CONTACT STRIP OF A POWER CONSUMER AND CORRESPONDING RAIL VEHICLE AND MONITORING METHOD

Description

Technical field of the invention

[0001] The invention relates to the field of electrical engineering for railway applications and, more particularly, to pantographs. More specifically, it relates to a friction strip for pantographs, used to transfer electrical energy between a fixed power distribution means, such as a catenary, and a mobile electrical power-consuming device, such as a train, metro, or tram traction unit, which is equipped with such a friction strip. This friction strip includes a wear detection device. State of the art

[0002] For a railway vehicle equipped with an electric traction motor, pantographs provide electrical contact between the traction unit (e.g., the locomotive) and the overhead contact line (catenary). More specifically, the pantograph includes a friction element that makes mechanical contact with the catenary. The friction element is a strip positioned horizontally and approximately perpendicular to the catenary. This element, also called the "friction strip," comprises a wear strip attached to a bracket. The wear strip is an electrical conductor that collects and transmits the electrical current from the catenary to the pantograph to power the electric traction system, via the bracket, a metal support that serves as a base for the wear strip.

[0003] To ensure stable electrical contact, the pantograph exerts a pressure force against the catenary. This force is not constant but can depend, on the one hand, on the development of the pantograph (which depends on the height of the catenary relative to the railway track), and, on the other hand, on aerodynamic effects, the latter being a function of the development of the pantograph, the forward speed of the railway vehicle, and the speed and direction of the wind.

[0004] The wear strip is made of a less hard, electrically conductive material than the catenary wire, to prevent premature wear of the catenary; this material is typically a high-carbon compound. Therefore, it is the wear strip that experiences the most wear: the friction strip is a consumable part that must be replaced regularly, as it is not normally intended to replace only the wear strip. If the wear strip breaks, the electrical contact between the catenary and the pantograph can be interrupted: this disrupts the train's power supply, potentially causing the train to stop in rural areas. A broken wear strip can also lead to the pantograph rising uncontrollably, continuing to exert force against the catenary as the train moves: thus, a broken wear strip can cause the catenary to be damaged by the pantograph or the pantograph head to be torn off.This represents a major incident requiring the intervention of a team of technicians on site, with interruption of rail traffic for several hours, or even several days.

[0005] The wear of the tread is not simply a function of the number of kilometers traveled by the train: wear depends on the pressure force exerted by the tread against the overhead line, the train's speed, the wind speed and direction, weather conditions (rain, snow, frost, temperature), and electrical arcs that can occur during friction between the tread and the overhead line. Furthermore, excessive temperature not only accelerates tread wear but also promotes separation of the transition zone between the tread and its metallic substrate (stirrup).

[0006] Systems exist that detect wear on the contact strip, allowing for its replacement before it breaks. Typically, this detection must occur early enough to allow the train to reach its destination station, where the maintenance crew can then replace the contact strip. Even if this objective is not met, it would still be desirable for the detection system to prevent the pantograph from rising in the event of a contact strip failure, thus avoiding damage to the overhead contact line. These detection systems are of various types.

[0007] Numerous documents describe systems in which the friction strip includes a sealed longitudinal enclosure containing a fluid, such that if wear exceeds a certain value, or if the wear strip ruptures, the enclosure loses its seal, resulting in leakage or a change in the fluid's pressure. This event can be detected to trigger the retraction of the pantograph. In English patents GB 1,374,972 and GB 2,107,662 (Morganite Carbon), the enclosure is a tube made of plastic or rubber material capable of withstanding operating temperatures up to 80°C. In French patent FR 2,663,592 (Le Carbone Lorraine), the enclosure is a tube made of carbonaceous material with the same mechanical characteristics as the wear strip.In US 5,189,903 (Hoffmann & Co), EP 0 402 666 A1 (Ringsdorff-Werke), and EP 0 384 972 A2 (Schunk Bahntechnik), the enclosure is formed at least in part by the walls of a groove cut into the lower part of the friction strip. EP 0 872 374 A1 (Le Carbone-Lorraine) proposes using a sealed aluminum or copper tube with a hardness of less than 4 on the Mohs scale. Another device using a notched brass tube is described in WO 2014 / 102508 (Mersen France Amiens).

[0008] These devices have some drawbacks. They must be connected to a fluid circuit, such as compressed air, which increases both the weight of the device and its maintenance. They only allow for a single level of detection (container integrity or fluid leak), which means that predictive maintenance can only be performed once the wear threshold of the friction strip that triggers fluid loss has actually been reached.

[0009] The main drawback of these automatic emergency lowering systems (known as ADD = Automatic Drop Device) which implement pneumatic detection associated with an automatic retraction system is that they cause an automatic lowering of the pantograph arm in order to avoid significant damage to rolling stock and / or infrastructure; this disrupts the power supply to the railway vehicle and impacts the availability of the train.

