Method for forming a joint from one reinforcing fiber or a plurality of reinforcing fibers and method for manufacturing a pressure vessel

Abstract

The technology disclosed herein relates to a method for producing a connection (23) between walls (21, 22) of a wall body (20) of a pressure vessel (10) from reinforcing fibers (30), wherein the reinforcing fibers (30) are gripped by tufting needles (300) and penetrated through the respective walls (21, 22) and form a loop (35), through which a support element (40) is introduced. The technology disclosed herein furthermore relates to a method for manufacturing a pressure vessel (10) according to the invention.

Description

Technical Field

[0001] The technology disclosed herein relates to a method for forming a connection between the walls of a pressure vessel using one or more reinforcing fibers. The technology disclosed herein also relates to a method for manufacturing a pressure vessel. Background Technology

[0002] Pressure vessels are used, for example, in motor vehicles, to store gaseous fuel. This fuel can then be used to power energy converters such as fuel cells or gas-powered internal combustion engines.

[0003] In the further promotion of gas-powered vehicles, it is increasingly important to make full use of the structural space within motor vehicles to house pressure vessels. However, a problem arises: the pressure vessel must also be able to withstand the pressures within it, which depends not only on the wall thickness but also on its shape. A circular cross-section is typically ideal in terms of compressive strength, however, it often fails to achieve efficient use of the available structural space.

[0004] It is known in principle that reinforcing fiber connections can be introduced into pressure vessels to achieve sufficient compressive strength even in shapes deviating from a circular cross-section. Such reinforcing fibers can absorb forces on the walls and stabilize the walls together. However, the introduction of such reinforcing fibers is often difficult. Summary of the Invention

[0005] The preferred objective of the technology disclosed herein is to reduce or eliminate at least one drawback of prior known solutions or to propose an alternative solution. In particular, a preferred objective of the technology disclosed herein is to provide a method by which the connection of reinforcing fibers can be simplified. Other preferred objectives can be derived from the advantageous effects of the technology disclosed herein.

[0006] The technology disclosed herein relates to a method for forming a connection between the walls of a pressure vessel using one or more reinforcing fibers, comprising method steps that are repeated in sequence for forming the connection or connection between a first wall and a second wall of the pressure vessel:

[0007] - Each reinforcing fiber is gripped at a gripping point by a tufting needle, with a first segment and a second segment of the reinforcing fiber extending from the gripping point;

[0008] - The first wall is pierced by a tufting needle, and then the second wall is pierced by a tufting needle, so that the gripping point penetrates the first and second walls, and the first and second segments pass through the second and first walls;

[0009] - A loop is formed between the gripping point and the second wall; and

[0010] - Introduce the support element into the ring.

[0011] Using this method, reinforcing fibers can be used to form connections in pressure vessels in a very simple and reliable manner. Tufting needles grip the corresponding reinforcing fibers at gripping points, from which first and second segments of the reinforcing fibers extend. This can also be explained as the gripping points dividing the reinforcing fibers into segments from which two segments extend. When the tufting needle penetrates the first wall, the reinforcing fiber is typically driven at the gripping point. If the tufting needle has penetrated the first wall, the gripping point also penetrates the wall. The two segments of the reinforcing fiber then extend from the tufting needle, such that the segments penetrate the first wall through the formed holes. The same applies further to the second wall, which is penetrated in a further, typically linear, movement of the tufting needle. The segments then, viewed from the gripping point, first pass through the second wall and then through the first wall.

[0012] If the reinforcing fiber is reguided only on one side or unevenly during the process, the gripping point moves along the reinforcing fiber during the movement of the tufting needle. Typically, the gripping point is understood as a point on the reinforcing fiber at which the tufting needle grips and can therefore manipulate it, for example, because the reinforcing fiber passes through the eyelet of the tufting needle at the gripping point or is otherwise gripped. Each of these segments extends from the gripping point. These segments are also variable and can then be viewed along the reinforcing fiber.

[0013] When tufting is mentioned in the context of the process, it typically refers to the corresponding tufting process for treating one of the reinforcing fibers. If multiple reinforcing fibers are being treated simultaneously, the process typically involves one tufting process for each reinforcing fiber.

[0014] The ring can provide, in particular, the space required for the support element. The ring is specifically formed within the corresponding reinforcing fibers. If the support element is introduced into the ring, the reinforcing fibers that were just introduced can no longer be pulled across the second wall. Thus, the result of maintaining the tufting is that the first and second segments of the reinforcing fibers now extend between the two walls and can therefore subsequently serve as a connection that can absorb the forces acting on the walls.

[0015] This allows, for example, the two walls to be constructed flat, which is, in principle, a less stable implementation for absorbing internal pressure compared to a circular wall. However, the connecting portion can absorb the applied forces and stabilize the walls together. Thus, for example, a wall thickness can be used with less wall thickness than would be required without such a connecting portion.

[0016] The connecting portion can be understood, in particular, as a segment or combination of reinforcing fibers that extends between two walls of the wall body and stabilizes the walls relative to each other. The connecting portion typically extends within the internal space of a pressure vessel.

[0017] Reinforcing fibers are typically long fibers with defined tensile strength that can absorb forces. Tufted needles are, for example, elongated needles with pointed tips, which may have eyelets or include areas with forks for gripping the reinforcing fibers.

[0018] The walls typically enclose an interior space in which gaseous fuel can be stored in a pressure vessel. Each of the walls is a component of the wall body, which may also have other components, such as curved sections that connect the walls to each other.

[0019] The sequence of connecting parts can be understood, in particular, as multiple parallel connecting parts, for example, arranged directly side by side and / or along a line. A particular advantage of the technique disclosed herein is that multiple tufting needles, or even many tufting needles, can be used, and they can move together in particular. For this purpose, they can be mounted, in particular, on a common support or guide device. This allows for parallel and particularly efficient manufacturing.

