Method for producing a polar-cap reinforcement for a pressure vessel, and pressure vessel having polar-cap reinforcement

Abstract

The invention relates to a method for producing a polar-cap reinforcement (30P) for a fibre-reinforced pressure vessel (10), having the following steps: − providing a shaping tool in the form of at least one curved, dome-shaped polar-cap region (22; 23) with a winding axis (50) which extends along the longitudinal axis of the polar-cap region (22; 23); − producing at least one polar-cap reinforcement (30P) on the shaping tool in that a preimpregnated fibre strip (60) with a thermoplastic matrix is placed on the at least one polar-cap region (22; 23) and is wound onto the polar-cap region (22; 23) as a circumferential winding with a continuous axial offset, wherein the lateral expansion B of the fibre strip (60) extends along the winding axis (50) of the shaping tool and the energy of a heat source (80) is coupled in between the supplied fibre strip (60) and a respective placement zone (61) of the fibre strip (60), as a result of which, in the region of said placement zone (61), at least the fibre strip to be placed and the already-placed fibre strip are melted together and then consolidated. The invention also relates to a pressure vessel with an inner vessel and at least one polar-cap reinforcement; and a pressure vessel with two polar-cap reinforcements as polar-cap regions which are connected to a cylindrical central part to form a pressure vessel without an inner vessel.

Description

[0001] Method for producing a pole cap reinforcement for a pressure vessel and pressure vessel with pole cap reinforcement

[0002] Description:

[0003] The invention relates to a method for producing a pole cap reinforcement for a pressure vessel, in particular a fiber-reinforced pressure vessel. The invention further relates to a pressure vessel having at least one such pole cap reinforcement made of circumferential windings and to a pressure vessel having at least one pole cap formed from the pole cap reinforcement thus produced.

[0004] Pressure vessels play an important role in the energy transition because gases such as natural gas or hydrogen must first be stored for various applications. In many cases, it is advantageous to store the gases under high pressure, as this allows a larger amount of gas to be stored in smaller volumes. This is the case, for example, for hydrogen propulsion in buses, trucks, cars, or aircraft.

[0005] To keep weight as low as possible for these mobile applications, Type 4 pressure vessels are preferably used, in particular fiber-reinforced plastic liners, with CFRP reinforcement being the preferred option. However, the high demand for lightweight pressure vessels, which are preferably made largely from fiber-reinforced composite materials, can lead to a situation where there is a lack of raw material (carbon fibers). For this reason alone, it makes sense to keep the use of fiber reinforcement as low as possible so that material consumption per stored gas volume is as low as possible. Furthermore, the vessels should be as light as possible and production costs should be kept low, which also argues for the lowest possible material consumption for fiber reinforcement.

[0006] Fiber-reinforced Type 4 pressure vessels typically consist of a cylindrical center section, with a domed pole cap on each side that seals the pressure vessel. An internal plastic liner of the appropriate shape (cylinder and pole caps on both sides) is used to seal the pressure vessel and is reinforced with an outer layer of fiber composite material. A frequently used method for reinforcing the plastic liner is the filament winding process, in which high-strength fibers are impregnated with a matrix and wound onto the rotating plastic liner.

[0007] The dimensioning of the fiber reinforcement can be roughly divided into two areas: the reinforcement of the cylindrical part of the pressure vessel and the reinforcement of the curved pole caps. In the cylindrical part of the vessel, the radial forces are twice as high as the axial forces (Kessel formula), meaning that approximately twice as many fibers must be wound in the radial direction as in the axial direction. The pole cap area is significantly more difficult to dimension due to its three-dimensional contour, as circumferential reinforcement is difficult to wind there, at least not directly and under "industrial standards," namely at high speed and high throughput.

