JP2004360817A - Boot for constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the engagement of an edge part of an outer casing of a constant velocity universal joint with an inner face of a boot for the constant velocity universal joint. <P>SOLUTION: This boot for the constant velocity universal joint is composed of a large end part to which the outer casing of the constant velocity universal joint is inserted, a small end part to which a shaft part connected with the constant velocity universal joint is inserted, and bellows formed between the large end part and the small end part, the large end part has a face part faced to an end face of a tip part of the outer casing of the constant velocity universal joint, and a part faced to an end face inner peripheral part of the tip part of the outer casing, of the face part is recessed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a boot for protecting a constant velocity universal joint provided on a drive shaft (power transmission shaft) for transmitting power from a differential (differential) gear of an automobile to an axle hub, and more particularly, to a boot for protecting a constant velocity universal joint. The present invention relates to prevention of damage to a boot due to a sharp edge of an end surface of an outer casing of a constant velocity joint.
[0002]
[Prior art]
For example, a drive shaft for an automobile uses constant velocity joints at both ends. A grease for lubricating the constant velocity joint is sealed therein, and a flexible boot covering the bent portion of the constant velocity joint is mounted to prevent foreign substances such as dust and water from entering from outside. Such boots usually have a large end portion and a small end portion respectively connected to the outer peripheral surface of the outer casing of the constant velocity joint on the differential side or the hub side and the outer peripheral surface of the drive shaft shaft portion by means of fastening means such as a band. Fixed by fastening. (For example, see Patent Document 1)
[0003]
In addition, in order to prevent the large end of the constant velocity joint boot and the outer casing of the constant velocity joint from being displaced in the axial direction, the leading end of the outer casing of the constant velocity joint is provided on the inner peripheral side of the large end of the boot. It is known to form a surface facing the end face.
[0004]
[Patent Document 1]
JP-A-2002-39208 (page 1, FIG. 1 and the like)
[0005]
[Problems to be solved by the invention]
However, in the boot for a constant velocity joint as described above, the inner peripheral edge of the tip of the outer casing (casing) of the cylindrical constant velocity joint and the inner surface of the boot are different from each other. When the bending of the drive shaft caused by the suspension stroke or the steering operation is performed, the inner peripheral surface of the boot in contact with the end surface of the distal end of the outer casing of the constant velocity joint becomes the tip of the outer casing of the constant velocity joint. The so-called "biting" may be caused by being pressed against the part. If such biting can occur, care must be taken to prevent the boot from being damaged by sharp edges or burrs formed by machining the tip of the outer casing of the constant velocity joint.
In view of the above-mentioned problem, an object of the present invention is to prevent the inner edge of the constant velocity joint boot from being caught by the edge of the outer casing of the constant velocity joint.
[0006]
[Means to solve the problem]
According to the present invention, a large end into which an outer casing of a constant velocity joint is inserted, a small end into which a shaft connected to the constant velocity joint is inserted, and a large end and a small end are formed between the large end and the small end. A constant velocity joint boot having a bellows and a large end portion having a surface portion facing an end surface of a distal end portion of an outer casing of the constant velocity joint, and this surface portion is The above-mentioned object is achieved by a constant velocity joint boot characterized in that a portion facing the inner peripheral portion of the end face of the distal end portion of the outer casing is recessed.
[0007]
According to the present invention, a gap is formed between the inner surface of the constant velocity joint boot and the inner peripheral edge of the outer casing of the constant velocity joint where sharp edges and burrs are easily formed. The shape of the surface portion is appropriately set so that the gap does not become zero even when the boot is bent at a predetermined maximum bending angle, so that the inner surface of the boot and the sharp edge are in contact regardless of the bending of the boot. Since it is possible to prevent the occurrence of biting, it is possible to prevent the edge of the outer casing of the constant velocity joint from biting into the inner surface of the constant velocity joint boot.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a constant velocity joint boot according to the present invention will be described. FIG. 1 is an elevation view showing the appearance of the constant velocity joint boot of the present embodiment. As shown in FIG. 1, the boot 1 is formed in a cylindrical shape as a whole, and is fixed to a large end portion 3 fixed to a constant velocity joint side and to a shaft side of a drive shaft connected to the constant velocity joint. And a small end 5. Further, between the large end 3 and the small end 5, a bellows 7 having a bellows shape, which is flexible and bendable, is formed. In the case of the present embodiment, the boot 1 is formed from an elastic resin such as a thermoplastic polyester elastomer.
