Composite tanks with woven shell and corresponding manufacturing methods

Abstract

Heteromorphic composite tank (1) comprising a body that delimits a cavity (5) intended to contain a fluid such as hydrogen, the body comprising a jacket (2) impermeable to the fluid and a woven shell (3) with interlaced plies, the tank (1) being equipped with one or more reinforcements (4) extending through the cavity (5) in such a way as to improve the mechanical strength of the body of the tank (1). Corresponding manufacturing method.

Description

[0001] Description

[0002] Title: Composite tanks with braided shell and corresponding manufacturing processes

[0003] Technical field

[0004] The invention relates to the field of fluid storage, in particular of a fluid forming a fuel contained in a tank of a transport device such as a motor vehicle, an aircraft, a boat, or any other mobile equipment.

[0005] The invention is of particular interest, in no way limiting, in the sector of vehicles using hydrogen or other fuels including, for example, biogas as fuel.

[0006] State of the prior art

[0007] The hydrogen, gas or liquefied gas tanks known in the prior art are generally formed from a body comprising a cylindrical jacket on which pre-impregnated technical fibers, for example carbon, are deposited by filament winding, so as to form a shell capable of resisting the pressure of such a fluid which typically ranges from 2 to 70 MPa in use, with permissible ruptures ranging from 8 to 157.5 MPa at rupture.

[0008] Generally speaking, known reservoirs are bulky, expensive, particularly given the time required to complete the filament winding, and liable to undergo significant deformations under the effect of variations in pressure of the fluid carried.

[0009] Furthermore, known tanks are poorly suited to current and future motor vehicles which, on the one hand, for reasons of mass to be transported, have an increasingly restricted space to accommodate such tanks and, on the other hand, pose problems of energy autonomy.

[0010] Statement of the invention

[0011] The invention aims to remedy the aforementioned problems and in particular to meet the need for additional autonomy of vehicles. A particular aim of the invention is to provide a tank capable of storing a fluid of the biogas or hydrogen type, or more generally of containing a fluid at high pressure.

[0012] Another aim of the invention is to provide a solution making it possible to maximize the useful storage volume with regard to the spaces actually available for this purpose in vehicles such as motor vehicles, aircraft, boats or other mobile equipment.

[0013] For this purpose, the subject of the invention is a tank for a transport device such as a motor vehicle, an aircraft or a boat, comprising a body which delimits a cavity intended to contain a fluid, the body comprising a shell forming an envelope of the tank. According to the invention, the shell comprises an assembly of fibers forming one or more layers each having several plies linked together by some of said fibers, called "binding bias fibers".

[0014] In other words, the tank shell includes a plies interlacing braid, that is to say braided fibers some of which bind different plies together, which makes it possible to obtain excellent mechanical properties in terms of toughness.

[0015] The following document describes the known principles of interlock plies, also known as “3D-interlock”: H. Lansiaux, D. Soulat, F. Boussu and AR Labanieh, Mechanical characterization of 3D warp interlock linen fabrics with different numbers of layers, 24th French Congress of Mechanics, Brest, August 26-30, 2019.

[0016] Such a braiding technique makes it possible to place, at the same time, on a mandrel made to the internal shape of the tank for example, a certain number of braids while interlacing them together in order to avoid, in use, any delamination or any movement between the different braids and thus make them work together.

[0017] This technique also allows the construction of a polymorphic shell, whether it is a shell with a simple or classic geometry of the cylindrical type or a complex heteromorphic geometry.

[0018] A braided fiber shell with interlacing plies makes it possible in particular to improve the fatigue resistance of the tank compared to a shell made by filament winding. The invention makes it possible to produce both high-pressure tanks, with cylindrical or other geometry, and low-pressure tanks such as those, for example, used for carrying liquefied petroleum gas.

[0019] Particularly when the tank has a large dimension or a large diameter in the case of a cylindrical tank, the braided shell of the invention makes it possible to reduce the very large deformations which occur on conventional tanks.

[0020] The shell of the tank of the invention thus forms a texture comprising mainly continuous technical fibers.

[0021] These fibers can be of organic, vegetable, mineral or metallic origin.

[0022] In one embodiment, each of the layers comprises a number NI of plies greater than two, the binding bias fibers passing through a number N2 of plies at least equal to two.

