Optimized inflatable structure

Abstract

An inflatable structure comprising an airtight vertical inflatable mast (8), wherein at least one airtight inflatable elongate beam (22) projects with respect to said vertical mast (8) and has a bearing point at a first end (24) located in the vicinity of the mast (8). According to the invention, the structure comprises at least one stay (30, 31, 32), one end of which is connected at a first anchor point (A1, A2) to the mast (8), and the other end of which is connected at a second anchor point (B1, B2, B3) to the inflatable beam (22) between first (24) and second ends (26) of said inflatable beam (22).

Description

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 it is covered with a canvas, or of any structure comprising an assembly of at least two inflatable tubes.

[0002] In this field, enclosures are known comprising a framework made by an assembly of inflatable tubes connected to each other and provided with access to an inflation fluid, such as an inflation valve. After inflation, the tubes ensure the stiffening of the framework. These structures are generally self-supporting; once inflated, they maintain their shape and support coverings 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 small-sized devices, particularly for transport. Among the known folding methods, we know those similar to the folding of a sheet or a parachute, where these folds are manual and require a lot of labor.

[0003] In the case of inflatable structures which have significant 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 having a large span around a central mast in their unfolded position, the mechanical strength of the structure supported by a central mast is essential.

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

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

[0006] Furthermore, when the central mast is itself inflatable, it must be made in such a way as to withstand the mechanical stresses undergone by the inflatable structure that it supports, either under normal load (for example, compressive and buckling stresses in the absence of parasitic phenomena, such as those due to the weather) or when the weather conditions (wind, rain, hail) induce additional mechanical stresses which, most of the time, are supported 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 which may occur during its use.

[0008] This objective is achieved by the invention which provides an inflatable structure comprising a captive air inflatable vertical mast, at least one captive air inflatable elongated beam extending in projection relative to 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 connected on the one hand to a first anchoring point of said guy to said mast and on the other hand to a second anchoring point of said guy to the inflatable beam between first and second ends of the inflatable beam, said beam being movable between a collected position in which it is close to the mast and a deployed position when it extends in projection transversely to the mast, said guy being a wire element connected to traction means.

[0009] By stay is meant a wire element, such as a rope, a cable, a strap sufficiently strong to ensure the support of the beam by the mast. In other words, the invention proposes an inflatable structure of the type comprising an inflatable beam understretched suspended from an inflatable vertical mast, the beam forming a certain angle with the mast. In a preferred variant of the invention, the inflatable beam extends transversely to the mast. The assembly thus produced allows the beam to work only in compression when a load is applied to it vertically downwards, the stay working in tension to take up the forces resulting from the decomposition vectorial. Such a load can be the self-weight of the beam and the elements it supports, or even additional loads from time to time, such as those from bad weather (rain, snow, hail, etc.) or birds landing on the structure when it is used outside a building. Such a guy wire therefore ensures the movement and support of the mobile beam in the positions it can take in relation to the mast.

[0010] In an alternative embodiment of the invention, said guy connects a first anchoring point of said guy to the mast to a second anchoring point of said guy to the beam, the second anchoring point of said guy 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 tests carried out in the laboratory that in this configuration, the curve of the moments undergone by the loaded beam was well balanced.

[0011] The inflatable structure may comprise at least one second guy connecting a first anchoring point of the second guy to the mast to a second anchoring point of the second guy to the beam located at a distance ranging from 0.4L to 0.6L, preferably equal to 0.5L, L being the total length of said beam. By connecting the beam to the mast using a second guy, it is possible to better distribute the load in the guys and provide a second load attachment point under the beam.

[0012] The structure may comprise at least one third guy which connects a first anchoring point of the third guy located below the first anchoring point of said guy and / or of the second guy to the mast to a second anchoring point of the third guy to the beam, the second anchoring point of the third guy to the beam 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. Thus, this additional guy makes it possible to better distribute the loads at the mast in order to avoid its buckling and to provide a third load attachment point under the beam.

[0013] The inflatable structure may comprise at least one tie rod connected on the one hand to a third anchoring point of said tie rod to the mast and on the other hand to a fourth anchoring point of said tie rod to the beam. Such a tie rod allows the structure to withstand forces reversed caused for example when the wind rushes under the inflatable beam.

