Apparatus

Abstract

A conduit for transporting cryogenic material and electrical current comprises: a first conduit portion 110 for a cryogenic material; and a second conduit portion 120 to house a vacuum, the first port

Description

Technical Field The present invention is concerned with electrical conduits. Specifically, the present invention is concerned with connections in electrical conduits. The present invention may be advantageously used where both electrical current and cooling fluids are to be transported. The present invention may be advantageously used inside electrically powered aircraft. Modern systems in aircraft provide electrical conduits that may have joints that are assembled via o-rings, nuts and bolts or the like. These systems are widely prevalent and are suitable for the requirements of most modern aircraft. There are aims for electrically powered aircraft to be commercially available in the near future. There are arrangements of such aircraft that provide improved emissions profile alongside being more sustainable than typical fuel powered aircraft. There are improvements that can be made in the field of electrical conduits for electrically powered aircraft, whether partially or fully electrically powered aircraft. The presently disclosed system may be highly advantageous in aerospace applications however may also be used in any electrical energy transmission systems, such as in any vehicles, any machinery or the like. Summary of the Invention Aspects of the invention are set out in the accompanying claims. In accordance with some embodiments described herein, there is provided a conduit for transporting at least one of cryogenic material and electrical current, the conduit comprising: a first conduit portion arranged to carry a cryogenic material; and, a second conduit portion arranged to house a vacuum, the first conduit portion arranged at least partially within the second conduit portion; wherein the first conduit portion has a first end portion and a second end portion each comprising a bi-metallic joint, wherein each bi-metallic joint has a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material, wherein the second joint portion is larger than the first joint portion, wherein the second conduit portion has a first end portion and a second end portion each comprising a bimetallic joint, wherein each bi-metallic joint has a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material, wherein the second joint portion is larger than the first joint portion. The present conduit provides a highly reliable and easily constructed conduit for cryogenic material and electrical current. The conduit provides high levels of thermal insulation for the cryogenic material and therefore improves the overall efficiency of the cryogenic system by reduce the impact of incoming thermal radiation. The conduits may be part of a closed cryogenic material circuit or the like. Such a closed system may benefit from an arrangement in which cryogenic material is maintained at a low temperature to reduce the requirement of recooling the material during use. Welding is a common approach in the field. Welding however can be negatively impacted by cryogenic materials weakening the weld lines and reducing the overall robustness of the conduit. The present disclosure may use welding in a manner that reduces the negative impact of welding when used in low temperature environments. The present system may use super insulated vacuum lines (SIVLs). In examples, the second joint portion of each bi-metallic joint is arranged at an end of the conduit portion. This arrangement improves the ease with which the joint portions can be connected to one another and therefore increases the ease of manufacturing of the conduits. In turn, this reduces the cost and energy required to manufacturing the conduits. In examples, each first joint portion comprises aluminium and wherein each second joint portion comprises steel. The inventors have found that such materials provide improved ease of manufacturing and assembly. Aluminium is particular advantageous in aerospace applications due to being lightweight. Aluminium is not often used in modern joints as it is not easily welded. As such, the present arrangement overcomes a weakness of aluminium in order to use it in the present arrangement. In examples, the conduit further comprises a sleeve portion, wherein the second conduit portion is arranged at least partially within the sleeve portion, wherein the sleeve portion is arranged to move along the second conduit portion. The sleeve portion is arranged to move along the second conduit portion to provide a moveable element to provide a connection between conduits at a suitable position. Providing manoeuvrability of the sleeve portion provides a greater array of locations where the connection can be. This sleeve portion may instead be used to provide a connection between the conduit and a further conduit (so not merely between the first conduit portion and the second conduit portion). It is envisaged that the conduit may be connected to a further conduit to provide a conduit network. This sleeve portion may provide a reliable and robust connection that maintains a vacuum and therefore maintains the high resistance to incoming thermal energy. In examples, the first conduit portion further comprises spacers arranged on an outer surface of the first conduit portion arranged to connect to an inner surface of the second conduit portion. Spacers are highly advantageous in providing stability of the inner first conduit portion within the outer second conduit portion. This improves the ease of arranging the first conduit securely within the second conduit and therefore improves the ease of manufacturing and reliability of the overall conduit construction. Spacers can be made to provide a limited amount of contact between the two portions so as to reduce thermal transfer between the conduit portions. The spacers may be thin and / or frame like to provide a limited amount of contact along which thermal energy may be passed. In examples, the conduit further comprises an electrical conductor for conducting an electrical current, the electrical conductor arranged within the first conduit portion. The arrangement is designed to be able to carry cryogen and electrical current. Arranging an electrical conductor within the first conduit portion, which is arranged to carry a cryogenic material, the electrical conductor can be maintained at a lower temperature and therefore provide high electrical efficiencies. Furthermore, the electrical conductor is protected by virtue of being located within the first conduit portion which is itself located at least partially within the second conduit portion. In accordance with some embodiments described herein, there is