Motor unit

Abstract

To achieve low cost by cooling a motor from the inside and outside and also simplifying the construction of an oil passage.SOLUTION: A motor unit comprises: a motor 2; a housing 6 in which a housing space 80 accommodating the motor is provided; an oil O that is accumulated in a region on a vertically lower side of the housing space; and an oil path that guides the oil from the region on the vertically lower side of the housing space to a region on the vertically lower side of the housing space via the motor. The oil path includes: a first oil path 91 passing through the inside of the motor; and a second oil path 92 passing outside the motor. A cooler 97 for cooling oil is provided in either one of the first and second oil paths.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a motor unit.

Background Art

[0002] Patent Document 1 discloses a structure including a flow path that cools a motor by passing through the inside of a shaft and a flow path that cools the motor by supplying oil from above a stator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional structure, in addition to the two flow paths, a flow path that merges the two flow paths was provided, and a cooling device that cools the refrigerant was provided in the merged flow path. There was a risk that the configuration of the flow path would become complicated and the cost would increase.

[0005] In view of the above problems, one aspect of the present invention aims to provide a motor unit that cools a motor from the inside and the outside and simplifies the configuration of the oil path to achieve cost reduction.

Means for Solving the Problems

[0006] One aspect of the motor unit of the present invention is The device comprises a motor having a rotor that rotates around a motor shaft extending in the axial direction, a differential gear connected to the motor, a housing provided with a space for housing the motor and the differential gear, and an oil passage for supplying oil to the motor. The differential gear has a ring gear rotatable around a differential shaft parallel to the motor shaft. An electric pump is provided in the path of the oil passage, fixed to the outer surface of the housing. At least a portion of the motor is located to one side of the differential shaft and to the other side of at least a portion of the electric pump in directions perpendicular to both the axial and vertical directions. One embodiment of the motor unit of the present invention comprises a motor having a rotor that rotates about an axially extending motor shaft, a differential gear connected to the motor, a housing provided with a housing space for housing the motor and the differential gear, and an oil passage for supplying oil to the motor. The differential gear has a ring gear rotatable about a differential shaft parallel to the motor shaft. An electric pump is provided in the path of the oil passage. At least a portion of the motor is located to one side of the differential shaft and to the other side of at least a portion of the electric pump in directions perpendicular to both the axial and vertical directions. At least a portion of the ring gear and the motor overlap in the axial direction. One embodiment of the motor unit of the present invention comprises a motor having a rotor that rotates about an axially extending motor shaft, a differential gear connected to the motor, a housing provided with a housing space for housing the motor and the differential gear, and an oil passage for supplying oil to the motor. The differential gear has a ring gear rotatable about a differential shaft parallel to the motor shaft. An electric pump and a cooler for cooling the oil are provided in the path of the oil passage. At least a portion of the motor is located on one side of the differential shaft and on the other side of at least a portion of the electric pump in a direction perpendicular to both the axial and vertical directions. The oil passage has a second passage connecting the electric pump and the cooler, and a third passage connecting the cooler and the housing space. The housing has a wall portion surrounding the housing space. The second passage portion and the third passage portion are provided inside the wall portion.

Effects of the Invention

[0007] According to one aspect of the present invention, a motor unit is provided that cools the motor from both the inside and the outside, and simplifies the configuration of the oil passages to achieve cost reduction. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a conceptual diagram of a motor unit according to one embodiment. [Figure 2] Figure 2 is a perspective view of a motor unit according to one embodiment. [Figure 3] Figure 3 is a side view of a motor unit according to one embodiment. [Figure 4] Figure 4 is a cross-sectional view of the motor unit along the line IV-IV in Figure 3. [Figure 5] Figure 5 is a cross-sectional view of a rotor according to one embodiment. [Figure 6] Figure 6 is a plan view of the end plate. [Figure 7] Figure 7 is a cross-sectional view of the end plate along the line VII-VII in Figure 6. [Figure 8] Figure 8 is a cross-sectional view of the end plate of the first modified example. [Figure 9] Figure 9 is a plan view of the end plate of the second modified example. [Figure 10] Figure 10 is a cross-sectional view of a motor unit according to one embodiment, and shows the second oil passage. [Figure 11] Figure 11 is a perspective view of a motor unit in one embodiment, with a portion of the housing omitted. [Figure 12] Figure 12 is a plan view of the second reservoir of one embodiment. [Figure 13] Figure 13 is a perspective view of the second reservoir in a modified example. [Figure 14] Figure 14 is a cross-sectional view of a motor unit according to one embodiment, and shows a schematic diagram of the sub-reservoir. [Figure 15] Figure 15 is a front view of a partition wall opening in one embodiment. [Figure 16]FIG. 16 is a graph showing the relationship between the height of the oil level accumulating below the motor chamber in the motor unit of one embodiment and the area of the first region. [Figure 17] FIG. 17 is a front view of the partition opening of the modified example. [Figure 18] FIG. 18 is a graph showing the relationship between the height of the oil level accumulating below the motor chamber in the motor unit provided with the partition opening of the modified example and the area of the first region. [Figure 19] FIG. 19 is a side view showing the arrangement of each gear located inside the gear chamber in the motor unit of one embodiment. [Figure 20] FIG. 20 is a plan view of a parking mechanism that can be adopted in the motor unit of one embodiment. [Figure 21] FIG. 21 is a partial cross-sectional view showing the separation mechanism of the motor unit of Modified Example 1. [Figure 22] FIG. 22 is a conceptual diagram showing a state where the motor and the speed reducer are connected by the separation mechanism. [Figure 23] FIG. 23 is a conceptual diagram showing a state where the motor and the speed reducer are separated by the separation mechanism.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the motor according to the embodiment of the present invention will be described with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments and can be arbitrarily changed within the scope of the technical idea of the present invention. In the following drawings, in order to make each configuration easier to understand, the actual structure, the scale, the number, etc. in each structure may be made different.

[0010] In the following explanation, the direction of gravity is defined and explained based on the positional relationship when motor unit 1 is mounted on a vehicle located on a horizontal road surface. In the drawings, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system where appropriate. In the XYZ coordinate system, the Z axis direction represents the vertical direction (i.e., up and down direction), with the +Z direction being the upper side (opposite to the direction of gravity) and the -Z direction being the lower side (direction of gravity). The X axis direction is perpendicular to the Z axis direction and represents the front-to-rear direction of the vehicle on which motor unit 1 is mounted, with the +X direction being the front of the vehicle and the -X direction being the rear of the vehicle. However, it is also possible for the +X direction to be the rear of the vehicle and the -X direction to be the front of the vehicle. The Y axis direction is perpendicular to both the X axis direction and the Z axis direction and represents the width direction (left-to-right direction) of the vehicle.

[0011] In the following explanation, unless otherwise specified, the direction parallel to the motor shaft J2 of motor 2 (the Z-axis direction) will simply be referred to as the "axial direction," the radial direction centered on the motor shaft J2 will simply be referred to as the "radial direction," and the circumferential direction centered on the motor shaft J2, i.e., the direction around the axis of the motor shaft J2, will simply be referred to as the "circumferential direction." Furthermore, in the following explanation, "plan view" means the view from the axial direction. However, the above "parallel direction" also includes approximately parallel directions. Also, the above "orthogonal direction" also includes approximately orthogonal directions.

[0012] The following describes a motor unit (electric drive device) 1 according to an exemplary embodiment of the present invention, based on the drawings. Figure 1 is a conceptual diagram of the motor unit 1 according to one embodiment. Figure 2 is a perspective view of the motor unit 1. Figure 3 is a side view of the motor unit 1. Figure 4 is a cross-sectional view of the motor unit 1 along the line IV-IV in Figure 3. Note that some of the internal structure of the differential gear 5 is omitted in Figure 4.

[0013] Motor unit 1 is installed in vehicles that use an electric motor as a power source, such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHVs), and electric vehicles (EVs), and is used as the power source for those vehicles.

[0014] As shown in Figure 1, the motor unit 1 comprises a motor (main motor) 2, a reduction gear 4, a differential gear 5, a housing 6, oil O, and an oil passage 90 for supplying oil O to the motor 2. The motor unit 1 may also have a parking mechanism 7, as shown by dashed lines in Figure 2.

[0015] As shown in Figure 1, the motor 2 comprises a rotor 20 that rotates around a horizontally extending motor shaft J2, and a stator 30 located radially outward from the rotor 20. The reduction gear 4 is connected to the rotor 20 of the motor 2. The differential gear 5 is connected to the motor 2 via the reduction gear 4. The inside of the housing 6 is provided with a housing space 80 that accommodates the motor 2, the reduction gear 4, and the differential gear 5. Oil O is used to lubricate the reduction gear 4 and the differential gear 5, and also to cool the motor 2. The oil O accumulates in the vertically lower region of the housing space 80. Since the oil O functions as both a lubricant and a coolant, it is preferable to use an oil equivalent to a low-viscosity automatic transmission fluid (ATF). The oil passage 90 is a path for supplying oil O to the motor 2 from the lower region of the housing space 80. The oil passage 90 has a first oil passage 91 and a second oil passage 92.

[0016] In this specification, "oil passage" refers to the path of oil O circulating within the containment space 80. Therefore, "oil passage" is a concept that includes not only "flow channels" that form a steady flow of oil in a constant direction, but also paths where oil is temporarily retained (e.g., reservoirs) and paths through which oil drips.

[0017] <Housing> The housing space 80 provided inside the housing 6 houses the motor 2, reduction gear 4, and differential gear 5. The housing 6 holds the motor 2, reduction gear 4, and differential gear 5 in the housing space 80. The housing 6 has a partition wall 61c. The housing space 80 of the housing 6 is divided into a motor room 81 and a gear room 82 by the partition wall 61c. The motor 2 is housed in the motor room 81. The reduction gear 4 and differential gear 5 are housed in the gear room 82.

[0018] An oil reservoir P is provided in the lower region of the housing space 80, where oil O accumulates. In this embodiment, the bottom 81a of the motor chamber 81 is located above the bottom 82a of the gear chamber 82. A partition wall opening 68 is provided in the lower region of the partition wall 61c that separates the motor chamber 81 and the gear chamber 82. The partition wall opening 68 connects the motor chamber 81 and the gear chamber 82. The partition wall opening 68 moves the oil O accumulated in the lower region of the motor chamber 81 to the gear chamber 82. Therefore, in this embodiment, the oil reservoir P is provided in the lower region of the gear chamber 82.

[0019] A portion of the differential gear 5 is submerged in the oil reservoir P. The oil O accumulated in the oil reservoir P is stirred up by the operation of the differential gear 5, with some being supplied to the first oil passage 91 and some being diffused into the gear chamber 82. The oil O diffused into the gear chamber 82 is supplied to each gear of the reduction gear 4 and differential gear 5 within the gear chamber 82, spreading the oil O over the gear teeth. The oil O used by the reduction gear 4 and differential gear 5 drips down and is collected in the oil reservoir P located below the gear chamber 82. The capacity of the oil reservoir P in the containment space 80 is set so that when the motor unit 1 is stopped, a portion of the bearings of the differential gear 5 is submerged in the oil O.

[0020] The housing 6 is made of, for example, die-cast aluminum. The housing 6 constitutes the outer frame of the motor unit 1. The housing 6 has a motor housing section 61, a gear housing section 62, and a closing section 63. The gear housing section 62 is located to the left of the motor housing section 61. The closing section 63 is located to the right of the motor housing section 61.

[0021] The motor housing 61 has a cylindrical peripheral wall portion 61a that surrounds the motor 2 from the radially outer side, and a side plate portion 61b located on one axial side of the peripheral wall portion 61a. The space inside the peripheral wall portion 61a constitutes the motor chamber 81. The side plate portion 61b has a partition wall 61c and a protruding plate portion 61d. The partition wall 61c covers the opening on one axial side of the peripheral wall portion 61a. In addition to the partition wall opening 68 described above, the partition wall 61c is provided with an insertion hole 61f through which the shaft 21 of the motor 2 is inserted. The side plate portion 61b has a partition wall 61c and a protruding plate portion 61d that protrudes radially outward from the peripheral wall portion 61a. The protruding plate portion 61d is provided with a first axle passage hole 61e through which a drive shaft (not shown) that supports the wheel passes.

[0022] The closing portion 63 is fixed to the motor housing portion 61. The closing portion 63 closes the opening on the opposite side of the axial direction of the peripheral wall portion 61a. That is, the closing portion 63 closes the opening of the cylindrical motor housing portion 61. The closing portion 63 has a closing portion body 63a and a cover member 63b. The closing portion body 63a has a cylindrical projection 63d that protrudes into the housing space 80 located inside the motor housing portion 61. The projection 63d extends along the inner circumferential surface of the peripheral wall portion 61a. The closing portion body 63a is also provided with a window portion 63c that penetrates in the axial direction. The cover member 63b closes the window portion 63c from the outside of the housing space 80.

[0023] The gear housing 62 is fixed to the side plate portion 61b of the motor housing 61. The gear housing 62 has a concave shape that opens towards the side plate portion 61b. The opening of the gear housing 62 is covered by the side plate portion 61b. The space between the gear housing 62 and the side plate portion 61b constitutes a gear chamber 82 that houses the reduction gear 4 and the differential gear 5. The gear housing 62 is provided with a second axle passage hole 62e. The second axle passage hole 62e overlaps with the first axle passage hole 61e when viewed from the axial direction.

[0024] As shown in Figure 3, the gear housing 62 has a first reservoir 93 and a shaft supply passage 94. The first reservoir 93 is located on the axial side of the gear housing 62 facing the gear chamber 82 and extends along the axial direction. The first reservoir 93 receives oil O scooped up by the differential gear 5. The shaft supply passage 94 extends from the bottom of the first reservoir 93 toward the shaft 21 of the motor 2. The shaft supply passage 94 is a passage that supplies the oil O received in the first reservoir 93 to the inside of the hollow portion 22 of the shaft 21.

[0025] <Reduction Gear> As shown in Figure 4, the reduction gear 4 has the function of reducing the rotational speed of the motor 2 and increasing the torque output from the motor 2 according to the reduction ratio. The reduction gear 4 transmits the torque output from the motor 2 to the differential gear 5.

[0026] The reduction gear 4 includes a first gear (intermediate drive gear) 41, a second gear (intermediate gear) 42, a third gear (final drive gear) 43, and an intermediate shaft 45. The torque output from the motor 2 is transmitted to the ring gear (gear) 51 of the differential gear 5 via the motor 2's shaft 21, the first gear 41, the second gear 42, the intermediate shaft 45, and the third gear 43. The gear ratio and number of gears can be changed in various ways depending on the required reduction ratio. The reduction gear 4 is a parallel-axis gear type reduction gear in which the axes of each gear are arranged in parallel.

[0027] The first gear 41 is mounted on the outer circumferential surface of the shaft 21 of the motor 2. The first gear 41 rotates together with the shaft 21 around the motor shaft J2.

[0028] The intermediate shaft 45 extends along the intermediate shaft J4, which is parallel to the motor shaft J2. The intermediate shaft 45 has a cylindrical shape centered on the intermediate shaft J4. The intermediate shaft 45 rotates about the intermediate shaft J4. The intermediate shaft 45 is rotatably supported by a pair of intermediate shaft holding bearings 87. One of the pair of intermediate shaft holding bearings 87 is held on the surface of the partition wall 61c facing the gear chamber 82. The other of the pair of intermediate shaft holding bearings 87 is held in the gear housing 62.

[0029] The second gear 42 and the third gear 43 are provided on the outer circumferential surface of the intermediate shaft 45. The second gear 42 and the third gear 43 are connected via the intermediate shaft 45. The second gear 42 and the third gear 43 rotate about the intermediate shaft J4. The second gear 42 meshes with the first gear 41. The third gear 43 meshes with the ring gear 51 of the differential 5. The third gear 43 is located on the partition wall 61c side relative to the second gear 42. In this embodiment, the intermediate shaft 45 and the third gear 43 are a single component.

[0030] <Differential Gear> The differential gear 5 is a device for transmitting torque output from the motor 2 to the wheels of the vehicle. The differential gear 5 has the function of absorbing the speed difference between the left and right wheels when the vehicle turns, and transmitting the same torque to the axles 55 of both the left and right wheels. The differential gear 5 includes a ring gear 51, a gear housing 57, a pair of pinion gears (not shown), a pinion shaft (not shown), and a pair of side gears (not shown).

[0031] The ring gear 51 rotates around a differential shaft J5 that is parallel to the motor shaft J2. Torque output from the motor 2 is transmitted to the ring gear 51 via the reduction gear 4. In other words, the ring gear 51 is connected to the motor 2 via other gears. The ring gear 51 is fixed to the outer circumference of the gear housing 57.

[0032] The gear housing 57 houses a pair of pinion gears and a pair of side gears. When torque is transmitted to the ring gear 51, the gear housing 57 rotates together with the ring gear 51 around the differential shaft J5. The pair of pinion gears are bevel gears facing each other. The pair of pinion gears are supported by the pinion shaft. The pair of side gears are bevel gears that mesh perpendicularly with the pair of pinion gears. Each of the pair of side gears has a mating section. An axle is fitted into each mating section. The pair of axles, fitted into different mating sections, rotate around the differential shaft J5 with the same torque.

