Power transmission device

Abstract

To improve the cooling efficiency of oil. A power transmission device (1) has a motor (2), a gear mechanism (4, 5) connected downstream of the motor (2), a case (14) that houses the gear mechanism, a first chamber (Sb) formed in the case (14) that houses the gear mechanism (4, 5) and oil (OL), and a second chamber (CR) formed in the case (14) adjacent to the first chamber (Sb) and into which a coolant liquid (CL) is introduced.

Description

TECHNICAL FIELD

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

[0002] A power transmission device for an electric vehicle having a bevel differential mechanism and a planetary gear mechanism is disclosed in Patent Document 1.

[0003] The planetary gear mechanism has a stepped pinion having a large planetary gear and a small planetary gear.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 8-240254 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In a power transmission device, it is required to improve the cooling efficiency of oil for lubrication supplied to constituent parts.

[0009] TECHNICAL SOLUTION FOR SOLVING THE PROBLEM

[0010] According to one aspect of the present application, there is provided a power transmission device having:

[0011] a motor;

[0012] a gear mechanism connected downstream of the motor;

[0013] a case housing the gear mechanism,

[0014] a first chamber housing the gear mechanism and oil OL is formed in the case,

[0015] a second chamber adjacent to the first chamber into which a coolant is introduced is formed in the case.

[0016] EFFECT OF THE INVENTION

[0017] According to one aspect of the present application, it is possible to improve the cooling efficiency of oil. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic view of a power transmission device.

[0019] Figure 2 is a schematic view of a cross section of a power transmission device.

[0020] Figure 3 is an enlarged view of the surroundings of a planetary reduction gear of a power transmission device.

[0021] Figure 4 is an enlarged view of the differential mechanism of the power transmission device.

[0022] Figure 5 is a perspective view of the differential mechanism of the power transmission device.

[0023] Figure 6 is an exploded perspective view of the differential mechanism of the power transmission device.

[0024] Figure 7 is a view illustrating an oil retaining portion.

[0025] Figure 8 is a view illustrating an oil retaining portion.

[0026] Figure 9 is a view illustrating an oil retaining portion.

[0027] Figure 10 is a view illustrating an oil retaining portion.

[0028] Figure 11 is a view illustrating an oil retaining portion.

[0029] Figure 12 is a view illustrating an oil retaining portion.

[0030] Figure 13 is an enlarged view of the cooling chamber of the lower portion of the fourth case.

[0031] Figure 14 is a view of the cooling chamber as viewed from the peripheral wall portion side of the fourth case.

[0032] Figure 15 is a view showing a state in which the cover portion of the cooling chamber is removed.

[0033] Figure 16 is a view illustrating the flow of the coolant.

[0034] Figure 17 is a view showing the structure of the cover portion.

[0035] Figure 18 is a view illustrating the assembly of the spacer to the cover portion.

[0036] Figure 19 is a view illustrating the flow of the coolant in the cooling chamber. DETAILED DESCRIPTION

[0037] Hereinafter, an embodiment of the present application will be described.

[0038] Figure 1 is a view illustrating the power transmission device 1 of the present embodiment.

[0039] Figure 2 is a view illustrating the power transmission device 1 of the present embodiment.

[0040] Figure 3 is an enlarged view of the surroundings of the planetary reduction gear 4 of the power transmission device 1.

[0041] Figure 4 is an enlarged view of the surroundings of the differential mechanism 5 of the power transmission device 1.

[0042] As shown in Figure 1 , the power transmission device 1 has a motor 2 and a planetary reduction gear 4 (reduction mechanism) that reduces and inputs an output rotation of the motor 2 to a differential mechanism 5. The power transmission device 1 also has drive shafts DA, DB and a park lock mechanism 3.

[0043] In the power transmission device 1, the park lock mechanism 3, the planetary reduction gear 4, the differential mechanism 5, and the drive shafts DA, DB are provided along a transmission path of the output rotation of the motor 2 about the rotation axis X. The axes of the drive shafts DA, DB are coaxial with the rotation axis X of the motor 2.

[0044] In the power transmission device 1, after the output rotation of the motor 2 is reduced by the planetary reduction gear 4 and input to the differential mechanism 5, the output rotation is transmitted to the left and right drive wheels W, W of a vehicle on which the power transmission device 1 is mounted via the drive shafts DA, DB.

[0045] 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. The drive shafts DA, DB are connected downstream of the differential mechanism 5.

[0046] As shown in Figure 2 , the main case 10 of the power transmission device 1 has a first case 11 that houses the motor 2 and a second case 12 that is externally inserted into the first case 11. The main case 10 also has a third case 13 that is assembled to the first case 11 and a fourth case 14 that is assembled to the second case 12.

[0047] The first case 11 has a cylindrical support wall portion 111 and a flange-shaped engagement portion 112 provided to one end 111a of the support wall portion 111.

[0048] The first case 11 is disposed so that the support wall portion 111 is oriented along the rotation axis X of the motor 2. The motor 2 is housed inside the support wall portion 111.

[0049] The engagement portion 112 is disposed so as to be orthogonal to the rotation axis X. The engagement portion 112 is formed so as to have a larger outer diameter than the support wall portion 111.

[0050] The second case 12 has a cylindrical peripheral wall portion 121, a flange-shaped engagement portion 122 provided to one end 121a of the peripheral wall portion 121, and a flange-shaped engagement portion 123 provided to the other end 121b of the peripheral wall portion 121.

[0051] The peripheral wall portion 121 is formed with an inner diameter that can be externally inserted into the support wall portion 111 of the first housing 11 .

[0052] The first housing 11 and the second housing 12 are assembled to each other by inserting the peripheral wall 121 of the second housing 12 onto the support wall 111 of the first housing 11 .

[0053] The joint portion 122 on the side of the one end 121a of the peripheral wall portion 121 contacts the joint portion 112 of the first housing 11 in the direction of the rotation axis X. These joint portions 122 and 112 are connected to each other by bolts (not shown).

[0054] In the first housing 11 , a plurality of grooves 111 b are provided on the outer periphery of the support wall portion 111 . The plurality of grooves 111 b are provided at intervals in the direction of the rotation axis X. Each groove 111 b is provided over the entire circumference around the rotation axis X in the circumferential direction.

[0055] The peripheral wall portion 121 of the second housing 12 is externally inserted into the support wall portion 111 of the first housing 11. The opening of the groove 111b is closed by the peripheral wall portion 121. A plurality of cooling paths CP are formed between the support wall portion 111 and the peripheral wall portion 121, through which the coolant CL flows.

[0056] The inlet 124a of the coolant CL is provided on the side of the joint 122 of the peripheral wall portion 121. The outlet 124b of the coolant CL is provided on the side of the joint 123 of the peripheral wall portion 121. The inlet 124a and the outlet 124b are holes that penetrate the peripheral wall portion 121 in the radial direction of the rotation axis X. A pipe (not shown) through which the coolant CL flows is connected to each of the inlet 124a and the outlet 124b. The coolant CL is circulated in the pipe (not shown) provided inside the vehicle using a water pump (not shown). The coolant CL is introduced from the inlet 124a into the cooling path CP to cool the motor 2. After cooling the motor 2, the coolant CL is discharged from the outlet 124b. The coolant CL is introduced into the cooling chamber CR provided in the fourth housing 14 described later through a pipe (not shown).

[0057] Annular grooves 111c, 111c are formed on the outer periphery of the support wall portion 111 of the first housing 11 on both sides of the region where the groove 111b is provided. Seal rings 113, 113 are fitted externally into the annular grooves 111c, 111c.

[0058] These seal rings 113 are pressed against the inner periphery of the peripheral wall portion 121 inserted outside the support wall portion 111 , thereby sealing the gap between the outer periphery of the support wall portion 111 and the inner periphery of the peripheral wall portion 121 .

[0059] A wall portion 120 extending to the inner diameter side is provided at the other end 121b of the second case 12. The wall portion 120 is provided in a direction orthogonal to the rotation axis X. An opening 120a through which the drive shaft DA is inserted is provided in a region of the wall portion 120 intersecting the rotation axis X.

[0060] In the wall portion 120, a cylindrical motor support portion 125 surrounding the opening 120a is provided on a surface on the motor 2 side (right side in the drawing).

[0061] The motor support portion 125 is inserted inside the coil end 253b described later. The motor support portion 125 opposes the end portion 21b of the rotor core 21 with a gap in the rotation axis X direction.

[0062] In the case of the peripheral wall portion 121 of the second case 12, the radial thickness is thicker in a region on the lower side in the vertical direction with the mounting state of the power transmission device 1 to the vehicle as a reference than in a region on the upper side.

