Drive unit

Abstract

[Problem] To reduce the amount of oil discharged to the outside of a drive unit.　[Solution] This drive unit comprises a housing that accommodates a motor, a power transmission mechanism connected downstream of the motor, and a shaft connected downstream of the power transmission mechanism and penetrating the motor and the power transmission mechanism. An oil reservoir in which the motor and the power transmission mechanism are immersed is formed within the housing. When a direction parallel to a rotation axis is defined as an axial direction, a breather is disposed in an upper portion of the housing in an axially central portion of the housing.

Description

Drive unit

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

[0002] Patent Document 1 discloses a breather structure.

[0003] Japanese Unexamined Patent Application Publication No. 2012-82930

[0004] There is a demand for reducing the amount of oil discharged to the outside of the drive unit.

[0005] The drive unit according to an aspect of the present invention includes a housing that houses a motor, a power transmission mechanism connected downstream of the motor, and a shaft connected downstream of the power transmission mechanism and penetrating the motor and the power transmission mechanism. An oil reservoir in which the motor and the power transmission mechanism are immersed is formed in the housing. When the direction parallel to the rotation axis is defined as the axial direction, a breather is disposed at the upper portion of the housing and at the axial center of the housing.

[0006] According to an aspect of the present invention, the amount of oil discharged to the outside of the drive unit can be reduced.

[0007] FIG. 1 is a diagram for explaining a drive unit. FIG. 2 is a diagram for explaining a vehicle equipped with the drive unit. FIG. 3 is a diagram for explaining a vehicle traveling on a horizontal road surface. FIG. 4 is a diagram for explaining an oil reservoir in the housing. FIG. 5 is a diagram for explaining a vehicle traveling on an inclined surface. FIG. 6 is a diagram for explaining an oil reservoir in the housing. FIG. 7 is a diagram for explaining a vehicle traveling on an inclined surface. FIG. 8 is a diagram for explaining an oil reservoir in the housing. FIG. 9 is a diagram for explaining a vehicle traveling on an inclined surface. FIG. 10 is a diagram for explaining an oil reservoir in the housing. FIG. 11 is a diagram for explaining a vehicle traveling on an inclined surface. FIG. 12 is a diagram for explaining an oil reservoir in the housing. FIG. 13 is a diagram for explaining the installation range of the breather. FIG. 14 is a diagram for explaining the installation range of the breather. FIG. 15 is a diagram for explaining a drive unit according to a modified example. FIG. 16 is a diagram for explaining a drive unit according to a modified example.

[0008] First, the definitions of terms used in this specification will be explained. "Drive unit" means a device that includes a motor that generates power, or a motor and a mechanism for transmitting power (e.g., gears, transmission mechanism, etc.). Therefore, the term "drive unit" is used as a broad concept that includes both motor units, which include only a motor, and power transmission devices, which have a power transmission mechanism in addition to a motor. "Drive unit" is also called a "motor unit," "power transmission device," or "unit." A motor unit is a drive unit that has at least a motor. A power transmission device is a device that has at least a power transmission mechanism, and the power transmission mechanism is, for example, a gear mechanism and / or a differential gear mechanism. A drive unit, which is a device that has a motor and a power transmission mechanism, belongs to both the concepts of a motor unit and a power transmission device.

[0009] A "housing" is something that houses at least a motor and gears. A housing consists of one or more cases.

[0010] A "motor" is a rotating electric machine that has both electric motor and / or generator functions.

[0011] A "breather" consists of a breather inlet, a breather chamber, and a breather pipe.

[0012] When it is stated that element B (part, component, etc.) is connected to element A (component, component, etc.), that element B (component, component, etc.) is connected downstream of element A (component, component, etc.), or that element B (component, component, etc.) is connected upstream of element A (component, component, etc.), it means that element A and element B are connected in a way that allows for power transmission. The power input side is the upstream side, and the power output side is the downstream side. In addition, element A and element B may be connected via other elements (clutch, other gear mechanisms, etc.).

[0013] "Overlapping in a specified direction" means that multiple elements are aligned in a specified direction, and is synonymous with the description "overlapping in a specified direction." The "specified direction" can be, for example, the axial direction, radial direction, direction of gravity, or vehicle travel direction (vehicle forward direction, vehicle reverse direction). If multiple elements (parts, sections, etc.) are shown aligned in a specified direction in the drawing, it can be assumed that there is a description in the specification explaining that they overlap in a specified direction.

[0014] "Not overlapping in a given direction" and "offset in a given direction" mean that multiple elements are not aligned in a given direction, and are equivalent to stating "not overlapping in a given direction" and "offset in a given direction." "Given direction" can be, for example, axial direction, radial direction, direction of gravity, or vehicle travel direction (vehicle forward direction, vehicle reverse direction). If a drawing shows that multiple elements (parts, sections, etc.) are not aligned in a given direction, it can be assumed that the description in the specification includes a statement explaining that they do not overlap in a given direction.

[0015] The statement "In a predetermined viewing direction, element A (part, etc.) is located between element B (part, etc.) and element C (part, etc.)" means that when observed from a predetermined direction, element A can be observed to be located between element B and element C. The "predetermined direction" is, for example, the axial direction, the radial direction, the direction of gravity, the direction of vehicle travel (vehicle forward direction, vehicle reverse direction), etc. For example, if elements B, A, and C are arranged in this order along the axial direction, then in a radial viewing direction, element A can be said to be located between element B and element C. If the drawing shows that element A is located between element B and element C in a predetermined viewing direction, it can be assumed that there is a sentence in the specification explaining that element A is located between element B and element C in a predetermined viewing direction.

[0016] When two elements (parts, components, etc.) overlap in an axial view, the two elements are coaxial.

[0017] "Axial direction" refers to the axial direction of the rotation axis of the components that make up the drive unit. "Radial direction" refers to the direction perpendicular to the rotation axis of the components that make up the drive unit. Components include, for example, motors, gear mechanisms, differential gear mechanisms, etc.

[0018] The embodiments will be described below. In the embodiments, a drive unit 1 mounted on a vehicle will be used as an example. Figure 1 is a diagram illustrating the drive unit 1. Figure 2 is a diagram illustrating the vehicle V on which the drive unit 1 is mounted. Figure 2 corresponds to a view of the vehicle V on which the drive unit 1 is mounted, taken from the direction of the A-A arrow in Figure 1.