provided a method of forming a conduit, the method comprising: forming bimetallic joints via comprising connecting a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material; connecting bimetallic joints to ends of a first conduit portion arranged to carry a cryogenic material; connecting bimetallic joints to ends of a second conduit portion arranged to house a vacuum; and, arranging the first conduit portion at least partially within the second conduit portion. The method herein provides a reliable and robust method for providing a conduit that is suitable for carrying cryogenic material and / or electrical current. The bimetallic joints have been found to be reproducible to a high tolerance and are arranged to enable a first conduit to be easily and reliably connected to a second conduit. The conduits in themselves are strongly resistant to incident thermal energy which enables cryogenic material to be maintained at low temperatures which in turn allows electrical conductors to be maintained in highly electrically efficient temperature regimes. In examples, the method further comprises providing a sleeve portion, wherein the second conduit portion is arranged at least partially within the sleeve portion, wherein the sleeve portion is arranged to move along the second conduit portion. In examples, the method further comprises connecting a first conduit section to a second conduit section, each conduit section comprising a respective first conduit portion and a respective second conduit portion. The method can be used to form a combined conduit of any length. This may be particularly advantageous where the individual conduits may be constructed of smaller more manageable dimensions and then a larger conduit constructed from those smaller length conduits. This is useful when constructing conduit arrangements of varying shape and sizes for inclusion in specific locations or the like which may be within vehicles or the like. In examples, connecting a first conduit section to a second conduit section comprises: aligning the first conduit section and the second conduit section; moving the sleeve portion over a connection between the first conduit section and the second conduit section; and, connecting the sleeve portion to both the first conduit section and the second conduit section. Use of the sleeve portion to align and connect the first section to a second section improves the reliability and robustness of the conduit and the construction method for the conduit. In particular, this ensures that alignment of the outer portions of the conduits is very reliable which is important for improving the alignment of the inner portions of the conduits. In examples, connecting the sleeve portion to both the first conduit section and the second conduit section comprises: connecting a first portion of the sleeve portion to an end portion of the first conduit section and connecting a second portion of the sleeve portion to an end portion of the second conduit section. This further improves alignment between the conduit sections. This improves the reliability and robustness of the manufacturing method for the conduits. In turn this improves the conduit that is manufacturer by the method. In examples, connecting a first conduit section to a second conduit section comprises: providing a resilient element between the first conduit section and the second conduit section; connecting a first end of the resilient element to the first conduit section; and, connecting a second end of the resilient element to the second conduit section. The resilient element may be used to provide a bias within the system to bring the first conduit section and the second conduit section together. The resilient element may be used to account for expansion and contraction of the conduits during use and transport of cryogenic material. This may improve the connection between the conduits during the full lifetime of the conduits. In examples, the method further comprises drawing at least one electrical conductor through the conduit. Drawing an electrical conductor through the conduit is a reliable and safe method by which the electrical conductor can be introduced into a pre-formed conduit. Drawing is a method of pulling the wire into position using for example a wire or the like. This can ensure that the In examples, connecting a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material comprises: connecting the first joint portion and the second joint portion via at least one of: friction welding; explosive bonding; resistance welding; ultrasonic welding; and, friction and resistance welding, and, wherein connecting bimetallic joints to ends of a first conduit portion and a second conduit portion comprises: connecting bimetallic joints via gas tungsten arc welding to ends of a first conduit portion and a second conduit portion. Gas tungsten arc welding (GTAW) may also be referred to as Tungsten Inert Gas (TIG) welding. The combination of welding in these examples are reliable and allow for a strong robust joint to be formed that may withstand the cold temperatures of the cryogenic material. In examples, connecting the first conduit section to the second conduit section comprises connecting the first conduit section to the second conduit section via orbital welding. Orbital welding is well suited to work on the conduits as this is a highly stable approach for welding and this provides a robust and reliable weld for the conduit discussed herein. In examples, connecting the sleeve portion to both the first conduit section and the second conduit section comprises connecting the sleeve portion to both the first conduit section and the second conduit section via at least one of orbital welding and gas tungsten arc welding. This method provides a highly stable approach for welding and this provides a robust and reliable weld for the conduit discussed herein. In accordance with some embodiments described herein, there is provided a modular conduit network for transporting cryogenic material and electrical energy; the network comprising: a plurality of conduit sections each conduit section comprising a cryogenic conduit arranged at least partially within a vacuum tube; a first joining sleeve arranged over a first end of a first conduit section and a first end of a second conduit section, the first joining sleeve connected to the first conduit section and the second conduit section, a second joining sleeve arranged over a second end of the second conduit section and over a first end of a third conduit section, the second joining sleeve connected to the second conduit section and the third conduit section, wherein the first joining sleeve and second joining sleeve are disconnectedly connected to the respective conduit sections, wherein the second conduit section is arranged