Tank for pressurised gas

Abstract

The invention relates to a tank (1) for pressurised gas, in particular hydrogen, comprising a composite structure (2) and a sealing shell (3), wherein the structure (2) comprises at least two rings (4), wherein each ring (4) comprises a continuous fibre reinforcement, wherein the at least two rings (4) are arranged substantially tangential to one another in at least one series extending substantially along a first direction (X), wherein a ring has a height (H), and wherein the number of series (x) substantially determines the height (x*H) of the tank (1), and wherein the number of rings (4) in a series substantially determine the width (W) of the tank (1). The invention also relates to a method for manufacturing a tank for pressurised gas.

Description

[0001] DESCRIPTION

[0002] TITLE: Tank for pressurized gas

[0003] Technical field

[0004] The invention relates to a tank for storing pressurized gas.

[0005] Prior art

[0006] A pressurized gas tank is typically used to transport gas on board a vehicle. The storage pressure of the gas can be high, reaching pressures of around 1000 bars.

[0007] The gas is, for example, hydrogen intended for the propulsion of said vehicle, either by direct combustion in a hydrogen engine, or by production of electricity within a fuel cell.

[0008] Such a tank, while supporting the constraints linked to pressure, must remain lightweight so as not to reduce the vehicle's weight budget. Also, such a tank is, in a known manner, made of composite material. A known embodiment uses a composite structure, comprising fibers embedded in a resin matrix. This structure provides a framework function for the tank, guaranteeing its shape, and guarantees the resistance to mechanical constraints. However, such a material cannot be gas-tight. Also, the structure is lined, over its entire surface, with an envelope or liner made of elastomeric material, ensuring gas-tightness.

[0009] For the purposes of integrating the tank into a vehicle, it is advantageous for the tank to have a flattened shape. A spherical or cylindrical shape is best suited to provide uniform resistance to mechanical stresses caused by pressure. Conversely, a flattened shape results in mechanical stresses that increase the further away from the spherical shape one moves.

[0010] Also, embodiments are sought to obtain a flattened tank.

[0011] The invention proposes to respond to this research by reinforcing the structure through the use of reinforcing rings.

[0012] Summary of the invention

[0013] For this, the subject of the invention is a tank for pressurized gas, in particular hydrogen, comprising a composite structure and a sealing envelope, where the structure comprises at least two rings, each ring comprising a reinforcement of continuous fibers, said at least two rings being arranged substantially tangent, in a series, extending substantially along a first direction, in order to form a flattened tank section, having two substantially planar surfaces, parallel to said first direction, the height of a ring determining the height of the tank and the number of rings in the series determining the width of the tank.

[0014] Particular features or embodiments, usable alone or in combination, are:

[0015] - the tank has a flattened tank section, having two substantially flat surfaces, parallel to the first direction,

[0016] - an extreme ring of a series has a partially circular section and / or an intermediate ring of a series has an oblong or rectangular section with rounded corners,

[0017] - two adjacent rings of a series are assembled together and with at least one, preferably two, shaped inserts to fill the gap between two adjacent rings,

[0018] - the tank comprises at least two series of rings, arranged parallel to each other, in a second direction substantially perpendicular to the first direction, the number of series determining the length of the tank,

[0019] - the envelope comprises hollow pillars passing through, in a third direction substantially perpendicular to the first two directions, shaped to allow the passage of two adjacent rings,

[0020] - the length, in the second direction, of a series is strictly greater than the length of a ring, in the second direction, in order to leave a gap between two pillars, in the second direction,

[0021] - the rings are made of carbon or glass fibers, with long and continuous fibers, embedded in a thermoplastic or thermosetting resin such as an epoxy resin, and preferably an epoxy resin,

[0022] - the envelope is made by overmolding the rings of a series so as to obtain a slice, each slice then being assembled with its neighbor, preferably by welding, even more preferably by hot gas welding or by mirror welding,

[0023] - the tank still includes two half-shells closing the tank at each of the extreme sections.

