DE102019134165A1 - Method of manufacturing a pressure vessel and pressure vessel - Google Patents

Abstract

The technology disclosed here relates according to the invention to a method for producing a pressure vessel 5 for gaseous fuels, an outer layer 30 made of a metallic material, which surrounds a liner 10, being provided and processed by means of a metal spinning method. According to the invention, the technology disclosed here also relates to an associated pressure vessel 5.

Description

The technology disclosed here relates to a method for producing a pressure vessel for gaseous fuels and a pressure vessel.

Pressure vessels can be used, for example, in motor vehicles to store gaseous fuel such as hydrogen. It is typically required that they can be produced easily and that they have a particularly low permeability for the gaseous fuel stored therein. Pressure vessels for hydrogen are known, for example, which are only made of a metal alloy which is impermeable to hydrogen. Corresponding metal alloys are expensive, however. Other known pressure vessels are made, for example, from a CFRP reinforcement, with a liner typically being present on the inside, which ensures a low permeability of hydrogen. However, the choice of materials is also limited here.

It is a preferred object of the technology disclosed here to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution. In particular, it is a preferred object of the technology disclosed here to provide an alternative, for example easier to manufacture, pressure vessel. Further preferred objects can result from the advantageous effects of the technology disclosed here. The objects are achieved by the subject matter of the independent claims. The dependent claims represent preferred configurations.

• - Bereitstellen, bevorzugt Herstellen einer Außenschicht aus einem metallischen Material, wobei die Außenschicht einen Liner umgibt,
• - Bearbeiten der Außenschicht mittels eines Metall-Spinning-Verfahrens.

The technology disclosed here relates to a method for manufacturing a pressure vessel for gaseous fuels, with the following steps:

• - Providing, preferably producing, an outer layer from a metallic material, the outer layer surrounding a liner,
• - Processing of the outer layer by means of a metal spinning process.

It has been shown that a production process for pressure vessels can be greatly simplified by such a procedure, since a metallic material including the liner can be brought into its desired shape by means of a metal spinning process. The use of a liner provides protection against the leakage of hydrogen. This allows a much greater freedom in the selection of metallic materials, it being possible, for example, to use metallic materials which are easier to process or have a lower purchase price.

The outer layer is typically that layer which delimits the finished pressure vessel from the outside. The liner can in particular form a hollow body in which the gaseous fuel is stored. The liner can in particular be made of a metal, a metal alloy or a plastic. For example, a liner made of aluminum or an aluminum alloy is expediently formed. The fuel is stored in the liner and the liner is usually responsible for the tightness of the pressure vessel. If, for example, hydrogen is stored, the liner is usually designed to prevent hydrogen permeation. A metallic design can be designed to be load-bearing as well as, like a polymer liner, not to be load-bearing. Usually, the liner contour is chosen to be as thin as possible, since the strength of the outer layer is significantly higher and a thinner overall wall thickness can therefore be achieved. For example, the maximum wall thickness of the liner can be less than 70 mm, less than 30 mm, preferably less than 10 mm or 5 mm. Like the pressure vessel, the liner usually has an elongated, preferably cylindrical shape with usually arched end areas. The end areas and a generally cylindrical circumferential area arranged between them are particularly advantageously formed in one piece

Processing by means of a metal spinning process can in particular take place in such a way that a tool is applied from the outside, which tool presses the outer layer inwards in a targeted manner. In this way, for example, end regions or domes can be formed. A shape can be used for this, which will be discussed in more detail below.

• - Bereitstellen, bevorzugt Herstellen des Liners,
• - Bereitstellen, bevorzugt Herstellen der Außenschicht,
• - Aufschieben der Außenschicht auf den Liner.

The following steps are preferably carried out before the provision or production of the outer layer surrounding the liner:

• - Provision, preferably production of the liner,
• - Providing, preferably producing, the outer layer,
• - Sliding the outer layer onto the liner.

