Pressure vessel for storing a gaseous medium under pressure and method for manufacturing a corresponding pressure vessel

Abstract

A pressure vessel (110) for storing a gaseous medium under pressure is proposed, wherein the pressure vessel (110) comprises a wall (111) and at least one metallic connection piece (112). The wall (111) encloses a cavity (114) for storing the gaseous medium, wherein the wall (111) includes an inner liner (116) made of plastic for sealing, and wherein the wall (111) comprises a reinforcing layer (118) arranged on the liner (116), preferably made of a fiber-reinforced plastic. The metallic connection piece (112) is connected to the wall (111) such that a media-tight connection is formed between a connection surface (120) of the metallic connection piece (112) and a connection surface (122) of the liner (116).Furthermore, a corresponding method for the manufacture of a pressure vessel (110), in particular a pressure vessel (110) for storing a gaseous medium under pressure, is specified.

Description

Technical field

[0001] The invention relates to a pressure vessel for storing a gaseous medium under pressure, wherein the pressure vessel comprises a wall and at least one metallic connection piece. The invention further relates to a method for manufacturing such a pressure vessel. The pressure vessel according to the invention can be used, for example, in gas-powered vehicles. However, other applications and areas of use for the pressure vessel are also conceivable in principle. Technical background

[0002] Pressure vessels of the type in question have been known in practice for years and exist in a wide variety of designs.

[0003] For example, gas-powered vehicles have a gas engine or a fuel cell with an electric motor as their drive system. To store sufficient fuel, the gas, or the gaseous medium, which can include hydrogen, is stored under high pressure in a tank or pressure vessel. Typical pressure vessels operate at pressures exceeding 200 bar, often reaching 600 bar, and sometimes even 700 or 800 bar. Therefore, the pressure vessel must not only be gas-tight at this pressure, but it must also exhibit high mechanical stability.

[0004] Pressure vessels for gas-powered vehicles are a known example from practical applications. These pressure vessels have a wall that includes an inner liner, for example made of thermoplastic, for sealing purposes, and a reinforcing layer made of fiber-reinforced plastic to provide mechanical stability. Preferably, the reinforcing layer can be wound and made of CFRP. CFRP is a carbon fiber-reinforced plastic.

[0005] The boss, as a metallic connection piece of the known pressure vessel, has a through-hole and a threaded connection. At least one of the two bosses of the pressure vessel is fitted with a tank fitting, which allows the pressure vessel to be filled or gas to be withdrawn in a controlled manner. The through-hole on the other boss is sealed with a closure, or another tank fitting or a safety valve is provided there.

[0006] Particular attention should be paid to the connection between the metallic fitting (the boss) and the liner in such pressure vessels, as a particularly tight seal is required here, even under mechanical stress, fluctuating internal pressure, or large temperature variations. This is a major challenge, especially for hydrogen tanks.

[0007] For example, DE 10 2014 009 343 A1 discloses a pressure vessel that exhibits the aforementioned characteristics. To improve its sealing properties, a clamping sleeve is provided between the reinforcement layer and the liner. This clamping sleeve is intended to transfer external loads acting via the boss to the reinforcement layer, thus protecting the liner from overloading that could lead to leakage.

[0008] DE 10 2010 021 667 A1 discloses a pressure vessel in which a sealing ring is provided between the boss and the liner to ensure tightness.

[0009] In DE 10 2016 219 638 A1 a pressure vessel is disclosed in which a sealing ring is pressed by a locking sleeve into a gap between boss and liner to achieve a seal between liner and boss.

[0010] However, conventional pressure vessels have the disadvantage of not being sufficiently resistant to fluctuating loads, whether due to temperature variations or changing pressures, and therefore do not guarantee a stable long-term seal. Furthermore, additional components are required to ensure a seal between the metallic connection and the liner. This is costly and complex, particularly due to the additional assembly steps.

[0011] Finally, the sealing concepts of known pressure vessels are inadequate and susceptible to problems with regard to the most complete possible emptying of the pressure vessels, since the tightness can be impaired, especially at lower filling pressures. Object of the invention

[0012] It would therefore be desirable to provide a pressure vessel for storing a gaseous medium under pressure that largely avoids the disadvantages of known pressure vessels. In particular, a design that is as stable and efficient as possible should be provided, with the tightness of the pressure vessel being improved as much as possible, preferably even when the pressure vessel is used at low filling pressures. Furthermore, a method for manufacturing such a pressure vessel should be described. General description of the invention

[0013] This problem is solved by a pressure vessel for storing a gaseous medium under pressure and by a method for manufacturing a pressure vessel with the features of the independent claims. Advantageous embodiments, which can be implemented individually or in any combination, are described in the dependent claims.

[0014] In a first aspect of the present invention, a pressure vessel for storing a gaseous medium under pressure is proposed, wherein the pressure vessel comprises a wall and at least one metallic connection piece, wherein the wall encloses a cavity for storing the gaseous medium, wherein the wall comprises an inner liner made of plastic for sealing, wherein the wall comprises a reinforcing layer arranged on the liner, preferably made of a fiber-reinforced plastic, and wherein the metallic connection piece is connected to the wall in such a way that a media-tight connection is formed between a connecting surface of the metallic connection piece and a connecting surface of the liner.

[0015] In accordance with the invention, it has first been recognized that, with regard to the most efficient design of the pressure vessel, it is particularly advantageous if the functional requirements placed on the pressure vessel can be realized with as few components as possible. The pressure vessel comprises a wall and at least one metallic connection piece, the wall enclosing a cavity for storing the gaseous medium. Furthermore, the wall comprises an inner plastic liner for sealing and a reinforcing layer arranged on the liner. The reinforcing layer can be made of a fiber-reinforced plastic.In a further manner according to the invention, it has been recognized that, with regard to improved tightness of the pressure vessel, it is particularly advantageous if a connection between the metallic connector and the liner can be created that is as direct and immediate as possible, especially an interlocking connection. According to the invention, the metallic connector is connected to the wall in such a way that a media-tight connection is formed between a connection surface of the metallic connector and a connection surface of the liner.

[0016] Consequently, a pressure vessel for storing a gaseous medium under pressure is specified, which provides the most stable and efficient design possible, with the tightness of the pressure vessel being improved as much as possible, especially at low filling pressures. Pressure vessels known from practice or from the prior art allow the pressure to be reduced to approximately 50 bar. A solution according to the invention can enable the pressure vessel to be almost completely emptied. The pressure vessel can be emptied to such an extent that only a few bar of overpressure are required. For example, in a pressure vessel according to an embodiment of the invention, the pressure vessel can be emptied down to an overpressure of 1 bar. A minimal residual pressure or overpressure is then no longer necessary for tightness reasons, but can instead serve to counteract contamination.

[0017] The term "gaseous medium," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without restriction, the term can refer in particular to a gas, for example, hydrogen.

[0018] The term "metallic fitting" or "boss," as used here, is a broad term and should be understood according to its usual and common meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a component of a pressure vessel that is at least partially made of metal and serves as a connection point for filling and emptying the liner with a gaseous medium. The metallic fitting can, for example, include a connection nozzle. Furthermore, the metallic fitting can serve as a connection point or interface between the liner and a filling valve. It can also serve as a connection point or interface between the liner and one or more downstream pressure components, such as pipes, control elements, and / or valves.

[0019] The term "liner," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a thermoplastic liner, preferably arranged internally within a pressure vessel, which can serve as a gas-tight reservoir. The liner can thus represent a storage space for a gaseous medium.

