| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent excessive correction in an air-fuel ratio closed loop control by overshoot of sensor output when an air-fuel ratio sensor is activated. <P>SOLUTION: After an internal combustion engine is cool-started, the sensor output is raised or lowered together with the temperature rise of the air-fuel ratio sensor. When the sensor output is not less than an activation judgement upper limit or not more than an activation judgement lower limit, an activation judgement flag 1 is made to "1". Thereafter, the sensor output is overshot, but a variation volume ΔAFS of a sensor output AFS is obtained every calculation timing. When such a condition that its absolute value is not more than a predetermined judgement value continues n-times, it is regarded that the overshoot is completed and the sensor output is stabilized, an activation judgement flag 2 is made to "1", so as to start a closed loop control. Under conditions of n-time continuance, even if the variation volume ΔAFS becomes small near a peak of the overshoot, misjudgment does not occur. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
