FR2589982A1 - Foldable structure especially for space - Google Patents

Abstract

THE STRUCTURE INCLUDES A NUMBER OF BARS OR THE LIKE 10 TO 17 ESSENTIALLY RIGID AND JOINTED IN AN ARTICULATED WAY, WITH SPRINGS 22, 23 COOPERATING WITH AT LEAST A PART OF THE ARTICULATING POINTS 6 TO 9 CONNECTING THE BARS OR THE LIKE BARS, FOLLOWING THE DIRECTION OF FOLDING AND DEPLOYMENT, IN THE DIRECTION OF FOLDING OR DEPLOYMENT. SEVERAL ELEMENTS 1 RELATED TO THEY ARE PROVIDED, INCLUDING EACH TWO FOUR-BAR GAMES 10 TO 13, 14 TO 17 AND SIX POINTS OF ARTICULATION 4 TO 9 LAYERED FOLLOWING THREE PAIRS MUTUALLY COOPERATING, AT ANOTHER, TO THE OTHER AND TO THE MIDDLE , THE TWO POINTS 4, 5; 6, 7; 8, 9 OF EACH PAIR BEING MOBILE TRANSVERSELY TO DEPLOYMENT MANAGEMENT, TWO BARS 10, 13; 14, 17 OF EACH GAME RESIDING ON ONE SIDE OF THE MEDIUM DEPLOYMENT LINE AND THE TWO OTHER BARS 11, 12; 15, 16 CROSSING THIS LINE CROSSING EACH OTHER.

Description

Foldable structure, especially for space
The present invention relates to inwardly folding space structures. and outwards, of the type comprising a number of essentially rigid bars or the like which are articulated in connection, with springs cooperating with at least part of the articulation points connecting these bars or the like and pushing them back in the direction of the folding and unfolding, in the direction of folding or unfolding.

 One can for example use such a structure in the form of a mast, to carry solar panels in such a way that, when this structure is retracted, these panels are folded and can thus be transported tightly, by example to bring them into space and to, after a stay in space, bring them back to earth, and in such a way that they can be deployed totally or partially in the desired location, for example on a machine spatial, in order to place them in their working position.In one embodiment in platform or disc form, one can use such a structure to support an antenna, or other body, in disc form (for example dish), which is thus supported, ---- so as to be deployed from a spacecraft and to be retracted towards it. We also aim to have a structure such that, if desired, it can, thanks to a variable degree of deployment, orient the parts that it carries, for example solar panels or antennas, at an angle variable with respect to the carrier body, and therefore also with respect, for example, to the earth or to the sun, without it being necessary to modify in this process the position of the carrier body, for example of the spacecraft.

 Known structures of this type comprising rigid bars and arranged so as to form masts or discs often present articulated bar systems (systems with extendable clamps), examples being present in the following patent memories: FR 511 503 , GB 797 376, US 3 460 992, US 3 496 687, DE 651 642, FR 2 254 176 and EP 136 985. In other known structures of this type, there are bars arranged so as to bend - - at a point between their ends, for example in US 4,482,900, US 4,276,726 and DE 2,941,170. In other known structures, the length can be varied telescopically bars, for example in DE 3,044,630. Combinations of such systems are also contacted.

 For such structures which must be used in outer space, it should be avoided that cables, which are used to fold or deploy these structures or to give mechanical resistance to the deployed structure, present soft in the extended or extended state of the structure in the weightlessness state of the spacecraft. In view of this, articulated lever systems as present in FR 511 503 and in GB 797 376 are not suitable for use in space.

 US Patent 3,460,992 describes a battery of deployment solar panels having extendable clips on the legs of which the solar panels are arranged by projecting each from one side of the leg of these expandable clips, thus projecting entirely on the one and the other ribs. There are provided, in the points of articulation of the legs of these clamps, helical springs which repel these legs in the direction of deployment towards the outside of the panels. In such a structure, due to their low design height, the clamps have a low lateral stiffness against bending in their plane of movement, so that the system is not suitable for an elongated battery of solar panels.

In this regard, account should be taken of the fact that there is such a structure with extendable clamps between two rows of elements such as solar panels, the dimensions of which are for example 1.5 times 2 m for each, which gives has the battery a deployed length of 40 m.

Due to inevitable movements of the battery, the legs of the clamps will not only be loaded by tensile and compressive forces, but also by bending moments. For large deviations of the battery and with insufficient elastic damping of the movements, the energy production of the battery will remain below forecasts. In particular in the case of a battery of very elongated or slender solar panels having low rigidity against the bending and twisting of the panels, it will be necessary to use a rigid mat.

 The system with extensible clamps of US Pat. No. 3,496,687 is kept in shape by three cable passages. By shortening the intermediate target, which describes a zigzag path, and by simultaneously unrolling the external targets, the articulation points are placed under load, so that the mast is deployed. The limitation of the deployment length, the shortening and a certain curvature of the deployed mdt are obtained using the two external targets. Thanks to a difference in the length of the legs of the bars, a curved structure is obtained. The structural rigidity of this mat is thus based on the rigidity of the legs of clamps (bars) which together form the mat, and / or on the rigidity against elongation of the cables.

