Transmission device

Abstract

Provided is a transmission device that can suppress a degradation in the lubrication of a bearing when a vehicle is in backward travel. One aspect of the present disclosure is a transmission device comprising a transmission mechanism and a gear case that accommodates the transmission mechanism. The transmission mechanism has an input gear, a counter gear, and a ring gear. The counter gear has a first gear and a second gear. The center of rotation of the counter gear is positioned higher than the center of rotation of the input gear and the center of rotation of the ring gear. The gear case has: a catch tank; a main guide that feeds, to the catch tank, oil that has been scooped up by the ring gear when the ring gear is rotating in a first direction; and a reverse guide that feeds, to the catch tank, oil that has been scooped up by the first gear when the ring gear is rotating in a second direction.

Description

[Technical Field]

[0001] The present disclosure relates to a transmission. [Background technology]

[0002] In a transmission device having a differential mechanism, a structure is known in which oil for lubricating the bearings scooped up by the ring gear is supplied to the bearings of each gear regardless of the direction of rotation of the ring gear (i.e., the direction of travel of the vehicle) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-502614 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned transmission does not take into consideration the rotational speed of the ring gear when the vehicle is moving backward. That is, when the vehicle is moving backward, the rotational speed of the ring gear is slower than when the vehicle is moving forward, so the amount of oil scooped up by the ring gear is also smaller. As a result, there is a risk that the amount of oil supplied to the bearings will be insufficient.

[0005] It is preferable that one aspect of the present disclosure provides a transmission device that can suppress a decrease in lubrication of a bearing when a vehicle is moving backward. [Means for solving the problem]

[0006] One aspect of the present disclosure is a transmission device including a transmission mechanism and a gear case that houses the transmission mechanism. The transmission mechanism includes an input gear, a counter gear having a rotational axis parallel to the rotational axis of the input gear, a ring gear having a rotational axis parallel to the rotational axis of the input gear, a differential case fixed to the ring gear, a differential mechanism disposed inside the differential case, an input gear bearing that rotatably supports the input gear, a counter gear bearing that rotatably supports the counter gear, and a differential case bearing that rotatably supports the differential case.

[0007] The counter gear has a first gear that meshes with the input gear, and a second gear that has a smaller outer diameter than the first gear, is arranged concentrically with the first gear, and meshes with the ring gear. The rotation axis of the counter gear is located above the rotation axis of the input gear and the rotation axis of the ring gear.

[0008] The gear case has a lower guide that faces the ring gear from the radial outside at a position lower than the rotational axis of the ring gear and faces the first gear from the radial outside at a position lower than the rotational axis of the first gear, a catch tank that is arranged in a position that overlaps the input gear from above, a main guide that sends oil scooped up by the ring gear to the catch tank when the ring gear rotates in a first direction, and a reverse guide that sends oil scooped up by the first gear after being scooped up by the ring gear to the catch tank when the ring gear rotates in a second direction opposite to the first direction.

[0009] The reverse guide is positioned so that it overlaps with the first gear in the axial direction of the counter gear. The first gear is a helical gear that is twisted so that oil is sent toward the reverse guide when the first gear rotates in the second direction.

[0010] With this configuration, when the ring gear rotates in the second direction, oil is sent to the reverse guide due to the upward movement of the first gear and the twisting of the first gear. This allows the oil to be supplied to the catch tank via the reverse guide. This prevents a decrease in the lubrication of the bearing when the rotational speed of the ring gear in the second direction is low (i.e., when the vehicle is moving backward).

[0011] In one aspect of the present disclosure, the gear case may have a first case and a second case that sandwich the transmission mechanism in the axial direction of the input gear. The reverse guide may be a rib that protrudes from the inner surface of the second case in the axial direction of the input gear and may have a guide surface along which oil flows toward the catch tank. The guide surface may have a width that is perpendicular to the oil flow direction that increases toward the catch tank. This configuration reduces the cost of forming the reverse guide. Furthermore, by increasing the width of the guide surface toward the catch tank, oil that is sent toward the inner surface of the second case due to twisting of the first gear can be efficiently sent to the catch tank.

[0012] In one aspect of the present disclosure, the reverse guide may have an upstream end and a downstream end in the oil flow direction. The upstream end may be positioned higher than the downstream end. With this configuration, oil that reaches the reverse guide is more likely to flow toward the catch tank. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic right side view of a transmission device according to an embodiment, with a second case and some bearings removed. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic left side view of the transmission device of FIG. 1 with a first case and some bearings removed. [Figure 5]FIG. 5 is a schematic right side view of the first case of FIG. [Figure 6] FIG. 6 is a schematic left side view of the second case of FIG. [Figure 7] FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a schematic cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is a schematic cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a schematic cross-sectional view taken along the line XX in FIG. [Figure 11] FIG. 11 is a schematic left side view of the second case of FIG. [Figure 12] FIG. 12 is a schematic right side view of the first case of FIG. [Explanation of symbols]

