

The gist of the first invention is a control device for a vehicle including: (a) an engine; an electric motor connected to a power transmission path between the engine and drive wheels so as to be capable of transmitting power; a clutch whose control state is switched by controlling a hydraulic clutch actuator provided between the engine and the electric motor in the power transmission path; and a hydraulic control circuit that supplies regulated hydraulic pressure to the clutch actuator, (b) a start control unit that controls the electric motor so as to increase the output torque of the electric motor by a required cranking torque, which is a torque required for cranking the engine, when the engine is started, and controls the engine so that the engine starts operating; and (c) a cranking hydraulic pressure command value that adjusts the hydraulic pressure to the clutch actuator so that the clutch transmits the required cranking torque is output to the hydraulic control circuit as a hydraulic pressure command value that causes the hydraulic pressure to be supplied during an engagement transition in which the control state of the clutch is switched from a released state to an engaged state, and prior to the output of the cranking hydraulic pressure command value, The clutch control unit outputs a hydraulic command value for rapid filling to the hydraulic control circuit to improve the response of the hydraulic pressure to the clutch actuator so that the clutch is quickly brought to a packing completion state in which the pack clearance of the clutch is reduced; (d) when the engine is stopped, in a situation in which a predetermined torque that causes a creep phenomenon is output from the electric motor, if the state of the vehicle is a predetermined state in which the predetermined torque is unnecessary, an electric motor control unit executes torque cut control to prevent the electric motor from outputting the predetermined torque, and releases the torque cut control when the engine is started during the execution of the torque cut control; and (e) a learning control unit performs learning control to correct the relationship that represents the correlation between the hydraulic pressure during the engagement transition of the clutch and the hydraulic command value; and (f) when the engine is started during the execution of the torque cut control, the clutch control unit waits to output the hydraulic command value for rapid filling until a predetermined time has elapsed in which the predetermined torque is stably output after the release of the torque cut control has begun.

According to the first invention, when the engine is started during execution of torque cut control that does not output a predetermined torque that causes creep from the electric motor, the output of the hydraulic command value for rapid filling is put on hold until a predetermined time has elapsed from when release of torque cut control is initiated until the predetermined torque is stably output. Therefore, under conditions in which the predetermined torque is stably output, learning control is performed to correct the relationship that represents the correlation between the hydraulic pressure during the clutch engagement transition and the hydraulic command value. Therefore, when engine start is initiated during execution of torque cut control, learning control that corrects the relationship that represents the correlation between the clutch hydraulic pressure and the hydraulic command value can be appropriately performed.

1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and a control system for various controls in the vehicle. FIG. 2 is a partial cross-sectional view showing an example of a K0 clutch. 11 is a table illustrating an example of each phase in the K0 control phase definition. FIG. 4 is a diagram showing an example of a time chart when engine start control is executed; 1 is a flowchart explaining the main control operations of an electronic control device, and is a flowchart explaining the control operations for appropriately performing K0 learning control when engine start-up is initiated while creep cut control is being executed.

The following describes in detail an embodiment of the present invention with reference to the drawings.

Figure 1 is a diagram illustrating the general configuration of a vehicle 10 to which the present invention is applied, as well as a diagram illustrating the main parts of the control functions and control system for various controls in the vehicle 10. In Figure 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG, which are driving power sources for traveling. The vehicle 10 also has driving wheels 14 and a power transmission device 16 provided in the power transmission path between the engine 12 and the driving wheels 14.

The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has an engine control device 50, which includes a throttle actuator, a fuel injection device, an ignition device, and the like, provided on the vehicle 10, controlled by an electronic control device 90 (described later), thereby controlling the engine torque Te, which is the output torque of the engine 12.

The electric motor MG is a rotating electric machine that functions as a motor to generate mechanical power from electric power and as a generator to generate electric power from mechanical power, and is a so-called motor generator. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The electric motor MG controls the MG torque Tm, which is the output torque of the electric motor MG, by controlling the inverter 52 by an electronic control device 90 described later. For example, when the rotation direction of the electric motor MG is the same as the rotation direction when the engine 12 is operating, the MG torque Tm is a power torque in the positive torque on the acceleration side, and a regenerative torque in the negative torque on the deceleration side. Specifically, the electric motor MG generates power for running using electric power supplied from the battery 54 via the inverter 52 instead of or in addition to the engine 12. The electric motor MG also generates power using the power of the engine 12 and the driven force input from the drive wheels 14 side. The electric power generated by the electric motor MG is stored in the battery 54 via the inverter 52. The battery 54 is an electric storage device that supplies electric power to the electric motor MG. The electric power is also synonymous with electrical energy unless otherwise specified. The motive power is also synonymous with torque and force unless otherwise specified.

The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, and the like, in a case 18, which is a non-rotating member attached to the vehicle body. The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in the power transmission path between the engine 12 and the drive wheels 14. The torque converter 22 is connected to the engine 12 via the K0 clutch 20. The automatic transmission 24 is connected to the torque converter 22 and is interposed in the power transmission path between the torque converter 22 and the drive wheels 14. The torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the engine 12 and the drive wheels 14. The power transmission device 16 also includes a propeller shaft 28 connected to a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, and the like. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, and an electric motor connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22.

The electric motor MG is connected to the electric motor connecting shaft 36 in the case 18 so as to be capable of transmitting power. The electric motor MG is connected to the power transmission path between the engine 12 and the drive wheels 14, in particular to the power transmission path between the K0 clutch 20 and the torque converter 22 so as to be capable of transmitting power. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20. In other words, the torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the electric motor MG and the drive wheels 14. The torque converter 22 and the automatic transmission 24 each transmit the driving force from the driving force sources of the engine 12 and the electric motor MG to the drive wheels 14.

The torque converter 22 includes a pump wheel 22a connected to the motor connecting shaft 36, and a turbine wheel 22b connected to the transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20, and is also directly connected to the electric motor MG. The pump wheel 22a is an input member of the torque converter 22, and the turbine wheel 22b is an output member of the torque converter 22. The motor connecting shaft 36 is also an input rotating member of the torque converter 22. The transmission input shaft 38 is also an output rotating member of the torque converter 22, which is integrally formed with the turbine shaft that is rotated by the turbine wheel 22b. The torque converter 22 is a fluid-type transmission device that transmits driving force from each of the driving force sources (engine 12, electric motor MG) to the transmission input shaft 38 via a fluid. The torque converter 22 includes an LU clutch 40 that connects the pump wheel 22a and the turbine wheel 22b. The LU clutch 40 is a direct clutch that connects the input and output rotating members of the torque converter 22, i.e., a well-known lock-up clutch.

The LU clutch 40 switches between operating and control states by changing the LU torque Tlu, which is the torque capacity of the LU clutch 40, using the LU oil pressure PRlu, which is a regulated oil pressure supplied from the oil pressure control circuit 56 provided in the vehicle 10. The control states of the LU clutch 40 include a fully released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slipping, and a fully engaged state in which the LU clutch 40 is engaged. When the LU clutch 40 is in the fully released state, the torque converter 22 is in a torque converter state in which a torque amplification effect is obtained. When the LU clutch 40 is in the fully engaged state, the torque converter 22 is in a lock-up state in which the pump impeller 22a and the turbine impeller 22b are rotated together.

The automatic transmission 24 is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear sets (not shown) and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices that are composed of, for example, multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. The engagement devices CB have their respective torque capacities, or CB torques Tcb, changed by the CB hydraulic pressure PRcb, which is a pressure-regulated hydraulic pressure supplied from the hydraulic control circuit 56, thereby switching the control state, such as the engaged state or the released state.