[0020] The support element can be, in particular, a stabilizing element that prevents the reinforcing fibers from being pulled through the wall again after being introduced into the ring. In its manufactured state, the support element can also be considered for suitable force distribution. The support element can be, in particular, a body having a longitudinal direction and a cross-section that is constant transversely to the longitudinal direction. Further possible embodiments are discussed below.

[0021] The first wall can be parallel to the second wall. This enables, for example, a fitting with a flat mounting space or more generally with a mounting space having a shape complementary to the wall structure.

[0022] The wall can be made, in particular, of a wound carbon fiber layer. This carbon fiber layer has proven useful in the manufacture of pressure vessels. The carbon fiber layer can be wound, particularly in a separate winding process, so that reinforcing fibers can then be introduced into the wall formed therein. The wall can then be impregnated or covered with a matrix, for example, to establish strength and / or airtightness. Here, initially, only the wall with the aforementioned fibers can be placed in the final state. This final state can be, for example, a fiber-reinforced layer in which the fiber-composed wall is embedded in the matrix, i.e., reinforced therein. The wound carbon fiber layer has the particular advantage that it can easily create small openings when tufting needles penetrate. Such openings can be created, in particular, in such a way that adjacent carbon fibers are slightly pushed to the side. It is also possible to use other fibers as carbon fibers. Instead of a subsequent application of the matrix, fibers covered with a matrix material can also be used for the wall, for example.

[0023] The reinforcing fibers can be made, in particular, of aromatic polyamides or carbon fibers. Such materials have proven feasible for typical applications. However, other materials may also be used.

[0024] In particular, multiple tufting needles can move simultaneously. This can be achieved, for example, by mounting the tufting needles onto a common guide device. This enables highly efficient manufacturing because many tufting needles can move at the same time. Synchronized movement is especially understood as similar and simultaneous movement. In other words, the tufting needles perform the same movement simultaneously.

[0025] Whenever the term "reinforcing fiber" is mentioned within the scope of the method, referring to the use of the reinforcing fiber to perform specific method steps or the reinforcing fiber having specific properties, then the case where multiple connections are simultaneously constructed along a sequence typically refers to performing the method steps with each reinforcing fiber or having each reinforcing fiber having the aforementioned properties.

[0026] Preferably, reinforcing fibers are supplied or unwound from a reserve device during tufting through the wall. Such a reserve device can be, for example, a coil. Typically, a section is secured during tufting, either directly or by anchoring or fastening to, for example, the wall or matrix, particularly at the end of the reinforcing fiber, or where a connection already exists from which the reinforcing fiber extends and which is typically tightened when tufting the next connection. When the first section is correspondingly secured, a second section can be supplied, particularly from the reserve device. This can be particularly automatic, i.e., during tufting through the tufting needle, tension is applied to the second section and thus the second section is unwound from the reserve device, for example, a coil. However, active feeding is also possible.

[0027] The ring can be formed, in particular, by pulling back the tufted needles. This releases the stress acting on the reinforcing fibers, and the ring is formed based on the friction of the reinforcing fibers remaining in the wall. The pulling back for forming the ring can be, in particular, in a direction opposite to the direction in which the reinforcing fibers are embedded.

[0028] In particular, the method can be implemented such that the tufting needles are pulled back only to such an extent during the pull-back to form the loop that the tufting needles also penetrate the second wall, that is, the longitudinal ends of the reinforcing fibers do not penetrate through the second wall. This avoids the reinforcing fibers penetrating through the second wall without forming a loop.

[0029] In particular, eyelets may be formed in each tufting needle. These eyelets may be positioned, for example, directly adjacent to the tip or pointed end of the tufting needle. The reinforcing fibers to be embedded in the tufting needle can extend through the corresponding eyelets and remain at least substantially within them during the methods described herein. This can be understood, in particular, as the gripping of the reinforcing fibers. The tufting needle can guide the reinforcing fibers in this way and, for example, drive them through the wall. When the support element has been guided through the ring, the reinforcing fibers are prevented from being fully or largely pulled back as the eyelets are retracted. Instead, the reinforcing fibers typically extend through the eyelets when the tufting needle is pulled back.

[0030] Alternatively, the forked longitudinal ends of tufted needles can also be used to hold the reinforcing fibers.

[0031] Generally, gripping can be understood as a connection between tufting needles and reinforcing fibers, which allows the tufting needles to manipulate the reinforcing fibers, for example, by driving the reinforcing fibers through a wall as mentioned above, thereby forming a connection. The gripping can be maintained identically through multiple connections to be formed, for example when using eyelets, or each time it is re-established, for example when using forked longitudinal ends.

[0032] Ideally, only one support element is introduced into all loops of a sequence. This allows for particularly efficient manufacturing. However, multiple support elements can also be used.

[0033] The support element may, in particular, have a commutation surface that bends to redirect the one or more reinforcing fibers. The reinforcing fibers can thus be guided around the support element along the commutation surface, and force can be introduced into the one or more reinforcing fibers along the commutation surface. The commutation surface may, in particular, have a semi-circular cross-section. The commutation surface may, in particular, form a curved section of the support element.

[0034] The support element may also have a tapered section for conveying the section to the second wall. The tapered section may, in particular, be directly adjacent to the commutation surface and may be used such that the reinforcing fibers are specifically guided from their maximum expansion on the commutation surface for a particularly narrow penetration through the second wall. At its next position to the wall, the tapered section may, in particular, have a pointed tip or a minimum width in cross-section.

[0035] The reinforcing fibers can be tensioned, particularly after the introduction of the support element, by pulling and tensioning them in the second section. This tensioning of the support element and the connection between the walls prepares the connection for future force absorption. The pulling in the second section can be used, particularly in the next tufting process, to form the next connection.

[0036] The second section can form the first section, particularly when forming the next connection. In other words, the connection is first formed by tufting, wherein typically the first section is secured and then the second section is guided. This second section is now applicable as the first section for subsequent tufting processes or is incorporated into such a first section, forming another connection in the subsequent tufting process.

