Method and apparatus for diagnosing machine condition

• US 4,530,240 A
• Filed: 11/15/1983
• Issued: 07/23/1985
• Est. Priority Date: 11/15/1983
• Status: Expired due to Fees

• Current Assignee: Diagnostic Equipment Development Incorporated
• Original Assignee: Diagnostic Equipment Development Incorporated
• Inventors: Board, David B., Cooper, William J.
• Primary Examiner(s): Ciarlante, Anthony V.
• Application Number:
  US06/551,892
• Time in Patent Office: 616 Days
• Field of Search: 73/593, 73/660
• US Class Current: 73/593
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• 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

For use in predicting machine failure a transducer sensor, such as piezoelectric crystal, is applied to a machine for sensing machine motion and structure borne sound, including vibration friction, and shock waves. The structure borne sound and motion sensed is converted to electrical signals which are filtered to leave only the friction and shock waves, which waves are processed, as by detecting the envelope and integrating beneath the envelope, resulting in a measure of friction and shock wave energy. This measure may be compared with that of a less used machine, say the same machine when new, to indicate the rise in energy due to change in machine parts.

Claims

1. Apparatus for predicting failures in rotary equipment including bearings, gears and the like, said apparatus comprising:

a transducing sensor for attachment to the equipment to produce electrical signals corresponding to vibration and friction and shock waves in the equipment;

band pass filter means connected to the sensor for filtering out the signals corresponding to vibration and passing only signals corresponding to friction and shock waves in a frequency band around the natural frequency of said sensor;

detector means connected to said filter means for detecting the envelope of signals in said frequency band;

integrating means connected to said detector means for integrating the envelopes of said friction and shock signals as a measure of friction and shock wave energy; and

full wave rectifier means between said band pass filter means and detector means, for maximum information utilization, said integrating means comprising voltage to frequency converter means connected to said detector means, and counter means connected to said voltage to frequency converter means.

2. Apparatus for predicting failure in rotary equipment including bearings, gears and the like, said apparatus comprising:

a transducing sensor for attachment to the equipment to produce electrical signals corresponding to vibration and friction and shock waves in the equipment;

band pass filter means connected to the sensor for filtering out the signals corresponding to vibration and passing only signals corresponding to friction and shock waves in a frequency band around the natural frequency of said sensor;

detector means connected to said filter means for detecting the envelope of signals in said frequency band;

integrating means connected to said detector means for integrating the envelopes of said friction and shock signals as a measure of friction and shock wave energy, said integrating means comprising voltage to frequency converter means connected to said detector means, and counter means connected to said voltage to frequency converter means.

3. The method of diagnosing machine wear comprising the steps of:

sensing machine motion including (a) vibration and (b) friction and shock waves;

converting the motion sensed to electrical signals;

filtering out the vibration signals to leave friction and shock waves signals; and

integrating the friction and shock wave signals to obtain a measure of friction and shock wave energy, for comparison with a measure of friction and shock wave energy of a less used machine, wherein said integrating is by voltage to frequency conversion and counting.

4. The method of diagnosing machine wear comprising the steps of:

sensing machine motion including (a) vibration and (b) friction and shock waves;

converting the motion sensed to electrical signals;

filtering out the vibration signals to leave the friction and shock wave signals;

integrating the friction and shock wave signals to obtain a measure of friction and shock wave energy, for comparison with a measure of friction and shock wave energy of a less used machine;

filtering out frequencies of said friction and shock wave signals except in the region of the natural frequency of the sensor used to pass a frequency band of said friction and shock wave signals;

rectifying the signals of said frequency band; and

detecting the envelope of said rectified signals for integration of the envelope, wherein said integrating is by voltage to frequency conversion and counting.