CN117957382A - Tripod constant velocity universal joint - Google Patents

Abstract

In a tripod type constant velocity universal joint (1) of a double-row roller type, snap rings (14, 15) for restricting movement of an inner ring (12) in the axial direction of a foot shaft (32) are provided on the inner periphery of an outer ring (11), and the snap rings (14, 15) are fitted into mounting grooves (11 a) formed on the inner peripheral surface of the outer ring (11). The snap rings (14, 15) are provided with slits (C) extending in a direction inclined with respect to the radial direction thereof. The outer diameter dimension before elastic deformation of the snap rings (14, 15) is set to D, the width dimension is set to b, the thickness is set to t, and the D/b is set to 7.4 < 9.8, and the b/t is set to 2.8 < 4.6.

Description

Tripod constant velocity universal joint

Technical Field

The present invention relates to a tripod type constant velocity universal joint for power transmission of automobiles and various industrial machines.

Background

In a drive shaft used in a power transmission system of an automobile, a sliding type constant velocity universal joint is often coupled to an inner side (a central side in a vehicle width direction) of an intermediate shaft, and a fixed type constant velocity universal joint is often coupled to an outer side (an end side in the vehicle width direction). The sliding type constant velocity universal joint referred to herein is a constant velocity universal joint that allows both angular displacement and axial relative movement between two shafts, and the fixed type constant velocity universal joint is a constant velocity universal joint that allows angular displacement but does not allow axial relative movement between two shafts.

As a sliding type constant velocity universal joint, a tripod type constant velocity universal joint is known. As the tripod type constant velocity universal joint, there are a single row roller type and a double row roller type. The single row roller type rotatably mounts the rollers inserted into the track grooves of the outer joint member to the foot shafts of the tripod members via a plurality of needle rollers. The double row roller type roller is provided with a roller inserted into a raceway groove of an outer joint member, and is externally fitted to a foot shaft of a tripod member to support the roller as a rotatable inner ring. The double row roller type has an advantage that the roller can be swung about the foot shaft, and therefore, the induced thrust (axial force induced by friction between members in the coupling) and the sliding resistance can be reduced, respectively, as compared with the single row roller type.

Patent document 1 below discloses an example of a tripod type constant velocity universal joint of a double row roller type. In such a double-row roller type tripod constant velocity universal joint, the rollers are rotatably disposed on the outer periphery of the inner race via needle rollers. The needle roller and the inner ring are prevented from falling off by a pair of snap rings assembled on the inner peripheral surface of the roller. That is, a pair of mounting grooves are formed on the inner peripheral surface of the roller so as to be separated in the foot axis direction at intervals corresponding to the length of the needle roller, and snap rings are fitted in the mounting grooves, respectively.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2000-320563

Disclosure of Invention

Problems to be solved by the invention

However, conventionally, in designing a snap ring, there has been no special consideration concerning both workability and durability (strength) at the time of mounting thereof. Specifically, regarding the mountability of the snap ring, the smaller the width dimension of the snap ring (the width dimension in the radial direction of the snap ring) is relative to the diameter dimension of the snap ring, the more elasticity of the snap ring increases and thus the better the assemblability is.

On the other hand, when the width dimension of the snap ring becomes smaller, the durability or strength of the snap ring decreases. That is, in the rotational drive of the coupling at the differential angle, the roller unit including the rollers, the inner ring, and the needle roller repeatedly slides in the axial direction of the footshaft with respect to the footshaft, and at this time, a repeated load acts from the inner ring on the retainer ring fitted to the inner peripheral surface of the rollers. When the width dimension of the snap ring is small, the contact area between the snap ring and the inner ring is small, and as a result, the contact surface pressure due to repeated load increases, resulting in a decrease in durability of the snap ring.

In this way, according to the verification by the present inventors, it is clear that the attachment workability and durability (strength) of the snap ring are in a relationship in which the other side is reduced when one side is improved. The conventional snap ring is not designed in consideration of this relationship, and has not been a standard for improving both the mounting workability and the durability (strength).