[0020] The term "connection surface of the metallic connector," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a portion of the surface of the metallic connector that comes into contact with the connection surface of the liner and forms a connection. This can be an outer contact layer of the metallic connector that comes into direct contact with the connection surface of the liner to form a connection, in particular a media-tight and preferably permanent, between the connector and the liner.

[0021] The term "liner connection surface," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a portion of the liner's surface that forms a connection with the connection surface of the metallic fitting. This can be an outer contact layer of the liner that comes into direct contact with the connection surface of the metallic fitting to form a connection, in particular a media-tight and preferably permanent, between the fitting and the liner.

[0022] The term "media-tight," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to the property of a connection to prevent media such as liquids or gases from escaping or penetrating. The media-tight connection between the metallic fitting and the liner can therefore be designed to be, in particular, gas-tight, that is, impermeable to gases, and thus prevent the unwanted ingress or egress of gaseous media from the liner.

[0023] Advantageously, the media-tight connection can be created through the direct interaction of the metallic connector and the liner. This efficiently establishes a direct connection between the metallic connector and the liner.

[0024] Advantageously, the media-tight connection between the metallic fitting and the liner can be either material-bonded or form-fit. This allows the metallic fitting and the liner to be effectively and permanently joined, thereby increasing both the strength of the connection and the sealing properties of the pressure vessel.

[0025] The media-tight connection between the metallic fitting and the liner can be achieved through a physical bond and / or a chemical bond. This allows for further improvement in the strength and stability of the connection as well as the sealing properties of the pressure vessel.

[0026] The term "physical connection," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a connection between the metallic connector and the liner that functions due to its mechanical design and construction. For example, a physical connection can be created by a positive fit. Thus, the metallic connector and the liner can be joined and anchored without the need for additional fasteners for the positive fit. The connection, with regard to the positive fit, can then be based solely on the shape and, where applicable, the fit, as well as, where applicable, the surface dimensions of the interacting components.

[0027] The term "chemical compound," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to connections between a metallic connector and a liner, which are based on strong (covalent) and / or weak (van der Waals) chemical bonds between the two components. Furthermore, a chemical compound between two components, such as the metallic connector and the liner, can be created by surface activation.

[0028] Advantageously, the contact surface of the metallic connector can be modified by surface activation. The term "surface activation," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to the process of modifying the surface energy (surface chemistry) of a material to enhance a specific property, such as hydrophobicity, reactivity, bonding, morphology, etc. Exemplary methods include plasma activation and surface chemical modification.The surface activation, which can be used in one embodiment of the invention, can in particular serve to improve the bonding properties of the connection surface of the liner and the connection surface of the metallic connector.

[0029] The contact surface of the metallic connector can be designed with a modified surface structure. This allows a surface structure to be created on the metallic connector that can interact with the contact surface of the liner to create a media-tight connection.

[0030] Advantageously, the modified surface structure can comprise a three-dimensionally structured surface with depressions. The term "depressions," as used here, is a broad term and should be understood to have its ordinary and common meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to an area that is sunken or recessed relative to the surrounding area. For example, it can refer to a recess in a surface, the area of ​​which is lower than its surroundings. Thus, the three-dimensionally structured surface can represent a surface with depressions and protrusions. For example, the depressions can be recesses in the connecting surface or in the outer contact layer of the metallic connector.

[0031] The depressions can have dimensions in the micrometer range. Therefore, it is conceivable that the depressions, in their horizontal extent (depression width) and / or in their vertical extent (depression height), could, for example, be in the range of 1 µm (= 0.001 mm) to 500 µm (= 0.5 mm), preferably in the range of 100 µm (= 0.1 mm) to 500 µm (= 0.5 mm).

[0032] Additionally or alternatively, the depressions can have dimensions in the nanometer range. Thus, it is conceivable that the depressions, in their horizontal extent (depression width) and / or their vertical extent (depression height), could, for example, range from 1 nm to 0.01 mm.

[0033] Particularly advantageous values ​​for the horizontal extent, i.e., for the depression width, and for the vertical extent, i.e., for the depression height, can preferably be chosen such that the relationship between depression width and depression height of the depressions is made dependent on the respective material properties of the materials to be joined, in particular metal and plastic.

[0034] Furthermore, the choice of suitable dimensions for the depressions, i.e., in terms of depression width and depth, can be determined by the method used to create the surface modification. Mechanical methods for creating the depressions are more suitable for depression dimensions in the range of 100 µm to 500 µm. Chemical methods for creating the depressions, on the other hand, are more suitable for depression dimensions in the range of 1 nm to 0.01 mm.

[0035] A superimposed structuring from fine to coarse can also be particularly advantageous and used in a targeted manner, whereby dimensions of the recesses can be provided in the micrometer range as well as in the nanometer range, for example according to the previously mentioned ranges.

[0036] Advantageously, the recesses of the three-dimensionally structured surface can have undercuts. The term "undercut," as used here, is a broad term and should be understood in its ordinary and common sense, as understood by those skilled in the art. The term is not limited to any special or adapted meaning. Without limitation, the term can refer in particular to a special type of recessed surface that is inaccessible with a straight tool. The undercut may be a special geometry or feature area on a first component that prevents a second component—received by the first component—from being easily removed from the first component, as it is blocked at one or more points during withdrawal.In turning, the term refers, for example, to a recess with a diameter that is generally located on the inner diameter of the part. In milling, it refers to a feature that is not visible from the spindle. In casting, it refers to a feature that cannot be formed with just a single die.

[0037] The recesses can have an inner surface with an undercut area, wherein the recesses are designed such that the proportion of the undercut area of ​​a recess in relation to the inner surface of the recess is in the range of 1% to 50%, preferably in the range of 20% to 50%, more preferably in the range of 30% to 50%, and particularly preferably in the range of 40% to 50%. This allows a sufficient undercut area to be created, which improves the strength of the connection and the sealing properties.

[0038] The term "internal surface," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to the area within a depression.

[0039] The term "undercut surface," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to the area within a recess formed by the undercuts in that recess.

[0040] Advantageously, the recesses can be shaped like a Christmas tree. This shape offers excellent connection strength and tightness when coupling the metallic connector and the liner.

[0041] Advantageously, a media-tight connection between the connection surface of the metallic fitting and the connection surface of the liner can be formed by recesses in the connection surface of the metallic fitting, particularly those with undercuts, and by plastic material on the connection surface of the liner facing the connection surface of the metallic fitting, wherein the plastic material sits in the recesses and completely or at least partially fills them. This further improves the strength and stability of the connection between the fitting and the liner, and consequently the sealing properties of the pressure vessel.

[0042] A variety of positive-locking connections can be formed between the interface surface of the metallic connector and the plastic material of the liner, particularly in the nanometer and / or micrometer range. This leads to a further improvement in the connection strength and the tightness of the pressure vessel.

[0043] Furthermore, a recess, particularly on the connection surface of the metallic connector, can have a recess width b1 and be spaced from an adjacent recess by a web width b2. Advantageously, the recess width b1 and the web width b2 can be configured such that the recess width b1 is larger than the web width b2. This leads to a further improvement in the connection strength and the tightness of the pressure vessel.

[0044] The term "deepness," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a, preferably maximum or minimum, horizontal extent of the recess, preferably at the connection surface of the metallic connector.

