Vehicle control device

Abstract

To suppress a shock when starting an engine, and suppress deterioration of acceleration response in motor traveling by an electric motor.SOLUTION: Since slip control is performed before the start of an engine during motor traveling, the start of the engine can be quickly performed, and a shock due to torque fluctuation accompanying the start of the engine can be suppressed. In addition, when input torque to a second clutch is lower than a torque capacity at the time of controlling the second clutch to be in a packing completion state during the motor traveling, the slip control is stopped, so that the torque capacity of the second clutch is easily increased even when an acceleration request is made in a state where the input torque to the second clutch is reduced. Therefore, it is possible to suppress a shock at the time of starting the engine and suppress deterioration of the acceleration response at the time of motor traveling by an electric motor.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle provided with a clutch between an engine, an electric motor, and drive wheels.

Background Art

[0002] A control device for a vehicle including an engine, an electric motor power-transmissibly connected to a power transmission path between the engine and drive wheels, a first clutch provided between the engine and the electric motor in the power transmission path, and a second clutch provided between the electric motor and the drive wheels in the power transmission path is well known. For example, the control device for a vehicle described in Patent Document 1 is such a device. In this Patent Document 1, when starting the engine by controlling the first clutch toward the engaged state during motor running in which only the electric motor is used as a power source in the released state of the first clutch and the engaged state of the second clutch, it is disclosed that the second clutch is set in a slip state or a released state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when starting the engine during motor driving, for example, from the viewpoints of suppressing starting shock and improving response, it is conceivable to control the second clutch to a slip state before starting the engine. By the way, when the second clutch is controlled to a slip state during motor driving, if the input torque to the second clutch is low, there may be a need to set the pack clearance of the second clutch to an uncompressed state. When accelerating the vehicle from such a state, the torque capacity of the second clutch cannot be increased unless the second clutch is in a fully compressed state where the pack clearance is compressed. Then, although it is originally motor driving using an electric motor with better responsiveness than the engine, there is a risk of deterioration in acceleration response.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a vehicle control device capable of suppressing shock when starting the engine and suppressing deterioration in acceleration response during motor driving by an electric motor.

Means for Solving the Problems

[0006] The gist of the first invention is as follows: (a) a control device for a vehicle comprising an engine, an electric motor connected to be power-transmittable to a power transmission path between the engine and drive wheels, a first clutch provided between the engine and the electric motor in the power transmission path, and a second clutch provided between the electric motor and the drive wheels in the power transmission path, (b) switching from motor running in which only the electric motor is used as a power source in a released state of the first clutch to engine running in which at least the engine is used as a power source in an engaged state of the first clutch is executed in a state where slip control for making the second clutch in a slip state is being performed, (c) during motor running, the slip control is performed from before starting the engine along with the switching to engine running, and when the input torque to the second clutch during motor running is lower than the torque capacity when controlling to make the second clutch in a packed state where the pack clearance is filled, the slip control is stopped.

Advantages of the Invention

[0007] According to the first invention, during motor running, since slip control is performed from before starting the engine, the engine can be started promptly, and shock due to torque fluctuation accompanying the start of the engine can be suppressed. In addition, when the input torque to the second clutch during motor running is lower than the torque capacity when controlling to make the second clutch in a packed state, the slip control is stopped, so even if an acceleration request is made from a state where the input torque to the second clutch has decreased, the torque capacity of the second clutch can be easily increased. Therefore, shock can be suppressed when starting the engine, and deterioration of acceleration response during motor running by the electric motor can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Examples

[0010] FIG. 1 is a diagram for explaining the schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining the control functions and the main parts of the control system for various controls in the vehicle 10. In FIG. 1, the vehicle 10 is a hybrid vehicle including an engine 12 and an electric motor MG that function as power sources. Further, the vehicle 10 includes drive wheels 14 and a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14.

[0011] The engine 12 is a known internal combustion engine. The engine 12 is controlled by an engine control device 50 provided in the vehicle 10 by an electronic control device 90 described later, and the engine torque Te, which is the torque of the engine 12, is controlled.

