| 摘要 |
An object of the present invention is to generate a stable damping force and enhance durability of a main valve in a hydraulic shock absorber in which valve opening of the main valve is controlled by an inner pressure of a backpressure chamber. A first piston 3 and a second piston 4 coupled to a piston rod 10 are fitted in a cylinder 2 such that a piston chamber 2 C is defined between the first and second pistons 3, 4 . An extension-side main valve 18 and a compression-side main valve 23 are provided in the piston chamber 2 C. Valve opening of the main valves is controlled by an extension-side backpressure chamber 19 and a compression-side backpressure chamber 24 . A compression-side check valve 13 and an extension-side check valve 16 are provided at the first piston 3 and the second piston 4 . During an extension stroke of the piston rod 10 , the compression-side check valve 13 is closed, whereby action of a pressure of a cylinder upper chamber 2 A on the compression-side main valve 23 is prevented. During a compression stroke of the piston rod 10 , the extension-side check valve 16 is closed, whereby action of a pressure of a cylinder lower chamber 2 B on the extension-side main valve 18 is prevented. Accordingly, it is possible to generate a stable damping force, and enhance durability of the extension-side main valve 18 and the compression-side main valve 23.
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