Drive unit

Abstract

To efficiently recover regenerative energy.SOLUTION: A drive unit 100 includes a first electric motor 2a, a second electric motor 2b, and a fluid coupling 5. The fluid coupling 5 has an input part and an output part. In the input part, torque is transmitted from the first electric motor 2a. In the output part, torque is transmitted from the input part through fluid. The second electric motor 2b is connected to the output part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] An electric vehicle runs using an electric motor as a drive source. The electric motor functions as a drive source when the vehicle is running, and can also function as a generator when decelerating. When the electric motor functions as a generator, regenerative energy generated by the electric motor is stored in a battery (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-146788 Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric vehicle configured as described above, there is a demand for efficient recovery of regenerative energy. Therefore, an object of the present invention is to provide a drive unit that can efficiently recover regenerative energy. [Means for solving the problem]

[0005] A drive unit according to one aspect of the present invention includes a first electric motor, a second electric motor, and a fluid coupling. The fluid coupling has an input section and an output section. The input section is configured to receive torque from the first electric motor. The output section is configured to receive torque from the input section via a fluid. The second electric motor is connected to the output section.

[0006] According to this configuration, the drive unit has a second electric motor in addition to the first electric motor. Because the second electric motor is connected to the output of the fluid coupling, the second electric motor can recover regenerative energy without using a fluid. In other words, by using the second electric motor, regenerative energy can be recovered efficiently.

[0007] Preferably, the drive unit further includes a first power storage device and a second power storage device. The first power storage device is electrically connected to the first electric motor. The second power storage device is electrically connected to the second electric motor. In this way, the drive unit includes a power storage device for each electric motor.

[0008] Preferably, the second power storage device is a capacitor.

[0009] Preferably, the drive unit further includes a control unit that controls the first electric motor and the second electric motor.

[0010] Preferably, the control unit performs regenerative braking by the second electric motor with priority over regenerative braking by the first electric motor.

[0011] Preferably, when the control unit determines that the remaining amount of power of the second power storage device is less than the first threshold value during deceleration, the control unit causes the second electric motor to perform regenerative braking.

[0012] Preferably, the control unit gives priority to running the vehicle using the second electric motor over running the vehicle using the first electric motor.

[0013] Preferably, when the control unit determines that the remaining amount of power in the second power storage device is equal to or greater than the second threshold value during running, the control unit causes the vehicle to run using the second electric motor.

[0014] Preferably, the control unit operates the second electric motor when the vehicle is reversing.

[0015] Preferably, the second electric motor is disposed between the first electric motor and the fluid coupling.

[0016] Preferably, the first electric motor has a first stator and a first rotor, and the second electric motor has a second stator and a second rotor. The second rotor has a smaller inertia than the first rotor. Therefore, the second electric motor has better responsiveness than the first electric motor. [Effects of the Invention]

[0017] According to the present invention, regenerative energy can be efficiently recovered. [Brief explanation of the drawings]

[0018] [Figure 1] Schematic diagram of a drive unit. [Figure 2] FIG. [Figure 3] Enlarged view of the first switching mechanism and its surroundings. [Figure 4] Enlarged view of the first switching mechanism and its surroundings. [Figure 5] Enlarged view of the first switching mechanism and its surroundings. [Figure 6] 4 is a flowchart showing the operation of a control unit. [Figure 7] 4 is a flowchart showing the operation of a control unit. DETAILED DESCRIPTION OF THE INVENTION

[0019] The drive unit according to this embodiment will be described below with reference to the drawings. Fig. 1 is a schematic diagram of the drive unit. In the following description, the axial direction refers to the direction in which the rotation axis O of the first electric motor 2a and the torque converter 5 extends. The radial direction refers to the radial direction of a circle centered on the rotation axis O.

[0020] <Output unit> 1, the drive unit 100 is configured to drive an output unit 101. The output unit 101 includes a final gear train 102, a differential gear 103, a pair of drive shafts 105, and drive wheels 110. Note that the output unit 101 may include only the drive wheels 110.

[0021] A pair of drive shafts 105 extend from the differential gear 103 to a pair of drive wheels 110. The drive shafts 105 extend parallel to the rotation axis O. More specifically, the drive shafts 105 extend parallel to the first and second torque transmission shafts 6a and 6b, which will be described later. The drive shafts 105 also extend offset relative to the first and second torque transmission shafts 6a and 6b.

