GB2038928A - Improved Ball Joint - Google Patents

Abstract

In a ball joint comprising a pair of annular seats 16, 18 received within a housing 12 and accommodating the ball head 22 of a ball pin 14 having its pin end 24 extending externally of the housing, the upper seat 18 is provided with a circumferential flange 32 resting on a shoulder 34 at a stepped upper end of the housing 12 and said upper end is closed by a cover 20 which compresses the flange 32 against the shoulder 34 both to create a dirt and-lubricant seal for the joint and also to prevent rotation of the upper seat 18 in the housing 12. <IMAGE>

Description

SPECIFICATION Improved Ball Joint This invention relates to ball joints.

In our Patent Specification No. 1,398,106 we disclosed a ball joint comprising a ball pin housing provided internally with a pair of opposed seats having inner surfaces of part spherical configuration receiving the ball end of a ball pin of which the other end extends externally from the housing, the region of the housing opposite that through which the ball pin extends being internally open, one of said seats, having an outer surface positioned within the housing opening, being provided on said outer surface with a plurality of circularly spaced upstanding ribs, said housing opening being closed by a cover secured to the housing and bearing against said ribs, said seat being thereby urged against the ball end to exert a preload thereon.Preferably an elastomeric sealing ring is interposed between the housing, its cover and the ribbed seat both to provide a lubricant and dirt seal and also to contribute reilience to the preload where required.

A sealing ring is necessary in the above described ball joint because an inadequate seal exists between the housing and the cover. It is one object of this invention, therefore, to provide a ball joint which does not require a separate sealing ring between the cover and the housing.

A further problem of the prior art ball joint lies in a tendency of the other of the seats sometimes to rotate in the housing and in order to prevent this, tongues or other projections have been provided on that seat to co-operate with corresponding recesses provided in the housing. It is a secondary object of this invention therefore to provide a ball joint in which said other seat can be prevented from turning without the necessity of providing special recesses for that purpose in the housing.

In accordance with the present invention, there is provided a ball joint comprising a housing having a substantially annular bore or similar interior chamber extending between opposed apertures of the housing, the housing being provided internally with a pair of opposed seats having part spherical internal surfaces for receiving and locating the ball head of a ball pin, the pin end of which extends out of one of said apertures, a cover closing the other aperture of the housing and bearing against circularly spaced upstanding ribs provided on the outer surface of zone of the seats, said seat being thereby urged against the ball head of the ball pin to exert a preload thereon, a circumferential flange on the outer surface of said seat, which flange is adapted to rest on a circumferential shoulder of the housing and has a thickness slightly greater than the depth of said shoulder such that the cover squeezes said flange against said shoulder when the cover is in position on the housing.

Preferably circumferentially spaced tongues and recesses are provided on said seats which interlock to prevent relative rotation between the seats.

By virtue of the invention, therefore, said other seat is prevented from rotating in the housing by means of the interlocking tongues and recesses on the seats, the ribbed seat being prevented from rotating by the circumferential flange which is held between the housing and the cover.

Furthermore a separate sealing ring is unnecessary since the flange, which is squeezed between the cover and the housing, provides the necessary lubricant and dirt seal. Preferably-the material of the ribbed seat is a cross-linked polyurethane which has sufficient resilience to exert the required preload but is also flexible enough to perform the function of a seal.

The invention is further described hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section through a ball joint in accordance with this invention; Fig. 2 is an exploded sectional view of parts of the ball joint illustrated in Fig. 1; and Figs. 3 and 4 show details of the flange on a part of a ball joint embodying the invention.

The ball joint 10 illustrated in Fig. 1 comprises a machined housing 12 which has a substantially annular bore 13 opening into an upper aperture 25 closed by cover 20. A ball pin 14 has a ball head 22 received within the housing 12 and a pin end 24 which extends out of the housing 12 through a lower aperture 26.

Within the housing 12 are arranged upper and lower seat members, respectively denoted 1 8 and 16, which are made of a resilient material such as cross-linked polyurethane and which have internally part-spherical seating surfaces for cooperation with the ball head 22 of the ball pin 14.