[0008] The reason for this is that with conventional winding processes, the fibers do not adhere to the inclined surface of a pole cap and remain in place; instead, they slide down the pole cap, thus preventing the pole cap from being reinforced as designed. The current state of the art still involves creating the necessary radial reinforcement of the fiber reinforcement through numerous steep helical windings (cross windings at a specific angle to the winding axis). This requires many more windings, each with a variety of different winding angles, than would be necessary for pure radial reinforcement at 90°. This results in many axial fiber layers, even in the cylindrical part of the pressure vessel, which are actually only used in the pole cap area.

[0009] Since fiber consumption and the associated manufacturing costs are very high, especially for long containers, it is desirable to reduce fiber consumption. This is possible, for example, if the pole cap reinforcement and the necessary fibers can be used only in the pole cap area of ​​a liner. For example, various processes are known from the state of the art that enable targeted pole cap reinforcement.

[0010] It makes sense to decouple this production step—reinforcing the pole caps in the circumferential direction—from the overall winding process and perform it separately, so that the prepared plastic liner with the pole cap reinforcements can then be fed to the final winding process. For example, structures are provided on a liner to which fibers to be wound can be held, preventing them from slipping. By appropriately shaping and arranging such holding structures, the pole caps can be wound before the cylindrical region of a pressure vessel. For example, JP 2010-236614 A discloses a method for producing a composite pressure vessel in which holding structures in the form of circumferential grooves or individual knobs are formed on the pole caps of a liner. Using these holding structures, the pole caps are wound first, followed by the cylindrical region of the liner.The process is completed with a winding layer that covers both the pole caps and the cylindrical area.

[0011] For example, patent specification 10 2018 110 049 B4 also discloses a method for producing a pole cap reinforcement in the pole cap region of a pressure vessel, in which a holding device with a plurality of protruding holding elements is mounted in the region of an end section of the cylindrical central region of a liner. A pole cap reinforcement is then produced by winding fiber material around at least part of the pole cap region and the end section with the holding device, wherein the fiber material is guided around the protruding holding elements of the holding device with a reversal of direction.

[0012] Special winding devices are also known that attempt to produce exclusively circumferential windings in the pole cap area of ​​a liner. For example, patent DE 10 2015 007 047 B4 discloses a method in which the outer surface of a pole cap is defined by several shaping parts. These shaping parts are arranged one after the other on the winding axis, starting from a winding axis of the winding body and extending outward, and a gap between the winding mandrel and the previously arranged shaping part is filled with circumferential windings. The shaping parts are then removed.

[0013] Based on this, the object of the invention is to provide an alternative method for producing a pole cap reinforcement for a pressure vessel, which allows the amount of required reinforcing fibers to be reduced, with the fiber orientation running particularly in the circumferential direction. Advantageously, the pole cap reinforcement should also be usable as a pole cap itself, without an inner liner.

[0014] According to the invention, this object is achieved by a method for producing a pole cap reinforcement according to independent claim 1. Advantageous developments of the method arise from subclaims 2-9. Furthermore, the object is achieved by pressure vessels with a pole cap reinforcement produced in this way according to claims 10 and 11, wherein claim 12 specifies an embodiment of a pressure vessel according to claim 11.

[0015] It should be noted that the features listed individually in the claims can be combined with one another in any technically reasonable manner and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0016] The method according to the invention is used to produce a pole cap reinforcement for a pressure vessel, in particular a fiber-reinforced pressure vessel. A pressure vessel must be suitably reinforced axially and radially if an inner vessel / liner only performs the sealing function and represents the winding core for a winding process. The axial reinforcement of a wound Type 4 pressure vessel runs from one pole to the other and usually also encloses the so-called boss connection at both ends, thereby firmly binding it. Typical winding angles are 5-15°, as this does not result in a significant decrease in the strength values ​​of the laminate compared to a 0° laminate. Radial reinforcement is possible in the cylindrical part of the liner using standard winding processes. However, a fiber structure, referred to below as pole cap reinforcement, can also be used as the pole cap itself in a pressure vessel without an inner liner.The term “pole cap reinforcement” therefore does not necessarily imply that another component is being reinforced.

