Power transmission device

Abstract

To provide a power transmission device capable of being miniaturized.SOLUTION: In the power transmission device 1 including the casing 3, the drive shaft 59 rotatably housed in the casing 3, the intermediate shaft 87 rotatably housed in the casing 3 and capable of transmitting power to and from the drive shaft 59, and the differential mechanism 17 rotatably housed in the casing 3 and having the differential case 105 capable of transmitting power to and from the intermediate shaft 87, the intermediate shaft 87 has the small-diameter gear part 103 and the large-diameter gear part 101 having a larger diameter than the small-diameter gear part 103, and the large-diameter gear part 101 is disposed axially between the pair of bearings 119121 and rotatably supporting the differential case 105.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power transmission device. [Background technology]

[0002] A conventional power transmission device includes a casing, a second input member as a drive shaft rotatably housed in the casing, a first countershaft as an intermediate shaft rotatably housed in the casing and capable of transmitting power between the second input member, and a differential mechanism having a differential case rotatably housed in the casing and capable of transmitting power between the first countershaft (see Patent Document 1).

[0003] In this power transmission device, the first countershaft has a sixth gear as a small-diameter gear portion and a fifth gear as a large-diameter gear portion with a diameter larger than that of the sixth gear. By making the diameters of the fifth gear and the sixth gear on the first countershaft different, it is possible to vary the speed ratio transmitted between the second input member and the first countershaft. By selectively disposing the fifth gear and the sixth gear, it is possible to select the driving force transmitted from the second input member to the differential mechanism depending on the vehicle's running conditions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 039134 Summary of the Invention [Problem to be solved by the invention]

[0005] In the power transmission device of Patent Document 1, the large-diameter gear portion of the intermediate shaft is disposed radially overlapping one of a pair of bearings that rotatably support the differential case, which results in the large-diameter gear portion and the differential mechanism being disposed apart in the axial direction of the intermediate shaft, resulting in an increase in the size of the device.

[0006] The present invention has been made in view of the problems inherent in the prior art, and an object of the present invention is to provide a power transmission device that can be made compact. [Means for solving the problem]

[0007] The power transmission device according to this embodiment comprises a casing, a drive shaft rotatably accommodated in the casing, an intermediate shaft rotatably accommodated in the casing and capable of transmitting power between the drive shaft, and a differential mechanism having a differential case rotatably accommodated in the casing and capable of transmitting power between the intermediate shaft, wherein the intermediate shaft has a small diameter gear portion and a large diameter gear portion larger in diameter than the small diameter gear portion, and the large diameter gear portion is disposed axially between a pair of bearings that rotatably support the differential case. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a power transmission device that can be made compact. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a power transmission device according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram of a power transmission device according to an embodiment of the present invention when viewed from the side; [Figure 3] 2 is a schematic diagram showing the arrangement of a large diameter gear portion and a small diameter gear portion in a casing of the power transmission device according to the embodiment. FIG. [Figure 4] 5 is a schematic diagram showing a comparative example of the arrangement of the large diameter gear portion and the small diameter gear portion in the casing of the power transmission device according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The power transmission device according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0011] As shown in FIG. 1, a power transmission device 1 according to this embodiment is disposed, for example, in a power transmission path of a vehicle, between a drive source and left and right drive wheels. The drive source includes an electric motor 5 (see FIG. 2) and an engine 7 (see FIG. 2). The drive force of the electric motor 5 is transmitted to a differential mechanism 17 via a first transmission mechanism 11, and the drive force is distributed to the left and right drive wheels via a pair of output shafts (not shown). The drive force of the engine 7 is transmitted to the differential mechanism 17 via a third transmission mechanism 15, and the drive force is distributed to the left and right drive wheels via a pair of output shafts. Meanwhile, the drive force of the engine 7 drives a generator 9 (see FIG. 2) via a second transmission mechanism 13, and charges a power source such as a battery or a storage battery.

[0012] As shown in Figures 1 to 3, the power transmission device 1 includes a casing 3, an electric motor 5, an engine 7, a generator 9, a first transmission mechanism 11, a second transmission mechanism 13, a third transmission mechanism 15, and a differential mechanism 17.

