Pressure tanks for gas-powered vehicles

Abstract

A pressure vessel (1) for installation in a gas-driven vehicle to store gas has a rotationally symmetrical, elongated shape that is cylindrical in the central region and closed at both ends with arched end caps. The pressure vessel has a vessel wall that surrounds a cavity (2) for storing gas, and a metal connector, so-called boss (4, 4'), on each end cap. The vessel wall includes a reinforcing layer (6) made of fiber-reinforced plastic and an internal gasket (3) for sealing. A bushing (7, 7'), a pressure ring (8, 8'), and a spring element (9, 9') connected to the boss (4, 4') are present for sealing, such that the spring element (9') is supported on the bushing (7, 7') and presses the pressure ring (8, 8') against the gasket (3), thereby pressing the gasket against the area of ​​the boss (4, 4').

Description

Technical Field

[0001] This invention relates to a pressure vessel for storing gas, installed in a gas-driven vehicle, wherein the pressure vessel has a rotationally symmetrical, elongated shape, which is cylindrical in the central region and closed at both ends with arched end caps. The pressure vessel has a vessel wall surrounding a cavity for storing gas, and a metal connector, a so-called boss, on each end cap, wherein the vessel wall comprises a reinforcing layer made of fiber-reinforced plastic and an internal gasket for sealing.

[0002] Furthermore, the present invention also relates to a method for manufacturing such a pressure vessel or a preform thereof, wherein a liner is manufactured by a blow molding process to form the vessel wall of the pressure vessel, the liner surrounding a cavity for storing gas. Background Technology

[0003] Gas-powered vehicles, for example, use gas engines or fuel cells with electric motors as propulsion systems. To store sufficient fuel, the gas (which can be hydrogen in particular) is stored under high pressure in tanks. These pressure tanks typically operate at pressures exceeding 200 bar, often reaching 600 bar, and sometimes even 700 or 800 bar. This means that the pressure tank must not only be airtight at this pressure but also possess high mechanical stability.

[0004] In the prior art, pressure tanks for gas-driven vehicles are known. These pressure tanks have walls comprising, for example, an internal liner made of thermoplastic for sealing, and a reinforcing layer made of fiber-reinforced plastic for providing mechanical stability. Preferably, the reinforcing layer is wound and implemented as a CFK layer. CFK refers to carbon fiber reinforced plastic.

[0005] The boss has a through hole and a connecting thread. A tank fitting is connected to at least one of the two bosses, enabling the filling or controlled extraction of gas from the pressure tank. On the other boss, the through hole is sealed with a closure or a separate tank fitting or safety valve is located there.

[0006] Special attention must be paid to the joints between metal fasteners, bosses, and gaskets in such pressure vessels, as exceptionally good sealing is required, even under mechanical loads, changes in internal pressure, or significant temperature fluctuations. This presents a particularly significant challenge in the case of hydrogen tanks.

[0007] A pressure vessel with the above-mentioned features is described in DE 102014009343 A1. To improve sealing, a clamping sleeve is provided between the reinforcing layer and the gasket in this document. The clamping sleeve is intended to transfer the external load acting via the boss to the reinforcing layer and thus protect the gasket from overloads that could lead to leakage.

[0008] DE 102010021667 A1 provides a sealing ring between the boss and the gasket, which shall ensure a tight seal. In DE 102016219638 A1, the sealing ring is pressed into the gap between the boss and the gasket by a locking sleeve to achieve a seal between the gasket and the boss.

[0009] However, the implementation schemes based on the prior art have drawbacks, namely, they are not well-suited to varying loads caused by temperature fluctuations or changing pressure loads, and therefore cannot ensure long-term stable sealing.

[0010] However, good and durable sealing is particularly important, especially for larger pressure tanks, such as those used for hydrogen in commercial vehicles powered by fuel cells. These tanks may have diameters up to 600 mm and lengths up to 2500 mm. Current sealing designs are insufficient. Summary of the Invention

[0011] The present invention aims to develop a pressure vessel with better sealing performance, longer service life and lower leakage, and to demonstrate a simple and reliable method for manufacturing such a pressure vessel.

[0012] This task is accomplished, in part, by means of a pressure vessel according to claim 1. Further advantageous features are mentioned in their respective dependent claims.

[0013] According to the invention, the pressure vessel according to claim 1 is characterized by having a bushing, a pressure ring, and a spring element connected to the boss for sealing, the pressure vessel being designed such that the spring element is supported on the bushing and the pressure ring presses against the gasket, thereby pressing the gasket against a region on the boss. This region is planar and preferably constructed as an annular surface.

[0014] The main advantage of embodiments according to the invention is that, due to the spring element and the two-piece embodiment with a bushing and a pressure ring, a preload can be applied to the sealing surface between the gasket and the boss for a tight seal. This sealing surface is located in the area where the gasket is pressed against the boss. Based on the preload generated in this way, sufficient sealing is always provided, for example, even under low internal pressure or when expanding due to temperature differences. Excessive compression of the gasket and thus deformation leading to leakage can also be avoided by coordinating the adjustment of the spring force.

[0015] A spring element here refers to an element that can apply sufficient elastic spring force upon compression. For example, a spring element can be implemented as a ring-shaped element made of spring steel, having so-called spring wings; in particular, the spring element can have a U-shaped or V-shaped cross-section. Alternatively, the spring element can also be formed from multiple leaf springs or helical springs arranged between a bushing and a pressure ring. Other types and shapes of springs can also be used. In particular, a spring element can be implemented as a so-called disc spring. A disc spring can have one or more spring discs. In particular, the spring strength can be adjusted by the number of disc springs arranged sequentially.

