Clamping device for installation on a railway rail of a sensor for monitoring deformations

Abstract

A clamping device (10, 10') for installation on a railway rail (4) of at least one sensor (5) for monitoring deformations of said railway rail (4), comprising a support plate (1) having an outer face (7) and an inner face (8), opposite to the outer face (7), wherein the outer face (7) is suitable for the operative connection of at least a portion of the at least one sensor (5). The clamping device (10, 10') further comprises a magnetic clamping element (20) comprising at least a first magnet (2) and suitable for being coupled to the inner face (8) of the support plate (1) so as to form a magnetic plate group (9) suitable for magnetic clamping to a portion (4') of the railway rail (4). The clamping device (10, 10') further comprises a coating (3) suitable for being coupled to the magnetic plate group (9) on the side of the magnetic clamping element (20), so that at least a portion of said coating (3) is interposed between the magnetic plate group (9) and the portion (4') of the railway rail (4), when the magnetic plate group (9) is magnetically coupled to said portion (4') of the railway rail (4).

Description

[0001] The present invention pertains to the field of apparatuses for monitoring railway infrastructures, such as railway rails or railway tracks.

[0002] In particular, the subject of the present invention is a clamping device for installation on a railway rail of at least one sensor for monitoring deformations of the railway rail.

[0003] Moreover, the subject of the present invention is an apparatus for monitoring deformations of a railway rail, a railway rail on which such apparatus is installed, a kit for the implementation of such apparatus, and a method of installing such apparatus on a railway rail.

[0004] In the field, numerous examples of apparatuses for monitoring railway infrastructures and clamping devices for installation on a railway rail of sensors for monitoring the railway rail itself are known.

[0005] Typically, the presence of a fastening system to the railway track sleepers, combined with the presence of ballast on the railway track, contributes to the stability of the railway rail, preventing deformations and / or movements that would compromise its stability and safety.

[0006] In general, deformations of a railway rail are caused by the presence of external forces such as frictional forces, generated by the passage of railway vehicles on the rail, and / or by reaction forces to thermal expansions, caused by temperature gradients, for example between the inside and the outside of a tunnel.

[0007] Further external forces may be due to a different type of ballast along the track, a different type of fastening system to the sleepers of the track, or the presence of railway switches along the track.

[0008] Generally, sensors are consequently used to monitor the deformations of the rail, and eventually allow for intervention so that it remains as stable as possible.

[0009] Typically, known railway rail deformation monitoring apparatuses provide an indirect measurement of the deformation (D) of a railway rail by measuring the displacements of its two ends (S1) and (S2) relative to its length (L), through the following expression: D = S 1 − S 2 / L .

[0010] Disadvantageously, this type of indirect deformation measurement of the rail does not allow the measurement of local deformations and is therefore advisable only in the presence of homogeneous railway rails.

[0011] Other known railway rail deformation monitoring apparatuses provide for the use of deformation sensors, for example sensors such as Fiber Bragg Grating (FBG) type optical fiber strain gauges.

[0012] Typically, FBG-type optical fiber sensors consist of optical fiber elements, also known as Bragg gratings, which have bands of material with different refractive indices, arranged in sequence. These bands act as a filter for a specific wavelength of the light signal passing through the transmission medium. When the optical fiber filament of the strain gauge, into which the Bragg grating is inserted, undergoes a change in length as a result of a relative movement between two points of a railway rail, the wavelength of the light signal filtered by the fiber also changes.

[0013] The variation of the wavelength of the light signal filtered by the fiber allows for optical measurement, through a sensor that analyses the wavelength of the signal absorbed by the grating, of the mechanical deformations of the portion of the railway rail, advantageously exploiting the expansion induced on the fiber filament of the strain gauge fixed to the railway rail itself.

[0014] Generally, an FBG-type optical fiber strain gauge is arranged inside a body placed between two terminations, each adapted to be stabilised and fixed to the railway rail.

[0015] Typically, monitoring apparatuses based on sensors such as FBG optical fiber strain gauges consist of an FBG sensor fixed to a support connectable to the railway rail.

