JP2013108604A - Vehicle driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle driving device that prevents a torque loss at a speed change, and improves drivability.SOLUTION: The device includes: a first motor generator 2 that outputs rotative power; a transmission 4 that changes a speed of the rotative power outputted from the first motor generator 2 to output it and enables the switching of a gear ratio; a differential gear 5 that differentially drives two wheels 6a and 6b with the rotative power outputted from the transmission 4; and a second motor generator 3 that outputs the rotative power toward the differential gear 5 via the transmission 4. The transmission 4 is configured to transmit the rotative power outputted from the second motor generator 3 to the differential gear 5 when the gear ratio of the rotative power outputted from the first motor generator 2 is switched.

Description

  The present invention relates to a vehicle drive device that drives drive wheels via a transmission by a driving force of an electric motor.

  Some vehicles using an electric motor as a power source include a vehicle drive device having a transmission (speed reducer) capable of switching a gear position in a power transmission path between the electric motor and drive wheels.

  For example, in the devices described in Patent Documents 1 and 2, the electric motor is used as a power source, the transmission is configured to be switchable in two stages, the first shaft is provided coaxially with the output shaft of the electric motor, and the first shaft The first shaft is formed by an outer rotating shaft and an inner rotating shaft, and a first reduction gear train is provided between the inner rotating shaft and the second shaft. A second reduction gear train is provided between the two shafts, the first friction clutch that fastens the output shaft and the inner rotation shaft by the operation of the first shift switching actuator, and the output shaft and the outer rotation by the operation of the second shift switching actuator. A second friction clutch for fastening the shaft is provided to change the gear position.

  Further, in the devices described in Patent Documents 3 and 4, the electric motor is used as a power source, the transmission is configured to be switchable in two stages, and the first shaft and the second shaft that are rotationally driven by the electric motor are interposed. A first reduction gear train and a second reduction gear train are provided, and between the first output gear and the second shaft of the first reduction gear train and between the second output gear and the second shaft of the second reduction gear train. Two-way roller clutches are incorporated in each, and the gear stage is switched by controlling engagement and disengagement of the two-way roller clutch by a gear ratio switching mechanism.

  Furthermore, in the device described in Patent Document 5, the motor (40) is used as a power source, the reduction gear is configured to be switchable in two stages, and switching (96) for connecting the output shaft of the electric motor (40) and the hollow shaft (100). And a second gear set (86) that decelerates and outputs the rotational power of the output shaft of the electric motor (40) via the first gear set (82) and a switch (94) that connects the hollow shaft (100). The gear stage is switched by controlling the clutch switching section (78).

JP 2011-89632 A JP 2011-33071 A JP 2011-58534 A JP 2011-57030 A US Patent Application Publication No. 2009/0211824

  The following analysis is given by the inventor.

  However, in the devices described in Patent Documents 1 and 2, since the power source is only one electric motor, it is necessary to connect and disconnect the power when switching between the first friction clutch and the second friction clutch at the time of shifting. Torque loss occurs when the vehicle is disconnected (the vehicle is idle), and drivability is poor.

  Further, in the devices described in Patent Documents 3 and 4, since the power source is only one electric motor, it is necessary to connect / disconnect the power when controlling the rotation of the cage of the 2-way roller clutch at the time of shifting. Torque loss occurs when the vehicle enters the state (the vehicle is idling), and drivability is poor.

  Furthermore, in the apparatus described in Patent Document 5, since there is only one power source, it is necessary to connect / disconnect power at the shift clutch switching unit at the time of shifting, and torque loss occurs when the disconnection occurs (vehicles). And drivability is bad.

  The main subject of this invention is providing the vehicle drive device which can eliminate the torque omission at the time of a gear shift, and can improve drivability.

  In one aspect of the present invention, in a vehicle drive device, a first motor generator that outputs rotational power, and a speed change that allows the rotational power output from the first motor generator to be shifted and output while switching the gear ratio. , A differential device that differentially drives two wheels by the rotational power output from the transmission, and a second motor generator that outputs rotational power to the differential device via the transmission The transmission transmits the rotational power output from the second motor generator to the differential device when the transmission gear ratio of the rotational power output from the first motor generator is switched. It is comprised as follows.

  According to the present invention, torque loss is prevented by the driving force of the second motor generator at the time of shifting, and drivability can be improved, and fuel efficiency (efficiency) is improved by driving assist of the second motor generator at the time of acceleration. Can be made.

It is the block diagram which showed typically the structure of the vehicle drive device which concerns on Example 1 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 1 of this invention. It is the time chart which showed typically the change of the rotation speed of the 1st motor generator and the 2nd motor generator at the time of the speed change of the vehicle drive device concerning Example 1 of the present invention. It is a schematic diagram for demonstrating the process of determining the output torque of the 1st motor generator and the 2nd motor generator at the time of the acceleration assistance of the vehicle drive device which concerns on Example 1 of this invention. It is the table | surface which showed typically the operation state of each driving | running | working pattern of the vehicle drive device which concerns on Example 1 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 2 of this invention. It is the table | surface which showed typically the operation state of each driving | running | working pattern of the vehicle drive device which concerns on Example 2 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 3 of this invention. It is the table | surface which showed typically the operation state of each driving | running | working pattern of the vehicle drive device which concerns on Example 3 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 4 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 5 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 6 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 7 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 8 of this invention. It is the skeleton figure which showed typically the structure of the drive system of the vehicle drive device which concerns on Example 9 of this invention.

  In the vehicle drive device according to the embodiment of the present invention, the first motor generator (2 in FIG. 2) that outputs rotational power and the rotational power output from the first motor generator are shifted and output, and the gear ratio is changed. A changeable transmission (4 in FIG. 2) and a differential device (5 in FIG. 2) that differentially drives two wheels (6a and 6b in FIG. 2) by the rotational power output from the transmission. ) And a second motor generator (3 in FIG. 2) that outputs rotational power to the differential through the transmission, and the transmission is output from the first motor generator. When the speed ratio of the rotational power is switched, the rotational power output from the second motor generator is transmitted to the differential device.

  In the vehicle drive device of the present invention, the transmission changes the rotational power output from the second motor generator when the rotational power output from the first motor generator is shifted and output. It is preferable to be configured to transmit to the moving device.

