Method for producing polymorphic tanks

Abstract

The invention relates to a method for producing a tank (1) for a transport device such as a motor vehicle, an aircraft or a boat, the tank (1) comprising a body which defines a cavity (4) intended to contain a fluid, in particular a gas, the body comprising walls (5-7) forming a casing (2) of the tank (1) and one or more reinforcements (3), each of the reinforcements (3) connecting one of the walls to the other two (5, 6) arranged facing one another.

Description

[0001] Description

[0002] Title: Manufacturing processes for polymorphic tanks

[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 gas as fuel.

[0006] State of the prior art

[0007] In the transportation sector, using gas as fuel helps reduce greenhouse gas emissions.

[0008] Given the limited space available for fuel storage in contemporary and future transport devices, one solution is to use not a single tank as large as possible but several small tanks.

[0009] The use of several small-sized tanks makes it possible, in particular, to reduce the mechanical stresses exerted by the fluid stored on the tanks, and therefore to reduce the thickness of their shell.

[0010] However, there is a need to increase the useful fluid storage volume taking into account the space actually available to place the tank(s).

[0011] Statement of the invention

[0012] The invention aims to provide a solution for storing a fluid under pressure by maximizing the useful storage volume while reducing the risks resulting from the pressure exerted by the fluid thus stored.

[0013] To this end, the subject of the invention is a method of manufacturing a tank comprising a body which delimits a cavity intended to contain a fluid, in particular a gas, the body comprising walls forming an envelope of the tank and one or more reinforcements each connecting two of said walls arranged opposite each other, each of the reinforcements comprising a first end portion secured to one of said walls, a second end portion secured to the other of said walls and a central portion extending between the first end portion and the second end portion.

[0014] The method of the invention uses a tool comprising a mold and wellheads and comprises: holding a part, intended to form one of said reinforcements, between two shells of the mold, a shaping step comprising: o an arrangement of wall elements, intended to form said envelope, on surfaces of said shells, o an arrangement of material elements, intended to form said first end portion and said second end portion of the reinforcement, on support zones formed by said wellheads, a step of assembling said wall elements, said material elements and said part so as to form a continuous extension of material between the envelope and the reinforcement(s).

[0015] In one embodiment, the arrangement of said wall elements on the surfaces of the mold shells is carried out using a molding, casting or blowing technique.

[0016] In one embodiment, the arrangement of said wall elements on the surfaces of the mold shells comprises a deposition of several layers of the material forming the wall elements.

[0017] In one embodiment, the wall elements and / or said part comprise a thermoplastic material.

[0018] In one embodiment, said part is manufactured before implementing the assembly step, for example by machining, injection, rotational molding or extrusion blow molding. According to an alternative embodiment, said material elements intended to form the first end portion and the second end portion of the reinforcement are formed by said part.

[0019] In the context of this variant, the assembly step can be carried out so that said material elements intended to form the first end part and the second end part of the reinforcement are connected substantially tangentially to said wall elements.

[0020] According to another embodiment variant, said material elements intended to form the first end part and the second end part of the reinforcement are formed by said wall elements.

[0021] In the context of this variant, the assembly step can be carried out so that said material elements intended to form the first end part and the second end part of the reinforcement are connected substantially tangentially to said part.

[0022] The invention can be implemented to manufacture a tank for a transport device such as a motor vehicle, an aircraft or a boat,

[0023] The bulk of the tank, that is to say the total volume it occupies in space, is mainly determined by the geometry of its envelope and therefore by the geometry of the said walls, which designate different parts of the envelope which together can constitute a single, monolithic piece. In particular and cleverly, the reinforcements can remain completely contained within this volume.

[0024] According to the proposed arrangement, the reinforcements occupy a space in the tank that could constitute an additional part of the fluid storage cavity. However, such an arrangement of the reinforcements makes it possible to improve the mechanical strength of the shell and to confer the required mechanical properties to the tank, the shell of which can have a very wide variety of geometries.