[0045] The term "web width," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a distance between two adjacent recesses, preferably on the connecting surface of the metallic connector.

[0046] Advantageously, the recess width b1 and the web width b2 can be designed depending on the strengths of the materials of the liner and the metallic connecting piece. This leads to a further improvement in the connection strength and the tightness of the pressure vessel.

[0047] The term "strength," as used here, is a broad term and should be understood in its ordinary and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, it can refer in particular to a property of a material that describes its ability to withstand external stresses or forces without failing or breaking. The strength of a material can be a critical factor in the selection of materials for a particular application, as it determines how safely and reliably the material can perform under stress. For example, the strength of a material can be characterized by its tensile strength. This value describes the maximum tensile force a material can withstand before it breaks. Tensile strength can be expressed in megapascals (MPa) or newtons per square millimeter (N / mm²). 2Strength can be measured. Other material properties that can describe strength include shear strength, fatigue strength, plasticity limit, and / or creep strength. The aforementioned properties can also be influenced by environmental conditions such as temperature, fluid wetting, and the like.

[0048] Furthermore, the liner material can have a first strength R1 and the metallic connecting piece material a second strength R2. Advantageously, the recess width b1 and the web width b2 can be designed such that the ratio b1 / b2 is essentially proportional to the ratio R2 / R1. In this way, the dimensions of the recesses and the surrounding surfaces are adapted to the material properties of the components to be joined, which improves the interlocking or connection of the plastic with the metal material. This leads to a further improvement in the pressure vessel's tightness.

[0049] The recesses can have a recess cross-sectional area B1 on the connecting surface of the metallic connector. Furthermore, the connecting surface of the metallic connector between the recesses can have a web cross-sectional area B2. Advantageously, the recess cross-sectional area B1 and the web cross-sectional area B2 can be configured such that the recess cross-sectional area B1 is larger than the web cross-sectional area B2. This leads to a further improvement in the connection strength and the tightness of the pressure vessel.

[0050] The term "recess cross-sectional area," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to the cross-sectional area of ​​all recesses on the connection surface of the metallic connector, preferably within a predetermined region of the connection surface.

[0051] The term "web cross-sectional area," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to the area on the connecting surface of the metallic connector between the recesses, preferably in a predetermined region of the connecting surface.

[0052] Preferably, the recess cross-sectional area B1 can refer to the cross-sectional area of ​​all recesses in a defined area on the connection surface of the metallic connector. The web cross-sectional area B2 can preferably refer to the remaining area in the defined area on the connection surface of the metallic connector between the recesses. Thus, it is conceivable that the advantageous ratios between the recess cross-sectional area B1 and the web cross-sectional area B2 are particularly useful where greater stresses can arise due to the geometric shape of the pressure vessel and the applied pressure. In less stressed areas, these advantageous ratios can be deviated from, for example, to enable more cost-effective and faster manufacturing.

[0053] Advantageously, the cross-sectional area of ​​the recess B1 and the cross-sectional area of ​​the web B2 can be designed depending on the strengths of the materials of the liner and the metallic connecting piece. This leads to a further improvement in the connection strength and the tightness of the pressure vessel.

[0054] Furthermore, the liner material can have a first strength R1 and the metallic connecting piece material a second strength R2. Advantageously, the recess cross-sectional area B1 and the web cross-sectional area B2 can be designed such that the ratio B1 / B2 is essentially proportional to the ratio R2 / R1. Thus, the dimensions of the recesses and their surrounding surfaces are adapted to the material properties of the components to be joined, which improves the interlocking or connection of the plastic with the metal material. This leads to a further improvement in the pressure vessel's tightness.

[0055] The recesses can have a depth h. Advantageously, the depth h of a recess can be configured such that, relative to the depth b1 of the recess, the depth h is 0.5 to 3 times the depth b1, preferably 1 to 2.5 times the depth b1, and particularly preferably 1.5 to 2 times the depth b1. This creates recesses, optionally with undercuts, which further improves the connection strength and the tightness of the pressure vessel.

[0056] The term "depression depth," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a, preferably maximum, vertical extent of a depression.

[0057] The recesses can have a depth h in the range of 0.001 mm to 0.5 mm, preferably in the range of 0.1 mm to 0.5 mm. In particular, recesses in the range of 0.1 mm to 0.5 mm can be advantageously produced by machining the surface of the metal connector. These recess dimensions make it possible to significantly increase the tensile strength in the edge regions of the connection between the connector and the liner.

[0058] Furthermore, the recesses can have a depth h ranging from 0.000001 mm to 0.01 mm. Recesses in this range can be particularly advantageously created by chemically treating the surface of the metallic connector. These dimensions make it possible to significantly increase the tightness and shear strength in the central area of ​​the connection between the connector and the liner.

[0059] Advantageously, recesses with varying depths can be created on the connection surface of the metallic fitting. For example, recesses with a depth ranging from 0.1 mm to 0.5 mm and those with a depth ranging from 0.000001 mm (= 1 nm) to 0.01 mm can be advantageously implemented. This further improves the strength and stability of the connection between the fitting and the liner, and consequently, the sealing properties of the pressure vessel.

[0060] A temperature control unit can be integrated into the metallic connector. This allows the unit to be used for rapid heating and / or cooling during processing or manufacturing of the pressure vessel. The temperature control unit can therefore be advantageously used to create the connection between the metallic connector and the liner.

[0061] The temperature control device can include at least one channel carrying a medium. For example, medium-carrying bores and / or feedthroughs are conceivable. During the manufacturing of the pressure vessel, media such as coolant and / or heat transfer fluids can be routed through this at least one channel to enable rapid heating and / or cooling.

[0062] Furthermore, the temperature control device may include at least one heating element to enable rapid heating and / or cooling.

[0063] Furthermore, the temperature control unit can include a ceramic separating layer. This ceramic separating layer can be integrated into the structure of the metallic connecting piece, enabling rapid heating and / or cooling times.

[0064] The pressure vessel can have a rotationally symmetrical, elongated shape, which is cylindrical in the middle area and closed at both ends with domed polar caps.

[0065] In a further aspect, a method for manufacturing a pressure vessel, in particular a pressure vessel for storing a gaseous medium under pressure, is proposed. The method comprises the following process steps. These can be carried out in the specified order. However, a different order is also possible, or a sequence in which two or more of the process steps are carried out simultaneously or overlapping in time is possible. Furthermore, one or more of the process steps can be repeated.

[0066] The process includes the following steps: a) Providing at least one metallic connector for the pressure vessel, wherein the metallic connector has a connecting surface for attachment to a connecting surface of a liner; b) Performing a surface modification on the connecting surface of the metallic connector to create a modified surface; c) Heating the metallic connector to a predetermined process temperature, in particular the plastic melting temperature; d) Producing or providing the plastic liner with a bonding surface, wherein the bonding surface of the liner is bonded to the bonding surface of the metallic connector in a media-tight manner.

[0067] The surface modification according to step b) can include laser processing, mechanical machining, chemical surface treatment, and / or surface activation. This allows the connection surface to be effectively modified to create a suitable surface, enabling the metallic fitting and the liner to be effectively and permanently bonded. Consequently, the strength of the connection between the fitting and the liner can be improved, ultimately enhancing the sealing properties of the pressure vessel.

[0068] Furthermore, the surface modification according to step b) can include applying a primer and / or an adhesive to the bonding surface of the metallic fitting. This can further improve the strength and stability of the connection between the fitting and the liner, and consequently the sealing properties of the pressure vessel.

