Vehicle drive systems

Abstract

Disclosed is a vehicular drive device comprising: a rotating electric machine; a case that houses the rotating electric machine; and a flow path formation member that is disposed between an outer circumferential surface of the rotating electric machine and an inner circumferential surface of the case to form a refrigerant flow path through which a refrigerant passes, wherein the flow path formation member has a cylindrical shape and is fastened to the case on one end side thereof in the axial direction, and, when assuming a rectangle that circumscribes the outer shape of the rotating electric machine when viewed in the axial direction and that has two sides parallel to the vertical direction, a fastening portion of the flow path formation member with respect to the case overlaps at least one corner among four corners of the rectangle when viewed in the axial direction.

Description

Technical Field

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

Background Art

[0002] A technique is known in which a flow path forming member that forms a refrigerant flow path (cooling water passage) around a rotating electric machine is fastened to a case (outer case) that mates with the flow path forming member (inner case).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art as described above, it is difficult to fasten the rotating electric machine together with the flow path forming member to the case without significantly increasing the size of the drive device for a vehicle.

[0005] Therefore, on one aspect, an object of the present disclosure is to fasten the rotating electric machine together with the flow path forming member to the case without significantly increasing the size of the drive device for a vehicle.

Means for Solving the Problems

[0006] On one aspect, a rotating electric machine, a case that houses the rotating electric machine, and a flow path forming member that is disposed between an outer peripheral surface of the rotating electric machine and an inner peripheral surface of the case and forms a refrigerant flow path through which refrigerant passes are provided. The flow path forming member has a cylindrical shape and is fastened to the case on one end side in the axial direction. Assuming a rectangle that circumscribes the outer shape of the rotating electric machine when viewed in the axial direction and has two sides parallel in the vertical direction, the fastening portion of the flow path forming member to the case is provided such that, when viewed in the axial direction, it overlaps with at least one of the four corners of the rectangle. [Effects of the Invention]

[0007] In one respect, this disclosure makes it possible to fasten a rotating electric machine together with a flow path forming member to a case without significantly increasing the size of the vehicle drive unit. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic top view diagram showing the mounting configuration of the vehicle's drive system. [Figure 2] This is a cross-sectional view of a vehicle drive system. [Figure 2A] This is a skeleton diagram showing a vehicle drive system. [Figure 3] This is a schematic side view showing a vehicle drive system according to this embodiment. [Figure 4] This is a perspective view of the channel forming member. [Figure 4A] This is an enlarged view of section Q4 in Figure 4. [Figure 5] This is a schematic diagram of the refrigerant flow path formed by the flow path forming member. [Figure 6A] This is a cross-sectional view of a portion of the refrigerant flow path. [Figure 6B] This is a schematic side view showing the positional relationship between the first output component, the refrigerant supply unit, and the refrigerant discharge unit. [Figure 6C] This is an enlarged view of section Q6 in Figure 2. [Figure 7] This is an explanatory diagram illustrating the preferred arrangement of fastening parts, and is a schematic side view showing a vehicle drive system according to this embodiment. [Figure 7A] Figure 7 is a schematic diagram that shows a portion of the fastening arrangement according to the comparative example superimposed with dotted lines. [Figure 8]This is an explanatory diagram illustrating the preferred arrangement of the fastening parts, and is a side view that schematically shows the relationship with the wiring connector. [Figure 9] This is a schematic side view showing the vehicle drive system according to this embodiment, as viewed from the A2 side. [Modes for carrying out the invention]

[0009] The following describes each embodiment in detail with reference to the attached drawings. Note that the dimensional ratios in the drawings are merely examples and are not exhaustive. Furthermore, some shapes and other details in the drawings may be exaggerated for illustrative purposes.

[0010] In the following explanation, the Y direction (see Figure 3, etc.) corresponds to the vertical direction of the vehicle drive unit 100 in its operating state, that is, the vertical direction when the vehicle drive unit 100 is positioned in its operating orientation. The Y1 side and Y2 side correspond to the upper and lower sides along the Y direction. Note that the vertical direction does not necessarily have to be parallel to the vertical direction, but only if it is predominantly vertical. Furthermore, if the vertical direction of the vehicle drive unit 100 in its operating state is significantly inclined vertically, the vertical direction in the following explanation may be interpreted as the vertical direction of the vehicle drive unit 100 as a standalone unit (product) in a flat position (the same applies to the horizontal direction). In addition, the direction of each component in the following explanation represents the direction when they are assembled to the vehicle drive unit 100. Furthermore, terms related to the dimensions, arrangement direction, arrangement position, etc., of each component are concepts that include differences due to errors (errors that are within the range that can be tolerated in manufacturing). Direction A (see Figure 2, etc.) corresponds to the axial direction, and Figure 2, etc. defines the A1 side and the A2 side along the A direction. Direction X (see Figure 3, etc.) is perpendicular to both the A and Y directions, and Figure 3, etc. defines the X1 side and the X2 side along the X direction.

[0011] In this specification, "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), including 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 that transmit rotation at the same speed or with speed change (for example, shafts, gear mechanisms, belts, chains, etc.). Note that the transmission members may include engagement devices (for example, friction engagement devices, meshing engagement devices, etc.) that selectively transmit rotation and driving force.

