Drive device

Abstract

[Problem] To provide a drive device that enables reducing the height dimension. [Solution] A drive device drives a drive wheel and is equipped with: a motor as a drive source; a power transmission mechanism for transmitting power from the motor to the drive wheel; and a casing which has a motor housing part for housing the motor, and a mechanism housing part for housing the power transmission mechanism. The power transmission mechanism has: an input shaft to which the power is inputted from the motor; an intermediate shaft which is disposed above the input shaft and to which the power is transmitted from the input shaft; and an output shaft which is disposed below the intermediate shaft and transmits, to the drive wheel, the power which has been transmitted from the intermediate shaft. The mechanism housing part is provided with: a breather chamber that is disposed in a region positioned above the output shaft and has a passage connecting to the outside; and a front chamber that is disposed between the breather chamber and the output shaft, connects to the breather chamber via the connecting passage, and has a side wall interposed between the connecting passage and the output shaft.

Description

Drive unit

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

[0002] Patent Document 1 discloses a torque transmission device as a driving device, which transmits rotation of an input shaft to an output shaft via an intermediate shaft.

[0003] The rotational center line of the input shaft is located vertically lower than the rotational center line of the output shaft. The rotational center line of the intermediate shaft is located vertically lower than the rotational center line of the input shaft. A breather chamber is provided vertically above the intermediate shaft.

[0004] Japanese Patent Application Laid-Open No. 2007-278372

[0005] However, in some cases, the intermediate shaft is located above the input shaft and the output shaft depending on the layout of the gears that make up the drive unit. In this case, the breather chamber located above the intermediate shaft is located higher, which increases the height of the drive unit.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a drive device that can reduce the height dimension.

[0007] According to one aspect of the present invention, there is provided a drive device for driving drive wheels, the drive device comprising: a motor as a drive source; a power transmission mechanism that transmits power from the motor to the drive wheels; and a casing having a motor housing portion that houses the motor and a mechanism housing portion that houses the power transmission mechanism, wherein the power transmission mechanism has an input shaft to which power is input from the motor, an intermediate shaft that is arranged so as to be positioned higher than the input shaft when mounted on the vehicle and to which power is transmitted from the input shaft, and an output shaft that is arranged so as to be positioned lower than the intermediate shaft when mounted on the vehicle and to transmit the power transmitted from the intermediate shaft to the drive wheels, and the mechanism housing portion is provided with: a breather chamber that is arranged in an area located above the output shaft when mounted on the vehicle and has a passage that communicates with the outside; and a vanguard chamber that is arranged between the breather chamber and the output shaft, communicates with the breather chamber via a communication passage, and has a side wall that is interposed between the communication passage and the output shaft.

[0008] According to one aspect of the present invention, the output shaft is disposed so as to be located below the intermediate shaft, and a breather chamber is provided above the output shaft.

[0009] Therefore, compared to a case where a breather chamber must be provided above the intermediate shaft, the height dimension of the drive unit can be reduced.

[0010] FIG. 1 is a plan view of the drive unit according to this embodiment. FIG. 2 is a view showing an end face of the housing. FIG. 3 is a view showing the inner surface of the case. FIG. 4 is a perspective view showing the vanguard chamber with the plate removed, viewed from diagonally below. FIG. 5 is an enlarged view showing the vanguard chamber with the plate attached, viewed from diagonally below. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6.

[0011] A driving device 10 according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0012] FIG. 1 is a plan view of the drive unit 10 according to this embodiment. FIG. 2 is a view showing the end face of the housing 20, showing cross sections of the end of the input shaft 52, the end of the intermediate shaft 56, and the end of the output shaft 58. FIG. 3 is a view showing the inner surface of the case 24. FIG. 4 is a perspective view showing the front chamber 300 with the plate 350 removed, as viewed obliquely from below. FIG. 5 is an enlarged view showing the front chamber 300 with the plate 350 attached. FIG. 6 is a perspective view showing the front chamber 300 with the plate 350 attached, as viewed obliquely from below. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6.

[0013] In addition, the upward direction U, downward direction D, forward direction FR, rearward direction RR, leftward direction L, and rightward direction R shown in the figure indicate directions when the device is installed in a vehicle.

[0014] 1, a drive unit 10 is used in, for example, an electric vehicle. The drive unit 10 drives drive wheels. The drive source for driving the drive wheels is a motor.

[0015] The casing 12 of the drive unit 10 has a housing 20, a cover 22 attached to one side of the housing 20, and a case 24 attached to the other side of the housing 20. When the drive unit 10 is mounted on a vehicle, the case 24 faces the left side L of the vehicle and the cover 22 faces the right side R of the vehicle.

