Driving unit

Abstract

To prevent a movement of a vehicle during parking.SOLUTION: A driving unit 100 includes an electric motor 2, a torque converter 3, a power transmission part 4, a first shaft 5, a second shaft 6, and a first changeover mechanism 7. The torque converter 3 amplifies toque in a first rotation direction of the electric motor 2. The power transmission part 4 has a first forward gear train, and a second forward gear train. The first shaft 5 transmits torque from the electric motor 2 to the torque converter 3. The second shaft 6 transmits torque from the torque converter 3 to the second forward gear train. The first changeover mechanism 7 transmits torque to the first forward gear train from the first shaft 5 in a first forward moving state. The first changeover mechanism 7 is constructed not to transmit torque from the first shaft to the first forward gear train in a first neutral state. The first changeover mechanism is constructed to make the first forward gear train non-rotatable in a lock state.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] An electric vehicle has an electric motor as a drive source. In order to amplify the torque from the electric motor, electric vehicles provided with a torque converter have been proposed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5370233 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle equipped with the above-mentioned drive unit is parked on a slope, there is a risk that the vehicle may move. Therefore, an object of the present invention is to prevent the vehicle from moving when parked. [Means for solving the problem]

[0005] A drive unit according to a first aspect includes an electric motor, a torque converter, a power transmission section, a first shaft, a second shaft, and a first switching mechanism. The torque converter is configured to amplify torque in a first rotational direction of the electric motor. The power transmission section has a first forward gear train and a second forward gear train. The first shaft is configured to transmit torque from the electric motor to the torque converter. The second shaft is configured to be able to transmit torque from the torque converter to the second forward gear train. The first switching mechanism is configured to switch between a first forward state, a first neutral state, and a locked state. The first switching mechanism is configured to transmit torque from the first shaft to the first forward gear train in the first forward state. The first switching mechanism is configured not to transmit torque from the first shaft to the first forward gear train in the first neutral state. The first switching mechanism is configured to disable the first forward gear train from rotating in the locked state.

[0006] According to this configuration, by locking the first switching mechanism, the first forward gear train is rendered unrotatable, thereby preventing the vehicle from moving when parked.

[0007] The drive unit according to the second aspect is the drive unit according to the first aspect, further including a second switching mechanism. The power transmission section has a reverse gear train. The second switching mechanism is configured to switch between a second forward state, a reverse state, and a second neutral state. The second switching mechanism is configured to transmit torque from the second shaft to the second forward gear train in the second forward state. The second switching mechanism is configured to transmit torque from the second shaft to the reverse gear train in the reverse state. The second switching mechanism is configured not to transmit torque from the second shaft in the second neutral state.

[0008] The drive unit according to the third aspect is configured as follows in the drive unit according to the second aspect: The first forward gear train has a smaller reduction ratio than the second forward gear train.

[0009] A drive unit according to a fourth aspect is the drive unit according to the second or third aspect, further comprising a control unit. The control unit is configured to control the electric motor. The control unit is configured to set the motor characteristics of the electric motor to a high-speed mode when it is determined that the first switching mechanism is in the first forward state, and to set the motor characteristics of the electric motor to a low-speed mode when it is determined that the second switching mechanism is in the second forward state. The low-speed mode has a larger maximum torque and a smaller maximum output than the high-speed mode.

[0010] A drive unit according to a fifth aspect is the drive unit according to any one of the first to fourth aspects, further comprising a clutch. The clutch is configured to transmit torque between the electric motor and the first shaft in an interruptable manner.

[0011] A drive unit according to a sixth aspect is the drive unit according to any one of the first to fifth aspects, and is configured as follows. The first switching mechanism has a first torque output portion, a first torque input portion, a fixed portion, and a first connecting portion. The first torque output portion rotates integrally with the first shaft. The first torque input portion rotates integrally with the first forward gear train. The fixed portion is arranged non-rotatably. The first connecting portion can take a first connecting state, a second connecting state, and a first non-connecting state. In the first connecting state, the first connecting portion connects the first torque output portion and the first torque input portion. In the second connecting state, the first connecting portion connects the second torque input portion and the fixed portion. In the first non-connecting state, the first connecting portion does not take either the first connecting state or the second connecting state.

