| 摘要 |
PURPOSE:To secure such suction charging efficiency that smoothly varies over the whole engine speed range, by making a sectional area of an independent suction passage to be installed in each cylinder in a part at the more upstream side than branch part for an interconnecting part interconnecting the said passage mutually, smaller than that in a part at the downstream side. CONSTITUTION:In case of a suction device which connects a suction port 4 of each cylinder 2 to a suction expansion chamber 9 extending in a cylinder train direction interconnectedly via each suction passage 8, an interconnecting passage 14 interconnecting each of independent suction passages 8 mutually to the point midway in each independent suction passage 8 via a branch passage 13 extending in parallel with the suction expansion chamber 10 and being branched off from each independent suction passage 8. At each branch passage 13, there is provided with an on-off valve 15 which is opened at a high speed range where an engine speed is more than the specified value, side by side. And, each independent suction passage 8 is formed into a flat form making length in the cylinder train direction a long diameter over the whole, while a sectional area in a part 8a at the more upstream side than a branch part for the interconnecting part 14 should be set to be smaller than that in a pat 8b at the downstream.
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