Vehicle drive device

A vehicle drive device includes: a brake that is provided with a plurality of friction plates, a first piston and a second piston, and a first piston hydraulic chamber and a second piston hydraulic chamber, and selectively fixes the third rotating element to a fixing member; a hydraulic control circuit that controls supply of the hydraulic pressure to the first piston hydraulic chamber and the second piston hydraulic chamber; and a control device. The control device controls the hydraulic control circuit such that the hydraulic pressure is supplied to the first piston hydraulic chamber and the second piston hydraulic chamber when the first traveling mode is set, and controls the hydraulic control circuit such that the hydraulic pressure is supplied only to one of the first piston hydraulic chamber and the second piston hydraulic chamber when the second traveling mode is set.

CR0SS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2021-032003 filed on Mar. 1, 2021, incorporated herein by reference in its entirety.

1. Technical Field

The present disclosure relates to a vehicle drive device.

2. Description of Related Art

WO 2010/141682 discloses a vehicle drive device including a first power source, a second power source, a first output shaft that is connected to the first power source and outputs power to one of front wheels and rear wheels, a second output shaft that outputs power to the other of the front wheels and the rear wheels, and a differential mechanism including a first rotating element, a second rotating element, and a third rotating element. The vehicle drive device is capable of realizing a first traveling mode in which a vehicle travels in a four-wheel drive state using at least the power output from the first power source, and a second traveling mode in which the vehicle travels in a two-wheel drive state using the power output from the second power source.

SUMMARY

In the vehicle drive device disclosed in WO 2010/141682, a brake that selectively fixes the third rotating element to a fixing member is provided. The third rotating element is provided as a reaction force element, the first rotating element is provided as an input element, and the second rotating element is provided as an output element. Then, in the first traveling mode, at least the power from the first power source is input to the first rotating element, and the third rotating element is fixed to the fixing member to decelerate the power input to the first rotating element and to output the power from the second rotating element to the first output shaft and the second output shaft. Further, in the second traveling mode, the power from the second power source is input to the first rotating element, and the third rotating element is fixed to the fixing member to decelerate the power input to the first rotating element and to output the power from the second rotating element to one of the first output shaft and the second output shaft. When the vehicle drive device is configured as described above, there is the following issue.

That is, the power input from the first drive source to the first rotating element is larger than the power input from the second drive source to the first rotating element, and in the first traveling mode, the brake needs to generate reaction torque that is larger than that in the second traveling mode. Here, when a hydraulic friction engaging device is used as the brake, the number of friction plates needs to match the large torque capacity required in the first traveling mode. However, there is an issue that, when the number of friction plates is large, the controllability of the friction engaging device deteriorates when the torque capacity required for engaging the friction engaging device is small, and as a result, a shock is generated when the friction plates are engaged to set the second traveling mode.

The present disclosure has been made in view of the above issue, and an object of the present disclosure is to provide a vehicle drive device capable of suppressing a shock when the second traveling mode is set.

In order to solve the above issue and achieve the object, a vehicle drive device according to the present disclosure includes: a first power source; a second power source; a first output shaft that is connected to the first power source and outputs power to one of front wheels and rear wheels; a second output shaft that outputs power to the other of the front wheels and the rear wheels; a differential mechanism provided with a first rotating element, a second rotating element, and a third rotating element; a control device; a brake that is provided with a plurality of friction plates, a first piston and a second piston that press the friction plates, and a first piston hydraulic chamber and a second piston hydraulic chamber for applying a hydraulic pressure to the first piston and the second piston, respectively, and selectively fixes the third rotating element to a fixing member; and a hydraulic control circuit that controls supply of the hydraulic pressure to the first piston hydraulic chamber and the second piston hydraulic chamber. A first traveling mode and a second traveling mode are configured to be settable, the first traveling mode being a mode in which at least the power from the first power source is input to the first rotating element and the third rotating element is fixed to the fixing member such that the power input to the first rotating element is decelerated and output from the second rotating element to the first output shaft and the second output shaft so as to cause a vehicle to travel in a four-wheel drive state, and the second traveling mode being a mode in which the power from the second power source is input to the first rotating element and the third rotating element is fixed to the fixing member such that the power input to the first rotating element is decelerated and output from the second rotating element to one of the first output shaft and the second output shaft so as to cause the vehicle to travel in a two-wheel drive state. The control device is configured to control the hydraulic control circuit such that the hydraulic pressure is supplied to the first piston hydraulic chamber and the second piston hydraulic chamber when the first traveling mode is set, and control the hydraulic control circuit such that the hydraulic pressure is supplied only to one of the first piston hydraulic chamber and the second piston hydraulic chamber when the second traveling mode is set.

With this configuration, in the vehicle drive device according to the present disclosure, it is possible to suppress a shock when the second traveling mode is set.

Further, in the above, the hydraulic control circuit may include a switching valve provided with a valve body of which position is switchable between a first position at which the hydraulic pressure is supplied to the first piston hydraulic chamber and the second piston hydraulic chamber and a second position at which the hydraulic pressure is supplied only to one of the first piston hydraulic chamber and the second piston hydraulic chamber, and an electromagnetic valve that switches the position of the valve body between the first position and the second position. The position of the valve body may be set to the first position when the electromagnetic valve is turned off.

With this configuration, when a failure that the electromagnetic valve is off occurs, the torque capacity of the brake can be adjusted to the torque capacity required in the first traveling mode.

Further, in the above, the control device may be configured to prohibit setting of the second traveling mode when a failure that the electromagnetic valve is off occurs.

With this configuration, it is possible to suppress the shock caused by setting the second traveling mode when the failure that the electromagnetic valve is off occurs.

Further, in the above, the control device may be configured to reduce the hydraulic pressure to be supplied to the first piston hydraulic chamber and the second piston hydraulic chamber for setting the second traveling mode when a failure that the electromagnetic valve is off occurs.

With this configuration, it is possible to suppress the shock caused by setting the second traveling mode when the failure that the electromagnetic valve is off occurs.

Further, in the above, the hydraulic control circuit may include a switching valve provided with a valve body of which position is switchable between a first position at which the hydraulic pressure is supplied to the first piston hydraulic chamber and the second piston hydraulic chamber and a second position at which the hydraulic pressure is supplied only to one of the first piston hydraulic chamber and the second piston hydraulic chamber, and an electromagnetic valve that switches a position of the valve body between the first position and the second position. The position of the valve body may be set to the second position when the electromagnetic valve is turned off.

With this configuration, when a failure that the electromagnetic valve is off occurs, the torque capacity of the brake can be adjusted to the torque capacity required in the second traveling mode.

Further, in the above, the control device may be configured to prohibit setting of the first traveling mode when a failure that the electromagnetic valve is off occurs.

With this configuration, it is possible to suppress deterioration of durability of the friction plates caused by setting the first traveling mode when the failure that the electromagnetic valve is off occurs.

Further, in the above, the control device may reduce torque output from the first power source for causing a vehicle to travel in the first traveling mode when a failure that the electromagnetic valve is off occurs.

With this configuration, it is possible to suppress deterioration of durability of the friction plates caused by setting the first traveling mode when the failure that the electromagnetic valve is off occurs.

The vehicle drive device according to the present disclosure can achieve an effect that a shock when the second traveling mode is set can be suppressed.

DETAILED DESCRIPTION OF EMBODIMENTS

First Embodiment

A first embodiment of a vehicle drive device according to the present disclosure will be described below. Note that, an applicable embodiment of the present disclosure is not limited to the present embodiment.

FIG.1is a diagram showing a schematic configuration of a vehicle1provided with a drive device10according to the first embodiment. The vehicle1includes right and left front wheels3R,3L, right and left rear wheels4R,4L, and the drive device10that transfers power from an engine2as a first power source to the right and left front wheels3R,3L and the right and left rear wheels4R,4L. This vehicle1is a four-wheel drive vehicle based on front-engine, rear-wheel-drive layout.

The drive device10includes the engine2, a compound transmission11connected to the engine2, a transfer12that is a front-rear wheel power distribution device connected to the compound transmission11, and a front propeller shaft13and a rear propeller shaft14that are both connected to the transfer12, a front-wheel differential gear mechanism15connected to the front propeller shaft13, a rear-wheel differential gear mechanism16connected to the rear propeller shaft14, right and left front wheel axles17R,17L connected to the front-wheel differential gear mechanism15, right and left rear wheel axles18R,18L connected to the rear-wheel differential gear mechanism16. Note that, when the right and left of the wheels and the wheel axles are not particularly differentiated from each other, reference signs R and L are omitted, and the terms are described as the front wheels3, the rear wheels4, the front wheel axles17, and the rear wheel axles18.

The engine2is a known internal combustion engine such as a gasoline engine or a diesel engine. In the engine2, engine torque that is the output torque from the engine2is controlled by controlling an engine control device101such as a throttle actuator, a fuel injection device, and an ignition device provided in the engine2by an electronic control device100that will be described later.

