Vehicle drive unit and saddle-riding type electric vehicle

Abstract

To provide a vehicle drive unit which cools an oil circulating in an oil passage to inhibit a shortage of an oil film or wear of a slide part of a bearing.SOLUTION: A vehicle drive unit 10 includes a motor housing 20, a motor 30, a bearing 24, a gear 35, a gear housing 40 which is connected to the motor housing 20 and in which an oil reservoir 45 for storing an oil is formed at a bottom part, a speed reduction mechanism which is housed in the gear housing 40 and reduces a speed of rotation of the gear 35 and transmits the rotation to an output shaft 52; and an oil passage which is formed at the motor housing 20 to guide the oil stored in the oil reservoir 45 to the bearing 24. The motor housing 20 is provided with an external passage for circulating outside air at the outside of the motor housing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive unit that transmits rotation of a motor to wheels via gears and a reduction mechanism, and to a straddle-type electric vehicle that uses the drive unit. [Background technology]

[0002] In a vehicle driven by a motor, the rotation of the motor is transmitted to the wheels via gears and a reduction mechanism. In this case, to properly lubricate the bearings that rotatably support the motor shaft, oil is stored at the bottom of the housing and then scooped up by multiple gears and supplied to the bearings.

[0003] For example, Patent Document 1 below describes an axle device that has a housing for storing oil, a large gear and a pinion gear housed in the housing, and an oil tank located above the center of rotation of the large gear, the oil tank having a first guide side wall facing the outer periphery of the large gear and a second guide side wall facing the inner wall surface of the housing. The housing is configured so that a motor housing that houses a motor and a gear housing that houses the large gear and the pinion gear are connected together.

[0004] The oil supplied to the oil tank on the gear housing side passes through a passage formed above the motor housing and extending in the axial direction of the motor shaft, and drips onto the bearing that supports the rotation of the motor shaft at a position away from the gear housing, lubricating the bearing. After lubricating the bearing, the oil falls to the bottom of the motor housing and flows to the bottom of the gear housing, where it is scooped up again by the large gear, allowing the oil to circulate within the gear housing and motor housing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-172994 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the oil circulating inside the housing gradually becomes hotter. In this case, the viscosity of the oil decreases, raising concerns about the oil film breakdown and wear on the sliding parts of the bearings on the motor shaft. However, the axle device described in Patent Document 1 does not disclose any measures to address these concerns.

[0007] Therefore, an object of the present invention is to provide a vehicle drive unit and a saddle-type electric vehicle that can cool oil circulating through an oil passage and suppress oil film breakdown and wear on the sliding parts of the bearing. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a drive unit for a vehicle comprising: a motor housing; a motor housed within the motor housing and having a stator, a rotor rotatably arranged inside the stator, and a shaft connected to the central axis of the rotor; a bearing rotatably supporting one axial end of the shaft and held in the motor housing; a gear connected to the other axial end of the shaft; a gear housing connected to the motor housing and having an oil reservoir at the bottom for storing oil; a reduction mechanism housed within the gear housing and reducing the rotation of the gear before transmitting it to an output shaft; and an oil passage formed in the motor housing so as to guide the oil stored in the oil reservoir to the bearing, wherein the motor housing is provided with an outside air passage for circulating outside air outside the motor housing.

[0009] According to the above invention, the outside air outside the motor housing flows through the outside air passage, which cools the motor housing and at the same time cools the oil in the oil passage formed in the motor housing, thereby suppressing oil film breakdown and wear on the sliding parts of the bearing due to a decrease in oil viscosity.

[0010] In the drive unit of a vehicle according to the present invention, the motor housing may have a circumferential wall that covers the radial outside of the motor in a circumferential direction of the motor, the oil passage may have an axial oil passage formed in the circumferential wall and extending in the axial direction of the motor, and the outside air passage may have a circumferential outside air passage arranged outside the circumferential wall.

[0011] According to the above aspect, the outside air passage has a circumferential outside air passage that is arranged outside the circumferential wall, and by having outside air flow through this circumferential outside air passage, the oil in the axial oil passage can be efficiently cooled via the circumferential wall.