The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γat (=AT input rotation speed Ni/AT output rotation speed No) is formed by engaging one of the engagement devices CB. The automatic transmission 24 selectively forms a plurality of gear stages, in other words, the gear stages formed according to the driver's (=operator's) accelerator operation and the vehicle speed V, etc., by the electronic control device 90 described later. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is the input rotation speed of the automatic transmission 24. The AT input rotation speed Ni is also the rotation speed of the output rotating member of the torque converter 22, and is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. The AT input rotation speed Ni can be expressed as the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

The K0 clutch 20 is a wet or dry friction engagement device, for example, composed of a multi-plate or single-plate clutch pressed by a hydraulic clutch actuator 120, which will be described later. The K0 clutch 20 has its control state switched between an engaged state, a released state, etc., by the clutch actuator 120 being controlled by an electronic control device 90, which will be described later.

2 is a partial cross-sectional view showing an example of the K0 clutch 20. In FIG. 2, the K0 clutch 20 includes a clutch drum 100, a clutch hub 102, a separate plate 104, a friction plate 106, a piston 108, a return spring 110, a spring bearing plate 112, and a snap ring 114. The clutch drum 100 and the clutch hub 102 are provided on the same axis CS. FIG. 2 shows the radial outer periphery of the K0 clutch 20 in the upper half of the axis CS. The axis CS is the axis of the engine connecting shaft 34, the electric motor connecting shaft 36, etc. The clutch drum 100 is connected to, for example, the engine connecting shaft 34 and is rotated integrally with the engine connecting shaft 34. The clutch hub 102 is connected to, for example, the electric motor connecting shaft 36 and is rotated integrally with the electric motor connecting shaft 36. The separate plates 104 are fitted with a plurality of substantially annular plate-shaped outer peripheries on the inner periphery of the cylinder portion 100a of the clutch drum 100 so as not to rotate relative to the clutch hub 102, i.e., spline-fitted. The friction plates 106 are interposed between the plurality of separate plates 104, and are fitted with a plurality of substantially annular plate-shaped inner peripheries on the outer periphery of the clutch hub 102 so as not to rotate relative to the clutch hub 102, i.e., spline-fitted. The piston 108 is provided with a pressing portion 108a on its outer periphery, which extends toward the separate plates 104 and the friction plates 106. The return spring 110 is interposed between the piston 108 and a spring receiving plate 112, and biases a part of the piston 108 so as to abut against the bottom plate portion 100b of the clutch drum 100. In other words, the return spring 110 functions as a spring element that biases the piston 108 so as to bring the separate plates 104 and the friction plates 106 into a non-engagement state. The snap ring 114 is fixed to the cylindrical portion 100a of the clutch drum 100 at a position where the separate plate 104 and the friction plate 106 are sandwiched between the pressing portion 108a of the piston 108 and the snap ring 114. In the K0 clutch 20, an oil chamber 116 is formed between the piston 108 and the bottom plate portion 100b of the clutch drum 100. In the clutch drum 100, an oil passage 118 leading to the oil chamber 116 is formed. In the K0 clutch 20, the clutch drum 100, the piston 108, the return spring 110, the spring receiving plate 112, the oil chamber 116, etc. form a clutch actuator 120 as a hydraulic actuator.

The hydraulic control circuit 56 supplies the adjusted hydraulic pressure, K0 hydraulic pressure PRk0, to the clutch actuator 120. In the K0 clutch 20, when the K0 hydraulic pressure PRk0 is supplied from the hydraulic control circuit 56 to the oil chamber 116 through the oil passage 118, the piston 108 moves toward the separate plate 104 and the friction plate 106 against the biasing force of the return spring 110 due to the K0 hydraulic pressure PRk0, and the pressing portion 108a of the piston 108 presses the separate plate 104 and the friction plate 106. When the separate plate 104 and the friction plate 106 are pressed, the K0 clutch 20 is switched to an engaged state. The control state of the K0 clutch 20 is switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, due to the K0 hydraulic pressure PRk0. In addition, the torque capacity of the engagement devices such as the LU torque Tlu, the CB torque Tcb, and the K0 torque Tk0 corresponds to the maximum torque that the engagement device can transmit, i.e., the maximum transmission torque, and in the narrow sense, is different from the transmission torque of the engagement device, which corresponds to the torque that the engagement device actually transmits. However, in this embodiment, unless otherwise specified, the transmission torque of the engagement device also represents the maximum torque that the engagement device can transmit. For example, the K0 torque Tk0 is the same as the transmission torque of the K0 clutch 20.

The K0 torque Tk0 is determined by, for example, the friction coefficient of the friction material of the friction plate 106 and the K0 oil pressure PRk0. In the K0 clutch 20, when the oil chamber 116 is filled with hydraulic oil OIL and the pressure of the piston 108 (=PRk0 x piston pressure area) counteracts the biasing force of the return spring 110 to close the clearance between the separate plate 104 and the friction plate 106, that is, when the pack clearance of the K0 clutch 20 is closed, so-called packing is completed. In this embodiment, the state in which the pack clearance of the K0 clutch 20 is closed is referred to as the packing completion state. In the K0 clutch 20, the K0 torque Tk0 is generated by further increasing the K0 oil pressure PRk0 from the packing completion state. In other words, the packing completion state of the K0 clutch 20 is the state in which the K0 clutch 20 begins to have torque capacity, i.e., the K0 torque Tk0 begins to be generated, if the K0 oil pressure PRk0 is increased from the packing completion state. The K0 oil pressure PRk0 for packing the K0 clutch 20 is the K0 oil pressure PRk0 for bringing the piston 108 to the stroke end and bringing the state in which the K0 torque Tk0 is not being generated.

Returning to FIG. 1, when the K0 clutch 20 is engaged, the pump impeller 22a and the engine 12 are rotated together via the engine connecting shaft 34. That is, when the K0 clutch 20 is engaged, it connects the engine 12 and the drive wheels 14 so that power can be transmitted. On the other hand, when the K0 clutch 20 is released, the power transmission between the engine 12 and the pump impeller 22a is interrupted. That is, when the K0 clutch 20 is released, it disconnects the engine 12 and the drive wheels 14. Since the electric motor MG is connected to the pump impeller 22a, the K0 clutch 20 is provided in the power transmission path between the engine 12 and the electric motor MG and functions as a clutch that disconnects the power transmission path, that is, a clutch that disconnects the engine 12 from the electric motor MG. In other words, the K0 clutch 20 is a disconnecting clutch that connects the engine 12 and the electric motor MG when engaged, and disconnects the connection between the engine 12 and the electric motor MG when released.

In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the drive wheels 14 via the K0 clutch 20, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. In addition, the power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the drive wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc., regardless of the control state of the K0 clutch 20.

The vehicle 10 is equipped with a MOP 58, which is a mechanical oil pump, an EOP 60, which is an electric oil pump, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is rotated and driven by a driving force source (engine 12, electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is a motor dedicated to the EOP 60 for rotating and driving the EOP 60. The EOP 60 is rotated and driven by the pump motor 62 to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 58 and EOP 60 is supplied to the hydraulic control circuit 56. The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the LU hydraulic pressure PRlu, and the like, which are adjusted based on the hydraulic oil OIL discharged by the MOP 58 and/or the EOP 60.

The vehicle 10 further includes an electronic control device 90 that includes a control device for the vehicle 10 related to starting control of the engine 12, etc. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input/output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 90 includes computers for engine control, electric motor control, hydraulic control, etc. as necessary.

