Engine flameout process analysis

The piston stopping position directly impacts the next engine starting after engine flameout in idle stop system. The shutdown process of the gasoline direct injection (GDI) engine is studied by theory analysis and simulation experiments. The both mathematical model of the cylinder gas and crankshaft output torque are derived. The bench test system is designed for the GDI engine. By comparing the simulation and bench experiment, the torque and speed characteristics of the shutdown process are analyzed. The conclusion is derived that the distribution of the piston stopping at 60-80°CA before upper dead center is about 90%. The results show that the torque changes are approximate cycle attenuation process without considering the air leakage and other perturbation.