[0014] In an alternative embodiment of the invention, the inflatable structure may comprise three tie rods each connecting a third anchoring point of each tie rod to the mast to three fourth anchoring points of each tie rod to the beam.

[0015] Preferably, said fourth anchoring points are diametrically opposite said second anchoring points.

[0016] The mast and said beam may each comprise an outer casing and a harness may be mounted on the outer casing of the beam and / or the mast, said harness comprising: - at least one belt radially surrounding the external envelope, - a strap provided with first and second longitudinal strands extending from said belt along the outer casing and being arranged on either side of said outer casing, and with a connecting strand connecting the first and second longitudinal strands and being in contact with one of the axial ends of the outer casing, and - at least one member for attaching the mast and / or the beam to said elongated element mounted on said belt and / or on said strap.

[0017] Thus, when a guy line is attached to said attachment member of the harness and exerts a tensile force on said attachment member, 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.

[0018] The inflatable structure may include a plurality of captive air inflatable beams arranged around the mast. This provides a large-scale inflatable structure that is both high-performance and lightweight.

[0019] The inflatable structure may comprise at least three, in particular six, captive air inflatable beams regularly spaced in the circumferential direction and extending transversely projecting from said vertical mast, the inflatable structure further comprising at least one canvas fixed between each pair of successive captive air inflatable beams. This makes it possible to obtain an inflatable protective structure, such as a parasol or an umbrella.

[0020] The invention will be better understood from the remainder of the description, which is based on the following figures: figure 1 being a realistic perspective view of an inflatable structure according to the invention; figure 2 is a schematic side view of a part of the inflatable structure of figure 1; figure 3 is a schematic perspective view of a detail of the construction of a beam of figure 2.

[0021] In the various figures, identical or similar elements bear the same reference. Their description is therefore not systematically repeated.

[0022] Figure 1 represents an example of an inflatable structure 2 of the invention which is a structure capable of providing sun protection, such as a parasol, over a fairly large area, the structure being capable of being inflated and deflated using means contained in a casing 7. The inflatable structure is composed in this case of a central vertical mast 8 and several horizontal members 14 which support a canopy 10. In the illustrated embodiment, the inflatable structure 2 comprises six members 14 which support a canopy 10 of hexagonal shape. The hexagonal canopies have the advantage of being able to juxtapose several inflatable sun protection structures 2 according to a hexagonal mesh in order to obtain sun protection over a larger area. Alternatively, the canopy 10 may have other shapes, for example circular, oval, square, rectangular.The members 14 comprise for this purpose six substantially horizontal arms regularly distributed around the circumference of the mast 8, two adjacent arms supporting a piece of fabric 16 which is an openwork fabric intended to provide shade, while allowing the wind to pass through. The six pieces of fabric 16 side by side form the canopy 10. In a variant, when it is desired to use the inflatable structure 2 as protection against bad weather, the fabric 16 can be a waterproof fabric.

[0023] 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 inflatable elongated elements 18 with captive air regularly spaced in the circumferential direction, here six in number and each in contact with the two elongated elements 18 which are directly adjacent to it in the circumferential direction. Each elongated element 18 comprises a first tubular segment 20 and a second tubular segment, called beam 22 in the following, connected together by a folding segment 24. The first tubular segments 20 of the elongated elements 18 are in the example illustrated cylinders arranged with their longitudinal axes parallel to the axis 3 of the mast 8. The second tubular segments or beams 22 may have a section identical to the first or different from them and they extend radially around the mast 8.

[0024] The casing 7 encloses the inflatable structure in the folded state and it comprises means for inflating / deflating the structure. The dimensions of the casing 7 are large enough to accommodate the inflatable structure 2 in the deflated and folded state and it can be completely closed when storing the structure or transporting it. The inflatable structure 2 also comprises a base 100 allowing it to be stabilized on the ground in the position in which it is located. The stabilizing means are the ballast weight of the entire structure and the casing. The base 100 of the structure comprises moving means, 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 deployment position of the structure, its base ensures its ballast and stabilization on the ground, thanks to its own weight and to several stabilizing arms 80 projecting transversely with respect to the casing 7, five stabilizing arms 80 being represented in the example of figure 1. The stabilizing arms can serve as a bench and are made removable for transport.

