Drive device

Abstract

The present invention is a drive device in which a motor unit, including a motor housed in a motor housing, and a transmission unit, including a transmission housed in a transmission housing, are integrally connected to a rotary shaft of the motor unit in the axial direction. The motor housing comprises a refrigerant flow path through which a refrigerant flows. The transmission housing comprises: a communication hole that penetrates the transmission housing in the axial direction and communicates with the refrigerant flow path; and a refrigerant storage part that is provided on the outside of a side wall of the transmission housing and temporarily stores the refrigerant flowing in from the communication hole. The transmission comprises a first gear that is lubricated by lubricating oil and is provided to a first shaft connected to the rotary shaft. The refrigerant storage part extends downward from the side of the first gear along the outer periphery of the first gear when viewed from the axial direction, and performs heat exchange between the lubricating oil in the transmission housing and the refrigerant in the refrigerant storage part via a side wall that defines a space between the refrigerant storage part and the transmission.

Description

Drive unit

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

[0002] A drive device is known that is miniaturized by integrating a motor and a transmission (reduction gear). In such a configuration, appropriate measures must be taken to prevent heat from being generated by the motor and the transmission. JP2021-124185A discloses a drive device that is configured to guide lubricating oil from the reduction gear to the motor side and cool the lubricating oil using a refrigerant that cools the motor.

[0003] As mentioned above, in a configuration in which the lubricating oil of the reducer is guided to the motor side, the path through which the lubricating oil flows becomes longer, making it difficult to exchange heat evenly between the lubricating oil and the refrigerant, and there is a problem in that sufficient heat countermeasures cannot be taken.

[0004] The present invention has been made in view of the above problems, and has as its object to provide a drive device that can efficiently take measures against heat in a transmission.

[0005] One aspect of the present invention is a drive device in which a motor unit including a motor housed in a motor housing and a transmission unit including a transmission housed in a transmission housing are axially integrally connected to a rotating shaft of the motor unit. The motor housing has a refrigerant flow path through which a refrigerant flows. The transmission housing has a communication hole that penetrates the transmission housing in the axial direction and communicates with the refrigerant flow path, and a refrigerant reservoir provided on the outside of a side wall of the transmission housing for temporarily storing refrigerant flowing through the communication hole. The transmission is lubricated with lubricating oil and has a first gear provided on a first shaft connected to the rotating shaft. The refrigerant reservoir extends downward from the side of the first gear along the outer periphery of the first gear when viewed in the axial direction, and heat exchange occurs between the lubricating oil in the transmission housing and the refrigerant in the refrigerant reservoir via a side wall that defines a boundary between the refrigerant reservoir and the transmission.

[0006] Fig. 1 is a perspective view of a drive unit of this embodiment. Fig. 2 is a perspective view of the drive unit and an explanatory diagram of a refrigerant reservoir. Fig. 3 is an explanatory diagram of a speed reducer. Fig. 4 is an explanatory diagram of a speed reducer. Fig. 5 is an explanatory diagram of an oil catch tank. Fig. 6 is an explanatory diagram of an oil catch tank.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] Fig. 1 is a perspective view showing the configuration of a drive unit 1 according to an embodiment of the present invention. Fig. 2 is a perspective view of the drive unit 1, illustrating a state in which a lid 61 of a refrigerant reservoir 60 is removed. Fig. 3 is a perspective view of the drive unit 1, illustrating a state in which a reducer housing 21 is removed.

[0009] The drive unit 1 includes a motor unit 10 having a rotating electric machine (motor) 12 and a reducer unit 20 having a reducer 22. These are integrally connected in the axial direction of the rotation shaft of the motor 12. The drive unit 1 is mounted on an electric vehicle and configured as a driving force source that drives the electric vehicle by driving the motor 12. The drive unit 1 is disposed so that its axial direction is perpendicular to the fore-and-aft direction of the vehicle (vehicle width direction).

