GB2099909A - Ball and socket joints - Google Patents

Abstract

A ball and socket joint incorporates a housing 11, a ball member 14 within the housing and a bearing 18, 19 of plastics material interposed between ball and housing. Rotation of a bearing part 19 in housing 11 is resisted by a tapered lip 27 on the bearing which, when a retainer ring 21 is clamped down on to a shoulder 22 has its edge nipped in the corner of the interior of the housing at the inner edge of the shoulder 22. Figure 2 shows the assembly prior to this clamping operation and to retain the clamped condition, the rim 23 of the housing is subsequently spun in to hold the retainer ring 21. <IMAGE>

Description

SPECIFICATION Ball joint anti-rotation lip The invention relates to ball and socket joints and particularly but not exclusively to such joints for use in steering or suspension linkages of motor vehicles.

Atypical ball and socket joint incorporates a housing, a ball pin with a ball disposed within the housing a shank extending out through an opening in one end ofthe housing and a bearing of plastics material located within the housing and providing a spherical bearing surface to allow universal angular movement of the ball pin. It is convenient for the bearing to be made in separate upper and lower parts. It is then necessary to ensure that neither part of the bearing rotates in the housing because this could interfere with correct operation of the joint. It is possible to provide interlocking fingers between the two parts of the bearing to ensure that if one part is otherwise held against rotation the other part is also held. It remains to provide an effective low cost means to hold the first part against rotation.

According to the present invention there is provided a ball and socket joint of the kind comprising: a housing; a ball pin with a ball disposed within the housing and a shank extending out through an opening in the housing; a bearing of plastics material within the housing and providing a spherical bearing surface to allow universal angular movement of the bail pin, the bearing being retained within the housing by a retainer ring having a retaining face located against a shoulder in the housing and also bearing on an end face of the bearing, characterised in that the bearing has a tapered lip surrounding said end face such that on assembly of the joint the edge of the lip is nipped between the retainer ring and the housing. By this means, an anti-rotation feature can be provided in what is otherwise a conventional ball joint simply by a slight modification of the bearing.

In practice, in assembly of the joint, the bearing ring is clamped down towards its shoulder, at the same time compressing the bearing further into the housing. The flexibility of the material and the taper of the lip tend to cause the lip to be forced into the bearing but a small edge of the lip becomes caught in the junction between the shoulder and the retaining ring. This is sufficient to retain the bearing against rotation.

It had previously been proposed to provide a flange on the bearing which is clamped between the retainer ring and the shoulder but such a flange of necessity prevents positive metal to metal seating of the retainer ring on the shoulder.

Preferably the bearing ring is located against the shoulder by inward deformation of part ofthe housing beyond the retainer ring.

The bearing may be formed in two parts, in which case one part is held against rotation as specified above while the other is held against rotation by interlocking formations between the first and second bearing parts.

Preferably the opening through which the pin projects is the opening through which the bearing is inserted and held within the housing so that the pin projects through the bearing ring. Alternatively, the invention could be used in a joint of the kind in which the ball pin projects through an opening in one end of the housing whereas the ball pin and bearing are inserted into the housing through an aperture in the opposite end thereof. In this latter case, the bearing ring may be in the form of a disc acting as a closure for the opening.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which Figure 1 is a cross-section through an assembled ball joint in accordance with the invention but in which the antirotation feature of the invention is not evident due to deformation of parts of the ball joint during assembly; Figure 2 shows a part of the joint of Figure 1 on a much enlarged scale and with components of the joint in a partly assembled condition; and Figure 3 is a view corresponding to Figure 2 after completion of assembly of the joint.

First of all, the general nature of the ball joint will be described with reference to Figure 1 but without reference to the anti-rotation feature of the invention. The anti-rotation feature will then be described in relation to Figure 2 and 3.

The ball joint shown in Figure 1 incorpoates a forged steel housing 11 having a flange 12 by means of which the housing can be mounted to a part of a motor vehicle. A ball pin 13 incorporates a spherical ball member 14, a tapered portion 15 for insertion in a corresponding taper in another component of a motor vehicle and a threaded portion 16 for receiving a nut to hold the ball pin in this taper. The ball member 14 is enclosed within a part-spherical interior 17 of the housing 11. A part spherical bearing 18, 19 is formed in two parts and is arranged within the housing in engagement with both the ball 14 and the housing 11 so that it provides for universal angular movement of the ball pin 13 with respect to the housing 11.

The opening in the housing through which the ball pin 13 projects is also an opening through which, on assembly, the ball member 14 and the bearing 18, 19 can be inserted into the housing. Bearing member 18 has a part-spherical outer surface as well as its part spherical inner surface so that it mates with a part spherical surface within the interior of the housing.