[0033] <Motor> As shown in Figure 4, motor 2 is an inner rotor type motor comprising a stator 30 and a rotor 20 rotatably arranged inside the stator 30. The rotor 20 rotates when power is supplied to the stator 30 from a battery (not shown). The torque of motor 2 is transmitted to the differential gear 5 via the reduction gear 4.

[0034] (Stator) The stator 30 includes a stator core 32, a coil 31, and an insulator (not shown) interposed between the stator core 32 and the coil 31. The stator 30 is held in the housing 6.

[0035] The stator core 32 has a plurality of magnetic pole teeth (not shown) extending radially inward from the inner circumferential surface of the annular yoke. In this embodiment, the stator core 32 has 48 slots formed between the magnetic pole teeth. A coil 31 is formed by wrapping a coil wire between the magnetic pole teeth.

[0036] The coil 31 has a coil end 31a that protrudes from the axial end face of the stator core 32. That is, the stator 30 has a coil end 31a. The coil end 31a protrudes axially beyond the end of the rotor core 24 of the rotor 20. The coil end 31a protrudes axially on both sides relative to the rotor core 24.

[0037] (Rotor) The rotor 20 includes a shaft (motor shaft) 21, a rotor core 24, a rotor magnet (permanent magnet) 25, a pair of plate-shaped end plates 26, a nut 29, and a washer (cover) 28.

[0038] (Shaft) The shaft 21 extends from a motor shaft J2 that extends horizontally and in the width direction of the vehicle (perpendicular to the direction of travel of the vehicle). The shaft 21 has a first shaft portion 21A and a second shaft portion 21B that are connected to each other on the same axis.

[0039] The shaft 21 is a hollow shaft provided with a hollow portion 22 having an inner circumferential surface extending along the motor shaft J2. The hollow portion 22 includes a first hollow portion 22A located inside the first shaft portion 21A and a second hollow portion 22B located inside the second shaft portion 21B. The first hollow portion 22A and the second hollow portion 22B are aligned along the axial direction and communicate with each other.

[0040] The first shaft portion 21A is positioned in the motor chamber 81 of the housing space 80. The first shaft portion 21A is located radially inward of the stator 30 and penetrates the rotor core 24 along the motor shaft J2. The first shaft portion 21A has a first end 21e located on the output side (i.e., the reduction gear 4 side) and a second end 21f located on the opposite side.

[0041] The first shaft portion 21A is rotatably supported by a pair of first bearings 89. The pair of first bearings 89 support the first end 21e and the second end 21f of the first shaft portion 21A. One of the pair of first bearings 89 is held in the closing portion 63. The other of the pair of first bearings 89 is held in the surface of the partition wall 61c facing the motor chamber 81.

[0042] Figure 5 is a cross-sectional view of the rotor 20. In Figure 5, the second shaft portion 21B is shown by dashed lines. The first shaft portion 21A is provided with a pair of communication holes 23. The communication holes 23 extend radially and connect the outside of the shaft 21 to the hollow portion 22. That is, the shaft 21 is provided with a pair of communication holes 23. The pair of communication holes 23 are aligned along the axial direction. In this specification, a single communication hole 23 is defined as a hole that extends from the outer circumferential surface of the shaft 21, through the hollow portion, and back to the outer circumferential surface.

[0043] The outer circumferential surface of the first shaft portion 21A is provided with a flange portion (cover portion) 21c and a threaded portion 21d, which are aligned along the axial direction. That is, the outer circumferential surface of the shaft 21 is provided with a flange portion 21c and a threaded portion 21d. The rotor core 24 is located between the flange portion 21c and the threaded portion 21d in the axial direction. A nut 29 is fastened to the threaded portion 21d.

[0044] As shown in Figure 4, the second shaft portion 21B is located coaxially with the first shaft portion 21A. The second shaft portion 21b has a third end portion 21g located on the side of the first shaft portion 21A and a fourth end portion 21h located on the opposite side. The second shaft portion 21B is connected to the first end portion 21e of the first shaft portion 21A at the third end portion 21g.

[0045] The second shaft portion 21B is positioned in the gear chamber 82 of the housing space 80. The third end portion 21g of the second shaft portion 21B protrudes towards the motor chamber 81 through an insertion hole 61f provided in the partition wall 61c and is connected to the first shaft portion 21A. A first gear 41 is provided on the outer circumferential surface of the second shaft portion 21B. The first gear 41 is part of the reduction gear 4. The first gear 41 meshes with the second gear 42 and transmits the output of the shaft 21 to the second gear.

[0046] The second shaft portion 21B is rotatably supported by a pair of second bearings 88. One of the pair of second bearings 88 is held on the surface of the partition wall 61c facing the gear chamber 82. The other of the pair of second bearings 88 is held in the gear housing portion 62.

[0047] The hollow section 22 opens axially at the second end 21f of the first shaft section 21A and the fourth end 21h of the second shaft section 21B. Oil O is supplied to the hollow section 22 from the opening at the fourth end 21h. The oil O supplied to the hollow section 22 flows from the fourth end 21h side towards the second end 21f side. The oil O supplied to the hollow section 22 flows out to the outside of the shaft 21 through the communication hole 23. In the following description, the fourth end 21h side may be referred to as the upstream side in the flow direction of the hollow section 22, and the second end 21f side may be referred to as the downstream side in the flow direction of the hollow section 22.

[0048] As shown in Figure 5, the first hollow section 22A has a first region 22p, a second region (small diameter hollow section) 22q, and a third region (large diameter hollow section) 22r, each with a different inner diameter. The inner diameters of the first region 22p, the second region 22q, and the third region 22r increase in this order. That is, the second region 22q has a larger inner diameter than the first region 22p, and the third region 22r has a larger inner diameter than both the first region 22p and the third region 22r. The first region 22p, the second region 22q, and the third region 22r are arranged in this order from the downstream side to the upstream side in the flow direction. The first region 22p is located on the second end 21f side. The second region 22q is located between the first region 22p and the third region 22r in the axial direction. The third region 22r is located on the first end 21e side. In other words, the third region 22r is located on the second shaft portion 21B side of the second region 22q.

[0049] In the third region 22r, one of the pair of communication holes 23, the one on the upstream side in the flow direction, is open. In the second region 22q, the other of the pair of communication holes 23, the one on the downstream side in the flow direction, is open.

[0050] Furthermore, the inner circumferential surface of the first hollow portion 22A has a first stepped surface 22s located between the first region 22p and the second region 22q, and a second stepped surface (stepped surface) 22t located between the second region 22q and the third region 22r. The first stepped surface 22s and the second stepped surface 22t face the second shaft portion 21B side. In addition, the first stepped surface 22s and the second stepped surface 22t are inclined toward the upstream side in the flow direction as they extend radially outward.

[0051] The third end portion 21g of the second shaft portion 21B is inserted into the third region 22r of the first shaft portion 21A. A female spline 22e is provided in the third region 22r. On the other hand, a male spline 22g is provided on the outer circumferential surface of the third end portion 21g of the second shaft portion 21B. The female spline 22e and the male spline 22g fit together. This connects the first shaft portion 21A and the second shaft portion 21B.

[0052] A gap is provided between the end face of the second shaft portion 21B facing the first shaft portion 21A (i.e., the end face of the third end portion 21g) and the second stepped surface 22t. The gap between the end face of the third end portion 21g and the second stepped surface 22t forms a groove 22u on the inner circumferential surface of the hollow portion 22. That is, a groove 22u extending in the circumferential direction is provided on the inner circumferential surface of the hollow portion 22, and the groove 22u is composed of the end face of the third end portion 21g of the second shaft portion 21B, the inner circumferential surface of the third region 22r, and the second stepped surface 22t.

[0053] Of the pair of communication holes 23, one communication hole 23 located upstream in the flow direction of the oil O opens into the hollow portion 22 in the groove 22u. Centrifugal force is applied to the oil O supplied into the hollow portion 22 as the shaft 21 rotates. Since a groove 22u is provided on the inner circumferential surface of the hollow portion 22, the oil O accumulates in the groove 22u due to the centrifugal force. According to this embodiment, since the communication hole 23 opens into the groove 22u, the oil O accumulated in the groove 22u can be efficiently guided into the communication hole 23.

[0054] According to this embodiment, the gap at the connection point between the first shaft portion 21A and the second shaft portion 21B can be used as a groove 22u to store oil O. Therefore, there is no need to perform any special processing to provide the groove 22u for storing oil O.

[0055] When multiple communication holes 23 are arranged along the axial direction, oil O tends to flow more easily into the communication holes 23 located downstream in the flow direction of oil O, and there may be insufficient oil O flowing into the communication holes 23 located upstream in the flow direction of oil O. According to this embodiment, since the communication holes 23 located upstream in the flow direction open in the groove 22u, sufficient oil O can flow into the communication holes 23 located upstream in the flow direction.

[0056] According to this embodiment, the diameter of the hollow section 22 decreases in stages as you move from the upstream side to the downstream side in the flow direction. This makes it easier for the oil O to spread from the upstream side to the downstream side of the hollow section 22. In addition, one of the pair of communication holes 23 opens to the third region 22r, and the other on the downstream side opens to the second region 22q. That is, the opening of the downstream communication hole 23 is located in a region where the diameter of the hollow section 22 is smaller compared to the opening of the upstream communication hole 23. Therefore, sufficient oil O can flow into the communication hole 23 located on the downstream side.

[0057] A portion of the female spline 22e is located in the gap between the end face of the third end 21g and the second stepped surface 22t. Therefore, the inner circumferential surface of the hollow section 22 is provided with convex and concave portions aligned along the circumferential direction, originating from the female spline 22e. If the cross-sectional shape of the hollow section is circular with the motor shaft as the center, even if the shaft rotates, the oil O inside the hollow section may spin freely relative to the shaft, and centrifugal force may not be applied to the oil O. In contrast, by providing convex and concave portions aligned along the circumferential direction inside the hollow section 22, the oil O can be rotated in conjunction with the rotation of the shaft 21, thereby applying centrifugal force to the oil O in the hollow section 22. This allows the oil O to be smoothly guided into the communication hole 23.

[0058] According to this embodiment, splines (male spline 22g and female spline 22e) that spline-fit each other are provided on the outer circumferential surface of the second shaft portion 21B and the inner circumferential surface of the third region 22r. Furthermore, a portion of the splines (female spline 22e) of the third region 22r is located within the groove 22u. Therefore, centrifugal force can be applied to the oil O in the hollow portion 22 by utilizing the female spline 22e used for fitting. In other words, there is no need to process the inner circumferential surface of the hollow portion 22 to create an uneven shape in order to apply centrifugal force to the oil O.

[0059] (Rotor Core) The rotor core 24 is constructed by laminating silicon steel sheets. The rotor core 24 is a cylindrical body extending along the axial direction. The rotor core 24 has a pair of axial end faces 24a facing opposite directions in the axial direction, and an outer peripheral surface 24b facing radially outward.

[0060] The rotor core 24, along with a pair of end plates 26, is sandwiched between the nut 29 and the flange portion 21c. A washer 28 is interposed between the nut 29 and the end plate 26.

[0061] The rotor core 24 is provided with one fitting hole 24c located in the center when viewed from the axial direction and penetrating along the axial direction, a plurality of magnet holding holes 24d, and a plurality of core through holes 24e. The fitting hole 24c, magnet holding holes 24d, and core through holes 24e open to a pair of axial end faces 24a.

[0062] The fitting hole 24c is circular with the motor shaft J2 as its center. The shaft 21 is inserted through and fitted into the fitting hole 24c. Therefore, the rotor core 24 surrounds the shaft 21 from the radially outer side. The fitting between the shaft 21 and the fitting hole 24c is a clearance fit. Therefore, deformation of the rotor core 24 due to the fitting of the shaft 21 is suppressed. A projection (not shown) is provided on the inner circumferential surface of the fitting hole 24c that protrudes radially inward. This projection fits into a keyway (not shown) provided on the outer circumferential surface of the shaft 21. This suppresses relative rotation between the rotor core 24 and the shaft 21.

[0063] Multiple core through-holes 24e are arranged in a line along the circumferential direction. The core through-holes 24e are located radially inward from the magnet holding holes 24d. The core through-holes 24e serve to facilitate the flow of oil O between a pair of axial end faces 24a.

[0064] Multiple magnet holding holes 24d are arranged in a line along the circumferential direction. Rotor magnets 25 are inserted into the magnet holding holes 24d. The magnet holding holes 24d hold the rotor magnets 25. In other words, the rotor 20 of this embodiment is an embedded type (IPM (interior permanent magnet)) in which the rotor magnets 25 are embedded inside the rotor core 24.

[0065] The rotor magnets 25 are permanent magnets. Multiple rotor magnets 25 are inserted into multiple magnet holding holes 24d arranged in the circumferential direction and fixed to the rotor core 24. The multiple rotor magnets 25 are arranged along the circumferential direction.

[0066] (End Plate) Figure 6 is a plan view of the end plate 26. Figure 7 is a cross-sectional view of the end plate 26 along the line VII-VII in Figure 6. In Figures 6 and 7, other components of the motor unit 1 are shown by dashed lines.

[0067] As shown in Figure 6, the end plate 26 is circular in plan view. The end plate 26 is a metal plate. The end plate 26 is provided with a circular central hole 26i that penetrates along the axial direction. A key portion 26q is provided on the inner circumferential surface of the central hole 26i. The key portion 26q fits into a keyway 21k provided on the shaft 21. Relative rotation between the end plate 26 and the shaft 21 is suppressed by the fitting of the key portion 26q and the keyway 21k.

[0068] As shown in Figure 5, the end plate 26 has a first surface 26a and a second surface 26b. The first surface 26a faces the axial end surface 24a of the rotor core 24. The second surface 26b faces the opposite side from the first surface 26a.

[0069] The pair of end plates 26 are located on opposite sides of the rotor core 24 in the axial direction. The pair of end plates 26 contact the pair of axial end faces 24a of the rotor core 24. One of the pair of end plates 26 (the first end plate 26A) is located between one axial end face 24a of the rotor core 24 and the flange 21c. The other of the pair of end plates 26 (the second end plate 26B) is located between the other axial end face 24a of the rotor core 24 and the washer 28. The end plate 26 contacts the axial end face 24a on its first surface 26a. The end plate 26 also contacts the flange 21c or the washer 28 on its second surface 26b.

[0070] According to this embodiment, the rotor core 24 and the pair of end plates 26 are sandwiched between the flange portion 21c and the nut 29. As a result, the pair of end plates 26 are pressed against the axial end faces 24a of the rotor core 24 from both axial sides. A frictional force is generated at the contact point between the first surface 26a of the end plate 26 and the axial end face 24a of the rotor core 24, thereby suppressing relative rotation between the rotor core 24 and the shaft 21. When the rotor core and shaft are fixed by press-fitting, the rotor core deforms, changing the magnetic path passing through the rotor core and increasing iron loss. In particular, in motors for vehicle drive, as in this embodiment, the driving force is large, so it is necessary to ensure a large tightening allowance for press-fitting, which tends to increase iron loss of the rotor core. According to this embodiment, the rotor core 24 is fixed to the shaft 21 via the end plates 26. Therefore, the fitting between the fitting hole 24c of the rotor core 24 and the shaft 21 can be a clearance fit, which suppresses deformation of the rotor core 24 and provides a highly efficient motor 2.

[0071] As shown in Figure 7, the first surface 26a is provided with a recess 26f and an inclined surface 26e that surrounds the recess 26f from the radially outer side. The recess 26f is circular in plan view with the motor shaft J2 as the center. The recess 26f has a recess bottom surface 26g and a recess inner circumferential surface 26h. The recess bottom surface 26g is a plane perpendicular to the motor shaft J2. The recess inner circumferential surface 26h is located between the recess bottom surface 26g and the inclined surface 26e. The recess inner circumferential surface 26h is inclined in a direction that makes the recess 26f shallower as it moves from the radially inner side to the radially outer side. A gap is provided between the recess 26f and the axial end surface 24a of the rotor core 24. Oil O accumulates in this gap and cools the axial end surface 24a of the rotor core 24.

[0072] The inclined surface 26e is provided in the region that is radially outermost on the first surface 26a and extends along the circumferential direction. The inclined surface 26e is inclined toward the rotor core 24 side by an inclination angle θ as it extends radially outward. Here, the inclination angle θ is the angle between the plane perpendicular to the motor shaft J2 and the inclined surface 26e.

[0073] The end plate 26 contacts the axial end face 24a of the rotor core 24 at the inclined surface 26e of the first surface 26a. As the inclined surface 26e is directed radially outward, it is directed toward the rotor core 24, and therefore contacts the axial end face 24a in its outermost radial region. This allows the frictional force generated by the contact between the inclined surface 26e and the axial end face 24a to be directed as far radially outward as possible. Furthermore, the perpendicular stress between the inclined surface 26e and the axial end face 24a can be increased radially outward. This allows the limit value of the static friction force to be increased radially outward. The holding torque that suppresses the relative rotation between the end plate 26 and the rotor core 24 is proportional to the distance from the axis of rotation and the frictional force. Therefore, according to this embodiment, the holding torque that suppresses the relative rotation between the end plate 26 and the rotor core 24 can be increased, and the rotor core 24 can be firmly held by the end plate 26. To achieve this effect, it is preferable that the inclination angle θ of the inclined surface 26e be between 0.1° and 5°.