The electronic control device 90 receives various signals based on detection values from various sensors provided in the vehicle 10 (e.g., engine rotation speed sensor 70, turbine rotation speed sensor 72, output rotation speed sensor 74, MG rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, brake switch 82, battery sensor 84, oil temperature sensor 86, etc.) (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12, turbine rotation speed Nt, which is the same value as AT input rotation speed Ni, AT output rotation speed No corresponding to vehicle speed V, electric motor M The following signals are supplied: MG rotation speed Nm, which is the rotation speed of G; accelerator opening θacc, which is the amount of accelerator operation by the driver that indicates the magnitude of the driver's acceleration operation; throttle valve opening θth, which is the opening of the electronic throttle valve; brake-on signal Bon, which is a signal indicating that the brake pedal for operating the wheel brakes is being operated by the driver; battery temperature THbat, battery charge/discharge current Ibat, battery voltage Vbat of battery 54; hydraulic oil temperature THoil, which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56, etc.

The electronic control device 90 outputs various command signals (e.g., engine control command signal Se for controlling the engine 12, MG control command signal Sm for controlling the electric motor MG, CB hydraulic control command signal Scb for controlling the engagement device CB, K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, LU hydraulic control command signal Slu for controlling the LU clutch 40, EOP control command signal Seop for controlling the EOP 60, etc.) to each device (e.g., engine control device 50, inverter 52, hydraulic control circuit 56, pump motor 62, etc.) provided in the vehicle 10.

The electronic control device 90 includes a hybrid control means, i.e., a hybrid control unit 92, a clutch control means, i.e., a clutch control unit 94, and a gear shift control means, i.e., a gear shift control unit 96 to realize various controls in the vehicle 10.

The hybrid control unit 92 includes a function as an engine control means, i.e., an engine control unit 92a, that controls the operation of the engine 12, and a function as an electric motor control means, i.e., an electric motor control unit 92b, that controls the operation of the electric motor MG via the inverter 52, and executes hybrid drive control using the engine 12 and the electric motor MG, etc., by using these control functions.

The hybrid control unit 92 calculates the drive demand amount of the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand amount map. The drive demand amount map is a relationship that is experimentally or design-wise determined and stored in advance, i.e., a predetermined relationship. The drive demand amount is, for example, the required drive torque Trdem at the drive wheels 14. In other words, the required drive torque Trdem [Nm] is the required drive power Prdem [W] at the vehicle speed V at that time. The drive demand amount can also be the required drive force Frdem [N] at the drive wheels 14, the required AT output torque at the transmission output shaft 26, etc. In calculating the drive demand amount, the AT output rotation speed No, etc. may be used instead of the vehicle speed V.

The hybrid control unit 92 outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Sm for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable power Win and dischargeable power Wout of the battery 54, etc. The engine control command signal Se is, for example, a command value for the engine power Pe, which is the power of the engine 12 that outputs the engine torque Te at the current engine rotation speed Ne. The MG control command signal Sm is, for example, a command value for the power consumption Wm of the electric motor MG that outputs the MG torque Tm at the current MG rotation speed Nm.

The chargeable power Win of the battery 54 is the maximum power that can be input, which specifies the limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which specifies the limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control unit 90, for example, based on the battery temperature THbat and the state of charge value SOC [%] of the battery 54. The state of charge value SOC of the battery 54 is a value that indicates the state of charge of the battery 54, and is calculated by the electronic control unit 90, for example, based on the battery charge/discharge current Ibat and the battery voltage Vbat.

When the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 sets the driving mode to the motor driving (=EV driving) mode. In the EV driving mode, the hybrid control unit 92 performs EV driving, in which the vehicle runs using only the electric motor MG as a driving force source with the K0 clutch 20 in the released state. On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 92 sets the driving mode to the engine driving mode, i.e., hybrid driving (=HV driving) mode. In the HV driving mode, the hybrid control unit 92 performs engine driving, i.e., HV driving, in which the vehicle runs using at least the engine 12 as a driving force source with the K0 clutch 20 in the engaged state. On the other hand, even if the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 establishes the HV driving mode when the state of charge value SOC of the battery 54 is less than a predetermined engine start threshold value or when the engine 12, etc., needs to be warmed up. The engine start threshold is a predetermined threshold for determining that the state of charge value SOC is at a value at which it is necessary to forcibly start the engine 12 and charge the battery 54. In this way, the hybrid control unit 92 switches between the EV driving mode and the HV driving mode by automatically stopping the engine 12 during HV driving, restarting the engine 12 after the engine has stopped, or starting the engine 12 during EV driving, based on the required driving torque Trdem, etc.

The hybrid control unit 92 further includes a function as a start control means, i.e., a start control unit 92c, and a function as a stop control means, i.e., a stop control unit 92d.

The start control unit 92c determines whether or not there is a request to start the engine 12. For example, in the EV driving mode, the start control unit 92c determines whether or not there is a request to start the engine 12 based on whether or not the required drive torque Trdem has increased beyond the range that can be covered by the output of the electric motor MG alone, whether or not warming up of the engine 12, etc. is necessary, or whether or not the state of charge value SOC of the battery 54 is less than the engine start threshold. The start control unit 92c also determines whether or not the start control of the engine 12 has been completed.

The clutch control unit 94 controls the K0 clutch 20 to execute start control of the engine 12. For example, when the start control unit 92c determines that there is a request to start the engine 12, the clutch control unit 94 outputs a K0 hydraulic control command signal Sk0 to the hydraulic control circuit 56 to control the K0 clutch 20 in the released state toward the engaged state so that a K0 torque Tk0 is obtained for transmitting the torque required for cranking the engine 12, which is a torque that increases the engine rotation speed Ne, to the engine 12 side. In other words, when starting the engine 12, the clutch control unit 94 outputs a K0 hydraulic control command signal Sk0 to the hydraulic control circuit 56 to control the clutch actuator 120 to switch the control state of the K0 clutch 20 from the released state to the engaged state. In this embodiment, the torque required for cranking the engine 12 is called the required cranking torque Tcrn.

The start control unit 92c controls the engine 12 and the electric motor MG to execute start control of the engine 12. For example, when the start control unit 92c determines that there is a request to start the engine 12, it outputs an MG control command signal Sm to the inverter 52 so that the electric motor MG outputs the required cranking torque Tcrn in accordance with the switching of the K0 clutch 20 to the engaged state by the clutch control unit 94. In other words, when starting the engine 12, the start control unit 92c outputs an MG control command signal Sm to the inverter 52 so that the electric motor MG outputs the required cranking torque Tcrn, i.e., so that the MG torque Tm is increased by the required cranking torque Tcrn.

When the start control unit 92c determines that there is a request to start the engine 12, it outputs an engine control command signal Se to the engine control device 50 to start fuel supply, engine ignition, and the like, in conjunction with cranking of the engine 12 by the K0 clutch 20 and the electric motor MG. In other words, when starting the engine 12, the start control unit 92c outputs an engine control command signal Se to the engine control device 50 to control the engine 12 so that the engine 12 starts operating.

When cranking the engine 12, a cranking reaction torque Trfcr, which is a reaction torque associated with the engagement of the K0 clutch 20, is generated. During EV driving, this cranking reaction torque Trfcr causes a pulling sensation of the vehicle 10 due to the inertia during engine start, that is, a drop in the drive torque Tr. Therefore, the MG torque Tm that is increased toward the required cranking torque Tcrn when starting the engine 12 is the MG torque Tm for canceling the cranking reaction torque Trfcr, and is the MG torque Tm for compensating for the cranking reaction torque Trfcr, i.e., the MG torque Tm for K0 reaction compensation. The required cranking torque Tcrn is the K0 torque Tk0 required for cranking the engine 12, and is the MG torque Tm required for cranking the engine 12 that flows from the electric motor MG side to the engine 12 side via the K0 clutch 20. The required cranking torque Tcrn is, for example, a constant cranking torque Tcr that is determined in advance based on, for example, the specifications of the engine 12, the starting method of the engine 12, etc.

