JP2013204686A - Universal joint and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a universal joint and a method of manufacturing the same, capable of improving sealability of a boot to shaft members.SOLUTION: A universal joint 1 includes two shaft members 11 and 17, a boot 20, and clampers 30 and 40. The clamper 40 has an annular projection strip part 41 projected inside in the radial direction on the center side in the axial direction more than positions provided with lip parts 233 and 234 on an inner peripheral surface of the clamper 40 opposed to an outer peripheral surface of an axial directional range R in the boot 20. When the boot 20 is fastened by the clamper 40, the projection strip part 41 seals by pressing the lip parts 233 and 234 to groove side surfaces 171b and 171c of an annular groove 171 by pressing the center side in the axial direction more than the lip parts 233 and 234 on the outer peripheral surface of the boot 20.

Description

  The present invention relates to a universal joint and a method of manufacturing the same, and more particularly, to a clamper used for fastening a boot covering two members constituting the universal joint to a mating member.

  As a universal joint, for example, Patent Document 1 discloses a constant velocity joint that is applied to a drive shaft of a vehicle. In such a universal joint, the joint portions of the two rotating shaft members are covered with boots to prevent dust from entering the joint portions. In addition, the universal joint boot is mounted on the outer peripheral surface of the shaft member by a clamper, but is required to have a sealing function to prevent the grease sealed inside the boot from leaking to the outside. Therefore, for example, Patent Document 2 discloses a structure in which a convex portion is formed on the inner peripheral surface of the clamper so as to face the engaging groove of the shaft member. According to such a configuration, since the boot can be reliably fixed to the shaft member, it is said that high sealing performance can be maintained with respect to the boot mounting portion of the shaft member.

JP 2009-85282 A JP 2010-112474 A

  By the way, as a boot of a universal joint, there are rubber and resin. Rubber boots and resin boots have high hardness and rigidity due to thermal degradation. If the hardness and rigidity of the boot are increased, the surface pressure against the shaft member is lowered, and depending on the boot position, a gap may be formed between the shaft member and the sealing performance may be lowered. In addition, since the boot is pressed radially inward by the clamper, if a compressive force is continuously applied over a long period of time, plastic flow may occur, which may also reduce the sealing performance.

  This invention is made | formed in view of such a situation, and it aims at providing the universal joint which can improve the sealing performance of the boot with respect to a shaft member, and its manufacturing method.

  (Claim 1) A universal joint according to the present invention includes two shaft members that are connected to each other so that their relative angles are variable or movable in the direction of the rotation axis, and have an annular groove on the outer peripheral surface. A boot that covers the gap, and a clamper that tightens the outer peripheral surface of the boot so as to be sealed between the annular groove and the boot, and the boot has an outer periphery of the annular groove on the inner peripheral surface. An annular lip portion projecting radially inward is provided at an end of the axial range located at a position of the clamper, and the clamper includes an inner peripheral surface of the clamper that is opposed to the outer peripheral surface of the axial range of the boot. A ring-shaped ridge projecting radially inwardly on the axial center side than the position where the lip is provided, and when the boot is tightened by the clamper, the ridge is formed on the outer periphery of the boot. Of the surface By pressing the axial center side than the part to seal against the lip in the groove side surface of the annular groove.

  (Claim 2) In addition, the boot has a plurality of the lip portions that are accommodated in the annular groove, and are provided so that the protrusions of the clamper are positioned between the boots, When tightened by a clamper, the plurality of lip portions may be sealed between the groove side surfaces on both axial sides of the annular groove.

  (Claim 3) Further, the clamper may be formed in a V shape or a convex curve shape with a cross-sectional shape having the protrusion portion as a minimum diameter portion.

  (Claim 4) A method for manufacturing a universal joint according to the present invention includes two shaft members that are connected to each other so that their relative angles are variable or movable in the direction of the rotation axis, and that have an annular groove on the outer peripheral surface, and the two A universal joint manufacturing method comprising: a boot that covers between shaft members; and a clamper that tightens an outer peripheral surface of the boot so as to be sealed between the annular groove and the boot. A plurality of annular lip portions projecting radially inward are provided at both ends of the axial range located on the outer side of the annular groove on the inner peripheral surface, and the clamper is provided in the axial range of the boot. Out of the inner peripheral surface of the clamper facing the outer peripheral surface, the clamper has an annular ridge that protrudes radially inward on the center side in the axial direction from the position where the lip portion is provided. Tighten by Te, wherein the protrusions are by pressing between a plurality of the lip portion of the outer peripheral surface of the boot to seal against a plurality of said lip into the groove side of both axial sides of said annular groove.

