Differential device

Abstract

To provide a differential arrangement which can inhibit wear between an end washer and a side gear or a differential case.SOLUTION: A differential arrangement includes: a differential case 2; a pinion gear rotatably supported by the differential case 2; a pair of side gears which engages with the pinion gear and may rotate relative to the differential case 2; and an end washer 5 which is disposed between at least one of the pair of side gears and the differential case 2. The end washer 5 is formed with outer periphery slits 51 which penetrate through the end washer 5 in an axial direction and in each of which the outer periphery side of the end washer 5 is open.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a differential device.

Background Art

[0002] Patent Document 1 discloses a vehicle differential device that distributes the driving force of a vehicle while allowing differential between the left and right drive wheels. The vehicle differential device described in Patent Document 1 includes a differential case, a pair of pinion gears rotatably supported by the differential case, a pair of side gears respectively meshed with the pair of pinion gears and respectively connected to the pair of rear wheels, and a pair of end washers (i.e., the washers described in Patent Document 1) disposed between each of the pair of side gears and the differential case. [[ID=1十三]]

[0003] In the vehicle differential device described in Patent Document 1, when the vehicle is going straight, the pair of pinion gears revolve together with the differential case but do not rotate on their own, and the pair of side gears rotate at the same rotational speed as the differential case. On the other hand, when the vehicle is turning, the pair of pinion gears revolve and rotate on their own together with the differential case, and a rotational difference occurs between the side gears and the differential case. Therefore, when the vehicle is turning, friction may occur between the end washer and the side gear or the differential case.

[0004] Therefore, in the vehicle differential device described in Patent Document 1, a round hole (i.e., the through hole described in Patent Document 1) is formed in the end washer, and lubricating oil is configured to be supplied to both surfaces of the end washer through the round hole.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Even with a configuration that supplies lubricating oil to both sides of the end washer, such as the vehicle differential described in Patent Document 1, it is virtually impossible to completely eliminate friction between the end washer and the side gear or differential case. When friction occurs between the end washer and the side gear or differential case, wear particles can be generated from these sliding surfaces. These wear particles are collected in the circular holes formed in the end washer as it rotates relative to the side gear or differential case.

[0007] In the vehicle differential described in Patent Document 1, since only a circular hole is formed in the end washer, the generated wear particles accumulate concentratedly in the circular hole. If too much wear particles accumulate concentratedly in the circular hole, they may not be able to fit inside the hole, which could accelerate wear between the end washer and the side gear or differential case.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a differential that can suppress wear between the end washer and the side gear or differential case. [Means for solving the problem]

[0009] To achieve the above objective, the present invention comprises a differential case, a pinion gear rotatably supported in the differential case, a pair of side gears that mesh with the pinion gear and are rotatable relative to the differential case, and an end washer disposed between at least one of the pair of side gears and the differential case, wherein the end washer has an outer peripheral slit that penetrates axially and is open on the outer peripheral side. The inner circumferential surface of the end washer has an inner circumferential surface formed in a circular shape, the outer circumferential surface of the end washer has an outer circumferential surface formed in a circular shape, and the outer circumferential slit is formed to the inner side beyond the midpoint between the inner circumferential surface and the outer circumferential surface in the radial direction of the end washer. A differential device is provided. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a differential that can suppress wear between the end washer and the side gear or differential case. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing the overall configuration of the differential in the first embodiment. [Figure 2] This is a cross-sectional view taken along the line II-II in Figure 1. [Figure 3] This is an exploded perspective view of the components housed within the differential case in the first embodiment. [Figure 4] This is an enlarged perspective view of the bottom and end washers in the first embodiment. [Figure 5] This is a plan view of the bottom in the first embodiment. [Figure 6] This is a plan view of the end washer in the first embodiment. [Figure 7] This is a cross-sectional view of the bottom and end washer in the first embodiment, showing the state before the wear debris mass is cut. [Figure 8] This is a cross-sectional view of the bottom and end washer showing the state after the wear debris mass has been cut in the first embodiment. [Figure 9] This is a cross-sectional view showing the overall configuration of the differential in the second embodiment. [Figure 10] This is a cross-sectional view showing the overall configuration of the differential in the third embodiment. [Modes for carrying out the invention]

[0012] [First Embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 8. The embodiments described below are presented as preferred specific examples for carrying out the present invention, and while some parts specifically illustrate various technically preferable technical matters, the technical scope of the present invention is not limited to these specific embodiments.

[0013] (differential device) Figure 1 is a cross-sectional view showing the overall configuration of the differential 1 of this embodiment. Figure 2 is a cross-sectional view taken along the line II-II in Figure 1. Figure 3 is an exploded perspective view of the components housed within the differential case 2.