  In the vehicle drive device of the present invention, the transmission is in a state where the rotational power output from the second motor generator is transmitted and is not transmitted in a power transmission path from the second motor generator to the differential device. It is preferable to provide a switching mechanism capable of switching.

  In the vehicle drive device of the present invention, the transmission is a one-way that allows the rotational power output from the second motor generator only in one direction in the power transmission path from the second motor generator to the differential device. It is preferable to provide a clutch.

  In the vehicle drive device of the present invention, it is preferable that the transmission is configured to always transmit the rotational power output from the second motor generator to the differential device.

  In the vehicle drive device of the present invention, it is preferable that the second motor generator is an induction motor.

  In the vehicle drive device of the present invention, the transmission is arranged in parallel to the first shaft to which the rotational power output from the first motor generator is input, and to the first shaft. A second shaft that outputs rotational power toward the device, another switching mechanism that switches a transmission gear ratio of the rotational power transmitted from the first shaft to the second shaft, and a parallel to the first shaft. And a third shaft that receives the rotational power output from the second motor generator and outputs the rotational power toward the second shaft or the differential.

  In the vehicle drive device of the present invention, it is preferable that the third shaft is arranged coaxially with the first shaft and outputs rotational power toward the second shaft.

  In the vehicle drive device of the present invention, it is preferable that the third shaft is disposed coaxially with the second shaft and outputs rotational power toward the second shaft.

  In the vehicle drive device of the present invention, the output shaft of the first shaft and the first motor generator is a hollow shaft, and the axle for transmitting rotational power from the differential device to the wheel on one side is the It is preferable to be inserted inside the hollow shaft.

  The vehicle drive device according to the present invention includes a fourth shaft that is arranged in parallel to the first shaft and outputs rotational power toward the second shaft, and the third shaft is the fourth shaft. It is preferable that the rotary power is output to the second shaft via the fourth shaft while being coaxially arranged.

  The vehicle drive device according to the present invention includes a fourth shaft that is arranged in parallel to the first shaft and outputs rotational power toward the differential device, and the third shaft is the fourth shaft. It is preferable that the rotational power is output to the differential device via the fourth shaft.

  Note that, in the present application, where reference numerals are attached to the drawings, these are only for the purpose of helping understanding, and are not intended to be limited to the illustrated embodiments.

  A vehicle drive device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically showing the configuration of the vehicle drive device according to the first embodiment of the present invention.

  Referring to FIG. 1, a vehicle drive device 1 is a device that drives a vehicle. The vehicle drive device 1 is mounted on an electric vehicle having two power sources (motor generators 2 and 3). The vehicle drive device 1 is equipped with a second motor generator 3 that operates at the time of changing gears as a sub-power source in order to prevent torque loss that occurs when the gears are changed using the first motor generator 2 as a main power source. doing. The vehicle drive device 1 includes, as main components, a first motor generator 2, a second motor generator 3, a transmission 4, a differential device 5, wheels 6 a and 6 b, a first inverter 7, 2 inverter 8, battery 9, transmission control device 10, first motor generator control device 11, second motor generator control device 12, battery control device 13, main control device 14, sensor 16, Have

  The first motor generator 2 is a synchronous generator motor (which may be an induction type) that drives as a motor and also as a generator. The rotational power of the first motor generator 2 is transmitted to the transmission 4. First motor generator 2 exchanges power with battery 9 via first inverter 7 (including a step-up / down converter). The first motor generator 2 is electrically connected to the first motor generator control device 11 via the first inverter 7, and the operation (drive, power generation, regeneration, etc.) is controlled by the first motor generator control device 11. The The first motor generator 2 can regenerate using the rotational power from the transmission 4 to charge the battery 9, or can output rotational power to the transmission 4 using the electric power from the battery 9. The relationship between the first motor generator 2 and the transmission 4 will be described later.

  The second motor generator 3 is a synchronous generator motor (which may be an induction type) that drives as a motor and also as a generator. As the second motor generator 3, one having an output smaller than that of the first motor generator 2 can be used. The rotational power of the second motor generator 3 is transmitted to the differential device 5 via the transmission 4. Second motor generator 3 exchanges power with battery 9 via second inverter 8 (including a step-up / down converter). The second motor generator 3 is electrically connected to the second motor generator control device 12 via the second inverter 8, and the operation (drive, power generation, regeneration, etc.) is controlled by the second motor generator control device 12. The The second motor generator 3 can regenerate using the rotational power from the transmission 4 to charge the battery 9 or output the rotational power to the transmission 4 using the power from the battery 9. The relationship between the second motor generator 3 and the transmission 4 will be described later.

  The transmission 4 is a mechanism for shifting the rotational power output from any of the motor generators 2 and 3 and transmitting it to the differential device 5. The transmission 4 is configured to be able to switch the gear ratio. In the transmission 4, the rotational power output from any of the motor generators 2 and 3 is input to a gear mechanism (two-shaft gear mechanism), and is shifted by the gear mechanism and output to the differential device 5. The transmission 4 is configured to be able to switch the shift speed, and has a switching mechanism that switches a connection state between predetermined rotating elements in the gear mechanism, and an actuator (24 in FIG. 2) that operates the switching mechanism. , 33). The transmission 4 has a sensor (not shown) that detects the rotational speed of a predetermined rotating element. In the transmission 4, an actuator and a sensor are electrically connected to the transmission control device 10, and the operation of the actuator is controlled by the transmission control device 10. The detailed configuration of the transmission 4 will be described later.

  The differential device 5 is a device that drives the wheels 6 a and 6 b to be differentially driven by the rotational power from the transmission 4. The detailed configuration of the differential device 5 will be described later.

  The wheels 6a are wheels arranged on one of the left and right sides of the vehicle, and the rotational power from the differential device 5 is transmitted to the wheels 6a. The wheel 6b is a wheel arranged on the other of the left and right sides of the vehicle, and the rotational power from the differential device 5 is transmitted.