[0025] The invention thus makes it possible to produce a polymorphic tank, optimizing the fluid storage volume formed by the cavity taking into account the space actually available in the vehicle it is intended to equip. This storage volume can thus be greater than that which would be constituted by a conventional cylindrical tank, or by an assembly of conventional tanks and makes it possible to eliminate the connections between tanks as well as the risks associated with such an assembly.

[0026] Depending on the shape of the space available for the tank, the latter may comprise a relatively simple geometry, for example a generally parallelepiped shape or other elementary shapes, or comprise several parts, at least some of which have a relatively simple geometry. The tank may also comprise parts of a more complex shape, for example by defining convex or concave walls or surfaces and / or walls or surfaces respectively oriented in different directions of the space.

[0027] The reinforcements make it possible to join together different parts of the envelope, in this case the walls that they connect, in order to locally reinforce the mechanical resistance of the tank.

[0028] The invention thus makes it possible to improve the compactness, storage volume and mechanical resistance of the tank.

[0029] The invention makes it possible to manufacture such a tank in which the reinforcements are integral with the casing, that is to say in which the reinforcements form a continuous extension of material with the casing, in particular with the walls which they connect.

[0030] Generally, each of the reinforcements can have a connection direction along which it extends.

[0031] The direction of connection of each of the reinforcements may be perpendicular or oblique to one and / or the other of the first walls which are connected to each other by this reinforcement.

[0032] By way of non-limiting example, in the case of a reinforcement connecting two walls parallel to each other, the direction of connection of this reinforcement may be perpendicular to each of these walls. In the case of a reinforcement connecting two walls oblique to each other, the direction of connection of this reinforcement may be perpendicular to one of these walls and oblique to the other of these walls.

[0033] In one embodiment, each of the reinforcements, or at least one of them, forms a circumferentially closed outer surface around the bonding direction.

[0034] Preferably, the entirety of this external surface, or at least a portion of it, delimits the cavity.

[0035] In one embodiment, each of the reinforcements, or at least one of them, forms an internal surface delimiting a hollow space.

[0036] Preferably, this hollow space defines an opening which passes through the tank in the connection direction.

[0037] In other words, a given reinforcement can be formed by a wall which forms a solid of revolution or more generally by a solid closed around the direction of connection which it constitutes.

[0038] 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.

[0039] A tank comprising reinforcements forming such hollow spaces can thus form a honeycomb structure, the envelope delimiting a volume comprising the fluid storage cavity crossed by cells formed by the hollow spaces of the reinforcements.

[0040] A reinforcement provided with such a hollow space makes it possible to fulfil its mechanical strength function, to reduce the mass of the tank and, when the hollow space forms an opening passing through the tank, to constitute empty spaces in which additional elements such as tank fixing elements can be housed.

[0041] In one embodiment, the connection direction of one or more of said reinforcements is perpendicular or oblique to the connection direction of one or more other of said reinforcements. In particular, in a non-limiting manner, certain reinforcements may connect together two walls of the tank which extend, for example, parallel to a first reference direction, while other reinforcements may connect together two walls of the tank which extend in this example parallel to a second reference direction which is oblique or perpendicular to the first reference direction.

[0042] In one embodiment, each of the reinforcements, or at least one of them, comprises a first end portion secured to one of said walls that it connects, a second end portion secured to the other of said walls that it connects and a central portion extending between the first end portion and the second end portion.

[0043] By way of non-limiting example, the central part may have a tubular geometry.

[0044] The first end portion and / or the second end portion may each have an increasing dimension going from the central portion towards the first wall to which it is respectively connected.

[0045] Such geometry of the end parts makes it possible to reduce the shear stresses introduced by the internal pressure of the tank.

[0046] Preferably, the walls and / or reinforcements comprise a material chosen from thermoplastics, such as polyethylene, polyamide, polyurethane, thermosets, and bio-sourced resins.

[0047] Among other advantages of these materials, thermoplastic in particular makes it possible to give the body of the tank properties of flexibility and resistance.

[0048] In one embodiment, the tank body is fabricated as a single piece.