[0012] In the drive unit of a vehicle according to the present invention, in a cross section taken along a plane perpendicular to the axial direction of the motor, the circumferential outside air passage may be arranged on an extension of a straight line connecting an outer periphery of the axial oil passage and an outer periphery of the circumferential wall by the shortest distance.

[0013] According to the above aspect, since the circumferential outside air passage has the above layout, the distance between the axial oil passage and the circumferential outside air passage can be shortened, and the cooling efficiency of the oil in the axial oil passage can be further improved by the flow of outside air through the circumferential outside air passage.

[0014] In the drive unit of a vehicle according to the present invention, the motor housing may have an axial end wall located on one axial end side of the motor, the oil passage may have a radial oil passage formed in the axial end wall and extending radially of the motor, and the outside air passage may have an end outside air passage arranged outside the axial end wall.

[0015] According to the above aspect, the outside air passage has an end outside air passage arranged outside the axial end wall, so that outside air circulating through this end outside air passage can efficiently cool the oil in the radial oil passage via the axial end wall.

[0016] The drive unit of the vehicle according to the present invention may be configured to include a fan connected to one axial end of the shaft and rotating in conjunction with the shaft, and the outside air is supplied to the outside air passage by the rotation of the fan.

[0017] According to the above aspect, the rotation of the fan causes outside air to be supplied to the outside air passage, so that the oil circulating in the motor housing and the oil passage can be effectively cooled by this outside air.

[0018] In the drive unit of a vehicle according to the present invention, a shroud that directs fluid flow in one direction is arranged around the fan, and the rotation of the fan may be configured to guide outside air within the shroud into the outside air passage.

[0019] According to the above aspect, the shroud arranged around the fan guides the outside air inside the shroud into the outside air passage, so that the motor housing and the oil circulating inside the oil passage can be effectively cooled.

[0020] The drive unit of a vehicle according to the present invention includes a fan connected to one axial end of the shaft and rotating in conjunction with the shaft, and is configured so that the outside air is supplied to the outside air passage by the rotation of the fan, and a shroud that directs fluid to flow in one direction is arranged around the fan, and is configured so that the outside air inside the shroud is led to the outside air passage by the rotation of the fan, the shroud is case-shaped and separates an internal space from an external space, and the end outside air passage may be formed inside the shroud.

[0021] According to the above aspect, an end outside air passage is formed inside the case-shaped shroud that separates the internal space from the external space, so that outside air generated by the rotation of the fan can reliably circulate through the end outside air passage inside the shroud, thereby effectively cooling the axial end wall and the inside of the oil passage.

[0022] In the drive unit of a vehicle according to the present invention, the end-side outside air passage may be formed inside the shroud, and a cover-shaped cover member that separates an internal space from an external space may be arranged on the outer periphery of the circumferential wall, and the circumferential outside air passage may be formed inside the cover member, and the circumferential outside air passage may be configured to communicate with the end-side outside air passage formed inside the shroud.

[0023] According to the above aspect, the circumferential outside air passage formed inside the cover member and the end side outside air passage formed inside the shroud are configured to be connected to each other, so that the outside air that has circulated through the end side outside air passage inside the shroud can reliably circulate to the circumferential outside air passage inside the cover member, thereby making it possible to cool the inside of the oil passage even more effectively.

[0024] In the vehicle drive unit according to the present invention, fins may be formed on an outer periphery of the motor housing, the fins extending toward the outside air passage.

[0025] According to the above aspect, fins extending toward the outside air passage are formed on the outer periphery of the motor housing, so that the heat dissipation area of ​​the motor housing can be increased by the amount of the fins, thereby improving both the cooling ability of the motor housing by the outside air flowing through the outside air passage and the cooling ability of the oil in the oil passage formed in the motor housing.

[0026] In the drive unit of the vehicle of the present invention, the reduction mechanism may have a plurality of gears that can scoop up the oil in the oil reservoir, and an oil receiving portion may be provided inside the gear housing above the bearing, and the oil scooped up from the oil reservoir by the plurality of gears may be supplied to the oil receiving portion, and the oil supplied to the oil receiving portion may be supplied to the bearing via the axial oil passage and the radial oil passage.

