Method of anticipating machine failure

• US 4,615,216 A
• Filed: 06/11/1985
• Issued: 10/07/1986
• Est. Priority Date: 06/11/1985
• Status: Expired due to Fees

• Current Assignee: Rheinisch-Westfalischer Technischer Uberwachungsverein E.V.
• Original Assignee: Rheinisch-Westfalischer Technischer Uberwachungsverein E.V.
• Inventors: Vykoupil, Peter
• Primary Examiner(s): Ciarlante, Anthony V.
• Application Number:
  US06/743,584
• Time in Patent Office: 483 Days
• Field of Search: 73/593, 73/660, 340/683
• US Class Current: 73/593
• CPC Class Codes: G01N 2291/2693 Rotor or turbine parts
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00

Abstract

A method of anticipating defects in the operation of a machine, especially a rotary machine in which high-frequency and low-frequency ranges of a body-wave spectrum in a solid part of the machine are detected and respective auto-spectral density functions G₁₁ and G₂₂ are formed, the cross spectral density function G₁₂ being formed from the measurements as well. The magnitude γ² =G₁₂² /G₁₁ ·G₂₂ is formed and the defect is anticipated by an increase in the value of γ².

Claims

1. In a method of operating a machine producing body waves in a machine part and in which a measurement is made of a first body-wave parameter at a relatively high-frequency range of a frequency spectrum of said body waves and a second body-wave parameter is measured in a low-frequency range of said frequency spectrum, the improvement which comprises:

generating an auto-spectral density value G₁₁ corresponding to the measurement of said first parameter;

generating a second auto-spectral density value G₂₂ from said measurement of said second body-wave parameter;

generating a cross spectral density value G₁₂ from both of the measurements;

automatically forming the coherence function γ

² =G₁₂² /G₁₁ ·

G₂₂ ; and

detecting an increase in the value of γ

² as an anticipation of impending failure of said machine.

2. The improvement defined in claim 1, further comprising the step of cutting off operating of said machine upon a rise in the value of γ

².

3. The improvement defined in claim 1, further comprising the step of generating a product γ

² ·

G₂₂ and detecting an increase in the value of said product as representing anticipatory failure of said machine.

4. The improvement defined in claim 1, further comprising the step of terminating operation of said machine upon an increase in said product.

5. In a system for monitoring a machine generating body waves in operation for anticipation of failure of said machine, wherein a first body-wave parameter is measured on said machine in a relatively high-frequency range of a frequency spectrum of said body waves and a second body-wave parameter is measured on said machine at a relatively low frequency of said frequency spectrum, the improvement which comprises:

means for deriving respective high-frequency and low-frequency values from said measurements;

a frequency analyzing computer connected to said means for generating from said values an auto-spectral density function G₁₁ from said high-frequency value, a second auto-spectral density function G₂₂ from said low-frequency value, and a cross spectral density function G₁₂ from both values; and

a function generator connected to said computer for generating the function γ

² =G₁₂² /G₁₁ ·

G₂₂, where an increase in the value of γ

² anticipates a defect in said machine.

6. The system defined in claim 5, further comprising means responsive to an increase in a value of γ

² for automatically cutting off operation of said machine.

7. The system defined in claim 5 wherein the means for generating said high-frequency value includes a demodulator.