[0019] Here, "vertical direction" in the drawings refers to the vertical direction relative to the state in which the drive unit 1 is mounted on the vehicle. Therefore, "upper side" refers to the "upper side" in the vertical direction, and "lower side" refers to the "lower side" in the vertical direction. Also, "front-rear direction" refers to the front-rear direction of the vehicle relative to the state in which the drive unit 1 is mounted on the vehicle. Therefore, "front side" refers to the "front side" in the front-rear direction, and "rear side" refers to the "rear side" in the front-rear direction. Also, "left-right direction" refers to the width direction of the vehicle relative to the state in which the drive unit 1 is mounted on the vehicle. Therefore, "right side" refers to the "right side" in the vehicle width direction, and "left side" refers to the "left side" in the vehicle width direction.

[0020] As shown in Figure 1, the drive unit 1 includes a motor 2 and a power transmission mechanism 3 that transmits the output rotation of the motor 2 to the drive shafts 7 (7A, 7B).

[0021] The power transmission mechanism 3 includes a first planetary gear 4, a second planetary gear 5, and a differential mechanism 6. The first planetary gear 4 is connected downstream of the motor 2. The second planetary gear 5 is connected downstream of the first planetary gear 4. The differential mechanism 6 is connected downstream of the second planetary gear 5. The drive shafts 7 (7A, 7B) are connected downstream of the differential mechanism 6.

[0022] In this embodiment, the drive unit 1 has the rotation axes of the first planetary gear 4, the second planetary gear 5, and the differential mechanism 6, and the axis of the drive shaft 7 (7A, 7B) arranged coaxially with the rotation axis X of the motor 2.

[0023] In the drive unit 1, the output rotation of the motor 2 is shifted (for example, reduced) by the first planetary gear 4 and the second planetary gear 5 and input to the differential mechanism 6, and then output to the left and right drive wheels WH, WH (see Figure 3) of the vehicle via the drive shafts 7 (7A, 7B).

[0024] The drive unit 1 has a housing HS that accommodates a motor 2, a power transmission mechanism 3, and drive shafts 7 (7A, 7B). Based on the installation state of the drive unit 1 on the vehicle, the rotation axis X of the motor 2 is positioned along the vehicle width direction (left-right direction in the figure).

[0025] The housing HS includes a motor case 10 that houses the motor 2 and a gear case 14 that houses the power transmission mechanism 3. The gear case 14 is provided adjacent to the motor case 10 in the direction of the motor 2's rotation axis X.

[0026] The motor case 10 includes a case member 11 and a cover member 12 joined to the case member 11. The case member 11 and the cover member 12 are joined to each other in the direction of the rotation axis X.

[0027] The case member 11 has a support wall portion 111 surrounding the rotation axis X. The support wall portion 111 is provided in a direction along the rotation axis X. The motor 2 is housed inside the support wall portion 111. A cover member 12 is connected to one end 111a of the support wall portion 111 in the direction of the rotation axis X by bolts (not shown). A gear case 14 is connected to the other end 111b of the support wall portion 111 by bolts (not shown).

[0028] The cover member 12 has a wall portion 120 perpendicular to the rotation axis X and a peripheral wall portion 121 surrounding the outer circumference of the wall portion 120. The peripheral wall portion 121 is joined to one end 111a of the support wall portion 111 of the case member 11 from the direction of the rotation axis X. In this state, the opening on the one end 111a side of the case member 11 is closed by the cover member 12.

[0029] In the wall portion 120, a cylindrical motor support portion 125 is provided in the region where the rotation axis X intersects. One end 20a of the motor shaft 20 of the motor 2 passes through the motor support portion 125 in the direction of the rotation axis X. A bearing B1 is supported on the inner circumference of the motor support portion 125. The outer circumference of the motor shaft 20 is supported by the motor support portion 125 via the bearing B1.

[0030] Furthermore, the motor case 10 has a lid member 13 that is joined to the cover member 12. The lid member 13 is provided on the side opposite to the case member 11 in the rotation axis X direction when viewed from the cover member 12.

[0031] The cover member 13 has a wall portion 130 perpendicular to the rotation axis X and a peripheral wall portion 131 surrounding the outer circumference of the wall portion 130. In the wall portion 130, the drive shaft 7B penetrates in the direction of the rotation axis X in the region where the rotation axis X intersects. Inside the peripheral wall portion 131, the wall portion 130 is provided with a cylindrical drive shaft support portion 135 that surrounds the drive shaft 7B. The peripheral wall portion 131 of the cover member 13 is connected to the wall portion 120 of the cover member 12 from the direction of the rotation axis X by bolts (not shown).

[0032] The drive shaft support portion 135 is provided on the wall portion 130 facing the cover member 12. A bearing B5 is supported on the inner circumference of the drive shaft support portion 135. The outer circumference of the drive shaft 7B is supported by the drive shaft support portion 135 via the bearing B5.

[0033] The gear case 14 includes a first case member 15, a second case member 16, and a cover member 17. The first case member 15, the second case member 16, and the cover member 17 are joined in this order along the rotation axis X direction. The first case member 15 is joined to the motor case 10. The second case member 16 is joined to the first case member 15 from the side opposite to the motor case 10. The cover member 17 is joined to the second case member 16.

[0034] The first case member 15 has a support wall portion 151 that surrounds the rotating shaft X. The first planetary gear 4 of the power transmission mechanism 3 is housed inside the support wall portion 151. The first case member 15 is provided with a wall portion 150 that extends inward from the support wall portion 151 between the motor 2 and the first planetary gear 4.

[0035] In the wall portion 150, a cylindrical motor support portion 155 is provided in the region where the rotation axis X intersects. The other end 20b of the motor shaft 20 of the motor 2 passes through the motor support portion 155 in the direction of the rotation axis X. A bearing B2 is supported on the inner circumference of the motor support portion 155. The outer circumference of the motor shaft 20 is supported by the motor support portion 155 via the bearing B2.

[0036] The space within the housing HS is divided into two by the wall 150. The space on the motor 2 side of the wall 150 (left side in the figure) is the motor room Sa that houses the motor 2. The space on the first planetary gear 4 side of the wall 150 (right side in the figure) is the gear room Sb that houses the power transmission mechanism 3.

[0037] Furthermore, the wall portion 150 is provided with through holes 150a that penetrate in the direction of the rotation axis X. Multiple through holes 150a are provided at intervals in the circumferential direction around the rotation axis X. The motor chamber Sa and the gear chamber Sb are in communication with each other through the through holes 150a. Therefore, oil OL and air in the housing HS can flow between the motor chamber Sa and the gear chamber Sb.

[0038] The second case member 16 is joined to the support wall portion 151 of the first case member 15 from the opposite side of the motor case 10. The second case member 16 has a peripheral wall portion 161 that surrounds the rotating shaft X. The peripheral wall portion 161 is provided with a wall portion 160 that extends inward between the first planetary gear 4 and the second planetary gear 5. The first planetary gear 4 of the power transmission mechanism 3 is housed in the space sandwiched between the wall portion 150 of the first case member 15 and the wall portion 160 of the second case member 16.

