Oxygen concentration sensor

摘要

An oxygen concentration sensor has a solid-electrolyte element (2) which is capable of conducting oxygen ions and which has a first surface exposed to an exhaust gas and a second surface exposed to the atmosphere. The first and second electrodes (5, 4) are each deposited as layers on the first and second surface of the solid-electrolyte element (2). Application of a voltage between the electrodes (5, 4) generates a saturation current between the electrodes which corresponds to the oxygen gas concentration in the exhaust gas. On the other hand, a back electromotive force is generated between said electrodes if an air/fuel ratio in the exhaust gas does not exceed a stoichiometric air/fuel ratio. The device determines the oxygen gas concentration in the exhaust gas from the value of the current flowing between the electrodes (5, 4) by applying a constant voltage which does not exceed the level of the back electromotive force. <IMAGE>