| 摘要 |
PURPOSE:To improve fuel consumption by fully opening an exhaust gas recirculation (EGR) valve when an engine operating state is within a fixed range where EGR is allowed, and fuelly closing the EGR valve when the engine operating state is out of the above-mentioned fixed range, and changing engine operating conditions according to the opening state of the EGR valve. CONSTITUTION:During the operation of an engine, a decision is given on whether intake pipe negative pressure obtained by an intake pressure sensor 16 is above a fixed value, namely the full open pressure of an EGR valve 26, or not. When the intake pipe negative pressure is above the fixed value, an EGR generating valve 30 is driven, and intake negative pressure is therefore introduced into the diaphragm chamber 26d of the EGR valve 26 to open it for starting EGR action. On the other hand, when the intake pipe negative pressure is not above the fixed value, the EGR generating valve 30 is opened toward atmospheric side for stopping EGR action. When EGR is in execution, fundamental fuel injection quantity is determined using a map M1 established for EGR being in execution on the outputs of the intake pressure sensor 16 and an engine speed sensor 34, and when EGR is in stoppage, the above- mentioned quantity is determined using a map M2 similarly established for EGR being in stoppage.
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