JP2023077101A - Tripod constant velocity universal joint - Google Patents

Abstract

To suppress the wear of a slide-contact portion between a leg shaft and an inner ring, in a double-roller tripod constant velocity universal joint.SOLUTION: In a double-roller tripod constant velocity universal joint 1, roller guide faces 6 of an outer ring 11 of a roller unit 4 and an outside joint member 2 are made to contact with each other at two points at a joint outside-diameter side and a joint inside-diameter side. In the roller guide faces 6, when RA denotes a curvature radius of a roller guide face 6a at the joint outside-diameter side, RB denotes a curvature radius of a roller guide face 6b at the joint inside-diameter side, and RD denotes a curvature radius of a roller external peripheral face, the RA, RB and RD are set in such a way as to satisfy inequation RA/RD<RB/RD.SELECTED DRAWING: Figure 5

Description

TECHNICAL FIELD The present invention relates to a tripod type constant velocity universal joint 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. A single roller type and a double roller type exist 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 rollers accommodated in track grooves of an outer joint member, and an inner ring that fits over the leg shafts of the tripod members and supports the rollers 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.

As a double roller type tripod constant velocity universal joint, as described in Patent Document 1 and Patent Document 2 below, the inner peripheral surface of the inner ring is formed into an arc-shaped convex cross section, and the outer peripheral surface of the leg shaft is It has a straight shape in the longitudinal section, and in the transverse section, it contacts the inner peripheral surface of the inner ring in the direction orthogonal to the axis of the joint, and there is a gap between it and the inner peripheral surface of the inner ring in the axial direction of the joint. known to have formed.

In the tripod-type constant velocity universal joint of Patent Document 1, the outer peripheral surface of the roller is a convex curved surface whose generatrix is an arc having the center of curvature at a position radially away from the axis of the leg shaft, and the roller guide surface of the track groove is It has a Gothic arch shape. In the tripod type constant velocity universal joint of Patent Document 2, the outer peripheral surface of the roller is formed into a partially spherical shape with the center of curvature on the axis of the leg shaft, and the roller guide surface of the track groove is formed into a cylindrical surface parallel to the joint axis. and In the former, the roller and the roller guide surface are in two-point contact (angular contact), and in the latter, the roller and the roller guide surface are in one-point contact (circular contact) or two-point contact (angular contact).

JP-A-2000-320563 Japanese Unexamined Patent Application Publication No. 2001-132766

In the double-roller type tripod constant velocity universal joints disclosed in Patent Documents 1 and 2, the inner ring swings relatively to the leg shaft during torque transmission, causing the axis of the leg shaft and the inner ring to oscillate relative to each other. changes the angle between the axes of As a result, repeated slippage occurs between the outer peripheral surface of the axle and the inner peripheral surface of the inner ring, and wear of the sliding contact portion (especially wear of the outer peripheral surface of the axle) is likely to occur. If the outer peripheral surface of the leg shaft is easily worn, the durability of the joint is reduced.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a double roller type tripod constant velocity universal joint in which wear is suppressed in sliding contact portions between the leg shaft and the inner ring.

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. 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 accommodated in the respective track grooves, 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 In a tripod type constant velocity universal joint that comprises a roller unit that can swing with respect to a leg shaft, and that the roller and the roller guide surface are in contact at two points on the joint outer diameter side and the joint inner diameter side, the roller guide Among the surfaces, RA/RD<RB/RD, where RA is the radius of curvature of the roller guide surface on the outer diameter side of the joint, RB is the radius of curvature of the roller guide surface on the inner diameter side of the joint, and RD is the radius of curvature of the outer peripheral surface of the roller. It is characterized by

With this configuration, during torque transmission, the amount of elastic deformation of the roller guide surface on the inner diameter side becomes larger than the amount of elastic deformation of the roller guide surface on the outer diameter side, so that the roller unit swings and the area on the torque load side moves to the outer diameter side of the joint. Therefore, the gap between the inner peripheral surface of the inner ring and the outer peripheral surface of the leg shaft can be increased on the inner diameter side. In this case, since the amount of lubricant retained in the gap increases, the centrifugal force can supply abundant lubricant to the contact area between the outer peripheral surface of the leg axle and the inner peripheral surface of the inner ring. It is possible to suppress the wear of

In this tripod type constant velocity universal joint, the inner peripheral surface of the inner ring is formed into an arc-shaped convex surface 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 shaft. and is substantially elliptical in a cross section perpendicular to the axis of the leg shaft, and the outer peripheral surface of the leg shaft abuts the inner peripheral surface of the inner ring in a direction perpendicular to the axis of the joint. Preferably, a clearance is formed between the ring and the inner peripheral surface of the ring in the axial direction of the joint.

