Cooperated control of multi stage injection system for direct injection gasoline engine

Direct injection gasoline engine has been developed to improve performance and fuel economy of engine. Furthermore, multi stage injection system can reduces emission, and provides better performance and fuel economy than single stage. Current injectors of direct injection gasoline engine have the limitation of injection duration. The injection ratio of multi injection and secondary one cannot be changed continuously. Consequently, the torque difference occurs when the injection ratio is changed in step shape. A two-step control using air device and ignition timing is developed to avoid this phenomenon. In this paper, the novel decoupled control for three-input one-output system is designed on the basis of previous cooperated idle speed control in order to achieve a good drivability. The control cooperates ignition timing and air device according to change injection ratio