JPH0435616Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a bellows-shaped rubber boot that covers the outer periphery of a universal joint used in an automobile axle.

(Prior Art) A wheel shaft of an automobile is generally connected to a drive shaft via a universal joint, and rotationally driven by the drive shaft. Therefore, in automobiles using the above-mentioned universal joint, a rubber or other material is installed between the joint case and the connecting end of the drive shaft to prevent foreign matter such as pebbles or sand from entering the joint case housing the universal joint. The universal joint is protected by being covered with a bellows-shaped boot made of an elastic material, and a lubricant such as grease is sealed in the internal space of the boot to lubricate the universal joint.

By the way, as shown in FIG. 4, conventional rubber boots for automobiles of this kind usually have a large diameter part 3 fitted to the outer periphery of a joint case 2 attached to the wheel axle 1 side, and a large diameter part 3 fitted to the outer periphery of a drive shaft 4. A bellows portion 7 having a substantially constant wall thickness and having 3 to 6 peaks 6 is integrally formed between the small diameter portion 5 to be attached and the large diameter portion 3.
The outer periphery of the small diameter portion 5 is fastened and fixed with fastening members 8, 8' such as stop bands. (For example, see Utility Model Application Publication No. 59-29459.) (Problems to be solved by the invention) However, in such conventional rubber boots for automobiles, the drive shaft 4 and wheel axle 1 are rotated at 2400 rpm (equivalent to 240 km/h). When rotated at super high speeds,
The boot is tightened and fixed at both ends by fastening members 8 and 8' to prevent expansion in the radial direction, but on the other hand, there is no support in the radial direction near the center of the bellows part 7, so that vibrations due to eccentric rotation and centrifugation may occur. Since radial outward expansion is likely to occur due to force, the grease inserted into the internal space 9 tends to collect in the center. Therefore, a mountain portion 6 is formed in the center portion of the bellows portion 7.
In the case of a boot in which the groove is located, the grease concentrates in the inner groove of the crest 6, the center of the bellows part 7 expands due to centrifugal force, and the deviation of the grease in the circumferential direction increases the run-out, which can cause problems. There is a possibility that this may occur.

The present invention was developed with the aim of preventing the boots from swinging due to concentration of grease in the center of the bellows or from expanding due to centrifugal force, which conventional rubber boots for automobiles have.

(Means for solving the problems) The structure of the present invention to achieve the above purpose is explained as follows.
The diagram will be explained.

A rubber boot 15 for an automobile according to the present invention has a large-diameter portion 17 fitted to the outer periphery of a joint case 12 to which a wheel axle 11 is attached at one end, and the other end is housed within the joint case 12. It has a small diameter part 18 that is fitted to the drive shaft 13 connected via a universal joint 14, and the diameter of the peak part 19 gradually decreases from the large diameter part 17 to the small diameter part 18. It has a bellows part 20 shaped like this.

The bellows portion 20 of the automobile rubber boot 15 having the above-mentioned structure is formed into a flat portion 27 with no change in diameter at the center portion of the bottom portion.

Note that the flat portion 27 at the center of the bellows portion 20 is usually formed to have a length equivalent to at least the bellows pitch P, that is, a half pitch of the arrangement pitch of the ridge portions 19, and at least the inner surface of the flat portion 27. , a tapered portion 28 whose thickness gradually increases toward the center is integrally formed.

(Function) The automobile rubber boot 15 of the present invention having the above-mentioned configuration allows the drive shaft 13 and the wheel axle 11 to be rotated at 2400 r.p.
When the bellows part 20 is rotated at an ultra-high speed of m or more, the grease sealed in the space 16 inside the bellows part 20 concentrates toward the center of the bellows part 20, similar to a conventional rubber boot. The valley bottom part is formed as a flat part 27, and since there is no peak in this part and the diameter is small, the collision of grease concentrated in the tapered part 28 is prevented from occurring between the peaks 19 and 19. Since the grease is dispersed toward the inner surface, the centrifugal force that accompanies grease concentration is small, and the expansion of the rubber boot is suppressed.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a side sectional view showing an example of a rubber boot for an automobile according to the present invention, and FIG. 2 is an enlarged sectional view of section A in FIG. 1.

In these figures, 11 is a wheel shaft, 12 is a joint case fixed to the wheel shaft 11, and 13 is connected to the wheel shaft 11 by a universal joint 14 housed inside the joint case 12 so as to be rotatable at a constant speed. The drive shaft 15 is an automobile rubber boot which is a main part of the present invention and is provided between the joint case 12 and the drive shaft 13 and covers the universal joint 14.
A space 16 inside the rubber boot 15 is filled with grease for lubricating the universal joint 14.

The rubber boot 15 has a cylindrical large diameter portion 17 fitted on the outer periphery of the joint case 12 at one end thereof, and a cylindrical large diameter portion 17 fitted on the outer periphery of the drive shaft 13 at the other end. In addition, between the large diameter part 17 and the small diameter part 18, there is a mountain part whose diameter becomes smaller as it approaches the small diameter part 18 from the large diameter part 17 side. Bellows part 20 with 19a, 19b, 19c
is formed.