[0009]
The bellows 7 is configured such that convex portions 7a and concave portions 7b extending in the circumferential direction are repeatedly arranged in the cylinder axis direction of the boot 1, that is, in the vertical direction in FIG. That is, in the convex portion 7a, the cross section of the bellows 7 is convex toward the outer peripheral side, and in the concave portion 7b, the cross section of the bellows 7 is convex in the inner peripheral side. In the case of the present embodiment, for example, five convex portions 7a are provided, and a concave portion 7b corresponding to the large end 3 side of each 7a is provided. The diameter of each of the convex portions 7a and the concave portions 7b is set to be larger as going from the small end portion 5 side to the large end portion 3 side. As a result, the bellows 7 is formed in a substantially conical shape as a whole. I have.
[0010]
The outer peripheral surface of the side of the large end portion 3 is provided with a surface portion 9 having a substantially constant outer diameter in the axial direction. A band (not shown) for fastening the boot 1 to an outer peripheral surface of an outer casing of a tripod joint (not shown), which is a constant velocity joint, is attached to the surface portion 9. Note that the tripod joint is a type of constant velocity joint, in which rollers arranged in a trifurcated lock are provided around the circumference of the shaft, and a groove portion on which these rollers slide is provided on the inner peripheral side of the casing or the outer casing. It refers to what is formed. Further, a step portion 11 for preventing the band from shifting in the axial direction is formed at the end of the surface portion 9 on the small end portion 5 side of the boot 1 in the cylinder axis direction.
[0011]
FIG. 2 is an enlarged sectional view showing a state where an outer casing of the constant velocity joint is inserted into the large end 3 of the constant velocity joint boot 1 of the present embodiment. The distal end portion 15 of the outer casing 13 of the constant velocity joint on the side to be inserted into the large end portion 3 is formed in a cylindrical shape, and concave portions characteristic of a tripod joint are formed at three places on the periphery thereof. The inner peripheral surface 17 of the distal end portion 15 is formed to have a constant inner diameter in the cylinder axis direction, except for the inner surface of the above-described concave portion. On the other hand, the tip portion 15 has an annular end face 19 facing the small end portion 5 side of the boot 1 in the cylinder axis direction. A tapered portion 21 is formed from the outer peripheral edge of the end surface 19 to the side surface of the distal end portion 15. The boundary between the end face 19 and the tapered portion 21 is rounded. Further behind the tapered portion 21, that is, on the left side as viewed in FIG. 2, a parallel portion 23 having a constant outer diameter, a tapered portion 25 having an outer diameter gradually reduced toward the rear side, and a rear end of the tapered portion 25 Parallel portions 27 having substantially the same outer diameter as the portion are formed in order from the front end side.
[0012]
On the other hand, as shown in FIG. 2, the inner surface of the large end 3 of the boot 1 is also formed with a surface portion having a shape conforming to the end surface 19, the tapered portion 21, the parallel portion 23, the taper portion 25, and the parallel portion 27. However, the annular surface portion 31 on the boot 1 side facing the end surface 19 of the outer casing 13 of the constant velocity joint has an inner peripheral edge or a minimum diameter portion 33 whose diameter is smaller than the minimum diameter of the end surface 19 of the outer casing 13. It is formed large. In the inner surface of the boot 1 on the inner peripheral side of the annular surface portion 31, an annular concave portion 34 formed to be recessed toward the small end portion 5 in the cylinder axis direction of the boot 1 relative to the annular surface portion 31. Is formed. As shown in FIG. 2, the concave surface portion 34 is formed in a concave shape having an arc shape as viewed from the stepped surface. A boundary portion where the concave surface portion 34 contacts the annular surface portion 31 is formed in an edge shape having a corner. For example, at a boundary portion between the annular surface portion 31 and the concave surface portion 34, these two surfaces are formed at an angle of about 45 degrees, for example. ing. On the other hand, the innermost peripheral portion of the concave portion 34 is formed in a tapered shape having a slight inclination with respect to a plane orthogonal to the cylinder axis of the boot 1. By forming such a concave portion 34, a relief portion 35 which is an annular gap is formed between the end surface 19 of the outer casing 13 of the constant velocity joint and the concave portion 34.
