Cylinder Individual AFR Estimation based on a Physical Model and using Kalman Filters

On diesel engines, a discrepancy between the air fuel ratio (AFR) of the cylinders can lead to a decrease of full load performances, an increase of pollutant and noise emissions and has an effect on the aftertreatment efficiency. A cylinder individual AFR estimator has been developed using Kalman filter techniques. This estimator is based on a physical model of the exhaust, and intended to be implemented in an engine management system. The time delay of the exhaust system, including the sensor, can be identified online. When applied on testbed acquisitions, the estimator gives good results over the whole operating range of the engine.