[0010] The motor 12 is driven by power supplied from a battery and transmits rotation to the drive wheels to drive the electric vehicle. The motor 12 also functions as a generator that generates regenerative power when the electric vehicle decelerates. The reducer 22 includes a speed reduction mechanism and reduces the rotation of the motor 12 before outputting it. The output of the reducer 22 is transmitted to the drive wheels of the vehicle.

[0011] The motor unit 10 is configured by housing a motor 12 in a motor chamber, which is a hollow space formed in a motor housing 11. The reduction gear unit 20 is configured by housing a reduction gear 22 in a reduction gear chamber formed by a lid-shaped reduction gear housing 21 fixed to the motor housing 11. One side surface 15 (see FIG. 3 ) of the motor housing 11 is a wall-like member that separates the motor chamber from the reduction gear chamber. A refrigerant flow path is formed within the motor housing 11, through which a refrigerant flows to cool the motor 12. A portion of the refrigerant flow path opens to a peripheral portion 16 of the motor housing 11 and is configured as a communication hole 19 that communicates with a refrigerant reservoir 60 of the reduction gear housing 21, as described below.

[0012] As shown in Figure 3, the reducer 22 is connected to the rotating shaft of the motor 12 and includes a first shaft 51 having a first gear 41, a second shaft 52 having a second gear 42 meshing with the first gear 41, and a third shaft 53 having a third gear 43 meshing with the second gear 42. The third shaft 53 is connected to the drive wheels and drives the drive wheels. The first gear 41, the second gear 42, and the third gear 43 are arranged side by side in the fore-and-aft direction of the vehicle along the side wall 26. Because the first gear 41 is directly connected to the rotating shaft of the motor 12, it rotates faster than any of these shafts.

[0013] The reducer 22 further includes a parking mechanism 30. The parking mechanism 30 includes an actuator 31, a drive shaft 32, a parking pole 33, and a parking gear 34. The parking gear 34 is fixed coaxially adjacent to the first gear 41 on the first shaft 51. The actuator 31, when operated, engages the parking pole 33 with the parking gear 34 via the drive shaft 32. This mechanically locks the first shaft 51.

[0014] The motor housing 11 and the reducer housing 21 are made of a casting made of a metal with high thermal conductivity (for example, an aluminum alloy).

[0015] Next, a description will be given of measures to deal with heat in the reducer 22 in the drive device 1 configured as above.

[0016] In the drive device 1 , the motor 12 is cooled by the refrigerant that passes through the refrigerant flow path of the motor housing 11 .

[0017] Meanwhile, the reducer 22 is lubricated and cooled by the lubricating oil stored in the reducer housing 21, and it is desirable to provide a configuration for cooling the lubricating oil in order to adequately address the heat generated by the reducer 22. To cool the lubricating oil, it is conceivable to provide an oil cooler or the like outside the reducer 22. However, if an oil cooler is provided, the path through which the lubricating oil flows becomes longer, making it difficult to cool the lubricating oil evenly, resulting in the problem that adequate heat countermeasures cannot be implemented.

[0018] In this embodiment, the following configuration is provided to enable appropriate heat countermeasures to be taken for the reducer 22.

[0019] 4 is an explanatory diagram of the reducer unit 20 as viewed from the motor unit 10 side. FIGS. 5 and 6 are explanatory diagrams of a first catch tank 71 and a second catch tank 72 formed in the reducer housing 21.

[0020] As shown in Figure 4, the reduction gear unit 20 is configured by accommodating a reduction gear 22 in a reduction gear housing 21. The reduction gear housing 21 has a peripheral portion 25 and a side wall 26. The peripheral portion 25 is a flange-shaped portion that surrounds the periphery of the reduction gear housing 21 and abuts against the peripheral portion 16 of the motor housing 11 and is fastened together with bolts or the like. The side wall 26 is a wall-shaped portion that extends in the front-to-rear direction of the vehicle so as to cover the outer side of the reduction gear housing 21 in the vehicle width direction. The reduction gear 22 includes a first shaft 51, a second shaft 52, and a third shaft 53, and each of these shafts is rotatably supported inside the side wall 26 of the reduction gear housing 21 via bearings.

