Two-cycle combustion engine having two-staged piston

摘要

A two-cycle combustion engine having a two-staged piston, is simple in structure and inexpensive and addresses a undesirable blow-off phenomenon of the air-fuel mixture. The two-cycle combustion engine includes a cylinder block having a two-staged cylinder bore with a reduced diameter bore portion and a large diameter bore portion, and a two-staged piston having a reduced diameter piston portion and a large diameter piston portion. An annular auxiliary chamber is defined between the two-staged cylinder bore and the reduced diameter piston portion. The two-cycle combustion engine also includes an air-fuel mixture passage for introducing the air-fuel mixture into a crank member, an air passage for introducing air into the auxiliary chamber, a scavenge passage for supplying the air-fuel mixture within the crank chamber into a combustion chamber, and injection passages and for injecting the air within the auxiliary chamber into the combustion chamber to counter a press-out issue.