[0027] According to the above aspect, the oil stored in the oil reservoir is supplied to the oil receiving section by the multiple gears of the reduction mechanism, and the oil supplied to the oil receiving section is supplied to the bearing via the axial oil passage and the radial oil passage. Therefore, the oil in the oil reservoir can be supplied to the bearing without using an oil pump, thereby simplifying the structure and reducing the number of parts.

[0028] In the drive unit of a vehicle according to the present invention, the motor housing may have a bearing holder formed on the axial end wall for holding the bearing, a plurality of ribs extending radially outward from the outer periphery of the bearing holder, one of which rib extending toward the axial oil passage to form the radial oil passage, and the oil flowing through the axial oil passage may be supplied to the bearing along the rib.

[0029] According to the above aspect, the rigidity of the axial end wall and the bearing holder can be improved by the multiple ribs extending from the outer periphery of the bearing holder, and one of the ribs also serves as a radial oil passage, which allows for simplification and miniaturization of the motor housing.

[0030] In the drive unit of the vehicle of the present invention, a notch that connects the radial oil passage and the bearing is formed in a part of the circumference of the bearing holder, and the oil circulating along the rib may be supplied to the bearing through the notch.

[0031] According to the above aspect, a notch is formed in a portion of the circumference of the bearing holder to connect the radial oil passage with the bearing, and oil flowing along the rib is supplied to the bearing through the notch, so that the notch ensures that oil is supplied to the bearing.

[0032] On the other hand, a straddle-type electric vehicle according to the present invention is characterized in that it is equipped with the drive unit of the above-mentioned vehicle.

[0033] According to the above invention, a saddle-type electric vehicle that is equipped with a vehicle drive unit having the above configuration can be provided, which saves space and reduces costs. In other words, the vehicle drive unit installed in a saddle-type electric vehicle according to the present invention can cool oil with a simple configuration without using an oil cooler or the like, and is therefore particularly effective when installed in a saddle-type electric vehicle (two-wheeled vehicle), which requires low cost and has difficulty in securing installation space for a drive unit compared to a four-wheeled vehicle.

[0034] Furthermore, compared to four-wheeled vehicles, vehicle mounted parts in a saddle-ride type electric vehicle are more likely to be exposed to outside air. Therefore, when the vehicle drive unit according to the present invention is mounted on a saddle-ride type electric vehicle, the motor housing can be exposed to outside air directly without using a special passage or the like for guiding air, and the oil can be cooled with a small, inexpensive configuration. [Effects of the Invention]

[0035] In the present invention, outside air from outside the motor housing flows through the outside air passage, which cools the motor housing and at the same time cools the oil in the oil passage formed in the motor housing, thereby suppressing oil film breakdown and wear on the sliding parts of the bearing due to a decrease in oil viscosity. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a plan view showing an embodiment of a vehicle drive unit according to the present invention; [Figure 2] 3 is an explanatory diagram of the drive unit when viewed from the reducer side with a part of the gear housing removed. FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along the line BB in FIG. [Figure 5] FIG. 2 is a cross-sectional view taken along the line CC in FIG. [Figure 6] FIG. 2 is a cross-sectional view taken along the line DD in FIG. [Figure 7]5 is a cross-sectional view taken along the line EE in FIG. 4. [Figure 8] 1 is a perspective view showing an embodiment of a saddle-type electric vehicle according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0037] (One embodiment of a vehicle drive unit) Hereinafter, one embodiment of a vehicle drive unit according to the present invention will be described with reference to FIGS.

[0038] As shown in Figures 1 to 3, the drive unit 10 of the vehicle of this embodiment (hereinafter also simply referred to as "drive unit 10") is mainly composed of a motor housing 20, a motor 30 accommodated in the motor housing 20, a gear housing 40 connected to the motor housing 20, a reduction mechanism consisting of a plurality of gears 50, 51, a fan 65 linked to the shaft 33 of the motor 30, and a cover member 70 and a shroud 75 arranged on the outside of the motor housing 20.

[0039] 8, the drive unit 10 is mounted on a saddle-type electric vehicle 100 (hereinafter also simply referred to as "vehicle 100"). In the following description, the front-to-rear direction of the vehicle 100 is referred to as the "X direction," the left-to-right direction of the vehicle 100 that is perpendicular to the X direction is referred to as the "Y direction," and the up-down direction of the vehicle 100 that is perpendicular to the X direction and the Y direction is referred to as the "Z direction."

