Power transmission device

Abstract

To provide a power transmission device capable of increasing a quantity of oil which can be stored in a catch tank.SOLUTION: A case 81 has a first storage space 81A which stores a ring gear 61 of a differential 60 and a ring gear 42 of a planetary gear mechanism 40. The case 81 has a first catch tank 150 and a second catch tank 160 capable of storing oil as a part of the first storage space 81A. The first catch tank 150 is located on an upper side when viewed from a rotation axial line of the ring gear 61 of the differential 60, and on the upper side when viewed from a rotation axial line of the ring gear 42 of the planetary gear mechanism 40. A second catch tank 160 is located on the upper side when viewed from the rotation axial line of the ring gear 61 of the differential 60, is located on the upper side when viewed a rotation axial line of the ring gear 42 of the planetary gear mechanism 40 and, on a lower direction when viewed from a front end of the first catch tank 150.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This invention relates to a power transmission device.

Background Art

[0002] The power transmission device disclosed in Patent Document 1 includes a case, a gear mechanism, and a differential. The case houses the gear mechanism and the differential. The gear mechanism has a plurality of gears. The gear mechanism transmits the power from the vehicle's drive source to the differential via the plurality of gears. The differential has a ring gear and a differential mechanism. The ring gear meshes with the gears of the gear mechanism. The differential mechanism transmits the power input via the ring gear to the left and right drive wheels of the vehicle. At that time, the differential mechanism allows a difference in rotational speed to occur between the left and right drive wheels.

[0003] The case can store oil at its bottom. Also, the case has a catch tank. The catch tank is located on the upper side when viewed from one of the plurality of gears in the gear mechanism. The catch tank stores the oil lifted up by the rotation of the gears of the gear mechanism and the ring gear of the differential.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the case of a case having a catch tank as in Patent Document 1, depending on the structure of the case, there may not be enough space to install the catch tank. In this case, the capacity of the oil that can be stored in the catch tank decreases. When the capacity of the catch tank is small in this way, the oil at the bottom of the case increases, so there is a risk that the stirring resistance of each gear will increase.

Means for Solving the Problems

[0006] The power transmission device for solving the above problems includes a gear mechanism that transmits power from a drive source of a vehicle, a differential that allows a difference in rotational speed to occur between the left and right drive wheels of the vehicle when power is transmitted from the gear mechanism, and a case that houses the gear mechanism and the differential. The differential has a ring gear to which power from the gear mechanism is transmitted. When the rotation axis of the ring gear is defined as the first rotation axis, the gear mechanism has a specific gear that rotates about a second rotation axis parallel to the first rotation axis. The case has an accommodation space that houses the ring gear and the specific gear. The case includes a first catch tank and a second catch tank that can store oil as part of the accommodation space. When a specific direction among the directions orthogonal to the first rotation axis is defined as the upward direction, the first catch tank is located on the upward side when viewed from the first rotation axis and also on the upward side when viewed from the second rotation axis. When the direction opposite to the upward direction is defined as the downward direction and the direction orthogonal to both the first rotation axis and the upward direction is defined as the lateral direction, the second catch tank is located on the upward side when viewed from the first rotation axis, also on the upward side when viewed from the second rotation axis, and on the downward side when viewed from the lateral end of the first catch tank.

[0007] In the above configuration, assume that the power transmission device is mounted on the vehicle so that the upward direction of the power transmission device coincides with the upward direction of the vehicle. In this case, the oil that overflows from the lateral end of the first catch tank can be received by the second catch tank. Therefore, more oil can be stored than in the case of the first catch tank alone.

[0008] In the power transmission device, the case has a first main wall and a second main wall facing each other, a peripheral wall extending parallel to the first rotation axis and partitioning the accommodation space together with the first main wall and the second main wall, and a partition wall extending parallel to the first rotation axis and partitioning the first catch tank and the second catch tank. The partition wall is located between the specific gear and the peripheral wall, and has a bottom wall extending in an arc shape centered on the second rotation axis, a first side wall extending upward from the bottom wall, a second side wall extending upward from the bottom wall and separated from the first side wall, and a third side wall extending upward from the bottom wall and located on the opposite side of the first side wall with the second side wall interposed therebetween. The first catch tank is partitioned by the bottom wall, the first side wall, and the second side wall, and the second catch tank may be partitioned by the bottom wall, the second side wall, and the third side wall.

[0009] According to the above configuration, the first catch tank and the second catch tank can be partitioned along the outer edge of the specific gear. In this way, by utilizing the space between the specific gear and the peripheral wall and arranging each catch tank in an arc shape in the space, even when the free space in the case is narrow, a large volume of the catch tank can be ensured.

[0010] In the power transmission device, the upper end of the third side wall may be located on the lower side when viewed from the upper end of the second side wall. According to the above configuration, when the case is inclined such that the third side wall is located more downward when viewed from the second side wall, the oil stored in the second catch tank can easily cross the third side wall. Thereby, the oil can be appropriately dropped to the bottom of the case.

[0011] In the power transmission device, the bottom wall may exist in a range of 75 degrees or more centered on the second rotation axis in a plan view from the direction along the second rotation axis. When arranging a catch tank in the outer peripheral space of a specific gear, the bottom wall can be extended within a range of 75 degrees or more as in the above configuration. In this way, by correspondingly increasing the arc length of the bottom wall, a larger volume of the catch tank can be ensured. Moreover, since the shape of the bottom wall is arc-shaped, the rigidity of the bottom wall can be ensured even when ensuring an appropriate length as in the above configuration.

[0012] In the power transmission device, the case may include a first piece having the first main wall, a second piece having the second main wall, bolts for fixing the first piece and the second piece in a joined state to each other, and a guard extending from the first main wall or the second main wall and located on the upward side when viewed from the first catch tank.

[0013] In the above configuration, for example, a part of the oil wound up by the ring gear hits the guard before hitting the peripheral wall. Therefore, it is possible to suppress the oil from colliding forcefully with the joint surface between the first piece and the second piece. As a result, it is possible to prevent the oil from oozing out from the joint surface between the first piece and the second piece.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] The following describes an embodiment of a power transmission device applied to a vehicle with reference to the drawings. In this embodiment, it is assumed that the up-down, front-back, and left-right directions of the power transmission device coincide with those of the vehicle. And in this embodiment, the configuration of the power transmission device will be described based on the up-down, front-back, and left-right directions of the vehicle. Also, hereinafter, for example, the upper side is simply referred to as the upper side. Here, the upper side viewed from a certain position refers to not only the vertical axis passing through that position but also all regions above that position including the front-back, left, and right directions. Although the upper direction has been described as an example here, the same applies to other directions.

[0016] <Overall Configuration of the Vehicle> As shown in FIG. 1, the vehicle 500 has an internal combustion engine 99, a transmission 80, two drive shafts 96, and two drive wheels 97. The internal combustion engine 99 is a drive source of the vehicle 500. The internal combustion engine 99 has a crankshaft 99A as an output shaft. The crankshaft 99A is connected to the transmission 80. Kusu The transmission 80 is a power transmission device. The transmission 80 is connected to the drive wheels 97 via the drive shafts 96. Kusu The transmission 80 is connected to the transmission 80. Kusu The transmission 80 is a power transmission device. The transmission 80 is connected to the drive wheels 97 via the drive shafts 96. Kusu The transmission 80 is connected to the drive wheels 97 via the drive shafts 96.

[0017] The transmission 80 is Kusu has a case 81, a planetary gear mechanism 40, a reduction mechanism 50, a differential 60, a first motor generator (hereinafter referred to as the first MG) 71, and a second motor generator (hereinafter referred to as the second MG) 72.

[0018] The case 81 houses the planetary gear mechanism 40, the reduction mechanism 50, the differential 60, the first MG 71, and the second MG 72. The detailed structure of the case 81 will be described in detail. The first MG71 is a drive source of the vehicle 500. The first MG71 has the functions of both an electric motor and a generator. The first MG71 has a main body 71P and a rotating shaft 71A. The main body 71P includes a rotor and a stator. The rotating shaft 71A is a power input / output shaft with respect to the main body 71P and rotates integrally with the rotor of the main body 71P. The rotation center axis of the rotating shaft 71A extends left and right of the vehicle 500. In the following description, the rotation center axis is simply referred to as the rotation axis.