[0021] Upright portions 28a to 28d are provided on the inside of the side wall 26 around the first gear 41, the second gear 42, and the third gear 43, standing from the side wall 26 toward the motor unit 10 so as to surround these gears. Upright portion 28a is formed behind the first gear 41, upright portion 28b is formed above the first gear 41 and behind the second gear 42, upright portion 28c is formed in front of the second gear 42 and above the third gear 43, and upright portion 28d is formed behind the third gear 43.

[0022] These erected portions 28a to 28d have similar shapes on the opposing motor housing 11 and abut against the shapes on the motor housing 11, similar to the peripheral portion 25. Therefore, each gear is surrounded by the side surface 15 of the motor housing 11, the side wall 26 of the reducer housing 21, and the erected portions 28. Having each gear surrounded by these structures and the peripheral portion 25 makes it easier for lubricating oil to reach each gear.

[0023] 1 and 2, a refrigerant reservoir 60 is formed on the outer side of the side wall 26 of the reducer housing 21. The refrigerant reservoir 60 is recessed in an inverted L shape when viewed in the axial direction. A lid 61 that closes the refrigerant reservoir 60 is bolted to the outside.

[0024] As shown in FIG. 4 , when viewed from inside the reducer housing 21, the refrigerant reservoir 60 is located outside the sidewall 26 (indicated by a dotted line in FIG. 4 ). The first gear 41 and the park mechanism 30 are located inside the sidewall 26. The refrigerant reservoir 60 is formed to extend downward from the rear side of the first gear 41 in an L-shape when viewed in the axial direction. A communication hole 29 is provided at the rear end of the peripheral portion 25 of the reducer housing 21, facing the communication hole 19 (see FIG. 3 ) in the peripheral portion 16 of the motor housing 11. Refrigerant from the refrigerant flow path is supplied to the refrigerant reservoir 60 through the communication hole 19 and the communication hole 29. The refrigerant that flows into the refrigerant reservoir 60 flows out of the reducer unit 20 through an outlet 62 (see FIG. 1 ) provided in the lid portion 61. The outflowing refrigerant circulates back to the motor unit 10.

[0025] In this way, the refrigerant reservoir 60 stores the refrigerant for cooling the motor unit 10. Since the refrigerant reservoir 60 and the reducer 22 are adjacent to each other with the side wall 26 in between, heat exchange occurs between the refrigerant in the refrigerant reservoir 60 and the lubricating oil in the reducer housing 21.

[0026] Catch tanks (first catch tank 71, second catch tank 72) that temporarily store lubricating oil are provided on the inner surface of side wall 26 of reducer housing 21. The refrigerant storage section 60 is adjacent to first catch tank 71 and second catch tank 72 via side wall 26, increasing the opportunities for contact between the lubricating oil and refrigerant. Refrigerant storage section 60 can store a sufficient amount of refrigerant therein, and this refrigerant is constantly circulating, allowing the lubricating oil to be appropriately cooled.

[0027] The first catch tank 71 is formed as a frame structure surrounded by a wall made up of an upright portion 28a adjacent to the rear of the first gear 41, a bottom portion 84 extending rearward from the lower portion of the upright portion 28a, and a partition portion 85 extending upward from the rear portion of the bottom portion 84. A first opening 81 is formed in the upper portion of the first catch tank 71, and the first catch tank 71 is configured to be approximately U-shaped.

[0028] Second catch tank 72 is provided adjacent to the rear side of first catch tank 71. Second catch tank 72 is formed as a frame structure surrounded by a wall made up of peripheral portion 25 and partition portion 86, which extends downward from the bottom of partition portion 85 to peripheral portion 25. Second catch tank 72 has second opening 82 at the top, and is configured to be approximately U-shaped.

