Mounting element, sensor unit with a sensor and a mounting element, sensor unit and method for mounting a sensor unit

Abstract

The invention relates to a holding device (10) for a sensor (12) that can be attached to a structure (3) by means of a light-curing adhesive (24). The light-curing adhesive (24) is cured within the cavities (20) provided for receiving the light-curing adhesive (24) by direct and / or indirect illumination. The invention further relates to a sensor unit (2) with a sensor (12) and a holding device (10), an arrangement (1) with a sensor unit (2) and a structure (3), and a method for providing an arrangement (1).

Description

Background of the invention

[0001] The invention relates to a fastening element for attaching a sensor to a structure to be monitored, in particular a rail, a sensor unit with such a fastening element, a sensor arrangement for attaching the sensor unit to a structure to be monitored, and a method for arranging the sensor unit.

[0002] Fasteners that are attached using adhesive materials are already known in the art and serve to attach components, especially sensors, to structures. A typical application is in rail monitoring elements. The components of the rail monitoring element, especially sensors for measuring forces acting on the rail, can be attached to the rail without weakening the structure, for example, by drilling holes.

[0003] Fastening elements for attaching photovoltaic modules to structures using elastic adhesives are known from [1] and [2]. Although elastic adhesives exhibit high weather and aging resistance, they also compensate for expansions and movements of the structure and are therefore not suitable for attaching sensors that are intended to measure forces acting on the structure.

[0004] Therefore, mounting elements for rail monitoring devices with sensors are attached using adhesives that exhibit the highest possible rigidity after curing. Thermal bonding methods are predominantly used, particularly when attaching mounting elements to rails.

[0005] From [4] a method for mounting a rail monitoring element using a heat-activated film is known. The connection is made by inductively heating the rail. However, this requires a considerable energy input in the form of heat, which, in addition to the high energy costs, necessitates equipment capable of supplying the required energy even in remote and difficult-to-access track sections. The heavy and bulky equipment required for inductive heating must be transported to the installation site by skilled personnel, ultimately resulting in significant logistical challenges.

[0006] From [3] the applicant discloses a rail monitoring element which is attached to a rail by means of a thermally activatable adhesive. The rail monitoring element is pressed against the rail and the adhesive is heated by a hot wire located in the adhesive layer to create the adhesive bond. In this method, however, the heat input for curing the adhesive only occurs at specific points. Object of the invention

[0007] The object of the invention is to provide a fastening element and a sensor unit with such a fastening element which is inexpensive to manufacture and, moreover, can be attached to a structure to be monitored in a cost-effective manner and with little effort. Description of the invention

[0008] This problem is solved according to the invention by a fastening element according to claim 1, a sensor unit according to claim 11, a sensor arrangement according to claim 13 and a method according to claim 14.

[0009] The fastening element according to the invention comprises a base support element, a sealing frame for sealing the base support element against the structure, a cavity for receiving a light-curing adhesive, wherein the cavity is bounded on one side by the base support element and circumferentially by the sealing frame, and at least one light-emitting element for coupling light rays into the cavity. Furthermore, the fastening element may comprise additional elements, in particular a protective cover.

[0010] The base support element serves to mount a component, in particular a sensor, and is advantageously designed in the form of a rectangular plate. Other shapes may result from the sensor to be attached and the surface of the structure to which the mounting element is to be fastened. In particular, round and / or polygonal shapes are conceivable. The base support element is designed for mounting on a structure to be monitored. In general, the mounting element can be mounted on any surface. The following section describes, by way of example, the mounting element in the application area of ​​rail monitoring elements, where the structures to be monitored are, in particular, rails and axles. This list is not exhaustive.

[0011] When mounted on a rail, the fastening element is preferably positioned in the vertical section of the rail profile (rail neck). In the preferred installation position, the base support element is thus positioned parallel to the rail. The base support element is spaced away from the rail in at least a partial section. In other words, a gap is created between the base support element and the rail.

[0012] The sealing frame is attached to the base support element, either detachably or permanently, and maintains a distance between the base support element and the structure. The sealing frame seals the gap between the base support element and the rail, particularly completely, and together with the base support element forms a cavity. The sealing frame can be flexible, particularly made of an elastomer, preferably silicone, and / or rigid. The sealing frame can be integrally formed with the base support element. A flexible design is particularly advantageous with regard to ensuring the sealing frame has minimal gaps against the surface of the structure in the mounting area. This improves the sealing effect of the sealing frame.