[0016] This support is generally coupled to the railway rail by welding, screwing, bolting or gluing.

[0017] Deformations of the rail are generally recorded by the FBG sensors and transferred to appropriate data storage systems, where they are processed according to structural monitoring techniques, in order to obtain information about the railway vehicle passing over the rail or about the railway rail itself.

[0018] In other words, the data detected by the FBG sensors can be used by a processor and correlated to the deformations of the railway rail.

[0019] A typical issue of this embodiment, however, consists in the fact that it requires a complex and costly preparation procedure, both in terms of time and economics. Indeed, often the roughness of the surface of the railway rail does not allow welding of the support with the FBG sensor unless properly pretreated.

[0020] Moreover, this embodiment does not allow for a simple and immediate removal of the monitoring apparatus from the railway rail, which is however necessary to better carry out maintenance of the railway rail itself.

[0021] Therefore, there is still a strong need to be able to remove and reinstall deformation monitoring apparatuses from the railway rail itself, in a simple and immediate manner, so as to allow easier maintenance of the railway infrastructure.

[0022] The object of the present invention is to provide a clamping device for installation on a railway rail of at least one sensor for monitoring deformations of said railway rail, capable of overcoming the drawbacks of the prior art mentioned above.

[0023] Said object is achieved by means of a clamping device in accordance with appended claim 1. Said object is further achieved by means of an apparatus for monitoring deformations of a railway rail, a railway rail on which such apparatus is installed, a kit for the implementation of such apparatus, and a method of installing such apparatus on a railway rail.

[0024] The dependent claims describe preferred embodiments, involving further advantageous aspects of the invention.

[0025] The characteristics and advantages of the clamping device according to the invention will nevertheless become apparent from the following description of preferred embodiments thereof, given by way of example and not limitation, with reference to the accompanying figures, in which: Figure 1 is a perspective view of a clamping device according to the present invention, in one embodiment; Figure 1a is a cross-section of the clamping device of figure 1; Figure 2 is an exploded perspective view of the clamping device of figure 1; Figure 3 is a cross-section of the clamping device of figure 1, when it is coupled to a railway rail; Figure 4 is a perspective view of the apparatus for monitoring deformations of a railway rail according to the present invention, when it is coupled to a railway rail, in one embodiment; Figure 5 is a block diagram of the method of installing on a railway rail the apparatus of figure 4, in one embodiment.

[0026] The reference numerals listed below are also shown in the aforementioned accompanying figures.

[0027] In the continuation of the present disclosure, all directional references (for example, upper, lower, upward, downward, left, right, to the left, to the right, at the top, at the bottom, above, below, vertical, horizontal, clockwise and counterclockwise) are used solely for identification purposes to assist the reader in understanding the embodiments described and do not create limitations, in particular as regards the position, orientation or use of the embodiments described.

[0028] Moreover, the references of connection (for example, fixed, coupled, connected and the like) must be interpreted in a broad sense and may include intermediate elements between a connection of elements and a relative movement between elements.

[0029] Therefore, the references of connection do not necessarily imply that two elements are directly connected and in a fixed relationship with one another.

[0030] In said drawings, 10, 10' denotes a clamping device according to the invention as a whole.

[0031] By "clamping" is meant a type of connection between two members, used particularly for connections that can be easily and immediately released.

[0032] The clamping device 10, 10' for installation on a railway rail 4 of at least one sensor 5 for monitoring deformations of said railway rail 4 according to the present invention comprises a support plate 1.

[0033] In a general embodiment, the support plate 1 has an outer face 7. Said support plate 1 has an inner face 8, opposite to the outer face 7. The outer face 7 of the support plate 1 is suitable for the operative connection of at least a portion of the at least one sensor 5.

[0034] Preferably, the support plate 1 is made of ferromagnetic material, for example ferromagnetic stainless steel.

[0035] The clamping device 10, 10' further comprises a magnetic clamping element 20, which comprises at least a first magnet 2.