[0016] For example, elastic polymers (elastomers or cross-linked thermoplastics) can be used as additional spring materials or spring elements made of fiber-reinforced composite plastics.

[0017] Particularly advantageous is that the spring element is configured such that its direction (in which the spring force for pressing acts) forms an angle of at most + / -20° with the longitudinal axis L of the pressure vessel, and this direction is substantially parallel to the longitudinal axis L. This orientation provides the possibility of adjusting and changing the spring preload from the outside through the center hole of the boss. Furthermore, this offers advantages during assembly.

[0018] In another preferred embodiment, the surface of the pressure ring that contacts the gasket forms an angle of 70° to 110° with the longitudinal axis L, and is particularly oriented substantially perpendicular to the longitudinal axis L. This is also advantageous for assembly and adjustability.

[0019] Preferably, the bushing is arranged such that there is no surface contact between the bushing and the gasket. The compression for sealing is transmitted only through the surface of the pressure ring.

[0020] For long-term functional assurance, it is advantageous that the pressure ring and bushing together completely enclose the spring element. Therefore, the spring element is protected and held in the desired position. Furthermore, this embodiment provides easier assembly. Moreover, these advantages have had a positive impact when the gasket is produced using a blow molding process. In this sense, complete encapsulation is also considered when individual openings or gaps still exist; it does not necessarily have to be completely sealed.

[0021] Furthermore, the pressure ring is preferably configured such that the spring element fits snugly against the contour of the spring element. This, by utilizing the larger contact area between the spring element and the pressure ring, ensures that force is evenly transmitted to the sealing surface.

[0022] In a preferred variant, the bushing is fastened to the boss via a helical thread, which in particular allows for variation of the force applied to the pressure ring. Thus, the bushing may, for example, have an external thread that engages with an internal thread on the boss. By screwing the bushing into the boss to different depths, the spring between the bushing and the pressure ring can be compressed to varying degrees. Therefore, the preload can be adjusted in a targeted manner.

[0023] Alternatively, the bushing can be fastened to the boss via a clamping part. The clamping part must be designed to prevent it from loosening due to spring force.

[0024] Furthermore, the bushing may have a flange supported by a spring element, wherein the flange is arranged substantially perpendicular to the longitudinal axis L of the pressure vessel. This allows for good assemblability and good force transmission.

[0025] In an advantageous embodiment, the boss has external threads that contact the gasket. This creates a good mechanical connection between the gasket and the boss, providing good stability during the fabrication of the reinforcing layer. The reinforcing layer is typically produced by a winding process, in which high radial forces occur.

[0026] To create sufficient sealing surface between the gasket and the boss, it is advantageous for the face of the pressure ring pressed against the gasket to extend at least 20 mm, preferably at least 30 mm, in the radial direction R. An extension of up to 100 mm as an upper limit is meaningful so that excessive structural space is not required.

[0027] When the boss has a raised portion on its surface (on which the gasket is pressed against by the pressure ring), the sealing performance of the pressure tank can be further improved. This area of ​​the boss is also referred to as the sealing surface. The raised portion is preferably implemented as a concentric ring around the longitudinal axis L. When the pressure ring is pressed against the gasket by the spring element, the raised portion on the boss is pressed into the gasket on the side opposite to the pressure ring. This significantly improves the sealing performance between the gasket and the boss. This improvement is particularly effective when the internal pressure inside the pressure tank is low. Therefore, the pressure tank can be emptied to a lower pressure level without concern about leakage.

[0028] The raised portions are only a few tenths of a millimeter high, preferably between 0.3 mm and 1.5 mm, and particularly preferably between 0.5 mm and 1 mm. Therefore, although they are slightly pressed into the gasket, they do not damage the gasket, or even cause cracks. The raised portions may, for example, have a semi-circular, triangular, or similar cross-section.

[0029] Similarly, the seal can be improved by having a groove in which a sealing ring is provided, wherein the groove is arranged such that the sealing ring contacts the gasket. Additionally, the groove is located in the area of ​​the boss where the gasket is pressed against the boss by a pressure ring. Therefore, the gasket is also pressed against the sealing ring by the pressure ring. Thus, the sealing ring can compensate for small positional changes in the gasket without compromising the seal. In addition to using a sealing ring, a support ring is preferably used. Due to the internal pressure of the container and the spring preload, the gasket is pressed tightly against the support ring, ensuring that no gaps exist between them. Thus, the sealing ring is not pressed into the gap between the gasket and the boss.

[0030] In order to build up a good preload and achieve a good seal, the pressure ring can move relative to the bushing in the direction of the longitudinal axis L, so that the pressure ring can be implemented more firmly, resulting in uniform compression on the surface and thus a reliable seal.

[0031] This embodiment is further improved when the pressure ring has stops and / or the bushing has stops, which are designed such that a rigid force transmission in the direction of the longitudinal axis L can be achieved between the pressure ring and the bushing via a fully compressed spring element. Full compression is understood here as: the spring element is compressed such that a rigid force transmission is achieved via the spring element, rather than an elastic force transmission relying on spring force.

[0032] Therefore, in order to apply a greater compressive force between the gasket and the boss than that the spring element can apply, the screw joint between the boss and the bushing can be tightened so that the force is transmitted from the bushing to the pressure ring through the stop.

