| 摘要 |
An inlet valve includes a valve head including a valve surface located at a circumferential edge portion, and a single annular circumferential edge groove disposed radially inside and close to the valve surface in the circumferential edge portion. When intake air (an airflow) proceeds along a surface of the valve head and reaches the circumferential edge portion, only a portion thereof (a partial airflow) enters the circumferential edge groove and the remaining thereof (remaining partial airflow) passes by the circumferential edge groove. As the intake air (the partial airflow) having entered the circumferential edge groove forms a turbulent flow, the intake air surrounds the circumferential edge portion of the valve head and reaches below the circumferential edge portion of the valve head, thereby achieving an increase in volume of air taken into a combustion chamber. Further, because only a portion of intake air enters the circumferential edge groove, it is possible to suppress and minimize flow resistance applied to air taken into the combustion chamber from an inlet port.
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