Ammonia storage control

Abstract

Various methods for controlling ammonia levels stored in a catalyst by controlling exhaust gas temperatures are provided. In one embodiment, a temperature of a catalyst in an internal combustion engine is determined. If the temperature of the catalyst exceeds a first threshold at which an ammonia capacity of the catalyst for the temperature is below a current stored ammonia level in the catalyst, a load of the engine is reduced including adjusting a torque output of a motor operatively coupled to the engine.

Description

[0001] Cross References to Related Applications [0002] This application claims priority from German Patent Application No. 102012212051.3 filed on July 11, 2012, the entire content of which is hereby incorporated by reference for all purposes. technical field [0003] The present invention relates to a method of controlling the level of ammonia stored in a catalyst of an internal combustion engine (ICE). Background technique [0004] Internal combustion engines may include one or more catalysts configured to reduce the level of emissions produced during the combustion of fuel. For example, selective catalytic reduction (SCR) catalysts can be used to reduce the levels of nitrogen oxides (NOx) emitted after fuel combustion. SCR catalysts may use one or more reducing agents to enhance NOx conversion, such as ammonia. For a given temperature, the SCR catalyst has a storage capacity that determines the level of reductant that can be stored in the catalyst. Exhaust temperatur...

AI Technical Summary

Problems solved by technology

Ammonia slip in turn leads to increased NOx emissions to the surrounding environment

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