Patent Publication Number: US-2012036619-A1

Title: Helmet

Description:
The present invention concerns a helmet comprising at least a rigid outer shell and an inner portion of energy absorbing material. Especially, the helmet is suitable for alpine sports, such as down hill skiing. 
     BACKGROUND ART 
     When designing a helmet certain safety factors are taken into account, such as energy absorbing ability, penetration resistance and weight. The challenge when designing a safe and comfortable helmet is to make it as light weight as possible while achieving a high energy absorbing ability and a high level of penetration resistance. 
     Many helmet manufacturers reinforce the outer shell of their helmets with laminated glass or carbon fibres in order to improve the safety characteristics of the helmet while lowering the weight of the helmet. See for example EP 1 125 513 where a hardened and integrally assembled net or sheet member is used. 
     SUMMARY OF THE INVENTION 
     The main object of the present invention is to reduce the weight of a helmet. The weight of the helmet is an important factor when it comes to the severity of, for example, skull and neck injuries due to a crash. In order to achieve a lighter helmet at least an upper portion of the rigid outer shell may have a thickness of 0.01-4 mm, preferably 0.1-1.0 mm, especially if the material of the outer shell is for example ABS, polycarbonate, lexan or the like. Other materials are also conceivable. 
     An advantage of using a thinner rigid outer shell at least partially in the helmet is that it will absorb more shock energy due to partial collapsing of the thin rigid outer shell in a crash. Another advantage is that due to the partial collapsing of the outer shell bouncing of the helmet against the hit surface is reduced or even prevented. 
     Another object of the present invention is to improve the protection against penetration, which needs to be compensated for at the thin rigid outer shell. A solution is to provide a coated net, a coated woven or coated nonwoven material in the helmet, at least at the thin rigid outer shell, which is designed to withstand penetration of rocks, stones, branches and other objects that one may encounter in an action sport context and prevent that the object penetrates further through an inner portion of energy absorbing material of the helmet. Thus, if the present invention for penetration protection is combined with a thinner outer shell many advantages are achieved. The helmet may comprise more than one layer of outer shell and more than one layer of energy absorbing material. 
     Preferably the coated net, woven or nonwoven material extends over at least the portion with the thin rigid outer shell but may extend over the whole area of the helmet. The coated net, woven or nonwoven material may preferably be of unlaminated and/or unhardened fibres of, for example, glass, carbon or aramid, so that it keeps its soft, textile like properties. The coating may preferably be a silicon carbide or any material that will more or less lock the fibres so that the fibres will not easily separate when an object, like a stone, is on the way to penetrate the material layer. 
     The coating locks the fibres in the net, woven or nonwoven material so that the fibres will not separate enough to allow an object to penetrate the material layer on impact. The coated net, woven or nonwoven material is preferably arranged in a single-layer. The net may be connected at its nodes, for example, by means of knots, glue or in any other way. 
     The coated net, woven or nonwoven material may be loosely fitted in the helmet and attached at the rim of the helmet. Grooves corresponding to the design of the net may be provided on the outside surface of the inner portion of energy absorbing material for the net to rest in. According to another embodiment of the present invention the net or woven or nonwoven material may instead be glued, moulded by moulding the inner energy absorbing material directly into the rigid outer shell with the coated net, woven or nonwoven material in between, for example by means of in-moulding technique, or in any other way attached to the outer surface of the inner portion of energy absorbing material or to the inner surface of the outer shell. 
    
    
     
       SHORT DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described by means of a preferred embodiment as an example in connection with the drawings, in which: 
         FIG. 1  shows a helmet according to the invention with a portion of the rigid outer shell removed, and 
         FIG. 2  shows a cross sectional view of a portion of the helmet according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     According to  FIG. 1  a helmet  1  of the present invention is shown where a portion of a rigid outer shell  2  is taken away so that a coated net, woven or nonwoven material  3  is visible. The helmet  1  comprises at least a rigid outer shell  2  and an inner portion of energy absorbing material  4 . The outer shell  2  may comprise more than one layer, for example an outer polycarbonate layer and an inner glass fibre reinforced resin layer. Also the inner portion of energy absorbing material  4  may comprise more than one layer, for example a layer of honeycomb material, a layer of expanded polystyrene and a layer of soft foamed plastic. 
     At least a portion, preferably the upper portion, of the rigid outer shell is made up with a thin material layer having a thickness of 0.01-4 mm, preferably 0.1-1.0 mm, for example a rigid outer shell  2  of ABS, polycarbonate, lexan or alike may be used. Other materials are also conceivable. 
     Between the outer shell  2  and the inner portion of energy absorbing material  4  a coated net, woven or nonwoven material  3  is provided, at least partially, in order to catch any object that may penetrate the rigid outer shell  2  and prevent that the object penetrates further through the inner portion of energy absorbing material  4 . The coated net, woven or nonwoven material  3  compensates for the penetration protection loss at the portion having a thin rigid outer shell  2 . 
     The net or woven or nonwoven material  3  comprises unlaminated and/or unhardened fibres of, for example glass, carbon or aramid fibres, so that it keeps its soft, textile like properties. The coating is preferably a silicone carbide, for example Twaron®. The coated net, woven or nonwoven material is preferably arranged in a single-layer. 
     The form of the net  3  may be crossed or woven elongated fibres or threads of fibre or preferably elongated fibres or threads of fibre connected at its nodes by means of knots, glue or in any other way in order to lock the connection. The size of the net  3  may, for example, be 1-10 mm×1-10 mm, preferably 5×5 mm. The threads or fibres are not required to cross each other perpendicularly but can show squares, rhombs, rectangles and so on. 
     There are different conceivable ways of providing the coated net, woven or nonwoven material  3  in the helmet  1 . According to a first embodiment the coated net, woven or nonwoven material  3  is loosely fitted except along its edges where it is fixedly attached either in the outer shell  2  or in the inner portion  4 . If the coated net, woven or nonwoven material  3  cover all the area of the helmet  1  the coated net, woven or nonwoven material  3  is preferably attached along the rim of the helmet  1 . Grooves (not shown) corresponding to the design of the net  3  may be provided on the outside surface of the inner portion of energy absorbing material  4  for the net  3  to rest in. 
     According to another embodiment of the present invention the coated net, woven or nonwoven material may instead be glued, moulded or in any other way attached to the outer surface of the inner portion of energy absorbing material  4  or to the inner surface of the outer shell  2 . For example, the net or woven or nonwoven material  3  may be positioned at the inside surface of the outer shell  2  and then for example expanded polystyrene is moulded into the helmet  1  whereby the net or woven or nonwoven material  3  is moulded in between the outer shell  2  and the EPS or partially inside the EPS.