GB1583673A - Pin and socket joint - Google Patents

Description

(54) PIN & SOCKET JOINT (71) We, AUTOMOTIVE PRO DUCTS 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: The invention relates to pin and socket joints of the kind in which a pin is mounted in a socket member so as to be movable therein in both rotation and tilting or in rotation or tilting only. A gaiter of flexible material (commonly called a boot) seals an aperture in the socket member through which the pin extends. Such joints are commonly used in the suspension and steering linkages of motor vehicles and the boot has the dual functions of retaining grease lubricant within the joint and preventing contamination from road dirt and water.

Although pin and socket joints of this kind are greased on assembly, it is often thought desirable to add more grease on fitting to the vehicle or to replenish the grease at intervals during the service life of the joint, a grease nipple being provided for the purpose. This can cause problems if too much grease is injected or if the grease is injected too fast because the boot is liable to jump out of a groove where it engages the socket member or the pin or can even burst under pressure. Therefore it is known to provide a means by which grease can readily escape from the boot. Such a means is described in our British Patent Specification 1 477 649, in which a periphery of the boot, engaging with a groove in either the socket housing or the pin. has circumferentially spaced passageways, formed in the periphery of the boot. which provide a communication from the interior of the boot to the base of the groove in which the boot engages.

When such an escape means is provided with a boot having a bellows type construction there is tendancy for the said periphery of the boot to jump out of engagement with the groove especially when the pin is tilted relative to the socket.

The object of the present invention is to provide a pin and socket joint having a bellows type boot and which will permit greasing without the problems referred to.

According to this invention there is provided a pin and socket joint having an annular boot sealing an aperture in the socket member through which the pin extends, and the boot is of a bellows-like convoluted structure having peripheral portions sealing against the pin and the socket respectively one of the peripheral portions being provided with passageways to facilitate, in use, the escape of excess injected grease from the interior of the boot, wherein an external constricting ring is provided in the trough of one of the convolutions to limit the outwards distension of the boot under the internal pressure of the injected grease so as to limit the radially outward force exerted on said one of the peripheral portions as a result of such distension.

Preferably the ring is formed of a plastics material and conveniently it is located in the trough of the convolution adjacent the said one of the peripheral portions.

An embodiment of the invention will be described with reference to the accompanying drawings in which: Figure 1 is a ball joint according to this invention; Figure 2 is a sectional view of the boot utilised in Figure 1; With reference to Figure 1 and Figure 2 of the accompanying drawings a ball pin 11 comprises a shank 12 and head 13. The head 13 of the ball pin is housed in a socket member 14. The shank 12 of the ball pin projects through an aperture 15 in the socket member, the aperture 15 being such a size that the head 13 of the ball pin cannot pass through it.

The internal surface of the socket adjacent the mouth of the aperture 15 is hemispherical and co-operates with a like hemispherical surface on the head of the ball pin.

The ball pin is biassed against the internal surface of the socket by a spring 16 acting between a socket end plate 17 and a bottom bearing 18. The bearing 18 also has a hemi-spherical surface which co-operates with a like surface on the head 13 of the ball pin. The portion of the head 13 of the ball pin that co-operates with the bottom bearing is of a lesser diameter than that portion of the head 13 of the ball pin that cooperates with the internal surface of the socket.

A grease nipple 19 is screwed into the socket end plate 17 so as to facilitate the introduction of grease into the ball joint during servicing of the vehicle.

In use the ball pin rotates and tilts by virtue of its hemi-spherical surfaces cooperating with the like surfaces on the socket member and bottom bearing. The limitation on movement being the abutment of the shank 12 with the edge of the aperture 15.

The aperture 15 is sealed by a flexible rubber boot 21 of a annular configuration.

The boot 21 has a radially inner peripheral portion 22 and a radially outer peripheral portion 23, the radially inner peripheral portion sealing against the shank 12 of the pin and the radially outer peripheral portion sealing against the external surface of the socket member 14. The walls 24 of the boot 21 are convoluted to form a bellows-like structure that allows the walls of the boot to open and close as the pin tilts and or rotates.

The radially inner peripheral portion 22 has a beaded rim 25 which has two circumferential grooves 26 on the radially inner surface which seals against the ball pin, the beaded rim 25 also has a radially outer flap 27 which will abut against the housing of a component into which the pin 11 is secured.

The radially outer peripheral portion 23 also carries a beaded rim 28 which engages in a rectangular circumferential groove 29 in the external surface of the socket housing.

The boot 21 is held in position in the groove 29 by a spring ring 30 located in a circumferential external groove 33 in the beaded rim.

The radially outer peripheral portion of the beaded rim 28 has a plurality of circumferentially spaced passageways constituted by notches 31 each of which respectively provides a direct communication from the interior of the boot to the base of the groove 29 when the beaded rim 28 is located in the rectanguiar groove 29. A second plurality of spaced passageways constituted by channels 34 adjacent the side wall of the groove extends from the base of the groove to the exterior of the boot. Those notches 31 which provide a passageway from the interior of the boot to the base of the groove are aligned with those channels 34 which provide a passageway from the base of the groove to the exterior of the boot, and there is a continuous circumferential land 32 between the two sets of aligned passageways. This land 32 provides continuous seal with the base of the groove 29.

In use when excess grease, or a too rapid injection of grease causes a pressure build up within the boot, the excess grease, or air which the grease may be replacing, can escape from within the boot. The grease can pass from the interior of the boot to the base of the groove 29 via the notches 31. The pressure build up within the boot, and the weakening of the bead 28 in those areas adjacent the notches 31 and channels 34 causes the bead to expand radially outwards thus allowing grease to pass over the lands 32, and the exit via the aligned channels 34 to the exterior of the boot 21.

