Monitoring attachment for a nut, and assembly having at least two monitoring attachments of this kind

Abstract

The invention relates to a monitoring attachment for monitoring a nut (9) of a threaded joint, comprising a ring (1) which is guided around the outer periphery of the nut (9) and has a conductor loop, wherein, in the case of a deformation, crack and / or rupture of the nut (9), the ring (1) is deformed and the conductor loop is interrupted. The monitoring attachment is characterized in that at least one securing element for a tension means (81) is located on the ring (1). The invention also relates to an assembly comprising at least two monitoring attachments of this kind, wherein one tension means (81) which connects two adjacent monitoring attachments is provided in each case.

Description

[0001] Monitoring attachment for a nut and arrangement with at least two such monitoring attachments

[0002] The invention relates to a monitoring attachment for monitoring a nut of a screw connection, comprising a ring with a conductor loop guided around an outer circumference of the nut. In the event of deformation, a crack, and / or breakage of the nut, the ring is deformed and the conductor loop is interrupted. The invention further relates to an arrangement with at least two such monitoring attachments.

[0003] Nuts in highly stressed bolted connections, such as those in wind turbines, are monitored for safety reasons to detect any damage as quickly as possible. Such highly stressed bolted connections in wind turbines are typically part of flanged connections, in which a large number of bolted connections are arranged around the circumference of the flange. If a break in one or more nuts is detected, they can be replaced before the entire flange connection is at risk of breaking. This way, personal injury and / or economic consequential damage can be avoided.

[0004] EP 3 047 144 B1 describes such a monitoring attachment. It has a monitoring body designed as a nut cap that radially surrounds the nut around its circumference. If damaged, e.g., if the nut bursts, the monitoring body is also destroyed. The monitoring body has a circumferential electrical conductor in the form of an electrically conductive coating. Destruction of the monitoring body leads to an interruption of the electrical line, which is detected.

[0005] This design has proven functionally effective, but cannot be reused if the monitoring body breaks. A monitoring attachment of the type mentioned above is known from the publication WO 2022 / 063978A1, in which the ring surrounding the nut consists of at least two segments that are held together by a force fit at a radial connection point. A conductor loop is formed in the ring, which is guided via contacts at the connection point. If the nut is damaged, the connection point represents a designated interruption point for the ring and thus also for the conductor loop. The ring is deformed in a non-destructive manner and, after replacing the nut, can be placed around the new nut and closed again at the connection point. The connection point is designed, for example, in the form of plug contacts.

[0006] Both systems reliably detect nut damage, but the monitoring attachment is unable to detect nut loosening at an early stage. If the nut continues to loosen, a connecting cable connecting the conductor loop to an electrical monitoring device may break, thus detecting the nut loosening. However, it would be desirable if nut loosening could be detected even with a slight twist of the nut, for example, by an angle of a few tens of degrees.

[0007] It is therefore an object of the present invention to improve the monitoring attachment mentioned above so that it can reliably detect not only damage to a monitored nut but also its loosening at an early stage. A further object is to create an arrangement of at least two such monitoring attachments.

[0008] This problem is solved by a monitoring attachment or an arrangement of monitoring attachments having the features of the respective independent claim. Advantageous embodiments and further developments are the subject of the dependent claims.

[0009] A monitoring attachment according to the invention of the type mentioned at the outset is characterized in that at least one fastening element for a traction device is arranged on the ring. The traction device can be guided from the ring to a fixed point using the fastening element. If the nut loosens and twists, the traction device exerts a pull on the ring, which leads to a deformation of the ring and thus also to an interruption of the conductor loop. The fixed point to which the traction device is attached can, for example, be arranged in the region of a flange that is mounted using the monitored nut. It is also possible to use a fastening element of another monitoring attachment as the fixed point, so that the fixed point is assigned to another monitored nut, which is preferably located adjacent to the previously mentioned monitored nut.

[0010] An arrangement according to the invention is characterized by at least two such monitoring attachments, whose rings are connected to each other by the tension means. Such an arrangement can be used in particular for a plurality of bolts, for example, the bolts of a flange connection of wind turbine rotor blades. If, as with a flange, a plurality of nuts are arranged in a circle, no separate fixed point is required, since all tension means can then run between adjacent monitoring attachments.

