Bearing defect detection using time synchronous averaging (TSA) of an enveloped accelerometer signal

• US 6,681,634 B2
• Filed: 12/11/2001
• Issued: 01/27/2004
• Est. Priority Date: 12/11/2001
• Status: Active Grant

• Current Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Sabini, Eugene P., Lorenc, Jerome A., Hauenstein, Kenneth L., Henyan, Oakley
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Miller, Rose M.
• Application Number:
  US10/014,044
• Publication Number:
  US 20030106375A1
• Time in Patent Office: 777 Days
• Field of Search: 736/60, 736/59, 736/58, 736/61, 735/93
• US Class Current: 73/593
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis
• CPC Class Codes: G01N 2291/2696 Wheels, Gears, Bearings
• CPC Class Codes: G01N 2291/2698 Other discrete objects, e.g. bricks
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/449 Statistical methods not provided for in G01N29/4409, e.g. averaging, smoothing and interpolation

Abstract

A method is provided of identifying a rotating bearing defect featuring the steps of measuring the vibration of the rotating bearing to obtain a waveform signal; filtering the waveform signal to remove unwanted signal frequencies; enveloping the filtered waveform signal to obtain an enveloped low frequency time waveform; and synchronizing the enveloped low frequency time waveform to the running speed of the rotating bearing in such a way to preserve the phase relationship between the tachometer pulse and bearing defect to obtain a time synchronized waveform. The method may include the step of measuring the rotational speed of the rotating bearing; and the step of measuring the rotational speed of the rotating bearing comprises measuring the rotational speed of the rotating bearing with a tachometer.

Claims

1. A method of identifying a rotating bearing defect comprising the steps of:

measuring a rotational speed of a rotating bearing;

measuring a vibration of the rotating bearing to obtain a waveform signal;

filtering the waveform signal to remove unwanted signal frequencies;

enveloping a filtered waveform signal to obtain an enveloped low frequency time waveform; and

synchronizing the enveloped low frequency time waveform to the running speed of the rotating bearing in such a way to preserve a phase relationship between a tachometer pulse and bearing defect to obtain a time synchronized waveform.

2. The method of claim 1 wherein the step of measuring the rotational speed of the rotating bearing comprises measuring the rotational speed of the rotating bearing with a tachometer.

3. The method of claim 1 wherein the step of measuring the vibration of the rotating bearing comprises measuring the vibration generated at least in part by the rotating bearing using an accelerometer.

4. The method of claim 3 wherein the bandpass filter filters about the natural frequency of the accelerometer.

5. The method of claim 1 wherein the step of filtering the waveform signal comprises filtering the waveform signal using a bandpass filter.

6. The method of claim 1 further comprising the step of storing the time synchronized waveform in a database.

7. The method of claim 6 further comprising the step of averaging the time synchronized waveform with at least one previously stored time synchronized waveform to obtain an average time synchronized waveform (TSA).

8. The method of claim 7 further comprising the step of spectrum analyzing the TSA.

9. The method of claim 8 further comprising the step of identifying an amplitude of the TSA at rotating bearing defect frequencies and their multiples.

10. The method of claim 8 further comprising the step of identifying bearing defect frequencies above a threshold.

11. The method of claim 1 further comprising the step of determining whether the rotational speed of the rotating bearing is within a predetermined range.

12. A method of identifying a rotating bearing defect comprising the steps of:

measuring a vibration generated at least in part by the rotating bearing using an accelerometer to obtain a waveform signal;

filtering the waveform signal using a bandpass filter to remove unwanted signal frequencies;

enveloping the filtered waveform signal to obtain an enveloped low frequency time waveform;

measuring the rotational speed of the rotating bearing;

synchronizing the enveloped low frequency time waveform to the rotational speed of the rotating bearing in such a way to preserve the phase relationship between the tachometer pulse and bearing defect to obtain a time synchronized waveform;

averaging the time-synchronized waveform with at least one previously stored time synchronized waveform to obtain an average time synchronized waveform (TSA);

spectrum analyzing the TSA; and

identifying an amplitude of the TSA at rotating bearing defect frequencies and their multiples.

13. A method for identifying defects in a rolling bearing, comprising the steps of:

measuring a rotational speed of a rolling bearing;

measuring a vibration generated by said rolling bearing using an accelerometer for generating an accelerometer signal,

time synchronous averaging said accelerometer signal to remove vibration frequencies which are not in synchronism to the rotational speed of said rolling bearing;

analyzing an averaged signal to obtain bearing defect frequencies indicative of the extent of a bearing defect.

14. The method according to claim 13 further including the steps of:

filtering said accelerometer signal prior to the step of time synchronous averaging to remove unwanted signal frequencies.

15. The method according to claim 14 further including the step of providing an envelope signal from a filtered signal.

16. The method according to claim 15 further including the step of synchronizing a rotational speed signal with said envelope signal.

17. The method according to claim 15 wherein the step of providing an envelope signal includes processing said filtered signal by a signal smoothing technique to provide said envelope signal.

18. The method according to claim 17 wherein said signal smoothing technique employs a Hilbert transform.