GB734580A - Liquid fuel control means for jet-propelled aerial bodies - Google Patents

Abstract

734,580. Jet propulsion plant. LUCAS (INDUSTRIES), Ltd., J. April 17, 1953. [Jan. 23, 1952], No. 1853/52. Class 110 (3) [Also in Group XXIX] The regulating means of the liquid fuel supply to the combustion chamber of a ram jet engine is combined with an automatic selector device whereby the regulating means is initially responsive to the ram air pressure and subsequently to the combustion chamber pressure, the selector device being responsive to a pressure condition associated with the combustion chamber, ram air or the ambient atmosphere. Fuel from a pump b passes through a conduit c, throttle valves a, u and conduit d to the burners e of a ram jet. The throttle valve a is formed on one end of a servo-motor piston h the position of which is determined by a vent valve m which is opened or closed by a pressure-responsive capsule t. The position of the throttle valve u is determined by a vent valve 3 controlled by a flexible disphragm 7 loaded by the fuel pressure at the discharge of the pump band a spring 6. The rate of fuel flow is thus controlled by the fuel pressure in the pipe c and by the pressure in the chamber r. The chamber r is connected through a selector device 9 with a pipe 12 leading to the inlet of the ram jet and a pipe 15 to the combutsion chamber of the engine. When the pressure in the combustion chamber is increasing the diaphragm 20 moves upwards and operates a bell crank 19 which disengages the stop 16 from the stem 18 of the valve 13. The valve 13 then moves upwards under the action of the spring 25 until it abuts against the arm 19 of the bell crank. This movement is insufficient to move the piston 13 out of the cylinder 10. When a steady pressure in the combustion chamber is reached the pressures on each side of the diaphragm 20 are equalized and the bell crank is returned to the position shown. The stop 16 is prevented from returning to its original position by the stem 18 of the valve 13 so that the piston 13 rises further. In this position owing to the restricted orifice 27, the pressure in the chamber r is mainly responsive to the pressure in the combustion chamber. A modified form of selector device is shown in Fig. 2 where a chamber 14 contains an evacuated capsule 30 attached to one end of a lever 31, the other end of which is attached to a flexible diaphragm 20. The sub-chamber 22 is open to atmosphere. A stop 16 which acts on the stem 18 of a spring loaded valve 13 is carried by the lever 31. Initially the pressure in the pipe 11 leading to the fuel-regulating means is responsive to the inlet air pressure to the ram jet. When this pressure exceeds a predetermined amount, determined by the prevailing atmospheric pressure, the stop 16 is moved away and the spring 25 moves the valve 13 on to a seating which isolates the pipe 11 from the pipe 12 and connects it to the pipe 15. In another modification, the selector device is arranged to change over the control when the ratio of the inlet air pressure to the combustion chamber pressure attains a predetermined figure. In a further modification, the selector device, when the inlet air pressure exceeds a predetermined amount determined by the prevailing atmospheric pressure, changes the controlling pressure from the inlet of the engine to the combustion chamber and on a further rise in the inlet pressure the controlling pressure is made the atmospheric pressure.