[0011] In an advantageous embodiment of the monitoring attachment, the fastening element is an eyelet, which is fastened in particular to an outer circumference of the ring. The eyelet is preferably fastened to the ring in such a way that a strong pull exerted on the eyelet may deform the ring, but in particular interrupts the conductor loop arranged in the ring. It can be provided that the eyelet protrudes through a side wall of the ring and encloses the conductor loop. When the ring is pulled, the eyelet is pulled out of the ring, thereby separating the enclosed conductor loop. This embodiment is particularly suitable for a design of the monitoring attachment in which the ring is deformed in such a way that, if the nut is damaged, it is destroyed along with the conductor loop.

[0012] In a further advantageous embodiment of the monitoring attachment, the ring is formed from at least two segments that are frictionally connected to one another at a connection point, with the conductor loop being routed via contacts at the connection point. In this embodiment, the monitoring attachment is reusable after a triggering event, for example, after damage to the nut or after the nut has been loosened, since the ring is not destroyed but deformed to the extent that its segments separate from one another at the connection point. When the segments separate, the conductor loop at the contacts is also interrupted.

[0013] In this embodiment too, the fastening element is advantageously designed as an eyelet arranged on one of the segments. It is preferably positioned in the region of the connection point so that pulling on the eyelet results in a force in the direction of the opening movement at the connection point. The connection point is preferably designed as a plug-in connection which can be inserted or pulled apart in the circumferential direction of the ring. The eyelet is advantageously positioned so that pulling on the eyelet results in a force counter to the insertion direction of the plug-in connection. In a further advantageous embodiment, the ring comprises two segments which have at least one connection point with contacts for the conductor loop, wherein fastening elements, for example eyelets, for the pulling means are provided on each segment.

[0014] This embodiment is particularly suitable for an arrangement in which a plurality of monitoring attachments are used in conjunction with a plurality of nuts arranged next to one another, wherein a traction means is provided between two adjacent monitoring attachments, which in each case connects a segment of the monitoring attachment to a segment of the adjacent monitoring attachment.

[0015] In an advantageous embodiment of the arrangement, at least one monitoring attachment is provided with an adapter having an external hexagon section and a connected internal hexagon section. The ring of the monitoring attachment is guided around the outer circumference of the external hexagon section, and the adapter engages with its internal hexagon section around the outer circumference of a nut. Advantageously, in this embodiment, a monitoring attachment of one size can be used for a different nut or screw head size using such an adapter, wherein both damage and twisting of the nut are transmitted to the monitoring attachment by the adapter. The two hexagon sections of the adapter can lie one inside the other if the external hexagon section has a larger wrench size than the internal hexagon section. Otherwise, the two hexagon sections can also be placed on top of each other (i.e.offset in the axial direction).

[0016] The invention is explained in more detail below using exemplary embodiments and figures. The figures show:

[0017] Figure 1 shows an arrangement of several nuts, each with a monitoring attachment;

[0018] Figure 2a shows the arrangement according to Figure 1 after turning one of the nuts;

[0019] Figure 2b is an enlarged detail of Figure 2a; Figure 3 is an exploded view of a nut with an adapter and a monitoring attachment;

[0020] Figure 4 shows an arrangement of several nuts, each with an adapter and a monitoring attachment;

[0021] Figure 5a shows the arrangement according to Figure 4 after turning one of the nuts; and

[0022] Figure 5b is an enlarged detail of Figure 5a.

[0023] Figures 1 and 2a, b, and 4 and 5a, b, respectively, show two exemplary embodiments of an arrangement of multiple monitoring attachments for nuts 9 to be monitored. Figures 1 and 4 each show the arrangement with correctly tightened nuts 9, whereas in the illustrations in Figures 2a and 5a, one of the nuts 9, for example the middle one of the three nuts 9 shown, has come loose and twisted, which is detected by the arrangement of monitoring attachments. The area of ​​the middle nut 9 is shown enlarged in Figures 2b and 5b.

[0024] In all figures, identical reference symbols identify identical or identically functioning elements. For reasons of clarity, not every element in every figure is provided with a reference symbol.

