Velocity progressive valving

Abstract

A shock absorber has a valve assembly having a valve that is biased away from a valve body. A controlled restriction is defined between the valve and the valve body. During stroking of the piston of the shock absorber, the valve moves toward the valve body to close the restriction. The valve assembly can be used in the piston assembly, the base valve assembly or both.

What is claimed is: 
     
         1 . A shock absorber comprising:
 a pressure tube forming a working chamber;   a piston body disposed within said working chamber formed by said pressure tube, said piston body dividing said working chamber into an upper working chamber and a lower working chamber, said piston body defining a passage extending between said upper working chamber and said lower working chamber;   a piston rod attached to said piston body, said piston rod extending through one end of said pressure tube;   a first valve assembly engaging said piston body, said first valve assembly comprising:   a first biasing member engaging said piston body; and   a first valve engaging said first biasing member, said first valve moving axially with respect to said piston rod, said first biasing member urging said first valve away from said piston body.   
     
     
         2 . The shock absorber according to  claim 1 , wherein said first biasing member includes a disc spring. 
     
     
         3 . The shock absorber according to  claim 1 , wherein said first valve defines a valve orifice in communication with said passage in said piston body. 
     
     
         4 . The shock absorber according to  claim 1 , wherein said first valve and said piston body define a controlled restriction, said controlled restriction reducing in size when said piston body moves axially within said pressure tube. 
     
     
         5 . The shock absorber according to  claim 1 , wherein said first valve sealingly engages said pressure tube. 
     
     
         6 . The shock absorber according to  claim 1 , further comprising a first valve guide disposed between said piston rod and said first valve. 
     
     
         7 . The shock absorber according to  claim 6 , wherein said first biasing member is disposed between said piston rod and said first valve guide. 
     
     
         8 . The shock absorber according to  claim 1 , wherein an outer circumference of said first valve sealingly engages said piston body. 
     
     
         9 . The shock absorber according to  claim 1 , wherein the shock absorber further comprises a second valve assembly, said second valve assembly comprising:
 a second biasing member engaging said piston body;   a second valve engaging said second biasing member, said second valve moving axially with respect to said piston rod, said second biasing member urging said second valve away from said piston body.   
     
     
         10 . The shock absorber according to  claim 9 , wherein said first and second biasing members include a disc spring. 
     
     
         11 . The shock absorber according to  claim 9 , wherein each of said first and second valves define a valve orifice in communication with said passage in said piston body. 
     
     
         12 . The shock absorber according to  claim 9 , wherein each of said first and second valves and said piston body define a controlled restriction, each of said controlled restrictions reducing in size when said piston body moves axially within said pressure tube. 
     
     
         13 . The shock absorber according to  claim 9 , wherein each of said first and second valves sealingly engage said pressure tube. 
     
     
         14 . The shock absorber according to  claim 9 , further comprising a first valve guide disposed between said piston rod and said first valve and a second valve guide disposed between said piston rod and said second valve. 
     
     
         15 . The shock absorber according to  claim 14 , wherein said first biasing member is disposed between said piston rod and said first valve guide and said second biasing member is disposed between said piston rod and said second valve guide. 
     
     
         16 . The shock absorber according to  claim 9 , wherein an outer circumference of each of said first and second valves sealingly engages said piston body. 
     
     
         17 . The shock absorber according to  claim 1 , further comprising:
 a reserve tube surrounding said pressure tube to define a reserve chamber;   a base valve assembly disposed between said working chamber and said reserve chamber, said base valve assembly comprising:
 a base valve body defining a passage extending between said working chamber and said reserve chamber; 
 a second biasing member engaging said base valve body; and 
 a second valve engaging said second biasing member, said second valve moving axially with respect to said base valve body, said second biasing member urging said second valve away from said base valve body. 
   
     
     
         18 . The shock absorber according to  claim 17 , wherein said first and second biasing members include a disc spring. 
     
     
         19 . The shock absorber according to  claim 17 , wherein said first valve defines a first valve orifice in communication with said passage in said piston body and said second valve defines a second orifice in communication with said passage in said base valve body. 
     
     
         20 . The shock absorber according to  claim 17 , wherein said first valve and said piston body define a first controlled restriction, said first controlled restriction reducing in size when said piston body moves axially within said pressure tube, said second valve and said base valve body define a second controlled restriction, said second controlled restriction reducing in size when said piston body moves axially within said pressure tube. 
     
     
         21 . The shock absorber according to  claim 17 , wherein each of said first and second valves sealingly engage said pressure tube. 
     
     
         22 . The shock absorber according to  claim 17 , further comprising a first valve guide disposed between said piston rod and said first valve and a second valve guide disposed between said base valve body and said second valve. 
     
     
         23 . The shock absorber according to  claim 22 , wherein said first biasing member disposed between said piston rod and said first valve guide and said second biasing member disposed between said base valve body and said second valve guide. 
     
     
         24 . The shock absorber according to  claim 17 , wherein an outer circumference of said first valve sealingly engages said piston body and an outer circumference of said second valve sealingly engages said base valve body.