Motor unit

Abstract

This motor unit comprises: a rotating shaft (3) supported so as to be rotatable about an axis with respect to a housing (2); a motor unit (1) provided with a stator (21) and a rotor (24) and applying a driving force to a motor shaft (30) fixed to the rotor (24); and a clutch (60) disposed between the motor shaft (30) and the rotating shaft (3). The clutch (60) includes a multi-plate clutch mechanism (40) and a hydraulic mechanism (50) for switching between a fastening state and a fastening release state of the multi-plate clutch mechanism (40). The hydraulic mechanism (50) includes a supply oil path (51) for supplying oil and a solenoid valve (52) for opening and closing the supply oil path (51).

Description

Motor unit

[0001] The present invention relates to a motor unit used in an electric vehicle.

[0002] In electric vehicles equipped with a motor (rotating electric machine) as a driving source for traveling, the motor is driven by electricity stored in a battery or electricity generated while traveling. The motor also functions as a generator that generates regenerative power, mainly during coasting. The number and locations of motors installed vary, with some examples being installed only on the front wheel side (front motor example) and others being installed on both the front and rear wheel sides.

[0003] In electric vehicles, when the motor is not being driven (off-drive), external forces from the drivetrain that rotates as the vehicle travels can cause the motor's rotating shaft to be dragged around. In particular, when an IPM motor (Interior Permanent Magnet motor), which has a structure in which a permanent magnet is embedded in the rotor, is used as the motor, dragging the motor's rotating shaft generates drag torque (regenerative torque) due to induced voltage. This generates unnecessary deceleration force in the vehicle, which can lead to deterioration in power consumption and fuel economy.

[0004] Furthermore, in hybrid vehicles equipped with a motor and an engine as a driving source, of the three driving modes—electric drive mode (EV mode), series drive mode, and parallel drive mode—motor drag tends to cause a significant deterioration in electricity consumption and fuel economy, especially in parallel drive mode, because the higher the rotation speed, the greater the loss.

[0005] Therefore, for example, if a clutch is disposed between the motor and the drive system as in Patent Document 1, the dragging state of the motor can be avoided by disengaging the clutch when necessary.

[0006] Japanese Patent Application Laid-Open No. 2021-110348 (see paragraphs 0028 to 0032 on page 6, Figure 1 on page 19, etc.)

[0007] Placing a clutch between the motor and the drivetrain, as in Patent Document 1, requires more space for arranging the device, and the additional device also leads to higher costs. This has a particularly large impact on all-wheel drive vehicles that have motors on both the front and rear wheels, as there are many locations where the motors must be installed.

[0008] Therefore, an object of the present invention is to eliminate the dragging state of the motor while minimizing the increase in the size of the device.

[0009] In order to solve the above problems, the present invention employs a motor unit comprising: a rotating shaft supported on a housing so as to be rotatable about its axis; a motor unit having a stator and a rotor and applying a driving force to a motor shaft fixed to the rotor; and a clutch arranged between the motor shaft and the rotating shaft, the clutch comprising a multi-plate clutch mechanism and a hydraulic mechanism for switching between an engaged state and a disengaged state of the multi-plate clutch mechanism, the hydraulic mechanism comprising a supply oil passage for supplying oil and an electromagnetic valve for opening and closing the supply oil passage (Configuration 1).

[0010] In configuration 1, the multi-plate clutch mechanism includes a plurality of friction plates, and the hydraulic mechanism includes a hydraulic chamber connected to the supply oil passage and formed inside the motor shaft, and a pressure plate that presses the friction plates with the oil pressure in the hydraulic chamber, and a configuration can be adopted in which the oil in the hydraulic chamber is discharged from a discharge passage provided in the motor shaft to a cooling oil passage formed inside the rotor (configuration 2).

[0011] In the configuration 2, the cooling oil passage may be configured to face a permanent magnet fixed to the rotor (configuration 3).

[0012] In addition, in configuration 2 or 3, a configuration can be adopted in which the coil ends of the coils provided in the electromagnets fixed to the stator protrude from the axial end face of the stator, the cooling oil passage has an opening on the axial end face of the rotor, and the opening and the coil ends face each other in a radial direction perpendicular to the axial direction (configuration 4).

[0013] In addition, in any one of configurations 2 to 4, the multi-plate clutch mechanism can be a wet multi-plate clutch in which the friction plates are arranged in a clutch oil chamber, the hydraulic chamber and the clutch oil chamber are connected by an oil passage within the clutch, and the discharge passage is drawn out from the clutch oil chamber (configuration 5).

