Vessel for containing a pressurised gas with improved endpiece

Abstract

The invention relates to a vessel (10) comprising a liner (12) having a neck (14), a reinforcing shell (18) covering the liner (12), and an endpiece (20) arranged in the neck (14), which comprises: - an axial opening (22); - a first annular projection (31) extending radially outwards with respect to the axial opening (22); - a second annular projection (32) extending radially outwards with respect to the axial opening (22), arranged axially outwards with respect to the first projection (31); and - an outer axial end (24) extending at least partially outside the vessel (10). The liner (12) extends from the first annular projection (31) to the second annular projection (32) covering at least one portion of the first annular projection (31) and the vessel (10) comprises a sealed contact surface (SG) between the endpiece (20) and the neck (14) extending between the first projection (31) and the second projection (32), as well as a contact surface (SE) between the endpiece (20) and the reinforcing shell (18), which extends axially between the second projection (32) and the outer axial end (24).

Description

Tank intended to contain a pressurized gas with an improved nozzle

[0001] The invention relates to tanks intended to contain pressurized gases, in particular tanks installed in motor vehicles. The invention relates more specifically to a tank intended to contain a pressurized gas and to a method for manufacturing a tank intended to contain a pressurized gas. The gases in question are, for example, and not limited to, natural gas, biogas, liquefied petroleum gas, hydrogen.

[0002] The different functions of these tanks are:

[0003] - contain the gas under pressure, i.e. resist mechanically,

[0004] - ensure watertightness from the outside,

[0005] - ensure filling with pressurized gas, using a solenoid valve mounted on the nozzle,

[0006] - deliver the pressurized gas using the same solenoid valve mounted on the nozzle,

[0007] - attach to the supporting structure,

[0008] - withstand transport and use conditions,

[0009] - resist external environmental, mechanical and thermal aggressions,

[0010] - withstand the manufacturing conditions of the tanks.

[0011] These tanks can be mounted on any fixed or mobile equipment (vehicles on road, rail, sea, air, space). Pressurized gas tanks are made of metallic materials or, more recently, of composite materials, for reasons of weight saving and safety.

[0012] As for composite tanks, their sealing is generally achieved by installing a container called a "liner" capable of ensuring the container's sealing with respect to the contents. Depending on the tank manufacturer, liners are available in metallic or plastic materials.

[0013] The "plastic" type liner includes at least one opening for filling and emptying the tank. It is manufactured by injection or rotational molding or by extrusion-blow molding of a thermoplastic or thermosetting polymer material (abbreviated as "thermodur") such as, for example, polyethylene, polyamide, polyphthalamide, polyurethane, silicone, polyoxymethylene. Advantageously, the thermoplastic polymer material is loaded with reinforcing fibers to form a composite material. The reinforcing fibers are, for example, glass fibers, carbon fibers, basalt fibers, aramid fibers, polymer fibers, silica fibers, polyethylene fibers, natural fibers, metal fibers, metal alloy fibers or ceramic fibers. These fibers make it possible to increase the resistance to deformation of the composite material.In a polymer material loaded with reinforcing fibers, the reinforcing fibers and the polymer material are entangled to form a single-piece material. Such a composite material is described by the Applicant in its French patent application No. 18 72197 filed on November 30, 2018 and published under No. 3,089,160.

[0014] This liner is then covered with a liner reinforcement envelope made of composite material which will constitute the body of the tank, i.e. the resistant structure of the tank, which must be able to withstand the pressures exerted by the fluid contained in the tank (hereinafter referred to as "internal pressure"). The reinforcement envelope is generally not required to ensure the watertightness of the tank.

[0015] This reinforcement envelope is made up of:

[0016] - a reinforcement generally made up of fibers, for example continuous, of glass, carbon, basalt, or others such as silica fibers or even plant fibers,

[0017] - a resin which is either deposited at the same time as the fiber (filament winding process) or after the envelope has been made to constitute a dry “preform”. This dry preform is then consolidated in order to give it the necessary rigidity. This consolidation is carried out using a resin injection or by infiltration of this resin through the said preform (infusion process), or by means of vacuum resin impregnation.

[0018] Advantageously, the reinforcing shell is coated with one or more layers of a fire-retardant material, preferably an intumescent fire-retardant material such as, for example, a silicate or phosphate-based coating. Silicate and phosphate are intumescent agents which, after exposure to fire, expand and create an insulating barrier. This improves the heat and fire resistance of the tank.

[0019] In all cases, at the time of manufacturing the tank, a nozzle is assembled to seal the liner to allow filling and delivery of the fluid. This nozzle is generally made of metal (steel or aluminum). It is attached to a filling / emptying neck of the liner and has a collar for bearing against the liner. The nozzle also has a thread allowing a solenoid valve to be mounted on the nozzle. Such a nozzle is described in patent document US6230922.

[0020] When the reinforcing jacket is applied to the liner by a filament winding process, the liner is held by a robot arm or similar device at the tip. This can pose certain problems during the implementation of the filament winding process. It is recalled that the filament winding process consists of applying successive layers of fibers wound helically and circumferentially onto the liner. If the filament winding is carried out at a high speed, a significant torque is applied by the robot arm to the tip and to the connection between the tip and the liner, particularly during acceleration or deceleration phases that occur when applying layers of fibers wound along a helical trajectory.With a liner made of polyamide 6 (PA6), a conventional screw connection between the end piece and the liner generally allows a resistance to a maximum torque of between 200 and 400 Nm to be obtained; this resistance is lower with a liner made of high-density polyethylene (HDPE). In order to accelerate the manufacturing speed of the tank, it is necessary to increase the torque resistance of the connection between the end piece and the liner.

