Cyclic time averaging for machine monitoring

• US 20050021250A1
• Filed: 07/30/2004
• Published: 01/27/2005
• Est. Priority Date: 12/04/2001
• Status: Active Grant

• Current Assignee: SKF USA Incorporated (SKF)
• Original Assignee: Johannes I. Boerhout
• Inventors: Boerhout, Johannes I.
• Granted Patent: US 7,289,919 B2
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G05B 23/0235 based on a comparison with predetermined threshold or range, e.g. "classical methods", carried out during normal operation; threshold adaptation or choice; when or how to compare with the threshold

Abstract

A cyclic time averaging method is directed at processing time-domain vibration data of the machine to produce an averaged time waveform over a selected cyclic time period. It is not necessary to employ a triggering signal to obtain the averaged time waveform.

Claims

1. A system for analyzing vibration data configured to receive a plurality of vibration amplitude samples taken at discrete sampling times, said system comprising:

a first module configured to estimate vibration amplitudes at times between said discrete sampling times;

a second module configured to use said estimated vibration amplitudes in performing a cyclic average.

2. The system of claim 1, wherein said first module comprises an interpolator.

3. The system of claim 2, wherein said vibration amplitude samples are taken from a machine having a characteristic repeated cyclic phenomena recurring over a period M.

4. The system of claim 3, wherein adjacent discrete sampling times are separated by a time period of 1/F_S, where F_S is a sampling frequency, and wherein period M=(n+α

)/F_S, wherein n is an integer, and a is a number between 0 and 1.

5. The system of claim 3, wherein said second module comprises an averager configured to produce an average vibration amplitude by computing the average of a first sampled value at time p and the sampled or interpolated vibration amplitude value at one or more later times p+m(n+α

), where m is an integer.