Vehicular driving device

Abstract

To provide a vehicular driving device which enables a large cabin space or large luggage compartment space of a vehicle to be easily secured and which can be suppressed in the cost.SOLUTION: A vehicular driving device 1 comprises: an electric motor 21; a differential mechanism 22 having a differential case 221 to which driving force generated by the electric motor 21 is input, a first side gear 224, and a second side gear 225; a first hub unit 23 which rotatably supports a left front wheel 11 and transmits the driving force distributed to the first side gear 224 to the left front wheel 11; a second hub unit 31 which rotatably supports a right front wheel 12 and transmits the driving force distributed to the second side gear 225 to the right front wheel 12; a first attachment member 25 to which the electric motor 21, the differential mechanism 22, and the first hub unit 23 are attached; a second attachment member 32 to which the second hub unit 31 is attached; and a drive shaft 4 which couples the second side gear 225 and the second hub unit 31 to each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device that uses an electric motor as a drive source. [Background technology]

[0002] In recent years, various drivetrain layouts have been proposed for vehicles that use electric motors as drive sources. The one described in Patent Document 1 has front and rear drive units each having an electric motor and a transmission, and the output rotation of these drive units is transmitted to the front and rear wheels by left and right drive shafts. The one described in Patent Document 2 has in-wheel motors attached to the left and right rear wheels, and AC current is supplied to the left and right in-wheel motors from left and right inverters, respectively. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-102684 [Patent Document 2] Japanese Patent Publication No. 2020-063010 Summary of the Invention [Problem to be solved by the invention]

[0004] In the system described in Patent Document 1, the drive unit is located in the center of the vehicle width direction, which tends to narrow the vehicle interior space and luggage space. Also, in the system described in Patent Document 2, an in-wheel motor and an inverter must be provided for each of the left and right wheels, which increases costs.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle drive device that can easily ensure a large passenger compartment space or luggage compartment space of a vehicle and can reduce costs. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a vehicle drive device that is mounted on a vehicle having first and second drive wheels on the left and right in a vehicle width direction and drives the first and second drive wheels, the vehicle drive device including: an electric motor that generates a drive force for driving the first and second drive wheels; an input rotary member to which the drive force generated by the electric motor is input; and a differential mechanism that has a first output rotary member and a second output rotary member that are rotatable relative to each other and distributes the drive force input to the input rotary member to the first output rotary member and the second output rotary member while allowing a differential; and a differential mechanism that rotatably supports the first drive wheel. a first bearing mechanism that supports the first drive wheel and transmits the driving force allocated to the first output rotating member to the first drive wheel; a second bearing mechanism that rotatably supports the second drive wheel and transmits the driving force allocated to the second output rotating member to the second drive wheel; a first mounting member to which the electric motor, the differential mechanism, and the first bearing mechanism are attached; a second mounting member to which the second bearing mechanism is attached; and a drive shaft that connects the second output rotating member and the second bearing mechanism and transmits the driving force allocated to the second output rotating member to the second bearing mechanism. [Effects of the Invention]

[0007] According to the vehicle drive device of the present invention, it is easy to ensure a large passenger compartment space or luggage compartment space of the vehicle, and it is possible to reduce costs. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram that schematically shows the general configuration of a vehicle that includes a vehicle drive device according to a first embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing the configuration of a vehicle drive device together with its peripheral members. [Figure 3] FIG. 3 is an enlarged view of a first driving unit in FIG. 2. [Figure 4] FIG. 3 is an enlarged view of a second driving unit in FIG. 2. [Figure 5]FIG. 6 is a cross-sectional view showing the configuration of a vehicle drive device according to a second embodiment of the present invention together with its peripheral members. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 4. The embodiment described below is shown as a preferred specific example for carrying out the present invention, and although various technically preferable technical matters are specifically exemplified, the technical scope of the present invention is not limited to this specific embodiment.

[0010] FIG. 1 is a schematic diagram showing the overall configuration of a vehicle 10 equipped with a vehicle drive system 1 according to a first embodiment of the present invention. The vehicle 10 is capable of traveling on paved roads, and may be, for example, a compact or light vehicle as defined by the Road Transport Vehicle Act, but is not limited thereto and may also be, for example, a passenger cart such as a golf cart. In this embodiment, a case will be described in which a driver steers left and right front wheels 11, 12, which are steerable wheels, by operating a steering wheel 100, but the present invention is not limited thereto and may also be an autonomous vehicle traveling by automatic driving.