[0023] For example, NI may be equal to five and N2 may be equal to two for at least some of the binding bias fibers.

[0024] In one embodiment, the body includes a liner defining an inner surface that defines the cavity and an outer surface conforming to an inner surface of the shell.

[0025] The liner may include a material such as plastic capable of sealing the liner against fluid contained in the cavity.

[0026] More generally, the shirt may include a material of organic, vegetable, mineral or metallic origin.

[0027] In one embodiment, the reservoir comprises one or more reinforcements which each connect parts of the body arranged opposite each other.

[0028] Depending on the geometry of the body, these parts connected to each other by one or more reinforcements can be flat, convex or concave walls. Such reinforcements make it possible to increase the resistance of the tank to the pressure of the fluid carried in the tank, in particular by increasing the resistance to tensile forces.

[0029] In one embodiment, each of the reinforcements, or at least one of them, may comprise a wall formed in one piece with the jacket.

[0030] In other words, the wall of the reinforcement(s) can form a continuous extension of material with the jacket.

[0031] Generally, each of the reinforcements, or at least one of them, may extend along a bonding direction.

[0032] The direction of connection of each of the reinforcements may be perpendicular or oblique to one and / or the other of the parts of the body which are connected to each other by this reinforcement.

[0033] In one embodiment, each of the reinforcements, or at least one of them, forms a circumferentially closed outer surface around the connection direction along which it extends. Preferably, the entirety of this outer surface delimits the cavity of the reservoir.

[0034] In one embodiment, each of the reinforcements, or at least one of them, forms an internal surface delimiting a hollow space. This hollow space can define an opening passing through the tank in the connection direction.

[0035] In other words, a given reinforcement can include a wall which forms a solid of revolution or more generally a solid closed around the direction of connection which it constitutes.

[0036] By way of non-limiting example, such a reinforcement may have a generally annular or frustoconical geometry, which may be different on different sections of the reinforcement along the connection direction.

[0037] A tank comprising reinforcements forming such hollow spaces can thus form a honeycomb structure, the jacket delimiting a volume comprising the fluid storage cavity crossed by cells formed by the hollow spaces of the reinforcements, in which in particular tie rod type members can be housed.

[0038] In one embodiment, each of the reinforcements, or at least one of them, comprises a tie rod housed in the hollow space formed by said wall of the reinforcement.

[0039] In one embodiment, the tie rod comprises one or more layers made of fibers, the majority of which extend along the bonding direction.

[0040] The tension of the reinforcement(s) can thus form a fibrous texture, which is preferably manufactured using a technique other than interlacing plies. In particular, a majority of fibers can be arranged longitudinally and grouped by light braiding.

[0041] The orientations of the respective fibers of the shell and the tie rod(s) make it possible to respond to loading conditions that are completely different between the body and the reinforcement(s). The reinforcement(s) are in fact particularly exposed to tensile forces when the pressure is internal to the tank. The texture of the body is exposed to all kinds of constraints, namely tensile, bending, compression or even shear forces.

[0042] Among other advantages, the invention makes it possible to manufacture tanks having a resistance to high internal functional pressures, compatible with the carriage of different types of fluid, for example medium pressure natural gas (from 26 MPa in use and 47 MPa at break) or high or very high pressure hydrogen (from 35 to 70 MPa in use and from 78.75 to 157.5 MPa at break), impervious to the fluid carried, in particular when this is a gas having very small molecules such as hydrogen, methane or butane molecules, and having resistance to different types of environment (e.g. acid, basic, humidity, salt fog, etc.), static mechanical to pressure, vibration, shock, endurance, fatigue, aging, fire, ballistic and more generally mechanical, which makes it possible to increase their safety and reliability in use.The invention also relates to a method of manufacturing such a tank, comprising a step of braiding the fibers with interlacing plies so as to form the shell.

[0043] This braiding is preferably carried out on the shirt used as a mandrel.

[0044] In one embodiment, the method comprises, for each of the reinforcement(s), a step of manufacturing the tie rod by braiding the fibers forming this tie rod and a step of inserting the tie rod into the hollow space formed by said wall of the reinforcement.

[0045] The method preferably comprises a step of injecting or infusing a resin into the assembly of fibers forming the shell.

[0046] The fibrous texture can thus be consolidated by resin injection or by any other means.

[0047] Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows.

