Vehicle drive device

Abstract

To provide a vehicle drive device capable of reducing vibration of a rotor shaft, capable of reducing manufacturing cost, and easy to assemble.SOLUTION: A vehicle drive device 100 has rotary electrical machinery 1, a rotor shaft 2, a first gear 3, a rotation sensor 7, and a case 9. The rotor shaft 2 integrally rotates with a rotor 12 of the rotary electrical machinery 1. The first gear 3 is integrally formed in the rotor shaft 2. The rotation sensor 7 detects rotation of the rotor 12. The rotor shaft 2 is rotatably supported with respect to the case 9 by a first bearing B1, a second bearing B2, and a third bearing B3. The third bearing B3 is arranged between the rotor 12 and the first gear 3. The rotation sensor 7 has a sensor stator 71 arranged between the rotor 12 and the third bearing B3. An outer diameter of the third bearing B3 is smaller than an inner diameter of the sensor stator 71. The inner diameter of the third bearing B3 is larger than an outer diameter 3a of the first gear 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle drive device including a rotating electrical machine having a rotor, an output member drivingly connected to a wheel, a rotor shaft rotating integrally with the rotor, and a power transmission mechanism.

Background Art

[0002] An example of such a vehicle drive device is disclosed in Patent Document 1 below. In the following description of the background art, the reference numerals and names in Patent Document 1 are cited in parentheses.

[0003] The vehicle drive device (integrated motor drive power assembly) of Patent Document 1 includes a rotating electrical machine (motor) having a rotor (17), a rotor shaft (main shaft 18) rotating integrally with the rotor (17) of the rotating electrical machine (motor), a first gear (9), a second gear (14) meshing with the first gear (9), and a case (3, 7) housing these components. The first gear (9) is fitted to the outer peripheral surface of the rotor shaft (main shaft 18) and rotates integrally with the rotor shaft (main shaft 18). This rotor shaft (main shaft 18) is supported by a first bearing (right end bearing 20) and a second bearing (left end bearing 8) disposed at both ends thereof, and a third bearing (intermediate bearing 15). The third bearing (intermediate bearing 15) is disposed between the rotor (17) and the first gear (9).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in a situation where the rotor shaft rotates, loads such as centrifugal force act on the rotor, and loads such as meshing reaction forces of the gears act on the first gear. In the configuration described in Patent Document 1, since the rotor shaft and the first gear are constituted by separate members, the loads generated on each of the rotor and the first gear cause a deviation between the rotation axis of the rotor shaft and the rotation axis of the first gear. Such an axis deviation has been a factor increasing the vibration at the fitting portion between the rotor shaft and the first gear and at the meshing portion of the first gear. Also, since a fitting portion for fitting the rotor shaft and the first gear is required, it has also been a factor increasing the processing cost of each part. However, if the rotor shaft and the first gear are not constituted by separate members, assembly may become difficult in relation to the case and members arranged around it.

[0006] Therefore, it is desired to realize a vehicle drive device capable of reducing the vibration of the rotor shaft and the manufacturing cost and facilitating assembly.

Means for Solving the Problems

[0007] In view of the above, the characteristic configuration of the vehicle drive device includes a rotating electric machine having a rotor, an output member drivingly connected to a wheel, a rotor shaft fixed to the rotor so as to rotate integrally with the rotor, a first gear integrally formed on the rotor shaft, a second gear meshing with the first gear, a power transmission mechanism for drivingly connecting the second gear and the output member, a rotation sensor for detecting the rotation of the rotor, and a case for housing the rotating electric machine, the rotor shaft, the power transmission mechanism, and the rotation sensor. The direction along the axis of the rotor shaft is defined as the axial direction, the direction orthogonal to the axis is defined as the radial direction, one side in the axial direction is defined as the first axial side, and the other side in the axial direction is defined as the second axial side. The first gear is disposed on the second axial side with respect to the rotor. The rotor shaft is rotatably supported by the case at three positions in the axial direction by a first bearing, a second bearing, and a third bearing. The first bearing is disposed on the first axial side with respect to the rotor. The second bearing is disposed on the second axial side with respect to the first gear. The third bearing is disposed between the rotor and the first gear in the axial direction. The case includes an intermediate support portion for supporting the third bearing from the outside in the radial direction. The rotation sensor includes a sensor stator disposed between the rotor and the third bearing in the axial direction and supported by the intermediate support portion. The outer diameter of the third bearing is smaller than the inner diameter of the sensor stator, and the inner diameter of the third bearing is larger than the outer diameter of the first gear.

[0008] According to this characteristic configuration, since the first gear is integrally formed on the rotor shaft, compared with the case where the rotor shaft and the first gear are separated, the axial deviation between the rotor shaft and the first gear can be reduced, and the occurrence of vibration (vibration caused by wobbling) due to such axial deviation can be suppressed. Further, according to this configuration, since the fitting portion between the rotor shaft and the first gear that is required when the rotor shaft and the first gear are separated can be made unnecessary, it is easy to reduce the manufacturing cost. Furthermore, according to this configuration, since the third bearing can pass axially through the radially outer side of the first gear and the third bearing can pass axially through the radially inner side of the sensor stator, the third bearing can be assembled to the rotor shaft from the second side in the axial direction, and the third bearing can be inserted axially from the first side into the case to which the sensor stator is attached. Therefore, the assembly of the third bearing to both the rotor shaft and the case becomes easy, and it is easy to facilitate the assembly work of the vehicle drive device. From the above, it is possible to reduce the vibration of the rotor shaft and the manufacturing cost, and a vehicle drive device that is easy to assemble can be realized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the vehicle drive device 100 according to the embodiment will be described with reference to the drawings. As shown in FIGS. 1 and 2, the vehicle drive device 100 includes a rotating electric machine 1 having a rotor 12, an output member 4 drivingly connected to a wheel W, a rotor shaft 2, a power transmission mechanism 5, a rotation sensor 7, and a case 9. The rotor shaft 2 and the power transmission mechanism 5 drivingly connect the rotor 12 and the output member 4. The rotation sensor 7 detects the rotation of the rotor 12. The case 9 houses the rotating electric machine 1, the rotor shaft 2, the power transmission mechanism 5, and the rotation sensor 7.

[0011] Here, in the present application, "drivingly connected" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force, including a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or with speed change, for example, shafts, gear mechanisms, belts, chains, etc. Note that the transmission members may include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices.

