Constant velocity universal joint

Abstract

This enables the low-cost manufacturing of an outer joint member equipped with an engagement groove for engaging with a jig, without increasing its size. [Solution] An engaging member 40 is attached to the outer circumferential surface of an outer joint member 11 having a plurality of track grooves 15 on its inner circumference. The engaging member 40 has an engaging groove 42 on its outer circumferential surface that extends in the circumferential direction and can engage with the jig 50 in the axial direction.

Description

Technical Field

[0001] The present invention relates to a constant velocity joint used in a power transmission system of an automobile, an aircraft, a ship, various industrial machines, and the like.

Background Art

[0002] In an automobile drive shaft, it is necessary to cope with angular displacement and axial displacement due to changes in the relative positional relationship between the engine (or motor) and the wheels. Therefore, on the inboard side (the center side in the vehicle width direction), a sliding constant velocity joint that allows both angular displacement and axial relative movement between two shafts is used, and on the outboard side (the outer side in the vehicle width direction), a fixed constant velocity joint that allows angular displacement between two shafts but does not allow axial relative movement between the two shafts is used. The inner joint member of the sliding constant velocity joint and the inner joint member of the fixed constant velocity joint are connected via a shaft. The outer joint member of the sliding constant velocity joint is connected to the differential by press-fitting its shaft portion into the mounting hole of the gear constituting the differential and spline-fitting it with the gear.

[0003] In order to press-fit the shaft portion of the outer joint member constituting the sliding constant velocity joint into the differential, or to pull out the shaft portion of the press-fitted outer joint member from the differential, as shown in FIG. 10, an engagement groove 201 for engaging a press-fitting jig may be provided on the outer peripheral surface of the outer joint member 200 (Patent Document 1). In addition, it is also known to provide an axial groove on the outer peripheral surface of the outer joint member and an engagement protrusion protruding in the radial direction in the groove, and to engage a press-fitting jig with the engagement protrusion to perform press-fitting and pulling out of the outer joint member (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] To form the engagement groove described in Patent Document 1 or the engagement projection described in Patent Document 2, machining is required on the outer surface of the outer joint member, raising concerns about increased costs due to the increased number of processing steps. In the tripod-type joint described in Patent Document 1, the thickness of the outer joint member becomes partially thinner when the engagement groove is formed, and to compensate for this, the outermost diameter of the outer joint member must be increased. This would contradict the requirement for weight reduction.

[0006] Therefore, the present invention aims to enable the low-cost manufacturing of an outer joint member equipped with an engagement groove for engaging with a jig, without increasing its size. [Means for solving the problem]

[0007] To solve the aforementioned problems, the present invention provides a constant velocity universal joint comprising an outer joint member having a plurality of track grooves formed on its inner circumference, an inner joint member disposed inside the outer joint member, and a torque transmission member that transmits torque between the outer joint member and the inner joint member, wherein angular changes are permitted between the outer joint member and the inner joint member, characterized in that an engaging member is attached to the outer circumferential surface of the outer joint member, and the engaging member has an engaging groove on its outer circumferential surface that extends in the circumferential direction and can engage with a jig in the axial direction.

[0008] This configuration makes it possible to suppress the reduction in strength of the outer joint member compared to conventional products where engagement grooves are directly formed on the outer circumferential surface of the outer joint member. Therefore, the maximum outer diameter of the outer joint member can be made smaller than that of conventional products, thereby reducing the weight of the outer joint member. In addition, since groove processing of the outer joint member is unnecessary, the manufacturing cost of the outer joint member can be reduced.

[0009] The engaging member can be attached to the outer joint member by providing a groove extending in the circumferential direction on the outer circumferential surface of the outer joint member and fitting a projection provided on the inner circumferential surface of the engaging member into the groove.

[0010] The engaging member can also be attached to the outer joint member by a band member wrapped around the outer circumference of the engaging member.

[0011] A small-diameter section is provided on the outer circumferential surface of the outer joint member in the region between adjacent track grooves in the circumferential direction, with a smaller outer diameter than other areas. The groove is provided on the outer circumferential surface of the outer joint member, excluding the small-diameter section. The projection of the engaging member is made axially movable on the outer diameter side of the small-diameter section, and the engaging member can be inserted into the groove by rotating it in the circumferential direction. This allows the engaging member to be attached to the outer joint member without elastically deforming the projection, thereby improving workability during installation.

