Fiber sensor assembly

Abstract

A bearing which includes a bearing ring and rolling elements. The bearing ring includes an outer surface, having a groove around a circumference of the outer surface, wherein the groove is adapted to accommodate a fiber sensor. The bearing further comprises a clamping element, wherein the clamping element retains the fiber sensor with a clamping force acting in a radial direction of the bearing ring such that the fiber sensor intimately engages the bearing ring. Due to the clamping force, relative movement of the fiber sensor can be reduced.

Claims

1. A bearing comprising: a bearing ring supporting a plurality of rolling elements, the bearing ring comprising an outer surface; a groove around a circumference of the outer surface, wherein the groove accommodates a fiber sensor; and a clamping element, wherein the clamping element engages the fiber sensor with a clamping force acting in a radial direction of the bearing ring such that the fiber sensor intimately engages the bearing ring.

2. The bearing according to claim 1, the bearing ring further comprises a channel for accommodating the clamping element, the groove being located within the channel.

3. The bearing according to claim 1, wherein the groove has an entry with a width one of equal to or greater than a diameter of the fiber sensor, wherein the width of the groove decreases with increasing depth, such that a clamping force on the fiber sensor by the clamping element in an axial direction of the bearing ring is obtained.

4. The bearing according to claim 3, wherein at least part of the width of the groove decreases linearly with depth.

5. The bearing according to claim 3, whereby at least part of the width of the groove decreases with depth in a paraboloidal manner.

6. The bearing according to claim 1, wherein the fiber sensor is an optical fiber.

7. The bearing according to claim 6, wherein the optical fiber comprises a fiber Bragg grating (FBG) sensor.

8. The bearing according to claim 1, whereby the clamping element comprises a clamping ring.

9. A method for connecting a fiber sensor to a bearing, the bearing comprising a bearing ring and rolling elements, whereby the bearing ring comprises an outer surface, the method comprising steps of: providing a groove along at least part of a circumference of the outer surface of the bearing ring, the groove having a width dimension parallel to an axial direction of the bearing ring and a depth dimension parallel to a radial direction of the bearing ring, inserting a fiber sensor into at least part of the groove, mechanically clamping the fiber sensor within the groove, such that the fiber sensor intimately engages the bearing ring with a clamping force over that part of the groove in which it is inserted.

10. The method according to claim 9, further comprising a step of: providing a clamping element for clamping the fiber sensor into the groove.

11. The method according to claim 10, the method further comprising a step of: providing a channel around at least part of the circumference of the outer surface of the bearing ring, whereby the groove is provided in the channel and the clamping element is accommodated in the channel.

12. The method according to claim 9, the method further comprising a step of: providing the groove with an entry having a width of one of equal to or greater than a diameter of the fiber sensor, wherein the width of the groove decreases with depth, such that the clamping force on the fiber sensor acts in a radial direction of the fiber sensor.

13. The method according to claim 12, wherein the groove in cross-section comprises one of the group of a V-shape, an isosceles trapezoid and a semi-ellipse or a combination thereof.

14. The method according to claim 9, wherein the fiber sensor is an optical fiber.

15. The method according to claim 14, wherein the fiber sensor comprises a fiber Bragg grating (FBG) sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will be appreciated upon reference to the following drawings of a number of exemplary embodiments, in which:

(2) FIG. 1 shows an axial cross-section of a bearing according to an embodiment of the present invention;

(3) FIG. 2 shows a radial cross-section of the bearing of FIG. 1;

(4) FIG. 3 shows a detail of the bearing of FIG. 1 indicated by III;

(5) FIG. 4 shows an alternative embodiment of the invention in axial cross-section; and

(6) FIG. 5 shows a bearing according to the invention in perspective view with alternative clamping rings.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(7) FIG. 1 shows an axial cross-section of a bearing 1 comprising an inner bearing ring 2 having an inner raceway 5, and an outer bearing ring 3 having an outer raceway 6. In between the inner and outer rings 2, 3, rolling elements 4 are provided such that the inner and outer bearing rings 2, 3 can rotate with respect to each other. The rolling elements 4 are located in between the inner and outer raceways 5, 6.

(8) A groove 7 is provided at an outer surface 8 of the outer bearing ring 3. The groove 7 accommodates a fiber sensor 9, comprising an optical fiber. In its turn, the groove 7 is provided within a channel 12. The channel 12 is shaped as a recess between two sidewalls 10 forming an increase in thickness of the outer bearing ring 3.

