INFLATABLE HELMET

Abstract

A helmet (10) which has a plurality of substantially longitudinal members (20) arranged side-by-side, the longitudinal members (20) being in fluid communication with each other. It has a first inflated state in which the longitudinal members (20) are distributed to form a substantially concave shape, and a second compressed state in which the longitudinal members (20) lie flat and substantially coincident against each other. Each longitudinal member (20) is separated from neighbouring longitudinal members (20) by a tubular connecting member (30) in a lattice configuration. The helmet (10) may be made of HDPE or nylon.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Entry of International

Application PCT/EP2015/069881 which claims priority to, and the benefit of, Great Britain Patent Application No. GB 1415362.1, filed Aug. 29, 2016, the entirety of which is hereby incorporated by reference as if fully set forth herein.

The present specification relates to inflatable helmets, particularly but not exclusively for bike riding and other leisure pursuits such as skateboarding.

Conventional hard cycling helmets give reasonable protection to a bike rider in the event of the rider hitting his head against a hard surface, such as when the rider falls or is thrown from their bike. However, such helmets are bulky, meaning that they can be inconvenient to carry around, and users may be tempted not to wear a helmet for this reason.

Various designs of inflatable helmets have been proposed, which can be deflated to a more compact and convenient form. However, such helmets may not offer the same protection as a hard helmet. A helmet protects the wearer both by spreading an impact over a larger area, and by absorbing energy by deformation. Some known inflatable helmets do not have sufficient rigidity, to spread an impact, and deform so easily, that very little energy is absorbed.

The object of the present invention is to provide a helmet than can be deflated to a more compact form which offers effective head protection.

According to the present invention, there is provided a helmet according to claim 1.

The invention will now be described, by way of example, with reference to the drawings, of which:

FIG. 1 is a perspective view of the helmet in a deflated state;

FIG. 2 is a longitudinal section of a longitudinal chamber;

FIG. 3 is a cross section of a longitudinal chamber;

FIG. 4 is a plan view of the helmet in a deflated state;

FIGS. 4a and 4b show a detail of FIG. 4 when the helmet is changing from the deflated state to the inflated state;

FIG. 5 is a transverse section of the helmet in an inflated state;

FIG. 6 is a diagrammatic view of a connecting strut in a deflated state;

FIG. 7 is a diagrammatic view of a connecting strut in an inflated state;

FIG. 8 is a cross section of a detail of the longitudinal chamber in a deflated state;

FIG. 9 is a partial sectional side elevation of a detail of the longitudinal chamber in a deflated state;

FIG. 10 is a cross section of a detail of the longitudinal chamber in an inflated state;

FIG. 11 is a plan view of the safety indicator;

FIG. 12 is a sectional view of the safety indicator; and

FIG. 13 is an underside plan view of the safety indicator.

Referring to FIG. 1, the helmet comprises a number of longitudinal chambers 20, arranged generally parallel to each other, and referring also to FIG. 5, a number of connecting struts 30, connecting each longitudinal chamber 20 to its neighbour.

Referring to FIGS. 2 and 3, each longitudinal chamber 20 comprises an inflatable chamber 22, surrounded by a flange 26 which lies in a vertical plane along the long axis of the longitudinal chamber 20. The inflatable chamber comprises two walls 23, 23′ which enclose a volume of air 24. The longitudinal chamber 20 generally curved or arcuate along its long axis; as can been seen in FIG. 2, both the inflatable chamber 22 and the flange may be curved, though to different degrees, and the lower surface of the inflatable chamber 22 and the upper surface of the inflatable chamber 22 may be curved to different degrees, and the lower surface of the flange 26 and the upper surface flange 26 may be curved to different degrees. The outer contour of the flange has a generally polar vector shape which adds strength to the curved air chamber it encompasses by way of this differential of vector space. The flange generally follows the upper surface (particularly when considered from a side profile of an individual longitudinal chamber—or connecting strut—but spaced from it by a generally constant distance), though for ease of manufacture, the top edge of the flange may be composed of flat edges whereas the shape of the longitudinal members may be a gradual curve.

Referring to FIG. 1 and FIG. 4, the longitudinal chambers 20 are here shown, though this number can of course be varied. The length and curvature of each longitudinal chamber 20 increases as one moves from the leftmost longitudinal chamber 20 to a maximum at the middle of the helmet 10 (in this specific case, the fourth longitudinal chamber 20), before decreasing both in length and curvature as one moves to the rightmost chamber. This gives the helmet a generally hemispherical shape, though flattened and elongated, in a similar way to a conventional hard cycling helmet.

