Apparatus and method for diagnosing occurrence of failure in variable valve timing control system for internal combustion engine
First Claim
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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.
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Abstract
In a diagnosing apparatus and method for an internal combustion engine having a variable valve timing control system, the apparatus and method diagnose whether the variable valve timing control system actually switches the valve timings according to a switching between an operation and non-operation of the variable valve timing control system, utilizing a variation occurrence in an intake air pulsation in response to the switching between an operation mode and non-operation mode of the variable valve timing control system.
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Citations
21 Claims
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1. A diagnosing apparatus for an internal combustion engine, comprising:
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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 Dependent Claims (2, 3, 4, 5, 6)
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7. A diagnosing apparatus for an internal combustion engine, comprising:
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a) variable valve timing control system having a solenoid, said solenoid being excited in response to a first predetermined level signal and being deenergized in response to a second predetermined level signal; b) an intake airflow meter arranged in an intake air system of the engine to detect an intake air quantity entering the engine and output a signal indicating the intake air quantity; c) engine driving condition detecting means for detecting at least one engine driving condition determining parameter; d) intake air pulsation region determining means for determining whether the engine falls in an engine driving region where intake air pulsation occurs on the basis of the engine driving condition determining parameter; e) first intake air pulsation period measuring means for measuring at least one of a first intake air pulsation period and a frequency of the intake air pulsation when said variable valve timing control system is operated to excite the solenoid in response to the first predetermined level signal and when said intake air pulsation region determining means determines that the engine falls in the engine driving region; f) second intake air pulsation period measuring means for measuring at least one of a second intake air pulsation period and the frequency of the intake air pulsation when said variable valve timing control system is operated to deenergize the solenoid in response to the second predetermined level signal and when said intake air pulsation region determining means determines that the engine falls in the engine driving region; g) intake air pulsation comparing means for comparing said first and second intake air pulsation periods or frequencies measured by the first and second intake air pulsation period measuring means; and h) determining means for determining whether a failure in said variable valve timing control system occurs according to a result of the comparison made by the intake air pulsation comparing means. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A diagnosing method for an internal combustion engine having a variable valve timing control system having a solenoid, said solenoid being excited in response to a first predetermined level signal so that the variable valve timing control system is operated and being deenergized in response to a second predetermined level signal so that the variable valve timing control system is not operated, said diagnosing method comprising the steps of:
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a) detecting an intake air quantity of the engine and outputting a signal indicating the intake air quantity; b) detecting at least one engine driving condition determining parameter; c) determining whether the engine falls in an engine driving region wherein intake air pulsation occurs on the basis of the engine driving condition determining parameter; d) measuring at least one of a first intake air pulsation period and a frequency of the intake air pulsation when said variable valve timing control system is operated according to the excited solenoid in response to the first predetermined level signal and when, at the step c), it is determined that the engine falls in the engine driving region; e) measuring at least one of a second intake air pulsation period and the frequency of the intake air pulsation when said variable valve timing control system is operated according to the deenergized solenoid in response to the second predetermined level signal and when, at the step c), it is determined that the engine falls in the engine driving region; f) comparing said first and second intake air pulsation periods or frequencies measured in steps d) and e); and g) determining whether a failure in said variable valve timing control system occurs according to a result of the comparison at step f). - View Dependent Claims (21)
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Specification