Abstract:
A medium for a rolling stock electric current collection strip is provided. The medium is suitable for holding said strip and transmitting the current passing through the strip to the rolling stock. The medium includes a base and at least two walls forming a space suitable for at least partially accommodating the strip. The medium includes at least one elastic means suitable for clamping the strip against the base.

Description:
BACKGROUND 
     The invention relates to a support for a current collector strip and more particularly a collector strip for a rolling stock vehicle. 
     The invention is equally suitable for a current collector strip of a pantograph rubbing on a catenary or that of a shoe rubbing on a rail. 
     At the present time, in order for a rolling stock vehicle to be supplied by an external current source, one of the techniques is to use a third rail, generally used in railway transport vehicles, such as subway vehicles, district trains, etc. 
     This third rail allows the current to be transmitted to the rolling stock vehicle by means of sliding shoes that collect the current and transfer it to the vehicle. 
     These shoes are made up in particular of a support, also called a yoke, onto which a collector strip, generally a carbon collector strip, is crimped. 
     To hold the collector strip in place on the yoke, the carbon strip is machined so as to provide a dovetail assembly with the edges of the yoke. 
     The support comprises a device for fastening to the rolling stock vehicle, generally a set of bolts. 
     The shoe thus assembled is then dipped into a bath of molten tin to braze the carbon strip to the yoke so as to ensure that there is good conductivity between the collector strip and the support. 
     It is the shoe thus assembled which is mounted on the rolling stock vehicle. 
     The carbon collector strip, sliding on the third rail in order to collect the current, is continuously worn away and requires to be changed regularly. Since the collector strip is irremovably fastened to the yoke, it is necessary to change the entire shoe, yoke and collector strip assembly, especially by dismantling all the bolts connecting it to the vehicle. 
     Since the collector strip is inseparable from the support, it is necessary to strip down the assembly, which represents a relatively high cost. 
     The operation of fitting/dismantling the shoe on the rolling stock vehicle is relatively lengthy since it requires the bolts joining the shoe to the vehicle to be fastened/unfastened. 
     The known devices may therefore be relatively expensive, lead to a “loss” of material, especially if the support is changed with each new collector strip, may require a long time for changes or maintenance, and many dismantling steps, and/or may not be sufficiently resistant, especially corrosion-resistant. 
     SUMMARY 
     The object of the invention is to remedy all or some of the abovementioned problems and in particular to provide a support for a collector strip that enables the said strip to be easily assembled on the rolling stock vehicle, while being able to be reused. 
     According to a first aspect, one subject of the invention is a support for a current collector strip of a rolling stock vehicle, said support being suitable for holding said strip in place and for transmitting the current passing through it to the rolling stock vehicle, said support comprising a base and at least two walls defining a space suitable for partially accommodating the strip, said support comprising at least one elastic means suitable for clamping said strip against said base. 
     More particularly, the strip is clamped against the base solely by the one or more elastic means, that is to say, in particular, no other means cooperates therewith for effecting the clamping operation. 
     The expression “electric rolling stock vehicle” is understood in the context of the present invention to mean any rolling stock vehicle requiring contact with a third rail shoe formed by the support and the collector strip. 
     By clamping the strip to the support it is possible to hold the assembly in place and thus ensure not only good mechanical stability but also good electrical conductivity. 
     In particular, the clamping is effected by a force ranging from 600 to 5000 N, especially 1000 to 1600 N. 
     Advantageously, the walls and/or the at least one elastic means are made of and/or coated with an electrically insulating material. 
     The coating may have a thickness ranging from 0.1 to 2 mm, especially from 0.1 to 1 mm and in particular from 0.1 to 0.5 mm. 
     In particular, the electrically insulating material is a plastic, a rubber, a resin and/or a paint. 
     In particular, the base comprises at least one stud suitable for cooperating with at least one corresponding orifice of the collector strip. 
     The base may comprise at least one lateral stop. 
     According to one particular embodiment, the base comprises two lateral stops. 
     Advantageously, at least one wall comprises at least one part, for example a notch, capable of accommodating a suitable, or complementary, part of the collector strip. 
     Advantageously, each notch is suitable for accommodating at least one elastic means. 
     In particular, the elastic means is a leaf spring. 
     Advantageously, the leaf spring is made of a plastic. 
     Since a current flows through the support, this current may cause, at least in certain parts, the conducting materials to heat up and thus reduce their mechanical properties. 
     By using an electrically insulating material as elastic means, or as a coating for the elastic means, it is possible for said elastic means not to be heated, or to be heated less, due to the flow of the current and therefore it is possible to maintain the desired mechanical properties, especially flexibility properties, for a longer time. 
     According to one particular embodiment, each notch is suitable for accommodating at least one locking means for locking the collector strip. 
     Advantageously, the locking means is a rod suitable for penetrating a corresponding orifice of the collector strip. 
     In particular, the elastic means is at least partly located at the junction between the bottom and the walls. 