In order to prevent the bead 28 moving outwards to such an extent that it could be ejected from the groove 29 in the socket housing, a plastics ring 35 is fitted circumferentially around the exterior of the boot.

The ring 35 limits the distension of the boot under the internal pressure of the injected grease so as to limit the radially outward force exerted on the outer peripheral portion 23, through which the grease escapes, as a result of such distension. The ring 35 fits into a trough of the convolutions in the side wall 24 of the boot, and preferably into the trough of the convolution adjacent the bead 28.

WHAT WE CLAIM IS: 1. A pin and socket joint having an annular boot sealing an aperture in the socket member through which the pin extends and the boot is of a bellows-like convoluted structure having peripheral portions sealing against the pin and socket respectively, one of the peripheral portions being provided with passageways to facilitate, in use, the escape of excess injected grease from the interior of the boot, wherein an external constricting ring is provided in the trough of one of the convolutions to limit the distension of the boot under the internal pressure of the injected grease so as to limit the radially outward force exerted on said one of the peripheral portions as a result of such distension.

2. A pin and socket joint as claimed in Claim 1, wherein the ring is located in the trough of the convolution adjacent the said one of the peripheral portions.

3. A pin and socket joint as claimed in

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. socket member, the aperture 15 being such a size that the head 13 of the ball pin cannot pass through it. The internal surface of the socket adjacent the mouth of the aperture 15 is hemispherical and co-operates with a like hemispherical surface on the head of the ball pin. The ball pin is biassed against the internal surface of the socket by a spring 16 acting between a socket end plate 17 and a bottom bearing 18. The bearing 18 also has a hemi-spherical surface which co-operates with a like surface on the head 13 of the ball pin. The portion of the head 13 of the ball pin that co-operates with the bottom bearing is of a lesser diameter than that portion of the head 13 of the ball pin that cooperates with the internal surface of the socket. A grease nipple 19 is screwed into the socket end plate 17 so as to facilitate the introduction of grease into the ball joint during servicing of the vehicle. In use the ball pin rotates and tilts by virtue of its hemi-spherical surfaces cooperating with the like surfaces on the socket member and bottom bearing. The limitation on movement being the abutment of the shank 12 with the edge of the aperture 15. The aperture 15 is sealed by a flexible rubber boot 21 of a annular configuration. The boot 21 has a radially inner peripheral portion 22 and a radially outer peripheral portion 23, the radially inner peripheral portion sealing against the shank 12 of the pin and the radially outer peripheral portion sealing against the external surface of the socket member 14. The walls 24 of the boot 21 are convoluted to form a bellows-like structure that allows the walls of the boot to open and close as the pin tilts and or rotates. The radially inner peripheral portion 22 has a beaded rim 25 which has two circumferential grooves 26 on the radially inner surface which seals against the ball pin, the beaded rim 25 also has a radially outer flap 27 which will abut against the housing of a component into which the pin 11 is secured. The radially outer peripheral portion 23 also carries a beaded rim 28 which engages in a rectangular circumferential groove 29 in the external surface of the socket housing. The boot 21 is held in position in the groove 29 by a spring ring 30 located in a circumferential external groove 33 in the beaded rim. The radially outer peripheral portion of the beaded rim 28 has a plurality of circumferentially spaced passageways constituted by notches 31 each of which respectively provides a direct communication from the interior of the boot to the base of the groove 29 when the beaded rim 28 is located in the rectanguiar groove 29. A second plurality of spaced passageways constituted by channels 34 adjacent the side wall of the groove extends from the base of the groove to the exterior of the boot. Those notches 31 which provide a passageway from the interior of the boot to the base of the groove are aligned with those channels 34 which provide a passageway from the base of the groove to the exterior of the boot, and there is a continuous circumferential land 32 between the two sets of aligned passageways. This land 32 provides continuous seal with the base of the groove 29. In use when excess grease, or a too rapid injection of grease causes a pressure build up within the boot, the excess grease, or air which the grease may be replacing, can escape from within the boot. The grease can pass from the interior of the boot to the base of the groove 29 via the notches 31. The pressure build up within the boot, and the weakening of the bead 28 in those areas adjacent the notches 31 and channels 34 causes the bead to expand radially outwards thus allowing grease to pass over the lands 32, and the exit via the aligned channels 34 to the exterior of the boot 21. In order to prevent the bead 28 moving outwards to such an extent that it could be ejected from the groove 29 in the socket housing, a plastics ring 35 is fitted circumferentially around the exterior of the boot. The ring 35 limits the distension of the boot under the internal pressure of the injected grease so as to limit the radially outward force exerted on the outer peripheral portion 23, through which the grease escapes, as a result of such distension. The ring 35 fits into a trough of the convolutions in the side wall 24 of the boot, and preferably into the trough of the convolution adjacent the bead 28. WHAT WE CLAIM IS:

1. A pin and socket joint having an annular boot sealing an aperture in the socket member through which the pin extends and the boot is of a bellows-like convoluted structure having peripheral portions sealing against the pin and socket respectively, one of the peripheral portions being provided with passageways to facilitate, in use, the escape of excess injected grease from the interior of the boot, wherein an external constricting ring is provided in the trough of one of the convolutions to limit the distension of the boot under the internal pressure of the injected grease so as to limit the radially outward force exerted on said one of the peripheral portions as a result of such distension.

2. A pin and socket joint as claimed in Claim 1, wherein the ring is located in the trough of the convolution adjacent the said one of the peripheral portions.

3. A pin and socket joint as claimed in

Claim 1 or Claim 2, wherein the ring is a ring formed from a plastics material.

4. A pin and socket joint substantially as described herein and as shown in the accom panying drawings.