Inflatable structure and method for producing an inflatable structure

Abstract

Disclosed is an inflatable structure (1) comprising a tubular textile support (10) made of seamless fabric, said support being covered with a coating layer made of a thermoplastic polymer material and being closed at its ends (3, 4) so as to obtain a chamber sealed to an inflation gas, wherein walls (7) of said chamber have a surface density of less than 1000 g / m2.

Description

INFLATABLE ASSEMBLY AND METHOD FOR MANUFACTURING AN INFLATABLE ASSEMBLY

[0001] The present invention relates to the field of inflatable assemblies used in inflatable structures, structures of the type comprising at least one inflatable assembly forming a beam which makes up the framework of enclosures, shelters or inflatable tents when the framework is covered with a canvas, or structures of the type comprising one or more inflatable assemblies assembled together and used in the manufacture of furniture or floating objects.

[0002] Inflatable beams of the type comprising a fabric envelope which encloses an inflatable tube are known in the field of inflatable structures. Inflatable tubes are generally tubular in shape and are equipped with inflation valves. Such a tubular tube is obtained by rolling a film of a polymer material around itself, then connecting the two longitudinal edges using a longitudinal weld to obtain an open tube, followed by two welds at the ends to close the tube. After inflation, the tubes function as beams, they ensure the stiffening of the frame. An inflatable structure is obtained by making a textile envelope by cutting according to a given pattern, then sewing the edges of the fabric so as to give it a tubular shape, followed by sewing different tubular envelopes together to obtain the desired shape, for example an arch or crosspiece shape.Several previously made tubular tubes are inserted inside the fabric envelope thus made, which stiffens when the tubes are inflated. These structures are very light while being sufficiently rigid once inflated. The inflation pressure is generally between 0.1 and 0.5 bar, and most often between 0.2 and 0.35 bar.

[0003] Self-supporting inflatable enclosures are known from documents FR3069001 or FR3092126. These enclosures comprise a structure comprising beams and spacers which support a covering separating the internal part of the enclosure from the exterior. Such enclosures are very light, they are generally made from flexible materials and their manufacture requires particular attention with regard to the dispersions of shape and dimensions of their geometry due in particular to manufacturing tolerances. We have thus realized that sewing operations were not only very time-consuming and labor-intensive, but that they were also a source of manufacturing defects.

[0004] Document US 2011 / 253184 is also known, which describes an inflatable tent made of a very light fabric. According to this document, the adjacent edges of the tent fabric are folded over each other and welded to obtain air ducts which, when inflated, form the arches of the tent. In order to seal the air passages, the walls of the air ducts are covered with a certain thickness of airtight material. The air ducts thus obtained are, however, of a fairly small diameter, which limits their scope of use. Furthermore, the production of the air duct requires preliminary operations of cutting the fabric, assembling its edges and welding, in addition to coating, operations which lead to high manufacturing costs.

[0005] An objective of the invention is to remedy the drawbacks of the aforementioned documents and to provide an original solution for the production of an inflatable assembly produced economically, while being reliable in operation, and capable of being inflated to high inflation pressures.

[0006] This objective is achieved by the invention which provides an inflatable assembly comprising a tubular textile support made from a seamless fabric, said support being covered with a coating layer of a thermoplastic polymer material and being closed at its ends so as to obtain a chamber sealed against an inflation gas, in which the walls of said chamber have a surface density of less than 1000g / m2.

[0007] In other words, the invention proposes an inflatable assembly made from a seamless tubular fabric support, a support which ensures the mechanical properties of the assembly. This support is coated with a thermoplastic polymer material which protects the fibers of the fabric of the support and ensures sealing against the inflation gas. Such an inflation gas can be an inert gas, such as nitrogen, or air. The two opposite ends of the support are closed by gluing or welding so as to remain sealed under the pressure of the inflation gas. According to an advantageous aspect of the invention, the fibers used to make the fabric support are very fine and strong threads and the coating layer is very thin, so as to obtain an inflation assembly in the form of a single chamber, therefore without additional internal chamber, and whose walls have a surface density of less than 1000g / m 2 and preferably between 750 and 920g / m 2 .

[0008] Thus, it was found, after laboratory tests, that such an inflation assembly resisted high inflation pressures, while being very light, with reduced weight compared to coated hoses, such as fire hoses. The inflation pressure can reach 5 x 10 5 Pa (5 bars) and this without any loss of sealing.

