Drive device

Abstract

[Problem] To reduce the size of a drive device having a cooling path. [Solution] A drive device according to the present invention includes a motor, an inverter, a power transmission mechanism for transmitting power of the motor to drive wheels, and a housing for accommodating the motor, the inverter, and the power transmission mechanism. The housing has a motor accommodation part, an inverter accommodation part, and a power transmission mechanism accommodation part, the power transmission mechanism has an output shaft for outputting power from the motor, and the rotation axis of the output shaft and the rotation axis of the motor are placed in parallel with each other with an interval in the front-rear direction. When viewed from above the vehicle, the inverter accommodation part is offset from the rotation axis of the motor and overlaps with the rotation axis of the output shaft. When viewed from the rotation-axis direction of the motor, the bottom of the inverter accommodation part is positioned below a horizontal line passing through the upper end of the motor in the upper-lower direction, and the inverter accommodation part is provided with a first cooling path for cooling the inverter. When viewed from the rotation-axis direction of the motor, the first cooling path is placed between the inverter and the output shaft in the upper-lower direction.

Description

Drive unit

[0001] The present invention relates to a drive device.

[0002] Patent Document 1 discloses a drive device having a cooling path for cooling a motor and an inverter.

[0003] Japanese Patent Application Laid-Open No. 2020-18094

[0004] The cooling passage is provided inside the housing that houses the motor and inverter, so depending on the layout of the motor and inverter, providing the cooling passage may result in an increase in the size of the drive unit.

[0005] Therefore, there is a demand for miniaturization of drive devices having cooling paths.

[0006] A drive device in one aspect of the present invention is a drive device comprising: a motor which is a drive source for a vehicle; an inverter which supplies current to the motor; a power transmission mechanism which transmits power from the motor to drive wheels; and a housing which accommodates the motor, the inverter, and the power transmission mechanism, wherein the housing has: a motor accommodating section which accommodates the motor; an inverter accommodating section which accommodates the inverter and is attached to an upper part of the motor accommodating section in a vertical direction based on an installation state of the drive device on the vehicle; and a power transmission mechanism accommodating section which accommodates the power transmission mechanism and is disposed adjacent to the motor accommodating section in a direction of a rotation axis of the motor, the power transmission mechanism having an output shaft which outputs power from the motor, the rotation axis of the output shaft and the rotation axis of the motor being disposed parallel to each other with a gap in the fore-and-aft direction of the vehicle, and when viewed from above the vehicle, the inverter accommodating section is offset from the rotation axis of the motor and overlaps with the rotation axis of the output shaft, When viewed from the direction of the rotational axis of the motor, the bottom of the inverter accommodating section is located below a horizontal line passing through the upper end of the motor in the vertical direction, and a first cooling path for cooling the inverter is provided in the inverter accommodating section, and when viewed from the direction of the rotational axis of the motor, the first cooling path is provided between the inverter and the output shaft in the vertical direction.

[0007] According to one aspect of the present invention, a drive unit having a cooling passage can be made smaller.

[0008] FIG. 1 is a schematic diagram illustrating the arrangement of a drive unit in a vehicle. FIG. 2 is a schematic diagram illustrating a general configuration of the drive unit. FIG. 3 is a diagram illustrating a second cooling path. FIG. 4 is a diagram illustrating the second cooling path. FIG. 5 is a diagram illustrating a bulging wall portion. FIG. 6 is a diagram illustrating an inverter case. FIG. 7 is a diagram illustrating the inverter case. FIG. 8 is a diagram illustrating the inverter case. FIG. 9 is a diagram illustrating the inverter case. FIG. 10 is a diagram illustrating a first cooling path. FIG. 11 is a diagram illustrating the first cooling path. FIG. 12 is a diagram illustrating the first cooling path. FIG. 13 is a diagram illustrating the first cooling path. FIG. 14 is a diagram illustrating the first cooling path. FIG. 15 is a diagram illustrating the first cooling path. FIG. 16 is a diagram illustrating the first cooling path. FIG. 17 is a diagram illustrating the flow of cooling water. FIG. 18 is a diagram illustrating the flow of cooling water. FIG. 19 is a diagram illustrating the flow of cooling water.

[0009] First, definitions of terms used in this specification will be explained. "Housing" refers to a device that houses a motor, gears, and an inverter. The housing is made up of one or more cases.

[0010] The term "motor" refers to a rotating electric machine having a motor function and / or a generator function.

[0011] When it is stated that an element B (component, part, etc.) is connected to an element A (component, part, etc.), an element B (component, part, etc.) is connected downstream of an element A (component, part, etc.), or an element B (component, part, etc.) is connected upstream of an element A (component, part, etc.), it means that the elements A and B are connected so that power can be transmitted. The power input side is the upstream side, and the power output side is the downstream side. Furthermore, the elements A and B may be connected via another element (a clutch, another gear mechanism, etc.).

[0012] "Overlapping when viewed in a predetermined direction" means that multiple elements are lined up in a predetermined direction, and is synonymous with "overlapping in a predetermined direction." The "predetermined direction" is, for example, the axial direction, the radial direction, the direction of gravity, the vehicle traveling direction (the forward direction of the vehicle, the backward direction of the vehicle), etc. When a drawing shows that multiple elements (components, parts, etc.) are lined up in a predetermined direction, it may be assumed that the description in the specification contains a sentence explaining that they overlap when viewed in the predetermined direction.

[0013] "Not overlapping when viewed in a predetermined direction" and "offset when viewed in a predetermined direction" mean that multiple elements are not lined up in a predetermined direction, and are synonymous with "not overlapping in a predetermined direction" and "offset in a predetermined direction." Examples of the "predetermined direction" include the axial direction, radial direction, gravity direction, and vehicle travel direction (vehicle forward direction, vehicle backward direction). When a drawing shows that multiple elements (components, parts, etc.) are not lined up in a predetermined direction, it may be assumed that the description in the specification includes a sentence explaining that they are not overlapping when viewed in a predetermined direction.

[0014] The phrase "element A (component, part, etc.) is located between element B (component, part, etc.) and element C (component, part, etc.) when viewed from a predetermined direction" means that element A can be observed to be located between element B and element C when viewed from a predetermined direction. The "predetermined direction" is, for example, the axial direction, the radial direction, the direction of gravity, the vehicle traveling direction (the forward direction of the vehicle, the backward direction of the vehicle), etc. For example, when element B, element A, and element C are lined up in this order along the axial direction, it can be said that element A is located between element B and element C when viewed from a radial direction. When a drawing shows that element A is located between element B and element C when viewed from a predetermined direction, it can be considered that the description in the specification includes a sentence explaining that element A is located between element B and element C when viewed from the predetermined direction.

[0015] "Axial direction" refers to the axial direction of the rotation axis of a component constituting the drive device. "Radial direction" refers to the direction perpendicular to the rotation axis of a component constituting the drive device. The component may be, for example, a motor, a gear mechanism, a differential gear mechanism, etc.

[0016] The present embodiment will be described below. In the present embodiment, a drive device 1 mounted on a vehicle V will be described as an example. Fig. 1 is a schematic diagram illustrating the arrangement of the drive device 1 in the vehicle V. Fig. 2 is a schematic diagram illustrating the general configuration of the drive device 1.

[0017] Here, the "up-down direction" in the drawings means the vertical direction when the state in which the drive unit 1 is mounted on the vehicle V is used as a reference. Therefore, when written as "upper side," it means "upper side" in the vertical direction, and when written as "lower side," it means "lower side" in the vertical direction. Furthermore, the "front-rear direction" means the front-rear direction of the vehicle when the state in which the drive unit 1 is mounted on the vehicle V is used as a reference. Therefore, when written as "front side," it means "front side" in the front-rear direction of the vehicle, and when written as "rear side," it means "rear side" in the front-rear direction of the vehicle.

[0018] As shown in Figure 1, the drive unit 1 is mounted on the rear side of the vehicle V. A battery BT is provided in front of the drive unit 1. The drive unit 1 is disposed between frames FR, FR that are spaced apart in the front-to-rear direction. The frames FR, FR are oriented along the vehicle width direction.

