Siemens Aktiengesellschaft

Corinna Pfleger

Hong Zhang

Wolfgang Ludwig

J&uuml;rgen R&ouml;ssler

Juergen Roessler

Method for the testing of the exhaust gas recirculation system of an internal combustion engine that returns exhaust gas at an exhaust gas recirculation rate from the exhaust line to the intake line, in which a specific adjustment of the exhaust gas recirculation rate is set, the NOx concentration in the exhaust gas is measured and in the absence of a differential concentration varying as a function of the adjustment of the exhaust gas recirculation rate, a defect of the exhaust gas recirculation system is diagnosed.

Method for the testing of an exhaust gas recirculation system

A method is provided for checking the dynamic behavior of a measuring sensor which detects a substance concentration in the exhaust tract of an internal combustion engine operating with excess air, downstream of an NOx storage catalytic converter. A signal from the measuring sensor is monitored during a regeneration phase. When a predetermined signal profile is absent, a faulty dynamic behavior is diagnosed.

Method for checking the dynamic behavior of a measuring sensor in the exhaust tract of an internal combustion engine

Values for a raw NOx concentration of an internal combustion engine, that are stored on an operating point basis, are read out from a characteristic map and an adaptation of variations in concentration takes place on the basis of an output signal of an NOx sensor provided downstream of a NOx storage catalyst, either by modification of a reduction factor, which serves for the calculation of a corrected raw NOx concentration from the raw NOx concentration, or by direct correction of the values read out from the characteristic map for the raw NOx concentration with a raw concentration correction factor.

Method for adapting a raw NOx concentration value of an internal combustion engine operating with an excess of air

In a method for regenerating a NOx storage catalytic converter disposed in an engine exhaust operating with air excess, in operating ranges, the improvement includes storing NOx in the exhaust gas in the converter in a storage phase and catalytically converting the stored NOx in a regeneration phase. The signal of the NOx sensor disposed downstream of the converter is detected in the operating range of the overrun fuel cut-off and an average/minimum value is formed from the individual measured values. The average/minimum value is stored as an offset value of the sensor signal. In operating ranges beyond the engine overrun fuel cut-off, the signal of the NOx sensor is detected and the offset value is taken into account when the signal is processed further, in that the offset-corrected signal is compared with a threshold value. In the event that the threshold value is exceeded, a regeneration phase of the converter is initiated.

Method for regenerating a NOx storage catalytic converter for an internal combustion engine

The present invention includes a method and apparatus for cleaning exhaust of an internal combustion engine. The internal combustion engine has a catalyst and a lambda probe disposed in an exhaust gas tract. The lambda probe is disposed upstream from the catalyst, and is capable of an output &lgr;o substantially close to lambda&equals;1. The present invention includes determining a relationship between a downstream NOx concentration and a lambda value such that a lambda value substantially greater than 1 indicates a substantially greatly increased NOx concentration, and determining a relationship between a downstream NH,concentration and a lambda value such that a lambda value substantially less than 1 indicates a substantially greatly increased NH,concentration.

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Donaustauf, Germany

Corinna Pfleger