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, and 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,

[0010] - the structure extends, along the first axis, beyond the ends of said less two cells, by a first high extension and a first low extension enveloping the first collector and by a second high extension and a second low extension enveloping the second collector,

[0011] - a collector comprises at least one recess accommodating a high extension and / or a low extension,

[0012] - a collector further comprises, for each recess, a blocking element entering a recess by blocking a high extension and / or a low extension,

[0013] - a recess is a linear groove and a locking element is a key linear, extending along the second axis,

[0014] - the tank also includes stiffeners connecting the first collector and the second collector, preferably parallel to the first axis, the end of a stiffener being fixed to a collector by blocking, in a linear groove by means of a linear key,

[0015] - the structure is made of composite, and comprises a fabric of woven fibers, non-woven, braided or wound, impregnated in a hardenable resin,

[0016] - 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.

[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, assembling the tubes side by side, threading the fiber fabric of the structure around the tubes, welding two covers, at each end of each tube, positioning the collectors, wrapping the collectors with the extensions, blocking the extensions by force-fitting the linear keys into the linear grooves and 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 and envelope assembly, 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.

[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 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.

[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, the tank 1 also comprises a first collector 11 and a second collector 12.

[0053] 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.

[0054] According to another characteristic, more particularly illustrated in figures 7 and 8, the structure 2 extends, along the first axis X, beyond the ends of said at least two cells 4. Between the two ends, the structure 2 has a ladder-like structure section, enveloping the cells 4. Beyond the ends, only the upper external wall 8 and the lower external wall 8 extend. The upper external wall 8 extends, on the side of the first end, by a first upper extension 13. The lower external wall 8 extends, on the side of the first end, by a first lower extension 14. The upper external wall 8 extends, on the side of the second end, by a second upper extension 15. The lower external wall 8 extends, on the side of the second end, by a second lower extension 16.

[0055] The first upper extension 13 and the first lower extension 14 are able to wind towards each other behind the first collector 11 so as to envelop the first collector 11. The second upper extension 15 and the second lower extension 14 are able to wind towards each other behind the second collector 12 so as to envelop the second collector 12.

[0056] [Fig.7] shows the structure 2, or at least the fiber web of the structure 2, before it is put in place around the cells 4. The extensions are flat, in alignment with the external wall 8 in order to be able to engage the cells 4.

[0057] [Fig.8] shows the structure 2 after its installation around the cells 4. The first, respectively second, upper and lower extensions, are curved, one towards the other so as to envelop and enclose the first collector 11, respectively second collector 12.

[0058] The wrapping of the collectors 11, 12 by the extensions 13-16 contributes to their mutual assembly. However, it is appropriate to complete this assembly by a fixing.

[0059] For this, according to another characteristic, a collector 11, 12 comprises at least one linear groove 17, 18. This linear groove 17, 18 extends along the second axis Y coincident with the main extension axis of the collector 11, 12. This linear groove 17, 18 accommodates a high extension 13, 15 and / or a low extension 14, 16.

[0060] According to another characteristic, a collector 11, 12 also comprises, for each linear groove, a linear key 19, 20 inserted into a linear groove 17, 18, blocking an upper extension 13, 15 and / or a lower extension 14, 16.

[0061] Several configurations are possible and illustrated in figures 1, 2, 12-15. As illustrated in figures 2, 12-15, the same linear groove 17 simultaneously accommodates a high extension 13 and a low extension 14 and locks them by means of a linear key 19.

[0062] Alternatively, as illustrated in [Fig.l], a linear groove accommodates a high extension and blocks it by means of a linear key 19 and another linear groove, advantageously substantially parallel to the first, accommodates a low extension and blocks it by means of another linear key. Such an arrangement can be advantageous in that it frees the middle part of the collector 11, 12 between the two linear grooves.

[0063] It should be noted that the configuration with one or two linear grooves in a collector 11, 12 is independent of the embodiment with one or two layers of cells 4.

[0064] A linear key 19, 20 can lock an extension 13-16 by pressing it against the wall of a linear groove 17, 18, according to different embodiments. According to a first embodiment, more particularly illustrated in [Fig. 12], the linear key 19, 20 is forcibly introduced into a convex linear groove 17, 18 of suitable size. The introduction takes advantage of the deformability of the extension 13-16 to create a return effect which then maintains the linear key 19, 20 in the linear groove 17, 18 while maintaining a compressive force which ensures support on the extension 13-16 and its holding in place.

