WO2023079328A1

WO2023079328A1 - Receiverless track circuit for a railway line

Info

Publication number: WO2023079328A1
Application number: PCT/IB2021/000766
Authority: WO
Inventors: Pier-Alessandro Aisa
Original assignee: Alstom Holdings
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2023-05-11

Abstract

A receiverless track circuit (100) for a railway line (110), comprising at least: - a track section (1 ) of said railway line (110) which includes at least a first rail (4) and a second rail (5) having a length (L); the receiverless track circuit (100) being characterized in that it further comprises: - a signal transmitter (20) which is connected to the track section (1) and is arranged to inject a predefined electrical signal (SIN) into one of the first and second rails (4, 5) and to receive in input a return electrical signal (SR) following the injection of said predefined electrical signal (SIN), wherein said signal transmitter (20) is configured to process said return electrical signal (SR) received in input and to output a control signal (Sc), indicative of at least one of a detection of a railway vehicle (120) traveling along the track section (1 ) or of a breakage of at least one of the first and second rails (4, 5), if a value of a selected reference parameter of the return electrical signal (SR) is either higher than an upper threshold (THi) or lower than a lower threshold (TH2) or if the return electrical signal (SR) is not received in input by the signal transmitter 20.

Description

RECEIVERLESS TRACK CIRCUIT FOR A RAILWAY LINE

The present invention relates to a receiverless track circuit for a railway line.

The receiverless track circuit according to the present invention will be described in the following by making reference to main line railway networks, for example for detecting the presence of trains, without intending in any way to limit its possible use with other types of railway applications, such as in tramways and metro lines.

As known, track circuits are apparatuses that each monitor an assigned section of a railway line, typically in order to detect the presence of a train transiting along the assigned section or the occurrence of a broken rail within the same section.

Further, track circuits are also used to communicate data to transiting trains.

The topology of known track circuits foresees the use of a receiver unit and an associated signal transmitter unit which are positioned at the two opposite ends of the assigned sections and operate collaboratively.

Although known track circuits perform adequately the functionalities for which they are devised for, they still present some aspects susceptible of further improvements.

In particular, the fact that for each section of a railway line there is a need of using both a signal transmitter and an associated receiver results in a substantial amount of cost, in particular when considering that a substantial number of track circuits is needed to cover a whole railways line.

This fact has also further negative impacts, such as for example about the quantity of power needed for feeding the installed equipment of each track circuit, about the amount of cabling, as well as of installation, calibration, and maintenance operations.

Hence, the present invention is aimed at mitigating at least some of the above- mentioned issues.

Within this aim, an object of the present invention is to provide a track circuit that, with respect to known solutions, has a constructive layout substantially simplified while being capable of performing the required functionalities at the adequate level of quality.

A further object of the present invention is that of providing a track circuit that, with respect to known solutions, allows reducing the amount of energy required for its functioning, as well as the various operations needed for its installation, calibration and maintenance during its useful life time.

Yet a further object of the present invention is to provide a track circuit which is highly reliable, easy to realize and at competitive costs.

This aim, these objects and others that will become apparent hereinafter are achieved by a receiverless track circuit for a railway line, comprising at least: - a track section of said railway line which includes at least a first rail and a second rail having a length; the receiverless track circuit being characterized in that it further comprises:

- a signal transmitter which is connected to the track section and is arranged to inject a predefined electrical signal into one of the first and second rails and to receive in input a return electrical signal following the injection of said predefined electrical signal, wherein said signal transmitter is configured to process said return electrical signal received in input and to output a control signal, indicative of at least one of a detection of a railway vehicle traveling along the track section or of a breakage of at least one of the first and second rails, if a value of a selected reference parameter of the return electrical signal is either higher than an upper threshold or lower than a lower threshold or if the return electrical signal is not received in input by the signal transmitter.

Further characteristics and advantages will become apparent from the description of some preferred but not exclusive exemplary embodiments of a receiverless track circuit according to the present disclosure, illustrated only by way of non-limitative examples with the accompanying drawings, wherein:

Figures 1 to 3 are views schematically illustrating some possible embodiments of a receiverless track circuit according to the invention;

Figure 4 is a graph schematically illustrating the pattern of the current intensity of a return electrical signal received by a signal transmitter as a function of the position of a train along a track section of the receiverless track circuit according to the invention.

It should be noted that in the detailed description that follows, identical or similar components, either from a structural and/or functional point of view, have the same reference numerals, regardless of whether they are shown in different embodiments of the present disclosure; it should also be noted that in order to clearly and concisely describe the present disclosure, the drawings may not necessarily be to scale and certain features of the disclosure may be shown in somewhat schematic form.

