Helmet sheer layer

Abstract

An apparatus and method for reducing tangential acceleration of a head with a helmet having a sheer release layer between the helmet and the head of the user. The release layer includes a low-friction surface against another surface such that the helmet shell acceleration does not translate to equal acceleration of the layer immediately adjacent to the head of the user. Coatings and materials are disclosed as well as padding and attachment materials and methods.

We claim: 
     
         1 . Protective gear for reducing tangential acceleration of a body during an impact to a surface, the protective gear comprising:
 an outer layer,   an inner layer,   an intermediate layer between the outer layer and the inner layer, the intermediate layer including a low-friction surface abutting the inner layer or the outer layer.   
     
     
         2 . The protective gear of  claim 1 , further comprising an impact layer having impact absorbing properties to absorb energy from normal forces. 
     
     
         3 . The protective gear of  claim 2 , wherein the impact layer comprises an open-celled polymer foam. 
     
     
         4 . The protective gear of  claim 1 , wherein the low-friction surface comprises a polymer plastic layer. 
     
     
         5 . The protective gear of  claim 1 , wherein the low-friction surface includes a low-friction coating on the intermediate layer. 
     
     
         6 . The protective gear of  claim 1 , wherein a body includes the intermediate layer and an impact layer, the body being held in position within the outer layer by mechanical fasteners. 
     
     
         7 . The protective gear of  claim 6 , wherein the mechanical fasteners are hook-and-loop tape fasteners. 
     
     
         8 . The protective gear of  claim 6 , wherein the protective gear is a helmet and the body includes a first face being the low-friction surface and a second face positioned against an inside top surface of the helmet and a wearer's head slides along the slippery exterior surface on the first face. 
     
     
         9 . The protective gear of  claim 6 , wherein the protective gear is a helmet and the body includes a first face being the low-friction surface and a second face of the body is positioned against the head and an inside top surface of the protective headgear slides along the slippery exterior surface on the first face. 
     
     
         10 . The protective gear of  claim 9 , wherein the body is secured to a portion of the inside top surface that does not directly face the head, with sliding occurring on that portion of the inside top surface that is directly facing the head. 
     
     
         11 . The protective gear of  claim 9 , wherein the body is a helmet liner. 
     
     
         12 . The protective gear of  claim 6 , wherein the protective gear is a helmet and wherein a second face of the body is positioned against an inside top surface of the helmet and a helmet liner is position on the head and the head, covered by the helmet liner, slides along the low-friction surface of the intermediate layer. 
     
     
         13 . The protective gear of  claim 12 , wherein the body is secured to a portion of the inside top surface that does not directly face the head, with sliding occurring on that portion of the inside top surface that is directly facing the head. 
     
     
         14 . A method for reducing rotational acceleration during an impact to an outside surface of protective headgear, comprising:
 positioning a body between a head of a person and an inside top surface of a protective headgear, the body having a first face and a second face, the first face providing a slippery exterior surface; and   positioning the second face of the body against one of the head or the inside top surface of the protective headgear, with the slippery exterior surface on the first face engaging the other of the head or the inside top surface of the protective headgear, such that, upon impact, a sliding movement takes place along the slippery exterior surface of the first face.   
     
     
         15 . The method of  claim 14 , wherein the body has impact absorbing properties. 
     
     
         16 . The method of  claim 15 , wherein the body is an open-celled polymer foam. 
     
     
         17 . The method of  claim 14 , wherein the slippery exterior surface is a polymer plastic layer on the first face. 
     
     
         18 . The method of  claim 14 , wherein the body is held in position within the protective headgear by mechanical fasteners. 
     
     
         19 . The method of  claim 18 , wherein the mechanical fasteners are hook-and-loop tape fasteners. 
     
     
         20 . The method of  claim 14 , wherein the second face of the body is positioned against the inside top surface of the protective headgear and the head slides along the slippery exterior surface on the first face. 
     
     
         21 . The method of  claim 14 , wherein the second face of the body is positioned against the head and the inside top surface of the protective headgear slides along the slippery exterior surface on the first face. 
     
     
         22 . The method of  claim 21 , wherein the body is secured to a portion of the inside top surface that does not directly face the head, with sliding occurring on that portion of the inside top surface that is directly facing the head. 
     
     
         23 . The method of  claim 21 , wherein the body is a helmet liner. 
     
     
         24 . The method of  claim 14 , wherein the second face of the body is positioned against the inside top surface of the protective headgear and a helmet liner is position on the head and the head, covered by the helmet liner, slides along the slippery exterior surface on the first face. 
     
     
         25 . The method of  claim 24 , wherein the body is secured to a portion of the inside top surface that does not directly face the head, with sliding to occurring on that portion of the inside top surface that is directly facing the head. 
     
     
         26 . A helmet liner for a helmet having a shell, the helmet liner comprising:
 a liner body securable within the shell, the liner body comprising a low-friction layer and a fabric layer, the fabric layer abutting the low-friction layer, the fabric layer having a perimeter and a central portion, the central portion of the top fabric layer free to accommodate sliding movement relative to the low-friction layer.   
     
     
         27 . The helmet liner of  claim 26 , further comprising an impact absorbing bottom layer secured to the low-friction layer. 
     
     
         28 . The helmet liner of  claim 27 , wherein the fabric layer is secured on at least a portion of its perimeter to the low-friction layer. 
     
     
         29 . The helmet liner of  claim 26 , wherein the fabric layer is stretchable, such that the fabric layer accommodates increased sliding movement of the low-friction layer as the fabric layer stretches. 
     
     
         30 . The helmet liner of  claim 26 , wherein the fabric layer is capable of serving as a loop portion of a hook-and-loop fastener and mating with a hook portion of the hook-and-loop fastener for the purpose of being anchored to an interior surface of a helmet. 
     
     
         31 . The helmet liner of  claim 27 , wherein the bottom layer is a polymer foam. 
     
     
         32 . The helmet liner of  claim 26 , wherein the low-friction layer is a polymer plastic.