Hydrogen tank

Abstract

The invention relates to a hydrogen tank (1) configured for storing hydrogen, comprising: a plurality of tubes (10) for containing hydrogen, arranged parallel to one another in a longitudinal direction, each having a liner (12) surrounded by a composite shell (13); coupling members (20) arranged at least one end (11) of each tube (10); and a longitudinal composite shell (40) arranged around the plurality of tubes (10) and around the coupling members (20) to bear longitudinal loads applied on the coupling members (20); wherein each coupling member (20) is configured to fluidly couple two adjacent tubes (10), the coupling members (20) being arranged to serially connect all the tubes (10).

Description

[0001] HYDROGEN TANK

[0002] Technical field

[0003] The present invention generally relates to a tank for pressurized fuel, in particular configured for storing hydrogen.

[0004] Background Art

[0005] A hydrogen tank can usually be used for storing hydrogen in a fluid state. This typically necessitates the hydrogen to comprise a relatively high pressure, i.e. at least an order of magnitude higher than atmospheric pressure. It is well known within the art to make hydrogen tanks with composite shells to bear loads that originate from the pressure of the stored hydrogen as a lightweight construction.

[0006] EP 3 346 179 A1 discloses a hydrogen tank, comprising a plurality of body parts arranged side by side, having a cylindrical shape and being covered with a first fiber reinforced resin member in a circumferential direction. A cap with a communication channel in its inside closes openings of the body parts. The first fiber reinforced resin member and the cap are covered as a unit along an axial direction of the body parts with a second fiber reinforced resin member having a fiber direction corresponding to the axial direction.

[0007] US 2022 / 0260207 A1 discloses a device for storing gas and comprising parallel tubes. The ends of the tubes are hermetically connected to collectors of a manifold type. The tubes and the collectors are wrapped inside a belt. The belt is made by winding a reinforcing tape around the assembly. The tape has a straight shape parallel to the axial direction of the tubes. The collector is made of composites of reinforcement fiber and thermoplastic polymeric matrix as the same type as the tubes.

[0008] WO 2021 / 110707 A1 discloses an assembly for storing pressurized fluid, comprising a plurality of parallelly arranged, cylindrical reservoirs, each reservoir with a first end piece provided with a fluid passage duct, and a use collector duct with orifices connected to the reservoirs. The reservoirs comprise a reinforcing structure, e.g. produced by winding strips of composite material based on polymer filled with glass or carbon fibers. The manufacture of the known hydrogen tanks is cumbersome. Additionally, the known hydrogen tanks comprise a high weight and size.

[0009] Technical problem

[0010] It is an object of the present invention to provide a gas / hydrogen tank whose size and weight are optimized. Further, it is an object to provide a gas / hydrogen tank that can be produced easier. Further, it is an object to provide a solution that reduces or avoids drawbacks of prior art.

[0011] This object is achieved by a tank as claimed in claim 1 .

[0012] General Description of the Invention

[0013] To achieve these objects, the present invention proposes a tank configured for storing pressurized fuel, in particular gaseous fuel such as hydrogen, comprising: a plurality of tubes for containing the pressurized fuel, arranged parallel to one another in a longitudinal direction, each having a liner surrounded by a composite shell; coupling members arranged at at least one end of each tube; and a longitudinal composite shell arranged around the plurality of tubes and around the coupling members to bear longitudinal loads applied on the coupling members (due to internal pressure). For optimizing size, weight and manufacture, each coupling member is configured to fluidly couple two adjacent tubes, the coupling members being arranged to serially connect all of the tubes.

[0014] In other words, particularly, a storage device for pressurized fuel is proposed that has fiber-reinforced pipes I tubes arranged side by side, that has connectors arranged at one end of the tubes, and that has a fiber-reinforced housing around tubes and connectors and is configured for bearing loads along the tubes. Each connector connects two tubes arranged next to each other for providing a connection of the tubes in series.

[0015] The present tank has been designed for storing pressurized fuel such as hydrogen, i.e. in gas state. However, it can likewise be used for storing other gaseous fuel for engines, e.g. CNG, biogas, methanol, syngas etc.; as well as fuel that is stored under pressure in liquid form, and discharged in gaseous state.