[0012] Also, in this specification, "communication" refers to a state in which two spatial elements are in fluid communication with each other. That is, it refers to a state in which fluid can flow back and forth between two spatial elements. At this time, the two spatial elements may communicate directly or indirectly (that is, via other spatial elements).

[0013] In this specification, "rotating electrical machine" is used as a concept that includes any of a motor (electric motor), a generator (generator), and a motor-generator that performs the functions of both a motor and a generator as required. Also, in this specification, regarding the arrangement of two members, "overlapping in a specific direction view" means that when a virtual straight line parallel to the line-of-sight direction is moved in each direction orthogonal to the virtual straight line, there is at least a part of a region where the virtual straight line intersects both of the two members. Also, in this specification, regarding the arrangement of two members, "the arrangement regions in a specific direction overlap" means that at least a part of the arrangement region in a specific direction of one member is included in the arrangement region in a specific direction of the other member.

[0014] FIG. 1 is a schematic top view showing the mounting state of the vehicle drive device 100 in the vehicle VC. FIG. 2 is a cross-sectional view of the vehicle drive device 100. FIG. 2A is a skeleton view showing the vehicle drive device 100.

[0015] As schematically shown in Figure 2A, the vehicle drive unit 100 comprises a rotating electric machine 1, a pair of output members 6 that are driven and connected to a pair of wheels W (see Figure 1), and a transmission mechanism 3 that transmits driving force between the rotating electric machine 1 and the pair of output members 6. The vehicle drive unit 100 further comprises a case 2 that houses the rotating electric machine 1. The case 2 also houses the pair of output members 6 and the transmission mechanism 3. In a modified example, the case 2 may house only one of the pair of output members 6. Furthermore, the vehicle drive unit 100 can be applied to any vehicle having a rotating electric machine 1, such as electric vehicles or hybrid vehicles, and the drive system can be any vehicle, such as front-wheel drive or rear-wheel drive. In addition, the drive source may be only an engine (internal combustion engine).

[0016] One of a pair of output members 6, the first output member 61, is driven and connected to the first wheel W1, one of a pair of wheels W, and the other of the pair of output members 6, the second output member 62, is driven and connected to the second wheel W2, the other of the pair of wheels W. As shown in Figure 1, the vehicle VC on which the vehicle drive unit 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, for example via a constant velocity joint, and the second drive shaft 64 is connected to the second wheel W2, for example via a constant velocity joint. The first output member 61 is connected to the first drive shaft 63 so as to rotate integrally with the first drive shaft 63, and the second output member 62 is connected to the second drive shaft 64 so as to rotate integrally with the second drive shaft 64. The first output member 61 may be in the form of an intermediate shaft.

[0017] The vehicle drive unit 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 driving the vehicle VC on which the vehicle drive unit 100 is mounted. In other words, the rotating electric machine 1 is the driving force source for the pair of wheels W. The pair of wheels W are a left and right pair of wheels on the vehicle VC (for example, a left and right pair of front wheels, or a left and right pair of rear wheels). The rotating electric machine 1 may be, for example, an AC rotating electric machine driven by a three-phase AC.

[0018] As shown in Figure 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 positioned on the first axis C1, and the pair of output members 6 are positioned on a second axis C2, which is different from the first axis C1. The first axis C1 and the second axis C2 are axes (virtual axes) that are positioned parallel to each other. The transmission mechanism 3 is provided with an output gear (ring gear) 30 that is driven and 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).

[0019] The rotating electric machine 1 is, for example, an inner rotor type. In the rotating electric machine 1, a rotor 14 that can rotate around the first axis C1 is arranged radially inside the stator 11 (see Figure 2).

[0020] The transmission mechanism 3 includes a reduction mechanism 34 in the power transmission path between the rotating electric machine 1 and the output gear 30. The reduction mechanism 34 is optional and may include a reduction mechanism using a counter gear or a reduction mechanism using planetary gears. In this embodiment, as an example, the reduction mechanism 34 includes a planetary gear mechanism and is arranged coaxially with the rotating electric machine 1. The output gear (carrier) 342 of the reduction mechanism 34 meshes radially with the output gear 30 of the differential gear mechanism 5. Such a vehicle drive system 100 can have a compact configuration consisting of two shafts (first shaft C1 and second shaft C2). In a modified example, the vehicle drive system 100 may have three or more shafts.

[0021] In this embodiment, the reduction mechanism 34 is arranged coaxially with the rotating electric machine 1 (i.e., on the first axis C1) and is driven and connected to the rotating electric machine 1. In this embodiment, as an example, the rotor 14 of the rotating electric machine 1 rotates integrally with the input member 16 together with the sun gear 341 of the reduction mechanism 34.

[0022] Furthermore, 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 a pair of output members 6. In the example shown in Figure 2, the differential gear mechanism 5 distributes the rotation of the output gear 30 to the first side gear 51 and the second side gear 52. The differential gear mechanism 5 may be arranged coaxially with the pair of output members 6 (i.e., on the second shaft C2). The differential gear mechanism 5 may be a bevel gear type differential gear mechanism, and the output gear 30 may be connected to the differential case portion 50 of the differential gear mechanism 5 so as to rotate integrally with the differential case portion 50.

[0023] Next, with reference to Figure 3 and subsequent figures, the water-cooling structure of the rotating electric machine 1 according to this embodiment and its related components (such as the flow path forming member 90) will be described.

