GB1566757A

GB1566757A - Ball and socket joints

Info

Publication number: GB1566757A
Application number: GB145/77A
Authority: GB
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1977-01-05
Filing date: 1977-01-05
Publication date: 1980-05-08
Also published as: FR2376964A1; FR2376964B1; JPH0213769Y2; JPS5395959U

Description

(54) BALL AND SOCKET JOINTS (71) We, AUrOMOTIVE PRorucrs LIMITED, a British Company of Tachbrook Road, Leamington Spa, Warwickshire, CV31 3ER, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to ball and socket joints for automobiles and more particu Early to the type of joint utilised in steering systems.

According to this invention there is provided a ball and socket joint for use in automobile steering systems and having a substantially cup shaped housing which is lined b a bearing socket in which the ball of the pinis pin is rotatable, the socket being a snap-fit on the ball of the ball pin so as to support said ball on both sides of an equator normal to a polar axis constituted by the longitudinal axis of the cup shaped housing; and an end cap resiliently loaded into contact with the ball so as to exert a friction torque control on the ball up to a limit determined by wear of the bearing surfaces of the joint, at which limit the cap is arrested by an abutment limiting movement of the cap towards the ball.

Conveniently the abutment is provided by the bearing socket.

Preferably a portion of the end cap extends along said longitudinal axis into the bearing socket so as to align the end cap with respect to the socket.

Conveniently the bearing socket has slots extending longitudinally therein which allows the wall of the socket to flex on fitting around the head of the ball pin and the end cap has projections which co-operate with the slots so as to prevent rotation of the end cap.

Preferably the bearing socket has an annular flange which is trapped between the housing and a closure which seals the mouth of the cup shaped housing so as to prevent relative rotation of the bearing socket about the longitudinal axis.

One embodiment of this invention will now be described by way of an example and with reference to the accompanying drawings in which: Fig. 1 is a section through a ball and socket joint according to this invention; Fig. 2 is a bearing socket as utilised in the ball and socket joint illustrated in Fig. 1; and Fig. 3 is a modified bearing end cap, having projections that prevent rotation of the cap relative to the bearing socket.

With reference to Fig. 1 and Fig. 2, a ball and socket joint has a housing 11 which consists of two portions, a threaded shank 12 for attachment to the track rod of a vehicle steering system and a substantially cup shaped housing 13. The cup shaped housing 13 has an aperture 14 in its base opposite to the mouth 19 of the housing 13. An acetal resin or nylon bearing socket 18 is closely fitted within the housing 13 and has a similar aperture 29, in its base which aligns with the aperture 14 in the housing. A ball pin 16 has a spherical head 17 and a shank 15, the head 17 being received in the bearing socket 18 and the shank 18 protrudes through the apertures 29 and 14 so that it is substantially external to the housing 13. The bearing surface in the socket 18 has some lubricating grooves 20 moulded therein to aid distribution of grease.

The head 17 of the ball pin is capable of limited universal angular rotation within the bearing socket. The limits to the rotation being determined by abutment of the shank 15 of the ball pin with edges of the aperture 14 through which it passes. The mouth 19 of the housing 13 is sealed by a closure 21 which is held in position by deforming the annular mouth of the housing member. The closure 21 seats on an internal ledge 22 adjacent the mouth 19 such that it traps an annular flange 23 of the bearing socket 18 between the body of the housing member 13 and the closure 21. This prevents the bearing socket 18 from rotating relative to the housing 13. The annular flange 23 is an integral part of the bearing socket and is adjacent the mouth thereof. The bearing socket wall adjacent the flange has a thickened portion 33, so that the closure 21 also seats on the thickened portion of the wall such that if the pin 16 is pushed into the housing 13 the socket 18 is supported on the closure by the thickened portion of the wall.

A bearing end cap 24 is urged into contact with those surfaces of the head 17 of the ball pin 16 which are not contacted by the bearing socket 18 and are away from the shank 15 of the ball pin. The bearing end cap 24 is so urged by a helical spring 25 acting between the closure 21 and the end cap 24. A washer 26 is interposed between the spring 25 and the end cap 24. The load exerted by the helical spring 25 onto the head 17 of the ball pin provides a torque control load which must be overcome before the pin can rotate in the socket.

The aperture 14 is sealed against the ingress of road dirt by a substantially annular elastomeric boot 27, which is fixed at its radially inner periphery to the shank 15 of the ball pin and at its radially outer periphery is fixed to the housing member 13.

The shank 15 is tapered to mate with a tapered bore in another steering component (not shown) and the end portion of the shank 15 is threaded to allow a locking nut 28 to be screwed onto the shank after attachment to the said other steering component.

