BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates to a control device and a control method for a vehicle.

2. Description of Related Art

[0002] In the related art, a vehicle having a clutch connected to a power transmission member and a rotary machine is known. For example, Japanese Patent Application Publication No. 2013-96555 (JP 2013-96555 A) discloses a driving device in which a second M/G can drive an output shaft at a reduced speed through a drive shaft, a second one-way clutch, a first reduction gear, and a transmission gear, and can drive the output shaft through a dog clutch and a sleeve provided in parallel to the second one-way clutch.

SUMMARY OF THE INVENTION

[0003] In a vehicle which is provided with an arbitrarily engageable and releasable clutch and a one-way clutch as a clutch connected to a power transmission member and a rotary machine, if the engagement and release of the arbitrarily engageable and releasable clutch cannot be appropriately determined, there is a possibility that degradation of drivability is caused by degradation of responsiveness or the like. There is room for improvement in controlling degradation of drivability by appropriately controlling the arbitrarily engageable and releasable clutch.

[0004] The invention provides a control device for a vehicle capable of controlling degradation of drivability by appropriately controlling an arbitrarily engageable and releasable clutch.

[0005] A first aspect of the invention is a control device for a vehicle. The vehicle includes an engine, a driving wheel, a differential mechanism connected to the engine and the driving wheel, a first rotary machine, a second rotary machine, a battery, a transmission member, a first clutch, a second clutch, and a sensor. The first rotary machine is connected to the differential mechanism and is configured to output reaction torque with respect to engine torque so as to transmit engine torque from the engine to the driving wheel through the differential mechanism. The battery is configured to transmit and receive electric power to and from the first rotary machine and the second rotary machine. The transmission member is arranged between the differential mechanism and the driving wheel. The first clutch is connected to the transmission member and the second rotary machine and is configured to be arbitrarily engaged and released. The second clutch is a one-way clutch. The one-way clutch is connected to the transmission member and the second rotary machine and is configured to permit transmission of only torque in a rotation direction to move the vehicle forward from the second rotary machine to the transmission member. The sensor is configured to detect a traveling range. The control device includes an ECU. The ECU is configured to execute at least control of the first clutch and backward movement control so as to move the vehicle backward by torque of the second rotary machine. The ECU is configured to maintain the first clutch in an engagement state when the traveling range is a backward movement range and to move the vehicle backward by torque of the second rotary machine.

[0006] In the above-described aspect, the vehicle may further include an accelerator pedal. The ECU may be configured to put the first clutch in a release state when a vehicle speed of the vehicle is in a predetermined vehicle speed range, the traveling range is a forward movement range and an accelerator is in an on state. The ECU is configured to put the first clutch in an engagement state when the vehicle speed of the vehicle is lower or higher than the predetermined vehicle speed range, the traveling range is a forward movement range and an accelerator is in an on state.

[0007] In the above-described aspect, the ECU may be configured to engage the first clutch when the accelerator is switched from the on state to an off state, the traveling range is the forward movement range and the vehicle is enabled to travel with the first clutch in the release state.

[0008] A second aspect of the invention is a control method for a vehicle. The vehicle includes an engine, a driving wheel, a differential mechanism connected to the engine and the driving wheel, a first rotary machine, a second rotary machine, a battery, a transmission member, a first clutch, a second clutch, a sensor, and an ECU. The first rotary machine is connected to the differential mechanism and is configured to output reaction torque with respect to engine torque so as to transmit engine torque from the engine to the driving wheel through the differential mechanism. The battery is configured to transmit and receive electric power to and from the first rotary machine and the second rotary machine. The transmission member is arranged between the differential mechanism and the driving wheel. The first clutch is connected to the transmission member and the second rotary machine and is configured to be arbitrarily engaged and released. The second clutch is a one-way clutch. The one-way clutch is connected to the transmission member and the second rotary machine and is configured to permit transmission of only torque in a rotation direction to move the vehicle forward from the second rotary machine to the transmission member. The sensor is configured to detect a traveling range. The control method includes executing, by the ECU, at least control of the first clutch and backward movement control so as to move the vehicle backward by torque of the second rotary machine. The control method further includes maintaining, by the ECU, the first clutch in an engagement state when the traveling range is a backward movement range and to move the vehicle backward by torque of the second rotary machine.

[0009] According to the control device and the control method for a vehicle of the invention, it is possible to suppress degradation of drivability due to degradation of responsiveness of drive force at the time of backward movement.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a flowchart showing the operation of a control device for a vehicle according to an embodiment;

FIG. 2 is a schematic configuration diagram of a vehicle according to the embodiment;

FIG 3 is a skeleton diagram of the vehicle according to the embodiment;

FIG. 4 is a block diagram of the control device for a vehicle according to the embodiment;

FIG. 5 is a time chart illustrating control by the control device for a vehicle according to the embodiment;

FIG 6 is a map showing the correspondence relationship of a vehicle speed and an accelerator opening, and release and engagement of a first clutch;

FIG 7 is another flowchart showing the operation of the control device for a vehicle according to the embodiment; and

FIG 8 is another time chart illustrating control by the control device for a vehicle according to the embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0011] Hereinafter, a control device for a vehicle according to an embodiment of the invention will be described in detail referring to the drawings. It should be noted that the invention is not limited by the embodiment. In the following embodiment, constituent elements include those which are replaceable by those skilled in the art, or those which are substantially identical thereto.

[0012] An embodiment will be described referring to FIGS. 1 to 8. This embodiment relates to a control device for a vehicle.

