| 摘要 |
PURPOSE:To set lower a setting lower limit value of swirl ratio while maintaining stability of the swirl ratio and increase an intake air quantity by providing a slope on the run-up part on the lower face of an intake port so as to direct the intake air flow downward. CONSTITUTION:In a cylinder head H showing an intake air swirl port form of a direct injection engine, an intake port 1 adjusts the swirl ratio by the projection of a port helical part. A slope A is provided on the run-up part B of the intake port. The intake air once ascends the slope A in the stage of the run-up part B, then descends so as to be directed downward, passes through an intake valve hole 2, and directly enters a cylinder liner. In this way, the swirl ratio can be set low. A throat part C is ordinarily constituted, without providing a cut-off part on the throat part C.
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