[0016] The present invention offers a cost-controlled manufacturing process by a design involving the longitudinal composite shell to bear most of the longitudinal loads, and involving tubes with a liner, especially a metallic one, particularly an aluminum liner, and a composite shell that may bear hoop stress. The tubes and the coupling members and the like may be pushed (laterally) into the longitudinal composite shell, which may be manufactured independently; this makes manufacturing easier. The design also offers enhanced modularity, making the sizing of the tank more flexible. It further reduces the diversity of parts.

[0017] The present tank forms an assembly that is particularly able to store pressurized hydrogen in a fluid state, especially a liquid and / or gaseous state, at pressures of several hundred bars, e.g. up to 350 or 700 bars. The hydrogen tank can for example be used in a mobile application, for example a vehicle that uses hydrogen as a fuel, namely a vehicle powered by a H2 fuel cell or H2-ICE.

[0018] In embodiments, the tubes extend with a substantially constant cross-sectional shape along the longitudinal direction. The tubes may have a circular cross-section, or another appropriate shape.

[0019] The coupling members may be understood as plugs connecting consecutive tubes. A coupling member is typically configured for guiding the hydrogen into and out of the tubes and particularly from one tube to another, especially adjacent, tube. Typically, the coupling member connects exactly two adjacent tubes. By way of connecting a plurality of tubes, say three or more, a meandering flow path of hydrogen in the hydrogen tank may be achieved. The number of tubes depends on the tube dimensions and desired total storage capacity, for example the number of tubes may vary between 3 and 10.

[0020] In embodiments, all of the coupling members are of same design, i.e. they have substantially the same shape, material and / or size. Thus, the coupling members may be substantially identical. Advantageously, same coupling members are used for all coupling members that are comprised by the hydrogen tank and / or that couple two adjacent tubes.

[0021] In embodiments, the coupling members comprises a base portion with two protrusions, preferably cylindrical protrusions in particular of circular cross-section. The cylindrical protrusions may be monolithically formed on the base portion. The respective cylindrical protrusion may be engaged in a respective end of a tube and / or may have a concave surface facing the tube interior, for improving pressure load distribution. A channel is normally arranged in each coupling member. The channel preferably extends from one cylindrical protrusion, preferably through the base portion, to the other cylindrical protrusion to fluidly couple two adjacent tubes. The channel may have a channel end substantially atop and / or in the middle of the respective cylindrical protrusion, for example opening in the (concave) surface facing the tube interior. The channel hence allows flow of gas / hydrogen from one tube to the other tube connected to said channel especially via said cylindrical protrusions. This configuration improves modularity and the manufacture of the hydrogen tank. A form fit with the tubes may enhance safety and stability of the assembly.

[0022] It is preferred that each one of the coupling members comprises or is made of metal, especially an aluminum alloy, in particular aluminum or aluminum alloy. The coupling member may be manufactured in any appropriate way, e.g. by metal casting or additive manufacturing, in combination with machining. Preferably the coupling is made in one piece (monolithic component), which provides enhanced safety and stability. The channel may be provided as a bore or as an arrangement of bores in the coupling member. For example, an angled bore may extend from a respective cylindrical protrusion to form the channel with the other bore.

[0023] Advantageously, gaskets are provided for sealing between each cylindrical protrusion of the coupling member and the respective tube. Any appropriate gasket may be employed, which is adapted for working pressures of several hundred bars. The gasket may generally be of annular / ring shape. The gasket may comprise one, two or more gasket portions. It may e.g. comprise a resilient ring (elastomer or rubber) able to expand under increasing pressure, in combination with a rigid support ring (e.g. PTFE). The gasket is arranged at the periphery of each cylindrical protrusions, e.g. in a circumferential recess, and engages with an inner surface of the respective tube. The recess may be formed by an annular groove or preferably by a peripheral shoulder, facilitating the gasket installation. The use of such gasket, which is a non-fixed mechanical element, is preferred to welding I brazing I gluing at the tube I coupling member interface, which imposes a rigid connection that transfers mechanical stress. In other words, the gasket permits some flexibility at the tube - coupling member interface, making assembly easier and avoiding mechanical stress due to tube radial deformation under internal pressure. Preferably, the cylindrical protrusions have a (outer) diameter substantially equal to an inner diameter of each of the plurality of tubes. In other words, a radial gap between the inside of the tube and the cylindrical protrusion is as little as possible, for example 1 mm or less. One could also say that the cylindrical protrusions have an outer diameter matching the inner diameter of each of the plurality of tubes.

