EP3433445A1

EP3433445A1 - Structural element

Info

Publication number: EP3433445A1
Application number: EP17714504.2A
Authority: EP
Inventors: Duncan Godfrey Mervyn THOMPSON
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 2016-03-24
Filing date: 2017-03-23
Publication date: 2019-01-30
Also published as: WO2017162998A1; GB2548618A; GB201605024D0

Abstract

A structural element (20) comprising a plurality of layers (10a, 10b), each with a plurality of inflatable ribs (12). When the ribs are in a fully inflated state, and the layers connected such that the ribs of at least one layer are orientated at an offset angle to the ribs of another layer, the structural element is substantially rigid. In use, the structural element is particularly suitable for the construction of temporary modular structures such as walls, shelters, and items of furniture or other load-bearing means.

Description

STRUCTURAL ELEMENT

The present invention relates to a structural element and its use, in particular an inflatable structural element suitable for the construction of temporary modular structures such as walls, shelters, items of furniture or other load-bearing means.

Assembling temporary structures is often desired for outdoor social gatherings, short-term infrastructure maintenance or repair, the provision of collective protection in military undertakings and environmental and/or humanitarian crisis response. Obvious examples of these types of structures include housing, such as shelters, gazebos or tents, offering protection to groups of individuals from the elements and storage for equipment and supplies. The advantages of such temporary structures, compared to structures that are permanent in nature, include the ease and speed of deployment and/or assembly, the ability to re-use the structures for more than one event and the relative simplicity in terms of manufacturing and number of parts.

Despite the advantages associated with temporary structures, there remains a logistical burden for the transport of such items, especially with respect to the weight and fold-down storage aspects of temporary structures. The issue of weight is of particular relevance for large temporary structures that utilise a high number of solid support panels, as although the mass of an individual item may be fairly minimal, the accumulative total load may prohibit cost-effective transport and limit the ability to transport other essential equipment items. While replacing solid support panels with fabric elements (for example nylon, polyester and polyvinyl chloride as used in tent fly- and ground-sheets) may alleviate the problems from a weight and fold-down perspective, it is noted that this solution brings its own disadvantages, such as a loss of rigidity and weight-bearing properties, and variable performance in terms of protection from the elements, such as the wind and rain. There currently remains a need to identify novel structural elements, particularly for the construction of temporary structures, which offer favourable lightweight, storage- efficient, and load-bearing properties, the latter in particular with respect to rigidity. The present invention seeks to address these problems.

Accordingly, in the first aspect of the present invention there is provided a structural element comprising a plurality of layers, each layer comprising: a plurality of inflatable ribs coextending across part or all of each layer; an air inlet and an air outlet to enable inflation and deflation of the ribs; a seal for retaining air within the ribs when inflated; and means for connecting the layers, wherein the layers are arranged such that the ribs of at least one layer are orientated at an offset angle to the ribs of another layer, wherein the structural element is substantially rigid when the ribs of each layer are fully inflated.

The term' 'ribs' for the purpose of the present invention is used in particular to mean a series of individual, finger-like regions, arranged in a consecutive manner and capable of withholding a volume of air. The ribs are defined by joining regions between each rib, which act to segregate the air maintained within each rib when inflated. As a result of the arrangement of ribs, when fully inflated they collectively provide a substantially planar layer, wherein the surface is not completely flat but instead possesses a regular arrangement of undulations provided by the curved surface of the ribs.

The terms 'air inlet' and 'seal' for the purpose of the present invention are used in particular to mean features that operate respectively to facilitate air being directed into, and retained within, the inflatable ribs of a given layer. These features therefore provide for inflation of the structural element and maintaining the element in an inflated state. The term 'air outlet' for the purpose of the present invention is used in particular to mean a feature that facilitates air being evacuated from the inflated ribs of a given layer in order to deflate the structural element. Thus, the 'air outlet' will be considered to require a seal, the seal being removable to facilitate the release of air from the inflated ribs of a given layer. The release of air can be aided by, for example, applying an external pressure onto the ribs to force air out of the air outlet. The terms 'air inlet', 'seal', and 'air outlet' are well known to those skilled in the art. For example, the air inlet and air outlet can take the form of a valve, capable of receiving the needle insert of an air pump, the air pump providing a means of forcing air into the inflatable ribs of a given layer to a desired pressure by a user. Alternatively, the air pump can be operated to extract air out of the inflated ribs of a given layer. The term 'seal' includes a plug capable of fitting tightly into the air inlet (and/or the air outlet). Alternatively, the seal may comprise a section of material capable of extending over the air inlet (and/or air outlet) and fixed by adhesive to a region of the layer to prevent release of air from the inflated ribs.

