VEHICLE POWER TRANSMISSION DEVICE

Abstract

Vehicle power transmission device comprising a gearbox housing (16, 17), a differential gear (13) received in a front part of the gearbox housing (16, 17), a bearing (32) which supports the differential gear (13) on a side wall (17a) of the gearbox housing (16, 17), a final output gear (29) provided on an outer circumference of the differential gear (13), and a final drive gear (28) which transmits a drive force from a drive source (11) via an input shaft (20) to the final output gear (29), wherein the final output gear (29) is arranged on a front side in a direction of travel of the vehicle with respect to the input shaft (20), characterized by the fact that the side wall (17a) in front of a tooth engagement (38) of the final output gear (29) and the final drive gear (28) is provided with an oil collection recess (50) which collects oil taken up by the final output gear (29) from a lower part of the gearbox housing (16, 17) and supplies the oil to the bearing (32), and a motor housing (15) which accommodates an electric motor (11) as the drive source inside, is connected to the gearbox housing (16, 17), and a connecting bore (16b) which provides communication between an interior of the motor housing (15) and an interior of the gearbox housing (16, 17), is formed lower than the level of oil accumulated in the lower part of the gearbox housing (16, 17).

Description

[0001] The present invention relates to a vehicle power transmission device in which a bearing supporting a differential gear housed in a front part of a transmission case is lubricated with oil received from a final driven gear provided on the differential gear.

[0002] An axle drive device that transmits the rotation of a motor shaft of an electric motor to a differential gear via a countershaft drive gear provided on the motor shaft, a countershaft driven gear provided on a countershaft, a final drive gear provided on the countershaft, and a final driven gear provided on a differential shaft is known from document JP 2005 - 201 316 A.

[0003] US 2010 / 0 083 792 A1 discloses a vehicle power transmission device according to the preamble of claim 1 and claim 2. EP 1 544 510 A2 discloses another vehicle power transmission device. Furthermore, JP 2005-106 178 A, JP 2015-048 890 A, JP 2015-068 466 A, JP 2017-089 727 A, and WO 2017 / 153 646 A1 all disclose an oil collecting recess for lubricating a differential bearing. US 2010 / 0 083 792 A1 further discloses an oil guide wall and an oil pump arranged coaxially with the input shaft. DE 1 801 917 A discloses an oil guide wall with an opening.

[0004] In the conventional final drive device, since the differential gear is disposed in a front part of the transmission case, even if it is attempted to lubricate a part to be lubricated by taking up oil accumulated in a lower part of the transmission case upwardly and rearwardly by means of the final driven gear provided on the differential gear after a rear part of the final driven gear is engaged with a front part of the final drive gear, the corresponding problem in which oil taken up by the final driven gear is difficult to reach a part to be lubricated because it is prevented from doing so by the meshing of the final driven gear and the final drive gear is addressed by taking up oil upwardly and rearwardly by means of the counter driven gear provided on the countershaft to thereby supply the oil to the part to be lubricated.

[0005] However, in such a method, since it is necessary to increase the diameter of the countershaft output gear, there is a problem that the vertical dimension of the transmission case increases.

[0006] The present invention has been made in light of the above circumstances, and an object of the invention is to effectively lubricate a bearing supporting a differential gear housed in a front part of a transmission case with oil received from a final driven gear provided on the differential gear.

[0007] To achieve the above object, according to a first aspect of the present invention, there is provided a vehicle power transmission device including a transmission case, a differential gear housed in a front part of the transmission case, a bearing supporting the differential gear on a side wall of the transmission case, a final driven gear provided on an outer periphery of the differential gear, and a final drive gear transmitting a driving force of a drive source to the final driven gear via an input shaft, wherein the final driven gear is arranged on a front side in a traveling direction of the vehicle with respect to the input shaft, wherein the side wall in front of a meshing position of the final driven gear and the final drive gear is provided with an oil collecting recessed part that collects oil received by the final driven gear from a lower part of the transmission case and supplies the oil to the bearing.Furthermore, a motor housing accommodating an electric motor as the drive source in its interior is connected to the transmission case, and a communication hole for communication between an interior of the motor housing and an interior of the transmission case is formed lower than the level of the oil accumulated in the lower part of the transmission case.

