Power transmission device

Abstract

To increase flexibility in lubrication design.SOLUTION: A power transmission device includes: a differential mechanism; a case for accommodating the differential mechanism; and a pinion gear supported to the case, in a box. The box includes a shelf portion upward from a horizontal line that passes through the revolution center of the pinion gear.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power transmission device.

Background Art

[0002] Patent Document 1 discloses a power transmission device for an electric vehicle having a bevel gear differential mechanism and a planetary gear mechanism. The planetary gear mechanism of Patent Document 1 includes a stepped pinion gear having a large pinion gear and a small pinion gear.

Prior Art Documents

[0006] According to one aspect of the present invention, a power transmission device with a structure that offers a high degree of freedom in lubrication design can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] This is a skeletal diagram of the power transmission system. [Figure 2] This is a schematic diagram of a cross-section of a power transmission device. [Figure 3] This is a magnified view of the planetary reduction gear area of ​​the power transmission system. [Figure 4] This is a magnified view of the differential mechanism area of ​​the power transmission system. [Figure 5] This is a perspective view of the differential mechanism of a power transmission system. [Figure 6] This is an exploded perspective view of the differential mechanism of a power transmission system. [Figure 7] This is a diagram illustrating the first case section of the differential mechanism. [Figure 8] This is a diagram illustrating the first case section of the differential mechanism. [Figure 9] This is a diagram illustrating the first case section of the differential mechanism. [Figure 10] It is a diagram for explaining the first case part of the differential mechanism. [Figure 11] It is a diagram for explaining the second case part of the differential mechanism. [Figure 12] It is a diagram for explaining the second case part of the differential mechanism. [Figure 13] It is a diagram for explaining the second case part of the differential mechanism. [Figure 14] It is a diagram for explaining the second case part of the differential mechanism. [Figure 15] It is a diagram for explaining the second case part of the differential mechanism. [Figure 16] It is a diagram for explaining the second case part of the differential mechanism. [Figure 17] It is a diagram for explaining the oil catch part. [Figure 18] It is a diagram for explaining the oil catch part. [Figure 19] It is a diagram for explaining the oil catch part. [Figure 20] It is a diagram for explaining the oil catch part. [Figure 21] It is a diagram for explaining the oil catch part. [Figure 22] It is a diagram for explaining the oil catch part. <9000106> [Figure 23] It is a diagram for explaining the oil catch part. [Figure 24] It is a diagram for explaining the oil catch part. <9000110> [Figure 25] It is a diagram for explaining the oil catch part. e =

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described. FIG. 1 is a skeleton diagram for explaining the power transmission device 1 according to the present embodiment. FIG. 2 is a schematic cross-sectional view for explaining the power transmission device 1 according to the present embodiment. FIG. 3 is an enlarged view around the planetary reduction gear 4 of the power transmission device 1. Figure 4 is an enlarged view of the differential mechanism 5 of the power transmission device 1.

[0009] As shown in Figure 1, the power transmission device 1 includes a motor 2 and a planetary reduction gear 4 (reduction mechanism) that reduces the output rotation of the motor 2 and inputs it to the differential mechanism 5. The power transmission device 1 also includes a drive shaft 9 (9A, 9B) as a drive shaft and a park lock mechanism 3. In the power transmission device 1, a park lock mechanism 3, a planetary reduction gear 4, a differential mechanism 5, and drive shafts 9 (9A, 9B) are provided along the transmission path of the output rotation around the rotation axis X of the motor 2. The axes of the drive shafts 9 (9A, 9B) are coaxial with the rotation axis X of the motor 2.

[0010] In the power transmission device 1, the output rotation of the motor 2 is reduced by the planetary reduction gear 4 and input to the differential mechanism 5, and then transmitted via the drive shafts 9 (9A, 9B) to the left and right drive wheels W, W of the vehicle on which the power transmission device 1 is mounted. Here, the planetary reduction gear 4 is connected downstream of the motor 2, the differential mechanism 5 is connected downstream of the planetary reduction gear 4, and the drive shafts 9 (9A, 9B) are connected downstream of the differential mechanism 5.

[0011] As shown in Figure 2, the main body box 10 of the power transmission device 1 includes a first box 11 that houses the motor 2, and a second box 12 that is fitted onto the first box 11. The main body box 10 also includes a third box 13 that is assembled to the first box 11, and a fourth box 14 (box) that is assembled to the second box 12.

[0012] The first box 11 has a cylindrical support wall portion 111 and a flange-shaped joint portion 112 provided at one end 111a of the support wall portion 111. The first box 11 is provided with its support wall portion 111 oriented along the rotation axis X of the motor 2. The motor 2 is housed inside the support wall portion 111.

[0013] The joint portion 112 is provided in a direction perpendicular to the rotation axis X. The joint portion 112 is formed with a larger outer diameter than the support wall portion 111.

[0014] The second box 12 has a cylindrical peripheral wall portion 121, a flange-shaped joint portion 122 provided at one end 121a of the peripheral wall portion 121, and a flange-shaped joint portion 123 provided at the other end 121b of the peripheral wall portion 121. The peripheral wall portion 121 is formed with an inner diameter that allows it to be externally fitted onto the support wall portion 111 of the first box 11. The first box 11 and the second box 12 are assembled together by extrapolating the peripheral wall portion 121 of the second box 12 onto the support wall portion 111 of the first box 11.

[0015] The joint portion 122 on one end 121a of the peripheral wall portion 121 abuts against the joint portion 112 of the first box 11 from the direction of the rotation axis X. These joint portions 122 and 112 are connected to each other by bolts (not shown). In the first box 11, a plurality of grooves 111b are provided on the outer circumference of the support wall portion 111. The plurality of grooves 111b are provided at intervals in the direction of the rotation axis X. Each of the grooves 111b is provided around the entire circumference in the circumferential direction around the rotation axis X. The peripheral wall portion 121 of the second box 12 is fitted onto the support wall portion 111 of the first box 11. The opening of the groove 111b is closed by the peripheral wall portion 121. Multiple cooling passages CP through which cooling water flows are formed between the support wall portion 111 and the peripheral wall portion 121.

[0016] On the outer circumference of the support wall portion 111 of the first box 11, ring grooves 111c, 111c are formed on both sides of the area where the recessed groove 111b is provided. Seal rings 113, 113 are fitted and attached to the ring grooves 111c, 111c. These sealing rings 113 press against the inner circumference of the peripheral wall portion 121 which is fitted onto the support wall portion 111, thereby sealing the gap between the outer circumference of the support wall portion 111 and the inner circumference of the peripheral wall portion 121.

[0017] The other end 121b of the second box 12 is provided with a wall portion 120 extending inward. The wall portion 120 is oriented perpendicular to the rotation axis X. An opening 120a is provided in the region of the wall portion 120 that intersects with the rotation axis X, through which the drive shaft 9A is inserted. In the wall section 120, a cylindrical motor support section 125 is provided on the motor 2 side (right side in the figure) that surrounds the opening 120a. The motor support portion 125 is inserted inside the coil end 253b, which will be described later. The motor support portion 125 faces the end portion 21b of the rotor core 21 with a gap in the direction of the rotation axis X.

[0018] The peripheral wall portion 121 of the second box 12 has a radial thickness greater in the lower region in the vertical direction, relative to the state in which the power transmission device 1 is mounted on the vehicle, than in the upper region. In this region with greater radial thickness, an oil reservoir 128 is provided, penetrating in the direction of the rotation axis X. The oil reservoir 128 is connected to an axial oil passage 138 provided in the joint 132 of the third box 13 via a communication hole 112a. The communication hole 112a is provided in the joint 112 of the first box 11.

[0019] The third box 13 has a wall portion 130 perpendicular to the rotation axis X. A ring-shaped joint portion 132 is provided on the outer circumference of the wall portion 130 when viewed from the direction of the rotation axis X. The third box 13 is located on the opposite side (right side in the figure) from the differential mechanism 5 when viewed from the first box 11. The joint 132 of the third box 13 is joined to the joint 112 of the first box 11 from the direction of the rotation axis X. The third box 13 and the first box 11 are connected to each other by bolts (not shown). In this state, the opening on the joint 122 side (right side in the figure) of the support wall portion 111 of the first box 11 is blocked by the third box 13.

