GB866721A - Improvements in or relating to fuel systems for gas turbine engines - Google Patents

Abstract

866,721. Centrifugal governors. BRISTOL SIDDELEY ENGINES Ltd. Aug. 27, 1959 [Aug. 28, 1958; May 26, 1959], No. 27585/58. Class 57. A centrifugal governor 9 for controlling the fuel supply valve 1 of a gas turbine is loaded by a variable spring means 14, 15 arranged to act on the valve in opposition to the governor, the effective rate of the spring means being automatically adjustable in response to the engine throttle setting in order to maintain the sensitivity of the governor substantially constant, or otherwise controlled, throughout its operating range. As shown in Fig. 1, the governor 9 acts through a pin 8 against a lever 7 connected to a pivoted lever 4 on which the valve 1 is mounted, the governor being loaded by two springs 14, 15 acting against the lever 7 through a pivoted arm 10. The springs are connected by levers 16, 17 to cam plates 20, 21 keyed to a common shaft 22 (Fig. 1 shows the cam plates spaced apart for clarity) connected through a linkage 23 to the throttle control lever. When the throttle control is moved between maximum and minimum settings defined by stops 24, 25, the cams are rotated and so move the springs around the curved arm 10, the desired loading on the springs being determined by the shape of the cams. A locking device 29, 30, 31, 33, responsive to change of atmospheric pressure, is provided for overriding the throttle control means to prevent the reduction of engine speed selected by the throttle control means falling below a minimum value required to maintain adequate combustion under the conditions of altitude and forward speed to which the device is responsive; the locking device is coupled to the shaft 22 by a lever 28 and prevents the valve from being closed beyond a certain minimum value irrespective, of the action of the governor, and a slip-coupling device 26 is provided in the throttle control 23. In the modification shown in Fig. 2, a single spring 49 is moved around a curved lever 48 by a linkage 54, 55 which replaces the cams 20, 21 and is coupled to the throttle linkage 51, 52, 53; a stationary spring 56 acts continuously on the lever 48 in order to ensure that the desired sensitivity is obtained in the idling position. A locking device 60, 61, 69, responsive to changes of atmospheric pressure, acts through a rod 70 on the arm.43 to hold the valve half open. A weak spring may be provided between the throttle linkage and the housing to take up backlash. Specification. 866,722 is referred to.