| 摘要 |
PURPOSE: To suppress the increase of NOX even when the acceleration is performed from middle-high rotational frequencies and the like, by preparing an EGR valve forced OFF time map newly other than an EGR valve control map used in normal EGR control, and applying the EGR valve forced OFF time map preferentially. CONSTITUTION: During the engine operating time, a controller 7 reads the outputs of an accelerator opening sensor 8 and an engine rotational frequency sensor 2, and the time measuring is started by a timer 7-1. After a specific time Δt has passed, the accelerator opening at the time Δt passed is read, so as to calculate the accelerator opening change rate. Then, this accelerator opening change rate ad the engine rotational frequency are applied to the EGR valve forced OFF time map, so as to find the EGR valve forced OFF time T. Then, it is checked whether the time T is larger than 0 or not, and when T=0, a normal EGR control according to the EGR valve control map is carried out. On the other hand, when T>0, control to forcibly shut OFF the EGR valve 9 only for that time is carried out. |