[0074] Furthermore, in this embodiment, the end plate 26 contacts the axial end face 24a of the rotor core 24 at its inclined surface 26e. This stabilizes the contact position between the end plate 26 and the rotor core 24. Consequently, variations in the transmitted torque between the end plate 26 and the rotor core 24 can be suppressed, and the rotor core 24 can be securely fixed to the shaft 21.

[0075] Furthermore, according to this embodiment, by providing an inclined surface 26e on the end plate 26, reliable contact can be ensured even if there are variations in the flatness of the contact area between the end plate 26 and the axial end face 24a of the rotor core 24. As will be explained later, an oil passage 26t (see Figure 5) is provided on the radially inner side of the inclined surface 26e. Generally, when oil enters the space between the rotor core and the stator, the rotational efficiency of the rotor core decreases. By the inclined surface 26e contacting the axial end face 24a of the rotor core 24, the oil O in the oil passage 26t can be prevented from entering the gap between the outer circumferential surface 24b of the rotor core 24 and the stator 30 from between the end plate 26 and the rotor core 24. The inclined surface 26e may be configured such that the inclination angle changes as it extends radially outward. Alternatively, the inclined surface 26e may be a curved surface whose inclination angle changes as it extends radially outward.

[0076] As shown in Figure 5, the inclined surface 26e closes the opening of the magnet holding hole 24d of the rotor core 24. This prevents the rotor magnet 25, which is held inside the magnet holding hole 24d, from popping out of the opening of the magnet holding hole 24d. This prevents a part of the rotor magnet 25 from entering the drive part within the housing recess.

[0077] As shown in Figure 7, the second surface 26b is provided with a flat portion 26c and a chamfered portion 26d located on the outer edge of the flat portion 26c. The flat portion 26c is perpendicular to the motor shaft J2. The chamfered portion 26d is inclined toward the first surface 26a as it extends radially outward.

[0078] As shown in Figure 5, the end plate 26 is provided with two sets of plate through holes 26p, a first groove (first recess) 26j, and a second groove (second recess) 26k. Below, one set of the two sets of plate through holes 26p, first groove 26j, and second groove 26k will be described, but the other set has a similar configuration.

[0079] The plate through-hole 26p extends along the axial direction. The first groove 26j is located on the first surface 26a. The first groove 26j extends radially inward from the opening of the plate through-hole 26p. The first groove 26j opens radially inward on the inner circumferential surface of the central hole 26i. The second groove 26k is located on the second surface 26b. The second groove 26k extends radially outward from the opening of the plate through-hole 26p. The second groove 26k opens radially outward on the chamfered portion 26d.

[0080] The axially oriented opening of the first groove 26j of the end plate 26 is covered by the axial end face 24a of the rotor core 24. The radially oriented opening of the first groove 26j connects to the communication hole 23 of the shaft 21.

[0081] The oil O supplied to the hollow portion 22 of the shaft 21 flows radially outward through the communication hole 23. The oil O also flows into the first groove 26j from the radially outward opening of the communication hole 23. Furthermore, the oil O flows through the plate through hole 26p toward the first surface 26a and the second surface 26b, and is discharged to the outside of the rotor 20 through the second groove 26k. As shown in Figure 4, the coil end 31a of the stator 30 is provided on the radially outward side of the end plate 26. The oil O discharged to the outside of the rotor 20 is supplied to the coil end 31a to cool the coil end 31a.

[0082] The first groove 26j, the plate through hole 26p, and the second groove 26k of the end plate 26 function as oil passages 26t. That is, the oil passage 26t is composed of the first groove 26j, the plate through hole 26p, and the second groove 26k. Each of the pair of end plates 26 is provided with an oil passage 26t that communicates with the communication hole 23 and extends radially to open.

[0083] In this embodiment, the end plate 26 consists of a plate through hole 26p, a first groove 26j, and a second groove 26k, which constitute the oil passage 26t. Therefore, according to this embodiment, the oil passage 26t can be constructed using an inexpensive part (end plate 26) manufactured by mold molding.

[0084] The first grooves 26j of the pair of end plates 26 are connected to the core through-holes 24e. That is, the core through-holes 24e connect the first grooves 26j of the pair of end plates 26 to each other. In other words, the core through-holes 24e connect the oil passages 26t of the pair of end plates 26 to each other. Furthermore, at least a portion of the opening of the core through-hole is located radially outward from the plate through-holes 26p.

[0085] According to this embodiment, the core through-hole 24e connects the first grooves 26j of the pair of end plates 26, allowing a portion of the oil O passing through the first grooves 26j to flow into the core through-hole 24e. This allows the rotor core 24 to be cooled from the inside by the oil O in the core through-hole 24e. In addition, the rotor magnet 25 held by the rotor core 24 can be cooled via the rotor core 24.

[0086] According to this embodiment, the opening of the core through-hole 24e is located radially outward from the plate through-hole 26p of the pair of end plates 26. This allows oil O to accumulate inside the core through-hole 24e due to the centrifugal force of the rotor 20, and to be supplied from the core through-hole 24e to the first grooves 26j of the end plates 26 on both sides. Furthermore, if there is insufficient oil O in the first groove 26j of one of the pair of end plates 26, oil O can be supplied from the other side through the core through-hole 24e. Therefore, it becomes possible to release approximately the same amount of oil O from each end plate 26 to the coil end 31a, enabling stable cooling of the coil 31.

[0087] As shown in Figure 5, of the pair of end plates 26, the one sandwiched between the flange portion 21c and the rotor core 24 is designated as the first end plate 26A, and the other one sandwiched between the nut 29 and the rotor core 24 is designated as the second end plate 26B.

[0088] In the first end plate 26A, a portion of the radially inner side of the plate through hole 26p is covered by the flange portion 21c. Also, in the first end plate 26A, the axially oriented opening of the second groove 26k faces axially outward as a whole. In other words, in the first end plate 26A, the axially oriented opening of the second groove 26k is entirely exposed when viewed from the axial direction. That is, the second groove 26k of the first end plate 26A communicates with the outside at its axially oriented opening. In the first end plate 26A, the second groove 26k functions as a first open portion 26s, with a portion of the plate through hole 26p and the entire axially oriented opening freed from the washer 28. In the first end plate 26A, the oil O that has passed through the plate through hole 26p is discharged from the first open portion 26s.

[0089] A washer 28 is interposed between the second end plate 26B and the nut 29. In the second end plate 26B, the plate through hole 26p and a portion of the radially inner side of the axially oriented opening of the second groove 26k are covered by the washer 28. Of the axially oriented opening of the second groove 26k, the portion covered by the washer 28 is called the covered portion, and the portion not covered by the washer 28 is called the open portion. That is, in the second end plate 26B, the axially oriented opening of the second groove 26k has a covered portion covered by the washer 28 and a second open portion 26r not covered by the washer. The second groove 26k of the second end plate 26B faces axially outward at the second open portion 26r located at the radially outer end of the second groove 26k. In other words, the second groove 26k of the second end plate 26B is exposed at the second opening 26r when viewed from the axial direction. That is, the second groove 26k of the second end plate 26B is in communication with the outside at the second opening 26r. The second opening 26r is located at the radially outer end of the second groove 26k. In the second end plate 26B, the oil O that has passed through the plate through hole 26p is discharged from the second opening 26r.

[0090] According to the first end plate 26A and the second end plate 26B of this embodiment, the provision of a second groove 26k on the second surface 26b allows the oil O flowing to the second surface 26b side through the plate through hole 26p to be moved radially outward along the second groove 26k. Therefore, it becomes possible to stably supply the oil O to the second opening 26r, and to stably supply the oil O to the coil end 31a of the stator 30.

[0091] In this embodiment, the flange portion 21c or washer 28 of the first end plate 26A and the second end plate 26B each function as a cover portion that covers the axial opening of the second groove 26k. That is, the rotor 20 has a pair of cover portions (flange portion 21c and washer 28) located at the axial end of the rotor core 24 via the end plate 26. The cover portions (flange portion 21c and washer 28) cover the axial opening of the plate through hole 26p from the outside, thereby guiding the oil O flowing out from the plate through hole 26p towards the second surface 26b to flow along the second groove 26k. In this embodiment, the behavior of the oil O can be controlled by the cover portions (flange portion 21c and washer 28) to prevent the oil O from entering between the rotor core 24 and the stator 30.

[0092] According to the second end plate 26B of this embodiment, the axially oriented opening of the second groove 26k is partially covered by the washer 28 and faces axially outward at the second opening 26r. That is, in the region of the second groove 26k leading to the second opening 26r, the oil O does not overflow axially, and the oil O can be reliably moved to the second opening 26r. As a result, the oil O can be stably discharged from the second opening 26r and stably supplied to the coil end 31a.

[0093] According to this embodiment, the second groove 26k faces axially outward in the second opening 26r located at the radial end. Therefore, the oil O that has passed through the second groove 26k can be scattered axially from the second opening 26r. This allows the oil O to be scattered toward the coil end 31a which protrudes axially beyond the end of the rotor core 24, thereby effectively cooling the coil 31 at the coil end 31a.

[0094] In the first end plate 26A of this embodiment, the first opening 26s is provided over a part of the plate through hole 26p and the entire axially oriented opening. However, as shown by dashed lines in Figure 5, the flange portion 21c may cover a part of the axially oriented opening of the second groove 26k. In this case, the first opening 26s of the first end plate 26A is located at the radially outer end, similar to the second opening 26r of the second end plate 26B, and can achieve the same effect as the second opening 26r.

[0095] In this embodiment, the end plate 26 is provided with a groove-shaped first recess 26j and a second recess 26k. However, even if the recess is not groove-shaped, the above-mentioned effects can be achieved. By providing the first recess 26j and the second recess 26k that extend radially, the oil O can be smoothly guided along the radial direction.

[0096] (First Modified End Plate) Figure 8 is a cross-sectional view of an end plate 126 of a first modified form that can be used in this embodiment. Components of the same form as in the above-described embodiment will be described using the same reference numerals. The end plate 126 of the first modified form has a first surface 126a facing the rotor core 24 and a second surface 126b facing the opposite side of the first surface 126a, similar to the above-described embodiment. The end plate 126 is also provided with a pair of plate through holes 126p, a pair of first grooves 126j, and a pair of second grooves 126k. The plate through holes 126p extend in the axial direction. The first grooves 126j are located on the first surface 126a. The first grooves 126j extend radially inward from the plate through holes 126p. The second grooves 126k are located on the second surface 126b. The second groove 126k extends radially outward from the plate through hole 126p. The axially facing opening of the second groove 126k is partially covered by the cover portion 128, and the open portion 126r faces axially outward. Here, the cover portion 128 is a washer 28 or a flange portion 21c (see Figure 5).

[0097] In this modified example, the bottom of the second groove 126k is provided with an inclined surface 126u, the depth of which decreases as it extends radially outward. The inclined surface 126u overlaps with the open portion 126r when viewed from the axial direction. According to this modified example, by providing the inclined surface 126u in the second groove 126k, an axial component can be added to the flow of the oil O. The oil O can be scattered axially and effectively dispersed toward the coil end 31a that protrudes axially beyond the end of the rotor core 24.

[0098] (Second Modified End Plate) Figure 9 is a plan view of a second modified end plate 226 that can be used in this embodiment. Components that are the same as those in the above-described embodiment will be described using the same reference numerals. The end plate 226 of the second modified embodiment has a first surface 226a and a second surface 226b facing the opposite side of the first surface 226a, similar to the above-described embodiment. The end plate 226 also has a pair of plate through holes 226p, a pair of first grooves 226j and a pair of second grooves 226k. The plate through holes 226p extend in the axial direction. The first grooves 226j are located on the first surface 226a. The first grooves 226j extend radially inward from the plate through holes 226p. The second grooves 226k are located on the second surface 226b. The second groove 226k extends radially outward from the plate through hole 226p. The axially facing opening of the second groove 226k is partially covered by the cover portion 228, and the open portion 226r faces axially outward. Here, the cover portion 228 is a washer 28 or a flange portion 21c (see Figure 5).

[0099] The second groove 226k is a groove that extends along the radial direction. Furthermore, when viewed from the axial direction, the direction in which the second groove 226k extends is inclined with respect to the radial direction. In addition, the second groove 226k curves such that the angle of inclination with respect to the radial direction increases as it moves radially outward. According to this modified example, because the second groove 226k is inclined with respect to the radial direction, centrifugal force can be applied to the oil O passing through the second groove 226k from the inclined wall surface of the second groove 226k. This increases the velocity of the oil O scattered from the open section 226r, and ensures that the oil O hits the coil end 31a even when the distance to the coil end 31a is large.

[0100] In this modified example, the pair of second grooves 226k have different shapes when viewed from the axial direction. One of the pair of second grooves 226k, the second groove 226kA, is curved less in the axial direction and has a smaller angle of inclination with respect to the radial direction compared to the other second groove 226kB. In other words, according to this embodiment, the direction in which each groove of the multiple second grooves 226kA and 226kB extends when viewed from the axial direction has a different angle with respect to the radial direction. Therefore, the magnitude of the centrifugal force that the pair of second grooves 226kA and 226kB impart to the oil O is different from that of the other second groove 226kB. The oil O that is scattered from the other second groove 226kB travels at a higher speed and over a greater distance than the oil O that is scattered from the other second groove 226kA. In other words, according to this modified version, it becomes possible to scatter oil O to different regions in the multiple second grooves 226kA and 226kB, allowing oil O to be applied to a wide area of ​​the coil end 31a.

[0101] <Oil passage> As shown in Figure 1, the oil passage 90 is located inside the housing 6, i.e., in the housing space 80. The oil passage 90 spans the motor chamber 81 and the gear chamber 82 of the housing space 80. The oil passage 90 is a path for oil O that guides oil O from the oil reservoir P (i.e., the lower area of ​​the housing space 80) through the motor 2 and back to the oil reservoir P. The oil passage 90 has a first oil passage (oil passage) 91 that passes inside the motor 2 and a second oil passage (oil passage) 92 that passes outside the motor 2. The oil O cools the motor 2 from the inside and outside in the first oil passage 91 and the second oil passage 92. The oil passage 90 constitutes an oil cooling mechanism.

[0102] The first oil passage 91 and the second oil passage 92 are both paths that supply oil O from the oil reservoir P to the motor 2 and collect it back into the oil reservoir P. In the first oil passage 91 and the second oil passage 92, the oil O drips from the motor 2 and accumulates in the lower region of the motor chamber. The oil O accumulated in the lower region of the motor chamber 81 moves through the partition opening 68 to the lower region of the gear chamber 82 (i.e., the oil reservoir P).

[0103] A cooler 97 for cooling the oil O is provided in the path of the first oil passage 91. The oil O that has passed through the first oil passage 91 and been cooled by the cooler 97 merges with the oil O that has passed through the second oil passage 92 in the oil reservoir P. In the oil reservoir P, the oil O that has passed through the first oil passage 91 and the second oil passage 92 mix with each other and heat exchange takes place. Therefore, the cooling effect of the cooler 97, which is placed in the path of the first oil passage 91, can also be extended to the oil O that passes through the second oil passage 92. According to this embodiment, the oil O in both oil passages is cooled using one cooler 97 provided in one of the oil passages, the first oil passage 91 or the second oil passage 92.

[0104] Generally, coolers are placed in flow channels through which liquid flows steadily. To cool two oil passages, one possible configuration is to place a cooler in the flow channels contained within each of the two oil passages. In this case, two coolers are required, which increases costs. Alternatively, to cool two oil passages, one could create a flow channel in the region where the two oil passages merge and install a cooler in this flow channel. In this case, since a flow channel needs to be created in the alternating region, the configuration of the flow channels within the oil passages needs to be complicated, resulting in higher costs. According to this embodiment, a cooler is provided only in the first oil passage 91, and the oil O passing through the first oil passage 91 and the second oil passage 92 is mixed in the oil reservoir P, thereby indirectly cooling the second oil passage 92. As a result, the oil O in the first oil passage 91 and the second oil passage 92 can be cooled by a single cooler 97 without complicating the configuration of the flow channels within the oil passage 90. This effect can be achieved when either the first oil passage 91 or the second oil passage 92 has a cooler 97 for cooling the oil O, and the oil O flowing through the first oil passage 91 and the second oil passage 92 merge at the oil reservoir P.

[0105] The heat from the oil O is primarily dissipated through the cooler 97. Additionally, some of the heat from the oil O is dissipated through the housing 6 because the oil O comes into contact with the inner surface of the housing 6. As shown in Figure 1, a heat sink portion 6b with uneven surfaces may be provided on the outer surface of the housing 6. The heat sink portion 6b facilitates the cooling of the motor 2 through the housing 6.

[0106] (First oil passage) In the first oil passage 91, oil O is drawn up from the oil reservoir P by the differential gear 5 and guided into the interior of the rotor 20. Inside the rotor 20, centrifugal force is applied to the oil O as the rotor 20 rotates. As a result, the oil O is evenly diffused toward the stator 30 that surrounds the rotor 20 from the radial outside, cooling the stator 30.

[0107] The first oil passage 91 includes a scooping passage 91a, a shaft supply passage (oil passage) 91b, a shaft internal passage 91c, and a rotor internal passage 91d. A first reservoir 93 is also provided in the path of the first oil passage 91. The first reservoir 93 is located in the housing space 80 (particularly the gear chamber 82).

[0108] The sloshing path 91a is a path through which oil O is sloshed up from the oil reservoir P by the rotation of the ring gear 51 of the differential 5 and received in the first reservoir 93 (see Figure 3).

