Coupling for cryogenic conduits

Abstract

A coupling (1) for cryogenic cables is proposed, comprising a coupling socket (3) and a coupling plug (2), in which: the coupling plug (2) has a first inner, media-carrying pipe element (13) and a first outer pipe element (14) which coaxially surrounds the first inner pipe element (13) at a radial distance, between which first pipe elements (13, 14) an evacuable first free space (56) is formed; the coupling bushing (3) has a second inner pipe element (23, 29) and a second outer pipe element (24) which coaxially surrounds the second inner pipe element (23, 29) at a radial distance, between which second pipe elements (23, 24) an evacuable second free space (55) is formed; the first inner piping element (13) is detachably connected or connectable to the second inner piping element (23, 29); the first outer pipe element (14) is detachably connected or connectable to the second outer pipe element (24); characterized by a drive element (36) that is connected or connectable to the coupling plug (2) and that has a first engagement structure which is complementary to a second engagement structure on the coupling socket (3), or that b) has a first engagement structure which is complementary to a second engagement structure on the coupling plug (2); wherein, after the first engagement structure and the second engagement structure have been brought into contact, an axial relative movement of the coupling plug (2) and coupling socket (3) is caused or can be caused by a rotational movement about a common longitudinal axis (L) of the pipe elements (13, 14, 23, 24) exerted from the outside on the drive element (36), wherein a fluid-tight connection is created or can be created between the first inner pipe element (13) and the second inner pipe element (23, 29).

Description

[0001] The invention relates to a coupling for cryogenic conduits (conduits for conveying cryogenic media, such as liquid helium or hydrogen) according to the preamble of claim 1.

[0002] Such a coupling can be designed, in particular, as a plug-in coupling for cryogenic conduits and typically comprises a coupling socket and a coupling plug, wherein the coupling socket and the coupling plug each have an inner tube element and an outer tube element arranged coaxially to the inner tube element. In the connected state, the coupling plug is inserted into the coupling socket. Furthermore, in the connected state, the coupling socket and the coupling plug are detachably connected to each other by a first connection located at one end, referred to as the "hot" end, in the region of their outer tube elements. Additionally, in the connected state, a gap between the coupling socket and the coupling plug in the region of their inner tube elements is sealed by a gasket at another end, referred to as the "cold" end.The coupling socket and coupling plug are usually made of a metal, preferably (stainless) steel.

[0003] Such couplings are also known as Johnston couplings. Examples are known from DE 41 07 652 A1 or EP 3 339 713 B1. The seal against the system pressure takes place in the so-called hot part of the coupling.

[0004] Due to the thermal sealing, both so-called insulation pipes—that is, the inner pipe element of the coupling socket and the outer pipe element of the coupling plug—are exposed to (usually atmospheric) ambient pressure. This poses a particular risk of bulging for the insulation pipe of the coupling plug (hereinafter also referred to simply as "plug"), which is why, according to current technology, this component had to be dimensioned with a correspondingly robust, thick wall. This results, among other disadvantages, in increased heat input at the cold end of the coupling.

[0005] Furthermore, due to insufficient sealing at the cold end, a gap formed between the outer tube element of the plug and the inner tube element of the coupling socket (hereinafter also referred to as "socket") is regularly partially filled with cold liquid (the cryogenic medium). This creates a risk that a thermally insulating gas cushion between a sealing element at the warm end and this liquid will be overcome by the liquid, consequently cooling the sealing element. As a result, the sealing element becomes brittle, and the sealing function is no longer guaranteed.

[0006] This means that such couplings must preferably be positioned so that a normal vector of the coupling separation plane has a positive component parallel to the gravitational vector. In other words, the couplings cannot be installed completely horizontally, which correspondingly limits their application possibilities.

[0007] From DE 10 2022 110 880 A1, another connection arrangement or coupling for a cryogenic conduit with an inner conduit element and an outer conduit element is known, in which a spacer element, arranged between an inner connecting element and an outer connecting element and sealing off a free space between the two conduit elements from the environment, is designed as a grooved membrane disk and arranged in a plane extending transversely to a longitudinal axis of the conduit. This results in a relatively short axial dimension, while still providing a sufficiently long path for the incident heat to ensure good thermal insulation of the connection. However, the problem described above for Johnston couplings due to insufficient sealing at the cold end can also occur here.

[0008] The invention is based on the objective of further developing a coupling of the aforementioned type in such a way as to achieve an improved seal at the cold end. This is intended to reduce the risk of cooling to the "warm" sealing element and the heat input at the cold end of the coupling.

[0009] This problem is solved according to the invention by a coupling having the features of claim 1. Advantageous embodiments are defined in the dependent claims.

[0010] A coupling according to the invention for cryogenic conduits, comprising a coupling socket and a coupling plug, provides that the coupling plug has a first inner, media-carrying pipe element and a first outer pipe element that coaxially surrounds the first inner pipe element at a radial distance. An evacuable first free space is formed between these two first pipe elements. The coupling socket has a second inner pipe element and a second outer pipe element that coaxially surrounds the second inner pipe element at a radial distance. An evacuable second free space is formed between these two second pipe elements. The first inner pipe element is detachably connected or connectable to the second inner pipe element. The first outer pipe element is detachably connected or connectable to the second outer pipe element.

[0011] This previously known arrangement is now characterized according to the invention by an additional drive element that is connected or connectable to the coupling plug and that has a first engagement structure that is complementary to a second engagement structure on the coupling socket, or vice versa. Furthermore, according to the invention, after the first engagement structure and the second engagement structure have been brought into engagement, an axial relative movement of the coupling plug and coupling socket is caused or can be caused by a rotational movement about a common longitudinal axis of the pipe elements applied externally to the drive element (i.e., a corresponding torque). This creates or allows for the formation of a secure and defined fluid-tight connection between the first inner pipe element and the second inner pipe element at the cold end.

[0012] It is therefore proposed according to the invention to use an additional drive element to effect an axial relative movement of the inner pipe elements in order to form the connection at the cold end in a process-reliable manner by targeted and definable rotational action (i.e. a torque) from the outside on the drive element and to avoid leakage of process fluid (i.e. cryogenic medium) and the associated problems.

[0013] In this context, the present invention proposes two basic embodiments or variants, which will be discussed in more detail below.

[0014] In both variants, a further development of the coupling according to the invention provides that in the area of ​​the connection, a sealing chamber with defined dimensions is formed at least in the axial direction between the first inner pipe element and the second inner pipe element, in which a seal is received.

