阅读说明：本技术 变矩器 (Torque converter ) 是由 松冈佳宏 于 2020-03-18 设计创作，主要内容包括：本发明公开了有效地传递转矩的变矩器。变矩器(3)具备盖(31)、叶轮(32)、涡轮(33)、定子(34)以及第一单向离合器(35)。盖(31)被输入来自原动机的转矩。叶轮(32)与盖(31)一体地旋转。涡轮(33)与叶轮(32)相对而置。定子(34)配置于叶轮(32)与涡轮(33)之间。第一单向离合器(35)在正转方向上使盖(31)相对于涡轮(33)能够相对旋转。此外,第一单向离合器(35)在反转方向上使盖(31)与涡轮(33)一体地旋转。(A torque converter that efficiently transmits torque is disclosed. The torque converter (3) is provided with a cover (31), an impeller (32), a turbine (33), a stator (34), and a first one-way clutch (35). The cover (31) receives torque from the motor. The impeller (32) rotates integrally with the cover (31). The turbine (33) is disposed opposite to the impeller (32). The stator (34) is disposed between the impeller (32) and the turbine (33). The first one-way clutch (35) enables the cover (31) to rotate relative to the turbine (33) in the normal direction. The first one-way clutch (35) rotates the cover (31) and the turbine (33) in the reverse direction in an integrated manner.)

1. A torque converter is characterized by comprising:

a cover to which torque from the prime mover is input;

an impeller integrally rotated with the cover;

a turbine disposed opposite the impeller;

a stator disposed between the impeller and the turbine; and

and a first one-way clutch configured to allow the cover to rotate relative to the turbine in a forward direction and to rotate integrally with the turbine in a reverse direction.

2. The torque converter of claim 1,

the torque converter is further provided with a second one-way clutch,

the second one-way clutch enables the stator to rotate in the forward rotation direction and disables the stator from rotating in the reverse rotation direction.

3. The torque converter according to claim 1 or 2,

the torque converter further includes an elastic member that transmits torque from the cover to the first one-way clutch in the reverse rotation direction.

4. The torque converter according to claim 1 or 2,

the torque converter further includes an elastic member that transmits torque from the first one-way clutch to the turbine in the reverse rotation direction.

Technical Field

The present invention relates to a torque converter.

Background

The torque converter has a torque amplification effect. For example, a torque converter disclosed in patent document 1 includes a cover, an impeller, a turbine, a stator, and a one-way clutch. When the torque from the motor is input to the cover, the torque is transmitted to the impeller and the turbine and is output. Here, the stator returns the working oil from the turbine to the impeller, so that the torque is amplified. The stator is mounted to the fixed shaft via a one-way clutch.

Disclosure of Invention

In the torque converter configured as described above, it is desirable to efficiently transmit torque. The technical problem of the present invention is to efficiently transmit torque.

A torque converter according to one aspect of the present invention includes a cover, an impeller, a turbine, a stator, and a first one-way clutch. The cover receives torque from the motor. The impeller rotates integrally with the cover. The turbine is disposed opposite the impeller. The stator is arranged between the impeller and the turbine. The first one-way clutch enables the cover to rotate relative to the turbine in the normal direction. Further, the first one-way clutch rotates the cover integrally with the turbine in the reverse direction.

According to this configuration, torque can be transmitted efficiently when the torque transmission device is mounted on a drive source such as a motor capable of reversing. That is, the first one-way clutch enables the cover to rotate relative to the turbine when rotating in the normal direction. That is, the first one-way clutch does not transmit the torque in the normal rotation direction from the cover to the turbine. Therefore, the torque in the normal rotation direction from the cover is transmitted to the cover, the impeller, and the turbine in this order. Note that the torque in the normal rotation direction is a torque in a direction amplified by the action of the stator.