[0021] In order to increase this resistance, it is known to increase the axial span of the neck of the liner connected to the end piece, in order to increase the connection surface between the end piece and the neck of the liner. However, this results in an increase in the non-useful volume of the tank, i.e. the bulk of the tank is increased without increasing its capacity to store pressurized gas, at the neck of the liner, which is desirable to avoid due to the limited space available in the vehicle. To prevent the increase in the non-useful volume of the tank, it is known to change the shape of the liner so that the neck of the liner is axially offset towards the inside of the internal volume of the tank. It is also known to change the shape of the liner so that the neck of the liner extends towards the inside of the internal volume of the tank and not towards the outside of the internal volume of the tank.

[0022] In both of the above cases, the axial dimension of the tank is reduced and therefore the tank's bulk. However, this comes with a drawback, in that it creates a concave area inside the tank around the base of the neck, generally called "dead volume". The presence of this concave area considerably complicates the process for measuring the mechanical strength of the tank, carried out according to Regulation No. 134 of the United Nations Economic Commission for Europe (UNECE) concerning uniform provisions for the approval of motor vehicles and their components with regard to the safety requirements for hydrogen-powered vehicles, according to which pressurized fluid is injected inside the tank and the deformation of the tank is measured. After implementing this process, it is necessary to completely empty the tank of the fluid used.Emptying the concave area, which is difficult to access, is a particularly complex and time-consuming step, so it is preferable to avoid the presence of the concave area, or at least to reduce the volume of the concave area as much as possible. However, an increase in the axial span of the liner neck connected to the nozzle leads to an increase in the volume of the concave area.

[0023] Another solution to increase strength is to introduce glue between the nozzle and the liner, but this is a long operation that slows down the tank manufacturing process and is difficult to control.

[0024] Documents US2008251520, US2007164561, WO2018002788 and WO2013008719 disclose tanks comprising a plastic liner, a neck surrounding an axial orifice of the liner, a reinforcing envelope covering the liner, and a nozzle comprising a first annular projection and an outer axial end, the tank comprising a sealed contact surface between the nozzle and the reinforcing envelope which extends between the first annular projection and the axial end of the nozzle.

[0025] Also known from document EP0810081 is a tank comprising a plastic liner, a neck surrounding an axial orifice of the liner, a reinforcing envelope covering the liner, and a nozzle comprising a first annular projection and an outer axial end. The tank further comprises a seal disposed between the neck and a pressure element pressing the seal against the nozzle and against the liner.

[0026] The invention aims in particular to increase the strength of the connection between the end piece and the liner and to limit damage to the liner when the tank is under pressure. Optimally, this increase in the torque strength of the connection between the end piece and the liner is achieved without increasing the size of the tank and without slowing down the tank manufacturing process.

[0027] To this end, the invention relates to a tank intended to contain a pressurized gas comprising a plastic liner of generally cylindrical shape extending along a main axis, comprising a neck surrounding an axial orifice of the liner, a reinforcing envelope covering the liner, and an end piece extending along the main axis at least partially formed in the neck, the end piece comprising at least: an axial opening, a first annular projection extending radially towards the outside of the tank relative to the axial opening, a second annular projection extending radially towards the outside of the tank relative to the axial opening, the second annular projection being arranged axially towards the outside of the tank relative to the first annular projection, and an outer axial end extending at least partly outside the tank,characterized in that the liner extends from the first annular projection to the second annular projection, covering at least a portion of the first annular projection, and in that the reservoir further comprises a sealed contact surface between the end piece and the neck of the liner, which extends between the first annular projection and the second annular projection, as well as a contact surface between the end piece and the reinforcing casing, which extends axially between the second annular projection and the axial end of the end piece.,

[0028] An "annular projection" of the tip means a section of the tip extending radially from the tip and extending beyond the tip so as to have a free upper axial surface and a free lower axial surface.

[0029] By virtue of the fact that the liner extends from the first annular projection (or first fin) to the second annular projection (or second fin) by covering at least a portion of the first annular projection, the risks of degradation of the liner due to the forces exerted on the latter by the nozzle when the tank is under pressure are limited in an area close to the opening of the tank. A good seal is also ensured at the opening of the tank. In addition, by virtue of the fact that the tank comprises a sealed contact surface between the nozzle and the neck of the liner, which extends between the first annular projection and the second annular projection, the liner is sandwiched between, on the one hand, the nozzle and, on the other hand, the reinforcing envelope in a contact area which forms a baffle, which makes it possible to further limit, in an area close to the opening of the tank, the risks of degradation of the liner.Indeed, when the tank is under pressure, static and dynamic forces are exerted on the neck of the liner by the nozzle. An example of liner degradation due to static forces is the creep of the liner plastic material at the neck. An example of degradation due to dynamic forces is the fatigue of the liner plastic material at the neck.

[0030] In addition to the aforementioned risks of liner degradation, excessive pressure in the tank, for example during hydraulic cycling tests of the tank as prescribed in Regulation No. 134 of the United Nations Economic Commission for Europe (UNECE), can cause degradation or even breakage of the nozzle. The invention also makes it possible to limit these risks.

[0031] Furthermore, the fact that a direct contact surface is provided between the end piece and the reinforcement casing, which extends axially between the second annular projection and the axial end of the end piece, makes it possible to create an area, further away from the opening of the tank, in which, on the one hand, a good mechanical connection is created between the reinforcement casing and the end piece and, on the other hand, the liner is not sandwiched between the end piece and the reinforcement casing. The presence of such an area makes it possible to limit the risks of degradation of the liner by the end piece and the reinforcement casing. An example of degradation of the liner is the shearing of the liner by the end piece and the reinforcement casing. Another example of degradation of the liner is the creep of the plastic material of the liner.