[0069] Advantageously, the metallic connector for creating the liner, as well as its connection to the bonding surface of the metallic connector, can be placed in a mold and overmolded with plastic. This allows for the efficient production of the pressure vessel.

[0070] An exemplary procedure for producing a pressure vessel by overmolding can take the following aspects into account: - Creation of the surface structure on the metal piece and, if necessary, post-processing, for example with corona irradiation; - Inserting the, preferably preheated, metal piece into a plastic injection mold; - Heating, for example by means of delta heating, to the necessary process temperature of the metal piece; - Tool closure, which can be performed parallel to or even before the preceding step; as an alternative, the remaining tool cavity can be degassed after closure, for example by creating a vacuum, so that penetration into the surface structure of the metal piece is optimized; - Filling the remaining tool cavity with plastic; - Holding phase: During the injection phase and subsequent holding pressure, the plastic melt is pressed into the surface structure of the metal piece; - Cooling phase: For example, controlled at predetermined time intervals to minimize residual stresses as much as possible; - Tool opening; - Removal of the metal piece with the attached plastic component; - During the cooling phase: opening the tool, inserting the next piece of metal and then closing the tool, melting, mixing and uniforming the next plastic charge.

[0071] Advantageously, the liner's interface can be joined to the metallic connector's interface by thermoplastic welding, preferably by press-fitting. This allows for the efficient production of the pressure vessel.

[0072] An exemplary procedure for producing a pressure vessel using thermoplastic welding can take the following aspects into account: - Creation of the surface structure on the metal piece and, if necessary, post-processing, for example with corona irradiation); - If necessary, before treating the plastic surface, for example by corona irradiation, to remove surface contaminants; - Inserting the, preferably preheated, metal piece into a welding fixture, for example a holder, and inserting the pre-made plastic part into a preferably opposite fixture; - Heating the metal piece, for example by means of delta heating, to the necessary process temperature; - Pressing the plastic part with controlled force or speed up to a predetermined quota: During pressing, the molten plastic is forced into the surface structure of the metal piece; - Maintaining the position by means of force and / or position control; - Cooling phase, for example controlled at predetermined time intervals to minimize residual stresses as much as possible; - Device opening; - Removal of the metal piece with the attached plastic component.

[0073] Advantageously, the process for manufacturing a pressure vessel can include a controlled cooling process. During this cooling process, cooling can occur at predetermined time intervals. This reduces residual stresses in the parts being joined.

[0074] The following properties can be advantageously taken into account in order to achieve a suitable choice for the individual parameters within the process steps for the manufacturing process: - Strength of the metal; - Strength of the plastic; - Type of plastic-metal interface: physical and / or chemical; if chemical, then preferably with strong covalent or weak van der Waals bonds; - Viscosity of the plastic, preferably < 10 4Pa*s, at the processing temperature; the more fluid the plastic melt, the better the wetting and penetration and the greater the depression height h can be in relation to depression width b1 and web width b2; - Wettability of the metal by the polymer melt.

[0075] Embodiments of the invention can provide a direct connection between the connection surface of the metallic connector and the connection surface of the liner, thus creating a gas-tight or media-tight connection.

[0076] Embodiments of the invention can lead to cost reductions because fewer components, for example, no additional seal, are required, thus potentially reducing the number of assembly steps. Furthermore, improved prevention of gas or hydrogen permeation can be achieved, making the pressure vessel more competitive due to its enhanced energy efficiency and versatility.

[0077] Furthermore, eliminating the need for seal assembly reduces the risk of potential seal damage. Finally, the proposed connection method, according to one embodiment of the invention, allows for a leak-proof pressure vessel even at lower pressures, thus enabling broader utilization of the compressed gas inside, down to a lower limit pressure than usual. A limit pressure of approximately 50 bar is typically required.