[0016] (Housing) A motor accommodating portion (not shown) is formed inside the housing 20. A motor (not shown) is accommodated in the motor accommodating portion.

[0017] 2, a housing recess 32 is formed at the end of the housing 20 on the case 24 side. The housing recess 32, together with the case 24, constitutes a mechanism accommodating portion 30 that accommodates the power transmission mechanism 50.

[0018] The bottom surface of the housing recess 32 constitutes a housing recess wall surface 32B as a mechanism wall surface. As a mechanism wall surface, the housing recess wall surface 32B faces the power transmission mechanism 50 in the mechanism accommodating portion 30. An end surface of the housing recess peripheral wall 34 surrounding the housing recess wall surface 32B constitutes a mating surface that is butted against the case 24.

[0019] 3, a case recess 42 that constitutes the mechanism accommodating portion 30 together with the housing recess 32 is formed on the inner surface of the case 24 that constitutes the housing 20 side. An end face of a case recess peripheral wall 44 that surrounds a case recess wall surface 42B of the case recess 42 constitutes a mating surface that abuts against an end face of the housing recess peripheral wall 34 of the housing 20. When the case recess peripheral wall 44 abuts against the housing recess peripheral wall 34 of the housing 20, the housing recess 32 and the case recess 42 form the mechanism accommodating portion 30 between the housing 20 and the case 24.

[0020] (Power Transmission Mechanism) As shown in FIG. 2, the power transmission mechanism 50 transmits the power of the motor described above to drive wheels (not shown) provided on the vehicle.

[0021] The power transmission mechanism 50 has an input shaft 52 to which power is input from the motor, and an intermediate shaft 56 that is positioned above the input shaft 52 and to which power is transmitted from the input shaft 52. The power transmission mechanism 50 also has an output shaft 58 that is positioned below the intermediate shaft 56 in the installed state and that transmits the power transmitted from the intermediate shaft 56 to the drive wheels described above.

[0022] (Input Shaft) More specifically, the input shaft 52 extends from the housing recess wall surface 32B of the housing recess 32. The input shaft 52 is rotatably supported by the housing recess wall surface 32B. The input shaft 52 is disposed in a position closer to the front (FR) of the vehicle in the drive unit 10. The input shaft 52 extends in the left-right direction of the drive unit 10.

[0023] (Intermediate Shaft) The intermediate shaft 56 described above is disposed in a position in the drive unit 10 on the vehicle rearward (RR) side of the input shaft 52 and on the upper U side of the input shaft 52. The intermediate shaft 56 extends in the left-right direction so as to be parallel to the input shaft 52. The intermediate shaft 56 is rotatably supported on the housing recess wall surface 32B.

[0024] (Output Shaft) The output shaft 58 described above is disposed in a position further toward the rear (RR) of the vehicle than the intermediate shaft 56 in the drive unit 10 and on the D side below the intermediate shaft 56. The output shaft 58 is disposed below the input shaft 52. The output shaft 58 extends in the left-right direction so as to be parallel to the intermediate shaft 56. The output shaft 58 is rotatably supported on the housing recess wall surface 32B.

[0025] As shown in FIG. 1 , one end of the output shaft 58 extends beyond the casing 12 toward the left L of the vehicle. A drive wheel (not shown) is provided at one end of the output shaft 58. The other end of the output shaft 58 extends beyond the casing 12 toward the right R of the vehicle. A drive wheel (not shown) is fixed to the other end of the output shaft 58.

[0026] (First Gear and Second Gear) The input shaft 52 is provided with a first gear 60 and a second gear (not shown) that rotate together with the input shaft 52. The first gear 60 and the second gear are arranged side by side in the axial direction of the input shaft 52. The second gear forms a parking gear with a larger diameter than the first gear 60.

[0027] 2, the intermediate shaft 56 is provided with a third gear 70 and a fourth gear (not shown) that rotate together with the intermediate shaft 56. The third gear 70 and the fourth gear are arranged side by side in the axial direction of the intermediate shaft 56.

[0028] The third gear 70 meshes with the first gear 60 provided on the input shaft 52. The third gear 70 has a larger diameter than the first gear 60, and transmits the rotation of the input shaft 52 to the intermediate shaft 56 at a reduced speed. The fourth gear has a smaller diameter than the third gear 70. The fourth gear transmits the rotation of the intermediate shaft 56 to the output shaft 58.

