One of the most promising schemes for meeting the 1981 emission standards for hydrocarbon, carbon monoxide and nitrogen oxides emissions employs a 3-way catalyst in conjunction with a clased-loop engine-control system. The problems involved in this approach and the engineering designs to resolve these problems are discussed in this paper. The operation of this system is explained, and the elements of the closed-loop system are illustrated. The maintenance of the exhaust constituents at the precise value at which the 3-way catalyst is most effective is the purpose of the closed-loop system. Components of the system include an exhaust gas sensor, an electronic control unit, and a carburetor. Tighter emission standards may require a more sophisticated way to schedule air-fuel ratio during the cold-start open-loop operation. Other features can also be added to the control logic to improve driveability or emissions performance. It is noted that although an analog control unit may represent the lowest cost implementation, in the long run, a microprocessor will offer flexiblity to incorporate additional engine-control functions.

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    Institute of Electrical and Electronics Engineers (IEEE)

    3 Park Avenue, 17th Floor
    New York, NY  United States  10016-5997
  • Authors:
    • Niepoth, G W
    • Stonestreet, S P
  • Publication Date: 0

Media Info

  • Features: Figures;
  • Pagination: p. 53-55
  • Serial:
    • IEEE Spectrum
    • Volume: 14
    • Issue Number: 11
    • Publisher: Institute of Electrical and Electronics Engineers (IEEE)
    • ISSN: 0018-9235

Subject/Index Terms

Filing Info

  • Accession Number: 00167610
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 27 1977 12:00AM