High-pressure gas tank

Abstract

High-Pressure Gas Reservoir The invention relates to a reservoir (1) for pressurized gases, such as hydrogen, comprising a structure (2) and a flexible casing, wherein the casing comprises at least two cells, each cell extending along a first axis (X), and in that the structure (2) extends along the first axis (X) and has, perpendicular to the first axis (X), a ladder-like structural section, comprising an outer wall surrounding the outer periphery of said at least two cells and, for each pair of adjacent cells, an inner wall separating the cells of the pair, and being integral, at both ends, with the outer wall. Abbreviated figure: Figure 1

Description

Title of the invention: Tank for high-pressure gas Technical field

[0001] The invention relates to a tank for high-pressure gas, such as hydrogen. High pressure means a pressure of up to 1000 bars. Prior art

[0002] It is known to produce a tank for high-pressure gas with a structure, typically made of composite, ensuring resistance to structural mechanical stresses, lined with a flexible envelope, ensuring sealing, pressed against the structure.

[0003] For certain applications, and in particular for applications on board motor vehicles, a substantially flat and plane tank shape is sought after in order to facilitate integration. Such a shape is delicate in that it causes structural constraints linked to high pressure.

[0004] The present invention presents an ingenious paradigm which advantageously responds to this problem. Summary of the invention

[0005] The invention proposes to provide a tank for pressurized gas, such as hydrogen, comprising a structure and a flexible envelope, where the envelope comprises at least two cells, one cell extending along a first axis and the structure extends along the first axis and has, perpendicular to the first axis, a ladder-like structure section, comprising an external wall surrounding the external periphery of said at least two cells and for each pair of neighboring cells, an internal wall separating the cells of the pair, and being integral, at its two ends, with the external wall.

[0006] Particular characteristics or embodiments, usable alone or in combination, are:

[0007] - a cell has, perpendicular to the first axis, a cell section sen possibly constant along the first axis,

[0008] - each cell comprises a tube along the first axis, preferably made by extrusion, a first cover arranged at a first end of the tube and a second cover arranged at a second end of the tube, substantially flat along a plane perpendicular to the first axis, preferably produced by injection, assembled in a sealed manner at the end, preferably by welding, still preferably by hot air welding or by mirror welding,

[0009] - the tank further comprises a first collector extending mainly along a second axis, substantially perpendicular to the first axis, and arranged in contact with all first ends of said at least two cells and a second collector extending mainly along the second axis and arranged in contact with all second ends of said at least two cells, each cell being fluidically connected to at least one collector,

[0010] - a cover is adhered by overmolding to the adjacent collector,

[0011] - a collector further comprises a pipe extending along the second axis on the entire length of the collector, said pipe being fluidically connected to a tank filling / drawing valve and / or being fluidically connected to at least one cell,

[0012] - the tank also includes stiffeners connecting the first collector and the second collector, preferably parallel to the first axis,

[0013] - the structure is made of composite, and comprises a fabric of woven fibers, non-woven, braided or wound, impregnated in a hardenable resin,

[0014] - a collector is made of metallic material, preferably of light alloy or in composite material with high mechanical resistance, at least on its external surface.

[0015] According to a second aspect of the invention, a method of manufacturing such a tank comprising the following operations: manufacturing, for each of said at least two cells, a tube, preferably by extrusion, arranging the tubes side by side, threading the fiber fabric of the structure around the tubes, welding two covers, at each end of each tube, placing the collectors in place and impregnating the fiber fabric with a hardenable resin. Brief description of the drawings

[0016] The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended figures in which:

[0017] [Fig-1] shows, in perspective view, a tank according to a first mode of rea lization,

[0018] [Fig.2] shows, in perspective view, a tank according to a second mode of rea lization,

[0019] [Fig.3] shows, in perspective view, a step in the assembly of the tank of [Fig.l],

[0020] [Fig.4] shows, in a view cut perpendicular to the first axis X, the tank of [Fig.l],

[0021] [Fig.5] shows, in perspective view, a step in the assembly of the tank of [Fig.2],

[0022] [Fig.6] shows, in a view cut perpendicular to the first axis X, the tank of [Fig.2],

[0023] [Fig.7] shows, in perspective view, the structure of the tank of [Fig.l], before its assembly,