[0049] Alternatively, the tank body can be manufactured by assembling several previously manufactured parts.

[0050] Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows.

[0051] Brief description of the drawings

[0052] The following detailed description refers to the appended drawings in which: [Fig. 1] is a schematic perspective view, partially broken away, of a tank according to a first embodiment of the invention, the tank comprising reinforcements oriented in a single direction, forming a mono-axial reinforcement network;

[0053] [Fig. 2] is a partial schematic perspective view of a tank similar to that of Fig. 1, showing four adjacent reinforcements;

[0054] [Fig. 3] is a schematic perspective view, partially cut away, of a tank according to a second embodiment of the invention, the tank comprising reinforcements oriented in two mutually orthogonal directions, forming a biaxial reinforcement network;

[0055] [Fig. 4] is a schematic perspective view, partially cut away, of a tank according to a third embodiment of the invention, the tank comprising reinforcements oriented in three mutually orthogonal directions, forming a tri-axial reinforcement network;

[0056] [Fig. 5] is a partial schematic sectional view of manufacturing elements of a tank according to a first embodiment of the invention;

[0057] [Fig. 6] is a partial schematic sectional view of manufacturing elements of a tank according to a second embodiment of the invention;

[0058] [Fig. 7] is a partial schematic sectional view of manufacturing elements of a tank according to a third embodiment of the invention.

[0059] Detailed description of embodiments

[0060] Figures 1 to 4 include a reference frame defining three mutually orthogonal directions DI, D2 and D3. In this example, DI is a longitudinal direction, D2 a vertical direction and D3 a transverse direction.

[0061] Figure 1 shows a tank 1 according to a first embodiment of the invention.

[0062] In this non-limiting example, the tank 1 is intended to equip a motor vehicle in order to supply it with fuel. With reference to Figure 1, the tank 1 has a generally flattened shape, in this case a dimension in the vertical direction D2, or height, relatively small compared to its longitudinal and transverse dimensions, that is to say in the directions DI and D3 respectively.

[0063] As an indication, the height according to D2 of tank 1 can be approximately 100 mm.

[0064] The dimension of the tank 1 along the transverse direction D3, or width, varies along the direction D1. Starting from the longitudinal end located towards the left and bottom of Figure 1, the width increases up to a first longitudinal coordinate, remains constant up to a second longitudinal coordinate and then decreases to the opposite longitudinal end, located towards the right and top of Figure 1.

[0065] In this example, the tank 1 comprises a body forming an envelope 2, also called a “shell”, as well as reinforcements 3.

[0066] The envelope 2 delimits the external contours of a cavity 4 intended to contain a pressurized fluid which constitutes in this example said fuel.

[0067] In this example, cavity 4 is intended to contain a fluid, gas or liquid, having a pressure of the order of 300 MPa.

[0068] The envelope 2 is formed of different walls 5-7, also called “skins”, which in this example are made from a single piece (see further below), so as to form a monolithic shell.

[0069] With reference to Figure 1, the envelope 2 more precisely comprises a lower wall 5, an upper wall 6 and side walls 7.

[0070] The lower wall 5 and the upper wall 6 are spaced apart from each other in the direction D2 so as to define, on the one hand, the height of the reservoir 1, which corresponds to the distance along D2 between an external surface of the lower wall 5 and an external surface of the upper wall 6 and, on the other hand, a height of the cavity 4 which corresponds to the distance along D2 between an internal surface of the lower wall 5 and an internal surface of the upper wall 6. In this example, the walls 5 and 6 are parallel, facing each other, and the side walls 7 connect the walls 5 and 6 to each other so as to form rounded edges of the reservoir 1.

[0071] The tank 1 also comprises a filling member 8 having in this example a tubular geometry and being integral with one of the side walls 7.

[0072] The member 8 is configured to establish fluid communication between the cavity 4 and the exterior of the reservoir 1, with a view to filling it or drawing off the fluid it contains.

