Protective helmet with impact-absorbing layer

Abstract

A protective helmet can reduce the likelihood of a player sustaining a brain injury while engaging in a contact sporting event. The helmet can include a hard outer shell with exterior and interior surfaces. The helmet can include an impact-absorbing layer adjacent to the interior surface of the outer shell. The impact-absorbing layer can have a base layer and flexible raised portions extending from the base layer toward the interior surface of the outer shell. During a collision with another player, the flexible raised portions can topple over to allow the outer shell to rotate relative to the impact-absorbing layer. The flexible raised portions can topple over and increase the duration of a collision, thereby reducing the peak rotational acceleration experienced by the player's head's center of gravity and, in turn, reducing the likelihood of the player sustaining a brain injury from the collision.

What is claimed is: 
     
         1 . A protective helmet comprising:
 a hard outer shell comprising an exterior surface and an interior surface; and   an impact-absorbing layer adjacent to and conforming to the interior surface of the hard outer shell, the impact-absorbing layer comprising a base layer and a plurality of flexible raised portions extending from the base layer, wherein the plurality of flexible raised portions each has a base portion wider than an end portion, wherein the end portions of the flexible raised portions extend to and contact the interior surface of the hard outer shell, and wherein the plurality of flexible raised portions comprise a microcellular urethane foam having a density of about 1-30 pounds per cubic foot.   
     
     
         2 . The protective helmet of  claim 1 , wherein the microcellular urethane foam is a mechanically frothed microcellular urethane foam. 
     
     
         3 . The protective helmet of  claim 1 , wherein the microcellular urethane foam has a density of about 10-20, 10-18, or 12-18 pounds per cubic foot. 
     
     
         4 . The protective helmet of  claim 1 , wherein the plurality of flexible raised portions are each defined by a side angle, a top radius, and a base radius, and wherein the side angle is about 1-30, 10-20, or 15 degrees. 
     
     
         5 . The protective helmet of  claim 4 , wherein the base radius is about 0.005-1.5, 0.125-0.5, or 0.125-0.25 inches, and wherein the top radius is about 0.005-1.0, 0.125-0.5, or 0.125-0.25 inches. 
     
     
         6 . The protective helmet of  claim 1 , further comprising an adjustable suspension system comprising:
 an inner fabric layer configured to conform to a portion of a wearer's head; and   a plurality of tethers extending from the inner fabric layer to the outer shell to flexibly secure the fabric layer to the hard outer shell and to capture the impact-absorbing layer between the fabric layer and the hard outer shell, wherein the tethers are configured to allow the hard outer shell to rotate relative to the inner fabric layer during an impact event as one or more of the plurality of flexible raised portions topple over.   
     
     
         7 . The protective helmet of  claim 1 , further comprising an adjustable suspension system comprising:
 a first fabric layer configured to conform to a front portion of a wearer's head;   a second fabric layer configured to conform to a rear portion of the wearer's head, wherein the first fabric layer attaches to the second fabric layer at a first attachment point along a left side of the wearer's head and at a second attachment point along a right side of the wearer's head;   a tensioning strap extending from the first attachment point to the second attachment point and comprising a chin cup configured to be secured against a wearer's chin;   a plurality of tethers extending from the first and second fabric layers to the hard outer shell to flexibly secure the first and second fabric layers to the hard outer shell and to capture the impact-absorbing layer between at least one of the first and second fabric layers and the hard outer shell, wherein the plurality of tethers are configured to allow the hard outer shell to rotate relative to the first and second fabric layers during an impact event as one or more of the plurality of flexible raised portions topple over.   
     
     
         8 . The protective helmet of  claim 1 , wherein the base layer comprises an indentation on a bottom surface of the base layer beneath one of the plurality of flexible raised portions, wherein the indentation is configured to provide a cavity in the impact-absorbing layer to increase an initial compression rate of the flexible raised portion during an impact event. 
     