[0011] In this embodiment, vehicle 10 is a front-wheel drive vehicle in which left and right front wheels 11, 12 are driven by vehicle drive system 1. Vehicle 10 is equipped with a steering device 18 that steers left and right front wheels 11, 12 in response to steering operation of steering wheel 100. Steering device 18 has a steering shaft 181 connected to steering wheel 100, a rack shaft 182 that moves in the vehicle width direction as steering shaft 181 rotates, and left and right tie rods 185, 186 that are swingably connected to rack shaft 182 via ball joints 183, 184 provided at both ends of rack shaft 182.

[0012] The left and right rear wheels 13, 14 are driven wheels suspended on the vehicle body by rear-wheel suspension devices 19. In the example shown in Figure 1, suspension device 19 is a torsion beam type suspension, and includes trailing arms 191, 192, arm bushings 193, 194, shock absorbers 195, 196, coil springs 197, 198, and a torsion beam 199.

[0013] The vehicle drive system 1 includes a first drive unit 2, a second drive unit 3, and a drive shaft 4 disposed between the first drive unit 2 and the second drive unit 3. In this embodiment, the first drive unit 2 is disposed to the left of the center of the vehicle 10 in the left-right direction, and the second drive unit 3 is disposed to the right of the center of the vehicle 10 in the left-right direction. The left front wheel 11 and the right front wheel 12 are equipped with metal wheels 111, 121 and rubber tires 112, 122, respectively. A portion of the first drive unit 2 is disposed inside the wheel 111 of the left front wheel 11, and a portion of the second drive unit 3 is disposed inside the wheel 121 of the right front wheel 12. The left front wheel 11 corresponds to the first drive wheel of the present invention, and the right front wheel 12 corresponds to the second drive wheel of the present invention. Note that the first drive unit 2 may be provided corresponding to the right front wheel 12, and the second drive unit 3 may be provided corresponding to the left front wheel 11.

[0014] The first drive unit 2 has an electric motor 21 that generates driving force to drive the left front wheel 11 and the right front wheel 12. A portion of the driving force generated by the electric motor 21 is transmitted to the second drive unit 3 side by the drive shaft 4. The vehicle 10 is equipped with a battery 15, an inverter 16, and a control device 17. The inverter 16 converts direct current supplied from the battery 15 into alternating current, which is supplied to the electric motor 21 as a driving current. The inverter 16 has a plurality of switching elements, for example, made of power transistors, and these switching elements are connected in a three-phase bridge configuration. The control device 17 outputs a PMW (Pulse Width Modulation) signal to the inverter 16 that turns on and off the plurality of switching elements, thereby controlling the electric motor 21.

[0015] Fig. 2 is a cross-sectional view showing the configuration of the vehicle drive device 1 together with its peripheral members. Fig. 3 is an enlarged view of the first drive unit 2 in Fig. 2. Fig. 4 is an enlarged view of the second drive unit 3 in Fig. 2. Fig. 2 shows the vehicle drive device 1 in a cross section taken along the vertical direction.

[0016] The first drive unit 2 has an electric motor 21, a differential mechanism 22 combined with the electric motor 21, a first hub unit 23 serving as a first bearing mechanism that rotatably supports the left front wheel 11, and a connecting shaft 24 between the differential mechanism 22 and the first hub unit 23. The first drive unit 2 also has a first mounting member 25 to which the electric motor 21, the differential mechanism 22, the first hub unit 23, and the connecting shaft 24 are attached. The second drive unit 3 has a second hub unit 31 serving as a second bearing mechanism, and a second mounting member 32 to which the second hub unit 31 is attached.

[0017] The first mounting member 25 of the first drive unit 2 and the second mounting member 32 of the second drive unit 3 are suspended by a front-wheel suspension 5. The suspension 5 is a strut-type suspension and has struts 51 and 52 with built-in shock absorbers, coil springs 53 and 54, and lower arms 55 and 56. The first mounting member 25 has a first strut mounting portion 251 to which the strut 51 is attached, a first lower arm mounting portion 252 to which a ball joint 57 for connection with the lower arm 55 is attached, and a first brake device mounting portion 253 to which a first brake device 60 for braking the left front wheel 11 is attached. Similarly, the second mounting member 32 has a second strut mounting portion 321 to which the strut 52 is mounted, a second lower arm mounting portion 322 to which a ball joint 33 for connecting to the lower arm 56 is mounted, and a second brake device mounting portion 323 to which a second brake device 70 for braking the right front wheel 12 is mounted.

