Drive unit

Abstract

To prevent an auxiliary electric motor from being rotated exceeding a maximum rated voltage.SOLUTION: A drive unit 100 includes a driving source 2, a shaft 3, an auxiliary electric motor 4, and a clutch 5, the shaft 3 serving for transmitting torque output by the driving source 2, the clutch 5 being arranged between the shaft 3 and the auxiliary electric motor 4, the clutch 5 serving for transmitting positive-reverse rotation power from the auxiliary electric motor 4 to the shaft 3, and for interrupting positive-reverse rotation torque transmission from the shaft 3 to the auxiliary electric motor 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A drive unit has been proposed that has not only a drive source such as an electric motor or an engine, but also an auxiliary electric motor that outputs torque in an auxiliary manner. For example, a drive device disclosed in Patent Document 1 has an engine and an auxiliary electric motor, in which the engine is the main drive source and the auxiliary electric motor assists the torque of the engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-160096 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the drive unit described above, when the drive source rotates at high speed, the rotation of the drive source is transmitted to the auxiliary electric motor, causing the auxiliary electric motor to rotate at high speed, which may cause the back electromotive force of the auxiliary electric motor to exceed the maximum rated voltage.

[0005] An object of the present invention is to prevent an auxiliary electric motor from rotating above its maximum rated voltage. [Means for solving the problem]

[0006] A drive unit according to a first aspect includes a drive source, a shaft, an auxiliary electric motor, and a clutch. The shaft is configured to transmit torque output from the drive source. The clutch is disposed between the shaft and the auxiliary electric motor. The clutch is configured to transmit power in forward and reverse rotation from the auxiliary electric motor to the shaft, and to interrupt transmission of torque in forward and reverse rotation from the shaft to the auxiliary electric motor.

[0007] With this configuration, even if the drive source rotates at a rotational speed that exceeds the maximum rated voltage of the auxiliary electric motor, the clutch does not transmit the rotation of the drive source to the auxiliary electric motor, thereby preventing the auxiliary electric motor from rotating at a speed that exceeds the maximum rated voltage.

[0008] The drive unit according to the second aspect is configured as follows in the drive unit according to the first aspect: The drive source is a main electric motor.

[0009] The drive unit according to the third aspect is configured as follows in the drive unit according to the second aspect: The auxiliary electric motor has characteristics of a lower maximum rotation speed and a higher maximum torque than the main electric motor.

[0010] A drive unit according to a fourth aspect is the drive unit according to any one of the first to third aspects, and is configured as follows: The auxiliary electric motor is disposed coaxially with the drive source.

[0011] A drive unit according to a fifth aspect is the drive unit according to any one of the first to third aspects, and is configured as follows: The auxiliary electric motor is arranged on a separate axis from the drive source.

[0012] A drive unit according to a sixth aspect is the drive unit according to any one of the first to fifth aspects, further comprising a control unit. The control unit is configured to control the drive source and the auxiliary electric motor. The control unit drives at least the auxiliary electric motor when the vehicle speed is equal to or less than a threshold. Furthermore, the control unit drives the drive source and stops the auxiliary electric motor when the vehicle speed exceeds the threshold. Note that stopping the auxiliary electric motor means stopping the supply of energy to the auxiliary electric motor.

[0013] A drive unit according to a seventh aspect is the drive unit according to any one of the first to fifth aspects, further comprising a controller. The controller is configured to control the drive source and the auxiliary electric motor. When the vehicle speed is equal to or less than a first threshold, the controller drives the drive source and the auxiliary electric motor. When the vehicle speed exceeds the first threshold, the controller drives the drive source and stops the auxiliary electric motor. When the vehicle speed is equal to or less than a second threshold lower than the first threshold and the required torque is equal to or less than a third threshold, the controller stops the drive source and drives the auxiliary electric motor. Note that stopping the drive source means stopping the supply of energy to the drive source, and the drive source may be rotated by the torque of the auxiliary electric motor.

[0014] A drive unit according to an eighth aspect is the drive unit according to any one of the first to seventh aspects, and is configured as follows: The clutch has an input rotating member, an output rotating member, and a transmission member. The input rotating member is configured to receive torque from an auxiliary electric motor. The output rotating member is configured to output torque to the shaft. The output rotating member is arranged at a radial distance from the input rotating member. The transmission member is arranged between the input rotating member and the output rotating member. The transmission member can be in a disengaged state in which there is a gap between the input rotating member and the output rotating member, and an engaged state in which the input rotating member and the output rotating member are meshed with each other. When the input rotating member rotates relative to the transmission member, the transmission member is in the engaged state.

