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Method of controlling an engine exhaust gas system and method of detecting deterioration of catalyst/adsorbing means

  • US 6,026,640 A
  • Filed: 05/17/1999
  • Issued: 02/22/2000
  • Est. Priority Date: 06/21/1996
  • Status: Expired due to Term
First Claim
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1. A method of controlling an exhaust gas system of an internal combustion engine which operates mainly under a lean condition, which system comprises a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst;

  • said method comprising the steps of;

    (a) switching temporarily the operation condition of said internal combustion engine into a stoichiometric condition or a rich condition so that the nitrogen oxide adsorbed to said nitrogen oxide reducing catalyst is detached or decomposed when an output of the nitrogen oxide sensor reaches a predetermined level,(b) returning the operational condition back to a lean condition when an electromotive force, or a pumping current of a first pumping cell, of the nitrogen oxide sensor reaches a predetermined level.

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