[0018] 2, a first kingpin axis 20 is shown by a dashed-dotted line connecting a center point 570 of ball joint 57, which is a connection point of left lower arm 55 to first mounting member 25, and a connection point 510 of strut 51 to the vehicle body, and a second kingpin axis 30 is shown by a dashed-dotted line connecting a center point 330 of ball joint 33, which is a connection point of right lower arm 56 to second mounting member 32, and a connection point 520 of strut 52 to the vehicle body. The first kingpin axis 20 is the steering center line of left front wheel 11 and passes through the portion where tire 112 of left front wheel 11 contacts the road surface. The second kingpin axis 30 is the steering center line of right front wheel 12 and passes through the portion where tire 122 of right front wheel 12 contacts the road surface.

[0019] The drive shaft 4 has a first constant velocity universal joint 41 on the first drive unit 2 side, a second constant velocity universal joint 42 on the second drive unit 3 side, and an intermediate shaft 43 between the first constant velocity universal joint 41 and the second constant velocity universal joint 42. The first constant velocity universal joint 41 has a first outer joint member 411 rotatably supported by the first mounting member 25 of the first drive unit 2, a first inner joint member 412 that is swingable relative to the first outer joint member 411, a plurality of balls 413 arranged between the first outer joint member 411 and the first inner joint member 412, and a cage 414 that holds the plurality of balls 413. A bellows-structured boot 415 covers the space between the first outer joint member 411 and the intermediate shaft 43. As shown in FIG. 3 , the first outer joint member 411 integrally includes a bowl-shaped cup portion 411A and a shaft-like stem portion 411B. The plurality of balls 413 roll in a plurality of ball grooves 411Aa formed in the cup portion 411A of the first outer joint member 411 and a plurality of ball grooves 412a formed in the first inner joint member 412, respectively.

[0020] The second constant velocity universal joint 42 has a configuration similar to that of the first constant velocity universal joint 41. That is, the second constant velocity universal joint 42 has a second outer joint member 421 rotatably supported by the second mounting member 32 of the second drive unit 3, a second inner joint member 422 that is swingable relative to the second outer joint member 421, a plurality of balls 423 arranged between the second outer joint member 421 and the second inner joint member 422, and a cage 424 that holds the plurality of balls 423. The space between the second outer joint member 421 and the intermediate shaft 43 is covered by a boot 425 with a bellows structure. As shown in FIG. 4 , the second outer joint member 421 integrally has a bowl-shaped cup portion 421A and a shaft-like stem portion 421B. The plurality of balls 423 roll in a plurality of ball grooves 421Aa formed in the cup portion 421A of the second outer joint member 421 and a plurality of ball grooves 422a formed in the second inner joint member 422, respectively.

[0021] The first constant velocity universal joint 41 and the second constant velocity universal joint 42 are fixed type constant velocity universal joints in which relative movement of the first inner joint member 412 in the axial direction of the first outer joint member 411 and relative movement of the second inner joint member 422 in the axial direction of the second outer joint member 421 are restricted. As shown in FIG. 2 , the second kingpin shaft 30 passes through the second inner joint member 422. More specifically, the second kingpin shaft 30 passes through a joint center 420 of the second constant velocity universal joint 42. Here, the joint center 420 is the swing center point when the second inner joint member 422 swings with respect to the second outer joint member 421.

[0022] The intermediate shaft 43 has a first shaft portion 431, one end of which is fixed to the first inner joint member 412, and a second shaft portion 432, one end of which is fixed to the second inner joint member 422, and connects the first inner joint member 412 and the second inner joint member 422 so as to be able to transmit a driving force. The first shaft portion 431 and the second shaft portion 432 are immovable relative to each other but are movable relative to each other in the axial direction. In other words, the intermediate shaft 43 is extendable and contractable in the axial direction and is able to transmit a driving force from the first constant velocity universal joint 41 to the second constant velocity universal joint 42.