[0033] This is particularly advantageous when there are raised portions on the boss that should be pressed into the gasket. Therefore, a higher compressive force can be generated when the boss is assembled onto the bushing, thereby effectively pressing the raised portions into the gasket. For example, a compressive force up to 40 kN can be applied via the screw joint, while the disc spring used as the spring element has, for example, only a 5 kN restoring force. Subsequently, excessive compressive force is detrimental during the operation of the pressure vessel because the gasket material flows and is forced out from the area of ​​the pressing surface. Therefore, the spring force cannot be selected too high. The initial flow of the gasket material after assembly ensures the creation of a small gap between the stop and its respective mating surface, thus reducing the compressive force to the operating spring force value. This value is designed such that the gasket can withstand this value for a long time. Due to the increased compressive force acting during assembly, the raised portions on the boss are effectively pressed into the gasket, ensuring an improved seal.

[0034] Furthermore, the rigid force transmission between the bushing and the pressure ring can be advantageous even during blow molding, so as to keep the part in the desired position.

[0035] On the other hand, this task is also accomplished by the method according to claim 12 for manufacturing the aforementioned pressure vessel or a preform of such pressure vessel according to the invention. Further advantageous features are mentioned in the respective dependent method claims.

[0036] The method is characterized in that a bushing, pressure ring, and spring element that can be connected to the boss are arranged on a so-called blow-molded mandrel, and the bushing is made by a blow molding process such that after the bushing is made, the pressure ring and spring element are located on the inside of the bushing, wherein when the bushing is connected to the boss, the spring element can be supported on the bushing and can press the pressure ring onto the bushing, and can press the bushing onto the surface of the boss.

[0037] In the blow molding process, plastic for the gasket is extruded from a nozzle, initially forming a flexible tube. Two or more sections of a blow mold are then brought together to form a cavity for the gasket to be formed, shaped like a pressure vessel. The extruded tube is located within this cavity. Gas is blown into the tube via a so-called blow mandrel or nozzle, causing the tube to adhere to the inside of the blow mold. This results in a gasket of the desired shape. After the plastic material has cured, the gasket can be demolded. The blow mandrel is removed. Preferably, the gasket is made of a thermoplastic material, such as polyamide. The thermoplastic cures upon cooling.

[0038] By performing the method according to the invention, the bushing, pressure ring, and spring element are introduced into their desired positions within the bushing during its manufacture, so that they can subsequently be connected to the boss and perform the function according to the invention for improving the seal. The pressure ring and spring element are located on the inner side of the bushing after its manufacture, wherein, when the bushing is connected to the boss, the spring element can be supported on the bushing and can press the pressure ring against the bushing, and can press the bushing against the surface of the boss.

[0039] In particular, larger pressure vessels have bosses on both end caps. Therefore, it is especially preferable that the two end caps of the pressure vessel are respectively provided with bushings, pressure rings and spring elements of the type described above, in order to improve the seal between the gasket and the respective bosses.

[0040] In the method according to the invention, the second bushing, the second pressure ring, and the second spring element can be arranged on a support or a blow molding die, and the liner is manufactured by a blow molding process such that after the liner is made, the second pressure ring and the second spring element are also located on the inner side of the liner, wherein when the second bushing is connected to the second boss, the second spring element can be supported on the second bushing and the second pressure ring can be pressed against the liner, and the liner can be pressed against the surface of the second boss.

[0041] To create a stable connection between the boss and the gasket, each boss preferably has external threads that engage with the corresponding internal threads in the gasket. The internal threads in the gasket are preferably machined, for example, by milling, after demolding from the blow mold. This prevents the boss from cutting into the surface of the gasket and damaging it when screwed into it. Therefore, a stable connection is achieved between the boss and the gasket, which can withstand the high loads during the manufacturing of the reinforcing layer, especially during winding. Furthermore, such threads allow for precise and repeatable screwing on the gasket, ensuring that the two components are always positioned identically.

[0042] Furthermore, it is advantageous that the first boss is equipped with a left-hand thread as its external thread and the second boss is equipped with a right-hand thread as its external thread, wherein the gasket has a corresponding matching thread on each side. This allows the two boss-gasket connections to absorb higher rotational forces in their common rotational direction and thus better protect them from unscrewing during subsequent winding.

[0043] Furthermore, during blow molding, the pressure ring can move relative to the bushing in the direction of the longitudinal axis L, so that it fully compresses the spring element, thereby enabling rigid force transmission between the bushing and the pressure ring via the spring element and, in particular, via the stops on the pressure ring and / or the stops on the bushing.

[0044] In another step, the boss is connected to the gasket and bushing, wherein the connection between the boss and the bushing is achieved by screwing the boss onto the external thread of the bushing. The boss is screwed onto the bushing such that the pressure ring moves relative to the bushing in the direction of the longitudinal axis L and the pressure ring fully compresses the spring element until a rigid force transmission between the bushing and the pressure ring is achieved via the spring element and, in particular, via a stop on the pressure ring and / or a stop on the bushing. The advantages of this process in assembling the boss have been described above.

[0045] In another step of the process, a preform made of gaskets and bosses is wound around a strip made of fiber-reinforced plastic, particularly CFK (carbon fiber reinforced plastic), to form a reinforcing layer for the pressure vessel. These strips are preferably impregnated with a matching plastic resin (so-called tow prepreg), and the plastic resin is cured after winding. Attached Figure Description

[0046] Further advantageous features of the invention will be explained with reference to the accompanying drawings and embodiments. The mentioned features can be advantageously implemented not only in the illustrated combinations, but also individually combined with each other. These drawings detail:

[0047] Figure 1 A schematic diagram of a pressure vessel according to the present invention is shown;

[0048] Figure 2a A detailed cross-section of the connection between the boss and the vessel wall in an embodiment of the invention is shown;

[0049] Figure 2b A detailed cross-section of the connection between the boss and the vessel wall is shown in another embodiment of the invention;

[0050] Figure 3a , 3b 3c shows sections according to different embodiments of the invention for sealing between the boss and the vessel wall;

[0051] Figure 3d A further section according to an embodiment of the invention is shown for sealing between the boss and the gasket during operation of the pressure tank;

[0052] Figure 3e A further section according to an embodiment of the invention is shown for sealing between the boss and the gasket during assembly of the boss;

[0053] Figure 4a A section showing an arrangement for manufacturing a pressure vessel or a preform thereof according to the present invention;

[0054] Figure 4bA section of a preform for manufacturing a pressure vessel according to the invention is shown after the assembly of the boss.