[0012] The rotating electric machine 1 functions as a driving force source for the wheel W. The rotating electric machine 1 has a function as a motor (electric motor) that generates power upon receiving power supply, and a function as a generator (electric generator) that generates power upon receiving power supply. Specifically, the rotating electric machine 1 is electrically connected to a power storage device (not shown) such as a battery or a capacitor. Then, the rotating electric machine 1 performs power running by the power stored in the power storage device to generate a driving force. Further, the rotating electric machine 1 generates electricity by the driving force transmitted from the wheel W side to charge the power storage device.

[0013] The rotor shaft 2 includes a shaft member connected so as to rotate integrally with the rotor 12. The rotor shaft 2 is fixed to the rotor 12. Further, the rotor shaft 2 has a first gear 3. The first gear 3 is integrally formed on the rotor shaft 2. In the present embodiment, the first gear 3 is formed of the same member as the rotor shaft 2. Note that "the first gear 3 is integrally formed on the rotor shaft 2" includes forming a separate member inseparably by welding or the like.

[0014] The power transmission mechanism 5 drivingly connects the first gear 3 and the output member 4. The power transmission mechanism 5 includes a second gear 511 that meshes with the first gear 3. The power transmission mechanism 5 drivingly connects the second gear 511 and the output member 4. In the present embodiment, the power transmission mechanism 5 includes a counter gear mechanism 51 and a differential gear mechanism 52.

[0015] In the present embodiment, the rotor shaft 2 is disposed on a first axis X1 that is the rotational axis of the rotary electric machine 1 (rotor 12). Further, the counter gear mechanism 51 is disposed on a second axis X2 that is different from the first axis X1. Further, the output member 4 and the differential gear mechanism 52 are disposed on a third axis X3 that is different from the first axis X1 and the second axis X2. In this example, the axes X1 to X3 are arranged parallel to each other.

[0016] In the following description, the direction along the axis X1 is defined as the "axial direction L" of the vehicle drive device 100. Further, the direction orthogonal to the rotational axis of the rotating member such as the rotor 12 is defined as the "radial direction R" with respect to each rotational axis. When it is not necessary to distinguish which rotational axis is the reference or when it is clear which rotational axis is the reference, it may be simply referred to as the "radial direction R". Then, one side in the axial direction L is defined as the first axial side L1. The other side in the axial direction L is defined as the second axial side L2.

[0017] The case 9 houses the rotary electric machine 1, the rotor shaft 2, and the power transmission mechanism 5. In the present embodiment, the case 9 also houses a pair of output members 4.

[0018] As shown in FIG. 1, in the present embodiment, the case 9 has a first housing portion A1, a second housing portion A2, and a third housing portion A3 inside. The first housing portion A1 includes a space in which the rotary electric machine 1 and the rotor shaft 2 are housed. The second housing portion A2 includes a space in which the first gear 3 and the counter gear mechanism 51 are housed. The third housing portion A3 includes a space in which a pair of output members 4 and the differential gear mechanism 52 are housed.

[0019] In this embodiment, the case 9 includes a partition wall portion 91, a first peripheral wall portion 92a, a first side wall portion 92b, a second peripheral wall portion 93a, a second side wall portion 93b, a third peripheral wall portion 94a, a third side wall portion 94b, and a fourth side wall portion 94c.

[0020] The partition wall portion 91 is formed so as to partition the first accommodation portion A1 and the second accommodation portion A2. In this embodiment, the partition wall portion 91 is formed to extend in the radial direction R. That is, the partition wall portion 91 partitions the first accommodation portion A1 and the second accommodation portion A2 in the axial direction L.

[0021] The first peripheral wall portion 92a is formed to cover the outside of the rotating electric machine 1 in the radial direction R. The first side wall portion 92b is formed to cover the first side L1 in the axial direction of the rotating electric machine 1. In this embodiment, the first peripheral wall portion 92a is formed in a cylindrical shape with an opening on the first side L1 in the axial direction. And the opening on the first side L1 in the axial direction of the first peripheral wall portion 92a is blocked by the first side wall portion 92b. On the other hand, the partition wall portion 91 is integrally provided at a portion on the second side L2 in the axial direction with respect to the rotating electric machine 1 in the first peripheral wall portion 92a.

[0022] The second peripheral wall portion 93a is formed to cover the outside of the first gear 3 and the counter gear mechanism 51 in the radial direction R. The second side wall portion 93b is formed to cover the second side L2 in the axial direction of the first gear 3 and the counter gear mechanism 51. In this embodiment, the second peripheral wall portion 93a is formed in a cylindrical shape with an opening on the second side L2 in the axial direction. And the opening on the second side L2 in the axial direction of the second peripheral wall portion 93a is blocked by the second side wall portion 93b. On the other hand, the partition wall portion 91 is integrally provided at a portion on the first side L1 in the axial direction with respect to the first gear 3 in the second peripheral wall portion 93a.

[0023] The third circumferential wall portion 94a is formed so as to cover the outside in the radial direction R of the pair of output members 4 and the differential gear mechanism 52. The third side wall portion 94b is formed so as to cover the first axial side L1 of the differential gear mechanism 52. The fourth side wall portion 94c is formed so as to cover the second axial side L2 of the differential gear mechanism 52. In the present embodiment, the third circumferential wall portion 94a is formed in a cylindrical shape with the second axial side L2 being open. And the opening on the second axial side L2 of the third circumferential wall portion 94a is blocked by the fourth side wall portion 94c. On the other hand, the third side wall portion 94b is integrally provided at a portion on the first axial side L1 of the third circumferential wall portion 94a with respect to the differential gear mechanism 52.

[0024] In the present embodiment, the first circumferential wall portion 92a is formed so as to extend from the partition portion 91 to the first axial side L1. And the second circumferential wall portion 93a is formed so as to extend from the partition portion 91 to the second axial side L2. In the example shown in FIG. 1, the partition portion 91, the first circumferential wall portion 92a, the second circumferential wall portion 93a, the third circumferential wall portion 94a, and the third side wall portion 94b are integrally formed to constitute the first case portion 9A. And the second case portion 9B provided with the first side wall portion 92b is joined to the first case portion 9A from the first axial side L1. Further, the third case portion 9C provided with the second side wall portion 93b and the fourth side wall portion 94c is joined to the first case portion 9A from the second axial side L2.