[0024] Figure 3 is a schematic side view showing the vehicle drive unit 100 according to this embodiment. In Figure 3, the motor cover member 201 is omitted from the illustration so that the state inside the motor housing chamber S1 can be seen. Also in Figure 3, the inverter device 70 inside the inverter case 24 is schematically shown by a dotted line. Figure 4 is a perspective view of the flow path forming member 90. In Figure 4 (and similarly in Figure 5), the positions of the inlet 95 and outlet 96 with respect to the refrigerant flow path 300 are schematically shown as projections (dotted circle). Figure 4A is an enlarged view of part Q4 in Figure 4. Figure 5 is a schematic diagram of the refrigerant flow path 300 formed by the flow path forming member 90, and is an explanatory diagram showing the outer surface of the flow path forming member 90 unfolded on a plane. Figure 6A is a cross-sectional view of a part of the refrigerant flow path 300 (the part along line AA in Figure 5). Figure 6B is a schematic side view showing the positional relationship between the first output member 61 and the refrigerant supply unit 40 and the refrigerant discharge unit 42. Figure 6C is an enlarged view of section Q6 in Figure 2.

[0025] The water-cooling structure of the rotating electric machine 1 according to this embodiment is a structure for cooling the rotating electric machine 1 with cooling water. The cooling water may be water containing, for example, LLC (Long Life Coolant), and may be circulated by a water pump (not shown). A heat dissipation part such as a radiator (not shown) may be provided in the cooling water circulation path. In addition to cooling the rotating electric machine 1, the cooling water may also be used to cool other components, such as the inverter device 70 that is electrically connected to the rotating electric machine 1.

[0026] The water-cooling structure of the rotating electric machine 1 according to this embodiment may include a refrigerant supply unit 40, a refrigerant discharge unit 42, and a flow path forming member 90, as shown in Figure 4.

[0027] The refrigerant supply unit 40 communicates with the discharge side of, for example, a water pump (not shown) and supplies cooling water to the refrigerant flow path 300 (described later) formed by the flow path forming member 90.

[0028] The refrigerant discharge section 42 communicates with the suction side of, for example, a water pump (not shown), and supplies (discharges) cooling water from the refrigerant flow path 300 (described later) formed by the flow path forming member 90 to the water pump (not shown).

[0029] The refrigerant supply unit 40 and the refrigerant discharge unit 42 may be provided above and below the first output member 61, as shown in Figure 6B. In this case, the refrigerant supply unit 40 and the refrigerant discharge unit 42 can be constructed by effectively utilizing the space around the first output member 61.

[0030] As shown in Figure 4, the flow path forming member 90 has a cylindrical shape with an inner circumferential surface that is radially opposite to the outer circumferential surface of the rotating electric machine 1. The flow path forming member 90 forms a refrigerant flow path 300 around the rotating electric machine 1.

[0031] The flow path forming member 90 may be made of a material with good thermal conductivity, such as aluminum. In this embodiment, as an example, the flow path forming member 90 is fitted to the stator core 12 of the stator 11 by shrink fitting, for example. This increases the contact (compression) between the flow path forming member 90 and the stator core 12, and reduces the thermal resistance between the flow path forming member 90 and the stator core 12. In other embodiments, the flow path forming member 90 may be integrally formed with the stator core 12 by casting or the like. Alternatively, the flow path forming member 90 may be formed as part of the case 2.

[0032] In this embodiment, the flow path forming member 90 is, for example, in the form of an inner case fastened to the case 2, as shown in Figure 3. In this case, the flow path forming member 90 has a plurality of fastening portions 500 on one axial end, as shown in Figure 3. Preferred arrangements of the plurality of fastening portions 500 will be described later.

[0033] The flow path forming member 90 is inserted into the cylindrical space (motor housing chamber S1) of the case 2. At this time, the outer circumferential surface of the flow path forming member 90 faces radially with respect to the inner circumferential surface (the inner circumferential surface that defines the multiple fastening parts 500) of the motor case portion 21 (see Figure 2) of the case 2. Hereafter, the inner circumferential surface of the case 2 that surrounds the flow path forming member 90 in this manner will also be referred to as the "flow path forming surface 209 of the case 2". The inner diameter of the flow path forming surface 209 of the case 2 may be a constant value that is larger than the basic outer diameter of the stator core 12 by the basic wall thickness t0 (see Figure 6A) of the flow path forming member 90.

[0034] The flow path forming member 90 cooperates with the flow path forming surface 209 of the case 2 to form a refrigerant flow path 300. Specifically, the refrigerant flow path 300 is formed radially between the outer circumferential surface of the flow path forming member 90 and the flow path forming surface 209 of the case 2.

[0035] The refrigerant flow path 300 may extend circumferentially so that cooling water flows circumferentially throughout the entire circumferential direction. The refrigerant flow path 300 may also be formed so as to be radially opposite the outer circumferential surface of the stator core 12 over the entire axial direction of the stator core 12 of the rotating electric machine 1. The refrigerant flow path 300 is closed at both axial ends. For example, between the flow path forming member 90 and the flow path forming surface 209 of the case 2, a sealing member 97 (see Figure 6C) may be provided at both axial ends of the flow path forming member 90, extending over the entire circumferential direction.

