| 摘要 |
PROBLEM TO BE SOLVED: To secure an appropriate amount of fresh air while ensuring ignition performance when CI combustion is performed in a low-load area, and to prevent abnormal combustion when Si combustion is performed in high-load area.SOLUTION: An exhaust manifold 30 of an engine includes: a plurality of independent exhaust passages 31, 32, 33; a negative pressure generating device 35 commonly disposed downstream of the independent exhaust passages; bypass passages 41, 42, 43 bypassing the negative pressure generating device 35; and flow selector valves 45 disposed in respective bypass passages. In a first operating region where CI combustion is performed and a load is relatively low, an exhaust valve is opened not only at an exhaust stroke but also at an intake stroke, and the flow selector valve 45 is opened. In a region higher in load than a first predetermined load in the first operating region, an intake amount adjusting means is controlled so that a fresh air amount becomes larger as the load gets higher. On the other hand, in a second operating region where the SI combustion is performed and the load is relatively high, opening degree of the flow selector valve 45 is made smaller than that in the first operating region. |