[0048] Brief description of the drawings

[0049] The following detailed description refers to the attached drawings in which:

[0050] [Fig. 1] is a schematic perspective view, partially cut away, of a tank according to the invention, the tank comprising a body formed of a jacket and a shell made of fibers braided on the jacket, as well as a reinforcement connecting two parts of the body facing each other;

[0051] [Fig. 2] is a partial schematic sectional view of a tank according to the invention and of a tool for assembling a tie rod of a tank reinforcement with the body of this tank;

[0052] [Fig. 3] is a partial schematic sectional view of a layer of the shell of a tank according to the invention, illustrating an example of an assembly of fibers forming this layer;

[0053] [Fig. 4] is a partial schematic sectional view of a tank according to the invention and of a tool for assembling a tie rod of a reinforcement of the tank with the body of this tank, this tank being distinguished in particular from that of figure 2 in that the parts connected to each other by the reinforcement are walls inclined relative to each other and relative to a direction along which the reinforcement extends;

[0054] [Fig. 5] is a partial schematic sectional view of a tank according to the invention and of a tool for assembling a tie rod of a reinforcement of the tank with the body of this tank, this tank being distinguished in particular from that of figure 2 in that the reinforcement comprises diffusers and anti-striction nuts;

[0055] [Fig. 6] is a schematic perspective view, partially cut away, of a tank according to the invention, comprising several reinforcements oriented in a single direction, forming a mono-axial reinforcement network;

[0056] [Fig. 7] is a schematic perspective view, partially cut away, of a tank according to the invention, comprising reinforcements oriented in two mutually orthogonal directions, forming a bi-axial reinforcement network;

[0057] [Fig. 8] is a schematic perspective view, partially cut away, of a tank according to the invention, comprising reinforcements oriented in three mutually orthogonal directions, forming a tri-axial reinforcement network.

[0058] Detailed description of embodiments

[0059] Figures 1 and 6 to 8 include a reference system defining three directions DI, D2 and D3 orthogonal to each other. In this example, DI is a longitudinal direction, D2 a first transverse direction and D3 a second transverse direction.

[0060] Figure 1 shows a tank 1 according to a first embodiment of the invention.

[0061] In this non-limiting example, the tank 1 is intended to equip a motor vehicle in order to supply it with fuel.

[0062] The tank 1 of Figure 1 has a generally ovoid shape extending along a longitudinal axis A1, parallel to D1, so as to have two longitudinal ends IA and IB. In this example, the tank 1 has a transverse dimension, in particular along D2, which varies along the axis A1. Starting from the longitudinal end IA, this transverse dimension increases up to a median longitudinal coordinate, then decreases down to the longitudinal end IB.

[0063] As an indication, the maximum transverse dimension of the tank 1 according to D2, which is located in this case at the level of said median longitudinal coordinate, can be approximately 500 mm.

[0064] The tank 1 comprises a body which in this example is provided with a jacket 2, a shell 3 and a reinforcement 4.

[0065] The jacket 2 forms an internal surface and an external surface defining a thickness of this jacket 2, which in this example is substantially constant in the different parts of the tank 1.

[0066] The internal surface of the jacket 2, which also forms an internal surface of the body of the tank 1, delimits a cavity 5 intended to contain a pressurized fluid constituting in this example said fuel.

[0067] In this example, cavity 5 is intended to contain a fluid, gas or liquid fuel, having a pressure of the order of 70 MPa.

[0068] The shell 3 also comprises an internal surface and an external surface defining a thickness of this shell 3, which in this example is substantially constant in the different parts of the tank 1.

[0069] Shell 3 forms an envelope of tank 1.

[0070] The inner surface of the shell 3 matches the outer surface of the jacket 2.

[0071] The jacket 2 and the shell 3 thus constitute a double-walled body and each have respective and complementary properties taking into account their respective material and manufacturing process (see further below).

[0072] In this example, the reinforcement 4 is configured to connect two parts of the body which are located opposite each other, these opposite parts forming two transverse ends of the body according to D2. The reinforcement 4 makes it possible to improve the mechanical resistance of the tank 1, taking into account in particular the pressures and depressions which it undergoes during its use.

[0073] The reinforcement 4 has a generally elongated shape along a direction D4, called the “connection direction”, which in this example is parallel to the direction D2 and which passes through said median longitudinal coordinate of the tank 1.