The power output from the engine2is transferred to the transfer12via the compound transmission11. Then, the power transferred to the transfer12is sequentially transferred from the transfer12to the rear wheels4via the rear propeller shaft14, the rear-wheel differential gear mechanism16, and the rear wheel axles18that constitute a power transfer path on the rear wheel side. A part of the power transferred to the transfer12is distributed to the front wheels3by the transfer12, and is transferred to the front wheels3via the front propeller shaft13, the front-wheel differential gear mechanism15, and the front wheel axles17that constitute a power transfer path on the front wheel side. Unless otherwise specified, the power has the same meaning as the torque and the force.

As shown inFIG.2, the drive device10includes the electronic control device100. The electronic control device100includes, for example, a so-called microcomputer provided with a central processing unit (CPU), a random access memory (RAM), a read-only memory (R0M), and an input and output interface. The CPU executes various controls by executing signal processing in accordance with a program stored in the R0M in advance while using a transitory storage function of the RAM.

Output signals from various sensors and switches provided in the vehicle1(for example, an engine speed sensor70, an output rotational speed sensor72, an MG1rotational speed sensor74, an MG2rotational speed sensor76, an accelerator operation amount sensor78, a throttle valve opening degree sensor80, a battery sensor82, an oil temperature sensor84, a four-wheel-drive (4WD) selection switch86, a shift position sensor88of a shift lever89, a Low selection switch90, and a Lock selection switch92) and the like are input to the electronic control device100. Further, the electronic control device100calculates a state-of-charge value S0C [%] as a value indicating a charge state of the battery based on, for example, charge and discharge current and a battery voltage of the battery that is a power storage device.

The electronic control device100outputs various command signals (for example, an engine control command signal for controlling the engine2, a rotating electric machine control command signal for controlling a first rotating electric machine MG1, a second rotating electric machine MG2, and a third rotating electric machine MGF, and a hydraulic control command signal for controlling a hydraulic pressure of a hydraulic control circuit111that controls operating states of engaging devices of the compound transmission11and engaging devices of the transfer12) to the respective devices provided in the drive device10(for example, the engine control device101, a rotating electric machine control device102, a transmission control device103, and a transfer control device104).

FIG.3is a diagram illustrating a schematic configuration of the compound transmission11according to the first embodiment. The first rotating electric machine MG1and the second rotating electric machine MG2are rotating electric machines having a function as a motor and a function as a generator, and are so-called motor generators. The first rotating electric machine MG1and the second rotating electric machine MG2function as a power source for traveling capable of generating drive torque. The first rotating electric machine MG1and the second rotating electric machine MG2are each connected to the battery (not shown) as a power storage device provided in the vehicle1via an inverter (not shown) provided in the vehicle1. The rotating electric machine control device102controls the inverter so as to control MG1torque and MG2torque that are the output torques from the first rotating electric machine MG1and the second rotating electric machine MG2, respectively. The output torque from the rotating electric machine is power running torque in the positive torque on the acceleration side and regenerative torque in the negative torque on the deceleration side. The battery is a power storage device that supplies and receives electric power to and from each of the first rotating electric machine MG1and the second rotating electric machine MG2. Therefore, the vehicle1is a hybrid vehicle.

The compound transmission11is provided with a continuously variable transmission unit20that is an electric differential unit and a stepped transmission unit22that is a mechanical transmission. The continuously variable transmission unit20and the stepped transmission unit22are disposed in series on a common axis in a transmission case110as a non-rotating member attached to a vehicle body. The continuously variable transmission unit20is directly or indirectly connected to the engine2via a damper (not shown) or the like. The stepped transmission unit22is connected to the output side of the continuously variable transmission unit20. Further, an output shaft24that is an output rotating member of the stepped transmission unit22is connected to the transfer12. In the drive device10, the power output from the engine2is transferred to the stepped transmission unit22, and is transferred from the stepped transmission unit22to the drive wheels via the transfer12and the like. Further, the continuously variable transmission unit20, the stepped transmission unit22, and the like are configured substantially symmetrically with respect to the common axis, and the lower half of the axis is omitted inFIG.1. The common axis above is the axis of the crankshaft of the engine2, a connecting shaft34, and the like.

The continuously variable transmission unit20is provided with the first rotating electric machine MG1and a differential mechanism32. The differential mechanism32is a power split mechanism that mechanically splits the power from the engine2to the first rotating electric machine MG1and an intermediate transfer member30that is an output rotating member of the continuously variable transmission unit20. The second rotating electric machine MG2is connected to the intermediate transfer member30such that power can be transferred to the second rotating electric machine MG2. The continuously variable transmission unit20is an electric differential unit in which the differential state of the differential mechanism32is controlled by controlling the operating state of the first rotating electric machine MG1. The continuously variable transmission unit20is operated as an electric continuously variable transmission in which a gear ratio that is a value of the ratio of the engine speed to an MG2rotational speed is variable. The engine speed has the same value as a rotational speed of the connecting shaft34serving as an input rotating member. The MG2rotational speed is a rotational speed of the intermediate transfer member30serving as an output rotating member.

The differential mechanism32is configured by a single pinion type planetary gear device, and includes a sun gear S0, a carrier CA0, and a ring gear R0. The engine2is connected to the carrier CA0via the connecting shaft34such that power can be transferred. The first rotating electric machine MG1is connected to the sun gear S0such that power can be transferred. The second rotating electric machine MG2is connected to the ring gear R0such that power can be transferred. In the differential mechanism32, the carrier CA0functions as an input element, the sun gear S0functions as a reaction force element, and the ring gear R0functions as an output element.

The stepped transmission unit22is a mechanical transmission unit serving as a stepped transmission constituting a part of a power transfer path between the intermediate transfer member30and the transfer12, that is, a mechanical transmission unit constituting a part of the power transfer path between the continuously variable transmission unit20and the transfer12. The intermediate transfer member30also functions as an input rotating member of the stepped transmission unit22. The stepped transmission unit22is an automatic transmission (AT) of a known planetary gear type that includes, for example, a plurality of sets of planetary gear devices composed of a first planetary gear device36and a second planetary gear device38, and a plurality of engaging devices of a clutch C1, a clutch C2, a brake B1, and a brake B2, including a one-way clutch F1. Hereinafter, the clutch C1, the clutch C2, the brake B1, and the brake B2are simply referred to as an engaging device unless specifically distinguished.

The engaging device is a hydraulic friction engaging device configured by a multi-plate or single plate clutch or brake pressed by a hydraulic actuator, a band brake tightened by the hydraulic actuator, or the like. An operating state of the engaging device is switched between operating states such as engagement and disengagement by each of hydraulic pressures as adjusted predetermined hydraulic pressures output from the hydraulic control circuit111provided in the vehicle1.

In the stepped transmission unit22, the rotating elements of the first planetary gear device36and the second planetary gear device38are partially connected to each other or each connected to the intermediate transfer member30, the transmission case110, or the output shaft24directly or indirectly via the engaging device or the one-way clutch F1. Each rotating element of the first planetary gear device36includes a sun gear S1, a carrier CA1, and a ring gear R1, and each rotating element of the second planetary gear device38includes a sun gear S2, a carrier CA2, and a ring gear R2.

The stepped transmission unit22is a stepped transmission in which any of a plurality of shift stages (also referred to as gear stages) among the gear stages having gear ratios(=AT input rotational speed/output rotational speed) that differ depending on, for example, engagement of a predetermined engaging device that is any of the engaging devices. That is, in the stepped transmission unit22, the gear stage is switched, that is, speed change is executed, by selectively engaging the engaging devices. The stepped transmission unit22is a stepped automatic transmission in which each of a plurality of gear stages is formed. In the first embodiment, the gear stage formed by the stepped transmission unit22is referred to as an AT gear stage. The AT input rotational speed is the input rotational speed of the stepped transmission unit22that is the rotational speed of the input rotating member of the stepped transmission unit22, and has the same value as the rotational speed of the intermediate transfer member30. Further, the AT input rotational speed has the same value as the MG2rotational speed that is the rotational speed of the second rotating electric machine MG2. The AT input rotational speed can be expressed by the MG2rotational speed. The output rotational speed is the rotational speed of the output shaft24that is the output rotational speed of the stepped transmission unit22, and is also the output rotational speed of the compound transmission11that is the entire transmission in which the continuously variable transmission unit20and the stepped transmission unit22are combined. The compound transmission11is a transmission constituting a part of the power transfer path between the engine2and the transfer12.

