Self-pumping hydropneumatic shock absorber

Abstract

Self-pumping hydropneumatic shock absorber with internal level control, with an oil-filled working cylinder under the pressure of gas cushions and with a damping piston, which is attached to the end of a hollow piston rod and can slide back and forth in the working cylinder, the hollow space in the piston rod serving as the pump space of a pump rod attached to the working cylinder. Oil is drawn from a reservoir space when the piston rod travels outward and into the working space when the piston rod travels inward, and where a control opening is provided in the pump rod to compensate for pressure differences between the working spaces. At least one throttle acting as a function of pressure is provided in the pump space between the high-pressure gas cushion and the low-pressure gas cushion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross section of a self-pumping hydropneumatic shock absorber with internal level control; and

FIGS. 2-10 show cross sections of various embodiments of a throttle in isolation.

Claims

1. A self-pumping hydropneumatic shock absorber comprising: a working cylinder having a working space filled with hydraulic oil;a hollow pump rod fixed coaxially in the working cylinder;a high pressure chamber containing hydraulic oil and a high pressure gas cushion;a low pressure chamber containing hydraulic oil and a low pressure gas cushion;a damping piston which is movable in the working cylinder, the damping piston being attached to the end of a hollow piston rod which can slide on the pump rod, the piston drawing oil from at least one of the chambers into the working space when the piston rod travels outward, and pumping oil from the working space into at least one of the chambers when the piston rod travels inward;a discharge bore in the pump rod to compensate for pressure differences between the working spaces; anda pump space between the between the high pressure chamber and the low pressure chamber, the pump space having a throttle which acts as a function of pressure difference between the chambers.

2. The self-pumping hydropneumatic shock absorber of claim 1 further comprising a slide element which is movable in the pump space as a function of pressure difference between the chambers, the throttle being provided in the slide element.

3. The self-pumping hydropneumatic shock absorber of claim 2 wherein the slide element is biased toward the high pressure chamber.

4. The self-pumping hydropneumatic shock absorber of claim 3 further comprising a spring which biases the slide element toward the high pressure chamber, the spring comprising at least one of a mechanical spring and a gas spring.

5. The self-pumping hydropneumatic shock absorber of claim 2 wherein the slide element slides against an inside wall of the pump space, the slide element carrying a seal which exerts a sealing action against the inside wall.

6. The self-pumping hydropneumatic shock absorber of claim 2 wherein the slide element slides against an inside wall of the pump space, the inside wall having an axial stop which limits movement of the slide element.

7. The self-pumping hydropneumatic shock absorber of claim 2 wherein the throttle is blocked as a function of movement of the slide element.

8. The self-pumping hydropneumatic shock absorber of claim 7 wherein the throttle comprises a throttle bore, the shock absorber further comprising a conical element which is received in the throttle bore to block the throttle.

9. The self-pumping hydropneumatic shock absorber of claim 8 wherein the conical element is provided with a bypass groove which allows a minimal oil flow when the conical element is received in the throttle bore.

10. The self-pumping hydropneumatic shock absorber of claim 2 wherein the pump space has an inside wall provided with at least one control opening communicating with said low pressure chamber, said slide element being movable to cover at least one said control opening and thereby at least partially block communication between said high pressure chamber and said low pressure chamber.

11. The self-pumping hydropneumatic shock absorber of claim 2 wherein said slide element comprises a check valve which permits flow from said low pressure chamber when said pump rod is extended.