[0009] This results in an inflation unit with a simplified construction, as it no longer has an internal air chamber or an external cover sewn around it. This results in a more robust inflation unit, as critical areas exposed to the risk of leakage or tearing have been eliminated, while resisting high inflation pressures and being easier to manufacture and use.

[0010] Another advantage resulting from the elimination of seams is an improved aesthetics of the inflation assembly of the invention and a uniformity of the thickness of the coated tubular support, because the tubular support being obtained by circular weaving, then covered with a layer of coating is free from any area of ​​bonding or stitching which could create an excess thickness at its generator.

[0011] The average thickness of said coating layer may be between 0.4 and 0.8 mm and may preferably be equal to 0.6 mm.

[0012] The Young's modulus of the fabric of the said support can be approximately 500MPa. The Young's modulus is measured in the warp and weft directions of the textile fabric following the test procedure described by the ISO 13934-1 standard.

[0013] Said fabric may comprise warp threads and weft threads made of a material chosen from: polyester, polyamide, polyethylene, said material may preferably be a polyester. These threads thus have a very high tenacity and can advantageously be used to produce a weft having a low grammage.

[0014] The weight of said fabric can be between 300 and 600 g / m 2 , preferably between 350 and 500 g / m 2 and even more preferably it can be around 440 g / m2. A such fabric is sufficiently dense to withstand the mechanical tensile stresses of the inflation gas.

[0015] The material used for the coating layer may be thermoplastic polyurethane, preferably based on polyether polyols. Such a material has good adhesion to the support fabric and has excellent resistance to microbiological and fungal attacks that may be due to microorganisms present in the inflation gas.

[0016] Said chamber may comprise an inflation valve mounted in a sealed manner on the coated fabric of the chamber wall. This allows the sealed chamber to be easily inflated and deflated.

[0017] Inflatable assembly according to one of the preceding claims, characterized in that said chamber can be adapted to be inflated up to 5 x 10 5 Pa (5 bars). This produces an inflatable unit without an internal chamber, ultra-light and which can be inflated to high pressures, with virtually no loss of airtightness.

[0018] The objective of the invention is also achieved with a method for manufacturing an inflatable assembly, characterized in that it comprises the following steps in order: a) production of a seamless tubular textile support by circular weaving, b) coating by extrusion of a layer of thermoplastic polymer material of the support produced in the previous step, c) turning over the coated support from the previous step, and d) closing the ends of said support after having provided for the installation of an inflation valve.

[0019] The method of the invention may comprise an additional step c'), prior to step d), of inflating using water vapor the coated support obtained in step c).

[0020] In a variant of the process, a thermoforming step can be added to the inflatable assembly so as to give it an arch shape.

[0021] Step d) of the method of the invention can be carried out by welding the ends of the inflatable assembly. The ends of the inflatable assembly are welded by HF or ultrasonic welding.

[0022] The invention will be better understood from the remainder of the description, which is based on the following figures: Figure 1 is a schematic perspective view of an inflatable structure for an inflatable enclosure of known type; Figure 2 is a perspective view of an inflatable assembly of the invention; Figure 3 is a view of the coated support which makes up the inflatable assembly of the invention during its manufacture; Figure 4 represents the steps of the method of manufacturing an inflatable assembly of the invention; and Figure 5 schematically illustrates the steps of the method of the invention according to another embodiment.

[0023] In the various figures, identical or similar elements bear the same reference. Their description is therefore not systematically repeated.

[0024] Figure 1 illustrates an inflatable structure 100 of the state of the art, a structure which in this example is an inflatable enclosure comprising a framework 101 made from several inflatable tubes of the state of the art. The inflatable tubes have a generally tubular shape, they are made from an airtight film by successive manufacturing and assembly operations to form a sealed air chamber. After manufacturing, the inflatable tubes are inserted into a textile envelope. The textile envelope may contain one or more inflatable tubes and it is made by sewing in order to take the shape of an element of the framework of the enclosure, such as a beam, an arch or a crosspiece.

