Method for obtaining underfloor heating for vehicles, and underfloor heating for vehicles

Abstract

The present invention relates to a method for obtaining underfloor heating for vehicles, in particular rail vehicles, comprising a core (4) between an upper panel (50), intended to be covered with a floor covering, and a lower panel (51), as well as a heating film (6) between the upper panel (50) and the core (4), the heating film comprising a support (8) which has through-holes and a heating element (9) that consists of an electrically conductive wire and is attached to one of the two faces of the support, the wire extending in a determined pattern, the method comprising the following steps: - a step of forming a stack comprising at least the heating film and the core (4), the heating element of the heating film being arranged between the core and the support of the heating film; - a step of depositing a layer of adhesive between the heating film and the core (4); and - a step of compressing the stack, after which the heating element is pressed into the core in such a way that the percentage of its outer surface located inside the core is between 20 % and 90 %.

Description

Description Title of the invention: METHOD FOR OBTAINING A HEATED FLOOR FOR VEHICLES, AND HEATED FLOOR FOR VEHICLES [1] The present invention relates to the technical field of heating films intended for a heated floor for a vehicle and heated floors for a vehicle, in particular a railway vehicle. [2] As is known, such a floor comprises a core which may be a honeycomb or cellular structure, foam, wood or composite, between an upper panel and a lower panel, generally made of aluminium or composite. All these elements are glued together using a suitable adhesive. [3] On the upper panel of the floor is usually provided a floor covering and, under the lower panel, a layer of thermal insulation. [4] A heating film is provided between the underside of the lower panel and the thermal insulation layer. The latter thermally insulates the heating film from the external environment of the floor. [5] Such floors are described for example in document CN 102180175. [6] They have the disadvantage of being complex to make and having relatively low thermal performance, since the thermal energy must pass through the entire floor structure before reaching the room to be heated. [7] This is why patent FR3086626 describes a heated floor for a railway vehicle which comprises a heating film glued between the upper panel and the core of the floor. [8] This floor allows the railway vehicle to be heated better, while avoiding or limiting the presence of thermal insulation under the lower face of the lower floor panel. [9] This heating film comprises a heating element in the form of a heating conductive track which is placed flat between at least two layers of polyester, a layer of polyurethane covering each of the polyester layers placed on the outside.

[0010] These polyurethane layers ensure good adhesion of the heating film to the other floor elements, while allowing the use of conventional glues.

[0011] This floor provides satisfaction but has the disadvantage of using a heating film requiring several layers of different materials to allow it to be bonded to the other elements of the floor.

[0012] Document W02021 / 005465 describes a heated floor intended for means of transport also comprising a heating film between its upper panel and its core. This heating film is formed of a net on which a heating cable is fixed, the latter being in contact with the upper panel.

[0013] This floor is designed to optimize heat transmission between the heating cable and the top panel but requires a significant amount of adhesive to secure the panel components together.

[0014] Furthermore, new requirements have emerged, in particular that of having heating films which, in use, generate differentiated heat on their surface or which have a complex shaped outline.

[0015] The object of the invention is to overcome these drawbacks by proposing a method for obtaining a heated floor for vehicles, particularly railway vehicles, the implementation of which is simplified and which makes it possible to limit the quantity of adhesive used while ensuring good adhesion of the floor elements and using traditional glues.

[0016] The invention also aims to provide a heated floor for vehicles, particularly railway vehicles, whose cost price and weight are reduced and which allows the railway vehicle to be heated better, while having mechanical characteristics similar to those of known floors.

[0017] The invention thus relates to a method for obtaining a heated floor for vehicles, in particular railway vehicles, comprising a core between an upper panel intended to be covered with a floor covering and a lower panel, as well as a heating film between said upper panel and said core, said film heating device comprising a support which has through holes and a heating element consisting of an electrically conductive wire and fixed on one of the two faces of said support, said wire extending in a determined pattern, said method comprising the following steps: - A step of forming a stack comprising at least said heating film and said core, in which the heating element of said heating film is arranged between said core and the support of said heating film, - A step of depositing a layer of adhesive between the heating film and said core and - A step of compressing the stack at the end of which said heating element is pushed into said core, such that the percentage of its external surface located inside the core is between 20% and 90% and, preferably, between 40% and 60%.

[0018] The pressure applied to the stack is between 10 and 1000 psi and preferably between 100 and 500 psi.