It is to be understood by the skilled person that the air inlet, seal and air outlet features cover a multitude of arrangements. Thus, it is appreciated that the air inlet and air outlet can for example be one and the same for each layer, for example a reversible valve capable of being sealed and defined only by the intended movement of air into (via an air 'inlet'), or out of (via an air 'outlet'), the ribs. Alternatively, the air inlet and air outlet can be separate features, each provided with a seal. In a preferred arrangement, each layer contains one sealable air inlet/air outlet, which can ensure air is directed to, or from, each rib. This can be achieved, for example, by ensuring the air inlet/air outlet communicates with a common air channel, arranged to supply air to, or direct air from, the ribs of a given layer, to facilitate efficient inflation or deflation respectively.

The term 'substantially rigid' refers to a high tolerance of the structural element to flexing due to the application of a force or load. The skilled person will understand the likely range of forces to be applied to the structural element on account of its intended use.

The Applicant has found that the structural element of the present invention offers a number of advantages. Firstly, arranging the layers in an offset manner overcomes the flexibility possessed by an individual layer, thus providing a surprisingly rigid structure relative to its lightweight nature. Secondly, the layers in their uninflated state can be folded for ease of storage, thus assisting from a logistics perspective. Thirdly, preparing individual layers for incorporation into a larger structure requires simple inflation, which can be rapdily achieved using known air pump systems, thus aiding rapid assembly. Preferably all layers are arranged with respect to each other such that the ribs of all neighbouring/adjacent layers are orientated at an offset angle to each other. Thus, in a further embodiment of the first aspect of the present invention, there is provided a structural element wherein the layers are arranged such that the ribs of each layer are orientated at an offset angle to the ribs of an adjacent layer. The skilled person would appreciate that arranging the ribs of each layer, such that they are orientated at an offset angle to the ribs of an adjacent layer, ensures consistent rigidity when the ribs of each layer are fully inflated. Furthermore, such an arrangement can help minimise the numbers of layers while providing a highly rigid structure when the ribs of each layer are fully inflated.

The offset angle may be identical throughout the structural element. However, alternatively the offset angle between neighbouring/adjacent layers may vary throughout the structural element. In a preferred embodiment, the offset angles are approximately identical throughout the structural element. For example, the use of two layers, arranged such that the inflated ribs of the first layers are orientated perpendicular to the ribs of the second layer, provides a cross-like arrangement of ribs with an offset angle of 90°. However, it is to be understood by the skilled person that any number of layers could be used, arranged such that an approximately identical offset angle is provided. For example, three layers could be arranged such that ribs of a given layer are angled at 60° relative to the ribs of an adjacent layer (or to any one of the layers of the assembled structural element). Alternatively, four layers could be arranged such that ribs of a given layer are angled at 45° relative to the ribs of an adjacent layer (or to any one of the layers of the assembled structural element). It would be understood by the skilled person that the number of layers required would be dependent upon the size, shape and force-bearing characteristics of the desired structural element once assembled. In an embodiment of the first aspect of the present invention, the offset angle ranges from approximately 45-90°. Further preferably, the offset angle between the ribs of each adjacent layer is approximately 90° or 45°. These embodiments provide the advantage of a uniform structural rigidity to the structural element. From a manufacturing perspective, 90° is preferred as an offset angle as this angle permits layers of the same size e.g. square layers to be overlaid.

However, it is to be understood by the skilled person that any offset angle could be used, such as an offset angle between approximately 1 ° and 90°, for example 5°, 10°, 15°, 20°, 30°, 40°, 50°, 60°, 70° or 80°. Reducing the offset angle could be achieved, for example, by increasing number of layers comprising the structural element.

In a further embodiment of the first aspect of the present invention, there is provided a structural element wherein the means for connecting the layers comprises an adhesive, banding, frame or welding. This embodiment ensures the layers remain co-arranged such that, when the ribs of the layers are fully inflated, the structural element retains its structural integrity. Thus, it is envisaged that an adhesive would be applied between adjacent layers to ensure the layers are coupled. Alternatively, banding, such as an elastic banding, could be arranged to wrap around the main outward facing surfaces of a structural element comprising any number of layers, thus keeping the arrangement of the layers intact when the ribs of each layer are fully inflated. A frame could provide a means for inserting each layer, when the ribs are inflated, such that the layers would be held together sequentially in close or touching proximity. Connecting the layers using the technique of welding (e.g. hot wedge, ultrasonic) ensures that the connecting means is integral to the structural element, i.e. the layers remain attached in both their inflated and deflated states.

