Cryogenic piping couplings

Abstract

This improves sealing at the cold end, reduces the risk of cooling of the "warm" sealing element, and suppresses heat input at the cold end of the coupling. [Solution] A cryogenic piping coupling 1 comprising a coupling socket 3 and a coupling plug 2, wherein the coupling plug has a first internal piping element 13 for transporting a medium and a first external piping element 14 surrounding the first internal piping element coaxially at a radial distance, and a first free space that can be evacuated is formed between the first piping elements; the coupling socket has second internal piping elements 23, 29 and a second external piping element 24 surrounding the second internal piping element coaxially at a radial distance, and a second free space that can be evacuated is formed between the second piping elements; the first internal piping element is detachably connected to the second internal piping element, and the first external piping element is detachably connected to the second external piping element.

Description

Technical Field

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

Background Art

[0002] Such a coupling may be formed particularly as a plug-in coupling for cryogenic piping, and generally includes a coupling socket and a coupling plug. The coupling socket and the coupling plug each have one internal pipe element and an external pipe element arranged coaxially with respect to this internal pipe element. In the connected state, the coupling plug is inserted into the coupling socket. Further, in the connected state, the coupling socket and the coupling plug are detachably connected to each other in the region of their external pipe elements via a first connection portion at one end called their "warm" end. Further, in the connected state, at the other end called the "cold" end, a joint gap in the region of the internal pipe element between the coupling socket and the coupling plug is sealed by a seal. The coupling socket and the coupling plug are usually made of metal, preferably manufactured from (stainless) steel.

[0003] That kind of coupling is also called a Johnston coupling. Examples thereof are known from German Patent Application Publication No. 4107652 or European Patent No. 3339713. Sealing against the system pressure is performed in the so-called warm part of the coupling.

[0004] This thermal sealing means that the two so-called insulated pipes—namely, the inner pipe element of the coupling socket and the outer pipe element of the coupling plug—are subjected to ambient pressure (usually atmospheric pressure). This poses a risk of buckling, especially in the case of the insulated pipe of the coupling plug (hereinafter also referred to simply as "plug"), and therefore, the aforementioned components in conventional technology had to be sized to be correspondingly robust and thick-walled. This, unfortunately, leads to an increase in heat input, particularly to the cold end of the coupling.

[0005] Furthermore, the gap formed between the outer pipe element of the plug and the inner pipe element of the coupling socket (hereinafter also referred to simply as "socket") is periodically partially filled with cryogenic liquid (cryogenic medium) due to insufficient sealing at the cold end. This creates a risk that the insulating gas layer between the sealing element at the warm end and this liquid will be breached by the liquid, resulting in the sealing element being cooled. Consequently, the sealing element becomes brittle, and its sealing function can no longer be guaranteed.

[0006] In this situation, this type of coupling must preferably be positioned such that the normal vector of the coupling separation surface has a positive component parallel to the gravity vector. In other words, since the coupling cannot be mounted perfectly horizontally, the usability of the coupling is limited accordingly.

[0007] From German Patent Application Publication No. 102022110880, an alternative connection arrangement or coupling for cryogenic piping comprising internal and external piping elements is known, in which a spacing element positioned between the internal and external connection elements and closing the free space between the two piping elements to the surroundings is formed as a grooved disc and positioned on a surface extending transversely to the longitudinal axis of the piping. This ensures sufficient path length for incident heat even with a relatively short axial spread, thus enabling good insulation of the connection. However, even here, the aforementioned problems with Johnston couplings may arise due to insufficient sealing of the cold end. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] German Patent Application Publication No. 4107652 [Patent Document 2] European Patent No. 3339713 [Patent Document 3] German Patent Application Publication No. 102022110880 [Overview of the project] [Problems that the invention aims to solve]

[0009] This invention is based on the objective of improving sealing at the cold end by developing the above-described types of couplings. This reduces the risk of cooling of the "warm" sealing element and suppresses heat input at the cold end of the coupling. [Means for solving the problem]

[0010] This problem is solved by a coupling having the features of claim 1, according to the present invention. Advantageous embodiments are defined in the dependent claims.

[0011] A cryogenic piping coupling according to the present invention, comprising a coupling socket and a coupling plug, first, the coupling plug is provided to have a first internal piping element for transporting a medium and a first external piping element coaxially surrounding the first internal piping element at a radial distance. A first free space that can be evacuated is formed between these two first piping elements. The coupling socket has a second internal piping element and a second external piping element coaxially surrounding the second internal piping element at a radial distance. A second free space that can be evacuated is formed between these two second piping elements. The first internal piping element is detachably connected to or connectable to the second internal piping element. The first external piping element is detachably connected to or connectable to the second external piping element.

[0012] This known configuration, according to the present invention, is characterized in that an additional drive element is connected to or connectable to a coupling plug and has a first engagement structure formed complementary to a second engagement structure in the coupling socket, or vice versa. In this case, according to the present invention, after the first and second engagement structures have properly engaged, rotational motion (i.e., corresponding torque) applied externally to the drive element about a common longitudinal axis of the piping elements causes or can cause relative axial motion between the coupling plug and the coupling socket. This ensures or can create a secure and defined fluid-tight connection at the cold end between the first and second internal piping elements.

[0013] Accordingly, it is proposed that, based on the present invention, an additional drive element is used to generate relative axial motion of the internal piping element, thereby applying a suitable and definable rotational action (i.e., torque) to the drive element from the outside, thereby forming a process-stable connection at the cold end and avoiding leakage of process fluid (such as cryogenic medium) and related problems.

[0014] In this regard, the present invention proposes two basic embodiments or variations, which will be discussed in more detail below.

[0015] In both variations, the advanced form of the coupling according to the present invention has a seal chamber of defined dimensions formed at least axially between the first internal piping element and the second internal piping element on the front side of each connection region, and a seal is provided to be housed within this seal chamber.

[0016] By providing a seal chamber of such defined dimensions at least in the axial direction, improved sealing in the area between pipes can be reliably and reproducibly achieved against process medium leakage.

[0017] In both variations, the advanced form of the coupling according to the present invention is configured such that a sealing chamber is formed by arranging two internal piping elements in close contact. This does not have to be done directly, but may be done via other (piping) elements.

