Multilayer pipe and applications of multilayer pipe

Abstract

The invention relates to a multilayer pipe (1) for conducting a fluid containing hydrogen. The multilayer pipe (1) has at least one inner layer (2) forming a containment space (7) for the fluid, a barrier layer (3) surrounding the inner layer (2), an intermediate layer (4) surrounding the barrier layer (3), a pressure carrier layer (5) surrounding the intermediate layer (4) and an outer layer (6) surrounding the pressure carrier layer (5). According to the invention, the intermediate layer (4) is manufactured from a mixture of a thermoplastic elastomer (TPE) and an adhesion promoter or from a mixture of a thermoplastic vulcanizate (TPV) and an adhesion promoter. Furthermore, the invention also relates to the use of a multilayer pipe (1) in a medium-pressure system.

Description

Technical Field

[0001] This invention relates to a multilayer tube for guiding hydrogen-containing fluids, and an application of the multilayer tube. Background Technology

[0002] Hydrogen is becoming increasingly important for energy production. Typically, hydrogen is stored in tanks under high pressure. For example, the pressure in a vehicle's hydrogen tank can reach several hundred bar, and in some cases, up to 700 bar. To guide hydrogen or hydrogen-containing fluids from the tank to the point of use, such as a fuel cell, the pressure of the fluid (pure hydrogen or hydrogen-containing fluid) is reduced in a pressure regulator, typically to less than or equal to 30 bar. Further distribution of the fluid to the point of use is carried out via a medium-pressure system. Traditionally, medium-pressure systems consist of metal conduits supplemented by elastomeric hoses with braided reinforcements to compensate for installation and manufacturing tolerances. This multi-part conduit structure results in high installation costs. Furthermore, both the metal conduits and the elastomeric hoses with braided reinforcements are heavy.

[0003] Multilayer pipes for fuel conduits, i.e., conduits for gasoline, diesel, kerosene, etc., are known in general terms from the prior art. Therefore, a multilayer fuel conduit is known from DE 10 2011 089 616 A1. This fuel conduit has a polyethylene inner layer, a polyamide outer layer, and a barrier layer disposed between the inner and outer layers, which can be made of ethylene-vinyl alcohol copolymer (EVOH). An adhesion promoter layer can be disposed adjacent to the barrier layer. While the polyethylene inner layer prevents the leaching of oligomers, it only has low stability, pressure resistance, and temperature resistance. To improve stiffness and thus pressure resistance, the outer layer is made of polyamide, which also leads to increased manufacturing costs.

[0004] EP 1 362 890 A1 describes an alternative embodiment of a multilayer hose for automotive conduits. The outer layer of this hose has greater rigidity than all the inner layers. The outer layer is made of polyamide. The inner layers are made of thermoplastic elastomer. In this multilayer hose, stability, pressure resistance, and temperature resistance also depend decisively on the thickness of each layer. Furthermore, hydrogen can penetrate the walls of the multilayer hose and can escape from it. Summary of the Invention

[0005] The object of this invention is to provide a multilayer tube for guiding hydrogen-containing fluids, which reduces hydrogen permeation, has improved flexibility and improved compressive strength, and has a minimal weight and reduced assembly costs. Furthermore, the object of this invention is to provide applications for such a multilayer tube.

[0006] According to the present invention, this objective is achieved by a multilayer tube according to claim 1. The multilayer tube comprises at least one inner layer forming a fluid-containing space, a barrier layer surrounding the inner layer, an intermediate layer surrounding the barrier layer, a pressure carrier layer surrounding the intermediate layer, and an outer layer surrounding the pressure carrier layer. Furthermore, the present invention proposes that the intermediate layer is made of a mixture of thermoplastic elastomer (TPE) and an adhesive, or a mixture of thermoplastic vulcanizate (TPV) and an adhesive. Since the multilayer tube according to the present invention has multiple layers, the different layers can perform different functions. Thus, the inner layer forms a fluid-containing space. The barrier layer acts as a barrier to prevent hydrogen escape, i.e., to reduce hydrogen permeation. The pressure carrier layer provides stability of the multilayer tube to the working pressure of the fluid. Therefore, the compressive strength is increased, and the multilayer tube is able to prevent rupture. The outer layer protects the pressure carrier layer from external influences. If the intermediate layer is made only of thermoplastic material, then in particular the pressure carrier layer and the barrier layer may be able to move relative to each other. In contrast, the intermediate layer, composed of a mixture or composite of thermoplastic materials, namely TPE or TPV, and an adhesive, surprisingly results in adhesion between this intermediate layer and the layers directly adjacent to it, such as barrier layers and / or pressure carrier layers. This establishes an adhesive bond between the intermediate layer and the adjacent layers without additional manufacturing costs. Simultaneously, this structure allows the use of lightweight materials such as TPE and TPV, reducing the weight of multilayer tubing and also increasing its flexibility. This flexible multilayer tubing can compensate for installation and manufacturing tolerances during installation in medium-pressure systems without requiring additional conduit sections made of other materials, thus reducing installation costs.

