A MEASURING ARRANGEMENT FOR MONITORING A RAILWAY TRACK

Abstract

The invention relates to a measuring arrangement for monitoring a railway track having rails fastened to sleepers, wherein a fibre optic cable is connected to a measuring device in order to detect a strain acting on a rail. In this, the fibre optic cable is clamped in a detachable manner into at least one rail fastening. In this way, a strain transmitted from the rail via the rail fastening to the sleeper acts directly on the fibre optic cable.

Claims

1. A measuring arrangement for monitoring a railway track having rails fastened to sleepers, wherein a fibre optic cable is connected to a measuring device in order to detect a strain acting on a rail, wherein the fibre optic cable is clamped in a detachable manner into at least one rail fastening.

2. The measuring arrangement according to claim 1, wherein the fibre optic cable is clamped into the rail fastenings of the same rail at two successive sleepers.

3. The measuring arrangement according to claim 1, wherein the fibre optic cable has a loop for length compensation between two clamping points.

4. The measuring arrangement according to claim 1, wherein the fibre optic cable is fastened to the rail between two successive sleepers in a detachable manner by means of a fastening means.

5. The measuring arrangement according to claim 1, wherein the at least one rail fastening includes an intermediate layer, and that the clamped fibre optic cable rests against the intermediate layer.

6. The measuring arrangement according to claim 1, wherein the at least one rail fastening includes a tension clamp, and that the clamped fibre optic cable rests against the tension clamp.

7. The measuring arrangement according to claim 1, wherein the at least one rail fastening includes a lateral guide for lateral support of the rail, and that the clamped fibre optic cable rests against the lateral guide.

8. The measuring arrangement according to claim 7, wherein an angle guide plate is arranged as lateral guide.

9. The measuring arrangement according to claim 7, wherein the at least one rail fastening includes a ribbed base plate, and that ribs extending parallel to the rail are arranged as lateral guides.

10. A method for creating a measuring arrangement according to claim 1, wherein, during new track construction or track renewal, a rail is laid on sleepers by means of a track maintenance machine, that—before, after or during this—the fibre optic cable is reeled off a spool arranged on the track maintenance machine and is positioned at respective clamping points, and that the rail is fastened to the sleepers by means of the rail fastenings while simultaneously clamping the fibre optic cable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will be described below by way of example with reference to the accompanying drawings. There is shown in a schematic manner in:

[0018] FIG. 1 a cross-section of a rail and a rail fastening with a ribbed base plate

[0019] FIG. 2 detail A of FIG. 1 with fibre optic cable in detached state

[0020] FIG. 3 detail A of FIG. 1 with fibre optic cable in clamped state

[0021] FIG. 4 a cross-section of a rail and a rail fastening with angle guide plates

[0022] FIG. 5 a top view of a rail and two sleepers

DESCRIPTION OF THE EMBODIMENTS

[0023] A rail 1 shown in FIG. 1 is fastened in a slightly tilted way to a sleeper 3 by means of a rail fastening 2. For pre-setting an exact angle of inclination, the rail fastening 2 includes a ribbed base plate 4 which is screwed fast to the sleeper 3 by means of screws 5. An intermediate layer 7, commonly made of plastic, is arranged between the rail base 6 and the ribbed base plate 4. For lateral support, the ribbed base plate 4 has ribs 8 extending at either side of the rail 1 in the longitudinal direction of the rail. These ribs 8 have recesses, opening towards the bottom, which serve as counter-support for hook bolts 9 of screwed connections 10. By means of these screwed connections 10, a tension clamp 11 is pressed at each side of the rail 1 to the rail base 6 from above. Such an arrangement is common when using wooden sleepers.

[0024] According to the invention, at least one fibre optic cable 12 is arranged which is clamped in a detachable manner into the rail fastening 2. In this, the mechanical characteristics of the fibre optic cable 12 and the rail fastening 2 are matched to one another. For example, the fibre optic cable 12 has a coating of abrasion-resistant plastic or composite material. Thus, premature mechanical wear of the fibre optic cable 12 is avoided. Optionally, the fibre optic cable 12 is also exchanged in the course of a rail exchange, wherein the additional expense thus occurring is negligible.

[0025] In FIG. 1, several useful positions of the fibre optic cable 12 are indicated. For example, a longitudinal groove 13 for receiving the fibre optic cable 12 is provided in the intermediate layer 7. Alternatively, or additionally, the ribbed base plate 4 has a corresponding longitudinal groove 13. The longitudinal groove 13 may also be provided in the sleeper 3, so that a customary rail fastening 2 can be used without further adaptation. The same goes for a longitudinal groove 13 at the underside of the rail base 6.

[0026] As visible in FIGS. 2 and 3, the longitudinal groove 13 in each case has a depth which is less than the diameter of the fibre optic cable 12 in the detached state. In the clamped state, the fibre optic cable 12 is pressed against surfaces of the rail fastening 2 and, optionally, of the rail 1 or the sleeper 3. As a result, loads and vibrations acting on the rail 1 or the sleeper 3 are transmitted directly to the fibre optic cable 12.

[0027] For precisely registering forces and vibrations in a horizontal direction transversely to the rails, the fibre optic cable 12 is arranged in a longitudinal groove 13 of a rib 8. In the mounted state, the fibre optic cable 12 is here clamped between the rib 8 and a lateral web of the rail base 6. In an advantageous further development, this fibre optic cable 12 is combined with a fibre optic cable 12 under the rail base 6. In this manner, a separate registration and evaluation of the horizontal and the vertical forces and vibrations is possible.

