WO2023189123A1

WO2023189123A1 - Tripod-type constant-velocity universal joint

Info

Publication number: WO2023189123A1
Application number: PCT/JP2023/007433
Authority: WO
Inventors: 卓板垣; 達朗杉山; 将太河田
Original assignee: Ntn株式会社
Priority date: 2022-03-28
Filing date: 2023-02-28
Publication date: 2023-10-05
Also published as: JP2023144585A

Abstract

A snap ring 14 has a cut surface A obtained by shearing. The cut surface A has a shear surface A2 that is provided in a region on the front surface 14d side and a fracture surface A3 that is provided in a region on the back surface 14e side. The front surface 14d of the snap ring14 faces a plurality of needle rollers 13.

Description

Tripod type constant velocity universal joint

The present invention relates to a tripod type constant velocity universal joint.

In drive shafts used in automobile power transmission systems, 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 sliding constant velocity universal joint is connected to the outboard side (outside in the vehicle width direction). A fixed constant velocity universal joint is often combined with a fixed type constant velocity universal joint. The sliding type constant velocity universal joint referred to here allows both angular displacement and axial relative movement between two axes, while the fixed type constant velocity universal joint allows angular displacement between two axes. However, relative movement in the axial direction between the two axes is not permitted.

A tripod type constant velocity universal joint is known as a sliding type constant velocity universal joint. As this tripod type constant velocity universal joint, there are a single roller type and a double roller type. 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 that is inserted into a track groove of an outer joint member, and an inner ring that is fitted onto the leg shaft of a tripod member and rotatably supports the roller. The double roller type allows the roller to swing relative to the leg axis, so it reduces induced thrust (axial force induced by friction between parts inside the joint) and sliding resistance compared to the single roller type. It has the advantage that it can be reduced.

An example of a double roller type tripod constant velocity universal joint is disclosed in Patent Document 1 below. In such a double roller type tripod type constant velocity universal joint, the rollers are rotatably arranged on the outer periphery of the inner ring via needle rollers. The needle roller and inner ring are prevented from coming off 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 circumferential surface of the roller and spaced apart in the leg axis direction at an interval corresponding to the length of the needle roller, and snap rings are fitted into the respective mounting grooves.

The snap ring has an end shape with a slit at one location in the circumferential direction, and is attached to a mounting groove on the inner circumferential surface of the roller while being elastically reduced in diameter. In Patent Document 2 listed below, the circumferential ends of the snap rings are chamfered to prevent the circumferential ends of the snap rings from interfering with each other when the snap rings are attached to the inner peripheral surface of the roller.

Japanese Patent Application Publication No. 2000-320563 Japanese Patent Application Publication No. 2007-10086

Snap rings are often formed by shearing (press molding). Generally, the shearing process is performed by punching the metal plate 100 using a die 201 and a punch 202, as shown in FIGS. 10 to 13. Specifically, by lowering the punch 202 and making it bite into the metal plate 100, a sag 101 is formed on the metal plate 100 (see FIG. 10). Thereafter, by further lowering the punch 202, a sheared surface 102 is formed in the metal plate 100 and a crack 103a is generated (see FIG. 11). By further lowering the punch 202, the cracks 103a are connected to form a fracture surface 103 (see FIG. 12), and the metal plate 100 is divided into a product portion 100A and a scrap portion 100B (see FIG. 13).

As shown in FIG. 4, the cut surface of the product part 100A thus formed has a sag 101 and a groove from one side in the thickness direction (upper side in the figure) to the other side in the thickness direction (lower side in the figure). A cross section 102 and a fractured surface 103 are formed in this order. A burr (also called burr) 104 that protrudes downward in the figure is formed at the lower end of the fracture surface 103 in the figure.

When a snap ring is formed by shearing, a burr is formed at the end of the cut surface (inner peripheral surface, outer peripheral surface, and end surfaces facing each other through the slit) on the fracture surface side. When transmitting torque with a tripod type constant velocity universal joint, the snap ring slides on the end face of the needle roller while the roller unit (roller, inner ring, and needle roller integrated with the snap ring) Rotate about the leg axis. At this time, if a burr is formed on the snap ring, the burr interferes with the end surface of the needle roller, inhibiting the rotation of the roller unit, deteriorating the vibration characteristics of the constant velocity universal joint, and reducing the durability of the roller unit. This may lead to a decline.

Therefore, an object of the present invention is to prevent deterioration of the vibration characteristics of a double roller type tripod type constant velocity universal joint and a decrease in durability of the roller unit.

