Patent GB-807519-A (GB)
Title: Improvements in a fuel feed system for internal-combustion engines
IPC: F02D9/00
Filed: 1955-11-07
Abstract: 807,519. Spray carburetters. ACF INDUSTRIES Inc. Nov. 7,1955 [June 20, 1955]. No. 31729/55. Class 7(3) In a fuel system comprising a pump P supplying fuel nozzles 25 through metering orifices 23, controlled by needles 33 according to engine operating conditions, the pressure drop across the orifices 23 is maintained independent of engine speed by a fuel pressure responsive device 28 downstream of the orifice and, for a given load on the engine, is substantially unaffected by variations in the pressure immediately upstream of the orifice. The pump P supplies, through a filter 21 and pressure-controlling valve 22b, a reservoir A containing the orifices 23, connected by pipes 24 to chambers 30 on one side of diaphragms 28 actuating the nozzle valves 29, and a control orifice 55 through which fuel passes into a control circuit 58 having branches leading to the other side of the diaphragms 28 and a return pipe leading to the supply side of pump P through a restriction 61 and an outlet 124 controlled by a diaphragm-operated valve 123 which ensures a minimum pressure in the control circuit The metering needles 33 are adjusted in accordance with air intake flow by a carriage 34 operated through a magneticclutch 35 by a connection to a balanced valve 37 in the air intake passage forming an air-flow measuring device and operated by a spring-loaded diaphragm 40 subjected to the pressures upstream and downstream of the valve 37. The needle 87 is adjusted through a magnetic clutch 86 by a device 70 which is responsive to load and which is combined with a bi-metallic coil 76 which produces a rich mixture at cold starting. The device 70 comprises a three-armed lever 69 connected to a spring-loaded piston 82 urged down its cylinder 83 by intake pipe suction from a point 116 below the throttle valve 50, a second arm 68 of the lever having an adjustable stop co-operating with the end of the coil 76. At cold starting the coil 76 overcomes the piston 82 and moves lever 69 to cause needle 87 to restrict orifice 55 which reduces the pressure in the control circuit 58 and causes increased opening of the fuel nozzle, valves. When the engine warms up the coil 76 moves towards a fixed stop 73 permitting the lever 69 to be moved by piston 82 to its normal position in which the end of the coil 76 is positioned between stops 72, 73. If the load increases suddenly, the drop in intake suction at 116 permits piston 82 to rise and lever 69 is rotated to move needle 87 in the increased fuel direction until a lug 99 on arm 68 abuts against the end of coil 76. The spring loaded diaphragms 28 maintain a constant pressure difference between the metered fuel circuits 24 and the control circuit 58 so that any fluctuations in the supply pressure of pump P do not affect the fuel supplied through the nozzles 25. A fast idle cam 64 is carried by the lever 69 and holds valve 50 open through a lever 66. To de-flood the engine, a switch 97 in a solenoid circuit 90 is closed when the throttle valve 50 is opened wide, permitting energization of solenoid 90 when the starter switch 93 is closed, whereby a valve 59 in the control circuit 58 is closed, causing closing of the fuel nozzles 25. Heated air from a heater 108, Fig. 5, in the exhaust pipe is drawn into the housing 102 of the coil 76 through a pipe 103, the housing 102 being connected through a restricted by-pass 101 to the suction side of piston 82. A by-pass 110 from the pipe 103 also leads heated air to a passage 113 adjacent the throttle valve 50, cold air from the supply pipe 111 of the heater 108 being bled into passage 113 when the engine warms up, to prevent overheating, through a by-pass 112 controlled by a valve 114 controlled by a second bi-metallic coil 105. The injection nozzles 25, Fig 20, are secured in mounting tubes 208 by screwthreaded nuts 210.