TITLE

SYSTEM FOR MONITORING AN INSULATED RAIL JOINT

DESCRIPTION

TECHNICAL FIELD

The invention relates to a system for monitoring an insulated rail j oint .

BACKGROUND

Insulated rail j oints are commonly used in railway networks to galvanically separate two rail sections of a rail track . I f a train-wheel passes over from one rail section to the other rail section, wherein the two rail sections are separated by the insulated j oint , a signaling is generated and used in a signal box of a railway operator to track and check the position of the train on a rail network . To enable this galvanic separation, such insulated rail j oints ( in addition to other measures ) have insulating shims between the ends of the rail sections , i . e . , the insulating shims are located where the rails meet each other . This insulating shim, as well as the entire insulated rail j oint , is therefore exposed to high loads from trains traveling over the rails and the environment .

This leads to wear of the insulated rail j oint , in particular of the insulating shim, so that the insulated rail j oints must be checked regularly and replaced i f necessary . I f damage to the insulated rail j oints is not detected early enough, the signaling to the signal box may lead to an incorrect information regarding rail track occupancy, which in turn may lead to an interruption of train traf fic due to safety considerations . In the past , two approaches have become established to check the insulated rail j oints . The first approach involves workers using mobile measuring devices to visit the insulated rail j oints and examine them for damage , which is for example disclosed in US 1765715A. The second approach includes special measuring trains that carry mobile measuring devices that check the rails and thus also the insulated rail j oints for degradation, which is for example disclosed in DE102018219256A1 .

Each approach has its individual disadvantage . The first approach is labor intense and requires special safety measures which hinder regular rail traf fic . The second approach requires special train equipment and degradation of the insolated j oint can only be detected while the train passes over such a j oint with relatively low speed, which in turn also hinders regular rail traf fic . In the past , this has meant that the insulated rail j oints were checked less often than it was necessary in order to reliably detect damage at an early stage .

Therefore , the obj ect of the invention is to provide a system for monitoring an insulated rail j oint that overcomes the problems mentioned above .

SUMMARY OF THE INVENTION

This obj ect is achieved by a system according to claim 1 . Therefore , the subj ect matter of the invention is a system for monitoring a state of an insulated rail j oint characteri zed in that the system is designed for the stationary operation directly at the permanent way, preferably at the track, and the system is designed such that a train can pass the insulated rail j oint unobstructed .

This obj ect is also achieved by an insulated rail j oint according to claim 13 . Therefore , the subj ect matter of the invention is an insulated rail j oint that is designed to accommodate the system or components of the system according to the invention .

This obj ect is also achieved by a rail according to claim 14 . Therefore , the obj ect of the invention is a rail that is designed to accommodate the system or components of the system according to the invention .

The measures according to the invention provide the advantage that the insulated rail j oint can be checked during normal rail operations and that damage can be detected in an early stage of degradation .

No labor intense measuring operations directly at the insulated rail j oint are necessary, which would hinder the normal rail operation . No special purpose measuring trains are required, which must be equipped with expensive measurement equipment , and which would occupy the track during measuring operations .

Once positioned, the system operates without any further human intervention, unless a service is necessary .

Here , "designed for stationary operation at the permanent way, preferably at the track" means that the technical design of the system is such that , once it is installed at the place where its operation is intended or where its operation takes place , it can remain at this location even during normal rail operations and it can carry out the monitoring of at least one state of the insulated rail j oint , even during regular rail operations .

Further to this , the regular rail operations is in no way hindered because the system according to the invention is designed to let trains pass over the insulated rail j oint with full regular traveling speed . Here , "designed such that a train can pass the insulated rail j oint unobstructed" means that the system leaves enough space for the train wheels and other equipment of the train to pass unobstructed during regular rail operation . Therefore , the system is placed and / or geometrically formed in such a way that it cannot collide with the dynamic envelope curve of a train that is traveling under the most unfavorable conditions along the track . In other words , the system is placed for stationary operation under consideration of the structure gauge , also called the minimum clearance outline and the system is placed and / or geometrically formed accordingly to the structure gauge . In summary, it can be said that the construction, shape and / or placement of the system is such that it maintains a di stance from the clearance profile .

Further particularly advantageous embodiments and extensions of the invention arise from the dependent claims and the following description .

In general , the track comprises the rails . Typically, the track also comprises a rail fastening system and railroad ties , that are also called sleepers , and ballast or a solid structure ( e . g . made out of concrete or asphalt ) . A track without ballast is known as a ballastless track or a slab track .

The term "track" in this context can be interpreted as the German term "Oberbau" or "Gleiskdrper" .

The permanent way comprises the track as well as the lineside structures such as retaining walls , fences along the rail corridor and so on .

The system may be designed for the stationary operation directly at the permanent way outside of the track . For this purpose the system might for example comprise a camera, that captures the insulated rail j oint .

However, it is of advantage , that the system is designed for the stationary operation directly at the track . This measure allows to acquire physical parameters representing the state of the insulated rail j oint at close range . Furthermore , this measure enables the system to be accommodated in a compact manner . The system can therefore easily be installed along the track without adversely af fecting other systems in the rail network .

The insulated rail j oint to which the system is used comprises the following elements :

- The insulating shim, which is intended to galvanically insulates two separate rail sections and is therefore installed between the two rail sections and rests against the end faces of the rail ends of the two rail sections , which means the end heads of two rails . The insulating shim is also referred to in the literature as the " insulating end post" .

- Two fishplates , which are attached to each side of the webs of two rails , which shall be j oint together by the fishplates . I f readily installed, the fishplates overlap the gap between the two rails connected together, wherein the insulating shim is installed in the gap between the two rails . Each fishplate shows drilling holes for the attachment to the web . The web of the rail is the part of the rail between the head of the rail , which is intended to carry the wheel of a train, and the foot of the rail , which is intended to be af fixed to the railroad ties , ( or sleepers ) , that are placed in the ballast . The fishplates overlap the insulating shim along the web of the rail and extend along a fraction of the length of the respective rail where they are attached . The fishplate is also referred to in the literature as the " j oint bar" .

- Two insulating layers , which are located between the fishplates and the rails and covers the entire surface where each fishplate and the rail s work together . The insulating layers are also known or referred to in the literature as a flexible ( sheet like ) insulating material . However, the insulating layer may comprise an, in particular flexible , insulating sheet . Preferably the insulating sheet is glued by a layer of glue onto the rails , which are connected by the insulated rail j oint . Preferably, the entire insulating layer may be reali zed by a layer of insulating glue that hardens .

- Insulation rolls , which form the innermost surface of the drilling holes through the web of the rail and are intended to provide a galvanic insulation there . The inner diameter of the insulation rolls is set to host bolts . The insulation roll is also referred to in the literature as the " insulating ferrule/ insulating sleeves" .

- A number of the bolts and nuts ( and washers ) , wherein the number corresponds to the number of drilling holes , which exist in the web of the two rails that shall be connected together . The bolts are intended to be placed in the drilling holes from one side of the web of the rails and the nuts are intended to be screwed onto the thread of the respective bolt from the other side of the web of the rails in order to fix a pair of fishplates onto the respective web of the rails to connect these two rails together . Washers may also be used at each bolt .

