WO2023047930A1

WO2023047930A1 - Tripod-type constant-velocity universal joint

Info

Publication number: WO2023047930A1
Application number: PCT/JP2022/033278
Authority: WO
Inventors: 卓板垣; 達朗杉山; 将太河田
Original assignee: Ntn株式会社
Priority date: 2021-09-24
Filing date: 2022-09-05
Publication date: 2023-03-30
Also published as: JP2023046774A; CN117957382A

Abstract

In a tripod-type constant-velocity universal joint 1 of a double-roller type, snap rings 14, 15 that restrict the movement of an inner ring 12 in the axial direction of a leg shaft 32 are provided on the inner periphery of an outer ring 11, and the snap rings 14, 15 engage with an attachment groove 11a that is formed in the inner peripheral surface of the outer ring 11. The snap rings 14, 15 have a slit C that extends in a direction which is inclined with respect to the radial direction thereof. The relationships 7.4<D/b<9.8 and 2.8<b/t<4.6 are established, where D, b, and t are respectively the outer diameter dimension, the width dimension, and the thickness of the snap rings 14, 15 before an elastic deformation.

Description

Tripod type constant velocity universal joint

The present invention relates to tripod-type constant velocity universal joints used for power transmission in automobiles and various industrial machines.

In the drive shaft used in the power transmission system of automobiles, a sliding constant velocity universal joint is connected to the inboard side (center side in the vehicle width direction) of the intermediate shaft, and the outboard side (end in the vehicle width direction) side) is often connected to a fixed constant velocity universal joint. The sliding constant velocity universal joint referred to here permits both angular displacement and axial relative movement between two axes, and the fixed constant velocity universal joint permits angular displacement between two axes. However, it does not allow relative axial movement between the two axes.

A tripod type constant velocity universal joint is known as a sliding constant velocity universal joint. There are a single roller type and a double roller type as this tripod type constant velocity universal joint. In the single roller type, a roller inserted into the track groove of the outer joint member is rotatably attached to the leg shaft of the tripod member via a plurality of needle rollers. The double roller type includes a roller inserted into the track groove of the outer joint member, and an inner ring that fits over the leg shaft of the tripod member and supports the roller rotatably. Since the double roller type allows the rollers to oscillate about the leg shaft, the induced thrust (axial force induced by friction between parts inside the joint) and sliding resistance are reduced compared to the single roller type. It has the advantage of being able to reduce each.

Patent Document 1 below discloses an example of a double roller type tripod type constant velocity universal joint. In such a double-roller tripod type constant velocity universal joint, rollers are rotatably arranged on the outer periphery of an inner ring via needle rollers. The needle roller and inner ring are retained by a pair of snap rings attached to the inner peripheral surface of the roller. That is, a pair of mounting grooves are formed on the inner peripheral surface of the roller and spaced apart in the leg axis direction at intervals corresponding to the length of the needle rollers, and snap rings are fitted in the respective mounting grooves.

JP-A-2000-320563

However, conventionally, when designing snap rings, no particular consideration has been given to achieving both workability and durability (strength) during installation. Specifically, regarding the snap ring mountability, the smaller the width dimension of the snap ring (the radial width dimension of the snap ring) relative to the diameter dimension of the snap ring, the greater the elasticity of the snap ring. Therefore, the assemblability is improved.

On the other hand, when the width dimension of the snap ring is reduced, the durability or strength of the snap ring is reduced. That is, the roller unit consisting of the rollers, inner rings, and needle rollers repeatedly slides against the leg shaft in the axial direction of the leg shaft while the joint is rotationally driven with a differential angle. , the snap ring attached to the inner peripheral surface of the roller is repeatedly loaded from the inner ring. If the width dimension of the snap ring is small, the contact area between the snap ring and the inner ring becomes small, and as a result, the contact surface pressure due to repeated loads increases, resulting in a decrease in the durability of the snap ring.

In this way, the verification by the present inventors revealed that snap ring mounting workability and durability (strength) are in a trade-off relationship in which one is increased and the other is decreased. Conventional snap rings are not designed with this relationship in mind, and do not have specifications that improve both mounting workability and durability (strength).

Therefore, an object of the present invention is to provide a tripod-type constant velocity universal joint that achieves both workability in attaching snap rings and durability or strength.

