GB1197897A - Improvements in or relating to Fluid Control Valves - Google Patents

Abstract

1,197,897. Electromagnetic actuators. NORRIS SYSTEMS Ltd. 25 Aug., 1967 [26 Aug., 1966], No.38287/66. Heading H1P. [Also in Divisions F2 and G3] Valve for accurate and rapid control of fluid at high pressures, e.g. 15,000 p.s.i., comprises a needle member 5 having separate tapered portions which co-operate with two spaced orifices 9 to control flow from an inlet chamber 8 between the orifices, to a common outlet 18. The valve is operated by a moving coil, positioned in an annular magnetic field concentric with the needle axis. As shown, the needle is fixed between stationary permanent magnets 13, and the orifices are formed in a movable bobbin which carries coils 12 at opposite ends. A signal representing the valve position is obtained from a pick-up coil 16 co-operating with a mumetal wall of the bobbin. In an alternative arrangement, Fig. 2 (not shown), the orifices are formed in a stationary housing whilst a movable needle carries the coils (12). The inductive pick-up may be replaced by a resistive, capacitive, or photo-electric sensor. The permanent magnets may be replaced by electromagnets, and for cryogenic applications a coil only, of superconductive material may be used without any magnetic structure. In a control arrangement, Fig. 3 (not shown), an electrical feedback transduced from the pressure or flow output is compared with a demand signal representing flow or pressure and fed with this signal through a combining network of which the output is further combined with a feedback from the position pickup, and error rate and integral signals are applied. In a modified arrangement, Fig. 4 (not shown), a bias increasing with valve displacement is applied by connecting one coil 12a) with the pick-up (16) through a control circuit 25. The needle and orifices may be of hardened steel, tungsten, carbide, ceramic ruby or sapphire.