CN111033969B

CN111033969B - Drive device

Info

Publication number: CN111033969B
Application number: CN201880050820.8A
Authority: CN
Inventors: 石川勇树; 中松修平
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-08-25
Filing date: 2018-06-19
Publication date: 2022-04-15
Anticipated expiration: 2038-06-19
Also published as: CN111033969A; WO2019039060A1

Abstract

The drive device has: a rotor having a motor shaft and a rotor core; a stator; and a housing having a housing portion capable of storing oil, the motor shaft having: a shaft main body portion extending along a central axis; a cylindrical rotor core holding portion located radially outside the shaft main body portion; a connecting portion connecting an outer peripheral surface of the shaft main body portion and an inner peripheral surface of the rotor core holding portion in a radial direction; a 1 st oil passage extending in the axial direction inside the shaft main body and opened at an end in the axial direction; a plurality of 2 nd oil passages branched from the 1 st oil passage and extending in a radial direction inside the connection portion; and a plurality of 3 rd oil passages branched from the 2 nd oil passage, extending in the axial direction inside the connecting portion, and opened at surfaces of the connecting portion facing one side and the other side in the axial direction, respectively, a flow passage sectional area of the 2 nd oil passage being smaller than a flow passage sectional area of the 1 st oil passage, and a flow passage sectional area of the 3 rd oil passage being smaller than a flow passage sectional area of the 2 nd oil passage.

Description

Drive device

Technical Field

The present invention relates to a drive device.

Background

There is known an electric motor in which a coolant is circulated in a housing for lubrication and cooling of a stator, a rotor, and the like. For example, japanese laid-open patent publication No. 2003-324901 discloses a motor mounted on a vehicle.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2003-324901

Disclosure of Invention

Problems to be solved by the invention

In the motor described above, the cooling liquid is circulated through the passages inside the rotor, and is discharged from the plurality of pump outlets to cool the coils. However, the pressure of the coolant discharged from the plurality of pump outlets tends to become uneven, and it is difficult to uniformly cool the coil.

An object of one embodiment of the present invention is to provide a driving device in which uniformity of cooling of a coil is improved.

Means for solving the problems

According to one aspect of the present invention, there is provided a driving device including: a rotor having a motor shaft disposed along a central axis extending in one direction and a rotor core fixed to the motor shaft; a stator that is opposed to the rotor with a gap therebetween in a radial direction; and a housing having a housing portion that houses the rotor and the stator and is capable of storing oil, the motor shaft including: a shaft main body portion extending along a central axis; a cylindrical rotor core holding portion located radially outward of the shaft main body portion; a connecting portion connecting an outer peripheral surface of the shaft body portion and an inner peripheral surface of the rotor core holding portion in a radial direction; a 1 st oil passage extending in the axial direction inside the shaft main body and opened at an end in the axial direction; a plurality of 2 nd oil passages branched from the 1 st oil passage and extending in a radial direction inside the connection portion; and a plurality of 3 rd oil passages branched from the 2 nd oil passage, extending in the axial direction inside the connecting portion, and opened at surfaces of the connecting portion facing one side and the other side in the axial direction, the 2 nd oil passage having a flow passage cross-sectional area smaller than that of the 1 st oil passage, and the 3 rd oil passage having a flow passage cross-sectional area smaller than that of the 2 nd oil passage.

Effects of the invention

According to an aspect of the present invention, for example, a driving device in which uniformity of cooling of a coil is improved is provided.

Drawings

Fig. 1 is a sectional view showing a driving device of an embodiment.

Fig. 2 is a partial sectional view showing a structure of a modification.

Detailed Description

Fig. 1 is a sectional view showing a driving device of the present embodiment. The Z-axis direction shown in the figure is a vertical direction Z in which the positive side is an upper side and the negative side is a lower side. In the present embodiment, the vertical direction Z is the vertical direction of the drawing. In the following description, the vertical upper side is simply referred to as "upper side", and the vertical lower side is simply referred to as "lower side".

As shown in fig. 1, the drive device 1 of the present embodiment includes a housing 10, a rotor 20, a rotation detection unit 80, a stator 30, a pump unit 40, and

bearings

70 and 71, wherein the rotor 20 includes a motor shaft 20a disposed along a center axis J1 extending in one direction.

The center axis J1 extends in the left-right direction in fig. 1. That is, in the present embodiment, the left-right direction in fig. 1 corresponds to one direction. In the following description, a direction parallel to the axial direction of the center axis J1 is simply referred to as an "axial direction", a radial direction about the center axis J1 is simply referred to as a "radial direction", and a circumferential direction about the center axis J1 is simply referred to as a "circumferential direction". The left side of fig. 1 in the axial direction is referred to as "one axial side", and the right side of fig. 1 in the axial direction is referred to as "the other axial side".