The present invention, which has been made based on the above findings, has track grooves extending in the axial direction of the joint at three locations in the circumferential direction, and each track groove has a pair of roller guide surfaces arranged opposite to each other in the circumferential direction of the joint. a tripod member having an outer joint member, a trunk portion having a center hole, three leg shafts projecting in the radial direction of the trunk portion, rollers attached to each of the leg shafts, and an outer and an inner ring that is fitted and rotatably supports the roller, the roller is movable along the roller guide surface in the axial direction of the outer joint member, and the roller and the inner ring A roller unit that can swing with respect to the leg shaft is configured, and a restricting member (snap ring) is provided on the inner circumference of the roller to restrict movement of the inner ring in the axial direction of the leg shaft, and the restricting member is fitted into the mounting groove formed on the inner peripheral surface of the roller, wherein the regulating member has a ring shape with ends that can be elastically contracted, and in the radial direction of the regulating member 7.4<D/b<9.8 and 2.8, where D is the outside diameter dimension, b is the width dimension, and t is the thickness of the regulation member. <b/t<4.6 is satisfied.

It is preferable that the regulating member can be elastically reduced in diameter until it becomes smaller than the inner diameter of the roller by overlapping both ends of the regulating member.

The inner peripheral surface of the inner ring is arcuately convex in the longitudinal section of the inner ring, and the outer peripheral surface of the leg shaft is straight in the longitudinal section including the axis of the leg shaft. The cross section perpendicular to the axis has a substantially elliptical shape, and the outer peripheral surface of the leg shaft contacts the inner peripheral surface of the inner ring in the direction perpendicular to the axis of the joint, and the inner ring in the axial direction of the joint. It is preferable that a gap is formed between the inner peripheral surface of the

It is preferable to arrange a plurality of rolling elements between the inner ring and the roller. Needle rollers, for example, can be used as the rolling elements.

According to the present invention, it is possible to provide a tripod-type constant velocity universal joint that achieves both workability in attaching snap rings and durability or strength.

FIG. 2 is a cross-sectional view in the joint axial direction showing a double roller type tripod constant velocity universal joint. FIG. 2 is a cross-sectional view taken along line KK of FIG. 1; FIG. 2 is a cross-sectional view taken along line LL of FIG. 1; FIG. 2 is a cross-sectional view showing a state in which the tripod-type constant velocity universal joint of FIG. 1 has an operating angle; FIG. 3 is a plan view of the roller unit attached to the leg shaft as viewed from direction A in FIG. 2 ; FIG. 4 is a cross-sectional view of the roller unit along the axial direction of the leg shaft; It is a figure which represented the attachment procedure of the snap ring of the leg shaft front-end|tip side to a roller unit in the cross section along the axial direction of a leg shaft. FIG. 4 is a plan view of a snap ring; FIG. 9 is a cross-sectional view taken along line MM of FIG. 8; FIG. 4 is a cross-sectional view along the axial direction of the leg shaft of the roller unit;

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

The tripod type constant velocity universal joint 1 of this embodiment shown in FIGS. 1 to 4 is of double roller type. 1 is an axial cross-sectional view of a double roller type tripod type constant velocity universal joint, and FIG. 2 is a cross-sectional view taken along line KK of FIG. 3 is a cross-sectional view taken along line LL in FIG. 1, and FIG. 4 is an axial cross-sectional view showing the tripod type constant velocity universal joint when the operating angle is taken. In the following description, the axial direction of the joint and the circumferential direction of the joint respectively mean the axial direction and the circumferential direction of the tripod type constant velocity universal joint when the operating angle is set to 0°.

As shown in FIGS. 1 and 2, this tripod type constant velocity universal joint 1 is mainly composed of an outer joint member 2, a tripod member 3 as an inner joint member, and a roller unit 4 as a torque transmission member. It is The outer joint member 2 has a cup shape with one end opened, and three linear track grooves 5 extending in the joint axial direction are formed on the inner peripheral surface at regular intervals in the joint circumferential direction. A roller guide surface 6 is formed in each track groove 5 so as to face each other in the joint circumferential direction of the outer joint member 2 and extend in the joint axial direction. A tripod member 3 and a roller unit 4 are housed inside the outer joint member 2 .

