EP1787035A1

EP1787035A1 - Loosening indicator for a bolt or nut and a corresponding system

Info

Publication number: EP1787035A1
Application number: EP04767143A
Authority: EP
Inventors: Ari Pääkkö
Original assignee: Paakko Eero
Current assignee: Paakko Eero
Priority date: 2003-09-03
Filing date: 2004-08-30
Publication date: 2007-05-23
Also published as: WO2005021983A1; FI20035142A0; CA2536801A1

Abstract

The invention relates to a loosening indicator for a nut/bolt (9), which is an indicator device to be installed in connection with the nut/bolt (9). The indicator device includes detector means (31, 31') for detecting the loosening of the nut/bolt, transmitter means (30), and power supply means (32) for indicating the loosening. The invention also relates to a corresponding system in the indication of loosening.

Description

LOOSENING INDICATOR FOR A BOLT OR NUT AND A CORRESPONDING SYSTEM

The present invention relates to a loosening indicator for a bolt/nut, which is an indicator device to be installed in connection with the bolt/nut. In addition, the invention also relates to a system for indicating the loosening of a bolt/nut.

International (PCT) patent publication O-02/101249 discloses a locking tightener for a bolt/nut. In it, a series of bolts can be locked to each other with the aid of polygonal plates.

Arranged in this way, they also form a kind of primitive loosening indicator. The driver of the vehicle must check the locking plates of the entire ring of bolts visually at regular intervals. Any bolt that has begun to rotate will be easily detected from the rotated locking plate, which breaks the otherwise symmetrical pattern.

In articulated vehicles, for example, there can be tens of objects, such as, for example nuts or bolts, both of which will hereinafter be referred to by the common name nut, which demand checking of their state of tightness. Further, in some joints, the nut cannot even be accessed to check its state of tightness, or at least it is extremely difficult, due, for example, to its difficult location. Further, if a nut begins to loosen even slightly, any subsequent further loosening may take place very rapidly. Awareness of such a rapid loosening will not be achieved, despite even tightness checks made at reasonable intervals .

Further, the loosening of nuts and bolts causes problems, not only in the said heavy vehicles, but also in industry, in which there are a great many nut and bolt attachments in machinery. Nut-loosening vibration and oscillations occur in machinery. The attachment points may be located in such places, in which it is difficult, if not impossible, to check their tightness. Examples from industrial machinery include paper, metal- working, and printing machines. Additional examples include bolted joints in oil and gas pipes and in buildings and structures, all of the aforementioned being only some examples of applications of nut and bolt joints.

The invention is intended to create a loosening indicator for a bolt or nut that can be observed and monitored more easily and with less effort. The characteristic features of the indicator according to the invention are stated in Claim 1. In addition, the invention also relates to a corresponding system, the characteristic features of which are stated in Claim 12.

The nut/bolt loosening indicator according to the invention is an indicator device to be installed in connection with the nut/bolt. The indicator device includes detector means for detecting loosening, transmitter means and power-source means for indicating loosening. According to one preferred embodiment, the transmitter means can include a wireless transmitter. The invention can thus be implemented even in extremely difficult applications.

According to one embodiment, the indicator according to the invention can be an angle or distance detector that is, as such, known, together with its counter-pieces, which is connected to detect rotation of the nut/bolt. According to one embodiment, the indicator can be arranged to be linked in a set manner to a remote monitoring point over a wireless data communications link. The party monitoring the state of tight- ness, for example, the driver of a vehicle, can be notified by a cab alarm, if a bolt equipped with a detector loosens. State data requests can naturally also be sent to the indicator from a remote monitoring point. In that case, the indicator need not perform continuous monitoring, thus saving power. According to a first embodiment, the detector means can be formed of two response elements. One of these elements can be arranged permanently in the vicinity of the attachment location and the other can be in connection with the nut/bolt. On the other hand, the nut/bolt or the vicinity of the attachment location can itself form the detector element, if permitted by the situation.

According to a second embodiment, the detector means can be arranged in a spring element arranged in connection with the attachment location, or even the spring element itself can form the detector. For example, the spring element can be set to tighten the nut to the pull position. Thus, when the nut loosens, the spring stretches and the detecting elements arranged in connection with it sends an alarm of the nut's loosening. On the other hand, it may be possible to detect the loosening of the attachment point from the spring' s stretch itself. In that case, the spring itself forms the detector.

According to a third embodiment, the indicator can be implemented to operate mechanically. One way is to use magnets. This will make its operation reliable, even in demanding conditions. Some other types of sensors, which can be applied in the invention, include piezoelectric sensors and strain gauge transducers.

The invention can also be applied in other applications than vehicles, which are liable to loosening, such as in vibrating conditions in general. The other characteristic features of the invention will become apparent from the accompanying Claims and the description portion.

The invention, which is not restricted to the embodiments described in the following, is examined in greater detail with reference to the accompanying drawings, in which Figure 1 shows a spring equipped with a rotation detector,

Figure 2 shows a spring-loaded locking plate equipped with a detector, Figures 3a and 3b show a variation of Figure 2

Figure 4 shows the lower surface of the base locking plate,

Figures 5a - 5e show a third variation of the indicator and cross-sections of it, as well as a local indicator,

Figure 6 shows a permanently installed indicator and an alternative manner of attaching it,

Figures 7a and 7b show a second permanently installed indi- cator,

Figure 8 shows a third permanently installed indicator,

Figures 9a and 9b shows a fourth permanently installed indicator, Figures 10a and 10b show a fifth indicator solution,

Figure 11 shows an example of a warning panel in an articulated vehicle,

Figure 12 shows an example of an application of a system according to the invention, Figures 13a and 13b show some indicator solutions applied to cross-head/Allen screw applications,

Figures 14a and 14b show some indicator solutions in a recessed attachment,

Figures 15a and 15b show an example of a wheel trim applica- tion, viewed from different directions and

Figures 16a and 16b show examples when applying different types of sensor.