[0020] In the third box 13, a through hole 130a for the drive shaft 9A is provided in the center of the wall portion 130. A lip seal RS is provided on the inner circumference of the through hole 130a. The lip seal RS has a lip portion (not shown) that elastically contacts the outer circumference of the drive shaft 9A. The gap between the inner circumference of the through hole 130a and the outer circumference of the drive shaft 9A is sealed by the lip seal RS. On the side of the wall portion 130 facing the first box 11 (left side in the figure), a peripheral wall portion 131 is provided that surrounds the insertion hole 130a. The drive shaft 9A is supported on the inner circumference of the peripheral wall portion 131 via a bearing B4.

[0021] A motor support portion 135 is provided on the motor 2 side (left side in the figure) when viewed from the peripheral wall portion 131. The motor support portion 135 is cylindrical in shape and surrounds the rotating shaft X at intervals. A cylindrical connecting wall 136 is connected to the outer circumference of the motor support portion 135. The connecting wall 136 has a larger outer diameter than the peripheral wall portion 131 on the wall portion 130 side (right side in the figure). The connecting wall 136 is provided in a direction along the rotation axis X and extends away from the motor 2. The connecting wall 136 connects the motor support portion 135 to the wall portion 130 of the third box 13.

[0022] The motor support portion 135 is supported by the third box 13 via a connecting wall 136. One end 20a of the motor shaft 20 penetrates the inside of the motor support portion 135 from the motor 2 side to the peripheral wall portion 131 side. A bearing B1 is supported on the inner circumference of the motor support portion 135. The outer circumference of the motor shaft 20 is supported by the motor support portion 135 via the bearing B1. A lip seal RS is provided adjacent to bearing B1.

[0023] In the third box 13, an oil hole 136a, described later, is opened on the inner circumference of the connecting wall 136. Oil OL flows into the space enclosed by the connecting wall 136 (internal space Sc) from the oil hole 136a. The lip seal RS is provided to prevent oil OL inside the connecting wall 136 from flowing into the motor 2 side.

[0024] The fourth box 14 has a peripheral wall portion 141 that surrounds the outer circumference of the planetary reduction gear 4 and the differential mechanism 5, and a flange-shaped joint portion 142 provided at the end of the peripheral wall portion 141 on the side of the second box 12. The fourth box 14 is located on the differential mechanism 5 side (left side in the figure) when viewed from the second box 12. The joint 142 of the fourth box 14 is joined to the joint 123 of the second box 12 from the direction of the rotation axis X. The fourth box 14 and the second box 12 are connected to each other by bolts (not shown).

[0025] Inside the main box 10 of the power transmission device 1, there is a motor chamber Sa that houses the motor 2 and a gear chamber Sb that houses the planetary reduction gear 4 and the differential mechanism 5. The motor chamber Sa is formed inside the first box 11, between the wall portion 120 of the second box 12 and the wall portion 130 of the third box 13. The gear chamber Sb is formed on the inner diameter side of the fourth box 14, between the wall portion 120 of the second box 12 and the peripheral wall portion 141 of the fourth box 14.

[0026] A plate member 8 is provided inside the gear chamber Sb. The plate member 8 is fixed to the fourth box 14. The plate member 8 divides the gear chamber Sb into a first gear chamber Sb1 that houses the planetary reduction gear 4 and the differential mechanism 5, and a second gear chamber Sb2 that houses the park lock mechanism 3. In the direction of the rotation axis X, the second gear chamber Sb2 is located between the first gear chamber Sb1 and the motor chamber Sa.

[0027] The motor 2 comprises a cylindrical motor shaft 20, a cylindrical rotor core 21 fitted onto the motor shaft 20, and a stator core 25 that surrounds the outer circumference of the rotor core 21 at intervals.

[0028] On the motor shaft 20, bearings B1, B1 are externally fitted and fixed to both sides of the rotor core 21. Bearing B1 located at one end 20a (right side in the diagram) of the motor shaft 20 as viewed from the rotor core 21 is supported on the inner circumference of the motor support portion 135 of the third box 13. Bearing B1 located at the other end 20b is supported on the inner circumference of the cylindrical motor support portion 125 of the second box 12.

[0029] The motor support sections 135 and 125 are positioned on the inner diameter side of the coil ends 253a and 253b, which will be described later, opposite one end 21a and the other end 21b of the rotor core 21, with a gap in the direction of the rotation axis X.

[0030] The rotor core 21 is formed by laminating multiple silicon steel sheets. Each silicon steel sheet is extrapolated onto the motor shaft 20 in a manner that restricts its relative rotation to the motor shaft 20. When viewed from the direction of the rotation axis X of the motor shaft 20, the silicon steel plate forms a ring shape. On the outer circumference of the silicon steel plate, magnets with north poles and south poles (not shown) are alternately arranged in the circumferential direction around the rotation axis X.

[0031] The stator core 25, which surrounds the outer circumference of the rotor core 21, is formed by laminating multiple electromagnetic steel sheets. The stator core 25 is fixed to the inner circumference of the cylindrical support wall portion 111 of the first box 11. Each electrical steel sheet has a ring-shaped yoke portion 251 fixed to the inner circumference of the support wall portion 111, and a teeth portion 252 that protrudes from the inner circumference of the yoke portion 251 toward the rotor core 21.

[0032] In this embodiment, a stator core 25 is employed in which the winding 253 is distributed-wound across multiple tooth sections 252. The stator core 25 is longer in the direction of the rotation axis X than the rotor core 21 by the amount of the coil ends 253a and 253b that protrude in the direction of the rotation axis X.

[0033] Alternatively, a stator core may be used in which windings are concentrated on each of the multiple teeth 252 protruding from the rotor core 21.

[0034] An opening 120a is provided in the wall portion 120 (motor support portion 125) of the second box 12. The other end 20b of the motor shaft 20 passes through the opening 120a to the differential mechanism 5 side (left side in the figure) and is located inside the fourth box 14. The other end 20b of the motor shaft 20 faces the side gear 54A (described later) inside the fourth box 14, with a gap in the direction of the rotation axis X.

[0035] As shown in Figure 3, the motor shaft 20 has a stepped portion 201 in the region located within the fourth box 14. The stepped portion 201 is located near the motor support portion 125. A lip seal RS, supported on the inner circumference of the motor support portion 125, is in contact with the outer circumference of the region between the stepped portion 201 and the bearing B1. The lip seal RS separates the motor chamber Sa, which houses the motor 2, from the gear chamber Sb in the fourth box 14.

[0036] The inner diameter side of the fourth box 14 is filled with oil OL for lubricating the planetary reduction gear 4 and the differential mechanism 5 (see Figure 2). The lip seal RS is provided to prevent oil OL from flowing into the motor chamber Sa.

[0037] As shown in Figure 3, in the motor shaft 20, the region from the stepped portion 201 to the vicinity of the other end 20b is a fitting portion 202 with splines on its outer circumference. The park gear 30 and sun gear 41 are spline-fitted to the outer circumference of the mating portion 202.

[0038] One side of the park gear 30 in the direction of the rotation axis X is in contact with the stepped portion 201 (right side in the figure). One end 410a of the cylindrical base 410 of the sun gear 41 is in contact with the other side of the park gear 30 (left side in the figure). A nut N, which is screwed onto the other end 20b of the motor shaft 20, is pressed against the other end 410b of the base 410 from the direction of the rotation axis X. The sun gear 41 and the park gear 30 are sandwiched between the nut N and the stepped portion 201, and are positioned so as to be unable to rotate relative to the motor shaft 20.

[0039] The sun gear 41 has teeth 411 on the outer circumference of the other end 20b of the motor shaft 20. The large-diameter gear portion 431 of the stepped pinion gear 43 meshes with the outer circumference of the teeth 411.

[0040] The stepped pinion gear 43 (pinion gear) has a large-diameter gear portion 431 that meshes with the sun gear 41, and a small-diameter gear portion 432 that is smaller in diameter than the large-diameter gear portion 431. The stepped pinion gear 43 is a gear component in which a large-diameter gear section 431 and a small-diameter gear section 432 are arranged in the direction of an axis X1 parallel to the rotation axis X and are integrally mounted. The large-diameter gear section 431 is formed with an outer diameter R1 that is larger than the outer diameter R2 of the small-diameter gear section 432. The stepped pinion gear 43 is positioned along the axis X1. In this configuration, the large-diameter gear section 431 is located on the motor 2 side (right side in the diagram).

[0041] The outer circumference of the small-diameter gear section 432 meshes with the inner circumference of the ring gear 42. The ring gear 42 is ring-shaped, surrounding the rotating shaft X at intervals. The outer circumference of the ring gear 42 is provided with a plurality of engaging teeth 421 that protrude radially outward. The plurality of engaging teeth 421 are provided at predetermined intervals in the circumferential direction around the rotating shaft X. The ring gear 42 has engaging teeth 421 on its outer circumference that are spline-fitted to teeth 146a on the support wall 146 of the fourth box 14. The rotation of the ring gear 42 around the rotation axis X is restricted by its engagement with the support wall 146, which serves as the ring gear support.

