GB2112852A - Flexible joints and seals therefor - Google Patents

Abstract

A flexible joint, comprising a socket member 11 and a shank member 13, includes a seal 20 of resilient material. When in its free state the seal is of tubular form with a flange 22 extending radially- outwardly thereof at one end. When fitted to the joint the seal is positioned on the shank member with its tubular portion 21 confined between the end portion 14 of the shank member, which is retained in the socket member, and abutment means 17 mounted on or formed integrally with the shank member. The abutment means is so spaced from the end portion 14 and the tubular portion 21 is of such length that, with the seal so fitted, the flange 22 is preloaded into sealing engagement with the peripheral edge portion 25 of the opening 26 of the socket member. <IMAGE>

Description

SPECIFICATION Flexible joints and seals therefor This invention relates to flexible joints and to seals therefor.

Hitherto the seals provided in many flexible joints, for example ball joints, for excluding foreign matter from the co-operating seating surfaces thereof have been so shaped as to necessitate the provision of a groove in one or other, or both, of the socket member of the joint and the member engaged with the socket member, to form a seating or seatings for the seal. Alternatively or additionally wire clips or other retaining devices have been required to hold the seal fast with respect to one or other, or both, of those members. Such provision has increased the cost of the flexible joints and in certain cases the fitting of the seals has sometimes been difficult and in consequence time-consuming.

The invention as claimed is intended to provide a remedy. It solves the problem of how to design a flexible joint and a seal therefor in which fitting of the seal to the joint can be effected rapidly and in which without the need for special retaining devices the seal affords a reliable means of excluding foreign matter from the interior of the joint.

According to the invention a flexible joint, comprising a socket member and a shank member having an end portion suitably retained in said socket member, is provided with a seal of resilient material which in its free state is of tubular form with a flange extending radially-outwardly thereof at one end and which when fitted to said joint is positioned on said shank member with the tubular portion thereof confined between said end portion and abutment means mounted on or formed integrally with said shank member, said abutment means being so spaced from said end portion and said tubular portion being of such length that with the seal so fitted said flange is preloaded into sealing engagement with the peripheral edge portion of the opening of said socket member.

By such preloading said flange may be deflected in the direction towards said abutment means.

Preferably the end face of said flange remote from said abutment means is provided with an annular recess so that an axially-directed circumferential lip is formed which overlaps said peripheral edge portion of said opening.

A seating provided in said socket member, and said end portion of the shank member which is co-operable with that seating, may be of complementary part-spherical shape.

Also according to the invention there is provided a seal suitable for a flexible joint, comprising a socket member and a shank member, and capable of resisting the ingress of foreign matter into the joint, said seal when its free state being of tubular form with a flange extending radially-outwardly thereof at one end, and being so adapted that when fitted to said joint its tubular portion is so confined as to cause said flange to the preloaded into sealing engagement with the peripheral edge portion of the opening of said socket member.

The advantages offered by the invention are mainly that said seal can rapidly be fitted to the flexible joint and the preload applied to said flange is sufficient to afford desired sealing around said peripheral edge portion of the opening of said socket member without the provision of special retaining devices and/or grooving associated with the seal.

Two ways of carrying out the invention are described in detail below with reference to drawings which illustrate two specific embodiments, in which: Figure 1 is a cross-sectional side elevation of a flexible joint and seal therefor in accordance with the first embodiment of the invention, Figure 2 is a view similar to that of Figure 1, but with the components of the joint in a different relative position, Figure 3 is a cross-sectional view, on a reduced scale, of the seal of Figures 1 and 2 in its free state, Figure 4 is a cross-sectional side elevation of a flexible joint and seal therefor in accordance with the second embodiment of the invention, Figure 5 is a view similar to that of Figure 4, but with the components of the joint in a different relative position, and Figure 6 is a cross-sectional view, on a reduced scale, of the seal of Figures 4 and 5 in its free state.

Referring to Figures 1 to 3, the flexible joint of the first embodiment includes a metallic socket member 11 which in this embodiment is formed integrally with the end portion of a bar 12 and a metallic shank member 13 having an end portion 14 of part-spherical shape. The interior of the socket member is so shaped as to retain a seating in the form of a flanged insert 1 5 of nylon material, the inner surface of which is of partspherical shape complementary to that of portion 14. The insert so receives the portion 14 as to afford the shank member 13 desired freedom of pivotal movement. The flexible joint thus formed is hence of ball-type and is suitable for example for use in a vehicle steering system (not shown).