[0024] Typically, the tubes have a substantially cylindrical form in cross-section, i.e. the liner and the composite shell are substantially cylindrical, with constant diameter. The composite shell is typically produced / formed on the liner. Preferably, the composite shell surrounding the liner comprises circumferentially wound resin impregnated filaments. Circumferentially wound means that the winding angle is of about 80 to 90°, preferably 85 to 90°, with respect to the longitudinal axis. Preferably, said filaments are wound substantially unidirectionally, i.e. in the circumferential direction, especially wherein 90 %, 95 %, or more (in number, volume or weight) of the filaments are wound unidirectionally. Typically, the composite shell forms no gap in a radial direction with the liner. Thus, hoop stress is compensated by said filaments.

[0025] In a radial direction, the liner is preferably thinner than the composite shell surrounding the liner. For example, the composite shell may be at least 10 %, 25 %, 50 %, 100 %, 200 %, 300 %, or more thicker than the liner.

[0026] It is preferred that all of the tubes comprise substantially the same shape, material and / or size. Thus, the tubes may be substantially identical. Preferably, same tubes are used for all tubes that are comprised by the hydrogen tank and / or that are arranged in parallel for containing hydrogen.

[0027] The longitudinal composite shell may be configured as a housing to surround components of the hydrogen tank and to bear longitudinal loads I axial loads. Preferably, the longitudinal composite shell comprises wound resin impregnated filaments arranged substantially along the longitudinal direction. Preferably, said filaments are wound substantially unidirectionally in the longitudinal direction, especially wherein 90 %, 95 %, or more (in number, volume or weight) of the filaments are wound unidirectionally. The filaments are wound longitudinally, i.e. they form a angle between 0 and 10°, preferably between 0 and 5° with the longitudinal axis. Said filaments preferably make a turn by substantially 180° at the respective ends of the tubes with the coupling members. The longitudinal composite shell may have two or more substantially parallel sections to be arranged along the longitudinal direction and / or two substantially curved ends connecting the two substantially parallel sections, particularly which ends are configured to be arranged at the ends of the tubes, especially configured for bearing mechanical loads along the longitudinal direction. The curved ends may comprise a concave inside surface. Particularly, in a direction oblique to the longitudinal direction and / or in parallel to the two or more substantially parallel sections, the longitudinal composite shell may be open on at least one side, especially at both sides.

[0028] Preferably, the tubes comprise an / the inner diameter of at least 100 mm, 150 mm or 200 mm. The cylindrical protrusions of the coupling members may have a corresponding diameter, especially including an undersize or an oversize by up to 5 %, 2 % or 1 %, especially including substantially the same diameter.

[0029] It is understood that the composite shells surrounding the tubes and the longitudinal composite shell are preferably manufactured by means of filament winding technology, although other techniques may be used. That is, by winding endless filaments (strands / roving of filaments / fibers) of glass, carbon or other material to provide mechanical strength, which are impregnated with a resin that forms a matrix material binding the filaments together. The filament strands can be wet impregnated (during the course of the winding process) or pre-impregnated with semi-polymerized resin.

[0030] Any appropriate types of filaments / fibers and resin may be used. Particularly, the resin for the tube composite shell may be a thermoset resin, such as e.g. epoxy resins.

[0031] Advantageously, the resin for the longitudinal and radial composite may be a thermoplastic resin, such as e.g. polyamide or polyethylene, which facilitates recycling.

[0032] Preferably, the inventive tank comprises at least one end member closing an end of a respective tube and configured for providing a port to the stored hydrogen. In this configuration, it is preferred that the longitudinal composite shell additionally surrounds the at least one end member. Thus, the longitudinal composite shell houses at least: the tubes, the coupling elements, and the end member(s) and can thereby bear longitudinal loads going through all of these components.

[0033] Preferably, the inventive tank comprises a support member, especially a first support member and a second support member, being in contact to, especially coupled to, the coupling member(s) and / or the at least one end member. The support member is particularly coupled to the coupling member or coupling members by means of a positive fit joint, especially a dovetail joint. The support member may transfer longitudinal loads on the coupling members to the longitudinal composite shell. The support member may be in the form of a rail and / or may be elongated, especially in a direction oblique or perpendicular to the longitudinal direction. The support member realizes that an intermediate component is provided for mechanical load transfer which intermediate component not necessarily is in direct contact to the stored hydrogen. Thereby, a limitation in choice of material is reduced and mechanical design can be optimized. Furthermore, the single coupling members can be provided to form a structural unit which further enhances stability and safety of the hydrogen tank.

