Exhaust Gas Flow Mixing Model and Application to Individual Cylinder A/F Estimation and Control*

This paper investigates a modeling approach for individual air-fuel ratio in engines with multi-cylinders. The input of the model is individual air-fuel ratio and the output is the measurement of air-fuel ratio at the gas mixing point in the exhaust manifold. The model is constructed by following the physics of exhaust gas flows and stochastic treatment. The model is validated by experimental results carried on an engine test bench. Furthermore, as application of the proposed model, an individual air-fuel ratio estimation method with online adjusting is presented and the individual air-fuel ratio is controlled via feedback of estimation by experiment.