Patent Description:
Conventional cycling helmets are formed of solid, rigid material, and therefore have a particular permanent size and volume. This can be inconvenient, particularly because there may be little room to store a conventional cycling helmet. It is desirable to have a cycling helmet that is inflatable, and can therefore collapse and be compressed to a compact form when not in use, and re-inflated for use. However, inflatable structures often lack strength and rigidity.

A known inflatable helmet is described in European Patent No. <CIT>. This uses a lattice-like structure to form a rigid structure and discloses the preamble of claim <NUM>. <CIT> describes pneumatic caps having top and bottom walls joined by their edges to define an internal air chamber and having internal partitions with openings to maintain the concave shape of the cap when inflated.

The inventors have appreciated that the diagonal struts of the helmet described in <CIT> are subject to distortion in the event of a hard impact. Further, it is difficult to join the struts to the longitudinal members in a manner which is both strong and does not allow air to leak.

The inventors have appreciated a need for an inflatable or collapsible helmet that is capable of withstanding structural forces of the conventional impact tests required for cycling helmets (for example, EN1078). The inventors have further appreciated a need for a helmet designed to be manufactured effectively and efficiently. The inventors have further appreciated a need for a helmet that may be stored easily and effectively when not in use.

The present invention provides an inflatable helmet as defined in the appended independent claim. The inflatable helmet comprises a plurality of elongate members. Each elongate member comprises at least one chamber wall defining an inflatable chamber. At least two (or a pair of) adjacent elongate members are in fluid communication with each other. The plurality of elongate members is inflatable so as to adjust the inflatable helmet from a collapsed state to an inflated state. In an inflated state, the at least one pair of adjacent elongate members abut each other along at least a portion of their respective chamber walls.

The helmet of preferred embodiments of the present invention may be capable of being collapsed or deflated and conveniently stored away in a collapsed state until a user needs to use to it by inflating the helmet to an inflated state. By providing elongate members that are abutting each other along at least a portion of their respective chamber walls, when the helmet is inflated, the helmet of preferred embodiments of the present invention may also provide improved structural rigidity and impact performance during use in an inflated state.

Preferably, in an inflated state, adjacent elongate members of the plurality of elongate members abut each other along at least a longitudinal portion of their respective chamber walls. In other words, adjacent elongate members are either touching or are coupled to each other along at least a longitudinal portion of their respective chamber walls.

Preferably, adjacent elongate members directly abut each other along at least a longitudinal portion of their respective chamber walls. The term 'directly abut' preferably refers to the fact that two elements or components are touching or are coupled to each other, with no other intermediate elements or components, or even gaps, between them in locations where they are abutting. Preferably, in an inflated state, the (at least one pair) adjacent elongate members abut each other along a majority of the length of their respective chamber walls.

Preferably, the inflatable helmet is collapsible from an inflated state to a collapsed (or deflated) state. Preferably, the plurality of elongate members is deflatable so as to adjust the inflatable helmet from an inflated state to a collapsed state. This advantageously ensures that the inflatable helmet can be stored away after being inflated to an inflated state from a collapsed state.

Preferably, in a collapsed state, each of the elongate members is substantially flattened such that the shape of the helmet in a collapsed state is substantially flatter than the shape of the helmet in an inflated state. The shape of the helmet in a collapsed state may be substantially flatter in a transverse direction than the shape of the helmet in an inflated state.

Preferably, in the collapsed state, adjacent elongate members are joined or coupled to each other at at least one location or portion of their respective chamber walls. Preferably, in the collapsed state, adjacent elongate members are joined or coupled to each other at at least one longitudinal location or portion of their respective chamber walls. The remaining longitudinal portions, or length, of the respective chamber walls of joined, adjacent elongate members may not be coupled or joined to each other. The remaining longitudinal portions of the respective chamber walls of joined, adjacent elongate members may or may not abut each other in the collapsed state. Preferably, in an inflated state, such remaining portions of the respective chamber walls of adjacent elongate members abut each other in an inflated state. However, preferably, some of such remaining portions of the respective chamber walls of adjacent elongate members do not abut each other in a collapsed state.

