DE102021111561A1 - Hydrogen flat high-pressure tank for mobile and stationary applications, as well as method for manufacturing the hydrogen flat high-pressure tank - Google Patents

Abstract

A flat, high-pressure hydrogen tank (1) can be used for a means of transport (100), in particular for a car, bus, truck, tractor, train or airplane, or for a stationary application such as a building. There is a top wall (2), a bottom wall (3), a front wall (4), a back wall (5), a left wall (6) and a right wall (7) which define a storage space (8th ) delimit. A valve arrangement (10) with at least one valve (11, 12) is provided and designed to fill hydrogen under pressure into the storage space (8) and remove it from the storage space (8). At least one stringer (15) is provided and arranged within the storage space (8). At least one stringer (8) is fastened to two opposite walls (2, 3 or 4, 5 or 6,7) and can be subjected to tensile loads, which ensures the stability of the flat, high-pressure hydrogen tank (1) even at high internal pressure.

Description

The invention relates to a flat, high-pressure hydrogen tank for mobile and/or stationary applications, and to a method for producing the flat, high-pressure hydrogen tank.

In order to be able to achieve climate goals, alternative types of drive are essential. Battery-powered vehicles are (however) too heavy and too expensive and charging takes a long time even when special charging stations are available, which can irreversibly damage the battery if charged quickly. An alternative to this are hydrogen-powered vehicles, which convert the hydrogen into electrical energy and thermal energy using a fuel cell, for example, with which the vehicle can then be operated and heated.

One problem here is the storage of the hydrogen, which requires a large volume with a low specific weight. The gaseous hydrogen is stored in a tank under high pressure. Working pressures of 750 bar and filling pressures of 875 bar are achieved. With a safety factor S of 2.25, the tank must achieve a strength of 1688 bar. In order to be able to withstand such pressures, high demands are placed on the construction and design of the flat, high-pressure hydrogen tank with high-performance materials such as fiber composites. Until now, these tanks have been circular for technical gases with a cross-sectional area A = r^2*3.14, which, in contrast to the flat tank, limits the filling volume.

With a circular cross-section, the maximum filling volume is not available, as with a rectangular cross-section. When installed in a vehicle, additional safety retaining frames or retaining straps are often necessary, which leads to a further geometric loss of the filling volume of at least 21.5%. The retaining frames or retaining straps for the round tank require an additional space of between 0.6% and 19.5%. A flat tank has clear advantages here. Even with two round tanks arranged next to each other, there is a loss of installation space of up to a maximum of 41%. With X adjacent round tanks, for example 15 round tanks, as can be used on a bus roof, there is a loss of filling space of several 100% (up to > 600%) and thus a loss of travel range for means of transport. In the 13A until 13C such round tanks from the prior art are shown. In 13A the unused volume is shown in white. In 13B shows the unused volume between two tanks. 13C makes it clear that each bottle also requires its own connection, which is also very expensive given the very high number of bottles.

It is therefore the object of the present invention to create a flat, high-pressure hydrogen tank with the highest possible filling volume, which meets all stability requirements and acceptance criteria with a safety factor of S=2.25.

The object is achieved by the flat hydrogen high-pressure tank according to claim 1 and by the means of transport according to claims 19 and 20, as well as by the stationary application according to claim 21 and by the method for producing the flat hydrogen high-pressure tank according to claim 22. Claims 2 to 18 contain developments according to the invention of the flat, high-pressure hydrogen tank.

The hydrogen flat high-pressure tank according to the invention can be used advantageously both for mobile means of transport and for stationary applications. Mobile applications include means of transport of all kinds. In particular, these include cars, buses, trucks, tractors, trains, airplanes and ships. However, it is also very suitable for stationary applications, especially for use in a building or on a foundation. The building can be any building (eg residential building, factory, power station, etc.). The flat high-pressure hydrogen tank includes an upper wall, a lower wall, a front wall, a rear wall, a left wall, and a right wall. These then flat walls with a dished bottom in the edge areas together delimit a storage space. The terms for the walls are chosen for better differentiation. They do not specify any spatial position at the installation site. For example, there is a fittings system with valves, sensors and electrically controllable actuators, with at least one valve and designed to be able to determine the internal pressure of the hydrogen tank, the temperature and the fill level at any time in order to ensure that the storage space is uninterrupted, when filling, during the working phase to be able to control during the gradual emptying and during use. At least one stringer is also provided and positioned within the storage space to reduce the high compressive loading via the stringer's tensile load capacity. The at least one stringer is attached to two opposing walls and can be subjected to tensile loads. These opposing walls are, for example, the top wall and the bottom wall. It could also be the front wall and the back wall. It would also be conceivable that it is the left wall and the right wall. Through The use of such a stringer ensures the stability of the flat, high-pressure hydrogen tank even at high internal pressure.

In a preferred embodiment of the present invention, the average distance between the top and bottom walls is less than 60%, 50%, 40%, 30% or less than 20% of the average distance between the left wall and the right wall or less than 60%, 50%, 40%, 30% or less than 20% of the mean distance between the front wall and the back wall. As a result, a flat tank differs significantly from a round tank.

In a preferred embodiment of the present invention, a cross section of the flat high-pressure hydrogen tank from the left wall to the right wall has a shape other than a round shape and a substantially round shape. This cross-section penetrates both the left and the right wall and the upper and the lower wall. Additionally or alternatively, a cross section through the flat hydrogen high-pressure tank from the front wall to the rear wall has a shape that deviates from a round shape or a substantially round shape. This cross section passes through both the front wall and the rear wall and the upper and lower wall. The shape is preferably a rectangular shape, and the corners can be rounded. Rather, the extension in two directions is significantly greater (2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times or 15 times) than in another direction such as in particular the construction height. Thus, the extension from the front wall to the rear wall (first direction) and from the left wall to the right wall (second direction) can each be greater than the extension from the top wall to the bottom wall. This results in a flat design and the flat high-pressure hydrogen tank can be carried in the underbody of a means of transport, for example. In this case, the hydrogen flat high-pressure tank can have a very high filling volume because, as a flat tank, it can fill the available installation space in the best possible way.

In a preferred embodiment of the invention, the at least one stringer is attached to the upper and lower walls, in particular glued to these walls. Autoclave hot-melt bonding (80° C. to 180° C.), with or without a blind rivet, can preferably be used here.