[0063] In the region in which the radial thickness is thick, an oil accumulation portion 128 is provided penetrating in the rotation axis X direction.

[0064] The oil accumulation portion 128 is connected to an axial oil passage 138 provided to the engaging portion 132 of the third case 13 via a communication hole 112a. The communication hole 112a is provided to the engaging portion 112 of the first case 11.

[0065] The third case 13 has a wall portion 130 orthogonal to the rotation axis X. An engaging portion 132 constituting a ring shape as viewed from the rotation axis X direction is provided to the outer peripheral portion of the wall portion 130.

[0066] The third case 13 is located on the side opposite the differential mechanism 5 (right side in the drawing) as viewed from the first case 11. The engaging portion 132 of the third case 13 engages with the engaging portion 112 of the first case 11 from the rotation axis X direction. The third case 13 and the first case 11 are connected to each other by a bolt (not shown). In this state, the opening on the engaging portion 122 side (right side in the drawing) of the support wall portion 111 of the first case 11 is plugged by the third case 13.

[0067] In the third case 13, a through hole 130a of the drive shaft DA is provided to the central portion of the wall portion 130.

[0068] A lip seal RS is provided to the inner periphery of the through hole 130a. The lip seal RS elastically contacts the outer periphery of the drive shaft DA with a lip portion not shown. The gap between the inner periphery of the through hole 130a and the outer periphery of the drive shaft DA is sealed by the lip seal RS.

[0069] A peripheral wall portion 131 that surrounds the insertion hole 130a is provided on the surface of the wall portion 130 on the first case 11 side (left side in the drawing). The drive shaft DA is supported to the inner periphery of the peripheral wall portion 131 via a bearing B4.

[0070] A motor support portion 135 is provided on the motor 2 side (left side in the drawing) as viewed from the peripheral wall portion 131. The motor support portion 135 constitutes a cylinder that surrounds the rotation axis X at an interval.

[0071] A cylindrical connection wall 136 is connected to the outer periphery of the motor support portion 135. The connection wall 136 is formed with a larger outer diameter than the peripheral wall portion 131 on the wall portion 130 side (right side in the drawing). The connection wall 136 is disposed so as to extend in a direction away from the motor 2 along the direction of the rotation axis X. The connection wall 136 connects the motor support portion 135 and the wall portion 130 of the third case 13.

[0072] The motor support portion 135 is supported by the third case 13 via the connection wall 136. The one end 20a side 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.

[0073] A bearing B1 is supported on the inner periphery of the motor support portion 135. The outer periphery of the motor shaft 20 is supported by the motor support portion 135 via the bearing B1.

[0074] A lip seal RS is provided at a position adjacent to the bearing B1.

[0075] In the third case 13, an oil hole 136a described later is provided in the inner periphery of the connection wall 136. The oil OL flows into a space (an inner space Sc) surrounded by the connection wall 136 from the oil hole 136a. The lip seal RS is provided so as to prevent the oil OL inside the connection wall 136 from flowing to the motor 2 side.

[0076] The fourth case 14 has a peripheral wall portion 141 that surrounds the outer periphery of the planetary reduction gear 4 and the differential mechanism 5, and a flange-shaped engagement portion 142 that is provided to the end portion of the peripheral wall portion 141 on the second case 12 side. The fourth case 14 functions as a case that houses the gear mechanism, i.e., the planetary reduction gear 4 and the differential mechanism 5.

[0077] As viewed from the second case 12, the fourth case 14 is located on the differential mechanism 5 side (left side in the drawing).

[0078] The engagement portion 142 of the fourth case 14 engages with the engagement portion 123 of the second case 12 from the direction of the rotation axis X.

[0079] The fourth case 14 and the second case 12 are connected to each other by a bolt (not shown).

[0080] A motor room Sa that accommodates the motor 2 and a gear room Sb (first room) that accommodates the planetary reduction gear 4 and the differential mechanism 5 are formed inside the main body case 10 of the power transmission apparatus 1.

[0081] The motor room Sa is formed between the wall portion 120 of the second case 12 and the wall portion 130 of the third case 13 on the inner side of the first case 11.

[0082] The gear room Sb is formed between the wall portion 120 of the second case 12 and the peripheral wall portion 141 of the fourth case 14 on the inner diameter side of the fourth case 14.

[0083] The plate member 8 is provided inside the gear room Sb.

[0084] The plate member 8 is fixed to the fourth case 14 with bolts B.

[0085] The plate member 8 divides the gear room Sb into a first gear room Sb1 that accommodates the planetary reduction gear 4 and the differential mechanism 5 and a second gear room Sb2 that accommodates the parking lock mechanism 3.

[0086] In the rotational axis X direction, the second gear room Sb2 is located between the first gear room Sb1 and the motor room Sa.

[0087] The motor 2 has a cylindrical motor shaft 20, a cylindrical rotor core 21 that is externally fitted to the motor shaft 20, and a stator core 25 that circumvents the outer periphery of the rotor core 21 at intervals.

[0088] In the motor shaft 20, bearings B1, B1 are externally fitted and fixed on both sides of the rotor core 21. The bearing B1 located on the one end 20a side (right side in the drawing) of the motor shaft 20 is supported to the inner periphery of the motor support portion 135 of the third case 13 as viewed from the rotor core 21. The bearing B1 located on the other end 20b side is supported to the inner periphery of the cylindrical motor support portion 125 of the second case 12.

[0089] The motor support portions 135, 125 are disposed in opposition to the one end portion 21a and the other end portion 21b of the rotor core 21 at intervals in the rotational axis X direction on the inner diameter side of the coil ends 253a, 253b described later.

[0090] The rotor core 21 is formed by laminating a plurality of silicon steel sheets. The silicon steel sheets are each externally fitted to the motor shaft 20 in a state in which relative rotation with the motor shaft 20 is restricted.

[0091] The silicon steel sheets constitute a ring as viewed in the rotational axis X direction of the motor shaft 20. On the outer periphery side of the silicon steel sheets, magnets of N poles and S poles that are not shown are alternately arranged in the peripheral direction around the rotational axis X.

[0092] The stator core 25 surrounding the outer periphery of the rotor core 21 is formed by laminating a plurality of electromagnetic steel sheets. The stator core 25 is fixed to the inner periphery of the cylindrical support wall portion 111 of the first casing 11 .

[0093] Each of the electromagnetic steel sheets includes an annular yoke portion 251 fixed to the inner periphery of the support wall portion 111 and a pole tooth portion 252 protruding from the inner periphery of the yoke portion 251 toward the rotor core 21 .

[0094] In this embodiment, the stator core 25 is configured such that the winding 253 is distributedly wound across a plurality of teeth 252. The stator core 25 is longer in the rotation axis X direction than the rotor core 21 by the coil ends 253a and 253b protruding in the rotation axis X direction.

[0095] Alternatively, a stator core may be employed in which windings are concentratedly wound around each of the plurality of pole teeth 252 protruding toward the rotor core 21 .

[0096] An opening 120 a is provided in the wall portion 120 (motor support portion 125 ) of the second case 12 . The other end 20 b of the motor shaft 20 passes through the opening 120 a on the differential mechanism 5 side (left side in the figure) and is located in the fourth case 14 .

[0097] The other end 20 b of the motor shaft 20 is located inside the fourth housing 14 and faces a side gear 54A, which will be described later, with a gap in the direction of the rotation axis X therebetween.

[0098] like Figure 3 As shown, the motor shaft 20 has a step 201 in the area located inside the fourth housing 14. The step 201 is located near the motor support 125. The lip seal RS supported on the inner periphery of the motor support 125 abuts against the outer periphery of the area between the step 201 and the bearing B1.

[0099] The lip seal RS defines a motor chamber Sa accommodating the motor 2 and a gear chamber Sb in the fourth housing 14 .

[0100] Oil OL for lubricating the planetary reduction gear 4 and the differential mechanism 5 is enclosed in the inner diameter side of the fourth case 14 (see Figure 2 ).

[0101] The lip seal RS is provided to prevent the oil OL from flowing into the motor chamber Sa.

[0102] like Figure 3 As shown, on the motor shaft 20 , the region from the step portion 201 to the vicinity of the other end 20 b forms a fitting portion 202 having a spline provided on the outer periphery.

[0103] The parking gear 30 and the sun gear 41 are spline-fitted to the outer circumference of the fitting portion 202 .