In other words, in a collapsed state, adjacent elongate members are coupled to each other along a first portion of their respective chamber walls. Such a first portion (or first portions) of a chamber wall comprises, or consists of, a portion of the chamber wall that is coupled to another chamber wall. In an inflated state, adjacent elongate members may abut each other along a second portion of their respective chamber walls. In an inflated or a collapsed state, adjacent elongate members may abut each other along a second portion of their respective chamber walls. Such a second portion of a chamber wall comprises, or consists of, a portion of the chamber wall that is not coupled or joined to another chamber wall. Such a second portion of a chamber wall may comprise the majority of the length of the chamber wall. In other words, such a second portion of a chamber wall, which is configured to abut a second portion of the chamber wall of an adjacent elongate member, comprises at least <NUM> percent of the length of the chamber wall. Such a second portion of a chamber wall may comprise at least <NUM> percent of the length of the chamber wall. Such a second portion of a chamber wall may comprise at least <NUM> percent of the length of the chamber wall.

Accordingly, while adjacent elongate members may abut each other in a collapsed or deflated state, they are configured to abut each other along longer portions of their respective chamber walls in an inflated state. This is because the elongate, inflatable members are wider in an inflated state than in a collapsed state. As a result, the fluidly connected elongate members abut each other more (that is, along a greater length of their respective chamber walls) in an inflated state than in a collapsed state. Such an increase in abutment ensures there is more contact amongst adjacent elongate members in an inflated state, which advantageously ensures the helmet can sustain impact and minimise transfer of such an impact to a user's head, while also ensuring that the helmet can be stored away in a more compact form.

Preferably, the elongate members extend substantially along a longitudinal direction of the helmet. The elongate members of the helmet preferably wholly or partially extend between a rear end of the helmet and a front end of the helmet. The elongate members are preferably configured to expand laterally (that is, along a transverse direction of the helmet extending between both the left and right sides) or transversely. Accordingly, a width of each of the elongate members may be greater in an inflated state than a width of each of the elongate members in a collapsed or deflated state.

The elongate members may be substantially parallel to each other, at least in a collapsed state of the inflatable helmet. Providing the elongate members substantially parallel to each other at least in a collapsed state of the helmet, ensures that the width of the helmet is minimised so that the helmet can occupy less space and be stored easily by a user.

Each elongate member may comprise at least one aperture defined in the chamber wall. The at least one aperture of an elongate member may be fluidly connected to at least one corresponding aperture of an adjacent elongate member. This ensures there is direct abutment between adjacent elongate members in an inflated state, while establishing a fluid communication between such elongate members so that they can be inflated. The at least one aperture of an elongate member may be coupled to at least one corresponding aperture of an adjacent elongate member. The apertures are preferably coupled by welding, as described in further detail in the present disclosure.

The plurality of elongate members may comprise two external (or outer) elongate members and at least one internal (or inner) elongate member located between the external elongate members. The at least one internal elongate member may comprise at least one first aperture located on a first side of the inflatable chamber and at least one second aperture located on an opposing second side of the inflatable chamber. The at least one first aperture of an internal elongate member may be fluidly connected to at least one corresponding aperture of an adjacent elongate member. The at least one second aperture of an internal elongate member may be fluidly connected to at least one corresponding aperture of another adjacent elongate member. Preferably, the inflatable helmet comprises at least five internal elongate members. Even more preferably, the inflatable helmet comprises at least eight internal elongate members. The inflatable helmet may comprise two external elongate members and at least nine internal elongate members. Some of the internal elongate members are shorter in length than other internal elongate members and the external elongate members.

Each elongate member may comprise a plurality of apertures defined in the chamber wall. The apertures of the plurality of apertures may be longitudinally spaced amongst each other. Providing a plurality of longitudinally-spaced apertures ensures that adjacent elongate members can be fluidly connected, while providing an effective and quick inflation of the helmet.

The portion of the chamber wall surrounding the at least one aperture of an elongate member may be coupled to the portion of the chamber wall surrounding the at least one corresponding aperture of an adjacent elongate member such that an airtight seal is provided around the apertures.

The chamber wall of each elongate member may comprise an inner layer and an outer layer. This enhances the structural integrity of the chamber walls.

A portion of the chamber wall surrounding the at least one aperture may comprise one of the inner layer and the outer layer. Preferably, a portion of the chamber wall surrounding the at least one aperture may consist of the inner layer or the outer layer. Such a portion of the chamber wall may correspond to a portion of the chamber wall located at the periphery of an aperture. As discussed further below in the present disclosure, a portion of the outer layer surrounding the at least one aperture may be removed to expose the inner layer.

