GB2496582A

GB2496582A - A ball and socket joint

Info

Publication number: GB2496582A
Application number: GB1119043.6A
Authority: GB
Inventors: Andrew Richard Boucher; David William Thomas Cameron
Original assignee: GOLDSMITH S COLLEGE
Current assignee: GOLDSMITH S COLLEGE
Priority date: 2011-11-04
Filing date: 2011-11-04
Publication date: 2013-05-22
Anticipated expiration: 2031-11-04
Also published as: GB2496582B; GB201119043D0

Abstract

A ball-and-socket joint is provided. The ball and socket joint has a lug 5 on one of the ball 1 and the socket 2 and a groove/ recess or housing 4 for the lug 5 on the other of the ball 1 and the socket 2. The groove/ recess or housing 4 is shaped to interact with the lug 5 to allow the axis of the ball 1 to tilt relative to the axis of the socket 2 in any radial direction whilst constraining the ball 1 relative to the socket 2 against twisting about the longitudinal axis of the joint. Further aspects allow for operation of the ball and socket joint

Description

Ball and Socket Joint

Field of the Invention

The present invention concerns ball and socket joints including, inter alia, joints of conduits for electrical cables or for rubber hosing, or even for a vehicular gear stick and may have a range of other applications.

Background of the Invention

In poise-adjustable support structures of electrical appliances, such as lamps that have facility to direct the lamp head in a wide range of directions, universal joints such as ball-and-socket joints are sometimes used. These joints can give the ability to direct the appliance with a very high degree of freedom of movement but that freedom can itself cause problems. The electrical cabling to the lamp head or other poise-adjustable electrical appliance can easily become damaged and may shear apart or pull away at the contacts if twisted excessively. An analogous problem can occur with systems that have flexible fluid delivery! pneumatic or hydraulic delivery hoses if a ball-and-socket joint is used in the mounting! conduit for the hose, where the hose can be damaged or occluded if twisted excessively.

Although there have been a number of attempts in the past to address the problem of damage to or occlusion of through-passing cables or hoses in ball-and-socket joints by introducing abutments! end stops in the ball-and-socket joint to stop the joint from executing a 3600 rotation these have had only limited success and generally lack the ability to effectively facilitate the universal tilting movement while limiting. It is a general objective of the present invention to address these short-comings and further and other objectives and benefits of the invention will be apparent from the following disclosure.

Summary of the Invention

According to a first aspect of the present invention there is provided a ball-and-socket joint that has a lug on one of the ball and the socket and a groove! recess or housing for the lug on the other of the ball and the socket, the groove! recess or housing being shaped to interact with the lug to allow the axis of the ball to tilt relative to the axis of the socket in any radial direction while constraining the ball relative to the socket against twisting about the longitudinal axis of the joint.

Particularly preferably the groove! recess or housing has sidewalls that define an arcuate path and particularly preferably this is configured to allow the axis of the ball to tilt relative to the axis of the socket.

Particularly preferably the lug is formed as an elongate lobe that extends in the axial direction of the joint, suitably from at or near the first end of the ball to at or near the second end of the ball. The lobe is preferably a raised segment of the ball and preferably has sidewalls that bulge centrally and which taper towards each other -preferably tapering towards each other at each end of the ball.

Preferably the lug is shaped and dimensioned to be closely accommodated by the shaped groove! recess or housing to guide! determine the path of movement for the shaped lug to follow.

According to a second aspect of the present invention there is provided a ball-and-socket joint that has a lug on one of the ball and the socket and a groove! recess or housing for the lug on the other of the ball and the socket, the groove! recess or housing being shaped to interact with the lug to allow the axis of the ball to tilt relative to the axis of the socket while constraining the ball relative to the socket to follow a restricted substantially linear path within the universal movement offered by the ball and socket joint.

The path may be arcuate and! or have one or more bends or gate legs -to, for example, replicate the set movement of a car's gear stick or to serve as a path to create a key I locking system. For the latter purpose the device may be adapted to have one or more latches! gates, which may, for example, be spring-loaded to move! latch into place to trap the lug at a region along the path. The latch! gate is preferably configured to be retractable by a retraction means and suitably the retraction means comprises a key so that only the possessor of the key is able to retract the latch! gate.

The groove serves as a shaped housing to pre-program! pre-determine a path of movement for the shaped lug to follow. The restricted path of movement defined by the groove within the universal movement offered by a ball and socket joint may be tailored during formation! moulding of the socket to suit any given application amongst a wide range of different applications. The configurations of the groove may be diverse and thus to facilitate, for example, modification! adjustment of a socket in post-moulding stages the socket may be assembled from a number of component parts and in particular the part of the socket that serves as the groove! housing for the lug may have multiple parts to allow for different positions! shapes of the groove! housing for the lug.