[0013] As shown in FIG. 2, a vehicle 1 according to the embodiment includes an engine 2, a first rotary machine MG1, a second rotary machine MG2, a battery 4, a planetary gear mechanism 10, a transmission member 11, a first clutch CLl, a second clutch CL2, a control unit 40, and an output shaft 20. The vehicle 1 is a hybrid vehicle which has the engine 2 and the two rotary machines MG1, MG2 as a power source. The vehicle 1 is a plug-in hybrid vehicle (PHV) which can be charged by an external power supply.

[0014] A vehicle control apparatus 100 of this embodiment includes the engine 2, the planetary gear mechanism 10, the first rotary machine MG1, the second rotary machine MG2, the battery 4, the transmission member 11, the first clutch CL1, the second clutch CL2, the control unit 40, and a shift position sensor 51 in the vehicle 1.

[0015] The engine 2 converts combustion energy of fuel to rotation of an output shaft 2a and outputs combustion energy. The planetary gear mechanism 10 has a function of a power distribution planetary which distributes power output from the engine 2 to the output shaft 20 side and the first rotary machine MG1 side. The first rotary machine MG1 and the second rotary machine MG2 respectively have a function as a motor (electric motor) and a function as an electric generator. The first rotary machine MG1 and the second rotary machine MG2 are connected to the battery 4 through an inverter and transmit and receive power to and from the battery 4. Electric power generated by the rotary machines MG1, MG2 can be charged in the battery 4. As the first rotary machine MG1 and the second rotary machine MG2, for example, a three-phase AC synchronous motor generator can be used.

[0016] The first clutch CL1 is a clutch device which is connected to the transmission member 11 and the second rotary machine MG2, and is arbitrarily engageable and releasable. The transmission member 11 is arranged between the planetary gear mechanism 10 and a driving wheel 25, and includes shafts and gears. In the vehicle 1 of this embodiment, an output gear 26, a driven gear 21, an output shaft 20, a drive pinion gear 22, a final gear 23, a drive shaft 24, and the like shown in FIG. 3 are included in the transmission member 11.

[0017] The second clutch CL2 is connected to the transmission member 11 and the second rotary machine MG2. The second clutch CL2 is a one-way clutch which is arranged in parallel to the first clutch CL1. That is, the first clutch CL1 and the second clutch CL2 have a parallel relationship as a transmission member of power between the transmission member 11 and the second rotary machine MG2. As the second clutch CL2, for example, a sprag one-way clutch can be used. The second clutch CL2 is a one-way clutch which permits transmission of only torque in a rotation direction to move the vehicle

I forward from the second rotary machine MG2 to the transmission member 11. That is, in terms of torque transmission from the second rotary machine MG2 toward the transmission member 11, the second clutch CL2 permits transmission of torque in the rotation direction to move the vehicle 1 forward and blocks transmission of torque in a rotation direction to move the vehicle 1 backward.

[0018] The second rotary machine G2 transmits power to the transmission member 11 through at least one of the first clutch CL1 and the second clutch CL2. Power output from the engine 2 and the second rotary machine MG2 to the transmission member

I I is transmitted to the driving wheel 25 through the output shaft 20.

[0019] The vehicle control apparatuslOO of this embodiment has a pause mode in which the rotation of the second rotary machine MG2 is stopped to enable the vehicle 1 to travel forward. In the pause mode, the first clutch CL1 is in a release state. The first clutch CL1 is released and the second rotary machine MG2 is separated from the transmission member 11, whereby the co-rotation of the second rotary machine MG2 with the rotation of the transmission member 11 is suppressed, and dragging loss or mechanical loss of the second rotary machine MG2 is reduced. Loss generated in the second rotary machine MG2 is reduced, whereby the output of the engine 2 can be reduced as much as the loss. Therefore, the vehicle control apparatuslOO of this embodiment executes the pause mode, thereby achieving loss reduction or fuel efficiency improvement of the vehicle 1.

[0020] An example of the specific configuration of the vehicle 1 will be described referring to FIG. 3. As shown in FIG 3, the output shaft 2a of the engine 2 is connected to a carrier CI of the planetary gear mechanism 10. The planetary gear mechanism 10 is an example of a differential mechanism connected to the engine 2 and the driving wheel 25, and a single pinion type planetary gear mechanism. The planetary gear mechanism 10 includes a sun gear SI, a pinion gear PI , a ring gear Rl, and a carrier CI . The planetary gear mechanism 10 is arranged between the engine 2 and the first rotary machine MGl in an axial direction. The planetary gear mechanism 10 and the first rotary machine MGl are arranged coaxially with the engine 2. The axial direction of the engine 2 matches, for example, a vehicle width direction. In the planetary gear mechanism 10, the sun gear SI is a rotation shaft connected to the first rotary machine MG1, the carrier CI is a rotation shaft connected to the engine 2, and the ring gear Rl is a rotation shaft connected to the driving wheel 25.

[0021] The first rotary machine MG1 has a rotor Rtl which is rotatably supported, and a stator Stl which is fixed to the vehicle body side. The sun gear SI is coupled to the rotor Rtl of the first rotary machine MG1 and rotates integrally with the rotor Rtl . The output gear 26 provided on the outer periphery of the ring gear Rl is in mesh with the driven gear 21. The driven gear 21 is a gear connected to the output shaft 20. The output shaft 20 is a shaft which is parallel to the output shaft 2a of the engine 2 and a rotation shaft Sh described below. The drive pinion gear 22 is connected to the output shaft 20. The drive pinion gear 22 is in mesh with the final gear 23. The final gear 23 is connected to the driving wheel 25 through the drive shaft 24. A differential gear may be provided between the final gear 23 and the drive shaft 24.