The housing 10 includes a main body 11, an inner lid 12, and an outer lid 13. In the present embodiment, the body portion 11, the inner lid portion 12, and the outer lid portion 13 are separate members. The body 11 has a bottomed tubular shape that is open on one axial side. The main body 11 has a bottom portion 11a, a main body tube portion 11b, and a bearing holding portion 11 c. The bottom 11a has a radially expanded annular plate shape. The main body tube portion 11b is cylindrical and extends from the radially outer edge portion of the bottom portion 11a to one axial side. The bearing holding portion 11c is cylindrical and protrudes axially from the inner edge of the bottom portion 11 a. The bearing holding portion 11c holds the bearing 71 on the inner peripheral surface.

The inner lid 12 is attached to one axial side of the body 11. The inner lid 12 includes an annular plate 12a, an outer cylinder 12b, an inner cylinder 12c, and a bearing holder 12 e. The annular plate portion 12a has an annular plate shape extending in the radial direction. The inner cover 12 covers one axial side of the stator 30 with an annular plate portion 12 a. The annular plate 12a has an opening 12f at a lower end thereof, which penetrates the annular plate 12a in the axial direction. The opening 12f is connected to the inside of the housing 10.

The outer tube portion 12b is cylindrical and extends from the radially outer edge of the annular plate portion 12a to the other axial side. The other axial end of the outer tube 12b is fixed in contact with one axial end of the main tube 11 b. The inner tube portion 12c is cylindrical and extends from the radially inner edge portion of the annular plate portion 12a to the other axial side.

The bearing holding portion 12e includes: an annular portion 101 that extends radially inward from the other axial end of the inner cylindrical portion 12 c; and a cylindrical portion 102 that protrudes from the radially inner edge of the annular portion toward the other axial end.

The inner lid 12 has a 2 nd recess 12g recessed from one axial side of the inner lid 12 toward the other axial side. The inner surface of the 2 nd recessed portion 12g includes the inner peripheral surface of the inner tube portion 12c and the axial one-side surface of the annular portion 101. In the present embodiment, the surface on one side in the axial direction of inner lid portion 12 is the surface on one side in the axial direction of annular portion 101. The inner surface of the 2 nd recessed portion 12g includes a radial inner surface of the inner tube portion 12c and an axial surface of the annular portion 101.

The cylindrical portion 102 of the bearing holding portion 12e has a cylindrical shape protruding from the radially inner end edge of the annular portion 101 toward the other axial side. The bearing holding portion 12e holds the bearing 70 on the inner circumferential surface of the cylindrical portion 102.

The housing 10 has a housing portion 14 formed of a main body portion 11 and an inner lid portion 12. The housing 14 houses the rotor 20 and the stator 30. The stator 30 is fixed to the inner surface of the body portion 11. The rotor 20 is disposed radially inward of the stator 30.

The stator 30 is opposed to the rotor 20 with a gap in the radial direction. The stator 30 includes a stator core 31 and a plurality of coils 32 attached to the stator core 31. The stator core 31 has an annular shape centered on the central axis J1. The outer peripheral surface of the stator core 31 is fixed to the inner peripheral surface of the main body tube portion 11 b. The stator core 31 faces the radially outer side of the rotor core 22, which will be described later, with a gap therebetween. The coil 32 protrudes toward one side and the other side in the axial direction of the stator core 31.

The housing 14 can store oil O therein. The oil O is stored in the lower region of the housing portion 14 in the vertical direction. In the present specification, the "lower region of the housing portion in the vertical direction" includes a portion located below the center of the housing portion in the vertical direction Z.

In the present embodiment, the liquid surface OS of the oil O stored in the storage portion 14 is located above the opening 12 f. Thus, the oil O stored in the storage portion 14 always flows through the opening 12 f. The liquid surface OS of the oil O fluctuates due to the oil O sucked up by the pump section 40, but is disposed below the rotor 20 at least when the rotor 20 rotates. This can prevent the oil O from becoming rotational resistance of the rotor 20 when the rotor 20 rotates.

The outer lid portion 13 is attached to one axial side of the inner lid portion 12. The outer lid portion 13 includes an outer lid body portion 13a and a plug body portion 13 b. The outer lid main body portion 13a expands in the radial direction. The outer lid body 13a has a lid portion 13c and a protruding portion 13 d. The cover plate portion 13c has a circular plate shape extending in the radial direction. The radially outer edge of the cover plate 13c is fixed to the radially outer edge of the annular plate 12 a. The other axial surface of the cover plate 13c is in contact with the one axial surface of the annular plate 12 a. The protruding portion 13d protrudes from the center of the cover plate portion 13c toward the other side in the axial direction. The protruding portion 13d is inserted into the inner cylindrical portion 12c from one axial side. The protruding portion 13d is disposed at a distance from one axial side of the annular portion 101 of the bearing holding portion 12 e.

