Patent ID: 6367245
Filing Date: 2002-04-09
Classification: F01N,Y02T

Abstract:
A method of evaluating a deteriorated state of an exhaust gas adsorbent disposed in an exhaust passage supplied with an exhaust gas emitted from an internal combustion engine, said exhaust gas adsorbent being operable alternatively in an adsorption mode for adsorbing a particular component of the exhaust gas and a desorption mode for desorbing the adsorbed component depending on an environmental condition at the time said exhaust gas is supplied to the exhaust passage, comprising the steps of:providing a first exhaust gas sensor and a second exhaust gas sensor for generating respective outputs depending on the concentration of said particular component, respectively upstream and downstream of said exhaust gas adsorbent; adsorbing said particular component with said exhaust gas adsorbent in said adsorption mode while supplying the exhaust gas from said internal combustion engine to said exhaust passage; calculating an amount of said particular component which has been adsorbed by said exhaust gas adsorbent per unit time, based on the difference between the outputs of said first and second exhaust gas sensors which is obtained while said particular component is being adsorbed by said exhaust gas adsorbent; evaluating a deteriorated state of said exhaust gas adsorbent using the calculated adsorbed amount of said particular component; and wherein said step of calculating the adsorbed amount of said particular component comprises the step of converting the difference between the outputs of said first and second exhaust gas sensors depending on a flow rate of the exhaust gas flowing in said exhaust passage when the outputs of said first and second exhaust gas sensors are obtained, and a temperature of said exhaust gas, for thereby determining the adsorbed amount of said particular component.