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 an internal 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 in that 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] - all the covers at the same end are made of material,

[0010] - said at least two cells are substantially identical and extend side by side parallel coast, on a layer, along a second axis substantially perpendicular to the first axis, so that the reservoir has a substantially flat extension,

[0011] - said at least two cells are substantially identical and extend side by side parallel coast, on two layers, along the second axis,

[0012] - the tank also comprises at least one stiffener arranged between the two layers, 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] - the fiber canvas is made from a single piece,

[0015] - the fiber fabric is woven with an irregular weft and warp distribution, in order to to adapt its strength to the distribution of constraints,

[0016] - the envelope includes surface grooves to facilitate the introduction of the curable resin between the envelope and the fiber fabric.

[0017] 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 lids, at each end of each tube, impregnating the fiber fabric with a hardenable resin. Brief description of the drawings

[0018] 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:

[0019] [Fig-1] shows, in perspective view, a tank according to a first mode of rea lization,

[0020] [Fig.2] shows, in perspective view, a tank according to a second mode of rea lization,

[0021] [Fig.3] shows, in perspective view, a step in the assembly of the tank of [Fig.l],

[0022] [Fig.4] shows, in a view cut perpendicular to the first axis X, the tank of [Fig.l],

[0023] [Fig.5] shows, in perspective view, a step in the assembly of the tank of [Fig.2],

[0024] [Fig.6] shows, in a view cut perpendicular to the first axis X, the tank of [Fig.2],

[0025] [Fig.7] shows, in perspective view, the structure of the tank of [Fig.l], before its assembly,

[0026] [Fig.8] shows, in perspective view, the structure of the tank of [Fig.l], after its assembly,

[0027] [Fig.9] shows, in a view cut perpendicular to the second Y axis, the tank of [Fig.l],

[0028] [Fig. 10] shows, in a view cut perpendicular to the second Y axis, the tank of [Fig.2],

[0029] [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,

[0030] [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,

[0031] [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,

[0032] [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,

[0033] [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,

[0034] [Fig. 16] shows the detail of the connection of a cell to a pipe, according to a first embodiment,

[0035] [Fig. 17] shows the detail of the connection of a cell to a pipe, according to another embodiment,

[0036] [Fig. 18] shows, in partial perspective view, a first collector and envelope assembly, according to a first embodiment,

[0037] [Fig. 19] shows, in partial perspective view, a second collector and casing assembly, according to a first embodiment,

[0038] [Fig.20] shows, in partial perspective view, a first collector and envelope assembly, according to a second embodiment,

[0039] [Fig.21] shows, in partial perspective view, a second collector assembly and envelope, according to a second embodiment. Description of the embodiments

[0040] 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. Here, high pressure is understood to mean a pressure of up to 1000 bars.

[0041] 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.

[0042] 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, per pendicular to the first X axis, a cell section substantially constant along the first X axis.

[0043] 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 the 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In all cases, the structural section substantially reproduces the section of the arrangement of cells 4.

[0048] 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.

[0049] 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 tank 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 2, with a ladder-shaped structural section, allows the cells 4 to be held together and each cell 4 together with the structural box allows high gas pressures to be withstood.

[0050] Such a flat arrangement is particularly advantageous for integrating such a tank 1 into a motor vehicle.

[0051] 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.

[0052] According to another characteristic, all the lids 6, 7 of the same end are made of material. All the lids 6 of the same side are advantageously aligned in the same plane. Also, since all the tubes 5 are adjacent, the lids of two neighboring cells 4 are neighbors. Also, it is advantageous to make all the lids 6, 7 of the same side, corresponding to the same end of the tubes 5, in a single flat piece. The hot air welding process advantageously makes it possible to make the lid / tube assembly from the outside and therefore together for all the tubes 5.

[0053] According to another characteristic, the cells 4 are all substantially identical and extend side by side in parallel.

