GB2407844A

GB2407844A - Ball joint mechanisms

Info

Publication number: GB2407844A
Application number: GB0325881A
Authority: GB
Inventors: Christopher Summers; Len Russell
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-06
Filing date: 2003-11-06
Publication date: 2005-05-11
Also published as: GB0325881D0

Abstract

Ball joints are disclosed consisting of two hemispherical shells (41, 42) which may be clipped together (44) around a spherical or part spherical ball member (45). The shells define an aperture (71, 72) through which a stalk (46) connected to the ball member (45) passes. Stalk (46) may be connected e.g. to a support post (5) and one of the shells (42) may clip on to a tray member (1) to form an adjustable angle support stand.

Description

BALL JOINT MECHANISMS

This invention relates to ball joint mechanisms and particularly to ball joints which are used to enable the angular position of one item relative to another to be varied by overcoming internal friction in a ball joint, which internal friction is sufficient to hold the parts of the ball joint in fixed relative position under lesser applied forces.

A conventional ball joint consists of a ball on the end of a first member and a socket forming part of a second member, the socket being so dimensioned relative to the ball that the ball may be held captive within it. This is often achieved by splitting the socket into two equal parts with a parting line consequently corresponding to the diameter of the ball. The two halves of the socket can then be assembled around the ball, the degree of movement available to the ball depending upon the extent of the spherical surface on the inside of the socket. Even if the surface is only just greater than a hemisphere in size, the degree of freedom for the ball may still be very substantial, particularly if the ball has only a relatively thin stalk by which it is connected to one of the items to be joined via the ball joint.

We have now found that ball joints, which are of particular value in certain applications, may be produced easily and simply through plastics moulding and have a particular advantage in that they are quick and straightforward to assemble.

According to a first feature of the present invention, there is provided a ball joint consisting of a first component being an at least part spherical ball portion having a connecting stalk attached thereto, and a second component in the form of a socket formed of two hemispherical shells having mutually engageable clip means allowing the two shells to be clipped together to define a hollow spherical cavity into which the part spherical ball portion of - 2 the first component may fit and wherein at least one of the shells has an aperture through which the connecting stalk may pass.

Preferably, the relative sizes of the hollow spherical cavity and the part sphere or spherical section are such that when the two shells are clipped together, they form a tight fit around the spherical or part spherical ball portion of the first component, thus enabling the position of the ball to be adjusted relative to the second component simply by overcoming the frictional force between them, but where the position, once adjusted, remains held by friction until the frictional force holding the two components in position relative to one another is overcome. This is easiest achieved by manufacturing each of the components from resilient plastics materials, for example, ABS or HIPS. Alternatively, the fit may be looser, allowing for easier swivelling of the two components of the joint relative to one another, but where the components have formations which may inter-engage to hold the two components in a relatively fixed position - for example a protrusion on one component and a dip on the other into which the protrusion may be engaged, but from which, by the application of a force sufficient to distort the components slightly, it may be released. Several such formations may enable a corresponding number of defined relative positions to be taken up by the two components. In particular, part of the aperture may be in the form of a parallel-sided channel in which the stalk may slide with oppositely located pairs of low-profile bumps on the channel sides defining one or more specific positions for the stalk in the channel.

By careful design of the structure of the components and utilizing stateof the-art production machinery and know-how, and commercially available plastics materials, ball joints may be made very inexpensively which can be rapidly assembled, but which act effectively in practice to provide angular adjustability between, say, two other associated components, which can be set at an appropriate angle one to another simply and effectively, and where the angle can be changed by applying a force sufficiently great to overcome the friction between the spherical or part spherical ball and the spherical socket.

The degree of angular movement of the spherical or part spherical ball relative to the socket is determined by the extent (i.e. the size and shape) of the aperture. For example, the two hemispherical shells of the second component may when clipped together define a substantially Tshaped cutout enabling movement to occur essentially up and down and, at one end of the up and down movement, from side to side, but not at the other end.

The aperture may be formed in one or both shells constituting the second component.

A typical example of the use of a ball joint in accordance with the present invention is as the joint component in a variable position stand, for example for supporting a book, beverage container, or the like, at home, in the garden or at a beach or picnic site. Two examples of the use of a ball joint in accordance with the present invention in such a stand are illustrated by way of example in the accompanying drawings in which: Figure 1 is a general perspective view of a tray table/reading stand for use, e.g., indoors, in the garden, or on a beach.

Figures 2a, 2b and 2c are side, end and perspective views of a first portion of the second component of the ball joint shown in Figure 1.