Accordingly, an object of the present invention is to provide a tripod type constant velocity universal joint in which both workability in attachment of a snap ring and durability or strength are achieved.

Means for solving the problems

The present invention, which has been completed based on the above-described findings, is a tripod type constant velocity universal joint comprising: an outer joint member having, at three locations in the circumferential direction, track grooves extending in the joint axial direction, each track groove having a pair of roller guide surfaces disposed opposite each other in the joint circumferential direction; a tripod member including a main body portion having a center hole and three leg shafts protruding in a radial direction of the main body portion; a roller fitted to each of the leg shafts; and an inner race which is fitted around the foot shaft and rotatably supports the roller, wherein the roller is movable in an axial direction of the outer joint member along the roller guide surface, wherein the roller and the inner race constitute a roller unit swingable with respect to the foot shaft, wherein a regulating member (a retainer ring) for regulating movement of the inner race in the axial direction of the foot shaft is provided on an inner periphery of the roller, and wherein the regulating member is fitted into a mounting groove formed on an inner peripheral surface of the roller, wherein the regulating member has an annular shape having an elastically contractible diameter and is provided with a slit extending in a direction inclined with respect to a radial direction of the regulating member, wherein an outer diameter dimension of the regulating member is D, a width dimension is b, and a thickness is t, and wherein 7.4 < D/b < 9.8 and 2.8 < b/t < 4.6 are satisfied.

Preferably, the restricting member is capable of elastically reducing the diameter to a diameter smaller than the inner diameter of the roller by overlapping both ends.

Preferably, the inner peripheral surface of the inner ring is formed in an arcuate convex surface in a longitudinal section of the inner ring, the outer peripheral surface of the footshaft is in a straight shape in a longitudinal section including an axis of the footshaft and in a substantially elliptical shape in a cross section orthogonal to the axis of the footshaft, and the outer peripheral surface of the footshaft abuts against the inner peripheral surface of the inner ring in a direction orthogonal to an axis of the coupling and a gap is formed between the outer peripheral surface of the footshaft and the inner peripheral surface of the inner ring in an axis direction of the coupling.

Preferably, a plurality of rolling elements are disposed between the inner race and the rollers. As the rolling element, for example, a needle roller can be used.

Effects of the invention

According to the present invention, a tripod type constant velocity universal joint can be provided that combines both workability in attachment of a snap ring and durability or strength.

Drawings

Fig. 1 is a cross-sectional view in the coupling axial direction showing a tripod type constant velocity universal joint of a double row roller type.

Fig. 2 is a cross-sectional view taken along line K-K of fig. 1.

Fig. 3 is a cross-sectional view taken along line L-L of fig. 1.

Fig. 4 is a cross-sectional view showing a state in which the tripod type constant velocity universal joint of fig. 1 is in an operating angle.

Fig. 5 is a plan view of the roller unit attached to the foot shaft as viewed from the direction a in fig. 2.

Fig. 6 is a sectional view of the roller unit along the axial direction of the footshaft.

Fig. 7 is a view showing a mounting sequence of the retainer ring on the toe end side of the foot shaft to the roller unit in a cross section along the axial direction of the foot shaft.

Fig. 8is a top view of the snap ring.

Fig. 9 is a cross-sectional view of the M-M line of fig. 8.

Fig. 10 is a sectional view of the roller unit along the axial direction of the footshaft.

Detailed Description

An embodiment of the tripod type constant velocity universal joint according to the present invention will be described with reference to fig. 1 to 10.

The tripod type constant velocity universal joint 1 according to the present embodiment shown in fig. 1 to 4 is of a double row roller type. Fig. 1 is a cross-sectional view in the axial direction of a tripod type constant velocity universal joint of the double row roller type, and fig. 2 is a cross-sectional view taken from the line K-K in fig. 1. Fig. 3 is a cross-sectional view taken along line L-L of fig. 1, and fig. 4 is a cross-sectional view showing an axial direction of the tripod type constant velocity universal joint when the working angle is taken. In the following description, the coupling axial direction and the coupling circumferential direction refer to the axial direction and the circumferential direction of the tripod type constant velocity universal joint, respectively, when the operating angle is set to 0 °.

