Exhaust gas purification device for internal combustion engine

摘要

An exhaust gas purification device, which purifies exhaust gas in first and second exhaust gas passages (20A, 20B) extending from an internal combustion engine, is equipped with: a convergence passage (22) extending from the area of convergence of the first and second exhaust gas passages; a first sub NOx catalyst (25A) provided in the first exhaust gas passage; a second sub NOx catalyst (25B) provided in the second exhaust gas passage; a main NOx catalyst (26) provided in the convergence passage; a first addition unit (30A) that adds an ammonia source with a first additive amount upstream from the first sub NOx catalyst so as to supply urea water to the first sub NOx catalyst; and a second addition unit (30B) that adds an ammonia source with a second additive amount upstream from the second sub NOx catalyst so as to supply urea water to the second sub NOx catalyst.