[0022] The differential gear 103 is disposed in the center between the pair of drive wheels 110 in the direction in which the drive shafts 105 extend. That is, the pair of drive shafts 105 have substantially the same length.

[0023] <Drive unit> The drive unit 100 includes first and second electric motors 2a, 2b, first and second power storage devices 3a, 3b, first and second inverters 4a, 4b, a torque converter 5 (an example of a fluid coupling), first and second torque transmission shafts 6a, 6b, a torque output unit 7, a switching mechanism 8, and a control unit 9. The drive unit 100 is mounted on, for example, an electric vehicle. Note that in this embodiment, the drive unit 100 does not include an engine, but may include an engine.

[0024] <First and second electric motors> The first electric motor 2a and the second electric motor 2b are arranged at a distance from each other in the axial direction. A torque output unit 7 is disposed between the first electric motor 2a and the second electric motor 2b. The first electric motor 2a, the torque output unit 7, and the second electric motor 2b are arranged in this order in the axial direction. The rotation shaft of the first electric motor 2a is arranged coaxially with the rotation shaft of the second electric motor 2b.

[0025] The first electric motor 2a has a first motor case 21a, a first stator 22a, and a first rotor 23a. The second electric motor 2b has a second motor case 21b, a second stator 22b, and a second rotor 23b.

[0026] In this embodiment, the first and second electric motors 2a and 2b are so-called inner rotor motors. The first and second electric motors 2a and 2b are configured to be rotatable in a first rotation direction and a second rotation direction. The second rotation direction is opposite to the first rotation direction.

[0027] The second electric motor 2b is smaller than the first electric motor 2a. That is, the second electric motor 2b is smaller in size than the first electric motor 2a. For example, the second electric motor 2b has a smaller axial size than the first electric motor 2a. Furthermore, the second electric motor 2b may have a smaller radial size than the first electric motor 2a.

[0028] The second rotor 23b of the second electric motor 2b has a smaller inertia than the first rotor 23a of the first electric motor 2a. For example, the second rotor 23b has a smaller mass than the first rotor 23a.

[0029] The first and second motor cases 21a, 21b are fixed to the vehicle body frame or the like and are non-rotatable. The first and second stators 22a, 22b are fixed to the inner circumferential surfaces of the first and second motor cases 21a, 21b, respectively. The first and second stators 22a, 22b are non-rotatable. The first and second rotors 23a, 23b rotate around a rotation axis O. The first and second rotors 23a, 23b are disposed radially inside the first and second stators 22a, 22b.

[0030] The first and second electric motors 2a, 2b are configured to function as a drive source and also as a generator.

[0031] <First and second power storage devices> The first power storage device 3a is electrically connected to the first electric motor 2a. More specifically, the first power storage device 3a is electrically connected to the first electric motor 2a via a first inverter 4a. The first power storage device 3a is configured to exchange electric power with the first electric motor 2a. The first power storage device 3a is, for example, a battery. More specifically, the first power storage device 3a is a lithium-ion battery.

[0032] The first power storage device 3a supplies electric power to the first electric motor 2a when the first electric motor 2a functions as a drive source, and stores the electric power generated by the first electric motor 2a when the first electric motor 2a functions as a generator.

[0033] The second power storage device 3b is electrically connected to the second electric motor 2b. More specifically, the second power storage device 3b is electrically connected to the second electric motor 2b via a second inverter 4b. The second power storage device 3b is configured to exchange electric power with the second electric motor 2b. The second power storage device 3b is, for example, a capacitor. More specifically, the second power storage device 3b is an electric double layer capacitor.

[0034] The second power storage device 3b, which is a capacitor, can store the electric power obtained by regenerative braking more efficiently than the first power storage device 3a, which is a battery.

[0035] The second power storage device 3b supplies electric power to the second electric motor 2b when the second electric motor 2b functions as a drive source, and stores the electric power generated by the second electric motor 2b when the second electric motor 2b functions as a generator.

[0036] <First and second inverters> The first inverter 4a is electrically connected to the first electric motor 2a. The first inverter 4a is also electrically connected to the first power storage device 3a. Specifically, the first inverter 4a is disposed between the first electric motor 2a and the first power storage device 3a.

[0037] The first inverter 4a is configured to control the voltage, frequency, and phase of the electric power supplied from the first power storage device 3a to the first electric motor 2a, and to adjust the rotation speed and output torque of the first electric motor 2a.