[0073] In this example, the reinforcements 3 are configured to connect the walls 5 and 6 to each other, so as to reinforce the mechanical resistance of the casing 2 and therefore of the tank 1, taking into account in particular the pressures and depressions to which it is subjected during use.

[0074] With reference to Figure 2 which shows a part of a tank 1 similar to that of Figure 1, each of the reinforcements 3 has a generally elongated shape along a direction D4, called the “connection direction”. In this example, the connection direction D4 of each of the reinforcements 3 is substantially parallel to the vertical direction DI and therefore substantially perpendicular to the walls 5 and 6.

[0075] The geometry of a reinforcement 3 will now be described with reference to the second reinforcement 3 starting from the right of figure 2.

[0076] The reinforcement 3 comprises a central part 11, a lower end part 12 connected to the wall 5 and an upper end part 13 connected to the wall 6.

[0077] The central part 11 has a cylindrical geometry and has an axis of symmetry which corresponds to the direction D4.

[0078] The lower end portion 12 has a flared geometry, in this case an increasing dimension from the end of the central portion 11 to which it is connected towards the wall 5. Similarly, the upper end portion 13 also has a flared geometry having an increasing dimension from the end of the central portion 11 to which it is connected towards the wall 6. In this example, the central portion 11 and the end portions 12 and 13 define radially inside relative to the direction D4 a hollow space 14 which passes through the tank 1 in the direction D4 (visible in FIG. 1).

[0079] The wall formed by these different parts 11, 12 and 13 of the reinforcement 3 thus extends circumferentially around the connection direction D4, defining an internal surface and an external surface.

[0080] The internal surface of the reinforcement 3 delimits said hollow space 14. In this example, this internal surface of the reinforcement 3 is connected to, or opens onto, the external surface of the walls 5 and 6.

[0081] The external surface of the reinforcement 3 is a circumferentially closed surface around the direction D4 and the entirety of this external surface delimits the cavity 4 of the tank 1. In other words, the cavity 4 extends all around the reinforcement 3.

[0082] In this example, reinforcement 3 thus forms a well which crosses cavity 4.

[0083] The other reinforcements 3 shown in Figure 2, as well as each of the reinforcements 3 of the tank 1 of Figure 1 are similar to the reinforcement 3 which has just been described.

[0084] With reference to Figure 1, the reinforcements 3 are distributed over the entire length and width of the tank 1, being spaced two by two by a substantially constant distance along the direction DI and along the direction D3.

[0085] Of course, the geometry, position and number of reinforcements 3 can be modified without departing from the scope of the invention, depending on the distribution of forces in the tank 2 during its use, which depends in particular on the geometry of the casing 2.

[0086] In this example, the envelope 2 and the reinforcements 3 comprise a thermoplastic material.

[0087] Each of the reinforcements 3 of Figure 1 is also integral with the casing 2, more precisely with the walls 5 and 6, so as to form a continuous extension of material. Optionally, the casing 2 and / or the reinforcements 3 may also include technical fillers or fibers in order to increase resistance to pressure forces generated by the fluid. In a non-limiting manner, the thermoplastic matrix may be reinforced by mineral or fibrous fillers, by glass, carbon, aramid, basalt filaments, or even by plant fibers, so as to produce a fibrous texture. Such fillers or fibers may be integrated into the thermoplastic matrix, for example by weaving, braiding, rotational molding, blow molding or even by injection.

[0088] The reinforcements 3 and / or the envelope 2 may comprise an additive in order to improve adhesion with the selected base and / or be doped with adjuvants, for example in the form of nanoparticles, in order to reinforce the sealing properties, the mechanical strength and / or the pressure resistance of the tank 1.

[0089] Alternatively, the casing 2 and / or the reinforcements 3 can be manufactured by depositing, for example by rotational molding, several layers of different thermoplastic materials which, agglomerated with each other, ensure better sealing or mechanical properties.

[0090] Methods of manufacturing such a tank 1 are described further below by way of example.

[0091] Figure 3 shows a tank 1 according to a second embodiment which is described below only according to its differences from that of Figure 1. The preceding description applies by analogy to this second embodiment.

