optimized inflatable soft structure

Abstract

Inflatable structure comprising at least one flexible inflatable sealed chamber capable of being filled with an inflation fluid at a nominal pressure P, a flexible drain, the drain being permeable to the inflation fluid and capable of maintaining the circulation of the inflation fluid between its two fixed ends As and Bs of the structure, when a pressure greater than the nominal pressure P is applied to at least part of the structure such that the inflation fluid is prevented from circulating between the ends As and Bs of the chamber except by the drain. Abstract figure: figure 1

Description

Title of the invention: optimized inflatable flexible structure

[0001] The present invention relates to the field of inflatable objects or structures, more particularly of the type comprising at least one inflatable tube, such as buoys, mattresses, tubes and more particularly large inflatable structures, parts of the framework of enclosures, shelters or tents when covered with a canvas, or comprising one or more inflatable tubes used in the manufacture of furniture or floating objects.

[0002] In this field, inflatable structures are known comprising a frame comprising airtight inflatable tubes or, more generally, without any implied shape, airtight inflatable chambers most often contained in a structural envelope comprising a reinforcing fabric or merging with the structural envelope in the case of fabrics made airtight by impregnation with a airtight matrix. The inflatable chambers are most often provided with inflation valves which are a form of access but not necessarily or only, the structure being able to be maintained under pressure by being connected to a pump regulating a nominal pressure or working pressure proposed by the manufacturer of the structure, for example through a connection tube, the pump compensating for any losses of inflation fluid due to any imperfections in the sealing. After inflation, the airtight chambers ensure the shape and stiffening of the structure.

[0003] Some of these structures are self-supporting (FR2980341_Bl, FR3044958Al), once inflated they maintain their shape and support covers or doors, in the case of enclosures or shelters, or they support trays or other furniture elements, in the case of furniture, such as tables or inflatable seats.

[0004] These structures may include inflatable or non-inflatable appendages, fabrics, ropes, a whole set of varied elements that can interact with the structure and the inflatable chamber(s) and make knots around a part of the sealed chamber preventing easy inflation and deflation. Furthermore, even for simple tubes, it is possible to have uses including interactions with objects placed on the middle of the tube when deflated, preventing the inflation of a part of the tube, access to the sealed chamber of the fluid being, for a part of the tube, prevented by the object exerting pressure, the object exerting pressure being also able to be an inflatable structure, and in the same way, for deflation.

[0005] For example, one of the common problems with inflatable appendages is that during deployment of the structure or storage of the structure, the appendage twists by making several turns on itself at a point of flexibility. On a conventional structure, these twists can create sub-chambers that are watertight with respect to the remains of the inflatable structure and requires human intervention on a structure that has not finished inflating and is therefore potentially unstable and on which it is therefore difficult to intervene.

[0006] The inventors set themselves the objective of solving these problems inherent in flexible inflatable structures which, during their use, inflation or deflation, can create sub-cavities which are sealed against the inflation fluid, the inflation fluid then no longer being able to circulate between said sub-cavity and the rest of the structure, including preventing total or partial inflation or deflation of the structure.

[0007] This objective has been achieved, according to the invention, by an inflatable structure comprising: - at least one sealed inflatable flexible chamber capable of being filled with an inflation fluid at a nominal pressure P, by at least one access to the sealed chamber, the chamber having in its inflated state a section of smaller length Le, - a flexible drain, of a section S of greater length Ld, having at least two ends As and Bs fixed in the sealed chamber, - the drain being permeable to the inflation fluid and capable of maintaining the circulation of the inflation fluid between the two points As and Bs of the sealed chamber, when a pressure greater than the nominal pressure P is applied to at least a part of the structure so that the inflation fluid is prevented from circulating between the ends As and Bs of the sealed chamber except by the drain.

[0008] The invention therefore consists in providing a drain making it possible to continue to supply all or part of the sealed chamber located between the ends of the drain As and Bs, even if any object applies pressure between the ends of the drain As and Bs on all or part of the structure including the drain, pressure higher than the nominal pressure, preventing the circulation of the inflation fluid between the ends As and Bs of the drain in the inflation chamber outside the drain. This means that the drain remains permeable to the inflation fluid even when compressed to a pressure higher than the nominal or use pressure. Preferably the drain remains permeable to the inflation fluid even when compressed to a pressure equal to the burst pressure of the inflatable structure.The invention can be used in a wide range of pressure and for many uses, it is therefore difficult to quantify a priori the pressure resistance that the drain must have, this resistance is more linked to the objects likely to apply the pressure preventing the circulation of the inflation fluid in the structure except in the drain than to the operating pressure. To ensure operation of the drain in all circumstances where the structure is likely to be found, the drain must remain permeable to the inflation fluid even when compressed to a pressure equal to the rupture pressure of the inflatable structure, beyond this pressure, the structure will suffer a decline, either by loss of its sealing or by rupture of any reinforcing elements that it includes.