[0018] By positioning the two internal piping elements in close contact, the sealing effect can be set accurately, reliably, and reproducibly. When the torque required to tighten the connection increases rapidly, the two internal piping elements come into close contact with each other, achieving the predetermined seal.

[0019] In both variations, the advanced form of the coupling according to the present invention is provided such that the sealing chamber is formed between the terminal element at the end of the coupling plug and the terminal element at the end of the coupling socket, preferably as a circumferential recess of the terminal element at the end of the coupling socket or coupling plug.

[0020] Since these terminal elements are typically formed in the form of rotating parts, the recesses necessary to create a sealing chamber can be created easily and process-stably, and the sealing chamber itself also possesses the necessary stability.

[0021] In both variations, in a development of the coupling according to the invention, the axial dimension of the seal chamber is limited by the axial protrusion of the terminal element at the end of the coupling plug beyond the other terminal element at the end of the coupling plug, or is provided to be limited by the axial protrusion of the terminal element at the end of the coupling socket beyond the other terminal element at the end of the coupling socket. The aforementioned terminal elements are used in particular for connecting internal piping elements for transporting the medium.

[0022] By means of the aforementioned protrusion or protrusions, a further mechanical contact ("tight state") of the two internal pipe elements already described above can be reliably and reproducibly created without affecting more sensitive components of the arrangement (such as seal elements).

[0023] In both variations, in a development of the coupling according to the invention, the drive element is formed to have torsional rigidity, particularly using a grooved membrane disk or as an additional piping element, preferably at least partially as a corrugated hose, particularly as an annular corrugated hose, most preferably as a bellows, and is provided such that it does not need to be fluid-tight.

[0024] This enables the transmission of a rotational movement applied externally to the drive element about the common longitudinal axis of the piping elements, and at the same time, by increasing the thermal resistance, a good thermal insulation between the hot end and the cold end can be achieved.

[0025] In particular, in a first variation of the coupling according to the invention, furthermore, the engagement structure is formed on the drive element as a complementary screw structure, preferably as a female screw, and as a male screw on the coupling socket, most preferably on a second piping element, or is provided to be the reverse.

[0026] In this way, the intentional rotational motion of the piping elements, applied externally to the drive element and centered on the common longitudinal axis, can be reliably and precisely converted into the desired relative motion in the axial direction.

[0027] In particular, in the first variation of the coupling according to the present invention, an axial overlapping region is created after the first and second engagement structures are properly engaged, and in this region a screw connection is formed between the drive element and the coupling socket. The coupling plug is axially engaged between the drive element and the second internal piping element in the overlapping region by radially advancing projections, so when the screw connection is tightened, the coupling plug moves or is movable axially toward the second internal piping element (i.e., toward the coupling socket).

[0028] This constitutes a preferred embodiment for achieving a desirable relative motion in the axial direction. In this case, elements such as plugs, sockets, and drive elements are essentially formed or arranged so as not to twist relative to each other.

[0029] In particular, in the first variation of the coupling according to the present invention, the aforementioned connecting projection is further provided to be formed as a retaining ring or snap ring partially positioned in the circumferential groove of the coupling plug.

[0030] Such embodiments can be manufactured in a particularly simple and low-cost manner, which is advantageous to the overall manufacturing cost of the coupling.

[0031] In particular, in the first variation of the coupling according to the present invention, the drive element further extends axially from the "hot end" where the first external piping element and the second external piping element are connected to each other, to the "cold end" where the first internal piping element and the second internal piping element are connected to each other, and the drive element is preferably provided to be positioned radially between the coupling socket and the coupling plug. In the first variation, the "hot end" and the "cold end" are not usually located in a common axial position.

[0032] The drive element does not need to be fluid-tight; it may have holes, through-holes, etc., as long as torsional rigidity is maintained. This offers corresponding advantages, such as saving material and weight and reducing heat conduction.

[0033] In this way, a kind of "remote control" of the connection becomes possible, allowing for proper sealing of the cold end (which is difficult or impossible to access) by external action in the easily accessible hot end region.

[0034] In particular, in the first variation of the coupling according to the present invention, the first external tube element is further formed as a structured tube element in at least one subsection, and in that subsection, it is provided to have an external contour different from a smooth cylindrical shape. Preferably, the first external tube element may have a plurality of annular bulges in that subsection, or the first external tube element may have a plurality of individual local bulges in that subsection, or the external contour of the first external tube element may have a honeycomb shape in that subsection.

[0035] Therefore, in the process of developing the first variation described above, it is proposed to structure the insulating pipe (i.e., the outer pipe element) of the Johnston coupling plug (i.e., the first outer piping element), that is, to implement an outer contour different from a smooth cylindrical shape, thereby enabling the insulating pipe to be thinner-walled than in the prior art, in order to resist buckling. This limits heat conduction and reduces heat input. In addition, the structuring also contributes to the local stabilization of the gas layer mentioned, thereby efficiently preventing the influence of the medium on the warm sealing element.

[0036] In this context, implementing the aforementioned insulated pipe as a so-called "bulped pipe" with a wavy, bulging section is advantageous because the wavy cross-section resulting from the structuralization clearly increases resistance to buckling.

[0037] Alternatively or additionally, the drive element may also be formed as a structured tubular element (preferably as a so-called "valved pipe") in at least one subsection. The advantage of a "valved pipe" or other structured tubular element is increased resistance to buckling, and these tubular elements assume a guiding function when connecting the couplings. In the present invention, since no pressure is applied to the insulated pipe of the plug and it is effectively sealed by the cold end seal, the aforementioned guiding function can also be performed by the drive element. The advantages of a structured and formed insulated pipe, described later, also apply to the drive element in the corresponding embodiment.

[0038] Furthermore, this method reduces the large localized joint gaps between the socket (i.e., the second internal piping element) and the insulated pipe (internal pipe element) or drive element. In corresponding embodiments, this creates circumferential spaces between the two insulated pipes and between the insulated pipe of the plug and the drive element of the connected coupling, these spaces being separated from each other only by narrow annular gaps. The annular gaps can be made small, thereby forcing a phase change in the gap region due to the heat input through the insulated pipe and drive element, forming one or more localized gas layers. This allows the coupling to be positioned independently of the direction of gravity.

[0039] Additionally, the ridges of the "valved pipe" act as guides during connection, effectively suppressing friction between the plug and the drive element, which is also advantageous.

