| 摘要 |
PURPOSE:To eliminate the need of providing a flow control valve respectively at every branch passage for thereby reducing an operational cost, by utilizing a single flow control valve in controlling the flow rate between a swirl forming passageway and a branch passage and a fluid diode in preventing the back flow of intake air through these passageways. CONSTITUTION:An intake air flows from a collecting portion 23 into respective combustion chambers, passing through respective branch portions 24, a fluid diode 27 and an intake port in this order. The intake air is also supplied into respective combustion chambers through a sub intake passage 26, and the flow rate of intake air passing through the sub intake passage 26 is controlled by opening and closing the collecting portion 3 by means of a flow control valve 25. During a small load operation, the flow control valve 25 is closed substantially completely to increase the flow of intake air passing through the sub intake passage 26 for forming a swirl inside the combustion chamber. The intake air may backflow into respective branch portions 24 instead of flowing correctly into respective cylinders, because intake valves are closed in cylinders running on strokes other than an intake stroke. Such a backfow is, however, suppressed for the presence of fluid diode which can provide a drag against the backflow. |