[0012] The electric motor MG is a known rotary electric machine having a function as a motor that generates mechanical power from electric power and a function as a generator that generates 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 has its torque, i.e., the MG torque Tm, controlled by the inverter 52 being controlled by an electronic control unit 90 described later. The MG torque Tm is, for example, a power running torque as a positive torque on the acceleration side that generates power by the electric power from the battery 54 when the rotation direction of the electric motor MG is the normal rotation direction that is the same as the operation direction of the engine 12. The MG torque Tm is, for example, a regenerative torque as a negative torque on the deceleration side that generates electricity by the power of the engine 12 or the driven force input from the drive wheel 14 side when the rotation direction is the normal rotation. The electric power is also the same as electric energy unless otherwise distinguished. The power is also the same as driving force, torque, and force unless otherwise distinguished.

[0013] The power transmission device 16 includes a disconnect clutch K0, a launch clutch WSC, an automatic transmission 20, a reduction gear mechanism 22, a differential gear 24 connected to the reduction gear mechanism 22, etc. in a case 18 which is a non-rotating member attached to the vehicle body. The disconnect clutch K0 is a first 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 launch clutch WSC is a second clutch provided between the electric motor MG and the drive wheels 14 in the power transmission path between the engine 12 and the drive wheels 14. The reduction gear mechanism 22 is connected to a transmission output gear 26 which is an output rotating member of the automatic transmission 20.

[0014] Further, the power transmission device 16 includes a pair of drive shafts 28 and the like connected to the differential gear 24. Further, the power transmission device 16 includes an engine connecting shaft 30 that connects the engine 12 and the engagement / disengagement clutch K0, a motor connecting shaft 32 that connects the engagement / disengagement clutch K0 and the starting clutch WSC, and the like within the case 18. Further, the power transmission device 16 includes a mechanical oil pump 34, a transmission member 36 that connects the motor connecting shaft 32 and the mechanical oil pump 34, and the like within the case 18. The transmission member 36 is composed of, for example, a sprocket and a chain. The mechanical oil pump 34 is driven by a power source (engine 12, motor MG) and discharges the hydraulic oil OIL used in the power transmission device 16.

[0015] The motor MG is connected to the motor connecting shaft 32 within the case 18 so as to be capable of transmitting power. That is, the motor MG is connected to the power transmission path between the engine 12 and the drive wheels 14 so as to be capable of transmitting power.

[0016] The engagement / disengagement clutch K0 is, for example, a known friction engagement device. The engagement / disengagement clutch K0 has its control state, that is, its operating state such as the engaged state, the slip state, and the released state switched by changing the K0 torque capacity Tk0, which is the torque capacity of the engagement / disengagement clutch K0, by the regulated K0 hydraulic pressure PRk0 supplied from the hydraulic control circuit 56 provided in the vehicle 10.

[0017] The starting clutch WSC is a wet friction engagement device composed of, for example, a multi-plate clutch pressed by an actuator. The control state of the starting clutch WSC is switched by changing the WSC torque capacity Twsc, which is the torque capacity of the starting clutch WSC, by the regulated hydraulic pressure PRwsc supplied from the hydraulic control circuit 56.

[0018] The input side member of the starting clutch WSC is integrally connected to the motor connecting shaft 32. The output side member of the starting clutch WSC is integrally connected to the transmission input shaft 38, which is the input rotating member of the automatic transmission 20.