[0013] The cavity is formed between the base support element and the structure and is bounded circumferentially by the sealing frame. In other words, the cavity is predominantly, in particular completely, closed on the side facing the base support element and predominantly, in particular completely, open on the side facing the structure.

[0014] The cavity is designed to receive a light-curing adhesive. A light-curing adhesive is an adhesive bonding agent that hardens under the influence of light, especially ultraviolet light (UV light).

[0015] The mounting element has a light-emitting surface for coupling light into the cavity. This light-emitting surface forms an interface with the cavity. In other words, the mounting element has a surface through which light is emitted into the cavity. Examples of light-emitting surfaces include a translucent LED housing, particularly an LED lens, the cavity-facing surface of a transparent layer containing the light source, or the surface of a light-guiding film or plate, although this list is not exhaustive. The incident light can be emitted directly at the light-emitting surface and / or guided to the light-emitting surface via light-guiding structures (light-guiding film / plate).By introducing light into the cavity when arranging the fastener on the structure, the curing of the light-curing adhesive and thus the attachment of the fastener to the structure is enabled.

[0016] A preferred embodiment includes at least one through-hole for introducing the light-curing adhesive into the cavity. This through-hole can be formed in the base support element and / or in the sealing frame and connects the cavity to the surroundings of the fastening element. The through-hole can, in particular, be in the form of a gap in the sealing frame. The through-hole advantageously has a clear width of 1–30 millimeters, particularly 2–20 millimeters, and most preferably 5–10 millimeters. This allows the adhesive to be easily injected into the cavity using a filling device, especially a cartridge gun.

[0017] A particularly preferred development is one in which the fastening element has at least one additional through-hole and / or a filling indicator. An additional through-hole allows air to escape from the cavity particularly easily during the adhesive filling process, especially when the sealing frame is in close contact with the structure. Furthermore, an additional through-hole allows for an assessment of the cavity's filling level, as excess adhesive can ooze out of the additional through-hole after the cavity is largely, and especially completely, filled. Alternatively or additionally, a filling indicator can be designed in the form of a semi-transparent area, particularly a clear viewing window, in the base support element and / or the sealing frame, and at least allow for an assessment of the cavity's filling level.

[0018] A further preferred embodiment includes at least one light source, in particular a light-emitting diode, for direct or indirect, at least partial, and in particular complete, illumination of the cavity. The light source is oriented with respect to the light-emitting surface such that the light emission occurs predominantly, and in particular completely, into the cavity. In other words, the illuminating effect of the light source is directed directly and / or indirectly, in particular via a light-guiding film or a light-guiding plate, into the cavity. The light emission is directed, in particular, from the base support element towards the side of the cavity opposite the base support element.

[0019] In another preferred embodiment, the fastening element has a plurality of light sources that are spaced apart from one another, in particular equidistant. This enables particularly uniform and complete illumination of the cavity.

[0020] A preferred embodiment is one in which the light sources are arranged within the cavity of the fastening element. The light sources themselves can constitute the light-emitting surface. In this embodiment, the cavity is directly illuminated by the light sources. The arrangement of the light sources in a plane, directed towards the cavity, particularly on the base support element, is especially advantageous. A particularly uniform illumination is achieved by arranging the light sources in a plane within the cavity. The light-emitting surface is positioned between the cavity and the light source and protects the light source from direct contact with the light-curing adhesive. The light-emitting surface can be designed to diffuse light, particularly preferably to diffuse light, in order to maximize the illumination area of ​​the light source.This ensures that the light-curing adhesive cures particularly evenly and completely. After the adhesive has cured, the light sources remain within the cavity as so-called "lost elements".

[0021] A further preferred embodiment of the fastening element comprises a base support element with a transparent layer in which the light source is arranged. The light source is oriented in the transparent layer to transmit light directly into the cavity. The transparent layer, together with the light source, forms a "luminescent layer," so that the cavity is bounded by a flat surface. This facilitates filling the cavity.

[0022] A preferred design is a further development of the fastening element in which the light source is configured to emit UV light. This promotes particularly rapid curing when using UV-curing adhesives.

