Connection fitting for a cryogenic conduit

Abstract

A connection fitting (2, 3) for a cryogenic conduit (5), which is guided through an evacuable tube (6) with circumferential clearance for vacuum insulation, is characterized in that the connection fitting (2, 3) has an inner fitting (19) and an outer fitting (20) surrounding it at a distance approximately coaxially, wherein the inner fitting (19) can be connected to the cryogenic conduit end (7, 8) and the outer fitting (20) to the tube end (9, 10), wherein the inner and outer fittings (19, 20) are connected to each other via a ring structure (21), and wherein the ring structure (21) contains a bellows section (35).

Description

[0001] The present invention relates to a connection piece for a cryogenic line which is guided through an evacuable pipe with circumferential clearance for the purpose of vacuum insulation.

[0002] Cryogenic fluids such as liquefied hydrogen or liquefied natural gas (LNG) are frequently used as high-energy-density fuels for powering vehicles, such as trucks or buses. The cryogenic fluids are stored in cryogenic tanks, which are mounted on the chassis on either side of the vehicle. To easily fill such dual tanks from one side of the vehicle, cryogenic lines are required between the tanks or their filling and withdrawal fittings, as well as connecting pieces for these cryogenic lines.

[0003] To maintain the cryogenic fluids' lowest temperatures, e.g., less than -252 °C for liquid hydrogen or less than -161 °C for LNG, the cryogenic lines and their connecting fittings must be excellently thermally insulated. Double-walled constructions with vacuum insulation are typically used for this purpose, especially for liquid hydrogen. However, the use of such constructions on a vehicle chassis presents an additional challenge, as the cryogenic lines and connecting fittings must be able to withstand vibrations and torsions of the vehicle chassis, which result in significant changes in the position of the connected components.

[0004] The invention aims to create a connection piece for a cryogenic line which meets these requirements.

[0005] This objective is achieved by means of a connecting piece for a cryogenic line which is guided through an evacuable pipe with circumferential clearance for the purpose of vacuum insulation, which connecting piece is characterized in that the connecting piece has an inner piece and an outer piece which surrounds the inner piece approximately coaxially at a distance therefrom, wherein the inner piece is connectable to the cryogenic line end and the outer piece is connectable to the pipe end, wherein the inner and outer pieces are connected to one another via a ring structure, and wherein the ring structure contains a bellows section.

[0006] The free end of the inner nozzle can be used for the cryogenic fluid connection of the component to be connected to the connection nozzle, and the free end of the outer nozzle creates a surrounding annular space opposite the inner nozzle, which can again be used for vacuum insulation. Furthermore, the outer nozzle can assume the main load of the mechanical connection to the connected component, thus relieving the inner nozzle, which serves to connect the cryogenic fluid. The bellows section compensates for any movements or misalignments between the inner and outer nozzles that can occur when connecting the respective connection nozzle to the respective component. The connection nozzle of the invention thus creates a vacuum-insulated double-wall structure that can follow any relative movements of the connected component and thus also withstand strong vibrations and torsions of a vehicle without damage.This ensures complete vacuum thermal insulation of the cryofluid at all times.

[0007] It is particularly advantageous if the ring structure tightly connects the inner and outer nozzles. This separates the annular space between the inner and outer nozzles, on the one hand, and the space between the cryogenic line and the pipe, on the other, so that they can be insulated separately, especially evacuated. Alternatively, the ring structure could connect the inner and outer nozzles in a gas-permeable manner, so that the annular space between the inner and outer nozzles, on the one hand, and the space between the cryogenic line and the pipe, on the other, are pressure-connected and can be evacuated together, if desired.

[0008] Preferably, the ring structure is set back from the free ends of the inner and outer nozzles. This makes the free ends of the inner and outer nozzles more easily accessible for connection.

[0009] The bellows section can be located at any suitable location in the ring structure, for example, in the form of a zigzag-folded annular disc that fills the annular space between the inner and outer nozzles. In a particularly advantageous embodiment of the invention, the envelope of the bellows section is approximately cylindrical and runs coaxially and at a distance from the inner and outer nozzles. This allows for a particularly large range of motion between the inner and outer nozzles.

[0010] In all of the above-mentioned embodiments, the outer connector is optionally provided with a bellows collar, via which the pipe end can be connected to the outer connector. This allows the connected pipe to move relative to the cryogenic line contained therein. The latter can be designed, for example, as a flexible hose that can stretch when the bellows collar is pulled apart and bend when the bellows collar is contracted. A cryogenic line equipped with the connecting connector according to the invention can thus also follow any changes in the position or distance of the connected components.

