Aircraft having a refuelling connection for refuelling with a cryogenic fuel

Abstract

The invention relates to an aircraft having a refuelling connection which is fluidically connected to a tank arranged in the aircraft, wherein the refuelling connection and the tank are designed to receive a cryogenic fuel, wherein the refuelling connection comprises a pipe section (7) specially designed for conducting a cryogenic fuel and a coupling (23) which is fixed to an aircraft-fixed structure, wherein the pipe section (7) and / or the coupling (23) has at least two diametrically arranged radially outwardly projecting lug flanges (17, 20), and at least two projecting mounting flanges (18, 21) are provided on the aircraft-fixed structure, on which mounting flanges the pipe section (7) and / or the coupling (23) is fixed to the aircraft by means of the lug flanges (17, 20).

Description

[0001] Lufthansa Technik AG, 22335 Hamburg, DE

[0002] Aircraft with a refueling port for refueling with cryogenic fuel

[0003] The present invention relates to an aircraft with a refueling port for refueling with a cryogenic fuel having the features of the preamble of claim 1.

[0004] Aircraft powered by kerosene usually have their tanks located in the wings, with the refueling ports on the underside of the wings, allowing the aircraft to be refueled from below using a tanker truck and a hose.

[0005] The use of cryogenic fuels, such as liquid hydrogen, presents additional challenges. While the energy density of liquid hydrogen per unit mass is higher than that of kerosene, its energy density per unit volume is four times lower. To compensate for this lower volumetric energy density, hydrogen is stored and refueled in liquid form in aviation, where volume is a critical factor. This liquid state is achieved at a temperature of -253 °C, which corresponds to the boiling point of hydrogen.

[0006] To cool the cryogenic fuel to this low temperature in an energy-efficient manner, a spherical tank would be the ideal shape. However, a spherical tank is not practical in terms of the overall architecture of the aircraft's wings, as it would poorly utilize the available space within the wing, or necessitate a correspondingly small tank. Therefore, other tank shapes and types are required, where, for energy-efficient cooling, the ratio of the external surface area to the tank's volume should be as small as possible. For example, cylindrical tanks with a circular cross-section are suitable.

[0007] Furthermore, refueling the aircraft with cryogenic fuel, such as hydrogen, requires appropriate insulation of the refueling lines and interfaces. An LH2 coupling has proven effective for this purpose, featuring a specifically designed insulation concept with various O-rings and thus specifically designed for a pressure line carrying a cryogenic fluid. Due to the very low temperatures and the large temperature differences with the surrounding environment, the lines, the coupling itself, and the interfaces are subjected to very large differential thermal expansions. These can consequently lead to correspondingly high material stresses if the material is not able to accommodate the differential thermal expansions due to clamping.

[0008] Against this background, the invention is based on the task of providing an aircraft with a refueling port that is designed for improved refueling with a cryogenic fuel.

[0009] To solve the problem, an aircraft with the features of claim 1 is proposed. Further preferred developments can be found in the dependent claims, the figures, and the accompanying description. According to the basic idea of ​​the invention, it is proposed that the tube section and / or the coupling has at least two diametrically arranged, radially outwardly projecting wing flanges, and that at least two projecting retaining flanges are provided on the aircraft-mounted structure, on which the tube section and / or the coupling with the wing flanges is fixedly attached to the aircraft.

[0010] It is further proposed that the wing flanges be attached to the retaining flanges with the same sides facing the circumferential direction of the pipe section and / or the coupling. The pipe section or coupling is thus attached to the retaining flanges by means of the wing flanges such that one wing flange is attached to the underside of a retaining flange and the other wing flange to the top of a retaining flange. The advantage of this solution is that the pipe section or coupling can be placed on the connection in a rotational position relative to its longitudinal axis, and the wing flanges can then be brought into contact with the retaining flanges by a simple rotational movement, and subsequently fastened to them.

[0011] The wing flanges are preferably arranged in pairs, with each pair's sides lying in a common plane. This proposed arrangement of the wing flanges allows the pipe section or coupling to be attached to the retaining flanges with retaining forces that are as symmetrical as possible about the central axis of the pipe section or coupling running between the wing flanges, and particularly preferably point-symmetrical about the center point of the pipe section's or coupling's cross-section. If the wing flanges are attached on the same sides circumferentially, then the underside of one wing flange and the top side of the other wing flange form the plane. If the wing flanges are attached on different sides circumferentially, then the top and / or underside of the wing flanges form the plane.

[0012] It is further proposed that the wing flanges be welded to the pipe section and / or the coupling. The pipe section or coupling can thus be prefabricated according to its function and, for example, manufactured as standard parts for other uses. They are then customized for the aircraft's refueling connection by welding on the wing flanges. The wing flanges can be individually positioned, designed, and attached to the aircraft structure, depending on the shape and orientation of the mounting flanges.