Referring to FIGS. 4 and 5, the connecting struts 30 are also hollow, and are connected between the inflatable chambers 22 of each neighbouring longitudinal chamber 20, so that all the inflatable chambers 22 are in fluid communication. The connecting struts may also feature an outer-ridge or flange running along their length of the connecting struts' upper surface; a representative flange 27 is indicated in dotted lines in FIG. 5, which may be repeated for each strut. For both the longitudinal members and the connecting struts, such flanges may be present just on the upper surface, just on the lower surface, or on both upper and lower surfaces simultaneously.

In a deflated state, when there is little or no air in the helmet, the inflatable chambers 22 are each compressed to a generally flat state, lying in the same plane as each surrounding flange 26. Each longitudinal chamber 20 lies flat against the neighbouring longitudinal chambers 20, so that the whole structure of the helmet 10 has a flattened shape occupying a smaller volume.

When air is forced into the helmet, each inflatable chamber 22 expands, so that the walls 23, 23′ bow out around volume 24. The connecting struts 30 also expand, as will be described in greater details below. The width of each longitudinal chamber 20 increases, and the distance separating neighbouring longitudinal chambers 20 increases, so that the structure expands or concertinas out in one direction (i.e. perpendicular to the plane in which each flange lies). The resulting inflated shape is now similar to a traditional helmet and can be worn by a user.

Referring particularly to FIG. 5, during a fall or collision, a large component of the force experiences will usually be in a downward direction, radially inwards towards the head. The approximately oval shape of the inflatable chambers 22 allows further local expansion and deformation in the event of a force from such an impact, and the flanges may also flex and deform to provide further cushioning.

The positions of the connecting struts 30 are distributed over the length of the helmet, so that when considered from the side elevation, the number of connecting struts 30 that coincide is kept to a minimum; that is, connecting struts on either side of a longitudinal members ideally do not share a common axis (though their axes may be parallel). This staggered, offset or irregular distribution of the connecting struts increases the stability when external forces are applied. Ideally the position of the connecting struts 30 along the lengths of the longitudinal chambers 20 is generally alternated to give an elliptical-shaped distribution (or alternatively, a diamond-shaped or lattice-shaped distribution). This collar-beam rib acts not only as a structural support but also distributes and channels any loading throughout the helmet in a restricted manner, re-distributing any impact force with an even and fluid counter-reactive autonomy by way of the geometric ability of the design to fold without stress. This will also allow the helmet to fold down to a flatter configuration as it minimises the total thickness of material helping to reduce an agglomeration of mass at any one point along the length of the compressed helmet. It will be noted that the helmet ideally does not include a circumferential ring, so that the helmet is not constrained when being folded.

Each outer-ridge 26 will remain in a generally vertical position around each inflatable chamber 22. The strength of each longitudinal chamber 20 is increased by the addition of the outer-ridge 26, acting as a geometric structure to support and enclose the forces of the inflated chamber reducing the longitudinal chamber 20 from flexing.

The outer-ridge also reduces the surface area, and in the event of a fall or a crash, reduces the friction between the helmet and the ground or other surfaces, and thus prevents a sudden deceleration of the head which can put stress on the user's neck. The flange also protects the inflatable chambers from external abrasion during daily use.

Referring to FIGS. 6 and 7, each connecting strut 30 comprises a generally tubular wall 32 that extends between apertures 34 formed in the walls 23 of neighbouring inflatable chambers 22. The apertures 34 are rhombic or diamond-shaped. The connecting strut 30 may be formed with a crease of folds 37 in the flattened state to help achieve the rhombic cross section in the helmet's inflated state. When the helmet is in the uninflated, compressed state, the connecting strut 30 lies flat, with the wall 32 folded along two edges 35, 36 (extended between two opposite corners of the rhombus). In this state, the connecting strut 30 and the walls 23 of the inflatable chambers 22 all lie in parallel planes. Alternatively, the connecting strut may have a circular tubular section, or an elliptical, ovate or lenticular tubular section; equally, the apertures 34 may be circular, elliptical or lenticular, the connecting strut may have two fold lines 37 (conforming to a lenticular section) or no fold lines. A fold line or pair of fold lines may occur at the region where a flange or ridge runs. The absence of fold lines (and corners in the aperture) with elliptical shape eliminates weak points and seams.

