JOINTS FOR MODULAR SUPPORT STRUCTURES

Abstract: A joint for a modular support structure, comprising a plurality of connector arms at least one of which is provided with a plurality of differently sized mating surfaces (4a, 4b, 4c) to enable the joint to mate with one of a number of different supports.

Description: JOINTS FOR MODULAR SUPPORT STRUCTURES This invention relates to a joint for use with modular support structures in particular tent frames and scaffolding. It is known to use a plurality of supports of different sizes, i.e. of different cross- sections, such as tent or scaffolding poles, in conjunction with a plurality of joints of corresponding sizes to construct a modular support structure. The size of the modular support structure to be constructed determines the cross- section of the supports required. For larger structures, such as marquees, large diameter poles are required to withstand the large compression and bending forces experienced in the vertical supports whilst smaller diameter poles can be used in other __ areas, such as horizontal supports, where there are lower compression and bending forces, to minimise weight. Where the structure is smaller, for instance a small tent, the supports used will also be smaller due to the lower weight, and therefore lower compression and bending forces, the structure is required to support but may still be of differing diameters to save weight. The use of different size poles in a single structure requires the use of a large number of different joints. Moreover these joints are often designed specifically for a particular structure. As the complexity of the structure increases so does the number of different joints and therefore the difficulty of assembly of the structure, particularly in adverse climatic conditions or in the dark. As a result of the need for a large variety of joints for each structure and because differently sized structures require a different variety of joints there is a need to carry a large number of different spare parts where a number of different structures are required. This not only increases production costs but also increases spares costs and stocks required. According to the present invention there is provided a joint for a modular support structure comprising a plurality of connector arms characterised in that at least one connector arm is provided with a plurality of different sized mating surfaces, so as to . enable the connector arm to mate with any one support selected from a group of different sized supports. The existence of the different sized matins surfaces on the connector arm means one connector arm can mate with a large number of different supports and as such fewer different joints are needed, despite the use of supports of different sizes, to form a modular support structure. This can lead to reduced manufacturing costs and gives much improved commonality of parts for structures of different sizes and means that a kit for a specific structure can be assembled from a store of a few different joints and number of standard supports. Thus where a number of different structures are required fewer spare parts are required overall. Also the complexity of assembling the structure is reduced. In practice it is usual for supports to be of a substantially circular cross-section as such the connector can be arranged so that at least one of the connector arm mating surfaces is of substantially circular cross-section. This allows existing supports to mate with joints according to the present invention and also allows for ease of manufacture. A plurality of differently sized mating surfaces can be formed on the at least one connector arm co-axially or in an eccentric arrangement. Particularly preferred is the co-axial arrangement which allows for ease of manufacture and a consistency of jointing direction. The at least one connector arm may be arranged so as to be able to mate with a surface on each of the variety of supports to be used with the joint. The mating can be achieved by any suitable means such as the use of a 'male connector arm' or a 'female connector arm' or a connector arm which can act as both a 'male' or a 'female' connector arm. In use as a 'male connector arm' the at least one connector arm can be configured so as to have a plurality of differently sized mating surfaces arranged co-axially or in an eccentric arrangement on the connector arm. Such a configuration allows the inside surface of a support to mate with a corresponding surface on the outside of the connector arm. In use as a 'female connector arm' the at least one connector arm can be configured so as to be hollow. In such a configuration a mating surface, or a plurality of differently sized mating surfaces arranged co-axially or in an eccentric arrangement, can be located on the inside of the connector arm. Such a configuration allows the outside surface of a support to mate with a corresponding surface on the inside of the connector arm. In use as a 'male or a female connector arm' the at least one connector arm can be configured so as to have at least one mating surface on the outside of the connector arm and also to be hollow so as to provide at least one mating surface on the inside of the connector arm. Such a configuration allows a support to mate either with a mating surface on the outside or inside of the connector arm. This configuration therefore allows for a larger number of differently sized mating surfaces to be arranged on a single ™nnector arm than when the connector arm is configured solely as a 'male' connector arm or a 'female' connector arm. In order to increase the friction between the mating surface on the connector arm and the mating surface on the support whilst they are in contact with each other, and therefore the strength of the joint, a mating ring of suitable material such as rubber can be provided on or abutting either of the mating surfaces. Alternatively mating rings can be provided on or abutting both the connector arm and the support mating surfaces. The or each mating ring should be of suitable dimensions so as to project slightly above the mating surface which it is on or abuts whilst still allowing the mating surfaces to mate. Advantageously the or each mating ring could be located in a groove formed in either or both of the mating surfaces. The mating ring could be adapted so that a connector arm or a support only requires a single mating ring to be used covering all mating surfaces or individual mating rings could be used for each mating surface. Advantageously a joint according to the present invention can be arranged so as to have bores in or around the hub of the joint. The bores can be used both to reduce the overall weight of the joint and also to provide points at which items can be connected to or suspended from the joint. Usefully the present invention can result in there being a requirement for only two different configurations of joint in a typical kit; a 'T' shaped joint having three connector arms with their longitudinal axis in the same plane, which allows connections at right angles to each other, and a '+' shaped joint having four connector arms three of which have their longitudinal axis in the same plane with the fourth connector arm having its longitudinal axis at an angle to this plane. The '+' shaped arrangement allows one of the supports to be mounted at an angle other than 90° to the other supports forming, for example, a pitched roof for a tent. As a result of the use of joints according to the present invention, a single kit need only contain a plurality of the 'T' and '+' shaped joints and a plurality of supports of different dimensions to assemble a variety of different support structures. By way of example only a kit containing the following components can produce three different tent structures; a large structure 5.5m x 7.3m; a medium structure 3.7m x 3.7m or a small structure 2.7m x 2.7m: i/ 10 'T' shaped joints sized to receive 30mm and 50mm diameter poles ii/ 25 '+' shaped joints sized to receive 30mm and 50mm diameter poles iii/ 12 poles 30mm in diameter and 800mm in length iv/ 10 poles 50mm in diameter and 1100mm in length v/ 20 poles 30mm in diameter and 1100mm in length vi/ 20 poles 50mm in diameter and 1700mm in length vii/ 28 poles 30mm in diameter and 1700mm in length An embodiment of the invention will now be described, by way of example only, with reference to the drawings, in which: Figure 1 is a plan view of a joint in accordance with the invention; Figure 2 is a side elevation view of the joint shown in figure 1 ; Figure 3 is a side elevation view, at 90° to the elevation shown in figure 2, of the joint shown in figure 1 ; Figure 4 is a cross-section of figure 3; Figure 5 is a cross-section of figure 3 showing an alternative internal embodiment. A joint in accordance with the invention comprises a plurality of connector arms, la to Id, each having a plurality of different sized mating surfaces, 2a and 2b, to allow each connector arm, la to Id, to mate with any one support selected from a group of different sized supports, one of the different sized mating surfaces, 2a or 2b, corresponding to one of the mating surfaces of one of the supports. Each connector arm, la to Id, forms an integral portion of the joint which extends outwardly from the hub of the joint, 3. Figure 5 illustrates an alternative embodiment wherein at least one of the connector arms, la to Id, has three different sized mating surfaces, 4a to 4c. The joint shown in figure 1 incorporates a central bore, 5, and radial bores, 6a to 6d, which allow the user to attach items to, or suspend items from, the joint, such as inner liners in tents. The joint also shows, near the outer lip of each of the connector arms, la to Id, a groove, 7a to 7d, formed about the diameter of the connector arm which is adapted to receive an 'O' mating ring of suitable material such as rubber. This 'O' ring, when fitted in the groove of the connector arm, acts to increase the friction between the mating surfaces of the connector arm and the support mating with the connector arm, thus increasing the strength of the joint.