In contrast, the bearing member 19 has a cylindrical outer surface corresponding to a parallel sided outer cylindrical part of the interior of the housing. This cylindrical shape permits simple assembly of the joint whilst allowing the bearing 19 to be supported with respect to the sides of the housing. A retainer ring 21 has a retaining face 28 which seats on a shoulder 22 of the housing and also bears against an end face ofthe bearing member 19 in order to hold the ball 14 and bearing 18, 19 within the housing.

The retainer ring 21 is itself held in position by The drawing(s) originally filed was/were informal and the print here reproduced is taken from a laterfiledformal copy.

inward deformation of a rim 23 of the housing.

A flexible dust seal 24 seals the interior of the ball joint against ingress of moisture and dirt and also helps to retain lubricant in the ball joint.

The two bearing members 18 and 19 have interlocking recesses 25 and projections 26 which prevent relative rotation between the two bearing members. However, there can still be a tendency for both bearing members to rotate together within the housing. Such rotation can be detrimental to ball joint because the inter-engaging faces ofthe housing and bearing are not designed for relative sliding movement. A means in accordance with the invent tion, for providing resistance to relative rotation between the bearing 18, and the housing 11 will now be described with reference to Figure 2 and 3.

Figure 3 simply shows a part of the ball joint of Figure 1 in an assembled condition but on a much larger scale. Figure 2 shows the same ball joint immediately prior to final assembly. As shown in Figure 2, the bearing member 18, the ball member 14 and the bearing member 19 have all been inserted into the housing. The retainer ring 21 is also shown generally in position except that it has not been forced down into engagement with seat 22.

In accordance with the invention, the end face 26 of the bearing member 19 against which the retainer ring can be engaged is provided around its outerperiphery with a tapered and generally triangular lip 27. As shown in Figure 2, this lip projects over the shoulder 22 and when the ball member and bearing members are simply inserted into the housing restricts the depth within the housing to which the bearing member 19 is inserted. The procedure for final assembly of the ball joint is to supply an end load to the retainer ring 21 which is in a downward direction in the drawings as shown. The extent of this end load is not critical but it must be sufficient to compress the bearing members into the housing to such an extent that bearing end face 26 is substantially flush with shoulder 27.This forcing of the bearing into the housing is possible, despite the lip 27, because the material of bearing member 19 issuffi- ciently flexible and lip 27 is at a suitable angle to enable the lip to be deflected towards the ball member 14 and generally be compressed into the main body of the bearing member 19. However, a small edge of the lip 27 tends to remain nipped between the inner edge of shoulder 22 and the retaining face 28 on the under side of the retainer ring 21. For the purposes of illustration, this is represented diagrammatically in Figure 3 as a residual lip 29 which, in Figure 3, slightly spaces the retaining face 28 from the shoulder 22. In practice, the retainer ring 21 does tend to seat on the shoulder 22, leaving only a very small residual lip forced into the corner at the inner edge of the shoulder 22.The nip of this small residual lip is sufficient to hold the bearing member 19 against rotation and as previously explained, bearing member 18 is held against rotation with respect to bearing member 19.

Once the retainer ring 21 has been clamped down into position by the external applied force, an outer rim 23 ofthe housing is spun over to hold the retainer ring 21 permanently in position, as shown in Figure 3.

Because the retainer ring 21 seats directly on the shoulder 22, which would not be the case if the lip 27 were replaced by a positive flange, the degree of clamping together of the bearing part and ball member is controlled solely by various dimensions within the bail joint so that accurate control of these dimensions result in a suitably controlled friction torque between the ball and the bearing. Furthermore, the very effective anti-rotation feature for the bearing can be provided in an existing design of ball joint with very title modification to the design. The only modification required is to the bearing member 19 and that modification can be achieved with a very simple modification to a moulding tool.

Claims (4)

1. A ball and socketjointofthe kind comprising a housing; a ball pin with a ball disposed within the nousing and a shank extending out through an opening in the housing; a bearing of plastics material within the housing and providing a spherical bearing surface to allow universal angular movement of the ball pin, the bearing being retained within the housing by a retainer ring having a retaining face located against a shoulder in the housing and also bearing on an end face of the bearing, characterised in that the bearing has a tapered lip surrounding said end face such that on assembly of the joint the edge of the lip is nipped between the retainer ring and the housing.

2. A ball and socket joint as claimed in claim 1 wherein the retainer ring is located against the shoulder by inward deformation of a rim of the housing which extends beyond the retainer ring.

3. A ball and socket joint as claimed in claim 1 or claim 2 wherein the bearing is formed in two parts, one of which is held against rotation as specified in a preceding claim and the other of which is held against rotation by interlocking formations between the first and second bearing parts.

4. A ball and socket joint as claimed in any preceding claim wherein the opening through which the pin projects is the opening through which the bearing is inserted and held within the housing so that the pin projects through the retainer ring.