GB735952A - Mechanism for controlling fuel to a gas turbine engine - Google Patents

Abstract

735,952. Automatic speed control systems. BENDIX AVIATION CORPORATION. Feb. 25, 1953 [April 11, 1952], No. 5312/53. Class 38 (4). In Fig. 1, to maintain the speed of a gas turbine 10 at a desired value, a tachometer generator 34 produces an alternating voltage the frequency of which is proportional to speed. This alternating voltage is applied to thermionic valve circuits 36, 38 which respectively produce a corresponding direct voltage and add a component dependent on rate of change of speed. The resultant voltage is compared by a vibratory contact type comparator 28 with the direct voltage from a potentiometer 30 manually operated by a throttle lever 32. Any difference between the actual engine speed and speed selected by lever 32 thus results in a voltage from comparator 28 which is applied to an amplifier 26 controlling a reversible servomotor 24 adjusting a valve 64 to correct engine speed by controlling the supply from a fuel pump 14. During acceleration of the engine up to a speed selected by lever 32 the maximum fuel flow permitted is predetermined at each value of engine speed by a series of pre-set potentiometers 1<SP>11</SP>-50<SP>11</SP> which are selected by a servomotor 42 operating a. selector switch 246. Servomotor 42, which is controlled by an amplifier and which operates a follow-up potentiometer 44 and a rate feedback generator (not shown) takes up a position corresponding to engine speed as determined by the voltage output of circuit 36. The selected potentiometer then determines the position of a follow-up servomotor 52 adjusting a stop 84 limiting the maximum permissible opening of valve 64. Acceleration is thus controlled to avoid stall.