When starting the engine 12 during EV driving, the start control unit 92c causes the electric motor MG to output the MG torque Tm for the required cranking torque Tcrn in addition to the MG torque Tm for EV driving, i.e., the MG torque Tm that generates the driving torque Tr. Therefore, during EV driving, it is necessary to ensure the required cranking torque Tcrn in preparation for starting the engine 12. Therefore, the range in which the required driving torque Trdem can be satisfied only by the output of the electric motor MG is the torque range obtained by subtracting the required cranking torque Tcrn from the maximum torque that can be output by the electric motor MG. The maximum torque that can be output by the electric motor MG is the maximum MG torque Tm that can be output by the dischargeable power Wout of the battery 54.

The stop control unit 92d determines whether or not there is a request to stop the engine 12. For example, in the HV driving mode, the stop control unit 92d determines whether or not there is a request to stop the engine 12 based on whether or not the required drive torque Trdem is within a range that can be covered only by the output of the electric motor MG, there is no need to warm up the engine 12, and the state of charge value SOC of the battery 54 is equal to or higher than the engine start threshold.

The stop control unit 92d controls the engine 12 to execute stop control of the engine 12. For example, when the stop control unit 92d determines that there is a request to stop the engine 12, it outputs an engine control command signal Se to the engine control device 50 to stop the supply of fuel to the engine 12. In other words, when the engine 12 is stopped, the stop control unit 92d outputs an engine control command signal Se to the engine control device 50 to control the engine 12 so that the engine 12 stops operating.

The clutch control unit 94 controls the K0 clutch 20 when the engine 12 is stopped. For example, when the stop control unit 92d determines that there is a request to stop the engine 12, the clutch control unit 94 outputs a K0 hydraulic control command signal Sk0 to the hydraulic control circuit 56 to control the engaged K0 clutch 20 toward a released state. In other words, when it is determined that there is a request to stop the engine 12, that is, when there is a request to stop the engine 12, the clutch control unit 94 outputs a K0 hydraulic control command signal Sk0 to the hydraulic control circuit 56 to control the clutch actuator 120 to switch the control state of the K0 clutch 20 from an engaged state to a released state.

When the vehicle 10 is stopped in an EV driving mode with the accelerator off, the motor control unit 92b executes, for example, MG idling control CTmid, which is idling control of the motor MG. The MG idling control CTmid is a control for idling the motor MG by maintaining the MG rotation speed Nm at the MG idle rotation speed Nmidl, which is a predetermined idling rotation speed of the motor MG. The MG idling control CTmid is also a control for outputting a creep torque Tcp by the motor MG from a stopped state of the vehicle 10 when, for example, the engine 12 is stopped and the accelerator is off. The creep torque Tcp is a predetermined torque for causing a creep phenomenon in which the vehicle 10 moves slowly with the accelerator off, for example, due to the brake being off during a temporary stop, and is a torque for running the vehicle 10 in a so-called creep running state when the brake is off and the accelerator is off in a vehicle stopped state. In this way, when the engine 12 is stopped and the vehicle 10 is stopped with the accelerator off, the motor control unit 92b causes the motor MG to output creep torque Tcp.

When the engine 12 is stopped and the vehicle 10 is in a predetermined state in which the creep torque Tcp is unnecessary under conditions in which the creep torque Tcp is output from the motor MG, the motor control unit 92b executes creep cut control CTccp as torque cut control that does not output the creep torque Tcp from the motor MG. The predetermined state is, for example, a predetermined state of the vehicle 10, such as a non-driving position such as P or N position in which the automatic transmission 24 is in a neutral state, or a vehicle stopped with the brakes on.

The shift control unit 96 uses, for example, a shift map, which is a predetermined relationship, to determine whether to shift the automatic transmission 24, and outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 to execute shift control of the automatic transmission 24 as necessary. The shift map is a predetermined relationship having a shift line for determining whether to shift the automatic transmission 24 on a two-dimensional coordinate system with, for example, vehicle speed V and required driving torque Trdem as variables. In the shift map, the AT output rotation speed No may be used instead of the vehicle speed V, and the required driving force Frdem, accelerator opening θacc, throttle valve opening θth, etc. may be used instead of the required driving torque Trdem.

Here, in order to accurately control the control state of the K0 clutch 20 when starting the engine 12, a K0 control phase definition Dphk0 is predefined in the electronic control unit 90. The K0 control phase definition Dphk0 defines multiple progression stages, or phases, for controlling the clutch actuator 120, which are divided according to the control state of the K0 clutch 20 that is switched during the engine 12 startup process.

Figure 3 is a chart explaining an example of each phase in the K0 control phase definition Dphk0. In Figure 3, the K0 control phase definition Dphk0 defines phases such as "K0 standby", "quick apply", "constant pressure standby when packing", "K0 cranking", "quick drain", "constant pressure standby before re-engagement", "initial rotation synchronization", "middle rotation synchronization", "final rotation synchronization", "engagement transition sweep", "full engagement transition sweep", "full engagement", "backup sweep", and "calculation stop".

The "K0 standby" phase is a phase in which control of the K0 clutch 20 is not started and the engine 12 is kept on standby during startup control of the engine 12. The "K0 standby" phase is entered if a K0 standby determination is made when starting control of the engine 12.

The "quick apply" phase is a phase in which a quick apply is performed to apply a temporarily high command value for the K0 oil pressure PRk0 in order to quickly complete packing of the K0 clutch 20, thereby improving the initial responsiveness of the K0 oil pressure PRk0. The "quick apply" phase is entered if there is no K0 standby determination when starting control of the engine 12. Alternatively, the "quick apply" phase is entered from the "K0 standby" phase if the K0 standby determination is withdrawn while waiting for control of the K0 clutch 20 to begin.

The command value of the K0 hydraulic pressure PRk0 is a hydraulic pressure command value for causing the hydraulic control circuit 56 to supply the adjusted K0 hydraulic pressure PRk0. In this embodiment, the command value of the K0 hydraulic pressure PRk0 is referred to as the K0 hydraulic pressure command value Spk0. The K0 hydraulic pressure command value Spk0 is uniquely converted into an instruction current for a solenoid driver that drives the solenoid valve for the K0 clutch 20 provided in the electronic control device 90. The solenoid valve for the K0 clutch 20 is a solenoid valve that outputs the K0 hydraulic pressure PRk0 provided in the hydraulic control circuit 56. The K0 hydraulic pressure control command signal Sk0 is an instruction current for a solenoid driver that drives the solenoid valve for the K0 clutch 20, or a drive current or drive voltage supplied by this solenoid driver. In other words, the K0 hydraulic pressure command value Spk0 is converted into the K0 hydraulic pressure control command signal Sk0 and output to the hydraulic control circuit 56. In this embodiment, for convenience, the K0 hydraulic command value Spk0 and the K0 hydraulic control command signal Sk0 are treated as the same.

The "constant pressure standby during packing" phase is a phase in which the system waits at a constant pressure to complete packing of the K0 clutch 20. The "constant pressure standby during packing" phase is entered from the "quick apply" phase when the quick apply is completed.

The "K0 cranking" phase is a phase in which the engine 12 is cranked by the K0 clutch 20. The "K0 cranking" phase is entered from the "constant pressure standby during packing" phase when packing of the K0 clutch 20 is completed.

The "quick drain" phase is a phase in which a quick drain is executed to temporarily output a low K0 oil pressure command value Spk0 so that the next phase, the "constant pressure wait before re-engagement" phase, can quickly wait at a predetermined K0 oil pressure PRk0, for example, pack end pressure, thereby improving the initial responsiveness of the K0 oil pressure PRk0. The "quick drain" phase is entered from the "K0 cranking" phase when cranking of the engine 12 is completed and a quick drain execution determination is made.