[0029] (Fifth Gear) The output shaft 58 is provided with a fifth gear 76 that rotates together with the output shaft 58. The fifth gear 76 meshes with the fourth gear (not shown). The fifth gear 76 has a larger diameter than the fourth gear, and transmits the rotation of the intermediate shaft 56 to the output shaft 58 after reducing the rotation speed.

[0030] A differential gear mechanism (not shown) that constitutes a differential gear together with the fifth gear 76 is disposed closer to the housing recess wall surface 32B than the fifth gear 76.

[0031] (Mechanism Housing Section) The mechanism housing section 30 of the casing 12 is provided with a gear arrangement area 80 in which the gears 60, 70, 76 are arranged. The mechanism housing section 30 is also provided with a breather chamber 82 that is located in an area U above the output shaft 58 and has a passage (148) that communicates with the outside. The breather chamber 82 allows gas to flow between the mechanism housing section 30 and the outside of the casing 12, and constitutes a chamber for adjusting the pressure inside the mechanism housing section 30.

[0032] Additionally, a front chamber 300 is provided in the mechanism housing portion 30 between the breather chamber 82 and the output shaft 58. The front chamber 300 communicates with the breather chamber 82 via a communication passage 302 (see FIG. 4). The front chamber 300 has a side wall 354 (see FIGS. 6 and 7) interposed between the communication passage 302 and the output shaft 58.

[0033] (Guide portion) A guide portion 306 is provided on the outer periphery of the fifth gear 76 of the output shaft 58, and guides the oil scooped up by the fifth gear 76 toward a second rib 344 (described later) that serves as one of the ribs of the front chamber 300. The guide portion 306 and the front chamber 300 are spaced apart, and an upper communication passage 307 that communicates the lower space of the guide portion 306 upward is formed between the tip of the guide portion 306 and the front chamber 300.

[0034] The guide portion 306 is formed by butting together an arc-shaped housing arc rib 306A (see Figure 2) formed on the housing recess wall surface 32B of the housing 20 and an arc-shaped case arc rib 306B (see Figure 3) formed on the case recess wall surface 42B of the case 24.

[0035] (Blocking Rib) A blocking rib 308 is provided at the lower part of the tip of the guide portion 306 located in the front chamber 300 to block the flow of oil scooped up by the differential gear mechanism toward the front chamber 300. The blocking rib 308 is formed only on the housing recess wall surface 32B of the housing 20.

[0036] The blocking rib 308 has an extension portion 308A that extends from the middle of the housing arc rib 306A toward the front of the vehicle FR and contacts the lower part of the front guard chamber 300, and an inclined portion 308B that extends downward D from the end of the extension portion 308A toward the front of the vehicle FR.

[0037] (Oil Reservoir) An oil reservoir 310 is provided in the housing recess wall surface 32B at a position D below the tip of the guide portion 306 located on the side of the second rib 344, which serves as one of the ribs of the front chamber 300. The oil reservoir 310 is formed by a depression formed in the housing recess wall surface 32B, which serves as the mechanism wall surface.

[0038] (Communication Path) A communication path 314 (see FIGS. 5 and 7) is formed between the front chamber 300 and the breather chamber 82, allowing the oil guided by the guide portion 306 to flow toward the intermediate shaft 56. The communication path 314 is configured as a groove provided in a thick portion 380 (see FIG. 7) formed in the housing recess wall surface 32B, which serves as a mechanism wall surface, between the front chamber 300 and the breather chamber 82.

[0039] (Breather Chamber) As shown in FIG. 2, the housing 20 side of the breather chamber 82 is defined by the housing recess wall surface 32B and a housing surrounding rib 100 formed on the housing recess wall surface 32B.

[0040] As shown in FIG. 3, the case 24 side of the breather chamber 82 is defined by the case recess wall surface 42B and a case surrounding rib 102 formed on the case recess wall surface 42B.

[0041] (Breather chamber: case side) As shown in Figure 3, the case surrounding rib 102 has a part of the case recess peripheral wall 44 that surrounds the case recess 42, and a case extension rib 320 that extends from the case recess peripheral wall 44 toward the front FR of the vehicle above U where the output shaft 58 is located.

[0042] The case surrounding rib 102 has a case inclined rib 322 that inclines upward U from the end of the case extending rib 320 on the vehicle front FR side toward the vehicle front FR. The case surrounding rib 102 also has a case front rib 324 that connects the end of the case inclined rib 322 to the case recess peripheral wall 44 on the vehicle front FR side.

[0043] A case partitioning rib 326 is formed between the case recess peripheral wall 44 and the case extension rib 320. As a result, the breather chamber 82 is partitioned by the case partitioning rib 326 into a small chamber 120 on the vehicle rear (RR) side and a large chamber 122 on the vehicle front (FR) side.

