Pressurized gas container

Abstract

A pressurized gas container (1) with a storage volume surrounded by an inner shell (2) made of plastic material and at least one outer shell (3) made of fiber-reinforced plastic, with at least one end section (4) attached to one end of the storage volume, wherein a connecting sleeve (6) is arranged in a bore (5) of the end section (4), wherein the material of the inner shell (2) is directly or via a suitable intermediate layer (9) is metallurgically bonded to the material of the connecting sleeve (6), and the inner shell (2) is connected to the end face of the connecting sleeve (6) facing the interior of the storage volume.

Description

[0001] The invention relates to a pressurized gas container according to the preamble of claim 1. Furthermore, the invention relates to the use of a pressurized gas container according to the invention as per claim 9.

[0002] Compressed gas containers, especially so-called type IV compressed gas containers, are known from the general state of the art. They can be used, for example, in vehicles for storing hydrogen at high pressures. Nominal pressures of 700 bar are now common, particularly for hydrogen. Higher pressures are also conceivable. For compressed natural gas, for which such compressed gas containers are also very frequently used, nominal pressures in the range of 260 bar are typical.

[0003] The construction of such a type IV pressure vessel is known from the prior art. The pressure vessel consists of at least two layers: an inner liner and an outer liner. The inner liner is typically made of a material that is very dense for the gas being stored under high pressure, for example, a single- or multi-layered plastic sheet, optionally with a metallic interlayer or foil. The sole purpose of the inner liner is to seal the pressure vessel as effectively as possible against gas escape. The high pressures of the gas in the pressure vessel are then absorbed by the next layer, the outer liner. This outer liner consists of a fiber-reinforced plastic material and can be formed, for example, by braiding or wrapping it around the inner liner.At least one, and in most cases both, ends of the pressurized gas container have a usually metallic end section attached, also known as a boss. This boss typically serves to support and stabilize the tank and to accommodate valve assemblies, in particular safety valves or an on-tank valve (OTV).

[0004] Particular importance is now attached to the tight seal of the inner liner to the end section. A suitable connection must be used to ensure sufficient sealing. According to the prior art, it is known to wrap the inner liner around part of the end section on the outside and then seal it by wrapping it with fibers of the fiber-reinforced outer liner. This is relatively complex and often results in an unreliable seal.

[0005] US patent 2012 / 0 085 727 A1 discloses a pressurized gas container in which the end section is formed in two parts: the actual end section, which has a bore, and a connecting sleeve mounted in the bore, which can later be screwed onto, for example, a valve. In the design according to the US publication, the inner liner is clamped tightly between the end section and the connecting sleeve screwed into the end section. For this purpose, at least one of the parts, i.e., either the end section and / or the connecting sleeve, has a groove with a corresponding seal, such as a sealing ring. Due to the purely form-fit connection in the sealing area, this design carries the risk of potential leakage, especially in applications where vibrations, shocks, or similar factors cannot be completely prevented, as these could potentially lead to the sealing connection loosening.

[0006] Another design of this type is also known from DE 10 2011 011 649 A1. In this design, the end section also contains a connecting sleeve, which is connected to the inner liner and sealed by a sealing ring in the threaded area between the connecting sleeve and the end section. To create a reliable connection between the inner liner and the connecting sleeve, a very complex connecting element in the form of a retaining sleeve is provided, which is connected to the inner liner on one side and to the connecting sleeve on the other by a push-fit or snap-fit ​​connection. The design is exceptionally complex and expensive to manufacture, as it comprises several individual parts that require complex manufacturing and forming processes.

[0007] From DE 10 2014 207 069 A1, a connection element for a pressure tank is known which can be inserted into an opening of the pressure tank and has a plug element and a counter element that at least partially encloses the plug element, wherein an outer side of the plug element and an inner side of the counter element form a tapered recess, so that a tank wall of the pressure tank can be clamped in the recess of the connection element.

[0008] The object of the present invention is to provide an improved pressurized gas container according to the preamble of claim 1, which in particular avoids the aforementioned disadvantages.

[0009] According to the invention, this problem is solved by a pressurized gas container having the features in the characterizing part of claim 1. Advantageous embodiments and further developments are described in the dependent claims. Claim 9 also specifies a particularly preferred use for the pressurized gas container.

