| 摘要 |
PURPOSE:To eliminate deviation of an actually controlled EGR (exhaust-gas recirculation) rate to an aimed value, by comparing the difference between the intake pressure under the state that EGR is carried out and under the state that EGR is not carried out with a reference value, and correcting an instruction value on the basis of the deviation between the actual pressure difference and the reference value. CONSTITUTION:In an intake passage 2 in an engine body 1, there are provided a pressure sensor 20 that is disposed downstreams of a throttle valve 6 for detecting the intake pressure and a temperature sensor 21 for detecting the temperature of intake air that is disposed on the downstream side of the position where an EGR passage 4 joins the intake passage 2. Further, a control circuit 25 is provided for controlling the EGR rate by way of open control, i.e., by selecting an aimed value from among preset EGR rates on the basis of signals representing the conditions of engine operation, and actuating the throttle valve 6 and an EGR valve by using the aimed EGR rate as in instruction value. |