[0010] EP 0 525 595 A1 (Siemens AG) describes a wear strip in which optical fibers have been embedded at different depths. As the thickness of the wear strip decreases due to wear, the optical fibers are damaged. Optically, one can thus deduce as many wear levels of the wear strip as there are optical fibers at different depths. This gives some indication of the remaining thickness of the wear strip, but this solution is technically quite complex, both for the manufacture of the wear strip and for the optical detection system. WO 2006 / 065 985 (Pantrac GmbH) proposes drilling blind holes in the lower part of the wear strip; the wear of these holes can be measured by an optical fiber embedded in the hole.Using holes of different depths can detect multiple levels of wear, but this optical device is complex and only allows monitoring in discrete areas of the strip.

[0011] We should also mention WO 2005 / 044614, which describes the use of fibers in the contact strip bracket to determine the pressure exerted by the catenary on the pantograph head. This device is coupled with geolocation to provide a representative image of the network's condition, particularly the catenary tension setting. However, this solution is not economically viable, making its use in commercial service problematic. Finally, JPH08107603 (A) describes a very rudimentary solution in which the pantograph is given a specific shape to allow observation of the strip's wear level. This system does not allow monitoring of the strip in dynamic mode, i.e., during normal vehicle operation. In practice, the teachings in these last two documents therefore do not address the problems presented above.Another pantograph with detection of the wear state of the friction strip by an electric wire is known DE8803377U1.

[0012] Generally speaking, the pantograph of a railway traction unit, and especially in the case of a high-speed train, represents a highly disrupted environment in terms of mechanical factors (speed, wind, vibration, frost), thermal factors (summer and winter temperatures, increased temperature due to friction), electrical factors (high voltage, high current, electric arcs, humidity, snow), and electronic factors (electromagnetic fields, rotating electrical machines, transformers, circuit breakers). It is therefore not a suitable environment for installing precision metrological devices. Furthermore, it is not an environment easily accessible for maintenance. Under these conditions, any human intervention on the pantograph must follow rigorous procedures to avoid endangering personnel. Consequently, adherence to these procedures increases the duration of the intervention.

[0013] In view of the foregoing, one objective of the present invention is to remedy, at least partially, the disadvantages of the prior art mentioned above.

[0014] Another objective of the invention is to provide a friction strip whose degree of wear can be monitored continuously and in real time without impacting the availability of the equipment.

[0015] Another objective of the invention is to offer such a friction strip which has a manufacturing cost comparable to that of state-of-the-art solutions, while providing new functionalities.

[0016] Another objective of the invention is to provide such a friction strip which can be easily installed on existing pantographs, as well as on new pantographs.

[0017] Another objective of the invention is to propose such a friction strip which is accompanied by a low impact, in terms of mass and aerodynamic drag at the head of the pantograph. Objects of the invention

[0018] According to the invention, at least one of the above objectives is achieved by means of a friction strip for a pantograph of a vehicle, in particular a railway vehicle, said friction strip comprising means for fixing to said pantograph, in particular a bracket, as well as a wear strip intended to come into contact with a catenary, this wear strip being made of a first electrically conductive material, said friction strip further comprising a conduit, called a pneumatic sensing conduit, adapted to contain a fluid under pressure, and connecting means for linking this pneumatic sensing conduit to a pneumatic sensing circuit, characterized in that said friction strip further comprises at least one electrically conductive element, called an electrical detection element, made of a second electrically conductive material whose electrical conductivity is greater than that of said first electrically conductive material, this electrically conductive element being interposed between said conduit and the upper surface of the wear strip, means for connecting said electrically conductive element to an electrical detection circuit, integrating said electrically conductive element.

[0019] Other embodiments of the friction strip according to the invention may further include the following features: a) The upper surface of said electrically conductive element is located at a predetermined depth relative to the upper surface of said wear strip in its unworn state, this depth being in particular approximately 20 millimeters. b) In the unworn state of said wear strip, the difference between the depth of the upper surface of said electrically conductive element and the depth of the upper surface of said conduit is approximately 5 millimeters. c) Said electrically conductive element is elongated and extends transversely within the wear strip, with reference to the direction of travel of the vehicle, said electrically conductive element and said conduit preferably being mutually parallel. d) The strip further comprises electrical insulation means for isolating said electrically conductive element from the wear strip.e / said at least one electrically conductive element is fixed, in particular by bonding, against the bottom of a groove in the wear strip. f / the support defines a cavity open at the top, and an insert is further provided, housed in a groove in the wear strip, said insert closing the opening of said cavity so as to form said conduit. g / said insert holds said at least one electrically conductive element in position against the bottom of said groove. h / the electrical insulation means comprise an insulating sheath of said electrically conductive element and / or said insert, said insert being made of an electrically insulating material, in particular silicone. i / the connection means are removable connection means, suitable for being removably connected to a connecting cable of said electrical detection circuit.j / The removable connection means comprise two electrical connectors, provided at the two opposite longitudinal ends of said electrically conductive element. k / The removable connection means comprise a single electrical connector, said electrically conductive element forming a loop whose two ends cooperate with said single electrical connector. l / The strip comprises at least two electrically conductive elements, a first electrically conductive element being oriented towards the catenary during normal vehicle operation so as to provide a first level of warning, while at least one other electrically conductive element is interposed between said first electrically conductive element and said conduit, so as to provide at least another level of warning.