[0029] The first catch tank 71 and the second catch tank 72 are arranged adjacent to each other in the front-to-rear direction, and the first opening 81 of the first catch tank 71 is arranged above the second opening 82 of the second catch tank 72 .

[0030] These first catch tank 71 and second catch tank 72 are capable of heat exchange via side wall 26 between the lubricating oil temporarily stored therein and the refrigerant stored in refrigerant storage section 60. The lubricating oil scooped up by the rotation of first gear 41 flows into first catch tank 71 and second catch tank 72 as follows.

[0031] A gap is formed between the upright portions 28a and 28b surrounding the first gear 41. This gap is configured as a passage hole 90 that allows the lubricating oil scooped up by the first gear 41 to pass toward the upper left of the first gear. Furthermore, the lubricating oil that is scooped up by the first gear 41 and passes through the passage hole 90 collides with the side wall 26 at the rear upper part of the passage hole 90. An inclined portion 91, which is an inclined wall-like portion, is disposed at this location of the side wall 26. When the lubricating oil that has passed through the passage hole 90 collides with the inclined portion 91, it flows downward along the slope of the inclined portion 91.

[0032] Therefore, the lubricating oil scooped up by the first gear 41 collides with the inclined portion 91 through the passage hole 90 and flows downward from the inclined portion 91. Because the first opening 81 and the second opening 82 are disposed below the inclined portion 91, part of the lubricating oil that flows down flows into the first catch tank 71 through the first opening 81, and the rest flows into the second catch tank 72 through the second opening 82.

[0033] In this way, the lubricating oil scooped up by first gear 41 is temporarily stored in first catch tank 71 and second catch tank 72. Heat exchange occurs between the lubricating oil stored in first catch tank 71 and second catch tank 72 and the refrigerant stored in adjacent refrigerant storage section 60 (shown by dotted lines in FIG. 5 ) via side wall 26, thereby appropriately cooling the lubricating oil. In reducer 22, first gear 41 has the smallest outer diameter compared to second gear 42 and third gear 43. Therefore, even if components such as first catch tank 71 and second catch tank 72 are provided inside side wall 26 around first gear 41 and refrigerant storage section 60 is provided outside side wall 26, the configuration of reducer unit 20 does not increase.

[0034] 6 , the reducer housing 21 includes a protrusion 97 that protrudes from the side wall 26 toward the motor unit 10 below the first gear 41 on the side wall 26 and inclines from rear to front along the first gear 41. Because the park mechanism 30 is provided below the first gear 41, it is difficult to store lubricating oil by providing an upright portion adjacent to the lower part of the first gear 41. Therefore, by providing the protrusion 97, the lubricating oil scooped up by the third gear 43 rotating clockwise runs onto and accumulates on the protrusion 97. The accumulation of lubricating oil on the protrusion 97 ensures that a sufficient amount of lubricating oil is supplied to the first gear 41, allowing the first gear 41 to scoop up a sufficient amount of lubricating oil.

[0035] The bottom 84 of the first catch tank 71 is provided with a first outlet hole 92 formed to allow the lubricating oil to flow downward into the first catch tank 71. The lower part of the second catch tank 72 is also provided with a second outlet hole 94 through which the lubricating oil flows downward into the second catch tank 72. By providing these outlet holes, the lubricating oil stored in each catch tank is constantly circulating, thereby efficiently exchanging heat with the refrigerant in the refrigerant storage section 60. The opening cross-sectional areas of the first outlet hole 92 and second outlet hole 94 are set so that the lubricating oil is appropriately stored and circulated in accordance with the viscosity of the lubricating oil and the operating temperature of the reducer 22.

[0036] The first catch tank 71 is configured to perform gas-liquid separation as follows.

[0037] The bottom 84 of the first catch tank 71 is formed so as to gently descend from the partition 85 toward the front side and to communicate with the first outflow hole 92. Because the bottom 84 of the first catch tank 71 has such a shape, the lubricating oil that flows into the first catch tank 71 from the first opening 81 generates a flow that rotates in a swirling counterclockwise direction.

