Vehicular drive device

Abstract

Disclosed herein is a vehicular drive device comprising: a rotary electric machine; a transmission mechanism that transmits a driving force from the rotary electric machine to wheels; a case which houses the rotary electric machine and the transmission mechanism and in which oil is accumulated in a lower portion thereof; and an oil cooler that is integrally formed with the case and exchanges heat between the oil and a cooling medium. The case has a first outer peripheral part that covers the radially outer side of the rotary electric machine, and a second outer peripheral part that covers the radially outer side of the transmission mechanism. The oil cooler is formed on one among the first outer peripheral part and the second outer peripheral part, and a heat exchange portion overlaps the other among the first outer peripheral part and the second outer peripheral part when viewed in the axial direction.

Description

Vehicle drive unit

[0001] The present disclosure relates to a vehicle drive device.

[0002] A technique is known in which an oil cooler is externally attached to the outside of a case that houses a rotating electrical machine.

[0003] Japanese Patent Application Laid-Open No. 2022-154181

[0004] However, in the conventional technology described above, when the vehicle drive system is viewed as a whole with the oil cooler attached, the projected area of ​​the entire vehicle drive system as viewed in the axial direction tends to be large due to the oil cooler, which may reduce the mountability of the vehicle.

[0005] Therefore, in one aspect, an object of the present disclosure is to reduce or eliminate the increase in the projected area of ​​the entire vehicle drive device as viewed in the axial direction, which is caused by the oil cooler.

[0006] In one aspect, a vehicle drive device is provided, comprising: a rotating electric machine; a transmission mechanism that transmits driving force from the rotating electric machine to wheels; a case that houses the rotating electric machine and the transmission mechanism and in which oil accumulates at the bottom; and an oil cooler that is integrally formed with the case and performs heat exchange between the oil and a cooling medium, wherein the case has a first outer circumferential portion that covers the radial outside of the rotating electric machine and a second outer circumferential portion that covers the radial outside of the transmission mechanism, and the oil cooler is formed on one of the first outer circumferential portion and the second outer circumferential portion, and when viewed in the axial direction, a heat exchange portion overlaps with the other of the first outer circumferential portion and the second outer circumferential portion.

[0007] According to one aspect of the present disclosure, it is possible to reduce or eliminate an increase in the projected area of ​​the entire vehicle drive device as viewed in the axial direction, which is caused by the oil cooler.

[0008] FIG. 1 is a schematic diagram of a top view showing a state in which a vehicle drive device is mounted in a vehicle. FIG. 2 is a skeleton diagram showing a vehicle drive device. FIG. 3 is a cross-sectional view showing a schematic configuration of a case of the vehicle drive device according to the present embodiment. FIG. 4 is a diagram showing a schematic example of a cooling system applicable to the present embodiment. FIG. 5 is a schematic explanatory diagram of a preferred arrangement example (part 1) of the oil cooler according to the present embodiment. FIG. 6 is a schematic explanatory diagram of a preferred arrangement example (part 2) of the oil cooler according to the present embodiment. FIG. 7 is a conceptual diagram of a preferred arrangement of the oil cooler. FIG. 8 is a perspective view (part 1) of a portion of the vehicle drive device including the oil cooler according to the first embodiment. FIG. 9 is a perspective view (part 2) of a portion of the vehicle drive device including the oil cooler according to the first embodiment. FIG. 10 is an explanatory view of the internal configuration of the oil cooler, which is a cross-sectional view taken at a specific position in the A direction. FIG. 11 is an explanatory view of the internal configuration of the oil cooler, which is a cross-sectional view taken at another specific position in the A direction. FIG. 12 is an explanatory view of the internal configuration of the oil cooler, which is a cross-sectional view taken at a still further specific position in the A direction. FIG. 1 is a diagram schematically showing the flow of oil and cooling water in the entire vehicle drive system when the oil cooler according to Example 1 is applied. FIG. 2 is a perspective view of a portion of the vehicle drive system equipped with the oil cooler according to Example 2. FIG. 3 is an exploded perspective view of a main body and a lid of the oil cooler according to Example 2. FIG. 4 is an explanatory view of the internal configuration of the oil cooler, a cross-sectional view at a specific A-direction position. FIG. 5 is an explanatory view of the internal configuration of the oil cooler, a cross-sectional view at another specific A-direction position. FIG. 6 is an explanatory view of the internal configuration of the oil cooler, a cross-sectional view at a still another specific A-direction position. FIG. 7 is a perspective view of the lid. FIG. 8 is a perspective view of a portion of the vehicle drive system equipped with the oil cooler according to Example 3. FIG. 9 is a perspective view of a portion of the vehicle drive system equipped with the oil cooler according to Example 4.