As shown in fig. 1 and 2, the main portion of the tripod type constant velocity universal joint 1 includes an outer joint member 2, a tripod member 3 as an inner joint member, and a roller unit 4 as a torque transmission member. The outer joint member 2 has a cup shape with one end open, and three linear track grooves 5 extending in the joint axial direction are formed on the inner peripheral surface at equal intervals in the joint circumferential direction. Each of the raceway grooves 5 is formed with a roller guide surface 6 which is disposed so as to face each other in the joint circumferential direction of the outer joint member 2 and extends in the joint axial direction. A tripod member 3 and a roller unit 4 are housed in the outer joint member 2.

The tripod member 3 integrally has: a main body 31 (trunnion main body) having a center hole 30; three foot shafts 32 (trunnion journals) which project in the radial direction from the coupling circumferential direction trisection position of the outer peripheral surface of the main body 31. The tripod member 3 is coupled to the shaft member 8 so as to be capable of transmitting torque by fitting the external spline 81 formed on the shaft member 8 as a shaft to the internal spline 34 formed in the center hole 30 of the trunnion main body 31. The end face of one side of the tripod member 3 in the coupling axial direction is engaged with the shoulder 82 provided on the shaft member 8, and the retainer ring 10 fitted to the tip end of the shaft member 8 is engaged with the end face of the other side of the tripod member 3 in the coupling axial direction, whereby the tripod member 3 is fixed to the shaft member 8 in the coupling axial direction.

The main portion of the roller unit 4 includes an annular outer ring 11 as a roller centered on the axis of the stub shaft 32, an annular inner ring 12 disposed on the inner diameter side of the outer ring 11 and externally fitted to the stub shaft 32, and a plurality of rolling elements 13 interposed between the outer ring 11 and the inner ring 12. In the present embodiment, as an example of the rolling elements 13, a needle roller in a full-load roller state without a cage is used. The roller unit 4 is accommodated in the raceway groove 5 of the outer joint member 2. As described in detail later, the roller unit 4 including the outer ring 11, the inner ring 12, and the needle roller 13 is configured so as not to be naturally decomposed by the steel retainer rings 14 and 15 serving as the restricting members.

In the present embodiment, the outer peripheral surface 11a (see fig. 2) of the outer ring 11 is a convex curved surface having an arc having a center of curvature on the axis of the foot shaft 32 as a generatrix. The outer peripheral surface 11a of the outer race 11 is in angular contact with the roller guide surface 6.

The needle roller 13 is disposed so as to be rotatable between the outer raceway surface and the inner raceway surface with the cylindrical inner peripheral surface of the outer ring 11 being the outer raceway surface and the cylindrical outer peripheral surface of the inner ring 12 being the inner raceway surface.

The outer peripheral surface of each of the footshafts 32 of the tripod member 3 has a straight shape in the axial direction of the footshaft 32 in a cross section in any direction including the axis of the footshaft 32. As shown in fig. 3, the outer peripheral surface of the foot shaft 32 has a substantially elliptical shape in a cross section orthogonal to the axis of the foot shaft 32. The outer peripheral surface of the foot shaft 32 contacts the inner peripheral surface 12a of the inner race 12 in a direction orthogonal to the coupling axial direction, that is, in the direction of the long axis a. A gap m is formed between the outer peripheral surface of the foot shaft 32 and the inner peripheral surface 12a of the inner race 12 in the coupling axial direction, that is, in the direction of the short axis b.

As shown in fig. 1 and 2, the intermediate portion 33 between the body portion 31 of the tripod member 3 and the foot shaft 32 is formed so as to draw a concave curve in an arbitrary cross section including the axis of the foot shaft 32.