[0044] (Breather Chamber: Housing Side) As shown in FIGS. 3 to 6 , the housing surrounding rib 100 has a part of the housing recess peripheral wall 34 that abuts against a part of the case recess peripheral wall 44 that forms the case surrounding rib 102 .

[0045] The housing surrounding rib 100 has a housing extension rib 330 that abuts against the case extension rib 320 of the case surrounding rib 102, and a housing inclined rib 332 that abuts against the case inclined rib 322. The housing surrounding rib 100 has a housing front rib 334 that abuts against the case front rib 324 of the case surrounding rib 102.

[0046] A housing partitioning rib 336 is formed between the housing recess peripheral wall 34 and the housing extension rib 330. As a result, the breather chamber 82 is partitioned by the housing partitioning rib 336 into a small chamber 120 on the vehicle rear (RR) side and a large chamber 122 on the vehicle front (FR) side.

[0047] The housing partitioning rib 336 and the case partitioning rib 326 (see FIG. 3) are positioned at positions offset in the fore-and-aft direction of the vehicle, thereby forming a gap (not shown) between the housing partitioning rib 336 and the case partitioning rib 326 that connects the small chamber 120 on the housing 20 side and the large chamber 122 on the case 24 side.

[0048] A vent hole (not shown) connected to, for example, a vent pipe 148 (see FIG. 2) protruding from the housing 20 is opened in the large chamber 122 of the breather chamber 82. As a result, a passage communicating with the outside of the casing 12 is formed in the breather chamber 82 by the vent hole (not shown) and the vent pipe 148.

[0049] 2, the front chamber 300 is disposed above a differential gear mechanism (not shown) that constitutes a differential gear together with the fifth gear 76 provided on the output shaft 58. The front chamber 300 is configured to include a rib formed on the housing recess wall surface 32B of the housing 20.

[0050] The wall surface of the front chamber 300 is formed on the housing recess wall surface 32B (see FIG. 4) as the mechanism wall surface of the mechanism accommodating section 30, and is configured to include a top rib 340 extending along the breather chamber 82. The above-mentioned communication passage 302 that connects the front chamber 300 to the breather chamber 82 opens into the top rib 340. Threaded holes 340B are also formed at both ends of the top rib 340.

[0051] The wall surface of the vanguard chamber 300 is formed on the housing recess wall surface 32B and includes a first rib 342 extending downward D from one end of the top surface rib 340 on the vehicle front FR side. The wall surface of the vanguard chamber 300 is formed on the housing recess wall surface 32B and includes a second rib 344 extending downward D from the other end of the top surface rib 340 on the vehicle rear RR side.

[0052] 5 and 6, the wall surface of the vanguard chamber 300 includes a plate 350 bent to have an L-shaped cross section. The plate 350 has a vertical wall 352 disposed on the end face side of the top surface rib 340, the first rib 342, and the second rib 344, and the aforementioned horizontal wall 354 extending from the lower edge of the vertical wall 352 toward the housing recess wall surface 32B, which serves as the mechanism wall surface.

[0053] The plate 350 has a side edge portion of the vertical wall 352 on the vehicle front side (FR) that comes into surface contact with the end surface of the first rib 342. The plate 350 has a side edge portion of the vertical wall 352 on the vehicle rear side (RR) that comes into surface contact with the end surface of the second rib 344.

[0054] The plate 350 is fixed to the top surface rib 340 by inserting a screw 360 into a through-hole (not shown) in the vertical wall 352 and threading it into a screw hole 340 B in the top surface rib 340 .

[0055] (Gap) The width dimension of the lateral wall 354 in the vehicle front-rear direction is narrower than that of the vertical wall 352. The width dimension of the lateral wall 354 is smaller than the distance from the first rib 342 to the second rib 344. As a result, a rear gap 370 (see FIG. 6 ) is formed between the lateral wall 354 and the second rib 344.

[0056] The length of the lateral wall 354 toward the housing recess wall surface 32B is smaller than the protruding length of the first rib 342 and the second rib 344 protruding from the housing recess wall surface 32B. As a result, a gap 372 (see FIGS. 6 and 7) is formed between the end of the lateral wall 354 of the plate 350 and the housing recess wall surface 32B serving as the mechanism wall surface.

[0057] Here, the side wall 354 may be formed of a rib protruding from the housing recess wall surface 32B. However, in this embodiment, the side wall 354 of the front chamber 300 is formed of the side wall 354 of the plate 350 having an L-shaped cross section, which makes it possible to form the gap 372 described above that connects the front chamber 300 and the mechanism housing portion 30.

