GB2156029A - Framework of changeable shape - Google Patents

Abstract

Rods 12 extend between connectors 14 at respective nodes of the framework 10. A motor driven rack-and-pinion mechanism in each connector 14 constrain the rods 12 to move in synchronism when the shape of the framework 10 is changed so that the shape changes uniformly from elongate to that in which it forms multiple sub-frames 26 each defining the outline of a hexahedron. The framework functions as an antenna, or as a support for eg solar panels or cargo for terrestial or space use. <IMAGE>

Description

SPECIFICATION Framework of changeable shape The invention relates to frameworks of changeable shape.

Frameworks have many uses but the invention is concerned particularly with frameworks made up of members which are pivotally inter-connected so as to enable the shape of the framework to be changed from a first shape which, for example, may facilitate transportation or storage to a second, working, shape, for example.

According to the invention a framework of changeable shape comprises at each node a connector and elongate members each of which extends between and is pivotally connected to two connectors, the connection at each connector being about a respective pivot axis at 120 to the axis about which each adjacent member is pivotally connected to the connector, the pivotal axes of the connector being parallel to a common plane and the separations of the respective pivotal axes of the members being equal, and each connector comprising rack-and-pinion mechanism by which the members connected to the connector are constrained to turn about their respective pivot axes in synchronism as the shape of the framework changes.

In preferred constructions of framework according to the invention the framework can be changed from a shape in which it forms multiple-sub-frames each defining the outline of a hexadedron to a generally flat shape; or from a generally elongate shape in which the elongate members extend generally parallel to the longitudinal direction of the framework to a shape in which it forms multiple sub-frames as aforesaid.

One form of framework will now be described by way of example to illustrate the invention with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic isometric view of the framework arranged to form multiple sub-frames each defining the outline of a hexahedron; Figure 2 is a diagrammatic side view of the framework arranged in an elongate shape; Figure 3 is a diagrammatic isometric view of the framework arranged in a generally flat shape; Figure 4 is an isometric view of rack-andpinion mechanism forming part of a connector used in the framework; Figure 5 is an isometric view of pinions used in the mechanism shown in Fig. 4.

Figure 6 is a diagrammatic enlarged plan of one of the connectors in its configuration shown in Fig. 3, a part being omitted to reveal the internal construction; and Figure 7 is a diagrammatic section on the line VII-VII in Fig. 6, some parts being omitted for clarity.

The framework 10 shown in the drawings consists of thirty-six elongate members 12, each extending between two of the connectors indicated at 14, 60, 62, 64, 66, 68, 70, 72 and 74 in Fig. 1 at respective nodes of the framework 1 0. Each member 1 2 is a rod, beam, girder or other member and is connected at its ends to respective sockets 1 6 (Fig. 4). The sockets 1 6 are each integral with a respective toothed pinion 1 8 forming part of rack-and-pinion mechanism (Fig. 4) described below. There is a connector assembly 20 in each connector of the framework 10 and each assembly 20 contains a respective rack-andpinion mechanism.When the framework 10 is arranged in the shape as shown in Fig. 1, it forms multiple sub-frames such as 26, for example, each defining the outline of a hexahedron. The form of each hexahedron depends on the shape to which the framework 10 is adjusted. As shown in Fig. 1, each hexahedron is cubic.

The connector assembly 20 in each case includes an outer housing (described below) in which there are bearings rotatably supporting the two journals 24 of six (or less) pin ions 1 8.

The journals 24 define pivotal connection axes for the respective members 1 2 connected to the connector.

The rack-and-pinion mechanism is such that, if three alternate sockets 1 6 pivot in one sense, the three other alternate sockets 1 6 pivot in the opposite sense.