(9) The fiber sensor 9 is accommodated in the groove 7 and connected to the outer bearing ring by means of a clamping ring 11. The clamping ring 11 is accommodated in the channel 12. Clamping ring 11 exerts a clamping force CF onto the fiber sensor 9, as shown in FIG. 3.

(10) FIG. 2 shows a radial cross-section of the bearing 1. The clamping ring 11 is provided around a large part of the circumference of the outer bearing ring 3, except for a relatively small portion forming an opening 13, which is used for placing the clamping ring 11 over the fiber sensor 9 and into the channel 12.

(11) The fiber sensor 9 is accommodated within the groove 7, over essentially the full circumference of the outer bearing ring 3 from a first end 14 to a second end 15. The second end 15 extends from the bearing 1 and can be connected to a suitable detector assembly 30.

(12) The bearing 1 is manufactured by providing the groove 7 in the outer surface 8 of the outer bearing ring 3. The groove 7 has a tapered cross-section extending into the outer bearing ring 3, from the outer surface 8. The fiber sensor 9 is put in the groove 7, upon which the clamping ring 11 is snapped over the outer bearing ring 3. In order to maintain the fiber sensor 9 at its location, a temporary fixation can be provided, such as a glue that evaporates or disintegrates during the remainder of the assembly process. When the bearing 1 is ready for use, this temporary fixation should preferably have disappeared, such that a direct contact between the fiber sensor 9 and the groove 7 is established. The fiber sensor 9 comprises an optical fiber with fiber Bragg gratings 19. This is a type of distributed Bragg reflectors constructed in a short segment of the optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength specific dielectric mirror. The fiber Bragg grating is therefore used as an inline wavelength-specific reflector. Operation of such a sensor is generally conventional and will not be discussed further in the present application.

(13) FIG. 3 shows a detail of the bearing 1 of FIG. 1 indicated by III. The tapered shape of the groove 7 is clearly shown. The width of the entry 16 of the groove 7 is larger than the diameter D of the fiber sensor 9, which in turn is wider than a base 21 of the groove 7. Due to the tapered shape, the sidewalls 17 of the groove 7 grip the fiber sensor 9 at its periphery 18. The groove 7 and fiber 9 are dimensioned specifically such that on insertion of the fiber 9 into the groove 7, the inner surface 20 of the clamping ring 11 is tangential to the periphery 18 of the fiber 9. After providing the clamping ring 11, a clamping force CF is exerted onto the fiber sensor 9. Due to the inclined sidewalls 17 of the groove 7, the clamping force CF has an axial component A and a radial component R.

(14) FIG. 4 shows a bearing 101 according to an alternative embodiment of the invention in axial cross-section with an alternative clamping ring 111. Clamping ring 111 is distinguished from that of the first embodiment by a pair of shoulders 112 extending around the inner circumference. As can be seen in FIG. 4, the shoulders 112 serve to determine the degree of clamping of the fiber sensor 9. The fiber sensor 9 is thus partially received in groove 107 and partially received by the recessed inner surface 120 of the clamping ring 111. It will be understood that other shapes of clamping element and channel may be provided to achieve the same effect.

(15) FIG. 5 shows the bearing 1 of FIGS. 1 to 3 in perspective view with a number of different clamping rings. Clamping ring 111 as shown in FIG. 4 is formed to have an opening 113 allowing the ring 111 to be slipped over the outer bearing ring 3 and into the channel 12. Clamping takes place by the inherent spring properties of the ring 111, which is made of spring steel.

(16) Clamping ring 211 is a complete circumferential ring made of elastic material. It can be slipped over the outer bearing ring 3 by stretching and is retained in the channel 12 by its natural resilience.

(17) Clamping ring 311 is of a screw clamp type, having a pair of flanges 314, that can be drawn to each other by a screw 315. It will be understood that the clamping ring 311 and bearing 1 are shown schematically and that in reality, the flanges 314 will be of a size that they fit within the channel 12.

(18) Clamping ring 411 is of a hose clamp type, having a captive screw 415 that engages with thread sections 414 formed along the ring 411.

(19) Clamping ring 511 is of a cable-tie type. It is formed of plastic and has a ratchet element 515 that engages with serrations 514 formed on the inner surface of the ring 511. The skilled person will recognize that many other alternative forms of clamping ring may be implemented.

(20) Thus, the invention has been described by reference to the embodiment discussed above. It will be recognized that this embodiment is susceptible to various modifications and alternative forms well known to those of skill in the art without departing from the spirit and scope of the invention. In particular, it will be understood that although a single groove and fiber sensor has been described, multiple grooves and or multiple fibers could be incorporated. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.