阅读说明：本技术 动力传递装置 (Power transmission device ) 是由 大木真二郎 于 2019-12-03 设计创作，主要内容包括：具有：第一行星减速齿轮(4)、与第一行星减速齿轮(4)的下游连接的第二行星减速齿轮(减速齿轮)(5)、以及停车锁止机构(7),停车锁止机构(7)通过形成为卡止第一行星减速齿轮(4)的行星齿轮架(5)的结构的动力传递装置(1),经由第二行星减速齿轮(5)从输出侧(驱动轮侧)向停车锁止机构(7)输入转矩,因此,能够减小施加于停车锁止机构(7)的转矩。(Comprising: the parking lock mechanism (7) is configured such that a torque is input from an output side (drive wheel side) to the parking lock mechanism (7) via the second planetary reduction gear (5) by means of the power transmission device (1) configured to lock the carrier (5) of the first planetary reduction gear (4), and therefore the torque applied to the parking lock mechanism (7) can be reduced.)

1. A power transmission device is characterized by comprising:

a planetary gear;

a reduction gear connected downstream of the planetary gear;

a parking lock mechanism is arranged on the vehicle body,

the parking lock mechanism holds one of the rotary elements of the planetary gear.

2. The power transmission device according to claim 1,

the parking pawl of the parking lock mechanism, the planetary gear, and the reduction gear are axially overlapped.

3. The power transmission device according to claim 2,

a partition wall is provided between the planetary gear and the reduction gear,

the parking pawl is rotatably supported by the partition wall.

4. The power transmission device according to any one of claims 1 to 3,

the parking lock mechanism locks an outer peripheral side of a carrier of the planetary gear.

5. The power transmission device according to any one of claims 1 to 4,

the planetary gear is connected downstream of the motor,

the motor overlaps with the planetary gear in the axial direction.

Technical Field

The present invention relates to a power transmission device.

Background

Patent document 1 discloses a power transmission device for an electric vehicle.

It is preferable that the torque input from the output side (drive wheel side) to the parking lock mechanism during parking be as small as possible.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-103676

Disclosure of Invention

The power transmission device of the present invention includes:

a planetary gear;

a reduction gear connected downstream of the planetary gear;

a parking lock mechanism is arranged on the vehicle body,

the parking lock mechanism holds one of the rotary elements of the planetary gear.

According to the present invention, it is possible to reduce the torque input from the output side (drive wheel side) to the parking lock mechanism at the time of parking.

Drawings

Fig. 1 is a diagram illustrating a power transmission device according to the present embodiment.

Fig. 2 is a diagram illustrating the power transmission device according to the present embodiment.

Fig. 3 is a diagram illustrating a power transmission device according to the present embodiment.

Fig. 4 is a diagram illustrating the parking lock mechanism.

Fig. 5 is a diagram illustrating a power transmission device according to a modification.

Fig. 6 is a diagram illustrating a power transmission device according to a modification.

Fig. 7 is a diagram illustrating a power transmission device according to a modification.

Detailed Description

The following describes embodiments of the present invention.

Fig. 1 is a diagram illustrating a power transmission device 1 according to the present embodiment.

Fig. 2 is a diagram illustrating the power transmission device 1 of the present embodiment, and is an enlarged view of the periphery of the reduction mechanism 3 (the first planetary reduction gear 4 and the second planetary reduction gear 5) of the power transmission device 1.

Fig. 3 is a diagram illustrating the power transmission device 1 of the present embodiment, and is an enlarged view of a region a in fig. 1.

Fig. 4 is a view for explaining the parking lock mechanism 7, and is a view schematically showing a section a-a in fig. 3.

The power transmission device 1 includes: the motor 2, the reduction mechanism 3 (the first planetary reduction gear 4, the second planetary reduction gear 5) that reduces the output rotation of the motor 2 and inputs the reduced output rotation to the differential device 6, and the drive shaft 8(8A, 8B).

In the power transmission device 1, a transmission path along which the output rotation of the motor 2 is transmitted is provided with: a reduction mechanism 3 (a first planetary reduction gear 4, a second planetary reduction gear 5), a differential device 6, and a drive shaft 8(8A, 8B).

The output rotation of the electric motor 2 is reduced in speed by the reduction mechanism 3, input to the differential device 6, and then transmitted to left and right drive wheels (not shown) of a vehicle on which the power transmission device 1 is mounted via a drive shaft 8(8A, 8B). In fig. 1, a drive shaft 8A is connected to a left wheel of a vehicle mounted with the power transmission device 1 so as to be rotatable, and a drive shaft 8B is connected to a right wheel so as to be rotatable.

Here, the first planetary reduction gear 4 is connected downstream of the motor 2, and the second planetary reduction gear 5 is connected downstream of the first planetary reduction gear 4. The differential device 6 is connected downstream of the second planetary reduction gear 5, and the drive shafts 8A, 8B are connected downstream of the differential device 6.

The motor 2 includes: a cylindrical motor shaft 20, a cylindrical rotor core 21 externally fitted to the motor shaft 20, and a stator core 25 surrounding the outer periphery of the rotor core 21 at a predetermined interval.

The motor shaft 20 is provided so as to be relatively rotatable with respect to the drive shaft 8B in a state of being externally inserted on the drive shaft 8B.

The bearings B1 and B1 are externally fitted and fixed to the outer peripheries of the motor shaft 20 on the one end 20a side and the other end 20B side in the longitudinal direction.

The one end 20a side of the motor shaft 20 is rotatably supported by the cylindrical motor support portion 121 of the intermediate housing 12 via a bearing B1.

The other end 20B of the motor shaft 20 is rotatably supported by the cylindrical motor support portion 111 of the cover 11 via a bearing B1.

The motor 2 includes a motor case 10 surrounding the outer periphery of the rotor core 21 at predetermined intervals. In the present embodiment, the intermediate case 12 is joined to one end 10a of the motor case 10, and the cover 11 is joined to the other end 10b of the motor case 10.

The motor case 10 is provided with a seal ring S, S at one end 10a and the other end 10 b. One end 10a of the motor casing 10 is joined to the cylindrical base 120 of the intermediate case 12 without a gap by a seal ring S provided at the one end 10 a.

The other end 10b of the motor housing 10 is joined to the annular joint portion 110 of the cover 11 with no gap by a seal ring S provided on the other end 10 b.

In the intermediate housing 12, a motor support portion 121 is provided on the one end 120a side of the base portion 120 in the rotation axis X direction.

In the present embodiment, when one end 120a of the base 120 is fixed to one end 10a of the motor housing 10, the motor support portion 121 is inserted into the motor housing 10.

In this state, the motor support portion 121 is disposed to face the one end portion 21a of the rotor core 21 with a gap in the direction of the rotation axis X on the inner diameter side of the coil end 253a (see fig. 2).

The connection portion 123 connecting the base portion 120 and the motor support portion 121 is provided so as to avoid contact with the coil end 253a and a side plate portion 452 described later.

Further, a bearing holder 125 is fixed to an end face 121a of the motor support portion 121 on the rotor core 21 side.

The bearing holder 125 is annular when viewed from the direction of the rotation axis X. The inner diameter side of the bearing holder 125 abuts against the side surface of the outer ring B1B of the bearing B1 supported by the motor support portion 121 from the rotation axis X direction. The bearing holder 125 prevents the bearing B1 from falling off from the motor support portion 121.