     
         9 . The protective helmet of  claim 8 , further comprising a vent extending through the impact-absorbing layer from a top surface of the impact-absorbing layer to the indentation on the bottom surface of the impact-absorbing layer, wherein compressing the flexible raised portion during an impact event collapses the raised portion downward into the cavity formed by the indentation thereby forcing air out of the cavity through the vent, the air capable of transporting heat and perspiration away from the player's head. 
     
     
         10 . The protective helmet of  claim 1 , wherein the end portions of the plurality of flexible are affixed to or captured by the interior surface of the hard outer shell. 
     
     
         11 . A protective helmet comprising:
 a hard outer shell comprising an exterior surface and an interior surface;   an adjustable suspension system comprising:
 a fabric layer configured to fit snugly over a portion of a wearer's head, the fabric layer being flexibly connected to the interior surface of the hard outer shell by two or more tethers, the fabric layer being connected to a chin cup by a tensioning strap, wherein tightening the tensioning strap simultaneously draws the chin cup against a wearer's chin and draws the fabric layer against the portion of the wearer's head; 
   an impact-absorbing layer captured between the fabric layer and the hard outer shell, wherein the impact-absorbing layer comprises a plurality of flexible raised portions extending outward from a base layer toward the interior surface of the hard outer shell, wherein the hard outer shell is configured to rotate relative to the fabric layer during an impact event as the flexible raised portions of the impact-absorbing layer topple over.   
     
     
         12 . The protective helmet of  claim 11 , wherein the impact-absorbing layer comprises a microcellular urethane foam. 
     
     
         13 . The protective helmet of  claim 12 , wherein the microcellular urethane foam has a density of about 10-20, 10-18, or 12-18 pounds per cubic foot. 
     
     
         14 . The protective helmet of  claim 11 , wherein the plurality of flexible raised portions each comprise a side angle, a top radius, and a base radius, and wherein the side angle is about 1-30, 10-20, or 15 degrees. 
     
     
         15 . The protective helmet of  claim 14 , wherein the base radius is about 0.005-1.5, 0.125-0.5, or 0.125-0.25 inches, and wherein the top radius is about 0.005-1.0, 0.125-0.5, or 0.125-0.25 inches. 
     
     
         16 . The protective helmet of  claim 11 , wherein the base layer comprises an indentation on a bottom surface of the base layer beneath one of the plurality of flexible raised portions, wherein the indentation is configured to provide a low density cavity in the impact-absorbing layer to increase an initial compression rate of the raised portion during an impact event. 
     
     
         17 . The protective helmet of  claim 11 , further comprising a vent extending through the impact-absorbing layer from a top surface of the impact-absorbing layer to the indentation on the bottom surface of the impact-absorbing layer, wherein compressing the raised portion during an impact event collapses the raised portion downward into a cavity formed by the indentation thereby forcing air out of the cavity through the vent, the air capable of transporting heat and perspiration away from the player's head. 
     
     
         18 . The protective helmet of  claim 11 , wherein end portions of the plurality of flexible raised portions are affixed to or captured by the interior surface of the hard outer shell. 
     
     
         19 . An impact-absorbing layer comprising:
 a base layer; and   one or more flexible raised portions extending from the base layer, each of the one or more flexible raised portions having a base portion wider than an end portion, the one or more flexible raised portions each being defined by a side angle, a top radius, and a base radius, wherein the side angle is about 10-20 degrees, wherein the base radius is about 0.05-1.0 inches, wherein the top radius is about 0.05-1.0 inches, wherein the base layer has a thickness of about 0.1-1.3 inches, and wherein the impact-absorbing layer comprises a microcellular urethane foam having a density of about 12-18 pounds per cubic foot.   
     
     
         20 . The impact-absorbing layer of  claim 19 , wherein the microcellular urethane foam is a mechanically frothed urethane foam formed by a manufacturing process comprising:
 casting a liquid froth onto a substrate;   heat curing the liquid froth to form a solid urethane foam; and   coating the solid urethane foam with a continuous skin comprising a thermoplastic elastomer.