[0037] Between the two connecting portions of the reinforcing fibers, an additional support element may be introduced, which rests against the outer side of the first wall and reverses the direction of one or more reinforcing fibers. Specifically, this additional support element can reverse the direction of all reinforcing fibers. This allows for the defined reversal of the reinforcing fibers, as on the other side, and forces can be introduced from the wall into the respective reinforcing fibers.

[0038] The other support element may, in particular, have a flat abutment surface for abutting against the first wall. Force can be advantageously introduced into the other support element, which then transmits the force to the reinforcing fibers. The other support element may also have a reversing surface for bending the reinforcing fibers. The other support element may, in particular, reverse all reinforcing fibers and may be positioned between the connecting portions of two sequences.

[0039] The support element can be made of a metallic material, which has proven advantageous for typical use. However, other materials, such as plastics, may also be used.

[0040] Support elements can be located, in particular, outside the wall.

[0041] According to one embodiment, during the method, the core may be contained within the wall, and the core is subsequently removed. This corresponds to a core-removal process. For this purpose, the core may be made of a material that can be flushed, blown out, or sucked out. The core may be made of, for example, wax, thermoplastic, or a soluble, especially water-soluble or acid / alkali-soluble material. Core removal can be carried out, particularly after all the reinforcing fibers have been introduced.

[0042] In one embodiment, during the method, the core may be embedded in the wall, and the core remains embedded in the wall in the manufactured pressure vessel. That is, the core is not removed but is retained in the pressure vessel after it has been manufactured. The core may serve, for example, as a liner in the manufactured pressure vessel, i.e., preventing the permeation of stored gas.

[0043] The core may be subjected to pressure, for example, during or in parts of the method. To this end, the pressure, such as air pressure, within the internal space of the core can be increased. This can improve stability.

[0044] The connecting portions can, in particular, be spaced at a maximum distance of 5 mm from each other. This has proven advantageous for typical embodiments in order to ideally introduce the generated forces into the reinforcing fibers and to support the walls against each other. However, larger distances can also be used in principle. These distances can be measured, in particular, along a sequence and / or transversely to the directly adjacent connecting portions along the reinforcing fibers.

[0045] The technology disclosed herein also relates to a method for manufacturing a pressure vessel, the method comprising:

[0046] - Provide the wall structure;

[0047] - By means of the methods disclosed herein, connections are formed between the walls of the wall; and

[0048] - Apply a matrix material that surrounds the wall.

[0049] This allows for the particularly efficient manufacture of pressure vessels, including internally constructed connections for supporting walls. All the embodiments described herein can be used for the methods of constructing the connections.

[0050] In particular, the step of introducing a liner material may be set in addition, which is particularly attached to the inner wall, seals the container and / or acts as a permeation barrier for hydrogen.

[0051] The matrix, or more precisely, the matrix material, can be made, in particular, of epoxides or cast polyamides. The matrix is ​​particularly used for stabilizing and protecting the walls of pressure vessels. Especially when a gasket is not used, the matrix can also be used, according to embodiments, for gas tightness. Especially when a thermoplastic matrix is ​​used, it can be specified that the gasket, if present, is made of the same material as the matrix. This allows for a material-locking connection between the gasket and the outer wall.

[0052] Preferably, the end regions of one or more reinforcing fibers can be secured to the matrix material. This may particularly refer to regions or sections directly adjacent to free longitudinal ends. For securing, the reinforcing fibers can be embedded or secured using special fastening mechanisms. The reinforcing fibers can also be fixed by force-locking, form-locking, or material-locking. For example, two ends can be joined together, forming a force-locking connection, or the ends can be glued to the matrix material of the outer wall, forming a material-locking connection. The securing ensures that the reinforcing fibers do not break at their end locations.

[0053] The edges of the walls can be rounded, in particular. This allows for good pressure distribution at the edges. The walls forming the connection between them can be made parallel to each other, in particular.

[0054] The corners of the wall can also be rounded. For example, this can be done by wrapping with lining, such as fiber patches.

[0055] For example, when the corners of a wall or pressure vessel are not or only limited to being formed by additional winding layers, additional elements may be used at the corners, such as linings made of fiber composite layers, especially between the wound fibers or fiber composite layers, or linings made of metal, especially in the corner or corner region between the fibers or fiber composite layers and the liner.

[0056] The wall surrounded by the matrix material can, in particular, form the outer wall of the manufactured pressure vessel. Regarding the outer wall, fiber-reinforced materials can then be discussed.

[0057] The technology disclosed herein also relates to a pressure vessel manufactured by means of the methods disclosed herein according to one or more possible embodiments.

[0058] Pressure vessels manufactured according to the methods disclosed herein can be used, in particular, in motor vehicles (e.g., passenger cars, motorcycles, commercial vehicles). These pressure vessels are especially intended for storing gaseous fuels under ambient conditions. The pressure vessels can be used, for example, in motor vehicles that operate with compressed (also known as compressed natural gas or CNG) or liquefied (also known as liquefied natural gas or LNG) natural gas or hydrogen. The pressure vessels are typically fluidly connected to at least one energy converter designed to convert the chemical energy of the fuel into other forms of energy.

[0059] The pressure vessel can be implemented, in particular, as a composite material pressure vessel. The pressure vessel can be, for example, a cryogenic pressure vessel or a high-pressure gas vessel.

[0060] High-pressure gas containers are configured for storing fuel at a nominal operating pressure (also known as nominal working pressure or NWP) of at least 350 bar (= overpressure relative to atmospheric pressure) or at least 700 bar at ambient temperature. Low-temperature pressure containers are suitable for storing fuel at the aforementioned operating pressures, also at temperatures significantly lower than the operating temperature of the motor vehicle.

[0061] Pressure vessels can have a gasket, as already mentioned. The gasket forms a hollow body in which fuel is stored. The gasket can be made, for example, of aluminum or steel or their alloys. Preferably, the gasket can be made of plastic. Gasketless pressure vessels can also be provided.