[0034] The inventive tank may comprise the first support member and the second support member. Said support members may be arranged on opposing ends of the plurality of tubes. Thus, said support members may be arranged at two opposing positions along the longitudinal direction. The second support member may have a similar or equal design (i.e. dimensions and / or material) as the first support member. This further enhances the above-described design.

[0035] Preferably, the support member(s) has / have a round shape facing a corresponding inside surface of the longitudinal composite shell. For example, the support member may be coupled on one side to the coupling member(s) I end member(s) and on an opposing side in direct or indirect contact with the longitudinal composite shell (viewed in the longitudinal direction). The round shape may be a convex shape in contact with a concave shape of the inside surface. This especially provides a contact in terms of area for smooth load distribution. This further enhances the above-described design.

[0036] Preferably, the support member(s) is / are hollow. The support member(s) may be an extruded part, e.g. made by extrusion, especially aluminum extrusion. The support member(s) may be in the form of an aluminum profile. One or more cavities inside the support member may be provided. The cavity preferably comprise a substantially rounded or roundish cross-sectional shape to decrease kerf stresses but providing weight reduction. Ends of the support member may be covered by means of a cover, especially to close the inside and / or the cavity of the support member.

[0037] The at least one end member may comprise a first end member and a second end member. The first end member may have a port, particularly in which an on-tank valve is arranged or such a valve is connected or connectable thereto. The fuel / gas / hydrogen may be accessed by means of the on-tank valve, i.e. introduced (filling) into the tank and withdrawn (discharged) therefrom. The second end member may have a port, particularly in which port a thermal pressure relief device is arranged or such a device is connected or connectable thereto. The thermal pressure relief device may include means for releasing the stored fuel / gas / hydrogen upon an internal pressure exceeding a pressure threshold value. This enhances safety. The on-tank valve and the pressure relief device may be located on the two ports provided by the two end members, thereby being located on two respective ends of the entire gas flow path o inside the hydrogen tank.

[0038] The at least one end member, particularly the first end member and / or the second end member, may comprise a further cylindrical protrusion being engaged in a respective end of a tube. The further cylindrical protrusion may be designed similar to the cylindrical protrusion(s) of the coupling members. The further cylindrical protrusion may comprise a further gasket. The further gasket may be designed similar to the gasket equipping the coupling members.

[0039] The at least one end member and the coupling member(s) may be arranged on one side or end of the tubes in a row, especially in parallel to the support member. The at least one end member and the coupling members (s) may be in surface contact with each other to provide a stable arrangement. Thus, the at least one end member and / or the coupling members (s) may comprise particularly parallel contact surfaces.

[0040] Further, the invention also relates to a mobile application or mobile apparatus, for example a land vehicle, a sea ship or airborne vehicle, an airplane or the like, that uses hydrogen as a fuel. The mobile application or mobile apparatus may be provided with the hydrogen tank as described herein which is configured for storing hydrogen as fuel for powering an onboard engine.

[0041] Brief Description of the Drawings

[0042] Further details and advantages of the present invention will be apparent from the following detailed description of several not limiting embodiments with reference to the attached drawings, wherein:

[0043] Fig. 1 is a perspective exploded view of a hydrogen tank

[0044] Fig. 2 is a perspective view of the hydrogen tank in a longitudinal section;

[0045] Fig. 3 is a top view of one end of the hydrogen tank in the longitudinal section; and

[0046] Fig. 4 is a side view of the hydrogen tank which is cut in a cross section.

[0047] Description of Preferred Embodiments

[0048] Fig. 1-4 show an embodiment of the present tank 1 in different sections and views. The tank 1 is adapted to store pressurized fuel, namely hydrogen (i.e. H2 in gas state) and is therefore herein referred to as hydrogen tank.

[0049] With particular reference to Figs. 1 and 2, the hydrogen tank 1 comprises a plurality of tubes 10, namely two or more tubes 10, particularly here three tubes 10, for containing hydrogen. The tubes 10 are arranged parallel to each other (to their longitudinal direction), especially side by side. As will be understood, the longitudinal direction corresponds to the tube axis, parallel to axis X. The tubes 10 are arranged side by side in one plane, i.e. their respective axes are located in one plane (here parallel to plane X,Y). Direction Y may thus be referred to as the width direction.