[0015] A drive unit according to a ninth aspect is the drive unit according to the eighth aspect, and is configured as follows: The clutch has a biasing member that biases the transmission member to a disengaged state.

[0016] A drive unit according to a tenth aspect is the drive unit according to the eighth or ninth aspect, and is configured as follows: the clutch has a retaining member disposed between the input rotating member and the output rotating member. The retaining member is disposed so as to be rotatable relative to the input rotating member and the output rotating member. The retaining member retains the transmission member. Effect of the Invention

[0017] According to the present invention, the auxiliary electric motor can be prevented from rotating above the maximum rated voltage. [Brief description of the drawings]

[0018] [Figure 1] FIG. [Diagram 2] 5 is a graph showing characteristics of a main electric motor and an auxiliary electric motor. [Diagram 3] FIG. 2 is an enlarged view of the clutch in a disengaged state. [Figure 4] An enlarged view of the clutch in the engaged state. [Diagram 5] An enlarged view of the clutch in the engaged state. [Figure 6] 6 is a flowchart showing an example of a control method of the control unit. [Figure 7] FIG. 11 is a schematic diagram showing a drive unit according to a modified example. [Figure 8] FIG. 11 is a schematic diagram showing a drive unit according to a modified example. [Figure 9] 10 is a flowchart showing an example of a control method of a control unit according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the drive unit according to this embodiment will be described with reference to the drawings.

[0020] <Drive unit> 1, the drive unit 100 includes a main electric motor 2 (an example of a drive source), a shaft 3, an auxiliary electric motor 4, a clutch 5, and a control unit 6. The drive unit 100 is configured to drive drive wheels (not shown). The drive unit 100 is mounted on, for example, an electric vehicle or a hybrid vehicle.

[0021] <Main electric motor> The main electric motor 2 is configured to output forward and reverse torque to drive the drive wheels. Note that forward rotation refers to the rotation of each member when the vehicle equipped with the drive unit 100 moves forward. That is, when the main electric motor 2 outputs forward torque, each member rotates forward and the vehicle moves forward. Note that reverse rotation refers to the rotation of each member when the vehicle equipped with the drive unit 100 moves backward. That is, when the main electric motor 2 outputs reverse torque, each member rotates reverse and the vehicle moves backward.

[0022] <Shaft> The shaft 3 is arranged to be rotatable. The shaft 3 is directly or indirectly attached to the main electric motor 2. In this embodiment, the shaft 3 is arranged coaxially with the main electric motor 2. Torque from the main electric motor 2 is input to the shaft 3. The shaft 3 transmits the torque from the main electric motor 2 to the drive wheels.

[0023] <Auxiliary electric motor> The auxiliary electric motor 4 is configured to output torque for forward and reverse rotation. The auxiliary electric motor 4 has a rotor 41 and a stator 42. The stator 42 is fixed to a frame or the like. The auxiliary electric motor 4 is disposed coaxially with the main electric motor 2. In other words, the rotation shaft of the auxiliary electric motor 4 is disposed coaxially with the rotation shaft of the main electric motor 2.

[0024] The auxiliary electric motor 4 is configured to output forward and reverse rotation torque to the drive wheels via the shaft 3. Fig. 2 is a graph showing the characteristics of the main electric motor 2 and the auxiliary electric motor 4. The solid line in Fig. 2 shows the characteristics of the main electric motor 2, and the dashed line shows the characteristics of the auxiliary electric motor 4.

[0025] 2, the auxiliary electric motor 4 has characteristics of a lower maximum rotation speed and a higher maximum torque than the main electric motor 2. In other words, the auxiliary electric motor 4 is suitable for outputting torque in a low speed range.

[0026] <Clutch> As shown in Fig. 1, the clutch 5 is attached between the shaft 3 and the auxiliary electric motor 4. The clutch 5 is configured to transmit power in forward and reverse rotation from the auxiliary electric motor 4 to the shaft 3, and to interrupt the transmission of torque in forward and reverse rotation from the shaft 3 to the auxiliary electric motor 4. In other words, the clutch 5 can be in a transmitting state and a non-transmitting state.