The "constant pressure standby before re-engagement" phase is a phase in which the engine waits at a predetermined K0 torque Tk0 so as not to disturb the complete combustion of the engine 12. Complete combustion of the engine 12 is a state in which the engine 12 is in a stable state of independent rotation due to the explosion of the engine 12 after the initial explosion when ignition of the engine 12 is started, for example. Not disturbing the complete combustion of the engine 12 means not interfering with the independent rotation of the engine 12. The "constant pressure standby before re-engagement" phase is transitioned from the "K0 cranking" phase when cranking of the engine 12 is completed and there is no determination to perform a quick drain. Alternatively, the "constant pressure standby before re-engagement" phase is transitioned from the "quick drain" phase when a quick drain is completed.

The "initial rotation synchronization" phase is a phase in which the K0 torque Tk0 is controlled to assist in increasing the engine speed Ne in order to quickly synchronize the engine speed Ne with the MG speed Nm. The "initial rotation synchronization" phase is transitioned from the "constant pressure standby before re-engagement" phase if the transition conditions to the "final rotation synchronization" phase and the "middle rotation synchronization" phase are not satisfied when the engine control unit 92a notifies the engine 12 of complete combustion. The engine control unit 92a outputs a complete combustion notification of the engine 12 when, for example, the elapsed time from the time when the engine speed Ne reaches a predetermined complete combustion rotation speed of the engine 12 exceeds a predetermined complete combustion notification waiting time TMeng (see FIG. 4 described later). The complete combustion notification waiting time TMeng is predetermined, for example, taking into account the exhaust gas requirements of the engine 12.

The "rotational synchronization middle" phase is a phase in which the K0 torque Tk0 is controlled so that the engine 12 has an appropriate amount of revving (=Ne-Nm). The "rotational synchronization middle" phase is transitioned from the "constant pressure wait before re-engagement" phase if the transition condition to the "rotational synchronization middle" phase is satisfied when the engine control unit 92a notifies the engine control unit 92a of complete explosion. Alternatively, the "rotational synchronization middle" phase is transitioned from the "rotational synchronization initial" phase if the transition condition to the "rotational synchronization middle" phase is satisfied during the execution of the "rotational synchronization initial" phase.

The "rotational synchronization end" phase controls the K0 torque Tk0 to synchronize the engine rotation speed Ne and the MG rotation speed Nm. The "rotational synchronization end" phase is transitioned from the "constant pressure wait before re-engagement" phase if the transition condition to the "rotational synchronization end" phase is satisfied when the engine control unit 92a notifies the engine control unit 92a of complete explosion. Alternatively, the "rotational synchronization end" phase is transitioned from the "rotational synchronization initial" phase if the transition condition to the "rotational synchronization end" phase is satisfied during the execution of the "rotational synchronization initial" phase. Alternatively, the "rotational synchronization end" phase is transitioned from the "rotational synchronization middle" phase if the transition condition to the "rotational synchronization end" phase is satisfied during the execution of the "rotational synchronization middle" phase. Alternatively, the "rotation synchronization end" phase is transitioned from the "rotation synchronization middle" phase when the automatic transmission 24 is not being controlled during the execution of the "rotation synchronization middle" phase, and a state in which it is predicted that synchronization between the engine rotation speed Ne and the MG rotation speed Nm is impossible is continuously established for a period of time equal to or longer than the forced rotation synchronization transition determination time.

The "engagement transition sweep" phase is a phase in which the K0 torque Tk0 is gradually increased to bring the K0 clutch 20 into an engaged state. The "engagement transition sweep" phase is transitioned from the "rotational synchronization end" phase if a rotational synchronization determination is made during execution of the "rotational synchronization end" phase.

The "full engagement transition sweep" phase is a phase in which the K0 torque Tk0 is gradually increased to bring the K0 clutch 20 into a fully engaged state. Bringing the K0 clutch 20 into a fully engaged state means, for example, increasing the K0 torque Tk0 to a state in which a safety factor is added to ensure engagement of the K0 clutch 20. The "full engagement transition sweep" phase is transitioned from the "engagement transition sweep" phase when the K0 engagement determination is satisfied during execution of the "engagement transition sweep" phase. Alternatively, the "full engagement transition sweep" phase is transitioned from the "engagement transition sweep" phase when the rotational synchronization state of the K0 clutch 20 cannot be maintained during execution of the "engagement transition sweep" phase. Alternatively, the "full engagement transition sweep" phase is transitioned from the "engagement transition sweep" phase when the elapsed time from the start of the "engagement transition sweep" phase exceeds a predetermined forced engagement transition determination time and it is determined that the absolute value of the K0 differential rotation ΔNk0 is equal to or greater than the predetermined full engagement transition sweep forced transition determination differential rotation. The K0 differential rotation speed ΔNk0 is the differential rotation speed of the K0 clutch 20 (= Nm - Ne).

The "fully engaged" phase is a phase in which the K0 clutch 20 is maintained in a fully engaged state. The "fully engaged" phase is transitioned from the "fully engaged" phase if a full engagement determination is made during execution of the "fully engaged" phase. Alternatively, the "fully engaged" phase is transitioned from the "fully engaged" phase if it is determined that the elapsed time from the start of the "fully engaged" phase is equal to or greater than a predetermined forced full engagement transition determination time and that the absolute value of the K0 differential rotation ΔNk0 is equal to or greater than a predetermined forced full engagement transition determination differential rotation.

The "fully engaged" phase can also be transitioned from the "backup sweep" phase. The "fully engaged" phase is transitioned from the "backup sweep" phase when a fully engaged determination is made during execution of the "backup sweep" phase, and a determination that the absolute value of the K0 differential rotation ΔNk0 is equal to or less than the predetermined backup-time rotation synchronization determination differential rotation is made consecutively for a predetermined number of times or more. Alternatively, the "fully engaged" phase is transitioned from the "backup sweep" phase when, during execution of the "backup sweep" phase, the elapsed time from the transition to a phase other than the "K0 standby" phase after the start of engine 12 start control is equal to or more than the predetermined engine start control timeout time, and it is determined that the absolute value of the K0 differential rotation ΔNk0 is equal to or more than the fully engaged forced transition determination differential rotation.

The "backup sweep" phase is a phase in which backup control is performed by gradually increasing the K0 torque Tk0 to engage the K0 clutch 20. The "backup sweep" phase is transitioned from the currently running phase when it is determined that the elapsed time from the start of the currently running phase exceeds a predetermined backup transition determination time for the currently running phase and that the K0 differential rotation ΔNk0 is equal to or greater than the predetermined backup transition determination differential rotation for the currently running phase, for example, during the execution of any of the "K0 cranking" phase, the "constant pressure waiting before re-engagement" phase, the "initial rotation synchronization" phase, the "middle rotation synchronization" phase, and the "final rotation synchronization" phase, in order to prevent control stacking.

The "calculation stop" phase is a phase in which calculation of the base correction pressure of the K0 oil pressure PRk0 used for the start control of the engine 12 and the required K0 torque Tk0d is stopped while the fail-safe control is being executed at the start of the engine 12. The fail-safe control is a control to switch the oil path in the hydraulic control circuit 56 so that the K0 oil pressure PRk0 capable of maintaining the fully engaged state of the K0 clutch 20 is supplied to the clutch actuator 120 without passing through the solenoid valve for the K0 clutch 20 when a failure occurs in which the regulated K0 oil pressure PRk0 is not output from the solenoid valve for the K0 clutch 20. The K0 oil pressure PRk0 capable of maintaining the fully engaged state is, for example, an original pressure such as a line pressure supplied to the solenoid valve for the K0 clutch 20. The base correction pressure is a value obtained by correcting the base pressure of the K0 oil pressure PRk0 used for the start control of the engine 12 based on the hydraulic oil temperature THoil, etc. The required K0 torque Tk0d is the K0 torque Tk0 required to crank the engine 12 and switch the K0 clutch 20 to the engaged state during start control of the engine 12.