The large-diameter portion 17 and the small-diameter portion 18 have a concave groove 22 formed around the outer circumferential surface of the drive shaft 13, and a rib-like protrusion 21 having a chevron-shaped cross section is formed protruding from the inner circumferential surface on the small-diameter portion 18 side. Tightening bands 25, 2 are fitted into the circumferential grooves 23, 24 formed on the outer peripheral surface.
6, it is firmly fixed so that the grease sealed in the internal space 16 will not leak out.

The bellows portion 20 of the rubber boot 15 has a flat portion 27 whose central portion has a length corresponding to at least the bellows pitch P, that is, a half pitch (P/2) of the arrangement pitch of the mountain portions 19 at the bottom portion of the bellows. The flat part 27 is formed in a substantially cylindrical shape with the central axis O as a reference, and the large diameter is attached to the inner surface of the flat part 27, with the thickness of the central part being the maximum. A tapered portion 28 whose wall thickness gradually decreases as it approaches the portion 17 and the small diameter portion 18 is integrally molded.

Note that the tapered portion 28 imparts the required rigidity to the flat portion 27, so as shown in FIG. 3, a rib-shaped tapered portion 28' is also provided at the center of the outer surface to further increase the rigidity in the circumferential direction. Although it is possible to provide the tapered portion 28 on the inner surface side, it is particularly important to provide the tapered portion 28 on the inner surface side because the grease that concentrates on the flat portion 27 is easily dispersed back and forth. In addition, the taper part 2
The shapes and sizes of the bellows parts 8 and 28' are appropriately set so that the rigidity against expansion in the radial direction and bending in the longitudinal direction is greater than that of the other bellows parts 20.

The rubber boot for automobiles of the present invention has the above-mentioned configuration. Next, to explain its function, first, the drive shaft 13 and the wheel axle 11 are
When rotating at an ultra-high speed of 2400r.pm or higher, the grease sealed in the internal space 16 will cause the bellows part 2 to
When the grease moves to the center of 0, the centrifugal force generated by the rotation collides with the flat portion 27 and tries to push the flat portion 27 outward in the radial direction.

At this time, the flat part 27 has increased rigidity against expansion and bending due to the presence of the tapered parts 28 and 28', and the inner surface is inclined on both sides at an angle with respect to the direction of centrifugal force action. The grease is distributed along the inner surface toward the large-diameter portion 17 and the small-diameter portion 18, thereby preventing vibration in the central portion due to grease concentration.

(Effects of the invention) As described above, in the automobile rubber boot of the present invention, the center part of the bellows part is formed into a flat part having a length equivalent to at least half the pitch of the bellows part at the bottom part, and the peak part is formed in the center of the bellows part. Since the diameter of the flat part is set to the small diameter of the bottom part, even if the internal grease concentrates in the center during ultra-high speed rotation, the flat part and grease will not be present. The centrifugal force that acts is smaller than before, which prevents the grease from deforming due to centrifugal force, and also disperses colliding grease in the front and rear directions, preventing damage due to vibration of the bellows part and extending the life of the rubber boots. Demonstrates excellent effects.

Moreover, since a tapered part is formed on at least the inner surface of the flat part at the center of the bellows part, the thickness of which gradually increases toward the center, the rigidity against expansion and bending of the flat part is increased, and the grease that collides with the flat part is increased. This can be expected to have the effect of smoothing the branching, further promoting its dispersion, and, in combination with the reduction in centrifugal force due to the presence of the flat portion, preventing deformation of the central portion of the rubber boot.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a rubber boot for an automobile according to the present invention, Fig. 2 is an enlarged sectional view of section A in Fig. 1, and Fig. 3 is a sectional view showing another embodiment of the flat part.
FIG. 4 is a side sectional view showing a conventional rubber boot for automobiles. 12...Joint case, 13...Drive shaft, 14...
... Universal joint, 17 ... Large diameter part, 18 ... Small diameter part, 19 ... Mountain part, 20 ... Bellows part, 27 ... Flat part, 28, 28' ... Tapered part, P ... Bellows pitch .

Claims (1)

[Scope of utility model registration request] The drive shaft and the joint case are connected via the universal joint, and the joint is attached to cover the universal joint, and extends from the large diameter part fixed to the joint case to the small diameter part fixed to the drive shaft. , a rubber boot for an automobile having a bellows portion formed such that the diameter of the peak portion becomes gradually smaller, in which the center portion of the bellows portion is formed into a flat portion having a length equivalent to at least half the pitch of the bellows pitch at the bottom portion thereof; A rubber boot for an automobile, characterized in that a tapered part is formed on at least the inner surface of the flat part, the thickness of which gradually increases toward the center of the flat part.