[0019] 1 and 2, the drive unit 1 includes a motor 2 as a drive source, a power transmission mechanism 3 that transmits the rotation of the motor 2 to left and right drive wheels WH, WH, and an inverter INV that converts the power of a battery BT and supplies current to the motor 2. The drive unit 1 also includes a housing HS that accommodates the motor 2, the power transmission mechanism 3, and the inverter INV.

[0020] The housing HS has a motor case 10 (motor housing) that houses the motor 2, a gear case 12 (power transmission mechanism housing) that houses the power transmission mechanism 3, and an inverter case 14 (inverter housing) that houses the inverter INV. The gear case 12 is provided adjacent to the motor case 10 from the left side in the vehicle width direction (the lower side in FIG. 1 ). The inverter case 14 is provided in a position that overlaps with the motor case 10 when viewed from above.

[0021] 2, in the drive unit 1, the rotational driving force of the motor 2 is transmitted to a power transmission mechanism 3. The power transmission mechanism 3 has an input shaft 4 that rotates integrally with the motor 2, an intermediate shaft 5 that reduces the rotation of the input shaft 4 and transmits it to a differential mechanism 6, and drive shafts 7 (7A, 7B) that transmit the rotation of the differential mechanism 6 to the left and right drive wheels WH, WH.

[0022] The input shaft 4 has a shaft portion 40 that is provided coaxially with the motor shaft 20 of the motor 2, and a gear portion 41 that is formed on the outer periphery of the shaft portion 40. The shaft portion 40 is spline-fitted with the motor shaft 20, and rotates integrally with the motor shaft 20 around the rotation axis X1.

[0023] The intermediate shaft 5 has a shaft portion 50 that extends along a rotation axis X2 that is parallel to the rotation axis X1, and two gear portions (a large-diameter gear portion 51 and a small-diameter gear portion 52) that have different diameters and are provided on the outer periphery of the shaft portion 50. The large-diameter gear portion 51 and the small-diameter gear portion 52 rotate integrally with the shaft portion 50 around the rotation axis X2.

[0024] The gear portion 41 of the input shaft 4 meshes with the large diameter gear portion 51 of the intermediate shaft 5. The small diameter gear portion 52 of the intermediate shaft 5 meshes with the final gear 61 of the differential mechanism 6.

[0025] The final gear 61 is fixed to the outer periphery of the differential case 60 and rotates integrally with the differential case 60 around a rotation axis X3. The rotation axis X3 is parallel to the rotation axes X1 and X2. The differential case 60 is connected to the drive shafts 7 (7A, 7B) via bevel gears 62 and side gears 63. Therefore, the drive shafts 7 (7A, 7B) rotate together with the final gear 61 around the rotation axis X3. In other words, the differential mechanism 6 and the drive shafts 7 (7A, 7B) form the output shaft 8 of the drive unit 1.

[0026] In the drive unit 1, the rotation axis X1 of the motor shaft 20 and the input shaft 4, the rotation axis X2 of the intermediate shaft 5, and the rotation axis X3 of the output shaft 8 are arranged in this order from the rear to the front in the fore-and-aft direction.

[0027] 2, these rotation axes X1 to X3 are oriented along the vehicle width direction. Note that, hereinafter, these rotation axes X1 to X3 may also be collectively referred to as rotation axis X as necessary.

[0028] The motor case 10 has an inner case 18 surrounding the rotation axis X1, an outer case 11 fitted onto the inner case 18, and a cover member 13 joined to the outer case 11 from the direction of the rotation axis X1.

[0029] The inner case 18 has a cylindrical support wall portion 181, a flange-shaped joint portion 182 provided at the other end 181b of the support wall portion 181, and grooves 185 and wall portions 186 provided on the outer periphery of the support wall portion 181. The grooves 185 and the wall portions 186 are provided alternately in the direction of the rotation axis X1.

[0030] The support wall portion 181 is provided in a direction along the rotation axis X1 of the motor 2. The motor 2 is housed inside the support wall portion 181. When viewed from the radial direction of the rotation axis X1, the recessed groove 185 and the wall portion 186 overlap with the motor 2.

[0031] The outer case 11 has a cylindrical peripheral wall 111 that is fitted onto the support wall 181 of the inner case 18. The inner case 18 and the outer case 11 are assembled together by fitting the peripheral wall 111 of the outer case 11 onto the support wall 181 of the inner case 18. The inner case 18 is positioned so that the joint 182 abuts against the other end 111b of the peripheral wall 111 of the outer case 11 from the direction of the rotation axis X1. In this state, the inner case 18 is connected to the outer case 11 with bolts (not shown).

[0032] As a result, the opening of the recessed groove 185 is closed by the peripheral wall 111, and a cooling path CP2 (second cooling path) is formed between the support wall 181 and the peripheral wall 111. A refrigerant such as a liquid (cooling water, etc.) or a gas (air, etc.) flows through the cooling path CP2. In this embodiment, a case where cooling water W is used as the refrigerant will be described as an example. The cooling water W flowing through the cooling path CP2 cools the motor 2.

[0033] The cover member 13 is connected to the other end 111b of the peripheral wall portion 111 of the outer case 11 with a bolt B (see FIG. 3). In this state, the joint portion 182 of the inner case 18 is housed inside the cover member 13. Therefore, the inner case 18 is not exposed to the outside of the motor case 10.

[0034] A wall portion 112 is provided on one end 111a of the peripheral wall portion 111 of the outer case 11, extending radially inward between the motor 2 and the power transmission mechanism 3. The wall portion 112 is oriented perpendicular to the rotation axis X1.

[0035] The space formed inside the motor case 10 and the gear case 12 is divided into two by a wall 112. The space on the motor 2 side from the wall 112 (on the right side in the figure) is a motor chamber Sa that houses the motor 2. The space on the power transmission mechanism 3 side from the wall 112 (on the left side in the figure) is a gear chamber Sb that houses the power transmission mechanism 3.

[0036] A cylindrical wall portion 113 surrounding the rotation axis X1 is provided in a region of the wall portion 112 that intersects with the rotation axis X1. A bearing Bm is provided on the inner periphery of the cylindrical wall portion 113 on the motor chamber Sa side. The motor shaft 20 is supported by the cylindrical wall portion 113 via the bearing Bm. A bearing B4 is provided on the inner periphery of the cylindrical wall portion 113 on the gear chamber Sb side. The shaft portion 40 of the input shaft 4 is supported by the cylindrical wall portion 113 via the bearing B4.

[0037] A cylindrical wall portion 114 is provided on the surface of the wall portion 112 facing the power transmission mechanism 3 (left side in the figure), forward of the rotation axis X1. The cylindrical wall portion 114 has a cylindrical shape that surrounds the rotation axis X2. A bearing B5 is provided on the inner periphery of the cylindrical wall portion 114. The bearing B5 supports the shaft portion 50 of the intermediate shaft 5.

[0038] The outer case 11 has a bulging wall portion 15 on the side surface on the front side of the vehicle (upper side in the figure) that bulges forward from the peripheral wall portion 111. The bulging wall portion 15 is formed by enlarging a portion of the outer case 11 in order to accommodate the differential mechanism 6, which is located on the front side of the vehicle when viewed from the motor 2.

[0039] Furthermore, in the outer case 11, a cooling path CP1 (first cooling path), which will be described later, is provided at the connection between the bulging wall portion 15 and the peripheral wall portion 111. The cooling path CP1 is provided between the motor 2 and the output shaft 8 in the front-to-rear direction. As will be described in detail later, the cooling path CP1 communicates with a cooling path CP2 that cools the motor 2. A portion of the cooling water W flowing through the cooling path CP2 flows into the cooling path CP1 and then returns to the cooling path CP2. The cooling path CP1 is attached to the inverter case 14, which will be described later, and is provided to cool the inverter INV (see FIG. 1) inside the inverter case 14 by the cooling water W flowing through the cooling path CP1.