[0014] As shown in FIG. 1, the differential device 1 of the present embodiment is used to distribute the driving force of the vehicle drive source to a pair of output shafts 11 while allowing differential. The drive source is, for example, an engine or an electric motor, and the pair of output shafts 11 are, for example, the left and right drive shafts. The differential device 1 is arranged in an oil bath such that a part of the differential case 2 is immersed in the lubricating oil enclosed in a transmission case (not shown).

[0015] The differential device 1 of the present embodiment is a so-called LSD (Limited Slip Differential) that limits the differential of the driving force distributed to the pair of output shafts 11. The differential device 1 includes a differential case 2 to which the driving force is input, and five sets of pinion gear sets 3, a pair of side gears 4, a pair of end washers 5, and a center washer 6 housed in the differential case 2. As shown in FIGS. 2 and 3, the pinion gear set 3 is formed by meshing a first pinion gear 31 and a second pinion gear 32 with each other. As shown in FIG. 1, one side gear 4 is non-rotatably connected to one output shaft 11 and meshes with the first pinion gear 31, and the other side gear 4 is non-rotatably connected to the other output shaft 11 and meshes with the second pinion gear 32. The pair of end washers 5 are arranged between the differential case 2 and each of the pair of side gears 4. The center washer 6 is arranged between the pair of side gears 4.

[0016] A ring gear 12 is fixed to the differential case 2 using a plurality of bolts B1. The differential case 2 rotates about the rotation axis X by the driving force of the drive source input from the ring gear 12. Hereinafter, the direction parallel to the rotation axis X is referred to as the "axial direction", the rotation direction of the differential case 2 about the rotation axis X is referred to as the "circumferential direction", and the radial direction of the differential case 2 about the rotation axis X is simply referred to as the "radial direction". Also, the side on the center washer 6 side in the axial direction is referred to as the "inner side in the axial direction", and the opposite side is referred to as the "outer side in the axial direction". Also, the side on the rotation axis X side in the radial direction is referred to as the "inner circumferential side", and the opposite side is referred to as the "outer circumferential side".

[0017] The differential case 2 has a differential case main body 21 and a differential case cover 22. Each of the differential case main body 21 and the differential case cover 22 has an annular plate-shaped bottom portion 23 having a thickness in the axial direction, a cylindrical extending portion 24 extending axially outward from the inner peripheral portion of the bottom portion 23, a cylindrical side portion 25 extending axially inward from the outer peripheral portion of the bottom portion 23, and an annular plate-shaped flange portion 26 formed to spread outward from the end portion of the side portion 25 opposite to the bottom portion 23. The side portion 25 of the differential case main body 21 is formed to be longer in the axial direction than the side portion 25 of the differential case cover 22. The differential case main body 21 and the differential case cover 22 are overlapped with each other at the flange portion 26 and fastened to each other using bolts B2.

[0018] One output shaft 11 is inserted into the extending portion 24 of the differential case main body 21, and the other output shaft 11 is inserted into the extending portion 24 of the differential case cover 22. Further, a spiral groove 241 is formed on the inner peripheral surface of the extending portion 24. One end of the spiral groove 241 communicates with the outside of the differential case 2, and the other end of the spiral groove 241 is open to the internal space of the differential case 2. The lubricating oil in a transmission case not shown is rotated along with the rotation of the output shaft 11, introduced into the differential case 2 through the spiral groove 241, and used for lubricating the surface of the end washer 5 and the like.

[0019] As shown in FIG. 2, the same number of bores 27 as the number of sets of pinion gear sets 3 (that is, five sets in this embodiment) are formed in the outer peripheral region in the inner space of the differential case 2. The bore 27 is a cavity for arranging the pinion gear set 3, and different pinion gear sets 3 are arranged in the five bores 27. The five bores 27 are formed at equal intervals in the circumferential direction.

[0020] The bore 27 is defined by a first concave surface 251 and a second concave surface 252 formed on the inner surface of the side portion 25 of the differential case body 21. Each of the first concave surface 251 and the second concave surface 252 is formed such that a part of the inner circumferential surface of the side portion 25 is recessed toward the outer circumferential side, and the cross section perpendicular to the axial direction is formed to be arc-shaped. The first concave surface 251 is the surface that defines the space for the arrangement of the first pinion gear 31, and the second concave surface 252 is the surface that defines the space for the arrangement of the second pinion gear 32. The first pinion gear 31 slides in the first concave surface 251, and the second pinion gear 32 slides in the second concave surface 252.

[0021] Lubrication oil supply holes 253 are formed in the side portion 25 of the differential case body 21 between adjacent bores 27 in the circumferential direction. The lubrication oil supply holes 253 are formed to penetrate radially through the side portion 25 of the differential case body 21. When the vehicle moves forward, etc., the differential case 2 rotates relative to the transmission case, causing the lubrication oil in the transmission case to be drawn into the differential case 2 through the lubrication oil supply holes 253.

[0022] Figure 4 is an enlarged perspective view of the bottom portion 23 and the end washer 5. Figure 5 is a plan view of the bottom portion 23. As shown in Figures 1, 4, and 5, the bottom portion 23 has a recessed surface 231 for positioning the axial end of the pinion gear assembly 3. The bottom portion 23 also has a through hole 232 that opens into the recessed surface 231. The through hole 232 serves to introduce lubricating oil from the transmission case into the differential case 2 and to discharge excess lubricating oil introduced into the differential case 2. When the pinion gear assembly 3 is positioned in the bore 27, the through hole 232 communicates with the space surrounding the pinion gear assembly 3 within the bore 27.

[0023] As shown in Figures 1 and 3, the first pinion gear 31 integrally comprises a cylindrical shaft portion 311, a long gear portion 312 provided at one end of the shaft portion 311, and a short gear portion 313 provided at the other end of the shaft portion 311. The second pinion gear 32 integrally comprises a cylindrical shaft portion 321, a long gear portion 322 provided at one end of the shaft portion 321, and a short gear portion 323 provided at the other end of the shaft portion 321. The axial lengths of the long gear portions 312 and 322 are longer than the axial lengths of the short gear portions 313 and 323. The long gear portion 312 of the first pinion gear 31 meshes with the short gear portion 323 of the second pinion gear 32, and the short gear portion 313 of the first pinion gear 31 meshes with the long gear portion 322 of the second pinion gear 32.

[0024] When the vehicle is moving straight, the first pinion gear 31 and the second pinion gear 32 revolve around the differential case 2, but do not rotate on their own. As a result, when the vehicle is moving straight, each of the pair of side gears 4 rotates at the same speed as the differential case 2. On the other hand, when the vehicle is turning, the first pinion gear 31 and the second pinion gear 32 revolve around the differential case 2 and rotate on their own within the bore 27. As a result, when the vehicle is turning, the pair of side gears 4 rotate differentially, and the differential case 2 and each side gear 4 rotate relative to each other. Therefore, friction may occur between the differential case 2 and each side gear 4 when the vehicle is turning.

[0025] A pair of side gears 4 are aligned axially via a center washer 6. Each side gear 4 has a gear portion 41 on its outer circumference. The gear portion 41 of one side gear 4 meshes with the long gear portion 312 of the first pinion gear 31, and the gear portion 41 of the other side gear 4 meshes with the long gear portion 322 of the second pinion gear 32. The side gears 4 are provided with spline fitting holes 42 that penetrate axially. One output shaft 11 is connected to the spline fitting hole 42 of one side gear 4 in a manner that prevents relative rotation, and the other output shaft 11 is connected to the spline fitting hole 42 of the other side gear 4 in a manner that prevents relative rotation.

[0026] The first pinion gear 31, the second pinion gear 32, and the pair of side gears 4 are helical gears. Specifically, the long gear portion 312 and short gear portion 313 of the first pinion gear 31, the long gear portion 322 and short gear portion 323 of the second pinion gear 32, and the gear portion 41 of the side gear 4 are formed by helical teeth. When a driving force is input to the differential case 2 and this driving force is output from the pair of side gears 4 via the five sets of pinion gears 3, an axial thrust force acts on the first pinion gear 31, the second pinion gear 32, and the pair of side gears 4. In this embodiment, the twist angles of each gear portion are set so that a thrust force acts on the pair of side gears 4 in a direction that moves them closer together when the vehicle is moving forward or when it is driving at a constant speed, and a thrust force acts on the pair of side gears 4 in a direction that moves them apart when decelerating by engine braking. However, the torsional angle of each gear section may be set such that the pair of side gears 4 receive a thrust force in a direction that separates them from each other during acceleration or steady-state driving when the vehicle is moving forward.

[0027] As a result of the aforementioned thrust force, the frictional force between the side gear 4 and the end washer 5, or between the pair of side gears 4 and the center washer 6, increases. These frictional forces act as differential limiting forces, restricting the differential movement between the pair of side gears 4.

[0028] The side gear 4 faces outward in the axial direction and has an annular washer-facing surface 43. The washer-facing surface 43 is the surface that faces the end washer 5 in the axial direction, and the end washer 5 is positioned to overlap with the side gear 43 in the axial direction. The washer-facing surface 43 may be LAP-processed to reduce friction with the end washer 5.

