Adjustable hydraulic damper

Abstract

An adjustable hydraulic damper involves a piston member operating within a hydraulic cylinder where the hydraulic cylinder wall is adjustably deformed to vary the annular space between a piston head and the inside cylinder wall through which hydraulic fluid must pass. The wall of the cylinder is adjustably deformed through an annular ramp formed circumferentially about the outside of the cylinder and having an angled bearing surface. A compression nut, having an angled inside circumferential surface, threadingly engages the outside of the cylinder, wherein rotation of the compression nut causes its angled inside surface to bear on the ramp of the cylinder wall, thereby producing a local, uniform, annular deformation of the inside surface of the cylinder wall. The amount of deformation, and thus the flow of fluid through the annular space, is adjustable by rotation of the compression nut. For bi-directional damping, with two opposing piston heads on the piston member, each piston head utilizes a separate compression nut. In such form, each piston head also includes an internal valve, formed of a plurality of longitudinal interior passageways valved by a flexible baffle, to permit free flow of fluid through the piston head not directly involved in the damping action. An accumulator, in the form of an annular foam ring, is positioned on the piston member in the low pressure region between the first piston head and the opposing second piston head to provide piston rod volume compensation.