[0040] The bulging wall portion 15 has wall portions 151 and 152. The wall portions 151 and 152 extend from the outer periphery of the peripheral wall portion 111 toward the front of the vehicle. The wall portions 151 and 152 are each provided in a direction perpendicular to the rotation axis X3. The wall portions 151 and 152 are provided at an interval in the direction of the rotation axis X3. When viewed from the front of the vehicle, the wall portions 151 and 152 are provided in positions overlapping with the motor 2. The wall portion 152 is located closer to the cover member 13 than the wall portion 151.

[0041] The drive shaft 7A passes through the region of the wall 152 where the rotation axis X3 intersects with the wall 152. The wall 152 is provided with a cylindrical drive shaft support portion 152a that surrounds the drive shaft 7A.

[0042] A bearing B7 is supported on the inner periphery of the drive shaft support portion 152a. The drive shaft 7A is supported by the drive shaft support portion 152a via the bearing B7.

[0043] A cylindrical differential case support portion 151a is provided in a region where the wall portion 151 intersects with the rotation axis X3. A support cylinder 601 of the differential case 60 penetrates the differential case support portion 151a in the direction of the rotation axis X3.

[0044] A bearing B6 is supported on the inner periphery of the differential case support portion 151a. The support cylinder 601 of the differential case 60 is supported by the differential case support portion 151a via the bearing B6.

[0045] As shown in Fig. 4, the bulging wall portion 15 has a connecting wall 153 extending in the up-down direction on the front side of the vehicle. As shown in Fig. 2, the connecting wall 153 is provided in a direction along the rotation axis X3 (direction along the left-right direction in the figure). The front ends of the wall portions 151 and 152 are connected to the surface of the connecting wall 153 facing the motor 2 (the lower surface in the figure).

[0046] The connecting wall 153 is formed to have a range in the direction of the rotation axis X3 that extends from the front side of the differential case 60 to the front side of the motor 2. On the motor 2 side of the connecting wall 153 (the lower side in the figure), the differential case 60, the wall portion 151, and the wall portion 152 are lined up in this order in the direction of the rotation axis X3.

[0047] One end 153a and the other end 153b of the connecting wall 153 in the direction of the rotation axis X3 are flush with one end 111a and the other end 111b of the peripheral wall portion 111. The gear case 12 is connected to one end 153a of the connecting wall 153 with a bolt B (see FIG. 5).

[0048] The gear case 12 has a bottom wall portion 120 that is provided in a direction perpendicular to the rotation axes X1 to X3, and a peripheral wall portion 121 that completely surrounds the outer periphery of the bottom wall portion 120. A tip end surface 121a of the peripheral wall portion 121 has a rear region (lower region in FIG. 2 ) in the vehicle longitudinal direction joined to one end 111a of the peripheral wall portion 111, and a front region (upper region in FIG. 2 ) joined to one end 153a of the connecting wall 153 of the bulging wall portion 15.

[0049] A bearing B4 is provided in a region of the bottom wall portion 120 where the rotation axis X1 intersects. The bearing B4 supports the shaft portion 40 of the input shaft 4. As a result, both ends of the input shaft 4 in the direction of the rotation axis X1 are supported by the motor case 10 side and the gear case 12 side, and the input shaft 4 is provided rotatable about the rotation axis X1.

[0050] A bearing B5 is provided in a region of the bottom wall portion 120 where the rotation axis X2 intersects with the bearing B5. The bearing B5 supports the shaft portion 50 of the intermediate shaft 5. As a result, both ends of the intermediate shaft 5 in the direction of the rotation axis X2 are supported by the motor case 10 side and the gear case 12 side, and the intermediate shaft 5 is provided rotatable about the rotation axis X2.

[0051] A cylindrical differential case support portion 122 is provided in the bottom wall portion 120 in an area where the rotation axis X3 intersects with the differential case 60. The support cylinder 602 of the differential case 60 penetrates the cylindrical differential case support portion 122 in the direction of the rotation axis X3. A bearing B6 is supported on the inner periphery of the differential case support portion 122. The support cylinder 602 of the differential case 60 is supported by the differential case support portion 122 via the bearing B6. As a result, both ends of the differential case 60 in the direction of the rotation axis X3 are supported by the motor case 10 side and the gear case 12 side, and the differential case 60 is rotatable about the rotation axis X3.

[0052] Drive shafts 7A and 7B are inserted through the inner peripheries of support cylinders 601 and 602 of the differential case 60. The rotation of the differential case 60 is transmitted to the drive shafts 7A and 7B via a bevel gear 62 and a side gear 63. Therefore, in conjunction with the rotation of the differential case 60, the drive shafts 7A and 7B also rotate around the rotation axis X3.

[0053] The cover member 13 has a wall portion 130 perpendicular to the rotation axis X1 and a peripheral wall portion 131 surrounding the outer periphery of the wall portion 130. One end 131a of the peripheral wall portion 131 is joined to the other end 111b of the peripheral wall portion 111 of the outer case 11 from the direction of the rotation axis X1. The peripheral wall portion 131 is joined to the peripheral wall portion 111 of the outer case 11 on the outer diameter side of the joint portion 182 of the inner case 18. As a result, the opening on the other end 111b side of the outer case 11 and the opening on the other end 181b side of the inner case 18 are closed by the cover member 13.

[0054] The cover member 13 has a motor support portion 135 provided on the surface of the wall portion 130 facing the motor chamber Sa. The motor support portion 135 is cylindrical and surrounds the rotation axis X1 with a gap therebetween. A bearing Bm 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 Bm.

[0055] The motor 2 has a motor shaft 20, a cylindrical rotor 21 fitted onto the motor shaft 20, and a stator 22 that surrounds the outer periphery of the rotor 21 with a gap between them. Bearings Bm, Bm are fitted onto the motor shaft 20 on one side and the other side of the rotor 21 in the direction of the rotation axis X1. The motor shaft 20 is rotatably supported by the motor case 10 via the bearings Bm, Bm. The stator 22 is inserted into the inner periphery of the support wall portion 181 of the inner case 18.

[0056] A wiring La extending from the inverter INV (see FIG. 1) is connected to the stator 22 of the motor 2. As shown in FIG. 1, a power supply line Lb extending from the battery BT is connected to the inverter INV. As a result, the power of the battery BT is converted by the inverter INV and supplied to the stator 22.

[0057] When power is supplied to the stator 22, a magnetic field is generated around the stator 22. This causes the rotor 21 and the motor shaft 20 to rotate around the rotation axis X1, thereby driving the motor 2.

[0058] When power is supplied from the battery BT to drive the motor 2, the stator 22 and the inverter INV generate heat. In this embodiment, the inverter INV and the stator 22 of the motor 2 are cooled by cooling paths CP1 and CP2 provided in the housing HS, respectively.

[0059] Fig. 3 is a diagram illustrating the cooling path CP2. Fig. 3 is a diagram illustrating the drive unit 1 as viewed from the rear. In Fig. 3, the outer case 11 is partially cut away to expose the inner case 18. Fig. 4 is a diagram illustrating the cooling path CP2. Fig. 4 is a schematic diagram of the A-A cross section of Fig. 3.

[0060] 3, in the housing HS, a groove 185 is provided on the outer periphery of the support wall portion 181 of the inner case 18. The groove 185 is provided over the entire circumference of the support wall portion 181 in the circumferential direction around the rotation axis X1.

[0061] The grooves 185 are arranged with a phase difference in the circumferential direction around the rotation axis X1, and are arranged in a spiral shape with their positions in the direction of the rotation axis X1 changing from the cover member 13 side toward the gear case 12 side.

[0062] Adjacent grooves 185, 185 in the direction of the rotation axis X1 are separated by a wall portion 186. The wall portions 186 are provided with a phase difference in the circumferential direction around the rotation axis X1, and are continuous spiral walls whose position in the direction of the rotation axis X1 changes from the cover member 13 side toward the gear case 12 side. The wall portions 186 have the same outer diameter as the outer periphery of the support wall portion 181.

[0063] 2, when the peripheral wall 111 of the outer case 11 is fitted onto the support wall 181 of the inner case 18, the inner periphery of the peripheral wall 111 of the outer case 11 abuts against the outer periphery of the support wall 181 of the inner case 18 and the outer periphery of the wall 186. As a result, the opening of the recessed groove 185 is closed by the peripheral wall 111, and a spiral cooling path CP2 surrounding the motor 2 is formed between the support wall 181 and the peripheral wall 111.