In a further preferred embodiment of the invention, more than 4, 5, 6, 8, 10, 12, 14, 16, 20 or more than 25 stringers are provided. At least some of the stringers are transverse stringers and run parallel to one another. This significantly increases the stability of the flat, high-pressure hydrogen tank. At least some of the stringers are also preferred; longitudinal stringers run parallel to one another and perpendicular to the transverse stringers. This again significantly increases the stability of the flat, high-pressure hydrogen tank. Although every stringer also costs installation space and thus filling volume, the advantages clearly outweigh the disadvantages.

The stringers, preferably made of a fiber composite, are pre-assembled as assembly group I together with a thermoplastic diffusion box using a cold adhesive connection. As a result, the assembly of the flat, high-pressure hydrogen tank can be carried out more easily, because the quality of already pre-assembled assemblies can be checked separately for each assembly.

In a further preferred embodiment of the invention, the at least one stringer comprises a multiplicity of prepregs (thin pre-impregnated fiber layer-resin composite layers), which extend from one wall, in particular the upper wall, to the opposite wall, in particular the lower wall, and mainly on become resilient.

In a further preferred embodiment of the invention, the alignment of the fibers of a prepreg layer is rotated in different angular directions relative to the 0° angular direction, preferably rotated by 15°, to align the fibers in the adjacent prepreg layer, so that a multidirectional composite is formed. For example, if eight layers are used, each additional prepreg layer has an angle change of 15° compared to the previous layer, for example (0°, 15°, 30°, 45°, 60°, 75°, 90°). The prepreg layer angles are defined with plus(+) minus(-) signs, starting from 0° to 90° (without + sign) and going beyond the 90° layer up to 180° (- sign), so that layer angles with for example -15°, - 30° etc. until 180° is reached. For example, each layer of prepreg may be 0.125 mm thick. This means that with eight layers you can achieve a component wall thickness of 1 mm in the autoclave-hardened state, although smaller thickness tolerances are permissible.

In a further preferred embodiment of the invention, the prepreg layers of the at least one stringer in the areas where they are attached to the respective wall diverge in at least two different, predominantly opposite directions and form first and second attachment sections. This increases the stability and the stringer can be attached particularly well and flat to the respective wall.

In a further preferred embodiment of the invention, the at least one stringer includes a recess. This recess extends in the direction of the bottom wall and ends at a distance from the bottom wall, as a result of which a barrier is formed in the region of the bottom wall. In this case, this barrier is preferably fastened to that wall which is arranged closer to the floor in the installation location of the flat, high-pressure hydrogen tank. In addition to increased stability, jerky weight shifts in the hydrogen due to the driving situation are dampened by the fuel surge function integrated in the stringer.

The stringer is preferably only attached to the inside of the respective opposing walls (in particular the upper wall, lower wall) and does not penetrate these walls.

In a further preferred embodiment of the invention, the front wall and/or the rear wall is a dished end at the front. The frontal dished end is defined in particular according to DIN 28011 or ASME F&D for metallic, welded dished ends. For fiber composite dished ends, as they can be used for flat tanks, for which welding is not possible, there are still no definitions and standards. In 4G preferred overlap lengths depending on the laminate thickness are shown and in 4F the preferred overlap angles to laminate thickness are shown. For the metallic basket arch bases, which are described in DIN 28013, there are also no definitions and standards for fiber composites. Compared to semi-circular domes, which are preferably used for round pressure bottles, dished heads have the advantage that the installation space can be reduced or the installation space gained via the dished ends in the larger, cylindrical, round zones or, in the case of flat tanks, in the flat parallel zones, resulting in a larger filling volume . This achieves a very high compressive strength with a maximum filling volume. In addition or as an alternative, the left wall and/or the right wall can also be a lateral dished end.

In a further preferred embodiment of the invention, the end dished end of the front and/or rear wall comprises a fastening section which overlaps at least a part of the upper and lower wall and is/is glued to it. This overlap can be both inside and outside. This means that the fastening section is placed on the inside of the upper or lower wall or on the outside thereof or in an intermediate position. Additionally or alternatively, the lateral dished end of the left and/or right wall comprises a fastening section which overlaps at least a part of the upper and lower wall and is glued to it. Hot bonding preferably comes into consideration for the bonding.

In a further preferred embodiment of the invention, for high pressure loads, the fastening section which overlaps with the upper or lower wall is riveted to it.

In a further preferred embodiment of the invention, a diffusion layer is provided over a so-called diffusion box made of thermoplastic materials, preferably PPS, which forms the innermost layer of the hydrogen flat high-pressure tank in order to reduce or even prevent permeations. This diffusion layer ensures that as little hydrogen as possible diffuses through. The diffusion layer should be the densest layer of all, since gaseous fuels in particular can diffuse through the fiber composite layers under high internal pressure, such as hydrogen. The diffusion rates are particularly high for cast variants made of aluminum or other metallic variants. The diffusion layer is also referred to as a "liner", especially for round fiber composite wound tanks of type II to IV.

In another preferred embodiment of the invention, the top wall comprises a first (multidirectional) laminate layer and an overlying second (multidirectional) laminate layer. The bottom wall comprises a first (multidirectional) laminate layer and an overlying second (multidirectional) laminate layer, which represent assembly III of the flat high-pressure hydrogen tank.

In a further preferred embodiment of the invention, a reinforcement winding structure end layer is provided with a certain thickness. This armor arrangement comprises or consists of several carbon fiber strips, the walls being wrapped by the carbon fiber strips. The carbon fiber ribbons are arranged at certain preferred angles other than 0° and 90°, respectively, with respect to the longitudinal axis through the flat, high-pressure hydrogen tank. The angles are preferably greater than 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75° or greater than 80° but preferably less than 85°, 80°, 75°, 70°, 65°, 60°, 55°, 50°, 45°, 40°, 35°, 30°, 25°, 20° , 15° or less than 10°. 0° or 90° angles, which can lead to premature fiber composite failure and thus pressure tank failure, must not be used, since the elongation at break of the carbon fibers with a high required modulus of elasticity is low. In 7 Preferred angles are shown. Ideal angles are between 25° and 45° or in Transverse direction of the hydrogen flat high-pressure tank, i.e. the width, at -75° to -45° in order to be able to use the scissor opening effect at high loads.

In a further preferred embodiment of the invention, a carbon fiber strip forms an angle different from 0° or 90° with another carbon fiber strip. The angle is preferably greater than 25°, 30°, 35°, 40°, 45°.

