GB1375671A - - Google Patents

Abstract

1375671 Fluid logic and switching circuits JOHNSON SERVICE CO 25 Jan 1972 [25 Jan 1971] 3545/72 Heading F1D A fluid logic circuit comprises a fluid signal sensing device 4, 7 Fig. 1 having a high impedance output line 9 leading to the input chamber 12 of a fluidic repeater 3 having a gain of one and having an output chamber 13 connected by a line 18 to variable stream orifice 20 of a fluidic modulator 2 having one or more constant stream orifices e.g., orifice 21. The sensing device is of the bleed type wherein a nozzle 4 supplied from a constant source of compressed air 5 through a restrictor 6 is obturated by a mechanically or electrically actuated member 7 so as to be positioned relative to the nozzle 4 in accordance with the sensed condition. The repeater 3 has a diaphragm 11 and an exhaust nozzle 15 which, when chamber 12 is momentarily pressurized, becomes obturated by the diaphragm thus generating a pressure pulse in chamber 13 and line 18 which latter is connected to a supply line 16, as well as to nozzle 20. Modulator 2 is of the summing impact type and has a control orifice, (not shown), and a collector 24 the output of which is controlled by the relative position of the point of impact between streams from nozzles 20, 21 and of the position of the control orifice. In a modification fluid resistances 36, 38 Fig. 3 which may vary with temperature are connected by a line 40 to the input chamber 43 of a repeater 41 having a diaphragm 42 and an intermediate fixed wall 49 with an aperture 50 adjacent the exhaust nozzle 48 thus forming a control chamber 44 and an exhaust chamber with exhaust port 51. The modulator 41a is of the transverse impacting type wherein the pulsed output of repeater 41 is fed to a nozzle 52 which thus deflects a constant stream from a nozzle 53 disposed opposite a second constant stream nozzle 54 to provide an output from collector 55 which varies with changes in values of resistances 36, 38 or changes in values of signal sources 37, 38 of said resistances. In a modification, temperature responsive resistances 57, 58 Fig. 4 form two legs of a bridge network having third and fourth legs formed by sensing resistances 60, 62 respectively. A summing output modulator 64 is connected in the circuit together with repeaters 66, 71. The output signal Po of the modulator is controlled by the relative strength of the input signals to nozzles 65, 69. Several further circuits are described each having a repeater positioned between a signal to be sensed and a modulator.