[0058] The second rib 344, which is one of the first rib 342 and the second rib 344, is set to a length that reaches a position D below the lateral wall 354 of the plate 350 (see FIG. 5). The first rib 342, which is the other rib, is set to a length that does not reach the lateral wall 354 (see FIG. 5).

[0059] As a result, the opening of the front chamber 300 toward the rear of the vehicle RR is blocked by the second rib 344. Meanwhile, the front chamber 300 has a front gap 374 (see FIG. 5 ) that opens toward the front of the vehicle FR between the end of the first rib 342 and the side wall 354.

[0060] 4 and 7, the aforementioned communication passage 302, which connects the front chamber 300 and the breather chamber 82, is configured as a tunnel formed in a thick portion 380 (see FIG. 7) of the housing recess wall surface 32B, which serves as a mechanical wall surface. The end of the communication passage 302, which opens into the top rib 340 of the front chamber 300, opens at a position closer to the vertical wall 352 of the plate 350 than to the housing recess wall surface 32B, which serves as a mechanical wall surface (see FIG. 7). The communication passage 302 slopes toward the right (R) of the vehicle as it extends from the top rib 340 toward the breather chamber 82 (see FIG. 7).

[0061] 2, 4, and 7, a rectangular recess 382 is formed in the housing recess wall surface 32B, which serves as a mechanical wall surface in the front chamber 300. In addition, as shown in Fig. 1, a bulge 384 that protrudes outward is formed on the back side of the housing recess wall surface 32B on which the recess 382 is formed.

[0062] (Explanation of Air Flow) When the pressure inside the mechanism housing section 30 increases, the air in the mechanism housing section 30 enters the front chamber 300 through the rear gap 370, the gap 372, or the front gap 374 formed in the front chamber 300 (see FIG. 6). The air in the front chamber 300 enters the small chamber 120 of the breather chamber 82 through the communication passage 302 (see FIGS. 4 and 7). The air in the small chamber 120 enters the large chamber 122 through a gap (not shown) formed between the housing partition rib 336 and the case partition rib 326. The air in the large chamber 122 is discharged to the outside of the casing 12 through a vent hole (not shown) opening into the large chamber 122 and the vent pipe 148 (see FIG. 2).

[0063] When the pressure inside the mechanism housing portion 30 decreases, the air outside the casing 12 flows in the opposite direction to that described above, and is drawn into the mechanism housing portion 30 .

[0064] 2, during forward travel, the fifth gear 76 of the output shaft 58 rotates counterclockwise (CCW). As a result, the oil scooped up by the fifth gear 76 is guided along the guide portion 306 toward the second rib 344 of the front chamber 300.

[0065] The second rib 344 of the front chamber 300 has a length that reaches downward on the D side below the lateral wall 354 of the plate 350 of the front chamber 300 (see FIG. 5 ). As a result, the opening of the front chamber 300 toward the vehicle rear RR is blocked by the second rib 344. Therefore, the second rib 344 prevents the oil guided by the guide portion 306 from entering the front chamber 300 from the vehicle rear RR.

[0066] A portion of the oil guided toward the second rib 344 enters the oil reservoir 310 (see FIG. 5). A portion of the oil that enters the oil reservoir 310 flows downward D and is supplied to the differential gear mechanism.

[0067] Another portion of the oil that has entered the oil reservoir 310 is supplied to the third gear 70 and the fourth gear (not shown) provided on the intermediate shaft 56 via the upper communication passage 307 and the communication passage 314 (see FIG. 5). Also, a portion of the oil guided toward the second rib 344 by the guide portion 306 flows along the vertical wall 352 of the plate 350 of the front chamber 300, and is supplied to the third gear 70 and the fourth gear (not shown) provided on the intermediate shaft 56 (see FIG. 5).

[0068] Some of the oil scooped up by the fifth gear 76 of the output shaft 58 may enter the front chamber 300 through the rear gap 370, the gap 372, or the front gap 374 of the front chamber 300 (see FIG. 6). The oil that has entered the front chamber 300 is discharged from the rear gap 370, the gap 372, or the front gap 374 to the mechanism housing portion 30 (see FIG. 6).

[0069] The first rib 342 of the front chamber 300 is set to a length that does not reach the side wall 354 (see FIG. 5). As a result, a front gap 374 that opens toward the vehicle front FR is formed in the front chamber 300 between the end of the first rib 342 and the side wall 354 (see FIG. 5). Therefore, oil that has entered the front chamber 300 is promoted to be discharged from the front gap 374 to the mechanism housing portion 30 by oil flowing from the vehicle rear RR toward the vehicle front FR.