[0013] The casing 3 is a stationary member fixed to the vehicle, and has an internal storage space capable of storing the first transmission mechanism 11, the second transmission mechanism 13, the third transmission mechanism 15, and the differential mechanism 17. The casing 3 is composed of at least two divided members so as to have a dividing surface 19 that is perpendicular to the intermediate shaft 87 of the third transmission mechanism 15. The interior of the casing 3 contains lubricating oil that lubricates and cools the meshing parts and sliding parts of the gears.

[0014] The electric motor 5 includes a stator (not shown) and a rotor 21. The stator is disposed outside the casing 3 on one side of the first transmission mechanism 11, the second transmission mechanism 13, and the third transmission mechanism 15 in the direction of the rotation axis. The stator is electrically connected to a controller (not shown) that controls the energization and to a power source that supplies electric power. The rotor 21 is disposed rotatably via bearings 23 (only one of which is shown) on the outer periphery on both axial sides. The rotor 21 is rotated by energizing the stator. One end of the rotor 21 is disposed inside the casing 3, and power can be transmitted between it and the first transmission mechanism 11.

[0015] The engine 7 is disposed outside the casing 3 on the other side of the first transmission mechanism 11, the second transmission mechanism 13, and the third transmission mechanism 15 in the direction of the rotation axis. An output shaft (not shown) of the engine 7 is disposed so as to be able to transmit power to the second transmission mechanism 13 via an interrupter (not shown) such as a dry single-plate clutch. The driving force of the engine 7 is output to the second transmission mechanism 13 via the interrupter in the connected state.

[0016] The generator 9 includes a stator (not shown) and a rotor 25. The stator is disposed outside the casing 3 on one side of the first transmission mechanism 11, the second transmission mechanism 13, and the third transmission mechanism 15 in the direction of the rotation axis. The stator is electrically connected to a controller (not shown) that controls the energization and to a power source to be charged. The rotor 25 is disposed rotatably via bearings 27 (only one of which is shown) on both axially opposite outer peripheries. The rotor 25 is rotated by the driving force of the engine 7 via the second transmission mechanism 13, and charges the power source via the stator. One end of the rotor 25 is disposed inside the casing 3, and power can be transmitted between the rotor 25 and the second transmission mechanism 13.

[0017] The first transmission mechanism 11 is disposed on a power transmission path between the electric motor 5 and the differential mechanism 17. The first transmission mechanism 11 includes a motor-side drive shaft 29, a motor-side intermediate shaft 31, a first gear set 33, a motor clutch unit 35, a motor-side pinion 37, and a park lock gear unit 39.

[0018] The motor-side drive shaft 29 is rotatably supported on the casing 3 via bearings 41 and 43 on both axial ends thereof. The rotational axis of the motor-side drive shaft 29 is arranged concentrically with the rotational axis of the rotor 21 of the electric motor 5. One end of the motor-side drive shaft 29 is connected to the rotor 21 of the electric motor 5 via a connecting portion so as to be rotatable integrally therewith. The motor-side drive shaft 29 is rotated by the rotation of the rotor 21 of the electric motor 5.

[0019] The motor-side intermediate shaft 31 is rotatably supported on the casing 3 via bearings 45 and 47 on both axial ends thereof. The motor-side intermediate shaft 31 is arranged such that its rotation axis is parallel to the rotation axis of the motor-side drive shaft 29.

[0020] The first gear set 33 is provided to be able to transmit power between the motor-side drive shaft 29 and the motor-side intermediate shaft 31, and has a motor gear portion 49 and a motor-side large-diameter gear portion 51. The motor gear portion 49 is formed as a single member continuous with the motor-side drive shaft 29 at the other end of the motor-side drive shaft 29. The motor-side large-diameter gear portion 51 is formed with a diameter larger than that of the motor gear portion 49 and meshes with the motor gear portion 49. The motor-side large-diameter gear portion 51 is formed separately from the motor-side intermediate shaft 31 and is disposed on the outer periphery of the motor-side intermediate shaft 31 via a bearing so as to be rotatable relative to the motor-side intermediate shaft 31. The first gear set 33 reduces the driving force from the electric motor 5 and transmits it to the motor-side intermediate shaft 31.