[0064] As shown in FIG. 3 , two pipes Pa and Pb are connected to the cooling path CP2. The pipe Pa penetrates the peripheral wall 111 of the outer case 11 from an upper portion on the cover member 13 side in the direction of the rotation axis X1. The pipe Pb penetrates the peripheral wall 111 of the outer case 11 from an upper portion on the gear case 12 side in the direction of the rotation axis X1. As shown in FIG. 4 , the pipe Pa is provided on a vertical line VL1 passing through the rotation axis X1. Note that the positions of the pipes Pa and Pb in the up-down direction are not limited to those shown in FIGS. 3 and 4 . For example, the pipe Pa may be provided above a horizontal line HL1 (see FIG. 4 ) passing through the rotation axis X1, and the pipe Pb may be provided below the horizontal line HL1 (see FIG. 4 ).

[0065] As shown in Fig. 3, the end of the pipe Pa opposite the cooling path CP2 is connected to the water pump WP. The end of the pipe Pb opposite the cooling path CP2 is connected to the radiator Rd. The radiator Rd and the water pump WP are connected by piping (not shown). This allows the coolant W to circulate among the cooling path CP2, the radiator Rd, and the water pump WP.

[0066] As shown in Fig. 4, a partition wall 187 that closes the cooling path CP2 is provided on the front side of the pipe Pa. The partition wall 187 is provided on the front side of the pipe Pa so as to cross the recessed groove 185 in the direction of the rotation axis X1 (see Fig. 17). As a result, the flow of the cooling water W supplied from the pipe Pa to the cooling path CP2 toward the partition wall 187 is blocked, and the flow is restricted to flow only in the clockwise direction in Fig. 4 when viewed from the direction of the rotation axis X1.

[0067] 3, the coolant W pumped by the water pump WP is supplied to the cooling path CP2 through the pipe Pa. The coolant W in the cooling path CP2 moves in a spiral pattern from the cover member 13 side to the gear case 12 side. The coolant W that has moved to the gear case 12 side is discharged from the pipe Pb, cooled by the radiator Rd, and then supplied again from the water pump WP through the pipe Pa to the cooling path CP2.

[0068] FIG. 5 is a diagram illustrating the bulging wall portion 15. FIG. 5 is a schematic diagram of the drive device 1 as viewed from the direction of the arrow A-A in FIG. 4. FIGS. 6 to 9 are diagrams illustrating the inverter case 14. FIG. 6 schematically illustrates the drive device 1 as viewed from the direction of the arrow A-A in FIG. 5. Note that FIG. 6 does not illustrate the lid portion 19 that covers the opening of the inverter case 14. Furthermore, in FIG. 6, to make it easier to understand the position of the mating surface between the outer case 11 and the lid portion 19 of the cover member 13, the mating surface area is indicated by hatching with different pitches. Also, in FIG. 6, the wall area that constitutes the cooling path CP1 is indicated by cross-hatching. Also, in FIG. 6, the cooling plate PT covering the area of ​​the cooling path CP1 is partially cut out to expose a portion of the cooling path CP1 located on the back side of the cooling plate PT. FIG. 7 schematically illustrates the drive device 1 as viewed from the direction of the arrow B-B in FIG. 5. Fig. 8 shows a schematic cross section of the drive device 1 taken along line A-A in Fig. 6. Fig. 9 shows a schematic cross section of the drive device 1 taken along line B-B in Fig. 6. Fig. 10 is a diagram illustrating the cooling path CP1. Fig. 10 shows a schematic cross section of the drive device 1 taken along line A-A in Fig. 7.

[0069] As shown in FIG. 5, the connecting wall 153 of the bulging wall portion 15 is provided in a range that crosses the drive shaft 7A in the vertical direction when viewed from the front-rear direction.

[0070] 4 , in the bulging wall portion 15, the connecting wall 153 and the peripheral wall portion 111 are provided with a gap in the front-to-rear direction. A wall portion 154 is provided above the connecting wall 153 and the peripheral wall portion 111. The wall portion 154 is provided across the connecting wall 153 and the peripheral wall portion 111. The wall portion 154 is located above the connecting wall 153 and the peripheral wall portion 111 and below a horizontal line HL2 that passes through the upper end 22T of the stator 22 of the motor 2.

[0071] Below the wall 154, a space Sd is formed, surrounded by the wall 154, the connecting wall 153, and the peripheral wall 111. This space Sd opens to the lower part of the housing HS. When viewed from the direction of the rotation axis X, the drive shaft 7A is provided within the space Sd. The wall 154 separates the space Sd, in which the drive shaft 7A is provided, from an internal space Sc of the inverter case 14, which will be described later. In other words, the wall 154 forms the bottom of the inverter case 14.

[0072] 10, one end 154a of the wall portion 154 in the direction of the rotation axis X3 abuts against the gear case 12. The other end 154b of the wall portion 154 abuts against a support wall portion 17 of the cover member 13, which will be described later.

[0073] As shown in Fig. 4, an inverter case 14 that houses an inverter INV is provided above the wall portion 154 of the bulging wall portion 15. As shown in Fig. 6, the inverter case 14 is provided at a position offset forward from the rotation axis X1 of the motor 2 when viewed from above. In this state, the inverter case 14 is provided in a positional relationship that overlaps with the rotation axis X2 of the intermediate shaft 5 and the rotation axis X3 of the output shaft 8.

[0074] 5 , when viewed from the front side of the vehicle, the inverter case 14 has a range in the direction of the rotation axis X3 that straddles the outer case 11 and the cover member 13. The inverter case 14 is provided at a position offset from the gear case 12 in the direction of the rotation axis X3. Therefore, when viewed from above, the inverter case 14 is provided in a positional relationship in which it overlaps with the outer case 11 and the cover member 13, but is provided in a positional relationship in which it does not overlap with the gear case 12.

[0075] 8 , inverter case 14 has a support wall 16 on the outer case 11 side, a support wall 17 on the cover member 13 side, and a lid 19. Inverter case 14 is formed by joining support wall 16 on the outer case 11 side and support wall 17 on the cover member 13 side together to form an opening, which is closed by lid 19 provided across support wall 16 and support wall 17.

[0076] As shown in Fig. 4, the support wall portion 16 protrudes upward from the wall portion 154 of the bulging wall portion 15 and the peripheral wall portion 111. As shown in Fig. 6, when viewed from above, the support wall portion 16 is a continuous wall made up of a first wall portion 161 extending along the front-rear direction, and a second wall portion 162 and a third wall portion 163 extending along the direction of the rotation axis X.

[0077] The first wall portion 161 is disposed in a position offset from the cover member 13 toward the gear case 12 (to the right in the figure) and oriented along the front-to-rear direction (up-and-down direction in the figure). The first wall portion 161 is provided in a range that crosses the area overlapping with the bulging wall portion 15 in the front-to-rear direction of the vehicle. The rear end of the first wall portion 161 reaches between the rotation axis X1 and the rotation axis X2. The second wall portion 162 extends from the front end of the first wall portion 161 toward the cover member 13 in the direction of the rotation axis X. The third wall portion 163 extends from the rear end of the first wall portion 161 toward the cover member 13 in the direction of the rotation axis X. As shown in FIG. 4 , the third wall portion 163 protrudes upward from the peripheral wall portion 111 at a position offset forward of the vertical line VL1 when viewed in the direction of the rotation axis X.

[0078] As shown in Fig. 8, the tip surface 163a of the third wall portion 163 in the direction of the rotation axis X is flush with the other end 111b of the peripheral wall portion 111. As shown in Fig. 9, the tip surface 163a of the third wall portion 163 in the direction of the rotation axis X is also flush with the other end 154b of the wall portion 154 of the bulging wall portion 15.