Further, when the term "adapted" or "arranged" or "configured" or "shaped", is used herein while referring to any component as a whole, or to any part of a component, or to a combination of components, it has to be understood that it means and encompasses correspondingly either the structure, and/or configuration and/or form and/or positioning of the related component or part thereof, or combinations, such term refers to.

In particular, for electronic and/or software means, each of the above listed terms means and encompasses electronic circuits or parts thereof, as well as stored, embedded or running software codes and/or routines, algorithms, or complete programs, suitably designed for achieving the technical result and/or the functional performances for which such means are devised.

In addition, when the term “about” or “substantial” or “substantially” is used herein, it has to be understood as encompassing an actual variation of plus or minus 5% with respect to an indicated reference value, axis, time or position, and when the terms “transversal” or “transversally” are hereby used, they have to be understood as encompassing a direction non-parallel to the reference part(s), or position, or direction(s)/axis they refer to, and perpendicularity has to be considered a specific case of transverse direction.

Figure 1 illustrates a first possible embodiment of a receiverless track circuit 100 according to the invention for a railway line 110, which comprises at least a track section 1 having a predetermined overall length L and extending from a first end 2 up to a second opposite end 3.

As those skilled in the art may easily appreciate, the railway line 1 10 can comprise, along its extension, any needed plurality of adjacent track sections, each associated to a corresponding track circuit 100.

For example, in figure 2 there have been illustrated two additional track circuits, indicated by the references 100A and 100B, which are substantially identical to the track circuit 100, and are positioned along the railway line 100, immediately before and immediately after it.

As illustrated in the figures 1 to 3, the track section 1 comprises at least a first rail 4 and a second rail 5 arranged in parallel to form the track section 1 along which a railway vehicle, such as a train, schematically represented only in figure 3 by the reference 120, can transit over.

As illustrated in figure 1 , the rails 4 and 5 are mutually connected to each other by ties or sleepers 6 which extend perpendicularly with respect to the rails 4 and 5 themselves.

The ties or sleepers 6 are laid in the ground and substantially covered with ballast, i.e. small stones, to hold the ties 6 in place.

For ease of illustration, only in figure 1 only two ties 6 have been schematically depicted each at the respective end 2 and 3 of the track section 1 , and the ballast has been represented the reference number 7 only at small areas thereof.

Clearly, ties 6 and ballast 7 have to be considered present also in the embodiments of figures 2 and 3.

Advantageously, the receiverless track circuit 100 according to the present invention comprises also at least a signal transmitter, indicated in figures 1 to 3 by the reference number 20, which is connected to the track section 1 and is arranged to inject a predefined electrical signal SIN into one of the first and second rails 4, 5 and to receive in input a return electrical signal SR following the circulation of the injected electrical signal SIN along the track circuit 1.

In particular, the signal transmitter 20 is configured to process the return electrical signal S received in input, and to output a control signal Sc which is indicative of at least one of the detection of a railway vehicle 120 that is travelling along the track circuit 1 itself, or that at least one of the first and second rails 4, 5 is broken, if a value of a selected parameter of the return electrical signal SR is either higher than a first upper threshold T_HI or lower than a second lower threshold T_H2, or if no return electrical signal SR is received in input, for example after a predetermined amount of time has elapsed since the predefined electrical signal SIN was injected into one of the first and second rails 4, 5.

The control signal Sc can be outputted for example towards a control center of the railway line 110 or of a portion thereof, which is installed in a position remote and has been schematically illustrated only in figure 1 with the reference number 130.

The predefined electrical signal SIN represents in practice a purposive own signature generated by the signal transmitter 20 which is capable of recognizing and discriminating its characteristics from other signals that may be travelling along the rails 2 and 3, for example from equivalents signal injected by adjacent track circuits along the railway line 110.

In practice, according to the invention, the signal transmitter 20 processes in real time the return electrical signal S and, for instance substantially continuously, extracts from it a value of a reference electrical parameter which is compared at the same time with the upper threshold THI and the lower threshold T_H2.

As illustrated in figure 4, if the value calculated for the reference parameter is in the range falling between the upper and lower thresholds (area A in figure 4), then the signal transmitter 20 outputs a signal, for example towards the control center 130 indicating that no train has been detected over the track circuit 1 .

If instead the calculated value of the selected parameter is above the upper threshold THI (area B in figure 4) or below the lower threshold T_H2 (area C in figure 4), or is even zero, namely no return electrical signal SR is received by the signal transmitter 20, then the signal transmitter 20 outputs the above indicated control signal Sc, which is representative of the fact that a train 120 has been detected over the track circuit 1 or that one of the two rails 4 and 5 within the track section 1 is broken.