 In the structures of patents DE 651 642, FR 2 254 176 and EP 136 985, the structural stiffness of the entire structure is obtained and is only based on the structural stiffness of the bars.

 Such drawstring structures have the disadvantage of not providing suitable junction points for solar panels, or the fact that, but this is true for stretchable clamp structures in general, --------- --- each point of articulation, and any point, of the structure is not arranged so as to be used for the application of an external load.

 Among the other structures given in the patent memories mentioned above, in which the bars can be folded or varied in length in a telescopic manner, US Pat. No. 4,482,900 presents a structure assembled to starting from basic elements of cubic shape, with articulated connections of bars forming the sides of the cubes at the place of the vertices of these cubes.

 The bars forming the ribs of the upper and lower face also have a joint halfway along their length, while the lateral faces of the cubes have a diagonal, the ends of these diagonals being connected in an articulated manner one to the other. other at the point of the vertices of the cube. When this basic element is folded, the sides of the top and bottom move in the plane of the side face and the sides connecting the face of top and bottom move parallel to one another. The structure is designed to deploy the platform once, then to maintain it in its final position. The elastic force which acts, among other things, in the central joints of the subdivided ribs causes the folded ribs to deploy fully and their keeps the final positions reached. You cannot retract a platform which is assembled from many of these basic elements of the same shape, since the subdivided ribs of all the basic elements are not forced to fold under the effect of an external force.

 United States patent specification 4,276,726 discloses a different structure. Again, the geometry of the base fold is a collapsible cube, but without bars along the sides. In the four lateral faces of the cube, there are two diagonals which intersect one another and are connected in an articulated manner at their point of intersection. The rear face of the cube has no diagonals. In the front face, the diagonals are interrupted at the point of intersection and there have an assembly joint. This articulation is provided in such a way that during the folding of the cube the articulation comes out of the front face and a spacer in the form of a pyramid is formed with the halves of the diagonals. During deployment, the halves of diagonal of the central joint return to the front face of the cube. Given that the toisenient of bars formed by the cube constitutes an articulated unit, dimensional stability is only obtained by fixing said joint joint by means of a bar provided in addition. To maintain the shape of the entire platform which has been obtained, such an additional bar must be provided in all the basic elements. This means that the platform cannot be folded down by releasing only one locking mechanism.

 Another example of a bar mechanism is disclosed in United States patent specification 4,290,244.

 The basic element of this one is a system made up of rigid bars in the shape of pliers moving in scissors. Thanks to the scissor movement, the bars are also loaded by transverse forces, which means that, to give these bars as much bending stiffness as necessary for the basic element to have sufficient dimensional stability, the bars in equilibrium must have either more weight or larger external dimensions than if only tensile and compressive forces prevailed. The characteristic difference compared to the systems mentioned above lies in the fact that the surfaces formed have no not all articulation points of a basic element and that bars can even come out of the surface, which means that the structure does not meet the criteria set for a platform. The structure has the characteristic that each position of this structure between an almost total folding and an almost total deployment can be fixed by locking in principle only one basic element.

 Because of the way of folding and unfolding them and of the fact that the bars or the like are only subjected to traction and compression and not, If not little, to bending, of such known structures are not ideal for platforms or support surfaces, for example for an antenna, in space, which must be able to be folded and deployed in a simple manner from a point or a small number of points, by providing a maximum number of connection points forming a good support for connection parts to be supported thus, while constituting a light embodiment.

 The object of the present invention is to improve such a deployable structure so that on the one hand it is possible to produce the parts such as the solar panels which it carries by giving them a low weight, while however obtaining in the deployed position and in the intermediate stages a robust unit which is also resistant to transverse forces, and so that this is obtained with a structure which can be deployed and folded up by means of a mechanism as simple as possible, while taking up little space in the state collapses.

 Another object of the invention is to construct a spatial structure which can be deployed and folded up from substantially identical base units and in which all the articulation points are positioned in the external faces of the structure. deployed, practically all of these points may be suitable for being used as a connection point for parts to be carried by the structure such as solar panels.

 To this end, a structure in accordance with the preamble is, in accordance with the invention, characterized in that said structure comprises a certain number of elements, each forming two sets of four bars or the like and six points of articulation forming three mutually cooperating sets of two articulation points, two at one end when looking in the direction of folding and loosening, two at the other end, and two between them, while the two articulated points of each game are each movable transversely to said direction towards and away from one another, two bars or the like of each set extending between adjacent articulation points each of which belongs to a different set of points of articulation, on one side of the median line of the element which extends in the direction of folding and deployment, the two other bars or the like of each set each extending, between two bars or the like of the same set, on the two ribs of the said center line, these two other bars or the like being connected in an articulated manner to the said bars or the like on one side of the said center line so as to cross each other in a mobile manner, and in that a certain number such elements are usually connected in an articulated manner by sets of two articulation points located at one end of each element.