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not limiting. Furthermore, shapes and the like in the drawings may be partially exaggerated for the sake of explanation. Furthermore, in the drawings, for ease of viewing, reference symbols may be assigned only to some of the parts that exist with the same attribute.

[0010] In this specification, the term "driving connection" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force (synonymous with torque), and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members (e.g., shafts, gear mechanisms, belts, chains, etc.) that transmit rotation at the same speed or at variable speeds. Note that the transmission members may also include engagement devices (e.g., friction engagement devices, meshing engagement devices, etc.) that selectively transmit rotation and driving force.

[0011] In this specification, the term "rotating electric machine" is used as a concept that includes both a motor (electric motor), a generator (electric generator), and a motor-generator that functions as both a motor and a generator as needed. Furthermore, in this specification, with regard to the arrangement of two components, "overlapping when viewed in a specific direction" means that when an imaginary line parallel to the line of sight is moved in each direction perpendicular to the imaginary line, there is at least a region where the imaginary line intersects with both of the two components. Furthermore, in this specification, with regard to the arrangement of two components, "the arrangement regions in a specific direction overlap" means that the arrangement region of one component in a specific direction includes at least a portion of the arrangement region of the other component in a specific direction.

[0012] Fig. 1 is a schematic top view showing a state in which a vehicle drive device 100 is mounted in a vehicle VC. Fig. 2 is a skeleton diagram showing the vehicle drive device 100. Fig. 3 is a cross-sectional view showing a schematic configuration of a case 2 of the vehicle drive device 100 according to this embodiment. In Fig. 3, a case portion relating to an oil cooler 9, which will be described later, is not shown.

[0013] 1, the vehicle drive device 100 includes a rotating electric machine 1, a pair of output members 6 drivingly connected to a pair of wheels W (see FIG. 1), a transmission mechanism 3 that transmits driving force between the rotating electric machine 1 and the pair of output members 6, and an inverter device 4 that drives and controls the rotating electric machine 1. The vehicle drive device 100 further includes a case 2 that houses the rotating electric machine 1 and the inverter device 4. The case 2 also houses the pair of output members 6 and the transmission mechanism 3.

[0014] The first output member 61, which is one of the pair of output members 6, is drivingly connected to the first wheel W1, which is one of the pair of wheels W, and the second output member 62, which is the other of the pair of output members 6, is drivingly connected to the second wheel W2, which is the other of the pair of wheels W. As shown in FIG. 1 , the vehicle VC on which the vehicle drive device 100 is mounted includes a first drive shaft 63 that rotates integrally with the first wheel W1 and a second drive shaft 64 that rotates integrally with the second wheel W2. The first drive shaft 63 is connected to the first wheel W1 via, for example, a constant velocity joint, and the second drive shaft 64 is connected to the second wheel W2 via, for example, a constant velocity joint. The first output member 61 is connected to the first drive shaft 63 so as to rotate integrally therewith, and the second output member 62 is connected to the second drive shaft 64 so as to rotate integrally therewith.

[0015] The vehicle drive device 100 transmits the output torque of the rotating electric machine 1 to a pair of wheels W via a pair of output members 6, thereby propelling the vehicle VC on which the vehicle drive device 100 is mounted. In other words, the rotating electric machine 1 is a driving force source for the pair of wheels W. The pair of wheels W is a pair of left and right wheels of the vehicle VC (e.g., a pair of left and right front wheels or a pair of left and right rear wheels). The rotating electric machine 1 may be, for example, an AC rotating electric machine driven by three-phase AC (an example of polyphase AC). The rotating electric machine 1 is electrically connected to a battery (not shown) via an inverter device 4 that converts power between DC power and AC power. The rotating electric machine 1 receives power from the battery for power running, or supplies power generated by the inertial force of the vehicle VC to the battery for storage.