The K0 control phase definition Dphk0 is created for the purpose of calculating, for example, the base correction pressure of the K0 oil pressure PRk0 and the required K0 torque Tk0d used in the start-up control of the engine 12. In the K0 control phase definition Dphk0, each phase is defined based on the control request state for the K0 clutch 20, such as the desire to control the K0 oil pressure PRk0 and the K0 torque Tk0. In other words, the K0 control phase definition Dphk0 is defined based on the control request to switch the control state of the K0 clutch 20.

When starting the engine 12, the clutch control unit 94 controls the clutch actuator 120 to switch the control state of the K0 clutch 20 from a released state to an engaged state based on the K0 control phase definition Dphk0.

When starting the engine 12, the start control unit 92c controls the electric motor MG and the engine 12 in accordance with the control state of the K0 clutch 20. In starting control of the engine 12, it is sufficient to control the electric motor MG so that it outputs the required cranking torque Tcrn, and also to control the engine 12 so that the engine 12 starts operating. Therefore, when starting the engine 12, the start control unit 92c controls the electric motor MG and the engine 12 based on the phases of the K0 control phase definition Dphk0 that are required for controlling the electric motor MG and the engine 12. This simplifies the control when starting the engine 12.

Figure 4 is a diagram showing an example of a time chart when the start control of the engine 12 is executed. In Figure 4, "K0 control phase" shows the transition state of each phase in the K0 control phase definition Dphk0. In addition, the total oil pressure value obtained by adding the oil pressure value obtained by converting the required K0 torque Tk0d into the K0 oil pressure PRk0 to the base correction pressure of the K0 oil pressure PRk0 is output as the K0 oil pressure command value Spk0. Time t1 indicates the time when a start request for the engine 12 is made during EV driving mode in which the vehicle is stopped in an idling state or during EV driving, and the start control of the engine 12 is started. After the start control of the engine 12 is started, the "K0 standby" phase (see time t1-t2), the "quick apply" phase (see time t2-t3), and the "constant pressure standby during packing" phase (see time t3-t4) are executed. Following the packing control of the K0 clutch 20, the "K0 cranking" phase is executed (see time t4-t5). In the embodiment of FIG. 4, in the "constant pressure standby during packing" phase, the K0 oil pressure PRk0 corresponding to the required cranking torque Tcrn required in the "K0 cranking" phase is applied. In the "constant pressure standby during packing" phase, the actual K0 oil pressure PRk0 is not increased to a value that generates the K0 torque Tk0 or more. In the "K0 cranking" phase, the actual K0 oil pressure PRk0 is increased to a value that generates the K0 torque Tk0 or more. In the "constant pressure standby during packing" phase, the K0 oil pressure PRk0 for maintaining the K0 clutch 20 in the packing completion state may be applied. In the "K0 cranking" phase, the MG torque Tm having a magnitude that corresponds to the required K0 torque Tk0d, i.e., the required cranking torque Tcrn, is output from the electric motor MG. In the "K0 cranking" phase, when the engine rotation speed Ne is increased, engine ignition and the like are started and the engine 12 is first fired. In addition, when the ignition start is performed, for example, the engine 12 is initially fired at approximately the same time as the engine speed Ne starts to increase. After the initial firing of the engine 12, in order to prevent the engine 12 from being disturbed by the complete firing, the "K0 cranking" phase is followed by the "quick drain" phase (see time t5-t6) and the "constant pressure standby before re-engagement" phase (see time t6-t7), and a low K0 hydraulic pressure command value Spk0 is temporarily output. When the engine complete firing notification is output from the engine control unit 92a (see time t7), the "initial rotation synchronization" phase (see time t7-t8), the "middle rotation synchronization" phase (see time t8-t9), the "final rotation synchronization" phase (see time t9-t10), and the "engagement transition sweep ("engagement transition SW" in the figure)" phase (see time t10-t11) are executed, and the rotation synchronization control between the engine 12 and the electric motor MG is performed. Following the "engagement transition sweep" phase, a "full engagement transition sweep ("full engagement transition SW" in the figure)" phase is executed (see time t11-t12), and the K0 torque Tk0 is gradually increased to a state in which a safety factor is added to ensure engagement of the K0 clutch 20. When the K0 torque Tk0 is increased to a state in which a safety factor is added to ensure engagement of the K0 clutch 20, the "full engagement" phase is executed (see time t12-t13), and the full engagement state of the K0 clutch 20 is maintained. Time t13 indicates the time when start control of the engine 12 is completed.

Referring to the "K0 cranking" phase in FIG. 3 and FIG. 4, during the engagement transition in which the control state of the K0 clutch 20 is switched from the released state to the engaged state when the engine 12 is started, the clutch control unit 94 outputs to the hydraulic control circuit 56 the K0 hydraulic pressure command value Spk0 for cranking to adjust the K0 hydraulic pressure PRk0 to the clutch actuator 120 so that the K0 clutch 20 transmits the required cranking torque Tcrn as the K0 hydraulic pressure command value Spk0. In this embodiment, the K0 hydraulic pressure command value Spk0 for cranking is referred to as the cranking hydraulic pressure command value Spk0cr.

3 and 4, when starting the engine 12, the clutch control unit 94 outputs the K0 hydraulic pressure command value Spk0 for quick apply to the hydraulic control circuit 56 as the K0 hydraulic pressure command value Spk0 to improve the responsiveness of the K0 hydraulic pressure PRk0 to the clutch actuator 120 so that the K0 clutch 20 is quickly brought to a packing completion state, prior to outputting the cranking hydraulic pressure command value Spk0cr in the "K0 cranking" phase. The quick apply in the "quick apply" phase is also a first fill (= rapid fill) that quickly fills the oil chamber 116 of the clutch actuator 120 with hydraulic oil OIL, so the K0 hydraulic pressure command value Spk0 for quick apply is also the K0 hydraulic pressure command value Spk0 for rapid fill. In this embodiment, the K0 hydraulic pressure command value Spk0 for rapid fill is called the hydraulic pressure command value Spk0ff for rapid fill.

On the other hand, if the creep cut control CTccp is being executed while the vehicle is stopped, the creep torque Tcp is not output and the MG rotation speed Nm is set to zero or approximately zero. As a result, when starting the engine under circumstances in which the creep cut control CTccp is being executed, the engine 12 cannot be cranked by switching the K0 clutch 20 from a released state to an engaged state. For this reason, in circumstances in which the engine 12 is to be started while the creep cut control CTccp is being executed, the engine is started by releasing the creep cut control CTccp and then starting the output of the rapid fill hydraulic pressure command value Spk0ff.

If the engine 12 is started while the creep cut control CTccp is being executed, the motor control unit 92b cancels the creep cut control CTccp.

On the other hand, the K0 oil pressure PRk0 and K0 torque Tk0 vary with respect to the K0 oil pressure command value Spk0 due to various factors. This can cause the MG rotation speed Nm, etc. to deviate from the target rotation speed during the engagement transition of the K0 clutch 20 in the start control of the engine 12. For this reason, it is desirable to perform learning control that corrects the relationship that represents the correlation between the K0 oil pressure PRk0 and the K0 oil pressure command value Spk0.

The electronic control unit 90 is further equipped with a learning control means, i.e., a learning control unit 98, to realize control operations for appropriately controlling the engagement of the K0 clutch 20 when the engine 12 is started.