[0027] 3 is an enlarged view showing the clutch 5 in a non-transmitting state. In the following description, the axial direction means the direction in which the rotation shaft of the clutch 5 extends. The radial direction means the radial direction of a circle centered on the rotation shaft of the clutch 5, and the circumferential direction means the circumferential direction of a circle centered on the rotation shaft of the clutch 5.

[0028] As shown in FIG. 3, the clutch 5 includes an outer ring 51 (an example of an input rotating member), an inner ring 52 (an example of an output rotating member), a plurality of rollers 53 (an example of a transmission member), a plurality of pairs of biasing members 54, a retaining member 55, and a cam mechanism 56.

[0029] <Outer ring> The outer ring 51 is annular. The outer ring 51 is disposed radially outward from the inner ring 52. The outer ring 51 is rotatable about a rotation axis. The outer ring 51 is rotatable relative to the inner ring 52. Torque from the auxiliary electric motor 4 is input to the outer ring 51. The outer ring 51 is attached to a member on the auxiliary electric motor 4 side. The outer ring 51 is directly or indirectly attached to the rotor 41 of the auxiliary electric motor 4.

[0030] A plurality of cam surfaces 512 are formed on the inner peripheral surface of the outer ring 51. The cam surfaces 512 are formed at intervals in the circumferential direction. Preferably, the cam surfaces 512 are disposed at equal intervals in the circumferential direction.

[0031] Each cam surface 512 is configured to be recessed radially outward. The circumferential center of cam surface 512 is the farthest from the inner peripheral surface of inner ring 52. Also, each cam surface 512 is configured to approach inner ring 52 as it approaches both circumferential ends. Specifically, each cam surface 512 is formed in an arc shape when viewed in the axial direction.

[0032] <Inner circle> The inner ring 52 is disposed at a distance from the outer ring 51 in the radial direction. Specifically, the inner ring 52 is disposed radially inward relative to the outer ring 51. The inner ring 52 is attached to a member on the drive wheel side. Specifically, the inner ring 52 is attached to the shaft 3. The inner ring 52 is configured to output torque to the shaft 3. The inner ring 52 is rotatable about the rotation axis. The inner ring 52 is rotatable relative to the outer ring 51.

[0033] <Retaining material> The holding member 55 is disposed between the outer ring 51 and the inner ring 52. The holding member 55 holds the rollers 53 and the biasing members 54. The holding member 55 is disposed so as to be rotatable relative to the outer ring 51 and the inner ring 52.

[0034] <Laura> The rollers 53 are held by a holding member 55. More specifically, the rollers 53 are held by the holding member 55 via a pair of biasing members 54. Each roller 53 has a cylindrical shape extending in the axial direction. The rollers 53 are disposed between the outer ring 51 and the inner ring 52 in the radial direction.

[0035] The roller 53 can be in a non-engaged state or an engaged state. As shown in Fig. 3, the non-engaged state indicates a state in which the roller 53 has a gap between it and the inner ring 52. That is, when the roller 53 is in the non-engaged state, it is not meshed with the outer ring 51 and the inner ring 52. Specifically, when the roller 53 is in the non-engaged state, it is located in the center of the cam surface 512 in the circumferential direction.

[0036] 4 or 5, the engaged state refers to a position where roller 53 is engaged between outer ring 51 and inner ring 52. Specifically, when roller 53 is in the engaged state, roller 53 is located at a position moved from the center of cam surface 512 to both ends. When roller 53 is in the engaged state, clutch 5 is in a transmission state.

[0037] [Forced member] 3, the pairs of biasing members 54 are configured to urge roller 53 toward outer ring 51 by sandwiching roller 53 in the circumferential direction. Each biasing member 54 is held by a holding member 55. Biasing member 54 may be, for example, a leaf spring or a coil spring. In this manner, each biasing member 54 biases roller 53 so that roller 53 is in the non-transmitting state.

[0038] [Cam mechanism] The cam mechanism 56 is configured to cause the roller 53 to mesh between the inner ring 52 and the outer ring 51 when the outer ring 51 rotates relative to the holding member 55. Specifically, the cam mechanism 56 has a cam surface 512 formed on the outer peripheral surface of the outer ring 51.

[0039] <Control Unit> As shown in Fig. 1, the control unit 6 is configured to control the main electric motor 2 and the auxiliary electric motor 4. The control unit 6 is configured by, for example, a computer (e.g., a microcomputer) equipped with a CPU (Central Processing Unit) and a ROM (Read Only Memory), etc. Programs for performing various calculations are stored in the ROM. The CPU executes the programs stored in the ROM.