[0021] The motor clutch unit 35 includes an interrupting portion formed between the motor-side large-diameter gear portion 51 and the hub 53, and a sleeve 55 that interrupts the interrupting portion. The hub 53 is formed into an annular shape from a single member that is continuous with the motor-side intermediate shaft 31, and is disposed adjacent to the motor-side large-diameter gear portion 51 in the axial direction of the motor-side intermediate shaft 31. The interrupting portion includes a plurality of concave-convex engaging portions provided in the circumferential direction of the motor-side large-diameter gear portion 51, and a connecting portion provided in a splined manner on the outer periphery of the hub 53. The sleeve 55 is formed into an annular shape and is connected to the connecting portion of the hub 53 so as to be movable in the axial direction relative to the connecting portion of the hub 53 and to be rotatable integrally with the hub 53. A fork (not shown) of an actuator (not shown) engages with the outer periphery of the sleeve 55, and the sleeve 55 is moved axially.

[0022] When the sleeve 55 of the motor clutch portion 35 moves axially toward the motor-side large-diameter gear portion 51, the sleeve 55 engages with the engaging portion of the motor-side large-diameter gear portion 51, and the interrupting portion is brought into an engaged state. When the interrupting portion is engaged, the motor-side large-diameter gear portion 51 and the motor-side intermediate shaft 31 become rotatable as a unit, and the driving force from the electric motor 5 is transmitted from the motor-side drive shaft 29 to the motor-side intermediate shaft 31 via the first gear set 33.

[0023] When the sleeve 55 moves axially toward the hub 53, the motor clutch portion 35 disengages the sleeve 55 from the engaging portion of the motor-side large-diameter gear portion 51, and the disconnecting portion enters a disconnected state. When the disconnecting portion is disconnected, the motor-side large-diameter gear portion 51 and the motor-side intermediate shaft 31 become relatively rotatable, and power transmission between the electric motor 5 and the motor-side intermediate shaft 31 is interrupted.

[0024] The motor side pinion 37 is disposed at the end of the motor side intermediate shaft 31 opposite to the motor side large diameter gear portion 51 in the axial direction. The motor side pinion 37 is formed of a single member that is continuous with the motor side intermediate shaft 31 and attached to the outer periphery of the motor side intermediate shaft 31. The motor side pinion 37 outputs the driving force of the electric motor 5, which is transmitted to the motor side intermediate shaft 31, to the differential mechanism 17.

[0025] The park lock gear portion 39 is disposed on the opposite side of the motor-side large-diameter gear portion 51 in the axial direction of the motor-side intermediate shaft 31, with the hub 53 in between. The park lock gear portion 39 is formed in an annular shape on the outer periphery of the motor-side intermediate shaft 31 by a single member that is continuous with the motor-side intermediate shaft 31. The park lock gear portion 39 is engageable with a lock member (not shown) of a parking lock mechanism (not shown). When engaged with the lock member, the park lock gear portion 39 prevents the motor-side intermediate shaft 31 from rotating, thereby preventing the vehicle from moving while parked.

[0026] The second transmission mechanism 13 is disposed on a power transmission path between the engine 7 and the generator 9 and the third transmission mechanism 15. The second transmission mechanism 13 includes a generator-side drive shaft 57 and a second gear set 61. The second gear set 61 is provided on a drive shaft 59 of the third transmission mechanism 15, which will be described later in this embodiment. Note that the drive shaft 59 of the third transmission mechanism 15, the high reduction clutch unit 63, and the low reduction clutch unit 65 will also be described below.

[0027] The generator-side drive shaft 57 is rotatably supported on the casing 3 via bearings 67, 69 on both axial ends thereof. The rotational axis of the generator-side drive shaft 57 is arranged concentrically with the rotational axis of the rotor 25 of the generator 9. One end of the generator-side drive shaft 57 is connected to the rotor 25 of the generator 9 via a connecting portion so as to be rotatable integrally therewith. The generator-side drive shaft 57 is rotated by the driving force from the engine 7, causing the rotor 25 of the generator 9 to rotate.

[0028] The outer periphery of the drive shaft 59 on both axial sides is rotatably supported by the casing 3 via bearings 71 and 73. The drive shaft 59 is arranged so that its rotation axis is parallel to the rotation axis of the generator side drive shaft 57.