[0023] The configuration for connecting the first shaft portion 431 and the second shaft portion 432 so as to be non-rotatable relative to each other but movable relative to each other in the axial direction is not particularly limited. In the example shown in FIG. 2, a portion of the first shaft portion 431 is formed into a cylindrical shape to accommodate the second shaft portion 432, and multiple balls 433 are arranged between the first shaft portion 431 and the second shaft portion 432. The multiple balls 433 are held in a cage (not shown) and roll in ball grooves 431a formed in the first shaft portion 431 and ball grooves 432a formed in the second shaft portion 432. The ball grooves 431a of the first shaft portion 431 are formed linearly along the axial direction on the inner circumferential surface of the first shaft portion 431 facing the second shaft portion 432, and the ball grooves 432a of the second shaft portion 432 are formed linearly along the axial direction on the outer circumferential surface of the second shaft portion 432 facing the inner circumferential surface of the first shaft portion 431.

[0024] In the present embodiment, since the second kingpin shaft 30 passes through the second inner joint member 422 as described above, when the left front wheel 11 and the right front wheel 12 are turned, the amount of movement of the second inner joint member 422 in the circumferential direction around the second kingpin shaft 30 becomes small, and the amount of relative movement in the axial direction between the first shaft portion 431 and the second shaft portion 432 of the intermediate shaft 43 is suppressed.

[0025] The first constant velocity universal joint 41 may be configured as a sliding type constant velocity universal joint that allows relative movement of the first inner joint member in the axial direction of the first outer joint member, instead of a fixed type constant velocity universal joint. Specific examples of the sliding type constant velocity universal joint include a tripod type constant velocity universal joint and the first constant velocity universal joint in the second embodiment described below. When the first outer joint member is a sliding type constant velocity universal joint, the intermediate shaft 43 does not need to be configured to be extendable and contractible in the axial direction.

[0026] 3, the electric motor 21 has a stator 21A in which a multi-phase armature winding 212 is wound around a stator core 211, a rotor 21B in which a plurality of magnets 214 are fixed to a rotor core 213, and a motor case 215 that houses the stator 21A and the rotor 21B together with the differential mechanism 22. The rotor core 213 is cylindrical, and the differential mechanism 22 is disposed inside the rotor core 213.

[0027] Motor case 215 integrally includes: a cylindrical portion 215A to which stator core 211 is fixed on the inner surface; a disk-shaped side wall portion 215B in which an insertion hole 215Ba is formed and through which stem portion 411B of first constant velocity universal joint 41 is inserted; a cylindrical support portion 215C that protrudes from side wall portion 215B in the axial direction toward the outside of motor case 215; and a flange portion 215D for attachment to first attachment member 25. Flange portion 215D is fixed to first attachment member 25 with a plurality of bolts 61.

[0028] The differential mechanism 22 has a differential case 221 as an input rotating member that rotates integrally with the rotor core 213, a first planetary gear 222 and a second planetary gear 223 that are held in the differential case 221 and meshed with each other, a first side gear 224 as a first output rotating member that meshes with the first planetary gear 222, and a second side gear 225 as a second output rotating member that meshes with the second planetary gear 223.

[0029] The differential case 221 is fixed to the rotor core 213 by a plurality of bolts 62, and receives the driving force generated by the electric motor 21. The first side gear 224 and the second side gear 225 are rotatable relative to each other within the differential case 221 due to the rotation of the first planetary gear 222 and the second planetary gear 223. The differential mechanism 22 distributes the driving force input to the differential case 221 to the first side gear 224 and the second side gear 225 while allowing differential movement. One axial end of the differential case 221 is rotatably supported by a ball bearing 631 relative to the first mounting member 25, and the other axial end is rotatably supported by a ball bearing 632 relative to the motor case 215.

[0030] The first outer joint member 411 has a spline fitting portion 411Ba provided at the tip of the stem portion 411B that is spline-fitted to the second side gear 225 so as to be unable to rotate relative to the second side gear 225, and rotates integrally with the second side gear 225. The stem portion 411B of the first outer joint member 411 is supported by a radial bearing 64 that is arranged between the stem portion 411B and the differential case 221, and the cup portion 411A is supported by a ball bearing 65 that is arranged between the cup portion 411A and the support portion 215C of the motor case 215. A seal member 66 is arranged alongside the ball bearing 65 between the cup portion 411A and the support portion 215C of the motor case 215.