[0029] Figure 6 is a plan view of the end washer 5. The end washer 5 has an annular shape. The end washer 5 has three outer circumferential slits 51 and three inner circumferential slits 52. The outer circumferential slits 51 are formed to penetrate the end washer 5 in the axial direction and are open on the outer side. The inner circumferential slits 52 are formed to penetrate the end washer 5 in the axial direction and are open on the inner side. The outer circumferential slits 51 and inner circumferential slits 52 are formed alternately and at equal intervals in the circumferential direction. The parts of the inner surface of the end washer 5 other than the parts where the inner circumferential slits 52 are formed are inner circumferential surfaces 53 that are formed in a circular shape. That is, when viewed from the axial direction, the inner circumferential surfaces 53 are formed to follow a first virtual circle (not shown). The parts of the outer surface of the end washer 5 other than the parts where the outer circumferential slits 51 are formed are outer circumferential surfaces 54 that are formed in a circular shape. In other words, when viewed from the axial direction, the outer circumferential surface 54 is formed to follow a second virtual circle (not shown).

[0030] The outer peripheral slit 51 is formed such that its width in the circumferential direction increases towards the outer circumference. In this embodiment, the outer peripheral slit 51 is formed in a substantially V-shape. The outer peripheral surface of the end washer 5, which consists of the outer peripheral circumferential surface 54 of the outer peripheral slit 51 and the inner surface of the outer peripheral slit 51, is formed smoothly so as to have no corners. For example, the portion 55 between the inner surface of the outer peripheral slit 51 and the outer peripheral circumferential surface 54 is formed in a curved (rounded) shape. This makes it easier for wear particles, which will be described later, to be discharged from the outer peripheral slit 51. Furthermore, the outer peripheral slit 51 is formed to the inner side of the central position C between the inner peripheral circumferential surface 53 and the outer peripheral circumferential surface 54 in the radial direction of the end washer 5. It is preferable from the viewpoint of ensuring the rigidity of the end washer 5 that the outer peripheral slit 51 is located on the outer peripheral side of the central position C1 between the inner peripheral circumferential surface 53 and the central position C in the radial direction.

[0031] The inner circumferential slit 52 is formed such that its width in the circumferential direction increases towards the inner circumference. In this embodiment, the inner circumferential slit 52 is formed in a substantially V-shape. The inner circumferential surface of the end washer 5, which consists of the inner circumferential surface 53 of the inner circumferential slit 52 and the inner surface of the inner circumferential slit 52, is formed smoothly so as to have no corners. For example, the portion 56 between the inner surface of the inner circumferential slit 52 and the inner circumferential surface 53 is formed in a curved (rounded) shape. Furthermore, the inner circumferential slit 52 extends to the outer circumference beyond the central position C in the radial direction of the end washer 5. As a result, in this embodiment, the inner circumferential slit 52 and the outer circumferential slit 51 are formed in a position where parts of each overlap in the circumferential direction. It is preferable from the viewpoint of ensuring the rigidity of the end washer 5 that the inner circumferential slit 52 is located on the inner circumference side of the central position C2 between the outer circumferential surface 54 and the central position C in the radial direction.

[0032] In this specification, a through-hole formed in the end washer 5, such as the inner circumferential slit 52, which is closed on the outer circumference side, is referred to as a washer through-hole. In other words, the inner circumferential slit 52 is a type of washer through-hole. In this embodiment, the washer through-hole is an inner circumferential slit 52 with an open inner circumference side, but it may also be a hole that is enclosed all around, such as a circular hole.

[0033] At least the axially inner surface of the end washer 5 is treated to enhance lubricity. In this embodiment, the axially inner surface of the end washer 5 is defric-coated with a lubricant containing a fluororesin such as polytetrafluoroethylene (PTFE). Alternatively, the axially inner surface of the end washer 5 may be defric-coated with a lubricant containing molybdenum disulfide or graphite. Furthermore, the axially inner surface of the end washer 5 may be further enhanced in lubricity by heat treatment such as nitriding. This prevents excessive friction between the end washer 5 and the side gear 4. The aforementioned surface treatment may also be applied to both sides of the end washer 5.

[0034] The outer circumferential slit 51 and the inner circumferential slit 52 collect wear particles generated by friction between the side gear 4 and the end washer 5, or between the end washer 5 and the differential case 2, when the side gear 4 and the differential case 2 rotate relative to each other. In this embodiment, when the surface of the end washer 5 is coated with fluororesin, the wear particles consist of fragments of fluororesin. Since the outer circumferential slit 51 is open on the outer circumference side, the wear particles collected in the outer circumferential slit 51 are discharged directly to the outer circumference side. Wear particles collected in the inner circumferential slit 52 are discharged from the inner circumferential slit 52 to the inner circumference side and can then be discharged through the lubrication groove 233c. Furthermore, when the position of the inner circumferential slit 52 in the circumferential direction coincides with the position of the lubrication groove 233c described later, the wear particles collected in the inner circumferential slit 52 are discharged through the lubrication groove 233c.