In the cover 11, the engaging portion 110 and the motor supporting portion 111 are provided in a staggered position in the rotation axis X direction.

In the present embodiment, when the joint portion 110 of the cover 11 is fixed to the other end 10b of the motor housing 10, the motor support portion 111 is inserted into the motor housing 10.

In this state, the motor support portion 111 is disposed opposite to the other end portion 21b of the rotor core 21 with a gap in the direction of the rotation axis X on the inner diameter side of the coil end 253b, which will be described later.

The connection portion 115 connecting the joint portion 110 and the side wall portion 113 of the cover 11 is provided so as to avoid contact with the coil end 253b and a support cylinder 112 described later.

Inside the motor case 10, a rotor core 21 is disposed between the motor support portion 111 on the cover 11 side and the motor support portion 121 on the intermediate case 12 side.

The rotor core 21 is formed by laminating a plurality of silicon steel plates, and each silicon steel plate is inserted to the motor shaft 20 in a state where relative rotation with the motor shaft 20 is restricted.

The silicon steel plate is formed in a ring shape when viewed from the direction of the rotation axis X of the motor shaft 20, and magnets of N-pole and S-pole, not shown, are alternately provided on the outer peripheral side of the silicon steel plate in the circumferential direction around the rotation axis X.

One end portion 21a of the rotor core 21 in the rotation axis X direction is positioned by the large diameter portion 206 of the motor shaft 20. The other end 21b of the rotor core 21 is positioned by a stopper 23 pressed into the motor shaft 20.

Stator core 25 is formed by laminating a plurality of electromagnetic steel sheets, each of which has: an annular yoke portion 251 fixed to the inner periphery of the motor case 10, and a tooth portion 252 protruding from the inner periphery of the yoke portion 251 toward the rotor core 21.

In the present embodiment, the stator core 25 is configured such that the windings 253 are wound so as to be distributed across the plurality of teeth 252, and the length of the stator core 25 in the direction of the rotation axis X is longer than the length of the rotor core 21 in the direction of the rotation axis X by the coil ends 253a and 253b protruding in the direction of the rotation axis X.

Further, a stator core may be employed in which the windings 253 are wound in a concentrated manner on each of the plurality of teeth 252 protruding toward the rotor core 21.

A bearing B1 is press-fitted into the motor shaft 20 on the outer periphery of the region closer to the one end 20a than the large diameter portion 206.

As shown in fig. 2, one side surface of the inner race B1a of the bearing B1 in the direction of the rotation axis X abuts against a step 204 provided on the outer periphery of the motor shaft 20. The other side surface of the inner race B1a abuts against an annular stopper 205 press-fitted into the outer periphery of the motor shaft 20.

The bearing B1 is positioned by the stopper 205 at a position where the inner race B1a abuts against the step portion 204.

One end 20a of the motor shaft 20 is positioned closer to the differential unit 6 than the stopper 205 (left side in the drawing). One end 20a faces a side surface 41a of the sun gear 41 of the first planetary reduction gear 4 with a space therebetween in the rotation axis X direction.

The cylindrical wall 122 is located radially outward of the motor shaft 20 on the one end 20a side of the motor shaft 20.

The cylindrical wall 122 protrudes from the motor support portion 121 toward the differential device 6, and a tip end 122a of the cylindrical wall 122 faces the side surface 41a of the sun gear 41 of the first planetary reduction gear 4 with a gap.

The cylindrical wall 122 surrounds the outer periphery of the motor shaft 20 at a predetermined interval, and a lip seal RS is provided between the cylindrical wall 122 and the motor shaft 20.

The lip seal RS is provided to partition a space Sa (see fig. 1) on the inner diameter side of the motor case 10 and a space Sb (see fig. 1) on the inner diameter side of the intermediate case 12.

The space Sb on the inner diameter side of the intermediate case 12 communicates with a space Sc in the case 13 accommodating the differential device 6 described later, and seals the lubricant oil of the differential device 6. The lip seal RS is provided to prevent the lubricating oil from flowing into the space Sa on the inner diameter side of the motor housing 10.

As shown in fig. 2, a region 202 on the one end 20a side of the motor shaft 20 is formed with a larger inner diameter than a region 201 in which the rotor core 21 is externally inserted.

A cylindrical coupling portion 411 of the sun gear 41 is inserted into the region 202 on the one end 20a side. In this state, the region 202 on the one end 20a side of the motor shaft 20 is spline fitted to the coupling portion 411 of the sun gear 41 so as not to be relatively rotatable.

Therefore, the output rotation of the motor 2 is input to the sun gear 41 of the first planetary reduction gear 4 via the motor shaft 20, and the sun gear 41 is rotated about the rotation axis X by the rotational driving force of the motor 2.

The sun gear 41 has a coupling portion 411 extending from the inner diameter side surface 41a in the direction of the rotation axis X. The coupling portion 411 is formed integrally with the sun gear 41. A through hole 410 is formed across the inner diameter side of the sun gear 41 and the inner diameter side of the coupling portion 411.

The sun gear 41 is rotatably supported by the outer periphery of the drive shaft 8B penetrating the through hole 410.

The ring gear 42 of the first planetary reduction gear 4 fixed to the inner periphery of the base portion 120 of the intermediate housing 12 is located on the outer diameter side of the sun gear 41 in the radial direction of the rotation axis X. In the radial direction of the rotation axis X, between the sun gear 41 and the ring gear 42, a pinion gear 43 rotatably supported by a pinion shaft 44 meshes with the outer periphery of the sun gear 41 and the inner periphery of the ring gear 42.

The pinion gear 43 is rotatably supported by the outer periphery of the pinion gear 43 via a needle bearing NB. The pinion shaft 44 penetrates the pinion 43 in the direction of the axis X1 along the rotation axis X. One end and the other end of the pinion shaft 44 in the longitudinal direction are supported by the pair of side plate portions 451, 452 of the carrier 45 of the first planetary reduction gear 4.

The side plate portions 451, 452 are provided in parallel to each other with a gap in the rotation axis X direction.

Between the side plate portions 451, 452, a plurality of pinion gears 43 (for example, 4) are provided at predetermined intervals in the circumferential direction around the rotation axis X.

The side plate portion 451 is annular when viewed from the rotation axis X direction.

As shown in fig. 1, the side plate portion 451 is surrounded by the base portion 120 of the intermediate housing 12 over the entire circumference in the circumferential direction around the rotation axis X. The outer peripheral surface of the side plate portion 451 faces the inner peripheral surface of the base portion 120 in the radial direction of the rotation axis X.

A parking gear 71 of a parking lock mechanism 7 described later is formed on the outer periphery of the side plate portion 451. The parking gear 71 is formed over the entire circumference of the outer peripheral surface of the side plate portion 451 in the circumferential direction around the rotation axis X. The parking gear 71 is formed integrally with the side plate portion 451, and rotates about the rotation axis X integrally with the side plate portion 451.

The parking gear 71 is provided with a tooth groove portion 71a (see fig. 4) for engaging and disengaging the parking pawl 70, which will be described later. The tooth groove portions 71a are provided at predetermined intervals over the entire circumference in the circumferential direction around the rotation axis X.