[0031] The connecting shaft 24 integrally includes a splined engagement portion 24a that is splined to the first side gear 224 so as not to rotate relative to the first side gear 224, and a gear portion 24b that meshes with a gear portion 238a formed on a first hub shaft 238 of the first hub unit 23, which will be described later. The connecting shaft 24 is rotatably supported by a radial bearing 671 that is arranged between the connecting shaft 24 and the differential case 221, and a radial bearing 672 that is arranged in a support hole 231a that is formed in the first outer ring 231 of the first hub unit 23. The connecting shaft 24 transmits the rotation of the first side gear 224 to the first hub shaft 238.

[0032] The first hub unit 23 rotatably supports the left front wheel 11 and transmits the driving force distributed to the first side gear 224 to the left front wheel 11 . The first hub unit 23 has a first outer ring 231 fixed to the first mounting member 25 by a plurality of bolts 68, a first hub ring 232 to which the wheel 111 of the left front wheel 11 is attached, a first inner ring 233 fitted to one axial end of the first hub ring 232, a sealing member 234 and a plurality of rolling elements 235 arranged between the first outer ring 231 and the first hub ring 232, a plurality of rolling elements 236 arranged between the first outer ring 231 and the first inner ring 233, a retainer 237 that holds the plurality of rolling elements 235, 236, a first hub shaft 238 that rotates integrally with the first hub ring 232, and a hub nut 239 that prevents the first hub shaft 238 from coming off the first hub ring 232.

[0033] The first hub shaft 238 has a gear portion 238a that meshes with the gear portion 24b of the connecting shaft 24, and a boss portion 238b that is supported on the first mounting member 25 by a radial bearing 69. The pitch circle diameter of the gear portion 238a of the first hub shaft 238 is larger than the pitch circle diameter of the gear portion 24b of the connecting shaft 24, and the rotation of the first side gear 224 is reduced in speed and transmitted to the first hub wheel 232 via the connecting shaft 24. The first hub wheel 232 has a wheel mounting flange 232A, and the wheel 111 of the left front wheel 11 and the brake rotor 600 are fixed to the first hub wheel 232 by hub bolts 230 that are press-fitted into fitting holes 232Aa formed in the wheel mounting flange 232A.

[0034] The intermediate shaft 43 connects the second side gear 225 of the differential mechanism 22 and the second hub unit 31 of the second drive part 3, and transmits the driving force distributed to the second side gear 225 to the second hub unit 31. The second hub unit 31 rotatably supports the right front wheel 12, and transmits the driving force distributed to the second side gear 225, which is transmitted by the intermediate shaft 43, to the right front wheel 12.

[0035] The second hub unit 31 is configured in the same manner as the first hub unit 23 of the first drive unit 2, and includes a second outer ring 311 fixed to the second mounting member 32 by a plurality of bolts 71, a second hub ring 312 to which the wheel 121 of the right front wheel 12 is attached, a second inner ring 313 fitted to one axial end of the second hub ring 312, a sealing member 314 and a plurality of rolling elements 315 arranged between the second outer ring 311 and the second hub ring 312, a plurality of rolling elements 316 arranged between the second outer ring 311 and the second inner ring 313, a retainer 317 that holds the plurality of rolling elements 315, 316, a second hub shaft 318 that rotates integrally with the second hub ring 312, and a hub nut 319 that prevents the second hub shaft 318 from coming off the second hub ring 312. The second hub shaft 318 has a gear portion 318 a and a boss portion 318 b that is supported on the second mounting member 32 by a radial bearing 72 .

[0036] The stem portion 421B of the second outer joint member 421 has a gear portion 421Ba that meshes with the gear portion 318a of the second hub shaft 318. The cup portion 421A of the second outer joint member 421 is supported by a ball bearing 73 arranged between the cup portion 421A and the second mounting member 32, and the stem portion 421B is supported by a radial bearing 74 arranged in a support hole 311a formed in the second outer ring 311 of the second hub unit 31. A seal member 75 is arranged alongside the ball bearing 73 between the cup portion 421A and the second mounting member 32.