The bafl joint may incorporate one or more liners! inserts arid or coflars/ sleeves formed of any suitable materials to enhance the conditions! functioning of the joint.

A liner! sleeve may be provided between the ball head and socket and most preferably is made of nylon, HDPE, ceramics or other low friction material to avoid need for oU! lubricants for joint maintenance so that the joint may be dry and oil free and yet readily adjustable. This is particularly desirable where the joint is of metals! metal afloys to reduce risk of chafing et cetera. Conversely, an insert sleeve! liner may also be used to make the joint more resistant to movement. An example material for such a higher friction liner might be rubber or other eastomeric materias. The liner may optionally be provided as a separate component or as a coating ayer/ paint.

In one embodiment the socket may be made of two halves or three or more parts, optionally having the atorementioned insert sleeve(s) and! or shim (s) and pralerably the parts assemble together by friction fit, e.g. pushing/snapping together or by being fastened together, preferably by fixings, eg. screwing together.

Shims may be provided as inserts for the joint to optimise operation, most notably for when he joint may need to he opUmised to bear substanUal loads, For example, one or more shims may be provided that are removable so that when wear OCCUrS and the joint loosens, at east one of the shims can be taken out to tighten up the grip on the baR from the worn side.

Brief Description of the Drawings

Preferred embodiments of the invention will now be more particularly described, solely by way of example, with reference to the accompanying drawings in which: Figures IA to IE are views of the socket of a first preferred embodiment of the joint in which the socket has a shaped groove to guide movement of a lobe-like shaped lug on the ball for tilting of the axis of the ball in a wide range of directions, with Figure 1A being a top plan view, Figure lB and Figure 1C being first and second side elevation views and Figures 1D and 1E being perspective views of the socket; Figures 2A to 2D are views of the ball of the first preferred embodiment, with Figure 2A being a top plan view, Figure 2B and Figure 2C being first and second side elevation views and Figure 2D being a perspective view of the ball; Figures 3A to 3D are views of the assembled ball and socket joint of the first preferred embodiment, with Figure 3A being a top plan view, Figure 3B and Figure 3C being first and second side elevation views and Figure 3D being a perspective view of the assembled joint; Figures 4A to 4E are views of the socket of a second preferred embodiment of the joint in which the socket has a wide, shaped groove that allows for up to 180° twist at the joint in addition to allowing for the range of angle-poise tilting motion, with Figure 5A being a top plan view, Figure 5B and Figure 5C being first and second side elevation views and Figure 5D and 5E being perspective views of the socket; Figures 5A to 5D are views of the assembled ball and socket joint of the second preferred embodiment, with Figure 5A being a top plan view, Figure 5B and Figure 5C being first and second side elevation views and Figure 5D being a perspective view of the assembled second embodiment of joint; Figures 6A to 6E are views of the socket of a third preferred embodiment of the joint in which the socket has a narrow channel groove that determines a more limited, gated movement at the joint, with Figure 6A being a top plan view, Figure GB and Figure CC being first and second side elevation views and Figure CD and CE being perspective views of the socket; Figures 7A to 7D are views of the ball for this third embodiment, where the lug has a compact rounded edged circular cylindrical form, with Figure 7A being a top plan view, Figure 7B and Figure 7C being first and second side elevation views and Figure 7D being a perspective view of the ball; and Figures BA to 8D are views of the assembled ball and socket joint of the third preferred embodiment, with Figure 8A being a top plan view, Figure 8B and Figure 8C being first and second side elevation views and Figure 8D being a perspective view of the assembled third embodiment of joint.

Description of the Preferred Embodiment

In the illustrated first preferred embodiment shown in Figures 1A to 3D the ball and socket joint is configured as a conduit for electrical cables (or hose) such as, for example, in a universal joint of an angle-poise lamp and it comprises a ball 1 and socket 2. Each of ball 1 and socket 2 has a respective conduit passage therethrough configured so that the passages are end-to-end and contiguous in use and the passages can be positioned to axially align with each other or so that the axis of one is inclined relative to the axis of the other by up to 450 or more in any radial direction. The ball 1 and socket 2 of the joint may each be moulded of plastics such as of nylon or polypropylene or may be formed in a metal or alloy or be a composite of materials.

The ball 1 has an integrally formed tubular circular cylindrical stem la and a substantially spherical ball head lb with the conduit passage ic passing through the stem la and ball head lb. The socket 2 of the joint has an integrally formed tubular circular cylindrical stem 2a and socket head 2b with a socket recess 2c that has a spherical concave surface 2d onto which the spherical convex surface of the ball head lb seats in use. The spherical concave surface 2d converges over the rear of the ball head lb when the ball head lb is in place whereby the ball 1 is held captive in the socket 2.

