| 摘要 |
PURPOSE:To make flow control from neutral attainable without installing any other solenoid valve, by constituting a pilot part with two poppet valves, while making a fluid so as to flow into space between a pressure oil source and a pressure receiving chamber when a pilot valve operates its throttle motion. CONSTITUTION:A pilot part Z is constituted of each of poppet-type symmetrical pilot valves 25 and 26 being driven by symmetrical solenoids 27 and 28. And, thses symmetrical pilot valves 25 and 26 are put into possession of such a function as making a fluid flow into space between a pressure oil source and symmetrical pressure receiving chambers 17 and 18 when these valves 25 and 26 operate their throttle motion. With this constitution, even if dust is mixed in, no malfunction happens there, thus smooth flow control is performable. In addition, a difference is produced in pilot pressure inside each of these symmetrical pressure receiving chambers 17 and 18 and thereby a flow control spool 10 can be moved in both directions from neutral so that the flow control from the neutral is performable without installing any other pressure oil source or solenoid valve. |