[0019] In a variant, the method comprises, after the compression step, a step of positioning said lower panel on said core, on the side opposite the heating film, and said upper panel on said support of said heating film, a layer of adhesive being deposited between said upper panel and said support and between said lower panel and said core.

[0020] In another variant, the stack also comprises said top panel and said bottom panel, a layer of adhesive being deposited between said top panel and said support and between said bottom panel and said core.

[0021] In yet another variant, the stack is formed in a mold and successively comprises a layer of polymerizable resin deposited at the bottom of the mold and at least one layer of threads / fibers placed in the resin, said core and said heating film, and at least one layer of threads / fibers coated with a layer of resin, the compression step making it possible to obtain the polymerization of the resin, said upper panel and said lower panel each being formed by at least one layer of threads / fibers and polymerized resin.

[0022] In this latter variant, the support of the heating film can be made of the same material as said layers of wires / fibers.

[0023] The method according to the invention may also advantageously have one and / or other of the following characteristics: the heating wire is fixed to said support by gluing or sewing; the heating element has a diameter of between 0.01 mm and 3 mm and, preferably, between 0.1 mm and 0.8 mm; the support is formed from a combination of wires and / or fibers providing free spaces between them through the support; the support is formed from a lattice or a grid; the heating element has a variable density of wires on its surface; the core is plastically deformable under the effect of compression.

[0024] The invention also relates to a heated floor for railway vehicles comprising a core between an upper panel intended to be covered with a floor covering and a lower panel, as well as a heating film, glued between said upper panel and said core, said heating film comprising a support which has through holes and a heating element consisting of an electrically conductive wire and fixed on one of the two faces of said support, said wire extending according to a determined pattern, characterized in that said support is arranged between said upper panel and said heating element and in that said heating element is embedded in said core, the percentage of its external surface located inside the core being between 20% and 90% and, preferably, between 40% and 60%.

[0025] The floor according to the invention may also advantageously have one and / or other of the following characteristics: - the core of the floor is a honeycomb or cellular structure or foam, made of a plastic or composite material, or a structure of wood, cork or composite; - the upper panel and / or the lower panel can be made of a metallic, composite or plastic material, or even of wood; - the adhesive used to stick the elements inside the floor is based on polyester, polyether or polyurethane; - the thickness of the space between the upper panel and the core is of the order of a few tenths of a millimeter.

[0026] The invention will be better understood and other aims, advantages and characteristics thereof will appear more clearly on reading the description which follows and which is made with regard to the following figures in which:

[0027] [Fig. 1], a schematic sectional view of an example of underfloor heating according to the invention;

[0028] [Fig. 2], a schematic front view illustrating an example of a support for a heating film according to the invention;

[0029] [Fig. 3], a schematic front view illustrating an example of a heating film according to the invention comprising the support illustrated in Figure 2 and a conductive wire distributed according to a given pattern;

[0030] [Fig. 4], a detail of Figure 3 showing the fixing of the conductive wire on the support;

[0031] [Fig. 5], a diagram giving on the abscissa, the half-width of a first example of heating film according to the invention and on the ordinate the surface temperature of the heating film, in use, this first example of film comprising a uniform density of conductive wires on the surface of the heating element;

[0032] [Fig. 6], a diagram giving on the abscissa, the half-width of a second example of heating film according to the invention and on the ordinate the surface temperature of the heating film, in use, this second example of film comprising a variable density of conductive wires on the surface of the heating element;

[0033] [Fig.7] and [Fig.8] are schematic views illustrating two steps of the method according to the invention

[0034] [Fig.9] and [Fig.10] are schematic views illustrating the steps of an alternative implementation of the method according to the invention;

[0035] [Fig. 11] to [Fig. 16] are schematic views illustrating another variant of implementation of the method according to the invention.

[0036] Figure 1 illustrates a floor 1 which is mounted on the structure 72 of a vehicle, in this example a railway vehicle, by means of suspension means 73, which are mechanical decouplers.

[0037] This floor 1 comprises a core 4, for example in the form of a cellular or honeycomb structure, between an upper panel 50 and a lower panel 51.

[0038] As illustrated in Figure 1, the upper panel 50 of the floor is covered, on its upper face 500, with a floor covering 70 since it is located towards the inside of the railway vehicle, while the lower panel 51 will be located on the side of the track on which the railway vehicle will roll.