[0019] The second MG72 is, like the first MG71, a drive source of the vehicle 500 and has the functions of both an electric motor and a generator. In addition to a main body 72P and a rotating shaft 72A similar to those of the first MG71, the second MG72 has a connection gear 72B. The shape of the connection gear 72B is generally disk-shaped. The connection gear 72B has external teeth. The connection gear 72B is connected to the rotating shaft 72A. The connection gear 72B rotates integrally with the rotating shaft 72A. The rotation axis 72Z of the rotating shaft 72A and the connection gear 72B is substantially parallel to the rotation axis of the rotating shaft 71A of the first MG71.

[0020] The planetary gear mechanism 40 has a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The shape of the sun gear 41 is generally disk-shaped. The sun gear 41 has external teeth. The sun gear 41 is connected to the rotation axis 71A of the first MG 71. The shape of the ring gear 42 is generally annular. The ring gear 42 has internal teeth and external teeth. The ring gear 42 is positioned coaxially with the sun gear 41. The rotation axis 42Z of the ring gear 42 substantially coincides with the rotation axes of the sun gear 41 and the rotation axis 71A of the first MG 71. Each pinion gear 43 is positioned between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the external teeth of the sun gear 41 and the internal teeth of the ring gear 42. The carrier 44 supports the pinion gears 43 so as to be rotatable about their own axes and revolvable. The carrier 44 is connected to the crankshaft 99A. Note that the external teeth of the ring gear 42 are connected to the speed reduction mechanism 50. Then, the ring gear 42 transmits the power of the first MG 71 input via the sun gear 41 and the power of the internal combustion engine 99 input via the carrier 44 to the speed reduction mechanism 50. This ring gear 42 corresponds to a specific gear.

[0021] The speed reduction mechanism 50 has a first reduction gear 51 and a second reduction gear 52. The shape of the first reduction gear 51 is generally disk-shaped. The first reduction gear 51 has external teeth. The first reduction gear 51 meshes with the external teeth of the ring gear 42 of the planetary gear mechanism 40. The first reduction gear 51 also meshes with the connection gear 72B of the second MG 72. The shape of the second reduction gear 52 is generally disk-shaped. The second reduction gear 52 has external teeth. The second reduction gear 52 is positioned coaxially with the first reduction gear 51. The second reduction gear 52 is connected to the first reduction gear 51 and rotates integrally with the first reduction gear 51. The rotation axes of the first reduction gear 51 and the second reduction gear 52 are substantially parallel to the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. Note that the outer diameter of the second reduction gear 52 is smaller than the outer diameter of the first reduction gear 51.

[0022] The differential 60 has a ring gear 61, a differential case 62, and a differential mechanism 63. The shape of the ring gear 61 is generally annular. The ring gear 61 has external teeth. The ring gear 61 meshes with the second reduction gear 52. That is, the ring gear 61 receives the power of the internal combustion engine 99 and the first MG 71 transmitted by the planetary gear mechanism 40 via the reduction mechanism 50. The rotation axis 61Z of the ring gear 61 is substantially parallel to the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40.

[0023] The differential case 62 is generally cylindrical. The differential case 62 fits on the inner peripheral surface of the ring gear 61 and rotates integrally with the ring gear 61. The differential case 62 houses the differential mechanism 63. The differential case 62 transmits the rotation of the ring gear 61 to the differential mechanism 63. The differential mechanism 63 is connected to two drive shafts 96. The drive shafts 96 are present one on each side with the differential mechanism 63 in between. The left and right drive shafts 96 penetrate the case 81 and extend to the outside of the case 81. Each drive shaft 96 is connected to a drive wheel 97 outside the case 81. The differential mechanism 63 transmits the rotation of the ring gear 61 via the differential case 62 to the left and right drive shafts 96, and thus to the left and right drive wheels 97. At this time, the differential mechanism 63 allows a difference in rotational speed to occur between the left and right drive wheels 97.

[0024] In the above-mentioned transfer Kusu In the case of 80, the rotation axis 61Z of the ring gear 61 of the differential 60 corresponds to the first rotation axis. The rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40 corresponds to the second rotation axis.

[0025] <Electrical Configuration of the Vehicle> Vehicle 500 has a battery 92 and a power control unit 91. The battery 92 is electrically connected to a first MG 71 and a second MG 72 via the power control unit 91. The battery 92 supplies power to the first MG 71 and the second MG 72, or stores the power supplied from the first MG 71 and the second MG 72. The power control unit 91 includes an inverter that performs DC-AC power conversion.

[0026] <Configuration of the case> The case 81 has a first piece 10, a second piece 20, a third piece 30, and a plurality of bolts B. The case 81 is formed by joining these three pieces together. Below, the individual structures of these pieces will be described, and then the joined state of these pieces will be described.

[0027] The first piece 10 has a first main wall 11, a first peripheral wall 12, and a first flange 13. As shown in FIG. 2, the first main wall 11 is flat. The shape of the first main wall 11 is generally triangular. The first peripheral wall 12 extends from the outer edge of the first main wall 11. The first peripheral wall 12 is substantially orthogonal to the first main wall 11. The first peripheral wall 12 is continuous over the entire outer edge of the first main wall 11. The first flange 13 projects outward from the end of the first peripheral wall 12 on the side opposite to the first main wall 11. The first flange 13 is continuous over the entire end of the first peripheral wall 12. The first flange 13 has a plurality of bolt holes 14. The plurality of bolt holes 14 are arranged at substantially equal intervals along the above-mentioned end of the first peripheral wall 12. Each bolt hole 14 penetrates the first flange 13. Note that all other bolt holes described hereinafter are also through holes.

[0028] As shown in FIG. 1, the second piece 20 has a second main wall 21, a second peripheral wall 22, a second flange 23, a third peripheral wall 25, and a third flange 26. As shown in FIG. 3, the second main wall 21 is flat. The shape of the second main wall 21 is generally triangular. The dimensions of the outer edge of the second main wall 21 are substantially the same as those of the outer edge of the first main wall 11. The second peripheral wall 22 extends from the outer edge of the second main wall 21. The second peripheral wall 22 is substantially orthogonal to the second main wall 21. The second peripheral wall 22 is continuous throughout the outer edge of the second main wall 21. The second flange 23 projects outward from the end of the second peripheral wall 22 on the side opposite to the second main wall 21. The second flange 23 is continuous over the entire circumference of the above-mentioned end of the second peripheral wall 22. The second flange 23 has a plurality of bolt holes 24. The plurality of bolt holes 24 are arranged at substantially equal intervals along the above-mentioned end of the second peripheral wall 22.

[0029] As shown in FIG. 1, the third peripheral wall 25 extends from the second main wall 21 in a direction opposite to the second peripheral wall 22. The third peripheral wall 25 is in the shape of a frame and is integrally formed. The third flange 26 projects outward from the end of the third peripheral wall 25 on the side opposite to the second main wall 21. The third flange 26 is continuous over the entire area of the above-mentioned end of the third peripheral wall 25. The third flange 26 has a plurality of bolt holes. The plurality of bolt holes are arranged at substantially equal intervals along the above-mentioned end of the third peripheral wall 25.

[0030] The third piece 30 is flat. The contour of the outer edge of the third piece 30 is substantially the same as the contour of the outer edge of the third flange 26 of the second piece 20. The third piece 30 has a plurality of bolt holes. The plurality of bolt holes are arranged at substantially equal intervals along the outer edge of the third piece 30.

[0031] The first piece 10, the second piece 20, and the third piece 30 described above are mounted on the vehicle 500 in the following joined state and arrangement. As shown in FIGS. 1 and 4, the first piece 10, the second piece 20, and the third piece 30 are arranged side by side on the left and right of the vehicle 500. The first piece 10 is located at the right end of these three pieces. The first piece 10 is arranged in an open state to the left. The first flange 13 of the first piece 10 faces the second flange 23 of the second piece 20. The positions of the opening edges of the first peripheral wall 12 of the first piece 10 and the opening edges of the second peripheral wall 22 of the second piece 20 coincide with each other. Also, all of the plurality of bolt holes 14 in the first flange 13 and the plurality of bolt holes 24 in the second flange 23 face each other. The bolt B passes through the facing bolt holes. The bolt B fixes the first piece 10 and the second piece 20 in a joined state with each other.