Alternatively one or both of the seats 1 6, 1 8 could be constructed from nylon or acetal or other suitable plastics material.

The upper seat member 1 8 has a substantially planar upper surface 28 from which extend circularly spaced, upstanding ribs 30. In Figs. 1 and 2 the ribs 30 are shown to be radially disposed on the seat 1 8. They may, however, be chordally or arcuately arranged on the upper surface 28 of the seat 1 8. During assembly of the ball joint, the upper aperture 25 is closed by the cover 20 which is arranged to bear against the ribs 30 to urge the seat member 1 8 into the housing. The seat member 1 8 is thus resiliently preloaded against the ball head 22 of the ball pin 14. The cover 20 is united with the housing by flanging the latter over the former at suitable points 36 or around the entire periphery thereof.

The upper seat member 18 is provided with a circumferential flange 32 which is of thickness a (see Fig. 2) and which rests on a shoulder 34 of the housing 12. The depth b (see Fig. 1) of the shoulder 34 is less than the thickness a of the flange 32 when the latter is in its free state.

Consequently, when the cover 20 is positioned on a second shoulder 33 of the housing 12, which shoulder adjoins but is radially outwardly of and axially displaced from the shoulder 34, and when the cover 20 is clamped down by the flanging at points 36, the flange 32 is firmly held by the cover but with the shoulder 33 limiting the axially inward movement and thus the compressive action of the cover 20. Thus a dual function of sealing the interior of the housing from the outside and of preventing the ribbed upper seat 1 8 from rotating within the housing is achieved by the single flange 32. In Fig. 2 the flange 32 is illustrated as having a substantially rectangular cross-sectional configuration.If a tighter grip on the flange 32 by the cover 20 and shoulder 34 is desired, that is, by increasing the difference between the thickness a and depth b, the periphery of the flange may be given one of the cross-sectional configurations illustrated at 32' and 32" in Figs. 3 and 4. In this way the thickened and rounded flange periphery is squeezed into the corners of the recess formed by the shoulder 34 and cover 20. If a correspondingly but uniformly thicker rectangular flange 32 were to be employed, which does not create any gaps into which it can deform, such thicker flange would tend to be squeezed out of the recess wherein it is received without additional sealing or holding capacity being produced.

Furthermore, the ribbed, upper seat member 18 is provided with downwardly projecting lugs 38 (see Fig. 2) and the lower seat member 1 6 with correspondingly arranged recesses 40. Thus the two seat members interlock whereby the lower seat member 1 6 is also prevented from rotating. As a consequence of this, the lugs 1 6a shown diagrammatically in dotted lines in Fig. 2, which have often been found necessary in the past for preventing the lower seat 1 6 from rotating, and corresponding grooves in the housing 12, can be omitted. ~~~~~~~~~~~~

Claims (5)

Claims

1. A ball joint comprising a housing having a substantially annular bore or similar interior chamber extending between opposed apertures of the housing, the housing being provided internally with a pair of opposed seats having part spherical internal surfaces for receiving and locating the ball head of a ball pin, the pin end of which extends out of one of said apertures, a cover closing the other aperture of the housing and bearing against circularly spaced upstanding ribs provided on the outer surface of one of the seats, said seat being thereby urged against the ball head of the ball pin to exert a preload thereon, a circumferential flange on the outer surface of said seat, which flange is adapted to rest on a circumferential shoulder of the housing and has a thickness slightly greater than the depth of said shoulder such that the cover squeezes said flange against said shoulder when the cover is in position on the housing.

2. A ball joint as claimed in claim 1, in which the interior of the housing is stepped adjacent said other aperture both to define said circumferential shoulder and also a second shoulder axially adjoining it, said second shoulder serving to receive said cover and to limit axial movement thereof in a direction into said housing.

3. A ball joint as claimed in claim 1 or claim 2, in which the seats are provided with circumferentially spaced complementary tongues and recesses which interlock to prevent relative rotation between said seats.

4. A ball joint as claimed in any one of claims 1 to 3, in which the flange is peripherally thickened.

5. Ball joint constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.