The inner peripheral surface 12a of the inner ring 12 has a convex arc shape in an arbitrary cross section including the axis of the inner ring 12. In this case, and in the case where the cross-sectional shape of the foot shaft 32 is substantially elliptical as described above, a predetermined gap m is provided between the foot shaft 32 and the inner ring 12, the inner ring 12 can swing with respect to the foot shaft 32. As described above, since the inner ring 12 and the outer ring 11 are assembled to be rotatable relative to each other via the needle rollers 13, the outer ring 11 and the inner ring 12 can swing integrally with respect to the foot shaft 32. That is, in a plane including the axis of the foot shaft 32, the axes of the outer race 11 and the inner race 12 can be inclined with respect to the axis of the foot shaft 32 (see fig. 4).

As shown in fig. 4, when the tripod type constant velocity universal joint 1 rotates at the operating angle, the axis of the tripod member 3 is inclined with respect to the axis of the outer joint member 2, but the roller unit 4 can swing, so that the outer race 11 and the roller guide surface 6 can be prevented from being in a skew state. As a result, the outer race 11 rolls horizontally on the roller guide surface 6, and thus the induced thrust and the sliding resistance can be reduced, and the vibration of the tripod constant velocity universal joint 1 can be reduced.

As described above, since the cross section (cross section) of the leg shaft 32 is substantially elliptical and the cross section (vertical cross section) of the inner peripheral surface 12a of the inner ring 12 is a circular arc-shaped convex cross section, the outer peripheral surface of the leg shaft 32 on the torque load side is in point contact with the inner peripheral surface 12a of the inner ring 12 at the contact point X or in a narrow area close to the point contact as shown in fig. 3. Thus, to reduce the force of tilting the roller unit 4, the stability of the posture of the outer race 11 improves.

Fig. 5 is a plan view of the roller unit 4 attached to the footaxle 32 as viewed from the direction a of fig. 2, and fig. 6 is a cross-sectional view of the roller unit 4 along the axial direction of the footaxle 32.

As shown in fig. 5 and 6, in the roller unit 4, an attachment groove 11a is provided on the inner peripheral surface of the outer ring 11 so as to be separated from the outer ring in the axial direction of the foot shaft 32. The snap rings 14 and 15 are fitted in the mounting groove 11a, and are thereby mounted on the inner peripheral surface of the outer ring 11 so as to be separated in the axial direction of the foot shaft 32. The retainer rings 14 and 15 face end surfaces of the needle roller 13 and the inner ring 12 on both axial sides of the foot shaft 32, and relative movement of the needle roller 13 and the inner ring 12 with respect to the outer ring 11 in the axial direction of the foot shaft 32 is restricted by the retainer rings 14 and 15. Therefore, natural disassembly of the roller unit 4 is restricted by the snap rings 14, 15.

Fig. 7 shows a sequence of attachment of the snap ring 14 on the coupling outer diameter side to the roller unit 4in a cross-sectional view taken along the axial direction of the foot shaft 32. Fig. 8 is a top view of the snap ring 14, and fig. 9 is a cross-sectional view taken along line M-M of fig. 8. Fig. 10 is a sectional view of the roller unit 4 along the axial direction of the footshaft 32.

As shown in fig. 8, the retainer ring 14 has a slit C (gap in the circumferential direction), and is formed in an end ring shape broken by the slit C. The retainer ring 14 has a shape in which the band plate is wound around an axis extending in the thickness direction thereof. The slit C extends in a direction inclined with respect to the radial direction of the snap ring 14.

As shown in fig. 7, in a state where the outer ring 11, the inner ring 12, and the needle roller 13 are assembled, the retainer ring 14 is attached to the attachment groove 11a of the inner peripheral surface of the outer ring 11. Specifically, an external force is applied to the snap ring 14 in a direction to bring the both ends 21, 22 closer to each other, the snap ring 14 is elastically reduced in diameter until the both ends 21, 22 overlap and the outer diameter dimension phid of the snap ring 14 (the diameter dimension in a natural state in which no external force is applied) becomes equal to or smaller than the inner diameter dimension phid of the outer ring 11, the reduced-diameter snap ring 14 is inserted into the inner periphery of the outer ring 11, and thereafter, the snap ring 14 is elastically expanded in diameter due to release of the external force and fitted into the fitting groove 11a, whereby the fitting of the snap ring 14 is completed. The outer peripheral surface of the snap ring 14 after mounting contacts the bottom surface of the mounting groove 11a.