[0078] In summary, without limiting further possible embodiments, the following embodiments are proposed: Embodiment 1: Pressure vessel for storing a gaseous medium under pressure, comprising a wall and at least one metallic connection piece, wherein the wall encloses a cavity for storing the gaseous medium, wherein the wall comprises an inner liner made of plastic for sealing, wherein the wall comprises a reinforcing layer arranged on the liner, preferably made of a fiber-reinforced plastic, and wherein the metallic connection piece is connected to the wall in such a way that a media-tight connection is formed between a connecting surface of the metallic connection piece and a connecting surface of the liner. Embodiment 2: Pressure vessel according to the preceding embodiment, wherein the media-tight connection is created by direct interaction of the metallic connector and the liner. Embodiment 3: Pressure vessel according to one of the preceding embodiments, wherein the media-tight connection between the metallic connecting piece and the liner is formed by material bonding and / or form-fitting. Embodiment 4: Pressure vessel according to one of the preceding embodiments, wherein the media-tight connection between the metallic connector and the liner is realized by a physical connection and / or by a chemical connection. Embodiment 5: Pressure vessel according to one of the preceding embodiments, wherein the connecting surface of the metallic connector is modified by surface activation. Embodiment 6: Pressure vessel according to one of the preceding embodiments, wherein the connecting surface of the metallic connector is formed with a modified surface structure. Embodiment 7: Pressure vessel of one of the preceding embodiments, wherein the modified surface structure comprises a three-dimensionally structured surface with depressions. Embodiment 8: Pressure vessel according to one of the preceding embodiments, wherein the recesses have dimensions in the micrometer range. Embodiment 9: Pressure vessel according to one of the preceding embodiments, wherein the recesses have dimensions in the nanometer range. Embodiment 10: Pressure vessel according to one of the preceding embodiments, wherein the recesses of the three-dimensionally structured surface have undercuts. Embodiment 11: Pressure vessel according to one of the preceding embodiments, wherein the recesses have an inner surface with an undercut surface, wherein the recesses are designed such that the proportion of the undercut surface of a recess in relation to the inner surface of the recess is in the range of 1% to 50%, preferably in the range of 20% to 50%, more preferably in the range of 30% to 50%, and particularly preferably in the range of 40% to 50%. Embodiment 12: Pressure vessel according to one of the preceding embodiments, wherein the depressions are shaped like a Christmas tree. Embodiment 13: Pressure vessel according to one of the preceding embodiments, wherein the media-tight connection between the connection surface of the metallic connector and the connection surface of the liner is formed by recesses in the connection surface of the metallic connector, in particular having undercuts, and by plastic material of the connection surface of the liner facing the connection surface of the metallic connector, wherein the plastic material sits in the recesses and fills them completely or at least partially. Embodiment 14: Pressure vessel according to one of the preceding claims, wherein a plurality of positive locking connections are formed between the connecting surface of the metallic connecting piece and the plastic material of the liner, particularly in the nano and / or micrometer range. Embodiment 15: Pressure vessel according to one of the preceding embodiments, wherein a recess, preferably on the connecting surface of the metallic connecting piece, has a recess width b1 and is spaced apart from an adjacent recess by a web width b2, wherein the recess width b1 and the web width b2 are designed such that the recess width b1 is larger than the web width b2. Embodiment 16: Pressure vessel of one of the preceding embodiments, wherein the recess width b1 and the web width b2 are designed depending on the strengths of the materials of the liner and the metallic connecting piece. Embodiment 17: Pressure vessel according to one of the preceding embodiments, wherein the material of the liner has a first strength R1 and the material of the metallic connecting piece has a second strength R2, wherein the recess width b1 and the web width b2 are designed such that a ratio b1 / b2 is substantially proportional to a ratio R2 / R1. Embodiment 18: Pressure vessel according to one of the preceding embodiments, wherein the recesses on the connecting surface of the metallic connector have a recess cross-sectional area B1, wherein the connecting surface of the metallic connector between the recesses has a web cross-sectional area B2, wherein the recess cross-sectional area B1 and the web cross-sectional area B2 are designed such that the recess cross-sectional area B1 is larger than the web cross-sectional area B2. Embodiment 19: Pressure vessel according to one of the preceding embodiments, wherein the recess cross-sectional area B1 and the web cross-sectional area B2 are designed depending on the strengths of the materials of the liner and the metallic connecting piece. Embodiment 20: Pressure vessel according to one of the preceding embodiments, wherein the material of the liner has a first strength R1 and the material of the metallic connecting piece has a second strength R2, wherein the recess cross-sectional area B1 and the web cross-sectional area B2 are designed such that a ratio B1 / B2 is substantially proportional to a ratio R2 / R1. Embodiment 21: Pressure vessel according to one of the preceding embodiments, wherein the recesses have a recess height h, wherein the recess height h of a recess is designed such that the recess height h is 0.5 to 3 times the recess width b1, preferably 1 to 2.5 times the recess width b1, particularly preferably 1.5 to 2 times the recess width b1. Embodiment 22: Pressure vessel according to one of the preceding embodiments, wherein the recesses have a recess height h in the range of 0.001mm to 0.5mm, preferably in the range of 0.1mm to 0.5mm. Embodiment 23: Pressure vessel according to one of the preceding embodiments, wherein a temperature control device is integrated into the metallic connecting piece. Embodiment 24: Pressure vessel according to one of the preceding embodiments, wherein the temperature control device serves to create the connection between the metallic connector and the liner. Embodiment 25: Pressure vessel according to one of the preceding embodiments, wherein the temperature control device comprises at least one media-carrying channel, at least one heating element and / or at least one ceramic separating layer. Embodiment 26: Pressure vessel according to one of the preceding embodiments, wherein the pressure vessel has a rotationally symmetrical, elongated shape, which is cylindrical in the central region and is closed at both ends with domed polar caps. Embodiment 27: Method for manufacturing a pressure vessel, in particular a pressure vessel for storing a gaseous medium under pressure, preferably a pressure vessel according to one of the preceding embodiments, comprising the following steps: a) Providing at least one metallic connector for the pressure vessel, wherein the metallic connector has a connecting surface for attachment to a connecting surface of a liner; b) Performing a surface modification on the connecting surface of the metallic connector to create a modified surface; c) Heating the metallic connector to a predetermined process temperature, in particular the plastic melting temperature; d) Producing or providing the plastic liner with a bonding surface, wherein the bonding surface of the liner is bonded to the bonding surface of the metallic connector in a media-tight manner. Embodiment 28: Method according to one of the preceding embodiments, wherein the surface modification according to step b) comprises laser processing, mechanical processing, chemical surface treatment and / or surface activation. Embodiment 29: Method according to one of the preceding embodiments, wherein the surface modification according to step b) comprises applying a primer and / or an adhesive to the joining surface of the metallic connector. Embodiment 30: Method according to one of the preceding embodiments, wherein the metallic connector for producing the liner and its connection to the joining surface of the metallic connector is placed in a mold and overmolded with plastic. Embodiment 31: Method according to one of the preceding embodiments, wherein the connecting surface of the liner is joined to the connecting surface of the metallic connector by thermoplastic welding, preferably by compression welding. Embodiment 32: Method according to one of the preceding embodiments, comprising: e) Performing a controlled cooling process Brief description of the characters

[0079] Further details and features will become apparent from the following description of exemplary embodiments, particularly in conjunction with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. Identical reference numerals in the individual figures denote identical or functionally equivalent elements, or elements that correspond to one another with respect to their functions.

[0080] Specifically, we show: Fig. 1 in a schematic representation a pressure vessel according to an embodiment of the invention; Fig. 2 in a schematic representation a pressure vessel according to a further embodiment of the invention; Fig. 3 in a schematic representation an enlarged cross-sectional view of a pressure vessel according to a further embodiment of the invention; Fig. 4a and Fig. 4b in a schematic representation an enlarged cross-sectional view of a pressure vessel according to a further embodiment of the invention; Fig. 5 in a schematic representation an enlarged cross-sectional view of a pressure vessel according to a further embodiment of the invention; Fig. 6 in a schematic representation an enlarged cross-sectional view of a pressure vessel according to a further embodiment of the invention; Fig. 7 in a schematic view an illustration of a method for manufacturing a pressure vessel according to an embodiment of the invention; and Fig. Figure 8 shows a schematic illustration of a method for manufacturing a pressure vessel according to a further embodiment of the invention. Description of the exemplary implementations

[0081] Fig. Figure 1 shows a schematic representation of a pressure vessel 110 according to an embodiment of the invention. The pressure vessel 110 serves to store a gaseous medium under pressure. The pressure vessel 110 comprises a wall 111 and at least one metallic connection piece 112. The wall encloses a cavity 114 for storing the gaseous medium. Furthermore, the wall includes an inner liner 116 made of plastic for sealing and a reinforcing layer 118 arranged on the liner 116. The reinforcing layer 118 can be made of a fiber-reinforced plastic. The metallic connection piece 112 is connected to the wall such that a media-tight connection is formed between a connecting surface 120 of the metallic connection piece 112 and a connecting surface 122 of the liner 116.

[0082] The media-tight connection is created by the direct interaction of the metallic connector 112 and the liner 116. This media-tight connection can be formed by material bonding and / or form-fitting. Thus, the metallic connector 112 and the liner 116 are effectively and permanently joined at their connection surfaces 120 and 122, thereby increasing both the strength of the connection and the sealing properties of the pressure vessel 110.

[0083] Fig. Figure 2 shows a schematic representation of a pressure vessel 110 according to a further embodiment of the invention. The pressure vessel 110 serves to store a gaseous medium under pressure. The pressure vessel 110 comprises a wall and at least one metallic connection piece 112. The wall encloses a cavity 114 for storing the gaseous medium. Furthermore, the wall includes an inner liner 116 made of plastic for sealing and a reinforcing layer 118 arranged on the liner 116. The reinforcing layer 118 can be made of a fiber-reinforced plastic. The metallic connection piece 112 is connected to the wall such that a media-tight connection is formed between a connecting surface 120 of the metallic connection piece 112 and a connecting surface 122 of the liner 116.

[0084] The media-tight connection between the metallic connector 112 and the liner 116 is achieved through a physical connection. For this purpose, the connection surface 120 of the metallic connector 112 is formed with a modified surface structure, wherein the modified surface structure comprises a three-dimensionally structured surface with recesses 124. The recesses 124 of the three-dimensionally structured surface have undercuts 126.

[0085] The media-tight connection between the connection surface 120 of the metallic connector 112 and the connection surface 122 of the liner 116 is thus formed by the recesses 124, which have undercuts 126, and by the plastic material of the connection surface 122 of the liner 116 facing the connection surface 120 of the metallic connector 112. The plastic material of the liner 116 sits in the recesses 124 of the metallic connector 112 and fills them completely or at least partially. This further improves the strength and stability of the connection between the metallic connector 112 and the liner 116, and consequently the sealing properties of the pressure vessel 110.