[0029] The second gear set 61 is provided to be able to transmit power between the generator-side drive shaft 57 and the drive shaft 59, and has a generator gear portion 75 and a generator-side large-diameter gear portion 77. The generator gear portion 75 is formed as a single member continuous with the generator-side drive shaft 57 at the other end of the generator-side drive shaft 57. The generator-side large-diameter gear portion 77 is formed with a larger diameter than the generator gear portion 75 and meshes with the generator gear portion 75. The generator-side large-diameter gear portion 77 is formed separately from the drive shaft 59 and is connected to the outer periphery of the drive shaft 59 so as to be rotatable integrally with the drive shaft 59. The second gear set 61 transmits the driving force from the engine 7 from the drive shaft 59 to the generator-side drive shaft 57 at an increased speed.

[0030] The high reduction clutch portion 63 includes a high reduction gear portion 79 , a hub 81 , a disconnecting portion formed between the high reduction gear portion 79 and the hub 81 , and a sleeve 83 .

[0031] The high-reduction gear section 79 is formed separately from the drive shaft 59 and is disposed on the outer periphery of the drive shaft 59 via a bearing so as to be rotatable relative to the drive shaft 59. The hub 81 is disposed adjacent to the high-reduction gear section 79 in the axial direction of the drive shaft 59 and is formed as a single member that is continuous with the outer periphery of the drive shaft 59. The discontinuous section consists of a plurality of concave-convex engaging sections provided in the circumferential direction of the high-reduction gear section 79 and a connecting section that is splined on the outer periphery of the hub 81. The sleeve 83 is formed in an annular shape and is connected to the connecting section of the hub 81 so as to be movable in the axial direction relative to the connecting section of the hub 81 and to be rotatable integrally with the hub 81. A fork (not shown) of an actuator (not shown) engages with the outer periphery of the sleeve 83, and the sleeve 83 is moved axially.

[0032] The low speed clutch portion 65 includes a low speed gear portion 85 , a hub 81 , a discontinuous portion formed between the low speed gear portion 85 and the hub 81 , and a sleeve 83 .

[0033] The low-reduction gear section 85 has a larger diameter than the high-reduction gear section 79. The low-reduction gear section 85 is formed separately from the drive shaft 59, and is located on the opposite side of the hub 81 from the high-reduction gear section 79 in the axial direction of the drive shaft 59, and is disposed on the outer periphery of the drive shaft 59 via a bearing so as to be rotatable relative to the drive shaft 59. The intermittent section is made up of a plurality of concave-convex engaging sections provided in the circumferential direction of the low-reduction gear section 85, and a connecting section provided in a spline pattern on the outer periphery of the hub 81.

[0034] The high reduction clutch unit 63 and the low reduction clutch unit 65 are set to different reduction ratios and are engaged and disengaged depending on the running conditions of the vehicle when the engine 7 is used as the drive source.

[0035] For example, when the vehicle is traveling at low speeds, such as when starting, the sleeve 83 is moved axially toward the high reduction gear section 79, and the sleeve 83 is engaged with the engaging section of the high reduction gear section 79, bringing the intermittent section of the high reduction clutch section 63 into an engaged state. When the intermittent section of the high reduction clutch section 63 is engaged, the high reduction gear section 79 and the drive shaft 59 can rotate integrally, and the driving force from the engine 7 is transmitted to the high reduction gear section 79.

[0036] For example, when the vehicle is traveling stably at high speed, the sleeve 83 is moved axially toward the low-reduction gear unit 85, the sleeve 83 is engaged with the engaging portion of the low-reduction gear unit 85, and the intermittent portion of the low-reduction clutch unit 65 is brought into an engaged state. When the intermittent portion of the low-reduction clutch unit 65 is engaged, the low-reduction gear unit 85 and the drive shaft 59 can rotate integrally, and the driving force from the engine 7 is transmitted to the low-reduction gear unit 85.

[0037] For example, when the vehicle is traveling using only the driving force of the electric motor 5, the sleeve 83 is located in a neutral position at the hub 81. When the sleeve 83 is in the neutral position, the sleeve 83 is disengaged from the engaging portions of the high reduction gear unit 79 and the low reduction gear unit 85, and the engaging portions of the high reduction clutch unit 63 and the low reduction clutch unit 65 are in a disengaged state. When the engaging portions of the high reduction clutch unit 63 and the low reduction clutch unit 65 are in a disengaged state, the high reduction gear unit 79 and the low reduction gear unit 85 are able to rotate relative to the drive shaft 59, and power transmission between the engine 7 and the differential mechanism 17 is interrupted.