In another preferred embodiment of the invention, the (flat tank outer layer thickness) armor arrangement is thicker than 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 10mm, 15mm, 20mm, 25mm, 30mm, 40mm, 50mm, but preferably thinner than 60mm, 55mm, 45mm , 35mm 25mm, 20mm, 16mm, 12mm, 9mm, 6mm or thinner than 5mm.

In a further preferred embodiment of the invention, the (valve) fitting arrangement comprises one or more valves and preferably sensors and actuators, via which the hydrogen is filled into the storage space and also removed. Preferably, there is one valve each on the fuel inlet side and the outlet side, ie at least two valve systems, it also being possible for sensors and actuators to be contained in the (valve) fitting arrangement. The hydrogen is filled into the storage space via a first valve and the hydrogen is removed from the storage space via the second valve, in particular at the other end of the pressure tank.

The means of transport according to the invention is a car, bus, truck, tractor or train and comprises at least one flat, high-pressure hydrogen tank and at least one fuel cell, the at least one flat, high-pressure hydrogen tank being constructed in accordance with the previous statements. The means of transport preferably comprises exactly one flat, high-pressure hydrogen tank. This then ensures that energy losses that arise through the use of a large number of valves and distribution systems are avoided. In terms of its shape, the flat high-pressure hydrogen tank according to the invention can be adapted as desired to the available installation space, also as a saddle tank or integral tank, so that the maximum possible amount of hydrogen can be carried along.

The means of transport according to the invention can also be an aircraft, which includes at least one flat, high-pressure hydrogen tank that is constructed in accordance with the previous statements. This aircraft preferably includes a direct hydrogen-capable engine and is therefore not powered electrically by fuel cells or hybrid systems, because fuel cells would be much too heavy for such power ranges and only short and medium-haul flights would be possible without new wing and fuselage concept changes. Preferably, the flat, high-pressure hydrogen tank is additionally held in position by a plurality of spars, stringers and ribs in the wing. The individual hydrogen flat high-pressure tanks (also hydrogen tank boxes) are installed between the wing or fuselage support structures to match the individual construction segments. Hydrogen flat high-pressure tanks are preferably connected to one another, but are controlled separately via valves. The aircraft preferably comprises a large number of flat, high-pressure hydrogen tanks in the form of individual fiber composite boxes, the shape of which is adapted to the installation situation (e.g. in the wings or in the fuselage).

One or more flat, high-pressure hydrogen tanks can also be used on a foundation, for example in a building, outside (for safety reasons) but also inside if this is permissible. One or more flat, high-pressure hydrogen tanks can replace the storage volume of round tank bundles, which consist of up to 12 or more round tanks. This reduces refueling times and saves on logistics and transport costs. Up to two refueling processes per year can currently be required in buildings. With the more advantageous hydrogen flat high-pressure tanks, the refueling time intervals are reduced by a factor of at least 2.5 to 4, depending on the means of transport (car, SUV, bus or commercial vehicle). Using a full 12 fittings with a 12-cylinder bundle with one valve per round tank is a good idea Hydrogen flat high-pressure tanks only require one inlet and one outlet valve or a corresponding fittings system with valves, sensors and actuators. In 13C such a round tank bundle from the prior art is shown. It is immediately apparent that a large number of valves (fittings) and pipe connection lines are required. Pipe connection lines between the individual round tanks are also omitted in the case of the hydrogen flat high-pressure tank, which saves assembly, production, maintenance, safety and inspection costs, as well as weight.

The method according to the invention for producing the hydrogen tank with a large number of stringers comprises, in a first method step, the creation of an assembly with the large number of stringers and a diffusion layer and a first and second laminate layer as the upper and lower wall. In a second method step, the front wall, the rear wall, the left wall and the right wall are added and glued to the assembly. In a third method step, the walls are wrapped with a reinforcement arrangement.

• 1A bis 1C: zeigen verschiedene Ausführungsbeispiele für ein Verkehrsmittel;
• 2A, 2B: zeigen ein Ausführungsbeispiel des erfindungsgemäßen Wasserstoffflachhochdrucktanks zusammen mit mehreren Stringern;
• 3A: zeigt einen Querschnitt durch den erfindungsgemäßen Wasserstoffflachhochdrucktank;
• 3B: zeigt die Befestigung des Stringers;
• 4A, 4B, 4C, 4D, 4E: zeigen den Einsatz eines Klöpperbodens und dessen Befestigung an der oberen und unteren Wand;
• 4F, 4G: erläutern wie der Übergang zwischen dem Klöpperboden und der oberen bzw. unteren Wand zu dimensionieren ist;
• 5: zeigt verschiedene Elemente des Wasserstoffflachhochdrucktanks;
• 6A, 6B: Zeigen verschiedene Ansichten eines teilweise zusammengesetzten Wasserstoffflachhochdrucktanks mit einigen der Elemente aus 5;
• 7: zeigt das Anbringen der Armierungsanordnung in einem Wickelprozess;
• 8: zeigt den Einsatz weiterer Klöpperböden;
• 9: zeigt den Einsatz des Wasserstoffflachhochdrucktanks in einer Tragfläche eines Flugzeugs;
• 10A, 10B: stationäre Anwendungen des Wasserstoffflachhochdrucktanks;
• 11: ein Ablaufdiagramm zur Herstellung des erfindungsgemäßen Wasserstoffflachhochdrucktanks;
• 12A, 12B: verschiedene Baugruppen, um den Wasserstoffflachhochdrucktank zu fertigen; und
• 13A, 13B, 13C: Rundtanks aus dem Stand der Technik.

Various exemplary embodiments of the invention are described below by way of example with reference to the drawings. Identical items have the same reference numbers. The corresponding figures of the drawings show in detail:

• 1A until 1C : show various exemplary embodiments of a means of transport;
• 2A , 2 B 12: show an exemplary embodiment of the flat, high-pressure hydrogen tank according to the invention together with a plurality of stringers;
• 3A : shows a cross section through the flat high-pressure hydrogen tank according to the invention;
• 3B : shows the attachment of the stringer;
• 4A , 4B , 4C , 4D , 4E : show the use of a dished head and its attachment to the upper and lower wall;
• 4F , 4G : explain how the transition between the dished end and the upper or lower wall is to be dimensioned;
• 5 : shows various elements of the flat high-pressure hydrogen tank;
• 6A , 6B : Showing various views of a partially assembled flat-plate high-pressure hydrogen tank with some of the elements shown 5 ;
• 7 : shows the attachment of the reinforcement arrangement in a winding process;
• 8th : shows the use of other dished ends;
• 9 : shows the use of the flat, high-pressure hydrogen tank in a wing of an aircraft;
• 10A , 10B : stationary applications of the hydrogen flat high-pressure tank;
• 11 : a flow chart for the production of the hydrogen flat high-pressure tank according to the invention;
• 12A , 12B : various assemblies to manufacture the flat high-pressure hydrogen tank; and
• 13A , 13B , 13C : Round tanks from the state of the art.

