AU2014202937A1 - Device for measurement and management of the mechanical tension of a long welded rail - Google Patents

Abstract

A device for detection of the mechanical tension and temperature of at least one rail (10) of a railway line (1), comprising: a plurality of mechanical tension and temperature detection sensors (2, 2A, 2B, 2C, 2D) installed on the rail (1) together with the relative electronic means (21-26) necessary for data acquisition; centralising devices (4) adapted to receive data from all the sensors (2, 2A, 2B, 2C, 2D) placed along the line (1) by means of the relative data trans receiver means (3), said centralising devices (4) being adapted to group together the data received from several sensors which are in a specific area; a central station (6) connected to said centralisers (4) by means of the relative data trans receiver means (5); the central station (6) being equipped with processing means (43, 44) where the data transmitted by the centralising devices (4) is reprocessed, in order to detect tension and/or thermal situations indicating degraded conditions of safety of the railway infrastructure, for example rail close to misalignment or breakage, or degradation of the ballast or track body, and the consequent generation of an alarm displayed to the operator by means of a graphic and acoustic interface (42) located in the central station (6). 2 2' -- ---- --- y 4--- ----- --- -- --- ------- 10ig 1 2b 12 Fig,2c

Description

1 DEVICE FOR MEASUREMENT AND MANAGEMENT OF THE MECHANICAL TENSION OF A LONG WELDED RAIL FIELD OF THE INVENTION [0001] The object of the present invention is realising a diagnostics system for situations of danger for railway traffic caused by breakage of the rail due to contraction, misalignment from elongation, yielding of the infrastructure, by means of detection, transmission to a remote station and processing of the mechanical tension and temperature of the rail. BACKGROUND OF THE INVENTION [0002] The railways adopted some time ago the technique of the long welded rail (LWR), i.e. long stretches of rail welded to each other, which reduces maintenance and improves travelling comfort. Due to thermal excursion, movements caused by expansion or shrinking may occur at the ends of the LWR. Installation of the LWR is therefore carried out imposing the rail mechanical tension as zero at the "regulation temperature", which is a function of the arithmetic average between the maximum and minimum rail temperatures over the last 3 years and corrective factors. [0003] The thermal load which stresses the rail depends on the difference between the regulation temperature and the actual temperature. An excessive positive thermal load may cause misalignment of the rail, an excessive negative thermal load may lead to breakage of the rail. The thermal load is the only stress to which the rail is subjected in ideal maintenance conditions and in the absence of trains in transit. The checks conducted until now have therefore been limited to measuring the temperature of the rail and controlling the rail geometry.

2 [0004] Control of the temperature checks that the thermal load on the rail does not reach alarm values, while the check on rail geometry checks that no movements of the rail are present. [0005] The following are on sale for these purposes: systems which measure the rail temperature and transmit the measurement to a central station via cable; systems capable of detecting movements of the rail with respect to fixed points of reference (requiring operators in loco). [0006] However, misalignment and breakage of the rail are events which cannot be predicted by measuring solely the temperature and, periodically, the geometry of the rail: measuring the temperature does not identify other parameters, such as degradation of the ballast or a change in the neutral reference temperature of the rail (temperature at which mechanical tension is zero). [0007] The actual neutral temperature of the rail does, in fact, change over time, making the reference value for calculation of a dangerous thermal head indeterminate. [0008] In conclusion, situations of degradation of the ballast, or landslips underneath the track body cannot be detected solely by measuring the rail temperature. [0009] It is therefore opportune to consider measuring the mechanical tension of the rail, for which products are on sale which may be classified according to the measurement method. [0010] The most simple, but also most invasive, products require cutting of the rail and measurement of the rail deformations after cutting, so they cannot be considered for purposes of continuous diagnostics of the rail. [0011] A second category includes devices to be installed momentarily on the line or transportable by truck, which detect the tension of the rail and use this to calculate the current regulation temperature in real time. These may only operate periodically and require rail traffic to be halted to take the measurements.