The nut/bolt 9 loosening indicator is a indicator device to be installed in connection with a nut/bolt 9, 9', or any other attachment element whatever equipped with a thread. These attachment elements have the common feature of being liable to loosen, i.e. to open. Screw attachments can also be included with these. The indicator device includes detector means 31, 31' for detecting the loosening of the nut/bolt 9, 9' (for example, rotation or distance detector), transmitter means 30, and power-supply means 32 for indicating loosening. According to one embodiment, the transmitter means 30 can be of a wireless type. According to one embodiment, the detector means can be of a type that measures rotation or distance. All of these can be implemented with several different constructions, as will be described in the following as embodiments of the invention.

Figures 2 and 3a show some first embodiments of the indicator according to the invention in individual attachments. In these embodiments, the indicator is formed from basic structures, which include among others a locking plate 17, a base locking plate 44, and tension springs 12 arranged between them. The locking plate 17 and the base locking plate 44 have one or more attachment points 61, 21 for the tension springs' 12, suitably arranged relative to each other. The attachment points can be, as shown in Figure 2 and 3a, for example, holes 60. The holes 60 are arranged in axial flange points 21, 61 made in the plates 17, 44. In connection with both ends of the tension springs 12, there can be an end loop 130, which can be fitted into the hole 61.

The material of the locking plate 17 can be, for example, RST steel, with a thickness of, for example, 2 - 5 mm. A hole is arranged in the plate 17 for the nut. On the internal circumference of the hole, there is toothing according to the wrench size of the nut, for the counter-surfaces of the outer circumference of the nut. The wrench size, toothing spacing, and the type of attachment in general can be selected freely. In the embodiment, the locking plate has a slightly oval shape. There are holes in its narrowing ends, in which a protective cap (not shown) for the nut can be set.

The material and thickness of the base locking plate 44 can correspond to those of the locking plate 17. It can also have holes arranged at appropriate points, the significance of which will be examined in greater detail later.

The tension spring 12 can be, for example, a spiral spring or a conical spring, which has a sufficiently great spring force. The spring force is preferably such that the tension spring 12 also creates a slight braking force effect on the loosening of the nut, and perhaps even tightens it.

The locking plate 17 lies around the nut/bolt being secured/monitored, in such a way that the tension springs 12 are in tension, when viewed towards the base locking plate 44. The tension acts in a direction tightening the nut/bolt.

According to one embodiment, the rotation detector 31 can include first detecting elements 31.1 arranged in connection with the nut 9, and second detecting elements 31.2 arranged in connection with the base structures of the attachment location. The second detecting elements 31.2 are arranged as a counter- pair to the said first detecting elements 31.1. Also the nut 9 itself, the spring 12, and/or also the base structures can naturally form a detecting element in itself. The rotation detector 31 can, according to a first embodiment, be arranged to operate mechanically.

Figures 3a and 3b show an example of a nut protector 36. This can be used to prevent the dirtying of the attachment point and the detecting elements 31.1, 31.2 of the indicator, more generally, of the rotation detector 31, which might otherwise cause problems with the operation of the indicator. In the case embodiment, not only the nut protector 36, but also the power supply 30 of the detector 31.1, 31.2 and the transmitter 30, as well as the transmitter 32 itself, are in connection with the nut protector 36. In this case, the transmitter 30, along with the power supply 30 of the transmitter 30 and the detector sensor 31 are thus integrated as a single component. This for its part shows that the system according to the invention can be assembled, not only from individual components, but also from modular totalities, in which different functionalities are integrated. Besides battery technologies, static electricity and methods of charging from motion can also be used as the power supply, in which connection reference is made, for example, to technologies known from wristwatches . Fuel cells are also possible.

The nut protector 36 can be attached, for example, to with the base locking plate 44. There are hooks 150 for this purpose in the nut protector 36 and holes 45 fitting the hooks 150 in the base locking plate 44. Leads 37 to the detector 31.1, 31.2 run in the nut protector 36. The detector element 31.2 can be attached to the base locking plate 44. Thus, there can be a connector 62 in the element 31.2, by means of which the leads 37 are connected to the detector element 31.2.

According to a second embodiment, selected parts of the battery 32, the transmitter unit 30, and the detector unit 31.1, 31.2 can be also installed in the base locking plate 44 and the locking plate 17, or even inside the tension springs 13, or in some other suitable manner. Thus, there are no restrictions on their location within the indicator.

The rotation detector 31 in connection with the locking plate 17 and its base locking plate 44 in the indicator arrangement is formed, for example, of counter contact pieces 31.1, 31.2, more generally, of switch-making pieces. They can be radially on the same radius, for example, when examined relative to the axis of the nut. There can be several contact pieces 31.1, 31.2 in the plates 17, 44. Thus, one contact piece 31.1 can be in the locking plate 17 in connection with the nut while its counter pair 31.2 is, for example, in the base locking plate 44. Figure 2 shows an example of exactly just such an embodi- ment . In it, the nut is closed in such a way that the contact pieces 31.1 in the locking plate 17 are not next to the contact pieces 31.2 in the base locking plate 44 and thus are not in contact. Figure 3a shows a situation, in which the nut has become loose. The contact pieces 31.1, 31.2 are now next to each other and thus in contact with each other. This switches on the power circuit and leads to the indication of the loosening of the nut. For reasons of clarity, the contact pieces 31.1, 31.2 are shown separate from each other in Figure 3a.

