Method for reducing rotational acceleration during an impact to an outside surface of protective headgear

Abstract

A method for reducing rotational acceleration during an impact to an outside surface of protective headgear involves positioning a body between a head of a person and an inside top surface of the protective headgear. The body has a first face and a second face, with the first face providing a slippery exterior surface. Sliding movement along this slippery exterior surface is used to dissipate kinetic energy. In a first embodiment, a head of a person slides along the slippery exterior surface. In a second embodiment, the inside surface of the protective headgear slides along the slippery exterior surface. In a third embodiment, a helmet liner (with the head of a person positioned within it) slides along the slippery exterior surface.

What is claimed is: 
     
         1 . 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;   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.   
     
     
         2 . The method of  claim 1 , wherein the body has impact absorbing properties. 
     
     
         3 . The method of  claim 2 , wherein the body is an open-celled polymer foam. 
     
     
         4 . The method of  claim 1 , wherein the slippery exterior surface is a polymer plastic layer on the first face. 
     
     
         5 . The method of  claim 1 , wherein the body is held in position within the protective head gear by mechanical fasteners. 
     
     
         6 . The method of  claim 5 , wherein the mechanical fasteners are hook and loop tape fasteners. 
     
     
         7 . The method of  claim 1 , 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. 
     
     
         8 . The method of  claim 1 , 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. 
     
     
         9 . The method of  claim 8 , 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. 
     
     
         10 . The method of  claim 8 , wherein the body is a helmet liner. 
     
     
         11 . The method of  claim 1 , 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. 
     
     
         12 . The method of  claim 11 , 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.