The outer lid body 13a has a 1 st recess 13e and a 2 nd through hole 13 f. The 1 st recess 13e is recessed from one axial side surface of the outer lid body 13a toward the other axial side surface. The 1 st recess 13e is provided in the center of the outer lid body 13a, spanning the lid portion 13c and the protruding portion 13 d. The 2 nd through hole 13f penetrates from the bottom surface of the 1 st recess 13e to the other surface of the projection 13d in the axial direction. That is, the 2 nd through hole 13f penetrates from the bottom surface of the 1 st recess 13e to the inside of the housing 10. The 2 nd through hole 13f opens in the 2 nd recess 12 g. Thereby, the 2 nd through hole 13f connects the inside of the 1 st recess 13e and the inside of the 2 nd recess 12 g. The center axis J1 passes through the 2 nd through hole 13 f.

The plug portion 13b is fitted into the 1 st recess 13e and fixed to the outer lid body portion 13 a. The plug portion 13b closes an opening of the 1 st recess 13e on one axial side. The bolt portion 13b covers one axial side of the motor shaft 20 a. That is, the outer cover 13 covers one axial side of the motor shaft 20 a. The plug portion 13b has a flange portion 13g protruding radially outward at one end in the axial direction. The flange portion 13g contacts one axial surface of the cover plate portion 13 c. The bolt portion 13b is positioned in the axial direction by the flange portion 13 g.

In the outer lid portion 13, an internal gear 43 and an external gear 42 are housed between the outer lid body portion 13a and the plug body portion 13 b. In the present embodiment, the pump section 40 is configured by a portion of the outer cover section 13 that houses the outer gear 42 and the inner gear 43. In the present embodiment, the pump section 40 is a trochoid pump. A cylindrical mounting member 50 that connects the pump section 40 and the oil passage in the motor shaft 20a is inserted into the through hole of the external gear 42.

The plug portion 13b has a suction-side oil passage 40a and a pump-out-side oil passage 40 b. The suction-side oil passage 40a connects the opening 12f and the suction port of the pump section 40 via an oil passage, not shown, provided in the outer cover 13. The pump-out side oil passage 40b connects the pump outlet of the pump section 40 and the through hole of the mounting member 50.

The rotor 20 has: motor shaft 20a, rotor core 22, 1 st end plate 24, and 2 nd end plate 25. The motor shaft 20a includes a shaft body 21a, a rotor core holding portion 21b, a connecting portion 21c, and a mounting member 50. The shaft body portion 21a, the rotor core holding portion 21b, and the connecting portion 21c are one member.

The shaft body portion 21a has a cylindrical shape extending in the axial direction around the center axis J1. The rotor core holding portion 21b is cylindrical and surrounds the radially outer side of the shaft body portion 21a around the center axis J1. The axial length of the rotor core holding portion 21b is shorter than the axial length of the shaft body portion 21 a. The connecting portion 21c extends annularly radially outward from the axial center portion of the shaft body 21a in a region where the shaft body 21a and the rotor core holding portion 21b overlap each other when viewed in the radial direction, and connects the shaft body 21a and the rotor core holding portion 21b in the radial direction. The axial length of the connecting portion 21c is shorter than the axial length of the shaft body portion 21a and the axial length of the rotor core holding portion 21 b. Therefore, the outer peripheral surface 201a of the shaft body 21a and the inner peripheral surface 201b of the rotor core holding portion 21b are radially opposed to each other on one axial side of the connecting portion 21 c. Further, on the other axial side of the connecting portion 21c, the outer peripheral surface 202a of the shaft body portion 21a and the inner peripheral surface 202b of the rotor core holding portion 21b are opposed in the radial direction.

The motor shaft 20a has a 1 st shaft recess 21A opened to one side in the axial direction and a 2 nd shaft recess 21B opened to the other side in the axial direction.

The 1 st shaft recess 21A is an annular groove portion that is open to one axial side and extends in the circumferential direction. The 1 st shaft recess 21A has the outer peripheral surface 201A of the shaft body 21A and the inner peripheral surface 201b of the rotor core holding portion 21b as side surfaces, and has the axial one-side surface 201c of the connecting portion 21c as a bottom surface.