[0014] A hybrid vehicle equipped with a motor unit and an engine of any one of configurations 1 to 5 as a driving source for traveling can be adopted, in which the solenoid valve is opened and the clutch is engaged when the driving force of the motor unit is required, and the solenoid valve is closed and the clutch is disengaged when the driving force of the motor unit is no longer required in a parallel driving mode in which the hybrid vehicle travels using the driving force of the motor unit and the engine (configuration 6).

[0015] According to this invention, it is possible to eliminate the dragging state of the motor while minimizing the increase in the size of the device.

[0016] Fig. 1 is a longitudinal sectional view of a motor unit according to an embodiment of the present invention, showing a disengaged state. Fig. 2 is a longitudinal sectional view of the motor unit of Fig. 1, showing an engaged state. Fig. 3 is a front view of a rotor. Fig. 4 is a front view of an inner clutch plate. Fig. 5 is a front view of an outer clutch plate. Fig. 6 is an overall view of a vehicle equipped with a motor unit.

[0017] An embodiment of the present invention will be described with reference to the drawings. This embodiment is a motor unit 1 used in a hybrid vehicle 70 (hereinafter simply referred to as vehicle 70) equipped with a motor and an engine as a driving source for traveling. The configuration of motor unit 1 is shown in Figures 1 to 4B, and a vehicle 70 equipped with motor unit 1 is shown in Figure 5.

[0018] The vehicle 70 includes a battery 72 that is used primarily as a power source for traveling, and a driving device 71 for traveling. The driving device 71 includes a motor unit 1, a transmission, etc. A control unit (not shown) equipped with an inverter that converts DC current and AC current is provided between the motor unit 1 and an electronic control unit 74. The rotation speed of the motor unit 1 when it is being driven is controlled by the electronic control unit 74 via the inverter in response to input from the driver.

[0019] A drive device 71 equipped with a motor unit 1 is provided for each of the front and rear drive wheels. The rotation supplied from the drive device 71 is transmitted to the front and rear drive wheels via a transmission or the like. When the vehicle 70 is coasting, the rotation of the front and rear wheels is input to the drive device 71.

[0020] The vehicle 70 is also equipped with an engine 73. The rotation of the crankshaft of the engine 73 is transmitted to the drive wheels via a drive force transmission mechanism such as a torque converter, a continuously variable transmission, or a differential, depending on the driving mode. When the clutch is disengaged, the transmission is switched to a disconnected state.

[0021] The electronic control unit 74 has three drive modes set: electric drive mode (EV mode), series drive mode, and parallel drive mode. The electronic control unit 74 provided in the vehicle 70 selects the optimum drive mode depending on the current state and drive condition of the vehicle 70, the driver's request, etc. The motor unit 1, the engine 73, etc. are controlled depending on the selected drive mode.

[0022] 1, the motor unit 1 includes a rotating shaft 3 supported rotatably about its axis in a cylindrical housing 2 having a hollow interior, a motor section 20 housed within the housing 2 and applying driving force to a motor shaft 30, and a clutch 60 also housed within the housing 2 and positioned between the motor shaft 30 and the rotating shaft 3. The rotating shaft 3 is connected to the drive wheels of a vehicle 70 via a driving force transmission path and functions as the output shaft of the motor unit 1.

[0023] The housing 2 is a hollow cylindrical member with end walls 2a, 2b closing both axial ends of a cylindrical portion 2c. One axial end (left side in FIG. 1) of the end wall 2a has an opening through which a motor shaft 30 is inserted, and the other axial end (right side in FIG. 1) has an opening through which a rotating shaft 3 is inserted. The motor shaft 30 is rotatably supported in the opening of the end wall 2a via a bearing 6. The rotating shaft 3 is rotatably supported in the opening of the end wall 2b via a bearing 4.

[0024] The motor section 20 includes a stator 21 having an electromagnet 22 and a rotor 24 having a permanent magnet 23 , and the motor shaft 30 is fixed to the inner diameter of the rotor 24 .

[0025] The stator 21 is cylindrical and press-fitted into the inner diameter of the housing 2. The electromagnet 22 is incorporated between the outer cylindrical portion 21a and the inner cylindrical portion 21b of the stator 21. The electromagnet 22 comprises an electromagnetic coil and a core that supports the electromagnetic coil, and when current is applied to the electromagnetic coil, a magnetic flux flows through the core and the stator 21. Coil ends 22a of the electromagnetic coil protrude in the axial direction from both axial end faces 21c, 21c of the stator 21.

