| 摘要 |
PROBLEM TO BE SOLVED: To achieve a stable damping force even at the moment of reversal of the stroke direction of a piston rod, in a hydraulic shock absorber with an adjustable damping force having a pilot type attenuation valve. SOLUTION: Pilot chambers 14, 26 are formed at the back of disc valve 11, 31 on extension and contraction sides. The damping force in the low speed region of the piston velocity is adjusted by pressure control valve 19, 31, and also the damping force in the high speed region of the piston velocity is adjusted by controlling the valve opening pressure of disc valve 11, 23 by varying the pilot pressure introduced to the pilot chambers 14, 23 from oil chamber 20, 32 through cutouts 21, 33 and orifice grooves 22, 34. As a result, the transmission of a sudden pressure variation to the pilot chambers 14, 26, at the time of change-over of the stroke direction of the piston rod 8, becomes less smooth due to the throttling effect of orifice grooves 22, 34 and the stable damping force can be attained in that the variation of the damping force owing to the influence of the rapid pressure fluctuation is suppressed.
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