[0079] 6 , a tip surface 162a of the second wall portion 162 in the direction of the rotation axis X is flush with a tip surface 163a of the third wall portion 163. Therefore, the tip surface 162a of the second wall portion 162, the tip surface 163a of the third wall portion 163, the other end 111b of the peripheral wall portion 111 (see FIG. 8 ), and the other end 154b of the wall portion 154 of the bulging wall portion 15 (see FIG. 9 ) are located on the same plane along the mating surfaces of the outer case 11 and the cover member 13.

[0080] 7 , when viewed from the direction of the rotation axis X, the cover member 13 has a support wall portion 17 that bulges forward from the area of ​​the peripheral wall portion 131. Specifically, the support wall portion 17 is provided in an area forward of a vertical line VL1 passing through the rotation axis X1 and above a horizontal line HL1 passing through the rotation axis X1. When viewed from the direction of the rotation axis X, the support wall portion 17 is provided in a position that overlaps with the support wall portion 16 of the outer case 11 but does not overlap with the drive shaft 7A (a position offset upward from the drive shaft 7A).

[0081] 6, the cover member 13 has an extending wall portion 132 that extends forward from a peripheral wall portion 131. When viewed from above, the extending wall portion 132 overlaps with the rotation axis X3.

[0082] When viewed from above in the vertical direction, the support wall portion 17 is a continuous wall composed of a first wall portion 171 and a second wall portion 172 and a third wall portion 173 that extend along the rotation axis X. The first wall portion 171 is offset from the case member 11 toward the opposite side of the gear case 12 (left side in the figure) and is disposed along the front-rear direction (up-down direction in the figure). The first wall portion 171 extends in the front-rear direction along the side edge of the extending wall portion 132. The rear end of the first wall portion 171 reaches between the rotation axis X1 and the rotation axis X2. The second wall portion 172 extends from the front end of the first wall portion 171 toward the outer case 11. The third wall portion 173 extends from the rear end of the first wall portion 171 toward the outer case 11.

[0083] As shown in Fig. 8, a tip surface 173a of the third wall portion 173 on the outer case 11 side (right side in the figure) is provided flush with one end 131a of the peripheral wall portion 131. As shown in Fig. 9, the tip surface 173a of the third wall portion 173 in the direction of the rotation axis X is provided flush with one end 132a of the extending wall portion 132.

[0084] 6 , the tip surface 172a of the second wall portion 172 on the outer case 11 side (the right side in the figure) and the tip surface 173a of the third wall portion 173 are aligned in the direction of the rotation axis X. The tip surfaces 172a and 173a are flush with each other. Therefore, the tip surface 172a of the second wall portion 172, the tip surface 173a of the third wall portion 173, one end 131a of the peripheral wall portion 131 (see FIG. 8 ), and one end 132a of the extending wall portion 132 (see FIG. 9 ) are located on the same plane along the mating surfaces between the outer case 11 and the cover member 13.

[0085] When the outer case 11 and the cover member 13 are joined in the direction of the rotation axis X, a tip surface 162a of the second wall portion 162 of the support wall portion 16 abuts against a tip surface 172a of the second wall portion 172 of the support wall portion 17. A tip surface 163a of the third wall portion 163 of the support wall portion 16 abuts against a tip surface 173a of the third wall portion 173 of the support wall portion 17. As shown in Figure 8, the other end 111b of the peripheral wall portion 111 abuts against one end 131a of the peripheral wall portion 131. As shown in Figure 9, the other end 154b of the wall portion 154 of the bulging wall portion 15 abuts against one end 132a of the extending wall portion 132.

[0086] As a result, the space surrounded by the support wall portion 16, wall portion 154, and peripheral wall portion 111 provided on the outer case 11 and the support wall portion 17, peripheral wall portion 131, and extending wall portion 132 provided on the cover member 13 constitutes the internal space Sc of the inverter case 14.

[0087] 8 and 9 , the upper end surface 16a of the support wall portion 16 and the upper end surface 17a of the support wall portion 17 are flush with each other. A joining surface 19a of the lid portion 19 is joined to the upper end surfaces 16a, 17a of the support walls 16, 17 without any gaps. Therefore, the opening of the internal space Sc surrounded by the support walls 16, 17 is closed by the lid portion 19. In this way, the inverter INV (see FIG. 6 ) is accommodated in the internal space Sc of the inverter case 14.

[0088] 4, the inverter case 14 is provided offset forward from a vertical line VL1 passing through the rotation axis X1 of the motor 2. This allows the wall portion 154, which is the bottom of the inverter case 14, to be located below the apex (upper end 22T) of the motor 2 (upper end 22T of the stator 22). This allows the vertical dimension of the housing HS to be smaller than if the inverter case 14 were located at a position overlapping the upper end 22T of the stator 22 when viewed from above, for example, which contributes to a more compact housing HS.

[0089] When the inverter case 14 is disposed offset forward from the vertical line VL1 in this manner, a dead space may be formed in the housing HS in the region between the inverter INV, the output shaft 8, and the motor 2 as viewed from the direction of the rotation axis X. In this embodiment, this dead space is effectively utilized to provide a cooling path CP1 for cooling the inverter INV (see FIGS. 18 and 19 ). This improves cooling efficiency without increasing the size of the housing HS.

[0090] The cooling path CP1 will be described in detail below. As shown in Fig. 6, the cooling path CP1 is provided in the wall 154, which is the bottom of the inverter case 14. As shown in Fig. 10, the cooling path CP1 is provided between a recess 9 formed by recessing the wall 154 downward and a cooling plate PT that closes the upper opening of the recess 9. The recess 9 is provided across the gear chamber Sb and the space Sd through which the drive shaft 7A passes in the direction of the rotation axis X. The cooling path CP1 is also provided in a region sandwiched between the output shaft 8 and the inverter INV in the vertical direction.

[0091] The cooling plate PT is fixed to the wall portion 154 by bolts B (see FIG. 6 ). In this state, the cooling plate PT is exposed to the interior space Sc of the inverter case 14. In the inverter case 14, the inverter INV is provided above the cooling plate PT in the vertical direction, and the cooling path CP1 is provided below it.

[0092] The cooling plate PT is made of a material with high thermal conductivity, such as copper or aluminum, which promotes heat exchange between the inverter INV and the cooling water W flowing through the cooling path CP1. The inverter INV and the cooling plate PT may be in contact with each other or may be spaced apart from each other.

[0093] 11 to 16 are diagrams illustrating the cooling path CP1. In FIG. 11, an enlarged view of region C in FIG. 6 is shown. The cooling plate PT is not shown in FIG. 11. In FIG. 12, a cross section of the region where the cooling path CP1 is provided, taken along line A-A in FIG. 11, is schematically shown as viewed obliquely from above. In FIG. 13, a cross section of the region where the cooling path CP1 is provided, taken along line B-B in FIG. 11, is schematically shown. In FIG. 14, a cross section of the region where the cooling path CP1 is provided, taken along line C-C in FIG. 11, is schematically shown. In FIG. 15, a cross section of the region where the cooling path CP1 is provided, taken along line A-A in FIG. 14, is schematically shown. In FIG. 16, a cross section of the region where the cooling path CP1 is provided, taken along line B-B in FIG. 14, is schematically shown.

[0094] 11 , the recess 9 has a generally rectangular shape in top view. The recess 9 has short sides 91 and 92 extending along the rotation axis X3, and long sides 93 and 94 connecting the ends of the short sides 91 and 92 to each other.

[0095] As shown in Figure 12, the short side portion 91 is a wall that protrudes upward from the outer periphery of the peripheral wall portion 111. The short side portion 92 and the long side portion 93 are walls that protrude upward from the outer periphery of the wall portion 154. The short side portion 92 and the long side portion 93 also protrude downward from the inner periphery of the wall portion 154. Therefore, the short side portion 92 and the long side portion 93 are provided across the wall portion 154 in the up-down direction. Although not shown, the long side portion 94 is also a wall that crosses the wall portion 154 in the up-down direction.

[0096] The recess 9 also has a bottom 90 (bottom wall) that closes the lower part of the opening surrounded by the short sides 91, 92 and the long sides 93, 94. The bottom 90 is provided across the lower end of the short side 92 and the lower ends of the long sides 93, 94 in the vertical direction. The bottom 90 is offset downward from the wall 154.

