GB388783A - Improvements in spray carbureters for internal combustion engines - Google Patents

Abstract

388,783. Spray carburetters. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Ensign Carburetor Co., Ltd. ; Huntington Park, California, U.S.A.) Sept. 1, 1931, No. 24519. [Class 7 (iii).] A suction-actuated throttling member 50 which is controlled by a dashpot 53 open at one end to the float chamber 10 is located adjacent a fuel outlet in the wall of the carburetter and slightly above a Venturi passage having orifices through which sufficient suction is transmitted to the fuel to raise it from the float chamber 10 to the level of a chamber 22, from which it is conveyed to the delivery point by the suction prevailing at the fuel nozzle 35. In the construction shown in Fig. 1, fuel is drawn from the float chamber past a manuallyoperated valve 16 into a tube 15 in which it is raised to the level of the chamber 22 and from this position the fuel is conveyed to the nozzle 35 through passage 36, 37. Prior to issuing from the nozzle the fuel is mixed with air which enters through orifices 24 and serves to collect fuel which may accumulate in a trough 19a. Surrounding the tube 15 is a well 18 from which extra fuel is drawn through an orifice 21 during periods of acceleration. Fuel enters the well through an orifice 18b and the top of the well communicates with the float chamber through an orifice 18a and with the interior of the tube through an orifice 15a. To provide a rich mixture a valve 65 is provided to throttle that part of the chamber 22 adjacent the fuel passages. During slow running, a suctionactuated valve 40, shown vertically in Fig. 1, but actually disposed horizontally as shown in Fig. 6, is moved to restrict the passage 36 leading to the fuel nozzle ; the fuel-air nozzle then passes around the periphery of the valve to a passage 44 which discharges above the throttle valve 28. To reduce the strength of the mixture by increasing the suction above the fuel in the float chamber when the throttle valve opens, a passage 60 is provided which communicates with the float chamber, and also through a duct 61 with a controlled orifice 62 located on the carburetter side of the throttle valve. Thus as the throttle is opened the suction at the orifice 62 is increased. To ensure that the carburetter shall give a relatively richer mixture when the throttle is opened quickly at low speeds than at high speeds, the Venturi passage is shaped, as shown in Fig. 1, its curvature increasing at an increasing rate in the direction of air flow. Also, a sluggish action of the throttling member 50 ensures that during periods of acceleration the fuel supply shall increase before the member 50 assumes its new position of equilibrium. Eddy currents above the Venturi passage sweep over the head of the throttling member to atomize drops of fuel deposited thereon. Detail modifications of the slow running devices are described in which (1) the valve 40 is dispensed with, and the rich mixture which enters the chamber 36, Fig. 1, is diluted with air from above the fuel in the float chamber, and finally conveyed to the conduit 44 which discharges above the throttle valve, (2) air from the space above the fuel in the float chamber is conveved to the conduit 44 into which fuel is discharged through a pipe which dips into the float chamber, and (3) a valve 40g, Fig. 10, which controls the passage 36 leading to the nozzle 35, Fig. 1, is actuated by a cam 74 carried by the spindle of the throttle valve 28. The cam is so shaped that the passage 36 is fully open when the engine is running at half speed.