Collapsible Reticular Structures

Abstract

Disclosed herein is a three-dimensional collapsible structure formed by an array of bar-like elements each pivotally connected at its ends to one or more other such elements. The elements and their pivotal connections are arranged to permit the collapse of the three-dimensional structure into a configuration wherein the elements are grouped closely together and disposed in parallel, whereby the collapsed configuration has an overall length which is substantially the same as the length of a single one of the elements.

Description

The present invention relates to three-dimensional structures, the geometries of which are specified hereinafter, and which are distinguished by their collapsibility and by the fact that, in the collapsed state, said structures, constituted by a plurality of bar-like elements, form compact arrays the lengths of which arrays do not substantially exceed the length of a single bar-like element.

The principle of collapsibility as a means of attaining small storage volume as well as portability is known and applied to three-dimensional structures. Patents have been granted for such structures (e.g., British Pat. Nos. 789,920; 791,189; 806,170; 923,231; 937,295; 1,006,972; 1,060,446; 1,123,791; and U.S. Pat. No.3,341,989) which, in their respective claims, are called collapsible, folding, demountable, portable, etc., and which are intended to serve as tents, garages, buildings and other structures. All the aforementioned inventions are characterized by the reduced bulk, in the collapsed, folded or otherwise demounted state, of their respective objects.

At this point, however, a definition should be introduced of the concept of "collapsibility" and a distinction established between the properties of "true collapsibility" as against mere "demountability." While the latter refers to the fact that a three-dimensional structure thus characterized can be nondestructively taken to pieces, stored and/or transported and, presumably, re-erected, true collapsibility, as defined for the purpose of the present application, is intended to refer to the fact that a three-dimensional structure thus characterized, while obviously demountable, constitutes in the collapsed or folded state a still coherent, or substantially coherent, whole, i.e., the elements constituting such a structure are still interlinked while the structure as such is substantially altered in shape and reduced in bulk.

A collapsible, grid-like structure of the kind which may be termed to fall within the general definitions given in the preceding paragraphs is described in British Pat. No. 1,009,371, wherein there is described and claimed, a collapsible reticular structure, comprising a plurality of groups of rods each of which consists of n rods jointed together at points intermediate their ends for relative articulation, each end of each rod of a group being jointed for relative articulation to the end of (n-1) rods of (n-1) further groups, the resultant three articulation axes of each rod being parallel and disposed transversely of the latter and lying in a common plane which also contains the longitudinal axis of the rod, at least some of the various joints interconnecting ends of the rods being themselves directly interconnected by means of flexible and unextendable means such as cables or ropes which act in direct tension to limit unfolding of the assembly of rods to provide a predetermined structure.

Perusal of the specification of said British Pat. No. 1,009,371 permits the following remarks to be made :

i. The collapsibility of the structures the subject of said patent is based on what may be termed the lazy tongs principle, these structures being in fact two-directional lazy tongs devices. With each of their elementary bars presenting three joints "intermediate, upper and lower," said structures must thus be regarded as three-layer grids.

ii. Structures covered by said British Pat. No. 1,009,371 show a need, inherent in the design principle, for additional stiffening elements such as cables or ropes; in fact three cable or rope systems, without which the structures would sag, or even collapse under their own weight.

iii. While the specification of said British Pat. No. 1,009,371 is very explicit about the manner of erection of the structures claimed, it does not describe the collapsing procedure. It is not clear how said structure can, in practice, be collapsed without detaching not only the individual "trans-layer" cables c, but also cable systems a and b mentioned therein which, upon collapsing the structures, would appear to form unwieldly and intractable loops. Need for removal and subsequent re-attachment of the cable systems would, on the other hand, increase the erection and collapsing times to such a degree as to make these structures quite impractical for the purposes envisaged for the structures of the present invention which are described hereinafter.

The invention described in the present application is distinguished from the invention described in said British Pat. No. 1,009,371 in a number of aspects detailed herebelow.