In order to solve the above problems, the present invention provides an outer joint member in which track grooves extending in the axial direction are formed at three locations in the circumferential direction of the inner peripheral surface, and a track groove arranged on the inner circumference of the outer joint member, A tripod member having three leg shafts protruding radially toward the groove, and three roller units rotatably supported by the leg shafts and housed in the track groove,
The roller unit includes a roller, an inner ring fitted onto the leg shaft, a plurality of rolling elements disposed between an inner circumferential surface of the roller and an outer circumferential surface of the inner ring, and an inner ring of the roller. A tripod type constant velocity universal joint having a snap ring attached to a mounting groove formed on a peripheral surface and regulating movement of the inner ring and the leg shafts of the plurality of rolling elements in the axial direction,
The snap ring has a cut surface formed by shearing,
The cut surface has a sheared surface provided in a region on one side in the thickness direction and a fractured surface provided in a region on the other side in the thickness direction,
One surface of the snap ring in the thickness direction faces the plurality of rolling elements.

In this way, in the present invention, one surface of the snap ring in the thickness direction (i.e., the shear surface side) faces the rolling element, and the surface of the snap ring on the other side in the thickness direction (i.e., the fracture surface side) is arranged to face the rolling element. Placed on the opposite side from the rolling element. As a result, the burrs formed at the end of the cut surface of the snap ring on the fracture surface side are placed on the opposite side of the rolling elements (for example, needle rollers), thereby preventing the burrs from interfering with the rolling elements. It can be avoided.

For example, the snap ring has an end shape with a slit at one location in the circumferential direction, and this slit can be inclined with respect to the radial direction of the snap ring. In this case, the punching direction of the snap ring, that is, the front and back sides of the snap ring (which side is the sheared surface side) can be recognized by the inclination direction of the slit. Therefore, when the snap ring is installed in the mounting groove of the roller, the front and back sides of the snap ring can be easily confirmed by the inclined direction of the slit.

In the above tripod type constant velocity universal joint, the inner circumferential surface of the inner ring has an arcuate convex surface that is convex toward the inner diameter side in a cross section including the axis of the inner ring, and the outer circumferential surface of the leg shaft has In a cross section including the axis of the leg shaft, the leg shaft has a straight shape parallel to the axis, and in a cross section orthogonal to the axis of the leg shaft, it has a substantially elliptical shape, and the outer circumferential surface of the leg shaft is parallel to the axis in the torque load direction. It can be configured such that it comes into contact with the inner circumferential surface of the inner ring, and a gap is formed between the inner circumferential surface of the inner ring and the inner circumferential surface of the inner ring in the joint axial direction.

As described above, according to the present invention, it is possible to avoid interference between the burrs formed on the snap ring and the rolling elements, so it is possible to prevent deterioration of vibration characteristics and decrease in durability of the roller unit.

FIG. 2 is a cross-sectional view in the joint axial direction showing a double roller type tripod constant velocity universal joint. 2 is a sectional view taken along line KK in FIG. 1. FIG. FIG. 2 is a cross-sectional view taken along line LL in FIG. 1. FIG. FIG. 2 is a sectional view showing a state in which the tripod type constant velocity universal joint of FIG. 1 assumes an operating angle. FIG. 3 is a plan view of the roller unit attached to the leg shaft, seen from the direction A in FIG. 2; FIG. 3 is a cross-sectional view of the roller unit along the axial direction of the leg shaft. It is a top view of a snap ring. FIG. 3 is a perspective view of a cut surface of the snap ring. 8 is a cross-sectional view of the roller unit taken along line MM in FIG. 7. FIG. FIG. 3 is a cross-sectional view showing the procedure of shearing. FIG. 3 is a cross-sectional view showing the procedure of shearing. FIG. 3 is a cross-sectional view showing the procedure of shearing. FIG. 3 is a cross-sectional view showing the procedure of shearing. FIG. 3 is a cross-sectional view of a cut surface obtained by shearing.

An embodiment of a tripod type constant velocity universal joint according to an embodiment of the present invention will be described based on the drawings.

The tripod type constant velocity universal joint 1 of this embodiment shown in FIGS. 1 to 4 is a double roller type. In the following description, the axial direction of the joint and the circumferential direction of the joint mean the axial direction and the circumferential direction of the tripod constant velocity universal joint when the operating angle is 0°, respectively.

As shown in FIGS. 1 and 2, this 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 track groove 5 is provided with a roller guide surface 6 that is disposed opposite to 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 inside the outer joint member 2.