The bearing socket 18 is supported by the closely fitting walls of the cup shaped housing member 13 and the co-operating ledge 34. The bearing socket provides a support and bearing surface for the head 17 of the ball pin 16. The bearing socket is so shaped that it provides support for the spherical head of the ball pin on both sides of the equator of the spherical head (shown on the line E-E in Fig. 1). The equator being in a plane normal to the polar axis constitutes the longitudinal axis of the cup shaped housing 13. The support for the head 17 of the ball pin which is provided by the portion of the bearing socket on the side of the equator near the mouth of the cup shaped housing 13 extends to between 10 and 40 as defined by imaginary lines of latitude on the surface of the head of the ball pin. The angles of 10 and 40 are defined by the angle subtended at the centre of the sphere between the equator and the imaginary line of latitude as shown in Fig.

1. More particularly the support should extend to between 20 and 30 of the imaginary lines of latitude.

Since the support for the head 17 of the ball pin provided by the bearing socket 18 extends on both sides of said equator the bearing socket must be fitted to the ball pin prior to assembly of the ball pin into the housing 13. The ball pin is assembled into the socket 18 by passing the shank 15 of the ball pin through the mouth of the socket 18 adjacent the flange 23 and then through the aperture 29 in the base of the socket 18. The walls 30 of the bearing socket 18 on the side of the equator near the mouth 29 have six axial slots 31 circumferentially distributed around the wall of the bearing socket so as to allow that portion of the walls to flex when the head 17 of the ball pin 16 is pushed home so as to be a snap fit in the socket 18.

The socket 18 is snap-over socket, and the walls of the socket are extended away from the bearing support surface to provide an annular ring which includes the thickened portion 33 of the walls, and forms the mouth of the socket. The bearing end cap 24 is axially aligned with the bearing socket 18 and has an annular flange 32 which is aligned with the annular mouth of the socket 18. A portion 38 of the end cap 24 extends axially into the mouth of the socket 18 to locate the end cap so that it is co-axial with respect to the socket 18. The side of the annular flange 32 away from the socket 18 provides an abutment for the washer 26 and hence the spring 25 on the end cap 24.

As is shown in Fig. 3, the end cap 24 can be modified to have one or more projections 37 which project through the slots 31 and allow for axial movement of the end cap relative to the bearing but prevent rotation therebetween.

When the ball and socket joint is first assembled there is an axial clearance between the flange 32 on the end cap 24 and the mouth of the socket 18. As the joint wears in use the spring 25 relaxes as it keeps the end cap 24 in contact with head 17 of the ball pin. After a predetermined amount of wear has taken place and there has been a consequential predetermined relaxation of the spring 25, the flange 32 will contact an abutment formed from the mouth of the socket 18. If further wear in the joint takes place the end cap 24 is no longer urged against the head 17 of the ball pin by the spring 25, but the spring load is taken on the bearing socket 18.

Consequently the torque control load is removed from the ball pin which will therefore feel relatively loose in the socket.

WHAT WE CLAIM IS:- 1. A ball and socket joint for use in automobile steering systems and having a substantially cup shaped housing which is lined by a bearing socket in which the ball of the ball pin is rotatable, the socket being a snap-fit on the ball of the ball pin so as to support said ball on both sides of an equator normal to a polar axis constituted by the longitudinal axis of the cup shaped housing;