[0023] A particularly preferred embodiment includes at least one light-guiding element for connecting the light source to the light-emitting surface. This allows the light source to be positioned at a distance from the cavity. In other words, the light source can be located outside the cavity on the mounting element. The light source emits light into a light-guiding element, particularly a light-guiding film, which has at least one light-exit area directed into the cavity. In other words, the cavity is illuminated indirectly. The light-guiding element, especially the light-guiding film, has the light-emitting surface in the light-exit area, thus enabling uniform light emission. This improves the light distribution within the cavity.

[0024] In a particularly preferred embodiment of the fastening element, the light source is arranged circumferentially on and / or within the sealing frame. The sealing frame can be at least partially, and in particular completely, transparent. The sealing frame can also include the light-emitting surface. Alternatively, the light can be coupled through the transparent frame into a light-guiding element adjacent to the frame. This allows the base support element to remain unchanged, which has a particularly advantageous effect on existing manufacturing processes.

[0025] Alternatively or additionally, the sealing frame can have through-holes designed for the placement of the light source. In a particularly advantageous embodiment, the light source is arranged in and / or on at least one through-hole designed for filling the cavity after the cavity has been filled.

[0026] In a preferred embodiment of the fastening element, the sealing frame has an adhesive, in particular a resin or an adhesive tape, on its side facing the structure. This allows for temporary attachment of the fastening element to the structure and simplifies the injection of the adhesive and the curing process.

[0027] A particularly preferred embodiment of the fastening element is one in which the light source is detachably and / or loosely arranged on the base support element and / or the sealing frame. In this embodiment, the light source can be advantageously attached to the fastening element for the duration of the adhesive curing and then removed. This eliminates any "lost elements" on or in the fastening element, and the light source can be particularly advantageously reused.

[0028] Alternatively or additionally, the light source can be positioned next to the mounting element and connected to it, particularly the cavity, only via at least one light-guiding element, particularly for a limited time. In this case, a first light-guiding element can be arranged on the light source and a second light-guiding element on the mounting element, with the first light-guiding element being positioned on the second light-guiding element for the duration of the cavity illumination.

[0029] A preferred embodiment further includes a protective cover on the fastening element, particularly on the base support element and / or the sealing frame. The protective cover can be detachably and / or permanently attached to the fastening element. In particular, a snap-in device and / or a screw-in device can be provided for attaching the protective cover to the fastening element. A protective cover effectively protects the fastening element and any components attached to it from unauthorized access and from weather and / or environmental influences.

[0030] The sensor unit according to the invention comprises a mounting element and a sensor. The sensor can be detachably or permanently attached to the mounting element. The sensor is located on the side of the base support element facing away from the cavity. This particularly advantageously allows the sensor to be attached to the mounting element after the mounting element has been attached to the structure. However, it is also conceivable that the sensor is already attached to the base support element when the mounting element is attached to the structure.

[0031] The mounting element is designed to accommodate a wide variety of sensors. A sensor is any type of measuring probe and / or detector used to measure a physical or chemical property. Examples include, but are not limited to, temperature sensors, strain gauges, humidity sensors, pressure sensors, and ion strength sensors.

[0032] In a preferred further development of the sensor unit, the sensor is a strain sensor, preferably a rail monitoring element with an optical fiber with fiber Bragg grating.

[0033] The sensor arrangement according to the invention comprises a sensor unit and a structure to be monitored. The sensor unit is arranged on the structure such that a light-cured adhesive introduced into the cavity forms a connection between the base support element and the structure. In other words, when the sensor unit is arranged on the structure, the cavity of the fastening element is predominantly, and in particular completely, filled with light-cured adhesive.

[0034] The inventive method for attaching a sensor unit to the structure comprises the following process steps: a) Applying the sensor unit to the structure; b) Introducing the light-curing adhesive into the cavity of the sensor unit; c) Introducing light into the cavity for the purpose of curing the adhesive.

[0035] The specified sequence is particularly advantageous with regard to optimal dosage of the adhesive and filling of the cavity, as it effectively prevents underdosing and at the same time prevents the adhesive from oozing out in case of overdosing.

[0036] However, the steps of the procedure are not limited to the specified order. For example, it is also conceivable to introduce light-curing adhesive into the cavity before attaching the sensor unit to the structure.

[0037] A preferred further development of the method according to the invention is in which, in particular between process step b) and process step c), the light source is arranged on the fastening element.

[0038] A preferred further development of the method according to the invention is in which, in particular between process step b) and process step c), the light source is positioned next to the fastening element on the light-guiding element.