[0014] 1...transmission device, 2...transmission mechanism, 3...gear case, 3A...first case, 3B...second case, 21...input gear, 22...counter gear, 23...Ring gear, 24...Differential case, 31...Catch tank, 32...Main guide, 33...Guidance section, 34...Dropping wall, 35...Buffer section, 36...lower guide, 37...reverse guide, 221...first gear, 222... second gear, 311... bottom wall, 311A, 311B... communication holes, 312...Side wall, 312A...Outflow part, 321...Upstream end, 322...Downstream end, 323... guide surface, 323A... groove, 331... first end, 332... second end, 351...bottom wall, 352...side wall, 352A...outlet, 371...upstream end, 372...downstream end, 373...guide surface. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings. [1. First embodiment] [1-1.Configuration] The transmission device 1 shown in FIG. 1 is installed in an automobile and transmits power from a drive source of the automobile to the wheels.

[0016] The transmission device 1 includes a transmission mechanism 2, a gear case 3, and a parking lock mechanism 5. The transmission device 1 is installed in the automobile in an orientation in which the direction parallel to the rotation axis L1 of the input gear 21 of the transmission mechanism 2 is the left-right direction, and the direction in which the input gear 21 is arranged relative to the ring gear 23 is the forward direction.

[0017] <Transmission mechanism> The power transmission mechanism 2 has an input gear 21 , a counter gear 22 , a ring gear 23 , a differential case 24 , and a differential mechanism 25 .

[0018] Furthermore, as shown in FIG. 2, the transmission mechanism 2 has a first input gear bearing 27A, a second input gear bearing 27B, a first counter gear bearing 28A, a second counter gear bearing 28B, a first differential case bearing 29A, and a second differential case bearing 29B.

[0019] <Input gear> The input gear 21 is an external gear that is drivingly connected to a motor (not shown) and rotates around its axis by the driving force of the motor.

[0020] The input gear 21 rotates counterclockwise in Fig. 1 when the vehicle moves forward, and rotates clockwise in Fig. 1 when the vehicle moves backward. A rotation axis L1 of the input gear 21 is parallel to the left-right direction.

[0021] The input gear 21 is a right-hand helical gear. As shown in Figure 2, a leftward thrust load F1 is generated in the input gear 21 when the automobile is driven forward.

[0022] <Counter gear> The counter gear 22 has a rotation axis L2 that is parallel to the rotation axis L1 of the input gear 21.

[0023] The rotation axis L2 of the counter gear 22 is located rearward of the rotation axis L1 of the input gear 21 and above the rotation axis L1 of the input gear 21 and the rotation axis L3 of the ring gear 23 (see FIG. 1). The counter gear 22 has a first gear 221 and a second gear 222.

[0024] The first gear 221 is an external gear that meshes with the input gear 21. The first gear 221 is a left-handed helical gear. A rightward thrust load F2 is generated in the first gear 221 when the automobile is driven forward.

[0025] Due to the twist of the first gear 221, when the first gear 221 rotates in the reverse direction of the vehicle, the oil scooped up by the first gear 221 is sent in the left direction.

[0026] That is, the first gear 221 is twisted so that when the first gear 221 rotates in the reverse direction of the automobile, the oil is sent toward the inner surface of the second case 3B and the reverse guide 37 provided on the inner surface.

[0027] The second gear 222 is an external gear that meshes with the ring gear 23. The second gear 222 has a smaller outer diameter than the first gear 221 and is disposed concentrically with the first gear 221. The second gear 222 is disposed to the right of the first gear 221.

[0028] The second gear 222 is a left-hand helical gear. The second gear 222 rotates integrally with the first gear 221. A left-hand thrust load F3 is generated on the second gear 222 when the vehicle is driven forward. The second gear 222 has a stepped portion 222A that comes into axial contact with the first gear 221. The thrust load F2 of the first gear 221 is received by the stepped portion 222A of the second gear 222. The thrust load F2 of the first gear 221 and the thrust load F3 of the second gear 222 cancel each other out, thereby reducing the thrust loads acting on the first counter gear bearing 28A and the second counter gear bearing 28B.

[0029] <Ring gear> The ring gear 23 is an external gear having a rotation axis L3 parallel to the rotation axis L1 of the input gear 21. The rotation axis L3 of the ring gear 23 is located rearward of the rotation axis L2 of the counter gear 22.

[0030] The ring gear 23 rotates the differential case 24 by the rotational force transmitted from the counter gear 22 , and also scoops up the lubricating oil accumulated at the bottom of the gear case 3 toward the main guide 32 .

[0031] The ring gear 23 is a right-hand helical gear. When the vehicle is driven forward, a rightward thrust load F4 is generated on the ring gear 23. This thrust load F4 is received by the flange 242 of the differential case 24.

[0032] Furthermore, due to the twist of the ring gear 23, when the ring gear 23 rotates in the forward direction of the automobile, the oil scooped up by the ring gear 23 is sent in the right direction.

