Patent ID: 6516772
Filing Date: 2003-02-11
Classification: F02B,F02D,F02M,Y02T

Abstract:
A system for controlling combustion state of an internal combustion engine in which gasoline fuel is directly injected into cylinder combustion chambers, comprising:an air/fuel ratio sensor for detecting an air/fuel ratio of exhaust gas exhausted from the engine; engine operating condition detecting module which detects operating conditions of the engine including at least an engine speed and an engine load; fuel injection amount calculating module which calculates a basic fuel injection amount based on at least the engine speed and the engine load of the detected engine operating conditions and corrects the basic fuel injection amount, such that an error between the detected air/fuel ratio and a desired air/fuel ratio decreases, to determine an output fuel injection amount to be injected into the cylinder combustion chambers of the engine; ignition timing calculating module which calculates an ignition timing based on at least the engine speed and the engine load of the detected engine operating conditions to ignite a mixture of the injected fuel and air drawn through an air intake system and flowing into the cylinder combustion chambers; EGR flow rate regulating module which regulates an EGR flow rate of the exhaust gas recirculated through a pipe connecting an exhaust system and an air intake system of the engine; and purge flow rate regulating module which regulates a purge flow rate of vaporized fuel to be purged through a pipe connecting a canister and the air intake system of the engine; operation mode selecting module which selects one of lean-burn operation modes comprising a stratified combustion operation mode in which the desired air/fuel ratio is set to be a lean value; and a pre-mixture combustion operation mode in which the desired air/fuel ratio is set to be a value less lean than that of the stratified combustion mode; and combustion state control module which conducts a control to suppress degradation of combustion state, if it is determined to be degraded, by changing the desired air/fuel ratio, the EGR flow rate and the ignition timing when the engine is operated in the stratified combustion operation mode, while changing the desired air/fuel ratio, the EGR flow rate and the purge flow rate when the engine is operated in the pre-mixture combustion operation mode.