EXHAUST GAS PURIFIER AND SYSTEM FOR EXHAUST GAS PURIFICATION

摘要

An exhaust gas purifier (10) which includes an NOx catalyst (12) of the selective reduction type and a DPF (14) which have been serially arranged, the purifier being disposed in the exhaust passage (2) of an internal combustion engine.  The purifier (10) further includes a passage for urea supply (16) having a hydrolysis catalyst (15) deposited therein and a passage for HC supply (18) having an oxidation catalyst (17) deposited therein, the passages (16) and (18) being disposed in parallel on the upperstream side of both the NOx catalyst (12) of the selective reduction type and the DPF (14).  The purifier (10) furthermore includes a urea feeder (20) which supplies urea to the passage for urea supply (16) and an HC feeder (21) which supplies HCs to the passage for HC supply (18).  Due to the constitution, the system for exhaust gas purification (1), which employs both the NOx catalyst (12) of the selective reduction type and the DPF (14), reconciles the injection of an ammonia solution with the direct injection of HCs into the exhaust pipe in a compact space.