[0008] To achieve the above object, according to a second aspect of the present invention, there is provided a vehicle power transmission device including a transmission case, a differential gear housed in a front part of the transmission case, a bearing supporting the differential gear on a side wall of the transmission case, a final driven gear provided on an outer periphery of the differential gear, and a final drive gear transmitting a driving force of a drive source to the final driven gear via an input shaft, wherein the final driven gear is arranged on a front side in a traveling direction of the vehicle with respect to the input shaft, wherein the side wall in front of a meshing position of the final driven gear and the final drive gear is provided with an oil collecting recessed part that collects oil received by the final driven gear from a lower part of the transmission case and supplies the oil to the bearing.Furthermore, the oil collecting recess part, which is arranged further forward than the center of the final driven gear, is formed to have a groove-shaped cross section with a bottom wall extending radially inward toward the bearing, a front inclined wall connected to a front side of the bottom wall and inclined at a first inclination angle, and a rear inclined wall connected to a rear side of the bottom wall and inclined at a second inclination angle, the second inclination angle being smaller than the first inclination angle.

[0009] According to a third aspect of the present invention, in addition to the second aspect, a width of the bottom wall further decreases as it extends toward the bearing.

[0010] Further, according to a fourth aspect of the present invention, in addition to the second or third aspect, an angle formed by a slope start line of the rear inclined wall forming a rear edge of the groove-shaped cross section with respect to a rearward horizontal direction is set to at least 90° when the vehicle ascends an incline having a maximum slope angle, and an angle formed by a slope start line of the front inclined wall forming a front edge of the groove-shaped cross section with respect to the rearward horizontal direction is set to at most 170° when the vehicle descends a slope having a maximum slope angle.

[0011] According to a fifth aspect of the present invention, in addition to any one of the first to fourth aspects, the device further comprises an oil guide wall arranged to follow a lower rear part of the final driven gear, and the tooth engagement between the oil collecting recess part and the oil guide wall is positioned in the horizontal direction.

[0012] Furthermore, according to a sixth aspect of the present invention, in addition to the fifth aspect, the device comprises an oil pump arranged in a lower part of the transmission case, and the oil guide wall is arranged between a first space accommodating the final driven gear and a second space accommodating the oil pump.

[0013] Furthermore, according to a seventh aspect of the present invention, in addition to the sixth aspect, an oil level accumulated in the lower part of the transmission case is positioned lower than an upper end of the oil guide wall, and an opening providing communication between the first space and the second space is formed in a lower part of the oil guide wall.

[0014] According to an eighth aspect of the present invention, in addition to the seventh aspect, the opening is further positioned higher than a lower end of the final driven gear.

[0015] An electric motor 11 of an embodiment corresponds to the drive source of the present invention, a left housing 15 of the embodiment corresponds to the motor housing of the present invention, a middle housing 16 and a right housing 17 of the embodiment correspond to the gear housing of the present invention, and a tapered roller bearing 32 of the embodiment corresponds to the bearing of the present invention.

[0016] According to the first and second aspects of the present invention, the vehicle power transmission device includes the transmission case, the differential gear is housed in a front part of the transmission case, the bearing supports the differential gear on the side wall of the transmission case, the final driven gear is provided on the outer periphery of the differential gear, and the final drive gear transmits the driving force of the drive source to the final driven gear via the input shaft, and the final driven gear is arranged on the front side in the traveling direction of the vehicle with respect to the input shaft.

