Drive unit

Abstract

To drive a pump at an appropriate time.SOLUTION: A driving unit 100 comprises a first electric motor 2, a fluid coupling 3, a pump 11, a second electric motor 12, and a control unit 15. The first electric motor 2 is constituted so as to drive driving wheels 101. Torque from the first electric motor 2 is inputted to the fluid coupling 3. The pump 11 is constituted so as to supply working fluid into the fluid coupling 3. The second electric motor 12 is constituted so as to drive the pump 11. The control unit 15 controls the second electric motor 12 on the basis of at least one of an input / output rotation ratio of the fluid coupling 3, a temperature of the working fluid in the fluid coupling 3, and an amount of the working fluid in the fluid coupling 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a drive unit.

Background Art

[0002] In recent years, electric vehicles having a torque converter have been proposed. For example, in the electric vehicle described in Patent Document 1, the torque from the electric motor is transmitted to the drive wheels via the torque converter. Further, the electric vehicle described in Patent Document 1 includes an oil pump for supplying oil to the torque converter. This oil pump is connected to the impeller of the torque converter and is driven by the rotation of the impeller. That is, the oil pump is driven by the electric motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electric vehicle configured as described above, the oil pump is driven by an electric motor for driving the drive wheels. Therefore, during running, the oil pump is always in an operating state.

[0005] An object of the present invention is to drive the pump at an appropriate time.

Means for Solving the Problems

[0006] A drive unit according to an aspect of the present invention includes a first electric motor, a fluid coupling, a pump, a second electric motor, and a control unit. The first electric motor is configured to drive drive wheels. The fluid coupling receives torque from the first electric motor. The pump is configured to supply a working fluid into the fluid coupling. The second electric motor is configured to drive the pump. The control unit controls the second electric motor based on at least one of an input / output rotation ratio of the fluid coupling, a temperature of the working fluid in the fluid coupling, and an amount of the working fluid in the fluid coupling.

[0007] According to this configuration, the pump is driven by the second electric motor instead of the first electric motor for driving the drive wheels. Therefore, the pump does not always operate during running. Further, the control unit controls the second electric motor based on at least one of an input / output rotation ratio of the fluid coupling, a temperature of the working fluid in the fluid coupling, and an amount of the working fluid in the fluid coupling. Therefore, the pump can be driven at an appropriate time.

[0008] Preferably, the drive unit further includes a tank. The tank stores the working fluid supplied to the fluid coupling. The control unit determines the amount of the working fluid in the fluid coupling based on the amount of the working fluid in the tank.

[0009] Preferably, the control unit controls the second electric motor based on the rotation direction of the first electric motor.

[0010] Preferably, the drive unit further includes a battery temperature adjustment circuit, a working fluid cooler, a first flow path, a second flow path, and a switching valve. The battery temperature adjustment circuit is configured to adjust the temperature of the battery with the working fluid. The working fluid cooler is configured to cool the working fluid. The first flow path is configured to supply the working fluid to the battery temperature adjustment circuit via the working fluid cooler. The second flow path is configured to supply the working fluid to the battery temperature adjustment circuit without passing through the working fluid cooler. The switching valve is configured to switch the flow path for supplying the working fluid between the first flow path and the second flow path.

[0011] Preferably, the control unit controls the switching valve based on the outside air temperature.

Effect of the Invention

[0012] According to the present invention, the oil pump can be driven at an appropriate time.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the drive unit will be described with reference to the drawings. FIG. 1 is a schematic diagram of the drive unit according to the present embodiment. In the following description, the axial direction is the direction in which the rotation axes O of the first electric motor 2 and the torque converter 3 extend. The circumferential direction is the circumferential direction of a circle centered on the rotation axis O, and the radial direction is the radial direction of a circle centered on the rotation axis O. Also, the forward rotation is the rotation when the vehicle moves forward, and the reverse rotation is the rotation when the vehicle moves backward.