[0020] These additional features a / to l / can be implemented with the main object above, individually or in any technically compatible combinations.

[0021] The invention also relates to a railway vehicle comprising a body and a pantograph, said pantograph having a frame mounted on said body of said vehicle, a friction strip intended to come into contact with a catenary and means of connection between the frame and the friction strip, characterized in that the friction strip is as defined above, and the vehicle further comprises a pneumatic detection circuit incorporating said detection conduit, as well as identification means, suitable for identifying a pressure variation in said pneumatic circuit, at least one electrical detection circuit incorporating said at least one electrically conductive element, as well as detection means, suitable for detecting the variation of a parameter representative of said detection circuit, such as the electrical interruption of said detection circuit.

[0022] According to other additional characteristics of the railway vehicle conforming to the invention: a) This vehicle includes warning means capable of being activated when said variation falls outside a predetermined response range, particularly in the event of an electrical failure of said detection circuit. b) This vehicle further includes a control / command module integrating the detection and warning means, this module being capable of cooperating with said electrical detection circuit. c) Said control / command module includes wireless communication means suitable for transmitting information to said railway vehicle and / or the ground. d) Said control / command module is fixed, including in a removable manner, to the pantograph head.

[0023] These additional characteristics a' / to d' / can be implemented with the second object above, individually or in any technically compatible combinations.

[0024] The invention also relates to a method for monitoring the wear of a friction strip as defined above, mounted on a vehicle as defined above, in which: we detect the variation of a parameter representative of said electrical detection circuit, such as the electrical break of said detection circuit; we deduce from this the contact of the electrically conductive element (5) with the catenary.

[0025] Furthermore, the said process includes a step in which a first characteristic time (t1) is determined, corresponding to the contact of the electrically conductive element with the catenary, a second characteristic time (t2) is estimated, corresponding to the contact of the conduit with the catenary, and a so-called safety service time is estimated, corresponding to the difference (t2-t1) between the second characteristic time and the first characteristic time.

[0026] The invention ultimately relates to a method for improving (or "upgrading") a railway vehicle comprising a body and a pantograph, said pantograph comprising a chassis mounted on said vehicle body, at least one friction strip, called the original strip, intended to come into contact with a catenary and means of connection between the chassis and the friction strip, said friction strip comprising means of attachment to said pantograph, in particular a bracket, as well as a wear strip intended to come into contact with a catenary, this wear strip being made of a first electrically conductive material, said friction strip further comprising a conduit, called the pneumatic detection conduit, adapted to contain a fluid under pressure, and means of connection suitable for linking this pneumatic detection conduit to a pneumatic detection circuit, characterized in that said at least one original friction strip is replaced by a friction strip conforming to any one of the preceding claims, said replacement friction strip; said vehicle is equipped with at least one electrical detection circuit and with detection means, suitable for detecting the variation of a parameter representative of said detection circuit, such as the electrical interruption of said detection circuit; said at least one electrically conductive element of said replacement friction strip is connected with said electrical detection circuit. Figures

[0027] There figure 1 is a schematic profile view, illustrating a railway vehicle capable of using a friction strip according to the invention. figure 2 is a larger-scale profile view, illustrating a pantograph of the railway vehicle of the figure 1which is equipped with two friction strips according to the invention. The figure 3 is a cross-sectional view, schematically illustrating a friction strip according to the invention. figure 4 is a longitudinal cross-sectional view, schematically illustrating the friction strip of the figure 3 . There figure 5 illustrates on a larger scale detail V of the figure 2 . There figure 6 is a longitudinal cross-sectional view, analogous to the figure 4 , schematically illustrating a friction strip conforming to a variant embodiment of the invention.

[0028] The following numerical references are used in the figures: 300 Vehicle 1,1' Rubbing strip 302 Railway line 3 Wear strip 304 Catenary H3 Initial height of 3 306 Vehicle roof 300 308 Pantograph 202 Pantograph chassis 308 5 Conductive element 204 202 chassis frame 2 Support 206 Electrical insulators 71,72 Connectors 208 Bow 21,22 2-inch edges 210 Articulated arm 23 Cavity of 2 214 Main lower stem W Wear zone of 3 216 Main upper stem 30 Top surface of 3 218 Auxiliary lower stem 31 Throat of 3 222 Reminder device 32 Adhesive 224 Deployment device 33 Insert 4 Conduit 41,42 Ends of 4 43,44 4mm nozzles 40 Top surface of 4 H4 Altitude of 4 45 Pneumatic circuit 46 Pneumatic controller 50 Top surface of 5 H5 Height of 5 20 Sheath 8,8' Detection circuits 81,81' Connection cabling 9 Control / command module 91 Means of detecting 9 92 Alert methods of 9 93 Wireless communication L3 Width of 3 L33 Width of 33 101 Friction strip ( figure 6 ) 105 Driver ( figure 6 ) 151 End of 105 152 End of 105 171 Single connector 120 single sheath 309 Pantograph head Description

[0029] In this description, the terms "conductor" and "insulator" refer to electrical conduction, unless otherwise stated.