[0039] In the wall portion 160, a cylindrical carrier support portion 165 is provided in a region where the rotation axis X intersects. A bearing B3 is supported on the inner circumference of the carrier support portion 165. The carrier support portion 165 supports the carrier 55 of the second planetary gear 5 via the bearing B3.

[0040] On the peripheral wall portion 161 of the second case member 16, a cover member 17 is joined from the side opposite to the first case member 15. The cover member 17 has a wall portion 170 orthogonal to the rotation axis X and a peripheral wall portion 171 surrounding the outer circumference of the wall portion 170. The outer diameter of the peripheral wall portion 171 gradually increases as it moves away from the wall portion 170 in the rotation axis X direction.

[0041] The cover member 17 is joined to the second case member 16 with the opening of the peripheral wall portion 171 facing the second case member 16 side. In this state, the opening of the peripheral wall portion 171 is blocked by the second case member 16. The second planetary gear 5 and the differential mechanism 6 of the power transmission mechanism 3 are housed in a space surrounded by the second case member 16 and the cover member 17.

[0042] As shown in FIG. 1, the motor 2 has a motor shaft 20, a cylindrical rotor core 21 externally inserted into the motor shaft 20, a stator core 22 surrounding the outer circumference of the rotor core 21, and a coil 23 provided in the stator core 22. The stator core 22 is fixed to the inner circumference of the support wall portion 111 of the case member 11.

[0043] The motor shaft 20 is a hollow cylindrical member. A sun gear 41 of the first planetary gear 4 is inserted on the other end 20b side of the motor shaft 20. The motor shaft 20 and the sun gear 41 are connected so as not to be relatively rotatable by spline fitting.

[0044] The first planetary gear 4 has a sun gear 41, a ring gear 42, a pinion gear 43, a pinion shaft 44, and a carrier 45. In the first planetary gear 4, the sun gear 41 serves as an input portion of the output rotation of the motor 2. The carrier 45 that supports the pinion shaft 44 serves as an output portion of the input rotation.

[0045] The sun gear 41 is provided so as to be relatively rotatable with respect to the drive shaft 7B while being externally inserted into the drive shaft 7B. The ring gear 42 is fixed to the inner circumference of the support wall portion 151 of the first case member 15. The pinion gear 43 meshes with the outer circumference of the sun gear 41 and the inner circumference of the ring gear 42. The pinion gear 43 is rotatably supported by a pinion shaft 44.

[0046] The carrier 45 supports the end on the motor 2 side and the end on the second planetary gear 5 side of the pinion shaft 44, and a cylindrical connecting portion 451 is externally inserted into the sun gear 51 of the second planetary gear 5. The connecting portion 451 and the sun gear 51 are connected so as not to be relatively rotatable by spline fitting.

[0047] The second planetary gear 5 includes a sun gear 5, a ring gear 52, a stepped pinion gear 53, a pinion shaft 54, and a carrier 55. In the second planetary gear 5, the sun gear 51 serves as an input portion of the output rotation of the first planetary gear 4. The carrier 55 that supports the pinion shaft 54 serves as an output portion of the input rotation.

[0048] The sun gear 51 is provided so as to be relatively rotatable with respect to the drive shaft 7B while being externally inserted into the drive shaft 7B. The sun gear 51 meshes with the large-diameter gear portion 531 of the stepped pinion gear 53 so as to be rotationally transmissible.

[0049] The stepped pinion gear 53 has a large-diameter gear portion 531 that meshes with the sun gear 51 and a small-diameter gear portion 532 that is smaller in diameter than the large-diameter gear portion 531. The stepped pinion gear 53 is a gear component in which the large-diameter gear portion 531 and the small-diameter gear portion 532 are arranged side by side in the rotation axis X direction and are integrally provided. The small-diameter gear portion 532 is located on the differential mechanism 6 side (right side in the figure) when viewed from the large-diameter gear portion 531.

[0050] The small-diameter gear portion 532 meshes with the inner circumference of the ring gear 52. The ring gear 52 is spline-fitted to the inner circumference of the peripheral wall portion 171 of the cover member 17. The relative rotation of the ring gear 52 with respect to the cover member 17 is restricted.

[0051] The pinion shaft 54 ​​passes through the large-diameter gear portion 531 and the small-diameter gear portion 532 of the stepped pinion gear 53 in the direction of the rotation axis X. The stepped pinion gear 53 is rotatably mounted on the pinion shaft 54. Both ends of the pinion shaft 54 ​​are supported by carriers 55.

[0052] The carrier 55 is rotatably supported on the inner circumference of the carrier support portion 165 of the second case member 16 via a bearing B3, on the side of the first planetary gear 4 as viewed from the pinion shaft 54. The carrier 55 is connected to the differential case 60 on the side of the differential mechanism 6 as viewed from the pinion shaft 54.

[0053] The differential case 60 has a cylindrical support portion 601 that surrounds the rotation axis X. The support portion 601 extends along the rotation axis X in a direction away from the second planetary gear 5. The outer circumference of the support portion 601 is rotatably supported by a bearing B4 on the inner circumference of the peripheral wall portion 171 of the cover member 17 on the wall portion 170 side.

[0054] In the second planetary gear 5, the output rotation of the motor 2, which has been reduced by the first planetary gear 4, is input from the carrier 45 to the sun gear 51. The output rotation input to the sun gear 51 is reduced by the stepped pinion gear 53, and then output from the carrier 55 to the differential case 60.

[0055] The differential case 60 is a hollow member having an internal space capable of housing the pinion mate shaft 61, the pinion gears 62, 62, and the side gears 63, 63. Inside the differential case 60, the pinion mate shaft 61 is supported by the differential case 60 in a direction perpendicular to the axis of rotation X. The pinion gears 62, 62 are rotatably supported on the pinion mate shaft 61. When the differential case 60 rotates around the axis of rotation X, the pinion gears 62, 62 rotate together with the differential case 60 around the axis of rotation X.

[0056] Inside the differential case 60, pinion gears 62, 62 and side gears 63, 63 connected to drive shafts 7A, 7B are meshed in a rotationally transmittable manner. Drive shaft 7B passes through the side gears 63, the second planetary gear 5, the first planetary gear 4, and the motor 2 in the direction of the rotation axis X. Drive shaft 7A passes through the side gears 63, the support portion 601 in the direction of the rotation axis X. That is, drive shafts 7 (7A, 7B) pass through the motor 2 and the power transmission mechanism 3. When the differential case 60 rotates around the rotation axis X, the rotation of the differential case 60 is transmitted to the left and right drive shafts 7A, 7B via the pinion gears 62, 62 and the side gears 63, 63.