[0012] In the constant velocity universal joint described above, it is preferable that the outer joint member comprises a cylindrical portion having the track groove on its inner circumference and a bottom portion that closes one end of the cylindrical portion on the axial side, and that the engagement groove of the engagement member is located on the other axial side of the bottom portion. [Effects of the Invention]

[0013] According to the present invention, an outer joint member equipped with an engagement groove for engaging with a jig can be manufactured at low cost without increasing its size. [Brief explanation of the drawing]

[0014] [Figure 1] This is a longitudinal cross-sectional view of a tripod-type constant velocity universal joint along line II in Figure 2. [Figure 2] Figure 1 is a side view of a tripod-type constant velocity universal joint as seen from the X direction. [Figure 3] This is a longitudinal cross-sectional view of the outer joint member. [Figure 4] This is a cross-sectional view showing an enlarged view of the main part of Figure 3. [Figure 5] It is a longitudinal sectional view of an outer joint member. [Figure 6] It is a sectional view showing an enlarged main part of FIG. 5. [Figure 7] It is a side view of the engaging member seen from the axial direction. [Figure 8] It is a side view of the outer joint member with the engaging member externally fitted, seen from the axial direction. [Figure 9] It is a side view of the outer joint member with the engaging member externally fitted, seen from the axial direction. [Figure 10] It is a longitudinal sectional view of an outer joint member of a conventional tripod constant velocity joint.

Embodiments for Carrying out the Invention

[0015] The first to third embodiments of the constant velocity joint according to the present invention will be described in detail below based on the drawings. Before explaining the characteristic configurations of each embodiment, the overall configuration of the constant velocity joint will be described.

[0016] As already described, there are two types of constant velocity joints: fixed type and sliding type. In the following description, the case where the present invention is applied to a sliding constant velocity joint installed on the inboard side of the drive shaft when mounted on a vehicle, more specifically, a tripod constant velocity joint, will be exemplified.

[0017] FIGS. 1 and 2 show the overall configuration of a tripod constant velocity joint. FIG. 1 is a longitudinal sectional view taken along line I-I of FIG. 2, and FIG. 2 is a side view seen from the X direction of FIG. 1 (in FIG. 2, only one roller 13 is shown in section).

[0018] The constant velocity joint includes an outer joint member 11 having a plurality of track grooves 15 formed on its inner circumference, an inner joint member 12 disposed inside the outer joint member 11, and a torque transmission member 13 that transmits torque between the outer joint member 11 and the inner joint member 12. In a tripod constant velocity joint, a tripod member 12 is used as the inner joint member, and a roller 13 is used as the torque transmission member.

[0019] The outer coupling member 11 integrally comprises a bottomed cup-shaped body 110 and a shaft portion 111 extending axially from the bottom portion of the body 110. The body 110 integrally comprises a cylindrical portion 112 with a track groove 15 formed on its inner circumference and a bottom portion 113 that closes the end of the cylindrical portion 112 on one axial side (shaft portion 111 side). A male spline 114 is formed on the outer circumferential surface of the tip of the shaft portion 111. By fitting this male spline 114 with a female spline formed on a differential gear (not shown), the gear and the outer coupling member 11 are coupled in a torque-transmitting manner.

[0020] As shown in Figure 2, the cylindrical portion 112 has three linear track grooves 15 extending in the axial direction, formed at three equally spaced locations in the circumferential direction of the cylindrical inner surface 16. Each track groove 15 has a pair of roller guide surfaces 17 facing each other on its inner walls. The roller guide surfaces 17 have an arc-shaped cross-section and extend parallel to the axial direction of the outer joint member 11. In addition, small-diameter portions 115, which have a smaller outer diameter than other portions, are formed at three equally spaced locations in the circumferential direction of the outer surface of the main body 110. The small-diameter portions 115 are formed continuously over the entire axial direction of the outer surface of the main body 110 in the region between adjacent track grooves 15 in the circumferential direction. Except for the small-diameter portions 115, the outer surface of the main body 110 is cylindrical.