[0097] The rear end of the bottom 90 in the front-to-rear direction is connected to the peripheral wall 111 below the short side 91. Two communication holes Ha, Hb that communicate with the cooling passage CP2 are provided in the area of ​​the peripheral wall 111 that is exposed within the recess 9. The communication holes Ha, Hb are provided in the area between the short side 91 and the bottom 90 in the up-down direction. The communication holes Ha, Hb are provided at an interval in the direction of the rotation axis X3.

[0098] 11 , the short sides 91 and 92 are spaced apart in the front-to-rear direction. The short side 91 is located rearward and the short side 92 is located forward, with respect to the rotation axis X3. A partition 95 is provided on the short side 91 in the region between the communication holes Ha and Hb in the direction of the rotation axis X3.

[0099] The partition 95 extends from the short side 91 to the short side 92 along a straight line Lm that is perpendicular to the rotation axis X3. A tip surface 951 of the partition 95 in the direction of the straight line Lm is located forward of the rotation axis X3. A gap CL is formed between the tip surface 951 of the partition 95 and the short side 92.

[0100] As shown in Figure 12, the top surface 91a of the short side portion 91, the top surface 92a of the short side portion 92, the top surface 93a of the long side portion 93, the top surface 94a of the long side portion 94 (see Figure 13), and the top surface 95a of the partition portion 95 are located on the same plane in the vertical direction.

[0101] 13, when the upper opening of the recess 9 is closed with the cooling plate PT, the cooling plate PT comes into contact over the entire surface with the upper surfaces 91a, 92a of the short side portions 91, 92, the upper surfaces 93a, 94a of the long side portions 93, 94, and the upper surface 95a of the partition portion 95. As a result, the space within the recess 9 is divided into a space R1 on the long side 93 side and a space R2 on the long side 94 side, with the partition portion 95 sandwiched between them.

[0102] 11 , the spaces R1 and R2 communicate with the communication holes Ha and Hb, respectively, on the rear side. The spaces R1 and R2 also communicate with each other on the front side via the gap CL. Therefore, a single cooling path CP1 is formed within the recess 9, consisting of the communication hole Ha, the space R1, the gap CL, the space R2, and the communication hole Hb.

[0103] 14, the communication holes Ha and Hb are offset in position in the vertical direction. In the vertical direction, the communication hole Hb is located lower than the communication hole Ha by a height h. Therefore, as shown in FIG. 12, the portion of the bottom 90 that connects to the peripheral wall 111 on the communication hole Hb side has a shape that is recessed lower than the portion that connects to the peripheral wall 111 on the communication hole Ha side.

[0104] 15 , the bottom 90 has a first bottom wall portion 901 in a region that forms the space R1 of the recess 9. The first bottom wall portion 901 connects the peripheral wall portion 111 and the lower end of the short side portion 92 below the communication hole Ha. The first bottom wall portion 901 is provided along a straight line Ln1. The straight line Ln1 intersects with a vertical line VL3 that passes through the rotation axis X3, and is slightly inclined so that its height decreases from the rear side (the motor 2 side) to the front side (the output shaft 8 side).

[0105] As shown in FIG. 16 , the bottom 90 has a second bottom wall portion 902 in the region that defines the space R2 of the recess 9. The second bottom wall portion 902 is provided along a straight line Ln2. The straight line Ln2 intersects with a vertical line VL3 and is slightly inclined so that its height decreases from the front side (the output shaft 8 side) to the rear side (the motor 2 side). The front end of the second bottom wall portion 902 is connected to the front end of the first bottom wall portion 901 via a gap CL. The front end of the second bottom wall portion 902 is flush with the front end of the first bottom wall portion 901.

[0106] A third bottom wall portion 903 (step portion) extending downward between the output shaft 8 and the motor 2 is connected to the rear end of the second bottom wall portion 902. The third bottom wall portion 903 is inclined downwardly toward the motor 2. The third bottom wall portion 903 is provided in a range that crosses the communication hole Hb in the vertical direction.

[0107] A fourth bottom wall portion 904 (guide portion) is connected to the lower end of the third bottom wall portion 903. The fourth bottom wall portion 904 connects the lower end of the third bottom wall portion 903 to the region below the communication hole Hb in the peripheral wall portion 111. The fourth bottom wall portion 904 is slightly inclined so that its height decreases from the front side (the third bottom wall portion 903 side) to the rear side (the peripheral wall portion 111 side).

[0108] As shown in Figure 13, the long side portion 94 that forms the space R2 of the recess 9 has a wall portion 941 that joins with the cooling plate PT and a connecting wall portion 942 that connects the lower end of the wall portion 941 to the second bottom wall portion 902 of the bottom portion 90.

[0109] 14 , the connecting wall 942 is also connected to the fourth bottom wall 904 of the bottom 90 via a wall 943. The connecting wall 942 is oriented along a straight line Lp. The straight line Lp is inclined from the top to the bottom in a direction approaching the communication hole Hb.

[0110] 17 to 19 are diagrams illustrating the flow of cooling water W within the housing HS. FIG. 17 schematically shows a cross section of the recess 9 taken along line A-A in FIG. 15. In FIG. 17, the inner case 18 is shown in a plan view (developed view) to make it easier to understand the positional relationship between the cooling paths CP1 and CP2. FIG. 18 schematically shows a cross section taken along line A-A in FIG. 17. FIG. 19 schematically shows a cross section taken along line B-B in FIG. 17.

[0111] 17 , when the peripheral wall 111 of the outer case 11 is fitted onto the support wall 181 of the inner case 18, the opening of the recessed groove 185 of the inner case 18 is closed by the peripheral wall 111. As a result, a spiral cooling path CP2 surrounding the motor 2 is formed between the support wall 181 and the peripheral wall 111. As shown in FIGS. 18 and 19 , the cooling water W in the cooling path CP2 flows clockwise when viewed from the direction of the rotation axis X1.

[0112] 17 , cooling water W is supplied to the cooling path CP2 from the pipe Pa side. The cooling water W in the cooling path CP2 moves from the cover member 13 side (upper side in the figure) to the gear case 12 side (lower side in the figure) and is then discharged from the pipe Pb. That is, the cover member 13 side of the cooling path CP2 is the upstream side, and the gear case 12 side is the downstream side.

[0113] The recess 9 is provided in a region between the pipes Pa and Pb in the direction of the rotation axis X1. The partition 95 of the recess 9 is provided in a position overlapping with the wall 186 when viewed from the front-to-rear direction. Therefore, the communication holes Ha and Hb located on one side and the other side of the partition 95 in the direction of the rotation axis X1 communicate with the adjacent cooling paths CP2 and CP2 across the wall 186, respectively.

[0114] In the direction of the rotation axis X1, the communication hole Ha is located on the cover member 13 side (upstream side), and the communication hole Hb is located on the gear case 12 side (downstream side). Therefore, a portion of the cooling water W flows from the cooling path CP2 through the communication hole Ha into the cooling path CP1 in the recess 9. The bottom 90 of the recess 9 is inclined so as to become lower toward the first bottom wall portion 901 to the fourth bottom wall portion 904 (see FIGS. 15 and 16 ). Therefore, the cooling water W that flows into the cooling path CP1 travels from the first bottom wall portion 901 to the fourth bottom wall portion 904, and is finally discharged from the communication hole Hb to the cooling path CP2. In other words, the communication hole Ha constitutes the supply port of the cooling path CP1, and the communication hole Hb constitutes the discharge port of the cooling path CP1.

[0115] 18 , the communication hole Ha is provided in a region of the peripheral wall portion 111 that is above the horizontal line HL1 and forward of the vertical line VL1. As a result, as the cooling water W moving clockwise through the cooling path CP2 crosses the communication hole Ha from below to above, a portion of the cooling water W branches off and is taken into the cooling path CP1 from the communication hole Ha. The remaining cooling water W that is not taken into the cooling path CP1 moves clockwise through the cooling path CP2 to cool the motor 2.

[0116] When cooling water W flows into the cooling path CP1, the space R1 in the recess 9 is filled with the cooling water W. A cooling plate PT is provided above the recess 9. The cooling plate PT is cooled by the cooling water W in the space R1. The cooled cooling plate PT exchanges heat with the inverter INV, cooling the inverter INV.