[0015] By providing such a sealing chamber with defined dimensions, at least in the axial direction, improved sealing against the escape of the process medium into an area between the pipelines can be achieved reliably and reproducibly.

[0016] In both variants, a further development of the coupling according to the invention provides that the sealing chamber is formed by arranging the two inner pipe elements in a block configuration. This does not have to be done directly, but can be achieved by interposing further (pipe) elements.

[0017] By arranging the two inner pipe elements flush, the sealing effect can be adjusted precisely, safely and reproducibly: As soon as the torque required to tighten the connection increases significantly, the two inner pipe elements are flush against each other, and the intended seal is achieved.

[0018] In both variants, a further development of the coupling according to the invention provides that the sealing chamber is formed between a terminal end element of the coupling plug and a terminal end element of the coupling socket, preferably as a circumferential recess in the terminal end element of the coupling socket or the coupling plug.

[0019] These end elements are regularly designed in the form of turned parts, so that the necessary recesses for creating the sealing chamber can be produced easily and reliably, while the sealing chamber also has the required stability.

[0020] In both variants, a further development of the coupling according to the invention provides that the axial dimension of the sealing chamber is limited by an axial excess of an axial projection of the terminal end element of the coupling plug beyond the remaining terminal end element of the coupling plug, or by an axial excess of an axial projection of the terminal end element of the coupling bushing beyond the remaining terminal end element of the coupling bushing. These end elements serve in particular to connect the inner, media-carrying pipe elements.

[0021] The aforementioned excess or projection allows the mechanical contact between the two inner pipe elements ("on the block") mentioned above to be reliably and reproducibly established without affecting more sensitive components of the arrangement (e.g. sealing elements).

[0022] In both variants, a further development of the coupling according to the invention provides that the drive element is designed to be torsionally stable, in particular using a grooved membrane disc or as an additional pipe element, which is preferably designed at least partially as a corrugated hose, in particular as an annular corrugated hose, most preferably as a bellows, and which does not need to be fluid-tight.

[0023] This enables the transmission of a rotational movement applied externally to the drive element around a common longitudinal axis of the pipe elements and can simultaneously ensure good thermal decoupling of the hot end and cold end by increasing the thermal resistance.

[0024] In a first variant of the coupling according to the invention, it is further provided that the engagement structures are designed as complementary thread structures, preferably as an internal thread on the drive element and as an external thread on the coupling bushing, most preferably on the second inner pipe element, or vice versa.

[0025] In this way, the intended rotational movement exerted on the drive element from the outside around a common longitudinal axis of the pipe elements can be safely and precisely converted into the desired relative movement in the axial direction.

[0026] In the first variant of the coupling according to the invention, it is further provided that, after the first engagement structure and the second engagement structure have been brought into contact, an axial overlap area exists in which a screw connection is formed between the drive element and the coupling bushing. The coupling plug engages axially in the overlap area with a radial engagement projection between the drive element and the second inner pipe element, so that when the screw connection is tightened, the coupling plug is moved or movable axially in the direction of the second inner pipe element (i.e., in the direction of the coupling bushing).

[0027] This represents a preferred embodiment for achieving the desired relative movement in the axial direction. The plug, bushing, and drive element are fundamentally designed and arranged to be free of torsion relative to each other.

[0028] In the first variant of the coupling according to the invention, it is further provided that the aforementioned drive projection is designed as a retaining ring or snap ring, which is partially arranged in a circumferential groove on the coupling plug.

[0029] Such a design is particularly easy and inexpensive to manufacture, which has a positive effect on the overall manufacturing costs of the coupling.

[0030] In the first embodiment of the coupling according to the invention, the drive element extends axially from a "hot end," where the first outer pipe element and the second outer pipe element are connected, to a "cold end," where the first inner pipe element and the second inner pipe element are connected, with the drive element preferably arranged radially between the coupling socket and the coupling plug. In the first embodiment, the "hot end" and "cold end" are not typically located in a common axial position.

[0031] The drive element does not need to be fluid-tight; it can have holes, openings, or similar features as long as it remains torsionally stable. This saves material and weight, and heat conduction can be reduced, which can offer corresponding advantages.

[0032] In this way, a kind of "remote control" of the connection can be implemented, whereby a targeted seal can be achieved at the (poorly or not at all accessible) cold end by applying external pressure in the area of ​​the easily accessible warm end.

[0033] In the first embodiment of the coupling according to the invention, it is further provided that the first outer tube element is designed as a structured tube element, at least in a partial section, and has an outer contour in that partial section that deviates from a smooth cylindrical shape. Preferably, the first outer tube element can have a number of annular bulges in that partial section, or the first outer tube element can have a number of distinct local bulges in that partial section, or the first outer tube element can have a honeycomb-shaped configuration of its outer contour in that partial section.

[0034] Therefore, as part of the aforementioned further development of the first variant, it is proposed that the insulation pipe (i.e., the outer pipe element) of the connector (i.e., the first outer pipe element) of a Johnston coupling be structured, i.e., designed with an outer contour deviating from a smooth cylindrical shape, in order to counteract buckling and thus allow the insulation pipe to be made thinner-walled than in the prior art. This limits heat conduction and reduces heat input. Furthermore, the structuring also contributes to locally stabilizing the aforementioned gas cushion, so that the media's influence on the warm sealing element can be effectively prevented.

[0035] In particular, the design of the aforementioned insulation pipe as a so-called "bulped pipe" with wave-shaped bulges is advantageous, since the wave-shaped cross-section of the structuring significantly increases the resistance to bulging.

[0036] Alternatively or additionally, the drive element can also be designed, at least in a partial section, as a structured tube element (preferably as a so-called "bulged pipe"). The advantage of the "bulged pipe," or other structured tube elements, is increased resistance to bulging, and they provide a guiding function when the coupling is assembled. Since, within the scope of the present invention, the connector's insulation pipe is not pressurized because the seal at the cold end effectively seals, the aforementioned guiding function can also be performed by the drive element. The advantages of a structured insulation pipe discussed below therefore also apply, analogously—with appropriate design—to the drive element.

