JP3191169B2 - boots - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boot for covering a constant velocity joint of an automobile.

[0002]

2. Description of the Related Art A constant velocity joint boot for an automobile is made of a thermoplastic elastomer, and has a large-diameter fixing portion and a small-diameter fixing portion which are tightly sealed to the outer ring and the shaft of the joint at both ends of a bellows portion. For example, those described in JP-A-62-52220 are known.

Most of such boots for constant velocity joints of automobiles are made of a thermoplastic elastomer. In general, thermoplastic elastomers have high rigidity and have poor adhesion to metal.Therefore, in boots made of thermoplastic elastomers, the fixing portion of the thermoplastic elastomer slips on the outer ring or shaft surface of the joint made of metal. easy. Therefore, at the time of startup, slippage occurs on the surface of the outer ring or shaft of the boot and the joint, and the boot falls off.

[0004]

To fix the boot made of a thermoplastic elastomer to a constant velocity joint, a special tightening band having a large tightening force is used to improve the adhesion. In an extremely low temperature atmosphere of about -40 ° C. or less, the rigidity of the thermoplastic elastomer is greatly increased, so that a large amount of slip occurs at a fixed portion of the boot with respect to the constant velocity joint. There was a drawback that the boots fell off.

The present invention relates to a boot for a constant velocity joint of an automobile, which is made of a thermoplastic elastomer. Even when used at cryogenic temperatures, a slip does not occur in a portion fixed to the joint and a high sealing property is maintained. It is an object of the present invention to provide a boot that can be used.

[0006]

The present invention has the following configuration to achieve the above object. That is, the boot according to the present invention is made of a thermoplastic elastomer, and has a large-diameter fixed portion and a small-diameter fixed portion that are tightly sealed to the outer ring and the shaft of the joint at both ends of the bellows portion, respectively. In a boot for use, one or both of the large diameter fixing portion and the small diameter fixing portion are provided with a plurality of inner projections extending in the axial direction and arranged in the circumferential direction on the inner periphery.

[0007]

According to the boot of the present invention, the inner periphery of one or both of the large diameter fixing portion and the small diameter fixing portion is provided with a plurality of inner surface projections extending in the axial direction and arranged in the circumferential direction. So, I attached the boots to the constant velocity joint,
If the fixing portion is tightened with a tightening band, a large anti-slip effect can be obtained with respect to the mounting portion of the constant velocity joint by the inner surface projection.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a boot for a constant velocity joint of an automobile. Reference numeral 1 denotes a boot. The boot 1 is a single layer or a multilayer of a thermoplastic synthetic resin elastomer such as a polyester, polyurethane, polyamide, or polyolefin, which is obtained by blow molding, injection molding or injection blow molding. It is molded into. As shown in FIG. 2, the boot 1 is formed by integrally forming a cylindrical large-diameter fixing portion 3 at one end of a bellows portion 2 and a cylindrical small-diameter fixing portion 4 at the other end. The bellows portion 2 of the boot 1 is formed by alternately forming peaks 5 and valleys 6, and the bellows 2 has a shape in which the peak diameter is sequentially reduced from the large diameter fixing portion 3 side to the small diameter fixing portion 4 side. None, the peak 5 has seven peaks, and the valley 6 has six valleys. An annular groove 7 having a concave angle is formed in a part of the valley 6 of the bellows 2. The thermoplastic synthetic resin elastomer constituting the boot 1 has a tensile modulus (JIS K6).
301) is an elastic material having a relatively large strength of 100 to 1000 kg / cm ² .

The large-diameter fixing portion 3 and the small-diameter fixing portion 4 are respectively formed with concave steps 8, 9 for mounting a tightening band (not shown). An annular projection 10 is formed on the inner periphery of the large diameter fixing portion 3 in the circumferential direction, and an annular groove 11 is formed on the outer periphery of a portion corresponding to the annular projection 10. An annular groove 1 is provided on the outer periphery of the large diameter fixing portion 3.
1, a concave portion 1 extending in the axial direction on both sides in the axial direction.
2 are formed at equal intervals in the circumferential direction, and an inner surface projection 13 is formed in the same direction as the inner periphery of a portion corresponding to each recess 12. The degree of protrusion of the annular protrusion 10 is larger than that of the inner protrusion 13.

The small diameter fixing portion 4 of the boot 1 also has an annular protrusion 10, an annular concave groove 11, and a concave portion 12 like the large diameter fixing portion 3.
And inner projections 13 are formed.

In order to mount the boot 1 on a constant velocity joint (not shown), a fastening tool (see FIG. 1) is attached to the concave step 8 of the large diameter fixing part 3 and the concave step 9 of the small diameter fixing part 4 of the boot 1 respectively. (Not shown), the boot 1 is inserted loosely into the shaft of the constant velocity joint from the large diameter fixing portion 3 side, and the large diameter fixing portion 3 is attached to the outer race and the small diameter fixing portion 4 is attached to the shaft. Make it inserted. Then, the fastener is fastened and fixed on the large diameter fixing portion 3 and the small diameter fixing portion 4.

In the process of tightening the large-diameter fixing portion 3 with a fastener, the annular projection 10 is deformed by being pressed by the outer ring, and the inner projection 13 is further deformed by being pressed by the outer ring. Is fixed. The deformation of the annular protrusion 10 and the inner surface protrusion 13 escapes into the annular groove 11 and the concave portion 12, respectively, and is absorbed. Therefore, the large diameter fixing portion 3 of the boot 1 is firmly fixed to the outer ring of the constant velocity joint with high sealing properties. Moreover, the annular protrusion 10 and the plurality of inner surface protrusions 13 are formed in directions perpendicular to each other, and the degree of protrusion of the annular protrusion 10 is larger than that of the inner surface protrusion 13. The anti-slip effect on the outer ring is great. On the other hand, the small diameter fixing portion 4 is also fixed to the shaft of the constant velocity joint in the same state as the large diameter fixing portion 3, so that the inside of the boot 1 maintains a high sealing property and has a large anti-slip effect on the shaft.

As described above, the boot 1 shown as an embodiment of the present invention is fixed to the constant-velocity joint with the large-diameter fixing portion 3 and the small-diameter fixing portion 4 with high sealing properties, respectively, and has a high anti-slip property. Since the effect can be obtained, even when the boot 1 is used at an extremely low temperature of about −40 ° C. or less, no slip occurs at the fixed portion with the constant velocity joint, and high sealing performance can be maintained.

[0014]

According to the present invention, there is provided a boot for a constant velocity joint of an automobile, which is made of a thermoplastic elastomer. Deterioration of the state of fixation of the boot, which is likely to occur sometimes, or fall of the boot can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an entire boot according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional front view of a part of a small diameter fixing portion in FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 2;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 boot 2 bellows part 3 large diameter fixing part 4 small diameter fixing part 5 mountain part 6 valley part 8, 9 concave step part 10 annular projection 11 annular concave groove 12 concave part 13 inner projection

Claims (1)

(57) [Claims] 1. A boot for a constant velocity joint of an automobile comprising a thermoplastic elastomer and having a large-diameter fixing portion and a small-diameter fixing portion which are tightly sealed at both ends of a bellows portion with an outer ring and a shaft of a joint, respectively. A boot characterized in that a plurality of inner projections are provided on the inner periphery of one or both of the large diameter fixing portion and the small diameter fixing portion so as to extend in the axial direction and are arranged in the circumferential direction.