[0038] The lubricating oil stirred up by each gear splashes and scatters, resulting in the lubricating oil in the reducer housing 21 becoming a gas-liquid mixture containing bubbles. When the lubricating oil is in a gas-liquid mixed state, heat exchange efficiency decreases. Therefore, by rotating the gas-liquid mixed lubricating oil in a spiral in the first catch tank 71, the gas and liquid are more easily separated, and the liquid lubricating oil accumulates. The partition 85 separating the first catch tank 71 and the second catch tank 72 is formed with a downflow hole 93 that allows the lubricating oil stored in the first catch tank 71 to flow down to the second catch tank 72. Therefore, the lubricating oil that has become liquid in the first catch tank 71 flows down from the downflow hole 93 to the second catch tank 72.

[0039] Furthermore, the second opening 82 of the second catch tank 72 is disposed lower than the first opening 81 of the first catch tank 71. Therefore, when the amount of lubricating oil flowing into the second catch tank 72 increases, the lubricating oil with a high foam content has a low specific gravity and therefore collects near the upper second opening 82, from where it flows into the first catch tank 71. As described above, gas-liquid separation of the lubricating oil is performed in the first catch tank 71, so the liquid lubricating oil flows down from the downflow hole 93 into the second catch tank 72. As a result, the liquid lubricating oil is likely to accumulate in the second catch tank 72.

[0040] The second catch tank 72 is configured to be larger in the vertical direction than the first catch tank 71 and has a larger volume, so that the liquid lubricating oil can more effectively exchange heat through the side wall 26 .

[0041] Liquid lubricating oil flows out from the second outlet hole 94 on the lower side of the second catch tank 72, and is scooped up by the third gear 43, which is the lowest part in the reducer 22, and supplied to each shaft and gear, which are properly lubricated and cooled.

[0042] As described above, in this embodiment, the drive device 1 is configured by integrally connecting the motor unit 10 including the motor 12 housed in the motor housing 11 and the speed reducer unit 20 (transmission unit) including the speed reducer 22 (transmission) housed in the speed reducer housing 21 (transmission housing) in the axial direction to the rotating shaft of the motor unit 10. The motor housing 11 has a refrigerant flow path through which a refrigerant flows. The speed reducer housing 21 has a communication hole 29 that axially penetrates the inside of the speed reducer housing 21 and communicates with the refrigerant flow path, and a refrigerant reservoir 60 that is provided on the outside of the side wall 26 of the speed reducer housing 21 and temporarily stores the refrigerant that flows in from the communication hole 29. The speed reducer 22 is lubricated with lubricating oil and has a first gear 41 provided on a first shaft 51 that is connected to the rotating shaft. When viewed from the axial direction, the refrigerant storage section 60 extends downward from the side of the first gear 41 along the outer periphery of the first gear 41, and heat exchange occurs between the lubricating oil in the reducer housing 21 and the refrigerant in the refrigerant storage section 60 via the side wall 26 that defines the space between the refrigerant storage section 60 and the reducer 22.

[0043] In this configuration, the lubricating oil in the reduction gear unit 20 can be cooled by the refrigerant introduced into the refrigerant reservoir 60 provided on the outside of the reduction gear housing 21. Furthermore, since a sufficient volume of refrigerant always circulates in the refrigerant reservoir 60, appropriate heat countermeasures for the reduction gear unit 20 can be implemented.

[0044] In this embodiment, the drive unit 1 is mounted on a vehicle, the reducer housing 21 is connected to the axial side surface 15 of the motor unit 10, and the side wall 26 extends in the front-rear direction of the vehicle.

[0045] In this configuration, the reduction gear unit 20 is integrally connected to the side surface 15 of the motor unit 10 , so that the refrigerant of the motor 12 can be easily guided to the reduction gear 22 .

