Storage tank for high-pressure gas

Abstract

The invention relates to a storage tank (1) for a pressurized gas, such as hydrogen, comprising a structure (2) and a flexible liner, where the liner comprises at least two units, one unit extending along a first axis (X), and where the structure (2) extends along the first axis (X) and has a ladder-shaped cross-section perpendicular to the first axis (X), the ladder-shaped cross-section comprising an outer wall, the outer wall surrounds an outer periphery of the at least two cells, and for each pair of adjacent cells, the ladder-shaped cross-section includes an inner wall that separates the cells in the pair and is integrated with the outer wall at both ends of the inner wall.

Description

Technical Field

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

[0002] High pressure gas storage tanks have been designed with a structure, usually made of composite materials, to withstand structural mechanical stresses, and with a flexible liner pressed against the structure to ensure leak tightness.

[0003] For certain applications and in particular for onboard applications in motor vehicles, a substantially flat and planar tank shape is sought for ease of integration. Such shapes are tricky because of the structural constraints they require in connection with the high pressures.

[0004] The present invention proposes an elegant paradigm that advantageously solves this problem. Summary of the invention

[0005] The present invention proposes to provide a storage tank for pressurized gas such as hydrogen, which includes a structure and a flexible liner, wherein the liner includes at least two units, one unit extends along a first axis, and the structure extends along the first axis and has a trapezoidal cross-section perpendicular to the first axis, the trapezoidal cross-section includes an outer wall, which surrounds the periphery of the at least two units, and for each pair of adjacent units, the trapezoidal cross-section includes an inner wall, which separates the units in the pair and is integrated with the outer wall at both ends of the inner wall.

[0006] Specific features or embodiments that may be used alone or in combination are:

[0007] the cell has a substantially constant cell cross section along the first axis perpendicular to the first axis,

[0008] - each unit comprises: a tube along a 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, the first cover and the second cover being substantially flat along a plane perpendicular to the first axis, preferably made by injection moulding, assembled in a leak-tight manner at the ends, preferably by welding, even more preferably by hot air welding or mirror welding,

[0009] - all covers on the same end are made of the same material,

[0010] - the at least two units are substantially identical and extend side by side in parallel on one level along a second axis substantially perpendicular to the first axis, so that the tank has a substantially flat extension,

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

[0012] - the tank further comprises at least one reinforcement element arranged between the two layers, preferentially parallel to the first axis,

[0013] - the structure is made of composite material and comprises a fabric of woven, non-woven, braided or spiral fibers impregnated with a curable resin,

[0014] - the fabric is made of a single piece,

[0015] - the fabric is woven with irregular weft and warp distribution to adapt its strength to the stress distribution,

[0016] - The liner comprises surface grooves to facilitate the introduction of the curable resin between the liner and the fibre fabric.

[0017] According to a second aspect of the invention, a method for manufacturing such a tank comprises the following operations: for each of the at least two units, a tube is manufactured, preferably by extrusion, the tubes are arranged side by side, a structural fiber fabric is threaded around the tubes, two caps are welded at each end of each tube, and the fiber fabric is impregnated with a curable resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention will be better understood by reading the following description, which is given by way of example only, and by referring to the accompanying drawings, in which:

[0019] [ Figure 1 ] is a perspective view of a storage tank according to a first embodiment,

[0020] [ Figure 2 ] is a perspective view of a storage tank according to a second embodiment,

[0021] [ Figure 3 ] shows [ Figure 1 ] is a perspective view of the assembly steps of the storage tank,

[0022] [ Figure 4 ] shows the perpendicular to [ Figure 1 ] a cross-sectional view of the first axis X of the storage tank,

[0023] [ Figure 5 ] shows [ Figure 2 ] is a perspective view of the assembly steps of the storage tank,

[0024] [ Figure 6 ] shows the perpendicular to [ Figure 2 ] a cross-sectional view of the first X-axis of the storage tank,

[0025] [ Figure 7 ] shows [ Figure 1 ] is a perspective view of the structure of the tank before its assembly.

[0026] [ Figure 8 ] shows [ Figure 1 ] is a perspective view of the structure of the tank after assembly.