This action is effected by inter-connections between the pinions 1 8. The inter-connections consist of six similar toothed racks 30 and pinions 36 and 38 arranged between the racks 30. Each rack has an outer face 32 bearing teeth (not shown) meshing with a respective pinion 18. The racks 30 are in a regular hexagonal array and each has an inner face 34 bearing teeth (not shown) meshing with two pinions 36. The racks 30 opposite one another in the hexagonal array are interconnected by two elongate pinions 38 meshing with the respective pinions 36 at either side. Each rack is guided in its longitudinal movement by matching internal surfaces in the housing (not shown). The housing also engages the ends of the pinions 38 which are thus prevented from moving endwise. All pinins are fully floating.

The pinions 36 are shown only diagrammatically. Each pinion is prevented from moving sideways for example by a spider (not shown) which slides within the housing. Alternatively, the pinions 36 are replaced by longer pinions as indicated in ghost outlines at 37 in Fig. 6.

Endwise movements of the pinions 37 are restricted or prevented by the engagement of the ends of the pin ions 36 with the respective adjacent racks 30 between which the pin ions 37 extend.

The pinions 38 extend between two other racks 30 at either end and mesh with teeth (not shown) on the side-faces 40 of those other racks 30. The side-faces 40 of each rack 30 are mutually inclined so that the rack 30 tapers in the direction towards the centre of the hexagonal array.

It is clear from Fig. 4 that if three alternate sockets 1 6 pivot in one sense about their axes defined by the journals 24, the other three sockets 16 must pivot in the opposite sense in synchronism. The positions of the sockets 1 6 shown in Fig. 4 correspond to the elongate shape of the framework shown in Fig. 2.

Fig. 5 shows all the pinions 36 and 38 but omits the racks 30 and sockets 1 6.

Figs. 6 and 7 show the housing at 50. It has a generally spherical external surface and has three pairs of mutually opposed plain internal faces at 52 which are engagable by the respective ends of the pinions 38. The faces 52 alternate with plain faces 54 guiding respective racks 30. The positions of the sockets 1 6 shown in Fig. 6 correspond to the positions of the sockets 16 and the racks 30 shown in full lines in Fig. 7 and correspond to the flat shape of the framework 10 shown in Fig. 3. The positions of the sockets 1 6 shown in ghost outlines in Fig. 7 correspond to the elongate shape of the framework 10 shown in Fig. 2. The corresponding positions of the racks 30 are shown in ghost outlines in Fig.

7.

Three alternate sockets 1 6 are pivotable about respective axes which are defined by the respective journals 24 and which lie in a common plane 56 (Fig. 7). The remaining three sockets 1 6 are pivotable about respective axes which lie in another common plane 58 (Fig. 7) parallel to, but offset from, the plane 56. The offset between the planes 56 and 58 is clearly shown in Fig. 4 (the planes themselves not being shown) and facilitates the close approach of the four pairs of overlying connector 60, 62; 64, 66; 68, 70; and 72, 74 in the flat shape of the framework 10 (Fig. 3).

The pivotal axes of the sockets 1 6 in each connector when seen as shown in Fig. 6 are mutually positioned as the sides of a regular hexagon, adjacent axes being mutually inclined at 120 , and in Fig. 2 the positions of the axes of the pivotal connections between the connectors and the members 1 2 are schematically represented on a hexagon in each connector.

The rack-and-opinion mechanism in the connectors at the nodes of the framework 10 ensure that the members 1 2 move in synchronism so that the shape of the framework 10 can change uniformly from the flat shape shown in Fig. 3 to the shape shown in Fig. 1 and then to the generally elongate shape shown in Fig. 2 in which the members 12 all extend generally parallel to the lengthwise direction of the framework shape. Only relatively slight longitudinal movement of the racks 30 is necessary to cause the complete change from the Fig. 3 shape to the Fig. 2 shape.

The rack-and-pinion mechanisms ensure that as the shape of the framework is changed, the relative movement between the elongate members is the same at each connector and the change of shape of the framework is uniform throughout.

In the flat shape of the framework 10 shown in Fig. 3, the sockets 16 in each connector extend in six equiangularly separated directions, as already mentioned above.

