IN-CYLINDER INJECTION ENGINE CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To enable effective refreshing of an NOx-occluded lean NOx catalyst and, particularly, to enhance refreshing effect while keeping fuel economy from being aggravated. SOLUTION: This system is for a cylinder fuel injection type engine that is equipped with an injector 22 that directly injects fuel into a combustion chamber and a lean NOx catalyst. It is provided with an air-fuel ratio changing means that varies the air-fuel ratio that can range from those exceeding the stoichiometric air-fuel ratio to generally the stoichiometric air-fuel ratio or those below it and a control means 71 for refreshing the catalyst. When the air-fuel ratio is changed from the lean to the generally stoichiometric or richer ratio, the control means 71 splits fuel injection from the injector 22 into two shots as a catalyst refreshing control: a first injection that is started during an intake stroke and a second injection that is started during a mid-period of a compression stroke.