[0030] With reference to the figure 1 a railway vehicle 300 The implementation of the invention will now be described. The railway vehicle 300 is designed to run on a railway track 302 above which extends a catenary 304 through which an electric power supply current passes. The railway vehicle 300 includes a roof 306 on which a pantograph is fixed 308 designed to capture, in a manner known per se, the electrical current supplying the catenary 304 and thus provide electrical power to the railway vehicle 300.

[0031] With particular reference to the figure 2 the pantograph 308 will now be described in more detail. The pantograph 308 includes a chassis 202 fixed to the roof 306 of the railway vehicle. In the example described, the chassis 202 includes a frame 204 and electrical insulators 206 connecting the frame 204 on the roof of the railway vehicle. The pantograph 308 It also includes a bow 208 intended to be in contact with the catenary 304 in order to capture the power supply current.

[0032] The catenary is located vertically at a distance from the chassis 202 which can vary considerably. To compensate for variations in the distance between the catenary and the chassis 202, the pantograph also includes an articulated arm 210 connecting the bow 208 to the chassis 202, so that the bow 208 is located at a variable distance from the chassis 202.The articulated arm 210 is designed to expand vertically in order to move the bow 208 in relation to the chassis 202 in order to maintain the bow 208 in contact with the catenary. Thus, the articulated arm 210 is designed, on the one hand, to expand vertically in order to move the bow away 208 of the chassis 202 when the distance between the catenary 304 and the chassis 202 increases and, on the other hand, folds vertically in order to bring the bow closer 208 of the chassis 202 when the distance between the catenary 304 and the chassis 202 decreases.

[0033] In the example described, the articulated arm 210 is in two parts and includes a main lower stem 214, mounted transversely pivoting on the chassis 202, for example on the frame 204,presenting an angle A1 with the longitudinal direction, as well as a main upper rod 216 mounted transversely pivoting on the main lower rod 214 and presenting an angle A2 with the longitudinal direction. The bow 208 is mounted transversely pivoting on the main upper rod 216.

[0034] The articulated arm 210 it also includes, in a known manner, an auxiliary lower stem 218 mounted transversely pivoting on the chassis 202 (for example, on the frame 204) and on the main upper stem 216, in order to control the angle A2 of the main upper rod 216 at angle A1 of the main lower stem 214, so that increasing angle A1 results in increasing angle A2.

[0035] The articulated arm 210It also includes, in a known manner, an auxiliary upper rod (not shown), mounted transversely and pivotally on the main lower rod. 214 and on the bow 208, so that the bow maintains a substantially constant angle with the longitudinal direction L regardless of the development of the articulated arm 210.

[0036] The pantograph 308 It also includes a recall device 222 designed to encourage the articulated arm 210 to develop. Thus, the bow 208 is kept in contact with the catenary 304. The recall device 222 It includes, for example, an air cushion, a spring, or an electric motor. Furthermore, the pantograph 308 includes a deployment device 224 allowing the pantograph to be deployed or removed according to the service requirements of the railway vehicle.

[0037] The bow 208shown on the figure 2 is a so-called double bow, insofar as it has two friction strips conforming to the invention at its apex. 1 And 1'. These friction strips, which will be described in more detail below, are in mechanical contact by rubbing with the catenary. 304 when the pantograph 308 is deployed; they thus ensure a dynamic electrical contact between the catenary 304 and the pantograph 308.

[0038] The present invention relates more particularly to each friction strip 1 and 1' mounted on the bow. The structure of the first friction strip 1 in accordance with the invention will now be explained in great detail in relation to the figures 3 to 5 , it being understood that the structure of the other band 1' is identical.

[0039] In a way that is well known in itself, the friction strip 1first of all, it includes a metal support 2, also called a "bracket," which forms a mounting base. Typically, this bracket is an extruded profile made of aluminum or aluminum alloy. In a way that is well known in itself, the support 2 is equipped with two longitudinal edges 21 And 22, visible in particular by figure 3 These edges define a cavity 23, roughly U-shaped, which is open at the top.