[0025] In the present embodiment, the first accommodation portion A1 is formed by the partition portion 91, the first circumferential wall portion 92a, and the first side wall portion 92b. That is, the space surrounded by the partition portion 91, the first circumferential wall portion 92a, and the first side wall portion 92b inside the case 9 is formed as the first accommodation portion A1.

[0026] In addition, in the present embodiment, the second housing portion A2 is formed by the partition wall portion 91, the second peripheral wall portion 93a, and the second side wall portion 93b. That is, the space surrounded by the partition wall portion 91, the second peripheral wall portion 93a, and the second side wall portion 93b inside the case 9 is formed as the second housing portion A2. Further, the third housing portion A3 is formed by the third peripheral wall portion 94a, the third side wall portion 94b, and the fourth side wall portion 94c. That is, the space surrounded by the third peripheral wall portion 94a, the third side wall portion 94b, and the fourth side wall portion 94c inside the case 9 is formed as the third housing portion A3. In the present embodiment, the second housing portion A2 and the third housing portion A3 are formed to communicate with each other.

[0027] The rotating electrical machine 1 further includes a stator 11. The stator 11 includes a cylindrical stator core 111. The stator core 111 is fixed to a non-rotating member. In the present embodiment, the stator core 111 is fixed to the first peripheral wall portion 92a of the case 9 as a non-rotating member. The rotor 12 of the rotating electrical machine 1 includes a cylindrical rotor core 121. The rotor core 121 is rotatably supported with respect to the stator core 111.

[0028] In the present embodiment, the rotating electrical machine 1 is an inner rotor type rotating electrical machine. That is, the stator 11 is disposed on the outer side in the radial direction R with respect to the rotor 12. Therefore, the stator core 111 is disposed on the outer side in the radial direction R with respect to the rotor core 121.

[0029] In addition, in the present embodiment, the rotating electrical machine 1 is of a rotating field type. Therefore, a stator coil is wound around the stator core 111. The stator coil is wound around the stator core 111 so that a pair of coil end portions 112 protruding in the first axial side L1 and the second axial side L2 with respect to the stator core 111 are formed. Further, a permanent magnet 122 is provided on the rotor core 121.

[0030] In this embodiment, the rotor shaft 2 includes a rotor fixing portion 21, a sensor rotor fixing portion 22, a stepped portion 23, a bearing fitting portion 24, and an input shaft portion 25. The rotor fixing portion 21, the sensor rotor fixing portion 22, the stepped portion 23, and the bearing fitting portion 24 are arranged in the described order along the axial direction L from the first axial side L1.

[0031] The rotor 12 is fixed to the rotor fixing portion 21. In this embodiment, the rotor fixing portion 21 is formed in a cylindrical shape having an axis along the axial direction L. In the example shown in FIG. 1, the rotor fixing portion 21 is arranged so as to protrude from the rotor 12 toward the first axial side L1 and the second axial side L2 in the axial direction, respectively.

[0032] As will be described later, the sensor rotor 72 of the rotation sensor 7 is fixed to the sensor rotor fixing portion 22. In this embodiment, the sensor rotor fixing portion 22 is adjacent to the rotor fixing portion 21 on the second axial side L2. And, in the axial direction L, a stepped surface 22b facing the second axial side L2 is formed between the rotor fixing portion 21 and the sensor rotor fixing portion 22 as shown in FIG. 3. The stepped surface 22b is provided so as to protrude outward in the radial direction R from the main body of the rotor shaft 2 (the portion where the rotor fixing portion 21 and the sensor rotor fixing portion 22 are formed).

[0033] The stepped portion 23 has a stepped surface 23a facing the second axial side L2. In this embodiment, the stepped portion 23 is adjacent to the sensor rotor fixing portion 22 on the second axial side L2 and is provided so as to be recessed inward in the radial direction R from the main body of the rotor shaft 2.

[0034] The bearing fitting portion 24 is fitted with the third bearing B3, which will be described later. The outer diameter 24a of the bearing fitting portion 24 is larger than the outer diameter 3a of the first gear 3. The outer diameter 22a of the sensor rotor fixing portion 22 is larger than the outer diameter 24a of the bearing fitting portion 24. In this embodiment, the bearing fitting portion 24 is formed in a stepped shape with the sensor rotor fixing portion 22 with the stepped portion 23 interposed therebetween.

[0035] The input shaft portion 25 is a portion supported by a second bearing B2 described later. In the present embodiment, the input shaft portion 25 is adjacent to the second side L2 in the axial direction with respect to the bearing fitting portion 24, and its outer diameter is smaller than that of the bearing fitting portion 24. Further, in the embodiment, the first gear 3 is formed on the outer peripheral surface of the input shaft portion 25. And the input shaft portion 25 protrudes in the first side L1 and the second side L2 in the axial direction with respect to the first gear 3.

[0036] As shown in FIG. 3, the rotor 12 and the rotor shaft 2 are connected to each other with the inner peripheral surface 12a of the rotor and the outer peripheral surface 2a of the shaft in contact. The inner peripheral surface 12a of the rotor is the inner peripheral surface of the rotor 12. In the present embodiment, the inner peripheral surface 12a of the rotor is the inner peripheral surface of the rotor core 121. The outer peripheral surface 2a of the shaft is the outer peripheral surface of the rotor shaft 2. In the present embodiment, the outer peripheral surface 2a of the shaft is the outer peripheral surface of the rotor fixing portion 21. Also, the rotor 12 and the first gear 3 are arranged at different positions in the axial direction L. And the first gear 3 is arranged on the second side L2 in the axial direction with respect to the rotor 12.

[0037] As shown in FIGS. 1 and 2, the rotor shaft 2 is rotatably supported with respect to the case 9 at three positions in the axial direction L by the first bearing B1, the second bearing B2, and the third bearing B3.