[0040] The required roundness for tubular elements (insulated pipes) and drive elements can be achieved through forming (calibration) and their manufacture, for example, in the process of internal high-pressure forming or most preferably bellows pressing.

[0041] The following embodiments have proven particularly advantageous in this context (i.e., the first variation).

[0042] In one embodiment of the coupling according to the present invention, the outer pipe element of the coupling plug (i.e., the first outer piping element) is provided to have a plurality of annular bulges in its portion. Preferably, this number is multiple bulges. Accordingly, a plurality of the above-mentioned narrow annular gaps can be formed, which greatly improves the heat insulation effect.

[0043] In one embodiment of the coupling according to the present invention, the bulging portions are provided to be formed uniformly. This contributes to further improving the heat insulation effect and allows the smooth pipe to be advantageously used as an external insulated pipe or as a drive element.

[0044] In one embodiment of the coupling according to the present invention, the bulging portion is provided such that, in a cross-section along the longitudinal axis of the coupling, it has an axis symmetric configuration with respect to an axis perpendicular to the longitudinal axis, passing through the apex of one of the bulges in question. This has proven to be particularly advantageous for reasons of stability.

[0045] In one embodiment of the coupling according to the present invention, the bulging portion is provided to have a shape that curves continuously in the direction of the internal tubular element of the coupling plug (i.e., the second internal piping element) or in the direction of the drive element. This further contributes to stability and is also advantageous in terms of friction suppression, as already mentioned.

[0046] In another embodiment of the coupling according to the present invention, the outer tubular element of the coupling plug has a plurality of individual localized bulges in a portion of its section, which are preferably formed not to be continuous in the circumferential direction. In one specific embodiment, a so-called "dimpled pipe" is produced, i.e., a pipe element having a dimpled structure like that of a golf ball. Such an embodiment is also advantageous for reasons of stability, which allows for a reduction in material usage and a reduction in heat conduction.

[0047] Furthermore, in yet another embodiment of the coupling according to the present invention, localized bulges are provided to be arranged according to a regular pattern. This is advantageous because it uniformly improves stability, as has been found by the applicant. Accordingly, the bonding characteristics are also improved.

[0048] In another embodiment of the coupling according to the present invention, the outer tubular element of the coupling plug is provided such that, in a portion thereof, its outer contour has a honeycomb shape. Such a structure is equally advantageous for reasons of stability.

[0049] In this advanced embodiment of the coupling according to the present invention, the honeycomb shape is provided such that it has hexagonal bulges and recesses surrounded by these bulges, or vice versa. This makes it possible to achieve advantages comparable to the annular wave structure described above.

[0050] In another embodiment of the coupling according to the present invention, the outer tubular element of the coupling plug is in contact with the inside of the drive element, and in particular, is in contact by its bulge, based on any of the embodiments already described. This makes it possible to form the separated regions or circumferential spaces mentioned earlier, and a thermally insulating gas layer can be formed between these spaces, thereby further improving the efficiency of the coupling.

[0051] In another embodiment of the coupling according to the present invention, the outer tube element of the coupling plug is preloaded axially, particularly during the actual coupling process, thereby forming a bulge outward in the radial direction, and closing, or at least making as narrow as possible, the gap between the outer tube element of the coupling plug and the drive element, particularly the annular gap. The advantages associated with this have already been noted above.

[0052] In another embodiment of the coupling according to the present invention, a local sealing element insert is further provided between the outer tube element and the drive element of the coupling plug, in at least a portion of the bulge, preferably in all of the bulge, each of which is positioned. This further improves the closure of the (annular) gap.

[0053] In this advanced embodiment of the coupling according to the present invention, the sealing element insert is further provided to be made of metal, preferably indium. Metal seals generally have high vacuum resistance and load resistance. In particular, the selection of indium can be avoided, which would occur if copper were used, for example.

[0054] In another embodiment of the coupling according to the present invention, at least the outer tubular element of the coupling plug is a cost-effective longitudinally welded pipe, which is configured to be deformed preferably by forming, preferably by internal high-pressure deformation, or most preferably by bellows pressing. These methods are well known to those skilled in the art. This improves roundness and, as already noted, also improves sealing.

[0055] In another embodiment of the coupling according to the present invention, at least the outer tubular element of the coupling plug is provided to have a wall thickness that varies in the axial and / or circumferential direction.

[0056] The term "variable wall thickness" means that the wall thickness is not constant, but takes on various values ​​in the axial direction (along the longitudinal axis) and / or circumferential direction. This situation can, on the one hand, be appropriately utilized during molding. Furthermore, the applicant has confirmed that such wall thickness variations also improve the stability of the insulated pipe and lead to a reduction in material usage (and the resulting decrease in heat conduction).

[0057] In another embodiment of the coupling according to the present invention, the outer tubular element of the coupling plug is provided to be stabilized by additional elements, such as stabilizing rings, which are preferably fixed by shape bonding, most preferably by material bonding. These additional elements are preferably positioned at selected locations along the outer tubular element of the coupling plug. These additional elements can contribute to appropriately controlling or mitigating buckling behavior. These additional elements are preferably made of plastic, preferably fiber-reinforced plastic, most preferably G10 in the warm region, and steel, preferably austenitic steel, in the cold region, and can be joined / fixed by material bonding. However, in order to enjoy the benefits of parts commonality, this embodiment may also be limited to (identical) specifications only.

[0058] This method provides the following further advantages over the prior art, particularly in the first variation of the present invention: a lightweight structure due to reduced material usage, improved buckling resistance, position-independent installation, and reduced heat input. Improved thermal separation also allows for shorter structural lengths than the prior art.

[0059] In another development of the coupling according to the first variation of the present invention, the section in which the first external piping element is structured and formed is provided to coincide axially with the section of the drive element in which the drive element is formed as a smooth tube, and vice versa.

[0060] In this way, the first external piping element and the drive element complement each other geometrically, which can contribute to a reduction in size.

[0061] In another development of the coupling according to the first variation of the present invention, the drive element is provided to have an externally accessible radial projection, preferably having a regular hexagonal shape.

[0062] In this way, the required rotational action can be achieved as easily as possible using standard tools.

[0063] In another development of the coupling according to the first variation of the present invention, the drive element is connected to or can be connected to the coupling plug via a radial projection, preferably using a first clamp.

