Monitoring storage capability of nitrogen oxides storage catalyst arranged in lean burn IC engine comprises using characteristic value for storage capability of catalyst from nitrogen oxides concentration

摘要

Monitoring the storage capability of a nitrogen oxide (NOx) storage catalyst (16) comprises measuring the NOx concentration in the exhaust gas using a NOx sensor (18) downstream of the catalyst; determining a value which characterizes the storage capability of the catalyst from the measured NOx concentration and/or a parameter derived from it; and extrapolating a characteristic value of the catalyst to at least one time point when the lean operating phase of the engine is stopped or interrupted. An Independent claim is also included for a device for monitoring the storage capability of an NOx storage catalyst (16) arranged in an exhaust gas channel (12) of a lean burn IC engine comprising a control device (22) arranged in the engine control unit (20). Preferred Features: The characteristic value determined at a time point of the lean operating phase is stored and tracked over subsequent lean intervals.