Patent ID: 9261001
Filing Date: 2016-02-16
CPC Classification: B01D,F01N,Y02A,Y02T

Claim Text:
1. A failure determination system of exhaust gas purification apparatus comprising: a NOx selective catalytic reduction catalyst that is disposed in an exhaust passage of an internal combustion engine and uses ammonia as a reducing agent; a reducing agent supply unit that supplies ammonia or a precursor of ammonia into exhaust gas flowing into the NOx selective catalytic reduction catalyst at a location upstream from the NOx selective catalytic reduction catalyst; and a NOx sensor that is disposed downstream from the NOx selective catalytic reduction catalyst and detects NOx in exhaust gas flowing out of the NOx selective catalytic reduction catalyst, wherein the failure determination system of exhaust gas purification apparatus further comprises an electronic control unit configured to: perform failure determination of the exhaust gas purification apparatus based on a detected value of the NOx sensor; provide an indication to a vehicle operator when the exhaust gas purification apparatus is determined to be in a predefined failure state; calculate an adsorption amount difference at assumed failure, the adsorption amount difference at assumed failure being a difference between an ammonia equilibrium adsorption amount in the NOx selective catalytic reduction catalyst in an equilibrium state of ammonia adsorption, assuming that the exhaust gas purification apparatus is in the predefined failure state, and an actual ammonia adsorption amount in the NOx selective catalytic reduction catalyst; and restrict use of the detected value of the NOx sensor in the failure determination or inhibit the failure determination itself, when the calculated adsorption amount difference at assumed failure exceeds a predetermined value.