  (Claim 1) According to the present invention, when the boot is tightened by the clamper, the lip portion is pressed against the groove side surface of the annular groove. Here, conventionally, the boot is pressed radially inward against the annular groove by a clamper, and sealed with the groove bottom of the annular groove. For this reason, it has been found that, due to changes in the hardness of the boot and the like, gaps may be formed particularly between the groove side surfaces, which reduces the sealing performance. Therefore, in the present invention, with the above-described configuration, the lip portion is positively pressed over the entire circumference of the annular groove to enable sealing between the groove side.

  More specifically, when the clamper is reduced in diameter and the boot is tightened, the portion of the boot that contacts the ridge portion of the clamper is compressed toward the groove bottom of the annular groove, and the region between the portion and the lip portion is compressed. The side portion moves toward the groove side surface of the annular groove. By deforming the boot in this manner, the lip portion is reliably pressed against the groove side surface of the annular groove. Thereby, in addition to a groove bottom face, it can seal between groove side surfaces, and can maintain high sealing performance with respect to a shaft member, even if the hardness of a boot etc. change.

  (Claim 2) According to the present invention, the boot has a plurality of lip portions provided so that the protrusions of the clamper are positioned therebetween, and when the boot is tightened by the clamper, both sides of the annular groove in the axial direction Each lip portion seals with the groove side surface. As a result, the lip portions are pressed against the groove side surfaces of the annular groove by axial pressing forces in opposite directions, so that the axial pressing force can be set large without using another axial movement restricting means. Therefore, the boot enables a high seal between the groove side surfaces on both sides in addition to the groove bottom of the annular groove in the shaft member. For this reason, even if the hardness of the boot or the like changes, it is possible to suppress the formation of a gap between the annular groove and the groove side surface. As a result, high sealing performance can be maintained. Furthermore, the axial movement of the site | part clamped by the clamper in boots can be controlled by contacting the groove side surface of both axial directions.

  (Claim 3) According to the present invention, the cross-sectional shape of the clamper is formed in a V shape or a convex curve shape. Therefore, when the boot is tightened by the clamper, each part of the boot gradually moves from the part in contact with the ridge part toward the end part, so that the boot is suitably deformed and the lip part is formed on the groove side surface of the annular groove. Can be pressed more reliably.

(Claim 4) According to the present invention, when the clamper is reduced in diameter and the boot is tightened, the portion of the boot that contacts the ridge portion of the clamper is compressed toward the groove bottom of the annular groove. The side portion between the lip portion moves toward the groove side surface of the annular groove. By deforming the boot in this way, each lip portion is pressed against the groove side surface of the annular groove by the axial pressing forces in the opposite directions, so that each lip portion is securely attached to the groove side surface on both sides in the axial direction of the annular groove. Pressed. Thereby, in addition to a groove bottom face, it can seal between groove side surfaces, and can maintain high sealing performance with respect to a shaft member, even if the hardness of a boot etc. change. Further, the axial pressing force can be set large without using another axial movement restricting means for the boot. Thereby, since each lip part contacts the groove | channel side surface of an axial direction both sides reliably, the axial direction movement of the site | part clamped by the clamper in boots can be controlled.
Further, other characteristic portions in the universal joint can be similarly applied to the manufacturing method of the present invention. In this case, the same effect is obtained.

It is an axial sectional view of the constant velocity joint in the embodiment. FIG. 2 is an enlarged axial sectional view of a clamp part and a clamper of a boot in FIG. 1. It is an expanded axial sectional view which shows the state before clamping the clamp part of boots with a clamper. It is a figure which shows the state in which the boot in FIG. 3 is sealed between the annular grooves of the shaft by the clamper. It is an expanded axial direction sectional view of a clamp part of a boot and a clamper in a modification of an embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments in which a universal joint of the present invention and a manufacturing method thereof are embodied will be described with reference to the drawings. In addition, in embodiment, the constant velocity joint applied to the drive shaft of a vehicle as a universal joint is illustrated.