[0042] The stepped pinion gear 43 has a through hole 430 that penetrates the inner diameter side of the large-diameter gear portion 431 and the small-diameter gear portion 432 in the direction of the axis X1. The stepped pinion gear 43 is rotatably supported on the outer circumference of the pinion shaft 44, which passes through the through hole 430, via needle bearings NB, NB.

[0043] On the outer circumference of the pinion shaft 44, an intermediate spacer MS is interposed between the needle bearing NB that supports the inner circumference of the large-diameter gear section 431 and the needle bearing NB that supports the inner circumference of the small-diameter gear section 432.

[0044] As shown in Figure 4, an internal oil passage 440 is provided inside the pinion shaft 44. The internal oil passage 440 runs along the axis X1 from one end 44a to the other end 44b of the pinion shaft 44. The pinion shaft 44 is provided with oil holes 442 and 443 that connect the internal oil passage 440 to the outer circumference of the pinion shaft 44.

[0045] The oil hole 443 opens into the region where the needle bearing NB supporting the inner circumference of the large-diameter gear section 431 is provided. The oil hole 442 opens into the region where the needle bearing NB, which supports the inner circumference of the small-diameter gear section 432, is provided. In the pinion shaft 44, the oil holes 443 and 442 open within the region in which the stepped pinion gear 43 is extrapolated.

[0046] Furthermore, the pinion shaft 44 is provided with an introduction passage 441 for introducing oil OL into the internal oil passage 440. On the outer circumference of the pinion shaft 44, the introduction passage 441 opens into a region located within the support hole 71a of the second case portion 7, which will be described later. The introduction passage 441 connects the internal shaft oil passage 440 with the outer circumference of the pinion shaft 44.

[0047] An internal case oil passage 781 opens on the inner circumference of the support hole 71a. The internal case oil passage 781 connects the inner circumference of the guide portion 78 protruding from the base portion 71 of the second case portion 7 with the inner circumference of the support hole 71a. In a cross-sectional view along axis X1, the internal oil passage 781 of the case is inclined with respect to axis X1. The internal oil passage 781 is inclined in a direction that approaches the slit 710 provided in the base 71 as it moves toward the rotation axis X.

[0048] Oil OL, which is scraped up by the differential case 50 as described later, flows into the oil passage 781 inside the case. Oil OL that moves towards the outer diameter side due to the centrifugal force caused by the rotation of the differential case 50 also flows into the oil passage 781 inside the case. Oil OL that flows from the case internal oil passage 781 into the introduction passage 441 flows into the internal oil passage 440 of the pinion shaft 44. Oil OL that flows into the internal oil passage 440 is discharged radially outward from the oil holes 442 and 443. Oil OL discharged from the oil holes 442 and 443 lubricates the needle bearing NB that is fitted onto the pinion shaft 44.

[0049] In the pinion shaft 44, a through hole 444 is provided on the other end 44b side of the region where the introduction passage 441 is provided. The through hole 444 penetrates the pinion shaft 44 in the diametrical direction. The pinion shaft 44 is provided with a through hole 444 and an insertion hole 782 on the second case portion 7 side aligned in phase around the axis X1. A positioning pin P inserted into the insertion hole 782 passes through the through hole 444 of the pinion shaft 44. As a result, the pinion shaft 44 is supported on the second case portion 7 side with its rotation around axis X1 restricted.

[0050] As shown in Figure 4, at one end 44a of the pinion shaft 44 in the longitudinal direction, the region protruding from the stepped pinion gear 43 is the first shaft portion 445. The first shaft portion 445 is supported by a support hole 61a provided in the first case portion 6 of the differential case 50. At the other end 44b in the longitudinal direction of the pinion shaft 44, the region protruding from the stepped pinion gear 43 is the second shaft portion 446. The second shaft portion 446 is supported by a support hole 71a provided in the second case portion 7 of the differential case 50.

[0051] Here, the first shaft portion 445 refers to the region on one end 44a of the pinion shaft 44 where the stepped pinion gear 43 is not extrapolated. The second shaft portion 446 refers to the region on the other end 44b of the pinion shaft 44 where the stepped pinion gear 43 is not extrapolated. In the pinion shaft 44, the second shaft portion 446 is longer in the direction of axis X1 than the first shaft portion 445.

[0052] The main components of the differential mechanism 5 are described below. Figure 5 is a perspective view of the differential case 50 of the differential mechanism 5. Figure 6 is an exploded perspective view of the differential case 50 of the differential mechanism 5. As shown in Figures 4 to 6, the differential case 50, acting as a case, houses the differential mechanism 5. The differential case 50 is formed by assembling a first case section 6 and a second case section 7 in the direction of the rotation axis X. In this embodiment, the first case section 6 and the second case section 7 of the differential case 50 function as carriers that support the pinion shaft 44 of the planetary reduction gear 4.

[0053] As shown in Figure 6, three pinion mate gears 52 and three pinion mate shafts 51 are provided between the first case section 6 and the second case section 7 of the differential case 50. The pinion mate shafts 51 function as support shafts that support the pinion mate gears 52. The pinion mate shafts 51 are provided at equal intervals in the circumferential direction around the rotation axis X (see Figure 6). Each inner diameter end of the pinion mate shaft 51 is connected to a common connecting portion 510.

[0054] Each pinion mate gear 52 is externally mounted on each pinion mate shaft 51. Each pinion mate gear 52 is in contact with the connecting portion 510 from the radially outer side of the rotation axis X. In this state, each of the pinion mate gears 52 is rotatably supported by the pinion mate shaft 51.

[0055] As shown in Figure 4, a spherical washer 53 is fitted onto the pinion mate shaft 51. The spherical washer 53 is in contact with the spherical outer circumference of the pinion mate gear 52.

[0056] In the differential case 50, side gear 54A is located on one side of the connecting portion 510 in the direction of the rotation axis X, and side gear 54B is located on the other side. Side gear 54A is rotatably supported in the first case portion 6. Side gear 54B is rotatably supported in the second case portion 7. Side gear 54A meshes with the three pinion mate gears 52 from one side in the direction of the rotation axis X. Side gear 54B meshes with the three pinion mate gears 52 from the other side in the direction of the rotation axis X.

[0057] Figures 7 to 10 illustrate the first case section 6. Figure 7 is a perspective view of the first case section 6 as seen from the second case section 7 side. Figure 8 is a plan view of the first case section 6 as seen from the second case section 7 side. Figure 9 is a schematic diagram of the AA cross-section in Figure 8. Figure 9 shows the arrangement of the pinion mate shaft 51 and the pinion mate gear 52 with dashed lines. Figure 10 is a schematic diagram of the AA section in Figure 8. Figure 10 omits the illustration of the connecting beam 62 at the back of the page, and shows the arrangement of the side gear 54A, the stepped pinion gear 43, and the drive shaft 9A with dashed lines.

[0058] As shown in Figures 7 and 8, the first case portion 6 has a ring-shaped base portion 61. The base portion 61 is a plate-like member having a thickness W61 in the direction of the rotation axis X. As shown in Figures 9 and 10, an opening 60 is provided in the center of the base portion 61. On the side of the base portion 61 opposite to the second case portion 7 (right side in the figures), a cylindrical wall portion 611 is provided that surrounds the opening 60. The outer circumference of the cylindrical wall portion 611 is supported by a plate member 8 via a bearing B3 (see Figure 2).

[0059] On the base portion 61, the side facing the second case portion 7 (left side in the figure) is provided with three connecting beams 62 that extend toward the second case portion 7. The connecting beams 62 are provided at equal intervals in the circumferential direction around the rotation axis X (see Figures 7 and 8). The connecting beam 62 has a base portion 63 perpendicular to the base portion 61 and a connecting portion 64 that is wider than the base portion 63.

[0060] As shown in Figure 9, the tip surface 64a of the connecting portion 64 is a flat surface perpendicular to the rotation axis X. The tip surface 64a is provided with a support groove 65 for supporting the pinion mate shaft 51.

[0061] As shown in Figure 8, the support groove 65 is formed in a straight line along the radius line L of the ring-shaped base 61 when viewed from the direction of the rotation axis X. The support groove 65 traverses the central part of the connecting portion 64 in the circumferential direction around the rotation axis X, from the inner diameter side to the outer diameter side. As shown in Figures 9 and 10, the support groove 65 is semicircular in shape, following the outer diameter of the pinion mate shaft 51. The support groove 65 is formed to a depth that can accommodate half of the cylindrical pinion mate shaft 51. That is, the support groove 65 is formed to a depth corresponding to half the diameter Da of the pinion mate shaft 51 (=Da / 2).