[0040] 3, the motor 30 has a stator 31, a rotor 32 rotatably disposed inside the stator 31, and a shaft 33 coupled to the central axis of the rotor 32. The axial directions of the shaft 33 and the motor 30 are parallel to the Y direction of the vehicle 100. One axial end 33a of the shaft 33 is rotatably supported by a bearing 24. A gear 35 is connected to the other axial end 33b of the shaft 33.

[0041] An oil reservoir 45 capable of storing oil is formed at the bottom of the gear housing 40 that constitutes the drive unit 10. Meanwhile, an oil passage is formed in the motor housing 20 to guide the oil to the bearing 24. As shown in Figure 4, the oil passage in this embodiment consists of an axial oil passage 55 and a radial oil passage 56.

[0042] An outside air passage for circulating outside air outside the motor housing is formed in the motor housing 20. In this embodiment, the outside air passage is formed inside the cover member 70 and the shroud 75, and is composed of a circumferential outside air passage 60 and an end outside air passage 61, as shown in FIG.

[0043] Furthermore, a fan 65, such as a sirocco fan, is connected to one axial end 33a of the shaft 33. The fan 65 rotates in conjunction with the rotation of the shaft 33. The rotation of the fan 65 causes outside air outside the motor housing to be supplied to the outside air passage.

[0044] Next, the motor housing 20 will be described in detail. The motor housing 20 has a curved circumferential wall 21 that covers the radially outer side of the stator 31 of the motor 30 in the circumferential direction of the motor 30, and an axial end wall 22 that is located on one axial end side of the motor 30.

[0045] 3, a shaft insertion hole 23a is formed in the center of the axial end wall 22, and a substantially cylindrical bearing holder 23 protrudes toward the inside of the motor housing around the shaft insertion hole 23a on the inner surface of the axial end wall 22. A bearing 24 that rotatably supports one end 33a of a shaft 33 is housed and held in the bearing holder 23.

[0046] 7, a plurality of ribs 25 extend radially outward from the outer periphery of the bearing holder 23 formed on the axial end wall 22, and the tip end of each rib 25 in the extending direction is connected to the inner periphery of the circumferential wall 21. Note that one of the plurality of ribs 25, rib 25a, forms a radial oil passage 56 (see FIG. 7).

[0047] In addition, a notch 23b that connects the radial oil passage 56 and the bearing 24 is formed in a portion of the circumference of the bearing holder 23, specifically in a position close to the rib 25a in the circumference of the bearing holder 23.

[0048] Furthermore, as shown in FIG. 3, a plurality of fins 26 are provided on the outer peripheral portion 21a located above the circumferential wall 21 in the Z direction and inside the cover member 70, extending (standing upright) toward the circumferential outside air passage 60, which is an outside air passage, and extending in the X direction.

[0049] Next, the gear housing 40 will be described in detail. The gear housing 40 has an outer wall 41 that covers the radial outside of the multiple gears 50, 51 that make up the reduction mechanism, an axial end wall 42 that is located on one end side of the outer wall 41 and on the other axial end side of the motor 30, and a partition wall 43 that is located on the other end side of the outer wall 41, opposite the axial end wall 42. As shown in Figure 4, a space surrounded by lower end portions in the Z direction of the outer wall 41, the axial end wall 42, and the partition wall 43 forms an oil reservoir 45.

[0050] The other end of the outer wall 41 (the end opposite the axial end wall 42) and the other end of the circumferential wall 21 of the motor housing 20 (the end opposite the axial end wall 22) are connected to each other, thereby integrating the gear housing 40 and the motor housing 20 and forming two internal spaces via the partition 43.

[0051] 4, an oil reservoir 27 is also formed in the lower end portion in the Z direction of the circumferential wall 21 of the motor housing 20, in a position close to the partition wall 43. This oil reservoir 27 on the motor housing 20 side is in communication with the oil reservoir 45 on the gear housing 40 side via a communication hole or the like (not shown).

[0052] Returning to the explanation of the gear housing 40, as shown in Fig. 3, substantially cylindrical bearing holders 42a, 43a are formed in the axial end wall 42 and the partition wall 43, respectively. A bearing 42b that rotatably supports the other axial end 33b of the shaft 33 is disposed in the bearing holder 42a, and a bearing 43b that rotatably supports an intermediate portion of the shaft 33 in the axial direction is disposed in the bearing holder 43a.