[0062] The fabricated pressure vessel may, in particular, have a fiber-reinforced layer. The fiber-reinforced layer may at least partially, preferably completely, surround the gasket. The fiber-reinforced layer is often also referred to as a laminate, cladding, or liner. As the fiber-reinforced layer, fiber-reinforced plastics, such as carbon fiber-reinforced plastics and / or glass fiber-reinforced plastics, are typically used. The fiber-reinforced layer suitably has reinforcing fibers embedded in a plastic matrix. In particular, the matrix material, the type and proportion of reinforcing fibers, and their orientation can be varied to adjust the desired mechanical and / or chemical properties. The fiber-reinforced layer typically has multiple layers. The fiber-reinforced layer can, in particular, be constructed in the manner described above, whereby the fibers are formed in the form of a wall and then the matrix material is applied. Here, the outer wall of the pressure vessel can be formed.

[0063] In particular, valves can be introduced into the pressure vessel, which can be used for filling and / or for removal. Multiple valves can also be introduced. Lost cores can also be removed, for example, through such valves.

[0064] Generally speaking, to reduce the cost of future fuel cell vehicles (FCEVs), manufacturers are attempting to design a common vehicle structure for both battery electric vehicles (BEVs) and fuel cell vehicles (FCEVs). This specifically means utilizing identical or at least very similar structural spaces for integrating drivetrain components for different drive variants. Considering the accumulator, in today's BEVs, high-voltage batteries are mostly integrated into the vehicle chassis in a flat, roughly rectangular parallelepiped-shaped structural space. To utilize the same vehicle structure for both BEVs and FCEVs, this means that the currently conventional cylindrical hydrogen pressure vessels, made of carbon fiber reinforced plastic (CFK) with large diameters, must be geometrically adapted so that they can be integrated into the structural space where the high-voltage battery is located. To meet customer requirements regarding vehicle range per tank load, the existing rectangular parallelepiped-shaped structural space should be utilized as efficiently as possible for storing gaseous hydrogen or other fuels in the pressure vessel. Pressure vessels with rectangular cross-sections, featuring internal tie rods, constitute a particularly efficient solution. The tie rod, also known as the connecting part, ensures that the surfaces of the opposing planes maintain their planar shape and do not bulge under high internal pressure loads.

[0065] An exemplary external geometry for a pressure vessel used to store gaseous fuel up to, for example, a nominal working pressure of 70 MPa can be derived, for example, from a right parallelepiped whose edges and corners are rounded on the small side faces.

[0066] Large, opposing surfaces (upper and lower) are, for example, not rounded and parallel to each other. The outer wall of the pressure vessel is, for example, made of wound carbon fiber layers. Planar areas of the outer wall can be held together by tie rods or connectors to prevent deformation due to internal pressure. Aromatic polyamides and carbon fibers are particularly considered as materials for the tie rods. To transfer force from the tie rods to the vessel wall, support elements can be used, which serve both for reversing the tie rods and for the planar transfer of force from the tie rods to the vessel wall. In cross-section, the support elements are, for example, semi-circular. The support elements are preferably provided in such a way that they can absorb large pressures, preferably using metallic materials. Thus, for example, forces caused by internal pressure loads are absorbed through the tie rods in the z-direction and through the outer wall in the x and y directions. A gasket can be abutted against the inner side of the outer wall of the pressure vessel, which prevents or reduces the permeation of hydrogen or other gases through the pressure vessel wall if the outer wall impregnated with a matrix material does not meet the permeation requirements. Epoxides or cast polyamides are considered as matrix materials for the outer wall, for example. For thermoplastic substrates, it is suitable that the gasket is made of the same material so as to achieve a material-locking connection between the gasket and the outer wall. However, different materials can also be used. Additionally, a valve is preferably added to the pressure vessel, which allows for the filling and removal of hydrogen or other gases.

[0067] If the corners of the pressure vessel are not or only defined by additional winding layers, then additional elements are preferably introduced at these locations. Elements such as the following can be used here:

[0068] - A lining made of fiber composite layers, which is particularly disposed between the wound fiber composite layers in the corner areas.

[0069] - A lining made of metal, which is applied, especially in the corner areas, between the fiber composite layer and the padding.

[0070] To connect the pull strip, also referred to herein as the connecting part or reinforcing fiber, two exemplary reversing variations are distinguished in principle on the wall. The first variation shows a ring formed by two needle-punched portions. The ring is formed by two guide passages that penetrate the fiber layer and optionally a pad. The ring rests taut on a support element having a semi-circular cross-section. The second variation specifies that, to form the ring, only one guide passage guides through the fiber layer and optionally a pad. This guide passage is preferably created through a puncture with a sewing needle or tufting needle. The semi-circular support element is additionally equipped below by a second support element that provides sufficient height for forming the ring and thus ensures better guidance of the pull strip to the penetration hole in the outer wall. This avoids damage to the pull strip through the possibly sharp edges of the reversing element.

[0071] The following requirements are made for the support elements:

[0072] - The direction of the tension bar is reversed to prevent shrinkage into the outer wall.

[0073] - The tension of the tension bar is introduced into the planar force within the outer wall.

[0074] - Contribution to maintaining the distance of the pull strip.

[0075] A distance greater than 5 mm between the tie rods is unsuitable for some implementations because excessive force on each tie rod would be transmitted to the outer wall. This would result in high shear loads on the outer wall. Since the outer wall is, for example, made of a laminate composed of different fiber windings, it is not suitable for absorbing high shear loads. Therefore, a tie rod distance of, for example, less than 5 mm is preferred. However, larger distances are possible in other implementations.

[0076] To manufacture the tank or pressure vessel, a wall for the outer wall is constructed in the first step, for example. Since the wall is produced, for example, by fiber winding, a winding core is needed to depict the inner contour of the outer shell. Two manufacturing methods, essentially distinguished by the selection of the winding core, will then be described. The installation of the tie rod will then be described separately.

