Exhaust gas purifying apparatus

Abstract

This invention provides an exhaust gas purifying apparatus which can be mounted well on a vehicle without causing relative twisting between a particulate filter and a selective reduction catalyst. The exhaust gas purifying apparatus includes a communication flow passage having an S-shaped structure. In this communication flow passage, the particulate filter and the selective reduction catalyst are held with a casing and are disposed in parallel so that the inlet side end of the particulate filter and the inlet side end of the selective reduction catalyst face the same direction. The S-shaped structure is constructed so that an exhaust gas discharged from an outlet end of the particulate filter is returned in an opposite direction and is introduced into the inlet side end of the adjacent selective reduction catalyst, and so that urea water can be added by urea water adding means provided in an intermediate position of the communication flow passage. The casing for the particulate filter and the selective reduction catalyst is integrally constrained by a plate of a rigid body (a constraining member).

Description

technical field [0001] The present invention relates to an exhaust purification device. Background technique [0002] In recent years, it has been proposed that a particulate filter for trapping particles in the exhaust gas is provided in the middle of the exhaust pipe, and that a selective reduction catalyst is provided downstream of the particulate filter. can also make NO x It selectively reacts with ammonia, and urea water as a reducing agent is added between the selective reduction catalyst and the particulate filter to achieve simultaneous reduction of particulates and NOx. [0003] In this case, since the addition of urea water to the selective reduction catalyst is performed between the particulate filter and the selective reduction catalyst, if it is desired to ensure that the added urea water in the exhaust gas is thermally decomposed into ammonia and carbon dioxide If there is sufficient reaction time, it is necessary to prolong the distance from the addition po...

AI Technical Summary

Problems solved by technology

[0003] In this case, since the addition of urea water to the selective reduction catalyst is performed between the particulate filter and the selective reduction catalyst, if it is desired to ensure that the added urea water in the exhaust gas is thermally decomposed into ammonia and carbon dioxide If there is sufficient reaction time, it is necessary to prolong the distance from the addition position of urea water to the selective reduction catalyst. However, if the particulate filter and the selective reduction catalyst are separated by a sufficient distance, it will significantly damage the Mountability to the vehicle deployment

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