GB362924A - Improvements in or relating to carburetting apparatus, particularly for internal combustion engines of motor vehicles, air craft, and the like - Google Patents

Abstract

362,924. Spray carburetters. HALSEY, W., 4, Densome Wood, Wood Green, Salisbury, Wiltshire. Aug. 11, 1930, Nos. 24011/30 and 11311/31. Class 7 (iii).] The fuel flow is controlled by a valve actuated by a diaphragm, or the equivalent, subjected to the vacuum on the engine side of the throttle valve as modified by an inflow of air from a source at which the density is substantially the same as that of the main supply to the carburetter, the control being such that a constant fuel to air ratio is maintained under all phases of speed and air density, but the flow is restricted if the engine speed becomes high relatively to the throttle opening. A casing 10 is divided by a flexible corrugated diaphragm 11 into two compartments 12, 16, of which 16 is in communication through ducts 28, 29, Fig. 2, with the engine side of the carburetter throttle valve, and 12 is in communication through ducts 13, 13a with an annular chamber 14 supplied with fuel from an overhead tank through a filter 15. The diaphragm carries at its centre a screw 17 which is adapted to actuate in one direction, a fuel valve 20 with two seatings 22, 23, and, in the other direction, a supplementary air valve 21. When the engine is at rest, the valve is closed against the seat 22 and the fuel is cut off. During running, the valve is held in a position between the seats, but should the vacuum become excessive, it is drawn downwardly towards the seat 23 and the flow of fuel is reduced ; at the same time the valve 21 is opened and air admitted to the chamber 16 and thence to the induction pipe. To regulate the rate at which the chamber 16 is exhausted, a needle valve 25 is provided which controls an orifice 27 between the ducts 28, 29, the valve being loaded by a spring 36 and sliding in a bush 32, its outer end 31 being actuated by a setscrew 39 mounted in a lever 38 connected to the throttle-actuating mechanism. Initial adjustment is effected by rotating the bush 32. Any sudden opening of the throttle valve releases the diaphragm abruptly and fuel is forced to the float chamber to facilitate acceleration. A decrease of air density will result in a lowering of the diaphragm and reduction of fuel supply. A valve 40 loaded by a spring 41 is adapted to control a further supplementary air supply and is connected, through a lever 42, with adjustable fulcrum, to the valve 21. Fuel may be bye-passed direct to the float chamber through a duct 48. In a modification, a simpler form is described in which the fuel valve is located in the fuel-pipe line. In a further modification, the diaphragm is embodied in the carburetter float chamber, and a piston on the fuel valve stem acts as a pump to facilitate acceleration. Water vapour may be admitted through the supplementary air valve, a porcelain diffuser 67, Fig. 9, receiving water from the radiator through a perforated tube 68, air entering through holes 69 and passing to the air valve by a pipe 70 of small bore.