[0032] In a state where the first piece 10 and the second piece 20 are joined, the first main wall 11 of the first piece 10 and the second main wall 21 of the second piece 20 face each other at positions separated from each other. As shown in FIGS. 2 and 3, one of the three vertices of the triangle of the first main wall 11 and the second main wall 21 is located at the top, and the remaining two are at substantially the same positions above and below the vehicle 500.

[0033] Also, as shown in FIGS. 1 and 4, in a state where the first piece 10 and the second piece 20 are joined, the first peripheral wall 12 and the second peripheral wall 22 constitute a continuous peripheral wall 85. The peripheral wall 85 extends to the left and right of the vehicle 500. The peripheral wall 85 partitions the first accommodation space 81A together with the first main wall 11 and the second main wall 21.

[0034] As shown in FIG. 1, the third piece 30 closes the opening of the third peripheral wall 25 of the second piece 20. That is, the portion near the outer edge of the third piece 30 faces the third flange 26 of the second piece 20. All of the plurality of bolt holes in the third piece 30 and the plurality of bolt holes in the third flange 26 face each other. The bolt B penetrates through the facing bolt holes. The bolt B fixes the second piece 20 and the third piece 30 in a state where they are joined to each other. The second main wall 21, the third peripheral wall 25 of the second piece 20, and the third piece 30 define the second accommodation space 81B.

[0035] <Arrangement of Each Gear in the Accommodation Space> As shown in FIG. 1, the first accommodation space 81A accommodates the connecting gear 72B of the second MG 72, the speed reduction mechanism 50, the planetary gear mechanism 40, and the differential 60. On the other hand, the second accommodation space 81B accommodates the main body 71P of the first MG 71 and the main body 72P of the second MG 72. The rotation axes 71A of the first MG 71 and 72A of the second MG 72 penetrate through the second main wall 21 of the second piece 20.

[0036] As described above, the rotation axes of the gears such as the ring gear 42 of the planetary gear mechanism 40 and the ring gear 61 of the differential 60 extend in the left-right direction of the vehicle 500. Also, as described above, the peripheral wall 85 of the case 81 extends in the left-right direction of the vehicle 500. That is, the peripheral wall 85 of the case 81 extends substantially parallel to the rotation axes of the gears. The first main wall 11 and the second main wall 21 are substantially orthogonal to the rotation axes of the gears. Note that when the peripheral wall 85 extends parallel to the rotation axis Extension it means that it is sufficient if the peripheral wall 85 is generally along the rotation axis as a whole, and it may have portions that are not geometrically perfectly parallel.

[0037] The arrangement of each component in the first accommodation space 81A will be described in further detail. In describing the arrangement of each component, from the perspective of its relationship with the oil storage structure described later, regarding the planetary gear mechanism 40, the ring gear 42 with the largest outer diameter among its components will be the object of description. Similarly, regarding the differential 60, the ring gear 61 with the largest outer diameter among its components will be the object of description. Also, regarding the speed reduction mechanism 50, the first speed reduction gear 51 with the largest outer diameter among its components will be the object of description. Among the ring gear 42 of the planetary gear mechanism 40, the ring gear 61 of the differential 60, and the first speed reduction gear 51, the one with the largest outer diameter is the ring gear 61 of the differential 60.

[0038] As shown in FIG. 3, the ring gear 42 of the planetary gear mechanism 40, the ring gear 61 of the differential 60, and the connection gear 72B of the second MG 72 are arranged as a whole as follows. That is, when viewed in plan from the direction along the rotation axis line 42Z of the ring gear 42 of the planetary gear mechanism 40, one of the above three gears is located near each vertex of the triangle of the second main wall 21. Specifically, the ring gear 42 of the planetary gear mechanism 40 is located in the frontward portion in the first accommodation space 81A. The ring gear 61 of the differential 60 is located on the rear side when viewed from the rearmost end of the ring gear 42 of the planetary gear mechanism 40. The rotation axis line 61Z of the ring gear 61 of the differential 60 is located slightly below when viewed from the rotation axis line 42Z of the ring gear 42 of the planetary gear mechanism 40. The connection gear 72B of the second MG 72 is located on the rear side when viewed from the rearmost end of the ring gear 42 of the planetary gear mechanism 40. Further, the connection gear 72B of the second MG 72 is located above when viewed from both the uppermost end of the ring gear 42 of the planetary gear mechanism 40 and the uppermost end of the ring gear 61 of the differential 60. And the first reduction gear 51 is located between the connection gear 72B and the ring gear 42 of the planetary gear mechanism 40. As described above, the first reduction gear 51 meshes with both the connection gear 72B and the ring gear 42 of the planetary gear mechanism 40. As described above, the outer diameter of the ring gear 61 of the differential 60 is larger than the outer diameter of the ring gear 42 of the planetary gear mechanism 40. Therefore, due to the arrangement of the above-described respective gears, the lowermost end of the ring gear 61 of the differential 60 is located below when viewed from the lowermost ends of the other gears.

[0039] The ring gear 42 of the planetary gear mechanism 40 is located on the front side and the lower side when viewed from the apex located at the uppermost part of the triangle of the second main wall 21. Also, this ring gear 42 is located on the rear side and the upper side when viewed from the apex located at the foremost part of the triangle of the second main wall 21. Here, the side connecting the uppermost apex and the foremost apex of the triangle of the second main wall 21 is referred to as the specific side. And, among the peripheral wall 85 of the case 81, the portion along the above specific side is referred to as the specific portion 85A. A catch tank for storing oil is provided between this specific portion 85A and the ring gear 42 of the planetary gear mechanism 40. Hereinafter, this catch tank will be described in detail.

[0040] <Catch tank> As shown in FIG. 3, the case 81 has a first catch tank 150 and a second catch tank 160. The first catch tank 150 and the second catch tank 160 are spaces capable of storing oil. The first catch tank 150 and the second catch tank 160 are a part of the first accommodation space 81A.

[0041] The case 81 has a partition wall 103 as a wall portion for partitioning the first catch tank 150 and the second catch tank 160. The partition wall 103 has a right partition wall 104 formed by the wall portion of the first piece 10 and a left partition wall 106 formed by the wall portion of the second piece 20. Hereinafter, these right partition wall 104 and left partition wall 106 will be described in order.

[0042] <Right partition wall> First, the right partition wall 104 will be described. As shown in FIG. 2, the right partition wall 104 has a right bottom wall 110, a right first side wall 111, a right second side wall 112, and a right third side wall 113.

[0043] As shown in FIG. 4, the right bottom wall 110 extends from the first main wall 11 into the first accommodation space 81A. The right bottom wall 110 is substantially orthogonal to the first main wall 11. That is, the right bottom wall 110 is substantially parallel to the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. With respect to the direction along this rotation axis 42Z, the dimension of the right bottom wall 110 is substantially the same as the dimension of the first peripheral wall 12. As shown in FIG. 2, the right bottom wall 110 is located between the specific portion 85A of the first peripheral wall 12 and the ring gear 42 of the planetary gear mechanism 40. The right bottom wall 110 is closer to the ring gear 42 side than the specific portion 85A of the first peripheral wall 12 and the ring gear 42. The right bottom wall 110 is located above when viewed from the rotation axis 42Z of the ring gear 42. The right bottom wall 110 extends in an arc shape centered on the rotation axis 42Z of the ring gear 42. The rear end of the arc of the right bottom wall 110 is located on the front side when viewed from the front end of the first reduction gear 51 and on the rear side when viewed from the rotation axis 42Z of the ring gear 42. Also, the front end of the arc of the right bottom wall 110 is located on the front side when viewed from the rotation axis 42Z of the ring gear 42. In a plan view from the direction along the rotation axis 42Z of the ring gear 42, the right bottom wall 110 exists over a range of 75 degrees or more, specifically approximately 90 degrees, centered on the rotation axis 42Z of the ring gear 42.

