Special piston seal

Claim 1

In a shock absorber of the type including a cylindrical walled damping chamber for receiving a damping liquid and a piston dividing said chamber into a first and second portion and mounted for reciprocal movement within said chamber, means carried by said piston for controlling flow of damping liquid from said first portion of the chamber to said second portion during the movement of said piston within said chamber in one direction, said control means including: an annular valve seat on said piston; and annular valve member moved by fluid energy within said first chamber portion to and away from sealing engagement with said valve seat for controlling the flow of damping liquid during a first operational range from said first portion of said chamber to said second portion of said chamber; an annular seal carrier moved to and away from engagement with said valve seat by fluid energy during a second operational range of fluid flow from said first portion of said chamber to said second portion of said chamber, a resilient annular seal carried by said seal carrier positioned between said valve member and said seal carrier for sealing the flow of damping liquid between said valve member and said wall of said damping chamber, means defining flow passages between said valve seat and said annular seal carrier for restricting the flow of fluid from said first portion to said second portion of said chamber during said first operational range of fluid flow; a spring member for resiliently forcing said seal carrier in a direction toward said valve seat and for biasing said seal carrier against said valve seat during said first operational range of fluid flow from said first portion of said chamber to said second portion of said chamber, the improvement which comprises said annular seal being formed solely of a resilient material of a durometer sufficient to prevent extrusion thereof between said valve member and said wall of said damping chamber under maximum axial compression thereof between said valve member and said seal carrier, said annular seal having a radially outer peripheral surface portion of arcuate cross-sectional configuration disposed in sliding sealing relation with said wall of said damping chamber and axially opposed peripheral surface portions disposed in engagement with said valve member and said seal carrier respectively, said axially opposed peripheral surface portions having non-arcuate cross-sectional configurations which diverge axially inwardly at a rate less than the rate of radial inward divergenece of said radially outer peripheral surface portion so as to present a force per unit deflection due to compression by movement of said annular valve member during said first operational range of fluid flow which is less than the force per unit deflection due to compression of said seal in a radial direction and a total force less than the force exerted by said biasing spring member to hold said seal carrier against said valve seat.