 This not only provides an improvement over the known structures with regard to the disadvantages of these mentioned above, in order to achieve the aims set out in the invention, but it also makes it possible to obtain many different forms of structures. , in principle either in the form of a platform, or in the form of a mast.

 In the case of a platform, the structure is preferably further characterized by the fact that a certain number of bearings are connected together by such end articulation points so as to form, in a plane which is transverse to the planes of the element, equilateral polygons.

 In order to obtain dimensional stability in a plane transverse to the plane of the elements without additional means for this purpose, it is preferred to arrange the elements, at least for the most part, according to equilateral triangles.

 Such a structure can be made very light and can be folded and deployed from a single point, or if desired from a few points, by moving two points of articulation of a game (of the same end d 'a Blément, and called cooperating points of articulation), in direction and away from each other. It is possible to immobilize or lock the structure in the fully deployed position, and also if necessary in intermediate states, by keeping said articulation points locked with a fixed distance between them.

 Preferably, articulation points of the structure according to the invention are used to serve as fixing points for parts of a platform, an antenna or the like which must be carried. In this case, the structure according to the invention has the advantage that all the points of articulation are located in the external faces of the deployed structure.

 In this deployed state, the structure does not need to form a flattened plane. Thanks to the use of length differences in bars or the like, so that they are on one side of the elements shorter than on the other side, one can obtain a structure which forms a concave or convex working face, for example a platform or antenna face.

 It is possible to fix in the points of articulation or in some of these, or between these points of articulation, springs which force bars adjacent to the point of articulation to take a particular position one with respect to each other or which force points of articulation towards each other or away from each other. In this case, one can choose between springs which force the structure to deploy or fold back. The forces to be applied from the outside for the folding or the deployment must then work against the said efforts of the springs for one of these movements. These springs can be arranged in, or between, some of the points of articulation in such a way that they work more particularly, or only, in the first phase of deployment or folding, while springs arranged in, or between, other points of articulation work more particularly in the phase final of these. It is possible to use helical springs in the articulation points, these springs having projecting ends and adapting to adjacent bars or the like or to stops provided thereon, in order to force these bars to adopt an angular position determined with respect to each other.

 Such springs also have the advantage that there is no damage from games in the points of articulations since these springs destroy these games because their forces are directed in one direction, which is particularly important in the deployed state to obtain a well defined extreme position.

 Since these springs increase the forces which are necessary to move the structure against the force of these springs, it may be desirable to apply external forces then more than a set of articulation points. coo piercing, for example on a number of points distributed symmetrically over the entire periphery of the structure.

 In the case of a mast, a structure according to the invention is preferably characterized in that a certain number of such elements are connected to each other in a series connection, two points of articulation situated at one end of a element being joined at two points of articulation located at the other end of another element.

 If this structure is used to carry solar panels, it is preferably connected directly to a part of the elements and they are not connected in a directly articulated manner to one another. The arrangement of these solar panels can be optimal as regards their operation, since, as regards the structure, they need to contribute little or not at all to the mechanical resistance of the structure of the type mast.

Other characteristics and advantages of the invention will emerge from the description which follows, with reference to nonlimiting examples and with reference to the accompanying drawings in which:
- fig. 1 is a view of an element of the type used in the assembly of a structure according to the invention, largely but not completely folded back,
- fig. 2 is the same view of this fully deployed element,
- fig. 3 is the same view of two adjacent deployed elements, the corresponding bars being of different lengths,
- fig. 4 is a view, perpendicular to that of FIGS. 1 to 3, for a platform according to the invention and made up of such elements, being in the deployed position,
- fig. 5 is a schematic view of a mast-type structure according to the invention, in the deployed position,
- fig. 6 is a similar view in a partially folded position,
- fig. 7 is an end view of this structure3 seen from the right in FIG. 5,
- fig. 8 is a view of this structure, seen from the top of FIG. 5,
- fig. 9 is a perspective view of a structure in accordance with the invention, with fully deployed solar panels,
- fig. 10 is a perspective view of a part of this structure> in a partially deployed position,
- fig. 11 is a perspective view of the structure of FIGS. 9 and 10, in the fully folded position,
- fig. 12 is a schematic view of a mast-type structure corresponding to another embodiment, in the deployed position,
- fig. 13 is a similar schematic view of a mast-type structure corresponding to the production of the fSg. 12 in the deployed position.

 For all the design details which will not be shown, reference should be made to the structures usually known for joints, springs, solar panels, space antennas such as satellite dishes, etc., as well as to publications mentioned above.

 Fig. 1 shows an intermediate position of a base element 1 between the fully folded and fully deployed positions. This element 1 consists of two uniform parts 2 and 3 which are connected at points 6 and 7, each part being made up of rigid bars, bars 10 to 13 for part 2 and bars 14 to 17 for part 3, by example made of a fiber-reinforced plastic as known per se, these bars ending in hinge joints 4 to 9. The articulation point 6 is carried by four bars 10, 11, 14 and 15, while the point 7 is carried by four bars 12, 13, 16 and 17. The movement that the basic element can take takes place in the plane of the drawing. Given that the bars 11 and 12, and 15 and 16, which overlap must be able to pass freely one before the other during the folding and deployment of the structure, the bar 11 is preferably made up of two parallel bars and the bar 12 moves between them. For a symmetrical construction of the platform, the bar 16 is also preferably made up of two bars and the bar 13 moves between them. Increasing the distance between points of articulation 4 and 5 produces an increase of the same extent in the distance existing between 8 and 9, while the distance between 6 and 7 is reduced. points 4 and 5, or 8 and 9, the basic bending 1 passes to an extreme deployed position, for example that or the bars 10 and 14 come to be in alignment with each other, which is then also the case for 13 and 17 (fig. 2). 4, on which we can see, in the direction of the imaginary line connecting the points 6 and 7s, a certain number of basic elements 1 of FIGS. 1 and 2, shows that the joints 4 and 5, and also 8 and 9 are connected to the corresponding joints of identical base elements 1 so as to form equilateral polygons which together constitute the structure> for example a load-bearing face for the platform -form of an antenna. If the equilateral polygons formed are triangles, a maximum of six basic elements can be connected to each junction point 4, 5 or 8, 9, each of these points being constituted by two points of joint located one below the other when looking at the figure.

 A structure of equilateral triangles is statically determined in the plane of FIG. 4 with regard to articulation movements in this plane. This aptitude for static determination remains if a certain number of polygons are made in the form of quadrilaterals (diamonds) as seen in 18 in FIG. 4.

One can also use inside the structure one or more quadrilaterals or even polygons having a greater number of sides, while retaining said aptitude for static determination, this provided that they are suitably surrounded by triangles. in order to clearly define the angular position of each side of such a polygon.

 If, after deployment, a structure to be carried is fixed (for example a grid of the flat antenna umbrella type), which is sufficiently rigid in the plane of FIG. 4, at at least one point of articulation of all the elements 1 or of a relatively large number thereof, and this on the same side of the structure (above or below in FIGS.

 1-3), said aptitude for static determination can be presented by this structure to be worn, and it is then possible, if desired, to use, throughout the structure or everywhere of the elements 1 are thus fixed to it, quadrilaterals or polygons with a larger number of sides which do not need, in themselves and together to be statically determined, if we look in the plane of fig. 4.

Only one which carries the structure, for example a satellite, can come into contact with this structure, for example at 19. With a view to folding back and deployment, external forces can be exerted at this point, coming for example from such a satellite, in order to force the points of articulation 4 and 5 located at this location to approach or move away from one another to achieve this folding or unfolding, but it is advisable to take specific arrangements at this location to avoid rotation of this structure with respect to such a satellite or the like in the plane of FIG. 4.It is in many cases pre maple to exert such forces at several points, for example in 19, 20 and 21, possibly also according to a set of articulation points 4, 5 which are not directly connected to the satellite , for example by means of a target which runs from the satellite along or through the structure, up to this set of articulation points, and which can be unwound and wound up using a winch, or by means of a structure having its own motor placed locally between a set of articulation points 4, 5. Points 20 and 21 cannot make fixed connections on the satellite since the structure could not then However, they can be fixed points on this satellite, but then in such a way that the structure is first of all only connected in 19 and is not fixed in 20 and 21 only after deployment. With a view to folding and deploying, it is also possible to provide guide tracks, oriented from 20 and 21 to 19 and through which the joints 5 can, for example, slide during this folding and this deployment, leaving the joints 7, with the adjacent bars,
free to protrude below them. The broken lines of
fig. 4 schematically represent such guide tracks.
another solution to this effect, probably more practical, consists in pre-
see an extendable mast along the platform and on one or more
dimensions, but in any case looking at fig. 4 along
points 19 and 20. Such a mast is preferably designed in accordance with
same principle of the present invention, as will be described below
opposite figs. 5-10. Such a mat can also be connected to the struc
ture of fig. 4 at interposed articulation points, and it can
also present a link with point 21. We can then fold
and deploy this mat at the same time as the structure according to FIG. 4.

If there are springs in the structure which
push back in the direction of deployment, said external forces doi
wind then force it in the direction of folding, that is to say -as
shown in fig. 1 and 2- in the direction of movement of the points
of articulation 4 and 5 towards each other, and vice versa.

a fig. 2 illustrates different possibilities for
arrange the springs. For example, we can provide
springs 22 between cooperating articulation points 6 and 7, and / or
springs 23 between cooperating articulation points 8 and 9 (or 4 and
5). These springs can be springs working in tension or
to compression, with for example possibly, in the case of res
compression spells, a telescopic bar to prevent a
buckling. As examples we have represented the articulation point 5
as having a helical spring 25 wrapped around the hinge rod or sleeve located there, its radial ends 26
and 27 pressing against bars 13 and li. These springs can stress
cite the structure in the direction of the position deployed in the
which bars 11 and 13 form a smaller angle with each other
ble, but the spring ends 26 and 27 can also come into contact on the other sides of these bars in order to stress the construction.
tion towards folding.

Of course, the influence of the springs on the re
folding or deployment will depend on their position and resis
mechanical strength, and also the degree of folding or deployment which determines the force components which are transmitted by the spring. During deployment from the folded position, going beyond fig. 1, to the position of fig. 2, the articulation points 4, 5 and 8, 9 will first be placed strongly in the lateral direction, but with little vertical movement, while towards the end of the deployment this situation is reversed. fig. 1, springs like 22 will release in the bars 10, 11, 14, 15 weaker force components than in a position approaching that of FIG. 2, while in this fig. 2 these components of the elastic forces released are greater in the bars 11 and 15, etc. If the springs 22 and 23 are tension springs, the elastic force manifested through the spring 22 will be greater in the state folded back (folding more pushes than in fig. 1), while the elastic force manifesting itself through the spring 23 is actually greater in the deployed state (fig. 2). It is thus possible to provide springs which complement each other well in order to achieve a flexible and gentle deployment and deployment in cooperation with the means providing external forces and which can move the points of articulation 4 and 5 (for example in 19, 20 and 21) towards or away from each other. If desired, springs can also protrude between two non-cooperating articulation points, or even between articulation points of different elements 1.

 Fig. 3 indicates the shape that the deployed structure can take if one does not wish to make its working part planar, but to make it curved in a concave or convex shape. It is assumed here that points 5 and 9 are replaced by points 5 'and 9' as shown in fig. 1. The bars 10, 12, 14 and 16 then remain of equal lengths, the bars 11, 13, 15 and 17 on the other hand then being shorter than the corresponding bars shown in FIG. 1 in solid lines. During deployment, we then obtain for the structure a work surface with warping and which is concave or convex. We can of course, as for the other figures, use in the case of FIG. 3, either the upper face or the lower face, or even the two faces as active face (s) for carrying useful parts.

 The structure then becomes such that, when the bars 10 and 14 of all the elements are in line with one another, the bars 13 to 17 form a certain angle with each other.

 The external means which exert forces at points such as 19, 20, 21 of FIG. 4 in order to allow movement of the articulation points 4 and 5 (or 8 and 9) in the direction and away from one another, may include, for example, means making it possible to maintain one of these points and move the other towards or away from it, which can for example be done with threaded rods and nuts or with cables. In order to fix desired positions, for example for stably maintain the bars 10 and 14 in line with each other in the deployed position of Figs. 2, 3 and 4, one can for example fix the maximum distances of the outermost points of articulation 4, 5 and 8, 9 of all the elements or some of them to which external forces are not applied in sight folding or unfolding, breasts by means of cables which in this precise position are stretched and connect such cooperating points of articulation. It is also possible to fix in one or more elements sliding bars which are connected to a point of articulation and along which the cooperating point of articulation slides, more particularly between 4 and 5 or 8 and 9.

 The articulation points will normally be designed as supports in which, at various points, articulation points are incorporated between fork-shaped parts.

For articulation points 4, 5, 8 and 9, these can be discs, located in planes perpendicular to the line of connection with the cooperating articulation, and provided along their periphery with cavities in which rods of the joint receives the ends of bars or the like which converge there. When many bars or the like converge, these points of articulation may lie in different parallel planes, perpendicular to this connecting line.

 At points 6 and 7 or only four bars always converge, it is possible to fix such a load-bearing body on a bar, this body then having three forks with articulation rods> one for each of the other bars converging at this location , or else two forks, with one of these forks carrying itself a carried body having two forks. For double bars, there may always be two of these cavities or forks having articulation rods. Such articulation structures are usually known in many forms.

 We will now discuss the structure of Figs. 513 on a mast assembled according to the principle of the invention. It can have many characteristics in common with the structure of FIGS. 1-4 as described above, these characteristics are not all detailed below in a precise manner, as will be obvious to the specialist.

 There is provided, arranged on a supporting structure, for example a space satellite 28, a series of elements I in accordance with FIGS. 1 and 2 and in which the points of articulation 8 and 9 of each preceding element are combined with the points of articulation respectively 4 and 5 of a following element 1. Two elements are thus shown connected in series in FIGS. 5, 6 and 8, six elements are shown in FIG. 9, three elements in FIG. 10 and three elements in figs. 12 and 13. In reality, a considerably greater number can be expected than the two or three elements shown for reasons of clarity, all these elements being connected in series as shown in the drawings.

 The articulation structures are preferably each made using continuous articulation rods 4, 6, 8, 34, 35 around which engage the articulation sleeves of the bars as shown in FIGS. 7 and 8 , each bar of each element being able to consist of two parallel bars located at a certain distance> while FIG. 8 shows how each bar looks as part of a flat frame, with a diagonal bar disposed between any pair of two parallel bars. This is shown in detail in fig. 8 for two bars 10 and two bars 14.

Each bar 10 corresponds to an analog bar 10 'situated at the opposite end of the same articulation rods 4, 6, 8, and this is also true for the other bars for which this is not shown, insofar as this provision is applicable. A slash
10 "rigidly connected to the bars 10 and 10 'stiffens such a flat sash. This is shown for two bars 14, 14' and 14". As can be seen in fig. 8, the bars which thus form part of the chassis frames can be identical to each other and their articulation sleeves can be stored side by side on the various articulation fabrics in such a way that the elements considered are always Slightly offset.

 The same arrangement is also possible for through bars 11, 12, 15, 16, but these should always be able to pass freely one before the other during the folding and unfolding of the structure, which limits the possibilities of bridging.

 All the articulations existing between the elements only allow a pivoting of these in the plane of the drawing of FIGS. 3 and 4. It is possible to have springs in all the articulations, for example helical springs situated around the articulation rods and having ends in sm'flie of elastic metallic wire which lean against the adjacent elements, in such a way that they lean on these elements in the direction of the deployed position shown in the drawing, thus allowing a reduction in the angle existing between each of two adjacent elements, but reacting against that - this in an elastic manner.

 In fig. 6, these springs are only shown diagrammatically (41) at two points of articulation 7 and 9. Near each point of mutual articulation, projecting abutment arms may be arranged on each element, these arms limiting by their stop the angular position of only one adjacent, against the a tion tion of said springs and coming to engage behind them, which limits for example this position to the deployed position shown in the drawing, and so as a variant to allow a zig zag folding. Such abutment arms are shown diagrammatically at 31 and 32. As will be described below, they can however be omitted in many cases.

 The outermost bars 14 and 17 are connected to each other at their outermost ends by bars 36 and 38 which are hingedly connected at 34 and 35 to these bars and are also hingedly connected. 'to each other at 37. Springs (not shown) provided in the articulation points of these bars 36 and 38 support the latter in an elastic manner in the direction of the position shown in the drawing, and it can here also be provided stops similar to stops 31 and 32 in order to limit the maximum angular rotation of the bars 36 and 38 relative to each other and relative to said bars 14 and 17. Bars 36 and 38, of course also in duplicate (for example 36, 36 'and 38, 38' in fig. 7) and possibly with a bracing design (not shown between the parallel parts, function as a toggle joint. a cable is provided 39 which cooperates with the jointed articulation rod lle 37 and which runs along the center line of the structure up to a winch drum 40 or another winding and unwinding element, using if necessary interposed deflection or guide rollers, so that this winch drum can be placed at any desired point, for example in or on the satellite.

 Fig. 6 shows how this structure can be folded. The winch 40 is used to haul the cable 39 inside, which pulls the articulation rod 37 to the left, so that the bars 36 and 38 extend first, after which the hinge rod 37 is pulled through the neutral line. The bars 14 to 17 are capable of elastically following the very slight increase which therefore occurs for the distance existing between 34 and 35. The further shortening of the cable 39 then causes the entire structure to fold up passing through the intermediate position of fig. 6, until a stack of elements is folded against the articulation structure 4, 5, with the possibility of retaining these stacks by means of holding and locking means which are not shown. During this folding, the articulation point 4 moves in the direction of the articulation point 5 to the same degree as the other articulation points 8, 9 move towards each other.

 By detaching these holding or locking means with respect to the folded batteries of elements and by gently letting the cable 39 slip, these batteries will be unfolded using the incorporated springs, passing through the position of FIG. 6 and up to that of FIG. 5.

 For reasons of clarity, part of the crossbars are shown interrupted or only partially in FIGS. 6, 7 and 8.

 The toggle joint structure 36 to 38 could also be arranged between opposite articulation points other than the last two located at 34 and 35, and more than one of these structures may also be provided. location along the length of the mast. Since the structure described having said springs tends to deploy, this deployment and the maintenance in the deployed position will be possible even in the case of faults, for example a cable burn 39 when the winch 40 is not operated properly. In addition, if defects appear in both the deployment and in the folding, an additional winch can be placed on the cable 39 near one or the other end of the structure.

 One can also arrange the stops 31 and 32 in such a way that, in the most deployed position, there is always an angle between the outer bars, as in FIG. 6, so that, by letting the cable 39 slip under the influence of the incorporated springs, the bars 36 and 38 adopt the position of FIG. 5 these bars 36 and 38 must however be shorter in order to be able to adopt the alignment position with each other. The resulting advantage and possible application will be described in more detail with reference to FIG. 10.

 As shown in 4 'in fig. 5, the articulation point 4 can, in the deployed position of the structure, be displaced to a certain extent relative to the position that it would naturally adopt, this in order to maintain a desired pre-stress in the structure. For this purpose, one can place an end stop for the movement of the articulation point 4 towards the outside while moving away from the point 5, in such a way that the left end of the bar 10 cannot reach this position which is naturally assigned to it, but on the other hand has an extreme position as represented by a dashed line. It is also possible, using active means of displacement, to position this point of articulation some little further away from the point of articulation 5 than is the naturally planned position, for the same purpose. In common with the stops 31, 32 and the springs 41, the prestress in the deployed structure is determined using such means. Deployment and folding can also be entirely directed by moving the articulation point 4 using such active means of displacement, by abandoning even if desired the articulation structure with ge nouillere 36-38 and by abandoning also possibly the springs such as 22. The articulation point 4 can slide in the slot 29.

 If the toggle joint 36-38 is abandoned, it is also possible, by means of such forced displacement of the articulation point 4 even further from the articulation point 5 than in FIG. 5, to fold this structure "in the other direction" relative to FIG. 6 and to maintain it in any desired intermediate position, which may be desirable for (the modification of) the most ideal position of the solar panels for example arranged on the elements. The bars 10 and 13 then extend in a convergent manner from the points of articulation 4 and 5, at the point of diverging as in FIG. 5, etc ...

 Fig. 9 shows in perspective such a structure in the fully deployed position. Solar panels 44 are arranged along each side of a part of the elements of the series, for example by connecting them to bars 13, 17. FIG. 10 shows part of this structure in a partially deployed position, part of a solar panel 44 extending towards the front being shown torn off.

 Fig. 11 represents the whole assembly folded up.

The solar panels have orifices 45 in order to allow the centering of their assembly folded over pins 43 located on the fixed structure 28 and each of which may have means for maintaining the assembly together. We see at 42 the articulation structures 4, 5, etc., as well as the means comprising the winch drum 40 and used to maneuver the cable 39 (here two parallel cables).

 In this case, the solar panels 44 considered are arranged on the second, fifth, sixth, ninth and tenth bars, etc. of the series of external bars 13, 17 which are connected in series, in counting from the fixed structure 28, and in a plane parallel to the plane of movement of the elements they are each of a length equal to;) resqile twice the length of each element or bar. One could also fix these panels, having the same length, for example on the second, the qtstrième and the sixth bars, etc ... of the series of bars which are in connection er. serine, so that they are always parallel to each other and all absorb solar energy to the same degree. Thanks to a modification of the degree of deployment of the mat, it is then possible to direct them as perpendicularly as possible towards the sun's rays.

 It could also be provided that the entire structure of the mast type is rotatably mounted around its axis on the support structure located at 28, so that, without adjusting the position of this support structure, for example of the satellite, we can always direct the solar panels optimally in relation to the sun.

 Figs. 12 and 13 show a mast type structure, according to the invention, in which the bars 10 and 14 are Ae equal length, but longer aue the elements (or bars) 13, 17 which are also equal in length between them. The crossing bars 11, 12, 15, 16 are here also of different lengths: longer bars 11, 15 and shorter bars 12, 16. In this way, a mast is obtained which, when deployed, adopts a position which is curved in the direction of the side of the shorter bars 13,17, that is to say which is of a folded form in a stepped manner, against represented in the drawing. This can be very useful, for example to carry a satellite dish. In other respects, the structure can be designed in all its details in exactly the same way as the embodiment described for FIGS. 5 and 6. If one or more of the cables such as 39 are used for folding, they can be guided over rollers located on articulation rods 5, 7 and / or 9, in order to avoid damage. With a greater or lesser degree of deployment, the angular position of the free end of the mast is also changed, which is particularly advantageous for the purposes of angular adjustment, for example of a satellite dish or of solar panels.

 Fig. 12 shows this structure in the nartially deployed position and FIG. 13 in the fully deployed position.

 Thanks to slight modifications in the lengths of the various barrels, it is possible to obtain deviations from the deployed position shown in the drawings, for example with the articulation points 9 in FIG. 13 arranged in such a way that the adjacent bars 13 and 17 are aligned with each other, or even in such a way that the points of articulation 9 are located more inwards so as to form a bend inward, rather than outward, between adjacent bars.

 In the case of all the embodiments, it is in principle possible to provide that the through bars 11 12, 15, 16 come into articulated contact with each other not at the ends of these bars, as shown, but at a certain distance from these ends, although, to receive the joints, the structures shown are preferable. Solar panels or antenna faces could also be connected to such cross bars. In the embodiments of FIGS. 12 and 13, this has the advantage that they can be placed in a large number of different directions, even for the same position and the same degree of deployment of the mast, while these bars have a high torsional rigidity.