[0036] In this embodiment, the refrigerant flow path 300 is broadly divided into a first circumferential section SC1, a second circumferential section SC2, a third circumferential section SC3, and a fourth circumferential section SC4, as shown in Figures 4 and 5.

[0037] The first circumferential section SC1 is a section that includes an inlet 95. A refrigerant supply unit 40 is connected to the inlet 95. Therefore, cooling water is introduced into the refrigerant flow path 300 from the inlet 95. The inlet 95 may be in the form of an opening at the end of the refrigerant supply unit 40.

[0038] The second circumferential section SC2 is a section that includes an outlet section 96. A refrigerant discharge section 42 is connected to the outlet section 96. Therefore, the cooling water introduced into the refrigerant flow path 300 is discharged outside the refrigerant flow path 300 via the outlet section 96. The outlet section 96 may take the form of an opening at the end of the refrigerant discharge section 42.

[0039] The third circumferential section SC3 extends circumferentially between the first circumferential section SC1 and the second circumferential section SC2, and may be the section with the longest circumference. The flow path forming member 90 has a convex portion 91 that protrudes radially in the third circumferential section SC3 in a manner that reduces the cross-sectional area of ​​the refrigerant flow path 300. In this embodiment, the convex portion 91 is in the form of a convex ridge or rib that extends continuously in the circumferential direction, and is formed in a manner in which multiple convex portions are arranged in the axial direction. However, in other embodiments, the convex portion 91 may be realized in other forms or arrangements. For example, cylindrical convex portions may be arranged in a staggered pattern. The upper surface (radially outer surface) of the convex portion 91 may abut radially with the flow path forming surface 209 of the case 2, or it may be slightly spaced apart from the flow path forming surface 209 of the case 2. In any case, the portion of the refrigerant flow path 300 in the third circumferential section SC3 is mainly formed by the portion where the convex portion 91 is not formed.

[0040] The fourth circumferential section SC4 may be a section that extends in the circumferential direction between the first circumferential section SC1 and the second circumferential section SC2, and whose circumference is significantly shorter than that of the third circumferential section SC3. The flow path forming member 90 does not need to have protrusions such as the convex portion 91 in the fourth circumferential section SC4. In this embodiment, the flow path forming member 90 has a basically flat surface (outer surface) in the fourth circumferential section SC4.

[0041] In this embodiment, when cooling water is introduced into the inlet 95 of the refrigerant flow path 300, it flows axially through the first circumferential section SC1 (see arrow R52 in Figure 5) and is then distributed to the third circumferential section SC3 and the fourth circumferential section SC4 (see arrows R51 and R53 in Figure 5). The cooling water flowing circumferentially through the third circumferential section SC3 (see arrows R51 and R55 in Figure 5) then flows axially (see arrow R54 in Figure 5) and is discharged from the outlet 96 when it reaches the second circumferential section SC2. The cooling water flowing circumferentially (and possibly having an axial component) through the fourth circumferential section SC4 (see arrow R53 in Figure 5) then flows axially (see arrow R54 in Figure 5) and is discharged from the outlet 96 when it reaches the second circumferential section SC2.

[0042] Generally, fluids tend to flow through channels with low resistance. In this embodiment, however, there are resistive elements such as the protrusions 91 in the third circumferential section SC3. Therefore, if there is a channel between the inlet 95 and the outlet 96 with significantly lower resistance than the third circumferential section SC3, cooling water may not flow sufficiently into the third circumferential section SC3. In this case, the cooling (cooling by cooling water) of the portion of the stator core 12 that is radially opposite to the third circumferential section SC3 may be insufficient. In particular, if the resistance of the channel portion from the inlet 95 to the outlet 96 via the fourth circumferential section SC4 is significantly lower than in this embodiment, as described later, the cooling (cooling by cooling water) of the portion radially opposite to the third circumferential section SC3 may be insufficient.

[0043] Therefore, in this embodiment, the flow path structure in the fourth circumferential section SC4 may be adapted so that the pipeline loss coefficient in the fourth circumferential section SC4 is equivalent to the pipeline loss coefficient in the third circumferential section SC3. Note that the pipeline loss coefficient is calculated as: Pipeline loss coefficient = (pressure loss) / (flow rate) α It may be evaluated as such. However, α > 1. Alternatively, from a similar viewpoint, the flow path structure in the fourth circumferential section SC4 may be adapted so that the flow rate in the fourth circumferential section SC4 is equivalent to the flow rate in the third circumferential section SC3. This makes it possible to make the flow rate of the cooling water (and the resulting cooling capacity) flowing through the refrigerant flow path 300 uniform over the circumferential direction.

[0044] However, the flow rate in the fourth circumferential section SC4 and the flow rate in the third circumferential section SC3 may correspond to the ratio of the circumference of the fourth circumferential section SC4 to the circumference of the third circumferential section SC3. This is because a longer circumference is useful for achieving a higher cooling capacity (i.e., maintaining a low temperature of the cooling water even downstream).

[0045] In this embodiment, the maximum radial width of the cross-section of the refrigerant flow path 300 is smallest in the fourth circumferential section SC4 and largest in the third circumferential section SC3, among the first circumferential section SC1 to the fourth circumferential section SC4. This allows for a relatively large resistance in the fourth circumferential section SC4, thereby ensuring an appropriate flow rate of cooling water through the third circumferential section SC3. In this embodiment, since a protrusion 91 is provided in the third circumferential section SC3, the maximum radial width of the cross-section of the refrigerant flow path 300 in the third circumferential section SC3 occurs in the portion without the protrusion 91.

