| 摘要 |
<P>PROBLEM TO BE SOLVED: To measure an oxygen sensor element impedance without imparting excessive electric power to an oxygen sensor even in any value of the element impedance in the oxygen sensor, as to an oxygen sensor element impedance detector. <P>SOLUTION: A first switch element 22, a second resistance 26, a first resistance 30 and a first capacitor 31 are provided to impress a sweep voltage to the oxygen sensor 10. The first switch element 22 is turned on to impress the sweep voltage, so as to detect a sensor current I flowing in the oxygen sensor in accompaniment to the impression. The element impedance is calculated based on the sweep voltage and the sensor current I. The second resistance 26, the first resistance 30 and the first capacitor 31 are connected to the oxygen sensor 10 so as to make a time constant of the sweep voltage high along in accompaniment with an increase of the element impedance Rs. <P>COPYRIGHT: (C)2004,JPO |
