Hydraulic damper of adjustable damping force type

Abstract

A hydraulic damper of adjustable damping force type includes a cylinder containing hydraulic liquid, a piston working in the cylinder and partitioning the interior thereof into two liquid chambers and having thereon a damping force generating mechanism, a piston rod connected to the piston and extending through one of the liquid chambers to the outside of the cylinder, a coaxial bore formed in the piston rod, a liquid passage communicating the two liquid chambers independently from the damping force generating mechanism and including at least a portion of the bore in the piston rod, an adjusting rod inserted into the coaxial bore and rotatable from the outside of the damper, and a rotary valve secured to the adjusting rod and having a plurality of circumferentially spaced and radially extending orifices for selectively changing the effective passage area of the liquid passage. A check valve on the inner circumference of the rotary valve rotates integrally therewith in the circumferential direction. Circumferentially spaced and radially extending orifices are formed in the check valve at the locations aligned and have orifices in the rotary valve with the passage areas smaller than corresponding orifices in the rotary valve. The check valve opens to permit the liquid flow through selected orifices during either one of contraction and extension strokes of the damper and closes during the other of the contraction and extension strokes of the damper.