[0044] The right first side wall 111 extends upward from the rear end of the right bottom wall 110. Specifically, the right first side wall 111 is inclined so as to be located more rearward as it goes upward. The right first side wall 111 generally extends along the radial direction centered on the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The upper end of the right first side wall 111 is at a position appropriately separated from the specific portion 85A of the first main wall 11. For example, the upper end of the right first side wall 111 is located below when viewed from the rotation axis 72Z of the connection gear 72B of the second MG 72. The right first side wall 111, like the right bottom wall 110, also extends from the first main wall 11. The right first side wall 111 is substantially orthogonal to the first main wall 11. The extension length of the right first side wall 111 from the first main wall 11, that is, the dimension of the right first side wall 111 in the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40, is substantially the same as the extension length of the right bottom wall 110 from the first main wall 11.

[0045] The right second side wall 112 extends upward from a predetermined position between the rear end and the front end on the right bottom wall 110. The above-mentioned predetermined position is located on the front side when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The right second side wall 112 is inclined so as to be located more forward in the upward direction. The right second side wall 112 generally extends along the radial direction centered on the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The upper end of the right second side wall 112 is located below when viewed from the upper end of the right first side wall 111. The upper end of the right second side wall 112 reaches near a specific portion 85A of the first peripheral wall 12. There is a gap between the upper end of the right second side wall 112 and the specific portion 85A of the first peripheral wall 12. Similar to the right first side wall 111, the right second side wall 112 also extends from the first main wall 11. The extension length of the right second side wall 112 from the first main wall 11 is substantially the same as the extension length of the right first side wall 111 from the first main wall 11.

[0046]

[0047] <Left partition wall> Next, the left partition wall 106 will be described. Here, within the first accommodation space 81A, the above-described right partition wall 104 and the left partition wall 106 are configured symmetrically left and right. That is, in a plan view from the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40, the right partition wall 104 and the left partition wall 106 are in the same position. Therefore, hereinafter, the left partition wall 106 will be described in a simplified manner.

[0048] As shown in FIG. 3, the left partition wall 106 has a left bottom wall 120, a left first side wall 121, a left second side wall 122, and a left third side wall 123. As shown in FIG. 4, the left bottom wall 120 extends from the second main wall 21 into the first accommodation space 81A. As shown in FIG. 3, the left bottom wall 120 extends in an arc shape upward when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The left first side wall 121 extends upward and rearward from the rear end of the left bottom wall 120. The left second side wall 122 extends upward and forward from a predetermined position between the rear end and the front end of the left bottom wall 120. The left third side wall 123 extends upward and forward from the front end of the left bottom wall 120. The left first side wall 121, the left second side wall 122, and the left third side wall 123 also extend from the second main wall 21, similar to the left bottom wall 120. The extension lengths of the respective wall portions from the second main wall 21 are substantially the same as the extension length of the second peripheral wall 22 from the second main wall 21.

[0049] <Details of the Catch Tank> The left partition wall 106 and the right partition wall 104 described above are connected to each other in the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. That is, the left bottom wall 120 and the right bottom wall 110 constitute a continuous bottom wall 130. The left first side wall 121 and the right first side wall 111 constitute a continuous first side wall 131. The left second side wall 122 and the right second side wall 112 constitute a continuous second side wall 132. The left third side wall 123 and the right third side wall 113 constitute a continuous third side wall 133.

[0050] The bottom wall 130, the first side wall 131, and the second side wall 132 define the first catch tank 150. As described in the arrangement of the right bottom wall 110 above, the bottom wall 130 is located above when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. Therefore, the first catch tank 150 is located above when viewed from the rotation axis 42Z of this ring gear 42. As described above, the rotation axis 61Z of the ring gear 61 of the differential 60 is located slightly below when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. That is, the first catch tank 150 is also located above when viewed from the rotation axis 61Z of the ring gear 61 of the differential 60.

[0051] As described in the arrangement of the right second side wall 112 above, the second side wall 132 is inclined so as to be located more forward as it goes upward. That is, the upper part of the second side wall 132 is located more forward. Therefore, the upper end of the second side wall 132 is the foremost part among the wall portions that define the first catch tank 150. Here, in the forward and backward directions, which are the directions orthogonal to both the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40 and the upward direction, the former is referred to as the lateral direction. At this time, the upper end of the second side wall 132 constitutes the lateral end, that is, the front end, in the first catch tank 150.

[0052] As described in the arrangement of the right third side wall 113 above, the upper end of the third side wall 133 is located forward when viewed from the upper end of the second side wall 132. Therefore, due to the structure of the partition wall 103, there is a wall portion that defines the second catch tank 160 at a position downward when viewed from the upper end of the second side wall 132. That is, the second catch tank 160 is located downward when viewed from the upper end of the second side wall 132. Note that the "position downward when viewed from the upper end of the second side wall 132" described above is the position directly below when viewed from the upper end of the second side wall 132, and is the position on the virtual straight line when a virtual straight line is drawn vertically downward from the upper end of the second side wall 132. In this way, the second catch tank 160 is located downward when viewed from the upper end of the second side wall 132.

[0053] As described above, the bottom wall 130 is located above both the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40 and the rotation axis 61Z of the ring gear 61 of the differential 60. Therefore, similar to the first catch tank 150, the second catch tank 160 is located above both of these two rotation axes.

[0054] <Guard> The case 81 has a guard 180. The guard 180 is a wall portion located in the first accommodation space 81A. The guard 180 has a right guard 183 formed by the wall portion of the first piece 10 and a left guard 186 formed by the wall portion of the second piece 20. Hereinafter, the right guard 183 and the left guard 186 will be described in order.

[0055] First, the right guard 183 will be described. As shown in FIG. 2, the right guard 183 has a right horizontal wall 183A and a right vertical wall 183B. As shown in FIG. 4, the right horizontal wall 183A extends from the first main wall 11 of the first piece 10 into the first accommodation space 81A. The right horizontal wall 183A is substantially orthogonal to the first main wall 11. The extension length of the right horizontal wall 183A from the first main wall 11 is substantially the same as the extension length of the first peripheral wall 12 from the first main wall 11. As shown in FIG. 2, the right horizontal wall 183A is located between a specific portion 85A of the first peripheral wall 12 and the first catch tank 150. The right horizontal wall 183A is located above the upper end of the first side wall 131 that partitions the first catch tank 150. The right horizontal wall 183A generally follows the specific portion 85A of the first peripheral wall 12. In a plan view from the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40, the right horizontal wall 183A extends linearly. The rear end of the right horizontal wall 183A is located in front when viewed from the upper end of the first side wall 131. The rear end of the right horizontal wall 183A is located behind when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The front end of the right horizontal wall 183A is located in front when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The front end of the right horizontal wall 183A is located behind when viewed from the upper end of the right second side wall 111.

[0056] The right vertical wall 183B extends from the first main wall 11 into the first accommodation space 81A. The right vertical wall 183B is substantially orthogonal to the first main wall 11. The extension length of the right vertical wall 183B from the first main wall 11 is substantially the same as the extension length of the right horizontal wall 183A from the first main wall 11. The right vertical wall 183B extends upward and forward from the front end of the right horizontal wall 183A. The upper end of the right vertical wall 183B is located below when viewed from the rear end of the right horizontal wall 183A. The upper end of the right vertical wall 183B reaches the vicinity of the specific portion 85A in the first peripheral wall 12. There is a gap between the upper end of the right vertical wall 183B and the specific portion 85A of the first peripheral wall 12.

[0057] Next, the left guard 186 will be described. Here, in the first accommodation space 81A, the right guard 183 and the left guard 186 described above are configured symmetrically left and right. That is, in a plan view from the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40, the right guard 183 and the left guard 186 are in the same position. Therefore, hereinafter, the left guard 186 will be briefly described.

[0058] As shown in FIG. 3, the left guard 186 has a left horizontal wall 186A and a left vertical wall 186B. As shown in FIG. 4, the left horizontal wall 186A extends from the second main wall 21 of the second piece 20 into the first accommodation space 81A. As shown in FIG. 3, the left horizontal wall 186A is provided along the specific portion 85A between the specific portion 85A of the second peripheral wall 22 and the first catch tank 150. The left vertical wall 186B extends upward and forward from the front end of the left horizontal wall 186A. The left vertical wall 186B also extends from the second main wall 21. The extension length of the left horizontal wall 186A from the second main wall 21 and the extension length of the left vertical wall 186B from the second main wall 21 are substantially the same as the extension length of the second peripheral wall 22 from the second main wall 21.