[0062] On the inner diameter side (rotation axis X side) of the connecting portion 64, an arc portion 641 is formed in a shape that follows the outer circumference of the pinion mate gear 52. In the arc portion 641, the outer circumference of the pinion mate gear 52 is supported via a spherical washer 53. In the arc portion 641, an oil groove 642 is provided in a direction along the radius line L described above. The oil groove 642 is provided in the range from the support groove 65 of the pinion mate shaft 51 to the gear support portion 66 fixed to the inner circumference of the connecting portion 64.

[0063] The gear support portion 66 is connected to the boundary between the base portion 63 and the connecting portion 64. The gear support portion 66 is oriented perpendicular to the rotation axis X. The gear support portion 66 has a through hole 660 in its center. As shown in Figure 8, the outer circumference of the gear support portion 66 is connected to the inner circumference of the three connecting portions 64. In this state, the center of the through hole 660 is located on the rotation axis X.

[0064] As shown in Figures 9 and 10, the gear support portion 66 is provided with a recess 661 surrounding the through hole 660 on the side opposite to the base portion 61 (left side in the figures). A ring-shaped washer 55 that supports the back surface of the side gear 54A is housed in the recess 661. A cylindrical wall portion 541 is provided on the back surface of the side gear 54A. The washer 55 is fitted onto the cylindrical wall portion 541.

[0065] Viewed from the direction of the rotation axis X, three oil grooves 662 are provided on the surface of the gear support portion 66 on the side of the recess 661. The oil grooves 662 are provided at predetermined intervals in the circumferential direction around the rotation axis X. The oil groove 662 extends from the inner circumference to the outer circumference of the gear support portion 66 along the radius line L described above. The oil groove 662 is connected to the oil groove 642 on the arc portion 641 side described above.

[0066] As shown in Figures 7 and 8, the base portion 61 has a support hole 61a for the pinion shaft 44. The support hole 61a is located in the region between the connecting beams 62, 62 which are spaced apart in the circumferential direction around the rotation axis X. The base portion 61 is provided with a boss portion 616 surrounding the support hole 61a. A washer Wc (see Figure 10), which is externally fitted onto the pinion shaft 44, contacts the boss portion 616 from the direction of the rotation axis X.

[0067] In the base portion 61, an oil groove 617 is provided in the range from the central opening 60 to the boss portion 616. As shown in Figure 8, the oil groove 617 is formed in a tapered shape, with its circumferential width around the rotation axis X narrowing as it approaches the boss portion 616. The oil groove 617 is connected to an oil groove 618 provided in the boss portion 616.

[0068] In the connecting portion 64, bolt holes 67, 67 are provided on both sides of the support groove 65. The connecting portion 64 of the first case portion 6 is joined to the connecting portion 74 on the second case portion 7 side from the direction of the rotation axis X. The first case portion 6 and the second case portion 7 are joined to each other by bolts B that pass through the connecting portion 74 on the second case portion 7 side and are screwed into bolt holes 67, 67.

[0069] Figures 11 to 16 illustrate the second case section 7. Figure 11 is a perspective view of the second case section 7 as seen from the first case section 6 side. Figure 12 is a plan view of the second case section 7 as seen from the first case section 6 side. Figure 13 is a schematic diagram of the AA cross-section in Figure 12. Figure 13 shows the arrangement of the pinion mate shaft 51 and the pinion mate gear 52 with dashed lines. Figure 14 is a schematic diagram of the AA section in Figure 12. Figure 14 omits the illustration of the connecting section 74 at the far end of the page, and shows the arrangement of the side gear 54B, the stepped pinion gear 43, and the drive shaft 9B with dashed lines. Figure 15 is a perspective view of the second case section 7, seen from the opposite side from the first case section 6. Figure 16 is a plan view of the second case section 7 as seen from the opposite side from the first case section 6.

[0070] As shown in Figures 13 and 14, the second case portion 7 has a ring-shaped base portion 71. The base portion 71 is a plate-shaped member having a thickness W71 in the direction of the rotation axis X. A through hole 70 is provided in the central part of the base 71, which penetrates the base 71 in the thickness direction. On the side of the base portion 71 opposite to the first case portion 6 (left side in the figure), there is a cylindrical wall portion 72 surrounding the through hole 70 and a peripheral wall portion 73 surrounding the cylindrical wall portion 72 at predetermined intervals. The tip of the peripheral wall portion 73 is provided with a projection 73a that protrudes toward the rotation axis X. The projection 73a is provided around the entire circumference in the circumferential direction around the rotation axis X.

[0071] As shown in Figure 16, three support holes 71a for the pinion shaft 44 are opened on the outer diameter side of the peripheral wall portion 73. The support holes 71a are provided at predetermined intervals in the circumferential direction around the rotation axis X. Three slits 710 are provided on the inner diameter side of the peripheral wall portion 73, penetrating the base portion 71 in the thickness direction. When viewed from the direction of the rotation axis X, the slit 710 has an arc shape that follows the inner circumference of the peripheral wall portion 73. The slit 710 is formed in the circumferential direction around the rotation axis X within a predetermined angular range.

[0072] In the second case section 7, the slits 710 are provided at predetermined intervals in the circumferential direction around the rotation axis X. Each of the slits 710 is provided across the inner diameter side of the support hole 71a in the circumferential direction around the rotation axis X.

[0073] Between adjacent slits 710, 710 in the circumferential direction around the axis of rotation, three protruding walls 711 are provided, projecting toward the front of the paper. The protruding walls 711 extend linearly in the radial direction of the axis of rotation X. The protruding walls 711 are provided spanning the outer diameter circumferential wall portion 73 and the inner diameter cylindrical wall portion 72.

[0074] The protruding walls 711 are provided at predetermined intervals in the circumferential direction around the rotation axis X. The protruding walls 711 are provided with a phase difference of approximately 45 degrees relative to the slit 710 in the circumferential direction around the rotation axis X.

[0075] On the outer diameter side of the peripheral wall portion 73, bolt housing portions 76, 76 are provided between adjacent support holes 71a, 71a in the circumferential direction around the rotation axis X, recessed toward the back of the paper. These bolt housing portions 76, 76 are provided in a symmetrical positional relationship with respect to the radius line L. The bolt housing portions 76 open to the outer circumference 71c of the base portion 71. A bolt insertion hole 77 is provided inside the bolt housing portion 76. The insertion hole 77 penetrates the base portion 71 in the thickness direction (direction of the rotation axis X).

[0076] As shown in Figures 11 and 12, the base portion 71 is provided with three connecting portions 74 that protrude toward the first case portion 6 on the surface facing the first case portion 6 (right side in the figures). The connecting portions 74 are provided at equal intervals in the circumferential direction around the rotation axis X. The connecting portions 74 are formed with the same circumferential width W7 as the connecting portion 64 on the first case portion 6 side.

[0077] As shown in Figure 13, the tip surface 74a of the connecting portion 74 is a flat surface perpendicular to the rotation axis X. The tip surface 74a is provided with a support groove 75 for supporting the pinion mate shaft 51.

[0078] As shown in Figure 12, the support groove 75 is formed in a straight line along the radius line L of the base 71 when viewed from the direction of the rotation axis X. The support groove 75 is formed to cross the connecting portion 74 from the inner diameter side to the outer diameter side. As shown in Figure 5, the support groove 75 is semicircular in shape and follows the outer diameter of the pinion mate shaft 51. As shown in Figure 13, the support groove 75 is formed to a depth that can accommodate half of the cylindrical pinion mate shaft 51. That is, the support groove 75 is formed to a depth corresponding to half the diameter Da of the pinion mate shaft 51 (=Da / 2).

[0079] An arc portion 741 is provided on the inner diameter side (rotation axis X side) of the connecting portion 74, which follows the outer circumference of the pinion mate gear 52. In the arc portion 741, the outer circumference of the pinion mate gear 52 is supported via a spherical washer 53 (see Figures 13 and 14). In the arc portion 741, an oil groove 742 is provided in a direction along the radius line L described above. The oil groove 742 is provided in the range from the support groove 75 of the pinion mate shaft 51 to the base portion 71 located on the inner circumference of the connecting portion 74.

