Principles of solid state oxygen sensors for lean combustion gas control

This paper gives an overview about oxygen sensors for automotive applications to control the air-fuel ratio in order to reduce emissions and fuel consumption. The three-way catalyst system (TWC) using the potentiometric sensors based on zirconia represents the most effective system for the emission control at this time. New control strategies with linear lambda control at lambda = 1, for direct injection engines and other lean burn engines operating with excess air (lambda > 1) need alternative sensor concepts. Hence, current limiting electrochemical pumping cells (amperometric sensors) based on zirconia have been developed for engine control applications. As a future option we present also new research works in resistive type oxygen sensors based on semiconducting metal oxides. (C) 2001 Elsevier Science Ltd. All rights reserved.