| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device that properly adjusts oxygen concentration of an exhaust gas even when an output value of an oxygen concentration sensor indicates hysteresis. <P>SOLUTION: An air-fuel ratio controller controls air-fuel ratio to change oxygen concentration of the exhaust gas on the basis of a rate of change of the output value of the sensor, when the output value Voxs of the oxygen concentration sensor is a value between a low-side threshold Loth and a high-side threshold Hith, the low-side threshold Loth being smaller than a central value which is a substantially intermediate value between the maximum output value and the minimum output value of the sensor as well as larger than the minimum output value, and the high-side threshold Hith being larger than the central value as well as smaller than the maximum output value. Furthermore, when the output value of the sensor is the low-side threshold Loth or smaller, or the high-side threshold Hith or higher, the controller controls air-fuel ratio to change oxygen concentration of the exhaust gas on the basis of the output value Voxs of the sensor. <P>COPYRIGHT: (C)2012,JPO&INPIT |
