| 摘要 |
PURPOSE:To improve engine performance while preventing NOx concentration from being increased by detecting temperature of cooling water at a cylinder head part, and thereby advancing or delaying fuel injection timing corresponding to changes of the temperature of the cooling water such that the NOx concentration in exhaust gas reaches a prescribed value. CONSTITUTION:Reference injection timing theta0 slightly delayed from optimum timing is set which provides a most preferable combustion state as well as a prescribed value of NOx concentration less than a specified value. Further, temperature of cooling water (reference temperature of cooling water) at a cylinder head part 5 is set in a case where an engine is ideally operated by fuel injected at said timing theta0. Hereby, an operation region at the reference injection timing theta0 is brought into a region A being advantageous in performance. Upon operation of the engine, engine rpm as well as output torque are detected, whereby it is judged whether or not a present operation state belongs to the region A. If NO, a difference DELTAT between the reference temperature T0 of the cooling water and actual temperature T of the cooling water is evaluated. If T>T0, the reference injection timing theta0 is delayed, while if T<T0 the reference injection timing theta0 is advanced. |
