Pressurized gas storage tank with improved end piece

Abstract

The present invention relates to a liner (12) having a neck (14), a reinforcing jacket (18) covering the liner (12), and an end piece (20) provided within the neck (14), wherein the end piece (20) comprises: - an axial opening (22); a first annular projection (31) extending radially outward from the axial opening (22); a second annular projection (32) extending radially outward from the axial opening (22) and disposed axially outward relative to the first annular projection (31); an axially outer end (24) extending at least partially outside the tank (10); The present invention relates to a tank (10) including: The liner (12) extends from the first annular protrusion (31) to the second annular protrusion (32) while covering at least a portion of the first annular protrusion (31), and the tank (10) includes a sealing contact surface (SG) between the end piece (20) and the neck portion (14) extending between the first protrusion (31) and the second protrusion (32), and a contact surface (SE) between the end piece (20) and the reinforcing jacket (18) extending axially between the second protrusion (32) and the axial end (24).

Description

[Technical Field]

[0001] The present invention relates to pressurized gas storage tanks, particularly tanks for use in motor vehicles. More particularly, the present invention relates to pressurized gas storage tanks and methods for manufacturing pressurized gas storage tanks for gases such as, but not limited to, natural gas, biogas, liquefied petroleum gas, and hydrogen. [Background technology]

[0002] The various functions of this tank include: - contain pressurized gas, in other words have mechanical resistance; - ensuring tightness from the outside, - filling with pressurized gas using a solenoid valve attached to the end piece; - supplying pressurized gas using the same solenoid valve mounted on the end piece; - be fixed to a supporting structure; - withstand the conditions of transport and use; - Resistance to mechanical and thermal stresses from the external environment; - To withstand the manufacturing conditions of the tank Examples include:

[0003] These tanks can be mounted on any type of fixed or mobile equipment (vehicles used on roads, railroads, seas, air, and space). Tanks for pressurized gases are made of metallic materials, or more recently, composite materials for their weight and safety advantages.

[0004] Composite tanks, also known as composite tanks, are typically sealed by a container known as a "liner" that provides a seal against the contents. Tank manufacturers offer liners made from either metal or plastic materials.

[0005] "Plastic"-type liners include at least one opening for filling and draining the tank and are manufactured by injection molding, rotational molding, or extrusion blow molding of thermoplastic or thermosetting ("thermodurcissible" or "thermodur") polymer materials, such as polyethylene, polyamide, polyphthalamide, polyurethane, silicone, or polyoxymethylene. Advantageously, the thermoplastic polymer material contains reinforcing fibers to form a composite material. The reinforcing fibers are, for example, glass, carbon, basalt, aramid, polymer, silica, polyethylene, natural, metal, alloy, or ceramic fibers. These fibers increase the composite's resistance to deformation. In reinforcing polymer materials, the reinforcing fibers and polymer material are intertwined to form a monoblock material. This type of composite material is described by the applicant in French Patent Application No. 18 72197, filed November 30, 2018, and published under No. 3 089 160.

[0006] This liner is then covered with a composite liner reinforcement jacket, which forms the tank's main body, or in other words, its durable structure, and this structure must be able to withstand the pressure exerted by the fluid contained within the tank (hereinafter referred to as "internal pressure"). Normally, the reinforcement jacket is not required to ensure the tank's airtightness.

[0007] This reinforced jacket is - a reinforcement material usually composed of glass fibres, carbon fibres, basalt fibres or other fibres such as silica fibres or plant fibres, for example continuous fibres thereof; - Deposited simultaneously with the fibers (filament winding method) or with resin deposited after realizing the jacket to form a dry "preform" This dry preform is then reinforced to give it the required rigidity. This reinforcement is achieved by injecting resin, or by infiltrating the preform with this resin (infusion method), or by vacuum resin impregnation.

[0008] Advantageously, the reinforcing jacket is coated with one or more layers of a fire-resistant material, preferably a thermally expandable fire-resistant material, such as a silicate- or phosphate-based coating. Silicates and phosphates are thermal expansion agents that expand when exposed to fire, creating an insulating barrier, thereby increasing the tank's resistance to heat and fire.

[0009] In either case, during tank construction, an end piece is hermetically attached to the liner to allow filling and dispensing of the fluid. This end piece is usually made of metal (steel or aluminum). It fits over the fill / drain neck of the liner and has a flange that abuts against the liner. The end piece also has threads that allow a solenoid valve to be attached to the end piece. An end piece of this type is described in U.S. Pat. No. 6,230,922.

[0010] When a reinforcing jacket is deposited onto a liner by filament winding, the liner is held in place at the end pieces by a robotic arm or similar device. This can lead to several problems during the filament winding process. For clarity, filament winding involves wrapping a continuous layer of fiber around the liner in a helical fashion. When the fiber is wound at high speeds, the robotic arm exerts a large torque on the end pieces and their connections, especially during the acceleration and deceleration phases as the fiber layers are wound along the helical path. For polyamide 6 (PA6) liners, conventional screw connections between the end pieces and the liner can typically withstand a torque of up to 200–400 Nm, while liners made from high-density polyethylene (HDPE) are less durable. To increase tank production speeds, the torque resistance of the connections between the end pieces and the liner is required.

[0011] To improve this durability, it is known to increase the axial span of the liner neck where it is bonded to the end piece, thereby increasing the bonded area between the end piece and the liner neck. However, this increases the dead volume of the tank, meaning that the tank becomes bulkier at the liner neck location without increasing the amount of pressurized gas stored, which is undesirable given the limited space available inside the vehicle. To avoid this increase in dead volume of the tank, it is known to modify the liner geometry so that the liner neck is offset axially inward of the tank's internal volume. It is also known to modify the liner geometry so that the liner neck extends inside the tank's internal volume rather than outside it.