[0036] The magnetic clamping element 20 is suitable for being coupled to the inner face 8 of the support plate 1 so as to form a magnetic plate group 9. Said magnetic plate group 9 is suitable for magnetic clamping to a portion 4' of the railway rail 4.

[0037] In one embodiment, the coupling between the support plate 1 and the magnetic clamping element 20 takes place by gluing.

[0038] In a different embodiment, the magnetic clamping element 20 is coupled to the support plate 1 by magnetic coupling.

[0039] The clamping device 10, 10' further comprises a coating 3. Said coating 3 is suitable for being coupled to the magnetic plate group 9 on the side of the magnetic clamping element 20, so that at least a portion of said coating 3 is interposed between the magnetic plate group 9 and the portion 4' of the railway rail 4, when the magnetic plate group 9 is magnetically coupled to said portion 4' of the railway rail 4.

[0040] In one embodiment, the coating 3 is in the form of a sheet.

[0041] In another embodiment, the coating 3 is suitable for being wrapped around the magnetic plate group 9.

[0042] Preferably, the coating 3 is made of a conductive elastomeric material, for example metal rubber.

[0043] In one embodiment, the coupling between the coating 3 and the magnetic plate group 9 occurs by gluing.

[0044] In a different embodiment, the coating 3 is magnetically coupled to the magnetic plate group 9.

[0045] In one embodiment, the magnetic plate group 9 is suitable for magnetic clamping to the head of the railway rail 4. By "head" of a railway rail is meant the upper part of the rail itself, which supports the weight of the train.

[0046] In another embodiment, illustrated in the drawings, the magnetic plate group 9 is suitable for magnetic clamping to the web of the railway rail 4. By "web" of a railway rail is meant the lower part of the rail itself, which extends from the base to the head. In other words, the web is the vertical portion of the rail located under the head, which serves to ensure the stability of the rail itself.

[0047] In yet another embodiment, the magnetic plate group 9 is suitable for magnetic clamping to the base of the railway rail 4. By "base" of a railway rail is meant the bottom part of the rail itself, which rests on and is anchored to the sleeper of the track.

[0048] In one embodiment, the magnetic clamping element 20 also comprises a second magnet 2'. In this embodiment, the first magnet 2 and the second magnet 2' extend parallel to each other.

[0049] Preferably, the at least one magnet 2, 2' is a permanent magnet. In other embodiments, the at least one magnet 2, 2' may be an electromagnet.

[0050] For example, the at least one magnet 2, 2' is a neodymium magnet.

[0051] In one embodiment, each magnet 2, 2' is in the form of a bar having a main extension parallel to the extension direction X of the railway rail 4. In this embodiment, each magnet 2, 2' has the magnetic poles 8, 8', 8'', 8‴ arranged so that the magnetic moment of each magnet 2, 2' is directed perpendicular to the extension direction X of the railway rail 4.

[0052] In one embodiment, the magnetic poles 8, 8' of the first magnet 2 and the magnetic poles 8'', 8‴ of the second magnet 2' are arranged so that the respective magnetic moments have the same direction and opposite orientation.

[0053] In other words, the magnetic poles 8, 8', 8'', 8‴ of the first magnet 2 and of the second magnet 2' are positioned so that the magnetic north pole 8 of the first magnet 2 is positioned near the magnetic south pole 8‴ of the second magnet 2', and the magnetic south pole 8' of the first magnet 2 is positioned near the magnetic north pole 8'' of the second magnet 2'.

[0054] According to a further aspect, the subject of the present invention is also an apparatus 30 for monitoring deformations of a railway rail 4.

[0055] Said apparatus comprises at least one clamping device 10, 10' as described above. The apparatus further comprises at least one sensor 5 for monitoring deformations of the railway rail 4. The sensor 5 is operatively connectable to the at least one clamping device 10, 10', so as to monitor deformations of the railway rail 4.

[0056] In one embodiment illustrated in figure 4, the apparatus 30 for monitoring deformations of a railway rail 4 comprises a first clamping device 10 and a second clamping device 10', separate and spaced from the first clamping device 10 in the extension direction X of the railway rail.