  The first inverter 7 is a device that controls the operation (drive, power generation, regeneration, etc.) of the first motor generator 2 in response to a control signal from the first motor generator control device 11. The first inverter 7 is electrically connected to the first motor generator control device 11, the first motor generator 2, and the battery 9. The first inverter 7 can boost the voltage from the battery 9 and supply it to the first motor generator 2, and can step down the voltage generated or regenerated by the first motor generator 2 and supply it to the battery 9.

  The second inverter 8 is a device that controls the operation (drive, power generation, regeneration, etc.) of the second motor generator 3 in accordance with a control signal from the second motor generator control device 12. The second inverter 8 is electrically connected to the second motor generator control device 12, the second motor generator 3, and the battery 9. The second inverter 8 can boost the voltage from the battery 9 and supply it to the second motor generator 3, and can step down the voltage generated or regenerated by the second motor generator 3 and supply it to the battery 9.

  The battery 9 is a secondary battery that can be discharged and stored. The battery 9 is electrically connected to the first inverter 7, the second inverter 8, and the battery control device 13. The battery 9 can supply electric power to the first inverter 7 and the second inverter 8, and can store electricity using electric power from the first inverter 7 and the second inverter 8. The battery 9 is monitored for electric power stored by the battery control device 13.

  The transmission control device 10 is a computer (electronic control device) that controls the operation of actuators (24 and 33 in FIG. 2) in the transmission 4. The transmission control device 10 is electrically connected to an actuator (24, 33 in FIG. 2), various sensors (not shown; for example, a rotation sensor), and the main control device 14. The transmission control device 10 performs control processing based on a predetermined program (including a database, a map, and the like) in response to a control signal from the main control device 14.

  The first motor generator control device 11 is a computer (electronic control device) that controls the operation of the first motor generator 2 via the first inverter 7. The first motor generator control device 11 is electrically connected to the first inverter 7, various sensors (not shown; for example, a rotation sensor) and the main control device 14. The first motor generator control device 11 performs control processing based on a predetermined program (including a database, a map, and the like) in response to a control signal from the main control device 14.

  The second motor generator control device 12 is a computer (electronic control device) that controls the operation of the second motor generator 3 via the second inverter 8. The second motor generator control device 12 is electrically connected to the second inverter 8, various sensors (not shown; for example, a rotation sensor) and the main control device 14. The second motor generator control device 12 performs control processing based on a predetermined program (including a database, a map, etc.) in response to a control signal from the main control device 14.

  The battery control device 13 is a computer (electronic control device) that controls the battery 9. The battery control device 13 is electrically connected to the battery 9 and the main control device 14. The battery control device 13 monitors the power stored in the battery 9 and provides information related to the detected power to the main control device 14.

  The main control device 14 includes a first motor generator 2, a second motor generator 3, and a transmission via the transmission control device 10, the first motor generator control device 11, the second motor generator control device 12, and the battery control device 13. 4 and a computer (electronic control device) for controlling the operation of the battery 9. The main control device 14 determines a predetermined program (database, map, etc.) according to an input signal (a predetermined state of the vehicle) from various sensors 16 (vehicle speed, accelerator function, brake signal, wheel rotation speed, shift position, etc.). Control processing is performed based on. The main control device 14 determines a travel pattern (see FIG. 5) based on input signals from the various sensors 16, and the transmission control device 10, the first motor generator control device 11, according to the determined travel pattern, A control signal is output to the second motor generator control device 12 and the battery control device 13.

  The sensor 16 is a device that detects a predetermined state of the vehicle. As the sensor 16, for example, a sensor that detects a predetermined state of the vehicle such as a vehicle speed, an accelerator opening degree, a brake signal, a wheel rotation speed, and a shift position can be used.

  Next, details of the configuration of the transmission in the vehicle drive device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a skeleton diagram schematically showing the configuration of the drive system of the vehicle drive device according to the first embodiment of the present invention.

  The drive system of the vehicle drive device (2 in FIG. 1) has a structure having a parallel triaxial gear unit from the first motor generator 2 to the wheels 6a and 6b, and the first motor generator on the first axis. 2 is input, and the rotational power is output toward the wheels 6a and 6b on the third axis. The drive system of the vehicle drive device (2 in FIG. 1) includes two motor generators 2 and 3, a transmission 4, a differential device 5, and wheels 6a and 6b.

  The first motor generator 2 includes a stator 2c serving as a stator, a rotor 2b disposed inside the stator 2c, and an output shaft 2a that rotates integrally with the rotor 2b. The output shaft 2 a is connected to the first shaft 20 of the transmission 4 and rotates integrally with the first shaft 20. The case portion of the first motor generator 2 is fixed to the housing 34 of the transmission 4. The first motor generator 2 is electrically connected to a first motor generator control device (11 in FIG. 1) via a first inverter (7 in FIG. 1).

  The second motor generator 3 includes a stator 3c serving as a stator, a rotor 3b disposed inside the stator 3c, and an output shaft 3a that rotates integrally with the rotor 3b. The output shaft 3 a is connected to the third shaft 30 of the transmission 4 and rotates integrally with the third shaft 30. The case portion of the second motor generator 3 is fixed to the housing 34 of the transmission 4. The second motor generator 3 is electrically connected to a second motor generator control device (12 in FIG. 1) via a second inverter (8 in FIG. 1).

  The transmission 4 includes a first shaft 20, a drive gear 21, a drive gear 22, a switching mechanism 23, an actuator 24, a second shaft 25, a driven gear 26, a driven gear 27, a driven gear 28, and a drive gear. 29, a third shaft 30, a drive gear 31, a switching mechanism 32, an actuator 33, and a housing 34.

  The first shaft 20 is a shaft for inputting rotational power of the output shaft 2 a of the first motor generator 2. The first shaft 20 is rotatably supported by the housing 34. The first shaft 20 is connected to the output shaft 2a of the first motor generator 2 and rotates integrally with the output shaft 2a. The first shaft 20 rotatably supports the drive gear 21 and the drive gear 22. The rotational power of the first shaft 20 is transmitted to the drive gear 21 or the drive gear 22 according to the selection of the switching mechanism 23. The first shaft 20 is arranged coaxially with the third shaft 30 and is not connected to the third shaft 30.

