EP0050535B1 - Railway track circuit - Google Patents

Abstract

A railway track comprising a pair of rails is divided into a succession of segments, each segment having a railway track circuit for separating successive trains. The track circuit is switchable between an initial state and a complementary state and comprises a downstream impedance electrically connecting the rails at a downstream point, an upstream impedance electrically connecting the rails at an upstream point, an electromagnetic sensor located between the upstream and downstream impedances in the vicinity of one of the rails, a transmitting member, and a pair of receiving members. One receiving member is in electromagnetic communication with the electromagnetic sensor. The transmitting member and the other receiving member are switchable between connection to the downstream impedance and the upstream impedance.

Description

The present invention relates to a railway track circuit, constituted by the two rails of a portion of railway track and comprising a transmitting member connected to the downstream end of the circuit and a receiving member connected to the end upstream.

We know that the safety and regularity of trains running on railway tracks depends, among other conditions, on the distance separating two successive convoys on the same track, taking into account the admissible speed as a function of the braking characteristics of trains. and the line profile.

The information necessary for the train driver to initiate actions to ensure this safety and regularity can be transmitted to fixed points on the route by lateral signals spaced along the tracks. They can also, in substitution or reinforcement of the lateral signaling and when it concerns automatic driving or controlled manual driving, be transmitted directly and in all points of the track towards the machine.

In general, at present, these are safety devices called "track circuits", which make it possible to develop and transmit the information necessary for safety, security and regularity of traffic, also in side signal systems as in a certain number of systems implementing information transmission methods from the track to the machine.

In a manner known per se, the track is divided into a succession of cantons, each canton being equipped with a track circuit. In its most general form, a track circuit consists of a transmitter and a receiver, each located at one end of the track circuit, and connected to the rails, so that an axle shunt located between the point of emission and the point of reception of the channel causes the de-excitation of a relay associated with the receiver. In the case of a track circuit associated with side signals, the relative position of the transmitter and receiver of the track circuit vis-à-vis the entry and exit of the block is immaterial, since only account the presence or absence of a shunt axle on the block. It is not the same in the case where the track circuit is used in a system with transmission of information from the track to the train. In such a system, the train receives the information by capturing the electromagnetic field radiated by the rails, a field existing due to the circulation of the signaling current in each of the rail nets. The receiving device on board the train must therefore, in principle, be permanently between the sending device and the first shunt axle of the train. It obviously follows that in this case, the transmitting member must always be connected to the downstream end of the track circuit, while the receiving member is connected to the upstream end.

In networks where the density of traffic is one of the dominant elements, such as urban networks, the spacing signaling must be designed in such a way as to minimize the distance between two successive convoys and to be reduced as much as possible train stop times in front of a closed signal. It is therefore advantageous to be able to open this signal in anticipation of the clearance, by the occupying train, of a canton situated downstream, while keeping between the signal to be opened and a critical point of the canton in the process of being cleared, a length of clear lane corresponding to the braking limit distance in the most unfavorable conditions. It is necessary, to carry out such anticipation, to know with all the required security the position of the whole train with respect to the two ends of the block it occupies and / or with respect to any critical points.

However, in the known systems of the prior art, the need to simultaneously locate the first shunting axle of the train (head of the train) and the last shunter axle of the train (tail of the train) in order to know the relative position of the whole of the convoy vis-à-vis the two ends of the block and / or a particular point leads to an incompatibility between track circuit and transmission of information from the track to the machine.

The main object of the present invention therefore is to remedy this drawback and to do this it relates to a track circuit of the aforementioned type which is essentially characterized in that it also comprises at least one electromagnetic sensor disposed at a determined location along the track circuit, a receiver associated with this sensor and switching means for switching the transmission and reception members of the track circuit, after the receiver associated with the sensor has been de-energized by the passage over said sensor of the first shunter axle carried by the train running on the track.

Thanks to this arrangement, it is possible, as will be seen more clearly later, to detect the passage of the last shunting axle of the train at a particular point on the track circuit materialized by the sensor, without interrupting the transmission. information between the track and the machine, the detection of the last shunt axle resulting in the re-excitation of the receiver associated with the sensor.

However, it appears that such an arrangement can lead to a premature re-energization of said receiver, in the case where the interval existing between two contiguous axles of the train is greater than the distance separating the sensor from the upstream end of the track circuit where is located connected the transmitter.