[0077] Manufacturing method A – using a core made of a soluble / fusible material.

[0078] Core variant A features a wound core, which is only required for the manufacturing process of the pressure vessel and is additionally removed. The wound core can be rotated in its clamping device for different winding directions. The core can be manufactured, for example, by a casting process or 3D printing. Materials such as wax or thermoplastics with low melting points are considered, which can be remelted by minor heating in subsequent processes. Also suitable are soluble materials, such as water-soluble or acid / alkali-soluble materials, such as sand cores or (water)soluble synthetic materials. The geometry of the core, on one hand, depicts the inner contour of the outer shell. Similarly, the core advantageously has a hole pattern for constructing the tie rod. The cross-section of the holes can be adapted to the geometry of the tools needed to apply the tie rod, for example, circular or quadrilateral. Similarly, the hole pattern can serve as a mold guide. After the tie rod is installed (explained separately in detail), the wound fibers depicting the outer shell of the pressure vessel, and optionally the fibers forming the tie rod, are impregnated. This can be done, for example, in a resin transfer molding process via vacuum infiltration or pressure-assisted injection. Using pre-impregnated fibers is another possibility. Epoxy resins and thermoplastics are considered as matrix materials, for example. The core accordingly prevents the filling of the subsequent pressure vessel's effective volume with resin.

[0079] After the matrix material has been introduced, the core can be removed via a filling and removal valve. The removal of the core material can be accelerated, for example, by guiding air into the interior of the pressure vessel via a bypass. Depending on whether the connection between the outer wall and the tie rod to the outer wall meets the desired sealing and permeability requirements, the liner can be introduced retroactively, for example, by a method similar to centrifugal casting. Cast polyamide is considered a preferred material for the liner.

[0080] Manufacturing method B – Core, which is retained in the component after winding and simultaneously serves as a pad.

[0081] Core variant B features a wound core that not only assists in the manufacturing process of the pressure vessel but also functions as a liner within the subsequent pressure vessel. The upper and lower sides of the core are connected by a tubular cavity through which a tie rod extends. 3D printing is preferably used as the manufacturing method for the core. A polymer material, and if possible, a thermoplastic, is preferred as the liner material. If the matrix material of the outer shell is also a thermoplastic, the same material is selected for the core, thereby achieving a material-locking connection between the outer shell and the core. The application of the winding layer, the installation of the tie rod or connector, and the impregnation of the fibers are performed similarly to manufacturing method A. To impregnate the fibers, the wound core can be additionally filled with a pressure medium via a fill and remove valve to maintain its shape stability if the matrix material is subjected to overpressure.

[0082] The tufting process used to apply the tension strips.

[0083] The tension strips, or connecting parts, of the pressure vessel are formed, for example, from high-strength fibers, preferably aromatic polyamides or carbon fibers. One fiber strip is advantageously used for multiple tension strips, wherein the fiber strip is reversed outside the outer wall. Correspondingly, the tension strips are introduced based on a stitching or tufting process.

[0084] To allow the tufting process to be performed simultaneously with multiple needles, the tufting needles are, for example, secured to a track or retaining device. As the track moves in the negative z-direction, all needles are first guided through the fiber layer on the upper outer wall, then through the hole pattern in the core, and subsequently through the fiber layer on the lower outer wall. Upon needle retraction, a loop, typical for the tufting process, is formed. This is achieved, for example, by having corresponding grooves in which the fibers run and are clamped on one side upon retraction. Based on the annular channel created by the numerous needles used, a support element can be pushed through the annular channel on the lower side. The needle is now completely pulled out of the fiber layer, and the support element is now pulled to the lower outer wall by means of a fiber clamping system. The fiber clamping system includes a fiber guiding device in which the individual fibers of the tufting needle can be pulled through or locked relatively easily according to the location of the clamping rod. Upon insertion into the tufting needle, the fibers can thus easily slide backward, and upon needle retraction, the loop is tightened by the locking clamping system. The tufting needles are then removed from the winding core again along the positive z-direction, and the fibers are tightened to ensure the reversing element is fixed on the lower side. The winding body then moves along the negative y-direction, and another support element can be inserted to revers the tensioned fibers. By repeating this process, another reversing section is created on the upper side. It is worth noting that multiple tufting operations can be performed in parallel (especially along the x-direction), so that the entire tufting process for producing the pressure vessel reflects a continuous process, continuously undergoing rhythmic feeding along the negative y-direction. Correspondingly, the implementation schemes for the annular reversing sections on the upper and lower sides differ, particularly during the tufting process. Attached Figure Description

[0085] The technology disclosed herein will now be explained with the aid of the accompanying drawings. In the drawings:

[0086] Figure 1 A portion of the pressure vessel is shown;

[0087] Figure 2 This illustrates the first type of commutator;

[0088] Figure 3 This illustrates the second type of commutator;

[0089] Figure 4 The core is shown;

[0090] Figure 5 This shows another type of core;

[0091] Figure 6 Showing tufted needles,

[0092] Figure 7 The condition during the manufacture of the pressure vessel is shown; and

[0093] Figure 8 This illustrates the combined function of the connecting part and the reversing part. Detailed Implementation

[0094] Figure 1 A portion of the pressure vessel 10 is shown schematically, wherein the pressure vessel is not yet fully constructed and is further cut open so that the components inside the pressure vessel 10 can also be seen.

[0095] exist Figure 1 The diagram also shows a typical coordinate system for such a pressure vessel 10, where the x-direction, y-direction, and z-direction are shown. The x-direction and y-direction typically form a plane, which can be horizontal, for example, in a typical installation configuration in a motor vehicle. Such a plane can be parallel to the floor of the motor vehicle, for example. The z-axis is typically vertical. However, it should be noted that the pressure vessel 10 can also be installed entirely differently in a motor vehicle or in another unit, especially completely independently of any possible orientation during the manufacture of the pressure vessel 10.