[0070] (Functions and Effects) The main functions and effects of the drive device 10 configured as above will be summarized below.

[0071] (1) The drive unit 10 is a device that drives drive wheels. The drive unit 10 includes a motor as a drive source, a power transmission mechanism 50 that transmits power from the motor to the drive wheels, and a casing 12 that includes a motor housing (inside the housing 20) that accommodates the motor and a mechanism housing 30 that accommodates the power transmission mechanism 50. The power transmission mechanism 50 includes an input shaft 52 to which power is input from the motor, and an intermediate shaft 56 that is positioned above the input shaft 52 in a vehicle-mounted state and transmits power from the input shaft 52. The power transmission mechanism 50 includes an output shaft 58 that is positioned below the intermediate shaft 56 in a vehicle-mounted state and transmits power transmitted from the intermediate shaft 56 to the drive wheels. The mechanism housing 30 includes a breather chamber 82 that is positioned above the output shaft 58 in a vehicle-mounted state and has a passage 148 that communicates with the outside. The breather chamber 82 is located in a region above the output shaft 58 in a vehicle-mounted state. The mechanism housing section 30 is provided with a vanguard chamber 300 which is disposed between the breather chamber 82 and the output shaft 58, is connected to the breather chamber 82 via a communication passage 302, and has a lateral wall 354 interposed between the communication passage 302 and the output shaft 58.

[0072] According to this embodiment, the output shaft 58 is disposed so as to be located at a position D below the intermediate shaft 56 , and a breather chamber 82 is provided above the output shaft 58 at a position U above the output shaft 58 .

[0073] Therefore, compared to a case where the breather chamber 82 must be provided above the intermediate shaft 56, the height dimension of the drive unit 10 can be reduced.

[0074] Furthermore, in the drive unit 10 of this embodiment, a front chamber 300 is provided between the breather chamber 82 and the output shaft 58, and the breather chamber 82 is in communication with the front chamber 300 via a communication passage 302. In this way, the front chamber 300 and the communication passage 302 are present between the breather chamber 82 and the mechanism housing 30, so that oil is prevented from entering the breather chamber 82 compared to when an opening provided in the breather chamber 82 opens to the mechanism housing 30.

[0075] (2) The wall surface of the front chamber 300 is formed on the housing recess wall surface 32B, which serves as a mechanism wall surface facing the power transmission mechanism 50 in the mechanism accommodating portion 30, and includes a top rib 340 extending along the breather chamber 82. The wall surface of the front chamber 300 is formed on the housing recess wall surface 32B and includes a first rib 342 extending downward D from one end of the top rib 340. The wall surface of the front chamber 300 is formed on the housing recess wall surface 32B and includes a second rib 344 extending downward D from the other end of the top rib 340. The communication passage 302 opens to the top rib 340.

[0076] In this embodiment, the oil scooped up by the fifth gear 76 is prevented from entering the front chamber 300 by the first rib 342 and the second rib 344 extending downward D from the top surface rib 340 .

[0077] Furthermore, the communication passage 302 communicating with the breather chamber 82 opens to the top surface rib 340. Therefore, the drive unit 10 can further suppress oil from entering the front chamber 300 compared to when the communication passage 302 opens at a position lower than the top surface rib 340.

[0078] (3) The wall surface of the vanguard chamber 300 includes a plate 350 having a vertical wall 352 disposed on the end face side of the top rib 340, the first rib 342, and the second rib 344, and a horizontal wall 354 extending from the lower edge of the vertical wall 352 toward the housing recess wall surface 32B serving as the mechanical wall surface. A gap 372 is formed between the end of the horizontal wall 354 of the plate 350 and the housing recess wall surface 32B serving as the mechanical wall surface.

[0079] In this embodiment, a gap 372 is formed between the side wall 354 of the plate 350 and the housing recess wall surface 32B, which serves as the mechanism wall surface. Therefore, air inside the mechanism accommodating portion 30 is taken into the front chamber 300 through the gap 372 and then sent to the breather chamber 82 via the communication passage 302.

[0080] This prevents oil in the mechanism housing section 30 from entering the vanguard chamber 300, while air in the mechanism housing section 30 is sent to the breather chamber 82 via the connecting passage 302, making it possible to discharge air while preventing oil from being blown out of the casing 12.

[0081] (4) The communication passage 302 opening into the top surface rib 340 opens at a position closer to the vertical wall 352 of the plate 350 than the housing recess wall surface 32B serving as the mechanism wall surface.