[0037] Furthermore, this method allows for a local reduction of the gap between the insulation pipe (the inner pipe element) of the socket (i.e., the second inner pipe element) and the drive element. With appropriate design, this creates circumferential chambers between the two insulation pipes or between the insulation pipe of the connector and the drive element of the connected coupling, separated only by narrow annular gaps. These annular gaps can be so small that the heat input from the liquid process medium via the insulation pipes and the drive element forces a phase change in the gap area, thereby forming a localized or even multiple localized gas cushions. This allows the coupling to be positioned independently of the direction of gravity.

[0038] An additional advantage is that the wave-like peaks of the "bulped pipe" act as a guide during coupling and effectively reduce friction between the plug and the drive element.

[0039] The required roundness of the pipe elements (insulation pipes) and the drive element can be achieved by manufacturing them by means of a forming process (calibration), e.g. by internal high-pressure forming or most preferably by bellows pressing.

[0040] The following configurations have proven particularly advantageous in this context (i.e., in the first variant): One embodiment of the coupling according to the invention provides that the outer pipe element of the coupling plug (i.e., the first outer pipe element) has a number of annular protrusions in the section. Preferably, this number is a plurality of protrusions. This allows for the creation of several of the aforementioned narrow annular gaps, which greatly improves the insulating effect.

[0041] One embodiment of the coupling according to the invention provides that the bulges are identically designed. This contributes to a further improved insulating effect and allows the advantageous use of a smooth tube as the outer insulation pipe or as the drive element.

[0042] One embodiment of the coupling according to the invention provides that the bulges, when viewed in a section along a longitudinal axis of the coupling, exhibit an axis-symmetrical configuration with respect to an axis perpendicular to the longitudinal axis through a vertex of the respective bulge. This has proven to be particularly advantageous for reasons of stability.

[0043] One embodiment of the coupling according to the invention provides that the bulges have a continuously curved profile in the direction of the inner pipe element of the coupling plug (i.e., the second inner pipe element) or in the direction of the drive element. This also contributes further to stabilization and is additionally advantageous with regard to the aforementioned reduction in friction.

[0044] Another embodiment of the coupling according to the invention provides that the outer pipe element of the coupling plug has a number of distinct local bulges in the section, which are preferably not continuous throughout. In a specific embodiment, this results in a so-called "dimpled pipe", i.e., a pipe element with a dimpled structure, similar to a golf ball. Such an embodiment is also advantageous for reasons of stability, allowing for less material usage and reduced heat conduction.

[0045] Yet another embodiment of the coupling according to the invention provides that the local bulges are arranged in a regular pattern. According to the applicant's findings, this has proven advantageous because the stability is thus increased uniformly. The joining properties are also correspondingly improved.

[0046] Another embodiment of the coupling according to the invention provides that the outer tube element of the coupling plug has a honeycomb-shaped outer contour in that section. Such a structure is also advantageous for reasons of stability.

[0047] In a further development of this embodiment of the coupling according to the invention, it can be provided that the honeycomb-shaped structure has hexagonal bulges and depressions enclosed by these bulges, or vice versa. This allows comparable advantages to be achieved as with the aforementioned ring-shaped wave structures.

[0048] In another embodiment of the coupling according to the invention, the outer tubular element of the coupling plug rests against the drive element on the inside, particularly with its protrusions according to one of the previously described embodiments. This makes it possible to form the aforementioned separate compartments or circumferential chambers, between which thermally insulating gas cushions can form, further improving the efficiency of the coupling.

[0049] In another embodiment of the coupling according to the invention, the outer tubular element of the coupling plug is axially pre-tensioned, particularly during the actual coupling process, in order to specifically shape the radial outward bulges and to close or at least minimize gaps, especially annular gaps, between the outer tubular element of the coupling plug and the drive element. The advantages associated with this have already been mentioned above.

[0050] In another embodiment of the coupling according to the invention, it is further provided that a local sealing element insert is arranged between the outer tube element of the coupling plug and the drive element, at least in the area of ​​a subset of the protrusions, preferably in all protrusions. This further improves the closing of the (ring) gap.

[0051] In a further embodiment of the coupling according to the invention, it is additionally provided that the sealing element insert consists of a metal, preferably indium. Metallic seals are generally resistant to high vacuums and are durable. The choice of indium, in particular, can ensure that no additional increased thermal conductivity occurs, as would be the case, for example, with the use of copper.

[0052] In another embodiment of the coupling according to the invention, it is further provided that at least the outer tube element of the coupling plug is a cost-effective longitudinally welded tube, which has preferably been modified by forming, such as preferably internal high-pressure forming or most preferably by bellows pressing. These processes are known to those skilled in the art. This results in improved roundness and, at the same time, improved sealing, as already mentioned.

[0053] In another embodiment of the coupling according to the invention, it is further provided that at least the outer tube element of the coupling plug has a variable wall thickness in the axial and / or circumferential direction.

[0054] The term "variable wall thickness" means that the wall thickness is not constant, but rather assumes different values ​​in the axial direction (along the longitudinal axis) and / or in the circumferential direction. This characteristic can be used to advantage during the forming process. Furthermore, the applicant has determined that such a change in wall thickness also increases the stability of the insulation pipe and leads to reduced material usage (resulting in lower thermal conductivity).

[0055] In yet another embodiment of the coupling according to the invention, the outer tubular element of the coupling plug is stabilized by additional elements, such as stabilizing rings, which are preferably positively locked, and most preferably materially bonded. These additional elements are preferably arranged at selected positions along the outer tubular element of the coupling plug. They can help to selectively influence or mitigate its buckling behavior. In the hot area, they preferably consist of plastic, preferably fiber-reinforced, most preferably G10, and in the cold area of ​​steel, preferably austenitic steel, which can be materially bonded / fixed. However, to achieve the advantage of using identical parts, the embodiment can also be limited to only one (identical) design.

[0056] In this way, the present invention, particularly in the first variant, achieves the following further advantages over the prior art: lightweight construction with reduced material usage, increased robustness against buckling, enabling installation in any orientation, and reduced heat input. Furthermore, due to the improved thermal decoupling, a shorter overall length than that achieved with the prior art can be realized.

[0057] Another further development of the coupling according to the invention of the first variant provides that the section in which the first outer pipe element is structured coincides axially with a section of the drive element in which the drive element is designed as a smooth tube, and vice versa.

[0058] In this way, the first outer pipe element and the drive element are geometrically completed, which can contribute to a reduced overall size.

[0059] Another further development of the coupling according to the invention of the first variant provides that the drive element has a radial projection accessible from the outside, preferably with a regular hexagonal shape.