It will be obvious to one versed in the art that the detection of loosening can also be arranged in such a way that loosening is detected from the success of the contact of the contact pieces 31.1, 31.2, i.e. using the opposite arrangement to that described above. In this case, when the nut is tight, the contact pieces 31.1, 31.2 are in contact with each other and when the nut loosens they lose contact with each other.

Further, when applying the contact pieces 31.1, 31.2, physi- cally contact-free applications are also possible. It is then possible to refer to a Airtual' contact / lack of contact, in which a galvanic connection is not formed at all. In such an application, the similar/opposite polarities of magnets can be applied, for example. If loosening occurs, a change of polarity of the magnets 31.1, 31.2 relative to each other is detected. On its basis, an alarm can be given of a change in the state of the nut 9.

The loosening indicator can also include one or more spring elements 12. They can be arranged to prevent the nut/bolt 9 from loosening. The rotation detector 31 can then be arranged in connection with the spring elements 12.

Figure 1 shows yet another example of a location embodiment of the indicators. In it, the detector elements 31.1, 31.2 forming the rotation detector 31, as well as the transmitter unit 30 and the power supply 32 are installed inside the tension springs 12. They can be integrated at least partly in a single component. The rotation detector 31 can be formed from electri- cal component.

The detector 31.1, 31.2 fitted inside the tension spring 12 sends a warning of a loosened bolt and of a consequently possibly detaching wheel, if the spring 12 has been stretched from its initial position. Alternatively, a warning can also be set to be sent, if the spring 12 shortens too much. When the transmitter 30 and the detector 31.1, 31.2 are inside the spring 12, it may be necessary for there- to be a protector 33 around the spring 12. The protector 33 protects the components 30, 31, 32 from dirt and moisture and other possible detrimental factors.

In this case, the detector 31.1, 31.2 can be based, for example, on a change in resistance or capacitance, or in some other suitable electrical variable, or on a phenomenon that can be defined from an electrical variable. In that case, the detector unit 31.1, 31.2 can be, for example of a type in which one part is pushed inside the other, which creates a change in the relevant electrical variable when the length of the tension spring 12 changes, and consequently an indication of a change of state in the attachment point. On the other hand, in this case too, contact-type application analogies are possible, as was already described in the previous embodiment. The rotation indicator sensors 31 can also apply nano-technology/electro- nics . On the other hand, the spring 12 itself too can surprisingly form the detecting element. In this case, if the spring 12 is set to tighten the nut 9, its spring loops can make mutual contact in a set way. When the spring 12 stretches, the contact between the loops vanishes, creating an indication of the nut 9 loosening. Further, a suitable Alarm wire' can also be arranged in the spring 12. The wire is intact when the nut is at the tightness set for it. If the nut 9 begins to loosen, the spring 12 stretches and consequently the Alarm wire' breaks. The power circuit of the detector circuit is then broken, which triggers an alarm.

Further, according to a more highly developed application, a change in, for example, some electrically measurable variable can be defined from the spring 12, which is caused, for example, by a change due to loosening in the state of tension of the spring 12. One example of this is the resonance frequency of the spring 12. On the basis of this, it is possible to determine the loading (length) of the spring 12 and to indicate the loosening of the attachment point 9, 9', which can be defined from the change in the variable and forwarded by the transmitter means 30. Thus, surprisingly even the spring 12 itself can act as a detector. Methods used to weigh the loads of cranes and hoists can also be applied.

Figure 12 shows one example of an arrangement according to the invention. In it, a transmitter unit 30, which is now a wireless transmitter, is set to transmit data on a loosened joint to a set recipient, who has a receiver 70, 72, 73 for a wireless notification of loosening.

The data transfer between the transmitter 30 and the receiver 70, 72, 73 can take place, for example, using a wireless local- area network connection, such as a WLAN network, a Bluetooth network, or by exploiting other free radio resources, for example, the 400 MHX (440 MHz) frequency band. Fixed data transmission networks can also be applied such as, for example, the control buses used in industrial plants. Several different ways can be applied to transmit the notification. It can be made, for example, in the form of a warning light to a control room, such as the cab 72 of a truck. The vehicle's own data network (CAN) can also be utilized. Also, the notification directed to mobile phone 70 or onboard computer, is possible. Further examples of selected entities to whom notification can be made in an established manner include repair shops 73, service agencies, foremen, and various data and operation control systems. In order to transfer data to these, various mobile communications technologies, for example, can be utilized, such as GSM technology or 3-G technology 74. The receiving entities and data-transfer methods in no way restrict the scope of protection for the invention.

A notification of a loosened bolt can be sent, for example, using a defined frequency or in some other way. Free radio frequencies, such as those provided for PMR communications, can be applied for this. Using a radio network 75 of this kind, information of a loosened bolt is received, for example, in the cab 72 of the truck. On the basis of the frequency, the loosened bolt 9, 9" can then be identified, if an individual frequency is set for each attachment point. Naturally, more highly developed technologies are also possible. Each attachment point can then be equipped with its own identifying address, for example, an IP address, from which the loosened bolt 9, 9' can be identified.

Notification of a loosened bolt 9 can also be transmitted, for example, to a receiver in the vehicle, such as an onboard computer, from which it can be forwarded and processed in many different ways. A state indication can be displayed in the vehicle's cab 72, using the aforementioned warning lights and/or mobile communications technology can also be used to forward it to a remote monitoring station, for example, is a service repair shop 73.

