Tank for pressurized gas

Abstract

The invention relates to a tank for pressurized gas, such as hydrogen, comprising a hollow structure comprising a cylindrical body along an axis, terminated at each end by a hemi-ellipsoidal cap along the axis, a cap being pierced with an orifice, a sealing jacket (3) able to conform to the internal shape of the structure, a base (4), arranged in the orifice, having a substantially rotationally symmetrical shape about the axis, comprising a first cylindrical portion (41) passing through the orifice and a second discoidal portion (42) arranged inside the structure and in contact with the jacket (3), and also an annular seal (5) arranged at the periphery (43) of the second portion (42).

Description

[0001] TITLE: Tank for pressurized gas

[0002] The invention relates to a reservoir for high-pressure gases, such as hydrogen. The reservoir according to the invention is of the type comprising a hollow structure including a cylindrical body, along an axis A, terminated at each end by a hemi-ellipsoidal cap.

[0003] At least one of the two caps has an opening drilled through it, roughly in its center. A sealing envelope or liner, usually made of polymer, conforms to the internal shape of the structure.

[0004] For each opening, a base, allowing for filling and / or drawing, is positioned within the opening. This base has a shape that is essentially a revolution around axis A. It comprises a first, essentially cylindrical, portion that passes through the opening and a second, essentially discoidal, portion located inside the structure and attached to the casing. A base is typically made of a metal alloy, conventionally by machining.

[0005] It is known to produce the composite structure, with a reinforcement of glass or carbon fibers embedded in a plastic matrix, by filament winding around an assembly comprising the base(s) associated with the sealing casing. Filament winding consists of winding a filament, comprising a fiber reinforcement immersed in the soft-phase plastic material, around a mold form—in this case, the sealing casing and the base(s). After winding, the result is treated so that the plastic material hardens, giving the structure its rigidity and strength.

[0006] Due to the stresses exerted on the base, the periphery of the discoidal section cannot have a very fine profile capable of conforming to the profile of the sealing casing. Consequently, a step appears at the boundary between the periphery of the discoidal section of the base and the sealing casing. This step is detrimental because it potentially catches the filament, which could then slip between the casing and the base, or at least end up in an incorrect position. This negatively alters the otherwise uniform distribution of the filament, potentially causing a crack in the tank structure, which could lead to rupture when the tank is subjected to a pressure increase.

[0007] Therefore, a means of perfecting the interface between the periphery of the discoidal part of the base and the sealing envelope is sought. For this purpose, the invention relates to a reservoir for gas under high pressure, such as hydrogen, comprising a hollow structure including a substantially cylindrical body about an axis, terminated at each end by a substantially hemi-ellipsoidal cap about the axis, at least one of the two caps being pierced, substantially in its center, by an orifice, a sealing envelope adapted to conform to the internal shape of the structure, and for each orifice a base, disposed in the orifice, having a substantially revolution shape about the axis, comprising a first substantially cylindrical part passing through the orifice and a second substantially discoidal part disposed inside the structure and in contact with the envelope, and also an annular seal disposed at the periphery of the second part of the base.

[0008] Specific characteristics or embodiments, usable alone or in combination, are:

[0009] - the joint has a wing-shaped cross-section, comprising a thicker section towards the inside and a thinner section towards the outside,

[0010] - the tapered section is shaped to cover the casing and ensure continuity between the base and the casing,

[0011] - the thick part includes a protuberance extending in a substantially radial and centripetal manner,

[0012] - the protuberance has a roughly circular, roughly trapezoidal, or roughly rectangular cross-section,

[0013] - the protrusion is centered relative to the thick part,

[0014] - the protrusion is eccentric relative to the thick part,

[0015] - the periphery includes a groove with a cross-section complementary to that of the protrusion, in order to be suitable for accommodating the protrusion,

[0016] - the protuberance has a thickness between 0.3 and 1 times the thickness of the wing, and preferably between 0.4 and 0.7 times the thickness of the wing,

[0017] - the protrusion has a length between 0.3 and 2 times its thickness and preferably between 0.9 and 1.7 times its thickness,