[0082] In the present embodiment, the communication passage 302 opens at a position closer to the vertical wall 352 of the plate 350 than to the housing recess wall surface 32B, which serves as the mechanical wall surface. Therefore, the drive unit 10 can promote the flow of air from the front chamber 300 to the communication passage 302, compared to when the communication passage 302 opens at the center of the top surface rib 340.

[0083] (5) One of the first rib 342 and the second rib 344 is set to a length that reaches the lower D side of the side wall 354 of the plate 350, and the other is set to a length that does not reach the side wall 354.

[0084] In this embodiment, the second rib 344, which is one of the first rib 342 and the second rib 344, has a length that reaches downward D beyond the side wall 354 of the plate 350. As a result, the second rib 344 blocks the opening of the front chamber 300 toward the rear (RR) of the vehicle. Therefore, even if oil scooped up by the fifth gear 76 is splashed onto the second rib 344, the drive unit 10 can prevent oil from entering the front chamber 300 using the second rib 344. During forward travel, the fifth gear 76 of the output shaft 58 rotates counterclockwise (CCW). Therefore, by setting the second rib 344 on the upstream side of the rotational direction to be longer downward than the first rib 342 and extending below the side wall 354, it is possible to prevent oil scooped up during forward travel from entering the front chamber 300. The downward protrusion lengths of the first rib 342 and the second rib 344 are such that the rib located upstream in the rotation direction of the output shaft 58 when the vehicle is moving forward is longer. This makes it possible to prevent oil from entering the front chamber 300 when the vehicle is moving forward, which is when the rotation speed is faster than when the vehicle is moving backward and the amount of oil scooped up tends to be greater.

[0085] The first rib 342, which is the other of the first rib 342 and the second rib 344, is set to a length that does not reach the side wall 354. As a result, in the front chamber 300, a front gap 374 that opens toward the vehicle front FR is formed between the end of the first rib 342 and the side wall 354. As a result, the drive unit 10 can promote the discharge of oil that has entered the front chamber 300 from the front gap 374 to the mechanism accommodating portion 30 by oil flowing from the vehicle rear RR toward the vehicle front FR.

[0086] (6) A guide portion 306 is provided on the outer periphery of the gear (76) provided on the output shaft 58 to guide the oil scooped up by the gear (76) toward one rib side of the front chamber 300.

[0087] The drive unit 10 of this embodiment is capable of guiding oil scooped up by the fifth gear 76, which is a gear provided on the output shaft 58, to the side of the vanguard chamber 300, which is closed by the second rib 344, which is one of the ribs.

[0088] Therefore, the drive unit 10 is able to suppress the infiltration of oil into the front chamber 300, compared to, for example, a case where the oil scooped up is guided to the bottom where the gap 372 and the rear gap 370 open.

[0089] (7) An oil reservoir 310 is provided in a portion D below the tip of the guide portion 306 located on one of the ribs by a recess formed in the housing recess wall surface 32B serving as a mechanism wall surface.

[0090] In this embodiment, an oil reservoir 310 is provided at the bottom of the tip of the guide portion 306, which serves as one of the ribs, so that the oil that is scooped up can be stored in the oil reservoir 310, thereby reducing the flow rate of the oil heading toward the vanguard chamber 300.

[0091] This reduces the force of oil flowing from the oil reservoir 310 toward the front chamber 300, making it possible to prevent oil from entering the front chamber 300.

[0092] (8) Between the front chamber 300 and the breather chamber 82, a flow passage 314 is formed, which allows the oil guided by the guide portion 306 to flow toward the intermediate shaft 56 side.

[0093] In the drive unit 10 of this embodiment, the oil guided by the guide portion 306 is allowed to flow toward the intermediate shaft 56 through a flow path 314 formed between the vanguard chamber 300 and the breather chamber 82, allowing it to be supplied to the third gear 70 and the fourth gear (not shown).

[0094] (9) The flow passage 314 is formed as a groove in the thick portion 380 of the housing recess wall surface 32B, which serves as a mechanical wall surface, and the communication passage 302 is formed as a tunnel in the thick portion 380.

[0095] The drive unit 10 of this embodiment can form the flow passage 314 by a groove formed in the thick portion 380 of the housing recess wall surface 32B, which serves as a mechanism wall surface. Also, the drive unit 10 can form the communication passage 302 by a tunnel formed in the thick portion 380.

[0096] (10) The recess 382 is formed in the housing recess wall surface 32B, which serves as a mechanism wall surface in the front chamber 300.