[0012] A drive unit according to a seventh aspect is the drive unit according to any one of the second to fourth aspects, and is configured as follows. The second switching mechanism has a second torque output portion, a second torque input portion, a third torque input portion, and a second connecting portion. The second torque output portion rotates integrally with the second shaft. The second torque input portion rotates integrally with the second forward gear train. The third torque input portion rotates integrally with the reverse gear train. The second connecting portion can be in a third connecting state, a fourth connecting state, and a second non-connecting state. In the third connecting state, the second connecting portion connects the second torque output portion and the second torque input portion. In the fourth connecting state, the second connecting portion connects the second torque output portion and the third torque input portion. In the second non-connecting state, the second connecting portion does not take either the third connecting state or the fourth connecting state. Effect of the Invention

[0013] According to the present invention, it is possible to prevent the vehicle from moving when parked. [Brief description of the drawings]

[0014] [Figure 1] FIG. [Diagram 2] FIG. 4 is an enlarged view of the first and second switching mechanisms. [Diagram 3] FIG. 4 is an enlarged view of the first and second switching mechanisms. [Figure 4] FIG. 4 is an enlarged view of the first and second switching mechanisms. [Diagram 5] FIG. 4 is an enlarged view of the first and second switching mechanisms. [Figure 6] 3 is a graph showing characteristics of an electric motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the drive unit will be described with reference to the drawings. Fig. 1 is a schematic diagram of a drive unit 100 according to this embodiment. In the following description, the axial direction is the direction in which the rotation axis O of the electric motor 2 or the torque converter 3 extends. 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. The forward rotation is the rotation when the vehicle moves forward, and the reverse rotation is the rotation when the vehicle moves backward.

[0016] [Drive unit 100] 1, the drive unit 100 includes an electric motor 2, a torque converter 3, a power transmission unit 4, a first shaft 5, a second shaft 6, a first switching mechanism 7, a second switching mechanism 8, and a control unit 9. The drive unit 100 is mounted on, for example, an electric vehicle. The drive unit 100 is configured to drive drive wheels 105.

[0017] <Electric motor 2> The electric motor 2 has a motor case 21, a motor stator 22, and a rotor 23. The electric motor 2 in this embodiment is a so-called inner rotor type motor. The motor case 21 is fixed to a vehicle body frame or the like and cannot rotate. The motor stator 22 and the rotor 23 are housed within this motor case 21.

[0018] The motor stator 22 is fixed to an inner circumferential surface of the motor case 21. The motor stator 22 is non-rotatable. The rotor 23 rotates around a rotation axis O. The rotor 23 is disposed radially inside the motor stator 22. The motor stator 22 is disposed with a gap between it and the rotor 23 in the radial direction.

[0019] <Torque converter 3> The torque converter 3 is disposed axially away from the electric motor 2. The power transmission unit 4 is disposed between the torque converter 3 and the electric motor 2. The electric motor 2, the power transmission unit 4, and the torque converter 3 are arranged in this order in the axial direction.

[0020] The torque converter 3 is rotatably arranged. A rotation axis O of the torque converter 3 substantially coincides with a rotation axis O of the electric motor 2. The torque converter 3 receives torque from the electric motor 2. The torque converter 3 is configured to amplify the torque of the electric motor 2 in a first rotation direction.

[0021] The torque converter 3 has a cover 31, an impeller 32, a turbine 33, a stator 34, a first one-way clutch 36, and a centrifugal clutch 37. In this embodiment, the cover 31 and the impeller 32 form an outer shell of the torque converter 3.

[0022] In the torque converter 3, an impeller 32 is disposed on the electric motor 2 side (left side in FIG. 1), and a cover 31 is disposed on the opposite side to the electric motor 2 (right side in FIG. 1). The torque converter 3 is housed in a torque converter case 30. A working fluid is supplied into the torque converter 3. The working fluid is, for example, hydraulic oil.

[0023] Torque from the electric motor 2 is input to the cover 31. The cover 31 rotates due to the torque from the electric motor 2. The cover 31 is fixed to the first shaft 5. For example, the cover 31 has a splined hole, and the first shaft 5 is spline-fitted into the splined hole of the cover 31. Therefore, the cover 31 rotates integrally with the first shaft 5. The cover 31 is disposed so as to cover the turbine 33.

[0024] The impeller 32 rotates integrally with the cover 31. Torque from the 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 is rotatably supported by the fixed shaft 104 via a bearing member (not shown). The fixed shaft 104 is cylindrical. The space between the impeller 32 and the fixed shaft 104 is airtightly sealed. The second shaft 6 extends axially within the fixed shaft 104. The fixed shaft 104 extends, for example, from the power transmission unit case 40 or the torque converter case 30. The fixed shaft 104 is non-rotatable.

[0025] The turbine 33 is disposed opposite the impeller 32. In particular, the turbine 33 faces the impeller 32 in the axial direction. Torque is transmitted to the turbine 33 from the impeller 32 via the working fluid.

[0026] A second shaft 6 is attached to the turbine 33. In detail, the second shaft 6 is spline-fitted to the turbine 33. The turbine 33 rotates integrally with the second shaft 6.

[0027] The stator 34 is configured to straighten the hydraulic oil returning from the turbine 33 to the impeller 32. The stator 34 is rotatable around a rotation axis O. For example, the stator 34 is supported by a fixed shaft 104 via a first one-way clutch 36. The stator 34 is disposed between the impeller 32 and the turbine 33 in the axial direction.

[0028] The first one-way clutch 36 is disposed between the fixed shaft 104 and the stator 34. The first one-way clutch 36 is configured to allow the stator 34 to rotate in the forward rotation direction. On the other hand, the first one-way clutch 36 prevents the stator 34 from rotating in the reverse rotation direction. The torque is amplified by the stator 34 and transmitted from the impeller 32 to the turbine 33.

[0029] The centrifugal clutch 37 is attached to the turbine 33 or the second shaft 6. 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 centrifugal force generated by the rotation of the turbine 33. In detail, the centrifugal clutch 37 is configured to transmit torque from the cover 31 to the turbine 33 when the turbine 33 reaches or exceeds a predetermined rotation speed.

[0030] <Power transmission section 4> The power transmission unit 4 is housed in a power transmission unit case 40. The power transmission unit 4 is disposed between the electric motor 2 and the torque converter 3 in the axial direction. The power transmission unit 4 outputs the torque from the torque converter 3 to the output unit 101. The power transmission unit 4 reduces the rotation speed and transmits the power from the torque converter 3 to the output unit 101. That is, the power transmission unit 4 functions as a reducer. The output unit 101 includes a differential gear 102, a pair of drive shafts 103, and driving wheels 105. The output unit 101 may have only the driving wheels 105.

[0031] As shown in FIG. 2, the power transmission unit 4 has a first forward gear train 41, a second forward gear train 42, and a reverse gear train 43. The first forward gear train 41 transmits torque from the first shaft 5 to the output unit 101. In detail, the first forward gear train 41 is configured to output the torque in the first rotation direction output by the electric motor 2 as torque in the forward rotation direction. In other words, the first forward gear train 41 is configured to output the torque in the second rotation direction output by the electric motor 2 as torque in the reverse rotation direction. For this reason, when the electric motor 2 is rotated in the first rotation direction and the torque is output to the drive wheels 105 via the first forward gear train 41, the vehicle moves forward. When the electric motor 2 is rotated in the second rotation direction and the torque is output to the drive wheels 105 via the first forward gear train 41, the vehicle moves backward.

[0032] The first forward gear train 41 has a first gear 41a and a second gear 41b that mesh with each other. The first gear 41a is supported by the first shaft 5 so as to be relatively rotatable. The second gear 41b is supported by a third shaft 44. The second gear 41b rotates integrally with the third shaft 44. The second gear 41b outputs torque from the first gear 41a to the third shaft 44. The third shaft 44 is arranged so as to be rotatable.

[0033] The second forward gear train 42 transmits torque from the second shaft 6 to the output unit 101. In detail, the second forward gear train 42 is configured to output the torque in the first rotational direction output by the electric motor 2 as torque in the forward rotational direction. Therefore, when the electric motor 2 is rotated in the first rotational direction and the torque is output to the drive wheels 105 via the second forward gear train 42, the vehicle moves forward.

[0034] The second forward gear train 42 has a third gear 42a and a fourth gear 42b that mesh with each other. The third gear 42a is supported by the second shaft 6 so as to be rotatable relative to the second shaft 6. The fourth gear 42b is supported by the third shaft 44. The fourth gear 42b rotates integrally with the third shaft 44. The fourth gear 42b outputs torque from the third gear 42a to the third shaft 44. The second forward gear train 42 has a larger reduction ratio than the first forward gear train 41.

[0035] The reverse gear train 43 transmits torque from the second shaft 6 to the output unit 101. In detail, the reverse gear train 43 is configured to output the torque in the first rotational direction output by the electric motor 2 as torque in the reverse rotational direction. Therefore, when the electric motor 2 is rotated in the first rotational direction and the torque is output to the drive wheels 105 via the reverse gear train 43, the vehicle moves backward.

[0036] The reverse gear train 43 has a fifth gear 43a, a sixth gear 43b, and a seventh gear 43c. The fifth gear 43a meshes with the sixth gear 43b. The sixth gear 43b meshes with the seventh gear 43c. The fifth gear 43a is supported by the second shaft 6 so as to be rotatable relative to the second shaft 6. The sixth gear 43b is supported by a countershaft (not shown). The sixth gear 43b transmits torque from the fifth gear 43a to the seventh gear 43c. The seventh gear 43c is supported by the third shaft 44. The seventh gear 43c rotates integrally with the third shaft 44. The seventh gear 43c outputs torque from the sixth gear 43b to the third shaft 44.

[0037] <First shaft 5> As shown in Fig. 1, the first shaft 5 extends in the axial direction from the electric motor 2. Specifically, the first shaft 5 extends from the rotor 23 of the electric motor 2. If the electric motor 2 has an output shaft, the first shaft 5 is attached to the output shaft of the electric motor 2. The first shaft 5 is rotatably arranged. The rotation axis of the first shaft 5 is substantially collinear with the rotation axis of the electric motor 2 and the rotation axis of the torque converter 3.

[0038] The first shaft 5 transmits torque between the electric motor 2 and the torque converter 3. Specifically, the first shaft 5 is configured to transmit torque from the electric motor 2 to the torque converter 3. The first shaft 5 is connected to an impeller 32 of the torque converter 3. Specifically, the first shaft 5 is connected to the impeller 32 via a cover 31. A tip end of the first shaft 5 is attached to the cover 31 of the torque converter 3.

[0039] The first shaft 5 is connected to the electric motor 2 via a clutch 11. This clutch 11 is configured to transmit torque between the first shaft 5 and the electric motor 2 in an interruptible manner. In detail, when the clutch 11 is in a clutch-off state, torque transmission between the electric motor 2 and the first shaft 5 is interrupted. On the other hand, when the clutch 11 is in a clutch-on state, torque is transmitted between the electric motor 2 and the first shaft 5.

[0040] <Second shaft 6> The second shaft 6 transmits torque between the torque converter 3 and the power transmission unit 4. In detail, the second shaft 6 can transmit torque from the torque converter 3 to the second forward gear train 42. Note that by switching the torque transmission path using a second switching mechanism 8 described later, the second shaft 6 can also transmit torque from the torque converter 3 to the reverse gear train 43. The second shaft 6 extends in the axial direction from the torque converter 3 toward the electric motor 2.

[0041] The second shaft 6 is cylindrical. The first shaft 5 extends inside the second shaft 6. The first shaft 5 is solid. One end (the right end in FIG. 1) of the second shaft 6 is attached to the turbine 33 of the torque converter 3. The second shaft 6 is rotatably disposed. The second shaft 6 is rotatably supported, for example, by the power transmission case 40 or the like via a bearing member or the like.

[0042] <First switching mechanism> 2 to 4, the first switching mechanism 7 has a first torque output portion 71, a first torque input portion 72, a fixing portion 73, and a first connecting portion 74. The first switching mechanism 7 further has a first actuator 75 that moves the first connecting portion 74 in the axial direction. The first actuator 75 is controlled by the control portion 9.

[0043] The first torque output portion 71 rotates integrally with the first shaft 5. The first torque output portion 71 is a spline fixed to the first shaft 5. That is, the first torque output portion 71 has a plurality of teeth on its outer circumferential surface. The first torque output portion 71 may be formed of a member separate from the first shaft 5, or may be formed integrally with the first shaft 5 by a single member. The first torque output portion 71 is disposed rotatably about the rotation axis O.