The chamber wall of each elongate member may comprise at least one longitudinal seam. The at least one longitudinal seam may be formed by joining a longitudinal portion of one of the inner layer and outer layer to another longitudinal portion of either the same one of the inner layer and outer layer or a different one of the inner layer and outer layer. Preferably, the at least one longitudinal seam is formed by joining a longitudinal portion of an outer layer to another longitudinal portion of either the same outer layer or a different outer layer. Preferably, the chamber wall of each elongate member comprises a first wall and a second wall. The first and second walls may be joined together by an upper longitudinal seam and a lower longitudinal seam. Alternatively, the chamber wall of each elongate member is defined by a single wall element, the edges of which are joined together to form at least one longitudinal seam, in order to form an inflatable chamber.

Preferably, each longitudinal seam is reinforced by a rib member. The reinforcing rib member may be coupled to each longitudinal seam. The rib member may enclose or encapsulate each longitudinal seam. Each elongate member may comprise at least one rib member. Each elongate member may comprise a lower rib member and an upper rib member, respectively corresponding to a lower longitudinal seam and an upper longitudinal seam.

The inner layer may comprise an outer lamina of plastic material and an inner lamina of woven material. The outer layer may comprise an outer lamina of woven material and an inner lamina of plastic material. At least a portion of the inner lamina of the outer layer overlapping the outer lamina of the inner layer may be joined to the outer lamina of the inner layer such that an airtight seal is formed between the outer and inner layers of the chamber wall.

In the present disclosure, there is also provided an inflatable article. The inflatable article may comprise a plurality of inflatable members. Each inflatable member may comprise at least one chamber wall defining an inflatable chamber. At least two adjacent inflatable members may be in fluid communication with each other. The plurality of inflatable members may be inflatable so as to adjust the inflatable article from a collapsed state to an inflated state. In an inflated state, at least one pair of adjacent inflatable members abut each other along at least a portion of their respective chamber walls. Preferably, the inflatable members may be elongate members. Preferably, in an inflated state, at least one pair of adjacent elongate members abut each other along at least a portion of their respective chamber walls. The inflatable article may be a wearable article.

Each inflatable member may comprise at least one aperture defined in the chamber wall. The at least one aperture of an inflatable member may be fluidly connected to at least one corresponding aperture of an adjacent inflatable member. The portion of the chamber wall surrounding the at least one aperture of an inflatable member may be coupled to the portion of the chamber wall surrounding the at least one corresponding aperture of an adjacent inflatable member such that an airtight seal is provided around the apertures. The chamber wall of each inflatable member may comprise an inner layer and an outer layer.

A portion of the chamber wall surrounding the at least one aperture may consist of one of the inner layer and the outer layer. The inflatable article may be inflatable from a collapsed state to an inflated state.

The inflatable article may be collapsible from an inflated state to a collapsed state. Preferably, in a collapsed state, each of the inflatable members may be substantially flattened such that the shape of the article in a collapsed state is substantially flatter than the shape of the article in an inflated state.

Preferably, the inflatable members extend along a longitudinal direction of the article. Preferably, some or all of the inflatable members are arranged substantially parallel to each other. Some or all of the inflatable members may be arranged substantially parallel to each other, in a collapsed state. The inflatable members of the inflatable article may be elongate members, with similar characteristics to those of the inflatable helmet described in the present disclosure.

The chamber wall of each inflatable member may comprise at least one longitudinal seam. The at least one longitudinal seam may be formed by joining a longitudinal portion of one of the inner layer and outer layer to another longitudinal portion of either the same one of the inner layer and outer layer or a different one of the inner layer and outer layer. Preferably, the at least one longitudinal seam is formed by joining a longitudinal portion of an outer layer to another longitudinal portion of either the same outer layer or a different outer layer.

Similar to the inflatable helmet of the present disclosure, the inner layer may comprise an outer lamina of plastic material and an inner lamina of woven material. The outer layer may comprises an outer lamina of woven material and an inner lamina of plastic material. At least a portion of the inner lamina of the outer layer overlapping the outer lamina of the inner layer may be joined to the outer lamina of the inner layer such that an airtight seal is formed between the outer and inner layers of the chamber wall.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. Furthermore, any, some and/or all features in one aspect may be applied to any, some and/or all features in any other aspect, in any appropriate combination. In particular, any method features provided in relation to the first aspect may be applied to any of the other aspects. It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention may be implemented and/or supplied and/or used independently, but the scope of protection is defined by the appended claims.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the drawings, of which:.