[0064] This is a simple and proven connection method that can be implemented without incurring significant costs.

[0065] In another development of the coupling according to the first variation of the present invention, the drive element is provided to have an external threaded section.

[0066] This threaded section allows for the attachment of further components of the coupling, which will be discussed later.

[0067] In another development of the coupling according to the first variation of the present invention, a threaded component is screwed into or can be screwed into the threaded section, particularly in the case of a lock nut, until it strikes a coupling socket (as a pressure stop).

[0068] In this way, a simple method is obtained for fixing the coupling socket and the threaded component (and the coupling plug through them) to each other in the axial direction and compensating for tolerances.

[0069] In another development of the coupling according to the first variation of the present invention, the drive element is connected to or connectable to the coupling socket via a threaded component, preferably using a second clamp, and is configured to function as a tension anchor.

[0070] This is a simple and proven connection method that can be implemented without incurring significant (cost) burdens.

[0071] Below, a specific advantageous development of the second variation of the coupling according to the present invention, which has already been mentioned, will be described in detail. This second variation is based on the known solution described in German Patent Application Publication No. 102022110880.

[0072] In a second variation of the coupling according to the present invention, the drive element comprises a first annular external connecting component and a second annular internal connecting component, which are arranged concentrically to form a first engagement structure and are connected in a torsionally rigid manner using a first grooved membrane disc extending radially. The first grooved membrane disc may be fixed to the two connecting components, in particular by material bonding.

[0073] The term "with torsional rigidity" in this case and below means that torque can be transmitted using the relevant connection (or appropriately formed component, such as the grooved membrane disc mentioned above).

[0074] Grooved membrane discs, on the one hand, provide effective thermal isolation of two connecting components without requiring a large axial space. Concentric connecting components can contribute to achieving particularly good and reliable connections. Furthermore, grooved membrane discs enable torque transmission, which will be discussed in more detail later.

[0075] In the second variation, the "hot end" and "cold end" are typically located in at least a nearly common axial position.

[0076] In a second variation of the coupling according to the present invention, the coupling socket has a first connection structure to a second external piping element and a second connection structure to a second internal piping element, and these connection structures are arranged to together form a second engagement structure.

[0077] In this way, by combining it with the concentric connecting components described above, a particularly good and reliable connection can be obtained.

[0078] In a second variation of the coupling according to the present invention, the first and second engagement structures are formed like bayonet locks and are arranged to interact accordingly. Preferably, the first connection structure can interact with the first connecting component, and the second connection structure can interact with the second connecting component.

[0079] Bayonet locks are well known to those skilled in the art. In this context, bayonet locks are advantageous in that they allow the intended axial motion to be achieved with only a quantitatively small (i.e., limited circumferential) rotational movement.

[0080] In a second variation of the coupling according to the present invention, the coupling socket is provided to have a radially extending second grooved membrane disc that connects a second external piping element and a second internal piping element and is morphologically coupled to the first grooved membrane disc.

[0081] In this context, the term "by shape coupling" means that, when the coupling is closed, the first grooved membrane disk and the second grooved membrane disk are perfectly aligned and overlapping each other (i.e., their peaks and valleys can interlock).

[0082] The second grooved membrane disc may be provided, in particular, in the region of the coupling socket, to seal the radial free space between the second external piping element and the second internal piping element from the surroundings, thereby enabling vacuuming, which can improve thermal insulation.

[0083] In a second variation of the coupling based on the present invention, the second grooved membrane disc is provided to be supported axially on its back surface.

[0084] This increases resistance to ambient pressure after vacuuming. "Back side" refers to the opposite side of the coupling point.

[0085] In a second variation of the coupling based on the present invention, the first grooved membrane disc and the second grooved membrane disc are arranged to have different dimensions in the radial direction.

[0086] This allows for the use of different (radial) dimensions of piping elements and connecting components in the plug and socket area.

[0087] In a second variation of the coupling according to the present invention, the coupling plug is provided to have a radially extending third grooved membrane disc that connects a first external piping element and a first internal piping element and is morphologically coupled to the first grooved membrane disc and the second grooved membrane disc.

[0088] In this context, the term "by shape coupling" means that, especially when the coupling is closed, the first grooved membrane disk, the second grooved membrane disk, and the third grooved membrane disk are perfectly aligned and overlapping with each other (i.e., their peaks and valleys can interlock).

[0089] The third grooved membrane disc may be provided, in particular, in the region of the coupling plug, to seal the radial free space between the first external piping element and the first internal piping element from the surroundings, thereby enabling vacuuming, which can improve thermal insulation.

[0090] In a second variation of the coupling based on the present invention, a third grooved membrane disc is provided to be supported axially on its back side. Here again, "back side" refers to the opposite side of the coupling.

[0091] This improves resistance to ambient pressure after vacuuming.

[0092] In a second variation of the coupling based on the present invention, the first grooved membrane disc and the third grooved membrane disc are arranged to have the same dimensions in the radial direction.

[0093] This results in improved stability, which is possible because the two grooved membrane discs mentioned above are located on the same component (plug).

[0094] The first grooved membrane disc is preferably positioned between the second and third grooved membrane discs when the coupling is assembled, and in this case, the two grooved membrane discs are each supported axially from the outside.

[0095] Further features and advantages of the present invention will become apparent from the following description of embodiments with reference to the drawings. [Brief explanation of the drawing]

[0096] [Figure 1] This is a diagram of the individual components of the coupling according to the present invention, in the first variation. [Figure 2] Figure 1 is a longitudinal cross-sectional view of the main components of the coupling. [Figure 3] This is a longitudinal cross-sectional view of the coupling shown in Figure 1 in its assembled state. [Figure 4] This is a longitudinal cross-sectional view of the coupling according to the present invention in an open state, representing a second variation. [Figure 5] This is a diagram showing the coupling in the closed position as shown in Figure 4. [Figure 6] Figure 4 is a detailed view of the coupling socket according to the embodiment shown. [Figure 7] Figure 4 is a detailed view of the coupling plug according to the embodiment shown. [Figure 8] This is a partial cross-sectional view of a coupling according to the present invention in another embodiment. [Modes for carrying out the invention]

[0097] In all diagrams, identical elements or elements that function similarly are given the same reference numerals. The terms "pipe element" and "piping element" are used interchangeably.

