Shock absorber and compression valve assembly

Claim 1

In combination in a shock absorber, a pressure cylinder, a piston movable within said cylinder, valve means on said piston for controlling the flow of fluid through said piston between the opposite sides thereof, a reservior, a compression valve assembly for communicating fluid betwen said reservoir and said cylinder, said compression valve assembly comprising an annular base member disposed at the lower end of said pressure cylinder and defining a centrally located flow passage and an upwardly projecting circular valve seat circumjacent said passage, an annular valve plate arranged coaxially of said base member and having a central section extending downwardly toward said passage and a radially outwardly projecting section disposed above said valve seat being formed with a pair of radially spaced, concentrically oriented shoulder portions defining an annular chamber therebetween, a plurality of radially extending, circumferentially spaced recesses formed in the radially outermost of said shoulder portions providing flow paths communicating the lower end of said cylinder with said chamber, and at least one generally flat, ring-shaped valve element interposed between the upper side of said base member and the lower side of said radially outwardly projecting section of said valve plate, the lowermost portion of the radially innermost of said shoulders lying in a first radial plane and the lowermost portion of the radially outermost of said shoulders lying in a second radial plane spaced slightly above said first radial plane, whereby the upper side of said valve element is normally engaged with said radially innermost shoulder and is spaced below said radially outermost shoulder, with the lower side of said valve element normally being engaged with said valve seat, whereupon a predetermined increase in fluid pressure within the lower end of said cylinder results in said valve plate moving downwardly to a position wherein said lowermost portion of said outermost shoulder is engaged with the upper side of said valve element to slightly deform and effect a prestressing of said valve element, with a further increase in fluid pressure in said cylinder resulting in the inner peripheral portion of said valve element being biased downwardly away from engagement with said innermost shoulder to permit fluid to flow from said chamber through said flow passage into said reservoir, and upon upward movement of said piston within said cylinder, said valve plate and valve element will move upwardlY relative to said base member, resulting in the lower side of said valve element being disengaged from said valve seat to permit fluid to flow from said reservoir through said flow passage and around the outer periphery of said valve element and said valve plate into said cylinder.