[0080] The oil groove 742 is connected to an oil groove 712 provided on the surface 71b of the base 71. Viewed from the direction of the rotation axis X, the oil groove 712 is provided along the radius line L and extends to the through hole 70 provided in the base 71. A ring-shaped washer 55 is placed on the surface 71b of the base 71 to support the back surface of the side gear 54B. A cylindrical wall portion 540 is provided on the back surface of the side gear 54B. The washer 55 is fitted onto the cylindrical wall portion 540.

[0081] An oil groove 721 is formed on the inner circumference of the cylindrical wall portion 72 surrounding the through hole 70, at a position that intersects with the oil groove 712. On the inner circumference of the cylindrical wall portion 72, the oil groove 721 is provided along the entire length of the cylindrical wall portion 72 in the direction of the rotation axis X.

[0082] As shown in Figures 11 and 12, at the base 71 of the second case section 7, a guide section 78 is provided between adjacent connecting sections 74, 74 in the circumferential direction around the rotation axis X. The guide section 78 protrudes toward the first case section 6 side (towards the front of the page). Viewed from the direction of the rotation axis X, the guide portion 78 is cylindrical. The guide portion 78 surrounds the support hole 71a provided in the base portion 71. The outer circumference of the guide portion 78 is cut along the outer circumference 71c of the base portion 71.

[0083] As shown in Figures 13 and 14, in a cross-sectional view along axis X1, the pinion shaft 44 is inserted into the support hole 71a of the guide portion 78 from the first case portion 6 side. The pinion shaft 44 is positioned by the positioning pin P, with its rotation around axis X1 restricted. In this state, the small-diameter gear portion 432 of the stepped pinion gear 43, which is externally fitted onto the pinion shaft 44, is in contact with the guide portion 78 from the direction of the axis X1, with a washer Wc in between.

[0084] As shown in Figure 4, in the differential case 50, a bearing B2 is externally fitted onto the cylindrical wall portion 72 of the second case portion 7. The bearing B2 externally fitted onto the cylindrical wall portion 72 is held by the support portion 145 of the fourth box 14. The cylindrical wall portion 72 of the differential case 50 is rotatably supported by the fourth box 14 via the bearing B2.

[0085] A drive shaft 9B, which has passed through the opening 145a of the fourth box 14, is inserted into the support portion 145 from the direction of the rotation axis X. The drive shaft 9B is rotatably supported by the support portion 145. A lip seal RS is fixed to the inner circumference of the opening 145a. The lip portion of the lip seal RS (not shown) elastically contacts the outer circumference of the cylindrical wall portion 540 of the side gear 54B, which is externally fitted onto the drive shaft 9B. This seals the gap between the outer circumference of the cylindrical wall portion 540 of the side gear 54B and the inner circumference of the opening 145a.

[0086] The first case portion 6 of the differential case 50 is supported by a plate member 8 via a bearing B3 fitted onto the cylindrical wall portion 611 (see Figure 2).

[0087] Inside the first case section 6, a drive shaft 9A is inserted from the direction of the rotation axis, passing through the insertion hole 130a of the third box 13. The drive shaft 9A is positioned across the inner diameter side of the motor shaft 20 of the motor 2 and the sun gear 41 of the planetary reduction gear 4 in the direction of the rotation axis X.

[0088] As shown in Figure 4, inside the differential case 50, side gears 54A and 54B are spline-fitted to the outer circumference of the tip of the drive shaft 9 (9A and 9B). The side gears 54A and 54B and the drive shaft 9 (9A and 9B) are connected so that they can rotate as a single unit around the rotation axis X.

[0089] In this configuration, the side gears 54A and 54B are positioned opposite each other with a gap in the direction of the rotation axis X. The connecting portion 510 of the pinion mate shaft 51 is located between the side gears 54A and 54B. In this embodiment, a total of three pinion mate shafts 51 extend radially outward from the connecting portion 510. A pinion mate gear 52 is supported on each of the pinion mate shafts 51. The pinion mate gear 52 is assembled with side gears 54A located on one side and side gears 54B located on the other side in the rotation axis X direction, with their teeth meshing with each other.

[0090] As shown in Figure 2, lubricating oil OL is stored inside the fourth box 14. The lower side of the differential case 50 is located within the stored oil OL. In this embodiment, when the connecting beam 62 is in its lowest position, the oil OL is stored up to the height at which the connecting beam 62 is located within the oil OL. The stored oil OL is scraped up by the differential case 50, which rotates around the rotation axis X, when the output rotation of the motor 2 is transmitted.

[0091] Figures 17 to 25 illustrate the oil catch section 15. Figure 17 is a plan view of the fourth box 14 as seen from the third box 13 side. Figure 18 is a perspective view of the oil catch section 15 shown in Figure 17, viewed from diagonally above. Figure 19 is a plan view of the fourth box 14 as seen from the third box 13 side. Figure 19 shows the differential case 50 in place. Figure 20 is a perspective view of the oil catch section 15 shown in Figure 19, viewed from diagonally above. Figure 21 is a cross-sectional view of AA in Figure 19. Figure 22 is a schematic diagram illustrating the positional relationship between the oil catch section 15 and the differential case 50 (first case section 6, second case section 7) when the power transmission device 1 is viewed from above. Figure 23 is a view of the catch section 153 from above. Figure 24 is a cross-sectional view AA of Figure 23, illustrating the inclination of the inclined section 156. Figure 25 is a cross-sectional view of BB in Figure 23, illustrating the inclination of the inclined section 157. In Figures 24 and 25, the inclinations of inclined sections 156 and 157 are exaggerated, and parts other than the inclined sections are omitted as appropriate. In addition, in Figures 17 and 19, hatching is used to clearly show the positions of the joint 142 of the fourth box 14 and the support wall 146.

[0092] As shown in Figure 17, the fourth box 14, viewed from the direction of the rotation axis X, is provided with support wall portions 146 that surround the central opening 145a at predetermined intervals. The inside of the support wall portions 146 (rotation axis X) is the housing portion 140 of the differential case 50 (see Figure 19). Within the fourth box 14, above the horizontal line HL passing through the rotation axis X, the space for the oil catch section 15 and the space for the breather chamber 16 are formed. Here, the horizontal line HL is the horizontal line HL based on the installation state of the power transmission device 1 in the vehicle. When viewed from the direction of the rotation axis X, the horizontal line HL is perpendicular to the rotation axis X.

[0093] In the support wall portion 146 of the fourth box 14, a communication opening 147 is provided in the region intersecting with the vertical line VL, connecting the oil catch portion 15 and the housing portion 140 of the differential case 50. The communication opening 147 is formed as a notch in the support wall portion 146, which serves as the ring gear support portion.

[0094] As shown in Figure 17, the oil catch section 15 and the breather chamber 16 are located on one side (left side in the figure) and the other side (right side in the figure) of a vertical line VL perpendicular to the rotation axis X. The oil catch section 15 is positioned offset from the vertical line VL that passes through the rotation center (rotation axis X) of the differential case 50. As shown in Figure 22, when viewed from above, the oil catch section 15 is positioned offset from directly above the differential case 50. Here, the vertical line VL is the vertical line VL based on the installation state of the power transmission device 1 on the vehicle. When viewed from the direction of the rotation axis X, the vertical line VL is perpendicular to the rotation axis X and the horizontal line HL.

[0095] As shown in Figure 18, the oil catch section 15 extends beyond the support wall section 146 towards the back of the paper. A support base section 151, which serves as a shelf, is provided at the lower edge of the oil catch section 15, projecting toward the front of the paper. The support base section 151 is located in front of the support wall section 146 and extends beyond the joint section 142 of the fourth box 14 towards the back of the paper.

[0096] As shown in Figure 17, when viewed from the direction of the rotation axis X, a communication opening 147 is formed on the vertical VL side (right side in the figure) of the oil catch section 15 by cutting out a part of the support wall section 146. The communication opening 147 connects the oil catch section 15 to the housing section 140 of the differential case 50. With the formation of the communication opening 147, the support wall section 146 takes on a C-shape when viewed from the direction of the rotation axis X. When viewed from the direction of the rotation axis X, the communication port 147 is provided in a range that crosses the vertical line VL from the breather chamber 16 side (right side in the figure) to the oil catch section 15 side (left side in the figure). The communication port 147 is located adjacent to the support base 151 provided on the oil catch section 15 in the circumferential direction around the rotation axis X. This makes it easier for the oil OL scraped up by the differential case 50 to enter the support base 151 through the communication port 147.