[0086] Fig. Figure 3 shows a schematically enlarged cross-sectional view of a pressure vessel 110 according to a further embodiment of the invention. The pressure vessel 110 comprises a media-tight connection, which is created by the direct interaction of the metallic connecting piece 112 and the liner 116.

[0087] The media-tight connection between the metallic connector 112 and the liner 116 is achieved through a physical connection, specifically a positive fit. This further improves the strength and stability of the connection as well as the sealing properties of the pressure vessel 110.

[0088] For this purpose, the connecting surface 120 of the metallic connector 112 is designed with a modified surface structure. This allows a surface structure to be created on the metallic connector 112 that can interact with the connecting surface 122 of the liner 116 to create the media-tight connection. The modified surface structure comprises a three-dimensionally structured surface with depressions 124. The depressions 124 are areas that are sunken or recessed relative to the surrounding area, namely the remaining connecting surface 120 of the metallic connector 112, in the form of recesses on the connecting surface 120 of the metallic connector 112. Thus, the three-dimensionally structured surface represents a surface with depressions 124 and protrusions 125.

[0089] The recesses 124 can have dimensions in the micrometer range. Thus, it is conceivable that the recesses 124, in their horizontal extent (recess width b1) and / or in their vertical extent (recess height h), can, for example, be in the range of 1 µm to 500 µm (= 0.5 mm), preferably in the range of 100 µm to 500 µm.

[0090] Additionally or alternatively, the recesses 124 can have dimensions in the nanometer range. Thus, it is conceivable that the recesses 124, in their horizontal extent (recess width b1) and / or in their vertical extent (recess height h), could, for example, range from 1 nm to 0.01 mm.

[0091] The media-tight connection between the connection surface 120 of the metallic connector 112 and the connection surface 122 of the liner 116 is formed by the recesses 124, which have undercuts 126, and by the plastic material of the connection surface 122 of the liner 116 facing the connection surface 120 of the metallic connector 112. The plastic material sits in the recesses 124 and completely or at least partially fills them. This further improves the strength and stability of the connection between the connector and the liner, and consequently the sealing properties of the pressure vessel 110.

[0092] Between the connecting surface 120 of the metallic connector 112 and the plastic material of the liner 116, a large number of such positive locking connections are formed, especially in the nano and / or micrometer range.

[0093] In particular, the connecting surface 122 of the liner 116 engages in the recesses 124 in such a way that the connection of the liner 116 cannot be removed or detached from the metal body or the metallic connector 112 without causing damage. This creates a permanent connection between the metallic connector 112 and the plastic liner 116.

[0094] Thus, the media-tight connection between the metallic connector 112 and the plastic liner 116 is established by a physical connection. In any case, the recesses 124 are designed in a specific shape, as will be explained in more detail below, to allow the pressure vessel 110 to be used even at low filling pressures without impairing its tightness, thereby expanding its range of applications.

[0095] A recess 124 has a recess width b1 on the connecting surface 120 of the metallic connector 112 and is spaced from an adjacent recess 124 by a web width b2. The recess width b1 and the web width b2 are designed such that the recess width b1 is larger than the web width b2. This leads to a further improvement in the connection strength and the tightness of the pressure vessel 110.

[0096] The recess width b1 and the web width b2 are further designed depending on the strengths of the materials of the liner 116 and the metallic connecting piece 112.

[0097] The material of the liner 116 has a first strength R1, and the material of the metallic connecting piece 112 has a second strength R2. Advantageously, the recess width b1 and the web width b2 can now be designed such that a ratio b1 / b2 is essentially proportional to a ratio R2 / R1. Thus, the dimensions of the recesses 124 and the surrounding surfaces are adapted to the material properties of the components to be joined, which improves the interlocking or connection of the plastic with the metal material. This leads to a further improvement in the tightness of the pressure vessel 110.

[0098] For example, the metallic connector 112 can be made of steel 42CrMo4 with a first strength R1 of about 900MPa and the liner 116 of PA66 with a second strength R2 determined at 90 °C of about 30MPa, resulting in a ratio R1 / R2 of 900MPa / 30MPa = 30.

[0099] Another example: The metallic connector 112 can be made of aluminium 1070 with a first strength R1 of about 100 MPa determined at 90 °C and the liner 116 of PA66 with a second strength R2 of about 30 MPa determined at 90 °C, resulting in a ratio R1 / R2 of 100MPa / 30MPa = 3.33.

[0100] Furthermore, for example, the metallic connector 112 can be made of aluminium 1070 with a first strength R1 of approximately 100MPa determined at 90 °C and the liner 116 can be made of PA66GF30 with a second strength R2 of approximately 100MPa determined at 90 °C, resulting in a ratio R1 / R2 of 100MPa / 100MPa = 1.

[0101] Consequently, the three previously mentioned examples combined result in the following area ratios: - R(steel 42CrMo4 conditioned to Pa66 90°C) = 30 - R(Al 1070 at 90°C) to R (Pa66 conditioned at 90°C) = 3.33 - R(Al 1070 at 90°C) to R (Pa66GF30 conditioned at 90°C) = 1

[0102] Fig. 4a and Fig. Figure 4b shows a schematically enlarged cross-sectional view of a pressure vessel 110 according to a further embodiment of the invention. The pressure vessel 110 comprises a media-tight connection, which is created by the direct interaction of the metallic connector 112 and the liner 116.

[0103] The recesses 124 can have a recess cross-sectional area B1 on the connecting surface 120 of the metallic connector 112. Furthermore, the connecting surface 120 of the metallic connector 112 can have a web cross-sectional area B2 between the recesses 124.

[0104] The recess cross-sectional area B1 and the web cross-sectional area B2 can be designed such that the recess cross-sectional area B1 is larger than the web cross-sectional area B2. This leads to a further improvement in the connection strength and the tightness of the pressure vessel 110. Fig. 4a the depression cross-sectional area B1 and the web cross-sectional area B2 are only schematically indicated and are not intended to illustrate a concrete relationship.

[0105] The recess cross-sectional area B1 refers in particular to the cross-sectional area of ​​all recesses 124 on the connecting surface of the metallic connecting piece 112.

[0106] The cross-sectional area of ​​the web B2 refers to the area on the connecting surface of the metallic connecting piece 112 between the recesses 124.

[0107] Preferably, the recess cross-sectional area B1 can refer to the cross-sectional area of ​​all recesses 124 in a predetermined area on the connection surface of the metallic connector 112. The web cross-sectional area B2 can preferably refer to the area in the predetermined area on the connection surface of the metallic connector 112 between the recesses 124. It is conceivable that the advantageous conditions, for example, between the recess cross-sectional area B1 and the web cross-sectional area B2, are particularly useful where greater stresses can arise due to the geometric shape of the pressure vessel and the acting pressure. In less stressed areas, these advantageous conditions can be deviated from, for example, to enable more cost-effective and faster manufacturing.

[0108] Depending on the design of the recesses 124, different recess cross-sectional areas B1 and web cross-sectional areas B2 can result. The schematic representation according to Fig. 4a (see Fig. 4a, above) shows corresponding surfaces B1 and B2, which result from the creation of hole-like depressions 124 in the connecting surface 120 of the metallic connecting piece 112.

[0109] The schematic representation according to Fig. 4b (see Fig. 4b, above) shows surfaces B1 and B2, which result from the creation of parallel, essentially groove-shaped, depressions 124 in the connecting surface 120 of the metallic connecting piece 112.

