PRESSURIZED GAS TANK

Abstract

PRESSURIZED GAS TANK The present invention relates to a pressurized gas tank (1), such as for hydrogen, comprising a metallic base (3) substantially of revolution about an axis (A) comprising a groove (5) substantially cylindrical in the concave of the axis (A) and a casing (6) comprising a neck (7) substantially cylindrical in the oculus of the axis (A) of a diameter substantially identical to the diameter of the groove (5), where the groove (5) accommodates a plastic ring (8) and where the neck (7) is assembled with the ring (8). Figure for the abstract: Figure 1

Description

Title of the invention: TANK FOR PRESSURE GAS Technical field

[0001] The invention relates to a pressurized gas tank, such as hydrogen. More particularly, the invention aims to protect an embodiment of the sealed interface between the base and the envelope or liner. Prior art

[0002] A pressurized gas tank can be made using a composite material structure (fiber reinforcement embedded in a resin matrix) of typically cylindrical shape in the central part, terminated at its two ends by a hemispherical cap.

[0003] In order to be able to fill the gas tank and then draw the gas, the structure typically comprises a through hole, along an axis, conventionally arranged in the center of a hemispherical cap. In this hole is arranged a base, generally metallic, substantially of revolution around a through bore along said axis, arranged substantially aligned with the hole so as to allow filling and / or drawing.

[0004] The composite material structure is not intrinsically gas-tight. Also, its inner surface is lined with an envelope, conventionally made of elastomeric material, ensuring gas-tightness. The shape of this envelope substantially reproduces the inner shape of the structure.

[0005] The base has a substantially cylindrical groove along said axis. The casing has a neck capable of interfacing with the base, coaxially around the bore. This interface should be gas-tight.

[0006] In order to ensure fixing and gas-tightness at the interface between the casing and the base, several embodiments are known. According to a first embodiment, the neck is introduced into the groove and glued. However, gluing is a complicated process, difficult to control and requiring a very long drying time, which can reach 8 hours per tank. According to another embodiment, an additional part pinches the neck in the groove so as to hold it in the groove, the seal being ensured by the pinching. This approach requires an additional part, and is difficult to implement.

[0007] Also, another approach is sought to achieve a watertight assembly between the neck of the envelope and the base. Summary of the invention

[0008] The invention proposes to proceed in two stages: firstly, a A plastic ring is placed and fixed in the groove, and then the neck of the envelope is assembled with this ring.

[0009] The subject of the invention is a tank for pressurized gas, such as hydrogen, comprising a metal base substantially of revolution around an axis comprising a groove substantially cylindrical in hollow along the axis and an envelope comprising a neck substantially cylindrical in full along the axis, of diameter substantially identical to the diameter of the groove, where the groove accommodates a ring made of plastic material and in that the neck is assembled with the ring.

[0010] Particular characteristics or embodiments, usable alone or in combination, are:

[0011] - the ring is made and placed in the groove by overmolding,

[0012] - the ring is made of polyamide or any other thermoplastic material,

[0013] - the ring occupies the bottom of the groove,

[0014] - the ring protrudes from the groove, preferably onto a flat surface of the base, so as to present an interface surface increased relative to the width of the groove,

[0015] - the groove has a depth to width ratio greater than 1, preferably greater than 3, even more preferably greater than 5,

[0016] - the surface of the groove is prepared for overmolding by depositing a primer by attachment or by overmolding a thin layer of plastic,

[0017] - the surface of the groove is prepared for overmolding by plasma treatment,

[0018] - the neck is assembled with the ring by welding, preferably carried out by in infrared or hot gas, preferably still carried out by rotary friction.

[0019] According to a second aspect of the invention, a method of producing such a reservoir comprising the following steps:

[0020] - production and installation of the ring in the groove of the base by overmolding,

[0021] - assembly of the envelope by welding its neck with the ring. Brief description of the drawings

[0022] 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:

[0023] [Fig.l] shows, in a sectioned axial view, a tank according to a first embodiment,

[0024] [Fig.2] shows, in a sectioned axial view, a tank according to another embodiment. Description of the embodiments

[0025] With reference to [Fig.l], the invention relates to a tank 1 for pressurized gas. The gas may, for example, be hydrogen. The pressure may be raised up to typically 700 bars.