[0060] In this way, the required rotational action can be achieved as easily as possible and with standard tools.

[0061] Another further development of the coupling according to the invention of the first variant provides that the drive element is connected or connectable to the coupling plug via the radial projection, preferably by means of a first clamp.

[0062] This represents a simple and well-established connection option that can be implemented without significant (cost) effort.

[0063] Another further development of the coupling according to the invention of the first variant provides that the drive element has an external threaded section.

[0064] This threaded section allows for the attachment of further components of the coupling, which will be discussed below.

[0065] Another further development of the coupling according to the invention of the first variant provides that a screw-on part is screwed or can be screwed onto the threaded section, in particular in the manner of a lock nut, preferably up to the coupling bushing (as a pressure stop).

[0066] In this way, a simple way is created to axially fix the coupling bushing and screw-on part (and via this also the coupling plug) relative to each other and to compensate for tolerances.

[0067] Another further development of the coupling according to the invention of the first variant provides that the drive element is connected or connectable to the coupling bushing via the screw-on part, preferably by means of a second clamp, and acts as a tie rod.

[0068] This in turn represents a simple and well-established connection option that can be implemented without significant (cost) effort.

[0069] In the following, certain advantageous further developments of the aforementioned second variant of the coupling according to the invention will be described in more detail, which are based on the solution known from DE 10 2022 110 880 A1: A further development of the coupling according to the invention, of the second variant, provides that the drive element has a first, annular outer connecting part and a second, annular inner connecting part, which are arranged concentrically and together form the first engagement structure and are connected in a torsionally rigid manner by means of a radially extending first grooved membrane disk. The first grooved membrane disk can, in particular, be bonded to the two connecting parts by means of a material bond.

[0070] The term "torsionally rigid" means here and in the following that torques can be transmitted by means of the connection in question (or a correspondingly designed component, e.g. the aforementioned grooved membrane disc).

[0071] The grooved membrane disc ensures effective thermal decoupling of the two connecting parts without requiring more space in the axial direction. The concentric connecting parts contribute to a particularly strong and secure connection. Furthermore, the grooved membrane disc enables torque transmission, which will be discussed in more detail below.

[0072] In the second variant, the "warm end" and "cold end" are regularly located at least approximately in a common axial position.

[0073] A further development of the coupling according to the invention of the second variant provides that the coupling bushing has first connection structures on the second outer pipe element and second connection structures on the second inner pipe element, which together form the second engagement structure.

[0074] In this way, together with the aforementioned concentric connecting parts, a particularly good and secure connection can be created.

[0075] A further development of the coupling according to the invention, of the second variant, provides that the first engagement structure and the second engagement structure are designed in the manner of a bayonet fitting and interact accordingly. Preferably, the first connection structures can interact with the first connection part, and the second connection structures can interact with the second connection part.

[0076] Bayonet fittings are known to those skilled in the art. In the present context, the bayonet fitting advantageously ensures that the intended axial movement can be achieved with only a small (i.e., limited in the circumferential direction) rotational movement.

[0077] A further development of the coupling according to the invention of the second variant provides that the coupling bushing has a radially extending second grooved membrane disc which connects the second outer pipe element and the second inner pipe element and which is arranged in a form-fitting manner to the first grooved membrane disc.

[0078] In this context, the term "form-fit" means that the first grooved diaphragm disc and the second grooved diaphragm disc lie congruently on top of each other (i.e., their wave crests and troughs can interlock) when the clutch is closed.

[0079] The second grooved membrane disc can be specifically designed to seal a radial free space between the second outer pipe element and the second inner pipe element in the area of ​​the coupling bushing against the environment, thus making it evacuatable, which can improve thermal insulation.

[0080] A further development of the coupling according to the invention of the second variant provides that the second grooved diaphragm disc is axially supported on the rear side.

[0081] This increases resistance to ambient pressure after evacuation. "Rear" refers to the side facing away from the coupling point.

[0082] A further development of the coupling according to the invention of the second variant provides that the first grooved diaphragm disc and the second grooved diaphragm disc have different dimensions in the radial direction.

[0083] This allows for different (radial) dimensions of the pipe elements or connecting parts in the area of ​​plug and socket to be taken into account.

[0084] A further development of the coupling of the second variant according to the invention provides that the coupling plug has a radially extending third grooved membrane disc which connects the first outer pipe element and the first inner pipe element and which is arranged in a form-fitting manner to the first grooved membrane disc and the second grooved membrane disc.

[0085] In this context, the term "form-fit" means that the first grooved diaphragm disc, the second grooved diaphragm disc and the third grooved diaphragm disc lie congruently on top of each other (i.e., can interlock with their wave crests and troughs), especially when the clutch is closed.

[0086] The third grooved membrane disc can be specifically designed to seal a radial free space between the first outer pipe element and the first inner pipe element in the area of ​​the coupling plug from the environment, thus making it evacuatable, which can improve thermal insulation.

[0087] A further development of the coupling according to the invention, of the second variant, provides that the third grooved diaphragm disc is axially supported on its rear side. "Rear side" again refers to the side facing away from the coupling point.

[0088] This can increase resistance to ambient pressure after evacuation.

[0089] A further development of the coupling according to the invention of the second variant provides that the first grooved diaphragm disc and the third grooved diaphragm disc have the same dimensions in the radial direction.

[0090] This ensures improved stability and is possible because both of the aforementioned grooved membrane discs are arranged on the same component (the connector).

[0091] In a composite state of the coupling, the first grooved diaphragm disc is preferably arranged between the second and the third grooved diaphragm discs, with the latter two each being axially supported from the outside.

[0092] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing. Fig. Figure 1 shows a coupling according to the invention in the first variant in its individual parts; Fig. Figure 2 shows the essential components of the coupling. Fig. 1 in longitudinal section; Fig. 3 shows the clutch. Fig. 1 in longitudinal section and in the composite state; Fig. 4 shows a coupling according to the invention in the second variant in longitudinal section and in an open state; Fig. 5 shows the clutch off Fig. 4 in their closed state; Fig. Figure 6 shows a detailed view of the coupling bushing according to the design in Fig. 4; Fig. Figure 7 shows a detailed view of the coupling plug according to the design in Fig. 4; Fig. Figure 8 shows a cutaway partial view of a coupling according to the invention in a different embodiment.

[0093] In all figures, identical reference symbols denote identical or at least equivalently functioning elements. The terms "pipe element" and "pipeline element" are consistently used synonymously.