In the present embodiment, the shape of the snap ring 14 is distinguished from the standpoint of both the workability of attachment of the snap ring 14 and durability or strength, as described below.

In terms of workability in mounting the snap ring 14, it is preferable that the smaller the radial width dimension b (see fig. 8 and 9) of the snap ring 14 is. As the width dimension b is smaller, the cross-sectional area of the snap ring shown in fig. 9 is smaller, and therefore the snap ring 14 is easily elastically deformed. Therefore, workability in attaching the snap ring 14 to the attachment groove 11a is improved. Similarly, as the outer diameter D of the snap ring 14 increases, the snap ring 14 is more likely to be elastically deformed, and therefore the workability of attachment of the snap ring 14 improves.

From the above verification result, it is considered that the easiness of elastic deformation of the snap ring 14, that is, the mounting workability can be evaluated from the value of D/b. When the value of D/b is too small, elastic deformation of the snap ring 14 is difficult to occur, and the workability of installation is lowered. On the other hand, if the value of D/b is too large, the snap ring 14 increases in the radial direction thereof, which violates the demand for downsizing of the tripod type constant velocity universal joint 1. From the above point of view, it is preferable to set the range of 7.4 < D/b < 9.8.

In terms of durability of the snap ring 14, it is preferable that the larger the radial width dimension b (see fig. 8 and 9) of the snap ring 14 is. As shown in fig. 10, in the differential angle rotation driving of the coupling, the roller unit 4 including the outer ring 11, the inner ring 12, and the needle roller 13 repeatedly slides with respect to the foot shaft 32 in the axial direction (up-down direction in the drawing) of the foot shaft 32, and at this time, a repeated load P acts on the retainer ring 14 from the inner ring 12 (in fig. 10, the retainer ring 15 on the foot shaft root side is shown, but the repeated load P acts on the retainer ring 14 on the foot shaft tip side in the same manner). When the width dimension b of the snap ring 14 is small, the width S of the contact area between the snap ring 14 and the inner ring 12 is small, and as a result, the contact surface pressure caused by the load P increases, resulting in a decrease in the durability or strength of the snap ring 14.

If the thickness t of the snap ring 14 shown in fig. 9 is too small, the durability or strength of the snap ring 14 is lowered. Conversely, if the thickness t of the retainer ring 14 is excessively large, the dimension in the axial direction of the foot shaft 32 of the roller unit 4 increases.

From the above verification results, it is considered that the durability or strength of the snap ring 14 can be evaluated from the value of b/t. When the value of b/t is too small, the durability or strength of the snap ring 14 is lowered, and when it is too large, the degree of freedom of design for suppressing the roller unit 4 to a predetermined size is lowered, and downsizing of the roller unit 4 becomes difficult. From the above viewpoints, it is preferable to set the range of 2.8 < b/t < 4.6.

Therefore, by designing the snap ring 14 so as to satisfy 7.4 < D/b < 9.8 and 2.8 < b/t < 4.6, it is possible to achieve both the workability of mounting the snap ring 14 and durability or strength. Regarding the relationship between these characteristics and the width dimension b of the snap ring 14, the relationship is in a legally reverse relationship in which one characteristic is reduced when the other characteristic is designed with importance attached, but the present embodiment is characterized in the following aspects: parameters are proposed that take into consideration other dimensions (D and t) in addition to the width dimension b of the snap ring 14, and it has been found that setting the optimum range of values for both D/b and b/t can achieve both of the workability of attachment and durability or strength.

In addition to the dimensional relationship of the snap ring 14 described above, the ratio (S/D) of the width S of the contact area between the snap ring 14 and the inner ring 12 to the outer diameter dimension phid of the snap ring 14 is preferably set to a range of 0.005 < S/D < 0.035. When the value of S/D is excessively large, the roller unit 4 is large in the radial direction of the axis of the foot shaft 32, and when the value of S/D is excessively small, the contact surface pressure by the repeated load P is excessively large, resulting in a decrease in the durability of the snap ring 14.

