Patent ID: 6600998
Filing Date: 2003-07-29
Classification: F01N,F02D,Y02T

Abstract:
A catalyst deteriorating state detecting apparatus for detecting a deteriorating state of a catalyst provided in an exhaust-gas path from an internal combustion engine, comprising:an upstream sensor that detects an air-fuel ratio or exhaust gas concentration flowing through the exhaust-gas path, said upstream sensor being positioned upstream of the catalyst; a downstream sensor that detects an air-fuel ratio or exhaust gas concentration, said downstream sensor being positioned downstream of said catalyst; a storage amount computing device that calculates a storage quantity of the catalyst based on a flow rate of the exhaust gas flowing into the catalyst during a change in output generated by a downstream sensor due to a variation in a target air-fuel ratio; and a deteriorating state determining device that determines whether a deteriorating state of the catalyst exists based on the storage quantity calculated by the storage amount computing device.