Unit

Abstract

To reduce an amount of oil lump entering a breather passage.SOLUTION: A unit includes: a hollow shaft configured as a rotary element; and a breather passage communicated to a hollow part of the hollow shaft. The hollow shaft includes a part configuring a discharge passage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a unit. [Background technology]

[0002] Patent Document 1 discloses a drive device for an electric vehicle in which a vent hole for a breather is arranged on the outer peripheral wall of a case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-82930 A Summary of the Invention [Problem to be solved by the invention]

[0004] When oil is dispersed or stirred by the rotation of a rotor, liquid or foamy oil may adhere to the inner surface of the outer wall of the case, etc. For this reason, in a unit having a breather passage, it is desirable that the liquid or foamy oil lumps generated by such an event do not pass through the breather passage.

[0005] The present invention has been made in view of the above problems, and has an object to reduce the amount of oil lumps that infiltrate into the breather passage. [Means for solving the problem]

[0006] A unit according to one aspect of the present invention has a hollow shaft configured as a rotating element, and a breather passage communicating with a hollow portion of the hollow shaft, the hollow shaft having a portion that constitutes a discharge passage. Effect of the Invention

[0007] According to this aspect, even if a lump of oil in a liquid or foam form adheres to the hollow portion inside the hollow shaft, the lump of oil is discharged through the drain passage before it reaches the breather passage. Therefore, the amount of the oil lump that infiltrates into the breather passage can be reduced. When the hollow shaft is rotating, centrifugal force promotes the discharge of oil from the drain passage, and when the hollow shaft is stopped, gravity promotes the discharge of oil from the drain passage. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a unit according to this embodiment. [Diagram 2] FIG. 2 is a diagram showing the speed reducing mechanism housed in the housing. [Diagram 3] FIG. 3 is a diagram showing the main part of the unit. [Figure 4] FIG. 4 is a diagram showing a main part of a unit according to a first modified example. [Diagram 5] FIG. 5 is a diagram showing a main part of a unit according to the second modified example. [Figure 6] FIG. 6 is a diagram showing a main part of a unit according to a third modified example. [Figure 7] FIG. 7 is a diagram showing a main part of a unit according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] 1 is a schematic diagram of a unit 100A according to this embodiment. With regard to the term "unit," the unit can also be called, for example, a motor unit (a unit having at least a motor) or a power transmission device (a device having at least a power transmission mechanism). The motor is a rotating electric machine having an electric motor function and / or a generator function (at least one of an electric motor function and a generator function). The power transmission mechanism is, for example, a gear mechanism and / or a differential gear mechanism. A device (unit) having a motor and a power transmission mechanism is included in the concepts of both a motor unit and a power transmission device.

[0011] The unit 100A includes a housing 10A, a reduction mechanism 20, and a differential gear 30. The unit 100A is mounted on a vehicle. The vehicle is an electric vehicle using a rotating electric machine 40 as a power source. The unit 100A transmits power from the rotating electric machine 40 to driving wheels. The unit 100A can also transmit power from the driving wheels to the rotating electric machine 40.

[0012] The housing 10A has a case 11A and a cover 12. Both the case 11A and the cover 12 are housing members, with the case 11A being provided on one axial side (the right side in FIG. 1) and the cover 12 being provided on the other axial side (the left side in FIG. 1). The axial direction is the extension direction of the shaft (power transmission shaft) of the unit 100A, and the extension directions of a first shaft 21, a second shaft 22A, and a third shaft 33, which will be described later, correspond to the axial direction. The case 11A and the cover 12 are joined by bolts or the like with their mating surfaces mated to each other to form the housing 10A.

[0013] The housing 10A has an accommodation chamber S. The accommodation chamber S is formed as a space surrounded by the case 11A and the cover 12, and the accommodation chamber S accommodates the reduction mechanism 20 and the differential gear 30.

[0014] The reduction gear mechanism 20 is a gear mechanism, and has a first shaft 21 and a second shaft 22A. The first shaft 21 is connected to the rotating electric machine 40. The first shaft 21 is connected to the rotating electric machine 40 so as to be capable of transmitting power, and is directly coupled to a rotating shaft 41 of the rotating electric machine 40 by, for example, a spline coupling. The connection may be via another configuration (for example, a clutch or another gear mechanism).

