Patent ID: 6390257
Filing Date: 2002-05-21
Classification: F16F

Abstract:
Suspension damper for an automotive suspension system comprising a housing filled with damping fluid, a piston assembly slidable within said housing, said housing and said piston assembly being movable relative to one another in a rebound direction and in a compression direction, said piston assembly including a piston plate having a first set of openings, a wall defining a recess communicating said first set of openings with one another and terminating in a rim, a second set of openings, a first valve assembly including a valve disc movable between a closed condition engaging said rim to close said first set of openings and an open condition at least partially disengaged from said rim to open said first set of openings, said first valve assembly being in said closed condition when the piston assembly is moved in the compression direction and when the piston is moved in the rebound direction and the pressure differential across the piston plate is below a predetermined level, said first valve assembly being in said open position to permit communication through the first set of openings when the piston assembly is moved in the rebound direction and the pressure differential across said piston plate exceeds said predetermined level, a second valve assembly movable between a closed condition closing said second set of openings when the piston assembly is moved in the rebound direction and in the open condition when the piston assembly is moved in the compression direction, and a bypass passage bypassing said first valve assembly to permit restricted communication of damping fluid through said piston plate when the first valve assembly is in the closed condition and the pressure level across the piston plate is below the predetermined level, said bypass passage comprising a coined depression in the wall forming a valve seat for a valve disc of the first valve assembly to permit fluid flow therethrough under the valve disc with the first valve assembly in its closed condition, the coined depression having a continuously curved cross section.