[0097] As shown in Figure 19, in this embodiment, when the vehicle equipped with the power transmission device 1 is traveling forward, the differential case 50 rotates in a counterclockwise direction (CCW) around the rotation axis X when viewed from the third box 13 side. Therefore, the oil catch section 15 is located on the downstream side in the rotational direction of the differential case 50. The circumferential width of the communication opening 147 is wider on the left side of the vertical line VL than on the right side. The left side of the vertical line VL is the downstream side in the rotational direction of the differential case 50, and the right side is the upstream side. As a result, a large portion of the oil OL scraped up by the differential case 50 as it rotates around the rotation axis X can flow into the oil catch section 15.

[0098] Furthermore, as shown in Figure 22, the outer circumference position of the rotational trajectory of the second shaft portion 446 and the outer circumference position of the rotational trajectory of the large-diameter gear portion 431 are offset in the radial direction of the rotation axis X. The outer circumference position of the rotational trajectory of the second shaft portion 446 is located on the inner diameter side than the outer circumference position of the rotational trajectory of the large-diameter gear portion 431. Therefore, there is spatial clearance on the outer diameter side of the second shaft portion 446. By utilizing this space to provide the oil catch portion 15, the space inside the main body box 10 can be effectively utilized.

[0099] Furthermore, the second shaft portion 446 protrudes from the rear side of the small-diameter gear portion 432 when viewed from the motor 2. The surrounding members of the second shaft portion 446 (for example, the guide portion 58 of the differential case 50 that supports the second shaft portion 446) are positioned close to the oil catch portion 15. Therefore, the supply of oil OL (lubricating oil) from the surrounding components to the oil catch section 15 can be made smooth.

[0100] As shown in Figure 18, an oil hole 151a is provided on the rear side of the support base 151, opening upward. The oil hole 151a extends from the outer diameter end that opens on the upper surface of the support base 151 to the inner diameter side within the fourth box 14. The inner diameter end of the oil hole 151a opens into the inner circumference of the support portion 145. As shown in Figure 2, the inner diameter end of the oil hole 151a in the support portion 145 is open between the lip seal RS and the bearing B2.

[0101] As shown in Figure 20, an oil guide 152 is placed on the support base 151. The oil guide 152 is provided on the upper part of the support base 151 (shelf) as an oil OL catching member. The oil guide 152 has a catching portion 153 and a guide portion 154 that extends from the catching portion 153 toward the first box 11 side (the front side of the paper).

[0102] As shown in Figure 22, when viewed from above, the support base portion 151 is located radially outward of the rotation axis X, overlapping with a part of the differential case 50 (first case portion 6, second case portion 7), and is positioned to avoid interference with the stepped pinion gear 43 (large diameter gear portion 431). Viewed from the radial direction of the rotation axis X, the catch portion 153 is positioned to overlap with the second shaft portion 446 of the pinion shaft 44. Furthermore, the guide portion 154 is positioned to overlap with the first shaft portion 445 of the pinion shaft 44 and the large-diameter gear portion 431.

[0103] Therefore, as the differential case 50 rotates around the rotation axis X, the oil OL scraped up by the differential case 50 moves toward the catch section 153 and the guide section 154.

[0104] As shown in Figure 23, the catch portion 153 consists of an inclined portion 156 as a second inclined surface and an inclined portion 157 as a first inclined surface. The inclined portion 156 is located on the rear side of the support base portion 151 (upper side in Figure 22) and is connected to the oil hole 151a. The inclined portion 157 is located on the front side of the support base portion 151 (lower side in Figure 22) and is connected to the guide portion 154. The inclined portion 157 is in communication with the inclined portion 156 at one end 157a.

[0105] The inclined portion 156 extends from one end 156a, which is connected to the oil hole 151a, toward the other end 156b, in a direction perpendicular to the rotation axis X. As shown in Figure 24, the surface of the inclined portion 156 is inclined downward from the other end 156b toward the one end 156a.

[0106] As shown in Figure 23, the inclined portion 157 extends from one end 157a to the other end 157b in a direction along the rotation axis X. One end 157a of the inclined portion 157 communicates with the inclined portion 156, and the other end 157b connects to the guide portion 154. As shown in Figure 25, the surface of the inclined portion 157 is inclined downward from one end 157a to the other end 157b.

[0107] As shown in Figure 20, a wall portion 153a is erected on the outer periphery of the inclined portions 156 and 157 of the catch portion 153. The wall portion 153a extends in the direction away from the support base portion 151 (upward). A portion of the oil OL caught by the catch portion 153 is held and stored in the oil guide 152 by the wall portion 153a. The surfaces of inclined sections 156 and 157 are inclined, respectively. As a result, as shown in Figure 22, some of the oil OL caught in inclined section 156 flows toward the oil hole 151a due to gravity. Some of the oil OL caught in inclined section 157 flows toward the guide section 154 due to gravity.

[0108] As shown in Figure 23, a notch 155 is provided in the wall portion 153a extending from one end 156a of the inclined portion 156. The notch 155 is located in the region opposite the oil hole 151a. A portion of the oil OL that flows toward the oil hole 151a is discharged toward the oil hole 151a from the portion of the notch 155. In other words, the notch 155 acts as an inlet, guiding the oil OL into the oil hole 151a.

[0109] Here, as shown in Figures 24 and 25, the inclination angle α of the inclined portion 156 with respect to the horizontal line HL is smaller than the inclination angle β of the inclined portion 157 with respect to the horizontal line HL. In other words, the inclined portion 156 has a gentler slope than the inclined portion 157. The opening area of ​​the oil hole 151a is smaller than the area of ​​the guide portion 154. Therefore, the amount of oil discharged from the oil hole 151a is smaller than that of the guide portion 154. For this reason, in this embodiment, the inclination of the inclined portion 156 connected to the oil hole 151a is made gentler to suppress the amount of oil OL flowing into the oil hole 151a. By matching the amount of oil OL flowing into the oil hole 151a to the amount of oil OL discharged from the oil hole 151a, the amount of oil OL stored in the catch portion 153 can be appropriately maintained.

[0110] The guide portion 154 slopes downward as it moves away from the catch portion 153. As shown in Figure 20, walls 154a, 154a are provided on both sides of the guide portion 154 in the width direction. The walls 154a, 154a are provided along the entire length of the guide portion 154 in the longitudinal direction. The walls 154a, 154a are connected to the wall portion 153a that surrounds the outer circumference of the catch portion 153. As shown in Figure 23, a portion of the oil OL stored in the inclined portion 157 of the catch portion 153 is discharged towards the guide portion 154. In other words, the guide portion 154 acts as a branching port, branching off a portion of the oil OL stored in the catch portion 153 and guiding it to a location other than the oil hole 151a.

[0111] As shown in Figure 21, the guide portion 154 extends toward the second box 12 in a position that avoids interference with the differential case 50. The tip 154b of the guide portion 154 faces the through hole 126a provided in the wall portion 120 of the second box 12, with a gap in the direction of the rotation axis X. A boss portion 126 surrounding the through hole 126a is provided on the outer circumference of the wall portion 120. One end of the pipe 127 is fitted into the boss portion 126 from the direction of the rotation axis X.

[0112] The pipe 127 extends from the outside of the second box 12 to the third box 13. The other end of the pipe 127 communicates with an oil hole 136a (see Figure 2) provided in the cylindrical connecting wall 136 of the third box 13.

[0113] A portion of the oil OL, which is scooped up by the differential case 50 rotating around the rotation axis X, reaches the oil catch section 15. The oil OL is supplied to the internal space Sc of the connecting wall 136 through the guide section 154 and the piping 127.

[0114] The third box 13 is provided with a radial oil passage 137 that communicates with the internal space Sc. The radial oil passage 137 extends radially downward from the internal space Sc. The radial oil passage 137 communicates with the axial oil passage 138 provided within the joint 132.

[0115] The axial oil passage 138 is connected to the oil reservoir 128 located at the bottom of the second box 12 via a communication hole 112a provided in the joint 112 of the first box 11. The oil reservoir 128 penetrates the circumferential wall 121 in the direction of the rotation axis X. The oil reservoir 128 is connected to the second gear chamber Sb2 provided in the fourth box 14.

[0116] The operation of the power transmission device 1 with this configuration will be explained. As shown in Figure 1, the power transmission device 1 is provided with a planetary reduction gear 4, a differential mechanism 5, and drive shafts 9 (9A, 9B) along the transmission path of the output rotation of the motor 2.

[0117] As shown in Figure 2, when the rotor core 21 rotates around the rotation axis X due to the drive of the motor 2, rotation is input to the sun gear 41 of the planetary reduction gear 4 via the motor shaft 20, which rotates integrally with the rotor core 21.