The learning control unit 98 performs learning control to correct the relationship representing the correlation between the K0 oil pressure PRk0 and the K0 oil pressure command value Spk0 during the engagement transition of the K0 clutch 20 related to the start of the engine 12. The relationship representing the correlation between the K0 oil pressure PRk0 and the K0 oil pressure command value Spk0 is, for example, the correlation between the actual K0 oil pressure PRk0r, which is the actual value of the K0 oil pressure PRk0, and the K0 oil pressure command value Spk0, the correlation between the actual K0 oil pressure PRk0r and the required K0 torque Tk0d, the correlation between the actual K0 torque Tk0r, which is the actual value of the K0 torque Tk0, and the K0 oil pressure command value Spk0, and the correlation between the actual K0 torque Tk0r and the required K0 torque Tk0d. The learning control that corrects the relationship that represents the correlation between the K0 hydraulic pressure PRk0 and the K0 hydraulic pressure command value Spk0 is, for example, a learning control that corrects the variation of the actual K0 hydraulic pressure PRk0r relative to the K0 hydraulic pressure command value Spk0. In other words, the learning control that corrects the relationship that represents the correlation between the K0 hydraulic pressure PRk0 and the K0 hydraulic pressure command value Spk0 is a learning control that corrects the variation of the K0 hydraulic pressure command value Spk0 to make the actual K0 torque Tk0r the required K0 torque Tk0d. In this embodiment, this learning control is called the K0 learning control CTlrnk0. In this embodiment, unless otherwise specified, the K0 hydraulic pressure PRk0 and the K0 torque Tk0 represent the actual values of each. Also, the variation of the K0 hydraulic pressure PRk0 and the variation of the K0 torque Tk0 are synonymous.

The K0 learning control CTlrnk0 is, for example, a learning control that corrects the quick apply time, which is the execution period of the quick apply in the "quick apply" phase before the generation of the K0 torque Tk0, a learning control that corrects the error in the rise timing when the K0 torque Tk0 is generated, and a learning control that corrects the variation of the K0 torque Tk0 relative to the K0 hydraulic command value Spk0 from the "K0 cranking" phase onwards after the generation of the K0 torque Tk0.

The learning control unit 98 acquires each learning parameter PAlrn as necessary for performing each of the multiple types of learning control in the K0 learning control CTlrnk0, and performs the K0 learning control CTlrnk0 based on the acquired learning parameter PAlrn. For example, in the K0 learning control CTlrnk0, the learning control unit 98 corrects the relationship representing the correlation between the K0 oil pressure PRk0 and the K0 oil pressure command value Spk0 during the engagement transition of the K0 clutch 20 so as to set the value of the learning parameter PAlrn to zero. The learning parameter PAlrn is a numerical value that represents a phenomenon that occurs due to, for example, the variation in the K0 oil pressure PRk0 relative to the K0 oil pressure command value Spk0.

The variation in the K0 torque Tk0, such as the occurrence of the K0 torque Tk0 in the "quick apply" phase before the occurrence of the K0 torque Tk0, or the magnitude or occurrence timing of the K0 torque Tk0 deviating from the target, appears as a fluctuation in the MG rotation speed Nm, such as an increase or decrease in the speed. For example, if the K0 torque Tk0 is smaller than the target value or the occurrence timing of the K0 torque Tk0 is slower than the target, the MG rotation speed Nm is increased by the MG torque Tm, which is relatively larger than the target, and the variation in the K0 torque Tk0 appears as the amount of speed increase in the MG rotation speed Nm. The amount of speed increase in the MG rotation speed Nm is a positive value of the MG rotation fluctuation amount ΔNm (=Nm-Nmtgt), which is the amount of fluctuation in the MG rotation speed Nm. The above "Nmtgt" is the target rotation speed of the MG rotation speed Nm, i.e., the target MG rotation speed. On the other hand, if the K0 torque Tk0 is greater than the target value or the timing of occurrence of the K0 torque Tk0 is earlier than the target, the MG rotation speed Nm is reduced by the MG torque Tm that is relatively smaller than the target, and the variation in the K0 torque Tk0 appears as a drop in the MG rotation speed Nm. The drop in the MG rotation speed Nm is a negative value of the MG rotation fluctuation amount ΔNm. Thus, an example of the learning parameter PAlrn is the MG rotation fluctuation amount ΔNm.

Alternatively, for example, MG feedback control CTfbm may be performed, which is a control that compensates for the surplus or deficiency of MG torque Tm by feedback control so that the MG rotation speed Nm is maintained at the target MG rotation speed Nmtgt. When MG feedback control CTfbm is performed, the variation in K0 torque Tk0 appears as, for example, MG torque fluctuation amount ΔTm (= Tmfb - Tmb), which is the amount of fluctuation in the compensated MG torque Tmfb after the surplus or deficiency has been compensated for by the MG feedback control CTfbm. The above "Tmb" is the basic MG torque when the MG rotation speed Nm does not deviate from the target MG rotation speed Nmtgt. In this way, the MG torque fluctuation amount ΔTm is also an example of a learning parameter PAlrn.

When the engine 12 is started while the creep cut control CTccp is being executed, the creep cut control CTccp is released, but the stable creep torque Tcp, MG idle speed Nmidl, etc. cannot be restored immediately after the creep cut control CTccp is released. Or, in the EV driving mode, since the MOP 58 is driven only by the power of the electric motor MG, when the EOP 60 is not operating normally, the original pressure of the K0 oil pressure PRk0 is supplied to the hydraulic control circuit 56 from the MOP 58 driven by the power of the electric motor MG. In this case, the flow rate of the hydraulic oil OIL required for the engagement control of the K0 clutch 20 at the start of the engine 12 is not sufficiently secured immediately after the creep cut control CTccp is released, and a stable K0 oil pressure PRk0 may not be obtained. If this happens, the learning parameters PAlrn, such as the MG rotation fluctuation amount ΔNm, may not be detected correctly, and the K0 learning control CTlrnk0 may not be performed properly.

Therefore, if the creep cut control CTccp is being executed when the engine 12 starts to start, in addition to releasing the creep cut control CTccp in time with the start of the engine 12 starting, after the release of the creep cut control CTccp starts, the start of control of the K0 clutch 20, i.e., the start of output of the K0 hydraulic command value Spk0 in the engagement control of the K0 clutch 20, is delayed until the creep torque Tcp, MG idle rotation speed Nmidl, K0 hydraulic pressure PRk0, etc., become stable. After the start of control of the K0 clutch 20 is delayed, the learning parameter PAlrn is acquired as necessary during the engagement transition of the K0 clutch 20.

When the engine 12 is started while the creep cut control CTccp is being executed, the clutch control unit 94 waits to output the rapid fill hydraulic command value Spk0ff until a predetermined time TMf has elapsed from when the release of the creep cut control CTccp is initiated until the creep torque Tcp is stably output. In other words, when the start control of the engine 12 is initiated, the clutch control unit 94 determines that there is a K0 standby judgment during the period from when the release of the creep cut control CTccp is initiated until the predetermined time TMf has elapsed. Therefore, the phase is transitioned to the "K0 standby" phase at least during the period from when the release of the creep cut control CTccp is initiated until the predetermined time TMf has elapsed.

Specifically, when the start control unit 92c determines that there is a request to start the engine 12, the clutch control unit 94 determines whether or not the creep cut control CTccp is being executed by the motor control unit 92b. When the clutch control unit 94 determines that the creep cut control CTccp is being executed, it outputs a creep cut release command to the motor control unit 92b to release the creep cut control CTccp. The motor control unit 92b starts releasing the creep cut control CTccp based on the creep cut release command from the clutch control unit 94.

The clutch control unit 94 determines whether a predetermined time TMf has elapsed since the motor control unit 92b started to release the creep cut control CTccp.