[0092] In this example, tank 1 has a dimension in direction D2 relatively larger than the height of the tank in Figure 1.

[0093] The upper part of the envelope 2 comprises several upper walls 61-65 facing the lower wall 5 as well as two transverse walls 71.

[0094] The upper walls 61, 63 and 65 are parallel to the lower wall s while the upper walls 62 and 64 are inclined relative to the walls 61, 63 and 65 so as to create a bulge in the reservoir 1 at its central longitudinal portion. In particular, the distance along D2 between the lower wall 5 and the upper wall 63 is greater than the distance along D2 between the lower wall 5 and the upper walls 61 and 65. The distance along D2 between the lower wall 5 and the upper wall 62 evolves monotonically along DI so as to make a transition between the upper walls 61 and 63. Similarly, the distance along D2 between the lower wall 5 and the upper wall 64 evolves monotonically along DI so as to make a transition between the upper walls 63 and 65.

[0095] As an indication, the maximum height of the tank 1, i.e. the distance along D2 between the lower wall 5 and the upper wall 63, can be approximately 150 mm.

[0096] Concerning said transverse walls 71, only one of which is visible in Figure 3, 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.

[0097] The reinforcements 3 comprise on the one hand reinforcements 31 similar to those of the tank of FIG. 1, that is to say reinforcements 31 connecting the lower wall 5 and the upper part of the casing 2 to each other. Thus, certain reinforcements 31, called "first reinforcements", connect the lower wall 5 and the upper wall 61 to each other, or the lower wall 5 and the upper wall 63, or the lower wall 5 and the upper wall 65. Other reinforcements 31, called "second reinforcements", connect the lower wall 5 and the upper wall 62 to each other, or the lower wall 5 and the upper wall 64.Taking into account the respective orientation of the walls 5 and 61-65, the first reinforcements 31 have a connection direction perpendicular to the walls 5, 61, 63 and 65 to which they are respectively connected, while the second reinforcements 31 have a connection direction perpendicular to the lower wall s and oblique relative to the upper walls 62 and 64 to which they are respectively connected.

[0098] The reinforcements 3 further comprise reinforcements 32 which connect the transverse walls 71 to each other and which in this case have a connection direction perpendicular to these walls 71 and to the connection direction of the reinforcements 31. The reinforcements 3 of the tank 1 of FIG. 3 thus extend by intersecting in two different directions in space, in this case D2 and D3, forming a biaxial network of reinforcements 3.

[0099] Figure 4 shows a tank 1 according to a third embodiment which is described below only according to its differences from that of Figure 3. The preceding description applies by analogy to this third embodiment.

[0100] The upper part of the envelope 2 comprises two upper walls 66 and 67 facing the lower wall s, two lower longitudinal walls 72 and two upper longitudinal walls 73.

[0101] The upper walls 66 and 67 are parallel to the lower wall 5.

[0102] The distance along D2 between the lower wall 5 and the upper wall 66 is greater than the distance along D2 between the lower wall 5 and the upper wall 67, forming a stepped reservoir.

[0103] As an indication, the maximum height of the tank 1, i.e. the distance along D2 between the lower wall 5 and the upper wall 66, can be approximately 150 mm.

[0104] The lower longitudinal walls 72, only one of which is visible in FIG. 4, 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.

[0105] One of the upper longitudinal walls 73 provides the connection between one of the lower longitudinal walls 72 and the upper wall 66, while the other upper longitudinal wall 73 (not visible in FIG. 4) provides the connection between the upper wall 66 and the upper wall 67.

[0106] The upper longitudinal walls 73 are opposite each other and extend along a plane slightly oblique to the plane D2-D3.

[0107] The reinforcements 3 comprise on the one hand reinforcements 31 similar to the reinforcements 31 of the tank of figure 3, that is to say reinforcements 31 connecting the lower wall 5 and the upper part of the casing 2 to each other. Thus, certain reinforcements 31 connect the lower wall 5 and the upper wall 66 to each other and other reinforcements 31 connect the lower wall 5 and the upper wall 67 to each other.

