GB716415A - All-speed govenor for gas turbine engines - Google Patents

Abstract

716,415. Speed governors. BENDIX AVIATION CORPORATION. Dec. 1, 1952 [Dec. 26, 1951], No. 30445/52. Class 57 A speed governor system for an engine comprises a resettable governor 48 connected to a valve 44 which controls a fuel restriction 43 and is associated with springs 51, 52 adjustable to vary the setting of the governor, means being provided for effecting a balance between the springs during equilibrium operation of the system. This means consists of a dashpot piston 49 the position of which is controlled by a piston 53 and a lever 54 in accordance with the required setting of the governor. The restriction 43 is connected to an annular chamber 67 fed with fuel from a duct 42 in communication with a chamber 11 in which the pressure is controlled by a regulating valve 14 coupled to a spring-loaded diaphragm 13 and a second governor 33. When a variation in engine speed causes a movement of the valve 44 the resultant pressure fluctuation in the chamber 11 is compensated by the governor 33 displacing the regulating valve 14. The latter is supplied from a duct 18<SP>1</SP> containing a fuel pump 19, the pressure in this duct being controlled at a set value above the pressure in a duct 68 supplying the engine by a by-pass valve 21 and a spring-loaded diaphragm 26. A relief valve 32 is also provided. When it is required to increase engine speed, the dashpot 49 is moved to the right whereupon the valve 44 moves to its fully open position until the governor 48 has acquired sufficient speed to move it to its new equilibrium position. This closing action of the valve occurs too rapidly to permit the dashpot piston 49 to move and consequently is opposed only by the spring 51 which provides greater resistance to the movement of the valve than the combined effect of the springs 51, 52 so that the engine overshoots the new required speed until the dashpot has moved to its new equilibrium position with the springs 51, 52 in balance. To avoid this overshoot, the pressure on the left hand side of the dashpot piston may be reduced when the engine accelerates by a double headed piston 60 mounted in a chamber 62 connected by ducts 64, 65 with the dashpot and a chamber 41<SP>11</SP> containing an impeller 66. Acceleration of the latter by the engine displaces the piston 60 to the right to draw fluid through the duct 64 from the. dashpot. The system is particularly applicable to aircraft turbine engines and includes a supplementary fuel duct 71 controlled by an aneroid in spring-loaded bellows 75 to compensate for variation in the density of the air intake. Specifications 604,466, 612,840, 634,095 and 655,311 are referred to.