As the helmet is inflated and the inflatable chambers 22 and the connecting struts 30 are filled with air, the connecting strut 30 expands to a more tubular shape, having a generally elliptical cross section (though the section could have straighter sections and corners, for example a rhombic shape, and the section can change along the length of the connecting strut). Thus forming a complex arrangement of structural supports interlinking the cross-fluted chambers to form a hollow geometric structure. The addition of the air effectively unfolds this structure creating a pre-stressed geometrically formed protective cage. At the same time, the distance between the walls 23 of the inflatable chambers 22 increases, and the angle that the connecting strut 30 makes with the walls 23 increases from 0° to closer to 45°, in the manner of a hinges, so that the structure as a whole, considered in plan acts like a network of folding parallelograms, this being illustrated in FIGS. 4a and 4b. The geometry of the inflatable chamber 22 and connecting struts 30 does not permit the walls 23 of the inflatable chambers 22 to remain perfectly flat, and the connecting strut 30 to fold into a rhombic cross section with perfectly flat sides, in the inflated state, from a perfectly flat folded structure in the uninflated state. Since the material of the helmet is chosen to ideally be flexible but not stretchable, when the connecting struts 30 are expanding, the walls 23 of the inflatable chambers 22 curve around the aperture 34, and the wall and edges of the connecting struts 30 will not be perfectly straight and flat. This generally elliptical or rhombic cross section provides a structural support and increases rigidness to transverse forces acting on the helmet.

Referring to FIGS. 8, 9 and 10, the shape of each inflatable chamber 22 can be constrained in the inflated position by internal bracing straps. A strap 38 is formed with each end attached to opposite walls 23, 23′ of an inflatable chamber 22 during manufacture. When the inflatable chamber 22 is in the uninflated state, the bracing strap is in a slack state, lying generally flat and in the plane of the flat walls 23, 23′, possibly arranged in a figure-of-eight loop. The length of the strap 38 is chosen such that when the helmet is filled with air and the inflatable chamber 22 inflates, the strap is drawn taut between the walls 23, 23′ as they separate at their midpoints (i.e. at the widest point when the inflatable chamber 22 is inflated). When the strap 38 reaches its maximum extension it constrains the inflatable chamber 22 from expanding further.

In general then, the structure of the helmet is a one where, considered in plan, the longitudinal members and connecting strut members expand from a deflated state where the longitudinal members and connecting strut members are lying approximately parallel state with a small total width, to an expanded lattice-type structure, with the longitudinal members still parallel, and the connecting strut members all inclined to the longitudinal members, to give the structure the required width. Ideally, the connecting strut members will all be inclined to the same degree, though also the lengths and/or angles of connecting strut members could be varied to creates different separations between longitudinal members or even cause the longitudinal members to diverge from a parallel arrangement. As well as having laterally non-aligned anchor or intersection points with the longitudinal members, the connecting strut members ideally alternate so that (as shown in FIGS. 4, 4a and 4b) some are oriented approximately 45° positively and others oriented 45° negatively in the inflated state although it will be appreciated that less ideally the connected struts could be all aligned identically.

The helmet is ideally composed of a single material made as a single integral part. The material is chosen such that ideally it does not stretch by more than approximately 5%, so that form is constrained so that, once inflated, it cannot deform (or balloon) too much, thus maintaining its shape and thereby providing an effective protective shell that can sustain suitable elongation-to-break tolerances. Suitable materials are high-density polyethylene (HDPE or PEHD), Nylon or material with similar properties, but can also be achieved by the use of carbon fibre, and rubber with an internal Kevlar, polyester or nylon weave. The material can be formed into the helmet shape either by printing or by other flat formed process, injection moulding, or by forming together flat elements and then bonding together. These materials also have a suitable tensile strength and resilience, without being brittle or liable to puncture, both under normal use, repeated inflation and deflation cycles, and in the event of an impact.

More stretchable material could be used, although it may be necessary to provide greater internal bracing (such as a polyester, nylon or carbon fibre woven or drop stitch bracing), which prevents over inflation and maintains the correct internal pressure.

Using these types of material for the helmet allows the helmet to be formed as a single-skinned shape (with a single continuous topological surface).

Typically, the flanges 26 the walls of the inflatable chambers 22 and connecting struts 30 comprise a single layer of material, formed as a single homogenous piece, at an approximately constant thickness of 0.7 to 1 mm. A suitable method of manufacturing the helmet is by 3D printing technique, for example fused deposition, forming the helmet in its compressed state, though other techniques such as selective laser sintering, stereo lithography and yet-to-be developed methods may be similarly employed.

The internal bracing straps can be formed simultaneously. This technique is particularly suitable for forming material to the required tolerance to produce opposite walls of the inflatable chamber 22 and the connecting strut 30 the walls that lie nearly flat against each other (and likewise between the neighbouring walls of the inflatable chambers 22 and the connecting strut 30) with little separation in the uninflated, compressed state, but still remain distinct and without the adjacent walls adhering to each other. The helmet could also be formed by injection moulding or printed in a state that isn't completely flat and compressed.

