Patent Number: 6,309,536

Title: Method and apparatus for detecting a functional condition on an NOxocclusion catalyst

Abstract: A method and apparatus for detecting a functional condition of an NOxocclusion catalyst using an NOx sensor. In order to compensate forvariations in oxygen concentration of the exhaust gas which wouldotherwise affect the detected NOx concentration downstream of the NOxocclusion catalyst, a relative value is calculated as the differencebetween the detected NOx concentration and the value of the detected NOxconcentration initially after start of operation control of an internalcombustion engine at a lean air-fuel ratio. The occlusion capability ofthe NOx occlusion catalyst is judged to have deteriorated when an increasein the relative value exceeds a predetermined value. On the other hand,the NOx occlusion catalyst is judged to have suffered an anomaly when therate of increase in the relative value becomes greater than apredetermined allowable value.

Inventors: Inagaki; Hirosi (Aichi, JP), Kondo; Noriaki (Aichi, JP), Miyata; Shigeru (Aichi, JP)

Assignee:

International Classification:

Expiration Date: 10/32013