[0009] This invention solves a large part of the problems for the inflation of appendages which tend to twist on themselves for inflatable structures. It is sufficient to put a drain on either side of the place where the twist occurs which is most often the same. If the twist risks being positioned at any point of the chamber, it is sufficient to put the drain on the entire length of the sealed chamber from the access to the chamber to the point of the chamber furthest from it. In fact the drain makes it possible to multiply by two the torsional torque which the inflation fluid applies to the twist. Indeed, certain structures tending to twist, untwist themselves under the effect of inflation when the torque which the inflation fluid exerts on the inflatable structure is greater than the resistive torque which keeps the sealed chamber in the twisted position.In general this torque is linked to the mass of a part of the structure, in this case, or in the cases of a fold which can also prevent the circulation of the inflation fluid between the ends of the drain, the object applying a pressure higher than the nominal pressure is the sealed chamber itself, or the inflatable structure. When this torque is not sufficient, it is possible, to increase the torque, to increase the pressure at the risk of damaging the sealed chamber, or to multiply the torque by two by using a drain according to the invention without increasing the pressure and therefore without any risk for the chamber.

[0010] By flexible structure, it is meant that the sealed chamber being empty, certain points of the wall of the chamber in contact with the inflation fluid, which in the inflated state, are distant from each other by a non-zero distance, can be in contact in the deflated state. The sealed chamber consists essentially of a membrane, single-layer or multi-layer, excluding drain, whose flexural rigidity is negligible compared to its tensile rigidity, by negligible, we mean by negligible at least 100 times lower.

[0011] The invention also allows a structure to deploy completely even if objects put pressure on the chamber to obstruct part of it, whether intentionally or not. This may be of interest in certain particular configurations.

[0012] The drain extends along a mean curve, or neutral line, between its ends As and Bs. Perpendicular to this curve, it is possible to define a section S of the drain which can be in its state at atmospheric pressure circumscribed in a rectangle of smaller area, which rectangle having a length and a width. The length of this rectangle is the greatest length Ld of the section of the drain, its width the smallest length of the section of the drain. The same applies to the sealed chamber to define the smallest length Le of the section of the sealed chamber. If the sealed chamber or the drain have variable sections, the lengths of the sections will be measured on the parts which maximize the surface area of ​​the section of the sealed chamber or the drain.

[0013] The sealed chamber comprises a flexible, waterproof material such as a polyvinyl chloride plastic film, rubber such as butyl or any other material known for making reinforced or non-reinforced sealed chambers.

[0014] The invention is more particularly dedicated to inflatable structures with air or neutral gas such as nitrogen but it can be used for any inflatable structure with an inflation fluid for which the sealed chamber is suitable.

[0015] The advantage of inflatable flexible structures is that they are flexible and pliable to occupy a much larger volume in their inflated forms than in their deflated forms. It is not appropriate for the installation of the drain in the inflatable structure to involve stiffening the structure beyond what is reasonable. The drain is therefore deformable, elastic and also flexible to be pliable and maintain the flexibility of the structure. This excludes drains being metal pipes, rigid plastics without however excluding the use of these materials by combinations making it possible to obtain such flexibility. To maintain this property, a preferred solution is for the drain to be elastic and its compression modulus to be at most equal to 1 MPa, preferably less than 0.1 MPa.To measure the compression modulus, a force-displacement curve measurement will be adapted over a significant length of the drain by applying the force perpendicular to the normal vector to the drain section. Those skilled in the art will know how to either use existing standards such as ASTDM D3574 for foams, or generalize their principles. The drain does not necessarily have a constant section, but for ease of construction, it is advantageous for the drain section to be constant. In the case of a non-constant section, several measurements can be made if necessary.