It is beneficial that at least a part of the system, preferably the entire system, is designed for the stationary installation on the insulated rail j oint or stationary installation in the vicinity of the insulated rail j oint or for the stationary integration into the insulated rail j oint or for the stationary integration in the vicinity of the insulated rail j oint .

In this context , " in the vicinity of the insulated rail j oint" means essentially along the rail or under the rail in the surrounding of the insulated rail j oint .

A system that is designed to be at least partially, preferably entirely, installed on the insulated rail joint or in the vicinity of the insulated rail joint can be realized by the aid of an adhesive connections or glued joints, screw connections, rivet connections, etc. These means allow the installation or affixing of the system on the insulated rail joint or in the vicinity of the insulated rail joint. For example, this measure allows the system to be easily retrofitted on the insulated rail joint.

A system that is designed to be at least partially, preferably entirely, integrated into the insulated rail joint or in the vicinity of the insulated rail joint can be realized by the aid of grooves or recesses in the insulated rail joint or the vicinity of the insulated rail joint. These recesses or grooves can, for example, be incorporated in the fishplate of the insulated rail joint or in at least one of the rails that are connected by the insulated rail joint. These means allow the system to be placed into the recesses or grooves at the locations where these grooves or recesses are realized. This measure allows the insulated rail joint and / or the rails to be checked directly at those points where damage or wear typically occurs.

It has been found to be advantageous that the system is designed to autonomously monitor the state of the insulated rail joint.

This means that the system monitors the state of the insulated rail joint without human intervention, so to say fully automatic.

Therefore, the system is preferably designed to independently determine when the states of the insulated rail joint is to be automatically monitored. Such an autonomous and automatic monitoring can be started, for example, when a certain time period has passed since the last monitoring. It is also possible that the system is designed to start or stop a monitoring as a function of previously acquired data and / or received data . The acquisition and receipt of this data is dealt with at a later point in the general description .

In addition to the fully automatic and autonomous functionality, the monitoring process can of course also be triggered manually, which can be triggered, for example , by workers on site or by an operator in a remote control-center .

To enable an automatic and autonomous monitoring of the state of the insulated rail j oint the system comprises a reliable autonomous power supply or is connected to an external power supply . The autonomous power supply may be reali zed by an energy storage like a long live battery or a rechargeable long live battery . Also , a solar panel , which may be placed at safe distance from the rails , and a rechargeable battery that is connected to the solar panel by wires and that harvests the power supplied by the solar panel may be used . Also , other measures for energy harvesting may be used . In the course of energy harvesting, the energy from the movements or vibrations of the rails as a result of trains passing over them can be converted into electrical energy, for example using piezoelectric crystals or magnets and coils . The system is therefore preferably designed to harvest the kinetic energy of the rails and convert it into electric energy . In the context of energy harvesting it has been of particular advantage that the system harvest energy by utili zation of the electric current that flow in the rails .

It is advantageous that an energy harvesting module is provided that simultaneously takes on the task of an acquisition stage or is part of an acquisition stage or is designed as an acquisition unit .

The system is therefore preferably also designed to be weather-resistant . This means that the components of the system as well as the mechanical af fixing to the permanent way, preferably the af fixing to the track, particularly preferably the af fixing or attachment to the insulated rail j oint or the vicinity of the insulated rail j oint , are designed to withstand the ef fects of humidity or water, temperature or temperature changes caused by environmental conditions and mechanical stress . An example of the loads that such a system can be exposed to can be demonstrated by a railway snowplow ( also known as wedge plow or Bucker plow) that pushes snow away from the rails . In this example , the system and the af fixing must withstand the mechanical loads caused by the moving snow or ice .

According to a further aspect of the invention the system is designed to monitor the state of an insulated rail j oint by the aid of an acquisition of at least one of the following physical parameters : a resistance , a vibration, a sound, a deformation and / or stress , a distance , an inductance , a capacitance , a temperature or a humidity or any similar parameter .

These physical parameters ( alone or in combination) provide a meaningful and convincing statement about the state of the insulated rail j oint or provide the basis for assessing or estimating this state .

In general , these measures can not only contribute to error or damage prevention but also to error diagnosis . This means that damage can not only be repaired before it disrupts rail operations , but the error or damage can also be found more quickly . These measures can also be used for the forecast of errors to be expected and the temporal behavior of the development of the state of the insulated rail j oint . In a resistance acquisition, at least the resistance of the insulating shim is preferably acquired here . A technically easy to implement and meaningful resistance acquisition is given i f the resistance of the insulating shim is recorded in series with sections of the two adj acent rails . A contactbased method as well as a contact- free (non-invasive ) method of detecting the resistance can be used here .

In the case of the vibration acquisition, it is advantageous that the system is designed to acquire (vertical and / or hori zontal ) vibrations of the rail or of the two rails that are connected by the insulated rail j oint . The acquisition can take place on or in one rail or on or in both rails or on or in the insulated rail j oint at one or more points /positions .

The acquisition of the sound can be done in the same places as the vibration acquisition . In contrast to the aforementioned vibration acquisition, the focus of the sound acquisition is on lower amplitudes and preferably higher frequencies . The sound acquired in this way can be used, for example , to draw conclusions about damage to the material of the insulated rail j oint or the rails connected by the insulated rail j oint .

According to one aspect of the invention, the system is designed to emit sound, preferably ultrasonic sounds . These emitted sounds can be acquired in the course of the sound acquisition, so that a comparison of the recorded sound with reference data is possible . This enables the early detection of small defects in the material of the insulated rail j oint and / or the rails .

The deformation and / or stress is acquired on the rails or the insulated rail j oint . The deformation and / or stress is preferably detected at a point where the insulated rail j oint and / or the rail are exposed to high mechanical loads . So it is advantageous to acquire the deformation and / or stress

- on the bolts or nuts of the insulated rail j oint or

- at the associated drilling holes ( or bore holes ) in the rail or the drilling holes in the fishplate of the insulated rail j oint ,

- on the insulating shim or

- between insulating shim and rail or on the front side of the rail or

- between the fishplate and the rail or

- on the rail in the area of the connection between the fishplate and the rail or

- on the fishplate in the area of the connection between the fishplate and the rail . The stress can be acquired indirectly via the acquisition of the deformation or the acquisition of a force , wherein the force is also detected indirectly by means of known measures .

The distance detection or distance acquisition can also be carried out at di f ferent points or positions . It has proven to be particularly advantageous i f the system is designed to acquire the distance to a predefined point or the change of distance of the rails in the longitudinal direction in the vicinity of the insulated rail j oint , preferably in the vicinity of the insulating shim . This measure allows an early detection i f the rail moves away from the insulating shim . This can take place , for example , in the event of extreme temperature fluctuations and / or loads from the trains in the longitudinal direction of the rails . The distance measurement makes it possible to determine this type of damage before the functionality of the insulated rail j oint is restricted .

The induction acquisition can also be carried out at di f ferent positions . It is advantageous i f the inductance is acquired in the vicinity of the galvanic separation of the insulated rail j oint , i . e . where changes in the state of the insulated rail j oint can be determined inductively . In this context , the change in inductance or the influence of magnetism can be used .

