Patent ID: 9732657
Date: 2017-08-15
CPC Classifications: F01N,F02D,G01N

Claim:
1. An oxygen sensor controller for an electromotive force-type oxygen sensor disposed in an exhaust passage of an internal combustion engine, the oxygen sensor comprising: a solid electrolyte; an atmosphere electrode that is disposed on one face side of the solid electrolyte and contacts with atmosphere when disposed in the exhaust passage; and an exhaust electrode that is disposed on a face on an opposite side to the one face of the solid electrolyte and contacts with exhaust gas when disposed in the exhaust passage, the oxygen sensor being configured to be subjected to an activation process that applies a unidirectional voltage between the atmosphere electrode and the exhaust electrode, and the oxygen sensor controller being configured to: apply a voltage in the same direction as the unidirectional voltage between the atmosphere electrode and the exhaust electrode in accordance with operating state of the internal combustion engine; detect a continuation time of rich operation that is a time in which an air-fuel ratio is rich relative to a theoretical air-fuel ratio during a predetermined operation period of the internal combustion engine; set a voltage application time period in accordance with the continuation time of rich operation; and in accordance with the voltage application time period set in accordance with the continuation time of rich operation, apply the unidirectional voltage between the atmosphere electrode and the exhaust electrode to make the atmosphere electrode positive and make the exhaust electrode negative.