[0055] Figure 5 A detailed cross-section of the connection between the boss and the vessel wall is shown in another embodiment of the invention;

[0056] Figure 6a A further section according to an embodiment of the invention is shown for sealing the boss during operation of the pressure tank;

[0057] Figure 6b A further section according to an embodiment of the invention is shown for sealing between the boss and the gasket during assembly of the boss.

[0058] The accompanying drawings will now be described in more detail. The same reference numerals denote the same or similar components or parts. Detailed Implementation

[0059] Figure 1 A pressure vessel 1 is shown, having a boss 4, 4' on each end cap. A vessel fitting 5 for filling gas and for controlled gas extraction is screwed into the boss 4. The boss 4' is sealed with a closure. Alternatively, the boss can accommodate a safety valve. The vessel wall of the pressure vessel 1 surrounds the cavity 2 and is formed by an internal gasket 3 and a reinforcing layer 6. The gasket 3 is preferably made of thermoplastic, such as polyamide, and is manufactured by blow molding according to the method of the invention. The reinforcing layer 6 is manufactured by winding a strip of fiber-reinforced plastic, preferably CFK. The pressure vessel 1 is rotationally symmetrical about its longitudinal axis L. In such a pressure vessel, special attention must be paid to the seal between the bosses 4, 4' and the gasket 3. A good seal is a difficult challenge, especially in large pressure vessels required in commercial vehicles to achieve sufficient range.

[0060] Figure 2a and Figure 2b A magnified view of section B of the pressure vessel 1 is shown, revealing an embodiment of the invention for improving sealing. Two different embodiments are illustrated in the figure.

[0061] Inside the gasket 3, i.e., in the cavity 2, there is a pressure ring 8 and a spring element 9. The spring element 9 is pre-tightened via a bushing 7 connected to the boss 4, pressing the pressure ring 8 against the gasket 3, and thus pressing the gasket 3 against the boss 4. The connection between the boss 4 and the bushing 7 is established via a screw joint 12, wherein a corresponding external thread exists on the bushing 7. The gasket 3 is pressed against the boss only by the pressure ring 8. The pressure ring 8 is movable relative to the bushing 7 and can move in the direction of the longitudinal axis L. Together they surround the spring element 9, which is thus well protected. Furthermore, this allows the components to be well assembled. For this purpose, a special tool is used, which can be inserted through the center hole of the boss 4. Figure 2a In one embodiment, the spring element 9 is implemented as a spring ring with a U-shaped cross-section. The pressure ring 8 is preferably formed on the side against which the spring element 9 rests, so that force transmission is achieved using the largest possible contact surface. In this case, the pressure ring 8 has a curved shape corresponding to the bend of the spring ring with a U-shaped cross-section.

[0062] According to Figure 2b In one embodiment, the pressure ring 8 has a flange 23 on the side facing the gasket 3. In this embodiment, the spring element 9 is constructed as a disc spring. A disc spring with two spring discs is shown in the figure; however, only one spring disc or more spring discs may be provided. The spring force can be adjusted to the desired level by varying the thickness, material, and quantity. The pressure ring 8 is preferably formed on the side against which the spring element 9 rests, enabling good force transmission. Additionally, the pressure ring 8 has a stop 22 that rests against the bushing 7 when the spring element 9 is fully compressed. And the bushing 7 has a stop 21 that rests against the pressure ring 8 when the spring element 7 is fully compressed. Thus, a rigid force transmission can be established between the pressure ring 8 and the bushing 7, which is advantageous for the assembly of the boss or during the blow molding of the gasket.

[0063] For this embodiment of the invention, spring elements different from those shown in this example may also be used.

[0064] The surface of the pressure ring 8 pressed against the gasket 3 and the surface of the gasket 3 pressed against the boss 4 are substantially perpendicular to the longitudinal axis L. Similarly, the flange of the support spring element 9 of the bushing 7 is also arranged substantially perpendicular to the longitudinal axis L. Therefore, the spring force of the spring element 9 is fully transmitted via the screw joint 12 to the sealing surface between the boss 4 and the gasket 3 through the pressure ring 8. Sufficient force transmission can always be achieved with a tilt of up to + / -20° on these surfaces. Furthermore, the tilt of the sealing surfaces helps to better vent the sealing flange during gasket manufacturing. The tilt also allows for better gas escape from the clamping area when the mold halves converge.

[0065] The area where the pressure ring 8 of the boss 4 presses the gasket 3 against the boss 4 is called the sealing surface or choke point. Due to the spring force of the spring element 9 and due to the internal gas pressure itself, a seal is achieved by pressing the gasket 3 against the boss 4, thereby choking the internal gas pressure in the pressure vessel.

[0066] The gasket 3 is fastened to the boss 4 via a thread 10. The boss has an external thread 10, and the gasket has an internal thread 10. The internal thread 10 on the gasket is machined accordingly.

[0067] In addition, there is an internal thread 11 on the boss 4, through which tank fittings, safety valves or closures can be screwed in.

[0068] In the following Figures 3a-3c Section A is shown in the figure. These figures illustrate further embodiments in which the boss member can be advantageously implemented in the area where the pad 3 is pressed against the boss member by the pressure ring 8.