[0015] The rotating shaft 41 protrudes into the accommodation chamber S through a through hole 11a of the case 11A, and a sealant 60 is provided between the through hole 11a and the rotating shaft 41. The sealant 60 separates the inside and outside of the housing 10A at the through hole 11a. The unit 100A can also be understood as having a configuration further including a rotating electric machine 40.

[0016] The first shaft 21 has a first gear G1. The first gear G1 outputs power from the rotating electric machine 40. The first shaft 21 is supported by the case 11A via a bearing 51 on one axial side, and is supported by the cover 12 via a bearing 52 on the other axial side.

[0017] The second shaft 22A has a second gear G2 and a third gear G3. The third gear G3 is disposed closer to the rotating electric machine 40 than the second gear G2 (on the right side in FIG. 1). The second gear G2 meshes with the first gear G1, and power is input to the second gear G2 from the first gear G1.

[0018] The power input to the second gear G2 is output from the third gear G3. The second gear G2 and the first gear G1 configure a first reduction gear stage. The second shaft 22A is supported on one axial side by the case 11A via a bearing 53, and on the other axial side by the cover 12 via a bearing 54.

[0019] A breather passage 113A that suppresses an increase in the internal pressure of the accommodation chamber S is provided in the first fixed support portion 112A, which is a portion of the case 11A that supports the bearing 53. The second shaft 22A, the first fixed support portion 112A, and the breather passage 113A will be described in further detail below.

[0020] The differential gear 30 is a differential gear mechanism, and includes a differential case 31, a fourth gear G4 which is a final gear, and a differential portion 32. The differential case 31 is supported by the case 11A via a bearing 55, and is supported by the cover 12 via a bearing 56.

[0021] A fourth gear G4 is coaxially fixed to the outer wall of the differential case 31. The fourth gear G4 meshes with the third gear G3, and power is input from the third gear G3 to the fourth gear G4. The fourth gear G4 and the third gear G3 form a second reduction gear stage. Therefore, in the unit 100A, two-stage reduction is performed by the first gear G1 and the second gear G2, and the third gear G3 and the fourth gear G4.

[0022] The differential case 31 houses a differential unit 32, and the differential unit 32 distributes and outputs the power input to the differential case 31 via the fourth gear G4 to each of the drive wheels (not shown) in the left and right directions of the vehicle. The differential case 31 and the fourth gear G4 form a third shaft 33 of the unit 100A.

[0023] The unit 100A is a three-shaft power transmission device in which a total of three shafts, a first shaft 21, a second shaft 22A, and a third shaft 33, are arranged as power transmission shafts in the accommodation chamber S. The shafts of the unit 100A are composed of a plurality of shafts that are sequentially connected in the radial direction by meshing of gear portions with each other.

[0024] Fig. 2 is a diagram showing the reduction mechanism 20 accommodated in the accommodation chamber S. Fig. 2 shows the reduction mechanism 20 together with the oil reservoir 10a as viewed from the cover 12 side in the axial direction. In Fig. 2, the up-down direction of the figure corresponds to the direction of gravity, and the left-right direction of the figure corresponds to the front-rear direction of the vehicle.

[0025] As shown in FIG. 2, the housing 10A has an oil reservoir 10a. The oil reservoir 10a is provided at the bottom of the housing 10A. The oil in the oil reservoir 10a is used for upward circulation, and the oil that is scooped up falls due to the action of gravity after being used for lubrication, for example, and is stored again in the oil reservoir 10a. The fourth gear G4 is immersed in the oil reservoir 10a and scoops up the oil in the oil reservoir 10a. In FIG. 2, the oil level in the oil reservoir 10a is shown as the oil level when the unit 100A is operating.

[0026] The fourth gear G4 is provided at a height such that most of the lower half of the fourth gear G4 is immersed in the oil reservoir 10a when the unit 100A is operating. The fourth gear G4 is provided at a height such that at least a portion of the fourth gear G4 is immersed in the oil reservoir 10a whether the unit 100A is operating or stopped.

[0027] When the oil is stirred or stirred by the rotation of the fourth gear G4, which is a rotating body, an event may occur in which liquid or foamy oil adheres to the inner surface of the outer wall of the housing 10A. For this reason, in the unit 100A having the breather passage 113A, it is desirable that the liquid or foamy oil lumps generated by such an event do not pass through the breather passage 113A.

[0028] In light of these circumstances, the unit 100A is further configured as follows.

