Patent GB-347579-A (GB)
Title: Improvements in carburetters for internal combustion engines
IPC: F02M7/17
Filed: 1929-12-23
Abstract: 347,579. Spray carburetters. ROYCE, SIR F. H., Nightingale Road, Derby. Dec. 23, 1929, No. 39247. [Class 7 (iii).] The carburetter has a single " air-bleed " device which, without further adjustment, yields a correct mixture for the lower range of engine demand, automatic valves being provided to admit additional fuel to the air-bleed device and additional air to the mixing chamber when the depression on the carburetter side of the throttle valve exceeds a predetermined amount. A down-draught carburetter is described comprising castings a, b bolted together, the casting b, containing the throttle b<5>, being attached to the induction pipe b<4>. The bottom of the casting a is in the form of a diaphragm a<1> with apertures b<1>, b<2> to receive respectively a choke tube c and an extra-air valve i<4>. A casting d forced into a recess d<1> by a hollow screw d<2> has drilled passages d<3> .. d'. Within the hole d<7> are concentric tubes el, e2 forming the air-bleed device. The inner tube e2 may serve as an air supply, or as a drain to a tank or to waste for overflowing fuel. Above the bore d<7> is a tube e<3> the entrance of air to which may be adjusted by a screw e<4>. The fuel to form the mixture issues through a series of holes e<6>, the air entering by an elliptical opening f. The tube e<1> has a series of perforations e<7>. Spigoted into the top of the casting a and above it is a cylinder g containing a piston h connected by a pin i2 to a fuel needle valve i and the extra-air valve i<4>. The upper face of the piston is subjected to the suction in the choke tube c through passages g<5>, g<4>, g<3>. A dashpot action is produced by providing a series of holes i<5> which place the interior of the piston in communication with the space below the piston through the clearance between the piston and the cylinder wall. The aperture controlled by the needle valve i is formed in a sleeve k<5> having lateral ports, and adjustable axially in a fixed sleeve k<3> also having lateral ports k<4>. The sleeve k<5> is adjustable through a lever m, rod m<2>, nut m<3> and lever m<4>, the rod m<2> being prevented from rotating by projections m<6> thereon engaging grooves in the casting b. A fuel duct q leads to the space below a slow-running nozzle o<1>, the slowrunning mixture being conveyed through passage o<7> to a hollow plug p at the edge of the throttle valve. The plug p is adjustable and is bored eccentrically. Air is admitted to the idling carburetter through duct q3. Fuel from the float chamber passes the needle i and flows into duct d<6> and through duct q to the idling nozzle ; it will also pass into the bore d<7> and the space between tubes e<1>, e<2>. The air passes mainly through choke tube c, but a portion enters tube e<3> and on to the column of fuel, through holes e' and out as emulsion through holes e<6>. After a predetermined vacuum in choke tube has been reached, piston h opens needle valve i and the extra-air valve i<4>. Specifications 222,901 and 222,526, [both in Class 7 (iii), Internal-combustion engines, Carburetting apparatus &c. for], are referred to.