[0025] Figures 1 and 2 show a first exemplary embodiment of an arrangement of three complete monitoring attachments, arranged on three adjacent nuts 9, each in a three-dimensional representation. In addition to the three complete monitoring attachments, two monitoring attachments are shown only partially and without the nuts in order to illustrate the structure of the monitoring attachments in more detail. Figure 1 shows the monitoring attachments in a closed and operational state.

[0026] The nuts 9 are, for example, nuts of a screw connection of a flange fastening in a wind turbine. Such nuts can, for example, have the size M30. Instead of the nut 9, the monitoring attachment according to the application can of course also be used to monitor a screw or bolt head of a screw connection. In this sense, nuts and screw or bolt heads are to be considered synonymous within the scope of the application. Each monitoring attachment has a ring 1 radially surrounding the nut 9 around its circumference, which ring is composed of two semi-annular segments 2, 2'. The segments 2, 2' are preferably plastic elements that are manufactured in one piece, e.g., using a plastic injection molding process.

[0027] Due to their shape as half rings, the two segments 2, 2' complement each other to form the ring 1 in the closed state. On the inner side facing the nut 9, the segments 2, 2' are provided with an inner contour 3 which, when assembled, forms a regular hexagon that reflects the outer contour of the nut 9. Alternatively, a regular dodecagon can be formed instead of a hexagon. The dodecagon design allows the monitoring attachment to be placed on the nut 9 rotated in 30° increments. When designed with a hexagonal inner contour 3, placement in 60° increments is possible. In both cases, the assembled segments 2, 2' enclose the nut 9 tightly, i.e. with little play and preferably at least in a form-fitting manner at certain points, so that a change in the shape of the nut 9 due to deformation, breakage or cracking leads to a force acting on the segments 2, 2'.

[0028] In the illustrated embodiment, magnet receptacles 4 for magnets are formed in the segments 2, 2'. The monitoring attachment can be fastened by means of the magnets in an area next to the nut 9, e.g. on the flange through which the screw connection passes. In this case, the monitoring attachment is designed to be placed on a nut 9 with a washer. For this purpose, the magnet receptacles 4 are positioned so that the magnets 4 rest on the component, e.g. the flange, next to the washer. For this purpose, the magnet receptacles 4 each have a dome that projects downwards beyond the otherwise boundary edge of the segment 2, 2'. In the example shown, two magnet receptacles 4 are provided on the segment 2' and one magnet receptacle 4 on the segment 2. The number and distribution of the magnets can vary in alternative embodiments.

[0029] Between each segment 2, 2', at least one force-locked connection is provided, which opens in the event of a break, crack, and / or other damage or deformation of the nut 9, thereby interrupting an electrical contact established within the connection. The connection is opened non-destructively against a locking force, so that after replacing the damaged nut 9, the monitoring attachment can be placed on the new nut 9, whereby the connection is closed again, the electrical connection is re-established, and the monitoring attachment is ready for use again.

[0030] In the present exemplary embodiment, the segments 2, 2' are electrically and mechanically connected to one another at both connection points at the radial ends of the segments 2, 2' via a plug-in connection. The plug-in connection is formed in each case by the interaction of a plug-in section 5 and a receiving section 6. In the example shown, the segment 2' has the plug-in section 5 at both ends and the segment 2 has the receiving section 6 at both ends. Alternatively, the segments 2, 2' could also be mirror-inverted with regard to the plug-in connections, with each segment 2, 2' having a plug-in section 5 at one radial end and a receiving section 6 at the other radial end.

[0031] The plug-in section 5 comprises a protruding shaft and a locking element 51. The shaft can be provided with a circumferential sealing ring to prevent moisture from penetrating the plug connection.

[0032] The receiving section 6 has a corresponding shaft receptacle into which the shaft can be inserted. Furthermore, counter-locking elements 61 are provided, which, when inserted, engage with the locking elements 51 and mechanically fix the plug connection in the closed state. The fixation is designed such that the plug connection is securely held in the closed state and that, during normal operation of the monitored device, forces acting on the segments 2, 2', such as acceleration forces, do not open the plug connection.

[0033] If the nut 9 breaks or is otherwise damaged, the plug-in section 5 and the receiving section 6 are at least partially moved away from each other against the locking forces, thus opening the plug connection, which occurs non-destructively.