The liner can in particular be in a shape which corresponds completely or at least along a substantial part of an axial extension of a cylindrical shape. A deformation can be present in particular at the end regions in order to adapt the desired shapes of a finished pressure vessel. Even before it is installed in the pressure vessel, the liner is typically stable enough to hold such a shape. The procedure described here enables the liner and outer layer to be easily brought together, with then the metal spinning process can be used.

In particular, the liner can be provided with one or more bosses attached to it. Corresponding bosses can be made of metal, for example. Valves or other units can be installed in bosses, for example. By providing or manufacturing the liner including the bosses attached to it, production is simplified, since these can be attached to the liner more easily outside or independently of the outer layer.

The liner can in particular be inflated after the outer layer has been pushed onto the liner, but expediently before the outer layer is processed. In this way, for example, the diameter of the liner can be increased at least slightly so that it adapts to the inner diameter of the outer layer. As a result, the best possible utilization of the available volume can be achieved. Alternatively, the outer layer can also be molded onto the liner. It is also possible to connect the liner and the outer layer to one another, for example by means of an adhesive process or a thermal connection.

At least one boss is preferably introduced into the outer layer before the machining of the outer layer. This can be done, for example, as just described, that is to say attached to the liner. The boss can serve as a mold, especially in the metal spinning process. For example, it can serve as a basic shape or as a basic shape. In particular, two bosses can be used, which can typically be arranged at respective opposite longitudinal ends. This allows a particularly efficient procedure in production, since the boss, which is often necessary anyway, can serve as a mold for the metal spinning process and thus no additional tool is required. The outer layer is particularly well adapted to the boss, with the outer layer and boss typically also having to be well adapted in shape in the finished pressure vessel.

The metallic material can in particular have a nickel content of less than 13%, less than 10%, less than 5% or less than 1%. This is in particular the metallic material of the outer layer. Such a nickel content can be selected because the liner ensures that the hydrogen or other gaseous fuels are kept within the liner and thus the metallic material no longer has to ensure that the permeability is sufficiently low. Such low permeability is typically achieved with a high nickel content. Corresponding metallic materials with a high nickel content are expensive, however.

The metallic material preferably has a yield strength of more than 300 MPa, more than 1,000 MPa or more than 1,500 MPa. The use of materials with such a high yield point is possible because the liner ensures the necessary low permeability and keeps the gaseous fuel, for example hydrogen, away from the metallic material. A yield strength between 1,500 MPa and 1,600 MPa has proven particularly advantageous.

At least one rounded area is preferably formed at one axial end by the metal spinning process. Such a rounded area can in particular be called a dome. In particular, the metal spinning process can also be used to form rounded areas at both axial ends.

According to one embodiment, a heat protection layer is introduced between the liner and a region of the outer layer that is machined or to be machined by metal spinning processes. As a result, thermal processing can be used during the metal spinning process or an increase in temperature can be accepted without causing thermal damage to the liner or increasing the risk thereof.

The technology disclosed here also relates to a pressure vessel which was produced by means of a method as described herein. With regard to the method, all variants described herein can be used.

The pressure vessel can in particular be used for a motor vehicle, for example passenger cars, motorcycles or utility vehicles. It is used to store fuel that is gaseous under ambient conditions. The pressure vessel can be used, for example, in a motor vehicle that is operated with compressed (also called “Compressed Natural Gas” or CNG) or liquefied (also called “Liquid Natural Gas” or LNG) natural gas or with hydrogen. The pressure vessel can be designed, for example, as a cryogenic pressure vessel or as a high-pressure gas vessel. High-pressure gas containers are designed to store fuel permanently at ambient temperatures at a nominal operating pressure (also called “nominal working pressure” or NWP) of approx. 350 barg (= overpressure compared to atmospheric pressure), further preferably of approx. 700 barg or more. A cryogenic pressure vessel is suitable for storing the fuel at the aforementioned operating pressures even at temperatures which are well below the operating temperature of the motor vehicle.

