EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

In order to more precisely estimate the amount of reducing agent adsorbed by a selective reduction NOx catalyst while maintaining the selective reduction NOx catalyst in a state wherein NOx can be purified, the device is equipped with: an upper limit value calculation unit, which calculates an upper limit value for the amount of the reducing agent adsorbed by the selective reduction NOx catalyst when the internal combustion engine is operating steadily and the reducing agent is being supplied continuously; and an estimation unit, which estimates that the upper limit value, as calculated by the upper limit calculation unit when the internal combustion engine is operating steadily and the reducing agent has been supplied for more than a prescribed time, is the amount of reducing agent that has been adsorbed by the selective reduction NOx catalyst at that time.