INTERNAL COMBUSTION ENGINE OPERATED WHILE SWITCHING COMPRESSED SELF-IGNITION COMBUSTION AND SPARK IGNITION COMBUSTION

摘要

PROBLEM TO BE SOLVED: To suitably switch operating conditions of an internal combustion engine from compressed self-ignition operation to spark ignition operation.;SOLUTION: When the operating conditions are switched from the compressed self-ignition operation to the spark ignition operation according to increase of target torque, a quantity of fuel injection is once gradually increased in a condition of stratified spark ignition operation and air-fuel ratio of a fuel-air mixture is gradually decreased. Then, when the air-fuel ratio is decreased to a predetermined value, the operation is switched into the spark ignition operation while the air-fuel ratio is decreased to a theoretical air-fuel ratio at a stretch. Thus, the operating conditions can be stably switched by passing through the stratified spark ignition operation, and output torque is not rapidly increased and the operating conditions can be switched without sense of incongruity by switching the operating conditions while gradually increasing the fuel. Further, discharge of atmospheric pollutants such as nitrogen oxides is not increased by switching the air-fuel ratio to the theoretical air-fuel ratio at a stretch when the air-fuel ratio reaches predetermined air-fuel ratio.;COPYRIGHT: (C)2004,JPO