[0046] Furthermore, in this embodiment, when the maximum value of the radial width of the cross-section of the refrigerant flow path 300 is set to h1 to h4 (see Figure 6A, however h2 is not shown) in each of the first circumferential section SC1 to the fourth circumferential section SC4, then h4

[0047] ​In this embodiment, the flow path forming member 90 is positioned between the stator core 12 and the flow path forming surface 209 of the case 2, as described above, and the radial distance between the stator core 12 and the flow path forming surface 209 of the case 2 is substantially constant throughout the circumferential direction (i.e., a constant value corresponding to the basic wall thickness t0). Therefore, in this embodiment, the h4 described above The relationship t1 > t3 and t4 > t2 > t3 holds. In other words, for the fourth circumferential section SC4, when the thickness of the portion excluding the protrusion 91 is t4, the relationship t4 > t1 > t3 and t4 > t2 > t3 holds. Note that in this case, t1 = t2 or t1 ≈ t2 may also be true. For example, t1 = (t4 + t3) / 2 may be true.<h1>

[0048] The portion of the flow path forming member 90 that forms the refrigerant flow path 300 is substantially the portion through which the refrigerant passes. For example, it may be a portion in the radially opposite direction to the stator core 12, or it may be a portion in the axial range between the inlet portion 95 and the outlet portion 96.

[0049] In this embodiment, if there is a relatively large difference in wall thickness in the flow channel forming member 90, stress concentration is likely to occur due to this difference. In particular, in this embodiment, since the flow channel forming member 90 is shrink-fitted, stress concentration during shrink-fitting is likely to be a problem. In addition, since the flow channel forming member 90 can shrink due to the heat from the stator core 12 and the influence of cooling water, thermal stress is likely to occur.

[0050] In contrast, in this embodiment, although there is a relatively large difference in wall thickness (=t4-t3) in the flow channel forming member 90 between the fourth circumferential section SC4 and the third circumferential section SC3, the first circumferential section SC1 and the second circumferential section SC2 can mitigate this difference in wall thickness. Specifically, between the fourth circumferential section SC4 and the third circumferential section SC3, there are the first circumferential section SC1 and the second circumferential section SC2, which have intermediate wall thicknesses. In this way, in this embodiment, the flow channel forming member 90 can mitigate the difference in wall thickness (=t4-t3) between the fourth circumferential section SC4 and the third circumferential section SC3 in the first circumferential section SC1 and the second circumferential section SC2. As a result, the stress problem that may arise in the flow channel forming member 90 due to the relatively large difference in wall thickness can be reduced or eliminated.

[0051] Furthermore, as in this embodiment, the protrusions 91 in the flow channel forming member 90 similarly create differences in wall thickness, making it easier for stress concentration to occur at the edges of the protrusions 91. In this regard, if the circumferential end position of the protrusions 91 is set at the boundary between the third circumferential section SC3 and the first and second circumferential sections SC1 and SC2, stress concentration is likely to occur at that boundary. That is, in this case, at the boundary, stress caused by the difference in wall thickness (=t1 or t2-t3) between the third circumferential section SC3 and the first and second circumferential sections SC1 and SC2, and stress caused by the formation of the protrusions 91 are likely to occur simultaneously.

[0052] Therefore, in this embodiment, the protrusion 91 preferably terminates in the first circumferential section SC1 and the second circumferential section SC2, as shown in Figures 4 and 5. That is, the protrusion 91 in the third circumferential section SC3 preferably extends continuously into a part of the first circumferential section SC1 that connects to the third circumferential section and a part of the second circumferential section SC2 that connects to the third circumferential section SC3. This reduces stress concentration that may occur at the boundary between the third circumferential section SC3 and the first and second circumferential sections SC1 and SC2.

[0053] In this embodiment, the fourth circumferential section SC4 of the flow path forming member 90 intersects the straight line L6 connecting the axis of the first output member 61 (second axis C2) and the axis of the rotating electric machine 1 (first axis C1) when viewed in the axial direction (see Figure 6B). As a result, the refrigerant supply unit 40 and the refrigerant discharge unit 42 can be arranged above and below the axis of the first output member 61 (second axis C2), as described above, and potentially dead space can be efficiently utilized.

[0054] Next, with reference to Figures 4, 7, and 8, a preferred example of the arrangement of the fastening portion 500 of the flow path forming member 90 will be described.

[0055] Figure 7 is a schematic side view showing the vehicle drive unit 100 according to this embodiment. Figure 8 is an explanatory diagram of the preferred arrangement of the fastening portion 500 and is a schematic side view showing its relationship with the wiring connector 802. In Figure 8, the fastening portion 500 and the wiring connector 802, which are located at different positions in the axial direction, are shown in the same side view for explanatory purposes.

[0056] In the following, a preferred example of the arrangement of the fastening portion 500 will be described, assuming (virtually) a rectangle (in this case, a square) 600 that circumscribes the outer shape of the rotating electric machine 1 when viewed in the axial direction and has two sides parallel in the vertical direction (see Figure 7). Note that the outer shape of the rotating electric machine 1 related to the rectangle 600 may be the outer shape of the stator core 12 (the basic outer shape which is a circle centered on the axis of the rotating electric machine 1).