[0016] As shown in Fig. 2, the rotating electric machine 1 and the pair of output members 6 are arranged on two parallel axes (specifically, a first axis C1 and a second axis C2). Specifically, the rotating electric machine 1 is arranged on the first axis C1, and the pair of output members 6 are arranged on a second axis C2 different from the first axis C1. The first axis C1 and the second axis C2 are parallel axes (virtual axes). The transmission mechanism 3 includes an output gear (ring gear) 30 drivingly connected to at least one of the pair of output members 6, coaxially with the pair of output members 6 (i.e., on the second axis C2).

[0017] As shown in FIG. 1 , the vehicle drive device 100 is mounted on the vehicle VC with the axial direction A oriented along the vehicle transverse direction. The axial direction A is parallel to the first axis C1 and the second axis C2, in other words, a common axial direction between the first axis C1 and the second axis C2. That is, the axial direction A is the direction in which the rotational axis of the rotary electric machine 1 extends and also the direction in which the rotational axis of the pair of output members 6 extends. Here, one side of the axial direction A is referred to as the axial first side A1, and the other side of the axial direction A (the side opposite to the axial first side A1 in the axial direction A) is referred to as the axial second side A2. The axial first side A1 is the side in the axial direction A on which the rotary electric machine 1 is disposed relative to the transmission mechanism 3. As shown in FIG. 2 , the first output member 61 is the output member 6 disposed on the axial first side A1 of the pair of output members 6, and the second output member 62 is the output member 6 disposed on the axial second side A2 of the pair of output members 6.

[0018] As shown in FIG. 1 , the vehicle drive system 100 may be mounted on the vehicle VC with the first axial side A1 facing the right side of the vehicle and the second axial side A2 facing the left side of the vehicle. In this case, the first wheel W1 to which the first output member 61 is drivingly connected is the right wheel, and the second wheel W2 to which the second output member 62 is drivingly connected is the left wheel. In FIG. 1 , it is assumed that the vehicle drive system 100 is a front-wheel drive system that drives a pair of left and right front wheels. Therefore, in the example shown in FIG. 1 , the first wheel W1 is the right front wheel, and the second wheel W2 is the left front wheel.

[0019] The transmission mechanism 3 includes a speed reduction mechanism 34 in the power transmission path between the rotating electric machine 1 and the output gear 30. The speed reduction mechanism 34 is optional, and in this embodiment, as an example, it is a speed reduction mechanism that uses a counter gear on a third axis C3 that is parallel to the first axis C1 and the second axis C2. Note that in a modified example, the speed reduction mechanism 34 may be a speed reduction mechanism that uses a planetary gear on the first axis C1. In this case, the speed reduction mechanism may have a two-axis configuration.

[0020] The transmission mechanism 3 further includes a differential gear mechanism 5. The differential gear mechanism 5 distributes the driving force transmitted from the rotating electric machine 1 to the pair of output members 6. The differential gear mechanism 5 may be arranged coaxially with the pair of output members 6 (i.e., on the second axis C2). The differential gear mechanism 5 distributes the driving force transmitted from the rotating electric machine 1 to the output gear 30 to the pair of output members 6. In other words, the output gear 30 is drivingly connected to both of the pair of output members 6 via the differential gear mechanism 5. Note that the differential gear mechanism 5 may be a bevel gear type differential gear mechanism, and the output gear 30 may be connected to a differential case portion of the differential gear mechanism 5 so as to rotate integrally with the differential case portion.

[0021] 3, the case 2 includes an integrated motor case 21, a transmission mechanism case 22, and an inverter case 24. Here, "integrated" includes an integrated configuration using fastening members such as bolts, and an integrated configuration using integral molding (for example, casting or aluminizing).