FIG.4is a diagram illustrating the relationship of the combination between the AT gear stage of the stepped transmission unit22and the operation of an engaging device CB. InFIG.4, a white circle indicates engagement, a white triangle indicates engagement as needed, and blank indicates disengagement. As shown inFIG.4, for example, the stepped transmission unit22has four forward AT gear stages from the AT first gear stage (“1st” inFIG.4) to the AT fourth gear stage (“4th” inFIG.4) and a reverse AT gear stage (“R” inFIG.4), as a plurality of the AT gear stages. The gear ratio of the AT first gear stage is the largest, and the gear ratio becomes smaller as the AT gear stage is on the higher side.

In the stepped transmission unit22, the electronic control device100selectively switches the AT gear stage formed in accordance with an operation of an accelerator pedal by a driver, a vehicle speed, or the like, that is, selectively forms the AT gear stages. For example, in shift control of the stepped transmission unit22, the shifting is executed by switching engagement of any of the engaging devices, that is, so-called clutch-to-clutch shifting is executed in which the shifting is executed by switching between engagement and disengagement of the engaging devices. In the first embodiment, for example, downshift from the AT second gear stage to the AT first gear stage is represented as a 2→1 downshift. The same applies to other upshifts and downshifts. Further, when the transfer12is set to the first drive state and the second drive state, which will be described later, the stepped transmission unit22is placed in a neutral state as the engaging element is disengaged.

Returning toFIG.3, the compound transmission11further includes a one-way clutch F0. The one-way clutch F0is a lock mechanism capable of fixing the carrier CA0so as not to rotate. That is, the one-way clutch F0is a lock mechanism capable of fixing the connecting shaft34that is connected to the crankshaft of the engine2and rotates integrally with the carrier CA0to the transmission case110. In the one-way clutch F0, one of two members capable of rotating with respect to each other is integrally connected to the connecting shaft34, and the other member is integrally connected to the transmission case110. The one-way clutch F0idles in the forward rotation direction that is the rotation direction of the engine2during operation, and automatically engages with the rotation direction opposite to that during operation of the engine2. Therefore, when the one-way clutch F0idles, the engine2is in a state of being able to rotate relative to the transmission case110. On the other hand, when the one-way clutch F0is engaged, the engine2is in a state of being not able to rotate relative to the transmission case110. That is, the engine2is fixed to the transmission case110as the one-way clutch F0is engaged. As described above, the one-way clutch F0allows the carrier CA0to rotate in the forward rotation direction that is the rotation direction during operation of the engine2, and blocks the carrier CA0from rotating in the negative rotation direction. That is, the one-way clutch F0is a lock mechanism capable of allowing the engine2to rotate in the forward rotation direction and blocks the engine2from rotating in the negative rotation direction.

In the compound transmission11, a continuously variable transmission in which the continuously variable transmission unit20and the stepped transmission unit22are disposed in series can be configured by the stepped transmission unit22in which the AT gear stages are formed and the continuously variable transmission unit20that is operated as the continuously variable transmission. Alternatively, the continuously variable transmission unit20can be caused to execute shifting in a similar manner to that of the stepped transmission. Therefore, the compound transmission11as a whole can be caused to execute shifting in a similar manner as that of the stepped transmission. That is, in the compound transmission11, the stepped transmission unit22and the continuously variable transmission unit20can be controlled such that the gear stages having different gear ratios, each of which represents the value of the ratio of the engine speed to the output rotational speed, are selectively established.

The electronic control device100executes shift determination of the stepped transmission unit22using an AT gear stage shift map as shown inFIG.5that is a predetermined relationship, for example, and executes the shift control of the stepped transmission unit22via the transmission control device103as needed. In the shift control of the stepped transmission unit22, the transmission control device103outputs, to the hydraulic control circuit111, a hydraulic control command signal for switching the engagement-disengagement state of the engaging device by each solenoid valve so as to automatically switch the AT gear stage of the stepped transmission unit22.

The AT gear stage shift map shown inFIG.5has, for example, a predetermined relationship having a shift line for determining the shifting of the stepped transmission unit22on the two-dimensional coordinates with the required drive torque calculated based on the vehicle speed and the accelerator operation amount as variables. In the AT gear stage shift map, the output rotational speed or the like may be used instead of the vehicle speed, or the required driving force, the accelerator operation amount, the throttle valve opening, or the like may be used instead of the required drive torque. In the AT gear stage shift map shown inFIG.5, the shift lines shown by the solid lines are each upshift line for determining the upshift, and the shift lines shown by the broken lines are each shift line for determining the downshift.

FIG.6is a diagram showing an example of a power source switching map used in switching control between the EV traveling mode and the engine traveling mode. In the drive device10according to the first embodiment, the EV traveling mode and the engine traveling mode are switched based on the power source switching map used in the switching control between the EV traveling mode and the engine traveling mode as shown inFIG.6. The map shown inFIG.6has a predetermined relationship having a boundary between a region in which that the vehicle travels in the engine traveling mode in which EV traveling is performed and a region in which the vehicle travels in the EV traveling mode in which engine traveling is performed on the two-dimensional coordinates with the vehicle speed and the required drive torque as variables. The boundary between the EV traveling region and the engine traveling region inFIG.6is, in other words, a switching line for switching between the EV traveling mode and the engine traveling mode.

FIG.7is a skeleton diagram schematically showing the transfer12according to the first embodiment, and is a skeleton diagram showing a case where the transfer12is in a first driving state.

The transfer12according to the first embodiment includes a transfer case120that is a non-rotating member. The transfer12includes, in the transfer case120, an input shaft61, a rear wheel side output shaft63as a first output shaft outputting power to the rear wheels4, a front wheel side output shaft62as a second output shaft outputting power to the front wheels3, and a third planetary gear device64as a differential mechanism. Further, the transfer12includes, in the transfer case120, a transfer member65that functions as an input rotating member to the front wheels3as a rotating member constituting a power transfer path for the front wheels3, a drive gear66that outputs power to the front wheel side output shaft62, a driven gear67integrally provided with the front wheel side output shaft62, and a front wheel drive chain68that connects the drive gear66and the driven gear67. Further, the transfer12includes, in the transfer case120, the third rotating electric machine MGF that functions as a second power source, a connection switching device40that switches the connection state of the rotating members, a brake BF1, and a clutch CF1.

The input shaft61is an input rotating member that inputs power from the engine2(and the first rotating electric machine MG1and the second rotating electric machine MG2) to the transfer12. The power from the engine2is transferred to the input shaft61via the compound transmission11. For example, the input shaft61is spline-fitted to the output shaft24that is an output rotating member of the compound transmission11.

The rear wheel side output shaft63is an output rotating member that outputs power from the transfer12to the rear wheels4. The rear wheel side output shaft63is a drive shaft disposed coaxially with the input shaft61and connected to the rear propeller shaft14(seeFIG.1).

The front wheel side output shaft62is an output rotating member that outputs power from the transfer12to the front wheels3. The front wheel side output shaft62is a drive shaft disposed on a different axis from the input shaft61and the rear wheel side output shaft63and connected to the front propeller shaft13(seeFIG.1). The front wheel side output shaft62rotates via the front wheel drive chain68and the driven gear67as the drive gear66rotates.

The drive gear66is connected to the transfer member65so as to rotate integrally. The transfer member65is a rotating member that transfers power to the front wheel side output shaft62. The transfer member65and the drive gear66are disposed so as to be rotatable relative to the rear wheel side output shaft63. In the transfer12, the transfer member65, the drive gear66, and the third planetary gear device64are disposed on the same rotation center as the rear wheel side output shaft63.

The third planetary gear device64is configured by a single pinion type planetary gear device including three rotating elements. As shown inFIG.7, the third planetary gear device64includes, as the three rotating elements, a sun gear S3, a carrier CA3that supports a plurality of pairs of pinion gears that mesh with each other so as to be rotatable and revolvable, and a ring gear R3that meshes with the sun gear S3via the pinion gears. The third rotating electric machine MGF that functions as the second power source is constantly connected to the sun gear S3. When the transfer12is placed in the second drive state and the sixth drive state, which will be described later, the sun gear S3functions as an input element, the ring gear R3functions as a reaction force element, and the carrier CA3functions as an output element.

A first rotating member51that can be connected to the input shaft61is connected to the sun gear S3. The first rotating member51is a member that rotates integrally with the sun gear S3and includes gear teeth51a.Further, the first rotating member51is attached with an input gear55to which power from the third rotating electric machine MGF is input. The input gear55and the first rotating member51rotate integrally.

A third rotating member53that can be connected to the rear wheel side output shaft63is connected to the carrier CA3. The third rotating member53is a member that rotates integrally with the carrier CA3and includes gear teeth53a.Further, the transfer member65is connected to the carrier CA3. The transfer member65is a member that rotates integrally with the carrier CA3.

The second rotating member52that can be connected to the rear wheel side output shaft63is connected to the ring gear R3. The second rotating member52is a member that rotates integrally with the ring gear R3and includes gear teeth52a.