In the 1 st shaft recess 21A, the inner peripheral surface 201b of the rotor core holding portion 21b is inclined radially outward toward the open end of the rotor core holding portion 21b on one axial side. The inner peripheral surface 201b of the rotor core holding portion 21b has a curved inclined surface portion 201d at an end portion on the opening side in the axial direction. The inclined surface portion 201d is a curved surface inclined radially outward as it goes toward one axial side.

The 2 nd shaft recess 21B is an annular groove portion that is open on the other axial side and extends in the circumferential direction. The 2 nd shaft recess 21B has the outer peripheral surface 202a of the shaft body 21a and the inner peripheral surface 202B of the rotor core holding portion 21B as side surfaces, and has the one axial surface 202c of the connecting portion 21c as a bottom surface. In the 2 nd shaft recess 21B, the inner peripheral surface 202B of the rotor core holding portion 21B is inclined radially outward toward the other axial end opening of the rotor core holding portion 21B.

The shaft body 21a is rotatably supported by a bearing 70 located on one axial side of the connecting portion 21c and a bearing 71 located on the other axial side of the connecting portion 21 c. The

bearings

70 and 71 are, for example, ball bearings.

In the present embodiment, a part of the bearing holding portion 12e that holds the bearing 70 overlaps the rotor core holding portion 21b when viewed in the radial direction. With this configuration, the axial length of the drive device 1 can be shortened, and the thickness can be reduced.

In the present embodiment, the cylindrical portion 102 of the bearing holding portion 12e has a shape in which the diameter increases toward the one axial side in the vicinity of the opening of the one axial side of the rotor core holding portion 21 b. That is, the outer peripheral surface of the bearing holding portion 12e is an inclined surface inclined radially outward from the inside of the rotor core holding portion 21b toward the axially outward side. The outer peripheral surface of the bearing holding portion 12e has a curved surface shape following the inclined surface portion 201d of the rotor core holding portion 21b facing each other with a gap therebetween.

The annular portion 101 of the bearing holding portion 12e and the flange portion 203 axially face each other. That is, the bearing holding portion 12e faces the surface of the rotor core holding portion 21b facing the axial direction.

The shaft body 21a has an output portion 21e at the other axial end.

The rotation detecting unit 80 is disposed on one axial side of the bearing 70. The rotation detecting unit 80 detects rotation of the rotor 20. In the present embodiment, the rotation detecting unit 80 is, for example, a VR (Variable Reluctance) type resolver. The rotation detecting portion 80 is disposed radially inward of the inner cylindrical portion 12 c. The resolver rotor of the rotation detecting unit 80 is fixed to one axial end of the shaft body 21a, and the resolver stator is fixed to the inner periphery of the inner cylindrical portion 12 c. The rotation detecting unit 80 may be configured by combining a hall element or an MR (magnetic resistance) element with a magnet.

The shaft body 21a has a 1 st oil passage 61, and the 1 st oil passage 61 is formed by a bottomed hole that is open at one end in the axial direction of the shaft body 21a and extends to the other end in the axial direction. The other axial end of the 1 st oil passage 61 is closed. In the present embodiment, the inner edge of the 1 st oil passage 61 has a circular shape centered on the center axis J1 in a cross section perpendicular to the axial direction.

The rotor core holding portion 21b is a portion where the rotor core 22 is mounted in the motor shaft 20 a. The rotor core 22 is annular and fixed to the shaft body 21 a. The rotor core 22 is fitted to the outer peripheral surface of the cylindrical rotor core holding portion 21 b. Rotor core 22 includes a plurality of rotor magnets, not shown. The plurality of rotor magnets are arranged along the circumferential direction of rotor core 22.

The rotor core holding portion 21b has a flange portion 203 extending radially outward from one end portion in the axial direction. The flange portion 203 has a female screw portion 203a penetrating in the axial direction. First end plate 1 is disposed so as to be sandwiched between flange 203 and rotor core 22 in the axial direction. The 2 nd end plate 25 is disposed in contact with the other axial surface of the rotor core 22. The 1 st end plate 24 and the 2 nd end plate 25 have a radially expanded annular plate shape. However, the 1 st end plate 24 may be absent.

The rotor core 22 and the 2 nd end plate 25 have through holes that penetrate the rotor core 22 and the 2 nd end plate 25 in the axial direction. Rotor core 22 is fixed to the rotor core holding portion by bolts 204. Bolts 204 are inserted into through holes of rotor core 22 and 2 nd end plate 25. The male screw portion of the bolt 204 is fastened to the female screw portion of the flange portion 203.