[0017] The method according to the invention for producing such a pole cap reinforcement is characterized by at least the following steps:

[0018] - Providing a molding tool in the form of at least one curved, dome-shaped polar cap region with a winding axis extending along the longitudinal axis of the polar cap region;

[0019] - Producing at least one pole cap reinforcement on the forming tool by depositing a pre-impregnated fiber band with a thermoplastic matrix on the at least one pole cap region and winding it onto the pole cap region as a circumferential winding with a continuous axial offset, wherein the lateral extent B of the fiber band extends along the winding axis of the forming tool and the energy of a heat source is coupled between the supplied fiber band and a respective deposition zone of the fiber band, whereby at least the fiber band to be deposited and the already deposited fiber band fuse together and are subsequently consolidated in the region of this deposition zone.

[0020] The invention therefore does not use a thermosetting fiber composite material, but rather a pre-impregnated fiber tape made of a fiber composite material with a thermoplastic matrix and a certain lateral extension, i.e., a width B. These are thus thermoplastically pre-impregnated tapes. They are flat and have a width B much greater than their thickness. Typically, they are unidirectionally reinforced.

[0021] Typically, a thermoplastic liner made of polyethylene (PE) or polyamide (PA) is used in the manufacture of Type 4 pressure vessels. Fiber reinforcement is then wound onto this liner using a suitable fiber winding process until the resulting laminate with the appropriate angles and layer thicknesses is achieved. If a thermosetting matrix is ​​used for the winding, a geodesic fiber layup must generally be selected, otherwise the "wet" thread will slip. If so-called towpregs, which exhibit a certain stickiness, are used, a slight deviation from the geodesic path is possible. When processing thermosetting fiber composite materials, however, it is almost impossible to produce radial reinforcement in the pole cap area using the direct "classic" winding process.

[0022] The situation is different with the inventive use of thermoplastic fiber composite material. This material can be provided as a fiber tape with a specific width and thickness. Different fiber materials are used, such as carbon fibers, glass fibers, or other fibers. Classic thermoplastics such as PP (polypropylene), PE (polyethylene), PA (polyamide), or PEEK (polyetheretherketone) plastics are used as the matrix.

[0023] These fiber ribbons are wound on spools and are dimensionally stable. They are wound lengthwise. They are preferably very stiff along their width B, i.e., in the transverse direction, and can hardly be bent. The thermoplastic material in the fiber ribbon can be melted; in this way, the fiber ribbon can be welded or bonded to a thermoplastic base, such as another fiber ribbon or an inner container made of the same or similar plastic. Depending on the melting principle and technology, a very fast and targeted connection can be created at a single point, as is possible, for example, with the laser melting process.

[0024] If this material and the joining technology are applied to the manufacture of pressure vessels, for example, a different reinforcement can be applied to a thermoplastic liner than is possible with thermosetting reinforcement materials. The only limitations are that the fiber sliver must be laid down straight and can hardly be bent laterally. Therefore, the invention provides that a fiber sliver is not laid on a pole cap area, but rather it is wound up in which the lateral extent B of the fiber sliver extends along the winding axis. The fiber sliver stands virtually upright on the pole cap area, with an axial offset of the fiber sliver occurring as the diameter of the pole cap area increases. The fiber sliver to be laid down therefore does not lie flat on the pool cap, but rather the transverse direction of the fiber sliver (lateral extent B, width) is always approximately parallel to the winding axis during the winding process.In this way, the fiber sliver to be laid down can be fused flatly with the fiber sliver already laid down, whereby a solid fiber structure can be formed which consists exclusively of an essentially radially running circumferential winding.

[0025] The thermoplastic fiber tape and the rapid melting of the matrix allow the fiber tape to be fixed in place, allowing for pole cap reinforcement of the liner with radial fiber orientation. Slippage of the fiber tape can be prevented due to the rapid cooling and associated fixation.