[0053] 2, a small-diameter gear 50 that meshes with gear 35 fixed to shaft 33, and a gear 51 that is larger in diameter than gear 50 and meshes with gear 50 are disposed inside gear housing 40, and these gears 50, 51 form a speed reduction mechanism. This speed reduction mechanism reduces the rotational speed of shaft 33 and also scoops up oil stored in oil reservoir 45.

[0054] The large diameter gear 51 is fixed to an output shaft 52. When the motor 30 rotates, the output shaft 52 rotates via a speed reduction mechanism.

[0055] 2, an oil receiving portion 46 is provided above the bearing 42b inside the gear housing 40. The oil receiving portion 46 in this embodiment is disposed above the bearings 24, 42b, gear 35, and gear 50 and on the circumferential outside of gear 51, and has a generally inclined L-shaped frame shape made up of a vertical wall and a horizontal wall extending obliquely upward from the lower end of the vertical wall.

[0056] The oil scooped up from oil reservoir 45 toward the top of the housing by the multiple gears 50, 51 is supplied to oil receiving portion 46 and stored therein. The oil supplied to oil receiving portion 46 is also configured to be supplied to bearing 24 via axial oil passage 55 and radial oil passage 56 (see arrows in FIG. 4). Although bearing 24 is not shown in FIG. 4 due to the cutout location, oil is supplied to bearing 24 held in bearing holder 23.

[0057] Next, the oil passage and the outside air passage, as well as the members that form these passages, will be described in detail.

[0058] 4, an axial oil passage 55, which is one of the oil passages, is formed in the circumferential wall 21 of the motor housing 20 and extends in the axial direction of the motor 30. Specifically, the axial oil passage 55 is disposed radially above the circumferential wall 21, and its axial base end communicates with the internal space of the oil receiving portion 46 provided in the gear housing 40, extending along the Y direction.

[0059] Further, the radial oil passage 56 is formed in the axial end wall 22 of the motor housing 20 and extends in the radial direction of the motor 30. Specifically, as shown in Figure 7, one of the plurality of ribs 25 formed in the axial end wall 22 of the motor housing 20 described above, rib 25a extending obliquely outward toward the circumferential wall 21, forms the radial oil passage 56.

[0060] The oil flowing through the axial oil passage 55 flows along the rib 25a forming the radial oil passage 56 and passes through the notch 23b to be supplied to the bearing 24 (see the arrow in FIG. 7).

[0061] As shown in FIG. 4, a return oil passage 57 extends radially downward from the circumferential wall 21 of the motor housing 20 to return the oil supplied to the bearing 24 to the oil reservoir 27 on the motor housing 20 side.

[0062] The outside air passage is composed of a circumferential outside air passage 60 arranged outside the circumferential wall 21 of the motor housing 20 and an end outside air passage 61 arranged outside the axial end wall 22 of the motor housing 20, and each passage 60, 61 is formed inside the cover member 70 and the shroud 75.

[0063] The cover member 70 is formed in a cover shape on the outer periphery of the circumferential wall 21 of the motor housing 20 so as to separate the interior space from the exterior space.

[0064] The cover member 70 of this embodiment is composed of a pair of side walls 71, 71 that extend circumferentially around the circumferential wall 21 and are arranged at a predetermined interval in the Y direction, and a peripheral wall 72 that connects the tips of the pair of side walls 71, 71. The circumferential outside air passage 60 is formed inside the cover member 70, i.e., inside the pair of side walls 71, 71 and the peripheral wall 72.

[0065] 6, in a cross section taken along a plane perpendicular to the axial direction of the motor 30, the circumferential outside air passage 60 is disposed on an extension line L of a straight line connecting, at the shortest distance, the outer periphery 55a of the axial oil passage 55 and the outer periphery 21a of the circumferential wall 21 of the motor housing 20. Furthermore, the circumferential outside air passage 60 is configured to communicate with an end outside air passage 61 formed inside the shroud 75.