Connectors to which less than six members 1 2 are connected are constructed the same as the connector described above but have one or more unoccupied sockets 1 6.

If necessary, the connectors can be provided with frictional resistance or locking devices to hold the framework 10 in a shape in which it has been arranged.

The shape of the framework 10 can be changed by motors in the connectors arranged to drive the rack-and-pinion mechanisms 20, the motors being omitted from the drawings.

The framework 10 is not limited to the number of elongate members and connectors described above but may comprise any number arrangeable to form sub-frames, in any number, each of hexahedron outline.

The framework described above with reference to the drawings, or modified as explained, has many uses. For example, it may be used as a collapsible radio or radar antenna for terrestrial or space use; or as a general-purpose support for other structures, for example solar panels or cargo.

The shape shown in Fig. 2 facilitates storage or transportation of the framework. Either of the shapes shown in Figs. 1 and 3 may be used as the working shape, or the working shape may be a shape displaced from those shapes.

In some uses of the invention the framework may be constructed so as to be changeable to adopt a range of shapes less than the full range described with reference to the drawings. For example, so as to change from the Fig. 2 shape to only one of the shapes shown in Figs. 1 and 3.

The working effect of the framework may be derived by the action of changing the shape of the framework for example cyclically.

The framework in modifications (not shown) comprises fewer or more sub-frames than the four shown in the drawings.

The framework can be supported on a surface such as a platform or deck or on the ground in a variety of positions. The shape of the framework can be changed by the operation of motors in the connectors as already mentioned or by other means acting on some of the connectors or on some of the members 1 2. As the shape changes the connectors engaging the supporting surface or some of them move over the surface for example by sliding; or those connectors can bep provided wheels or rollers for example to facilitate such movement.

Claims (8)

1. A framework comprising at each node a connector and elongate members each of which extends between and is pivotally con nected to two connectors, the connection at each connector being about a respective pivot axis at 120 to the axis about which each adjacent member is pivotally connected to the connector, the pivotal axes of the connectors being parallel to a common plane and the separations of the respective pivotal axes of the members being equal, and each connector comprising rack-and-pinion mechanism by which the members connected to the connector are constrained to turn about their respective pivot axes in synchronism as the shape of the framework changes.

2. A framework according to Claim 1, in which the rack-and-pinion mechanism comprises for each elongate member a respective first pinion rotatable with the member, a hexagonal array of parallel spaced apart racks engaging respective ones of the first pinions at surfaces facing outwardly of the array, and three pairs of elongate pinions, each pair engaging side surfaces of two adjacent racks at one side of the array and of two adjacent racks at the opposite side of the array, each elongate pinion being engaged at opposite sides by respective intermediate pinions which engage inwardly-facing surfaces of racks at opposite sides of the array, and the first pinions being rotatably mounted in a housing in which the racks are longitudinally movable.

3. A framework according to Claim 2, in which movements of each intermediate pinion in the direction of its axis of rotation is limited by engagements between the ends of the pinion and the racks between which it extends.

4. A framework according to any preceding Claim, in which each connector has six first pinions, the pivotal axes of three alternate first pinions lying in a common plane which is parallel to and offset from a plane in which the pivotal axes of the other three first pinion lie.

5. A framework according to any preceding Claim, in which each connector comprises a hollow housing to which the members are pivotally connected each about a respective one of the pivotal axes, the housing accommodating the elongate and inetermediate pinions and the racks.

6. A framework according to any preceding Claim, which can be changed from a shape in which it forms multiple sub-frames each defining the outline of a hexahedron to a generally flat shape.

7. A framework according to any preceding Claim, which can be arranged in an elongate shape in which the elongate members extend generally parallel to the longitudinal direction of the framework and can be changed in shape to form multiple sub-frames each defining the outline of a hexahedron.

8. A framework substantially as herein described with reference to Figs. 1 to 7 of the accompanying drawings.