[0039] A further development of the method according to the invention is preferred in which, in particular after process step c), the light source is removed from the fastening element.

[0040] A further development of the method according to the invention is preferred in which, in particular after process step c), a protective cover is arranged on the fastening element.

[0041] Further advantages of the invention will become apparent from the description and the drawing. Likewise, the features mentioned above and those described in more detail below can each be used individually or in any combination according to the invention. The embodiments shown and described are not to be understood as an exhaustive list, but rather serve as examples for illustrating the invention. Detailed description of the invention and drawing

[0042] Fig. 1 shows a sensor arrangement with a first embodiment of a sensor unit and a structure to be monitored in a sectional view; Fig. 2 shows the first embodiment of a sensor unit made of Fig. 1in a perspective view, wherein the fastening element has a single cavity; Fig. 3 shows a second embodiment of a sensor unit in a perspective view, wherein the fastening element has two cavities; Figs. 4a-d show the various process steps of a method according to the invention for fastening a sensor arrangement with a sensor unit according to a third embodiment in a sectional view, wherein the fastening element has a cavity and a frame-side through-hole; Figs. 5a-d show the various process steps of a method according to the invention for fastening a sensor unit according to a fourth embodiment in a sectional view, wherein the fastening element has a cavity and a base-support element-side through-hole; Fig.Figures 6a-d show the various process steps of a method according to the invention for fastening a sensor unit according to a fifth embodiment in a sectional view, wherein the fastening element has two cavities with a through-hole on the frame side and a through-hole on the base support element side.

[0043] Fig. 1 shows a sensor arrangement 1 with a sensor unit 2, the structure to be monitored on a rail 3 is arranged. Sensor unit 2 has a mounting element. 10 and a sensor 12The structure 3 has a vertical section (rail neck) to which the sensor unit 2 is attached. The mounting of the sensor unit 2 does not place high demands on the underlying structure and is flexible with regard to its arrangement. The mounting element 10 can, for example, be attached to the structure 3 such that its contact surface is parallel to or at an angle to the direction of gravity. In other words, when mounted laterally on the structure 3, the mounting surface is essentially vertically oriented. However, other mounting positions are also possible.

[0044] The fastening element 10 has a plate-like base support element. 14 on and is parallel to the direction of extension 16 Structure 3 is arranged on the vertical rail section. A sealing frame.18 is arranged on the base support element 14 and rests predominantly, in particular completely, in a form-fitting manner against the structure 3. The sealing frame 18, the base support element 14 and the structure 3 define a cavity. 20. The sensor 12 is attached to the base support element 14 at the location opposite the cavity.

[0045] The sealing frame 18 has a frame passage recess. 22a on, which is used to fill cavity 20 with light-curing adhesive 24 The frame passage recess 22a is preferably also filled with adhesive 24 after the cavity 20 has been completely filled. This allows conclusions to be drawn about the degree of filling of the cavity 20.

[0046] Cavity 20 is in Fig. 1 already completely filled with light-cured adhesive 24, which forms the bonding agent between the fastening element 14 and the structure 3.

[0047] Fig. 2shows the first embodiment of sensor unit 2. Fig. 1 in a perspective view looking at the mounting side of the fastening element 10. The sealing frame 18 has the frame passage recess 22a on the upper circumference of the sealing frame 18. The terms "top" and "bottom" refer to an installation position in the direction of gravity on a predominantly vertically extending contact surface. The in Fig. 2 The arrangement of the frame passage recess 22a shown on the upper circumference of the sealing frame 18 particularly advantageously allows the filling of the adhesive 24 (in Fig. 2 (not shown) using gravity. In general, the frame passage opening 22a can be formed at any point on the sealing frame 18.

[0048] The base support element 14 is designed in multiple layers in the embodiment shown and has a transparent layer. 26 with a light-emitting surface28 The light-emitting surface 28 is directed into the cavity 20.

[0049] The transparent layer 26 has several light sources arranged inside the transparent layer. 30 (shown in black) which are distributed equidistantly across the connecting surface to the cavity 20 formed on the base support element 14, in particular the transparent layer 26. The transparent layer 26 has a light-emitting surface 28 in the area of ​​each light source 30, which serves to better distribute the light 36 (see Fig. 4c , 5c , 6c ) are formed in the cavity 20 (for the sake of clarity, only two light sources 30 and two light-emitting surfaces 28 are provided with reference symbols).