Alternatively, the inner peripheral surface of the inner ring may be cylindrical, and the outer peripheral surface of the leg shaft may be spherical.

A plurality of rolling elements are preferably arranged between the inner ring and the roller. Needle rollers, for example, can be used as the rolling elements.

ADVANTAGE OF THE INVENTION According to this invention, in a double roller type tripod type constant velocity universal joint, it is possible to suppress wear at the sliding contact portion between the leg shaft and the inner ring.

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 in the joint axial direction showing a state in which the tripod type constant velocity universal joint of FIG. 1 has an operating angle; 3 is an enlarged sectional view showing a roller unit of the tripod type constant velocity universal joint shown in FIG. 2 and its peripheral structure; FIG. 3 is an enlarged sectional view showing a roller unit of the tripod type constant velocity universal joint shown in FIG. 2 and its peripheral structure; FIG. 3 is an enlarged sectional view showing a roller unit of the tripod type constant velocity universal joint shown in FIG. 2 and its peripheral structure; FIG. FIG. 5 is a diagram showing the results of measurement of the wear amount of the leg axles of the product of the present invention and the comparative product. FIG. 4 is a cross-sectional view showing another embodiment of a tripod-type constant velocity universal joint;

An embodiment of a tripod type constant velocity universal joint according to the present invention will be described with reference to FIGS. 1 to 9. FIG.

1 to 4 show a double roller tripod constant velocity universal joint according to the present embodiment. 1 is a cross-sectional view in the axial direction of the 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 a cross-sectional view along the axial direction of the tripod-type constant velocity universal joint with operating angles. In the following description, the axial direction of the joint, the radial direction of the joint, and the circumferential direction of the joint refer to the axial direction, the radial direction, and the circumferential direction of the tripod type constant velocity universal joint when the operating angle is set to 0°. Each means direction.

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 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 protrudes outward in the joint radial direction (outer diameter side) from a trunk portion 31 (trunnion trunk portion) having a central hole 30 and a trisecting position of the outer circumferential surface of the trunk portion 31 in the joint circumferential direction. It integrally has three leg shafts 32 (trunnion journals). 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 center 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 disassemble due to snap rings 14 and 15 attached to the inner peripheral surface of the outer ring 11. As shown in FIG.

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 32 a 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 32a of the leg shaft 32 has a substantially elliptical shape in a cross section orthogonal to the axis of the leg shaft 32. As shown in FIG. The outer peripheral surface 32a 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 32a 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.

An 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. As shown in FIG. 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 can swing integrally with the inner ring 12 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 are in point contact at the contact point X (including contact in a narrow area close to 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 to 7 are enlarged sectional views showing the roller unit 4 shown in FIG. 2 and its peripheral structure.

As shown in FIG. 5, in the present embodiment, the outer peripheral surface 11a of the outer ring 11 has a center of curvature O on the intersection of the axis PP of the leg shaft 32 and the centerline QQ of the roller unit 4 in the width direction. It is formed in a partially spherical shape with a The outer peripheral surface 11a of the outer ring 11 may be formed in an annular shape with the center of curvature on the center line QQ in the width direction of the roller unit 4 and not on the axis PP, instead of the partially spherical shape. can also

The roller guide surface 6 is formed in a Gothic arch shape combining two circular arcs in the cross section of the outer joint member 2 including the axis PP of the leg shaft 32 . Specifically, in the cross section, the roller guide surface 6 has a roller guide surface 6a on the outer diameter side of the center line QQ in the width direction of the roller unit 4, and a roller guide surface 6a on the inner diameter side of the center line QQ. It has a configuration in which it is connected to the roller guide surface 6b on the center line QQ in the width direction. Both the radius of curvature RA of the roller guide surface 6a on the outer diameter side and the radius of curvature RB of the roller guide surface 6b on the inner diameter side are larger than the radius of curvature RD of the outer peripheral surface 11a of the outer ring 11, RA>RD and RB>RD. is set to