To remedy this situation, the track circuit, assumed to be of the type with electrical separation seals, that is to say without insulating seals, comprises a second sensor disposed upstream of the first and beyond the corresponding end of the track circuit, at a distance therefrom greater than the maximum interval existing between two contiguous shunt axles of trains capable of running on the track, this second sensor being associated with a receiver sensitive to the operating frequency of the track circuit considered.

Thus, the early release information, corresponding to the detection of the last shunt axle, will only be delivered when the receivers associated with the two sensors are simultaneously de-energized.

Preferably, the second sensor is located in the middle area of the electrical separation joint and it is associated with a second receiver sensitive to the operating frequency of the track circuit located upstream.

It is thus possible to take advantage of the presence of this second sensor to precisely determine the position of the "fictitious joint" entering the track circuit and to check the release of the entire area occupied by the joint.

According to another characteristic of the invention, the track circuit comprises an additional transmitting member which is connected in place of the receiving member as soon as the receiver associated with the sensor is de-energized, while the transmitting member original remains connected to the downstream end of the track circuit.

Thanks to this arrangement, it is always possible to detect the last axle, even in the case of very short trains or very long track circuits. In the absence of an additional transmitting member, it is indeed necessary, in order not to interrupt the transmission of information between the track and the machine, to switch the transmitting and receiving members only when the first axle has past the downstream end of the track circuit in question. However, it may be that at this instant, the last axle has already passed over the sensor, if the distance separating the sensor from the downstream end of the track circuit is greater than the length of the train.

According to yet another characteristic of the invention, several electromagnetic sensors, each associated with a receiver, are distributed along the track circuit, the original transmission member being connected successively over time, immediately downstream of the various sensors, then at the downstream end of the track circuit, as the train advances in said track circuit.

It is thus possible to simultaneously detect the first axle and the last axle of the train, while improving the conditions for transmitting information between the track and the machine, since the distance between the head of the train and the transmitter is reduced.

• - la figure 1 est un schéma synoptique d'un circuit de voie équipé conformément à l'invention;
• - la figure 2 est un schéma synoptique illustrant une application de l'invention à l'exploitation d'une portion de réseau comprenant des gares successives;
• - la figure 3 est un schéma synoptique d'une première variante de réalisation de l'invention;
• - la figure 4 est un schéma synoptique d'une deuxième variante de réalisation de l'invention; et
• - la figure 5 est un schéma synoptique d'une troisième variante de réalisation de l'invention.

Several embodiments of the invention are described below by way of examples, with reference to the accompanying drawings in which:

• - Figure 1 is a block diagram of a track circuit equipped in accordance with the invention;
• - Figure 2 is a block diagram illustrating an application of the invention to the operation of a portion of network comprising successive stations;
• - Figure 3 is a block diagram of a first alternative embodiment of the invention;
• - Figure 4 is a block diagram of a second alternative embodiment of the invention; and
• - Figure 5 is a block diagram of a third alternative embodiment of the invention.

The track circuit shown in the diagram in FIG. 1 is of the type with electrical separation seals, also known as a track circuit without seals, that is to say without insulating seals. It is essentially constituted by the two rows of rails r ₁ and r ₂ of a portion of railway track electrically bounded by two electrical separating joints J, and J ₂ . These joints are respectively materialized by the impedances Z ₃ , Z, and Z ₂ , Z ₄ . It is further assumed that the trains are moving on the track in the direction indicated by the arrow F.

In a manner known per se, the signaling current flowing in the track circuit thus defined is at a first frequency F _i , while the signaling current flowing in the track circuits located respectively upstream and downstream of the track circuit considered at a second frequency F ₂ different from F ₁ . This signaling current at the frequency, F, is generated by a transmission member E _v which is normally connected to the downstream end of the track circuit, ie at the terminals of the impedance Z ₂ . In the absence of a shunt axle on the track circuit considered, this transmission member Ev makes it possible to exist a reception member R _v sensitive to the frequency F _i which is normally connected to the upstream end of said circuit, ie across the impedance Zi.

According to the invention, the track circuit further comprises an electromagnetic sensor C ₁ , placed on the ground near one or the other of the two rows of rails r _i and r ₂ , at a point P ₁ of the circuit located at a distance d _i from the impedance Z _i . This sensor Ci, which can be of any known type, makes it possible to transform the surrounding field due to the signaling current flowing in the rails r ₁ , r ₂ into a voltage of the same frequency and of amplitude proportional to the intensity of this current . It is therefore associated with a receiver R _c , sensitive to the frequency F _i of the track circuit considered.

