Method for determining and displaying spectra for vibration signals

• US 6,208,944 B1
• Filed: 06/26/1998
• Issued: 03/27/2001
• Est. Priority Date: 06/26/1997
• Status: Expired due to Fees

• Current Assignee: PRÜFTECHNIK Dieter Busch AG (Fortive Corp.)
• Original Assignee: PRÜFTECHNIK Dieter Busch AG (Fortive Corp.)
• Inventors: Loesl, Johann, Buehler, Steffen, Franke, Dieter
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/105,303
• Time in Patent Office: 1,005 Days
• Field of Search: 702/56, 702/75-77, 702/189-190, 702/191, 736/59, 736/60, 340/680, 340/683
• US Class Current: 702/56
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence

Abstract

A portable electronic vibration measurement device, detects a large number of structure-borne sound signals using a predetermined sequence of a plurality of specific individual measurements each plurality of measurements taken at a different sampling frequency.

Claims

1. A method for gathering vibration data representing a measured vibration from a vibration sensor on a machine, said method comprising the steps of:

receiving a first number of vibration signals in a data gatherer from said vibration sensor, said first number of vibration signals being sampled at a first sampling frequency, wherein said first sampling frequency is determined based upon a desired resolution of signal components in a first frequency band;

receiving a second number of vibration signals in a data gatherer from said vibration sensor, said second number of vibration signals being sampled at a second sampling frequency, wherein said second sampling frequency is determined based upon a desired resolution of signal components in a second frequency band, said second sampling frequency being different from said first sampling frequency;

processing said first number of vibration signals and said second number of vibration signals using said data gatherer;

storing said first number of vibration signals and said second number of vibration signals in said data gatherer;

subjecting said first number of vibration signals and said second number of vibration signals to frequency analysis to form corresponding first and second frequency spectra; and

combining said first and second frequency spectra to form an overall frequency spectrum.

2. The method of claim 1, wherein said first sampling frequency and said second sampling frequency are related.

3. The method of claim 2, further comprising the steps of:

prior to said first receiving step, conducting an advance analysis to determine frequency bands of interest and basing said first and second sampling frequencies upon those frequency bands of interest.

4. The method of claim 3, wherein said advance analysis comprises determining whether a signal component from said vibration sensor has a signal intensity that exceeds a predetermined threshold value.

5. The method of claim 2, wherein said first and second sampling frequencies are related such that the frequency bands are staggered based upon size and such that individual spectra can be superimposed, stored, transmitted and displayed together as an overall spectral combination.

6. The method of claim 1, further comprising storing said frequency spectrum in a single data set.

7. The method of claim 1, wherein subjecting step comprises performing a discrete fourier transformation with a constant absolute narrowband bandwidth in which results of such a transformation are ordered based upon individual frequencies and are reproduced based upon one of magnitude, phase and complex-value results.

8. The method of claim 1, further comprising:

producing a frequency representation of said overall frequency spectrum; and

displaying said frequency representation.

9. The method of claim 8, wherein said displaying of said frequency representation comprises displaying said frequency representation in a rectangular coordinate system, wherein the abscissa of said system is visually sectioned to distinguish said first frequency spectrum from said second frequency spectrum.

10. The method of claim 9, wherein said frequency representation display sections each have an identical scale and different scale end values and different absolute frequency resolutions.

11. The method of claim 8, wherein said step of producing a frequency representation omits overlapping information from said first and second frequency spectra.

12. The method of claim 8, wherein said displaying step is in response to a single display command.

13. The method of claim 12, wherein said displaying step is based upon predefined settings contained in said display command.

14. The method of claim 1, wherein said receiving steps are in response to a receipt of a single measurement command.

15. The method of claim 14, wherein said single measurement command includes an upper cut-off frequency and resolution for each of said first and second sampling frequencies.

16. The method of claim 15, wherein said single measurement command is received via a graphical user interface that includes one of a keyboard and a cursor.

17. The method of claim 15, further comprising the step of receiving a third number of vibration signals in a data gatherer from said vibration sensor, said third number of vibration signals being sampled at a third sampling frequency, wherein said third sampling frequency is determined based upon a desired resolution of signal components in a third frequency band, said third sampling frequency being different from said first and second sampling frequencies, wherein said upper cutoff frequency for said first, second and third sampling frequencies are in a 1:

10;

100 ratio.

18. The method of claim 17, wherein the upper cut-off frequencies for said corresponding first, second and third sampling frequencies are 0 to 400 hertz, 400 to 4000 hertz and 4000 hertz to 40,000 hertz, respectively.

19. The method of claim 1, further comprising the step of determining the sequence of receiving said first and second number of vibration signals based upon an predetermined pattern.

20. The method of claim 19, wherein said predetermined pattern is based upon one of a sequence and probability distribution of parts of the frequency bands.

21. The method of claim 20, further comprising the steps of:

repeating said receiving steps;

calculating individual fourier-transformed spectra; and

combining said individual fourier-transformed spectra to form an average spectrum.

22. The method of claim 1, further comprising the steps of repeating said receiving steps for each of a plurality of vibration sensors on said machine.

23. An apparatus for determining and displaying spectra for measured vibration of a machine, wherein said vibration is measured using a vibration sensor, said apparatus comprising:

means for receiving a first number of vibration signals from said vibration sensor, said first number of vibration signals being sampled at a first sampling frequency, wherein said first sampling frequency is determined based upon a desired resolution of signal components in a first frequency band;

means for receiving a second number of vibration signals from said vibration sensor, said second number of vibration signals being sampled at a second sampling frequency, wherein said second sampling frequency is determined based upon a desired resolution of signal components in a second frequency band, said second sampling frequency being different from said first sampling frequency;

means for processing said first number of vibration signals and said second number of vibration signals;

storage for said first number of vibration signals and said second number of vibration signals;

means for subjecting said first number of vibration signals and said second number of vibration signals to frequency analysis to form corresponding first and second frequency spectra; and

means for combining said first and second frequency spectra to form an overall frequency spectrum.

24. The apparatus of claim 23, wherein said first sampling frequency and said second sampling frequency are related.

25. The apparatus of claim 23, further comprising:

means for producing a frequency representation of said overall frequency spectrum; and

a display for displaying said frequency representation.

26. The apparatus of claim 25, wherein said display displays said frequency representation in a rectangular coordinate system and wherein the abscissa of said system is visually sectioned to distinguish said first frequency spectrum from said second frequency spectrum.

27. The apparatus of claim 26, wherein said means for producing a frequency representation omits overlapping information from said first and second frequency spectra.

28. The apparatus of claim 23, further comprising means for automatic identification of frequency bands having a predefined distribution of signal intensities.

29. The apparatus of claim 28, further comprising means for detecting measurements allocatable to said identified frequency bands having a predefined distribution of signal intensities for setting a cut-off frequency of an anti-alias filter and for setting a sampling rate of an A/D converter.

30. The apparatus of claim 23, wherein said apparatus is one of a portable data gatherer, a signal analyzer and a permanently installed continuous monitor.