[0026] The method according to the invention therefore has the advantage that it can be used to produce a pole cap reinforcement or even a pole cap itself using only circumferential windings. This significantly reduces the fiber requirement for the entire pressure vessel, as unnecessary windings in the cylindrical region can be avoided. In the method according to the invention, at least one curved pole cap region is wound radially, but a circumferential winding produced in this way can also extend beyond a curved pole cap region into an adjoining cylindrical region if the mold used is designed with a corresponding cylindrical region. This is the case, for example, with an inner liner. As a result, part of a hollow cylinder is produced from the circumferential windings together with a pole cap.

[0027] During the winding process, the energy from a heat source can therefore be continuously coupled between the fed fiber sliver and a respective deposition zone of the fiber sliver, whereby in the area of ​​this deposition zone at least the fiber sliver to be deposited and the fiber sliver already deposited are fused together and then consolidated. The heat source used is in particular a laser, in particular a laser whose laser beam is distributed over the entire area of ​​the fiber sliver deposition zone by means of an optics. The laser power is easily adjustable and the positioning of a melting area or a focal spot is also very easy to carry out with a laser. The easily adjustable laser power and the positioning of the focal spot make it possible, for example, for the fed fiber sliver to be fused not only with the previously deposited fiber sliver, but also with a thermoplastic liner.This enables a firm connection between fiber reinforcement and liner.

[0028] Preferably, the fiber ribbon is wound from the smaller diameter to the larger diameter of the curved pole cap region. In this way, a winding with a progressively larger diameter can be continuously deposited onto a winding with a smaller diameter, with the required axial offset. Furthermore, it can advantageously be provided that the forming tool rotates about its winding axis while the fiber ribbon is wound from a stationary spool onto the curved pole cap region. In an alternative embodiment, the directions of movement can also be reversed, so that the forming tool remains stationary while a spool with fiber ribbon rotates about the winding axis. However, the first embodiment is preferable.

[0029] The fiber reinforcement is essentially wound radially. The fiber deposition follows the contour of the forming tool, i.e. the dome shape of the curved pole cap area, whereby the circumferential winding is carried out with a continuous axial offset. However, with increasing diameter D of the pole cap area, the radial fiber reinforcement can become increasingly smaller or thinner because, with a constant fiber ribbon width B, the axial offset per revolution becomes increasingly larger and the layer thickness becomes smaller, for example in the radial direction. This can be compensated for by using a wider fiber ribbon towards the outside. The process can be stopped at any time and restarted with a new ribbon (here with fiber width variation). In one embodiment, it is therefore provided that the lateral extent B of the fiber ribbon increases from the smaller diameter to the larger diameter of the curved pole cap area.In particular, the winding process is interrupted at least once, during which interruption a first fiber band is replaced by a second fiber band with a larger lateral extension B. Alternatively, it can be provided that already in the region of the smaller diameter a sufficiently wide fiber band is used, which then also produces a required minimum wall thickness in the radial direction in the region of a larger diameter.

[0030] The winding process begins in the area of ​​a winding cylinder located centrally on the curved pole cap area. This can be, for example, a connecting flange, a simple boss connection, or a metal cylinder. The fiber sliver is deposited and secured on this winding cylinder at the beginning of the winding process. Furthermore, it is preferably provided that at least the deposited fiber sliver is consolidated under pressure, in particular by means of a pressure roller.

[0031] Furthermore, the method for producing a pole cap reinforcement can be used in at least two ways. In a first variant, a Type 4 pressure vessel is produced in which a liner (inner vessel) is provided with an outer fiber reinforcement, wherein the method according to the invention is used to reinforce the two opposite pole cap regions. In this embodiment, the mold used is therefore an inner vessel of a pressure vessel to be produced, which is made of a thermoplastic material and has a cylindrical central region and two curved pole cap regions that close off the openings of the cylindrical central region. The pole cap reinforcement according to the invention is then carried out on both sides of the liner, either one after the other or simultaneously using a second deposition head. The cylindrical part of the liner is then reinforced until a smooth surface is formed for the pole cap reinforcements.Subsequently, the axial reinforcement of the liner is applied according to the pressure vessel design, either with thermoplastic fiber reinforcement or with thermoset fiber reinforcement. The invention thus makes it possible to reinforce a liner—preferably a thermoplastic liner—in the pole cap area with pure radial fiber layers in a separate process. The liner, then prepared with two pole cap reinforcements, is fed to the actual winding process and can then be provided with the radial windings in the cylindrical part as well as with the necessary axial windings (and optionally compressive radial windings if thermoset windings are used).