[0032] Thus, the invention has the advantage of limiting the risks of degradation of the liner in the area of ​​the opening of the tank, while limiting the risks of degradation of the liner by the end piece and the reinforcement casing, in particular by shearing of the liner by the end piece and the reinforcement casing. Thus, by increasing the strength of the connection between the end piece and the liner, damage to the liner is prevented when the tank is under pressure, all without increasing the size of the tank and without slowing down the manufacturing process of the tank.

[0033] According to a preferred embodiment, the neck of the liner extends axially towards the outside of the tank relative to the axial orifice of the liner. This makes it possible to create a contact surface between the neck of the liner and the reinforcing casing, which extends between the first annular projection and the second annular projection. By this arrangement, the reinforcing casing ensures that the forces exerted on the neck of the liner by the nozzle when the tank is under pressure are absorbed by the reinforcing casing.

[0034] According to a preferred embodiment, the first annular projection is integral with the end piece. This makes it possible, on the one hand, to simplify the manufacture of the tank by limiting the number of additional parts and avoiding their attachment, and on the other hand, to provide better sealing between the end piece and the liner.

[0035] According to a preferred embodiment, the second annular projection is also integral with the end piece. This makes it possible, on the one hand, to simplify the manufacture of the tank by limiting the number of additional parts and avoiding their attachment, and on the other hand, to provide better sealing between the end piece and the liner.

[0036] According to a particular embodiment, the outer axial end of the end piece is not part of the second annular projection of the end piece and vice versa, in other words, they are not a zone or a direct extension of each other. In this case, the reinforcing casing completely covers the second annular projection, which makes it possible to increase the contact surface between the end piece and the reinforcing casing and to ensure good mechanical contact between these two elements.

[0037] In one variant, the outer axial end of the end piece is part of the second annular projection of the end piece. In this case, the reinforcing casing only partially covers the second annular projection.

[0038] Preferably, the axial end of the tip is an annular projection in the sense indicated above.

[0039] In order to further limit the risks of degradation of the liner and to further improve the sealing at the opening of the tank, according to a particular embodiment, the liner covers at least a portion of the second annular projection.

[0040] In order to further limit the risk of damage to the liner and to further improve the seal at the tank opening, the liner completely covers the first annular projection.

[0041] Preferably, the contact surface between the end piece and the reinforcing casing extends axially from the second annular projection to the axial end of the end piece. This makes it possible to increase the contact surface between the end piece and the reinforcing casing and to ensure good mechanical contact between these two elements.

[0042] According to a preferred embodiment, a largest diameter of the first annular projection is less than or equal to a largest diameter of the second annular projection, preferably strictly less than a largest diameter of the second annular projection. This makes it possible to minimize the mass of the tip by reducing its size.

[0043] According to a particular embodiment, a larger diameter of the first annular projection is strictly greater than a larger diameter of the second annular projection. This allows the nozzle to better resist breakage during hydraulic cycling tests of the tank according to Regulation No. 134 of the Economic Commission for Europe of the United Nations (UNECE).

[0044] According to a particular embodiment, the nozzle further comprises an inner axial end, opposite the outer axial end, which extends at least partly inside the tank. This makes it possible to maximize the useful volume of the tank in a restricted environment.

[0045] According to a particular embodiment, the end piece further comprises a third annular projection (or third fin) extending radially towards the outside of the tank relative to the axial opening, the third annular projection being arranged axially towards the outside of the tank relative to the second annular projection. This allows better absorption, by the reinforcing casing, of the forces exerted on the neck of the liner by the end piece when the tank is under pressure.

[0046] According to a preferred embodiment, the third annular projection is also integral with the end piece. This makes it possible, on the one hand, to simplify the manufacture of the tank by limiting the number of additional parts and avoiding their attachment, and on the other hand, to provide better sealing between the end piece and the liner.

[0047] According to a particular embodiment, a larger diameter of the third annular projection is smaller than that of the second annular projection. This makes it possible to minimize the mass of the tip.

[0048] According to a particular embodiment, the end piece further comprises an annular shoulder extending radially towards the outside of the reservoir relative to the axial opening, the annular shoulder being arranged axially towards the outside of the reservoir relative to the third annular projection.

[0049] Preferably, the end piece further comprises an external anchoring surface chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis, an adhesive surface and a combination of these surfaces, the external anchoring surface of the end piece being a sealed contact surface between the end piece and the neck of the liner and / or a contact surface between the end piece and the reinforcing casing. The presence of such an external anchoring surface makes it possible to reinforce the mechanical connection between the end piece and the neck of the liner and thus to increase the torque strength of this connection. This thus makes it possible to carry out a rapid filament winding process implementing significant acceleration and deceleration phases, and therefore to reduce the time and cost of manufacturing the tank.

[0050] A non-symmetrical surface of revolution around the principal axis is understood to mean a surface whose section in a plane perpendicular to the principal axis is not circular. This may include a flattened surface, a cross-sectional surface having a polygonal outline, for example, hexagonal, toothed, crenellated, grooved, elliptical, etc.

