| 摘要 |
PURPOSE:In a piston-type hydraulic shock absorber having an oil sump for hydraulic oil, to improve comfortableness and safety of driving by mounting a relief valve facing the oil sump to change damping force characteristic depending upon an expanded and contracted position of a piston stroke. CONSTITUTION:A piston-type hydraulic shock absorber comprises a chamber A and a chamber B divided by a slidable piston 3. The chamber B leads to a tank 7 through an opening 5 and an oil pipe 6. Pressure P2 in an oil sump 10 of the tank 7 changes depending upon quantity of oil in it, that is, a stroke position of a piston rod 2, and a relief valve 24 receives the pressure P2 in the oil sump 10 which changes in proportion to a stroke position of the piston rod 2 so that its set pressure is changed. When the piston rod 2 is placed at a certain stroke position, the differential pressure between the pressure P2 of the oil sump 10 and that of a spring 28 acts upon a spool 13, wherein as the pressure P2 increases, the spool 13 is pushed toward an atmosphere chamber 20 more strongly to raise the pressure for opening the valve. Thus, damping force characteristic of position dependent type is obtained. |