[0069] In this area, instead of a smooth surface, the boss 4 has a raised portion 13 ( Figure 3a and Figure 3b In this case, the raised portion 13 is implemented as a concentric ring on the surface and is only a few tenths of a millimeter high, preferably between 0.3 mm and 1.5 mm, particularly preferably between 0.5 mm and 1 mm. The raised portion 13 is pressed into the surface of the gasket 13 and improves the sealing effect. One type of raised portion is implemented with a rounded or semi-circular cross-section, and another type is implemented with a triangular cross-section. Other shapes are also possible.

[0070] Figure 3c Another variation for improving the seal is shown. This additional variation can also be used in conjunction with a raised portion. Here, a sealing ring 15, such as an O-ring, is inserted into a groove 14 on the boss. The groove 14 is preferably located in the area of ​​the boss 4 where the gasket 3 is pressed by the pressure ring 8. However, the groove can also be located outside this area. To prevent the sealing ring 15 from being pressed into the gap between the boss 4 and the gasket 3 under greater loads, a support ring 16 can be provided. The internal gas pressure in the pressure vessel and the compression by the spring element 9 ensure that the gasket 3 is uniformly and well-sealed against the support ring 16.

[0071] Regarding segment A, in the following... Figure 3d and Figure 3e Other variations are shown in the figures. Figure 3d The diagram shows the arrangement during pressure tank operation, while... Figure 3eThe image shows the assembled boss 4, which is performed after the gasket is blow-molded.

[0072] It is shown in a magnified manner for clarity. Figure 2a The raised portion 13 is not shown in the diagram. The raised portion 13 exists on the surface of the boss 4, against which the gasket 3 is pressed by the pressure ring 8. The raised portion 13 is not to scale, as it would otherwise be invisible. In this case, the raised portion 13 is implemented in concentric rings on the surface and is only a fraction of a millimeter high, preferably between 0.3 mm and 1.5 mm, particularly preferably between 0.5 mm and 1 mm. The raised portion 13 is pressed into the surface of the gasket 13 and improves the sealing effect. For example, the raised portion can be implemented with a rounded, semi-circular, or triangular cross-section. Other shapes are also possible. In operation, such as... Figure 3a As shown, gaps exist between the stops 21 and 22 and their respective mating surfaces on the pressure rings or bushings. The compression of the gasket 3 by the pressure ring 8, and consequently the boss 4, corresponds to a spring force of, for example, on the order of 5 kN from the spring element 9. The gap width may vary slightly depending on the filling pressure and temperature.

[0073] exist Figure 3e In this configuration, there is no gap between the stops 21 and 22 and their respective mating surfaces. The boss 4 is tightened onto the bushing 7, or the bushing 7 is tightened into the boss 4, such that it contacts the stops 21 and 22, allowing the compressive force to be increased via the screw joint. Therefore, a pressure up to 40 kN can be applied to press the protrusion 13 well into the gasket 3 during assembly. Under this high pressure and during subsequent pressure testing, the gasket material flows slightly, causing the gasket 3 to be pressed out from the compression area between the boss 4 and the pressure ring 8, and the gasket 3 becomes slightly thinner in this area. This continues until gaps appear between the stops 21 and 22 and their respective mating surfaces, thereby reducing the compressive force to the level of the spring force of the spring element 9. Thus, [the pressure is reduced to -the required level]. Figure 3a The state shown.

[0074] Further variations for improving the seal are not shown. These variations can also be used in conjunction with a raised portion. Here, a sealing ring, such as an O-ring, is inserted into a groove on the boss. The groove is preferably located in the area of ​​the boss 4 where the gasket 3 is pressed by the pressure ring 8. However, the groove can also be located outside this area. To prevent the sealing ring from being pressed into the gap between the boss 4 and the gasket 3 under greater loads, a support ring can be provided. The internal gas pressure in the pressure vessel and the compression by the spring element 9 ensure that the gasket 3 is uniformly and well-sealed against the support ring.

[0075] To illustrate the method for manufacturing a pressure vessel according to the present invention, Figure 4aand Figure 4b The truncation is also shown. Figure 4a The diagram illustrates the arrangement used in manufacturing the gasket. A bushing 7, comprising a pressure ring 8 and a spring element 9, is mounted on a blow molding mandrel 17. A two-piece or multi-piece blow molding die 18, when closed, presses the gasket material onto the blow molding mandrel 17, and onto the bushing 7 and the pressure ring 8. The gasket material, preferably thermoplastic, is extruded from a nozzle beforehand as a flexible tube. If the blow molding die is closed, gas is blown in through the blow molding mandrel, which acts as a port, thereby pressing the gasket material in a blow molding manner and forming the desired shape of the gasket 3. After curing, the blow molding die is opened and the gasket 3 is demolded. The pressure ring 8 and the spring element 9 are then positioned inside the gasket 3 in the cavity 2, and the bushing 7 is arranged such that it can subsequently be connected to the boss 4. For this purpose, a portion 3a of the gasket 3 is removed to expose the external threads on the bushing 7. Additionally, the gasket 3 can be further processed. For example, threads can be cut or milled into the surface of the pad 3 for connection with the external threads on the boss.

[0076] In order to also secure the second boss to the opposing end cap of the pressure vessel according to an embodiment of the invention for sealing, a second bushing, a second pressure ring, and a second spring element can be introduced during manufacturing. For this purpose, the second bushing, the second pressure ring, and the second spring are positioned on the side of the support or blow molding die opposite to the blow molding mandrel 17, so that during the manufacture of the gasket, they are arranged internally in a similar manner to the components on the blow molding mandrel 17. The boss is then correspondingly connected to the second bushing on that side.