The hydrogen flat high-pressure tank 1 according to the invention is described in the following drawing figures. The hydrogen flat high-pressure tank 1 can be used in a means of transport 100 . 1A shows a means of transport 100 in the form of a car. The hydrogen flat high-pressure tank 1 is preferably arranged in the floor area. The flat, high-pressure hydrogen tank 1 preferably has a cross-sectional shape that deviates from a round cross-sectional shape and, in particular, is rectangular in plan view or approximates to such a shape. In this exemplary embodiment, the hydrogen flat high-pressure tank 1 comprises a corresponding recess into which a fuel cell 101 is inserted.

Air is supplied to the fuel cell 101 via a line system 102 in order to start the corresponding chemical reaction for generating energy. The means of transport 100, in the form of a car, preferably also includes an electrical energy store, in particular in the form of a vehicle battery.

The flat, high-pressure hydrogen tank 1 can be prefabricated as a module, with the fuel cell 101 being pushed into the corresponding installation space in the means of transport 100 . In this case, the connections from the hydrogen flat high-pressure tank 1 to the fuel cell 101 are (automatically) connected to each other.

1B describes the use of a means of transport 100 in the form of a bus. The flat high-pressure hydrogen tank 1 is preferably located above the passengers on the roof. As will be explained later, the flat, high-pressure hydrogen tank 1 can have any shape and can therefore be integrated particularly easily into existing vehicle systems.

1C describes a means of transport 100 in the form of a truck. The flat, high-pressure hydrogen tank 1 is preferably arranged in the area of the trailer and extends parallel to the roadway. In this case, the flat, high-pressure hydrogen tank 1 could have corresponding recesses that rest on the frame of the truck (traction vehicle).

The means of transport 100 preferably comprise exactly one flat, high-pressure hydrogen tank 1.

2A shows an embodiment of the hydrogen flat high-pressure tank 1 according to the invention. The hydrogen flat high-pressure tank 1 comprises an upper wall 2, an opposite lower wall 3, a front wall 4 and an opposite rear wall 5, a left wall 6 and a right wall 7 opposite thereto. The walls 2, 3, 4, 5, 6, 7 delimit a storage space 8. The walls 2, 3, 4, 5, 6, 7 are preferably flat. In particular, for the front wall 4, the rear wall 5, the left Wall 6 and the right wall 7 used dished floors or basket arch floors.

A valve arrangement 10 is provided, which comprises at least one first valve 11 . The valve arrangement 10 is designed to fill hydrogen under pressure into the storage space 8 and remove it from the storage space 8 . In addition to a first valve 11, there is preferably a second valve 12 (see Fig 3A) . The valve assembly 10 can be part of a fitting assembly that also includes sensors and actuators.

At least one stringer 15 is preferably also provided. The stringer 15 is arranged within the storage space 8 . In 2A a plurality of stringers 15 are shown, which are arranged parallel to one another. These stringers 15 extend from the top wall 2 in the direction of the bottom wall 3. They also extend from the region of the front wall 4 in the direction of the rear wall 5. These stringers 15 are referred to as transverse stringers 15a. Also shown are stingers 15 which are offset by approximately 90° to the transverse stringers 15a. These stringers 15 are referred to as longitudinal stringers 15b. In 2 B a single stringer 15 is shown. The at least one stringer 15 is attached to two opposing walls 2, 3 or 4, 5 or 6, 7 and can be subjected to tensile loads. As a result, the stability of the flat, high-pressure hydrogen tank 1 is ensured even at a high internal pressure. In particular, working pressures of 750 bar, filling pressures of 875 bar and a safety factor S of 2.25 and thus 1688 bar can be achieved.

The at least one stringer 15 comprises a multiplicity of prepreg layers which extend from one wall 2 or 4 or 6 to the opposite wall 3 or 5 or 7 and can be subjected to tensile loads in particular. Preferably, these prepreg layers comprise carbon fibers. Furthermore, a multiplicity of prepreg layers are preferably arranged one on top of the other. For example, each prepreg layer can be as thin as 0.125mm. Deviations (+ or -) of less than 100% or less than 50% are conceivable.

The alignment of the fibers of one prepreg layer is twisted to the alignment of the fibers in the adjacent prepreg layer, specifically preferably by approximately 15° in each case, so that a multidirectional bond is present.

The prepreg layers of the at least one stringer 15 diverge in at least or exactly two different, predominantly opposite directions in the areas where they are attached to the respective wall 2, 3 or 4, 5 or 6, 7 form first and second attachment portions 18, 19. In the middle of these attachment portions 18, 19, a channel 16 filled with resin, for example, may be formed.

The at least one stringer 15 comprises at least one recess 17. The at least one recess 17 extends in the direction of the lower wall 3 or in the direction of the second fastening section 19 and ends at a distance from the lower wall 3 or at a distance from the second fastening section 19, whereby a Barrier 24 is formed in the area of the lower wall 3 or in the area of the second fastening section 19 . The stringer 15 preferably comprises a plurality of such recesses 17 which are spaced from one another. As a result, there are connecting webs 27, which are formed from the prepreg layers, which extend from the first fastening section 18 to the second fastening section 19 and connect both fastening sections 18, 19 to one another.

As will be explained later, several stringers 15 can be preassembled with laminate to form an assembly. Such an assembly preferably comprises 2, 3, 4, 5, 6, 8, 10, 12 or more than 16 stringers 15. Such an assembly preferably also includes a thermoplastic diffusion box with a diffusion layer.

In the illustrated embodiment, the at least one stringer 15 is attached to the top wall 2 and to the bottom wall 3 . The attachment preferably takes place by means of an adhesive method, in particular a hot-melt adhesive method. A corresponding form fit is then produced. The extension of the flat high-pressure hydrogen tank 1 from the bottom wall 3 in the direction of the top wall 2 is preferably smaller than the extension from the left wall 6 in the direction of the right wall 7 and/or from the front wall 4 in the direction of the rear wall 5.