[0015] [Drive Unit 100] As shown in FIG. 1, the drive unit 100 includes a first electric motor 2, a torque converter 3 (an example of a fluid coupling), an input shaft 5, an output shaft 6, a speed reducer 7, a torque converter case 8, a pump 11, a second electric motor 12, a tank 13, and a control unit 15. This drive unit 100 is mounted on, for example, an electric vehicle. The drive unit 100 is configured to drive the drive wheels 101.

[0016] [First Electric Motor 2] The first electric motor 2 is configured to drive the drive wheels 101. The first electric motor 2 has a motor case 21, a stator 22, and a rotor 23. The first electric motor 2 in the present embodiment is a so-called inner rotor type motor. The motor case 21 is fixed to the vehicle body frame or the like and is non-rotatable.

[0017] The stator 22 is fixed to the inner peripheral surface of the motor case 21. The stator 22 is non-rotatable. The rotor 23 rotates around the rotation axis O. The rotor 23 is disposed inside the stator 22 in the radial direction. The first electric motor 2 rotates forward and backward. When the first electric motor 2 rotates forward, the vehicle moves forward. When the first electric motor 2 rotates backward, the vehicle moves backward.

[0018] <Torque converter 3> The torque converter 3 is disposed at an axial distance from the first electric motor 2. A speed reducer 7 is disposed between the torque converter 3 and the first electric motor 2. In the axial direction, the first electric motor 2, the speed reducer 7, and the torque converter 3 are arranged in this order.

[0019] The rotation axis O of the torque converter 3 substantially coincides with the rotation axis O of the first electric motor 2. The torque converter 3 receives the torque from the first electric motor 2. The torque converter 3 amplifies the torque from the first electric motor 2 and outputs it to the speed reducer 7.

[0020] As shown in FIG. 2, the torque converter 3 has a cover 31, an impeller 32, a turbine 33, a stator 34, a first one-way clutch 35, and a second one-way clutch 36. Further, the torque converter 3 further has a centrifugal lock-up clutch 37. In the present embodiment, the outer shell of the torque converter 3 is constituted by the cover 31 and an impeller shell 321 described later. The torque converter 3 transmits torque through a working fluid.

[0021] The torque converter 3 has an impeller 32 disposed on the side of the first electric motor 2 (the left side in FIG. 2), and a cover 31 disposed on the side opposite to the first electric motor 2 (the right side in FIG. 2). This torque converter 3 is housed in a torque converter case 8. The torque converter 3 is filled with a working fluid. The working fluid is, for example, hydraulic oil.

[0022] The cover 31 receives the torque from the first electric motor 2. The cover 31 rotates by the torque from the first electric motor 2. The cover 31 is fixed to the input shaft 5. For example, the cover 31 has a spline hole, and the input shaft 5 is spline-fitted into the spline hole of the cover 31. Therefore, the cover 31 rotates integrally with the input shaft 5. The cover 31 is disposed so as to cover the turbine 33.

[0023] The cover 31 has a disk portion 311, a cylindrical portion 312, and a cover hub 313. The disk portion 311 has an opening at the center. The cylindrical portion 312 extends from the outer peripheral end of the disk portion 311 toward the first electric motor 2 side. The disk portion 311 and the cylindrical portion 312 are formed of one member.

[0024] The cover hub 313 is fixed to the inner peripheral end of the disk portion 311. In the present embodiment, the cover hub 313 is formed of a member different from the disk portion 311, but may be formed of one member with the disk portion 311.

[0025] The cover hub 313 has a first boss portion 313a, a first flange portion 313b, and a protruding portion 313c. The first boss portion 313a, the first flange portion 313b, and the protruding portion 313c are formed of one member.

[0026] The first boss portion 313a is cylindrical and has a spline hole. The input shaft 5 is spline-fitted to the first boss portion 313a. The first boss portion 313a is rotatably supported by a bearing member (not shown) in the torque converter case 8. The first boss portion 313a extends axially from the first flange portion 313b to the side opposite to the first electric motor 2.