On the other hand, in the attachment point itself can already incorporate a transmitter module applying a wireless mobile communications network, such as a GPRS modem 71, by means of which information on a loosened bolt can be transmitted directly to a set mobile station 70, for example, as an SMS message. Such an embodiment is shown by the oil/gas pipeline 100 depicted in Figure 12. In this case, battery/solare panel technology 76 can be utilized as the power supply of the GPRS modem 71 and the rotation detector 31, thus allowing the indicator to be arranged even in areas in which electricity is otherwise not available. If problems arise in the power supply, for example, when the battery's capacity runs out, a wireless notification of this, for example, or a corresponding signal is sent to the service unit. Rotating elements are a particularly advantageous application for wireless indication. In them, it is extremely difficult to arrange data-transfer links over cables .

Monitoring of the attachment point can take place either as a continuous process, or alternatively only from a separate command. Thus, a query concerning the state data, i.e. the tightness/looseness, of the attachment point can be sent to the monitored point. The embodiment saves power in the monitored point.

According to one surprising embodiment, status queries of this kind can also be applied to the creation of the power required by the indicator, even without any special battery arrangements. In such an embodiment, the power can also be created by applying inductive methods, for example, RFID technology, or even more particularly an external excitation. Some other similar methods based on RFID technology are sensors based on backscattering and two-way sensor. In these cases, a more general reference can be made to energy transmitted with the aid of an electromagnetic field.

When applying RFID technology, there is a receiver-transmitter pair in connection with the indicator. In one embodiment, part of the energy radiated by the reader device is used for the power supply of the indicator itself. In the case of external excitation, for example, a status query sent wirelessly by the monitoring system causes the antenna of the receiver connected to the indicator to form a changing electrical field in a coil formed by it. In the indicator's transmitter, there is also a coil loop, which is set sufficiently close to the coil formed by the antenna for power to be induced in it as a result of a status query. An electric field is induced in the coil formed by the antenna by periodically changing the direction of travel of the current in the coil. In principle, the coils of the antenna and the indicator form a transformer. The power created allows the indicator to read its detector and reply to the status query. Thus, the power supply means too can be imple- mented in several different embodiments, with the queries then taking place using external excitation.

The base locking plate 44 can be attached in numerous different ways to the base frame structures of an installing point including an individual nut attachment. According to one example of an application, the plate 44 can be attached to the body of the attachment point (for example, to a rim) by drilling holes next to the retainers 63, or by screwing or welding or in some other way. Roughening or bevelling 29 can be in the lower surface of the base locking plate 44, as described in the Figure 4. Knurling 29 can also be used to hold the base locking plate 44 in place, so that the plate 44 will not move, despite the possible tightening force of the tension springs 12. Figures 5a - 5e show a second embodiment of the indicator according to the invention. Besides the nut/bolt loosening indicator being intended to be remotely monitored with the aid of a transmitter 30 (to the driver, repair shop, service agency, foreman, data system, or mobile telephone, etc.), it is also further possible to arrange an indicator function that can be detected visually by eye. This achieves an advantage, for example, when the service personnel are working close to the attachment points 9, 9', without a wireless monitoring func- tionality.

Besides the invention being able to be applied as a loosening indicator, it can also be used, for example, as a rotation guard and revolution counter, as well as a temperature sensor (for, example, to monitor bearings) . If the loading of the application point changes, the state change is detected / an alarm can be given of a reduced speed of rotation.

Figures 5a and 5b show in greater detail one example of a visual indicator arranged in an indicator according to the invention and of a second possible implementation of a rotation detector. In this embodiment, the indicator according to the invention is formed, in main principle, of two casing structure totalities arranged at least partly coaxially inside each other.

The inner of these totalities is a hexagonal nut cap 6 in connection with a nut 9 threaded onto a shaft 8. The outermost component that encloses the hexagonal nut cap 6 is a protective dome 7, which can be of a plastic material, for example.

In the outer jacket of the hexagonal nut cap 6 there are, for example, guide elements 14, which protrude radially from it. There are counter elements to the guide elements 14, in the inner jacket of the protective dome 7. The guide elements 14 are allowed to move freely radially inside its counter ele- ents, but their axial movement and thus axial movement between the hexagonal nut cap 6 and the protective dome 7 is prevented. As a result, thanks to the guides 14, the hexagonal nut hat 6 remains firmly together with the protector 7 and is centred in the protector 7.

The guide and counter elements 14 can also be replaced with opposing connector surfaces. In that case, there are elements at the nut end of the hexagonal nut cap 6 for preventing the axial movement of the cap 6 (not shown) .

Further, at the end of the nut cap 6 opposite to the end at which the shaft 8 enters it, there are one or more metal strips 3. The metal strips 3 protrude at an angle axially outwards from the end of the nut cap 6. For the strips 3, the end of the protective dome 7 includes, for example, contact surfaces or detector studs 2, arranged in sectors. The surfaces or studs 2 are arranged in the protective dome 7 in such a way that they can be in contact with the metal strips 3, when their positions relative to each other is as desired.

In the installation stage, the protective dome 7 can be set on top of the nut cap 6, in such a way that the detector studs 2 and the metal strips 3 are in different positions . When opening rotation takes place in the nut 9, the metal strips 3 rotate radially along with the nut cap 6 and, as a result, end up in contact with the detector studs 2, thus creating a connection that indicates loosening.

Figures 5c and 5d depict more detail of the visual indicator 1 arranged in this embodiment. It should be stated in general, that the means for permitting a visual loosening indication includes at least one element 111 arranged to rotate along with the nut/bolt 9. The indicator 1 can be formed of different colour zones 110, 120 and of circular discs 111, 59 arranged axially relative to each other. At least some of these can be of a type that rotates radially along with the nut/bolt 9 while some are fixed in place. In this embodiment, the visual indicator 1 operates on the principle that the nut cap 6 is connected with the visual indicator 1. The connection can be made, for example, using a shaft 13 (Figure 5a) .

