Protective helmet with multiple energy management liners

Abstract

A helmet for rotational energy management can include an outer energy management layer comprising an outer surface and an inner surface opposite the outer surface. The inner surface can comprise a first slidable finish comprising a first glaze comprising a thickness less than or equal to 2 millimeters (mm). An inner energy management layer can be disposed within the outer energy management layer and further comprise an outer surface oriented towards the outer energy management layer and an inner surface opposite the outer surface. The outer surface can comprise a second slidable finish that directly contacts the first slidable finish. The second slidable finish can comprise a second glaze comprising a thickness less than or equal to 2 mm. A space between the first slidable finish and the second slidable finish can be devoid of a lubricant and devoid of any interstitial slip layer.

What is claimed is: 
     
         1 . A protective helmet for rotational energy management, comprising:
 an outer energy management layer comprising a first material, a first outer surface, and a first inner surface opposite the first outer surface, the first inner surface comprising a first slidable finish, the first slidable finish comprising a first glaze of the first material such that the first slidable finish is part of and not removable from the outer energy management layer; and   an inner energy management layer disposed within the outer energy management layer and comprising a second material, a second outer surface oriented towards the outer energy management layer, and a second inner surface opposite the second outer surface, the second outer surface comprising a second slidable finish that contacts the first slidable finish, the second slidable finish comprising a second glaze of the second material such that the second slidable finish is part of and not removable from the inner energy management layer.   
     
     
         2 . The protective helmet of  claim 1 , wherein:
 the first glaze comprises a thickness less than or equal to 1 millimeter (mm), and   the second glaze comprises a thickness less than or equal to 1 mm.   
     
     
         3 . The protective helmet of  claim 1 , wherein the first slidable finish and the second slidable finish each comprise a surface texture skewness of less than or equal to 1 mm. 
     
     
         4 . The protective helmet of  claim 1 , wherein:
 the outer energy management layer comprises expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), or expanded polyolefin (EPO),   the first glaze comprises EPS, EPP, EPU, or EPO,   the inner energy management layer comprises EPS, EPP, EPU, or EPO, and   the second glaze comprises EPS, EPP, EPU, or EPO.   
     
     
         5 . The protective helmet of  claim 1 , wherein the first slidable finish is configured to directly mate with the second slidable finish to form a low friction interface between the first inner surface and the second outer surface. 
     
     
         6 . The protective helmet of  claim 1 , wherein the outer energy management layer comprises a first lateral side and a second lateral side, and
 wherein the second outer surface extends continuously from the first lateral side to the second lateral side of the outer energy management layer.   
     
     
         7 . The protective helmet of  claim 1 , further comprising:
 an outer shell, the outer energy management layer disposed within the outer shell and the first outer surface oriented towards the outer shell.   
     
     
         8 . A protective helmet for rotational energy management, comprising:
 an outer energy management layer comprising a first material, a first outer surface, and a first inner surface opposite the first outer surface, the first inner surface comprising a first slidable finish, the first slidable finish being part of and not removable from the outer energy management layer; and   an inner energy management layer disposed within the outer energy management layer and comprising a second material, a second outer surface oriented towards the outer energy management layer, and a second inner surface opposite the first outer surface, the second outer surface comprising a second slidable finish that contacts the first slidable finish, the second slidable finish being part of and not removable from the inner energy management layer.   
     
     
         9 . The protective helmet of  claim 8 , wherein:
 the first slidable finish comprises a first glaze comprising a thickness less than or equal to 2 mm, and   the second slidable finish comprises a second glaze comprising a thickness less than or equal to 2 mm.   
     
     
         10 . The protective helmet of  claim 9 , wherein:
 the outer energy management layer comprises EPS, EPP, EPU, or EPO,   the first glaze comprises EPS, EPP, EPU, or EPO,   the inner energy management layer comprises EPS, EPP, EPU, or EPO, and   the second glaze comprises EPS, EPP, EPU, or EPO.   
     
     
         11 . The protective helmet of  claim 8 , wherein the first slidable finish and the second slidable finish each comprise a surface texture skewness of less than or equal to 1 mm. 
     
     
         12 . The protective helmet of  claim 8 , further comprising:
 an outer shell, the outer energy management layer disposed within the outer shell and the first outer surface oriented towards the outer shell.   
     
     
         13 . The protective helmet of  claim 8 , wherein the first slidable finish is configured to directly mate with the second slidable finish to form a low friction interface between the first inner surface and the second outer surface. 
     
     
         14 . The protective helmet of  claim 8 , wherein the outer energy management layer comprises a first lateral side and a second lateral side, and
 wherein the second outer surface extends continuously from the first lateral side to the second lateral side of the outer energy management layer.   
     
     
         15 . A protective helmet for rotational energy management, comprising:
 an outer energy management layer comprising a first material, a first outer surface, and a first inner surface opposite the first outer surface, the first inner surface comprising a first slidable finish, the first slidable finish being part of and not removable from the outer energy management layer; and   an inner energy management layer disposed within the outer energy management layer and comprising a second material, a second outer surface oriented towards the first outer energy management layer, and a second inner surface opposite the second outer surface, the second outer surface comprising a second slidable finish that contacts the first slidable finish, the second slidable finish being part of and not removable from the inner energy management layer.   
     
     
         16 . The protective helmet of  claim 15 , wherein:
 the first slidable finish comprises a first glaze comprising a thickness less than or equal to 2 mm; and   the second slidable finish comprises a second glaze comprising a thickness less than or equal to 2 mm.   
     
     
         17 . The protective helmet of  claim 16 , wherein:
 the outer energy management layer comprises EPS, EPP, EPU, or EPO,   the first glaze comprises EPS, EPP, EPU, or EPO,   the inner energy management layer comprises EPS, EPP, EPU, or EPO, and   the second glaze comprises EPS, EPP, EPU, or EPO.   
     
     
         18 . The protective helmet of  claim 15 , wherein the outer energy management layer comprises a first lateral side and a second lateral side, and
 wherein the second outer surface extends continuously from the first lateral side to the second lateral side of the outer energy management layer.   
     
     
         19 . The protective helmet of  claim 15 , wherein a space between the first slidable finish and the second slidable finish is devoid of a lubricant and devoid of any interstitial slip layer to facilitate relative movement between the first slidable finish and the second slidable finish at a time of impact. 
     
     
         20 . The protective helmet of  claim 15 , further comprising:
 an outer shell, the outer energy management layer disposed within the outer shell and the outer surface of the outer energy management layer oriented towards the outer shell.