3 [0012] The last category contains devices installed permanently on the rail which measure the mechanical tension, but cannot take purely mechanical deviations into account. [0013] The object of the present invention is providing in real time in a remote station, without field operators, continuous detections of mechanical tension and temperature of the rail; performing smart diagnostic processing and post-processing of said data by associating the tension state with evolution of the temperature with respect to the current neutral temperature, so as to generate alarms automatically in situations of danger. [0014] The system architecture is designed so as not to interfere with railway traffic and maintenance of the infrastructure. [0015] The primary function of the system is collecting and transmitting the data measured to a remote processing station, passing through centring devices dedicated each to a specific zone of the line. [0016] The second function is processing the data to identify, but also to predict situations of danger for traffic, such as misalignments (elongation due to high temperature), breakage of the rail (shortening due to low temperature), yielding of the infrastructure (elongations without an increase of the temperature). [0017] An important function is therefore signalling situations of danger to a railway operator, identifying the type and level of danger so as to guarantee prompt intervention. [0018] The object of the present invention is realised through temperature and mechanical tension sensors, installed directly on the rail. In order not to interfere with infrastructure maintenance operations, transmission of data is realised, for example, via wireless or via cable and power is supplied by batteries, for example, also installed on the rail or on the sleeper.

4 [0019] The sensors detect the state of tension of the rail in the longitudinal, vertical and flexural direction. The system receives, acquires and checks the mechanical tension in relation to the expected range and, if necessary, generates alarms. [0020] Data centralisers are installed along the line to limit the wireless or cable transmission distance and group together the data from several sensors for a specific area. The data collected by the centralisers is transmitted to the central station in a remote position, for example via a GSM connection, via fibre-optics, satellite transmission or another available transmission channel. [0021] The remote position acquires, stores and processes the data in real time and creates an historical log to analyse performance over time. [0022] The following detailed description of the invention referring to the appended drawings, provides further clarifications and is to be considered as a non-limiting example: [0023] Fig. 1 shows the general functioning diagram of the system; the sensors are installed along the railway line organised into groups, each of which transmits the data via wireless or via cable to a local centraliser of reference. Each centraliser transmits the data to a central station, for example by means of a GSM connection, via fibre-optics, satellite transmission or another available transmission channel; [0024] Figs. 2a, 2b, 2c respectively show a front view, a side view and a perspective view of a rail where sensors to measure longitudinal, vertical and flexural mechanical tension are installed, grouped inside a single container; [0025] Fig. 3 shows a functioning diagram of the sensors installed along the rails and the electronics associated with them. In particular, it is shown how measurements are taken and managed for purposes of transmission to the centraliser. [0026] Fig. 4 shows a distribution diagram of the components installed along the railway line, in which the sensors to be installed on the rail are protected by a metal casing which also contains the electronics necessary for reading the data, while on the sleeper 5 another box will be installed containing the remaining electronics, which are responsible for data transmission, and any battery for system power supply; in particular conditions, the elements for data transmission and any battery may all be contained in the box assembled on the rail; [0027] Fig. 5 shows a functioning diagram of the data centraliser, in particular the transmission modules of the data to the railway line and to the central station; [0028] Fig. 6 shows a diagram of the functioning principle of the central station, in particular how the data is managed; [0029] Fig. 7 shows another general summary functioning diagram of the system which is the object of the invention; [0030] Fig. 8 shows a flow diagram relating to functioning of the system in the particular configuration for prevention of misalignment conditions or breakage of the rail; [0031] Fig. 9 shows a flow diagram relating to functioning of the system in the particular configuration for prevention of situations of degradation of the ballast, railway platform and landslips. [0032] With reference to said appended drawings and with particular reference to fig. 1, the number 1 denotes the section of railway line, in particular the so-called long welded rail (LWR), on which sensors 2 are installed for detection of the mechanical tension and/or the temperature. Said line comprises two rails 10 and sleepers 8 connecting them. Depending on the configuration it is intended to chose, the sensors 2 may be installed only on one rail or on both, and this choice allows a comparison to be made between the behaviour of the two rails. [0033] Close to each sensor 2, all the electronics are installed which are necessary to perform measurement and transmit data to a centralising device 4 via data transmission means 3, which may be a wireless network or normal data transmission cables. The centraliser 4 receives the data from a certain number of sensors 2 in a specific area, thus creating data sets, said data is stored by the centraliser until it is transmitted to the central 6 station 6. Transmission between the centralisers 4 and the central station 6 occurs, for example, by means of a GSM-R type network 5, but may also take place by means of a fixed network, satellite or with other means. Said central post 6 may be, for example, an operating room where the data received is stored and processed and from where the entire system is normally managed. [0034] Figs. 2a, 2b, 2c show a front, side and perspective view of a rail 10 of the line 1 on which mechanical deformation sensors 2A, 2B, 2C are installed, for example strain gauges and thermal sensors welded to them. In particular, sensors 2A and 2B are installed on the web 11 of the rail 10, while sensor 2C is installed on the flange 12 of the rail. [0035] Installation of the strain gauge 2A in the horizontal position close to the neutral axis N detects the longitudinal tension of the rail and deformations due to the thermal load. As the temperature changes, the rail 10 will tend to elongate or contract as a function of the link between tension and temperature. The sensor 2A assembled in this position monitors the mechanical tension continuously and detects misalignments and breakages of the rail. [0036] Installation of the strain gauge 2B in a vertical position, with respect to the neutral axis N, detects deformations due to the transit of trains and therefore the vertical state of tension of the rail. [0037] Installation of the strain gauge 2C on the flange of the rail 10 detects the flexural deformations of the rail. In nominal conditions of the infrastructure, said deformations are absent, so detection is important as it indicates degradation of the ballast or the track body. [0038] In addition to the strain gauges 2A, 2B, 2C, a temperature sensor is also positioned, used to assess performance of the mechanical tension as a function of temperature.