[0051] The invention also relates to a method for manufacturing a tank intended to contain a pressurized gas, characterized in that it comprises the following steps: providing a nozzle extending along a main axis, comprising an axial opening, a first annular projection extending radially towards the outside of the tank relative to the axial opening, a second annular projection extending radially towards the outside of the tank relative to the axial opening, the second annular projection being intended to be arranged axially towards the outside of the tank relative to the first annular projection, and an outer end intended to extend at least partly outside the tank; manufacturing a liner of generally cylindrical shape extending along an axis, the liner comprising a neck surrounding an axial orifice of the liner;fixing the end piece to the liner, such that the end piece is at least partially formed in the neck of the liner and the neck extends along the main axis, and such as to create a sealed contact surface between the end piece and the neck of the liner, which extends between the first annular projection and the second annular projection; fixing a reinforcing envelope to the liner and to the end piece, such that the reinforcing envelope covers the liner, and such as to create a contact surface between the end piece and the reinforcing envelope, which extends axially between the second annular projection and the axial end of the end piece.;

[0052] According to a particular embodiment, the liner is made of plastic and the end piece comprises an external anchoring surface chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis, an adhesive surface and a combination of these surfaces, and in which the step of fixing the end piece to the liner comprises a step of overmolding the neck of the liner onto the external anchoring surface of the end piece during the step of manufacturing the liner, the liner preferably being manufactured by extrusion blow molding. This makes it possible to simplify the manufacture of the tank. The presence of the adhesive surface makes it possible in particular to improve the sealing of the sealed contact surface between the end piece and the neck of the liner.

[0053] According to another particular embodiment, the liner is made of plastic material and the end piece comprises an external anchoring surface chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis, an adhesive surface and a combination of these surfaces, and in which the step of fixing the end piece to the liner comprises the following steps: overmolding, on the external anchoring surface of the end piece, an intermediate layer of plastic material chemically compatible with the plastic material of the liner, the intermediate layer preferably being manufactured by injection molding, overmolding the neck of the liner on the intermediate layer of plastic material during the step of manufacturing the liner, the liner preferably being manufactured by extrusion blow molding.

[0054] By "chemically compatible" is meant that the first and second polymer materials each comprise chemical species that can be welded together, without requiring the addition of additional material. In other words, chemically compatible polymer materials are capable of bonding intimately to each other by fusion, and in particular of producing molecular entanglement of polymer chains between them. Such molecular entanglement occurs by the application of heat to the location of contact.

[0055] Preferably, the rough surface of the tip is obtained by a step selected from etching the external anchoring surface of the tip, machining the external anchoring surface of the tip, molding the external anchoring surface of the tip, knurling the external anchoring surface of the tip and a combination of these steps, wherein the non-symmetrical surface of revolution around the main axis of the tip is obtained by machining and / or molding the external anchoring surface of the tip, and wherein the adhesive surface of the tip is obtained by depositing an adhesive on the external anchoring surface of the tip or by activating the external anchoring surface of the tip. The etching of the external anchoring surface of the tip can be done for example using a chemical etching agent or using a laser. The deposition of the adhesive surface of the tip can be done by spraying or by injection molding.Activation of the outer anchoring surface of the tip can be achieved by plasma, laser, or heating. Activation changes the surface tension of the outer anchoring surface of the tip to create free radicals on this surface, which create a covalent bond or Van der Waals bond with the plastic liner to promote mutual adhesion.

[0056] Preferably, the reinforcing envelope being made of a composite material comprising a resin and reinforcing fibers, the step of fixing the reinforcing envelope to the end piece and to the liner is a step of filament winding the reinforcing envelope onto the liner and the end piece during the step of manufacturing the reinforcing envelope. Brief description of the figures

[0057] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0058] is a local sectional view along a median plane of the connection zone of a tank intended to contain a pressurized gas according to a first embodiment of the invention;

[0059] is a sectional view along plane II-II of the;

[0060] is a perspective view of the reservoir nozzle of the;

[0061] is a bottom view of the tip of the;

[0062] is a local sectional view along a median plane of the connection zone of a tank intended to contain a pressurized gas according to a second embodiment of the invention;

[0063] is a local sectional view along a median plane of the connection zone of a tank intended to contain a pressurized gas according to a third embodiment of the invention;

[0064] is a local sectional view along a median plane of the connection zone of a tank intended to contain a pressurized gas according to a fourth embodiment of the invention;

[0065] is a sectional view along plan VIII-VIII of the;

[0066] is a perspective view of the reservoir nozzle of the;

[0067] is a bottom view of the tip of the;

[0068] is a local sectional view along a median plane of the connection zone of a tank intended to contain a pressurized gas according to a fifth embodiment of the invention;

[0069] is a sectional view along plan XII-XII of the;

[0070] is a perspective view of the reservoir nozzle of the;

[0071] is a bottom view of the tip of the;

[0072] is a local sectional view along a median plane of the connection zone of a tank intended to contain a pressurized gas according to a sixth embodiment of the invention;

[0073] is a sectional view according to plan XVI-XVI of the;

[0074] is a perspective view of the reservoir nozzle of the;

[0075] is a bottom view of the tip of the. Detailed description

[0076] A portion of a tank 10 intended to contain a pressurized gas according to a first embodiment of the invention is shown. The tank 10 comprises a liner 12 made of plastic material defining an internal volume V of the tank intended to receive the pressurized gas.

[0077] The liner 12 here has a central part of generally cylindrical or tubular shape, with reference to a main axis XX of the tank 10 and two end parts, one of which is shown in the. The end part of the liner 12 shown comprises a neck 14 surrounding an axial orifice 16 of the liner 12 putting the internal volume V of the tank into communication with the external environment, the neck 14 here extending towards the outside of the internal volume V. The liner 12 is preferably manufactured by injection, rotational molding or extrusion-blow molding of a thermoplastic or thermoset polymer material, for example polyamide or polyethylene, and the thickness of the liner 12 is for example less than or equal to 5 mm.