[0054] According to a first embodiment, illustrated in figures 1, 3, 4, 9, 18 and 19, the cells 4 extend over a layer. This extension is carried out along a second axis Y substantially perpendicular to the first axis X. This makes it possible to give the reservoir 1 a substantially flat extension.

[0055] According to a second embodiment, illustrated in figures 2, 5, 6, 10, 20 and 21, the cells 4 extend side by side in parallel, on two layers. The extension is carried out along the second axis Y. The layers are stacked along a third axis Z perpendicular to the first two axes X, Y.

[0056] More particularly in the context of the second embodiment, 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. A stiffener 10 can typically be made of metallic material or alternatively of 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 length substantially equal to the length of the tank 1, so as to take up the forces, mainly in tension, along the axis of the stiffener 10.

[0057] 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.

[0058] 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].

[0059] 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.

[0060] 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.

[0061] The fibers of the fabric can be glass, carbon, Kevlar or any other material. The fiber fabric can be made by any embodiment. A case can thus be made for each cell. According to another characteristic, the fiber fabric, the frame of the structure 2, is preferably made in a single piece. This can be achieved by weaving, non-weaving, braiding or even winding. This embodiment excludes any sewing or gluing and makes it possible to produce a much more re- assistant.

[0062] According to another characteristic, the fiber fabric, the reinforcement of the structure 2, is woven with an irregular weft and warp distribution. Such a characteristic makes it possible to adapt the strength of the fiber fabric to the potentially irregular distribution of stresses.

[0063] According to another characteristic, the envelope 3, on all or part of its external surface, facing the structure 2, comprises grooves. These grooves form channels. It appears in fact that the space present between structure 2 and envelope 3 is very reduced. Also, when the fiber web is placed around the cells of the envelope, the gap between the two is small. The presence of the grooves makes it possible, by creating channels locally increasing this gap, to facilitate the introduction of the hardenable resin.

[0064] 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. Then, during a fourth 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.

[0065] 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

[0066] 1: reservoir,

[0067] 2: structure,

[0068] 3: envelope,

[0069] 4: alveolus,

[0070] 5: tube,

[0071] 6: first operculum,

[0072] 7: second operculum,

[0073] 8: external wall,

[0074] 9: internal wall,

[0075] 10: stiffener,

[0076] 11: first collector,

[0077] 12: second collector,

[0078] 13: first high extension,

[0079] 14: first low extension,

[0080] 15: second high extension,

[0081] 16: second low extension,

[0082] 17: first linear groove,

[0083] 18: second linear groove,

[0084] 19: first linear key,

[0085] 20: second linear key,

[0086] 21: first conduct,

[0087] 22: second pipe,

[0088] 23: valve,

[0089] 24: first connection,

[0090] 25: second connection,

[0091] 26: insert,

[0092] 27: O-ring,

[0093] 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 (6) 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 claim 3, where all the covers (6, 7) of the same end are made of material.

5. Tank (1) according to any one of claims 1 to 4, wherein said at least two cells (4) are substantially identical and extend side by side parallel, on a layer, along a second axis (Y) substantially perpendicular to the first axis (X), so that the tank (1) has a substantially flat extension.

6. Tank (1) according to any one of claims 1 to 5, wherein said at least two cells (4) are substantially identical and extend side by side in parallel, on two layers, along the second axis (Y).

7. Tank (1) according to claim 6, further comprising at least one stiffener (10) arranged between the two layers, preferably parallel to the first axis (X).

8. A tank (1) according to any one of claims 1 to 7, 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 claim 8, wherein the fiber web is made in one piece.

10. A tank (1) according to any one of claims 8 or 9, wherein the fiber web is woven with an irregular weft and warp distribution, in order to adapt its strength to the stress distribution.

11. A tank (1) according to any one of claims 8 to 10, wherein the casing (3) comprises surface grooves to facilitate the introduction of the curable resin between the casing (3) and the fiber web.

12. Method of manufacturing a tank (1) according to any one of claims 8 to 11, 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), impregnating the fiber fabric with a hardenable resin.

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