METHOD FOR PREDICTING HYDROCARBON CONCENTRATION CHANGE AND APPARATUS FOR DIAGNOSING DEGRADATION OF HYDROCARBON ADSORPTION CATALYST

摘要

PROBLEM TO BE SOLVED: To provide a method for accurately predicting an HC (hydrocarbon) concentration change and to provide an apparatus for accurately diagnosing a degradation of a hydrocarbon adsorption catalyst.;SOLUTION: The method for predicting the hydrocarbon concentration change includes the steps of adsorbing the hydrocarbon in a predetermined temperature range, and predicting the hydrocarbon concentration change at a downstream side from the catalyst in an exhaust gas passage having the catalyst for discharging the adsorbed hydrocarbon with a temperature rise for cleaning. The method further includes a detecting step of detecting the temperature of the catalyst, a first predicting step of predicting the concentration in the exhaust gas at a first period and an amount of the hydrocarbon adsorbed to the catalyst by using the concentration in the gas at an upstream side from the catalyst based on a hydrocarbon adsorbing speed R1, a hydrocarbon discharging speed R2 and a cleaning model for removing the hydrocarbon by the catalyst, and a second predicting step of predicting the concentration in the exhaust gas in a predetermined period by sequentially conducting predicting of the concentration and the amount of the hydrocarbon in the gas at a second period after the first period similarly to the first step by using the concentration and the amount of the hydrocarbon at the predicted first period.;COPYRIGHT: (C)2004,JPO