[0057] Thus, in the drive unit 1, the output rotation of the motor 2 is reduced by the first planetary gear 4 and the second planetary gear 5 and input to the differential mechanism 6, and then output to the left and right drive wheels WH of the vehicle (see Figure 3) via the drive shafts 7A and 7B.

[0058] As shown in Figure 2, the drive unit 1 is connected to the front wheels of the vehicle V. The width direction (left-right direction in the figure) of the housing HS is oriented along the longitudinal direction of the vehicle V. The drive shaft 7A is connected to the left drive wheel WH of the vehicle at the front of the page. The drive shaft 7B (see Figure 1) is connected to the right drive wheel WH of the vehicle at the back of the page (see Figure 3).

[0059] In the following explanation, unless otherwise specified, the sides of each case component constituting the housing HS will be collectively referred to as the top surface HSa, bottom surface HSb, right side surface HSc, left side surface HSd, front surface HSe, and back surface HSf of the housing HS (see Figures 1 and 2).

[0060] As shown in Figure 1, the upper surface HSa and lower surface HSb of the housing HS are the upper and lower surfaces, respectively, of the support wall portion 111 of the case member 11, the peripheral wall portion 121 of the cover member 12, the peripheral wall portion 131 of the lid member 13, the support wall portion 151 of the first case member 15, the peripheral wall portion 161 of the second case member 16, and the peripheral wall portion 171 of the cover member 17, with the rotation axis X in between. The right side surface HSc of the housing HS is the surface formed by the wall portion 130 of the lid member 13. The left side surface HSd of the housing HS is the surface formed by the wall portion 170 of the cover member 17. Furthermore, as shown in Figure 2, the front HSe and rear HSf of the housing HS are the front and rear surfaces, respectively, of the support wall portion 111 of the case member 11, the peripheral wall portion 121 of the cover member 12, the peripheral wall portion 131 of the lid member 13, the support wall portion 151 of the first case member 15, the peripheral wall portion 161 of the second case member 16, and the peripheral wall portion 171 of the cover member 17, with the rotation axis X in between.

[0061] As shown in Figure 2, with reference to the installation state of the drive unit 1 on the vehicle V, an inverter INV, which is a power conversion device for the motor 2, is provided on the upper surface HSa of the housing HS. As shown in Figure 1, the inverter INV is provided in the direction of the rotation axis X, extending from the motor 2 across the first planetary gear 4 to the large-diameter gear portion 531 side of the second planetary gear 5. The inverter INV is electrically connected to the coil 23 of the motor 2 via a busbar (not shown).

[0062] In the drive unit 1, power to drive the motor 2 is supplied from the inverter INV. When power is supplied to the coil 23 of the motor 2, a magnetic field is generated around the stator core 22. As a result, the rotor core 21 and the motor shaft 20 rotate around the rotation axis X, driving the motor 2.

[0063] Inside the housing HS, oil is stored for cooling the motor 2 and lubricating the meshing parts of the power transmission mechanism 3. This oil forms an oil reservoir OT at the bottom of the motor chamber Sa and gear chamber Sb. When the rotation of the motor 2's rotor core 21 and the power transmission mechanism 3 stirs up and scatters the oil in the oil reservoir OT, the pressure inside the housing HS may rise. Therefore, the housing HS is provided with a breather 8 to release the increased pressure.

[0064] As shown in Figure 1, the breather 8 is located on the upper surface HSa of the housing HS, away from the oil reservoir OT. The breather 8 is oriented along a straight line Lz1 that crosses the middle (center) of the housing HS in the direction of the rotation axis X. The length from the straight line Lz1 in the direction of the rotation axis X to the right side surface HSc of the housing HS and the length from the straight line Lz1 to the left side surface HSd of the housing HS are both half the total length L of the housing HS (L / 2). In other words, the breather 8 is located in the axial center when the direction parallel to the rotation axis X is considered as the axial direction.

[0065] In the drive unit 1 according to this embodiment, the inverter INV and the support wall portion 151 of the first case member 15 are located at a position through which the straight line Lz1 passes. The breather 8 is provided so as to penetrate the inverter INV and the support wall portion 151 of the first case member 15 in the vertical direction.

[0066] The breather 8 includes a breather pipe 81 that penetrates vertically through the inverter INV and the support wall portion 151 of the first case member 15, and a filter 80 that closes the opening of the breather pipe 81. In the breather 8, the opening 811 at the lower end of the breather pipe 81 constitutes the breather inlet, and the opening 812 at the upper end constitutes the breather outlet. The filter 80 closes the opening 812 at the upper end of the breather pipe 81.

[0067] Here, the support wall portion 151 of the first case member 15 is provided with a recess 159 in the region above the rotation axis X, which is recessed away from the coil 23 of the motor 2. The opening 811 of the breather 8 is connected to the recess 159. Therefore, the recess 159 functions as a breather chamber. The breather 8 connects the motor chamber Sa of the housing HS to the outside. As a result, the pressure that has risen inside the housing HS is released to the atmosphere outside through the breather 8. In Figure 1, the shape of the recess 159 (breather chamber) is shown in a simplified manner, but the recess 159 may also be provided with a labyrinth structure that prevents oil from entering the opening 811 side.

[0068] In this embodiment, the example given is that the breather 8 penetrates the support wall portion 151 of the first case member 15, but the embodiment is not limited to this. For example, if the support wall portion 111 of the motor case 10 is located at the position through which the straight line Lz1 passes, the breather 8 may penetrate the support wall portion 111. Also, if the peripheral wall portion 161 of the second case member 16 or the peripheral wall portion 171 of the cover member 17 is located at the position through which the straight line Lz1 passes, the breather 8 may penetrate these peripheral walls 161 and 171.

[0069] Furthermore, as shown in Figure 2, when viewed from the direction of the rotation axis X, the breather 8 is positioned along a straight line Lz2 that crosses the middle of the housing HS in the front-to-back direction in the vertical direction. The length from the straight line Lz2 in the front-to-back direction to the front surface HSe of the housing HS and the length to the back surface HSf of the housing HS are each half the total width W of the housing HS in the front-to-back direction (W / 2). In other words, the breather 8 is positioned in the center of the width direction when the direction perpendicular to the rotation axis X is defined as the width direction.