[0035] As shown in Figure 1, one end washer 5 is fitted into a fitting recess 233 formed in the bottom 23 of the differential case body 21, and the other end washer 5 is fitted into a fitting recess 233 formed in the bottom 23 of the differential case cover 22. In this embodiment, an example is described in which the fitting recess 233 of the differential case body 21 and the fitting recess 233 of the differential case cover 22 have similar shapes, but they may have different shapes. The end washer 5 is not fixed to the fitting recess 233 and is rotatable relative to both the differential case 2 and the side washer. Therefore, when the vehicle turns, the differential case 2, the side gear 4 and the end washer 5 can rotate relative to each other, which can cause friction between the end washer 5 and the differential case 2 and the side gear 4.

[0036] As shown in Figures 1, 4, and 5, the fitting recess 233 is an annular recess that opens axially inward and on the inner circumference. The fitting recess 233 has an annular opposing portion 233a that faces the end washer 5 in the axial direction, and a plurality of protrusions 233b that project axially inward from the outer circumference end of the opposing portion 233a.

[0037] Furthermore, five lubrication grooves 233c are formed in the fitting recess 233, extending in a direction perpendicular to the axial direction. The number of lubrication grooves 233c formed in the fitting recess 233 is different from the number of outer peripheral slits 51 of the end washer 5 placed in the fitting recess 233, and is also different from both the divisors and multiples of the number of outer peripheral slits 51. In this embodiment, the number of lubrication grooves 233c formed in the fitting recess 233 is different from the total number of outer peripheral slits 51 and inner peripheral slits 52 of the end washer 5 placed in the fitting recess 233, and is also different from both the divisors and multiples of the total number of outer peripheral slits 51 and inner peripheral slits 52. The five lubrication grooves 233c are positioned at equal intervals in the circumferential direction.

[0038] Each lubrication groove 233c is a groove with a substantially arc-shaped cross-section, and is formed such that the axially inner surface of the opposing portion 233a is recessed axially outward. Furthermore, each lubrication groove 233c is formed to pass between adjacent protrusions 233b in the circumferential direction. Each lubrication groove 233c is formed with an inclination toward one side in the circumferential direction as it approaches the outer circumference. Each lubrication groove 233c may be formed radially, for example, or may have a curved shape. The outer circumferential end of each lubrication groove 233c communicates with the outside of the differential case 2 via the bore 27 and the through hole 232. Each lubrication groove 233c may also communicate with the outside of the differential case 2 via a path other than the bore 27. The lubrication groove 233c facilitates the flow of lubricating oil from the extended portion 24 into the differential case 2, from the inner circumference to the outer circumference, in a direction perpendicular to the axial direction. At this time, some of the lubricating oil is also introduced between the side gear 4 and the end washer 5 through the inner circumference slit 52, ensuring lubrication between the side gear 4 and the end washer 5. By making the shape of the inner circumference slit 52 such that its width in the circumferential direction widens towards its opening side (i.e., the inner circumference side), the lubricating oil is more easily guided into the inner circumference slit 52. In addition, the lubricating oil that has passed through the lubrication groove 233c to the outer circumference is discharged to the outside of the differential case 2 through the bore 27 and the through hole 232.

[0039] The multiple protrusions 233b are formed to be partially present in the circumferential direction. That is, the protrusions 233b are not formed continuously around the entire circumference. The multiple protrusions 233b cover the end washer 5 from the outer circumference. In this embodiment, the protrusion length of the protrusions 233b from the opposing portion 233a is shorter than the thickness of the end washer 5. Therefore, small wear particles collected in the outer peripheral slit 51 are discharged from the axially inner side of the protrusions 233b.

[0040] The protruding portion 233b serves to cut and reduce the mass 10, which is formed by the aggregation of numerous wear particles accumulated in the outer peripheral slit 51. This will be explained using Figures 7 and 8. Figure 7 is a cross-sectional view of the bottom portion 23 and the end washer 5, showing the state before the mass 10 is cut. Figure 8 is a cross-sectional view of the bottom portion 23 and the end washer 5, showing the state after the mass 10 has been cut.