On the other hand, when rotating in the reverse direction, the first one-way clutch rotates the cover integrally with the turbine. That is, the first one-way clutch transmits the torque in the reverse direction from the cover to the turbine. Therefore, the torque from the cover can be output to the turbine without passing through the working fluid. Note that in this reverse rotation direction, the torque converter does not produce a torque amplification effect. Therefore, an unnecessary torque transmission path can be omitted, and torque can be transmitted efficiently.

Preferably, the torque converter is further provided with a second one-way clutch. The second one-way clutch enables the stator to rotate in the forward direction. Further, the second one-way clutch disables the stator from rotating in the reverse direction.

Preferably, the torque converter is further provided with an elastic member. The elastic member transmits torque from the cover to the first one-way clutch in the reverse direction. According to this configuration, the torque from the cover is transmitted to the first one-way clutch and the turbine via the elastic member, and therefore, rapid torque transmission can be alleviated.

Preferably, the torque converter is further provided with an elastic member. The elastic member transmits the torque from the first one-way clutch to the turbine in the reverse direction. According to this configuration, the torque transmitted from the cover to the first one-way clutch via the elastic member is transmitted to the turbine, and therefore, abrupt torque transmission can be alleviated.

According to the present invention, torque can be transmitted efficiently.

Drawings

Fig. 1 is a schematic view of a drive unit.

Fig. 2 is a sectional view of the drive unit.

FIG. 3 is a cross-sectional view of the torque converter.

Fig. 4 is a cross-sectional view of the impeller hub.

Fig. 5 is a cross-sectional view of the impeller hub.

Fig. 6 is a sectional view of a drive unit for illustrating the first cooling flow path.

Fig. 7 is a sectional view of a side wall portion of the cover.

Fig. 8 is a sectional view of a side wall portion of the cover.

Fig. 9 is a schematic diagram of a drive unit according to a modification.

Fig. 10 is a schematic diagram of a first one-way clutch according to a modification.

Fig. 11 is a schematic diagram of a drive unit according to a modification.

Description of the reference numerals

3 … torque converter; 31 … cover; a 32 … impeller; a 33 … turbine; 34 … stator; 35 … first one-way clutch; 36 … second one-way clutch; 38 … resilient member.

Detailed Description

An embodiment of a drive unit having a torque converter according to the present invention will be described below with reference to the drawings. Fig. 1 is a schematic diagram of a drive unit according to the present embodiment, and fig. 2 is a sectional view of the drive unit according to the present embodiment. In the following description, the axial direction refers to a direction in which the rotation axis O of the motor 2 and the torque converter 3 extends. The circumferential direction is a circumferential direction of a circle having the rotation axis O as a center, and the radial direction is a radial direction of a circle having the rotation axis O as a center. The normal rotation refers to rotation when the vehicle advances, and the reverse rotation refers to rotation when the vehicle retreats.

[ drive unit 100]

As shown in fig. 1 and 2, the drive unit 100 includes a motor 2, a torque converter 3, a speed reducer 4 (an example of a power transmission mechanism), an input shaft 5, an output shaft 6, a torque converter case 7, a working fluid reservoir portion 8, and a first cooling flow path 9 a. The drive unit 100 is mounted on, for example, an electric vehicle. The drive unit 100 transmits torque from the prime mover 2 to the drive wheels 101. The torque converter 3, the torque converter case 7, the working fluid reservoir portion 8, and the first cooling flow path 9a are collectively referred to as a torque converter unit.

< Motor 2>

The motor 2 includes a motor case 21, a stator 22, and a rotor 23. The prime mover 2 in the present embodiment is a motor. Specifically, the motor 2 is a so-called inner rotor type motor. The prime mover housing 21 is fixed to a vehicle body frame or the like and is not rotatable.

The stator 22 is fixed to the inner peripheral surface of the prime mover housing 21. The stator 22 cannot rotate. The rotor 23 rotates about the rotation axis O. The rotor 23 is disposed radially inside the stator 22.