[0012] In both of the above cases, the axial size of the tank, i.e., its bulkiness, is reduced. However, this has the disadvantage of creating a recessed zone, commonly referred to as a "dead volume," around the base of the neck inside the tank. This recessed zone significantly complicates the measurement of the tank's mechanical resistance, which is performed in accordance with UN / ECE Regulation No. 134 on the Uniform Provisions for the Approval of Motor Vehicles and Their Components, for the safety of hydrogen-powered vehicles. This involves injecting pressurized fluid into the tank and measuring the tank's deformation. After this, the tank must be completely emptied of the used fluid. Emptying the inaccessible recessed zone is a very complicated and time-consuming process. Therefore, it is preferable to avoid the existence of recessed zones or at least minimize their volume. However, increasing the axial span of the neck of the liner, which is connected to the end piece, increases the volume of the recessed zone.

[0013] Another solution to improve durability is to inject adhesive between the end piece and the liner, but this is a time-consuming process that slows down tank manufacturing and makes inspection difficult.

[0014] U.S. Patent Application No. 2008251520, U.S. Patent Application No. 2007164561, WO 2018002788, and WO 2013008719 are known documents relating to a tank including a plastic liner, a neck surrounding an axial bore of the liner, a reinforcing jacket covering the liner, and an end piece including a first annular protrusion and an axially outer end, and the tank includes a sealing contact surface between the end piece and the reinforcing jacket extending between the first annular protrusion and the axial end of the end piece.

[0015] Also known is a tank according to EP 0810081, which includes a plastic liner, a neck surrounding an axial bore of the liner, a reinforcing jacket covering the liner, and an end piece including a first annular projection and an axially outer end. The tank further includes a packing disposed between the neck and a pressure element, which presses the packing against the end piece and the liner. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] French Patent Application No. 18 72197 [Patent Document 2] U.S. Patent No. 6,230,922 [Patent Document 3] U.S. Patent Application No. 2008251520 [Patent Document 4] U.S. Patent Application No. 2007164561 [Patent Document 5] International Publication No. 2018002788 [Patent Document 6] International Publication No. 2013008719 [Patent Document 7] European Patent No. 0810081 Summary of the Invention [Problem to be solved by the invention]

[0017] The primary objective of the present invention is to improve the durability of the end piece / liner joint and reduce damage to the liner when the tank is pressurized. Optimally, this improvement in the torque resistance of the end piece / liner joint can be achieved without increasing the bulk of the tank or slowing down the tank's manufacturing speed. [Means for solving the problem]

[0018] To this end, the present invention provides a pressurized gas storage tank comprising a generally cylindrical plastic liner extending along a major axis, the liner including a neck surrounding an axial bore of the liner, a reinforcing jacket covering the liner, and an end piece disposed at least partially within the neck and extending along the major axis, the end piece comprising: - an axial opening; a first annular projection extending radially outward from the axial opening of the tank; a second annular projection extending from the axial opening toward the radial outside of the tank, the second annular projection being disposed axially outside the tank relative to the first annular projection; an axially outer end portion extending at least partially outside the tank; and In a tank containing at least The present invention relates to a tank characterized in that the liner extends from the first annular protrusion to the second annular protrusion while covering at least a portion of the first annular protrusion, and the tank further includes a sealing contact surface between the end piece and a neck portion of the liner, extending between the first annular protrusion and the second annular protrusion, and a contact surface between the end piece and a reinforcing jacket, extending axially between the second annular protrusion and the axial end of the end piece.

[0019] An "annular projection" of an end piece means that portion of the end piece that extends radially from the end piece and extends beyond the end piece to include an axially open upper surface and an axially open lower surface.

[0020] The liner extends from the first annular protrusion (or the first fin) to the second annular protrusion (or the second fin), covering at least a portion of the first annular protrusion, thereby reducing the risk of liner degradation in the zone near the tank opening due to stresses exerted by the end piece on the liner during tank pressurization. A good seal at the tank opening is also ensured. Furthermore, the tank includes a sealing contact surface between the end piece and the liner neck, which extends between the first and second annular protrusions. This sandwiches the liner between the end piece and the reinforcing jacket in the zigzag contact zone, further reducing the risk of liner degradation in the zone near the tank opening. In fact, during tank pressurization, the end piece exerts both static and dynamic stresses on the liner neck. One example of liner degradation due to static stress is creep of the liner's plastic material at the neck. One example of degradation due to dynamic stress is fatigue of the liner's plastic material at the neck.

[0021] In addition to the risk of liner degradation mentioned above, the end pieces can deteriorate or even break if excessive pressure is applied to the tank, for example during the tank hydraulic cycle test specified in UN / ECE Regulation No. 134. This invention also reduces this risk.

[0022] Furthermore, by providing a direct contact surface between the end piece and the reinforcing jacket, extending axially between the second annular protrusion and the axial end of the end piece, a zone is formed further away from the tank opening, where, on the one hand, a good mechanical connection between the reinforcing jacket and the end piece is achieved, and, on the other hand, the liner is not sandwiched between the end piece and the reinforcing jacket. The presence of this type of zone reduces the risk of liner degradation due to the end piece and the reinforcing jacket. One example of liner degradation is shearing of the liner due to the end piece and the reinforcing jacket. Another example of liner degradation is creep of the liner's plastic material.

[0023] The invention thus has the advantage of reducing the risk of liner degradation in the zone of the tank opening, particularly due to shearing of the liner by the end piece and the reinforcing jacket, while reducing the risk of liner degradation at the end piece and the reinforcing jacket, thus increasing the durability of the joint between the end piece and the liner and avoiding liner failure during tank pressurization without increasing the bulk of the tank and without slowing down the tank's production speed.