[0057] In this embodiment, the sensor 5 for monitoring deformations of the railway rail 4 is operatively connected to the first clamping device 10 and to the second clamping device 10'.

[0058] In one embodiment, the sensor 5 is operatively connected to the at least one clamping device 10, 10' by welding or bolting.

[0059] Preferably, the sensor 5 for monitoring deformations of the railway rail 4 is a fiber optic sensor of the FBG (Fiber Bragg Grating) type.

[0060] According to a further aspect, the subject of the present invention is also a railway rail 4 on which an apparatus 30 for monitoring deformations of said rail is installed.

[0061] According to yet another aspect, the subject of the present invention is also a kit for the implementation of an apparatus 30 for monitoring deformations of a railway rail 4.

[0062] Said kit comprises at least one support plate 1, a magnetic clamping element 20, at least one coating 3, at least one sensor 5, gluing means, for example epoxy adhesive, a plurality of fastening means, for example spacers and / or screws and / or bolts.

[0063] According to a further aspect, the subject of the present invention is also a method of installing on a railway rail 4 an apparatus 30 for monitoring deformations of said railway rail 4, which uses the kit defined above.

[0064] With reference to the flow diagram of figure 5, the method therefore provides for supplying the kit for the implementation of the apparatus 30 for monitoring deformations of the railway rail 4 (step a).

[0065] The method provides for distributing the gluing means on the inner face 8 of the support plate 1 (step b), and for coupling the magnetic clamping element 20 to the inner face 8 of the support plate 1, thereby defining a magnetic plate group 9 (step c).

[0066] The gluing means are distributed on the magnetic plate group 9 on the side of the magnetic clamping element 20 (step d), so as to couple the coating 3 to the magnetic plate group 9 on the side of the magnetic clamping element 20, thereby defining a clamping device 10, 10' (step e).

[0067] These steps are then repeated for each support plate 1 (step f).

[0068] Subsequently, at least one sensor 5 is operatively connected to the at least one clamping device 10, 10' (step g), thus defining an apparatus 30 for monitoring deformations of the railway rail 4.

[0069] Said apparatus 30 may then be installed on the railway rail 4 (step h).

[0070] Extremely advantageously, the clamping device 10, 10', compared to traditional fastening means, allows for the rapid removal and re-installation of the monitoring apparatus 30, facilitating the maintenance of the railway rail 4.

[0071] Furthermore, the clamping device 10, 10', compared to traditional fastening means, does not require treatment or machining operations on the contact surface of the railway rail 4 to proceed with the installation of the monitoring apparatus 30.

[0072] Advantageously, the presence of a support plate 1 provides solidity to the clamping device 10, 10'.

[0073] Advantageously, the orientation of the at least one magnet 2, 2' allows the magnetic plate group 9 to be magnetically coupled to the railway rail 4 through a magnetic force directed perpendicularly to the extension direction X of the railway rail 4.

[0074] Extremely advantageously, the presence of a coating 3 increases the friction between the surface of the magnetic plate group 9 and the surface of the railway rail 4, absorbing the deformations of the roughness of the surface of the railway rail 4. This allows the clamping device 10, 10' to have a better grip on the railway rail 4 and to be more resistant to detachment caused by the vibrations to which the railway rail 4 is subjected due to the passage of railway vehicles.

[0075] Advantageously, the presence of a coating 3 made of conductive elastomeric material, for example metal rubber, offers a dual advantage: on the one hand, it is a material that increases the friction between the clamping device 10, 10' and the rail 4, and on the other hand, it does not generate air gaps, that is, it does not create interruptions in the magnetic field lines, which from the clamping device 10, 10' close on the rail 4.

[0076] Advantageously, the presence of a coating 3 made of conductive elastomeric material, for example metal rubber, reinforces the magnetic field lines and consequently the magnetic attraction force between the clamping device 10, 10' and the railway rail 4.