[0059] The left guard 186 and the right guard 183 described above are connected to each other in the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. That is, as shown in FIG. 4, the left horizontal wall 186A and the right horizontal wall 183A form a continuous horizontal wall 180A. Similarly, the left vertical wall 186B and the right vertical wall 183B form a continuous vertical wall 180B. The guard 180 functions as a shielding wall that blocks oil from flowing toward the specific portion 85A of the peripheral wall 85. In addition, the horizontal wall 180A and the vertical wall 180B define an auxiliary catch tank 190 that can store oil. That is, the case 81 has the auxiliary catch tank 190 as a part of the first accommodation space 81A in addition to the first catch tank 150 and the second catch tank 160.

[0060] <About oil> As shown in Fig. 3, oil is stored at the bottom of the first housing space 81A. The oil level L is located above the lowest end of the ring gear 61 of the differential 60 and below the lowest end of the ring gear 42 of the planetary gear mechanism 40. Therefore, the ring gear 61 of the differential 60 is immersed in oil, but the ring gear 42 of the planetary gear mechanism 40 is not immersed in oil. The height of the oil level L has an upper limit depending on the height of the drive shaft 96 connected to the differential 60. In other words, the oil level L has an upper limit set to the height of the drive shaft 96, or more specifically, the height of the hole in the case 81 through which the drive shaft 96 penetrates.

[0061] <First oil supply mechanism> As shown in Figure 1, Kusu The gear 80 has a first oil supply mechanism 201. The first oil supply mechanism 201 is for lubricating each gear in the first accommodation space 81A. As shown in Fig. 3, the first oil supply mechanism 201 has a drive gear 210, an oil pump 211, a strainer 213, and a first pipe 212. Each of these components is located in the first accommodation space 81A.

[0062] As shown in FIG. 3, the drive gear 210 meshes with the ring gear 61 of the differential 60. The drive gear 210 is located at the bottom of the first accommodation space 81A. Specifically, the drive gear 210 is located on the front side and the lower side when viewed from the rotation axis 61Z of the ring gear 61 of the differential 60. Further, the drive gear 210 is located on the rear side and the lower side when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40.

[0063] The strainer 213 and the oil pump 211 are located in the vicinity of the drive gear 210. The strainer 213 is a passage for sucking oil. The strainer 213 is connected to the oil pump 211. The oil pump 211 pumps oil in response to the rotation of the drive gear 210. The first end of the first pipe 212 is connected to the oil pump 211. The first pipe 212 extends upward from the first end. Although not shown, the first pipe 212 passes around the ring gear 61 of the differential 60, the first reduction gear 51, and the connection gear 72B of the second MG 72. There are openings in the middle of the first pipe 212 for supplying oil to these gears. The second end of the first pipe 212 serves as an outlet 212A for discharging oil. The outlet 212A is located on the front side when viewed from the rotation axis 51Z of the first reduction gear 51. The outlet 212A is located on the rear side when viewed from the upper end of the first side wall 131 that partitions the first catch tank 150. The outlet 212A is located on the upper side when viewed from the upper end of the first side wall 131. The outlet 212A is located on the lower side when viewed from the rear end of the transverse wall 180A of the guard 180. At this position, the outlet 212A opens forward.

[0064] Note that, as shown in FIG. 4, the outlet 212A is located on a plane (hereinafter referred to as a virtual plane) A obtained by virtually extending the joint surface between the first peripheral wall 12 of the first piece 10 and the second peripheral wall 22 of the second piece 20. Although not shown, the outlet 212A is fixed at the above position using a connecting component such as a bracket extending from the second main wall 21.

[0065] <Second Oil Supply Mechanism> As shown in Figure 1, Kusu The oil supply mechanism 80 has a second oil supply mechanism 202. The second oil supply mechanism 202 is an oil supply path separate from the first oil supply mechanism 201. The second oil supply mechanism 202 is for cooling the main body 71P of the first MG 71 and the main body 72P of the second MG 72 in the second housing space 81B. The second oil supply mechanism 202 includes a pump driven by the crankshaft 99A, an oil passage connected to the pump, an oil cooler for cooling the oil flowing in the oil passage, and the like. The second oil supply mechanism 202 has a second pipe 220 that constitutes a part of the oil passage.

[0066] 3, the second piping 220 extends from the second housing space 81B located on the rear side of the second main wall 21 to the first housing space 81A on the front side of the paper, and then extends through the first housing space 81A. The second piping 220 then returns from the first housing space 81A to the second housing space 81B. That is, the second piping 220 penetrates the second main wall 21.

[0067] In the first housing space 81A, the second piping 220 passes between the first catch tank 150 and the guard 180. The second piping 220 extends along the side wall 180A from the front end to the rear end of the side wall 180A. As shown in FIG. 4, the portion of the second piping 220 that extends along the side wall 180A is located on the imaginary plane A that is an extension of the joint surface between the first peripheral wall 12 of the first piece 10 and the second peripheral wall 22 of the second piece 20. Although not shown, the second piping 220 is fixed in the above position by using a connecting part such as a bracket extending from the second main wall 21.

[0068] <Operation of the embodiment> (A) Basic oil distribution channels The ring gear 61 of the differential 60 rotates upon receiving the power of the internal combustion engine 99, the first MG 71, and the second MG 72. When the ring gear 61 rotates, the oil pump 211 is driven in response to the rotation of the drive gear 210 meshing with the ring gear 61. Then, as indicated by the dotted arrow Y1 in FIG. 3, the oil pump 211 sucks in the oil accumulated at the bottom of the first accommodation space 81A via the strainer 213. And the oil pump 211 pumps the sucked oil to the outlet portion 212A of the first pipe 212. As indicated by the dotted arrow Y2 in FIG. 3, the outlet portion 212A of the first pipe 212 discharges the oil forward.

[0069] As described above, the outlet portion 212A of the first pipe 212 is located below when viewed from the rear end of the transverse wall 180A of the guard 180 and above when viewed from the first catch tank 150. Along with this, the oil discharged from the outlet portion 212A mainly reaches the first catch tank 150 through any one of the following three paths.

[0070] (a) As indicated by the dotted arrow Y3 in FIG. 3, the oil adheres to the lower surface of the transverse wall 180A of the guard 180. Then, the oil falls from the lower surface of the transverse wall 180A and reaches the first catch tank 150.

[0071] (b) The oil adheres to the second pipe 220 located between the transverse wall 180A of the guard 180 and the first catch tank 150. And the oil falls from the second pipe 220 and reaches the first catch tank 150.

[0072] (c) The oil directly heads from the outlet portion 212A toward the first catch tank 150. Here, the ring gear 61 rotates clockwise in FIG. 3. When the ring gear 61 rotates, as indicated by the dotted arrow W in FIG. 3, the ring gear 61 rolls up the oil accumulated at the bottom of the first accommodation space 81A. This oil heads toward the vicinity of the outlet portion 212A of the first pipe 212. This oil also reaches the first catch tank 150 through the above three paths.

[0073] In some cases, the oil discharged from the outlet portion 212A of the first pipe 212 and the oil lifted by the ring gear 61 may reach the upper side when viewed from the transverse wall 180A of the guard 180. In this case, the oil accumulates in the auxiliary catch tank 190 partitioned by the guard 180. When the amount of oil in the auxiliary catch tank 190 increases, the oil reaches the first catch tank 150 through the gap between the longitudinal wall 180B of the guard 180 and the peripheral wall 85.

[0074] The oil accumulates in the first catch tank 150 through the above-described path. Now, the upper end of the second side wall 132 partitioning the first catch tank 150 is located below the upper end of the first side wall 131 when viewed from the upper end of the first side wall 131. Accordingly, when the amount of oil in the first catch tank 150 exceeds the amount that can be stored in the first catch tank 150, the oil in the first catch tank 150 overruns the upper end of the second side wall 132 instead of the upper end of the first side wall 131. As described above, the second catch tank 160 is located downward of the upper end of the second side wall 132. Therefore, as indicated by the dotted arrow Y4 in FIG. 3, the oil that has overridden the upper end of the second side wall 132, that is, the oil that has overflowed from the first catch tank 150, reaches the second catch tank 160 through the gap between the upper end of the second side wall 132 and the peripheral wall 85. Then, the second catch tank 160 receives the oil that has overflowed from the first catch tank 150.

