| 摘要 |
PROBLEM TO BE SOLVED: To generate a tumble stronger than a cylindrical tumble. SOLUTION: A cylinder-direct fuel injection type spark ignition engine determines an intake inflow angle of intake ports to a combustion chamber 6 and a form of a cavity 25 defined in a piston crown so that a tumble is generated in intake air flowing into the combustion chamber 6 from openings of the intake ports to the combustion chamber 6 and that fuel injected from a fuel injection valve 12 is entrained on the tumble and delivered near to a spark plug 7 positioned substantially in the center of a combustion chamber ceiling. The form of the cavity 25 is set so that in a section passing a nozzle hole point of the fuel injection valve 12 and a fire point of the spark plug 7, the tumble has an elliptic form with a major axis in a stroke direction of a piston 5.
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