[0044] The first torque input portion 72 is arranged to be rotatable around the rotation axis O. The first torque input portion 72 has approximately the same outer diameter as the first torque output portion 71. The first torque input portion 72 is a spline. That is, the first torque input portion 72 has a plurality of teeth on its outer circumferential surface. The first torque input portion 72 is supported by the first shaft 5 to be rotatable relative thereto. The first torque input portion 72 is arranged to be rotatable relative to the first torque output portion 71.

[0045] The first torque input portion 72 rotates integrally with the first forward gear train 41. In detail, the first torque input portion 72 rotates integrally with the first gear 41a. The first torque input portion 72 is formed integrally with the first gear 41a. The first torque input portion 72 may be configured by one member together with the first gear 41a, or may be configured by a separate member.

[0046] The fixed portion 73 is a spline. That is, the fixed portion 73 has a plurality of teeth on its outer circumferential surface. The fixed portion 73 has substantially the same outer diameter as the first torque input portion 72. The fixed portion 73 is arranged so as to be non-rotatable. More specifically, the fixed portion 73 is attached to the power transmission unit case 40. The fixed portion 73 may be formed of one member together with the power transmission unit case 40, or may be formed of a separate member.

[0047] In the axial direction, the first torque input portion 72 is disposed between the first torque output portion 71 and the fixed portion 73. The first torque output portion 71 and the first torque input portion 72 are adjacent to each other in the axial direction, and the first torque input portion 72 and the fixed portion 73 are adjacent to each other in the axial direction.

[0048] The first connecting portion 74 can be in a first connecting state, a second connecting state, and a first non-connecting state. In the first connecting state, the first connecting portion 74 connects the first torque output portion 71 and the first torque input portion 72. In the second connecting state, the first connecting portion 74 connects the first torque input portion 72 and the fixed portion 73. In the first non-connecting state, the first connecting portion 74 does not take either the first connecting state or the second connecting state. Specifically, in the first non-connecting state, the first connecting portion 74 is engaged only with the first torque input portion 72, and is not engaged with the first torque output portion 71 and the fixed portion 73.

[0049] The first connecting portion 74 has a spline hole. That is, the first connecting portion 74 has a plurality of teeth on its inner circumferential surface. The first connecting portion 74 is constantly engaged with the first torque input portion 72 and rotates integrally with the first torque input portion 72. The first connecting portion 74 is rotatable relative to the first shaft 5.

[0050] The first connecting portion 74 is arranged to be movable in the axial direction. As the first connecting portion 74 moves in the axial direction, the first connecting portion 74 switches between a first connected state, a second connected state, and a first non-connected state. As a result, the first switching mechanism 7 switches between a first forward state, a locked state, and a first neutral state. Note that when the first switching mechanism 7 is in the first forward state, the second switching mechanism 8, which will be described later, is in a second neutral state.

[0051] 2, when the first switching mechanism 7 is in the first forward state, the first connecting portion 74 is in the first connecting state and connects the first torque output portion 71 and the first torque input portion 72. In detail, the first connecting portion 74 meshes with the first torque output portion 71 and also meshes with the first torque input portion 72.

[0052] In this manner, the first connecting portion 74 meshes with the first torque output portion 71 and the first torque input portion 72, whereby the first torque output portion 71 and the first torque input portion 72 are connected to each other and rotate integrally. That is, the first shaft 5 and the first gear 41a rotate integrally. In this manner, when the first switching mechanism 7 is in the first forward state, the first switching mechanism 7 transmits torque from the first shaft 5 to the first forward gear train 41.

[0053] 3, when the first switching mechanism 7 is in the locked state, the first connecting portion 74 is in the second connecting state and connects the first torque input portion 72 and the fixed portion 73. In detail, the first connecting portion 74 meshes with the first torque input portion 72 and also meshes with the fixed portion 73.

[0054] In this manner, the first connecting portion 74 meshes with the first torque input portion 72 and the fixed portion 73, thereby rendering the first torque input portion 72 non-rotatable. As a result, the first gear 41a and the second gear 41b constituting the first forward gear train 41 are non-rotatable, and the drive wheels 105 are also non-rotatable. In this manner, when the first switching mechanism 7 is in the locked state, the first switching mechanism 7 renders the first forward gear train 41 non-rotatable.