[0040] On this stirrup 2 a wear strip is attached 3 made from a first material that is electrically conductive and softer than the catenary wire 304. Typically, the friction strip 3 is made of carbon material. It constitutes the active zone for the transfer of electrical energy from the catenary 304 towards the bow and the pantograph. Typically, this wear strip can be inserted longitudinally inside the stirrup.2. This wear strip 3 presents a central area W of a substantially constant thickness, which represents its main wear zone. The initial height of the upper surface 30 of this wear strip 3 is identified by the line H3 of the figure 3 .

[0041] This wear strip 3 is carved with a gorge 31, which opens onto the lower surface of this strip 3. As we will see in more detail below, this groove allows for the reception of an elongated conductive element 5, which is fixed against the upper wall of the throat by means of a layer 32 with a suitable adhesive. This groove also allows for the reception of an insert 33, said retaining insert, the lower face of which ensures the closure of the cavity 23. In this way, this lower face, together with the walls of this cavity, defines a conduit 4including its two longitudinal ends 41 And 42 are connected to their respective connection nozzles 43 And 44. The upper surface 40 of the conduit 4 is advantageously situated at a constant altitude noted H4, visible on the figure 3 .

[0042] These nozzles are known to be of a certain nature. 43 And 44 are connected to a pneumatic circuit 45, visible on the figure 2 This circuit contains a fluid, typically compressed air. It is connected to a pneumatic controller. 46, in order to control the device 224 described above, ensuring the deployment of the pantograph. In case of wear beyond a certain value, or in case of breakage of the wear strip 3, There is a loss of seal at the pipe level 4,resulting in leakage or a change in the pressure of the fluid. This occurrence is detected by the controller. 46, which activates the device 224 in order to trigger the retraction of the pantograph. Conduit 4 and the fluid circuit 45 They belong to an automatic emergency lowering system, known as ADD, or "Automatic Drop Device". The various functions related to this ADD system are well known and will not be described in further detail.

[0043] According to the invention, the wear strip 3 includes, in addition to the conduit 4, the elongated conducting element 5 mentioned above. As shown by the figure 4 the conduit 4 and the element 5extend in a substantially parallel manner, meaning that their difference in height is substantially constant. This conductive element is made of a second electrically conductive material, the electrical conductivity of which must be greater than that of the first electrically conductive material. This conductive element can be a copper wire. Its upper surface 50 is advantageously situated at a constant altitude, denoted H5.

[0044] This longitudinal conducting element 5 must be electrically isolated from the wear strip 3 and in relation to the metal support (bracket) 2. In the present embodiment, this conductive element 5, which is covered with an insulating layer (not shown), is embedded in the insert 33.The latter is made of an electrically insulating material, for example silicone. Consequently, this insert contributes, in addition to the aforementioned casing, to the insulation function between the longitudinal conductive element 5 and the wear strip 3. This insert provides an additional retaining function, making it easier to handle when closing the duct. 4 and the installation of the longitudinal conductive element 5.

[0045] Said longitudinal conducting element 5 is connected at each of its ends 51 And 52 to a respective connector 71, 72. In order to ensure electrical insulation between said longitudinal conductor element 5 and the metal support 2 A protective sheath is planned near each end of the connector. 20 insulating layer that separates the longitudinal conducting element 5vis-à-vis the metal support 2. Each connector allows the element to be connected 5 to a so-called connecting cable 81, extending between these connectors, visible in particular in figure 5 This element 5 shape, with the two connectors 71, 72 and the wiring 81, a so-called detection circuit, designated as a whole by the reference 8. The connection between the two ends of the wiring 81 and the connectors 71 And 72, illustrated on the figure 4 , is advantageously of the removable type.

[0046] A control / command module 9 is located in the vicinity of both the connecting cabling 81 of the first detection circuit 8, but also connecting cabling 81' of the second detection circuit associated with the second band 1' (see figure 5 As this figure shows, this module 9 is fixed to the head309 of the pantograph 308, by any appropriate means. This module 9 allows not only the detection of a malfunction at the level of each circuit 8 Or 8', but also to provide information relating to this malfunction to the railway vehicle and / or the ground.

[0047] For this purpose, this module 9 is first of all equipped with detection devices 91, of a type known in itself, which allow the identification of a variation in a circuit operating parameter 8 Or 8', That is to say, a power outage at that point. Furthermore, this module is equipped with alert systems. 92, enabling the provision of detailed information to the rail vehicle and / or the ground. These warning systems are advantageously wireless, as evidenced by the reference 93. These alert systems 92,These are of a classic nature, for example, of the binary type (1=closed circuit, 0=open circuit). As soon as the wear of the wear strip reaches the conductor 5, This conductor is cut by friction with the catenary and opens, thus changing the electrical resistance of the circuit.

[0048] The following numerical values ​​are given below, without limitation: conductor diameter 5 : between 1.0 mm (millimeter) and 1.5 mm; difference in altitude between the upper surface 30 of the band 3, in its unworn state, and the upper surface 50 of the driver 5 typically on the order of 20 mm. This difference in altitude, shown on the figure 3 , is called depth P5 of the driver; difference in altitude between the upper surface 30 of the band 3, in its unworn state, and the upper surface 40 of the conduit 4,at the level of the inner face of this duct: typically on the order of 25 mm. This difference in height, shown on the figure 3 , is called depth P4 of conduit 4. difference in depth (P5-P4) between the respective depths of the conductor 5 and the conduit 4 typically around 5 mm.

