Patent ID: 6334425
Filing Date: 2002-01-01
Classification: F02D

Abstract:
A system for controlling an air/fuel ratio for a direct injection spark ignition engine which is operated at one of two combustion forms including an ultra-lean burn combustion and a pre-mixture charged combustion; comprising:engine operating condition detecting means for detecting operating conditions of the engine at least including an engine speed and an engine load; basic fuel injection amount determining means for determining a basic fuel injection amount based at least on the detected engine speed and the engine load of the engine operating conditions; desired air/fuel ratio determining means for determining a desired air/fuel ratio of exhaust gas produced by the engine; combustion form discriminating means for discriminating at which form of combustion the engine is operated; charging efficiency correction coefficient determining means for determining a charging efficiency correction coefficient for adjusting a charging efficiency of intake air based at least on the determined desired air/fuel ratio and the form of combustion at which the engine is operated; desired air/fuel ratio correcting means for correcting the desired air/fuel ratio based on the determined charging efficiency correction coefficient; output fuel injection amount determining means for determining an output fuel injection amount by correcting the basic fuel injection amount at least by the corrected desired air/fuel ratio; and fuel injecting means for injecting fuel into a cylinder of the engine based on the determined output fuel injection amount.