[0018] - the ratio between the thickness of the thick part and the thickness of the thinned part is between 5 and 20 and preferably between 6 and 14,

[0019] - the wing length is between 3 and 30 mm and preferably between 9 and 14 mm,

[0020] - the thicker part has an inner diameter slightly smaller than the diameter of the bottom of the throat,

[0021] - The ratio between the internal diameter of the thickened section and the diameter of the throat bottom is between 90 and 100%, preferably between 95 and 98%. According to another aspect, a manufacturing process for such a tank comprises the following steps:

[0022] - fitting a seal to the periphery of a base, preferably by insertion, or even more preferably by clipping,

[0023] - securing the sealing envelope to the base,

[0024] - creation of the structure by filament winding.

[0025] The invention will be better understood upon reading the following description, given solely by way of example, and with reference to the figures in the appendix in which:

[0026] Figure 1 shows, in profile view, a reservoir,

[0027] Figure 2 shows, in perspective view, a base equipped with a seal,

[0028] Figure 3 shows a cross-sectional detail of the entire figure 2.

[0029] Figure 4 shows, in perspective view, a base + seal + casing assembly. Figure 5 shows, in cross-section, a detail of the assembly in Figure 4.

[0030] Figure 6 shows, in cross-section, a joint,

[0031] Figure 7 shows, in profile view, a base,

[0032] Figure 8 shows, in profile view, the detail of a groove.

[0033] Description of the implementation methods

[0034] With reference to Figure 1, the invention relates to a reservoir 1 for gases under high pressure, such as hydrogen. This reservoir 1 comprises a hollow structure 2 including a body 21 substantially cylindrical about an axis A, terminated at each end by a cap 22 substantially hemi-ellipsoidal about the axis A, at least one of the two caps 22 being pierced, substantially in its center, by an orifice 23.

[0035] The tank 1 also includes a sealing casing 3 suitable for conforming to the internal shape of the structure 2.

[0036] The reservoir 1 further includes, for each orifice 23, a base 4. Said base 4 is disposed in an orifice 23. A base 4 has a shape substantially of revolution about the axis A. A base 4 comprises a first part 41 substantially cylindrical, making the passage through the orifice 23, and a second part 42 substantially discoidal, disposed inside the structure 2.

[0037] The second part 42 has an internal face, substantially flat, turned towards the inside of the tank 1 and in contact with the casing 3.

[0038] The second part 42 has an outer face, substantially hemispherical, facing outwards from the reservoir 1, tangent to the structure 2 in its hemispherical cap 22. It follows that the periphery 43 of the second part 42, which has a substantially circular shape, forms a triple contact zone between structure 2, shell 3, and base 4. Due to the stresses experienced by the base 4, the profile of said periphery 43 of the base 4 cannot have the tapered shape that would allow the base 4 to smoothly tangent to the shell 3. A step then appears at the level of this periphery 43.

[0039] This detachment is detrimental, in that, during the manufacture of structure 2 by filament winding, the filament may become caught in said detachment, at the risk of causing a critical weakness of structure 2 and therefore of reservoir 1.

[0040] Also, according to one feature, the reservoir 1 further includes an annular seal 5. This seal 5 is located at the periphery 43 of the second part 42 of the base 4.

[0041] The objective of this joint 5 is to occupy the triple contact area located between the base 4, the envelope 3 and the structure 2.

[0042] According to another feature, the joint 5 has a wing-shaped section, comprising a thick portion 51 towards the inside, i.e. on the side of axis A, and a thin portion 52 towards the outside, i.e. on the side opposite axis A.

[0043] The refined part 52, whose radial section decreases with the radius, in that it gradually becomes tangent to the envelope 3, ensures a smooth interface between the base 4 and the envelope 3. Thus, the refined part 52 is shaped to cover the envelope 3 and ensure continuity between the base 4 and the envelope 3.

[0044] The thick part 51 has a section shaped to interface with the periphery section 43 of the base 4.

[0045] As more particularly illustrated in Figure 6, according to another characteristic, the thick part 51 includes a protrusion 54. This protrusion 54 extends mainly in a substantially radial and centripetal manner, relative to the axis A.