[0078] The tank 10 further comprises a reinforcing envelope 18 covering the liner 12, preferably made of composite material, which will constitute the body of the tank 10, that is to say the resistant structure of the tank 10.

[0079] The reinforcing envelope 18 preferably comprises a reinforcement consisting of fibers, for example continuous fibers, of glass, carbon, basalt, or others such as silica fibers or even plant fibers, and a resin which is either deposited at the same time as the fiber (for example by a filament winding process) or after the envelope has been produced to constitute a dry “preform”. This dry preform is then consolidated in order to give it the necessary rigidity. This consolidation is carried out using a resin injection or by infiltration of this resin through said preform (infusion process), or by vacuum impregnation of resin.

[0080] Advantageously, the reinforcing jacket 18 is coated with one or more layers of a fire-retardant material, preferably an intumescent fire-retardant material such as, for example, a silicate or phosphate-based coating. Silicate and phosphate are intumescent agents which, after exposure to fire, expand and create an insulating barrier. This makes it possible to improve the heat and fire resistance of the tank 10.

[0081] The tank 10 also comprises a nozzle 20 at least partially formed in the neck 14 of the liner 12. The nozzle 20 has a general shape with symmetry of revolution relative to the main axis XX. The nozzle 20 comprises a central part extending partially inside the neck 14 of the liner 12 and a peripheral part extending partially around the neck 14 of the liner 12 so that the neck 14 of the liner 12 is protected from the external environment by the nozzle 20. The nozzle 20 is a metal part, for example aluminum. The nozzle 20 is in particular configured to receive a solenoid valve (not shown in the figures) allowing, alternately, the tank 10 to be filled and emptied of its gas.

[0082] In all the embodiments shown in the figures, the reservoir 10 further comprises a sealed contact surface SG between the end piece 20 and the neck 14 of the liner.

[0083] The end piece 20 extends along the main axis XX and is at least partially formed in the neck 14. It comprises an axial opening 22 which extends along the main axis XX and is for example of substantially circular section.

[0084] As can be seen in particular in Figures 1 and 3, the end piece 20 further comprises an outer axial end 24 extending at least partly outside the tank 10. The adjective “outside” is understood here in relation to the volume V of the tank 10. The outer axial end 24 is therefore located outside the neck 14 of the liner and is not covered by the reinforcing envelope 18. The outer axial end 24 comprises an annular shoulder 26 extending radially towards the outside of the tank relative to the axial opening 22.

[0085] The end piece 20 further comprises an inner axial end 28, opposite the outer axial end 24, which extends at least partly inside the tank 10. The adjective “inner” is understood here in relation to the volume V of the tank 10. The inner axial end 28 is therefore outside the neck 14 of the liner and is not covered by the reinforcing envelope 18. It is inside the volume V of the tank 10.

[0086] The end piece 20 further comprises a first annular projection 31, or first fin 31, extending radially towards the outside of the reservoir 10 relative to the axial opening 22. The first annular projection 31 is here integral with the end piece 20. The term "annular projection" of the end piece 20 means a section of the end piece 20 extending radially from the end piece 20, and extending beyond the end piece 20 so as to comprise a free upper axial surface and a free lower axial surface.

[0087] In the embodiments shown in the figures, the outer axial end 24 is in particular a projection within the meaning of this definition. However, as will be seen later, this is only an example of an embodiment.

[0088] The first annular projection 31 preferably has radial symmetry around the main axis XX. Its radial contour is preferably of continuous curvature, that is to say does not have a sharp edge.

[0089] Preferably, the tip 20 further comprises an external anchoring surface SA chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis XX, an adhesive surface and a combination of these surfaces.

[0090] A non-symmetrical surface of revolution around the main axis XX is understood to mean a surface whose section in a plane perpendicular to the main axis XX is not circular. This may include a flattened surface, a cross-sectional surface having a polygonal outline, for example, hexagonal, toothed, crenellated, grooved, elliptical, etc.

[0091] The presence of such an external anchoring surface SA makes it possible to reinforce the mechanical connection between the end piece 20 and the neck 14 of the liner 12 and thus to increase the torque resistance of this connection.

[0092] In the first three embodiments shown in Figures 1 to 6, the first annular projection 31 carries such an external anchoring surface SA which is a non-symmetrical surface of revolution around the main axis XX.

[0093] Indeed, in these first three embodiments, the external anchoring surface SA locally has a cross-section, along a plane perpendicular to the axis XX, in this case in the section plane II-II, in the form of a toothed wheel, as can be seen in Figures 2 to 4 in particular, that is to say that it comprises a plurality of teeth 29 projecting from the first annular projection 31 extending radially towards the outside of the reservoir 10. Preferably the teeth 29 are distributed symmetrically around the axis XX. The number of teeth 29 of the wheel is here twelve, but this number can naturally vary. The shape of the teeth 29 is also substantially rectangular in this plane II-II, but can also vary.

[0094] The external anchoring surface SA is therefore in these first three embodiments formed from a succession of hollows (the spaces between the teeth 29) and protuberances (the teeth 29), which makes it possible to reinforce the mechanical connection between the end piece 20 and the neck 14 of the liner 12 and thus to increase the torque resistance of this connection.

[0095] The external anchoring surface SA here forms a portion of the sealed contact surface SG between the neck 14 and the end piece 20, but it could form the entire sealed contact surface SG. The proportion between the external anchoring surface SA and the sealed contact surface SG between the end piece 20 and the neck 14 can naturally vary according to requirements.

[0096] The end piece 20 also comprises a second annular projection 32, or second fin 32, extending radially towards the outside of the reservoir 10 relative to the axial opening 22. The second annular projection 32 is arranged axially towards the outside of the reservoir 10 relative to the first annular projection 31, that is to say towards the top of the figures relative to the first annular projection 31. The second annular projection 32 is here integral with the end piece 20.