[0021] The tripod member 12 has a cylindrical body 18 on which three leg shafts 19 are integrally formed radially at equal intervals (120° intervals) in the circumferential direction. The leg shafts 19 extend radially, and their tips reach near the bottom of the track groove 15. The outer surface of the leg shafts 19 is generally cylindrical. The shaft end 22 of the shaft 21 is connected to the shaft hole 20 of the body 18 by spline fitting. The shaft 21 is prevented from coming off the tripod member 12 by a retaining ring 23.

[0022] A roller 13 is rotatably disposed between the roller guide surface 17 of the outer joint member 11 and the outer circumferential surface of the leg shaft 19 via needle-shaped rollers 24. The outer circumferential surface of the roller 13 has a vertical arc shape, and may contact the roller guide surface 17 at two points through angular contact, or at one point through circular contact. The inner circumferential surface of the roller 13 is formed in a cylindrical shape.

[0023] Multiple needle-shaped rollers 24 are arranged between the roller 13 and the shaft 19 in a so-called single-row full-roller configuration without a cage. The outer circumferential surface of the shaft 19 constitutes the inner rolling surface of the needle-shaped rollers 24, and the inner circumferential surface of the roller 13 constitutes the outer rolling surface of the needle-shaped rollers 24.

[0024] The needle roller 24 is in contact with an inner washer 27 fitted onto the base 25 of the leg shaft 19 on the radially inward side, and with an outer washer 28 fitted onto the tip of the leg shaft 19 on the radially outward side. As a result, the axial movement of the needle roller 24 relative to the leg shaft 19 is restricted. The outer washer 28 is prevented from coming off by fitting a retaining ring 30 into the annular groove 29 of the leg shaft 19.

[0025] In the constant velocity universal joint configured as described above, the leg shaft 19 of the tripod member 12 and the roller guide surface 17 of the outer joint member 11 engage in the rotational direction of both axes via the roller 13, thereby transmitting rotational torque at a constant speed from the driving side to the driven side.

[0026] Furthermore, as the roller 13 rotates relative to the leg shaft 19 and rolls on the roller guide surface 17, relative axial and angular displacements between the outer joint member 11 and the tripod member 12 are permitted.

[0027] In this type of constant velocity universal joint, a lubricant such as grease (not shown) is sealed in the internal space of the outer joint member 11 to ensure lubrication at the sliding parts inside the joint, that is, at the sliding parts of each component of the outer joint member 11, tripod member 12, needle roller 24, and roller 13, when the joint is operated.

[0028] Furthermore, this constant velocity universal joint has a structure in which a bellows-shaped boot 31 made of resin or rubber is fitted between the opening of the cylindrical portion 112 of the outer joint member 11 and the shaft 21, in order to prevent leakage of the lubricant sealed inside the joint and to prevent foreign matter from entering from outside the joint.

[0029] Next, the characteristic configuration of the present invention will be described. Figures 3 and 4 show a first embodiment of the present invention. Note that in Figure 3, the illustration of the components constituting the tripod-type constant velocity universal joint is omitted, except for the outer joint member 11 and the engaging member 40 (the same applies to Figures 5, 8, and 9).

[0030] As shown in Figure 3, an engaging member 40 is attached to the outer circumferential surface of the main body 110 of the outer joint member 11. The engaging member 40 can be formed by molding a resin material. The resin material selected has sufficient strength to withstand the press-fit load and pull-out load applied from the jig described later. As long as these required characteristics are met, both thermosetting resins and thermoplastic resins can be used as the resin material. By forming the engaging member 40 from a resin material, the weight increase of the tripod-type constant velocity universal joint can be minimized.

[0031] The engaging member 40 is formed in a circumferential arc or annular shape. A projection 41 extending in the circumferential direction is formed on the inner circumferential surface of the engaging member 40, and a groove 116 extending in the circumferential direction is formed on the outer circumferential surface of the main body 110 that engages with this projection 41. The engaging member 40 is inserted onto the outer circumference of the main body 110 while elastically deforming the projection 41, and when it faces the groove 116, the projection 41 elastically returns to its original position, causing the projection 41 to engage with the groove 116. In this way, the engaging member 40 is attached to the outer circumferential surface of the main body 110 of the outer joint member 11. It is preferable to attach the engaging member 40 near the end of the main body 110 on the shaft portion 111 side, considering the workability during press-fitting. In this embodiment, the groove 116 is provided on the outer diameter side of the rounded portion 117 that connects the cylindrical inner circumferential surface 112a of the cylindrical portion 112 and the end face 113a of the bottom portion 113. However, the groove 116 may also be provided on the outer diameter side of the bottom portion 113. Providing the groove 116 on the outer diameter side of the inner circumferential surface 112a of the cylindrical portion 112 is undesirable because it can reduce the strength of the cylindrical portion 112.

