GB754854A - Improvements in jet propulsion engines including at least one control device for temporarily modifying the operation of said engine - Google Patents

Abstract

754.854. Gas turbine plant. SOC. D'EXPLOITATION DES MATERIALS HISPANO SUIZA. March 19, 1954 [March 20, 1953], No. 8129/54. Class 110(3) A jet propulsion engine having a control device operated by a servomotor using fuel supplied by the fuel feed pump as a power liuid has the power liquid taken from a by-pass between the discharge and suction sides of the feed pump through a reducing valve and an automatic valve device which is responsive to fuel admission to the servomotor to reduce or stop the flow of fuel through the by-pass. Fuel from a tank 1 is supplied by a pump 2 to main fuel injectors 3 and by a pump 4 to reheat fuel injectors 5. The pump 4 is controlled by an hydraulic servomotor 6 which is supplied with actuating fluid bled from a by-pass conduit 7 around the pump 2 to avoid any ill effects of the operation of the servomotor 6 on the fuel supply to the engine. The servo fluid is supplied through apparatus 8, Fig. 2, which comprises a spring-loaded slide valve 9 which maintains the pressure at its downstream side constant and a slide valve 16. The slide valve 16 controls the flow through the conduit 7a to the suction of the pump and the supply 18 to the servomotor 6. When the servomotor 6 is not in operation, the slide valve occupies the extreme righthand position and fuel flows through the by-pass circuit which includes conduit 7, chamber 11. orifice 13, chamber 15 and conduit 7a. When the servomotor is operated liquid is drawn from the chamber 15 and the orifice 13 causes a pressure drop in the chamber and slide valve 16 moves to the left and gradually closes the inlet ports to the conduit 7a and thus reduces the flow through the by-pass. After operation of the servomotor 6, the pressure in chamber 15 builds up and spring 17 pushes the slide valve 16 to the right and restores the flow through the by-pass. The valve 16 may be provided with slots 16a to prevent the action of the valve being too abrupt. The loading of the springs 10, 17 may be adjustable. To avoid a delay in starting due to the presence of the by-pass circuit, a valve 19, which is opened only when the speed of the engine reaches a predetermined value, may be provided.