Referring to <FIG>, a helmet <NUM> according to an embodiment of the present invention comprises a series of longitudinal members <NUM>, <NUM>, arranged side-by-side to each other. The helmet <NUM> has a generally curved with a concave inside shape and a convex outside shape, though somewhat flattened, with a front end <NUM> and rear end <NUM> and two side edges <NUM>, and each longitudinal member <NUM>, <NUM> being curved and aligned approximately longitudinally and generally parallel to its neighbouring members, but at an increasing inclination, so that the longitudinal members <NUM>, <NUM> together form the curved profile of the helmet <NUM>. Some longitudinal members <NUM> extend fully between the front edge <NUM> and rear edge <NUM>, converging at those two regions. Other longitudinal members <NUM> are shorter, and occupy positions between the fully extending longitudinal members <NUM> that would otherwise be left between the fully extending longitudinal members <NUM> at the middle region of the helmet. All the longitudinal members <NUM> may be tapered towards there terminal ends so that they fit together in the hemispherical arrangement.

Each longitudinal member <NUM>, <NUM> is inflatable, having an airtight skin (or chamber wall) that defines an inflatable chamber, and the chambers of longitudinal members <NUM>, <NUM> are in fluid communication with each other. In <FIG>, the longitudinal members <NUM>, <NUM> are shown fully inflated, so that they assume a helmet-like shape or profile.

Referring to <FIG>, when the chambers of longitudinal members <NUM>, <NUM> are evacuated, the longitudinal members <NUM> may be compressed or collapsed in a lateral direction so the longitudinal members <NUM>, <NUM> and the helmet <NUM> as a whole attain a relatively flat state, the planar form of each longitudinal members <NUM>, <NUM> being now parallel with every other flattened longitudinal member <NUM>, <NUM>. In this deflated, relatively flat state, the helmet <NUM> takes up little room and may more conveniently be stored.

Referring to <FIG> and <FIG>, each longitudinal member <NUM>, <NUM> comprises a chamber cavity <NUM> defined by a first wall <NUM> and a second wall <NUM>. The first wall <NUM> and second wall <NUM> are joined along their respective upper edges and respective lower edges with a surface to surface connection <NUM>, where material from the first wall <NUM> and second wall <NUM> are superimposed to form a seam. Each longitudinal member <NUM>, <NUM> thus has two surface to surface connections <NUM>, one running longitudinally along the outside of the helmet <NUM>, and one running longitudinally along the inside of the helmet <NUM>. Each surface to surface connection <NUM> is encapsulated along the length (or along the majority of the length) with a linear perimeter rib <NUM>, <NUM>, which provides further structural strength and rigidity to the longitudinal members, strengthens the surface to surface connection <NUM>, spreads the load during impact across more of the chamber, and reduces friction under impact. A reduction in friction means an impact force will slide over the surface of the helmet rather than be absorbed by it. The inside linear perimeter rib <NUM> features a padded member <NUM> which extends along the inside linear perimeter rib <NUM> to provide a soft surface that sits on the user's head. The rib may be formed from nylon.

As previously described, each longitudinal member <NUM>, <NUM> is joined to the members directly adjacent to it in fluid communication, so that the helmet <NUM> may be inflated or deflated by respectively introducing or letting out air in any one of the longitudinal members.

The longitudinal members <NUM>, <NUM> are joined by nodes <NUM> formed by apertures <NUM> in the walls <NUM>, <NUM>. The aperture <NUM> of a first wall <NUM> of one longitudinal member <NUM>, <NUM> is joined to the aperture <NUM> of a second wall <NUM> of the adjacent longitudinal member <NUM>, <NUM>. This arrangement is repeated for each neighbouring pair of longitudinal members <NUM>, <NUM>. The material of the first and second walls of adjacent longitudinal members are superimposed with coincident edges, and joined in this region to form a surface to node connection <NUM>. The surface to node connection <NUM> thus has a double layer of material, and is generally annular, the aperture <NUM> being generally circular.