[0117] 19 , the cooling water W in the space R1 passes through the gap CL between the partition 95 and the short side portion 92 and moves to the space R2 side of the recess 9. As a result, the space R2 is filled with the cooling water W. The cooling plate PT is cooled by the cooling water W in the space R2. The cooled cooling plate PT exchanges heat with the inverter INV, cooling the inverter INV.

[0118] In the recess 9, a tip end surface 951 of the partition portion 95 extends forward of the rotation axis X3. Therefore, the cooling water W that flows in from the communication hole Ha side moves to the front side of the rotation axis X3, then turns back at the tip end surface 951 of the partition portion 95 and flows toward the communication hole Hb. This allows the flow path length of the cooling passage CP1 to be longer, increasing the contact time between the cooling water W and the cooling plate PT and improving heat exchange efficiency.

[0119] Furthermore, when viewed from the partition 95, a first bottom wall portion 901, which is the area on the communication hole Ha side of the bottom 90 of the recess 9, slopes downward from the motor 2 side toward the output shaft 8 side. A second bottom wall portion 902 to a fourth bottom wall portion 904, which are the areas on the communication hole Hb side, slope downward from the output shaft 8 side toward the motor 2 side.

[0120] Here, the longer the flow path length of the cooling path CP1, the slower the flow velocity of the cooling water W flowing through the cooling path CP1. Therefore, by sloping the first bottom wall portion 901 to the fourth bottom wall portion 904 of the bottom 90, the cooling water W flows by its own weight along the slope. This allows the cooling water W to move without significantly reducing the flow velocity even in the cooling path CP1 having a long flow path length.

[0121] 13 and 14 , the long side portion 94 has a connecting wall portion 942 that slopes downward toward the communication hole Hb. The cooling water W that moves toward the space R2 of the recess 9 is guided by the connecting wall portion 942, making it easier to be discharged from the communication hole Hb. This makes it difficult for the cooling water W to stagnate in the cooling passage CP1.

[0122] 19 , the communication hole Hb is provided in a region of the peripheral wall portion 111 that is above the horizontal line HL1 and forward of the vertical line VL1. Therefore, the cooling water W moving clockwise through the cooling path CP2 crosses the communication hole Hb from bottom to top. At this time, the cooling water W in the cooling path CP1 that is discharged from the communication hole Hb merges with the cooling water W in the cooling path CP2. The merged cooling water W moves clockwise through the cooling path CP2 to cool the motor 2.

[0123] 14, the communication hole Hb is positioned lower than the communication hole Ha in the vertical direction, so that the cooling water W that flows into the cooling passage CP1 from the communication hole Ha can move toward the communication hole Hb by utilizing gravity.

[0124] For example, if the communication holes Ha and Hb are aligned in the vertical direction, or if the communication hole Hb is positioned higher than the communication hole Ha, gravity cannot be utilized, and the flow rate of the coolant W in the cooling path CP1 tends to be slower, which affects the cooling efficiency of the inverter case 14. Therefore, by displacing the communication hole Hb vertically below the communication hole Ha, gravity can be utilized to increase the flow rate of the coolant W in the cooling path CP1, thereby enabling efficient cooling of the inverter INV.

[0125] Furthermore, by providing the third bottom wall portion 903 and the fourth bottom wall portion 904, the cooling water W flowing along the second bottom wall portion 902 is accelerated by passing through the third bottom wall portion 903. The cooling water W accelerated by the third bottom wall portion 903 is guided by the fourth bottom wall portion 904 and discharged from the communication hole Hb while maintaining its flow velocity. This allows the cooling water W in the cooling path CP1 to be discharged more quickly.

[0126] It is also conceivable that the cooling water W in the cooling path CP2 may flow back toward the cooling path CP1 through the communication hole Hb. Therefore, by providing the third bottom wall portion 903 across the communication hole Hb in the vertical direction, even if the cooling water W on the cooling path CP2 side flows back from the communication hole Hb, it can be made to collide with the third bottom wall portion 903, thereby significantly reducing the momentum of the backflowing cooling water W. This makes it possible to reduce the backflow of the cooling water W from the communication hole Hb toward the communication hole Ha inside the cooling path CP1.

[0127] 10 , oil OL is stored in the gear chamber Sb to lubricate the meshing portions of the gears of the power transmission mechanism 3. For example, if the oil OL is stirred up by the rotation of the final gear 61 of the differential mechanism 6 and adheres to the wall portion 154, the heat of the oil OL may be transmitted to the inverter case 14 side via the wall portion 154.

[0128] 19 , in this embodiment, the cooling path CP1 is provided to cover the upper side of the output shaft 8 when viewed from the direction of the rotation axis X. As a result, the oil OL scooped up in the gear chamber Sb is cooled by the cooling path CP1. Therefore, the heat of the oil OL in the gear chamber Sb is not easily transferred to the inverter case 14. Because the scooped up oil OL is cooled by the cooling path CP1, the oil OL in the gear chamber Sb is also cooled.

[0129] In this manner, in this embodiment, by providing the cooling passage CP1 between the inverter case 14 and the output shaft 8 in the vertical direction, it is possible to cool both the inverter INV and the oil OL in the gear chamber Sb.

[0130] As described above, the vehicle drive device 1 of this embodiment has the following configuration: (1) The drive device 1 includes: a motor 2 that is a drive source for the vehicle V; an inverter INV that supplies current to the motor 2; a power transmission mechanism 3 that transmits power from the motor 2 to the drive wheels WH; and a housing HS that accommodates the motor 2, the inverter INV, and the power transmission mechanism 3. The housing HS includes: a motor case 10 (motor accommodating portion) that accommodates the motor 2; an inverter case 14 (inverter accommodating portion) that accommodates the inverter INV and is attached to the upper part of the motor case 10 in the vertical direction based on the installation state of the drive device 1 on the vehicle V; and a gear case 12 (power transmission mechanism accommodating portion) that accommodates the power transmission mechanism 3 and is disposed adjacent to the motor case 10 in the direction of the rotation axis X of the motor 2. The power transmission mechanism 3 has an output shaft 8 that outputs power from the motor 2. The rotation axis X3 of the output shaft 8 and the rotation axis X1 of the motor 2 are arranged parallel to each other with a gap in the fore-and-aft direction of the vehicle V. When viewed from above the vehicle V, the inverter case 14 is offset from the rotation axis X1 of the motor 2 and overlaps with the rotation axis X3 of the output shaft 8. When viewed from the direction of the rotation axis X1 of the motor 2, the wall portion 154 (bottom) of the inverter case 14 is located below a horizontal line HL2 that passes through the upper end 22T of the stator 22 of the motor 2 in the vertical direction. The inverter case 14 is provided with a cooling path CP1 (first cooling path) that cools the inverter INV. When viewed from the direction of the rotation axis X1 of the motor 2, the cooling path CP1 is provided between the inverter INV and the output shaft 8 in the vertical direction.

[0131] This configuration allows for a more vertically compact housing HS than, for example, locating the inverter case 14 at a position overlapping the apex of the motor 2 (the upper end 22T of the stator 22, see FIG. 4 ). With this arrangement, dead space may be formed in the housing HS between the inverter INV, the output shaft 8, and the motor 2 when viewed from the direction of the rotation axis X. Therefore, in this embodiment, this dead space is effectively utilized to provide a cooling path CP1 for cooling the inverter INV (see FIGS. 18 and 19 ). This improves cooling efficiency without increasing the size of the housing HS. Furthermore, oil OL for lubricating the meshing portions of the gears of the power transmission mechanism 3 is stored in the gear chamber Sb (see FIG. 10 ). When oil OL is stirred up by the rotation of the final gear 61 of the differential mechanism 6 and adheres to the wall 154, heat from the oil OL may be transferred to the inverter case 14 via the wall 154. Therefore, with the above configuration, the oil OL scooped up in the gear chamber Sb is cooled by the cooling path CP1. As a result, the heat of the oil OL is less likely to be transferred to the inverter case 14. Because the scooped up oil OL is cooled by the cooling path CP1, the oil OL in the gear chamber Sb is also cooled. In this way, by providing the cooling path CP1 between the inverter case 14 and the output shaft 8 in the vertical direction, it is possible to improve cooling efficiency, that is, to cool the inverter INV by the cooling path CP1 and to suppress heat transfer from the gear chamber Sb (gear case 12) side to the inverter case 14 side, while also achieving a compact housing HS.