[0066] On the other hand, the shroud 75 is shaped like a case that separates the internal space from the external space, and is arranged around the fan 65 to direct and circulate fluids such as air in one direction. The shroud 75 is configured so that the rotation of the fan 65 guides the outside air inside the shroud 75 into the outside air passage.

[0067] 3 and 4, the shroud 75 of this embodiment is composed of a substantially cylindrical peripheral wall 76 that protrudes from the outer surface of the axial end wall 22 of the motor housing 20 so as to cover the fan 65, an end wall 77 that is located at the tip of the peripheral wall 76 in the protruding direction, and an extension portion 78 that extends from the lower circumferential end portion of the peripheral wall 76 along the outside of the lower end portion of the circumferential wall 21 of the motor housing 20. An end outside air passage 61 is formed inside the shroud 75, i.e., inside the peripheral wall 76, end wall 77, and extension portion 78.

[0068] The end wall 77 is also formed with an outside air inlet 77a for introducing outside air from outside the motor housing into the fan 65. The end outside air passage 61 is configured to communicate with the circumferential outside air passage 60 formed inside the cover member 70.

[0069] (Action and effect) Next, the effects of the drive unit 10 having the above configuration will be described.

[0070] When the motor 30 rotates due to an external power source or the like (not shown), the gear 35 connected to the other end 33b of the shaft 33 rotates the small-diameter gear 50, which in turn rotates the large-diameter gear 51, causing the output shaft 52 to rotate, thereby rotating the wheels 110 of the vehicle 100 via a sprocket, chain, or the like (not shown).

[0071] Furthermore, as the gears 50 and 51 rotate, the oil stored in the oil reservoir 45 is scooped up toward the top of the gear housing and supplied to the oil receiving portion 46. The oil supplied to the oil receiving portion 46 flows through the axial oil passage 55, along the rib 25a forming the radial oil passage 56, and through the notch 23b of the bearing holder 23 to be supplied to the bearing 24 that rotatably supports the one end 33a of the shaft 33. As a result, the bearing 24 is lubricated.

[0072] Furthermore, the oil supplied to the bearing 24 flows through the return oil passage 57 and is returned to the oil reservoir 27 on the motor housing 20 side, and the oil returned to this oil reservoir 27 flows to the oil reservoir 45 on the gear housing 40 side through a communication hole or the like (not shown).

[0073] Therefore, the oil circulates in the following order: oil reservoir 45 on the gear housing 40 side, gears 50, 51, oil receiving portion 46, axial oil passage 55, radial oil passage 56, bearing 34, return oil passage 57, and oil reservoir 27 on the motor housing 20 side.

[0074] In addition, as the fan 65 rotates in conjunction with the rotation of the shaft 33 of the motor 30, outside air is introduced into the fan 65 through the outside air inlet 77a, and the rotation of the fan 65 causes outside air to circulate within the end outside air passage 61 within the shroud 75, and also causes outside air to circulate within the circumferential outside air passage 60 within the cover member 70 which is connected to the end outside air passage 61.

[0075] In this drive unit 10, the outside air outside the motor housing flows through the outside air passage, which cools the motor housing 20 and also cools the oil in the oil passage formed in the motor housing 20, thereby preventing oil film breakdown and wear on the sliding parts of the bearings due to a decrease in oil viscosity.

[0076] In addition, in this embodiment, the outside air passage has a circumferential outside air passage 60 arranged outside the circumferential wall 21 of the motor housing 20, so that outside air circulating through this circumferential outside air passage 60 can efficiently cool the oil in the axial oil passage 55 via the circumferential wall 21.

[0077] Furthermore, in this embodiment, as shown in the partially enlarged view of FIG. 6, in a cross section along a plane perpendicular to the axial direction of the motor 30, the circumferential outside air passage 60 is arranged on an extension line L of a straight line connecting the outer periphery 55a of the axial oil passage 55 and the outer periphery 21a of the circumferential wall 21 of the motor housing 20 at the shortest distance.

[0078] According to the above aspect, since the circumferential outside air passage 60 is laid out as described above, the distance between the axial oil passage 55 and the circumferential outside air passage 60 can be shortened, and the cooling efficiency of the oil in the axial oil passage 55 can be further improved by the flow of outside air through the circumferential outside air passage 60.