< Torque converter 3>

The torque converter 3 is disposed at an interval from the motor 2 in the axial direction. A speed reducer 4 is disposed between the torque converter 3 and the motor 2. The rotation axis O of the torque converter 3 substantially coincides with the rotation axis O of the prime mover 2. The torque converter 3 receives torque from the prime mover 2. The torque converter 3 amplifies the torque from the prime mover 2 and outputs the amplified torque to the reduction gear 4.

As shown in fig. 3, the torque converter 3 includes 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. The torque converter 3 further has a centrifugal clutch 37.

The torque converter 3 is arranged such that the impeller 32 faces the prime mover 2 side (left side in fig. 3) and the cover 31 faces the opposite side of the prime mover 2 (right side in fig. 3). The torque converter 3 is accommodated in a torque converter case 7. The working fluid is supplied into the torque converter 3. The working fluid is, for example, working oil.

The cover 31 receives torque from the prime mover 2. The cover 31 is rotated by the torque from the prime mover 2. The cover 31 is fixed to the input shaft 5 extending from the prime mover 2. For example, the cover 31 has a spline hole, and the input shaft 5 is spline-fitted in the spline hole of the cover 31. Therefore, the cover 31 rotates integrally with the input shaft 5. The cover 31 is configured to cover the turbine 33.

The cover 31 has a circular plate portion 311, a cylindrical portion 312, and a cover hub 313. The circular plate portion 311 has an opening at the center. The cylindrical portion 312 extends from the outer peripheral end of the disc portion 311 toward the motor 2. The disc portion 311 and the cylindrical portion 312 are formed of one member.

The cover boss 313 is fixed to an inner peripheral end portion of the circular plate portion 311. In the present embodiment, the cover hub 313 and the disk portion 311 are formed of different members, but the cover hub 313 and the disk portion 311 may be formed of one member.

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

The first boss portion 313a is cylindrical and has a spline hole. The input shaft 5 is spline-fitted to the first boss portion 313 a. As shown in fig. 2, the first boss portion 313a is rotatably supported by the torque converter housing 7 via the bearing member 102. Therefore, the first boss portion 313a extends in the axial direction from the first flange portion 313b to the side opposite to the motor 2.

As shown in fig. 3, the first flange portion 313b extends radially outward from the first boss portion 313 a. Specifically, the first flange portion 313b extends radially outward from the end of the first boss portion 313a on the motor 2 side. The circular plate portion 311 is fixed to an outer peripheral end portion of the first flange portion 313 b.

The protruding portion 313c extends in the axial direction from the first flange portion 313 b. The protrusion 313c extends toward the prime mover 2. The protruding portion 313c extends from an outer peripheral end portion of the first flange portion 313 b. The protrusion 313c is cylindrical. The protrusion 313c has a plurality of through holes 313 d. The working fluid is discharged from the torque converter 3 through the through hole 313 d.

The impeller 32 rotates integrally with the cover 31. The impeller 32 is fixed to the cover 31. The impeller 32 includes an impeller shell 321, a plurality of impeller blades 322, an impeller hub 323, and a plurality of supply flow paths 324.

The impeller shell 321 is fixed to the cover 31. The plurality of impeller blades 322 are mounted on the inner side surface of the impeller shell 321.

The impeller boss 323 is mounted to an inner circumferential end portion of the impeller shell 321. In the present embodiment, the impeller boss 323 and the impeller shell 321 are formed of one member, but the impeller boss 323 and the impeller shell 321 may be formed of different members.

The impeller hub 323 has a second boss portion 323a and a second flange portion 323 b. The second boss portion 323a is cylindrical and extends in the axial direction. The second boss portion 323a is rotatably supported by the torque converter housing 7 via the bearing member 103 (see fig. 2). The fixed shaft 104 extends axially within the second boss portion 323 a. Note that the stationary shaft 104 is cylindrical, and the output shaft 6 extends axially inside the stationary shaft 104. Further, the fixed shaft 104 extends from, for example, the reducer case 42 or the torque converter case 7. The fixed shaft 104 cannot rotate.