Re (i): The collapsibility of the structures according to the present invention is based on an altogether different principle: to collapse the structure of the present invention, the elementary bars are caused to "jackknife," the ensuing "spatial zig-zag" then being progressively compressed until the bars are substantially parallel and form a compact array. Since, in consequence, each of the elementary bars of said structure has two joints only, it can be held to constitute single-layer or, in different embodiments, double-layer grids, i.e., all the joints are located on one curved surface (dome-like or cylindrical) or, in the second case, on two such surfaces (concentric or coaxial) of slightly different radii. This distinction is quite an important one since, in practice, a three-layer grid would be quite unfeasible for structures of the relatively large curvatures (R.about.1.5 times the length of the elementary bar) envisaged by the present invention.

Re (ii): The structures according to the present invention are self-supporting by virtue of their geometry and the design of their joints, and any additional stiffening means suggested or required only serve to counter extraneous, concentrated or accidental forces. Furthermore, such stiffening means as may be advisable to use can be activated after erection and deactivated prior to collapsing in a matter of seconds.

Re(iii): The structures according to the present invention can be erected and collapsed within minutes and, as indicated in the preceding paragraph, the possible application of additional stiffening means does not substantially add to this time. The sum of erection and collapsing times thus constitutes only a fraction of the likely period of use of these structures, a precondition for the useful application of collapsible structures to such purposes as envisaged by the present invention.

It is thus seen that the structures of the present invention are distinguished from said British Pat. No. 1,009,371 in several important and material aspects having a direct bearing on the design and utilities of the respective structures. It is also seen that none of the other aforementioned inventions dealing with structures claimed to be collapsible, folding, demountable, portable, etc., do in fact conform with, or fall within, the definitions, restrictions and utilities so far presented and further described hereinafter.

A brief description can be found in "The Dymaxion World of Buckminster Fuller" by Robert W. Marks (Reinhold Publishing Corporation, New York, 1960, p.195) of a collapsible reticular structure which shows some formal similarities to the present invention. Said structure is claimed to be an experimental project carried out by Washington University, St. Louis, Miss. A more detailed description of the same structure is given in "World Design, Science Decade 1965-1975" by R. Buckminster Fuller, World Resources Inventory, Southern Illinois University, Carbondale, Illinois, U.S.A., 1963, pp.51/52, reading as follows:

"As you see all the structural members are in parallel in this first picture so that they may be transported in minimum volume in a rocket capsule. The parallel struts of light weight magnesium alloy consist of sets of three fastened together with a ball joint in tripods. Each set is like a camera tripod with three tubular magnesium legs. It has ball joints at the tripod head. Then all the tripods' feet are fastened together with ball joints in clusters of 5 and 6 tubular-tripod feet per ball joint. We have a little mast coming out of the top of each tripod. This mast is pushed out automatically by a piston in a cylinder. We put 200 pounds of gas pressure inside the cylinder and this gas pressure will push the masts on all the tripods outwardly from each of the tripod heads. The pushed-out masts each have three tension members leading to their respective tripod's feet. As the masts are pushed out by the 200 pound pressure the tension members pull the legs of the tripods outwardly from one another. The tripods all open wide with their ball joint feet fastened together in hexagons and pentagons. There is a triangular net of aircraft cable in a regular geodesic "star" spherical grid, -- like the pneumatic ball's tension net, that restrains the tripod legs from moving any further outwardly from one another than is necessary to form a dome or sphere."

Perusal of the available text and photographs permits the following remarks:

I. Although the aforesaid structure ("Flying Seed Pod" -- FSP) is labeled "foldable," it is quite obvious that the primary concern of the design was with rapid and effortless erection, while hardly evincing any thought as to the collapsing of the structure. It is possible to arrive at this conclusion not only because of the absence, in the available texts, of any description concerning the collapsing procedures, but mainly by way of analysis of both the structure itself and its declared utility.

