Daimler Ag

Jochen Lahr

Berthold Keppeler

Markus Paule

Anke Traebert

Cyrill Kammer

Nicole Werquet

Axel Zuschlag

Rainer Pauls

A method for processing measured values two nitrogen oxide sensors, one of which is arranged upstream of a nitrogen oxide reduction catalytic converter in the exhaust gas system of a motor vehicle and the other of which is arranged downstream of the nitrogen oxide reduction catalytic converter, involves recording and comparing measured values from the two nitrogen oxide sensors at least approximately at the same time. A sensitivity of the first nitrogen oxide sensor and/or of the second nitrogen oxide sensor is changed depending on the result of the comparison.

Method for processing measured values from a nitrogen oxide sensor

In a method for reducing the emission of nitrogen dioxide in a motor vehicle having an exhaust gas purification system having an SCR catalytic converter with adsorption centers for nitrogen oxides, an exhaust gas enriched with ammonia is supplied to the SCR catalytic converter above an operating temperature. Below the operating temperature, the exhaust gas supplied to the SCR catalytic converter is enriched with a material such that an adsorption of nitrogen oxides is inhibited at corresponding adsorption centers of the SCR catalytic converter. In order to reduce the overall NOemissions below a first, predeterminable amount, an exhaust gas enriched with ammonia is supplied to the SCR catalytic converter and the NOportion of the total NOemissions is reduced below a second, predeterminable amount in that NOis converted with hydrocarbons stored in the SCR catalytic converter.

Method for reducing emission of nitrogen oxide in a motor vehicle having a lean burning internal combustion engine

In a method for determining an NOconcentration and/or a concentration ratio of NOand NO in an exhaust tract of a combustion device, such as an internal combustion engine, an NOx sensor that is sensitive with respect to NOand NO is utilized, which provides a NOx output signal correlating with an NOx concentration representing the sum of the concentrations of NOand NO. In order to determine the NOconcentration and/or the concentration ratio of NOand NO, the NOx output signal of a first NOx sensor, which is arranged upstream of an exhaust gas treatment element arranged in the exhaust tract and having the capability of converting NO to NOand/or converting NOto NO, is compared to the NOx output signal of a second NOx sensor, which is disposed downstream of the exhaust gas treatment element.

Method for determining the nitrogen dioxide concentration in exhaust gases

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Stuttgart, Germany

Jochen Lahr