[0097] In the embodiments shown in the figures, the outer axial 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 one another. In this case, the reinforcing casing 18 completely covers the second annular projection 32, which makes it possible to increase the contact surface between the end piece 20 and the reinforcing casing 18 and to ensure good mechanical contact between these two elements.

[0098] However, in a variant not shown, the outer axial end 24 of the end piece forms part of the second annular projection 32 of the end piece. In this case, the reinforcing casing 18 only partially covers the second annular projection 32.

[0099] The second annular projection 32 preferably has radial symmetry around the main axis XX. Its radial contour is preferably of continuous curvature, i.e. does not have a sharp edge. In all the embodiments shown in the figures, its cross-section along a plane perpendicular to the axis XX is substantially circular. Naturally, the shape of the second annular projection 32 may vary.

[0100] In the first embodiment of the invention shown in Figures 1 to 4, a largest diameter D1 of the first annular projection 31 is strictly greater than a largest diameter D2 of the second annular projection 32.

[0101] However, according to a second embodiment of the invention illustrated in , a larger diameter D1 of the first annular projection 31 is substantially equal to a larger diameter D2 of the second annular projection 32. The reservoir 10 is otherwise identical to that of the first embodiment.

[0102] According to a third embodiment of the invention illustrated in, a largest diameter D1 of the first annular projection 31 is less than or equal to a largest diameter D2 of the second annular projection 32, preferably strictly less than a largest diameter of the second annular projection 32. The reservoir 10 is otherwise identical to that of the first embodiment.

[0103] In all the embodiments shown in the figures, the sealed contact surface SG between the end piece 20 and the neck 14 of the liner 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.

[0104] According to a particular embodiment, the end piece further comprises a third annular projection (or third fin) 33 extending radially towards the outside of the reservoir 10 relative to the axial opening 22. The third annular projection 33 is arranged axially towards the outside of the reservoir 10 relative to the second annular projection 32, that is to say towards the top of the figures relative to the second annular projection 32. The third annular projection 33 is here integral with the end piece 20.

[0105] The third annular projection 33 preferably has radial symmetry around the main axis XX. Its radial contour is preferably of continuous curvature, i.e. does not have a sharp edge. In all the embodiments shown in the figures, its cross-section along a plane perpendicular to the axis XX is substantially circular. Naturally, the shape of the third annular projection 33 can vary.

[0106] In all the embodiments illustrated in the figures, a larger diameter D3 of the third annular projection 33 is smaller than that of the second annular projection 32, as can be seen in figures 1, 5, 7, 11 and 15. Nevertheless, it is possible to vary this diameter as required.

[0107] In all the embodiments shown in the figures, the reservoir 10 also comprises a contact surface SE between the end piece 20 and the reinforcing casing 18, which extends axially between the second annular projection 32 and the outer axial end 24 of the end piece 20, as can be seen in figures 1, 5, 7, 11 and 15.

[0108] In all the embodiments illustrated in the figures, the neck 14 of the liner 12 extends axially towards the outside of the tank 10 relative to the axial orifice 16 of the liner 12. This makes it possible to create a contact surface between the neck 14 of the liner 12 and the reinforcing envelope 18, which extends between the first annular projection 31 and the second annular projection 32.

[0109] In all the embodiments shown in the figures, the liner 12 extends from the first annular projection 31 to the second annular projection 32, covering at least a portion of the first annular projection 31, as can be seen in figures 1, 5, 7, 11 and 15. This further limits, in an area close to the opening of the reservoir 10, the risks of degradation of the liner 12 due to the forces exerted on the latter by the end piece 20 when the reservoir 10 is under pressure. Good sealing is also ensured at the opening of the reservoir 10.

[0110] In order to further limit the risks of degradation of the liner 12 and to further improve the sealing at the opening of the tank 10, in all the embodiments shown in the figures, 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.

[0111] In order to further limit the risks of degradation of the liner 12 and to further improve the sealing at the opening of the tank 10, in all the embodiments shown in the figures, the liner 12 completely covers the first annular projection, as can be seen in figures 1, 5, 7, 11 and 15.

[0112] Preferably, the contact surface SE between the end piece 20 and the reinforcing casing 18 extends axially from the second annular projection to the axial end of the end piece 20. This makes it possible to increase the contact surface SE between the end piece 20 and the reinforcing casing 18 and to ensure good mechanical contact between these two elements.

[0113] In a variant not shown in the figures, the external anchoring surface SA forms a portion of the contact surface SE between the end piece 20 and the reinforcement casing 18, or the entire contact surface SE between the end piece 20 and the reinforcement casing 18. In yet another variant not shown in the figures, the end piece 20 comprises two external anchoring surfaces SA which respectively form a portion, or the entirety, of the sealed contact surface SG between the neck 14 of the liner 12 and the end piece 20 and of the contact surface SE between the end piece 20 and the reinforcement casing 18.

[0114] In a fourth embodiment illustrated 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 largest diameter, i.e. plane VIII-VIII.

[0115] The first annular projection 31 thus has, as can be seen in figures 8 and 10, six substantially planar faces 34 distributed symmetrically around the main axis XX, the meeting of which forms an external anchoring surface SA which is not symmetrical in revolution around the main axis XX.

[0116] In a fifth embodiment illustrated in Figures 11 to 14, the first annular projection 31 comprises, on its periphery, a plurality of lateral notches 36. The lateral notches 36 here have a T-shaped section in a plane perpendicular to the main axis XX, in this case the plane of its largest diameter, here the plane XII-XII as can be seen in the. When observing the end piece 20 from the side, as in the, the lateral notches 36 have the shape of a capital I. The lateral notches 36 are preferably distributed symmetrically around the axis XX. They are for example nine in number but this number can naturally vary.