[0040] Fig. 6 is a flowchart showing an example of a control method by the control unit 6. As shown in Fig. 6, when the driver operates the accelerator, the control unit 6 acquires vehicle speed information related to the vehicle speed from a vehicle speed sensor or the like (step S1). Based on the vehicle speed information, the control unit 6 determines whether the vehicle speed is equal to or lower than a threshold value (step S2).

[0041] When the control unit 6 determines that the vehicle speed is equal to or lower than the threshold value (Yes in step S2), it drives the main electric motor 2 and the auxiliary electric motor 4 (step S3). Note that the control unit 6 may drive only the auxiliary electric motor 4 without driving the main electric motor 2.

[0042] When the control unit 6 drives the auxiliary electric motor 4 in this way, during forward travel, the auxiliary electric motor 4 outputs a torque for forward rotation, and the outer ring 51 rotates forward. Here, the rotation speed of the holding member 55 becomes slower than that of the outer ring 51 due to inertia, so the outer ring 51 rotates forward relative to the holding member 55. Then, as shown in FIG. 4, the roller 53 transitions from a non-engaged state to an engaged state, and the roller 53 meshes between the outer ring 51 and the inner ring 52. As a result, the outer ring 51 and the inner ring 52 rotate forward integrally. That is, torque is transmitted from the outer ring 51 to the inner ring 52 via the rollers 53. Therefore, the clutch 5 transmits the torque for forward rotation from the auxiliary electric motor 4 to the shaft 3.

[0043] In addition, when the vehicle is moving backward, when the control unit 6 drives the auxiliary electric motor 4, the auxiliary electric motor 4 outputs a torque for reverse rotation, and the outer wheel 51 rotates in the reverse direction. Here, the rotation speed of the holding member 55 becomes slower than that of the outer wheel 51 due to inertia, so that the outer wheel 51 rotates in the reverse direction relative to the holding member 55. Then, as shown in FIG. 5, the roller 53 transitions from a non-engaged state to an engaged state, and the roller 53 meshes between the outer wheel 51 and the inner wheel 52. As a result, the outer wheel 51 and the inner wheel 52 rotate in the reverse direction integrally. That is, the torque is transmitted from the outer wheel 51 to the inner wheel 52 via the rollers 53. Therefore, the clutch 5 transmits the torque for reverse rotation from the auxiliary electric motor 4 to the shaft 3.

[0044] Next, when the control unit 6 determines that the vehicle speed exceeds the threshold value (No in step S2), it drives the main electric motor 2 and stops the auxiliary electric motor 4 (step S4). When the main electric motor 2 is driven and the auxiliary electric motor 4 is stopped in this manner, as shown in FIG. 3, the roller 53 transitions to a disengaged state, and the meshing between the outer ring 51 and the inner ring 52 is released. Therefore, for example, even if the shaft 3 rotates forward or backward due to the torque from the main electric motor 2, only the inner ring 52 rotates and the outer ring 51 does not rotate. That is, the clutch 5 cuts off the torque transmission from the shaft 3 to the auxiliary electric motor 4. As a result, it is possible to prevent the auxiliary electric motor 4 from rotating at a high speed and prevent the back electromotive voltage of the auxiliary electric motor 4 from exceeding the maximum rated voltage.

[0045] [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.

[0046] (a) In the above embodiment, an electric motor is used as an example of the drive source. However, the drive source may be something other than an electric motor, such as an engine.

[0047] (b) In the above embodiment, the auxiliary electric motor 4 is arranged coaxially with the main electric motor 2, but the arrangement of the auxiliary electric motor 4 is not limited to this. For example, as shown in FIG. 7, the auxiliary electric motor 4 may be arranged on a different axis from the main electric motor 2. In other words, the rotation shaft of the auxiliary electric motor 4 is arranged on a different axis from the rotation shaft of the main electric motor 2. In this case, the auxiliary electric motor 4 transmits torque to the shaft 3 via a gear, a chain or a belt, and a clutch 5.

[0048] (c) In the above embodiment, the clutch 5 is attached directly to the shaft 3, but the arrangement of the clutch 5 is not limited to this. The clutch 5 only needs to be arranged between the shaft 3 and the auxiliary electric motor 4, and for example, as shown in FIG 8, the clutch 5 may be attached to a shaft 7 different from the shaft 3.