[0010] The pressure gas container constructed according to the invention is designed in such a way that the material of the inner liner is bonded directly or via a suitable intermediate layer to the material of the connecting sleeve. This bonded connection, for example, an adhesive or welded joint, between the inner liner and the connecting sleeve results in a very simple and highly reliable structure with regard to leak tightness. The inner liner is connected to the connecting sleeve in such a way that a reliable seal of the storage volume within the inner liner is ensured. This structure, consisting of the inner liner and the bonded connecting sleeve, then simply needs to be joined with the end sections and completed, for example, by braiding and / or wrapping it with the fiber-reinforced plastic material through the outer liner. The structure is simple, has few components, and is very leak-proof and reliable.The material-bonded connection also reliably prevents the connection from loosening, for example due to vibrations or the like.

[0011] In the pressure gas container according to the invention, it is further provided that the inner shell is connected to the end face of the connecting sleeve facing the interior of the storage volume.

[0012] Connecting the inner sleeve only to the end face of the connector sleeve provides a structure that is extremely easy to assemble, as there are no parts protruding laterally beyond the inner sleeve that could potentially be damaged during assembly of the inner sleeve in the end section.

[0013] According to an advantageous further development of the idea, the material-bonded connection is preferably designed as a welded joint.

[0014] A further highly advantageous embodiment of the pressurized gas container according to the invention provides that the connecting sleeve has a connection contour directed towards the interior of the storage volume with at least two different planes. Such a connection contour with at least two different planes, which can be realized, for example, with a groove machined into the end face, a stepped design of the end face, or the like, provides a larger surface area in the region of the end face, so that a very good and reliable material-bonded connection of the inner liner to the end face of the connecting sleeve can be achieved.

[0015] In a particularly advantageous embodiment of the pressurized gas container according to the invention, it can further be provided that the connecting sleeve is coated or overmolded with an intermediate layer, at least on its end face facing the interior of the storage volume, wherein the material of the inner shell is bonded to the intermediate layer. Such an intermediate layer can be applied, in particular, to the preferably metallic connecting sleeve by coating or overmolding. The intermediate layer can then ensure that a very good bond, for example a very good weld, occurs between the material of the inner shell and the intermediate layer, which in turn is correspondingly well bonded to the material of the connecting sleeve. This further improves the adhesion of the inner shell to the connecting sleeve.By connecting the end face of the connector sleeve to the inner sleeve, the volume of the intermediate layer can be significantly reduced. This makes it possible to use very high-quality materials that are readily available on the market and specifically developed for hybrid systems, i.e., plastic-metal composites. Due to the comparatively small volume, the high cost of such materials is of minor importance. However, they can significantly improve adhesion.

[0016] In a further advantageous embodiment of the pressurized gas container according to the invention, the connecting sleeve can be glued into the bore of the end section. Such a connecting sleeve glued into the bore of the end section is particularly simple and efficient to assemble. By eliminating the need for a screw connection, the stress on any existing connection between the connecting sleeve and the inner liner can be reduced, thus enabling very simple and reliable assembly. Preferably, the connecting sleeve has a contour with a constant outer cross-section, allowing it to be inserted into the bore very easily.

[0017] A further highly advantageous embodiment of the pressure gas container according to the invention provides that the bore in the end section has a collar on the side facing away from the storage volume. Such a design is ideal with regard to assembly. The connecting sleeve can be inserted through the bore, which is preferably already coated with adhesive, from the future interior of the pressure gas container towards the exterior. The adhesive can then be activated and the bond formed. The collar present in this advantageous embodiment of the invention also provides mechanical securing of the connecting sleeve in the end section, as it is held in place by the collar and cannot be displaced outwards by the pressure later prevailing in the pressure gas container.The assembly process is exceptionally simple, yet very reliable, and very cost-effective due to the easy-to-assemble parts and their small number.

[0018] According to an advantageous embodiment of the pressure gas container according to the invention, the connecting sleeve can now be made of a metallic material, in particular steel or stainless steel. Such a connecting sleeve made of steel or stainless steel is very resistant in the area of ​​its thread, so that even with repeated screwing in and out of a valve device or similar, there is no risk of seizing and thus of leakage or damage.

[0019] Furthermore, by using a connecting sleeve made of steel or stainless steel, the material of the end section that receives the connecting sleeve can be designed almost arbitrarily. According to an advantageous embodiment, it is conceivable to design this section from aluminum, as has been done previously. However, according to a particularly favorable and advantageous embodiment of the pressurized gas container according to the invention, it is also possible to use a fiber composite material for the end section instead. Such a fiber composite material gains the necessary resistance to wear and galling in the threaded area from the connecting sleeve and can be manufactured with the majority of its volume from this lightweight and stable fiber composite material. This makes the construction of the pressurized gas container itself much lighter, which is a decisive advantage, especially for use in mobile systems such as vehicles.