[0029] 3 is a diagram showing a main part of the unit 100A. The second shaft 22A is a hollow shaft and is open at both axial ends. The second shaft 22A has a first rotation support part 221A, a second rotation support part 222, and a hollow part 223. The second gear G2 is integrated with the second shaft 22A by press-fitting, and the third gear G3 is integrally formed with the second shaft 22A. The first rotation support part 221A and the second rotation support part 222 are provided on the second shaft 22A in a part extending from the second gear G2 and the third gear G3 on both axial sides.

[0030] The first rotation support portion 221A is provided at one end of the second shaft 22A. The first rotation support portion 221A is a rotation support portion that corresponds to the bearing 53, and configures a support portion that rotates as part of the second shaft 22A.

[0031] The first rotation support portion 221A has an open end 221a, a side wall portion 221bA, and an outer circumferential side cylindrical portion 221cA. The open end 221a is an open end on one end side of the second shaft 22A, and has an open end 221aa where the hollow portion 223 opens. The side wall portion 221bA extends in the radial direction from the open end 221aa. The side wall portion 221bA extends in the radial direction over the entire circumference from the open end 221aa, and also extends in the radial direction from the open end 221a including the open end 221aa. The outer circumferential side cylindrical portion 221cA is a cylindrical portion on the outer circumferential side of the bearing 53, and extends in the axial direction from the side wall portion 221bA. The outer circumferential side cylindrical portion 221cA extends from the outer circumferential portion of the side wall portion 221bA toward the bearing 53 along the axial direction.

[0032] A bearing 53 having an inner race (inner ring) 53a and an outer race (outer ring) 53b is disposed on the inner circumference of the outer circumferential cylindrical portion 221cA. The outer race 53b of the bearing 53 is supported from the outer circumferential side by the first rotation support portion 221A, whereby the bearing 53 is supported from the outer circumferential side by the second shaft 22A.

[0033] The tip of the outer circumferential cylindrical portion 221cA is spaced from the case 11A in the axial direction, and a space is formed between the tip of the outer circumferential cylindrical portion 221cA and the case 11A in the axial direction. The bearing 53 is disposed so as to be flush with the tip of the outer circumferential cylindrical portion 221cA. Therefore, the bearing 53 faces the accommodation chamber S in the axial direction.

[0034] The second rotation support part 222 is provided at the other end of the second shaft 22A. The second rotation support part 222 is a rotation support part corresponding to the bearing 54, and constitutes a support part that rotates as part of the second shaft 22A. The second rotation support part 222 is formed in a shaft shape, and a bearing 54 having an inner race 54a and an outer race 54b is disposed on the outer periphery of the second rotation support part 222. The inner race 54a of the bearing 54 is supported by the second rotation support part 222 from the inner peripheral side, whereby the bearing 54 is supported by the second shaft 22A from the inner peripheral side.

[0035] The hollow portion 223 passes through the second shaft 22A in the axial direction. The hollow portion 223 is provided at the rotation center of the second shaft 22A with the axis line AX2 (see FIG. 2) of the second shaft 22A as a common axis line.

[0036] Bearings 53 and 54 are bearings that support second shaft 22A and are, for example, ball bearings. A bearing other than a sealed bearing, that is, a bearing different from a sealed bearing, can be used for bearing 53. Bearing 54 may also be a bearing other than a sealed bearing. Second shaft 22A is supported by case 11A via bearing 53, and is supported by cover 12 via bearing 54.

[0037] The case 11A has a housing wall portion 111A, a first fixed support portion 112A, and a breather passage 113A, and constitutes a fixed element in the unit 100A. The housing wall portion 111A is a wall portion of the case 11A that divides the inside and outside of the housing 10A. The first fixed support portion 112A is a fixed support portion corresponding to the bearing 53, and constitutes a support portion fixed to the housing wall portion 111A. The first fixed support portion 112A protrudes in a shaft shape from the housing wall portion 111A along the axial direction to the accommodation chamber S, with the axis AX2 of the second shaft 22A as a common axis.

[0038] A bearing 53 is disposed on the outer periphery of the first fixed support portion 112A. An inner race 53a of the bearing 53 is supported from the inner periphery side by the first fixed support portion 112A, and thus the bearing 53 is supported from the inner periphery side by the case 11A.

[0039] The breather passage 113A is formed in the housing wall portion 111A and the first fixed support portion 112A. The breather passage 113A opens at the tip of the first fixed support portion 112A and extends from the tip of the first fixed support portion 112A along the axial direction into the first fixed support portion 112A and further into the housing wall portion 111A. The breather passage 113A further bends and extends upward within the housing wall portion 111A.

