GB1331867A - Carburetters for internal combustion engines - Google Patents

Abstract

1331867 Spray carburetters SOC INDUSTRIELLE DE BREYETS ET D'ETUDES 19 Jan 1971 [2 Feb 1970] 2471/71 Heading F1B I. C. engine carburetter comprises an auxiliary starting and cold operating device consisting of a distributor which opens a passage for fuel leading to the zone of the intake pipe downstream of the throttle; an enriching device consisting of a chamber divided by an element sensitive to the suction in the above zone and adapted to open or close as the suction is less or greater than a predetermined value, and a second fuel passage leading to a restricted cross-section portion of the intake pipe upstream of the throttle; and functions so that when the distributor is operating it weakens the suction acting on the sensitive element relative to the suction in the said zone. Fuel from a float chamber 1 passes through a main jet 6 and a passage 5 to nozzles 9 situated in venturi 10 in the main air intake pipe 8. Air enters a jet 7 to mix with the fuel. The distributor consists of a plate 13 having a large hole 27, a smaller hole 26 and an arcuate slot 43 which can be brought into alignment with holes 22, 20 and 42 respectively. When throttle valve 12 is closed and the engine is started, the suction on the downstream side of it is transmitted to chamber 18 and draws fuel through a jet 21, a passage 14 and the hole 26. This fuel mixes with air drawn through a duct 24 and jet 25 and enters the engine through passage 14b. The enriching device consists of a diaphragm 30 which partitions a chamber into a part 31 which is connected by a passageway 32 and a jet 33, to the passage 14b: and a part 36 from which a duct 39 leads to a nozzle 40 situated in the venturi. A spring 38 biases the diaphragm to a position in which a valve member 34 is held off its seat 35. The spring force is opposed by any depression existing in the space 31, and any such depression is modified by existence of the passage 41 which leads from the chamber 18 to the passage 32 and joins it on the diaphragm side of the jet 33. The sizes of the jets 25-33 are such that when the throttle is closed the depression acting on diaphragm 30 is insufficient to overcome the spring 38 and valve 34 remains open so that additional fuel is supplied through nozzle 40 to provide a rich mixture for starting. This condition prevails as long as the distributor plate 13 is in an angular position such that the slot 43 and hole 41 are aligned, and the throttle is closed or slightly open, so that a rich mixture is supplied at small throttle openings while the engine is cold in order to minimize pollutants in the exhaust gases. When the hole 41 is closed the suction acting on the diaphragm is sufficient to close valve 34, except at large throttle openings, when the enriching device again comes into operation.