The capacitance acquisition can also be carried out at di f ferent positions . It has been found to be particularly advantageous here if the capacitance of two galvanically isolated points is checked for example, between the two rail sections that are galvanically separated and mechanically connected by the insulated rail joint, or between the fishplate of the insulated rail joint and one of the rails that are connected by the insulated rail joint.

The temperature and humidity can be acquired at different points. These point (s) may be located under the insulated rail joint or under the rail or on the underside of the insulated rail joint or the underside of the rail. The acquisition of temperature and/or humidity may also comprise or involve the temperature and / or humidity of the environment in the vicinity of the insulated rail joint.

In general, several of these physical parameters can be acquired. The system can also be designed to acquire one of the physical parameters at several positions. In some applications it is advantageous if, for example, the humidity and / or the temperature is acquired at several positions, for example in order to crosscheck measurements at different positions.

According to a further aspect, the system is designed to release an alarm signal and/or alarm data if the current state of the insulated rail joint deviates from a specified condition.

The specific condition may be pre-programmed state of the insulated rail joint, which is used to decide if an alarm shall be triggered or not. It acts as or is used as a reference "value" or "threshold". It may be determined by a single physical parameter selected from the parameters as explained before. However, it may also be determined by a physical parameter collection, for example the resistance and the vibration and the sound, wherein the different physical parameters may be weighted. Further to this, the specified condition may be a fixed value (determined by the respective physical parameter considered) or a value range . However, the speci fied condition may also be variable state of the insulated rail j oint because it may vary dependent on for example the temperature or the humidity in the vicinity of the insulated rail j oint . In this example a temperature and / or humidity dependent threshold is autonomously defined by the system itsel f . In general , the system may define a variable threshold based on available physical parameter ( s ) or other information received by a communication .

In the system the speci fied condition is used to be compared with the detected or determined ( current ) state of the insulated rail j oint . Depending on the respective physical parameter or combination of parameters the current state is autonomously determined by the system . As soon as the current state deviates from the speci fied condition the system triggers an alarm, which is communicated by means of a signal or data to a signal box .

This alarm can be used to validate the findings in the signal box . This measure therefore provides further redundancy and thus further security for checking the rail network .

Further to this , it is of advantage that the system is not only designed to submit signals or data but also to receive signals and / or data .

In particular it has been found to be advantageous that the system is designed to receive consideration data and the system is designed for the monitoring of the state of the train insulated j oint under consideration of the consideration data .

The consideration data can for example comprise environmental data or usage data .

Environmental data may include for example weather data which represent the present and / or future weather situation . Usage data may include information about the next train ( s ) that will pass the insulated rail j oint . Those information about the next trains may include information like a timetable , the type of train, load (weight/mass ) of a train or the wagons of the train ( s ) .

The consideration data enable the system to determine whether the currently monitored state of the insulated rail j oint can be valid under the current situation to be considered .

For example , with very heavy trains or when it rains , temporary states of the insulated rail j oint can occur that are otherwise not to be expected . Therefore , the consideration data enables the system to determine whether there is damage to the insulated rail j oint or whether temporary external conditions are influencing the insulated rail j oint in such a way so that is temporally seems to be damaged or degraded .

The consideration data can also be used to monitor the insulated rail j oint under defined conditions . In this way, the state can be checked when a known train with a known length and an essentially known weight travels over the insulated rail j oint . This observed state can be compared with an expected state , which would typically be expected under the considered situation that is defined by the consideration data or its interpretation, whereby a monitoring of the state of the insulated rail j oint under dynamic ( so to say temporal ) conditions is possible .

The system can be designed in di f ferent ways and comprise software and hardware in order to provide the functions described . In general , the hardware of the system can be implemented in di f ferent ways . The individual system components can be positioned in a distributed manner on the permanent way, preferably on the track . The hardware components or parts of the hardware components can also be accommodated together in one housing . In order to obtain a very compact and easily installable system, the hardware , in particular the electronics , of the system can be implemented as a multi-chip module or system-in-package . In order to obtain an even more compact system, the hardware of the system or part of the hardware of the system can be implemented as a system-on-a-chip .

In all of these embodiments , it has proven to be advantageous that the system comprises

- at least one acquisition stage which is designed to capture a physical parameter to characteri ze the state of the insulated rail j oint ,

- a processing stage which is designed to process the captured physical parameter and to generate delivery data which represents the state of the insulated rail oint ,

- a communication stage which is designed to deliver the delivery data .

The acquisition stage comprises electronics that processes analog or digital signals which are used in the acquisition process . The acquisition stage is typically reali zed by one acquisition unit . However, the acquisition stage may also comprise more than one acquisition units . The purpose of these acquisition units is to split the functionality of the acquisition stage ( for example to have a first transducer to emit a signal and a second transducer to receive a signal ) or to allow the installation of identical functionalities at di f ferent positions or positions , respectively . The acquisition unit provides the physical interface to the insulated rail j oint or the rails which are connected together by the insulated rail j oint or the railroad ties ( or sleepers ) that carry the rails or the ballast that carries the railroad ties ( or sleepers ) for the acquisition process . The acquisition stage delivers digitally processable acquisition data, which represent the captured physical parameter, to the processing stage where the captured physical parameter is processed to derive and monitor the state of the insulated rail j oint , which is represented by the delivery data which may be submitted by the communication stage , i f necessary, for example when the alarm is triggered, or demanded, for example when the state of the insulated rail j oint is checked by another device of the railway company that operates and maintains the rail network .

The communication stage may be designed for wirebased communication . Preferably the communication stage is designed for radio-based communication, which emphasi zes the general concept of a system that autonomously monitors the insulated rail j oint at remote locations along a rail track where any cabling or wires should be avoided for the sake of simplicity of installation and for the sake of safe operation . Communication cables and the like along a railway line would typically be di f ficult to maintain, which is what the invention is intended to avoid . Therefore , for example , the communication stage is designed to communicate according to conventional modern cellular communication standards like 4G or 5G or higher . 4G stands for the fourth generation technology standard for broadband cellular networks and 5G stands for the fi fth generation technology standard for broadband cellular networks . It may also be designed to communicate according to a proprietary communication protocol in order to be independent from general purpose communication load on such standardi zed 4G or 5G communication networks . Also technology according to the railway speci fic communication standard like GSM-R or the newer FRMCS ( Future Railway Mobile Communication System) may be used . Further to this , also NB- IoT (narrow band internet of things ) or NFC communication technology may be used to enable , for example , a radio communication with the communication stage in its proximity or with devices di f ferent from cellular based radio communication devices .

When the acquisition stage captures the physical parameter, it can be a process , in particular a measurement , in which a quantitative value representing this physical parameter is determined . However, the capturing of the physical parameter can also involve the determination of a qualitative value , for example a comparison in which it is checked whether certain condition has already been met or whether certain conditions have already been met , for example whether a certain temperature has been exceeded, as is the case with temperature switches , for example .

In the following, some examples of acquisition units are provided .