[0011] It is particularly advantageous if the bellows seal is made of metal, preferably stainless steel. This gives the bellows seal a resilient rest position from which it can be expanded and contracted, while also providing high gas tightness and elongation at break.

[0012] According to a further preferred feature of the invention, the ring structure is connected to the outer connector via a rotationally fixed coupling so that it can be axially retracted and extended. This allows the outer connector to be pushed back, for example, to expose the free end of the inner connector, so that this can be connected to the cryogenic fluid connection in a first step. Subsequently, the outer connector can be pushed forward again, for example, to mechanically secure it to the component providing the cryogenic fluid connection.

[0013] The coupling preferably has an external gear ring on one of the two parts, the ring structure and the outer connecting piece, and an internal gear ring that can be engaged with the external gear ring on the other of the two parts, the ring structure and the outer connecting piece. This allows the rotational position of the rotational fixation of the coupling to be adjusted as desired by selecting the engagement position of the gear rings. For this purpose, the ring structure preferably has an inner shoulder, and the outer connecting piece has an outer shoulder that abuts against it during its outward movement.

[0014] In all embodiments with a coupling, it is also particularly advantageous if the ring structure has an annular recess into which the outer connector can be inserted during its inward movement. A side wall of the recess can then be used, for example, for a cylindrical bellows section running coaxially with the inner and outer connectors. Alternatively, the annular recess can be located between the bellows section and the coupling.

[0015] According to an advantageous feature of the invention, the free ends of the inner and outer nozzles can each have an end flange with a union nut. The inner nozzle can then be screwed to the cryogenic fluid connection of the component to be connected, and the outer nozzle can be screwed to a screw connection of the component surrounding the cryogenic fluid connection to absorb the main mechanical load. The annular space between the inner and outer nozzles is thus simultaneously sealed and can be evacuated for thermal insulation.

[0016] The invention will be explained in more detail below with reference to an embodiment shown in the accompanying drawings. Fig. 1 a connecting line with two connecting pieces according to the invention in a perspective longitudinal section; and Fig. 2 one of the connection pieces of the connecting line from Fig. 1 in a perspective longitudinal section enlarged in detail.

[0017] Fig. 1 shows a connecting line 1 for a cryogenic fluid. The cryogenic fluid can be, for example, hydrogen, which is at least partially liquefied at temperatures of up to -252 °C and below and a pressure of up to 16 bar – or more, depending on the container design – or a comparable cryogenic fluid usable in internal combustion engines or fuel cells, e.g., liquefied natural gas (LNG) with a temperature of up to -161 °C and below. However, the cryogenic fluid can also be a refrigerant, such as liquid nitrogen, which is used to operate the cooling system of refrigerated trucks, e.g., food transporters.

[0018] The connecting line 1 has a connecting piece 2, 3 at each of its two ends, with which it can be connected to a component to be connected, e.g., a fuel tank, a refrigerant container, or a fitting for filling or removing cryogenic fluid from it. For example, the connecting line 1 is used to connect two hydrogen tanks mounted on opposite sides of a truck, allowing them to be filled or emptied together from one side of the vehicle.

[0019] The connecting cable 1 is supported by the components connected via the connecting pieces 2, 3. Alternatively or additionally, it has an anchor 4 on its outside, via which it can be attached, for example, to a vehicle chassis. The connecting cable 1 is thus fixed to the vehicle chassis either at two anchor points, namely the connected components mounted on the vehicle chassis, or at three anchor points, namely the two connected components and the anchor 4.

[0020] The connecting line 1 is an evacuable double-wall construction consisting of an inner cryogenic line in the form of a flexible hose 5 and a rigid pipe 6 surrounding it with circumferential clearance. The ends 7, 8 of the hose 5 are tightly connected to the ends 9, 10 of the pipe 6 via one of the connecting pieces 2, 3. This allows the clearance or gap 11 between the hose 5 and the pipe 6 to be evacuated for the purpose of thermally insulating the hose 5, e.g., via a closable evacuation opening 12 in the pipe 6.

[0021] At least one of the sealed connections between the respective pipe end 9, 10 and the respective connecting piece 2, 3—here both sealed connections—is made via a bellows sleeve 13, 14, which can optionally also be counted as part of the connecting piece 2, 3. The end 15 of the bellows sleeve 13 facing away from the connecting piece 2 is connected to the pipe end 9, and the end 16 of the bellows sleeve 14 facing away from the connecting piece 3 is connected to the pipe end 10. If only one bellows sleeve is used, e.g., between the connecting piece 2 and the pipe end 9, the other pipe end 10 can be sealed directly to the other connecting piece 3.