[0016] Thus a preferred solution is that the drain is a three-dimensional fabric, called 3D fabric, or a foam, or a pipe, plastic, rubber, reinforced or not, opening or multi-perforated, namely with a multitude of perforations allowing the circulation of the inflation fluid at all points of the sealed chamber between the ends of the drain while maintaining compression rigidity. Such solutions have the flexibility necessary to maintain the interest of the flexible structure, namely the relationships between the size of the inflated structure, its rigidity and its mass and the capacity to fold the structure once deflated.The person skilled in the art, depending on the intended use of the structure, will know how to size the 3D fabric, the foam and the rubber or plastic hose so that under a given pressure higher than the nominal pressure applied to the inflatable structure and preventing the circulation of the inflation fluid in the sealed chamber between the ends of the drain As and Bs, the drain always allows the circulation of the inflation fluid between the ends of the drain or, if necessary, between all the points located between the ends of the drain. The advantage of these solutions, particularly 3D fabrics, is that in certain uses even . at pressure levels much higher than the nominal inflation pressure, these fabrics become rigid in compression while remaining porous to the inflation fluid, in particular an inert gas. A 3D fabric is a fabric comprising at least two superimposed woven layers comprising a plurality of wefts and warps, the different wefts and warps creating a fabric with a thickness, for example, such that two superimposed fabrics of low thickness are linked by one or more threads thus creating thickness, or for example such that the wefts and warps pass from one superimposed layer to the other (US6103641A1, EP3545124B1).

[0017] The drain is at least adherent to the sealed chamber at its ends in order to perform its function. This adhesion can be done by any known physical means, seams, glue, thermal or chemical welding, laser, etc. A preferred solution to prevent the movement of the drain between its two ends from creating stresses at the points of junction of the drain to the sealed chamber is that it is adherent to the inflatable structure or to the sealed chamber at at least one point between the two ends As and Bs of the drain, preferably at numerous regularly spaced points whose distance is at most equal to 20 cm, preferably continuously between As and Bs.

[0018] A preferred solution is that the volume of the drain represents at most 10% of the volume of the inflatable structure in its inflated state at the nominal pressure, the drain not having to significantly increase the volume of the structure, particularly in its deflated state.

[0019] It is preferred that the drain has a thickness at atmospheric pressure at most equal to 5 cm, preferably 2 cm. This solution was used for an inflatable structure composed of several 10 m long tubes, substantially cylindrical with a diameter of approximately 45 cm in the inflated state with acceptable operation.

[0020] In the case where the drain allows the inflation or deflation of the structure, it is advantageous for one of the ends As or Bs of the drain to be at a distance at most equal to 10 cm from an access to the at least one sealed chamber. This option allows for circulation of the fluid in the entire sealed chamber where the drain is located regardless of the folding state of the sealed chamber. This can allow in certain cases automatic inflation, even if folds or twists of certain sealed chambers assembled in series prevent the circulation of air in the structure.And likewise, the drain, being connected to an access of the sealed chamber, allows a vacuum pump to remove the inflation fluid in all parts of the sealed chamber in which it is present, without human intervention, whatever the deflation dynamics of the structure even if the latter tends to make folds or twists, preventing, in the absence of the drain, the emptying of all the inflation fluid from the sealed chamber.

[0021] It is advantageous for the inflatable structure to comprise reinforcing elements, preferably textile reinforcing elements. For example, the inflatable structure may be a membrane comprising textile reinforcements coated in a polymer matrix ensuring the cohesion of the reinforcements and the sealing. The inflatable structure may also be composed of superposition of layers, preferably from the inside to the outside of the structure, a polymeric waterproof layer, reinforcing layers absorbing the pressure forces. The reinforcements are preferably natural or synthetic textile fibers to maintain the flexibility of the structure in the deflated state while giving it rigidity in the inflated state, particularly in bending, torsion and traction. There may be several layers of reinforcing elements depending on the needs of the use, to protect the sealed chamber for example, or to increase the rigidities.The angles of the reinforcing elements can also vary as required.