The tripod member 3 includes a body portion 31 (trunnion body portion) having a center hole 30, and three leg shafts 32 (trunnion body portions) that protrude in the radial direction from three equal parts in the joint circumferential direction on the outer peripheral surface of the body portion 31. journal). The tripod member 3 is coupled to the shaft 8 so that torque can be transmitted by fitting the male spline 81 formed on the shaft 8 as an axis into the female spline 34 formed in the center hole 30 of the body 31. . The end surface of the tripod member 3 on one side in the axial direction of the joint 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 axial direction of the joint. 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 that is an annular roller centered on the axis of the leg shaft 32, and an annular inner ring 12 that is arranged on the inner periphery of the outer ring 11 and fitted onto the leg shaft 32. , a large number of rolling elements 13 interposed between an outer ring 11 and an inner ring 12. In this embodiment, as an example of the rolling elements 13, full-roller needle rollers without a cage are used. The roller unit 4 is accommodated in the track groove 5 of the outer joint member 2. The roller unit 4 made up of the outer ring 11, the inner ring 12, and the needle rollers 13 has a structure that does not naturally disassemble due to the pair of snap rings 14, as will be described in detail later.

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

The needle rollers 13 have the cylindrical inner circumferential surface of the outer ring 11 as an outer raceway surface, the cylindrical outer circumferential surface of the inner ring 12 as an inner raceway surface, and can freely roll between these outer raceway surfaces and inner raceway surfaces. will be placed in

The outer peripheral surface of each leg shaft 32 of the tripod member 3 has a straight shape parallel to the axis 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 the torque load 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 joint axial direction, that is, in the direction of the short axis b.

The inner circumferential surface 12a of the inner ring 12 has a convex arc shape in any cross section including the axis of the inner ring 12. Because of this and because the cross-sectional shape of the leg shaft 32 is approximately elliptical as described above, and a predetermined gap m is provided between the leg shaft 32 and the inner ring 12, the inner ring 12 It becomes possible to swing with respect to 32. As described above, since the inner ring 12 and the outer ring 11 are assembled as a relatively rotatable assembly via the needle rollers 13, the outer ring 11 can swing together with the inner ring 12 with respect to the leg shaft 32. It is. That is, the axes of the outer ring 11 and the inner ring 12 can be inclined 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 is swingable. Therefore, it is possible to avoid a situation where the outer ring 11 and the roller guide surface 6 are obliquely crossed. As a result, the outer ring 11 rolls horizontally with respect to the roller guide surface 6, so that induced thrust and sliding resistance can be reduced, and the vibration of the tripod type constant velocity universal joint 1 can be reduced. can.

Furthermore, as already mentioned, the cross section (transverse section) of the leg shaft 32 is approximately elliptical, and the cross section (vertical section) of the inner circumferential surface 12a of the inner ring 12 is an arcuate convex cross section. As shown, the outer circumferential surface of the leg shaft 32 and the inner circumferential surface 12a of the inner ring 12 on the torque load side make point contact (including cases where they contact in a narrow area close to point contact) at a contact point X. . Therefore, the force that tends to tilt 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 viewed from the 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.

As shown in FIG. 6, in the roller unit 4, a pair of mounting grooves 11a are provided on the inner peripheral surface of the outer ring 11, spaced apart in the axial direction of the leg shaft 32. The pair of snap rings 14 are attached to the inner circumferential surface 11b of the outer ring 11 spaced apart in the axial direction of the leg shaft 32 by fitting into the respective attachment grooves 11a. The snap ring 14 faces end surfaces of the needle roller 13 and the inner ring 12 on both sides of the leg shaft 32 in the axial direction. Relative movement of the needle rollers 13 and the leg shafts 32 of the inner ring 12 in the axial direction with respect to the outer ring 11 is regulated by a pair of snap rings 14 . Therefore, natural disassembly of the roller unit 4 is restricted by the pair of snap rings 14.

As shown in FIG. 7, the snap ring 14 has a slit C (circumferential gap) at one location in the circumferential direction, and is formed into an end ring shape separated by the slit C. The snap ring 14 has a shape in which a band plate having a rectangular cross section is wound around an axis extending in the thickness direction of the band plate. The slit C extends in a direction oblique to the radial direction of the snap ring 14.