The tripod member 3 includes a body portion 31 (trunnion body portion) having a central hole 30 and three leg shafts 32 (trunnion shafts) protruding radially from trisecting positions in the joint circumferential direction of the outer peripheral surface of the body portion 31 (trunnion body portion). journal). The tripod member 3 is coupled to the shaft 8 so as to transmit torque by fitting a male spline 81 formed on the shaft 8 as an axis into a female spline 34 formed in the central hole 30 of the trunnion body 31 . be. The end surface of the tripod member 3 on one side in the joint axial direction is engaged with the shoulder portion 82 provided on the shaft 8, and the retaining ring 10 attached to the tip of the shaft 8 is engaged with the end surface of the tripod member 3 on the other side in the joint axial direction. By doing so, the tripod member 3 is fixed to the shaft 8 in the joint axial direction.

The roller unit 4 includes an outer ring 11, which is an annular roller centered on the axis of the leg shaft 32, and an annular inner ring 12, which is arranged on the inner diameter side of the outer ring 11 and fitted onto the leg shaft 32. , and a large number of rolling elements 13 interposed between the outer ring 11 and the inner ring 12 . In this embodiment, as an example of the rolling elements 13, needle rollers in a full complement state without a retainer are used. The roller unit 4 is housed in the track groove 5 of the outer joint member 2 . The roller unit 4 consisting of the outer ring 11, the inner ring 12 and the needle rollers 13 has a structure that does not naturally decompose due to

steel snap rings

14 and 15 as regulating members, as will be described later in detail. ing.

In this embodiment, the outer peripheral surface 11a (see FIG. 2) of the outer ring 11 is a convex curved surface whose generatrix is an arc having the center of curvature on the axis of the leg shaft 32. An outer peripheral surface 11 a of the outer ring 11 is in angular contact with the roller guide surface 6 .

The needle rollers 13 are free to roll between the outer raceway surface of the outer ring 11 and the inner raceway surface of the inner ring 12, respectively. placed in

The outer peripheral surface of each leg shaft 32 of the tripod member 3 has a straight shape in the axial direction of the leg shaft 32 in a cross section in any direction including the axis of the leg shaft 32 . Further, as shown in FIG. 3 , the outer peripheral surface of the leg shaft 32 has a substantially elliptical shape in a cross section perpendicular to the axis of the leg shaft 32 . The outer peripheral surface of the leg shaft 32 contacts the inner peripheral surface 12a of the inner ring 12 in a direction orthogonal to the joint axial direction, that is, in the direction of the long axis a. A gap m is formed between the outer peripheral surface of the leg shaft 32 and the inner peripheral surface 12a of the inner ring 12 in the direction of the joint axis, that is, the direction of the minor axis b.

As shown in FIGS. 1 and 2, the intermediate portion 33 between the trunk portion 31 of the tripod member 3 and the leg shaft 32 is formed to draw a concave curve in any cross section including the axis of the leg shaft 32.

The inner peripheral surface 12a of the inner ring 12 has a convex arc shape in any cross section including the axis of the inner ring 12. In addition to this, the cross-sectional shape of the leg shaft 32 is substantially elliptical as described above, and the predetermined gap m is provided between the leg shaft 32 and the inner ring 12. 32 can be swung. As described above, the inner ring 12 and the outer ring 11 are assembled to be relatively rotatable via the needle rollers 13, so that the outer ring 11 is integrated with the inner ring 12 and can swing with respect to the leg shaft 32. is. That is, the axes of the outer ring 11 and the inner ring 12 can be tilted with respect to the axis of the leg shaft 32 within a plane including the axis of the leg shaft 32 (see FIG. 4).

As shown in FIG. 4, when the tripod-type constant velocity universal joint 1 rotates at an 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. Therefore, it is possible to prevent the outer ring 11 and the roller guide surface 6 from obliquely crossing each other. As a result, the outer ring 11 rolls horizontally on the roller guide surface 6, so that the induced thrust and the slide resistance can be reduced, and the vibration of the tripod type constant velocity universal joint 1 can be reduced. can.

Further, as already described, the cross section (transverse 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 an arcuate convex cross section. As shown, the outer peripheral surface of the leg shaft 32 and the inner peripheral surface 12a of the inner ring 12 on the torque load side contact at the contact point X in a narrow area close to point contact or point contact. Therefore, the force that tends to incline the roller unit 4 is reduced, and the stability of the posture of the outer ring 11 is improved.