[0026] Such a tank 1 comprises a structure 2. This structure is typically made of a composite material, comprising a fiber reinforcement, typically glass or carbon, embedded in a plastic resin matrix. This structure 2 takes, for example, the form of a cylinder terminated at its two ends by hemispherical caps. The structure 2 is conventionally pierced with an opening, in order to allow filling and / or drawing, advantageously arranged in the center of a hemispherical cap. The tank 1 also comprises a base 3, most often metallic, advantageously made of aluminum, substantially of revolution around an axis A. The base 3 is arranged in said opening. The base 3 is advantageously pierced with a bore 4 of axis A. It comprises a groove 5 substantially in the form of a hollow cylinder, of axis A.The reservoir 1 also comprises an envelope 6, of a shape adapted to follow the internal wall of the structure 2 and comprising a neck 7 substantially in the form of a solid cylinder, of axis A. The neck 7 is placed opposite the groove 5 of the base 3 and has a diameter substantially identical to the diameter of the groove 5 or of the ring 8.

[0027] According to a characteristic of the invention, a ring 8 is arranged in the groove 5. The ring 8 is made of plastic material and is secured to the metal of the base 3.

[0028] The connection between the plastic ring 8 and the metal groove 5 can be achieved by any means. It is thus possible to compress the ring 8 by force in the groove 5. It is also possible, additionally or alternatively, to glue the ring 8 in the groove 5.

[0029] According to another preferred characteristic, the ring 8 is produced and put in place by injection molding in the groove 5, which is also called overmolding. The base 3 is placed in a mold and the plastic of the ring 8 is injected by molding in the groove 5.

[0030] According to another characteristic, the plastic material of the ring 8 is polyamide. Alternatively, this plastic material can still be any thermoplastic material.

[0031] According to another characteristic, more particularly illustrated in [Fig.l], the ring 8 is shaped to occupy the bottom of the groove 5.

[0032] According to another characteristic, more particularly illustrated in [Fig.2], the ring 8 is shaped to occupy the bottom of the groove 5 and also to project beyond the groove 5. Preferably, the ring 8 projects beyond the groove 5, advantageously onto a flat surface of the base 3 bordering the groove 5 and substantially perpendicular to the axis A. According to such an embodiment, the ring 8 has an increased interface surface, much wider than the width of the groove 5. This characteristic advantageously makes it possible to increase the possible interface surface with the neck 7 of the casing 6. This also makes it possible to accommodate dimensional variations of said neck 7. These dimensional variations may, for example, be variations in the thickness of the fabric of the neck 7 or a defect in the circularity of the neck 7 or a defect in the coaxiality of the neck 7 with the axis A.

[0033] In relation to the feature of producing the casing 6 by blow molding, this dimensional accommodation tolerance is advantageous in that this embodiment by blow molding can create this type of dimensional deviations.

[0034] According to another advantageous characteristic, the groove 5 has a depth to width ratio greater than 1, preferably greater than 3, even more preferably greater than 5. This characteristic contributes to improving the fixing of the ring 8 to the groove 5 by adhesion.

[0035] According to another characteristic, the adhesion of the plastic material of the ring 8 to the metal surface of the base 3 is greatly improved by preparing the metal surface of the base 3 prior to overmolding. This preparation can be carried out by depositing a bonding primer.

[0036] According to one characteristic, the bonding primer is a thermosetting or thermoplastic resin.

[0037] Alternatively, the preparation of the metal surface of the base 3 may consist of overmolding a thin layer of plastic. Here, a thin layer is understood to mean a layer with a thickness of less than 1 mm.

[0038] This overmolding can be achieved by a particular plastic in that it has improved adhesion with the metal surface. This plastic can also be the same as that of the ring in order to improve the resistance of the overmolding of the ring 8.