The socket 2 in this first embodiment has a shaped groove 4 that runs from a first end 2e of the socket recess 2c to a second end 2f, opening into the stem 2a. The shaped groove 4 has a pinched waist region 4a partway along its length and which is located closer to the first end 2e than the second end 2f. The pinched waist region 4a can serve as a fulcrum region about which the longitudinal axis of the ball 1 can tilt for angle-poise adjustment. Towards the second end 2f of the socket recess 2c the groove 4 flares wider than at the first end 2e to accommodate the large crown of the ball head lb as the ball 1 tilts to is extreme tilt positions.

As illustrated in Figures 2A to 2D, the ball head lb has a lobe-like shaped protruding lug 5 that is formed as a raised segment of the ball 1. This lobe-like lug projects into the groove 4 in use. The lug 5 is laterally constrained by the sidewalls of the groove 4. The lug 5 is an elongate lobe that extends in the axial direction of the joint from at or near the first end of the ball head lb to at or near the second end of the ball head lb and has curving sidewalls that bulge substantially centrally of the length of the lobe and which taper towards each other at each end of the ball head lb. When the joint is assembled as in Figures 3A-D the ball head lb is held captive in the recess 2c of the socket 2, with the lug 5 engaged in the groove 4 and constrained between the close opposing sidewalls of the pinched waist region 4a and thus constrained to prevent twisting about the longitudinal axis of the joint.

The joint 1, 2 does, however, retain full universal poise adjustment freedom of movement in any radial direction, tilting up to its predetermined maximum angle of tilt.

Turning now to the second embodiment of Figures 4A to SD, the joint in this embodiment has the same balI 1 as the first embodiment, with the same lobe-like lug 5, but has a modified socket 2. The modified socket 2' differs from that of the first embodiment in that the groove 4' of the recess 2c' of the socket 2' is widened, removing the narrow waisted region 4a and locating the sidewalls of the groove spaced apart by a separation that is greater than the width of the lobe-like lug 5 where it bulges laterally. Indeed the illustrated lobe-like lug 5 is a segment that is of the order of 1 o° of arc (radiating from the axis of the joint) at its widest whereas the groove 4' is greater than 1800 of arc wide at its widest. Accordingly when the ball 1 is fitted in the socket 2' the lobe-like lug 5 is free to move not only for universal tilt movement at the joint but also to move throughl8o° of arc radially around the axis of the joint -ie allows a limited twist about the longitudinal axis of the joint rather than the substantially zero twist allowed by the first embodiment.

This ball and socket joint can be used to substantially replicate the restricted movements as demonstrated in the human body, for example the shoulder joint and could thus be used as a prosthetic joint for a human or animal or in a model or a robotic device.

Turning to Figures 6A to 8D, the third embodiment of ball and socket joint, like the preceding two embodiments has a lug 15 on the ball 11 and a groove 14 on the socket 12 shaped to interact with the lug 15 to allow the axis of the ball 11 to tilt relative to the axis of the socket 12. In this embodiment, however, the interaction of the lug 15 and groove 14 constrains the ball 11 relative to the socket 12 to follow a restricted, substantially linear path within the universal movement offered by the ball and socket joint. The groove 24 here guides the movement of the ball In the illustrated socket 12 of Figures 6A to 6E the path defined by the groove 14 extends transverse to the longitudinal axis of the joint in an arc around part of the circumference of the socket 12 (unlike the grooves 4, 4' of the preceding embodiments which extend in the direction of the longitudinal axis of the joint). The lug 15 on the ball 11 is not a lobe but rather is a small circular cylindrical lug with a rounded! chamfered tip. This lug 15 fits closely in the narrow linear groove 14, entering the groove 14 through an entry channel! leg 14a of the groove 14 at the first end 12e of the socket 12. The rounded lug 15 when fitted in the arcing groove 14 and rotated about the longitudinal axis of the groove 14 is guided by the groove 14 to follow the arc.

The groove 14 serves as a shaped housing to pre-program! pre-determine a path of movement for the shaped lug to follow. The restricted path of movement defined by the groove 14 within the universal movement offered by a ball and socket joint may be tailored during formation! moulding of the socket to suit any given application amongst a wide range of different applications. Potential general applications may include a joint to replicate! define the set movement of a car's gear stick or as a path to create a key or locking system and within those general applications the configurations of the groove 14 may be very diverse. To facilitate, for example, modification! adjustment of a socket in post-moulding stages the socket may be assembled from a number of component parts and in particular the pad of the socket that serves as the groove 14/ housing for the lug 15 may have multiple parts to allow for different positions! shapes of the groove 14! housing for the lug 15.

Indeed, just as in this embodiment the socket may, rather than simply an integral groove, comprise a housing component for the lug that is an assembly of multiple parts, this manner of construction may be implemented in any of the embodiments of the invention. The lug-housing part of the socket or the socket as a whole may be assembled from multiple parts allowing the fabrication of more complex shaped housings and sockets.