A CONNECTOR FOR THREE-DIMENSIONAL FRAME STRUCTURES

Abstract: A connector for connecting structural members such as panels (92,106), rods and tubes (80,234) to form a three-dimensional structure, comprises a connector body with a pair of axial slots (28,38) at opposite ends thereof shaped to receive and retain tongues (72,204) on the ends of the structural members and at least one annular channel (48,52,54) extending around the connector body to receive similar tongues of further structural members extending in directions transverse to those in the axial slots. The axial slots and channel have constrictions adjacent the outer surface of the connector body to retain tongues having widened free ends which are elongate in end view.

Description: This invention relates to a 3-dimensional structure comprising structural members such as elongate tubes or rods and/or panels. There has been a considerable increase in recent years in the use of spaceframes - three dimensional structures wherein elongate, and often flexible, rods or tubes are connected together by connecting members or 'nodes', and wherein each such connecting member may have several rods or tubes radiating from it in different directions. Panels can also be connected in this way. The components of such frames are usually made from lightweight materials such as plastics or aluminium. A particularly useful type of structure is the triangulated type from which a wide range of shapes such as domes and spheres can be made. Examples of known connectors are shown in EP-A-0 164 271, FR-A-2,059,876 and US-A-3,148,539. Connecting members which can connect a large number of structural members extending in three dimensions at a wide range of angles tend to be made up of a large number of parts, making them complicated to assemble. It is also necessary in many cases to take each connector apart in order to attach the structural members to it. US-A-3,476,421 discloses a spherical connector for frame-type structures which has several circumferential keyway channels formed around it at different angles. Alongside the keyway channels are narrow slots which allow the sidewalls of the channels to spread to receive the ends of snap-fitting struts, which are in turn held in place by locking elements inserted into the slots. The present invention aims to provide a system of structural members and connectors which is cheap to make and easy to assemble, and with which a wide range of structures can be made, connecting the structural members without the need to disassemble the connector. The present invention consists in a three-dimensional structure wherein a plurality of structural members are connected together by at least one connector comprising a connector body with a pair of axial slots at opposite ends thereof to receive and retain tongues on the ends of said structural members and at least one annular channel extending around the connector body to receive tongues of further structural members extending in directions transverse to those in the axial slots, the axial slots and the channel having constrictions adjacent the outer surface of the connector body, and a plurality of structural members each connected to said connector body by means of a projecting tongue having a widened free end, the tongue being inserted into one of the axial slots or channels of the connector and rotated through 90° to retain it therein by engagement with said constrictions (compare with FR-A-2059876), characterised in that the tongue connecting at least one of said structural members is formed at one end of an elongated joint of resilient material, the other end of the joint being retained in a threaded bushing which in turn is secured to an intermediate connector to which the respective structural member is attached. The connector used in the structure of the invention is preferably of essentially spherical shape, with slots at diametrically opposed positions and a circumferential channel extending around the connector body, midway between the two slots and symmetrical about a plane perpendicular to the diameter on which the two slots are aligned. The connector preferably also has two further annular channels, on either side of the first said channel, to accommodate further elongate members projecting at angles of about 45° relative to those projecting from the first said channel and from the diametrically opposed slots. In a preferred form the connector includes a core separable into two portions, the core comprising an essentially cylindrical portion having at each end a part-spherical portion, wider than the cylindrical portion, in which is formed one of the diametrically opposed slots. Three channels are defined by a pair of annular members surrounding the cylindrical part of the core, a main channel being defined between the two annular members and two secondary channels being defined between the partspherical core ends and respective adjacent annular members. The connector of the invention can be used for example to connect tubes which are slid into the intermediate cylindrical connectors. The tongues may be wedge shaped. Preferred embodiments of the present invention will now be described with reference to the accompanying drawings wherein: FIG. 1 shows, partly in elevation and partly in cross-section, a spherical connector for use in a threedimensional structure in accordance with the invention, showing how a tongue engages in the annular channel; FIG. 2 is a part sectional view, on the line II-II of the spherical connector of Figure 1; FIG. 3 is a cross-sectional