Claims: CLAIMS 1. A joint for a modular support structure comprising a plurality of connector arms characterised in that at least one connector arm is provided with a plurality of different sized mating surfaces so as to enable the connector arm to mate with any one support selected from a group of different sized supports. 2. A joint according to claim 1 wherein at least one of the cormector arm mating surfaces is of substantially circular cross-section. 3. A joint according to claims 1 or 2 characterised in that the connector arm mating surfaces comprise a co-axial arrangement of differently sized surfaces. 4. A joint according to any of the preceding claims wherein at least one of the connector arms is a female connector. 5. A joint according to any of the preceding claims wherein at least one of the connector arms is a male connector. 6. A joint according to any of the preceding claims wherein at least one of the connector arms is both a male and a female connector. 7. A joint according to any of the preceding claims comprising at least four connector arms wherein one of the connector arms has its longitudinal axis orientated at an angle to the plane of the longitudinal axis of the other three connector arms. 8. A joint according to any of claims 1 to 6 comprising three connector arms wherein the connector arms have their longitudinal axis in the same plane. 9. A joint according to any of the preceding claims wherein a mating ring is provided on or abuts at least one of the connector arm mating surfaces. 10. A kit for a modular support structure comprising a plurality of joints according to any of the proceeding claims and a plurality of supports. 11. A joint substantially as herein described with reference to Figures 1,2,3 and Figure 4 or 5.

Inventors: DAVIES GARETH, DAVIES, GARETH
Applicants: DAVIES GARETH, SECR DEFENCE, DAVIES, GARETH, THE SECRETARY OF STATE FOR DEFENCE
Application year: 1998
Main classification: E04H15
IPC codes: E04B1, E04H15