2-CYCLE UNI-FLOW SPARK-IGNITION ENGINE

摘要

A 2-cycle uni-flow spark-ignition engine has an annular scavenging chamber which is communicated with a crank chamber and which is connected to scavenging ports which are opened in an end period of downward stroking of a piston. A fluid introduced into the crank chamber is pre-compressed by the downward stroking of the engine and is discharged into a cylinder chamber through the annular scavenging chamber and the scavenging ports to form a uni-flow of scavenging fluid with a swirl above the piston. The engine has an exhaust valve provided on a cylinder head and normally opened by being driven with a predetermined force exerted by driving coiled spring towards the inside of the cylinder chamber. The exhaust valve is closed in the beginning period of compressing upward stroking of the piston so as to allow compression of the mixture introduced into the cylinder chamber and is automatically opened at the end period of expansion downward stroking of the piston after explosion and generation of power, so as to enable the combustion gas to be discharged as exhaust gas.