[0039] Figure 1 also shows that a heating film 6 is located between the upper panel 50 of the floor and the honeycomb structure 4.

[0040] Thus, with the floor according to the invention, the heating film 6 is an integral part of the structure of the floor.

[0041] However, this floor is subject to significant mechanical constraints, in particular vibrations generated inside the vehicle when it is moving.

[0042] With the structure illustrated in Figure 1, the heating film is located as close as possible to the vehicle's passenger compartment, allowing it to be heated much more quickly than when the film is located under the underside of the lower floor panel.

[0043] Furthermore, this positioning makes it possible to benefit from the thermal insulation provided by the core 4 of the floor. It therefore becomes unnecessary to provide thermal insulation under the lower face 510 of the lower panel 51, as in a conventional heated floor.

[0044] Thus, reference 71 designates a layer of acoustic insulation which is only provided in the areas where the bogies are located, when it is a railway vehicle. It is therefore understood that this layer 71 plays no role in the insulation of the heating film and / or in the thermal performance of the floor.

[0045] The core 4 can be made of a plastic material or even wood or composite. It can notably be a polyester (PET) or polyethylene foam whose thickness is for example between 35 and 10 millimeters, or even balsa.

[0046] This core has mechanical and thermal characteristics which are a function of its structure, its thickness and its constituent material. In a way Generally, as will be explained later, this core must allow the conductive wire to be pushed in under pressure and it is made of a material capable of local deformation, preferably plastic. Each of the panels 50 and 51 can be made of a metallic, composite or plastic material or even wood.

[0047] Thus, these panels can be made of a composite material based on resin and fibers or even of an aluminum sheet. In the latter case, the thickness of the upper panel 50 can be chosen between 1 and 2.5 mm, while the thickness of the lower panel 51 can be chosen between 1 and 1.5 mm.

[0048] The floor covering 7 may, for example, be made of rubber and have a thickness of at least 2 mm.

[0049] Finally, the heating film 6 is in the form of a thin layer whose thickness is between 0.02 and 4 mm.

[0050] In the example illustrated in Figure 1, the floor is flat. However, the invention is not limited to this embodiment and it could include different levels or curved surface portions.

[0051] In the example illustrated in Figures 2 to 4, the heating film comprises a flat support 8 having the shape of a grid or a lattice, consisting here of an assembly of two series of wires 80 and 81, arranged perpendicular to each other.

[0052] This flat support supports a heating element 9 which consists of an electrically conductive wire 90, fixed to said support according to a determined pattern. This heating element extends over only one of the two flat faces of the support.

[0053] This grid can be obtained by weaving natural and / or synthetic threads or by pressing a plastic material.

[0054] It creates empty spaces between the threads, in other words, stitches. These stitches, in this example, have a square shape, with one side having a value, for example, between 1 and 20 mm.

[0055] Generally, the mesh dimensions are chosen so that the glue that will be used can easily penetrate through them.

[0056] The invention is not limited to this embodiment and the grid may be made of wires interlaced in any manner, whether these wires are woven or welded together.

[0057] Thus, in general, the flat support can be formed from any material extending in a sheet and having through holes for the passage of the glue, this material being more thermally insulating than the conductive wire 90.

[0058] For example, it could be a combination of threads and / or fibers that leave free spaces between them through the support, for example a non-woven fabric or a fabric with a loose weave.

[0059] Examples include, but are not limited to, materials marketed under the name TDS by the company SMI Isolation (fiberglass grid) or under the name Quattro Ceramic (stretch fabric) by the company Physiokontact.

[0060] We can also consider a support made of a waterproof material, such as a plastic film, for example polyurethane, which is pierced with through holes.

[0061] The thickness of this support is between 0.01 and 3 mm and preferably between 0.05 and 1 mm.

[0062] In the example illustrated in Figures 2 and 3, the flat support has the shape of a square. However, the invention is not limited to this embodiment and the support can have any shape.

[0063] It should be noted that in the example illustrated, no element is fixed to this heating element, after its fixing on a face of the support 8 and before its use in a floor.

[0064] This conductive wire has a core made of an electrically conductive material and an electrically insulating sheath which surrounds the core.

[0065] The material constituting the core can be, for example, steel, stainless steel, copper, carbon, aluminum or any other conductive material.

[0066] The core of the wire can be in the form of a single strand or a multi-strand.

