Impact absorbing member and head protective member

Abstract

To provide an impact absorbing member for use in vehicles which has excellent energy absorbing capacity and is suitably adapted to absorb impact energy exerted on the head of an occupant in a vehicle cabin to reduce the head injury criteria value in the event of a vehicle collision. An impact absorbing member 1 is a plate-like impact absorbing member 1 made of rigid polyurethane foam and has recesses 3 formed in at least one surface thereof such that the recesses 3 are arranged in parallel along one direction. The shape of each recess 3 on the sectional view in the depth direction of the impact absorbing member 1 is a triangle to have sectional area decreasing toward the deepest point.

What is claimed is:  
     
         1 . An impact absorbing member made of rigid polyurethane foam which has a shape of a plate, and which has recesses in at least one surface thereof to be arranged in parallel along one direction, 
 wherein each recess is formed in such a shape as to have sectional area decreasing toward the deepest point.    
     
     
         2 . An impact absorbing member as claimed in    claim 1   , wherein the shape of each recess is acute at the bottom in the depth direction of the impact absorbing member.  
     
     
         3 . An impact absorbing member as claimed in    claim 2   , wherein the shape of each recess on a sectional view in the depth direction is a triangle.  
     
     
         4 . An impact absorbing member as claimed in any one of claims  1  through  3 , wherein the compressive stress of the rigid polyurethane foam is 3×10 −1  MPa or more.  
     
     
         5 . An impact absorbing member as claimed in any one of claims  1  through  4 , wherein the ratio of the volume of the recesses to the total of the volume of the rigid polyurethane foam portion and the volume of the recesses of the impact absorbing member is 3 to 40%.  
     
     
         6 . An impact absorbing member as claimed in    claim 5   , wherein the impact absorbing member has a shape lengthwise in one direction and wherein the recesses are formed in a portion other than both end portions of the impact absorbing member.  
     
     
         7 . An impact absorbing member as claimed in any one of claims  1  through  6 , wherein the impact absorbing member is used as a head protective member for use in vehicles in a state attached to a vehicle body or an interior equipment such as a head liner and a garnish.  
     
     
         8 . A head protective member which is formed in a lengthy rectangular shape and is constituted of a rigid polyurethane foam having hardness of 0.3 MPa or more, 
 wherein the thickness of the head protective member is 15 to 25 mm, and the effective width of portions mainly absorbing impact is 30 to 40 mm.    
     
     
         9 . A head protective member as claimed in    claim 8   , wherein said member has a HIC value of 800 or less.  
     
     
         10 . A head protective member as claimed in    claim 8    or    9   , having a slit formed by hollowing in the depth direction to extend in the longitudinal direction, wherein the sum of widths of solid portions other than said slit is set to be 30 to 40 cm.  
     
     
         11 . A head protective member as claimed in    claim 10   , wherein the width of the slit is preferably 5 to 20 cm.  
     
     
         12 . A head protective member as claimed in    claim 10    or    11   , wherein the hardness of the material constituting the head protective member is 1.2 to 1.6 MPa.  
     
     
         13 . A head protective member as claimed in    claim 8    or    9   , wherein the head protective member has a plate-like body without having a slit formed by hollowing in the depth direction.  
     
     
         14 . A head protective member as claimed in    claim 13   , wherein the hardness of the material constituting the head protective member is 1.0 to 1.4 MPa.  
     
     
         15 . A head protective member as claimed in any one of claims  8  through  14 , wherein the head protective member is used in a vehicle in a state attached to a vehicle body or an interior equipment such as a head liner and a garnish.