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Emission control system for internal combustion engines utilizing balance differential amplifier stage

  • US 4,171,690 A
  • Filed: 03/07/1977
  • Issued: 10/23/1979
  • Est. Priority Date: 03/08/1976
  • Status: Expired due to Term
First Claim
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1. An emission control system for an internal combustion engine having an air-fuel mixing and proportioning device for delivery of proportioned air-fuel mixture to the cylinder of said engine in accordance with a low level noise and long term drift compensated error correction signal, comprising:

  • an exhaust composition sensor for sensing the concentration of an exhaust composition of the emissions from said engine to generate a first signal representative of the sensed concentration;

    means for generating said compensated error correction signal; and

    means for controlling the air-fuel mixing and proportioning device in response to said compensated error correction signal;

    said compensated error correction signal generating means comprising;

    (a) means for generating a second signal substantially representative of a mean value of said first signal;

    (b) means for generating a third signal representative of the difference in amplitude between said first and second signals;

    (c) means for combining said third signal with a predetermined DC voltage having a level higher than noise so that said third signal fluctuates above and below said DC voltage; and

    (d) means for modifying the amplitude of said combined signal in accordance with a predetermined control characteristic to generate said compensated error correction signal.

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