[0037] The pitch circle diameter of gear portion 318a of second hub shaft 318 is larger than the pitch circle diameter of gear portion 421Ba of stem portion 421B, and rotation of second side gear 225 is reduced via intermediate shaft 43 and transmitted to second hub wheel 312. Second hub wheel 312 has a wheel mounting flange 312A, and the wheel 121 of right front wheel 12 and brake rotor 700 are fixed to second hub wheel 312 by hub bolts 310 press-fitted into fitting holes 312Aa formed in wheel mounting flange 312A.

[0038] (Operation of vehicle drive device 1) In the vehicle drive device 1 configured as described above, the driving force generated by the electric motor 21 is distributed by the differential mechanism 22 and output from the first side gear 224 and the second side gear 225, and the driving force output from the first side gear 224 is transmitted to the left front wheel 11 via the connecting shaft 24 and the first hub unit 23, while the driving force output from the second side gear 225 is transmitted to the right front wheel 12 via the intermediate shaft 43 and the second hub unit 31. Furthermore, when the left front wheel 11 and the right front wheel 12 are steered to cause the vehicle 10 to turn, the first side gear 224 and the second side gear 225 rotate differentially, the first inner joint member 412 of the first constant velocity universal joint 41 tilts relative to the first outer joint member 411 at a joint angle corresponding to the steering angle, and the second inner joint member 422 of the second constant velocity universal joint 42 tilts relative to the second outer joint member 421 at a joint angle corresponding to the steering angle, and in this state, a driving force is transmitted to the second drive unit 3 side by the drive shaft 4. As a result, the left front wheel 11 and the right front wheel 12 are driven to rotate by the single electric motor 21 and the single drive shaft 4.

[0039] (Effects of the first embodiment) According to the first embodiment described above, the first drive unit 2 and the second drive unit 3 are disposed at the left and right ends of the vehicle 10, and only the drive shaft 4 is disposed in the center of the vehicle width, which allows for a low floor and makes it easy to ensure a large passenger compartment or luggage space. Furthermore, since the left front wheel 11 and the right front wheel 12 can be driven and rotated by a single electric motor 21 and a single drive shaft 4, the weight and cost of the vehicle 10 can be reduced.

[0040] 2 shows a case where the connecting shaft 24 and the stem portion 411B of the first outer joint member 411 are disposed vertically below the first hub shaft 238, and the stem portion 421B of the second outer joint member 421 is disposed vertically below the second hub shaft 318, but these arrangements are not limited to those illustrated in FIG. 2 , and various arrangements can be adopted depending on the application and required specifications of the vehicle 10. For example, in order to increase the ground clearance, the rotational axes of the connecting shaft 24 and the first outer joint member 411 may be made higher than the rotational axis of the first hub shaft 238, and the rotational axis of the second outer joint member 421 may be made higher than the rotational axis of the second hub shaft 318. In addition, the rotational axes of the connecting shaft 24 and the first outer joint member 411 and the rotational axis of the first hub shaft 238 may be offset in the longitudinal direction of the vehicle, and the rotational axis of the second outer joint member 421 and the rotational axis of the second hub shaft 318 may be offset in the longitudinal direction of the vehicle.

[0041] [Second embodiment] Fig. 5 is a cross-sectional view showing the configuration of a vehicle drive device 1A according to a second embodiment of the present invention, together with its peripheral members. The vehicle drive device 1A has a first drive unit 2 and a second drive unit 3 configured similarly to those in the first embodiment, and a drive shaft 4A between the first drive unit 2 and the second drive unit 3. Fig. 5 shows a horizontal cross section of the vehicle drive device 1A as viewed from above in the vertical direction.

[0042] In the above first embodiment, a case has been described in which the left front wheel 11 is driven by the first drive unit 2 and the right front wheel 12 is driven by the second drive unit 3. In the second embodiment, a case will be described in which the left rear wheel 13 is driven by the first drive unit 2 and the right rear wheel 14 is driven by the second drive unit 3. That is, in this embodiment, the left rear wheel 13 corresponds to the first drive wheel and the right rear wheel 14 corresponds to the second drive wheel. In FIG. 5, components and the like that have the same functions as those described in the first embodiment are designated by the same reference numerals as those in FIG. 2, and duplicated description will be omitted.