[0110] The recesses 124 according to the Fig. 4a and Fig. 4b have a recess width b1 on the connecting surface 120 of the metallic connecting piece 112 and are spaced apart from an adjacent recess 124 by a web width b2.

[0111] The recesses 124 can further have a recess height h. Advantageously, the recess height h of a recess 124 can be configured such that the recess height h is 0.5 to 3 times the recess width b1, preferably 1 to 2.5 times the recess width b1, and particularly preferably 1.5 to 2 times the recess width b1. Thus, recesses 124, optionally with undercuts 126, are realized, which allows for a further improvement in the connection strength and the tightness of the pressure vessel 110.

[0112] The cross-sectional area of ​​the recess B1 and the cross-sectional area of ​​the web B2 can be designed according to the strengths of the materials of the liner 116 and the metallic connector 112. Furthermore, the material of the liner 116 can have a first strength R1 and the material of the metallic connector 112 a second strength R2. Advantageously, the cross-sectional area of ​​the recess B1 and the cross-sectional area of ​​the web B2 can then be designed such that the ratio B1 / B2 is essentially proportional to the ratio R2 / R1. Thus, the dimensions of the recesses 124 and the surrounding surfaces are adapted to the material properties of the components to be joined, which improves the interlocking or connection of the plastic with the metal material. This leads to a further improvement in the tightness of the pressure vessel 110.

[0113] The connection surface of the metallic connector 112 is formed with a modified surface structure. This creates a surface structure on the metallic connector 112 that interacts with the connection surface of the liner 116 to create a media-tight connection.

[0114] The modified surface structure thus comprises a three-dimensionally structured surface with depressions 124. The depression 124 corresponds to a recess on the connecting surface of the metallic connector 112, wherein the area of ​​the recess is lower than its surroundings. Therefore, the three-dimensionally structured surface can represent a surface with depressions 124 and raised areas.

[0115] The recesses 124 can have dimensions in the micrometer range. Thus, it is conceivable that the recesses 124 can have dimensions in both their horizontal extent, i.e., recess width, and their vertical extent, i.e., recess height, for example, in the range of 1 µm (= 0.001 mm) to 500 µm (= 0.5 mm), preferably in the range of 100 µm to 500 µm.

[0116] Additionally or alternatively, the recesses 124 can have dimensions in the nanometer range. Thus, it is conceivable that the recesses 124 could have dimensions ranging, for example, from 1 nm to 0.01 mm in both their horizontal extent (i.e., recess width) and their vertical extent (i.e., recess height).

[0117] The recesses 124 of the three-dimensionally structured surface have undercuts 126. The recesses 124 have an inner surface with an undercut area. Advantageously, the recesses 124 are designed such that the proportion of the undercut area of ​​a recess 124 relative to the inner surface of the recess 124 is in the range of 1% to 50%, preferably in the range of 20% to 50%, more preferably in the range of 30% to 50%, and particularly preferably in the range of 40% to 50%. This allows a sufficient undercut area to be created, which improves the strength of the connection and the sealing properties.

[0118] The inner surface is the area within the recess. The undercut surface is a sub-area of ​​the inner surface, referring in particular to the area within a recess 124 formed by the undercuts 126 in the recess 124.

[0119] Fig. Figure 5 shows a schematic representation of an enlarged cross-sectional view of a pressure vessel 110 according to a further embodiment of the invention.

[0120] The connection surface of the metallic connector 112 is formed with a modified surface structure. This creates a surface structure on the metallic connector 112 that interacts with the connection surface of the liner 116 to create a media-tight connection.

[0121] The modified surface structure thus comprises a three-dimensionally structured surface with depressions 124. The depression 124 corresponds to a recess on the connecting surface of the metallic connector 112, wherein the area of ​​the recess is lower than its surroundings. Therefore, the three-dimensionally structured surface can represent a surface with depressions 124 and raised areas.

[0122] The recesses 124 can have dimensions in the micrometer range. Thus, it is conceivable that the recesses 124, in their horizontal extent (i.e., recess width) and / or in their vertical extent (i.e., recess height), can be in the range of, for example, 1 µm to 500 µm (= 0.5 mm), preferably in the range of 100 µm to 500 µm.

[0123] Additionally or alternatively, the recesses 124 can have dimensions in the nanometer range. Thus, it is conceivable that the recesses 124, in their horizontal extent (i.e., recess width) and / or in their vertical extent (i.e., recess height), could, for example, range from 1 nm to 0.01 mm.

[0124] The recesses 124 of the three-dimensionally structured surface have undercuts 126. The recesses 124 have a recess height h. Advantageously, the recess height h of a recess 124 can be configured such that the recess height h is 0.5 to 3 times the recess width b1, preferably 1 to 2.5 times the recess width b1, and particularly preferably 1.5 to 2 times the recess width b1. Thus, recesses 124, preferably with undercuts 126, are realized, which further improves the connection strength and the tightness of the pressure vessel 110.

[0125] The recesses 124 can have a recess height h in the range of 0.001 mm to 0.5 mm, preferably in the range of 0.1 mm to 0.5 mm. In particular, the recesses 124 with a recess height in the range of 0.1 mm to 0.5 mm can be advantageously produced by machining the connection surface of the metallic connector 112. These dimensions of the recesses 124 make it possible to significantly increase the tensile strength in the edge regions of the connection between the connector 112 and the liner 116.

[0126] Furthermore, the recesses 124 can have a recess height h in the range of 0.000001 mm (= 1 nm) to 0.01 mm. Recesses 124 in this range can be particularly advantageously produced by a chemical treatment of the connection surface of the metallic connector 112. These dimensions make it possible to significantly increase the tightness and shear strength in the central area of ​​the connection between connector 112 and liner 116.

[0127] Advantageously, recesses 124 with different depths can be realized on the connection surface of the metallic connector 112. For example, recesses 124 with a depth in the range of 0.1 mm to 0.5 mm and recesses 124 with a depth in the range of 0.000001 mm to 0.01 mm can be realized particularly advantageously. This further improves the strength and stability of the connection between the connector 112 and the liner 116, and consequently the sealing properties of the pressure vessel 110.

[0128] Fig. Figure 6 shows a schematic representation of an enlarged cross-sectional view of a pressure vessel 110 according to a further embodiment of the invention. In the following, only the differences from the one described in the Fig. The embodiments shown in 3 to 5 are described, and identical design elements and features are identified by the same reference numerals. In the embodiment shown in Fig. In the embodiment shown in section 6, the recesses 124 are essentially shaped like a Christmas tree. It is expressly pointed out that the recesses in the Fig. The embodiments shown in Figures 3 to 5 can be modified so that the recesses 124 are essentially shaped like a Christmas tree. This shape provides excellent connection strength and tightness when coupling the metallic connector 112 and the liner 116.

[0129] Fig. Figure 7 shows a schematic illustration of a method 210 for manufacturing a pressure vessel 110 according to an embodiment of the invention.

[0130] The process 210 for manufacturing a pressure vessel 110, in particular a pressure vessel 110 for storing a gaseous medium under pressure, comprises the following steps: - (Reference numeral 212) Providing at least one metallic connector 112 for the pressure vessel 110, wherein the metallic connector 112 has a connecting surface for attachment to a connecting surface of a liner 116; - (Reference numeral 214) Performing a surface modification on the connecting surface of the metallic connector 112 to produce a modified surface; - (Reference numeral 216) Heating the metallic connector 112 to a predetermined process temperature, in particular the plastic melting temperature; - (Reference numeral 218) Producing the liner 116 from plastic with a bonding surface, wherein the bonding surface of the liner 116 is connected to the bonding surface of the metallic connector 112 in a media-tight manner.