  The drive gear 21 is a gear for driving the driven gear 26 to rotate. The drive gear 21 is rotatably supported by the first shaft 20. The drive gear 21 can be connected to the first shaft 20 by the selection of the switching mechanism 23. The drive gear 21 meshes with the driven gear 26. The drive gear 21 is a drive gear whose diameter is smaller than that of the drive gear 22 and whose gear stage is LO side.

  The drive gear 22 is a gear for driving the driven gear 27 to rotate. The drive gear 22 is rotatably supported by the first shaft 20. The drive gear 22 can be connected to the first shaft 20 by selection of the switching mechanism 23. The drive gear 22 meshes with the driven gear 27. The drive gear 22 has a diameter larger than that of the drive gear 21 and is a drive gear having a gear position on the HI side.

  The switching mechanism 23 is a mechanism for switching the connection between the first shaft 20 and the drive gear 21 or the drive gear 22. The switching operation of the switching mechanism 23 is performed by the actuator 24.

  The actuator 24 is a device that operates the switching mechanism 23. The actuator 24 is electrically connected to a transmission control device (10 in FIG. 1), and its operation is controlled by the transmission control device (10 in FIG. 1).

  The second shaft 25 is a shaft disposed in parallel with the first shaft 20. The second shaft 25 is rotatably supported by the housing 34. The second shaft 25 rotates integrally with the driven gear 26, the driven gear 27, the driven gear 28, and the drive gear 29.

  The driven gear 26 is a gear that is rotationally driven by the drive gear 21. The driven gear 26 rotates integrally with the second shaft 25. The driven gear 26 meshes with the drive gear 21. The driven gear 26 has a larger diameter than the driven gear 27 and is a driven gear whose gear position is LO.

  The driven gear 27 is a gear that is rotationally driven by the drive gear 22. The driven gear 27 rotates integrally with the second shaft 25. The driven gear 27 meshes with the drive gear 22. The driven gear 27 has a smaller diameter than the driven gear 26 and is a driven gear having a gear position on the HI side.

  The driven gear 28 is a gear that is rotationally driven by the drive gear 31. The driven gear 28 rotates integrally with the second shaft 25. The driven gear 28 meshes with the drive gear 31. The driven gear 28 is used to prevent torque loss at the time of shifting, and is used at the time of acceleration assist.

  The drive gear 29 is a gear for rotationally driving the ring gear 5 a of the differential device 5. The drive gear 29 rotates integrally with the second shaft 25. The drive gear 29 meshes with the ring gear 5 a of the differential device 5.

  The third shaft 30 is a shaft for inputting the rotational power of the output shaft 3 a of the second motor generator 3. The third shaft 30 is rotatably supported by the housing 34. The third shaft 30 is connected to the output shaft 3a of the second motor generator 3, and rotates integrally with the output shaft 3a. The third shaft 30 supports the drive gear 31 to be rotatable. The rotational power of the third shaft 30 is transmitted to the drive gear 31 by the selection of the switching mechanism 32. The third shaft 30 is arranged coaxially with the first shaft 20 and is not connected to the first shaft 20.

  The drive gear 31 is a gear for rotationally driving the driven gear 28. The drive gear 31 is rotatably supported by the third shaft 30. The drive gear 31 can be connected to the third shaft 30 by the selection of the switching mechanism 32. The drive gear 31 is engaged with the driven gear 28.

  The switching mechanism 32 is a mechanism for switching the connection between the third shaft 30 and the drive gear 31. The switching operation of the switching mechanism 32 is performed by the actuator 33.

  The actuator 33 is a device that operates the switching mechanism 32. The actuator 33 is electrically connected to a transmission control device (10 in FIG. 1), and its operation is controlled by the transmission control device (10 in FIG. 1).

  The housing 34 accommodates the gear unit of the transmission 4. The motor generators 2 and 3 are fixed to the housing 34. The housing 34 also houses the gear unit of the differential device 5.

  The differential device 5 drives the wheels 6 a and 6 b so as to be differentially driven by the rotational power from the drive gear 29 of the transmission 4. The differential 5 has a ring gear 5 a that meshes with the drive gear 29. The differential device 5 transmits the rotational power input from the ring gear 5a to the wheels 6a and 6b via the axles 5b and 5c in a differential manner.

  In the drive system of the vehicle drive apparatus (1 in FIG. 1) as described above, the rotational power of the output shaft 2a of the first motor generator 2 is the first shaft 20, the switching mechanism 23, the drive gear 21 or 22, the driven gear 26 or 27, the second shaft 25, the drive gear 29, and the differential 5 are transmitted to the wheels 6a, 6b. The LO gear (drive gear 21 and driven gear 26) is selected when a high torque is requested, and the HI gear (drive gear 22 and driven gear 27) is selected when a high rotational speed is requested. The first motor generator 2 is moved at a point where the HI / LO gear efficiency is improved.

  The rotational power of the output shaft 3 a of the second motor generator 3 is transmitted via the third shaft 30, the switching mechanism 32, the drive gear 31, the driven gear 28, the second shaft 25, the drive gear 29, and the differential device 5. It is transmitted to the wheels 6a and 6b. The rotational power of the second motor generator 3 is used to prevent torque loss during gear shifting. Further, during acceleration assist, the rotational power of the first motor generator 2 and the rotational power of the second motor generator 3 merge at the second shaft 25 of the second axis of the parallel triaxial structure.

  Next, the operation of the vehicle drive device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a time chart schematically showing changes in the rotation speeds of the first motor generator, the second motor generator, and the wheels at the time of shifting of the vehicle drive device according to the first embodiment of the present invention. FIG. 4 is a schematic diagram for explaining a process of determining output torques of the first motor generator and the second motor generator during acceleration assist of the vehicle drive device according to the first embodiment of the present invention. FIG. 5 is a table schematically showing the operation state of each traveling pattern of the vehicle drive device according to the first embodiment of the present invention.

[Torque loss prevention function]
First, the torque loss prevention function at the time of shifting will be described. Referring to FIG. 3, in order to prevent a decrease in wheel rotation speed due to torque loss caused by turning off the first motor generator (MG1; 2 in FIG. 2) during shifting (see the wheel rotation speed according to the comparative example between T1 and T2). , Without changing the wheel rotation speed by the torque of the second motor generator (MG2; 3 in FIG. 2) (increase or maintain the rotation speed; see the wheel rotation speed according to the first embodiment between T1 and T2), and make a smooth shift As a result, drivability is improved.