In order to carry out a resistance acquisition, the acquisition stage can be reali zed as a resistance measuring device . Here , two acquisition units can be provided, which are connected to the insulated rail j oint or the rails at two di f ferent points that should be galvanically separated from one another by the insulating elements of the insulated rail j oint . A predefined voltage can now be applied between the two contact points and the current flowing between the acquisition units can be measured or checked . The resistance can now be determined from the measured current at the pre-defined voltage .

In order to carry out a vibration acquisition, at least one acceleration sensor can be provided as an acquisition unit . Such an acceleration sensor can be designed as a micro electromechanical system (MEMS ) or mechanical sensor system . The acceleration sensor is preferably in contact with the insulated rail j oint or the rails but may also be in contact with one of the railroad ties ( or sleepers ) beneath the insulated rail j oint . The acquisition unit for performing the vibration acquisition is preferably located on the insulated rail j oint or at a point that is vibrationally connected to the insulated rail j oint , particularly preferably on the insulated rail j oint or the rails . Likewise , the sensor can also be accommodated in the housing of the detection stage ( or the electronics ) because this housing is itsel f set in motion by its structural coupling with the oscillating components .

In order to carry out a sound acquisition, the acquisition stage can comprise a microphone as an acquisition unit . According to a preferred embodiment , the microphone is designed as a structure-borne sound microphone . A piezoelectric pickup can be provided for this purpose , for example . The microphone may also have directional characteristic ( directivity) which is oriented in direction of or in direction towards the rails or the insulated rail j oint to capture sound generated there .

According to a further embodiment , a loudspeaker, in particular a piezo loudspeaker, is provided as a further acquisition unit , which is designed to send an acoustic signal , in particular an acoustic pulse , into an obj ect of the permanent way, preferably into an obj ect of the track, in particular the insulated rail j oint and / or at least one of the rails connected by the insulated rail j oint .

A first acquisition unit can thus be designed to send out the acoustic signal so that the acoustic signal reaches the second acquisition unit via the obj ect to be checked, in particular via the insulated rail j oint or parts of the insulated rail j oint and / or at least one of the rails connected by the insulated rail j oint , such that the second acquisition unit can detect this signal . The second acquisition unit can receive the signal and transmit the detected signal or its signal parameter to the processing stage . The processing stage is designed to interpret the detected signal or its parameter based on the signal sent out by the first acquisition unit .

In order to carry out a sound acquisition the acquisition stage can comprise an ultrasonic testing unit , which is designed to perform an ultrasonic testing . The acquisition stage might comprise locally distributed ultrasonic testing units to perform the ultrasonic testing .

In order to carry out a sound acquisition the acquisition stage can comprise an acoustic emission sensor that is designed to sense sound in the material of the insulated rail j oint or one of the rails as a result of loading and / or damages in the material .

Deformations and thus stresses can be acquired using strain gauges which are in contact with the rails or the insulated rail j oint .

A distance acquisition, as well as a vibration acquisition, can take place , for example , by means of a laser or by means of a camera , preferable in connection with reference marks or the like , and corresponding evaluation software , such as modern computer vison . The distance can also be acquired using a rod which, for example , establishes an electric contact or opens and electric contact as soon as a certain distance is exceeded .

Inductive acquisition or measurements for testing rails are for example known as eddy-current testing . The acquisition unit ( s ) can therefore be designed to perform an eddy-current test .

To carry out a capacitive acquisition or measurement , a first acquisition unit is attached to a first ( contact ) point on the rail or the insulated rail j oint and a second acquisition unit is attached to a second ( contact ) point that should be galvanically separated from the first point of the rail or the insulated rail j oint . The insulating elements , i . e . the insulating layer and / or the insulating shim and / or the insulation rolls , act as the dielectric of a capacitor . Based on the charging and discharging profile of this capacitor, which is typically caused by an alternating signal applied between the two contact points , conclusions can be drawn about the state of the dielectric, i . e . about the state of the insulating elements ( the insulating layer and / or the insulating shim and / or the insulation rolls ) . The question which insulating elements are involved in this acquisition process depends on the positioning of the first and the second acquisition unit .

According to one aspect of the invention the insulated rail j oint comprises an insulating shim that galvanically separates two rail sections and wherein the acquisition stage is designed to capture the physical parameter at at least two di f ferent capture positions , relative to the insulating shim, preferably wherein the two capture positions are located on di f ferent sides of the permanent way, particular preferably wherein the two capture positions are located on di f ferent sides of the track, divided by the insulating shim .

This measure is very advantageous because the insulating shim usually represents the part of the insulated rail j oint that is most frequently involved in damage . This measure makes it possible to monitor precisely this weakest part or a point with a defined position in relation to this weakest point of the insulated rail j oint and the connected rails .

With the phrase "the two capture positions located on di f ferent sides of the permanent way divided by the insulating shim" is meant , that the insulating shim separates the permanent way in longitudinal direction parallel to the rails . Along this longitudinal direction the two rails and the insulated rail j oint extend, wherein the two rails are separate by the insulating shim into two areas , wherein each area is comprising at least one rail and a part of the insulated rail j oint . The same applies in an equivalent manner to the phrase "the two capture positions located on di f ferent sides of the track divided by the insulating shim"

In other words , this means that the acquisition stage comprises a first acquisition unit that is designed to be placed at the first rail section or corresponding to the first rail section on the permanent way, preferably on the track, preferably corresponding to the first rail section on the insulated rail j oint , and a second acquisition unit and the second acquisition unit is designed to be placed at a second rail section or corresponding to the second rail section on the permanent way, preferably on the track, preferably corresponding to the second rail section on the insulated rail j oint .

In general , the acquisition units that are located at di f ferent places can be connected with the other acquisition units and / or the processing stage via wire or via radio signal and the like .

According to one aspect of the invention, it is advantageous that the acquisition stage is designed to be placed at least partially directly at or in one of the rail sections that are connected by the insulated rail j oint . This positioning allows a precise determination of the state of the insulated rail j oint . On the one hand, physical parameters such as the electrical resistance or the capacitance of the insulated rail j oint can be detected or acquired . On the other hand, the physical parameters that act on the insulated rail j oint via the rails , such as movement or expansion or tension, can be detected or acquired .

Preferably the acquisition stage comprises at least one acquisition unit that is designed to be placed directly at or in one of the rail sections . The acquisition unit is particularly preferably placed within a reserved space or length around the connection point of the two rails , which is the location of the insulating shim . For example , in case of Austrian railway systems such a reserved space extends over 60 cm . This has the advantage that the system components can be placed on the rail without hindering other devices that are required for rail operations .

According to another aspect of the invention, it is advantageous that the insulated rail j oint comprises at least one fishplate . Such a fishplate may carry the entire system, many parts of the system or only selected components or even only one component of the system . However, the entire system, many parts of the system or only selected components or even only one component of the system may be located in the fishplate . However, in a preferred embodiment , at least a part of the acquisition stage , preferably the entire acquisition stage , is designed to be placed on or in the fishplate .

