| 摘要 |
PURPOSE:To control recirculation of exhaust gas promptly and correctly, by executing feedback control having a plurality of correction speeds according to the deviation between the actual opening and an aimed opening of an exhaust- gas recirculation valve. CONSTITUTION:In case that the deviation l between the actual opening and an aimed opening of an exhaust-gas recirculation valve is smaller than -l1B, the exhaust-gas recirculation valve is lifted up in a quick mode. When the deviation becomes substantially equal to an aimed value and satisfies the following relationship, -l1B<l<l0, with increasing of the opening of the recirculation valve, a duty control for effecting intermittent ON-OFF switching of a valve SOL, B is executed to change the mode of lifting up the recirculation valve to a slow mode so that the actual valve opening may not overshoot the aimed value. Further, when the actual valve opening becomes near to the aimed value the deviation becomes smaller than a small tolerable range of + or -l0 with increasing of the valve lift, control of the exhaust-gas recirculation valve is completed by stopping lift correcting operation. |