[0046] Although it may have any cross-section, according to another characteristic, protuberance 54 has a cross-section that is substantially circular, substantially trapezoidal, or substantially rectangular.

[0047] According to another characteristic, the protuberance 54 is centered relative to the wing profile and the thick part 51.

[0048] According to another alternative feature, the protuberance 54 is eccentric relative to the wing profile and the thick part 51. This eccentricity can be inwards or outwards.

[0049] In order to accommodate the seal 5, according to another feature, the periphery 43 includes a groove 44. This groove 44 has a cross-section complementary to the cross-section of the protrusion 54. Thus, the periphery 43 is suitable for accommodating the protrusion 54 of the thick part 51. Said protrusion 54 acts as a centering device, helping to position and maintain the seal 5 axially in place in the groove 44.

[0050] In what follows, a thickness is measured axially, parallel to axis A, and a length is measured radially.

[0051] According to another characteristic, the protrusion 54 has a thickness e between 0.3 and 1 times the thickness E of the wing, i.e., the thickness E of the profile of the joint 5 taken axially. This thickness e is preferably between 0.4 and 0.7 times the thickness E of the wing.

[0052] Thus, by way of illustration, according to one embodiment, a protrusion 54 has a thickness e of 2 mm, for a thick part 51 having a thickness E of 3.18 mm, i.e. a ratio of 0.63.

[0053] According to another characteristic, the protrusion 54 has a length I between 0.3 and 2 times the thickness e of the protrusion 54. This length I is preferably between 0.9 and 1.7 times said thickness e.

[0054] Thus, by way of illustration, according to one embodiment, a protrusion 54 has a thickness e of 2 mm, for a length I of 3 mm, i.e. a ratio of 1.5.

[0055] According to another characteristic, the ratio between the thickness of the thick part 51 and the thickness of the thinned part 52 is between 5 and 20 and preferably between 6 and 14.

[0056] This is understood in terms of average or maximum thicknesses. Thus, by way of illustration, according to one embodiment, the joint 5 has an average thickness E of the thick part 51 of 7 mm, for an average thickness of the thin part 52 of 0.5 mm, i.e. a ratio of 14.

[0057] According to another characteristic, the wing length L, i.e. the radial length L of the joint 5 section, is between 3 and 30 mm and preferably between 9 and 14 mm.

[0058] According to another characteristic, the thick part 51 has an inner diameter slightly smaller than the diameter of the bottom of the throat 44.

[0059] The seal 5 is advantageously made of an elastomeric material, such as EPDM. This material advantageously has a hardness of at least 70 Shore A.

[0060] The seal 5 also has the capacity to deform, in whole or in part, preferentially elastically. Therefore, a slightly smaller diameter, by a few percent, allows for a seal 5 that must be temporarily stretched to exceed the largest diameter of the groove 44 and be inserted into the groove. Once in place in the groove, the seal 5 attempts to return to its initial size and shrinks. This ensures that the seal 5 clips into the groove, and even, if necessary, provides sustained clamping of the seal 5 against the bottom of the groove. This clipping, with possible clamping, ensures reinforced retention of the seal 5 in the groove.

[0061] According to another characteristic, the ratio between the inner diameter of the thick part 51 and the diameter of the bottom of the groove 44 is between 90 and 100%. This ratio is preferably between 95 and 98%.

[0062] According to another aspect, a manufacturing process for a reservoir 1, as described above, comprises the following steps. In a first step, a seal 5 is placed on the periphery 43 of a base 4. This placement is preferably achieved by insertion. This placement is also preferably achieved by clipping. In a second step, the sealing sleeve 3 is attached to the base 4. This forms a sleeve + base + seal assembly, which can serve as a mold for the next step. Advantageously, thanks to the seal 5, which ensures a smooth joint between the base 4 and the sleeve 3, the step of the prior art no longer appears between the base 4 and the sleeve 3. In a third step, the structure 2 can be produced by filament winding.

[0063] The invention has been illustrated and described in detail in the drawings and the preceding description. This description is to be considered illustrative and given by way of example, and not as limiting the invention to this single description. Numerous embodiments are possible.