<Embodiment>
(Overall configuration of constant velocity joint 1)
The overall configuration of the constant velocity joint 1 of the present embodiment will be described with reference to FIG. The constant velocity joint 1 is a sliding tripod type constant velocity joint, and is used as a drive shaft for connecting a differential gear of a vehicle and an axle. As shown in FIG. 1, the constant velocity joint 1 includes a joint portion 10, a boot 20, and a large-diameter clamper 30 and a small-diameter clamper 40 that are respectively attached to both ends of the boot 20.

  The joint portion 10 connects the outer ring 11 and the shaft 17 as two shaft members so that their relative angles are variable and movable in the rotation axis direction. Specifically, the joint portion 10 includes an outer ring 11, a tripod 12, a roller 13, a plurality of axial rolling elements 14, a retainer 15, a snap ring 16, and a shaft 17. The outer ring 11 is formed in a bottomed cylindrical shape, for example, and the outer bottom surface of the outer ring 11 is connected to the differential gear. Further, three track grooves 111 extending in the direction of the outer ring rotation axis are formed on the inner peripheral surface of the outer ring 11 at equal intervals in the circumferential direction.

  The tripod 12 includes a boss portion 121 and three tripod shaft portions 122 that are provided on the outer side in the radial direction of the boss portion 121 and are provided at equal intervals in the circumferential direction. The tripod 12 is disposed inside the outer ring 11. The roller 13 is formed in an annular shape and is pivotally supported on the outer peripheral side of the tripod shaft portion 122 via a plurality of shaft-like rolling elements 14. That is, the roller 13 is arranged so as to be rotatable with respect to each tripod shaft portion 122 and slidable in the axial direction. Further, the roller 13 is fitted into the raceway groove 111 and is engaged with the raceway groove 111 so as to be able to roll.

  The retainer 15 is arranged on the outer peripheral side of the tripod shaft 122 and adjacent to the axial rolling element 14 in the axial direction. The retainer 15 regulates the axial movement of the axial rolling element 14 with respect to the tripod shaft 122 and has a role of preventing the axial rolling element 14 from coming off. The retainer 15 is prevented from falling off the tripod shaft 122 by the snap ring 16 that is locked in the ring groove of the tripod shaft 122. One end of the shaft 17 is fitted to the boss 121 of the tripod 12.

  Further, on the opening side (the right side in FIG. 1) of the outer peripheral surface of the outer ring 11, an annular groove 112 is formed that is pressed against the large diameter side clamp portion 22 of the boot 20 and sealed with the boot 20. ing. Further, on the outer peripheral surface of the shaft 17, an annular groove 171 is formed which is pressed against the clamp 20 on the small diameter side of the boot 20 and sealed with the boot 20.

  The boot 20 is formed in a cylindrical shape as a whole, and covers between the two shaft members, that is, between the opening side of the outer ring 11 and the outer peripheral surface of the shaft 17. The boot 20 is made of resin or rubber. The boot 20 includes a bellows portion 21, a large diameter clamp portion 22, and a small diameter clamp portion 23. The bellows portion 21 can be expanded and contracted in the center line direction of the boot 20 and is deformed so as to follow a change in joint angle (the relative angle between the outer ring 11 and the shaft 17).

  The large diameter clamp part 22 seals between the outer peripheral surface of the outer ring 11 which is a counterpart member by pressing the outer peripheral surface radially inward by the large diameter clamper 30. Further, the small diameter clamp portion 23 seals between the outer peripheral surface of the shaft 17 which is the counterpart member by pressing the outer peripheral surface radially inward by the small diameter clamper 40.

  As the large-diameter clamper 30 and the small-diameter clamper 40, for example, an Ω-type boot band, a folded (one-touch) boot band, or the like is applied. The large-diameter clamper 30 is attached to the outer peripheral side of the large-diameter clamp portion 22 of the boot 20 and tightens the large-diameter clamp portion 22 by being reduced in diameter by caulking or the like. Accordingly, the large-diameter clamp portion 22 is pressed against the outer peripheral surface of the outer ring 11. In this way, sealing performance is exhibited between the large-diameter clamp portion 22 and the outer ring 11.

  The small-diameter clamper 40 is mounted on the outer peripheral side of the small-diameter clamp portion 23 of the boot 20, and, like the large-diameter clamper 30, is reduced in diameter by caulking or the like, thereby tightening the small-diameter clamp portion 23. Accordingly, the small diameter clamp portion 23 is pressed against the outer peripheral surface of the shaft 17. In this way, the sealing performance is exhibited between the small diameter clamp portion 23 and the shaft 17.