The shank member is screw-threaded at 16 at its end portion remote from the end portion 14 for suitable attachment to an associated part of the steering system. Abutment means, in the form of a radialy flange 17, is formed integrally with the shank member immediately adjacent the screwthreaded portion 1 6. The lower face 1 8 of this flange is slightly coned as shown. The portion 19 of the shank member between the flange and the end portion 14 is of frusto-conical shape.

A resilient seal 20 for sealing the interior of the flexible joint against the ingress of foreign matter, for example grit, mud and water, is provided. As shown in Figure 3, the seal, in its free state, is basically of tubular form as at 21 and has a radial outward flange 22 at one end. This flange is so provided with an annular recess at 23 on its face remote from the abutment means that a circumferential lip 24 is formed which extends axially from the flange. In this embodiment the seal is of neoprene material.

In order to fit the seal 20 to the assembled flexible joint it is passed along the screw-threaded portion 16, flange first, and is then forced over the flange 17 of the shank member 13 until the tubular portion 21 is seated upon the frustoconical portion 1 9 of the shank member, the tubular portion then being confined between the end portion 14 and the flange 17. As such forcing of the seal into this position on the portion 1 9 is taking place the flange 22 is being urged with increasing force against the peripheral edge portion 25 of the circular opening 26 of the socket member 11 so that with the tubular portion 21 fully home on the portion 19 the flange 22 is maintained preloaded onto that edge portion 25.

Thus, during such fitting the seal is somewhat deformed due to the tubular portion being urged axially into the opening 26 and the flange being in consequence deflected in diaphragm-like manner.

As seen in Figure 1 the shank member 13 is in the upright position in which the seal 20 engages the bevelled edge 27 of portion 25 and the circumferential lip 24 laps over that portion onto the exterior part-spherical surface 28 of the socket member. Thus the flange 22 is substantially deflected in the direction towards the flange 17 and the seal, evenly folded over in the manner shown at 29, is fully seated around the socket opening 26 and provides reliable sealing.

On relative movement of the joint components 11, 1 3 away from the position shown in Figure 1 and in any direction about the centre 30 of the part-spherically-shaped end portion 14, for example to the position shown in Figure 2, the seal is somewhat distorted in that a greater degree of folding takes place on one side, as at 31, while on the other side the material of the seal is unfolded, being substantially flat as shown at 32.

Nevertheless, sufficient force is provided at the flange 22. due in part to the energy already stored in the material of the seal upon the force-fitting of the seal to the joint. as to maintain the flange preloaded against the entire peripheral edge portion 25 of the opening 26 and thus as to maintain the desired sealing. Upon such movement of the shank member a part of the flange 22 lifts up from the adjacent part of the bevelled edge 27 of portion 25. However here the flange 22 sealingly engages the adjacent part of the edge 33. Also the circumferential lip 24 is maintained lapping over onto the exterior partspherical surface 28 of the socket member.

Thus, whatever the angular position of the shank member with respect to the socket member. it is intended that at no time does any part of the flange periphery of the fitted seal lose sealing engagement with the socket member.

The preloading of the flange of the seal onto the peripheral edge portion of the opening of the socket member is predetermined by suitable choice of the grade of neoprene material used for the seal, by the overall length of the seal when in its free state, its wall and flange thicknesses and the distance between the flange 1 7 and the end portion 14 of the shank member 13.

With reference now to Figures 4 to 6, in the second embodiment of the invention the socket member, the shank member and the insert which receives the part-spherical end portion of the shank member, are identical with those of the first embodiment and bear the same reference numerals, 11, 13 and 1 5 respectively.

Like the resilient seal 20 of the first embodiment, the seal 41 of the second embodiment, which is shown in its free state in Figure 6, has a tubular portion 42, a radial outward flange 43 at one end of the portion 42 and an annular recess 44 on its face remote from the flange 17, so that a circumferential lip 45 is formed which extends axially from the flange 43.

However this seal differs from that of the first embodiment in that the lip 45 is provided with an annular rib 46 which in the free state of the seal extends radially-inwardly of the seal. The seal is of neoprene material.