The third rotating electric machine MGF is a motor generator (MG) capable of functioning as a motor and a generator. The third rotating electric machine MGF includes a rotor, a stator, and an output shaft that rotates integrally with the rotor, and is electrically connected to the battery via an inverter. As shown inFIG.7, an output gear54is provided on the output shaft of the third rotating electric machine MGF. The output gear54meshes with the input gear55, and the output gear54and the input gear55constitute a reduction gear train. Therefore, when MGF torque that is the output torque from the third rotating electric machine MGF is transferred to the input gear55, rotation of the third rotating electric machine MGF is subjected to speed change (decelerated) and transferred to the sun gear S3.

The connection switching device40is a device that selectively switches the connection destinations of the input shaft61and the rear wheel side output shaft63. In other words, the connection switching device40is a device for switching the connection state of the rotating members constituting the transfer12. Specifically, the connection switching device40selectively switches the connection destinations of the first rotating member51, the second rotating member52, and the third rotating member53that rotate integrally with each rotating element of the third planetary gear device64. As shown inFIG.7, the connection switching device40includes a first dog clutch D1and a second dog clutch D2.

The first dog clutch D1is a first disconnection-connection mechanism for switching the connection destination of the input shaft61. As shown inFIG.7, the first dog clutch D1selectively connects the input shaft61and the first rotating member51(sun gear S3) or the rear wheel side output shaft63. That is, the first dog clutch D1switches between a first input state and a second input state. In the first input state, the power from the input shaft61is transferred to the rear wheel side output shaft63without intervening the third planetary gear device64. In the second input state, the power from the input shaft61is transferred to the rear wheel side output shaft63via the third planetary gear device64.

The first dog clutch D1includes a first switching sleeve41as an input switching member. The first switching sleeve41includes first gear teeth41athat mesh with gear teeth61aof the input shaft61and second gear teeth41bthat mesh with first gear teeth63aof the rear wheel side output shaft63or the gear teeth51aof the first rotating member51. The first switching sleeve41is moved in the axial direction by the actuator of the first dog clutch D1. The first switching sleeve41is switched to any of a first input state in which the meshing target of the second gear teeth41bmesh with the first gear teeth63aof the rear wheel side output shaft63while the first gear teeth41aconstantly mesh with the gear teeth61aof the input shaft61, a disengaged state in which the second gear teeth41bdo not mesh with any of the first gear teeth63aof the rear wheel side output shaft63and the gear teeth51aof the first rotating member51, and a second input state in which the second gear teeth41bmesh with the gear teeth51aof the first rotating member51.

The second dog clutch D2is a second disconnection-connection mechanism for switching the connection destination of the rear wheel side output shaft63. The second dog clutch D2selectively connects the rear wheel side output shaft63and the second rotating member52(ring gear R3) or the third rotating member53(carrier CA3). That is, the second dog clutch D2switches between a first transfer state in which power is transferred between the rear wheel side output shaft63and the second rotating member52(ring gear R3), and a second transfer state in which power is transferred between the rear wheel side output shaft63and the third rotating member53(carrier CA3).

The second dog clutch D2includes a second switching sleeve42as a switching member. The second switching sleeve42includes first gear teeth42aand second gear teeth42b.The first gear teeth42aof the second switching sleeve42can selectively mesh with the gear teeth52aof the second rotating member52that rotates integrally with the ring gear R3and the gear teeth53aof the third rotating member53that rotates integrally with the carrier CA3. The second switching sleeve42is moved in the axial direction by the actuator of the second dog clutch D2. Then, the second switching sleeve42is switched to any of a first transfer state in which the first gear teeth42amesh with the gear teeth52aof the second rotating member52while the second gear teeth42bconstantly mesh with the second gear teeth63bof the rear wheel side output shaft63, a disengaged state in which the first gear teeth42ado not mesh with any of the gear teeth52aof the second rotating member52and the gear teeth53aof the third rotating member53, and a second transfer state in which the first gear teeth42amesh with the gear teeth53aof the third rotating member53.

The brake BF1selectively fixes the ring gear R3of the third planetary gear device64to a fixing member69. The fixing member69is the transfer case120itself or a non-rotating member integrated with the transfer case120. The transfer12is set to the high-speed side shift stage Hi when the brake BF1is disengaged, and is set to the low-speed side shift stage Lo when the brake BF1is engaged. The clutch CF1selectively connects the sun gear S3and the carrier CA3of the third planetary gear device64.

FIG.8is a diagram showing the engagement relationship of each rotating member in the transfer12according to the first embodiment. InFIG.8, the third rotating electric machine MGF is referred to as “MGF”, the sun gear S3is “S3”, the carrier CA3is “CA3”, the ring gear R3is “R3”, the brake BF1is “BF1”, the clutch CF1is “CF1”, the front wheel side output shaft62is “Fr”, and the rear wheel side output shaft63is “Rr”. Further, inFIG.8, D1(1) indicates the connection location of the first dog clutch D1in the first input state, and D1(2) indicates the connection location of the first dog clutch D1in the second input state. Further, inFIG.8, D2(1) shows the connection point of the second dog clutch D2in the first transfer state, and D2(2) shows the connection point of the second dog clutch D2in the second transfer state.

The transfer12according to the first embodiment includes the rear wheel side output shaft63, the front wheel side output shaft62, and the third planetary gear device64. The rear wheel side output shaft63is the first output shaft that is connected to the engine2(and the first rotating electric machine MG1and the second rotating electric machine MG2) as the first power source and outputs the power to the rear wheels4that are one of the front wheels3and the rear wheels4. The front wheel side output shaft62is the second output shaft that outputs the power to the front wheels3that are the other of the front wheels3and the rear wheels4. The third planetary gear device64is the differential mechanism including the sun gear S3that is the first rotating element, the carrier CA3that is the second rotating element, and the ring gear R3that is the third rotating element. Further, the transfer12according to the first embodiment includes the brake BF1that selectively fixes the ring gear R3to the fixing member69. Further, the transfer12according to the first embodiment is configured to input at least the power from the engine2that is the first power source to the sun gear S3, and fix the ring gear R3to the fixing member69to decelerate the power input to the sun gear S3and output the power from the carrier CA3to the rear wheel side output shaft63and the front wheel side output shaft62such that the vehicle can travel in the four-wheel drive state. Further, the transfer12according to the first embodiment is configured to input the power from the third rotating electric machine MGF that is the second power source to the sun gear S3, and fix the ring gear R3to the fixing member69to decelerate the power input to the sun gear S3and output the power from the carrier CA3to the front wheel side output shaft62that is one of the first output shaft and the second output shaft such that the vehicle can travel in the two-wheel drive state.

Then, the drive state of the transfer12according to the first embodiment is switched by the electronic control device100such that a first drive state, a second drive state, a third drive state, a fourth drive state, a fifth drive state, and a sixth drive state can be set.

Here, the first drive state to the sixth drive state will be described.FIG.9is a diagram showing the relationship between each of the drive states of the transfer12and an operating state of each engaging device. InFIG.9, a white circle indicates engagement, a white triangle indicates engagement as needed, and blank indicates disengagement.

The first drive state shown inFIG.7is a drive state in the EV traveling mode in which the vehicle1travels using the power from the third rotating electric machine MGF in the EV(FF)_Hi mode, and also in the two-wheel drive state in which the power from the third rotating electric machine MGF is transferred only to the front wheels3. In the first drive state, the transfer12is set to a high-speed side shift stage Hi.

When the transfer12is in the first drive state, as shown inFIG.9, the brake BF1is disengaged, the clutch CF1is engaged, the first dog clutch D1is disengaged, and the second dog clutch D2is disengaged. In the first drive state, the third planetary gear device64is in a direct connection state in which the sun gear S3and the carrier CA3are connected by the clutch CF1. In the first drive state, when the power from the third rotating electric machine MGF is transferred to the front wheel side output shaft62, the rotation of the third rotating electric machine MGF is transferred to the front wheel side output shaft62without speed change by the third planetary gear device64.

FIG.10is a skeleton diagram showing a case where the transfer12according to the first embodiment is in the second drive state. The second drive state is a drive state in the EV traveling mode in which the vehicle1travels using the power from the third rotating electric machine MGF in the EV(FF)_Lo mode, and also in the two-wheel drive state in which the power from the third rotating electric machine MGF is transferred only to the front wheels3. In the second drive state, the transfer12is set to a low-speed side shift stage Lo.

When the transfer12is in the second drive state, as shown inFIG.9, the brake BF1is engaged, the clutch CF1is disengaged, the first dog clutch D1is disengaged, and the second dog clutch D2is disengaged. In the second drive state, the third planetary gear device64is in a speed reduction state in which the ring gear R3is mechanically fixed to the fixing member69by the brake BF1. In the second drive state, when the power from the third rotating electric machine MGF is transferred to the front wheel side output shaft62, the rotation of the third rotating electric machine MGF is transferred to the front wheel side output shaft62after speed reduction by the third planetary gear device64.

FIG.11is a skeleton diagram showing a case where the transfer12according to the first embodiment is in the third drive state. The third drive state is a drive state in a mode in which the power transferred to the transfer12in the H4_torque split mode is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in the four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. In the third drive state, the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is changed with the MGF torque from the third rotating electric machine MGF. In other words, the sun gear S3of the third planetary gear device64receives the torque transferred from the rear wheel side output shaft63to the ring gear R3of the third planetary gear device64with the MGF torque from the third rotating electric machine MGF as a reaction force such that the torque transferred to the ring gear R3is distributed to the front wheel3side and the rear wheel4side at an arbitrary ratio. In the third drive state, the transfer12is set to the high-speed side shift stage Hi.

When the transfer12is in the third drive state, as shown inFIG.9, the brake BF1is disengaged, the clutch CF1is disengaged, the first dog clutch D1is in the first input state, and the second dog clutch D2is in the first transfer state. Note that, (1) in the first dog clutch D1inFIG.11indicates that the first dog clutch D1is in the first input state. Further, (1) in the second dog clutch D2inFIG.11indicates that the second dog clutch D2is in the first transfer state.

FIG.12is a skeleton diagram showing a case where the transfer12according to the first embodiment is in the fourth drive state. The fourth drive state is a drive state in a mode in which the power transferred to the transfer12in the H4_LSD mode is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in the four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. The fourth drive state is a drive state in which the rotational differential between the front wheel side output shaft62and the rear wheel side output shaft63is restricted by the engagement control of the clutch CF1. In the fourth drive state, the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is changed by the engagement control of the clutch CF1. In the fourth drive state, the transfer12is set to the high-speed side shift stage Hi.

When the transfer12is in the fourth drive state, as shown inFIG.9, the brake BF1is disengaged, the clutch CF1is under engagement control (half engaged), the first dog clutch D1is in the first input state, and the second dog clutch D2is in the first transfer state. Note that, (1) in the first dog clutch D1inFIG.12indicates that the first dog clutch D1is in the first input state. Further, (1) in the second dog clutch D2inFIG.12indicates that the second dog clutch D2is in the first transfer state.

FIG.13is a skeleton diagram showing a case where the transfer12according to the first embodiment is in the fifth drive state. The fifth drive state is a drive state in a mode in which the power transferred to the transfer12in the H4_Lock mode (fixed distribution 4WD) is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in a four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. The fifth drive state is a drive state in which the rotational differential between the front wheel side output shaft62and the rear wheel side output shaft63is disabled, and the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is fixed. Note that, in the fifth drive state, the transfer12is set to the high-speed side shift stage Hi.

When the transfer12is in the fifth drive state, as shown inFIG.9, the brake BF1is disengaged, the clutch CF1is disengaged, the first dog clutch D1is in the first input state, and the second dog clutch D2is in the second transfer state. Note that, (1) in the first dog clutch D1inFIG.13indicates that the first dog clutch D1is in the first input state. Further, (2) in the second dog clutch D2inFIG.13indicates that the second dog clutch D2is in the second transfer state.

FIG.14is a skeleton diagram showing a case where the transfer12according to the first embodiment is in the sixth drive state. The sixth drive state is a drive state in a mode in which the power transferred to the transfer12in the L4_Lock mode (fixed distribution 4WD) is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in the four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. The sixth drive state is a drive state in which the rotational differential between the front wheel side output shaft62and the rear wheel side output shaft63is disabled, and the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is fixed. In the sixth drive state, the transfer12is set to the low-speed side shift stage Lo.

When the transfer12is in the sixth drive state, as shown inFIG.9, the brake BF1is engaged, the clutch CF1is disengaged, the first dog clutch D1is in the second input state, and the second dog clutch D2is in the second transfer state. Note that, (2) in the first dog clutch D1inFIG.14indicates that the first dog clutch D1is in the second input state. Further, (2) in the second dog clutch D2inFIG.14indicates that the second dog clutch D2is in the second transfer state.

In the transfer12according to the first embodiment, the drive states can be switched between the first drive state and the second drive state, and the third drive state and the fourth drive state in accordance with the traveling state of the vehicle1. Further, in the fifth drive state, the drive states can be switched between the fifth state and the third drive state and the fourth drive state as the driver turns on and off the Lock selection switch92provided on the vehicle1. Further, in the sixth drive state, the drive states can be switched between the fifth drive state and the sixth drive state as the driver turns on and off the Low selection switch90provided on the vehicle1when the vehicle is stopped.

In order to switch the drive state of the transfer12, the electronic control device100controls the hydraulic control circuit111by the transfer control device104based on output signals from various sensors mounted on the vehicle1, the 4WD selection switch86, the Low selection switch90, and the like, and controls the operating states of the actuator that operates the first dog clutch D1and the second dog clutch D2, the brake BF1, and the clutch CF1.

FIG.15is a diagram showing a schematic configuration of the brake BF1. The brake BF1is a hydraulic friction engaging device, and includes a plurality of friction plates304, a first piston301and a second piston302that press the friction plates304, and a first piston hydraulic chamber311and a second piston hydraulic chamber312for applying a hydraulic pressure Pbf1to each of the first piston301and the second piston302.

In the brake BF1, the second piston302and a partition wall member303are provided in the space surrounded by a case member305and the first piston301. The first piston301and the second piston302are in contact with each other and are movable. The partition wall member303is provided between the first piston301and the second piston302such that the hydraulic pressure Pbf1acts on the back surface of the first piston301and does not act on the front surface of the second piston302. The first piston hydraulic chamber311is provided on the back side of the first piston301, and the second piston hydraulic chamber312is provided on the back side of the second piston302. Further, the brake BF1is provided with a return spring306as an urging member that urges the first piston301to the left inFIG.15. Then, the urging force of the return spring306causes the first piston301and the second piston302to move to the left inFIG.15such that the friction plates304are separated and the brake BF1is disengaged.

The hydraulic pressure Pbf1is supplied from the hydraulic control circuit111to the first piston hydraulic chamber311and the second piston hydraulic chamber312of the brake BF1. The hydraulic control circuit111is provided with a switching valve227and an electromagnetic valve SF1as described later. When a valve body228of the switching valve227is set to a first position by the electromagnetic valve SF1, the hydraulic pressure Pbf1is supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312. When the hydraulic pressure Pbf1is supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312, the first piston301and the second piston302abut against each other and move to the right inFIG.15to press the friction plates304so as to engage the brake BF1. At this time, as the pressing force of the friction plates304, a high pressing force can be obtained with the back surface of the first piston301and the back surface of the second piston302as the pressure receiving surfaces for the hydraulic pressure Pbf1, and the engaging force (torque capacity) of the brake BF1with respect to the hydraulic pressure Pbf1is increased. Further, when the valve body228of the switching valve227is set to a second position by the electromagnetic valve SF1, the hydraulic pressure Pbf1is supplied only to the first piston hydraulic chamber311. When the hydraulic pressure Pbf1is supplied to the first piston hydraulic chamber311, the first piston301moves to the right inFIG.15and presses the friction plates304so as to engage the brake BF1. At this time, as the pressing force of the friction plates304, a high pressing force can be obtained with the back surface of the first piston301only as the pressure receiving surface for the hydraulic pressure Pbf1, and the engaging force (torque capacity) of the brake BF1with respect to the hydraulic pressure Pbf1is reduced.

FIG.16is a diagram showing the hydraulic control circuit111in a state where the electromagnetic valve SF1is on.FIG.17is a diagram showing the hydraulic control circuit111in a state where the electromagnetic valve SF1is off.

InFIG.16, a mechanical oil pump200and an electric oil pump201are provided in parallel due to the structure of an oil passage through which the hydraulic oil flows. The mechanical oil pump200and the electric oil pump201each discharge the hydraulic oil that serves as the base of the hydraulic pressure for switching the operating state of each engaging device and supplying lubricant oil to each portion of the compound transmission11and the transfer12. The mechanical oil pump200and the electric oil pump201each suck the hydraulic oil that has returned to an oil pan202through strainers203,204that are suction ports, and discharge the hydraulic oil to discharge oil passages205,206of the mechanical oil pump200and the electric oil pump201, respectively. The discharge oil passages205,206are each connected to an oil passage provided in the hydraulic control circuit111, for example, a line pressure oil passage208that is an oil passage through which a line pressure PL flows. The discharge oil passage205to which the hydraulic oil is discharged from the mechanical oil pump200is connected to the line pressure oil passage208via a check valve210for the mechanical oil pump provided in the hydraulic control circuit111. The discharge oil passage206to which the hydraulic oil is discharged from the electric oil pump201is connected to the line pressure oil passage208via a check valve212for the electric oil pump provided in the hydraulic control circuit111. The mechanical oil pump200rotates together with the engine2to generate an operating hydraulic pressure. The electric oil pump201can generate the operating hydraulic pressure regardless of the rotational state of the engine2.

The hydraulic control circuit111includes a regulator valve214, a switching valve216, and supply oil passages218,222,224,226, discharge oil passage220, the switching valve227, solenoid valves SLT, S1, S2, SL1, SL2, SL3, SL4, SLF1, SLF2, the electromagnetic valve SF1and the like in addition to the line pressure oil passage208, the check valve210for the mechanical oil pump, and the check valve212for the electric oil pump.

The regulator valve214regulates the line pressure PL based on the hydraulic oil discharged from at least one of the mechanical oil pump200and the electric oil pump201. The solenoid valve SLT is, for example, a linear solenoid valve, and is controlled by the electronic control device100so as to output, to the regulator valve214, a pilot pressure Pslt corresponding to the input torque to the stepped transmission unit22and the like. With this configuration, the line pressure PL is set to the hydraulic pressure corresponding to the input torque of the stepped transmission unit22and the like. The source pressure input to the solenoid valve SLT is, for example, a modulator pressure PM adjusted to a constant value by a modulator valve (not shown) with the line pressure PL as the source pressure.

The oil passage of the switching valve216is switched based on the hydraulic pressure output from the solenoid valves S1, S2. The solenoid valves S1, S2each are, for example, an on-off solenoid valve, and controlled by the electronic control device100so as to output the hydraulic pressure to the switching valve216. When the switching valve216is placed in a state where the hydraulic pressure is output from the solenoid valve S2and is not output from the solenoid valve S1, the oil passage is switched so as to connect the line pressure oil passage208and the supply oil passage218. When the switching valve216is placed in a state where the hydraulic pressure is output from both the solenoid valves S1, S2, a state where the hydraulic pressure is not output from either of the solenoid valves S1, S2, or a state where the hydraulic pressure is output from the solenoid valve Si and is not output from the solenoid valve S2, the oil passage between the line pressure oil passage208and the supply oil passage218is blocked and the oil passage is switched such that the supply oil passage218is connected to the discharge oil passage220. The supply oil passage218is an oil passage through which the source pressure input to the solenoid valves SL2, SL3flows. The discharge oil passage220is an open-air oil passage that discharges the hydraulic oil in the hydraulic control circuit111to the outside of the hydraulic control circuit111, that is, returns the hydraulic oil to the oil pan202. For example, when the operation position of the shift lever89is the D operation position for selecting the forward traveling position of the compound transmission11that enables the vehicle1to travel forward, the electronic control device100outputs, to the hydraulic control circuit111, a hydraulic pressure control command signal for causing the solenoid valve S2to output the hydraulic pressure and causing the solenoid valve S1not to output the hydraulic pressure. For example, when the operation position of the shift lever89is the R operation position for selecting the reverse traveling position of the compound transmission11that enables the vehicle1to travel rearward, the electronic control device100outputs, to the hydraulic control circuit111, a hydraulic pressure control command signal for causing the solenoid valves S1, S2to output the hydraulic pressure.

The solenoid valves SL1, SL2, SL3, SL4are, for example, linear solenoid valves, and controlled by the electronic control device100so as to output the hydraulic pressures Pc1, Pc2, Pb1, Pb2to the hydraulic actuators of the engaging devices, respectively. The solenoid valve SL1regulates the hydraulic pressure Pc1supplied to the hydraulic actuator of the clutch C1using the line pressure PL as the source pressure. The solenoid valve SL2regulates the hydraulic pressure Pc2supplied to the hydraulic actuator of the clutch C2using the line pressure PL via the switching valve216as the source pressure. The solenoid valve SL3regulates the hydraulic pressure Pb1supplied to the hydraulic actuator of the brake B1using the line pressure PL via the switching valve216as the source pressure. The solenoid valve SL4regulates the hydraulic pressure Pb2supplied to the hydraulic actuator of the brake B2using the line pressure PL as the source pressure.

The solenoid valve SLF1is, for example, a linear solenoid valve, and is controlled by the electronic control device100so as to output the hydraulic pressure Pcf1to the hydraulic actuator of the clutch CF1. The solenoid valve SLF1regulates the hydraulic pressure Pcf1supplied to the hydraulic actuator of the clutch CF1using the line pressure PL as the source pressure.

The solenoid valve SLF2is, for example, a linear solenoid valve, and is controlled by the electronic control device100so as to output the hydraulic pressure Pbf1to the first piston hydraulic chamber311(BF1first chamber inFIG.16) and the second piston hydraulic chamber312(BF1second chamber inFIG.16) of the brake BF1via the switching valve227. The solenoid valve SLF2regulates the hydraulic pressure Pbf1supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312of the brake BF1using the line pressure PL as the source pressure.

The switching valve227includes the valve body228of which position can be switched between a first position at which the hydraulic pressure Pbf1output from the solenoid valve SL2to the first piston hydraulic chamber311and the second piston hydraulic chamber312of the brake BF1and a second position at which the hydraulic pressure Pbf1is supplied only to the first piston hydraulic chamber311. The switching valve227switches the position of the valve body228between the first position and the second position based on the hydraulic pressure output from the electromagnetic valve SF1. The electromagnetic valve SF1is controlled by the electronic control device100so as not to generate the hydraulic pressure when the current supplied to the electromagnetic valve SF1is off and does not flow, and to generate the hydraulic pressure when the current supplied to the electromagnetic valve SF1is turned on and flows.

The hydraulic control circuit111shown inFIG.16is in a state where the current supplied to the electromagnetic valve SF1is turned on and the hydraulic pressure is generated. In this state, the valve body228of the switching valve227is pushed up against the urging force of a spring230by the hydraulic pressure from the electromagnetic valve SF1to reach the second position. With this configuration, the hydraulic pressure Pbf1from the solenoid valve SLF2is supplied only to the first piston hydraulic chamber311of the brake BF1.

On the other hand, the hydraulic control circuit111shown inFIG.17is in a state where the current supplied to the electromagnetic valve SF1is off and the hydraulic pressure is not generated. In this state, the hydraulic pressure from the electromagnetic valve SF1is not applied to the switching valve227. Therefore, the valve body228of the switching valve227is pushed down by the urging force of the spring230to reach the first position. With this configuration, the hydraulic pressure Pbf1from the solenoid valve SLF2is supplied to the first piston hydraulic chamber311(BF1first chamber inFIG.17) and the second piston hydraulic chamber312(BF1second chamber inFIG.17) of the brake BF1.

In the transfer12according to the first embodiment, the L4_Lock mode can be set as the first traveling mode in which the power from the engine2is input to the sun gear S3of the third planetary gear device64, and the ring gear R3of the third planetary gear device64is fixed to the fixing member69by the brake BF1such that the power input to the sun gear S3is decelerated and output from the carrier CA3of the third planetary gear device64to the front wheel side output shaft62and the rear wheel side output shaft63to cause the vehicle1to travel in the four-wheel drive state.

Further, in the transfer12according to the first embodiment, the EV(FF)_Lo mode can be set as the second traveling mode in which the power from the third rotating electric machine MGF is input to the sun gear S3of the third planetary gear device64, and the third planetary gear device64is fixed to the fixing member69by the brake BF1such that the power input to the sun gear S3is decelerated and output from the carrier CA3of the third planetary gear device64to the front wheel side output shaft62to cause the vehicle1to travel in the two-wheel drive state.

Then, in the first embodiment, when the L4_Lock mode is set, the electronic control device100controls the hydraulic control circuit111such that the hydraulic pressure Pbf1is supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312. When the EV(FF)_Lo mode is set, the electronic control device100controls the hydraulic control circuit111such that the hydraulic pressure Pbf1is supplied only to the first piston hydraulic chamber311. The power input from the engine2to the sun gear S3in the L4_Lock mode is larger than the power input to the sun gear S3from the third rotating electric machine MGF in the EV(FF)_Lo mode. With this configuration, when the EV(FF)_Lo mode is set while the torque capacity of the brake BF1is matched with the torque capacity required in the L4_Lock mode, the torque capacity of the brake BF1with respect to the hydraulic pressure Pbf1is reduced, whereby the shock when the EV(FF)_Lo mode is set can be suppressed.

Further, in the first embodiment, the hydraulic control circuit111includes the switching valve227provided with the valve body228of which position can be switched between the first position at which the hydraulic pressure Pbf1is supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312and the second position at which the hydraulic pressure Pbf1is supplied only to the first piston hydraulic chamber311, and the electromagnetic valve SF1that switches the position of the valve body228between the first position and the second position. When the electromagnetic valve SF1is turned off, the position of the valve body228is set to the first position. With this configuration, when a failure that the electromagnetic valve SF1is off occurs, the hydraulic pressure Pbf1can be supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312. Therefore, the torque capacity of the brake BF1can be matched with the torque capacity required in the L4_Lock mode.