[0074] In the non-limiting example of figure 1, the reinforcement 4 comprises an external envelope 6, a tie rod 7 and two diffusers 8 (only one diffuser being visible in this figure).

[0075] The reinforcement 4 and its external envelope 6 comprise a central part 4A and end parts 4B and 4C respectively connected to said transverse ends of the body in the manner described further below.

[0076] In this example, the central part 4A of the envelope 6 of the reinforcement 4 has a generally cylindrical geometry defining an axis of symmetry which corresponds to the direction D4.

[0077] The end portions 4B and 4C have a flared geometry, in this case an increasing dimension from the respective end of the central portion 4A to which they are connected towards the corresponding portion of the jacket 2 to which they are connected.

[0078] The external envelope 6 of the reinforcement 4 defines, radially inside relative to the direction D4, a hollow space which passes through the jacket 2 of the body of the tank 1 in the direction D4 so as to open onto the external surface of this jacket 2.

[0079] The envelope 6 thus forms a wall which extends circumferentially around D4, forming an internal surface and an external surface which define a thickness of this wall.

[0080] The internal surface of the envelope 6 delimits said hollow space.

[0081] The outer surface of the envelope 6 is a circumferentially closed surface around the direction D4. In this example, the entirety of this outer surface delimits the cavity 5 of the tank 1 so that the cavity 5 extends all around the reinforcement 4.

[0082] The outer casing 6 of the reinforcement 4 thus forms a well which passes through the cavity 5. In this example, the outer casing 6 of the reinforcement 4 is made in one piece with the jacket 2, in this case with parts of the jacket 2 forming said transverse ends of the body, so as to form a continuous extension of material.

[0083] In a non-limiting manner, the casing 6 and the jacket 2 comprise a thermoplastic material, making it possible to provide a sealing function for the fluid contained in the cavity 5.

[0084] The external envelope 6 of the reinforcement 4 is in this example made from a part previously manufactured by machining, injection, rotational molding or even extrusion-blow molding.

[0085] In the present description, the subassembly comprising in continuity of material the jacket 2 and the external envelope 6 of the reinforcement 4 is called “membrane”.

[0086] In a non-limiting manner, the membrane can be obtained by crystallization or crosslinking of thermoplastic material consisting on the one hand of said prefabricated part and on the other hand of wall elements held in relation to each other using appropriate tooling, or more generally by implementing any shaping process of the rotational molding, blow molding, or other molding or casting technique, so as to create an assembly by adhesion of material elements.

[0087] There will now be described, with particular reference to figures 2 and 3, a method of assembling such a membrane (jacket 2 and external envelope 6 of the reinforcement 4) with the other elements of a reinforcement 4 and a shell 3 of a tank 1 according to the invention.

[0088] The shell 3 is first braided onto the membrane using a ply interlacing braiding process, with the membrane being used as a mandrel during braiding.

[0089] In this example, four layers are successively braided onto the mandrel.

[0090] Each of the layers comprises an assembly of fibers which in this example are carbon fibers and which are braided to form five plies.

[0091] Conventionally, depending on their arrangement in the assembly, the fibers are called "axial fibers" when they are arranged in a substantially linear manner and "bias fibers" when they are arranged so as to successively intersect other fibers.

[0092] Figure 3 schematically shows a sectional view of a portion of a layer C1 of the shell 3, in which the assembled plies P1-P5 define a thickness of the layer C1 in a direction D5. Each of the plies P1-P5 comprises a series of axial fibers 21, also called "longis", which are spaced from each other in a direction D6 perpendicular to the direction D5 and to a direction D7 along which they extend. The axial fibers 21 specifically increase the mechanical strength of the layer C1 in the direction D7, making it possible in particular to reduce the deformations of the shell 3 in this direction.

[0093] Layer C1 of Figure 3 comprises ten bias fibers braided on the axial fibers 21, including two external bias fibers 22 and eight binding bias fibers 23-30.

[0094] One of the external bias fibers 22 is braided around the axial fibers 21 of the ply PI. The other external bias fiber 22 is braided around the axial fibers 21 of the ply P5. The external bias fibers 22 make it possible to smooth the external surfaces of the layer C1.

[0095] The binding bias fibers 23-30 are braided to connect the plies PI to P5 to each other.