As shown in fig. 3, a recess 129 is formed in the base portion 120 of the intermediate housing 12 at a position facing the side plate portion 451 in the radial direction of the rotation axis X. The concave portion 129 is formed below the rotation axis X in the vertical line VL direction in the installed state of the power transmission device 1. The other end 120b of the base 120 in the direction of the rotation axis X is open to the recess 129.

The recess 129 accommodates a parking lock mechanism 7 described later. The length L of the recess 129 in the radial direction of the rotation axis X is set to a length that does not interfere with engagement and disengagement of the parking pawl 70 with and from the tooth groove portion 71 a.

As shown in fig. 2, a cylindrical coupling portion 453 is provided on the side plate portion 451 located on the differential device 6 side.

The side plate portion 451 has a connection portion 453 that is disposed concentrically with the rotation axis X and protrudes in a direction approaching the differential unit 6 along the rotation axis X (in the left direction in the drawing).

The annular intermediate cover 14 is located on the other end 120b side of the base 120 of the intermediate housing 12. The intermediate cover 14 is provided in a state of being sandwiched between the intermediate case 12 and the case 13.

The connection portion 453 provided on the inner diameter side of the side plate portion 451 extends through the opening 140 in the center of the intermediate cover 14 from the motor 2 side to the left of the differential device 6 side.

The front end 453a of the coupling portion 453 is positioned in the case 13 attached to the intermediate cover 14. The tip 453a of the coupling portion 453 faces the side surface 51a of the sun gear 51 of the second planetary reduction gear 5 with a gap therebetween in the rotation axis X direction.

A cylindrical coupling portion 511 extending from the sun gear 51 is inserted into and spline-fitted to the inside of the coupling portion 453, and the coupling portion 453 on the first planetary reduction gear 4 side and the coupling portion 511 on the second planetary reduction gear 5 side are coupled so as not to be relatively rotatable.

Sun gear 51 has coupling portion 511 extending from inner diameter side surface 51a in the direction of rotation axis X. Coupling portion 511 is formed integrally with sun gear 51, and has through hole 510 formed across the inner diameter side of sun gear 51 and the inner diameter side of coupling portion 511.

The sun gear 51 is rotatably supported by the outer periphery of the drive shaft 8B penetrating the through hole 510.

A side surface 51b of the sun gear 51 on the differential device 6 side faces a cylindrical support portion 601 of the differential case 60, which will be described later, with a gap in the rotation axis X direction therebetween, and a needle bearing NB is interposed between the side surface 51b and the support portion 601.

The sun gear 51 meshes with the large diameter gear portion 531 of the stepped pinion 53 on the extension line of the connecting portion 542 on the first planetary reduction gear 4 side.

The stepped pinion 53 has: a large diameter gear portion 531 meshing with the sun gear 51, and a small diameter gear portion 532 having a smaller diameter than the large diameter gear portion 531.

The stepped pinion gears 53 are gear members in which a large-diameter gear portion 531 and a small-diameter gear portion 532 are arranged in line in the direction of an axis X2 parallel to the rotation axis X and are integrally provided.

The stepped pinion 53 has a through hole 530 penetrating the large diameter gear portion 531 and the small diameter gear portion 532 on the inner diameter side in the axis X2 direction.

The stepped pinion 53 is rotatably supported via a needle bearing NB by the outer periphery of the pinion shaft 54 inserted through the through hole 530.

One end and the other end of the pinion shaft 54 in the longitudinal direction are supported by a side plate portion 651 formed integrally with the differential case 60 and a side plate portion 551 disposed at a distance from the side plate portion.

The side plate portions 651, 551 are arranged in parallel to each other at intervals in the direction of the rotation axis X.

Between the side plate portions 651, 551, a plurality of (e.g., 3) stepped pinions 53 are provided at predetermined intervals in the circumferential direction around the rotation axis X.

Each small-diameter gear portion 532 meshes with the inner periphery of the ring gear 52. The ring gear 52 is spline-fitted to the inner periphery of the housing 13, and relative rotation between the ring gear 52 and the housing 13 is restricted.

A cylindrical portion 552 extending toward the first planetary reduction gear 4 is provided on the inner diameter side of the side plate portion 551. The cylindrical portion 552 penetrates the opening 140 in the center of the intermediate cover 14 from the differential unit 6 side to the electric motor 2 side (right side in the drawing). In the rotation axis X direction, the front end 552a of the cylindrical portion 552 faces the side plate portion 451 of the carrier 45 of the first planetary reduction gear 4 with a gap.

The cylindrical portion 552 is located radially outward of the meshing portion between the coupling portion 453 on the first planetary reduction gear 4 side and the coupling portion 511 on the second planetary reduction gear 5 side. The bearing B2 fixed to the inner periphery of the opening 140 of the intermediate cover 14 contacts the outer periphery of the cylindrical portion 552. The cylindrical portion 552 of the side plate portion 551 is rotatably supported by the intermediate cover 14 via a bearing B2.

In the second planetary reduction gear 5, one side plate portion 651 of the side plate portions 551 and 651 constituting the carrier 55 is formed integrally with the differential case 60 of the differential device 6.

In the second planetary reduction gear 5, the output rotation of the motor 2 reduced by the first planetary reduction gear 4 is input to the sun gear 51.

The output rotation input to the sun gear 51 is input to the stepped pinion 53 via the large-diameter gear portion 531 meshing with the sun gear 51, and the stepped pinion 53 rotates about the axis X2.

Then, the small diameter gear portion 532 formed integrally with the large diameter gear portion 531 rotates around the axis X2 integrally with the large diameter gear portion 531.

Here, the small-diameter gear portion 532 meshes with the ring gear 52 fixed to the inner periphery of the housing 13. Therefore, when the small-diameter gear portion 532 rotates about the axis X2, the stepped pinion 53 rotates about the axis X2 and also rotates about the rotation axis X.

Then, since one end of the pinion shaft 54 is supported by the side plate portion 651 integrally formed with the differential case 60, the differential case 60 rotates about the rotation axis X in conjunction with the displacement of the stepped pinion 53 in the circumferential direction about the rotation axis X.

Here, in the stepped pinion 53, the outer diameter R2 of the small-diameter gear portion 532 is smaller than the outer diameter R1 of the large-diameter gear portion 531 (see fig. 2).

In the second planetary reduction gear 5, the sun gear 51 serves as an input portion for the output rotation of the electric motor, and the carrier 55 supporting the stepped pinion gear 53 serves as an output portion for the input rotation.

Then, the rotation of the sun gear 51 input to the second planetary reduction gear 5 is greatly reduced by the stepped pinion gear 53, and then output to the differential case 60 in which the side plate portion 651 of the carrier 55 is integrally formed.

As shown in fig. 1, the differential case 60 is formed in a hollow shape in which a shaft 61, bevel gears 62A, 62B, and side gears 63A, 63B are housed.

In the differential case 60, tubular support portions 601 and 602 are provided on both sides in the rotation axis X direction (left and right direction in the drawing). The support portions 601 and 602 extend along the rotation axis X in a direction away from the shaft 61.