[0024] According to a preferred embodiment, the neck of the liner extends from the axial bore of the liner toward the axial outside of the tank, thereby creating a contact surface between the neck of the liner and the reinforcing jacket that extends between the first and second annular projections. With this arrangement, the reinforcing jacket will absorb the stress that the end piece exerts on the neck of the liner when the tank is pressurized.

[0025] According to a preferred embodiment, the first annular projection is integral with the end piece, which on the one hand simplifies the manufacture of the tank while limiting the number of additional parts and avoiding fixations between these parts, and on the other hand ensures a better seal between the end piece and the liner.

[0026] According to a preferred embodiment, the second annular projection is also integral with the end piece, which on the one hand simplifies the manufacture of the tank while limiting the number of additional parts and avoiding fixation between these parts, and on the other hand ensures a better seal between the end piece and the liner.

[0027] According to a particular embodiment, the axially outer end of the end piece is not part of the second annular projection of the end piece, or vice versa, in other words they are not a zone or a direct extension of either, in which case the reinforcing jacket covers the entire second annular projection, which increases the contact surface between the end piece and the reinforcing jacket and ensures good mechanical contact between these two elements.

[0028] In an alternative embodiment, the axially outer end of the end piece is part of the second annular projection of the end piece, in which case the reinforcing jacket covers only part of the second annular projection.

[0029] Preferably, the axial end of the end piece is an annular projection in the above sense.

[0030] To further reduce the risk of deterioration of the liner and to further improve the sealing at the location of the tank opening, according to a particular embodiment the liner covers at least a portion of the second annular projection.

[0031] To further reduce the risk of liner deterioration and further improve sealing at the tank opening location, the liner covers the entire first annular protrusion.

[0032] Preferably, the contact surface between the end piece and the reinforcing jacket extends axially from the second annular projection to the axial end of the end piece, thereby increasing the contact surface between the end piece and the reinforcing jacket and ensuring good mechanical contact between these two elements.

[0033] According to a preferred embodiment, the maximum diameter of the first annular projection is equal to or less than the maximum diameter of the second annular projection, preferably strictly less than the maximum diameter of the second annular projection, thereby minimizing the size and weight of the end piece.

[0034] According to a particular embodiment, the maximum diameter of the first annular projection strictly exceeds the maximum diameter of the second annular projection, which increases the puncture resistance of the end piece during a hydraulic cycle test of the tank according to UN / ECE Regulation No. 134.

[0035] According to certain embodiments, the end piece further includes an axially inner end opposite the axially outer end and extending at least partially inside the tank, thereby maximizing the effective volume of the tank in constrained environments.

[0036] According to a specific embodiment, the end piece further includes a third annular protrusion (or a third fin) extending radially outward from the axial opening of the tank, the third annular protrusion being disposed axially outward of the tank relative to the second annular protrusion, thereby enabling the reinforcing jacket to more effectively bear the stress that the end piece exerts on the neck of the liner when the tank is pressurized.

[0037] According to a preferred embodiment, the third annular projection is also integral with the end piece, which on the one hand simplifies the manufacture of the tank while limiting the number of additional parts and avoiding fixation between these parts, and on the other hand ensures a better seal between the end piece and the liner.

[0038] According to a particular embodiment, the maximum diameter of the third annular projection is less than that of the second annular projection, which allows the weight of the end piece to be minimized.

[0039] According to a particular embodiment, the end piece further includes an annular shoulder extending from the axial opening radially outward of the tank, the annular shoulder being disposed axially outward of the tank relative to the third annular projection.

[0040] Preferably, the end piece further comprises an outer anchoring surface selected from the group consisting of a rough surface, a surface that is not rotationally symmetrical with respect to the main axis, an adhesive surface, and a combination of these surfaces, the outer anchoring surface of the end piece being the sealing contact surface between the end piece and the neck of the liner and / or the contact surface between the end piece and the reinforcing jacket. The presence of such an outer anchoring surface strengthens the mechanical bond between the end piece and the neck of the liner, thereby increasing the torque resistance of this bond. This allows for a rapid filament winding process with significant acceleration and deceleration phases, thus reducing the tank manufacturing time and manufacturing costs.

[0041] A surface that is not rotationally symmetrical with respect to a main axis means a surface whose cross section in a plane perpendicular to the main axis is not circular, in particular a surface with flat sections, such as a hexagonal, gear-shaped, striated, grooved, elliptical or other polygonal cross section.

[0042] The present invention also provides a method for manufacturing a pressurized gas storage tank, comprising the steps of: - providing an end piece extending along a main axis, the end piece including an axial opening, a first annular projection extending from the axial opening towards the radial outside of the tank, a second annular projection extending from the axial opening towards the radial outside of the tank, the second annular projection intended to be arranged axially outside of the tank with respect to the first annular projection, and an outer end intended to extend at least partially outside of the tank; - manufacturing a generally cylindrical liner extending along a major axis, the liner including a neck portion surrounding an axial bore of the liner; - securing the end piece to the liner such that the end piece is at least partially disposed within the neck portion of the liner and the neck portion extends along the major axis and provides a sealing interface between the end piece and the neck portion of the liner, the sealing interface extending between the first annular projection and the second annular projection; - securing a reinforcing jacket to the liner and the end piece, the reinforcing jacket covering the liner and creating a contact surface between the end piece and the reinforcing jacket extending axially between the second annular projection and the axial end of the end piece; The present invention also relates to a method for producing the same, comprising:

[0043] According to a particular embodiment, the liner is made of plastic, the end piece has an outer anchoring surface selected from the group consisting of a rough surface, a surface that is not rotationally symmetrical about a major axis, an adhesive surface, and a combination of these surfaces, and the step of fixing the end piece to the liner includes a step of overmolding the neck of the liner onto the outer anchoring surface of the end piece during the step of manufacturing the liner, the liner being preferably manufactured by extrusion blow molding, which facilitates the manufacturing of the tank. The presence of the adhesive surface improves the sealing of the sealing contact surface between the end piece and the neck of the liner, among other things.