[0043] In this embodiment, the first mounting member 25 of the first drive unit 2 and the second mounting member 32 of the second drive unit 3 are suspended by a rear-wheel suspension 8. The suspension 8 has a torsion beam 81, arm bushings 82 and 83, shock absorbers 84 and 85, and coil springs 86 and 87. Part of the first mounting member 25 of the first drive unit 2 forms a left trailing arm 254 and a spring mount 255. Part of the second mounting member 32 of the second drive unit 3 forms a right trailing arm 324 and a spring mount 325.

[0044] Arm bushings 82, 83 are provided at the tip ends of the trailing arms 254, 324, respectively. A torsion beam 81 connects the left trailing arm 254 and the right trailing arm 324. The torsion beam 81 may be integral with the trailing arms 254, 324. Alternatively, the trailing arms 254, 324 may be separate from the first mounting member 25 and the second mounting member 32.

[0045] The left shock absorber 84 and coil spring 86 are disposed between the vehicle body and spring mount 255. The right shock absorber 85 and coil spring 87 are disposed between the vehicle body and spring mount 325. Note that the spring mount 255 may be separate from the first mounting member 25, and the spring mount 325 may be separate from the second mounting member 32.

[0046] The drive shaft 4A has a first constant velocity universal joint 41A which is a sliding type constant velocity universal joint, a second constant velocity universal joint 42A which is a fixed type constant velocity universal joint, and an intermediate shaft 43A between the first constant velocity universal joint 41A and the second constant velocity universal joint 42A. The second constant velocity universal joint 42A is configured in the same manner as the second constant velocity universal joint 42 according to the first embodiment, and has a second outer joint member 421, a second inner joint member 422, a plurality of balls 423, and a cage 424.

[0047] The first constant velocity universal joint 41A has a first outer joint member 411, a first inner joint member 412, a plurality of balls 413, and a cage 414, similar to the first constant velocity universal joint 41 according to the first embodiment, but a plurality of ball grooves 411a in which the plurality of balls 413 roll respectively are formed linearly extending in the axial direction of the first outer joint member 411, thereby enabling relative movement of the first inner joint member 412 in the axial direction of the first outer joint member 411. The first outer joint member 411 has a cup portion 411A and a stem portion 411B, and the stem portion 411B is spline-fitted to the second side gear 225 so as not to rotate relative to it.

[0048] The intermediate shaft 43A has one axial end to which the first inner joint member 412 of the first constant velocity universal joint 41A is fixed, and the other axial end to which the second inner joint member 422 of the second constant velocity universal joint 42A is fixed. In the first embodiment, the intermediate shaft 43 is extendable and contractible in the axial direction, but in the present embodiment, the axial length of the intermediate shaft 43A is fixed. Note that the first constant velocity universal joint 41A and the second constant velocity universal joint 42A may be interchanged, and the first constant velocity universal joint 41A may be a fixed type constant velocity universal joint, and the second constant velocity universal joint 42A may be a sliding type constant velocity universal joint.

[0049] The configurations of the electric motor 21, differential mechanism 22, first hub unit 23, and second hub unit 31 are the same as those in the first embodiment. As in the first embodiment, the electric motor 21 is supplied with AC current, which is obtained by switching DC current supplied from the battery 15 by the inverter 16 in response to a PWM signal output by the control device 17. A wheel 131 of the left rear wheel 13 is attached to a first hub wheel 232 of the first hub unit 23 with a plurality of hub bolts 230. A wheel 141 of the right rear wheel 14 is attached to a second hub wheel 312 of the second hub unit 31 with a plurality of hub bolts 310.

[0050] The second embodiment also provides the same effects as the first embodiment. Note that the vehicle may be a four-wheel drive vehicle in which the left front wheel 11 and the right front wheel 12 are driven by the front-wheel vehicle drive system 1 and the left rear wheel 13 and the right rear wheel 14 are driven by the rear-wheel vehicle drive system 1A. Alternatively, the vehicle may be a four-wheel drive vehicle in which the left front wheel 11 and the right front wheel 12 are driven by an internal combustion engine and the left rear wheel 13 and the right rear wheel 14 are driven by the vehicle drive system 1A.