     According to a first embodiment, the bottom and the walls are formed from a single piece, the elastic means providing from a mechanical property at the junction between the base and the walls. 
     According to a second embodiment, the base and the walls are separate pieces, these being connected by an intermediate piece forming a elastic connection. 
     According to one particular embodiment, the free ends of the walls each comprise an edge, notably arranged to allow moving apart the free ends of the walls. 
     The collector strip is most particularly a carbon-based strip. 
     The invention also relates to a current-collecting device comprising a support according to the invention and a collector strip held in place by the latter. This device may be a shoe or a pantograph. 
     Advantageously, the current-collecting device comprises an adhesive means between the collector strip and the support. 
     Notably, this adhesive means is suitable for securing the collector strip in the event of dislocation. 
     A dislocation may occur after a shock and more particularly after wear of the collector strip due to its rubbing, which reduces its thickness and therefore its mechanical strength. Dislocation of the strip may lead to the loss of fragments that run the risk of impairing the proper operation of the electric vehicle. 
     In particular, the adhesive means is positioned so as to form a contact between the base and the strip. 
     Advantageously, the adhesive means comprises a single-sided adhesive tape positioned so as to be in contact with just the strip. 
     In particular, the adhesive means is suitable for withstanding a temperature of between 100 and 500° C., preferably at least 150° C. 
     The adhesion of the collector strip to the support will preferably be effected at ambient temperature and will advantageously be of low enough force to allow easy dismantling and cleaning during an operation to change the strip. 
     According to a first embodiment, the adhesive means will for example be an adhesive tape bonded to the collector strip. In particular, the adhesive tape may be chosen from one or more of the following compounds: elastomer, cyanoacrylates, polyvinyl acetate and urea-formaldehyde. More particularly, the adhesive tape may be reinforced with textile or metal fibers. Advantageously, such a metal-based reinforcement helps to improve the electrical conductivity between the carbon strip and the support. The adhesive tape makes it possible in particular to increase the damping capability between the base of the support and the current collector strip. 
     According to another embodiment, the adhesive means is a one-component or two-component liquid adhesive. Advantageously, the adhesive is injected after the strip has been mounted on its support. In particular, the adhesive is chosen from the following elements: two-component epoxy based on bisphenol A, silicone, two-component polyurethane, or acrylic. In particular, it is possible to add an additive to the adhesive in order to facilitate the electrical conductivity, such as graphite or silver powder. 
     A person skilled in the art will be capable of determining which adhesive means is suited to his use. In particular, an adhesive tape will advantageously be used for the purpose of immediately reusing the support with a uniform force of adhesion and good damping capability. A liquid adhesive will require a longer time to mount the strip, but it does provide an adhesive means having better conductivity (addition of an additive). 
     Advantageously, an adhesive tape, bonded solely to the collector strip, will leave no adhesive on the support and therefore will not require a cleaning phase, thus making immediate reuse of the support easier. 
     More particularly, the adhesive means must have a lifetime in use, once assembled with the collector strip, of at least 6 to 7 months, or of at least 80,000 km, in operation. 
     The invention also relates to a method for fastening a collector strip to a support, the method comprising the following steps:
         moving apart the ends of the walls of the support, by means of the edges, sufficiently to be able to insert the collector strip thereinto;   positioning the collector strip in the space defined between the base and the walls of the support; and   releasing the ends of the walls of the support so as to clamp the strip against said base.       

     In particular, the method may comprise, before the collector strip is positioned in the space, the positioning of an adhesive tape on that part of the strip which is in contact with the base. 
     According to another way of implementing the fastening method, it is possible to add, after the ends of the walls have been released, a step of injecting an adhesive into the natural gaps or artificial gaps created between the strip and the support. 
     Depending on the nature of the adhesive means, pressure may be applied and the assembly placed in an oven. 
     The term “artificial gap” will be understood to mean that orifices may be provided in the support for injecting the adhesive. 
     In order for the adhesive to propagate easily, it is possible to provide grooves on that face of the strip which is in contact with the base of the support. 
     The invention also relates to a method for extracting a collector strip from a support, the method comprising the following steps:
         moving apart the ends of the walls of the support, by means of the edges sufficiently to be able to extract the collector strip therefrom;   extracting the collector strip from the space defined between the base and the walls of the support: and   releasing the ends of the walls of the support.       

     When an adhesive means is used, one may break the collector strip before it is extracted, the support then being able to be reused after removal of the adhesive means and cleaning. 
     In one particular application, the support is used as current-collecting shoe for a railway or pneumatic rolling stock vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the nonlimiting drawings in which: 
         FIG. 1  is a view of a first embodiment of the invention; 
         FIGS. 2 and 3  show a second embodiment of the invention; and 
         FIG. 4  is a detailed view of one end of the support shown in  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  shows a first embodiment of a support  10 . 
     According to the first embodiment shown in  FIG. 1 , this comprises a support  10  for a current collector strip  20 . 