Further, in the first embodiment, the electronic control device100may prohibit setting of the EV(FF)_Lo mode when the failure that the electromagnetic valve SF1is off occurs. With this configuration, it is possible to suppress the shock caused by setting the EV(FF)_Lo mode when the failure that the electromagnetic valve SF1is off occurs.

Further, in the first embodiment, the electronic control device100may reduce the hydraulic pressure Pbf1to be supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312for setting the EV(FF)_Lo mode when the failure that the electromagnetic valve SF1is off occurs. With this configuration, it is possible to suppress a shock caused by setting the EV(FF)_Lo mode when the failure that the electromagnetic valve SF1is off occurs.

FIG.18is a flowchart showing an example of control executed by the electronic control device100according to the first embodiment.

First, the electronic control device100determines in step ST1whether the failure that the electromagnetic valve SF1is off occurs. When the electronic control device100determines that the failure that the electromagnetic valve SF1is off does not occur (No in step ST1), the electronic control device100determines whether switching to the L4_Lock mode has occurred in step ST2. When the electronic control device100determines that switching to the L4_Lock mode has not occurred (No in step ST2), the electronic control device100determines whether switching to the EV(FF)_Lo mode has occurred in step ST3.

When the electronic control device100determines that switching to the EV(FF)_Lo mode has not occurred (No in step ST3), the electronic control device100returns a series of controls. On the other hand, when the electronic control device100determines that switching to the EV(FF)_Lo mode has occurred (Yes in step ST3), the current of the electromagnetic valve SF1is turned on in step ST4to generate the hydraulic pressure. With this configuration, the valve body228of the switching valve227is positioned at the second position as shown inFIG.16, and when the mode is switched to the EV(FF)_Lo mode, the hydraulic pressure Pbf1from the solenoid valve SLF2is supplied to the first piston hydraulic chamber311of the brake BF1. After that, the electronic control device100returns a series of controls.

Further, when the electronic control device100determines in step ST1that the failure that the electromagnetic valve SF1is off occurs (Yes in step ST1), the electronic control device100prohibits setting of the EV(FF)_Lo mode or permits switching to the EV(FF)_Lo mode to reduce the hydraulic pressure Pbf1in the process of switching in step ST5. With this configuration, when setting of the EV(FF)_Lo mode is prohibited, the shock caused by setting the EV(FF)_Lo mode at the time when the failure that the electromagnetic valve SF1is off occurs can be suppressed. Further, when switching to the EV(FF)_Lo mode is permitted and the hydraulic pressure Pbf1in the process of switching is reduced, the shock caused by setting the EV(FF)_Lo mode at the time when the failure that the electromagnetic valve SF1is off occurs can be suppressed. Further, when the EV(FF)_Lo mode is already in use, the EV(FF)_Lo mode is immediately switched to the EV(FF)_Hi mode. After that, the electronic control device100returns a series of controls.

Further, when the electronic control device100determines in step ST2that switching to the L4_Lock mode has occurred (Yes in step ST2), the current of the electromagnetic valve SF1is turned off in step ST6and the hydraulic pressure is not generated. With this configuration, the valve body228of the switching valve227is positioned at the first position as shown inFIG.17, and when the mode is switched to the H4_Lock mode, the hydraulic pressure Pbf1from the solenoid valve SLF2is supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312of the brake BF1. After that, the electronic control device100returns a series of controls.

In the drive device10according to the first embodiment, as a modification, the switching valve227provided in the hydraulic control circuit111may be configured such that the valve body228is positioned at the first position as shown inFIG.19when the electromagnetic valve SF1is turned on, and the valve body228is positioned at the second position as shown inFIG.20when the electromagnetic valve SF1is turned off. With this configuration, when the failure that the electromagnetic valve SF1is off occurs, the hydraulic pressure Pbf1is supplied only to the first piston hydraulic chamber311. Therefore, the torque capacity of the brake BF1can be matched with the torque capacity required in the EV(FF)_Lo mode.

Further, in the modification, the electronic control device100may prohibit setting of the L4_Lock mode when the failure that the electromagnetic valve SF1is off occurs. With this configuration, it is possible to suppress deterioration of durability of the friction plates304caused by setting the L4_Lock mode when the failure that the electromagnetic valve SF1is off occurs.

Further, in the modification, the electronic control device100may reduce the torque (engine torque) output from the engine2during traveling of the vehicle1in the L4_Lock mode when the failure that the electromagnetic valve SF1is off occurs. With this configuration, it is possible to suppress deterioration of durability of the friction plates304caused by setting the L4_Lock mode when the failure that the electromagnetic valve SF1is off occurs.

Second Embodiment

Next, the vehicle1provided with the drive device10according to a second embodiment will be described. In the description of the second embodiment, reference signs are assigned for the same configuration as that of the first embodiment, and the description thereof will be omitted as appropriate.

FIG.21is a skeleton diagram schematically showing the transfer12according to the second embodiment, and is a skeleton diagram showing a case where the transfer12is in the first drive state. In the transfer12according to the second embodiment, the carrier CA3of the third planetary gear device64is constantly connected to the rear wheel side output shaft63so as to rotate integrally with the rear wheel side output shaft63.

The transfer12includes the connection switching device40(first dog clutch D1and second dog clutch D2), the brake BF1, and the clutch CF1.

The transfer12according to the second embodiment includes the transfer member65that functions as an input rotating member of power to the front wheel3side as a rotating member that constitutes a power transfer path on the front wheel3side. The transfer member65is connected to the drive gear66so as to rotate integrally. The transfer member65is a rotating member that transfers power to the front wheel side output shaft62. The transfer member65and the drive gear66are disposed so as to be rotatable relative to the rear wheel side output shaft63. In the transfer12according to the second embodiment, the transfer member65, the drive gear66, and the third planetary gear device64are disposed on the same rotation center as the rear wheel side output shaft63.

The second dog clutch D2is a second disconnection-connection mechanism for switching the connection destination of the transfer member65. The second dog clutch D2can selectively connect the transfer member65to the rear wheel side output shaft63or the second rotating member52(ring gear R3).

The second dog clutch D2includes a second switching sleeve42as a switching member. The second switching sleeve42includes the first gear teeth42athat can mesh with the gear teeth52aof the second rotating member52that rotates integrally with the ring gear R3or the second gear teeth63bof the rear wheel side output shaft63. Further, the second switching sleeve42includes the second gear teeth42bthat constantly mesh with the gear teeth65aof the transfer member65. The second switching sleeve42is moved in the axial direction by the actuator of the second dog clutch D2. The second switching sleeve42is switched to any of a first transfer state in which the first gear teeth42amesh with the gear teeth52aof the second rotating member52while the second gear teeth42bconstantly mesh with the gear teeth65aof the transfer member65, a disengaged state in which the first gear teeth42ado not mesh with any of the gear teeth52aof the second rotating member52and the second gear teeth63bof the rear wheel side output shaft63, and a second transfer state in which the first gear teeth42amesh with the second gear teeth63bof the rear wheel side output shaft63.

The brake BF1selectively fixes the ring gear R3of the third planetary gear device64to a fixing member69. The transfer12is set to the high-speed side shift stage Hi when the brake BF1is disengaged, and is set to the low-speed side shift stage Lo when the brake BF1is engaged. The clutch CF1selectively connects the sun gear S3and the carrier CA3of the third planetary gear device64.

FIG.22is a diagram showing the engagement relationship of each rotating member in the transfer12according to the second embodiment. The transfer12according to the second embodiment includes the rear wheel side output shaft63, the front wheel side output shaft62, and the third planetary gear device64. The rear wheel side output shaft63is the first output shaft that is connected to the engine2(and the first rotating electric machine MG1and the second rotating electric machine MG2) as the first power source and outputs power to the rear wheels4that are one of the front wheels3and the rear wheels4. The front wheel side output shaft62is the second output shaft that outputs the power to the front wheels3that are the other of the front wheels3and the rear wheels4. The third planetary gear device64is the differential mechanism including the sun gear S3that is the first rotating element, the carrier CA3that is the second rotating element, and the ring gear R3that is the third rotating element. Further, the transfer12according to the second embodiment includes the brake BF1that selectively fixes the ring gear R3to the fixing member69. Further, the transfer12according to the second embodiment is configured to input at least the power from the engine2that is the first power source to the sun gear S3, and fix the ring gear R3to the fixing member69to decelerate the power input to the sun gear S3and output the power from the carrier CA3to the rear wheel side output shaft63and the front wheel side output shaft62such that the vehicle can travel in the four-wheel drive state. Further, the transfer12according to the second embodiment is configured to input the power from the third rotating electric machine MGF that is the second power source to the sun gear S3, and fix the ring gear R3to the fixing member69to decelerate the power input to the sun gear S3and output the power from the carrier CA3to the rear wheel side output shaft63that is one of the first output shaft and the second output shaft such that the vehicle can travel in the two-wheel drive state.