[0024] [Fig-8] shows, in perspective view, the structure of the tank of [Fig.l], after its assembly,

[0025] [Fig.9] shows, in a view cut perpendicular to the second Y axis, the tank of [Fig.l],

[0026] [Fig. 10] shows, in a view cut perpendicular to the second Y axis, the tank of [Fig.2],

[0027] [Fig. 11] shows, in a view cut perpendicular to the first axis X or to the second axis Y, the detail of the assembly of a lid of a cell,

[0028] [Fig. 12] shows, in a view cut perpendicular to the second Y axis, the detail of the fixing of the structure on a collector, according to a first embodiment,

[0029] [Fig. 13] shows, in a view cut perpendicular to the second Y axis, the detail of the fixing of the structure on a collector, according to another embodiment,

[0030] [Fig. 14] shows, in a view cut perpendicular to the second Y axis, the detail of the fixing of the structure on a collector, according to another embodiment,

[0031] [Fig. 15] shows, in a view cut perpendicular to the second Y axis, the detail of the fixing of the structure on a collector, according to another embodiment,

[0032] [Fig. 16] shows the detail of the connection of a cell to a pipe, according to a first embodiment,

[0033] [Fig. 17] shows the detail of the connection of a cell to a pipe, according to another embodiment,

[0034] [Fig. 18] shows, in partial perspective view, a first collector and envelope assembly, according to a first embodiment,

[0035] [Fig. 19] shows, in partial perspective view, a second collector and envelope assembly, according to a first embodiment,

[0036] [Fig.20] shows, in partial perspective view, a first collector and envelope assembly, according to a second embodiment,

[0037] [Fig.21] shows, in partial perspective view, a second collector assembly and envelope, according to a second embodiment. Description of the embodiments

[0038] With reference to Figures 1 or 2, the invention relates to a tank 1 for pressurized gas. This gas may be hydrogen under high pressure. High pressure is understood here to mean a pressure of up to 1000 bars.

[0039] Such a tank 1 comprises a structure 2 and a flexible casing 3. The structure is typically rigid and is designed to withstand mechanical stresses, which may be significant due to high pressures. The casing 3 or liner rests on the structure 2 and is designed to ensure gas tightness.

[0040] According to one characteristic, the envelope 3 comprises at least two cells 4. A cell 4 extends mainly along a first axis X. A cell 4 has, perpendicular to the first axis X, a cell section that is substantially constant along the first axis X.

[0041] The structure 2 extends along the first axis X and has, perpendicular to the first axis X, a ladder-like structure section. Said ladder is complementary to an arrangement of cells 4. The structure 2 comprises an external wall 8 closed on itself and surrounding the external periphery of said at least two assembled cells 4. Thus, the section of the external wall 8 substantially reproduces the periphery of the arrangement of cells 4. The structure 2 also comprises, for each pair of neighboring cells 4, an internal wall 9. This internal wall 9, which forms a rung of the ladder, separates the cells 4 of the pair, and is integral with the external wall 8, at the two ends of the internal wall 9, so as to form a tensioner between the two occurrences of the external wall 8. Thus, the structure section follows the section of said cells 4 by surrounding them from the outside.

[0042] According to another characteristic, a cell 4 has, perpendicular to the first axis X, a cell section which is substantially constant along the first axis X.

[0043] For the embodiment of [Fig. 1], with one layer, the structural section has boxes delimited by two passages of the external wall 8, for the top side and the bottom side of the box and by two adjacent internal walls 9 for the left and right sides of the box. Exceptionally, the most extreme cells 4 are surrounded by boxes also bordered on an external side by the external wall 8.

[0044] For the embodiment of [Fig.2], with two layers, the structural section has two layers of boxes. The structural section also comprises a middle internal wall separating the two layers.

[0045] In all cases, the structural section substantially reproduces the section of the arrangement of cells 4.

[0046] The structure 2 is visible in figures 7 and 8, adapted to the first embodiment of the reservoir of [Fig.l], comprising a single layer of cells 4. The set of cells 4, according to this same first embodiment, is visible in [Fig.3]. [Fig.4] illustrates in sectional view the nested assembly of the cells 4 and the structure 2.