[0108] The reinforcements 3 also comprise reinforcements 32 similar to the reinforcements 32 of the tank in FIG. 3, connecting the transverse walls 71 of the casing 2 to each other.

[0109] In this embodiment, the reinforcements 3 also comprise reinforcements 33, some of which connect the two lower longitudinal walls 72 to each other and others of which connect the two upper longitudinal walls 73 to each other.

[0110] The reinforcements 3 of the tank 1 of figure 4 thus extend by intersecting in three different directions of space, in this case DI, D2 and D3, forming a tri-axial network of reinforcements 3.

[0111] The invention thus makes it possible to create polymorphic tanks which can include a network of multi-axial / multi-directional reinforcements.

[0112] Non-limiting examples of methods for manufacturing tanks in accordance with the invention will now be described.

[0113] Well-type reinforcements 3, for example those of the tank 1 of figure 1, can be manufactured in the manner described below with reference to figure 5 which shows a tool and elements of material intended to form one of the reinforcements 3 as well as the walls 5 and 6 of the casing 2.

[0114] Said material elements comprise on the one hand a part 101 comprising a central part 102 and two end parts 103 and 104 and, on the other hand, wall elements 105 and 106.

[0115] In this example, part 101 is prefabricated by machining, injection, rotational molding or even extrusion-blow molding.

[0116] The tooling comprises a mold provided with outer shells 111 and 112, wellheads 113 and 114, a centering axis 115 and a holding rod 116.

[0117] The outer shells 111 and 112 are arranged opposite each other and closed on each other so as to delimit an interior volume delimited by surfaces of the shells 111 and 112 on which said wall elements 105 and 106 are arranged using a rotational molding, blow molding or similar process.

[0118] The end portions 103 and 104 of the part 101 have a general shape that gradually widens as one approaches the respective wall elements 105 and 106 so as to allow their substantially tangential connection to these wall elements 105 and 106. The part 101 thus extends over the entire distance separating the wall elements 105 and 106.

[0119] The wall elements 105 and 106 are arranged so as to cover the ends of the part 101 to ensure effective anchoring. This solution is particularly preferred for high viscosity materials where the material has difficulty being injected even when hot.

[0120] In this example, the centering pin 115 has a cylindrical shape and may be solid or hollow. It is arranged in a fitted manner inside the part 101 so as to extend at the central portion 102. The centering pin 115 is fitted at its respective ends into the wellheads 113 and 114, which are themselves centered and held between the two shells 111 and 112 of the mold which comprise corresponding openings or passages for this purpose. The centering pin 115 thus constitutes a spacer between the wellheads 113 and 114.

[0121] In this example, the centering axis 115 helps to keep the wellheads 113 and 114 in abutment against opposite surfaces of the mold shells, the wellheads having a shoulder in abutment against these surfaces. The centering axis 115 is intended to hold the part 101 between the mold shells 111 and 112 prior to shaping and crystallization of the material of the wall elements 105 and 106. This axis 115 can be pierced radially to improve heat exchanges during the shaping process, which can be a rotational molding, extrusion blow molding or similar process.

[0122] Each of the wellheads 113 and 114 has a shape that gradually widens between the centering axis 115 and the corresponding shell 111, 112 of the mold to which it is connected. These wellheads extend the internal shape of the mold shells on which the material of the wall elements 105 and 106 will be deposited during the shaping process.

[0123] In this example, the wellheads 113 and 114 form cores along which the material will be deposited, and these wellheads hold the part 101 in position, centered on the axis A1 along which it extends. Alternatively, the wellheads 113 and 114 may serve essentially to hold the part 101 in position, centered on the axis A1, by constituting support zones for the part 101 in the end portions 103 and 104.