[0024] According to a second aspect of the invention, a method for producing a tank for pressurized gas, in particular hydrogen, comprising a composite structure and a sealing envelope, comprising the following steps: - producing at least two rings of the structure, - arranging said at least two substantially tangent rings, in a series, extending substantially along a first direction, in a mold, the height of a ring determining the height of the tank and the number of rings in the series determining the width of the tank, - overmolding the rings in the series with a thermoplastic resin of the envelope to form a slice.

[0025] Particular features or embodiments, usable alone or in combination, are:

[0026] - the production of a ring is carried out by spirally winding a fiber, a band or a ribbon around a shape, in order to obtain a reinforcement of continuous fibers,

[0027] - the shape has a partially circular section for an extreme ring of a series and an oblong or rectangular section with rounded corners for an intermediate ring of a series,

[0028] - the method also comprises the following steps: - repetition of the three previous steps to form the desired number of slices, the number of slices determining the length of the tank, - assembly of the slices in a second direction substantially perpendicular to the first direction, preferably by welding, even more preferably by hot gas welding or by mirror welding, - assembly of a half-shell closing the tank at each of the extreme slices,

[0029] - the process also includes the following step: - completion of the structure by an external reinforcement made by filament winding around the assembly formed by the slices and the two half-shells.

[0030] Brief description of the drawings

[0031] The invention will be better understood by reading the following description, given solely by way of example, and with reference to the appended figures in which:

[0032] Figure 1 shows, in perspective view, a slice of the tank,

[0033] Figure 2 shows, in cut perspective view, the slice of Figure 1,

[0034] Figure 3 shows, in perspective view, an assembly of slices,

[0035] Figure 4 shows, in perspective view, an assembly of slices,

[0036] Figure 5 shows a schematic diagram of the construction of the rings,

[0037] Figure 6 shows, in perspective view, a series of rings according to another embodiment,

[0038] Figure 7 shows, in perspective view, a slice according to the embodiment of Figure 6,

[0039] Figure 8 shows, in perspective view, a tank, before rolling up,

[0040] Figures 9 and 10 show in perspective view, a tank in progress and after winding of the external frame.

[0041] Description of the embodiments With reference to Figure 8, the invention relates to a tank 1 for pressurized gas. This gas may in particular be hydrogen under a pressure of up to 1000 bars.

[0042] Such a tank 1 comprises a composite structure 2 and a sealing envelope 3. According to one characteristic, the structure 2 comprises at least two rings 4, in order to provide reinforcement, mainly in a Z direction where the section of the tank 1 is flattened. Each ring 4 comprises a reinforcement of continuous fibers.

[0043] As more particularly illustrated in figures 1, 2, 6, 7, said at least two rings 4 are arranged substantially tangent so as to form a series. It is possible to superimpose more than one series, i.e. x series, along the third direction Z. Said series extends substantially along a first direction X. The dimension along the third direction Z is reduced relative to the other dimensions X, Y, in order to form a flattened tank 1, along the third direction Z. Such a tank 1 has two substantially planar surfaces, parallel to said first direction X and perpendicular to the third direction Z.

[0044] The height H of a ring 4 substantially determines the height H of the tank 1. In the case of a single series, this height is substantially H. If a number x of series is superimposed, the height of the tank 1 is substantially x * H. The number of rings 4 in a series substantially determines the width W of the tank 1.

[0045] A ring is generically designated 4. It distinguishes the intermediate rings 4i, which can be in any number, between 0 and n, from the two extreme rings 4e.

[0046] According to another characteristic, an extreme ring 4e of a series has a partially circular section. In this document, "partially circular" is understood to mean a quarter-circle, semi-circle, or D-shaped section whose ends, adjoining the circular part of the D, are substantially rectilinear. An intermediate ring 4i of a series has an oblong or rectangular section with rounded corners.

[0047] As described above, a slice 9 is obtained by arranging the rings 4 of a series, tangent, along an extension line X, one by one, in a mold, and by overmolding them. The existence of a mold for carrying out the overmolding operation makes it possible not to fix the rings 4 together beforehand, the overmolding then ensuring their assembly.