[0026] The rotor 24 is cylindrical and press-fitted onto the outer periphery of the motor shaft 30. The permanent magnet 23 is incorporated between an outer cylindrical portion 24a and an inner cylindrical portion 24b of the rotor 24.

[0027] The motor shaft 30 includes a shaft portion 31 supported by the end wall 2a, a cylindrical portion 32 fixed to the inner diameter of the rotor 24, and an end wall portion 34 radially connecting the other end of the shaft portion 31 and one end of the cylindrical portion 32. The space on the inner diameter side of the cylindrical portion 32 serves as a space (clutch oil chamber 56) for accommodating the multi-plate clutch mechanism 40 that constitutes the clutch 60.

[0028] The clutch 60 includes a multi-plate clutch mechanism 40 and a hydraulic mechanism 50 that switches the multi-plate clutch mechanism 40 between an engaged state and a disengaged state (disengaged state).

[0029] The multi-plate clutch mechanism 40 includes a plurality of friction plates 33, 43. The friction plates 33, 43 are made up of a number of outer clutch plates 33 and a number of inner clutch plates 43. The outer clutch plates 33 and the inner clutch plates 43 are assembled alternately in the axial direction.

[0030] The outer clutch plates 33 are prevented from rotating by a key 33a (see FIG. 4B) fitting into a key groove (not shown) formed in the cylindrical portion 32 of the motor shaft 30, and are supported so as to be movable in the axial direction. On the other hand, the inner clutch plates 43 are prevented from rotating by a key 43a (see FIG. 4A) fitting into a key groove (not shown) formed in a central shaft portion 42 connected to the rotating shaft 3, and are supported so as to be movable in the axial direction. The rotating shaft 3 and the central shaft portion 42 are connected by splines, serrations, etc., with protrusions 3a provided on the rotating shaft 3 fitting into recesses 41 provided in the central shaft portion 42, so that they rotate together about the axis.

[0031] The hydraulic mechanism 50 includes a supply oil passage 51 that supplies oil from a hydraulic supply source (not shown) and a solenoid valve 52 that opens and closes the supply oil passage 51. The supply oil passage 51 is formed along the axis of the shaft portion 31 of the motor shaft 30 and is connected to a hydraulic chamber 53 formed inside the cylindrical portion 32 of the motor shaft 30. In this embodiment, the multi-plate clutch mechanism 40 is a wet-type multi-plate clutch, and the friction plates 33, 43 are disposed in a clutch oil chamber 56 filled with oil. The hydraulic chamber 53 and the clutch oil chamber 56 are in communication with each other via an internal clutch oil passage 57. The other axial side of the clutch oil chamber 56 (the right side in FIG. 1 ) is oil-tightly closed by a seal 7 provided between the rotating shaft 3 and a lid 34 that closes the end of the cylindrical portion 32.

[0032] The hydraulic mechanism 50 includes a pressure plate 61 that presses the friction plates 33, 43 toward the other axial direction (to the right in FIG. 1 ) by hydraulic pressure in a hydraulic chamber 53. The hydraulic chamber 53 and a clutch oil chamber 56 communicate with each other through an internal clutch oil passage 57 formed between the outer diameter of the pressure plate 61 and the inner diameter of the cylindrical portion 32.

[0033] When the solenoid valve 52 is opened, the hydraulic pressure in the hydraulic chamber 53 rises (see arrow A in FIG. 2), and one end surface 61b of the pressure plate 61 is pressed axially toward the other side (see arrow B in FIG. 2). Due to the action of this hydraulic pressure, the other end surface 61a of the pressure plate 61 tightly couples the outer clutch plate 33 and the inner clutch plate 43 to each other, and the multi-plate clutch mechanism 40 enters an engaged state. This allows rotational torque to be transmitted between the motor shaft 30 and the rotating shaft 3. FIG. 2 shows the clutch 60 in an engaged state.

[0034] 2, closing the solenoid valve 52 releases the hydraulic pressure from the hydraulic pressure supply source. Subsequently, when the hydraulic pressure in the hydraulic chamber 53 drops, the pressure plate 61 is pressed axially to one side (the left side in FIG. 2) by the biasing force of an elastic member (not shown), causing the outer clutch plate 33 and the inner clutch plate 43 to move away from each other, placing the multi-plate clutch mechanism 40 in a disengaged state (disengaged state). This prevents rotational torque from being transmitted between the motor shaft 30 and the rotating shaft 3. FIG. 1 shows the clutch 60 in a disengaged state (disengaged state).