[0017] Since the side wall in front of the meshing portion of the final driven gear and the final drive gear is provided with the oil collecting recessed portion which collects oil taken in by the final driven gear from the lower part of the transmission case and supplies it to the bearing, even if it is more difficult for the oil taken in by the final driven gear to reach the bearing because it is obstructed by the meshing portion of the final driven gear and the final drive gear, it is possible to effectively lubricate the bearing by efficiently collecting the oil that has flowed through the meshing portion of the final driven gear and the final drive gear and supplying it to the bearing.

[0018] Further, according to the fifth aspect of the present invention, since it has the oil guide wall arranged to follow a lower rear part of the final driven gear, and the meshing between the oil collecting recess part and the oil guide wall is positioned in the horizontal direction, even when it is difficult for the oil picked up by the final driven gear to reach the bearing due to the interference of the meshing, it is possible to supply the oil picked up by the final driven gear forward along the oil guide wall and efficiently supply it to the oil collecting recess part, thereby lubricating the bearing.

[0019] Furthermore, according to the sixth aspect of the present invention, since it has the oil pump arranged in a lower part of the transmission case and the oil guide wall is arranged between the first space accommodating the final driven gear and the second space accommodating the oil pump, the oil guide wall functions as a baffle plate, thereby suppressing ripples in the oil level generated by rotation of the differential gear and thereby preventing air from being sucked in by the oil pump.

[0020] According to the seventh aspect of the present invention, since the level of oil accumulated in the lower part of the transmission case is positioned lower than the upper end of the oil guide wall and the opening establishing communication between the first housing part and the second housing part is formed in a lower part of the oil guide wall, the first housing part and the second housing part, which are separated by the oil guide wall, can be communicated with each other via the opening, the height of the oil level between the first housing part and the second housing part can be unified, and furthermore, it is possible to make it difficult for the oil to include air when passing through the opening, thereby preventing the generation of bubbles.

[0021] Furthermore, according to the eighth aspect of the present invention, since the opening is positioned higher than the lower end of the final driven gear, it is possible to form the opening without bulging the lower part of the gear case downward, thereby preventing an increase in the size of the gear case.

[0022] Further, according to the first aspect of the present invention, since the motor housing accommodating the electric motor as a drive source therein is connected to the transmission case, and the communication hole providing communication between an interior space of the motor housing and an interior space of the transmission case is formed lower than the level of oil accumulated in the lower part of the transmission case, even if the oil of the interior space of the transmission case flows out into the interior space of the motor housing via the communication hole, it is possible to reliably lubricate the bearing with the oil in the transmission case by the oil collecting action of the oil collecting recess part.

[0023] According to the second aspect of the present invention, since the oil collecting recess part, which is located further forward than the center of the final driven gear, is formed to have a groove-shaped cross section, while the bottom wall extends radially inward toward the bearing, the front inclined wall is connected to the front side of the bottom wall and inclined at a first inclination angle, and the rear inclined wall is connected to the rear side of the bottom wall and inclined at a second inclination angle, the second inclination angle being smaller than the first inclination angle, it is further possible to efficiently guide the oil to the bottom wall part of the oil collecting recess part by means of the rear inclined wall having a small inclination angle and to shut off the oil by means of the front inclined wall having a large inclination angle, whereby the oil can be effectively supplied to the bearing.

[0024] Further, according to the third aspect of the present invention, since the width of the bottom wall decreases toward the bearing, it is possible to guide the oil collected in the oil collecting recess part to the bearing, thereby being able to supply it efficiently.

[0025] Furthermore, according to the fourth aspect of the present invention, since the angle formed by the inclination start line of the rear inclined wall forming the rear edge of the groove-shaped cross section with respect to the rear horizontal direction is set to at least 90° when the vehicle climbs an incline with a maximum inclination angle, and the angle formed by the inclination start line of the front inclined wall forming the front edge of the groove-shaped cross section with respect to the rear horizontal direction is set to at most 170° when the vehicle descends a slope with a maximum inclination angle, it is possible to reliably supply oil to the bearing even when the vehicle climbs an incline or descends a slope. Fig. Figure 1 shows a vertical sectional view of a drive unit of a motor vehicle (a sectional view taken along the line 1-1 in Fig. 2). (first embodiment) Fig. 2 shows a view from the arrow line 2-2 in Fig. 1. (first embodiment) Fig. 3 shows a view from the arrow line 3-3 in Fig. 1. (first embodiment) Fig. Figure 4 shows an enlarged sectional view taken along line 4-4 in Fig. 3. (first embodiment) Fig. Figure 5 is a diagram illustrating the operation when the motor vehicle climbs an incline and descends a decline (first embodiment).