Referring also to <FIG>, nodes <NUM> are located along the longitudinal members <NUM>, <NUM> in a periodic manner. Considering longitudinal member <NUM>' as an example, the nodes <NUM> formed with longitudinal member <NUM> are longitudinally spaced compared to the nodes <NUM> formed with longitudinal member <NUM>. This means that air flow through nodes joining the longitudinal members cannot simply flow from one side of the helmet to the other in a straight line, but must take a convoluted path by having to travel longitudinally along the longitudinal member to the next node, with the path of air flow through the nodes being indicated by arrows a. This arrangement increases the resistance of the airflow, causing the helmet <NUM> to be stiffer in the event of an impact at a point on the helmet.

It may though be convenient to have some longitudinal members, such as the center-most longitudinal member <NUM> shown in <FIG>, to have nodes <NUM> on each side of the longitudinal member <NUM>. Such nodes 28are laterally aligned on both sides.

Referring to <FIG> and <FIG>, when air is pumped from the helmet <NUM> to deflate it, the longitudinal members <NUM>, <NUM>, contract in a lateral direction in a concertina-like manner, and the walls <NUM>, <NUM> take a planar shape, so that all the walls <NUM>, <NUM> are arranged in a generally parallel manner across the helmet, though arranged at different heights due to the hemispherical form or curved profile of the helmet <NUM>.

The first and second walls <NUM>, <NUM> are ideally formed from a double-layered material, each wall of the longitudinal member <NUM>, <NUM> being formed from an interior (or inner) layer (or lamina) <NUM> and an exterior (or outer) layer (or lamina) <NUM>. Each single layer itself ideally a laminate material, one possible embodiment of which is described in further detail in <FIG>.

To bond or join adjacent longitudinal members <NUM>, <NUM>, together at the surface to node connection <NUM> the exterior layer or lamina of a wall of each longitudinal member <NUM>, <NUM> is removed in that region, so that the two adjoining interior layers <NUM> can be secured together.

To bond the first wall <NUM> and second wall <NUM> of a longitudinal member <NUM>, <NUM>, at the surface to surface connection <NUM>, the interior layer <NUM> of the first wall <NUM> and the second wall <NUM> are both removed, and the remaining exterior layer <NUM> of the first wall <NUM> and the second wall <NUM> are superimposed and welded to create a seam.

Rather than removing a layer of the wall, the wall could be formed without the layer being present in that region.

The nodes <NUM> are placed approximately at equidistant points from each other along the length of each longitudinal member, thus spreading the forces across the structure.

An ideal material for the walls of the longitudinal members is a laminate material formed from a lamina of airtight thermoplastic polyurethane (TPU), and a lamina of woven plastic material such as Nylon <NUM>. A single layer of this laminate material, provided both lamina are intact is itself airtight by virtue of the TPU. Referring to <FIG>, a double layer material <NUM> can be conveniently formed by welding two such laminate material layers together, that is, a first sheet of laminar material <NUM>, comprising a first lamina of TPU <NUM> and a first lamina of woven material <NUM>, to a second sheet of laminar material <NUM>, comprising a second lamina of TPU <NUM> and a second lamina of woven material <NUM>, the first lamina of TPU <NUM> and the second lamina of TPU <NUM> arranged confronting each other. The first and second sheets <NUM>, <NUM> need not be co-extensive, and in this example a region <NUM> is shown where the first sheet <NUM> extends beyond the edge of the second sheet <NUM>. Such a region may run along the length of the material, for example along the first wall <NUM> where the seam <NUM> is to be formed with second wall <NUM>.

Two such sheets of double layer wall material <NUM> can be joined together by welding the exposed regions <NUM> of two sheets of material being brought together. Another way of joining two sheets of material is to remove some lamina, to form an exposed area <NUM>. <FIG>, shows a sheet of double layer wall material <NUM> where a cutaway hole <NUM> is formed through the second lamina of TPU <NUM> and second lamina of woven material <NUM> of the second sheet of laminar material <NUM> to expose the first lamina of TPU <NUM> of the adjoining face of the first sheet of laminar material <NUM>.

Referring to <FIG>, two similar sheets of double layer wall material <NUM>, <NUM>' may be brought together, with similar cutaway holes <NUM>, <NUM>' confronting each other, and the exposed portions of TPU <NUM>, <NUM> pressed together and welded to form a join between the sheets of double layer wall material <NUM>, <NUM>'. As a result, a fluid communication can be established between two longitudinal members.