At one end, the shaft 13 is fixed to the nut cap 6, for example, in connection with the closed end opposite to that with the nut 9. In connection with the opposite end, the shaft 13 is fixed in the indicator disc 111, for example, at its centre point 13'.

The indicator disc 111 can be arranged to rotate radially in the protective dome 7. Part of the area 110 of the disc 111 can be coloured, for example, red and part of the area 120 green, thus indicating the state of tightness of the nut 9 on the shaft 8. In the disc 111, the areas 110, 120 can be evenly divided to be four, two of which are red and two green. The areas 110, 120 are, for example, in sectors at 90-degree intervals and entirely cover these sectors 110, 120.

At least part of the upper end of the protective dome 7 can be transparent. In the embodiment of Figure 5d, there are two 45- degree transparent sector areas, which are opposite each other. In addition, in the dome 7, there are two non-transparent sector areas 59, which can also be opposite the 45-degree sectors. The use of such an arrangement achieves a particularly illustrative way of indicating the state of tightness of the nut 9. The driver need not even stop next to the nuts when checking the nuts 9 of his vehicle, but can see immediately from the colour contrasts, if the nuts 9 of some wheel can be construed as having loosened.

Further, the colour zones 110, 120 and the contact studs 2 of the dome 7 are aligned suitably relative to each other. If the red sector area 110 is set to signify a loosened attachment, then the detector studs 2 and the red sector areas 110 of the disc 111 are set suitably in the corresponding radial points, so that when a contact indicating loosening is formed, the visual indicator 1 will also notify the loosening of the nut 9.

When setting the protective dome 7 in place, the disc 111 is set in such a way that its green areas 120 are in the transparent sector areas of the protective dome 7. The visibility of the green areas 120 indicates the presence of a secure attach- ment. If the nut 9 has loosened on its shaft 8, the red area 110 of the disc 111 will become visible in the transparent sector area of the protective dome 7, indicating an insecure attachment. In that case, the green sector areas 120 are correspondingly hidden beneath the partly non-transparent sectors of the end disc 59. Naturally, there are also other possible ways of arranging the colour zones. In addition to these, indications of the degree of loosening, i.e. rotation of the nut 9, 9' can also be arranged.

The attachment of the nut protector 7 to the base at the point of use, for example to a rim, can be take place, for example, using a magnet 10 or a locking base plate 44, or in some other manner. There can, for example, be knurling in the magnetic ring 10 or some other machining that increases adhesion, which will facilitate the removal of the protective dome 7. Neodymium magnets, which have an extremely strong grip on their base can, for example, be used as the magnets 10. Other (super) magnets can also be used. The use of a magnetic attachment achieves yet another advantage in that a possibly fractured bolt will be retained at the attachment point. This is important, for example, in paper machine technology or similar, in which a fractured bolt may damage the machine structures, if it escapes without retention from the attachment point, when it fractures.

If the installation location occurs lack of space, the indicator can be made smaller or otherwise shaped to fit the instal- lation location better. One example of such a cramped installation location is the rim of a drive wheel, where the wheel hub may come close to the bolts. Another way to fit the indicator in place in such a cramped installation location is to arrange it to be shaped as a partial circle (Figure 10b) . In that case, the magnet 10, for example, can be formed from two pieces, or can be, along with the body of the indicator, shaped as a partial circle (not shown) .

In the embodiment of Figures 5a - 5e, the transmitter, the detector stud 2 acting as the counter surface to the detector elements, and the power supply 5 can all be attached to the protector 7 or to the nut cap 6. In the nut protector 7, there can also be a solar panel (sticker) acting as the power supply, which can be, for example, in connection with the bolt 9.

In this embodiment too, the transmitter unit 5 can transmit notification of the loosening of the attachment to a data network 74, 75, to a mobile telephone 70, to a warning light in the cab 72, etc. The notification can also be sent wirelessly. Besides loosening, information on other state data can also be sent, for example, on movement that has stopped, and on rotation. A temperature sensor 15 and its transmitter 16 can also be part of the arrangement. They can be located, for example, in connection with the magnetic attachment 10, from where a possible rise in temperature, for example in the bearings, can be detected immediately. In connection with the tyres of a vehicle, it is also possible to apply a tyre pressure indicator connected to the valve, the state data of which can also be sent wirelessly.

The loosening indicator can also be applied to the calculation of revolutions. Calculation of revolutions then takes place, for example, when the metal strip 3 and the studs 2, or other kinds of contact surfaces make contact with each other, notifying a state of rotation, or even the number of revolu- tions wirelessly to the recipient of the information. In this case too, temperature monitoring can be applied.

Figure 5e shows one example of a receiver, which is located, for example, in the cab 72 of a truck. The receiver 15 can be a modular component that is, as such, known, in which a customer-specific frequency is applied. This can be used to identify directly the monitoring object that has given the alarm/state notification.

Figure 6 shows a third embodiment of the invention. In this embodiment, it is possible to monitor the temperature of the monitoring object, for example, a bearing 41. If the temperature of the bearing 41 carried in the bracket 39 rises, the heat is conducted to the detector and transmitter 15, 16 at the end of the axle 40. In addition, this construction can also be used to monitor the number of revolutions, for example, according to the principle disclosed in the previous embodiment, and its changes according to the loading. As was already described previously, the monitoring of the rotation state and/or the number of revolutions can take place, for example, with the aid of the contact between metal strips 3 and studs 2, or other kinds of surfaces, or in some other way. In this case, the construction is attached, for example, with a magnet 10 to the bracket 39.