[0104] In the parking gear 30, one side surface thereof is in abutment with the step portion 201 (in the drawing, right side). One end 410a of the cylindrical base portion 410 of the sun gear 41 is in abutment with the other side surface of the parking gear 30 (in the drawing, left side).

[0105] The nut N screwed to the other end 20b of the motor shaft 20 is press-fitted to the other end 410b of the base portion 410 from the direction of the rotation axis X.

[0106] The sun gear 41 and the parking gear 30 are arranged so as not to be relatively rotatable with respect to the motor shaft 20 in a state of being sandwiched between the nut N and the step portion 201.

[0107] The sun gear 41 has a tooth portion 411 on the outer periphery on the other end 20b side of the motor shaft 20. The large-diameter gear portion 431 of the stepped pinion 43 is engaged with the outer periphery of the tooth portion 411.

[0108] The stepped pinion 43 has the large-diameter gear portion 431 engaged with the sun gear 41 and the small-diameter gear portion 432 having a smaller diameter than the large-diameter gear portion 431.

[0109] The stepped pinion 43 is a gear member in which the large-diameter gear portion 431 and the small-diameter gear portion 432 are arranged in the direction of the axis Xl parallel to the rotation axis X and are integrally provided.

[0110] The large-diameter gear portion 431 is formed with an outer diameter Rl larger than an outer diameter R2 of the small-diameter gear portion 432.

[0111] The stepped pinion 43 is arranged with the orientation along the axis Xl. In this state, the large-diameter gear portion 431 is located on the motor 2 side (in the drawing, right side).

[0112] The outer periphery of the small-diameter gear portion 432 is engaged with the inner periphery of the ring gear 42. The ring gear 42 constitutes a ring shape that surrounds the rotation axis X with a gap. A plurality of engagement teeth 421 projecting to the radially outer side are provided on the outer periphery of the ring gear 42. The plurality of engagement teeth 421 are provided with a gap from each other in the circumferential direction around the rotation axis X.

[0113] The ring gear 42 is spline-fitted with the engagement teeth 421 provided on the outer periphery and the tooth portion 146a provided on the support wall portion 146 of the fourth case 14. The rotation of the ring gear 42 around the rotation axis X is restricted.

[0114] The stepped pinion 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 Xl.

[0115] The stepped pinion 43 is supported so as to be rotatable via the needle bearing NB, NB on the outer periphery of the pinion shaft 44 that penetrates the through-hole 430.

[0116] An intermediate spacer MS is interposed between the needle bearing NB that supports the inner periphery of the large-diameter gear portion 431 and the needle bearing NB that supports the inner periphery of the small-diameter gear portion 432 on the outer periphery of the pinion shaft 44.

[0117] As shown in FIG. 6, an inner shaft oil passage 440 is provided inside the pinion shaft 44. The inner shaft oil passage 440 penetrates from one end 44a to the other end 44b of the pinion shaft 44 along the axis X1. Figure 4

[0118] Oil holes 442, 443 that communicate the inner shaft oil passage 440 with the outer periphery of the pinion shaft 44 are provided on the pinion shaft 44.

[0119] The oil hole 443 is provided in a region where the needle bearing NB that supports the inner periphery of the large-diameter gear portion 431 is provided.

[0120] The oil hole 442 is provided in a region where the needle bearing NB that supports the inner periphery of the small-diameter gear portion 432 is provided. On the pinion shaft 44, the oil holes 443, 442 are provided in regions where the stepped pinion gear 43 is fitted.

[0121] In addition, an introduction passage 441 for introducing the oil OL into the inner shaft oil passage 440 is provided on the pinion shaft 44.

[0122] On the outer periphery of the pinion shaft 44, the introduction passage 441 is provided in a region that is located inside the support hole 71a of the second housing portion 7 described later. The introduction passage 441 communicates the inner shaft oil passage 440 with the outer periphery of the pinion shaft 44.

[0123] A housing inner oil passage 781 is provided in the inner periphery of the support hole 71a. The housing inner oil passage 781 communicates the outer periphery of the guide portion 78 that protrudes from the base portion 71 of the second housing portion 7 with the support hole 71a.

[0124] When viewed in cross section along the axis X1, the housing inner oil passage 781 is inclined with respect to the axis X1. The housing inner oil passage 781 is inclined so as to approach the slit 710 provided in the base portion 71 as it goes toward the rotation axis X side.

[0125] The oil OL that is scooped up by the differential case 50 described later flows into the housing inner oil passage 781. The oil OL that moves toward the outer diameter side also flows into the housing inner oil passage 781 by centrifugal force generated by the rotation of the differential case 50.

[0126] The oil OL that flows from the housing inner oil passage 781 into the introduction passage 441 flows into the inner shaft oil passage 440 of the pinion shaft 44. The oil OL that flows into the inner shaft oil passage 440 is discharged to the radially outer side from the oil holes 442, 443. The oil OL that is discharged from the oil holes 442, 443 lubricates the needle bearing NB that is fitted to the pinion shaft 44.

[0127] ​On the pinion shaft 44, a through-hole 444 is provided on the other end 44b side than the region where the lead-in path 441 is provided. The through-hole 444 penetrates the pinion shaft 44 in the diameter line direction.

[0128] The pinion shaft 44 has the through-hole 444 and the insertion hole 782 on the second housing portion 7 side aligned in phase around the axis X1. The positioning pin P inserted into the insertion hole 782 penetrates the through-hole 444 of the pinion shaft 44. Accordingly, the pinion shaft 44 is supported by the second housing portion 7 side in a state where the rotation around the axis X1 is restricted.

[0129] As shown in Figure 4 , on the one end 44a side in the long direction of the pinion shaft 44, the region where the stepped pinion 43 protrudes becomes a first shaft portion 445. The first shaft portion 445 is supported by the support hole 61a of the first housing portion 6 of the differential case 50.

[0130] On the other end 44b side in the long direction of the pinion shaft 44, the region where the stepped pinion 43 protrudes becomes a second shaft portion 446. The second shaft portion 446 is supported by the support hole 71a of the second housing portion 7 of the differential case 50.

[0131] Here, the first shaft portion 445 refers to the region on the one end 44a side of the pinion shaft 44 where the stepped pinion 43 is not externally inserted. The second shaft portion 446 refers to the region on the other end 44b side of the pinion shaft 44 where the stepped pinion 43 is not externally inserted.

[0132] On the pinion shaft 44, the second shaft portion 446 is longer than the first shaft portion 445 in terms of the length in the axis X1 direction.

[0133] Hereinafter, the main structure of the differential mechanism 5 will be described.

[0134] Figure 5 is an exploded perspective view of the differential case 50 and the differential mechanism 5.

[0135] Figure 6 is an exploded perspective view of the differential case 50 and the differential mechanism 5.

[0136] As shown in Figure 4 to Figure 6 , the differential case 50 of the differential mechanism 5 is formed by assembling the first housing portion 6 and the second housing portion 7 in the rotation axis X direction. In the present embodiment, the first housing portion 6 and the second housing portion 7 of the differential case 50 have the function of a planetary gear carrier that supports the pinion shaft 44 of the planetary reduction gear 4.

[0137] As shown in Figure 6As shown, a pinion mating shaft 51 and a pinion mating gear 52 are arranged between the first housing portion 6 and the second housing portion 7 of the differential case 50. Three pinion mating gears 52 and three pinion mating shafts 51 are provided.

[0138] The pinion mating shafts 51 are arranged at equal intervals in the circumferential direction around the rotation axis X.

[0139] The inner diameter side end portions of the respective pinion mating shafts 51 are connected to a common connection portion 510 .

[0140] One pinion mating gear 52 is externally inserted on each pinion mating shaft 51. Each pinion mating gear 52 contacts the connection portion 510 from the radially outer side of the rotation axis X.

[0141] In this state, the pinion mating gears 52 are each rotatably supported by the pinion mating shaft 51 .

[0142] like Figure 4 As shown, a spherical washer 53 is externally inserted on the pinion mating shaft 51. The spherical washer 53 contacts the spherical outer periphery of the pinion mating gear 52.

[0143] In the differential case 50 , the side gear 54A is located on one side of the connection portion 510 in the direction of the rotation axis X, and the side gear 54B is located on the other side. The side gear 54A is rotatably supported by the first case portion 6 , and the side gear 54B is rotatably supported by the second case portion 7 .

[0144] The side gear 54A meshes with the three pinion mating gears 52 from one side in the direction of the rotation axis X. The side gear 54B meshes with the three pinion mating gears 52 from the other side in the direction of the rotation axis X.

[0145] like Figure 6 As shown, the first housing portion 6 has an annular base portion 61. The base portion 61 is a plate-shaped member having a thickness W61 in the direction of the rotation axis X.

