GB412958A - Carburettors for internal combustion engines - Google Patents

Abstract

412,958. Spray carburetters. CARTER CARBURETOR CORPORATION, 2838, North Spring Avenue, St. Louis, Missouri, U.S.A. Nov. 5, 1932, No. 31301. Convention date, Nov. 7, 1931. Addition to 412,957. [Class 7 (iii).] The parent Specification relates to a carburetter having an air inlet valve which is opened by a suction or pressure operated mechanism as the engine warms up, to an extent determined by a thermally-responsive device. According to the invention, the valve is formed of two parts, one of which is connected to the suction or pressure operated means and is prevented from opening during cranking of the engine, whilst the other part is permitted to open to a limited extent during cranking and to open fully under the action of suction when the engine is running under its own power. In the down-draught carburetter shown, the air-inlet valve 43, Fig. 10, comprises a part 45 fixed to its shaft, and a hinged portion 47 which may be opened by suction against the action of a spring 48. When the valve is closed, a latch 49 carried by the part 45 contacts with a shoulder 50 in the air inlet, and positions a finger 49a in the path of a lug 51 carried by the part 47, to limit its opening movement during cranking. As the valve 43 opens, the latch 49 reaches a position in which the finger 49<a> does not interfere with the lug 51, and then the part 47 can be fully opened by suction. As soon as the engine commences to run under its own power, the lubricating-oil pump supplies oil past a spring-pressed check valve 71, Fig. 6, into a cylinder 64 to raise a piston 75, which, through a rod 80 and a cam-plate 61, Fig. 2, gradually opens the air-inlet valve to an extent determined by a heat-responsive device 52, which actuates a cam shaft 57 having cam surfaces 58, 59 which, by engagement with stops 62, 63 on the cam-plate 61, limit the movement of the valve. As the engine warms up, the heat-responsive device 52 raises the cam shaft 57 to allow the piston 75 to open the valve fully. When the engine is stopped, the check valve 71 allows the oil to flow out of the cylinder 64, and a spring 76 forces the piston 75 downwardly until the stop 62 contacts with the cam surface 58, partly closing the valve 43. As the engine cools, the heat-responsive device draws the cam surface 58 downwards to permit the valve 43 to close fully. Liquid fuel is supplied to the float chamber by a pump, and passes through a metering orifice, controlled by a needle valve operated by the throttle valve 24, to a common passage from which fuel is discharged at idling through a passage 40 to a nozzle 41 at the edge of the throttle valve, and, during normal running, through a nozzle 42 in the smallest of a series of Venturi passages 35. A pump operated by the throttle supplies additional fuel during acceleration through a separate nozzle.