The slit C of the snap ring 14 is formed by shearing, and is generally formed by punching a metal material (for example, a steel plate) with a die and a punch (see FIGS. 10 to 13). The edge of the flat snap ring 14, specifically, the circumferentially opposite ends 14c of the snap ring 14 (the end faces facing each other in the circumferential direction via the slit C) are provided with a cut surface A by shearing. Depending on the processing method, the cut surface A may also be provided on the inner circumferential surface 14a and the outer circumferential surface 14b of the snap ring 14. As shown in FIG. 8, these cut surfaces A include a surface from one side in the thickness direction (hereinafter referred to as the "front surface 14d") to a surface on the other side in the thickness direction (hereinafter referred to as the "back surface 14e"). ), a sag A1, a sheared surface A2, a fractured surface A3, and a burr A4 are formed in this order. The sag A1 is a curved surface having a substantially arc-shaped cross section that smoothly connects the surface 14d of the snap ring 14 and the sheared surface A2. The sheared surface A2 is a flat surface substantially parallel to the shearing direction (thickness direction), is shiny, and has fine streaks in the shearing direction. The fractured surface A3 is a rough surface with more unevenness than the sheared surface A2. The burr A4 consists of a projection protruding from the back surface 14e of the snap ring 14.

As shown in FIG. 6, the outer diameter end of the snap ring 14 fits into the mounting groove 11a of the outer ring 11, and the inner diameter end of the snap ring 14 contacts the end surface of the inner ring 12 from the axial direction of the leg shaft 32. A radially intermediate portion of the snap ring 14 (a region excluding the outer diameter end and the inner diameter end) contacts the end surface of the needle roller 13 from the axial direction of the leg shaft 32. When the constant velocity universal joint 1 rotates, the roller unit 4 rotates around the leg shaft 32 while the radially intermediate portion of the snap ring 14 and the end surface of the needle roller 13 slide. At this time, if the back surface 14e of the snap ring 14 (the surface from which the burr A4 protrudes) faces the end surface of the needle rollers 13, the needle rollers 13 (indicated by dotted lines in FIG. 7) ) slides across the slit C of the snap ring 14, there is a risk that the burr A4 provided at the circumferential end 14c of the snap ring 14 and the needle roller 13 may interfere with each other.

Therefore, in this embodiment, as shown in FIG. 9, the front surface 14d of the snap ring 14 (the surface from which the burr A4 does not protrude) is made to face the end surface of the needle roller 13, and the back surface 14e from which the burr A4 protrudes is arranged in a needle-like shape. It is arranged on the opposite side from roller 13. As a result, when the needle rollers 13 and the snap ring 14 slide during rotation of the constant velocity universal joint 1, the burr A4 of the snap ring 14 does not interfere with the needle rollers 13, so the tripod type constant velocity It is possible to prevent deterioration of the vibration characteristics of the universal joint and deterioration of the durability of the roller unit.

Here, the method of assembling the roller unit 4 will be explained. The roller unit 4 includes an inner ring 12 disposed on the inner periphery of an outer ring 11, and a large number of needle rollers 13 disposed between these in a full roller state. It can be assembled by attaching.

In this embodiment, before attaching the snap ring 14 to the mounting groove 11a on the inner peripheral surface of the outer ring 11, the front and back sides of the snap ring 14 are checked. Since the sheared surface A2 and the fractured surface A3 have different surface properties, it is also possible to confirm the front and back sides of the snap ring 14 by visually checking the cut surface A. However, since the area of the cut surface A is small, visual confirmation as described above is not easy, takes time, and is prone to mistakes.

Therefore, in this embodiment, the front and back sides of the snap ring 14 are confirmed by the inclination direction of the slit C of the snap ring 14. That is, the inclination direction of the slit C is different when the snap ring 14 is viewed from the front surface 14d side (sheared surface A2 side) and when viewed from the back surface 14e side (fractured surface A3 side). Specifically, when the snap ring 14 is viewed from the back surface 14e side, the slit C is inclined to one side in the circumferential direction with respect to the radial direction (see FIG. 7), and when the snap ring 14 is viewed from the surface 14d side, the slit C is inclined to one side in the circumferential direction with respect to the radial direction (see FIG. 7). It is inclined toward the other side in the circumferential direction (the opposite side to FIG. 7) with respect to the radial direction. Therefore, as shown in FIGS. 5 and 7, when the snap ring 14 is viewed from the axial direction, if the slit C is inclined to one side in the circumferential direction with respect to the radial direction, the front surface is the back surface 14e ( It can be confirmed that the surface on the side of the fracture surface A3) is the surface 14d (the surface on the side of the sheared surface A2), and the surface on the back side is the surface 14d (the surface on the side of the sheared surface A2). In this way, depending on the direction of inclination of the slit C, it is possible to easily check the front and back sides of the snap ring 14. The inclination direction of the slit C may be checked visually by an operator, or automatically by an assembly device.