[0022] The tube 6 and the bellows sleeves 13, 14 can be made of plastic, for example. For resistance to extremely low temperatures, they are made of metal, such as stainless steel or aluminum. The bellows sleeves 13, 14 thus have a resilient rest position between their extended and retracted positions.

[0023] The lengths of the hose 5, the pipe 6 and the bellows cuffs 13, 14 are dimensioned such that in a more extended position of one or both bellows cuffs 13, 14, the hose 5 is less curved, for example, stretched, and in a contracted position of one or both bellows cuffs 13, 14, the hose 5 is more curved. For example, Fig. 1 The rest position of the bellows cuffs 13, 14, in which the hose 5 runs through the pipe 6 in multiple curves. When one or both bellows cuffs 13, 14 are pulled apart, the hose 5 can stretch, and when one or both bellows cuffs 13, 14 are pulled together, it can bend more sharply.

[0024] This allows for the absorption of relative movements between the components connected by the connecting line 1. If the anchor 4 is used as a third anchoring point, one bellows sleeve 13 and the curved hose 5 can compensate for relative movements between the anchor 4 and one component, and the other bellows sleeve 14 and the curved hose 5 can compensate for relative movements between the anchor 4 and the other component.

[0025] The hose 5 is made of a flexible material, for example, plastic or flexible metal. To protect it from abrasion against the inside of the pipe 6 in the event of excessive curvature of the hose 5, the hose 5 is optionally provided with an abrasion-resistant jacket 17. The jacket 17 can be made, for example, from a woven, scrim, knitted, or nonwoven fabric made of glass fibers. A layer 18 made of a thermally insulating material is optionally interposed between the hose 5 and the jacket 17. For example, the layer 18 is formed by an aluminum foil wrapped in several layers around the hose 5, with a thermally insulating fleece wrapped between the layers.

[0026] The structure of one of the connecting pieces 2, 3 is now shown using Fig. 2 for connection piece 2 is explained in detail. The structure of connection piece 3 is analogous.

[0027] According to Fig. 2 The connecting piece 2 comprises an inner piece 19 that can be connected to the hose end 7, and an outer piece 20 that can be connected to the pipe end 9 directly or via the bellows section 13, if present. The inner and outer pieces 19, 20 are connected to one another via a ring structure 21. The ring structure 21 can establish a tight connection between the inner piece 19 and the outer piece 20, whereby the intermediate space 11 can be evacuated separately. Alternatively, the ring structure 21 can be gas-permeable, so that the intermediate space 11 is pressure-connected to the annular space 22 between the inner piece 19 and the outer piece 20 and can be evacuated together with it, if desired.

[0028] The ring structure 21 is set back from the free ends 23, 24 of the inner and outer nozzles 19, 20 toward the pipe 6, so that the ends 23, 24 are freely accessible for the components to be connected, e.g., a vehicle tank or a fitting. For this purpose, the free ends 23, 24 of the inner and outer nozzles 19, 20 each have an end flange 25, 26 with a union nut 27, 28. This allows the inner nozzle 19 to be connected, e.g., to a cryogenic fluid connection, and the outer flange 20 to be connected, e.g., to a load-bearing thread.

[0029] To facilitate the creation of these connections, in particular the screw connections using the union nuts 27, 28, the ring structure 21 can optionally be connected to the outer nozzle 20 via an axially movable coupling 29. The coupling 29 allows inward and outward movement of the outer nozzle 20 relative to the ring structure 21 and the connected inner nozzle 19, e.g., to push back the outer nozzle 20 to expose the end 23 of the inner nozzle 19 in order to screw the inner nozzle 19 to a cryogenic fluid connection using the union nut 27. The outer nozzle 20 is then pushed forward again to fix the outer nozzle 20 to the component to be connected using the union nut 28.

[0030] The coupling 29 comprises a stop that limits the outward movement of the outer nozzle 20. For this purpose, one of the parts, outer nozzle 20 and ring structure 21 (here: the ring structure 21), has an inner shoulder 30, and the other of the parts, outer nozzle 20 and ring structure 21 (here: the outer nozzle 20), has an outer shoulder 31 that abuts against it during the outward movement of the outer nozzle 20.