[0019] FIG. 2 is a partial cross-sectional view showing an example of a starting clutch WSC. In FIG. 2, the starting clutch WSC includes a clutch drum 100, a clutch hub 102, a separator plate 104, a friction plate 106, a piston 108, a return spring 110, a spring receiving plate 112, and a snap ring 114. The clutch drum 100 and the clutch hub 102 are provided on the same axis CS. In FIG. 2, the radially outer peripheral portion of the starting clutch WSC in the upper half of the axis CS is shown. The axis CS is an axis such as the motor connecting shaft 32 and the transmission input shaft 38. The clutch drum 100 is connected to, for example, the transmission input shaft 38. The clutch hub 102 is connected to, for example, the motor connecting shaft 32. The separator plate 104 has a plurality of substantially annular plate-like outer peripheral edges spline-fitted to the inner peripheral surface of the cylindrical portion 100a of the clutch drum 100. The friction plate 106 is interposed between a plurality of separator plates 104, and a plurality of substantially annular plate-like inner peripheral edges are spline-fitted to the outer peripheral surface of the clutch hub 102. The piston 108 has a pressing portion 108a extending in the direction of the separator plate 104 provided on the outer peripheral edge. The return spring 110 is interposed between the piston 108 and the spring receiving plate 112, and biases a part of the piston 108 to abut against the bottom plate portion 100b of the clutch drum 100. An oil chamber 116 is formed between the piston 108 and the bottom plate portion 100b of the clutch drum 100 in the starting clutch WSC. An oil passage 118 communicating with the oil chamber 116 is formed in the clutch drum 100. In the starting clutch WSC, a clutch actuator 120 as a hydraulic actuator is constituted by the clutch drum 100, the piston 108, the return spring 110, the spring receiving plate 112, the oil chamber 116, etc.

[0020] In the starting clutch WSC, when the WSC hydraulic pressure PRwsc is supplied from the hydraulic control circuit 56 to the oil chamber 116 through the oil passage 118, the piston 108 moves in the direction of the separator plate 104 against the biasing force of the return spring 110 by the WSC hydraulic pressure PRwsc. When the pressing portion 108a of the piston 108 presses the separator plate 104 and the friction plate 106, the starting clutch WSC is switched to the engaged state. The control state of the starting clutch WSC is switched by changing the WSC torque capacity Twsc by the WSC hydraulic pressure PRwsc.

[0021] In the starting clutch WSC, when the oil chamber 116 is filled with the working oil OIL and the clearance between the separator plate 104 and the friction plate 106 is filled by the pressing force of the piston 108 (=PRwsc × piston pressure receiving area) against the biasing force of the return spring 110, that is, when the pack clearance of the starting clutch WSC is filled, it is in a so-called complete pack state. When the WSC hydraulic pressure PRwsc is further increased from the complete pack state of the starting clutch WSC, the WSC torque capacity Twsc is generated. That is, the complete pack state of the starting clutch WSC is a state where the starting clutch WSC starts to have a torque capacity, that is, a state where the WSC torque capacity Twsc starts to be generated, if the WSC hydraulic pressure PRwsc is increased from that complete pack state. The WSC hydraulic pressure PRwsc for achieving the complete pack state is the WSC hydraulic pressure PRwsc for the state where the piston 108 reaches the stroke end and the WSC torque capacity Twsc is not generated, that is, the pack stroke end (=PSE) pressure PRpse. In this embodiment, the WSC torque capacity Twsc when the WSC hydraulic pressure PRwsc is the PSE pressure PRpse is referred to as the PSE torque Tpse.

[0022] FIG. 3 is a diagram showing an example of PT characteristics which is the relationship between the WSC hydraulic pressure PRwsc and the WSC torque capacity Twsc in the starting clutch WSC. In FIG. 3, when the WSC hydraulic pressure PRwsc is equal to or higher than the PSE pressure PRpse, the WSC torque capacity Twsc is increased in proportion to the WSC hydraulic pressure PRwsc. Also, since the starting clutch WSC is a wet friction engagement device, in the stroke back region where the WSC hydraulic pressure PRwsc is equal to or lower than the PSE pressure PRpse, a WSC torque capacity Twsc corresponding to the sliding loss (the sliding torque is also the same) between the separator plate 104 and the friction plate 106 is generated.

[0023] The automatic transmission 20 is a known planetary gear type automatic transmission including, for example, a planetary gear device and an engagement device CB. The engagement device CB includes, for example, a plurality of known friction engagement devices. Each of the engagement devices CB has its control state switched by changing the CB torque capacity Tcb, which is its respective torque capacity, by means of the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56.