[0035] Therefore, when the driving force of the motor unit 1 is no longer needed while the vehicle 70 is running, the solenoid valve 52 is closed and the clutch 60 is disengaged, thereby preventing deterioration in electricity consumption and fuel efficiency due to motor drag. Furthermore, by controlling the solenoid valve 52 to switch between the open and closed states, the motor shaft 30 and the rotating shaft 3 can be easily switched between a directly coupled state and an engaged and disengaged state.

[0036] Furthermore, since the motor unit 1 and the clutch 60 are housed and integrated within the housing 2, the increase in size and bulkiness of the device can be minimized. In particular, by housing the clutch 60 and the hydraulic mechanism 50 in the clutch housing portion 10 formed inside the rotor 24, the device size can be suppressed. Note that in this embodiment, the multi-plate clutch mechanism 40 is used as the clutch 60, so the number of friction plates 33, 43 can be appropriately set depending on the inner diameter of the clutch housing portion 10, i.e., the inner diameter of the cylindrical portion 32 of the motor shaft 30. As a result, by setting the number of friction plates 33, 43 depending on the space available to house the multi-plate clutch mechanism 40 and the motor's transmission torque, torque can be reliably transmitted without gear slippage.

[0037] Oil is sealed inside the housing 2 for the purpose of lubricating and cooling the components. This oil is also used as oil supplied by the hydraulic mechanism 50 to operate the clutch 60. The oil lubricates and cools the contact areas between the friction plates 33, 43 and the pressure plate 61 of the multi-plate clutch mechanism 40.

[0038] As shown in FIG. 2 , oil in the hydraulic chamber 53 is discharged toward the rotor 24 through a cooling oil passage (see arrow C in FIG. 2 ). The cooling oil passage connects a discharge passage 54a provided in the motor shaft 30 to a first cooling oil passage 54b formed inside the rotor 24. Because the oil is gradually discharged toward the inside of the rotor 24 by centrifugal force, cooling of the rotor 24 is promoted. Furthermore, when the solenoid valve 52 is closed, the hydraulic pressure in the hydraulic chamber 53 is quickly reduced, so that the pressure plate 61 smoothly releases the pressure on the friction plates 33, 43. In this case, the elastic member that biases the pressure plate 61 toward one axial side (the left side in FIG. 2 ) can be omitted.

[0039] In this embodiment, the discharge passage 54a and the first cooling oil passage 54b extend in a direction away from the shaft center, i.e., in the radial direction of the cylindrical portion 32 of the motor shaft 30 and the rotor 24, thereby enhancing the oil delivery effect by centrifugal force. Furthermore, as shown in FIG. 1, it is desirable that the center lines of the discharge passage 54a and the first cooling oil passage 54b are continuous and on the same straight line.

[0040] The cooling oil passage also includes a second cooling oil passage 55 connected to the first cooling oil passage 54b. The second cooling oil passage 55 extends axially from the outer diameter side end of the first cooling oil passage 54b on both sides, and includes openings 55a, 55b on both end faces 24c of the rotor 24. The second cooling oil passage 55 faces the permanent magnets 23 fixed to the rotor 24, thereby facilitating cooling of the permanent magnets 23. In the embodiment, the second cooling oil passage 55 faces the permanent magnets 23 over its entire length, further enhancing the cooling effect of the permanent magnets 23.

[0041] Furthermore, coil ends 22a of the electromagnetic coil provided in electromagnet 22 protrude from end faces 21c on both axial sides of stator 21. Furthermore, openings 55a, 55b of second cooling oil passage 55 face coil ends 22a in a radial direction perpendicular to the axial direction. Therefore, as shown by arrow D in Figure 2, oil discharged from the cooling oil passage hits coil ends 22a due to centrifugal force caused by rotation of rotor 24, thereby enabling effective cooling of rotor 24 and coil ends 22a.

[0042] Furthermore, since the multi-plate clutch mechanism 40 is a wet multi-plate clutch in which the friction plates 33, 43 are arranged inside the clutch oil chamber 56, it is also possible to extend the cooling oil passage from the clutch oil chamber 56. That is, although the discharge passage 54a is extended directly from the hydraulic chamber 53 in Figures 1 and 2, this may be modified so that the oil that flows from the hydraulic chamber 53 into the in-clutch oil passage 57 and the clutch oil chamber 56 is discharged to the cooling oil passage through the discharge passage 54a extended from the clutch oil chamber 56. This allows a portion of the oil supplied to the hydraulic chamber 53 to be used as cooling oil for cooling the wet multi-plate clutch.