The supply flow passage 324 is formed in the impeller hub 323. Specifically, the supply channel 324 is formed in the second flange 323 b. The supply flow path 324 extends radially outward from the inner circumferential surface of the impeller hub 323. The supply flow path 324 opens in the torus T. Note that the torus T is a space surrounded by the impeller 32 and the turbine 33.

The supply passage 324 is closed in the axial direction. That is, the supply flow path 324 is a through hole extending in the radial direction in the impeller hub 323. As shown in fig. 4, the supply flow paths 324 extend in a radial shape. The supply flow path 324 is inclined radially outward to the opposite side of the normal rotation direction. That is, the supply channel 324 is inclined in the reverse direction (counterclockwise rotation in fig. 4) toward the radial outer side. Note that the supply channel 324 is not limited to a straight line, and for example, as shown in fig. 5, the supply channel 324 may extend in a curved line.

As shown in fig. 3, the turbine 33 is disposed opposite to the impeller 32. In detail, the turbine 33 is axially opposed to the impeller 32. The torque from the impeller 32 is transmitted to the turbine 33 via the working fluid.

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.

The turbine hub 333 is fixed to an inner peripheral end portion of the turbine housing 331. For example, the turbine hub 333 is fixed to the turbine shell 331 by rivets. In the present embodiment, the turbine boss 333 and the turbine shell 331 are formed of different members, but the turbine boss 333 and the turbine shell 331 may be formed of one member.

The output shaft 6 is mounted 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.

The turbine hub 333 has a third boss part 333a and a third flange part 333 b. The third boss part 333a and the third flange part 333b are formed of one member.

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

The third boss part 333a is arranged at a radial distance from the protruding part 313 c. That is, the protruding portion 313c is disposed radially outward of the third boss portion 333 a. The first one-way clutch 35 is disposed between the third sleeve portion 333a and the protruding portion 313 c. Note that, in a state where the first one-way clutch 35 is not present, the outer peripheral surface of the third sleeve portion 333a opposes the inner peripheral surface of the protruding portion 313 c.

A flow path through which the working fluid flows is formed between the tip of the third boss part 333a and the cover hub 313. In the present embodiment, a plurality of notches 333c are formed at the distal end portion of the third boss portion 333 a. The notch 333c extends in the radial direction at the tip end of the third boss 333 a. The working fluid is discharged from the torque converter 3 through the notch portion 333c and the through hole 313 d.

The third flange 333b extends radially outward from the third boss 333 a. Specifically, the third flange part 333b extends radially outward from the end of the third boss part 333a on the motor 2 side. The turbine shell 331 is fixed to an outer peripheral end portion of the third flange portion 333b by rivets or the like.

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

The stator 34 includes a disk-shaped stator holder 341 and a plurality of stator blades 342 attached to the outer circumferential surface thereof.

The first one-way clutch 35 is disposed between the cover 31 and the turbine 33. The first one-way clutch 35 enables the cover 31 to rotate relative to the turbine 33 in the normal direction. That is, the first one-way clutch 35 is configured to rotate the cover 31 and the turbine 33 relative to each other when the motor 2 rotates in the normal direction to advance the vehicle. Therefore, the first one-way clutch 35 does not transmit torque from the cover 31 to the turbine 33 when the vehicle is moving forward.

On the other hand, the first one-way clutch 35 rotates the cover 31 integrally with the turbine 33 in the reverse direction. That is, the first one-way clutch 35 is configured such that the cover 31 and the turbine 33 rotate integrally when the motor 2 is reversed to move the vehicle backward. Therefore, when the vehicle backs up, the first one-way clutch 35 transmits torque from the cover 31 to the turbine 33.

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 enable the stator 34 to rotate in the normal rotation direction. On the other hand, the second one-way clutch 36 prevents the stator 34 from rotating in the reverse direction. The torque is amplified by the stator 34 and transmitted from the impeller 32 to the turbine 33.