[0038] The second inverter 4b is electrically connected to the second electric motor 2b. The second inverter 4b is also electrically connected to the second power storage device 3b. Specifically, the second inverter 4b is disposed between the second electric motor 2b and the second power storage device 3b.

[0039] The second inverter 4b is configured to control the voltage, frequency, and phase of the electric power supplied from the second power storage device 3b to the second electric motor 2b, and to adjust the rotation speed and output torque of the second electric motor 2b.

[0040] <Torque converter> The torque converter 5 is disposed axially apart from the first electric motor 2a. The second electric motor 2b is disposed between the torque converter 5 and the first electric motor 2a. The first electric motor 2a, the second electric motor 2b, and the torque converter 5 are arranged in this order in the axial direction.

[0041] The rotation axis O of the torque converter 5 is arranged coaxially with the rotation axis O of the first electric motor 2a. Torque is transmitted to the torque converter 5 from the first electric motor 2a. The torque converter 5 is configured to amplify the torque in the first rotation direction output by the first electric motor 2a. However, the torque converter 5 does not amplify the torque in the second rotation direction output by the first electric motor 2a. The torque converter 5 outputs the amplified torque to the torque output unit 7.

[0042] As shown in Fig. 2, the torque converter 5 has a cover 51, an impeller 52, a turbine 53, and a stator 54. The torque converter 5 also has a centrifugal lock-up clutch 55. The cover 51 and the impeller 52 correspond to the input portion of the present invention, and the turbine 53 corresponds to the output portion of the present invention. Hereinafter, the cover 51 and the impeller 52 may be collectively referred to as the input portion of the torque converter 5. The turbine 53 may also be referred to as the output portion of the torque converter 5.

[0043] The torque converter 5 is disposed so that the impeller 52 faces the first electric motor 2a (left side in FIG. 1) and the cover 51 faces the opposite side to the first electric motor 2a (right side in FIG. 1). The torque converter 5 is housed in a torque converter case 50. A working fluid is supplied to the torque converter 5. The working fluid is, for example, hydraulic oil.

[0044] The torque output by the first electric motor 2a is input to the cover 51. That is, torque is transmitted from the first electric motor 2a to the input portion of the torque converter 5. The cover 51 is rotated by the torque from the first electric motor 2a. The cover 51 is fixed to the first torque transmission shaft 6a. For example, the cover 51 has a spline hole, and the first torque transmission shaft 6a is spline-fitted into the spline hole of the cover 51. Therefore, the cover 51 rotates integrally with the first torque transmission shaft 6a. The cover 51 is arranged to cover the turbine 53.

[0045] The cover 51 has a disk portion 511, a cylindrical portion 512, and a cover hub 513. The disk portion 511 has an opening in the center. The cylindrical portion 512 extends from the outer peripheral end of the disk portion 511 toward the first electric motor 2a. The disk portion 511 and the cylindrical portion 512 are formed from a single member.

[0046] The cover hub 513 is fixed to the inner peripheral end of the disc portion 511. In this embodiment, the cover hub 513 is formed as a separate member from the disc portion 511, but the cover hub 513 and the disc portion 511 may be formed as a single member.

[0047] The cover hub 513 has a spline hole into which the first torque transmission shaft 6a is spline-fitted. The cover hub 513 is rotatably supported by the torque converter case 50 via a bearing member (not shown).

[0048] The impeller 52 rotates integrally with the cover 51. The impeller 52 is fixed to the cover 51. The impeller 52 has an impeller shell 521, a plurality of impeller blades 522, and an impeller hub 523.

[0049] The impeller shell 521 is fixed to the cover 51. A plurality of impeller blades 522 are attached to the inner surface of the impeller shell 521.

[0050] The impeller hub 523 is attached to the inner peripheral end of the impeller shell 521. In this embodiment, the impeller hub 523 is configured as a single member together with the impeller shell 521, but the impeller hub 523 may be configured as a separate member from the impeller shell 521.

[0051] The turbine 53 is disposed opposite the impeller 52. More specifically, the turbine 53 faces the impeller 52 in the axial direction. Torque from the impeller 52 is transmitted to the turbine 53 via the working fluid. That is, torque is transmitted to the output portion of the torque converter 5 from the input portion via the working fluid.

[0052] The turbine 53 is connected to the second electric motor 2b. More specifically, the turbine 53 is connected to the second electric motor 2b via a second torque transmission shaft 6b. Therefore, the turbine 53 rotates integrally with the second rotor 23b of the second electric motor 2b.