[0109] As shown in Figure 3, the first reservoir 93 is located above the motor shaft J2, intermediate shaft J4, and differential shaft J5 in the vertical direction. The first reservoir 93 is located between the intermediate shaft J4 and the differential shaft J5 in the vehicle longitudinal direction (horizontal direction, X-axis direction). The first reservoir 93 is located between the motor shaft J2 and the differential shaft J5 in the vehicle longitudinal direction (horizontal direction, X-axis direction). The first reservoir 93 is located on the side of the first gear 41. The first reservoir 93 opens upwards.

[0110] In this specification, "reservoir" means a structure that has the function of storing oil in the absence of a steady flow of liquid in one direction. A "reservoir" differs from a "flow channel" in that there is no steady flow of liquid. The housing space 80 of the motor unit 1 in this embodiment is provided with a first reservoir 93, a second reservoir 98, and a sub-reservoir 95.

[0111] In this embodiment, the differential shaft J5, which is the rotation center of the ring gear 51, is positioned on the rear side of the vehicle relative to the reduction gear 4. When the vehicle moves forward, the differential gear 5 rotates upward in the region opposite to the reduction gear 4. The oil O scooped up by the ring gear 51 of the differential gear 5 circulates on the opposite side from the reduction gear 4 and falls onto the upper side of the first reservoir 93, where it accumulates. That is, the first reservoir 93 receives the oil O scooped up by the ring gear 51. Also, when the oil level in the oil reservoir P is high, such as immediately after the motor 2 is driven, the second gear 42 and the third gear 43 come into contact with the oil O in the oil reservoir P and scoop up the oil O. In such cases, the first reservoir 93 receives the oil O scooped up by the second gear 42 and the third gear 43 in addition to the oil O from the ring gear 51.

[0112] The housing 6 has a gear chamber ceiling portion (ceiling portion) 64 that forms the upper wall of the gear chamber 82. The gear chamber ceiling portion 64 is located above the reduction gear 4 and the differential gear 5. Here, a virtual line (the third line segment described later) L3 is defined that virtually connects the motor shaft J2 and the differential shaft J5 when viewed from the axial direction of the motor shaft J2. The gear chamber ceiling portion 64 is approximately parallel to the virtual line L3. By making the gear chamber ceiling portion 64 approximately parallel to the virtual line L3, a sufficient area is secured for the oil O that is scooped up by the ring gear 51 and scattered in the direction in which the virtual line L3 extends, so that the oil O can be efficiently applied to the first gear 41 that rotates around the motor shaft J. Also, by making the gear chamber ceiling portion 64 approximately parallel to the virtual line L3, it is possible to suppress the housing 6 from becoming larger in the vertical direction. Here, "approximately parallel" between the gear chamber ceiling 64 and the imaginary line L3 means that the angle between the gear chamber ceiling 64 and the imaginary line L3 is 10° or less. If the gear chamber ceiling 64 is curved, the angle between the tangent line at all points of the curve and the imaginary line L3 will be 10° or less. Furthermore, within the range of 10° or less, it is preferable that the gear chamber ceiling 64 approaches the imaginary line L3 as it moves toward either the differential shaft J5 side or the motor shaft J2 side. This makes it possible to miniaturize the housing 6.

[0113] Furthermore, the gear chamber ceiling 64 is a curved surface that curves slightly toward the imaginary line L3 as it moves from the differential shaft J5 side toward the motor shaft J2 side. The curved shape of the gear chamber ceiling 64 is approximately the same as the parabola traced by the oil O scooped up by the ring gear 51, or a curved surface that is slightly away from the ring gear 51. A portion of the oil O scooped up by the ring gear 51 reaches the first reservoir 93 directly. Another portion of the oil O scooped up by the ring gear 51 travels along the gear chamber ceiling 64 of the housing 6 to reach the first reservoir 93. In other words, the gear chamber ceiling 64 plays a role in guiding the oil O to the first reservoir 93.

[0114] The gear chamber ceiling 64 has a protrusion 65 that projects downward. The protrusion 65 is located above the first reservoir 93. Oil O flowing along the gear chamber ceiling 64 forms large droplets at the lower end of the protrusion 65, which fall downward and accumulate in the first reservoir 93. In other words, the protrusion 65 guides the oil O flowing along the gear chamber ceiling 64 to the first reservoir 93. In this embodiment, the motor housing 61 and the gear housing 62 are fixed to each other by bolts 67. The protrusion 65 is provided in the gear chamber ceiling 64 by utilizing the thickened portion around the screw holes into which the bolts 67 are inserted. Note that in Figure 3, the other bolts and other thickened portions around the screw holes that fix the motor housing 61 and the gear housing 62 are not shown.

[0115] The gear chamber ceiling 64 has a plate-shaped overhang 66 that extends along the axial direction. The overhang 66 protrudes downward. The lower end of the overhang 66 is located above the first reservoir 93. Some of the oil O that is scooped up and scattered by the ring gear 51 hits the overhang 66 and flows along its surface. Similarly, the oil O that is scooped up and scattered by the second gear 42 and the third gear is received by the overhang 66 and flows along its surface. The oil O forms large droplets at the lower end of the overhang 66 and falls downward, accumulating in the first reservoir 93. In other words, the overhang 66 guides the scooped-up oil O to the first reservoir 93. The overhang 66 is inclined from the differential shaft J5 side towards the motor shaft J2 side as it moves from the top to the bottom. Because the ring gear 51 has a larger diameter compared to the second gear 42 and the third gear 43, the scattering angle of the oil O is close to horizontal. By arranging the overhang portion 66 at an angle as described above, the oil O scattered from the ring gear 51 can be smoothly adhered to the surface of the overhang portion 66 and fall downwards.

[0116] The first reservoir 93 is located directly above the ring gear 51, the second gear 42, and the third gear 43. The opening of the first reservoir 93 overlaps with the ring gear 51, the second gear 42, and the third gear 43 when viewed from the vertical. Most of the oil scooped up by the gears is scattered directly above the gears that are scooping it up. By positioning the first reservoir 93 directly above the ring gear 51, the second gear 42, and the third gear 43, the oil O scooped up by each gear can be efficiently received.

[0117] The first reservoir 93 has a bottom portion 93a, a first side wall portion 93b, and a second side wall portion 93c. The bottom portion 93a, the first side wall portion 93b, and the second side wall portion 93c extend axially between the wall surfaces of the gear housing portion 62 and the protruding plate portion 61d of the motor housing portion. The first side wall portion 93b and the second side wall portion 93c extend upward from the bottom portion 93a. The first side wall portion 93b constitutes the wall surface of the first reservoir 93 on the differential gear 5 side. The second side wall portion 93c constitutes the wall surface of the first reservoir 93 on the reduction gear 4 side. That is, the first side wall portion 93b extends upward from the end of the bottom portion 93a on the differential shaft J5 side, and the second side wall portion 93c extends upward from the end of the bottom portion 93a on the motor shaft J2 side. The first reservoir 93 temporarily stores oil O in the region enclosed by the bottom portion 93a, the first side wall portion 93b, the second side wall portion 93c, and the wall surfaces of the gear housing portion 62 and the protruding plate portion 61d of the motor housing portion.

[0118] The height of the upper end of the first side wall portion 93b is lower than the height of the upper end of the second side wall portion 93c. The oil O is scooped up by the differential gear 5 and scattered toward the first reservoir 93 from the opposite side of the reduction gear 4. By lowering the height of the upper end of the first side wall portion 93b, the oil O scooped up by the differential gear 5 can be efficiently stored in the first reservoir 93. In addition, the oil O that is scooped up and scattered by the ring gear 51 and exceeds the first side wall portion 93b can be directed toward the second side wall portion 93c and guided toward the first reservoir 93.

[0119] The second side wall portion 93c extends diagonally upward along the circumferential direction of the first gear 41. That is, the second side wall portion 93c inclins toward the motor shaft J2 as it extends upward. As a result, the second side wall portion 93c can receive oil O scooped up by the differential gear 5 over a wide area. In addition, the second side wall portion 93c can receive droplets of oil O running down the ceiling of the storage space 80 over a wide area.

[0120] A shaft supply passage 94 opens at the boundary between the bottom portion 93a and the second side wall portion 93c, toward the interior of the first reservoir 93. In a plan view, the bottom portion 93a is slightly inclined downwards toward the motor shaft J2 side. That is, the bottom portion 93a is slightly inclined so as to become the lower end toward the second side wall portion 93c. Therefore, by providing the opening of the shaft supply passage 94 between the bottom portion 93a and the second side wall portion 93c, the oil O in the first reservoir 93 can be efficiently supplied to the shaft supply passage 94.

[0121] The shaft supply path 91b guides oil O from the first reservoir 93 to the motor 2. The shaft supply path 91b is composed of a shaft supply passage 94. The shaft supply passage 94 extends from the first reservoir 93 toward the end of the shaft 21. The shaft supply passage 94 extends in a straight line. The shaft supply passage 94 slopes downward as it moves from the first reservoir 93 toward the end of the shaft 21. The shaft supply passage 94 is formed by machining a hole in the gear housing 62 that penetrates through to the inside and outside of the housing space 80. The outer opening of the machined hole is closed with a cap (not shown). The shaft supply passage 94 guides the oil O accumulated in the first reservoir 93 from the end of the shaft 21 toward the hollow section 22.

[0122] As shown in Figure 1, the shaft internal path 91c is the path through which oil O passes within the hollow portion 22 of the shaft 21. The rotor internal path 91d is the path through which oil passes from the communication hole 23 of the shaft 21, through the inside of the end plate 26 located on the axial end face 24a of the rotor core 24, and is scattered to the stator 30 (see Figure 5). In other words, the first oil passage 91 has a path that goes from inside the shaft 21 through the rotor core 24.

[0123] In the shaft internal passage 91c, centrifugal force is applied to the oil O inside the rotor 20 as the rotor 20 rotates. As a result, the oil O is continuously scattered radially outward from the end plate 26. In addition, as the oil O is scattered, a negative pressure is created in the internal passage of the rotor 20, and the oil O accumulated in the first reservoir 93 is drawn into the inside of the rotor 20, filling the internal passage of the rotor 20 with oil O. The movement of oil O into the inside of the rotor 20 is also promoted by capillary force in the first oil passage 91. The oil O that reaches the stator 30 absorbs heat from the stator 30.

[0124] (Second oil passage) As shown in Figure 1, in the second oil passage 92, oil O is drawn up from the oil reservoir P to the upper side of the motor 2 and supplied to the motor 2. The oil O supplied to the motor 2 cools the motor 2 by traveling along the outer surface of the stator 30, absorbing heat from the stator 30. The oil O that travels along the outer surface of the stator 30 drips downward and accumulates in the lower region of the motor chamber 81. The oil O in the second oil passage 92 merges with the oil O in the first oil passage 91 in the lower region of the motor chamber 81. The oil O accumulated in the lower region of the motor chamber 81 moves through the partition opening 68 to the lower region of the gear chamber 82 (i.e., the oil reservoir P).

[0125] Figure 10 is a cross-sectional view of the motor unit 1. Note that the cross-sectional view in Figure 10 is shifted axially in each region. The second oil passage 92 has a first passage 92a, a second passage 92b, and a third passage 92c. A pump 96, a cooler 97, and a second reservoir 98 are provided along the path of the second oil passage 92. In the second oil passage 92, oil O is supplied to the motor 2 by passing through each part in the order of the first passage 92a, pump 96, second passage 92b, cooler 97, third passage 92c, and second reservoir 98.

[0126] Pump 96 is an electrically driven electric pump. Pump 96 is mounted in a pump mounting recess 6c provided on the outer surface of the housing 6. Pump 96 has an inlet 96a and a discharge port 96b. The inlet 96a and discharge port 96b are connected via an internal flow path of pump 96. In addition, the inlet 96a is connected to a first flow path 92a. The discharge port 96b is connected to a second flow path 92b. The discharge port 96b is located above the inlet 96a. Pump 96 draws oil O from the oil reservoir P via the first flow path 92a and supplies it to the motor 2 via the second flow path 92b, the cooler 97, the third flow path 92c, and the second reservoir 98.

[0127] The amount of oil O supplied to the motor 2 by the pump 96 is controlled as appropriate according to the operating state of the motor 2. Therefore, when the temperature of the motor 2 rises, such as during prolonged operation or when high output is required, the driving output of the pump 96 is increased, and the amount of oil O supplied to the motor 2 is increased.

[0128] The cooler 97 has an inlet 97a and an outlet 97b. The inlet 97a and the outlet 97b are connected via an internal flow path of the cooler 97. The inlet 97a is also connected to a second flow path 92b. The outlet 97b is connected to a third flow path 92c. The inlet 97a is located closer to the pump 96 (i.e., lower) compared to the outlet 97b. Inside the cooler 97, there is also a cooling water pipe (not shown) through which the cooling water supplied from the radiator passes. The oil O passing through the inside of the cooler 97 is cooled by heat exchange with the cooling water.

[0129] The pump 96 and cooler 97 are fixed to the outer circumferential surface of the motor housing 61 of the housing 6. Viewed from the axial direction of the motor shaft J2, the pump 96 and cooler 97 are located on the opposite side of the differential gear 5 in the horizontal direction, with the motor shaft J2 in between. The pump 96 and cooler 97 are also aligned vertically. The cooler 97 is located above the pump 96. Viewed from the vertical direction, the cooler 97 overlaps with the pump 96.

[0130] According to this embodiment, the pump 96 and cooler 97 are located on opposite sides of the differential gear 5 and the motor shaft J2, allowing for effective use of the space around the motor 2. This makes it possible to reduce the horizontal dimensions of the entire motor unit 1, thereby enabling miniaturization of the motor unit 1.

[0131] According to this embodiment, the pump 96 and the cooler 97 are fixed to the outer circumferential surface of the housing 6. Therefore, compared to the case where the pump 96 and the cooler 97 are provided outside the housing 6, this contributes to miniaturization of the motor unit 1. In addition, because the pump 96 and the cooler 97 are fixed to the outer circumferential surface of the housing 6, a first flow path 92a, a second flow path 92b, and a third flow path 92c that pass through the inside of the wall portion 6a of the housing 6 can be used to form a flow path connecting the housing space 80 and the pump 96 and the cooler 97.

[0132] According to this embodiment, since the cooler 97 is fixed to the outer surface of the housing 6, the distance between the storage space 80 and the cooler 97 can be reduced. As a result, the third flow path 97c connecting the cooler 97 and the storage space 80 can be shortened, and the cooled oil O can be supplied to the storage space 80 at a low temperature.

[0133] The first channel 92a, the second channel 92b, and the third channel 92c pass through the interior of the wall portion 6a of the housing 6 surrounding the containment space 80. The first channel 92a can form the first channel 92a, the second channel 92b, and the third channel 92c as holes formed in the wall portion 6a. Therefore, there is no need to prepare separate pipe materials, which contributes to reducing the number of parts. The first channel 92a passes through the interior of the portion of the wall portion 6a located below the motor 2. The second channel 92b passes through the interior of the portion of the wall portion 6a located horizontally to the side of the motor 2. The third channel 92c passes through the interior of the portion of the wall portion 6a located above the motor 2.

[0134] The first flow path 92a connects the oil reservoir P and the pump 96. The first flow path 92a has a first end 92aa and a second end 92ab. The first end 92aa is located upstream of the second oil passage 92 compared to the second end 92ab. The first end 92aa opens into the housing space 80 below the differential gear 5. When viewed from the vertical, the first end 92aa overlaps with the motor 2. The second end 92ab opens into the pump mounting recess 6c and connects to the suction port 96a of the pump 96.

[0135] As described above, the differential gear 5 and the pump 96 are located on opposite sides of the motor shaft J2 in the horizontal direction. The first flow path 92a extends across the motor 2 on the opposite side in the horizontal direction. The first flow path 92a also passes under the motor 2.

[0136] According to this embodiment, since the first flow path 92a passes under the motor 2, the area under the motor 2 can be effectively utilized, making it possible to reduce the dimensions of the motor unit 1. This makes it possible to miniaturize the motor unit 1.

[0137] The first flow path 92a overlaps with the second gear 42 and the ring gear 51 in at least a portion when viewed from the axial direction. This makes it possible to reduce the dimensions of the motor unit 1 when viewed from the axial direction, thereby miniaturizing the motor unit 1. In this embodiment, the case in which the second gear 42 and the ring gear 51 overlap with the first flow path 92a when viewed from the axial direction, among the multiple gears (first gear 41, second gear 42, third gear 43, and ring gear 51) connected between the motor 2 and the differential gear 5 has been described. However, the above effects can be achieved if at least one of the multiple gears connected between the motor 2 and the differential gear 5 overlaps with the first flow path 92a when viewed from the axial direction.

[0138] The first flow path 92a extends from the lower side of the differential gear 5 to the suction port 96a of the pump 96. The first flow path 92a slopes upward and extends linearly from the first end 92aa to the second end 92ab. The suction port 96a of the pump 96 is located above the lower end of the differential gear 5 and below the motor shaft J2.

[0139] It is preferable to position the pump 96 away from the road surface when the motor unit 1 is mounted on the vehicle, in order to avoid collision with flying stones from the road surface. On the other hand, by positioning the intake port 96a of the pump 96 below the oil level of the oil reservoir P, it is possible to suppress the entrainment of air.