[0050] In the illustrated embodiment, the cavity 20 has a cross-section on the side facing the base support element 14 that is as similar as possible to that on the side facing the structure 3. This allows the same holding force to be generated between the adhesive 24 and the structure 3 as between the adhesive 24 and the base support element 14 when the fastening element 10 is arranged on the structure 3, thus preventing the introduction of too much adhesive 24 into the cavity 20. It is particularly advantageous that the sizes of the interfaces between the adhesive 24 and the base support element 14, and between the adhesive 24 and the structure 3, can be adapted to the surface properties of the base support element 14 and the structure 3, so that, for example, the interface between the adhesive 24 and the base support element 14 is larger or smaller than the interface between the adhesive 24 and the structure 3.This allows the surface-related holding force to be formed uniformly despite different area ratios.

[0051] Fig. 3 shows a second embodiment of a sensor unit 302. The basic support element 14 Together with two sealing frames 18, it forms two spatially separated cavities 320. By forming several cavities 20, which are located in the Fig. 3 The example shown does not cover the entire surface of the base support element 14, provided the fastening element has the same dimensions. 310, the number of light sources 30 and the amount of adhesive required 24 (in Fig. 3 (not shown) compared to the in Fig. 2 The embodiment shown is reduced. Each of the two cavities 20 has two frame through-recesses 22a for filling with the adhesive 24 (see Fig. 4c , 5c , 6c) (for the sake of clarity, only one light source 30 is marked with a reference symbol). The arrangement of the cavities 20 on the base support element 14 can be particularly advantageous at points on the base support element 14 that are functionally relevant for the sensor 12.

[0052] By way of example, but not exhaustively, the arrangement of the cavities 20 when a strain sensor is mounted on the base support element 14 is mentioned. In this case, by arranging the cavities 20 and thus stiffening the fastening element 310 after the adhesive 24 has cured in the area of ​​the strain sensor's strain measurement points located on the base support element 14, a particularly accurate transmission of the structure's expansion (not shown) to the sensor 12 can be achieved.

[0053] Fig. 4a -d show a sensor arrangement 401 with a sensor unit 402 comprising a fastening element 410with integrated light sources 30, which is attached to the structure 3 according to process step a). For the temporary attachment of the sensor unit 402 to the structure 3, the sealing frame 18 has an adhesive on its side in contact with the structure 3. 32, e.g., in the form of an adhesive strip. This makes the subsequent process steps particularly easy to carry out, as the sensor unit 402 does not need to be permanently pressed against the structure 3. Alternatively or additionally, manual or machine pressing of the sensor unit 402 can be provided.

[0054] Fig. 4b Figure 1 shows the filling of the adhesive 24 into the cavity 20 according to process step b) via the frame passage recess 22a formed on the top of the sealing frame 18. The adhesive 24 is supplied by means of a cartridge. 34provided. In general, the adhesive 24 can be provided in various ways; application using a cartridge 34 is particularly advantageous with regard to the dosage of the adhesive 24.

[0055] Fig. 4c shows the emission of light rays 36 into the cavity 20 according to process step d) for curing the light-curing adhesive 24. The sensor unit 401 according to Fig. 4a-d It features light sources 30, which are arranged inside the cavity 20. Light-emitting surfaces 428are arranged directly on the light sources 30, in particular in the form of a housing, most preferably in the form of an epoxy resin lens (for the sake of clarity, only one light source 30, one light-emitting surface 428, and one representative light beam 36 are provided with a reference numeral). For the energy supply of the light sources 30, the sensor unit 402 has an integrated battery (not shown), which is connected via switchable electrical conductors. 40(for example, in the form of a circuit board) is connected to the light sources 30. After the adhesive 24 is poured in, the light sources 30 are switched on. The battery (not shown) has an electrical capacity that provides the energy for the illumination time required for the adhesive 24 to cure. After the adhesive 24 has cured, the light sources 30 and the battery (not shown) remain as so-called "lost elements" on the sensor unit 402. An external power supply is also conceivable. It is also conceivable, if the sensor 12 itself includes a power supply, to supply the light sources 30 with energy via the power supply provided for the operation of the sensor 12 (not shown).

