TWO-CYCLE ENGINE

摘要

A two-cycle engine (1) comprising an ignition device (8), an exhaust control valve (24), and a control device (40) for controlling the ignition device (8) and the exhaust control valve (24). The control device (40) controllably operates the ignition device (8) for spark ignition and burning in a high load area, and in a low load area, controllably regulates a pressure in a cylinder chamber (3a) by adjusting the opening of an exhaust port (21) to self-ignite and burn an air-fuel mixture in a combustion chamber (10). A stratified air-fuel mixture field in which air and fuel are largely distributed at the center part (10c) of the combustion chamber (10) and burned gases remaining in the combustion chamber (10) are largely distributed on the outside (10b) of the center part of the combustion chamber (10) is formed in a low load/low rotational speed range. In the low load/low rotational speed range, the stratified air-fuel mixture field is formed to self-ignite and burn the air-fuel mixture.