view showing part of a modified spherical connector secured to an intermediate connector in a structure according to the invention; FIG. 4 shows an end-on view of the parts of a connecting tongue assembly for use in the structure of the present invention; FIG. 5 is an axial cross-sectional view of the parts of the assembly of Figure 4; FIG. 6 is a part-sectional view of a panel connector for use in conjunction with the assembly of Figures 4 and 5; FIG. 7 shows schematically how several different structural members can be connected together using the connector of Figure 1; FIGS. 8 and 9 show examples of the kind of structure which can be made using the connectors of the invention; and FIG. 10 shows a connecting member in the form of a lamp support for use with the 3-dimensional structure of the invention. Referring first to Figures 1 and 2, a spherical connector is made up of two core members 10, 12 threadedly connected together and two identical annular members 14, 16 surrounding the core formed by members 10, 12. These components are suitably made from plastics material, and their shape is such that they can easily be made by injection moulding. Alternatively, for a stronger system, they could be spun from aluminium. The core member 10 comprises a hollow cylindrical shank 18 having an outer threaded portion 20 at one end. The other end has integrally-moulded longitudinal spacing bars 22, the ends 24 of which retain the annular member 14 in position. On the end of the shank remote from the threaded portion is a part-spherical head 26 forming part of the spherical surface of the connector. An elongate rectangular slot 28 is formed in the head 26 to receive a tongue of an intermediate connector or structural member as will be described below. The slot 28 communicates with the hollow interior of the shank, and a tapering inner surface 30 extends from the slot 28 to the cylindrical inner wall of the shank, forming a bearing surface against which a connector tongue 66 abuts. The core member 12 has a cylindrical hollow shank 32 which is shorter than shank 18 and has an inner screw thread by means of which the two core members are screwed together to form a symmetrical core. The axial end 34 of the shank 32 forms an abutting surface facing the axial ends 24 of spacing bars 22. The core member 12 also has a part spherical head 36 with a slot 38, identical to those on the core member 10, so that structural elements of a spaceframe can be connected to opposite ends of the core. Surrounding the core are the annular members 14,16, which are held against axial movement between the spacing bars 22 and the end of the shank 32. Each of these annular members comprises a cylindrical inner portion 40 which fits around the cylindrical shank 18, an annular flange 42 extending radially outwardly from one end of the inner portion 40 and an outer portion 44 having a part-spherical outer surface, a frusto-conical inner surface 43 and a cylindrical or slightly flared inner surface 46. The inner surfaces 43 define between them part of a circumferential channel 48 which can accommodate tongues 72 of several spaceframe elements, extending radially outwardly at right angles to those accommodated in slots 28,38. Serrations 45 as shown in Figure 2 may be formed on the surfaces 43, to assist secure location of the tongues 72, by engaging corresponding ridges on the tongue. The opposed outer edges of this channel are defined by flat annular surfaces 50 on each of elements 14,16, between the inner surface 43 and the part-spherical outer surface. The annular members are preferably held against rotation around the core by longitudinal keys 47 (Figure 2) on the core engaging in corresponding slots in the inner surfaces of the annular members. Two further annular channels 52,54 are defined between the heads 26,36 of the core members and the respective adjacent annular members 14,16. These channels can accommodate further spaceframe members extending at angles of about 45° to those held in the channel 48 or slots 28, 38. The outer edges of these channels are defined by opposed frusto-conical surfaces 56, 58. The surfaces against which the tongues will abut are the inner surface 46 of the annular member and the underside 60 of the core head 26 or 36, which surfaces may also be serrated like the surfaces 43. The connector is assembled by sliding the two annular members 14, 16 onto the cylindrical shank 18 of the core member 10 and screwing the other core member 12 onto the threaded portion 20 of the shank 18. An intermediate connector 62 is shown in Figure 1 with a tube 80 attached to it. These connectors are essentially cylindrical and may suitably be made from aluminium or injection-moulded plastics. A unitary joint 66 made of hard rubber or other resilient material is used to connect an intermediate connector (not shown in Fig. 1) to the spherical connector. This joint is elongate and has at one end a tongue 72 which is in the form of a wedge-shaped prism. Being of elongate configuration, the tongue can be inserted into any of channels 48, 52, 54 and retained there by rotating it through 90° so that it engages the inner surfaces such as 43. An elongate frame member in the form of a tube 80 is fitted over the left hand cylindrical connector, as shown in Figure 1, integral projections 82 providing a friction fit to retain the tube in position, and the end of the tube abuts an annular flange 84 surrounding the cylindrical connector. Apertures may be provided in the walls of the cylindrical connectors to enable the tubes 20 to be used as