[0049] The frictional contact between the catenary 304 and the upper surface 30 of the wear strip 3 is done in different locations distributed across the main wear zone W, because of the catenary centering 304 relative to the railway track is not constant. Therefore, the wear in the main wear zone W is fairly uniform. As the catenary makes contact by rubbing with the upper surface 30 of the wear strip 3,The latter is subject to wear. Consequently, the altitude of this upper surface decreases, as does the distance δ between this upper surface 30 and the upper surface 50 of the longitudinal element 5. For example, when the surface 30 will be at the height H3', illustrated in mixed lines on the figure 3 , the distance between the upper surface H3 of the band and the upper surface of the longitudinal element 5 will have decreased by δ has δ'.

[0050] When the height of the wear strip 3 decreases until it reaches the level of the upper surface of the insulating insert 33, electrical contact between friction strip 1 and catenary 304 is not interrupted because the width L33 The width of this insulating insert is small compared to the width L3 of the wear strip 3 (see figure 3). The friction strip 1 can therefore continue to perform its function as a current collector between the catenary and the vehicle 300 while the wear strip 3 progresses towards the base of the insulating insert 33.

[0051] When the thickness of this insulating insert 33 was removed by friction with the catenary; the catenary then wears down the longitudinal conductive element 5 and the longitudinal conducting element 5 will eventually be severed. According to the invention, it is preferable to detect the severance of the longitudinal conductive element 5 by monitoring the electrical resistance of the circuit. As long as the conductor 5 If the conductor is not broken, the circuit resistance read by the module is low, typically less than 1 Ω. As soon as the conductor 5 is cut, this resistance will become very high, typically greater than 1 MΩ.

[0052] We now describe a manufacturing process for a friction strip 1 according to the invention. The metal support (bracket) is supplied 2, the longitudinal conducting element 5, the wear strip 3, protective sheaths 20, as well as the insert 33. We are preparing the throat 31 in the wear strip 3 to accommodate this electrically insulating material. In this way, this material first allows the conduit to be sealed. 4 in the upper part of the cavity 23 support 2, while mechanically restraining the driver 5 compared to the wear strip 3.

[0053] The electrically insulating material from which the insert is made 33, is typically made using silicone extrusion. The longitudinal ends of the cavity are known in this way. 23 metal support 2are sealed to prevent leaks from the pneumatic circuit. Then the lower part of the wear strip is fixed. 3 in the profile 2 Once properly pre-formed, the insulating protective sheaths are installed. 20 and the ends of said longitudinal conducting element are brought out 5 through said sheaths 20.

[0054] According to the invention, the wear of the friction strip 1 is detected as follows. When a new friction strip is installed, it is recognized by the module, which resets the timer. Then, when the conductive element 5 Or 5' is cut / worn by the catenary, the module 9 then detects an abnormal response from the circuit 8 Or 8'whose resistance becomes very high, even infinite. This initial information is then transmitted towards the railway vehicle and / or the ground. Furthermore, the occurrence of this event is affected by a first characteristic time t1.

[0055] The module 9 It can then calculate the average wear rate of the worn strip and thus, by extrapolation, generate a predictive analysis of the wear of the new strip. It can also calculate a second characteristic time t2, corresponding to the contact point between the catenary and the conduit. 4. This value t2 is approximately equal to: t2 = (P4 / P5) * t1, assuming that the wear rate is constant. The module then estimates a duration called the safety time (t2-t1), which corresponds to the remaining service life before the belt 3 does not wear down to the conduit 4and, consequently, does not trigger the opening of the pneumatic circuit and the loss of availability of the pantograph.

[0056] The module 9 This information is transmitted to the operator, who can then plan the maintenance operation optimally. The operator can take all necessary precautions to avoid triggering the pneumatic circuit. Indeed, as mentioned above, this triggering necessarily results in the retraction of the pantograph arm, which therefore impacts the availability of the rail vehicle.

[0057] Finally, the autonomous module 9 is capable of regularly sending a message to the train and / or ground confirming its proper functioning. Any malfunction of the monitoring system, and in particular of this module 9, will therefore be automatically detected and communicated to the relevant personnel.

[0058] According to an embodiment of the invention not shown, at least two longitudinal conducting elements can be used, located at different depths. In this case, the upper electrically conducting element, that is, the one facing the upper surface 30, allows for the delivery of a first level of alert. Furthermore, the invention then provides for at least one other electrically conductive element, called an intermediate element, interposed between the conduit 4 and the upper electrically conductive element. This provides at least one additional level of alert, which is added to the level of alert provided by the first electrically conductive element. In this case, each electrically conductive element is equipped with its own connectors for connection to a respective detection circuit.

