| 摘要 |
PURPOSE:To reduce combustion noises and emission of NOx, by effecting pilot injection of fuel before main injection in a prescribed range of engine operation to inject fuel separately in two times, and thereby lowering the injection rate of fuel. CONSTITUTION:By driving signals S3, S4, a solenoid valve 44 is closed for a prescribed period theta2 after passing of a time theta1 from a reference point and also closed for a prescribed while theta4 after passing of a time theta3 (theta1+theta2<theta3) from the reference point. Main fuel injection is effected in the period theta4. At the time of no-load operation of an engine, on the other hand, pilot injection of fuel is effected by closing the solenoid valve 44 for the prescribed while theta2 after passing of a time theta1 from the reference point before effecting main fuel injection. By thus injecting fuel separately in two times at the time of no-load operation of the engine such as idling operation and thereby lowering the injection rate of fuel, it is enabled to burn fuel such that the combustion pressure does not have a sharp peak. |