[0044] According to another particular embodiment, the liner is made of plastic and the end piece comprises an outer anchoring surface selected from the group consisting of a rough surface, a surface that is not rotationally symmetrical about a major axis, an adhesive surface and combinations of these surfaces, and the step of fixing the end piece to the liner comprises the following steps: - overmolding an intermediate layer of plastic material, chemically compatible with the plastic material of the liner, onto the outer anchoring surface of the end piece, the intermediate layer preferably being manufactured by injection molding; - during the step of manufacturing the liner, overmolding the neck portion of the liner onto an intermediate layer of plastic material, the liner being preferably manufactured by extrusion blow molding; Includes:

[0045] By "chemically compatible," it is meant that the first and second polymeric materials each contain chemical species that allow them to weld together without the need for additional materials. In other words, chemically compatible polymeric materials can be intimately bonded together by fusion, particularly by achieving intermolecular entanglement of polymer chains between them. This type of intermolecular entanglement can be created by heating the contact points.

[0046] Preferably, the roughened surface of the end piece is obtained by a step selected from the group consisting of etching the outer anchoring surface of the end piece, machining the outer anchoring surface of the end piece, shaping the outer anchoring surface of the end piece, knurling the outer anchoring surface of the end piece, and combinations of these steps; the surface that is not rotationally symmetrical about the major axis of the end piece is obtained by machining and / or shaping the outer anchoring surface of the end piece; and the adhesive surface of the end piece is obtained by depositing an adhesive on the outer anchoring surface of the end piece or activating the outer anchoring surface of the end piece. Etching of the outer anchoring surface of the end piece can be performed, for example, using an etchant or a laser. Deposition of the adhesive on the adhesive surface of the end piece can be performed by spraying or injection molding. Activation of the outer anchoring surface of the end piece can be performed by plasma, laser, or heating. Activation changes the surface tension of the outer anchoring surface of the end piece, generating free radicals on this surface, which can form covalent or van der Waals bonds with the plastic material of the liner, thereby improving mutual adhesion.

[0047] Preferably, the reinforcing jacket is made of a composite material including a resin and reinforcing fibers, and the step of fixing the reinforcing jacket to the end piece and liner is a step of filament winding the reinforcing jacket onto the liner and end piece during the step of manufacturing the reinforcing jacket.

[0048] The invention will be better understood from a reading of the following description, given by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0049] [Figure 1] 1 is a partial cross-sectional view along the mid-plane of a connection zone of a pressurized gas storage tank according to a first embodiment of the present invention; FIG. [Figure 2] FIG. 2 is a cross-sectional view taken along plane II-II of FIG. [Figure 3] FIG. 2 is a perspective view of an end piece of the tank of FIG. 1. [Figure 4] FIG. 4 is a bottom view of the end piece of FIG. 3. [Figure 5] 10 is a partial cross-sectional view along the mid-plane of a connection zone of a pressurized gas storage tank according to a second embodiment of the present invention; FIG. [Figure 6] 10 is a partial cross-sectional view taken along the mid-plane of a connection zone of a pressurized gas storage tank according to a third embodiment of the present invention. FIG. [Figure 7] 10 is a partial cross-sectional view taken along the mid-plane of a connection zone of a pressurized gas storage tank according to a fourth embodiment of the present invention; FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along plane VIII-VIII of FIG. 7. [Figure 9] FIG. 8 is a perspective view of the end piece of the tank of FIG. [Figure 10] FIG. 10 is a bottom view of the end piece of FIG. 9. [Figure 11] FIG. 10 is a partial cross-sectional view along the mid-plane of a connection zone of a pressurized gas storage tank according to a fifth embodiment of the present invention. [Figure 12] FIG. 12 is a cross-sectional view taken along plane XII-XII of FIG. 11. [Figure 13] FIG. 12 is a perspective view of the end piece of the tank of FIG. 11. [Figure 14] FIG. 14 is a bottom view of the end piece of FIG. 13. [Figure 15] 10 is a partial cross-sectional view taken along the mid-plane of a connection zone of a pressurized gas storage tank according to a sixth embodiment of the present invention. FIG. [Figure 16] FIG. 16 is a cross-sectional view taken along plane XVI-XVI of FIG. 15. [Figure 17] FIG. 16 is a perspective view of the end piece of the tank of FIG. [Figure 18] FIG. 18 is a bottom view of the end piece of FIG. 17. DETAILED DESCRIPTION OF THE INVENTION

[0050] A portion of a pressurized gas storage tank 10 according to a first embodiment of the present invention is shown in Figure 1. The tank 10 includes a plastic liner 12 that defines an interior volume V of the pressurized gas storage tank.

[0051] Here, the liner 12 has a generally cylindrical or tubular central portion, referenced to the main axis XX of the tank 10, and two ends, one of which is shown in Figure 1. The end of the liner 12 shown includes a neck portion 14 surrounding an axial bore 16 in the liner 12 that connects the tank's internal volume V with the external environment, the neck portion 14 extending outside the internal volume V. The liner 12 is preferably manufactured by injection molding, rotational molding or extrusion blow molding of a thermoplastic or thermosetting polymer material, such as polyamide or polyethylene, and the liner 12 has a thickness of, for example, 5 mm or less.

[0052] The tank 10 further comprises a reinforcing jacket 18, preferably made of composite material, surrounding the liner 12, which constitutes the body of the tank 10, in other words the durable structure of the tank 10.

[0053] The reinforcing jacket 18 preferably comprises a reinforcement material made of glass, carbon, basalt or other fibers, such as silica or plant fibers, e.g. continuous fibers thereof, and a resin that is either deposited simultaneously with the fibers (e.g. by filament winding) or deposited after realization of the jacket to form a dry "preform" that is then reinforced to give it the required stiffness. This reinforcement is achieved by injection of resin or by infiltrating the preform with this resin (infusion method) or by vacuum resin impregnation.