[0028] In FIG. 4, an alternative rail fastening 2 is shown which is normally used with concrete sleepers. In this, the sleeper 3 has relief-like recesses on the upper side for receiving the rail fastening 2. Specifically, an intermediate layer 7 and two angle guide plates 14 of the rail fastening 2 are arranged in these recesses. Here, the intermediate plate 7 forms a damping element between the rail base 6 and the sleeper 3. The angle guide plates 14 serve as lateral guides which fixate the rail base 7 in the horizontal direction transversely to the rail. Additionally, each angle guide plate 14 has a groove 15 in which a tension clamp 11, made of bent round material, is snapped into place. The respective tension clamp 11 is tensioned by means of a rail fastening screw 16, wherein the ends of the tension clamp 11 are pressed against the rail base 6 from above.

[0029] Here also, several useful positions of the fibre optic cable 12 are shown. For example, a longitudinal groove 13 is provided in the intermediate layer 7 or in the sleeper 3 underneath the intermediate layer 7. Also advantageous is the arrangement of the fibre optic cable 12 underneath the respective angle guide plate 14 or underneath the respective tension clamp 11. Forces and vibrations in a horizontal direction transversely to the rail are favourably detected with a fibre optic cable 12 between the angle guide plate 14 and the associated lateral web of the rail base 6. To that end, the corresponding angle guide plate 14 has a lateral longitudinal groove 13. In this variant also, the arrangement of several fibre optic cables 12 may be useful.

[0030] In the top view in FIG. 5, two rail fastenings 2 with a respective ribbed base plate 4 are shown by example. The fibre optic cable 12 is clamped in the respective rail fastening 2 underneath the rail 1. For example, the respective ribbed base plate 4 has a corresponding longitudinal groove 13. In the case of strains, the fibre optic cable 12 is discretely excited at these clamping points 17, so that corresponding discrete measuring results are available in the case of a measuring operation.

[0031] Between the sleepers, the fibre optic cable 12 is arranged in a loop 18. This loop 18 serves as length compensation if the fibre optic cable 12 has to be repaired or positioned in another way. In order to utilize the length compensation of several loops 18, the rail fastenings 2 lying there between are loosened, so that the fibre optic cable 12 can glide through the rail fastenings 2. For example, in the case of welding work on the rail 1, the fibre optic cable 12 is placed at a sufficient distance to the welding location by using the length compensation.

[0032] Favourably provided in the respective sleeper crib between two sleepers 3 is a fastening means 19 by means of which the fibre optic cable 12 is detachably fastened to the rail 1. In the simplest case, this is a clip which is clasped to the rail base 6 and keeps the fibre optic cable 12 in position. In this manner, the fibre optic cable 12 is sufficiently protected in the case of maintenance operations like rail grinding or track tamping. Such fastening means 19 can also be used to omit the detector function of the fibre optic cable 12 in complicated track installations. For example, in the region of a switch, the fibre optic cable 12 is clipped only to a rail 1 without any clamping into the rail fastenings 2.

[0033] One end of the fibre optic cable 12 is connected to a measuring device 20. The latter sends light impulses into at least one fibre of the fibre optic cable 12 and evaluates the resulting reflections. These reflections depend on the mechanical tension in the respective fibre of the fibre optic cable 12. Such mechanical tensions arise when forces act on the fibre optic cable 12, or when the fibre optic cable 12 is set in vibration by concussions or by noise effects. Via evaluable signal patterns, in particular by a discrete characteristic of the measuring signal, it is also possible to localize the force effect or the vibration actuation.

[0034] The method according to the invention for creating the measuring arrangement is explained with reference to the variant in FIG. 5. Serving as an example is a track maintenance operation in which old rails 1 are exchanged for new rails 1 in a continuous working process. In such a rail exchange, the new rails 1 are pre-deposited beside the track. In a first step, the rail fastenings 2 are loosened. A so-called track relaying train is used as track maintenance machine. In a center part, this train has a relaying device which is supported in bridge-like fashion on a front and a rear on-track undercarriage. In this, the front on-track undercarriage travels on the old rails 1, and the rear on-track undercarriage travels already on the new rails 1.

[0035] During forward motion of the machine, the relaying device—using suitable guide elements—lifts the old rails 1 from the sleepers 3 and guides them outward next to the track. Using other guide elements, the new rails are guided from the outside to the inside and laid upon the sleepers 3. In the course of this exchanging procedure, rail fastenings 2 of individual sleepers 3 are exposed. This state is used to place the fibre optic cable 12 at the respective clamping points 17.

[0036] In this, a spool (cable drum) is arranged in the relaying device, from which the fibre optic cable 12 is reeled off during the machine advance. A positioning device guides the fibre optic cable 12 into the exposed longitudinal grooves 13 of the ribbed base plates 4. This takes place either for one rail line only, or a separate fibre optic cable 12 for each rail line is reeled off from an associated spool. Subsequently, the intermediate layers 7 are laid on the ribbed base plates 4 by means of a suitable laying device.

[0037] Only then, the positioning of the new rails 1 between the ribs 8 of the ribbed base plates 4 on the sleepers 3 takes place. In a final work step, the tension clamps 11 are fastened tight by means of the screwed connections 10. During this, the fibre optic cable 12 is also clamped into the corresponding rail fastenings 2.