[0140] In this embodiment, the intake port 96a is located below the motor shaft J2. This makes it easier to position the intake port 96a below the oil level of the oil reservoir P. Also, in this embodiment, the intake port 96a is located above the lower end of the differential gear 5. This makes it possible to realize a structure in which the pump 96 is kept away from the road surface. Furthermore, by positioning the intake port 96a below the motor shaft J2, it becomes easier to configure the first flow path 92a in a straight line. Therefore, when a structure is adopted in which the first flow path 92a passes inside the wall portion 6a of the housing 6, the ease of machining the first flow path 92a can be improved.

[0141] In this embodiment, the intake port 96a is located below the liquid level of the oil reservoir P in the containment space 80. The liquid level of the oil reservoir P fluctuates as oil O is supplied from the oil reservoir P to the first oil passage 91 and the second oil passage 92. Even when the liquid level of the oil reservoir P is at its lowest, the intake port 96a is located below the liquid level. In Figure 1, the intake port 96a is depicted as being located above the liquid level of the oil reservoir P. However, Figure 1 is merely a schematic diagram, and the actual intake port 96a is located below the liquid level of the oil reservoir P.

[0142] The second flow path 92b connects the pump 96 and the cooler 97. The second flow path 92b has a first end 92ba and a second end 92bb. The first end 92ba opens into the pump mounting recess 6c and connects to the discharge port 96b of the pump 96. The first end 92ba is located upstream of the second oil passage 92 compared to the second end 92bb. The second end 92bb connects to the inlet 97a of the cooler 97. The second end 92bb is located above the first end 92ba.

[0143] The second flow path 92b has a first path 92bd and a second path 92be. The first path 92bd extends upward from the pump mounting recess 6c. The second path 92be extends horizontally from the upper end of the first path 92bd. The first path 92bd and the second path 92be are each formed by machining holes in the wall portion 6a of the housing 6 that extend from different directions and intersect each other.

[0144] The third flow path 92c connects the cooler 97 to the containment space 80. The third flow path 92c extends linearly along the horizontal direction. The third flow path 92c has a first end 92ca and a second end 92cb. The first end 92ca is located upstream of the second oil passage 92 compared to the second end 92cb. The first end 92ca is connected to the outlet 97b of the cooler 97. The second end 92cb opens into the containment space 80 above the motor 2. That is, the third flow path 92c opens above the motor 2 in the containment space 80. The second end 92cb of the third flow path 92c functions as a supply section 99 that supplies oil O to the second reservoir 98 located in the containment space 80. That is, the second oil passage 92 supplies oil O to the second reservoir 98 at the supply section 99.

[0145] The outlet 97b of the cooler 97 overlaps with the motor 2 in the axial direction of the motor shaft J2. That is, the outlet 97b of the cooler 97 is positioned to overlap with the motor 2 when viewed radially. In other words, the outlet 97b of the cooler 97 is located between both ends of the stator 30 in the axial direction. As a result, the third flow path 92c connecting the outlet 97b of the cooler 97 to the containment space 80 can be shortened, and the cooled oil O can be supplied to the containment space 80 at a low temperature. Furthermore, by positioning the third flow path 97c to overlap with the motor 2 radially, the axial dimension of the motor unit 1 can be reduced, thereby enabling miniaturization of the motor unit 1.

[0146] (Second Reservoir) Figure 11 is a perspective view of the motor unit 1. Figure 12 is a plan view of the second reservoir 98. Note that in Figure 11, the motor housing portion 61 and the closing portion 63 of the housing 6 are not shown.

[0147] As shown in Figure 11, the second reservoir (main reservoir) 98 is located in the motor chamber 81 of the housing space 80. The second reservoir 98 is located above the motor. The second reservoir 98 has a bottom (first bottom 98c and second bottom 98g) and side walls extending upward from the bottom (first side wall 98d, second side wall 98e, third side wall 98f, fourth side wall 98h, fifth side wall 98i, sixth side wall 98j and seventh side wall 98n). The second reservoir 98 stores the oil O supplied to the motor chamber 81 via the supply section 99 of the third flow path 92c in the space surrounded by the bottom and side walls. The second reservoir 98 has multiple outlets (a first outlet 98r, a second outlet 98o, a third outlet 98x, a fourth outlet 98t, a fifth outlet 98u, and a sixth outlet 98v). Each outlet supplies the oil O accumulated in the second reservoir 98 to the motor 2. In other words, the second reservoir 98 supplies the stored oil O to each part of the motor 2 from above via its outlets.

[0148] According to this embodiment, the second reservoir 98 is located above the motor 2 and supplies the stored oil O to the upper side of the motor 2 from multiple outlets. The oil O flows from top to bottom along the outer surface of the motor 2, removing heat from the motor 2, thus cooling the entire motor 2.

[0149] As shown in Figure 12, the second reservoir 98 has a first end 98p located on the gear chamber 82 side in the axial direction, and a second end 98q located on the opposite side of the first end 98p in the axial direction. The second reservoir 98 also has a trough-shaped first storage section 98A extending along the axial direction, and a second storage section 98B located on the second end 98q side relative to the first storage section 98A.

[0150] The first storage section 98A has a first bottom section 98c, a first side wall section 98d, a second side wall section 98e, and a third side wall section 98f. The first storage section 98A is also provided with a first outlet 98r, a second outlet 98o, and a third outlet 98x.

[0151] The first bottom portion 98c is rectangular in shape with its longitudinal direction in the axial direction. Both axial ends of the first bottom portion 98c are located above the coil ends 31a provided at both ends of the stator 30. The first bottom portion 98c is provided with a first outlet 98r. The first outlet 98r is located in the region of the first bottom portion 98c on the end 98p side.

[0152] The first side wall portion 98d and the second side wall portion 98e extend along the axial direction. The first and second side wall portions 98e face each other in the circumferential direction of the motor shaft J2. An inlet 98s is provided in the first side wall portion 98d. The inlet 98s is a U-shaped notch that opens upward. A supply unit 99 is connected to the inlet 98s. The inlet 98s is located in the middle of the axial direction of the first side wall portion 98d. As a result, the inlet 98s can supply oil O to the first end portion 98p and the second end portion 98q, respectively, in the second reservoir 98.

[0153] The second side wall portion 98e is provided with a protrusion 98w that projects toward the first side wall portion 98d. The protrusion 98w is located in front of the inlet 98s. The protrusion 98w has an inclined surface that decreases in height from the center toward the first end portion 98p and the second end portion 98q. The protrusion 98w smoothly divides the oil O that has flowed from the inlet 98s to the second reservoir 98 into the first end portion 98p and the second end portion 98q.

[0154] A second outlet 98o is provided in the second side wall portion 98e. The second outlet 98o is located in the region of the second side wall portion 98e on the first end portion 98p side. The second outlet 98o is located in the vicinity of the first outlet 98r.

[0155] As shown in Figure 11, the third side wall portion 98f is located on the first end 98p side of the second reservoir 98. The third side wall portion 98f is located above one coil end 31a of the stator 30. The height of the upper end of the third side wall portion 98f is lower than the height of the upper ends of the first side wall portion 98d and the second side wall portion 98e. Also, the height of the upper end of the third side wall portion 98f is approximately equal to the height of the lower end of the opening of the second outlet 98o. The space above the second side wall portion 98e functions as a third outlet 98x through which oil O flows out when the liquid level of oil O accumulated in the second reservoir 98 rises.

[0156] The second storage section 98B extends along the circumferential direction of the stator 30. The second storage section 98B has a second bottom section 98g, a fourth side wall section 98h, a fifth side wall section 98i, a sixth side wall section 98j, a seventh side wall section 98n, and a stepped section 98k. The second storage section 98B is also provided with a fourth outlet 98t, a fifth outlet 98u, a sixth outlet 98v, and an overflow section 98y.

[0157] The second bottom portion 98g is located on the second end portion 98q side relative to the first bottom portion 98c. The second bottom portion 98g is located below the first bottom portion 98c. A stepped portion 98k is provided at the boundary between the first bottom portion 98c and the second bottom portion 98g. The second storage portion 98B is located below the first storage portion 98A. The oil O that flows from the first storage portion 98A towards the second end portion 98q accumulates in the second storage portion 98B.

[0158] The second bottom portion 98g is located above one coil end 31a of the stator 30. The second bottom portion 98g is curved along the outer circumference of the motor 2. This allows the capacity of the oil O stored in the second reservoir 98 to be increased without increasing the dimensions of the motor unit 1. The second bottom portion 98g slopes downward from the portion that overlaps with the motor shaft J2 when viewed from above, towards both sides in the circumferential direction. The second storage portion 98B is connected to the first storage portion 98A on one side of the motor shaft J2 when viewed from above.

[0159] As shown in Figure 12, the second storage section 98B is divided into two areas when viewed from above and below: the first area 98gA, which is on one side of the motor shaft J2 and connected to the first storage section 98A, and the second area 98gB, which is on the other side of the motor shaft J2. At the boundary line between the first area 98gA and the second area 98gB, the second bottom 98g is the highest. Oil O that flows from the first storage section 98A to the second storage section 98B first accumulates in the first area 98gA, and when the liquid level in the first area 98gA reaches the height of the boundary line, the oil O flows into the second area 98gB. In this way, the boundary line functions as a weir 98gC provided at the second bottom 98g. In other words, the second bottom portion 98g is provided with a weir 98gC that protrudes upward and divides the second storage portion 98B of the second reservoir 98 into a first region 98gA and a second region 98gB. The oil O flows into one region (first region 98gA), and when the liquid level exceeds the weir 98gC, it flows into the other region (second region 98gB).

[0160] As described later, the sixth side wall portion 98j, which extends along the circumferential direction, is provided with a fourth outlet 98t, a fifth outlet 98u, and a sixth outlet 98v, which are arranged along the circumferential direction. In addition, the fifth side wall portion 98i is provided with an overflow portion 98y. The fourth outlet 98t and the fifth outlet 98u open into the first region 98gA, and the sixth outlet 98v and the overflow portion 98y open into the second region 98gB. In other words, the second reservoir 98 has outlets in each of the multiple regions (first region 98gA and second region 98gB) partitioned by the weir 98gC. For this reason, oil O flows out only from the fourth outlet 98t and the fifth outlet 98u until the liquid level in the first region 98gA exceeds the weir 98gC. Furthermore, after the liquid level in the first region 98gA exceeds the weir 98gC, the oil O flows out from the fourth outlet 98t, the fifth outlet 98u, the sixth outlet 98v, and the overflow section 98y. Therefore, according to this embodiment, the second reservoir 98 can increase the number of outlets through which the oil O flows out as the amount of stored oil O increases. In particular, when the load on the motor 2 increases and the motor 2 becomes hot, the amount of oil O supplied to the second reservoir 98 by the pump 96 increases. Therefore, according to this embodiment, when the motor 2 becomes hot, the number of points through which oil O is supplied to the motor 2 can be increased to broaden the cooling range, and the amount of oil O supplied by the motor 2 can be increased.

[0161] The fourth side wall portion 98h and the fifth side wall portion 98i are located at both ends of the second storage portion 98B in the circumferential direction. The fourth side wall portion 98h and the fifth side wall portion 98i face each other in the circumferential direction. The fourth side wall portion 98h and the fifth side wall portion 98i extend along the axial direction. The fourth side wall portion 98h extends continuously with the first side wall portion 98d toward the second end portion 98q.

[0162] An overflow section 98y is provided in the fifth side wall section 98i. The overflow section 98y is located at the upper end of the fifth side wall section 98i and is a locally lower section. The overflow section 98y is located above the lower ends of the openings of the fourth outlet 98t, the fifth outlet 98u, and the sixth outlet 98v of the second storage section 98B. Therefore, the oil O overflows from the overflow section 98y after the liquid level in the second storage section 98B becomes higher than the fourth outlet 98t, the fifth outlet 98u, and the sixth outlet 98v. A sub-reservoir 95, which will be described later, is provided below the overflow section. The oil O overflowing from the overflow section 98y is stored in the sub-reservoir 95. In this specification, "overflow" means that the liquid in the reservoir flows out when it reaches a certain liquid level. Therefore, if liquid flows out from the bottom of the reservoir, it does not constitute "overflowing."

[0163] The sixth side wall portion 98j is located on the second end 98q side of the second reservoir 98. The sixth side wall portion 96j extends circumferentially. The sixth side wall portion 98j is located above one coil end 31a of the stator 30. The sixth side wall portion 98j is provided with a fourth outlet 98t, a fifth outlet 98u, and a sixth outlet 98v. The fourth outlet 98t, the fifth outlet 98u, and the sixth outlet 98v are holes provided in the sixth side wall portion 98j that penetrate the inside and outside of the second reservoir 98. The fourth outlet 98t, the fifth outlet 98u, and the sixth outlet 98v are aligned circumferentially. As shown in Figure 11, the fourth outlet 98t, the fifth outlet 98u, and the sixth outlet 98v are each of different heights. Therefore, according to this embodiment, the number of outlets from which oil O flows out can be increased according to the liquid level of oil O in the second reservoir 98. This increases the number of oil O supply points to the motor 2, thereby widening the cooling range, and also increases the amount of oil O supplied by the motor 2. This effect can be achieved if at least two of the multiple outlets provided in the second reservoir 98 are at different heights.

[0164] The seventh side wall portion 98n extends along the circumferential direction. The seventh side wall portion 98n faces the sixth side wall portion 98j in the axial direction. The seventh side wall portion 98n is continuous with the stepped portion 98k along the circumferential direction. The seventh side wall portion 97n is provided with a housing portion 98na for housing the fixing screws of the stator core 32.

[0165] According to this embodiment, the second oil passage 92 supplies oil O stored in the second reservoir 98 to the motor 2 from multiple outlets. Each outlet supplies oil O to the motor 2 at a constant flow rate, thereby increasing the cooling efficiency of the motor 2 by the oil O.

[0166] According to this embodiment, the second reservoir 98 has multiple outlets (a first outlet 98r, a second outlet 98o, a third outlet 98x, a fourth outlet 98t, a fifth outlet 98u, and a sixth outlet 98v). Therefore, the second reservoir 98 can supply oil O to the motor 2 from multiple locations simultaneously, and can cool each part of the motor 2 at the same time.

[0167] According to this embodiment, the second reservoir 98 extends along the axial direction. The second reservoir 98 is provided with outlets at both ends in the axial direction. The outlets located at both ends in the axial direction of the second reservoir 98 are located above the coil ends 31a. This allows the coil 31 to be directly cooled by applying oil O to the coil ends 31a located at both ends in the axial direction of the stator 30. More specifically, the oil O applied to the coil 31 seeps in through the gaps between the conductors that make up the coil 31. The oil O that seeps into the coil 31 absorbs heat from the coil as it penetrates the entire coil 31 due to capillary force acting on the conductor tubes and gravity. Furthermore, the oil O accumulates at the bottom of the inner circumferential surface of the stator core 32 and drips down from both ends in the axial direction of the coil 31. Furthermore, the effect of directly cooling the oil O by directly supplying it to the coil end 31a is achieved by having at least two of the multiple outlets located at both axial ends of the second reservoir 98.

[0168] According to this embodiment, the supply unit 99 that supplies oil O to the second reservoir 98 is located between the outlets located at both ends of the second reservoir 98 in the axial direction. Therefore, the oil O supplied from the supply unit 99 can be discharged from the outlets located at both ends.

[0169] (Modified Second Reservoir) Figure 13 is a perspective view of a modified second reservoir 198 that can be used in this embodiment. Components that are the same as those in the above-described embodiment will be described using the same reference numerals. The modified second reservoir 198 is a shallow rectangular box with an opening at the top. The second reservoir 198 has a central oil storage section 198a and four oil supply sections 198b located around the central oil storage section 198a. The central oil storage section 198a and the four oil supply sections 198b are partitioned from each other.

[0170] The central oil reservoir 198a stores the oil O flowing in from the supply section 99. The central oil reservoir 198a is separated from the oil supply section 198b by a circular bottom surface 198ab and a cylindrical wall 198aa extending upward from the bottom surface 198ab.

[0171] The four oil supply units 198b are arranged surrounding the central oil reservoir 198a. Each oil supply unit 198b has a roughly rectangular shape. Near the corners of the two outer walls 198ba of each oil supply unit 198b, which extend in different directions, outlets 198c are provided to communicate with the inside and outside of the oil supply unit 198b. One of the two outlets 198c opens in the axial direction of the motor 2, and the other opens in the circumferential direction. Since each of the four oil supply units 198b has two outlets 198c, the second reservoir 198 has a total of eight outlets 198c.

[0172] The second reservoir 198 is installed above the stator 30 with its bottom surface horizontal. When the oil O supplied from the supply unit 99 fills the central oil reservoir 198a, it overflows from the cylindrical wall 198aa and flows into the four oil supply units 198b. Because the second reservoir 198 is installed horizontally and the cylindrical wall 198aa is at the same height all around, the oil O flows evenly into the four oil supply units 198b. The oil O accumulates in the four oil supply units 198b and flows out to the outside from the outlet 198c.

[0173] The axial length of the second reservoir 198 is longer than the axial length of the stator core 32. Oil O is supplied to the motor 2 from one oil supply section 198b via two outlets 198c facing axially and circumferentially. According to this modification, the second reservoir 198 can supply oil O to the motor 2 in multiple directions from multiple outlets.

