ABNORMALITY DETECTION DEVICE OF OXYGEN SENSOR

摘要

PROBLEM TO BE SOLVED: To provide an abnormality detection device of an oxygen sensor detecting suitably an abnormality.

SOLUTION: This abnormality detection device 1 of the oxygen sensor is equipped with: an exhaust side electrode 24 exposed in an exhaust passage of an internal combustion engine; an atmospheric layer formation member 16 for forming an atmospheric layer 18 conducting to the atmosphere through an atmospheric hole inside the exhaust passage; an atmospheric side electrode 22 exposed to the atmospheric layer 18; and an electrolyte layer 20 interposed between the exhaust side electrode 24 and the atmospheric side electrode 22 enabling movement oxygen ions between both electrodes. The device 1 is also equipped with: a reverse voltage application means for applying a reverse voltage so that the potential of the exhaust side electrode 24 becomes higher than the potential of the atmospheric side electrode 22 as much as a value necessary for moving oxygen more than an oxygen amount taken into the atmospheric layer 18 from the atmospheric hole, forcibly from the atmospheric side electrode 22 toward the exhaust side electrode 24 after an ignition is switched off; and an abnormality diagnosis means for diagnosing existence of an abnormality of the oxygen sensor 10 based on a reverse current flowing between the atmospheric side electrode 22 and the exhaust side electrode 24 following application of the reverse voltage.

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