[0057] As shown in Figures 4 and 7, the fastening portion 500 is provided at the A1 side end of the flow path forming member 90. The fastening portion 500 protrudes radially outward from the circular outer shape of the flow path forming member 90 when viewed in the axial direction. The fastening portion 500 may be formed integrally with the flow path forming member 90 or it may be a separate part. The fastening portion 500 is fastened to the case 2 by bolts (not shown) (see bolt holes BT4). For example, the fastening portion 500 may be fastened to the axial A1 side end face of the motor case portion 21 (see Figure 2) surrounding the rotating electric machine 1. This firmly fixes the flow path forming member 90 to the case 2 via the fastening portion 500. If the fastening portion 500 is a separate part from the flow path forming member 90, the fastening portion may be in the form of a plate and may restrain the axial displacement of the flow path forming member by axially contacting the axial end face of the flow path forming member. Such plate-shaped fastening portion may restrain the circumferential displacement of the flow path forming member by fitting into a recess that may be formed on the axial end face of the flow path forming member.

[0058] Preferably, the fastening portion 500 overlaps with at least one of the four corners CN1 to CN4 of the rectangle 600 when viewed in the axial direction. In the example shown in Figure 3, as shown in Figure 7, the fastening portion 500 overlaps with the upper (Y1 side) corner CN1 and the lower (Y2 side) corner CN2 of the four corners CN1 to CN4 of case 2 when viewed in the axial direction. Here, when the fastening portion 500 overlaps with a corner when viewed in the axial direction, it may mean that part or all of the fastening portion 500 overlaps with a corner when viewed in the axial direction. For example, when the fastening portion 500 overlaps with a corner when viewed in the axial direction, it may mean that the bolt (not shown) related to the fastening portion 500 (see bolt hole BT4) overlaps with a corner when viewed in the axial direction. Also, the corner that the fastening portion 500 overlaps with when viewed in the axial direction may be the area outside the rotating electric machine 1 of the rectangle 600 when viewed in the axial direction.

[0059] More specifically, looking at the axial direction, the angles around the axis of the rotating electric machine 1 are defined as follows: the horizontal line Lh passing through the axis of the rotating electric machine 1 (on the first axis C1) is set to 0 degrees or 180 degrees, and the vertical line Lv is set to 90 degrees or 270 degrees. In this case, corners CN1 and CN3 are on the first line L1 (a line passing through the axis of the rotating electric machine 1) at an angle of 45 degrees (or 225 degrees), as shown in Figure 7, and corners CN2 and CN3 are on the second line L2 (a line passing through the axis of the rotating electric machine 1) at an angle of 135 degrees (or 315 degrees). Then, when the four regions divided by the lines Lh and Lv in the view of Figure 7 are designated as the first to fourth quadrants, "the fastening portion 500 coincides with a corner (one of CN1 to CN4) when viewed in the axial direction" means "the first line L1 or the second line L2 passing through the corner passes through the fastening portion 500 in the same quadrant as the corner, and the fastening portion 500 and the rotating electric machine 1 coincide when viewed in the horizontal direction." For example, the first line L1 passes through the fastening portion 500 that coincides with corner CN1 in the first quadrant, and the second line L2 passes through the fastening portion 500 that coincides with corner CN2 in the second quadrant, and when viewed in the horizontal direction, the fastening portion 500 and the rotating electric machine 1 coincide.

[0060] However, if the fastening portion 500 does not adequately fix the flow path forming member 90 (fixing it to the case 2), problems such as leakage of cooling water from the refrigerant flow path 300 formed by the flow path forming member 90 or intrusion of oil into the refrigerant flow path 300 may occur. To prevent such problems, and from the viewpoint of improving the reliability of the fastening portion 500 fixing the flow path forming member 90, it is desirable that the fastening portions 500 be arranged at three or more locations at approximately equal intervals along the circumferential direction (for example, at 120-degree intervals in the case of three locations).

[0061] For example, in Figure 7A, fastening portions 500' arranged at 120-degree intervals are hypothetically shown by dotted lines. In this case, as can be seen from the fact that the fastening portions 500' protrude from the outer shape of case 2 (outer shape viewed in the axial direction), it is easy to increase the size of case 2 (and consequently the size of the vehicle drive unit 100). In particular, in a layout such as this embodiment, where the first output member 61 is arranged in the vicinity of the rotating electric machine 1, it is difficult to establish three or more fastening portions in a manner that does not interfere with the first output member 61.

[0062] In this embodiment, as described above, two of the three fastening portions 500 overlap the upper (Y1) corner CN1 and the lower (Y2) corner CN2 on the X1 side when viewed in the axial direction. As a result, as shown in Figure 7, the three fastening portions 500 can be arranged at relatively equal intervals along the circumferential direction without increasing the size of the case 2 (and consequently the size of the vehicle drive unit 100) and without interfering with the first output member 61. Note that the relatively equal intervals may be significantly different angles from, for example, 120 degrees, but the relatively equal intervals ensure the necessary fixing strength throughout the entire circumferential direction. For example, when viewed in the axial direction, the center of the flow path forming member 90 (on the first axis C1) can be positioned within the triangle formed by connecting the bolts (not shown) of the three fastening portions 500 (see bolt holes BT4). This ensures high reliability in fixing the flow path forming member 90 by the fastening portion 500, while reducing the size of the case 2 (and consequently the size of the vehicle drive unit 100).