[0034] A conductor loop runs through the ring 1 of each monitoring attachment, which is routed via contacts of the connector. Pulling the connector apart opens the conductor loop, which can be detected externally by a continuity measurement (resistance measurement). For this purpose, a contact arrangement 7 with two connection contacts is provided on each segment 2, 2', to which connecting cables can be mounted, which forward the two ends of the conductor loop from the monitoring attachment to an external evaluation arrangement.

[0035] Within a segment 2, 2', conductor sections of the conductor loop run from one contact of the contact arrangement 7 to the plug-in section 5 or the receiving section 6. In the arrangement shown, the conductor sections of the conductor loops of all monitoring attachments are connected in series via connecting cables 71, so that an interruption in one of the monitoring attachments leads to an interruption in the series connection of the conductor loops, which can be detected accordingly with a continuity measurement.

[0036] According to the invention, at least one fastening option for a traction device 81 is arranged on each ring 1, preferably on each segment 2, 2'. In the example shown, an eyelet 8 is formed on each segment 2, 2', into which a tension band is inserted as a traction device 81. Each traction device 81 connects the eyelets 8 of mutually facing segments 2, 2' of adjacent monitoring attachments. The eyelets 8 are arranged on the segments 2, 2' and the traction devices 81 are aligned in such a way that a pull on the traction device 81 acts axially on one of the connectors of the ring 1.

[0037] If, as shown in Figure 2a for the middle of the nuts 9, this nut 9 comes loose and is rotated by a few degrees to a few tens of degrees compared to its original fastening state, a pull is exerted on the plug connector of the corresponding monitoring attachment and / or the adjacent monitoring attachment via one of the two pulling means 81 assigned to this monitoring attachment. The pull then leads to an opening of at least one of the rings 1 on one of the plug connectors. As with the breakage or other deformation of one of the nuts 9, the conductor loop is thus interrupted and the rotation of the nut 9 is thus detected. The enlargement of Figure 2b shows that the locking between the corresponding locking element 51 and the associated counter-grid element 61 has been released and the plug-in section 5 has been pulled out of the receiving section 6 by a distance d.

[0038] The eyelets 8 in conjunction with the traction means 81 thus extend the functionality of the monitoring attachments in such a way that, in addition to a break or other damage to one of the nuts 9, a twisting of the nut 9 can also be detected easily and reliably and via the same detection mechanism.

[0039] If a monitoring attachment is used separately to monitor only one nut, the tensioning device 81 can lead from the eyelet 8 to another fixed point. The tensioning device 81 can, for example, be hooked with its free end into a hook mounted on the flange.

[0040] In the embodiment of Figures 4 and 5a, b, the same monitoring attachments are used as in the first embodiment of Figures 1 and 2. However, the monitored nuts 9, here again three nuts 9 arranged next to each other, have a larger wrench size than the nuts 9 in the embodiment of Figures 1 and 2.

[0041] The nuts 9 of the second embodiment in Figures 4 and 5a, b can, for example, be M36 nuts, whereas the nuts 9 from the first embodiment are M30 nuts. Accordingly, the monitoring attachments used in both embodiments would then be designed for M30 nuts.

[0042] In order to be able to use the monitoring attachments in the same construction in the second embodiment, adapters 10 are used, which are each placed onto the respective nut 9 before mounting each monitoring attachment. The adapters 10 have a hexagon socket section 101 located at the bottom in Figures 3 and 4, which can be placed onto the nut 9 like a cap and whose internal dimensions are selected so that they can be placed onto the M36 nut 9. To fix the adapters 10, a threaded hole is made in at least one side surface of the hexagon socket section 101, into which a clamping screw 102, for example a stud screw, is screwed.

[0043] Figure 3 shows the mounting of a monitoring attachment onto a nut 9 using an adapter 10 in the form of an exploded view. Here, the nut 9 is screwed onto a thread 92 of a bolt 91, as an example.

[0044] Connected to the hexagon socket section 101 is an upwardly projecting hexagon socket section 103, which has the outer contour of an M30 nut and around which the monitoring attachment is placed. A washer 104 is incorporated between the hexagon socket section 101 and the hexagon socket section 103, which allows the monitoring attachment to be held on the adapter 10 using the magnets of its magnetic receptacles 4.

