Method for manufacturing a pressure vessel and pressure vessel

Abstract

The technology disclosed herein relates to a method for manufacturing a pressure vessel 10 for storing gaseous fuel, wherein a starting material for a wall 20 of the pressure vessel 10 is provided and a wall 20 is formed by direct energy deposition with the starting material. The technology disclosed herein further relates to a pressure vessel 10 manufactured accordingly.

Description

[0001] The technology disclosed herein relates to a method for manufacturing a pressure vessel and to a pressure vessel manufactured accordingly.

[0002] Pressure vessels are used, for example, to store gaseous fuels such as hydrogen or natural gas under pressure. They can be used, for instance, in mobile or stationary units to power an energy converter such as a fuel cell or a gas-powered combustion engine.

[0003] It is an object of the technology disclosed herein 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 herein to propose a method for manufacturing a pressure vessel that enables its simple and reliable production. Further preferred objects may arise from the advantageous effects of the technology disclosed herein. These objects are solved by the subject matter of the independent claims. The dependent claims represent preferred embodiments.

[0004] The technology disclosed herein relates to a method for manufacturing a pressure vessel for storing gaseous fuel. The method comprises the following steps: - Providing a starting material for a wall of the pressure vessel, and - Formation of a pressure vessel wall through direct energy deposition with the starting material.

[0005] Using this method, direct energy capture can be employed to manufacture a pressure vessel. This method has proven suitable for producing pressure vessels cost-effectively and reliably.

[0006] Direct energy deposition (DED) is a three-dimensional printing process. It uses a focused energy source, such as a plasma arc, laser, or electron beam, to melt material. This material can then be applied through a nozzle. Direct energy deposition can be used to add material to existing components, for repairs, or to manufacture entirely new parts.

[0007] Various materials can be used for the starting material. After the process is carried out, it forms the wall of the pressure vessel. Within the wall is an interior space in which the gaseous fuel can be stored, typically under pressure.

[0008] In particular, the starting material can be provided as wire. A wire is understood to be, in particular, a long, usually flexible, typically single-piece element with a relatively small diameter compared to its length. A wire is typically easy to handle; for example, it can be supplied on a wire spool and guided by suitable guides. Alternatively or additionally, the starting material can be provided, for example, as a powder. A powder is understood to be, in particular, a substance consisting of a large number of granules that have a small volume compared to the entire substance. A powder can be easily stored in a container and easily transported to its point of use by means of pouring and / or conveying processes.

[0009] In one embodiment of direct energy deposition, the starting material is melted by an electric arc. An electric arc is typically formed as an ionized region by a high current flow between two electrodes. In another embodiment, the starting material is melted by a laser beam. A laser beam is typically directed at the starting material so that energy is transferred into it, causing it to melt.

[0010] According to one definition, the starting material is metallic. The starting material can, for example, contain or consist entirely of steel and / or aluminum. Such materials have proven advantageous for typical applications. However, other starting materials can also be used. In this context, steel is understood to be a material consisting primarily of iron, usually with a small carbon content and possibly other components.

[0011] According to one embodiment, one or more partitions are formed within the wall by direct energy capture to create multiple chambers. Such partitions can provide additional stability and separation within the pressure vessel. In particular, the partitions can be oriented wholly or partially transversely to the adjacent surface of the wall. This has proven advantageous for the manufacturing process described herein and beneficial for stability.

[0012] The wall can be formed, in particular, starting from a connection element of the pressure vessel. This can specifically mean that the manufacture of the pressure vessel begins at a connection element and is formed from there. A connection element is understood to be, in particular, a region of the pressure vessel in which valves, sensors, and / or other components for the operation of the pressure vessel are located. A connection element can, for example, be formed at one end of a dome of the pressure vessel.

[0013] The wall can be designed such that a longitudinal axis of the wall is oriented obliquely to a vertical and / or obliquely to a principal axis of a machining tool. Such an oblique design has proven advantageous for typical process configurations. In particular, it enables advantageous guidance of a typical tool for direct energy capture. This will be discussed in more detail below. A vertical is understood to be an imaginary line perpendicular to the Earth's surface. A principal axis of a machining tool is typically the one along which material exits the tool to form the pressure vessel. Partitions can be oriented obliquely to the vertical and / or obliquely to the principal axis of the machining tool, particularly within the wall. This also allows for advantageous process configurations.

[0014] An inclined orientation can be understood, in particular, as an angle between the wall or partition and a reference point, such as the vertical or the main axis of the machining tool, that is neither zero nor 90°. For example, the angle may be at least 10°, at least 20°, at least 30°, at least 40°, or at least 50°. It may also be, for example, at most 50°, at most 60°, at most 70°, or at most 80°. In particular, an angle of 60° or more to the outer surfaces of the partitions may be used.

