Patent ID: 6769417
Filing Date: 2004-08-03
Classification: F01N,F02D,F02M,Y02T

Abstract:
An apparatus for evaluating a deteriorated state of a hydrocarbon adsorbent disposed in an exhaust passage of an internal combustion engine for adsorbing hydrocarbons contained in an exhaust gas emitted from the internal combustion engine, based on the transition characteristics of an output signal of a humidity sensor which is disposed in the exhaust passage downstream of said hydrocarbon adsorbent after the internal combustion engine has started to operate, said apparatus comprising:changing timing detecting means for detecting a changing timing at which a humidity represented by the output signal of the humidity sensor changes to a tendency to monotonously increase from a low humidity to a high humidity based on a comparison between a characteristic quantity of a change in the output signal of the humidity sensor and a preset value, after the internal combustion engine has started to operate; evaluating parameter acquiring means for acquiring data representing a total amount of moisture carried by the exhaust gas to said hydrocarbon adsorbent up to said changing timing after the internal combustion engine has started to operate, as a deterioration evaluating parameter for evaluating the deteriorated state of the hydrocarbon adsorbent; characteristic change detecting means for detecting a characteristic change of said humidity sensor based on the output signal of the humidity sensor under a predetermined condition; and characteristic change compensating means for correcting said preset value to detect said changing timing based on the characteristic change detected by said characteristic change detecting means.