[0174] (Sub-reservoir) Figure 14 is a cross-sectional view of the motor unit 1 showing a schematic of the sub-reservoir 95. In Figure 14, the protruding portion 63d provided on the closed portion 63 of the housing 6 is shown by dashed lines. Also in Figure 14, the oil O stored in the sub-reservoir 95 is highlighted with a dot pattern. The sub-reservoir 95 receives the oil O that overflows from the second reservoir 98 in the second oil passage 92. That is, a sub-reservoir 95 that stores oil O is provided in the path of the second oil passage 92. The second reservoir 98 functions as the main reservoir with respect to the sub-reservoir 95. The second reservoir 98 is located upstream of the sub-reservoir 95 in the second oil passage 92.

[0175] The secondary reservoir 95 is located directly below the overflow section 98y. That is, the secondary reservoir 95 and the overflow section 98y overlap when viewed from the vertical direction. This allows the secondary reservoir 95 to receive the oil O that overflows from the second reservoir 98.

[0176] The sub-reservoir 95 has a first portion 95A located on one side in the circumferential direction relative to the second reservoir 98, and a second portion 95B located on the other side in the circumferential direction. The first portion 95A and the second portion 95B are connected to each other. The sub-reservoir 95 has a total of four outlets 61k, two in the first portion 95A and two in the second portion 95B. The four outlets 61k are arranged along the circumferential direction of the motor 2. In addition, the multiple outlets 61k are at different heights from each other.

[0177] The sub-reservoir 95 is composed of the inner surface 61g of the motor housing 61 and the inner wall surface of the protruding portion 63d of the closing portion 63. The inner surface 61g of the motor housing 61 has an inner circumferential surface 61i facing radially inward and an opposing surface 61h facing toward the closing portion 63 in the axial direction. The opposing surface 61h is in contact with the axially facing surface of the protruding portion 63d. Oil O does not leak out from the contact area between the protruding portion 63d and the opposing surface 61h. According to this embodiment, since the sub-reservoir 95 is configured as a gap between other members, there is no need to use other members, and the increase in the number of parts can be suppressed.

[0178] The opposing surface 61h is provided with recesses 61j that are aligned circumferentially and recessed axially. The recesses 61j are recessed in a direction that increases the gap between the inner surface 61g of the motor housing 61 and the inner wall surface of the protruding portion 63d. The oil O flows out downward from the recesses 61j. That is, the recesses 61j constitute an outlet 61k. The outlet 61k is located above the coil end 31a of the stator 30. Therefore, the oil O flowing out from the outlet 61k cools the coil 31 of the coil end 31a. In this embodiment, an example is given in which a recess 61j is provided on the inner surface 61g at the contact portion between the inner surface 61g of the motor housing 61 and the inner wall surface of the protruding portion 63d. However, a recess may also be provided on the inner wall surface of the protruding portion 63d.

[0179] According to this embodiment, by providing a sub-reservoir 95 in addition to the second reservoir 98, oil O can be discharged not only from the outlet of the second reservoir 98 but also from the outlet 61k of the sub-reservoir 95, thereby cooling a wide area of ​​the motor 2. Furthermore, the multiple outlets 61k of the sub-reservoir 95 are arranged in a line along the circumferential direction. This allows the coil ends 31a of the stator 30 to be cooled over a wide area. Moreover, since the multiple outlets 61k are at different heights, the timing of discharge can be varied according to the liquid level of oil O accumulated in the sub-reservoir 95.

[0180] In this embodiment, oil O overflowing from the second reservoir 98 is stored in the sub-reservoir 95. When the motor 2 is under heavy load and its temperature rises, the pump 96 increases the amount of oil O supplied to the second reservoir 98. Therefore, when the motor 2 is under heavy load, oil O overflows from the second reservoir 98, and oil O can also be supplied to the motor 2 at the outlet 61k of the sub-reservoir 95. In this embodiment, when the motor 2 is under heavy load, a wide area of ​​the motor 2 can be cooled by the oil O. That is, by providing the sub-reservoir 95, the supply range of oil O supplied to the motor 2 can be automatically expanded when the operation of the motor 2 changes from a steady state to a heavy load state.

[0181] Furthermore, the lower end of the auxiliary reservoir 95 in this embodiment is located above the motor shaft J2. Therefore, the outlet 61k of the auxiliary reservoir 95 is located above the motor shaft J2. The motor 2 is approximately cylindrical in shape. By positioning the lower end of the auxiliary reservoir 95 above the motor shaft J2, the oil O flowing out from the outlet 61k can be directed along the surface of the motor 2 to cool it. Also, the motor 2 is widest in the horizontal cross-section passing through the motor shaft J2. Because the lower end of the auxiliary reservoir 95 is located above the motor shaft J2, the oil O flowing along the surface of the motor 2 passes through the widest region in the horizontal dimension of the motor. This allows for efficient cooling of the motor 2.

[0182] (Common area of ​​the first and second oil passages) As shown in Figure 1, when the motor 2 is running, oil O is supplied to the motor 2 via the first oil passage 91 and the second oil passage 92. The oil O supplied to the motor 2 drips downwards while cooling the motor 2 and accumulates in the lower area of ​​the motor chamber 81. The oil O accumulated in the lower area of ​​the motor chamber 81 moves to the gear chamber 82 via the partition wall opening 68 provided in the partition wall 61c.

[0183] Figure 15 is a front view of the partition wall 61c of the housing 6 as seen from the motor room 81 side. The partition wall opening 68 is located below the insertion hole 61f through which the shaft 21 is inserted. The partition wall opening 68 has a first opening 68a and a second opening 68b located above the first opening 68a. The first opening 68a and the second opening 68b connect the motor room 81 and the gear room 82, respectively.

[0184] As shown in Figure 19, the lower end of the partition wall opening 68 (i.e., the lower end of the first opening 68a) is located above the lower limit height Lmin of the oil O in the gear chamber 82 when the motor 2 is stationary. Therefore, the partition wall opening 68 allows as much oil O as possible to move into the oil reservoir P when the motor 2 is stopped.

[0185] As shown in Figure 15, the first opening 68a is circular in plan view. The lower end of the first opening 68a is located below the lower end of the stator 30. The first opening 68a is located near the bottom 81a of the motor chamber 81. Therefore, the first opening 68a moves oil O into the gear chamber 82 until the oil O accumulated in the lower region of the motor chamber 81 is almost depleted.

[0186] The first opening 68a coincides with the motor shaft J2 when viewed from above. The first opening 68a is located in a recess 61q provided on the inner circumferential surface of the peripheral wall 61a. The peripheral wall 61a and the recess 61q will now be described. The motor housing 61 of the housing 6 has a peripheral wall 61a that has a cylindrical shape along the outer circumferential surface of the stator 30. A recess 61q is provided on the inner circumferential surface of the peripheral wall 61a that is recessed radially outward. The recess 61q extends along the axial direction. The recess 61q is located directly below the motor shaft J2. That is, the recess 61q coincides with the motor shaft J2 when viewed from above. Because the peripheral wall 61a has a cylindrical shape, the oil O in the motor chamber 81 travels along the inner circumferential surface of the peripheral wall 61a and collects inside the recess 61q. Since the first opening 68a is located in the recess 61q, the oil O in the motor chamber 81 that has been collected inside the recess 61q can be efficiently moved to the gear chamber 82.

[0187] The second opening 68b is located above the first opening 68a. The second opening 68b is a rectangle with its longitudinal direction in the horizontal direction when viewed from above. The second opening 68b has a larger opening area than the first opening 68a. Also, the second opening 68b has a larger width along the horizontal direction compared to the first opening 68a. The second opening 68b has a lower end 68c that extends along the horizontal direction.

[0188] When motor 2 is driven, the amount of oil O supplied to motor 2 per unit time from oil passage 90 (i.e., the first oil passage 91 and the second oil passage 92) increases. As a result, the liquid level of oil O accumulated in the lower region of motor chamber 81 rises. In the partition wall opening 68, the region located below the liquid level of oil O accumulated in the lower region of motor chamber 81 is called the first region S, and the region located above the liquid level is called the second region R. The partition wall opening 68 moves oil O in the first region S to the gear chamber 82. When the liquid level of oil O accumulated in the lower region of gear chamber 82 rises, the area of ​​the first region S increases and the area of ​​the second region R decreases. When the area of ​​the first region S increases, the amount of oil O that moves from motor chamber 81 to gear chamber 82 via the partition wall opening 68 increases.

[0189] In this embodiment, the partition opening 68 is positioned such that when the oil level in the motor chamber 81 rises, the amount of oil O moving from the motor chamber 81 to the gear chamber 82 via the partition opening 68 increases. This prevents the oil level in the motor chamber 81 from becoming too high. In other words, it prevents the rotor 20 in the motor chamber 81 from being submerged in the oil O or excessively stirring up the oil O. Therefore, it is possible to prevent the rotational efficiency of the motor 2 from decreasing due to the flow resistance of the oil O. In addition, according to this embodiment, the oil O in the motor unit 1 can be effectively utilized by moving the oil O in the motor chamber 81 to the gear chamber 82 side according to the height of the oil level in the motor chamber 81. This not only reduces the amount of oil O used and makes the motor unit 1 lighter, but also improves the energy efficiency required for cooling the oil O.

[0190] As shown in Figure 19, the lower end of the second opening 68b is located above the liquid level of the oil O in the gear chamber 82 (upper limit Lmin and lower limit Lmin), regardless of whether the motor 2 is stationary or running. Therefore, the second opening 68b is not submerged in the gear chamber 82. The second opening 68b can move the oil O into the gear chamber 82 regardless of the liquid level in the gear chamber 82, and prevents the rotor 20 from being submerged in the oil O.

[0191] The change in the amount of oil O moving through the partition opening 68 as the liquid level of oil O accumulated in the lower part of the motor chamber 81 rises will be explained in more detail. Here, the liquid level of oil O accumulated in the lower part of the motor chamber 81 that reaches the lower end 68c of the second opening 68b is defined as the first liquid level OL. That is, the lower end of the second opening 68b is located at the first liquid level OL. The first liquid level OL is located above the lower end of the stator 30 and below the lower end of the rotor 20.

[0192] Figure 16 is a graph showing the relationship between the liquid level of oil O accumulated on the lower side of the motor chamber 81 and the area of ​​the first region S. The area of ​​the first region S is correlated (approximately proportional) with the flow rate of oil O flowing out from the partition wall opening 68.

[0193] Oil O is supplied to the motor 2 as it is driven and begins to accumulate in the lower region of the motor chamber 81. The oil O accumulated in the lower region of the motor chamber 81 moves from the motor chamber 81 to the gear chamber 82 through the first opening 68a. When the amount of oil O supplied to the motor 2 per unit time exceeds the flow rate of oil O moving from the motor chamber 81 to the gear chamber 82 through the first opening 68a, the liquid level of oil O accumulated in the lower region of the motor chamber 81 rises. When the liquid level reaches the first liquid level OL, oil O flows out not only from the first opening 68a but also from the second opening 68b. Because the second opening 68b has a larger horizontal width compared to the first opening 68a, the area of ​​the first region S increases sharply before and after the liquid level reaches the first liquid level OL. Consequently, the flow rate of oil O flowing from the motor chamber 81 to the gear chamber 82 through the partition opening 68 increases sharply. As described above, the first liquid level OL is set below the lower end of the rotor 20. Therefore, according to this embodiment, it is possible to suppress the decrease in the rotational efficiency of the rotor 20 in the motor chamber 81 due to the flow resistance of the oil O.

[0194] The horizontal width of the second opening 68b is preferably such that when the liquid level reaches above the first liquid level OL, the flow rate of oil O flowing out from the partition opening 68 is greater than the flow rate of oil O supplied to the motor 2 in the oil passage 90. This prevents the liquid level of oil O accumulating in the lower region of the motor chamber 81 from significantly exceeding the first liquid level OL, thereby preventing the rotor 20 from being submerged in the oil O.

[0195] As shown in Figure 1, the first oil passage 91 includes a churning path 91a and a rotor internal path 91d. The churning path 91a moves oil O from the gear chamber 82 to the motor chamber 81 by churning oil O by the differential gear 5. The amount of oil O churned up by the differential gear 5 depends on the rotational speed of the differential gear 5. Therefore, the amount of oil O moved to the motor chamber 81 in the churning path 91a increases or decreases depending on the vehicle speed. The rotor internal path 91d draws oil O from the gear chamber 82 side to the motor chamber 81 side by the centrifugal force of the rotor 20. The centrifugal force depends on the rotational speed of the rotor 20. Therefore, the amount of oil O moved to the motor chamber 81 in the rotor internal path 91d increases or decreases depending on the vehicle speed. In other words, the amount of oil O moved to the motor chamber 81 in the first oil passage 91 increases or decreases depending on the vehicle speed.

[0196] On the other hand, the second oil passage 92 moves oil O from the gear chamber 82 to the motor chamber 81 by a pump (electric pump) 96. The amount of oil O supplied to the pump 96 is controlled, for example, based on the temperature measurement result of the motor 2. Therefore, the amount of oil O moved to the motor chamber 81 through the second oil passage 92 increases or decreases regardless of the vehicle speed.

[0197] The second oil passage 92 stops the supply of oil O to the motor 2 when the motor 2 is stationary. The second oil passage 92 also starts the movement of oil O to the motor chamber 81 when the motor 2 is started. This allows the oil level in the oil reservoir P of the gear chamber 82 to be raised when the motor is stopped. As a result, the rotation of the motor 2 immediately after startup causes the second gear 42, the third gear 43, and the ring gear 51 to rotate within the oil reservoir P, allowing oil O to spread evenly across the tooth surfaces.

[0198] According to this embodiment, the second oil passage 92 draws oil O from the oil reservoir P regardless of the vehicle speed. Therefore, the second oil passage 92 can lower the oil level of the oil reservoir P even when the vehicle is traveling at low speed. This prevents the rotational efficiency of the gears in the gear chamber 82 from being reduced by the oil O in the oil reservoir P during low-speed driving.

[0199] (Modified Partition Opening) Figure 17 is a front view of a modified partition opening 168 that can be used in this embodiment. Components that are the same as those in the above-described embodiment will be described using the same reference numerals. The modified partition opening 168 has an elongated hole portion 168a extending in the vertical direction, and a wide expanded portion 168b that connects to the elongated hole portion 168a above it. The lower end of the elongated hole portion 168a is located near the bottom 81a of the motor chamber 81. The elongated hole portion 168a overlaps with the motor shaft J2 when viewed from the vertical direction. The expanded portion 168b is wider in the horizontal direction than the elongated hole portion 168a. The expanded portion 168b is a rectangle with the horizontal direction as its longitudinal direction when viewed from above. The expanded portion 168b has a lower end 168c that extends in the horizontal direction. The lower end 168c is located at the first liquid level OL described above. In the partition wall opening 168, the region located below the liquid surface of the oil O is called the first region S, and the region located above the liquid surface is called the second region R.

[0200] Figure 18 is a graph showing the relationship between the liquid level of the oil O accumulated below the motor chamber 81 and the area of ​​the first region S in this modified example. In this modified example, when the liquid level reaches the first liquid level OL, the oil O flows out not only from the elongated hole 168a but also from the expanded portion 168b, and the area of ​​the first region S increases rapidly. Consequently, the flow rate of oil O flowing from the motor chamber 81 to the gear chamber 82 through the partition opening 168 increases rapidly. Since the first liquid level OL is set below the lower end of the rotor 20, the decrease in the rotational efficiency of the rotor 20 due to the flow resistance of the oil O can be suppressed.

[0201] (Liquid level of oil reservoir) As shown in Figure 1, when the motor 2 is running, the pump 96 drives the first oil passage 91 to supply oil O from the oil reservoir P to the motor 2. Also, when the motor 2 is running, the differential gear 5 pushes the oil O from the oil reservoir P to the first reservoir 93 through the first oil passage 91, supplying oil O to the inside of the motor 2. In other words, both the first oil passage 91 and the second oil passage 92 supply oil O from the oil reservoir P to the motor 2 when the motor 2 is running. Therefore, when the motor 2 is running, the liquid level of the oil reservoir P located in the lower region of the gear chamber 82 decreases. Also, since the oil O supplied to the motor 2 accumulates in the space below the motor chamber 81, when the motor 2 is running, the liquid level of the oil O accumulated in the lower region of the motor chamber 81 increases.

[0202] On the other hand, when the motor 2 is stopped, the first oil passage 91 and the second oil passage 92 stop supplying oil O to the motor 2. As a result, the oil O that drips down below the motor 2 accumulates in the lower region of the motor chamber 81 and then moves through the partition opening 68 to the oil reservoir P in the lower region of the gear chamber 82. Therefore, when the motor 2 is stopped, the liquid level of oil O accumulated in the lower region of the motor chamber decreases, and the liquid level of the oil reservoir P located in the lower region of the gear chamber 82 increases.