[0070] Here, it can be said that installing the breather 8 in a position that avoids the inverter INV makes it easier to attach to the housing HS. For example, it can be installed on the peripheral wall portion 121 of the cover member 12, or the peripheral wall portion 171 of the cover member 17, etc., in a position that avoids the inverter INV (breathers 8A and 8B shown by dashed lines in Figure 1).

[0071] However, a vehicle V equipped with drive unit 1 may experience the following driving conditions: (a) The vehicle V travels on an inclined surface (slope, bank, etc.). In this case, the position of the oil reservoir OT inside the housing HS changes as the vehicle V tilts. (b) The vehicle V turns a right or left curve. In this case, the position of the oil reservoir OT inside the housing HS changes due to the acceleration acting on the vehicle V in the lateral direction. (c) The vehicle V accelerates or decelerates rapidly. In this case, the position of the oil reservoir OT inside the housing HS also changes due to the acceleration acting on the vehicle V in the longitudinal direction. Therefore, depending on the position of the breather, the distance to the oil reservoir OT whose position has changed may become shorter. This can easily affect the breather's function of releasing air to the atmosphere.

[0072] The following explanation will use the case where the vehicle V described in (a) above travels on an inclined surface as an example, and will describe the positional relationship between the breather 8 and the oil reservoir OT in comparison with the positional relationship between the breathers 8A, 8B and the oil reservoir OT. Figure 3 is a diagram illustrating the vehicle V traveling on a horizontal road surface G. Figure 3 schematically shows the state of the vehicle V as viewed from the direction of the A-A arrow in Figure 2. Figure 4 is a diagram illustrating the oil reservoir OT inside the housing HS. Figure 4 schematically shows the state of the oil reservoir OT inside the housing HS when the vehicle V is in the posture shown in Figure 3. Note that in Figure 4, the motor 2 and power transmission mechanism 3 are omitted, and the external shape of the housing HS is schematically shown, in order to make the positional relationship between the breathers 8, 8A, 8B and the oil reservoir OT easier to understand.

[0073] As shown in Figure 3, in a vehicle V traveling on a road surface G along a horizontal line HL, the rotation axis X of the drive unit 1 is positioned parallel to the horizontal line HL. As shown in Figure 4, the oil reservoir OT within the housing HS of the drive unit 1 is formed at the bottom of the housing HS. The oil level OS of the oil reservoir OT is a flat surface below the rotation axis X, aligned with the horizontal line HL1.

[0074] In this state, the opening 811 of breather 8 faces the oil surface OS of the oil reservoir OT with a vertical gap of CL1. The opening 811A of breather 8A faces the oil surface OS with a vertical gap of CL2. The opening 811B of breather 8B faces the oil surface OS with a vertical gap of CL3.

[0075] Figure 5 illustrates a vehicle V traveling on an inclined surface G1. Figure 5 schematically shows the vehicle V as viewed from the front. Figure 6 illustrates an oil reservoir OT inside the housing HS. Figure 6 schematically shows the state of the oil reservoir OT inside the housing HS when the vehicle V is in the position shown in Figure 5.

[0076] As shown in Figure 5, the inclined surface G1 is tilted at an angle θ1 with respect to the horizontal line HL when viewed from the front of the vehicle. The inclined surface G1 is a bank that is tilted in such a way that the vertical height increases as you move from the right side (left side in the figure) to the left side (right side in the figure) of the vehicle V. In a vehicle V traveling on the inclined surface G1, the rotation axis X of the drive unit 1 is also tilted at an angle θ1 with respect to the horizontal line HL.

[0077] As shown in Figure 6, the right side HSc of the housing HS is located lower than the left side HSc in the direction of the rotation axis X. Consequently, the oil reservoir OT tends to be biased towards the right side HSc of the housing HS. The oil level OS of the oil reservoir OT is a flat surface along the horizontal line HL2 and intersects the rotation axis X. Although not shown in the figure, when the vehicle V turns a left curve, the centrifugal force tends to bias the oil reservoir OT towards the right side HSc of the housing HS.

[0078] In this state, the opening 811 of breather 8 faces the oil surface OS with a gap CL4 between them. The opening 811A of breather 8A faces the oil surface OS with a gap CL5 between them. The opening 811B of breather 8B faces the oil surface OS with a gap CL6 between them.

[0079] The distance CL4 between the opening 811 of breather 8 and the oil level OS is wider than the distance CL5 between the opening 811A of breather 8A and the oil level OS (CL4 > CL5). Also, the distance CL6 between the opening 811B of breather 8B and the oil level OS is wider than the distance CL4 between the opening 811 of breather 8 and the oil level OS (CL6 > CL4).

[0080] Therefore, (a) when vehicle V is traveling on an inclined surface G1 (see Figure 5), or (b) when vehicle V is turning a left curve, the gap CL5 between breather 8A and the oil surface OS among breathers 8, 8A, and 8B is significantly narrowed from the gap CL2 (see Figure 4) when traveling on a horizontal road surface G (CL5 < CL2). In these conditions, when the rotor core 21 of motor 2 (see Figure 1) rotates, the oil from the oil reservoir OT that is scooped up is more likely to enter breather 8A. As a result, the oil is more likely to be sprayed out of breather 8A.

[0081] Figure 7 illustrates a vehicle V traveling on an inclined surface G2. Figure 7 schematically shows the vehicle V as viewed from the front. Figure 8 illustrates an oil reservoir OT inside the housing HS. Figure 8 schematically shows the state of the oil reservoir OT inside the housing HS when the vehicle V is in the position shown in Figure 7.

[0082] As shown in Figure 7, the inclined surface G2 is tilted at an angle θ2 with respect to the horizontal line HL when viewed from the front of the vehicle. The inclined surface G2 is a bank that is tilted in such a way that the vertical height increases from the left side (right side in the figure) to the right side (left side in the figure) of the vehicle V. In a vehicle V traveling on the inclined surface G2, the rotation axis X of the drive unit 1 is also tilted at an angle θ2 with respect to the horizontal line HL.

[0083] As shown in Figure 8, the housing HS is positioned such that the left side HSd is lower than the right side HSc in the direction of the rotation axis X. Consequently, the oil reservoir OT tends to be biased towards the left side HSd of the housing HS. The oil level OS of the oil reservoir OT is a flat surface along the horizontal line HL3 and intersects the rotation axis X. Although not shown in the figure, when the vehicle V turns a right curve, the centrifugal force tends to bias the oil reservoir OT towards the left side HSd of the housing HS.

[0084] In this state, the opening 811 of breather 8 faces the oil surface OS with a gap CL7 between them. The opening 811A of breather 8A faces the oil surface OS with a gap CL8 between them. The opening 811B of breather 8B faces the oil surface OS with a gap CL9 between them.