[0040] The breather passage 113A can also be understood to have the first fixed support portion 112A as an inner cylindrical portion extending axially toward the open end 221aa of the second shaft 22A. The inner cylindrical portion is a cylindrical portion on the inner side of the bearing 53, and the first fixed support portion 112A corresponds to the inner cylindrical portion.

[0041] The cover 12 has a housing wall portion 121 and a second fixed support portion 122. The housing wall portion 121 is a wall portion of the cover 12 that separates the inside from the outside of the housing 10A. The second fixed support portion 122 is a fixed support portion corresponding to the bearing 54, and constitutes a support portion fixed to the housing wall portion 121. The second fixed support portion 122 protrudes in a cylindrical shape from the housing wall portion 121 along the axial direction into the accommodation chamber S, with the axis AX2 of the second shaft 22A as a common axis.

[0042] The bearing 54 is disposed on the inner periphery of the second fixed support portion 122. An outer race 54b of the bearing 54 is supported from the outer periphery side by the second fixed support portion 122, whereby the bearing 54 is supported by the cover 12 from the outer periphery side.

[0043] The bearing 54 is disposed so as to be flush with the tip of the second fixed support part 122, and is disposed so as to be flush with the tip of the second rotation support part 222. The bearing 54 and the second shaft 22A are provided spaced apart from the housing wall part 121 in the axial direction, and a space is formed in the axial direction between the bearing 54 and the second shaft 22A and the cover 12. In this space, a partitioned space D is formed which is partitioned from the accommodation chamber S by the housing wall part 121, the second fixed support part 122, the bearing 54, and the second shaft 22A.

[0044] The second fixed support portion 122 has a through hole 122a. The through hole 122a communicates the partitioned space D with the storage chamber S. The through hole 122a is provided in a lower portion of the second fixed support portion 122 and opens downward into the storage chamber S.

[0045] The hollow portion 223 and the breather passage 113A provided in the first fixed support portion 112A are arranged side by side in the axial direction with the axis AX2 of the second shaft 22A as a common axis. The hollow portion 223 communicates with the breather passage 113A at one end and with the partitioned space D at the other end. The breather passage 113A communicates with the hollow portion 223 in a breathable manner. Therefore, when the internal pressure of the storage chamber S increases, air from the storage chamber S enters the partitioned space D and is then discharged through the hollow portion 223 to the breather passage 113A and further to the outside of the housing 10A, thereby suppressing the increase in internal pressure.

[0046] When oil is dispersed or stirred by the rotation of the fourth gear G4 (see FIG. 2), liquid or foamy oil may infiltrate from the storage chamber S into the compartmented space D. In the compartmented space D, for example, oil that has been stirred by the fourth gear G4 and turned into foam grows in the storage chamber S and reaches the through-hole 122a and further to the compartmented space D. Liquid or foamy oil also infiltrates into the compartmented space D due to a change in the attitude of the vehicle on which the unit 100A is mounted, etc. A portion of the liquid or foamy oil that has infiltrated into the compartmented space D may further infiltrate into the hollow portion 223 as a lump, or may form a lump in the hollow portion 223 and then pass through the breather passage 113A.

[0047] In consideration of these circumstances, the second shaft 22A further has a through hole 224. The through hole 224 is a discharge passage, and is provided in the second shaft 22A as a discharge passage that is responsible for discharging oil from the hollow portion 223. The second shaft 22A has a portion that constitutes a discharge passage by having the through hole 224. The through hole 224 discharges from the hollow portion 223 any lump of liquid or foamy oil that has entered the hollow portion 223, and as a result, the lump of liquid or foamy oil is discharged into the storage chamber S.

[0048] Therefore, even if a liquid or foamy lump of oil adheres to hollow portion 223 in second shaft 22A, the lump of oil is discharged through through hole 224 before reaching breather passage 113A, thereby reducing the amount of oil lump that infiltrates into breather passage 113A. When second shaft 22A is rotating, centrifugal force promotes oil discharge from through hole 224, and when second shaft 22A is stopped, gravity promotes oil discharge from through hole 224. Discharge of oil from through hole 224 is also promoted by the high temperature inside housing 10A when the vehicle is traveling at high speed.

