Study on Response Characteristics of Switching Zirconia Oxygen Sensor for Air-Fuel Ratio Control

Abstract

The time delay between the changed quantity of the injected fuel and the detection of the resulting change of the air-fuel ratio determines the dynamic nature of the closed-loop control for air-fuel ratio, and the response delay of oxygen sensor itself is a main effect factor. The response characteristics of switching zirconia oxygen sensor will change and even deteriorate with the increasing service time of oxygen sensor. In this paper, the response characteristics of switching zirconia oxygen sensor and the impact of response slowing on air-fuel ratio and emissions are studied through engine bench test, the impact of response delay of switching zirconia oxygen sensor on air-fuel ratio control is analysed, and a new controller of air-fuel ratio based on discrete PI controller is proposed.