[0024] The automatic transmission 20 forms any one of a plurality of shift stages having different gear ratios γat (= input rotational speed Ni / output rotational speed No) when any one of the engagement devices of the engagement device CB is engaged. The input rotational speed Ni is the rotational speed of the transmission input shaft 38 and is the input rotational speed of the automatic transmission 20. The input rotational speed Ni is also the rotational speed of the output side member of the starting clutch WSC. The output rotational speed No is the rotational speed of the transmission output gear 26 and is the output rotational speed of the automatic transmission 20.

[0025] The hydraulic oil OIL discharged by at least one of the mechanical oil pump 34 and the electric oil pump 58 driven by the pump motor 60 provided in the vehicle 10 is supplied to the hydraulic control circuit 56.

[0026] Vehicle 10 further includes an electronic control unit 90 as a controller that includes a control device for the vehicle 10. The electronic control unit 90 is configured to include a so-called microcomputer including, for example, a CPU, a RAM, a ROM, an input / output interface, etc., and executes various controls for the vehicle 10.

[0027] Various signals etc. (for example, engine rotation speed Ne which is the rotation speed of the engine 12, MG rotation speed Nm which is the rotation speed of the electric motor MG and also the rotation speed of the input side member of the launch clutch WSC, input rotation speed Ni, output rotation speed No corresponding to the vehicle speed V, accelerator opening θacc, throttle valve opening θth, brake-on signal Bon, battery temperature THbat, battery charge / discharge current Ibat, battery voltage Vbat, operating oil temperature THoil which is the temperature of the operating oil OIL, etc.) based on the detection values by various sensors 70, 72, 74, 76, 78, 80, 82, 84, 86, etc. provided in the vehicle 10 are respectively supplied to the electronic control unit 90.

[0028] Various command signals etc. (for example, engine control command signal Se, MG control command signal Sm, CB hydraulic pressure control command signal Scb, K0 hydraulic pressure control command signal Sk0, WSC hydraulic pressure control command signal Swsc, electric oil pump control command signal Seop, etc.) are respectively output from the electronic control unit 90 to various devices 50, 52, 56, 60, etc. provided in the vehicle 10.

[0029] The electronic control unit 90 includes a power source control means, that is, a power source control section 92, and a clutch control means, that is, a clutch control section 94, in order to realize various controls in the vehicle 10.

[0030] The power source control section 92 includes a function of controlling the operation of the engine 12 and a function of controlling the operation of the electric motor MG, and executes hybrid drive control etc. by the engine 12 and the electric motor MG by those control functions.

[0031] The power source control unit 92 calculates the driving demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a relationship for obtaining the driving demand amount that has been experimentally or designedly obtained and stored in advance, that is, determined in advance. The driving demand amount is, for example, the required driving torque Trdem [Nm] at the driving wheels 14. The required driving torque Trdem is, in other words, the required driving power Prdem [W] at the vehicle speed V at that time. As the driving demand amount, the required driving force Frdem [N] at the driving wheels 14 or the like can also be used. The power source 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 motor MG so as to realize the required driving power Prdem in consideration of transmission losses, auxiliary load, the gear ratio γat of the automatic transmission 20, etc.

[0032] When the power source control unit 92 can cover the required driving power Prdem only with the output of the motor MG, the driving mode for driving the vehicle 10 is set to the BEV driving mode. The BEV driving mode is a motor driving mode in which motor running (= BEV running) is possible using only the motor MG as the power source in the released state of the disconnect clutch K0. On the other hand, when the power source control unit 92 cannot cover the required driving power Prdem without using at least the output of the engine 12, the driving mode is set to the engine driving mode, that is, the HEV driving mode. The HEV driving mode is a hybrid driving mode in which engine running, that is, hybrid running (= HEV running), is possible using at least the engine 12 as the power source in the engaged state of the disconnect clutch K0. On the other hand, even when the power source control unit 92 can cover the required driving power Prdem only with the output of the motor MG, when the battery 54 needs to be charged or when the engine 12 or the like needs to be warmed up, the HEV driving mode is established.