[0032] An engagement groove 42 extending in the circumferential direction is formed on the outer circumferential surface of the engagement member 40. It is preferable that the engagement groove 42 be provided on the other axial side (the opening side of the cylindrical portion 112) of the projection 41. This ensures that the projection 41 is formed on the thicker portion of the engagement member 40, thereby ensuring the strength of the projection 41. It is preferable that the engagement groove 42 be provided on the other axial side (the opening side of the cylindrical portion 112) of the bottom portion 113 of the main body 110. It is preferable that the axial sides 42a and 42b of the engagement groove 42 be formed as surfaces extending in a direction perpendicular to the axial direction so that they can reliably engage with the jig 50.

[0033] The tripod-type constant velocity universal joint described above is assembled to the vehicle with the engaging member 40 attached to the outer joint member 11. Specifically, by pressing the jig 50 against the engaging groove 42 of the engaging member 40 and pushing one side surface 42a of the engaging member 40 on the shaft portion 111 side in the axial direction (arrow direction in Figure 3), the shaft portion 111 of the outer joint member 11 is press-fitted into the mounting hole of the gear constituting the differential. The engaging member 40 remains attached to the outer joint member 11 even while the vehicle is in use. When removing the drive shaft from the differential for vehicle maintenance, etc., the shaft portion 111 of the outer joint member 11 can be pulled out from the gear by pressing the jig 50 against the engaging groove 42 of the engaging member 40 and pushing the other side surface 42b of the engaging member 40 towards the opening of the cylindrical portion 112.

[0034] As in the present invention, by attaching an engaging member 40 to the outer circumferential surface of the outer joint member 11 and providing an engaging groove 42 on the outer circumferential surface of the engaging member 40 that extends in the circumferential direction and can engage with the jig 50 in the axial direction, the reduction in strength of the outer joint member 11 can be suppressed compared to the case where an engaging groove 201 is directly formed on the outer circumferential surface of the outer joint member 200, as in the conventional product shown in Figure 10. Therefore, the maximum outer diameter dimension φD1 of the outer joint member 11 shown in Figure 3 can be made smaller than that of the conventional product shown in Figure 10, thereby reducing the weight of the outer joint member 11. In addition, since groove processing of the outer joint member 11 is unnecessary, the manufacturing cost of the outer joint member 11 can be reduced.

[0035] Figures 5 and 6 show a second embodiment of the present invention. In the second embodiment, the engaging member 40 having the engaging groove 42 described in the first embodiment is attached to the outer joint member 11 using a band member 44 wrapped around its outer circumference. As shown in Figure 6, the band member 44 is attached to a mounting groove 43 provided on the outer circumferential surface of the engaging member 40 on the side opposite the shaft portion to the engaging groove 42. By tightening the band member 44 and reducing its diameter, the engaging member 40 is fixed to the outer joint member 11 by the tightening force.

[0036] With the configuration of this second embodiment, the processing of the groove 116 provided on the outer circumferential surface of the outer joint member 11 becomes unnecessary, thus further reducing the manufacturing cost of the outer joint member 11.

[0037] Figures 7 to 9 show a third embodiment of the present invention. In the first embodiment, the projection 41 is elastically deformed while the engaging member 40 is slid axially to fit the projection 41 into the groove 116. In the third embodiment, the engaging member 40 is rotated about the joint axis to fit the projection 41 into the groove 116 without elastic deformation.

[0038] Specifically, as shown in Figure 7, the engaging member 40 is integrally provided with an annular portion 46 and a circumferential projection 41 that protrudes inward from the inner circumferential surface of the annular portion 46. In addition, circumferential grooves 116 are provided at three locations on the outer circumferential surface of the main body 110, excluding the small diameter portion 115. Both circumferential ends of the grooves 116 open into the space demarcated by the small diameter portion 115. As shown in Figure 8, when the ring-shaped engaging member 40 is fitted onto the cylindrical portion 112, the projections 41 are formed to face the small diameter portion 115 radially and to be able to move axially without interfering with the small diameter portion 115 on the outer diameter side of the small diameter portion 115. The grooves 116 can be provided in the same axial position as the grooves shown in Figure 3.

