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Apparatus for monitoring leakage into exhaust lines

  • US 5,351,526 A
  • Filed: 06/11/1993
  • Issued: 10/04/1994
  • Est. Priority Date: 06/13/1992
  • Status: Expired due to Fees
First Claim
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1. A monitoring apparatus for an internal combustion engine having an exhaust gas path and arranged to intercept a air/fuel mixture fed to the engine while operating, including intermittent reduced pressure phases of engine operation in which the exhaust gas path undergoes periods of reduced pressure relative to the atmospheric pressure of external air, and including a first lambda probe located in the exhaust gas path for sensing an oxygen concentration in the exhaust gas and for issuing a first signal indicative of the oxygen concentration, and a control device responsive to the first signal from the first lambda probe for controlling engine operation by controlling the ratio of the air/fuel mixture fed to the engine, the improvement comprising:

  • a second lambda probe for sensing the oxygen concentration in the exhaust gas and for issuing a second signal indicative of the oxygen concentration, said second lambda probe being located in the exhaust gas path at a point spaced therealong from the first lambda probe, said control device being arranged such that it is also responsive to said second signal from said second probe, said control device including means for detecting a deviation of the first signal from the first lambda probe from that of said second signal from said second lambda probe by effecting a comparison measurement of the first signal and said second signal from said first and second lambda probes, respectively, during reduced pressure phases in the engine operation and means for generating an error signal when said deviation arises on the basis of an increase in the oxygen concentration during said reduced pressure phases, said increase in oxygen concentration being indicative of external air suction leakage into the exhaust gas path.

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