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Engine with dual sensor closed loop fuel control

  • US 3,939,654 A
  • Filed: 02/11/1975
  • Issued: 02/24/1976
  • Est. Priority Date: 02/11/1975
  • Status: Expired due to Term
First Claim
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1. For use with an internal combustion engine including means for supplying air and fuel thereto in variable ratio and exhaust means including a catalytic converter effective, when supplied with exhaust gases containing air and fuel in a certain ratio, to accelerate simultaneously the oxidation of unburned fuel and the reduction of nitrogen oxides and characterized by time delay effects when the content of the gas introduced therein is varied, apparatus for controlling the ratio of air and fuel in said exhaust system to said certain ratio, said apparatus comprising:

  • means for generating a first signal indicative of the air-fuel ratio within said exhaust means upstream from said catalytic converter, said first signal generating means being characterized by time-related drift in closed cycle control operation;

    means for generating a second signal indicative of the air-fuel ratio within said exhaust means downstream from said catalytic converter, said second signal generating means being characterized by catalytic converter-related, time-delayed response in relation to said first signal generating means; and

    means for continually adjusting said fuel and air supply means to vary the ratio of fuel and air supplied to said engine in response to the direction of the deviation of said first signal from the time integral of the extent the second signal deviates from a fixed reference, said adjustment being in sense to reduce the deviation of the ratio of fuel and air in the exhaust means from said certain ratio.

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