[0032] In this case, the invention therefore also encompasses a pressure vessel comprising an inner container and an outer layer of reinforcing fibers wound onto the inner container, wherein the inner container has a cylindrical central region and two curved pole cap regions that close the openings of the cylindrical central region. The outer layer of reinforcing fibers has, in at least one curved pole cap region of the inner container, a pole cap reinforcement with circumferential windings, which was produced using a method according to one embodiment of the invention.

[0033] The described process steps can also be carried out to produce a Type 5 pressure vessel. The Type 5 pressure vessel is a fiber-reinforced pressure vessel without a liner. If the pole cap reinforcement is manufactured in such a way that the fiber reinforcement does not bond to the molding tool, the reinforcement can be removed from the molding tool contour after winding. The molding tool with the contour of a liner then no longer needs to be made of thermoplastic material, but can be made of metal or similar, for example, so that the fiber band does not bond to the molding tool.

[0034] If a hollow cylindrical tubular element is also produced from the same composite material, the three elements (two fiber-reinforced pole caps and a fiber-reinforced tubular cylinder) can then be joined together, for example, by welding. An inner liner is then no longer required. The result is the inner contour of the pressure vessel without an inner liner. A component produced in this way can also be used as a forming tool for additional fiber reinforcements. Alternatively, a curved pole cap area could be radially wound into the cylindrical area of ​​a forming tool, resulting in a curved pole cap reinforcement with an adjoining hollow cylindrical area. For example, approximately half the cylinder length of a pressure vessel to be manufactured could be formed in one pole cap area. Two components produced in this way are then connected to each other via their hollow cylinders, e.g.welded together, thus forming a cylindrical container with two domed ends.

[0035] The invention therefore also encompasses an embodiment in which a molding tool is a separate component from which the pole cap reinforcement is removed after its manufacture. Thus, the invention also encompasses a pressure vessel comprising a cylindrical central region and two curved pole cap regions that close off the openings of the cylindrical central region, wherein at least one pole cap reinforcement with circumferential windings, which was manufactured using a method according to an embodiment of the invention, forms a curved pole cap region. In particular, two pole cap regions and a cylindrical central region are then connected, in particular welded, to one another to form a vessel without an inner liner.

[0036] Further advantages, special features and expedient developments of the invention emerge from the subclaims and the following representation of preferred embodiments with reference to the figures.

[0037] From the pictures shows:

[0038] Fig. 1 a pressure vessel;

[0039] Fig. 2 shows a schematic longitudinal section through a pressure vessel according to Fig. 1; Fig. 3 shows an enlarged view of a pole cap area with radial reinforcement;

[0040] Fig. 4 is a schematic view of a polar cap region with radial polar cap reinforcement according to the invention;

[0041] Fig. 5 is a schematic front view of a pole cap region at the beginning of a winding process in the circumferential direction;

[0042] Fig. 6 is a schematic front view of a pole cap region during a winding process in the circumferential direction;

[0043] Fig. 7 is a three-dimensional view of a pole cap region during a winding process in the circumferential direction;

[0044] Fig. 8 is an enlarged view of a melt zone; and

[0045] Fig. 9 is a schematic representation of a preferred embodiment of the invention.