[0027] The first flange portion 313b extends radially outward from the first boss portion 313a. Specifically, the first flange portion 313b extends radially outward from the end portion of the first boss portion 313a on the side of the first electric motor 2. A disk portion 311 is fixed to the outer peripheral end portion of the first flange portion 313b.

[0028] The protruding portion 313c extends axially from the first flange portion 313b. The protruding portion 313c extends toward the first electric motor 2. The protruding portion 313c extends from the outer peripheral end portion of the first flange portion 313b. The protruding portion 313c is cylindrical.

[0029] The impeller 32 rotates integrally with the cover 31. Torque from the first electric motor 2 is input to the impeller 32 via the cover 31. The impeller 32 is fixed to the cover 31. The impeller 32 has an impeller shell 321, a plurality of impeller blades 322, and an impeller hub 323.

[0030] The impeller shell 321 is fixed to the cover 31. The plurality of impeller blades 322 are attached to the inner surface of the impeller shell 321.

[0031] The impeller hub 323 is attached to the inner peripheral end portion of the impeller shell 321. In this embodiment, the impeller hub 323 is formed of one member with the impeller shell 321, but it may be formed of a separate member from the impeller shell 321.

[0032] The impeller hub 323 has a second boss portion 323a and a second flange portion 323b. The second flange portion 323b extends radially outward from the second boss portion 323a. The second boss portion 323a is cylindrical and extends in the axial direction. The second boss portion 323a is rotatably supported by a torque converter case 8 via a bearing member (not shown).

[0033] A fixed shaft 104 (an example of a shaft member) extends in the axial direction inside the second boss portion 323a. The fixed shaft 104 is cylindrical, and an output shaft 6 extends in the axial direction inside the fixed shaft 104. Further, the fixed shaft 104 extends from, for example, a transmission case 72 or a torque converter case 8. The fixed shaft 104 is non-rotatable. That is, the fixed shaft 104 rotates relative to the torque converter 3.

[0034] The turbine 33 is arranged to face the impeller 32. Specifically, the turbine 33 faces the impeller 32 in the axial direction. Torque is transmitted from the impeller 32 to the turbine 33 via the working fluid.

[0035] The turbine 33 has a turbine shell 331, a plurality of turbine blades 332, and a turbine hub 333. The turbine blades 332 are fixed to the inner surface of the turbine shell 331.

[0036] The turbine hub 333 is fixed to the inner peripheral end portion of the turbine shell 331. For example, the turbine hub 333 is fixed to the turbine shell 331 by rivets. In the present embodiment, the turbine hub 333 is formed of a separate member from the turbine shell 331, but may be formed of one member with the turbine shell 331.

[0037] The output shaft 6 is attached to the turbine hub 333. Specifically, the output shaft 6 is spline-fitted to the turbine hub 333. The turbine hub 333 rotates integrally with the output shaft 6.

[0038] The turbine hub 333 has a third boss portion 333a and a third flange portion 333b. The third boss portion 333a and the third flange portion 333b are formed of a single member.

[0039] The third boss portion 333a is cylindrical and has a spline hole. The output shaft 6 is spline-fitted to the third boss portion 333a. The third boss portion 333a extends in the axial direction from the third flange portion 333b to the side opposite to the first electric motor 2. That is, the third boss portion 333a extends in the axial direction from the third flange portion 333b toward the cover hub 313.

[0040] The third boss portion 333a is arranged at a distance from the protruding portion 313c in the radial direction. That is, the protruding portion 313c is arranged outside the third boss portion 333a in the radial direction. A first one-way clutch 35 is arranged between the third boss portion 333a and the protruding portion 313c. In a state where the first one-way clutch 35 is not provided, the outer peripheral surface of the third boss portion 333a and the inner peripheral surface of the protruding portion 313c face each other.

