US Patent 7331325 Direct-injection spark-ignition internal combustion engine

When an engine is in transitional operation, combustion is carried out by spray guide method. Further, when catalyst temperature T is high, namely, equal to or higher than a specified maximum temperature T1, stratified charge combustion by spray guide method is carried out, and when the catalyst temperature T is low, namely, equal to or lower than a specified minimum temperature T2, stratified charge combustion by wall guide method is carried out.