All these measures enable the system to be integrated directly during manufacture or installation of the insulated rail j oint . It therefore allows a compact embodiment of the system and a delivery of fishplate with all acquisition equipment carried by it . In the case of the design that parts of the system, in particular the acquisition stage , is/are to be integrated in the fishplate , the fishplate naturally also has a corresponding design, for example a space for integration to accommodate the acquisition stage .

According to another aspect of the invention, it is advantageous that the system comprises at least one mounting plate on or in which the acquisition stage and / or at least one acquisition unit of the acquisition stage is / are placed, wherein the mounting plate is designed to be attached to the fishplate of the insulated rail j oint or at least one of the rails connected by the insulated rail j oint . This measure enables the system to be easily retrofitted to existing insulated rail j oints .

Preferably the mounting plate is designed in a way that all components of the system can be accommodated on the mounting plate .

One or several mounting plates can be provided . For example , one single mounting plate can be provided that is designed to be mounted on the fishplate . According to another exemplary embodiment , one mounting plate can be provided on the left and one mounting plate on the right side of the fishplate . The separate mounting plates can be attached to the left and right ends or the fishplate . The separate mounting plates can also be attached in the proximity of the left and right ends or the fishplate directly to the rails which are connected together by the fishplate .

In this configuration the system may be split in two system modules , each being carried by the respective mounting plate . The two system modules may be connected by a system bus to allow an electrical power transmission between the two system modules or the exchange of data or information . Each of the two system modules may carry out di f ferent acquisition process and is therefore embodied with di f ferent acquisition units .

However, according to a further embodiment the two system modules may also be of identical embodiment . This allows a crosscheck of the results of one of the modules by the results of the other module . This crosscheck may not only be performed at a remote location where the data or information delivered by the identical modules are processed . In particular the crosscheck is performed directly by the modules which exchange their acquisition data or their monitoring results . It also allows the creation of redundancy so that one of the modules can take over the delivery of data even i f the other module is out of operation, deinstalled or in a service mode .

According to another exemplary embodiment two mounting plates are placed next to both fishplates of the insulated rail j oint , so that a total of four mounting plates are provided for one insulated j oint . Here again the options and advantages as discussed in the preceding paragraph do apply .

I f synergies of the hardware are demanded, some of the components of the system, in particular the processing stage and the communication stage can be provided only at one of the systems modules per insulated rail j oint . In this configuration only the acquisition stages are distributed over the number of system modules , while processing of the acquisition data of the di f ferent acquisition stages is performed by only one central processing stage .

According to another aspect of the invention, it is advantageous that the acquisition stage , preferably a part of the acquisition stage , more preferably an acquisition unit of the acquisition stage , is designed to be placed on a web of a rail . This enables the acquisition stage or the acquisition unit to be positioned in a stable manner without hindering rail operations . This measure makes sure that the part of the rail that is occupied by the train wheel and that part of the rail that is used to af fix the rail to the railroad tie ( or sleeper ) is free from any system components . Therefore , the rail can be used unobstructed by trains and workers dealing with the attachment of the rail onto the railroad tie ( or sleeper ) are not hindered by the installation of the system . In particular the width, height and length are set such that it leads to relatively slim device , which can be attached to the web of the rail . In summary, it is of advantage that the insulated rail j oint comprises a mounting plate , wherein the mounting plate is designed in such a way that the system or components of the system can be attached to the insulated rail j oint relatively easy .

Such a mounting plate can be implemented, for example , by means of threads , bores , recesses , and grooves . The acquisition units can be placed in recesses , for example , in order to record the physical parameters such as resistance or vibrations on the rails in the direct vicinity of the insulating shim .

The mounting plate is preferably designed to permanently connect the system to the insulated rail j oint .

The mounting plate is particularly preferably implemented at least in places by means of a welded connection .

The insulated rail j oint is preferably designed to accommodate the system on or in at least one of the fishplates .

The rail can also comprise a mounting plate , wherein the mounting plate is designed in such a way that the system or components of the system according to the invention can be attached to the rail .

As mentioned in the context of the insulated rail j oint , such a mounting plate can be implemented, for example , by means of threads , bores , recesses , and grooves . The acquisition units can be placed in recesses or holes in the rail , for example , in order to record the physical parameters such as resistance or vibrations on the rails in the vicinity of the insulating shim .

The mounting plate is preferably designed to permanently connect the system to the rail .

The mounting plate is particularly preferably implemented at least in places by means of a welded connection . Finally, it is emphasi zed that electronic devices mentioned may be reali zed by the aid of well-known discreet and/or integrated electronics . In case of interfaces required, the person skilled in the art will be able to select and design the appropriate interfacecircuitry ( transceivers ) to enable data and/or signal communication . Programmable devices may comprise a microprocessor and some peripheral electronics . Such programmable devices may also be reali zed by the aid of a microcontroller or an application speci fic intergraded circuit (AS IC ) and the like . Execution of software routines on such programmable devices provides computer implemented functions that are discussed herein .

According to one aspect of the invention, the system can operate in two di f ferent modes , namely in a sleeping mode and in an active mode . In the sleeping mode several components of the system, especially some or all acquisition units may be deactivated . Only the remote communication functions may still be active . In the active mode all components are active so that the system can monitor the state of the insulated rail j oint . The system switch between the two modes autonomously, for example periodically or according to a timing provided by the consideration data or in dependency on remote commands received by the remote communication function . However, the system can also be implemented in such a way that all components are inactive in the sleeping mode and are only activated when an external influence on the sensor used exceeds a threshold value .

These and other aspects of the invention are obtained from the figures discussed below .

BRIEF DESCRIPTION OF THE FIGURES The invention is explained again hereafter with reference to the attached figure and based on exemplary embodiments , which nevertheless do not limit the scope of the invention. The Figure shows in schematic fashion in :

Fig . 1 a permanent way and a signal box,

Fig. 2A, 2B an insulated rail joint and its vicinity in two different perspectives,

Fig. 3A-3C the insulated rail joint and details of its connection with two rails,

Fig. 3D a fishplate of the insulated rail joint,

Fig. 3E an exemplary clear track circuit using the insulated rail joint,

Fig. 4A, 4B a first exemplary embodiment of a system for monitoring the state of the insulated rail joint.

Fig . 5 a second exemplary embodiment of the system,

Fig . 6 a third exemplary embodiment of the system,

Fig . 7 a demonstration of the system in action.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Fig. 1 visualizes a permanent way 211 symbolized by a dashed square, that comprises a track 210, symbolized by a dashed two-dotted square, and exemplarily two fences 212 and an overhead line mast 213. In general, the permanent way 221 refers to the track 210 in addition to lineside structures. Those structures can differ from the exemplarily embodiment mentioned, namely the fences 212 and the overhead line mast 213.

The track 210 comprises rails 201a - 201f (see also the following figures) and in this exemplary embodiment railroad ties 202 that are laid upon track ballast 204. In addition to the exemplary embodiment shown here , there are ballastless tracks ( also known as slab tracks ) . In the case of ballastless tracks , the ballast 204 and the railroad ties 202 are replaced by a solid structure made of concrete or asphalt . In this case the track 210 comprises the rails 201a and 201c and the solid structure .