[0146] like Figure 4 As shown, an opening 60 is provided in the center of the base 61. A cylindrical wall portion 611 is provided on the surface of the base 61 opposite to the second housing portion 7 (right side in the figure) to surround the opening 60. The outer periphery of the cylindrical wall portion 611 is supported by the plate member 8 via the bearing B3.

[0147] like Figure 6 As shown, three connecting beams 62 extending toward the second case portion 7 are provided on the surface of the base portion 61 on the second case portion 7 side.

[0148] The link beams 62 are provided at equal intervals in the circumferential direction around the rotation axis X. The link beams 62 have bases 63 orthogonal to the base 61 and link portions 64 wider than the bases 63.

[0149] As shown in Figure 4 , a support groove 65 for supporting the pinion gear fitting shaft 51 is provided on the front end surface of the link portion 64.

[0150] On the inner diameter side (rotation axis X side) of the link portion 64, a circular arc portion 641 is formed in a shape following the outer periphery of the pinion gear fitting gear 52.

[0151] The outer periphery of the pinion gear fitting gear 52 is supported to the circular arc portion 641 via a spherical washer 53.

[0152] A gear support portion 66 is connected to the boundary portion of the base 63 and the link portion 64 of the link beam 62. The gear support portion 66 is provided in an orientation orthogonal to the rotation axis X. A through hole 660 is formed in the central portion of the gear support portion 66.

[0153] A recessed portion 661 surrounding the through hole 660 is provided on the surface of the gear support portion 66 on the side opposite to the base 61 (left side in the drawing). A washer 55 in the shape of a ring is housed in the recessed portion 661 so as to cover the back surface of the side gear 54A.

[0154] A cylindrical wall portion 541 is provided on the back surface of the side gear 54A, and the washer 55 is fitted to the wall portion 541.

[0155] As shown in Figure 6 , the link beams 62, 62 of the base 61 are arranged at intervals in the circumferential direction around the rotation axis X. A support hole 61a of the pinion gear shaft 44 is provided in the region between the link beams 62, 62.

[0156] A boss portion 616 surrounding the support hole 61a is provided in the base 61. As shown in Figure 3 , the washer Wc fitted to the pinion gear shaft 44 comes into contact with the boss portion 616 from the direction of the rotation axis X.

[0157] As shown in Figure 6 , an oil groove 617 is provided in the base 61 in the range from the central opening 60 to the boss portion 616. The oil groove 617 is formed in a tapered shape in which the width in the circumferential direction around the rotation axis X narrows as it approaches the boss portion 616. The oil groove 617 is connected to an oil groove 618 provided in the boss portion 616.

[0158] In the link portion 64, bolt holes 67, 67 are provided on both sides of the support groove 65.

[0159] The connecting portion 74 on the second case portion 7 side is joined to the connecting portion 64 on the first case portion 6 in the direction of the rotation axis X. Bolts B (see FIG. 1 ) that penetrate the connecting portion 74 on the second case portion 7 side are screwed into the bolt holes 67, 67. Figure 5 The first housing portion 6 and the second housing portion 7 are joined to each other using bolts B.

[0160] like Figure 6 As shown, the second housing part 7 has an annular base 71 .

[0161] like Figure 4 As shown, the base portion 71 is a plate-shaped member having a thickness W71 in the direction of the rotation axis X.

[0162] A through hole 70 is provided in the center of the base portion 71 so as to penetrate the base portion 71 in the thickness direction.

[0163] A cylindrical wall portion 72 surrounding the through hole 70 and a peripheral wall portion 73 surrounding the cylindrical wall portion 72 at a distance therefrom are provided on the surface of the base portion 71 on the opposite side (left side in the figure) from the first case portion 6 .

[0164] A protrusion 73 a that protrudes toward the rotation axis X is provided at the front end of the peripheral wall portion 73 . The protrusion 73 a is provided over the entire circumference of the rotation axis X.

[0165] like Figure 6 As shown, three support holes 71a for the pinion shaft 44 are opened on the outer diameter side of the peripheral wall portion 73. The three support holes 71a are arranged in the circumferential direction around the rotation axis X at intervals.

[0166] Three slits 710 penetrating the base portion 71 in the thickness direction are provided on the inner diameter side of the peripheral wall portion 73 .

[0167] The slit 710 is formed in an arc shape along the inner periphery of the peripheral wall portion 73 when viewed from the direction of the rotation axis X. The slit 710 is formed in a predetermined angular range in the circumferential direction around the rotation axis X.

[0168] In the second case portion 7 , the slits 710 are arranged at intervals from each other 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 71 a in the circumferential direction around the rotation axis X.

[0169] Three protruding walls 711 are provided between adjacent slits 710, 710 in the circumferential direction around the rotation axis X. The protruding walls 711 protrude in a direction away from the first housing portion 6. The protruding walls 711 extend linearly in the radial direction of the rotation axis X. The protruding walls 711 are provided across the outer diameter side peripheral wall portion 73 and the inner diameter side cylindrical wall portion 72.

[0170] The three protruding walls 711 are arranged at intervals from each other in the circumferential direction around the rotation axis X. The protruding walls 711 are arranged with a phase shift of approximately 45 degrees relative to the slit 710 in the circumferential direction around the rotation axis X.

[0171] Bolt receiving portions 76 , 76 recessed toward the first case portion 6 are provided between adjacent support holes 71 a , 71 a in the circumferential direction around the rotation axis X on the outer diameter side of the peripheral wall portion 73 .

[0172] A bolt insertion hole 77 is formed inside the bolt receiving portion 76. The insertion hole 77 penetrates the base portion 71 in the thickness direction (rotation axis X direction).

[0173] like Figure 4 As shown, a connection portion 74 that protrudes toward the first case portion 6 is provided on the surface of the base portion 71 on the first case portion 6 side (right side in the figure).

[0174] The connection portions 74 are provided in the same number as the connection beams 62 on the first case portion 6 side.

[0175] A support groove 75 for supporting the pinion mating shaft 51 is provided on the front end surface of the coupling portion 74 .

[0176] An arc portion 741 is provided on the inner diameter side (rotation axis X side) of the coupling portion 74 so as to follow the outer circumference of the pinion mating gear 52 .

[0177] The outer periphery of the pinion mating gear 52 is supported on the arc portion 741 via the spherical washer 53 .

[0178] In the second housing 7 , an annular washer 55 supporting the back surface of the side gear 54B is placed on the surface 71 b of the base 71 . A cylindrical wall 540 is provided on the back surface of the side gear 54B. The washer 55 is externally inserted into the wall 540 .

[0179] The base 71 of the second housing 7 is provided with a guide portion 78. The guide portion 78 protrudes toward the first housing 6 (right side in the figure). The guide portion 78 is provided so as to align with the boss portion 616 (see FIG. 1 ) of the first housing 6. Figure 6 ) the same number.

[0180] like Figure 4 As shown, in a cross-section along the axis X1, the pinion shaft 44 is inserted from the first housing portion 6 side into the support hole 71a of the guide portion 78. The pinion shaft 44 is positioned by a positioning pin P while being restricted from rotating about the axis X1.

[0181] In this state, the small-diameter gear portion 432 of the stepped pinion 43 externally inserted into the pinion shaft 44 abuts against the guide portion 78 from the axis X1 direction with the washer Wc interposed therebetween.

[0182] In the differential case 50, a bearing B2 is externally inserted into the cylindrical wall portion 72 of the second case portion 7. The bearing B2 externally inserted into the cylindrical wall portion 72 is held by the support portion 145 of the fourth case 14. The cylindrical wall portion 72 of the differential case 50 is rotatably supported by the fourth case 14 via the bearing B2.

[0183] The drive shaft DB that passes through the opening 145 a of the fourth housing 14 is inserted into the support portion 145 in the direction of the rotation axis X. The drive shaft DB is rotatably supported by the support portion 145 .

[0184] A lip seal RS is fixed to the inner periphery of the opening 145a. A lip portion (not shown) of the lip seal RS elastically contacts the outer periphery of the cylindrical wall portion 540 of the side gear 54B externally inserted on the drive shaft DB.

[0185] As a result, the gap between the outer periphery of the cylindrical wall portion 540 of the side gear 54B and the inner periphery of the opening 145 a is sealed.

[0186] like Figure 2 As shown, the first case portion 6 of the differential case 50 is supported by the plate member 8 via the bearing B3 externally inserted into the cylindrical wall portion 611 .

