Patent GB-590528-A (GB)
Title: Fuel feeding systems for carburetters
IPC: F02M69/00
Filed: 1945-03-12
Abstract: 590,528. Spray carburetters. BENDIX AVIATION CORPORATION. March 12, 1945, No. 6198. Convention date, Dec. 27, 1943. [Class 7 (iii)] In a carburetter in which fuel is supplied under pressure through a fuel metering jet system to an engine induction passage the pressure of the fuel in front of the jet system being regulated by a valve controlled by the pressure of air at the entrance of a venturi in the induction passage, a pressure derived from the throat of the venturi and the pressure of the fuel itself while further an orifice with a manually controlled valve varies the effective difference between the venturi entrance air pressure and the pressure derived from the venturi throat air pressure thereby adjusting the opening of the fuel valve means are provided for closing the fuel valve by operating means for the manually controlled valve. As shown, fuel entering the carburetter is con trolled by a fuel regulating unit 32 which is divided into three chambers 40, 42, 44 by diaphragms 46, 48 spaced by a rod 55. Fuel under pressure enters the chamber 40 past a spring-pressed valve 60 which is normally held open by a spring 66 loading the diaphragm 48 but which, when the pressure of the spring is relieved is closed by the fuel pressure acting on the diaphragm 46. The chamber 42 is subjected to the pressure at the throat of a venturi 20 in the air inlet through passages 75, 76 a restriction 78, an annular chamber 22 and a slot 24 whilst the chamber 44 is subjected to the pressure at the air inlet through passages 85, 84 a restriction 86, annular passage 26 and an annular opening 28. In addition the chamber 42 is connected to the passage 84 through a passage 81 and a calibrated orifice 80 controlled by a manually operable valve 82 which allows air to be bled from the chamber 44 to the chamber 42 to control the fuel pressure in the chamber 40. From the chamber 40 the fuel is delivered through a metering unit, shown as a calibrated orifice 34 and a pipe 98 to a nozzle 159 on the engine side of the throttle 30 past a spring-pressed valve 154 which is opened by fuel pressure acting on one side of a diaphragm 152, the other side being subject to the pressure in the passage 76 and loaded by a spring 156. To cut off the fuel supply and stop the engine the valve 82 is moved beyond its full lean position whereby a collar 170 engages a lever 172 which moves a plunger 70 into engagement with the free end of a lever 68 to remove the pressure of the spring 66 from the diaphragm 48 whereupon a light spring 64 closes the valve 60. The plunger 70 can be operated independently of the valve 82 by closing a switch 192 which energizes a solenoid 180 to actuate the lever 172. In a modified construction the solenoid is controlled simultaneously with the ignition switch so that when the switch is opened the solenoid is' de-energized and a spring operates the lever 172. To correct the fuel flow for variations in density of the air entering the venturi the chamber 44 is connected to the passage 76 by passages 90, 92 communication between which is controlled by an altitude control formed by a valve 94, carried by a bellows 97, and controlling the differential pressure which exists in the chambers 42, 44. A supercharger may be connected to the inlet and/or outlet of the carburetter.