In Fig . 1 , the outline of a signal box 209 is indicated . The signal box 209 is only shown symbolically here and can be located anywhere along the permanent way 211 , or even apart from the permanent way 211 . The signal box 209 comprises a so-termed interlocking, which is an arrangement of signal apparatus that prevents conflicting movements of trains through an arrangement of tracks such as j unctions or crossings . For this purpose , the signal box 209 comprises a central computer that is designed to evaluate incoming data and signal s received from devices that are installed along the track 210 . The signaling box 209 shown here symbolically is usually designed as a control center in practice , which monitors and controls a large part of the rail network .

Fig . 2A and 2B visuali ze an insulated rail j oint 101 and its vicinity that is indicated by a dot-dashed square 100 , herein referred to as vicinity-area 100 . The insulated j oint 101 is located in the center of the vicinity-area 100 . As shown in Fig . 2A the insulated rail j oint 101 connects the first rail 201a and the second rail 201b . The rails 201a and 201b are fixed to the railroad ties 202 by means of rail fastening systems 203 .

Representing all rails 201a - 201 f , the cross section of the second rail 201b is indicated on the right edge of the Fig . 2A. The rail 201b consists of a head 207 on which the wheels of trains passing over can roll , a foot 205 that stands on the railroad ties 202 and a web 206 that connects the head 207 and the foot 205.

The structure of the insulated rail joint 101 is visualized in Figures 3A to 3D.

Fig. 3A visualizes a side view of the insulated rail joint 101 and the two rails 201a and 201b, which are connected by the insulated rail joint 101.

Fig. 3B visualizes a cross section through the web 206 of the rails 201a and 201b and the insulated rail joint 101, visualized in Fig. 3A.

Fig. 3C visualized a cross section normal to the longitudinal direction of the rails 201a and 201b.

As shown in the Fig.3A to 3C, (especially in Fig. 3C) , the insulated rail joint 101 comprises two fishplates 102 that hold the rails 201a and 201b together by means of bolts 105 (and washers) and nuts 106. The insulated rail joint 101 comprises two insulating layers 104 that are located between each fishplate 102 and sections of the rails 201a and 201b that are connected by the aid of the fishplate 102. The insulating layer 104 separates each fishplate 102 galvanically from the rails 201a and 201b.

As shown in Figs. 3C and 3D, the shape of the fishplate 102 follows the shape of the rails 201a and 201b, so that a stable connection between the rails 201a and 201b and the insulated rail joint 101 is provided .

As shown in the Fig.3A to 3C, (especially in Fig. 3A and 3B) , the insulated rail joint 101 comprises one insulation roll 107 for each bolt 105. The insulation rolls 107 are located in drilling holes in the web 106 of the rail 201a and 202b and each bolt 105 is located in the corresponding insulation roll 107 so that the insulation rolls 207 separate the bolts 105 galvanically from the rails 201a and 201b.

As shown in the Fig. 3A and 3B, the insulated rail joint 101 comprises an insulating shim 103 which is located between abutment surfaces of the two connected rails 201a and 201b wherein the insulating shim 103 separates the two rails 201a and 201b galvanically .

Fig . 3E visuali zes the use of the insulated rail j oints 101 in a railway signaling system for the detection of track section ( or track block) occupation by trains . In particular, the Fig . 3E shows a simple "clear track circuit" . For the purpose of visuali zation only, the insulating shims 103 are shown much thicker than they actually are . One side of the track 210 is assembled by the sequence of the rails 201 f , 201c, and 201d . In parallel thereto the other side of the track 210 is assembled by the sequence of the rails 201e , 201a, and 201b . In this simpli fied illustration each parallel pair of rails 201 f and 201e , 201c and 201a, 201d and 201b forms a track block, for which only the middle track block is shown with the clear track circuit connected to it .

In this clear track circuit the rail 201a and the rail 201c are connected to a DC power source reali zed by a battery 214 , wherein the rail 201c is connected to the positive terminal of the battery 214 and the rail 201a is connected to the negative terminal of the battery 214 . The rail s 201a and 201c are also connected to a relay 215 . The relay 215 is typically located in the signal box 209 . The relay 215 operates a switch 216 , which provides a signal in the signal box 209 . The switching state of the switch 216 ( switch does not mean railroad switch in this case ) determines a signal that indicates either that the track block is occupied by a train or that the track block is not occupied by a train . The signal may be visuali zed in di f ferent colors .

I f there is no train on the track block reali zed by the pair of rails 201a and 201c, the relay 215 is active (powered by the battery 214 ) and the switch 216 is in the appropriate position, which indicates that there is no train on this track block . I f a train now enters this track block, it short-circuits the rails 201a and 201c with its wheels and axel configuration . As a result , the relay 215 is no longer powered by the battery 214 and therefore is deactivated . This causes the switch 216 to toggle so that the signal indicates that a train is in this track block .

In addition to this exemplary embodiment shown here , there are other options for integrating the insulated rail j oints 101 into a rail network in order to determine the position of the trains with their help . For example , one side of the rail track can also be installed without insulated rail j oints 101 , while the other side of the rail track is subdivided with insulated rail j oints 101 in track blocks . Here , too , when the respective track block is occupied by a train the clear track circuit is influenced by the train as explained above so that the relay 215 is deactivated .

Fig . 4A visuali zes a system 1 for monitoring the state of an insulated rail j oint 101 .

In this exemplary embodiment the system 1 comprises a mounting plate 5 which carries or comprises , respectively, all the other ( in particular electronic ) components of the system 1 . In particular, these other components are embedded into the structure of the mounting plate 5 so that the mounting plate 5 provides a protection against environmental influences .

The mounting plate 5 is attached to the fishplate 102 of the insulated rail j oint 101 with the bolts 105 and nuts 106 of the insulated rail j oint 101 ( as shown in Fig 4B ) . Therefore , the mounting plate 5 comprises appropriately positioned drilling holes . The mounting plate 5 is designed to be correspondingly stable and resilient .

As shown in Fig 4A, the system 1 comprises a processing stage 3 , reali zed as a microcontroller, a communication stage 4 , reali zed as a radio module ( transceiver module ) , and an acquisition stage 2 , wherein the acquisition stage 2 is reali zed by several acquisition units 8 , 9 , 10 , 11 and 12 , wherein each of these acquisition units 8 - 12 acquires a physical parameter of interest to speci fy the condition of the insulated rail j oint 101 . All the acquisition unites 8 - 12 are connected to the processing stage 3 by individual cables or wires (not shown) or by a systembus (not shown) . The electrical interconnection between the processing stage 3 and the acquisition unites 8 - 12 may also make use of a so termed printed circuit board, which carries the conductor tracks . The arrangement of the processing stage 3 and the acquisition units 8 - 12 may be reali zed as a system on a chip (which is hosted in a casing) or preferably as a system-in-package .

One of the acquisition units 8 - 12 is reali zed as a temperature sensor 8 . The temperature sensor 8 is designed to transmit a temperature-sensor-signal (not shown) to the processing stage 3 , wherein the signal is influenced or defined by the temperature to which the temperature sensor 8 is exposed .