[0098] Figure 1 shows an exploded view of the individual components of a coupling 1 according to the present invention, a first variation having a longitudinal axis L. Reference numeral 2 denotes a coupling plug (plug), and reference numeral 3 denotes a coupling socket (socket). A tubular drive element 4 is positioned between them, and separately, reference numeral 36 is also used below. Furthermore, coupling 1 includes two clamps 5, 6, two centering elements 7, 8, a threaded component 9, and two seals (seal rings) 10, 11. All of these elements and their interactions will be described in more detail below.

[0099] The plug 2 includes two coaxial tube elements, namely an internal (medium transport) tube element 13 and an external tube element 14, starting from its front insertion end 12, according to part diagram a) of Figure 2, i.e., Figure 2a). The external tube element 14 is formed as a partially structured tube element and, accordingly, has a non-smooth cylindrical appearance over most of its longitudinal direction. In particular, over most of its longitudinal extension, it is formed as a "bulbed pipe" with multiple identical annular bulges 15, with only one of the bulges being explicitly referenced. This allows the tube element 14 to be made lighter and thinner while maintaining equivalent or improved (pressure) stability. Preferably, the external tube element 14 of the coupling plug 2 is manufactured by forming, preferably by internal high-pressure deformation, or most preferably by bellows pressing.

[0100] At the end 16 (the so-called "warm end"), the outer tube element 14 is radially expanded, and this region does not have a bulge. In the transition region between the bulge 15 and the expanded end 16, a raised portion 17 with a roughly triangular cross-section is provided on the outside, which will be described in detail later.

[0101] A first terminal element 19 is positioned at the other end 18 (the so-called "cold end"), which fluidly connects the inner tube element 13 and the outer tube element 14, preferably by material bonding. The terminal element 19 has a front end face 19a with an inner circumferential projection 19b. A retaining ring-shaped projection 21 is positioned in the circumferential groove 20 of the terminal element 19. Reference numeral 22 denotes "multilayer insulation" (MLI), i.e., laminated insulation material, which is positioned between the inner tube element 13 and the outer tube element 14. Laminated insulation material is usually formed in the form of multiple layers of highly (radiative) reflective foil, as is well known to those skilled in the art.

[0102] Plug 3, according to part diagram b) of Figure 2, i.e., Figure 2b), similarly includes two coaxial tubular elements, namely an internal tubular element 23 and an external tubular element 24, between which again is “multilayer insulation” (MLI), i.e., laminated insulation material 25. The two coaxial tubular elements 23 and 24 of sleeve 3 are fluid-tight, preferably by material bonding, at their end 26 (reference numeral 16, corresponding to the “warm end”) via a second terminal element 27. The second terminal element 27, reference numeral 28, has a shape formed mirror-image to the triangular protrusion 17 of plug 2. The internal tubular element 23 of socket 3 has a tapered cross-section at its free end (right in Figure 2b) and has a (medium transport) tubular extension 29 connected to the rest of the internal tubular element 23 of socket 3 to guide the fluid, the diameter of which matches the diameter of the internal (medium transport) tubular element 13 of plug 2. The pipe extension 29 of plug 2 and the internal pipe element 13 are connected as fluidly tightly as possible using a seal (not shown in Figure 2), which will be described in more detail below.

[0103] In the transition region 30 from the internal tube element 23 to the tube extension 29, the socket 3 has an annular tapered portion 31 which is preferably formed by material bonding with the internal tube element 23 and integrally formed with the tube extension 29, the tapered portion 31 which includes an axial projection 32 with a male thread 33, a structured radial surface 34, and a recess 35 in the transition region between the radial surface 34 and the tube extension 29.

[0104] Figure 2c), part diagram c), shows an additional drive element 36, denoted by reference numeral 4 in Figure 1, which is positioned radially between the plug 2 and the socket 3, as will be shown more clearly below with reference to Figure 3. The drive element 36 is formed in a tubular shape overall and has a smooth cylindrical portion 37 and an annular corrugated portion 38. The smooth cylindrical portion 37 has a longitudinal dimension corresponding to the structural portion of the tube element 14, while the annular corrugated portion 38 has a longitudinal dimension corresponding to the smooth cylindrical "remaining portion" of the tube element 14. The end of the annular corrugated portion 38 is followed (by material bonding) by an annular component 39 with a female thread 40. At the other end, the drive element 36 has a chamfered radial projection 41 (preferably with an external hexagonal profile), a male thread 42, and two circumferential grooves 43, 44 for accommodating the seal rings 10, 11 in Figure 1.

[0105] Figure 3 shows the assembled coupling 1. For clarity, not all elements are newly labeled. To seal the plug 2 and socket 3 at the cold end 18, the drive element 36 is inserted into the socket 3, and the plug 2 is inserted into the drive element 36 on its side. When the drive element 36 rotates about its longitudinal axis L and is screwed into the male thread 33 (see Figure 2) of the socket 3 by its female thread 40 (see Figure 2) (this corresponds to embodiment a according to the present invention), the plug 2 is axially driven by the retaining ring 21 (see Figure 2), and this movement continues until the projection 19b of the plug 2 abuts against the end of the recess 35 of the socket 3. In other words, when the drive element 36 reaches the retaining ring 21, the drive element 36 and the plug 2 are consequently firmly connected in the axial direction. As a result, a seal chamber 45 with a clearly defined (axial) dimension A is formed between the end face 19a of the plug 2 and the radial face 34 of the socket 3, into which a seal (seal ring) 46 is inserted, providing a more reliable seal at the cold end 18, while simultaneously allowing the drive element 36 to be comfortably (remotely) operated from the hot end 16.

[0106] To ensure a secure connection at the hot end 16, the plug 2 has an external protrusion 17 with a roughly triangular or conical cross-section, as previously mentioned (see Figure 2), to which the drive element 36 is in close contact with its projection 41 (see Figure 2). This area is secured by a clamp 5. Furthermore, the threaded component 9 is screwed onto the male thread 42 of the drive element 36, like a lock nut, until it contacts the projection 28 of the socket 3. Here again, it is secured by a clamp 6.

