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Apparatus and method for detecting misfiring in an internal combustion engine

  • US 5,351,528 A
  • Filed: 04/21/1993
  • Issued: 10/04/1994
  • Est. Priority Date: 08/13/1990
  • Status: Expired due to Term
First Claim
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1. A misfiring detecting apparatus for an internal combustion engine, comprising:

  • a pressure sensor for sensing the pressure in a cylinder of the engine and for generating a corresponding output signal;

    a differentiator for differentiating the output signal of said pressure sensor and for generating a corresponding output signal;

    a signal processor for processing the output signal of said differentiator to generate a power stroke pressure information signal;

    a threshold calculator for calculating a threshold for a misfiring determination based on operating conditions of the engine, wherein said threshold calculator includes means for generating a first threshold having a first prescribed value which is predetermined based on the engine operating conditions and stored in a memory when said engine has a first running condition, and for generating a second threshold having a second prescribed value which is predetermined based on the engine operating conditions and stored in said memory when said engine has a second running condition;

    a comparator for comparing the power stroke pressure information signal from said signal processor with the threshold from said threshold calculator; and

    a misfiring determiner for determining, based on a result of the comparison made by said comparator, whether misfiring took place in the cylinder of the engine.

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