In the above description, the problem and the structure for solving the problem have been described for the snap ring 14 disposed on the distal end side of the foot shaft 32, but the same problem occurs for the snap ring 15 disposed on the root side of the foot shaft 32, and therefore the structure described above can be similarly applied to the snap ring 15.

The embodiment of the present invention described above can be applied to a tripod type constant velocity universal joint having a double row roller type with another structure.

For example, the outer peripheral surface of the foot shaft 32 may be formed into a convex curved surface (for example, a convex circular arc shape in cross section), and the inner peripheral surface 12a of the inner ring 12 may be formed into a cylindrical surface. The outer peripheral surface of the foot shaft 32 may be formed into a convex curved surface (for example, a convex circular arc shape in cross section), and the inner peripheral surface 12a of the inner ring 12 may be formed into a concave spherical surface fitted to the outer peripheral surface of the foot shaft. In this case, the eave may be provided at least at one of the both end portions of the outer ring, and thus, the clasps 14 and 15 at either end portion may not be required.

The tripod type constant velocity universal joint 1 described above is not limited to application to a drive shaft of a motor vehicle, and can be widely used for a power transmission path of a motor vehicle, industrial equipment, or the like.

Description of the reference numerals

1. Tripod constant velocity universal joint

2. Outer coupling member

3. Tripod member

4. Roller unit

5. Raceway groove

6. Roller guide surface

11. Roller (outer ring)

12. Inner ring

13. Needle roller

14. Restriction component (clasp)

15. Restriction component (clasp)

31. Main body part

32. A foot shaft.

Claims (5)

1. A tripod constant velocity universal joint, comprising:

An outer joint member having, at three locations in the circumferential direction, track grooves extending in the joint axial direction, each track groove having a pair of roller guide surfaces disposed opposite each other in the joint circumferential direction;

A tripod member including a main body portion having a center hole and three leg shafts protruding in a radial direction of the main body portion;

a roller fitted to each of the leg shafts; and

An inner ring which is externally fitted to the foot shaft and rotatably supports the roller,

The rollers are movable in the axial direction of the outer joint member along the roller guide surfaces,

The rollers and the inner race form a roller unit capable of swinging relative to the footshaft,

A regulating member for regulating movement of the inner race in the axial direction of the foothold is provided on the inner periphery of the roller, and the regulating member is fitted into a mounting groove formed on the inner peripheral surface of the roller,

The tripod type constant velocity universal joint is characterized in that,

The regulating member has an annular shape with an end capable of elastically reducing diameter and is provided with a slit extending in a direction inclined relative to the radial direction of the regulating member, and the outer diameter dimension of the regulating member is D, the width dimension is b, and the thickness is t, so that 7.4 < D/b < 9.8 and 2.8 < b/t < 4.6 are satisfied.

2. The tripod type constant velocity universal joint according to claim 1, wherein,

The restricting member is capable of elastically reducing the diameter to a diameter smaller than the inner diameter of the roller by overlapping both ends.

3. The tripod type constant velocity universal joint according to claim 1 or 2, wherein,

The inner peripheral surface of the inner ring is formed in an arcuate convex surface in a longitudinal section of the ring, the outer peripheral surface of the footshaft is in a straight shape in a longitudinal section including an axis of the footshaft and in a substantially elliptical shape in a cross section orthogonal to the axis of the footshaft, and the outer peripheral surface of the footshaft abuts against the inner peripheral surface of the inner ring in a direction orthogonal to an axis of the coupling and forms a gap with the inner peripheral surface of the ring in an axis direction of the coupling.

4. The tripod constant velocity universal joint according to any one of claims 1 to 3, wherein,

A plurality of rolling elements are disposed between the inner race and the rollers.

5. The tripod type constant velocity universal joint according to claim 4, wherein,

The rolling bodies are rolling pins.