Exhaust gas purifier and system for exhaust gas purification

Abstract

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.

Description

technical field [0001] The present invention relates to an exhaust gas purification device and an exhaust gas purification system capable of constituting a compact and low-cost purification device equipped with a selective reduction NOx catalyst and a DPF (Diesel Particulate Filter: Diesel Particulate Filter) ), the exhaust gas purification system that performs urea water injection and direct fuel injection in the exhaust pipe. Background technique [0002] In internal combustion engines mounted on automobiles, it is important to reduce NOx (nitrogen oxides) and PM (particulate matter) in exhaust gases. As one of exhaust gas purification methods for reducing this NOx, there is an exhaust gas purification method using a selective reduction NOx catalyst (SCR catalyst), which sprays an ammonia-based solution such as urea into the exhaust pipe, and generates ammonia by hydrolysis , and then selectively reduce NOx on adsorption materials such as zeolite. [0003] This SCR (Sele...

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Problems solved by technology

[0013] However, in this engine exhaust gas purification device, since HC such as fuel is not directly injected into the exhaust pipe but post-injected, part of the fuel during the post-injection falls into the oil from the cylinder liner, and there is a possibility that the lubricating oil is diluted by the fuel. A lubricating oil dilution problem

In addition, since post-injection is used, there is a problem that it cannot be used as a reference when compacting the exhaust gas purification system in the case of both urea supply and HC supply that directly inject HC into the exhaust pipe.

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