Patent GB-407233-A (GB)
Title: Improvements in carburettors for internal combustion engines
IPC: F02M31/093
Filed: 1933-07-06
Abstract: 407,233. Carburetters. POGUE, C. N., 166, Claremont Avenue, Norwood, Winnipeg, Canada. July 6, 1933, No. 19180. Convention date, Nov. 12, 1932. [Class 7 (iii).] In a carburetter, in which a supply of liquid fuel is maintained at the bottom of a vaporizing chamber and air is drawn through the fuel and along a passage to the intake manifold, a separate passage conducting air directly to tho manifold, a regulating valve, controlling the first but not the second passage, is automatically opened, during the operation of the engine, to an extent corresponding to the suction in the intake manifold and the vapour space in the vapour chamber is sufficiently large to ensure that only a minor portion of the vapour therein passes to the intake manifold. Sloping walls 71, 72 divide a vaporizing chamber 1 into upper and lower compartments communicating by an opening 73 and fuel, maintained at constant level in the lower compartment by a float 2, is heated by exhaust gases which pass through a surrounding casing 4 in a quantity determined by a thermostatically-operated valve 74. The exhaust gases also heat air which enters an outer casing 7 by an inlet 8 and passes partly through a pipe 9 to an aerator 10 disposed in the fuel supply and partly through a bye-pass 12 to an air passage 13 disposed above the vaporizing chamber. The passage 13 provides direct communication between the atmosphere and a pipe 15 leading to the induction manifold and engine suction draws in air past a valve 14 and a vapour and air mixture past a valve 17<a> normally closing an opening 17 between the passage 13 and the upper compartment of the vaporizing chamber 1, the mixture passing a Venturi constriction 20 into the pipe 15. Within the Venturi constriction 20 is a nozzle 21 extending downwards into a tubular member 22 which reaches to the bottom of the vaporizing chamber 1. A spraying nozzle 28 reaches from a plug closing the lower end of the member 22 to the lower end of the nozzle 21 and is supplied with fuel through apertures in the plug and member and through a passage controlled by a needle valve 33. At starting, a choke valve 13b in the inlet 13<a> to the passage 13 is closed to compel fuel to be drawn up the nozzle 28 and mix with air, drawn into the tube 22 through apertures 35<a> in the passage 13, both at the lower end of the nozzle 21 and at apertures made in the wall of the nozzle 28. Normal running is controlled by a mixture throttle valve 16 linked to valves 19, 18 in the passages 12, 9 respectively. An idling bye-pass 37 leads from the lower end of the member 22 to a point above the throttle valve 16 and is adjusted by a needle valve 42, air being admitted through the open upper end of the bye-pass and through an orifice 39 located in the part of the bye-pass disposed in the passage 13 and above a constriction 40. To ensure a plentiful supply of mixed fuel vapour and air, a two-cylinder pump 43, actuated by engine suction communicated to it by a pipe 51 through a distributing valve V, draws in air through adjustable orifices 59 and fuel from the fuel supply and pumps the mixture up a central pipe 68 to throw it against a deflecting plate 70 which permits any fuel droplets to fall back into the fuel supply. The degree of suction applied to the pump is controlled by a valve 52 linked to the throttle valve 16.