[0049] The through hole 224 is formed in the second shaft 22A as a hole that opens in the radial direction. By forming the through hole 224 to have a shape that opens in the radial direction, oil discharge by centrifugal force is further promoted. The through hole 224 extends along the radial direction and opens in the radial direction on both the hollow portion 223 side and the storage chamber S side, so that the through hole 224 is formed as a through hole that connects these two openings in the radial direction. The through hole 224 is provided in the second shaft 22A in a portion between the first rotation support portion 221A and the second rotation support portion 222 in the axial direction, that is, in the middle portion of the second shaft 22A.

[0050] A plurality of through holes 224 are provided as a plurality of drain holes. By providing a plurality of through holes 224, the probability that oil will be discharged by gravity when the second shaft 22A is stopped is increased, so that a structure that promotes overall oil discharge can be achieved.

[0051] The plurality of through holes 224 is configured by, for example, two through holes 224 arranged radially (in other words, two through holes 224 arranged at 180 degree intervals in the circumferential direction). The plurality of through holes 224 can be arranged symmetrically with respect to the axis line AX2 (see FIG. 2) of the second shaft 22A. This can increase the probability that oil is discharged from the hollow portion 223 by gravity while the second shaft 22A is stopped, compared to a case in which the plurality of through holes 224 are arranged so that all of them can be located in an upper portion of the second shaft 22A depending on the rotational position of the second shaft 22A.

[0052] An axial clearance CL is provided between the tip of the first fixed support portion 112A of the case 11A and the open end 221aa of the second shaft 22A. The axial clearance CL is a clearance formed in the axial direction between the case 11A and the second shaft 22A, and the bearing 53 faces the accommodation chamber S on one axial side and faces the axial clearance CL on the other axial side. Therefore, the unit 100A is configured so that oil flows toward the bearing 53 through the axial clearance CL.

[0053] On the other hand, the second shaft 22A further has an open end 221aa that forms an axial clearance CL as a part that constitutes a discharge passage. The open end 221aa, together with the tip of the first fixed support part 112A that faces it in the axial direction, constitutes a discharge passage having an axial clearance CL width. The discharge passage having an axial clearance CL width, together with the through hole 224, constitutes a plurality of discharge passages provided in a parallel relationship with the hollow part 223.

[0054] For this reason, the oil is also supplied to the bearing 53 supporting the second shaft 22A through a discharge passage having a width of the axial clearance CL, and then is discharged into the accommodation chamber S. Therefore, the oil can be discharged from the hollow portion 223 through the bearing 53 into the accommodation chamber S, and the bearing 53 can also be lubricated with the discharged oil.

[0055] The bearing 53 is provided between the outer circumferential cylindrical portion 221cA and the first fixed support portion 112A serving as the inner circumferential cylindrical portion of the breather passage 113A. By arranging the bearing 53 in this manner, the bearing 53 supporting the second shaft 22A can be lubricated by a lump of oil discharged through the axial clearance CL provided between the opening end 221aa and the first fixed support portion 112A.

[0056] 1 and 2, the unit 100A has a plurality of gears, a first gear G1 to a fourth gear G4. As shown in Fig. 2, the axis AX2 of the second shaft 22A is set at a position higher than the axis AX1 of the first shaft 21 and the axis AX3 of the third shaft 33, and the positions of the plurality of gears are determined based on the axes. Therefore, the second shaft 22A is configured to rotate integrally with the second gear G2 and the third gear G3, which are arranged at the highest positions among the plurality of gears, the first gear G1 to the fourth gear G4.

[0057] As a result, the second shaft 22A having the hollow portion 223 is disposed at a position away from the oil reservoir 10a, so that oil scattered from the vicinity of the oil reservoir 10a is less likely to reach the second shaft 22A, and therefore the amount of oil entering the breather passage 113A can be reduced.

[0058] It should be noted that the unit 100A does not have to be a power transmission device having a three-shaft configuration, and the second shaft 22A does not necessarily have to be configured to rotate integrally with the gear that is located at the highest position among the multiple gears.

[0059] The unit 100A may be configured as follows.

[0060] 4 is a diagram showing a main part of a unit 100B according to a first modified example. In the following, the corresponding configuration in the modified example is shown with a different reference numeral, such as unit 100B. The unit 100B is different from the unit 100A in that the second shaft 22B does not have a through hole 224, unlike the second shaft 22A. In the unit 100B, the second shaft 22B also has an open end 221aa as a part constituting a discharge passage, so that even if a lump of oil in a liquid or foam form adheres to the hollow portion 223 in the second shaft 22B, the lump of oil can be discharged through a discharge passage having an axial clearance CL width before the lump of oil reaches the breather passage 113A.