The first fastening section 18 preferably runs parallel to the upper wall 2, whereas the second fastening section 19 preferably runs parallel to the lower wall 3. The stringer 15 can be connected, in particular glued, to the upper wall 2 via the first attachment section 18 and to the lower wall 3 via the second attachment section 19 .

3A shows a cross section through an exemplary embodiment of the flat hydrogen high-pressure tank 1 according to the invention. A first valve 11 and a second valve 12 are shown. In addition to the valves 11, 12, the fittings preferably also contain electrically controllable sensors and actuators. The valves 11, 12 are arranged on two opposite walls 6, 7. In in this case the first valve 11 is arranged on the left wall 6 and the second valve 12 on the right wall 7. They could also be arranged on the front wall 4 and the rear wall 5. The valves 11, 12 could also be arranged on the same wall or on immediately adjacent walls. In the valves 11, 12, sensors or actuators can also be integrated.

The top wall 2 comprises a laminate arrangement 20. The same also applies to the bottom wall 3. This can also apply to one or more of the other walls 4,5,6,7. The laminate arrangement 20 preferably comprises a first (multidirectional) laminate layer 21 and a second overlying (multidirectional) laminate layer 2. The laminate arrangement 20 and thus the first and the second laminate layer 21, 22 are preferably planar laminate and more preferably fiber composite parts.

Therefore, the top wall 2 comprises a first (multidirectional) laminate layer 21 and an overlying second (multidirectional) laminate layer 22 or consists of such laminate layers 21, 22. The same applies to the bottom wall 3. This preferably also applies to the front wall 4 and more preferably also for the rear wall 5. The left wall 6 or the right wall 7 can also comprise or consist of a first (multidirectional) laminate layer 21 and an overlying second (multidirectional) laminate layer 22. The first and second laminate layers 21, 22 are preferably of the same thickness. They could also be of different thicknesses.

The first laminate layer 21 is preferably thicker than 2mm, 3mm, 4mm, 5mm, 6mm, 10mm, 15mm, 20mm, 25mm and more preferably thicker than 30mm. However, the first laminate layer 21 is preferably thinner than 40 mm, 35 mm, 30 mm, 25 mm, 20 mm, 15 mm, 13 mm, 10 mm, 8 mm or thinner than 6 mm. The same can also apply to the second laminate layer 22 .

Each of the walls 2, 3, 4, 5, 6, 7 can also comprise further laminate layers.

in the 3A a stringer 15 is also shown. The stringer 15 comprises a multiplicity of prepreg layers which extend from one wall to the opposite wall and are subjected to tensile loads in particular. At the transition to the fastening sections 18, 19 approximately half of the prepreg layers run in one direction and the other half of the prepreg layers run in an opposite other direction.

The prepreg layers of the at least one stringer 15 preferably have a thickness of more than 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 7 mm, 8 mm, 10 mm, 12 mm, 15 mm or more than 20 mm and more preferably less than 30mm, 25mm, 20mm, 15mm, 10mm, 8mm, 6mm or less than 2mm. Preferably, the stringer 15 comprises 2, 3, 4, 5, 6, 7, 8, 10, 15, 20 or more than 15 layers of prepreg.

The prepreg layers preferably comprised carbon fibers. Due to the fact that the prepreg layers diverge at the end (from the middle web), the stringer 15 widens towards its two ends.

The prepreg layers of the at least one stringer 15 are preferably glued to the first laminate layer 21 .

In 3A a diffusion layer 23 is also shown, which preferably forms the innermost layer of the flat, high-pressure hydrogen tank 1 . The diffusion layer 23 can be a thermoplastic part. This diffusion layer 23 is attached to the first laminate layer 21 . In this case, the diffusion layer 23 and the second laminate layer 22 surround the first laminate layer 21. The diffusion layer 23 also extends over the (outer) prepreg layers of the at least one stringer 15, at least over a certain length. The diffusion layer 23 ensures that the hydrogen flat high-pressure tank is as tight as possible and that therefore as little hydrogen as possible escapes unintentionally.

3B shows again the transition or the attachment of the stringer 15 to the top wall 2. It is easy to see that the prepreg layers of the at least one stringer in the area where the stringer 15 is attached to the top wall 2, in at least diverge in two different and predominantly opposite directions. The diffusion layer 23 preferably also extends over at least a certain part of the bent prepreg layers of the stringer 15. In principle, a wedge could be provided which presses the prepreg layers apart.

4A shows a cross section through the flat, high-pressure hydrogen tank 1. The upper wall 2, the lower wall 3, and the left-hand wall 6 and the right-hand wall 7 can be seen. In this case, no stringer 15 is shown. No diffusion layer 23 is shown either. Only the first laminate layer 21 of the laminate arrangement 20 is shown. The left wall 6 and the right wall 7 are in the form of a dished end. In this case it is a lateral dished end. In principle, this could also be the case with the front wall 4 and/or the rear wall 5 . In this case one would speak of a frontal dished end.

The lateral dished bottom of the left and right wall 6, 7 includes a fastening section 25 which preferably runs parallel to the upper and lower wall 2, 3, respectively. The fastening section 25 overlaps at least part of the upper or lower wall 2, 3. The fastening section 25 is glued to the upper or lower wall 2, 3 and preferably also riveted. A corresponding rivet connection 26 is in 4A shown. The riveted joint 26 is preferably used wet. That is, the rivet includes a shroud to prevent the rivet from contacting the carbon fibers that the laminate assembly 20 (first laminate layer 21 and/or second laminate layer 22) preferably comprises. The casing can consist of epoxy resin, for example, or include such.

The fastening section 25 preferably rests on the upper or lower wall 2, 3, respectively. In particular, the fastening portion 25 rests on the first laminate layer 21 which is arranged closer to the storage space 8 . The fastening section 25 is preferably wedge-shaped and rests on a part of the upper or lower wall 2, 3 which is also designed in the shape of a wedge. The first laminate layer 21 is preferably designed in the shape of a wedge at the end on which the fastening section 25 rests. The fastening section 25 is preferably glued to the first and/or second laminate layer 21, 22. Such an adhesive layer 28 is in 6 shown later.

