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Machine translation
1. (WO1992022102) FOLDABLE STRUCTURES
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

FOLDABLE STRUCTURES

The invention relates to foldable structures. The invention has many applications, but is basically concerned with a structure which takes up very little space when folded, but can then be expanded to cover a large area or occupy a large space. One particularly important use is to provide a structure in space, for example for use as a satellite dish or space platform. Other uses will be referred to later.

The invention provides a foldable structure comprising a plurality of first nodes and a plurality of opposed second nodes, the nodes being interconnected by links pivotally attached thereto, the arrangement being such that in a folded condition the first nodes are grouped together, and the second nodes are grouped together spaced from the first nodes, but on relative movement of the first nodes towards the second nodes, the links cause the first nodes to expand outwardly from one another, and also cause the second nodes to expand outwardly from one another, substantially increasing the size of the structure, the structure also including means to limit the movement of the first nodes towards the second nodes.

Preferably, the limiting means comprises tension means connected between the first nodes and/or tension means connected between the second nodes.

The tension means may comprise cords, cables or like tension members which collapse when the nodes are moved back towards the folded condition.

Alternatively or in addition, the tension means may comprise a flexible sheet member, for example to provide a skin for the structure in the expanded condition.

Means may be provided to lock the nodes together when the first nodes have reached the limit of their relative movement towards the second nodes.

The locking means may comprise tie members extending from the first nodes to the second nodes.

Each first node may be paired with an opposed second node, the nodes being mounted on a common tie member along which relative sliding movement can take place as the nodes move between their folded and expanded conditions.

Means may be provided to lock the node members in position on the tie member.

The nodes may be resiliently biased into certain positions.

Each node may have a plurality of pivot axes for the links, the axes being arranged to form the sides of a regular polygon.

Each first node may be pivotally connected by the links to each of the second nodes which is adjacent to the second node opposite to the said first node.

By way of example, specific embodiments of the invention will now be described, with reference to the accompanying drawings, in which :- Figure 1 is a plan view of a component of a foldable structure according to one embodiment of the invention, one top node being omitted for clarity;

Figure 2 is a view on line II-II of Figure 1;

Figure 3 is a view on line III-III of Figure 1, but showing an alternative embodiment;

Figure 4 is a perspective view of the component of Figure 1;

Figure 5 is a detailed view of one node;

Figure 6 is a plan view of the component in the folded condition;

Figure 7 is a view on line VII- VII of Figure 6;

Figure 8 is a view on line VIII- VIII of Figure 6;

Figure 9 is a perspective view of the component in the folded condition; and

Figure 10 is a diagrammatic view of an entire structure according to an embodiment of the invention.

The drawings show a node and link module which can be assembled with similar modules to provide a foldable structure of any desired size. One such structure is shown in Figure 10 and will be described in detail later.

Firstly, a single module will be described in detail.

The module has four upper nodes la, lb, lc and Id and four lower nodes 2a, 2b, 2c and 2d. To assist in differentiating between the two sets of nodes, the upper nodes 1 are shown shaded. Upper node Id has been omitted from Figure 1 for clarity. The complete module is perhaps best shown in the perspective view, Figure 4.

The node Id is pivotally connected by links 3 to each of the lower nodes which is adjacent to the lower node 2d lying opposite to node Id.

Node 2d is similarly connected by pivotal links 3 to each of the upper nodes surrounding node Id, i.e. nodes la, lb and lc. The structure thus presents a double tripod of considerable strength.

In a large structure such as that shown in Figure 10, each of the upper nodes will be similarly connected to lower nodes, and each of the lower nodes will be similarly connected to upper nodes.

The effect of the pivotal link connections is that the structure can be freely moved between the expanded condition shown in Figures 1 to 4 and the folded condition shown in Figures 6 to 9. In the folded condition, the upper nodes 1 are grouped together and the lower nodes 2 are grouped together, the two groups being spaced apart by a distance which is almost equal to the length of the links 3.