[0050] Each of the tubes 10 has a liner 12 that is surrounded by a composite shell 13. The liner is metallic, but could be made from plastic material. The composite shell 13 surrounding the liner 12 comprises circumferentially wound impregnated filaments, a few filaments being represented symbolically at 14 for the sake of exemplification. The filaments 14 are wound substantially unidirectionally to bear hoop stress, with an angle between 80 and 90° with respect to the longitudinal direction (X).

[0051] The term “winding angle” defines the angle between the longitudinal axis (X) of the tube and the projection of the filaments onto the longitudinal plane. Coupling members 20 are arranged to close the tube ends. In the present embodiment, two coupling members 20 are provided of which one is arranged on one end 11 of the tubes and the other is arranged on another end 1 T. Each coupling member 20 is configured to fluidly couple two adjacent tubes 10. The coupling members 20 are arranged to serially connect all the tubes 10. A first end member

[0052] 30 and a second end member 31 are also provided on the ends 11 , 1 T of the tubes 10. The end members 30 are used to close tube ends that are not coupled by coupling members 20.

[0053] Referring to Fig.2, starting from the tube end 11 (on the left), the first two tubes are coupled by one coupling member 20 and the third tube end is closed by end member 30. On the opposite end 1 T, the first tube is closed by end member 31 and the two other tubes by one coupling member 20.

[0054] In this way, starting from the first end member 30 a meandering flow path for hydrogen is provided, which path ends at the second end member 31 , cf. particularly Fig. 2.

[0055] Each end member 30, 31 of the present embodiment has a respective port 32, 33, one of which is equipped with an on-tank valve (for filling and dispensing gas) and the other with a thermal pressure relief device (safety device), which are not shown here.

[0056] As can be observed, at the left side 11 , the outer shapes of the end member 30 and adjacent coupling member 20 are such that they are in surface contact, both having parallel contact surfaces which are in contact to each other. The same is true for end member 31 and the neighboring coupling member 20.

[0057] Furthermore, each end member 30, 31 is rigidly coupled to its adjacent coupling member 20, particularly via a support member 50, 51 . The support members 50, 51 are configured to be coupled to the coupling members 20 and the end members 30,

[0058] 31 by means of a dovetail joint forming a positive fit joint. The dovetail joint can be seen in a separated state in Fig. 1 and in an assembled state in Fig. 4. The support members 50, 51 are arranged on opposite ends 11 ,11’ of the plurality of tubes 10, cf. Fig. 4. The end members and coupling members are provided, on a side opposing the tubes, with protrusion extending in the width direction and having a dovetail cross-section. Each support member spans over the entire plurality of tubes and is provided on an inner side (facing the tubes) with a dove-shaped groove in which the corresponding protrusions of the end members and coupling members are engaged.

[0059] With particular reference to Fig. 1 , a longitudinal composite shell 40 is provided that is configured to be arranged around all of the tubes 10, the coupling members 20, the end members 30, 31 and the support members 50, 51. Said components, after assembly, can be inserted into the longitudinal composite shell 40, in this case substantially perpendicular to the longitudinal direction. The longitudinal composite shell 40 comprises resin impregnated wound filaments 41 (one filament 41 being symbolically shown for the sake of exemplification) arranged substantially along (parallel) to the longitudinal direction. The filaments 41 are wound substantially unidirectionally to bear longitudinal stress.

[0060] Hence in this embodiment, the composite shell 40 is prefabricated (produced as a separate component in advance of assembly) and is thus fitted over the assembly of the gas storage assembly formed by the tubes 10, coupling members 20, end members 30, 31 and support members 50, 51. Alternatively, the composite shell could be formed over the gas storage assembly.

[0061] With particular reference to Fig. 1 , the longitudinal composite shell 40 has two substantially planar sections 40.1 along the longitudinal direction and two substantially curved ends 40.2 connecting the two substantially planar sections 40.2, particularly which ends are configured to be in contact with the support members 50, 51. Particularly, in the width direction, the longitudinal composite shell 40 is open on at least one side, here at both sides. The openings could however be closed by side panels.