[0096] More specifically, the binding bias fibers 23 and 24 connect the plies P1 and P2 to each other, the binding bias fibers 25 and 26 connect the plies P2 and P3 to each other, the binding bias fibers 27 and 28 connect the plies P3 and P4 to each other, and the binding bias fibers 29 and 30 connect the plies P4 and P5 to each other.

[0097] Thus, the binding bias fibers 23-30 are braided so as to each connect two respective adjacent plies, for example plies P1 and P2, so that two non-adjacent plies of layer C1, for example plies P1 and P3, are not connected to each other directly, but indirectly via in this example ply P2.

[0098] In this example, the binding bias fibers 24, 26, 28 and 30 are braided so as to evolve along parallel curves in the directions D5 and D6 and in phase opposition with respect to the binding bias fibers 23, 25, 27 and 29 (see figure 3). The different layers of the shell 3 can be braided in a similar manner, preferably by modifying the relative orientation of the axial fibers 21 from one layer to another, so as to provide the shell 3 with improved mechanical strength in several directions of space.

[0099] The shell 3 thus forms a fibrous texture which can be essentially made up of continuous interwoven fibers.

[0100] Of course, the number of layers of the shell 3 and / or the number of plies per layer and / or the number of plies directly connected to each other by binding bias fibers can be modified depending on the desired mechanical properties. Similarly, other technical fibers can be used to braid the shell 3, for example glass, basalt, aramid, linen, hemp fibers or even mixed fibers comprising for example polyamide or polyethylene filaments. The braiding of the shell 3 can also be carried out using a combination of such technical fibers and thermoplastic filaments.

[0101] Such a braiding process makes it possible to deposit layers of dry material in the form of several plies of fibers interwoven with each other, one by one or two by two or more depending on the needs. This operation can be reproduced several times, by stacking layers, in the same direction or in different directions in order to ensure a good canvas of textures capable of responding to the pressure forces generated by the fluid on the shell 3 of the tank 1.

[0102] Such a braiding process allows the deposited fibers to be shaped into the required shapes without fiber distortion and provides considerably improved properties in terms of tenacity, particularly in comparison with filament winding.

[0103] After braiding the shell 3 on the mandrel formed by said membrane, that is to say by the jacket 2 and by the external envelope 6 of the reinforcement 4, the hollow space constituted by this external envelope 6 is covered by the shell 3.

[0104] To open this hollow space towards the outside of the body formed by the jacket 2 and the shell 3, openings can be made in the shell 3 by separating the fibers which constitute it using a tool such as a conical point, so as not to cut the fibers and allow the shell 3 to retain its mechanical properties.

[0105] With reference to Figure 2, which illustrates an example in which the reinforcement 4 comprises only the outer casing 6 and the tie rod α, the prefabricated tie rod β is inserted into the hollow space formed by the outer casing 6 of the reinforcement 4 through one of the openings thus made in the shell 3. A tool comprising a mold 31, metallic or composite, and an axis 32 is then pre-positioned, by introducing the axis 32 through an opening made in the tie rod 7 and passages provided in the mold 31.

[0106] The mold 31 is then moved so as to come to bear on the external surface of the shell 3, by tightening nuts 33 cooperating with the axis 32, causing a folding of ends 9 of the tie rod ? against parts 10 of the shell 3 which delimit said openings formed by separation of fibers.

[0107] In this example, the parts 10 of the shell 3 are thus sandwiched between the tie rod 7 and the membrane formed by the jacket 2 and the external envelope 6 of the reinforcement 4, ensuring a robust mechanical connection between the reinforcement 4 and the body of the tank 1.

[0108] In this embodiment, this assembly is then consolidated by injecting a thermosetting resin via orifices (not shown) made in the tooling, after forming a vacuum in the space delimited by the mold 31 and the membrane integrating the jacket 2 which provides a counter-mold function.

[0109] In this example, the injection is carried out using a process known as “Vacuum-Assisted Resin Transfer Molding” (VARTM).

[0110] The assembly is then subjected to heat treatment in order to stiffen the resin.

[0111] The thermosetting resin can be replaced by a thermoplastic resin, in particular a low viscosity one allowing injection into the fibrous texture of the shell 3, or by a bio-sourced resin.

[0112] Alternative consolidation processes can be implemented, for example the process known under the Anglo-Saxon name “Resin Transfer Molding” (RTM) or an infusion process, or even consolidation by thermocompression for example when the shell 3 and / or the tie rod (see below) comprise a mixture of technical fibers and thermoplastic matrix filaments.

