JP2005344934A - Joint boots made of resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide joint boots made of resin which suppresses the occurrence of a crack to the recessed part for fixing of a small cylinder part and is excellent in durability. <P>SOLUTION: In joint boots 10 made of resin comprising: a small cylinder part 12; a large cylinder part 14 situated separately from and coaxially with the small cylinder part 12; and a bellows part 16 integrally coupling together the small cylinder part 12 and the large cylinder part 14, a recessed part 20 for fixing to receive a tightening clamp 4 is formed in the outer peripheral surface of the small cylinder part 12, a notch part 24 is formed by notching a shoulder part 20c on the bellow part side of a recessed part 20 for fixing throughout a whole periphery, and a stress applied on the end part 20a on the bellows part side of the recessed part 20 by reducing the volume of the shoulder part 20c on the bellows part side of the recessed part 20 for fixing by the notch part 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resin joint boot, and more particularly to a bellows-shaped resin joint boot used for a constant velocity joint of an automobile and the like.

  A joint boot is attached to a joint of a drive shaft of an automobile or an industrial machine in order to hold encapsulated grease or prevent entry of dust or the like.

  FIG. 4 shows an example of a conventional joint boot 100. The boot 100 includes a large-diameter cylindrical portion 102 that is fitted to a housing portion of a constant velocity joint, and a small-diameter cylindrical portion 104 that is coaxially disposed apart from the large-diameter cylindrical portion 102 and is fitted to a shaft. The bellows portion 106 integrally connects the two, and is integrally formed by injection blow molding of a thermoplastic elastomer resin.

  On the outer peripheral surfaces of the large-diameter cylindrical portion 102 and the small-diameter cylindrical portion 104, fixing concave portions 108 and 110 for receiving clamping clamps are provided. Specifically, as shown in FIG. 5, the small-diameter cylindrical portion 104 is fixed to the outer peripheral surface of the shaft 122 by a ring-shaped tightening clamp 120 attached to the fixing recess 110. The large-diameter cylindrical portion 102 is also fixed to the outer peripheral surface of the housing portion in the same manner, although not shown.

  Conventionally, in this type of joint joint boot made of resin, there is a problem that when it is rotated in a state bent and deformed at a wide angle, a crack is generated in the fixing concave portion particularly in a small-diameter cylindrical portion, resulting in poor durability. is there. This is because the first peak portion 112 of the bellows portion 106 adjacent to the small-diameter cylindrical portion 104 is indicated by an arrow X0 as shown in FIG. This is due to repeated stress in the direction, and the stress caused thereby acts on the bellows portion side end portion 114 of the fixing recess 110.

  This invention is made | formed in view of such a point, and it aims at providing the resin-made joint boots which are excellent in durability by suppressing generation | occurrence | production of the crack in the recessed part for fixation.

  The resin joint boot of the present invention is a resin joint boot comprising a first tube portion, a second tube portion, and a bellows portion integrally connecting the two, and the outer peripheral surface of the first tube portion. A concave portion for fixing is provided, and a notch portion is provided in the shoulder portion of the concave portion on the bellows portion side.

  According to the resin joint boot of the present invention, the shoulder portion on the bellows portion side of the fixing recess is cut out to provide a cutout portion, whereby the volume of the shoulder portion is reduced. It is possible to relieve the stress applied to the end portion. Therefore, the durability of the resin joint boot can be improved.

  Since the problem of cracks due to such stress occurs particularly on the small diameter cylindrical portion side, the first cylindrical portion is a small diameter cylindrical portion, and the second cylindrical portion is a large diameter cylindrical portion arranged coaxially with the small diameter cylindrical portion. Is preferable.

  According to the resin joint boot of the present invention, by providing a notch in the shoulder portion side shoulder portion of the fixing recess, the volume of the shoulder portion is reduced, thereby the end portion of the recess portion on the bellows portion side. Therefore, the durability of the resin joint boot can be improved.

  Hereinafter, a resin joint boot 10 according to an embodiment of the present invention will be described with reference to the drawings.

  The resin joint boot 10 of the present embodiment is a thermoplastic elastomer resin boot that is attached to a constant velocity joint of an automobile. As shown in FIGS. 1 and 2, the small diameter cylindrical portion 12, the small diameter cylindrical portion 12, A large-diameter cylindrical portion 14 that is spaced apart and coaxially disposed, and a small bellows portion 12 and a bellows portion 16 that integrally connect the large-diameter cylindrical portion 14.

  The large-diameter cylindrical portion 14 has a short cylindrical shape that is fitted and fixed to the outer peripheral surface of the distal end portion of the cylindrical housing portion 1 in the constant velocity joint by a clamping clamp 2, and a ring-shaped clamping clamp 2 on the outer circumferential side. A fixing recess 18 extending in the circumferential direction is provided for receiving the.

  The small-diameter cylindrical portion 12 has a short cylindrical shape that is externally fixed to the outer peripheral surface of the shaft 3 protruding from the housing portion 1 by a clamping clamp 4, and is coaxial with the large-diameter cylindrical portion 14. Arranged to have a center line L. The small-diameter cylindrical portion 12 is also provided with a fixing recess 20 extending in the circumferential direction for receiving the ring-shaped tightening clamp 4 on the outer peripheral side.

  The bellows portion 16 is a bellows body having a circular cross section with a difference in diameter at both ends, and a grease filled space 22 is formed therein. The bellows portion 16 has a crest portion and a trough portion alternately arranged in order from the small-diameter cylindrical portion 12 side, such as a first crest portion 16a, a first trough portion 16b, a second crest portion 16c, a second trough portion 16d. It consists of a plurality of peaks and valleys formed in this way. The diameters of the crests and troughs are set so as to increase sequentially from the small diameter cylinder part 12 to the large diameter cylinder part 14, respectively.