The inner race B2a of the bearing B2 is press-fitted into the outer periphery of the support portion 602. The outer race B2B of the bearing B2 is held by the annular support portion 131 of the housing 13, and the support portion 602 of the differential case 60 is rotatably supported by the housing 13 via a bearing B2.

The drive shaft 8A penetrating the opening 130 of the housing 13 is inserted into the support portion 602 from the rotation axis X direction, and the drive shaft 8A is rotatably supported by the support portion 602.

A lip seal RS is fixed to the inner periphery of the opening 130, and a lip portion, not shown, of the lip seal RS elastically contacts the outer periphery of the drive shaft 8A, thereby sealing a gap between the outer periphery of the drive shaft 8A and the inner periphery of the opening 130.

The drive shaft 8B penetrating the opening 114 of the cover 11 is inserted into the support portion 601 from the rotation axis X direction.

The drive shaft 8B is provided across the inner diameter sides of the motor shaft 20 of the motor 2, the sun gear 41 of the first planetary reduction gear 4, and the sun gear 41 of the second planetary reduction gear 5 in the direction of the rotation axis X, and the distal end side of the drive shaft 8B is rotatably supported by a support portion 601.

A lip seal RS is fixed to the inner periphery of the opening portion 114 of the cover 11, and a lip portion, not shown, of the lip seal RS elastically contacts the outer periphery of the drive shaft 8B, thereby sealing a gap between the outer periphery of the drive shaft 8B and the inner periphery of the opening portion 114.

In the differential case 60, side gears 63A and 63B are spline fitted to the outer peripheries of the distal end portions of the drive shafts 8A and 8B, and the side gears 63A and 63B are integrally rotatably coupled to the drive shafts 8(8A and 8B) about the rotation axis X.

In the differential case 60, shaft holes 60a and 60b penetrating in a direction perpendicular to the rotation axis X are provided at positions symmetrical with respect to the rotation axis X.

The shaft holes 60a and 60b are located on an axis Y perpendicular to the rotation axis X, and one end 61a side and the other end 61b side of the shaft 61 are inserted therein.

One end 61a side and the other end 61b side of the shaft 61 are fixed to the differential case 60 by a pin P, and the shaft 61 is inhibited from rotating around the axis Y.

The lower side of the differential case 60 is immersed in the lubricating oil in the housing 13.

In the present embodiment, when the one end 61a or the other end 61b of the shaft 61 is located on the lowermost side, the lubricating oil is retained in the housing 13 until the one end 61a or the other end 61b of the shaft 61 is located at least at the height in the lubricating oil.

The shaft 61 is located between the side gears 63A, 63B in the differential case 60 and is arranged along the axis Y.

In the differential case 60, bevel gears 62A, 62B are externally fitted and rotatably supported on a shaft 61.

The bevel gears 62A and 62B are provided at intervals of 2 in the longitudinal direction of the shaft 61 (the axial direction of the axis Y), and the bevel gears 62A and 62B are arranged with their tooth portions facing each other. On the shaft 61, bevel gears 62A, 62B are provided such that the axial centers of the bevel gears 62A, 62B coincide with the axial center of the shaft 61.

In the differential case 60, the side gears 63A, 63B are located on both sides of the bevel gears 62A, 62B in the direction of the rotation axis X.

The side gears 63A and 63B are provided in 2 pieces at intervals in the direction of the rotation axis X in a state where their respective teeth face each other, and the bevel gears 62A and 62B and the side gears 63A and 63B are assembled in a state where their respective teeth mesh with each other.

The operation of the power transmission device 1 having this configuration will be described.

In the power transmission device 1, provided along a transmission path of the output rotation of the electric motor 2 are: a reduction mechanism 3 (a first planetary reduction gear 4, a second planetary reduction gear 5), a differential device 6, and a drive shaft 8(8A, 8B).

When the rotor core 21 is rotated about the rotation axis X by driving of the motor 2, rotation is input to the sun gear 41 of the first planetary reduction gear 4 via the motor shaft 20 that rotates integrally with the rotor core 21.

In the first planetary reduction gear 4, the sun gear 41 serves as an input portion for the output rotation of the motor 2, and the carrier 45 supporting the pinion gear 43 serves as an output portion for the input rotation.

When the sun gear 41 is rotated about the rotation axis X by the output rotation of the motor 2, the pinion gear 43 meshed with the outer periphery of the sun gear 41 and the inner periphery of the ring gear 42 is rotated about the axis X1.

Here, the ring gear 42 is spline-fitted to the inner periphery of the intermediate housing 12 (fixed-side member) and is restricted from rotating relative to the intermediate housing 12.

Therefore, the pinion 43 revolves around the rotation axis X while rotating around the axis X1. Thereby, the carrier 45 (the side plates 451, 452) supporting the pinion gear 43 rotates around the rotation axis X at a rotation speed lower than the output rotation of the motor 2.

As described above, the coupling portion 453 of the carrier 45 is coupled to the coupling portion 511 of the sun gear 51 on the second planetary reduction gear 5 side, and the rotation of the carrier 45 (the output rotation of the first planetary reduction gear 4) is input to the sun gear 51 of the second planetary reduction gear 5.

The output portion (carrier 45) of the first planetary reduction gear 4 is coupled to the input portion (sun gear 51) of the second planetary reduction gear 5 without any other member such as a clutch or a transmission mechanism.

That is, the output portion (carrier 45) of the first planetary reduction gear 4 and the input portion (sun gear 51) of the second planetary reduction gear 5 rotate integrally (rotate integrally at all times).

Therefore, the distance between the first planetary reduction gear 4 and the second planetary reduction gear 5 can be made close to the amount by which only the other members are not on the power transmission path, and therefore, the axial shortening is facilitated.

In the second planetary reduction gear 5, the sun gear 51 serves as an input portion for the output rotation of the second planetary reduction gear 5, and the carrier 55 supporting the stepped pinion gear 53 serves as an output portion for the input rotation.

When the sun gear 51 rotates about the rotation axis X by the input rotation, the stepped pinions 53 (the large-diameter gear portion 531 and the small-diameter gear portion 532) rotate about the axis X2 by the rotation input from the sun gear 51 side.

Here, the small-diameter gear portion 532 of the stepped pinion 53 meshes with the ring gear 52 fixed to the inner periphery of the housing 13. Therefore, the stepped pinion 53 revolves around the rotation axis X while rotating around the axis X2.

Thereby, the carrier 55 (the side plate portions 551, 651) supporting the stepped pinion gears 53 rotates around the rotation axis X at a lower rotation speed than the rotation input from the first planetary reduction gear 4 side.

Here, in the stepped pinion 53, the outer diameter R2 of the small-diameter gear portion 532 is smaller than the outer diameter R1 of the large-diameter gear portion 531 (see fig. 2).

Therefore, the rotation of the sun gear 51 input to the second planetary reduction gear 5 is greatly reduced by the stepped pinion gear 53 as compared with the case of the first planetary reduction gear 4, and then output to the differential case 60 (differential device 6) in which the side plate portion 651 of the carrier 55 is integrally formed.

The rotation input to the differential gear box 60 is transmitted to left and right drive wheels (not shown) of the vehicle on which the power transmission device 1 is mounted via the drive shaft 8(8A, 8B).