[Acceleration assist function]
Referring to FIG. 4, the first motor generator (MG1; 2 in FIG. 2) is independently operated with respect to the required motor torque, or the first motor generator (MG1; 2 in FIG. 2) and the second motor generator (MG2; Determine whether to move both 3) in FIG. Only when the fuel consumption (efficiency) is improved when both MG1 and MG2 are moved than when the MG1 is moved alone, the MG2 is assisted. The MG is moved at a point where the efficiency of the HI / LO gear is improved.

[Running pattern]
Referring to FIG. 5, in traveling pattern 1, the first motor generator (MG1; 2 in FIG. 2) is turned on (power running) in the low speed range (between stop and V1) at the time of acceleration and steady state, and the switching mechanism (23 in FIG. 2), the LO side (the first shaft 20 and the drive gear 21 in FIG. 2 are connected) is selected, the second motor generator (MG2; 3 in FIG. 2) is turned OFF, and the switching mechanism (FIG. 2) is selected. No. 32) is turned off. When acceleration assist is required, MG2 and the connection / disconnection state are set to ON (power running / contact).

  In traveling pattern 2, at the time of acceleration and steady state shifting, the first motor generator (MG1; 2 in FIG. 2) is turned OFF, the switching mechanism (23 in FIG. 2) is being switched (neutral), and the second motor generator (MG2; 3 in FIG. 2) is set to ON (power running), and the switching mechanism (32 in FIG. 2) is set to ON (contact).

  In traveling pattern 3, in the high speed range (between V1 and V2) when the vehicle is accelerating and steady, the first motor generator (MG1; 2 in FIG. 2) is turned on (powering), and the switching mechanism (23 in FIG. 2). To select the HI side (the first shaft 20 and the drive gear 22 in FIG. 2 are connected), the second motor generator (MG2; 3 in FIG. 2) is turned OFF, and the switching mechanism (32 in FIG. 2) is turned OFF ( )). When acceleration assist is required, MG2 and the connection / disconnection state are set to ON (power running / contact).

  In the running pattern 4, in the high speed range (between V2 and V1 ′) when the vehicle speed is reduced, the first motor generator (MG1; 2 in FIG. 2) is turned ON (regeneration), and the switching mechanism (23 in FIG. 2) is used. The HI side (the first shaft 20 and the drive gear 22 in FIG. 2 are connected) is selected, the second motor generator (MG2; 3 in FIG. 2) is turned on (regeneration), and the switching mechanism (32 in FIG. 2) is selected. ON (contact).

  In the traveling pattern 5, at the time of shifting during deceleration, the first motor generator (MG1; 2 in FIG. 2) is turned off, the switching mechanism (23 in FIG. 2) is being switched (neutral), and the second motor generator (MG2) 2) in FIG. 2 is turned on (regeneration), and the switching mechanism (32 in FIG. 2) is turned on.

  In the traveling pattern 6, in the low speed range when the vehicle speed is decelerating (between V1 ′ and the stop), the first motor generator (MG1; 2 in FIG. 2) is turned ON (regeneration), and the switching mechanism (23 in FIG. 2) is used. The LO side (the first shaft 20 and the drive gear 21 in FIG. 2 are connected) is selected, the second motor generator (MG2; 3 in FIG. 2) is turned on (regeneration), and the switching mechanism (32 in FIG. 2) is selected. ON (contact).

  In the running patterns 1 and 3, the second motor generator (MG2; 3 in FIG. 2) is OFF. However, since the switching mechanism (32 in FIG. 2) is OFF (disconnected), dragging by the MG2 is not performed. Does not occur.

  According to the first embodiment, torque loss is prevented by the driving force of the second motor generator (MG2; 3 in FIG. 2) at the time of shifting, and drivability can be improved. Since the meshing of both the LO gear and the HI gear is temporarily lost at the time of shifting (when both the HI gear and the LO gear are meshed, it becomes a brake), so only the first motor generator (MG1; 2 in FIG. 2) has a power source. Torque transmission is lost and torque loss occurs, but torque loss can be eliminated and the drivability can be improved by supplementing the torque at the time of shifting by the second motor generator (MG2; 3 in FIG. 2). it can.

  Further, according to the first embodiment, fuel efficiency (efficiency) can be improved by driving assistance of the second motor generator (MG2; 3 in FIG. 2) during acceleration. If only the first motor generator (MG1; 2 in FIG. 2) has a power source, it is driven at a point (region) where the efficiency is low and the fuel consumption is deteriorated, but when driving at a point where the efficiency of MG1 is bad, By driving MG2, MG1 can be driven with better efficiency, and fuel efficiency (efficiency) can be improved.

  Furthermore, according to the first embodiment, by providing a switching mechanism (32 in FIG. 2) that enables the rotational power of the second motor generator (MG2; 3 in FIG. 2) to be disconnected in the transmission 4, MG2 is turned off. The drag at the time can be eliminated, and the fuel efficiency by assist driving and regeneration can be improved.

  A vehicle drive apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 6 is a skeleton diagram schematically showing the configuration of the drive system of the vehicle drive device according to the second embodiment of the present invention. FIG. 7 is a table schematically showing the operation states of the respective travel patterns of the vehicle drive device according to the second embodiment of the present invention.

  The second embodiment is a modification of the first embodiment. In the transmission 4, the switching mechanism (32 in FIG. 2) that enables the rotational power of the second motor generator 3 to be disconnected is stopped in the transmission 4, and a one-way clutch is used instead. 36 is used. Other configurations are the same as those of the first embodiment.

  The one-way clutch 36 is a clutch that allows the drive gear 31 to rotate only in one direction with respect to the third shaft 30. The one-way clutch 36 transmits the rotational power of the third shaft 30 to the drive gear 31 at the time of forward assist when the second motor generator 3 is driven, and the rotational power of the drive gear 31 at the time of forward regeneration regenerated by the second motor generator 3. 3 is transmitted to the shaft 30. The one-way clutch 36 does not transmit power between the drive gear 31 and the third shaft 30 when the second motor generator 3 is OFF at the time of forward movement, and the second motor when the second motor generator 3 is unnecessary. It is possible to eliminate dragging of the generator 3.