[0053] The turbine 53 includes a turbine shell 531, a plurality of turbine blades 532, and a turbine hub 533. The turbine blades 532 are fixed to the inner surface of the turbine shell 531.

[0054] The turbine hub 533 is fixed to the inner peripheral end of the turbine shell 531. For example, the turbine hub 533 is fixed to the turbine shell 531 by rivets. In this embodiment, the turbine hub 533 is formed as a separate member from the turbine shell 531, but the turbine hub 533 and the turbine shell 531 may be formed as a single member.

[0055] The second torque transmission shaft 6b is attached to the turbine hub 533. More specifically, the second torque transmission shaft 6b is spline-fitted to the turbine hub 533. The turbine hub 533 rotates integrally with the second torque transmission shaft 6b. That is, the torque converter 5 outputs the amplified torque to the second torque transmission shaft 6b.

[0056] The stator 54 is configured to rectify the flow of hydraulic oil returning from the turbine 53 to the impeller 52. The stator 54 is rotatable around a rotation axis O. For example, the stator 54 is supported on a fixed shaft 104 via a one-way clutch 56. The stator 54 is disposed between the impeller 52 and the turbine 53 in the axial direction.

[0057] The fixed shaft 104 extends axially within the impeller hub 523. The fixed shaft 104 is cylindrical, and the second torque transmission shaft 6b extends axially within the fixed shaft 104. The fixed shaft 104 extends, for example, from the transmission case 70 or the torque converter case 50. The fixed shaft 104 is non-rotatable.

[0058] The stator 54 has a disk-shaped stator carrier 541 and a plurality of stator blades 542 attached to the outer circumferential surface thereof.

[0059] The one-way clutch 56 is disposed between the fixed shaft 104 and the stator 54. The one-way clutch 56 is configured to allow the stator 54 to rotate in a first rotational direction. On the other hand, the one-way clutch 56 prevents the stator 54 from rotating in a second rotational direction. Torque is amplified by the stator 54 and transmitted from the impeller 52 to the turbine 53.

[0060] The centrifugal lock-up clutch 55 is attached to the turbine 53. The lock-up clutch 55 rotates integrally with the turbine 53. The lock-up clutch 55 is configured to connect the cover 51 and the turbine 53 by centrifugal force generated by the rotation of the turbine 53. In detail, the lock-up clutch 55 is configured to transmit torque from the cover 51 to the turbine 53 when the turbine 53 reaches or exceeds a predetermined rotation speed.

[0061] The lock-up clutch 55 has a plurality of centrifugal elements 551 and friction materials 552. The friction materials 552 are attached to the outer peripheral surface of the centrifugal elements 551. The centrifugal elements 551 are arranged so as to be movable in the radial direction. The centrifugal elements 551 are arranged so as not to be movable in the circumferential direction. Therefore, the centrifugal elements 551 rotate together with the turbine 53 and move radially outward due to centrifugal force.

[0062] When the rotation speed of the turbine 53 reaches or exceeds a predetermined rotation speed, the centrifugal element 551 of the lock-up clutch 55 moves radially outward, and the friction material 552 frictionally engages with the inner circumferential surface of the cylindrical portion 512 of the cover 51. As a result, the lock-up clutch 55 is turned on, and torque from the cover 51 is transmitted to the turbine 53 via the lock-up clutch 55. Note that even when the lock-up clutch 55 is turned on, the working fluid can still flow through the lock-up clutch 55.

[0063] When the rotation speed of the turbine 53 falls below a predetermined rotation speed, the centrifugal element 551 moves radially inward, and the frictional engagement between the friction material 552 and the inner circumferential surface of the cylindrical portion 512 of the cover 51 is released. As a result, the lock-up clutch 55 is turned off, and the torque from the cover 51 is not transmitted to the turbine 53 via the lock-up clutch 55. In other words, the torque from the cover 51 is transmitted to the impeller 52, and then transmitted to the turbine 53 via the working fluid.

[0064] <First torque transmission shaft> 1 and 2, the first torque transmission shaft 6a extends from the first electric motor 2a. Specifically, the first torque transmission shaft 6a extends from the first rotor 23a of the first electric motor 2a. The first torque transmission shaft 6a extends toward the torque converter 5. The rotation axis of the first torque transmission shaft 6a is substantially collinear with the rotation axis of the first electric motor 2a and the rotation axis of the torque converter 5.