[0038] The first bearing B1 is arranged on the first axial side L1 with respect to the rotor 12. The first bearing B1 rotatably supports the rotor shaft 2. In the present embodiment, the first bearing B1 is arranged to support the outer peripheral surface of the rotor fixing portion 21 of the rotor shaft 2 from the outside in the radial direction R. In the example shown in FIG. 1, the first side wall portion 92b of the case 9 has a first bearing support portion 92c. The first bearing support portion 92c is formed in a cylindrical shape protruding in the second axial side L2 so as to overlap the rotor fixing portion 21 in the radial direction R view along the radial direction R outside the rotor fixing portion 21 in the radial direction R. And the first bearing B1 is arranged between the inner peripheral surface of the first bearing support portion 92c and the outer peripheral surface of the rotor fixing portion 21. Note that, regarding the arrangement of the two elements, "overlapping in a specific direction view" means that when a virtual straight line parallel to the line-of-sight direction is moved in each direction orthogonal to the virtual straight line, there is at least a part of a region where the virtual straight line intersects both of the two elements.

[0039] The second bearing B2 is arranged on the second axial side L2 with respect to the first gear 3. The second bearing B2 rotatably supports the input shaft portion 25 of the rotor shaft 2. In the present embodiment, the second bearing B2 is arranged to support the outer peripheral surface of the input shaft portion 25 from the outside in the radial direction R. In the example shown in FIG. 1, the second side wall portion 93b of the case 9 has a second bearing support portion 93c. The second bearing support portion 93c is formed in a cylindrical shape protruding in the first axial side L1 so as to overlap the input shaft portion 25 in the radial direction R view along the radial direction R outside the input shaft portion 25 in the radial direction R. And the second bearing B2 is arranged between the inner peripheral surface of the second bearing support portion 93c and the outer peripheral surface of the input shaft portion 25.

[0040] The third bearing B3 is disposed between the rotor 12 and the first gear 3 in the axial direction L. The third bearing B3 rotatably supports the rotor shaft 2. In the present embodiment, the third bearing B3 is arranged to support the bearing fitting portion 24 from the outside in the radial direction R. In this example, the third bearing B3 is arranged to support the outer peripheral surface of the bearing fitting portion 24 from the outside in the radial direction R. In this example, the end portion of the third bearing B3 on the first side L1 in the axial direction faces the step surface 23a of the step portion 23. In the present embodiment, the case 9 includes an intermediate support portion 90a that supports the third bearing B3 from the outside in the radial direction R. The third bearing B3 is supported by the intermediate support portion 90a. In this example, as shown in FIG. 1, the intermediate support portion 90a is provided on the first side in the axial direction with respect to the partition portion 91. In the example shown in FIG. 1, the intermediate support portion 90a is integrally formed with the partition portion 91. In other words, the intermediate support portion 90a is integrally formed with the first case portion 9A. The intermediate support portion 90a is formed in a cylindrical shape so as to overlap the bearing fitting portion 24 in a view in the radial direction R along the radial direction R outside the bearing fitting portion 24 of the rotor shaft 2 in the radial direction R.

[0041] The outer diameter of the third bearing B3 is smaller than the inner diameter of the sensor stator 71 described later. Here, the size of the outer diameter of the third bearing B3 refers to the size in a state where the third bearing B3 is attached to the rotor shaft 2. Further, the inner diameter of the third bearing B3 is larger than the outer diameter 3a of the first gear 3. Here, when the third bearing B3 includes a member whose size in the radial direction R can be changed, the size of the inner diameter of the third bearing B3 refers to the inner diameter of a member whose size in the radial direction R cannot be changed. Such bearings include, for example, a bearing having an outer ring B31 whose size in the radial direction R cannot be changed, and rolling elements and a cage whose size in the radial direction R can be freely changed. Specifically, it includes a bearing having a structure in which a circumferential discontinuity is provided in a cage that holds rolling elements, and the cage can be expanded and contracted in diameter by elastic deformation of the cage. For a bearing having such a structure, the inner diameter of the third bearing B3 is the inner diameter of the outer ring whose size in the radial direction R cannot be changed.

[0042] In the example shown in FIG. 1, the length of the axial direction L of the third bearing B3 is longer than the length of the axial direction L of the first bearing B1 and the length of the axial direction L of the second bearing B2. With such a configuration, when the rotor shaft 2 rotates, the magnitude of the inclination of the rotor shaft 2 can be reduced. Further, in the example shown in FIG. 1, the thickness in the radial direction R of the third bearing B3 is smaller than the thickness in the radial direction R of the first bearing B1 and the thickness in the radial direction R of the second bearing B2.

[0043] In this embodiment, as shown in FIG. 3, the third bearing B3 includes an outer ring B31, a plurality of rolling elements B32, and a connecting member B33. The outer ring B31 has conductivity. In the example shown in FIG. 3, the outer ring B31 has an outer peripheral surface B34 that fits into the cylindrical inner peripheral portion of the intermediate support portion 90a. The plurality of rolling elements B32 are accommodated inside the outer ring B31 in the radial direction R. In the example shown in FIG. 3, the plurality of rolling elements B32 are held by a cage B35 disposed inside the outer ring B31 in the radial direction R. The connecting member B33 includes an annular member having conductivity. The connecting member B33 is disposed at different positions in the axial direction L with respect to the plurality of rolling elements B32 and contacts both the outer ring B31 and the outer peripheral surface of the rotor shaft 2. Specifically, the connecting member B33 contacts both the outer ring B31 and the outer peripheral surface B34 of the rotor shaft 2 to such an extent that it has a sealing property against oil and / or an electric current flows between the outer ring B31 and the rotor shaft 2. Here, the oil includes the oil accommodated in the first accommodation portion A1 and the second accommodation portion A2 for lubricating the sliding member and cooling the heat generating component. In the example shown in FIG. 3, the connecting member B33 contacts both the outer ring B31 and the outer peripheral surface of the rotor shaft 2 to such an extent that it has a sealing property against oil and an electric current flows between the outer ring B31 and the rotor shaft 2. The connecting member B33 illustrated in FIG. 1 is disposed on the second side L2 in the axial direction with respect to the plurality of rolling elements B32. And the connecting member B33 fits onto the outer peripheral surface of the bearing fitting portion 24 and contacts the inner peripheral surface of the outer ring B31. Therefore, the current generated in the rotor 12 flows into the connecting member B33. Thus, the possibility of electric corrosion occurring on the rolling elements B32 and the raceway surface of the third bearing B3 can be reduced by the current generated in the rotor 12 flowing through the plurality of rolling elements B32. In addition, the connecting member B33 can restrict the plurality of rolling elements B32 and the oil present in the first accommodation portion A1 from flowing into the second accommodation portion A2.