In 4B only an adhesive connection is shown. The second laminate layer 22 is not shown. After the fastening section 25, which preferably runs in the shape of a wedge, is pushed onto the preferably also wedge-shaped part of the first laminate layer 21 of the upper and lower wall 2, 3 and glued to it, a reinforcement arrangement 30 is preferably applied. The reinforcement arrangement 30 preferably comprises carbon strips 31, 32. The reinforcement arrangement 30 is applied by a winding process and preferably surrounds the fastening section 25. As a result, the fastening section 25 is pressed more strongly in the direction of the first laminate layer 21, whereby the stability of the flat hydrogen high-pressure tank 1 is further increased. The fastening section 25 can comprise a receiving trough, so that the reinforcement arrangement 30 comes to rest in this receiving trough.

In 4C the introduction of the rivet connection 26 is also shown. The first laminate layer 21 is connected to the fastening section 25 via the rivet connection 26 . Furthermore, the reinforcement arrangement 30 is preferably applied via the fastening section 25 . The fastening section 25 is therefore located in the middle between the first laminate layer 21 and the reinforcement arrangement 30 and is additionally penetrated by the rivet connection 26 . Preferably, a plurality of riveted joints 26 are used.

4D FIG. 12 further shows the use of the second laminate layer 22. This is preferably not wrapped around the fastening section 25. FIG. The second laminate layer 22 lies on the first laminate layer 21 . The at least one stringer 15 is also shown. In this case, the diffusion layer 23 is not shown. The stringer 15 could be glued to the first or second laminate layer 21, 22. The first attachment portion 18 of the stringer 15 could be bonded to the second laminate layer 22 and the second attachment portion 19 of the stringer 15 could be bonded to the first laminate layer 21 . It could also be the other way around. However, both the first and the second fastening section 18 , 19 of the stringer 15 are preferably glued to the first laminate layer 21 .

4E shows a dished end. The attachment portion 25 is located at the end. Such a dished end allows the flat, high-pressure hydrogen tank 1 to withstand a significantly higher pressure and at the same time ensures that the usable storage space 8 has the maximum volume. The radius r ₁ is selected in a range of preferably 0.8d _a to 1.2d _a and preferably corresponds to approximately 1.0 d _a . The radius r ₂ is chosen in a range of preferably 0.05d _a to 0.15d _a and preferably corresponds to 0.1d _a . The height h is preferably less than 40%, 30%, 25% of d _a . The height h preferably corresponds to 0.1935d _a . The two fastening sections 25 of a dished end are preferably arranged spaced apart from one another by approximately 1.2 to 1.28 d _a . However, this is measured on their outer sides, which are directed away from the storage space 8 .

In 4F shows how large the overlap LÜ is to be dimensioned as a function of the thickness of the first laminate layer 21 . In this case, the overlap LÜ should be selected to be larger, the thicker the first laminate layer 21 is. Various lines for dimensioning are drawn in the diagram. The dotted line represents the minimum overlap LÜ. The solid line shows the maximum overlap LÜ. The optimal length for the overlap LÜ is in between. The dotted and dashed line indicates the optimum here.

In 4G is shown what an angle α between the wedge-shaped fastening section 25 of the dished end and the first laminate layer 21 should be chosen. It can be seen that the thicker the first laminate layer 21 is, the larger the angle α should be selected. Angles of 12° to 18° produce particularly good results.

5 12 shows various elements of the flat, high-pressure hydrogen tank 1. A multiplicity of stringers 15 are shown. These include the first fastening section 18 and the second fastening section 19. The diffusion layer 23 can be inserted between these stringers 15. The diffusion layer 23 is also preferably provided as an assembly and is mounted on appropriate boxes. There is also the laminate arrangement 20 with a first laminate layer 21 and at least one second laminate layer 22. There are also dished ends, which form the left wall 6 and the right wall 7 and the front wall 4 and the rear wall 6. The dished end preferably also comprises the diffusion layer 23, the first laminate layer 21 and the second laminate layer 22. The dished ends, which in this case form the left and right walls 6, 7, also include the valves 11, 12.

6A and 6B show a partial ( 6A) and complete ( 6B) composite hydrogen flat high-pressure tank 1. The diffusion layer 23 is placed between the stringers 15 (e.g. via a thermoplastic diffusion box) and glued to the first laminate layer 21 or the stringers 15 or, more precisely, to the fastening sections 18, 19 of the stringers 15. Furthermore, the adhesive layer 28 is shown, via which the first laminate layer 21 is bonded to the fastening section 25 of the dished end of the front and rear walls 4, 5. The second laminate layer 22 is then applied. This second laminate layer is in 6B shown. In this case, the dished end of the left and right wall 6, 7 with the respective valves 11, 12 is shown. The second laminate layer 22 lies on the first laminate layer 21 . The wrapping of the armor assembly 30 is also shown.

7 1 shows an exemplary embodiment of how the reinforcement arrangement 30, comprising the carbon fiber strips 31, 32, is applied to the walls 2, 3, 4, 5, 6, 7. It can be seen that the carbon fiber strips 30 , 31 are arranged completely or predominantly at an angle which differs from 0° or 90° with respect to the longitudinal axis 29 through the flat high-pressure hydrogen tank 1 . Furthermore, a carbon strip 31 forms an angle with another carbon strip 32 which is different from 0° or 90°. This achieves a particularly high level of stability.

8th shows that in addition to a lateral dished end, which forms the left and right wall 6, 7, there is also an end dished end, which forms the front and rear wall 4, 5. This further increases the stability of the flat, high-pressure hydrogen tank 1 . Overall, the top and bottom walls 2, 3 can be a pultruded casing without the dished heads.

9 shows a means of transport 100 in the form of an airplane. A large number of flat, high-pressure hydrogen tanks (boxes) 1 are integrated in a wing or fuselage structure. Holms 31 of the wing 30 lie in corresponding grooves of the hydrogen flat high-pressure tank 1. These grooves preferably bend the reinforcement arrangement 30 and the laminate arrangement 20, with both arrangements being bent further in the direction of the respective stringer 15. This bend then hits the prepreg layers of the at least one stringer 15 and pushes these fibers or fiber layers apart in different directions. The aircraft has a hydrogen-capable engine and is therefore not powered electrically by fuel cells or hybrid systems, because fuel cells would be far too heavy for such power ranges and only short and medium-haul flights would be possible without new wing and fuselage concept changes. Preferably, the flat, high-pressure hydrogen tank is additionally held in position by a plurality of spars, stringers and ribs in the wing. The individual hydrogen flat high-pressure tanks (also hydrogen tank boxes) are installed between the wing or fuselage support structures to match the individual construction segments. Hydrogen flat high-pressure tanks are preferably connected to one another, but are controlled separately via valves.