As in the first embodiment, when the seal is forced onto the joint the tubular portion 42 is confined between the part-spherical end portion 14 and the flange 17. As this occurs the flange 43 is being urged with increasing force against the peripheral edge portion 25 of the circular opening 26 of the socket member 11 so that with tubular portion 42 fully home on portion 19, the flange 43 is maintained preloaded onto that edge portion 25.

As shown in Figures 4 and 5 the lip 45 is maintained lapping over beyond the edge portion 25 and the rib 46 is held in positive sealing engagement with the adjacent exterior partspherical surface 28 of the socket member.

In the position shown in Figure 4 of the components of the joint, the flange 43 is maintained preloaded against the entire peripheral edge portion 25, and around its entire periphery the rib is in sealing enagement with the surface 28. On relative movement of the joint components away from this position, for example to the position shown in Figure 5, a part of the flange 43 lifts up from the adjacent part of the bevelled edge 27 of portion 25. However here the flange 43 sealingly engages the adjacent part of the edge 33 and the rib 46 is maintained in sealing engagement with the surface 28.

Thus whatever the angular position of the shank member with respect to the socket member it is intended that at no time does any part of the rib 46 lose sealing engagement with the socket member.

Although in the embodiments above described with reference to the drawings each seal is of neoprene material, in alternative embodiments of the invention the seal may be of any other suitable resilient material affording ready fitment of the seal over the abutment means into the required position on the shank member.

Further, although in the embodiments above described with reference to the drawings an annular recess is formed in the flange of each seal member, in alternative embodiments no such recess may be necessary, or in other alternative embodiments it may be advantageous for a recess of other cross-sectional shape to be provided in the flange.

Again, although in the embodiments above described with reference to the drawings each abutment means comprises a flange formed integrally with the shank member, in alternative embodiments of the invention the abutment means may comprise a member which is suitably mounted, and retained in the required position, upon the shank member.

Finally, although in the embodiments above described with reference to the drawings each flexible joint is of ball-and-socket type, in alternative embodiments of the invention the co-operating seating surfaces of the flexible joint may be of suitable shapes other than spherical or part-spherical.

Claims (12)

1. A flexible joint, comprising a socket member and a shank member having an end portion suitably retained in said socket member, wherein a seal of resilient material is provided which in its free state is of tubular-form with a flange extending radially-outwardly thereof at one end and which when fitted to said joint is positioned on said shank member with the tubular portion thereof confined between said end portion and abutment means mounted on or formed integrally with said shank member, said abutment means being so spaced from said end portion and said tubular portion being of such length that with the seal so fitted said flange is preloaded into sealing engagement with the peripheral edge portion of the opening of said socket member.

2. A flexible joint as claimed in claim 1, wherein the end face of said flange remote from said abutment means is provided with an annular recess so that an axially-directed circumferential lip is formed which overlaps said peripheral edge portion of said opening.

3. A flexible joint as claimed in either claim 1 or claim 2, wherein a seating, provided in said socket member, and said end portion of the shank member which is co-operable with that seating, are of complementary part-spherical shape.

4. A flexible joint as claimed in claim 3, wherein said seating is in the form of a flanged insert suitably retained in the interior of said socket member.

5. A flexible joint as claimed in any one of claims 2 to 4, wherein said seal is provided with an annular rib which is carried by said axiallydirected circumferential lip and which is engageable with the exterior surface of said socket member.

6. A seal suitable for a flexible joint, comprising a socket member and a shank member, and capable of resisting the ingress of foreign matter into the joint, said seal when in its free state being of tubular form with a flange extending radiallyoutwardly thereof at one end, and being so adapted that when fitted to said joint its tubular portion is so confined as to cause said flange to be preloaded into sealing engagement with the peripheral edge portion of the opening of said socket member.

7. A seal as claimed in claim 6, wherein said seal is provided with an annular recess formed in that face of said flange at said one end of said seal so that an axially-directed circumferential lip is formed on said flange.

8. A seal as claimed in claim 7, wherein said seal is provided with an annular rib carried by said axially-directed circumferential lip and extending radially-inwardly of said seal when in its free state.

9. A flexible joint substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

10. A flexible joint substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings.

11. A seal substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

12. A seal substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings.