OPTIMIZED INFLATABLE STRUCTURE

Abstract

An inflatable structure comprising a vertical inflatable mast (8) with captive air, and at least one elongated inflatable beam (22) with captive air extending beyond said vertical mast (8) and having a support point at a first end (24) located near the mast (8). According to the invention, the structure includes at least one guy wire (30, 31, 32) connected on one side to a first anchor point (A1, A2) of said guy wire to said mast (8) and on the other side to a second anchor point (B1, B2, B3) of said guy wire to the inflatable beam (22) between the first (24) and second ends (26) of the inflatable beam (22). Figure for the abbreviation: Fig. 2

Description

Title of the invention: OPTIMIZED INFLATABLE STRUCTURE

[0001] The present invention relates to the field of inflatable structures, more particularly of the type comprising air chambers or inflatable tubes forming part of the framework of enclosures, shelters or tents when covered with a canvas, or of any structure comprising an assembly of at least two inflatable tubes.

[0002] In this field, enclosures are known to comprise a frame made up of an assembly of interconnected inflatable tubes equipped with an access point for an inflation fluid, such as an inflation valve. After inflation, the tubes provide rigidity to the frame. These structures are generally self-supporting; once inflated, they maintain their shape and support roofs or doors, in the case of enclosures or shelters, or they support other elements belonging to the structure of which they are a part. When deflated, these structures are generally stored in compact devices, particularly for transport. Among the known folding methods, those resembling the folding of a sheet or a parachute are known, where these folds are manual and require considerable manpower.

[0003] In the case of inflatable structures which have large vertical dimensions such as a parasol, an umbrella or a totem, inflatable structures which are designed so that they can be completely deflated for storage and folded position while presenting a large span around a central mast in their unfolded position, the mechanical strength of the structure supported by a central mast is paramount.

[0004] More specifically, the beams of the inflatable structure are made up of inflatable tubes, each tube having an air chamber whose walls are made of a flexible material, and a shape of revolution, most often cylindrical. However, the use of cylindrical inflatable tubes with flexible skins to create mechanical beams is limited in their bending and compression strength by the allowable stress in the skin. Thus, in order for the inflatable tubes to withstand the loads, they must be prestressed, i.e., inflated to an internal pressure that allows their flexible skin to withstand the external load.

[0005] We also wish to reduce the bending loads to which such a beam is subjected.

[0006] Furthermore, when the central mast is itself inflatable, it must be designed to withstand the mechanical stresses experienced by the inflatable structure it supports, whether under normal load (for example, compression and buckling stresses in the absence of parasitic phenomena, such as those due to weather) or when Weather conditions (wind, rain, hail) induce additional mechanical stresses which, most of the time, are borne by the central mast.

[0007] The objective of the invention is to remedy at least in part these drawbacks and to propose an optimized inflatable structure, made in such a way as to resist the mechanical stresses due to the nominal load, as well as the point loads that may occur during its use.

[0008] This objective is achieved by the invention which proposes an inflatable structure comprising a vertical inflatable mast with captive air, at least one elongated inflatable beam with captive air extending in projection from said vertical mast having a support point at a first end located in the vicinity of the mast, characterized in that the structure comprises at least one guy wire connected on the one hand to a first anchorage point of said guy wire to said mast and on the other hand to a second anchorage point of said guy wire to the inflatable beam between the first and second ends of the inflatable beam.

[0009] By stay, we mean a wire element, such as a rope, cable, or strap, sufficiently strong to provide support for the beam from the mast. In other words, the invention proposes an inflatable structure of the type comprising an inflatable beam suspended from a vertical inflatable mast, the beam forming a certain angle with the mast. In a preferred embodiment of the invention, the inflatable beam extends transversely from the mast. The assembly thus created allows the beam to work only in compression when a load is applied vertically downwards, the stay working in tension to resist the forces resulting from the vector decomposition. Such a load can be the self-weight of the beam and the elements it supports, or even additional point loads, such as those resulting from inclement weather (rain, snow, hail, etc.).) or birds landing on the structure when it is used outside a building.

[0010] In one embodiment of the invention, said stay connects a first anchor point of said stay to the mast to a second anchor point of said stay to the beam, the second anchor point of said stay to the beam being located at a distance ranging from 0.7L to 0.8L, preferably equal to 0.75L, L being the total length of said beam. Thus, it was found during laboratory tests that, in this configuration, the curve of the moments experienced by the loaded beam was well balanced.

[0011] The inflatable structure may include at least one second stay connecting a first anchor point of the second stay to the mast to a second anchor point of the second stay to the beam located at a distance of 0.4L to 0.6L, preferably 0.5L, where L is the total length of said beam. By connecting the beam to the mast with a second stay, the load is better distributed in the stays, and a second load attachment point is provided under the beam.

[0012] In a preferred embodiment of the invention, said beam can be mobile between a compacted position which is close to the mast and a deployed position when it extends out transversely to the mast and said stay can be a wire element connected to traction means.

[0013] The structure may include at least one third stay connecting a first anchor point of the third stay located below the first anchor point of said stay and / or of the second stay to the mast to a second anchor point of the third stay to the beam, the second anchor point of the third stay to the beam being located at a distance of 0.2L to 0.3L, preferably 0.28L, where L is the total length of said beam. This additional stay thus allows for better distribution of the loads on the mast to prevent buckling and provides a third load attachment point below the beam.

[0014] The inflatable structure may include at least one tie rod connected on one side to a third anchor point of said tie rod to the mast and on the other side to a fourth anchor point of said tie rod to the beam. Such a tie rod allows the structure to resist reverse forces caused, for example, when wind rushes under the inflatable beam.

[0015] In one embodiment of the invention, the inflatable structure may include three tie rods, each connecting a third anchor point of each tie rod to the mast to three fourth anchor points of each tie rod to the beam.

[0016] Preferably, said fourth anchor points are diametrically opposite said second anchor points.

[0017] The mast and said beam may each comprise an outer sheath, and a harness may be mounted on the outer sheath of the beam and / or the mast, said harness comprising:

[0018] - at least one belt radially surrounding the outer casing,

[0019] - a strap having first and second longitudinal strands extending from of said belt along the outer sheath and arranged on either side of said outer sheath, and of a connecting strand linking the first and second longitudinal strands and in contact with one of the axial ends of the outer sheath, and

[0020] - at least one attachment device for the mast and / or beam of said elongated element mounted on said belt and / or on said strap.

[0021] Thus, when a stay is attached to said attachment device of the harness and exerts a tensile force on said attachment device, the tensile force is distributed between an axial force along the strap and a radial force along said belt, thus reducing the risk of damage to the beam and / or the mast.

[0022] The inflatable structure may comprise a plurality of air-inflatable beams captive structures arranged around the mast. This allows for a large-scale inflatable structure that is both efficient and lightweight.

[0023] The inflatable structure may comprise at least three, in particular six, regularly spaced, captive-air inflatable beams extending transversely from said vertical mast, the inflatable structure further comprising at least one fabric fixed between each pair of successive captive-air inflatable beams. This makes it possible to obtain a protective inflatable structure, such as a parasol or umbrella.

[0024] The invention will be better understood from the following description, which is based on the following figures: [Fig. 1] being a realistic perspective view of an inflatable structure according to the invention; [Fig.2] is a schematic side view of part of the inflatable structure of [Fig.1]; [Fig.3] is a schematic perspective view of a detail of the fabrication of a beam from [Fig.2].

[0025] In the various figures, identical or similar elements bear the same reference. Their description is therefore not systematically repeated.

[0026] Figure 1 shows an example of an inflatable structure 2 of the invention, which is a structure capable of providing sun protection, like a parasol, over a fairly large area. The structure is capable of being inflated and deflated using means contained in a housing 7. The inflatable structure is composed, in this case, of a central vertical mast 8 and several horizontal members 14 that support a canopy 10. In the illustrated embodiment, the inflatable structure 2 comprises six members 14 that support a hexagonal canopy 10. Hexagonal canopies have the advantage of allowing several inflatable sun protection structures 2 to be placed side by side in a hexagonal pattern to obtain sun protection over a larger area. Alternatively, the canopy 10 can have other shapes, for example, circular, oval, square, or rectangular.The members 14 have for this purpose six substantially horizontal arms regularly distributed around the circumference of the mast 8, two adjacent arms supporting a panel of fabric 16 which is an openwork fabric designed to provide shade while allowing the wind to pass through. The six panels of fabric 16 side-by-side form the canopy 10. In a variant, when it is desired to use the inflatable structure 2 as weather protection, the fabric 16 can be a waterproof fabric.

[0027] The inflatable structure 2 of the invention comprises a central cylindrical tubular mast 8 with captive air, the longitudinal axis 3 of the mast 8 extending vertically, and a plurality of elongated, captive-air inflatable elements 18 spaced regularly in the circumferential direction, here numbering six, each in contact with the two elongated elements 18 that are directly adjacent to it in the circumferential direction. Each elongated element 18 comprises a first tubular segment 20 and a second tubular segment, referred to as a beam 22 in what follows, connected to each other by a folding segment 24. The first tubular segments 20 of the elongated elements 18 are, in the illustrated example, cylinders arranged with their longitudinal axes parallel to the axis 3 of the mast 8. The second tubular segments or beams 22 may have the same or a different cross-section as the first two, and they extend radially around the mast 8.

[0028] The casing 7 contains the inflatable structure in its folded state and includes means for inflating / deflating the structure. The dimensions of the casing 7 are sufficiently large to accommodate the inflatable structure 2 in its deflated and folded state, and it can be completely closed for storage or transport. The inflatable structure 2 also includes a base 100 for stabilizing it on the ground in its position. The stabilization means consist of the ballast weight of the entire structure and casing. The base 100 of the structure includes means for movement, for example, several wheels 70 and a trailer hitch (not shown), so that the casing 7 can be towed by a motorized vehicle, its dimensions being compatible with the dimensions of authorized trailers.In the deployed position, the structure's base provides ballast and stability on the ground, thanks to its own weight and several stabilizing arms 80 projecting transversely from the casing 7, five stabilizing arms 80 being shown in the example in [Fig. 1]. The stabilizing arms can serve as a bench and are made removable for transport.

[0029] The invention will be better explained on the basis of a simplified representation of a part of the inflatable structure 2, as illustrated in [Fig.2] in order to facilitate understanding.

[0030] According to the invention, the beam 22 is arranged so as to present a fixed support point at a first end, materialized in this example by the folding segment 24, supported by the first tubular elements 20 which are themselves supported on the base 100 of the structure. The beam 22 is suspended at its second end 26, opposite the first end 24, by being held by at least one guy wire 30, 31, 32 connected on the one hand to a first anchor point A1, A2 of the guy wire to the mast 8 and on the other hand to a second anchor point B1, B2, B3 of the guy wire to the inflatable beam 22.

[0031] The load supported by beam 22 is represented by the forces FRI, FR2, FR3, FR4 in [Fig. 2]. These loads are related to internal loads, for example the self-weight of the structure of which beam 22 is a part, as well as external loads such as snow, rain, hail, etc. When they are downward (directed from top to bottom) in the direction of beam 22), these loads are taken up by the stays of the invention, stays which work in tension and the beam itself which works mainly in compression thanks to the transfer of force, in particular via a harness of the type described below.

[0032] More specifically, a first stay 30 is fixed on one side to a first anchor point A1 of the stay on the mast 8, in this example located at the top 8' of the mast 8, and on the other side to a second anchor point B1 of the stay on the beam 22, the second anchor point B1 being located at a distance between 0.7 and 0.8L, preferably equal to 0.75L, L being the total length of said beam 22. Thus, by positioning a first stay in this way, the curve of the forces experienced by a uniformly distributed load on the beam is balanced, without the need to support the second end 26 of the beam 22 by an additional stay. The beam 22 held by the stay 30 then deflects very little.

[0033] The beam 22 is also held by a second stay 31 connecting a first anchor point Al of the stay to the mast 8, point Al located in this example at the top 8' of the mast 8, to a second anchor point B2 of the stay to the beam 22 located at a distance equal to approximately, preferably equal to 0.5L, L being the total length of said beam 22. This second stay has the particularity of being mounted fixed at one of its ends on the beam 22, its free end being connected to a winch (not shown) so as to be able to exert a pull on the beam 22 when the winch is rotated. We thus manage to change the angular position of the beam 22 relative to the mast 8, the beam 22 being able to pass, thanks to the stay 31, from a first deployed position when it extends transversely relative to the mast 8, to a compacted position, when it extends along the mast 8 by turning around the folding segment 24.Of course, any other angular position between these two limit positions is possible by appropriately rotating the winch around which the free end of the stay 31 is wound, and then holding this position fixed. In a variant of the invention, a stay connecting another point of the beam 22 to the mast 8 could be used to raise the beam 22.

[0034] The structure is further equipped with a third stay 32 which connects, in a fixed manner, a first anchor point A2 of the third stay to the mast 8, point A2 being located below the anchor point A1, to a second anchor point B3 of the third stay to the beam 22, the second anchor point B3 being located at a distance between 0.2 and 0.3L, preferably equal to 0.28L, L being the total length of said beam 22. A third stay 32 thus arranged prevents buckling of the mast 8 in the event of high stress on the structure 2. If A0 is considered to be the support point of the beam 22, point A2 is located midway between the top 8' of the mast 8 and the support point A0 corresponding to the support of the beam 22 on the first tubular segment 20.

[0035] According to an advantageous aspect, the beam 22 of the inflatable structure 2 of the invention further comprises three tie rods 40, 41, 42 each connecting in a fixed manner a third anchor point A3, connecting each tie rod to the mast 8, to three fourth anchor points Cl, C2, C3 of each tie rod to the beam 22, said fourth anchor points being diametrically opposite said second anchor points Bl, B2, B3, understood to be at the same distance from the mast 8, but located on the underside of the beam 22.

[0036] Point A3 can be located on the mast 8, aligned with points A1 and A2, or it can be radially offset and supported by the base 1 of the mast 8. Indeed, in an advantageous embodiment of the invention, the mast 8 can be reinforced around its circumference by circumferential inflatable tubes, here formed by the first tubular segments 20, each first tubular segment 20 being in contact with its neighbor and with the mast 8. The contacts between the different segments and the mast are made possible, for example, by means of an external casing mounted tightly against the first tubular segments 20 over a large part of their length from their base. Such an assembly forms the base 1 of the mast 8.

[0037] The tie rods thus made make it possible to take up loads such as those coming from the wind which rushes in from below, forces which would push the beam 22 upwards, thus making the tie rods 40, 41, 42 work in tension.

[0038] The example illustrated in [Fig.2] shows a beam 22 held by three stays 30, 31, 32 and three tie rods 40, 41, 42, their number being able to vary according to the dimensions of the structure and the stresses it is subjected to, knowing that the more stays and tie rods there are, the better the stresses are distributed on the beam 22.

[0039] The beam 22 and the mast 8 are cylindrical, tubular, captive-air inflatable elements, each comprising an outer casing made of a fabric, for example DACRON®, and an inner air chamber made of a stretchable material, for example polyurethane. The inner air chambers form the framework of the beam 22 and the mast 8. The inner air chambers are connected to an inflation fluid inlet via an inflation valve (not shown).

[0040] According to another advantageous aspect of the invention, the outer sheath of the mast 8 and the beam 22 each comprise a harness 50 fixedly mounted on the outer sheath of the beam 22 and / or the mast 8. An example of such a harness 50 is shown in [Fig. 3], where the illustrated harness is mounted on the beam 22. The harness 50 comprises several straps 53a, 53b, 53c, 53d radially surrounding the outer sheath of the beam 22. A strap 55 having first and second longitudinal strands extends from the straps 53a, 53b, 53c, 53d along the outer sheath of the beam 22, the longitudinal strands 51, 52 being arranged on either side of said outer sheath. Connecting strand 54 links the first and second longitudinal strands 51,52 by being in contact with one of the axial ends 26 of the outer sheath of the beam 22. The harness thus made is provided with several attachment devices for a stay 30, 31, 32 to the beam 22.

[0041] The tie rods 40, 41, 42 can also be attached by means of a harness of this type to the beam 22.

[0042] The mast 8 may also include a harness 50 of this type for attaching the shrouds 30, 31, 32 and / or the stays 40, 41, 42.

[0043] The attachment members 57a, 57b, 57c, 57d can be, for example, metal rings.

[0044] The belt 53a, 53b, 53c, 53d can be made of an elastic material.

[0045] Thus, when a stay or a tie rod is attached to the harness attachment device 50 and exerts a tensile force on said attachment device, the tensile force is distributed between an axial force along the strap and a radial force along said belt, thus reducing the risk of deterioration of the outer casing of the beam 22 or that of the mast 8.

[0046] The stays can be fixed to the upper part of the beam and the tie rods to the lower part of the beam 22. In an alternative, the stays and tie rods can be fixed to the sides of the beam 22.

[0047] The invention was tested using an inflatable structure as shown in [Fig. 1]. The canopy 10 is approximately 17 m in diameter. The first tubular segments or beams 22 are erected approximately 3.5 m above the ground to avoid any interaction with passersby. The top of the mast 8 is approximately 10 m above the ground. The elongated elements 18 are approximately 12 m long. The cross-sections of the elongated elements 18 and the mast 8 are approximately 45 cm in diameter, and the captive air chambers of the elongated elements 18 are inflated to a pressure of 0.3 bar, while the internal chamber of the mast is inflated to a pressure of 0.5 bar.

[0048] With a structure thus dimensioned, point Al is located at the top of the mast, point A2 is located 4270 mm from the top 8', point A3 is 2270 mm from point A0. Points B3 and C3 are located 2000 mm from the first end 24 of the beam 22, points B2 and C2 are located 4500 mm and points Al and B1 are located 7000 mm from the end 24 of the beam 22.

[0049] The dimensioning was carried out so that the allowable compressive force on the beam 22 remains less than the prestress given by the inflation pressure and the acceptable tensile limit of the wall of its air chamber. Thus, if the inflation pressure of the beam is equal to 0.3 bar and the diameter of the beam is 45 cm, then the stress supported by the beam is F max = pi x 452 / 4 x 0.3 = 477 daN.

[0050] The stays are positioned as close as possible to the points of application of the forces To limit the effects of bending on the beam, the anchor points of the stays are placed at the points of application of the loads FRI, FR2, FR3, which represents an ideal positioning avoiding having a force FR4 which would cause the beam to work in bending.

[0051] Other variants and embodiments of the invention may be envisaged within the scope of the invention as claimed.

Claims

Claims

1. Inflatable structure comprising a vertical mast (8) inflatable with captive air, at least one elongated beam (22) inflatable with captive air extending projecting from said vertical mast (8) having a support point at a first end (24) located in the vicinity of the mast (8), characterized in that the structure comprises at least one guy (30, 31, 32) connected on the one hand to a first anchoring point (A1, A2) of said guy to said mast (8) and on the other hand to a second anchoring point (B1, B2, B3) of said guy to the inflatable beam (22) between first (24) and second ends (26) of the inflatable beam (22).

2. Structure according to the preceding claim, characterized in that said guy (30) connects a first anchoring point (A1) of said guy to the mast (8) to a second anchoring point (Bl) of said guy (30) to the beam (22), the second anchoring point (Bl) of said guy (30) to the beam (22) being located at a distance ranging from 0.7L to 0.8L, preferably equal to 0.75L, L being the total length of said beam (22).

3. Structure according to one of the preceding claims, characterized in that it comprises at least one second guy (31) connecting a first anchoring point (A1) of the second guy (31) to the mast (8) to a second anchoring point (B2) of the second guy (31) to the beam (22) located at a distance ranging from 0.4L to 0.6L, preferably equal to 0.5L, L being the total length of said beam (22).

4. Structure according to the preceding claim, characterized in that said beam (22) is movable between a collected position in which it is close to the mast (8) and a deployed position when it extends transversely to the mast (8), said stay (31) being a wire element connected to traction means.

5. Structure according to one of claims 2 to 4, characterized in that it comprises at least one third guy (32) which connects a first anchoring point (A2) of the third guy (32) located below the first anchoring point (A1) of said guy (30) and / or of the second guy (31) to the mast (8) to a second anchoring point (B3) of the third guy (32) to the beam (22), the second anchoring point (B3) of the third guy (32) to the beam (22) being located at a distance ranging from 0.2L to 0.3L, preferably equal to 0.28L, L being the total length of said beam (22).

6. Structure according to one of the preceding claims, characterized in that it comprises at least one tie rod (40, 41, 42) connected on the one hand to a third anchoring point (A3) of said tie rod (40, 41, 42) to the mast (8) and on the other hand to a fourth anchoring point (Cl, C2, C3) of said tie rod (40, 41, 42) to the beam (22).

7. Structure according to the preceding claim, characterized in that it comprises three tie rods (40, 41, 42) each connecting a third anchoring point (A3) of each tie rod (40, 41, 42) to the mast (8) to three fourth anchoring points (Cl, C2, C3) of each tie rod (40, 41, 42) to the beam.

8. Structure according to the preceding claim, characterized in that said fourth anchoring points (Cl, C2, C3) are diametrically opposite to said second anchoring points (Bl, B2, B3).

9. Structure according to one of the preceding claims, characterized in that the mast (8) and said beam (22) each comprise an outer casing and in that a harness (50) is mounted on the outer casing of the beam (22) and / or of the mast (8), said harness comprising: - at least one belt (53a, 53b, 53c, 53d) radially surrounding the outer casing, - a strap (55) provided with first and second longitudinal strands (51, 52) extending from said belt (53a, 53b, 53c, 53d) along the outer casing and being arranged on either side of said outer casing, and a connecting strand (54) connecting the first and second longitudinal strands (51, 52) and being in contact with one of the axial ends of the outer casing, and - at least one member for attaching (57a, 57b, 57c, 57d) a shroud (30, 31, 32) or a tie rod (40, 41, 42) to said mast (8) and / or to said beam (22) mounted on said belt (53a, 53b, 53c,53d) and / or on said strap (55).,

10. Inflatable structure according to one of the preceding claims, characterized in that it comprises a plurality of inflatable beams (22) with captive air arranged around the mast.

11. Inflatable structure according to the preceding claim, comprising at least three, in particular six, captive air inflatable beams (22) regularly spaced in the circumferential direction and projecting transversely relative to said vertical mast (8), the inflatable structure (2) further comprising at least one canvas (16) fixed between each pair of successive captive air inflatable beams (22).

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