Embedded wear sensor

• US 6,080,982 A
• Filed: 05/13/1998
• Issued: 06/27/2000
• Est. Priority Date: 05/13/1998
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Cohen, Edward Isaac
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US09/076,918
• Time in Patent Office: 776 Days
• Field of Search: 250/227.11, 250/227.14, 250/358.1, 73/86, 73/116, 73/118.1, 310/68 R, 340/672, 340/682
• US Class Current: 250/227.11
• CPC Class Codes: B63B 79/10 using sensors, e.g. pressure sensors, strain gauges or accelerometers
• CPC Class Codes: B63H 23/321 Bearings or seals specially adapted for propeller shafts
• CPC Class Codes: F16C 17/246 related to wear, e.g. sensors for measuring wear
• CPC Class Codes: F16C 2233/00 Monitoring condition, e.g. temperature, load, vibration
• CPC Class Codes: F16C 2326/30 Ships, e.g. propelling shafts and bearings therefor in general B63H
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

Fiber optic filaments are embedded at a bearing surface. In the context of a mechanical bearing system, the filaments wear as the surface wears. Based on the observed amount of light which is transmitted through the filaments, the degradation of the filaments is related in a measurable way to the wear of the bearing surface. The sole power requisite for inventive operation is light, for observation purposes. As compared with convention approaches to wear measurement, the invention more accurately measures wear of the bearing itself and is therefore a better predictor of servicing requirements. Inventive practice of remote wear monitoring is a viable and preferable option.

Claims

1. The wear detector combination comprising a bearing member and a fiber optic line, said fiber optic line including at least one optical fiber, said bearing member including a bearing surface, said fiber optic line accessing and exiting said bearing member whereby a segment of said fiber optic line is embedded at said bearing surface.

2. The wear detector combination as in claim 1 comprising a light emitter and a light receptor, said light emitter connected at a first end of said fiber optic line, said light receptor connected at a second end of said fiber optic line, wherein said bearing surface is for sliding contact with a relatively moving body, wherein said light emitter emits a first amount of light, wherein said light receptor receives a second amount of light which follows the transmission of said first amount of light through said segment of said fiber optic line, and wherein the diminution of said second amount of light versus said first amount of light is a function of the deterioration of said segment of said fiber optic line.

3. The wear detector combination as in claim 2, wherein said deterioration of said segment of said fiber optic line is commensurate with the wear of said bearing surface.

4. The wear detector combination as in claim 2, wherein said diminution of said second amount of light is evidential, of said wear of said bearing surface.

5. The wear detector combination as in claim 4, wherein said bearing member includes a bearing wear portion which includes a lower wear portion demarcation and at least a part of said bearing surface, said bearing wear portion is generally characterized by a wear portion thickness which is approximately the distance between said bearing surface and said lower wear portion demarcation, said fiber optic line is generally characterized by a line width, and said segment of said fiber optic line is embedded at said bearing surface in said bearing wear portion to a depth which approximately ranges between one-half said line width below said bearing surface and one-half said line width below said lower wear portion demarcation.

6. A wear-sensing device comprising fiber optic means and bearing means, said bearing means having passage means and an inwardly-facing surface which is provided with channel means communicating with said passage means, said bearing means thereby being adapted to accommodating ingress and egress of said fiber optic means whereby said channel means retains a portion of said fiber optic means, and whereby said portion of said fiber optic means is nearly flush with respect to said inwardly-facing surface.

7. A wear-sensing device as in claim 6, wherein:

said inwardly-facing surface is for slidably contacting another object;

a degree of disintegration of said portion of said fiber optic means results from said slidably contacting;

a degree of wear of said inwardly-facing surface results from said slidably contacting; and

said degree of disintegration is indicative of said degree of wear.

8. A wear-sensing device as in claim 7 comprising a light source and data acquisition means, wherein light originates from said light source and is transmitted by said fiber optic means to said data acquisition means, wherein reduction of said light occurs in accordance with said degree of disintegration of said portion of said fiber optic means, wherein said data acquisition means includes means for correlating said reduction of said light with said degree of wear of said inwardly-facing surface, and wherein said data acquisition means includes means for displaying information pertaining to said correlating.