     The support  10  comprises a base and two walls  12 ,  13  defining a space suitable for partially accommodating the strip  20 . 
     The collector strip  20  is machined so as to have a shoulder advantageously forming a dovetail profile. 
     The walls  12 ,  13  of the support make an acute angle with the base  11  so that the walls  12 ,  13  are suitable for cooperating with the dovetail profile of the collector strip  20 . According to one particular embodiment, the walls  12 ,  13  of the support  10  form a fillet with the base  11 . 
     In this example, the base  11  and the walls  12 ,  13  are formed from a single piece, the junction between the base  11  and the walls  12 ,  13  being elastic, thus moving the free ends  12 ′,  13 ′ closer one to the other. 
     The elasticity of the junction is a mechanical property that depends on the material used and on the dimensions of the support  10 . 
     In the example, the support  10  is made of steel or stainless steel. 
     Its dimensions may be substantially the following:
         a width ranging from 35 to 70 mm, being 65 mm in the example;   a length ranging from 200 to 300 mm, being 272 mm in the example,   a height ranging from 30 to 60 mm, being 31 mm in the example; and   a thickness ranging from 0.5 to 1.5 mm, being 0.8 mm in the example.       

     It is obvious that a person skilled in the art will adapt the dimensions of the support  10  so as always to maintain sufficient elasticity of the junctions  40 ,  40 ′ so as to allow the strip  20  to be clamped against the bottom  11  via the walls  12 ,  13  bearing on the dovetail profile of said strip  20 . 
     In the example, the overall force exerted by the elatic means is substantially around 1200 N. 
     According to an alternative embodiment, the base  11  and the walls  12 ,  13  are different elements, these being joined together by an element forming a elastic junction  40 ,  40 ′. 
     The walls  12 ,  13  each terminate in an edge  14 ,  15  suitable for withstanding a force able to move the free ends  12 ′,  13 ′ apart. 
     In particular, each edge  14 ,  15  is suitable for cooperating with a tool that exerts a force sufficient to move said ends apart. 
     The amount by which the ends  12 ′,  13 ′ are moved apart must be sufficient to enable the collector strip  20  to be inserted/removed. 
     To fasten the support  10  to a rolling vehicle  1 , the support  10  is drilled right through so as to accommodate a fastening device, especially a device consisting of a bolt  50  and a nut  60 . 
     The second embodiment shown in  FIGS. 2 and 3  comprises a support  10  for a current collector strip  20 . 
     The base  11  comprises a stud  110  suitable for cooperating with a corresponding orifice  210  of the collector strip  20 . 
     The base  11  also comprises two lateral stops  112 ,  112 ′ suitable for blocking the collector strip  20 . 
     The walls  12 ,  13  each comprise a notch  12 ′,  13 ′ suitable for accommodating a part  220 ,  230  of the collector strip  20 . 
     To position the collector strip  20  on the support  20 , said strip  20  is placed substantially at 90° to the support  10  while positioning the orifice  210  of the strip  20  on the stud  110  of the base  10 . 
     Next, the strip  20  is then rotated through one quarter of a turn until it abuts against the lateral stops  112 ,  112 ′. 
     The parts  220 ,  230  of the strip  20  are then inserted into the notches  12 ′,  13 ′ of the walls  12 ,  13 . 
     As may be seen on the wall  13  in  FIG. 3 , an exploded view of which is shown in  FIG. 4 , there is a elastic means consisting of a leaf spring  40 ,  40 ′ suitable for clamping the collector strip  20  against the base  11 . 
     To hold the collector strip  20  in position in the notches  12 ′,  13 ′, at least one support  12 ,  13  includes a locking means  120 . 
     The locking means  120  comprises at least one rod  121  suitable for cooperating with a corresponding orifice  240  of the collector strip  20 . 
     In the example, the rod  121  is forced toward the collector strip  20  by means of a spring (not shown). An inclined part  121 ′ of the rod  121  allows the collector strip  20  to slide over the rod  121 , applying a force on the spring, until the rod  121  enters the corresponding orifice  240  of the collector strip  20 . 
     The rod  121  is put into the position for releasing the collector strip  20  by actuating the release rod  122  which, by means of its inclined part  122 ′ in contact with the secondary inclined part  121 ″, applies force to the spring (not shown) of the rod  121 , thus releasing the collector strip  20 . All that is then required is to rotate the collector strip  20  through a quarter of a turn in order to extract the latter from the notches  12 ′,  13 ′ and therefore from its support  10 . 
     The support  10  is fastened to the rolling stock vehicle  1  by any known means, for example by bolts. 
     A person skilled in the art will readily understand the advantage afforded by these embodiments of a support for a collector strip, in particular saving time when changing the third-rail shoes but also providing a financial saving and an ecological advantage, especially by virtue of the fact of being able to change only the part that has worn out, namely the collector strip. The person skilled in the art will easily be able to adapt such a support for a current collector strip to other uses and especially to pantographs.