[0107] Therefore, in the illustrated coupling 1, after the first engagement structure (particularly the female thread 40 of the drive element 36, see Figure 2) and the second engagement structure (particularly the male thread 33 of the socket 3, see Figure 2) are properly engaged, an overlapping region is created in the axial direction, and a screw connection is formed between the drive element 36 and the coupling socket 3 in this region. The coupling plug 2 is axially engaged between the drive element 36 and the second internal piping element 23 or the retractable portion 31 in this overlapping region by the radially advancing projection 21 (see Figure 2), so when the screw connection is tightened, the coupling plug 2 is movable or moves in the axial direction toward the radial surface 34 of the second internal piping element 23 or the retractable portion 31.

[0108] Clamp (V-board clamp) 5 is used to detachably connect plug 2 to drive elements 4 and 36, or clamp (V-board clamp) 6 is used to detachably connect drive element 4 or 36 to socket 3. Reference numerals 7 and 8 refer to the centering elements or stabilizing elements already described above. These stabilizing elements 7 and 8 are used to center the inner tube element 13 within the outer tube element 14 in the region of the expanded end of plug 2 or the region of the tube extension 29 within the outer tube element 24. These are preferably made of a material with low thermal conductivity, which is vacuum resistant (no gas release), preferably fiber-reinforced plastic, most preferably glass fiber-reinforced plastic, such as G10.

[0109] Figure 3 shows the coupling 1 in the connected state, as previously mentioned. In this state, the coupling socket 3 and the coupling plug 2 are detachably connected to each other in the region of their outer tube elements 14 or 24 (using clamps 5, 6 and via drive elements 4 or 36) by a first connection at the hot end 16. Furthermore, in the connected state, the other cold end 18 is sealed by a seal 46 over the joint gap in the region of the inner tube elements 13 or 23, 29 between the coupling socket 3 and the coupling plug 2.

[0110] As can be seen in Figure 3, the bulging portion 6 of the pipe element 14 has a symmetrical configuration with respect to a plane perpendicular to the longitudinal axis L, passing through the vertex (not shown) of one of the bulges 15 in question, in a cross-section along the longitudinal axis L of the coupling 1. Furthermore, the bulging portion 15 curves continuously in the direction of the internal pipe element 13 of the coupling plug 2, that is, it has a convex shape with respect to the longitudinal axis L.

[0111] The outer tube element 14 of the coupling plug 2 has a bulge 15 that contacts the inside of the smooth cylindrical portion of the drive element 36. To achieve this, the outer tube element 14 of the coupling plug 2 can be preloaded axially during the coupling process so that the bulge 15 is formed radially outward, thereby closing the gap, particularly the annular gap, between the outer tube element 14 of the coupling plug 2 and the drive element 36. In this way, annular hollows 47 are created along the coupling 1, and these annular hollows 47 prevent the cryogenic fluid from reaching the "warm" seal elements 10 and 11 and damaging them as much as possible. In any case, the annular gap remaining between elements 14 and 36 works to efficiently form an insulating gas layer as the invading cryogenic fluid evaporates, thereby preventing further heat input from the outside.

[0112] Although not shown in the figure, an additional local sealing element insert may be placed between the outer tube element 14 and the drive element 36 of the coupling plug 2, in at least a portion of the bulging portion 15, and this sealing element insert is made of metal, preferably indium.

[0113] Figures 4-7 show alternative embodiments of coupling 1' in the "warm" connection and drive element embodiment, which are clearly different from the variations in Figures 1-3.

[0114] Figure 4 shows coupling 1' in the open state. Basically, we will only go into detail about the most important differences from the first embodiment.

[0115] The coupling 1' includes a drive element 48 in the area of ​​the plug 2, which has a first annular external connecting part 49 having a radial projection 49a preferably with a hexagonal profile, and a second annular internal connecting part 50. These connecting parts are arranged concentrically and together form a first plug-side engagement structure, which is in particular formed like a bayonet lock. The connecting parts 49 and 50 are connected by a first grooved membrane disc 51 that extends radially. This first grooved membrane disc 51 is fixed to the two connecting parts 49 and 50 by material bonding. This grooved membrane disc 51 allows torque to be transmitted from the first connecting part 49 to the second connecting part 50 using the drive element 48, and its effective radial length ensures relatively high heat resistance. The external connecting component 49 is fixed to a plurality of stepped pipe components 14a via retaining rings 49b, the pipe components 14a being axial extensions (connected by material bonding) of the first external pipe element 14.

[0116] Accordingly, in coupling 1' shown in Figure 4, the coupling socket 3 has a first connection structure 52 to a second external piping element (indicated only by reference numeral 24, see Figure 5) and a second connection structure 53 to a second internal piping element 23, and these connection structures are arranged to form a second socket-side engagement structure.

[0117] As already noted, in this variation, the first plug-side engagement structure and the second socket-side engagement structure are formed like a bayonet lock and interact accordingly, with the first connecting structure 52 interacting with the first connecting component 49 and the second connecting structure 53 interacting with the second connecting component 50. Since bayonet locks are well known to those skilled in the art, their exact structure will not be mentioned here. In this case, when the bayonet lock closes due to the corresponding (relative) rotational movement of the plug 2 and socket 3, the coupling 1' is not only securely locked, but the plug 2 and socket 3 also move relative to each other axially for sealing purposes. This will be explained in more detail later.

[0118] First, it should be noted that in coupling 1', the coupling socket 3 has a radially extending second grooved membrane disc 54 that connects the second external piping element 24 and the second internal piping element 23 via connecting structures 52 and 53, with the intermediate space or free space 55 between them being evacuable and positioned on the first grooved membrane disc 51 by shape coupling. This means that, in this case, when the plug 2 and socket 3 are coaxially aligned along the longitudinal axis and coupled axially (see Figure 5 below), the grooved membrane discs 51 and 54 interlock with each other at their peaks and valleys.

[0119] According to Figure 4, in the case of plug 2, the first outer tube element 14 and the first inner tube element 13 are mostly formed as annular corrugated hoses. Between them are an intermediate space or free space 56, an MLI 22, and a braided sleeve 57 that surrounds the inner tube element 13 to stabilize it. The free space 56 is evacuable via a connecting piece 57. Reference numeral 58 denotes a suction device.