[0022] The motor case portion 21 forms a motor accommodating chamber S1 that accommodates the rotating electric machine 1. That is, the motor case portion 21 covers the radial outside of the rotating electric machine 1. The transmission mechanism case portion 22 forms a transmission mechanism accommodating chamber S2 that accommodates the transmission mechanism 3. That is, the transmission mechanism case portion 22 covers the radial outside of the transmission mechanism 3. The inverter case portion 24 forms an inverter accommodating chamber S4 that accommodates the inverter device 4. Note that, in a modified example, the case 2 may accommodate the first output member 61. In this case, the transmission mechanism case portion 22 covers the radial outside of the transmission mechanism 3 and also covers the radial outside of the first output member 61.

[0023] In the following description, as an example, the case 2 is formed by joining a case member 200, a motor cover member 201, a differential cover member 202, and an inverter cover member 203. The joining method may be fastening with bolts or the like.

[0024] The case member 200 may be formed as a one-piece member (for example, a single member made of a common material formed by die casting). In this case, the motor housing chamber S1 and the transmission mechanism housing chamber S2 may be separated by a single partition wall 26 (see FIG. 3).

[0025] The case member 200 is open in the axial direction A on the first axial side A1 and is open in the axial direction A on the second axial side A2.

[0026] The motor cover member 201 is provided to cover the opening on the first axial side A1 of the case member 200 (i.e., the opening on the first axial side A1 of the motor accommodating chamber S1). The motor cover member 201 may be formed as a one-piece member. The motor cover member 201 may be joined to the end face (joint surface) of the case member 200 on the first axial side A1.

[0027] The differential cover member 202 is provided to cover the opening on the second axial side A2 of the case member 200 (i.e., the opening on the second axial side A2 of the transmission mechanism accommodating chamber S2). The differential cover member 202 may be formed as a one-piece member. The differential cover member 202 may be joined to an end face (joint surface) of the case member 200 on the second axial side A2.

[0028] FIG. 4 is a diagram schematically illustrating an example of a cooling system 8 that can be applied to this embodiment.

[0029] The oil pump 51 mechanically or electrically pumps up oil that accumulates in the lower part of the case 2. In the example shown in Fig. 4, the oil pumped up by the oil pump 51 passes through an oil passage 81 and then through an oil passage 819 that is thermally connected to an object to be cooled 77 (e.g., the rotating electric machine 1). Note that although the oil passage 819 is shown schematically, it may also include an axial oil passage (not shown) of the rotor shaft of the rotating electric machine 1 and spaces within the case 2 (the motor accommodating chamber S1 and the transmission mechanism accommodating chamber S2).

[0030] The oil circulating through the oil passage 81 passes through the oil cooler 9. Cooling water (an example of a cooling medium) is supplied to the oil cooler 9 by a water pump 71 via a cooling water passage 70, and the oil is cooled (the cooling water is heated) by heat exchange between the cooling water and the oil. The cooling water may be supplied to an object to be cooled 77. In this case, the object to be cooled 77 may include the inverter unit 4. For example, a water passage portion 70A may be formed below the inverter unit 4 by a water passage forming member 41 (see FIG. 3 ).

[0031] Next, further features relating to the oil cooler 9 of this embodiment will be described with reference to FIG. 5 and subsequent figures.

[0032] 5 and 6 are schematic explanatory diagrams of a preferred arrangement example of the oil cooler 9 of this embodiment, showing the arrangement (schematic outer shape) of the oil cooler 9 as viewed in the axial direction, along with the schematic outer shape of the case 2. The schematic outer shape of the case 2 shown in FIGS. 5 and 6 may correspond to the outer shape formed by the motor case 21 and the transmission mechanism case 22.

[0033] In this embodiment, the oil cooler 9 is integrally formed with the case 2. Here, the phrase "the oil cooler 9 is integrally formed with the case 2" not only refers to a configuration in which the entire oil cooler 9 is integrally formed with the case 2, but also to a configuration in which a portion of the oil cooler 9 is integrally formed with the case 2. Furthermore, "the oil cooler 9 is integrally formed with the case 2" refers to a configuration in which a portion or all of the oil cooler 9 is formed simultaneously when the case 2 is formed. In this case, the portion of the oil cooler 9 that is integrally formed with the case 2 (a portion or all of the oil cooler 9) is formed from the same material as the case 2 (for example, aluminum).