[0113] In this example, the tie rod is made by lightweight braiding of carbon fibers arranged mainly longitudinally / unidirectionally.

[0114] In other words, the majority of the fibers forming the tie rod ? extend substantially in the same direction which corresponds to the connection direction D4 when the tie rod 7 is assembled with the other parts of the tank 1.

[0115] Such an assembly of fibers allows the tie rod 7 and consequently the reinforcement 4 to oppose tensile forces exerted on the reinforcement 4 under the action of the pressure of the fluid carried into the cavity 5.

[0116] Of course, other technical fibers or different combinations of fibers can be used to form the tie rod 7, including for example glass fibers.

[0117] Figure 4 shows a tool similar to that of Figure 2 which is specifically adapted to the assembly of a reinforcement 4 with a tank body 1 having parts connected by the reinforcement 4 which are inclined relative to the connection direction D4. The preceding description applies by analogy to this embodiment.

[0118] The tooling of Figure 4 is distinguished in particular from that of Figure 2 in that it comprises heads 41 forming molds, centered on the axis 32 in openings of the mold 31. The heads 41 are arranged at the ends of the tie rod 7 so as to conform these ends when they are folded against the shell 3. By way of comparison, in the example of Figure 2, the geometry of the folded ends of the tie rod 7 results from the shape of the molds 31 themselves.

[0119] The preceding description also applies by analogy to the embodiment of Figure 5 which is essentially distinguished from that of Figure 2 in that the reinforcement 4 also comprises diffusers 8 and nuts 51.

[0120] The diffusers 8 are here rigid rings comprising for example a reinforced thermoplastic material each sandwiched between a respective one of the end parts of the external casing 6 of the reinforcement 4 and the shell 3 after folding down the ends 9 of the tie rod 7.

[0121] Such diffusers 8 make it possible to improve the distribution of loads on the hull 3, in particular when the ends 9 of the tie rod 7 are folded down.

[0122] The nuts 51 are also rigid rings which may comprise a reinforced thermoplastic material and which in this example have an ogive shape. The nuts 51 are arranged in end portions of the tie rod 7 so as to be axially retained in the direction D4 by the folded ends 9 of the tie rod 7.

[0123] In this example, the tooling and the tie rod 7 are in fact configured so that, when the ends 9 of the tie rod 7 are folded down, a radially internal part of these ends 9 comes to bear on the nuts 51 and a radially external part of the ends 9 comes to bear on the shell 3 (see figure 5).

[0124] The nuts 51 are configured to work in compression, so as to perform an anti-striction function capable of reducing the phenomena of sliding of the ends of the reinforcement 4 relative to the shell 3.

[0125] Such anti-restriction nuts 51 are particularly useful for tanks 1 intended to contain a fluid under high or very high pressure, such as hydrogen.

[0126] In a non-limiting manner, the diffusers 8 and the nuts 51 may comprise materials of the polyurethane, polyamide or even polyethylene type, and be reinforced with glass, carbon or other fibers.

[0127] Referring again to the embodiment of Figure 1, the reinforcement 4 of the reservoir 1 is in this case similar to that illustrated in Figure 5, the anti-striction nuts 51 not being shown in Figure 1.

[0128] The tank 1 of figure 1 further comprises a filling nozzle 61 integrated into the texture of the shell 3 at the longitudinal end IA of this tank 1.

[0129] The end piece 61 is configured to establish fluid communication between the cavity 5 and the outside of the tank 1, for the purpose of filling it or drawing off the fluid it contains. It follows from the preceding description that the invention makes it possible to produce a composite tank 1, in this case having a body formed of an internal jacket 2 impervious to the transported fluid and a braided shell 3, both monolithic, capable of withstanding very high pressures while considerably improving the aspects of fatigue, aging and explosion safety. In particular, depending on the geometry of the tank 1, one or more reinforcements similar to the reinforcement 4 described above make it possible to significantly reduce the deformations of the body and to design a tank 1 of varied shape, conformable to the location reserved for its installation in a vehicle. A tank 1 according to the invention makes it possible in particular to withstand pressures of several tens of MPa.

[0130] In particular, Figure 1 shows a tank 1 of ovoid shape comprising a single reinforcement 4.