[0033] The power source control unit 92 determines whether there is an engine start request to switch the control state of the engine 12 from the stopped state to the operating state. For example, in the BEV driving mode, the power source control unit 92 determines whether there is an engine start request based on whether the required driving power Prdem has increased beyond the range that can be covered only by the output of the motor MG, whether warm-up of the engine 12 etc. is necessary, whether charging of the battery 54 is necessary, and so on.

[0034] When the clutch control unit 94 determines that there is an engine start request by the power source control unit 92, the clutch control unit 94 controls the engagement / disengagement clutch K0 so as to execute the start control of the engine 12. For example, the clutch control unit 94 outputs a K0 hydraulic pressure control command signal Sk0 for controlling the disengaged engagement / disengagement clutch K0 toward the engaged state so that the K0 torque capacity Tk0 for transmitting the cranking torque Tcr to the engine 12 side is obtained. The cranking torque Tcr is a predetermined torque required for cranking the engine 12 to raise the engine rotational speed Ne.

[0035] When the power source control unit 92 determines that there is an engine start request, the power source control unit 92 controls the engine 12 and the motor MG so as to execute the start control of the engine 12. For example, the power source control unit 92 outputs an MG control command signal Sm for the motor MG to output the cranking torque Tcr in accordance with the switching of the engagement / disengagement clutch K0 by the clutch control unit 94 to the engaged state. Further, the power source control unit 92 outputs an engine control command signal Se for starting fuel supply, engine ignition, etc. in conjunction with the cranking of the engine 12.

[0036] The clutch control unit 94 performs a shift determination of the automatic transmission 20 using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic pressure control command signal Scb for switching the shift stage of the automatic transmission 20 as necessary. The shift map has a shift line for determining the shift of the automatic transmission 20 on a two-dimensional coordinate with, for example, the vehicle speed V and the required driving torque Trdem as variables, and is a predetermined relationship.

[0037] Here, the power source control unit 92 executes the switching from BEV driving to HEV driving while the slip control CNslp of the starting clutch WSC is being performed. The slip control CNslp is control that puts the starting clutch WSC in a slip state. Thereby, starting shock due to torque fluctuations associated with the starting control of the engine 12 can be suppressed. The starting shock is caused by, for example, control errors of the engine torque Te at the time of half-engagement, synchronization, and after synchronization of the disengagement / engagement clutch K0.

[0038] The clutch control unit 94 controls the starting clutch WSC with a WSC torque capacity Twsc corresponding to the WSC input torque Tinw that realizes the required driving torque Trdem for the vehicle 10 during the execution of the slip control CNslp. That is, the clutch control unit 94 controls the starting clutch WSC so that a WSC torque capacity Twsc equivalent to the WSC input torque Tinw that realizes the required driving torque Trdem is obtained during the execution of the slip control CNslp, that is, controls the WSC hydraulic pressure PRwsc (see FIG. 3). The WSC input torque Tinw is the input torque to the starting clutch WSC. The WSC input torque Tinw that realizes the required driving torque Trdem is, for example, the torque obtained by converting the required driving torque Trdem onto the motor connection shaft 32 in consideration of losses and the like, that is, the WSC required torque.

[0039] The power source control unit 92 performs the slip control CNslp by increasing a predetermined amount of the MG power Pm, which is the output of the motor MG that realizes the required driving power Prdem, in a state where the starting clutch WSC is controlled so as to have a WSC torque capacity Twsc equivalent to the WSC required torque. The increase in the MG power Pm is consumed by putting the starting clutch WSC in a slip state, but the MG power Pm that realizes the required driving power Prdem is transmitted to the drive wheels 14.

