GB577770A - Improvements in carburetters for internal combustion engines - Google Patents

Abstract

577,770. Spray carburetters. CLEVELAND, F. J. (Bendix Aviation Corporation). Nov. 16, 1944, No. 22756. [Class 7 (iii)]. In a carburetter of the type having an inlet valve and an outlet valve and between these valves a metering device or orifice, fuel being supplied under pressure, the inlet valve is controlled by the pressure of the air supply, the air pressure at a venturi throat and the fuel pressure obtaining before entry into the metering device or orifice. As shown in Fig. 1, entering air pressure is supplied by a passage 48 to chambers 27, 29 and venturi throat pressure to a chamber 28 so that the diaphrams 31, 32 control the inlet valve 41. In a modification, the chamber 27 is dispensed with by removing the partition 33. Fuel from the inlet valve passes through the metering orifice 25 or a suction operated bypass 85 at high power to the outlet valve 94 of a discharge nozzle 23 controlling the fuel flow into a nozzle 97 in the induction passage. The metering orifice may be replaced by a valve held in during idling by a connection with the throttle valve released for cruising and withdrawn from its seat by suction and fuel pressure for high power operation (Fig. 2, not shown). The pipe 50 which connects the chamber 28 to the venturi throat 18 may as shown be led to a passage 51 between two rectrictions 53, 54 the other side of the restriction 53 being in communication with the throat 18 and the other side of the restriction 54 being in communication with one side of a diaphragm 92 controlling the outlet valve 94. From the outlet valve side of the restriction 54 a leak hole 55 passes to a passage 56 which has further leak holes 57, 58 leading into the induction passage. During idling the high suction on the engine side of the butterfly valve 21 passes through the holes 58 and 55 to the diaphragm 93 and to the chamber 28 thus opening the inlet and outlet valves and enriching the mixture. The leak hole 58 can be adjusted by means of a screw as shown. A control valve 61 can be opened to create an adjustable leak between the chambers 27 and 28 thus varying the richness of the mixture supplied by the carburetter. An altitude and thermostatic capsule 69 similarly arranged to create a leak between the chambers may control the mixture in accordance with the temperature and pressure of the incoming air. The nozzle receives air by a passage 100 connected to the venturi entrance and this mixes with the fuel before discharge into the induction passage. A modified outlet nozzle, Fig. 5, may be used having air supplied at 283 and fuel at 279, mixing being prevented until entrance into the induction passage by a member 278. In Fig. 6, the chambers 329 and 327 corresponding to the chambers 29 and 27 of Fig. 1, are connected to the air surrounding the carburetter. The arrangement of the chambers with respect to the induction passage is varied. The outlet valve 394 opens directly into the induction passage. Leak holes 401 and 402 are provided for enriching the mixture at idling and a piston 408 modifies the effect of the leak hole 402 relieving the suction on the engine side of the throttle valve. Various other ways of arranging the parts of the carburetter are described such as mounting the altitude capsule in or adjacent the air inlet &c. and different positions for the various orifices &c. are referred to. The diaphragms may be of different sizes. Two or more adjacent venturis may be used A device for supplying extra fuel for acceleration may be connected to a chamber 92 of the fuel discharge nozzle 23 the device sucking in fuel during idling and discharging it when suction in the induction passage is destroyed by opening the throttle. A plunger 46 is provided to cut off the fuel when the engine is stationary by compressing the spring 44 and allowing a spring 43 to close the inlet valve. The carburetter is similar to that described in Specification 590,493.