[0118] As shown in Figure 3, in the planetary reduction gear 4, the sun gear 41 is the input part for the output rotation of the motor 2. The differential case 50 that supports the stepped pinion gear 43 is the output part for the input rotation.

[0119] When the sun gear 41 rotates around the rotation axis X with the input rotation, the stepped pinion gear 43 (large diameter gear section 431, small diameter gear section 432) rotates around the axis X1 with the rotation input from the sun gear 41 side. Here, the small-diameter gear portion 432 of the stepped pinion gear 43 meshes with the ring gear 42 fixed to the inner circumference of the fourth box 14. Therefore, the stepped pinion gear 43 rotates on its own axis X1 while revolving around the axis of rotation X. The axis of rotation X is the center of revolution of the stepped pinion gear 43 (pinion gear).

[0120] Here, the outer diameter R2 of the small-diameter gear portion 432 of the stepped pinion gear 43 is smaller than the outer diameter R1 of the large-diameter gear portion 431 (see Figure 3). As a result, the differential case 50 (first case section 6, second case section 7) supporting the stepped pinion gear 43 rotates around the rotation axis X at a rotational speed lower than the rotation input from the motor 2. Therefore, the rotation input to the sun gear 41 of the planetary reduction gear 4 is significantly reduced by the stepped pinion gear 43. The reduced rotation is output to the differential case 50 (differential mechanism 5).

[0121] Then, as the differential case 50 rotates around the rotation axis X with the input rotation, the drive shafts 9 (9A, 9B) that mesh with the pinion mate gear 52 rotate around the rotation axis X within the differential case 50. As a result, the left and right drive wheels (not shown) of the vehicle on which the power transmission device 1 is installed rotate with the transmitted rotational force.

[0122] As shown in Figure 2, lubricating oil OL is stored inside the fourth box 14. Therefore, when the output rotation of the motor 2 is transmitted, the stored oil OL is scraped up by the differential case 50 which rotates around the rotation axis X. The oil OL that is scraped up lubricates the meshing parts between the sun gear 41 and the large-diameter gear section 431, the meshing parts between the small-diameter gear section 432 and the ring gear 42, and the meshing parts between the pinion mate gear 52 and the side gears 54A and 54B.

[0123] As shown in Figure 19, the differential case 50 rotates in a counterclockwise direction (CCW) around the rotation axis X when viewed from the third box 13 side. An oil catch section 15 is provided at the top of the fourth box 14. The oil catch section 15 is located on the downstream side in the rotational direction of the differential case 50. Most of the oil OL scraped up by the differential case 50 flows into the oil catch section 15.

[0124] As shown in Figure 22, an oil guide 152 is provided inside the oil catch section 15, which is mounted on a support base section 151. The guide portion 154 and catch portion 153 of the oil guide 152 are located radially outward of the first case portion 6 of the differential case 50 and radially outward of the second case portion 7 of the differential case 50. Therefore, much of the oil OL that is scooped up by the differential case 50 and flows into the oil catch section 15 is captured by the oil guide 152. A portion of the oil OL captured by the inclined portion 156 of the oil guide 152 flows along the inclination toward the oil hole 151a. The oil OL is discharged from the notch 155 provided in the wall portion 153a and flows into the oil hole 151a, which has one end open on the upper surface of the support base portion 151.

[0125] The inner diameter end of the oil hole 151a opens into the inner circumference of the support portion 145 (see Figure 2). Therefore, the oil OL that flows into the oil hole 151a is discharged into the gap Rx between the inner circumference of the support portion 145 of the fourth box 14 and the cylindrical wall portion 540 of the side gear 54B.

[0126] A portion of the oil OL discharged into the gap Rx lubricates the bearing B2 supported by the support portion 145. The oil OL that has lubricated the bearing B2 moves towards the outer diameter due to the centrifugal force caused by the rotation of the differential case 50. On the outer diameter side of the differential case 50, a slit 710 is provided along the inner circumference of the peripheral wall portion 73. The peripheral wall portion 73 prevents the oil OL from moving further towards the outer diameter. The oil OL passes through the slit 710 towards the first case portion 6.

[0127] On the first case portion 6 side of the slit 710, the internal case oil passage 781 is open on the inner circumference of the guide portion 78. A portion of the oil OL that has passed through the slit 710 flows into the internal case oil passage 781 due to the centrifugal force caused by the rotation of the differential case 50. The oil OL that flows into the case oil passage 781 flows through the introduction passage 441 into the shaft oil passage 440 of the pinion shaft 44. The oil OL that flows into the shaft oil passage 440 is discharged radially outward from the oil holes 442 and 443. The discharged oil OL lubricates the needle bearing NB that is fitted onto the pinion shaft 44.

[0128] Furthermore, as shown in Figures 13 and 14, some of the oil OL discharged into the gap Rx passes through an oil groove 721 provided on the inner circumference of the cylindrical wall portion 72 of the second case portion 7. The oil OL that passes through the oil groove 721 is supplied to the washer 55 that supports the back surface of the side gear 54B, and lubricates the washer 55. Furthermore, the oil OL passes through an oil groove 712 provided in the base portion 71 of the second case portion 7 and an oil groove 742 provided in the arc portion 741. The oil OL that passes through the oil groove 742 is supplied to the spherical washer 53 that supports the back surface of the pinion mate gear 52, and lubricates the spherical washer 53.

[0129] Furthermore, as shown in Figure 22, a portion of the oil OL captured by the inclined portion 157 of the oil guide 152 of the oil catch section 15 flows along the inclination toward the guide section 154. The oil OL then flows along the inclination of the guide section 154. As shown in Figure 21, the tip 154b of the guide section 154 faces the through hole 126a provided in the wall portion 120 of the second box 12, with a gap in the direction of the rotation axis X. Therefore, most of the oil OL that flows into the guide section 154 flows into the through hole 126a of the second box 12.

[0130] A boss portion 126 surrounding the through hole 126a is provided on the outer circumference of the wall portion 120. One end of the pipe 127 is fitted into the boss portion 126 from the direction of the rotation axis X. The pipe 127 extends from the outside of the second box 12 to the third box 13. The other end of the pipe 127 communicates with an oil hole 136a (see Figure 2) provided in the cylindrical connecting wall 136 of the third box 13.

[0131] Therefore, in this embodiment, a portion of the oil OL that reaches the oil catch section 15 is supplied to the internal space Sc of the connecting wall 136 through the guide section 154 and the piping 127. The oil OL discharged from the oil hole 136a into the internal space Sc is stored in the internal space Sc. The oil OL also lubricates the bearing B4 supported by the peripheral wall portion 131 of the third box 13.

[0132] A portion of the oil OL discharged into the internal space Sc travels through the gap between the outer circumference of the drive shaft 9A and the inner circumference of the motor shaft 20 to the other end 20b of the motor shaft 20. As shown in Figure 10, the other end 20b of the motor shaft 20 is inserted inside the cylindrical wall portion 541 of the side gear 54A. A communication passage 542 is provided on the inner circumference of the cylindrical wall portion 541, which communicates with the back surface of the side gear 54A. Therefore, some of the oil OL that moves to the other end 20b of the motor shaft 20 and is discharged inside the cylindrical wall portion 541 passes through the connecting passage 542. The oil OL that passes through the connecting passage 542 is supplied to the washer 55 on the back of the side gear 54A, lubricating the washer 55.

[0133] Furthermore, the oil OL that lubricates the washer 55 on the back of the side gear 54A passes through the oil groove 662 provided in the gear support portion 66 of the first case portion 6 and the oil groove 642 provided in the arc portion 641. The oil OL that has passed through the oil groove 642 is supplied to the spherical washer 53 that supports the back of the pinion mate gear 52, and lubricates the spherical washer 53.

[0134] Furthermore, as shown in Figure 2, the internal space Sc of the third box 13 is connected to the second gear chamber Sb2 provided in the fourth box 14 via the radial oil passage 137, the axial oil passage 138, the communication hole 112a, and the oil reservoir 128 provided at the bottom of the second box 12. Therefore, the oil OL in the internal space Sc is maintained at the same height as the oil OL stored in the fourth box 14.

[0135] In this way, much of the oil OL scraped up by the differential case 50 rotating around the rotation axis X flows into the oil catch section 15. The oil OL is supplied from the oil catch section 15 into the support section 145 of the fourth box 14 to lubricate the bearing B2. The oil OL is also supplied from the oil catch section 15 into the internal space Sc of the third box 13 to lubricate the bearing B4. The oil OL that lubricated these bearings B2 and B4 is then returned to the fourth box 14 and scraped up by the rotating differential case 50.