[0041] The third flange portion 333b extends radially outward from the third boss portion 333a. Specifically, the third flange portion 333b extends radially outward from the end portion of the third boss portion 333a on the first electric motor 2 side. A turbine shell 331 is fixed to the outer peripheral end portion of the third flange portion 333b by means such as rivets.

[0042] The stator 34 is configured to rectify the oil returning from the turbine 33 to the impeller 32. The stator 34 is rotatable around the rotation axis O. For example, the stator 34 is supported by a fixed shaft 104 via a second one-way clutch 36. The stator 34 is arranged between the impeller 32 and the turbine 33 in the axial direction.

[0043] The stator 34 has a disk-shaped stator carrier 341 and a plurality of stator blades 342 attached to the outer peripheral surface thereof.

[0044] The first one-way clutch 35 is disposed between the cover 31 and the turbine 33. The first one-way clutch 35 allows the cover 31 to rotate relative to the turbine 33 in the forward rotation direction. That is, when the first electric motor 2 rotates forward so that the vehicle moves forward, the first one-way clutch 35 is configured such that the cover 31 rotates relative to the turbine 33. Therefore, when the vehicle moves forward, the first one-way clutch 35 does not transmit torque from the cover 31 to the turbine 33.

[0045] On the other hand, the first one-way clutch 35 causes the cover 31 to rotate integrally with the turbine 33 in the reverse rotation direction. That is, when the first electric motor 2 rotates in the reverse direction so that the vehicle moves backward, the first one-way clutch 35 is configured such that the cover 31 rotates integrally with the turbine 33. Therefore, when the vehicle moves backward, the first one-way clutch 35 transmits torque from the cover 31 to the turbine 33.

[0046] The second one-way clutch 36 is disposed between the fixed shaft 104 and the stator 34. The second one-way clutch 36 is configured to allow the stator 34 to rotate in the forward rotation direction. On the other hand, the second one-way clutch 36 prevents the stator 34 from rotating in the reverse rotation direction. By this stator 34, torque is amplified and transmitted from the impeller 32 to the turbine 33.

[0047] The centrifugal lock-up clutch 37 is configured to operate by the rotation of the torque converter 3. That is, the centrifugal lock-up clutch 37 does not operate by the fluid pressure of the working fluid. The centrifugal lock-up clutch 37 is attached to the turbine 33. The centrifugal lock-up clutch 37 rotates integrally with the turbine 33.

[0048] The centrifugal lock-up clutch 37 is configured to connect the impeller 32 and the turbine 33 without an operating fluid by the centrifugal force generated by the rotation of the turbine 33. The centrifugal lock-up clutch 37 connects the impeller 32 and the turbine 33 via the cover 31. Specifically, the centrifugal lock-up clutch 37 is configured to transmit torque from the cover 31 to the turbine 33 when the turbine 33 reaches a predetermined rotational speed or higher.

[0049] The centrifugal lock-up clutch 37 has a plurality of centrifugal members 371 and a friction material 372. The friction material 372 is attached to the outer peripheral surface of the centrifugal member 371. The centrifugal members 371 are arranged to be movable in the radial direction. The centrifugal members 371 are arranged to be immovable in the circumferential direction. Therefore, the centrifugal members 371 rotate together with the turbine 33 and move radially outward by the centrifugal force.

[0050] When the rotational speed of the turbine 33 reaches a predetermined rotational speed or higher, the centrifugal members 371 move radially outward, and the friction material 372 comes into frictional engagement with the inner peripheral surface of the cylindrical portion 312 of the cover 31. As a result, the centrifugal lock-up clutch 37 is turned on, and the torque from the cover 31 is transmitted to the turbine 33 via the centrifugal lock-up clutch 37.

[0051] When the rotational speed of the turbine 33 is less than the predetermined rotational speed, the centrifugal members 371 move radially inward, and the frictional engagement between the friction material 372 and the inner peripheral surface of the cylindrical portion 312 of the cover 31 is released. As a result, the centrifugal lock-up clutch 37 is turned off, and the torque from the cover 31 is not transmitted to the turbine 33 via the centrifugal lock-up clutch 37. That is, the torque from the cover 31 is transmitted to the impeller 32 and then transmitted to the turbine 33 via the operating fluid.