Usefully, in one possible embodiment, the signal transmitter 20 is configured to select as the reference parameter the intensity of the current of the returned signal and is configured to compare the value of the intensity of the current currently calculated with the upper threshold THI and the lower threshold T_H2. Conveniently, in one possible embodiment, the signal transmitter 20 is further configured to output an information signal SP, for example towards the same control center 130, which is indicative of the actual position of the detected railway vehicle 120 travelling along said track section 1 .

Thus, the signal transmitter 20 can be conveniently exploited for example to indicate the actual position of the train 120 relative to a station along the railway line 1 10; in this way, cross-levels can be operated timely, without introducing unnecessary stop times for road traffic intersecting with the railway line 110.

In one possible embodiment, as for example illustrated for ease of illustration only in figure 1 , the signal transmitter 20 comprises at least:

- a signal processing unit 22 configured at least to process the return electrical signal SR received in input and to calculate values for the selected reference parameter, namely the intensity of the current;

- a power feeding source 24;

- a signal generating unit 26 for generating the predefined electrical signal SIN based on powering signals received for instance from the power feeding source 24; and

- a communication unit 28 configured at least to output the control signal Sc; in the embodiment illustrated, the communication unit 28 is configured also to output the control signal Sc

For example, the signal generating unit 26 can comprise means for generating digital signals, and means for amplifying the signals generated to be injected into the track section 1.

The signal processing unit 22 can be any suitable processor-based device, e.g. a microprocessor, microcontroller, a microcomputer, a programmable logic controller, an application specific integrated circuit, or any other programmable circuit, of a type commercially available, suitably programmed and provided to the extent necessary with circuitry, in order to perform the innovative functionalities devised for the track circuit 100 according to the present invention.

Clearly, as those skilled in the art may easily appreciate, the signal transmitter 20 can comprise any additional component used for performing any other functionality needed, such as e.g. a memory, for storing data, et cetera.

In the illustrative example of figure 1 , the track circuit 100 comprises joint-less rails 4 and 5. In this joint-less configuration, there are no physical interruptions of the rails 4 and 5, and the current loop in the track circuit 100 is achieved basically thanks to the contribution of the ballast resistance.

In this case, the signal transmitter 20 is for instance properly calibrated in order to be assigned and monitor the assigned track section 1 of a predefined length L and, to this end, it can be configured to generate its signature predefined electrical signal SIN, slightly differently from the corresponding signals SIN generated and injected into the railway line 110 by adjacent track circuits 100 A and 100 B.

For example, these respective predefined signals SIN of the track circuit 100, 100A and 100B can be modulated slightly different from each other so as to distinguish among them and to be recognized by the respective generating signal transmitter 20, 20A and 20B.

According to this embodiment, the signal transmitter 20 is conveniently connected to the track section 1 in a position substantially equidistant from the first end 2 and the second opposite end 3 of the track section 1 itself.

According to a second possible embodiment illustrated schematically in figure 2, the track circuit 100 comprises mechanical joints 8 which connect mechanically, at the first and second ends 2 and 3, the rails 4 and 5 of track section 1 with other portions of rails 4 and 5 belonging to two adjacent track sections of the railway line 1 10.

Also in this embodiment, the signal transmitter 20 is conveniently connected to the track section 1 at one of the first or second opposite ends 2, 3 of the track section 1 , for instance at the second end 3 which represents the part of the track section 1 where trains leave the track section 1 itself.

Alternatively, the signal transmitter 20 can be connected to the track section 1 in any other suitable position, for instance in a position equidistant from the two ends 2 and 3.

In this second exemplary configuration, the track circuit 100 is therefore realized as a single insulated track circuit, wherein the mechanical joints 8 maintain the current loop in the track circuit 100, and the track circuit 100 can be assigned to and monitor a longer track section 1 with respect to the track circuit illustrated in figure 1 , e.g. up to a length L up of several hundreds of meters.

According to a third embodiment illustrated in figure 3, the track circuit 100 comprises at least a first inductor 10 which is positioned at the first end 2 of the track section 1 and has a predefined first impedance value; as illustrated, the first inductor 10 has one end 11 connected to the first rail 4 and a second opposite end 12 which is connected to the second rail 5.

According to this second embodiment, the track circuit 100 preferably further comprises a second inductor 13 which is positioned at a second opposite end 3 of the track section 1 and has a predefined second impedance value; likewise the first inductor 10, also the second inductor 13 has one end 14 connected to the first rail 4 and a second opposite end 15 which is connected to the second rail 5.