In a further embodiment of the first aspect of the present invention, there is provided a structural element wherein each layer comprises a thermoformed plastic. This embodiment provides the advantages of a lightweight material that can be generated using known methods of manufacture, which retains a high degree of flexibility when the ribs are in a deflated state, and yet provides a sturdy material when the ribs are fully inflated. Preferably, the thermoformed plastic is a commonly-used variety, such as polyvinyl chloride, polypropylene or polyethylene. However, it is understood that other types of thermoformed plastics may be chosen as desired by the skilled person.

In a further embodiment of the present invention, there is provided a structural element wherein at least one of the layers further comprises a camouflage means, a water-proof means and/or a vapour-proof means (for example against water vapour, toxic industrial chemical vapour, chemical weapon agent vapour). Such means will preferably be associated with an outer layer of a structural element. Thus, a plurality of structural elements, arranged as part of a larger structure (e.g. a tent), are positioned such that the means would be located on the external-facing or internal- facing surface of the structure. Such means will be known to those skilled in the art, and are advantageous in particular for the construction of temporary structures deployed for military or humanitarian purposes. For example, a camouflage means may comprise decorating an outer layer of each structural element with a particular pattern, or applying to said layer material decorated by such a pattern, thus aiding with concealment of the structural element, and resulting larger structure, with the surrounding environment. A vapour-proof means and/or water-proof means may comprise an additional layer of material, known by the skilled person to offer such properties, connected to an outer layer of each structural element.

In a further embodiment of the present invention, there is provided a structural element wherein one of the layers, preferably the outer layer, further comprises a light-reflective means. Furthermore, the ribs of each layer could be filled with an inert gas. This arrangement would assist in preventing the transfer of heat across the light-reflective means and layers of the structural element, which may be advantageous in a hot environment.

In a yet further embodiment of the present invention, there is provided a structural element wherein one of the layers, preferable the inner layer, further comprises a light-absorptive means, for example a dark layer or material. Furthermore, the ribs of each layer could be filled with an inert gas. This arrangement would assist in preventing the transfer of heat across the light-absorptive means and layers of the structural element, which may be advantageous in a cold environment.

In a further embodiment of the present invention, there is provided a structural element wherein the ribs are filled with a liquid or powder. This means of expanding the ribs of each layer to an inflated-like state will provide a denser structural element better equipped to deal with an impact force. This feature thus provides a structural element more suitable for an armour-type covering, with the liquid- or powder-filled ribs offering greater ballistic protection relative to ribs filled just with air.

In a second aspect of the present invention, there is provided the use of at least one structural element as described above for a modular structure. The term 'modular structure' refers to a structure comprising a plurality of structural elements, arranged to a desired format to meet a particular set of dimensions or shape as understood by the skilled person.

Thus, in a first embodiment of the second aspect of the present invention, there is provided the use of at least one structural element for a modular structure wherein the modular structure is a wall, shelter, item of furniture or other load-bearing means.

In a further embodiment of the second aspect of the present invention, there is provided the use of at least one structural element for a modular structure wherein the modular structure is an origami structure. This embodiment provides that the lightweight, rigid structural elements, achieved when the ribs of each layer are fully inflated, are encompassed in an origami arrangement (i.e. using the principles of the traditional art of origami to produce large-scale structures, as understood by the skilled person), wherein the arrangement of the walls produces structurally sound temporary constructions. The present invention will now be described, by way of example only, with reference to the following non-limiting examples and figures in which:

Figure 1 is a perspective view of an inflatable structure used as a packaging material as known in the prior art.

Figure 2 is a part-cutaway view of an embodiment of the structural element of the present invention; and

Figure 3 is an exploded perspective view of the structural element of Figure 2.