[0046] A possible pressure vessel or composite pressure vessel to be manufactured using the method according to the invention for pole cap reinforcement is shown by way of example in Fig. 1. The pressure vessel 10 has a cylindrical central section 11 and two curved pole caps 12 and 13, which close off the openings of the cylindrical central section 11. Protruding connecting flanges 14 and 15 can be provided on these pole caps 12, 13, although the shape and arrangement of these connections 14, 15 are to be understood only schematically and as examples. Such connecting flanges are also referred to as boss connections. The cylindrical central section 11 has end sections at its ends, to which the curved pole caps 12, 13 are connected.

[0047] Such a pressure vessel 10 is manufactured, for example, by reinforcing an inner container with an outer layer of fiber reinforcement. Fig. 2 shows this structure of the pressure vessel 10 in a schematic longitudinal section. An inner container 20 is wrapped with an outer layer of reinforcing fibers, which includes radial and axial reinforcements. The shape of the inner container 20 essentially corresponds to the shape of the pressure vessel 10 to be manufactured, so that the inner container 20 has a cylindrical central region 21 and two curved pole cap regions 22 and 23, which close off the openings of the cylindrical central region 21. The inner container 20 is preferably formed by a plastic liner, the shape of which was produced, for example, using an extrusion blow molding process. In particular, the inner container 20 is a liner made of thermoplastic material, for example PE or PA.Such an inner container 20 is wound with reinforcing fibers at different angles and with different courses.

[0048] Fig. 2 shows a fiber reinforcement of a plastic liner 20, as can be advantageously implemented. This provides a radial reinforcement 30 across the entire liner 20, encompassing the cylindrical central region 21 and the two pole cap regions 22 and 23. Furthermore, an axial reinforcement 40 is provided across the entire container 10. This ideal fiber alignment in the direction of force allows the maximum laminate and fiber properties to be utilized.

[0049] Since such a radial reinforcement 30 cannot easily be wound continuously on a curved pole cap region, this radial reinforcement 30 is divided into a cylindrical reinforcement 30Z and two pole cap reinforcements 30P. The cylindrical reinforcement 30Z is located in the cylindrical region of the pressure vessel 10, while each pole cap has a pole cap reinforcement, whereby in Fig. 2 only a left pole cap reinforcement is provided with the reference number 30P as an example. Fig. 3 shows the left pole cap region 22 of a liner again in an enlarged view. The radial reinforcement 30P covers the area from the boss connection 14 to the cylindrical central region 21 of the liner and optionally extends into the cylindrical central region 21, as is the case in the embodiment of Fig. 3. For example, the two pole cap reinforcements 30P are manufactured before the cylinder reinforcement 30Z and before the axial reinforcement 40 is applied.The manufacture and use of a 30P pole cap reinforcement is described below.

[0050] Fig. 4 initially shows a schematic view of a pole cap region with radial pole cap reinforcement according to the invention. The figure shows that the pole cap reinforcement 30P extends from a winding cylinder 16 across the curved pole cap region 22. The winding cylinder 16 can be, for example, a connecting flange, a boss connection, or a metal cylinder (non-boss side). The figure also shows that the pole cap reinforcement 30P consists of several circumferential layers of a fiber ribbon with a certain lateral extension, wherein the lateral extension extends along the winding axis 50, which corresponds to the longitudinal axis of the pole cap region 22.

[0051] Fig. 5 shows a schematic front view of a pole cap region at the beginning of a winding process in the circumferential direction. The forming tool in the form of the pole cap region 22 rotates about its winding axis, while a fiber sliver 60 is wound radially. The fiber sliver 60 is first deposited on the winding cylinder 16 and fixed in place. Subsequently, a substantially radial circumferential winding of fiber sliver 60 is wound onto the pole cap region 22 with continuous axial offset. In order to fix the fiber sliver 60, the energy from a heat source is coupled into the deposition zone 61. This is done, for example, by means of a laser (see Fig. 7). As a result, a fiber sliver to be deposited is fused at least with an underlying, already deposited fiber sliver and then consolidated. This consolidation preferably takes place under pressure; in the embodiment of Fig. 5, a pressure roller 70, for example, is provided for this purpose.