[0048] According to another characteristic, more particularly illustrated in figures 6 and 7, on the contrary, the rings 4 of a series are assembled together and prior to overmolding. This may concern at least two adjacent rings 4 or all the rings 4 of a series. Optionally, an insert 5, preferably two inserts 5 shaped to fill the gap between two adjacent rings 4, i.e. substantially triangular inserts 5, may be interposed between two adjacent rings 4 thus assembled. An insert 5 makes it possible to provide reinforcement and stiffen the section of a ring 4. The addition of at least one insert 5 also makes it possible to shape a ring 4 into a section shape that is more oblong than rectangular, and thus offer better resistance to pressure.

[0049] Rings 4 are joined tangentially to form a series, extending in the first direction X. The number of rings 4 in a series determines the width W of the tank 1. The rings 4 in a series have substantially the same height H. The intermediate rings 4i are substantially identical to each other and the extreme rings 4e are substantially identical to each other.

[0050] According to another characteristic, it is possible to join several series, comprising the same number of rings 4, by arranging them parallel to each other. This makes it possible to extend the tank 1, in a second direction Y substantially perpendicular to the first direction X. The number of series then determines the length L of the tank 1.

[0051] According to another characteristic, the envelope 3 comprises hollow pillars 6 passing through, in a third direction Z substantially perpendicular to the first two directions X, Y. These hollow pillars 6 are shaped to allow the passage of two adjacent rings 4. A pillar 6 mainly envelops the part where two adjacent rings 4 are tangent and in contact.

[0052] According to another characteristic, the length Is of a series, in the second direction Y, is strictly greater than the length Ia of a ring 4, still in the second direction Y. This characteristic advantageously makes it possible to provide a gap I between two pillars 6, in the second direction Y. This gap I creates a passage allowing gas circulation between the different cells, so as to standardize the gas pressures in a single reservoir volume 1.

[0053] According to another feature, the rings 4 are made of carbon or glass fibers. In order to provide good tensile strength, they are advantageously made of a composite comprising a weft of long, continuous fibers. This weft is embedded in a resin. The resin here is a thermosetting resin, such as an epoxy resin or a thermoplastic resin, with a preference for epoxy resin.

[0054] According to another characteristic, the casing 3 is produced by overmolding the rings 4 of at least one series. The overmolding is preferably carried out one series at a time. The overmolding of a series makes it possible to obtain a slice 9.

[0055] Each slice 9 is then assembled with its neighbor. This assembly is preferably done by welding between the envelope 3 of one series and the envelope 3 of the adjacent series. This welding is preferably carried out by hot gas welding or by mirror welding.

[0056] The assembly of slices 9, as previously described, produces a central section of tank 1. To complete the tank 1, it is appropriate to add to the assembly of slices 9, as illustrated in figures 3, 4, at each open end, a half-shell

[0057] 7, 8 which allows the tank 1 to be closed. This allows the result illustrated in figure to be obtained

[0058] 8. A half-shell 7, 8 is assembled, in a sealed manner, preferably by welding, preferably carried out by hot gas welding or by mirror welding, to each of the extreme edges 9 of the assembly.

[0059] An orifice 13 for filling / drawing water from the tank 1 is advantageously provided in at least one of the half-shells 7, 8.

[0060] According to another characteristic, more particularly illustrated in figures 9 and 10, the tank 1 is further reinforced by completing the structure 2 with at least one external reinforcement 10.

[0061] The structure 2 of the tank 1 according to the invention thus comprises: the rings 4, the possible inserts 5 and at least one external frame 10.

[0062] Such an external armature 10 is advantageously produced by filament winding around the assembly formed by the slices 9 and the two half-shells 7, 8. As illustrated in FIG. 9, a filament winding can be produced according to a first orientation, in an XZ plane. As illustrated in FIG. 10, an alternative or complementary filament winding can be produced according to a second perpendicular orientation, in a YZ plane. It is also possible to produce the winding by continuously varying the winding orientation.

