GB1337672A - Devices and methods for forming air-fuel mixtures - Google Patents

Abstract

1337672 Spray carburetters W C JORDAN and V M LUND 18 Jan 1971 2333/71 Heading F1B Vapourization of fuel droplets in an air-fuel mixture is enhanced by positioning an electricallypowered radiant heater in the mixture path, the amount of power supplied to the heater being adjusted to provide maximum vapourization of the fuel with minimum heating of the air. A carburetter 17 having two main flow passages 23 and 24 and two auxiliary passages 25 and 26 (not shown on Fig.3) has throttle valves 27 and 28 in the main passages and similar throttle valves in the auxiliary passages. Tubular heaters 43 and 44 are provided in the main passages and similar heaters in the auxiliary passages. Electrical supply leads for the heaters are secured by a clip 56 to a bolt 18, which receives a wing nut to secure the cover of an annular air filter, the base 14 of which is mounted on the carburetter body. Additional holes are drilled through the base of the air filter to increase the amount of air which can be drawn in. A venturi 37 is supported in each passageway, by an arm having an internal passageway through which fuel is fed, and a choke valve 35 extends across both passageways. The lower ends of the heaters are spaced about “in. above the throttle valves and create a radiant heating zone in which the relatively highly absorbent fuel droplets are rapidly vapourized, the air, having a lower absorption characteristic, being heated less. The optimum condition is that in which the power supplied causes complete vapourization of the fuel without heating the air, and this provides the maximum improvement in torque and acceleration. The heaters are wired so that they can be switched on independently of the ignition circuit of the engine, in order to facilitate cold starting, but run continuously when the ignition circuit is energized. The optimum value of electrical current is determined by noting the time taken for a vehicle to accelerate from one predetermined speed to another when the throttle is moved to the fully open position from a predetermined partially open position. In a modification the heaters are annular and form part of the flow passage immediately downstream of the throttle valves. Alternatively the heaters can be positioned adjacent the inlet valves.