[0022] A reduction gear 31 is further in mesh with the driven gear 21. The reduction gear 31 is connected to the rotation shaft Sh. The second rotary machine MG2 is arranged coaxially with the rotation shaft Sh. The second rotary machine MG2 has a rotor Rt2 which is rotatably supported, and a stator St2 which is fixed to the vehicle body side. The rotor Rt2 is connected to the rotation shaft Sh and rotates integrally with the rotation shaft Sh. The first clutch CLl and the second clutch CL2 are respectively disposed between the rotation shaft Sh and the rotor Rt2 of the second rotary machine MG2.

[0023] The first clutch CLl of this embodiment is a gearing type dog clutch. The first clutch CLl includes a first dog tooth 32, a second dog tooth 33, a sleeve 34, and an actuator 35. The first dog tooth 32 is a dog tooth connected to the rotation shaft Sh, and is a first engagement element. The second dog tooth 33 is a dog tooth connected to the rotor Rt2 of the second rotary machine MG2, and is a second engagement element. The first dog tooth 32 and the second dog tooth 33 are, for example, teeth whose crest portion and trough portion extend linearly in the axial direction. The sleeve 34 is movably supported in the axial direction. The sleeve 34 has dog teeth corresponding to the first dog tooth 32 and the second dog tooth 33.

[0024] The actuator 35 moves the sleeve 34 in the axial direction to engage or release the first clutch CL1. The first clutch CL1 of this embodiment is a normally open type clutch, and is in a release state when the actuator 35 does not generate drive force. The actuator 35 drives the sleeve 34 toward one side (engagement direction) of the axial direction by, for example, electromagnetic force. The sleeve 34 is pressed by a pressing member, such as a return spring, in an opposite direction (release direction) to the direction of drive force by the actuator 35. Accordingly, the sleeve 34 is maintained in a release state by pressing force of the pressing member when the actuator 35 does not generate drive force.

[0025] The actuator 35 moves the sleeve 34 in the engagement direction against pressing force by drive force to be generated, and meshes the sleeve 34 with both the first dog tooth 32 and the second dog tooth 33. With this, the first dog tooth 32 and the second dog tooth 33 are engaged through the sleeve 34, and the first clutch CL1 is in an engagement state. If the first clutch CL1 is engaged, the rotation shaft Sh and the rotor Rt2 are coupled so as to be integrally rotatable through the sleeve 34. That is, the first clutch CL1 moves the sleeve 34 by the actuator 35, thereby arbitrarily engaging or releasing the first dog tooth 32 and the second dog tooth 33.

[0026] In this embodiment, of the both rotation directions of the second rotary machine MG2, the same direction as the rotation direction of the rotation shaft Sh at the time of forward traveling of the vehicle 1 is referred to as a "positive rotation direction", and a rotation direction reverse to the positive rotation direction is referred to as a "negative rotation direction" or a reverse rotation direction. Of torque of the second rotary machine MG2, torque in the positive rotation direction is referred to as "positive torque", and torque in the reverse rotation direction is referred to as "negative torque" or reverse torque. That is, positive torque is torque in the rotation direction to move the vehicle 1 forward. Negative torque is torque in the rotation direction to move the vehicle 1 backward.

[0027] The second clutch CL2 permits transmission of positive torque from the second rotary machine MG2 to the rotation shaft Sh and blocks transmission of negative torque. The second clutch CL2 permits transmission of negative torque from the rotation shaft Sh to the second rotary machine MG2 and blocks transmission of positive torque.

[0028] An oil pump 3 is connected to the output shaft 2a of the engine 2. The oil pump 3 is driven by the rotation of the engine 2 to eject oil. The oil pump 3 supplies oil to a power transmission part including the first rotary machine MGl and the second rotary machine MG2. Oil which is supplied by the oil pump 3 lubricates or cools the first rotary machine MGl and the second rotary machine MG2. The oil pump 3 may supply oil to a part to be lubricated including the planetary gear mechanism 10.

[0029] As shown in FIG. 4, the control unit 40 is an ECU including an HV ECU 50, an MG_ECU 60, and an engine ECU 70. The control unit 40 has a function of performing traveling control of the vehicle 1. The control unit 40 controls at least the first clutch CL1. Each of the ECUs 50, 60, and 70 is, for example, an electronic control unit. The HV_ECU 50 has a function of controlling the vehicle 1 in an integrated manner. The MG ECU 60 and the engine ECU 70 are electrically connected to the HV_ECU 50.

[0030] The MG_ECU 60 has a function of controlling the first rotary machine MGl and the second rotary machine MG2. The MG ECU 60 can control output torque of the first rotary machine MGl by adjusting a current value which is supplied to the first rotary machine MGl, and can control output torque of the second rotary machine MG2 by adjusting a current value which is supplied to the second rotary machine MG2. The MG ECU 60 controls inverters disposed between the first rotary machine MGl and the second rotary machine MG2, and the battery 4 to control the current values which are transmitted or received between the rotary machines MGl , MG2 and the battery 4. The MG ECU 60 of this embodiment controls the first clutch CL1. The MG_ECU 60 selectively outputs an engagement command and a release command to the first clutch CL1. The first clutch CL1 is engaged according to the engagement command output from the MG_ECU 60 and is released according to the release command. [0031] The engine ECU 70 can perform, for example, control of the opening of an electronic throttle valve of the engine 2, ignition control of the engine 2 by output of an ignition signal, injection control of fuel to the engine 2, and the like.