[0007] Specifically, it is proposed that the inner layer at least partially, and preferably completely, surrounds the receiving space. Furthermore, it may be provided that a barrier layer partially or completely surrounds the inner layer, and / or an intermediate layer partially or completely surrounds the barrier layer, and / or a pressure carrier layer partially or completely surrounds the intermediate layer, and / or an outer layer partially or completely surrounds or encloses the pressure carrier layer. Preferably, each layer is completely surrounded or enclosed by the layer surrounding it. It should be noted that the thickness of each layer (i.e., the inner layer, barrier layer, intermediate layer, pressure carrier layer, and outer layer) is preferably substantially constant along the circumference of the multilayer tube.

[0008] In the context of this invention, "hydrogen-containing fluid" should be understood as a fluid in which H2 molecules are present. This can be, for example, pure hydrogen in gaseous and / or liquid state. However, in the sense of this invention, a mixture of hydrogen and one or more other fluids is also a hydrogen-containing fluid.

[0009] When the containment space has a smooth, especially circular, cross-section, fluid can flow through it particularly efficiently. It is also advantageous for the inner layer to have a smooth, especially circular, cross-section. Furthermore, it is advantageous for the barrier layer and / or the intermediate layer and / or the pressure carrier layer and / or the outer layer to have a smooth, especially circular, cross-section. Preferably, the inner layer, barrier layer, intermediate layer, pressure carrier layer, and outer layer are arranged concentrically around a common center, more preferably concentrically around the center of the containment space or around the centroid of the cross-section of the containment space.

[0010] Specifically, it is proposed that the barrier layer exhibits a maximum strength of 20 Ncm / operating meter under overpressure of 90°C and 21 bar. 3 Hydrogen permeation per hour. Hydrogen permeation was determined according to Test 6.7 of ISO 12619-14. The hydrogen permeation was measured using "Ncm". 3 To describe a standard cubic centimeter, that is, one cubic centimeter contained in 1 cm³ at 1.01325 bar and 273.15 K (0°C). 3 The amount of fluid in a volume.

[0011] Specifically, it is proposed that the pressure carrier layer has a burst pressure of at least 63 bar at 90°C. The burst pressure at 90°C is determined according to Test 6.2 of ISO 12619-14. If the pressure carrier layer has a burst pressure of at least 63 bar at 90°C, durable resistance to a maximum operating pressure of 30 bar can be guaranteed. Additionally or alternatively, it is proposed that the pressure carrier layer has a burst pressure of at least 84 bar at room temperature. The burst pressure at room temperature is similar to that determined by Test 6.2 of ISO 12619-14.

[0012] To improve sustainability, TPE or TPV with thermoplastic recyclables, such as recycled polypropylene, can be used.

[0013] Thermoplastic vulcanizates can have a matrix composed of thermoplastic plastics, such as polypropylene (PP). Preferably, rubber, particularly ethylene propylene diene monomer (EPDM), is introduced into the matrix. Such TPVs are known, for example, under the trade name Santoprene (a trademark of Celanese International).

[0014] In particular, the outer layer has an adhesion promoter, preferably the same adhesion promoter as the intermediate layer. Alternatively or additionally, it is particularly proposed that the outer layer forms an adhesive bond with the layer directly adjacent to the outer layer, preferably with the pressure carrier layer. The adhesive bond can be formed by chemical bonding, for example by melting. Preferably, the adhesive bond between the outer layer and the pressure carrier layer can, for example, resist relative movement between the outer layer and the pressure carrier layer, a resistance greater than the resistance of the adhesive bond between the intermediate layer and the layer adjacent to the intermediate layer, for example, the pressure carrier layer.

[0015] In an advantageous embodiment of the invention, a barrier layer is disposed directly on the inner layer, and / or an intermediate layer is disposed directly on the barrier layer, and / or a pressure carrier layer is disposed directly on the intermediate layer, and / or an outer layer is disposed directly on the pressure carrier layer. In particular, if the barrier layer is disposed directly on the inner layer, the intermediate layer is disposed directly on the barrier layer, the pressure carrier layer is disposed directly on the intermediate layer, and the outer layer is disposed directly on the pressure carrier layer, the weight of the multilayer tube can be reduced while maintaining high pressure resistance. The wall thickness of the multilayer tube is then obtained at least by the sum of the inner layer thickness, the barrier layer thickness, the intermediate layer thickness, the pressure carrier layer thickness, and the outer layer thickness.

