EVALUATION METHOD FOR DETERIORATION STATE OF HYDROCARBON ADSORBENT

摘要

PROBLEM TO BE SOLVED: To provide a method capable of accurately evaluating the deterioration state of a hydrocarbon adsorbent provided in an exhaust passage of an internal combustion engine with a relatively inexpensive constitution.

SOLUTION: A humidity sensor 21 is provided near the HC adsorbing material provided in an exhaust system of the engine. After stopping the operation of the engine 1, the deterioration state of the HC adsorbent 7 is evaluated based on a detection value of the humidity by the humidity sensor 21. The evaluation of the deterioration state is carried out by comparing the detection value of the humidity with a predetermined threshold value set corresponding to the temperature state near the HC adsorbent 7. At the time of evaluation of the deterioration state, an influence of variation of an output characteristic depending on the temperature state of the humidity sensor is compensated for.

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