Method for use in conjunction with an exhaust-gas aftertreatment system

摘要

A method for an exhaust-gas aftertreatment system which is operated on an internal combustion engine operated with an excess of air, in which exhaust-gas aftertreatment system soot particles are separated out of exhaust gas by a particle filter and the particle filter is regenerated with the aid of NO2 formed on an NO oxidation catalytic converter mounted upstream of the particle filter. A reduction of the nitrogen oxides is realized by a reducing agent which splits to form ammonia being metered into the exhaust-gas flow upstream of the particle filter and the particle filter is laden with a catalytically active material for the selective catalytic reduction of nitrogen oxides. The NH3 to NOx ratio (feed ratio α) is varied in phases by changing the nitrogen oxide untreated emissions and/or the supplied amount of reducing agent, in such a way that the feed ratio α alternates in phases between values of greater than one and values of less than one.

主权项

1. A method for an exhaust-gas aftertreatment system that operates on exhaust gas of an internal combustion engine operated with an excess of air, the method comprising:
separating, by a particle filter, soot particles out of the exhaust gas; regenerating the particle filter with the aid of NO2 formed on an NO oxidation catalytic converter mounted upstream of the particle filter; reducing nitrogen oxides by metering a reducing agent, which splits to form ammonia, into an exhaust-gas flow upstream of the particle filter, wherein the particle filter is laden with a catalytically active material for selective catalytic reduction of nitrogen oxides; periodically varying an NH3 to NOx ratio (feed ratio α) in phases by changing at least one of the nitrogen oxide (NOx) untreated emissions and the metered amount of reducing agent, in such a way that the feed ratio α periodically alternates in phases between values of greater than one and values of less than one.