The inset in Figure 6 also shows one alternative type of magnetic attachment 10. In it, for example, in the bracket 39, there can be a stud or corresponding screw 91 and an opening 93 in the protective dome 7 equipped with a groove 92. The material of the stud or screw 91 can be, for example, metal, aluminium, or plastic. The size of the opening 93 is arranged to be such that the widened head of the stud 91 can pass through it. The size of the groove 92 is arranged to be such that the body of the stud 91 can move in the groove, but that the widened head of the stud 91 cannot pass through the groove 92. The indicator is set in place in such a way that the widened heads of the studs 91 protrude from the openings 93 of the groove openings 92, 93 made in the circumference of the protective dome 7. After this, the indicator is rotated radially, so that the widened heads of . the studs 91 move over the grooves, which prevent the indicator from separating from the installation location. The bracket 39 can equally well be considered to be the wheel rim of the vehicle. The stud/screw attachment arrangement can be retrofitted, or it can also be made during the manufacture of the rim.

Figures 7a and 7b shows a fourth embodiment. In it, there is a hole 51, in which there is a bolt 65, in the centre of the axle 40 mounted in the bearing 41. The axle 40 runs through the bracket 39, which bracket 39, acting as an attachment base, can be of, for example, plastic. In this embodiment, a hollow plastic bolt 38 is placed on top of the bolt 65. Inside it, or generally in connection with it there can be a transmitter unit 30', rotation detection elements 31', and a power supply 32. There can also be a temperature sensor in connection with the cover 23 covering the plastic bolt 38, in which the transmitter / power supply can also be situated. In connection with the cover 23 of the indicator, there can also be a detector element 31.2, in which case its counter-piece 31.1 can be in the end of the plastic bolt 38. In addition, there can be a temperature sensor 66 in the middle of the bracket 39 on the underside of the bolt 65.

Figure 8 shows an embodiment corresponding to that of Figure 7. In this case, the bracket 39 is, however, arranged to be thick enough for the electronics belonging to the indicator to be arranged inside it, and thus protected from impacts. The material of the bracket 39 can be, for example, plastic. The cover 23 is now, as it were, set into the bracket 39. In vehicles, for instance, wheel trim can be utilized in place of the bracket 39. Without the power supply or even with the power supply, the indicator can be integrated in the trim, according to the distribution of the bolts/nuts. Its installation will then be particularly easy to carry out in connection with the installation of the trim while at the same time the indicator will also be protected. The quality of the wireless connection will also improve, because the transmitter is no longer in the rim recess. The wheel-trim application is shown in greater detail in Figures 15a and 15b.

Figures 9a and 9b show yet a sixth embodiment of the indicator according to the invention. This can be applied, for example, in industrial fastenings and there particularly in individual bolt attachments, however, without excluding other applications .

The radio transmitter 30 and the battery 32 can be located quite freely. They can be, for example, in connection with the nut protector 23, in the locking plate 17, or in a base plate 48. There can be knurling or other patterns on the underside of the base plate 49. A retainer pin 49 can be bent from the base plate 48 and set in a hole drilled in the base 67. The base plate 48 can also be welded, or otherwise attached to the metal .

According to one embodiment, two washers on top of each other, with wedge toothing locking the joint, can also be applied in the base plate 48. One commercial example of this is the Nord- Lock fastening system. In the case of the washers on top of each other, the fastening is based on exploiting the pre- tensioning of the joint. A second alternative method is based on the disclock system. When utilizing pre-tensioning, or in other cases too, precision sensors known from anemometers, for example, can be applied. These can be used to detect the amount of loosening in degrees, for instance. Figure 9b shows an example of such an embodiment based on the pre-tensioning of the joint, in connection with a bolt 9'. In it, the bodies of the washers are shown with the reference numbers 200, 201. The indicator component 202 is now between the washers 200, 201. There are connector surfaces 203, between the indicator component 202 and the washers 200, 201, which are suitably arranged to cover the opposing surfaces of the washers 200, 201, in such a way that a contact / lack of contact is created as a result of loosening and a notification is subse- quently given of the loosening of the joint.

Nano-electronics/technology can also be applied in the case of a locking element 200, 201 based on the pre-tensioning of the joint. Besides the opening rotation of the joint, it is also possible to monitor strain in the bolt, the alignment of the surfaces, and thermal expansion/contraction. In addition to the washers 200, 201, nano-electronics/technology can also be applied in the bolts/nuts (smart materials) . The indicator can be activated, for example, by electricity, after the tightening of the joint.

The detecting elements 31.1, 31.2 forming the indicator sensor 31 can be attached, for example, using adhesive tape. They can be arranged according to a principle similar to that in the case disclosed above. Thus, when the nut 9 is tight, the detecting elements 31.1, 31.2 are not next to each other. If the nut 9 loosens, the detectors 31.1, 31.2 move next to each other. This triggers the radio transmitter 30 to make a transmission, which is transmitted, for example, wirelessly to the monitoring point. In this embodiment, there are two tension springs 12 on opposite sides, between the base plate 48 and the locking plate 17, which also tighten the nut 9. The figure does not show the leads between the detector 31.1, 31.2 and the transmitter unit 30. These can be arranged in several different ways. Figures 10a and 10b show yet another embodiment. In it, the alarm transmission is switched by magnets 31.1', 31.2'. When the magnets 31.1', 31.2' are in the correct position relative to each other, an alarm is given. A ring magnet 52 is used to hold the transmitter protector 50 firmly on the attachment base, for example, on the vehicle's wheel rim 54. The magnet 52 can be completely circular, or its circumference can be cut in a straight line, to fit the indicator into cramped applications .

