US 6,202,993 B1Granted

Self-pumping hydropneumatic shock strut with internal level regulation

AssigneeMannesmann Sachs AG

InventorsBernd Wilms, Holger Kirchner, Achim Meier

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Abstract

Self-pumping hydropneumatic shock strut with internal level regulation for motor vehicles with a work cylinder which is filled with oil and acted upon by pressure by at least one gas cushion arranged in a high-pressure chamber which acts as a spring. The work cylinder is divided into two work spaces by a work piston carried by a hollow piston rod. The work piston has a piston pump which is driven by the spring movements and delivers oil from a low-pressure chamber in the work space connected with the high-pressure chamber. The pump cylinder of the piston pump is formed by the hollow piston rod. A hollow pump rod which is fastened to the work cylinder and carries a suction valve at its front end penetrates into the piston rod and the bore of the hollow pump rod is connected with the low-pressure chamber. A regulating opening of the pump rod is closable as a function of the position of the work piston in the work cylinder and connects the work space connected with the high-pressure chamber with a regulating channel having a choke and opening into the low-pressure chamber. The piston pump is provided with an overload valve in which the suction valve is incorporated.

Claims6

Dependent claims

A self-pumping hydropneumatic shock strut with internal oil level regulation, comprising:

a high-pressure chamber and a low-pressure chamber arranged in said shock strut;
a work cylinder filled with oil;
a work piston connected at an end of a hollow piston rod and slidably inserted in said work cylinder for dividing said work cylinder into a first work space and a second work space, said first work space operatively connected with said high-pressure chamber;
a piston pump operatively connected in said piston rod for delivering oil from said low-pressure chamber into said first work space, said piston pump comprising a pump cylinder formed by said hollow piston rod and a hollow pump rod having a first end fixed relative to said work cylinder and a second end comprising a suction valve inserted into said hollow piston rod, said pump rod having a bore there through connected with said low-pressure chamber so that said suction valve draws oil from said low-pressure chamber when said piston rod moves out of said work cylinder;
a regulating opening arranged through said pump rod so as to be closable by said piston rod as a function of a position of said piston rod in said work cylinder;
and
an overload valve operatively arranged in said piston pump for allowing oil to flow from said pump cylinder back toward said low-pressure chamber during an overpressure condition in said piston pump.

4 more elements

Dependencies are inferred from the claim text.