[0040] When it is determined that there is an engine start request, it is preferable to promptly shift to HEV running. Therefore, during BEV running, the power source control unit 92 performs slip control CNslp from before starting the engine 12 along with the switch to HEV running. That is, during BEV running, the power source control unit 92 performs slip control CNslp in preparation for starting the engine 12. In this embodiment, the slip control CNslp performed during BEV running is referred to as BEV-time WSC slip control CNslpev.

[0041] When the power source control unit 92 executes BEV-time WSC slip control CNslpev, for example, it sets a target MG rotation speed Nmtgt which is a target value of the MG rotation speed Nm, and controls the MG power Pm by feedback control so that the MG rotation speed Nm becomes the target MG rotation speed Nmtgt. The target MG rotation speed Nmtgt is a value (=ΔNwsctgt + Ni) obtained by adding the input rotation speed Ni to a predetermined WSC target difference rotation speed ΔNwsctgt. The WSC target difference rotation speed ΔNwsctgt is a target value of the WSC difference rotation speed ΔNwsc. The WSC difference rotation speed ΔNwsc is the difference rotation speed of the starting clutch WSC, and is the slip amount which is the rotation speed difference between the input rotation speed and the output rotation speed of the starting clutch WSC. The WSC target difference rotation speed ΔNwsctgt is the target slip amount. The input rotation speed of the starting clutch WSC is the rotation speed of the input-side member of the starting clutch WSC, and is the same value as the MG rotation speed Nm. The output rotation speed of the starting clutch WSC is the rotation speed of the output-side member of the starting clutch WSC, and is the same value as the input rotation speed Ni. That is, the WSC difference rotation speed ΔNwsc is the rotation speed difference between the MG rotation speed Nm and the input rotation speed Ni. In this embodiment, the value obtained by subtracting the input rotation speed Ni from the MG rotation speed Nm is defined as the WSC difference rotation speed ΔNwsc (=Nm - Ni).

[0042] Thus, in a state where the slip control CNslp controls the launch clutch WSC with a WSC torque capacity Twsc corresponding to the WSC input torque Tinw that realizes the required drive torque Trdem, the rotational speed control CNmg controls the MG power Pm so that the WSC differential rotational speed ΔNwsc becomes the WSC target differential rotational speed ΔNwsctgt.

[0043] By the way, during the execution of the BEV-time WSC slip control CNslpev, when the WSC input torque Tinw is low, for example, during creep running, in order to reduce the dragging torque in the launch clutch WSC, it is necessary to move the piston 108 to the initial position side by the biasing force of the return spring 110. The initial position of the piston 108 is the position of the piston 108 when the WSC hydraulic pressure PRwsc is a zero value. Note that the WSC hydraulic pressure PRwsc is not set to a zero value, but a predetermined pressure is applied, and the oil passage 118 and the oil chamber 116 are filled with the working oil OIL. The above-mentioned creep running is a running that causes a creep phenomenon in which the vehicle 10 moves slowly when, for example, the brake-off operation is performed with the accelerator off.

[0044] When an acceleration request is made from a running state in which the WSC input torque Tinw is lowered as described above, the launch clutch WSC cannot transmit sufficient torque unless the piston 108 is moved in a direction to increase the WSC torque capacity Twsc, that is, unless the launch clutch WSC is in a fully packed state. Therefore, a wasted time occurs while the piston 108 is moving. Then, although the BEV running is originally performed using the motor MG, which is said to have better responsiveness than the engine 12, there is a possibility that the acceleration may not be felt good. Thus, when the BEV-time WSC slip control CNslpev is executed, there is a risk of causing an acceleration response delay, that is, deterioration of the acceleration response.

[0045] Therefore, when the input torque Tinw of the WSC is greater than the PSE torque Tpse, which is the WSC torque capacity Twsc when the power source control unit 92 controls the starting clutch WSC to be in the fully packed state, the BEV-time WSC slip control CNslpev (the rotation speed control CNmg also agrees) is executed. When the input torque Tinw of the WSC is less than the PSE torque Tpse, the BEV-time WSC slip control CNslpev is not executed (see Fig. 3). That is, when the input torque Tinw of the WSC is lower than the PSE torque Tpse during BEV driving, the BEV-time WSC slip control CNslpev is stopped.

