Volkswagen Ag

Axel Lang

Frank Schulze

Jens Dr&uuml;ckhammer

Hermann Hahn

Michael Daetz

Uwe Kammann

Axel Wachtendorf

Harald Loeck

Rudolf Krebs

Jens Drückhammer

Frank Michael Wittig

Axel König

Michael Kröger

A process for detecting a state of a catalyst system installed in an exhaust gas channel of an internal combustion engine of a motor vehicle, through which catalyst system exhaust gas from the internal combustion engine flows so that the exhaust gas can be purified, the process including the steps of: detecting at least one operating parameter of the catalyst system over a predetermined time period, determining a total energy output of the internal combustion engine within the predetermined time period, and calculating a characteristic value (k) based on a ratio of the at least one operating parameter to the total energy output.

Method for detecting the state of a catalytic converter system

The invention relates to a method for monitoring the functioning of an NOx sensor, which is arranged in an exhaust gas channel of an internal combustion engine and is located downstream from an NOx storage catalytic converter. The aim of the invention is to detect the faulty functioning of the NOx sensor in a simple manner in order to be able to take appropriate measures if necessary. To this end, the mass of NOx absorbed by the NOx storage catalytic converter is determined within a diagnostic period using a measurement signal of the NOx sensor. At the same time, an absorbed NOx target mass is calculated using a model for the NOx storage catalytic converter. A ratio of the NOx mass to the NOx target mass is then compared to predetermined limit values to determine the functioning of the NOx sensor. The aim of the invention is alternatively accomplished by measuring a duration time for a complete NOx regeneration of the NOx storage catalytic converter. A specified duration time is also calculated for the NOx regeneration using a model for the NOx storage catalytic converter and using a measured or calculated NOx load state. A ratio of the measured duration time to the specified duration time is then compared to predetermined limit values to determine the functioning of the NOx sensor.

Method for monitoring the functioning of a NOx sensor arranged in an exhaust gas channel of an internal combustion engine

An NO concentration in exhaust gas is measured downstream of an NO storage converter. For determining an operating state, particularly damage to the NO storage converter, when the NO storage converter switches from an absorption mode to a regeneration mode, the values of characteristic features of an NO desorption peak in the time curve of the NOx concentration are ascertained and compared to predetermined test patterns, with a comparison result being formed, from which a converter-state signal that characterizes the operating state of the NO converter is determined.

Method for controlling the regeneration of an NOx storage converter

A method and apparatus is provided for monitoring the operation of a NO storage catalytic converter in the exhaust stream of an internal combustion engine. The NO content of the gas stream upstream and downstream of the catalytic converter is measured and used to determine storage efficiency. This is compared to a threshold value, and if the threshold value is not met a regeneration process is performed. The storage value is measured after regeneration to determine if the catalytic converter is faulty.

Apparatus and method for monitoring NOx storage catalytic converters

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Wolfenbüttel, Germany

Axel Lang