[0120] For this purpose, the coupling 1' or coupling plug 2 further has a radially extending third grooved membrane disc 59 which connects the first external piping element 14 in the region of the extension tube component 14a and the first internal piping element 13 in the region of the terminal element 19 by material bonding, so that the intermediate space or free space 56 can be evacuated. In this case, the third grooved membrane disc 59 is positioned by shape bonding, in particular, to the first grooved membrane disc 51 and (see Figure 5 if the coupling 1' is closed) to the second grooved membrane disc 54, as defined above. In Figure 4, the grooved membrane discs 51 and 59 are already in close contact with each other by shape bonding and are therefore not recognizable as separate entities.

[0121] To improve resistance to ambient pressure when vacuuming the intermediate spaces 55, 56, the second grooved membrane disc 54 and the third grooved membrane disc 59 are each supported axially on their rear sides, and for this purpose, each is provided with at least one corresponding support element 60, 61, as shown in the figure.

[0122] As shown in the diagram, the first grooved membrane disc 51 and the second grooved membrane disc 54 have different dimensions in the radial direction, while preferably the first grooved membrane disc 51 and the third grooved membrane disc 59 have the same dimensions in the radial direction.

[0123] The so-called "cold end" 18 is located on the inside, according to the embodiment in Figure 4. The terminal element 19, which has already been mentioned, is also located here, and it fluidly connects the inner tube element 13 and the outer tube element 14 together by material bonding, including the extension 14a (via the grooved membrane disc 59). The terminal element 19 has a front end face 19a with an inner circumferential projection 19b. Reference numeral 46 indicates a seal. A retaining ring 21 is positioned in the circumferential groove 20 of the terminal element 19, which interacts with the spring 62 and the circumferential projection 63 to ensure that the connecting component 50 is securely held in the terminal element 19.

[0124] Similar to the embodiment of socket 3 shown in Figure 2, Figure 4 also includes an annular component 31 having a radial surface 34 and a recess 35, which interacts with the plug 2 when the terminal element 19 and the annular component 31 come into contact at the projection 19b in the region of the recess 35, providing a sealing chamber of defined (axial) dimensions. This is shown in Figure 5.

[0125] Figure 5 shows the coupling 1' of Figure 4 in the closed state. For ease of viewing, not all elements are explicitly shown again (see Figure 4). The engaging structure interacts like a bayonet lock, as described in detail above. The three grooved membrane discs 51, 54, and 59 are all tightly attached to each other by shape coupling. The seal chamber 45 has an axially defined dimension A, as described above using Figure 3. Here again, the connection at the cold end 18 is tightened by torque applied to the drive element 48 at the hot end 16, and in particular by acting on element 49 (reference numeral 49a), causing the bayonet lock to close and, in particular, the relative axial motion of parts 19 and 31 to form the described seal at the cold end 18.

[0126] Figure 6 shows a detailed perspective view of socket 3, illustrating possible embodiments of connection structures 52, 53 such as bayonet locks, as well as possible embodiments of associated grooved membrane discs 54.

[0127] Figure 7 similarly shows a detailed perspective view of the plug 2, revealing possible embodiments of the connection structure, such as complementary bayonet-type locks in the connecting parts 49 and 50, as well as possible embodiments of the associated grooved membrane disc 51 used for torque transmission. The torque acts accordingly at the position indicated by reference numeral 49a. Element 49 has, in particular, a recess 49c for this purpose. Alternatively, embodiments with a hexagonal contour are also conceivable in this region.

[0128] Figure 8 shows a modified example corresponding to embodiment b) of the present invention, which partially illustrates the embodiments shown in Figures 1-3. Here, we will only discuss in detail the main differences from the embodiments based on Figures 1-3 that have already been described.

[0129] According to Figure 8, the male thread 40, which forms part of the engagement structure described, is located on the plug 2, not the socket 3. An annular component 39 with a female thread 40 is attached (by material bonding) to the end of the annular corrugated portion 36 of the drive element 36. In contrast, the retaining ring 21 is located between the annular component 39 and the retracted portion (end element) 31 of the socket 3, not on the plug 2.

[0130] In this way, the socket 3 and the drive element 36 can be pre-installed. After the first engagement structure and the second engagement structure are properly engaged, the axial relative motion of the coupling plug 2 and the coupling socket 3 described above is again caused by rotational motion applied to the drive element 36 from the outside, about the common longitudinal axis L of the piping elements, thereby forming or making possible a fluid-tight connection.

[0131] Furthermore, in Figure 8, unlike the embodiments shown in Figures 1-3, it can be seen that here the drive element 36 is implemented in this way in a partial section, rather than the plug 2 (i.e., the insulation tube "male", element 14) being implemented as a valved pipe (to the left of the corrugated section 38). As already mentioned, the main advantage of a valved pipe is improved resistance to buckling. However, in this invention, no pressure is applied to the insulated pipe 14 because the cold seal 46 effectively seals it. Therefore, it is also possible to place the guide valve inside the drive element 36. This is also basically valid for the embodiments shown in Figures 1-3.

Claims

1. A cryogenic piping coupling (1, 1') comprising a coupling socket (3) and a coupling plug (2), The coupling plug (2) has a first internal piping element (13) for transporting a medium and a first external piping element (14) that surrounds the first internal piping element (13) coaxially at a radial distance, and a first free space (56) that can be evacuated is formed between the first piping elements (13, 14). The coupling socket (3) has a second internal piping element (23, 29) and a second external piping element (24) that surrounds the second internal piping element (23, 29) coaxially at a radial distance, and a second free space (55) that can be evacuated is formed between the second piping elements (23, 24). The first internal piping element (13) is detachably connected to or connectable to the second internal piping elements (23, 29). The first external piping element (14) is detachably connected to or connectable to the second external piping element (24). In coupling (1,1'), The drive elements (4, 36; 48) connected to or connectable to the coupling plug (2) have a first engagement structure formed complementary to a second engagement structure in the coupling socket (3), or b) a first engagement structure formed complementary to a second engagement structure in the coupling plug (2). After the first engagement structure and the second engagement structure are properly engaged, rotational motion applied externally to the drive element (4, 36; 48) about the common longitudinal axis (L) of the piping elements (13, 14, 23, 24) causes, or may cause, axial relative motion between the coupling plug (2) and the coupling socket (3), thereby forming, or making possible, a fluid-tight connection between the first internal piping element (13) and the second internal piping elements (23, 29). A coupling (1,1') characterized by the following:

2. The coupling (1, 1') according to claim 1, wherein a seal chamber (45) of a defined dimension (A) is formed at least axially between the front sides of the connection region between the first internal piping element (13) and the second internal piping elements (23, 29), and a seal (46) is housed within the seal chamber (45).

