Patent ID: 8453807

Claim:
A hydraulic damper device for retarding movement of a movable member toward a stationary member, comprising: a cylinder adapted to be connected to one of the movable and stationary members, and having an inner cylindrical surface which surrounds an axis and which defines a receiving chamber therein, said receiving chamber extending along the axis to terminate at first and second end walls; an axially shiftable plug disposed in said receiving chamber and in slidable frictional engagement with said inner cylindrical surface to partition said receiving chamber into a liquid compartment filled entirely with liquid and an air compartment filled entirely with air; a piston disposed to be axially movable in said liquid compartment and having an outer peripheral surface which surrounds the axis, and which is configured to confront said inner cylindrical surface radially to divide said liquid compartment into plug-side and end-side sub-compartments, said piston having a primary passage which is fluidly communicated with said plug-side and end-side sub-compartments such that, as a result of an end-side bound liquid flow through said primary passage in a course of opening movement, said piston is moved from a most remote position to a closest position relative to said first end wall, and such that, in a course of retarding movement, said piston is moved from the closest position, where said piston is subject to a largest liquid pressure in said end-side sub-compartment, to the most remote position, said piston is subject to a smallest liquid pressure in said end-side sub-compartment; and a piston rod which has a connected end secured to said piston, and a shank extending from said connected end along the axis through said axially shiftable plug and said first end wall so as to permit said piston to proceed with the course of retarding movement such that, when said piston proceeds with the final stage of the retarding movement, said axially shiftable plug is urged to move towards said first end wall by virtue of an increased pressure in said plug-side sub-compartment resulting from an surge in a plug-side bound liquid flow from said end-side sub-compartment into said plug-side sub-compartment, wherein said shank of said piston rod is in slidable engagement with said axially shiftable plug and said first end wall and terminates at a pulled end which is disposed outwardly of said first end wall to be adapted to be connected to the other one of the movable and stationary member.