[0094] In the Fig. Figure 1 shows an exploded view of a coupling 1 of the first variant according to the invention with longitudinal axis L. Reference numeral 2 designates the coupling plug (plug), and reference numeral 3 designates the coupling socket (socket). A tubular drive element 4 is arranged between them, which, further below, is also provided with reference numeral 36. The coupling 1 also comprises two clamps 5, 6, two centering elements 7, 8, a screw-on part 9, and two seals (sealing rings) 10, 11. All these elements and their interaction will be discussed in more detail below.

[0095] According to plug 2, Fig. 2, partial figure a), in short: Fig. 2a) Starting from its front insertion end 12, two coaxial pipe elements extend, namely an inner (media-carrying) pipe element 13 and an outer pipe element 14. The outer pipe element 14 is partially designed as a structured pipe element and accordingly has an outer contour that deviates from a smooth cylindrical shape over most of its length. Specifically, it is structured over most of its longitudinal extent as a "bulbed pipe" with several identical annular protrusions 15, only one of which is explicitly designated. This allows the pipe element 14 to be made lighter and thinner while maintaining the same or even improved (pressure) stability. Preferably, the outer pipe element 14 of the coupling plug 2 is manufactured by forming, such as preferably internal high-pressure forming or most preferably bellows pressing.

[0096] At one end 16 (the so-called "warm end"), the outer pipe element 14 is radially expanded and has no bulges in this area. In a transition area between the bulges 15 and the expanded end 16, an approximately triangular cross-section elevation 17 is provided on the outside, which will be discussed in more detail later.

[0097] At the other end 18 (the so-called "cold end"), a first end element 19 is arranged, which fluid-tightly connects the inner pipe element 13 and the outer pipe element 14, preferably by a material bond. The end element 19 has a front end face 19a with an inner, circumferential projection 19b. A retaining projection 21 in the form of a locking ring is arranged in a circumferential groove 20 of the end element 19. Reference numeral 22 shows a multi-layer insulation (MLI), i.e., a multi-layer insulation arranged between the inner pipe element 13 and the outer pipe element 14. The multi-layer insulation is generally designed in the form of a multi-layered, highly (radiation-)reflective film or the like, which is known to those skilled in the art.

[0098] According to Fig. 2, partial figure b), in short: Fig. 2b), also two coaxial tube elements, namely an inner tube element 23 and an outer tube element 24, between which a multi-layer insulation (MLI) 25 is arranged. The two coaxial tube elements 23, 24 of the socket 3 are fluid-tightly connected to each other at one end 26 (the "warm end" corresponding to reference numeral 16) via a second end element 27, preferably by a material bond. The second end element 27 has a shape at reference numeral 28 that is mirror-symmetrical to the triangular protrusion 17 of the plug 2. The inner tube element 23 of the socket 3 is connected at its free end (right in Fig. 2b)) is tapered in cross-section and has a fluid-conducting (media-carrying) pipe extension 29 connected to the remaining inner pipe element 23 of the socket 3, the diameter of which is adapted to that of the inner (media-carrying) pipe element 13 of the plug 2. Pipe extension 29 and inner pipe element 13 of the plug 2 are connected by means of a seal (in Fig. 2 (not shown) connected as fluid-tight as possible, which is described in more detail below.

[0099] In a transition area 30 from the inner tube element 23 to the tube extension 29, the bushing 3 has an annular reducing part 31, which is preferably formed in a material-fit connection with the inner tube element 23 and integrally with the tube extension 29 and which has an axial projection 32 with external thread 33, a (surface-) structured radial surface 34 and a recess 35 in the transition area between radial surface 34 and tube extension 29.

[0100] Fig. 2, partial figure c), in short: Fig. 2c), shows the additional drive element 36, which is located in Fig. 1, designated with reference numeral 4, and which is to be arranged radially between plug 2 and socket 3, as shown below. Fig. 3 will be shown more clearly later. The drive element 36 is tubular in shape overall and has a smooth cylindrical section 37 and an annularly corrugated section 38. The smooth cylindrical section 37 corresponds in its longitudinal dimension to the structured section of the tubular element 14, while the annularly corrugated section 38 corresponds in its longitudinal dimension to the smooth cylindrical "remainder" of the tubular element 14. A ring part 39 with an internal thread 40 is connected end-to-end (materially bonded) to the annularly corrugated section 38. At the other end, the drive element 36 has a chamfered radial projection 41 (preferably with an external hexagonal contour), an external thread 42, and two circumferential grooves 43, 44, which are designed to receive the sealing rings 10, 11. Fig. 1 serve.

[0101] Fig. Figure 3 shows the assembled coupling 1. For improved clarity, not all elements are labelled again. To tightly connect plug 2 and socket 3 at the cold end 18, the drive element 36 is inserted into socket 3, and plug 2 is in turn inserted into the drive element 36. If the drive element 36 is now rotated about the longitudinal axis L and its internal thread 40 (see Figure 3) Fig. 2) on the external thread 33 (see Fig. 2) the socket 3 is screwed on, which corresponds to the embodiment a) according to the invention, it takes the plug 2 due to the retaining ring 21 (cf. Fig. 2) in the axial direction until its projection 19b abuts the end of the recess 35 of the socket 3. In other words, when the drive element 36 reaches the retaining ring 21, a fixed connection in the axial direction between the drive element 36 and the plug 2 is formed. Then, a sealing chamber 45 with a well-defined (axial) dimension A is formed between the end face 19a of the plug 2 and the radial surface 34 of the socket 3. A seal (sealing ring) 46 is inserted into this chamber, ensuring a secure seal at the cold end 18, while the drive element 36 can be conveniently (remotely) operated from the warm end 16.

[0102] To secure the connection at the warm end 16, the plug 2 has the aforementioned, approximately triangular or conical-shaped elevation 17 on the outside (see figure). Fig. 2), to which the drive element 36 with its projection 41 (cf. Fig. 2) fits snugly. It is secured in this area by means of the clamp 5. Furthermore, the screw-on part 9 is screwed onto the external thread 42 of the drive element 36, similar to a lock nut, up to the projection 28 of the bushing 3. It is also secured here by means of the clamp 6.

