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System and method for filtering a misfire detecting data stream to yield optimum measurement of misfire rate

  • US 5,305,635 A
  • Filed: 04/02/1993
  • Issued: 04/26/1994
  • Est. Priority Date: 04/02/1993
  • Status: Expired due to Fees
First Claim
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1. A misfire detection system for measuring whether a multiple cylinder combustion engine is misfiring beyond acceptable threshold levels, comprising:

  • sensing means, coupled to the engine, for measuring firings of each cylinder of the multiple cylinder engine during operation of the engine;

    misfire detector means, coupled to said sensing means, for processing the signals received from said sensing means, for producing a current misfire detection data stream of first and second logic signals, wherein said first logic signals indicate a current misfire condition and said second logic signals indicate a current normal firing of the engine;

    geometric filter means, coupled to said misfire detector means, for receiving said current misfire detection data stream, for combining said current misfire detection data stream with previously detected and stored measured data representing an engine misfire rate and for replacing the previously stored measured data by said combined current and previously stored data to produce a misfire rate output measurement;

    storage means for storing threshold values;

    comparator means, coupled to said geometric filter means and to said storage means, for comparing said combined current and previously stored data and said stored threshold values and for generating an actuation signal if said combined current and previously stored data exceed said stored threshold values; and

    a diagnostic indicator, coupled to said comparator means, for indicating a misfire condition in the engine upon receiving said actuation signal produced by said comparator.

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