[0067] It may also include a reinforcing element such as a Kevlar® or fiberglass braid.

[0068] The material of the sheath can be any electrical insulator, for example PVC, silicone or Teflon. It is chosen according to the desired temperature resistance.

[0069] The heating element has a diameter, for example, between 0.01 mm and 3 mm and, preferably, between 0.1 mm and 0.8 mm or between 0.1 mm and 0.5 mm.

[0070] In the example illustrated in Figure 2, the conductive wire 90 extends over substantially the entire surface of the support 8 and is distributed into five zones: the lateral zones 91 to 94 located on each of the sides of the support 8 and a central zone 95 located in the center of the support.

[0071] In each of these areas, the wire is arranged to form a sinusoid.

[0072] If we refer for example to the central zone 95, the wire 90 thus comprises a series of straight parts 950, a first series of curved sections 951 and a second series of curved sections 952.

[0073] Each curved section 951 of the first series connects a first end of a straight section 950 to a first end of another adjacent straight section 950.

[0074] Each curved section 952 of the second series connects a second end, opposite the first, of a straight section 950 to a second end, opposite the first, of an adjacent straight section 950.

[0075] The other zones 91 to 94 are not described in detail because this description would be similar to that made for the central zone 95.

[0076] Each of the two free ends 900, 901 of the conductive wire 90 is intended to be connected to a power supply (not shown).

[0077] The current intensity is typically between 0.1 and 30 Amps, without this being limiting.

[0078] The wire 90 is fixed to the support 8 by any suitable means and in particular by sewing or gluing.

[0079] The following glues can be used, for example: transfer glue, hot glue or two-component glue.

[0080] The wire can also be fixed to the support by means of sewing.

[0081] Figure 4 shows a detail of Figure 3 located at a curved section 951. This seam is made in a conventional manner so as to allow the connection of the conductive thread 90 with the support 8. In the example illustrated in Figure 4, the seam 902 is zig-zag. A standard industrial sewing machine can make this seam.

[0082] Of course, the invention is not limited to this type of sewing.

[0083] Figure 2 also shows that the spacing between the straight parts of the sinusoids in a zone can vary from one zone to another. Thus, this spacing is greater in the central zone 95 than for the lateral zones 91 to 94. This spacing makes it possible to adjust the density of the wire in each zone. In the example illustrated in Figure 2, this density is greater in the lateral zones than in the central zone.

[0084] This constitutes an advantage of the heating film according to the invention. Indeed, the wire has a diameter such that it can be easily bent without being damaged. This makes it possible to position the wire according to a pattern having curved parts, such as a sinusoid, and also to increase the density of the wire by adapting the pattern accordingly.

[0085] A heating film according to the invention makes it possible to obtain a power per surface of between 50 and 5000 W / m 2 .

[0086] The interest of modulating the density of the thread will now be explained with reference to figures 5 and 6.

[0087] These figures give, on the ordinate and in degrees C°, the surface temperature of the heating film when it is supplied with electric current, as a function of the half-width, that is to say the distance in meters between the center of the support and one of its edges, on the abscissa.

[0088] The curve in Figure 5 corresponds to a heating film according to the invention having a uniform conductive wire density on the surface of the support.

[0089] It shows that, in this situation, the surface temperature of the support decreases from the center to the edge of the support and thus goes from 30°C to 23°C.

[0090] The curve in Figure 6 corresponds to a heating film according to the invention having a differentiated density of conductive wire on the surface of the support, the density being greater on the edges of the support than in its central part. It is therefore a heating film of the type illustrated in Figures 2 and 3.

[0091] The curve in Figure 6 shows that with such a film, the surface temperature of the support is kept constant over half the width of the support and that it only decreases from 30°C to 25.5°C.

[0092] It is therefore understood that by making it possible to adapt the density of conductive wire in the heating film, the invention makes it possible to obtain films and heated floors which will provide greater comfort to users.

[0093] It should also be noted that the use of a small diameter conductive wire to make the heating element allows the production of heating films of any shape, for example with numerous cutouts. Indeed, it will be possible to determine a pattern for the wire, adapted to the shape of this support and ensuring a density of conductive wire suitable for the application in question.

[0094] In the examples illustrated in Figures 2 to 4, the support of the heating film is flat. However, the support could also have a three-dimensional shape to be adapted to the shape of the floor in which it will be inserted. This three-dimensional shape can also be obtained when using the heating film, the latter being sufficiently flexible to adapt to the shape required for the floor.