[0046] Also, in order to suppress or eliminate the waste time while the piston 108 is moving so that the starting clutch WSC changes from the released state to the fully packed state, it is preferable to prevent or suppress the piston 108 from being moved in the direction of releasing the starting clutch WSC by the biasing force of the return spring 110 from the position of the fully packed state. Therefore, the power source control unit 92 controls the starting clutch WSC with the PSE torque Tpse as the lower limit value of the WSC torque capacity Twsc. That is, even when the input torque Tinw of the WSC is lower than the PSE torque Tpse, the indicated value of the WSC hydraulic pressure PRwsc when controlling the starting clutch WSC is not reduced below the PSE pressure PRpse.

[0047] During BEV driving, the starting clutch WSC is switched between the engaged state and the slip state with the PSE torque Tpse as the boundary. Therefore, there is concern about the engagement shock when the starting clutch WSC is in the engaged state, or the release shock when the starting clutch WSC is in the slip state. In contrast, the WSC target differential rotation speed ΔNwsctgt in the BEV-time WSC slip control CNslpev is changed according to the input torque Tinw of the WSC. For example, the smaller the input torque Tinw of the WSC, the smaller the WSC target differential rotation speed ΔNwsctgt is set. That is, the closer the input torque Tinw of the WSC is to the PSE torque Tpse, the closer the WSC target differential rotation speed ΔNwsctgt is to the zero value.

[0048] FIG. 4 is a diagram showing a predetermined relationship between the WSC input torque Tinw and the WSC target differential rotational speed ΔNwsctgt. In FIG. 4, the WSC target differential rotational speed ΔNwsctgt is set to a smaller value as the WSC input torque Tinw is smaller. When executing the BEV-time WSC slip control CNslpev, the power source control unit 92 calculates the WSC target differential rotational speed ΔNwsctgt by applying the WSC input torque Tinw to the relationship in FIG. 4, for example, and sets the target MG rotational speed Nmtgt.

[0049] FIG. 5 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for suppressing shock at the start of the engine 12 and suppressing deterioration of the acceleration response during BEV travel, and is repeatedly executed, for example, during BEV travel.

[0050] In FIG. 5, each step of the flowchart corresponds to the function of the power source control unit 92. In step (hereinafter, steps are omitted) S10, it is determined whether or not the WSC input torque Tinw is less than the PSE torque Tpse. When the determination in S10 is negative, in S20, it is determined whether or not the WSC input torque Tinw exceeds “PSE torque Tpse + α”. “α” is the hysteresis provided in the determination of whether or not to execute the BEV-time WSC slip control CNslpev, that is, the rotational speed control CNmg. When the determination in S10 is affirmative, in S30, the rotational speed control CNmg is terminated. When the determination in S20 is affirmative, in S40, the rotational speed control CNmg is activated. When the determination in S20 is negative, this routine is terminated. As is clear from the flowchart of FIG. 5, the rotational speed control CNmg may be repeatedly activated and deactivated, and terminating the rotational speed control CNmg is the same as stopping the rotational speed control CNmg or deactivating it.

[0051] As described above, according to this embodiment, since the WSC slip control CNslpev is performed during BEV operation, the engine 12 can be started promptly, and the starting shock of the engine 12 can be suppressed. In addition, when the WSC input torque Tinw is lower than the PSE torque Tpse during BEV running, the WSC slip control CNslpev during BEV is stopped, so that even if an acceleration request is made from a state where the WSC input torque Tinw is decreasing, the WSC torque capacity Twsc can be easily increased. Therefore, it is possible to suppress the shock when starting the engine 12 and suppress the deterioration of the acceleration response during BEV running.