[0062] It may further be noted that the use the composite shell 40 designed to withstand axial / longitudinal loads allows assembling the coupling members 20 and end members 30, 31 without fixing them. That is the coupling members 20 and end members 30, 31 are engaged into the tube ends and are kept in place by the composite shell 40. There is no need for welding I brazing I gluing at the tube I coupling member interface, hence avoiding a rigid connection that transfers mechanical stress. The composite shell 13 for the tubes and the longitudinal composite shell 40 are here conveniently manufactured by filament winding technology (or other technology), wherein resin impregnated endless filaments are wound around the preformed liner in case of shell 13 or around a winding core for the longitudinal shell. In case of the shell 13 the resin is preferably a thermosetting resin, although a thermoplastic polymer resin is also possible. For the longitudinal shell 40 a thermoplastic polymer is preferred for recyclability, although a thermosetting resin is also possible.

[0063] With particular reference to Figs. 1 and 2, each of the coupling member 20 is formed as a body having a base portion 21 with two cylindrical protrusions 22, each of which cylindrical protrusion 22 is configured to be engaged in a respective end 11 ,1 T of a tube 10. The cylindrical protrusions 22 present a concave surface facing the inside of the tube 10. The coupling members 20 are for example made of metal, in particular aluminum (alloy).

[0064] With respect to the composition of the tubes 10, Fig. 3 illustrates that the liner 12, which consist of an aluminum alloy, is surrounded by a wound layer of resin impregnated filaments (e.g. glass or carbon fibers embedded in a thermoset resin, e.g. epoxy resin) forming the composite shell 13. In a radial direction, the shell 13 is thicker than the liner 12, e.g. by 200 % or more. The shell 13 is wound directly on (and bonded to) the liner 12. Due to the unidirectional orientation of the filaments 14 in the circumferential direction, the tubes 10 are mainly configured for bearing hoop stress or circumferential stress.

[0065] With reference to Fig. 3, for example, the coupling members 20 have a channel 26 extending between the two cylindrical protrusions 22 of a respective coupling member 20, particularly the respective concave surface, in order to fluidly couple the two adjacent tubes 10. Each channel 26 has been formed by means of two bores extending from a respective cylindrical protrusion 22 and overlapping substantially in a center of the respective coupling member 20 in its base portion 21 . The bores are arranged oblique to the longitudinal direction and particularly originate from respective concave surfaces, cf. particularly Fig. 2.

[0066] Particularly in view of Figs. 3 and 4, a gasket 2 is provided that is configured to seal between each cylindrical protrusion 22 of the coupling member 20 and the respective tube 10. Any appropriate type of gasket may be used, adapted to withstand pressure of several hundred bars. Here, each gasket 2 has two gasket components 2.1 , 2.2. of annular shape, particularly axially adjacent. For example, one gasket component is an elastomeric ring 2.1 and the second gasket component is a rigid plastic support ring 2.2 (or couple of support rings) proximal to shoulder 27. The respective gasket 2 is arranged at the periphery of the cylindrical protrusion 22 in a circumferential recess of the cylindrical protrusion 22, here formed by a shoulder 27. The gasket 2 is configured to engage with an inner surface 17 of the respective tube 10, i.e. with the liner. A diameter 25 of the cylindrical protrusions 22 is substantially equal to an inner diameter 15 of the tubes 10. The diameters 15, 25 are e.g. of 100 mm.

[0067] Line IV-IV in Fig. 3 indicates the position of the section shown in Fig. 4. Here, it can be seen that the first and second support members 50, 51 , have a general beam form with the inner side 50.1 , 51 .1 , joining the end members and coupling members, and an opposite outer side 51.1 , 52.1 with a rounded shape configured for facing a corresponding inside surface 42 of the longitudinal composite shell 40. The rounded shape is convex and configured to bear against the inside surface 42, particularly at the (concave) curved ends 40.2, providing a surface contact for supporting axial loads. The support members 50, 51 are furthermore hollow by way of including at least one cavity, in this case two cavities, which comprise a substantially rounded or roundish cross-sectional shape, cf. Fig. 4 at the top and at the bottom and adjacent to the positive fit joint or dovetail joint. The support members 50, 51 are covered by respective covers 52, especially to close the cavities. The covers 52 provide axial blocking of the coupling members 20 and the end members 30, 31 as well as lateral protection.

[0068] It may be noted that whereas in the Figs the composite shell 40 is represented as a monolithic component extending over the entire width of the tank assembly 10, in an alternative embodiment the composite shell could comprise a plurality loops forming composite strips of longitudinally wound filaments, there being at least one composite strip per tube. In such case the individual loops can be contiguous in width direction, or spaced from one another.