[0043] In this invention, when the driving force of motor unit 1 is required as a driving force for traveling, solenoid valve 52 is opened and clutch 60 is engaged, and when the driving force of motor unit 1 is no longer required in parallel operation mode, etc., solenoid valve 52 is closed to cut off the supply of hydraulic pressure and clutch 60 is disengaged, thereby suppressing the generation of drag torque.

[0044] That is, in this invention, the clutch 60 in the motor unit 1 prevents the motor shaft 30 of the motor section 20 from being rotated by an external force from the drive wheel side (transaxle side) of the vehicle body. In other words, the motor shaft 30 of the motor section 20 and the output rotating shaft 3 rotate independently, thereby achieving a compact state in which torque is not transmitted. Furthermore, by providing a torque transmission switching mechanism called the clutch 60 in the motor unit 1, the motor shaft 30 and the rotating shaft 3 can be directly connected (connected) when torque transmission is required, and can be disengaged when torque transmission is not required. Furthermore, by arranging the friction plates 33, 43 and pressure plate 61 of the multi-plate clutch mechanism 40 that constitutes the clutch 60 and the hydraulic mechanism 50 that operates them inside the rotor 24, an increase in the volume of the device is suppressed.

[0045] In the above embodiment, the wet multi-plate clutch mechanism 40 is used as the clutch 60, but the dry multi-plate clutch mechanism 40 may also be used as the clutch 60.

[0046] Furthermore, in the above embodiment, a hybrid car is assumed as the vehicle 70, but the hybrid car may in particular be a plug-in hybrid car that can charge the battery 72 directly (external charging) using a plug from a household outlet or the like. The motor unit 1 of the present invention can also be applied to an electric vehicle (EV) that has only a motor as a driving source for traveling.

[0047] REFERENCE SIGNS LIST 1 motor unit 2 housing 3 rotating shaft 20 motor section 21 stator 22 electromagnet 22a coil end 23 permanent magnet 24 rotor 30 motor shaft 33, 43 friction plate 40 multi-plate clutch mechanism 50 hydraulic mechanism 52 solenoid valve 53 hydraulic chamber 60 clutch 61 pressure plate 70 vehicle 73 engine

Claims

1. A motor unit comprising: a rotating shaft supported on a housing so as to be rotatable about its axis; a motor unit having a stator and a rotor and applying driving force to a motor shaft fixed to the rotor; and a clutch arranged between the motor shaft and the rotating shaft, wherein the clutch comprises a multi-plate clutch mechanism and a hydraulic mechanism for switching the multi-plate clutch mechanism between an engaged state and a disengaged state, and the hydraulic mechanism comprises a supply oil passage for supplying oil and an electromagnetic valve for opening and closing the supply oil passage.

2. A motor unit as described in claim 1, wherein the multi-plate clutch mechanism comprises a plurality of friction plates, the hydraulic mechanism comprises a hydraulic chamber connected to the supply oil passage and formed inside the motor shaft, and a pressure plate that presses the friction plates with the oil pressure in the hydraulic chamber, and the oil in the hydraulic chamber is discharged from a discharge passage provided on the motor shaft into a cooling oil passage formed inside the rotor.

3. A motor unit according to claim 2, wherein the cooling oil passage faces a permanent magnet fixed to the rotor.

4. A motor unit as described in claim 2 or 3, wherein the coil ends of the coils provided in the electromagnets fixed to the stator protrude from the axial end face of the stator, and the cooling oil passage has an opening on the axial end face of the rotor, and the opening and the coil ends face each other in a radial direction perpendicular to the axial direction.

5. A motor unit according to any one of claims 2 to 4, wherein the multi-plate clutch mechanism is a wet multi-plate clutch in which the friction plates are arranged in a clutch oil chamber, the hydraulic chamber and the clutch oil chamber are connected by an oil passage within the clutch, and the discharge passage is drawn out from the clutch oil chamber.

6. A hybrid vehicle equipped with a motor unit and an engine according to any one of claims 1 to 5 as a driving source for traveling, wherein the hybrid vehicle opens the solenoid valve and engages the clutch when the driving force of the motor unit is required, and closes the solenoid valve and disengages the clutch when the driving force of the motor unit is no longer required in a parallel driving mode in which the hybrid vehicle travels using the driving force of the motor unit and the engine.

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