Centrifugal clutch 37 is mounted to turbine 33. The centrifugal clutch 37 rotates integrally with the turbine 33. The centrifugal clutch 37 is configured to connect the cover 31 and the turbine 33 by a centrifugal force generated by rotation of the turbine 33. Specifically, the centrifugal clutch 37 is configured to transmit torque from the cover 31 to the turbine 33 when the turbine 33 has a predetermined number of rotations or more.

The centrifugal clutch 37 has a plurality of centrifuges 371 and friction members 372. The friction material 372 is attached to the outer peripheral surface of the centrifuge 371. The centrifuge 371 is configured to be movable in a radial direction. Note that the centrifuge 371 is configured so as not to be movable in the circumferential direction. Therefore, the centrifuge 371 rotates together with the turbine 33 and moves radially outward by centrifugal force.

In the centrifugal clutch 37, when the number of rotations of the turbine 33 is equal to or greater than a predetermined number of rotations, the centrifuge 371 moves radially outward, and the friction material 372 frictionally engages with the inner circumferential surface of the cylindrical portion 312 of the cover 31. As a result, the centrifugal clutch 37 is in the engaged state, and the torque from the cover 31 is transmitted to the turbine 33 via the centrifugal clutch 37. Note that, even when the centrifugal clutch 37 is in the engaged state, the working fluid can flow through the centrifugal clutch 37.

When the number of rotations of the turbine 33 is smaller than the predetermined number of rotations, the centrifuge 371 moves radially inward, and the friction material 372 is disengaged from the inner circumferential surface of the cylindrical portion 312 of the cover 31. As a result, the centrifugal clutch 37 is disengaged, and the torque from the cover 31 is not transmitted to the turbine 33 via the centrifugal clutch 37. That is, after the torque from the cover 31 is transmitted to the impeller 32, the torque is transmitted to the turbine 33 via the working fluid.

< speed reducer 4>

As shown in fig. 2, the speed reducer 4 is disposed between the prime mover 2 and the torque converter 3 in the axial direction. The speed reducer 4 transmits the torque from the torque converter 3 to the drive wheels 101. Specifically, the speed reducer 4 amplifies the torque from the torque converter 3 and transmits the amplified torque to the driving wheels 101 via the differential gear 109. Note that the speed reducer 4 has a plurality of gears 41 and a speed reducer case 42 that accommodates each gear 41. Note that one of the plurality of gears 41 is fixed to the output shaft 6. In the present embodiment, the gear 41 and the output shaft 6 are formed of one member.

< input shaft 5>

The input shaft 5 extends from the prime mover 2. The input shaft 5 extends toward the torque converter 3. The rotation axis of the input shaft 5 is substantially on the same line as the rotation axis of the motor 2 and the rotation axis of the torque converter 3.

The input shaft 5 inputs the torque from the prime mover 2 to the torque converter 3. The front end portion of the input shaft 5 is attached to a cover hub 313 of the torque converter 3. The input shaft 5 rotates integrally with the rotor 23 of the prime mover 2. The input shaft 5 extends within the output shaft 6. The input shaft 5 is solid. The input shaft 5 has a communication passage 51 at a distal end portion. The communication passage 51 extends in the axial direction. Further, the communication passage 51 opens to the first cooling passage 9 a.

< output shaft 6>

The output shaft 6 outputs torque from the torque converter 3. The output shaft 6 outputs the torque from the torque converter 3 to the reduction gear 4. The output shaft 6 extends from the torque converter 3 toward the prime mover 2.

The output shaft 6 is cylindrical. The input shaft 5 extends within the output shaft 6. One end portion (right end portion in fig. 2) of the output shaft 6 is attached to the turbine 33 of the torque converter 3. On the other hand, the other end portion (left end portion in fig. 2) of the output shaft 6 is rotatably supported by the reduction gear case 42 via a bearing member 105.

< Torque converter case 7>

As shown in fig. 6, the torque converter housing 7 accommodates the torque converter 3. In the present embodiment, the torque converter housing 7 and the reduction gear housing 42 are formed of one member, but may be formed of different members.