[0047] Such an arrangement with cells 4, arranged side by side in an arrangement, allows, each cell being individually capable of withstanding the pressure due to the fact that the section of a cell 4 is balanced, to nevertheless produce a substantially flat reservoir 1, extending in the two directions X and Y. The cells 4 are placed side by side in parallel. The particular conformation of the structure, with a ladder-shaped structural section, allows the cells 4 to be held together and each cell 4 together with the structural box allows the high pressures of gas.

[0048] Such a flat arrangement is particularly advantageous for integrating such a tank 1 into a motor vehicle.

[0049] According to another characteristic, more particularly illustrated in [Fig.3] or 5, each cell 4 comprises a main extension tube 5 along the first axis X. This tube 5, prismatic in that its section is reproduced along the entire length of the first axis X, is preferably produced by extrusion. This tube 5 provides sealing on four sides. The tube 5 is then closed by means of two covers 6, 7, substantially flat along a plane perpendicular to the first axis X. These covers 6, 7 are preferably produced by injection, each arranged at one end of the tube 5. They are assembled in a sealed manner. The assembly is preferably carried out by welding. The welding can be carried out by any welding method. However, the welding is preferably carried out by hot air welding or by mirror welding.The use of one of these two assembly methods advantageously makes it possible to assemble all the lids 6 of all the adjacent tubes 5 in a single operation. [Fig. 11] shows the sectional detail of the assembly of a tube 5 with a lid 6, to close a cell 4.

[0050] According to another characteristic, the tank 1 also comprises a first collector 11 and a second collector 12.

[0051] The first collector 11 extends mainly along a second axis Y, substantially perpendicular to the first axis X. It is arranged in contact with all the first ends of said at least two cells 4. Similarly, the second collector 12 extends mainly along the second axis Y. It is arranged in contact with all the second ends of said at least two cells 4.

[0052] According to another characteristic, a cover 6, 7 is advantageously adhered to the adjacent collector 11, 12. This advantageously makes it possible to achieve perfect sealing of the assembly. The formation of the pipe 24, 25 which ensures fluid communication between the cell 4 and the collector 11, 12 can be carried out by a gas co-injection process.

[0053] In order to constitute a reservoir, each cell 4 is fluidically connected to at least one collector 11, 12. This is achieved, for example, by means of a pipe 24, 25, piercing at least one cover 6, 7 of the cell 4 and fluidically connected to a collector 11, 12.

[0054] According to another characteristic, a collector 11, 12 also comprises a pipe 21. This pipe 21 is integrated into the collector 11, 12. It extends along the second axis Y over the entire length of the collector 11, 12. This pipe 21 is fluidically connected to a valve 23, usable for filling and / or drawing from the reservoir 1. In addition, alternatively or additionally, this pipe 21 is fluidly connected to at least one cell 4, preferably to all the cells 4. The cells 4 are sealed between them. They also constitute elementary reservoirs. The reservoir 1 is made up of the assembly of these elementary reservoirs. These elementary reservoirs must be connected to each other. This is advantageously achieved by a pipe 21, 22 arranged in one of the two collectors 11, 12.

[0055] According to a first embodiment, the first pipe 21 of a first collector 11 is fluidically connected to a valve 23 and to at least one cell 4, via a first connection 24, connecting the first pipe 21 to the interior of the at least one cell 4 by passing through its adjacent cover 6. This makes it possible to connect the reservoir 1 to the outside. According to this same embodiment, the second pipe 22 of the other collector 12 is fluidically connected to all the cells 4, via a series of second connections 25, one per cell, a second connection 25 connecting the second pipe 22 to the interior of a cell 4 by passing through its adjacent cover 7. This makes it possible to connect all the cells 4 to each other. This is for example illustrated in [Fig.9] or in [Fig. 19].

[0056] Alternatively or additionally, the first pipe 21 can connect several cells 4 via first connections 24 and preferably all of them. This is particularly illustrated in [Fig. 18] for a tank with one layer of cells 4 and in [Fig. 20] for a tank with two layers of cells 4. Similarly, the second pipe 22 can be connected to a filling / drawing valve.

[0057] In the embodiment where one of the pipes 21, 22 ensures both the connection with the outside via a valve 23 and the interconnection of all the cells 4, it is possible not to have a second pipe, in the other collector. This is illustrated in [Fig. 10].

