Research And Applications Of Combustion Closed-Loop Control System For Diesel Engines

Energy crisis and environmental concern would require a more efficient andcleaner solution for automotive industry. Diesel Engine already has its advantage in thehigh combustion efficiency. But it has unsatisfactory emission issue. HCCI combus-tion technology provides the potential to reduce PM and NOx emissions dramaticallysimultaneously. But the problems of unstable combustion and narrow operating rangeprevent it from pratical use. In recent years, with the use of mass production type in-cylinder pressure sensor, combustion closed-loop control is becoming a key platformtechnology to support HCCI combustion. In this thesis, based on the first generation ofin-cylinder Combustion Analysis Tool (iCAT), the new combustion closed-loop con-trol system is developped. Two applications on the new platform are investigated: cyl-pressure based fuel injection method and combustion closed-loop control under enginestart conditions.The new generation of iCAT is redesigned in hardware and software. iCAT ac-quires and processes the cylinder pressure information from 4 in-cylinder pressuresensors. Combustion indices are calculated and delivered to ECU through CAN busor BDM communication. Closed-loop control is accomplished in ECU based on thisfeedback information. From the comparison tests with professional Combustion Anal-ysis System (CAS), the calculation accuracy of important combustion indices fromiCAT is verified.Based on the new combustion closed-loop control platform, a cyl-pressure basedfuel injection method is investigated. Cylinder identification and crank angle estima-tion with cylinder pressure are analysed in theory. Max. motoring pressure model isused to estimate the crank angle. Experimental result shows, cylinder identificationcan be achieved using cylinder pressure in a simple and robust mannor; crank angleestimation can provide a precision of within 1°CA for fuel injection.Combustion closed-loop control is applied in engine start process. Through an engine start model, the engine start feedback control algorithm is designed. From ex-perimental validation, the algorithm is proved to be effective in tracking a predefineddesired speed-up curve at didderent conditions. Injection parameters in each cylinderwould be adjusted individually according to the corresponding combustion state. Cali-bration e?ort can be notably reduced. The robust ability of engine start-up is enhancedwhile unnecessary fuel consumption is avoided and pollutant emissions are suppressed.