[0103] In the coupling 1 shown, after the first engagement structure (in particular the internal thread 40 of the drive element 36, cf.) has been engaged, the following results: Fig. 2) and the second engagement structure (in particular the external thread 33 of the bushing 3, cf. Fig. 2) an axial overlap area in which a screw connection is formed between the drive element 36 and the coupling bushing 3. The coupling plug 2 engages with its radial drive projection 21 (see figure). Fig. 2) in this overlap area axially between the drive element 36 and the second inner pipe element 23 or the reducing part 31, so that the coupling plug 2 can be moved or is moved axially in the direction of the second inner pipe element 23 or the radial surface 34 of the reducing part 31 when the screw connection is tightened.

[0104] The clamp (V-shaped clamp) 5 serves to detachably connect plug 2 and drive element 4, 36, and the clamp (V-shaped clamp) 6 serves to detachably connect drive element 4 or 36 and socket 3. Reference numerals 7 and 8 denote the centering or stabilizing elements already mentioned above. These stabilizing elements 7, 8 ensure that the inner tube element 13 is centered within the outer tube element 14 in the region of the extended end of plug 2 or of the tube extension 29 within the outer tube element 24; they are preferably made of a poorly thermally conductive material that is vacuum-compatible (no outgassing) and preferably consists of a fiber-reinforced plastic, most preferably of glass fiber-reinforced plastic, such as G10.

[0105] Fig. Figure 3 shows – as already mentioned – the connected state of the coupling 1. In this state, the coupling bushing 3 and the coupling plug 2 are detachably connected to each other by a first connection located at the hot end 16 in the area of ​​their outer pipe elements 14 and 24, respectively (by means of the clamps 5, 6 and with the drive element 4 or 36 interposed). Furthermore, in the connected state, a joint gap at the other, cold end 18 between the coupling bushing 3 and the coupling plug 2 in the area of ​​their inner pipe elements 13 and 23, 29, respectively, is sealed by the seal 46.

[0106] How to Fig. 3, the bulges 6 of the tube element 14, in a section along the longitudinal axis L of the coupling 1, exhibit a symmetrical shape with respect to a plane perpendicular to the longitudinal axis L through a vertex (not labeled) of a respective bulge 15. Furthermore, the bulges 15 have a continuously curved, i.e., convex, shape in the direction of the longitudinal axis L, tubular element 13 of the coupling plug 2.

[0107] The outer tubular element 14 of the coupling plug 2 rests with its protrusions 15 on the inside of the drive element 36 in its smooth cylindrical section. To achieve this, the outer tubular element 14 of the coupling plug 2 can be axially pre-tensioned during the coupling process, so that the protrusions 15, in particular, are formed radially outwards to close gaps, especially annular gaps, between the outer tubular element 14 of the coupling plug 2 and the drive element 36. In this way, separate annular cavities 47 are formed along the coupling 1, which ensure that as little cryogenic fluid as possible reaches the "warm" sealing elements 10, 11 and damages them. In any case, the annular gaps that may remain between the elements 14 and 36 ensure that any cryogenic fluid that has penetrated evaporates and forms efficient insulating gas cushions to prevent further heat input from the outside.

[0108] Although this is not shown in the figures, at least in the area of ​​a subnumber of the bulges 15, an additional local sealing element insert can be arranged between the outer tube element 14 of the coupling plug 2 and the drive element 36, which sealing element insert consists in particular of a metal, preferably indium.

[0109] The Fig. 4, Fig. 5, Fig. 6 to Fig. Figure 7 shows an alternative design of the coupling 1', which differs significantly from the variant according to the figure in the design of the "warm" connection and the drive element. Fig. 1, Fig. 2 to Fig. 3 differs.

[0110] Fig. Figure 4 shows the coupling 1' in its open state. Essentially, only the most important differences from the first design are discussed in detail.

[0111] The coupling 1' has a drive element 48 in the area of ​​the plug 2, which comprises a first, annular outer connecting part 49 with a radial projection 49a, preferably with an outer hexagonal contour, and a second, annular inner connecting part 50, which are arranged concentrically and together form a first, plug-side engagement structure, specifically designed in the manner of a bayonet fitting. The connecting parts 49, 50 are connected by means of a radially extending first grooved membrane disk 51. This first grooved membrane disk 51 is bonded to the two connecting parts 49, 50. It enables torque to be transmitted from the first connecting part 49 to the second connecting part 50 by means of the drive element 48 and, due to its effective length in the radial direction, ensures a relatively high thermal resistance.The outer connecting part 49 is attached via a retaining ring 49b to a multi-stepped pipe section 14a, which represents an axial extension (bonded) of the first outer pipe element 14.

[0112] Accordingly, at coupling 1', the following applies: Fig. 4 provided that the coupling bushing 3 is attached to the second outer pipe element (at reference numeral 24, only indicated; cf. Fig. 5) first connection structures 52 and on the second inner pipe element 23 second connection structures 53 which together form a second, bushing-side engagement structure.

[0113] As already mentioned, in this variant the first, plug-side engagement structure and the second, socket-side engagement structure are designed like a bayonet fitting and interact accordingly, with the first connection structures 52 interacting with the first connection part 49 and the second connection structures 53 interacting with the second connection part 50. Bayonet fittings are well known to those skilled in the art, so the exact design need not be discussed here. Closing the bayonet fitting by a corresponding (relative) rotational movement of plug 2 and socket 3 not only ensures a secure locking of the coupling 1', but also causes an axial relative movement of plug 2 and socket 3 for sealing purposes, which will be discussed in more detail below.

[0114] First, it should be noted that in coupling 1', the coupling socket 3 has a radially extending second grooved membrane disc 54, which connects the second outer pipe element 24 and the second inner pipe element 23 via the connecting structures 52, 53, so that an intermediate gap or free space 55 can be evacuated, and which is arranged in a form-fitting manner to the first grooved membrane disc 51, which in this case means that the grooved membrane discs 51 and 54 interlock with their wave troughs and crests when plug 2 and socket 3 are coaxially aligned along the longitudinal axis and axially brought together (see below, Fig. 5).

[0115] According to Fig. In connector 2, the first outer tube element 14 and also the first inner tube element 13 are largely designed as an annular corrugated hose. Between them is an intermediate space or free space 56, the MLI 22, and a braided hose 57 that surrounds the inner tube element 13 for stabilization. The free space 56 can be evacuated via a connection nozzle 57. Reference numeral 58 designates an adsorber.

