CHARGE STRATIFICATION IN A TWO-STROKE ENGINE

摘要

A two-cycle internal combustion engine comprises a cylinder head having an intake port and exhaust port opened to a combustion chamber, to which compressed fresh air is introduced via an intake valve. The intake and exhaust valves are operated in response to a crank angle. A pulsation pressure of exhaust gas in the exhaust port is substantially restrained during an idling or light load running condition. The exhaust valve is opened earlier than the intake valve when the speed of the downward movement of the piston is relatively high, such that a part of exhaust gas in the exhaust port flows back to the combustion chamber in that condition. An exhaust gas swirl rotating around a cylinder axis is formed when the exhaust gas flows back and the fresh air is slowly introduced onto the exhaust gas swirl in that condition.