[0187] The drive shaft DA that has passed through the insertion hole 130 a of the third housing 13 is inserted into the first case portion 6 from the rotation axis X direction.

[0188] The drive shaft DA is provided so as to cross the motor shaft 20 of the motor 2 and the inner diameter side of the sun gear 41 of the planetary reduction gear 4 in the direction of the rotation axis X.

[0189] like Figure 4 As shown, side gears 54A, 54B are spline-fitted to the outer circumferences of the front ends of drive shafts DA, DB inside the differential case 50. The side gears 54A, 54B and the drive shafts DA, DB are coupled so as to be rotatable integrally about the rotation axis X.

[0190] In this state, the side gears 54A and 54B are arranged to face each other with a gap therebetween in the direction of the rotation axis X. The connecting portion 510 of the pinion mating shaft 51 is located between the side gears 54A and 54B.

[0191] In this embodiment, three pinion mating shafts 51 extend radially outward from the connecting portion 510. A pinion mating gear 52 is supported on each of the pinion mating shafts 51. The pinion mating gears 52 are assembled to a side gear 54A located on one side of the rotation axis X direction and a side gear 54B located on the other side, with their teeth meshing with each other.

[0192] exist Figure 2The oil storage portion OP is formed in the lower portion of the gear chamber Sb of the fourth case 14, and stores the oil OL for lubrication. The lower portion side of the differential case 50 is positioned inside the oil storage portion OP.

[0193] In the present embodiment, the oil OL is stored to the height at which the web 62 is positioned inside the oil storage portion OP when the web 62 is positioned at the lowermost side.

[0194] The oil OL of the oil storage portion OP is scooped up by the differential case 50 that rotates around the rotation axis X when transmission of the output rotation of the motor 2 is performed.

[0195] Figure 7 to Figure 12 is a view that illustrates the oil retaining portion 15.

[0196] Figure 7 is a plan view of the fourth case 14 as viewed from the third case 13 side.

[0197] Figure 8 is a perspective view of the oil retaining portion 15 as viewed obliquely from above. Figure 7

[0198] Figure 9 is a plan view of the fourth case 14 as viewed from the third case 13 side, and is a view that indicates the state in which the differential case 50 is disposed.

[0199] Figure 10 is a perspective view of the oil retaining portion 15 as viewed obliquely from above. Figure 9

[0200] Figure 11 is a view that illustrates the A-A section in Figure 9

[0201] Figure 12 is a view that illustrates the positional relationship of the oil retaining portion 15 and the differential case 50 (the first case portion 6, the second case portion 7) when the power transmission device 1 is viewed from above.

[0202] Further, in Figure 7 and Figure 9 , hatching is indicated in order to make the positions of the joint portion 142 and the support wall portion 146 of the fourth case 14 clear.

[0203] Figure 7 and Figure 9 , the plumb line VL is a plumb line VL that takes the state in which the power transmission device 1 is disposed on the vehicle as a reference. The plumb line VL is orthogonal to the rotation axis X as viewed in the direction of the rotation axis X. In addition, the horizontal line HL is a horizontal line HL that takes the state in which the power transmission device 1 is disposed on the vehicle as a reference. The horizontal line HL is orthogonal to the rotation axis X and the plumb line VL as viewed in the direction of the rotation axis X.

[0204] As​​​Figure 7 As shown, a support wall portion 146 that surrounds the opening portion 145a in the center at intervals is provided in the fourth case 14 as viewed in the direction of the rotation axis X. The inner side (rotation axis X) side of the support wall portion 146 becomes the accommodation portion 140 of the differential case 50.

[0205] A space of the oil baffle portion 15 and a space of the breather chamber 16 are formed in the upper portion in the fourth case 14.

[0206] In the support wall portion 146 of the fourth case 14, a communication port 147 that communicates the oil baffle portion 15 with the accommodation portion 140 of the differential case 50 is provided in a region that intersects the vertical line VL.

[0207] The oil baffle portion 15 and the breather chamber 16 are respectively located on one side (left side in the drawing) and the other side (right side in the drawing) across the vertical line VL orthogonal to the rotation axis X.

[0208] The oil baffle portion 15 is disposed at a position that deviates from the vertical line VL that passes through the rotation center (rotation axis X) of the differential case 50. As shown, Figure 12 When the oil baffle portion 15 is viewed from above, the oil baffle portion 15 is disposed at a position that deviates from directly above the differential case 50.

[0209] As shown, Figure 8 The oil baffle portion 15 is formed so as to reach the paper plane depth side more than the support wall portion 146. A support stage portion 151 (shelf portion) is protrusively provided toward the paper plane near side in the lower edge of the oil baffle portion 15. The support stage portion 151 is provided in a range that is more toward the paper plane near side than the support wall portion 146 and is more toward the paper plane depth side than the joint portion 142 of the fourth case 14.

[0210] As shown, Figure 7 As viewed in the direction of the rotation axis X, the communication port 147 is formed by cutting a portion of the support wall portion 146 on the vertical line VL side (right side in the drawing) of the oil baffle portion 15. The communication port 147 communicates the oil baffle portion 15 and the accommodation portion 140 of the differential case 50.

[0211] As viewed in the direction of the rotation axis X, the communication port 147 is provided in a range that cuts the vertical line VL from the breather chamber 16 side (right side in the drawing) toward the oil baffle portion 15 side (left side in the drawing).

[0212] As shown, Figure 9 In the present embodiment, as viewed from the third case 13 side when the vehicle on which the power transmission device 1 is mounted is traveling forward, the differential case 50 rotates in the counterclockwise direction CCW around the rotation axis X.

[0213] Therefore, the oil retaining portion 15 is located on the downstream side in the rotation direction of the differential case 50. Also, the left side across the vertical line VL is wider than the right side in terms of the width in the circumferential direction of the communication port 147. The left side across the vertical line VL is the downstream side in the rotation direction of the differential case 50, and the right side is the upstream side. Thus, most of the oil OL lifted by the differential case 50 rotating around the rotation axis X can flow into the oil retaining portion 15.

[0214] In addition, as shown in Figure 12 , the outer peripheral position of the rotation track of the second shaft portion 446 of the pinion shaft 44 and the outer peripheral position of the rotation track of the large-diameter gear portion 431 are offset in the radial direction of the rotation axis X. The outer peripheral position of the rotation track of the second shaft portion 446 is located on the inner diameter side than the outer peripheral position of the rotation track of the large-diameter gear portion 431.

[0215] Therefore, there is a spatial margin on the outer diameter side of the second shaft portion 446. By providing the oil retaining portion 15 using this space, efficient use of the space inside the main body case 10 can be performed.

[0216] As shown in Figure 12 , the second shaft portion 446 protrudes toward the depth side of the small-diameter gear portion 432 as viewed from the motor 2. The peripheral member of the second shaft portion 446 (for example, the guide portion 78 of the differential case 50 supporting the second shaft portion 446) becomes a position close to the oil retaining portion 15.

[0217] Therefore, the supply of the oil OL (lubricating oil) from this peripheral member to the oil retaining portion 15 can be smoothly performed.

[0218] As shown in Figure 8 , the end portion of the oil hole 151a on the outer diameter side is provided on the depth side of the support platform portion 151. The oil hole 151a extends toward the inner diameter side inside the fourth case 14. The end portion of the oil hole 151a on the inner diameter side is provided on the inner periphery of the support portion 145.

[0219] As shown in Figure 2 , in the support portion 145, the end portion of the oil hole 151a on the inner diameter side is provided between the lip seal RS and the bearing B2.

[0220] As shown in Figure 10 and Figure 12 , the oil guide 152 is loaded on the support platform portion 151.

[0221] The oil guide 152 has a capturing portion 153 and a guide portion 154 extending from the capturing portion 153 toward the first case 11 side (the paper face side in front). Figure 10

[0222] As shown in Figure 12 ​As shown, the support platform portion 151 is disposed at a position coinciding with a portion of the differential case 50 (the first housing portion 6, the second housing portion 7) on the radially outer side of the rotation axis X so as to avoid interference with the stepped pinion 43 (the large-diameter gear portion 431) as viewed from above.

[0223] As viewed from the radial direction of the rotation axis X, the capturing portion 153 is disposed at a position coinciding with the second shaft portion 446 of the pinion shaft 44. In addition, the guide portion 154 is disposed at a position coinciding with the first shaft portion 445 of the pinion shaft 44 and the large-diameter gear portion 431.

[0224] Therefore, when the differential case 50 rotates around the rotation axis X, the oil OL lifted by the differential case 50 moves toward the capturing portion 153 and the guide portion 154 side.