[0039] Alternatively or additionally, this preparation can be carried out by a plasma treatment which produces a superficial modification of the surface condition, promoting the subsequent adhesion of the bonding primer or directly of the overmolded plastic material.

[0040] It is also possible to geometrically modify the surface of the base 3 at the level of the surfaces in contact with the ring 8. This may include machining the surfaces, so as to create a texturing, a relief, such as knurling, scratches and / or micro-grooves. This aims to increase the adhesion of the plastic material of the ring 8.

[0041] According to another characteristic of the invention, the neck 7 of the casing 6 is then assembled with the ring 8 by welding. Said welding is preferably carried out by infrared or by hot gas. This makes it possible to heat one, the other or both parts in order to produce a surface fusion. The two parts are then applied against each other, carrying out the welding.

[0042] Preferably, the ring 8 on the one hand and the neck 7 of the casing 6 are made of the same plastic material to improve the strength and durability of the welding assembly.

[0043] According to a preferred embodiment, this welding is carried out by rotary friction. In this embodiment, one, the other or both parts to be assembled are set in relative motion and applied against each other. No prior heating is necessary. The relative movement creates, during application, friction, creating heating, producing a fusion of the parts at their interface, allowing welding. In the present case, the relative movement is advantageously a rotation around the axis A. Preferably, the base 3 is set in rotation relative to a fixed casing 6. According to another feature, the casing 6 is made by blow molding, prior to welding. This embodiment is advantageous in that it allows for faster and therefore less expensive production. A disadvantage of this embodiment is a greater dimensional dispersion. However, as previously described, this dispersion is easily accommodated by subsequent assembly by welding. This is true in the embodiment of [Fig. 1]. This is even more true in the embodiment of [Fig. 2], where the receiving surface of the ring 8 is increased.

[0044] The invention also relates to a method for producing such a tank 1. This method comprises the following steps. During a first step, the ring 8 is produced and placed in the groove 5, preferably by overmolding. During a subsequent step, the casing 6 is assembled by welding its neck 7 with the ring 8.

[0045] 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

[0046] 1: reservoir,

[0047] 2: structure,

[0048] 3: base,

[0049] 4: bore,

[0050] 5: throat,

[0051] 6: envelope,

[0052] 7: neck,

[0053] 8: ring,

[0054] A: axis.

Claims

Claims

1. Tank (1) for pressurized gas, such as hydrogen, comprising a metal base (3) substantially of revolution around an axis (A) comprising a groove (5) substantially cylindrical in hollow of axis (A) and an envelope (6) comprising a neck (7) substantially cylindrical in full of axis (A) of diameter substantially identical to the diameter of the groove (5), characterized in that the groove (5) accommodates a ring (8) made of plastic material and in that the neck (7) is assembled with the ring (8), and in that the ring (8) occupies the bottom of the groove (5).

2. Tank (1) according to claim 1, where the ring (8) is produced and placed in the groove (5) by overmolding.

3. Tank (1) according to any one of the preceding claims, wherein the ring (8) is made of polyamide or any other thermoplastic material.

4. Tank (1) according to any one of the preceding claims, where the ring (8) projects from the groove (5), preferably onto a flat surface of the base (3), so as to present an interface surface increased relative to the width of the groove (5).

5. Tank (1) according to any one of the preceding claims, where the groove (5) has a depth to width ratio greater than 1, preferably greater than 3, even more preferably greater than 5.

6. Tank (1) according to any one of the preceding claims, wherein the surface of the groove (5) is prepared for overmolding by depositing a bonding primer or by overmolding a thin-layer plastic.

7. Tank (1) according to any one of the preceding claims, wherein the surface of the groove (5) is prepared for overmolding by plasma treatment.

8. Tank (1) according to any one of the preceding claims, where the neck (7) is assembled with the ring (8) by welding, preferably carried out by infrared or by hot gas, still preferably carried out by rotary friction.

9. Method for producing a tank (1) according to any one of the preceding claims comprising the following steps: - production and placement of the ring (8) in the groove (5) of the base (3) by overmolding, - assembly of the casing (6) by welding its neck (7) with the ring (8).

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