[0116] For this purpose, the coupling 1' or the coupling plug 2 also has a radially extending third grooved membrane disc 59, which connects the first outer pipe element 14 in the area of ​​the extension pipe section 14a and the first inner pipe element 13 in the area of ​​the end element 19 in a material-fit manner, so that the space or free space 56 can be evacuated. The third grooved membrane disc 59 is positively locked specifically to the first grooved membrane disc 51 and (when the coupling 1' is closed, see Figure 1). Fig. 5) also arranged to the second grooved membrane disk 54, as defined above. In the Fig. 4 The grooved membrane discs 51 and 59 are already interlocking so that they are no longer recognizable as separate entities.

[0117] In order to better withstand the ambient pressure during evacuation of the spaces 55, 56, the second grooved membrane disk 54 and the third grooved membrane disk 59 are each axially supported on their rear side, for which at least one corresponding support element 60, 61 is provided, as shown.

[0118] While the first grooved membrane disk 51 and the second grooved membrane disk 54 have different dimensions in the radial direction, preferably the first grooved membrane disk 51 and the third grooved membrane disk 59 have the same dimensions in the radial direction, as shown.

[0119] The so-called “cold end” 18 according to the design in Fig. 4 is arranged internally. The aforementioned end element 19 is also located there, which fluid-tightly connects the inner tube element 13 and the outer tube element 14, including the extension 14a (via the grooved membrane disc 59), to each other in a material-bonded manner. The end element 19, in turn, has a front end face 19a with an internal, circumferential projection 19b. Reference numeral 46 again denotes a seal. A retaining ring 21 is arranged in a circumferential groove 20 of the end element 19, which, in conjunction with a spring 62 and a circumferential projection 63, ensures that the connecting part 50 is securely held on the end element 19.

[0120] Analogous to the design of socket 3 according to Fig. 2 can also be found there in Fig. 4 a ring part 31 with radial surface 34 and recess 35 to provide, in conjunction with the connector 2, a sealing chamber of defined (axial) dimensions when the end element 19 and the ring part 31 with the projection 19b in the area of ​​the recess 35 come into contact. This is in the Fig. 5 shown.

[0121] Fig. 5 shows the clutch 1' off Fig. 4 in their closed state. For the sake of clarity, not all elements are explicitly labelled again (see below). Fig. 4) The engagement structures interact like a bayonet fitting, as explained in detail above. All three grooved membrane discs 51, 54, 59 then fit together in a form-fitting manner. The sealing chamber 45 has a defined dimension A in the axial direction, as shown above with reference to Fig. 3 described. Here too, the tightening of the connection at the cold end 18 is achieved by applying a torque to a drive element 48 at the warm end 16, specifically by acting on the element 49 (at reference numeral 49a) to close the bayonet fitting and at the same time to cause an axial relative movement, especially of parts 19 and 31, which creates the described seal at the cold end 18.

[0122] Fig. Figure 6 shows a perspective detail view of the socket 3 and illustrates the possible design of the bayonet-type connection structures 52, 53 as well as the design of the relevant grooved membrane disc 54.

[0123] Fig. Figure 7 shows a perspective detail view of connector 2 and illustrates the possible design of the complementary bayonet-type connection structures on the connecting parts 49, 50, as well as the design of the relevant grooved membrane disc 51, which is used for torque transmission. The torque acts accordingly at reference numeral 49a. For this purpose, element 49 also has recesses 49c. Alternatively, a design with a hexagonal contour is also possible in this area.

[0124] In the Fig. 8 is a partially different design in the Fig. 1, Fig. 2 to Fig. 3. Modification shown, corresponding to embodiment b) according to the invention, is shown. Only the essential differences from the embodiment already described according to Figures 1 to 3 will be discussed in more detail here:

[0125] According to Fig. The external thread 40, which forms part of the described engagement structure, is not located on the socket 3, but on the plug 2. A ring section 39 with an internal thread 40 is connected end-to-end (materially interlocked) to the ring-corrugated section 36 of the drive element 36. In contrast, the retaining ring 21 is not located on the plug 2, but between the ring section 39 and the reducing section (terminating element) 31 of the socket 3.

[0126] In this way, socket 3 and drive element 36 can be pre-assembled. The described axial relative movement of coupling plug 2 and coupling socket 3 after engagement of the first engagement structure and the second engagement structure can also be achieved here by a rotational movement about a common longitudinal axis L of the pipe elements exerted on the drive element 36 from the outside, thereby creating or enabling a fluid-tight connection.

[0127] One can recognize in the Fig. 8. Furthermore, that, deviating from the design in the Fig. 1, Fig. 2 to Fig. 3. In the present case, it is not the connector 2 (specifically the insulation tube "male", element 14) that is designed as a bulbed pipe, but rather the drive element 36 in a partial section (to the left of the corrugated section 38). As already mentioned, a significant advantage of the bulbed pipe is its increased resistance to bulbing. However, in the present invention, the insulation pipe 14 is not pressurized, since the cold seal 46 effectively seals it. Therefore, the guide bulbs can also be located in the drive element 36. This also applies in principle to the embodiment according to the Fig. 1, Fig. 2 to Fig. 3. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 41 07 652 A1

[0003] EP 3 339 713 B1

[0003] DE 10 2022 110 880 A1 [0007, 0069]