[0052] <Input shaft 5> As shown in FIGS. 1 and 2, the input shaft 5 extends from the first electric motor 2. Specifically, the input shaft 5 extends from the rotor 23 of the first electric motor 2. If the first electric motor 2 has an output shaft, the input shaft 5 is attached to the output shaft of the first electric motor 2. The rotation axis of the input shaft 5 is substantially collinear with the rotation axis of the first electric motor 2 and the rotation axis of the torque converter 3.

[0053] The input shaft 5 inputs the torque from the first electric motor 2 to the torque converter 3. The input shaft 5 is connected to the impeller 32 of the torque converter 3. Specifically, the input shaft 5 is connected to the impeller 32 via the cover 31. The tip of the input shaft 5 is attached to the cover hub 313 of the torque converter 3.

[0054] The input shaft 5 extends inside the output shaft 6. The input shaft 5 is solid.

[0055] <Output shaft 6> The output shaft 6 outputs the torque from the torque converter 3. The output shaft 6 outputs the torque from the torque converter 3 to the speed reducer 7. The output shaft 6 extends from the torque converter 3 toward the first electric motor 2.

[0056] The output shaft 6 is cylindrical. The input shaft 5 extends inside this output shaft 6. One end (the right end in FIG. 2) of the output shaft 6 is attached to the turbine 33 of the torque converter 3. Also, a gear 71 of the speed reducer 7 is attached to the other end of the output shaft 6. The output shaft 6 is rotatably supported, for example, by a bearing member or the like in the transmission case 72.

[0057] <Speed reducer 7> As shown in FIG. 1, the speed reducer 7 is disposed axially between the first electric motor 2 and the torque converter 3. The speed reducer 7 transmits the torque from the torque converter 3 to the drive wheel 101 side. Specifically, the speed reducer 7 amplifies the torque from the torque converter 3 and transmits it to the drive wheel 101 side via the differential gear 109. Note that the speed reducer 7 has a plurality of gears 71. The speed reducer 7 is housed in the transmission case 72. Note that one of the plurality of gears 71 is fixed to the output shaft 6. The gear 71 rotates integrally with the output shaft 6.

[0058] <Torque converter case 8> The torque converter case 8 houses the torque converter 3. The torque converter case 8 may be formed of one member together with the transmission case 72, or may be formed of separate members. The torque converter case 8 and the outer shell of the torque converter 3 are arranged at a distance from each other. For this reason, an air layer is formed between the torque converter case 8 and the outer shell of the torque converter 3.

[0059] <Differential gear> The drive unit 100 further includes a differential gear 109 and a pair of drive shafts 110. The differential gear 109 is configured to transmit the torque from the speed reducer 7 to the pair of drive wheels 101.

[0060] The pair of drive shafts 110 extends from the differential gear 109 to the pair of drive wheels 101. The drive shaft 110 extends parallel to the input shaft 5. Further, the drive shaft 110 extends offset with respect to the input shaft 5.

[0061] The differential gear 109 is disposed at the center between the pair of drive wheels 101 in the direction in which the drive shafts 110 extend. That is, the pair of drive shafts 110 are substantially the same length as each other.

[0062] <Pump 11> The pump 11 is configured to supply the working fluid into the torque converter 3. The working fluid supplied by the pump 11 is supplied into the torque converter 3 through, for example, a flow path between the fixed shaft 104 and the second boss portion 323a, or a flow path between the fixed shaft 104 and the output shaft 6.

[0063] The pump 11 is driven by the second electric motor 12. Note that the pump 11 is not driven by the first electric motor 2. In this embodiment, the drive unit 100 has only one pump 11 for supplying the working fluid into the torque converter 3.