The outer peripheral surface of the outer ring 11 and the roller guide surface 6 are in an angular contact state in which they are in contact at two points on the outer diameter side of the joint (hereinafter simply referred to as the outer diameter side) and the inner diameter side of the joint (hereinafter simply referred to as the inner diameter side). . The normal lines at each contact point intersect at the center of curvature O of the outer peripheral surface 11 a of the outer ring 11 . The angles formed by each normal line and the center line QQ in the width direction of the roller unit 4 are the contact angles αA and αB.

5 and 6 show a state in which a counterclockwise torque T is applied to the tripod member 3. FIG. As shown in FIG. 6, in a torque loaded state, the outer peripheral surface 11a of the outer ring 11 contacts the roller guide surface 6 on the load side (left side in the drawing), and the outer peripheral surface 11a of the outer ring 11 contacts on the non-load side (right side in the drawing). 11a and the roller guide surface 6 will be in a non-contact state. If the direction of torque load is reversed (clockwise), the right side of the drawing becomes the load side and the left side of the drawing becomes the non-load side. The non-contact relationship is the opposite of the above. In FIG. 6, P'-P' represents the axis of the leg axle 32 in a neutral state with no torque applied.

As described above, in the tripod joint in which the outer ring 11 and the roller guide surface 6 are in angular contact, the present invention relates to wear at the contact portion between the inner peripheral surface 12a of the inner ring 12 and the outer peripheral surface 32a of the leg shaft 32. According to their analysis, it became clear that the elastic deformation of the roller guide surface 6 that occurs during torque transmission affects the degree of wear.

Specifically, the following findings were clarified.
- As the contact ratio between the outer peripheral surface 11a of the outer ring 11 and the roller guide surface 6 increases, the surface pressure on the roller guide surface 6 increases. Since the elastic deformation amount of the roller guide surface 6 increases as the surface pressure increases, the elastic deformation amount of the roller guide surface 6 increases as the contact ratio increases. Here, the contact ratio means the ratio (RA/RD, RB/RD) of the curvature radii RA, RB of the roller guide surfaces 6a, 6b to the curvature radius RD of the outer peripheral surface 11a of the outer ring 11 .

・If the contact ratio is different between the outer diameter side and the inner diameter side of the roller guide surface 6 on the outer diameter side and the elastic deformation amount is made different, the roller unit 4 can be moved around the center of curvature O during torque transmission. By rotating, the axis of the roller unit 4 can be tilted with respect to the axis PP of the leg shaft 32 .

・As shown in FIG. 7, if the roller unit 4 rotates in the clockwise direction (arrow Y direction) with respect to the leg shaft 32 against the counterclockwise torque T acting on the tripod member 3, the inner ring 12 The clearance C between the inner peripheral surface 12a of the roller unit 4 and the outer peripheral surface 32a of the leg shaft 32 is larger on the inner diameter side than on the outer diameter side (Q'-Q' in FIG. 7 is the width direction of the roller unit 4 after tilting. center line). As the clearance C on the inner diameter side increases, the amount of lubricant (for example, grease) held in the clearance C on the inner diameter side increases.

・The centrifugal force generated by the rotational motion of the joint causes the lubricant enclosed inside the joint to move toward the outer diameter side. It becomes possible to supply the contact portion between 32 a and the inner peripheral surface 12 a of the inner ring 12 . Therefore, wear at the contact portion between the outer peripheral surface 32a of the leg shaft 32 and the inner peripheral surface 12a of the inner ring 12, particularly the wear of the outer peripheral surface 32a of the leg shaft 32, can be suppressed.