  The vehicle drive device configured as described above operates as follows.

  Referring to FIG. 7, in traveling pattern 1, in the low speed range during acceleration (between stop and V1), the first motor generator (MG1; 2 in FIG. 6) is turned on (power running), and the switching mechanism (FIG. 6 of 23) selects the LO side (the first shaft 20 and the drive gear 21 in FIG. 6 are connected), the second motor generator (MG2; 3 in FIG. 6) is turned OFF, and the one-way clutch (36 in FIG. 6) is selected. ) Is automatically turned off. When acceleration assist is required, MG2 is turned on (power running), and the one-way clutch (36 in FIG. 6) is automatically turned on (contacted).

  In travel pattern 2, at the time of shifting during acceleration, the first motor generator (MG1; 2 in FIG. 6) is turned OFF, the switching mechanism (23 in FIG. 6) is being switched (neutral), and the second motor generator (MG2) ; 3) in FIG. 6 is turned ON (power running), and the one-way clutch (36 in FIG. 6) is automatically turned ON.

  In traveling pattern 3, in the high speed range (between V1 and V2) when the vehicle is accelerating, the first motor generator (MG1; 2 in FIG. 6) is turned on (power running), and the switching mechanism (23 in FIG. 6) is set to HI. Side (connecting the first shaft 20 and the drive gear 22 in FIG. 6), the second motor generator (MG2; 3 in FIG. 6) is turned off, and the one-way clutch (36 in FIG. 6) is automatically turned off. (Decline) When acceleration assist is required, MG2 is turned on (power running), and the one-way clutch (36 in FIG. 6) is automatically turned on (contacted).

  In the running pattern 4, in the high speed range (between V2 and V1 ′) when the vehicle speed is decelerated, the first motor generator (MG1; 2 in FIG. 6) is turned on (regeneration), and the switching mechanism (23 in FIG. 6) is used. The HI side (connecting the first shaft 20 and the drive gear 22 in FIG. 6) is selected, the second motor generator (MG2; 3 in FIG. 6) is turned OFF, and the one-way clutch (36 in FIG. 6) is automatically activated. OFF (OFF).

  In the traveling pattern 5, at the time of speed reduction, the first motor generator (MG1; 2 in FIG. 6) is turned OFF, the switching mechanism (23 in FIG. 6) is being switched (neutral), and the second motor generator (MG2) ; 3) in FIG. 6 is turned on (regeneration), and the one-way clutch (36 in FIG. 6) is automatically turned on.

  In the traveling pattern 6, in the low speed range when the vehicle speed is decelerated (between V1 ′ and the stop), the first motor generator (MG1; 2 in FIG. 6) is turned on (regeneration), and the switching mechanism (23 in FIG. 6) is used. The LO side (connecting the first shaft 20 and the drive gear 21 in FIG. 6) is selected, the second motor generator (MG2; 3 in FIG. 6) is turned off, and the one-way clutch (36 in FIG. 6) is automatically activated. OFF (OFF).

  In traveling patterns 1, 3, 4, and 6, the second motor generator (MG2; 3 in FIG. 6) is OFF, but the one-way clutch (36 in FIG. 6) is automatically OFF (disconnected). Therefore, drag by MG2 does not occur.

  According to the second embodiment, as in the first embodiment, torque loss is prevented by the driving force of the second motor generator (MG2; 3 in FIG. 6) at the time of shifting, and drivability can be improved. The fuel consumption (efficiency) can be improved by driving assist of the second motor generator (MG2; 3 in FIG. 6). Further, according to the second embodiment, the transmission 4 is provided with the one-way clutch (36 in FIG. 6) that allows the rotational power of the second motor generator (MG2; 3 in FIG. 6) to be disconnected. The drag at the time can be eliminated, and the fuel efficiency by assist driving and regeneration can be improved.

  A vehicle drive apparatus according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 8 is a skeleton diagram schematically showing the configuration of the drive system of the vehicle drive device according to the third embodiment of the present invention. FIG. 9 is a table schematically showing the operation states of the respective travel patterns of the vehicle drive device according to the third embodiment of the present invention.

  The third embodiment is a modification of the first embodiment, and uses the induction motor 15 instead of the second motor generator (3 in FIG. 2) and stops using the switching mechanism (32 in FIG. 2) in the transmission 4. The drive gear 31 is configured to rotate integrally with the third shaft 30. Other configurations are the same as those of the first embodiment.

  The induction motor 15 is a motor in which an induction current is generated in the rotor 15b (rotor) of the electric conductor by a rotating magnetic field generated by the stator 15c (stator), and a rotational torque corresponding to the slip is generated. The induction motor 15 has an output shaft 15a that rotates integrally with the rotor 15b. The output shaft 15 a is connected to the third shaft 30 of the transmission 4 and rotates integrally with the third shaft 30. A case portion of the induction motor 15 is fixed to the housing 34 of the transmission 4. The induction motor 15 is electrically connected to a second motor generator control device (12 in FIG. 1) via a second inverter (8 in FIG. 1).

  The vehicle drive device configured as described above operates as follows.

  Referring to FIG. 9, in traveling pattern 1, in the low speed range during acceleration (between stop and V1), the first motor generator (MG1; 2 in FIG. 8) is turned on (power running), and a switching mechanism (FIG. 8 (23), the LO side (the first shaft 20 and the drive gear 21 in FIG. 8 are connected) is selected, and the induction motor (IM; 15 in FIG. 8) is turned OFF. When acceleration assistance is required, IM is turned on (power running).

  In traveling pattern 2, at the time of shifting during acceleration, the first motor generator (MG1; 2 in FIG. 8) is turned OFF, the switching mechanism (23 in FIG. 8) is being switched (neutral), and the induction motor (IM; FIG. 8) 15) is set to ON (power running).

  In travel pattern 3, in the high speed range (between V1 and V2) during acceleration, the first motor generator (MG1; 2 in FIG. 8) is turned on (powering), and the switching mechanism (23 in FIG. 8) is set to HI. Side (connecting the first shaft 20 and the drive gear 22 in FIG. 8) is selected, and the induction motor (IM; 15 in FIG. 8) is turned OFF. When acceleration assistance is required, IM is turned on (power running).