[0013] It is further proposed that the wing flanges be attached to the mounting flanges via a radially compliant connection. This compliant connection allows for radial expansion or contraction of the pipe section or coupling, for example due to temperature changes, without the pipe section or coupling losing its fixation to the aircraft structure.

[0014] It is further proposed that friction-reducing washers be provided between the blade flanges and the mounting flanges. These friction-reducing washers allow for greater compressive forces, i.e., holding forces, between the blade flanges and the mounting flanges without restricting radial movement. Such friction-reducing washers could, for example, be made of Teflon. If the fastening is achieved using through bolts that pass through corresponding mounting openings in the mounting flanges and the blade flanges, the washers are preferably designed as flat washers. These flat washers then have a corresponding opening through which the through bolts extend.

[0015] The invention is explained below using a preferred embodiment with reference to the accompanying figures. This shows

[0016] Fig. 1 shows a cross-section of a section of the hull with a refueling port, and

[0017] Fig. 2A-F shows an oblique view, a rear view and a side view of the refueling connection with various sectional views.

[0018] Figure 1 shows a section of the fuselage 1 of an aircraft. The fuselage 1 is the central, usually tubular, middle section of the aircraft, which is oriented in the direction of flight and serves to accommodate passenger seats, luggage, cargo, the cockpit unit, and / or the aircraft's central technical systems in general, and therefore has a correspondingly large cavity whose shape is adapted to its function. The wings of the aircraft, or in the case of a single-wing aircraft, the wing itself, are attached to the fuselage 1. These wings serve to generate lift for the aircraft and are therefore aerodynamically shaped.

[0019] In the hull 1, a tank (not shown) is provided, which is cylindrical with a circular cross-section for the purpose of energy-optimized cooling with the largest possible volume and serves to hold liquid hydrogen, i.e., a cryogenic fuel, at a temperature of less than minus 253 °C.

[0020] A refueling port is provided on the underside of the fuselage 1. This port is formed by a connection part 3 with a centrally located connection 5 for connecting an LH2 coupling piece that is inserted from the outside. The connection part 3 is attached to the inside of the fuselage 1 in the area of ​​an edge of a cutout 16 in the fuselage 1 by a first edge section 10, e.g., via a weld or rivet connection. Furthermore, a retaining plate 2 is provided, which is also attached to the opposite edge of the cutout 16 on the inside of the fuselage 1 by a first edge section 11, likewise via a weld or rivet connection. The cutout 16 in the fuselage 1 is rectangular, and the connection part 3 and the retaining plate 2 are attached to two opposite edges of the cutout 16.

[0021] The connecting part 3 and the retaining plate 2 are connected to each other at an angle C of 90 degrees, i.e., at right angles, via their second edge sections 12 and 13, which are arranged at opposite ends of the connecting part 3 and the retaining plate 2 with respect to the first edge sections 10 and 11. The connecting part 3 is attached to the edge of the cutout 16 with its first edge section 10 such that the connecting part 3 is aligned at an angle A to an imaginary extension of the fuselage 1 in the cutout. The retaining plate 2 is attached to the edge of the cutout 16 with its first edge section 11 such that

[0022] The retaining plate 2 is attached to the cutout 16 such that it is aligned at an angle B to an imaginary extension of the fuselage 1 within the cutout. The angle A between the connecting part 3 and the imaginary extension of the fuselage 1 within the cutout 13 is greater than the opposite angle B between the retaining plate 2 and the imaginary extension of the fuselage 1 within the cutout. Furthermore, the retaining plate 2 has a greater length from the first edge section 11 to the second edge section than the connecting part 3 has from the first edge section 10 to the second edge section 12.

[0023] This geometry results in a insertion direction for the coupling piece at connection 5 in the X-direction, in this case orthogonal to the plate-shaped connection part 3, which is arranged at an angle D between 0 degrees and 90 degrees to a horizontal plane H of the aircraft when the aircraft is on the ground. This allows the coupling piece of the LH2 coupling to be inserted obliquely from above into the refueling port located on the underside of the fuselage 1, thus reducing the probability of embrittlement of the O-rings in the LH2 coupling piece and the associated probability of failure.

[0024] Figure 2A shows the same refueling port on fuselage 1 from the view inside the aircraft.

[0025] The connecting part 3 is additionally stiffened by two stiffening ribs 8 and 9, which also form a stiffened connection to the retaining plate 2.