In this way, the first planetary reduction gear 4 and the second planetary reduction gear 5 constituting the reduction mechanism 3 are arranged in series on the transmission path of the output rotation of the motor 2, and the pinion of the second planetary reduction gear 5 is made to be the stepped pinion 53.

Thus, in the single-shaft type power transmission device, the reduction ratio of the reduction mechanism 3 can be increased as compared with a case where planetary reduction gears having normal pinions (stepless pinions) are simply arranged in series.

(parking lock mechanism 7)

The parking lock mechanism 7 will be explained below.

Fig. 4 is a diagram illustrating the parking lock mechanism 7. Fig. 4(a) is a schematic view showing a section a-a in fig. 3. (b) Is a schematic view showing a cross section A-A in (a). For convenience of explanation, only a part of the side plate portion 451 is described.

The parking lock mechanism 7 is accommodated in the recess 129 of the intermediate case 12.

As shown in fig. 4(a) and (b), the parking lock mechanism 7 includes: a parking gear 71, a parking pawl 70, a parking lever 72, an auxiliary actuator 75, and a cam 76 formed on the side plate portion 451 of the carrier 45.

The parking pawl 70 has a plate-shaped base 701. The base 701 is supported by a support pin 702 at a substantially central portion in the longitudinal direction.

The support pin 702 is fixed to the intermediate cover 14 along the direction of the axis X3 parallel to the rotation axis X. The parking pawl 70 is rotatably supported by the intermediate cover 14 about the axis X3 by a support pin 702.

In this state, the parking pawl 70 overlaps the first planetary reduction gear 4 and the second planetary reduction gear 5 in the rotation axis X direction (see fig. 1).

The base 701 of the parking pawl 70 is provided across the axis X3 (in the left-right direction in fig. 4(a)) as viewed from the rotation axis X direction. The base 701 has an engagement portion 70a that engages with and disengages from the tooth groove portion 71a of the parking gear 71 on the side with the axis X3 therebetween. The base 701 has an operated portion 70b operated by the cam 76 of the parking lever 72 on the other side with respect to the axis X3.

When the parking pawl 70 rotates about the axis X3, the engagement portion 70a is displaced in the circumferential direction about the axis X3 and engages with and disengages from the tooth groove portion 71a of the parking gear 71 (see the imaginary line in the figure). When the engagement portion 70a engages with the tooth groove portion 71a, the rotation of the parking gear 71 (the carrier 45) is restricted. When the engaging portion 70a is disengaged from the tooth groove portion 71a, the rotation of the parking gear 71 (the carrier 45) is permitted.

A spring, not shown, is attached to the base 701. The parking pawl 70 is biased by a spring in a direction (clockwise direction of the axis X3) in which the engaging portion 70a is disengaged from the tooth groove portion 71 a.

When the parking lock mechanism 7 is not operated (when the vehicle is running), the parking pawl 70 holds the engaging portion 70a at a position disengaged from the notch portion 71a by the biasing force of the spring. In this state, the operated unit 70b abuts on the auxiliary actuator 75 (see fig. 4 (a)).

As shown in fig. 4(a), the auxiliary actuator 75 is provided above the support pin 702 of the parking pawl 70 in the vertical line VL direction with respect to the installation state of the power transmission device 1. The auxiliary actuator 75 is fixed to the intermediate cover 14.

The auxiliary actuator 75 has an arc-shaped cam surface 751 as viewed from the direction of the axis X3 at a portion facing the parking pawl 70 (operated portion 70 b).

The cam surface 751 is an inclined surface inclined in a direction approaching the operated portion 70b of the parking pawl 70 as it goes toward the front end side of the parking lever 72 (see fig. 4 (b)).

As shown in fig. 4 (b), the parking rod 72 is provided so as to be movable forward and backward in the direction of the axis X4 parallel to the axis X3. The forward and backward movement of the parking lever 72 is controlled by a hydraulic circuit of a valve body, not shown.

A stopper 74 is fixed to the front end of the parking rod 72 in the direction of the axis X4.

The cam 76 biased by the spring Sp abuts against the stopper 74 from the axis X3 direction.

When the parking lock mechanism 7 is operated (when the vehicle is parked), the parking lever 72 is held at a position where the cam 76 is inserted between the cam surface 751 of the assist actuator 75 and the operated portion 70 b.

When the parking lock mechanism 7 is not operated, the parking lever 72 is held at a position where the cam 76 is separated from between the cam surface 751 of the auxiliary actuator 75 and the operated portion 70 b.

In the parking lock mechanism 7, when the cam 76 is inserted between the cam surface 751 of the auxiliary actuator 75 and the operated portion 70b, the parking pawl 70 pressed by the cam 76 rotates counterclockwise about the axis X3 against the biasing force of the spring.

When the engaging portion 70a of the parking pawl 70 engages with the tooth groove portion 71a on the outer periphery of the parking gear 71, the rotation of the carrier 45 is restricted (see the imaginary line in fig. 4 a).

Here, when the parking lock mechanism 7 is operated (when the vehicle is parked), torque is input from the drive wheel side (the drive shaft 8, the differential device 6) to the parking lock mechanism 7.

In the present embodiment, the second planetary reduction gear 5 is interposed between the parking lock mechanism 7 and the drive wheels in the transmission path of the output rotation of the electric motor 2. Thus, when the parking lock mechanism 7 is operated (when the vehicle is parked), the torque input from the drive wheel side to the parking lock mechanism 7 is cancelled (reduced).

As described above, the power transmission device 1 of the present embodiment has the following configuration.

(1) Comprising: a first planetary reduction gear 4 (planetary gear);

a second planetary reduction gear 5 (reduction gear) connected downstream of the first planetary reduction gear 4;

a parking lock mechanism 7.

The parking lock mechanism 7 locks the carrier 45 (one of the rotating elements) of the first planetary reduction gear 4.

With this configuration, since a torque is input to the parking lock mechanism 7 from the output side (drive wheel side) via the second planetary reduction gear 5, the torque applied to the parking lock mechanism 7 is cancelled.

The power transmission device 1 of the present embodiment has the following configuration.

(2) The parking pawl 70, the first planetary reduction gear 4, and the second planetary reduction gear 5 of the parking lock mechanism 7 overlap in the rotation axis X direction.

With this configuration, the power transmission device 1 can be downsized in the radial direction of the rotation axis X.

The power transmission device 1 of the present embodiment has the following configuration.

(3) An intermediate cover 14 (a partition wall) is provided between the first planetary reduction gear 4 and the second planetary reduction gear 5,

the parking pawl 70 is rotatably supported by the intermediate cover 14.

As described above, by adopting the structure in which the partition wall is provided in the gear chamber, it is possible to facilitate the support of the parking pawl 70

The power transmission device 1 of the present embodiment has the following configuration.

(4) The parking lock mechanism 7 locks the outer peripheral side of the carrier 45 of the first planetary reduction gear 4.

With this configuration, the space between the side surface of the ring gear 42 and the outer diameter side of the carrier 45 is used, thereby suppressing an increase in size.

The power transmission device 1 of the present embodiment has the following configuration.

(5) The first planetary reduction gear 4 is connected downstream of the motor 2.

The motor 2 and the first planetary reduction gear 4 overlap in the rotation axis X direction.