[0020] As already mentioned, the pressure gas container according to the invention can be manufactured very simply and efficiently and is exceptionally reliable and safe. It is particularly suitable for applications where correspondingly large quantities must be produced while simultaneously meeting very high safety requirements for the pressure gas container. One such application could be the storage of hydrogen or natural gas in a vehicle. The particularly preferred use of the pressure gas container according to the invention is therefore the storage of hydrogen or compressed natural gas in a vehicle, for example in a fuel cell vehicle or a vehicle with an internal combustion engine that uses the gases as fuel.

[0021] Further advantageous embodiments of the pressure gas container according to the invention will become apparent from the exemplary embodiment, which is described in more detail below with reference to the figures.

[0022] This shows: Fig. 1 a cross-section through an end section of a pressurised gas container according to the invention; Fig. 2 an enlarged section A from the representation in Fig. 1; Fig. 3 a representation analogous to the enlarged section A in a first alternative execution variant; Fig. 4. A representation analogous to the enlarged section A in a second alternative version; and Fig. 5 a representation analogous to the enlarged section A in a third alternative execution variant.

[0023] In the presentation of the Fig. Figure 1 shows a sectional view of one end of a pressurized gas container 1, which is not shown in its entirety. The pressurized gas container 1 essentially consists of an inner shell 2, the so-called liner 2, and an outer shell 3 made of fiber-reinforced plastic, for example, a plastic reinforced with carbon fibers or aramid fibers. This fiber-reinforced plastic can, for example, be wound and / or braided and then solidified by curing a plastic matrix, which is either already present on the fibers or is subsequently applied.The outer shell 3 has the task of mechanically absorbing the pressure load, while the inner shell 2, which is unsuitable for this purpose, is made of a suitable plastic material in one or more layers – possibly also metallic – which are primarily intended to achieve diffusion tightness against the enclosed gas, for example, hydrogen. Furthermore, an end section 4, the so-called boss, is shown in the diagram. Fig. 1 can be seen in cross-section. This has a bore 5 in its interior, into which a connecting sleeve, in this case a threaded sleeve 6, is inserted. To prevent the connecting sleeve 6 from being forced outwards by the pressure inside the pressure vessel 1, as shown in the illustration of the Fig. 2, also shifted upwards, indicates that bore 5 at its upper end in the representation of the Fig. 2 a collar 7 which forms a mechanical stop for the connecting sleeve 6 in the bore 5. In addition, the connecting sleeve 6 is bonded to the material of the end section 4 in the bore 5. This is indicated by a dotted adhesive layer 11 in the enlarged view of section A in Fig. 2 to recognize.

[0024] The material of the inner shell 2 is welded to the end face 8 of the connecting sleeve 6, as shown in the illustration of the Fig. 1 and Fig. 2. Additionally, an intermediate layer 9 is sprayed onto the end face 8 of the connecting sleeve 6, which is composed in such a way that it ensures, on the one hand, a very tight and secure bond to the metallic material of the connecting sleeve 6 and, on the other hand, a good and secure weld connection with the material of the inner sleeve 2. To improve the adhesion of the intermediate layer 9 to the end face 8 of the connecting sleeve 6, this layer is formed in several levels, as shown in the illustration. Fig. 1 and Fig. 2, for example, is a projecting central section of the front face 8. Alternatives to this connection are shown in the Fig. 3 - 5 can be recognized, whereby in the representation of the Fig. 3 a groove is incorporated into the front face and shown in the illustrations of the Fig. 4 and Fig. 5. A stepped design of the front face 8 is implemented. All of these are conceivable solutions, which will be discussed in detail later.

[0025] The connecting sleeve 6 glued into the end section 4 also has, as can be seen in the illustration of the figures, a thread 10 into which corresponding connecting elements, for example an on-tank valve, can later be screwed.