[0065] The first torque transmission shaft 6a transmits the torque output by the first electric motor 2a to the torque converter 5. The tip end of the first torque transmission shaft 6a is attached to the cover hub 513 of the torque converter 5. The first torque transmission shaft 6a rotates integrally with the rotor 23 of the first electric motor 2a. The first torque transmission shaft 6a extends within the second torque transmission shaft 6b. The first torque transmission shaft 6a is solid.

[0066] <Second torque transmission shaft> The second torque transmission shaft 6b receives torque from the torque converter 5. The second torque transmission shaft 6b outputs the torque from the torque converter 5 to the torque output section 7. The second torque transmission shaft 6b extends in the axial direction from the torque converter 5 toward the first electric motor 2a.

[0067] The second torque transmission shaft 6b is cylindrical. The first torque transmission shaft 6a extends through the second torque transmission shaft 6b. One end (the right end in FIG. 2) of the second torque transmission shaft 6b is attached to the turbine 53 of the torque converter 5. Meanwhile, the other end of the second torque transmission shaft 6b is rotatably supported by, for example, the transmission case 70 via a bearing member or the like.

[0068] The second torque transmission shaft 6b passes through the second electric motor 2b. The second electric motor 2b is attached to the second torque transmission shaft 6b. More specifically, the second rotor 23b of the second electric motor 2b is attached to the second torque transmission shaft 6b. Therefore, the second torque transmission shaft 6b rotates integrally with the second rotor 23b of the second electric motor 2b.

[0069] <Torque output section> 1, the torque output unit 7 is disposed axially between the first electric motor 2a and the second electric motor 2b. The torque output unit 7 is housed in a transmission case 70. In the torque transmission path, the torque output unit 7 is disposed downstream of the second torque transmission shaft 6b.

[0070] The torque output unit 7 outputs the torque from the second torque transmission shaft 6b to the output unit 101. More specifically, the torque output unit 7 outputs the torque to the drive wheels 110 via the differential gear 103. As will be described later, the torque output unit 7 does not output torque in the neutral mode.

[0071] 3, the torque output unit 7 has a first gear train 71 and a second gear train 72. The torque output unit 7 outputs torque from either the first gear train 71 or the second gear train 72.

[0072] The first gear train 71 is configured to output the torque in the first rotational direction output by the first or second electric motor 2a, 2b as torque in the forward rotational direction. The first gear train 71 is also configured to output the torque in the second rotational direction output by the second electric motor 2b as torque in the reverse rotational direction. Therefore, when the first or second electric motor 2a, 2b is rotated in the first rotational direction and torque is output to the output unit 101 via the first gear train 71, the vehicle moves forward. When the second electric motor 2b is rotated in the second rotational direction and torque is output to the output unit 101 via the first gear train 71, the vehicle moves backward.

[0073] The second gear train 72 is configured to output the torque in the first rotational direction output by the first or second electric motor 2a, 2b as torque in the reverse rotational direction. The second gear train 72 is also configured to output the torque in the second rotational direction output by the second electric motor 2b as torque in the forward rotational direction. Therefore, when the first or second electric motor 2a, 2b is rotated in the first rotational direction and torque is output to the output unit 101 via the second gear train 72, the vehicle moves backward. When the second electric motor 2b is rotated in the second rotational direction and torque is output to the output unit 101 via the second gear train 72, the vehicle moves forward.

[0074] The first gear train 71 has a first gear 71a and a second gear 71b that mesh with each other. The first gear 71a is supported on the second torque transmission shaft 6b so as to be relatively rotatable. A ring gear 84 of the switching mechanism 8 (described later) meshes with the first torque input gear 82, causing the first gear 71a to rotate integrally with the second torque transmission shaft 6b.

[0075] The second gear 71b is supported by the drive shaft 73. The second gear 71b rotates integrally with the drive shaft 73. The second gear 71b outputs the torque from the first gear 71a to the drive shaft 73.

[0076] The second gear train 72 has a third gear 72a, a fourth gear 72b, and a fifth gear 72c. The second gear train 72 has one more gear than the first gear train 71. The third gear 72a is supported on the second torque transmission shaft 6b so as to be rotatable relative to the second torque transmission shaft 6b. A ring gear 84 of the switching mechanism 8 (described later) meshes with the second torque input gear 83, causing the third gear 72a to rotate integrally with the second torque transmission shaft 6b.