[0016] Preferably, the outer layer is not surrounded by any other layer.

[0017] In particular, the adhesive for the intermediate layer is a polyolefin-based adhesive. With a polyolefin-based adhesive, adhesion to both the barrier layer and the pressure carrier layer can be achieved simultaneously, especially adhesion to the fibers of the pressure carrier layer made of polyamide or polypropylene. Furthermore, it is advantageous to use a thermoplastic doped with maleic anhydride (MAH).

[0018] If the thermoplastic doped with maleic anhydride (MAH) is polyethylene (PE) or polypropylene (PP), the manufacturing cost of multilayer pipes can be further reduced. If the thermoplastic is low-density polyethylene (LDPE), preferably linear low-density polyethylene (LLDPE), the relationship between the flexibility and stiffness of the multilayer pipe can be improved. A known adhesion promoter is provided under the trade name Orevac 18341. Orevac is a trademark of SK FUNCTIONAL POLYMER Simplified Co., Ltd.

[0019] Surprisingly, it has been found that particularly good adhesion can be achieved if the adhesive used to set the intermediate layer has an intermediate layer weight percentage of at least 35%, especially at least 40%, preferably at least 50%, and / or at most 60%. It has proven particularly advantageous to use a mixture for the intermediate layer consisting of 50% by weight of the adhesive and 50% by weight of thermoplastic vulcanizate.

[0020] To further reduce manufacturing costs, the outer layer can be made of the same material as the middle layer. Furthermore, it is advantageous to use TPV for the outer layer because TPV has lower hygroscopicity compared to many other thermoplastics. In particular, when using TPV to manufacture the outer layer, very good resistance to external media, such as zinc chloride, is obtained.

[0021] The pressure carrier layer is used to prevent the multilayer tube from deforming due to excessively high fluid operating pressure. To further improve resistance to fluid operating pressure, the pressure carrier layer may be provided with fibers, and the fibers may be polyamide (PA) and / or polypropylene (PP). In particular, the pressure carrier layer is made of polyamide fibers (PA) or polypropylene fibers (PP). A mixture of PA and PP fibers may also be provided. Polyamide fibers may also be provided additionally or alternatively. Furthermore, it is preferred that the fibers have a core and an outer sheath, wherein the core and sheath are preferably made of different materials. For example, a portion of the fibers (preferably all fibers) may have a core made of polyester (PES), and the outer sheath may be made of polypropylene. By using polypropylene, an adsorbent-free outer layer may be provided, for example, an outer layer composed solely of TPV. In particular, the pressure carrier layer may be provided with coated polyamide fibers, and the polyamide fibers may be discharged, for example, activated by corona discharge, before being coated with the outer layer. For connection with the outer layer, in the case of the pressure carrier layer being discharged, an outer layer composed of a mixture of TPV and an adsorbent may be provided. Alternatively or additionally, particularly, the pressure carrier layer may have PA fibers with silane slurry.

[0022] If the pressure carrier layer is alternatively or additionally configured as a braided fabric, the attachment of the pressure carrier layer can become easier. In particular, the braided fabric is interwoven fibers. Preferably, the braided fabric is a biaxial braided fabric, and more preferably, a 2D biaxial circular braided fabric. For example, the individual fibers of the braided fabric can have polyamide fibers and / or polypropylene fibers. For example, the braided fabric is configured to be made of polypropylene fibers and polyamide fibers, especially parallel polypropylene fibers and polyamide fibers. Braided fabrics made of polyamide fibers are commercially common. The polypropylene fibers can be attached to an intermediate layer having polypropylene, for example, after or during the extrusion process. To improve the stability of the multilayer tube, the braided fabric is particularly configured to have a coverage of at least 50%, preferably at least 80%, further preferably at least 100%, and most preferably 100%. The higher the coverage, the less material can penetrate the adjacent layers (e.g., the intermediate layer) of the pressure carrier layer. At a coverage of 100%, the braided fabric is substantially, preferably completely, without voids. Alternatively or additionally, particularly, the braided fabric has a braiding angle of less than 90°, preferably between 15° and 75°, more preferably between 30° and 60°, more preferably between 45° and 60°, and most preferably 54°. This braiding angle extends between the longitudinal axis of the multilayer tube, especially the intermediate longitudinal axis, and the fibers of the braided fabric.

[0023] To achieve sufficient rigidity, the pressure carrier layer can be configured to have a layer thickness of at least 0.2 mm. If the pressure carrier layer has a maximum layer thickness of 0.4 mm, the wall thickness of the multilayer tube can be reduced. Preferably, the pressure carrier layer has a layer thickness between 0.2 mm and 0.4 mm, preferably 0.4 mm. If the pressure carrier layer is a braid, the layer thickness can be at least one layer thickness of the braid, for example, exactly one layer thickness or exactly two layer thicknesses. In the case of two layer thicknesses, the braid is doubly placed around the intermediate layer. If one layer of the braided material of the pressure carrier layer surrounds the intermediate layer, then there is one layer thickness of the pressure carrier layer.

