Foam cushion having a progressively increasing spring constant

Abstract

A foam member for use within a vehicle seat exhibits a progressive spring effect along a vertical section therethrough. Preferably, the vertical section has a top and a bottom, with a spring constant of the foam increasing from top to bottom. In another aspect of the invention, the foam member has a top and a bottom, and includes an upper layer at the top of the foam member, and a lower layer at the bottom of the foam member. The lower layer is configured to resist a load applied to the foam member more than the upper layer. At least one of the layers may include an upper surface having a vertical component, thereby imparting a contoured shape thereto.

1 . A foam cushion for use within a vehicle seat comprising: 
 a foam member;    a first foam portion at a top of a vertical section taken through said foam member, said first foam portion having a first spring constant; and    a second foam portion at a bottom of said vertical section, said second foam portion having a second spring constant greater than said first spring constant, such that said foam member exhibits a progressive spring effect along said vertical section.    
     
     
         2 . The foam cushion of  claim 1 , wherein said second foam portion has a higher density than said first foam portion.  
     
     
         3 . The foam cushion of  claim 1 , wherein said second foam portion has a higher firmness than said first foam portion.  
     
     
         4 . The foam cushion of  claim 1 , further comprising: 
 a third foam portion disposed along said vertical section between said first and second foam portions, said third foam portion having a third spring constant greater than said first spring constant and less than said second spring constant, such that said foam member exhibits a progressive spring effect along said vertical section from said top to said bottom.    
     
     
         5 . The foam cushion of  claim 1 , wherein said foam member comprises a plurality of layers bonded together to create a laminate.  
     
     
         6 . A foam cushion for use within a vehicle seat comprising: 
 a foam member having a top and a bottom, said top providing a load surface for a seat occupant;    an upper layer at said top of said foam member; and    a lower layer at said bottom of said foam member;    wherein said lower layer is configured to provide greater resistance to a vertical load applied to said foam member than said upper layer.    
     
     
         7 . The foam cushion of  claim 6 , further comprising: 
 a middle layer disposed between said upper and lower layers, wherein said middle layer is configured to provide less resistance to vertical load applied to said foam layer than said lower layer and more resistance than said upper layer.    
     
     
         8 . The foam cushion of  claim 7 , wherein at least one of said upper layer, said middle layer and said lower layer includes an upper surface having a vertical component.  
     
     
         9 . The foam cushion of  claim 8 , wherein said upper surface is characterized by a generally centrally located protuberance.  
     
     
         10 . The foam cushion of  claim 8 , wherein said upper surface is characterized by at least one generally laterally located protuberance.  
     
     
         11 . The foam cushion of  claim 6 , wherein said foam member is used as at least one of a vehicle seat cushion and a vehicle seat back.  
     
     
         12 . The foam cushion of  claim 6 , wherein said foam member integrally provides a vehicle seat cushion, vehicle seat side bolsters, and a vehicle seat front bolster.  
     
     
         13 . The foam cushion of  claim 6 , wherein said foam member integrally provides a vehicle backrest cushion, side supports, and a lumbar cushion.  
     
     
         14 . The foam cushion of  claim 6 , wherein said foam member is used as a vehicle seat headrest.  
     
     
         15 . The foam cushion of  claim 6 , wherein at least one of said upper and lower layers comprise one of a conventional urethane foam and a viscoelastic memory foam.  
     
     
         16 . A foam member for use within a vehicle seat comprising: 
 an upper layer having a first spring constant and a lower surface at least partially defining a first contour;    a lower layer having a second spring constant and an upper surface at least partially defining a second contour; and    a middle layer having a third spring constant greater than said first spring constant and less than said second spring constant, an upper surface at least partially defining a third contour complementary to said first contour, and a lower surface at least partially defining a fourth contour complementary to said second contour;    wherein said upper, lower and middle layers interlock such that said first contour mates with said third contour and said second contour mates with said fourth contour, and wherein said upper, lower and middle layers are bonded together to form said foam member.    
     
     
         17 . The foam member of  claim 16 , wherein at least one of said upper, lower and middle layers are provided by casting.