[0225] A wall portion 153a extending in a direction away from the support platform portion 151 (an upward direction) is provided at the outer periphery of the capturing portion 153. A portion of the oil OL lifted by the differential case 50 rotating around the rotation axis X is stored in the oil guide 152.

[0226] At the depth side (the paper depth side) of the capturing portion 153, a cutout portion 155 is provided at the wall portion 153a. Figure 10

[0227] The cutout portion 155 is disposed at a region opposite the oil hole 151a. A portion of the oil OL stored in the capturing portion 153 is discharged from the portion of the cutout portion 155 toward the oil hole 151a.

[0228] The guide portion 154 is inclined downward as it moves away from the capturing portion 153. Wall portions 154a, 154a are provided at both sides in the width direction of the guide portion 154. The wall portions 154a, 154a are provided over the entire length in the long direction of the guide portion 154. The wall portions 154a, 154a are connected to the wall portion 153a surrounding the outer periphery of the capturing portion 153.

[0229] Therefore, a portion of the oil OL stored in the capturing portion 153 is also discharged to the guide portion 154 side.

[0230] As shown, the guide portion 154 extends toward the second case 12 side at a position avoiding interference with the differential case 50. The front end 154b of the guide portion 154 opposes the oil hole 126a provided at the wall portion 120 of the second case 12 with a gap in the rotation axis X direction. Figure 11 A boss portion 126 surrounding the oil hole 126a is provided at the outer periphery of the wall portion 120. One end of the pipe 127 is fitted into the boss portion 126 from the rotation axis X direction.

[0231] A boss portion 126 surrounding the oil hole 126a is provided at the outer periphery of the wall portion 120. One end of the pipe 127 is fitted into the boss portion 126 from the rotation axis X direction.

[0232] ​The pipe 127 passes through the outside of the second case 12 and reaches the third case 13. The other end of the pipe 127 communicates with an oil hole 136a (refer to Figure 2 ) of a cylindrical connecting wall 136 provided to the third case 13.

[0233] A part of the oil OL scooped up by the differential case 50 rotating around the rotation axis X reaches the oil retaining portion 15. The oil OL is supplied to the inner space Sc of the connecting wall 136 through the guide portion 154 and the pipe 127.

[0234] As shown in Figure 2 , a radial oil passage 137 communicating with the inner space Sc is provided in the third case 13.

[0235] The radial oil passage 137 extends from the inner space Sc to the radially lower side. The radial oil passage 137 communicates with an axial oil passage 138 provided in the joint portion 132.

[0236] The axial oil passage 138 is connected to an oil reservoir portion 128 provided to the lower portion of the second case 12 via a communication hole 112a provided to the joint portion 112 of the first case 11.

[0237] The oil reservoir portion 128 penetrates the peripheral wall portion 121 in the rotation axis X direction. The oil reservoir portion 128 is connected to an oil storage portion OP provided to the gear chamber Sb of the fourth case 14.

[0238] In the gear chamber Sb, the plate member 8 of a circular plate shape is provided in a direction orthogonal to the rotation axis X. As described above, the plate member 8 (plate) divides the gear chamber Sb in the fourth case 14 into a first gear chamber Sb1 (first space) on the differential case 50 side and a second gear chamber Sb2 (second space) on the motor 2 side.

[0239] In the lower portion of the gear chamber Sb of the fourth case 14, a cooling chamber CR (second chamber) is provided adjacent to the gear chamber Sb.

[0240] Figure 13 is an enlarged view of the lower portion of the fourth case 14 around the cooling chamber CR.

[0241] Figure 14 is a view of the cooling chamber CR as viewed from the peripheral wall portion 141 side (left side of the paper of Figure 2 ).

[0242] Figure 15 is a view showing a state in which the cover portion 9 of the cooling chamber CR is removed.

[0243] Figure 16 is a view explaining circulation of the coolant CL.

[0244] Figure 17 is a view showing the structure of the cover portion 9.

[0245] Figure 18 is a view explaining assembly of the spacer 94 to the cover portion 9.

[0246] Figure 19 is a view explaining flow of the coolant CL in the cooling chamber CR.

[0247] As Figure 13 shown, the cooling chamber CR is provided with the outer cover portion 143 and the cover portion 9. The coolant CL is introduced into the inside of the cooling chamber CR. As described above, the oil reservoir portion OP is formed in the lower portion of the gear chamber Sb. The coolant CL introduced into the cooling chamber CR cools the oil OL stored in the oil reservoir portion OP.

[0248] The outer cover portion 143 is a wall portion covering the outer circumferential surface of the support wall portion 146. As Figure 15 shown, the outer cover portion 143 constitutes an arc shape along the cylindrical support wall portion 146 when viewed in the direction of the rotation axis X. The outer cover portion 143 can be formed integrally with the support wall portion 146 by, for example, casting.

[0249] As Figure 13 shown, the outer cover portion 143 extends in the direction of the rotation axis X. The base end portion 143a of the outer cover portion 143 provided on the one end side in the direction of the rotation axis X is connected to the joint portion 142 in the lower portion of the fourth case 14. The joint portion 143b of the cover portion 9 described later is provided on the opposite end of the base end portion 143a.

[0250] The inner wall surface 143c of the outer cover portion 143 opposes the outer circumferential surface of the support wall portion 146 via a gap. As Figure 15 shown, the inner space that becomes an arc shape when viewed in the direction of the rotation axis X is partitioned between the outer cover portion 143 and the support wall portion 146. This arc-shaped inner space becomes the inside of the cooling chamber CR. Further, the opening portion CRo of the cooling chamber CR is formed by the joint portion 143b of the outer cover portion 143 and the joint portion 146b of the support wall portion 146.

[0251] The cover portion 9 closes the opening portion CRo of the cooling chamber CR. As Figure 14 shown, the cover portion 9 is a plate-shaped member that becomes an arc shape when viewed in the direction of the rotation axis X.

[0252] The inlet port 92a and the outlet port 92b are provided in the vicinity of the one end 91a and the other end 91b in the circumferential direction of the rotation axis X of the cover portion 9, respectively. The inlet port 92a and the outlet port 92b are holes that penetrate the cover portion 9 in the direction of the rotation axis X, and a pipe PI is connected to each port. As Figure 16 shown, the inlet port 92a of the cover portion 9 is connected to the outlet port 124b of the cooling passage CP via the pipe PI.

[0253] The coolant CL flows in the cooling passage CP (refer toFigure 2 ) flows through the interior of the cooling passage CP to cool the motor 2 and is then discharged from the outlet 124b of the cooling passage CP. The coolant CL is introduced into the cooling chamber CR from the inlet 92a of the cooling chamber CR through the pipe PI.

[0254] like Figure 16 As shown in FIG. 1 , the cooling liquid CL introduced into the cooling chamber CR flows inside the cooling chamber CR. Thus, the supporting wall portion 146 (see FIG. 1 ) of the cooling chamber CR is formed. Figure 15 ) cooling. By also using it as the gear chamber Sb (refer to Figure 13 ) is cooled, and the oil OL stored in the oil storage portion OP in the gear chamber Sb is cooled.

[0255] like Figure 16 As shown, the coolant CL flowing in the cooling chamber CR is discharged from the discharge port 92b. The discharged coolant CL is introduced into the inlet 124a of the cooling passage CP again through a pipe (not shown) provided inside the vehicle. Figure 2 ).

[0256] like Figure 13 As shown in FIG. 1 , the end surface 93 of the cover 9 faces the interior of the cooling chamber CR. A spacer 94 is mounted on the end surface 93 so as to protrude toward the interior of the cooling chamber CR. Figure 17 As shown in FIG. 1 , the spacer 94 is an arc-shaped component similar to the cover 9. The spacer 94 is installed between the inlet 92a and the outlet 92b of the cover 9. Figure 13 As shown, the spacer 94 has a thickness in the radial direction of the rotation axis X. The cover 9 and the spacer 94 may be made of different materials. The cover 9 may be made of metal, for example, and the spacer 94 may be made of resin, for example.

[0257] like Figure 18 As shown, a protrusion 95 for attaching the spacer 94 to the cover 9 is provided on the spacer 94. A hole 93a is provided on the end surface 93 of the cover 9, into which the protrusion 95 can be inserted. An annular groove 93b is formed on the inner circumference of the hole 93a of the cover 9. The protrusion 95 functions as an engaging portion that can be inserted into the hole 93a in the axis Y direction (one direction). The number and location of the holes 93a corresponding to the protrusion 95 are not limited, and a plurality of holes 93a can be provided so that the spacer 94 can be stably attached to the cover 9.

