Model Based Injection Mass Supervision for Diesel Engines Using a Fast Broadband Oxygen Sensor 2002-01-0846

Due to more severe exhaust gas regulations with sharper exhaust gas limitations and rising requirements for on-board diagnosis in this contribution a method for injection mass supervision in diesel engines using a fast broadband oxygen sensor will be presented. Based on a physical model the injected fuel mass can be determined by evaluating the measured air mass and oxygen concentration in the exhaust gas. Cylinder individual injection mass calculation becomes possible using an inverse model of the oxygen sensor dynamic. Thereby the sensor dynamic is specified by evaluating step responses of the oxygen concentration at jumps of the injection mass. For cylinder assignment the runtimes of the exhaust gas in the exhaust pipe have to be determined. They result from the calculation of the cross correlation function of the reconstructed fuel mass and measured mean indicated cylinder pressure. Comparing the calculated injection mass with the given nominal injection mass by the electronic diesel control (EDC) residuals for each cylinder can be established which are rather zero in the fault free case and differ from zero if a fault in injection mass preparation occurs.