[0041] As shown in Figure 7, as wear particles accumulate in the outer peripheral slit 51, the wear particles combine to form a large mass 10. In particular, when the wear particles are made of fluororesin, as in this embodiment, a large number of wear particles tend to combine with each other, making it easy for a large mass 10 to form. If this large mass 10 is discharged from the outer peripheral slit 51 toward the bore 27, the mass 10 may obstruct the rotational motion of the pinion gear assembly 3 inside the bore 27.

[0042] Therefore, in this embodiment, multiple protrusions 233b are provided that are partially present in the circumferential direction. As a result, even if a large mass 10 is formed within the outer peripheral slit 51, the end washer 5 and the differential case 2 rotate relative to each other, and when the circumferential positions of the outer peripheral slit 51 and the lubrication groove 233c are aligned as shown in Figure 7, the mass 10 will protrude from the outer peripheral slit 51. Furthermore, as the end washer 5 and the differential case 2 rotate relative to each other, the mass 10 will be cut by the outer peripheral slit 51 and the protrusions 233b as shown in Figure 8. In this way, the discharge of a large mass 10 from the outer peripheral slit 51 to the outer periphery is suppressed.

[0043] As shown in Figures 1 and 3, the center washer 6 is interposed between the pair of side gears 4. The center washer 6 has an annular shape, and five protrusions 61 are formed on its outer circumference so as to fit between the shaft portion 311 of the first pinion gear 31 and the shaft portion 321 of the second pinion gear 32 of each pinion gear set 3. This restricts the rotation of the center washer 6 relative to the differential case 2.

[0044] (Operation and effects of the first embodiment) In this embodiment of the differential gear 1, an outer peripheral slit 51 is formed in the end washer 5. Therefore, when friction occurs between the end washer 5 and the side gear 4 or differential case 2, and wear particles are generated, these wear particles are collected in the outer peripheral slit 51. As a result, it is possible to suppress the increase in frictional force between these points, for example, by preventing wear particles from entering between the end washer 5 and the side gear 4, and between the end washer 5 and the differential case 2. Furthermore, since the outer peripheral slit 51 is an open slit on the outer circumference side, the wear particles collected in the outer peripheral slit 51 are discharged outwards from the outer peripheral slit 51 by centrifugal force, such as when the differential case 2 rotates. Therefore, it is possible to suppress the acceleration of wear between the end washer 5 and the side gear 4 or differential case 2 due to the accumulation and enlargement of wear particles in the outer peripheral slit 51. In addition, since the end washer 5 is rotatable relative to at least one of the differential case 2 and the side gear 4, wear particles are collected in the outer peripheral slit 51 during this rotation. Therefore, it is possible to suppress the accumulation of wear particles between the end washer 5 and the differential case 2 or side gear 4.

[0045] Furthermore, a lubrication groove 233c is formed in the opposing portion 233a of the differential case 2 that faces the end washer 5 in the axial direction, allowing the lubricating oil flowing into the differential case 2 to circulate in a direction intersecting the axial direction. Therefore, the area between the end washer 5 and the differential case 2 is lubricated by the lubricating oil passing through the lubrication groove 233c. In addition, wear particles generated by friction between the end washer 5 and the differential case 2 or the side gear 4 are carried away by the lubricating oil flowing through the lubrication groove 233c, thus preventing the accumulation of wear particles around the end washer 5.

[0046] Furthermore, the end washer 5 is rotatable relative to the differential case 2, and multiple lubrication grooves 233c are formed on the opposing portion 233a at equal intervals in the circumferential direction. The end washer 5 has a different number of outer peripheral slits 51 formed at equal intervals in the circumferential direction than the number of lubrication grooves 233c formed on the opposing portion 233a. Therefore, because the multiple lubrication grooves 233c of the opposing portion 233a and the multiple outer peripheral slits 51 of the end washer 5 are in the same position in the circumferential direction, the contact area between the end washer 5 and the differential case 2 is reduced, and wear between the end washer 5 and the differential case 2 is suppressed.

[0047] Furthermore, the outer peripheral slit 51 is formed to extend further inward than the central position C between the inner peripheral surface 53 and the outer peripheral surface 54 in the radial direction of the end washer 5. In this way, because the outer peripheral slit 51 is formed over a wide radial range, when the end washer 5 rotates relative to at least one of the differential case 2 and the side gear 4, wear particles present between the end washer 5 and the differential case 2 or the side gear 4 are more easily collected in the outer peripheral slit 51. As a result, the accumulation of wear particles on both sides of the end washer 5 is suppressed.

[0048] Furthermore, the end washer 5 has a washer penetration portion (i.e., an inner circumferential slit 52) ​​that penetrates axially and is closed on the outer circumference. Therefore, lubricating oil is supplied to both sides of the end washer 5 through the washer penetration portion, which suppresses wear that occurs between the end washer 5 and the differential case 2 and side gear 4.