[0063] Furthermore, in this embodiment, two bolts (not shown) (see bolt hole BT4) are fastened to each of the three fastening portions 500. This further enhances the reliability of the fastening portions 500 in fixing the flow path forming member 90.

[0064] Incidentally, when viewed in the axial direction, the region overlapping with corner CN1 of the four corners CN1 to CN4 is suitable as a wiring region for the inverter case 24. This is because this region is on the upper side where the inverter case 24 is located. Furthermore, in particular, when the inverter case 24 extends beyond the first axis C1 towards X1 when viewed in the axial direction, wiring into the inverter case 24 becomes easier.

[0065] In this embodiment, a wiring connector 802 for electronic components (not shown) is provided in the region between the rotating electric machine 1 and the reduction mechanism 34 in the axial direction, and which overlaps with the corner CN1 when viewed in the axial direction. In this case, the electronic components (not shown) may be low-voltage electronic components arranged in the motor housing chamber S1, and may include, for example, a sensor (e.g., a resolver) for detecting the rotation angle of the rotating electric machine 1, or an oil temperature sensor.

[0066] In this case, when viewed in the axial direction, one of the three fastening portions 500 will overlap with the wiring connector 802 at the corner CN1. This allows the wiring connector 802 and fastening portion 500 to be efficiently implemented in a manner that reduces the size of the case 2 (and consequently the size of the vehicle drive unit 100). In other words, when the case 2 extends to a region that overlaps with the corner CN1 when viewed in the axial direction due to the provision of the wiring connector 802, the increase in the size of the case 2 caused by the fastening portion 500 can be prevented by arranging the fastening portion 500 to overlap with the corner CN1 when viewed in the axial direction.

[0067] Next, with reference to Figure 9, the preferred positional relationship between the catch tank 920 and the fastening portion 500 will be described.

[0068] Figure 9 is a schematic side view showing the vehicle drive unit 100 according to this embodiment as viewed from the A2 side. Hereinafter, the portion of the transmission mechanism housing chamber S2 that houses the reduction mechanism 34 will also be referred to as the "reduction mechanism housing chamber S21," and the portion that houses the differential gear mechanism 5 will also be referred to as the "differential gear housing chamber S22."

[0069] As shown in Figure 9, the catch tank 920 extends radially outward from the axial wall portion 9201 around the reduction mechanism 34 in the reduction mechanism housing chamber S21, and has an inlet 921 at a position capable of capturing oil scraped up by the rotation of the output gear 30. The catch tank 920 also has an outlet 922 at its lower part that opens into the differential gear housing chamber S22. In this case, the axial A2 end of the return passage 292 (the opening on the reduction mechanism housing chamber S21 side) may be provided near the outlet 922. This makes it possible to return the oil used to cool the coil end 13 in space S11 (see Figure 2) of the motor housing chamber S1 to the lower part of the differential gear housing chamber S22 (the oil reservoir in which the output gear 30 is immersed) relatively quickly via the lower part of the catch tank 920. The catch tank 920 may also be connected to the axial oil passage 15a of the rotor shaft 15, etc., to supply oil to the axial oil passage 15a of the rotor shaft 15. Furthermore, the lower part of the catch tank 920 refers to the portion below the vertical center of the catch tank 920, for example, the portion below the first shaft C1.

[0070] In Figure 9, the return passage 290 (schematically shown as a circle in Figure 9) has its A2 end open to the differential gear housing chamber S22 and its A1 end communicating with the output shaft housing chamber S3. The return passage 292 (schematically shown as a circle in Figure 9) has its axial A1 end communicating with the space S11 of the motor housing chamber S1 and its axial A2 end communicating with the lower part of the transmission mechanism housing chamber S2 (the lower part of the catch tank 920). An oil temperature sensor 98 (schematically shown as a circle in Figure 9) is provided at the lower part of the catch tank 920. In this case, the oil temperature sensor 98 is provided near the outlet 922 of the catch tank 920. This reduces the possibility that the oil temperature sensor 98 may be above the oil level depending on the vehicle's driving conditions, thereby improving the reliability of the sensor information from the oil temperature sensor 98.

[0071] The oil sloshed up by the rotation of the output gear 30 (see Figure 2) of the differential gear mechanism 5 is introduced from the transmission mechanism housing chamber S2 to the output shaft housing chamber S3. The oil then flows downward due to gravity, lubricating the bearing BR2 on the A1 side that supports the first output member 61, and is returned from the output shaft housing chamber S3 to the differential gear housing chamber S22 via the end of the return passage 290 located below the second shaft C2 (the end on the axial A2 side). This makes it possible to slosh the oil up again by the rotation of the output gear 30 of the differential gear mechanism 5.