[0038] The third transmission mechanism 15 described in detail in this embodiment is disposed on a power transmission path between the engine 7 (second transmission mechanism 13) and the differential mechanism 17. The third transmission mechanism 15 includes a drive shaft 59, a high-speed reduction clutch unit 63, a low-speed reduction clutch unit 65, an intermediate shaft 87, a third gear set 89, and a pinion 91.

[0039] The outer periphery of the intermediate shaft 87 on both axial sides is rotatably supported by the casing 3 via bearings 93 and 95. The rotation axis of the intermediate shaft 87 is arranged parallel to the rotation axes of the generator side drive shaft 57 and the drive shaft 59.

[0040] The third gear set 89 includes a high reduction gear set 97 and a low reduction gear set 99 .

[0041] The high reduction gear set 97 is made up of a high reduction gear portion 79 and a large diameter gear portion 101 that is formed with a larger diameter than the high reduction gear portion 79 and meshes with the high reduction gear portion 79. The large diameter gear portion 101 is formed on the outer periphery of the intermediate shaft 87 as a single member that is continuous with the intermediate shaft 87. The high reduction gear set 97 transmits the driving force from the engine 7, which has been transmitted to the second transmission mechanism 13, to the intermediate shaft 87 at a speed ratio that results in high reduction.

[0042] The low-reduction gear set 99 is made up of the low-reduction gear section 85 and a small-diameter gear section 103 which is formed with a diameter larger than that of the low-reduction gear section 85 but smaller than that of the large-diameter gear section 101 and which meshes with the low-reduction gear section 85. The small-diameter gear section 103 is formed separately from the intermediate shaft 87 and is connected to the outer periphery of the intermediate shaft 87 so as to be rotatable integrally with the intermediate shaft 87. The high-reduction gear set 97 transmits the driving force from the engine 7, which has been transmitted to the second transmission mechanism 13, to the intermediate shaft 87 at a reduction ratio which results in low reduction.

[0043] By including the high reduction gear set 97 and the low reduction gear set 99 in the third gear set 89, the driving force transmitted from the engine 7 to the differential mechanism 17 can be selected according to the running conditions of the vehicle.

[0044] The pinion 91 is disposed between the large-diameter gear portion 101 and the small-diameter gear portion 103 in the axial direction of the intermediate shaft 87. The pinion 91 is formed separately from the intermediate shaft 87 and is coupled to the outer periphery of the intermediate shaft 87 so as to be rotatable integrally with the intermediate shaft 87. The pinion 91 outputs the driving force of the engine 7 transmitted to the intermediate shaft 87 to the differential mechanism 17.

[0045] The differential mechanism 17 is disposed on a power transmission path between the electric motor 5 (first transmission mechanism 11) and the engine 7 (third transmission mechanism 15) and the left and right drive wheels. The differential mechanism 17 includes a differential case 105, a pinion shaft 107, a pinion gear 109, and a pair of side gears 111 and 113.

[0046] The differential case 105 is rotatably supported on the casing 3 via a pair of bearings 119, 121 on the outer peripheries of bosses 115, 117 formed on both axial sides. The large-diameter gear portion 101 of the intermediate shaft 87 is disposed axially between the pair of bearings 119, 121. This allows the intermediate shaft 87 and the differential mechanism 17 to be disposed with a large radial overlapping portion, thereby reducing the portion that protrudes in the axial direction and enabling the axial size to be reduced.

[0047] The differential case 105 is formed with a flange portion 125 to which the ring gear 123 is fixed. The flange portion 125 is arranged so that at least a portion of the radial direction overlaps with the large diameter gear portion 101 and the small diameter gear portion 103 of the intermediate shaft 87 when viewed from the rotation axis direction. This allows the intermediate shaft 87 and the differential mechanism 17 to be arranged close to each other in the radial direction, thereby enabling the size to be reduced in the radial direction.

[0048] The ring gear 123 is in mesh with the motor-side pinion 37 of the first transmission mechanism 11 and the pinion 91 of the third transmission mechanism 15. The driving forces of the electric motor 5 and the engine 7 are input to the ring gear 123, which rotates and drives the differential case 105. The differential case 105 houses a pinion shaft 107, a pinion gear 109, and a pair of side gears 111, 113.