[0064] List of reference signs

[0065] 1: reservoir,

[0066] 2: structure,

[0067] 21: cylindrical body,

[0068] 22: hemi-ellipsoidal cap,

[0069] 23: orifice,

[0070] 3: sealing envelope,

[0071] 4: base,

[0072] 41: first part: cylindrical part,

[0073] 42: second part: discoidal part,

[0074] 43: periphery,

[0075] 44: throat,

[0076] 5: annular joint,

[0077] 51: thick part,

[0078] 52: refined part,

[0079] 54: protuberance,

[0080] A: axis, e: thickness of the protuberance, E: thickness of the wing,

[0081] I: length of the protuberance, L: length of the wing.

Claims

8 DEMANDS 1. A reservoir (1) for gases under high pressure, such as hydrogen, comprising a hollow structure (2) including a body (21) substantially cylindrical about an axis (A), terminated at each end by a cap (22) substantially hemisellipsoidal about the axis (A), at least one of the two caps (22) being pierced, substantially in its center, by an orifice (23), a sealing casing (3) adapted to conform to the internal shape of the structure (2), and for each orifice (23) a base (4), disposed in the orifice (23), having a shape substantially of revolution about the axis (A), comprising a first part (41) substantially cylindrical passing through the orifice (23) and a second part (42) substantially discoidal disposed inside the structure (2) and in contact with the casing (3), characterized in that it further comprises an annular seal (5) disposed at the periphery (43) of the second part (42) of the base (4).

2. Reservoir (1) according to claim 1, wherein the seal (5) has a wing-shaped section, comprising a thick portion (51) towards the inside and a tapered portion (52) towards the outside.

3. Reservoir (1) according to claim 2, wherein the refined part (52) is shaped to cover the casing (3) and ensure continuity between the base (4) and the casing (3).

4. Reservoir (1) according to any one of claims 2 or 3, wherein the thick part (51) comprises a protrusion (54) extending substantially radially and centripetally.

5. Reservoir (1) according to claim 4, wherein the protrusion (54) has a substantially circular, substantially trapezoidal or substantially rectangular cross-section.

6. Reservoir (1) according to any one of claims 4 or 5, wherein the protrusion (54) is centered relative to the thick part (51).

7. Reservoir (1) according to any one of claims 4 or 5, wherein the protrusion (54) is eccentric relative to the thick part (51).

8. Reservoir (1) according to any one of claims 4 to 7, wherein the periphery (43) comprises a groove (44) having a cross-section complementary to the cross-section of the protrusion (54), in order to be able to accommodate the protrusion (54).

9. Tank (1) according to any one of claims 4 to 8, wherein the protrusion (54) has a thickness (e) of between 0.3 and 1 times the thickness (E) of the wing and preferably between 0.4 and 0.7 times the thickness (E) of the wing.

10. Reservoir (1) according to any one of claims 4 to 9, wherein the protrusion (54) has a length (I) between 0.3 and 2 times its thickness (e) and preferably between 0.9 and 1.7 times its thickness (e).

11. Reservoir (1) according to any one of claims 2 to 10, wherein the ratio between the thickness (E) of the thick part (51) and the thickness of the thinned part (52) is between 5 and 20 and preferably between 6 and 14.

12. Tank (1) according to any one of claims 2 to 11, where the length (L) of the wing is between 3 and 30 mm and preferably between 9 and 14 mm.

13. Reservoir (1) according to any one of claims 8 to 12, wherein the thick part (51) has an inner diameter slightly smaller than the diameter of the bottom of the throat (44).

14. Reservoir (1) according to any one of claims 8 to 13, wherein the ratio between the inner diameter of the thick part (51) and the diameter of the bottom of the throat (44) is between 90 and 100%, preferably between 95 and 98%.

15. Method of manufacturing a tank (1) according to any one of the preceding claims, comprising the following steps: - placing a seal (5) on the periphery (43) of a base (4), preferably by insertion, even more preferably by clipping, securing the sealing envelope (3) with the base (4), - making the structure (2) by filament winding.

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