(Detailed structure of seal structure)
As described above, the small-diameter clamp portion 23 of the boot 20 exerts a function of being pressed against the outer peripheral surface of the shaft 17 by the small-diameter clamper 40 and sealing with the outer peripheral surface. That is, in the constant velocity joint 1, the annular groove 171 of the shaft 17, the small-diameter clamp portion 23 of the boot 20, and the small-diameter clamper 40 constitute a small-diameter side seal structure. Similarly, a large-diameter side seal structure is configured by the annular groove 112 of the outer ring 11, the large-diameter clamp portion 22 of the boot 20, and the large-diameter clamper 30. Here, the detailed configuration of the seal structure on the small diameter side will be described with reference to FIGS.

  With regard to this small-diameter side seal structure, first, the shapes of the small-diameter clamp portion 23 and the small-diameter clamper 40 in a state where the boot 20 is not disposed on the shaft 17, that is, a state where the small-diameter clamper 40 is not pressed radially inward will be described. . As shown in FIG. 2, a mounting groove 231 for mounting the small-diameter clamper 40 is formed on the outer peripheral surface of the small-diameter clamp portion 23 over the entire circumference. Thereby, the small diameter clamper 40 is positioned in the axial direction by the shoulder portions on both sides in the axial direction constituting the mounting groove 231 and is prevented from falling off the boot 20. Here, the “axial direction” refers to the extending direction of the central axis of the small-diameter clamp portion 23 having a cylindrical shape. Further, as shown in FIG. 3, the mounting groove 231 is disposed so as to be positioned outside the annular groove 171 of the shaft 17 when the boot 20 is mounted on the shaft 17 by the small diameter clamper 40.

  Further, two lip portions 233 and 234 projecting radially inward are formed in an annular shape over the entire circumference in the circumferential direction on the inner peripheral surface of the small diameter clamp portion 23. These lip portions 233 and 234 have a trapezoidal cross-sectional shape in the axial direction, and are provided radially inward of the mounting groove 231. The lip portions 233 and 234 are provided at both ends of the axial range R located outside the annular groove 171 of the shaft 17 on the inner peripheral surface of the small diameter clamp portion 23. The axial range R is a range in the inner peripheral surface of the small-diameter clamp portion 23 that is opposed to the annular groove 171 in the radial direction and can contact the annular groove 171 when the boot 20 is attached to the shaft 17.

  The small-diameter clamper 40 has an annular ridge 41 projecting radially inward on the inner peripheral surface. In the present embodiment, as shown in FIG. It is formed in a V shape. More specifically, the protruding portion 41 is located at a position where the lip portions 233 and 234 are provided in the small-diameter clamp portion 23 on the inner peripheral surface of the small-diameter clamper 40 facing the outer peripheral surface of the axial range R of the boot 20. Is also located on the axially central side. That is, when the small-diameter clamper 40 is mounted on the boot 20, the small-diameter clamper 40 is positioned in the mounting groove 231 so that the protrusion 41 is positioned on the axial center side with respect to the lip portions 233 and 234. The two lip portions 233 and 234 are accommodated in the annular groove 171 and provided so that the protruding portion 41 of the small diameter clamper 40 is located therebetween.

  Further, as shown in FIG. 3, the protruding portion 41 of the small diameter clamper 40 is the first in the boot 20 among the inner peripheral surfaces of the small diameter clamper 40 to be reduced in diameter when the small diameter clamper 40 tightens the outer peripheral surface of the boot 20. It is the site | part formed so that it might contact the outer peripheral surface (more specifically, the groove bottom face of the mounting groove 231). That is, in the small-diameter side seal structure, when the boot 20 is tightened by the small-diameter clamper 40, the protruding portion 41 presses the center side in the axial direction from the lip portions 233 and 234 on the outer peripheral surface of the boot 20. Thus, the lip portions 233 and 234 are pressed against the groove side surfaces 171b and 171c of the annular groove 171 in the shaft 17. Further, in the present embodiment, the ridge portion 41 is configured to correspond to both lip portions 233 and 234 on both sides, but two ridge portions corresponding to each of the two lip portions 233 and 234 are provided. You may do it.