5 is a plan view of the roller unit 4 attached to the leg shaft 32 as viewed from direction A in FIG. 2, and FIG. 6 is a sectional view of the roller unit 4 along the axial direction of the leg shaft 32. FIG.

As shown in FIGS. 5 and 6 , in the roller unit 4 , mounting grooves 11 a are provided on the inner peripheral surface of the outer ring 11 so as to be spaced apart in the axial direction of the leg shaft 32 . The snap rings 14 and 15 are attached to the inner peripheral surface of the outer ring 11 so as to be spaced apart from each other in the axial direction of the leg shaft 32 by fitting them into the attachment grooves 11a. The snap rings 14 , 15 are opposed to the end surfaces of the needle rollers 13 and the inner ring 12 on both axial sides of the leg shaft 32 . relative movement in the axial direction is restricted by

snap rings

14 and 15 . Accordingly, natural disassembly of the roller unit 4 is restricted by the snap rings 14,15.

FIG. 7 is a cross-sectional view along the axial direction of the leg shaft 32 showing the procedure for attaching the snap ring 14 on the outer diameter side of the joint to the roller unit 4 . 8 is a plan view of the snap ring 14, and FIG. 9 is a cross-sectional view taken along line MM of FIG. FIG. 10 is a sectional view along the axial direction of the leg shaft 32 of the roller unit 4. As shown in FIG.

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

As shown in FIG. 7, the snap ring 14 is attached to the attachment groove 11a of the inner peripheral surface of the outer ring 11 in a state in which the outer ring 11, the inner ring 12, and the needle rollers 13 are assembled. Specifically, an external force is applied to the snap ring 14 in a direction in which both ends 21 and 22 approach each other so that the both ends 21 and 22 overlap each other, and the outer diameter dimension φD of the snap ring 14 (the diameter dimension in the natural state when no external force is applied) ) is equal to or less than the inner diameter φd of the outer ring 11, the snap ring 14 with the reduced diameter is inserted into the inner circumference of the outer ring 11, and then the snap ring 14 is released by releasing the external force. is elastically expanded and fitted into the mounting groove 11a, the mounting of the snap ring 14 is completed. The outer peripheral surface of the snap ring 14 after attachment contacts the groove bottom surface of the attachment groove 11a.

As will be described below, this embodiment is characterized in that the shape of the snap ring 14 is determined from the viewpoint of achieving both workability in attaching the snap ring 14 and durability or strength.

From the standpoint of ease of mounting the snap ring 14, it is preferable that the radial width dimension b (see FIGS. 8 and 9) of the snap ring 14 is as small as possible. The smaller the width dimension b, the smaller the cross-sectional area of the snap ring shown in FIG. Therefore, workability is improved when the snap ring 14 is attached to the attachment groove 11a. Similarly, the larger the outer diameter D of the snap ring 14, the easier it is to elastically deform the snap ring 14, so that the workability of attaching the snap ring 14 is improved.

From the above verification results, it is considered that the ease of elastic deformation of the snap ring 14, that is, the mounting workability can be evaluated from the value of D/b. If the value of D/b is too small, it becomes difficult for the snap ring 14 to elastically deform, and the mounting workability decreases. On the other hand, if the value of D/b is too large, the snap ring 14 becomes large in its radial direction, which goes against the demand for compactness 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 the durability of the snap ring 14, the larger the radial width dimension b (see FIGS. 8 and 9) of the snap ring 14, the better. As shown in FIG. 10, the roller unit 4 consisting of the outer ring 11, the inner ring 12, and the needle rollers 13 rotates the leg shaft 32 with respect to the leg shaft 32 while the joint is rotationally driven with a differential angle. It slides repeatedly in the axial direction (vertical direction in the figure), and at that time, the snap ring 14 is repeatedly subjected to a load P from the inner ring 12 (in FIG. 10, the snap ring 15 at the base of the leg shaft is shown). However, the repeated load P similarly acts on the snap ring 14 on the tip end side of the leg shaft). If 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 will be small. result in loss of flexibility or strength.

Also, 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 will be reduced. Conversely, if the thickness t of the snap ring 14 is too large, the axial dimension of the leg shaft 32 of the roller unit 4 is increased.