[0096] Pressure vessel 10 has a wall 20. The wall 20 surrounds the pressure vessel on the outside. The wall is composed of wound fibers, which... Figure 1 Not shown in the diagram. If a matrix is ​​subsequently applied to the wall 20, a fiber-reinforced layer is formed, which can form the outer wall of the pressure vessel 10 in its manufactured state.

[0097] The wall 20 specifically has a first wall 21 and a second wall 22. Viewed along the z-direction, the first wall 21 is disposed on the upper side and the second wall 22 is disposed on the lower side. The walls 21 and 22 are parallel to each other and, in particular, are flat. This, in principle, results in the gas stored in the pressure vessel 10 under pressure exerting a higher pressure on the first wall 21 and the second wall 22 compared to a circular wall. This can theoretically be compensated for by a higher wall thickness; however, this is often undesirable.

[0098] To compensate for the high pressure, a plurality of connecting portions 23 made of reinforcing fibers are provided in the pressure vessel 10, extending between the first wall 21 and the second wall 22 as shown. These connecting portions extend laterally to the first wall 21 and the second wall 22. The connecting portions thus connect the two walls 21, 22 to each other at many locations, thereby supporting the first wall 21 and the second wall 22 against each other. This results in the first and second walls being able to absorb high pressure and avoid damage to the wall body 20 even with significantly smaller wall thicknesses than required in other cases.

[0099] The connecting portions 23 are arranged along a plurality of sequences R as shown. The connecting portions 23 of a corresponding sequence R extend parallel to each other and are arranged side-by-side along a path. This enables particularly efficient manufacturing, which will be explained in more detail below. The connecting portions 23 are composed of a plurality of continuous reinforcing fibers, wherein each reinforcing fiber constitutes a connecting portion of a plurality of sequences R. Each reinforcing fiber extends in principle along the y-direction, i.e., it constitutes a plurality of connecting portions 23 arranged successively along the y-direction.

[0100] Not only on the upper side but also on the lower side, the corresponding reinforcing fibers are reversed in a suitable manner so that they can be easily manufactured and can preferably absorb force and introduce said force into the connection 23. (Refer to...) Figure 2 and 3 This is an explanation.

[0101] Figure 2 The reversing section is shown, which can be used, particularly on the lower side, of the second wall 22. Reinforcing fibers 30 are also visible here, which first penetrate through the second wall 22 and are then reversed by the support element 40. The support element 40 has a curved reversing surface 41 and a further tapering section 42. The support element 40 has a constant cross-section and extends along the x-direction. Therefore, in cross-section, the support element 40 is generally teardrop-shaped.

[0102] exist Figure 2 In the commutation section shown, the reinforcing fiber 30 is divided into a first segment 31 and a second segment 32. The boundary between the two segments 31 and 32 extends at the location furthest from the second wall 22, that is, at the deepest point of the curved commutation surface 41. An additional support 43 is also provided laterally to the ring thus constructed, which provides lateral stability to the reinforcing fiber 30.

[0103] exist Figure 2 In the middle, above the support element 40, the two sections 31 and 32 converge at a distance, so that they together form the connecting part 23. The connecting part is therefore no longer formed separately.

[0104] A liner 25, schematically shown, is also formed on the inner side of the second wall 22, which is used to prevent gas diffusion.

[0105] Figure 3 The reversing section is shown, as it is typically located on the upper side, i.e. above the first wall 21. Here, the reversing reinforcing fibers 30 are visible, divided into a first segment 31 and a second segment 32. It should be noted that the naming of such segments here depends on their location and, in particular, can vary during the manufacturing process, as will be explained in more detail below.

[0106] To enhance the commutation of fiber 30, another support element 45 is provided. This other support element 45 has a semi-circular cross-section and extends along the x-direction, wherein a corresponding other support element 45 is provided for each sequence R. As shown, this other support element 45 has another curved commutation surface 46 and a flat abutment surface 47 in its cross-section, the commutation surface being implemented in a semi-circular manner. Using the flat abutment surface 47, the other support element abuts against the first wall 21. The other curved commutation surface 46, in contrast, is used to enhance the commutation of fiber 30 along the semi-circle.

[0107] As shown, the reinforcing fiber 30 penetrates through the first wall 31 not only to the left of the other support element 45 but also to its right. A pad 25, schematically shown, is also formed on the inner side of the first wall 21 to prevent gas diffusion.

[0108] In the illustrated embodiment, the force applied from the inside to the first wall 21 is ideally also introduced into the reinforcing fiber 30, the force being generated by the high internal pressure within the pressure vessel 10. The reinforcing fiber 30 is thus able to achieve mutual support between the two walls 21, 22, provided that the reinforcing fiber is connected to the second wall 22 in a similar manner on the other side.

[0109] exist Figure 3 In the illustrated embodiment of the reversing section, typically the second section 32 belongs to the connecting section 23 and the first section 31 belongs to another connecting section 23, which may be at a distance of, for example, 5 mm from the first-mentioned connecting section 23, or another distance. The other support element 45 may be used, for example, for the corresponding distance.

[0110] Figure 4 One possible embodiment of the core is shown, which can be used in the manufacture of pressure vessels. The core 100 here at least generally has the shape that the pressure vessel 10 should have in its final configuration. In particular, the fibers can be wound around the core 100, wherein the core 100 is predetermined to have this shape.

[0111] The core 100 generally has four protruding corners 110, which facilitate the formation of the corners in the xy plane. Furthermore, the core has a plurality of channels 120 extending along the z-direction. The channels 120 define the position and orientation when forming the connecting portion 23.

[0112] exist Figure 4The implementation scheme relates to a core 100 as a core-free component. This means that the core is made of a material that, while used for the required stability during the manufacturing process, can then be blown out or sucked out, so that the core 100 is no longer present in the final pressure vessel 10. After the core 100 is sucked out, a liner can be formed, for example, in such a way that the material provided for this purpose is introduced into the pressure vessel 10 and the pressure vessel 10 is then moved in a suitable manner, thereby wetting the entire inner surface of the liner.

