| 摘要 |
<P>PROBLEM TO BE SOLVED: To eliminate response delay as a switching vale is opened to start a machine while relaxing a shock at the stop of the machine as a J/S (hydraulic joystick valve) is returned to the neutral and having proper stopping characteristics. <P>SOLUTION: In a hydraulic circuit having a pilot operated switching valve 3 in an oil path from a hydraulic pump 8 to an actuator, on-off valves 6, 7 each having a check valve with an orifice and a spring in parallel with a pilot line in the opened state and the closed state are provided, in the pilot lines on both sides of the pilot operated switching valve 3. When pilot pressure rises, pilot pressure acting in the one on-off valve 6 is acted in a direction to open the other on-off valve 7, putting the other on-off valve 7 in the valve-opened state, and meanwhile, when the pilot pressure lowers, return oil of the pilot operated switching valve 3 is passed through the orifice of the check valve with the orifice of the one on-off valve 6 while the one on-off valve 6 is brought into the vale-closed state when the pilot pressure is higher than setting pressure of the one on-off valve 6, or is passed though the one on-off valve 6 while the pilot pressure is lower than the setting pressure with the one on-off valve 6 in the valve opened state. <P>COPYRIGHT: (C)2012,JPO&INPIT |