  As shown in FIG. 3, in the cross-sectional shape of the small-diameter cylindrical portion 12 (cross-sectional shape passing through the boot center line L), the corners 20a and 20b on both sides in the axial direction of the fixing recess 20 are formed in curved surfaces. Further, a bellows portion side shoulder portion 20c, which is a portion rising from the bellows portion side corner portion 20a of the fixing concave portion 20a, that is, a portion radially outward, is cut out over the entire circumference. A notch 24 extending in the circumferential direction is formed.

  The notch 24 includes a vertical surface portion 26 that falls inward in the radial direction from the outer peripheral surface of the small diameter cylindrical portion 12, and an inclined surface portion 28 that extends from the inner end of the vertical surface portion 26 to the bellows side wall surface 20 d of the fixing recess 20. Consists of. The inclined surface portion 28 is inclined radially inward from the lower end of the vertical surface portion 26, that is, from the radially inner end toward the opening edge 12 a of the small diameter cylindrical portion 12. A convex curved surface is formed.

  In this embodiment, the vertical surface portion 26 is provided in the notch 24. However, without providing such a vertical surface portion, the taper is simply tapered from the outer peripheral surface of the small diameter cylindrical portion 12 to the bellows side wall surface 20d of the fixing recess 20. The notch 24 can also be formed by notching it into a planar or curved surface.

  As shown in FIG. 3, the small diameter cylindrical portion 12 is provided with a sealing ridge 30 projecting radially inward on the inner peripheral surface thereof. The sealing protrusion 30 is provided on the back side of the fixing recess 20 and is fixed by the clamping clamp 4 in a state of being fitted with the recess 5 provided on the outer peripheral surface of the shaft 3. The grease sealing space 22 is configured to ensure a sealing property on the small diameter cylindrical portion 12 side.

  In the resin joint boot 10 of the present embodiment configured as described above, the volume of the shoulder portion 20c is reduced by notching the bellows portion side shoulder portion 20c of the fixing recess 20 and providing the notch portion 24. Therefore, as shown in FIG. 3, even when the first peak portion 16a of the bellows portion 16 is repeatedly deformed in the direction indicated by the arrow X, the stress applied to the bellows portion side corner portion 20a of the fixing recess 20 is reduced. Alleviated.

  Therefore, even when the joint boot 10 is rotated in a state of being bent and deformed at a wide angle, the fixing recessed portion 20 is unlikely to crack in the small-diameter cylindrical portion 12, and thus has excellent durability.

  In order to confirm the above point, the joint boot of the present embodiment shown in FIG. 1 and the conventional joint boot shown in FIG. 4 are analyzed by a finite element analysis method (hereinafter referred to as FEM analysis). Was used to simulate the stress distribution when the joint angle (angle formed by the center line of the housing portion and the center line of the shaft) = 43 ° and 35 °.

  The results are as shown in Table 1 below, and in this embodiment having a cutout portion on the bellows side shoulder of the fixing recess in the small diameter cylindrical portion, the maximum stress amplitude value (bellows) applied to the bellows side end of the recess The amplitude value of the main stress acting in the direction along the cross-section R of the portion side end portion) was reduced as compared with the conventional example having no notch.

  Further, using a thermoplastic elastomer as a boot molding material, the joint boot of the embodiment shown in FIG. 1 and the conventional joint boot shown in FIG. 4 are molded, and the resulting resin joint boot is subjected to a durability test. It was. In the durability test, the resin joint boot was assembled to a constant velocity joint, and the ambient temperature was 100 ° C., the joint angle was 43 °, and the rotation speed was 500 rpm.

The results are as shown in Table 1 below, and the conventional joint boot was damaged from the bellows side corner of the fixing recess in the small-diameter cylindrical portion 25 hours after the start of the test. On the other hand, in the joint boot of the embodiment, the occurrence of breakage can be extended to 40 hours after the start of the test to achieve the target value of 30 hours, and the breakage is also a valley portion of the bellows part, and the small diameter cylindrical part There was no damage.

  In the above embodiment, the example in which the cutout portion 24 is provided in the bellows portion side shoulder portion 20c of the fixing recess 20 in the small diameter cylindrical portion 12 has been described, but instead of this, the fixing recess 18 of the large diameter cylindrical portion 14 is provided. A similar notch may be provided, and a similar notch may be provided in the fixing recesses 18 and 20 of both the small diameter cylindrical portion 12 and the large diameter cylindrical portion 14.

It is a half section half side view of the resin joint boot concerning one embodiment of the present invention. It is a half sectional view showing the mounting state to the constant velocity joint of the joint boot. It is the A section enlarged view of FIG. It is a half section half side view of the conventional resin joint boot. It is an expanded sectional view of the small diameter cylinder part in the conventional joint boot.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Resin joint boot 12 ... Small diameter cylindrical part 14 ... Large diameter cylindrical part 16 ... Bellows part 20 ... Fixing recessed part 20c ...... Bellows side shoulder part of fixing recessed part 24 ...... Notch part

Claims (2)

  A resin joint boot comprising a first cylindrical part, a second cylindrical part, and a bellows part integrally connecting the two cylindrical parts, the outer peripheral surface of the first cylindrical part having a fixing concave part, and the concave part A resin joint boot, characterized in that a notch is provided in the shoulder portion of the bellows portion. 2. The resin joint boot according to claim 1, wherein the first tube portion is a small-diameter tube portion, and the second tube portion is a large-diameter tube portion arranged coaxially with the small-diameter tube portion.

Images