Patent ID: 8052128

Claim:
A Self-pumping hydropneumatic spring strut with internal leveling control for vehicles, comprising: an outer tube; a work cylinder arranged concentrically with the outer tube, the work cylinder defining a high-pressure work space in the work cylinder and a second work space, the high-pressure work space is under pressure by at least one gas cushion which is arranged in a high-pressure chamber and acts as a spring, the second work space is located on a piston rod guide side of the work cylinder; and a piston supported by a hollow piston rod and axially displaceable in the work cylinder in a sealed manner, the piston forming part of a piston pump which is driven by movement of the vehicle and is configured to pump oil out of a low-pressure chamber into a work space connected to the high-pressure chamber, the piston pump comprises a pump rod and a pump cylinder which is formed by the hollow piston rod, the high-pressure chamber is configured to be connected to the atmosphere by a flow connection arranged in the piston rod guide and has a closing element, wherein the piston rod is sealed in the piston rod guide by at least two seals which are arranged one behind the other axially, and a flow connection extends from between two adjacent seals of at least two seals into the low-pressure chamber, and the flow connection is acted upon by a check valve which passes damping medium only in direction of the low-pressure chamber.