TWO-CYCLE ENGINE HAVING STEPPED PISTON

摘要

PROBLEM TO BE SOLVED: To provide a two-cycle engine having a stepped piston capable of effectively preventing a blow-by phenomenon of mixture even with a simple and inexpensive constitution. SOLUTION: A two-step piston 10 having a small diameter part 10a and a large diameter part 10b is fitted to a two-step cylinder 1 having a small diameter part 1a and a large diameter part 1b, so as to form an annular subsidiary chamber 11 between the cylinder 1 and the small diameter part 10a of the piston 10. This engine comprises an air passage 24 introducing air mixed with oil into a crank chamber 29; a mixture passage 21 introducing the mixture to the subsidiary chamber 11; a scavenging passage 30 supplying the air in the crank chamber 29 to a combustion chamber 2; and an injection passage 70 injecting the mixture in the subsidiary chamber 11 from an inner periphery of the cylinder 1 upwards inclinedly to the combustion chamber 2. COPYRIGHT: (C)2004,JPO