Daimler Chrysler Ag

Conti Temic Microelectronic Gmbh

Holger Leye

Aleksandar Knezevic

Carsten Plog

Ralf Moos

Dirk Voigtlaender

Thomas Birkhofer

Eckard Irion

Mirko Smuk

Thomas Ried

In a method for identifying the state of an NOx storage catalyst which is cyclically loaded with NOx in the exhaust stream of an internal combustion engine and regenerated, two electrical defining quantities, independent of each other, of the electrically complex impedance of the NOx storage catalyst are detected, one of the two electrical quantities being a measure of the degree of loading of the NOx storage catalyst, and from the second electrical quantity the point in time being identifiable for the end of the regeneration process of the NOx storage catalyst.

Method for identifying the state of an NOx storage catalyst

A method for determining the reducing agent concentration (NH ) in the exhaust-gas flow of an internal combustion engine, using a zeolitic NH gas sensor that supplies a base measuring value, which is initially corrected by an offset value and a correction value that depends on the H O concentration of the exhaust gas to form an intermediate value. The intermediate value is subsequently corrected by an additional value that depends on the NO and NH concentration of the exhaust gas. In particular at or above the limits for the operating range, the accuracy of the method increases for one of the following conditions: gas compositions with NO concentrations >500 ppm, extremely low NH concentrations <20 ppm or high NH concentrations >100 ppm.

Method for determining the reducing agent concentration (NH3) in the exhaust-gas flow of an internal combustion engine

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Unterensingen, Germany

Holger Leye