wiring conduits. Tubes of different diameter can be connected using the connector of Figure 1, simply by using intermediate connectors whose cylindrical parts are of different diameter but which have the same tongue and joint arrangement. An example of such a connector is shown in Figure 3 and will be described in more detail below. The hard rubber connectors 66 are under slight tension in the assembled space frame, so that the entire structure is under slight inward tension, increasing its rigidity and stability. Figures 4 and 5 show, in end view and in axial cross-section respectively, a tongue connector assembly for use in the structure of the invention. This includes a rigid connector 200 which is similar to the connectors 66 except that its tongue portion 204 has rounded surfaces 205 to match corresponding abutment surfaces in a modified spherical connector which will be described below. Like the connector 66, the connector 200 has an elongate connecting portion 208. At its end remote from the tongue it has a cross-shaped retaining portion 206. The next part of the assembly is a spacer member 201, suitably of hard rubber, to provide a degree of resilience which is annular in shape with a central opening 209 having four radial recesses 210 so that its shape matches the cross-shaped retaining portion 206 of the connector 200, which can pass through it. One side surface 212 of the spacer is part spherical in shape, to match the outer surface of a spherical connector. The opposite side has a shallow recess 211, to accommodate one end of the next part of the assembly which is a bushing 202. This has a widened end 214 fitting into the recess 211 and a threaded portion 216 to enable the whole assembly to be screwed into a structural member or a further connector to which the structural member can be attached. The bushing 202 has an axial passage 215 therethrough, the cross section of this passage being identical with that of the spacer 201 to enable the end 206 of the tongue connector 200 to pass through it. The last member of the assembly is a part-annular collar 203 having on one side a recess 219 which is circular in outline and surrounds a central circular part of an opening 218. This collar fits over the connector 200 to retain it in the bushing 202, the central part of the opening 218 fitting over the elongate central part 208 of the connector and the retaining portion 206 abutting the recessed portion 219 of the collar. Figure 6 shows one type of intermediate connector into which the assembly of figures 4 and 5 may fit. This connector includes a flat bar 220 with an aperture 224 to accommodate a screw connector or the like to connect a panel to the bar. At one end of the bar is a connecting portion 221 with a threaded bore 222 into which may be screwed the bushing 202 through which is inserted the tongue connector 200. The retaining portion 206 of the tongue connector together with the collar 203, will be received in a recess 223 at the inner end of the threaded bore 222. Figure 3 shows how the assembly of figures 4 and 5 can be used to connect a modified spherical connector 226 to an intermediate connector 225 to which can be connected in turn, for example, a tubular structural member 234. The spherical connector is similar to that shown in Figure 1 except that the abutment surfaces 227 are of arcuate cross-section rather than flat. They thus match the arcuate surfaces 205 of the retaining tongue 204 of the connector 200. As has been briefly described above, the elongate central portion 208 of the connector 200 passes through the annular spacer 201, the bushing 202 and the retaining collar 203. The intermediate connector 225 is then screwed on to the assembly, the threaded portion 216 of the bushing being received into a correspondingly threaded axial bore at one end of the connector 225. The connector 225 is shown accommodating a tubular structural member 234 of relatively large diameter, this fitting over a wide cylindrical portion 230 of the connector 225, the end of the tube being spaced from an annular shoulder 239 of the connector 225 by a rubber washer 235. From the widened cylindrical part 230 the connector tapers at 227 inwardly towards the bore which receives the bushing 202. Coaxially within the wide cylindrical part 230 of the intermediate connector 225 is a second cylindrical part 228 of small diameter which has, at the end opposite to the bushing 202, a threaded axial bore 232 into which another structural member such as a rod may be screwed. It will be appreciated that a wide variety of different types of intermediate connector can be secured to the spherical connector 226 with the assembly shown, to accommodate different sizes and shapes of structural members. In the assembly shown in Figure 10, two parts of a spherical connector such as that shown in Figure 3, namely a core member 241 and an annular member 242, are screwed into a cylindrical support 243 which has a central threaded bore 250. Two annular channels 251, 252 are thus defined which can be used to accommodate structural members as already described above. Into the opposite end of the threaded bore 250 is screwed a base 244, with a screw threaded central shank 253, to which is secured a bracket 245 holding a spotlamp 246. This assembly can thus be secured at any convenient part of the three-dimensional structure being connected to other structural members in the same way as the spherical connectors of the invention. Wiring for the lamp can pass through an aperture in the bracket 245, through the bore 250 and through