[0054] Advantageously, the reinforcing jacket 18 is coated with one or more layers of a fire-resistant material, preferably a thermally expandable fire-resistant material, such as a silicate- or phosphate-based coating. Silicates and phosphates are thermally expandable agents that expand upon exposure to fire to create an insulating barrier, thereby increasing the tank's resistance to heat and fire.

[0055] The tank 10 further includes an end piece 20 disposed at least partially within the neck 14 of the liner 12. The end piece 20 has a generally rotationally symmetrical shape about a main axis XX. The end piece 20 includes a central portion that extends partially within the neck 14 of the liner 12 and a peripheral portion that extends partially around the neck 14 of the liner 12, such that the neck 14 of the liner 12 is protected from the external environment by the end piece 20. The end piece 20 is a metallic, e.g., aluminum, part. The end piece 20 is configured to accommodate, among other things, a solenoid valve (not shown) that allows the tank 10 to be alternately filled and emptied of gas.

[0056] In all the illustrated embodiments, the tank 10 further includes a sealing interface SG between the end piece 20 and the neck 14 of the liner.

[0057] The end piece 20 extends along the main axis XX and is at least partially disposed within the neck portion 14. The end piece includes an axial opening 22, for example of substantially circular cross section, extending along the main axis XX.

[0058] 1 and 3, the end piece 20 further includes an axially outer end 24 that extends at least partially outside the tank 10. Here, the adjective "outside" is understood relative to the volume V of the tank 10. That is, the axially outer end 24 is located outside the liner neck 14 and is not covered by the reinforcing jacket 18. The axially outer end 24 includes an annular shoulder 26 that extends from the axial opening 22 radially outward of the tank.

[0059] The end piece 20 further includes an axially inner end 28 opposite the axially outer end 24 and extending at least partially inside the tank 10. Here, the adjective "inside" is understood with respect to the volume V of the tank 10. That is, the axially inner end 28 is located outside the liner neck 14 and is not covered by the reinforcing jacket 18. The axially inner end is located within the volume V of the tank 10.

[0060] The end piece 20 further includes a first annular protrusion 31, or first fin 31, that extends radially outward from the axial opening 22 of the tank 10, where the first annular protrusion 31 is integral with the end piece 20. The "annular protrusion" of the end piece 20 refers to the portion of the end piece 20 that extends radially from the end piece 20 and extends beyond the end piece 20 to include an axially open upper surface and an axially open lower surface.

[0061] In each of the illustrated embodiments, the axially outer end 24 is specifically a protrusion within the meaning of this definition, although as will be explained below, this is only one embodiment.

[0062] The first annular projection 31 preferably exhibits radial symmetry about the main axis XX, and its radial profile is preferably a continuous curve, in other words it does not contain any sharp corners.

[0063] Preferably, the end piece 20 further comprises an outer anchoring surface SA selected from the group comprising rough surfaces, surfaces that are not rotationally symmetrical about the main axis XX, adhesive surfaces and combinations of these surfaces.

[0064] A surface that is not rotationally symmetrical with respect to the main axis XX means a surface whose cross section in a plane perpendicular to the main axis XX is not circular, in particular a surface with flat sections, such as a cross section with a polygonal contour, e.g. hexagonal, gear-shaped, striated, grooved, elliptical, etc.

[0065] The presence of such an outer anchoring surface SA strengthens the mechanical joint between the end piece 20 and the neck 14 of the liner 12, thereby increasing the torque resistance of this joint.

[0066] In the first three embodiments shown in Figures 1 to 6, the first annular projection 31 has an outer anchoring surface SA of this kind, which is a surface that is not rotationally symmetrical with respect to the main axis XX.

[0067] Indeed, in these first three embodiments, the outer anchoring surface SA, as can be seen in particular in Figures 2 to 4, has locally a gear-shaped cross section along a plane perpendicular to the axis XX (in this case the section II-II); in other words, the outer anchoring surface comprises a plurality of teeth 29 projecting from a first annular projection 31 extending radially outward of the tank 10. Preferably, the teeth 29 are distributed symmetrically around the axis XX. The number of gear teeth 29 is here 12, although this number may of course vary. The shape of the teeth 29 is also substantially rectangular in this plane II-II, although this may also vary.

[0068] Thus, in these first three embodiments, the outer anchoring surface SA is formed by a series of recesses (spaces between each tooth 29) and protrusions (each tooth 29), thus strengthening the mechanical connection between the end piece 20 and the neck portion 14 of the liner 12 and thereby increasing the torque resistance of this connection.

[0069] Here, the outer anchoring surface SA forms part of the sealing contact surface SG between the neck 14 and the end piece 20, but it is also conceivable that it forms the entire sealing contact surface SG. The ratio between the outer anchoring surface SA and the sealing contact surface SG between the end piece 20 and the neck 14 may of course be varied as required.

[0070] The end piece 20 further includes a second annular protrusion 32, or a second fin 32, extending from the axial opening 22 toward the radially outer side of the tank 10. The second annular protrusion 32 is disposed axially outward of the tank 10 relative to the first annular protrusion 31, in other words, disposed upward in each of the drawings relative to the first annular protrusion 31. Here, the second annular protrusion 32 is integral with the end piece 20.

[0071] In each of the illustrated embodiments, the axially outer end 24 of the end piece is not part of the second annular projection 32 of the end piece, and vice versa; in other words, they are not a zone or a direct extension of either. In this case, the reinforcing jacket 18 covers the entire second annular projection 32, which increases the contact surface between the end piece 20 and the reinforcing jacket 18 and ensures good mechanical contact between these two elements.