[0063] The invention also relates to a method for producing a tank 1 for pressurized gas, in particular hydrogen, comprising a composite structure 2 and a sealing casing 3. This method comprises the following steps: producing at least two rings 4 of the structure 2, arranging said at least two substantially tangent rings 4, in a series, extending substantially along a first direction X, in a mold, the height H of a ring 4 determining the height H of the tank 1 and the number of rings 4 in the series determining the width W of the tank 1, overmolding the rings 4 in the series with a thermoplastic material of the casing 3 to form a slice 9.

[0064] The thermoplastic material may be polyamide 6, polyamide 66, polyamide 11, polyamide 12, polypropylene, polyethylene, polyethylene terephthalate, or any other thermoplastic resin. According to another characteristic, more particularly illustrated in Figure 5, the production of a ring 4 is carried out by filament winding of a fiber, a strip or a ribbon 12 around a shape 11. A strip is an assembly of several parallel fibers. A ribbon is an assembly of several fibers whose directions are not the same. The fiber, the strip or the ribbon 12 is a wet composite comprising a reinforcement of substantially continuous fibers embedded in a resin matrix. Wet here means that the resin is not yet hardened, in order to allow it to be shaped by winding around the shape 11. The shape 11 is substantially prismatic and its section reproduces the desired section for the ring 4.The filament winding is carried out in a spiral manner in order to be able to wind a fiber, a strip or a ribbon 12 continuously and ultimately obtain a reinforcement of continuous fibers within a ring 4. After filament winding, the wound fiber, strip or ribbon 12 is cut, substantially perpendicular to the axis of the shape 11, into a section, of the desired width for a ring 4. All the rings 4 have substantially the same width.

[0065] According to another feature, the shape 11 has a D-shaped section for a 4th end ring of a series and an oblong or rectangular section with rounded corners for a 4i intermediate ring of a series. Also, two shapes 11 are necessary: ​​one for the 4i intermediate rings and one for the 4th end rings.

[0066] The intermediate rings 4i are symmetrical about the X direction and about the Z direction. The extreme rings 4e are symmetrical about the X direction and symmetrical to each other about the Z direction.

[0067] According to another characteristic, the first three steps: production of rings 4, arrangement of the rings 4 of a series in a mold, and overmolding of the rings 4 of the series to form a slice 9, are repeated so as to obtain as many slices 9 as desired. The number of slices 9 determines the length L of the tank 1. The slices 9 are then assembled along the second direction Y substantially perpendicular to the first direction X. The assembly is preferably carried out by welding, even more preferably by hot gas welding or by mirror welding. The welding is carried out in a sealed manner between the overmolded casing 3 of a slice 9 and the overmolded casing 3 of the adjacent slice 9. A half-shell 7, 8 is then assembled to each of the extreme slices 9, so as to close the tank 1.

[0068] According to another characteristic, the method can advantageously also comprise a step of producing an external reinforcement 10, possibly by filament winding around the assembly formed by the slices 9 and the two half-shells 7, 8. An external reinforcement is necessary. It can be produced by filament winding or by any other method of manufacturing a composite envelope.

[0069] The invention has been illustrated and described in detail in the drawings and the preceding description. The foregoing description should be considered illustrative and given by way of example and not as limiting the invention to this description alone. Numerous alternative embodiments are possible.

[0070] List of reference signs

[0071] 1: tank,

[0072] 2: structure,

[0073] 3: envelope,

[0074] 4: ring,

[0075] 5: insert,

[0076] 6: pillar,

[0077] 7, 8: half-shell,

[0078] 9: slice,

[0079] 10: external frame,

[0080] 11: shape,

[0081] 12: fiber or band or ribbon,

[0082] 13: orifice,

[0083] H: height,

[0084] I: interstice,

[0085] L: length,

[0086] Is: series length, la: ring length,

[0087] W: width,

[0088] X, Y, Z: directions.