[0033] In other words, the ring gear 23 is twisted so that when the ring gear 23 rotates in a direction in which the oil is scooped up toward the main guide 32 (i.e., the forward direction of the vehicle), the oil is sent toward the inner surface of the first case 3A and the guide portion 33 provided on the inner surface.

[0034] In other words, the ring gear 23 is twisted so that when the ring gear 23 rotates in a direction that scoops up the oil toward the main guide 32, the oil is sent along the axial direction of the ring gear 23 toward the first differential case bearing 29A.

[0035] <Differential case> The differential case 24 is fixed to the ring gear 23 and rotates together with the ring gear 23 about a rotation axis L3 of the ring gear 23. As shown in FIG. 3 , the differential case 24 has a differential mechanism accommodating portion 241, a flange portion 242, a first shaft portion 243, a second shaft portion 244, and a window 245.

[0036] The differential mechanism accommodating portion 241 accommodates the differential mechanism 25. The flange portion 242 protrudes radially outward from the differential mechanism accommodating portion 241. The ring gear 23 is fixed to the flange portion 242.

[0037] The first shaft portion 243 is a cylindrical portion through which a first output shaft (not shown) connected to the differential mechanism 25 is inserted. The second shaft portion 244 is a cylindrical portion through which a second output shaft (not shown) connected to the differential mechanism 25 is inserted. The window 245 is an opening that communicates between the inside of the differential mechanism accommodating portion 241 and the outside of the differential mechanism accommodating portion 241.

[0038] <Differential mechanism> The differential mechanism 25 is a known mechanism that distributes and transmits the rotation of the differential case 24 to the first output shaft and the second output shaft while causing the first output shaft and the second output shaft to rotate differentially. The differential mechanism 25 is disposed inside the differential mechanism accommodating portion 241.

[0039] The differential mechanism 25 has two side gears respectively connected to the first output shaft and the second output shaft, and two pinion gears that transmit the rotation of the differential case 24 to the two side gears.

[0040] The rotational axes of the first output shaft and the second output shaft coincide with the rotational axis of the ring gear 23. The first output shaft and the second output shaft rotate differentially and in accordance with the rotational direction of the input gear 21 (i.e., the rotational direction of the differential case 24).

[0041] <Input gear bearing> The first input gear bearing 27A and the second input gear bearing 27B shown in FIG. 2 are ball bearings that support the input gear 21 rotatably.

[0042] The second input gear bearing 27B is disposed on the opposite side of the teeth of the input gear 21 from the first input gear bearing 27A in the axial direction of the input gear 21. Specifically, the first input gear bearing 27A supports the right end of the shaft portion of the input gear 21, and the second input gear bearing 27B supports the left end of the shaft portion of the input gear 21.

[0043] The first input gear bearing 27A is attached to the first case 3A, and the second input gear bearing 27B is attached to the second case 3B.

[0044] <Counter gear bearing> The first counter gear bearing 28A and the second counter gear bearing 28B are ball bearings that support the counter gear 22 rotatably.

[0045] The second counter gear bearing 28B is disposed on the opposite side of the first counter gear bearing 28A with respect to the first gear 221 and the second gear 222 in the axial direction of the counter gear 22. Specifically, the first counter gear bearing 28A supports the right end of the shaft portion of the counter gear 22, and the second counter gear bearing 28B supports the left end of the shaft portion of the counter gear 22.

[0046] The first counter gear bearing 28A is attached to the first case 3A, and the second counter gear bearing 28B is attached to the second case 3B.

[0047] <Differential case bearing> The first differential case bearing 29A and the second differential case bearing 29B are tapered roller bearings that support the differential case 24 rotatably.

[0048] The second differential case bearing 29B is disposed on the opposite side of the ring gear 23 from the first differential case bearing 29A in the axial direction of the ring gear 23. Specifically, the first differential case bearing 29A supports the first shaft portion 243 of the differential case 24, and the second differential case bearing 29B supports the second shaft portion 244 of the differential case 24.

[0049] The first differential case bearing 29A is attached to the first case 3A, and the second differential case bearing 29B is attached to the second case 3B.

[0050] <Gear case> The gear case 3 houses the power transmission mechanism 2. The gear case 3 has a first case 3A and a second case 3B that sandwich the power transmission mechanism 2 in the axial direction of the input gear 21 (that is, the left-right direction).

[0051] The first case 3A and the second case 3B are connected to each other with a number of bolts to form a storage space that contains the transmission mechanism 2, the parking lock mechanism 5, and oil. Note that in Fig. 2, the portion of the first case 3A that houses the motor (not shown), which is the drive source, is not shown.

[0052] 1, of the joint surface of the outer frame of the first case 3A with the second case 3B, the first upper central portion 3C and the first lower central portion 3D have a width (i.e., thickness in the vertical direction) greater than other regions. The first upper central portion 3C is an area that overlaps from above with part of the input gear 21, the entire counter gear 22, and part of the ring gear 23. The first lower central portion 3D is an area that overlaps from below with part of the input gear 21, the entire counter gear 22, and part of the ring gear 23.