In the present embodiment, the rotor core holding portion 21b has the flange portion 203, and thus the rotor core 22 can be positioned and fixed in the axial direction. By providing the flange portion 203 with a female screw portion, the bolt 204 can be fastened without using a nut. The tip of the bolt 204 slightly protrudes from the axial surface of the flange 203, and therefore the flow of the oil O along the surface of the flange 203 is not easily inhibited.

The mounting member 50 is fixed to one axial side of the shaft body 21a by a cap-shaped coupling member 51. The connecting member 51 has a through hole penetrating the connecting member 51 in the axial direction, and the mounting member 50 is inserted into the through hole of the connecting member 51. The through hole of the mounting member 50 constitutes a part of the 1 st oil passage 61 of the shaft body portion 21a, and is connected to the pump-out side oil passage 40b of the pump portion 40. The mounting member 50 is supported rotatably in the 2 nd through hole 13f so as to extend to one axial side than the shaft body portion 21 a.

The 1 st oil passage 61 is branched into a plurality of 2 nd oil passages 62 at the axial center portion of the shaft main body portion 21 a. The plurality of 2 nd oil passages 62 radially extend from the 1 st oil passage 61. The number of the 2 nd oil passages 62 is, for example, 2 to 16. The 2 nd oil passage 62 may be inclined or curved with respect to the radial direction as long as it can guide the oil from the 1 st oil passage 61 to the outside in the radial direction.

The 2 nd oil passage 62 extends from the 1 st oil passage 61 in the radial direction, penetrates the connecting portion 21c and the rotor core holding portion 21b, and opens on the outer peripheral surface of the rotor core holding portion 21 b. Therefore, a part of the inner peripheral surface of the rotor core 22 is exposed to the end portion on the radially outer side of the 2 nd oil passage 62. This also enables the rotor core 22 to be cooled by the oil O.

The 2 nd oil passage 62 branches into two 3

rd oil passages

63A, 63B inside the connection portion 21 c. The 3 rd oil passage 63A extends axially from a branch point with the 2 nd oil passage 62, and opens on an axial one-side surface 201c of the connecting portion 21 c. The 3 rd oil passage 63B extends from a branch point with the 2 nd oil passage 62 to the other axial side, and opens on the other axial side surface 202c of the connection portion 21 c. The 3

rd oil passages

63A, 63B may be inclined or curved with respect to the axial direction as long as oil can be guided from the 2 nd oil passage 62 in the axial direction.

In the present embodiment, the 3

rd oil passages

63A, 63B open at the radial center portion of the connecting portion 21 c. The corners of the bottom surfaces of the 1 st shaft recess 21A and the 2 nd shaft recess 21B are likely to have rounded shapes, and the drill is likely to slide in the vicinity of the corners, and therefore, drilling is difficult. In the present embodiment, the center portion in the radial direction of the connecting portion 21c is likely to be a relatively flat surface, and therefore, the hole forming process is likely to be performed. Further, since machining is easy, the accuracy of the 3

rd oil passages

63A and 63B can be easily improved.

The shaft body 21a further includes 4

th oil passages

64A and 64B extending from the 1 st oil passage 61 to the

bearings

70 and 71. The 4 th oil passage 64A is branched from the axial center portion of the 1 st oil passage 61 and extends obliquely outward in the radial direction toward one radial side. The 4 th oil passage 64A is open to the outer peripheral surface of the shaft body 21a at a position facing the other surface in the axial direction of the bearing 70. The connection position of the 4 th oil passage 64A and the 1 st oil passage 61 is on one axial side of the connection position of the 2 nd oil passage 62 and the 1 st oil passage 61. The number of the 4 th oil passages 64A is, for example, 1 to 8.

The 4 th oil passage 64B is branched from the other axial end of the 1 st oil passage 61 and extends radially outward. The connection position of the 4 th oil passage 64B and the 1 st oil passage 61 is on the other axial side than the bearing 71. The 4 th oil passage 64B extends radially outward from the 1 st oil passage 61. The 4 th oil passage 64B is open at a position facing the other surface in the axial direction of the bearing 71 on the outer peripheral surface of the shaft body 21 a. The number of the 4 th oil passages 64B is, for example, 1 to 8.

In the drive device 1 of the present embodiment, the pump section 40 is driven via the motor shaft 20 a. In the drive device 1, when the rotor 20 rotates to rotate the motor shaft 20a, the external gear 42 fixed to the motor shaft 20a rotates. Thereby, the internal gear 43 meshing with the external gear 42 rotates, and the oil O is sucked up from the lower portion of the housing portion 14 through the suction-side oil passage 40 a. The oil O sucked between the external gear 42 and the internal gear 43 is discharged to the pump-out side oil passage 40 b. The oil O discharged to the pump-out side oil passage 40b flows into the 1 st oil passage 61.