[0113] Figure 5 The core 200 is shown, which is opposite to Figure 4 The core is not considered a lost core component. This means that the core 200 is also retained in the manufactured pressure vessel 10 after the manufacturing process. The core can here in particular function as a liner, i.e., it can be made of a material that prevents gases, such as hydrogen, from permeating out of the pressure vessel 10.

[0114] The core 200 also has a plurality of channels 220 that define the position and orientation of the connection 23. The channels 220 are respectively tubular as shown here, so that in the manufactured pressure vessel 10, the connection 23 is surrounded toward the interior space of the pressure vessel 10.

[0115] Figure 6 The diagram schematically illustrates how a tufting needle 300 can be used in the tufting process described below to manufacture a pressure vessel 10. The tufting needle 300 extends longitudinally as shown and has a tip 310 at one longitudinal end. An eyelet 320 is formed adjacent to the tip 310 by the tufting needle 300. Using the eyelet 320, the tufting needle 300 can grasp the reinforcing fiber 30, through which the reinforcing fiber 30 can pass. Typically, the eyelet 320 or the tufting needle 300 divides the reinforcing fiber 30 into a first segment 31 and a second segment 32. The location where the tip 310 grasps the reinforcing fiber 30 is typically referred to as the grasping point of the reinforcing fiber 30.

[0116] Figure 7 This illustrates a typical state during the manufacture of pressure vessel 10. A wall 20 has been constructed therein, comprising a plurality of fibers, said fibers according to... Figure 4 The implementation scheme is wound around the core 100. Now, numerous reinforcing fibers 30 penetrate parallel through the wall 20, together with its first wall 21 and its second wall 22, to form a configuration already referenced. Figure 1 The described connecting part 23.

[0117] The reinforcing fiber 30 is conveyed and processed in parallel here. For conveying, there is a device (not shown), which may, for example, have a corresponding coil from which the reinforcing fiber 30 can be unwound.

[0118] There are multiple tufting needles 300, with one tufting needle 300 for each reinforcing fiber 30. The tufting needles 300 are arranged on a common holding device 350, which is movable and thereby causes all the tufting needles 300 to move parallel and simultaneously together. It is sufficient that the holding device 350 is moved and guided in a suitable manner so that all the tufting needles 300 perform the same process simultaneously. This enables a very efficient process.

[0119] The tip 310 or eyelet 320 of the tufting needle 300 divides each reinforcing fiber 30 into a first segment 31 and a second segment 32, through which the reinforcing fiber 30 passes. The first segment 31 extends to the left as shown, and the second segment 32 extends to the right as shown. In principle, the reinforcing fiber 30 is grasped by the tufting needle 300 on the first wall 21 before forming a series of connecting portions 23, in such a way that the reinforcing fiber 30 passes through the eyelet 320. The tufting needle 300 then moves vertically downward, thereby first penetrating the first wall 21 and then penetrating the second wall 22. Thus, the corresponding reinforcing fiber 30 is also guided through these walls 21, 22, i.e., the reinforcing fiber extension now passes through the automatically formed holes in the walls 21, 22 at the corresponding positions. On the underside, the reinforcing fiber 30 extends from the second wall 22.

[0120] By pulling back the tufting needle 300, its tip 310 remains below the second wall 22, forming a ring 35, which is located below the second wall 22. (See reference...) Figure 3 The support element 40 can now be pushed through the ring 35, and more precisely, pushed through such that all the rings 35 formed along a sequence R are passed through the support element 40, which are also referred to as annular channels in general.

[0121] The tufting needle 300 can then move upward again, so that the tufting needle is once again positioned above the two walls 21, 22, i.e., no longer penetrating the two walls. However, at this time the reinforcing fiber 30 is not pulled along with it, i.e., the reinforcing fiber is retained below the second wall 22 with its loop 35, because it is held in this position by the introduced support element 40. The reinforcing fiber 30 extends through the eyelet 320 when pulled back. In this position, it is now according to Figure 2 The implementation scheme constitutes a reversing section. The reinforcing fiber 30 can be pre-tensioned using a tensioning device (not shown) according to a possible method, in order to tighten the ring 35 formed on the lower side. Alternatively, this can also be done within the scope of the next connecting section.

[0122] Following the process described above, the reinforcing fiber 30 extends to the right with its second segment 32. This can be especially followed subsequently... Figure 3 One embodiment places another support element 45 below the second section 32, wherein the other support element typically also extends through all the reinforcing fibers 30 and is oriented parallel to the already mentioned support element 45 on the underside.

[0123] The tufting process can then be restarted, and more precisely, staggered in particular along the y-direction. For this purpose, the tufting needle 300 can be moved, for example, along the y-direction by a predetermined amount on its holding device 350, wherein the distance between the sequences R is adjusted in this manner. The reinforcing fiber 30 is retained in the eyelet 320, wherein the corresponding second segment 32 of the reinforcing fiber 30 becomes a new first segment 31 for forming the next connecting portion 23.

[0124] When the next connecting section 23 is formed, the reinforcing fiber 30 is again pulled downward by the tufting needle 300, wherein the previous connecting section 23 is tightened. A certain stress is particularly considered here for the reinforcing fiber 30 to adhere to the support element 40. Similarly, a corresponding rounded portion is formed on the upper side of another support element 45. The reinforcing fiber 30 is pulled downward by the corresponding tufting needle 300, typically guided laterally from the second section 32, for example by rollers or another conveying device.

[0125] In this way, the connection 23 between the walls 21, 22 of the pressure vessel 10 can be constructed very efficiently, and the connection, as already mentioned, can be used to improve compressive strength. Subsequently, the wall 20, which so far only comprises fibers, can be impregnated in a matrix material or otherwise impregnated or encased in a matrix material. Pre-impregnated fibers can also be used. After corresponding hardening and, if necessary, the introduction of a gasket 25, the pressure vessel 10 is typically constructed airtight. A valve can then be introduced, for example, to enable controlled filling and removal of gas. Alternatively, the valve can also be introduced before or during the winding process, so that the valve is wound in together.

