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Air-fuel ratio control system

  • US 4,913,122 A
  • Filed: 01/11/1988
  • Issued: 04/03/1990
  • Est. Priority Date: 01/14/1987
  • Status: Expired due to Term
First Claim
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1. An air-fuel ratio control system for an engine, comprising:

  • means for detecting air-fuel ratio of air-fuel mixture to be inducted to the engine;

    means for detecting operating condition of the engine;

    means for calculating an air-fuel ratio correction coefficient in accordance with said detected air-fuel ratio;

    means for accomplishing feedback control of the air-fuel ratio into a stoichiometric value in accordance with said air-fuel ratio correction coefficient;

    means for forming a plurality of learning areas defined respectively by engine operating conditions, learning being able to be made in each learning area, at least a part of each learning area being under said feedback control and at least one of said learning areas having a part which is never under feedback control;

    means for calculating a learning coefficient for said learning area corresponding to said detected engine operating condition, in accordance with said air-fuel ratio correction coefficient under said feedback control, said learning coefficient being memorized in said at least a part of each learning area; and

    means for accomplishing feedforward control of the air-fuel ratio into a lean value which is leaner than said stoichiometric value, in accordance with said learning coefficient.

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