[0024] To reduce hydrogen permeation, a barrier layer can be manufactured using ethylene-vinyl alcohol copolymer (EVOH). EVOH provides good hydrogen barrier properties and is thermoplastically processable. The thermoplastic processability of at least the intermediate layer and pressure carrier layer simplifies the manufacture of multilayer tubes. For increased flexibility, the barrier layer can be made from a mixture of ethylene-vinyl alcohol copolymer (EVOH) and an elastic thermoplastic, preferably a thermoplastic elastomer (TPE). If the ethylene-vinyl alcohol copolymer (EVOH) has an ethylene content of no more than 30 mol%, preferably no more than 27 mol%, the cost of preparing the barrier layer can be reduced while providing sufficient barrier properties against hydrogen permeation. To improve adhesion between the barrier layer and the intermediate layer, it is preferable that the barrier layer is made using EVOH and the intermediate layer has MAH as an adhesion promoter.

[0025] To avoid adversely affecting the blocking ability of the barrier layer, the barrier layer may be configured to have a thickness of at least 0.1 mm. If, in particular, the barrier layer is configured to have a thickness of up to 0.3 mm, preferably up to 0.2 mm, the weight of the multilayer tube can be reduced, and the flexibility of the multilayer tube can be improved. Preferably, the barrier layer has a thickness between 0.1 mm and 0.2 mm, more preferably 0.1 mm.

[0026] Specifically, the inner layer forms a protective layer for the barrier layer. This is particularly important when using EVOH to manufacture the barrier layer, as it is crucial to prevent the barrier layer from being exposed to humid hydrogen. When EVOH is exposed to humid hydrogen, the humidity level in the EVOH increases, and the barrier capacity of the EVOH decreases, thus reducing the barrier capacity of the barrier layer. Therefore, the inner layer can improve the service life of the barrier layer, and consequently, the service life of the multilayer tube.

[0027] If the inner layer is made of the same material as the middle layer, manufacturing costs can be further reduced. Furthermore, if the outer layer is made of the same material as both the middle and inner layers, manufacturing costs can be further reduced.

[0028] Alternatively, the inner layer can be made of a conductive material. This conductive inner layer serves as a protective layer for the pressure carrier layer and enables the conduction of electrostatic charges. Therefore, the safety of multilayer tubes and medium-voltage systems using multilayer tubes is increased. Specifically, in the installed state, for example in a medium-voltage system, the multilayer tube is electrically connected to a grounding point (ground wire). For this purpose, in the installed state, each of the two ends of the multilayer tube can be connected to a conductive plug connector, and this plug connector is connected to a ground wire, such as the grounding point of a vehicle.

[0029] If the inner layer is made of a conductive-doped and adhesion-modified material, the adhesion between the inner layer and the barrier layer can be improved. In particular, the inner layer is made of a conductive-doped and adhesion-modified thermoplastic vulcanizate (TPV). For this purpose, materials known, for example, under the trade name Nylabond (a registered European trademark of Miller Waste Mills, Inc., operating under the alias RTP Company) can be used. Additionally or alternatively, it is preferred that the inner layer has carbon material fibers, preferably carbon nanofibers, and / or carbon black, such as conductive carbon black. Preferably, the inner layer is made of adhesion-modified TPV, which has carbon black, such as conductive carbon black; more preferably, the TPV is mixed with carbon black, such as conductive carbon black. For example, the carbon nanofibers can be configured as carbon nanotubes.

[0030] Specifically, the conductive inner layer is configured to have a maximum resistance of less than 1 M ohm per meter of conductive length. To determine the maximum resistance, test 6.6 according to ISO 12619-14 is used. This measurement is applied to multilayer tubes, including the plug with the mating connection.

[0031] If the inner layer is configured to have a thickness of at least 0.2 mm, and particularly a maximum thickness of 0.4 mm, material consumption for multilayer tubes can be reduced. Specifically, the inner layer is configured to have a thickness between 0.2 mm and 0.4 mm. Surprisingly, it has been found that if the inner layer is configured to have a thickness of 0.3 mm, low material consumption can be achieved while providing sufficient protection for the barrier layer, and potentially sufficient conductivity can also be achieved.