[0032] A vehicle speed sensor, an accelerator opening sensor, an MGl rotation speed sensor, an MG2 rotation speed sensor, an output shaft rotation speed sensor, a battery sensor, and the like are connected to the HV_ECU 50. The HV_ECU 50 can acquire a vehicle speed, an accelerator opening, a rotation speed of the first rotary machine MGl, a rotation speed of the second rotary machine MG2, a rotation speed of the output shaft 20, a battery state SOC, and the like by these sensors. A shift position sensor 51 is also connected to the HV ECU 50. The shift position sensor 51 functions as detection means for detecting a traveling range. The shift position sensor 51 of this embodiment detects a traveling range requested by a shift operation of a driver. Alternatively, the shift position sensor 51 may detect an actual traveling range of the vehicle control apparatus 100. The shift position sensor 51 is arranged in a shift lever arranged inside the vehicle 1 and detects a current operation position of the shift lever. The HV ECU 50 acquires the traveling range from the shift position sensor 51.

[0033] The HV ECU 50 calculates requested drive values, such as requested drive force, requested torque, and requested power, based on a vehicle speed and an accelerator opening. The HV_ECU 50 selects an HV traveling mode or an EV traveling mode based on the calculated requested drive values, the vehicle speed, or the like. The EV traveling mode is a traveling mode in which the second rotary machine MG2 is a power source. In the EV traveling mode, for example, the first clutch CL1 is in the engagement state. If the first clutch CL1 is in the engagement state, the second rotary machine MG2 is kept coupled to the transmission member 11. The control unit 40 causes the second rotary machine MG2 to perform powering or regenerating in the EV traveling mode.

[0034] The HV traveling mode is an engine traveling mode in which the vehicle 1 is enabled to travel with at least the engine 2 as a power source. In the HV traveling mode, the first rotary machine MGl can function as a reaction force receptacle with respect to engine torque. The first rotary machine MG1 outputs reaction torque with respect to engine torque to transmit engine torque from the engine 2 to the driving wheel 25 through the planetary gear mechanism 10. The first rotary machine MG1 outputs torque (reaction torque) in an opposite direction to the direction of engine torque, thereby causing engine torque to be output from the ring gear Rl toward the output shaft 20.

[0035] In the HV traveling mode, the HV_ECU 50 controls the first clutch CL1 in the engagement state or the release state. When the vehicle 1 is enabled to travel with the first clutch CL1 in the engagement state, the second rotary machine MG2 is kept coupled to the transmission member 11. With this, when the second rotary machine MG2 is enabled to start powering or start regenerating, torque (hereinafter, simply referred to as "MG2 torque") of the second rotary machine MG2 is transmitted to the rotation shaft Sh quickly. If the first clutch CL1 is in the engagement state, even when the second rotary machine MG2 does not perform powering or regenerating, the second rotary machine MG2 constantly rotates integrally with the rotation shaft Sh. With this, loss, such as dragging loss of the second rotary machine MG2, is generated and causes degradation of fuel efficiency.

[0036] In the HV traveling mode, when the vehicle 1 is enabled to travel with the first clutch CL1 in the release state, second rotary machine MG2 can be separated from the transmission member 11 in terms of power transmission. For example, during forward traveling, the rotation speed (hereinafter, simply referred to as "MG2 rotation speed) of the second rotary machine MG2 can be made lower than the rotation speed of the rotation shaft Sh. If the MG2 rotation speed is lower than the rotation speed of the rotation shaft Sh, the second clutch CL2 is released, and the second rotary machine MG2 is separated from the transmission member 11. With this, for example, the rotation of the second rotary machine MG2 can be stopped during traveling. Therefore, it is possible to reduce dragging loss of the second rotary machine MG2 and to achieve improvement of fuel efficiency compared to a case where the second rotary machine MG2 is co-rotated with the rotation shaft Sh.

[0037] When the second rotary machine MG2 is used as a power source in addition to the engine 2, the HV_ECU 50 makes the second rotary machine MG2 rotate forward to output positive torque. If positive torque is output to the second rotary machine MG2 in a state where the second rotary machine MG2 is separated from the transmission member 11 , the MG2 rotation speed is increased. If the MG2 rotation speed is synchronized with the rotation speed of the rotation shaft Sh, the second clutch CL2 is engaged, and positive torque is transmitted from the second rotary machine MG2 to the transmission member 11. If the MG2 rotation speed is lower than the rotation speed of the rotation shaft Sh in a state where the second clutch CL2 is engaged, the second clutch CL2 is automatically released. When decreasing the MG2 rotation speed, MG2 torque may be reduced, MG2 torque may be 0, or regenerating may be performed in the second rotary machine MG2. The second clutch CL2 is automatically engaged and released without requiring control, and does not consume power unlike the first clutch CLl. Accordingly, in the HV traveling mode, the first clutch CLl is put in the release state, making it possible to reduce in power consumption or to simplify control.

[0038] If the engagement and release of the first clutch CLl is not appropriately made, there is a possibility that drivability is degraded. For example, when moving the vehicle 1 backward, the HV ECU 50 causes the second rotary machine MG2 to output negative torque, thereby executing backward movement control to drive the vehicle 1 in the backward direction. In the vehicle control apparatus 100 of this embodiment, the second clutch CL2 blocks transmission of negative torque from the second rotary machine MG2 to the transmission member 11. Therefore, in order to output negative torque of the second rotary machine MG2 to the transmission member 11 , it is necessary to put the first clutch CLl in the engagement state.