[0077] The fourth gear 72b meshes with the third gear 72a. The fourth gear 72b is supported by a countershaft (not shown). The fourth gear 72b may rotate integrally with the countershaft, or may rotate relative to the countershaft.

[0078] The fifth gear 72c is in mesh with the fourth gear 72b. The fifth gear 72c is supported by the drive shaft 73. The fifth gear 72c rotates integrally with the drive shaft 73. The fifth gear 72c outputs torque from the third gear 72a to the drive shaft 73.

[0079] The gear ratio in the first gear train 71 is different from the gear ratio in the second gear train 72. Specifically, the gear ratio in the second gear train 72 is greater than the gear ratio in the first gear train 71. Note that the gear ratio in the second gear train 72 may be smaller than the gear ratio in the first gear train 71.

[0080] The torque output unit 7 can be in any one of a first output mode, a second output mode, and a neutral mode. In the first output mode, the torque output unit 7 outputs torque via a first gear train 71. In the second output mode, the torque output unit 7 outputs torque via a second gear train 72. In the neutral mode, the torque output unit 7 does not output torque from the torque converter 5.

[0081] <Switching mechanism> The switching mechanism 8 is configured to switch the state of the torque output unit 7 between a first output mode, a second output mode, and a neutral mode.

[0082] The switching mechanism 8 has a torque output gear 81, a first torque input gear 82, a second torque input gear 83, a ring gear 84, and an actuator (not shown). The switching mechanism 8 may also have a lever 85. The actuator is controlled by a control unit 9. The actuator controlled by the control unit 9 moves the ring gear 84 in the axial direction.

[0083] The torque output gear 81 is attached to the second torque transmission shaft 6b. The torque output gear 81 rotates integrally with the second torque transmission shaft 6b. The torque output gear 81 may be formed as a single member together with the second torque transmission shaft 6b, or may be formed as a separate member. The torque output gear 81 has a plurality of teeth on its outer circumferential surface.

[0084] The first torque input gear 82 is supported on the second torque transmission shaft 6b so as to be rotatable relative to the second torque transmission shaft 6b. The first torque input gear 82 rotates integrally with the second torque transmission shaft 6b by meshing with the ring gear 84. The first torque input gear 82 rotates integrally with the first gear 71a of the first gear train 71. The first torque input gear 82 may be formed of a single member together with the first gear 71a, or may be formed of a separate member.

[0085] The second torque input gear 83 is supported on the second torque transmission shaft 6b so as to be rotatable relative to the second torque transmission shaft 6b. The second torque input gear 83 rotates integrally with the second torque transmission shaft 6b by meshing with the ring gear 84. The second torque input gear 83 rotates integrally with the third gear 72a of the second gear train 72. The second torque input gear 83 may be formed of a single member together with the third gear 72a, or may be formed of a separate member.

[0086] The ring gear 84 has a plurality of teeth on its inner peripheral surface. The ring gear 84 is always in mesh with the torque output gear 81 and rotates integrally with the torque output gear 81. In other words, the ring gear 84 rotates integrally with the second torque transmission shaft 6b. The ring gear 84 is arranged so as to be movable in the axial direction.

[0087] The ring gear 84 can be in mesh with the torque output gear 81 and the first torque input gear 82 (see FIG. 3). When the ring gear 84 is in mesh with the torque output gear 81 and the first torque input gear 82 in this way, the torque from the second torque transmission shaft 6b is output via the first gear train 71 (first output mode).

[0088] On the other hand, the ring gear 84 can also be in a state where it meshes with the torque output gear 81 and the second torque input gear 83 (see FIG. 4). When the ring gear 84 meshes with the torque output gear 81 and the second torque input gear 83 in this way, the torque from the second torque transmission shaft 6b is output via the second gear train 72 (second output mode).

[0089] Furthermore, when the switching mechanism 8 is in the neutral position, the ring gear 84 is in mesh with only the torque output gear 81 (see FIG. 5). In this way, the ring gear 84 is in mesh with only the torque output gear 81 and is not in mesh with both the first torque input gear 82 and the second torque input gear 83, thereby making it possible to cut off torque transmission between the drive shaft 73 and the second torque transmission shaft 6b (neutral mode). In other words, when the switching mechanism 8 is in the neutral position, torque transmission between the drive unit 100 and the output unit 101 is cut off.