  In the running pattern 4, in the high speed range (between V2 and V1 ′) when the vehicle speed is reduced, the first motor generator (MG1; 2 in FIG. 8) is turned ON (regeneration), and the switching mechanism (23 in FIG. 8) is used. The HI side (the first shaft 20 and the drive gear 22 in FIG. 8 are connected) is selected, and the induction motor (IM; 15 in FIG. 8) is turned ON (regeneration).

  In the traveling pattern 5, at the time of shifting during deceleration, the first motor generator (MG1; 2 in FIG. 8) is turned OFF, the switching mechanism (23 in FIG. 8) is being switched (neutral), and the induction motor (IM; FIG. Set 8 (15) to ON (regeneration).

  In the traveling pattern 6, in the low speed range when the vehicle speed is decelerated (between V1 ′ and the stop), the first motor generator (MG1; 2 in FIG. 8) is turned on (regeneration), and the switching mechanism (23 in FIG. 8) is used. The LO side (the first shaft 20 and the drive gear 21 in FIG. 8 are connected) is selected, and the induction motor (IM; 15 in FIG. 8) is turned ON (regeneration).

  In the travel patterns 1 and 3, the induction motor (IM; 15 in FIG. 8) is OFF, but drag is not generated because the induction motor is used.

  According to the third embodiment, as in the first embodiment, torque loss at the time of shifting can be prevented and drivability can be improved, and driving assistance of the induction motor (IM; 15 in FIG. 8) during acceleration Fuel consumption (efficiency) can be improved. Further, according to the third embodiment, a mechanism for separating the rotational power of IM in the transmission 4 by using an induction motor (IM; 15 in FIG. 8) instead of the second motor generator (MG2; 3 in FIG. 2). Even without providing, dragging when IM is OFF can be eliminated, and fuel efficiency by assist drive and regeneration can be improved.

  A vehicle drive apparatus according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 10 is a skeleton diagram schematically illustrating the configuration of the drive system of the vehicle drive device according to the fourth embodiment of the present invention.

  The fourth embodiment is a modification of the first embodiment, and the third shaft 30 connected to the output shaft 3 a of the second motor generator 3 is stopped from being arranged coaxially with the first shaft 20. And the third shaft 30 and the second shaft 25 can be connected by a switching mechanism 32. Accordingly, the drive gear (31 in FIG. 2) and the driven gear (28 in FIG. 2) in Example 1 were eliminated. Other configurations and operations are the same as those in the first embodiment. Further, the fourth embodiment can be modified as in the second and third embodiments.

  According to the fourth embodiment, the same effect as that of the first embodiment is obtained, and the configuration of the transmission 4 is simplified by eliminating the drive gear (31 in FIG. 2) and the driven gear (28 in FIG. 2) in the first embodiment. Thus, the cost can be reduced as compared with the first embodiment.

  A vehicle drive device according to a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a skeleton diagram schematically showing the configuration of the drive system of the vehicle drive device according to the fifth embodiment of the present invention.

  The fifth embodiment is a modification of the first embodiment. The third shaft 30 connected to the output shaft 3 a of the second motor generator 3 is stopped from being arranged coaxially with the first shaft 20, and the second shaft 25. And the third shaft 30 and the second shaft 25 can be connected by a switching mechanism 32. Accordingly, the drive gear (31 in FIG. 2) and the driven gear (28 in FIG. 2) in Example 1 were eliminated. Other configurations and operations are the same as those in the first embodiment. Further, the fifth embodiment can be modified as in the second and third embodiments.

  According to the fifth embodiment, the same effect as that of the first embodiment is obtained, and the configuration of the transmission 4 is simplified by eliminating the drive gear (31 in FIG. 2) and the driven gear (28 in FIG. 2) in the first embodiment. Thus, the cost can be reduced as compared with the first embodiment.

  A vehicle drive apparatus according to Embodiment 6 of the present invention will be described with reference to the drawings. FIG. 12 is a skeleton diagram schematically illustrating the configuration of the drive system of the vehicle drive device according to the sixth embodiment of the present invention.

  The sixth embodiment is a modification of the first embodiment, and the configuration of the transmission 4 and the differential device 5 is not changed to the three-axis configuration, but the two-axis configuration is used, and the axles 5b and 5c of the differential device 5 are shifted. A third shaft 30 that is arranged coaxially with the first shaft 20 of the machine 4, passes the axle 5 b inside the hollow first shaft 20 and the output shaft 2 a, and is connected to the output shaft 3 a of the second motor generator 3. It is arranged coaxially with the second shaft 25 and on the left side of the second shaft 25 so that the third shaft 30 and the second shaft 25 can be connected by the switching mechanism 32. Accordingly, the drive gear (31 in FIG. 2) and the driven gear (28 in FIG. 2) in Example 1 were eliminated. Other configurations and operations are the same as those in the first embodiment. Further, the sixth embodiment can be modified as in the second and third embodiments.

  According to the sixth embodiment, the same effects as in the first embodiment are obtained, and the axles 5b and 5c of the differential 5 are arranged coaxially with the first shaft 20 of the transmission 4, so that the hollow first shaft 20 and the output are provided. By inserting the axle 5b inside the shaft 2a, the configurations of the transmission 4 and the differential device 5 can be made to be a biaxial configuration, and the configurations of the transmission 4 and the differential device 5 are smaller than those of the first embodiment. can do.

  A vehicle drive apparatus according to Embodiment 7 of the present invention will be described with reference to the drawings. FIG. 13 is a skeleton diagram schematically showing the configuration of the drive system of the vehicle drive device according to the seventh embodiment of the present invention.

(Constitution)
The seventh embodiment is a modification of the sixth embodiment, in which a third shaft 30 connected to the output shaft 3a of the second motor generator 3 is arranged coaxially with the second shaft 25 and on the right side of the second shaft 25. The three shaft 30 and the second shaft 25 can be connected by a switching mechanism 32. Other configurations are the same as those in the sixth embodiment.

  According to the seventh embodiment, the same effect as the sixth embodiment is obtained.

  A vehicle drive apparatus according to Embodiment 8 of the present invention will be described with reference to the drawings. FIG. 14 is a skeleton diagram schematically illustrating the configuration of the drive system of the vehicle drive device according to the eighth embodiment of the present invention.

