Patent ID: 7344127

Claim:
A self-pumping hydropneumatic spring strut with an internal level control, comprising: a cylinder defining a high-pressure chamber and a low-pressure chamber, both chambers being at least partially filled with oil, the high-pressure chamber further comprising a gas cushion acting as a spring element; an axially movable hollow piston rod arranged within the cylinder and carrying a working piston separating two working spaces arranged in the cylinder, one of the working spaces being connected to the high-pressure chamber; a piston pump driven by movements of the spring element for conveying oil from the low-pressure chamber to the working space connected to the high-pressure chamber, the piston pump having a first flow connection which connects the high-pressure chamber to the low-pressure chamber; and an adjustable valve arranged in a second flow connection between the high-pressure chamber and the low-pressure chamber, the second flow connection being separate from the first flow connection, the valve opening as a function of pressure in the high-pressure chamber to allow the oil to pass from the high-pressure chamber to the low-pressure chamber.