| 摘要 |
PCT No. PCT/GB96/03061 Sec. 371 Date Jun. 15, 1998 Sec. 102(e) Date Jun. 15, 1998 PCT Filed Dec. 12, 1996 PCT Pub. No. WO97/22809 PCT Pub. Date Jun. 26, 1997A hydraulic control valve (10; 110) which acts as a hydraulic flow amplifier. An obturator (34; 134) is slidable towards and away from a valve seat (36; 136) to controllably vary throughflow from an inlet (S; P) to an outlet (T; S). The obturator (34; 134) is mounted on a piston (30; 130) which is slidable in dependence on the excess of the difference between inlet and outlet pressures over control pressure in a control chamber (42; 142). The control chamber (42; 142) is fed with hydraulic fluid bled from the source (S; P) via a controlled leak (48+50; 148+150) which is self-regulating in dependence on throughflow-controlling movement of the piston/obturator (34/30; 134/130) in a sense which provides negative feedback. The control chamber (42; 142) is drained through a fluid conduit (54; 154) incorporating an externally-controllable fluid flow restriction (56; 156) which serves as the control input to the control valve (10; 110). The control valve (10) can be configured to control outflow from a load-connected service line (S) to a flow drain or reservoir (T), or, alternatively, the valve (110) can be configured to control inflow from a pressure source (P) to a load-connected service line (S). The invention may be used in both single acting and double acting applications. |