[0027] [ Fig. 9 ] shows the perpendicular to [ Figure 1 ] is a cross-sectional view of the second Y axis of the storage tank,

[0028] [ Fig.10 ] shows the perpendicular to [ Figure 2 ] is a cross-sectional view of the second Y axis of the storage tank,

[0029] [ Fig.11 ] shows a cross-sectional view perpendicular to the first X axis or the second Y axis with details of the assembly of the cover for the unit,

[0030] [ Fig.12 ] shows a cross-section perpendicular to the second Y-axis according to a first embodiment with details of how the structure is attached to the manifold,

[0031] [ Fig.13 ] shows a cross-sectional view perpendicular to the second Y-axis according to another embodiment, with details of how the structure is attached to the manifold,

[0032] [ Fig.14 ] shows a cross-sectional view perpendicular to the second axis Y according to another embodiment with details of how the structure is attached to the manifold,

[0033] [ Fig.15 ] shows a cross-sectional view perpendicular to the second Y-axis according to another embodiment, with details of how the structure is attached to the manifold,

[0034] [ Fig.16 ] shows the connection details of the unit and the circuit according to the first embodiment,

[0035] [ Fig.17 ] shows the connection details of the unit and the circuit according to another embodiment,

[0036] [ Fig.18 ] shows a partial perspective view of a first manifold and liner assembly according to a first embodiment,

[0037] [ Fig.19 ] shows a partial perspective view of a second manifold and liner assembly according to a first embodiment,

[0038] [ Fig. 20] shows a partial perspective view of a first manifold and liner assembly according to a second embodiment,

[0039] [ Fig.21 ] shows a partial perspective view of a second manifold and liner assembly according to a second embodiment. DETAILED DESCRIPTION

[0040] refer to Figure 1 or Figure 2 The present invention relates to a storage tank 1 for pressurized gas. The gas may be high pressure hydrogen. High pressure is understood in this context to mean a pressure of up to 1000 bar.

[0041] Such a tank 1 comprises a structure 2 and a flexible liner 3. The structure is generally rigid and is designed to withstand mechanical stresses which may be significant due to the high pressures. The liner 3 rests on the structure 2 and is designed to ensure airtightness.

[0042] According to one feature, the lining 3 comprises at least two cells 4. One cell 4 extends mainly along a first X-axis. Perpendicular to the first X-axis, one cell 4 has a substantially constant cell cross section along the first X-axis.

[0043] The structure 2 extends along a first X axis and has a ladder-like cross section perpendicular to the first X axis. This ladder is complementary to the arrangement of the cells 4. The structure 2 comprises a closed outer wall 8 surrounding the periphery of the at least two assembled cells 4. The cross section of the outer wall 8 thus substantially reproduces the periphery of the arrangement of the cells 4. The structure 2 also comprises an inner wall 9 for each pair of adjacent cells 4. This inner wall 9, which forms a rung of the ladder, separates the paired cells 4 and is integrated with the outer wall 8 at both ends of the inner wall 9, forming a tensioner between two occurrences of the outer wall 8. Thus, the structural section follows the cross section of the cells 4, surrounding them from the outside.

[0044] According to another feature, the cell 4 has, perpendicularly to the first X-axis, a substantially constant cell cross section along the first X-axis.

[0045] for[ Figure 1 ] In the first embodiment with one layer shown in FIG. 1 , the structural segment has a chamber bounded by two channels in the outer wall 8 (for the top and bottom sides of the chamber) and by two adjacent inner walls 9 (for the left and right sides of the chamber). In exceptional cases, the endmost unit 4 is surrounded by a chamber that also borders the outer wall 8 on one side.

[0046] for[ Figure 2 ] In the embodiment with two layers shown in FIG. 1 , the structural section has two layers of chambers. The structural section also includes an intermediate inner wall separating the two layers.

[0047] In each case, the structural section substantially reproduces the cross section of the arrangement of the units 4 .

[0048] Structure 2 can be found in Figure 7 and Figure 8 As seen in [ Figure 1 ] shows a first embodiment of the storage tank, comprising a single-layer unit 4. According to the same first embodiment, in [ Figure 3 ] seen in this group of units 4. [ Figure 4 ] shows a cross-sectional view of the interlocking assembly of unit 4 and structure 2.

[0049] However, such an arrangement of the cells 4 arranged side by side in an array enables the creation of a substantially flat tank 1 extending both in the X-direction and in the Y-direction, since each cell can individually withstand the pressure due to the fact that the cross-section of the cell 4 is balanced. The cells 4 are placed side by side and parallel to each other. The specific construction of the structure 2 with the ladder-like structural sections enables the cells 4 to be held together and each cell 4 to be held together with the structural chamber in order to withstand the high gas pressure.