[0064] <The second electric motor 12> The second electric motor 12 is configured to drive the pump 11. The second electric motor 12 is a motor dedicated to the pump 11. This second electric motor 12 is not used for driving the drive wheels 101.

[0065] <The tank 13> The tank 13 stores the working fluid to be supplied to the torque converter 3. The tank 13 is connected to the torque converter 3 via the circulation circuit 4.

[0066] <Various sensors> The drive unit 100 further includes a first rotation sensor 14a, a second rotation sensor 14b, a temperature sensor 14c, and a working fluid amount sensor 14d. The first rotation sensor 14a is configured to detect the rotational speed of the impeller 32. The second rotation sensor 14b is configured to detect the rotational speed of the turbine 33.

[0067] The temperature sensor 14c is configured to detect the temperature of the working fluid in the torque converter 3. The working fluid amount sensor 14d is configured to detect the amount of the working fluid in the tank 13.

[0068] <The control unit 15> The control unit 15 is configured to control the second electric motor 12. That is, the control unit 15 is configured to control the operation of the pump 11 by controlling the second electric motor 12. The control unit 15 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), etc. The control unit 15 is, for example, a microcomputer.

[0069] Specifically, the control unit 15 controls the second electric motor 12 based on the amount of working fluid in the torque converter 3, the input / output rotation ratio of the torque converter 3, the temperature of the working fluid in the torque converter 3, and the rotation direction of the first electric motor 2.

[0070] The control unit 15 obtains information regarding the amount of working fluid in the tank 13 from the working fluid amount sensor 14d. Then, the control unit 15 controls the second electric motor 12 based on this information regarding the amount of working fluid in the tank 13. Specifically, the control unit 15 estimates the amount of working fluid in the torque converter 3 from the information regarding the amount of working fluid in the tank 13.

[0071] Then, the control unit 15 determines whether or not the amount of working fluid in the tank 13 is equal to or greater than a first threshold value. When the amount of working fluid in the tank 13 is equal to or greater than the first threshold value, since the amount of working fluid in the torque converter 3 is less than the desired amount, the control unit 15 turns on the second electric motor 12. As a result, the pump 11 is driven and the working fluid is supplied into the torque converter 3.

[0072] Note that when the amount of working fluid in the tank 13 is less than the first threshold value, it means that the working fluid is sufficiently supplied into the torque converter 3 and the amount of working fluid in the torque converter 3 is equal to or greater than the desired amount. As described above, the control unit 15 indirectly determines the amount of working fluid in the torque converter 3 and controls the second electric motor 12 based on the amount of working fluid in the torque converter 3.

[0073] The input / output rotation ratio (N2 / N1) of the torque converter 3 can be represented by the ratio (N2 / N1) of the rotational speed N2 of the turbine 33 to the rotational speed N1 of the impeller 32. The control unit 15 acquires information regarding the rotational speed N1 of the impeller 32 detected by the first rotation sensor 14a. Further, the control unit 15 acquires information regarding the rotational speed N2 of the turbine 33 detected by the second rotation sensor 14b. Then, the control unit 15 calculates the input / output rotation ratio (N2 / N1) of the torque converter 3 based on the information regarding the rotational speed N1 of the impeller 32 and the information regarding the rotational speed N2 of the turbine 33.

[0074] The control unit 15 controls the second electric motor 12 based on the input / output rotation ratio (N2 / N1) of this torque converter 3. For example, the control unit 15 determines whether or not the input / output rotation ratio (N2 / N1) of the torque converter 3 is equal to or less than a second threshold value. When the input / output rotation ratio (N2 / N1) of the torque converter 3 is equal to or less than the second threshold value, the working fluid in the torque converter 3 becomes high temperature due to shear heat. For this reason, the control unit 15 turns on the second electric motor 12. Thereby, the pump 11 is driven and the working fluid is supplied into the torque converter 3. As a result, the working fluid that has become high temperature in the torque converter 3 can be sent to the outside of the torque converter 3, and it is possible to suppress the inside of the torque converter 3 from becoming high temperature.