the central bore of the core member 241 before passing out through the axial slot of the core member. Thereafter it can if desired pass through an aperture such as 67 in an intermediate connector and along a tube connected to it. It will be appreciated that various other structural members and accessories can be incorporated into a structure formed in accordance with the invention. For example, in place of the support bracket for a spotlamp, a flat base could be secured to the underside of the cylindrical support 243 and used either to support the structure on the floor or to be secured to the floor or ceiling. Figure 7 shows how three tubes and three panels can be connected to a single spherical connector 100. Tubes 80, 103 and 105 of different diameter are connected by respective cylindrical connectors 62, 102 and 104, as described in connection with Figures 1 to 4, serrations 45 in the channel 48 helping to retain the tubes in the relative angular disposition shown. Also connected to the spherical connector are a panel 92 connected by an integrally moulded joint 66 as in Figure 5 and two panels 106, one coplanar with the panel 92 and one at right angles to it. The two panels 106 are secured by brackets 108 which are themselves secured in the channel 48 by means of tongues, in the same way as the other connectors. The panels are secured in the brackets by bolts 110. Tubes which are connected using the connectors of the invention are not confined to a rigid configuration but have a degree of play allowed by the resilience of the hard rubber joints 66 or 208. Furthermore, because the channels 48, 52, 54 are continuous, tubes can be supported by these channels at any desired angle relative to one another. Indicia such as 88 are provided on the surface of the spherical connector to assist in the positioning of the tubes. Figures 8 and 9 illustrate typical triangulated structures which can be constructed from tubes 80 and connectors 90 according to the invention. Such structures can be put together without dismantling any spherical connectors, simply by sliding the intermediate connector into the end of each tube, inserting the tongue 72 into one of the channels 48, 52, 54 or slots 28, 38 and rotating the tube through 90° about its longitudinal axis to secure the connection. Similar structures can be made to include panels.

Claims: A three-dimensional structure wherein a plurality of structural members are connected together by at least one connector comprising: a connector body with a pair of axial slots (28, 38) at opposite ends thereof to receive and retain tongues (72, 204) on the ends of said structural members and at least one annular channel (48) extending around the connector body to receive tongues of further structural members extending in directions transverse to those in the axial slots, the axial slots and the channel having constrictions adjacent the outer surface of the connector body, and a plurality of structural members (80) each connected to said connector body by means of a projecting tongue (72, 204) having a widened free end, the tongue being inserted into one of the axial slots or channels of the connector and rotated through 90° to retain it therein by engagement with said constrictions, characterised in that the tongue (204) connecting at least one of said structural members is formed at one end of an elongated joint (200) of resilient material, the other end of the joint being retained in a threaded bushing (202) which in turn is secured to an intermediate connector (225) to which the respective structural member is attached. A three-dimensional structure according to claim 1 characterised in that the connector body is of substantially spherical shape, with slots (28, 38) at diametrically opposed positions and a circumferential channel (48) extending around the connector body, midway between the two slots and symmetrical about a plane perpendicular to the diameter on which the two slots are aligned. A three-dimensional structure according to claim 2 characterised in that the connector body has a further annular channel (52, 54) on each side of the first said channel to accommodate further elongate members projecting at angles of approximately 45° relative to those projecting from the first said channel and from the diametrically opposed slots. A three-dimensional structure according to any preceding claim characterised in that the connector body comprises a core separable into two portions (10, 12), the core comprising a substantially cylindrical portion (18) having at each end a part-spherical portion (26, 36) wider than the cylindrical portion, in which is formed one of said diametrically opposed slots. A three-dimensional structure according to claim 4, characterised in that three annular channels (48, 52, 54 are confined by a pair of annular members (14, 16) surrounding the cylindrical part (18) of the core, a main channel (48) being defined between said annular members and two secondary channels (52, 54) being defined between said part-spherical core ends (26, 36) and respective adjacent annular members (14, 16). A three-dimensional structure according to any preceding claim characterised in that a tubular structural member (80, 234) is fitted over one said intermediate connector. A three-dimensional structure according to any preceding claim characterised in that a panel (106) is secured to one said intermediate connector (108).

Inventors: RADCLYFFE, SIMON PETER
Applicants: RADCLYFFE, SIMON PETER
Application year: 1987
Main classification: E04B1
IPC codes: E04B1