[0055] 4, when the first switching mechanism 7 is in the first neutral state, the first connecting portion 74 is in a first non-connecting state and is in a state of meshing only with the first torque input portion 72. In this way, the first connecting portion 74 meshes only with the first torque input portion 72 and does not mesh with either the first torque output portion 71 or the fixed portion 73, thereby blocking torque transmission between the first shaft 5 and the first forward gear train 41. In other words, when the first switching mechanism 7 is in the first neutral state, the first switching mechanism 7 does not transmit torque from the first shaft 5 to the first forward gear train 41.

[0056] The first actuator 75 is configured to axially move the first connecting portion 74. The first actuator 75 can be configured by a motor or the like.

[0057] <Second switching mechanism> 4 and 5, the second switching mechanism 8 has a second torque output portion 81, a second torque input portion 82, a third torque input portion 83, and a second connecting portion 84. The second switching mechanism 8 further has a second actuator 85 that moves the second connecting portion 84 in the axial direction. The second actuator 85 is controlled by the control portion 9.

[0058] The second torque output portion 81 rotates integrally with the second shaft 6. The second torque output portion 81 is a spline fixed to the second shaft 6. That is, the second torque output portion 81 has a plurality of teeth on its outer circumferential surface. The second torque output portion 81 may be formed of a member separate from the second shaft 6, or may be formed integrally with the second shaft 6 by a single member. The second torque output portion 81 is disposed rotatably about the rotation axis O.

[0059] The second torque input portion 82 is arranged to be rotatable around the rotation axis O. The second torque input portion 82 has approximately the same outer diameter as the second torque output portion 81. The second torque input portion 82 is a spline. That is, the second torque input portion 82 has a plurality of teeth on its outer circumferential surface. The second torque input portion 82 is supported by the second shaft 6 to be rotatable relative thereto. The second torque input portion 82 is arranged to be rotatable relative to the second torque output portion 81.

[0060] The second torque input portion 82 rotates integrally with the second forward gear train 42. In detail, the second torque input portion 82 rotates integrally with the third gear 42a. The second torque input portion 82 is formed integrally with the third gear 42a. The second torque input portion 82 may be configured by one member together with the third gear 42a, or may be configured by a separate member.

[0061] The third torque input portion 83 is arranged to be rotatable around the rotation axis O. The third torque input portion 83 has approximately the same outer diameter as the second torque output portion 81. The third torque input portion 83 is a spline. That is, the third torque input portion 83 has a plurality of teeth on its outer circumferential surface. The third torque input portion 83 is supported by the second shaft 6 to be rotatable relative thereto. The third torque input portion 83 is arranged to be rotatable relative to the second torque output portion 81.

[0062] The third torque input portion 83 rotates integrally with the reverse gear train 43. In detail, the third torque input portion 83 rotates integrally with the fifth gear 43a. The third torque input portion 83 is formed integrally with the fifth gear 43a. The third torque input portion 83 may be configured by one member together with the fifth gear 43a, or may be configured by a separate member.

[0063] In the axial direction, the second torque output portion 81 is disposed between the second torque input portion 82 and the third torque input portion 83. The second torque output portion 81 and the second torque input portion 82 are adjacent to each other in the axial direction, and the second torque output portion 81 and the third torque input portion 83 are adjacent to each other in the axial direction.

[0064] The second connecting portion 84 can be in a third connecting state, a fourth connecting state, and a second non-connecting state. In the third connecting state, the second connecting portion 84 connects the second torque output portion 81 and the second torque input portion 82. In the fourth connecting state, the second connecting portion 84 connects the second torque output portion 81 and the third torque input portion 83. In the second non-connecting state, the second connecting portion 84 does not take either the third connecting state or the fourth connecting state. Specifically, in the second non-connecting state, the second connecting portion 84 is engaged only with the second torque output portion 81, and is not engaged with the second torque input portion 82 and the third torque input portion 83.

[0065] The second connecting portion 84 has a spline hole. That is, the second connecting portion 84 has a plurality of teeth on its inner circumferential surface. The second connecting portion 84 is constantly engaged with the second torque output portion 81 and rotates integrally therewith.