[0039] As the control of the first clutch CLl at the time of backward movement, for example, a method which engages the first clutch CLl when drive force in the backward direction is required and releases the first clutch CLl when drive force in the backward direction is not required is considered. That is, control to engage the first clutch CLl when the accelerator pedal is depressed at the time of backward movement and to release the first clutch CLl when the accelerator pedal is released or a braking operation is performed is considered. The first clutch CLl is released while drive force in the backward direction is not required, making it possible to achieve loss reduction or the like in the second rotary machine MG2.

[0040] However, when the first clutch CLl is engaged and released according to the accelerator operation, responsiveness is likely to be degraded. For example, when the driver frequently repeats the accelerator on and the accelerator off at the time of backward movement, and the engagement and release of the first clutch CLl is frequently performed, whereby the generation of drive force is delayed with respect to the accelerator on, and drivability is likely to be degraded.

[0041] In contrast, the control unit 40 according to this embodiment maintains the first clutch CLl in the engagement state when the traveling range is a backward movement range, and enables the vehicle 1 to move backward by MG2 torque. If the traveling range detected by the shift position sensor 51 is the backward movement range, the control unit 40 selects the engagement state as the state of the first clutch CLl . For example, if the backward movement range is detected by the shift position sensor 51 when the first clutch CLl is in the release state, the control unit 40 outputs an engagement command to the first clutch CLl, and switches the first clutch CLl from the release state to the engagement state. While the backward movement range is detected, the control unit 40 maintains a state where the second rotary machine MG2 is coupled to the transmission member 11 , without putting the first clutch CLl in the release state. With this, it is possible to generate drive force in the backward direction with excellent responsiveness according to the accelerator operation of the driver, and to improve drivability. If drive force in the backward direction is required by the operation of the driver while the first clutch CLl is maintained in the engagement state, the control unit 40 causes the second rotary machine MG2 to output negative torque according to drive force, thereby moving the vehicle 1 backward by MG2 torque.

[0042] The operation of the vehicle control apparatus 100 of this embodiment will be described referring to FIG. 1. A control flow shown in FIG. 1 is repeatedly executed, for example, at a predetermined interval. In Step S10, the control unit 40 determines whether or not a shift position represents a backward movement (Rev) range. When the traveling range detected by the shift position sensor 51 is the backward movement range, the HV_ECU 50 determines to be affirmative in Step S10. When the traveling range is other than the backward movement range, for example, the forward movement range, such as a drive (D) range or a brake (B) range, a neutral (N) range, or a parking (P) range, the HV ECU 50 determines to be negative in Step S10. As a result of the determination of Step SI 0, when it is determined that the shift position is the backward movement range (Step S10-Y), the process progresses to Step S20, and otherwise (Step S10-N), this control flow ends.

[0043] In Step S20, the control unit 40 issues an engagement instruction of the first clutch CLl. The HV_ECU 50 commands the MG_ECU 60 to output the engagement instruction of the first clutch CLl. The MG ECU 60 outputs a signal of the engagement instruction to the actuator 35 of the first clutch CLl . If Step S20 is executed, the process progresses to Step S30.

[0044] In Step S30, the engagement operation in the first clutch CLl is performed. The actuator 35 of the first clutch CLl moves the sleeve 34, and meshes the sleeve 34 with the first dog tooth 32 and the second dog tooth 33, thereby coupling the rotor Rt2 of the second rotary machine MG2 and the rotation shaft Sh. If Step S30 is executed, this control flow ends.

[0045] FIG. 5 is a time chart showing an example of an operation when the control of the first clutch CLl by the control flow of FIG. 1 is performed. FIG. 5 shows an R range position flag, a vehicle speed, a first clutch on flag, an MG2 rotation speed, and an engine speed in order from above. The R range position flag is turned ON when the traveling range detected by the shift position sensor 51 is the backward movement range. The R range position flag is turned OFF when the traveling range other than the backward movement range is detected. The first clutch on flag is turned ON when it is determined that the first clutch CLl is in the engagement state. The first clutch on flag is turned OFF when it is determined that the first clutch CLl is in the release state.

[0046] In FIG. 5, the R range position flag is switched from OFF to ON in a stop state at the time tl. Accordingly, the first clutch on flag is changed from OFF to ON at the time tl, and the first clutch CL1 is engaged. The control unit 40 maintains the first clutch CL1 in the engagement state while the R range position flag is ON, and causes the second rotary machine MG2 to output torque in the reverse rotation direction according to a drive request of the driver, thereby moving the vehicle 1 backward by MG2 torque.

[0047] The R range position flag is switched from ON to OFF at the time t2. Accordingly, the first clutch on flag is changed from ON to OFF at the time t2. Thereafter, the R range position flag is OFF until the time t5. The control unit 40 determines the first clutch on flag based on a condition other than the condition of the backward movement range.

[0048] For example, the first clutch on flag is ON from the time t2 to the time t3, and the first clutch CL1 is in the engagement state, whereby forward EV traveling by MG2 torque is executed. If the vehicle 1 is stopped at the time t3, the first clutch CL1 is released. The engine 2 is started from the time t3 to the time t4, and HV traveling is started from the time t4. The control unit 40 turns ON the first clutch on flag at the time t4, puts the first clutch CL1 in the engagement state, and enables the vehicle 1 to move forward by engine torque and MG2 torque.

[0049] If the R range position flag is turned ON at the time t5, the control unit 40 turns ON the first clutch on flag to put the first clutch CL1 in the engagement state. The control unit 40 maintains the first clutch CL1 in the engagement state from the time t5 to the time t6, and enables the vehicle 1 to move backward by negative torque of the second rotary machine MG2. If the R range position flag is switched from ON to OFF at the time t6, the control unit 40 changes the first clutch on flag from ON to OFF, and puts the first clutch CL1 in the release state.