(Installation process of boot 20 to shaft member)
In each member constituting the seal structure described above, a process (manufacturing method) in which the small-diameter clamp portion 23 is disposed on the outer peripheral surface of the shaft 17 that is the shaft member and the boot 20 is mounted by the small-diameter clamper 40 is shown in FIGS. This will be described with reference to FIG. First, as shown in FIG. 3, the small-diameter clamp portion 23 of the boot 20 is arranged so that the lip portions 233 and 234 are adjacent to the groove side surfaces 171 b and 171 c of the annular groove 171 with respect to the annular groove 171 of the shaft 17. Is done. When the diameter of the small-diameter clamper 40 is reduced in such a state, as shown in FIG. 3, the protrusion 41 of the small-diameter clamper 40 and the groove bottom of the mounting groove 231 in the small-diameter clamp part 23 first come into contact with each other. .

  When the diameter of the small-diameter clamper 40 is further reduced and the boot 20 is tightened, a portion of the small-diameter clamp portion 23 that contacts the protrusion 41 is pressed toward the groove bottom surface 171a side of the annular groove 171 and compressed. . Further, the side portion between this portion and each of the lip portions 233 and 234 moves toward the groove side surfaces 171b and 171c of the annular groove 171. Further, since the small diameter clamper 40 is formed in a V-shaped cross section, the small diameter clamp portion 23 gradually moves from the center side toward the end portion side as the diameter of the small diameter clamper 40 is reduced. It will be transformed into.

  Accordingly, the lip portions 233 and 234 are pressed inward in the radial direction, and pressed against the groove side surfaces 171b and 171c of the annular groove 171 over the entire circumference. When the diameter of the small-diameter clamper 40 is reduced to a predetermined inner diameter, the boot 20 is sealed with the annular groove 171 of the shaft 17 as shown in FIG. At this time, the small-diameter clamp portion 23 is deformed as described above in the tightening process, and the lip portions 233 and 234 are pressed against the groove side surfaces 171b and 171c of the annular groove 171 as indicated by arrows in FIG. In the present embodiment, a part of the lip portions 233 and 234 is in contact with the groove bottom surface 171a of the annular groove 171 and is sealed between the groove bottom surface 171a.

(Effects of the configuration of the embodiment)
According to the constant velocity joint 1 described above, the lip portions 233 and 234 are pressed against the groove side surfaces 171b and 171c of the annular groove 171, and sealing is performed between the groove side surfaces 171b and 171c. That is, in the constant velocity joint 1 of the present embodiment, when the small diameter clamper 40 having the ridge 41 tightens the small diameter clamp portion 23 in the axially inward direction, the small diameter clamp portion 23 is elastically deformed, and the annular groove 171 is formed. In addition to the groove bottom surface 171a, sealing is performed between the groove side surfaces 171b and 171c. Thereby, even if the hardness of the boot 20 etc. change, a high sealing performance with respect to the shaft 17 can be maintained.

  Further, the boot 20 of the constant velocity joint 1 has a plurality of lip portions 233 and 234. As a result, the boot 20 is pressed against the groove side surfaces 171b and 171c of the annular groove 171 by the axial pressing forces in opposite directions, so that the lip portions 233 and 234 are pressed without using another axial movement restricting means. The direction pressing force can be set large. Therefore, a high seal is possible between the groove side surfaces 171b and 171c on both sides of the annular groove 171 in the shaft 17.

  Therefore, even if the hardness of the boot 20 changes, it can suppress that a clearance gap produces between the groove side surfaces 171b and 171c of the annular groove 171. As a result, high sealing performance can be maintained. Furthermore, the axial movement of the part fastened to the small diameter clamper 40 in the boot 20 can be restricted by contacting the groove side surfaces 171b and 171c on both axial sides.

  The small-diameter clamper 40 is formed in a V shape having the ridge 31 as the minimum diameter, and is formed so that the ridge 31 first contacts the outer peripheral surface of the boot 20 when the diameter is reduced. Yes. As a result, when the boot 20 is tightened by the small diameter clamper 40, the side portion between the portion that contacts the protrusion 41 and the lip portions 233 and 234 moves toward the groove side surfaces 171 b and 171 c of the annular groove 171. To do. Further, when the small-diameter clamper 40 is reduced in diameter, the small-diameter clamp part 23 is deformed so that each part gradually moves from the center side toward the end part side. As the boot 20 is deformed in this manner, the lip portions 233 and 234 are reliably pressed against the groove side surfaces 171b and 171c of the annular groove 171, so that the sealing performance of the boot 20 with respect to the shaft member can be improved.

