GB760095A - Improvements relating to relay valves - Google Patents

Abstract

760,095. Fluid-pressure servomotor-control systems. BRISTOL CO. Nov. 1, 1954, No. 31518/54. Class 135. A valve for controlling the flow of fluid from a source 12 to a conduit 14 leading to a fluidoperated motor 16 in response to variations by independent control means 47 of the flow of a relatively small volume of the fluid from the source to the atmosphere at orifice 42, comprises a body 20 having a bore with, e.g., spaced ports 25, 27 communicating with the conduit and the atmosphere respectively, movable means, e.g. a piston 21 in the bore with one end exposed to the pressure from the source and the other end defining a variable volume space between the piston and the orifice and allowing communication between the source and the conduit when the piston is in one position and between the conduit and atmosphere in another position, and elongated capillary tube means 40 providing restricted communication between the space and the source. A spring 41, co-operating with pressure in the space, tends to move the piston towards the position in which the conduit 14 is connected to atmosphere. The diaphragmoperated valve 16 may be controlled by a process cycle controller or a thermostat actuating a hinged valve 47, a rotary edge cam or a rotary disc valve controlling the nozzle.