When the clutch control unit 94 determines that the creep cut control CTccp is not being executed, or when it determines that a predetermined time TMf has elapsed since the release of the creep cut control CTccp was initiated, it outputs a hydraulic command value Spk0ff for rapid filling to initiate quick apply, thereby initiating switching of the K0 clutch 20 to the engaged state.

The learning control unit 98 determines whether or not to perform the K0 learning control CTlrnk0 during the current engine start control. For example, when the K0 learning control CTlrnk0 is incomplete and the vehicle 10 is stable, the learning control unit 98 determines to perform the K0 learning control CTlrnk0. The learning control unit 98 determines whether or not the vehicle 10 is stable based on, for example, the vehicle speed V, the accelerator opening θacc, the gear stage of the automatic transmission 24, the MG rotation speed Nm, etc. The learning control unit 98 determines not to perform the K0 learning control CTlrnk0 when, for example, the K0 learning control CTlrnk0 is completed, the vehicle 10 is not stable, or the solenoid valve for the K0 clutch 20 or the like is determined to be malfunctioning.

When the learning control unit 98 determines to perform the K0 learning control CTlrnk0, it acquires the learning parameters PAlrn as necessary during the engagement transition of the K0 clutch 20 during the transition of the start control of the engine 12. The learning control unit 98 executes the K0 learning control CTlrnk0 using the acquired learning parameters PAlrn.

Figure 5 is a flowchart that explains the main control operations of the electronic control unit 90, and is a flowchart that explains the control operations for appropriately performing K0 learning control CTlrnk0 when engine start is initiated while creep cut control CTccp is being executed, and is executed, for example, repeatedly.

In FIG. 5, first, in step S10 (hereinafter, step will be omitted) corresponding to the function of the start control unit 92c, it is determined whether there is a request to start the engine 12. In other words, it is determined whether the start control of the engine 12 is started. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, it is determined in S20 corresponding to the function of the clutch control unit 94 whether the creep cut control CTccp is being executed. If the determination in S20 is positive, the release of the creep cut control CTccp is started in S30 corresponding to the function of the motor control unit 92b. Next, in S40 corresponding to the function of the clutch control unit 94, it is determined whether a predetermined time TMf has elapsed since the release of the creep cut control CTccp was started. If the determination in S40 is negative, this S40 is repeatedly executed. If the determination in S20 is negative, or if the determination in S40 is positive, then in S50, which corresponds to the function of the clutch control unit 94, a quick apply in the engagement control of the K0 clutch 20 is started, and switching of the K0 clutch 20 to the engaged state is started. Next, in S60, which corresponds to the function of the learning control unit 98, it is determined whether or not to perform the K0 learning control CTlrnk0 during the current engine start control. If the determination in S60 is negative, this routine is terminated. If the determination in S60 is positive, then in S70, which corresponds to the function of the learning control unit 98, the learning parameter PAlrn is acquired as necessary. Next, in S80, which corresponds to the function of the learning control unit 98, the K0 learning control CTlrnk0 is executed using the acquired learning parameter PAlrn.

As described above, according to this embodiment, when the engine 12 is started while the creep cut control CTccp is being executed, the output of the rapid fill hydraulic command value Spk0ff is put on hold until a predetermined time TMf has elapsed since the release of the creep cut control CTccp is initiated, so that the K0 learning control CTlrnk0 is performed under conditions in which the creep torque Tcp is stably output. Therefore, when the engine start is initiated while the creep cut control CTccp is being executed, the K0 learning control CTlrnk0 can be performed appropriately.

The above describes in detail an embodiment of the present invention based on the drawings, but the present invention can also be applied in other aspects.

For example, in the above embodiment, the learning parameter PAlrn may be any numerical value that represents a phenomenon caused by the variation of the K0 oil pressure PRk0 relative to the K0 oil pressure command value Spk0, and is not limited to the MG rotation fluctuation amount ΔNm or the MG torque fluctuation amount ΔTm.

In the above embodiment, the engine 12 is started in a manner in which the engine 12 is ignited in accordance with the cranking of the engine 12 in a transitional state in which the K0 clutch 20 is switched from a released state to an engaged state, and the engine 12 itself increases the engine rotation speed Ne, but this is not limited to the above embodiment. For example, the engine 12 may be started by cranking the engine 12 until the K0 clutch 20 is fully engaged or close to being fully engaged, and then igniting the engine 12. When the vehicle 10 is stopped and the MG rotation speed Nm is zero, a starting method can be adopted in which the engine 12 is cranked by the electric motor MG in the fully engaged state of the K0 clutch 20, and then ignited. In addition, if the vehicle 10 is equipped with a starter, which is a motor dedicated to cranking the engine 12, when the vehicle 10 is stopped and the MG rotation speed Nm is set to zero, for example, when the outside air temperature is extremely low and cranking by the electric motor MG is insufficient or impossible, a starting method can be adopted in which the engine 12 is cranked by the starter and then ignited.

In the above embodiment, a planetary gear type automatic transmission is exemplified as the automatic transmission 24, but the present invention is not limited to this. The automatic transmission 24 may be a synchronous mesh type parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt type continuously variable transmission, or the like.

In addition, in the above-mentioned embodiment, the torque converter 22 is used as the fluid transmission device, but this is not limited to the embodiment. For example, instead of the torque converter 22, other fluid transmission devices such as a fluid coupling that does not have a torque amplifying effect may be used as the fluid transmission device. Alternatively, the fluid transmission device does not necessarily have to be provided, and may be replaced with, for example, a starting clutch.

Note that the above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

10: Vehicle 12: Engine 14: Drive wheels 20: K0 clutch (clutch)
56: Hydraulic control circuit 90: Electronic control device (control device)
92b: Motor control unit 92c: Start control unit 94: Clutch control unit 98: Learning control unit 120: Clutch actuator MG: Electric motor

Claims (1)

A control device for a vehicle including an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to be capable of transmitting power, a clutch whose control state is switched by controlling a hydraulic clutch actuator provided between the engine and the electric motor in the power transmission path, and a hydraulic control circuit that supplies a regulated hydraulic pressure to the clutch actuator,
a start control unit that controls the electric motor so as to increase an output torque of the electric motor by a necessary cranking torque, which is a torque necessary for cranking the engine, when starting the engine, and also controls the engine so as to start operation of the engine;
a clutch control unit that outputs, as a hydraulic pressure command value for supplying the hydraulic pressure during an engagement transition in which a control state of the clutch is switched from a released state to an engaged state, to the hydraulic control circuit, a cranking hydraulic pressure command value that adjusts the hydraulic pressure to the clutch actuator so that the clutch transmits the required cranking torque, and outputs, prior to the output of the cranking hydraulic pressure command value, to the hydraulic control circuit, as the hydraulic pressure command value, a rapid filling hydraulic pressure command value that improves responsiveness of the hydraulic pressure to the clutch actuator so that the clutch is quickly brought to a packing completion state in which a pack clearance of the clutch is closed;
an electric motor control unit that, when the engine is stopped and the vehicle is in a predetermined state in which the predetermined torque is unnecessary under a condition in which the electric motor is caused to output a predetermined torque that causes a creep phenomenon, executes a torque cut control that prevents the electric motor from outputting the predetermined torque, and, when the engine is started during execution of the torque cut control, releases the torque cut control;
a learning control unit that performs learning control to correct a relationship that represents a correlation between the hydraulic pressure during the engagement transition of the clutch and the hydraulic pressure command value;
Contains
a clutch control unit that, when the engine is started while the torque cut control is being executed, waits to output the rapid fill hydraulic pressure command value until a predetermined time has elapsed during which the specified torque is stably output after the torque cut control is started to be released.

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