[0044] Further, the third bearing B3 may include an inner ring (not shown) having conductivity. In this case, it is preferable that the connecting member B33 contacts both the outer ring B31 and the inner ring. Here, the connecting member B33 contacts both the outer ring B31 and the inner ring to such an extent that it has a sealing property against oil and / or an electric current flows between the outer ring B31 and the inner ring.

[0045] In this embodiment, the third bearing B3 includes a shell-type needle roller bearing having a plurality of needle rollers as a plurality of rolling elements B32. In this case, the shell-type needle roller bearing of this embodiment does not include an inner ring. Further, the third bearing B3 of this embodiment includes a cage B35 that holds a plurality of needle rollers. The cage B35 of this embodiment holds the intervals between the plurality of needle rollers. The plurality of needle rollers are accommodated inside the outer ring B31 in the radial direction R. In the example shown in FIG. 3, the outer ring B31 has an outer peripheral surface B34 that fits into the cylindrical inner peripheral portion of the intermediate support portion 90a. Further, as shown in FIG. 3, the outer ring B31 may include an outer peripheral member B36 that extends in the axial direction L and a pair of edge portions B37 that project radially inward from both ends of the outer peripheral member B36 in the axial direction L. And the plurality of needle rollers are accommodated between the pair of edge portions B37 in the axial direction L. In this case, the third bearing B3 may include a connecting member B33. In the example shown in FIG. 3, the connecting member B33 is disposed between the plurality of rolling elements B32 and the edge portion B37 in the axial direction L. Therefore, when assembling the connecting member B33 to the rotor shaft 2, the connecting member B33 is assembled to the rotor shaft 2 together with the outer ring B31 and the rolling elements B32, so that the assembly of the connecting member B33 to the rotor shaft 2 becomes easy.

[0046] As shown in FIG. 1, the counter gear mechanism 51 includes a second gear 511 that meshes with the first gear 3, a third gear 512 that rotates integrally with the second gear 511, and a connecting shaft 513 that connects the second gear 511 and the third gear 512.

[0047] The second gear 511 and the third gear 512 are connected so as to rotate integrally via the connecting shaft 513. In the example shown in FIG. 1, the second gear 511 is connected to the connecting shaft 513 by spline engagement. And the third gear 512 is formed integrally with the connecting shaft 513. Further, in the example shown in FIG. 1, the third gear 512 is formed to have a smaller diameter than the second gear 511. And the third gear 512 is arranged such that the axial L arrangement region of the third gear 512 overlaps with the axial L arrangement region of the second bearing B2.

[0048] The connecting shaft 513 is formed to extend along the second axis X2. In the present embodiment, the connecting shaft 513 is rotatably supported with respect to the case 9 by the first counter bearing B4 and the second counter bearing B5.

[0049] In the present embodiment, the first counter bearing B4 is arranged on the first axial side L1 with respect to the second gear 511. In the example shown in FIG. 1, the first counter bearing B4 is arranged inside the radial direction R with reference to the second axis X2 with respect to the second gear 511.

[0050] Also, in the present embodiment, the first counter bearing B4 is arranged so as to support the outer peripheral surface of the connecting shaft 513 from the outside in the radial direction R. In the example shown in FIG. 1, the partition wall portion 91 of the case 9 has a first counter bearing support portion 91a. The first counter bearing support portion 91a is formed in a cylindrical shape that protrudes in the second axial side L2 inside the radial direction R from the second gear 511. And the first counter bearing B4 is arranged between the inner peripheral surface of the first counter bearing support portion 91a and the outer peripheral surface of the connecting shaft 513.

[0051] In the present embodiment, the second counter bearing B5 is arranged on the second axial side L2 with respect to the third gear 512.

[0052] In addition, in the present embodiment, the second counter bearing B5 is arranged to support the outer peripheral surface of the connecting shaft 513 from the outer side in the radial direction R. In the example shown in FIG. 1, the second side wall portion 93b of the case 9 has a second counter bearing support portion 93d. The second counter bearing support portion 93d is formed in a cylindrical shape that protrudes in the second axial side L2 so as to be separated from the third gear 512. In other words, the second counter bearing support portion 93d is formed so as to protrude in the second axial side L2 more than the portion other than the second counter bearing support portion 93d in the second side wall portion 93b. As a result, the second counter bearing support portion 93d is formed in a cylindrical shape that overlaps the connecting shaft 513 in a view along the radial direction R on the outer side of the connecting shaft 513 in the radial direction R. And the second counter bearing B5 is arranged between the inner peripheral surface of the second counter bearing support portion 93d and the outer peripheral surface of the connecting shaft 513. Thus, in the present embodiment, the second counter bearing B5 is arranged on the second axial side L2 with respect to the second bearing B2.

[0053] The differential gear mechanism 52 includes a fourth gear 521 that meshes with the third gear 512. And the differential gear mechanism 52 distributes the rotation of the fourth gear 521 to the pair of output members 4.

[0054] In the present embodiment, the differential gear mechanism 52 further includes a differential case 522, a pair of pinion gears 523, and a pair of side gears 524. Here, both the pair of pinion gears 523 and the pair of side gears 524 are bevel gears.

[0055] The differential case 522 is a hollow member that houses the pair of pinion gears 523 and the pair of side gears 524. The differential case 522 is connected so as to rotate integrally with the fourth gear 521.

[0056] A pair of pinion gears 523 are arranged to face each other with a space in the radial direction R with respect to the third axis X3. And the pair of pinion gears 523 are attached to a pinion shaft 52a supported so as to rotate integrally with the differential case 522. Each of the pair of pinion gears 523 is configured to be rotatable (self-rotate) about the pinion shaft 52a and rotatable (revolve) about the third axis X3.

[0057] A pair of side gears 524 mesh with the pair of pinion gears 523. The pair of side gears 524 are arranged to rotate about the third axis X3 as the rotation axis. The pair of side gears 524 are arranged with a space in the axial direction L with respect to each other and face each other with the pinion shaft 52a interposed therebetween.

[0058] In the present embodiment, the differential case 522 is rotatably supported with respect to the case 9 by a first differential bearing B6 and a second differential bearing B7.