Figures 3a, 3b and 3c are side, opposite side and perspective views of a second portion of the second component, of the ball joint shown in Figure 1, Figures 4a and 4b are side and end views of a first component of the ball joint shown in Figure 1, - 4 Figure 5 is an underneath perspective view of an alternative embodiment of the variable position tray table/reading stand, and Figure 6 is a diagrammatic section taken along the lines A-A in Figure 6.

Referring to Figure 1, this shows a perspective view of a reading stand/tray table unit which may be used as a beverage table and beverage container support. It comprises a tray portion 1 consisting of a generally flat base or wall with three upstanding edges and two resilient spring clips 2 adapted to hold and restrain, e.g., the pages of a book placed on the tray 1 from skipping over or from blowing about in the wind. Attached to the wall of the tray which bears the spring clips 2 is a fixed clip 3 as part of a ball joint 4, the ball joint 4 acting to enable the relative position between the tray 1 and a vertical support shaft 5, which is attached to a foot or stand or which may be driven into the ground or sand to a sufficient degree to give stability to the overall structure, to be adjusted. Beverage containers, e.g. plastics beakers of standard frusto-conical form, tumblers or wine glasses may be held firmly in two apertures 6 in tray 1.

The ball joint 4 consists basically of two components shown in Figures 2, 3 and 4 of the accompanying drawings. The parts shown in Figures 2 and 3 and generally denoted 10 and 19 respectively, make up the socket component and have mutually engaging tabs and cutouts 18 and 16.

Referring to Figure 2, this shows in side, end and perspective views a generally hollow hemispherical shell member 10 having a clip portion (3 on Figure 1) on its exterior containing three tabs 11, 12, 13. As can be seen, the tabs have wedge-shaped projections 15 on them and these can be engaged in corresponding apertures in the wall of the tray 1 to fix clip 3, which is mounted on the hemispherical shell member 10, firmly to the edge of the tray 1. - 5

The wall of the hemispherical shell member 10 is interrupted at intervals by four equally spaced cut-away portions 16.

These four cut-away portions 16 can be filled by the resiliently sprung ends of the tabs 18. Tabs 18 project from the second hemispherical shell member 19, which constitutes the other half of the second component, and which is shown in Figures 3a to 3c. As can be seen, the generally hemispherical shell member 19 has four tabs 18 equally spaced about its lower circular edge together with a cut-away generally T-shaped portion 20.

Figures 4a and 4b show a moulded member consisting of a part-spherical head 25 that is mounted on a neck 26 that in turn merges into a mounting post 27. Post 27 is a press fit inside the support leg (5 shown in Figure 1).

Protruding sideways from the neck 26 is a support tab 32 for a purpose to be described below.

Head 25 is so dimensioned that it may be held captive between the two hemispherical shells shown in Figures 2 and 3 whilst the neck which constitutes the stalk of the ball joint of the present invention passes through the cut away portion 20. The dimensions are so chosen that members 10 and 19 may be clipped together with head 25 fitting tightly between them.

The resilience of the plastics material from which the components are moulded is sufficient to enable the shells 10 and 19 to be clipped firmly around the part-spherical ball head 25 and the materials and surface finishes of the components are so chosen that when so clipped together, the part spherical head 25 can, once sufficient force is applied, move within the spherical socket formed by shells 10 and 19, the scope of movement being constrained by the fact of neck 26 having to extend through the cutaway portion 20.

By rotating the socket relative to the ball (it is easiest to think of the ball as - 6 fixed because it is on the top of the post or stalk 5 which is held firmly at its base), the tray 1 may be moved from lying in a vertical plane to lying in a horizontal plane. In this latter position, it may be supported directly by the lateral arm 32 extending from neck 26, to operate as a table. However, if it is desired to use the device shown in Figure 1 as a reading stand, then the tray 1 may be raised by with the head 25 moving inside the spherical socket formed by shells 10 and 19 until the neck 26 reaches the transverse portions of the T-shaped cutout 20 shown in Figure 2b and 3c. in this position, the configuration of the T-shaped cutout 20 now enables the tray to be swivelled to a degree from one side to the other, so as to align reading matter placed on the tray 1 in the most comfortable position for reading, e.g. particularly by a person on a sun lounger, or a beach towel, or on the sand, or the like, and who wishes to read a book whilst it is supported on the stand at a comfortable viewing angle.