[0045] The adapter 10 is preferably made of a plastic material such that a crack that occurs in the hexagon socket section 101 upon damage to the nut 9 continues into the hexagon socket section 103. Thus, upon damage to the nut 9, the ring 1 of the monitoring attachment is opened, and the damage to the nut 9 is detected accordingly.

[0046] As Figure 5a shows, a rotation of one of the nuts 9, for example the middle one of the nuts 9 shown in Figure 4, also leads to a rotation of the adapter 10 and thus of the monitoring attachment, whereby the ring 1 of the affected monitoring attachment or of a neighboring monitoring attachment is opened by means of the pulling means 81. In the enlargement of Figure 5b, again analogous to Figure 2b, it can be seen that the locking between the corresponding locking element 51 and the associated counter-grating element 61 has been released and the plug-in section 5 has been pulled out of the receiving section 6 by the distance d.

[0047] Advantageously, in this embodiment, a monitoring attachment of one size can be used for other nut sizes using the adapter 10, wherein the adapter 10 transmits both damage and twisting of the nut 9 to the monitoring attachment.

[0048] In all monitoring attachments shown in the figures, segments 2 and 2' are each connected or separable at two connection points. Alternatively, only one connection point with contacts for the conductor loop can be provided, and instead of the second connection point, a hinge can be provided that pivots the two segments 2, 2' together. List of reference symbols

[0049] 1 ring

[0050] 2, 2' segment

[0051] 3 Inner contour

[0052] 4 Magnetic holder

[0053] 5 plug-in section

[0054] 51 locking element

[0055] 6 Recording section

[0056] 61 Counter-locking element

[0057] 7 Contact arrangement

[0058] 71 connecting cables

[0059] 8 eyelets

[0060] 81 traction devices

[0061] 9 Mother

[0062] 91 bolts

[0063] 92 threads

[0064] 10 adapters

[0065] 101 hexagon socket section

[0066] 102 clamping screw

[0067] 103 External hexagon section

[0068] 104 Washer d Distance

Claims

Claims 1 . Monitoring attachment for monitoring a nut (9) of a screw connection, comprising a ring (1) guided around an outer circumference of the nut (9) and having a conductor loop, wherein in the event of a deformation, a crack and / or a breakage of the nut (9), the ring (1) is deformed and the conductor loop is interrupted, characterized in that at least one fastening element for a traction means (81) is arranged on the ring (1).

2. Monitoring attachment according to claim 1, wherein the fastening element is an eyelet (8).

3. Monitoring attachment according to claim 2, wherein the eyelet (8) is arranged or formed on an outer circumference of the ring (1).

4. Monitoring attachment according to claim 2 or 3, wherein the eyelet (8) projects through a side wall of the ring (1) and encloses the conductor loop.

5. Monitoring attachment according to one of claims 1 to 4, in which the ring (1) is formed from at least two segments (2, 2') which are non-positively connected to one another at a connection point, the conductor loop being guided via contacts at the connection point.

6. Monitoring attachment according to claim 2 and 5, wherein the eyelet (8) is positioned in the region of the connection point in such a way that a pull on the eyelet (8) exerts a force in the direction of an opening movement of the connection point.

7. Monitoring attachment according to claim 2 and 5, wherein the connection point is designed as a plug connection which can be inserted or pulled apart in the circumferential direction of the ring (1).

8. Monitoring attachment according to one of claims 5 to 7, wherein the at least one connection point has contacts for the conductor loop, each segment (2, 2') having one of the fastening elements.

9. Arrangement of at least two monitoring attachments according to one of claims 1 to 8, wherein a traction means (81) is provided in each case which connects two adjacent monitoring attachments.

10. Arrangement according to claim 9, wherein each of the monitoring attachments consists of at least two segments (2, 2'), wherein between two adjacent monitoring attachments a traction means (81) is provided, which connects one of the segments (2, 2') of one monitoring attachment to one of the segments (2, 2') of the other monitoring attachment.

11. Arrangement according to claim 9 or 10, wherein at least one monitoring attachment is provided with an adapter (10), wherein the adapter (10) has an external hexagon section (103) and a hexagon socket section (102) connected thereto, and wherein the at least one monitoring attachment is guided with its ring (1) around the outer circumference of the external hexagon section (103) and the adapter (10) with its hexagon socket section (102) engages around an outer circumference of a nut (9).

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