[0034] Specifically, the oil cooler 9 may be formed integrally with the motor case 21 or with the transmission mechanism case 22. When the oil cooler 9 is formed integrally with the motor case 21, it may be formed integrally on the outside (external side) of the motor case 21, or on the motor housing chamber S1 side of the motor case 21 (a portion that bounds the motor housing chamber S1). When the oil cooler 9 is formed integrally with the transmission mechanism case 22, it may be formed integrally on the outside (external side) of the transmission mechanism case 22, or on the transmission mechanism housing chamber S2 side of the transmission mechanism case 22 (a portion that bounds the transmission mechanism housing chamber S2). The oil cooler 9 may be formed integrally with both the motor case 21 and the transmission mechanism case 22.

[0035] In this embodiment, the oil cooler 9 overlaps the case 2 when viewed in the axial direction. Here, "the oil cooler 9 overlaps the case 2 when viewed in the axial direction" is a concept that includes not only a configuration in which the entire oil cooler 9 overlaps the case 2, but also a configuration in which only a portion of the oil cooler 9 overlaps the case 2.

[0036] 5, the outer shape of the transmission mechanism case 22 protrudes downward (toward the Z2 side) more than the outer shape of the motor case 21 when viewed in the axial direction. In this case, the oil cooler 9 may be provided so as to overlap this protruding region of the outer shape of the transmission mechanism case 22. This prevents the oil cooler 9 from increasing the projected area of ​​the entire vehicle drive device 100 when viewed in the axial direction. In other words, the oil cooler 9 can be provided without increasing the projected area (outer shape) of the entire vehicle drive device 100 when viewed in the axial direction.

[0037] 5, the oil cooler 9 overlaps the rotating electric machine 1 when viewed in the radial direction (not shown). Therefore, in this case, it is possible to prevent the oil cooler 9 from increasing the axial size of the vehicle drive device 100.

[0038] 6, the outer shape of the motor case 21 protrudes further in the X direction (X2) than the outer shape of the transmission mechanism case 22 when viewed in the axial direction. In this case, the oil cooler 9 may be provided so as to overlap this protruding region of the outer shape of the motor case 21. This prevents the oil cooler 9 from increasing the projected area of ​​the entire vehicle drive device 100 when viewed in the axial direction. In other words, the oil cooler 9 can be provided without increasing the projected area (outer shape) of the entire vehicle drive device 100 when viewed in the axial direction.

[0039] 6, the oil cooler 9 overlaps the transmission mechanism case 22 when viewed in the radial direction (not shown). Therefore, in this case, it is possible to prevent the oil cooler 9 from increasing the axial size of the vehicle drive device 100.

[0040] Fig. 7 is a conceptual diagram of a preferred configuration of the oil cooler 9. In Fig. 7, the flow of oil and the flow of cooling water within the oil cooler 9 are schematically shown by arrows R71 and R72. In Fig. 7, the line diagram conceptually shows the partitions (walls) of the flow passages.

[0041] In this embodiment, the oil cooler 9 is integrally formed with the case 2 as described above. This reduces the degree of freedom in the external shape compared to an externally mounted configuration, and it may be difficult to increase the overall size. For this reason, as shown in FIG. 7 , the oil cooler 9 preferably has the oil passage 91 (part of the oil passage 81) and the water passage 72 (part of the cooling water passage 70) through which the cooling water passes adjacent to each other and each has a folded portion 911, 721. This allows the length of the oil passage 91 to be efficiently increased even when the oil cooler 9 is relatively small in size. As a result, heat exchange between the oil and the cooling water within the oil cooler 9 can be promoted.

