| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for accurately detecting the deterioration conditions of a wide range air-fuel ratio sensor. <P>SOLUTION: A current is applied to an electromotive force cell 24 to detect a voltage V0 between electrodes (S10). Then, the application of the current is stopped (S16). After a lapse of 10μs to 1ms subsequent to the stoppage, the voltage drop Vsd1 between the electrodes on the both surfaces of the cell 24 is detected (S20), and a first resistance Rvs1 corresponding to the temperature of the cell 24 is detected from Vsd1 (S22). Then, after a lapse of 10ms to 50ms after the stoppage, a voltage drop Vsd2 of the cell 24 is detected (S26), and a second resistance Rvs2 corresponding to the internal resistance which includes the amount equivalent to the deterioration of the cell 24 is detected from the voltage drop Vsd2 (S28). Then, the deterioration condition of the wide range air/fuel ratio sensor is detected by comparing the resistance Rvs1 with the resistance Rvs2 (S30). <P>COPYRIGHT: (C)2004,JPO&NCIPI |