[0053] As shown in Figure 4, among the joint surfaces of the outer frame of the second case 3B with the first case 3A, the second upper central portion 3E and the second lower central portion 3F, which are joined to the first upper central portion 3C and the first lower central portion 3D of the first case 3A, respectively, are made wider than the other areas, similar to the first upper central portion 3C and the first lower central portion 3D.

[0054] By increasing the width of the joint surface in the center of the gear case 3 in this manner, it is possible to prevent the gear case 3 from becoming larger, while also preventing oil from leaking outside the gear case 3 when the gear case 3 is deformed by load.

[0055] As shown in Figures 5 and 6, the gear case 3 has a catch tank 31, a main guide 32, a guide section 33, a hanging wall 34, a buffer section 35, a lower guide 36, a reverse guide 37, a reverse hanging wall 38, a first input gear bearing accommodating section 41A, a second input gear bearing accommodating section 41B, a first counter gear bearing accommodating section 42A, a second counter gear bearing accommodating section 42B, a first differential case bearing accommodating section 43A, a second differential case bearing accommodating section 43B, a right-side first counter gear flow path 45A, a left-side first counter gear flow path 45B, a second counter gear flow path 46, and a differential case flow path 47.

[0056] <Catch tank> Catch tank 31 is a portion that stores oil scooped up by ring gear 23. Catch tank 31 is composed of a rib that protrudes from the inner surface of first case 3A toward second case 3B (i.e., to the left) and a rib that protrudes from the inner surface of second case 3B toward first case 3A (i.e., to the right).

[0057] 1, the catch tank 31 is disposed in front of the counter gear 22 and at a position higher than the input gear 21. Moreover, as shown in FIG. 7, the catch tank 31 is disposed at a position overlapping the input gear 21 from above. The catch tank 31 has a bottom wall 311 and a side wall 312.

[0058] The bottom wall 311 is disposed across the first case 3A and the second case 3B. The bottom wall 311 has a first communication hole 311A ​​and a second communication hole 311B. The first communication hole 311A ​​communicates between the interior of the catch tank 31 and the first input gear bearing accommodating portion 41A. The first communication hole 311A ​​sends oil in the catch tank 31 to the first input gear bearing 27A by gravity.

[0059] The second communication hole 311B is provided to the left of the first communication hole 311A ​​and communicates between the interior of the catch tank 31 and the second input gear bearing accommodating portion 41B. The second communication hole 311B sends oil in the catch tank 31 to the second input gear bearing 27B by gravity.

[0060] The side wall 312 surrounds the bottom wall 311 on all four sides. The side wall 312 has an outflow portion 312A and a third communication hole 312B. The outflow portion 312A is a portion of the side wall 312 that is lower in height than other portions. The outflow portion 312A is the lowest portion of the side wall 312, and is provided in the right region of the rear wall of the side wall 312.

[0061] The outflow portion 312A is formed by a part of the rib of the first case 3A, and is provided at a position overlapping the main guide 32 from below. When the liquid level of the oil stored in the catch tank 31 exceeds the height of the outflow portion 312A, the oil flows out of the catch tank 31 from the outflow portion 312A to the outside of the catch tank 31 (specifically, to the right-side first counter gear flow path 45A). The oil flows out of the outflow portion 312A in a rearward direction.

[0062] The third communication hole 312B is provided in a left region of the rear wall of the side wall 312. The third communication hole 312B sends oil in the catch tank 31 to the first left counter gear flow path 45B (see FIG. 6).

[0063] <Main Guide> The main guide 32 sends the oil scooped up by the ring gear 23 when the ring gear 23 rotates in the forward direction of the vehicle (hereinafter also referred to as the "first direction") to the catch tank 31. The main guide 32 is composed of ribs that protrude in the axial direction of the input gear 21 from the inner surface of the first case 3A.

[0064] 8, at least a portion of the main guide 32 overlaps with the first gear 221 when viewed from the axial direction of the counter gear 22. Specifically, the central portion of the main guide 32 in the oil flow direction is disposed to the right of the first gear 221.

[0065] Furthermore, at least a portion of the main guide 32 overlaps with the second gear 222 when viewed from the radial direction of the counter gear 22. Specifically, the central portion of the main guide 32 in the oil flow direction overlaps with the second gear 222 from above.

[0066] Furthermore, the main guide 32 is disposed at a higher position than the first counter gear bearing 28A when viewed in the axial direction of the counter gear 22. In other words, the main guide 32 extends so as to straddle the first counter gear bearing 28A in the front-rear direction.

[0067] 5, the main guide 32 has an upstream end 321, a downstream end 322, and a guide surface 323. The upstream end 321 and the downstream end 322 are each end in the oil flow direction. The upstream end 321 is located at a position rearward and higher than the downstream end 322. Therefore, the main guide 32 forms a flow path through which oil flows from the upper rear to the lower front.