One of the acquisition units 8 - 12 is reali zed as a resistance acquisition unit 9 and designed to determine an electrical resistance between the two rails 201a and 201b , which are separated by the insulated rail j oint 101 . In this exemplary embodiment , appropriate drill ing holes have been made through the fishplate 102 and the insulating layer 104 in order to enable the respective rail 201a or 201b to be contacted by contact elements (not shown) of the resistance acquisition unit 9 . According to a further embodiment , the resistance acquisition unit 9 is attached in the lower area of the mounting plate 5 and in contact with the foot 205 of the respective rail 201a or 201b . In this exemplary embodiment , it is possible to detect the resistance without additional drilling holes in the insulated rail j oint 101 . In both cases , the resistance acquisition unit 9 is designed to transmit a resistance-acquisition-signal to the processing stage 3 . This signal is influenced or defined by the resistance between two rails 201a and 201b .

In the exemplary embodiment shown in Fig . 4A, one of the acquisition units 8 - 12 is reali zed as a vibration and shock sensor 10 . The vibration and shock sensor 10 is designed to sense accelerations of the mounting plate 5 , i . e . accelerations of the rails 201a and 201b to which the mounting plate 5 is attached, and to transmit a vibration and shock sensor signal to the processing stage 3 . This signal is influenced or defined by the vibration of the mounting plate 5 or the shock, which impacts the mounting plate 5 .

One of the acquisition units 8 - 12 is reali zed as a humidity sensor 11 . The humidity sensor 11 is used to sense the humidity on rails 201a and 201b, to which it is attached or of the vicinity of the insulated rail j oint 101 , so to say in the environment of the insulated rail j oint 101 . The humidity sensor 11 is designed to transmit a humidity sensor signal to the processing stage 3 . This signal is influenced or defined by the humidity to which the humidity sensor 11 is exposed .

One of the acquisition units 8 - 12 is reali zed as an acoustic emission sensor 12 . The acoustic emission sensor 12 is used to sense the sound transmitted from the solid material next to the sound sensor 12 and to transmit an acoustic emission sensor signal to the processing stage 3 . This signal is influenced or defined by the sound in the vicinity of the sound emission sensor 12 .

The processing stage 3 receives the di f ferent signals from the acquisition units 8 - 12 and converts these signals in digitally processable acquisition-data by its analog- to-digital conversion stage . It stores the acquisition-data, which represents the respective signal ( acquisition parameter ) received from the individual acquisition units 8 - 12 in a data structure . Then, it checks for each acquired parameter i f the respective value exceeds or falls below a threshold- value or threshold- value ranges . Dependent on the actual implementation, an alarm is triggered i f one or a plurality of these parameters exceeds such a threshold .

The communication stage 4 delivers an alarm signal and, i f implemented, also the acquisition data, which led to the alarm-signal to an external data processing device , which may be the mentioned central computer in the signal box 209 . The communication stage uses a 4G radio communication link for this purpose . Of course , the transmission can also be sent to any other device that is responsible for monitoring or taking actions .

According to a further embodiment of the invention the system 1 is designed to receive consideration data from an external source , which may be the central computer in the signal box 209 . These consideration data are received via the communication stage 4 and used by the processing stage 3 to adapt the respective threshold to circumstances represented by the consideration data . The consideration data may comprise environmental data or usage data .

The environmental data comprise data on the current weather situation and, i f available , seismic activities . The environmental data which describe the weather situation may have an impact on the threshold for the j udgment of the acquires humidity or the acquires resistance . Higher humidity may lead to a reduced resistance so that the threshold for the resistance must be lowered ( at least for the higher humidity period) in order to avoid a faulty alarm signal trigger . Similar to this , the environmental data which describe seismic activities may have an impact on the threshold for the j udgment of the acquired parameter that describes vibration and shock . More intense seismic activities may lead to an increase of the threshold value in order to avoid a faulty alarm trigger .

The usage data may contain data sets about the trains that are currently passing over the insulated rail j oint 101 or will soon pass over the insulated rail j oint 101 . The data sets may include the schedule , type ( and number ) of locomotive ( s ) of the train, the type and number of wagons of the train, the number and placement of the axes of the train, the weight and the weight distribute of the train, the speed of the train and so on . The usage data may directly determine the threshold to be set or temporal behavior of the threshold to be set ( during a period) in order to apply a realistic threshold for the usage of the train track .

As a consequence of the adaptation of the respective threshold the system 1 evaluates a current acquired physical parameter against the adapted respective threshold not only statically but also following the temporal behavior of the threshold .

In order to achieve this , the processing stage 3 is designed to process the signals received from the acquisition units 8 - 12 under consideration of the consideration data received from the communication stage 4 , which consideration data influence the threshold of the respective underlaying physical parameter .

According to an example , the processing stage 3 defines for each physical parameter that is represented by the acquisition-data a range , indicated by an upper and a lower threshold value , within which the respective physical parameter should lie i f there is no damage to the insulated rail j oint 101 or to the connection established by the insulated rail j oint 101 . This definition of the range may be based on initial definition data which were originally programmed into the system 1 or uploaded initially into the system 1 or modified from time to time in an automatic re-calibration process. This definition may also be based on a temporal development of the respective physical parameter which may be caused by slow degradation of the insulated rail joint 101 or other environmental influences. The originally set range of one of the physical parameters or its temporal development may also depend on the other acquired physical parameter ( s ) , which is taken into account by the software of the system 1, as explained in the context of a resistance that is dependent on the weather condition, in particular the humidity. This definition may also take the consideration data into account to consider external circumstances which influence the acceptable range of the respective threshold .

If one (or more) acquired signal (s) received from the acquisition units 8 - 12 is (are) in the accepted range, i.e. the acquired state of the insulated rail joint 101 is OK, no further steps need to be initiated. The communication stage 4 and the processing stage 3 may transmit a confirmation signal to the central computer at regular intervals (e.g. every 10 days) , if the acquired state of the insulated rail joint 101 is OK.

However, if one (or more) signal (s) is out of the accepted range, which give an indication of wear, serious degradation, or damage of the insulated rail joint 101, i.e. the acquired state of the insulated rail joint 101 is not OK, the processing stage 3 generates delivery data (which represent an alarm) and transmits the delivery data to the communication stage 4. The delivery data are received by the central computer and interpreted accordingly to automatically trigger further actions like a service request for the respective train track or even trigger a shutdown of the respective train track, i f the delivery data give rise to this . The delivery data may also include a message that informs an employee of the railway company, that the insulated rail j oint 101 needs to be checked and / or repaired, and / or a data set with data representing the detected signals . In particular the delivery data convey a unique identi fier to identi fy the insulated rail j oint 101 that is concerned .

Furthermore , the system 1 comprises two rechargeable batteries 6 and an energy harvesting module 7 that is designed to load the batteries 6 with electrical energy . In this exemplary embodiment the energy harvesting module 7 comprises a magnet and a coil to harvest energy from the acceleration (vibration) of the energy harvesting module 7 , when trains pass the insulated rail j oint 101 . But also energy harvesting directly from currents flowing in the rails may be implemented . According to another exemplary embodiment , a system without the energy harvesting module 7 may be used . In this case , the batteries 6 must be designed for the service li fe o f the insulated rail j oint 101 or to be regularly charged and / or replaced .