[0072] Furthermore, the oil stirred up by the rotation of the output gear 30 of the differential gear mechanism 5 is introduced into the axial oil passage 15a of the rotor shaft 15 via the catch tank 920. Specifically, the catch tank 920 is provided with a communication port 75 at its top. The communication port 75 is the radially outer opening of the radial communication passage 74, and the radially inner end of the communication passage 74 is connected to the axial oil passage 16a of the input member 16. In this case, the oil stirred up by the rotation of the output gear 30 of the differential gear mechanism 5 enters the communication passage 74 from the communication port 75 of the catch tank 920, and is then supplied to the axial oil passage 15a of the rotor shaft 15 via the axial oil passage 16a. The oil supplied to the axial oil passage 15a is ejected from the ejection hole 15b to the coil end 13 of the rotating electric machine 1, as described above. This allows the coil end 13 to be efficiently cooled by the oil churned up by the rotation of the output gear 30 of the differential gear mechanism 5. The oil sprayed onto the coil end 13 in space S12 of the motor housing chamber S1 is returned from space S12 to the transmission mechanism housing chamber S2 via the end of the return passage 290 located below the second shaft C2 (the end on the axial A2 side). Similarly, the oil sprayed onto the coil end 13 in space S11 of the motor housing chamber S1 is returned from space S11 to the transmission mechanism housing chamber S2 via the end of the return passage 292 located below the second shaft C2 (the end on the axial A2 side). The oil returned to the transmission mechanism housing chamber S2 in this way is returned to the differential gear housing chamber S22 from the outlet 922 in the catch tank 920 located below the second shaft C2. This makes it possible to churn it up again by the rotation of the output gear 30 of the differential gear mechanism 5.

[0073] In this embodiment, the catch tank 920 is formed in such a manner that it overlaps the fastening portion 500 when viewed in the axial direction A2. In Figure 9, the fastening portion 500, which is not visible in the same view when viewed from the X2 side, is schematically shown by dashed lines in perspective. In the example shown in Figure 9, the catch tank 920 overlaps the two upper and lower fastening portions 500 on the X1 side when viewed in the axial direction A2, but it may also overlap only one of the two fastening portions 500 (for example, the upper fastening portion 500). Also, in the example shown in Figure 9, the catch tank 920 overlaps substantially the entire upper fastening portion 500 on the X1 side when viewed in the axial direction A2, but it may also overlap a part of the upper fastening portion 500 on the X1 side. Also, in the example shown in Figure 9, the catch tank 920 overlaps a part of the lower fastening portion 500 on the X1 side when viewed in the axial direction A2, but it may also overlap substantially the entire lower fastening portion 500 on the X1 side.

[0074] This positional relationship between the catch tank 920 and the fastening portion 500 allows for effective utilization of the dead space created by the shape of the reduction gear housing chamber S21. Specifically, in the motor housing chamber S1, the area inside the outer boundary of the case 2's dimensions determined by the catch tank 920 (the outer boundary when viewed in the axial direction A2) becomes usable space (dead space) without increasing the dimensions of the case 2. Therefore, by positioning the fastening portion 500 in a position that overlaps with the catch tank 920 when viewed in the axial direction, this dead space can be effectively utilized. This prevents an increase in the dimensions of the case 2 caused by the fastening portion 500 (especially an increase in dimensions on the X1 side, or on the Y1 or Y2 side).

[0075] Although each embodiment has been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above. [Explanation of symbols]

[0076] 100...Vehicle drive unit, 1...Rotating electric machine, 2...Case, 90...Flow path forming member, 300...Refrigerant flow path, 34...Reduction mechanism (transmission mechanism), 5...Differential gear mechanism (transmission mechanism), 61...First output member (shaft member), 500...Fastening part (first fastening part, second fastening part), 802...Wiring connector, 600...Rectangle, CN1~CN4...Corner part, C1...First shaft (axis of the rotating electric machine), C2...Second shaft (axis of the shaft member), W...Wheel

Claims

1. Rotating electric machines and, A case for housing the aforementioned rotating electric machine, The rotating electric machine is equipped with a flow path forming member that is positioned between the outer circumferential surface and the inner circumferential surface of the case and forms a refrigerant flow path through which the refrigerant passes. The flow path forming member has a cylindrical shape and is fastened to the case at one end in the axial direction. A vehicle drive device in which, assuming a rectangle that circumscribes the outer shape of the rotating electric machine when viewed in the axial direction and has two sides parallel in the vertical direction, the fastening portion of the flow path forming member to the case includes, when viewed in the axial direction, a fastening portion that overlaps with at least one of the four corners of the rectangle and a fastening portion that does not overlap with the corner.

2. The machine further comprises a connector for wiring electronic components provided in connection with the aforementioned rotating electric machine, The vehicle drive device according to claim 1, wherein the wiring connector overlaps with at least one corner when viewed in the axial direction.

3. The transmission mechanism further comprises a mechanism that transmits the driving force from the rotating electric machine to the wheel via a shaft member, The axis of the shaft member is parallel to the axis of the rotating electric machine and offset to one side in one direction intersecting the axial direction. The vehicle drive device according to claim 1 or 2, wherein the at least one corner includes an upper corner and the other corner in the same direction.

4. The fastening portion is provided in three or more locations. The vehicle drive device according to claim 3, wherein two of the three or more fastening portions are located on the other side of the four corners in one direction.

5. The case further houses the transmission mechanism and has a catch tank for capturing the oil that is scooped up by the rotation of the gears of the transmission mechanism. The vehicle drive device according to claim 3, wherein the catch tank overlaps with at least one corner when viewed in the axial direction.

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