Exhaust gas cleaning device

摘要

An exhaust cleaning device includes a NOx storage reduction catalyst storing NOx when an air-fuel ratio of an inflowing exhaust gas is lean and releasing the stored NOx when the air-fuel ratio of the inflowing exhaust gas is rich; an air-fuel ratio changing unit; a reducing agent supplying unit which adds a reducing agent to the NOx storage reduction catalyst; a temperature detection unit which detects a temperature of the NOx storage reduction catalyst; a poisoning recovery timing judging unit which judges a timing for executing a SOx poisoning recovery process of releasing SOx from the NOx storage reduction catalyst; and a control unit.