[0061] FIG. 5 is a diagram showing a main part of a unit 100C according to a second modified example. The unit 100C is different from the unit 100B shown in FIG. 4 in that the second shaft 22C further has a through hole 225 compared to the second shaft 22B. The same modification can be applied to the unit 100A. The through hole 225 is a discharge passage, and is formed in the second shaft 22C as a hole that opens in the axial direction. The through hole 225 is provided in the side wall portion 221bB of the first rotation support portion 221B. The through hole 225 is disposed at a position facing the bearing 53 in the axial direction, such as the outer race 53b. The through hole 225 passes through the side wall portion 221bB in the axial direction, thereby communicating the accommodation chamber S with the axial clearance CL. Similar to the through hole 224, a plurality of the through holes 225 can be provided as a plurality of discharge holes. In the unit 100C as well, the oil lump can be discharged via the through hole 225 before the oil lump reaches the breather passage 113A.

[0062] FIG. 6 is a diagram showing a main part of a unit 100D according to a third modified example. The unit 100D is different from the unit 100B shown in FIG. 4 in that the second shaft 22D further has a through hole 226 compared to the second shaft 22B. The same modification can be applied to the unit 100A and the unit 100C. The through hole 226 is a discharge passage, and is formed in the second shaft 22D as a hole that opens in the radial direction. The through hole 226 is provided in the outer circumferential cylindrical portion 221cB of the first rotation support portion 221C. The through hole 226 is disposed at a position facing the axial clearance CL along the radial direction. The through hole 226 penetrates the outer circumferential cylindrical portion 221cB along the radial direction, thereby communicating the storage chamber S with the axial clearance CL. Similar to the through hole 224, a plurality of the through holes 226 can be provided as a plurality of discharge holes. In the unit 100D, too, before the oil lumps reach the breather passage 113A, the oil lumps can be discharged via the through hole 226. Furthermore, since the through hole 226, which is a hole that opens in the radial direction, is located radially outward of the through hole 224, the oil discharge due to centrifugal force can be promoted as compared to the through hole 224.

[0063] Fig. 7 is a diagram showing a main part of a unit 100E according to a fourth modified example. The unit 100E differs from the unit 100A shown in Fig. 3 in that the bearing 53 is supported from the outer periphery by the case 11B of the housing 10B and from the inner periphery by the second shaft 22E. Therefore, in this modified example, the first fixed support part 112B is formed in a cylindrical shape like the second fixed support part 122, and supports the bearing 53 from the outer periphery. Also, the first rotation support part 221D is formed in a shaft shape like the second rotation support part 222, and supports the bearing 53 from the inner periphery.

[0064] The first rotation support 221D is located in the first fixed support 112B. The bearing 53 is provided so as to be flush with the open end 221aa of the second shaft 22E on one axial side, and is provided so as to be flush with the tip of the first fixed support 112B on the other axial side. The breather passage 113B is provided in the housing wall 111B and the first fixed support 112B. The breather passage 113B in the portion provided in the first fixed support 112B extends into the housing wall 111B along the axial direction, and then bends and extends upward. The breather passage 113B faces the second shaft 22E and the bearing 53 in the first fixed support 112B, and no axial clearance CL is formed.

[0065] In the unit 100E as well, the second shaft 22E has the through hole 224, and thus has a portion that constitutes a discharge passage, so that the oil lump can be discharged via the through hole 224 before it reaches the breather passage 113B.

[0066] Next, the main effects of this embodiment will be described.

[0067] (1) The units 100A to 100E each have a second shaft 22A to 22E which is a hollow shaft configured as a rotating element, and a breather passage 113A or 113B which communicates with a hollow portion 223 of the second shaft 22A to 22E. The second shafts 22A to 22E each have at least one of a through hole 224, an open end 221aa, a through hole 225, and a through hole 226 which serve as a portion configuring a discharge passage.

[0068] With this configuration, even if a liquid or foamy oil lump adheres to the hollow portion 223 in the second shaft 22A to 22E, which is a hollow shaft, the oil lump is discharged through the discharge passage before reaching the breather passage 113A or 113B. This makes it possible to reduce the amount of oil lump that infiltrates into the breather passage 113A or 113B. When the second shafts 22A to 22E are rotating, centrifugal force promotes the discharge of oil from the discharge passage, and when the second shafts 22A to 22E are stopped, gravity promotes the discharge of oil from the discharge passage.