With this configuration, the entire power transmission device 1 can be reduced in size in the radial direction of the rotation axis X.

(modification example)

Fig. 5 is a diagram illustrating a power transmission device 1A according to a modification.

Fig. 6 is a diagram illustrating a power transmission device 1A according to a modification, and is an enlarged view of the periphery of the transmission mechanism 3A and the counter gear 9 of the power transmission device 1A.

Fig. 7 is a diagram illustrating a power transmission device 1A according to a modification, and is an enlarged view of a region a in fig. 5.

In the following description, a description of a portion common to the power transmission device 1 of the present embodiment is omitted.

In the above embodiment, the case where the first planetary reduction gear 4 and the second planetary reduction gear 5 are disposed on the transmission path of the output rotation of the motor 2 is exemplified.

The present invention is not limited to this mode. For example, as shown in fig. 5, instead of the first planetary reduction gear 4 and the second planetary reduction gear 5, the speed change mechanism 3A and the counter gear 9 may be provided on a transmission path of the output rotation of the motor 2.

As shown in fig. 5, the power transmission device 1A includes: the electric motor 2, the transmission mechanism 3A, the counter gear 9 that transmits the output rotation of the transmission mechanism 3A to the differential device 6, and the differential device 6 that transmits the transmitted rotation to the drive shaft 8(8A, 8B).

In the power transmission device 1A, along a transmission path of the output rotation of the electric motor 2, there are provided: a transmission mechanism 3A, a counter gear 9, a differential device 6, and a drive shaft 8(8A, 8B).

The output rotation of the electric motor 2 is shifted by the transmission mechanism 3A, and then reduced in speed by the counter gear 9 and transmitted to the differential device 6. The rotation transmitted to the differential device 6 is transmitted to left and right drive wheels (not shown) of a vehicle on which the power transmission device 1A is mounted via drive shafts 8(8A, 8B).

Here, the transmission mechanism 3A is connected downstream of the electric motor 2, the counter gear 9 is connected downstream of the transmission mechanism 3A, the differential device 6 is connected downstream of the counter gear 9, and the drive shaft 8(8A, 8B) is connected downstream of the differential device 6.

In the power transmission device 1A of the modification, the motor case 10, the outer cover 11, the intermediate case 12A, the outer case 13, and the intermediate cover 14A constitute the main body case 9A of the power transmission device 1A.

The motor housing 10, the outer cover 11, and the intermediate case 12A constitute a case (first case member) of the motor 2.

The outer case 13 and the intermediate cover 14A constitute a case (second case member) that houses the counter gear 9 and the differential device 6.

Here, on the inner diameter side of the motor case 10, a space Sa formed between the outer cover 11 and the intermediate case 12A serves as a motor chamber for accommodating the motor 2.

As shown in fig. 6, a space formed between the outer case 13 and the intermediate cover 14A is divided by a partition wall 142 provided in the intermediate cover 14A into a space Sd for housing the counter gear 9 and the differential device 6 and a space Se for housing the transmission mechanism 3A.

Therefore, the space Sd serves as a first gear chamber for housing the counter gear 9 and the differential device 6, and the space Se serves as a second gear chamber for housing the transmission mechanism 3A.

As shown in fig. 5, the motor shaft 20A is a cylindrical member having an insertion hole 200 of the drive shaft 8B, and the motor shaft 20A is externally inserted to the drive shaft 8B.

In the insertion hole 200 of the motor shaft 20A, a coupling portion 201 on the one end 20A side in the longitudinal direction and a supported portion 202 on the other end 20b side are formed with an inner diameter larger than an intermediate region 203 between the coupling portion 201 and the supported portion 202 in the rotation axis X direction.

The inner periphery of the coupling portion 201 and the inner periphery of the supported portion 202 are supported by needle bearings NB, NB externally inserted in the drive shaft 8B.

In this state, the motor shaft 20A is provided to be rotatable relative to the drive shaft 8B.

In the motor shaft 20A, bearings B1 and B1 are fixed to the outer peripheries of the one end 20A side and the other end 20B side in the longitudinal direction by way of extrapolation.

The one end 20A side of the motor shaft 20A is rotatably supported by the cylindrical motor support portion 121 of the intermediate housing 12A via a bearing B1.

The other end 20B of the motor shaft 20A is rotatably supported by the cylindrical motor support portion 111 of the cover 11 via a bearing B1.

As shown in fig. 6, one end 20A of the motor shaft 20A penetrates the motor support portion 121 of the intermediate case 12A toward the transmission mechanism 3A (left side in the drawing) and is positioned in the space Se.

A lip seal RS is provided on the inner periphery of the motor support portion 121.

The lip seal RS seals a gap between the inner periphery of the motor bearing portion 121 and the outer periphery of the motor shaft 20A.

The lip seal RS is provided for partitioning a space Sa on the inner diameter side of the motor case 10 and a space Se on the inner diameter side of the intermediate cover 14A to prevent the oil OL from entering the space Sa from the space Se side.

As shown in fig. 7, the transmission mechanism 3A housed in the space Se includes: a planetary reduction gear 4A, a clutch 47, and a band brake 49.

The planetary reduction gear 4A has: sun gear 41, ring gear 42, pinion 43, pinion shaft 44, and planet carrier 45.

The constituent elements (the sun gear 41, the ring gear 42, the pinion gear 43, the pinion shaft 44, and the carrier 45) of the planetary reduction gear 4A are provided on the inner diameter side of the outer wall portion 481 of the clutch drum 48.

The clutch 47 has: a drive plate 471 (inner diameter side friction plate) spline-fitted to the outer periphery of the ring gear 42, a driven plate 472 (outer diameter side friction plate) spline-fitted to the inner periphery of the outer wall portion 481 of the clutch drum 48, and a piston 475 provided to be movable in the direction of the rotation axis X.

The clutch drum 48 has: an outer wall 481, a disk 480, an inner wall 482, and a coupling portion 483.

The outer wall 481 is cylindrical and surrounds the rotation axis X at a predetermined interval. The disc portion 480 extends radially inward from the end of the outer wall portion 481 on the differential device 6 side (right side in the drawing). The inner diameter side region of the circular plate portion 480 is a concave portion 480a that is recessed in a direction away from the planetary reduction gear 4A.

The inner wall portion 482 is formed in a cylindrical shape surrounding the rotation axis X at a predetermined interval. The inner wall portion 482 extends from the inner diameter side end of the disk portion 480 toward the planetary reduction gear 4A (right side in the figure), and the tip of the inner wall portion 482 faces the meshing portion between the sun gear 41 and the pinion gear 43 with a gap in the rotation axis X direction.

The connection portion 483 is cylindrical and surrounds the rotation axis X at a predetermined interval. A base end portion 483a in the longitudinal direction of the connection portion 483 is connected to the inner circumference of the front end side of the inner wall portion 482.

The connection portion 483 linearly extends in a direction approaching the motor 2 (rightward in the drawing) on an extension line of the connection portion 201 of the motor shaft 20. The front end 483b of the coupling portion 483 is located closer to the motor 2 than the outer wall portion 481.

The clutch drum 48 including the outer wall portion 481, the disk portion 480, the inner wall portion 482, and the coupling portion 483 is opened toward the motor 2 side, and the sun gear 41 of the planetary reduction gear 4A is spline-fitted to the outer periphery of the coupling portion 483 located on the inner diameter side.

