×

Apparatus and method for diagnosing exhaust recirculation system in internal combustion engine

  • US 5,617,833 A
  • Filed: 12/21/1995
  • Issued: 04/08/1997
  • Est. Priority Date: 12/22/1994
  • Status: Expired due to Fees
First Claim
Patent Images

1. An apparatus for diagnosing an exhaust gas recirculation system having exhaust gas recirculation control valve means interposed in an exhaust gas recirculation passage of an internal combustion engine so as to recirculate part of exhaust gas into a suction system of the engine in response to an EGR control signal, comprising:

  • a) detecting means for detecting an engine driving condition;

    b) combustion state related parameter measuring means for measuring a combustion state related parameter of at least one combustion chamber of engine cylinders;

    c) combustion time duration measuring means for measuring a length of a combustion time duration in one combustion stroke within the combustion chamber including at least an approximately end period of the one combustion stroke on the basis of the measured combustion state related parameter;

    d) predictive combustion time duration determining means for determining a target recirculation rate to be normally achieved by controlling an opening angle of the exhaust gas recirculation control valve means via the EGR control signal on the basis of the detected engine driving condition and for determining a length of a predictive combustion time duration on the basis of the determined target exhaust gas recirculation rate; and

    e) failure diagnosing means for comparing the length of the measured combustion time duration with that of the predictive combustion time duration so as to diagnose whether a failure occurs in the exhaust gas recirculation system according to a result of the comparison.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×