SHOCK ABSORBER

摘要

A shock absorber includes a suction passage permitting flow only from a reservoir toward a compression-side chamber, a rectification passage permitting flow only from the compression-side chamber toward an extension-side chamber, and a variable valve permitting flow only from the extension-side chamber toward the reservoir. A large chamber as a compression-side pressure chamber communicating with the compression-side chamber and an outer periphery chamber as an extension-side pressure chamber communicating with the extension-side chamber are partitioned in the shock absorber by a free piston that moves slidably within a bottom member serving as a housing. A compression-side pressure-receiving area of the free piston is larger than an extension-side pressure-receiving area. Therefore, even in the uniflow shock absorber with the extension-side chamber and the compression-side chamber at equal pressures during the contraction operation, the damping force is reduced under conditions in which high frequency is input since the free piston moves downward.

主权项

1. A shock absorber comprising:
a cylinder which is filled with a fluid; a piston that is slidably inserted into the cylinder and partitions the inside of the cylinder into an extension-side chamber and a compression-side chamber; a piston rod that is connected at one end to the piston and projects at the other end toward the outside of the cylinder; a reservoir configured to compensate for a change in capacity in the cylinder accompanying an ingression and retraction of the piston rod into and out of the cylinder; a suction passage configured to permit only a flow of the fluid from the reservoir toward the compression-side chamber; a rectification passage configured to permit only a flow of the fluid from the compression-side chamber toward the extension-side chamber; a damping force adjusting part configured to permit only a flow of the fluid from the extension-side chamber toward the reservoir and be capable of changing a resistance applied to the flow of the fluid; a housing that has a pressure chamber therein; a free piston that is slidably inserted into the pressure chamber and forms an extension-side pressure chamber and a compression-side pressure chamber within the pressure chamber; and a spring element configured to position the free piston in a neutral position within the pressure chamber and exert a biasing force to suppress displacement of the free piston from the neutral position, wherein the extension-side chamber communicates with the extension-side pressure chamber so as to press the free piston in one sliding direction, and the compression-side chamber communicates with the compression-side pressure chamber so as to press the free piston in the other sliding direction, and a pressure-receiving area of the free piston upon which a pressure of the compression-side pressure chamber acts is larger than a pressure-receiving area of the free piston upon which a pressure of the extension-side pressure chamber acts.