In the planetary reduction gear 4A, the ring gear 42 is located on the outer diameter side of the sun gear 41. The ring gear 42 has: a peripheral wall portion 421 surrounding the outer periphery of the sun gear 41 at a predetermined interval, a disk portion 422 extending from the end portion of the peripheral wall portion 421 on the motor 2 side toward the inner diameter side, and a coupling portion 423 extending from the end portion of the disk portion 422 on the inner diameter side toward the motor 2 side.

The coupling portion 423 is annular surrounding the rotation axis X at a predetermined interval, and a coupling portion 201 on the one end 20a side of the motor shaft 20 is spline-fitted to the inner periphery of the coupling portion 423.

In the peripheral wall 421 located on the outer diameter side of the coupling portion 423, the outer periphery of the pinion gear 43 meshes with the inner periphery of the region located on the outer diameter side of the sun gear 41.

The pinion gear 43 meshes with the inner periphery of the peripheral wall portion 421 on the ring gear 42 side and the outer periphery of the sun gear 41.

The pinion shaft 44 supporting the pinion 43 is provided along the direction of the axis X5 parallel to the rotation axis X. One end and the other end of the pinion shaft 44 are supported by a pair of side plate sections 451, 452 constituting the planetary carrier 45.

The side plate portions 451, 452 are provided in parallel to each other with a gap in the direction of the axis X5.

One side plate portion 452 located on the motor 2 side extends radially inward of the rotation axis X than the other side plate portion 451. A tubular coupling portion 453 surrounding the rotation axis X at a predetermined interval is integrally formed at an end 452a on the inner diameter side of the side plate portion 452.

The coupling portion 453 extends further toward the rotation axis X (inner diameter side) than the coupling portion 201 of the motor shaft 20 along the rotation axis X in a direction away from the motor 2.

The coupling portion 453 is provided across the inner diameter side of the sun gear 41 from the motor 2 side to the differential device 6 side (left side in the figure), and the coupling portion 453 is spline-fitted to the inner periphery of the coupling portion 901 of the hollow shaft 90 on the inner diameter side of the inner wall portion 482 of the clutch drum 48.

The driven plate 472 of the clutch 47 is spline-fitted to the inner periphery of the outer wall portion 481 of the clutch drum 48. The drive disk 471 of the clutch 47 is spline-fitted to the outer periphery of the peripheral wall portion 421 of the ring gear 42.

The driving disk 471 and the driven disk 472 are alternately disposed between the peripheral wall portion 421 of the ring gear 42 and the outer wall portion 481 of the clutch drum 48.

The holding plate 473 positioned by the snap ring 474 is located on the motor 2 side of the area where the driving disc 471 and the driven disc 472 are alternately arranged, and the pressing portion 475a of the piston 475 is located on the differential device 6 side.

The base 475b on the inner diameter side of the piston 475 is provided at a position farther from the planetary reduction gear 4A than the pressing portion 475a on the outer diameter side. The base 475b on the inner diameter side of the piston 475 is inserted into the recess 480a on the inner diameter side of the disk 480 adjacent in the rotation axis X direction.

A spring Sp supported by the spring holder 476 is pressed against a surface of the base 475b on the motor 2 side (left side in the drawing) from the rotation axis X direction.

The piston 475 is biased toward the differential device 6 by the biasing force applied from the spring Sp.

The clutch drum 48 is provided with a projection 484 projecting toward the differential device 6 side at a boundary between the recess 480a and the inner wall 482. The protruding portion 484 is inserted into the inner periphery of the first supporting portion 141 of the bearing B3. The first support portion 141 is provided on the inner diameter side of the partition wall 142. A supply passage 141a for the oil OL opens on the inner periphery of the first support portion 141.

An oil passage 484a for guiding the oil OL supplied from the first support portion 141 side into the recess 480a of the clutch drum 48 is provided inside the projecting portion 484.

The oil OL supplied through the oil passage 484a is supplied to an oil chamber between the base 475b of the piston 475 and the recess 480a, and displaces the piston 475 toward the motor 2.

When the piston 475 is displaced toward the motor 2, the driving disc 471 and the driven disc 472 of the clutch 47 are gripped between the pressing portion 475a of the piston 475 and the holding plate 473.

Thereby, the relative rotation between the ring gear 42 spline-fitted to the drive plate 471 and the clutch drum 48 spline-fitted to the driven plate 472 is restricted by the pressure of the supplied oil OL, and the final relative rotation is restricted.

Further, a band brake 49 is wound around the outer periphery of the outer wall 481 of the clutch drum 48. When the winding radius of the band brake 49 is narrowed by an actuator not shown, the rotation of the clutch drum 48 about the rotation axis X is restricted.

In the transmission mechanism 3A, the planetary reduction gear 4A and the clutch 47 are located on the inner diameter side of the band brake 49. The band brake 49, the planetary reduction gear 4A, and the clutch 47 are overlapped in the radial direction of the rotation axis X, and the band brake 49, the planetary reduction gear 4A, and the clutch 47 are disposed in an overlapping positional relationship as viewed from the radially outer side of the rotation axis X.

In the transmission mechanism 3A, the ring gear 42 of the planetary reduction gear 4A serves as an input portion for the output rotation of the motor 2, and the carrier 45 serves as an output portion for the input rotation.

Specifically, the output rotation of the motor 2 is output to the hollow shaft 90 of the coupling portion 453 of the planetary carrier 45 after being shifted by the speed change mechanism 3A.

As shown in fig. 6, one end 90a in the longitudinal direction of the hollow shaft 90 to which the rotation after the speed change by the speed change mechanism 3A is input is provided with a gap in the rotation axis X direction from the bearing B5 that supports the support portion 601 of the differential case 60. The other end 90b of the hollow shaft 90 serves as a coupling portion 901 with the planetary reduction gear 4A.

The outer periphery of the coupling portion 901 is supported by a needle bearing NB interposed between the coupling portion and the inner wall 482 of the clutch drum 48. A parking gear 71 is provided between a region of the coupling portion 901 supported by the needle bearing NB and a region supported by a bearing B3 described later.

Here, as shown in fig. 7, a recess 149 is formed in the first support portion 141 of the intermediate cover 14A at a position facing the parking gear 71. The concave portion 149 is formed below the rotation axis X in the vertical line VL direction in the installed state of the power transmission device 1A.

The parking lock mechanism 7 is accommodated in the recess 149.

In the parking lock mechanism 7 of the power transmission device 1A, the parking pawl 70 is rotatably supported about the axis X3 by the support pin 702 (see fig. 4).

In this case, the support pin 702 may be provided on either one of the side wall of the recess 149 on the motor 2 side or the side wall of the differential device 6 side.

The parking lock mechanism 7 of the power transmission device 1A according to the modification has the same configuration as that of the present embodiment, and therefore, a detailed description thereof is omitted.

In the parking lock mechanism 7 of the power transmission device 1A, when the engagement portion 70a of the parking pawl 70 engages with the tooth groove portion 71A on the outer periphery of the parking gear 71, the rotation of the connection portion 901 (hollow shaft 90) is restricted. Thereby, the rotation of the coupling portion 453 (the planetary carrier 45) spline-fitted to the inner periphery of the coupling portion 901 is regulated. That is, the parking lock mechanism 7 locks the carrier 45, which is one of the rotary elements of the planetary reduction gear 4A.