[0132] (2) The motor case 10 is provided with a cooling path CP2 (second cooling path) that cools the motor 2. The cooling path CP1 is provided branching off from the cooling path CP2.

[0133] For example, if the cooling paths CP1 and CP2 were provided independently, separate piping or the like would be required to connect them. This would lead to an increase in the size of the drive unit 1. Therefore, by configuring as described above, the cooling paths CP1 and CP2 can share the cooling water W, resulting in a more efficient cooling path. This contributes to the miniaturization of the drive unit 1.

[0134] (3) The cooling passage CP1 has a communication hole Ha (supply port) through which the cooling water W (refrigerant) flows from the cooling passage CP2 and a communication hole Hb (discharge port) through which the cooling water W is discharged to the cooling passage CP2. The communication hole Hb is located below the communication hole Ha.

[0135] With this configuration, gravity can be utilized to promote the movement of the cooling water W in the cooling path CP1, thereby reducing the risk of the cooling water W stagnating in the cooling path CP1 and reducing the cooling efficiency.

[0136] (4) The cooling passage CP1 is provided in the recess 9 formed by recessing the wall portion 154 downward. The recess 9 has a partition portion 95 that separates the communication holes Ha and Hb. The partition portion 95 extends from the motor 2 side to the output shaft 8 side in the front-rear direction. The partition portion 95 has a gap CL that connects the space R1 on the communication hole Ha side of the recess 9 with the space R2 on the communication hole Hb side.

[0137] With this configuration, the cooling water W flowing in from the communication hole Ha side moves to the output shaft 8 side, then turns back at the gap CL and flows toward the communication hole Hb. This allows the flow path length of the cooling passage CP1 to be increased, increasing the cooling time by the cooling water W and improving heat exchange efficiency.

[0138] (5) When viewed from the partition 95, the first bottom wall 901 (the region of the bottom 90 (bottom wall) of the recess 9 on the side of the communication hole Ha) slopes downward from the motor 2 side toward the output shaft 8 side. The second bottom wall 902 (the region of the bottom 90 of the recess 9 on the side of the communication hole Hb) slopes downward from the output shaft 8 side toward the motor 2 side.

[0139] The longer the flow path length of the cooling path CP1, the slower the flow velocity of the cooling water W flowing through the cooling path CP1. Therefore, by configuring as described above, the cooling water W is made to flow along the slope by utilizing gravity. This allows the cooling water W to move without significantly reducing the flow velocity even in the cooling path CP1 having a long flow path length.

[0140] (6) The upper end of a third bottom wall portion 903 (step portion) is connected to the second bottom wall portion 902 on the motor 2 side in the front-rear direction. The third bottom wall portion 903 is provided in a range that crosses the communication hole Hb in the up-down direction. A fourth bottom wall portion 904 (guide portion) that extends toward the communication hole Hb is connected to the lower end of the third bottom wall portion 903.

[0141] With this configuration, the cooling water W flowing along the second bottom wall portion 902 is accelerated by gravity as it passes through the third bottom wall portion 903. The cooling water W accelerated by the third bottom wall portion 903 is guided by the fourth bottom wall portion 904 and discharged from the communication hole Hb while maintaining its flow velocity. This allows the cooling water W in the cooling path CP1 to be discharged more quickly. It is also possible that the cooling water W in the cooling path CP2, for example, may flow back toward the cooling path CP1 through the communication hole Hb. Therefore, with the above configuration, even if the cooling water W on the cooling path CP2 side flows back from the communication hole Hb, it collides with the third bottom wall portion 903, significantly reducing the momentum of the backflowing cooling water W. This reduces the backflow of the cooling water W from the communication hole Hb toward the communication hole Ha within the cooling path CP1.

[0142] Although the embodiments of the present invention have been described above, the present invention is not limited to the aspects shown in these embodiments and can be modified as appropriate within the scope of the technical concept of the invention.

[0143] 1: drive unit, 2: motor, 3: power transmission mechanism, 6: differential mechanism, 7, 7A, 7B: drive shaft, 8: output shaft, 9: recess, 10: motor case (motor housing section), 11: outer case, 12: gear case (power transmission mechanism housing section), 13: cover member, 14: inverter case (inverter housing section), 15: bulging wall section, 18: inner case, 22: stator, 22T: apex, 61: final gear, 90: bottom (bottom wall of recess), 95: partition section, 111: peripheral wall section, 154: wall section (bottom of inverter housing section), 181: support wall section, 185: recess, 18 6: wall portion, 901: first bottom wall portion (region on the supply port side of the bottom wall), 902: second bottom wall portion (region on the discharge port side of the bottom wall), 903: third bottom wall portion (step portion), 904: fourth bottom wall portion (guide portion), CL: gap, CP1: cooling path (first cooling path), CP2: cooling path (second cooling path), Ha: communication hole (supply port), Hb: communication hole (discharge port), HL1: horizontal line, HL2: horizontal line, HS: housing, INV: inverter, OL: oil, PT: cooling plate, R1: space, R2: space, V: vehicle, W: cooling water (refrigerant), WH: drive wheel, X, X1, X2, X3: rotating shaft

Claims

1. A drive unit comprising: a motor that is a drive source for a vehicle; an inverter that supplies current to the motor; a power transmission mechanism that transmits power from the motor to drive wheels; and a housing that accommodates the motor, the inverter, and the power transmission mechanism, wherein the housing has: a motor accommodating section that accommodates the motor; an inverter accommodating section that accommodates the inverter and is attached to an upper part of the motor accommodating section in a vertical direction based on the installation state of the drive unit on the vehicle; and a power transmission mechanism accommodating section that accommodates the power transmission mechanism and is disposed adjacent to the motor accommodating section in the direction of the rotational axis of the motor, the power transmission mechanism having an output shaft that outputs power from the motor, the rotational axis of the output shaft and the rotational axis of the motor being arranged parallel to each other with a gap in the fore-and-aft direction of the vehicle, and the inverter accommodating section being offset from the rotational axis of the motor and overlapping with the rotational axis of the output shaft when viewed from above the vehicle, A drive device, wherein, as viewed from the direction of the rotational axis of the motor, the bottom of the inverter accommodating section is located below a horizontal line passing through an upper end of the motor in the vertical direction, the inverter accommodating section is provided with a first cooling path for cooling the inverter, and as viewed from the direction of the rotational axis of the motor, the first cooling path is provided between the inverter and the output shaft in the vertical direction.

2. A drive device according to claim 1, wherein the motor housing is provided with a second cooling path for cooling the motor, and the first cooling path is provided branching off from the second cooling path.

3. A drive device according to claim 2, wherein the first cooling path has a supply port through which the refrigerant flows from the second cooling path and a discharge port through which the refrigerant is discharged into the second cooling path, and the discharge port is located below the supply port.

4. A drive device according to claim 3, wherein the first cooling passage is provided in a recess formed by recessing the bottom downward, the recess having a partition that separates the supply port and the discharge port, the partition extending from the motor side to the output shaft side in the front-to-rear direction, and the partition having a gap that connects the space on the supply port side of the recess with the space on the discharge port side.

5. A drive device according to claim 4, wherein, when viewed from the partition, the area of ​​the bottom wall of the recess on the supply port side is inclined downward from the motor side toward the output shaft side, and the area of ​​the bottom wall of the recess on the discharge port side is inclined downward from the output shaft side toward the motor side.

6. A drive device according to claim 5, wherein a step portion is provided on the motor side in the front-to-rear direction in the area of ​​the bottom wall of the recess on the side of the discharge outlet, the step portion is provided in a range that crosses the discharge outlet in the up-down direction, and a guide portion extending toward the discharge outlet is provided at the lower end of the step portion.

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