[0124] The holding rod 116 is designed to pass along the axis A1 of the part 101 through the shells 111 and 112, the wellheads 113 and 114, the centering axis 115, and the part 101. This holding rod 116 comprises clamping means at these ends, such as nuts screwed onto threaded parts, making it possible to keep the elements assembled together with appropriate tightening. This assembly using a holding rod 116 prevents any bending of the part 101 during the softening phase, allowing it to be mated with the material of the wall elements 105 and 106.

[0125] This non-limiting method thus comprises the following steps: placing and holding between the two wellheads 113 and 114 the centering axis 115 inside the part 101, this centering axis 115 being fitted onto the wellheads 113 and 114; placing and holding the shells 111 and 112 of the mold before closing these shells on each other, of the assembly formed by the centering axis 115, the part 101 and the wellheads 113 and 114; placing the holding rod 116 passing through the shells 111 and 112, the wellheads 113 and 114, the centering axis 115 and the part 101 via corresponding passages provided in each of these elements; final shaping of the material inside the mold, in order to produce the body of the tank.

[0126] After crystallization or crosslinking of the thermoplastic material, the mold is dismantled, the holding rod 116 is removed, the shells 111 and 112 of the mold are opened, the wellheads 113 and 114 are removed, as well as the centering axis 115. Then remain the envelope 2 formed by the wall elements 105 and 106 as well as the reinforcement formed by the part 101 made of the same material as the wall elements 105 and 106, the material of the end parts 103 and 104 forming a continuous extension with the material of the wall elements 105 and 106.

[0127] Of course, the method described above can be implemented to simultaneously produce several reinforcements 3.

[0128] Many variations can be made to this manufacturing process, for example that which is described below with reference to Figure 6 as distinguished from that of Figure 5. The preceding description applies by analogy.

[0129] In the example of Figure 6, the outer shells 111 and 112 of the mold and the wellheads 113 and 114 are configured so that the wellheads 113 and 114 are sandwiched between the centering axis 115 and, respectively, the outer shells 111 and 112.

[0130] The material elements intended to form the envelope and the reinforcement comprise, on the one hand, a prefabricated tubular part 121 and, on the other hand, wall elements 105 and 106 which comprise parts 122 and 123 intended to form said end parts of the reinforcement.

[0131] The end portions 122 and 123 have a general shape that is progressively restricted as one approaches the respective ends of the part 121 so as to allow their substantially tangential connection to this part 121.

[0132] This manufacturing variant can, for example, be used to manufacture a relatively long reinforcement or several reinforcements of variable length by varying the length of the part 121.

[0133] As is well known, the permissible length of the reinforcement depends on the material used and the processing conditions. For example, in rotational molding, the adjustment parameters include the rotation speed, the fluidity of the material or even the softening point of this material. Typically, the use of a thermoplastic such as HD 1000 polyethylene is suitable for manufacturing a 50 mm reinforcement in the manner described above.

[0134] Figure 7 illustrates a tool and material elements used in a manner analogous to that just described with reference to Figure 6, for the manufacture of reinforcements connecting to each other facing walls inclined relative to each other. The preceding description applies by analogy to the example of Figure 7.

[0135] According to the invention, the body of the tank 1, including the casing 2 and the reinforcements 3, can therefore be manufactured using a shaping process of the rotational molding or blow molding type, or any other molding or casting technique, so as to create an assembly by adhesion of material elements forming on the one hand walls of the casing and on the other hand the reinforcements. To do this, when the reinforcements form wells, the tooling can comprise members for holding the material elements intended to form the reinforcements, these members being housed in the parts forming these wells during molding. When the reinforcements are not hollow but solid, they can be positioned axially in the mold by fittings on pivots arranged in the mold.

[0136] The methods described above are suitable for the manufacture of tanks 1 comprising reinforcements 3 which have connection directions which are substantially parallel to each other, or slightly oblique to each other, forming a mono-axial network as illustrated in FIG. 1.

[0137] To manufacture a tank 1 provided with intersecting reinforcements 3 forming a multi-axial network of reinforcements, such as those illustrated in Figures 3 and 4, the outer mold may comprise different parts each having the pivots necessary for holding the well supports. Alternatively, the mold may comprise keys representative of each of the faces having the pivots for holding the wells, which keys may then be enclosed in an outer mold.