Referring to <FIG>, a longitudinal member <NUM> has a first wall <NUM> and second wall <NUM> formed from the double layer wall material <NUM> shown in <FIG>. Where the longitudinal member <NUM> is to be joined by a node to a neighbouring longitudinal member <NUM>', the outermost laminae of TPU and woven material are removed to form a cutaway hole <NUM> to leave region having the structure shown in <FIG>, with an exposed region <NUM> of TPU exposed. An aperture <NUM> is formed through the TPU and woven material in this exposed region <NUM>.

In order to join the longitudinal members <NUM> with a neighbouring longitudinal member <NUM>', the other longitudinal member is similarly prepared with a cutaway hole located to confront cutaway hole <NUM>, with the apertures aligned. The TPU in the two exposed regions <NUM> are pressed together and welded. The opposing surfaces of exposed TPU welding in this manner form a secure hermetically sealed join, and the aligned apertures <NUM> through the walls of the longitudinal members allow fluid communication between the longitudinal members in the manner previously described.

The welding process for joining laminae of TPU arranged in confrontation may be high frequency (HF) welding. This process uses radio frequency energy to join the abutting TPU laminae of material due to the ultrasonic vibration of molecules within the TPU material, and gives a strength at the join which is equivalent to the base structural strength of the material itself. The resulting join between two laminae of TPU is also airtight. The node weld using this system is leak proof, is as strong as the actual base material and tested at BSI laboratory to pass an EN1078 structural drop test and repeat testing. Other forms of welding or joining may be suitable, such as heat welding or solvent welding may be used, provided the resulting welds or joins have sufficient strength and airtight sealing qualities.

The laminae of woven material may have a weave direction, and this will typically give structural properties that vary dependant on direction. Referring to back to <FIG>, the first lamina of woven material <NUM> and the second lamina of woven material <NUM> may be arranged so that that the weave direction of the first lamina of woven material <NUM> is ideally rotated <NUM> degrees from the weave direction of the second lamina of woven material <NUM>. The woven material may have both a weave and a weft, typically perpendicular to one another, so orienting one woven lamina at <NUM> degrees to the other ensures both the weave and weft of that lamina are differently oriented to both the weave and weft of the other woven lamina, providing good strength qualities in any direction. Other differing orientation angles of the two woven laminae may though be implemented.

The double wall material provides strength for the chamber of each longitudinal member when inflated or in the stress of impact; it is also resistant to stretching. Referring to back to <FIG>, the upper perimeter of the inner material <NUM> is offset with respect to the outer material to leave an upper perimeter of only the outer material <NUM> around the edges. This then allows for the outer material <NUM> of the first wall <NUM> to be welded or laminated to the outer material <NUM> of the second wall <NUM> (the second wall being similar to the first wall, but having the lamina order reversed or reflected) to form the surface to surface connection <NUM> and thus the chamber as previously described, the same process is also used at the lower region of the longitudinal members <NUM>, <NUM> to form the lower surface to surface connection.

The resulting weld seams run longitudinally along the length of the helmet structure, forming a major structural element and becomes a rib member <NUM>, <NUM> that helps constrain the forces under inflation, ultimately spreads loading forces under or during impact along the length of that particular chamber; that is, the rib stops the curved shape or profile of the longitudinal member from opening out or uncurling.

The double laminae structure also allows for a slit to be created between the laminae so that the interior nodes can be accessed from inside the chamber to be welded to the next chamber from interior to interior if desired. Once the nodes are welded, the slit is then welded up. The slit is offset so the outer lamina slit intentionally misaligns with the inner lamina to be sure there is always at least one lamina of woven material on the surface.

A weld connection point may be formed by removing a lamina of woven material and TPU material from aligned portions of double walled material and welding the confronting TPU surfaces as for forming a node, but without forming a through hole so that the connection is blank or blind, so that the adjacent longitudinal members are bonded together but are not in fluid communication at this point.

Both nodes having through hole connections, and blind weld connection points may be placed at any point along the chamber with a minimum of design alteration; the removal of one lamina of woven material and one lamina of TPU material from the double wall to form a node may be carried out.

Forming a weld or joining by removing material from the double wall material in this manner gives a flat weld connection which is equal to the thickness of the original material. Ultimately this allows the overall design to be compressed flat when not in use so that it is no thicker than the total number of layers of flat material. The weld points are in fact slightly thinner. Due to the nature of this process the forces exerted on the weld are equalised as they are distributed through the wall of the chamber, so do not build up at one point.