[0050] As described above, according to the vehicle control apparatus 100 of this embodiment, when the traveling range is the backward movement range, the control unit 40 maintains the first clutch CL1 in the engagement state, and enables the vehicle 1 to move backward by torque of the second rotary machine MG2. Therefore, it is possible to suppress degradation of drivability due to response delay to the accelerator operation of the driver. The control unit 40 maintains the first clutch CLl in the engagement state until the backward movement range is released, without depending on the vehicle speed or the charging state SOC of the battery 4. Therefore, even if the traveling direction is frequently changed at the time of garaging or the like, or the vehicle speed is changed during backward movement, it is not necessary to switch the engagement and release of the first clutch CLl, and it is possible to suppress degradation of drivability due to response delay.

[0051] The vehicle control apparatus 100 of this embodiment further determines the engagement and release of the first clutch CLl so as to improve drivability at the time of forward movement. Specifically, when the traveling range is the forward movement range and the accelerator is in an on state, as described below referring to FIG. 6, the control unit 40 determines the engagement and release of the first clutch CLl according to the vehicle speed.

[0052] The horizontal axis of FIG. 6 represents a vehicle speed, and the vertical axis represents an accelerator opening. In the vehicle control apparatus 100 of this embodiment, as shown in FIG. 6, a predetermined vehicle speed range Vrl is provided in a vehicle speed range on a forward side. The predetermined vehicle speed range Vrl is a vehicle speed range from a lower limit vehicle speed VI to an upper limit vehicle speed V2. When the traveling range is the forward movement range and the accelerator is in the on state, if the vehicle speed of the vehicle 1 is in the predetermined vehicle speed range Vrl, the control unit 40 puts the first clutch CLl in the release state. When the traveling range is the forward movement range and the accelerator is in the on state, if the vehicle speed of the vehicle 1 is lower or higher than the predetermined vehicle speed range Vrl, the control unit 40 puts the first clutch CLl in the engagement state. In other words, when the accelerator is in the on state, if the vehicle speed of the vehicle 1 is not in the predetermined vehicle speed range Vrl, the control unit 40 puts the first clutch CLl in the engagement state.

[0053] If the first clutch CLl is in the release state during forward traveling, it is advantageous in that loss, such as dragging loss of the second rotary machine MG2 can be reduced, and power consumption in the actuator 35 of the first clutch CLl can be reduced. Therefore, the first clutch CLl is maintained in the release state in the predetermined vehicle speed range Vrl, it is possible to achieve reduction in fuel consumption of the vehicle 1.

[0054] When the vehicle speed is lower than the predetermined vehicle speed range Vrl, if the first clutch CLl is put in the engagement state, the following advantage is obtained. When the vehicle speed is low, the second rotary machine MG2 can output torque with high efficiency, whereby in many cases, the EV traveling mode is selected. That is, even if the first clutch CLl is put in the release state, there are few situations in which an advantage of reducing dragging loss can be obtained. Instead, it is in many cases preferable to secure responsiveness when the first clutch CLl is put in the engagement state.

[0055] As described above, if the traveling range is the backward movement range, the vehicle control apparatus 100 of this embodiment maintains the first clutch CLl in the engagement state. Accordingly, the first clutch CLl is put in the engagement state in a low vehicle speed range on the forward side including a vehicle speed 0, whereby the control of the first clutch CLl is simplified. For example, when stopping at a parking position, or the like, in a situation in which forward movement and backward movement are alternately repeated, the control unit 40 can maintain the first clutch CLl in the engagement state. With this, the control is simplified and responsiveness to the accelerator operation of the driver is improved compared to a case where the engagement and release of the first clutch CLl is repeated. The lower limit vehicle speed VI is a vehicle speed which becomes a boundary between a very low vehicle speed range and a low vehicle speed range, and can be set to, for example, about 10 [km/h].

[0056] When the vehicle speed is higher than the predetermined vehicle speed range Vrl, if the first clutch CLl is put in the engagement state, the following advantage is obtained. When the vehicle speed is high, if the first clutch CLl is put in the release state, acceleration responsiveness is likely to be degraded. For example, when the first clutch CLl is in the release state, it is considered to stop the rotation of the second rotary machine MG2 or to make the MG2 rotation speed lower in order to reduce loss in the second rotary machine MG2. However, when the vehicle speed is high, if the rotation of the second rotary machine MG2 is stopped or the MG2 rotation speed is made lower, the difference in rotation speed between the MG2 rotation speed and the rotation speed of the rotation shaft Sh is increased. Accordingly, when MG2 torque is about to be output to the transmission member 11 at the time of acceleration or the like, the time required for synchronizing the MG2 rotation speed with the rotation speed of the rotation shaft Sh is extended.

[0057] In contrast, the control unit 40 of this embodiment puts the first clutch CLl in the engagement state when the vehicle speed is higher than the predetermined vehicle speed range Vrl . Therefore, degradation of responsiveness during traveling at a high vehicle speed is suppressed. The upper limit vehicle speed V2 is a vehicle speed which becomes a boundary between a medium vehicle speed range and a high vehicle speed range, and can be set to, for example, about 120 [km/h].