7 [0039] As illustrated in fig. 2C, the strain gauges 2A, 2B, 2C and the temperature sensor may be housed inside a container 7 where the devices and means of data transmission to the centraliser and therefore to the central station may also be positioned. [0040] The system functioning diagram of fig. 3 shows, for example, two strain gauges 2A, 2B, and a temperature sensor 2D. Said sensors are resistors, the value of which changes as a function of the deformation sustained. Each sensor is connected, for example, by means of the relative cables 18, 19, 20, to a Wheatstone bridge 17 which transforms the change in resistance into a change in electrical voltage. The Wheatstone bridge is located in a metal box 15 assembled close to the sensors 2A, 2B, 2D. [0041] In order to limit the weight of the system on the rail, the remaining necessary circuits and the battery may be placed in a further box 27 assembled on the sleeper; in this case, the connection between the two boxes 16 and 27 is guaranteed by a cable which supplies electrical power and transmits the measurements coming from the sensors 2A, 2B, 2D. As seen above with reference to fig. 2c, all the elements shown in fig. 3 and contained in the boxes 16 and 27 may be enclosed in a single box 7. [0042] The electrical signal coming from the sensors 2A, 2B, 2D is amplified by means of a precision amplifier 21, the output of which is connected incoming to an A/D analogue/digital converter 22, which transfers the signal to a micro-controller 25. [0043] A memory 24 maintains the data awaiting periodic transmission by means of a high-efficiency specific wireless module 26 to limit energy consumption, or with a cable; the long-lasting battery 23 guarantees power supply. The power supply of the system may be, alternatively or in combination with the battery 23, also with power supply brought in loco by means of a specific electrical cable, or by means of a solar panel or vibration-based energy storage systems. [0044] As shown schematically in Fig. 4, the various devices to be arranged along the rail 10 are positioned between said rail 10 and the sleeper 8. The sensors are covered by the metal box 16 which also contains the Wheatstone bridge; the remaining electronic components are contained in the box 27 to be installed on the sleeper 8. In contrast, the box 8 16 will be installed on the rail 10. Boxes 16 and 27 are connected by a cable 9 equipped with connectors. In particular configurations, all the electronic components may be contained inside the box 16. [0045] The modules installed on the track dialogue, by means of the wireless network 3 or the cables, with the data centraliser 4. Said centraliser 4, see Fig. 5, is formed of a wireless module 40 for communication and receiving of data from the measurement points, or by a cable connection, therefore by the sensors, managed by a micro-processor 39 which stores the data in a specific memory 37. The microprocessor 39 also manages data transmission to the central station 6 by means of a module GSM-R 41, or alternatively, a connection by means of an Ethernet network or satellite transmission. The centraliser 4 is provided with a special power supply 38. [0046] The data management central station 6, see Fig. 6, is provided with a receiving module (GSM-R or Ethernet or satellite) 45, a data processor 43 which implements the data processing algorithm and the calculation functions on the acquired data, stores the data in a database 44 and displays on a video monitor 42 the information and any alarm notices to the user. [0047] The present invention therefore operates on three levels, see Fig. 7: at rail level by means of a device 29 of conditioning, conversion and acquisition of the data received from the sensors 2. These signals are transformed into digital signals and transmitted to the higher level by means of the wireless network 3 or via cable. A second intermediate level where the data is received by means of an analogue wireless module or via cable 3, by a centraliser 4 which acquires and manages the data by means of a microprocessor and then sends it to the higher level by means of a dedicated network 5 (Ethernet, GSM-R, satellite or other) to the central station 6. The central station 6 is the higher level where an analogue