| 摘要 |
PURPOSE:To form an optimum swirl over the whole operation range of an engine as well as to improve charging efficiency and combustibility either, by making a sense of a straight port direct little to a cylinder center, in case of an engine having a helical port to be normally opened and the straight port to be opened in time of high load. CONSTITUTION:Two suction ports 10 and 11 and one exhaust port 13 are all installed in one cylinder, and the suction port 10 is formed in spiral from and set down to a swirl port, while the suction port 11 is set down to a straight port. And, the swirl port 10 sucks air at the whole operation range from low load to high of an engine by the straight port 11 preforms suction air only in time of high load. Therefore, in time of low load, there is formed a strong swirl, while in the time of high load, a suction passage 9 of the straight port 11 is made to tilt toward the center of a cylinder 7 so that it works so as to cancel the strong swirl, thus improvements in stability in combustion and charging efficiency is promoted.
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