The torque converter housing 7 has a side wall portion 71, an outer wall portion 72, and a plurality of fins 73. The side wall portion 71 is disposed opposite to the cover 31 of the torque converter 3. The side wall portion 71 is disposed orthogonal to the rotation axis O.

The torque converter 3 is disposed on one side (left side in fig. 6) of the side wall portion 71 in the axial direction. On the other hand, the other side (right side surface in fig. 6) of the side wall portion 71 is in contact with the outside air. That is, no member serving as a heat source is disposed on the other side of the side wall portion 71.

The cover 31 is rotatably attached to the center portion of the side wall portion 71 via a bearing member 102. The side wall portion 71 is made of a material having a large specific heat and thermal conductivity so that a large amount of heat can be quickly absorbed from the working fluid flowing through the first cooling flow path 9a and dissipated to the atmosphere. For example, the side wall portion 71 is made of magnesium, aluminum, or the like.

The outer wall portion 72 is disposed to face the outer peripheral surface of the torque converter 3. The outer wall portion 72 and the side wall portion 71 are formed of one member, but may be formed of different members. The outer wall portion 72 extends from the outer peripheral end portion of the side wall portion 71 toward the prime mover 2. The outer wall portion 72 extends substantially parallel to the rotation axis O. Note that the tip end portion (the end portion on the prime mover 2 side) of the outer wall portion 72 is inclined radially inward. The material of the outer wall portion 72 may be the same as that of the side wall portion 71.

The heat sink 73 is formed on the side wall portion 71. The heat sink 73 extends from the side wall portion 71 to the side opposite to the torque converter 3 (the right side in fig. 6). The fins 73 are attached to the side wall portion 71 in order to efficiently dissipate heat from the working fluid flowing through the first cooling channel 9 a. The thermal conductivity of the heat sink 73 is preferably the same as or higher than that of the side wall portion 71, but is not particularly limited. The heat sink 73 is made of, for example, magnesium, aluminum, or copper.

< first Cooling channel 9a >

The first cooling flow path 9a is a flow path for cooling the working fluid discharged from the torque converter 3. The first cooling flow path 9a extends inside the torque converter housing 7. In the present embodiment, the first cooling passage 9a is formed only in the upper half of the torque converter housing 7 (see fig. 2).

The first cooling channel 9a extends from the center portion to the outer peripheral portion of the side wall portion 71, and then extends the outer wall portion 72 beyond the torque converter 3 in the axial direction. The first cooling channel 9a communicates with the working fluid reservoir 8.

As shown in fig. 7 or 8, the first cooling channel 9a has a plurality of paths in the side wall portion 71. In the present embodiment, the first cooling channel 9a is divided into two paths in the side wall portion 71. The first cooling channel 9a extends in a meandering manner, not linearly from the central portion to the outer peripheral portion, in the side wall portion 71.

The first cooling channel 9a may have a plurality of paths in the outer wall portion 72. In the present embodiment, for example, the first cooling channel 9a is divided into three paths in the outer wall portion 72. The first cooling channel 9a extends linearly in the axial direction in the outer wall portion 72, but may extend in a meandering manner.

[ working fluid reservoir 8]

As shown in fig. 6, the working fluid reservoir portion 8 is arranged to sandwich the torque converter 3 in cooperation with the side wall portion 71 in the axial direction. That is, the working fluid reservoir portion 8, the torque converter 3, and the side wall portion 71 are arranged in this order in the axial direction. The working fluid reservoir 8 is disposed in the gear case 42. The working fluid reservoir 8 is disposed above the rotation axis O.

The working fluid reservoir portion 8 contains therein a working fluid to be supplied to the torque converter 3. The working fluid reservoir 8 has a supply hole 81 in the bottom surface. The working fluid discharged from the supply hole 81 is supplied to the torque converter 3 through the flow passage 106 between the fixed shaft 104 and the second boss portion 323a of the impeller hub 323.