[0032] In an improved embodiment of the invention, the multilayer tube is proposed to have an outer diameter between 19.7 mm and 21 mm, particularly 20.3 mm. Advantageously, the multilayer tube has a circular outer circumference. Alternatively or additionally, the multilayer tube has an inner diameter between 12.7 mm and 13 mm. This simplifies its interaction with commercially available plug-in connections for hydraulic conduits with a nominal width of DN 12 mm. In particular, the multilayer tube has a circular inner circumference. Preferably, the inner circumference of the multilayer tube coincides with the inner circumference of the inner layer. Especially in the case of a multilayer tube with a circular cross-section, the outer diameter is derived from twice the thickness of all layers and the inner diameter of the accommodating space (the inner diameter of the multilayer tube). In the case of only one inner layer, one barrier layer, one intermediate layer, one pressure carrier layer, and one outer layer, the outer diameter is derived from the sum of the inner diameter of the multilayer tube and twice the sum of the thicknesses of the inner layer, the barrier layer, the intermediate layer, the pressure carrier layer, and the outer layer. Furthermore, it should be noted that, advantageously, the thickness of a layer, and especially the thickness of each layer within each layer, is substantially constant along the orientation of the respective layer. "Substantially" in the context of this invention should also be understood to include deviations due to the chosen manufacturing method.

[0033] Surprisingly, multilayer tubes with a total layer thickness of at least 3.5 mm, especially at most 4 mm, preferably between 3.5 mm and 4 mm, and preferably 3.8 mm, can particularly achieve multilayer tubes that satisfy the aforementioned compressive strength requirements while also being flexible enough to compensate for tolerances during assembly. The total layer thickness is generated by the sum of the maximum layer thicknesses of each layer in the multilayer tube. Especially in the case of multilayer tubes with constant layer thicknesses, the total layer thickness is derived from the sum of all layer thicknesses. For the case of having only one inner layer, one barrier layer, one intermediate layer, one pressure carrier layer, and one outer layer, the total layer thickness is derived from the sum of the inner layer thickness, the barrier layer thickness, the intermediate layer thickness, the pressure carrier layer thickness, and the outer layer thickness.

[0034] For example, the intermediate layer is configured to have a thickness of at least 1 mm. More particularly, the intermediate layer is configured to have a thickness of up to 3 mm. Preferably, the intermediate layer has a thickness of 1 mm to 3 mm, preferably 2 mm. For example, the intermediate layer may have a thickness of 2.7 mm.

[0035] The outer layer also affects the flexibility and stability of the multilayer tube. Therefore, it can be additionally or alternatively provided that the outer layer has a thickness of at least 0.5 mm, particularly at most 1 mm, preferably between 0.5 mm and 1 mm, and more preferably 1 mm. For example, the outer layer may have a thickness of 0.7 mm.

[0036] Furthermore, this objective is achieved through the application of the multilayer tube of the present invention in a medium-pressure system according to claim 16. The foregoing embodiments concerning the multilayer tube according to the present invention, particularly its implementation and advantages, also apply to the application of the multilayer tube in a medium-pressure system, and vice versa. Medium-pressure systems are particularly suitable for fuel cells, and preferably for hydrogen vehicles. In summary, the application of the multilayer tube in a medium-pressure system enables the provision of a medium-pressure system with reduced hydrogen permeability, improved flexibility, and improved pressure resistance. Simultaneously, the medium-pressure system exhibits reduced weight and reduced assembly costs.

[0037] The present invention also provides a method for manufacturing a multilayer tube for guiding hydrogen-containing fluids. The method includes the following steps: - Construct an inner layer that forms a space for containing fluid. - Surround the inner layer with a barrier layer. - Surround the barrier layer with an intermediate layer. - The intermediate layer is surrounded by a pressure carrier layer, and - Surround the pressure carrier layer with an outer layer.

[0038] Furthermore, it is proposed that the intermediate layer is made of a mixture of thermoplastic elastomer (TPE) and an adhesive, or a mixture of thermoplastic vulcanizate (TPV) and an adhesive. Since the multilayer tubes according to the invention and the multilayer tubes manufactured by the method according to the invention have the same structure, all the embodiments and advantages previously described with respect to multilayer tubes also apply to this method, and vice versa. In particular, the method of the invention is a method for manufacturing the multilayer tubes of the invention.

[0039] In particular, at least the inner layer and / or the barrier layer and / or the intermediate layer are manufactured using an extrusion process, such as by means of co-extrusion. This method is known in practice. Furthermore, in particular, the pressure carrier layer is wound around the intermediate layer.

[0040] To enhance sustainability, the thermoplastic elastomer and / or thermoplastic vulcanizate are specifically configured to contain recycled components. In particular, the polyamide used in the manufacture of multilayer tubes is at least partially recycled polyamide, and / or the polypropylene used in the manufacture of multilayer tubes is at least partially recycled polypropylene.