 The elements may also have a different distribution of lengths, for example being alternately longer and shorter on each side of the series of elements.

 it will thus be clear that the elements 1 according to the invention can be used for many different purposes and that they can be combined with other structures which they must or must carry, and with any number of elements of the same type in one or more directions, while obtaining a simple system with high reliability, excellent performance in mechanical strength and stiffness in the deployed state, high design flexibility, low cost of production due to a large number of identical or almost identical elements, and finally simple ground tests.

Claims (14)

 1. Spatial structure foldable inwards and outwards, of the type comprising a number of bars or the like (10 to 17) essentially rigid and connected in an articulated manner, with springs (22, 23) cooperating with at least part of the articulation points (4 9) connecting the bars or the like and pushing them back in the direction of folding and unfolding, in the direction of folding or unfolding, characterized in that said structure comprises a certain number of elements (1), each forms two sets (2, 3) of four bars or the like (10 to 13, 14 to 17) and six points of articulation (4 to 9) forming three mutually cooperating sets of two points of articulation (4-5, 6-7, 8-9), two (4-5) at one end when looking in the direction of folding and deployment, two (8-9) at the other end, and two (6-7) between them, while the two articulated points of each set are each movable transversely in said direction towards and away t from each other, two bars or the like (10-13, 14-17) of each set extending between adjacent articulation points each of which belongs to a different set (4-5, 6- 7, 8-9) of articulation points, on one side of the center line of the element, which extends in the direction of folding and deployment, the two other bars or the like (11-12, 15-16 ) of each set extending each, between two bars or the like of the same set, of the two ribs of said center line, these two other bars or the like (11-12, 15-16) being connected in a hinged manner to said bars or analogs (lt-13, 14-17) on one side of said center line so as to cross each other in a mobile manner, and in that a number of such elements (1) are mutually connected articulated by sets of two points of articulation (4-5, 8-9) located at one end of each element (1).  2. Structure according to claim 1, characterized in that it comprises means (39) for moving the bars in a direction opposite to the direction in which the springs (22, 23) push the bars or the like.  3. Structure according to claim 2, characterized in that said means (39) cooperate with a set of cooperating articulation points (34, 35) so as to modify their distance.  4. Structure according to any one of claims 1 to 3, characterized in that a certain number of elements are connected together by means of such end articulation points so as to form, in a plane which is transverse to the planes of the elements (1), equilateral polygons.  5. Structure according to claim 4, characterized in that the elements (1) are arranged, at least for the most part, according to equilateral triangles.  6. Structure according to any one of Claims 1 to 5, characterized in that a certain number of elements (1} are connected to each other in a series connection, two points of articulation (8, 9) located at one end of an element (I) being joined at two points of articulation (4, 5) located at the other er, tremite of another element (1).  7. Structure according to claim 6, characterized in that, between two cooperating bars or articulation points located on opposite sides of an element (1), when looking in the transverse direction relative to the midline of the element, two bars (36, 38) arranged in a series connection are connected with an articulated hinge so that they are adapted to articulate with respect to each other and to articulate each on the 'one of said bars or articulation points, said pair of bars with series connection together forming a knuckle joint or dead center protrusion mechanism, with means! 39) intended to cooperate with their common articulation point (37 ) in order to move it to allow folding when they are arranged on one side of their alignment position with each other, and prevent their folding when they are arranged on the other side of this position alignment with each other.  8. Structure according to claim 7, characterized in that a flexible traction element (39) stétend from 'said point (37) of mutual articulation between the two bars (36, 38) to a supporting structure ( 28), in order to move said point (37; against the action of the springs (22, 23), in the direction of this support structure (28) and in the direction of the folded position of said bars (36, 38 ), which makes it possible to fold back, and for additional displacement in the direction of the support structure (28) in order to fold said deployed structure against the action of the springs (22, 23).  9. Structure according to any one of claims 6 to 8, characterized in that the transveXsales bars engage in the points of articulation of the four bars considered 10, 13, 14, 17) of the elements (1) on the same side of the direction of folding and deployment looking in the transverse direction with respect to it so as to articulate around the same articulation rod.  10. Structure according to any one of claims 6 to 9, characterized in that a number of bars comprise two parallel bars (10-10 ', 14-14') with a bracing (10 ", 14") between they.  11. Structure according to any one of claims 1 to 10, characterized in that at least some of the elements (1) carry solar panels (44).  12. Structure according to claim 11 when it depends on claim 6, characterized in that said solar panels are arranged on bars or the like (13, 17) of only a single series of a number of elements (1 ) and are about twice the length of said bars (13, 17) and protrude therefrom for about half the length on one side.  13. Structure according to claim il ouol2, ------------ characterized in that said solar panels (44) protrude on one or the other side of said elements (1), looking at right angles to the direction of deployment and at right angles to the plane in which the points of articulation move between the elements.  14. Structure according to any one of claims 1 to 13, characterized in that the bars or the like (13, 77) - located on a side of said center line of at least part of the elements (1) are shorter as bars or the like (10> 14) - located on the other side of the same elements, so that, in its deployed position, the structure is concave or convex.