Based on the above verification results, in the tripod type constant velocity universal joint according to the present embodiment, the contact ratio (RB/RD) on the roller guide surface 6b on the inner diameter side is changed to the contact ratio on the roller guide surface 6a on the outer diameter side (RA/RD) (RA/RD<RB/RD). As a result, as shown in FIG. 5, during torque transmission, the amount of elastic deformation .delta.B of the roller guide surface 6b on the inner diameter side becomes greater than the amount of elastic deformation .delta.A of the roller guide surface 6a on the outer diameter side. As shown, the roller unit 4 swings clockwise (in the direction of the arrow Y) and tilts so that the area on the torque load side moves upward. Therefore, the clearance C between the inner peripheral surface 12a of the inner ring 12 and the outer peripheral surface 32a of the leg shaft 32 can be increased on the inner diameter side, and the amount of lubricant held in the clearance C can be increased. This lubricant is abundantly supplied to the contact portion between the outer peripheral surface 32a of the leg shaft 32 and the inner peripheral surface 12a of the inner ring 12 due to the centrifugal force. wear can be prevented.

The contact ratio (RA/RD) on the roller guide surface 6a on the outer diameter side is preferably in the range of 1.0<RA/RD<2.5, more preferably in the range of 1.0<RA/RD<2.2. . The contact ratio (RB/RD) on the roller guide surface 6b on the inner diameter side is preferably in the range of 1.5<RB/RD<3.0, more preferably in the range of 1.7<RA/RD<2.4. . If the roller guide surface 6a on the outer diameter side is set to 1 or less on each of the outer diameter side and the inner diameter side, two-point contact cannot be realized. When the contact ratio of the roller guide surface 6b on the inner diameter side is 1.5 or less, there is no substantial difference in the amount of elastic deformation with the roller guide surface 6a on the outer diameter side, and the effects of the present invention can be obtained. becomes difficult. When the curvature radii RA and RB of the roller guide surface 6a on the outer diameter side and the roller guide surface 6b on the inner diameter side are equal to or greater than the upper limit values, respectively, the contact angle becomes small, and the attitude of the roller unit 4 in the track groove 5 is reduced. is weakened.

Fig. 8 shows the results of actual measurement of the wear depth of the pedestal 32 when RA/RD>RB/RD (comparative product: left side) and when RA/RD<RB/RD (present invention product: right side). indicates From the results shown in FIG. 8, by setting RA/RD<RB/RD, the depth of wear of the outer peripheral surface 32a of the trunnion 32 is reduced to about half ( It became clear that it is possible to suppress up to β minutes of ).

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

For example, as shown in FIG. 9, the outer peripheral surface 32a of the leg shaft 32 can 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 can be formed into a cylindrical surface. Although not shown, the outer peripheral surface of the leg shaft 32 is formed into a convex curved surface (for example, a convex circular cross section), and the inner peripheral surface 12a of the inner ring 12 is formed into a concave spherical surface that fits with the outer peripheral surface of the leg shaft. can also

The tripod type constant velocity universal joint 1 described above is not limited to being applied 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 6a outer roller guide surface 6b inner roller guide surface 11 roller (outer ring)
12 Inner ring 12a Inner peripheral surface 13 Needle roller 32 Leg shaft 32a Outer peripheral surface RA Curvature radius of outer roller guide surface RB Curvature radius of inner roller guide surface RD Curvature radius of outer ring outer peripheral surface

Claims (4)

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 accommodated in each of the track grooves;
an inner ring fitted on the leg shaft and rotatably supporting 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 constitute a roller unit that can swing with respect to the leg shaft,
In a tripod type constant velocity universal joint in which the roller and the roller guide surface are in contact at two points on the joint outer diameter side and the joint inner diameter side,
Of the roller guide surfaces, RA/RD<RB where RA is the radius of curvature of the roller guide surface on the outer diameter side of the joint, RB is the radius of curvature of the roller guide surface on the inner diameter side of the joint, and RD is the radius of curvature of the outer peripheral surface of the roller. /RD, a tripod type constant velocity universal joint. The inner peripheral surface of the inner ring is formed into an arc-shaped convex surface 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. 2. The tripod type constant velocity universal joint according to claim 1, wherein a gap is formed between the tripod type constant velocity universal joint and the peripheral surface. 2. The tripod type constant velocity universal joint according to claim 1, wherein the inner peripheral surface of the inner ring is cylindrical and the outer peripheral surface of the leg shaft is spherical. 4. The tripod type constant velocity universal joint according to claim 1, wherein a plurality of rolling elements are arranged between said inner ring and said roller.

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