FIG.23is a diagram showing the relationship between each of the drive states of the transfer12according to the second embodiment and an operating state of each engaging device. InFIG.23, a white circle indicates engagement, a white triangle indicates engagement as needed, and blank indicates disengagement.

The first drive state shown inFIG.21is a drive state in the EV traveling mode in which the vehicle1travels using the power from the third rotating electric machine MGF in the EV(FR)_Hi mode, and also in the two-wheel drive state in which the power from the third rotating electric machine MGF is transferred only to the rear wheels4. In the first drive state, the transfer12is set to a high-speed side shift stage Hi.

When the transfer12is in the first drive state, as shown inFIG.23, the brake BF1is disengaged, the clutch CF1is engaged, the first dog clutch D1is disengaged, and the second dog clutch D2is disengaged. In the first drive state, the third planetary gear device64is in a direct connection state in which the sun gear S3and the carrier CA3are connected by the clutch CF1. In the first drive state, when the power from the third rotating electric machine MGF is transferred to the rear wheel side output shaft63, the rotation of the third rotating electric machine MGF is transferred to the rear wheel side output shaft63without speed change by the third planetary gear device64.

FIG.24is a skeleton diagram showing a case where the transfer12according to the second embodiment is in the second drive state. The second drive state is a drive state in the EV traveling mode in which the vehicle1travels using the power from the third rotating electric machine MGF in the EV(FR)_Lo mode, and also in the two-wheel drive state in which the power from the third rotating electric machine MGF is transferred only to the rear wheels4. In the second drive state, the transfer12is set to a low-speed side shift stage Lo.

When the transfer12is in the second drive state, as shown inFIG.23, the brake BF1is engaged, the clutch CF1is disengaged, the first dog clutch D1is disengaged, and the second dog clutch D2is disengaged. In the second drive state, the third planetary gear device64is in a speed reduction state in which the ring gear R3is mechanically fixed to the fixing member69by the brake BF1. In the second drive state, the third rotating electric machine MGF is connected to the rear wheel side output shaft63on the power transfer path via the third planetary gear device64in the shifting state. Therefore, in the second drive state, the third rotating electric machine MGF is connected to the rear wheel side output shaft63on the power transfer path via the third planetary gear device64in the shifting state. Therefore, in the second drive state, when the power from the third rotating electric machine MGF is transferred to the rear wheel side output shaft63, the rotation of the third rotating electric machine MGF is transferred to the rear wheel side output shaft63after speed reduction by the third planetary gear device64.

FIG.25is a skeleton diagram showing a case where the transfer12according to the second embodiment is in the third drive state. The third drive state is a drive state in a mode in which the power transferred to the transfer12in the H4torque split mode is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in the four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. In the third drive state, the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is changed with the MGF torque from the third rotating electric machine MGF. In other words, the sun gear S3of the third planetary gear device64receives the torque transferred from the rear wheel side output shaft63to the ring gear R3of the third planetary gear device64with the MGF torque from the third rotating electric machine MGF as a reaction force such that the torque transferred to the ring gear R3is distributed to the front wheel3side and the rear wheel4side at an arbitrary ratio. In the third drive state, the transfer12is set to the high-speed side shift stage Hi.

When the transfer12is in the third drive state, as shown inFIG.23, the brake BF1is disengaged, the clutch CF1is disengaged, the first dog clutch D1is in the first input state, and the second dog clutch D2is in the first transfer state. Note that, (1) in the first dog clutch D1inFIG.25indicates that the first dog clutch D1is in the first input state. Further, (1) in the second dog clutch D2inFIG.25indicates that the second dog clutch D2is in the first transfer state.

FIG.26is a skeleton diagram showing a case where the transfer12according to the second embodiment is in the fourth drive state. The fourth drive state is a drive state in a mode in which the power transferred to the transfer12in the H4_LSD mode is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in the four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. The fourth drive state is a drive state in which the rotational differential between the front wheel side output shaft62and the rear wheel side output shaft63is restricted by the engagement control of the clutch CF1. In the fourth drive state, the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is changed by the engagement control of the clutch CF1. In the fourth drive state, the transfer12is set to the high-speed side shift stage Hi.

When the transfer12is in the fourth drive state, as shown inFIG.23, the brake BF1is disengaged, the clutch CF1is under engagement control (half engaged), the first dog clutch D1is in the first input state, and the second dog clutch D2is in the first transfer state. Note that, (1) in the first dog clutch D1inFIG.26indicates that the first dog clutch D1is in the first input state. Further, (1) in the second dog clutch D2inFIG.26indicates that the second dog clutch D2is in the first transfer state.

FIG.27is a skeleton diagram showing a case where the transfer12according to the second embodiment is in the fifth drive state. The fifth drive state is a drive state in a mode in which the power transferred to the transfer12in the H4_Lock mode (fixed distribution 4WD) is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in a four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. The fifth drive state is a drive state in which the rotational differential between the front wheel side output shaft62and the rear wheel side output shaft63is disabled, and the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is fixed. Note that, in the fifth drive state, the transfer12is set to the high-speed side shift stage Hi.

When the transfer12is in the fifth drive state, as shown inFIG.23, the brake BF1is disengaged, the clutch CF1is disengaged, the first dog clutch D1is in the first input state (1), and the second dog clutch D2is in the second transfer state. Note that, (1) in the first dog clutch D1inFIG.27indicates that the first dog clutch D1is in the first input state. Further, (2) in the second dog clutch D2inFIG.27indicates that the second dog clutch D2is in the second transfer state.

FIG.28is a skeleton diagram showing a case where the transfer12according to the second embodiment is in the sixth drive state. The sixth drive state is a drive state in a mode in which the power transferred to the transfer12in the L4Lock mode (fixed distribution 4WD) is distributed to the front wheel3side and the rear wheel4side to cause the vehicle1to travel, and is also in the four-wheel drive state in which the power is transferred to the front wheels3and the rear wheels4. The sixth drive state is a drive state in which the rotational differential between the front wheel side output shaft62and the rear wheel side output shaft63is disabled, and the torque distribution ratio at which the torque from the input shaft61is distributed to the front wheel side output shaft62and the rear wheel side output shaft63is fixed. In the sixth drive state, the transfer12is set to the low-speed side shift stage Lo.

When the transfer12is in the sixth drive state, as shown inFIG.23, the brake BF1is engaged, the clutch CF1is disengaged, the first dog clutch D1is in the second input state, and the second dog clutch D2is in the second transfer state. Note that, (2) in the first dog clutch D1inFIG.28indicates that the first dog clutch D1is in the second input state. Further, (2) in the second dog clutch D2inFIG.28indicates that the second dog clutch D2is in the second transfer state.

In the transfer12according to the second embodiment, the L4_Lock mode can be set as the first traveling mode in which the power from the engine2is input to the sun gear S3of the third planetary gear device64, and the ring gear R3of the third planetary gear device64is fixed to the fixing member69by the brake BF1such that the power input to the sun gear S3is decelerated and output from the carrier CA3of the third planetary gear device64to the front wheel side output shaft62and the rear wheel side output shaft63to cause the vehicle1to travel in the four-wheel drive state.

Further, in the transfer12according to the second embodiment, the EV(FR)_Lo mode can be set as the second traveling mode in which the power from the third rotating electric machine MGF is input to the sun gear S3of the third planetary gear device64, and the third planetary gear device64is fixed to the fixing member69by the brake BF1such that the power input to the sun gear S3is decelerated and output from the carrier CA3of the third planetary gear device64to the rear wheel side output shaft63to cause the vehicle1to travel in the two-wheel drive state.

Further, the drive device10according to the second embodiment has the configurations of the brake BF1and the hydraulic control circuit111similar to the configurations described in the first embodiment with reference to theFIGS.15,16,17,19,20, and the like.

Then, in the drive device10according to the second embodiment, various controls to be executed by the electronic control device100described in the first embodiment usingFIG.18and the like can be implemented. At this time, the EV(FF)_Lo mode in the first embodiment may be replaced with the EV(FR)_Lo mode. For example, the drive device10according to the second embodiment controls the hydraulic control circuit111such that the hydraulic pressure Pbf1is supplied to the first piston hydraulic chamber311and the second piston hydraulic chamber312when the L4_Lock mode is set, and controls the hydraulic control circuit111such that the hydraulic pressure Pbf1is supplied only to the first piston hydraulic chamber311when the EV(FR)_Lo mode is set, similar to the configuration in the first embodiment described with reference toFIG.18and the like. With this configuration, it is possible to suppress the shock when the EV(FR)_Lo mode is set.