a. The "FSP" structure

The structure having been erected according to the explanations cited above, it now becomes necessary to immobilize the "masts" in their pushed-out position, in order to keep the cable systems tight and said structure erect. In principle this could be accomplished in two ways: pneumatically or mechanically. As to the former, this would either mean shutting off the air pressure and assuming that all cylinders, pistons and other sealing points are airtight enough to keep the masts up for whatever period the structure is to be used. As such an assumption is not very realistic, the other pneumatic solution would be to have the structure permanently connected to a sufficiently large compressed-gas source, a solution even more clumsy and only slightly less unsafe. There remain thus the mechanical solutions of which there exist, of course, any number. Basically, such a locking device could be manually actuated, e.g., a pin pushed into a transversal hole in the mast, preventing it from sliding back once the pressure is relieved or reduced. A more elegant solution would be a spring-loaded catch which, similar to the umbrella catch, would permit the mast to extend, but prevent it from withdrawing. Whatever the solution applied, these locks or stops would have to be manually released, one by one, before the structure could be collapsed. As said structure cannot be collapsed tripod by tripod, to achieve a controlled collapse (as opposed to a "catastrophic" collapse), this would seem to pose a most serious problem, unless, of course, as is contended here, said structure was never intended for collapsing after erection, not to speak of frequent collapsing and reerection. This is also borne out by:

b. The utility of the "FSP" structure

Concerning utility, both sources are quite explicit. B. Fuller states in "World Design Science Decade," p. 52:

"We have the proven ability to capsule, parallel packed, geodesic, tensegrity structures for rocketing to the moon, or to the top of an earth mountain, or to other far earth points to be self-opened in seconds."

Robert W. Marks in "The Dymaxion World of Buckminster Fuller." p. 195, talks of

". . . air-droppable and rocketable, remotely installable, controlled environments."

II. Apart from said tubular "FSP" structure which can indeed be claimed to show a formal similarity to one particular embodiment of the present invention, it comprises further elements essential to its very stability, namely, the masts as well as the two cable systems referred to in the above explanation. Now, while the mobility feature of the masts is required merely for erection, the masts in their extended position and the two cable systems are definitely required to "lock" the structure and keep it from sagging and collapsing. If the cables were out, the structure would collapse under its own weight.

III. The three legs of each tripod which, with their corresponding three cables, constitute in themselves a pyramidal system, can be regarded as one layer, and the triangulated, spherical cable grid as a second layer of a double-layer structure the stability properties of which are determined by the distance between these two layers.

The invention described in the present application is distinguished from the afore-described prior art in a number of aspects detailed herebelow:

Re (I) above: The structures claimed by the present invention are truly collapsible or foldable not only in the sense defined on pp. 1 and 2 hereof, but also in the sense referred to under (I) (see above), namely, in that we have in our design paid equal attention to "erectability"and "collapsibility," collapsing, if anything, taking even less time than erecting. The collapsing procedure appropriate to one of the embodiments of the present invention, e.g., the dome-like structure represented in the hereinafter mentioned FIGS. 1 and 2, is as follows:

1. The five lowermost joints 2D (FIGS. 1 and 2) on which the structure rests are flipped over until substantially perpendicular to the central one of their three bar-like elements.

2. The locking disks (9) (FIG. 4) mentioned hereinafter are detached by turning them about a quarter turn.

3. The uppermost (central) joint 2A (FIGS. 1 and 2) is pulled down, inverting the top vertex of the structure. As during this, and subsequent, collapsing steps, first of all, and later at least some of the bar terminals are still angularly defined in one or two planes due to the special design of the joints, the slight strain induced by the inversion of the inward-folding vertices produces enough friction to permit these inversions, i.e., in effect, the collapsing, to be accomplished in a "controlled," as opposed to a "catastrophic" manner.

4. The rest of the inward-folding vertices are inverted by pushing them inward, the "controlled" effect applying here, too.

5. The now spider-like, essentially collapsed structure is turned into an array of practically parallel bars by pushing all five "spider legs" toward the center. The need for frequent reerection, i.e., for simple and rapid collapsing is also implied in the utilities envisaged for the present invention, which includes such uses as tents and bungalows for outings, picnics and on the beach and similar short-time uses precluding any complicated and time-consuming erection and collapsing procedures.

Re (II) above: As stated in the claims of the present application, the structure according to the said invention is "self-supporting by virtue of its geometry and the design of its joints." Removal of such non-protruding, non-cable like and, therefore, non-snarling, locking devices as are suggested by the present invention would still leave these structures standing.

Re (III) above: The structure according to the present invention is strictly a single-layer structure and, therefore, both structurally and morphologically speaking, essentially different from the double-layer structure represented by the said "FSP" structure.