[0046] In addition, in this embodiment, a first catch tank 71 having a first opening 81 at the top is provided on the inside of the side wall 26 in the refrigerant storage section 60 via the side wall 26, and the lubricating oil scooped up by the first gear 41 flows into the first catch tank 71 from the first opening 81 and is stored in the first catch tank 71.

[0047] In this configuration, by storing the lubricating oil in the first catch tank 71, heat exchange can be performed between the refrigerant in the refrigerant storage section 60 and the lubricating oil in the first catch tank 71 via the side wall 26.

[0048] In this embodiment, the first catch tank 71 is provided at its bottom 84 with a first outflow hole 92 that allows the stored lubricating oil to flow downward.

[0049] In this configuration, the lubricating oil in the first catch tank 71 is allowed to flow out from the first outflow hole 92, which promotes lubrication of the lubricating oil in the first catch tank 71 and allows for more appropriate heat exchange.

[0050] In this embodiment, the first gear 41 is surrounded by an upright portion 28 that stands upright in the axial direction from the side wall 26, and a passage hole 90 is formed in a part of the upright portion 28 to allow passage of the lubricating oil scooped up by the first gear 41. The side wall 26 is provided with an inclined portion 91 that is a wall-like portion against which the lubricating oil that has passed through the passage hole 90 collides and that guides the collided lubricating oil to the first catch tank 71 located below.

[0051] In this configuration, the lubricating oil is scooped up by the first gear 41, which is directly connected to the rotating shaft of the motor 12 and has the highest rotational speed, and the scooped up lubricating oil is led to the first catch tank 71.Therefore, the lubricating oil can be efficiently led to the first catch tank 71 within the reducer unit 20 without any special configuration.

[0052] In addition, in this embodiment, a second catch tank 72 having a second opening 82 is provided in the refrigerant storage section 60 via the side wall 26 at a position adjacent to the rear side of the first catch tank 71 in the vehicle's fore-and-aft direction, and the second catch tank 72 has a second outflow hole 94 in its lower part for allowing the stored lubricating oil to flow downward.

[0053] In this configuration, in addition to the first catch tank 71, a second catch tank 72 is provided adjacent to the refrigerant storage section 60 via the side wall 26, which increases the opportunities for heat exchange with the refrigerant, allowing for more appropriate heat exchange.

[0054] In this embodiment, the reducer 22 includes a second shaft 52 having a second gear 42 that meshes with the first gear 41, and a third shaft 53 having a third gear 43 that meshes with the second gear 42. The first gear 41, the second gear 42, and the third gear 43 are arranged side by side along the side wall 26 in the front-to-rear direction of the vehicle, and the side wall 26 of the reducer housing 21 includes a protrusion 97 that protrudes in the axial direction from the side wall 26 below the first gear 41 and is inclined from the first gear 41 toward the third gear 43.

[0055] In this configuration, the lubricating oil scooped up by the third gear 43 can be easily collected in the protrusion 97 at the bottom of the first gear 41, so that the first gear 41 can efficiently scoop up the lubricating oil.

[0056] Furthermore, in this embodiment, the first gear 41 has the smallest outer diameter compared to the second gear 42 and the third gear 43, so even if a first catch tank 71, a second catch tank 72, etc. are provided inside the side wall 26 around the first gear 41 and a refrigerant storage section 60 is provided outside the side wall 26, the configuration of the reduction gear unit 20 does not increase.

[0057] In this embodiment, second catch tank 72 is formed vertically elongated so as to extend in the up-down direction, first catch tank 71 is disposed adjacent to second catch tank 72 in the front-to-rear direction, and first opening 81 is disposed above second opening 82. A bottom 84 of first catch tank 71 is provided with a downflow hole 93 through which lubricating oil flows down to second catch tank 72. Bottom 84 of first catch tank 71 gently descends from downflow hole 93 toward the front side and communicates with first outflow hole 92.

[0058] In this configuration, the lubricating oil that has flowed into first catch tank 71 rotates in a swirling manner at bottom 84, causing gas-liquid separation, and the liquid lubricating oil can flow down through downflow hole 93 into second catch tank 72. This allows the liquid lubricating oil to effectively exchange heat with the refrigerant.

