EXHAUST GAS PURIFICATION APPARATUS FOR AN INTERNAL COMBUSTION ENGINE

摘要

There is provided a technique which can reduce the NOx stored in an NOx storage reduction catalyst (3). In case where concentrated reduction is carried out so as to add a reducing agent to the NOx storage reduction catalyst in a concentrated manner when a shift has been made from a state in which reduction of the NOx stored in said NOx storage reduction catalyst is unable to be performed in spite of a request for reduction of the NOx into a state in which reduction of the NOx is able to be performed, the level of concentration upon addition of the reducing agent is changed based on the amount of the NOx stored in the NOx storage reduction catalyst and the temperature of the NOx storage reduction catalyst.