GB705702A - Improvements in or relating to gaseous fluid relays - Google Patents

Abstract

705,702. Fluid-pressure servomotor control systems. REGULATEURS FRANCEL. July 20, 1951 [July 21, 1950], No. 17260/51. Class 135 In a gas-actuated servomotor in which the variations of a variable are applied to a baffle interposed in the path of a jet issuing from a nozzle so as to produce corresponding pressure variations in the fluid upstream of the nozzle, the latter is shaped so that the jet is contracted downstream of the outlet from the nozzle and the baffle is located at A ... A, Fig. 4, in this contraction. In an embodiment, the baffle is constituted by a disc or crown cam 46, Fig. 8, carried by a galvanometer 48, and the pressure variations produced in the system downstream of a throttle 55 are applied to a capsule 51 acting on a lever 43 which carries the nozzle 42. After a movement of the cam, the nozzle will thus be reset into a neutral position with respect to the cam. The output of the system is constituted by the movements of lever 43. The cam 46 may be rotated by alterations in the length of a hair when the latter is subject to changes in humidity. When the variable is a temperature, a fluid subject to the latter is contained in a Bourdon tube the distortions of which are communicated to a baffle carried on a lever pivoted at one end. In a system comprising relays, the pressure variations produced upstream of the nozzle 99, Fig. 12, are applied to a diaphragm valve 102 controlling a vent from a bellows 105 supplied with fluid under pressure past a restriction 114a. The movements of bellows 105 actuate a lever 106 carrying a pointer 107 and a recording pen 110, and they are also applied through a link 117 and lever 119 to reset nozzle 99 to the neutral position relative to a cam 98 which is moved by a galvanometer subject to the variable. Lever 106 carries a baffle 131 co-operating with a nozzle 130 to produce pressure variations in a bellows 144 corresponding to variations in the variable, and the movements of the bellows are applied to a lever system 124, 128 to reset nozzle 130 and baffle 131 to neutral position. A screw adjusting means 125 permits of the position of nozzle 130 being pre-set with respect to baffle 131. Lever 124 carries also an inclined abutment 135 which acts on a baffle 137 carried on a spring arm, and subject to the jet issuing from a nozzle 136, and movements of this baffle cause corresponding variations in a pressure fluid supply to a diaphragm motor 150 controlling a valve 148. Nozzle 136 is carried by a bellows 140 also subject to the pressure variations produced by movements of baffle 137.