It is thus seen that the structures of the present invention are distinguished from the afore-mentioned prior art in several important and material aspects having a direct bearing on the design and utilities of the respective structures, one of the principal features of the structures of the invention being the particular design of the joints offering different and carefully determined degrees of freedom to the respective terminals of the bar-like elements and presenting indent, guide and stop features fully defining the angular position of their associated bar-like elements both with respect to each other and with respect to the central axis of symmetry of each vertex so as to define and delimit the unique angular position of each bar-like element within the whole structure as dictated by the geometries of the whole.

Another known structure, the subject of U.S. Pat. No. 3,059,658 (Thomas R. Finlayson) claims a "Shelter Framework" which may be deemed pertinent to the present invention inasmuch as it bears a certain formal resemblance to one particular embodiment of the present invention. The structure covered by this U.S. Patent claims to be collapsible and, when collapsed, to form a compact bundle, with its constituent strut elements in a substantially parallel relationship. The structure claimed by the above reference derives its rigidity and stability from the fact that it is completely triangulated, i.e., the polygons constituting its spatial configuration are triangles, the horizontal bases of which are formed, on the one hand, by the "eave struts" and, on the other hand, by the means interjoining the ground-engaging ends of the support struts or, in absence of such means, by the ground itself to which the structure must be firmly anchored. Now, as a polyhedral structure can only be completely collapsed if its constituent polygons have 2n sides, the structure, prior to collapsing, must be turned from a triangulated one (a triangle having 2n-1 sides) into a quadrangulated one. This can only be done by eliminating said horizontal bases of said triangles, i.e., the "eave struts" as well as said interjoining means on the ground, be they cable or strut means or, in absence of such, anchorage to the ground.

The present invention is distinguished from, and constitutes an improvement of, the invention of said U.S. Pat. No.3,059,658 by the fact that, its constituent polygons, having 2n sides, it can be completely collapsed without prior removal of some of its structural elements. Most important, however, whereas said known structure would immediately collapse without said means holding its ground-engaging ends in a stable position, the present invention is inherently self-supporting by virtue of its geometry and, in particular, the design of its joints, as explained in the comment on the above-mentioned B. Fuller disclosure. The present invention can therefore in no way be said to be derived from the invention of U.S. Pat. No. 3,059,658.

According to the invention there is provided a reticular, three-dimensional, jointed structure constituted by a plurality of joints and a plurality of rectilinear, substantially rigid, bar-like elements mutually jointed and articulated by said joints, said structure conforming to geometries based on polyhedra constituted by plane or spatial polygons having 2n sides, said structure being collapsible, wherein said joints include integral indent and/or guide and stop means which fully define and delimit the unique angular position of their associated bar-like elements both with respect to each other and with respect to the central axis of symmetry of said joints, which indent and/or guide and stop means enable said structure to be intrinsically self-supporting once completely erected, and wherein said joints are designed so that at least some of said bar-like elements may move with more than one degree of freedom at least to some extent relative to their associated joints, while the other bar-like elements are constrained relative to their associated joints so as to be restricted to movement in one plane only and that in the collapsed state of said structure, the array formed by said bar-like element is of a length substantially equal to the length of a single bar-like element.

Regarding the geometries of the structures of the invention, it can be stated that the basic shapes underlying said structures are either spherical (dome-like) or cylindrical, in which latter case the axis of symmetry of the cylindrical envelope, being also the axis of the structure, can be either parallel or perpendicular to the ground. Cylindrical structures with a vertical axis of symmetry can be closed off at the top by adding a pyramid having an n-gonal symmetry identical with the symmetry of the cylindrical grid. The totality of said bar-like elements, interconnected by an appropriate number of joints, thus constitutes a spatial grid substantially outlining said underlying basic shapes and, as described above, consisting of a number of spatial polygons having 2n sides.

Concerning said joints, it should be noted that their design is such as to permit at least some, but possibly all, of said bar-like elements to move with more than one degree of freedom, said term as herein used referring to any one of the six possibilities of motion of a movable body relative to a fixed system of coordinates (three translations parallel to the coordinate axes and three rotations about these axes), while constraining other bar-like elements in such a way that, relative to one or both of their associated joints, said other bar-like elements may be restricted to movement in one plane only.