[0203] Figure 19 is a side view showing the arrangement of each gear located inside the gear chamber 82. Note that in Figure 19, the gear housing portion 62 of the housing 6 and the bearings supporting each shaft are omitted. As shown in Figure 19, according to this embodiment, the height of the oil level O accumulated in the oil reservoir P fluctuates between an upper limit height Lmax and a lower limit height Lmin as the oil O is supplied to the oil passages 90 (first oil passage 91 and second oil passage 92). As shown in Figure 1, the first oil passage 91 is provided with a first reservoir 93. The second oil passage 92 is provided with a second reservoir 98 and a sub-reservoir 95 (omitted in Figure 1, see Figure 14). Furthermore, oil O accumulates in the lower region of the motor chamber 81 where the first oil passage 91 and the second oil passage 92 merge. In this way, several locations where oil O accumulates are provided along the paths of the first oil passage 91 and the second oil passage 92. As a result, when oil O is supplied to the motor 2, the oil O that accumulates in the oil reservoir P moves to the reservoir etc. along the aforementioned path, and the liquid level of the oil reservoir P drops. Consequently, the gears in the gear chamber 82 are exposed from the oil O in the oil reservoir P, thereby improving the rotational efficiency of the gears.

[0204] As shown in Figure 19, of the pair of gears (second gear 42 and third gear 43) that rotate around the intermediate shaft J4, the lower end of the larger diameter second gear 42, which is connected to the motor 2, is located below the upper limit height Lmax of the liquid level. Also, the lower end of the second gear 42 is located above the lower limit height Lmin of the liquid level. Similarly, of the pair of gears (second gear 42 and third gear 43) that rotate around the intermediate shaft J4, the lower end of the smaller diameter third gear 43, which is connected to the differential 5, is located below the upper limit height Lmax of the liquid level. Also, the lower end of the third gear 43 is located above the lower limit height Lmin of the liquid level.

[0205] The liquid level in the oil reservoir P reaches its upper limit height Lmax when the motor 2 stops and the supply of oil O from the oil reservoir P to the motor 2 stops. According to this embodiment, when the motor 2 is stopped, a portion of the second gear 42 and the third gear 43 can be immersed in the oil O of the oil reservoir P. As a result, when the motor 2 is driven, the oil O can be immediately distributed to the tooth surfaces of the second gear 42 and the third gear 43, thereby improving the transmission efficiency between the gears.

[0206] The liquid level of the oil reservoir P reaches its lower limit height Lmin when the motor 2 is driven under high load and the supply of oil O from the oil reservoir P to the motor 2 is most efficiently promoted. According to this embodiment, when the motor 2 is in operation, the second gear 42 and the third gear 43 are located above the liquid level of the oil reservoir P, thus suppressing the decrease in rotational efficiency of the second gear 42 and the third gear 43 caused by the flow resistance of the oil O. This makes it possible to increase the driving efficiency of the motor unit 1.

[0207] The ring gear 51, which is provided in the differential gear 5 and connected to the reduction gear 4, and rotates around the differential shaft J5, has its lower end positioned below the liquid level at the upper limit height Lmax and the lower limit height Lmin of the liquid level. According to this embodiment, regardless of fluctuations in the liquid level of the oil reservoir P, at least a portion of the ring gear 51 is positioned below the liquid level of the oil O in the oil reservoir P. Therefore, even when the motor 2 is driven and the liquid level of the oil reservoir P drops, the ring gear 51 can scoop up oil O from the oil reservoir P, supplying oil O to the tooth surfaces of each gear in the gear chamber 82, thereby increasing the torque transmission efficiency between each gear.

[0208] (Summary of oil passages) Referring to Figure 1, the flow of oil O in the oil passage 90 accompanying the operation of the motor unit 1 will be explained. When the motor unit 1 is installed in a hybrid vehicle or a plug-in hybrid vehicle, it operates in one of the following modes: engine mode, which is driven only by the engine; motor mode, which is driven only by the motor 2; and hybrid mode, which is driven by both the engine and the motor.

[0209] In engine mode, motor 2 is stopped, but the differential 5 is driven by the engine, so oil O is drawn up from oil reservoir P. The drawn-up oil O accumulates in the first reservoir 93, but since the rotor 20 does not rotate, it is not scattered towards the stator 30. Also, in engine mode, pump 96 is not driven, and oil O is not supplied to the second oil passage 92.

[0210] In motor mode and hybrid mode, when the vehicle is going uphill, the output of motor 2 increases, and the amount of heat generated by motor 2 increases. In such cases, the discharge rate of pump 96 is increased to supply more oil O to the stator 30, thereby accelerating cooling. On the other hand, when the vehicle is going downhill (i.e., when there is no load on motor 2), or when motor 2 has not reached a high temperature, such as when the vehicle is starting up or when used in cold climates, the discharge rate of pump 96 is reduced.

[0211] The second oil passage 92 can adjust the amount of oil supplied to the motor 2 by the pump 96 according to the temperature of the motor 2, the vehicle's driving mode, etc. According to this embodiment, the energy required to cool the motor 2 can be made more efficient. This effect can be achieved when the pump 96 is an electrically driven pump. The discharge amount of the pump 96 can be managed based on temperature data detected by a temperature sensor installed on the motor 2. Furthermore, by combining data such as the vehicle's operating history, driving conditions, vehicle attitude, ambient temperature, and the weight of the occupants and cargo, it is possible to predict the temperature change of the motor 2. Based on this predicted temperature change, the motor 2 may be managed to prevent it from becoming overheated.

[0212] According to this embodiment, the oil passage 90 supplies oil O to the stator 30 from multiple locations, thereby efficiently cooling the entire stator 30. Furthermore, according to this embodiment, the oil O functions as both a cooling oil and a lubricating oil. Therefore, there is no need to provide separate passages for the cooling oil and the lubricating oil, which can reduce costs.

[0213] (Measures against contamination in oil passages) The oil O used to cool the motor unit 1 is also used to lubricate the differential gear 5 and the reduction gear 4. Therefore, there is a risk that contaminants such as metal powder generated by mechanical contact may be mixed into the oil O. These contaminants may worsen the fluidity of the oil O in the first oil passage 91 and the second oil passage 92. The contaminants are removed by periodic replacement of the oil O. In addition, means for capturing contaminants may be provided in either the first oil passage 91 or the second oil passage 92, or both. As an example, as shown in Figure 9, a permanent magnet 98m may be installed in the second reservoir 98 to magnetically capture contaminants and suppress their diffusion. In this case, deterioration of the fluidity of the oil O can be suppressed.

[0214] (Arrangement of each axis) The motor axis J2, intermediate axis J4, and differential axis J5 extend parallel to each other along the horizontal direction. The intermediate axis J4 and differential axis J5 are located below the motor axis J2. Therefore, the reduction gear 4 and differential gear 5 are located below the motor 2.

[0215] Viewed from the axial direction of the motor shaft J2, the line segment virtually connecting the motor shaft J2 and the intermediate shaft J4 is defined as the first line segment L1, the line segment virtually connecting the intermediate shaft J4 and the differential shaft J5 is defined as the second line segment L2, and the line segment virtually connecting the motor shaft J2 and the differential shaft J5 is defined as the third line segment L3.

[0216] In this embodiment, the second line segment L2 extends along a substantially horizontal direction. That is, the intermediate shaft J4 and the differential shaft J5 are aligned substantially horizontally. Therefore, the reduction gear 4 and the differential gear 5 can be aligned horizontally, and the vertical dimension of the motor unit 1 can be reduced. In addition, the oil O scooped up by the differential gear 5 can be efficiently applied to the reduction gear 4. This allows oil O to be supplied to the tooth surfaces of the gears constituting the reduction gear 4, thereby increasing the transmission efficiency of the gears. Note that the diameters of the gears (second gear 42 and third gear 43) that rotate around the intermediate shaft J4 are smaller than the diameter of the ring gear 51 that rotates around the differential shaft J5. In this embodiment, because the second line segment L2 extends along a substantially horizontal direction, the intermediate shaft J4 and the differential shaft J5 are arranged substantially horizontally. Therefore, depending on the height of the oil level in the oil reservoir P, only the ring gear 51 may be submerged in the oil reservoir P, while the second gear 42 and the third gear 43 may not be submerged. Thus, the ring gear 51 can scoop up the oil O from the oil reservoir P while suppressing a decrease in the rotational efficiency of the second gear 42 and the third gear 43. In this embodiment, the second line segment L2 being approximately horizontal means a direction within ±10° of the horizontal direction.

[0217] According to this embodiment, the angle α between the second line segment L2 and the third line segment L3 is 30° ± 5°. This improves the transmission efficiency of the oil O scooped up by the differential gear 5 between the first gear 41 and the second gear 42, and allows for the realization of a desired gear ratio. If the angle α exceeds 35°, it becomes difficult to supply the oil scooped up by the differential gear to the gear (first gear) that rotates around the motor shaft. This may reduce the transmission efficiency between the first gear and the second gear. On the other hand, if the angle α is less than 25°, the output gear in the transmission process cannot be made sufficiently large, making it difficult to achieve a desired gear ratio on the three axes (motor shaft, intermediate shaft, and differential shaft).

[0218] In this embodiment, the first line segment L1 extends along a substantially vertical direction. That is, the motor shaft J2 and the intermediate shaft J4 are aligned along a substantially vertical direction. Therefore, the motor 2 and the reduction gear 4 can be aligned along a vertical direction, and the horizontal dimensions of the motor unit 1 can be reduced. Furthermore, by making the first line segment L1 substantially vertical, the motor shaft J2 can be positioned closer to the differential shaft J5, and the oil O scooped up by the differential gear 5 can be supplied to the first gear 41 which rotates around the motor shaft J2. This makes it possible to increase the transmission efficiency between the first gear 41 and the second gear 42. In this embodiment, the first line segment L1 being substantially vertical means a direction within ±10° of the vertical direction.

[0219] The lengths L1 of the first line segment, L2 of the second line segment, and L3 of the third line segment satisfy the following relationship: L1:L2:L3 = 1:1.4~1.7:1.8~2.0. Also, the reduction ratio in the reduction mechanism from motor 2 to differential gear 5 is 8 or more and 11 or less. According to this embodiment, a desired gear ratio (8 or more and 11 or less) can be achieved while maintaining the positional relationship of the motor shaft J2, intermediate shaft J4, and differential shaft J5 as described above.

[0220] <Parking Mechanism> Figure 20 shows a parking mechanism 7 that can be used in the motor unit 1 of this embodiment. The parking mechanism 7 is effective when the motor unit 1 is used in an electric vehicle (EV). In a manual transmission vehicle driven by an engine, in addition to activating the parking brake, setting the transmission to a position other than neutral can apply a load to the engine and provide a braking effect. In an automatic transmission vehicle, in addition to activating the parking brake, setting the shift lever to the parking position can lock the transmission. On the other hand, in an electric vehicle, there is no braking mechanism other than the parking brake that applies the brakes to the vehicle, so the motor unit 1 requires a parking mechanism 7.

[0221] The parking mechanism 7 consists of a ring-shaped parking gear 71, a parking pawl 72, a parking rod 73, and a parking lever 74. The parking gear 71 is arranged coaxially with the second gear (intermediate gear) 42 and the third gear 43. The parking gear 71 is fixed to the intermediate shaft 45. The parking pawl 72 has a projection 72a that engages with the groove of the parking gear 71 to prevent the rotation of the parking gear 71. The parking rod 73 is connected to the parking pawl 72 and moves the projection 72a along the radial direction of the parking gear. The parking lever 74 is connected to the parking rod 73 and drives the parking rod 73.

[0222] When motor 2 is operating, the parking pawl 72 retracts from the parking gear 71. On the other hand, when the shift lever is in the parking position, the parking pawl 72 engages with the parking gear 71, preventing the parking gear 71 from rotating.

[0223] The parking pole 72 is controlled by a parking motor (not shown) connected to the parking lever. Using a parking motor allows the parking mechanism 7 to be motorized, thus simplifying the components required to drive the parking mechanism 7. Furthermore, using a parking motor allows the parking pole 72 to be driven by a push button or paddle lever, improving driver operability. Such a mechanism is called a shift-by-wire system. However, the parking mechanism 7 may be manually operated instead of electrically operated using a shift-by-wire system. That is, the driver may drive the parking pole by mechanically pulling a wire connected to the parking lever.

[0224] According to this embodiment, the parking mechanism 7 is provided on the intermediate shaft 45. This allows for a reduction in the braking torque required to prevent the rotation of the parking gear 71 during the torque transmission process from the motor 2 to the axle 55, compared to the case where the parking mechanism 7 is provided on a gear downstream of the intermediate shaft. This makes it possible to miniaturize and lighten the structure of the parking mechanism. Furthermore, if the parking mechanism 7 is electrically operated, a smaller motor can be used for parking. In addition, if the parking mechanism is manually operated, the burden on the driver can be reduced.

[0225] Furthermore, according to this embodiment, the parking mechanism 7 is located below the reduction gear 4. Therefore, the parking pawl 72 is immersed in the oil O of the oil reservoir P, and the oil O is interposed between the parking gear 71 and the projection 72a of the parking pawl 72, allowing for smooth attachment and detachment of the projection 72a. Note that the parking mechanism 7 in this embodiment is just one example, and other conventionally known structures may be adopted. Also, the parking mechanism 7 may be arranged to apply braking force to the shaft 21 or ring gear 51 connected to the motor 2.

[0226] <Modification 1> <Disconnection Mechanism> Figure 21 is a partial cross-sectional view showing the disconnection mechanism 107 of the motor unit 101 of Modification 1. Modification 1 describes a modified motor unit 101 equipped with a disconnection mechanism 107 in the torque transmission path from the motor 2 to the axle 55. The main difference of this modified motor unit 101 is that the disconnection mechanism 107 is provided on the shaft 121 of the motor 2. Components that are the same as those in the above-described embodiment will be described using the same reference numerals.

[0227] The disconnection mechanism 107 is provided when the motor unit 101 is installed in a hybrid electric vehicle (HEV) or a plug-in hybrid vehicle (PHV). Hybrid electric vehicles and plug-in hybrid vehicles operate in one of three modes: engine mode, where the engine drives the vehicle; motor mode, where the motor 2 drives the vehicle; and hybrid mode, where both the engine and the motor drive the vehicle. In a vehicle operating in engine mode, the disconnection mechanism 107 disconnects the power transmission mechanism of the motor unit 101 (motor 2 rotor 20, reduction gear 4, differential gear 5) from the axle 55 so that the stationary motor 2 does not become a load.

[0228] As shown in Figure 21, in this modified example, the shaft 121 has a first shaft portion 121A, a connecting shaft portion 121C, and a second shaft portion 121B arranged coaxially, and a separation mechanism 107 located between the connecting shaft portion 121C and the second shaft portion 121B. The first shaft portion 121A, the connecting shaft portion 121C, and the second shaft portion 121B are arranged in this order along the axial direction. That is, the connecting shaft portion 121C is located between the first shaft portion 121A and the second shaft portion 121B.

[0229] The shaft 121 is a hollow shaft provided with a hollow section 122 having an inner circumferential surface extending along the motor shaft J2. The hollow section 122 includes a first hollow section 122A located inside the first shaft section 121A, a second hollow section 122B located inside the second shaft section 121B, and a third hollow section 122C located inside the connecting shaft section 121C. The first hollow section 122A, the second hollow section 122B, and the third hollow section 122C are aligned along the axial direction and communicate with each other.

[0230] The first shaft portion 121A is positioned in the motor chamber 81 of the housing space 80. The first shaft portion 121A is located radially inward of the stator 30 and penetrates the rotor core 24 along the motor shaft J2. The first shaft portion 121A has a first end portion 121e located on the output side (i.e., the reduction gear 4 side).

[0231] The first end portion 121e passes through an insertion hole 61f provided in the partition wall 61c from the motor chamber 81 side. A first hollow portion (second recess) 122A opens on the axially facing surface of the first end portion 121e. The first end portion 121e is rotatably supported by a first bearing 89 which is held in contact with the surface of the partition wall 61c facing the motor chamber 81 side. By holding the first bearing 89 in contact with the surface of the partition wall 61c facing the motor chamber 81 side, the axis of the first shaft portion 121A can be aligned at the motor chamber 81 side of the housing 6. This allows for high-precision axis alignment of the first shaft portion 121A with respect to the stator 30.

[0232] The connecting shaft portion 121C is positioned inside the insertion hole 61f. The connecting shaft portion 121C is rotatably supported by a second bearing 188A, which is held in contact with the surface of the partition wall 61c facing the gear chamber 82. The second bearing 188A is a ball bearing. The connecting shaft portion 121C is provided with a stepped surface 121q facing the partition wall 61c. The stepped surface 121q is in contact with the inner ring of the second bearing 188A.

[0233] In this modified example, the second bearing 188A is held on the surface of the partition wall 61c facing the gear chamber 82. Therefore, the connecting shaft portion 121C can be assembled to the first shaft portion 121A after the first shaft portion 121A has been aligned. Thus, the assembly process of the connecting shaft portion 121C can be simplified.

[0234] The outer diameter of the second bearing 188A is larger than that of the first bearing 89. When the separation mechanism 107 is in operation, the second bearing 188A is subjected to a large load in both the axial and circumferential directions. In this modified example, the second bearing 188A has a larger diameter compared to the first bearing 89, which ensures sufficient strength against the load during the operation of the separation mechanism 107.

[0235] The connecting shaft portion 121C has a second end portion 121f, a third end portion 121g, and a connecting flange portion 121h.