[0068] 1, the upstream end 321 is located radially outward from the ring gear 23. The upstream end 321 is located higher than the ring gear 23 and lower than the uppermost point P1 of the ring gear 23 and the uppermost point P2 of the first gear 221. Furthermore, the upstream end 321 is located parallel to the axial direction of the ring gear 23 and lower than an imaginary plane S that includes the uppermost point P1 of the ring gear 23 and the uppermost point P2 of the first gear 221.

[0069] The downstream end 322 is disposed above the catch tank 31. The downstream end 322 is also disposed forward of the outflow portion 312A of the catch tank 31.

[0070] The guide surface 323 is a surface along which oil flows toward the catch tank 31. The guide surface 323 forms the upper surface of the main guide 32. As shown in Fig. 8, the guide surface 323 is inclined with respect to the axial direction of the counter gear 22 so that its position decreases toward the left. This inclination is due to the draft angle of the mold for the first case 3A.

[0071] 9, the guide surface 323 has a groove 323A and a step 323B. The groove 323A is recessed downward and extends along the axial direction of the ring gear 23. Specifically, the groove 323A extends from the inner surface of the first case 3A to the buffer portion 35. The groove 323A is disposed between the upstream end 321 of the main guide 32 and the step 323B.

[0072] Step 323B is provided on the downstream side of groove 323A. Oil overflowing from groove 323A falls over step 323B and flows toward downstream end 322. Some of the oil that reaches upstream end 321 flows to the left (i.e., toward buffer portion 35) as shown by the arrow in FIG. 9, and the rest flows over groove 323A toward downstream end 322.

[0073] <Guidance part> The guide portion 33 is disposed offset from the main guide 32 in the axial direction of the ring gear 23 (that is, in the left-right direction), and guides oil to the main guide 32.

[0074] The guide portion 33 is a recessed portion provided on the inner surface of the first case 3A. The guide portion 33 is provided to the right of the main guide 32 and is recessed toward the right. The guide portion 33 extends in the front-to-rear direction and guides oil forward. The guide portion 33 forms an oil flow path that continues to the groove 323A of the main guide 32.

[0075] 5, the guide portion 33 extends from a first end 331 to a second end 332. The first end 331 is the front end of the guide portion 33. The first end 331 is connected to the upstream end 321 of the main guide 32 from above.

[0076] The second end 332 is the rear end of the guide portion 33. The second end 332 is disposed at a position overlapping with the ring gear 23 when viewed from the axial direction of the ring gear 23. Specifically, when viewed from the axial direction of the ring gear 23, the second end 332 overlaps with a portion A1 (see FIG. 1 ) just before reaching the highest point P1 of the ring gear 23 when the ring gear 23 rotates in the first direction, or with the highest point P1 of the ring gear 23. The portion A1 is a region of the outer circumferential surface of the ring gear 23 where the rotation angle θ from the highest point P1 is 10° or less.

[0077] <Drooping wall> 3, the hanging wall 34 extends downward from the second end 332 of the guide portion 33 toward the window 245 of the differential case 24. The hanging wall 34 is formed of a rib protruding from the inner surface of the first case 3A.

[0078] 5, the hanging wall 34 has a first surface 341 and a second surface 342 that extend in the vertical direction. The first surface 341 faces rearward, and the second surface 342 faces forward. Oil that reaches a position lower than the second end 332 of the guide portion 33 is guided to the window 245 by the first surface 341.

[0079] <Buffer section> 9 sends a portion of the oil flowing through the main guide 32 to the second differential case bearing 29B. The buffer portion 35 is composed of a rib that protrudes in the axial direction of the input gear 21 from the inner surface of the second case 3B.

[0080] The buffer portion 35 has a bottom wall 351 and a side wall 352. The bottom wall 351 is connected to the groove 323A of the main guide 32 in the axial direction of the ring gear 23. That is, oil is supplied to the buffer portion 35 from the groove 323A.

[0081] The side wall 352 surrounds the bottom wall 351 from the front, rear, and left. The side wall 352 has an outflow section 352A. The outflow section 352A is a section of the side wall 352 that is lower in height than other sections. The outflow section 352A is the lowest section of the side wall 352, and is provided on the rear wall of the side wall 352.

[0082] The outflow portion 352A is provided on the left side of the upstream end 321 of the main guide 32, and allows the oil in the buffer portion 35 to flow toward the second differential case bearing 29B. The height of the highest point of the outflow portion 352A is equal to or lower than the height of the highest point of the groove 323A of the main guide 32.

[0083] When the liquid level of the oil stored in the buffer 35 exceeds the height of the outflow portion 352A, the oil flows out of the buffer 35 from the outflow portion 352A to the outside of the buffer 35. The oil flows out of the outflow portion 352A backward. In other words, the oil flows out of the buffer 35 in the opposite direction to the oil flow in the main guide 32.