[0025] The invention will be better explained on the basis of a simplified representation of a part of the inflatable structure 2, as illustrated in Figure 2 in order to facilitate understanding.

[0026] According to the invention, the beam 22 is arranged so as to have a fixed support point at a first end materialized in this example by the folding segment 24, supported by the first tubular elements 20 bearing, themselves, on the base 100 of the structure. The beam 22 is suspended at its second end 26, opposite the first end 24, being held by at least one guy 30, 31, 32 connected on the one hand to a first anchoring point A1, A2 of the guy to the mast 8 and on the other hand to a second anchoring point B1, B2, B3 of the guy to the inflatable beam 22.

[0027] The load supported by the beam 22 is represented by the forces FR1, FR2, FR3, FR4 in Figure 2. These loads are linked to the internal loads, for example the dead weight of the structure of which the beam 22 is part, as well as to the external loads such as snow, rain, hail, etc. When they are descending (oriented from top to bottom in the direction of the beam 22), these loads are taken up by the stays of the invention, stays which work in traction and the beam itself which works mainly in compression thanks to the force transfer, in particular via a harness of the type described below.

[0028] More particularly, a first guy 30 is fixed on the one hand to a first anchoring point A1 of the guy to the mast 8, in this example located at the top 8' of the mast 8, and on the other hand to a second anchoring point B1 of the guy to the beam 22, the second anchoring 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 guy in this way, the curve of the forces undergone by a uniformly distributed load on the beam is balanced, without there being any need to support the second end 26 of the beam 22 by an additional guy. The beam 22 held by the guy 30 then flexes very little.

[0029] The beam 22 is also held by a second guy 31 connecting a first anchoring point A1 of the guy to the mast 8, point A1 located in this example at the top 8' of the mast 8, to a second anchoring point B2 of the guy 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 guy has the specific feature 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 traction on the beam 22 when the winch is rotated. This makes it possible to change the angular position of the beam 22 relative to the mast 8, the beam 22 being able to pass, thanks to the guy 31, from a first deployed position when it extends transversely relative to the mast 8, to a collected position, when it extends along the mast 8 by rotating around the folding segment 24. Of course, any other angular position between these two limit positions is possible, by appropriately rotating the winch on which the free end of the shroud 31 is wound, then maintaining this position fixed. In a variant of the invention, a shroud connecting another point of the beam 22 to the mast 8 could be used to raise the beam 22.

[0030] The structure is also provided with a third guy 32 which connects, in a fixed manner, a first anchoring point A2 of the third guy to the mast 8, the point A2 being located below the anchoring point A1, to a second anchoring point B3 of the third guy to the beam 22, the second anchoring point B3 being located at a distance of between 0.2 and 0.3L, preferably equal to 0.28L, L being the total length of said beam 22. A third guy 32 thus arranged makes it possible to prevent the mast 8 from buckling in the event of heavy loading of the structure 2. If AO is considered to be the support point of the beam 22, the point A2 is located midway between the top 8' of the mast 8 and the support point AO corresponding to the support of the beam 22 on the first tubular segment 20.

[0031] 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 fixedly connecting a third anchoring point A3, connecting each tie rod to the mast 8, to three fourth anchoring points C1, C2, C3 of each tie rod to the beam 22, said fourth anchoring points being diametrically opposite said second anchoring points B1, B2, B3, understood to be at the same distance from the mast 8, but located on the lower face of the beam 22.

[0032] The point A3 can be located on the mast 8 by being aligned with the points A1 and A2 or it can be radially offset by being supported by the base 1 of the mast 8. Indeed, in an advantageous embodiment of the invention, the mast 8 can be reinforced on 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 of the different segments and of the mast being made possible for example by means of an external envelope mounted tightly in contact with 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

[0033] The tie rods thus produced make it possible to take up loads such as those coming from the wind blowing in from below, forces which would push the beam 22 upwards, thus making the tie rods 40, 41, 42 work in tension.

[0034] The example illustrated in Figure 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 to which it is subjected, knowing that the more numerous the stays and tie rods there are, the better the forces are distributed on the beam 22.