[0072] However, in an alternative embodiment not shown, the axially outer end 24 of the end piece is part of the second annular projection 32 of the end piece. In this case, the reinforcing jacket 18 covers only a portion of the second annular projection 32.

[0073] The second annular projection 32 preferably exhibits radial symmetry about the main axis XX. Its radial profile is preferably a continuous curve, in other words it does not contain any sharp corners. In all the embodiments shown, its cross section along a plane perpendicular to the axis XX is substantially circular. Of course, the shape of the second annular projection 32 may vary.

[0074] In the first embodiment of the invention shown in FIGS. 1 to 4, the maximum diameter D1 of the first annular projection 31 strictly exceeds the maximum diameter D2 of the second annular projection 32.

[0075] However, according to the second embodiment of the present invention shown in Figure 5, the maximum diameter D1 of the first annular protrusion 31 is substantially the same as the maximum diameter D2 of the second annular protrusion 32. The tank 10 is the same as that of the first embodiment.

[0076] According to a third embodiment of the present invention shown in Figure 6, the maximum diameter D1 of the first annular protrusion 31 is equal to or smaller than the maximum diameter D2 of the second annular protrusion 32, preferably strictly smaller than the maximum diameter D2 of the second annular protrusion 32. The tank 10 is the same as that of the first embodiment.

[0077] In all the illustrated embodiments, the sealing contact surface SG between the end piece 20 and the liner neck 14 extends between the first annular projection 31 and the second annular projection 32, as can be seen in Figures 1, 5, 7, 11 and 15.

[0078] According to a specific embodiment, the end piece further includes a third annular protrusion (or third fin) 33 extending from the axial opening 22 toward the radially outer side of the tank 10. The third annular protrusion 33 is disposed axially outward of the tank 10 relative to the second annular protrusion 32, in other words, upward in the figures relative to the second annular protrusion 32. Here, the third annular protrusion 33 is integral with the end piece 20.

[0079] The third annular projection 33 preferably exhibits radial symmetry about the main axis XX. Its radial profile is preferably a continuous curve, in other words it does not contain any sharp corners. In all the embodiments shown, its cross section along a plane perpendicular to the axis XX is substantially circular. Of course, the shape of the third annular projection 33 may vary.

[0080] In all illustrated embodiments, the maximum diameter D3 of the third annular projection 33 is less than that of the second annular projection 32, as seen in Figures 1, 5, 7, 11 and 15. However, this diameter can be varied as desired.

[0081] In all the illustrated embodiments, the tank 10 further includes a contact surface SE between the end piece 20 and the reinforcing jacket 18, which extends axially between the second annular projection 32 and the axially outer end 24 of the end piece 20, as can be seen in Figures 1, 5, 7, 11 and 15.

[0082] In all of the illustrated embodiments, the neck 14 of the liner 12 extends from the axial bore 16 of the liner 12 axially outwardly of the tank 10, thereby creating an interface between the neck 14 of the liner 12 and the reinforcing jacket 18 that extends between the first annular projection 31 and the second annular projection 32.

[0083] In all the illustrated embodiments, the liner 12 extends from the first annular protrusion 31 to the second annular protrusion 32, covering at least a portion of the first annular protrusion 31, as can be seen in Figures 1, 5, 7, 11 and 15. This further reduces the risk of deterioration of the liner 12 in the zone near the opening of the tank 10 due to the stresses that the end piece 20 exerts on the liner when the tank 10 is pressurized, and also ensures good sealing at the opening of the tank 10.

[0084] To further reduce the risk of deterioration of the liner 12 and to further improve the sealing at the opening of the tank 10, in all illustrated embodiments the liner 12 covers at least a portion of the second annular projection 32, as can be seen in Figures 1, 5, 7, 11 and 15.

[0085] To further reduce the risk of deterioration of the liner 12 and to further improve the sealing at the opening of the tank 10, in all illustrated embodiments the liner 12 covers the entire first annular protrusion, as can be seen in Figures 1, 5, 7, 11 and 15.

[0086] Preferably, the contact surface SE between the end piece 20 and the reinforcing jacket 18 extends axially from the second annular projection to the axial end of the end piece 20. In this way, the contact surface SE between the end piece 20 and the reinforcing jacket 18 can be increased to ensure good mechanical contact between these two elements.

[0087] In an alternative embodiment not shown, the outer anchoring surface SA forms part of the contact surface SE between the end piece 20 and the reinforcing jacket 18 or the entire contact surface SE between the end piece 20 and the reinforcing jacket 18. In yet another alternative embodiment not shown, the end piece 20 comprises two outer anchoring surfaces SA which form part of or the entire sealing contact surface SG between the neck portion 14 of the liner 12 and the end piece 20 and the contact surface SE between the end piece 20 and the reinforcing jacket 18, respectively.

[0088] In the fourth embodiment shown in Figures 7 to 10, the first annular projection 31 has a hexagonal cross section along a plane perpendicular to the main axis XX (in this case the plane of its greatest diameter, i.e. the plane VIII-VIII).

[0089] Thus, the first annular projection 31 has six substantially flat faces 34 symmetrically distributed around the main axis XX, as can be seen in Figures 8 and 10, which together form an outer anchoring surface SA that is not rotationally symmetric with respect to the main axis XX.

[0090] In a fifth embodiment shown in Figures 11 to 14, the first annular projection 31 comprises a plurality of transverse notches 36 on its periphery. Here, the transverse notches 36 have a T-shaped cross section in a plane perpendicular to the main axis XX (in this case in the plane of its greatest diameter, here the plane XII-XII), as can be seen in Figure 14. When the end piece 20 is viewed from the side, as in Figure 13, the transverse notches 36 have the shape of a capital letter "I". The transverse notches 36 are preferably distributed symmetrically around the axis XX. Their number is, for example, nine, although this may of course vary.