[0026] An embodiment of the present invention will be described below with reference to Fig. 1 to Fig. 5 explained.

[0027] As in Fig. 1 and Fig. As shown in Figure 2, a drive unit of an electric vehicle includes a motor housing 14 accommodating an electric motor 11, a reduction gear 12, and a differential gear 13. The motor housing 14 is divided into three parts in the vehicle width direction and includes a left housing 15, a middle housing 16, and a right housing 17. A first housing portion 43 is defined between the left housing 15 and the middle housing 16, and a second housing portion 44 is defined between the middle housing 16 and the right housing 17.

[0028] The electric motor 11, which is arranged in the first housing part 43, has a motor shaft 20 supported on the left housing 15 and the middle housing 16 via ball bearings 18 and 19, respectively, a rotor 21 fixed to the motor shaft 20, and a stator 22 fixed to the middle housing 16 to surround the outer periphery of the rotor 21. Oil is stored in a lower part of the motor housing 14, with the oil level designated OL.

[0029] The reduction gear 12, which is arranged in the second housing part 44, has a first reduction gear 23 which is fixedly provided on one end of the motor shaft 20 projecting to the right from the middle housing 16, a speed reduction shaft 26 which is supported on the middle housing 16 and the right housing 17 via tapered roller bearings 24 and 25, respectively, a second reduction gear 27 which is fixedly provided on the speed reduction shaft 26 and meshes with the first reduction gear 23, a final drive gear 28 which is fixedly provided on the speed reduction shaft 26, and a final driven gear 29 which is fixedly provided on the outer periphery of the differential gear 13 and meshes with the final drive gear 28.

[0030] A differential case 30, which forms the outer skin of the differential gear 13 arranged in the second housing part 44, is supported on the middle case 16 and the right case 17 via tapered roller bearings 31 and 32, respectively. An inner joint 34 provided at the end of a long left output shaft 33 extending to the left of the differential case 30 protrudes outward from the left case 15, and an inner joint 36 provided at the end of a short right output shaft 35 extending to the right of the differential case 30 protrudes outward from the right case 17. The left inner joint 34 is connected to a left rear wheel via a left half shaft (not shown), and the right inner joint 36 is connected to a right rear wheel via a right half shaft (not shown).The left end of the left output shaft 33, the right end of which is supported on the differential gear 13, is mounted on the left housing 15 via a ball bearing 37.

[0031] As from Fig. 2, a communication hole 16b is formed in a side wall 16a of the middle housing 16, which divides the first housing part 43 and the second housing part 44, the communication hole 16b providing communication between the first housing part 43 and the second housing part 44 at a position below the oil level OL. An oil pump 45 and an oil strainer 46 are arranged to be vertically stacked in a lower rear part of the second housing part 44, and an arcuate oil guide wall 16c is formed along the outer periphery of the final driven gear 29 to define a first space 47 on the front side accommodating the differential gear 13 and a second space 48 on the rear side accommodating the oil pump 45 and the oil strainer 46. An opening 49 providing communication between the first space 47 and the second space 48 is formed below the lower end of the oil guide wall 16c.