[0085] The distance CL7 between the opening 811 of breather 8 and the oil level OS is wider than the distance CL9 between the opening 811B of breather 8B and the oil level OS (CL7 > CL9). Also, the distance CL8 between the opening 811A of breather 8A and the oil level OS is wider than the distance CL7 between the opening 811 of breather 8 and the oil level OS (CL8 > CL7).

[0086] Therefore, when (a) the vehicle V travels on an inclined surface G2 (see Figure 7), or (b) the vehicle V turns a right curve, the gap CL9 between the breather 8B and the oil surface OS is significantly narrowed compared to the gap CL3 (see Figure 4) when traveling on a level road surface G (CL9 < CL3). In these conditions, when the stepped pinion gear 53 and differential case 60 (see Figure 1) of the power transmission mechanism 3 rotate, the oil from the oil reservoir OT that is scooped up is more likely to enter the breather 8B. As a result, the oil is more likely to be sprayed out of the breather 8B.

[0087] Therefore, as shown in Figures 3 to 8, when comparing the positional relationship between the breathers 8, 8A, and 8B and the oil level OS, the breather 8, which is located in the middle of the housing HS in the direction of the rotation axis X, is able to maintain the position furthest from the oil level OS. As a result, by placing the breather 8 in the middle of the housing HS in the direction of the rotation axis X, it is made difficult for the oil from the oil reservoir OT that has been scraped up to enter the breather 8.

[0088] As a result, (a) when the vehicle V travels on an inclined surface (bank), or (b) when the vehicle V turns, the amount of oil ejected to the outside of the housing HS is reduced.

[0089] Furthermore, even when the breather 8 is provided in the middle of the housing HS in the direction of the rotation axis X, it can be provided on the front HSe side or the rear HSf side of the housing HS when viewed from the direction of the rotation axis X, as shown in Figure 2 (see breathers 8C and 8D shown by dashed lines in Figure 2).

[0090] Figure 9 illustrates a vehicle V traveling on an inclined surface G3. Figure 9 schematically shows the vehicle V as viewed from the left side. Figure 10 illustrates an oil reservoir OT inside the housing HS. Figure 10 schematically shows the state of the oil reservoir OT inside the housing HS when the vehicle V is in the position shown in Figure 9.

[0091] As shown in Figure 9, the inclined surface G3 is tilted at an angle θ3 with respect to the horizontal line HL when viewed from the left side of the vehicle. The inclined surface G3 is a downhill slope that slopes downwards from the rear side (right side in the figure) to the front side (left side in the figure) of the vehicle V. As the vehicle V descends the inclined surface G3, it tilts in a counterclockwise direction CCW around the point P where the inclined surface G3 and the drive wheels WH make contact, with the front side being lower than the rear side.

[0092] As shown in Figure 10, the housing HS is positioned so that the front HSe side is lower than the rear HSf side in the longitudinal direction. Consequently, the oil reservoir OT tends to be biased towards the front HSe side of the housing HS. The oil level OS of the oil reservoir OT is a flat surface along the horizontal line HL4. Although not shown in the figure, when the vehicle V decelerates rapidly, the oil reservoir OT tends to be biased towards the front HSe side of the housing HS due to inertial force.

[0093] In this state, the opening 811 of breather 8 faces the oil level OS of the oil reservoir OT with a gap CL10 between them. The opening 811C of breather 8C faces the oil level OS with a gap CL11 between them. The opening 811D of breather 8D faces the oil level OS with a gap CL12 between them.

[0094] The distance CL10 between the opening 811 of breather 8 and the oil level OS is wider than the distance CL11 between the opening 811C of breather 8C and the oil level OS (CL10 > CL11). Also, the distance CL12 between the opening 811D of breather 8D and the oil level OS is wider than the distance CL10 between the opening 811 of breather 8 and the oil level OS (CL12 > CL10).

[0095] Here, as shown in Figure 2, when viewed from the direction of the rotation axis X, if the vehicle V is traveling on a horizontal road surface G, the distance between the three breathers 8, 8C, and 8D and the oil reservoir OT is set to the same distance CL1.

[0096] In contrast, when (a) the vehicle V travels on an inclined surface G3 (see Figure 9), or (c) the vehicle V decelerates rapidly, as shown in Figure 10, the gap CL11 between the breather 8C and the oil surface OS among the breathers 8, 8C, and 8D is significantly narrowed from the gap CL1 (see Figure 2) when traveling on a horizontal road surface G (CL11 < CL1). In these conditions, when the rotor core 21 of the motor 2 (see Figure 1) rotates, the oil from the oil reservoir OT that is scooped up is more likely to enter the breather 8C. As a result, the oil is more likely to be sprayed out of the breather 8C.

[0097] Figure 11 illustrates a vehicle V traveling on an inclined surface G4. Figure 11 schematically shows the vehicle V as viewed from the left side. Figure 12 illustrates an oil reservoir OT inside the housing HS. Figure 12 schematically shows the state of the oil reservoir OT inside the housing HS when the vehicle V is in the position shown in Figure 11.

[0098] As shown in Figure 11, the inclined surface G4 is tilted at an angle θ4 with respect to the horizontal line HL when viewed from the left side of the vehicle. The inclined surface G4 is an uphill slope that is inclined in a direction where the height increases vertically from the rear side (right side in the figure) to the front side (left side in the figure) of the vehicle V. When the vehicle V goes up the inclined surface G4, it tilts clockwise CW around the point P where the inclined surface G4 and the drive wheels WH make contact, so that the rear side is lower than the front side.

[0099] As shown in Figure 12, the housing HS is positioned so that the rear HSf side is lower than the front HSe side in the front-rear direction. Consequently, the oil reservoir OT tends to be biased towards the rear HSf side of the housing HS. The oil level OS of the oil reservoir OT is a flat surface along the horizontal line HL5. Although not shown in the figure, when the vehicle V accelerates rapidly, the oil reservoir OT tends to be biased towards the rear HSf side of the housing HS due to inertial force.

[0100] In this state, the opening 811 of breather 8 faces the oil level OS of the oil reservoir OT with a gap CL13 between them. The opening 811C of breather 8C faces the oil level OS with a gap CL14 between them. The opening 811D of breather 8D faces the oil level OS with a gap CL15 between them.

[0101] The distance CL13 between the opening 811 of breather 8 and the oil level OS is wider than the distance CL15 between the opening 811D of breather 8D and the oil level OS (CL13 > CL15). Also, the distance CL14 between the opening 811C of breather 8C and the oil level OS is wider than the distance CL13 between the opening 811 of breather 8 and the oil level OS (CL14 > CL13).