[0035] The beam 22 and the mast 8 are captive air inflatable elements of cylindrical tubular shape each comprising an outer casing based on a fabric, for example DACRON® and an inner air chamber formed from an extensible 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 inlet for an inflation fluid via an inflation valve (not shown). In a variant, the outer casing of the mast 8 and the beam 22 can be made of an impregnated fabric impervious to the inflation fluid, which makes it possible to save on an inner air chamber.

[0036] According to another advantageous aspect of the invention, the outer casing of the mast 8 and the beam 22 each comprise a harness 50 fixedly mounted on the outer casing 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 belts 53a, 53b, 53c, 53d radially surrounding the outer casing of the beam 22. A strap 55 provided with first and second longitudinal strands extends from the belts 53a, 53b, 53c, 53d along the outer casing of the beam 22, the longitudinal strands 51, 52 being arranged on either side of said outer casing. A connecting strand 54 connects the first and second longitudinal strands 51, 52 while being in contact with one of the axial ends 26 of the external envelope of the beam 22. The harness thus produced is provided with several members for attaching a stay 30, 31, 32 to the beam 22.

[0037] The tie rods 40, 41, 42 can also be attached by means of a harness of this type to the beam 22.

[0038] The mast 8 may also include a harness 50 of this type for attaching the shrouds 30, 31, 32 and / or the tie rods 40, 41, 42.

[0039] The attachment members 57a, 57b, 57c, 57d may be, for example, metal rings.

[0040] The belt 53a, 53b, 53c, 53d may be made of an elastic material.

[0041] Thus, when a guy rope or a tie rod is attached to the attachment member of the harness 50 and exerts a tensile force on said attachment member, 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 external envelope of the beam 22 or that of the mast 8.

[0042] The stays may be attached to the upper portion of the beam and the tie rods to the lower portion of the beam 22. Alternatively, the stays and tie rods may be attached to the sides of the beam 22.

[0043] The invention was tested using an inflatable structure in accordance with Figure 1. The canopy 10 is approximately 17 m in diameter. The first tubular segments or beams 22 are erected approximately 3.5 m from the ground to avoid any interaction with passers-by. The end of the mast 8 culminates approximately 10 m from the ground. The elongated elements 18 are approximately 12 m long. The 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, the internal chamber of the mast being inflated to a pressure of 0.5 bar.

[0044] With a structure thus dimensioned, point A1 is located at the top of the mast, point A2 is located 4270 mm from the top 8', point A3 is located 2270 mm from point A0. Points B3 and C3 are located 2000 mm from the first end 24 of beam 22, points B2 and C2 are located 4500 mm and points A1 and B1 are located 7000 mm from the end 24 of beam 22.

[0045] The dimensioning was carried out in such a way that the compressive force admissible by the beam 22 remains lower than the prestress given by the inflation pressure and the tensile limit acceptable by 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 45cm then the stress supported by the beam is F max = pi x 45 2 / 4 x 0.3 = 477 daN.

[0046] The stays are positioned as close as possible to the points of application of the point forces to limit the bending effects of the beam. The anchor points of the stays are therefore placed at the right angles to the points of application of the loads FRI, FR2, FR3, which represents an ideal positioning avoiding having an FR4 force which would cause the beam to bend.

[0047] Other variations and embodiments of the invention may be contemplated 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), said beam (22) being movable between a collected position in which it is close to the mast (8) and a deployed position when it projects transversely to the mast (8), said guy (31) being a wire element connected to traction means.

2. Structure according to the preceding claim, characterized in that said stay (30) connects a first anchoring point (A1) of said stay to the mast (8) to a second anchoring point (Bl) of said stay (30) to the beam (22), the second anchoring point (Bl) of said stay (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 stay (31) connecting a first anchoring point (A1) of the second stay (31) to the mast (8) to a second anchoring point (B2) of the second stay (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 one of claims 2 to 3, 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).

5. 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).

6. 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.

7. 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).

8. Structure according to one of the preceding claims, characterized in that the mast (8) and said beam (22) each comprise an external envelope and in that a harness (50) is mounted on the external envelope of the beam (22) and / or of the mast (8), said harness comprising: - at least one belt (53a, 53b, 53c, 53d) radially surrounding the external envelope, - 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 with 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 attachment member (57a, 57b, 57c, 57d) of 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).

9. 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.

10. 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 extending 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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