[0059] In the present embodiment, the first differential bearing B6 is arranged to support the end portion on the first axial side L1 of the differential case 522 from the outside in the radial direction R. In the example shown in FIG. 1, the third side wall portion 94b of the case 9 has a first differential bearing support portion 94d. The first differential bearing support portion 94d is formed in a cylindrical shape protruding in the second axial side L2 so as to overlap the end portion on the first axial side L1 of the differential case 522 in a view in the radial direction R along the radial direction R outside the end portion on the first axial side L1 of the differential case 522. And the first differential bearing B6 is arranged between the inner peripheral surface of the first differential bearing support portion 94d and the outer peripheral surface of the end portion on the first axial side L1 of the differential case 522.

[0060] Further, in the present embodiment, the second differential bearing B7 is arranged to support the end portion of the differential case 522 on the second axial side L2 from the outside in the radial direction R. In the example shown in FIG. 1, the fourth side wall portion 94c of the case 9 has a second differential bearing support portion 94e. The second differential bearing support portion 94e is formed in a cylindrical shape protruding in the first axial side L1 so as to overlap the end portion of the differential case 522 on the second axial side L2 in a view in the radial direction R along the radial direction R outside the end portion of the differential case 522 on the second axial side L2. And the second differential bearing B7 is arranged between the inner peripheral surface of the second differential bearing support portion 94e and the outer peripheral surface of the end portion of the differential case 522 on the second axial side L2.

[0061] In the present embodiment, each of the pair of output members 4 is connected so as to rotate integrally with the side gear 524. And each of the pair of output members 4 is connected so as to rotate integrally with a drive shaft DS drivingly connected to the wheel W. In the example shown in FIG. 1, each of the pair of output members 4 is formed in a cylindrical shape centered on the third axis X3. And they are connected to each other by spline engagement with the drive shaft DS arranged inside in the radial direction R with respect to each of the pair of output members 4.

[0062] In the present embodiment, the rotation sensor 7 is arranged between the rotor 12 and the third bearing B3 in the axial direction L. In the example shown in FIG. 3, the rotation sensor 7 is arranged at a position outside in the radial direction R with respect to the sensor rotor fixing portion 22. The rotation sensor 7 includes a sensor stator 71 and a sensor rotor 72. In this example, the rotation sensor 7 is configured as a resolver. Therefore, the rotation sensor 7 detects the phase of the alternating voltage corresponding to the relative angle of the sensor rotor 72 with respect to the sensor stator 71 when an alternating current is passed through the coil provided in the sensor stator 71, and detects the rotational position of the rotor 12. Note that the rotation sensor 7 is not limited to a resolver, and can be configured by various sensors such as a Hall element sensor, an encoder, a magnetic rotational sensor, and an eddy current rotational sensor.

[0063] In this embodiment, the sensor stator 71 is supported by the intermediate support portion 90a. The sensor stator 71 is disposed on the first side L1 in the axial direction with respect to the intermediate support portion 90a.

[0064] The sensor rotor 72 is connected so as to rotate integrally with the rotor shaft 2. And the sensor rotor 72 is disposed so as to face the sensor stator 71 from the inner side in the radial direction R. In the example shown in FIG. 3, the sensor rotor 72 is disposed on the outer side in the radial direction R with respect to the sensor rotor fixing portion 22. Specifically, the sensor rotor 72 is fitted to the outer peripheral surface of the sensor rotor fixing portion 22. And in the example shown in FIG. 3, the sensor rotor 72 abuts on the step surface 22b between the rotor fixing portion 21 and the sensor rotor fixing portion 22 in the axial direction L. Therefore, the positioning of the sensor rotor 72 with respect to the rotor shaft 2 can be easily performed by the step surface 22b.

[0065] Hereinafter, with reference to FIG. 4, the assembling operation of the rotor shaft 2 performed in the manufacturing process of the vehicle drive device 100 according to this embodiment will be described.

[0066] The assembling operation of the rotor shaft 2 includes an operation of rotatably supporting the rotor shaft 2 by the first bearing B1, the second bearing B2, and the third bearing B3. Here, the operation of supporting the rotor shaft 2 by the third bearing B3 will be described. In order to support the rotor shaft 2 by the third bearing B3, as shown in FIG. 4, each of the third bearing B3 and the rotation sensor 7 is attached to a specified position before the assembling operation of the rotor shaft 2 is performed. In this embodiment, each of the third bearing B3 and the rotation sensor 7 is attached to the intermediate support portion 90a of the case 9. Also, in this embodiment, before the assembling operation of the rotor shaft 2 is performed, each of the rotating electric machine 1 and the first bearing B1 is attached to a specified position. In the example shown in FIG. 4, the stator 11 of the rotating electric machine 1 is attached to the case 9. And the rotor 12 of the rotating electric machine 1 is attached to the rotor fixing portion 21.

[0067] In the assembly operation of the rotor shaft 2, the rotor shaft 2 is inserted from the first axial side L1 inside the radial direction R with respect to the sensor stator 71. Here, the outer diameter 3a of the first gear 3 is smaller than the inner diameters of the sensor stator 71 and the third bearing B3, respectively. Therefore, the first gear 3 can pass inside the radial direction R with respect to the sensor stator 71 and the third bearing B3, respectively.

[0068] In the assembly operation of the rotor shaft 2, the rotor shaft 2 in a state where the first gear 3 has passed inside the radial direction R with respect to the third bearing B3 is further moved to the second axial side L2 and arranged at a specified position. As shown in FIGS. 1 and 3, this specified position is such that the stepped surface 23a of the stepped portion 23 of the rotor shaft 2 faces the third bearing B3 and the bearing fitting portion 24 fits with the third bearing B3. Further, in the present embodiment, since the sensor rotor 72 is attached to the rotor shaft 2, the specified position where the rotor shaft 2 is arranged is a position where the sensor rotor 72 is arranged inside the radial direction R with respect to the sensor stator 71. Further, in the present embodiment, since the rotor 12 is attached to the rotor shaft 2, the specified position where the rotor shaft 2 is arranged is a position where the rotor 12 is arranged inside the radial direction R with respect to the stator 11.

[0069] In the subsequent assembly operation of the rotor shaft 2, there are steps of attaching the second bearing B2 to the rotor shaft 2, attaching the first bearing B1 to the case 9, and attaching the second bearing B2 to the case 9.