[0066] The second connecting portion 84 is arranged to be movable in the axial direction. As the second connecting portion 84 moves in the axial direction, the second connecting portion 84 switches between a third connected state, a fourth connected state, and a second non-connected state. As a result, the second switching mechanism 8 switches between a second forward state, a reverse state, and a second neutral state. Note that when the second switching mechanism 8 is in the second forward state or the reverse state, the first switching mechanism 7 is in the first neutral state.

[0067] 4, when the second switching mechanism 8 is in the second forward state, the second connecting portion 84 is in a third connecting state and connects the second torque output portion 81 and the second torque input portion 82. In detail, the second connecting portion 84 meshes with the second torque output portion 81 and also meshes with the second torque input portion 82.

[0068] In this manner, the second connecting portion 84 meshes with the second torque output portion 81 and the second torque input portion 82, whereby the second torque output portion 81 and the second torque input portion 82 are connected to each other and rotate integrally. That is, the second shaft 6 and the third gear 42a rotate integrally. In this manner, when the second switching mechanism 8 is in the second forward state, the second switching mechanism 8 transmits torque from the second shaft 6 to the second forward gear train 42.

[0069] 5, when the second switching mechanism 8 is in the reverse state, the second connecting portion 84 is in the fourth connecting state and connects the second torque output portion 81 and the third torque input portion 83. In detail, the second connecting portion 84 meshes with the second torque output portion 81 and also meshes with the third torque input portion 83.

[0070] In this manner, the second connecting portion 84 meshes with the second torque output portion 81 and the third torque input portion 83, whereby the second torque output portion 81 and the third torque input portion 83 are connected to each other and rotate integrally. That is, the second shaft 6 and the fifth gear 43a rotate integrally. In this manner, when the second switching mechanism 8 is in the reverse state, the second switching mechanism 8 transmits torque from the second shaft 6 to the reverse gear train 43.

[0071] 2 or 3, when the second switching mechanism 8 is in the second neutral state, the second connecting portion 84 is in the second non-connecting state and is in a state of meshing only with the second torque output portion 81. In this manner, the second connecting portion 84 is meshed only with the second torque output portion 81 and is not meshed with either the second torque input portion 82 or the third torque input portion 83, thereby making it possible to block torque transmission between the second shaft 6 and the second forward gear train 42 and between the second shaft 6 and the reverse gear train 43. In other words, when the second switching mechanism 8 is in the second neutral state, the second switching mechanism 8 does not transmit torque from the second shaft 6 to either the second forward gear train 42 or the reverse gear train 43.

[0072] The second actuator 85 is configured to axially move the second connecting portion 84. The second actuator 85 can be configured by a motor or the like.

[0073] <Control Unit> The control unit 9 controls the first actuator 75 to move the first connecting portion 74 in the axial direction. The control unit 9 also controls the second actuator 85 to move the second connecting portion 84 in the axial direction.

[0074] The control unit 9 is configured to control the electric motor 2. In detail, the control unit 9 switches the characteristics of the electric motor 2 between a high speed mode and a low speed mode depending on the state of the drive unit 100.

[0075] FIG. 6 is a graph showing the characteristics of the electric motor 2. In FIG. 6, the solid line indicates the low-speed mode, and the dashed line indicates the high-speed mode. As shown in FIG. 6, in the low-speed mode, the maximum torque is higher and the maximum output is lower than in the high-speed mode. In the high-speed mode, the maximum output is higher and the maximum torque is lower than in the low-speed mode. Also, in the high-speed mode, the maximum rotation speed is higher than in the low-speed mode.

[0076] The control unit 9 acquires position information on the position of the first connecting portion 74 of the first switching mechanism 7 and position information on the position of the second connecting portion 84 of the second switching mechanism 8 from a position sensor or the like. Then, when the control unit 9 determines that the first switching mechanism 7 is in the first forward movement state based on the position information, it sets the motor characteristics of the electric motor 2 to the high speed mode. On the other hand, when the control unit 9 determines that the second switching mechanism 8 is in the second forward movement state, it sets the motor characteristics of the electric motor 2 to the low speed mode.

[0077] [Variations] Although the embodiment of the present invention has 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 basically be applied simultaneously.

[0078] (a) In the above embodiment, the drive unit 100 has the clutch 11, but the configuration of the drive unit 100 is not limited to this. In other words, the drive unit 100 does not have to have the clutch 11.