[0049] (d) The control method in the control unit 6 is not limited to the control method described in the above embodiment. Fig. 9 is a flowchart showing an example of a control method in the control unit 6 according to a modified example. As shown in Fig. 9, the control unit 6 acquires vehicle speed information (step S11). Then, based on the vehicle speed information, the control unit 6 determines whether the vehicle speed is equal to or less than a first threshold value (step S12). If the control unit 6 determines that the vehicle speed is not equal to or less than the first threshold value (No in step S12), it drives the main electric motor 2 and stops the auxiliary electric motor 4 (step S13).

[0050] On the other hand, if the control unit 6 determines that the vehicle speed is equal to or less than the first threshold (Yes in step S12), it then determines whether the vehicle speed is equal to or less than the second threshold (step S14).If the control unit 6 determines that the vehicle speed is not equal to or less than the second threshold (No in step S14), it drives the main electric motor 2 and the auxiliary electric motor 4 (step S15).

[0051] When the control unit 6 determines that the vehicle speed is equal to or less than the second threshold (Yes in step S14), it acquires required torque information (step S16). The required torque information is information related to the required torque, such as the depression amount of the accelerator pedal. Based on the required torque information, the control unit 6 determines whether the required torque is equal to or less than a third threshold (step S17).

[0052] If the controller 6 determines that the required torque is not equal to or less than the third threshold (No in step S17), it executes the process of step S15. On the other hand, if the controller 6 determines that the required torque is equal to or less than the third threshold (Yes in step S17), it stops the main electric motor 2 and drives the auxiliary electric motor 4 (step S18). [Explanation of symbols]

[0053] 2: Main electric motor 3: Shaft 4: Auxiliary electric motor 5: Clutch 51: Outer ring 52: Insider 53: Laura 54: Pressing member 55: Retaining member 6: Control section 7: Shaft 100: Drive unit

Claims

1. A driving source; A shaft configured to transmit a torque output from the drive source; An auxiliary electric motor; a clutch disposed between the shaft and the auxiliary electric motor and configured to transmit power in forward and reverse rotation from the auxiliary electric motor to the shaft and to interrupt transmission of torque in forward and reverse rotation from the shaft to the auxiliary electric motor; A drive unit comprising:

2. The drive source is a main electric motor.

2. A drive unit according to claim 1.

3. The auxiliary electric motor has characteristics of a lower maximum rotational speed and a higher maximum torque than the main electric motor. A drive unit according to claim 2.

4. The auxiliary electric motor is disposed coaxially with the drive source.

2. A drive unit according to claim 1.

5. The auxiliary electric motor is disposed on a different axis from the drive source.

2. A drive unit according to claim 1.

6. a controller configured to control the drive source and the auxiliary electric motor; The control unit drives at least the auxiliary electric motor when the vehicle speed is equal to or lower than a threshold, and drives the drive source and stops the auxiliary electric motor when the vehicle speed exceeds the threshold.

2. A drive unit according to claim 1.

7. a controller configured to control the drive source and the auxiliary electric motor; the control unit drives the drive source and the auxiliary electric motor when the vehicle speed is equal to or less than a first threshold, drives the drive source and stops the auxiliary electric motor when the vehicle speed exceeds the first threshold, and stops the drive source and drives the auxiliary electric motor when the vehicle speed is equal to or less than a second threshold that is lower than the first threshold and the required torque is equal to or less than a third threshold.

2. A drive unit according to claim 1.

8. The clutch is an input rotary member configured to receive torque from the auxiliary electric motor; an output rotating member configured to output torque to the shaft and radially spaced from the input rotating member; a transmission member that is disposed between the input rotary member and the output rotary member and that can be in a non-engaged state in which there is a gap between the input rotary member and the output rotary member and in an engaged state in which the input rotary member and the output rotary member mesh with each other; having When the input rotating member rotates relative to the transmission member, the transmission member is in the engaged state.

2. A drive unit according to claim 1.

9. The clutch has a biasing member that biases the transmission member to a disengaged state. A drive unit according to claim 8.

10. The clutch has a retaining member disposed between the input rotary member and the output rotary member, the holding member is disposed so as to be rotatable relative to the input rotary member and the output rotary member, and holds the transmission member. A drive unit according to claim 8 or 9.

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