[0039] As shown in Figure 8, the engaging member 40 is fitted to the outer circumferential surface of the main body 110 of the outer joint member 11 with the projection 41 aligned with the circumferential phase of the small diameter portion 115. Then, the engaging member 40 is pushed axially until the projection 41 faces the opening of the groove portion 116. After that, as shown in Figure 9, the engaging member 40 is rotated circumferentially to insert the projection 41 into the groove portion 116. As a result, as shown in Figure 4, the projection 41 and the groove portion 116 are fitted together, and the engaging member 40 is attached to the outer circumferential surface of the outer joint member 11. In the third embodiment, since it is not necessary to elastically deform the projection 41, the installation work of the engaging member 40 can be simplified.

[0040] In the embodiments described above, an example was shown of an outer joint member 11 of a tripod-type constant velocity universal joint in which small-diameter portions 115 are provided at three locations on the outer circumferential surface of the main body 110. However, the present invention can also be applied to an outer joint member 11 in which the outer circumferential surface of the main body 110 is formed into a cylindrical shape with a uniform diameter around its entire circumference without providing small-diameter portions 115.

[0041] Furthermore, in the embodiments described above, a single-roller type tripod-type constant-velocity universal joint was exemplified, where one roller 13 is supported by each leg shaft 19. However, the present invention is not limited to the single-roller type, but can also be applied to a double-roller type tripod-type constant-velocity universal joint that supports two rollers (for example, an inner ring and a roller) concentrically arranged on each leg shaft 19. Moreover, the present invention is not limited to tripod-type constant-velocity universal joints, but can also be applied to other types of sliding constant-velocity universal joints, such as double-offset type constant-velocity universal joints. In addition, the present invention can also be applied to fixed-type constant-velocity universal joints (such as Zeppa-type constant-velocity universal joints, undercut-free type constant-velocity universal joints, and cross-groove type constant-velocity universal joints) if they are pressed into or removed from other members using a jig. [Explanation of Symbols]

[0042] 11. Outer joint member 12. Tripod members (internal joint members) 13. Roller (torque transmission member) 15 Track grooves 40 Engaging member 42 Engagement groove 44 Band members 47 Ribs 50 jigs 112 Cylindrical part 113 Bottom 115 Small diameter section 119 Rib housing groove

Claims

1. A constant velocity universal joint comprising an outer joint member having multiple track grooves formed on its inner circumference, an inner joint member positioned inside the outer joint member, and a torque transmission member that transmits torque between the outer joint member and the inner joint member, wherein angular changes are permitted between the outer joint member and the inner joint member, An engaging member is attached to the outer circumferential surface of the outer joint member. A constant velocity universal joint characterized in that the engaging member has an engaging groove on its outer surface that extends in the circumferential direction and can engage with a jig in the axial direction.

2. The constant velocity universal joint according to claim 1, wherein a groove extending in the circumferential direction is provided on the outer circumferential surface of the outer joint member, and the engaging member is attached to the outer joint member by fitting a projection provided on the inner circumferential surface of the engaging member into the groove.

3. The constant velocity universal joint according to claim 1, wherein the engaging member is attached to the outer joint member by a band member wrapped around the outer circumference of the engaging member.

4. A constant velocity universal joint according to claim 2, wherein a small-diameter portion is provided on the outer circumferential surface of the outer joint member in the region between adjacent track grooves in the circumferential direction, the groove portion is provided on the outer circumferential surface of the outer joint member excluding the small-diameter portion, the projection of the engaging member is movable in the axial direction on the outer diameter side of the small-diameter portion, and the engaging member can be inserted into the groove portion by rotating it in the circumferential direction.

5. The constant velocity universal joint according to claim 1, wherein the outer joint member comprises a cylindrical portion having the track groove on its inner circumference and a bottom portion that closes one axial end of the cylindrical portion, and the engagement groove of the engagement member is located on the other axial side of the bottom portion.

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