[0031] The coupling 29 can be rotatable or rotationally fixed. With a rotationally fixed coupling 29, the rotational position of the rotational fixation can be adjustable. For adjustment, for example, the outer socket 20 can have an external gear ring 32 and the ring structure 21 an internal gear ring 33 (or vice versa), which gear rings can mesh with each other and thus achieve the rotational fixation of the coupling 22. By moving the outer socket 20 inward, the gear rings 32, 33 can be disengaged and then the outer socket 20 can be rotated relative to the ring structure 21 in order to select a different rotational fixation position, in which the outer socket 20 will again engage rotationally fixed upon moving outward. For this purpose, the ring structure 21 can have an annular recess 34 into which the outer socket 20 can dip during its inward movement.

[0032] As in Fig. 2As shown, the ring structure 21 can optionally have a bellows section 35 to compensate for relative movements between the inner nozzle 19 and the outer nozzle 20, in particular tilts or offsets between their longitudinal axes. This can be useful to compensate for tolerances between a cryogenic fluid port to which the inner nozzle 19 is connected and an evacuation and load port to which the outer nozzle 20 is connected, or to compensate for any bending movements of the inner nozzle 19 with the hose 5 when it moves. Furthermore, the bellows section 35 extends the heat dissipation path from the cold nozzle 19 to the warmer ring structure 21, thus reducing the heat input into the cold medium.

[0033] The bellows section 35 integrated into the ring structure 21 can, for example - as also the bellows sleeves 13, 14 - have an envelope which is approximately cylindrical and runs coaxially and with radial distances to both the inner nozzle 19 and the outer nozzle 20.

[0034] In the example shown, the annular recess 34 of the ring structure 21 is located between the bellows section 35 and the coupling 29. However, the bellows section 35 could be located at a different location on the ring structure 21.

[0035] A binding agent 36 for hydrogen gas can be arranged in the tube 6, particularly along the hose 5. The binding agent 36 can, for example, be contained in a grid cage 37 provided with gas inlets, which extends approximately in a rod- or bolt-shaped manner next to the hose 5 in the tube 6 over its entire length.

[0036] The invention is not limited to the embodiments shown, but includes all variants, modifications and combinations thereof that fall within the scope of the appended claims.

Claims

1. Connection piece for a cryogenic line, which is guided through an evacuatable pipe with circumferential clearance for the purpose of vacuum insulation, characterized in that the connecting piece (2, 3) has an inner piece (19) and an outer piece (20) which surrounds the latter approximately coaxially at a distance, the inner piece (19) being connectable to the cryogenic line end (7, 8) and the outer piece (20) being connectable to the pipe end (9, 10), the inner and outer pieces (19, 20) being connected to one another via a ring structure (21), and the ring structure (21) containing a bellows section (35).

2. Connection piece according to claim 1, characterized in that the ring structure (21) tightly connects the inner and outer nozzles (19, 20).

3. Connection piece according to claim 1 or 2, characterized in that the ring structure (21) is set back from the free ends (23, 24) of the inner and outer nozzles (19, 20).

4. Connection piece according to one of claims 1 to 3, characterized in thatthe envelope of the bellows section (35) is approximately cylindrical and runs coaxially and at a distance from the inner and outer nozzles (19, 20).

5. Connection piece according to one of claims 1 to 4, characterized in that the outer socket (20) is provided with a bellows sleeve (13, 14) via which the pipe end (9, 10) can be connected to the outer socket (20).

6. Connection piece according to claim 5, characterized in that the bellows sleeve (13, 14) is made of metal, preferably stainless steel.

7. Connection piece according to one of claims 1 to 6, characterized in that the ring structure (21) is connected to the outer nozzle (20) via a rotationally fixed coupling (29) so that it can move axially inwards and outwards.

8. Connection piece according to claim 7, characterized in thatthe coupling (29) has an external gear ring (32) on one of the two parts, the ring structure (21) and the outer socket (20), and an internal gear ring (33) which can be brought into engagement with the external gear ring (32) on the other of the two parts, the ring structure (21) and the outer socket (20).

9. Connection piece according to claim 7 or 8, characterized in that the ring structure (21) has an inner shoulder (30) and the outer socket (20) has an outer shoulder (31) which abuts against it during its outward movement.

10. Connection piece according to one of claims 7 to 9, characterized in that the ring structure (21) has an annular recess (34) into which the outer nozzle (20) can dip during its inward movement.

11. Connection piece according to one of claims 7 to 10, characterized in that the annular recess (34) lies between the bellows section (35) and the coupling (29).

12. Connection piece according to one of claims 1 to 11, characterized in thatthe free ends (23, 24) of the inner and outer sockets (19, 20) each have an end flange (25, 26) with a union nut (27, 28).

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