[0117] The first annular projection 31 thus has an external anchoring surface SA which is not symmetrical in revolution around the main axis XX.

[0118] In a sixth embodiment illustrated in Figures 11 to 14, the first annular projection 31 has an oval-shaped cross-section along a plane perpendicular to the main axis XX, in this case the plane of its largest diameter, i.e. plane XVI-XVI.

[0119] The first annular projection 31 thus has, as can be seen in figures 8 and 10, oblong faces 38 whose meeting forms an external anchoring surface SA which is not symmetrical in revolution around the main axis XX.

[0120] We will now describe an example of a method for manufacturing a tank 10.

[0121] In a first step, a tip such as the tip 20 is provided, i.e. extending along a main axis XX, comprising an axial opening 22, a first annular projection 31 extending radially towards the outside of the reservoir 10 relative to the axial opening 22, a second annular projection 32 extending radially towards the outside of the reservoir 10 relative to the axial opening 22, the second annular projection 32 being intended to be arranged axially towards the outside of the reservoir 10 relative to the first annular projection 31, and an outer axial end 24 intended to extend at least partly outside of the reservoir 10.

[0122] In the case where the tip 20 comprises an external anchoring surface SA comprising a rough surface, the latter is obtained by a step chosen from etching the external anchoring surface SA of the tip, machining the external anchoring surface of the tip, molding the external anchoring surface SA of the tip, knurling the external anchoring surface SA of the tip and a combination of these steps, in which the non-symmetrical surface of revolution around the main axis of the tip XX is obtained by machining and / or molding the external anchoring surface SA of the tip, and in which the adhesive surface of the tip is obtained by depositing an adhesive on the external anchoring surface SA of the tip or by activating the external anchoring surface of the tip SA. The etching of the external anchoring surface SA of the tip can be done for example using a chemical etching agent or using a laser.The adhesive surface of the tip can be deposited by spraying or injection molding. The activation of the external anchoring surface SA of the tip can be carried out by plasma, laser or heating.

[0123] A liner 12 of generally cylindrical shape extending along an axis XX is then manufactured. This liner 12 comprises a neck 14 surrounding an axial orifice 16 of the liner 12. The liner 12 is for example made of plastic material and preferably manufactured by extrusion blow molding.

[0124] The end piece 20 is then fixed to the liner 12, so that the end piece 20 is at least partially formed in the neck 14 of the liner 12 and the neck 14 extends along the main axis XX, and so as to create a sealed contact surface SG between the end piece 20 and the neck 14 of the liner 12, which 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 in particular comprise a step of overmolding the neck 14 of the liner 12 on the external anchoring surface SA of the end piece during the step of manufacturing the liner 12.

[0125] In a variant, the end piece 20 is fixed to the liner 12 by overmolding, on the external anchoring surface SA of the end piece, an intermediate layer of plastic material chemically compatible with the plastic material of the liner 12, the intermediate layer preferably being manufactured by injection molding, and by overmolding the neck 14 of the liner 12 on the intermediate layer of plastic material during the step of manufacturing the liner 12.

[0126] A reinforcing envelope 18 is then fixed to the liner 12 and to the end piece 20, so that the reinforcing envelope 18 covers the liner 12, and so as to create a contact surface SE between the end piece 20 and the reinforcing envelope 18, which extends axially between the second annular projection 32 and the outer axial end 24 of the end piece 20. Preferably, the reinforcing envelope 18 is made of a composite material comprising a resin and reinforcing fibers.

[0127] Also preferably, the fixing of the reinforcing envelope 18 to the end piece 20 and to the liner 12 is a step of filament winding of the reinforcing envelope 18 onto the liner and the end piece 20 during the step of manufacturing the reinforcing envelope 18.

[0128] The invention is not limited to the embodiments presented and other embodiments will become clear to those skilled in the art. In particular, it may be envisaged to vary the largest diameters of the first, second and third annular projections in the fourth, fifth and sixth embodiments in the same way as in the first, second and third embodiments. List of references

[0129] 10: Tank12: Liner14: Neck16: Axial orifice of the liner18: Reinforcing casing20: End cap22: Axial opening of the end cap24: Outer axial end of the end cap26: Annular shoulder of the end cap28: Inner axial end of the end cap29: Teeth of the first annular projection31: First annular projection of the end cap32: Second annular projection of the end cap33: Third annular projection of the end cap34: Faces of the hexagon36: Lateral notches38: Oblong facesD1: Largest diameter of the first annular projectionD2: Largest diameter of the second annular projectionD3: Largest diameter of the third annular projectionV: Internal volume of the tankSA: External anchoring surface of the end capSE: Contact surface between the end cap and the reinforcing casingSG : Sealed contact surface between the neck and the nozzleX-X: Main axis of the tank

