Patent ID: 6389887
Filing Date: 2002-05-21
Classification: G01H,G01M

Abstract:
A process for early detection of an appearance of a fault in a component of a first engine, said process comprising:a preliminary phase of investigation using a second engine with a same design as said first to identify, for at least one operating speed of the engine, frequency spectral lines present during operation of the second engine without a fault and then with the fault so as to identify specific spectral lines for the fault and a detection phase during which t he following steps are carried out in an iterative manner in the course of operation of the second engine: acquiring a string of digital samples representative of a vibratory acceleration signal in the course of an acquisition sequence; checking that the speed of the second engine has remained stable during said acquisition sequence; and applying to stable sequences acquired the following processing operations in real time during operation of the second engine or in delayed time: transforming the signal acquired by temporal sampling into a frequency signal, while eliminating fundamental frequencies of the second engine and harmonic characteristics thereof, performing at least one normed coherence calculation between said frequency signal and the same frequency signal shifted by a frequency value corresponding to a value of one of the frequency spectral lines of the fault detected during said preliminary phase, comparing a value of a coherence peak obtained by the coherence calculation with a first threshold and storing a 1 detection value if said peak is greater than said first threshold and a 0 value if said peak is not greater than said first threshold, summing P stored detection values a and dividing the sum obtained by P to provide a detection ratio, and deeming a fault to be present if said detection ratio is greater than or equal to a second predetermined threshold.