  The eighth embodiment is a modification of the sixth embodiment, in which a fourth shaft 38 parallel to the first shaft 20 and the second shaft 25 is added, and a drive gear 39 that meshes with the driven gear 26 (27 or 28 is acceptable). In addition, the drive gear 39 is rotated integrally with the fourth shaft 38, and the third shaft 30 connected to the output shaft 3a of the second motor generator 3 is coaxial with the fourth shaft 38 and on the left side of the fourth shaft 38 ( The third shaft 30 and the fourth shaft 38 can be connected by the switching mechanism 32. Other configurations are the same as those in the sixth embodiment.

  According to the eighth embodiment, as in the sixth embodiment (first embodiment to be cited), torque loss at the time of shifting can be prevented, drivability can be improved, and driving assist of the second motor generator 3 at the time of acceleration is achieved. Thus, fuel consumption (efficiency) can be improved.

  A vehicle drive device according to Embodiment 9 of the present invention will be described with reference to the drawings. FIG. 15 is a skeleton diagram schematically illustrating the configuration of the drive system of the vehicle drive device according to the ninth embodiment of the present invention.

  The ninth embodiment is a modification of the sixth embodiment, in which a fourth shaft 38 parallel to the first shaft 20 and the second shaft 25 is added, and the ring gear 5a of the differential device 5 (the drive gears 21 and 22 are also possible). And the drive gear 39 is rotated integrally with the fourth shaft 38. The third shaft 30 connected to the output shaft 3a of the second motor generator 3 is coaxial with the fourth shaft 38. The third shaft 30 and the fourth shaft 38 are arranged on the right side (or the left side) of the fourth shaft 38 and can be connected by the switching mechanism 32. Other configurations are the same as those in the sixth embodiment.

  According to the ninth embodiment, similarly to the sixth embodiment (embodiment 1 to be cited), torque loss at the time of shifting can be prevented, drivability can be improved, and driving assistance of the second motor generator 3 at the time of acceleration is achieved. Thus, fuel consumption (efficiency) can be improved.

  It should be noted that the embodiments and examples may be changed and adjusted within the scope of the entire disclosure (including claims and drawings) of the present invention and based on the basic technical concept. Various disclosed elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) can be combined or selected within the scope of the claims of the present invention. . That is, the present invention naturally includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the drawings, and the technical idea.

DESCRIPTION OF SYMBOLS 1 Vehicle drive device 2 1st motor generator 2a Output shaft 2b Rotor 2c Stator 3 2nd motor generator 3a Output shaft 3b Rotor 3c Stator 4 Transmission 5 Differential device 5a Ring gear 5b, 5c Axle 6a, 6b Wheel 7 1st inverter 8 Second inverter 9 Battery 10 Transmission control device 11 First motor generator control device 12 Second motor generator control device 13 Battery control device 14 Main control device 15 Induction motor 15a Output shaft 15b Rotor 15c Stator 16 Sensor 20 First shaft 21 Drive Gear 22 Drive gear 23 Switching mechanism 24 Actuator 25 Second shaft 26 Driven gear 27 Driven gear 28 Driven gear 29 Drive gear 30 Third shaft 31 Drive gear 32 Switching machine Structure 33 Actuator 34 Housing 36 One-way clutch 38 Fourth shaft 39 Drive gear

Claims (12)

A first motor generator for outputting rotational power;
A transmission capable of shifting and outputting the rotational power output from the first motor generator, and capable of switching a gear ratio;
A differential device that differentially drives the two wheels by the rotational power output from the transmission;
A second motor generator that outputs rotational power to the differential through the transmission;
With
The transmission is configured to transmit the rotational power output from the second motor generator to the differential device when the transmission gear ratio of the rotational power output from the first motor generator is switched. The vehicle drive device characterized by the above-mentioned.   The transmission is configured to transmit the rotational power output from the second motor generator to the differential device when shifting and outputting the rotational power output from the first motor generator. The vehicle drive device according to claim 1, wherein   The transmission includes a switching mechanism capable of switching between a state in which the rotational power output from the second motor generator is transmitted and a state in which it is not transmitted in a power transmission path from the second motor generator to the differential device. The vehicle drive device according to claim 1 or 2, wherein   The transmission includes a one-way clutch that allows rotational power output from the second motor generator only in one direction in a power transmission path from the second motor generator to the differential device. Item 3. The vehicle drive device according to Item 1 or 2.   The vehicle drive device according to claim 1, wherein the transmission is configured to constantly transmit the rotational power output from the second motor generator to the differential device.   The vehicle drive device according to claim 5, wherein the second motor generator is an induction motor. The transmission is
A first shaft to which the rotational power output from the first motor generator is input;
A second shaft arranged in parallel to the first shaft and outputting rotational power toward the differential device;
Another switching mechanism for switching the transmission gear ratio of the rotational power transmitted from the first shaft to the second shaft;
Thirdly arranged in parallel to the first shaft, the rotational power output from the second motor generator is input, and the rotational power is output toward the second shaft or the differential device. A shaft,
The vehicle drive device according to any one of claims 1 to 6, further comprising:   The vehicle drive device according to claim 7, wherein the third shaft is disposed coaxially with the first shaft and outputs rotational power toward the second shaft.   The vehicle drive apparatus according to claim 7, wherein the third shaft is disposed coaxially with the second shaft and outputs rotational power toward the second shaft. The output shaft of the first shaft and the first motor generator is a hollow shaft,
The vehicle drive apparatus according to claim 7 or 9, wherein an axle for transmitting rotational power from the differential to the wheel on one side is inserted inside the hollow shaft. A fourth shaft that is arranged in parallel to the first shaft and outputs rotational power toward the second shaft;
The vehicle drive apparatus according to claim 10, wherein the third shaft is arranged coaxially with the fourth shaft and outputs rotational power to the second shaft via the fourth shaft. A fourth shaft that is arranged in parallel with the first shaft and outputs rotational power toward the differential;
11. The vehicle drive device according to claim 10, wherein the third shaft is arranged coaxially with the fourth shaft and outputs rotational power to the differential device via the fourth shaft.

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