[0056] The sensor unit 402 has a protective cover arranged on the fastening element 410, in particular the base support element 14 and the sealing frame 18. 38The protective cover 38 is made according to the embodiment from Fig. 4c and Fig. 4d arranged by means of a press fit on the sensor unit 402.

[0057] Fig. 4d shows the sensor arrangement 401 in its final state with cured adhesive 24.

[0058] Fig. 5a -d show a method for attaching a sensor unit 502 according to a fourth embodiment on structure 3, to accommodate a sensor arrangement 501 to obtain the fastening element 510 It features the fully circumferential sealing frame 18. A carrier passage recess. 22b is in the basic support element 514 and the circuit board 40.

[0059] Fig. 5b The figure shows the filling of the light-curing adhesive 24 into the cavity 20 via the carrier passage recess 22b in the base carrier element 514, which makes the filling process easier to carry out because a cartridge (light-tight) can be attached more easily.

[0060] Fig. 5c Figure 24 shows the curing of the adhesive by exposure to light via the light sources 30.

[0061] Once the adhesive 24 has cured, the light exposure can be stopped. ( Fig. 5d ) Fig. 6a -d show a method for providing a sensor arrangement 601 by attaching a sensor unit 602 according to a fifth embodiment on structure 3.

[0062] A fastening element 610 features a light-guiding element 42 between a base support element 614and two cavities 20. Light sources 30 are detachably arranged around the circumference of the light-guiding element 42. The light sources 30 emit light rays 36 into the light-guiding element 42. The light-guiding element 42 is designed to guide the light rays 36 introduced by the light sources 30 through the light-guiding element 42 to the cavities 20 and to couple them out into the cavities. For this purpose, the light-guiding element 42 has light-emitting surfaces in the areas of the cavities 20. 628 The introduced light rays 36 exit the light-guiding element 42 via the light-emitting surfaces 628 ( Fig. 6c The cavities 20 are accordingly illuminated indirectly by the light sources 30, by means of light coupling from the outside. The light coupling into the light-conducting element 42 takes place at least at one point, in particular at several points, and most preferably completely at the light-conducting element 42.

[0063] Fig. 6b Figure 1 shows the filling of the cavities 20 through a frame passage opening 22a and a beam passage opening 22b. The frame passage opening 22a is formed in the sealing frame 18, while the beam passage opening 22b is formed in the base support element 614 and the light-guiding element 42. The sealing frame 18 is continuous and, in the example shown, does not have a passage opening. However, it is also possible to fill both cavities 20 through frame passage openings 22a in the corresponding sealing frames 18 and / or through appropriately positioned beam passage openings 22b in the base support element 614.

[0064] Fig. 6cFigure 3 shows the curing process of the light-curing adhesive 24 after the cavities 20 have been filled. The light-guiding element 42 can have nano- and / or microstructures, particularly in the area of ​​the light-emitting surface 628, to couple the light rays 36 towards the structure 3 and enable the most homogeneous illumination of the cavities 20 possible. The light sources 30 are powered, for example, by an external battery (not shown).

[0065] Fig. 6d Figure 1 shows the sensor assembly 601 in its finished state (sensor unit 602 attached to structure 3). The light sources 30 were detached from the fastening element 610 after the curing process. The protective cover 38 is attached to the fastening element 610 by means of an interference fit.

[0066] Considering all the figures in the drawing together, the invention relates to a holding device 10, 310, 410, 510, 610 for a sensor 12, which can be attached to a structure 3 by means of a light-curing adhesive 24. The light-curing adhesive 24 is cured by direct and / or indirect illumination of the cavities 20 provided for receiving the light-curing adhesive 24. The invention further relates to a sensor unit 2, 302, 402, 502, 602 with a sensor 12 and a holding device 10, 310, 410, 510, 610, a sensor arrangement 1, 401, 501, 601 with a sensor unit 2 and a structure 3, and a method for providing an arrangement 1, 401, 501, 601. Reference symbol list

[0067] 1, 401, 501, 601 Sensor assembly; 2, 302, 402, 502, 602 Sensor unit; 3 Structure; 10, 310, 410, 510, 610 Fastening element; 12 Sensor; 14, 514, 614 Base support element; 16 Extension direction of structure; 18 Sealing frame; 20, 320 Cavity; 22a Frame passage recess; 22b Support passage recess; 24 Light-curing adhesive; 26 Transparent layer; 28, 428, 628 Light-emitting surface; 30 Light source; 32 Adhesive; 34 Cartridge; 36 Light rays; 38 Protective cover; 40 Switchable electrical conductors / circuit board 42 Light-conducting element. Bibliography

[0068] [1] Elastic bonding – Reducing system costs in the solar industry; Issue 6 / 2011 November-December: Solar Energy; Pages 50, 51. [2] Renewable energies – Sealing / Bonding / Potting – Photovoltaic modules; OTTO-Chemie; https: / / www.otto-chemie.de / de / erneuerbare-energien. [3] European patent application 19180254.5; [4] DE 10 2017 216 811 A1.