[0058] The control unit 40 of this embodiment engages the first clutch CLl if the accelerator is switched from on to off when the traveling range is the forward movement range and the vehicle is traveling with the first clutch CLl in the release state. As shown in FIG. 6, an engagement range Vr2 is set in a range of the accelerator off. The engagement range Vr2 is a range of the vehicle speed equal to or higher than 0, in other words, a range of the vehicle speed on the forward traveling side including stopping. In the engagement range Vr2, the first clutch CLl is engaged regardless of the vehicle speed. Accordingly, the control unit 40 engages the first clutch CLl if the accelerator is switched from on to off when the vehicle speed is in the predetermined vehicle speed range Vrl . If the accelerator is switched from on to off when the vehicle speed is lower or higher than the predetermined vehicle speed range Vrl, the engagement state of the first clutch CLl is continued. In the vehicle speed range on the forward side including stopping, while the accelerator is in the off state, the engagement state of the first clutch CLl is maintained.

[0059] If the accelerator is in the off state, the first clutch CLl is engaged, and regeneration can be performed instantly by the second rotary machine MG2. For example, the regeneration by the second rotary machine MG2 can be started quickly according to a deceleration operation, such as brake on. Therefore, according to the vehicle control apparatus 100 of this embodiment, it is possible to achieve improvement of fuel efficiency effectively using an energy recovery opportunity.

[0060] The operation of the vehicle control apparatus 100 of this embodiment will be further described referring to FIGS. 7 and 8. A control flow shown in FIG 7 is repeatedly executed, for example, at a predetermined interval. The control unit 40 may alternately execute the control flow shown in FIG 1 and the control flow shown in FIG 7.

[0061] In Step SI 10, the control unit 40 determines whether or not the shift position is the drive (D) range. In Step SI 10, it is determined whether or not the traveling range is the forward movement range. When the traveling range detected by the shift position sensor 51 is the drive (D) range, the HV_ECU 50 of the control unit 40 determines to be affirmative in Step SI 10. When the forward movement range other than the drive range, for example, the brake (B) range, is detected, the HV_ECU 50 may determine to be affirmative in Step SI 10. When the detected traveling range is a range other than the forward movement range, for example, the backward movement range, the neutral range, or the parking range, the HV ECU 50 determines to be negative in Step SI 10. As a result of the determination of Step SI 10, when it is determined that the shift position is the drive (D) range (Step S110-Y), the process progresses to Step SI 20, and otherwise (Step S110-N), this control flow ends.

[0062] In Step SI 20, the control unit 40 determines whether or not the accelerator is in the on state. The HV_ECU 50 performs the determination of Step SI 20 based on a detection result of an accelerator opening sensor. As a result of the determination of Step SI 20, when it is determined that the accelerator is in the on state (Step S120-Y), the process progresses to Step SI 30, and otherwise (Step S120-N), the process progresses to Step SHO.

[0063] In Step SI 30, the control unit 40 determines whether or not the vehicle speed is in a very low or high vehicle speed range. The HV ECU 50 performs the determination of Step SI 30 based on a detection result of a vehicle speed sensor. When the vehicle speed acquired from the vehicle speed sensor is lower or higher than the predetermined vehicle speed range Vrl, it is determined to be affirmative in Step SI 30. When the vehicle speed acquired from the vehicle speed sensor is a value within the predetermined vehicle speed range Vrl, it is determined to be negative in Step SI 30. As a result of the determination of Step SI 30, when it is determined that the vehicle speed range is very low or high (Step S130-Y), the process progresses to Step SI 40, and otherwise (Step S130-N), the process progresses to Step SI 50.

[0064] In Step SI 40, the control unit 40 determines whether or not the first clutch CLl is in the engagement state. The first clutch CLl of this embodiment is provided with a stroke sensor which detects the stroke amount of the sleeve 34. The HV ECU 50 acquires the stroke amount of the sleeve 34 from the stroke sensor and performs the determination of Step SI 40 based on the acquired stroke amount. When the stroke amount is a value representing the engagement state of the first clutch CLl, it is determined to be affirmative in Step SI 40. When the stroke amount is a value representing the release state, it is determined to be negative in Step SI 40. As a result of the determination of Step SI 40, when it is determined that the first clutch CLl is in the engagement state (Step S140-Y), this control flow ends. When it is not determined that the first clutch CLl is in the engagement state (Step S140-N), the process progresses to Step SI 60.

[0065] In Step SI 60, the control unit 40 issues the engagement instruction of the first clutch CLl . The HVJECU 50 commands the MG_ECU 60 to output the engagement instruction of the first clutch CLl. The MG ECU 60 outputs a signal of the engagement instruction to the actuator 35 of the first clutch CLl . If Step SI 60 is executed, the process progresses to Step SI 70.

[0066] In Step SI 70, the engagement operation in the first clutch CLl is performed. The actuator 35 of the first clutch CLl moves the sleeve 34, and meshes the sleeve 34 with the first dog tooth 32 and the second dog tooth 33, thereby coupling the rotor Rt2 of the second rotary machine MG2 and the rotation shaft Sh. If Step SI 70 is executed, this control flow ends.

[0067] In Step SI 50, the control unit 40 determines whether or not the first clutch CLl is in the engagement state. The HV_ECU 50 performs the determination of Step SI 50 based on a detection result of the stroke sensor. When the stroke amount acquired from the stroke sensor is a value representing the engagement state of the first clutch CLl, the HV ECU 50 determines to be affirmative in Step SI 50. When the stroke amount acquired from the stroke sensor is a value representing the release state of the first clutch, the HV_ECU 50 determines to be negative in Step SI 50. As a result of the determination of Step SI 50, when it is determined that the first clutch CLl is in the engagement state (Step S150-Y), the process progresses to Step SI 80, and otherwise (Step S150-N), this control flow ends.

[0068] In Step SI 80, the control unit 40 issues a release instruction of the first clutch CLl. The HV ECU 50 commands the MG ECU 60 to output the release instruction of the first clutch CLl. The MG ECU 60 outputs a signal of the release instruction to the actuator 35 of the first clutch CLl . If Step S 180 is executed, the process progresses to Step SI 90.

