With the production mannered null piston peripheral face

摘要

PROBLEM TO BE SOLVED: To provide a blow-back suppressing structure having simple construction for surely suppressing blow-back over a long period.;SOLUTION: An engine has a top land space 31 partitioned at its lower end with a top ring 21 of a piston 5, a second land space 33 partitioned at its upper and lower ends with the top ring 21 and a second ring 23, and a third ring space 35 partitioned at its upper and lower ends with the second ring 23 and an oil ring 25, which are all formed between the outer peripheral face of the piston 5 and the inner peripheral face of a cylinder 3. A recessed portion 41 is provided on the inner peripheral face of the cylinder 3 for communicating the second land space 33 with the third land space 35 near the bottom dead center of the piston 5.;COPYRIGHT: (C)2005,JPO&NCIPI