[0069] (2) In the units 100A, 100D, and 100E, the through holes 224 and 226 serving as discharge passages are formed in the second shafts 22A, 22D, and 22E as holes that open in the radial direction. With this configuration, it is possible to form the discharge passages using holes that open in the axial direction, but by using holes that open in the radial direction, the discharge of oil by centrifugal force is further promoted.

[0070] (3) In the units 100A to 100D, the oil is supplied to the bearings 53 supporting the second shafts 22A to 22D through a discharge passage having an axial clearance CL width formed by the open end 221aa. This configuration is preferable because the discharged oil can lubricate the bearings 53.

[0071] (4) In the units 100A and 100E, the through holes 224 serving as discharge passages are provided in a plurality of positions as a plurality of discharge holes.

[0072] According to this configuration, when the second shafts 22A, 22E are stopped, the probability that the oil will be discharged by gravity is increased by providing a plurality of discharge passages, so that a structure that promotes overall oil discharge can be achieved. Note that the through hole 225 in the unit 100C and the through hole 226 in the unit 100D may also be provided in a plurality of places as a plurality of discharge holes.

[0073] (5) In the units 100A to 100D, the second shafts 22A to 22D have an open end 221aa, a side wall portion 221bA or 221bB extending radially from the open end 221aa, and an outer circumferential cylindrical portion 221cA or 221cB extending axially from the side wall portion 221bA or 221bB. The breather passage 113A has a first fixed support portion 112A as an inner circumferential cylindrical portion extending axially from the open end 221aa of the second shafts 22A to 22D. The bearing 53 is provided between the outer circumferential cylindrical portion 221cA or 221cB and the first fixed support portion 112A.

[0074] According to this configuration, the bearings 53 supporting the second shafts 22A to 22D can be lubricated by a lump of oil discharged through the axial clearance CL provided between the opening end 221aa and the first fixed support portion 112A, which serves as the inner cylindrical portion of the breather passage 113A.

[0075] (6) The units 100A to 100E each have a first gear G1 to a fourth gear G4 as multiple gears. The second shafts 22A to 22E are configured to rotate integrally with the second gear G2 and the third gear G3, which are located at the highest positions among the first gear G1 to the fourth gear G4.

[0076] With this configuration, the second shafts 22A to 22E can be arranged at a higher position in the direction of gravity, away from the oil reservoir 10a located below in the direction of gravity. As a result, oil scattered from near the oil reservoir 10a is less likely to reach the second shafts 22A to 22E, and the amount of oil entering the breather passage 113A or 113B can be reduced.

[0077] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0078] 11: Case 112A: First fixed support part (inner peripheral side cylindrical part) 113A, 113B: Breather passage 22A, 22B, 22C, 22D, 22E: Second shaft (hollow shaft) 221aa: Open end 221bA, 221bB: Side wall part 221cA, 221cB: Outer cylindrical part 223: Hollow part 224: Through hole (discharge passage, discharge hole) 225: Through hole (exhaust passage, exhaust hole) 226: Through hole (exhaust passage, exhaust hole) 53: Bearing 100A, 100B, 100C, 100D, 100E: Unit CL: Axial clearance (clearance) G1: 1st gear G2: 2nd gear G3: 3rd gear G4: 4th gear

Claims

1. A hollow shaft configured as a rotating element; a breather passage communicating with the hollow portion of the hollow shaft; The hollow shaft has a portion that defines a discharge passage. unit.

2. 2. The unit of claim 1, The discharge passage is formed in the hollow shaft as a hole opening in a radial direction. unit.

3. 2. The unit of claim 1, Oil is supplied to a bearing supporting the hollow shaft through the discharge passage. unit.

4. 2. The unit of claim 1, The discharge passage is provided as a plurality of discharge holes. unit.

5. 2. The unit of claim 1, the hollow shaft has an open end, a side wall portion extending radially from the open end, and an outer circumferential cylindrical portion extending axially from the side wall portion, the breather passage has an inner circumferential cylindrical portion extending axially toward the open end of the hollow shaft, A bearing is provided between the outer circumferential cylindrical portion and the inner circumferential cylindrical portion. unit.

6. A unit according to any one of claims 1 to 5, It has multiple gears, The hollow shaft is configured to rotate integrally with the gear that is located at the highest position among the plurality of gears. unit.

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