A deterioration diagnostic device for an exhaust gas purifier

The invention provides a deterioration diagnostic device for diagnosing a degradation condition of an exhaust gas purifier disposed in an exhaust passage in an engine based on a sensor value of an exhaust gas sensor that is disposed downstream of the purifier. The device includes detecting-signal ge...

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1. Verfasser: MAKI, HIDETAKA
Format: Patent
Sprache:eng ; fre ; ger
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Beschreibung
Zusammenfassung:The invention provides a deterioration diagnostic device for diagnosing a degradation condition of an exhaust gas purifier disposed in an exhaust passage in an engine based on a sensor value of an exhaust gas sensor that is disposed downstream of the purifier. The device includes detecting-signal generating unit for generating a detecting-signal having particular frequency components and multiplying the generated signal to a basic fuel injection amount so as to calculate a fuel injection amount and exhaust gas purifier evaluating means for extracting a frequency response corresponding to the detecting-signal from an output of the exhaust gas sensor of the engine, the output being in response to the calculated fuel injection amount, so as to determine a condition of the purifier based on the extracted frequency response.