The oil O flowing into the 1 st oil passage 61 flows into the plurality of 2 nd oil passages 62 branched at the center portion in the axial direction. The oil O flowing into the 2 nd oil passage 62 flows into the two 3

rd oil passages

63A and 63B branched at the center portion in the radial direction of the 2 nd oil passage 62. The oil O flowing into the 3 rd oil passage 63A flows into the 1 st shaft recess 21A from the opening of the surface 201c facing the one axial side of the connecting portion 21 c.

The oil O flowing into the 1 st shaft recess 21A moves radially outward by centrifugal force and reaches the inner circumferential surface 201b of the rotor core holding portion 21 b. The oil O on the inner circumferential surface 201b moves to one axial side along the inclination of the inner circumferential surface 201 b. The oil O reaching the one axial end of the inner peripheral surface 201b flows along the inclined surface portion 201d radially outward in the moving direction, and flows out to the outside of the 1 st shaft recess 21A.

In the present embodiment, the inner peripheral surface 201b is an inclined surface, and therefore the oil O does not stay on the inner peripheral surface 201b and smoothly moves toward the coil 32. Further, the end portion of the inner circumferential surface 201b has the inclined surface portion 201d, so that the moving direction of the oil O can be smoothly rotated in the radial direction from the axial direction, and the main splashing direction of the oil O can be directed toward the coil 32.

The oil O flowing out of the 1 st shaft recess 21A is splashed radially outward directly from the axial end of the inner peripheral surface 201b, or is splashed after moving radially outward along the surface of the flange portion 203. The splashed oil O adheres to the coils 32 of the stator 30 to cool the coils 32.

In the present embodiment, since the rotor core holding portion 21b has the flange portion 203, the oil O flowing out radially outward from the inclined surface portion 201d at the opening end of the 1 st shaft recess portion 21A can be smoothly splashed radially outward along the surface on one side in the axial direction of the flange portion 203.

In the present embodiment, the bearing holding portion 12e is disposed at a position facing the inner peripheral surface 201b and the flange portion 203 of the rotor core holding portion 21 b. With this configuration, even the oil O that splashes from the 1 st shaft recess 21A to one side in the axial direction and collides with the bearing holding portion 12e can smoothly rotate in the moving direction from the axial direction to the radial direction in accordance with the surface shape of the bearing holding portion 12 e. This enables the oil O to be efficiently supplied to the coil 32.

The oil O flowing from the 2 nd oil passage 62 into the 3 rd oil passage 63B flows into the 2 nd shaft recess 21B from the opening of the surface 202c on the other axial side of the connecting portion 21 c. The oil O flowing into the 2 nd shaft recess 21B moves radially outward by centrifugal force and reaches the inner peripheral surface 202B of the rotor core holding portion 21B. The oil O on the inner peripheral surface 202B moves to the other axial side along the inclination of the inner peripheral surface 202B, and flows out from the other axial end of the inner peripheral surface 201B to the outside of the 2 nd shaft recessed portion 21B. In the present embodiment, the inner peripheral surface 202b is an inclined surface, so that the oil O smoothly moves toward the coil 32 without being accumulated on the inner peripheral surface 202 b.

The oil O flowing out of the 2 nd shaft recess 21B splashes directly outward in the radial direction from the end portion on the other axial side of the inner peripheral surface 202B, or splashes after moving outward in the radial direction along the surface of the 2 nd end plate 25. The splashed oil O adheres to the coils 32 of the stator 30 to cool the coils 32.

In the drive device 1 of the present embodiment, as shown in fig. 1, the flow path cross-sectional area of the oil path decreases in the order of the 1 st oil path 61, the 2 nd oil path 62, and the 3

rd oil paths

63A and 63B. Since the plurality of 2 nd oil passages 62 are branched from one 1 st oil passage 61 and the two 3

rd oil passages

63A and 63B are branched from one 2 nd oil passage 62, the oil passages are narrowed down each time the oil passages are branched, and the oil O can be fed at a constant pressure while maintaining the cross-sectional area of the flow passage of the entire oil passages. This can prevent the flow of the oil O from being deviated to one of the branched oil passages or from being disturbed by the air mixed in the oil passage. As a result, a predetermined amount of oil O can be supplied to the coil 32, and the coil 32 can be sufficiently cooled.

In the present embodiment, the flow path cross-sectional area of the 1 st oil path 61 may be 90% or more and 110% or less of the sum of the flow path cross-sectional areas of the plurality of branched 2 nd oil paths 62. By suppressing the rate of change in the flow path cross-sectional area before and after branching to 10% or less, pressure fluctuations in the oil O flowing from the 1 st oil path 61 to the 2 nd oil path 62 can be suppressed. This can suppress variation in the amount of oil O supplied to the coil 32 in the circumferential direction.