[0042] 7, there is one turn-back portion 911, 721, but there may be multiple turn-back portions 911, 721. In the example shown in Fig. 7, the oil flow direction (arrow R71) in the oil passage 91 and the cooling water flow direction (arrow R72) in the water passage 72 within the oil cooler 9 are in the same plane, but one flow direction and the other flow direction may be perpendicular to each other, or in other ways.

[0043] Next, further specific examples will be described in multiple examples with reference to Figure 8 onwards. In the following, terms such as "Example 1" and "Example 2" will be used to distinguish between the specific examples.

[0044] 8 and 9 are perspective views of a portion of a vehicle drive device 100A including an oil cooler 9A according to Example 1. For ease of viewing, Fig. 8 and Fig. 9 show a state in which the motor cover member 201 has been removed. Note that Fig. 8 and Fig. 9 are both perspective views viewed from the first axial side A1, but Fig. 8 is a perspective view from below and Fig. 9 is a perspective view from above.

[0045] In the first embodiment, as shown in FIGS. 8 and 9, the oil cooler 9A is integrally formed below the motor case portion 21A in a manner overlapping the transmission mechanism case portion 22A when viewed in the axial direction.

[0046] 10 to 13 are explanatory diagrams of the internal configuration of the oil cooler 9A, and are cross-sectional views taken along a cutting plane parallel to the XZ plane, and are cross-sectional views taken along the A direction toward the first axial side A1 in ascending order from FIG.

[0047] In this first embodiment, the oil cooler 9A is cylindrical with a central axis in a direction (X direction) that intersects the axial direction. The oil cooler 9A has a main body 98A with a cylindrical outer shape and lids 99A-1 and 99A-2 on both sides in the X direction. The main body 98A is integrally formed with the motor case 21A of the case 2A. The oil cooler 9A is provided within the axial range of the rotating electrical machine 1.

[0048] The oil cooler 9A has an oil passage 91A and a water passage 72A therein. The oil passage 91A and the water passage 72A are adjacent to each other.

[0049] The oil passage 91A has a plurality of turn-back portions 911A-1, 911A-2 that move back and forth in the axial direction. Specific oil flows are shown in ascending order by arrows R101 to R104 in Figures 10 to 13. In this case, the oil moves back and forth in the axial direction, and then changes direction at the turn-back portion 911A-2 to flow to an adjacent oil passage portion in a direction intersecting the axial direction (perpendicular to the paper surface). The inlet 913A and outlet 914A of the oil passage 91A are provided on both sides in the direction intersecting the axial direction (perpendicular to the paper surface).

[0050] The water channel 72A has an inlet 723A and an outlet 724A on both sides in the X direction. Cooling water is introduced from the inlet 723A on the X1 side and discharged from the outlet 724A (flow path inside the lid portion 99A-2) on the X2 side. Note that the inlet 723A and the outlet 724A may be reversed.

[0051] According to the first embodiment, the oil cooler 9A can be provided without increasing the projected area (external dimensions) of the entire vehicle drive device 100A as viewed in the axial direction. Furthermore, since the oil cooler 9A is provided within the axial range of the rotating electric machine 1, it is possible to prevent the oil cooler 9A from increasing the axial size of the vehicle drive device 100A.

[0052] Furthermore, according to the present embodiment 1, the oil cooler 9A has an oil passage 91A and a water passage 72A that travel in the X direction, which intersects the axial direction, so that the X direction range of the rotating electric machine 1 can be utilized to efficiently increase the flow path length of the oil passage 91A and the water passage 72A.

[0053] 14 is a diagram schematically illustrating the flow of oil and coolant in the entire vehicle drive device 100A when the oil cooler 9A according to the first embodiment is applied. In FIG. 14, the flow of oil is schematically indicated by arrows R141 to R143, and the flow of coolant is schematically indicated by arrows R145 to R146. Note that in FIG. 14, the oil cooler 9A is schematically illustrated as being separate from the case 2A, but in reality, it is integrally formed as shown in FIGS. 8 and 9.

[0054] 14, the oil cooler 9A is provided adjacent to the lower part of the transmission mechanism housing chamber S2 (where oil accumulates). This shortens the length of the oil passage for guiding oil from the oil pump 51 to the oil cooler 9A, simplifying the oil passage configuration. For example, it is possible to reduce the number of machined parts and cast holes (and the associated cast pins) required to form the oil passage in the case 2.

