Patent ID: 7118099

Claim:
A self-pumping hydropneumatic spring strut with internal level control, said spring strut comprising: a high pressure chamber containing a gas cushion acting as a spring; a working cylinder which is filled with damping medium under pressure of said gas cushion; a working piston carried by a hollow piston rod and dividing said working cylinder into two working spaces, one of said working spaces being connected to said high pressure chamber to drive said piston under the pressure of said gas cushion, said piston having at least one non-return valve which permits flow from said one of said working spaces to the other of said working spaces; a low pressure chamber; a piston pump comprising a pump cylinder formed by said hollow piston rod and a hollow pump rod received in said piston rod, said pump rod having a bore with one end connected to said low pressure chamber and another end carrying a non-return valve which permits flow from said low pressure chamber into said hollow piston rod, and a cut-off orifice which connects said one of said working spaces to said low pressure chamber as a function of the position of said piston in said working cylinder; and an adjustable damping valve connected to a duct running from the other of said working spaces, said adjustable damping valve having an actuating element acted on by the pressure in said high pressure chamber and the pressure in said low pressure chamber.