Patent ID: 6257197
Filing Date: 2001-07-10
Classification: F02D,Y02T

Abstract:
An engine control system for a direct injection-spark ignition type of engine which is equipped with a fuel injector for spraying fuel directly into a combustion chamber and an exhaust system having a lean NOx conversion catalyst for lowering an emission level of nitrogen oxides (NOx) in exhaust gas at an air-fuel ratio of .lambda.>1 for controlling the engine to operate with a fuel charge of .lambda.>1 in a zone of partial engine loadings and with a fuel charge of .lambda..ltoreq.1 in a zone other than said partial engine loading zone, said engine control system comprising:engine operating condition monitoring means for monitoring engine operating conditions; andfuel injection control means for, while said engine operating condition monitoring means monitors an engine operating condition in said partial engine loading zone, dividing a given amount of fuel into two parts which are intermittently delivered through early and late split injection respectively in a intake stroke, and controlling said fuel injector such that a midpoint between points at which said early and late split injection are timed respectively to start is before a midpoint of a intake stroke.