[0084] <Lower guide> The lower guide 36 shown in Figure 4 faces the ring gear 23 from the radial outside at a position lower than the rotational axis L3 of the ring gear 23, and also faces the first gear 221 from the radial outside at a position lower than the rotational axis L2 of the first gear 221.

[0085] The lower guide 36 is composed of a rib (see Figure 1) that protrudes from the inner surface of the first case 3A toward the second case 3B (i.e., to the left), and a rib that protrudes from the inner surface of the second case 3B toward the first case 3A (i.e., to the right).

[0086] Specifically, the lower guide 36 has a rear portion 361 extending along the outer edge of the ring gear 23, and a front portion 362 extending forward from the front end of the rear portion 361. The rear portion 361 faces the front lower portion of the ring gear 23. The front portion 362 faces the lower portion of the first gear 221. The front portion 362 reaches the first input gear bearing receiving portion 41A and the second input gear bearing receiving portion 41B.

[0087] The oil scooped up when ring gear 23 rotates in the reverse direction of the vehicle (hereinafter also referred to as the "second direction") is sent to front portion 362. The oil sent to front portion 362 is further scooped up by first gear 221.

[0088] 5 and 6, the lower guide 36 divides the internal space of the gear case 3 (i.e., the oil storage space) into a front portion 3G and a rear portion 3H. The lower end (i.e., the rear end) of the lower guide 36 is spaced apart from the lower surface of the internal space of the gear case 3. The gap between the lower end of the lower guide 36 and the lower surface of the internal space of the gear case 3 forms a flow path for oil from the front portion 3G to the rear portion 3H.

[0089] By dividing the oil storage space with the lower guide 36 in this way, the amount of oil in which the ring gear 23 is immersed while the automobile is running is reduced, and the stirring resistance of the ring gear 23 is therefore reduced.

[0090] <Reverse Guide> 6 sends the oil that has been scooped up by the ring gear 23 and then further scooped up by the first gear 221 in the lower guide 36 to the catch tank 31 when the ring gear 23 rotates in the second direction. The reverse guide 37 is made up of ribs that protrude from the inner surface of the second case 3B in the axial direction of the input gear 21.

[0091] 10, the reverse guide 37 is disposed at a position overlapping with the first gear 221 in the axial direction of the counter gear 22. Specifically, the upstream portion of the reverse guide 37 in the oil flow direction is disposed on the left side of the first gear 221.

[0092] The reverse guide 37 has an upstream end 371, a downstream end 372, and a guide surface 373. The upstream end 371 and the downstream end 372 are each end in the oil flow direction. As shown in FIG. 6, the upstream end 371 is located rearward and higher than the downstream end 372. Therefore, the reverse guide 37 forms a flow path through which oil flows from the upper rear to the lower front. The upstream end 371 is located higher than the second counter gear bearing housing portion 42B and forward of the rotation axis L2 of the counter gear 22.

[0093] The downstream end 372 is disposed above the catch tank 31. The downstream end 372 is connected to the rear wall of the side walls 312 of the catch tank 31.

[0094] Guide surface 373 is a surface along which oil flows toward catch tank 31. Guide surface 373 forms the upper surface of reverse guide 37. As shown in FIG. 10 , guide surface 373 has a width perpendicular to the oil flow direction (i.e., width in the left-right direction) that increases toward catch tank 31.

[0095] <Reverse hanging wall> The reverse hanging wall 38 shown in FIG. 6 supplies the oil scooped up by the ring gear 23 when the ring gear 23 rotates in the second direction to the second differential case bearing 29B.

[0096] The reverse hanging wall 38 is configured as a part of a recess (specifically, the rear wall) provided on the inner surface of the second case 3B. The reverse hanging wall 38 has a wall surface facing forward. The reverse hanging wall 38 is disposed rearward of the buffer portion 35 and above the second differential case bearing housing portion 43B.

[0097] <Bearing housing> The first input gear bearing accommodating portion 41A, the first counter gear bearing accommodating portion 42A, and the first differential case bearing accommodating portion 43A shown in Figure 5 accommodate the first input gear bearing 27A, the first counter gear bearing 28A, and the first differential case bearing 29A, respectively.

[0098] The first input gear bearing accommodating portion 41A, the first counter gear bearing accommodating portion 42A, and the first differential case bearing accommodating portion 43A are recesses provided on the inner surface of the first case 3A. The first input gear bearing accommodating portion 41A has an opening through which the motor shaft is inserted. The first differential case bearing accommodating portion 43A has an opening through which the first output shaft is inserted. Oil seals are arranged in these openings.

[0099] The second input gear bearing accommodating portion 41B, the second counter gear bearing accommodating portion 42B, and the second differential case bearing accommodating portion 43B shown in Figure 6 accommodate the second input gear bearing 27B, the second counter gear bearing 28B, and the second differential case bearing 29B, respectively.

[0100] The second input gear bearing accommodating portion 41B, the second counter gear bearing accommodating portion 42B, and the second differential case bearing accommodating portion 43B are recesses provided on the inner surface of the second case 3B. The second differential case bearing accommodating portion 43B has an opening through which the second output shaft is inserted. An oil seal is disposed in this opening.