[0058] In the embodiment of [Fig. 2], where the cells are arranged in two superimposed layers, the conduit(s) 21, 22 are advantageously doubled, to arrange a conduit 21 opposite each of the layers. This is more particularly illustrated in Figures 2, 10 and 20.

[0059] [Fig. 16] illustrates a detail of a fluid junction between a pipe 21 arranged in a collector 11 and a cell 4 by means of a connection 24. This is, for example, achieved by means of an insert 26, carrying the connection 24, overmolded in the cover 6. The insert 26 has a shape complementary to a bore made in the collector 11 and in which it engages, so as to open the end of the connection 24 into the interior of the pipe 21. The seal can be improved by means of at least one O-ring 27 arranged between the insert 26 and the bore.

[0060] According to another embodiment, more particularly illustrated in [Fig. 17], the pipe 21 is made of material, typically by overmolding, with the lids 6. Such an embodiment guarantees sealing.

[0061] More particularly in the context of the embodiment of [Fig.2], the presence of two superimposed layers of cells 4 advantageously makes it possible to create a passage, substantially central, in a plane X, Y, between the cells 4. According to another characteristic, this passage is advantageously used to arrange at least one stiffener 10. This stiffener 10 is advantageously arranged between the two layers. A stiffener 10 extends mainly in any direction included in the plane X, Y. A stiffener 10 preferably extends along the first axis X, between the two ends of the tank 1.

[0062] According to another characteristic, the stiffener(s) 10 connect the first collector 11 to the second collector 12, preferably parallel to the first axis X. The stiffeners 10 are advantageously fixed to the collectors 11, 12, for example by locking keys.

[0063] A stiffener 10 may typically be made of a metallic material or alternatively of a high-strength composite material. It is typically in the form of a bar of small section, in order to be easily inserted between the cells 4, of a length substantially equal to the length of the tank 1, so as to absorb the forces, mainly in tension, along the axis of the stiffener 10.

[0064] A stiffener 10 is inserted between the wall of a tube 5 and the structure 2, here an internal wall 9. A series of stiffeners 10 can be inserted, as illustrated in figures 6, 10, 14, 20 or 21, between the upper cell and the structure or between the lower cell and the structure 2. Two series of stiffeners 10 can also be introduced, as illustrated in figures 5 or 15, between the upper cell and the structure and between the lower cell and the structure 2.

[0065] According to another characteristic, the section of a cell 4 or cell section is substantially rectangular or oblong, preferably substantially rectangular with rounded corners. Such a rectangular shape makes it possible to arrange a plurality of cells side by side. The rounded corners also make it possible to better distribute the stresses in the composite of the structure 2 and in the plastic of the envelope 3. The rounded corners make it possible to simplify manufacturing, while remaining substantially rectangular. In order to better withstand the significant stresses linked to pressure, the shape of the end cells can be more rounded towards the outside of the tank 1, as illustrated in Figures 3 and 4. Such a characteristic is not obligatory, as illustrated in [Fig.6].

[0066] The primary function of the casing 3 is to ensure gas tightness. For this purpose, the casing 3 is advantageously made of plastic, such as PA6.

[0067] The primary function of the structure 2 is to ensure the mechanical strength of the tank 1, to maintain the casing 3, and to withstand the consequences of high pressures. All This can be achieved with metallic materials. One objective of the tank 1, when it is intended to be mounted on a vehicle, is to be lightweight. Also, according to another characteristic, the structure 2 is preferably made of composite, which is lighter. The structure 2 comprises a fabric of fibers, woven, non-woven, braided or wound, impregnated in a hardenable resin.

[0068] According to another characteristic, a collector 11, 12 is made of metallic material. Such a material makes it possible to provide resistance to the tank 1. This material is preferably made of light alloy. Alternatively, it can still be made of composite material having high mechanical resistance. A collector 11, 12 advantageously has high mechanical resistance, at least on its external surface, in order to be able to tension and fix the structure 2.