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

[0051] According to another feature, more specifically, Figure 3 ]or Figure 5 As shown, each unit 4 comprises a main extension tube 5 along a first X-axis. This tube 5 is prismatic, in that its cross section reproduces itself along the first X-axis, the tube being preferably manufactured by extrusion. This tube 5 provides sealing on four sides. The tube 5 is then closed by means of two covers 6, 7, which are substantially flat along a plane perpendicular to the first X-axis. These covers 6, 7 are preferably injection-moulded and are each arranged at one end of the tube 5. They are assembled in a leak-tight manner. Assembly is preferably carried out by welding. Welding can be carried out by any welding method. However, welding is preferably carried out by hot air welding or mirror welding. The use of one of these two assembly methods advantageously allows all covers 6 of all adjacent tubes 5 to be assembled in a single operation. [ Fig.11 ] shows a cross-sectional detail of the assembly of the tube 5 with the cover 6 to close the unit 4.

[0052] According to another feature, all covers 6, 7 on the same end are made of the same material. All covers 6 on the same side are advantageously aligned in the same plane. Moreover, since all tubes 5 are adjacent to each other, the covers of two adjacent units 4 are adjacent to each other. It is also advantageous to manufacture all covers 6, 7 on the same side (corresponding to the same end of the tubes 5) in only a single flat piece. The hot air welding process advantageously allows the covers / tubes to be assembled from the outside and thus used together for all tubes 5.

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

[0054] According to a first embodiment, Figure 1 , Figure 3 , Figure 4 , Fig. 9 , Fig.18 and Fig.19 As shown, the unit 4 extends in one layer. This extension occurs along a second Y axis that is substantially perpendicular to the first X axis. This gives the tank 1 a substantially flat extension.

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

[0056] More specifically, in the second embodiment, the presence of two superimposed layers of cells 4 advantageously allows a substantially central channel to be created between the cells 4 in the X, Y plane. According to another feature, the channel is advantageously used to arrange at least one reinforcement 10. The reinforcement 10 is advantageously arranged between the two layers. The reinforcement 10 extends mainly in any direction within the X, Y plane. The reinforcement 10 preferentially extends between the two ends of the tank 1 along the first X axis. The reinforcement 10 can generally be made of a metallic material, or alternatively made of a high-strength composite material. It generally takes the form of a rod with a small cross section so that it can be easily inserted between the cells 4, and its length is substantially equal to the length of the tank 1, so as to absorb forces along the axis of the reinforcement 10, mainly tensile forces.

[0057] The reinforcement 10 is inserted between the wall of the tube 5 and the structure 2, in this case the inner wall 9. Figure 6 , Fig.10 , Fig.14 , Fig. 20 or Fig.21 As shown, a series of reinforcement members 10 may be inserted between the upper unit and the structure or between the lower unit and the structure 2. Figure 5 or Fig.15 As shown, it is even possible to introduce two series of reinforcements 10 between the upper unit and the structure and between the lower unit and the structure 2 .

[0058] According to another feature, the cross section or cell cross section of the cell 4 is substantially rectangular or oblong, preferably substantially rectangular with rounded corners. Such a rectangular shape allows a plurality of cells to be arranged side by side. The rounded corners also help to better distribute the stresses in the composite material of the structure 2 and in the plastic of the lining 3. The rounded corners simplify the manufacturing while maintaining a substantially rectangular shape. Figure 3 and Figure 4 As shown, in order to better withstand the stresses associated with pressure, the shape of the end unit can be more rounded toward the outside of the tank 1. Figure 6 As shown, such features are not mandatory.

[0059] The main function of the lining 3 is to ensure airtightness. To this end, the lining 3 is advantageously made of plastic (such as PA6).

[0060] The main function of the structure 2 is to ensure the mechanical strength of the tank 1, to keep the liner 3 in place, so as to withstand the consequences of high pressure. All of this can be achieved with metal materials. One purpose of the tank 1 when it is intended to be carried on a vehicle is light weight. According to another feature, the structure 2 is preferably made of a lighter composite material. The structure 2 includes a fabric of woven, non-woven, braided or spiral fibers impregnated with a curable resin.

[0061] The fibers of the fabric can be glass, carbon, Kevlar or any other material. The fabric can be produced by any embodiment. Thus, a case can be produced for each unit. According to another feature, the fabric (reinforcement of the structure 2) is preferably made of a single piece. This can be achieved by weaving, non-woven, braiding or even winding. This design eliminates the need for stitching or gluing, thereby producing a more robust structure 2.