10A shows a stationary application in the form of a stationarily arranged flat, high-pressure hydrogen tank 1. In this case, one speaks of a stationary application. This can generally be arranged on a wall such as on a building exterior wall or a building interior wall or in a building basement. The flat high-pressure hydrogen tank 1 can only be mounted on the wall or as in 10 shown still stand on a base plate 40. The stringers 15 are indicated with white lines. Retaining straps 42 are indicated with black lines in order to fasten the flat, high-pressure hydrogen tank 1 to the wall. The first valve 11 is also shown. In addition, a warning lamp 41 with an optional siren is shown, which displays an alarm if the pressure in the hydrogen flat high-pressure tank 1 falls below or exceeds a threshold value and/or hydrogen escapes. The hydrogen flat high-pressure tank 1 can also be arranged outside of a building, for example on a foundation.

10B shows a further stationary application in the form of a stationary arranged flat hydrogen high-pressure tank 1. The hydrogen flat high-pressure tank 1 can be held, for example, in a holding frame 43 and, for example, set up on a foundation (even outdoors). But this is optional. There can be additional sensors 44 or other system and control components 45 . Connection to a higher-level control center is possible, for example to transmit the filling level and the withdrawal quantity or filling quantity per time interval.

11 1 shows a flow chart for a method for producing the flat, high-pressure hydrogen tank 1. A large number of stringers 15 are used here. In a first method step _S1 , an assembly is created. This includes the plurality of stringers 15 and a diffusion layer 23, as well as a laminate arrangement 20 with in particular a first and a second laminate layer 21, 22 as the upper and lower wall 2, 3. The diffusion layer 23 is preferably made of thermoplastic materials via a so-called diffusion box, preferably PPS brought in.

In a further method step S ₂ , the front wall 4, the rear wall 5, the left wall 6 and the right wall 7 are glued to the assembly. It is preferably a dished end.

In a further method step S ₃ , a reinforcement arrangement 30 is wrapped around it, which comprises various carbon strips 31 , 32 . The angular position is preferably chosen as described.

A further sub-process step could also be carried out in the wrapping process step S ₃ . In this sub-process step, the walls 4 , 5 , 6 , 7 that are added could be dished ends that are applied or slid onto the at least one first laminate layer 21 . A further sub-process step could then be carried out, in which the fastening section 25 of the dished end is wrapped with the reinforcement layer 30 .

A further sub-process step could also be carried out, in which the fastening section 25 of the dished end is glued and/or riveted to the at least one first laminate layer 21 .

In principle, it is advantageous if the stringers 15, the assembly with the laminate arrangement 20, the dished heads and the hydrogen flat high-pressure tank 1 are each thermally cured in an autoclave. Thus, the adhesive layer 28 should be cured at over 120°C. The autoclave curing should take place in particular at temperatures between 120°C and 180°C.

In the 12A and 12B various assemblies are described with which the hydrogen flat high-pressure tank 1 according to the invention can be produced.

A first assembly I comprises a multiplicity of stringers 15 and the diffusion layer 23, which was preferably introduced between the stringers 15 with a cold-fixing adhesive. The diffusion layer 23 is preferably provided by a so-called diffusion box made of thermoplastic materials, preferably PPS.

A group II includes the dished end. These either have a valve 11, 12 or not. Sensors or actuators can also be included here.

Assembly III comprises the first and second laminate layers 21, 22 applied to assembly I. Furthermore, an adhesive layer 28 is applied in order to glue the dished end, ie assembly II, to assembly III and connect it thereto.

Assembly IV shows assembly III together with assembly II.

Assembly V shows the finished, flat, high-pressure hydrogen tank 1. In this case, the reinforcement arrangement 30 with the carbon fiber strips 31, 32 is still applied. The carbon fiber tapes 31, 32 are wrapped around the assembly IV. The hydrogen in the hydrogen flat high-pressure tank 1 is gaseous or liquid.

Some features of the flat, high-pressure hydrogen tank 1 are again highlighted separately below.

All stringers 15 are preferably fastened to the same opposite walls 2, 3 or 4, 5 or 6, 7.

Of course, an independent claim could also be directed to the use of a dished end. In this case the stringers 15 would be advantageous developments and could be provided in the dependent claims. It would be sufficient if one wall 2, 3, 4, 5, 6, 7 had the shape of a dished end. However, at least the left and/or the right wall 6, 7 would preferably have such a shape. Additionally or alternatively, this could also be used for the front and/or back lower wall 4, 5 apply. The method claim would then have to be adjusted so that the stringer is only listed in a dependent claim.

Of course, another independent claim could also be directed to the reinforcement arrangement 30 with carbon fiber strips 31, 32. In this case the stringers 15 would be advantageous developments and could be provided in the dependent claims. It could be stated that the carbon fiber strips 30 , 31 are wound independently of one another and are more preferably not arranged congruently one above the other and more preferably are not oriented parallel or perpendicular to the longitudinal axis 29 of the flat high-pressure hydrogen tank 1 .

Of course, another independent claim could also be directed to the flat shape.

The invention is not limited to the exemplary embodiments described. Within the scope of the invention, all features described and/or drawn can be combined with one another as desired.

Claims (22)

