EGO SENSOR-BASED ROBUST OUTPUT CONTROL OF EGR IN DIESEL-ENGINES

In diesel engines, exhaust gas recirculation (EGR) is an efficient met hod for reducing NOx. EGR rates are commonly set according to the expe cted engine behavior, without considering the actual composition of th e exhaust gases, In this paper, a new control system for EGR in passen ger cars is presented, based on an exhaust gas oxygen (EGO) sensor as indicator of the combustion state as well as on a robust design approa ch to cope with the parameter variations, The proposed control has bee n designed for and tested on an Audi TDI engine and has been found to yield a similar performance as the conventional controllers for the st andard engine, in spite of the transport delays between combustion pro cess and measurement, Due to the presence of feedback, reduced sensiti vity and/or detectability of wear, production irregularities, changes of operating conditions and calibration faults are expected from long- time measurements.