Addition-amount controller for exhaust gas purifying agent and exhaust emission control system

摘要

In an addition-amount controller for an exhaust gas purifying agent to be used for an exhaust emission control system, a catalyst has properties of storing NH3 and further decreasing the critical reaction temperature as an amount of NH3 storage at the catalyst is increased. In the addition-amount controller, a present NH3 storage amount that is a storage amount of NH3 of the catalyst is detected at a detection time, the NH3 storage amount of the catalyst is changed by controlling an addition amount by an addition valve, and the NH3 storage amount of the catalyst is controlled to a target NH3 storage amount based on the detected present NH3 storage amount.