Fig . 4B visuali zes the cross-section of the rail 201a and the insulated rail j oint 101 with the attached system 1 . As shown here , in this exemplary embodiment , all components of the system 1 are integrated in the mounting plate 5 in such a way that the mounting plate 5 forms the outer boundaries of the system 1 . This makes the system 1 very compact , so it does not disrupt train traf fic, and at the same time is protected from environmental influences . In this configuration the system 1 may either be pre-installed on the fishplate 102 , preferably that fishplate 102 which is located on the outer side of the rails of the rail track, before it is installed on the rail track . However, the mounting plate 5 , which carries all the system 1 , can be retrofitted onto the rail track on an already installed insulated rail j oint 101 .

Fig . 5 visuali zes another exemplary embodiment of the system 1 , wherein the system 1 comprises two mounting plates 14 a and 14b or in other words a divided mounting plate 5 , which comprises two mounting plate modules 14a and 14b . The two mounting plates 14a and 14b are placed next to the fishplate 102 of the insulated rail j oint 101 in the longitudinal direction of the rails 201a and 201b . The system 1 in this exemplary embodiment also comprises the processing stage 3 , the communication stage 4 and the acquisition stage 2 wherein the acquisition stage is reali zed by several acquisition units 8 , 9 , 10 , 11 and 12 , as described in the context of Fig . 4A and 4B . The system in Fig . 5 also comprises two batteries 6 and an energy harvesting module 7 .

The system 1 in Fig . 5 comprises a connection unit 13 that connects the two mounting plates 14a and 14b, more precise the electrical components of the system 1 placed in the two mounting plates 14a and 14b . The connection unit 13 comprises a bus that provides the data and electrical power ( energy) transition between the components on the two connected mounting plates 14a, 14b . Furthermore , the connection unit 13 comprises a bus-cover, that covers the hardware of the bus and protects it from external influences such as mechanical load or moisture . The connection unit 13 is formed and / or located such that bolts 105 are freely accessible . In this exemplary embodiment , the mounting plates 14a and 14b are permanently glued onto the rails 201a and 201b .

Fig . 6 visuali zes another exemplary embodiment of the system 1 , wherein some components of the system 1 are placed directly on the insulated rail j oint 101 and other components of the system 1 are placed on the rails 201a and 201b in the vicinity-area 100 of the insulated rail j oint 101 . In this embodiment two vibration and shock sensors 10 and two sound emission sensors 12 are placed directly on the rails 201a and 201b . The resistance acquisition unit 9 is placed under the feet 205 of the rails 201a and 201b and the resistance acquisition unit 9 is connected with the two feet 205 of the rails 201a and 201b, so that the resistance acquisition unit 9 can detect the electrical resistance between the two rails 201a and 201b . The temperature sensor 8 and the humidity sensor 11 in this embodiment are also placed under the feet 205 of the rails 201a and 201b . The battery 6 and the energy harvesting module 7 , as well as the processing stage 3 and the communication stage 4 , are placed on the fishplate 102 of the insulated rail j oint 101 . The hardware components of this system 1 are connected with each other via the connection unit 13 , which in the present case may be reali zed by durable wires or also a solid connector module as described in the context of the Fig . 5 .

Fig . 7 visuali zes the system 1 in action . It shows a train 300 approaching the insulated rail j oint 101 . The insulated rail j oint 101 is equipped with the system 1 according to the Fig . 4A and 4B . Underneath one of the railroad ties 202 next to the insulated rail j oint 101 is a cavity 208 . The cavity 208 is caused by the fact that the track ballast 204 was displaced by past usage of the train track . While the train 300 is traveling over the rails , this cavity 208 causes increased stress on the insulated rail j oint 101 , which means that the state of the insulated j oint is not OK .

Here , the processing stage 3 has already received the consideration data via the communication stage 4 . In this example the consideration data include information about the weather, i . e . the expected humidity and the expected temperature , the information that no seismic activity was detected and a schedule about the next train, that will pass the insulated j oint as well as the data set that describes this train .

The system 1 can operate in two di f ferent modes which are distinct from each other by the power consumption of the system 1 . The first mode is an energy saving sleeping mode . In the sleeping mode the state of the insulated rail j oint 101 is not monitored . It is typically set when no train is passing . The second mode is an active mode , in which the system typically consumes more power than in the sleeping mode . In the active mode the system 1 monitors the insulated rail j oint 101 .

The change over from the sleeping mode into the active mode can be done automatically by the system 1 . The system 1 switches into the active mode in which the acquisitions are carried out , i f the energy harvesting module 7 now receives vibrations due to an approaching train 300 , or i f the processing stage 3 detects that it is time for a train to pass because the consideration data indicate this .

In this exemplary embodiment only one signal ( in particular its temporal behavior ) is discussed, which is the signal from the vibration and shock sensor 10 that is sent to the processing stage 3 .

After installing the system 1 , a nominal characteristic of the expected vibrations is recorded . This is done with a reference measurement , in which either a vibration pattern is determined while a train is passing by, or a vibration corresponding to the passing train is arti ficially caused by the on-site support staf f or a local vibratory device . Preferably also under the consideration of the consideration data received, the processing stage 3 creates a nominal characteristic curve 15 of vibrations to be expected over time when the train 300 passes the insulated rail j oint 101 . This nominal characteristic curve 15 is to be expected, i f the ballast 204 would be in place under all the railroad ties 202 by the given characteristics of the train 300 , which may be weight of the train 300 , weight distribution along the train 300 , length of the train 300 , speed of the train 300 and so on . The nominal characteristic curve 15 is shown schematically by the amplitude curve occurring during the vibration over time in the small diagram close to the system 1 .

Thereafter, in autonomous operation, during the acquisition process the acquisition unit 10 transmits its signals to the processing stage 3 and the processing stage 3 creates the actual acquisition curve 16 of vibrations detected over time , which is shown in comparison to the nominal characteristic curve 15 in the small diagram . This acquisition curve 16 therefore represents the measured value of the acquired signal over time while the train 300 approaches the insulated rail j oint 101 , passes over the insulated rail j oint 101 and departs from the insulated rail j oint 101 .

Because the cavity 208 leads to increased swings in the acquired values of the signals delivered by the vibration and shock sensor 10 , the system 1 recogni zes that there is a discrepancy in excess of an allowed deviation between the nominal characteristic curve 15 and the acquisition curve 16 .

As a result , the processing stage 3 instructs the communication stage 4 to transmit a delivery data to the central computer to alarm the employee of the railway company about the discrepancies .

Even i f the amplitude curve over time was used for visuali zation in the present case , it should be mentioned at this point that another measure , such as the speci fication of the oscillation frequency or its change , etc . , can of course also be used . Finally, let it be noted once again that the figures described in detail above only involve exemplary embodiments , which the expert can modi fy in a wide variety of ways without departing from the area of the invention . For the sake of completeness , let it also be stated that use of the indeterminate article "a" or "an" does not mean that the respective features cannot be present multiple times .