GB1081153A - Improved two-stroke internal combustion engine - Google Patents

Abstract

1,081,153. Charging two-stroke engines. K.T.J. HENRIKSON. Jan. 21, 1966, No. 2904/66. Heading F1B. In a two-stroke I. C. engine in which the crankchamber acts as a scavenging compressor, the compressed gases flowing through the transfer passage 10, Fig.1 emerge from nozzles 11, Fig. 4 (not shown) to induce ambient air from inlet 12 thereby increasing the volume of scavenging gas. Each nozzle 11 is directed into a separate outlet passage 14 which communicates with inlet ports 15. The outlet duct 17 opens into an expansion chamber (not shown) to reduce back pressure. Fuel/air mixture is drawn into the cylinder through a carburetter 20, a throttle valve 21 and'a pistoncontrolled inlet port 7. After crank-chamber compression the mixture passes via piston port 8, cylinder port 9, Fig. 2 (not shown) into transfer passage 10. At T. D. C. position piston ports 23 register with inlet ports 15 whereby the remaining mixture in passage 14 is inducted back into the crank-chamber 5 and the passage 14 is filled with ambient air. On the subsequent piston stroke the ambient air in passage 14 enters the combustion chamber 3 before the mixture thereby, scavenging the chamber with minimum loss of mixture via the outlet passage. In modifications, a compression-ignition engine uses a fuel injector 18, igniter 19 being omitted and a valve 24 controls the transfer passage 10. In another embodiment air enters the crankchamber 5, Fig. 3 of a fuel injection engine via a non-return valve 26 controlling an inlet passage 25. Compressed air leaves the crank-chamber directly via a non-return valve 27 controlling an outlet passage 28 which connects with the transfer passage 10. A further non-return valve 29 prevents escape of gases through the inlet passage 12. The valve 27 may be biased to open suddenly when the crank-chamber pressure is near its maximum. In a modification the engine is arranged for spark ignition in a similar manner to Fig. 1. In a further modification of Fig. 3 all air is admitted via the nozzles 11, valve 27 being replaced by a double-acting valve which permits air induction through duct 10 whilst there is a partial vacuum in the crank-chamber and then closes until almost maximum gas pressure is obtained. The valve is then reopened to cause the jet pump to induce additional air.