[0069] The invention also relates to a method for manufacturing such a tank 1. This method comprises the following operations. During a first step, for each of the cells 4, a tube 5 is manufactured. Given the prismatic shape and the constant section, this manufacturing is preferably carried out by extrusion. The tubes 5 thus obtained are then arranged side by side, according to the desired final arrangement. During a second step, the fiber web of the structure 2, having a ladder structure section corresponding to the arrangement of the tubes 5, is threaded around the tubes 5, its external wall 8 surrounding the arrangement of the tubes 5 and its internal walls 9 being inserted between the adjacent tubes 5. Then, during a third step, the covers 6, 7 are welded to each end of each tube 5. Alternatively, the covers 6 can be welded on one side before the threading step.But, at least the lids 7 on the second side must be welded after threading. During a fourth step, the collectors 11, 12 are placed at the opposite end of the tank 1. Then, during a fifth step, the fiber fabric is impregnated with a curable resin. This impregnation can be carried out by infusion or by RTM or C-RTM injection.

[0070] The invention has been illustrated and described in detail in the drawings and the preceding description. This should be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Numerous alternative embodiments are possible. List of reference signs

[0071] 1: reservoir,

[0072] 2: structure,

[0073] 3: envelope,

[0074] 4: alveolus,

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[0098] 5: tube, 6: first cap, 7: second cap, 8: external wall, 9: internal wall, 10: stiffener, 11: first collector, 12: second collector, 13: first upper extension, 14: first lower extension, 15: second upper extension, 16: second lower extension, 17: first linear groove, 18 : second linear groove, 19: first linear key, 20: second linear key, 21: first pipe, 22: second pipe, 23: valve, 24: first connection, 25: second connection, 26: insert, 27: O-ring, 28: screw.

Claims

Claims

1. Tank (1) for pressurized gas, such as hydrogen, comprising a structure (2) and a flexible envelope (3), characterized in that the envelope (3) comprises at least two cells (4), one cell (4) extending along a first axis (X) and in that the structure (2) extends along the first axis (X) and has, perpendicular to the first axis (X), a ladder-like structure section, comprising an external wall (8) surrounding the external periphery of said at least two cells (4) and for each pair of neighboring cells (4), an internal wall (9) separating the cells (4) of the pair, and being integral, at its two ends, with the external wall (8).

2. Tank (1) according to claim 1, wherein a cell (4) has, perpendicular to the first axis (X), a cell section substantially constant along the first axis (X)

3. Tank (1) according to any one of claims 1 or 2, where each cell (4) comprises a tube (5) along the first axis (X), preferably produced by extrusion, a first cover (6) arranged at a first end of the tube (5) and a second cover (7) arranged at a second end of the tube (5), substantially flat along a plane perpendicular to the first axis (X), preferably produced by injection, assembled in a sealed manner at the end, preferably by welding, still preferably by hot air welding or by mirror welding.

4. Tank (1) according to any one of claims 1 to 3, further comprising a first collector (11) extending mainly along a second axis (Y), substantially perpendicular to the first axis (X), and arranged in contact with all the first ends of said at least two cells (4) and a second collector (12) extending mainly along the second axis (Y) and arranged in contact with all the second ends of said at least two cells (4), each cell (4) being fluidically connected to at least one collector.

5. Tank (1) according to any one of claims 3 or 4, wherein a cover (6, 7) is adhered by overmolding to the adjacent collector (11, 12).

6. Tank (1) according to any one of claims 4 or 5, wherein a collector (11, 12) further comprises a pipe (21) extending along the second axis (Y) over the entire length of the collector (11, 12), said pipe (21) being fluidically connected to a valve (23) for filling / drawing from the tank (1) and / or being fluidically connected to at least one cell (4).

7. Tank (1) according to any one of claims 4 or 5, further comprising stiffeners (10) connecting the first collector (11) and the second collector (12), preferably parallel to the first axis (X).

8. Tank (1) according to any one of claims 1 to 76, wherein the structure (2) is made of composite, and comprises a fabric of fibers, woven, non-woven, braided or wound, impregnated in a sand-hardened resin.

9. Tank (1) according to any one of claims 1 to 8, wherein a collector (11, 12) is made of metallic material, preferably of light alloy or of composite material having high mechanical resistance, at least on its external surface.

10. Method for manufacturing a tank (1) according to any one of claims 8 to 9, characterized in that it comprises the following operations: manufacturing, for each of said at least two cells (4), a tube (5), preferably by extrusion, arranging the tubes (5) side by side, threading the fiber fabric of the structure (2) around the tubes (5), welding two covers (6, 7), at each end of each tube (5), positioning the collectors (11, 12) and impregnating the fiber fabric with a hardenable resin.

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