Patent ID: 6244241
Filing Date: 2001-06-12
Classification: F02D,Y02T

Abstract:
A fuel injection control system, for a direct injection-spark ignition type of engine equipped with an injector operative to spray fuel directly into a combustion chamber of the engine, which determines an injection pulse width corresponding to a given quantity of fuel with which the injector is kept open to spray said quantity of fuel, controls the injector to spray fuel through a compression stroke while the engine operates with lower engine loads in an engine operating zone specified for lean stratified charge combustion so that the fuel is stratified around an ignition plug to cause lean stratified charge combustion to, thereby, provide an air-fuel ratio greater than a stoichiometric air-fuel ratio, said fuel injection control system comprising:an oxygen sensor operative to monitor the oxygen content of an exhaust gas to detect an air-fuel ratio; andcontrol means for executing fuel injection feedback control to control said quantity of fuel injection based on said air-fuel ratio detected by said oxygen sensor, causing the injector to spray fuel through a plurality of intake stroke split injections in a specified engine operating zone in which said fuel injection feedback control is performed to maintain at least an approximately stoichiometric air-fuel ratio while the engine operates with lower loads, determining a fuel injection quantity characteristic of the injector with respect to injection pulse width for each said intake stroke split injection based on a value controlled by the fuel injection feedback control during execution of the intake stroke split injection to determine a learning correction value, and making said learning correction value reflect on said control of the quantity of fuel in a minute injection quantity zone specified within said specified engine operating zone for said lean stratified charge combustion.