As to the actual number of bar-like elements required for a specific embodiment of the invention, it should be pointed out that this actual number is either equal to the ideal number of bar-like elements as prescribed by the theoretical configuration of the structure, or different from this ideal number, in which case one or more elements are either removed or added to provide for access to the structure or connecting apertures or passage ways between a plurality of said structures, or any combination thereof.

A further feature of the structures of the present invention is the fact that, with the aid of joining elements, one such structure can be joined to, and combined with, one or several identical or similar or even dissimilar structures in such a way as to create a new structure, more complex than said basic structure.

Although the structures proposed by the present invention can in principle be regarded as self-supporting, extraneous or concentrated or accidental forces may be countered by immobilizing or rigidifying at least some of said articulated joints with the aid of locking devices which are either integral with, or attachable to, said joints.

The proposed structures do not require supporting members within or without the space enclosed by them and can be anchored to the ground with or without the aid of guy ropes.

The structures of the present invention may be covered by at least one pliable covering skin which can be attached to either the inner or the outer skin of the structure, or with a plurality of skins some of which can be attached to the inner side and some to the outer side of the structure. Said structure can be collapsed and/or erected with said skin or skins in situ or, alternatively, said skin or skins may be attached to said structure after erection and removed from said structures prior to collapse. These skins can be made from any pliable material, such as fabrics from natural or synthetic or mixed fibers, and also from rigid or semi-rigid sheet material (metallic, plastic, paper, mineral, etc.). In the latter case, these sheets can be joined to each other and to the structure by such known processes as lacing, cementing, welding, riveting, etc., and/or by a plurality of properly located and shaped connectors such as hooks, rings, clamps, links, etc.

The structures of the invention can be used as tents and bungalows for outings, picnics and on the beach, as self-contained stands for exhibitions and fairs, as first-aid stations and emergency hospitals, as temporary storage facilitiates and movable packing sheds, temporary work camps and the like.

For a better understanding of the nature of the structures according to the invention, a description thereof will now be given, based on the accompanying drawings which illustrate, simply and diagrammatically and by way of example only, some preferred embodiments of said invention and wherein :

FIG. 1 is an elevational view of a dome-like structure according to the invention;

FIG. 2 is a plan view of the structure of FIG. 1;

FIG. 3 represents in perspective view a specific embodiment of a bar-like element;

FIG. 4 shows in perspective view a particular embodiment of a ball-and-socket type of joint;

FIG. 5 is a perspective view of another embodiment of a ball-and-socket type of joints;

FIG. 6 illustrates a lug-and-fork type of joint;

FIG. 7 represents a compound structure obtained by joining together two structures such as shown in FIG. 1;

FIG. 8 shows the coherent array of bar-like elements as represented by a completely collapsed structure such as described, e.g. in FIG. 1;

FIG. 9 and FIG. 10 illustrate a further embodiment of the structure of the invention, based on a different geometry, in plan view and elevational view respectively.

Apart from the general shape of a particular embodiment of the invention, FIGS. 1 and 2 also indicate the precise location of all bar and joint elements. Here numerals 1 denote the bar elements and 2, the joint elements. The different types of these elements are indicated by letters. Accordingly,

1b: bar-like element with one lug-type and one ball-type terminal (see FIG. 3);

1A: bar-like element with two lug-type terminals;

2A: lug-and-fork type joint, accommodating 5 bar-like elements 1A;

2B: lug-and-fork type joint, accommodating 3 bar-like elements (see FIG. 6);

2C: ball-and-socket type joint, accommodating 5 bar-like elements (see FIG. 4);

2D: ground-touching joints. According to their geometry, these are essentially of the 2C type, except that they accommodate only three bars each, the central one of which, lying in a meridional plane of the spherical configuration, does not require the freedoms of motion afforded by the ball joint and, therefore, can be of the lug-type.

One particular embodiment of an entrance opening, marked in FIG. 2 by an arrow, is delimited by joints and bars 2D.sub.d -1A.sub.d -2Bd-1B.sub.d -2C.sub.d 1B.sub.d -2B.sub.d -1A.sub.d -2D.sub.d. Joints 2D.sub.d and 2C.sub.d each accommodate one bar-like element less than their non-subscripted namesakes.