[0075] The oil accumulates in the second catch tank 160 as described above. Now, the upper end of the third side wall 133 partitioning the second catch tank 160 is located below the upper end of the second side wall 132 when viewed from the upper end of the second side wall 132. Accordingly, when the amount of oil accumulated in the second catch tank 160 exceeds the amount that can be stored in the second catch tank 160, the oil in the second catch tank 160 overruns the upper end of the third side wall 133 instead of the upper end of the second side wall 132. That is, as indicated by the dotted arrow Y5 in FIG. 3, the oil overflows from the second catch tank 160 and returns from the second catch tank 160 to the bottom of the first accommodation space 81A through the gap between the upper end of the third side wall 133 and the peripheral wall 85.

[0076] (B) Oil flow when driving on a downhill road When the vehicle 500 travels on a downhill road, the case 81 tilts forward together with the vehicle 500. That is, as shown in FIG. 5, among the triangles of the second main wall 21, the frontmost vertex is positioned downward when viewed from the rearmost vertex. In this case, the inclination angle of the second side wall 132 partitioning the first catch tank 150 with respect to the horizontal plane H becomes smaller than when the vehicle 500 is traveling on a flat road. That is, the second side wall 132 becomes closer to horizontal. Therefore, as indicated by the dotted arrow V1 in FIG. 5, the oil accumulated in the first catch tank 150 easily climbs over the upper end of the second side wall 132. And when the vehicle 500 travels on a downhill road, even if the amount of oil accumulated in the first catch tank 150 is less than the amount that can be stored in the first catch tank 150, the oil flows down to the second catch tank 160. Similarly, when the vehicle 500 travels on a downhill road, the inclination angle of the third side wall 133 with respect to the horizontal plane H becomes smaller. Therefore, as indicated by the dotted arrow V2 in FIG. 5, the oil accumulated in the second catch tank 160 easily climbs over the upper end of the third side wall 133. Therefore, when the vehicle 500 travels on a downhill road, even if the amount of oil accumulated in the second catch tank 160 is less than the amount that can be stored in the second catch tank 160, the oil flows from the second catch tank 160 to the bottom of the first accommodation space 81A.

[0077] <Effects of the embodiment> (1) When installing the transaxle 80 in the vehicle 500 Kusu on the vehicle 500, the transaxle KusuIt is required to design the case 81 forming the outer contour of the hub 80 to be as small as possible. In relation to this, the case 81 is shaped according to the arrangement of the gears within the case 81 so that the empty space within the case 81 can be minimized. And, the peripheral wall 85 of the case 81 in the present embodiment is triangular and surrounds the planetary gear mechanism 40, the differential 60, and the first reduction gear 51. At the same time, the distance between the specific portion 85A of the peripheral wall 85 and the ring gear 42 of the planetary gear mechanism 40 is correspondingly narrow. In this case, when providing a catch tank between the specific portion 85A of the peripheral wall 85 and the ring gear 42 of the planetary gear mechanism 40, it is difficult to secure a large space for the catch tank.

[0078] In this regard, in the present embodiment, the first catch tank 150 and the second catch tank 160 are partitioned along the outer edge of the ring gear 42 of the planetary gear mechanism 40. That is, by utilizing the outer peripheral space of the ring gear 42 and arranging them in an arc shape in the space, the first catch tank 150 and the second catch tank 160 are provided. By providing the catch tank in this way, even if the distance between the ring gear 42 and the specific portion 85A of the peripheral wall 85 is narrow, the capacity of the oil that can be stored in the catch tank can be increased. Therefore, the stirring resistance of the ring gear 61 of the differential 60 can be suppressed.

[0079] (2) In the present embodiment, the drive gear 210 of the oil pump 211 is located on the front side when viewed from the rotation axis 61Z of the ring gear 61 of the differential 60 and on the rear side when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. Accordingly, the strainer 213 is located near the center of the front and rear of the bottom of the first accommodation space 81A.

[0080] Here, when the vehicle 500 travels on an inclined road, the oil accumulated at the bottom of the first accommodation space 81A will be biased towards either the front or the rear of the bottom of the first accommodation space 81A. As described above, when the vehicle 500 travels on a downhill road, as shown in FIG. 5, among the triangles of the second main wall 21, the frontmost vertex will be located on the lower side when viewed from the rearmost vertex. Accordingly, as shown by the dashed-two-dot line L1 in FIG. 5, the oil accumulated at the bottom of the first accommodation space 81A will be biased towards the front portion of the first accommodation space 81A. Conversely, when the vehicle 500 travels on an uphill road, the oil will be biased towards the rear portion of the first accommodation space 81A. Here, the amount of oil that can be stored at the bottom of the first accommodation space 81A is restricted, for example, in relation to the height of the drive shaft 96 described above and the stirring resistance described in (1) above. Therefore, the amount of oil at the bottom of the first accommodation space 81A cannot be increased significantly. For this reason too, when the vehicle 500 travels on an inclined road and the oil stored at the bottom of the first accommodation space 81A is biased towards the front and rear of the bottom, for example, as shown by the dashed-two-dot line L1 in FIG. 5, the oil level of the oil may be located on the lower side when viewed from the strainer 213. When the oil level of the oil is located on the lower side when viewed from the strainer 213, air suction occurs at the strainer 213. As described above, there is an opening in the middle of the first pipe 212 for supplying oil to each gear housed in the first accommodation space 81A. When air suction occurs at the strainer 213, the amount of oil flowing through the first pipe 212 becomes insufficient, and the oil cannot be sufficiently supplied to each gear.

[0081] Now, a ring gear 61 of the differential 60 exists in the rearward and downward portion of the first accommodation space 81A. Therefore, when the vehicle 500 travels on an uphill road and the oil at the bottom of the first accommodation space 81A is biased towards the rear portion, a part of this ring gear 61 will be in a state of being immersed in the oil. When the ring gear 61 rotates, the ring gear 61 rolls up the oil. Therefore, even if air suction occurs at the strainer 213, oil can be supplied to each gear housed in the first accommodation space 81A.

[0082] On the other hand, when the vehicle 500 travels on a downhill road and the oil at the bottom of the first accommodation space 81A is biased toward the front portion, as shown by the two-dot chain line L1 in FIG. 5, the oil level may exist below the ring gear 61 of the differential 60 when viewed from below. In this case, the ring gear 61 cannot lift the oil. That is, for each gear, neither the oil supply utilizing the lifting of the ring gear 61 nor the oil supply through the first pipe 212 can be performed.

[0083] In this regard, in the present embodiment, among the first side wall 131 and the second side wall 132 partitioning the first catch tank 150, the upper end of the second side wall 132 is located below the upper end of the first side wall 131 when viewed from above. Further, among the second side wall 132 and the third side wall 133 partitioning the second catch tank 160, the upper end of the third side wall 133 is located below the upper end of the second side wall 132 when viewed from above. Therefore, as described in the above operation, basically, the oil easily reaches the front side, that is, from the first catch tank 150 to the second catch tank 160, and further from the second catch tank 160 to the bottom of the first accommodation space 81A. When the vehicle 500 travels on a downhill road, the inclination angles of the second side wall 132 and the third side wall 133 with respect to the horizontal plane H are smaller than when the vehicle 500 travels on a flat road. Therefore, the oil easily reaches from the first catch tank 150 to the second catch tank 160 as shown by the dotted arrow V1 in FIG. 5, and further from the second catch tank 160 to the bottom of the first accommodation space 81A as shown by the dotted arrow V2. In this way, by sufficiently returning the oil from the catch tank to the bottom of the first accommodation space 81A, during traveling on a downhill road, as shown by the two-dot chain line L2 in FIG. 5, the oil level of the oil accumulated at the bottom of the first accommodation space 81A becomes higher than the suction port of the strainer 213. Therefore, when the vehicle 500 travels on a downhill road, the strainer 213 does not generate air suction. Thus, when the vehicle 500 travels on a downhill road, the oil can be sufficiently supplied to each gear in the first accommodation space 81A.

[0084] (3) In this embodiment, the first side wall 131 partitioning the first catch tank 150 is inclined so as to be positioned more rearward as it faces upward. Similarly, the second side wall 132 is inclined so as to be positioned more forward as it faces upward. The advantages of this will be explained.