Claims

Tank (10) intended to contain a pressurized gas comprising a liner (12) made of plastic material of generally cylindrical shape extending along a main axis (XX), comprising a neck (14) surrounding an axial orifice (16) of the liner (12), a reinforcing envelope (18) covering the liner (12), and a nozzle (20) extending along the main axis (XX) at least partially formed in the neck (14), the nozzle (20) comprising at least: - an axial opening (22), - a first annular projection (31) extending radially towards the outside of the tank (10) relative to the axial opening (22), - a second annular projection (32) extending radially towards the outside of the tank (10) relative to the axial opening (22), the second annular projection (32) being arranged axially towards the outside of the tank (10) relative to the first annular projection (31), and- an outer axial end (24) extending at least partly outside the reservoir (10),characterized in that the liner (12) extends from the first annular projection (31) to the second annular projection (32) while covering at least a portion of the first annular projection (31) and, in that the reservoir (10) further comprises a sealed contact surface (SG) between the end piece (20) and the neck (14) of the liner (12), which extends between the first annular projection (31) and the second annular projection (32), as well as a contact surface (SE) between the end piece (20) and the reinforcing casing (18), which extends axially between the second annular projection (32) and the outer axial end (24) of the end piece (20)., Tank (10) according to the preceding claim, in which the neck (14) of the liner (12) extends axially towards the outside of the tank (10) relative to the axial orifice (16) of the liner (12). A tank (10) according to any preceding claim, wherein the liner (12) covers at least a portion of the second annular projection (32). A tank (10) according to any preceding claim, wherein the liner (12) completely covers the first annular projection (31). Tank (10) according to any one of the preceding claims, in which the contact surface (SE) between the end piece (20) and the reinforcing casing (18) extends axially from the second annular projection (32) to the outer axial end (24) of the end piece (20). Tank (10) according to any one of the preceding claims, wherein a largest diameter of the first annular projection (31) is less than or equal to a largest diameter of the second annular projection (32), preferably strictly less than a largest diameter of the second annular projection (32). Tank (10) according to any one of claims 1 to 5, wherein a largest diameter of the first annular projection (31) is strictly greater than a largest diameter of the second annular projection (32). A reservoir (10) according to any preceding claim, wherein the end piece (20) further comprises a third annular projection (33) extending radially outwardly of the reservoir (10) relative to the axial opening (22), the third annular projection (33) being disposed axially outwardly of the reservoir (10) relative to the second annular projection (32). Tank (10) according to any one of the preceding claims, in which the end piece (20) further comprises an external anchoring surface (SA) chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis (XX), an adhesive surface and a combination of these surfaces, the external anchoring surface (SA) of the end piece being a sealed contact surface (SG) between the end piece (20) and the neck (14) of the liner (12) and / or a contact surface (SE) between the end piece (20) and the reinforcing envelope (18). A method of manufacturing a tank (10) intended to contain a pressurized gas, characterized in that it comprises the following steps:- providing a nozzle (20) extending along a main axis (XX), comprising an axial opening (22), a first annular projection (31) extending radially towards the outside of the tank (10) relative to the axial opening (22), a second annular projection (32) extending radially towards the outside of the tank (10) relative to the axial opening (22), the second annular projection (32) being intended to be arranged axially towards the outside of the tank (10) relative to the first annular projection (31), and an outer axial end (24) intended to extend at least partly outside the tank (10);- manufacturing a liner (12) of generally cylindrical shape extending along an axis (XX), the liner comprising a neck (14) surrounding an axial orifice (16) of the liner (12);- fixing the end piece (20) to the liner (12), such that the end piece (20) is at least partially formed in the neck (14) of the liner (12) and that the neck (14) extends along the main axis (XX), and so as to create a sealed contact surface (SG) between the end piece (20) and the neck (14) of the liner (12), which extends between the first annular projection (31) and the second annular projection (32);- fixing a reinforcing casing (18) to the liner (12) and to the end piece (20), such that the reinforcing casing (18) covers the liner (12), and so as to create a contact surface (SE) between the end piece (20) and the reinforcing casing (18) which extends axially between the second annular projection (32) and the end external axial (24) of the tip (20).; Method according to claim 10, in which the liner (12) is made of plastic and the end piece (20) comprises an external anchoring surface (SA) chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis (XX), an adhesive surface and a combination of these surfaces, and in which the step of fixing the end piece (20) to the liner (12) comprises a step of overmolding the neck (14) of the liner (12) on the external anchoring surface (SA) of the end piece during the step of manufacturing the liner (12), the liner (12) preferably being manufactured by extrusion blow molding. Method according to claim 10, wherein the liner (12) is made of plastic material and the end piece (20) comprises an external anchoring surface (SA) chosen from the group comprising a rough surface, a non-symmetrical surface of revolution around the main axis (XX), an adhesive surface and a combination of these surfaces, and wherein the step of fixing the end piece (20) to the liner (12) comprises the following steps: - overmolding, on the external anchoring surface (SA) of the end piece, an intermediate layer of plastic material chemically compatible with the plastic material of the liner (12), the intermediate layer preferably being manufactured by injection molding, - overmolding the neck (14) of the liner (12) on the intermediate layer of plastic material during the step of manufacturing the liner (12), the liner (12) preferably being manufactured by extrusion blow molding. Method according to any one of claims 11 to 12, wherein the rough surface of the tip (20) is obtained by a step chosen from etching the external anchoring surface of the tip, machining the external anchoring surface (SA) of the tip, molding the external anchoring surface (SA) of the tip, knurling the external anchoring surface (SA) of the tip and a combination of these steps, wherein the non-symmetrical surface of revolution around the main axis (XX) of the tip is obtained by machining and / or molding the external anchoring surface of the tip, and wherein the adhesive surface of the tip is obtained by depositing an adhesive on the external anchoring surface (SA) of the tip or by activating the external anchoring surface (SA) of the tip. Method according to any one of claims 10 to 13, in which the reinforcing envelope (18) is made of a composite material comprising a resin and reinforcing fibers, the step of fixing the reinforcing envelope (18) to the end piece (20) and to the liner (12) is a step of filament winding the reinforcing envelope (18) on the liner (12) and the end piece (20) during the step of manufacturing the reinforcing envelope (18).

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