[0049] In this embodiment, pinion shaft 107 is a single long pinion shaft, but it may also be a combination of one long pinion shaft and two short pinion shafts. In the case of a long pinion shaft, both ends are engaged with holes formed in differential case 105 to prevent it from coming off, and it is rotated and driven integrally with differential case 105. In the case of a short pinion shaft, one end is engaged with a hole formed in the middle of the long pinion shaft, and the other end is engaged with holes formed in differential case 105 to prevent it from coming off, and it is rotated and driven integrally with differential case 105. Pinion gears 109 are supported on the outer end sides of pinion shaft 107.

[0050] One pinion gear 109 is disposed on each end of the pinion shaft 107. The multiple pinion gears 109 are supported on the end of the pinion shaft 107 and revolve with the rotation of the differential case 105. The pinion gears 109 are rotatably supported on the pinion shaft 107 so as to be rotationally driven when a differential rotation occurs between the pair of meshed side gears 111, 113. The pinion gears 109 transmit the driving force input to the differential case 105 to the pair of side gears 111, 113.

[0051] The pair of side gears 111, 113 are housed in a differential case 105 so as to be rotatable relative to one another. The pair of side gears 111, 113 are each meshed with a pinion gear 109. On the inner circumferential sides of the pair of side gears 111, 113, spline-shaped output portions 127, 129 are provided which output the driving force transmitted to the pair of side gears 111, 113. A pair of output shafts (not shown) which are connected to left and right drive wheels so as to be rotatable together are connected to the output portions 127, 129 so as to be rotatable together.

[0052] In the differential mechanism 17, driving force from the electric motor 5 and the engine 7 as driving sources is input to a differential case 105. The driving force input to the differential case 105 is transmitted to a pair of side gears 111, 113 via a pinion gear 109. The driving force transmitted to the pair of side gears 111, 113 is distributed and output to the left and right drive wheels.

[0053] Here, when the differential case 105 of the differential mechanism 17 rotates, the intermediate shaft 87 of the third transmission mechanism 15 is constantly rotating via the pinion 91 meshing with the ring gear 123. The intermediate shaft 87 is disposed below the motor-side drive shaft 29, the motor-side intermediate shaft 31, the generator-side drive shaft 57, the drive shaft 59, and the rotation axis of the differential case 105. Therefore, the intermediate shaft 87 is disposed at the lowest position among all the rotation axes disposed in parallel. By disposing the intermediate shaft 87 at the lowest position, the large-diameter gear portion 101 and the small-diameter gear portion 103 of the intermediate shaft 87 can constantly scoop up the lubricating oil contained in the casing 3, thereby improving lubrication.

[0054] The large diameter gear portion 101 of the intermediate shaft 87 is disposed closer to the dividing surface 19 of the casing 3 than the small diameter gear portion 103. As shown in FIG. 4, if the small diameter gear portion 103 is disposed closer to the dividing surface 19 than the large diameter gear portion 101, the large diameter gear portion 101 will be disposed closer to the bottom of the casing 3. This requires securing a space for disposing the large diameter gear portion 101 on the bottom of the casing 3, which increases the size of the casing 3. In contrast, as shown in FIG. 3, if the large diameter gear portion 101 is disposed closer to the dividing surface 19 than the small diameter gear portion 103, the small diameter gear portion 103 will be disposed closer to the bottom of the casing 3. This allows for a reduction in the space required for disposing the casing 3 on the bottom side, thereby enabling the casing 3 to be made more compact.

[0055] 2, the lower end of large diameter gear portion 101 is located vertically below the lower end of ring gear 123. Intermediate shaft 87 on which large diameter gear portion 101 is provided is disposed on the power transmission path between drive shaft 59 and differential mechanism 17. Therefore, large diameter gear portion 101 can constantly scoop up the lubricating oil contained in casing 3, thereby improving the lubrication of the meshing portions and sliding portions of the gears of drive shaft 59, intermediate shaft 87, and differential mechanism 17.

[0056] Such a power transmission device 1 includes a casing 3, a drive shaft 59 rotatably housed in the casing 3, and an intermediate shaft 87 rotatably housed in the casing 3 and capable of transmitting power between the drive shaft 59. The power transmission device 1 also includes a differential mechanism 17 that is rotatably housed in the casing 3 and has a differential case 105 that is capable of transmitting power between the intermediate shaft 87. The intermediate shaft 87 also has a small-diameter gear portion 103 and a large-diameter gear portion 101 that has a diameter larger than the small-diameter gear portion 103. The large-diameter gear portion 101 is disposed axially between a pair of bearings 119, 121 that rotatably support the differential case 105.