[0070] 〔Other Embodiments〕 (1) In the above-described embodiment, the vehicle drive device 100 having a three-axis configuration in which the rotating electrical machine 1, the counter gear mechanism 51, and the differential gear mechanism 52 are arranged on different parallel axes has been described as an example. However, the vehicle drive device 100 may have, for example, a two-axis configuration in which a planetary gear mechanism is arranged coaxially with the rotating electrical machine 1 and the rotating electrical machine 1 and the differential gear mechanism 52 are arranged on different parallel axes. Further, in the above-described embodiment, the power transmission mechanism 5 having the counter gear mechanism 51 and the differential gear mechanism 52 has been described as an example. However, the vehicle drive device 100 may have a configuration including only one of the counter gear mechanism 51 and the differential gear mechanism 52, or a configuration in which the power transmission mechanism 5 includes neither the counter gear mechanism 51 nor the differential gear mechanism 52. Further, in addition to the rotating electrical machine 1, an internal combustion engine may also function as a driving force source for the wheels W, that is, the vehicle drive device 100 may be configured to be mounted on a hybrid vehicle.

[0071] (2) In the above-described embodiment, it has been described that the intermediate support portion 90a is integrally formed with the partition portion 91. However, the intermediate support portion 90a may be separable from the first case portion 9A including the partition portion 91. In this case, the intermediate support portion 90a is assembled to the rotor shaft 2 from the second side L2 in the axial direction.

[0072] (3) Note that the configurations disclosed in the above-described embodiments can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs. Regarding other configurations as well, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be appropriately made without departing from the spirit of the present disclosure.

[0073] Summary of this embodiment The summary of the embodiment related to the vehicle drive device (100) described above will be described below.

[0074] The vehicle drive device (100) includes a rotating electric machine (1) having a rotor (12), an output member (4) drivingly connected to a wheel (W), a rotor shaft (2) fixed to the rotor (12) so as to rotate integrally with the rotor (12), a first gear (3) integrally formed on the rotor shaft (2), a second gear (511) meshing with the first gear (3), a power transmission mechanism (5) drivingly connecting the second gear (511) and the output member (4), a rotation sensor (7) for detecting the rotation of the rotor (12), and a case (9) housing the rotating electric machine (1), the rotor shaft (2), the power transmission mechanism (5), and the rotation sensor (7). The direction along the axis of the rotor shaft (2) is defined as the axial direction (L), the direction orthogonal to the axis is defined as the radial direction (R), one side of the axial direction (L) is defined as the first axial side (L1), and the other side of the axial direction (L) is defined as the second axial side (L2). The first gear (3) is arranged on the second axial side (L2) with respect to the rotor (12). The rotor shaft (2) is rotatably supported by the case (9) at three positions in the axial direction (L) by a first bearing (B1), a second bearing (B2), and a third bearing (B3). The first bearing (B1) is arranged on the first axial side (L1) with respect to the rotor (12). The second bearing (B2) is arranged on the second axial side (L2) with respect to the first gear (3). The third bearing (B3) is arranged between the rotor (12) and the first gear (3) in the axial direction (L). The case (9) includes an intermediate support portion (90a) for supporting the third bearing (B3) from the outside in the radial direction (R). The rotation sensor (7) includes a sensor stator (71) arranged between the rotor (12) and the third bearing (B3) in the axial direction (L) and supported by the intermediate support portion (90a). The outer diameter of the third bearing (B3) is smaller than the inner diameter of the sensor stator (71), and the inner diameter of the third bearing (B3) is larger than the outer diameter of the first gear (3).

[0075] According to this configuration, since the first gear (3) is integrally formed on the rotor shaft (2), compared with the case where the rotor shaft (2) and the first gear (3) are separated, the misalignment of the axial centers of the rotor shaft (2) and the first gear (3) can be reduced, and the occurrence of vibration (vibration caused by wobbling) due to such misalignment of the axial centers can be suppressed. Further, according to this configuration, since the fitting portion between the rotor shaft (2) and the first gear (3) which is required when the rotor shaft (2) and the first gear (3) are separated can be made unnecessary, it is easy to reduce the manufacturing cost. Furthermore, according to this configuration, since the third bearing (B3) can pass through the outside in the radial direction (R) of the first gear (3) in the axial direction (L), the third bearing (B3) can be assembled to the rotor shaft (2) from the second side (L2) in the axial direction. At the same time, since the third bearing (B3) can pass through the inside in the radial direction (R) of the sensor stator (71) in the axial direction (L), the rotor shaft (2) with the third bearing (B3) assembled can be inserted into the sensor stator (71) from the first side (L1) in the axial direction. Therefore, the assembly of the third bearing (B3) to the rotor shaft (2) and the assembly of the rotor shaft (2) to the case (9) are facilitated, and it is easy to facilitate the assembly work of the vehicle drive device (100). From the above, it is possible to reduce the vibration of the rotor shaft (2) and the manufacturing cost, and a vehicle drive device (100) that is easy to assemble can be realized.

[0076] Here, the rotor shaft (2) includes a rotor fixing portion (21) to which the rotor (12) is fixed, a sensor rotor fixing portion (22) to which the sensor rotor (72) of the rotation sensor (7) is fixed, a stepped portion (23) having a stepped surface (23a) facing the second side (L2) in the axial direction, and a bearing fitting portion (24) into which the third bearing (B3) is fitted. The rotor fixing portion (21), the sensor rotor fixing portion (22), the stepped portion (23), and the bearing fitting portion (24) are arranged in the described order along the axial direction (L) from the first side (L1) in the axial direction. The outer diameter (24a) of the bearing fitting portion (24) is preferably larger than the outer diameter (3a) of the first gear (3), and the outer diameter (22a) of the sensor rotor fixing portion (22) is preferably larger than the outer diameter (24a) of the bearing fitting portion (24).

[0077] According to this configuration, the sensor rotor (72) can be moved from the second axial side (L2) to the first axial side (L1) with respect to the rotor shaft (2), and the sensor rotor (72) can be assembled to the sensor rotor fixing portion (22). Also, the third bearing (B3) can be moved from the second axial side (L2) to the first axial side (L1) with respect to the rotor shaft (2), and the third bearing (B3) can be assembled to the bearing fitting portion (24). Then, the positioning in the axial direction (L) of the third bearing (B3) fitted to the bearing fitting portion (24) can be performed by the step portion (23). Therefore, the assembly of the sensor rotor (72) and the third bearing (B3) to the rotor shaft (2) becomes easy.