[0022] Some inflatable structures have sealed chambers that contain internal membranes, or other devices based on pressure load-recovery cords connecting two opposite faces of the sealed chamber, which can, but without any guarantee of the result, partially avoid this type of problem. Indeed, these load-recovery devices form folds in the event of torsion or compression and, in certain configurations, constitute a natural drain between the different points that they connect. However, a membrane connecting two faces of a sealed chamber, or another system generally increases the mass of the sealed chamber by 30%, which is not acceptable for maintaining the optimal lightness of the structure. The invention makes it possible, compared to these systems, to guarantee the solution while optimizing the weight of the structure, the lightness of inflatable structures being one of their primary interests.For this, the drain should be light and compact and its length should be optimized to reach both ends. Thus, it is preferred that the length of the drain be at most 1.5 times the curvilinear distance between points As and Bs in the sealed chamber. For manufacturing reasons, the drain may be a little longer than its geometric optimum in the chamber, which is the curvilinear distance between points As and Bs, but only to a limited extent. In addition, to optimize weight, the drain section must be significantly smaller than the section of the sealed chamber, and therefore the long length L of the section S of the drain is at least less than 0.25 times the short length Le of the section of the sealed chamber. By drain length, we mean the length of the average or neutral line of the drain.

[0023] For certain intended uses, it is preferred that the drain have a volume flow rate under the nominal pressure at least equal to 1 m3 / h, which allows inflation and deflation with an acceptable speed of the structures, the objective of the drain not being to assist in the inflation of the entire structure but to allow minimal inflation of all the sections where it is present, once this first inflation is done and the chamber is slightly inflated, the inflatable fluid passes naturally through the chamber.

[0024] It is always possible to imagine a structure where the drain has only its ends in the sealed chamber and is outside between the two - in this case the drain is itself sealed from one end to the other. However, for the uses envisaged, in order to be able to supply inflation fluid to all sections of the sealed chamber common with the drain, it is advantageous for the drain to be located in the sealed chamber. A preferred solution is moreover that the drain allows the circulation of the inflation fluid at any point of the drain located between the two ends As and Bs of the drain.

[0025] As one of the advantages of the solution is to allow improved inflation and deflation methods either by automation or by limiting human intervention, the invention includes: • Method of inflating an inflatable structure by the use of a pump or a compressor in which a pressure greater than the inflation pressure is applied to the inflatable structure for a moment between the ends of the drain As and Bs, preventing the inflation fluid from circulating between As and Bs except through the drain, the inflation fluid circulates at this moment through the drain from the access to the sealed chamber towards one of the ends As or Bs. • Method for deflating an inflatable structure by compressing the structure or by pumping the inflation fluid, in which a pressure greater than the inflation pressure is applied to the inflatable structure between the ends of the drain As and Bs, preventing the inflation fluid from circulating for an instant between As and Bs except through the drain, the inflation fluid circulates at least at this instant through the drain of one of the ends As or Bs towards the access to the sealed chamber.

[0026] By pump, or compressor, we mean any device allowing the inflation fluid to be moved, and / or put under pressure: pump, compressor, fan, etc.

[0027] The invention will be better understood from Figures 1 to 3, schematics not shown to scale.

[0028] [Fig.l] represents a flexible inflation structure according to the invention comprising a sealed inflatable flexible chamber (1) comprising a sealed layer (2), a structural layer (3) provided with textile reinforcing elements taking up the pressure forces in the chamber and an access (6) to the sealed chamber. This flexible structure is represented in the inflated state by an inflation fluid (4), the sealed chamber comprising a drain (5) permeable to the inflation fluid, with ends As and Bs.

[0029] [Fig.2] represents the cross-section AA of the inflatable structure showing its smallest length Le - the chamber being of circular section, its largest length is equal to its smallest length and equal to its diameter, as well as the largest length of the drain section Ld.

[0030] [Fig. 3] shows a canopy tested for the invention, composed of 4 pillars made up of 4 watertight chambers connected together two by two by 4 crosspieces also watertight chambers. The inflation valve is unique on one of the pillars. A fabric forms a roof and provides shade or protection from the rain. The stability of the system is ensured by cables fixed to the ground, not shown here.

[0031] The invention was tested on an inflatable structure composed of several tubes at least 2.5 m long, 20 cm in diameter, assembled together to form a canopy in accordance with [Fig. 3]. This canopy, for reasons of operating cost but also safety in the event of strong and sudden winds, must be able to be stored as quickly as possible. The tubes are composed of a sealed polyurethane chamber surrounded by a structural membrane comprising polyester fibers ensuring good rigidity to the tubes once inflated to the working pressure of 0.5 bar and a burst pressure of approximately 1.2 bar.