[0097] In the present embodiment, the volume of the front chamber 300 is increased by the recess 382. As a result, the drive unit 10 can reduce the amount of oil that flows toward the breather chamber 82 compared to when the volume of the front chamber 300 is small, and can further suppress the blowing of oil outside the casing 12.

[0098] (11) The bulging portion 384 that protrudes outward is formed on the rear side of the housing recess wall surface 32B, which serves as the mechanism wall surface on which the recess 382 is formed.

[0099] In the drive unit 10 of this embodiment, the bulging portion 384 that protrudes outward increases the rigidity of the housing 20, while the use of the bulging portion 384 makes it possible to increase the depth of the recess 382. This increases the volume of the front chamber 300, further improving the oil blowout suppression effect.

[0100] 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.

[0101] REFERENCE SIGNS LIST 10 Drive unit 12 Casing 20 Housing 22 Cover 30 Mechanism accommodating section 32B Housing recess wall surface 42B Case recess wall surface 50 Power transmission mechanism 52 Input shaft 56 Intermediate shaft 58 Output shaft 76 Fifth gear 82 Breather chamber 148 Ventilation pipe 300 Front chamber 302 Communication passage 306 Guide section 310 Oil reservoir section 314 Flow passage 340 Top rib 342 First rib 344 Second rib 350 Plate 352 Vertical wall 354 Horizontal wall 370 Rear gap 372 Gap 374 Front gap 380 Thick section 382 Recess 384 Bulging section D Downward U Upward

Claims

1. A drive device for driving drive wheels, comprising: a motor as a drive source; a power transmission mechanism that transmits power from the motor to the drive wheels; and a casing having a motor housing section that houses the motor and a mechanism housing section that houses the power transmission mechanism, wherein the power transmission mechanism has an input shaft to which power is input from the motor, an intermediate shaft that is arranged so as to be located higher than the input shaft when mounted on the vehicle and to which power is transmitted from the input shaft, and an output shaft that is arranged so as to be located lower than the intermediate shaft when mounted on the vehicle and transmits the power transmitted from the intermediate shaft to the drive wheels, wherein the mechanism housing section is provided with: a breather chamber that is arranged in an area located above the output shaft when mounted on the vehicle and has a passage that communicates with the outside; and a vanguard chamber that is arranged between the breather chamber and the output shaft, communicates with the breather chamber via a communication passage, and has a side wall that is interposed between the communication passage and the output shaft.

2. A drive unit as claimed in claim 1, wherein the wall surface of the vanguard chamber is configured to include: a top rib formed on the mechanism wall surface facing the power transmission mechanism in the mechanism accommodating section and extending along the breather chamber; a first rib formed on the mechanism wall surface and extending downward from one end of the top rib when mounted on the vehicle; and a second rib formed on the mechanism wall surface and extending downward from the other end of the top rib when mounted on the vehicle; and wherein the communication passage opens into the top rib.

3. A drive device as described in claim 2, wherein the wall surface of the vanguard chamber is configured to include a plate having a vertical wall arranged on the end face side of the top surface rib and the first rib and the second rib, and a horizontal wall extending from the lower edge of the vertical wall toward the mechanism wall surface, and a gap is formed between the end of the horizontal wall of the plate and the mechanism wall surface.

4. A drive device according to claim 3, wherein the communication passage opening in the top surface rib opens at a position closer to the vertical wall of the plate than to the mechanism wall surface.

5. A drive device as claimed in claim 3, wherein one of the first rib and the second rib is set to a length that reaches below the side wall of the plate when the plate is mounted on the vehicle, and the other is set to a length that does not reach the side wall.

6. A drive device as claimed in claim 5, wherein a guide portion is provided on the outer periphery of the gear provided on the output shaft to guide oil scooped up by the gear towards the one rib side of the vane chamber.

7. A drive unit according to claim 6, wherein an oil reservoir is provided by a recess formed in the wall surface of the mechanism at a position below the tip of the guide section located on the one rib side when the drive unit is mounted on the vehicle.

8. A drive unit according to claim 6, wherein a flow path is formed between the front chamber and the breather chamber, for allowing oil guided by the guide portion to flow toward the intermediate shaft.

9. A drive device according to claim 8, wherein the flow passage is constituted by a groove formed in a thick portion of the wall surface of the mechanism, and the communication passage is constituted by a tunnel formed in the thick portion.

10. A drive device according to claim 2, wherein a recess is formed in the mechanism wall surface in the vanguard chamber.

11. A drive device according to claim 10, wherein a bulge that protrudes outward is formed on the back side of the mechanism wall surface on which the recess is formed.

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