9. A wear-sensing device as in claim 6, wherein said fiber optic means includes at least one optical fiber.

10. A wear-sensing device as in claim 9, wherein said fiber optic means includes a plurality of optical fibers which are bundled.

11. A wear-sensing device as in claim 9, wherein said fiber optic means includes a plurality of optical fibers which are discrete.

12. A wear-sensing device as in claim 9, wherein:

said bearing means has a wear portion which includes at least a portion of said inwardly-facing surface and a selected delimitation, said selected delimitation being generally opposite said at least a portion of said inwardly facing surface;

said fiber optic means has an approximate imaginary centerline and an approximate diameter;

the portion of said centerline which corresponds to said portion of said fiber optic means is generally situated in said wear portion in the range between approximate coincidence of said centerline with said at least a portion of said inwardly-facing surface and approximate coincidence of said centerline with said selected delimitation.

13. A wear-sensing device as in claim 6, wherein:

said bearing means includes a continuous-surface bearing;

said inwardly-facing surface is an inwardly-facing surface of said continuous-surface bearing, said inwardly-facing surface having a so circumference and a curvilinear shape in the circumferential direction; and

said portion of said fiber optic means is retained by said channel means so as to be disposed approximately in said circumferential direction over at least a part of said circumference.

14. A wear-sensing device as in claim 6, wherein:

said bearing means includes a discontinuous-surface bearing, said discontinuous-surface bearing including at least one discrete bearing member having a width taken in said circumferential direction;

said inwardly-facing surface is an inwardly-facing surface of a said discrete bearing member; and

said portion of said fiber optic means is retained by said channel means so as to be disposed approximately in said circumferential direction over at least a part of said width.

15. For a mechanical system of the type including a rotatable shaft and a bearing, wherein said bearing includes an inside bearing surface and wherein said rotatable shaft is in slidable engagement with said inside bearing surface, a method of ascertaining wear of said inside bearing surface which is consequential of said engagement, said method comprising:

providing a fiber optic bundle having a substantially uniform fiber optic thickness, a first fiber optic end, a second fiber optic end and a total fiber optic length between said first fiber optic end and said second fiber optic end, said total fiber length including a partial fiber optic length intermediate said first fiber optic end and said second fiber optic end;

associating said fiber optic bundle with said bearing, said associating including entrenching said partial fiber optic length in said inside bearing surface whereby said partial fiber optic length reaches a substantially uniform depth beneath said inside bearing surface which is at least fifty percent of said fiber optic thickness;

transmitting light through said total fiber optic length from said first fiber optic end to said second fiber optic end; and

comparing the quantity of said transmitted light at said first fiber optic end with the quantity of said transmitted light at said second fiber optic end.

16. A method of ascertaining wear as in claim 15, wherein said bearing includes a lateral bearing surface, and wherein said associating includes:

providing a groove in said inside bearing surface;

providing a bore in said bearing, said bore extending from said lateral bearing surface to said groove;

inletting said fiber optic bundle through said bore;

placing said partial fiber optic length in said groove; and

outletting said fiber optic bundle through said bore.

17. A method of ascertaining wear as in claim 15, wherein said bearing is at least partially made of an elastomeric material, and wherein said associating includes integrally curing said elastomeric material and a portion of said said fiber optic bundle, said portion including said partial fiber optic length.

18. A method of ascertaining wear as in claim 17, wherein said bearing includes a lateral bearing surface, and wherein said associating includes inletting and outletting said fiber optic bundle at said lateral bearing surface.

19. A method of ascertaining wear as in claim 18, wherein said inside bearing surface substantially defines a cylinder, and wherein said associating includes approximately orienting said partial fiber optic length in a circumferential direction of said cylinder.

20. A method of ascertaining wear as in claim 19, wherein said bearing is a stave bearing having a pair of stave retainers and a plurality of staves, each said stave having an inside bearing subsurface, wherein a said stave retainer includes said lateral bearing surface, wherein said inside bearing surface includes each said inside bearing subsurface, and wherein said entrenching includes entrenching in a said inside bearing subsurface.