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System and method for estimating tailpipe a emissions in a vehicle

  • US 5,916,294 A
  • Filed: 07/31/1997
  • Issued: 06/29/1999
  • Est. Priority Date: 07/31/1997
  • Status: Expired due to Fees
First Claim
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1. A method for estimating tailpipe emissions in a vehicle with a catalytic converter coupled to an engine exhausting a combusted gas stream comprised of hydrocarbon gas and other combustible gasses to the catalytic converter, the catalytic converter exhausting a catalyzed gas stream dependent thereon, the method comprising steps of:

  • sensing the catalyzed gas stream and providing a total-combustible gas signal dependent thereon, the total-combustible gas signal having a magnitude comprised of a first portion, dependent on a concentration of the hydrocarbon gas in the catalyzed gas stream, and a second portion, dependent on a concentration of the other combustible gasses in the catalyzed gas stream, where a magnitude relationship between the first portion and the second portion is variable when the catalyzed gas stream transitions into a region on the rich side of stoichiometry; and

    filtering the total-combustible gas signal and providing a filtered total-combustible gas signal dependent thereon, the filtered total-combustible gas signal having a magnitude comprised of a first portion, dependent on the first portion of the total-combustible gas signal, and a second portion, dependent on the second portion of the total-combustible gas signal, wherein a magnitude relationship between the first portion and the second portion of the filtered total-combustible gas signal is substantially constant when the catalyzed gas stream transitions into the region on the rich side of stoichiometry.

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