| 摘要 |
PROBLEM TO BE SOLVED: To detect the failure of an exhaust circulation controlling device accurately with a simple structure. SOLUTION: Based on the detection results of an operation-condition detecting means A which detects engine operation conditions an air-intake pressure is calculated by an air-intake pressure calculating means B, an exhaust pressure is calculated by an exhaust pressure calculating means C, and a target exhaust circulation rate is set by a target exhaust circulate rate creating means D. Also, the open limit of an exhaust circulate valve is controlled by an circulate valve controlling means E responding to the air-intake pressure, the exhaust pressure, and a target exhaust circulate rate. At the same time, providing an circulate valve open limit detecting means F which detects an actual open limit of the exhaust circulation valve, from these actual open limit of the exhaust circulate valve, the air-intake pressure and the exhaust pressure, an exhaust circulate rate is calculated by an exhaust circulate rate calculating means G. Based on the comparison between the target exhaust circulate rate and the calculated exhaust circulate rate, the presence or absence of a failure of exhaust influx rate controlling device is judged by a failure judging means H. |