[0079] In addition, in this embodiment, the outside air passage has an end outside air passage 61 that is arranged outside the axial end wall 22 of the motor housing 20, so that outside air circulating through this end outside air passage 61 can efficiently cool the oil in the radial oil passage 56 via the axial end wall 22.

[0080] Furthermore, in this embodiment, the rotation of the fan 65 connected to one axial end 33a of the shaft 33 is configured to supply outside air to the outside air passage, so that the rotation of the fan 65 supplies outside air to the outside air passage, and this outside air can effectively cool the motor housing 20 and the oil circulating within the oil passage.

[0081] In addition, in this embodiment, the shroud 75 arranged around the fan 65 guides the outside air inside the shroud 75 into the outside air passage, thereby effectively cooling the motor housing 20 and the oil circulating inside the oil passage.

[0082] Furthermore, in this embodiment, the circumferential outside air passage 60 formed inside the cover member 70 and the end outside air passage 61 formed inside the shroud 75 are configured to be connected to each other, so that the outside air that has flowed through the end outside air passage 61 inside the shroud 75 can reliably flow to the circumferential outside air passage 60 inside the cover member 70, thereby making it possible to cool the inside of the oil passage even more effectively.

[0083] In addition, in this embodiment, fins 26 extending toward the outside air passage are formed on the outer periphery 21a of the circumferential wall 21 of the motor housing 20, so that the heat dissipation area of ​​the motor housing 20 can be increased by the amount of the fins 26, thereby improving both the cooling ability of the motor housing 20 by the outside air flowing through the outside air passage and the cooling ability of the oil in the oil passage formed in the motor housing 20.

[0084] Furthermore, in this embodiment, the oil stored in the oil reservoir 45 on the gear housing 40 side is supplied to the oil receiving portion 46 by the multiple gears 50, 51 that make up the reduction mechanism, and the oil supplied to the oil receiving portion 46 is supplied to the bearing 24 via the axial oil passage 55 and the radial oil passage 56. Therefore, the oil in the oil reservoir 45 can be supplied to the bearing 24 without using an oil pump, thereby simplifying the structure and reducing the number of parts.

[0085] In addition, in this embodiment, the rigidity of the axial end wall 22 of the motor housing 20 and the bearing holder 23 can be improved by the multiple ribs 25 extending from the outer periphery of the bearing holder 23 provided in the motor housing 20, and certain of these ribs 25a also serve as radial oil passages 56, making it possible to simplify and miniaturize the motor housing 20.

[0086] Furthermore, in this embodiment, a notch 23b that connects the radial oil passage 56 and the bearing 24 is formed in part of the circumference of the bearing holder 23 provided in the motor housing 20, and the oil flowing along the specified rib 25a is supplied to the bearing 24 through the notch 23b, so that the oil can be reliably supplied to the bearing by the notch 23b.

[0087] Furthermore, the straddle-type electric vehicle 100 according to the present invention is equipped with the drive unit 10, making it possible to provide a vehicle that saves space and reduces costs. That is, the vehicle drive unit 10 installed in the vehicle 100 according to the present invention can cool oil with a simple configuration without using an oil cooler or the like, and is therefore particularly effective when installed in a straddle-type electric vehicle (two-wheeled vehicle), which requires low cost and has difficulty in securing installation space for a drive unit compared to a four-wheeled vehicle.

[0088] Furthermore, compared to four-wheel vehicles, the vehicle mounted parts of a saddle-type vehicle are more likely to be exposed to the outside air. Therefore, when the drive unit 10 is mounted on the vehicle 100, the motor housing 20 can be exposed directly to the outside air without using a special passage or the like for air guidance, and the oil can be cooled with a small, inexpensive configuration.

[0089] It should be noted that the present invention is not limited to the above-described embodiment, and various modified embodiments are possible within the scope of the gist of the present invention, and such embodiments are also included in the scope of the present invention. [Explanation of symbols]

[0090] 10 vehicle drive unit, 20 motor housing, 21 circumferential wall, 22 axial end wall, 23 bearing holder, 23b notch, 24 bearing, 25, 25a rib, 26 fin, 30 motor, 31 stator, 32 rotor, 33 shaft, 35 gear, 40 gear housing, 45 oil reservoir, 46 oil receiving portion, 55 axial oil passage, 56 radial oil passage, 60 circumferential fresh air passage, 61 end fresh air passage, 65 fan, 70 cover member, 75 shroud.

