Acoustic detection of bearing defects

• US 4,843,885 A
• Filed: 03/16/1988
• Issued: 07/04/1989
• Est. Priority Date: 10/02/1987
• Status: Expired due to Fees

• Current Assignee: Business Alliance Capital Corp. (Banco Santander SA)
• Original Assignee: Servo Corporation of America
• Inventors: Bambara, Joseph E.
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): Arana, Louis M.
• Application Number:
  US07/168,975
• Time in Patent Office: 475 Days
• Field of Search: 73/660, 73/659, 73/649, 246/169 S, 246/169 R, 246/169 A, 246/169 D, 246/DIG. 1
• US Class Current: 73/660
• CPC Class Codes: B61K 9/04 Detectors for indicating the overheating of axle bearings and the like, e.g. associated with the brake system for applying the brakes in case of a fault
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis
• CPC Class Codes: G01N 2291/2696 Wheels, Gears, Bearings
• 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

Abstract

An apparatus for the detection of impact frequencies in moving railway train bearings which are characteristic of bearing defects. The apparatus transduces acoustic vibrations of the bearings into an electrical signal and extracts an envelope modulated carrier frequency component from the electric signal. The envelope is extracted from the carrier frequency component and is analyzed by a bandpass filter. The bandpass filter includes a switch capacitor filter controlled by a master clock which, in turn, is controlled by train speed and/or direction sensors positioned along the track on which the train travels.

Claims

1. In an apparatus for monitoring bearings of a railway train for defects during operation of the train along a section of track, said apparatus being of the type including train speed sensing means, means for transducing acoustic vibrations in said bearings into an electric signal, filter means for extracting an envelope modulated carrier frequency component from said electric signal, envelope detector means for extracting the envelope which modulates said carrier frequency component, and bandpass filter means for analyzing said envelope, the improvement wherein said bandpass filter includes switch capacitor filter means controlled by a master clock and said master clock is controlled by said train speed sensing means.

2. The apparatus in accordance with claim 1 further comprising an amplifier for adjusting the gain of said apparatus, said amplifier in turn being controlled by said train speed sensing means.

3. The apparatus in accordance with claim 1 further comprising load sensing means and an amplifier for adjusting the gain of said apparatus, said amplifier in turn being controlled by said load sensing means.

4. The apparatus in accordance with claim 1 wherein said bandpass filter means includes a plurality of filter elements operating in parallel, each of said elements includes switch capacitor filter means connected to the output of said master clock, thereby controlling frequency characteristics of said switch capacitor filter means.

5. The apparatus in accordance with claim 1 wherein said train speed sensing means includes a pair of spaced apart wheel sensors along said section of track and said master clock is further controlled by the sequence in which said wheel sensors are activated;

and

wherein said apparatus further comprises recording means to correlate alarm output from said bandpass filter means to a count of axles from said wheel sensors.

6. The apparatus in accordance with claim 5 for further comprising load sensing means.

7. The apparatus in accordance with claim 1 wherein said transducing means includes two microphone assemblies, one of said assemblies placed on each side of the section of track, substantially four feet away from the section of track, and optimized to detect sounds within substantially thirty degrees in both horizontal directions from a line perpendicular to the section of track.

8. The apparatus in accordance with claim 7 where both of said microphones assemblies include a tone generating means for simulating the passage of bearing with possible defects for calibration and testing of the other of said microphone assemblies.