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. If the value of b/t is too small, the durability or strength of the snap ring 14 will be reduced. it gets harder. From the above point of view, 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, the mounting workability and durability of the snap ring 14 can be improved. It can be compatible with strength. These characteristics are in a trade-off relationship with the width dimension b of the snap ring 14, and a design that emphasizes one characteristic lowers the other characteristic. In addition to dimension b, by devising parameters that take into account other dimension specifications (D and t) and setting the optimum range of values for both D/b and b/t, installation workability and durability can be improved. It is characterized by finding out that it can be compatible with 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 and the outer diameter dimension φD of the snap ring 14 is set to 0.5. It is preferable to set in the range of 005<S/D<0.035. If the S/D value is too large, the roller unit 4 becomes large in the radial direction of the axis of the leg shaft 32, and if the S/D value is too small, the contact surface pressure due to the repeated load P becomes excessive, resulting in snapping. This causes deterioration in durability of the ring 14 .

In the above description, the problem and the structure for solving the problem of the snap ring 14 arranged on the distal end side of the leg shaft 32 were explained, but the same problem also occurs with the snap ring 15 arranged on the root side of the leg shaft 32. , the snap ring 15 can be similarly applied to the configuration already described.

The embodiments of the present invention described above can also be applied to double roller type tripod type constant velocity universal joints having other configurations.

For example, the outer peripheral surface of the leg shaft 32 may be formed into a convex curved surface (for example, a convex circular cross section), and the inner peripheral surface 12a of the inner ring 12 may be formed into a cylindrical surface. Alternatively, the outer peripheral surface of the leg shaft 32 may be formed into a convex curved surface (for example, a convex arcuate cross section), and the inner peripheral surface 12a of the inner ring 12 may be formed into a concave spherical surface that fits with the outer peripheral surface of the leg shaft. At this time, at least one of the two end portions of the outer ring may be provided with a flange so that either one of the snap rings 14, 15 may be dispensed with.

The tripod type constant velocity universal joint 1 described above is not limited to application to drive shafts of automobiles, but can be widely used in power transmission paths of automobiles, industrial equipment, and the like.

1 tripod type constant velocity universal joint 2 outer joint member 3 tripod member 4 roller unit 5 track groove 6 roller guide surface 11 roller (outer ring)
12 inner ring 13 needle roller 14 restricting member (snap ring)
15 Regulating member (snap ring)
31 torso 32 leg shaft

Claims

an outer joint member having track grooves extending in the axial direction of the joint at three locations in the circumferential direction, each track groove having a pair of roller guide surfaces arranged to face each other in the circumferential direction of the joint;
a tripod member having a body portion having a center hole and three leg shafts projecting radially from the body portion;
a roller mounted on each leg shaft;
an inner ring fitted on the leg shaft and rotatably supporting the roller;
the roller is movable in the axial direction of the outer joint member along the roller guide surface;
The roller and the inner ring constitute a roller unit that can swing with respect to the leg shaft,
A tripod type or the like in which a restricting member is provided on the inner circumference of the roller to restrict movement of the inner ring in the axial direction of the leg shaft, and the restricting member is fitted into a mounting groove formed on the inner peripheral surface of the roller. In quick universal joints,
The regulating member has a ring shape with ends that can be elastically reduced in diameter, and has a slit extending in a direction inclined with respect to the radial direction of the regulating member, wherein the outer diameter dimension of the regulating member is D, and the width is A tripod type constant velocity universal joint characterized by satisfying 7.4<D/b<9.8 and 2.8<b/t<4.6 where b is a dimension and t is a thickness.
The tripod type constant velocity universal joint according to claim 1, wherein the regulation member can be elastically reduced in diameter until it becomes smaller in diameter than the inner diameter dimension of the roller by overlapping both ends.
The inner peripheral surface of the inner ring is arcuately convex in the longitudinal section of the ring, and the outer peripheral surface of the leg shaft is straight in the longitudinal section including the axis of the leg and the axis of the leg. The outer peripheral surface of the leg shaft contacts the inner peripheral surface of the inner ring in the direction perpendicular to the axis of the joint, and the inner peripheral surface of the ring in the axial direction of the joint. 3. The tripod type constant velocity universal joint according to claim 1, wherein a clearance is formed between the tripod type constant velocity universal joint and the peripheral surface.
The tripod type constant velocity universal joint according to any one of claims 1 to 3, wherein a plurality of rolling elements are arranged between the inner ring and the roller.
The tripod type constant velocity universal joint according to claim 4, wherein the rolling elements are needle rollers.