Rolling bearing and sensor-equipped rolling bearing

Patent metadata

Field	Value
Publication number	US-12000435-B2
Application number	US-202017438385-A
Country	US
Kind code	B2
Filing date	Mar 11, 2020
Priority date	Mar 11, 2019
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

Abstract

A rolling bearing according to an embodiment includes a stationary ring having a first facing surface, a rotating ring having a second facing surface facing the first facing surface, and rotating relative to the stationary ring, rolling elements arranged between the first facing surface and the second facing surface, a cage that retains the rolling elements, first electrodes and second electrodes fixed in position relative to the stationary ring and arranged in a bearing space between the stationary ring and the rotating ring, third electrodes fixed in position relative to the rotating ring, position relative to the rolling elements, or position relative to the cage and arranged in the bearing space, and an insulating film formed on surfaces of the first electrodes and the second electrodes or surfaces of the third electrodes.

First claim

The invention claimed is:

1. A rolling bearing comprising:
a stationary ring having a first facing surface;
a rotating ring having a second facing surface facing the first facing surface, the rotating ring rotating relative to the stationary ring;
rolling elements arranged between the first facing surface and the second facing surface;
a cage that retains the rolling elements;
first electrodes and second electrodes;
third electrodes fixed in position relative to the rotating ring, the rolling elements, or the cage;
an insulating film formed on surfaces of the first electrodes and the second electrodes; and
a lubricant, wherein
the third electrodes are each arranged such that a first distance that is a distance from the first electrode and a second distance that is a distance from the second electrode change with rotation of the rotating ring relative to the stationary ring,
the first electrodes and the second electrodes are alternately arranged along a circumferential direction such that a phase of temporal change of the first distance is shifted from a phase of temporal change of the second distance, and
the third electrodes and the insulating film slide on each other with the lubricant interposed in accordance with rotation of the rotating ring relative to the stationary ring so as to generate electricity in the first electrodes and the second electrodes.

2. The rolling bearing according to claim 1 , wherein
the first electrodes and the second electrodes are arranged in a bearing space between the stationary ring and the rotating ring and are fixed in position relative to the stationary ring, and
the third electrodes are arranged in the bearing space and fixed in position relative to the rotating ring.

3. The rolling bearing according to claim 2 , further comprising a first annular member formed of a conductive material and attached to the second facing surface, wherein
the first annular member has a first surface facing the first facing surface and a second surface facing the second facing surface,
the first surface has a protrusion projecting toward the first facing surface, and
the protrusion forms the third electrode.

4. The rolling bearing according to claim 2 , further comprising an annular member attached to the second facing surface, wherein
the annular member has a first surface facing the first facing surface and a second surface facing the second facing surface, and
the first surface has a depression recessed toward the second surface, the third electrode being arranged in the depression.

5. The rolling bearing according to claim 2 , further comprising a substrate having an annular shape and attached to the first facing surface, wherein
the substrate has a third surface facing the second facing surface and a fourth surface facing the first facing surface, and
the first electrodes and the second electrodes are formed on the third surface.

6. The rolling bearing according to claim 2 , further comprising a seal member at least partially closing the bearing space,
wherein the first electrodes and the second electrodes are arranged on a surface on the bearing space side of the seal member.

7. The rolling bearing according to claim 2 , wherein the first electrodes and the second electrodes are formed at the stationary ring.

8. The rolling bearing according to claim 2 , wherein the third electrodes are formed at the rotating ring.

9. The rolling bearing according to claim 2 , wherein
the first electrodes and the second electrodes are alternately arranged at regular intervals along a circumferential direction,
the third electrodes are arranged at regular intervals along the circumferential direction, and
the number of the third electrodes is equal to the number of the first electrodes and the number of the second electrodes.

10. The rolling bearing according to claim 2 , further comprising a coating film formed on at least one of the insulating film and on the third electrodes.

11. The rolling bearing according to claim 10 , wherein the coating film is formed of DLC.

12. The rolling bearing according to claim 10 , wherein the coating film is formed of an alloy containing nickel.

13. The rolling bearing according to claim 2 , wherein the insulating film is formed of DLC.

14. The rolling bearing according to claim 1 , wherein the insulating film has a thickness equal to or less than 100 μm.

15. The rolling bearing according to claim 1 , wherein the rolling elements or the cage serves as the third electrodes.

16. The rolling bearing according to claim 15 , wherein
the rolling elements are balls,
the cage serves as the third electrodes, and
the cage has a protrusion projecting along a center axial direction at a portion retaining each rolling element.

17. The rolling bearing according to claim 15 , wherein
the rolling elements are arranged at regular intervals along a circumferential direction,
the number of the first electrodes and the number of the second electrodes are each an integer multiple of the number of the rolling elements, and
the first electrodes and the second electrodes are alternately arranged at regular intervals along the circumferential direction.

18. The rolling bearing according to claim 15 , wherein
the cage serves as the third electrodes, and
a surface of the cage that faces the first electrodes has protrusions each projecting toward the first electrode.

19. The rolling bearing according to claim 18 , wherein
the protrusions are arranged at regular intervals along a circumferential direction,
the number of the first electrodes and the number of the second electrodes are each an integer multiple of the number of the protrusions, and
the first electrodes and the second electrodes are alternately arranged at regular intervals along the circumferential direction.

20. The rolling bearing according to claim 15 , further comprising a seal member defining a bearing space between the stationary ring and the rotating ring,
wherein the first electrodes and the second electrodes are arranged on a surface on the bearing space side of the seal member.

21. The rolling bearing according to claim 15 , wherein
the insulating film is a film formed of an electrifiable material, and
the insulating film is a polytetrafluoroethylene film.

22. The rolling bearing according to claim 15 , wherein the insulating film has a thickness equal to or less than 100 μm.

23. A sensor-equipped rolling bearing assembly comprising:
a rolling bearing of claim 15 ; and
a detection unit that detects a revolution speed of the cage based on a voltage between the first electrode and the second electrode.

24. The sensor-equipped rolling bearing according to claim 23 , wherein the detection unit is capable of estimating a relative rotation speed of the stationary ring to the rotating ring based on the revolution speed of the cage.

25. A sensor-equipped rolling bearing assembly comprising:
a rolling bearing of claim 1 ; and
a detection unit that detects a state of lubricant supplied in interior of the rolling bearing based on a voltage between the first electrode and the second electrode.

26. The sensor-equipped rolling bearing according to claim 25 , wherein the state of the lubricant detected by the detection unit is the amount of water contained in the lubricant.

Assignees

• The School Corporation Kansai Univ
• Ntn Toyo Bearing Co Ltd

Inventors

• Tani Hiroshi
• Hakamata Hiroyuki
• Shibuya Yusuke
• Yamaguchi Sota

Classifications

• F16C41/007 Primary

  Encoders, e.g. parts with a plurality of alternating magnetic poles · CPC title

• F16C41/004 Primary

  Electro-dynamic machines, e.g. motors, generators, actuators · CPC title

• G01P3/481

  of pulse signals · CPC title

• H02N1/08

  with conductive charge carrier, i.e. capacitor machines · CPC title

• H02N1/10

  with non-conductive charge carrier · CPC title