Claims

[1] Coupling (1, 1') for cryogenic conduits with a coupling socket (3) and a coupling plug (2), wherein: the coupling plug (2) has a first inner, media-carrying pipe element (13) and a first outer pipe element (14) which coaxially surrounds the first inner pipe element (13) at a radial distance, between which first pipe elements (13, 14) an evacuable first free space (56) is formed; the coupling bushing (3) has a second inner pipe element (23, 29) and a second outer pipe element (24) which coaxially surrounds the second inner pipe element (23, 29) at a radial distance, between which second pipe elements (23, 24) an evacuable second free space (55) is formed; the first inner piping element (13) is detachably connected or connectable to the second inner piping element (23, 29); the first outer pipe element (14) is detachably connected or connectable to the second outer pipe element (24); characterized by a drive element (4, 36; 48) that is connected or connectable to the coupling plug (2) and that a) has a first engagement structure that is complementary to a second engagement structure on the coupling socket (3), or that b) has a first engagement structure that is complementary to a second engagement structure on the coupling plug (2); wherein, after the first engagement structure and the second engagement structure have been brought into contact, an axial relative movement of the coupling plug (2) and coupling socket (3) is caused or can be caused by a rotational movement about a common longitudinal axis (L) of the pipe elements (13, 14, 23, 24) exerted from the outside on the drive element (4, 36; 48), wherein a fluid-tight connection is created or can be created between the first inner pipe element (13) and the second inner pipe element (23, 29). [2] Coupling (1, 1') according to claim 1, in which a sealing chamber (45) with defined dimensions (A) is formed at least in the axial direction in the area of ​​the connection between the first inner pipe element (13) and the second inner pipe element (23, 29), in which a seal (46) is received. [3] Coupling (1, 1') according to claim 2, wherein the sealing chamber (45) is formed by the two inner pipe elements (13, 23) being arranged on a block. [4] Coupling (1, 1') according to claim 2 or 3, wherein the sealing chamber (45) is formed between a terminal end element (19) of the coupling plug (2) and a terminal end element (29, 31) of the coupling socket (3), preferably as a circumferential recess in the terminal end element of the coupling socket (3) or of the coupling plug (2). [5] Coupling (1, 1') according to claim 4, wherein an axial dimension of the sealing chamber (45) is limited by an axial excess of an axial projection (19b) of the terminal end element (19) of the coupling plug (2) beyond the remaining terminal end element (19) of the coupling plug (2) or by an axial excess of an axial projection of the terminal end element of the coupling socket (3) beyond the remaining terminal end element of the coupling socket (3). [6] Coupling (1) according to one of the preceding claims, wherein the drive element (4, 36; 48) is designed to be torsionally stable, in particular using a grooved membrane disc (51) or as an additional pipe element (4, 36) which is preferably designed at least partially as a corrugated hose, most preferably as an annular corrugated hose (38) or bellows. [7] Coupling (1) according to one of the preceding claims, wherein the engagement structures are designed as complementary thread structures, preferably as internal threads (40) on the drive element (4, 36) and as external threads (33) on the coupling bushing (3), most preferably on the second inner pipe element (23, 29), or vice versa. [8] Coupling (1) according to claim 7, in which, after engagement of the first engagement structure and the second engagement structure, an axial overlap area exists in which a screw connection is formed between the drive element (4, 36) and the coupling bushing (3), wherein the coupling plug (2) engages axially in the overlap area with a radial engagement projection (21) between the drive element (4, 36) and the second inner pipe element (23, 29), so that the coupling plug (2) is movable axially in the direction of the second inner pipe element (23, 29) when the screw connection is tightened. [9] Coupling (1) according to claim 8, wherein the drive projection (21) is designed as a retaining ring or snap ring, which is partially arranged in a circumferential groove (20) on the coupling plug (2). [10] Coupling (1) according to one of claims 7 to 9, wherein the drive element (4, 36) extends axially from a “hot end” (16, 26) in which the first outer pipe element (14) and the second outer pipe element (24) are connected to each other, to a “cold end” (18) in which the first inner pipe element (13) and the second inner pipe element (23, 29) are connected to each other, wherein the drive element (4, 36) is preferably arranged radially between coupling socket (3) and coupling plug (2). [11] Coupling (1) according to one of claims 7 to 10, wherein the first outer tube element (14) or the drive element (4, 36) is designed as a structured tube element at least in a partial section and has an outer contour in the partial section that deviates from a smooth cylindrical shape, preferably wherein the first outer tube element (14) has a number of annular bulges (15) in the partial section or wherein the first outer tube element (14) has a number of distinct local bulges in the partial section or wherein the first outer tube element (14) has a honeycomb-shaped design of its outer contour in the partial section. [12] Coupling (1) according to claim 11, wherein the partial section of the outer tube element (14) coincides axially with a partial section of the drive element (4, 36) in which the drive element (4, 36) is designed as a smooth tube (37), or vice versa. [13] Coupling (1) according to one of claims 7 to 12, wherein the drive element (4, 36) has an externally accessible radial projection (41), preferably with a regular hexagonal shape. [14] Coupling (1) according to claim 13, wherein the drive element (4, 36) is connected or connectable to the coupling plug (2) via the radial projection (41), preferably by means of a first clamp (5). [15] Coupling (1) according to one of claims 7 to 14, wherein the drive element (4, 36) has an external threaded section (42). [16] Coupling (1) according to claim 15, wherein a screw-on part (9) is screwed or can be screwed onto the threaded section (42), in particular in the manner of a lock nut, preferably extending to the coupling bushing (3). [17] Coupling (1) according to claim 16, wherein the drive element (4, 36) is connected or connectable to the coupling bushing (3) via the screw-on part (9), preferably by means of a second clamp (6). [18] Coupling (1') according to one of claims 1 to 6, wherein the drive element (48) has a first annular outer connecting part (49) and a second annular inner connecting part (50) which are arranged concentrically and together form the first engagement structure and which are connected by means of a radially extending first grooved membrane disk (51), wherein preferably the first grooved membrane disk (51) is bonded to the two connecting parts (49, 50). [19] Coupling (1') according to claim 18, wherein the coupling bushing (3) has first connection structures (52) on the second outer pipe element (24) and second connection structures (53) on the second inner pipe element (23), which together form the second engagement structure. [20] Coupling (1') according to claim 18, wherein the first engagement structure and the second engagement structure are designed in the manner of a bayonet fitting and interact, wherein preferably and with reference to claim 19 the first connecting structures (52) interact with the first connecting part (49) and the second connecting structures (53) interact with the second connecting part (50). [21] Coupling (1') according to one of claims 18 to 20, wherein the coupling bushing (3) has a radially extending second grooved membrane disc (54) which connects the second outer pipe element (24) and the second inner pipe element (23) and which is arranged in a form-fitting manner to the first grooved membrane disc (51). [22] Coupling (1') according to claim 21, wherein the second grooved diaphragm disc (54) is axially supported on the rear side. [23] Coupling (1') according to claim 21 or 22, wherein the first grooved diaphragm disc (51) and the second grooved diaphragm disc (54) have different dimensions in the radial direction. [24] Coupling (1') according to one of claims 18 to 23, wherein the coupling plug (2) has a radially extending third grooved membrane disc (59) which connects the first outer pipe element (14) and the first inner pipe element (13) and which is arranged in a form-fitting manner to the first grooved membrane disc (51) and the second grooved membrane disc (54). [25] Coupling (1') according to claim 24, wherein the third grooved diaphragm disc (59) is axially supported on the rear side. [26] Coupling (1') according to claim 24 or 25, wherein the first grooved diaphragm disc (51) and the third grooved diaphragm disc (59) have the same dimension in the radial direction.

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