communication module receives the data and sends it to the calculation unit, where the data is processed and stored. At the central station 6, the graphic interface 42 allows display of any alarm signals and all the data acquired. [0048] For each point of the line 1 where the present system is installed, the data is processed by the central station 6 in a manner to correlate the independent mechanical 9 tension and temperature measurements. The system is usable in at least two different configurations for detection of the state of longitudinal tension and for detection of yielding of the ballast or landslips. [0049] Fig. 8 shows the block diagram of functioning for the system configured for control of longitudinal tension, in order to generate alarms in the case of conditions close to breakage or misalignment of the rail. In this configuration, the temperature, block 46, is detected by means of the sensor 2D, and rail deformations, block 47, by means of the sensor 2A, from which mechanical tension is determined, block 48. The data measured and stored in the database is correlated, block 49, checking that the link between the two quantities is linear and calculating the coefficient which links them. After a first system calibration phase, characterisation of each measurement point is obtained; from that moment, all the measurements must comply with the characteristic link and the predisposed maximums/minimums range. This configuration generates alarms in the following cases, block 50: - mechanical tension value too high, a situation which presages a possible misalignment; - mechanical tension value too low, a situation which presages a possible breakage; - sudden increases in tension, movements of the rail with consequent change of the geometry; - link between mechanical tension and temperature not satisfied, possible problems with the state of the ballast; - mechanical tension not zero at the regulation temperature, possible deregulation of the rail. [0050] Fig. 9 shows the block diagram of functioning for the system configured for control of vertical and flexural tensions, for identification of problems of the infrastructure such as yielding and landslips: the vertical mechanical tension, block 51 (sensor 2B), and the flexural mechanical tension of the rail are detected by means of the sensor 2C, block 52; the data measured is transmitted and filed in the database, then correlated, block 53, by associating the flexural state of the rail with transit of the trains, detected by the vertical tension sensor 2B. The relative alarms are generated in the following cases, block 54: - flexure value which increases, in a limited manner, each time following 10 passage of a train, possible degradation of the ballast or the track body: - non-restoral of the initial flexure value after transit of a train, possible degradation of the ballast or the track body or landslip; - sudden increase of rail flexure without any transit of trains, landslip in progress. [0051] The alarm signals occur by means of a visual and acoustic communication to the central station 6 which indicates which event has generated the dangerous situation. [0052] For each of the aforesaid conditions, the device operates predictively by anticipating from performance any situations of potential danger and generating the relative alarm displayed to the manager, who takes the necessary actions according to current regulations. [0053] Furthermore, the present invention also assists rail regulation, allowing rail temperature and tension to be checked continuously, so as to guarantee that the rail itself is correctly freed from restrictions, reaching a zero state of tension, to then be replaced in tension at the correct value in accordance with the desired regulation temperature. [0054] Taking the system safety level to the signalling level is also possible by interfacing with it, in order to intervene, automatically and without human intervention, on train traffic at the moment when dangerous conditions caused by the state of the track, such as misalignments or breakages, are detected. [0055] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. [0056] The reference to any prior art in this specification is not and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia.

