Method And Device For Indicating An Electric Discharge Inside A Bearing Of An Electric Drive System

• US 20090302864A1
• Filed: 03/12/2007
• Published: 12/10/2009
• Est. Priority Date: 03/13/2006
• Status: Active Grant

• Current Assignee: ABet SKF
• Original Assignee: ABet SKF
• Inventors: Marinov, Pavlik
• Granted Patent: US 9,140,758 B2
• Time in Patent Office: Days
• US Class Current: 324/557
• CPC Class Codes: G01R 31/1263 of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
• CPC Class Codes: G01R 31/343 in operation

Abstract

The present invention relates to a method for indicating an electric discharge in a non-conducting medium (22) between a rolling element (20) and a raceway (16, 18) in a bearing (12) of an electric drive system (10). The method comprises: remotely detecting radio frequency signals emitted from the electric drive system, which signals comprise a radio frequency signal associated with an electrical discharge in the non-conducting medium, processing the detected radio frequency signals to estimate the electric discharge, and indicating the estimated electric discharge. The present invention also relates to a corresponding device (30, 50, 70, 90) for indicating an electric discharge in a non-conducting medium between a rolling element and a raceway in a bearing of an electric drive system.

Claims

1. A method for indicating an electric discharge in a non-conducting medium between a rolling element and a raceway in a bearing of an electric drive system, comprising:

remotely detecting radio frequency signals emitted from the electric drive system, which signals include a radio frequency signal associated with an electrical discharge in the non-conducting medium,

processing the detected radio frequency signals to estimate the electric discharge, and

indicating the estimated electric discharge.

2. A method according to claim 1, wherein the electric drive system is an AC system.

3. A method according to claim 1, wherein the radio frequency signal associated with the electric discharge exhibits at least one of:

being a non-repetitive signal, being shorter than 200 ns, and having a frequency spectra within 50 MHz-8 GHz range.

4. A method according to claim 3, wherein the radio frequency signal associated with the electric discharge exhibits at least one of:

being a non-repetitive signal, being shorter than 100 ns, and having a frequency spectra within 50 MHz-1 GHz range.

5. A method according to claim 1, wherein detecting radio frequency signals comprises detecting a magnetic field associated with the electrical discharge using a magnetic field sensor.

6. A method according to claim 5, wherein the magnetic field sensor includes a closed loop antenna.

7. A method according to claim 6, wherein the antenna is a wide band antenna with low Q factor.

8. A method according to claim 1, wherein detecting radio frequency signals includes detecting an electric field associated with the electrical discharge using an electric field sensor.

9. A method according to claim 8, wherein processing the detected radio frequency signals includes verifying the electric discharge estimated from the detected magnetic field by means of the detected electric field.

10. A method according to claim 1, wherein processing the detected radio frequency signals includes filtering the detected radio frequency signals to reduce non-discharge noise.

11. A method according to claim 1, further comprising comparing the estimated electric discharge to a preset threshold, wherein the indication of the estimated electric discharge is carried out when the estimated electric discharge exceeds the preset threshold.

12. A device for indicating an electric discharge in a non-conducting medium between a rolling element and a raceway in a bearing of an electric drive system, comprising:

means for remotely detecting radio frequency signals emitted from the electric drive system, which signals comprises a radio frequency signal associated with an electrical discharge in the non-conducting medium,

means for processing the detected radio frequency signals to estimate the electric discharge, and

means for indicating the estimated electric discharge.

13. A device according to claim 12, wherein the electric drive system is an AC system.

14. A device according to claim 12, wherein the radio frequency signal associated with the electric discharge exhibits at least one of:

being a non-repetitive signal, being shorter than 200 ns, and having a frequency spectra within 50 MHz-8 GHz range.

15. A device according to claim 14, wherein the radio frequency signal associated with the electric discharge exhibits at least one of:

being a non-repetitive signal, being shorter than 100 ns, and having a frequency spectra within 50 MHz-1 GHz range.

16. A device according to claim 12, wherein the means for detecting radio frequency signals includes a magnetic field sensor for detecting a magnetic field associated with the electrical discharge.

17. A device according to claim 16, wherein the magnetic field sensor includes a closed loop antenna.

18. A device according to claim 17, wherein the antenna is a wide band antenna with low Q factor.

19. A device according to claim 12, wherein the means for detecting the radio frequency signals includes an electric field sensor for detecting an electric field associated with the electrical discharge.

20. A device according to claim 19, wherein the means for processing the detected radio frequency signals is adapted to verify the electric discharge estimated from the detected magnetic field by means of the detected electric field.

21. A device according to claim 12, wherein the means for processing the detected radio frequency signals includes means for filtering the detected radio frequency signals to reduce non-discharge noise.

22. A device according to claim 12, further comprising means for comparing the estimated electric discharge to a preset threshold, wherein the means for indicating the estimated electric discharge is actuated when the estimated electric discharge exceeds the preset threshold.