[0102] Therefore, (a) when the vehicle V travels on an inclined surface G4 (see Figure 11), or (c) when the vehicle V accelerates rapidly, as shown in Figure 12, the gap CL15 between the breather 8D and the oil surface OS among the breathers 8, 8C, and 8D is significantly narrowed from the gap CL1 (see Figure 2) when traveling on a horizontal road surface G (CL15 < CL1). When the rotor core 21 of the motor 2 (see Figure 1) rotates in these conditions, the oil from the oil reservoir OT that has been scooped up is more likely to enter the breather 8D. As a result, the oil is more likely to be sprayed out of the breather 8D.

[0103] Therefore, as shown in Figures 9 to 12, when comparing the positional relationship between the breathers 8, 8C, 8D and the oil level OS with respect to the inclination of the vehicle V, the breather 8, which is located in the middle of the housing HS in the longitudinal direction, is able to maintain the position furthest from the oil level OS. As a result, by placing the breather 8 in the middle of the housing HS in the longitudinal direction, it is difficult for the oil from the oil reservoir OT that has been scraped up to enter the breather 8.

[0104] As a result, (a) when the vehicle V travels on an inclined surface (uphill or downhill), or (c) when the vehicle V accelerates or decelerates rapidly, the amount of oil discharged to the outside of the housing HS is reduced.

[0105] In this embodiment, the breather 8 is exemplified as being positioned midway along the housing HS in the direction of the rotation axis X (on the straight line Lz1 in Figure 1) and midway along the front-rear direction (on the straight line Lz2 in Figure 2). However, the position of the breather 8 is not limited to this embodiment. It may be positioned at a location offset from the straight lines Lz1 and Lz2, as long as it is within a predetermined range including the straight lines Lz1 (see Figure 1) and Lz2 (see Figure 2).

[0106] Figures 13 and 14 illustrate the installation range of the breather in the housing HS. Figure 13 schematically shows the housing HS mounted on a vehicle V as viewed from the front of the vehicle. In Figure 13, the housing HS tilted in the direction shown in Figure 6 is shown with a solid line, and the housing HS tilted in the direction shown in Figure 8 is shown with a dashed line, and they are superimposed with the oil level OS aligned. Figure 14 schematically shows the housing HS mounted on a vehicle V as viewed from the left side of the vehicle. In Figure 14, the housing HS tilted in the direction shown in Figure 10 is shown with a solid line, and the housing HS tilted in the direction shown in Figure 12 is shown with a dashed line, and they are superimposed with the oil level OS aligned. In the following explanation, the housing HS shown with dashed lines will be denoted with an apostrophe (') next to the symbols of each part.

[0107] As shown in Figures 13 and 14, whether the housing HS is tilted in the direction indicated by the solid line in the figure, or the housing HS' is tilted in the direction indicated by the dashed line, the oil level OS of the oil reservoir OT is a flat surface along the horizontal line HL.

[0108] Therefore, by providing a breather 8 in both housing HS and HS' in a region facing the oil surface OS with a predetermined gap CLs between them, a gap CLs is ensured between the breather 8 and the oil surface OS even if the housing HS is tilted. Here, the predetermined gap CLs can be determined by simulation based on the expected tilt of the housing HS during driving, the shape of the housing HS, and the amount of oil stored in the housing HS.

[0109] As shown in Figure 13, the horizontal line HLa, which passes above the oil level OS by a distance CLs, intersects the upper surfaces HSa and HSa' of the inclined housings HS and HS'. ​​In housing HS, the horizontal line HLa intersects the upper surface HSa to the right of the breather 8 (intersection q1). In housing HS', the horizontal line HLa intersects the upper surface HSa' to the left of the breather 8' (intersection q2).

[0110] The region Ra between the intersection points q1 and q2 in the rotation axis X direction is a region that includes the straight line Lz1 (see Figure 1), and is also a region in which at least a gap CLs is always ensured between the openings 811 and 811', which are the inlets of the breathers 8 and 8', and the oil surface OS in both housings HS and HS'.

[0111] Therefore, even if the breather 8 is located at a position offset from the midpoint of the housing HS in the direction of the rotation axis X (on the straight line Lz1 in Figure 1), as long as it is within region Ra, at least a gap CLs can be secured between it and the oil surface OS. In other words, the range defined by region Ra corresponds to the central part of the housing HS in the direction of the rotation axis X.

[0112] Furthermore, as shown in Figure 14, when viewed from the direction of the rotation axis X, the horizontal line HLa intersects the upper surface HSa at the front of the breather 8 (intersection q3). Also, in the housing HS', the horizontal line HLa intersects the upper surface HSa' at the rear of the breather 8' (intersection q4).

[0113] The region Rb between the intersection points q3 and q4 in the front-rear direction is a region that includes the straight line Lz2 (see Figure 2), and is also a region in which at least a gap CLs is always ensured between the openings 811 and 811', which are the inlets of the breathers 8 and 8', and the oil surface OS in both housings HS and HS'.

[0114] Therefore, even if the breather 8 is located off-center from the middle of the housing HS in the longitudinal direction (on the straight line Lz2 in Figure 2), as long as it is within region Rb, it can maintain a minimum distance CLs between itself and the oil surface OS. In other words, the area defined by region Rb corresponds to the central part of the housing HS in the longitudinal direction.

[0115] A particularly large amount of oil enters through the opening 811, which is the inlet of the breather 8. For this reason, as in the embodiment, it is especially preferable to position the opening 811 of the breather 8 in the center in the direction of the rotation axis X and / or the width direction. In addition, oil may also enter the breather 8 from paths other than the opening 811, for example, by leakage. For this reason, it is also preferable to position the entire breather 8, not limited to the opening 811, in the center in the direction of the rotation axis X and / or the width direction.

[0116] The following are examples of a drive unit 1 in a certain aspect of the present invention. (1) It has a housing HS that houses a motor 2, a power transmission mechanism 3 connected downstream of the motor 2, and a drive shaft 7 (shaft) connected downstream of the power transmission mechanism 3 and passing through the motor 2 and the power transmission mechanism 3. An oil reservoir OT is formed inside the housing HS in which the motor 2 and the power transmission mechanism 3 are submerged. In the vertical direction with respect to the state in which the housing HS is mounted on a vehicle, a breather 8 is arranged at the top of the housing HS. The breather 8 is arranged on a straight line Lz1 passing through the axial center of the housing HS when the axial direction is considered to be parallel to the rotation axis X of the motor 2.

