| 摘要 |
Provided is a hydraulic shock absorber enabling an increase in a variable range of both damping forces produced in an extension stroke and a compression stroke thereof. A cylinder ( 1 ) filled with hydraulic oil is divided into first and second oil chambers ( 101 ) and ( 102 ) by a piston ( 2 ), and a main valve ( 4 ) is disposed in a main passage ( 81 ) of the piston ( 2 ). An extension side pilot chamber ( 6 ) urging a spool ( 8 ) in a valve-closing direction at pilot pressure introduced thereinto through a first orifice ( 32 ) in the extension stroke and a compression-side pilot chamber ( 7 ) urging the spool ( 8 ) in the valve-closing direction at pilot pressure introduced thereinto through a second orifice ( 43 ) in the compression stroke are formed at a back face of the spool ( 8 ) of the main valve. Also, the shock absorber comprises a pressure-receiving portion for receiving high pressure in the extension stroke and urging the spool ( 8 ) in a valve-opening direction against the pilot pressure and a pressure-receiving portion for receiving high pressure in the compression stroke and urging the spool ( 8 ) in the valve-opening direction against the pilot pressure. In addition, the shock absorber comprises an extension-side poppet valve ( 11 ) for regulating the pilot pressure in the extension stroke, a compression-side poppet valve ( 10 ) for regulating the pilot pressure in the compression stroke, and a solenoid ( 71 ) for urging to reduce initial loads of springs ( 9 ) of the extension-side and compression-side poppet valves ( 11 ) and ( 10 ) by passing current therethrough.
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