| 摘要 |
PROBLEM TO BE SOLVED: To provide compatibility between safety in the stationary time and follow-up performance in the transient time by controlling the reference opening of an EGR valve, calculated according to the engine operating state so that the reference opening may be the weight-averaged opening by changing the weighting ratio in the stationary time and in the transient time to be judged on the basis of the differential pressure between exhaust system pressure and intake system pressure. SOLUTION: When an EGR valve 9 interposed in an EGR passage 10 for connecting an exhaust manifold 8 to an intake manifold 4 is controlled by a control unit 13, the reference opening of the EGR valve is calculated on the basis of the operating state of an engine, namely, the output of an air flow meter 16 and a rotational speed sensor 17. The weighting ratio in calculating of the opening of the EGR valve 9 by weighted average of the last weighted average value and the recently calculated reference opening is calculated according to the change of the engine operating state. The last weighted average value and the recently calculated reference opening value are weight-averaged on the basis of the weighting ratio, and the opening of the EGR valve 9 is so controlled as to be the weight-averaged EGR valve opening. |
