US 7,320,388 B2
Stroke dependent damping
Simon A de Molina, Marche-les-Dames (Belgium)
Assigned to Tenneco Automotive Operating Company Inc., Lake Forest, Ill. (US)
Filed on Sep. 15, 2003, as Appl. No. 10/662,547.
Prior Publication US 2005/0056501 A1, Mar. 17, 2005
Int. Cl. F16F 9/50 (2006.01)
U.S. Cl. 188—287  [188/281] 10 Claims
OG exemplary drawing
 
1. A two-stage shock absorber comprising:
a pressure tube defining a chamber;
a piston rod assembly disposed within said chamber;
a valve assembly fixably attached to said piston rod assembly and slidably engaging said pressure tube within said chamber, said valve assembly dividing said chamber into an upper and a lower working chamber, said valve assembly providing a first and a second fluid flow path between said upper and lower working chambers completely through said valve assembly, said first and second flow paths of said valve assembly being totally separate from one another; and
a sleeve slidably disposed on said piston rod assembly, said piston rod assembly defining a passage and a plurality of holes through said piston rod assembly, the plurality of holes being arranged in a helical spiral formation to create a third separate and distinct flow path extending between said upper and lower working chambers, said sleeve being operable to progressively close said third flow path by sequentially covering said plurality of holes when movement of said piston rod assembly exceeds a specified distance, said progressive closing of said third flow path providing a progressively higher resistance to the movement of said piston rod assembly, said sleeve being operable to simultaneously cover all of said plurality of holes to fully close said third flow path.