Claims (18)

1. A device for detection of the mechanical tension and temperature of at least one rail of a railway line, comprising: a plurality of mechanical tension and temperature detection sensors installed on the rail together with the relative electronic means necessary for data acquisition; centralising devices adapted to receive data from all the sensors placed along the line by means of the relative data trans receiver means, said centralising devices being adapted to group together the data received from several sensors which are in a specific area; a central station connected to said centralisers by means of the relative data trans receiver means; the central station being equipped with processing means where the data transmitted by the centralising devices is reprocessed, in order to detect tension and/or thermal situations indicating degraded conditions of safety of the railway infrastructure, for example rail close to misalignment or breakage, or degradation of the ballast or track body, and the consequent generation of an alarm displayed to the operator by means of a graphic and acoustic interface located in the central station.

2. The device according to claim 1, characterised by said sensors comprising strain gauges, opportunely installed on the web and/or on the flange of the rail, in order to detect longitudinal tensions, mostly associated with the thermal load, vertical tensions, mostly associated with the transit of trains, flexural tensions, mostly associated with transit of trains in conditions of degradation of the ballast, and thermal resistances for determination of the temperature of said rail, conditioning of the signal of said sensors, analogue-digital conversion and transmission by said means being realised close to them, with devices installed on the rail and/or on the sleeper.

3. The device according to claim 1, characterised by comprising at least one sensor placed in a horizontal direction on the web of the rail for detection of deformations due to thermal load and/or at least one sensor placed in a vertical direction on the web of the rail for detection of the deformations due to transit of trains.

4. The device according to claim 1, characterised by comprising at least one sensor placed on the flange of the rail for detection of flexural deformations due, for example, to degradation of the ballast or the track body. 12

5. The device according to claim 1, characterised by data transmission being possible by means of a low energy consumption wireless network, which does not require cabling of any cable between the centralisers and the devices installed along the line.

6. The device according to claim 1, characterised by data transmission being possible, alternatively to the wireless connection, by means of cables between the centralisers and the devices along the line.

7. The device according to claim 2, characterised by all the devices installed along the line being supplied power by long-life batteries or other means such as solar panels, vibration-based energy storage systems or by means of an electricity supply cable from the fixed network.

8. The device according to claim 2, characterised by said data centralisers being placed along the line and collecting by means of wireless network, or by means of cable, data from devices along the line, and retransmitting it to the remote station, i.e. to the central station, by means of GSM-R terminals or Ethernet cards or satellite transmission.

9. The device according to claim 1, characterised by comprising a first container in which are installed the tension and temperature sensors and a second container in which are placed the electronic elements necessary for acquisition and management of the data from the sensors.

10. The device according to claim 2, characterised by comprising a single container applied to the rail where the sensors and the relative electronic means of data transmission and management are placed.

11. The device according to claim 1, characterised by the centraliser comprising a microprocessor, an electric power source and a data storage memory.

12. The device according to claim 1, characterised by said electronic means comprising an amplifier, an analogue/digital A/D converter, an electric power source, a data storage memory, a micro-controller and a communication module. 13

13. The device according to claim 1, characterised by each sensor being connected to a Wheatstone bridge which transforms the change in resistance into a change in electric voltage.

14. The device according to claim 1, characterised by the central station being equipped with a processor of data coming from the sensors installed along the rails, memory and graphic interface, said processing device being able to determine the characteristic tension - temperature of each measurement point, check that the tension and temperature values measured are within the maximum values and conform with the expected ones, and if necessary to generate an alarm signal to the user.

15. The device according to claim 13, characterised by said processing device of data coming from the sensors installed along the rails being capable of determining the characteristic train - rail flexure at every point of measurement, checking that the flexure values conform with the expected ones in good ballast conditions.

16. The device according to any one of the previous claims, characterised by being able to generate alarms, displayable on the central station, in the case of degradation of safety of railway traffic, with indication of the type of alarm and the kilometre where the event has occurred.

17. The device according to any one of the previous claims, characterised by being able to supply support to the rail regulation activity by means of continuous control of two characteristic parameters; longitudinal mechanical tension and temperature of the rail, displaying in real time the state of the two quantities and the regulation temperature at the end of the operations.

18. The device according to any one of the previous claims, characterised by being able to interface, if taken to the same safety level, with signalling, so as to intervene, automatically and without human intervention, on train traffic at the moment when dangerous conditions caused by the state of the track, such as misalignments or breakages, are detected.