[0025] Figure 2 illustrates an inflatable assembly 1 according to the invention. It comprises a tubular textile support 10 coated with a layer of thermoplastic polymer material on the internal face of its walls 7, as will be detailed later. The support 10 has an elongated shape and is sealed at its ends 3 and 4, for example using a bonding device 40. The sealed closure of the support can be achieved by depositing a layer of glue between the end walls of the support 10, walls which are pinched between two parallel flat jaws 41, 42 and tightened using screws 43. The bonding can be done cold, using an airtight and waterproof polymer type glue, such as the MS polymer-based glue from the company TEC7®. This results in a chamber sealed against the inflation gas. An inflation valve 5, which also allows deflation, completes the inflation assembly 1. The inflation valve 5 is mounted in a sealed manner on the coated fabric of the chamber wall. For this, the inflation valve 5 is glued, for example using a glue of the type previously described, or it is welded using HF or ultrasonic welding to the walls of the support 10 so as to allow inflation of the assembly from the outside, using a pump or a compressor.

[0026] In a variant of the invention, the ends 3 and 4 of the support 10 are welded, for example using HF or ultrasonic welding.

[0027] Figure 3 illustrates a tubular textile support 10 coated with a layer 20 of coating made of a thermoplastic polymer material, a portion of which has been lifted using a peeling clamp 30 in order to leave the weave armor visible underneath. The support 10 open at its ends 3 and 4 has a substantially cylindrical shape of annular section around an axis of revolution X-X'.

[0028] The weaving pattern was obtained by weaving warp threads 15 (these are longitudinally oriented threads) and weft threads 16 (these are transversely oriented threads).

[0029] The warp yarns 15 and the weft yarns 16 are, in the example described, high-tenacity filament polyester (PET) yarns. By high tenacity we mean yarns with higher mechanical strength and which hold up better over time in relation to severe external / environmental conditions: pH, humidity, temperature, time. In particular, high-tenacity PETs would be less sensitive to humidity / aging because they have a higher number-average molecular weight (Mn) and a smaller number of carboxyl groups at the end of the chain (CEG) than conventional 'low' tenacity PETs. ​​To obtain the lowest possible surface weight (grammage), the weaving is carried out with very fine warp and weft yarns. Thus, it is preferred to use PET warp yarns 15, having the following technical characteristics: 2200 dtex, 100z twist, 478 doubles ends (pairs). It is preferable to use 16 PET weft yarns with the following technical characteristics: 2200 dtex, 40z twist, 70 yarns / 10cm.

[0030] As seen in Figure 3, the weave is of the plain or canvas type, it was obtained by inserting alternating weft threads 16 on warp threads 15 to obtain the same sides on the right side and on the wrong side. This type of weave has the greatest number of interactions between the warp threads and the weft threads and is quite uniform, even quite smooth on the surface. The weave obtained by weaving the warp threads 15 and the weft threads 16 of the example described has an average thickness of approximately 0.45 mm and a weight per unit area (or grammage) of approximately 440 g / m 2 .

[0031] The armor of the support 10 of the invention was obtained by circular weaving of the warp 15 and weft 10 threads using a circular weaving machine, for example of the HM604 type from the company MANDALS®.

[0032] The armor thus obtained is then covered with a layer 20 of coating which is preferably thermoplastic polyurethane (TPU) and preferably TPU based on polyether polyols. This material has very good adhesion properties to the woven armor of the support 10 and forms a good barrier to inflation gases (it has a low air permeability factor, of approximately 0.5m 3 / h / m 2 ). Furthermore, this material has excellent resistance to microbiological and fungal attacks. Such a material has a Shore A hardness of approximately 86-88. The thickness of the coating layer 20 is approximately 0.6 mm. The density of the material of the coating layer 20 is approximately 1.12 g / cm 3 .

[0033] The steps of the manufacturing method of an inflatable assembly 1 of the invention will be explained with reference to Figure 4.

[0034] The first manufacturing step is that of circular weaving a) of the warp threads 15 and the weft threads 16 on a circular loom. This produces a tube of a predetermined length and diameter which is subjected to a coating step b). Step b) is carried out by extruding a thin layer of TPU onto the flattened tube obtained in step a), the tube being the right way up. Then, an operation of turning the tube from step b) is carried out and an upside-down tube is obtained, so that the coating layer 20 is inside the tube after turning it over. This produces a support 10 having good sealing of the tube in contact with the inflation gas while avoiding any delamination, for example by abrasion, of the coating layer 20. The inflation valve can then be glued or welded and the ends 3 and 4 of the support 10 sealed.

