Fuel limiting method in diesel engines having exhaust gas recirculation

摘要

A method of controlling the fuelling rate of a compression ignition engine having an exhaust gas recirculation system (EGR) (12) and a turbocharger (14). The method includes the steps of predicting the exhaust gas air/fuel ratio as a function engine operating characteristics and the operator-requested fuelling rate. This value is compared to an air/fuel limit value stored in a table of values indexed by engine operating characteristics. The air/fuel limit is the value below which visible smoke occurs. The predicted air/fuel ratio is compared to the air/fuel ratio limit and either (1) the fuel is delivered at the requested rate, (2) the start of injection timing is modified and the fuel is delivered at the requested rate or (3) the fuelling rate is limited as a function of the requested fuelling rate and measured or determined engine operating parameters.