Referring now to Figures 5 and 6, these show an alternative embodiment where the ball joint is set essentially underneath tray 1. Tray 1, the beverage container receiving apertures 6, spring clips 2 and vertical post 5 are essentially as in Figure 1 save that, for ease of manipulation of the spring clips 2, an extending tab 43 projects forward. By moving tab 43 to the right as shown in Figure 6, the end of clip 2 is raised away from tray 1 allowing easy insertion of the lower edge of a book, and turning of the papers is facilitated while keeping both open pages securely down when the book is being read.

As shown in Figures 5 and 6 of the drawings, however, connecting tray 1 with post 5 is somewhat differently configured from that in Figures 1 to 4. In Figures 5 and 6 the ball joint consists of a first component 40 and a second component made up of two moulded members 41 and 42 which may be clipped together via tabs 44 on member 41 engaging in slots 45 in member 42. - 7

The first component 40 has a head portion 45 configured analogously to the head 25 shown in Figures 4a and 4b. This is connected to a stalk 46 which is in turn connected to a prong 48 having relieving grooves 49. Prong 48 can be inserted into the top end of post 5, the insertion depth being limited by a collar 50. Head 45, stalk 46, collar 50 and prong 48 may be a single integral plastics moulding.

Stalk 46 passes through a cut-out 52 in the lower hemispherical shell member 41 and the shape of the cut-out 52 is such as to enable the tray 1 to be swivelled relative to post 5 clockwise as seen in Figure 6 from its horizontal position there depicted to a position in which tray 1 lies in a vertical or near vertical plane. This swivelling is carried out when the user wishes to erect tray 1, e.g. for use as a reading stand.

As can be seen in Figures 5 and 6, an integrally moulded wing 53 extends from the upper hemispherical shell 42 and is configured to support tray 1 when the tray is in the position shown in Figure 6. To assist stability when the tray 1 is in the position shown in Figure 5 and 6, the upper edge of wing 53 extends between two ribs 54 integrally moulded on the underside of tray 1. There are also two further strengthening ribs 56 moulded as part of tray 1.

As can be seen most clearly in Figure 6, the floor of tray 1 has a lowered portion generally indicated at 60. This lowered portion has a floor 61 having three slots 62 moulded in it. These slots 62 are designed to receive wedge shaped tabs 65 which are formed on a clipping portion of component 42 analogously to the way in which clip 3 fixes on the side wall of tray 1 as shown in Figures 1 and 2.

The upper portion of the clip fills the lowered portion of the floor of tray 1 to a certain extent so that there is only a small part of the upper surface of tray 1 is lower than the rest. - 8

Component 42 is moulded from a suitable resilient plastics material so that it may be clipped in and out of the lowered portion on the tray for assembly/disassembly of the tray table/reading stand as desired by the user.

Both of components 41 and 42 have a cut away section 71 and 72 respectively which allows the tray, when erected substantially vertically to act as a reading stand, to be additionally moved around the ball so that the lower edge of the tray member 1 may be inclined to the horizontal to left or right to suit the reading position of the reader. - 9 -

Claims

CLAIM$ 1. Ball joint consisting of a first component being an at least

part spherical ball portion having a connecting stalk attached thereto, and a second component in the form of a socket formed of two hemispherical shells having mutually engageable clip means allowing the two shells to be clipped together to define a hollow spherical cavity into which the part spherical ball portion of the first component may fit and wherein at least one of the shells has an aperture through which the connecting stalk may pass.
2. A ball joint according to Claim 1 wherein the relative sizes of the hollow spherical cavity and the part sphere or spherical section are such that when the two shells are clipped together, they form a tight fit around the spherical or part spherical ball portion of the first component, enabling the position of the ball to be adjusted relative to the second component simply by overcoming the frictional force between them.
3. A ball joint according to Claim 2 wherein the components are manufactured from resilient plastics material.
4. A ball joint according to Claim 1 wherein the components have formations which may inter-engage to hold the two components in a relatively fixed position.
5. A ball joint according to Claim 4 wherein the formations comprise a protrusion on one component and a dip on the other into which the protrusion may be engaged, but from which, by the application of a force sufficient to distort the components slightly, it may be released.
6. A ball joint according to Claim 4 wherein the formations comprise, on a part of the aperture in the form of a parallel-sided channel in which the stalk - 10 may slide, oppositely located pairs of low-profile bumps on the channel sides defining one or more specific positions for the stalk in the channel.
7. A ball joint according to any one of the preceding Claims wherein the two hemispherical shells of the second component, when clipped together, define a substantially T-shaped cutout enabling movement of the stalk to occur essentially up and down and, at one end of the up and down movement, from side to side, but not at the other end.
8. A ball joint according to Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.
9. A variable position stand comprising a support post and a supporting surface articulated thereto by means of a ball joint according to any one of the preceding Claims.