| 摘要 |
The invention relates to a method for desulphatizing an NOx accumulator or an NOx accumulator catalytic converter installed downstream in an internal combustion engine operated with a lean mixture, wherein the internal combustion engine is operated in several rich-lean mixture cycles after a predetermined desulphatization temperature has been set. In the rich mixture cycles, the lambda value drops to less than 0.985, whereby values in the range of approximately 0.95 are preferred, since the emission of accumulated sulfur in the form of sulfur dioxide is ostensibly accelerated. Undesired hydrogen sulfide formation arising as a result of the annoyance caused by bad smell is delayed and occurs at a clearly slower rate. The duration of reduction is so short that traceable emissions of hydrogen sulfide can no longer be detected while practically total desulphatization of the NOx accumulator catalytic converter is ensured by operation in cycles. The rich-lean mixture phases of the cycles last approximately 2-10 s or 2-6 s so that ostensibly shorter regeneration times with higher lambda values are obtained in comparison with conventional methods while at the same time consumption is correspondingly reduced.
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