[0055] FIG. 15 is a perspective view of a portion of a vehicle drive system 100B including an oil cooler 9B according to the second embodiment.

[0056] 15 , in the second embodiment, the oil cooler 9B is integrally formed on the side of the transmission mechanism case 22B in a manner that, as viewed in the axial direction, it overlaps with the motor case 21. Specifically, the oil cooler 9B is integrally formed inside the transmission mechanism case 22B (on the transmission mechanism accommodation chamber S2 side).

[0057] Fig. 16 is an exploded perspective view of the main body 98B and lid 99B of the oil cooler 9B. Figs. 17 to 20 are cross-sectional views of the main body 98B taken along a cut surface parallel to the XZ plane, and are cross-sectional views taken in ascending order from Fig. 17 to Fig. 20 at a position in direction A toward the first axial side A1. Fig. 21 is a perspective view of the lid 99B.

[0058] In the first embodiment, the oil cooler 9B has a cylindrical shape extending in the axial direction. The oil cooler 9B is disposed around the first axis C1. For example, the oil cooler 9B may be disposed over a circumferential range of approximately 120 degrees around the first axis C1. In this case, an efficient arrangement can be achieved by utilizing the space circumferentially outside the small-diameter gear 341 (see FIG. 2) of the reduction mechanism 34. The oil cooler 9B has a main body 98A having a cylindrical outer shape and a lid 99B. The main body 98B is integrally formed with the transmission mechanism case 22B of the case 2B.

[0059] The main body portion 98B is open on both axial sides, but the second axial side A2 is closed by a differential cover member 202, and the first axial side A1 is closed by a lid portion 99B.

[0060] The oil cooler 9B has an oil passage 91B and a water passage 72B therein. The oil passage 91B and the water passage 72B are adjacent to each other.

[0061] The oil passage 91B has a plurality of turn-back portions 911B-1, 911B-2 that move back and forth in the axial direction. The oil passage 91B has an inlet 913B and an outlet 914B on both sides in the circumferential direction of the main body portion 98B. Oil is introduced from the inlet 913B on one side in the circumferential direction of the main body portion 98B and discharged from the outlet 914B on the other side in the circumferential direction. Note that the inlet 913B and the outlet 914B may be reversed.

[0062] The water channel 72B has multiple folded portions 721B-1, 721B-2 that move back and forth in the axial direction. The folded portions 721B-1, 721B-2 are formed by the lid portion 99B. The lid portion 99B has a protrusion 991B that is inserted into the water channel space. The tip side of the protrusion 991B cooperates with the bottom portion 7270 (see FIG. 18) of the axial cavity 727 associated with the water channel 72B in the main body portion 98B to form the folded portion 721B-2 on the axial second side A2. Furthermore, the base side of the protrusion 991B on the lid portion 99B cooperates with the connection portion 7271 (see FIG. 20) between the axial cavities 727 associated with the water channel 72B in the main body portion 98B to form the folded portion 721B-1 on the axial first side A1.

[0063] The water passage 72B has an inlet 723B and an outlet 724B on both sides in the circumferential direction of the main body 98B. Cooling water is introduced from the inlet 723B on one side in the circumferential direction of the main body 98B and discharged from the outlet 724B on the other side in the circumferential direction. Note that the inlet 723B and the outlet 724B may be reversed.

[0064] According to the second embodiment, the oil cooler 9B can be provided without increasing the projected area (external dimensions) of the entire vehicle drive device 100B as viewed in the axial direction. Furthermore, since the oil cooler 9B is provided within the axial range of the transmission mechanism 3 (reduction mechanism 34), it is possible to prevent the oil cooler 9B from increasing the axial size of the vehicle drive device 100B.

[0065] Furthermore, according to this embodiment 2, the oil cooler 9B has an oil passage 91B and a water passage 72B that move back and forth in the axial direction, so that the axial range of the transmission mechanism 3 (reduction mechanism 34) can be utilized to efficiently increase the flow path length related to the oil passage 91B and the water passage 72B.