[0095] We will now focus on the bonding of the heating film according to the invention between the upper panel 50 of the floor and the core 4.

[0096] The process for obtaining a heated floor includes several implementation variants, all of which include the steps schematically illustrated in Figures 7 and 8.

[0097] Figure 7 illustrates a step of forming a stack comprising at least one heating film 6 and a core 4, in which the heating element 9 of the heating film is arranged between the core and the support 8 of the heating film. A layer of adhesive 4a is deposited between the heating film and said core 4.

[0098] This layer of adhesive can be deposited on the core before the heating film is placed, on the heating film after it is placed on the core, or even be already present in a mold.

[0099] Once the stack is completed, it is subjected to compression shown diagrammatically by the two arrows F1 and F2. As illustrated in Figure 8, this leads to the heating element 6 being pushed into the core 4. The latter is deformed to create a hollow structure of the same shape as the heating element. This is possible since the support does not constitute an obstacle between the core and the heating element. This pushing is therefore obtained directly by applying pressure, without it being necessary to first make channels in the core.

[0100] This compression can be conventionally obtained by jacks or by placing the stack under vacuum.

[0101] At the end of this compression step, the percentage of the outer surface of the element located inside the core is between 20% and 90% and, preferably, between 40% and 60%.

[0102] The core material is chosen so that it can deform locally and, preferably, plastically under the effect of pressure exerted by a conductive wire, in particular a metallic one. The pressure applied is between 10 and 1000 psi and will be chosen by the person skilled in the art depending on the material.

[0103] The thickness of the interface between the core and the heating film support is therefore reduced, which also leads to a reduction in the amount of adhesive used. In addition, the hollow structure formed in the core is perfectly adapted to the shape of the heating element, so that only a very thin adhesive film can be present between this hollow structure and the heating element. This further contributes to reducing the amount of adhesive used.

[0104] The heated floor according to the invention can then be obtained, from the assembly illustrated in figure 8, by depositing a layer of adhesive on each of the opposite faces of the assembly then by positioning a lower panel on the core and a top panel on the heating film support, to fix these two panels to the assembly. Of course, the adhesive layer could also be deposited on each of the panels.

[0105] As illustrated in Figures 9 and 10, the heated floor according to the invention can also be obtained from a stack comprising a lower panel 51, a core 4, a heating film 6 whose heating element 9 is arranged between the core and the support 8 of the heating film and an upper panel 50. A layer of adhesive is deposited between the different constituent elements of the stack, only the layer 4a present between the core and the upper panel being illustrated.

[0106] This stack is then subjected to compression illustrated schematically by the arrows F1 and F2, and Figure 10 illustrates the heated floor obtained. As has already been illustrated and described with reference to Figure 8, at the end of this compression step, the heating element is pushed into the core 4, the percentage of the outer surface of the element located inside the core is between 20% and 90% and, preferably, between 40% and 60%. The compression can be, for example, obtained using jacks.

[0107] The adhesive can be chosen from glues based on polyester, polyether or polyurethane, which are perfectly effective for fixing, for example, core 4 to the lower and upper panels of the floor. Any other railway-certified glue could also be used.

[0108] The thickness of the gap between the top panel and the core is a few tenths of a mm. The thickness of the adhesive layer is less than that of this gap, due to the presence of the heating film.

[0109] Since the heating film 6 only has one support and this support has through holes, the adhesive can, on the one hand, easily penetrate through the support and, on the other hand, surround the conductive wire forming the heating element.

[0110] Thus, there is no obstacle to the heating film 6 being able to be glued inside the structure of the floor 1 using the adhesives that are conventionally used in the railway sector for the construction of floors. As indicated above, these include adhesives based on polyester, polyether or polyurethane.

[0111] Another variant of the method according to the invention is illustrated in Figures 11 to 15, this variant using a mold 2.

[0112] According to Figure 11, a polymerizable resin is first poured into this mold. In this layer of resin 30a are deposited several layers of threads or fibers 30 (only two layers are illustrated).

[0113] On the last layer of fibers 30 deposited, a heating film 6 is then deposited, such that the support 8 of the heating film is in contact with this last layer of fibers, as illustrated in figure 12.

[0114] Figure 13 shows that the core 4 of the floor is then placed on the heating element 9 of the heating film.