[0126] Figure 8 A typical construction of the connection portion 23 between the first wall 21 and the second wall 22, including the corresponding reversing section, is shown. As already mentioned, a support element 40, 45 is provided on the lower and upper sides respectively, the support element having been referenced Figure 2 and 3 Explanation. The reinforcing fiber 30 is reversed on the lower side on the teardrop-shaped support element 40. The reversal is also performed on the upper side on another support element 45 with a semi-circular cross-section. At the corresponding connecting portion 23, the segments 31 and 32 of the reinforcing fiber 30 are indistinguishable from each other because they are very close together. Therefore, its… Figure 8It is not shown separately in the middle. Emerging from the left, the first segment 31 first guides downwards, and the second segment 32, after changing direction on the lower side, emerges again on the upper first wall 21. This second segment 32, after changing direction via the support element 45, again guides downwards and at this point enters the first segment 31 of the next connection 23. With this embodiment, virtually any number of connections 23 can be implemented sequentially using the reinforcing fibers 30, wherein only a very small number of process steps are required, and a large number of connections 23 can be constructed in parallel and simultaneously along a sequence. This allows for a very efficient and rapid process, thereby significantly reducing the manufacturing cost for the pressure vessel 10.

[0127] For readability reasons, the expression "at least one" is simplified and partially omitted. If a feature of the technology disclosed herein is described in the singular or indefinitely (e.g., the / a pressure vessel, the / a tufted needle, etc.), then its plural form (e.g., at least one pressure vessel, at least one tufted needle, etc.) should also be disclosed.

[0128] The foregoing description of the present invention is for illustrative purposes only and is not intended to limit the scope of 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.

[0129] List of reference numerals

[0130] 10 Pressure Vessels

[0131] 20 walls

[0132] 21 First Wall

[0133] 22 Second Wall

[0134] 23 Connecting parts

[0135] 25 padding

[0136] 30 reinforced fiber

[0137] 31 First Section

[0138] 32 Second Section

[0139] 35 rings

[0140] 40 support elements

[0141] 41. Curved reversing surface

[0142] Section 42, ending at the top of the hill

[0143] 45 Another support element

[0144] 46 Another curved reversing surface

[0145] 47 square meters of backing surface

[0146] 100 cores

[0147] 110 cents

[0148] 120 channels

[0149] 200 cores

[0150] 220 channels

[0151] 300 tufts of needle

[0152] 310 tip

[0153] 320mm eyelets

[0154] 350 holding device

[0155] R sequence.

Claims

1. A method for forming a plurality of connections (23) between a plurality of walls (21, 22) of a wall (20) of a pressure vessel (10) by a single reinforcing fiber (30) or a plurality of reinforcing fibers (30), comprising method steps repeated for a connection (23) or a sequence (R) of connections (23) formed between a first wall (21) and a second wall (22) of the wall (20): - The reinforcing fiber (30) is gripped at the gripping point of each reinforcing fiber (30) by a tufting needle (300), and the first segment (31) and the second segment (32) of the reinforcing fiber (30) extend from the gripping point; - The first wall (21) is penetrated by a tufting needle (300), and then the second wall (22) is penetrated by a tufting needle (300), so that the gripping point penetrates the first wall (21) and the second wall (22), and the first segment (31) and the second segment (32) pass through the second wall (22) and the first wall (21); - A ring (35) is formed between the gripping point and the second wall (22); and - Introduce the support element (40) into the ring (35).

2. The method according to claim 1, - In this process, multiple tufted needles (300) move simultaneously.

3. The method according to claim 1 or 2, - During the process of penetrating each of the walls (21, 22) with tufted needles (300), reinforcing fibers (30) are supplied or unwound from a reserve device.

4. The method according to claim 1 or 2, - The loop (35) is formed by pulling back the tufted needles (300).

5. The method according to claim 4, - In the pull-back of forming the ring (35), the tufted needle (300) is pulled back, such that the tufted needle also penetrates the second wall (22).

6. The method according to claim 1 or 2, - In this case, only one support element (40) is introduced into all the loops (35) of a sequence (R).

7. The method according to claim 1 or 2, - wherein the support element (40) has a curved first reversing surface (41) for reversing the one or more reinforcing fibers (30) and / or a pointed section (42) for conveying the first section (31) and the second section (32) to the second wall (22).

8. The method according to claim 1 or 2, - Wherein, after the support element (40) is introduced, the reinforcing fiber (30) is tensioned by pulling on the second section (32).

9. The method according to claim 1 or 2, - Wherein, the second section (32) constitutes the first section (31) or transitions into the first section when forming the next connecting part (23).

10. The method according to claim 1 or 2, - In this embodiment, another support element (45) is introduced between the two connecting portions (23) of a reinforcing fiber (30), the other support element abutting against the outside of the first wall (21) and causing the reinforcing fiber (30) or the plurality of reinforcing fibers (30) to be reversed.

11. The method according to claim 10, - wherein the other support element (45) has a flat abutment surface (47) for abutting against the first wall (21) and / or a second curved reversing surface (46) for reversing the reinforcing fiber (30).

12. The method according to claim 1 or 2, - in, During the method, the core (100) is in the wall (20), and the core is subsequently removed, or - During the method, the core (200) is in the wall (20), and the core is retained in the wall (20) in the pressure vessel (10) made therefrom.

13. The method according to claim 1 or 2, - Wherein, each of the connecting parts (23) is at most 5 mm apart from each other.

14. A method for manufacturing a pressure vessel (10), the method comprising: - Provide wall (20). - A connection (23) is formed between the plurality of walls (21, 22) of the wall body (20) by means of the method according to any one of claims 1 to 13, and - Apply a matrix material that surrounds the wall (20).

15. The method according to claim 14, - in, The end regions of one or more reinforcing fibers (30) are secured in the matrix material.

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