[0077] Based on Figure 2b or Figure 6a An embodiment of / b according to a variant of the invention is not shown, but is equally advantageous. In blow molding, the pressure ring 8 can compress the spring elements 9; 9', such that the arrangement is rigidly fixed and held in the desired position during blow molding. Figure 2b In one implementation scheme, compression of the spring element 9 causes stops 21 and 22 to abut against their respective mating surfaces on the pressure ring or bushing. According to... Figure 6a In the implementation of / b, the spring element 9' is fully compressed, thereby giving the stops 24 and 25 a rigid force transmission via the spring element 9'.

[0078] Figure 4b The diagram shows the section after the boss 4 has been tightened onto the bushing 7. By screwing, the spring element 9 is compressed, and the pressure ring 8 is pressed onto the pad 3, which in turn is pressed onto the boss 4. The resulting preload can be adjusted by the screw-in depth and by the spring stiffness of the spring element 9.

[0079] The raised portion of the boss 4 located in the sealing surface area is pressed into the surface of the gasket 3, thereby improving the sealing performance. The raised portion is implemented here as a concentric ring with a guide circle cross section.

[0080] According to (not shown) Figure 2b or Figure 6a The / b variant can also offer advantages here. As previously mentioned, in these variants, the spring elements 9, 9' can be compressed, allowing the bushing 7 and pressure ring 8 to achieve rigid force transmission without relying on the elasticity of the spring elements.

[0081] The formed gasket 3 and the two screw-on bosses 4 are preforms for further manufacturing of the pressure vessel. In a further process step, this preform is wound with a strip made of fiber-reinforced plastic to form a reinforcing layer for the vessel wall. After winding, the fiber-reinforced plastic is hardened. Preferably, CFK strip impregnated with a suitable resin is used for this purpose.

[0082] Figure 5 A section B of the pressure vessel 1 is shown in enlarged view, but this is for another embodiment of the invention for improved sealing. The pressure ring 8' and spring element 9' are located inside the gasket 3, i.e., in the cavity 2. The spring element 9' is pre-tightened via the bushing 7' connected to the boss 4, pressing the pressure ring 8' against the gasket 3, and thus pressing the gasket 3 against the boss 4. The connection between the boss 4 and the bushing 7' is established via a screw joint 12, wherein a corresponding external thread exists on the bushing 7'. The gasket 3 is pressed against the boss only via the pressure ring 8'. The pressure ring 8' is movable relative to the bushing 7' and can move in the direction of the longitudinal axis L. The pressure ring 8' is guided on the bushing 7' via its inner diameter. In this embodiment, the pressure ring 8' and the bushing 7' can be implemented very slenderly, saving structural space.

[0083] The pressure ring 8 has a flange 23 on the side facing the liner 3.

[0084] In this embodiment, the spring element 9' is constructed as a disc spring. The figure shows a disc spring with four spring discs, but it can also have only one or more spring discs. The spring force can be adjusted to the desired level depending on the thickness, material, and number of discs.

[0085] The surface of the pressure ring 8' pressed against the gasket 3 and the surface of the gasket 3 pressed against the boss 4 are substantially perpendicular to the longitudinal axis L. Similarly, the flange of the support spring element 9' of the bushing 7' is also arranged substantially perpendicular to the longitudinal axis L. Therefore, the spring force of the spring element 9' is fully transmitted via the screw joint 12 to the sealing surface between the boss 4 and the gasket 3 through the pressure ring 8. Sufficient force transmission can always be achieved by tilting these surfaces by a maximum of + / -20°. Furthermore, the tilting of the sealing surfaces helps to better vent the sealing flange during gasket manufacturing. The tilting also allows for better gas escape from the clamping area when the mold halves converge.

[0086] The area where the pressure ring 8' of the boss 4 presses the gasket 3 against the boss 4 is called the sealing surface or choke point. Due to the spring force of the spring element 9' and due to the internal gas pressure itself, a seal is achieved by pressing the gasket 3 against the boss 4, thereby choking the internal gas pressure in the pressure vessel.

[0087] Preferably, the pressure ring 8' is formed on the side against which the spring element 9' rests, so that force can be transmitted well. In particular, the stop 24 can be provided on the pressure ring against which the spring element 9' rests.

[0088] According to embodiments of the present invention, spring elements different from those shown in this example may also be used.

[0089] The gasket 3 is fastened to the boss 4 via a thread 10. The boss has an external thread 10, and the gasket has an internal thread 10. The internal thread 10 on the gasket is machined accordingly.

[0090] In addition, there is an internal thread 11 on the boss 4, through which tank fittings, safety valves or closures can be screwed in.

[0091] In the following Figure 6a and 6b The figure shows segment A'. These figures are in Figure 6a The diagram shows the arrangement of the pressure tank during operation, while... Figure 6b The image shows the assembly of boss 4, which is performed after the gasket is blow-molded. Further details are as described above. Figure 3a and Figure 3b The accompanying diagrams are similar in description.

[0092] The main difference in the variant shown here is that the bushing 7' and especially the pressure ring 8' are implemented in a slimmer and more space-saving manner. This is a significant advantage in applications requiring minimal structural space and weight.

[0093] Figure 6aAs shown, during operation, the compression between the pressure ring 8' and the gasket 3 is achieved via a spring element 9', which is supported on the flange of the bushing 7'. A gap exists between the stop 25 on the bushing and the spring element 9'. The bushing 7' is connected to the boss 4 via an external thread 12 (not fully shown). The pressure acting on the surface of the gasket 3 can be adjusted according to the number and selection of the spring discs of the spring element 9', and according to the distance between the pressure ring 8' and the bushing 7'.