[0077] Advantageously, the presence of a coating 3 made of conductive elastomeric material, for example metal rubber, significantly increases the holding both against sliding and detachment, improving resistance to vibrations and allowing the various components to remain firmly anchored in the original position without undergoing damage or unwanted movements that would compromise the effectiveness of the sensor.

[0078] Furthermore, the presence of a coating 3 made of conductive elastomeric material, for example metal rubber, allows for the reduction of micro-sliding of the sensor 5 on the railway rail 4 due to vibrations, increasing the effectiveness of the sensor 5, absorbing the deformations that occur beneath it when the clamping device 10, 10' is coupled to the railway rail 4, and reducing the wear of the clamping device 10, 10'.

[0079] In other words, the configuration and structure of the clamping device 10, 10' allows the formation of magnetic field lines which, once the clamping device 10, 10' is applied to the railway rail 4, close, maximising the magnetic attraction force between the clamping device 10, 10' itself and the railway rail 4.

[0080] Furthermore, the arrangement of the magnetic poles 8, 8', 8", 8‴ of the magnets 2, 2' allows the creation of magnetic field lines that close on the railway rail 4.

[0081] Advantageously, the assembly of magnets with opposite polarity constitutes a magnetic circuit designed to focus the magnetic flux. To ensure the stability of the clamping device, especially against vibrations induced by the rail, the shear force (tangential force) is maximised. This shear force is directly proportional to the coefficient of friction between the surfaces and to the perpendicular force (magnetic attraction force). To maximise this perpendicular force, the magnetic field flux on the friction surfaces is maximised; any dispersion of the magnetic flux outside said surfaces constitutes a waste, forcing the use of more powerful and consequently heavier magnets. Heavier magnets are more susceptible to being dislodged by the significant vibrations of the rail. The elastopolymeric element, intrinsically ferromagnetic (magnetic conductor), allows for the confinement of the magnetic flux in the magnetic circuit, maximising the flux passing through it and, consequently, allowing a reduction in the weight of the required magnets. Furthermore, the metal rubber nature of the elastopolymeric element is such that, under the influence of the magnetic force, it undergoes compression, reducing its thickness and further increasing the magnetic attraction force due to the decrease in distance. Finally, the elastoplastic nature of the material contributes to absorbing and compensating for any imperfections and surface roughness of the rail, ensuring a stable coupling of the clamping device.

[0082] Advantageously, the coupling by gluing between the support plate 1 and the magnetic clamping element 9 makes it possible to obtain a more solid and compact clamping device 10, 10'.

[0083] Furthermore, the coupling by gluing between the coating 3 and the magnetic plate group 9 makes it possible to obtain a more solid and compact clamping device 10, 10'.

[0084] Still further, the support plate 1 made of ferromagnetic material, for example ferromagnetic stainless steel, makes it possible to increase the magnetic attraction force between the clamping device 10, 10' and the rail 4.

[0085] Still further, the presence of two magnets 2, 2' makes it possible to increase the magnetic attraction force between the clamping device 10, 10' and the rail 4.

[0086] To the embodiments of the clamping device according to the invention, a person skilled in the art, in order to meet contingent requirements, may make modifications, adaptations, and replacements of elements with other functionally equivalent elements, without departing from the scope of the following claims. Each of the characteristics described as belonging to a possible embodiment may be implemented independently of the other described embodiments.

Claims

1. A clamping device (10, 10') for installing on a railway rail (4) at least one sensor (5) for monitoring deformations of said railway rail (4), comprising: - a support plate (1), said support plate (1) having an outer face (7) and an inner face (8), opposite to the outer face (7), wherein the outer face (7) is suitable for the operating connection of at least one portion of the at least one sensor (5); - a magnetic clamping element (20) comprising at least a first magnet (2) and suitable for being coupled to the inner face (8) of the support plate (1) so as to form a magnetic plate group (9) suitable for the magnetic clamping to a portion (4') of the railway rail (4) ; - a coating (3) suitable for being coupled to said magnetic plate group (9) on the side of the magnetic clamping element (20), so that at least one portion of said coating (3) is interposed between the magnetic plate group (9) and the portion (4') of the railway rail (4), when the magnetic plate group (9) is magnetically coupled to said portion (4') of the railway rail (4).

