GB871378A - Fluid pressure device for controlling a process or an apparatus - Google Patents

Abstract

871,378. Fluid-pressure servomotor control systems; valves. LEUNA-WERKE WALTER ULBRICHT VEB. Oct. 29, 1957 [Aug. 8, 1957], No. 33715/57. Class 135. A fluid-pressure device for controlling a process or an apparatus comprises a nuid-pressure relay having a first pressure sensitive member or diaphragm 2 displaceable, on changes of the pressure acting thereon, to move a baffle 3 towards or away from an outlet nozzle 5 mounted on a tube 4a, said tube including a second pressure-sensitive member or integral bellows 4 which acts, on changes of pressure in the tube resulting from restriction of the nozzle by the baffle, to extend or contract the tube longitudinally and so cause the nozzle to move towards or away from the baffle, which changes of pressure in the tube serve also to actuate a regulator of the process or apparatus. In a system, Fig. 1, the changes of pressure in the tube 4 are used to actuate a diaphragm regulating valve 7 for filling or emptying liquid containers, the first pressure-sensitive member 2 being subject to a control pressure set up by changes of liquid level in a container 10. Constant air pressure is fed to restrictions 9 and 12 which are connected respectively to the tube 4a and the diaphragm 1, the restriction 12 also being connected to a bubble pipe 11 dipping into the container 10. On rising level in this container, the increased pressure on diaphragm 1 moves the baffle 3 towards the nozzle 5 and a correspondingly increased pressure in the tube 4a closes the regulating valve 7. Movement of the nozzle 5 is limited by stops 6, 6a and on falling level in the container 10 the nozzle follows the reverse movement of the baffle until limited by the stop 6. Fig. 2 shows a system in which a similar process regulating valve 7 is actuated in a timed cycle by an arrangement similar to that of Fig. 1, excepting that the container 10 is replaced by a closed pressure container 13, and the pressure-sensitive diaphragm chamber 1 is connected also through an additional restrictor 15 to a diaphragm-actuated leak-off valve 16 which is spring-closed and opened by pressure in a diaphragm chamber connected to the tube 4a. Timing of the operating cycle is determined by the relative sizes of the restrictions 14 (which corresponds to restrictor 12 of Fig. 1) and 15 in relation to the build-up of pressure in the container. Thus on a predetermined higher pressure being built up in the container the nozzle is closed by the baffle 3, thus actuating the regulating valve 7 and allowing the leak-off valve 16 to open. This leak-off valve exhausts the container 13 through orifice 15 quicker than the container can be supplied through orifice 14 so that on a predetermined low pressure in the container being reached after a given time interval, the nozzle is again opened, thus relieving the actuating pressure on the regulating valve and on the leak-off valve 16 which closes to recommence the cycle.