A switching device or switch COM is also provided to reverse the position on the channel of the transmitter E _v and the receiver R _v . In other words, depending on the state of this switching device, it will be possible to meet the receiver R _v at the upstream end of the circuit (connected to the terminals of the impedance Z _i ) and the transmitter E _v at the downstream end of the circuit (connected to the terminals of the impedance Z ₂ ) or vice versa. The COM switching device is controlled by a LOG switching logic which itself receives orders from an information processing device. IT department which centralizes information from the different reception points located along the track circuit. In this case, it is information originating respectively from the channel circuit receiver R _v , from the receiver R _c , associated with the sensor Ci and from a receiver R sensitive to the frequency F ₂ which is connected across the terminals of the 'impedance Z ₄ constituting the upstream end of the track circuit located downstream of the track circuit considered.

• Au départ, le circuit de voie est dans son état initial défini par une position du commutateur COM telle que le récepteur Rv se trouve connecté aux bornes de l'impédance Z₁ et l'émetteur E_v aux bornes de l'impédance Z₂. De plus, aucun essieu shunter ne se trouve sur la portion de voie considérée, de sorte que les récepteurs R_v, R_c, et R sont tous les trois excités.

The track circuit which has just been described operates as follows:

• At the start, the track circuit is in its initial state defined by a position of the switch COM such that the receiver Rv is connected to the terminals of the impedance Z ₁ and the transmitter E _v to the terminals of the impedance Z ₂ . In addition, no shunter axle is located on the portion of track considered, so that the receptors R _v , R _c , and R are all three excited.

Suppose now that a train is moving on the track, in the direction indicated by the arrow F, from the track circuit located upstream to the track circuit located downstream, passing through the track circuit considered. When the first shunt axle of the train enters the input joint Ji, and for a variable position of the latter inside said joint, the receiver R _v connected to the terminals of the impedance Z ₁ de-energizes. Then, when the first shunting axle crosses the point P _l where the sensor Ci is located, the associated receiver R _c , in turn becomes de-energized due to the derivation in the shunting axle of all or part of the signaling current generated by the transmitter Ev.

Finally, the first shunt of the train enters the output joint J ₂ and causes the receiver R to be de-energized. At this instant, the information processing device TI causes, by means of the switching logic LOG, the passage of the switch COM in the state complementary to its initial state, the transmitter E _v being therefore connected to the terminals of the impedance Z ₁ while the receiver R _v will be connected to the terminals of the impedance Z ₂ . It then appears that the receiver R _v will be de-energized, confirming the new state of the circuit, and that the receiver R _c , will be able to be re-energized as soon as the last shunt axle of the train has crossed, in turn, the point P _l since then the transmitter E _{v will} inject the signaling current behind the train. We therefore have information corresponding to the detection of the passage of the last shunt axle of the train at a point P ₁ of the track circuit.

It will also be noted that with such an arrangement, the transmission of information between the track and the machine is never interrupted. In fact, when the transmitter Ev is switched, the receiver on board the train already receives the necessary information from the transmitter which equips the track circuit located downstream.

The release of the area constituted by the electrical joint J ₁ and the track portion "d ₁ " lying between the impedance Z ₁ and the point P ₁ makes it possible, as illustrated in the figure by the AM connection, to deliver information d operation towards the signaling equipment located upstream of the track circuit, authorizing for example an early opening of the upstream signals as soon as the rear axle of the train has crossed this point P ₁ , the distance "d ₁ " being considered as limit by example vis-à-vis the braking characteristics of trains running on the track. The return of the entire track circuit to the initial state will be triggered by the re-energization of the receiver Rv, this re-energization being obtained when the last shunt axle of the train is sufficiently far downstream of the impedance Z ₂ of the output joint J ₂ of the track circuit.

Referring now to Figure 2, we will describe an example of application of the invention to an operating problem related to a network in which the traffic density and, therefore, the limitation to a duration as low as possible, parking time from trains in front of a closed signal, is the dominant element. So a network comprising, in particular, two stations A and B. The entrance to station A is protected by an input signal Si, and its output, by an output signal S ₂ . Similarly, the entrance to station B is protected by an input signal S ₃ , while its exit is protected by a signal S ₄ .

The track circuits of the network portion considered are naturally equipped in accordance with the invention. Thus, in particular, the track circuit separating the output of station A (signal S ₂ ) from the input of station B (signal S ₃ ) comprises a sensor Ci at a point Pi, and the platform track circuit of station B has a Ce sensor at a point P _B.