Claims

CLAIMS 1. Tank (1) for pressurized gas, in particular hydrogen, comprising a composite structure (2) and a sealing envelope (3), characterized in that the structure (2) comprises at least two rings (4), each ring (4) comprising a reinforcement of continuous fibers, said at least two rings (4) being arranged substantially tangent, in at least one series, extending substantially along a first direction (X), a ring (4) having a height (H), the number of series (x) substantially determining the height (x*H) of the tank (1) and the number of rings (4) of a series substantially determining the width (W) of the tank (1).

2. Tank (1) according to claim 1, having a flattened tank section (1), having two substantially planar surfaces, parallel to the first direction (X).

3. Tank (1) according to any one of claims 1 or 2, wherein an end ring (4e) of a series has a partially circular section and / or an intermediate ring (4i) of a series has an oblong or rectangular section with rounded corners.

4. Tank (1) according to any one of claims 1 to 3, wherein two adjacent rings (4) of a series are assembled together and with at least one, preferably two, inserts (5) shaped to fill the gap between two adjacent rings (4).

5. Tank (1) according to any one of claims 1 to 4, comprising at least two series of rings (4), arranged parallel to each other, in a second direction (Y) substantially perpendicular to the first direction (X), the number of series determining the length (L) of the tank (1).

6. Tank (1) according to any one of claims 1 to 5, where the casing (3) comprises hollow pillars (6) passing through, in a third direction (Z) substantially perpendicular to the first two directions (X, Y), shaped to allow the passage of two adjacent rings (4).

7. Tank (1) according to claim 6, where the length (Is), in the second direction (Y), of a series is strictly greater than the length (la) of a ring (4), in the second direction (Y), in order to provide a gap (I) between two pillars (6), in the second direction (Y).

8. Tank (1) according to any one of claims 1 to 7, where the rings (4) are made of carbon or glass fibers, with long and continuous fibers, embedded in a thermoplastic or thermosetting resin such as an epoxy resin, and preferably an epoxy resin.

9. Tank (1) according to any one of claims 1 to 8, where the casing (3) is produced by overmolding the rings (4) of a series so as to obtain a slice (9), each slice (9) then being assembled with its neighbor, preferably by welding, even more preferably by hot gas welding or by mirror welding.

10. Tank (1) according to any one of claims 1 to 9, further comprising two half-shells (7, 8) closing the tank (1) at each of the end sections (9).

11. Method for producing a tank (1) for pressurized gas, in particular hydrogen, according to any one of claims 1 to 10, characterized in that it comprises the following steps: producing at least two rings (4) of the structure (2), - arrangement of said at least two substantially tangent rings (4), in a series, extending substantially along a first direction (X), in a mold, the height (H) of a ring (4) determining the height (H) of the reservoir (1) and the number of rings (4) in the series determining the width (W) of the reservoir (1), - overmolding of the rings (4) of the series with a thermoplastic resin of the envelope (3) to form a slice (9).

12. Method according to claim 11, wherein the production of a ring (4) is carried out by spirally winding a fiber, a band or a ribbon (12) around a form (11), in order to obtain a reinforcement of continuous fibers.

13. Method according to any one of claims 11 or 12, wherein the shape (11) has a partially circular section for an extreme ring (4e) of a series and an oblong or rectangular section with rounded corners for an intermediate ring (4i) of a series.

14. Method according to any one of claims 11 to 13, further comprising the following steps: - repetition of the three previous steps to form the number of slices (9) desired, the number of slices (9) determining the length (L) of the tank (1), - assembly of the slices (9) in a second direction (Y) substantially perpendicular to the first direction (X), preferably by welding, even more preferably by hot gas welding or by mirror welding, - assembly of a half-shell (7, 8) closing the tank (1) at each of the extreme sections (9).

15. Method according to claim 14, further comprising the following step: - supplementing the structure (2) with an external reinforcement (10) produced by filament winding around the assembly formed by the slices (9) and the two half-shells (7, 8).

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