On top of the nut cap 23, there is a magnet 31.2'. Its counter- pair 31.1' is inside the protector 50 of the transmitter 30. The transmitter 30 and the power supply 32 are tightly encased on top of the protector 50. There can also be a sealing element or similar (not shown) between the transmitter protector 50 and the rim 54, more generally in connection with the case structure of the indicator and the basic structures of its attachment point. One example of this is a rubber washer / O-ring. One task of the seal is to prevent moisture and fluid from entering the indicator. In addition, it can also be of a pressure-resistant type. This is important not only in vehicle tyre applications, but also, for example, in the process industry, where masses, moisture, and dirt can interfere with the functioning of the indicator.

The embodiment operates as follows. If, when the nut loosens, the magnet 31.1' of the nut cap 23 aligns with the magnet 31.2' of the transmitter 30, the transmitter 30 is switched to transmit an alarm signal to the monitoring centre, cabin, data network, or in general to a set destination 70, 72, 73. In the triggering of the detector/transmitter, a reed relay, for example, or some other suitable technology can be applied. In the protective case 50, there can also be, for example, a LED 53, which visually displays the state of tightness of the nut. According to Figure 11, a panel 55, showing all the wheels of a full-trailer combination, can be installed in the cab of the vehicle or a similar monitoring location. When an alarm is received, it is also possible to see which wheel is affected. This is because the transmitters 32 can be coded in a known manner.

Figures 13a and 13b show some indicator solutions applied to cross-head/Allen screw applications. The arrangement according to the invention is suitable for all sizes of wrench and all types of bolts/nuts (Allen, hex head, cross-recess, cross- head, Torx, etc.). Depending on the type of joint, there is counter-piece 94 fitting the type of bolt/nut 9'' in the indicator. Figure 13a shows a solution applying a spring 12. In it, a 12-sided sleeved counter-piece 94 can be set in an Allen bolt head 95. Further, the hexagonal sleeve 94 can be fitted to an oval plate 96, at the ends of which there are openings 60 for springs 12. The plate 96 and the sleeve 94 can be formed from a cast piece or can be welded together to form a unified piece. On the other hand, the plate 96 can also be pressed. There will then be a hole made at the location of the sleeve 94, the pressed edges of which are turned down to form the sleeve 94. The springs 12 can be as shown in Figures 2 and 3a. On the other hand, the indicators according to the invention, independent of the embodiment, can also form a linked, annular arrangement, such as is disclosed in the WO publication referred to at the beginning of this application, in which it appears in Figure 3.

In Figure 13b, the hex head application is shown in an indicator according to Figure 5a, the operating principles of which need not be referred to again in detail in this connection.

Figures 14a and 14b show some indicator solutions when the attachments are recessed. One such embodiment is, for example, in connection with aluminium or light-alloy rims 97. In this case the body of the indicator can be formed of simply a hex- nut cap 6. The internal shape of the hex-nut cap 6 can, for example, fit so tightly that it will remain attached to the nut 9 when the indicator is pressed onto the nut 9. On the other hand, a magnetic attachment 98 can also be applied. In that case, the magnet 98 can be, for example, inside the hex-nut cap 6.

There can be one or more connector pieces 31.1 on the outer circumference of the hex-nut cap 6. Counter-pieces 31.2 can be arranged for them in several different ways. In the embodiment of Figure 14a, the pieces 31.2 are inside the nut recess while in the case according to Figure 14b they are outside the nut recess. For example, the connector pieces 31.1, 31.2 can be attached using a sticker or glue. A drilled attachment is also possible. The connector pieces 31.2 can be attached to the rim already during its manufacturing stage.

Figures 15a and 15b show one example of a wheel-trim applica- tion, viewed from different directions. Figure 15b shows a cross-section of the rim 163 and of the wheel trim 160 and indicator in connection with it. The indicator application is described in greater detail with reference to the insets of Figure 15b. An indicator for each bolt 9'' is integrated with the wheel trim 160, according to the distribution of the bolts. On the other hand, the indicator can be attached to each bolt applying the principles referred to above. The wheel trim 160 must then be dimensioned in such a way that it can be set in place, despite the indicators.

The indicator includes a socket 162 to be fitted to the bolt 9'', which can be, for example, twelve-sided. The socket 162 can also be equipped with a ratchet mechanism, which can be the arrangement even in several locations. The socket 162 can move axially relative to the basic body 164 of the indicator. The movement is limited by the spring 166 shown in the inset showing the socket 162 and the basic body 164 in greater detail. The inset also shows one example of the possible location of the ratchet mechanism 180. The reference number 181 shows a support ring.

At the end on the wheel trim 160 side, there can be support plates 165.1, 165.2 on both sides of the trim and bearings in connection with them, by means of which the indicator is securely attached, but nevertheless in such a way as to permit the indicator function, i.e. rotation of the nut 9'' if it possibly loosens. The support plates 165.1, 165.2 can also include a possible visual indication of the state of tightness, in which the colour applications 110, 120 already described in Figures 5a - 5e can be applied. There can also be counter- pieces in the support plates 165.1, 165.2, such as, for example, holes 161 for a tool, by means of which the socket 162 can be rotated radially. In order to permit rotation, the arrangement is equipped with radial grooves 110, 120. An application without grooves is also possible, in which case twigs and branches, for example, will not catch in the grooves. The tool can have, for example, two studs, one example of which is a device like the disc key found in angle grinders (not shown) . There can also be axial protrusions 182 in the support plate 165.1, for manual rotation.