[0049] Furthermore, the end washer 5 has multiple outer peripheral slits 51 and multiple washer penetrations, and these multiple outer peripheral slits 51 and multiple washer penetrations are formed alternately in the circumferential direction. Therefore, the effect of collecting wear particles with the outer peripheral slits 51 and discharging them to the outer periphery, and the effect of guiding lubricating oil to both sides of the end washer 5 with the washer penetrations, are obtained evenly throughout the entire circumferential direction of the end washer 5.

[0050] Furthermore, the washer penetration portion is an inner circumference slit 52 that is open on the inner circumference side of the end washer 5. Therefore, lubricating oil on the inner circumference side of the end washer 5 is easily introduced into the inner circumference slit 52, promoting lubrication of both sides of the end washer 5. In addition, even if wear particles are collected in the inner circumference slit 52, the wear particles are easily discharged from the inner circumference slit 52.

[0051] Furthermore, the inner circumferential slit 52 is formed to extend beyond the central position C between the inner circumferential surface 53 and the outer circumferential surface 54 in the radial direction of the end washer 5, towards the outer circumference. In this way, because the inner circumferential slit 52 is formed over a wide radial range, when the end washer 5 rotates relative to at least one of the differential case 2 and the side gear 4, wear particles present between the end washer 5 and the differential case 2 or the side gear 4 are more easily collected into the inner circumferential slit 52.

[0052] Furthermore, in this embodiment, portions of the outer circumferential slit 51 and the inner circumferential slit 52 are formed in positions that overlap in the circumferential direction. Therefore, when the end washer 5 rotates relative to at least one of the differential case 2 and the side gear 4, wear particles present between the end washer 5 and the differential case 2 or side gear 4 are more easily collected by the outer circumferential slit 51 and the inner circumferential slit 52.

[0053] Furthermore, the end washer 5 is rotatable relative to the differential case 2, and the differential case 2 covers the end washer 5 from the outer circumference and has a projection 233b that is formed to be partially present in the circumferential direction. Therefore, even if the wear particles collected in the outer circumferential slit 51 combine to form a large mass 10, as shown in Figures 7 and 8, when the end washer 5 rotates relative to the differential case 2, the mass 10 is cut by the outer circumferential slit 51 and the projection 233b, preventing the mass 10 from being discharged from the outer circumferential slit 51 in its large state.

[0054] As described above, this embodiment provides a differential gear 1 that can suppress wear between the end washer and the side gear or differential case.

[0055] [Second Embodiment] Figure 9 is a cross-sectional view showing the overall configuration of the differential gear 1 in this embodiment.

[0056] This embodiment is a modification of the first embodiment, in which an intervening washer 7 is added between the side gear 4 and the end washer 5. The intervening washer 7 is positioned on the washer-facing surface 43 of the side gear 4. The intervening washer 7 has an annular shape, and at least the surface on the end washer 5 side is LAP-machined. The washer-facing surface 43 of the side gear 4 is not LAP-machined.

[0057] Otherwise, it is the same as in the first embodiment. In addition, among the reference numerals used in the second embodiment and subsequent embodiments, those that are the same as those used in the previously described embodiments represent the same components, etc., as those in the previously described embodiments, unless otherwise specified.

[0058] (Operation and effects of the second embodiment) While it is relatively difficult to perform LAP machining on the washer-facing surface 43 of the side gear 4, which has a complex shape, this embodiment makes it easier to improve the productivity of the differential 1 by interposing an interposing washer 7 between the end washer 5 and the washer-facing surface 43 and performing LAP machining on the surface of the interposing washer 7 that faces the end washer 5. Furthermore, it has the same effects and advantages as the first embodiment.

[0059] [Third Embodiment] Figure 10 is a cross-sectional view showing the overall configuration of the differential unit 1 in this embodiment.

[0060] The differential gear 1 in this embodiment is a so-called open differential that does not perform differential limiting. The differential gear 1 comprises a differential case 2, a pinion shaft 81 fixed to rotate integrally with the differential case 2, a pair of pinion gears 82 pivotally supported on the pinion shaft 81, a pair of side gears 83 meshed with the pair of pinion gears 82, and a pair of end washers 5 interposed between the pair of side gears 83 and the differential case 2, respectively. Note that for components of the differential gear 1 in this embodiment that are common with the first embodiment, redundant explanations will be omitted.

[0061] A pair of through holes 254 are formed in the side portion 25 of the differential case body 21 through which the pinion shaft 81 is inserted. The pinion shaft 81 is inserted into the pair of through holes 254 and is prevented from coming out of the insertion holes by retaining pins or the like (not shown in the figure). The central axis Y of the pinion shaft 81 extends in a direction perpendicular to the rotation axis X of the differential case 2. A pair of pinion gears 82 are fitted onto the pair of pinion gears 82.