The bar-like element itself, which may be either hollow or solid and consist of any suitable material such as ferrous or nonferrous metals, plastics, wood, or any combination of such materials, is shown in greater detail in FIG. 3, which is a preferred embodiment and in which body 3 thereof is shown as attached at one of its ends to a spherical terminal 4, constituting the ball of a ball-and-socket type joint, the other end being attached to a flat tongue 5 constituting the male element of a lug-and-fork type joint. Fixed to tongue 5 is a pivot 6.

A specific embodiment of a ball-and-socket type joint is illustrated in FIG. 4, which shows two halves 7 and 8 forming the body of said joint, an attached locking disk 9, a T-shaped nut 10 holding down the locking disk 9, a bolt 11, a head 12, which has a hook-like shape serving for attachment of the covering skin, and U-shaped indents comprising stop means 13 and guide means 13a, which serve to define the position of the bar-like elements relative to said joint, once the structure is completely erected. One end 14 of such an element is ghosted-in. Upon collapsing of the structure, the locking disc having duly been removed the balls necks can, at first, move only in one plane, being still confined between the parallel walls of the U-shaped indent. However, once the ball neck has moved beyond the indent, the bar-like elements and the body of the joint are able to perform the complex relative movements required for convergence of the joints and juxtaposition of the bar-like elements to form the compact array shown in FIG. 8. Upon erection of the structure, the ball necks can freely follow the complex, not necessarily symmetrical pulling forces, until they make contact with the guide surfaces 13a which eventually ease them into the U-shaped indent, where their motion is finally brought to an end by the stop surfaces 13.

Another embodiment of a ball-and-socket type joint is shown in FIG. 5. Here, the locking device is an integral part of the joint and consists of a cup 15, rotatably mounted on one of the joint halves and provided with a number of peripheral slots 16 which, in the open state of the lock, permit the ball necks to be introduced and seated in the U-shaped positioning indents 16a. Rotation of the locking cup 15, facilitated by gripping tabs 17, causes the indent exists 16b to be blocked, thus preventing the ball necks from leaving their respective indents.

A preferred embodiment of a lug-and-fork type joint is illustrated in FIG. 6. This joint permits its members to move in one plane only, as the guide slots 19a are, substantially, of the same width as the lug 22. In this embodiment, the two halves 18 and 19 are held together by a bolt 20 having a hook-shaped head 21. The ghosted-in lug-type end 22 of the bar-like element 23 is provided with a pivot 24 rotatably seated in one of the joint halves. The bottom 18a of the upper-half guide slot serves as a stop.

In FIG. 7, two dome-like structures of the kind seen in FIG. 1 are joined together to form a larger, more complex structure. Here, the basic structures are denoted by 25 and 26, and the joining accessories by 27 and 28.

The coherent array of bar-like elements as represented by a completely collapsed structure of the kind seen in FIG. 1, is shown in FIG. 8. The closely folded bar-like elements are in the collapsed state substantially parallel, some of the joints coming to rest on top of the array and some at the bottom. In the example shown, the covering skin has been removed prior to collapsing of the structure, although this is not necessary in practice.

Another embodiment of the proposed structures is depicted in FIG. 9 and in FIG. 10. This is a basically cylindrical structure with a vertical axis of symmetry, closed off at the top by a pyramid.

Herebelow is a description of a preferred erection procedure of a certain embodiment of the invention, with reference to FIGS. 1 and 2 of the drawings:

i. The bundle of parallel bar-like elements (schematically represented in FIG. 8) is put on the ground, with the bar-like elements in a substantially vertical position and with the ball-and-socket type joints touching the ground.

ii. The five peripheral ground-touching joints 2D (FIG. 8) are pulled outwardly in a radial direction as far as they will move, imparting to the structure, at this stage, a spider-like appearance.

iii. One of the persons engaged in the erection of the structure (called in the following an "erector") then lifts up the two upper bars 1B (FIG. 2), which delimit the entrance opening, thus permitting a second erector to position himself underneath the now partly distended structure.

iv. The second erector now lifts up the central joint 2A, holding it high, while the first erector pulls out the peripheral five-member joints [including the four-member joint 2C.sub.d (FIG.2) of the entrance opening. ]

v. The five ground-contacting joints 2D (FIG. 1 and 2) are manually tilted outwardly as far as they will go and the locking disks 9 (FIG. 4) are now applied to each of the five ball-type joints 2C by first pulling these joints outwards until all the ball necks are properly seated against the stops 13 (FIG. 4) of their respective indents, then the locking disks are put on, with their slots 9a (FIG. 4) parallel with the T-nut 10 (FIG. 4) and, finally, turning said disks about a quarter of a turn. The structure is now erected and may be anchored to the ground, if conditions so require.

