Method for monitoring catalyst in exhaust gas purification system of internal combustion engine, involves determining oxygen storage capability of catalyst and varying air-fuel ratio based on exhaust gas mass flow rate

摘要

The method involves arranging a primary exhaust gas probe at front surface of a catalytic converter. A secondary exhaust gas probe is arranged behind the catalytic converter. The oxygen storage capability of catalyst is determined and evaluated during a pre-conditioning phase (11) and a measuring phase (13). The oxygen storage capability of catalyst from an integrated oxygen entry portion (15) is determined during measuring phase based on air-fuel ratio (14) detected by secondary exhaust gas probe. The air-fuel ratio is varied based on exhaust gas mass flow rate. An independent claim is included for a device for monitoring catalyst in exhaust gas purification system of internal combustion engine.