In this case, as it occurs for the first exemplary embodiment of figure 1 , there are no physical interruptions of the rails 4 and 5, and the current loop in the track section 1 is obtained via the first and second impedances 10 and 13.

According to this third embodiment, the signal transmitter 20 is conveniently connected to the track section 1 at one of the first or second opposite ends 2, 3 of the track section 1 , for instance at the second end 3 which represents the part of the track section 1 where trains leave the track section 1 itself.

In particular, according to a possible variant of this second embodiment, the railway line 110 is an electrified railway line, for example powered by a catenary line non illustrated in the figures, and comprises one or more impedance bonds according to solutions well known in the art and therefore not described herein in further details.

Usefully, according to this variant of the track circuit 100 according to the present invention, at least one of the one or more impedance bonds of the electrified railway lines 110 forms at least one of the first inductor 10 and the second inductor 14.

Preferably, both the first and second inductors 10 and 13 are formed by two corresponding impedance bonds of the electrified railway line 110 positioned at the ends 2 and 3 of the track section 1 .

In this way, already existing components of the railway line 110 meant for other scopes can be usefully exploited also as parts of the track circuit 100.

According to an alternative variant, the first and second inductors 10 and 13 can be constituted by two inductors purposively designed only for being part of the track circuit 100; in this case, with respect to the use of the impedance bonds, such inductors can be properly sized for carrying the current of the signal SIN injected by the signal transmitter 20 and of the related return signal SR whose intensities are lower than the intensity of the traction current of the electrified railway line 110 that has to be carried out by the impedance bonds.

Advantageously, in the track circuit 100 according to the present invention, it is possible to combine, even partially, aspects of the previously described embodiments.

For example, according to a further exemplary configuration, the track circuit 100 according to the invention can be a double insulated track circuit which is equipped with both the impedances 10 and 13 and the mechanical joints 8 as well.

In particular, as illustrated in figure 3 where the joints 8 have been represented with dotted lines, the impedances 10 and 13 are installed each in proximity of the mechanical joints 8 joining the ends of the rails 4 and 5 of the track section 1 with the corresponding rails of adjacent track circuits.

In this case, the mechanical joints 8 will maintain the current loop in the track circuit 100; therefore, the shunting capability is very high and precise in terms of area, without phenomenon like pre-shunt, i.e. a shunting before the first impedance 10, or post-shunt, i.e. a shunting after the first impedance 13.

Also, the variation range of the transmitter current will be limited in a well-defined zone and therefore the track circuit 100 can have a length up to a few kilometres, e.g. 2km, and be compliant with shunt requirements of for example 0.5 ohm and ballast resistance down up to 2 ohm per km.

Hence, it is evident from the foregoing description that the track circuit 100 according to the present invention allows achieving the intended aim and objects since it has a constructive layout substantially simplified with respect to known track circuits while being capable of performing the required functionalities of detecting the presence of trains and the occurrence of a broken rail, in particular a complete breakage, at the adequate level of precision and quality.

Indeed, with respect to known track circuits, the track circuit 100 according to the invention, is realized and performs the basic required functions without using a receiver unit, thus preventing the costs for its realization, its power feeding, as well as related cablings calibration and maintenance operations.

These results are achieved according to a solution which is simple to be implemented and can be used in a very flexible way to realize different configurations with different performances, for instance in terms of track circuit shunt sensitivity, length, and ballast parameters.

Further, by properly configuring the signal transmitter 20, the track circuit 100 can be exploited also for communicating the actual position of a train 120 along the track section 1.

For example, as schematically illustrated in figure 4 which refers to the third embodiment of the track circuit 100 illustrated with reference to figure 3, when a train 120 is detected as entering the track section 1 , the current raises, substantially linearly, up to when the first axle of the train 120 reaches the position at which the signal transmitter 20 is connected to the track circuit 1. Then, the intensity of the current remains substantially constant up to when the last axle of the train 120 passes over the connection position of the signal transmitter 20. Then, if the connecting position is for example in the middle of the track section 1 , the intensity of the current decreases, substantially linearly, up to when the train 120 leaves completely the zone assigned to the track circuit 100. If instead the signal transmitter 20 is connected at one end of the track section 1 , e.g. at the second end 3, then, the value of the intensity of the current decreases almost instantaneously from the constant value to a value which is between the upper and lower thresholds T and THS, unless there is a broken rail condition. Hence, the position of the train 120 can be localized based on the actual value of the intensity of the current.