Claims

1. A motor housing; a motor housed within the motor housing and having a stator, a rotor rotatably disposed inside the stator, and a shaft coupled to a central axis of the rotor; a bearing that rotatably supports one axial end of the shaft and is held by the motor housing; a gear connected to the other axial end of the shaft; a gear housing connected to the motor housing and having an oil reservoir formed at its bottom for storing oil; a reduction mechanism housed in the gear housing, which reduces the rotation speed of the gear and transmits the reduced speed to an output shaft; an oil passage formed in the motor housing so as to guide oil stored in the oil sump to the bearing, A vehicle drive unit, wherein the motor housing is provided with an outside air passage for circulating outside air outside the motor housing.

2. the motor housing has a circumferential wall that covers the radially outer side of the motor in the circumferential direction of the motor, the oil passage includes an axial oil passage formed in the circumferential wall and extending in the axial direction of the motor, 2. The vehicle drive unit according to claim 1, wherein the outside air passage includes a circumferential outside air passage disposed outside the circumferential wall.

3. 3. The vehicle drive unit according to claim 2, wherein, in a cross section taken along a plane perpendicular to the axial direction of the motor, the circumferential outside air passage is disposed on an extension of a straight line connecting an outer periphery of the axial oil passage and an outer periphery of the circumferential wall at the shortest distance.

4. the motor housing has an axial end wall located on one axial end side of the motor, The oil passage includes a radial oil passage formed in the axial end wall and extending in a radial direction of the motor, 3. A drive unit for a vehicle according to claim 2, wherein the fresh air passage comprises an end fresh air passage disposed outside the axial end wall.

5. a fan connected to one axial end of the shaft and rotating in conjunction with the shaft; 5. The vehicle drive unit according to claim 1, wherein the outside air is supplied to the outside air passage by rotation of the fan.

6. A shroud is disposed around the fan to direct the fluid to flow in one direction, 6. A drive unit for a vehicle according to claim 5, wherein the outside air within the shroud is guided into the outside air passage by the rotation of the fan.

7. a fan connected to one end of the shaft in the axial direction and rotating in conjunction with the shaft, wherein the outside air is supplied to the outside air passage by the rotation of the fan, a shroud that directs fluid flow in one direction is disposed around the fan, and the outside air within the shroud is guided to the outside air passage by rotation of the fan, The shroud has a case shape that separates an internal space from an external space, 5. A drive unit for a vehicle according to claim 4, wherein the end outside air passage is formed inside the shroud.

8. the end external air passage is formed inside the shroud, A cover member having a cover shape that separates an internal space from an external space is disposed on an outer periphery of the circumferential wall, 8. The vehicle drive unit according to claim 7, wherein the circumferential outside air passage is formed inside the cover member, and the circumferential outside air passage is configured to communicate with the end outside air passage formed inside the shroud.

9. 5. The vehicle drive unit according to claim 1, wherein the motor housing has an outer periphery formed with fins extending toward the outside air passage.

10. the reduction mechanism has a plurality of gears that can scoop up the oil in the oil reservoir, an oil receiving portion is provided inside the gear housing and above the bearing, 5. The vehicle drive unit according to claim 4, wherein the oil scooped up from the oil reservoir by the plurality of gears is supplied to the oil receiving portion, and the oil supplied to the oil receiving portion is supplied to the bearings via the axial oil passage and the radial oil passage.

11. the motor housing has a bearing holder formed on the axial end wall for holding the bearing, A plurality of ribs extend radially outward from the outer periphery of the bearing holder, One of the ribs extends toward the axial oil passage to form the radial oil passage, 11. The vehicle drive unit according to claim 10, wherein the oil flowing through the axial oil passage is supplied to the bearing along the rib.

12. a notch that communicates the radial oil passage with the bearing is formed in a circumferential portion of the bearing holder, 12. The vehicle drive unit according to claim 11, wherein the oil flowing along the rib is supplied to the bearing through the notch.

13. A straddle-type electric vehicle equipped with the vehicle drive unit according to any one of claims 1 to 4.

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