| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an intake and exhaust device for a multi-cylinder engine that can improve engine torque and fuel economy performance with a simple configuration. <P>SOLUTION: The intake and exhaust device for the multi-cylinder engine includes a throttle part 53 interposed between independent exhaust passages 52 and a collecting part 58, and switching means 56, 56b, 56c capable of switching the state of the throttle part 53 into an independent flow state of partitioning the throttle part into a plurality of gas passing spaces 57 individually communicating with the respective independent exhaust passages 52, and a communicating state in which the gas passing spaces 57 communicate with one another. The gas passing spaces 57 are shaped to be smaller in passage area downstream than upstream. In a first operating region A1 including a low-speed high-load region, the valve opening period of an intake valve 19 and that of an exhaust valve 20 overlap with each other, exhaust valves 20 of other cylinders are opened during an overlap period, and the spaces in the throttle part 53 are placed in the independent flow state. In a second operating region A2 including a high-speed high-load region, the spaces in the throttle part 53 are placed in the communicating state. <P>COPYRIGHT: (C)2013,JPO&INPIT |