The receiverless track circuit 100 thus conceived is susceptible of modifications and variations, all of which are within the scope of the inventive concept as defined in particular by the appended claims; for example, instead of selecting the intensity of the current as reference electrical parameter, it is possible to select a different one, e.g. the frequency, the phase, et cetera.

All the details may furthermore be replaced with technically equivalent elements.

Claims

CLAIMS A receiverless track circuit (100) for a railway line (1 10), comprising at least:

- a track section (1 ) of said railway line (110) which includes at least a first rail (4) and a second rail (5) having a length (L); the receiverless track circuit (100) being characterized in that it further comprises:

- a signal transmitter (20) which is connected to the track section (1) and is arranged to inject a predefined electrical signal (SIN) into one of the first and second rails (4, 5) and to receive in input a return electrical signal (SR) following the injection of said predefined electrical signal (SIN), wherein said signal transmitter (20) is configured to process said return electrical signal (S ) received in input and to output a control signal (Sc), indicative of at least one of a detection of a railway vehicle (120) traveling along the track section (1) or of a breakage of at least one of the first and second rails (4, 5), if a value of a selected reference parameter of the return electrical signal (SR) is either higher than an upper threshold (THI) or lower than a lower threshold (TH2) or if the return electrical signal (SR) is not received in input by the signal transmitter 20. The receiverless track circuit (100) according to claim 1 , wherein said signal transmitter (20) is configured to select as reference parameter the value of the intensity of the current of the return electrical signal (S ) and to compare it with both said upper threshold (THI) and said lower threshold (T_H2). The receiverless track circuit (100) according to any of the claims 1 to 2, wherein said signal transmitter (20) is further configured to output an information signal (SP) indicative of the actual position of a railway vehicle (120) detected as travelling along said track section (1 ). The receiverless track circuit (100) according to one or more of the previous claims, wherein it further comprises at least a first inductor (10) which is positioned at a first end (2) of the track section (1 ) and is connected at one end (11 ) to said first rail (4) and at a second opposite end (12) to said second rail (5), said first inductor (10) having a predefined first impedance value. The receiverless track circuit (100) according to claim 4, wherein it further comprises a second inductor (13) which is positioned at a second opposite end (3) of the track section (1 ) and is connected at one end (14) to said first rail (4) and at a second opposite end (15) to said second rail (5), said second inductor (13) having a predefined second impedance value. The receiverless track circuit (100) according to claim 4 or 5, wherein said signal transmitter (20) is connected to the track section (1 ) at one of said first end (2) or second opposite end (3) of the track section (1). The receiverless track circuit (100) according to one or more of the claims 5 to 6, wherein the railway line (110) is an electrified railway line and comprises one or more impedance bonds, at least one of said one or more impedance bonds forming said first inductor (10) and/or said second inductor (14). The receiverless track circuit (100) according to one or more of the previous claims, wherein the track section (1 ) comprises mechanical joints (8) for mechanically connecting the track section (1 ) with two adjacent track sections of said railway line (110). The receiverless track circuit (100) according to one or more of the claims 1 to 7, wherein said first and second rails (4, 5) of the track section (1) are joint-less, and wherein said signal transmitter (20) is connected to the track section (1) in a position substantially equidistant from a first end (2) and a second opposite end (3) of the track section (1) itself. The receiverless track circuit (100) according to one or more of the previous claims, wherein said signal transmitter (20) comprises at least:

- a signal processing unit (22) configured at least to process said return electrical signal (SR) received in input and to calculate values for said reference parameter;

- a power feeding source (24);

- a signal generating unit (26) for generating said predefined electrical signal (SIN) based on power signals received from the power feeding source (24);

- a communication unit (28) configured at least to output said control signal (Sc).

RECEIVERLESS TRACK CIRCUIT FOR A RAILWAY LINE

ABSTRACT

A receiverless track circuit (100) for a railway line (1 10), comprising at least:

- a signal transmitter (20) which is connected to the track section (1) and is arranged to inject a predefined electrical signal (SIN) into one of the first and second rails (4, 5) and to receive in input a return electrical signal (SR) following the injection of said predefined electrical signal (SIN), wherein said signal transmitter (20) is configured to process said return electrical signal (S ) received in input and to output a control signal (Sc), indicative of at least one of a detection of a railway vehicle (120) traveling along the track section (1 ) or of a breakage of at least one of the first and second rails (4, 5), if a value of a selected reference parameter of the return electrical signal (SR) is either higher than an upper threshold (THI) or lower than a lower threshold (TH2) or if the return electrical signal (SR) is not received in input by the signal transmitter 20.

Figure: 1