[0032] Fig. 3 shows a left side surface of the right housing 17, which is connected to a right side surface of the middle housing 16. Formed in a side wall 17a of the right housing 17 are a circular recessed portion 17b covering a right side surface of the differential gear 13, a support hole 17c formed in the center of the recessed portion 17b and into which the tapered roller bearing 32 supporting the right end of the differential gear 13 is fitted, and an oil collecting recessed portion 50 formed by depressing a part of the recessed portion 17b into a groove shape. The oil collecting recessed portion 50 extends obliquely upward from the center of the differential gear 13 toward the front side toward the radially outer side.

[0033] As detailed in Fig. 3 and Fig. 4, the oil collecting recessed part 50 is formed into a groove-shaped cross section and includes a flat bottom wall 50a, a front inclined wall 50b extending obliquely forward from the front end of the bottom wall 50a and connected to a wall surface of the recessed portion 17b of the right housing 17, and a rear inclined wall 50c extending obliquely rearward from the rear end of the bottom wall 50a and connected to the wall surface of the recessed portion 17b of the right housing 17. The bottom wall 50a has a width that gradually decreases from the radially outer side to the inner side, and the radially inner end is connected to the bearing bore 17c.

[0034] When the inclination angle of the front inclined wall 50b with respect to a plane (a split surface of the right case 17) orthogonal to the axis of the differential gear 13 is a first inclination angle θ1, and the inclination angle of the rear inclined wall 50c is a second inclination angle θ2, the second inclination angle θ2 is set to be smaller than the first inclination angle θ1. That is, the front inclined wall 50b is upright with respect to the split surface of the right case 17, and the rear inclined wall 50c is recumbent with respect to the split surface of the right case 17.

[0035] The operation of the embodiment of the present invention having the above arrangement will be explained below.

[0036] Since the first housing part 43 defined between the left housing 15 and the middle housing 16 of the motor housing 14 and the second housing part 44 defined between the middle housing 16 and the right housing 17 of the motor housing 14 are caused to communicate with each other via the communication hole 16b formed in the middle housing 16, the oil accumulated in the second housing part 44 is supplied to the first housing part 43 so as to be used for lubricating and cooling the electric motor 11.

[0037] When the level of oil accumulated in the second housing part 44 varies depending on the running vehicle because oil of the first space 47 on the front side and the second space 48 of the second housing part 44 moves back and forth via the opening 49, the oil level OL can be uniformed between the first space 47 and the second space 48 on the rear side. With this arrangement, since the opening 49 is at a much lower position than the oil level OL, it is possible to make it difficult for the oil to trap air when passing through the opening 49, thereby preventing the formation of bubbles. Furthermore, since the opening 49 is positioned higher than the lower end of the final driven gear 29, it is possible to form the opening 49 without bulging the lower part of the middle housing 16 downward, thereby preventing an increase in the size of the motor housing 14.

[0038] The oil guide wall 16c, which is arranged between the first space 47 accommodating the oil pump 45 and the second space 48 accommodating the final drive gear 29, acts as a baffle plate so that ripples in the oil level generated by rotation of the differential gear 13 are suppressed and thereby prevent air from being sucked in by the oil pump 45.

[0039] Due to the oil guide wall 16c arranged along the lower rear part of the final driven gear 29, the final driven gear 29 can supply the collected oil forward along the oil guide wall 16c and the oil collecting recess part 50 of the side wall 17a of the right housing 17.

[0040] Since the second inclination angle θ2 of the rear inclined wall 50c of the oil collecting recess portion 50 is small, oil is smoothly supplied to the rear inclined wall 50c, reaches the bottom wall 50a, is blocked by the front inclined wall 50b with the large first inclination angle θ1, flows radially inward along the bottom wall 50a, passes through the bearing bore 17c, and lubricates the tapered roller bearing 32 that supports the right end portion of the differential gear 13 to the right case 17. In this arrangement, since the width of the bottom wall 50a of the oil collecting recess portion 50 decreases toward the tapered roller bearing 32, oil collected by the oil collecting recess portion 50 can be guided to the tapered roller bearing 32 and efficiently supplied thereto.