The technology disclosed here also relates to a pressure vessel which has an outer layer and an inner liner, a heat protection layer being arranged between the liner and the outer layer at least along one area. The pressure vessel can in particular be produced by means of a method described herein. The heat protection layer can thereby avoid thermal damage to the liner, in particular during the process. It can also remain in the finished pressure vessel and, for example, take on the role of a well-known "shear ply" to avoid voltage peaks in the area of the transition between the metallic boss of the liner and the plastic of the liner. In particular, the fire protection layer can have a thickness between 2 mm and 3 mm.

In other words, for example, a plastic liner can be used as a hydrogen barrier or gas barrier in order to isolate a future metallic or steel casing from the gas. For example, a multi-layer liner can also be used to create an even better barrier.

A metal cylinder or steel cylinder with the suitable alloy, for example, can be pushed onto such a liner or plastic liner, the alloy typically being adapted to withstand the forces or the internal pressure to be expected. The inner diameter of the steel cylinder preferably corresponds to the outer diameter of the plastic liner. In particular, ends of a steel cylinder or outer layer can be progressively reshaped by means of a spinforming process or metal spinning process in order to form a dome contour.

The procedure described can prevent a metal alloy or steel alloy used from having to be gas or hydrogen compatible, since the material is not in direct contact with the gas. Nevertheless, in the design it can be taken into account that gas can also diffuse through the liner. If, for example, heat or fire are used during the metal spinning process, the plastic liner or liner can be protected with a fire protection film or fire protection mat or heat protection layer, which, for example, can also remain between the liner and the outer layer at the end of the process. The heat protection layer can be, for example, 2 mm to 3 mm thick.

An alternative embodiment for producing a pressure vessel is described below. The bosses of the future pressure vessel can be manufactured first. These can be attached to a metal spinning machine, where a metal cylinder or steel cylinder is deformed in order to obtain a pressure tank reinforcement with a dome contour. If the future pressure tank is to have two openings, the process is typically carried out on both sides. A liner, for example, can then be introduced in the interior, with the already completed casing serving as a tool for a rotomolding process. For example, a gap between the boss and the casing can first be closed. For example, a silicone joint can be formed. However, if, for example, the casing has already been deformed or pressed against an outer surface of the boss, it may also be that such a joint is no longer necessary or that it is only very small. For example, liquid plastic can then be introduced into the interior, which is then distributed on an inner surface as part of a rotomolding process. After appropriate curing, the finished pressure vessel is created.

• 1: Komponenten eines Druckbehälters während einer Herstellung,
• 2: einen Verfahrensschritt eines Metall-Spinning-Verfahrens,
• 3: einen fertigen Druckbehälter,
• 4: einen möglichen Übergang zwischen Außenschicht, Liner und Boss, und
• 5: einen alternativen Übergang.

The technology disclosed here will now be explained with reference to the figures. Show it:

• 1 : Components of a pressure vessel during manufacture,
• 2 : a process step of a metal spinning process,
• 3 : a finished pressure vessel,
• 4th : a possible transition between outer layer, liner and boss, and
• 5 : an alternative transition.

1 shows purely schematically components which can be used during a manufacturing process of a pressure vessel.

There is a liner on the inside 10 arranged. This already has at least approximately the shape that it should have in the finished pressure vessel. The liner 10 extends as shown along a longitudinal direction, which in the plane of the paper of 1 lies horizontally. There are respective bosses at both ends 20th , 25th on the liner 10 attached, with a corresponding attachment of the bosses 20th , 25th on the liner 10 was carried out in advance in manufacturing processes to be carried out separately.

The liner 10 is in an outer shell 30th arranged from a metallic material. The bosses 20th , 25th were attached to the liner 10 before inserting into the outer layer 30th attached.

From the state shown, the liner 10 are now initially inflated by means of an overpressure to be formed therein, so that it conforms to the inner diameter of the outer layer 30th ideally attaches. As a result, the best possible use of space can be achieved.