[0052] Fig. 6 shows a schematic front view of a pole cap region during a winding process in the circumferential direction, wherein the winding is more advanced than in Fig. 5. It can be seen how the pole cap reinforcement 30P is forming on the pole cap region 22. Fig. 7 also shows an advanced state during the winding process. This three-dimensional view also schematically shows the coupling of the energy from a laser beam (80) in a deposition zone 61. Furthermore, it can be seen that the fiber ribbon 60 is wound up as a strip such that its lateral extent runs along the winding axis. In this way, the fiber ribbon 60 is not laterally curved during the winding process, but can be continuously applied to the pole cap region 22 with an axial offset. In this case, a fiber ribbon 60 to be applied is always fused with a fiber ribbon already applied, so that a solid fiber structure is formed.Also shown is the pressure roller 70, which presses the fiber ribbon 60 flat.

[0053] The orientation of the fiber ribbon 60 can also be seen in Fig. 8, which shows a slightly enlarged view of a melting zone. The fiber ribbon 60 to be applied has a lateral extent B, which extends along the winding axis 50. The winding process can be described as follows: A forming tool or a thermoplastic liner is clamped, for example, onto a rotary axis, and the liner rotates around the longitudinal axis 50. The fiber ribbon is wound up from the small to the large diameter. The thermoplastic fiber ribbon 60 is fixed to the cylindrical part of the boss connection or to a metal pin. The liner rotates and the thermoplastic fiber ribbon is wound up. A laser beam is coupled into the contact plane between the fed fiber ribbon and the application point, i.e., in a deposition zone.An optical system distributes the laser beam evenly over the fed fiber ribbon and the deposition zone, resulting in a surface temperature at the contact point above the melting temperature of the thermoplastic matrix. A pressure roller 70 presses the molten fiber ribbon 60 onto the likewise molten deposition point, consolidating the material.

[0054] Behind the deposition point, the material cools down quickly again because only enough energy is introduced for the material to melt at the deposition point and be bonded. The fed fiber ribbon 60 is thus firmly bonded and fixed within a very short time. Slipping is thus prevented. The fiber reinforcement is thus wound radially, with the fiber deposition following the contour of the pole cap region. Fig. 9 shows a schematic representation of a preferred embodiment of the invention. With increasing diameter D, the radial fiber reinforcement 30P becomes increasingly thinner because, with a constant fiber ribbon width, the axial offset V per revolution becomes increasingly larger and the layer thickness s becomes smaller in the radial direction. This can be compensated for by using a wider fiber ribbon towards the outside.For example, the process can be stopped at any time and restarted with a new ribbon (here with a fiber width variation). Fig. 9 therefore shows an embodiment in which the width B" in the outer region is larger at a larger diameter D than the width B' in the inner region at a smaller diameter D. This is particularly the case in the transition region from the pole cap region 22 to the cylindrical central part 11.

[0055] The winding process is continued until this cylindrical central section 11 of the liner is reached. The pole cap reinforcement is applied on both sides of the liner, either consecutively or simultaneously using a second lay-up head. The cylindrical section of the liner is then reinforced until a smooth surface is achieved with the pole cap reinforcements. Subsequently, the axial reinforcement of the liner is applied according to the pressure vessel design, either with thermoplastic fiber reinforcement or with thermoset fiber reinforcement.

[0056] However, the described pole cap reinforcement 30P can also form a pole cap itself in a Type 5 pressure vessel, with appropriate design, without the use of an inner vessel (liner). The pole cap reinforcement 30P is then removed from the mold after its manufacture. List of reference symbols:

[0057] 10 pressure vessels

[0058] 11 Middle section

[0059] 12,13 Polar cap

[0060] 14,15 Connection flange, boss connection

[0061] 16 winding cylinders

[0062] 20 inner containers, liners

[0063] 21 Middle area

[0064] 22,23 Polar cap area

[0065] 30 Radial reinforcement

[0066] 30P pole cap reinforcement

[0067] 30Z cylinder reinforcement

[0068] 40 outer winding

[0069] 50 winding axis

[0070] 60 fiber band

[0071] 61 Storage zone

[0072] 70 pressure roller

[0073] 80 Heat source, laser energy

[0074] B Width fiber band

[0075] D Diameter of polar cap area

[0076] V offset, axial

[0077] S Layer thickness pole cap reinforcement

Claims

Patent claims: 1 . A method for producing a pole cap reinforcement (30P) for a fiber-reinforced pressure vessel (10), characterized by the following steps: - Providing a molding tool in the form of at least one curved, dome-shaped pole cap region (22; 23) with a winding axis (50) extending along the longitudinal axis of the pole cap region (22; 23); - producing at least one pole cap reinforcement (30P) on the forming tool by depositing a pre-impregnated fiber band (60) with a thermoplastic matrix on the at least one pole cap region (22; 23) and winding it as a circumferential winding with a continuous axial offset onto the pole cap region (22; 23), wherein the lateral extent B of the fiber band (60) extends along the winding axis (50) of the forming tool and the energy of a heat source (80) is coupled between the supplied fiber band (60) and a respective deposition zone (61) of the fiber band (60), whereby in the region of this deposition zone (61) at least the fiber band to be deposited and the fiber band already deposited fuse together and are subsequently consolidated.

2. Method according to claim 1, characterized in that the heat source (80) is a laser, in particular a laser whose laser beam is distributed over a surface in the region of the deposition zone (61) by means of an optical system.

3. Method according to one of claims 1 and 2, characterized in that the fiber band (60) is wound from the smaller diameter to the larger diameter of the curved pole cap region (22; 23).

4. Method according to one of claims 1 to 3, characterized in that the lateral extent B of the fiber band (60) increases from the smaller diameter to the larger diameter of the curved pole cap region (22; 23).

5. Method according to claim 4, characterized in that the winding process is interrupted at least once, during which interruption a first fiber band is replaced by a second fiber band with a larger lateral extent B.

6. Method according to one of claims 1 to 5, characterized in that the at least one curved pole cap region (22; 23) of the forming tool has a central winding cylinder (16) on which the fiber band (60) is laid down and fixed at the beginning of the winding process.

7. Method according to one of claims 1 to 6, characterized in that the molding tool is an inner container (20) of a pressure vessel (10) to be produced, which is formed from a thermoplastic material and has a cylindrical central region (21) and two curved pole cap regions (22; 23) which close off the openings of the cylindrical central region (21), wherein a pole cap reinforcement (30P) according to one of claims 1 to 8 is produced on both pole cap regions (22; 23).

8. Method according to one of claims 1 to 6, characterized in that the molding tool is a separate component from which the pole cap reinforcement (30P) is removed after its manufacture.

9. Method according to one of claims 1 to 8, characterized in that a manufactured circumferential winding extends beyond a curved pole cap region (22; 23) into an adjoining cylindrical region of a forming tool.

10. Pressure vessel (10), comprising an inner container (20) and an outer layer of reinforcing fibers wound on the inner container (20), wherein the inner container (20) has a cylindrical central region (21) and two curved pole cap regions (22; 23) which close off the openings of the cylindrical central region (21), characterized in that the outer layer of reinforcing fibers in at least one curved pole cap region (22; 23) of the inner container (20) has a pole cap reinforcement (30P) with circumferential windings, which was produced by a method according to one of claims 1 to 9.

11. Pressure vessel (10) comprising a cylindrical central region (21) and two curved pole cap regions (22; 23) which close off the openings of the cylindrical central region (21), characterized in that at least one pole cap reinforcement (30P) with circumferential windings, which was produced by a method according to one of claims 1 to 9, forms a curved pole cap region (22; 23) of the pressure vessel (10).

12. Pressure vessel according to claim 11, characterized in that the two pole cap regions (22; 23) and a cylindrical central region (21) are connected, in particular welded, to one another to form a vessel without an inner liner.

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