[0041] Since the differential gear 13 is arranged in the front part of the engine housing 14 and a tooth engagement 38 (see Fig. 2) of the final drive gear 28 and the final driven gear 29 is positioned in the path through which oil taken up by the final driven gear 29 along the oil guide wall 16c is supplied to the tapered roller bearing 32, there is a possibility that the supply of oil is hindered by the tooth mesh 38 and it becomes difficult for the oil to flow to the oil collecting recess part 50.

[0042] However, according to the present embodiment, since oil is actively collected by the oil collecting recessed part 50 and supplied to the tapered roller bearing 32, even if the supply of oil is hindered by the gear mesh 38 of the final drive gear 28 and the final driven gear 29, a required amount of oil can be supplied to the tapered roller bearing 32 to compensate for this.

[0043] The first housing part 43 and the second housing part 44 of the motor housing 14 are provided for communication via the communication hole 16b, which is lower than the oil level OL, oil of the second housing part 44 flows out to the first housing part 43 to lubricate and cool the electric motor 11 even if the oil amount of the second housing part 44 is reduced, the reduction in the oil amount is compensated by the effect of collecting oil by the oil collecting recess part 50, and a required amount of oil can be supplied to the tapered roller bearing 32.

[0044] Fig. 5 (A) shows a state in which the vehicle climbs an incline with an expected maximum incline angle δ. In this case, since the engine casing 14 is tilted upward and forward, a slope start line 50e, which is the rear edge of the rear inclined wall 50c of the oil collecting recess part 50, is tilted rearward, and an angle α formed by the slope start line 50e with respect to the rearward horizontal direction is set to at least 90°. Consequently, even when the vehicle climbs an incline with the expected maximum incline angle δ, oil forced downward by gravity can be reliably introduced into the oil collecting recess part 50.

[0045] Fig.5(B) shows a state in which the vehicle descends a slope with an expected maximum slope angle δ. In this case, since the engine casing 14 is tilted downward and forward, a slope start line 50d, which is the leading edge of the front inclined wall 50b of the oil collecting recess portion 50, is tilted forward, and an angle β formed by the slope start line 50d with respect to the rearward horizontal direction is set to 170° or less. Consequently, even when the vehicle descends a slope with the expected maximum slope angle δ, the front inclined wall 50b of the oil collecting recess portion 50 is tilted downward toward the tapered roller bearing 32 at an angle of 10° or more, and the oil collected in the oil collecting recess portion 50 can be smoothly supplied to the tapered roller bearing 32.

[0046] An embodiment of the present invention is explained above, but the present invention can be modified in various ways as long as the modifications do not depart from the subject matter.

[0047] For example, the bearing of the present invention is not limited to the tapered roller bearing 32 of the embodiment and may be any type of bearing.

[0048] Furthermore, the drive source of the present invention is not limited to the electric motor 11 of the embodiment and may be any type of drive source such as a motor. EXPLANATION OF REFERENCE SIGNS AND SYMBOLS: 11 Electric motor (power source) 13 differential gears 15 Left housing (engine housing) 16 Middle housing (gearbox housing) 16b connecting hole 16c Oil guide wall 17 Right housing (gearbox housing) 17a side wall 20 Input shaft 28 Final drive gear 29 Final drive gear 32 angular contact roller bearings (bearings) 38 tooth engagement 45 Oil pump 47 First Room 48 Second Room 49 Opening 50 Oil collecting recess part 50a floor wall 50b Front inclined wall 50c Rear Inclined Wall 50d Initial slope line of the front inclined wall 50e Initial slope line of the rear inclined wall θ1 first inclination angle θ2 second inclination angle α Angle formed by the initial slope line of the rear inclined wall with respect to the horizontal direction to the rear β Angle formed by the initial slope line of the front inclined wall with respect to the horizontal direction to the rear