[0115] The stack is completed by the deposition of a layer of resin 31a and several layers of fibers 31 on the free surface of the core, therefore on the side opposite the heating film (figure 14).

[0116] The mold 2 is then closed and placed under vacuum using the pump 20 (figure 15). The stack is then subjected to pressure, which leads to the heating element being pushed into the core 4, as described with reference to figure 8. The percentage of the outer surface of the element located inside the core is between 20% and 90% and, preferably, between 40% and 60%.

[0117] Furthermore, during this vacuum, the resin polymerizes and then forms, with the layers of fibers 30, the upper panel 51 of the heated floor and, with the layers of fibers 31, the lower panel 50 of the heated floor obtained which is illustrated in figure 16. These two panels are therefore made of composite material.

[0118] Of course, the position of the core and the heating film in the stack could be reversed, the core then being deposited on the layers of fibers 30 impregnated with resin and the layers of wires or fibers 31 impregnated with resin on the support of the heating film. The polymerized resin then forms with the layers of fibers 30, the lower panel 51 of the floor, while it forms with the layers of fibers 31, the upper panel 50.

[0119] Compression inside the mold could be achieved by means other than vacuuming.

[0120] The support 8 of the heating film is advantageously of the same nature and structure as the layers of fibers used in the stack. In other words, the heating element is then fixed on one of the layers of fibers of the stack.

[0121] The threads or fibers used may in particular be glass fibers, carbon fibers, or even synthetic fibers. Generally speaking, any fiber or thread that can be impregnated with resin may be used. Furthermore, the layers 30 and / or 31 may or may not be formed from fibers of the same nature.

[0122] Furthermore, the method is not limited to the described example and either or both panels could comprise only one layer of yarns / fibers.

[0123] The resins used are, for example, polyester, polyether, epoxy, polyurethane resins. Generally speaking, any resin that can impregnate a fiber and form a rigid element after polymerization can be used.

[0124] Generally, the duration of the compression step is between 2 and 60 minutes and the pressure to which the stack is subjected is between 10 and 1000 psi and, preferably between 100 and 500 psi or between 300 and 500 psi.

[0125] The method according to the invention has the advantage of avoiding the prior formation of channels in the core, intended to receive the heating element. Indeed, the heating element is pushed into the core due to the application of pressure, the core deforming locally. This considerably simplifies the implementation of the method. Furthermore, the hollow structure formed by the application of pressure is perfectly adapted to the shape of the heating element, which limits the quantity of adhesive used and therefore the weight of the floor, without compromising the fixing of the various elements of the floor.

[0126] It allows the amount of adhesive used to be reduced even further compared to a floor that does not have channels previously made in the core.

[0127] In fact, in such a floor, the heating element of the heating film is present over its entire height between the top panel and the core of the floor and the adhesive must be in sufficient quantity to fill the space between the top panel and the core.

[0128] In practice, with a heating wire of diameter 0.8 mm and a support whose thickness is 0.25 mm, the volume of adhesive in the space between the top panel and the core is approximately 0.00105 m 3 for 1 m 2 floor. The adhesive mass is then 1680 g / m 2 of flooring, for an adhesive with a density of 1600. This volume of adhesive is reduced to approximately 0.00065 m 3 for 1 m 2floor, with a heated floor according to the invention in which the heating element is embedded in the core over half its diameter (the quantity of adhesive present between the heating element and the hollow structure is neglected in this calculation). The mass of adhesive is then 1040 g / m 2 floor.

[0129] Thus, with a heated floor according to the invention, the weight saving of adhesive is at least around 40%, since the wire can be pushed even deeper into the core. This allows both material savings and a reduction in the weight of the heated floor.

[0130] Furthermore, the tests carried out show that, contrary to what was expected, the presence of a thermally insulating layer, formed of adhesive and the support of the heating film, does not hinder the diffusion of heat between the heating element and the upper panel. This is probably due to the low thickness of this insulating layer. In addition, it appears that it allows uniform diffusion of heat towards the upper panel, avoiding the creation of hot spots.

[0131] In the examples of implementation of the method according to the invention which have just been described, the heated floor obtained is flat, like the heating film used. However, the invention is not limited to these examples and the method could be used to produce floors whose upper face is not flat but three-dimensional.

[0132] Thus, providing the heating film inside the floor structure does not modify the manufacturing techniques which are conventionally used for floors which do not have a heating film in their structure.