[0094] exist Figure 6b In this configuration, the spring element 9' is fully compressed, thereby achieving a rigid force transmission from the bushing 7' to the pressure ring 8'. In the illustrated embodiment, this is achieved by pressing the stop 25 of the bushing against the stop 24 of the pressure ring 8' via the spring element 9'. To achieve this, the boss 4 is tightened onto the bushing 7' or the bushing 7' is tightened into the boss 4, such that the stops 24, 25 completely press the spring element 9' together and enable a rigid force transmission via the spring element 9' without elastic influence. Therefore, as previously stated, high pressure can be applied to press the protrusion 13 well into the gasket 3 during assembly. Under this high pressure and during subsequent pressure testing, the gasket material flows slightly, and the gasket 3 is pressed out from the compression area between the boss 4 and the pressure ring 8', where the gasket 3 becomes slightly thinner. This continues until a gap appears between the spring element and the stop 25, thereby reducing the compression to the level of the spring force of the spring element 9. Thus, the desired effect is achieved. Figure 6a The state shown.

[0095] Furthermore, in this embodiment, the sealing contact surface between the pressure ring 8' and the gasket 3 is inclined relative to a direction perpendicular to the longitudinal axis L. In particular, an inclination of up to 20° is advantageous. Any possible cavitation between the gasket 3 and the pressure ring 8' can be radially pressed out from the sealing surface by the inclined posture when screwed into the boss 4. This facilitates reliable assembly.

[0096] Other variations for improving the seal are not shown. These variations can also be used in conjunction with a raised portion. Here, a sealing ring, such as an O-ring, is inserted into a groove on the boss. The groove is preferably located in the area of ​​the boss 4 where the gasket 3 is pressed by the pressure ring 8. However, the groove can also be located outside this area. To prevent the sealing ring from being pressed into the gap between the boss 4 and the gasket 3 under greater loads, a support ring can be provided. The internal gas pressure in the pressure vessel and the compression by the spring element 9 ensure that the gasket 3 is uniformly and well-sealed against the support ring.

[0097] List of reference numerals

[0098] 1. Pressure tank

[0099] 2. Cavity

[0100] 3. Padding

[0101] 3a Part of the padding

[0102] 4' Boss

[0103] 5 cans of accessories

[0104] 6 Reinforcing Layers

[0105] 7' 7' bushing

[0106] 8, 8' pressure ring

[0107] 9, 9' Spring Element

[0108] 10 External threads

[0109] 11 Internal thread

[0110] 12 Helical Thread

[0111] 13. Raised section

[0112] 14 Grooves

[0113] 15 Sealing ring

[0114] 16 Support rings

[0115] 17 Blow Molded Mandrel

[0116] 18 Blow Molding Mold

[0117] 21 Stop on the bushing

[0118] 22. Stop on the pressure ring

[0119] 23. Flange on the pressure ring

[0120] 24. Stop on the pressure ring

[0121] 25 Stop on bushing

[0122] L - Longitudinal axis of the pressure tank

[0123] R represents the radial direction of the pressure tank.

Claims

1. A pressure vessel (1) for installation in a gas-driven vehicle to store gas, the pressure vessel having a rotationally symmetrical, elongated shape, the shape being cylindrical in the central region and closed at both ends with arched end caps, the pressure vessel having a vessel wall and a metal fitting, i.e., a so-called boss (4, 4'), on each end cap, the vessel wall surrounding a cavity (2) for storing gas, wherein, The vessel wall comprises a reinforcing layer (6) made of fiber-reinforced plastic and an internal gasket (3) for sealing. Its features are, A bushing (7, 7'), a pressure ring (8, 8'), and a spring element (9, 9') connected to the boss (4, 4') are provided for sealing, and are designed such that the spring element (9, 9') is supported on the bushing (7, 7') and the pressure ring (8, 8') is pressed against the pad (3), thereby pressing it against the boss (4, 4') in the region, wherein the pressure ring (8) together with the bushing (7) completely surrounds the spring element (9).

2. The pressure tank (1) according to claim 1, Its features are, The spring elements (9, 9') are configured such that the direction of the spring force acting on the spring element for pushing forms an angle of up to + / -20° with the longitudinal axis L of the pressure vessel.

3. The pressure vessel (1) according to claim 1 or 2, Its features are, The surfaces of the pressure rings (8, 8') that contact the gasket (3) form an angle of 70° to 110° with the longitudinal axis L of the pressure tank.

4. The pressure vessel (1) according to claim 1 or 2, Its features are, The spring elements (9, 9') are implemented as so-called disc springs.

5. The pressure vessel (1) according to claim 1 or 2, Its features are, The bushings (7, 7') are fastened to the bosses (4, 4') via helical threads.

6. The pressure vessel (1) according to claim 1 or 2, Its features are, The bushings (7, 7') have flanges that support the spring elements (9, 9'), wherein the flanges are arranged substantially perpendicular to the longitudinal axis L of the pressure vessel.

7. The pressure vessel (1) according to claim 1 or 2, Its features are, The boss (4, 4') has an external thread (10) that contacts the matching internal thread of the gasket (3), and the external thread is arranged concentrically with the longitudinal axis L.

8. The pressure vessel (1) according to claim 1 or 2, Its features are, The surface of the pressure ring (8, 8') pressed against the pad (3) extends at least 20 mm in the radial direction R.

9. The pressure vessel (1) according to claim 1 or 2, Its features are, The boss (4, 4') has a raised portion (13) located in the region of the boss (4, 4') in which the pad (3) is pressed against the boss by the pressure ring (8, 8').