[0041] According to a particularly preferred embodiment, a multilayer tube with a total layer thickness of 3.8 mm is provided. In this multilayer tube, the individual layers are selected according to the description in Table 1:

[0042] Table 1 Furthermore, the multilayer tube has a circular cross-section receiving space. The receiving space has an inner diameter of 12.7 mm, allowing the multilayer tube to mate with a conventional hydrogen port having an inner diameter of 13 mm. The multilayer tube according to this embodiment has a total circular outer diameter of 20.3 mm (12.7 mm + 2 x 3.8 mm).

[0043] Multilayer tubes with this structure are flexible, allowing for different routing options and compensating for installation or manufacturing tolerances. Furthermore, multilayer tubes according to this specific embodiment exhibit a burst pressure exceeding 84 bar at 90°C and exceeding 120 bar at room temperature, while maintaining low material consumption. This ensures durable resistance to a maximum operating pressure of 30 bar. Further experimentally determined characteristics of the multilayer tubes according to Table 1 are shown in Table 2 below:

[0044] Table 2 Surprisingly, this multilayer tube not only meets but exceeds the target values ​​for all measured parameters. This embodiment provides a multilayer tube that achieves a yield of less than 12 Ncm. 3 / h per meter of operation is significantly lower than the target of no more than 20 Ncm. 3 The maximum hydrogen permeability is [value missing] / h, indicating reduced hydrogen permeability. The burst pressure measured at room temperature and 90°C also significantly exceeds the requirements, thus the multilayer tube exhibits improved compressive strength. Furthermore, in this embodiment, the resistance per meter of conductive length, including the plug, is 0.1 MΩ / m, which is 10 times lower than the target value (less than 1 MΩ / m). These measurements can be achieved while reducing material consumption; therefore, the multilayer tube according to this embodiment not only has low weight but also remarkably high flexibility and stability. Attached Figure Description

[0045] Other advantageous designs of the invention are illustrated in the following drawings and dependent claims.

[0046] The attached diagram shows: Figure 1 The cross-section of the multilayer tube of the present invention is shown, and Figure 2 A detailed diagram of the braided fabric used for the pressure carrier layer of a multi-layer tube is shown. Detailed Implementation

[0047] As will be noted in the following description, the present invention is not limited to the embodiments, nor is it limited to all or more features of the described feature combinations. Rather, each individual sub-feature of each embodiment is meaningful to the subject matter of the invention independently of all other sub-features described therein, and also in combination with any features of other embodiments.

[0048] Figure 1 A cross-section of a multilayer tube for guiding hydrogen-containing fluids according to the present invention is shown. The multilayer tube is generally indicated by 1. The multilayer tube 1 is configured for use in medium-pressure systems.

[0049] The multilayer tube 1 includes an inner layer 2, a barrier layer 3, an intermediate layer 4, a pressure carrier layer 5, and an outer layer 6. These layers are arranged from the inside out such that the inner layer 2 forms a fluid-receiving space 7. Furthermore, the barrier layer 3 surrounds the inner layer 2, the intermediate layer 4 surrounds the barrier layer 3, the pressure carrier layer 5 surrounds the intermediate layer 4, and the outer layer 6 surrounds the pressure carrier layer 5. In this embodiment, the intermediate layer 4 is made of a mixture of thermoplastic vulcanizate (TPV) and an adhesion promoter. Alternatively, the intermediate layer 4 may also be made of a mixture of thermoplastic elastomer (TPE) and an adhesion promoter. In this embodiment, the fluid-receiving space 7 has a circular cross-section.

[0050] Furthermore, the barrier layer 3 exhibits a maximum of 20 Ncm / meter of operating pressure at 90°C and 21 bar overpressure. 3 / h hydrogen permeation. The pressure carrier layer 5 has durable resistance to at least 30 bar operating pressure and at least 84 bar burst pressure at room temperature, and at least 63 bar burst pressure at 90°C.

[0051] like Figure 1 As shown, barrier layer 3 is disposed directly on inner layer 2. Furthermore, intermediate layer 4 is disposed directly on barrier layer 3. Pressure carrier layer 5 is disposed directly on intermediate layer 4. Outer layer 6 is disposed directly on pressure carrier layer 5. Outer layer 6 is not surrounded by any other layers, thus exposing it directly to environmental influences.

[0052] The adhesive for the intermediate layer 4 is a polyolefin-based adhesive containing maleic anhydride (MAH). In this embodiment, the adhesive for the intermediate layer 4 is a thermoplastic doped with maleic anhydride (MAH), such as polyethylene (PE).

[0053] The adhesive of intermediate layer 4 has a share of at least 35% to a maximum of 60% by weight of the total weight of intermediate layer 4.

[0054] The middle layer 4 and the outer layer 6 are made of the same material.