[0085] As described above, when the vehicle 500 travels on a downhill road, as shown in FIG. 5, the case 81 tilts forward. When the second side wall 132 is inclined forward with respect to the upward direction as in this embodiment, for example, compared to the case where the second side wall is not inclined with respect to the upward direction, the inclination angle of the second side wall 132 with respect to the horizontal plane H when the case 81 tilts forward becomes smaller. Therefore, in the configuration of this embodiment, it is easier for the oil in the first catch tank 150 to reach the second catch tank 160. Moreover, when the second side wall 132 is inclined forward with respect to the upward direction, the volume of the first catch tank 150 can be increased by the amount of the inclination. Similarly, in this embodiment, by inclining the first side wall 131 rearward, the volume of the first catch tank 150 can be increased by the amount of the inclination.

[0086] The same can be said for the third side wall 133 partitioning the second catch tank 160. That is, in this embodiment, the third side wall 133 is inclined so as to be positioned more forward as it faces upward. Thereby, similar to the second side wall 132 described above, when the vehicle 500 travels on a downhill road and the case 81 tilts forward, it is easier for the oil in the second catch tank 160 to reach the bottom of the first accommodation space 81A. Moreover, by the third side wall 133 being inclined forward, the volume of the second catch tank 160 can be increased by the amount of the inclination.

[0087] (4) In this embodiment, the bottom wall 130 of the partition wall 103 exists in a range of 75 degrees or more centered on the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40 in a plan view from the direction along the rotation axis 42Z of the ring gear 42. When arranging the catch tank in the outer peripheral space of the ring gear 42, in this way, the bottom wall 130 can be extended over a range of 75 degrees or more. Then, by increasing the arc length of the bottom wall 130 to such an extent that it extends over 75 degrees or more, a large volume can be ensured for the first catch tank 150 and the second catch tank 160. Moreover, since the shape of the bottom wall 130 is arc-shaped, the rigidity of the bottom wall 130 can be ensured even when the bottom wall 130 is appropriately lengthened as described above.

[0088] (5) The outlet portion 212A of the first pipe 212 discharges oil forcefully. Also, the ring gear 61 of the differential 60 also forcefully rolls up the oil. When these oils head toward the peripheral wall 85, the oils will collide forcefully with the peripheral wall 85. In this case, there is a possibility that oil may ooze out from the joint surface between the first peripheral wall 12 of the first piece 10 and the second peripheral wall 22 of the second piece 20.

[0089] In this regard, in the present embodiment, a transverse wall 180A of the guard 180 is present between the first catch tank 150 and a specific portion 85A of the peripheral wall 85. Therefore, as described in the above operation, the oil discharged from the outlet portion 212A of the first pipe 212 and the oil wound up by the ring gear 61 of the differential 60 basically hit the transverse wall 180A of the guard 180 before hitting the specific portion 85A of the peripheral wall 85. Further, below the guard 180 as viewed from the guard 180, a second pipe 220 extends along the lower surface of the guard 180. This second pipe 220 is located at the same position as the outlet portion 212A with respect to the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. Therefore, the oil discharged from the outlet portion 212A can hit the second pipe 220 before hitting the guard 180. From these facts, it is possible to prevent the oil from the outlet portion 212A and the ring gear 61 from directly reaching the peripheral wall 85 and colliding strongly with the specific portion 85A of the peripheral wall 85. As a result, it is possible to prevent the oil from oozing out from the joint surface between the first peripheral wall 12 of the first piece 10 and the second peripheral wall 22 of the second piece 20.

[0090] As described in the above operation, when the oil flows from the first catch tank 150 to the second catch tank 160, the oil passes through the gap between the upper end of the second side wall 132 and the peripheral wall 85. That is, the oil can come into contact with the peripheral wall 85 in a series of oil flow paths. However, when the oil flows from the first catch tank 150 to the second catch tank 160, the oil does not strongly collide with the peripheral wall 85, but overflows from the first catch tank 150 and gently flows through the above gap. Therefore, when the oil flows from the first catch tank 150 to the second catch tank 160, the possibility of the oil oozing out from the joint surface between the first peripheral wall 12 of the first piece 10 and the second peripheral wall 22 of the second piece 20 is low.

[0091] Similarly, when the oil flows from the second catch tank 160 to the bottom of the first accommodation space 81A, instead of vigorously colliding with the peripheral wall 85, the oil overflows from the second catch tank 160 and gently flows through the gap between the upper end of the third side wall 133 and the peripheral wall 85. Therefore, the possibility of the oil oozing out from the joint surface between the first peripheral wall 12 of the first piece 10 and the second peripheral wall 22 of the second piece 20 is low.

[0092] (6) In the present embodiment, in the first piece 10, the extension length of the first peripheral wall 12 from the first main wall 11 is the same as the extension length of the right bottom wall 110 from the first main wall 11. Similarly, for the right first side wall 111, the right second side wall 112, and the right third side wall 113, the extension lengths of these wall portions from the first main wall 11 are the same as that of the first peripheral wall 12. In this case, when manufacturing the first piece 10, the joint surfaces of these wall portions with the second piece 20 may be machined flush, and there is no need to individually adjust the extension lengths of these wall portions. Therefore, it is not difficult to manufacture the first piece 10. The same applies to the second piece 20 in this regard.

[0093] <Modified Example> This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0094] · The configuration of the guard 180 is not limited to the examples of the above embodiments. The guard 180 may have any configuration that can prevent the oil from hitting the peripheral wall 85. For example, the upper end of the vertical wall 180B may reach the peripheral wall 85 of the case 81. In this case, for example, a through hole for communicating the auxiliary catch tank 190 with the outside of the auxiliary catch tank 190 may be provided in the vertical wall 180B. Then, the oil may be discharged from the auxiliary catch tank 190 through the through hole. Further, the guard 180 may not have a function of storing oil. That is, the vertical wall 180B may be abolished. Also, the guard 180 may not be connected from the first main wall 11 to the second main wall 21. For example, one of the right guard 183 and the left guard 186 may be abolished. As long as there is somewhat of the transverse wall 180A of the guard 180, the oil can be prevented from hitting the peripheral wall 85.

[0095] · The guard 180 may be abolished. Regardless of the presence or absence of the guard 180, as long as the first catch tank 150 and the second catch tank 160 exist. As long as the first catch tank 150 and the second catch tank 160 exist, since oil can be stored in these catch tanks, the stirring resistance of the ring gear 61 of the differential 60 can be suppressed.

[0096] · The configuration of the partition wall that partitions the first catch tank and the second catch tank is not limited to the examples of the above embodiments. As long as the first catch tank satisfies the following first condition and the second catch tank satisfies the following second condition, it does not matter where and in what shape the partition wall is provided. The first condition has the following two items.

[0097] (A1) The first catch tank is located above when viewed from the rotation axis 61Z of the ring gear 61 of the differential 60. (A2) The first catch tank is located above from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40 The second condition has the following three items.

[0098] (B1) The second catch tank is located above when viewed from the rotation axis 61Z of the ring gear 61 of the differential 60. (B2) The second catch tank is located above when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40.

[0099] (B3) The second catch tank is located downward when viewed from the lateral end in the first catch tank. · The configuration of the bottom wall 130 is not limited to the example of the above embodiment. The positions of the rear end and the front end of the bottom wall 130 may be changed from the example of the above embodiment. For example, the position of the rear end of the bottom wall 130 may be located on the front side when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. Also, the arc length of the bottom wall 130 may be changed from 90 degrees set in the above embodiment. That is, in a plan view from the direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40, the bottom wall 130 may exist over a range of 90 degrees or more centered on the rotation axis 42Z. Conversely, the bottom wall 130 may exist within a range of 90 degrees or less. Considering constraints such as avoiding interference with other components in addition to the volume of the catch tank, the arc length of the bottom wall 130 and the positions of the front end and the rear end of the bottom wall 130 may be appropriately determined.

[0100] · The configuration of the first side wall 131 is not limited to the example of the above embodiment. For example, the first side wall 131 may not be inclined so as to be located more rearward as it goes upward. That is, the first side wall 131 may extend upward. The first side wall 131 may be bent or curved while extending upward. The first side wall 131 only needs to extend upward from the bottom wall 130. If so, the first catch tank 150 can be partitioned.