[0026] The connection 5 of the connection part 3 is itself designed as a coupling 23 for a counterpart of an LH2 coupling, wherein a pipe section 7 of a tube is attached to the coupling 23, which is in a fluid-conducting connection with the tank. The coupling 23 is specifically designed as a refueling connection for a coupling piece of an LH2 coupling for cryogenically cooled liquid hydrogen. If refueling with a different cryogenic propellant is intended, the coupling 23 can also be specially designed for this purpose. Furthermore, other service connections for power supply, water drainage and / or water supply, and the like, can also be provided on the connection part 3.

[0027] The refueling port is located in the lower half of the fuselage.

[0028] 1 is arranged, whereby the provided connecting part 3 and the orientation of the connection 5 thereon still allow the coupling piece to be inserted for refueling from above. The orientation of the coupling piece's feed direction can be individually configured by the orientation of the connecting part 3, whereby the feed direction is decoupled from the orientation of the fuselage 1 and the local fuselage shape and depends only on the orientation of the connection 5 and the connecting part 3. This solution enables the aircraft to be refueled in a direction optimized for service and handling.

[0029] Furthermore, the right-angled connection of the mounting plate

[0030] The angle C between the second edge sections 12 and 13 of the connecting part 3 and the retaining plate 2 does not restrict the operating range for supplying the coupling piece and contacting the coupling piece with the connection 5, and the enlargement of the cutout 16 of the body 1 can be limited to a minimum. An angle C greater than 90 degrees would not increase the operating range but would only increase the cutout 16 in the body 1, whereas an angle C less than 90 degrees would reduce the cutout 16 but also the operating range for accessing the coupling piece. Therefore, the proposed angle C of 90 degrees at the junction of the second edge sections 12 and 13 of the connecting part 3 and the retaining plate 2 is the optimum with regard to fulfilling the criteria.

[0031] Figures 2A to 2F show an enlarged view of a section of the connection part 3 with the stiffening ribs 8 and 9 from the inside of the fuselage 1, in various perspectives and sectional views. The connection 5 is formed here by the coupling 23, which forms one coupling half for inserting a second coupling half of an LH2 coupling. From the inside of the fuselage 1, a pipe section 7 is attached to the coupling 23, which is in a fluid-flow connection with a tank (not shown) located in the fuselage 1.

[0032] To attach the pipe section 7 to the connecting part 3, the latter is provided with two radially projecting wing flanges 17 and 20, which are attached to the pipe section 7, for example, by a separate fastening process such as welding. Instead of welding, the wing flanges 17 and 20 can also be attached to the pipe section 7 by another fastening method, such as gluing or as part of a ring clamp using a clamping connection. By attaching the pipe section 7 to the connecting part 3, the coupling 23 is also indirectly attached to the connecting part 3, either inserted into the pipe section 7 or separately attached to it. It is also conceivable to arrange the wing flanges 17 and 20 accordingly on the coupling 23 and then attach the coupling 23 to the connecting part 3, which would then serve to fasten the pipe section 7.In this case, the pipe section 7 would be indirectly attached to the aircraft via the coupling 23.

[0033] The connecting part 3 is provided with two L-shaped retaining flanges 18 and 21, which are fixed to the connecting part 3, for example, by a spot weld, via a base section 14. The L-shaped retaining sections 18 and 21 each also have a support arm 15 projecting perpendicularly from the base section 14.

[0034] The retaining flanges 18 and 21 are shaped and attached to the connecting part 3 such that the support arms 15 of the retaining sections 18 and 21 are spaced apart and extend axially to such an extent that the pipe section 7 with the wing flanges 18 and 21 overlaps the support arms 15 of the retaining flanges 28 and 21 in the secured position. The retaining flanges 18 and 21 have circular mounting openings 22 in the support arms 15. The wing flanges 17 and 20 have elongated mounting openings 19, which are shaped and arranged such that their longer principal axes are directed radially outwards. Furthermore, the elongated mounting openings 19 are arranged such that, in the secured position of the pipe section 7, they overlap the circular mounting openings 19 of the retaining flanges 18 and 21.

[0035] The retaining flanges 18 and 21 are attached to the connecting part 3 such that the base sections of the retaining flanges 18 and 21 are oriented in opposite directions, in the present embodiment upwards and downwards. Furthermore, the retaining flanges 18 and 21 are positioned on the connecting part 3 such that the upper surface of the support arm 15 of the retaining flange 18 on the right in the illustration and the lower surface of the support arm 15 of the retaining flange 21 on the left in the illustration each form a stop surface for the wing flanges 17 and 20. The pipe section 7 is fastened by first placing the pipe section 7 in a rotational position in which the wing flanges 17 and 20 do not rest against the retaining flanges 18 and 21 and the wing flanges 17 and 20 are arranged rotated at an angle of less than 180 degrees counterclockwise to the respective retaining flanges 18 and 21.In a second step, the pipe section 7 is then rotated clockwise until, as described above, it comes into contact with the support arms 15 of the retaining flanges 18 and 21 in an aligned arrangement of the mounting openings 19 and 22, with the wing flanges 17 and 20 aligned. The pipe section 7 is then finally secured by inserting appropriate mounting screws into the mounting openings 19 and 22 and tightening corresponding nuts onto the ends of the mounting screws. Friction-reducing washers, e.g., made of Teflon or with a Teflon coating, e.g., in the form of washers, can also be provided between the clamping surfaces of the wing flanges 17 and 20, the retaining flanges 18 and 21, and the mounting screws.