[0090] The switching mechanism 8 is controlled by the control unit 9. The ring gear 84 moves in the axial direction under the control of the control unit 9. As a result, the ring gear 84 meshes with the torque output gear 81 and the first torque input gear 82, with the torque output gear 81 and the second torque input gear 83, or with only the torque output gear 81. As a result, the switching mechanism 8 can switch the state of the torque output unit 7 between the first output mode, the second output mode, and the neutral mode.

[0091] When the switching mechanism 8 further includes a lever 85, the lever 85 is connected to the ring gear 84. The lever 85 extends from the ring gear 84 to the outside of the transmission case 70. The lever 85 is operated by the driver. Operating the lever 85 also causes the ring gear 84 to move in the axial direction.

[0092] <Control unit> 1, the control unit 9 is configured to control the first electric motor 2a and the second electric motor 2b. Specifically, the control unit 9 controls the first electric motor 2a by controlling the first inverter 4a. The control unit 9 also controls the second electric motor 2b by controlling the second inverter 4b.

[0093] The control unit 9 is configured to control the torque output unit 7. The control unit 9 controls the torque output unit 7 by controlling the switching mechanism 8. The control unit 9 is configured by, for example, a computer (e.g., a microcomputer) including a CPU (Central Processing Unit) and a ROM (Read Only Memory). The ROM stores programs for performing various calculations. The CPU executes the programs stored in the ROM.

[0094] The control unit 9 prioritizes regenerative braking by the second electric motor 2b over regenerative braking by the first electric motor 2a. Specifically, the control unit 9 executes a first regenerative mode and a second regenerative mode during deceleration. In the first regenerative mode, the control unit 9 executes regenerative braking by the first electric motor 2a. On the other hand, in the second regenerative mode, the control unit 9 executes regenerative braking by the second electric motor 2b.

[0095] The control unit 9 executes the second regeneration mode when the second power storage device 3b can store power, whereas the control unit 9 executes the first regeneration mode when the second power storage device 3b cannot store power.

[0096] 6, the control unit 9 acquires power information of the second power storage device 3b during deceleration (step S1). Based on the power information acquired in step S1, the control unit 9 determines whether the remaining amount of power in the second power storage device 3b is less than a first threshold value (step S2).

[0097] If the control unit 9 determines that the remaining power of the second power storage device 3b is not less than the first threshold (No in step S2), it executes the first regeneration mode (step S3). On the other hand, if the control unit 9 determines that the remaining power of the second power storage device 3b is less than the first threshold (Yes in step S2), it executes the second regeneration mode (step S4). Note that the first threshold may be, but is not limited to, 50%, for example.

[0098] The control unit 9 prioritizes running by the second electric motor 2b over running by the first electric motor 2a. Specifically, the control unit 9 executes either a first running mode or a second running mode during running. In the first running mode, the control unit 9 operates the first electric motor 2a to output torque to the output unit 101. On the other hand, in the second running mode, the control unit 9 operates the second electric motor 2b to output torque to the output unit 101. The control unit 9 may also execute a third running mode in which both the first and second electric motors 2a, 2b are operated to output torque to the output unit 101.

[0099] The control unit 9 executes the second traveling mode when the second power storage device 3b has enough electric power remaining for traveling, whereas the control unit 9 executes the first traveling mode when the second power storage device 3b does not have enough electric power remaining for traveling.

[0100] 7, the control unit 9 acquires power information of the second power storage device 3b while the vehicle is traveling (step S11). Based on the power information acquired in step S11, the control unit 9 determines whether the remaining power of the second power storage device 3b is equal to or greater than a second threshold (step S12).

[0101] If the control unit 9 determines that the remaining power of the second power storage device 3b is not equal to or greater than the second threshold (No in step S12), the control unit 9 executes the first traveling mode (step S13). On the other hand, if the control unit 9 determines that the remaining power of the second power storage device 3b is equal to or greater than the second threshold (Yes in step S12), the control unit 9 executes the second traveling mode (step S14). Note that the second threshold is not particularly limited, but may be set to 10%, for example.

[0102] In the first driving mode, the control unit 9 can move the vehicle forward and backward. When moving the vehicle forward in the first driving mode, the control unit 9 controls the first electric motor 2a to rotate in a first rotation direction. The control unit 9 then outputs torque via the first gear train 71. In detail, the control unit 9 controls the switching mechanism 8 to output torque via the first gear train 71. In this way, the drive unit 100 can move the vehicle forward.