[0136] Therefore, in the power transmission device 1, when the drive wheels W rotate, the oil OL in the fourth box 14 is scooped up and used to lubricate the bearings and the meshing parts of the gears. The oil OL used for lubrication is returned to the fourth box 14 and scooped up again.

[0137] As described above, the power transmission device 1 according to this embodiment has the following configuration. (1) The power transmission device 1 has a differential mechanism 5, a differential case 50 (case) housing the differential mechanism 5, and a stepped pinion gear 43 (pinion gear) supported by the differential case 50, all within a fourth box 14 (box). The fourth box 14 has a support base portion 151 (shelf portion) above the horizontal line HL passing through the rotation axis X, which is the orbital center of the stepped pinion gear 43.

[0138] The oil OL, which is scooped up by the rotation of the stepped pinion gear 43, is caught on the upper side of the support base 151, that is, on the surface of the support base 151, or on the oil guide 152 placed on the support base 151. This makes it possible to supply oil OL to various locations from the upper side of the support base 151. In other words, by providing the support base 151, the degree of freedom in designing the supply of oil OL scooped up by the rotation of the stepped pinion gear 43 can be increased.

[0139] (2) The support base portion 151 has an oil hole 151a that opens upward.

[0140] The oil OL, which is scooped up by the rotation of the stepped pinion gear 43 and falls to the upper side of the support base 151, is introduced into the upward-opening oil hole 151a. This configuration allows the oil OL to be guided into the oil hole 151a more efficiently than a configuration in which the scooped-up oil OL is introduced through a sideways-opening oil hole 151a.

[0141] (3) The power transmission device 1 has an oil guide 152 (catch member) provided on the upper part of the support base 151. The oil guide 152 is provided with a notch 155 (inlet) that guides oil OL into the oil hole 151a.

[0142] When oil OL is caught by the oil guide 152 provided on the upper part of the support base 151, gravity is used to introduce the oil OL from the notch 155 into the oil hole 151a provided in the support base 151. This configuration allows for efficient use of the oil OL. In this embodiment, the notch 155 is provided as an inlet, but the shape of the inlet is not limited. For example, the inlet may be an oil hole provided on the bottom or side of the oil guide 152.

[0143] (4) The oil guide 152 is provided with a guide section 154 (branching port) that guides oil OL to locations other than the oil hole 151a.

[0144] The amount of oil OL that can pass through the oil holes 151a formed in the oil guide 152 is small compared to the capacity of oil OL that the oil guide 152 can catch. Therefore, the excess oil OL caught by the oil guide 152 is branched off by the guide section 154 and used for lubrication in another area. This configuration enables the efficient use of oil OL.

[0145] (5) The oil guide 152 has an inclined portion 157 (first inclined surface) that connects to the guide portion 154 and an inclined portion 156 (second inclined surface) that connects to the notch portion 155. The inclination angle α of the inclined portion 156 is smaller than the inclination angle β of the inclined portion 157.

[0146] Because the oil OL flows according to gravity through the two inclined sections 156 and 157, the oil OL can be smoothly guided to the notch 155 and guide section 154 to which each of the inclined sections 156 and 157 connects. Furthermore, the inclination angle α of the inclined section 156 connected to the notch 155 is made gentler than the inclination angle β of the inclined section 157. As a result, the oil OL does not immediately flow to the notch 155 in the inclined section 156, but is held in the inclined section 156 for a certain period of time. This configuration enhances the oil OL retention function of the catch section 153 of the oil guide 152.

[0147] (6) The power transmission device 1 has a ring gear 42 that meshes with a stepped pinion gear 43. The fourth box 14 has a support wall portion 146 (ring gear support portion) that meshes with the ring gear 42. The support wall portion 146 has a communication opening 147 (notch) at a position adjacent to the support base portion 151 in the circumferential direction.

[0148] By providing a communication opening 147 in the support wall portion 146 that meshes with the ring gear 42, the supply of oil OL to the support base portion 151 can be made smoother. Specifically, some of the oil OL scattered by the rotation of the stepped pinion gear 43 is scattered in a direction toward the support base portion 151, overflowing the outer circumference of the ring gear 42. The support wall portion 146 that meshes with the ring gear 42 can obstruct this flow of oil OL toward the support base portion 151. Therefore, a communication opening 147 is provided in the support wall portion 146 to guide the oil OL toward the support base portion 151. In other words, forming a notch as the communication opening 147 means that the support wall portions 146 that mesh with the ring gear 42 are arranged on both sides of the notch. That is to say, the structure of this embodiment is a structure that increases the stability of the support of the ring gear 42.

[0149] (7) The support wall portion 146 has a C-shape.

[0150] The support wall portion 146 may be composed of, for example, a plurality of individual support portions arranged on the outer circumference of the ring gear 42. However, as in the embodiment, by forming the support wall portion 146 in a C-shape when viewed from the direction of the rotation axis X, and surrounding the outer circumference of the ring gear 42, the area of ​​the portion supporting the ring gear 42 can be increased. This configuration can increase the support stability of the ring gear 42.

[0151] The power transmission device 1 according to this embodiment has the following configuration. (8) The power transmission device 1 includes a motor 2 positioned upstream of the transmission path of rotational driving force of the sun gear 41 which meshes with the stepped pinion gear 43, and a drive shaft 9A (drive shaft) connected to the differential mechanism 5. The drive shaft 9A passes through the inner circumference of the sun gear 41 and the motor 2.

[0152] The power transmission device 1 is a power transmission device for a single-axle electric vehicle and can provide a compact power transmission device.

[0153] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments shown. It can be modified as appropriate within the scope of the technical idea of ​​the invention. [Explanation of symbols]

[0154] 1. Power transmission device 2 motors 3. Park Lock Mechanism 4 Planetary reduction gears 5 Differential mechanism 6. Case 1 7. Case Section 2 8 Plate members 9 Drive shaft 9A Drive shaft 9B drive shaft 10 Main box 11 Box 1 12 Box 2 13 Box 3 14. Box 4 (Box) 15 Oil catch section 16. Breather Room 20 Motor shaft 41 Sangear 42 Ring Gear 43-stage pinion gear (pinion gear) 44 Pinion shaft 50 Differential Case (Case) 146 Support wall section (ring gear support section) 147 Communication opening (notch) 151 Support part (shelf part) 151a Oil hole 152 Oil guide (catch component) 154 Guide section (branching point) 155 Notch (Inlet) 156 Inclined section (second inclined surface) 157 Slope part (first slope) X axis of rotation (center of rotation of the pinion gear) HL horizontal line α, β Tilt angle

Claims

1. Motor and, Differential mechanism, A case housing the differential mechanism, The aforementioned case supports a planetary gear mechanism, which is housed within a box. The planetary gear mechanism includes a sun gear connected downstream of the motor shaft of the motor, and a pinion gear including a large-diameter gear portion that meshes with the sun gear and a small-diameter gear portion provided axially aligned with the large-diameter gear portion. The box is positioned above the horizontal line passing through the center of rotation of the pinion gear, and when viewed radially, has a portion that overlaps with the large-diameter gear portion and the small-diameter gear portion, and includes an oil catch portion for catching oil scraped up by the pinion gear, and an oil inlet positioned to overlap with the sun gear when viewed radially above, for guiding the oil to the oil catch portion. The oil catch portion is positioned so as not to overlap with the sun gear when viewed from radially above. The oil catch portion is positioned so as not to overlap with the sun gear when viewed from the horizontal direction, and is positioned adjacent to the oil inlet on the circumferential downstream side around the orbital axis of the large-diameter gear portion. The box has an oil hole that opens at one end of the motor shaft, The planetary gear mechanism is located on the other end side of the motor shaft, The oil supplied to the oil catch section is supplied to one end of the motor shaft through the oil hole in the power transmission device.

2. In claim 1, A power transmission device in which the oil supplied to one end of the motor shaft through the oil hole moves to the other end of the motor shaft through the gap between the outer circumference of the drive shaft connected downstream of the differential mechanism and the inner circumference of the motor shaft.

3. In claim 1 or claim 2, The box has an oil reservoir portion that penetrates axially at the lower part of the motor, A power transmission device in which the oil supplied to one end of the motor shaft through the oil hole moves to the other end of the motor shaft through the oil reservoir.

4. In any one of claims 1 to 3, The oil supplied to the oil catch section is supplied to the oil hole via piping in a power transmission device.

5. In any one of claims 1 to 4, The planetary gear mechanism has a carrier that supports the pinion gear, A power transmission device in which, when viewed from the axial direction, the upper surface of the oil catch portion has a portion that is located higher than the carrier.

Images