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Apparatus for controlling engine operable on gasoline/alcohol fuel blend

  • US 4,957,087 A
  • Filed: 10/11/1989
  • Issued: 09/18/1990
  • Est. Priority Date: 10/11/1988
  • Status: Expired due to Term
First Claim
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1. An apparatus for use with an internal combustion engine operable on either of gasoline fuel and gasoline/alcohol fuel blend, comprising:

  • an alcohol concentration sensor sensitive to an alcohol concentration of the fuel to be delivered to the engine for producing an alcohol concentration signal indicative of a sensed alcohol concentration;

    an oxygen sensor sensitive to an oxygen content of exhaust gases discharged from the engine for producing an air/fuel ratio feedback signal; and

    a control unit coupled to the alcohol concentration sensor and the oxygen sensor for controlling the amount of fuel metered to the engine and the timing of ignition at the engine, the control unit including means responsive to the air/fuel ratio feedback signal for calculating a difference of the air/fuel ratio from a stoichiometric value, first means for calculating a first value for the amount of fuel metered to the engine based on engine operating conditions, second means for calculating a second value for the ignition timing based on engine operating conditions for the sensed alcohol concentration, third means for correcting the calculated first value for the sensed alcohol concentration, fourth means for correcting the calculating first value to provide fuel enrichment during high engine load conditions, fifth means for correcting the calculated first value based on the calculated air/fuel ratio difference to provide a closed loop air/fuel ratio control, sixth means responsive to failure in the alcohol concentration sensor for producing a failure signal, and seventh means responsive to the failure signal for forcing the third means to correct the calculated first value for a predetermined alcohol concentration, the seventh means inhibiting the fourth means from providing fuel enrichment while forcing the second means to calculate the second value for the gasoline fuel when the closed loop air/fuel ratio control is clamped after the third means is forced to correct the calculated first value for the predetermined alcohol concentration, the seventh means forcing the fourth means to correct the calculated first value based on the calculated air/fuel ratio difference and the second means to calculate the second value based on the calculated air/fuel ratio difference when the closed loop air/fuel ratio control is in order after the third means is forced to correct the calculated first value for the predetermined alcohol concentration.

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