[0131] Fig. Figure 8 shows a schematic illustration of a method 200 for manufacturing a pressure vessel 110 according to a further embodiment of the invention.

[0132] The process 210' for manufacturing a pressure vessel 110, in particular a pressure vessel 110 for storing a gaseous medium under pressure, comprises the following steps: - (Reference numeral 212) Providing at least one metallic connector 112 for the pressure vessel 110, wherein the metallic connector 112 has a connecting surface for attachment to a connecting surface of a liner 116; - (Reference numeral 214) Performing a surface modification on the connecting surface of the metallic connector 112 to produce a modified surface; - (Reference numeral 216) Heating the metallic connector 112 to a predetermined process temperature, in particular the plastic melting temperature; - (reference 218') Providing the plastic liner 116 with a bonding surface, wherein the bonding surface of the liner 116 is connected to the bonding surface of the metallic connector 112 in a media-tight manner.

[0133] Regarding further advantageous embodiments of the pressure vessel according to the invention and the method according to the invention for manufacturing a pressure vessel, reference is made to the general part of the description and to the attached claims to avoid repetition.

[0134] Finally, it should be expressly pointed out that the exemplary embodiments of the pressure vessel and the method for manufacturing a pressure vessel described above serve only to discuss the claimed teaching, but do not limit it to the exemplary embodiments. Reference symbol list 110 pressure vessels 111 Wall 112 Metallic connector 114 Cavity 116 liners 118 Reinforcing layer 120 Connection surface of the metallic connector 122 Liner connection surface 124 depressions 125 surveys 126 undercuts 210 Manufacturing processes 210' Manufacturing process 212 Procedure step 214 Procedure step 216 Procedure step 218 Procedure step 218' Procedure step b1 Depth of focus b2 rib width B1 depression cross-sectional area B2 web cross-sectional area h Depth of depression QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 009 343 A1

[0007] DE 10 2010 021 667 A1

[0008] DE 10 2016 219 638 A1

[0009]

Claims

[1] Pressure vessel (110) for storing a gaseous medium under pressure, with a wall (111) and at least one metallic connecting piece (112), wherein the wall (111) encloses a cavity (114) for storing the gaseous medium, wherein the wall (111) comprises an internal liner (116) made of plastic for sealing, wherein the wall (111) comprises a reinforcing layer (118) arranged on the liner (116), preferably made of a fiber-reinforced plastic, and wherein the metallic connecting piece (112) is connected to the wall (111) in such a way that a media-tight connection is formed between a connecting surface (120) of the metallic connecting piece (112) and a connecting surface (122) of the liner (116). [2] Pressure vessel (110) according to the preceding claim, wherein the media-tight connection is produced by direct interaction of the metallic connecting piece (112) and the liner (116). [3] Pressure vessel (110) according to one of the preceding claims, wherein the media-tight connection between the metallic connecting piece (112) and the liner (116) is formed in a material-locking and / or form-locking manner, and / or wherein the media-tight connection between the metallic connecting piece (112) and the liner (116) is realized by a physical connection and / or by a chemical connection. [4] Pressure vessel (110) according to one of the preceding claims, wherein the connecting surface (120) of the metallic connecting piece (112) is formed with a modified surface structure, wherein the modified surface structure comprises a three-dimensionally structured surface with depressions (124), and wherein the depressions (124) can have dimensions in the nanometer and / or micrometer range. [5] Pressure vessel (110) according to one of the preceding claims, wherein the recesses (124) of the three-dimensionally structured surface have undercuts (126). [6] Pressure vessel (110) according to one of the preceding claims, wherein the recesses (124) have an inner surface with an undercut surface, wherein the recesses (124) are formed such that the proportion of the undercut surface of a recess (124) in relation to the inner surface of the recess (124) is in the range of 1% to 50%, preferably in the range of 20% to 50%, more preferably in the range of 30% to 50%, and particularly preferably in the range of 40% to 50%. [7] Pressure vessel (110) according to one of the preceding claims, wherein the recesses (124) are fir-tree shaped. [8] Pressure vessel (110) according to one of the preceding claims, wherein the media-tight connection between the connecting surface (120) of the metallic connecting piece (112) and the connecting surface (122) of the liner (116) is formed by recesses (124), in particular having undercuts (126), in the connecting surface (120) of the metallic connecting piece (112) and by plastic material of the connecting surface (122) of the liner (116) facing the connecting surface of the metallic connecting piece (112), wherein the plastic material sits in the recesses (124) and fills them completely or at least partially. [9] Pressure vessel (110) according to one of the preceding claims, wherein a depression (124) has a depression width b1 and is spaced from an adjacent depression (124) by a web width b2, wherein the depression width b1 and the web width b2 are formed such that the depression width b1 is greater than the web width b2. [10] Pressure vessel (110) according to one of the preceding claims, wherein the recess width b1 and the web width b2 are formed depending on the strengths of the materials of the liner (116) and the metallic connecting piece (112). [11] Pressure vessel (110) according to one of the preceding claims, wherein the material of the liner (116) has a first strength R1 and the material of the metallic connecting piece (112) has a second strength R2, wherein the recess width b1 and the web width b2 are formed such that a ratio b1 / b2 is substantially proportional to a ratio R2 / R1. [12] Pressure vessel (110) according to one of the preceding claims, wherein the recesses (124) on the connecting surface (120) of the metallic connecting piece (112) have a recess cross-sectional area B1, wherein the connecting surface (120) of the metallic connecting piece (112) between the recesses (124) has a web cross-sectional area B2, wherein the recess cross-sectional area B1 and the web cross-sectional area B2 are formed such that the recess cross-sectional area B1 is larger than the web cross-sectional area B2. [13] Method for producing a pressure vessel (110), in particular a pressure vessel (110) for storing a gaseous medium under pressure, preferably a pressure vessel (110) according to one of the preceding claims, comprising the following steps: a) providing at least one metallic connecting piece (112) for the pressure vessel (110), wherein the metallic connecting piece (112) has a connecting surface (120) for connection to a connecting surface (122) of a liner (116); b) performing a surface modification on the connecting surface (120) of the metallic connecting piece (112) to produce a modified surface; c) heating the metallic connecting piece (112) to a predetermined process temperature, in particular plastic melting temperature; d) producing or providing the liner (116) from plastic with a connecting surface (122), wherein the connecting surface (122) of the liner (116) is connected to the connecting surface (120) of the metallic connecting piece (112) in a media-tight manner. [14] Method according to one of the preceding claims, wherein the surface modification according to step b) comprises laser processing, mechanical processing, chemical surface treatment, surface activation, applying a primer to the connecting surface (120) of the metallic connecting piece (112) and / or applying an adhesive to the connecting surface (120) of the metallic connecting piece (112). [15] Method according to one of the preceding claims, wherein the metallic connecting piece (112) is introduced into a mold and overmolded with plastic for producing the liner (116) and its connection to the connecting surface (120) of the metallic connecting piece (112), or wherein the connecting surface (122) of the liner (116) is connected, preferably pressed, to the connecting surface (120) of the metallic connecting piece (112) by thermoplastic welding.

Images