Parameters estimation of wall-wetting model and UEGO sensor for spark ignition engine

Accurate parameters estimation of wall-wetting model and Universal Exhaust Gas Oxygen (UEGO) is beneficial to Fuel-Air Ratio (FAR) control performance, when it is utilized to FAR controller design. In this paper, based on that the output of UEGO, air flow into cylinders and fuel injection flow are known, an adaptive parameters estimator is proposed. The dynamics of air flow into cylinders, wall-wetting effect, transportation delay and UEGO are analyzed; the math descriptions used for parameters estimation are given. The parameters estimator is divided into two steps, parameter of UEGO is estimated firstly and the parameters of wall-wetting model are estimated later, which can reduce the order of estimator. The convergence and influence factors of adaptive parameters estimator are analyzed, the approach to design estimator gains are also discussed. Simulation results indicate that the proposed method can estimate the parameters of wall-wetting model and UEGO accurately, which satisfies the parameters estimation demand of various operating condition.