| 摘要 |
<p>971,821. Valves. HAMWORTHY ENGINEERING Ltd. Feb. 21, 1962 [March 28, 1961], No. 11252/61. Heading F2V. An hydraulic control valve comprises a body in which a control spool is slidably arranged for connecting a service port to a high pressure or a low pressure line, and a pressure compensated by-pass flow regulator carried by the spool for controlling the flow of fluid from the highpressure line to the service port, the regulator serving to maintain a pre-set flow to the service port by by-passing to the low-pressure line the unwanted part of the flow of fluid. As shown in a duplicated arrangement, an open-centre valve spool 2 is adapted to connect two service ports 9 and 10 selectively with corresponding pressure ports 8 and 7 or with a drain gallery 5 in body 1, through ports 17, 22 in the spool. In the neutral position shown, a main pressure supply to body 1 is connected direct to the drain gallery via annular recess 6 in the spool. Movement, e.g. to the right, connects pressure port 7 of the left hand regulator with service port 10 through spool ports 17, 22, this flow taking place past an annular clearance space 19 round the pressure balanced by-pass flow regulating valve 15 which is spring-urged on to a seat 11 connecting the ports 17 with drain ports 21 in the spool, the by-pass valve 15 on the left being responsive in this position to flow rate past the clearance space 19 to maintain the flow to the service port at a predetermined value and pass the unwanted flow to the drain gallery. In this operated position ports 22 of the other regulator 15 communicate with the gallery 5 and the total flow from the service port 9 is returned to drain.</p> |