[0091] The first annular projection 31 thus has an outer anchoring surface SA that is not rotationally symmetrical with respect to the main axis XX.

[0092] In the sixth embodiment shown in Figures 15 to 18, the first annular projection 31 has an elliptical cross section along a plane perpendicular to the main axis XX (in this case the plane of its greatest diameter, i.e. the plane XVI-XVI).

[0093] Thus, the first annular projection 31 has ellipsoidal surfaces 38, as can be seen in Figures 16 and 18, which together form an outer anchoring surface SA that is not rotationally symmetrical with respect to the main axis XX.

[0094] An example of a method for manufacturing the tank 10 will now be described.

[0095] In a first step, an end piece such as the end piece 20 is provided, that is to say an end piece extending along a main axis XX, comprising an axial opening 22, a first annular protrusion 31 extending from the axial opening 22 towards the radial outside of the tank 10, a second annular protrusion 32 extending from the axial opening 22 towards the radial outside of the tank 10, the second annular protrusion 32 intended to be arranged axially outside the tank 10 relative to the first annular protrusion 31, and an outer end 24 intended to extend at least partially outside the tank 10.

[0096] If the end piece 20 includes an outer anchoring surface SA that includes a roughened surface, the roughened surface can be obtained by a step selected from the group consisting of etching the outer anchoring surface SA of the end piece, machining the outer anchoring surface of the end piece, molding the outer anchoring surface SA, knurling the outer anchoring surface SA of the end piece, and a combination of these steps; the surface that is not rotationally symmetrical about the main axis XX of the end piece can be obtained by machining and / or molding the outer anchoring surface SA of the end piece, and the end piece adhesive surface can be obtained by depositing an adhesive on the outer anchoring surface SA of the end piece or activating the outer anchoring surface SA of the end piece. Etching the outer anchoring surface SA of the end piece can be performed, for example, using an etchant or a laser. Deposition on the adhesive surface of the end piece can be performed by spraying or injection molding. Activation of the outer anchoring surface SA of the end piece can be performed by plasma, laser, or heating.

[0097] Next, a generally cylindrical liner 12 is fabricated extending along an axis XX, the liner 12 including a neck portion 14 surrounding an axial bore 16 in the liner 12. The liner 12 is made of, for example, plastic and is preferably fabricated by extrusion blow molding.

[0098] The end piece 20 is then fixed to the liner 12 so that the end piece 20 is at least partially disposed within the neck 14 of the liner 12 and so that the neck 14 extends along the main axis XX and so that a sealing contact surface SG between the end piece 20 and the neck 14 of the liner 12 extends between the first annular projection 31 and the second annular projection 32. This step of fixing the end piece 20 to the liner 12 may include, inter alia, overmolding the neck 14 of the liner 12 onto the end piece outer anchoring surface SA during a manufacturing step of the liner 12.

[0099] In an alternative embodiment, the end piece 20 is fixed to the liner 12 by overmolding an intermediate layer of plastic material that is chemically compatible with the plastic material of the liner 12 onto the outer anchoring surface SA of the end piece 20, the intermediate layer preferably being manufactured by injection molding, and by overmolding the neck portion 14 of the liner 12 onto the intermediate layer of plastic material during the manufacturing step of the liner 12.

[0100] Next, the reinforcing jacket 18 is fixed to the liner 12 and the end piece 20 so that the reinforcing jacket 18 covers the liner 12 and creates a contact surface SE between the end piece 20 and the reinforcing jacket 18 that extends axially between the second annular protrusion 32 and the axially outer end 24 of the end piece 20. Preferably, the reinforcing jacket 18 is made of a composite material including a resin and reinforcing fibers.

[0101] Also preferably, the reinforcing jacket 18 is secured to the end pieces 20 and liner 12 during the manufacturing step of the reinforcing jacket 18, by filament winding the reinforcing jacket 18 onto the liner and end pieces 20.

[0102] The present invention is not limited to the embodiments presented, and other embodiments will be apparent to those skilled in the art. In particular, it is conceivable that the maximum diameters of the first, second, and third annular protrusions in the fourth, fifth, and sixth embodiments may be changed in the same manner as in the first, second, and third embodiments. [Explanation of symbols]

[0103] 10 Tank 12 Liner 14 Neck 16 Liner axial hole 18 Reinforced jacket 20 End Piece 22 Axial opening of end piece 24 Axial outer end of end piece 26 Annular shoulder of end piece 28 Axial inner end of end piece 29 First annular protrusion teeth 31 first annular protrusion of end piece 32 second annular protrusion of end piece 33 Third annular protrusion of end piece 34 Hexagonal Faces 36 Lateral notch 38 Elliptical Surface D1 Maximum diameter of the first annular protrusion D2 Maximum diameter of second annular protrusion D3 Maximum diameter of the third annular protrusion V-tank internal volume SA End piece outer mooring surface Contact surface between SE end piece and reinforcing jacket SG Sealed contact surface between neck and end piece XX Tank Main Axis

Claims

1. 1. A pressurized gas storage tank (10) comprising: a generally cylindrical plastic liner (12) extending along a major axis (XX), the liner (12) including a neck (14) surrounding an axial bore (16) of the liner (12); a reinforcing jacket (18) covering the liner (12); and an end piece (20) disposed at least partially within the neck (14) and extending along the major axis (XX), the end piece (20) comprising: - an axial opening (22); a first annular projection (31) extending from the axial opening (22) toward the radial outside of the tank (10); a second annular projection (32) extending from the axial opening (22) toward the radially outer side of the tank (10), the second annular projection (32) being disposed axially outward of the tank (10) relative to the first annular projection (31); an axially outer end (24) extending at least partially outside the tank (10); In a tank (10) containing at least The tank (10) is characterized in that the liner (12) extends from the first annular protrusion (31) to the second annular protrusion (32) while covering at least a portion of the first annular protrusion (31), and the tank (10) further includes a sealing contact surface (SG) between the end piece (20) and the neck portion (14) of the liner (12) extending between the first annular protrusion (31) and the second annular protrusion (32), and a contact surface (SE) between the end piece (20) and the reinforcing jacket (18) extending axially between the second annular protrusion (32) and the axial end (24) of the end piece (20).

