Patent GB-474418-A (GB)
Title: Improvements in and relating to two-stroke cycle internal combustion engines
IPC: F02B25/00
Filed: 1936-04-27
Abstract: 474,418. Supplying fuel to two-stroke engines. RALSTON, G. April 27, 1936. No. 11867. [Classes 7 (iii) and 7 (vi)] [Also in Group XXVIII] Each of the cylinders of a multicylinder engine in which fuel is sprayed into the air inlet passages is provided with an air suction pump and an air pressure pump connected by a tube to a fuel chamber in which the level is maintained constant. After the suction pump has drawn a column of fuel into the tube, the pressure pump forces air upon the column of fuel which issues through a spraying nozzle. Air for scavenging and charging is supplied by a rotary blower to the piston controlled air inlet ports 5 and fuel is injected through nozzles 17 into the air entering the cylinders after the exhaust gases have been expelled through valves 250 in the cylinder head. The fuel feeding mechanism for all the nozzles is carried in a casing 87 mounted on the engine crank case. Each nozzle is connected by a U-tube 25 to a reservoir 49 in which fuel is maintained at a constant level by a common supply pipe 70 and an overflow device 89. While a mechanically or electrically controlled valve 114 in the nozzle 17 is held closed a valve 33 is opened by a cam 330 on a shaft 81 and fuel is drawn from the reservoir 49 past a non-return valve 921 by the suction of air created by a pump plunger 290 operated by a spring 291. After the valve 33 has been closed a cam-actuated bellcrank 294 operates the plunger 290 to expel the air drawn in during the suction stroke past a mechanically-operated valve 37 and through a port 45 leading to the atmosphere. The strokes of all pump phmgers 290 are adjusted simultaneously by a shaft 108 movable axially to vary the position of the levers 294 on their cams 295. The shaft 108 may be interconnected either with a slidably mounted camshaft 82 which controls the time at which the exhaust valves close and to a commutator 200 having a tapered contact surface 302 which controls solenoids 201 to vary the time at which the fuel valves 114 are opened or with a throttle valve in the blower outlet. During the suction stroke of the plunger 290 air is drawn from the atmosphere past a valve 179, Fig. 8, into a pump 71 by a plunger 300 and after a mechanically-operated valve 202 has been opened the plunger forces the air through a passage 79 into an air compression pump 75 and forces the fuel in the U -tube into a tube 21 leading to the nozzle 17. Towards the end of the compression stroke of the plunger 300 the pump 75 commences its delivery stroke and after the passage 79 has been closed the fuel valve 114 is opened. The displacement of the pump 75 is equal to the volume of the maximum quantity of fuel to be sprayed and the cam 175 operating the pump 75 imparts a constant speed to the plunger to maintain a constant air pressure behind the fuel in the tube 21. As the fuel supply is reduced and the opening of the fuel valve 114 delayed, the closing of the exhaust valve may be delayed to allow the excess of air to escape from the cylinder by sliding a cam shaft 82 longitudinally to move a cam 251 under a roller 253 carried by the exhaust valve rocker shaft 254. The cam always opens the exhaust valve at a constant time in the cycle. In a modified construction, the U-tube is replaced by a pipe depending into an extension of the pipe 93.