[0069] It remains to be noted that whereas the shown tank 1 comprises three tubes 10, it could comprise more tubes, e.g. 4, 5, or 6 and more. In such case, in the spirit of this embodiment, tube ends would, as here, only be fitted at both sides with coupling members 20 and end members 30, 31 , the coupling members being connected to the tubes to provide a serial connection.

[0070] For example, with 4 tubes, there may be two adjacent coupling members on one side, and on the other side the two central tubes could be connected by a coupling member, and the two outer tubes plugged by the end members.

[0071] For example, with 5 tubes, there may be on each side of the tubes two adjacent coupling members and one end member.

Claims

Claims1. A tank (1 ) configured for pressurized fuel, in particular gaseous fuel such as hydrogen, comprising: a plurality of tubes (10) for containing the pressurized fuel, arranged parallel to one another in a longitudinal direction, each having a liner (12) surrounded by a composite shell (13); coupling members (20) arranged at at least one end (11 ) of each tube (10); and a longitudinal composite shell (40) arranged around the plurality of tubes (10) and around the coupling members (20) to bear longitudinal loads applied on the coupling members (20); characterized in that each coupling member (20) is configured to fluidly couple two adjacent tubes (10), the coupling members (20) being arranged to serially connect all the tubes (10).

2. The tank (1 ) as claimed in claim 1 , wherein each one of the coupling members (20) comprises a base portion (21 ) with two cylindrical protrusions (22), each cylindrical protrusion (22) being engaged in a respective end (11 ) of a tube (10), a channel (26) being arranged in each coupling member (20) to extend from one cylindrical protrusion (22) to the other cylindrical protrusion (22) to fluidly couple two adjacent tubes (10).

3. The tank (1 ) as claimed in any of the preceding claims, wherein each one of the coupling members (20) comprises or is made of metal, especially an aluminum alloy, in particular cast aluminum alloy.

4. The tank (1 ) as claimed in claim 2 or 3, comprising a gasket (2) sealing between each cylindrical protrusion (22) of the coupling member (20) and the respective tube (10).

5. The tank (1 ) as claimed in the preceding claim, wherein the gasket (2) is arranged at the periphery of each cylindrical protrusions (22), preferably in a circumferential recess (27), and engages with an inner surface (17) of the respective tube (10).

6. The tank (1 ) as claimed in any of claims 2 to 5, wherein the cylindrical protrusions (22) have a diameter (25) substantially equal to an inner diameter (15) of each of the plurality of tubes (10).

7. The tank (1 ) as claimed in any of the preceding claims, wherein the composite shell (13) surrounding the liner (12) comprises circumferentially wound resin impregnated filaments (14).

8. The tank (1 ) as claimed in any of the preceding claims, wherein the longitudinal composite shell (40) comprises wound resin impregnated filaments (41 ) arranged substantially along the longitudinal direction.

9. The tank (1 ) as claimed in any of the preceding claims, wherein the tubes (10) comprise an / the inner diameter (15) of at least 100 mm, 150 mm or 200 mm.

10. The tank (1 ) as claimed in any of the preceding claims, comprising at least one end member (30, 31 ) closing an end (11 ) of a respective tube (10) and configured for providing a port (32, 33) to the stored pressurized fuel, the longitudinal composite shell (40) additionally surrounding the at least one end member (30, 31 ).

11. The tank (1 ) as claimed in the preceding claim, comprising a support member (50, 51 ) being coupled to the coupling member(s) (20) and / or the at least one end member (30, 31 ), in particular by means of a positive fit joint, especially a dovetail joint.

12. The tank as claimed in any of the preceding two claims, comprising a second support member (51 ), wherein the support members (51 , 52) are arranged on opposing ends (11 ) of the plurality of tubes (10).

13. The tank (1 ) as claimed in one of the preceding three claims, wherein the support member(s) (50, 51 ) has / have a round shape facing a corresponding inside surface (42) of the longitudinal composite shell (40).

14. The tank (1 ) as claimed in any of the preceding four claims, wherein the support member(s) (50, 51 ) is / are hollow.

5. The tank (1) as claimed in any of the preceding claims, comprising a first end member (30) and a second end member (31 ) of the at least one end member (30, 31 ), the first end member (30) having a port (32) in which an on tank valve is arranged, and the second end member (31 ) having a port (33) in which a thermal pressure relief device is arranged, particularly the at least one end member (30, 31 ) comprising a further cylindrical protrusion (35) being engaged in a respective end (11 ) of a tube (10).

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