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

[0063] According to another feature, the lining 3 comprises grooves on all or part of its outer surface facing the structure 2. These grooves form channels. The space between the structure 2 and the lining 3 is in fact very small. Moreover, when the fabric is placed around the cells of the lining, the gap between the two is small. The presence of the grooves creates channels that locally increase this gap, thus facilitating the introduction of the curable resin.

[0064] The present invention also relates to a method for manufacturing such a storage tank 1. The method comprises the following operations. In the first step, a tube 5 is manufactured for each unit 4. Considering the prismatic shape and the constant cross section, the manufacture is preferably carried out by extrusion. The resulting tubes 5 are then arranged side by side according to the desired final layout. In the second step, a fiber fabric of a structure 2 with a trapezoidal cross section corresponding to the arrangement of the tubes 5 is threaded around the tubes 5, with its outer wall 8 surrounding the arrangement of the tubes 5 and its inner wall 9 inserted between adjacent tubes 5. In the third step, a cover 6, 7 is welded to each end of each tube 5. Alternatively, the cover 6 can be welded on one side before the threading step. However, at least the cover 7 on the second side must be welded after the threading. In the fourth step, the fiber fabric is then impregnated with a curable resin. The impregnation can be carried out by infusion or by RTM or C-RTM injection.

[0065] The invention has been described and illustrated in detail in the drawings and the foregoing description. This must be considered as illustrative and given by way of example, rather than limiting the invention to this description alone. Many alternative embodiments may be employed.

[0066] Reference numerals list

[0067] 1: Storage tank,

[0068] 2: Structure,

[0069] 3: Lining,

[0070] 4: Unit,

[0071] 5: pipe,

[0072] 6: First cover,

[0073] 7: Second cover,

[0074] 8: Outer wall,

[0075] 9: Inner wall,

[0076] 10: Reinforcement,

[0077] 11: First manifold,

[0078] 12: Second manifold,

[0079] 13: The first high extension part,

[0080] 14: first low extension,

[0081] 15: The second highest extension,

[0082] 16: Second lowest extension,

[0083] 17: First linear groove,

[0084] 18: Second linear groove,

[0085] 19: first linear key,

[0086] 20: Second linear key,

[0087] 21: First line,

[0088] 22: Second line,

[0089] 23: Valve,

[0090] 24: first connection part,

[0091] 25: second connection part,

[0092] 26: Insert,

[0093] 27: O-ring,

[0094] 28: Screws.

Claims

1. A storage tank (1) for a pressurized gas such as hydrogen, comprising a structure (2) and a flexible lining (3), characterized in that The lining (3) comprises at least two units (4), one unit (4) extending along a first axis (X), and is characterized in that the structure (2) extends along the first axis (X) and has a trapezoidal cross-section perpendicular to the first axis (X), the trapezoidal cross-section comprising an outer wall (8) surrounding the periphery of the at least two units (4), and for each pair of adjacent units (4), the trapezoidal cross-section comprises an inner wall (9) separating the units (4) in the pair and being integrated with the outer wall (8) at both ends of the inner wall.

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

3. The storage tank (1) according to any one of claims 1 or 2, wherein each unit (4) comprises: a tube (5) along said first axis (X), said tube being preferably produced by extrusion; A first cover (6) arranged at the first end of the tube (5) and a second cover (6) arranged at the second end of the tube (5), the first cover and the second cover being substantially flat along a plane perpendicular to the first axis (X), are preferably manufactured by injection molding, and are preferably assembled at the ends in a leak-proof manner by welding, even more preferably by hot air welding or mirror welding.

4. Tank (1) according to claim 3, wherein all said covers (6, 7) at one end are made of the same material.

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

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

8. Tank (1) according to any one of claims 1 to 7, wherein the structure (2) is made of composite material and comprises a fabric of woven, non-woven, braided or spiral fibers impregnated with a curable resin.

9. Storage tank (1) according to claim 8, wherein the fiber fabric is made of a single piece.

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

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

12. A method for manufacturing a storage tank (1) according to any one of claims 8 to 11, characterized in that The method comprises the following operations: for each of the at least two units (4), manufacturing 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 caps (6, 7) at each end of each tube (5), impregnating the fiber fabric with a curable resin.

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