In conventional operation, with a buffer section, the signal S ₁ can only be released when the inter-station block is fully released. Consequently, a train T _A can only access the platform of station A when the train preceding T _B has completely cleared the track circuit between the two signals S ₂ and S ₃ . The implementation of the track circuits according to the invention makes it possible, as soon as the last shunting axle of the train releases the portion of the track d between the output signal S ₂ and the point P _l of the location of the sensor Ci to prematurely unblock the signal S ₁ , authorizing the train T _A to access the platform of the downstream station (inter-station circuit). Similarly, the clearance by train T _B of the track portion between the input signal S ₃ of station B and point P _B , will allow train T _A to leave station A 'before clearance complete from station B platform by train T _B. All these operations are carried out automatically, thanks to an automatic switching control system CAC connected to the various elements of the network.

However, it appears that an arrangement such as that described in FIG. 1 can lead to a premature re-excitation of the receiver R _c , if the distance "d ₁ " is less than the interval existing between two contiguous axles of the train. The scheme block diagram of FIG. 3, which takes up all the elements of FIG. 1, represents an alternative embodiment of the invention allowing precisely to alleviate such a situation, thanks to the use of an additional sensor C ₂ implanted at a point P ₂ located upstream so that the distance "d ₂ " separating the sensor C ₂ from the sensor Ci is greater than the maximum length existing between two adjoining axles on the trains running on the network. With this sensor C ₂ are associated the sensitive receivers Rc ₂₂ and Rc ₂₁ , one at the frequency F ₂ of the upstream track circuit, the other at the frequency F _i of the track circuit. The early release information will then be delivered when all three receptors Rc ₁ , Rc ₂₁ , Rc _{22 are re-} energized.

Preferably, the sensor C ₂ is located in the middle of the joint J ₁ . It then makes it possible, with its associated receivers, to specify the position of the "fictitious joint" entering the track circuit delimited by the electrical joints J ₁ and J ₂ and to verify the release of the entire upstream joint J _i . Indeed, when the first shunt axle of the train enters the joint J _i , it begins by de-energizing the receiver Rc ₂₂ , then the receiver Rc _{21 as} soon as it has crossed point P ₂ , thus defining precisely the location of the fictitious seal marking the entrance to the track circuit in question.

For reasons of symmetry, a sensor C ₃ , associated with a receiver Rc ₃₁ sensitive to the frequency F ₁ and a receiver Rc ₃₂ sensitive to the frequency F ₂ is installed at point P ₃ of the joint J ₂ , allowing the return control of the COM switch in the initial state when the entire joint J ₂ has been released by the last shunt axle of the train.

Advantageously, the receivers Rc ₂₁ and Rc ₃₂ can replace the receivers of the concerned track circuits, normally connected to the terminals of the impedances Z ₁ and Z ₄ .

In the embodiment of the invention represented in FIG. 1, it has been seen that the switching between the transmitting and receiving members was only carried out when the first shunting axle of the train penetrated into the output joint. J ₂ , this in order not to interrupt the transmission of information between the track and the machine. However, it may be that at this instant, the last shunt axle of the train has already passed the point of installation P ₁ of the sensor Ci, either because it is a very short train, or again because the distance between the sensor and the downstream end of the track circuit is simply greater than the length of the train. The proper functioning of the system therefore requires a special installation of the sensor Ci as a function of the minimum length of the trains running on the track.

The variant embodiment of the invention shown in FIG. 4, which incorporates all the elements of FIG. 3, makes it possible precisely to remedy this drawback, thanks to the addition of an additional transmitting member E. The switching in accordance to the invention between the transmitting and receiving members then takes place firstly between the receiver Rv and the additional transmitter E, and this as soon as the receiver R _c , associated with the sensor Ci becomes de-energized, while the transmitter E _v remains connected to the terminals of the impedance Z ₂ and can thus continue to transmit information from the channel to the machine. It will also be noted that the additional transmitter E can consist in a simple manner of a device of known type making it possible to take a part of the energy available at the output of the transmitter Ev to inject it across the terminals of the impedance Z ₁ under the conditions determined by the state of the COM switch.