[0101] <First counter gear passage> 5 sends the oil flowing out from the outlet 312A of the catch tank 31 to the first counter gear bearing 28A. The right first counter gear flow path 45A flows the oil rearward toward the first counter gear bearing 28A.

[0102] The right-side first counter gear flow path 45A is formed by recesses and ribs provided on the inner surface of the first case 3A. The right-side first counter gear flow path 45A extends from the outlet portion 312A of the catch tank 31 to the first counter gear bearing accommodating portion 42A.

[0103] 6 sends oil from the catch tank 31 to the second counter gear bearing 28B. The left first counter gear flow path 45B flows oil rearward toward the second counter gear bearing 28B.

[0104] The left first counter gear flow path 45B is a communication hole provided in the second case 3B. The left first counter gear flow path 45B is a communication hole that communicates between the third communication hole 312B of the catch tank 31 and the second counter gear bearing accommodating portion 42B.

[0105] <Second counter gear passage> 5 sends the oil scooped up by the ring gear 23 directly to the first counter gear bearing 28A. The second counter gear flow path 46 flows the oil forward toward the first counter gear bearing 28A. The second counter gear flow path 46 is formed by a rib protruding from the inner surface of the first case 3A.

[0106] The second counter gear flow path 46 is disposed at a position lower than the upstream end 321 of the main guide 32. Specifically, the entire second counter gear flow path 46 is disposed below the main guide 32. When viewed in the axial direction of the ring gear 23, at least a portion of the second counter gear flow path 46 overlaps with the ring gear 23. The second counter gear flow path 46 extends from a region below and forward of the upstream end 321 of the main guide 32 to the first counter gear bearing accommodating portion 42A.

[0107] <Differential case flow passage> The differential case flow path 47 sends oil from the first counter gear bearing 28A to the first differential case bearing 29A. The differential case flow path 47 is a communication hole provided in the first case 3A.

[0108] The differential case flow path 47 is disposed below the second counter gear flow path 46. The differential case flow path 47 communicates between the first counter gear bearing receiving portion 42A and the first differential case bearing receiving portion 43A.

[0109] <Parking lock mechanism> The parking lock mechanism 5 shown in FIG. 1 is capable of being switched between a locked state in which the rotation of the input gear 21 is restricted and a released state in which the rotation is permitted.

[0110] <Oil behavior> As shown by the arrow in Figure 5, when the vehicle is moving forward (i.e., when the ring gear 23 rotates in the first direction D1), the oil O stored in the rear part 3H of the gear case 3 is scooped up by the ring gear 23 toward the main guide 32.

[0111] The oil O scooped up by the ring gear 23 reaches the main guide 32 and is sent to the catch tank 31 by the main guide 32. In addition, due to the twisting of the ring gear 23, a portion of the oil O is sent to the guide section 33. The oil O sent to the guide section 33 is sent to the main guide 32. The oil O sent to the hanging wall 34 is guided by the hanging wall 34 and supplied to the window 245 of the differential case 24.

[0112] The oil O sent to the catch tank 31 is supplied to the first input gear bearing 27A and the oil seal of the first input gear bearing accommodating portion 41A through a first communication hole 311A ​​provided in the bottom wall 311. In addition, the oil O overflowing from the outflow portion 312A of the catch tank 31 is supplied to the first counter gear bearing 28A through the right-side first counter gear flow path 45A.

[0113] Furthermore, some of the oil scooped up by the ring gear 23 is supplied to the first counter gear bearing 28A by the second counter gear flow path 46 without passing through the catch tank 31. When the rotational speed of the ring gear 23 is low, the amount of oil O scooped up by the ring gear 23 that reaches the main guide 32 decreases, and the amount that reaches the second counter gear flow path 46 increases.

[0114] The oil supplied to the first counter gear bearing 28A is supplied to the first differential case bearing 29A, the oil seal of the first differential case bearing housing portion 43A, and the sliding portion between the first shaft portion 243 and the first main shaft by the differential case flow path 47. The oil O supplied to the first differential case bearing 29A is returned to the rear portion 3H of the gear case 3.

[0115] 6, when the vehicle is moving forward, on the second case 3B side, oil O sent to the catch tank 31 is supplied to the second input gear bearing 27B from the second communication hole 311B provided in the bottom wall 311. In addition, oil O in the catch tank 31 is supplied to the second counter gear bearing 28B from the third communication hole 312B via the left first counter gear flow path 45B.

[0116] Furthermore, a portion of the oil O scooped up into the main guide 32 by the ring gear 23 is supplied to the buffer portion 35 through the groove 323A of the main guide 32. The oil O that overflows from the outflow portion 352A of the buffer portion 35 is supplied to the second differential case bearing 29B, the oil seal of the second differential case bearing housing portion 43B, and the sliding portion between the second shaft portion 244 and the second main shaft. Note that no oil flows into the reverse guide 37 when the vehicle is moving forward.