[0013]
As shown in FIG. 2, a region of the inner surface of the boot 1 on the inner peripheral side of the inner peripheral edge of the concave surface portion 34 is formed as a convex surface having an arcuate cross-sectional shape, and a step from the inner peripheral edge 37 of the convex surface portion. It is in contact with the inner peripheral surface of the bellows 7 via a step portion 39 provided with an enlarged diameter.
[0014]
FIG. 3 is a cross-sectional view showing a state in which the bellows 7 is bent with the outer casing 13 of the constant velocity joint inserted into the large end 3 of the constant velocity joint boot 1 of the present embodiment. This figure shows a state in which the axial direction of the large end 3 is fixed and the axial direction of the small end 5 is shifted clockwise toward FIG. The angle between the axial direction of the small end portion 5 and the axial direction of the large end portion 3 is, for example, the maximum bending angle of the constant velocity joint to which the constant velocity joint boot of the present embodiment is attached. FIG. 4 is an enlarged sectional view of a portion IV in FIG. In FIG. 4, a contour line before bending the boot 1 is illustrated by a broken line for reference. As shown in FIG. 4, even in this state, the distance between the concave surface 34 which is the inner surface of the large end 3 of the boot 1 and the end surface 19 of the outer casing 13 of the constant velocity joint is smaller than that shown in FIG. However, they face each other at intervals without contact. In addition, as shown in FIG. 4, the diameter r1 at the largest diameter portion of the concave surface portion 34 is set to be larger than the inner diameter r2 of the end face 19.
[0015]
As described above, according to the present embodiment, the space between the inner surface of the constant velocity joint boot 1 and the inner peripheral edge portion 36 of the end surface 19 of the outer casing 13 of the constant velocity joint in which sharp edges and burrs are easily formed. An escape portion 35 is formed. The concave portion 34 is formed so that the space between the escape portions 35 does not become 0 even when the boot 1 is bent at a predetermined maximum bending angle. The inner surface 34 and the like and the inner peripheral edge 36 of the end surface 19 can be prevented from contacting each other, and the edge of the outer casing 13 of the constant velocity joint is prevented from being caught in the inner surface of the constant velocity joint boot 1. Can be.
[0016]
Note that the present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the invention. For example, the shape of the outer casing of the constant velocity joint or the shape of the large end may be changed. Also, the shape of the bellows and the small end can be appropriately changed. Further, in the present embodiment, the boot is formed of a resin. However, for example, the grommet portion on the inner peripheral side of the large end may be formed separately from a resin or rubber having a lower hardness than the resin of the boot body. . Further, the entire boot may be formed integrally with only this low-altitude resin or rubber.
[0017]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the bite of the edge part of the outer casing of a constant velocity joint can be prevented from entering into the inner surface of the constant velocity joint boot.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of one embodiment of a constant velocity joint boot to which the present invention is applied.
FIG. 2 is an enlarged cross-sectional view when an outer casing of the constant velocity joint is inserted into a large end of the constant velocity joint boot of FIG.
FIG. 3 is a view showing a state in which the outer casing of the constant velocity joint is inserted into a large end portion of the constant velocity joint boot of FIG. 1 and the boot is bent.
FIG. 4 is an enlarged sectional view of a portion IV in FIG. 3;
[Explanation of symbols]
Reference Signs List 1 boot for constant velocity joint 3 large end 5 small end 7 bellows 7a convex part 7b concave part 13 outer casing 19 of constant velocity joint end surface 31 annular surface part 34 concave surface part 35 relief part (gap)

Claims (1)

A large end into which the outer casing of the constant velocity joint is inserted, a small end into which the shaft connected to the constant velocity joint is inserted, and a bellows formed between the large end and the small end. A constant velocity joint boot comprising: a large end portion having a surface portion facing an end surface of a distal end portion of an outer case of the constant velocity joint, and the surface portion of the outer case is A boot for a constant velocity joint, characterized in that a portion facing the inner peripheral portion of the end face of the distal end portion is formed to be concave.

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