[0133] Furthermore, the fixing of the heating film is resistant over time, despite the vibrations to which the vehicle is subjected.

[0134] This solution therefore avoids the use of glues other than those commonly used for the construction of railway floors, which benefit from all the certifications for this market or other processes which would both be detrimental to the mechanical resistance of the floor.

[0135] Furthermore, compared to the heating film described in patent FR3086626, the structure of the heating film according to the invention is very simplified since it is no longer necessary to provide a layer of polyurethane on each of the support layers, between which the heating element is placed.

[0136] It can also be noted that the floor according to the invention has fire or smoke performance similar to that of a floor without a heating film. In fact, the quantity of polyurethane introduced into the structure of the floor is very low, the thickness of the polyurethane layers being of the order of a few microns.

[0137] Thus, the heated floor according to the invention is simplified in construction since it avoids the use of a layer of thermal insulation under the floor, while presenting greater heating performances than conventional floors and mechanical performances similar to them.

[0138] The invention is not limited to the embodiment of the heated floor which has just been described. In particular, the materials constituting the different elements described may vary.

Claims

Demands

1. A method for obtaining a heated floor for vehicles, in particular railway vehicles, comprising a core (4) between an upper panel (50) intended to be covered with a floor covering and a lower panel (51), and a heating film (6) between said upper panel (50) and said core (4), said heating film comprising a support (8) having through holes and a heating element (9) consisting of an electrically conductive wire fixed to one of the two faces of said support, said wire extending in a determined pattern, said method comprising the following steps: A step in forming a stack comprising at least said heating film and said core (4), wherein the heating element (9) of said heating film is disposed between said core and the support (8) of said heating film, A step of depositing a layer of adhesive between the heating film (6) and said core (4) and A stack compression step at the end of which said heating element is pressed into said core, such that the percentage of its outer surface located inside the core is between 20% and 90%.

2. A method according to claim 1, characterized in that the pressure applied to the stack is between 10 and 1000 psi and, preferably, between 100 and 500 psi.

3. A method according to any one of claims 1 or 2, characterized in that it comprises, after the compression step, a positioning step of said lower panel (51) on said core (4), on the side opposite the heating film, and of said upper panel (50) on said support of said heating film, a layer of adhesive being deposited between said upper panel (50) and said support and between said lower panel (51) and said core (4).

4. A method according to claim 1 or 2, characterized in that the stack also comprises said upper panel (50) and said lower panel (51), a layer of adhesive being deposited between said upper panel and said support and between said lower panel (50) and said core (4).

5. A method according to claim 1 or 2, characterized in that the stack is formed in a mold (2) and successively comprises a layer of polymerizable resin (30a) deposited at the bottom of the mold and at least one layer of yarns / fibers (30) placed in the resin, said core (4) and said heating film (6), and at least one layer of yarns / fibers (31) coated with a layer of resin (31a), the compression step enabling the polymerization of the resin, said upper panel (50) and said lower panel (51) each being formed by at least one layer of yarns / fibers and polymerized resin.

6. Method according to claim 5, characterized in that the support of the heating film is made of the same material as said layers of wires / fibers.

7. A method according to any one of claims 1 to 6, characterized in that the heating wire is fixed to said support by gluing or sewing.

8. A method according to any one of claims 1 to 7, characterized in that the support is formed of an association of yarns and / or fibers providing free spaces between them through the support.

9. A method according to any one of claims 1 to 8, characterized in that the heating element has a variable wire density on its surface.

10. A heated floor for railway vehicles comprising a core (4) between an upper panel (50) intended to be covered with a floor covering and a lower panel (51), and a heating film bonded between said upper panel (50) and said core (4), said heating film comprising a support having through holes and a heating element (9) consisting of an electrically conductive wire and fixed to one of the two faces of said support, said wire extending in a determined pattern, characterized in that said support (8) is disposed between said upper panel (50) and said heating element (9) and in that said heating element (9) is embedded in said core (4), the percentage of its outer surface located inside the core being between 20% and 90%.

11. Floor according to claim 10, characterized in that the core (4) is a cellular or honeycomb structure, or even a foam structure, made of a plastic or composite material, or even a wood, cork or composite structure.

12. Floor according to claim 10 or 11, characterized in that the upper panel and the lower panel can be made of a metallic, composite or plastic material, or even of wood.

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