The collapsing procedure has already been described on pages 10 and 11 of this specification and is, in effect, more or less a reverse procedure to that described in respect of the aforementioned erection procedure.

Claims

We claim:

1. A collapsible, reticular, three-dimensional, jointed structure, self-supporting by virtue of its geometry and the design of its joints, said structure conforming to geometries based on polyhedra constituted by plane or spatial polygons having 2n sides and comprising a plurality of joining means and a plurality of rectilinear, substantially rigid, bar-like elements mutually connected together and articulated by said joining means, said joining means including integral guide and stop means which fully define and delimit the unique angular positions of their associated bar-like elements both with respect to each other and with respect to a central axis of symmetry of said joining means, and which guide and stop means enable said structure to be intrinsically self-supporting once completely erected, said joining means also including means for permitting a first portion of said plurality of bar-like elements to move with more than one degree of freedom relative to their associated joints, and for constraining a second portion of said plurality of bar-like elements to movement in one plane only, wherein, in the collapsed state of said structure, the array formed by said bar-like elements is of a length substantially equal to the length of a single bar-like element.

2. A structure according to claim 1, wherein the actual number of bar-like elements provided therefor is either equal to the theoretical number of bar-like elements as prescribed by the configuration of said structure, or different from said theoretical number, in which case one or more elements are either removed or added to provide for access to the structure, or connecting apertures or passage ways between a plurality of said structures, or any combination thereof.

3. A structure as set forth in claim 1, further comprising at least one additional said structure and a plurality of joining elements connected between said structures, whereby said structures are combined to provide a more complex composite structure.

4. A structure according to claim 1, wherein a plurality of said joining means include locking means for immobilizing selected ones of said bar-like elements.

5. A structure according to claim 1, further including means connected thereto for anchoring said structure to the ground.

6. A structure according to claim 1, further comprising at least one pliable covering skin attached to said structure at a plurality of positions.

7. A structure according to claim 6, wherein said pliable covering skin remains in situ when said structure is collapsed.

8. A structure according to claim 6, wherein said skin or skins are attached to said structure after the erection thereof and are removed therefrom prior to the collapse thereof.

9. A structure according to claim 1, further comprising a plurality of preformed sheets of covering material attached to each other and to said structure.

10. A structure as set forth in claim 1, in which one of said joining means comprises first and second plate-shaped members having radial slots therein, said slots in said first plate-shaped member extending through the entire axial extent thereof, means for connecting said plate-shaped members in a face-to-face relation wherein said slots are disposed in alignment, one of said plate-shaped members having pairs of aligned notches disposed therein and projecting transversely of the walls of its said slots, one said pair of notches for each said slot, and in which each of a plurality of said bar-like elements has a lug shaped end portion and a pair of rigid pivot members extending transversely of said lug portion in opposed alignment, wherein said lug portions of said bar-like members are received in said respective slots, and said pairs of pivot members are received in said pairs of notches, whereby said bar-like members are pivotable with respect to each other on said connected plate-shaped members.

11. A structure as set forth in claim 1, in which one of said joining means comprises a plate shaped member having a plurality of radially disposed socket openings extending therethrough and positioned to define slots through the peripheral edge thereof, a circular member having a plurality of notches extending radially therethrough, means for connecting said plate-shaped and ring-shaped members together wherein said slots and notches are disposed in alignment, and in which each of a plurality of said bar-like elements has a pin, and a ball interconnected to one end of said bar-like element by said pin, said pins being received, respectively, through said openings, each said ball having a diameter larger than said openings, and each said pin having a diameter smaller than said slots and notches.

12. A structure as set forth in claim 11, in which said circular member has a plurality or circumferential slot means in communication respectively with said notches for receiving said pins to releasably hold said bar-like elements against movement.