[0032] The problem is that when the first pillar deflates under the effect of a pump, it buckles and twists the entire structure, creating folds and twists that require human intervention to ensure the inflation fluid (air) is emptied and methodical storage to reduce the risk of overpressure in the event of non-compliance with the folding, overpressure which can damage the canopy's watertightness. Furthermore, once folded, several operators are required to inflate and unfold it correctly to ensure the structure is correctly inflated and to avoid any watertight folds.

[0033] For the invention, the inventors glued a drain composed of a 3D polyester fabric of the commercial reference “T5683 Muller textile” 6 mm thick and with a section width of 100 mm in all the tubes and transverse tubes so that all the points of the structure are connected by the drain to the inflation / deflation valve. The drain remains permeable to air under a pressure at least equal to 1.5 bar. In the solution according to the invention, removing air from the canopy no longer requires human intervention once the vacuum pump is connected and folding can be done in no particular order and without any risk of overpressure in an occluded part of a tube, the drain ensuring the homogeneity of the pressure in the structure.Likewise, inflation is facilitated by the presence of the drain which means that there is no longer any need to manage the formation of folds or twists, creating sealed sub-chambers, but simply requires accompanying the unfolding of the structure in height.

[0034] This demonstrates the interest of the invention.

Claims

Claims

1. Inflatable structure comprising: - at least one sealed inflatable flexible chamber (1) capable of being filled with an inflation fluid (4) at a nominal pressure P, via at least one access (6) to the sealed chamber, the chamber having in its inflated state a section of smaller length Le, - a flexible drain (5), of a section S of greater length Ld, having at least two ends As and Bs fixed in the sealed chamber (1), - characterized in that the drain (5) is permeable to the inflation fluid (4) and capable of maintaining the circulation of the inflation fluid between the two points As and Bs of the sealed chamber (1), when a pressure greater than the nominal pressure P is applied to at least a portion of the structure such that the inflation fluid is prevented from circulating between the ends As and Bs of the sealed chamber (1) except by the drain (5), - in that the drain (5) has a volume flow rate under the nominal pressure at least equal to 1 m3 / h,- and in that the drain (5) is a three-dimensional fabric, called 3D fabric, or a foam.,

2. An inflatable structure according to claim 1 wherein the inflation fluid (4) is a gas, preferably an inert gas, such as nitrogen, or air.

3. Inflatable structure according to any one of claims 1 or 2 in which the drain (5) is elastic and its compression modulus is at most equal to IMPa, preferably less than 0.1 MPa.

4. Inflatable structure according to any one of the preceding claims in which the volume of the drain (5) represents at most 10% of the volume of the sealed chamber in its inflated state at the nominal pressure.

5. Inflatable structure according to any one of the preceding claims in which the drain (5) has a thickness at atmospheric pressure at most equal to 5 cm, preferably 2 cm.

6. Inflatable structure according to any one of the preceding claims in which one of the ends of the drain is at a distance at most equal to 10 cm from an access (6) to the sealed chamber (1).

7. Inflatable structure according to any one of the preceding claims in which the length of the drain (5) is at most equal to 1.5 times the curvilinear distance between the points As and Bs in the sealed chamber.

8. Inflatable structure according to any one of the preceding claims in which the greatest length Ld of the section S of the drain (5) is at least less than 0.25 times the small length Le of the section of the sealed chamber (1).

9. Inflatable structure according to any one of the preceding claims in which the drain (5) is located in the sealed chamber (1).

10. Inflatable structure according to any one of the preceding claims in which the drain (5) allows the circulation of the inflation fluid at any point of the drain situated between the two ends As and B s.

11. Method for deflating an inflatable structure according to one of the preceding claims, by compressing the structure or by pumping the inflation fluid, in which a pressure greater than the inflation pressure is applied to the inflatable structure between the ends of the drain As and Bs, preventing the inflation fluid (4) from circulating for an instant between As and Bs except through the drain, the inflation fluid (4) circulates at least at this instant through the drain (5) from one of the ends As or Bs towards the access (6) to the sealed chamber (1).

12. A method of inflating an inflatable structure according to one of claims 1 to 10 by using a pump or a compressor in which a pressure greater than the inflation pressure is applied for an instant to the inflatable structure between the ends of the drain As and Bs, preventing the inflation fluid from circulating between As and Bs except through the drain, the inflation fluid circulating at this instant through the drain from the access to the sealed chamber towards one of the ends As or Bs.

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