[0075] The control unit 15 acquires information regarding the temperature of the working fluid in the torque converter 3 from the temperature sensor 14c. Then, the control unit 15 controls the second electric motor 12 based on the information regarding the temperature of the working fluid in this torque converter 3.

[0076] The control unit 15 determines whether or not the temperature of the working fluid in the torque converter 3 is equal to or higher than a third threshold value. When the temperature of the working fluid in the torque converter 3 is equal to or higher than the third threshold value, the control unit 15 turns on the second electric motor 12.

[0077] The control unit 15 acquires information regarding the rotational direction of the first electric motor 2. For example, the control unit 15 acquires information on whether the first electric motor 2 is rotating forward, rotating backward, or stopped. When the first electric motor 2 is rotating backward, since it is not necessary to supply the working fluid into the torque converter 3, the control unit 15 turns off the second electric motor 12.

[0078] <Control method of drive unit 100> FIG. 3 is a flowchart showing an example of the control method by the control unit 15. As shown in FIG. 3, the control unit 15 first determines whether the operation switch has been turned on (step S1). When the operation switch is turned on, the drive unit 100 is turned on.

[0079] When the control unit 15 determines that the operation switch is not in the on state (No in step S1), that is, when the operation switch is in the off state, it turns off the second electric motor 12 (step S7). As a result, the pump 11 stops.

[0080] When the control unit 15 determines that the operation switch is in the on state (Yes in step S1), next, it determines whether the rotational direction of the first electric motor 2 is reverse rotation (step S2). When the control unit 15 determines that the rotational direction of the first electric motor 2 is reverse rotation (Yes in step S2), it turns off the second electric motor 12 (step S7).

[0081] When the control unit 15 determines that the rotational direction of the first electric motor 2 is not reverse rotation (No in step S2), that is, when the first electric motor 2 is rotating forward or stopped, next, it determines whether the amount of the working fluid in the tank 13 is equal to or more than the first threshold value (step S3). By determining whether the amount of the working fluid in the tank 13 is equal to or more than the first threshold value, the control unit 15 indirectly determines the amount of the working fluid in the torque converter 3.

[0082] When the control unit 15 determines that the amount of the working fluid in the tank 13 is equal to or greater than the first threshold value (Yes in step S3), it turns on the second electric motor 12 to drive the pump 11 (step S6).

[0083] When the control unit 15 determines that the amount of the working fluid in the tank 13 is less than the first threshold value (No in step S3), it then determines whether the input / output rotation ratio (N2 / N1) is equal to or less than the second threshold value (step S4).

[0084] When the control unit 15 determines that the input / output rotation ratio (N2 / N1) is equal to or less than the second threshold value (Yes in step S4), it turns on the second electric motor 12 to drive the pump 11 (step S6).

[0085] When the control unit 15 determines that the input / output rotation ratio (N2 / N1) is greater than the second threshold value (No in step S4), it then determines whether the temperature of the working fluid in the torque converter 3 is equal to or higher than the third threshold value (step S5).

[0086] When the control unit 15 determines that the temperature of the working fluid in the torque converter 3 is equal to or higher than the third threshold value (Yes in step S5), it turns on the second electric motor 12 to drive the pump 11 (step S6).

[0087] When the control unit 15 determines that the temperature of the working fluid in the torque converter 3 is less than the third threshold value (No in step S5), it turns off the second electric motor 12 to stop the pump 11 (step S7).

[0088] [Modification Example] Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications are possible without departing from the spirit of the present invention.

[0089] Modification Example 1 As shown in FIG. 4, the drive unit 100 may further include a battery temperature adjustment circuit 16, a working fluid cooler 17, a first flow path 18a, a second flow path 18b, and a switching valve 19. The battery temperature adjustment circuit 16 is configured to adjust the temperature of the battery by the working fluid. Specifically, the battery temperature adjustment circuit 16 is configured to cool the battery by the working fluid so that the temperature of the battery does not become too high.