3. The coupling (1, 1') according to claim 2, wherein the sealing chamber (45) is formed by the two internal piping elements (13, 23) being arranged in close contact.

4. The coupling (1, 1') according to claim 2 or 3, wherein the sealing chamber (45) is formed between the terminal element (19) at the end of the coupling plug (2) and the terminal elements (29, 31) at the end of the coupling socket (3), preferably as a circumferential recess of the terminal element at the end of the coupling socket (3) or the coupling plug (2).

5. The coupling (1, 1') according to claim 4, wherein the axial dimension of the seal chamber (45) is limited by the amount of axial protrusion of the axial projection (19b) of the terminal element (19) at the end of the coupling plug (2) beyond the other terminal elements (19) at the end of the coupling plug (2), or by the amount of axial protrusion of the axial projection of the terminal element at the end of the coupling socket (3) beyond the other terminal elements at the end of the coupling socket (3).

6. The coupling (1) according to any one of claims 1 to 5, wherein the drive elements (4, 36; 48) are formed to have torsional rigidity, particularly using a grooved membrane disc (51) or as additional piping elements (4, 36), and are preferably formed at least partially as a corrugated hose, most preferably as an annular corrugated hose (38) or bellows.

7. The coupling (1) according to any one of claims 1 to 6, wherein the engagement structure is formed as a complementary screw structure, preferably as a female thread (40) on the drive element (4, 36) and as a male thread (33) on the coupling socket (3), most preferably on the second internal piping element (23, 29), or vice versa.

8. The coupling (1) according to claim 7, wherein after the first engagement structure and the second engagement structure are properly engaged, an overlapping region is created in the axial direction, in which a screw connection is formed between the drive elements (4, 36) and the coupling socket (3), and the coupling plug (2) is axially engaged between the drive elements (4, 36) and the second internal piping elements (23, 29) in the overlapping region by radially moving projections (21), so when the screw connection is tightened, the coupling plug (2) is movable in the axial direction toward the second internal piping elements (23, 29).

9. The coupling (1) according to claim 8, wherein the accompanying projection (21) is formed as a retaining ring or snap ring partially positioned in the circumferential groove (20) of the coupling plug (2).

10. The coupling (1) according to any one of claims 7 to 9, wherein the drive elements (4, 36) extend axially from the "hot end" (16, 26) where the first external piping element (14) and the second external piping element (24) are connected to each other, to the "cold end" (18) where the first internal piping element (13) and the second internal piping elements (23, 29) are connected to each other, and the drive elements (4, 36) are preferably arranged radially between the coupling socket (3) and the coupling plug (2).

11. The coupling (1) according to any one of claims 7 to 10, wherein the first external tube element (14) or the drive element (4, 36) is formed as a structured tube element in at least one subsection, and in the subsection has an external contour different from a smooth cylindrical shape, preferably the first external tube element (14) has a plurality of annular bulges (15) in the subsection, or the first external tube element (14) has a plurality of individual local bulges in the subsection, or the first external tube element (14) has a honeycomb shape in its external contour in the subsection.

12. The coupling (1) according to claim 11, wherein a portion of the external piping element (14) coincides axially with a portion in which the drive elements (4, 36) are formed as a smooth pipe (37), or vice versa.

13. The coupling (1) according to any one of claims 7 to 12, wherein the drive element (4, 36) preferably has a radial projection (41) that is accessible from the outside and has a regular hexagonal shape.

14. The coupling (1) according to claim 13, wherein the drive elements (4, 36) are connected to or can be connected to the coupling plug (2) via the radial projection (41), preferably using a first clamp (5).

15. The coupling (1) according to any one of claims 7 to 14, wherein the drive element (4, 36) has an external threaded section (42).

16. The coupling (1) according to claim 15, wherein a threaded component (9) is screwed into the threaded section (42), or can be screwed in, particularly in the form of a lock nut, until it strikes the coupling socket (3).

17. The coupling (1) according to claim 16, wherein the drive elements (4, 36) are connected to or can be connected to the coupling socket (3) via the screw-in component (9), preferably using a second clamp (6).

18. The coupling (1') according to any one of claims 1 to 6, wherein the drive element (48) comprises a first annular external connecting component (49) and a second annular internal connecting component (50), the connecting components being connected by a first grooved membrane disc (51) which is arranged concentrically and together forms the first engagement structure and extends radially, and preferably the first grooved membrane disc (51) is fixed to the two connecting components (49, 50) by material bonding.

19. The coupling (1') according to claim 18, wherein the coupling socket (3) has a first connection structure (52) in the second external piping element (24) and a second connection structure (53) in the second internal piping element (23), and the connection structures together form the second engagement structure.

20. The coupling (1') according to claim 18, wherein the first engagement structure and the second engagement structure are formed and interact with each other in the manner of a bayonet lock, and in this case, preferably referring to claim 19, the first connecting structure (52) interacts with the first connecting component (49) and the second connecting structure (53) interacts with the second connecting component (50).

21. The coupling (1') according to any one of claims 18 to 20, wherein the coupling socket (3) has a second grooved membrane disc (54) extending in the radial direction, the second grooved membrane disc (54) connects the second external piping element (24) and the second internal piping element (23), and is arranged to the first grooved membrane disc (51) by shape coupling.

22. The coupling (1') according to claim 21, wherein the second grooved membrane disc (54) is supported axially on its back surface.

23. The coupling (1') according to claim 21 or 22, wherein the first grooved membrane disc (51) and the second grooved membrane disc (54) have different dimensions in the radial direction.

24. The coupling plug (2) has a radially extending third grooved membrane disc (59), the third grooved membrane disc (59) connecting the first external piping element (14) and the first internal piping element (13), and is arranged to the first grooved membrane disc (51) and the second grooved membrane disc (54) by shape coupling, according to any one of claims 18 to 23.

25. The coupling (1') according to claim 24, wherein the third grooved membrane disc (59) is supported axially on its back surface.

26. The coupling (1') according to claim 24 or 25, wherein the first grooved membrane disc (51) and the third grooved membrane disc (59) have the same dimensions in the radial direction.

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