Patent GB-590493-A (GB)
Title: Improvements in or relating to carburetting apparatus for internal combustion engines
IPC: F02M69/00
Filed: 1944-11-21
Abstract: 590,493. Spray carburetters. BENDIX AVIATION CORPORATION. Nov. 21, 1944, No. 23154. Convention date, July 31, 1943. [Class 7 (iii) ] In a carburetter in which fuel under pressure is controlled by a valve responsive to fuel pressure and venturi suction the venturi being on the approach side of a throttle valve in the induction passage and the fuel passing to a discharge nozzle on the engine side of the throttle valve, the valve admits fuel to an emulsion chamber freely supplied with air at atmospheric or entering air pressure in which chamber an emulsion is formed and from which it is discharged into the induction passage through a restricted orifice in the discharge nozzle so dimensioned that the flow of air forming one component of the emulsion is unaffected by variation of suction in the induction passage above a critical valve of this suction. In a modification fuel under pressure is admitted by an inlet valve and passes through a restriction to an outlet valve responsive to metered fuel pressure and venturi suction the fuel then passing through a passage to a point where it is mixed with freely supplied air at atmospheric or entering air pressure the resulting mixture passing. to the induction passage through a fuel discharge nozzle having a restricted discharge orifice. As shown, Figs. 1 and 2, a discharge nozzle comprises members 164, 166 projecting from opposite sides of the induction passage. The member 166 has a reduced diameter portion 168 which telescopes within a hollow portion 172 of the member 164. Fuel enters at 184 and passes to an emulsion chamber 170 freely supplied with air at atmospheric pressure from the entrance of the carburetter through passages 28, 26, 200 and 188. Emulsion from the chamber passes into the induction passage through a restricted orifice 178 so dimensioned that above a predetermined value of the suction in the induction passage the quantity of air drawn through the passage 188 is unaffected by variations in the suction. Modified arrangements of the nozzle are shown in Figs. 4 and 6. In Fig. 4 fuel enters at 240 and air at 248 the resulting mixture passing to the induction passage at 252. In Fig. 6 the fuel enters at 264 air 268 and mixture leaves at 262. Other constructions of the nozzle are described. The control of the fuel supply is carried out by a regulating unit 32 a metering unit 34 and discharge nozzle valve 36. Fuel under pressure enters the regulator unit at 62 and passes through the valve 60 and chamber 40 to a pipe 98 leading to the metering unit. The valve 60 is controlled by diaphragms 48, 46, entering air pressure being supplied to a chamber 44 and venturi throat pressure to a chamber 42. The fuel passes through a valve 110 in the metering unit which is controlled by a diaphragm 106 operated on by venturi throat pressure at 108. When the engine is idling finger 156 on the throttle acting on a lug 132 holds the valve in position. When the throttle is opened beyond the idling position the diaphragm moves to the left and moves a shoulder on the valve away from the seat thus providing a fixed open position controlling cruising flow. A spigot on the valve is then adjacent the seat. When running at high power the suction is sufficient to compress a spring 146 and remove the spigot from the seat. From the metering unit the fuel passes to the fuel discharge control valve 154 by a pipe 102. The fuel discharge control valve is operated by venturi throat pressure on a diaphragm 152 and from the valve the fuel passes to the nozzle 166. A fuel well 212 receives, fuel at idling by suction through a pipe 206 on a diaphragm 208 and discharges the fuel during periods of acceleration. The altitude control capsule 96 which acts also as a thermostatic control by employing a highly expansible fluid in the bellows chamber 232 controls a leak between chambers 42 and 44 of the regulating unit. The altitude control may be mounted in the air inlet. The air passing to the nozzle may be heated by conducting a supply pipe around the engine exhaust conduit or by oil heating or electrically. A hand or thermostatic control valve may control the further admission of unheated air into the supply. Modifications of construction such as a regulator unit being combined with main body &c. are described. The carburetter is similar to the carburetters described in Specifications 590,528 and 591,471. Specification 577,770 also is referred to.