[0066] FIG. 22 is a perspective view of a portion of a vehicle drive system 100C including an oil cooler 9C according to the third embodiment.

[0067] In the third embodiment, as shown in Fig. 22, the oil cooler 9C is integrally formed with a differential cover member 202C. In this case, the differential cover member 202C forms a part of the outer periphery that covers the radial outside of the transmission mechanism 3 (reduction mechanism 34). In this case, the oil cooler 9C is also provided radially outside the transmission mechanism 3 (reduction mechanism 34) in a manner that overlaps with the motor case 21 when viewed in the axial direction, similar to the second embodiment described above.

[0068] The third embodiment also provides the same effects as the second embodiment.

[0069] FIG. 23 is a perspective view of a portion of a vehicle drive device 100D including an oil cooler 9D according to the fourth embodiment.

[0070] 23 , in the fourth embodiment, the oil cooler 9D is integrally formed with a differential cover member 202D. In this case, the differential cover member 202D may form a part of the outer periphery that covers the radial outside of the transmission mechanism 3 (reduction mechanism 34). In this case, the oil cooler 9D is also provided radially outside the transmission mechanism 3 (reduction mechanism 34) in a manner that overlaps with the motor case 21 when viewed in the axial direction, similar to the second embodiment described above.

[0071] The oil cooler 9D according to the fourth embodiment differs from the oil cooler 9C according to the third embodiment in its flow path configuration. Specifically, the oil cooler 9D has oil passages formed within the XZ plane so that oil flows back and forth in the Z direction while also flowing in the X direction. On the other hand, the oil cooler 9C has oil passages formed within the XZ plane so that oil flows back and forth in the X direction while also flowing in the Z direction. In the oil cooler 9D according to the fourth embodiment (as in the third embodiment), the dimension in the Z direction is significantly larger than the dimension in the X direction. Therefore, the oil cooler 9D according to the fourth embodiment can reduce the number of turns (returns) of the oil passage compared to the oil cooler 9C according to the fourth embodiment. This allows for smoother oil flow, reduces pressure loss, and improves efficiency.

[0072] The fourth embodiment also provides the same effects as the second embodiment.

[0073] Although each embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0074] DESCRIPTION OF SYMBOLS 1... Rotating electric machine, 2, 2A, 2B... Case, 3... Transmission mechanism, 9, 9A, 9B, 9C... Oil cooler, 21, 21A, 21B... Motor case portion (first outer peripheral portion), 22, 22A, 22B... Transmission mechanism case portion (second outer peripheral portion), 91, 91A, 91B... Oil passage, 911, 911A-1, 911A-2, 911B-1, 911B-2... Turned-back portion, 72, 72A, 72B... Water passage, 721, 721B-1, 721B-2... Turned-back portion

Claims

1. A vehicle drive device comprising: a rotating electric machine; a transmission mechanism that transmits driving force from the rotating electric machine to wheels; a case that houses the rotating electric machine and the transmission mechanism and in which oil accumulates at the bottom; and an oil cooler that is formed integrally with the case and performs heat exchange between the oil and a cooling medium, wherein the case has a first outer periphery that covers the radial outside of the rotating electric machine and a second outer periphery that covers the radial outside of the transmission mechanism, and the oil cooler is formed on one of the first outer periphery and the second outer periphery, and when viewed in the axial direction, a heat exchange portion overlaps with the other of the first outer periphery and the second outer periphery.

2. A vehicle drive device as described in claim 1, wherein the oil cooler has an oil passage through which the oil flows and a water passage through which the cooling medium flows that are adjacent to each other, and at least one of the oil passage and the water passage has at least one folded portion.

3. The vehicle drive device according to claim 1 or 2, wherein the oil cooler is disposed below the rotating electric machine in a manner that overlaps with the second outer periphery when viewed in the axial direction.

4. The vehicle drive device according to claim 1 or 2, wherein the oil cooler is disposed to the side of the transmission mechanism in a manner that overlaps with the first outer periphery when viewed in the axial direction.

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