At nodes where a through hole aperture is formed, the size of the aperture determines the resistance to airflow during an impact, allow the strength of the chamber and structure to be predetermined. The diameter of the aperture may be at least about <NUM>. Preferably, the diameter of the aperture is at least about <NUM>. The diameter of the aperture may be less than or equal to about <NUM>. Preferably, the diameter of the aperture is less than or equal to about <NUM>. The diameter of the aperture may be between about <NUM> and about <NUM>. Preferably, the diameter of the aperture is between about <NUM> and about <NUM>. Preferably, the diameter of the aperture is about <NUM>.

Preferably, the helmet is formed as a completely sealed unit that can be inflated and deflated, preferably repeatedly. Therefore, the helmet preferably includes at least one air inlet port (not shown) that can be used to inflate or deflate the helmet. The air inlet port or valve may provide a fluid communication with at least one of the elongate members of the helmet. The air inlet port may be configured to allow air to enter and exit the helmet. Alternatively, a separate or additional air outlet port may be provided on the helmet to allow air to exit the helmet.

Preferably, an air inlet (or outlet) port is provided on one of the internal elongate members. Even more preferably, the air inlet (or outlet) port is provided on one of the elongate members that is located on, or in the vicinity of, a central portion of the helmet. This may ensure that the helmet is evenly and efficiently inflated during the inflation as well as evenly deflated during deflation.

The at least one air inlet or outlet port may comprise a valve. Preferably, such a valve may be a Schrader valve or a Presta valve. This is particularly beneficial as it means the helmet can be inflated with a conventional bicycle pump. The rigidity of the helmet material and design, particularly in an inflated state, allows for a relatively low internal air pressure within the helmet in order for the helmet to perform safely upon impact. The preferred internal pressure within the helmet in an inflated state is between about <NUM> bar (about <NUM> Psi) and about <NUM> bar (about <NUM> Psi). This may enable a user to repeatedly inflate or deflate the helmet relatively quickly and with ease.

A piece of material comprising a TPU lamina and lamina of woven material may be affixed as a patch on a first wall (having at least an outer TPU lamina) of one of the elongate members to provide a double wall in that area, and this patch may be formed with a cutaway hole to leave exposed the first lamina of TPU of the first wall so that the first wall's TPU may be brought together and welded to the TPU lamina of a neighbouring elongate member.

The principles described herein of joining inflatable members together by bonding abutting walls to form nodes (either structural joining nodes, or fluid communication nodes) may equally be applied to other inflatable articles (i.e. articles other than inflatable helmets). Similarly, the principles described herein of bonding a seam of an inflatable member may equally be applied to other inflatable articles.

The techniques described in the present disclosure are particularly suitable to inflatable articles that are required to be capable of being compressed to a flatter shape, and where relatively high rigidity in the inflated form is desirable, particularly for articles that have a safety or buffering purpose, or are subjected to large impact forces.

In particular, for inflatable articles of the present disclosure, a number of inflatable chamber members may be joined together by nodes as described in relation to helmet above, the members wholly or partially composed of a material having a first wall and a second wall which are superimposed or overlap each other, and wherein the one of these walls is absent from a region surrounding the coincident apertures. These members can then be joined by nodes in the same manner as previously described, and conveniently they can employ the same structure of first and second lamina in a wall, one layer being weldable. Further the nodes joining the members may, as for the helmet described above, be distributed at different positions for different pairs of joined members, so that the nodes along one side of a member are longitudinally offset from the nodes on the other side of that member, so that air flow through the inflated article (in the event of an impact) must take a convoluted path, increasing the rigidity and resistance to the impact.

Claim 1:
An inflatable helmet (<NUM>) comprising a plurality of elongate members (<NUM>, <NUM>), each elongate member (<NUM>, <NUM>) comprising at least one chamber wall (<NUM>, <NUM>) defining an inflatable chamber (<NUM>);
wherein at least two adjacent elongate members (<NUM>, <NUM>) are in fluid communication with each other; and
wherein the plurality of elongate members (<NUM>, <NUM>) is inflatable so as to adjust the inflatable helmet from a collapsed state to an inflated state, characterised in that in the inflated state the at least two adjacent elongate members (<NUM>, <NUM>) abut each other along at least a portion of their respective chamber walls (<NUM>, <NUM>).