[0055] The pressure carrier layer 5 has fibers 8 made of thermoplastic plastic. For example... Figure 2 As shown, fibers 8 are woven into a fabric 5a. The fibers 8 of the fabric 5a are arranged such that they form 100% coverage. The surface arranged under the fabric 5a, in the case of the multilayer tube 1, is the outer periphery 4a of the intermediate layer 4, and is completely (100%) covered by the fabric 5a. The fabric 5a has a weaving angle α. This weaving angle α extends between the longitudinal axis 1a of the multilayer tube 1 (preferably the central longitudinal axis of the multilayer tube 1) and the fibers 8.

[0056] As from Figure 1 As can be seen, the woven fabric 5a is disposed around the intermediate layer 4, and thus forms the pressure carrier layer 5. The thickness d5 of the pressure carrier layer 5 is between 0.2 mm and 0.4 mm. The pressure carrier layer 5 is formed by at least one layer of woven fabric 5a.

[0057] The pressure carrier layer 5 is disposed on the outer periphery 4a of the intermediate layer 4 on the outer side, while the barrier layer 3 is disposed on the inner periphery 4b of the intermediate layer 4 on the inner side. Both the pressure carrier layer 5 and the barrier layer 3 are adhesively attached to the intermediate layer 4. The barrier layer 3 is manufactured using ethylene-vinyl alcohol copolymer (EVOH). Furthermore, the barrier layer 3 has a layer thickness d3 between 0.1 mm and 0.3 mm.

[0058] It should be noted that the inner layer 2 can be made of the same material as the intermediate layer 4. Alternatively, the inner layer 2 can be made of a conductive material. In particular, the inner layer 2 has a resistance of less than 1 M ohms per meter of conductive length.

[0059] The inner layer 2 has a layer thickness d2, wherein the layer thickness d2 is between 0.2 mm and 0.4 mm.

[0060] Not only does the fluid-containing space 7 have a circular cross-section, but the multilayer tube 1 also has a circular cross-section. The multilayer tube 1 has an outer diameter 9 between 19.7 mm and 21 mm. The inner diameter 10 of the multilayer tube 1 is between 12.7 mm and 13 mm, which corresponds to the inner diameter 2a of the inner layer 2.

[0061] According to this embodiment, the total layer thickness d1 is formed by the sum of the layer thickness d2 of the inner layer 2, the layer thickness d3 of the barrier layer 3, the layer thickness d4 of the intermediate layer 4, the layer thickness d5 of the pressure carrier layer 5, and the layer thickness d6 of the outer layer 6. The total layer thickness d1 is at least 3.5 mm. The layer thickness d4 of the intermediate layer 4 is between 1 mm and 3 mm. The layer thickness d6 of the outer layer 6 is at least 0.5 mm and at most 1 mm.

[0062] This invention is not limited to the embodiments shown and described, but also includes all embodiments that serve the same purpose in the sense of this invention. It is explicitly emphasized that the embodiments are not limited to all features of the combination; rather, each individual sub-feature can be separated from all other sub-features and has inventive significance in itself. Furthermore, this invention is not limited to the feature combination defined in claim 1, but can also be defined by any other combination of specific features from all the generally disclosed individual features. This means that, in principle, any individual feature of claim 1 can be omitted, or replaced by at least one individual feature disclosed elsewhere in this application.

[0063] Explanation of reference numerals in the attached figures 1. Multilayer pipe 1a Longitudinal axis 2 Inner layer 2a Inner diameter 3. Barrier layer 4. Intermediate layer 4a Periphery 4b inner circumference 5. Pressure carrier layer 5a Woven fabrics 6 Outer layer 7. Capacity 8 Fibers 8a First Fiber 8b Second Fiber 9 Outer diameter 10 inner diameter α Weaving angle d1 Total layer thickness d2 Inner layer thickness d3 Barrier Layer Thickness d4 Intermediate layer thickness d5 Pressure carrier layer thickness d6 Outer layer thickness

Claims

1. A multilayer tube (1) for guiding hydrogen-containing fluid, comprising at least: The inner layer (2) forms a containment space (7) for the fluid. A barrier layer (3) surrounding the inner layer (2). The intermediate layer (4) surrounding the barrier layer (3). The pressure carrier layer (5) surrounding the intermediate layer (4), and The outer layer (6) surrounding the pressure carrier layer (5). in, The intermediate layer (4) is made of a mixture of thermoplastic elastomer (TPE) and adhesive, or a mixture of thermoplastic vulcanizate (TPV) and adhesive.

2. The multilayer tube (1) according to claim 1. Its features are, The barrier layer (3) is directly disposed on the inner layer (2), and / or the intermediate layer (4) is directly disposed on the barrier layer (3), and / or the pressure carrier layer (5) is directly disposed on the intermediate layer (4), and / or the outer layer (6) is directly disposed on the pressure carrier layer (5).

