Reducing agent dosage amount control method for selective catalytic reduction system of e.g. petrol engine for motor car, involves outputting reference of increased risk of release of ammonia to control unit of catalytic reduction catalyst

摘要

The method involves calculating maximum ammonia load (mNH3LdMax) of a selective catalytic reduction (SCR) catalyst. A threshold ammonia load of the catalyst is calculated by multiplying metering amount of ammonia by a factor and/by addition of an offset, and subtracting consumption of ammonia of the catalyst. Reference of increased risk of release of ammonia is output to a control unit of the SCR system until the threshold ammonia load is greater than or equal to maximum ammonia load, for disabling dosing amount of a reducing agent. Independent claims are also included for the following: (1) a computer program product for controlling dosage amount of a reducing agent in SCR system (2) a SCR system.