[0035] In a preferred embodiment of the invention, the coated and returned tube obtained in step c) is subjected to an inflation operation using steam at a temperature of approximately 130-140°C and a pressure of approximately 2 bar for a period of approximately 10 min. This allows the coated tube to regain its diameter, following the contraction it underwent during the extrusion step b). Following this operation, the diameter of the tube increases by approximately 10 to 12% and the coating layer 20 stretches and becomes uniform so as to obtain a surface density (or density) of approximately 950 to 1000 g / m 2 .

[0036] Then add the inflation valve and seal the ends of the support to obtain an inflation assembly 1.

[0037] For example, a set 10 thus obtained has a diameter of approximately 250 mm and can be inflated up to 5 x 10 5 Pa (5 bars) without loss of tightness.

[0038] Figure 5 illustrates an additional operation of the method for obtaining an inflatable assembly 1 of the invention. More precisely, it is an operation of thermoforming the inflation assembly 1 obtained as previously described.

[0039] Thus, thermoforming begins with a step i) of heating the inflatable assembly 1 to a temperature of approximately 100°C while keeping it flat, or according to a support arranged in an axial direction, being held at each end by a vice 50. By axial direction, we mean the direction substantially parallel to the axis of revolution X-X' of the support 10 of the inflation assembly. In step ii), the support 10 is then fixed with its vices 50 on a rounded wedge 52. In step iii), the support 10 is subjected to inflation using water vapor at a temperature of approximately 130-140°C and a pressure of approximately 2 bar for a period of approximately 10 min. This allows the support 10 and therefore the inflation assembly to take the arcuate shape illustrated in step iv). An arch-shaped inflation assembly 1' thus obtained has improved rigidity compared to the arches of the frame 110 of FIG. 1 of the prior art.

[0040] The inflation assembly 1, 1' according to the invention can be used to construct the framework of an inflatable enclosure, for example of the type illustrated in Figure 1, more economically, with fewer components and less labor for the manufacture and assembly of these components, while giving more rigidity to the framework.

[0041] Other variants and embodiments of the invention may be envisaged within the scope of the invention as claimed. Thus, the ends of the inflation assembly 1 may take other shapes than that illustrated, for example a curved shape or a flat shape.

Claims

Claims 1. Inflatable assembly (1, F) comprising a tubular textile support (10) made of a seamless fabric, said support being covered with a layer (20) of coating made of a thermoplastic polymer material and being closed at its ends (3, 4) so ​​as to obtain a chamber sealed against an inflation gas, in which walls (7) of said chamber have a surface density of less than 1000g / m 2 .

2. Assembly according to claim 1, characterized in that the average thickness of said layer (20) of coating is between 0.4 and 0.8 mm and is preferably equal to 0.6 mm.

3. Assembly according to one of the preceding claims, characterized in that the Young's modulus of the fabric of said support is approximately 500 MPa.

4. Assembly according to one of the preceding claims, characterized in that said fabric comprises warp threads (15) and weft threads (16) made of a material chosen from: polyester, polyamide, polyethylene and the material is preferably a polyester.

5. Assembly according to one of the preceding claims, characterized in that the weight of said fabric is between 300 and 600 g / m 2 , preferably between 350 and 500 g / m 2 .

6. Assembly according to one of the preceding claims, characterized in that said thermoplastic polymer material is thermoplastic polyurethane, preferably based on polyether polyols.

7. Assembly according to one of the preceding claims, characterized in that said chamber comprises an inflation valve (5) mounted in a sealed manner on the coated fabric of the wall (7) of the chamber.

8. Inflatable assembly according to one of the preceding claims, characterized in that said chamber is capable of being inflated up to 5 x 10 5 Pa (5 bars).

9. Method of manufacturing an inflatable assembly (1,1') characterized in that it comprises the following steps in order: a) production of a seamless tubular textile support (10) by circular weaving, b) coating by extrusion of a layer (20) of thermoplastic polymer material of the support produced in the previous step, c) turning over the coated support from the previous step, and d) closing the ends (3, 4) of said support after having provided for the installation of an inflation valve.

10. Method according to the preceding claim, characterized in that it comprises an additional step c'), prior to step d), of inflating using water vapor the coated support obtained in step c).

11. Method according to one of claims 9 or 10, characterized in that it comprises a step of thermoforming the inflatable assembly so as to give it an arch shape.

12. Method according to one of claims 9 to 11, characterized in that step d) is carried out by welding the ends (3, 4) of the inflatable assembly.

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