摘要 |
A piston 1 is employed in an engine 50 where a tumble flow is generated within a combustion chamber 53. The piston 1 includes: a top ring channel 3; and a portion 10 of an outer circumferential portion of a top surface, the portion 10 positioned opposite to an adjacent cylinder of the engine 50, the portion 10 having a raised shape so as not to expose a position P, of a bore wall surface, facing the top ring channel 3 face in the top dead center during at least a period from a time when the piston 1 is positioned at a compression top dead center to a time when a quantity of heat transfer in the combustion chamber 53 is the highest.
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