[0069] In Step SI 90, a release operation in the first clutch CLl is performed. The actuator 35 of the first clutch CLl moves the sleeve 34, and decouples the first dog tooth 32 and the second dog tooth 33. With this, the first clutch CLl is put in the release state. If Step SI 90 is executed, this control flow ends.

[0070] FIG 8 is a time chart showing an example of an operation when the control of the first clutch CLl by the control flow of FIG. 7 is performed. FIG. 8 shows a D range position flag, a vehicle speed, an accelerator on flag, a first clutch on flag, an MG2 rotation speed, and an engine speed in order from above. The D range position flag is turned ON when the traveling range detected by the shift position sensor 51 is the forward movement range. The D range position flag is turned OFF when a range other than the forward movement range is detected. The accelerator on flag is turned ON when the accelerator on is detected by the accelerator opening sensor. The accelerator on flag is turned OFF when the accelerator off is detected.

[0071] In FIG 8, forward traveling is started at the time til. Prior to the time til, the D range position flag is ON, and the forward movement range is continued. The accelerator on flag is switched from OFF to ON at the time til, and forward traveling by engine torque and MG2 torque is started. The control unit 40 turns ON the first clutch on flag at the time tl 1 to put the first clutch CL1 in the engagement state.

[0072] The accelerator on flag is changed to OFF at the time tl2. At this time, the vehicle speed is lower than the lower limit vehicle speed VI . With this, both the condition of the vehicle speed and the condition of the accelerator off are established, and the first clutch on flag is kept ON. The condition of the vehicle speed established at the time tl2 is a condition that the vehicle speed is lower than the predetermined vehicle speed range Vrl. At the time tl 3, the traveling range is the forward movement range, the accelerator is in the on state, the vehicle speed is equal to or higher than the lower limit vehicle speed VI, and the first clutch on flag is changed to OFF. Thereafter, at the time tl4, since the traveling range is the forward movement range, the accelerator is in the on state, and the vehicle speed exceeds the upper limit vehicle speed V2, the first clutch on flag is changed to ON. From the time tl 5 to the time tl6, a condition that the traveling range is the forward movement range and the accelerator is in the off state is established, and the first clutch on flag is maintained ON.

[0073] Immediately after the time tl 6, the condition that the traveling range is the forward movement range, the accelerator is in the on state, and the vehicle speed is equal to or higher than the lower limit vehicle speed VI is established, and the first clutch on flag is changed to OFF. From the time tl 7 to the time tl 8, a condition that the traveling range is the forward movement range, the accelerator is in the on state, and the vehicle speed is lower than the lower limit vehicle speed VI is established, and the first clutch on flag is turned ON. From the time tl 8 to the time tl 9, a condition that the accelerator is in the on state and the vehicle speed is in the predetermined vehicle speed range Vrl is established, and the first clutch on flag is turned OFF. From the time tl9 to the time t20, a condition that the traveling range is the forward movement range, the accelerator is in the on state, and the vehicle speed exceeds the upper limit vehicle speed V2 is established, and the first clutch on flag is turned ON. From the time t20 to the time t21, a condition that the traveling range is the forward movement range and the accelerator is in the off state is established, and the first clutch on flag is turned ON.

[0074] In periods surrounded by ellipses Ovl, Ov2 in FIG. 8, MG2 pause control to stop the second rotary machine MG2 is performed. The MG2 pause control is control to stop the rotation of the second rotary machine MG2 during traveling.

[0075] According to the vehicle control apparatus 100 of this embodiment, the engagement and release of the first clutch CL1 is controlled according to the vehicle speed at the time of forward traveling of the accelerator on. Accordingly, responsiveness to change in requested drive force is improved. When switching the engagement and release of the first clutch CL1 according to the accelerator opening or the value of the requested drive force, actual change in drive force is likely to be delayed with respect to a request of the driver as much as the time required for the engagement or release of the first clutch CL1. In contrast, according to the vehicle control apparatus 100 of this embodiment, the state of the engagement or release of the first clutch CL1 is not changed depending on the change in accelerator opening. Therefore, it is possible to change drive force with excellent responsiveness to the operation of the driver. The engagement and release of the first clutch CL1 is determined according to the vehicle speed regardless of the accelerator opening, whereby the control can be simplified.

[0076] A first modification example of the embodiment will be described. In the above-described embodiment, a prerequisite for determining the engagement and release of the first clutch CL1 according to the vehicle speed is that the traveling range is the forward movement range and the accelerator is in the on state. The above-described prerequisite may be that vehicle is during engine traveling, in other words, the HV traveling mode is executed. In this case, in the control flow of FIG. 7, as a condition for the progress to Step SI 30, a condition that the engine 2 is in operation, or during traveling by engine torque may be added.

[0077] A second modification example of the embodiment will be described. The first clutch CL1 is not limited to the illustrated gearing type clutch, and may be a friction type clutch or the like. The first clutch CL1 may be, for example, a wet or dry multiple disc clutch or the like. The actuator 35 of the first clutch CL1 may be engaged or released by hydraulic pressure or the like, instead of electromagnetic force. The second clutch CL2 is not limited to a sprag one-way clutch, and may be other types of one-way clutches. That is, the second clutch CL2 may have a function of transmitting torque in one rotation direction from one engagement element to the other engagement element and blocking transmission of torque in the other rotation direction.

[0078] The contents disclosed in the above-described embodiment and modification examples may be appropriately combined to be executed.