The structure can be moved from the folded condition to the expanded condition by moving the nodes 1 towards the nodes 2. As the nodes 1 move towards the nodes 2, the compressive force supplied by the links 3 forces the nodes 1 and the nodes 2 to spread out to the positions shown in Figures 1 to

In the expanded condition, the structure is intended to present a relatively rigid load bearing space frame. It is therefore necessary to prevent the nodes 1 from collapsing totally onto the top of the nodes 2, and so the upper nodes 1 are interconnected by flexible tension members 4. The lower nodes are similarly interconnected by flexible tension members 5.

In the folded condition, the tension members 4 and 5 simply collapse as shown in Figures 6 to 9. As the structure expands, the tension members 4 and 5 reach the limit of their extension as shown in Figures 1 to 4, and thus limit the extent to which the nodes 1 and 2 can move towards one another.

The length of the tension members 4 and 5 is chosen dependent upon the shape and strength of the structure required. The thicker the structure, the greater will be its strength.

The tension members 4 and 5 may be made adjustable in length if required.

The tension members 4 and 5 may also be replaced by flexible skin members 6 and 7, as shown in Figure 10.

The way in which the links 3 and tension members 4 are attached is shown in greater detail in the embodiment of Figure 5. In this embodiment, each node comprises a hub 8 having six arms 9. Each arm 9 presents a pivotal axis 10, the six axes making up the sides of a regular hexagon. In other embodiments different polygonal shapes may be used.

Each link 3 is connected to the relevant pivotal axis by a pivot pin 11. The tension members 4 are secured to anchorage points 12, each anchorage point being positioned between two of the arms 9.

Preferably each upper node 1 is guided for sliding movement towards the opposed node 2, and in the component shown in Figures 1 to 9, nodes Id and 2d are mounted on a tie member 13 for sliding movement therealong.

Once the upper nodes and lower nodes have slid towards one another to the full extent of their movement, locking means may be provided to prevent them from moving back again, thus locking the structure in a condition such as that shown in Figure 10.

The ends of the tie member 13 may for example be screw threaded, so that nuts can be screwed on to the ends of the tie member to abut against the nodes Id and 2d. Alternatively, there may be a head at one end of the member 13 and a nut at the other end.

The invention provides a structure which can be arranged to cover a very large area or occupy a very large space, the structure being relatively strong, but relatively light in weight. It can be folded up into a very small volume. The structure is therefore particularly suitable as a basic frame component of structures that have to be deployed in space. It will take up a very small volume in a space vehicle when travelling out into space, but can then be quickly and simply deployed in space.

The high proportion of tension members to that of compression members helps to substantially reduce overall weight.

Structures having a curved surface may be provided by varying the lengths between the upper and lower groups of tripod members and tension members. The tension members, which preferably comprise cables, may be stowed, in the folded state, within the tetrahedral spaces generated in the framework of conjoined trusses. Similar stowage of the stressed membrane skin shown in Figure 10 could be accorded.

Alternative constructions are possible, and Figure 3 shows an arrangement in which the structure is biased into the expanded condition by compression springs 14 mounted on the ends of the tie member 13.

An alternative possibility would be to use a telescopic tie member 13 or a powered screw threaded member. The necessary power and control may be provided by any means, including pneumatics, hydraulics or electrics. More basic mechanisms could be used, such as a rope and pulley, for example where the structure is to be used as a stage lighting truss in a theatre.

Although the structure shown in Figure 10 comprises a double layer, it will be apparent not only that further modules could be added around the sides of the structure shown in Figure 10, to increase the area covered by the structure, but additional modules could be provided on top of the structure shown in Figure 10, or below, to provide multiple layers.

Although the connections shown in Figure 5 pivot about a single axis, universal joints could also be used.

In addition to the uses already mentioned, the invention could be applied to de-mountable roof trusses, scaffolding, dome structures, any space frame system, oil rig platforms, kites, false ceiling systems, exhibition display boards, electricity pylons, temporary housing or sun canopies.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.