The detector 31 detecting loosening can be of a solution that is, for example, one that has already been described above. The detector 31, the transmitter 30, and the power supply 32 can be, for example, in the body of the wheel trim 160. It is sufficient to say that the wheel-trim arrangement can be installed in place surprisingly easily with the aid of the construction. As is known, when setting wheel trim 160 in place, the sockets 162 are not necessarily in such positions that they will fit straight onto the nuts 9''. The sockets 162 must then be permitted a short axial movement, which is caused by the nut 9'' and which is directed towards the wheel trim 160. Each socket 162 can be rotated radially using a tool that fits into the counter recesses 161. The rotation causes the polygonal internal circumference of the sockets 162 to rotate to such a position, that they fit onto the nuts 9''. Once the 5 socket 162 has been set in position, the force of the spring 164 presses the socket 162 onto the nut 9''.

As was already stated above, the wheel-trim arrangement can also be implemented as a so-called ratchet model. In that case, 10 the wheel trim 160 and the indicator need not be detached at all, for example, while tightening the bolt 9''.

Figures 16a and 16b shows still further examples of the application of different types of detector. In both applica-

15 tions, the sensor electronics are arranged inside the bolt tightening spring 12. Figure 16a shows a piezoelectric sensor implementation. The piezo crystal 172 can be attached in some way to the spring 12. In addition, the piezo crystal 171 is connected to the circuit board 170 through a pressure spring

20 173. The circuit board 170 can be further stabilized by a circuit-board holder 171 in connection with one or other end of the spring 12. The holder 171 keeps the circuit board 170 in place during changes in the length of the spring 12. When the nut loosens, the length of the tension spring 12 changes. This

25 causes a change in the force acting in the piezo crystal 172 from the pressure spring 173. As a result, the resistance of the crystal 172 changes and the strain in the tension spring 12 can be detected. The force is transmitted to the piezo 172 by a mechanical transmission piece 177 connected to the spring

30 173, the other end of which is connected to the tension spring 12. When the length of the spring 12 changes, the mechanical transmission piece 177 either presses the pressure spring 173 against the piezo crystal 172, or releases the pressure against the crystal 172.

35 Figure 16b shows a strain gauge solution. The strain gauge 174 is attached, for example, directly from its ends to the spring 12. There are leads 175 from the strain gauge 174 to the circuit board 170. When the length of the tension spring 12 changes, the length of the strain gauge 174 also changes. The strain in the tension spring 12, which is in turn proportional to the loosening of the nut, can then be detected. The strain gauge and piezo implementations can, of course, be arranged in other ways in the indicator, even without the spring 12.

It must be understood that the above description and the related figures are only intended to illustrate the present invention. The invention is thus in no way restricted to only the embodiments disclosed or stated in the Claims, but many different variations and adaptations of the invention, which are possible within the scope on the inventive idea defined in the accompanying Claims, will be obvious to one versed in the art .

Claims

1. A loosening indicator for a nut/bolt (9), which is an indicator device to be installed in connection with the nut/bolt (9), characterized in that the indicator device includes detector means (31, 31') for detecting the loosening of the nut/bolt (9), transmitter means (30), and power supply means (32) for indicating the loosening.

2. A loosening indicator according to Claim 1, characterized in that the transmitter means includes a wireless transmitter (30) .

3. A loosening indicator according to Claim 1 or 2, character- ized in that the detector means (31, 31') include first detecting elements (3, 31.1, 31.1') fitted in connection with the nut (9) and second detecting elements (2, 31.2, 31.2') arranged in connection with the basic structures (39, 54, 67) of the attachment location, which are arranged as a counter- pair to the said first detecting elements (3, 31.1, 31.1') .

4. A loosening indicator according to any of Claims 1 - 3, which include one or more spring elements (12), which are preferably arranged to restrain the nut/bolt (9) from loosen- ing, characterized in that the detector means (31) are arranged in connection with the spring elements (12).

5. A loosening indicator according to any of Claims 1 - 4, characterized in that elements (13, 59, 110, 111, 120) are fitted to the indicator to permit a visual indication of loosening.

6. A loosening indicator according to any of Claims 1 - 5, characterized in that the detector means are of a type suitable for determining an angle or a distance.

7. A loosening indicator according to any of Claims 1 - 6, characterized in that the detector means (31, 31') include components, which are selected from the group of magnetic sensors (31.1', 31.2'), piezoelectric sensors (172), and/or strain gauge transducers (174).

8. A loosening indicator according to any of Claims 1 - 7, characterized in that the indicator is formed of two casing structures (6, 7, 23, 38, 50) fitted at least partly coaxially inside each other.

9. A loosening indicator according to any of Claims 1 - 8, characterized in that the indicator (202, 203) is arranged in connection with a locking element (200, 201) based on the pre- tensioning of the joint.

10. A loosening indicator according to any of Claims 1 - 9, characterized in that the indicator can be fitted in connection with wheel trim (160) .

11. A loosening indicator according to any of Claims 1 - 10, characterized in that the power supply means are arranged to create the power required by the indicator device from the external excitation.

12. A system for indicating the loosening of a bolt/nut (9), which system includes an indicator device to be fitted in connection with the nut/bolt. (9), characterized in that the indicator device includes detector means (31, 31') for detect- ing the loosening, transmitter means (30, 71) , and power supply means (32), as well as receiver means (70, 72, 73) for indicating the loosening.

13. A system according to Claim 12, characterized in that the data transfer between the transmitter (30) and the receiver (70, 72) is arranged to take place preferably using a wireless data communications network link, for example, a WLAN network, a Bluetooth network, or free radio frequencies, such as the 400 MHz band, or using RFID technology.