[0103] Furthermore, when the vehicle is reversed in the first driving mode, the control unit 9 controls the first electric motor 2a to rotate in a first rotation direction. Then, the control unit 9 outputs torque via the second gear train 72. In detail, the control unit 9 controls the switching mechanism 8 to output torque via the second gear train 72. In this way, the drive unit 100 can reverse the vehicle.

[0104] Furthermore, in the second driving mode, the control unit 9 can move the vehicle forward and backward. When moving the vehicle forward in the second driving mode, the control unit 9 controls the second electric motor 2b to rotate in a first rotation direction. Then, the control unit 9 outputs torque via the first gear train 71. In detail, the control unit 9 controls the switching mechanism 8 to output torque via the first gear train 71. In this way, the drive unit 100 can move the vehicle forward.

[0105] Furthermore, when the vehicle is reversed in the second driving mode, the control unit 9 controls the second electric motor 2b to rotate in the first rotation direction. Then, the control unit 9 outputs torque via the second gear train 72. In detail, the control unit 9 controls the switching mechanism 8 to output torque via the second gear train 72. In this way, the drive unit 100 can reverse the vehicle.

[0106] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention. Note that the following modifications can be simultaneously applied.

[0107] (a) The control unit 9 may execute a third regenerative mode in which regenerative braking is performed by both the first and second electric motors 2 a, 2 b. For example, the third regenerative mode may be executed when the lock-up clutch 55 is in the ON state and the input and output parts of the torque converter 5 are rotating integrally.

[0108] (b) In the above embodiment, the second rotor 23b has a smaller mass than the first rotor 23a, thereby making the second rotor 23b have a smaller inertia than the first rotor 23a, but the configuration of the first and second rotors 23a, 23b is not limited to this. For example, the second rotor 23b can have a smaller inertia than the first rotor 23a by making the outer diameter of the second rotor 23b smaller than the outer diameter of the first rotor 23a.

[0109] (c) In the above embodiment, the torque output portion 7 has the first and second gear trains 71, 72. However, it is also possible for the torque output portion 7 to have only the first gear train 71 and not the second gear train 72. In this case, the drive unit 100 does not have the switching mechanism 8.

[0110] (d) In the above embodiment, the drive unit 100 includes the torque converter 5, but the configuration of the drive unit 100 is not limited to this. For example, the drive unit 100 may include a fluid coupling that does not include a stator, instead of the torque converter 5. [Explanation of symbols]

[0111] 2a: First electric motor 22a: First stator 23a: First rotor 2b: Second electric motor 22b: Second stator 23b: Second rotor 3a: 1st power storage device 3b:Second power storage device 5: Torque converter 9: Control section 100: Drive unit

Claims

1. a first electric motor; an input configured to receive torque from the first electric motor; and a fluid coupling having an output portion configured to transmit torque via a fluid from the fluid coupling; a second electric motor connected to the output; Equipped with the second electric motor is disposed between the first electric motor and the fluid coupling; Drive unit.

2. A first electric motor; an input configured to receive torque from the first electric motor; and a fluid coupling having an output portion configured to transmit torque via a fluid from the fluid coupling; a second electric motor connected to the output; Equipped with the first electric motor has a first stator and a first rotor; the second electric motor has a second stator and a second rotor having a smaller inertia than the first rotor; Drive unit.

3. a first power storage device electrically connected to the first electric motor; a second power storage device electrically connected to the second electric motor; 3. The drive unit according to claim 1 or 2, further comprising:

4. The second power storage device is a capacitor.

4. The drive unit according to claim 3.

5. a control unit for controlling the first electric motor and the second electric motor; A drive unit according to any one of claims 1 to 4.

6. the control unit causes the second electric motor to perform regenerative braking with priority over the first electric motor.

6. A drive unit according to claim 5.

7. When the control unit determines that the remaining amount of power of the second power storage device is less than a first threshold during deceleration, the control unit causes the second electric motor to perform regenerative braking. A drive unit according to claim 6 when dependent on claim 3 or 4.

8. the control unit causes the second electric motor to run with priority over the first electric motor. A drive unit according to any one of claims 5 to 7.

9. When the control unit determines that the remaining amount of power of the second power storage device is equal to or greater than a second threshold during traveling, the control unit causes the vehicle to travel using the second electric motor. A drive unit according to claim 8 when dependent on claim 3 or 4.

10. The control unit operates the second electric motor when the vehicle is reversing. A drive unit according to any one of claims 5 to 9.

11. the second electric motor is disposed between the first electric motor and the fluid coupling; 3. The drive unit according to claim 2.

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