[0117] 11, when the vehicle is moving backward (i.e., when the ring gear 23 rotates in the second direction D2), the oil O accumulated in the rear portion 3H of the gear case 3 is scooped up toward the front along the lower guide 36 by the ring gear 23. The oil O scooped up onto the lower guide 36 by the ring gear 23 is then scooped up toward the reverse guide 37 by the first gear 221.

[0118] The oil O scooped up by the first gear 221 reaches the reverse guide 37 and is sent to the catch tank 31 by the reverse guide 37. Some of the oil O scooped up by the first gear 221 splashes and reaches the reverse hanging wall 38, and is supplied along the wall surface of the reverse hanging wall 38 to the second differential case bearing 29B, the oil seal of the second differential case bearing housing portion 43B, and the sliding portion between the second shaft portion 244 and the second main power shaft.

[0119] As shown by the arrows in FIG. 12, on the first case 3A side, some of the oil O scooped up by the ring gear 23 splashes and reaches the second surface 342 of the hanging wall 34, and is supplied to the window 245 of the differential case 24.

[0120] When the vehicle is moving backward, the oil O sent to the catch tank 31 is supplied to each bearing and oil seal through the same flow path as when the vehicle is moving forward. When the vehicle is moving backward, no oil flows through the main guide 32.

[0121] [1-2.Effects] According to the embodiment described above in detail, the following effects can be obtained. (1a) When the ring gear 23 rotates in the second direction, oil is sent to the reverse guide 37 due to the upward movement of the first gear 221 and the twisting of the first gear 221. As a result, the oil is supplied to the catch tank 31 via the reverse guide 37. Therefore, it is possible to suppress a decrease in the lubricity of the bearing when the rotational speed of the ring gear 23 in the second direction is low (i.e., when the vehicle is moving backward).

[0122] (1b) The reverse guide 37 is a rib that protrudes from the inner surface of the second case 3B, which reduces the cost of forming the reverse guide 37. In addition, the width of the guide surface 373 increases toward the catch tank 31, which allows the oil that is sent toward the inner surface of the second case 3B due to the twisting of the first gear 221 to be efficiently sent to the catch tank 31.

[0123] (1c) By arranging the upstream end 371 of the reverse guide 37 at a position higher than the downstream end 372, oil that has reached the reverse guide 37 can easily flow toward the catch tank 31.

[0124] 2. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0125] (2a) In the transmission device of the above embodiment, the gear case does not necessarily have to have a first case and a second case. In other words, the gear case does not necessarily have to be composed of parts separated in the axial direction of the input gear.

[0126] (2b) In the transmission device of the above embodiment, the guide surface of the reverse guide does not necessarily have to increase in width toward the catch tank. Also, the upstream end of the reverse guide does not necessarily have to be positioned higher than the downstream end.

[0127] (2d) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical idea identified by the wording of the claims are embodiments of the present disclosure.

Claims

1. A transmission mechanism; a gear case that houses the transmission mechanism; Equipped with The transmission mechanism includes: An input gear; a counter gear having a rotation axis parallel to the rotation axis of the input gear; a ring gear having a rotation axis parallel to the rotation axis of the input gear; a differential case fixed to the ring gear; A differential mechanism disposed inside the differential case; an input gear bearing that rotatably supports the input gear; a counter gear bearing that rotatably supports the counter gear; A differential case bearing that rotatably supports the differential case; and The counter gear is a first gear that meshes with the input gear; a second gear having an outer diameter smaller than that of the first gear, arranged concentrically with the first gear, and meshing with the ring gear; and a rotation axis of the counter gear is located above a rotation axis of the input gear and a rotation axis of the ring gear, The gear case includes: a lower guide facing the ring gear from a radially outer side at a position lower than the rotation axis of the ring gear and facing the first gear from a radially outer side at a position lower than the rotation axis of the first gear; a catch tank disposed at a position overlapping the input gear from above; a main guide that sends oil scooped up by the ring gear to the catch tank when the ring gear rotates in a first direction; a reverse guide that sends the oil scooped up by the ring gear and then scooped up by the first gear to the catch tank when the ring gear rotates in a second direction opposite to the first direction; and the reverse guide is disposed at a position overlapping with the first gear in the axial direction of the counter gear, the first gear is a helical gear twisted such that the oil is directed toward the reverse guide when the first gear rotates in the second direction.

2. 2. The transmission device according to claim 1, the gear case includes a first case and a second case that sandwich the transmission mechanism in the axial direction of the input gear, the reverse guide is a rib that protrudes from the inner surface of the second case in the axial direction of the input gear and has a guide surface along which the oil flows toward the catch tank, The guide surface has a width perpendicular to the oil flow direction that increases toward the catch tank.

3. The transmission device according to claim 1 or 2, the reverse guide has an upstream end and a downstream end in the oil flow direction, The upstream end is positioned higher than the downstream end.

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