[0236] The second end 121f protrudes toward the motor chamber 81. The second end 121f is located toward the first shaft portion 121A and is connected to the first end 121e of the first shaft portion 121A. The second end 121f is housed in the first hollow portion 122A which opens toward the first end 121e. The outer circumferential surface of the second end 121f fits into the inner circumferential surface of the first hollow portion 122A. By fitting the second end 121f into the first hollow portion 122A, the connection between the first end 121e and the second end 121f can be made smaller in the radial direction. This makes it possible to secure space to place the first bearing 89 radially outward from the first end 121e.

[0237] The third end portion 121g protrudes toward the gear chamber 82. The third end portion 121g is located opposite the second end portion 121f and toward the second shaft portion 121B. A first recess 121p is provided at the axial end of the third end portion 121g. The connecting flange portion 121h extends radially outward from the third end portion 121g. The diameter of the connecting flange portion 121h is larger than the smallest diameter portion of the through hole 61f.

[0238] In this modified example, the connecting shaft portion 121C is a separate component from the first shaft portion 121A. Therefore, by assembling the connecting shaft portion 121C to the first shaft portion 121A after the motor 2 assembly process, assembly can be performed in the same order as when the separation mechanism 107 is absent. Accordingly, the shapes of the parts other than the shaft 121 can be the same as when the separation mechanism 107 is absent. In other words, in this modified example, parts can be standardized between the motor unit 101 equipped with the separation mechanism 107 and the motor unit 1 without the separation mechanism 107. Furthermore, since the assembly order can be the same regardless of the presence or absence of the separation mechanism 107, the complexity of part shapes and the increase in the number of parts can be suppressed. Therefore, in this modified example, a highly versatile and low-cost motor unit 101 can be provided.

[0239] The second shaft portion 121B is positioned in the gear chamber 82 of the housing space 80. The second shaft portion 121B has a fourth end portion 121i and a fifth end portion 121j.

[0240] The fourth end portion 121i is located on the third end portion 121g side of the connecting shaft portion 121C. Power transmission between the fourth end portion 121i and the connecting flange portion 121h of the connecting shaft portion 121C is selectively disconnected by the disconnection mechanism 107.

[0241] The fourth end portion 121i is housed in a first recess 121p provided in the third end portion 121g. A needle bearing (bearing) 121n is provided in the radial gap between the third end portion 121g and the fourth end portion 121i. In other words, according to this modified example, the second shaft portion 121B is rotatably supported by the connecting shaft portion 121C at the fourth end portion 121i. Therefore, according to this modified example, stable holding can be achieved without hindering relative rotation when the second shaft portion 121B and the connecting shaft portion 121C are separated by the separation mechanism 107. This effect can be achieved when either the third end portion 121g or the fourth end portion 121i is provided with a first recess that houses the other via the needle bearing 121n.

[0242] In this modified example, the needle bearing 121n is composed of multiple cylindrical members arranged in a ring shape, but other bearing mechanisms such as ball bearings may be used instead of the needle bearing 121n. However, by employing needle bearings, the radial dimensions of the third end 121g and the fourth end 121i can be reduced, thereby miniaturizing the motor unit 101.

[0243] As described above, the first shaft portion 121A, the connecting shaft portion 121C, and the second shaft portion 121B are each provided with hollow portions 122 that extend axially and communicate with one another. Similar to the embodiment described above, oil O for cooling the inside of the motor is supplied to the hollow portion 122 from the second shaft portion 121B side toward the first shaft portion 121A side. In this modified example, the connecting shaft portion 121C and the second shaft portion 121B are connected via a needle bearing 121n. Therefore, the third hollow portion 122C of the connecting shaft portion 121C and the second hollow portion 122B of the second shaft portion 121B can be connected to each other. This allows oil O to be supplied to the hollow portion 122 and used as an oil passage.

[0244] The fifth end 121j is located on the opposite side of the fourth end 121i. The fifth end is rotatably supported by a third bearing 188B held in the housing. That is, the second shaft portion 121B is supported at the fifth end 121j by the third bearing 188B. According to this modified example, the second shaft portion 121B is supported by two bearings aligned in the axial direction (needle bearing 121n and third bearing 188B). Similarly, the connecting shaft portion 121C is supported by two bearings aligned in the axial direction (second bearing 188A and needle bearing 121n). The second shaft portion 121B and the connecting shaft portion 121C are rotatably supported at two points aligned in the axial direction, allowing them to rotate stably without axial runout.

[0245] A first gear 41 is provided on the outer circumferential surface of the second shaft portion 121B. The first gear 41 is located between the fourth end portion 121i and the fifth end portion 121j. The first gear 41 transmits power to the second gear 42 of the reduction gear 4. In this modified example, the first gear 41 is located between the second bearing 188A and the third bearing 188B. Therefore, the first gear 41 can rotate stably relative to the motor shaft J2, and the torque generated by the motor 2 can be stably transmitted to the second gear 42.

[0246] The disconnection mechanism 107 surrounds the connecting flange portion 121h of the connecting shaft portion 121C and the fourth end portion 121i of the second shaft portion 121B from the radially outer side. The disconnection mechanism 107 uses the drive unit 175 to switch between a state in which the connecting flange portion 121h and the fourth end portion 121i are not mechanically connected and a state in which they are connected.

[0247] The separation mechanism 107 is located in the axial direction between the axial end face of the motor 2 and the first gear 41. The motor unit 101 employs a three-axis structure consisting of a motor shaft J2, an intermediate shaft J4, and a differential shaft J5. In addition, a third gear 43 is located in the axial direction between the axial end face of the motor 2 and the first gear 41. The second gear 42 rotates synchronously with the second gear 42 which is connected to the first gear 41. A gap larger than the thickness of the third gear 43 is provided between the axial end face of the motor 2 and the first gear 41. According to this modified example, the separation mechanism 107 is arranged between the axial end face of the motor 2 and the first gear 41. That is, the third gear 43 and the separation mechanism 107 are arranged in positions that overlap in the axial direction. This makes effective use of the internal space of the gear chamber 82 and allows for miniaturization of the motor unit 101.

[0248] According to this modified version, the disconnection mechanism is provided on the shaft 121 of the motor 2. That is, the disconnection mechanism 107 is provided in the part of the power transmission path from the motor 2 to the axle 55 where the torque is smallest. According to this modified version, since the torque transmitted through the disconnection mechanism 107 is small, the disconnection mechanism can be made smaller.

[0249] The disconnection mechanism 107 in this modified example is referred to as a rotational synchronization device or a synchromesh mechanism. Note that in this modified example, the disconnection mechanism 107 is just one example. For example, a dog clutch mechanism or a multi-stage clutch mechanism may be used as the disconnection mechanism.

[0250] The disconnection mechanism 107 includes a sleeve 171, a clutch hub 172, a synchronizer ring 173, a key 174, and a drive unit (not shown).

[0251] The clutch hub 172 is fixed to the outer circumferential surface of the second shaft portion 121B. The clutch hub 172 rotates together with the second shaft portion 121B around the motor shaft J2. An external spline is provided on the outer circumference of the clutch hub 172.

[0252] The sleeve 171 is movable along the axial direction. The sleeve 171 engages with the external splines of the clutch hub 172 and rotates integrally with the sleeve 171. In addition, splines are provided on the inner circumferential surface of the sleeve 171. The splines of the sleeve 171 engage with splines provided on the outer circumferential surface of the connecting flange portion 121h after the clutch hub 172 and the connecting flange portion 121h have rotated synchronously. This connects the second shaft portion 121B and the connecting shaft portion 121C.

[0253] The key 174 is held in the sleeve 171. The key 174 moves axially with the sleeve 171. The key 174 aligns the phases of the splines provided on the sleeve 171 and the connecting flange portion 121h, respectively.

[0254] The synchronizer ring 173 moves axially together with the sleeve 171. The synchronizer ring 173 has a tapered surface that increases in inner diameter as it approaches the connecting flange portion 121h. On the other hand, the connecting flange portion 121h is provided with a boss portion that protrudes toward the synchronizer ring 173 side along the axial direction. The boss portion has a tapered surface that faces the synchronizer ring 173. The synchronizer ring 173 and the connecting flange portion 121h rotate synchronously by bringing their tapered surfaces into contact with each other.

[0255] A drive unit (not shown) is connected to the sleeve 171. The drive unit moves the sleeve 171 in the axial direction.

[0256] Figure 22 is a conceptual diagram showing the state in which the motor 2 and the reduction gear 4 are connected by the disconnection mechanism 107, and Figure 23 is a conceptual diagram showing the state in which the motor 2 and the reduction gear 4 are disconnected by the disconnection mechanism 107. As described above, the motor unit 101 equipped with the disconnection mechanism 107 is installed in a hybrid vehicle or a plug-in hybrid vehicle. In such a vehicle, when switching between a mode in which the vehicle is driven only by the engine and a mode in which it is driven using the power of the motor 2, the drive unit 175 operates to switch the connection and disconnection between the connecting shaft portion 121C and the second shaft portion 121B.

[0257] The control of the disconnection mechanism 107 will now be explained. When the disconnection mechanism 107 switches from the disconnected state to the connected state, first, the rotational speed of the second shaft section 121B is calculated from the rotational speed of the axle 55. Next, the rotational speed of the motor 2 is increased to the calculated rotational speed of the second shaft section 121B. While the rotational speed of the motor 2 is increasing, the sleeve is moved by the drive unit 175, and the connection between the second shaft section 121B and the connecting shaft section 121C is achieved. After that, the position where the connection between the second shaft section 121B and the connecting shaft section 121C is completed is calculated from the cumulative rotational speed of the drive unit 175. Finally, it is detected that the rotational speed of the motor 2 and the rotational speed of the second shaft section 121B calculated from the rotational speed of the axle 55 are the same, and it is determined that the connection state is complete.

[0258] <Control> Each element of the motor unit 1, such as the motor 2, pump 96, the drive unit 175 of the disconnection mechanism 107, and the parking motor of the parking mechanism 7, is centrally controlled by a microcontroller unit (MCU). The microcontroller unit may be provided integrated with the motor unit 1 or provided externally.

[0259] <Vehicle Mountability> The motor unit 1 can be applied to hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHVs), and electric vehicles (EVs). Furthermore, the motor unit 1 can be applied not only to passenger cars but also to cargo vehicles (trucks), etc. The motor unit 1 may be mounted on either the front or rear side of the vehicle, but it is preferable to mount it on the rear side. Because the motor unit 1 of this embodiment has small vertical dimensions, it can be compactly installed even on the rear side, where installation space is limited due to constraints between the cargo area and the minimum ground clearance.

[0260] Although embodiments and modifications of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments. [Explanation of symbols]

[0261] 1,101…Motor unit (electric drive device), 2…Motor, 4…Reduction gear, 5…Differential gear, 6…Housing, 6a…Wall section, 20…Rotor, 21,121…Shaft, 21A,121A…First shaft section, 21B,121B…Second shaft section, 21c…Flange section, 21c…Flange section (cover section), 21d…Screw section, 21e,121e…First end section, 21f,121f…Second end section, 21g,121g…Third end section, 21h,121i…Fourth end section, 22,122…Hollow section, 22A,122A…First hollow section, 22q…Second region (small diameter hollow section), 22r…Third region (large 22t…Second stepped surface (stepped surface), 22u…Recessed groove, 23…Communication hole, 24…Rotor core, 24a…Axial end face, 24b…Outer peripheral surface, 24d…Magnet holding hole, 24e…Core through hole, 25…Rotor magnet, 26,126,226…End plate, 26a,126a,226a…First surface, 26b,126b,226b…Second surface, 26e,126u…Inclined surface, 26f,61j,61q…Recess, 26j,126j,226j…First recessed groove (first recess), 26k,126k,226k,226kA,226kB…Second recessed groove (second Recessed section), 26p, 126p, 226p... Plate through-holes, 26r... Second opening (open section), 26s... First opening (open section), 26t... Oil passage, 28... Washer (cover section), 29... Nut, 30... Stator, 31... Coil, 31a... Coil end, 32... Stator core, 41... First gear, 42... Second gear (intermediate gear), 43... Third gear, 51... Ring gear, 61... Motor housing section, 61c... Partition wall, 61f... Through-hole, 61k, 97b, 98r, 98o, 98x, 98t, 98u, 98v, 198c... Outlet, 63... Closed section, 63d... Protrusion Section, 64...Gear chamber ceiling section (ceiling section), 65...Protruding section, 66...Eaves section, 68,168...Partition wall opening, 68a...First opening, 68b...Second opening, 80...Accommodation space, 81...Motor chamber, 82...Gear chamber, 88,188A...Second bearing, 89...First bearing, 90...Oil passage, 91...First oil passage (oil passage), 91a...Scooping path, 91b...Shaft supply path (oil passage), 92...Second oil passage (oil passage), 92a...First passage, 92b...Second passage, 92c, 92aa,92ba,92ca...First end, 92ab,92bb,92cb...Second end,97c...Third flow path, 93...First reservoir (reservoir), 95...Sub-reservoir, 96...Pump (electric pump), 96a...Inlet, 97...Cooler, 98,198...Second reservoir (main reservoir), 98y...Overflow section, 99...Supply section, 107...Disconnection mechanism, 121C...Connecting shaft section, 121h...Connecting flange section, 121j...Fifth end section, 121n...Needle bearing (bearing), 1 21p…First recess, 121q…Stepped surface, 126r,226r…Open section, 128,228…Lid section, 168a…Elongated hole section, 168b…Expansion section, 98gC…Weir, J2…Motor shaft, J4…Intermediate shaft, J5…Differential shaft, L1…First line segment, L2…Second line segment, L3…Third line segment (imaginary line), Lmax…Upper height limit, Lmin…Lower height limit, O…Oil, OL…First liquid level, P…Oil reservoir, S…First region

Claims

1. A motor having a rotor that rotates around a motor shaft extending in the axial direction, A differential device connected to the motor, A housing is provided in which a housing space is provided for housing the motor and the differential, It comprises an oil passage for supplying oil to the motor, The differential has a ring gear that is rotatable about a differential axis parallel to the motor shaft, The oil passage includes an electric pump fixed to the outer surface of the housing and a cooler for cooling the oil. At least a portion of the motor is located on one side of the differential shaft and on the other side of at least a portion of the electric pump, in a direction perpendicular to both the axial and vertical directions. The aforementioned oil passage is A second flow path connecting the electric pump and the cooler, It has a third flow path connecting the cooler and the containment space, The cooler is positioned on top of the electric pump. Motor unit.

2. A motor having a rotor that rotates around a motor shaft extending in the axial direction, A differential device connected to the motor, A housing is provided in which a housing space is provided for housing the motor and the differential, It comprises an oil passage for supplying oil to the motor, The differential has a ring gear that is rotatable about a differential axis parallel to the motor shaft, An electric pump is provided in the oil passage. At least a portion of the motor is located on one side of the differential shaft and on the other side of at least a portion of the electric pump, in a direction perpendicular to both the axial and vertical directions. At least a portion of the ring gear and the motor overlap in the axial direction. Motor unit.

3. The cooler is fixed to the outer surface of the housing, The motor unit according to claim 1.

4. A cooler for cooling the oil is provided in the oil passage. The aforementioned oil passage is A second flow path connecting the electric pump and the cooler, It has a third flow path connecting the cooler and the containment space, The cooler is fixed to the outer surface of the housing. The motor unit according to claim 2.

5. A motor having a rotor that rotates around a motor shaft extending in the axial direction, A differential device connected to the motor, A housing is provided in which a housing space is provided for housing the motor and the differential, It comprises an oil passage for supplying oil to the motor, The differential has a ring gear that is rotatable about a differential axis parallel to the motor shaft, An electric pump and a cooler for cooling the oil are provided in the oil passage. At least a portion of the motor is located on one side of the differential shaft and on the other side of at least a portion of the electric pump, in a direction perpendicular to both the axial and vertical directions. The aforementioned oil passage is A second flow path connecting the electric pump and the cooler, It has a third flow path connecting the cooler and the containment space, The housing has walls surrounding the aforementioned storage space, The second and third flow paths are provided inside the wall portion. The cooler is positioned on top of the electric pump. Motor unit.

6. The motor has a stator located radially outward from the rotor, The outlet of the cooler is located in the axial direction between the ends of the stator. A motor unit according to any one of claims 1, 3, 4, or 5.

7. The oil passage has a first flow path provided on the vertically lower side of the motor, The first flow path is, A first end opening into the aforementioned storage space, It has a second end connected to the suction port of the electric pump, The first end is located vertically below the differential shaft. A motor unit according to any one of claims 1 to 6.

8. The motor is connected to the differential via a plurality of gears, The oil passage has a first flow path provided on the vertically lower side of the motor, At least a portion of the first flow path overlaps axially with at least one of the plurality of gears, A motor unit according to any one of claims 1 to 6.

9. The oil passage has a first flow path provided on the vertically lower side of the motor, At least a portion of the first flow path overlaps the differential in the axial direction. A motor unit according to any one of claims 1 to 6.

10. The first flow path is inclined vertically upward from the first end to the second end. The motor unit according to claim 7.

11. The differential shaft is located vertically below the motor shaft. The suction port of the electric pump is located vertically above the vertical lower end of the differential and vertically below the motor shaft. A motor unit according to any one of claims 1 to 10.

12. Viewed from the axial direction, at least a portion of the electric pump is located on the opposite side of the differential shaft from the motor shaft, A motor unit according to any one of claims 1 to 11.

13. Viewed from the axial direction, at least a portion of the electric pump overlaps the motor in the vertical direction. A motor unit according to any one of claims 1 to 12.

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