[0131] Figures 6 to 8 show other examples of heteromorphic tanks 1 in accordance with the invention, which can be manufactured according to the same principles as those which have just been described.

[0132] Tank 1 of Figure 6 is described below only in terms of its differences from tank 1 of Figure 1, it being understood that the preceding description applies by analogy.

[0133] In the example of Figure 6, the body of the tank 1 has a generally flattened shape, in this case a dimension along the direction D2, or height, relatively small compared to its dimensions along DI and D3.

[0134] As an indication, the height according to D2 of tank 1 can be approximately 100 mm.

[0135] The jacket 2 and the shell 3 of the body define different parts 101-103 which define the shape of the tank 1. The parts 101 and 102 have a generally planar shape defining a lower wall 101 and an upper wall 102 of the body which extend parallel, facing each other. The parts 103 form side walls connecting the walls 101 and 102 so as to form rounded edges of the tank 1. The tank 1 comprises in this example a series of reinforcements 4 as described above and which are each configured to connect the parts 101 and 102 of the body to each other.

[0136] The reinforcements 4 are distributed in the tank 1, being spaced two by two at a substantially constant distance along the direction DI and along the direction D3.

[0137] Of course, the geometry, position and number of reinforcements 4 can be modified without departing from the scope of the invention, depending on the distribution of forces in the tank 1 during its use, which depends in particular on the geometry of the body.

[0138] Figure 7 shows another example of a tank 1 according to the invention which is described below only according to its differences from the tank 1 of Figure 6, the preceding description applying by analogy.

[0139] Tank 1 in Figure 7 has a dimension in direction D2 relatively greater than the height of the tank in Figure 6.

[0140] The upper part of the body comprises several upper walls 104-108 facing the lower wall 101 as well as two transverse walls 109.

[0141] The upper walls 104, 106 and 108 are parallel to the lower wall 101 while the upper walls 105 and 107 are inclined relative to the walls 104, 106 and 108 so as to create a bulge in the tank 1 at its central longitudinal part.

[0142] As an indication, the maximum height of the tank 1, i.e. the distance along D2 between the lower wall 101 and the upper wall 106, may be approximately 150 mm.

[0143] Concerning said transverse walls 109, only one of which is visible in Figure 7, these are parallel to the directions DI and D2 and are distant from each other in the direction D3 so as to define a constant width of the tank 1.

[0144] The reinforcements 4 comprise, on the one hand, reinforcements 121 similar to those of the tank of Figure 6, that is to say reinforcements 121 connecting the lower wall 101 and the upper part of the body to each other. The reinforcements 4 also comprise reinforcements 122 which connect the transverse walls 109 of the body to each other and which in this case have a connection direction perpendicular to these walls 109 and to the connection direction of the reinforcements 121. The reinforcements 4 of the tank 1 of Figure 7 thus extend by intersecting in two different directions in space, in this case D2 and D3, forming a biaxial network of reinforcements 4.

[0145] Figure 8 shows another example of a tank 1 according to the invention which is described below only according to its differences from the tank 1 of Figure 7, the preceding description applying by analogy.

[0146] The upper part of the body comprises two upper walls 131 and 132 facing the lower wall 101, two lower longitudinal walls 133 and two upper longitudinal walls 134.

[0147] The upper walls 131 and 132 are parallel to the lower wall 101.

[0148] The distance along D2 between the lower wall 101 and the upper wall 131 is greater than the distance along D2 between the lower wall 101 and the upper wall 132, forming a stepped reservoir.

[0149] As an indication, the maximum height of the tank 1, i.e. the distance along D2 between the lower wall 101 and the upper wall 131, may be approximately 400 mm.

[0150] The lower longitudinal walls 133, only one of which is visible in FIG. 8, are substantially parallel to the directions D2 and D3 and are spaced apart from each other in the direction DI so as to define a length of the tank 1.

[0151] One of the upper longitudinal walls 134 provides the connection between one of the lower longitudinal walls 133 and the upper wall 131, while the other upper longitudinal wall (not visible in figure s) provides the connection between the upper wall 131 and the upper wall 132.

[0152] The upper longitudinal walls 134 are opposite each other and extend along a plane slightly oblique to the plane D2-D3.