[0026] The connecting sleeve 6 can be mechanically pre-machined very easily and efficiently and can have a corresponding thread 10, which is useful and intended for later use. For example, different thread pitches, thread types, or thread diameters can be implemented easily and efficiently without having to change the entire design. The connecting sleeve 6 is then glued into the bore 5 of the end section 4 via the adhesive bond 11 and subsequently, in the embodiments shown in the illustration, Fig. 1, Fig. 2 and Fig. 4 is gas-tightly overmolded with the intermediate layer 9, whereby this overmolding could in principle also take place before the insertion of the connecting sleeve 6 into the end section 4. Subsequently, the inner shell 2 is welded during the formation of the Fig. 1, Fig. 2 and Fig. 4 to the intermediate layer 9 and in the other configurations according to the Fig. 3 and Fig.5 is welded directly to the end face 8 of the connecting sleeve. This creates a very reliable and tight structure, which is then completed with the outer sleeve 3 in a known manner, for example, by wrapping and / or braiding it with the fiber material and subsequently impregnating and curing it with a plastic matrix. An alternative to gluing the connecting sleeve 6 can also be press-fitting, especially if both the end section 4 and the connecting sleeve 6 are made of metal. The connecting sleeve 6 can be made of steel, for example, stainless steel. The end section 4 can be manufactured very simply and efficiently from aluminum. The end section 6 can then be manufactured simply and efficiently, for example, by injection molding or forging. This is already common practice for current end sections according to the state of the art.However, there is a risk that a screwed-in valve assembly can easily seize, requiring very complex post-treatment, such as anodizing. This is unnecessary when using a connecting sleeve, for example made of steel. This makes the design very simple and cost-effective to manufacture, while still allowing the advantages of the lightweight metal to be utilized for the majority of its volume.

[0027] Furthermore, it is possible to manufacture the end section 4 from a non-metallic material, for example, a fiber composite material, a fiber-reinforced plastic, or, in principle, even a ceramic material or similar. Such a construction is made possible in particular by using the connecting sleeve 6 made of steel, since the connection can be made primarily by bonding, and thus a high-strength thread can be introduced into the end section 4 by using the connecting sleeve 6.

[0028] In principle, with any design of the end section 4, but especially when it is made of a fiber-reinforced composite material, it is also conceivable to design the shape of the outer connecting sleeve and the inner bore 5 of the end section 4 in such a way as to create a positive fit. For example, a polygonal shape could be used to prevent the connecting sleeve 6 from twisting, even without the adhesive 11.

[0029] If the end section 4 is made of fiber-reinforced composite material, it would also be conceivable to provide the connecting sleeve 6 with corresponding external protrusions, fins, or the like, which would enable an additional positive fit with the fiber composite material. In this case, the connecting sleeve 6 would thus be practically integrated into the end section during the manufacturing of the fiber composite material of the end section 4 and therefore firmly and securely connected to it.

Claims

[1] Compressed gas container (1) with a storage volume surrounded by an inner shell (2) made of plastic material and at least one outer shell (3) made of fiber-reinforced plastic, with at least one end section (4) attached to one end of the storage volume, wherein a connecting sleeve (6) is arranged in a bore (5) of the end section (4), wherein the material of the inner shell (2) is materially connected to the material of the connecting sleeve (6) directly or via a suitable intermediate layer (9), and the inner shell (2) is connected to the end face of the connecting sleeve (6) facing towards the interior of the storage volume. [2] Compressed gas container (1) according to claim 1, characterized by that the inner shell (2) is welded to the connecting sleeve (6). [3] Compressed gas container (1) according to one of claims 1 or 2, characterized bythat the connecting sleeve (6) has a connecting contour directed towards the interior of the storage volume with at least two different planes. [4] Compressed gas container (1) according to one of claims 1 to 3, characterized by that the connecting sleeve (6) is coated or overmolded with an intermediate layer (9) at least on its end face (8) facing the interior of the storage volume, wherein the material of the inner shell (2) is welded to the intermediate layer (9). [5] Compressed gas container (1) according to one of claims 1 to 4, characterized by that the connecting sleeve (6) is glued into the bore (5) of the end section (4). [6] Compressed gas container (1) according to one of claims 1 to 5, characterized by that the connecting sleeve (6) is made of a steel material, in particular of stainless steel. [7] Compressed gas container (1) according to one of claims 1 to 6, characterized bythat the bore (5) in the end section (4) has a collar (7) on the side facing away from the storage volume. [8] Compressed gas container (1) according to one of claims 1 to 7, characterized by that the end section (4) consists of a fiber composite material. [9] Use of the compressed gas container (1) according to one of claims 1 to 8, as a storage volume for hydrogen or compressed natural gas in a vehicle.

Images