After confirming the front and back sides of the snap ring 14, the snap ring 14 is installed in the mounting groove 11a of the outer ring 11 in a predetermined direction (see FIG. 9). In this embodiment, as shown in FIG. 5, the snap ring 14 is attached to the mounting groove 11a of the outer ring 11 with the slit C inclined toward one side in the circumferential direction when the roller unit 4 is viewed from the outside in the axial direction. do. As a result, as shown in FIG. 9, the snap ring 14 is held in a state in which the front surface 14d of the snap ring 14 faces the needle rollers 13 and the back surface 14e of the snap ring 14 is disposed on the opposite side from the needle rollers 13. It can be assembled to the outer ring 11.

Note that in this embodiment, the pair of snap rings 14 have the same configuration (punched with the same mold). Therefore, no matter which side of the assembly the roller unit 4 is viewed from in the axial direction, the slit C of the snap ring 14 is inclined toward one side in the circumferential direction with respect to the radial direction (see FIG. 5).

The present invention is not limited to the above embodiments. For example, in the above embodiment, the snap ring 14 is arranged on both sides of the needle roller 13 in the axial direction, but by providing a collar on either end of the outer ring in the axial direction, one snap ring 14 can be disposed on both sides of the needle roller 13 in the axial direction. The ring 14 can also be omitted.

The embodiments of the present invention described above can also be applied to double roller type tripod 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 spherical surface), and the inner peripheral surface 12a of the inner ring 12 may be formed into a cylindrical surface. Alternatively, the outer circumferential surface of the leg shaft 32 may be formed into a convex curved surface (for example, a convex arc-shaped cross section), and the inner circumferential surface 12a of the inner ring 12 may be formed into a concave spherical surface that fits with the outer circumferential surface of the leg shaft.

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, etc.

1 Tripod type constant velocity universal joint 2 Outer joint member 3 Tripod member 4 Roller unit 5 Track groove 6 Roller guide surface 8 Shaft 11 Outer ring (roller)
11a Mounting groove 12 Inner ring 13 Needle roller (rolling element)
14 Snap ring 14c Circumferential end (end surface)

14d Front surface

14e Back surface 31 Body section 32 Leg shaft A Cut surface A1 Sag A2 Shear surface A3 Fracture surface A4 Burr C Slit

Claims

an outer joint member in which track grooves extending in the axial direction are formed at three locations in the circumferential direction of the inner peripheral surface;
a tripod member having three leg shafts disposed on the inner periphery of the outer joint member and protruding in a radial direction toward the track groove;
three roller units rotatably supported by the leg shaft and housed in the track groove;
The roller unit is
Laura and
an inner ring fitted onto the leg shaft;
a plurality of rolling elements arranged between the inner circumferential surface of the roller and the outer circumferential surface of the inner ring;
A tripod type constant velocity universal joint having a snap ring attached to a mounting groove formed on an inner circumferential surface of the roller and regulating movement of the inner ring and the leg shafts of the plurality of rolling elements in the axial direction. ,
The snap ring has a cut surface formed by shearing,
The cut surface has a sheared surface provided in a region on one side in the thickness direction and a fractured surface provided in a region on the other side in the thickness direction,
A tripod type constant velocity universal joint in which one surface of the snap ring in the thickness direction faces the plurality of rolling elements.
The snap ring has an end shape with a slit at one location in the circumferential direction,
The tripod type constant velocity universal joint according to claim 1, wherein the slit is inclined with respect to the radial direction of the snap ring.
The inner circumferential surface of the inner ring has an arc-shaped convex surface that is convex toward the inner diameter side in a cross section including the axis of the inner ring,
The outer circumferential surface of the leg shaft has a straight shape parallel to the axis in a cross section including the axis of the leg shaft, and has a substantially elliptical shape in a cross section perpendicular to the axis of the leg shaft,
According to claim 1 or 2, the outer circumferential surface of the leg shaft contacts the inner circumferential surface of the inner ring in the torque load direction, and a gap is formed between the outer circumferential surface of the leg shaft and the inner circumferential surface of the inner ring in the joint axis direction. The tripod type constant velocity universal joint described.
The tripod type constant velocity universal joint according to any one of claims 1 to 3, wherein the rolling elements are needle rollers.