[0153] The reinforcements 4 comprise reinforcements 121 similar to the reinforcements 121 of the tank of Figure 7, that is to say reinforcements 121 connecting the lower wall 101 and the upper part of the body to each other, as well as reinforcements 122 similar to the reinforcements 122 of the tank of Figure 7, connecting the transverse walls 109 of the body to each other. The reinforcements 4 also comprise reinforcements 123, some of which connect the two lower longitudinal walls 133 to each other and others connect the two upper longitudinal walls 134 to each other.

[0154] The reinforcements 4 of the tank 1 of figure 8 thus extend by intersecting in three different directions of space, in this case DI, D2 and D3, forming a tri-axial network of reinforcements 4.

[0155] It results from these various non-limiting examples that the invention makes it possible to create polymorphic tanks which can comprise a network of multi-axial / multidirectional reinforcements.

[0156] Many variations can be made to these embodiments. For example, concerning the shell 3, it can comprise a peripheral layer comprising interlacings of metal filaments such as copper, in order to protect the tank 1 against electrostatic charges.

[0157] In one embodiment, the tank 1 may comprise a dimensional control device formed by an interlacing of optical, inductive or laser-charged filaments allowing the detection of defects or failures generated during the life of the tank 1.

[0158] In one embodiment, certain wells formed during the production of the membrane can be used not to provide additional reinforcements but to fix the tank 1 to a vehicle, for example using fixing studs passing through these wells.

[0159] Furthermore, the jacket 2 and / or the external envelope 6 of the reinforcement(s) 4 may be devoid of fibers, which makes it possible to reduce the cost, or on the contrary include fibers, for example to improve the adhesion of these elements.

[0160] The geometries described above and shown in the figures are in no way limiting. In addition to the polymorphic and heteromorphic geometry of the body of the tank 1, the possible reinforcement(s) 4 and / or their external envelope 6 may have a circular, oval, square, hexagonal or other section. Of course, a tank according to the invention may be used in a transport device other than a motor vehicle, for example in an aircraft or in a railway or naval vehicle.

Claims

Claims 1. Tank (1) for a transport device such as a motor vehicle, an aircraft or a boat, comprising a body which delimits a cavity (5) intended to contain a fluid, the body comprising a shell (3) forming an envelope of the tank (1), characterized in that the shell (3) comprises an assembly of fibers (21-30) forming one or more layers each having several folds (P1-P5) linked together by some of said fibers, called “binding bias fibers” (23-30).

2. Tank (1) according to claim 1, in which each of the layers comprises a number NI of plies (P1-P5) greater than two, the binding bias fibers (23-30) passing through a number N2 of plies (P1-P5) at least equal to two, NI being for example equal to five, N2 being for example equal to two for at least some of the binding bias fibers (23-30).

3. Tank (1) according to claim 1 or 2, wherein the body comprises a jacket (2) defining an internal surface which delimits the cavity (5) and an external surface matching an internal surface of the shell (3).

4. Tank (1) according to claim 3, in which the jacket (2) comprises a material such as plastic capable of making the jacket (2) tight to the fluid contained in the cavity (5).

5. Tank (1) according to any one of claims 1 to 4, comprising one or more reinforcements (4) which each connect to each other parts of the body arranged opposite each other.

6. Tank (1) according to claim 5 incorporating the characteristics of claim 3 or 4, in which each of the reinforcements (4) comprises a wall (6) made in one piece with the jacket (2).

7. Tank (1) according to claim 6, wherein each of the reinforcements (4) extends along a connecting direction (D4) and comprises a tie rod (7) housed in a hollow space formed by said wall (6) of the reinforcement (4), the tie rod (7) comprising one or more layers made of fibers, the majority of which extends along the connecting direction (D4).

8. Method of manufacturing a tank (1) according to any one of claims 1 to 7, comprising a step of braiding the fibers (21-30) with interlacing of folds (P1-P5) so as to form the shell (3).

9. Method according to claim 5 for manufacturing a tank (1) comprising the characteristics of claim 3, in which the braiding is carried out on the jacket (2) used as a mandrel.

10. Method according to claim 8 or 9 for manufacturing a tank (1) comprising the characteristics of claim 7, comprising for each of the reinforcements (4) a step of manufacturing the tie rod (7) by braiding the fibers forming this tie rod (7) and a step of inserting the tie rod (7) into the hollow space formed by said wall (6) of the reinforcement (4).

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