INTERNAL COMBUSTION ENGINE EXHAUST AIR PURIFICATION DEVICE

摘要

An NOx selection reduction catalyst (15) is arranged in an exhaust air channel of an internal combustion engine and an adhesion amount of HC attached to the NOx selection reduction catalyst (15) is estimated. When the estimated HC adhesion amount exceeds a predetermined allowance amount, the temperature of the NOx selection reduction catalyst (15) is increased so as to detach the HC from the NOx selection reduction catalyst (15). Thus, it is possible to recover HC poisoning of the NOx selection reduction catalyst (15).