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. adjacent the mouth thereof. The bearing socket wall adjacent the flange has a thickened portion 33, so that the closure 21 also seats on the thickened portion of the wall such that if the pin 16 is pushed into the housing 13 the socket 18 is supported on the closure by the thickened portion of the wall. A bearing end cap 24 is urged into contact with those surfaces of the head 17 of the ball pin 16 which are not contacted by the bearing socket 18 and are away from the shank 15 of the ball pin. The bearing end cap 24 is so urged by a helical spring 25 acting between the closure 21 and the end cap 24. A washer 26 is interposed between the spring 25 and the end cap 24. The load exerted by the helical spring 25 onto the head 17 of the ball pin provides a torque control load which must be overcome before the pin can rotate in the socket. The aperture 14 is sealed against the ingress of road dirt by a substantially annular elastomeric boot 27, which is fixed at its radially inner periphery to the shank 15 of the ball pin and at its radially outer periphery is fixed to the housing member 13. The shank 15 is tapered to mate with a tapered bore in another steering component (not shown) and the end portion of the shank 15 is threaded to allow a locking nut 28 to be screwed onto the shank after attachment to the said other steering component. The bearing socket 18 is supported by the closely fitting walls of the cup shaped housing member 13 and the co-operating ledge 34. The bearing socket provides a support and bearing surface for the head 17 of the ball pin 16. The bearing socket is so shaped that it provides support for the spherical head of the ball pin on both sides of the equator of the spherical head (shown on the line E-E in Fig. 1). The equator being in a plane normal to the polar axis constitutes the longitudinal axis of the cup shaped housing 13. The support for the head 17 of the ball pin which is provided by the portion of the bearing socket on the side of the equator near the mouth of the cup shaped housing 13 extends to between 10 and 40 as defined by imaginary lines of latitude on the surface of the head of the ball pin. The angles of 10 and 40 are defined by the angle subtended at the centre of the sphere between the equator and the imaginary line of latitude as shown in Fig. 1. More particularly the support should extend to between 20 and 30 of the imaginary lines of latitude. Since the support for the head 17 of the ball pin provided by the bearing socket 18 extends on both sides of said equator the bearing socket must be fitted to the ball pin prior to assembly of the ball pin into the housing 13. The ball pin is assembled into the socket 18 by passing the shank 15 of the ball pin through the mouth of the socket 18 adjacent the flange 23 and then through the aperture 29 in the base of the socket 18. The walls 30 of the bearing socket 18 on the side of the equator near the mouth 29 have six axial slots 31 circumferentially distributed around the wall of the bearing socket so as to allow that portion of the walls to flex when the head 17 of the ball pin 16 is pushed home so as to be a snap fit in the socket 18. The socket 18 is snap-over socket, and the walls of the socket are extended away from the bearing support surface to provide an annular ring which includes the thickened portion 33 of the walls, and forms the mouth of the socket. The bearing end cap 24 is axially aligned with the bearing socket 18 and has an annular flange 32 which is aligned with the annular mouth of the socket 18. A portion 38 of the end cap 24 extends axially into the mouth of the socket 18 to locate the end cap so that it is co-axial with respect to the socket 18. The side of the annular flange 32 away from the socket 18 provides an abutment for the washer 26 and hence the spring 25 on the end cap 24. As is shown in Fig. 3, the end cap 24 can be modified to have one or more projections 37 which project through the slots 31 and allow for axial movement of the end cap relative to the bearing but prevent rotation therebetween. When the ball and socket joint is first assembled there is an axial clearance between the flange 32 on the end cap 24 and the mouth of the socket 18. As the joint wears in use the spring 25 relaxes as it keeps the end cap 24 in contact with head 17 of the ball pin. After a predetermined amount of wear has taken place and there has been a consequential predetermined relaxation of the spring 25, the flange 32 will contact an abutment formed from the mouth of the socket 18. If further wear in the joint takes place the end cap 24 is no longer urged against the head 17 of the ball pin by the spring 25, but the spring load is taken on the bearing socket 18. Consequently the torque control load is removed from the ball pin which will therefore feel relatively loose in the socket. WHAT WE CLAIM IS:-

1. A ball and socket joint for use in automobile steering systems and having a substantially cup shaped housing which is lined by a bearing socket in which the ball of the ball pin is rotatable, the socket being a snap-fit on the ball of the ball pin so as to support said ball on both sides of an equator normal to a polar axis constituted by the longitudinal axis of the cup shaped housing;

an end cap resiliently loaded into contact with the ball so as to exert a friction torque control on the ball up to a limit determined by wear of the bearing surfaces of the joint, at which limit the cap is arrested by an abutment limiting movement of the cap towards the ball.

2. A ball and socket joint as claimed in Claim 1, wherein the abutment is provided by the bearing socket.

3. A ball and socket joint as claimed in Claim 1 or Claim 2, wherein a portion of the end cap extends along said longitudinal axis into the bearing socket so as to align the end cap with respect to the socket.

4. A ball and socket joint as claimed in Claim 3, wherein the bearing socket has slots extending longitudinally therein which allow the wall of the socket to flex on fitting around the head of the ball pin, and the end cap has projections which co-operate with the slots so as to prevent rotation of the end cap.

5. A ball and socket joint as claimed in any one of Claims 1 to 4, wherein the bearing socket has an annular flange which is trapped between the housing and a closure which seals the mouth of the housing so as to prevent relative rotation of the bearing socket about the longitudinal axis.

6. A ball and socket joint as claimed in Claim 5, wherein the bearing socket has a thickened portion of the wall adjacent the flange such that if the ball pin is thrust into the housing the socket is supported by the thickened portion of the wall abutting against the closure.

7. A ball and socket joint substantially as claimed in Claims 1, 2, 3 and 5 as shown in the accompanying drawings.

8. A ball and socket joint substantially as claimed in Claims 4 and 6, and as shown in the accompanying drawings.