[0090] The working fluid cooler 17 is configured to cool the working fluid. The first flow path 18a is configured to supply the working fluid to the battery temperature adjustment circuit 16 via the working fluid cooler 17. The second flow path 18b is configured to supply the working fluid to the battery temperature adjustment circuit 16 without passing through the working fluid cooler 17. The first flow path 18a and the second flow path 18b are connected in parallel to each other.

[0091] The switching valve 19 is configured to switch the flow path through which the working fluid is supplied. Specifically, the switching valve 19 switches the flow path through which the working fluid flows between the first flow path 18a and the second flow path 18b.

[0092] The control unit 15 acquires information regarding the outside air temperature. Then, the control unit 15 controls the switching valve 19 based on the acquired information on the outside air temperature. For example, when it is determined that the outside air temperature is equal to or higher than a fourth threshold value, the control unit 15 controls the switching valve 19 so that the working fluid flows through the first flow path 18a. Also, when it is determined that the outside air temperature is lower than the fourth threshold value, the control unit 15 controls the switching valve 19 so that the working fluid flows through the second flow path 18b.

[0093] Modification Example 2 In the above embodiment, the control unit 15 controls the second electric motor 12 based on all of the input / output rotation ratio (N2 / N1), the working fluid temperature, and the amount of the working fluid, but the configuration of the control unit 15 is not limited thereto. For example, the control unit 15 may control the second electric motor 12 based on any one of the input / output rotation ratio (N2 / N1), the working fluid temperature, and the amount of the working fluid, or may control the second electric motor 12 based on any two of them.

[0094] Modification Example 3 In the above embodiment, the control unit 15 indirectly detected the amount of the working fluid in the torque converter 3 by detecting the amount of the working fluid in the tank 13. However, the configuration of the control unit 15 is not limited to this. For example, the control unit 15 may directly detect the amount of the working fluid in the torque converter 3 instead of detecting the amount of the working fluid in the tank 13.

[0095] Modification Example 4 In the above embodiment, the torque converter 3 had a centrifugal lock-up clutch 37. However, the configuration of the torque converter 3 is not limited to this. For example, the torque converter 3 may have a lock-up piston that operates by the pressure of the working fluid. The lock-up piston receives the pressure of the working fluid from the pump 11 and moves axially to frictionally engage with the cover 31.

Explanation of Reference Numerals

[0096] 2: First electric motor 3: Torque converter 11: Pump 12: Second electric motor 13: Tank 15: Control unit 16: Battery temperature adjustment circuit 17: Working fluid cooler 18a: First flow path 18b: Second flow path 19: Switching valve 100: Drive unit 101: Driving wheel

Claims

1. A first electric motor configured to drive a drive wheel; A fluid coupling configured to receive torque from the first electric motor; A pump configured to supply a working fluid into the fluid coupling; A second electric motor configured to drive the pump; A control unit configured to control the second electric motor based on at least one of an input / output rotation ratio of the fluid coupling, a temperature of the working fluid in the fluid coupling, and an amount of the working fluid in the fluid coupling; Comprising; The control unit controls the second electric motor based on a rotation direction of the first electric motor. A drive unit.

2. Further comprising a tank for storing the working fluid supplied to the fluid coupling, The control unit determines the amount of the working fluid in the fluid coupling based on the amount of the working fluid in the tank. The drive unit according to Claim 1.

3. A battery temperature adjustment circuit configured to adjust the temperature of a battery by a working fluid; A working fluid cooler configured to cool the working fluid; A first flow path configured to supply the working fluid to the battery temperature adjustment circuit via the working fluid cooler; A second flow path configured to supply the working fluid to the battery temperature adjustment circuit without passing through the working fluid cooler; A switching valve configured to switch a flow path for supplying the working fluid between the first flow path and the second flow path; Further comprising the drive unit according to Claim 1 or 2.

4. The control unit controls the switching valve based on an outside air temperature. The drive unit according to Claim 3.

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