[0079] (b) In the above embodiment, the control unit 9 is configured to switch the characteristics of the electric motor 2 between a high-speed mode and a low-speed mode, but the configuration of the control unit 9 is not limited to this. For example, the control unit 9 does not have to switch the characteristics of the electric motor 2.

[0080] (c) In the above embodiment, the power transmission unit 4 has the reverse gear train 43, but the configuration of the power transmission unit 4 is not limited to this. For example, the power transmission unit 4 does not have to have the reverse gear train 43. In this case, the electric motor 2 is rotated in the second rotational direction and torque is transmitted via the first forward gear train 41, thereby moving the vehicle backward.

[0081] (d) In the above embodiment, the first connecting portion 74 meshes only with the first torque input portion 72 in the first non-connecting state, but the configuration of the first connecting portion 74 is not limited to this. For example, the first connecting portion 74 may mesh only with the first torque output portion 71 or only with the fixed portion 73 in the first non-connecting state.

[0082] (e) In the above embodiment, the second connecting portion 84 meshed only with the second torque output portion 81 in the second non-connecting state, but the configuration of the second connecting portion 84 is not limited to this. For example, the second connecting portion 84 may mesh only with the second torque input portion 82 or only with the third torque input portion 83 in the second non-connecting state. [Explanation of symbols]

[0083] 2: Electric motor 3: Torque converter 4: Power transmission section 41: 1st forward gear train 42: 2nd forward gear train 43: Reverse gear train 5: First shaft 6: Second shaft 7: First switching mechanism 71: First torque output section 72: First torque input section 73:Fixed part 74: 1st connection part 8: Second switching mechanism 81: Second torque output section 82: Second torque input section 83: 3rd torque input section 84:Second connection part 9: Control section 11: Clutch 100: Drive unit

Claims

1. An electric motor, A torque converter configured to amplify the torque in the first rotation direction of the electric motor, A power transmission unit having a first forward gear train and a second forward gear train, A first shaft configured to transmit torque from the electric motor to the torque converter, A second shaft configured to be able to transmit torque from the torque converter to the second forward gear train, A first switching mechanism configured to switch between a first forward state in which torque is transmitted from the first shaft to the first forward gear train, a first neutral state in which torque is not transmitted from the first shaft to the first forward gear train, and a locked state in which the first forward gear train is non-rotatable, A drive unit comprising the above.

2. Further comprising a second switching mechanism, The power transmission unit has a reverse gear train, The second switching mechanism is configured to switch between a second forward state in which torque is transmitted from the second shaft to the second forward gear train, a reverse state in which torque is transmitted from the second shaft to the reverse gear train, and a second neutral state in which torque from the second shaft is not transmitted, The drive unit according to claim 1.

3. The reduction ratio of the first forward gear train is smaller than that of the second forward gear train, The drive unit according to claim 2.

4. Further comprising a control unit configured to control the electric motor, When the control unit determines that the first switching mechanism is in the first forward state, the control unit sets the motor characteristics of the electric motor to a high-speed mode, and when the control unit determines that the second switching mechanism is in the second forward state, the control unit sets the motor characteristics of the electric motor to a low-speed mode in which the maximum torque is larger and the maximum output is smaller than in the high-speed mode, The drive unit according to claim 2.

5. Further comprising a clutch configured to transmit torque between the electric motor and the first shaft in a torque-interruptible manner, The drive unit according to claim 1.

6. The first switching mechanism, A first torque output portion that rotates integrally with the first shaft, A first torque input portion that rotates integrally with the first forward gear train, A fixed portion arranged to be non-rotatable, A first coupling portion that can take a first coupling state in which the first torque output portion and the first torque input portion are coupled, a second coupling state in which the first torque input portion and the fixed portion are coupled, and a first non-coupling state in which neither the first coupling state nor the second coupling state is taken, having the drive unit according to claim 1. **Claim 7** The second switching mechanism a second torque output portion that rotates integrally with the second shaft, a second torque input portion that rotates integrally with the second forward gear train, a third torque input portion that rotates integrally with the reverse gear train, a second coupling portion that can take a third coupling state in which the second torque output portion and the second torque input portion are coupled, a fourth coupling state in which the second torque output portion and the third torque input portion are coupled, and a second non-coupling state in which neither the third coupling state nor the fourth coupling state is taken, having the drive unit according to claim 2.

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