초록 ▼

A method is provided for the catalytic conversion of nitrogen oxides contained in the exhaust gas of an internal combustion engine. A reducing agent is added in a controlled manner upstream of a denitrification catalyst, as seen in exhaust gas flow direction, and in dependence on a nitrogen oxide co

A method is provided for the catalytic conversion of nitrogen oxides contained in the exhaust gas of an internal combustion engine. A reducing agent is added in a controlled manner upstream of a denitrification catalyst, as seen in exhaust gas flow direction, and in dependence on a nitrogen oxide concentration. The reducing agent is added in a superstoichiometric amount in relation to the nitrogen oxide content if an operating parameter and/or a value derived from the operating parameter falls below or exceeds a threshold value. The addition of the reducing agent is then terminated or continued in a substoichiometric manner. The invention provides a measure for obtaining an extremely high average nitrogen oxide conversion, especially under varying operating conditions of the internal combustion engine.

대표청구항 ▼

1. In a method for the catalytic conversion of nitrogen oxides contained in the exhaust gas of an internal combustion engine, by adding a reducing agent to the exhaust gas upstream of a denitrification catalytic converter, as seen in exhaust gas flow direction, and metering the reducing agent as a f

1. In a method for the catalytic conversion of nitrogen oxides contained in the exhaust gas of an internal combustion engine, by adding a reducing agent to the exhaust gas upstream of a denitrification catalytic converter, as seen in exhaust gas flow direction, and metering the reducing agent as a function of a nitrogen oxide concentration, the improvement which comprises:a) measuring an operating parameter of the internal combustion engine influencing the metering; assigning a limit value to the operating parameter; establishing an operating state of the internal combustion engine being unfavorable for metering, upon falling below or exceeding the limit value; b) increasing a metered quantity of reducing agent in a preset manner at least one of before and during falling below or exceeding the limit value; and c) terminating the increase in the metered quantity during the unfavorable operating state.