[0065] According to another embodiment, more particularly illustrated in figures 13-15, the linear key 19, 20 is pressed against the linear groove 17, 18, by interposing at least one extension 13-16, by means of a screw 28. The screw 28 passes through the linear key 19, 20 and is screwed into the collector 11, 12.

[0066] After impregnation with hardenable resin, the curved extensions 13-16 become rigid and hold the collectors 11, 12.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] According to another characteristic, the end of a stiffener 10 is fixed to a collector 11, 12. This fixing is advantageously carried out by blocking, in a linear groove 17, 18 by means of a linear key 19, 20.

[0072] Thus, as illustrated in [Fig. 14], the end of a stiffener 10 can be secured with a collector 11 by introducing its end into a linear groove 17 and pressing it using a linear key 19. The blocking concerns the end of the stiffener 10 and advantageously simultaneously the end of an extension, here the high extension 13.

[0073] 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 make it possible to simplify manufacturing, while remaining substantially rectangular. 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 casing 3. 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].

[0074] 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.

[0075] 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.

[0076] 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 may 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.

[0077] 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.

[0078] 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. However, at least the covers 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.

[0079] The next step is to wind the extensions 13-16 around the collectors 11, 12 so as to envelop them and to lock the extensions 13-16 by forcefully inserting the linear keys 19, 20 into the linear grooves 17, 18 so as to press the extensions 13-16 against the walls of the linear grooves 17, 18.

[0080] The fiber fabric is then impregnated with a curable resin during a sixth step. This impregnation can be carried out by infusion or by RTM or C-RTM injection.

[0081] 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

[0082] 1: reservoir,

[0083] 2: structure,

[0084] 3: casing,

[0085] 4: cell,

[0086] 5: tube,

[0087] 6: first cover,

[0088] 7: second cover,

[0089] 8: external wall,

[0090] 9: internal wall,

[0091] 10: stiffener,

[0092] 11: first collector,

[0093] 12: second collector,

[0094] 13: first upper extension,

[0095] 14: first lower extension,

[0096] 15: second upper extension,

[0097] 16: second lower extension,

[0098] 17: first linear groove,

[0099] 18: second linear groove,

[0100] 19 : first linear key,

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109] 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, and 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).

5. Tank (1) according to any one of claims 1 to 4, where the structure (2) extends, along the first axis (X), beyond the ends of said at least two cells (4), by a first upper extension (13) and a first lower extension (14) enveloping the first collector (11) and by a second upper extension (15) and a second lower extension (16) enveloping the second collector (12).

6. Tank (1) according to any one of claims 1 to 5, wherein a collector (11, 12) comprises at least one recess accommodating a high extension (13, 15) and / or a low extension (14, 16).

7. Tank (1) according to any one of claims 1 to 6, wherein a collector (11, 12) further comprises, for each recess, a blocking element inserted into a recess by blocking therein an upper extension (13, 15) and / or a lower extension (14, 16).

8. A tank (1) according to any one of claims 6 or 7, wherein a recess is a linear groove (17, 18) and wherein a locking element is a linear key (19, 20), extending along the second axis.

9. Tank (1) according to any one of claims 1 to 8, further comprising stiffeners (10) connecting the first collector (11) and the second collector (12), preferably parallel to the first axis (X), the end of a stiffener (10) being fixed to a collector (11, 12) by locking, in a linear groove (17, 18) by means of a linear key (19, 20).

10. Tank (1) according to any one of claims 1 to 9, wherein the structure (2) is made of composite, and comprises a fabric of fibers, woven or non-woven, impregnated in a hardenable resin.

11. Tank (1) according to any one of claims 1 to 10, 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.

12. A method of manufacturing a tank (1) according to any one of claims 10 or 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, assembling 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), wrapping the collectors (11, 12) with the extensions (13-16), locking the extensions (13-16) by force-fitting the locking elements into the recesses (17, 18) and impregnating the fiber fabric with a hardenable resin.

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