GB2166815A

GB2166815A - Bellows to enclose pivotting joint

Info

Publication number: GB2166815A
Application number: GB08526057A
Authority: GB
Inventors: Kunio Takeuchi; Yoshihito Imura
Original assignee: Tokai TRW and Co Ltd
Current assignee: Tokai TRW and Co Ltd
Priority date: 1984-10-31
Filing date: 1985-10-22
Publication date: 1986-05-14
Also published as: DE3538617A1; JPS61109967A; KR940008830B1; GB2166815B; GB8526057D0; KR860003437A; AU595166B2; AU4907085A

Abstract

A bellows, 10, which can accommodate, pivotal movement, comprises a corrugated cylindrical body, wherein the radius of curvature of the crests 21 and valleys 22 varies continuously from end to end. <IMAGE>

Description

SPECIFICATION Bellows This invention relates to improvements in bel lows. It is a matter of common knowledge that a bellows is adapted for expansion and contraction in its axial direction and is formed in such a manner that a cylindrical body or a parison is obtained by injection molding, and that the bellows in the cylindrical form is then provided on its periphery with a plurality of corrugations. Such a bellows is preferably required not only to expand and contract in its axial direction but also to smoothly flex in its radial direction when it is employed such as to cover the perimeters of a shaft and another shaft swingingly connected thereto. To this end, it has heretofore been customary for a bellows of this kind to have a variation in its thickness or in the pitch of the corrugations on the periphery of the bellows in a plurality of steps, such as two or more steps.Variation in the wall thickness has, however, involved much difficulty since control is always required for the parison thickness. On the other hand, variation in the pitch of the corrugations of the bellows has also provided much difficulty since the positions of rocking points need to be in alignment with the steps.

One of the objects of the present invention is, therefore, to provide a bellows which removes the defects in the prior art as above referred to and is efficient in practical use.

The other object of the present invention is to provide a bellows in which the manufacture is simpler and smooth in terms of the movement in the axial and radial directions as compared with the conventional bellows in which the wall thickness of the corrugated cylindrical body varies and the pitch varies in a plurality of steps.

Briefly stated, to the above and other ends, the present invention provides a bellows having crests and valleys varied in angle and diameter from one end to the other of its corrugations.

The above and other objects, features and advantages of the present invention will become more apparent from the description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.

Figure 1 is a section of a preferred embodiment of the present invention which is embodied in a bellows as applied to a rack and pinion steering assembly; Figure 2 is a sectional view of the bellows shown in Fig. 1; Figure 3 is an end elevational view of the bellows; and Figure 4 is a sectional view taken along the line A-A of Fig. 2.

First referring to Fig. 1 of the drawing, the bellows of the present invention is shown as being applied to a rack and pinion steering gear assembly. In Fig. 1, reference numeral 1 denotes a housing. Disposed within the housing 1 are a rack and a pinion 3 in engagement with rack teeth 2a on the rack 2. The opposite ends of the rack have tie-rods 5 secured thereto by means of ball joints 4. The tie-rods 5 are connected to wheels (not shown) through suitable links (not shown). The pinion 3 is connected to one end of the steering shaft (not shown), the other end of which is connected to the steering wheel (not shown).

Thus, when the steering wheel is rotated, the pinion 3 rotates to axially move the rack 2 which meshes with the pinion to steer the associated wheels. Since this arrangement has been known in the art, detailed description thereof will be omitted here.

A bellows according to the present invention is generally shown by reference numeral 10 and is positioned to cover the ball joints 4. One end 11 of the bellows 10 is secured to the housing 1 while the other end 12 of the bellows is secured to the associated tierod 5. The detail of the bellows is more clearly shown in Fig. 2. The bellows 10 has a corrugated cylindrical body 20 positioned between the opposite ends 11, 12 thereof. The corrugated cylindrical body 20 includes a plurality of annular crests 21 spaced in the axial direction and a plurality of annular valleys 22 interposed between the adjacent crests 21.

The crests and valleys have diameters which constantly vary from one end 11 to the other end 12 of the body 20.

In the illustrated embodiment, as more clearly shown in Fig. 2, the angles of the crests 21 gradually decrease from one end 11 to the other end 12 and on the other hand, the angles of the valleys 22 gradually increase from one end 11 to the other end 12 of the body 20. When the crest angle is small, the distance or pitch between the crests is small and the rigidity of the bellows is accordingly lower than that of the bellows where the crest angle is great. And when the crest diameter is great, the thickness of the crest is smaller than with the smaller crest diameter.

With the above-mentioned construction and arrangement of the components of the bellows according to the present invention, when the bellows contracts from its free condition, the bellows begins to contract from the other end 12 towards the one end 11 and when the bellows expands from its contracted condition, the bellows begins to expand from the one end 11 towards the other end 12.

In the illustrated embodiment, the bellows is so disposed that the other end 12 or the less rigid end faces the ball joint 4. With this arrangement, the bellows can rock smoothly and is free of interference in the inner and outer peripheries because stroke components have little effect on the rocking movement.

As more clearly shown in Figs. 2 and 3, the end face 30 which interconnects the outer end 12 and the corrugated cylindrical body 20 is provided with reinforcing ribs 31 as shown in Figs. 3 and 4.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

Claims

1. A bellows having a corrugated cylindrical body including a plurality of annular crests provided about the outer periphery of said body in axially spaced relationship and a plurality of annular valleys defined by and positioned between said crests, said crests and valleys continuously varying in diameter from one end to the other end of said corrugated cylindrical body.

2. The bellows of Claim 1 wherein the angles of said crests gradually decrease from one end to the other end of the body and the angles of said valleys gradually increase from one end to the other end of the body.