Capacitance measurement in a bearing

Patent metadata

Field	Value
Publication number	US-9995344-B2
Application number	US-201515308710-A
Country	US
Kind code	B2
Filing date	May 13, 2015
Priority date	May 19, 2014
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

A bearing arrangement includes a bearing having an inner race and an outer race and a plurality of rolling elements arranged between the inner and outer race such that the first race is rotatable relative the second race; bearing lubricant arranged within the bearing to lubricate the rolling elements. The bearing arrangement provides a first electrically conductive portion and a second electrically conductive portion, the first and second electrically conductive portion being electrically insulated and arranged such that at least a portion of the bearing lubricant is located between the first and second electrically conductive portion; and a capacitance meter having a first electrode connected to the first electrically conductive portion and a second electrode connected to the second electrically conductive portion, configured to measure a capacitance between the first ring and the second ring to determine a water content in the lubricant based on the measured capacitance.

First claim

The invention claimed is:

1. A bearing arrangement comprising:
a bearing having an inner race, an outer race, and a plurality of rolling elements arranged between the inner and outer race such that a first race is rotatable relative a second race;
a bearing lubricant arranged within the bearing to lubricate the rolling elements;
a first electrically conductive portion and a second electrically conductive portion, the first and second electrically conductive portion being electrically insulated and arranged such that at least a portion of the bearing lubricant is located between the first and second electrically conductive portion; and
a capacitance meter having a first electrode connected to the first electrically conductive portion and a second electrode connected to the second electrically conductive portion, configured to measure a capacitance between the first and second portion to determine a water content in the lubricant based on the measured capacitance,
wherein the first electrically conductive portion and the second electrically conductive portion is a first and a second sealing ring arranged on respective sides of the bearing, each sealing ring being electrically insulated from the bearing; and
an electrically insulating frame arranged between the sealing ring and the bearing to electrically insulate the sealing ring from the bearing.

2. The bearing arrangement according to claim 1 , further comprising a bearing housing in which the bearing is arranged, wherein the first electrically conductive portion and the second electrically conductive portion is a first and a second perforated ring arranged on respective sides of the bearing, each perforated ring being electrically insulated from the bearing.

3. The bearing arrangement according to claim 1 , further comprising a temperature sensor configured to determine the temperature of the lubricant.

4. The bearing arrangement according to claim 1 , wherein the capacitance meter is configured to measure the capacitance at various frequencies or over a sine sweep.

5. A bearing arrangement comprising:
a bearing having an inner race, an outer race, and a plurality of rolling elements arranged between the inner and outer race such that a first race is rotatable relative a second race;
a bearing lubricant arranged within the bearing to lubricate the rolling elements;
a first electrically conductive portion and a second electrically conductive portion, the first and second electrically conductive portion being electrically insulated and arranged such that at least a portion of the bearing lubricant is located between the first and second electrically conductive portion; and
a capacitance meter having a first electrode connected to the first electrically conductive portion and a second electrode connected to the second electrically conductive portion, configured to measure a capacitance between the first and second portion to determine a water content in the lubricant based on the measured capacitance,
wherein the first electrically conductive portion is a perforated ring concentrically arranged between the inner race and the outer race within the bearing,
wherein the second electrically conductive portion is a sealing ring arranged on a side of the bearing and electrically insulated from the bearing,
wherein the second electrically conductive portion is the inner or outer race of the bearing.

6. A method for determining a condition of a lubricant in a bearing comprising:
providing a housing having an inner race and an outer race; a plurality of rolling elements arranged between the inner and outer race such that a first race is rotatable relative a second race; a bearing lubricant arranged within the housing to lubricate the rolling elements; and a first electrically conductive portion and a second electrically conductive portion, the first and second electrically conductive portion being electrically insulated from each other and arranged such that at least a portion of the bearing lubricant is located between the first and second electrically conductive portion; the method comprising:
measuring a value indicative of a capacitance between the first electrically conductive portion and the second electrically conductive portion;
determining a difference between the measured value and a predetermined value; and
if the difference is larger than a first predetermined threshold value, determine that properties of the lubricant have changed,
wherein the first electrically conductive portion and the second electrically conductive portion is a first and a second sealing ring arranged on respective sides of the bearing, each sealing ring being electrically insulated from the bearing; and
wherein an electrically insulating frame is arranged between the sealing ring and the bearing to electrically insulate the sealing ring from the bearing.

7. The method according to claim 6 , wherein the step of measuring comprises measuring the capacitance.

8. The method according to claim 6 , further comprising measuring the temperature of the lubricant.

9. The method according to claim 8 , wherein the step of measuring comprises measuring the temperature derivative of the capacitance, dC/dT.

10. The method according to claim 9 , wherein the predetermined value is a previously measured value for the same bearing.

11. The method according to claim 10 , wherein if the measured value is larger than the predetermined value, it is determined that the water content of the lubricant is increased.

12. The method according to claim 9 , further comprising continuously monitoring the capacitance during operation of the bearing in a rotating machine.

13. The method according to claim 6 , wherein the step of measuring comprises measuring the capacitance at two or more different frequencies.

Assignees

• Skf Ab

Inventors

• Dittes Nicholas

Classifications

• F16C19/52

  with devices affected by abnormal or undesired conditions · CPC title

• G01M13/04

  Bearings · CPC title

• G01N33/2888

  Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30) · CPC title

• F16C2233/00

  Monitoring condition, e.g. temperature, load, vibration · CPC title

• F16C33/6688

  Lubricant compositions or properties, e.g. viscosity · CPC title