A metal spinning process can then be carried out to form domes at the two longitudinal ends. A corresponding process is shown schematically in 2 shown. To do this, there is a tool 40 used which from the outside to the outer layer 30th acts and deforms it inwards. The bosses 20th , 25th serve as the shape, ie the outer layer 30th is made by the tool 40 against the bosses 20th , 25th pressed. As a result, the best possible shape can be achieved.

After a process carried out on both sides, the in 3 Final state shown of a pressure vessel 5 reached. The interior becomes the outer layer 30th completely through the liner 10 lined, and at the end are the bosses 20th , 25th available. Tank valves or other components, for example, can be installed in these. Due to the particularly low permeability of the liner 10 it is no longer necessary for the gas to be stored that the outer layer 30th which ensures low permeability or is resistant to the gas to be stored, such as hydrogen. This allows a much greater freedom in the choice of material.

4th shows a possible transition between boss 20th , Outer layer 30th and liner 10 . There is the liner 10 Shaped so that he is on the border with the interior at the boss 20th is present. In an embodiment not shown, however, it is also possible that the liner is additionally or alternatively in a transition area 15 between boss 20th and outer layer 30th is arranged. As a result, the best possible tightness can be achieved.

5 shows a modified version, with an additional heat protection layer 22nd between liners 10 or boss 20th and outer layer 30th is arranged. This can damage the liner during a manufacturing process 10 by heating during production, for example during a metal spinning process. The heat protection layer can also be used in the finished pressure vessel 22nd remain, whereby it can, for example, compensate for tension.

For reasons of legibility, the expression “at least one” has been partially omitted for the sake of simplicity. If a feature of the technology disclosed here is described in the singular or indefinitely (e.g. the / a pressure vessel, the / a heat protection layer, etc.), the plurality of these should also be disclosed at the same time (e.g. the at least one pressure vessel, the at least one heat protection layer , Etc.).

The preceding description of the present invention is for illustrative purposes only and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

List of reference symbols

5:

pressure vessel

10:

Liner

20, 25:

Bosses

22:

Thermal protection layer

30:

Outer layer

40:

Tool

Claims (11)

Method for producing a pressure vessel (5) for gaseous fuels, with the following steps: - providing an outer layer (30) made of a metallic material, the outer layer (30) surrounding a liner (10), - Processing of the outer layer (30) by means of a metal spinning process. Procedure according to Claim 1 , the following steps being carried out before the outer layer (30) surrounding the liner (10) is provided: - providing the liner (10), - providing the outer layer (30), - sliding the outer layer (30) onto the liner (10) . Procedure according to Claim 2 - wherein the liner (10) is provided with one or more bosses (20, 25) attached thereto. Procedure according to Claim 2 or 3 - wherein after the outer layer (30) has been pushed onto the liner (10), but before the outer layer (30) is processed, the liner (10) is inflated and / or the outer layer (30) is molded onto the liner (10) and / or liner (10) and outer layer (30) are connected to one another. Method according to one of the preceding claims, - with at least one boss (20, 25) being introduced into the outer layer (30) before the machining of the outer layer (30), - The boss (20, 25) is used as a mold in the metal spinning process. Method according to one of the preceding claims, wherein the metallic material has a nickel content of less than 13%, less than 10%, less than 5% or less than 1%. Method according to one of the preceding claims, - wherein the metallic material has a yield strength of more than 300 MPa, more than 1,000 MPa or more than 1,500 MPa, or between 1,500 MPa and 1,600 MPa. Method according to one of the preceding claims, - At least one rounded area being formed at one axial end by the metal spinning process. Method according to one of the preceding claims, - a heat protection layer (22) being introduced between the liner (10) and an area of the outer layer (30) processed in the metal spinning process. Pressure vessel (5) which was produced by means of a method according to one of the preceding claims. Pressure vessel (5) which has an outer layer (30) and an inner liner (10), a heat protection layer (22) being arranged between liner (10) and outer layer (30) at least along one area.

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