Figure 1 shows an air-fillable product (10) of EP2384994 in a fully inflated state, comprising a series of consecutively-arranged, inflatable ribs (12). The ribs (12) are defined by joining regions (14) between each rib (12), which act to segregate the air maintained within each rib (12) when inflated. The ribs (12) can be inflated via an air inlet (not shown), using an air pump, and sealed with a sealing means (also not shown) to retain the air within the ribs (12). Rather than filling each rib (12) individually, an air channel (16) is provided to ensure air flows into each rib (12) during inflation. When the ribs (12) are fully inflated, the air-fillable product (10) is semi-rigid. For example, the air-fillable product (10) is rigid if attempts are made to bend the ribs (12) in a top-to-bottom direction. However, the air-fillable product (10) is still flexible in a horizontal plane, on account of the joining regions (14) between each rib (12) rendering the air-fillable product (10) amenable to significant repositioning and flexing, and thus not substantially rigid in its inflated state. The air- fillable product (10) provides desirable properties in terms of a low weight when assembled by inflation and reduced fold-down storage when deflated. Furthermore, the air-fillable product (10) utilises the cushioning effect of compressed air and, as a result, is used primarily for packaging to limit damage to any materials or equipment during transportation. However, in light of a lack of overall rigidity, the air-fillable product (10) is not considered suitable as a structural element.

Figures 2 and 3 show a structural element (20) of the present invention with two separate layers (10a, 10b), wherein the ribs (12) of each layer are fully inflated and arranged such that the inflated ribs of the first layer (10a) are orientated perpendicular to the ribs of the second layer (10b) (i.e. at approximately 90°), thus providing a cross-like arrangement of ribs with an offset angle of 90°. In use, the layers (10a, 10b) of the structural element (20) are inflated to a fully inflated state using an air pump, and joined via an elastic banding (not shown) placed about end regions of the layers (10a, 10b), such that the layers are in contact in accordance with Figure 2.

Various modifications will be apparent to those skilled in the art. For example, the dimension of the layers will be defined according to the intended use and size of an individual structural element, or modular structure defined by a plurality of structural elements. It would be understood by the skilled person that the number of layers required and/or offset angle chosen would be balanced against the envisioned size, shape and force-bearing characteristics of the desired structural element. This understanding would also translate to the structural elements comprising a modular structure. Increasing the number of layers may provide for a reduced offset angle, for example 5°, 10°, 15°, 20°, 30°, 40°, 50°, 60°, 70° or 80°. Indeed it is to be understood by the skilled person that any offset angle could be used, such as an offset angle between approximately 1 ° and 90°. Although a means of connecting the layers (not shown) would be understood by a person skilled in the art to include an adhesive, banding, frame or welding, alternative options could be adopted. It is to be understood by the skilled person that the air inlet, seal and air outlet features cover a multitude of arrangements. Furthermore, while it is envisaged that the layers of the structural element would comprise thermoformed plastic, such as polyvinyl chloride, polypropylene or polyethylene, it is understood that other types of material, in particular alternative thermoformed plastics or coated fabrics, may be chosen as desired by the skilled person. Alternative types of gas, for example neon gas, may be used to fill the ribs of at least one of the layers of the structural element.

Claims

1 . A structural element comprising a plurality of layers, each layer comprising: a plurality of inflatable ribs coextending across part or all of each layer; an air inlet and an air outlet to enable inflation and deflation of the ribs; a seal for retaining air within the ribs when inflated; and means for connecting the layers, wherein the layers are arranged such that the ribs of at least one layer are orientated at an offset angle to the ribs of another layer, wherein the structural element is substantially rigid when the ribs of each layer are fully inflated.

2. A structural element according to Claim 1 wherein the layers are arranged such that the ribs of each layer are orientated at an offset angle to the ribs of an adjacent layer.

3. A structural element according to Claims 1-2 wherein the offset angle ranges from approximately 45-90°.

4. A structural element according to Claim 3 wherein the offset angle is approximately 90°.

5. A structural element according to Claim 3 wherein the offset angle is approximately 45°.

6. A structural element according to Claims 1 -5 wherein the means for connecting the layers comprises an adhesive, banding, frame or welding.

7. A structural element according to any preceding claim wherein each layer comprises a thermoformed plastic.

8. A structural element according to Claim 7 wherein the thermoformed plastic is polyvinyl chloride, polypropylene or polyethylene.

9. A structural element according to any preceding claim wherein at least one of the layers further comprises a camouflage means.

10. A structural element according to any preceding claim wherein at least one of the layers further comprises a water-proof means.

1 1. A structural element according to any preceding claim wherein at least one of the layers further comprises a vapour-proof means.

12. A structural element according to any preceding claim wherein at least one of the layers further comprises a light-reflective means.

13. A structural element according to any preceding claim wherein at least one of the layers further comprises a light-absorptive means.

14. Use of at least one structural element according to Claims 1 -13 for a modular structure.

15. Use of at least one structural element according to Claim 14 wherein the modular structure is a wall, shelter, item of furniture or other load-bearing means.

16. Use of at least one structural element according to Claims 14-15 wherein the modular structure is an origami structure.