[0078] Further, the third bearing (B3) preferably includes an outer ring (B31) having conductivity, a plurality of rolling elements (B32) housed inside the outer ring (B31) in the radial direction (R), and an annular connecting member (B33) having conductivity. The connecting member (B33) is arranged at different positions in the axial direction (L) with respect to the plurality of rolling elements (B32), and is configured to contact both the outer ring (B31) and the outer peripheral surface of the rotor shaft (2), or to contact both the outer ring (B31) and the inner ring when the third bearing (B3) includes an inner ring having conductivity.

[0079] According to this configuration, when the third bearing (B3) includes an outer ring (B31) and a connecting member (B33) and does not include an inner ring, the outer ring (B31) and the connecting member (B33) can function to conduct electricity between the rotor shaft (2) and the intermediate support portion (90a) of the case (9). When the third bearing (B3) includes an outer ring (B31), a connecting member (B33), and an inner ring, the outer ring (B31), the connecting member (B33), and the inner ring can function to conduct electricity between the rotor shaft (2) and the intermediate support portion (90a) of the case (9). Therefore, according to this configuration, it is easy to reduce the occurrence of electric corrosion of the rolling elements (B32). As a result, for the purpose of preventing electric corrosion of the rolling elements (B32), for example, it is not necessary to use a non-conductive material (such as ceramic) for the rolling elements (B32) or to provide a brush for grounding the rotor shaft (2), so it is easy to reduce the manufacturing cost of the vehicle drive device (100). Further, according to this configuration, since the connecting member (B33) can have a sealing property, when it is desired to restrict the flow of a liquid such as oil between the side where the rotating electrical machine (1) is disposed and the side where the first gear (3) is disposed with respect to the intermediate support portion (90a), the necessity of separately providing a sealing member can be reduced. Therefore, also in this respect, it is easy to reduce the manufacturing cost of the vehicle drive device (100).

[0080] Further, the third bearing (B3) includes an outer ring (B31), a plurality of needle rollers housed inside the outer ring (B31) in the radial direction (R), and a cage (B35) that holds the intervals between the plurality of needle rollers, and is a shell-type needle roller bearing that does not include an inner ring.

[0081] According to this configuration, it is easy to keep the thickness of the third bearing (B3) in the radial direction (R) small. Therefore, it is easy to configure the third bearing (B3) such that its outer diameter is smaller than the inner diameter of the sensor stator (71) and its inner diameter is larger than the outer diameter of the first gear (3).

Industrial Applicability

[0082] The technology according to the present disclosure can be used in a vehicle drive device including a rotating electrical machine having a rotor, an output member drivingly connected to a wheel, a rotor shaft that rotates integrally with the rotor, and a power transmission mechanism that transmits the rotation of the rotor shaft to the output member.

Explanation of Signs

[0083] 100: Vehicle drive device, 1: Rotating electrical machine, 12: Rotor, 2: Rotor shaft, 21: Rotor fixing portion, 22: Sensor rotor fixing portion, 23: Step portion, 23a: Step surface, 24: Bearing fitting portion, 3: First gear, 3a: Outer diameter, 4: Output member, 5: Power transmission mechanism, 511: Second gear, 7: Rotation sensor, 71: Sensor stator, 72: Sensor rotor, 9: Case, 90a: Intermediate support portion, B1: First bearing, B2: Second bearing, B3: Third bearing, B31: Outer ring, B32: Rolling element, B33: Connecting member, B35: Retainer, R: Radial direction, L: Axial direction, L1: First axial side, L2: Second axial side, W: Wheel

Claims

1. A rotating electrical machine including a rotor, An output member drivingly connected to a wheel, A rotor shaft fixed to the rotor so as to rotate integrally with the rotor, A first gear integrally formed on the rotor shaft, A power transmission mechanism including a second gear meshing with the first gear and drivingly connecting the second gear and the output member, A rotation sensor for detecting rotation of the rotor, A case housing the rotating electrical machine, the rotor shaft, the power transmission mechanism, and the rotation sensor, With the direction along the axis of the rotor shaft as the axial direction, the direction orthogonal to the axis as the radial direction, one side in the axial direction as the first axial side, and the other side in the axial direction as the second axial side, The first gear is disposed on the second axial side with respect to the rotor, The rotor shaft is rotatably supported by a first bearing, a second bearing, and a third bearing at three locations in the axial direction with respect to the case, The first bearing is disposed on the first axial side with respect to the rotor, The second bearing is disposed on the second axial side with respect to the first gear, The third bearing is disposed between the rotor and the first gear in the axial direction, The case includes an intermediate support portion that supports the third bearing from the outside in the radial direction, The rotation sensor is disposed between the rotor and the third bearing in the axial direction, Including a sensor stator supported by the intermediate support portion, The outer diameter of the third bearing is smaller than the inner diameter of the sensor stator, The inner diameter of the third bearing is larger than the outer diameter of the first gear, a drive device for a vehicle.

2. The rotor shaft, A rotor fixing portion to which the rotor is fixed, A sensor rotor fixing part to which the sensor rotor of the rotation sensor is fixed, A stepped part having a stepped surface facing the second side in the axial direction, And a bearing fitting part into which the third bearing is fitted. The rotor fixing part, the sensor rotor fixing part, the stepped part, and the bearing fitting part are arranged in the described order along the axial direction from the first side in the axial direction. The outer diameter of the bearing fitting part is larger than the outer diameter of the first gear, and the outer diameter of the sensor rotor fixing part is larger than the outer diameter of the bearing fitting part. The vehicle drive device according to claim 1.

3. The third bearing, An outer ring having conductivity, A plurality of rolling elements accommodated radially inward of the outer ring, And an annular connecting member having conductivity. The connecting member is arranged at different positions in the axial direction with respect to the plurality of rolling elements, and is configured to contact both the outer ring and the outer peripheral surface of the rotor shaft, or to contact both the outer ring and the inner ring when the third bearing includes an inner ring having conductivity. The vehicle drive device according to claim 1 or 2.

4. The third bearing, An outer ring, A plurality of needle rollers accommodated radially inward of the outer ring, And a cage for holding the intervals of the plurality of needle rollers. It is a shell-type needle roller bearing without an inner ring. The vehicle drive device according to claim 1 or 2.

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