[0057] Therefore, the intermediate shaft 87 and the differential mechanism 17 can be arranged so that the overlapping portion in the radial direction is large, and the portion that protrudes in the axial direction can be reduced, thereby making the device more compact in the axial direction.

[0058] Therefore, such a power transmission device 1 can be made compact.

[0059] Moreover, the differential case 105 and the large diameter gear portion 101 are disposed so as to at least partially overlap each other when viewed from the front in the axial direction.

[0060] Therefore, the intermediate shaft 87 and the differential mechanism 17 can be disposed close to each other in the radial direction, and the size can be reduced in the radial direction.

[0061] The casing 3 is made up of a plurality of divided members divided by a dividing surface 19 that is perpendicular to the intermediate shaft 87. The large diameter gear portion 101 is disposed closer to the dividing surface 19 than the small diameter gear portion 103.

[0062] If the large diameter gear portion 101 is disposed closer to the dividing surface 19 than the small diameter gear portion 103, the small diameter gear portion 103 will be disposed on the bottom side of the casing 3. This allows the space required for disposing the casing 3 on the bottom side to be reduced, and the casing 3 can be made smaller.

[0063] Furthermore, the intermediate shaft 87 is disposed at the lowest position inside the casing 3.

[0064] The intermediate shaft 87, which is disposed on the power transmission path between the drive shaft 59 and the differential mechanism 17, is constantly rotating when rotation occurs in the differential mechanism 17. Therefore, by disposing the intermediate shaft 87 at the lowest position, the large diameter gear portion 101 and the small diameter gear portion 103 of the intermediate shaft 87 can constantly scoop up the lubricating oil contained in the casing 3, thereby improving lubrication.

[0065] A pinion 91 is provided on the intermediate shaft 87. A ring gear 123 that is meshed with the pinion 91 and is capable of transmitting power is provided on the differential case 105. The lower end of the large diameter gear portion 101 is located vertically below the lower end of the ring gear 123.

[0066] Therefore, the large diameter gear portion 101 can constantly scoop up the lubricating oil contained in the casing 3, improving the lubrication of the gear meshing and sliding parts between the drive shaft 59, intermediate shaft 87, and differential mechanism 17.

[0067] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

[0068] For example, in this embodiment, the third gear set is configured by a high reduction gear set and a low reduction gear set, but it may be configured with only a single reduction gear set.

[0069] Furthermore, although the third gear set has been described as a three-shaft reduction structure consisting of the second rotating shaft, the third rotating shaft, and the rotating shaft of the differential mechanism, it may also be a two-shaft reduction structure formed between the second rotating shaft and the rotating shaft of the differential mechanism. [Explanation of symbols]

[0070] 1 Power transmission device 3 Casing 17 Differential mechanism 19 Split plane 59 Drive shaft 87 Intermediate shaft 91 Pinion 101 Large diameter gear section 103 Small diameter gear section 119,121 Bearings 123 Ring Gear

Claims

1. A casing; a drive shaft rotatably housed in the casing; an intermediate shaft rotatably housed in the casing and capable of transmitting power between the intermediate shaft and the drive shaft; a differential mechanism having a differential case rotatably accommodated in the casing and capable of transmitting power between the differential mechanism and the intermediate shaft; Equipped with the intermediate shaft has a small diameter gear portion and a large diameter gear portion having a diameter larger than that of the small diameter gear portion, The large diameter gear portion is disposed axially between a pair of bearings that rotatably support the differential case.

2. The power transmission device according to claim 1 , wherein the differential case and the large diameter gear portion are disposed so as to at least partially overlap each other when viewed from the front in the axial direction.

3. the casing is made up of a plurality of divided members divided along dividing planes orthogonal to the intermediate shaft, 3. The power transmission device according to claim 1, wherein the large diameter gear portion is disposed closer to the dividing surface than the small diameter gear portion.

4. 3. The power transmission device according to claim 1, wherein the intermediate shaft is disposed at the lowest position inside the casing.

5. The intermediate shaft is provided with a pinion, The differential case is provided with a ring gear that meshes with the pinion and is capable of transmitting power, 3. The power transmission device according to claim 1, wherein a lower end of the large diameter gear portion is positioned vertically lower than a lower end of the ring gear.

Images