[0062] The pinion gear 82 is a bevel gear that revolves in conjunction with the rotation of the differential case 2 and can also rotate on its own axis around the central axis Y of the pinion shaft 81. When the vehicle is moving in a straight line, the pair of pinion gears 82 revolve in conjunction with the rotation of the differential case 2, but do not rotate on their own. As a result, when the vehicle is moving in a straight line, each of the pair of side gears 83 rotates at the same speed as the rotation of the differential case 2. On the other hand, when the vehicle is turning, the pair of pinion gears 82 revolve in conjunction with the rotation of the differential case 2 and also rotate on their own. As a result, when the vehicle is turning, the pair of side gears 83 rotate differentially, and the differential case 2 and each side gear 83 rotate relative to each other. Therefore, friction may occur between the differential case 2 and each side gear 83 when the vehicle is turning.

[0063] A pair of side gears 83 are positioned on opposite sides of the pinion shaft 81 in the axial direction, and each meshes with a pair of pinion gears 82. An end washer 5 is positioned on the axially outer surface of the side gears 83. The configuration of the end washer 5 is the same as in the first embodiment. The end washer 5 is also positioned in a fitting recess 233 of the differential case 2. The configuration of the fitting recess 233 is also the same as in the first embodiment.

[0064] An annular space 20 is formed on the outer circumference of the side gear 83 inside the differential case 2, centered on the central axis Y of the pinion shaft 81. The annular space 20 communicates with the lubrication groove 233c formed in the fitting recess 233, and also communicates with the outside of the differential case 2 through the through hole 232 formed in the differential case 2. Otherwise, it is the same as in the first embodiment.

[0065] (Operation and Effects of the Third Embodiment) Even in an open differential type differential 1 like the one in this embodiment, the same effects and advantages as in the first embodiment can be obtained.

[0066] (Note) The present invention has been described above based on embodiments, but these embodiments do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention.

[0067] Furthermore, the present invention can be implemented by modifying it as appropriate, without departing from its spirit, by omitting some of its components, or by adding or substituting components. [Explanation of symbols]

[0068] 1...Differential device 2... Differential case 233a...Opposing part 233b…Protrusion 233c…lubrication groove 31...First pinion gear 32...Second pinion gear 4.83... Side gear 5… End washer 51…Outer perimeter slits 52...Inner circumference slit (washer penetration part) 53...Inner circumferential surface 54...Circumferential surface on the outer periphery 82... Pinion gear C...The midpoint between the inner circumferential surface and the outer circumferential surface in the radial direction.

Claims

1. Differential case and A pinion gear rotatably supported in the differential case, A pair of side gears that mesh with the pinion gear and are rotatable relative to the differential case, The device comprises an end washer positioned between at least one of the pair of side gears and the differential case, The end washer has an outer peripheral slit that penetrates axially and is open on the outer peripheral side. The inner circumferential surface of the end washer has an inner circumferential surface formed in a circular shape, The outer circumferential surface of the end washer has an outer circumferential surface formed in a circular shape, The outer peripheral slit is formed to extend further inward than the midpoint between the inner circumferential surface and the outer circumferential surface in the radial direction of the end washer. Differential device.

2. In the differential case, a lubrication groove is formed in the portion facing the end washer in the axial direction, which allows the lubricating oil flowing into the differential case to circulate in a direction intersecting the axial direction. The differential device according to claim 1.

3. The end washer is rotatable relative to the differential case, Multiple lubrication grooves are formed in the opposing portion at equal intervals in the circumferential direction. The end washer has a number of outer peripheral slits that are equal in the circumferential direction, different from the number of lubrication grooves formed in the opposing portion. The differential device according to claim 2.

4. The end washer has a washer penetration portion that extends axially and is closed on its outer circumference. A differential according to any one of claims 1 to 3.

5. The end washer has a plurality of outer peripheral slits and a plurality of washer through portions formed therein. The multiple outer peripheral slits and the multiple washer penetrations are formed alternately in the circumferential direction. The differential device according to claim 4.

6. The washer penetration portion is an inner circumferential slit in which the inner circumference side of the end washer is open. The differential device according to claim 4 or 5.

7. The inner circumferential slit is formed to extend outward beyond the midpoint between the inner circumferential surface and the outer circumferential surface in the radial direction of the end washer. The differential device according to claim 6.

8. The end washer is rotatable relative to the differential case, The differential case covers the end washer from the outer circumference and has a protrusion formed to be partially present in the circumferential direction. A differential according to any one of claims 1 to 7.

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