| 摘要 |
An apparatus and a method for accurately detecting degradation in performance of a NOx catalyst which serves to reduce NOx exhausted from a diesel engine. Thus an apparatus for detecting deterioration of a NOx by catalyst in a diesel engine, which supplies hydrocarbon for reduction into an exhaust pipe to reduce and purify an exhausted NOx by means of an NOx catalyst, comprises a sensor (4) for revolution of the diesel engine (1), a sensor (5) for a load on the diesel engine (1), a hydrocarbon sensor (11) provided rearwardly of a NOx catalyst (3) for detecting an amount of hydrocarbon in an exhaust gas, and deterioration detecting means (12) for detecting an operating condition of the diesel engine (1) on the basis of signals from the revolution sensor (4) and the load sensor (5) and determining deterioration of the NOx catalyst (3) on the basis of a change in an amount of hydrocarbon in the exhaust gas with the passage of time when the operating condition meets a predetermined condition. When deterioration of the NOx catalyst (3) is detected, it is possible to increase and add a reducer fuel.
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