[0052] Further, according to this embodiment, the WSC slip control CNslpev during BEV is a rotational speed control CNmg that controls the MG power Pm so that the WSC differential rotational speed ΔNwsc becomes the WSC target differential rotational speed ΔNwsctgt. Therefore, the starting clutch WSC is set to an appropriate target slip state. In addition, it is possible to suppress the consumption of extra power and suppress the deterioration of the durability of the starting clutch WSC.

[0053] Further, according to this embodiment, the WSC target differential rotational speed ΔNwsctgt is set to a smaller value as the WSC input torque Tinw is smaller. Therefore, at the start or end of the WSC slip control CNslpev during BEV, the WSC target differential rotational speed ΔNwsctgt is set to a zero value or a value near zero, and the release shock and engagement shock of the starting clutch WSC are suppressed.

[0054] Further, according to this embodiment, since the starting clutch WSC is controlled with the PSE torque Tpse as the lower limit value of the WSC torque capacity Twsc, it is possible to prevent or suppress the piston 108 of the starting clutch WSC from being moved in the direction of releasing the starting clutch WSC by the return spring 110. In addition, the WSC torque capacity Twsc can be rapidly increased when an acceleration request is made.

[0055] As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is also applicable in other aspects.

[0056] For example, in the above-described embodiment, as the second clutch provided between the motor MG and the drive wheels 14 in the power transmission path between the engine 12 and the drive wheels 14, the starting clutch WSC was exemplified, but the present invention is not limited to this aspect. For example, as this second clutch, instead of the starting clutch WSC, an engagement device CB that can put the automatic transmission 20 in a power transmission-disabled state, that is, a neutral state, may be used. Or, when a fluid transmission device such as a torque converter is provided in the vehicle 10 instead of the starting clutch WSC, as this second clutch, a lock-up clutch provided in the fluid transmission device may be used. Incidentally, when the starting clutch WSC is used as the second clutch, the automatic transmission 20 does not necessarily have to be provided.

[0057] Further, in the above-described embodiment, when starting the engine 12 and shifting to the operating state due to a charging request of the battery 54 or the like in a state where the WSC input torque Tinw is lower than the PSE torque Tpse during BEV travel, the instructed value of the WSC hydraulic pressure PRwsc may be set lower than the PSE pressure PRpse to activate the BEV-time WSC slip control CNslpev.

[0058] Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0059] 10: Vehicle 12: Engine 14: Drive Wheels 90: Electronic Control Unit (Control Unit) K0: Disconnecting and Connecting Clutch (First Clutch) MG: Motor WSC: Starting Clutch (Second Clutch)

Claims

1. A control device for a vehicle, comprising: an engine; an electric motor connected to be power-transmittable in a power transmission path between the engine and drive wheels; a first clutch provided between the engine and the electric motor in the power transmission path; and a second clutch provided between the electric motor and the drive wheels in the power transmission path, wherein a shift from motor running in which only the electric motor is used as a power source in a released state of the first clutch to engine running in which at least the engine is used as a power source in an engaged state of the first clutch is executed in a state where slip control for setting the second clutch in a slip state is being performed, and during the motor running, the slip control is performed before starting the engine in association with the shift to the engine running, and when an input torque to the second clutch during the motor running is lower than a torque capacity when the second clutch is controlled to be in a fully-pack state where a pack clearance is filled, the slip control is stopped. The control device for a vehicle is characterized by this.

2. The slip control is rotational speed control for controlling an output of the electric motor so that a slip amount, which is a rotational speed difference between an input rotational speed and an output rotational speed of the second clutch, becomes a predetermined target slip amount in a state where the second clutch is controlled with a torque capacity corresponding to an input torque to the second clutch for realizing a required drive torque for the vehicle. The control device for a vehicle according to claim 1 is characterized by this.

3. The control device for a vehicle according to claim 2 is characterized in that the smaller the input torque to the second clutch is, the smaller the set value of the target slip amount is.

4. The control device for a vehicle according to any one of claims 1 to 3 is characterized in that a torque capacity when the second clutch is controlled to be in the fully-pack state is used as a lower limit value of the torque capacity of the second clutch to control the second clutch.

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