| 摘要 |
PROBLEM TO BE SOLVED: To increase scavenging efficiency and charging efficiency and improve combustion property, by forming a cutout having an inclined face inclined in the same direction as an opening of a booster port at a portion opposite to the booster port of the upper surface of a stratified scavenging 2-cycle engine. SOLUTION: A opening portion 8a of a booster port 8 to a combustion chamber 5 is formed to have an inclined face at a smaller angleα1 to an inner face 1a of a cylinder 1 so as to smoothly flow mixture upward into the combustion chamber 5. On an upper surface 2a of a piston 2 and on a side opposite to the booster port 8, a cutout 9 is formed of an inclined face inclined from the upper surface 2a toward the same direction as the opening 8a of the booster port 8. An inclined angleβ1 is set to be equal to the inclined angleα1 of the booster port 8 or slightly lager than the inclined angleα1. Accordingly, a flow f1 flowing upward and a flow f2 flowing toward a central upper portion in the combustion chamber 5 can be generated in even balance.
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