| 摘要 |
A high precision deterioration determination device for an exhaust gas purifier of an engine is provided. The engine includes an exhaust gas purifier disposed in an exhaust pipe of the engine, and a downstream exhaust gas sensor disposed in the exhaust pipe on the downstream of the purifier for generating outputs corresponding to components of an exhaust gas. The electronic control unit controls an air/fuel ratio of the engine to a predetermined value based on the outputs of the downstream exhaust gas sensor. The control unit is programmed to perform a non-linear filtering to extract rectangle-shaped waveform components from the outputs of the downstream exhaust gas sensor. The control unit subtracts the rectangle-shaped waveform components from the sensor outputs to extract noise components representing a degree of the catalyst deterioration.
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