[0258] The protrusion 95 is formed with a slit 95a cut from the distal end toward the proximal end of the protrusion 95 along the axis Y. For example, four slits 95a can be formed in the circumferential direction around the axis Y at 90° intervals.

[0259] Hooks 95b are formed at the tips of protrusions 95, which are divided by slits 95a, and project radially outward from axis Y. Protrusions 95 are sized to match the inner diameter α of hole 93a. Hooks 95b are larger than the inner diameter α of hole 93a and are sized to fit into annular groove 93b in hole 93a.

[0260] When installing the cover 9, the protrusion 95 is pressed in one direction, that is, toward the bottom of the hole 93a. Figure 18 The movement of protrusion 95 is indicated by the double-dashed line. When the hook portion 95b at the tip of protrusion 95 contacts hole 93a, it bends due to the compressive force from the outer periphery, shrinking the width of slit 95a. The shrinking of slit 95a reduces the outer diameter of the tip of hook portion 95b. When it reaches a size that matches the inner diameter α of hole 93a, protrusion 95 is inserted into hole 93a. When the tip of protrusion 95 reaches annular groove 93b, hook portion 95b fits into the annular groove 93b, and slit 95a returns to its original width. This engages protrusion 95 with hole 93a, and spacer 94 is attached to cover 9.

[0261] Note that this mounting method is just an example, and the spacer 94 may be mounted to the cover 9 by other mounting methods such as bolt fixing.

[0262] like Figure 13 As shown, the cooling chamber CR is formed so as to span the first gear chamber Sb1 and the second gear chamber Sb2 when viewed in the radial direction of the rotation axis X. The first gear chamber Sb1 is located on the opening CRo side, which is the front side (left side in the figure) of the cooling chamber CR. The second gear chamber Sb2 is located on the back side (right side in the figure) of the cooling chamber CR, away from the opening CRo.

[0263] When the cover 9 closes the opening CRo of the cooling chamber CR, the spacer 94 is located on the front side of the cooling chamber CR (left side in the figure). The spacer 94 has a thickness in the radial direction of the rotation axis X, and thus functions as a volume reducing portion that reduces the volume of the front side of the cooling chamber CR. Figure 19 As shown by the dashed line, without the spacer 94, the coolant CL flowing from the inlet 92a to the outlet 92b tends to stagnate near the front of the cooling chamber CR and is less likely to reach the rear end of the cooling chamber CR. On the other hand, when the spacer 94 is included as in the embodiment, the spacer 94 extends toward the front of the cooling chamber CR. As a result, as shown by the dashed line, the coolant CL is guided not only toward the front of the cooling chamber CR but also toward the rear end. In other words, the spacer 94 functions as a guide member that directs the coolant CL introduced from the inlet 92a toward the direction away from the opening CR0.

[0264] like Figure 13As shown, in the first gear chamber Sb1, located in the upper portion near the front side (left side in the figure) of the cooling chamber CR, the oil OL is lifted by the differential case 50, resulting in intense circulation of the oil OL. On the other hand, in the second gear chamber Sb2, located in the upper portion near the back side (right side in the figure) of the cooling chamber CR, the oil OL circulates more smoothly. Therefore, by providing a spacer 94, the coolant CL is directed toward the back side of the cooling chamber CR, allowing the coolant CL to gradually cool the oil OL in the second gear chamber Sb2. This improves the overall cooling efficiency of the oil OL in the oil reservoir OP.

[0265] The operation of the power transmission device 1 having the above-described structure will be described.

[0266] like Figure 1 As shown, in the power transmission device 1 , a planetary reduction gear 4 , a differential mechanism 5 , and drive shafts DA and DB are provided along a transmission path of output rotation of a motor 2 .

[0267] like Figure 2 As shown, when the motor 2 is driven and the rotor core 21 rotates about the rotation axis X, rotation is input to the sun gear 41 of the planetary reduction gear 4 via the motor shaft 20 that rotates integrally with the rotor core 21 .

[0268] like Figure 3 As shown, in the planetary reduction gear 4, the sun gear 41 serves as an input portion for the output rotation of the motor 2. The differential case 50 supporting the stepped pinion 43 serves as an output portion for the input rotation.

[0269] When the sun gear 41 rotates about the rotation axis X by the input rotation, the stepped pinion 43 (large diameter gear portion 431 , small diameter gear portion 432 ) rotates about the axis X1 by the rotation input from the sun gear 41 side.

[0270] Here, the small-diameter gear portion 432 of the stepped pinion 43 meshes with the ring gear 42 fixed to the inner periphery of the fourth case 14. Therefore, the stepped pinion 43 revolves around the rotation axis X while rotating around the axis X1.

[0271] Here, the outer diameter R2 of the small-diameter gear portion 432 of the stepped pinion 43 is smaller than the outer diameter R1 of the large-diameter gear portion 431 (see Figure 3 ).

[0272] As a result, the differential case 50 (the first case portion 6 and the second case portion 7 ) supporting the stepped pinion gear 43 rotates about the rotation axis X at a rotation speed lower than the rotation input from the motor 2 side.

[0273] Therefore, the rotation of the sun gear 41 input to the planetary reduction gear 4 is greatly reduced in speed by the stepped pinion 43. The reduced rotation is output to the differential case 50 (differential mechanism 5).

[0274] The differential case 50 rotates around the rotation axis X by the input rotation, and thereby the drive shafts DA and DB meshing with the pinion gear 52 in the differential case 50 rotate around the rotation axis X. As a result, the left and right drive wheels W and W (see FIG. 1 ) of the vehicle equipped with the power transmission device 1 are rotated. Figure 1 ) is rotated by the transmitted rotational driving force.

[0275] like Figure 2 As shown, an oil reservoir OP storing lubricating oil OL is formed inside the fourth case 14. The oil OL stored in the oil reservoir OP is lifted up by the differential case 50 rotating about the rotation axis X when the output rotation of the motor 2 is transmitted.

[0276] The stirred oil OL lubricates the meshing portions between the sun gear 41 and the large-diameter gear portion 431 , the meshing portions between the small-diameter gear portion 432 and the ring gear 42 , and the meshing portions between the pinion mating gear 52 and the side gears 54A, 54B.

[0277] like Figure 9 As shown, the differential case 50 rotates in the counterclockwise direction CCW around the rotation axis X when viewed from the third case 13 side.

[0278] An oil sparging portion 15 is provided above the fourth case 14. This portion is located downstream of the differential case 50 in the rotational direction. Most of the oil OL lifted by the differential case 50 flows into the oil sparging portion 15. The oil OL is then supplied to an oil guide 152 mounted on a support platform 151 within the oil sparging portion 15.

[0279] Thus, most of the oil OL lifted by the differential case 50 flows into the oil retaining portion 15. A portion of the oil OL falls due to gravity and returns to and is stored in the oil storage portion OP. Figure 13 As shown, a cooling chamber CR is provided below the oil reservoir OP, through which coolant CL flows. While the temperature of the oil OL lifted by the differential case 50 rises, the oil OL returning to the oil reservoir OP is cooled by heat exchange with the coolant CL. The cooled oil OL is then lifted again by the differential case 50 and used for lubrication.

[0280] The cooling fluid CL of the oil OL in the cooling oil reservoir OP is stored in the cooling passage CP (refer to Figure 2 ) and then introduced into the cooling chamber CR. Specifically, in the embodiment, the coolant CL used to cool the motor 2 is also used to cool the oil OL, eliminating the need to provide a new coolant CL for cooling the oil OL. Furthermore, in the embodiment, by cooling the motor 2, which has a higher cooling priority, before the oil OL, appropriate thermal management of the entire power transmission device 1 can be achieved.

[0281] As described above, the power transmission apparatus 1 of the present embodiment has the following structure.

[0282] (1) The power transmission apparatus 1 has:

[0283] a motor 2;

[0284] a planetary reduction gear 4 and a differential mechanism 5 (a gear mechanism) connected downstream of the motor 2;

[0285] a fourth case 14 (a case) that houses the planetary reduction gear 4 and the differential mechanism 5.

[0286] A gear chamber Sb (a first chamber) that houses the planetary reduction gear 4, the differential mechanism 5, and the oil OL is formed in the fourth case 14.

[0287] A cooling chamber CR (a second chamber) that is adjacent to the gear chamber Sb and into which the coolant CL is introduced is formed in the fourth case 14.

