Exhaust gas purifying system for diesel engine

摘要

An exhaust gas purifying system, which is equipped with a catalytic converter having a NOx absorbent capable of absorbing NOx emissions in an excessively oxygen concentrated atmosphere and releasing NOx emissions absorbed therein in response to a drop in oxygen concentration of the exhaust gas, estimates a level of NOx absorption of the NOx absorbent and, when the level of NOx absorption has reached a predetermined level, while controlling an air-to-fuel ratio to converge at an approximately stoichiometric air-to-fuel ratio, divides the amount of fuel that is to be sprayed into two parts for early split fuel injection which is made at the beginning of an intake stroke and later split fuel injection which is made at an end of a compression stroke following the intake stroke. While the engine operates in a high engine load region, an intake throttle valve is closed so as to decrease the amount of intake air that is introduced into the engine.