[0059] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0060] In the present embodiment, the reduction gear unit 20 is described as including the reduction gear 22 that reduces the rotation of the motor 12, but this is not limiting. The drive device 1 may be configured to include a transmission unit including a transmission that can reduce or increase the rotation of the motor 12 in a stepped or continuously variable manner.

[0061] In addition, although the first catch tank 71 is configured to have a first outflow hole 92 at the bottom 84, depending on the characteristics of the lubricating oil, the first outflow hole 92 may not be provided and the lubricating oil may flow down into the second catch tank 72 only through the downflow hole 93.

Claims

1. A drive device in which a motor unit having a motor housed in a motor housing and a transmission unit having a transmission housed in a transmission housing are integrally connected in the axial direction to a rotating shaft of the motor unit, wherein the motor housing has a refrigerant flow path through which a refrigerant flows, and the transmission housing has: a communication hole that passes axially through the transmission housing and communicates with the refrigerant flow path, and a refrigerant reservoir provided on the outside of a side wall of the transmission housing and temporarily stores the refrigerant that flows in from the communication hole, the transmission is lubricated with lubricating oil and has a first gear provided on a first shaft connected to the rotating shaft, and the refrigerant reservoir extends downward from the side of the first gear along the outer periphery of the first gear when viewed in the axial direction, and heat exchange occurs between the lubricating oil in the transmission housing and the refrigerant in the refrigerant reservoir via the side wall that defines the space between the refrigerant reservoir and the transmission.

2. A drive unit according to claim 1, wherein the drive unit is mounted on a vehicle, the transmission housing is connected to a side surface of the motor housing in the axial direction, and the side wall extends in the longitudinal direction of the vehicle.

3. A drive device as claimed in claim 2, wherein a first catch tank having a first opening at its top is provided inside the side wall, between the refrigerant storage section and the side wall, and the lubricating oil scooped up by the first gear flows into the first catch tank through the first opening and is temporarily stored in the first catch tank.

4. A drive device according to claim 3, wherein the first catch tank has a first outlet hole at its bottom for allowing the stored lubricating oil to flow downward.

5. A drive device as claimed in claim 4, wherein the first gear is surrounded by an upright portion that stands upright in the axial direction from the side wall, a passage hole is formed in a part of the upright portion to allow the lubricating oil scooped up by the first gear to pass through, and the side wall is provided with a wall-like portion against which the lubricating oil that has passed through the passage hole collides, and an inclined portion that guides the colliding lubricating oil to the first catch tank located below.

6. A drive device as claimed in claim 4, wherein a second catch tank having a second opening is provided in the refrigerant storage section via the side wall at a position adjacent to the rear side of the first catch tank in the longitudinal direction of the vehicle, and the second catch tank is provided at its lower part with a second outflow hole for allowing the stored lubricating oil to flow downward.

7. A drive device as claimed in claim 6, wherein the transmission is a reducer and comprises a second shaft having a second gear that meshes with the first gear, and a third shaft having a third gear that meshes with the second gear, the first gear, the second gear and the third gear are arranged side by side along the side wall in the longitudinal direction of the vehicle, and the transmission housing comprises a protrusion that protrudes axially from the inner wall of the transmission housing below the first gear and inclined from the first gear towards the third gear.

8. A drive device according to claim 7, wherein the first gear has the smallest outer diameter compared to the second gear and the third gear.

9. A drive device as claimed in claim 6, wherein the second catch tank is formed vertically so as to extend in the up-down direction, the first catch tank is arranged adjacent to the second catch tank in the front-to-rear direction, the first opening is arranged above the second opening, a side of the first catch tank is provided with a downflow hole through which the lubricating oil flows down into the second catch tank, and the bottom of the first catch tank flows gently downward from the downflow hole towards the front and communicates with the first outflow hole.

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