10. The pressure vessel (1) according to claim 1 or 2, Its features are, The pressure rings (8, 8') are movable relative to the bushings (7, 7') in the direction of the longitudinal axis L of the pressure tank.

11. The pressure vessel (1) according to claim 10, Its features are, The pressure ring (8) has a stop (22) and / or the bushing (7) has a stop (21), designed such that when the spring element (9) is compressed sufficiently strongly, the force transmission between the pressure ring (8) and the bushing (7) in the direction of the longitudinal axis L can be achieved directly via the stop (22) and / or directly via the stop (21).

12. The pressure vessel (1) according to claim 10, Its features are, The pressure ring (8') has a stop (24) and / or the bushing (7') has a stop (25), designed to enable rigid force transmission between the pressure ring (8') and the bushing (7') in the direction of the longitudinal axis L via a fully compressed spring element (9').

13. The pressure vessel (1) according to claim 2, Its features are, The direction is substantially parallel to the longitudinal axis L.

14. The pressure tank (1) according to claim 3, Its features are, The surface is oriented substantially perpendicular to the longitudinal axis L.

15. The pressure vessel (1) according to claim 1 or 2, Its features are, The bushings (7, 7') are fastened to the bosses (4, 4') via helical threads, thereby allowing the spring force that pushes the pressure rings (8, 8') to be changed.

16. The pressure vessel (1) according to claim 8, Its features are, The surface of the pressure ring (8, 8') pressed against the pad (3) extends at least 30 mm in the radial direction R.

17. The pressure vessel (1) according to claim 9, Its features are, The height of the raised portion (13) is between 0.3 mm and 1.5 mm.

18. The pressure vessel (1) according to claim 9, Its features are, The height of the raised portion (13) is between 0.5 mm and 1 mm.

19. A method for manufacturing a pressure vessel (1) or a preform of such a pressure vessel according to any one of the preceding claims, in, To construct the walls of the pressure vessel (1), a gasket (3) is manufactured using a blow molding process, the gasket surrounding the cavity (2) for storing gas. Its features are, Bushings (7, 7'), pressure rings (8, 8'), and spring elements (9, 9') that can be connected to the bosses (4, 4') are arranged on a blow-molded mandrel (17). The pad (3) is manufactured by blow molding, such that the pressure rings (8, 8') and the spring elements (9, 9') are located on the inner side of the pad after the pad (3) is made. When the bushings (7, 7') are connected to the bosses (4, 4'), the spring elements (9, 9') can be supported on the bushings (7, 7') and can press the pressure rings (8, 8') onto the pad (3) and onto the surface of the bosses (4, 4').

20. The method according to claim 19, Its features are, During blow molding, the pressure ring (8) moves relative to the bushing (7) in the direction of the longitudinal axis L, such that the pressure ring compresses the spring element (9) such that the stop (21) on the bushing (7) comes into direct contact with the pressure ring (8) for force transmission and / or the stop (22) on the pressure ring (8) comes into direct contact with the bushing (7) for force transmission.

21. The method according to claim 19 or 20, Its features are, In another method step, the boss (4, 4') is connected to the gasket (3) and the bushing (7), wherein the connection between the boss (4, 4') and the bushing (7) is achieved by screwing the boss (4, 4') onto the external thread (12) of the bushing (7), and wherein the boss (4, 4') is screwed onto the bushing (7) such that the pressure ring (8) moves relative to the bushing (7) in the direction of the longitudinal axis L and the pressure ring compresses the spring element (9) until the stop (21) on the bushing (7) and the pressure ring (8) and / or the stop (22) on the pressure ring (8) and the bushing (7) directly contact each other with their respective mating surfaces on the bushing (7) or the pressure ring (8) for force transmission.

22. The method according to claim 19, Its features are, During blow molding, the pressure ring (8') moves relative to the bushing (7') in the direction of the longitudinal axis L, so that the pressure ring fully compresses the spring element (9'), thereby enabling rigid force transmission between the bushing (7') and the pressure ring (8') via the spring element (9').

23. The method according to claim 19 or 20, Its features are, In another method step, the boss (4, 4') is connected to the gasket (3) and the bushing (7'), wherein the connection between the boss (4, 4') and the bushing (7') is achieved by screwing the boss (4, 4') onto the external thread (12) of the bushing (7'), and wherein the boss (4, 4') is screwed onto the bushing (7') such that the pressure ring (8') moves relative to the bushing (7') in the direction of the longitudinal axis L and the pressure ring fully compresses the spring element (9') until a rigid force transmission between the bushing (7') and the pressure ring (8') can be achieved via the spring element (9').

24. The method according to claim 19, Its features are, During blow molding, the pressure ring (8') moves relative to the bushing (7') in the direction of the longitudinal axis L, such that the pressure ring fully compresses the spring element (9'), thereby enabling rigid force transmission between the bushing (7') and the pressure ring (8') via a stop (24) on the pressure ring and / or a stop (25) on the bushing.

25. The method according to claim 19 or 20, Its features are, In another method step, the boss (4, 4') is connected to the gasket (3) and the bushing (7'), wherein the connection between the boss (4, 4') and the bushing (7') is achieved by screwing the boss (4, 4') onto the external thread (12) of the bushing (7'), and wherein the boss (4, 4') is screwed onto the bushing (7') such that the pressure ring (8') moves relative to the bushing (7') in the direction of the longitudinal axis L and the pressure ring fully compresses the spring element (9') until the rigid force transmission between the bushing (7') and the pressure ring (8') is achieved via a stop (24) on the pressure ring and / or a stop (25) on the bushing.

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