GB667816A - Improved carburetor for internal combustion engines - Google Patents

Abstract

667,816. Spray carburetters. GENERAL MOTORS CORPORATION. Feb. 1, 1950 [Feb. 18, 1949], No. 2579/50. Class 7(iii) A carburetter comprises a housing 12, Figs. 10, 11, with a horizontal air-inlet passage 50, having a choke valve 51, and a float chamber 14 mounted therein so that the air impinges thereon and is divided by a wedge 90 into two streams which pass respectively to two separate mixture outlets 201, Fig. 10, a further part of the air stream passing around the float chamber 14 and through passages 93 which are into primary Venturis 92 integral with the chamber 14, and coaxial with the outlets 201, and contain the fuel nozzles 100, Fig. 50. The choke valve 51 is held closed at cold starting by a thermostat and is urged open by a suction-actuated piston. The thermostat is anchored to plate 59, Fig. 4, which is rotatable for initial adjustment and is locked in position by member 63 engaging teeth 64 therein. A lug 217, Fig. 2, on the choke valve spindle co-operates with a lug 216 on a freely pivoted member 213 connected by a link 212 to a pivoted lever 210 carrying fast-idle cams 208. As the choke valve opens the member 213 rotates under gravity and moves the lever 210 so that the cams 208 permit the throttle valves 200 to move gradually from the fast-idle to the normal idling position. The choke may be forced open for de-flooding by a lug 220 contacting the lever 210 when the throttle valves are fully opened. The throttle valve lever 203 is also connected by a link 221 to a lever 222 which actuates a diaphragm type accelerating pump 235, Figs. 11, 50, feeding nozzles 257 which project jets of fuel against baffles 262, Fig. 50, on the entrances to the outlets 201 which improve the mixing of the air and accelerating fuel. The lever 222 is connected to a shaft 223, Fig. 11D, projecting through the casing 12 and carrying a lever 225, the arm 225a of which contacts a lug 226 on a spring-loaded lever 227 which rotates a pinion 231 to actuate the pump 235. On opening of the throttle valves 200, the lever 225 is moved anti-clockwise and the pump is actuated by the spring acting upon the lever 227. If the throttle valves are opened very suddenly the arm 225b contacts the lug 226 and actuates the pump directly. The cover 15 and float chamber 14 may be,removed without disconnecting any mechanism as the lug merely dis-engages from the lever 225. The fuel nozzles 100, Fig. 50, are fed from wells 104 connected to the float chamber by passages 122 and metering orifices 120. Both the passages 122 are also connected to a single power orifice 125 closed by a valve 130 which is opened at high power outputs by a member 152 actuated by a diaphragm 140 subject to intake manifold suction through a pipe 76. Each well 104 contains an air bleed tube 105 of kidneyshaped cross-section and the nozzles 100 contain a projection 102 which prevents dribbling of the fuel. Semi-circular projections 94 produce whirling of the fuel mixture at the outlets of the Venturis 92. Idling wells 162 are also fed from the passages 122. The float chamber 14 is bolted to the cover 15 of the housing 12 and is vented to the air inlet 50 through an arcuate channel 40, Fig. 11, and passages 43, 45. which may be provided witha cork ball 321, Fig. 53, which closes orifice 322 to prevent escape of fuel to the inlet 50 if the float valve 29, actuated by two floats 33, 35 connected by a yoke 34, becomes jammed open. The escape of fuel vapour to the inlet 50 through the passage 45 may be cut off at high temperatures by a double valve 318, Fig. 52, carried by a bimetallic strip 315 which closes an orifice 311 and opens orifice 313 to vent the float chamber to the atmosphere.