To provide an oil damper in which damping force is switched by a pilot operation type main valve without using a logic valve, a high pressure in an oil chamber accumulated in the oil damper is used as pilot pressure to open the main valve, and the main valve returns by its self spring of the valve to close the main valve.
In an oil damper OD of uniflow type in which a valve generating damping force in a pipeline t1 communicating oil chambers Ra, Rb partitioned by a piston 7 fitted and inserted into an inner cylinder 1 slidably is arranged, the valve generating damping force consists of a pilot valve V1 and a main valve V2, and a high pressure Pa in the oil chamber Ra is introduced into the pilot valve V1 and the main valve V2. When the main valve V2 is opened, a high pressure Pa in the oil chamber Ra accumulated in the damper OD is used as a pilot pressure. When it is closed, it is returned by a self spring S of the main valve V2 to open and close the main valve 2 so that the pipeline t1 communicating with the oil chambers Ra, Rb is communicated and shut off.
SHIZUME TAKEJI
KITAMURA AKITOSHI
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