[0015] In particular, the wall can be manufactured in an approximately cuboid shape. This can refer specifically to a cross-section. Specifically, this can mean that the wall has a cuboid cross-section with rounded corners. As a special case, a cuboid shape can also be square. However, the formation of round or elliptical walls is also possible, for example.

[0016] The wall can be constructed from several overlapping layers, particularly as welded membranes. This allows for a certain degree of overlap to increase stability.

[0017] The wall can be designed, in particular, to have a wall thickness of at least 3 mm, at least 4 mm, at least 5 mm, at least 6 mm, at least 7 mm, at least 8 mm, at least 9 mm, at least 10 mm, or at least 11 mm. It can also be designed, in particular, to have a wall thickness of at most 4 mm, at most 5 mm, at most 6 mm, at most 7 mm, at most 8 mm, at most 9 mm, at most 10 mm, at most 11 mm, or at most 12 mm. In particular, high-strength and / or strong steel can be used for the wall. High-strength steel can be understood, in particular, to mean steel with a tensile strength of at least 1,000 MPa. Strong steel can be understood, in particular, to mean steel with a tensile strength of at least 1,700 MPa.

[0018] The wall can be formed around a mold. The mold can, in particular, define the final shape of the wall. In other words, the mold serves as a template for forming the wall.

[0019] The technology disclosed herein further relates to a pressure vessel for storing gaseous fuel, manufactured by a process as described herein. Reference may be made to all details of the process described herein.

[0020] In other words, hydrogen tanks or pressure vessels are often cylindrical or spherical to withstand high pressure. They can be made from materials such as carbon fibers or glass fibers. Alternatively, pressure vessels can be additively manufactured from steel or produced using powder bed 3D printing. However, cylindrical and spherical tanks or pressure vessels are not optimized for all installation spaces in a vehicle. Often, cuboid-shaped storage tanks or pressure vessels offer better space utilization. Such cuboid pressure vessels frequently feature internal reinforcement to prevent bulging under high pressure. It has been shown that these types of tanks can be manufactured more cost-effectively and reliably using direct energy capture, for example, compared to powder bed 3D printing.

[0021] The outer skin of, for example, an approximately cuboid-shaped pressure vessel can be manufactured using continuous weld seams. Internal reinforcements can connect two opposing surfaces and can be advantageously produced by angling the component. Alternatively, angled internal reinforcements are also possible.

[0022] In particular, the technology disclosed herein can be used to manufacture, for example, an approximately or completely flat and / or cuboid-shaped hydrogen tank or pressure vessel for gaseous fuel, especially for use in vehicles. The pressure vessel can, in particular, have internal reinforcements. The pressure vessel can be manufactured additively, especially without a powder bed, by means of continuous weld lines. In particular, this allows for the use of directed energy deposition. Internal reinforcements can connect opposing surfaces in the pressure vessel. The internal reinforcements can be produced, for example, by angling the pressure vessel. Accordingly, they can also be angled in the finished pressure vessel.

[0023] A pressure vessel, which can be manufactured in particular using the method described herein, may be suitable, for example, for a motor vehicle (e.g., passenger cars, motorcycles, commercial vehicles). The pressure vessel serves, in particular, for the storage of fuel that is gaseous under ambient conditions. The pressure vessel can be used, for example, in a motor vehicle powered by compressed natural gas (CNG), liquefied natural gas (LNG), or hydrogen. The pressure vessel is typically fluid-connected to at least one energy converter designed to convert the chemical energy of the fuel into other forms of energy. The pressure vessel may, for example, be a cryogenic pressure vessel or a high-pressure gas cylinder.High-pressure gas cylinders are designed to store fuel continuously at ambient temperatures at a nominal working pressure (NWP) of at least 350 bar (gauge pressure above atmospheric pressure) or at least 700 bar (gauge pressure). A cryogenic pressure vessel is typically suitable for storing fuel at the aforementioned operating pressures even at temperatures significantly lower (for example, more than 50 K or more than 100 K) than the operating temperature of the vehicle.

[0024] The technology revealed here will now be described using the figures as examples. The figures will be shown: Fig. 1: a pressure vessel, Fig. 2: a first state in the manufacture of a pressure vessel, Fig. 3: a second state in the manufacture of a pressure vessel, and Fig. 4: a final state after the manufacture of a pressure vessel.

[0025] Fig. Figure 1 schematically shows a pressure vessel 10. The pressure vessel 10 has a wall 20, shown here in a top view. In cross-section, the wall 20 is approximately cuboid, i.e., it is essentially cuboid-shaped, but with rounded corners. It extends along a longitudinal axis 21 and a transverse axis 22 perpendicular to it. The longitudinal axis 21 is longer than the transverse axis 22. This results in a cuboid shape in the top view shown. The wall 20, or the pressure vessel 10, is thus essentially shaped approximately like a cushion. In the direction perpendicular to the plane of the paper, Fig. The pressure vessel 10 also extends along the vertical axis 1, resulting in the aforementioned cushion shape.