Hydrogen flat high-pressure tank (1) for mobile and/or stationary applications, in particular for means of transport (100) such as cars, buses, trucks, tractors, trains, airplanes or ships, and for buildings with the following features: - There are an upper wall (2), a lower wall (3), a front wall (4), a rear wall (5), a left wall (6) and a right wall (7) provided, which has a storage space ( 8) circumscribe; - A valve arrangement (10) with at least one valve (11, 12) is provided and designed to fill hydrogen under pressure into the storage space (8) and to remove it from the storage space (8); - At least one stringer (15) is provided and arranged within the storage space (8); - the at least one stringer (8) is attached to two opposing walls (2, 3 or 4, 5 or 6,7) and can be subjected to tensile loads, which ensures the stability of the flat, high-pressure hydrogen tank (1) even at high internal pressure . Hydrogen flat high-pressure tank (1) after claim 1 , characterized by the following feature: - the average distance between the upper and lower walls (2, 3) is less than 60%, 50%, 40%, 30% or less than 20% of the average distance between the front wall ( 4) and the back wall (5) or less than 60%, 50%, 40%, 30% or less than 20% of the mean distance between the left wall (6) and the right wall (7). Hydrogen flat high-pressure tank (1) after claim 1 or 2 , characterized by the following feature: - the at least one stringer (15) is attached to the top wall (2) and the bottom wall (3). Flat, high-pressure hydrogen tank (1) according to one of the preceding claims, characterized by the following features: - more than 3, 4, 5, 6, 8, 10, 12, 14, 16, 20 or more than 25 stringers (15) are provided; - At least some of the stringers (15) are transverse stringers (15a) and run parallel to one another. Hydrogen flat high-pressure tank (1) after claim 4 , characterized by the following feature: - at least some of the stringers (15) are longitudinal stringers (15b) and run parallel or coaxially to one another and perpendicularly to the transverse stringers (15a). Hydrogen flat high-pressure tank (1) after claim 4 or 5 , characterized by the following feature: - the stringers (15) are assembled together with a thermoplastic diffusion box via a cold glue connection as an assembly. Flat hydrogen high-pressure tank (1) according to one of the preceding claims, characterized by the following feature: - the at least one stringer (15) comprises a multiplicity of prepreg layers which extend from one wall (2 or 4 or 6) to the opposite wall (3 or 5 or 7) and can be subjected to tensile loads. Hydrogen flat high-pressure tank (1) after claim 7 , characterized by the following feature: - the orientation of the fibers of a prepreg layer is rotated to the orientation of the fibers in the adjacent prepreg layer, preferably by about 15°, so that there is a multidirectional bond. Hydrogen flat high-pressure tank (1) after claim 7 or 8th , characterized by the following feature: - the prepreg layers of the at least one stringer (15) run in the areas where they are attached to the respective wall (2, 3 or 4, 5 or 6, 7). at least two different, predominantly opposite, directions apart and form first and second fastening sections (18, 19). Hydrogen flat high-pressure tank (1) after claim 9 characterized by the following features: - the at least one stringer (15) comprises at least one recess (17); - The at least one recess (17) extends in the direction of the lower wall (4) and ends at a distance from the lower wall (4), whereby a barrier (24) is formed in the region of the lower wall (4). Flat hydrogen high-pressure tank (1) according to one of the preceding claims, characterized by the following features: - a cross section through the hydrogen flat high-pressure tank (1) from the left wall (6) to the right wall (7), which also passes through the upper and lower wall (2, 3) runs, has a shape deviating from a round shape or substantially round shape; and/or - a cross-section through the flat high-pressure hydrogen tank (1) from the front wall (4) to the rear wall (5), which also passes through the top and bottom walls (2, 3), has a round shape or substantially round shape deviating shape. Flat, high-pressure hydrogen tank (1) according to one of the preceding claims, characterized by the following feature: - the front wall (4) and/or the rear wall (5) is a dished end at the end; and/or - the left wall (6) and/or the right wall (7) is a lateral dished end. Hydrogen flat high-pressure tank (1) after claim 12 , characterized by the following features: - the end-side dished end of the front and/or rear wall (4, 5) comprises a fastening section (25) which overlaps at least part of the upper and lower wall (2, 3) and is glued to it and /or is riveted; and/or - the lateral dished end of the left and/or right wall (6, 7) comprises a fastening section (25) which overlaps at least part of the upper and lower wall (2, 3) and is glued and/or riveted to it . Flat hydrogen high-pressure tank (1) according to one of the preceding claims, characterized by the following feature: - a diffusion layer (23) is provided, which forms the innermost layer of the flat hydrogen high-pressure tank (1). Flat, high-pressure hydrogen tank (1) according to one of the preceding claims, characterized by the following feature: - the upper wall (2) comprises a first, in particular multidirectional, laminate layer (21) and a second, in particular multidirectional, laminate layer (22) lying thereabove; - the lower wall (3) comprises a first, in particular multidirectional, laminate layer (21) and an overlying second, in particular multidirectional, laminate layer (22). Flat, high-pressure hydrogen tank (1) according to one of the preceding claims, characterized by the following features: - a reinforcement arrangement (30) is provided which comprises or consists of several carbon fiber strips (31, 32), the walls being reinforced by the carbon fiber strips (31, 32 ) are wrapped; - The carbon fiber strips (31, 32) are arranged completely or predominantly at an angle which is different from 0° or 90° in relation to the longitudinal axis (29) through the flat high-pressure hydrogen tank (1). Hydrogen flat high-pressure tank (1) after Claim 16 , characterized by the following feature: - a carbon fiber band (31) forms an angle different from 0° or 90° with another carbon fiber band (32). Hydrogen flat high-pressure tank (1) after Claim 16 or 17 characterized by the following feature: - the armor arrangement (20) is thicker than 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 10mm, 15mm, 20mm, 25mm, 30mm, 40mm, 50mm, but preferably thinner than 60mm, 55mm , 45mm, 35mm 25mm, 20mm, 16mm, 12mm, 9mm, 6mm or thinner than 5mm. Means of transport (100) in the form of a car, bus, truck, tractor, train or ship with at least one flat, high-pressure hydrogen tank (1) and at least one fuel cell (101), the at least one flat, high-pressure hydrogen tank (1) being constructed in accordance with one of the preceding claims. Means of transport (100) in the form of an aircraft with at least one flat hydrogen high-pressure tank (1) and at least one hydrogen turbine, wherein the at least one flat hydrogen high-pressure tank (1) according to one of Claims 1 until 18 is constructed. Stationary application in the form of a stationary arranged flat high-pressure hydrogen tank, in particular for a building, wherein the at least one flat high-pressure hydrogen tank (1) according to one of Claims 1 until 18 is constructed. A method for producing the flat high-pressure hydrogen tank (1) with a plurality of stringers (15) according to one of Claims 1 until 18 is constructed: - Creating (S ₁ ) an assembly with the plurality of stringers (15) and a thermoplastic diffusion box with a diffusion layer (23) and a first and second laminate layer (21, 22) as the upper and lower wall (2, 3) ; - Adding and gluing (S ₂ ) the front wall (4), the rear wall (5), the left wall (6) and the right wall (7) with the assembly; - Wrapping (S ₃ ) of the walls (2, 3, 4, 5, 6, 7) with a reinforcement arrangement (30).

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