Patent ID: 9404832
Filing Date: 2016-08-02
CPC Classification: F01N,F02D,G01M,Y02T

Claim Text:
1. A degradation diagnosis device for an exhaust gas sensor provided downstream from a catalytic device in an exhaust-gas passage of an internal combustion engine, the degradation diagnosis device comprising: a diagnosis-period setting section configured to calculate an accumulation value by accumulating an intake-air quantity of the internal combustion engine from a start time of a diagnosis, and to terminate a diagnosis period when the accumulation value reaches an intake-air-quantity accumulation threshold value; a degradation judging section configured to judge whether the exhaust gas sensor is in a degraded state on the basis of a reversal number of an output of the exhaust gas sensor over the diagnosis period; and a threshold-value setting section configured to set the intake-air-quantity accumulation threshold value according to the intake-air quantity such that the intake-air-quantity accumulation threshold value becomes larger as the intake-air quantity becomes larger.