Specifically, the working fluid in the flow passage 106 is supplied into the torus T through the supply flow passage 324 by the centrifugal force generated by the rotation of the impeller 32 of the torque converter 3. The working fluid discharged from the torque converter 3 flows through the communication passage 51 to the first cooling passage 9 a. The working fluid cooled by passing through the first cooling channel 9a is returned to the working fluid reservoir 8.

[ modified examples ]

While the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention.

Modification example 1

For example, as shown in fig. 9, the torque converter unit may also have a second cooling flow path 9 b. The second cooling flow path 9b extends in a vehicle interior 107 of a vehicle in which the torque converter unit is mounted. The working fluid discharged from the torque converter 3 flows through the second cooling passage 9 b. The working fluid flowing through the second cooling channel 9b is cooled by heat dissipation into the vehicle interior 107.

The working fluid is supplied to the second cooling passage 9b from the communication passage 51. The second cooling channel 9b returns the working fluid to the working fluid reservoir 8.

The torque converter unit also has a selection mechanism 11. The selection mechanism 11 is configured to select one of the first cooling channel 9a and the second cooling channel 9b as a cooling channel for supplying the working fluid discharged from the torque converter 3.

Modification 2

As shown in fig. 10, the torque converter 3 may also have a plurality of elastic members 38. The elastic member 38 is disposed between the first one-way clutch 35 and the cover 31 in the circumferential direction. The elastic member 38 transmits the torque from the cover 31 in the reverse direction to the first one-way clutch 35. Note that, when the cover 31 is rotated in the reverse rotation direction with respect to the first one-way clutch 35 by more than a predetermined angle, the first limit surface 314 of the cover 31 abuts against the second limit surface 351 of the first one-way clutch 35. As a result, the torque from the cover 31 is directly transmitted to the first one-way clutch 35.

In this way, at the time of reverse rotation, the torque from the cover 31 is first transmitted to the first one-way clutch 35 via the elastic member 38, and abrupt torque transmission can be mitigated.

Note that the elastic member 38 may be disposed between the first one-way clutch 35 and the turbine 33 in the circumferential direction. In this case, the elastic member 38 transmits the torque from the first one-way clutch 35 in the reverse rotation direction to the turbine 33.

Modification 3

As shown in fig. 11, the power transmission mechanism may include a planetary gear mechanism 400 and a clutch 401. The planetary gear mechanism 400 has a sun gear 402, a plurality of planetary gears 403, a carrier 404, and a ring gear 405.

Sun gear 402 is mounted to input shaft 5. The sun gear 402 rotates integrally with the input shaft 5. The carrier 404 is mounted to the output shaft 6. The carrier 404 rotates integrally with the output shaft 6.

The clutch 401 is disposed between a member that cannot rotate (for example, the reduction gear case 42 or the prime mover case 21) and the ring gear 405. Further, the clutch 401 is configured to brake rotation of the ring gear 405.

The clutch 401 is, for example, a one-way clutch. The clutch 401 enables the ring gear 405 to rotate when the input shaft 5 and the output shaft 6 rotate in the normal direction. On the other hand, the clutch 401 disables the ring gear 405 from rotating when the input shaft 5 and the output shaft 6 rotate in the reverse direction.

With this configuration, when the input shaft 5 and the output shaft 6 rotate in the normal direction, that is, when the vehicle moves forward, the ring gear 405 rotates without being fixed, and therefore the amplification action in the planetary gear mechanism 400 is not exerted. Therefore, the torque from the prime mover 2 is transmitted to the drive wheels 101 via the torque converter 3 and the reduction gear 4.

On the other hand, when the input shaft 5 and the output shaft 6 rotate in the reverse direction, that is, when the vehicle moves backward, the ring gear 405 is not rotated by the clutch 401, and therefore, the amplification action of the planetary gear mechanism 400 is exerted. Therefore, the torque from the prime mover 2 is amplified by the planetary gear mechanism 400 and transmitted to the drive wheels 101 via the reduction gear 4.