AIR-FUEL RATIO DETECTING DEVICE FOR ENGINE

摘要

PROBLEM TO BE SOLVED: To accurately detect an air-fuel ratio even when a sensor output characteristic is changed caused by a change in temperature of an oxygen sensor, in a device detecting the air-fuel ratio by the linearization processing of an output of the oxygen sensor. SOLUTION: The electromotive force Es of the oxygen sensor of oxygen concentration cell type is converted into linearizing data having a linear characteristic with respect to the air-fuel ratio based on a predetermined linearization conversion formula, and the air-fuel ratio is detected based on the linearization data. A coefficient of the linearization formula is changed according to internal resistance Ri correlating with the temperature of the oxygen sensor.