In the present embodiment, the flow passage cross-sectional area of the 2 nd oil passage 62 may be 90% to 110% of the sum of the flow passage cross-sectional areas of the branched 3

rd oil passages

63A and 63B. By suppressing the rate of change in the flow path cross-sectional area before and after branching to 10% or less, pressure fluctuations of the oil O flowing from the 2 nd oil path 62 to the two 3

rd oil paths

63A, 63B can be suppressed. This can suppress variation in the amount of oil O supplied to the coil 32 between one side and the other side in the axial direction.

A part of the oil O flowing through the 1 st oil passage 61 flows out through the 4 th oil passage 64A from the opening of the outer peripheral surface of the shaft body 21a, and is supplied to the bearing 70. The other part of the oil O flows out from the 1 st oil passage 61 through the 4 th oil passage 64B from the opening of the outer peripheral surface of the shaft main body 21a, and is supplied to the bearing 71. Thereby, the oil O is used as a lubricant for the

bearings

70, 71.

In the present embodiment, the 4

th oil passages

64A, 64B are branched from the 1 st oil passage 61. Therefore, the relationship between the flow passage cross-sectional areas may be considered as the flow passage cross-sectional areas of the 4

th oil passages

64A and 64B. That is, the 1 st oil passage 61 may have a flow passage cross-sectional area that is 90% to 110% of the sum of the flow passage cross-sectional areas of the 2 nd oil passage 62 and the 4

th oil passages

64A and 64B branched from the 1 st oil passage 61. This can suppress pressure fluctuations in the respective oil passages branched from the 1 st oil passage 61, and can suppress variations in the amount of oil O pumped.

As described above, the pump unit 40 is driven by the rotation of the motor shaft 20a, and the oil O stored in the casing 10 is sucked up by the pump unit 40 and can be supplied to the rotor 20, the stator 30, and the

bearings

70 and 71. This enables the rotor 20 and the stator 30 to be cooled by the oil O stored in the housing 10, and improves the lubricity between the

bearings

70 and 71 and the shaft body 21 a. The oil O supplied to the stator 30 and the

bearings

70 and 71 falls down in the housing 14 and is stored again in a region below the housing 14. This enables circulation of the oil O in the housing 14.

The present invention is not limited to the above embodiment, and other configurations may be adopted.

Fig. 2 is a partial sectional view showing a rotor 20A according to a modification.

As shown in fig. 2, the rotor core holding portion 21b of the rotor 20A has

fin portions

210 and 211 extending from the connection position with the connection portion 21c toward the opening ends of the rotor core holding portion 21b on both sides in the axial direction, respectively, on the inner circumferential surface 201b and the inner circumferential surface 202 b. The rotor 20A has the same structure as the rotor 20 of the embodiment except for the

fin portions

210 and 211. The

fins

210, 211 are, for example, strip-shaped projections extending in the axial direction, and are arranged in parallel in the circumferential direction on the inner

circumferential surfaces

201b, 202 b. With this configuration, the oil O located in the 1 st and 2 nd shaft recesses 21A, 21B can be smoothly moved in the axial direction by the

fin portions

210, 211. Thereby, the oil O is efficiently supplied to the coil 32. In the above configuration, only one of the

fins

210 and 211 may be provided.

The external gear 42 may be directly fixed to the shaft body portion 21a without the intermediary of the mounting member 50. In this case, the 1 st oil passage 61 may be provided only inside the shaft main body portion 21a, for example. The mounting member 50 may be fixed to the outer peripheral surface of the shaft body 21 a.

The rotor core 22 may be fixed to the outer peripheral surface of the rotor core holding portion 21b by press fitting or the like. In this case, the flange portion 203 of the rotor core holding portion 21b, the 1 st end plate 24, and the 2 nd end plate 25 may not be provided.

The application of the driving device of the above embodiment is not particularly limited. In addition, the above-described structures may be appropriately combined within a range not inconsistent with each other.

Description of the reference symbols

1: a drive device; 10: a housing; 11: a main body portion; 12 e: a bearing holding portion; 14: a storage section; 20: a rotor; 20 a: a motor shaft; 21 a: a shaft main body portion; 21 b: a rotor core holding portion; 21 c: a connecting portion; 22: a rotor core; 30: a stator; 61: the 1 st oil path; 62: a 2 nd oil passage; 63A, 63B: a 3 rd oil path; 64A, 64B: a 4 th oil path; 70. 71: a bearing; 201a, 202 a: an outer peripheral surface; 201b, 202 b: an inner peripheral surface; 201c, 202 c: a surface of the connecting portion facing the axial direction; 201 d: an inclined plane part; 203: a flange portion; j1: a central axis; o: and (3) oil.

