Efficient lightweight two=stroke internal combustion engine

摘要

The two-stroke engine is especially for a hand-held tool, e.g. a chain saw. It has a single cylinder with a combustion chamber (4) over a flat-topped piston (7). Entry of fresh mixture and removal of exhaust gases is controlled by ports near the base of the cylinder. There is an inlet port (11) bringing mixture from the carburettor to the crankcase, from whence it may pass via transfer channels (20,30) to the cylinder. The transfer ports are angled to impart a swirling motion to the incoming mixture. The cylinder inlet ports (21,31) are angled away from the exhaust port (8) and exhaust channel (9), and the sharp edges of these inlet ports are chamfered (26,36).