RAIL MEASURING SYSTEM

• US 20160356661A1
• Filed: 07/18/2016
• Published: 12/08/2016
• Est. Priority Date: 01/21/2014
• Status: Active Grant

• Current Assignee: Thales Management & Services Deutschland GmbH (Thales SA)
• Original Assignee: Thales Deutschland GmbH (Thales SA)
• Inventors: Glueck, Martin, Mueller, Mathias
• Granted Patent: US 10,444,095 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B61K 9/08 Measuring installations for surveying permanent way applications of measuring apparatus or devices for track building purposes E01B35/00; measuring techniques G01
• CPC Class Codes: B61L 23/04 for monitoring the mechanical state of the route
• CPC Class Codes: B61L 23/042 Track changes detection
• CPC Class Codes: B61L 23/047 Track or rail movements
• CPC Class Codes: B61L 25/021 Measuring and recording of train speed
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings
• CPC Class Codes: G01L 1/247 using distributed sensing elements, e.g. microcapsules along a single optical fibre G01L1/242
• CPC Class Codes: G01M 11/085 the optical fiber being on or near the surface of the DUT

Abstract

At least one fiber-optic sensor unit measures a mechanical variable which affects a rail having a certain length and a neutral axis that extends along said length of the rail. The at least one fiber-optic sensor unit is disposed at an angle of 30° to 60°, in particular 45°, relative to the neutral axis or at an angle of −30° to −60°, in particular −45°, relative to the neutral axis. The at least one fiber-optic sensor unit is irradiated with primary light in order to generate a signaling light in a reflection mode or transmission mode. The intensity of the signaling light is sensed. The signaling light is evaluated.

Claims

1. A method of measuring a mechanical variable which acts on a rail with a longitudinal extension using at least one fiber-optic sensor unit, the rail having a neutral axis which extends along the longitudinal extension, the method comprising the steps of:

providing the at least one fiber-optic sensor unit at a positive first angle of 30°

to 60°

relative to the neutral axis or at a negative angle of −

30°

to −

60°

relative to the neutral axis;

irradiating the at least one fiber-optic sensor unit with a primary light for generating a signal light in a reflection mode or a transmission mode;

detecting the intensity of the signal light; and

evaluating the signal light.

2. The method according to claim 1, wherein the step of providing the at least one fiber-optic sensor unit is at the positive angle of 45°

relative to the neutral axis or at the negative angle of −

45°

relative to the neutral axis.

3. The method according to claim 1, wherein the step of evaluating the signal light includes determining the shear deformations of the rail caused by a train running on the rail, wherein the at least one fiber-optic sensor unit is provided approximately at the neutral axis of the rail.

4. The method according to claim 1, wherein the step of evaluating includes counting of the axles that run over the at least one fiber-optic sensor unit.

5. The method according to claim 1, further including the step of providing a second fiber-optic sensor unit at a positive second angle of 30°

to 60°

relative to the neutral axis or at a negative second angle of −

30°

to −

60°

relative to the neutral axis.

6. The method according to claim 5, wherein the positive or negative sign of the second angle differs from the positive or negative sign of the first angle.

7. The method according to claim 1, wherein the step of evaluating the signal light comprises determination of the load on the rail, measurement of the speed, detection of the direction of passing trains, wheel damages of trains on the rail and/or train classification of passing trains.

8. The method according to claim 1, wherein the at least one fiber-optic sensor unit has a converter structure which amplifies the mechanical variable that acts on the at least one fiber-optic sensor unit.

9. A fiber optical sensor unit for detecting a mechanical force acting on a rail, comprising:

an optical fiber;

a fiber Bragg grating provided in the optical fiber which has a Bragg wavelength that depends on the mechanical force;

a converter structure, wherein the converter structure has a signal amplification lever; and

an edge filter for filtering a first part of a signal light.

10. The fiber-optic sensor unit according to claim 9, wherein the edge filter has a filter characteristic line with a nominal slope of between 2% and 7% per nm related to the transmitted intensity or less, wherein a measuring range of axle loads of 200 kg to 50,000 kg that act on the rail is provided.

11. The fiber-optic sensor unit according to claim 10, wherein the converter structure is designed to provide temperature compensation, wherein the thermal expansion coefficient of the converter structure of a converter structure with negative transmission ratio is smaller than the thermal expansion coefficient of the rail or wherein the thermal expansion coefficient of the converter structure of a converter structure with positive transmission ratio is larger than the thermal expansion coefficient of the rail.

12. The fiber-optic sensor unit according to claim 9, wherein the converter structure is designed to provide temperature compensation, wherein the thermal expansion coefficient of the converter structure of a converter structure with negative transmission ratio is smaller than the thermal expansion coefficient of the rail or wherein the thermal expansion coefficient of the converter structure of a converter structure with positive transmission ratio is larger than the thermal expansion coefficient of the rail.

13. A rail measuring system comprising:

a rail with a longitudinal extension and a neutral axis which extends along the longitudinal extension on which rail a mechanical force acts which is generated by a train running thereon; and

at least one fiber-optic sensor unit for detecting the mechanical force that acts on the rail, wherein the at least one fiber-optic sensor unit comprises;

a fiber Bragg grating provided in an optical fiber which has a Bragg wavelength which depends on the mechanical variable,

wherein the at least one fiber-optic sensor unit is mounted to the rail at a positive first angle of 30°

to 60°

relative to the neutral axis or at a negative second angle of −

30°

to −

60°

relative to the neutral axis of the rail.

14. The rail measuring system according to claim 13, wherein the at least one fiber-optic sensor unit is mounted to the rail at the positive angle of 45°

relative to the neutral axis or at the negative angle of −

45°

relative to the neutral axis.

15. The rail measuring system according to claim 13, wherein the at least one fiber-optic sensor unit is mounted approximately at the neutral axis of the rail.

16. The rail measuring system according to claim 13, wherein the at least one fiber-optic sensor unit includes a converter structure, wherein the converter structure has a signal amplification lever and an edge filter for filtering a first part of a signal light, wherein the edge filter has a filter characteristic line with a nominal slope of 8% per nm related to the transmitted intensity or less, wherein a measuring range of axle loads of 200 kg to 50,000 kg that act on the rail is provided.

17. The rail measuring system according to claim 16, wherein the converter structure is designed to provide temperature compensation, wherein the thermal expansion coefficient of the converter structure of a converter structure with negative transmission ratio is smaller than the thermal expansion coefficient of the rail or wherein the thermal expansion coefficient of the converter structure of a converter structure with positive transmission ratio is larger than the thermal expansion coefficient of the rail.

18. The rail measuring system according to claim 13, further including an evaluation unit which is designed for a measuring frequency of 5 kHz, 8 kHz, 10 kHz or more.

19. The rail measuring system according to any claim 13, further comprising:

a broad-band light source for irradiating the at least one fiber-optic sensor unit with a primary light for generating a signal light;

a beam splitter for splitting the signal light into a first part of the signal light and into a second part of the signal light;

a first detector for detecting the first part of the signal light and a second detector for detecting the second part of the signal light.

20. A method for mounting a fiber-optic sensor unit with a fiber Bragg grating to a rail, comprising:

mounting the fiber-optic sensor unit at a positive angle of 30°

to 60°

relative to the neutral axis or at a negative angle of −

30°

to −

60°

relative to the neutral axis of the rail, wherein the fiber-optic sensor unit is mounted approximately at the neutral axis.