Claims

1. A drive device, comprising:

a rotor having a motor shaft disposed along a central axis extending in one direction and a rotor core fixed to the motor shaft;

a stator that is opposed to the rotor with a gap therebetween in a radial direction; and

a housing having a housing portion that houses the rotor and the stator and is capable of storing oil,

the motor shaft has:

a shaft main body portion extending along a central axis;

a cylindrical rotor core holding portion located radially outward of the shaft main body portion;

a connecting portion connecting an outer peripheral surface of the shaft body portion and an inner peripheral surface of the rotor core holding portion in a radial direction;

a 1 st oil passage extending in the axial direction inside the shaft main body and opened at an end in the axial direction;

a plurality of 2 nd oil passages branched from the 1 st oil passage and extending in a radial direction inside the connection portion; and

a plurality of 3 rd oil passages branched from the 2 nd oil passage, extending in the axial direction inside the connecting portion, and opened at surfaces of the connecting portion facing one side and the other side in the axial direction, respectively,

the flow path sectional area of the 2 nd oil passage is smaller than the flow path sectional area of the 1 st oil passage,

a flow path sectional area of the 3 rd oil passage is smaller than a flow path sectional area of the 2 nd oil passage,

the motor shaft has a 1 st shaft recess opened toward one side in the axial direction and a 2 nd shaft recess opened toward the other side in the axial direction,

the 1 st shaft recess has an outer peripheral surface of the shaft body and an inner peripheral surface of the rotor core holding portion as side surfaces,

the 1 st shaft recess has a surface on one side in the axial direction of the connecting portion as a bottom surface,

an opening of the 3 rd oil passage extending from a branch point with the 2 nd oil passage to one side in the axial direction is opened at a bottom surface of the 1 st shaft recess,

the 2 nd shaft recess has an outer peripheral surface of the shaft body and an inner peripheral surface of the rotor core holding portion as side surfaces,

the 2 nd shaft recess has a surface on the other axial side of the connecting portion as a bottom surface,

an opening of the 3 rd oil passage extending from a branch point with the 2 nd oil passage to the other side in the axial direction is opened at a bottom surface of the 2 nd shaft recess,

the 2 nd oil passage extends in a radial direction inside the connecting portion and the rotor core holding portion, and opens on an outer peripheral surface of the rotor core holding portion.

2. The drive apparatus according to claim 1,

the flow path cross-sectional area of the 1 st oil path is 90% to 110% of the sum of the flow path cross-sectional areas of the 2 nd oil paths.

3. The drive apparatus according to claim 1,

the flow path cross-sectional area of the 2 nd oil passage is 90% to 110% of the sum of the flow path cross-sectional areas of the 3 rd oil passages.

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

the drive device further includes a bearing for supporting the shaft main body portion,

the motor shaft has a 4 th oil passage, and the 4 th oil passage branches from the 1 st oil passage and opens at a position facing the bearing.

5. The drive device according to any one of claims 1 to 3,

the 3 rd oil passage opens at a radially central portion of the connecting portion.

6. The drive device according to any one of claims 1 to 3,

the inner peripheral surface of the rotor core holding portion is inclined radially outward from a connecting position with the connecting portion toward an axial opening end of the rotor core holding portion.

7. The drive device according to any one of claims 1 to 3,

the inner peripheral surface of the rotor core holding portion has a curved inclined surface portion at an end portion of an opening side in the axial direction.

8. The drive device according to any one of claims 1 to 3,

the rotor core holding portion has a fin portion extending from a connection position with the connection portion toward an axial opening end of the rotor core holding portion on an inner peripheral surface of the rotor core holding portion.

9. The drive device according to any one of claims 1 to 3,

the rotor core holding portion has a flange portion extending radially outward from an axial opening end.

10. The drive device according to any one of claims 1 to 3,

the drive device has a bearing for supporting the shaft main body part,

the housing has a bearing holding portion that holds the bearing,

at least a part of the bearing holding portion overlaps with the rotor core holding portion when viewed in the radial direction.

11. The drive apparatus according to claim 10,

the outer peripheral surface of the bearing holding portion is an inclined surface inclined radially outward from the inside of the rotor core holding portion toward the bearing holding portion.

12. The drive apparatus according to claim 11,

the bearing holding portion has a surface facing an axial surface of the rotor core holding portion.