Ideally, an adjustable chin strap may be attached at two points on opposite sides of the helmets, so that the inflated helmet is held firmly on the user's head when in use, with lugs or fixing points formed in the helmet for this purpose.

The helmet is formed as a completely sealed unit with a valve that can be used to inflate the helmet. Typically, this will be a standard Schrader valve, a common component to cycling due to its reliability. It also means the helmet can be inflated with a normal standard bicycle pump.

An excessive amount of pressure applied to the helmet, either during its inflation, or as a result of a fall or impact against the helmet, can damage the material of the helmet, and possible lead to earlier, sudden and catastrophic failure, either during normal use or during an impact, so that the helmet is either rendered useless, or does not provide sufficient impact protection.

Referring to FIGS. 11 to 13, a safety indicator 40 is included at some location on the outside of the helmet, preferably near the inlet valve. A circular area 42 is included in the wall 23 of the helmet (typically on one of the side most inflatable chambers 22), the wall 23 in this area being flat on the outer surface of the wall 23, but slightly concave 43 on the inner surface, so that the material thickness of the wall at 44 decreases towards the centre of the circular area 42. At the centre of the circular area, a brightly coloured circular region 45 may be included on the outer surface. Rupture lines 46 extend around the circular region, and in a radial formation extending outwards from the circular region. A particularly thin weak point 48 may be included, for example in the centre of the circle.

The shape and thickness of the wall material at the circular area 42, and the configuration and depth of the rupture lines 46, is formed such that when a predetermined pressure is met or exceeded, the rupture lines and/or weak point will tear, and this tear will quickly spread along part of the rupture lines. When this has occurred, the rupture will be very evident since the brightly coloured circular region 45 will be ripped, distorted or not visible at all.

The necessary shape and thickness of the wall material at the circular area 42, and the configuration and depth of the rupture lines 46, may be determined by producing a range of configurations by varying the parameters of shape, thickness, configuration, depth etc for a particular material, and destructively testing each configuration until one is found that ruptures at the required pressure.

In addition to the absolute release valve a secondary release valve is incorporated into the pressurising valve as a ‘controlled release system’. This controls the maximum amount of air pressure allowed to enter the helmet, so protecting the structure from over inflation very precisely to within approximately plus or minus 8 psi of the maximum safety pressure. This valve will also allow the controlled and counter-reactive autonomous release of air during impact via the valves pre-primed and calibrated die-spring load release, thereby reducing impact force by diverting this force by way of this reactionary device, creating an anti-recoil energy absorption system. This also prevents absolute destruction of the unit by avoiding added stresses to occur during impact and thereby increasing the overall safety factor of the helmet.

Claims

1. A helmet, comprising:

having a plurality of substantially longitudinal members arranged side-by-side, the longitudinal members being in fluid communication with each other;

having a first inflated state in which the longitudinal members are distributed to form a substantially concave or dome shape;

having a second compressed state in which the longitudinal members lie flat and substantially coincident against each other.

2. A helmet according to claim 1 wherein each longitudinal member is separated from neighbouring longitudinal members by a connecting member in a lattice-like or a restricted configuration.

3. A helmet according to claim 2 wherein the connecting members include a flat rib or fin extending from the surface of the connecting member.

4. A helmet according to claim 2 wherein the connecting members have an elliptical section.

5. A helmet according to any of claims 2 to 4 wherein the intersection between connecting members on a longitudinal member are non-coincident when considered from the side.

6. A helmet according to claim 2 wherein the intersection between connecting members on adjacent longitudinal members are non-coincident when considered from the side.

7. A helmet according to claim 2 wherein the connecting members lie substantially parallel to the longitudinal members in the compressed state, but form an angle with the longitudinal members in the inflated state.

8. A helmet according to claim 7 wherein the angle the inflated state does not exceed 60 degrees.

9. A helmet according to claim 8 wherein the angle the inflated state does not exceed 45 degrees.

10. A helmet according to claim 1 wherein the longitudinal members and/or the connecting members have a generally elliptical, lenticular or rhombic shape that can folded flat in the compressed state.

11. A helmet according to claim 1 wherein the helmet is made of HDPE or nylon.

12. A helmet according to claim 1 wherein the helmet is fabricated using a 3D printing technique.

13. A helmet according to claim 12 wherein the 3D printing technique is fused deposition.

14. A helmet according to claim 12 wherein the 3D printing technique is selective laser sintering.

15. A helmet according to claim 12 wherein the 3D printing technique is stereo lithography.

16. A helmet according to claim 1 wherein the helmet includes an indicator showing the user when the helmet has been inflated to the correct pressure.

17. A helmet according to claim 1 wherein the helmet includes an indicator showing the user when the helmet is unsafe due to the pressure having been exceeded.