Method and system for an exhaust catalyst

Abstract

The invention relates to a method and a system for an exhaust catalyst. Methods and systems are provided for operating an engine exhaust aftertreatment system to increase the efficiency of an exhaustunderbody catalyst and reduce engine emissions. In one example, a bypass passage may be coupled to a main exhaust passage and during conditions which may adversely affect functionality of the underbody catalyst, exhaust may be opportunistically routed via the bypass passage avoiding the underbody catalyst. Exhaust heat may be recovered via a heat exchanger coupled to the bypass passage, and the heat may be used for engine heating, and passenger cabin heating.

Description

technical field [0001] The present description generally relates to methods and systems for controlling a vehicle engine to increase the efficiency of an exhaust aftertreatment system and reduce engine emissions. Background technique [0002] An emission control device, such as an underbody catalyst, coupled to the exhaust passage of an internal combustion engine, reduces combustion byproducts such as nitrogen oxides, carbon monoxide, and hydrocarbons. Engine cold-start emissions generated prior to light-off of the underbody catalyst can contribute a significant proportion to total exhaust emissions. The efficiency of the underbody catalyst may be affected by exhaust temperature and may be suboptimal outside of a certain temperature range. Furthermore, catalyst functionality may be adversely affected by oxygen loading in the catalyst above a threshold. [0003] Accordingly, various methods have been developed to selectively route exhaust gas through exhaust catalysts based...

AI Technical Summary

Problems solved by technology

Oxygen saturation may cause the catalyst to convert NO adsorbed on the catalyst x The reduction of the capacity, thereby affecting the emission quality

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