[0059] There figure 6illustrates a variant of the friction strip, according to the invention. In this figure 7, the mechanical elements are analogous to those of the figures 3 to 5 They are assigned the same reference numbers, increased by 100. The friction strip 101 of this figure 7 differs essentially from that 1 of the figures 3 to 5 , in that it comprises a single connector 171. Furthermore, the conductive element 105 forms a loop, so that its two ends 151 And 152 are adjacent and cooperate with the single connector 171 aforementioned.

[0060] This method of implementation of the figure 6 It offers specific advantages, particularly of an economic nature. Indeed, it reduces the number of components, since it uses a single connector. 171 and, consequently, to a single sheath 120.

[0061] The invention has many advantages.

[0062] The invention provides for the use of an electrically conductive element with which the catenary wire interferes before coming into contact with the pneumatic detection conduit. The invention thus makes it possible to significantly avoid the emergency lowering of the pantograph arm. Indeed, the operator is warned, thanks to this conductive element, of an "intermediate" wear state of the friction strip. Under these conditions, the operator can take all necessary precautions to avoid such an emergency lowering. Furthermore, the invention provides an alert level that is not only precise but also advantageously adjustable, thanks to the positioning of this conductive element. In particular, the invention makes it possible to estimate the remaining time before the automatic emergency lowering system (ADD) is triggered.

[0063] The invention is also economically advantageous. Indeed, the friction strip of the invention, being a consumable component, has a cost price comparable to that of a conventional strip. Furthermore, the monitoring system equipping a railway vehicle according to the invention involves a small number of mechanical components. This friction strip and this railway vehicle, both conforming to the invention, therefore have structures close to the prior art, while allowing for additional functionalities. This solution thus improves the availability of the pantograph and the service life of the wear strip, without compromising safety, which is still ensured by the conventional ADD system.

[0064] In this regard, it should be noted that it is particularly convenient to equip railway vehicles already in service with the friction strip according to the invention. It should be recalled that a conventional friction strip is equipped only with a conduit, intended to be connected to the pneumatic detection circuit. With reference in particular to the figure 5 It is now assumed that this conventional strip must be replaced by a strip 1 conforming to the invention. This strip is then placed 1 to the location originally occupied by the conventional band, then the conduit is connected 4 to the existing pneumatic circuit. Then the electrical detection circuit is installed. 8, that is connected to the connectors 71 And 72, as well as the module 9 control / command.

[0065] Using a control module capable of transmitting information wirelessly offers specific advantages. It eliminates the need for a wired connection between this module and the railway vehicle's electronics. This solution can be compared, firstly, to a connection using a conductor wire, which would be incompatible with the potential difference. Secondly, it can be compared to a fiber optic connection, which is relatively expensive and difficult to implement.

[0066] Finally, the invention allows monitoring of the entire width of the wear band. Indeed, it does not rely on discrete sensors located at specific points on this wear band.

[0067] The present invention is not limited to the embodiment described above, but is instead defined by the following claims. It will be apparent to those skilled in the art that modifications can be made to it. For example, the pneumatic circulation conduit can be made in the form of a tube embedded in the insert. However, the embodiment of the figures 3 to 5 is preferred, in particular because it is more economical.

[0068] Furthermore, the terms used in the claims should not be understood as limited to the elements of the embodiment described above, but should instead be understood as covering all equivalent elements that a person skilled in the art can deduce from their general knowledge.

Claims

1. Contact strip (1) for a pantograph (308) of a vehicle (300), in particular of a railway vehicle, said contact strip comprising means for fixing to said pantograph, in particular a bracket (2), as well as a wear strip (3) intended to come into contact with a catenary (304), said wear strip being made of a first electrically conductive material, said contact strip further comprising a conduit (4), called a pneumatic detection conduit, adapted to contain a fluid under pressure, and connecting means (43, 44) suitable for connecting this pneumatic detection conduit to a pneumatic detection circuit (45), characterized in that said contact strip (1) further comprises - at least one electrically conductive element (5), called an electrical detection element, made of a second electrically conductive material whose electrical conductivity is greater than that of said first electrically conductive material, this electrically conductive element (5) being interposed between said conduit and the upper surface (30) of the wear strip (3), - means of connecting (71, 72) said electrically conductive element (5) to an electrical detection circuit (8), incorporating said electrically conductive element.

2. Contact strip according to claim 1, characterized in that the upper surface (50) of said electrically conductive element (5) is located at a predetermined depth (P5) relative to the upper surface (30) of said wear strip (3) in the unworn state of the latter, this depth being in particular close to 20 millimeters, and in that in the unworn state of said wear strip (3), the difference between the depth (P5) of the upper surface (50) of said electrically conductive element (5) and the depth (P4) of the upper surface (40) of said conduit (4) is close to 5 millimeters.