Claims

[1] A vehicle power transmission device comprising a transmission housing (16, 17), a differential gear (13) accommodated in a front part of the transmission housing (16, 17), a bearing (32) which supports the differential gear (13) on a side wall (17a) of the transmission housing (16, 17), a final driven gear (29) provided on an outer circumference of the differential gear (13), and a final drive gear (28) which transmits a driving force of a drive source (11) via an input shaft (20) to the final driven gear (29), wherein the final driven gear (29) is arranged on a front side in a direction of travel of the vehicle with respect to the input shaft (20), characterized by , that the side wall (17a) is provided with an oil collecting recess (50) in front of a tooth engagement (38) of the final driven gear (29) and the final drive gear (28), which collects oil taken up by the final driven gear (29) from a lower part of the gear housing (16, 17) and supplies the oil to the bearing (32), and a motor housing (15) accommodating therein an electric motor (11) as the drive source, is connected to the transmission case (16, 17), and a communication hole (16b) providing communication between an interior of the motor housing (15) and an interior of the transmission case (16, 17) is formed lower than the level of oil accumulated in the lower part of the transmission case (16, 17). [2] A vehicle power transmission device comprising a transmission housing (16, 17), a differential gear (13) accommodated in a front part of the transmission housing (16, 17), a bearing (32) which supports the differential gear (13) on a side wall (17a) of the transmission housing (16, 17), a final driven gear (29) provided on an outer circumference of the differential gear (13), and a final drive gear (28) which transmits a driving force of a drive source (11) via an input shaft (20) to the final driven gear (29), wherein the final driven gear (29) is arranged on a front side in a direction of travel of the vehicle with respect to the input shaft (20), characterized by , that the side wall (17a) is provided with an oil collecting recess (50) in front of a tooth engagement (38) of the final driven gear (29) and the final drive gear (28), which collects oil taken up by the final driven gear (29) from a lower part of the gear housing (16, 17) and supplies the oil to the bearing (32), and the oil collecting recessed part (50) which is arranged further forward than the center of the final driven gear (29) is formed to have a groove-shaped cross section, while having a bottom wall (50a) extending radially inward toward the bearing (32), a front inclined wall (50b) which is connected to a front side of the bottom wall (50a) and inclined at a first inclination angle (θ1), and a rear inclined wall (50c) which is connected to a rear side of the bottom wall (50a) and inclined at a second inclination angle (θ2), wherein the second inclination angle (θ2) is smaller than the first inclination angle (θ1). [3] A vehicle power transmission device according to claim 2, wherein a width of the bottom wall (50a) decreases toward the bearing (32). [4] A vehicle power transmission device according to claim 2 or claim 3, wherein an angle (α) formed by a slope start line (50e) of the rear inclined wall (50c) forming a rear edge of the groove-shaped cross section with respect to a horizontal rearward direction is set to at least 90° when the vehicle ascends an incline having a maximum slope angle, and an angle (β) formed by a slope start line (50d) of the front inclined wall (50b) forming a front edge of the groove-shaped cross section with respect to the horizontal rearward direction is set to at most 170° when the vehicle descends a slope having a maximum slope angle. [5] A vehicle power transmission device according to any one of claims 1 to 4, wherein the device comprises an oil guide wall (16c) arranged to follow a lower rear part of the final driven gear (29), and the tooth engagement (38) between the oil collecting recess part (50) and the oil guide wall (16c) is positioned in the horizontal direction. [6] A vehicle power transmission device according to claim 5, wherein the device comprises an oil pump (45) arranged in a lower part of the transmission case (16, 17), and the oil guide wall (16c) is arranged between a first space (47) accommodating the final driven gear (29) and a second space (48) accommodating the oil pump (45). [7] A vehicle power transmission device according to claim 6, wherein a level of oil accumulated in the lower part of the transmission case (16, 17) is positioned lower than an upper end of the oil guide wall (16c), and an opening (49) providing communication between the first space (47) and the second space (48) is formed in a lower part of the oil guide wall (16c). [8] A vehicle power transmission device according to claim 7, wherein the opening (49) is positioned higher than a lower end of the final driven gear (29).

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