2. 2. The tank (10) of claim 1, wherein the neck portion (14) of the liner (12) extends from the axial bore (16) of the liner (12) axially outwardly of the tank (10).

3. 3. The tank (10) of claim 1 or 2, wherein the liner (12) covers at least a portion of the second annular projection (32).

4. 4. The tank (10) according to any one of claims 1 to 3, wherein the liner (12) covers the entire first annular projection (31).

5. 5. The tank (10) according to claim 1, wherein the contact surface (SE) between the end piece (20) and the reinforcing jacket (18) extends axially from the second annular protrusion (32) to the axially outer end (24) of the end piece (20).

6. 6. The tank (10) according to any one of claims 1 to 5, wherein the maximum diameter of the first annular protrusion (31) is equal to or less than the maximum diameter of the second annular protrusion (32), preferably strictly less than the maximum diameter of the second annular protrusion (32).

7. 6. The tank (10) according to any one of claims 1 to 5, wherein the maximum diameter of the first annular projection (31) strictly exceeds the maximum diameter of the second annular projection (32).

8. 8. The tank (10) according to any one of claims 1 to 7, wherein the end piece (20) further includes a third annular protrusion (33) extending from the axial opening (22) toward the radially outer side of the tank (10), the third annular protrusion (33) being disposed axially outward of the tank (10) relative to the second annular protrusion (32).

9. 9. The tank (10) according to claim 1, wherein the end piece (20) further comprises an outer anchoring surface (SA) selected from the group consisting of roughened surfaces, surfaces that are not rotationally symmetrical with respect to the main axis (XX), adhesive surfaces, and combinations of these surfaces, and the end piece outer anchoring surface (SA) is a sealing contact surface (SG) between the end piece (20) and the neck portion (14) of the liner (12) and / or a contact surface (SE) between the end piece (20) and the reinforcing jacket (18).

10. A method of manufacturing a pressurized gas storage tank (10) comprising the steps of: - providing an end piece (20) extending along a main axis (XX), the end piece (20) including an axial opening (22), a first annular projection (31) extending from the axial opening (22) towards the radial outside of the tank (10), a second annular projection (32) extending from the axial opening (22) towards the radial outside of the tank (10) and intended to be arranged axially outside of the tank (10) with respect to the first annular projection (31), and an axially outer end (24) intended to extend at least partially outside of the tank (10); - manufacturing a generally cylindrical liner (12) extending along said major axis (XX), said liner including a neck portion (14) surrounding an axial bore (16) of said liner (12); - fixing the end piece (20) to the liner (12), the end piece (20) being at least partially disposed within the neck portion (14) of the liner (12) and so as to create a sealing contact surface (SG) between the end piece (20) and the neck portion (14) of the liner (12), the neck portion (14) extending along the main axis (XX) and between the first annular projection (31) and the second annular projection (32); - fixing a reinforcing jacket (18) to the liner (12) and the end piece (20), so that the reinforcing jacket (18) covers the liner (12) and creates a contact surface (SE) between the end piece (20) and the reinforcing jacket (18) that extends axially between the second annular projection (32) and the axial end (24) of the end piece (20); A manufacturing method comprising:

11. 11. The method according to claim 10, wherein the liner (12) is made of plastic, the end piece (20) comprises an outer anchoring surface (SA) selected from the group consisting of a rough surface, a surface that is not rotationally symmetrical with respect to the main axis (XX), an adhesive surface, and combinations of these surfaces, and the step of fixing the end piece (20) to the liner (12) comprises a step of overmolding the neck portion (14) of the liner (12) onto the end piece outer anchoring surface (SA) during a manufacturing step of the liner (12), the liner (12) being preferably manufactured by extrusion blow molding.

12. The liner (12) is made of plastic, the end piece (20) comprises an outer anchoring surface (SA) selected from the group consisting of a rough surface, a surface that is not rotationally symmetrical with respect to the main axis (XX), an adhesive surface and a combination of these surfaces, and the step of fixing the end piece (20) to the liner (12) comprises the following steps: - overmolding an intermediate layer of plastic material, chemically compatible with the plastic material of the liner (12), onto the end piece outer anchoring surface (SA), said intermediate layer being preferably manufactured by injection molding; - during the manufacturing step of the liner (12), overmolding the neck portion (14) of the liner (12) onto the intermediate layer of plastic material, the liner (12) being preferably manufactured by extrusion blow molding; 11. The method of claim 10, comprising:

13. 13. The method according to claim 11 or 12, wherein the rough surface of the end piece (20) is obtained by a step selected from the group consisting of etching the end piece outer anchoring surface (SA), machining the end piece outer anchoring surface (SA), shaping the end piece outer anchoring surface (SA), knurling the end piece outer anchoring surface (SA) and combinations of these steps, wherein the surface of the end piece that is not rotationally symmetrical with respect to the main axis (XX) of the end piece is obtained by machining and / or shaping the end piece outer anchoring surface (SA), and wherein the end piece adhesive surface is obtained by depositing an adhesive on the end piece outer anchoring surface (SA) or activating the end piece outer anchoring surface (SA).

14. 14. The method according to claim 10, wherein the reinforcing jacket (18) is made of a composite material including a resin and reinforcing fibers, and the step of fixing the reinforcing jacket (18) to the end piece (20) and the liner (12) is a step of filament winding the reinforcing jacket (18) around the liner (12) and the end piece (20) during a manufacturing step of the reinforcing jacket (18).

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