[0138] The invention is not limited to the embodiments and variants described above. In general, the invention makes it possible to produce polymorphic tanks, capable of conforming to available volumes, which makes it possible to increase the fluid carrying capacity and therefore the autonomy of the vehicles they equip. The invention thus makes it possible to produce tanks having a relatively complex geometry, or on the contrary a relatively simple or even conventional geometry, for example a tank with a cylindrical casing which may be intended for the aeronautical sector in order to store a large quantity of fuel. The geometry and structure of the reinforcements 3 may be different from those described above. For example, the end parts of the reinforcements may have a concave or other revolution shape. The central part of the reinforcements or all of their parts may have a square, hexagonal or other section.Furthermore, the reinforcements may be solid or include a filler material, unlike the well-type reinforcements described above.

[0139] The respective orientation of the reinforcements can also present numerous variations, whether in relation to one or more walls of the envelope to which they are connected or in relation to other reinforcements.

[0140] In terms of material, the envelope 2 and / or the reinforcements 3 may comprise another type of thermoplastic or another type of material, for example a thermosetting material or even a resin.

[0141] Of course, a tank according to the invention can be used in a transport device other than a motor vehicle, for example in an aircraft or in a railway or naval vehicle.

Claims

Demands 1. A method for manufacturing a tank (1) comprising a body that delimits a cavity (4) intended to contain a fluid, in particular a gas, the body comprising walls (5-7) forming a shell (2) of the tank (1) and one or more reinforcements (3) connecting each of two of said walls (5, 6) arranged opposite each other, each of the reinforcements (3) comprising a first end portion (12) integral with one of said walls (5), a second end portion (13) integral with the other of said walls (6), and a central portion (11) extending between the first end portion (12) and the second end portion (13), the method employing tooling comprising a mold and wellheads (113, 114) and comprising: a retainer for a part (101, 121), intended to form one of said reinforcements (3), between two shells (111, 112) of the mold, a shaping step comprising: o an arrangement of wall elements (105, 106),intended to form said casing (2), on surfaces of said shells (111, 112), or an arrangement of material elements (103, 104, 122, 123), intended to form said first end part (12) and said second end part (13) of the reinforcement (3), on bearing areas formed by said wellheads (113, 114), an assembly step of said wall elements (105, 106), of said material elements (103, 104, 122, 123) and of said part (101, 121) so as to form a continuous extension of material between the casing (2) and the reinforcement(s) (3).

2. Method according to claim 1, wherein the arrangement of said wall elements (105, 106) on the surfaces of the mold shells (111, 112) is carried out using a molding, casting or blow molding technique.

3. Method according to claim 1 or 2, wherein the arrangement of said wall elements (105, 106) on the surfaces of the mold shells (111, 112) comprises a deposit of several layers of the material forming the wall elements (105, 106).

4. A method according to any one of claims 1 to 3, wherein the wall elements (105, 106) and / or said part (101, 121) comprise a thermoplastic material.

5. A method according to any one of claims 1 to 4, wherein said part (101, 121) is manufactured before implementation of the assembly step, for example by machining, injection, rotomolding or extrusion blow molding.

6. A method according to any one of claims 1 to 5, wherein said material elements (103, 104) intended to form the first end part (12) and the second end part (13) of the reinforcement (3) are formed by said part (101).

7. Method according to claim 6, wherein the assembly step is carried out so that said material elements (103, 104) intended to form the first end part (12) and the second end part (13) of the reinforcement (3) are connected in a substantially tangential manner to said wall elements (105, 106).

8. A method according to any one of claims 1 to 5, wherein said material elements (122, 123) intended to form the first end part (12) and the second end part (13) of the reinforcement (3) are formed by said wall elements (105, 106).

9. Method according to claim 8, wherein the assembly step is carried out so that said material elements (122, 123) intended to form the first end part (12) and the second end part (13) of the reinforcement (3) are connected in a substantially tangential manner to said part (121).

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