<Modification of Embodiment>
In the present embodiment, a sliding tripod type constant velocity joint has been described as an example of a universal joint. Here, the characterizing portion of the present invention is a configuration related to a boot and a mating member that seals between the boot. Therefore, the present invention can also be applied to other fixed-type constant velocity joints or non-constant velocity joints. In the boot 20, the small-diameter clamp portion 23 has been described, but the present invention can also be applied to the large-diameter clamp portion 22.

  In addition, the small-diameter clamper 40 has a V-shape with the protruding portion 41 as the minimum diameter portion in the axial cross-sectional shape. On the other hand, the small-diameter clamper 40 may be formed such that the cross-sectional shape in the axial direction is a convex curve with the protruding portion 41 as the minimum diameter portion. Further, the lip portions 233 and 234 of the boot 20 have a trapezoidal cross section in the axial direction. On the other hand, the cross-sectional shape of each part in the boot 20 and the small-diameter clamper 40 can be appropriately set corresponding to the shape of the annular groove of the mating member. For example, as shown in FIG. 5, the small-diameter clamper 140 may include a cylindrical portion 142 that extends in the axial direction and a ridge portion 141 that protrudes radially inward at the axial central portion of the cylindrical portion 142. Good. Even in such a configuration, the same effects as in the embodiment can be obtained.

  Further, in the small diameter clamper 40 of the present embodiment, the one protruding portion 41 corresponds to the two lip portions 233 and 234 of the small diameter clamp portion 23 in the boot 20 in common. On the other hand, when the small-diameter clamp part 23 has a plurality of lip parts as in the present embodiment, a configuration may be provided in which protrusions corresponding to the respective lip parts are provided. As a result, for example, when the clamp portion of the boot has a certain length in the axial direction, it is possible to suitably seal by providing protrusions with respect to the plurality of lip portions.

1: constant velocity joint (universal joint), 10 joint part, 11: outer ring (shaft member), 111: raceway groove, 12: tripod, 121: boss part, 122: tripod shaft part, 13: roller, 14: needle, 15: retainer, 16: snap ring, 17: shaft (shaft member), 171: annular groove, 171a, 171b: groove side surface, 20: boot, 21: bellows part, 22, 23: clamp part, 231: mounting groove, 233, 234: Lip part, 30: Large diameter clamper, 40, 140: Small diameter clamper, 41, 141: Projection part, 142: Cylindrical part

Claims (4)

Two shaft members that are connected to each other so that their relative angles are variable or movable in the direction of the rotation axis, and have an annular groove on the outer peripheral surface
A boot covering between the two shaft members;
A clamper that tightens the outer peripheral surface of the boot so as to be sealed between the annular groove and the boot,
The boot is provided with an annular lip projecting radially inwardly at an end of an axial range located outside the annular groove on the inner peripheral surface,
The clamper has an annular shape that protrudes radially inwardly on the axial center side of the inner peripheral surface of the clamper that faces the outer peripheral surface of the axial range of the boot from the position where the lip portion is provided. Has a ridge,
When the boot is tightened by the clamper, the projecting portion presses the center side in the axial direction from the lip portion of the outer peripheral surface of the boot, thereby pressing the lip portion against the groove side surface of the annular groove for sealing. Universal joint. The boot has a plurality of the lip portions that are accommodated in the annular groove and are provided so that the protrusions of the clamper are positioned therebetween,
The universal joint according to claim 1, wherein when the boot is tightened by the clamper, the plurality of lip portions seals between the groove side surfaces on both axial sides of the annular groove.   The universal joint according to claim 1, wherein the clamper is formed in a V shape or a convex curve shape with a cross-sectional shape having the protrusion portion as a minimum diameter portion. Two shaft members that are connected to each other so that their relative angles are variable or movable in the direction of the rotation axis, and have an annular groove on the outer peripheral surface
A boot covering between the two shaft members;
A clamper for tightening an outer peripheral surface of the boot so as to be sealed between the annular groove and the boot,
The boot is provided with a plurality of annular lip portions projecting radially inward at both ends of the axial range located outside the annular groove on the inner peripheral surface,
The clamper has an annular shape that protrudes radially inwardly on the axial center side of the inner peripheral surface of the clamper that faces the outer peripheral surface of the axial range of the boot from the position where the lip portion is provided. Has a ridge,
The boots are tightened by the clamper, and the ridges press between the plurality of lip portions of the outer peripheral surface of the boot, whereby the plurality of lip portions are groove side surfaces on both axial sides of the annular groove. Of universal joints that are pressed against and sealed.

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