GB825548A - Improvements relating to valves for controlling gas flows - Google Patents

Abstract

825,548. Electrically-actuated valves. METROPOLITAN-VICKERS ELECTRICAL CO. Ltd., and NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 13, 1956 [April 15, 1955], No. 10966/56. Class 135. A valve for controlling gas flows comprises an annular seating member 4 surrounding a gas orifice and a closure member 7 movable a short distance away from the seating member to open the valve, one of the members being of semiconductor material and the other of metal, or both the members being of semi-conductor material so that when a predetermined electrical potential difference is applied between the members their abutting surfaces which are optically ground together are maintained in engagement to close the valve. Preferably the seating member 4 is of metal and the closure member 7 is of semi-conductor material such as an oxide of chromium, cobalt, iron, nickel, or titanium or material containing such oxides. Fig. 1 shows a flap valve 7 mounted on a leafspring 8 having a fixed support 9. The seating 4 is held against a rubber washer 6 adjacent the outlet 3 of a gas reservoir 1 by a clamping-ring 5. The spring 8 is chosen so that the period of vibration of the member is similar to or longer than the period required to empty the reservoir, the latter being supplied at a constant rate. The rate of flow through the orifice 3 may be altered by alteration of the potential difference across terminals 10. Thereby the frequency of oscillation is changed. By further increase of the potential difference, the valve is held closed against the gas supply pressure. The vibration may be effected electromagnetically, or pneumatically in the manner of an organ pipe reed by intermittent pressure set up in the reservoir. More than one leaf-spring may be employed. The leaf-spring may be replaced by a helical or other spring. The clamping ring may be dispensed with. In a modification the closure member 7 is mounted in a rubber cup supported by a series of springs each anchored to an adjustable screwed rod. In the case of small gas flows the closure member may be moved directly by the attractive force between the semi-conductor and the metal.