3. The multilayer tube (1) according to claim 1 or 2. Its features are, The outer layer (6) is not surrounded by any other layer.

4. The multilayer tube (1) according to any one of claims 1 to 3. Its features are, The adhesive of the intermediate layer (4) is a polyolefin-based adhesive, in particular, the adhesive has maleic anhydride (MAH), preferably, the adhesive is a thermoplastic doped with maleic anhydride (MAH).

5. The multilayer tube (1) according to claim 4. Its features are, The thermoplastic doped with maleic anhydride (MAH) is polyethylene (PE) or polypropylene (PP), especially low-density polyethylene (LDPE), and preferably linear low-density polyethylene (LLDPE).

6. The multilayer tube (1) according to any one of claims 1 to 5. Its features are, The adhesive of the intermediate layer (4) has a share of the weight of the intermediate layer (4), said share being at least 35% by weight, especially at least 40% by weight, preferably at least 50% by weight, and / or having a share of the weight of the intermediate layer (4) of up to 60% by weight.

7. The multilayer tube (1) according to any one of claims 1 to 6. Its features are, The outer layer (6) is made of the same material as the middle layer (4).

8. The multilayer tube (1) according to any one of claims 1 to 7. Its features are, The pressure carrier layer (5) has fibers, and the fibers have polyamide (PA) and / or polypropylene (PP), and / or The pressure carrier layer (5) is a woven fabric (5a), preferably, the woven fabric (5a) has a coverage of at least 50%, preferably at least 80%, more preferably at least 100%, and most preferably 100%, and / or Preferably, the woven fabric (5a) has a weaving angle (α) of less than 90°, preferably between 15° and 75°, more preferably between 30° and 60°, more preferably between 45° and 60°, and most preferably 54°.

9. The multilayer tube (1) according to any one of claims 1 to 8. Its features are, The pressure carrier layer (5) has a layer thickness (d5) of at least 0.2 mm, especially at most 0.4 mm, preferably between 0.2 mm and 0.4 mm, preferably 0.4 mm.

10. The multilayer tube (1) according to any one of claims 1 to 9. Its features are, The barrier layer (3) is made of ethylene-vinyl alcohol copolymer (EVOH), particularly a mixture of ethylene-vinyl alcohol copolymer (EVOH) and an elastic thermoplastic, preferably a thermoplastic elastomer (TPE). Among them, The ethylene-vinyl alcohol copolymer (EVOH) has an ethylene content of up to 30 mol%, preferably up to 27 mol%.

11. The multilayer tube (1) according to any one of claims 1 to 10. Its features are, The barrier layer (3) has a thickness of at least 0.1 mm (d3), especially at most 0.3 mm (d3), preferably at most 0.2 mm (d3), preferably between 0.1 mm and 0.2 mm, preferably 0.1 mm (d3).

12. The multilayer tube (1) according to any one of claims 1 to 11. Its features are, The inner layer (2) is made of the same material as the intermediate layer (4).

13. The multilayer tube (1) according to any one of claims 1 to 11. Its features are, The inner layer (2) is made of a conductive material, in particular, the inner layer (2) is made of a conductive doped and adhesively modified material, preferably, the inner layer (2) is made of a conductive doped and adhesively modified thermoplastic vulcanizate (TPV), and / or preferably, the inner layer (2) has carbon fiber, preferably carbon nanofiber, and / or carbon black.

14. The multilayer tube (1) according to any one of claims 1 to 13. Its features are, The inner layer (2) has a layer thickness (d2) of at least 0.2 mm, especially a layer thickness (d2) of up to 0.4 mm, preferably between 0.2 mm and 0.4 mm, and preferably 0.3 mm.

15. The multilayer tube (1) according to any one of claims 1 to 14. Its features are, The multilayer tube (1) has an outer diameter (9) between 19.7 mm and 21 mm, particularly 20.3 mm, and / or The multilayer tube (1) has an inner diameter (10) between 12.7 mm and 13 mm, and / or The multilayer tube (1) has a total layer thickness (d1) of at least 3.5 mm, especially a total layer thickness (d1) of up to 4 mm, preferably between 3.5 mm and 4 mm, preferably 3.8 mm, and / or The intermediate layer (4) has a layer thickness of at least 1 mm (d4), especially at most 3 mm (d4), preferably between 1 mm and 3 mm, preferably 2 mm (d4), and / or The outer layer (6) has a layer thickness (d6) of at least 0.5 mm, especially at most 1 mm, preferably between 0.5 mm and 1 mm, preferably 1 mm.

16. The application of a multilayer tube (1) according to any one of claims 1 to 15 in a medium-pressure system, particularly in a medium-pressure system for a fuel cell, preferably in a medium-pressure system for a hydrogen vehicle.

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