The state thus defined of the switching logic LOG and of the switch COM constitutes, for the information processing device TI, the memorization of the occupation of the track circuit although, due to the simultaneous presence of the two transmitters Ev and E, the receivers Rc ₂₂ , Rc ₂₁ , Rc ₁ , Rc ₃₁ , Rc ₃₂ can be excited at the same time as long as the length of the train occupying the track circuit is less than the distance d ₃ separating the point P _l d implantation of the sensor Ci of the downstream end of the track circuit constituted by the impedance Z ₂ .

This memorization will be canceled when the first axle of the train crossing the point of implantation of the impedance Z ₂ at the terminals of which the transmitter E _v is connected, the receiver Rc ₃₁ will be de-energized. In the second step, the switching logic LOG will then lead to the disconnection of the additional transmitter E and the connection in place of this transmitter (that is to say at the terminals of the impedance Zi) of the transmitter E _v , the presence of which is no longer necessary downstream of the track circuit since the head of the train has already crossed the corresponding end of the track circuit. This avoids the conflict between the signals of the two transmitters E and E _v during the release by the last axle of the train of the interval Z ₁ ―Z ₂ while preserving the permanence of the information of presence of the last axle of the train upstream of the point P _t which, as we have seen, requires the presence of a transmitter at the upstream end of the track circuit.

The return of the device to the initial state will be triggered by the re-excitation of the receiver Rc ₃ , which will take place when the last axle of the train has passed point P ₃ , thus releasing the track circuit.

The block diagram of FIG. 5 represents another variant embodiment of the invention in which several successive sensors such as Ci, C ₄ , C _{5 are used} , distributed along the track circuit considered, each of these sensors being associated with a receiver sensitive to the frequency Fi, respectively Rc ,, Rc ₄ and Rcs. In this alternative embodiment which naturally incorporates all the elements of FIG. 4 with the corresponding operating mode, the transmitter E _v is connected successively over time and immediately downstream of the various sensors, ie at points 1, 2, 3, then at the terminals of the impedance Z ₂ , as the train progresses in the block. It obviously follows that the receptors associated with each of these sensors are successively de-energized as the first shunt axle of the train is inserted between the transmitter E _v and the sensor concerned.

Such an arrangement makes it possible in particular to simultaneously detect the presence of the first axle and of the last axle of the train inside the track circuit, and therefore to locate the train geographically on this track circuit. This arrangement also makes it possible, in particular in the case of long track circuits, to improve if necessary the conditions for transmitting information from the track to the machine by reducing the length of the track existing between the transmitter E _v which generates the information to be transmitted to the head of the train which receives this information.

Claims (5)

1. A railway track circuit formed by the two rails (r_i, r₂) of a railway track portion and comprising a transmission member (Ev) connected to the downstream end (Z₂) of the circuit and a reception member (R_v) connected to the upstream end (Z_i), characterized in that it further comprises at least one electromagnetic sensor (C_I) disposed at a given position along the track circuit, a receiver (R_c,) associated with the sensor and switching means (COM) for switching the transmission (E_v) and reception (R_v) members of the track circuit, after the receiver (R_c,) associated with the sensor (C_i) has been deenergized by the passage over said sensor of the first shunt axle of the train travelling over the track.

2. A track circuit according to claim 1, of the type with electric separation joints (J₁, J₂), characterized in that it comprises a second sensor (C₂) disposed upstream of the first one and beyond the corresponding end (Z_i) of the track circuit, at a distance (d₂) therefrom greater than the maximum gap existing between two contiguous shunt axles of the trains likely to travel over the track, this sensor (C₂) being associated with a receiver (Rc₂₁) sensitive to the operating frequency (F_l) of the track circuit considered.

3. A track circuit according to claim 2, characterized in that the second sensor (C₂) is implanted in the median zone of the electric separation joint (J_i) and it is associated with a second receiver (Rc₂₂) sensitive to the operating frequency (F₂) of the track circuit situated upstream.

4. A track circuit according to any one of claims 1 to 3, characterized in that the track circuit comprises an additional transmission member (E) which is connected in place of the reception member (R_v) as soon as the receiver (R_c,) associated with the sensor (C₁) is deenergized, whereas the original transmission member (Ev) remains connected to the downstream end (Z₂) of the track circuit.

5. A track circuit according to claim 4, characterized in that several electromagnetic sensors (C₁, C₄, C₅), each associated with a receiver (Rc₁, Rc₄, Rc₅), are spaced apart along the track circuit, the original transmission member (E_v) being connected successively in line, immediately downstream of the different sensors, then to the downstream end (Z₂) of the track circuit, as the train advances into said track circuit.

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