[0288] The gear chamber Sb that houses the planetary reduction gear 4 and the differential mechanism 5 is formed in the fourth case 14. The oil OL that lubricates the planetary reduction gear 4 and the differential mechanism 5 is housed in the gear chamber Sb. The cooling chamber CR is formed adjacent to the gear chamber Sb. The support wall portion 146 that divides the gear chamber Sb and the cooling chamber CR is cooled by the coolant CL introduced into the cooling chamber CR. The oil OL in the gear chamber Sb can be cooled using the cooled support wall portion 146. The present embodiment can improve the cooling efficiency of the oil OL. Furthermore, the cooling chamber CR is formed in the fourth case 14 itself. Compared to a case in which a member separate from the fourth case 14 is provided to cool the support wall portion 146, the cooling efficiency can be improved, and the power transmission apparatus 1 can also be made compact.

[0289] (2) The cooling chamber CR is formed adjacent to a lower portion of the gear chamber Sb.

[0290] The oil OL, after being agitated by the planetary reduction gear 4, is stored in an oil storage portion OP of a lower portion of the gear chamber Sb. By forming the cooling chamber CR adjacent to the lower portion of the gear chamber Sb, the oil OL of the oil storage portion OP can be directly cooled, and thus the cooling efficiency can be improved.

[0291] (3) The cooling chamber CR is configured in an arc shape when viewed in the direction of the rotation axis X (an axial direction).

[0292] By configuring the cooling chamber CR in an arc shape, the cooling chamber CR can be formed in a manner along the support wall portion 146 of the cylindrical fourth case 14, and thus the power transmission apparatus 1 can be prevented from being made large.

[0293] (4) In the power transmission apparatus 1,

[0294] A cover portion 9 is provided with an opening portion CRo of the cooling chamber CR.

[0295] The cover portion 9 has a cooling liquid CL introduction port 92a and a cooling liquid CL discharge port 92b.

[0296] The power transmission apparatus 1 further has a partition 94 (guiding member) that guides the cooling liquid CL introduced from the introduction port 92a in a direction away from the opening portion CRo.

[0297] In a case where the cover portion 9 of the cooling chamber CR is provided with the cooling liquid CL introduction port 92a and the discharge port 92b, it is easy to form a flow of the cooling liquid CL in the vicinity of the cover portion 9. Therefore, by providing the partition 94, the cooling liquid CL is guided in a manner to flow in a direction away from the depth side of the opening portion CRo, and it is possible to improve the cooling efficiency.

[0298] (5) In the power transmission apparatus 1,

[0299] The plate member 8 (plate) has a first gear chamber Sb1 (first space) that divides the gear chamber Sb into a region where the planetary reduction gear 4 and the differential mechanism 5 are arranged, and a second gear chamber Sb2 (second space) where the planetary reduction gear 4 is not arranged.

[0300] The partition 94 guides the cooling liquid CL from the first gear chamber Sb1 side toward the second gear chamber Sb2 side.

[0301] In the first gear chamber Sb1 where the planetary reduction gear 4 is arranged, the flow of the oil OL is intense. On the other hand, in the second gear chamber Sb2 where the planetary reduction gear 4 is not arranged, the flow of the oil OL is relatively calm. By forming the flow of the cooling liquid CL toward the second gear chamber Sb2 side by the partition 94, it is possible to slowly cool the oil OL on the second gear chamber Sb2 side, and it is possible to improve the cooling efficiency.

[0302] (6) The partition 94 is attached to the cover portion 9.

[0303] Thereby, it is possible to simplify the assembly process of the cover portion 9 and the partition 94 to the opening portion CRo.

[0304] (7) The partition 94 is attached to the cover portion 9 by inserting a protrusion 95 (engagement portion) that can be inserted in the axial direction Y (one direction) into the cover portion 9.

[0305] Thereby, it is possible to easily attach the partition 94 to the cover portion 9, and it is possible to simplify the assembly process.

[0306] (8) In the power transmission apparatus 1, the cooling liquid CL that has cooled the motor 2 is introduced into the cooling chamber CR.

[0307] By using the coolant CL of the motor 2 also for cooling of the oil OL of the gear chamber Sb, it is not necessary to prepare a new coolant CL. In addition, after the motor 2 is cooled, the oil OL of the gear chamber Sb is cooled. Thereby, it is possible to give priority to cooling of the motor 2, and therefore, it is possible to appropriately perform thermal management as a whole of the power transmission device 1.

[0308] The above describes embodiments of the present application, but the present application is not limited to the modes shown in the embodiments. It is possible to make appropriate changes within the scope of the technical idea of the application.

[0309] Explanation of Reference Numerals

[0310] 1: Power transmission device

[0311] 14: Fourth case

[0312] 146: Support wall portion

[0313] 2: Motor

[0314] 4: Planetary reduction gear (gear mechanism)

[0315] 5: Differential mechanism (gear mechanism)

[0316] 8: Plate member (plate)

[0317] 9: Cover portion

[0318] 92a: Inlet

[0319] 92b: Outlet

[0320] 94: Spacer (guide member)

[0321] 95: Protrusion

[0322] CL: Coolant

[0323] CR: Cooling chamber (second chamber)

[0324] CRo: Opening portion

[0325] OL: Oil

[0326] Sb: Gear chamber (first chamber)

[0327] Sb1: First gear chamber (first space)

[0328] Sb2: Second gear chamber (second space)

[0329] X: Rotation axis

[0330] Y: Axis line

Claims

1. A power transmission device comprising: motor; a gear mechanism connected to a downstream portion of the motor and lubricated with oil; Box; The housing includes a wall portion covering an outer periphery of the gear mechanism and a cover portion covering an outer periphery of the wall portion. A cooling chamber for introducing cooling liquid is formed between the wall portion and the outer cover portion. An oil storage portion is provided for storing the oil formed in a lower portion of a gear chamber for storing the oil and the gear mechanism. The cooling chamber formed adjacent to the lower portion of the gear chamber has a portion overlapping with the gear mechanism when viewed in the radial direction and a portion overlapping with the gear mechanism when viewed in the axial direction.

2. The power transmission device according to claim 1, wherein: The cooling chamber has an arc-shaped portion when viewed from the axial direction. The arc-shaped portion includes a portion that overlaps with the gear mechanism when viewed from the radial direction and a portion that overlaps with the gear mechanism when viewed from the axial direction.

3. The power transmission device according to claim 1, wherein: The cooling chamber has a portion that overlaps with a space between the gear mechanism and the motor when viewed from the radial direction.

4. The power transmission device according to claim 3, wherein: The space does not overlap with the gear mechanism.

5. The power transmission device according to claim 1, wherein: The gear mechanism includes a planetary gear mechanism having a stepped pinion including a small-diameter gear portion and a large-diameter gear portion, and a pinion shaft supporting the pinion. In the cooling chamber, a portion overlapping with the pinion shaft when viewed in the radial direction includes a portion overlapping with the large-diameter gear portion of the stepped pinion when viewed in the axial direction.

6. A power transmission device comprising: motor; a gear mechanism connected to a downstream portion of the motor and lubricated with oil; plate; Box; The housing includes a wall portion covering an outer periphery of the gear mechanism and a cover portion covering an outer periphery of the wall portion. A cooling chamber for introducing cooling liquid is formed between the wall portion and the outer cover portion. A receiving portion for receiving the oil and the gear mechanism is formed on the inner periphery of the wall portion. The plate divides the storage portion into a first space where the gear mechanism is arranged and a second space where the gear mechanism is not arranged. When viewed from the radial direction, the cooling chamber has a portion overlapping with the second space.

7. The power transmission device according to claim 6, wherein: The cooling chamber includes a guide portion for guiding the coolant from the first space side to the second space side.

8. A power transmission device comprising: motor; a gear mechanism connected to a downstream portion of the motor and lubricated with oil; Box; The housing includes a wall portion covering an outer periphery of the gear mechanism and a cover portion covering an outer periphery of the wall portion. A cooling chamber is formed between the wall portion and the outer cover portion, into which a coolant is introduced through an inlet and discharged through an outlet. A spacer is provided in the cooling chamber so as to protrude in the axial direction away from the inlet. The front end of the spacer on the axial side faces the wall on the axial side of the cooling chamber with a gap therebetween. When viewed from the axial direction, the inlet and the outlet are arranged so as to sandwich the spacer in the circumferential direction.

9. The power transmission device according to claim 8, wherein: The spacer has an arc-shaped portion.

10. The power transmission device according to claim 8, wherein: The power transmission device has a plate, The plate divides the inner periphery of the wall into a first space where the gear mechanism is arranged and a second space where the gear mechanism is not arranged. When viewed from the radial direction, the cooling chamber has a portion overlapping with the second space.

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