2. Clamping device according to claim 1, wherein the coating (3) is made of a conductive elastomeric material, for example metal rubber.

3. Clamping device according to any one of the preceding claims, wherein the coupling between the support plate (1) and the magnetic clamping element (20) occurs by gluing.

4. Clamping device according to any one of the preceding claims, wherein the coupling between the coating (3) and the magnetic plate group (9) occurs by gluing.

5. Clamping device according to any one of the preceding claims, wherein the support plate (1) is made of a ferromagnetic material, for example ferromagnetic stainless steel.

6. Clamping device according to any one of the preceding claims, wherein the magnetic clamping element (20) further comprises a second magnet (2'), and wherein the first magnet (2) and the second magnet (2') extend parallel to each other.

7. Clamping device according to the preceding claim, wherein each magnet (2, 2') is a neodymium magnet.

8. Clamping device according to any one of claims 6 or 7, wherein each magnet (2, 2') is in the form of a bar having a main extension parallel to the extension direction (X) of the railway rail (4), and wherein each magnet (2, 2') has the magnetic poles (8, 8', 8", 8‴) arranged so that the magnetic moment of each magnet (2, 2') is directed perpendicular to the extension direction (X) of the railway rail (4).

9. Device according to claim 8, wherein the magnetic poles (8, 8') of the first magnet (2) and the magnetic poles (8'', 8‴') of the second magnet (2') are arranged so that the respective magnetic moments have the same direction but opposite orientation.

10. An apparatus (30) for monitoring deformations of a railway rail (4), comprising: - at least one clamping device (10, 10') according to any one of the preceding claims; - at least one sensor (5) for monitoring deformations of the railway rail (4), said sensor (5) being operatively connectable to the at least one clamping device (10, 10'), so as to monitor deformations of the railway rail (4).

11. Apparatus according to the preceding claim, comprising a first clamping device (10) and a second clamping device (10'), the sensor (5) for monitoring deformations of the railway rail (4) being operatively connected to the first clamping device (10) and the second clamping device (10').

12. Apparatus according to claim 10 or 11, wherein the sensor (5) is operatively connected to the at least one clamping device (10, 10') by welding or bolting.

13. Apparatus according to any one of claims 10 to 12, wherein the sensor (5) for monitoring deformations of the railway rail (4) is a fiber optic sensor of the Fiber Bragg Grating (FBG) type.

14. A railway rail (4) on which an apparatus (30) for monitoring deformations of said railway rail (4) according to any one of claims 10 to 13 is installed.

15. A kit for obtaining an apparatus (30) for monitoring deformations of a railway rail (4) according to any one of claims 10 to 13, said kit comprising: - at least one support plate (1); - a magnetic clamping element (20); - at least one coating (3); - at least one sensor (5); - gluing means, for example epoxy adhesive; - a plurality of fastening means, for example spacers and / or screws and / or bolts.

16. A method of installing, on a railway rail (4), an apparatus (30) for monitoring deformations of said railway rail (4), said method comprising the steps of: a) providing a kit for obtaining the apparatus (30) for monitoring deformations of the railway rail (4) according to claim 15; b) distributing the gluing means on the inner face (8) of the support plate (1); c) coupling the magnetic clamping element (20) to the inner face (8) of the support plate (1), thus defining a magnetic plate group (9); d) distributing the gluing means on the magnetic plate group (9) on the side of the magnetic clamping element (20) ; e) coupling the coating (3) to the magnetic plate group (9) on the side of the magnetic clamping element (20), thus defining a clamping device (10, 10'); f) repeating steps b) to e) a plurality of times corresponding to the plurality of support plates (1); g) operatively connecting the at least one sensor (5) to the at least one clamping device (10, 10'), thus defining an apparatus (30) for monitoring deformations of the railway rail (4); h) installing the apparatus (30) defined in step g) on the railway rail (4).

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