[0026] Several partitions 30 are arranged within the pressure vessel 10. These divide the interior of the pressure vessel 10 into several chambers 35. According to one embodiment, the chambers 35 can be sealed off from each other, but they can also be fluidically connected. The partitions 30 also serve, in particular, to connect opposite sides of the pressure vessel 10. This prevents the wall 20 from swelling under high pressure, so that the pressure vessel 10 retains at least approximately its shape. In other words, forces between opposite parts of the wall 20 are transmitted by means of the partitions 30.

[0027] The Fig. Figures 2 to 4 show process steps for the manufacture of a pressure vessel 10, which, compared to the design of Fig. 1 is somewhat longer. The starting point is initially a connection element 25. This is shown at the very bottom of the figures, and in practice it can contain components such as fluidic connections or sensors. By means of direct energy deposition 40, material for forming the wall 20 is then deposited onto the connection element 25. The pressure vessel 10 also receives its shape in this process.

[0028] To achieve the state which is in Fig. As shown in Figure 2, material was initially deposited so that the already produced part of the wall 20 widens upwards on both sides. Further material can then be deposited, advantageously resulting in the production of the pressure vessel 10 transversely to a vertical. This means, in particular, that a developing longitudinal axis 21 of the pressure vessel 10 assumes a non-zero angle to the vertical. In the example of Fig. Figure 3 shows an angle of 45°. The pressure vessel 10 is then formed along this direction. Due to the inclined design of the pressure vessel 10, it is easy to form partitions 30 using the same manufacturing process, which are oriented transversely to the longitudinal axis 21. Typically, it is not possible to form horizontal surfaces of material using the presented method, at least not without considerable effort. Thus, the production of the partitions 30 would only be possible with significantly increased effort if the pressure vessel 10 were formed along the vertical. However, in the embodiment described here, in which the pressure vessel 10 is formed at an angle, the partitions 30 to be formed are also inclined, so that simple formation using the direct energy separation process is easily possible.

[0029] Fig.Figure 4 shows the finished pressure vessel 10. This can now be used according to its intended purpose.

[0030] In particular, the process described herein can utilize a combination of wire feeding and arc melting. This represents a sub-form of direct energy capture and has proven particularly advantageous for the production of pressure vessels. According to a further development, a finished pressure vessel 10 can be wrapped with tapes, for example, to increase its stability.

[0031] For the sake of readability, the phrase "at least one" has been omitted in some instances. Where a feature of the technology disclosed herein is described in the singular or indefinitely (e.g., the pressure vessel, the tool, etc.), its plural forms are also intended to be disclosed (e.g., the at least one pressure vessel, the at least one tool, etc.).

[0032] The preceding description of the present invention serves only for illustrative purposes and not to limit 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. Reference symbol list 10 pressure vessels 21 Longitudinal axis 22 Transverse axis 25 Connection element 30 partition walls 35 chambers

Claims

[1] Method for manufacturing a pressure vessel (10) for storing gaseous fuel, the method comprising the following steps: - Providing a starting material for a wall (20) of the pressure vessel (10), and - Formation of a wall (20) of the pressure vessel (10) by direct energy deposition with the starting material. [2] Method according to claim 1, wherein the starting material is provided as wire. [3] Method according to claim 1 or 2, wherein the starting material is provided as a powder. [4] Method according to one of the preceding claims, wherein in direct energy deposition the starting material is melted by an electric arc. [5] Method according to one of the preceding claims, wherein in direct energy deposition the starting material is melted by a laser beam. [6] Method according to any of the preceding claims, wherein the starting material is metallic, and / or wherein the starting material contains or consists of steel and / or aluminium. [7] Method according to one of the preceding claims, wherein one or more partitions (30) are formed by direct energy separation to form several chambers (35) within the wall (20). [8] Method according to claim 7, wherein the partition walls (30) are aligned wholly or partially transversely to adjacent surfaces of the wall (20). [9] Method according to one of the preceding claims, wherein the wall (20) is formed starting from a connecting element (25) of the pressure vessel (10). [10] Method according to one of the preceding claims, wherein the wall (20) is designed such that a longitudinal axis (21) of the wall (20) is oriented obliquely to a vertical and / or obliquely to a principal axis of a machining tool. [11] Method according to claim 10, wherein partition walls (30) within the wall (20) are oriented obliquely to the vertical and / or obliquely to the main axis of the machining tool. [12] Method according to one of the preceding claims, wherein the wall (20) is produced at least approximately cuboid in shape. [13] Method according to one of the preceding claims, wherein the wall (20) is made from several superimposed sheets. [14] Method according to any of the preceding claims, wherein the wall (20) is formed around a mold. [15] Pressure vessel (10) for storing gaseous fuel produced by a method according to one of the preceding claims.

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