×

Apparatus and method for diagnosing occurrence of failure in variable valve timing control system for internal combustion engine

  • US 5,549,080 A
  • Filed: 04/28/1995
  • Issued: 08/27/1996
  • Est. Priority Date: 04/28/1994
  • Status: Expired due to Fees
First Claim
Patent Images

1. A diagnosing apparatus for an internal combustion engine, comprising:

  • a) a variable valve timing mechanism arranged on a cam sprocket of an intake air system to variably control a phase between an engine crankshaft and an intake air system cam shaft;

    b) solenoid means for controlling a hydraulic supply to operate the variable valve timing mechanism to control said phase at a first phase deviation in response to a predetermined control signal and to not operate the variable valve timing mechanism to return said phase to a second phase deviation in response to a predetermined non-control signal;

    c) engine driving condition detecting means for detecting an engine driving condition;

    d) controlling means for generating and outputting said control signal and non-control signal according to the detected engine driving condition;

    e) intake air quantity detecting means for detecting an intake air quantity of an intake air flow in the intake air system of the engine;

    f) intake air pulsation generating region estimating means for estimating whether the engine falls in an intake air pulsation region according to the detected engine driving condition;

    g) first intake air pulsation characteristic determining parameter measuring means for measuring a first value of a characteristic determining parameter of the intake air pulsation on the basis of a result of the detection of the intake air quantity detecting means when the intake air pulsation generating region estimating means estimates that the engine falls in the intake air pulsation region and when the controlling means generates and outputs the predetermined control signal to said solenoid means;

    h) second intake air pulsation characteristic determining parameter measuring means for measuring a second value of the characteristic determining parameter of the intake air pulsation when the controlling means generates and outputs the non-control signal to said solenoid means;

    i) intake air pulsation characteristic determining parameter comparing means for comparing both of said first and second values of the characteristic determining parameter of the intake air pulsations measured by said first and second intake air pulsation characteristic determining parameter measuring means; and

    j) diagnosing means for diagnosing whether a failure in at least one of said variable valve timing mechanism and said solenoid means occurs on the basis of a result of comparison between the first and second values of the characteristic determining parameter measured by said first and second intake pulsation characteristic determining parameter measuring means.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×