3. Contact strip according to any one of the preceding claims, characterized in that said electrically conductive element is elongated and extends transversely inside the wear strip, with reference to the direction of travel of the vehicle, said electrically conductive element and said conduit preferably being mutually parallel.

4. Contact strip according to any one of claims 1 to 3, characterized in that it further comprises means (33) for electrical insulation, enabling said electrically conductive element (5) to be isolated from the wear strip (3).

5. Contact strip according to any one of the preceding claims, characterized in that said at least one electrically conductive element is fixed, in particular by bonding, against the bottom of a groove in the wear strip.

6. Contact strip according to any one of the preceding claims, characterized in that the bracket delimits a cavity open upwards, and there is further provided an insert, housed in a groove of the wear strip, said insert closing the opening of said cavity so as to form said conduit, and optionnally said insert holds advantageously said at least one electrically conductive element in position against the bottom of said groove, and / or said insert is advantageously made of an electrically insulating material, in particular silicone, and / or said contact strip comprises the features of claim 4 and said electrical insulation means comprise a sheath insulating said electrically conductive element.

7. Contact strip according to any one of the preceding claims, characterized in that the connection means are removable connection means, capable of being removably connected to a linking cable (81) of said electrical detection circuit (8).

8. Contact strip according to the preceding claim, characterized in that the removable connection means comprise two electrical connectors, provided at the two opposite longitudinal ends of said electrically conductive element.

9. Contact strip according to claim 7, characterized in that the removable connection means comprise a single electrical connector, said electrically conductive element forming a loop whose two ends cooperate with said single electrical connector.

10. Contact strip according to any one of the preceding claims, characterized in that the strip comprises at least two electrically conductive elements, a first electrically conductive element being turned towards the catenary in normal operation of the vehicle so as to provide a first degree of warning, while at least one other electrically conductive element is interposed between said first electrically conductive element and said conduit, so as to provide at least one other degree of warning.

11. Railway vehicle (300) comprising a body (306) and a pantograph (308), said pantograph comprising a frame mounted on said body of said vehicle, a contact strip (1, 1') intended to come into contact with a catenary and means of connection between the frame and the contact strip, characterized in that the contact strip conforms to any one of the preceding claims, and the vehicle further comprises - a pneumatic detection circuit (45) incorporating said detection conduit (4), as well as identification means (46) suitable for identifying a pressure variation in said pneumatic circuit, - at least one electrical detection circuit (8, 8') incorporating said at least one electrically conductive element (5), as well as detection means (91), suitable for detecting the variation of a parameter representative of said detection circuit, such as the electrical interruption of said detection circuit, and - warning means (92) capable of being activated when said variation is outside a predetermined range of responses, in particular in the event of an electrical interruption of said detection circuit.

12. Vehicle according to the preceding claim, characterized in that it further comprises a control / command module (9) integrating detection means and warning means, this module being capable of cooperating with said electrical detection circuit (8, 8').

13. Vehicle according to claim 12, characterized in that said control / command module (9) includes wireless communication means (93), suitable for transmitting information towards said railway vehicle and / or the ground, said control / command module (9) being fixed, in particular in a removable manner, on the head (109) of the pantograph.

14. Method for monitoring the wear of a contact strip according to any one of claims 1 to 10, mounted on a vehicle according to any one of claims 11 to 13, wherein: - the variation of a parameter representative of said electrical detection circuit (8), such as the electrical interruption of said detection circuit, is detected; - a contact of the electrically conductive element (5) with the catenary (304) is deduced ; and in which - a first characteristic time (t1) is determined, corresponding to the contact of the electrically conductive element with the catenary, - a second characteristic time (t2) is estimated, corresponding to the contact of the conduit with the catenary, - a so-called safety service duration is estimated, corresponding to the difference (t2-t1) between the second characteristic time and the first characteristic time.

15. Method for improving a railway vehicle (300) comprising a body (306) and a pantograph (308), said pantograph comprising a chassis mounted on said body of said vehicle, at least one contact strip called the original contact strip, intended to come into contact with a catenary and means of connection between the chassis and the contact strip, said contact strip comprising means for fixing to said pantograph, in particular a bracket, as well as a wear strip intended to come into contact with a catenary (304), this wear strip being made of a first electrically conductive material, said contact strip further comprising a conduit, called a pneumatic detection conduit, adapted to contain a fluid under pressure, and connecting means suitable for linking this pneumatic detection conduit to a pneumatic detection circuit, characterized in that - said at least one original contact strip is replaced by a contact strip (1, 1') conforming to any one of claims 1 to 10, referred to hereafter as the replacement contact strip, - said vehicle is equipped with at least one electrical detection circuit (8) and with detection means (9) suitable for detecting the variation of a parameter representative of said detection circuit, such as the electrical interruption of said detection circuit, - said at least one electrically conductive element (5) of said replacement contact strip is connected with said electrical detection circuit (8).