[0101] · Similar to the modification example of the first side wall 131, the configuration of the second side wall 132 is not limited to the example of the above embodiment. Similar to the first side wall 131, the second side wall 132 may not be inclined so as to be positioned more forward as it goes upward, or may be bent or curved in the middle. Also, the upper end of the second side wall 132 may reach the peripheral wall 85. In this case, a through hole for communicating the first catch tank 150 and the second catch tank 160 may be provided in the second side wall 132. The second side wall 132 only needs to extend upward from the bottom wall 130.

[0102] · The predetermined position, which is the installation position of the second side wall 132 on the bottom wall 130, is not limited to the example of the above embodiment. The predetermined position may be, for example, the rear side when viewed from the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40. The predetermined position may be between the first side wall 131 and the third side wall 133 and may be a position away from these two side walls.

[0103] · Similar to the modification example of the second side wall 132, the configuration of the third side wall 133 is not limited to the example of the above embodiment. The third side wall 133 only needs to extend upward from the bottom wall 130.

[0104] · It is not essential that the upper end of the third side wall 133 is positioned below the upper end of the second side wall 132 when viewed from the upper end of the second side wall 132. As long as the above first condition and second condition are satisfied, the positional relationship between the upper end of the third side wall 133 and the upper end of the second side wall 132 does not matter.

[0105] · The number of side walls extending upward from the bottom wall 130 may be four or more. That is, another side wall may be provided between the first side wall 131 and the second side wall 132, or between the second side wall 132 and the third side wall 133. And thereby, the number of catch tanks may be increased. It is preferable for sequentially flowing down the oil to the front catch tank if the upper end of the side wall positioned more forward is lower.

[0106] ·In the above-described embodiment, the second side wall 132 was used as a common wall portion that partitions the first catch tank 150 and the second catch tank 160. However, without using such a common side wall, the first catch tank may be partitioned by a side wall dedicated to the first catch tank, and the second catch tank may be partitioned by a side wall dedicated to the second catch tank.

[0107] ·The bottom wall that partitions the first catch tank and the bottom wall that partitions the second catch tank may not be connected together, and independent bottom walls may be provided for each catch tank. That is, the bottom walls of the two catch tanks may be located at positions separated from each other. When such independent bottom walls are employed, for example, in a plan view from a direction along the rotation axis 42Z of the ring gear 42 of the planetary gear mechanism 40, the bottom wall may be linear. That is, the bottom wall may be flat without being curved. The bottom wall may have any appropriate configuration as long as it partitions the bottom portions of the first catch tank and the second catch tank.

[0108] ·The partition wall may not extend from the first main wall 11 to the second main wall 21. For example, one of the right partition wall and the left partition wall may be abolished. ·The partition wall may have a shape such that there is no boundary between the side wall and the bottom wall. That is, the partition wall may have a shape that is curved as a whole without having a bent portion between the side wall and the bottom wall.

[0109] ·The extension length of the partition wall from the main wall may be different from the extension length of the peripheral wall from the main wall. Further, the extension lengths from the main wall may be different between the bottom wall and the side wall. ·There may be a deviation in the vertical, front-rear, and left-right directions between the power transmission device and the vehicle. Even in this case, the first catch tank and the second catch tank may be provided so that the first condition and the second condition are satisfied with reference to the upward direction of the power transmission device, the rotation axis of the ring gear of the differential, and the lateral direction that is orthogonal to both of them.

[0110] ·The overall configuration of the power transmission device is not limited to the examples of the above embodiments. The power transmission device only needs to have a differential, a gear mechanism, and a case for housing them. And the gear mechanism only needs to transmit power from the drive source of the vehicle to the ring gear of the differential and have a specific gear that rotates about a rotation axis parallel to the rotation axis of the ring gear of the differential.

[0111] ·As described in the above modification example, the specific gear is not limited to the ring gear 42 of the planetary gear mechanism 40. ·The arrangement of the gears in the case can vary according to the configuration of the power transmission device. And the configuration of the case can vary according to the arrangement of the gears housed in the case, etc. For example, the shape of the main wall may not be triangular but rectangular or circular. Also, in the case, there may be no main walls facing each other. Depending on the shape of the case, etc., the number of pieces constituting the case and the configuration of each piece can also vary. Even when the configuration of the case is different from the above embodiments, the first catch tank and the second catch tank may be provided in the case so that the first condition and the second condition are satisfied.

Explanation of Signs

[0112] 10…First piece 11…First main wall 20…Second piece 21…Second main wall 40…Planetary gear mechanism 42…Ring gear 60…Differential 61…Ring gear 80…Transaxle Kusu le 81…Case 81A…First accommodation space 85…Peripheral wall 97…Drive wheel 130…Bottom wall 131…First side wall 132…Second side wall 133…Third side wall 150…First catch tank 160…Second catch tank 180…Guard 500…Vehicle

Claims

1. A gear mechanism that transmits power from a vehicle's drive source, a differential that allows a difference in rotational speed to occur between the left and right drive wheels of the vehicle, to which power is transmitted from the gear mechanism, a case that houses the gear mechanism and the differential, and an oil supply mechanism, wherein the differential has a ring gear to which power from the gear mechanism is transmitted, when the rotation axis of the ring gear is defined as the first rotation axis, the gear mechanism has a specific gear that rotates about a second rotation axis parallel to the first rotation axis, the case has an accommodation space that houses the ring gear and the specific gear, the case includes a first catch tank and a second catch tank capable of storing oil as part of the accommodation space, when a specific direction among the directions orthogonal to the first rotation axis is defined as the upward direction, the first catch tank is located on the upward side when viewed from the first rotation axis and on the upward side when viewed from the second rotation axis, when the direction opposite to the upward direction is defined as the downward direction and the direction orthogonal to both the first rotation axis and the upward direction is defined as the lateral direction, the second catch tank is located on the upward side when viewed from the first rotation axis, on the upward side when viewed from the second rotation axis, and on the downward side when viewed from the end in the lateral direction of the first catch tank, the case includes a first main wall and a second main wall facing each other, a first peripheral wall extending parallel to the first rotation axis from the first main wall, a second peripheral wall extending parallel to the first rotation axis from the second main wall and joined to the first peripheral wall, partitioning the accommodation space together with the first main wall, the second main wall, and the first peripheral wall, a partition wall formed by connecting a wall portion extending from the first main wall and a wall portion extending from the second main wall, partitioning the first catch tank and the second catch tank, a guard formed by connecting a wall portion extending from the first main wall and a wall portion extending from the second main wall, located on the upward side when viewed from the first catch tank and within the range of the first catch tank in the lateral direction, the oil supply mechanism includes an oil pump located on the downward side when viewed from the first rotation axis, for pumping oil, a first pipe having a first end connected to the oil pump and a second end open, a second pipe having a portion passing between the first catch tank and the guard; the second end of the first pipe is located on the upward side as viewed from the first catch tank, on the side opposite to the first catch tank across the end in the direction opposite to the lateral direction in the first catch tank, and on a plane obtained by virtually extending the joint surface between the first peripheral wall and the second peripheral wall, and is open in the lateral direction; the guard extends from a position on the downward side of the second end of the first pipe to a position on the upward side of the second end; the portion of the second pipe passing between the first catch tank and the guard extends from a position on the downward side of the second end of the first pipe to a position on the upward side of the second end and is located on the plane; Power transmission device.

2. The first peripheral wall and the second peripheral wall constitute an integral peripheral wall. The partition wall is a bottom wall located between the specific gear and the peripheral wall and extending in an arc shape centered on the second rotation axis; a first side wall extending upward from the bottom wall; a second side wall extending upward from the bottom wall and separated from the first side wall; a third side wall extending upward from the bottom wall and located on the side opposite to the first side wall across the second side wall; and includes the first catch tank is defined by the bottom wall, the first side wall, and the second side wall; the second catch tank is defined by the bottom wall, the second side wall, and the third side wall. The power transmission device according to claim 1.

3. The upper end of the third side wall is located on the downward side as viewed from the upper end of the second side wall. The power transmission device according to claim 2.

4. In a plan view from the direction along the second rotation axis, the bottom wall exists over a range of 75 degrees or more centered on the second rotation axis. The power transmission device according to claim 2 or 3.

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