As shown in fig. 6, a gear portion 902 is integrally formed on the outer periphery of the hollow shaft 90 on the one end 90a side. Bearings B3 and B3 are externally inserted on both sides of the gear portion 902.

The bearing B3 on the one end 90a side is supported by the support 151 on the outer case 13 side, and the bearing B3 on the other end 90B side is supported by the first support portion 141 of the intermediate cover 14A.

The large diameter gear 92 of the counter gear 9 is rotatably engaged with the outer periphery of the gear portion 902. In the counter gear 9, a large-diameter gear 92 is spline-fitted to the outer periphery of the cylindrical hollow shaft portion 91.

Bearings B4 and B4 are respectively inserted and fitted into one end 91a and the other end 91B of the hollow shaft 91 in the longitudinal direction. The bearing B4 externally inserted into the one end 91a of the hollow shaft 91 is inserted into the cylindrical second support portion 135 of the outer housing 13. One end portion 91a of the hollow shaft portion 91 is rotatably supported by the second support portion 135 of the outer case 13 via a bearing B4.

The bearing B4 externally inserted into the other end 91B of the hollow shaft 91 is inserted into the cylindrical second support portion 145 of the intermediate cover 14A. The other end portion 91B of the hollow shaft portion 91 is rotatably supported by the second support portion 145 of the intermediate cover 14A via a bearing B4.

In this state, the hollow shaft portion 91 of the counter gear 9 is provided along the axis X9 parallel to the rotation axis X.

The hollow shaft portion 91 is provided with a small-diameter gear portion 911 on the side of the one end portion 91a (left side in the drawing). The small-diameter gear portion 911 is formed integrally with the hollow shaft portion 91, and is formed with an outer diameter R4 smaller than the outer diameter R3 of the large-diameter gear 92.

The small-diameter gear portion 911 is rotatably engaged with a final gear FG fixed to the differential case 60 of the differential device 6.

In the power transmission device 1A, the output rotation of the motor 2 is input to the counter gear 9 via the speed change mechanism 3A and the hollow shaft 90, and via the large diameter gear 92 meshing with the gear portion 902 of the hollow shaft 90.

In the counter gear 9, a large-diameter gear 92 is spline-fitted to the outer periphery of the hollow shaft portion 91, and a small-diameter gear portion 911 is formed integrally with the hollow shaft portion 91.

Therefore, when the output rotation of the motor 2 is input to the counter gear 9, the small-diameter gear portion 911 rotates about the axis X9 together with the large-diameter gear 92.

Then, since the final gear FG in which the small-diameter gear portion 911 is engaged so as to be able to transmit rotation is fixed to the differential case 60, the differential case 60 rotates about the rotation axis X in conjunction with the rotation of the counter gear 9 about the axis X9.

Here, in the counter gear 9, the outer diameter R4 of the small-diameter gear portion 911 is smaller than the outer diameter R3 of the large-diameter gear 92 (see fig. 6).

In the counter gear 9, the large-diameter gear 92 serves as an input portion of the rotation transmitted from the motor 2 side, and the small-diameter gear portion 911 serves as an output portion of the transmitted rotation.

Then, the rotation input to the counter gear 9 is greatly reduced and then output to the differential gear box 60.

As shown in fig. 6, a bearing B5 is externally fitted to the support portion 601 of the differential case 60.

The support portion 601 of the differential case 60 is rotatably supported by the support portion 151 of the support member 15 fixed to the outer case 13 via a bearing B5.

The bearing B5 externally inserted into the support portion 601 is held by the annular support portion 151 of the support member 15.

As shown in fig. 5, the support member 15 includes: a cylindrical portion 152 extending from the outer periphery of the support portion 151 toward the motor 2 (right side in the figure), and a flange portion 153 surrounding the opening at the distal end side of the cylindrical portion 152 over the entire circumference. The flange 153 of the support member 15 is fixed to the first support portion 141 of the intermediate cover 14A by a bolt B penetrating the flange 153.

The support portion 601 of the differential case 60 is rotatably supported by the support member 15 via a bearing B5. In the present embodiment, the support member 15 is fixed to the intermediate cover 14A. Therefore, the support portion 601 of the differential case 60 is supported by the intermediate cover 14A as a stationary member via the bearing B5 and the support member 15.

As shown in fig. 5, the drive shaft 8B penetrating the opening 114 of the outer cover 11 is inserted into the support portion 601 of the differential case 60 from the rotation axis X direction.

The drive shaft 8B is provided across the motor shaft 20A of the motor 2, the planetary reduction gear 4A, and the inner diameter side of the hollow shaft 90 in the direction of the rotation axis X, and the distal end side of the drive shaft 8B is rotatably supported by a support portion 601.

In the differential case 60, side gears 63A and 63B are spline-fitted to the outer peripheries of the distal end portions of the drive shafts 8(8A and 8B), and the side gears 63A and 63B and the drive shafts 8(8A and 8B) are integrally rotatably coupled around a rotation axis X.

When the parking lock mechanism 7 is operated (when the vehicle is parked), torque is input from the drive wheel side (the drive shaft 8, the differential device 6) to the parking lock mechanism 7.

In the power transmission device 1A, the counter gear 9 is interposed between the parking lock mechanism 7 and the drive wheels in the transmission path of the output rotation of the electric motor 2. Thus, when the parking lock mechanism 7 is operated (when the vehicle is parked), the torque input from the drive wheel side to the parking lock mechanism 7 is cancelled (reduced).

As described above, the power transmission device 1A of the modification has the following configuration.

(6) Comprising: a planetary reduction gear 4A (planetary gear);

a counter gear 9 (reduction gear) connected downstream of the planetary reduction gear 4A;

a parking lock mechanism 7.

The parking lock mechanism 7 locks a carrier 45 (one of the rotating elements) of the planetary reduction gear 4A.

With this configuration, since torque is input to the locking mechanism 7 from the output side (drive wheel side) via the counter gear 9, the torque applied to the locking mechanism 7 is cancelled out.

The power transmission device 1A of the modification has the following configuration.

(7) The planetary reduction gear 4A is connected downstream of the motor 2.

The motor 2 and the planetary reduction gear 4A overlap in the direction of the rotation axis X.

With this configuration, the entire power transmission device 1A can be reduced in size in the radial direction of the rotation axis X.

Here, the term "connected to the downstream" in the present specification means a connection relationship in which power is transmitted from a member disposed upstream to a member disposed downstream.

For example, when the first planetary reduction gear 4 connected to the downstream side of the motor 2 is referred to, the power is transmitted from the motor 2 to the first planetary reduction gear 4.

The term "directly connected" in the present specification means that members for changing the reduction ratio are connected to each other so as to be capable of transmitting power without passing through other members for changing the reduction ratio such as a speed reducing mechanism, a speed increasing mechanism, and a speed changing mechanism.

The embodiments of the present invention have been described above, but the present invention is not limited to the embodiments shown in the embodiments. The present invention can be modified as appropriate within the scope of the technical idea of the invention.