scr treatment of engine exhaust using temperature control

Abstract

The exhaust system of the internal combustion engine is periodically dosed to replenish the SCR catalyst with ammonia. If dosing is scheduled and the exhaust gas temperature is too low to ensure replenishment, a forced increase in the exhaust gas temperature for the dosing period is carried out. At the same time, a diagnostic for confirming correct operation of the catalytic converter can advantageously be run.

Description

technical field [0001] The present invention relates to the treatment of exhaust emissions from internal combustion engines, and in particular to engine exhaust systems incorporating selective catalytic reduction. Aspects of the invention relate to a method, an engine and a vehicle. Background technique [0002] Legislation requires the treatment of harmful emissions from internal combustion engines. Selective Catalytic Reduction (SCR) uses ammonia as a reducing agent to convert nitrogen oxides (NOx) to nitrogen and water. Urea is typically injected periodically into the engine exhaust system upstream of the SCR chamber, where it mixes with the hot exhaust to produce ammonia. This ammonia is absorbed onto the SCR catalyst in the chamber and effectively treats NOx. Over time, the ammonia is consumed, so further injections of urea are required to replenish the catalyst. Ammonia consumption is typically estimated in an engine management system by monitoring engine activity ...

AI Technical Summary

Problems solved by technology

This inhibition avoids the formation of solid deposits in the chamber and the waste of urea, but unavoidable prolonged city driving may eventually lead to complete depletion of the catalyst

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