Claims

1. Fastening element (10, 310, 410, 510, 610) for attaching a sensor (12) to a structure to be monitored (3), wherein the fastening element (10, 310, 410, 510, 610) comprises: - a base support element (14, 514, 614); - a sealing frame (18) for sealing the base support element (14, 514, 614) against the structure (3); - a cavity (20, 320) for receiving a light-curing adhesive (24), wherein the cavity (20, 320) is bounded on one side by the base support element (14, 514, 614) and on its circumference by the sealing frame (18); - at least one light-emitting surface (28, 428, 628) for coupling light rays (36) into the cavity (20, 320).

2. Fastening element (10, 310, 410, 510, 610) according to claim 1, comprising at least one through-hole (22a, 22b) for introducing the light-curing adhesive (24) into the cavity (20, 320).

3. Fastening element (10, 310, 410, 510, 610) according to claim 1 or 2, comprising at least one light source (30), in particular a light-emitting diode, for direct or indirect at least partial illumination of the cavity (20, 320).

4. Fastening element (10, 310, 410, 510, 610) according to claim 3, wherein a plurality of light sources (30) are arranged spaced apart from one another, in particular equidistantly.

5. Fastening element (10, 310, 410, 510) according to claim 3 or 4, wherein the light sources (30) are arranged within the cavity (20, 320).

6. Fastening element (10, 310) according to claim 3 or 4, wherein the base support element (14) comprises a transparent layer (26) in which the light source (30) is arranged.

7. Fastening element (10, 310, 410, 510, 610) according to any one of claims 3 to 6, wherein the light source (30) is configured to emit UV light.

8. Fastening element (610) according to one of the preceding claims, comprising a light-guiding element (42) for light-guiding connection of the light source (30) with the light-emitting surface (628).

9. Fastening element (610) according to claim 8, wherein the light source (30) is arranged in the circumferential direction of the sealing frame (18) on and / or in the sealing frame (18).

10. Fastening element (610) according to claims 3 to 9, wherein the light source (30) is detachably arranged on the base support element (614) and / or the sealing frame (18).

11. Sensor unit (2, 302, 402, 502, 602) with a sensor (12) and a fastening element (10, 310, 410, 510, 610) according to one of the preceding claims, wherein the sensor (12) is arranged on the side of the base support element (14, 514, 614) opposite the cavity (20, 320).

12. Sensor unit according to claim 11, wherein the sensor (12) is a strain sensor, preferably a rail monitoring element with an optical fiber with fiber Bragg grating.

13. Sensor arrangement (1, 401, 501, 601) with a sensor unit (2, 302, 402, 502, 602) according to claim 11 or 12 and a structure (3) to be monitored, wherein the sensor unit (2, 302, 402, 502, 602) is positioned on the structure (3) such that the cavity (20, 320) of the sensor unit (2, 302, 402, 502, 602) is bounded by the structure (3) on the side opposite the base support element (14, 514, 614) and wherein the cavity (20, 320) is at least partially filled with a light-curing, in particular UV-light-curing, adhesive (24).

14. Sensor arrangement according to claim 13, wherein a lighting device with at least one light source (30) can be arranged, in particular attached, to the sensor unit (602) and wherein the lighting device is designed for direct and / or indirect illumination of the cavity (20, 320).

15. Method for attaching a sensor unit (2, 302, 402, 502, 602) according to claim 11 or 12 to a structure (3), wherein the method comprises the following process steps: a) placing the sensor unit (2, 302, 402, 502, 602) onto the structure (3); b) introducing the light-curing adhesive (24) into the cavity (20, 320) of the sensor unit (2, 302, 402, 502, 602); c) introducing light (36) into the cavity (20, 320) for the purpose of curing the adhesive (24);