[0117] According to the embodiment, as shown in Figure 13, for example, even if the drive unit 1 is tilted significantly in either direction in the rotation axis X, the distance between the oil reservoir OT and the opening 811 (breather inlet) of the breather 8 will be maintained at a certain level or higher (for example, a gap of CLs or more). Furthermore, even if acceleration in the left-right direction acts on the drive unit 1, the distance between the oil reservoir OT and the opening 811 (breather inlet) of the breather 8 will be maintained at a certain level or higher (for example, a gap of CLs or more). Therefore, the amount of oil discharged to the outside of the housing HS can be reduced. The axial center portion is a predetermined range (region Ra, see Figure 13) that includes a straight line Lz1 passing midway between the right side surface HSc, which is one end of the housing HS in the rotation axis X direction, and the left side surface HSd, which is the other end.

[0118] (2) The breather 8 is positioned on a straight line Lz2 that passes through the center of the front-rear direction (center of the width direction) when the direction perpendicular to the rotation axis X is defined as the front-rear direction of the vehicle V (width direction of the housing).

[0119] According to the embodiment, as shown in Figure 14, for example, even if the drive unit 1 is tilted significantly in either the front-rear or rear-facing direction, the distance between the oil reservoir OT and the opening 811 (breather inlet) of the breather 8 will be maintained at a certain level or higher (for example, a gap of CLs or higher). Furthermore, even if acceleration in the front-rear direction acts on the drive unit 1, the distance between the oil reservoir OT and the opening 811 (breather inlet) of the breather 8 will be maintained at a certain level or higher (for example, a gap of CLs or higher). Therefore, the amount of oil discharged to the outside of the housing HS can be reduced. The widthwise central portion is a predetermined range (region Rb, see Figure 14) that includes a straight line Lz2 passing midway between the front HSe, which is one end of the housing HS in the front-rear direction, and the rear HSf, which is the other end.

[0120] (Modification) In the above-described embodiment, as shown in Figures 1 and 2, the entire breather 8 is positioned in the center of the housing HS in the direction of the rotation axis X and in the front-rear direction (width direction). However, the embodiment is not limited to this. It is sufficient that at least a part of the breather 8 is positioned in the center of the rotation axis X and in the width direction.

[0121] Figure 15 is a diagram illustrating a modified drive unit 1A. Figure 16 is a diagram illustrating a modified drive unit 1A. Figure 16 schematically shows the drive unit 1A as viewed from the direction of the A-A arrow in Figure 15. As shown in Figure 15, in the modified drive unit 1A, a communication passage Ha is provided in the gear case 14A that connects the inside and outside of the housing HS.

[0122] The connecting passage Ha is located in the upper part of the housing HS and below the inverter INV in the vertical direction. The connecting passage Ha has a first passage Ha1 oriented along a straight line Lz1, and a second passage Ha2 that connects to the upper end of the first passage Ha1 and is oriented along the rotation axis X. As shown in Figure 16, when viewed from the direction of the rotation axis X, the first passage Ha1 is oriented along a straight line Lz2. Note that Figure 15 shows a linear connecting passage Ha, but the configuration is not limited to this. For example, the connecting passage Ha may have a labyrinth structure to obstruct the flow of infiltrated oil.

[0123] As shown in Figure 15, the lower end of the first passage Ha1 opens into the motor room Sa. The end of the second passage Ha2 opposite to the first passage Ha1 is connected to the breather pipe 81 of the breather 8A. The breather 8A may not have a breather pipe 81. For example, a filter 80 may be directly provided in the second passage Ha2.

[0124] As a result, the pressure built up within the housing HS is taken in from the first passage Ha1 to the connecting passage Ha and released to the atmosphere from the breather 8. In the modified drive unit 1A, the first passage Ha1, which is the breather inlet of the breather 8A, is located in the central part of the housing HS in the direction of the rotation axis X (see Figure 15) and in the central part in the front-rear direction (see Figure 16). Therefore, even if the housing HS is tilted, it is difficult for oil to enter the connecting passage Ha. As a result, the amount of oil discharged to the outside of the housing HS can be reduced.

[0125] In the embodiments and modifications described above, examples were given in which the breathers 8 and 8A are in contact with the motor chamber Sa. However, the invention is not limited to this embodiment. For example, if the internal space of the inverter INV (inverter chamber) is in communication with the motor chamber Sa and the gear chamber Sb, the breather 8 may be provided on the upper surface of the inverter INV to connect with the inverter chamber. In this case, the upper surface of the inverter INV constitutes the upper surface HSa of the housing HS. As the distance between the opening 811 of the breather 8 and the oil surface OS becomes wider, the area defined as the central part of the housing HS (regions Ra, Rb) is expanded.

[0126] In this embodiment, a breather 8 is provided in a single-axis drive unit 1 in which the rotation axes of the first planetary gear 4, the second planetary gear 5, and the differential mechanism 6, and the axes of the drive shafts 7 (7A, 7B) are arranged coaxially with the rotation axis X of the motor 2 (see Figure 1). However, the invention is not limited to this embodiment. The present invention can also be applied to a two-axis drive unit in which, for example, a counter gear (not shown) is interposed between the motor 2 and the differential mechanism 6 instead of the first planetary gear 4 and the second planetary gear 5. In a two-axis drive unit, the counter gear rotates around an axis parallel to the rotation axis X. In such a two-axis drive unit, the same effects as in the above embodiment can be achieved by providing the breather 8 in the axial center.

[0127] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments shown. It can be modified as appropriate within the scope of the technical idea of ​​the invention.

[0128] 1, 1A: Drive unit, 2: Motor, 3: Power transmission mechanism, 7 (7A, 7B): Drive shaft (shaft), 8: Breather, 811: Opening, CL1-CL15, CLs: Spacing, G: Road surface, G1-G4: Inclined surface, HL: Horizontal line, HS: Housing, HSa: Top surface, HSc: Right side, HSd: Left side, HSe: Front, HSf: Rear, INV: Inverter, Lz1: Straight line passing through the axial center, Lz2: Straight line passing through the front-rear (width direction) center, OS: Oil level, OT: Oil reservoir, V: Vehicle, X: Rotating axis

Claims

1. A drive unit having a housing that houses a motor, a power transmission mechanism connected downstream of the motor, and a shaft connected downstream of the power transmission mechanism and passing through the motor and the power transmission mechanism, wherein an oil reservoir is formed inside the housing in which the motor and the power transmission mechanism are immersed, and a breather is positioned at the upper part of the housing and in the axial center of the housing when the direction parallel to the rotation axis is considered as the axial direction.

2. The breather according to claim 1, wherein the breather is a drive unit located in the center of the width direction when the direction perpendicular to the rotation axis is defined as the width direction.

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