[0036] The proposed fastening of the pipe section 7 with the radially projecting wing flanges 17, 20 to the retaining flanges 18, 21 allows the pipe section 7 itself to expand or contract radially, at least slightly, without mechanically damaging the fastening. The pipe section 7 thus remains securely fastened even during thermal expansion and contraction. For this purpose, the thickness and material of the wing flanges 17, 20 can be deliberately designed to allow for slight elastic deformation under the applied forces without undergoing plastic deformation themselves.

[0037] Furthermore, the elongated mounting holes 19 provided in the wing flanges 17, 20 allow for radial play in the mounting, thereby compensating for radial expansion and contraction of the pipe section 7 by movement of the wing flanges 17, 20 relative to the retaining flanges 18, 21. This intentionally created radial movement is further enhanced by the use of friction-reducing intermediate washers, which enable the application of correspondingly higher clamping forces without impairing the radial movement. The wing flanges 17, 20 and the retaining flanges 18, 21 preferably abut each other with corresponding clamping surfaces that lie in a planar plane or complement each other to form a planar plane.The wing flanges 17,20 are arranged diametrically on the tube section 7, so that the tube section 7 is attached symmetrically to its central axis S to the connecting part 3 of the aircraft structure.

[0038] The fastening of the pipe section 7 via the wing flanges 17, 20 is designed such that symmetrical clamping forces result with respect to a central axis S of the pipe section 7, and particularly preferably point-symmetrical clamping forces result with respect to the center point P of the pipe section 7. The invention has been described with respect to fastening the refueling connection via the pipe section 7. However, the fastening can also be effected with the same advantages via wing flanges 17, 20 arranged on the coupling 23. 1 Fuselage

[0039] 2 Mounting plate

[0040] 3 Connection part

[0041] 4 cavities

[0042] 5 connection

[0043] 6 clamping element

[0044] 7 pipe sections

[0045] 8 stiffening rib

[0046] 9 stiffening rib

[0047] 10 First marginal section

[0048] 11 First marginal section

[0049] 12 Second marginal section

[0050] 13 Second marginal section

[0051] 14 Basic section

[0052] 15 support arm

[0053] 16 Excerpt

[0054] 17 wing flange

[0055] 18 retaining flange

[0056] 19 Mounting opening

[0057] 20 wing flange

[0058] 21 retaining flange

[0059] 22 Mounting opening

[0060] 23 Clutch

[0061] Angles A, B, C, D

[0062] H Horizontal plane

[0063] X Connection direction

[0064] S center axis

[0065] P Center

Claims

Claims:

1. Aircraft with a refueling port which is in a fluid-technical connection with a tank arranged in the aircraft, wherein -the refueling port and the tank are equipped to receive a cryogenic fuel, wherein -the refueling port comprises a pipe section (7) specially designed for conveying a cryogenic fuel and a coupling (23) which is fixed to an aircraft-mounted structure, characterized in that -the pipe section (7) and / or the coupling (23) has at least two diametrically arranged radially outwardly projecting wing flanges (17, 20), and -at least two protruding retaining flanges (18,21) are provided on the aircraft-mounted structure, on which the pipe section (7) and / or the coupling (23) is attached to the wing flanges (17,20) in an aircraft-mounted manner.

2. Aircraft with a refueling port according to claim 1, characterized in that -the wing flanges (17,20) are attached to the retaining flanges (18,21) with the same sides in relation to the circumferential direction of the pipe section (7) and / or the coupling (23).

3. Aircraft according to one of claims 1 or 2, characterized in that -the wing flanges (17,20) are arranged in pairs with each of their sides in a common planar plane.

4. Aircraft according to one of claims 1 to 3, characterized in that -Wing flanges (17,20) are welded to the pipe section (7) and / or the coupling (23).

5. Aircraft according to one of claims 1 to 4, characterized in that -the wing flanges (17,20) are attached to the retaining flanges (18,21) via a radially loose connection.

6. Aircraft according to claim 5, characterized in that friction-reducing intermediate disks are provided between the wing flanges (17,20) and the retaining flanges (18,21).

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