[0051] In the example shown in FIG. 5, the connecting shaft 24 and the first outer joint member 411 are arranged side by side with the first hub shaft 238 in the horizontal direction, and the second outer joint member 421 is arranged side by side with the second hub shaft 318 in the horizontal direction. However, the present invention is not limited to this. The connecting shaft 24, the first outer joint member 411, and the first hub shaft 238 may be arranged side by side in the vertical direction, and the second outer joint member 421 and the second hub shaft 318 may be arranged side by side in the vertical direction.

[0052] (Addendum) The present invention has been described above based on the first and second embodiments, but these embodiments do not limit the scope of the invention claimed in the claims. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented by omitting some components or adding or substituting components within the scope of its spirit. [Explanation of symbols]

[0053] 1, 1A...Vehicle drive device 11...Front left wheel (first drive wheel) 12...Right front wheel (second drive wheel) 13...Left rear wheel (first drive wheel) 14...Right rear wheel (second drive wheel) 21...Electric motor 22…Differential mechanism 221...Differential case (input rotating member) 224...First side gear (first output rotating member) 225...Second side gear (second output rotating member) 23...First hub unit (first bearing mechanism) 232...First hub wheel 24...Second hub unit (second bearing mechanism) 25...First mounting member 30...Second kingpin axis 312...Second hub wheel 32...Second mounting member 4,4A...Drive shaft 411...First outer joint member 412...First inner joint member 421...Second outer joint member 422...Second inner joint member 43, 43A...Intermediate shaft

Claims

1. A vehicle drive device mounted on a vehicle having first drive wheels and second drive wheels on left and right sides in a vehicle width direction, the vehicle drive device driving the first drive wheels and the second drive wheels, an electric motor that generates a driving force for driving the first driving wheel and the second driving wheel; a differential mechanism including an input rotary member to which a driving force generated by the electric motor is input, and a first output rotary member and a second output rotary member which are rotatable relative to each other, and which distributes the driving force input to the input rotary member to the first output rotary member and the second output rotary member while allowing differential movement; a first bearing mechanism that rotatably supports the first drive wheel and transmits the driving force distributed to the first output rotary member to the first drive wheel; a second bearing mechanism that rotatably supports the second drive wheel and transmits the driving force distributed to the second output rotary member to the second drive wheel; a first mounting member to which the electric motor, the differential mechanism, and the first bearing mechanism are attached; a second mounting member to which the second bearing mechanism is attached; and a drive shaft that connects the second output rotating member and the second bearing mechanism and transmits the driving force distributed to the second output rotating member to the second bearing mechanism; A vehicle drive device comprising:

2. the first bearing mechanism has a first hub wheel to which the first drive wheel is attached, the second bearing mechanism has a second hub wheel to which the second drive wheel is attached, The rotation of the first output rotary member is reduced and transmitted to the first hub wheel, The rotation of the second output rotary member is decelerated and transmitted to the second hub wheel. The vehicle drive system according to claim 1 .

3. The drive shaft comprises a first constant velocity universal joint having a first outer joint member rotatably supported on the first mounting member and a first inner joint member pivotable relative to the first outer joint member, a second constant velocity universal joint having a second outer joint member rotatably supported on the second mounting member and a second inner joint member pivotable relative to the second outer joint member, and an intermediate shaft connecting the first inner joint member and the second inner joint member so as to transmit a driving force. The vehicle drive system according to claim 2 .

4. the first constant velocity universal joint and the second constant velocity universal joint are fixed type constant velocity universal joints in which relative movement of the first inner joint member in the axial direction of the first outer joint member and relative movement of the second inner joint member in the axial direction of the second outer joint member are restricted, the intermediate shaft has a first shaft portion fixed to the first inner joint member and a second shaft portion fixed to the second inner joint member, and the first shaft portion and the second shaft portion are non-rotatable relative to each other but are movable relative to each other in the axial direction. The vehicle drive system according to claim 3 .

5. the first constant velocity universal joint is a sliding type constant velocity universal joint that allows relative movement of the first inner joint member in the axial direction of the first outer joint member, the second constant velocity universal joint is a fixed type constant velocity universal joint in which relative movement of the second inner joint member in the axial direction of the second outer joint member is restricted. The vehicle drive system according to claim 3 .

6. the first drive wheel and the second drive wheel are steered wheels of the vehicle, a second kingpin axis, which is a steering center line of the second drive wheel, passes through the second inner joint member; 6. The vehicle drive device according to claim 4 or 5.

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