to be removable from the conduit network when the first joining sleeve and second joining sleeve are disconnected from the respective conduit sections. The conduit disclosed herein may be combined with similar conduits to form a modular network of conduits. The network is modular as the conduits may be introduced following the steps above. The conduits may be removed by breaking or disconnecting a connection between the conduits and remove one or more conduits. This may be highly beneficial during repair or maintenance of the conduits. For example, if a break occurs in a conduit and a leak occurs from that conduit portion, said conduit portion may be removed and replaced while the remainder of the network is re-used. This increases the overall lifetime of the network while also reducing the cost of repair and maintenance. In accordance with some embodiments described herein, there is provided an aircraft comprising the conduit any of the above embodiments or examples or the modular conduit network of any of the above embodiments or examples. The present system allows for highly effective transport of cryogenic material and electrical current. This renders the present system highly advantageous for use in aircraft. In examples, the aircraft is at least partially electrically powered. The present system allows for highly effective transport of cryogenic material and electrical current. The present conduit and / or modular conduit network is therefore highly effective in transporting electrical current which is advantageous in an at least partially electrically powered aircraft. Furthermore, electrically powered aircraft may use cryogenic material which the present conduit may also transport. As such, there are clear synergies between use in an at least electrical powered aircraft and the conduit disclosed herein. In examples, the aircraft further comprises: a cryogenic material store for storing cryogenic material; and a fuel cell for provision of electrical power for use in the aircraft. In examples, the conduit or conduit network is arranged to transport cryogenic material from 5 the cryogenic material store to the fuel cell. The conduits in the present disclosure are highly suited to transporting cryogenic material and therefore use in such a wider system is advantageous. 10 In examples, the conduit or conduit network is arranged to conduct electrical power from the fuel cell. Brief Description of the Drawings One or more embodiments of the invention will now be described, by way of example only, and with reference to the following figures in which: Figure 1 shows a schematic view of a conduit for transporting at least one of cryogenic material and electrical current according to an example of the present disclosure; Figure 2 shows a schematic view of a portion of a conduit according to an example of the present disclosure; Figure 3 shows a schematic view of a conduit according to an example of the present disclosure; Figure 4 shows a schematic view of a first conduit portion of a conduit according to an example of the present disclosure; Figure 5 shows a schematic view of a conduit arrangement according to an example of the present disclosure; and, Figure 6A shows a schematic view of a conduit network according to an example of the present disclosure; and, Figure 6B shows a schematic view of a partial conduit network according to an example of the present disclosure. Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”. The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples. It will also be recognised that the invention covers not only individual embodiments but also combination of the embodiments described herein. The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc, other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future. Detailed Description The present method and system provides a highly robust and reliable system for transporting at least one of cryogen and electrical current. Specifically, the present method and system provides leakage prevention of the scale of around IxlO 9 mbar litre / second, while remaining installable and maintainable on electrically powered aircraft without causing potential damage. The present system may be used in an aircraft that is electrically powered (either partially or fully). This electrical power generation may occur in a number of ways. Electrical power can be efficiently conducted along conductors when electrical conduits are maintained in low temperature conditions. The present invention looks to provide electrical conduits that provide high electrical conductivity to improve the electrical efficiency of the arrangement in which the conduits are installed. The present invention provides a robust and reliable arrangement that may be effective at transporting both cryogen and electrical current. Indeed, the present disclosure teaches a method that is more reliable than previous methods for creation of such a conduit. The present invention may use a cryogenic or very low temperature fluid medium to cool electrical conductors along which high power electrical energy may be conducted. The present invention may be used in both a cryogenic material supply conduit and a cryogenic propulsion feeder conduit. The electrical conductors discussed herein may be maintained at hyperconducting condition by a cryogenic material. This material may be arranged to flow along a conduit to provide cooling to electrical conductors. This material may be in fluid form. The material may be in a closed loop system. An invention described herein relates to thermal management systems and electrical networks for aircraft. A particular use for this invention may be in an aircraft that is in some way electrically powered. This may be an aircraft with an electrically drivable motor or a drivable motor that is at least partially electrically driven. Aircraft propulsion systems generate heat and can be more efficient if that heat can be removed from the system. As such, the present thermal management system provides improved control over the thermal energy generated in the aircraft and therefore can provide great efficiencies for the aircraft and aircraft systems and components, such as electrical propulsion elements. Indeed, electrical efficiency can be improved by careful use of low temperatures. This can be provided herein in a conduit that can provide reliable transportation in a conduit of cryogenic material and electrical current. Referring now to Figure 1, there is shown a schematic view of a conduit 100 for transporting at least one of cryogenic material and electrical current according to an example of the present disclosure. The conduit 100 has a first conduit portion 110 arranged to carry a cryogenic material and a second conduit portion 120 arranged to house a vacuum. The first conduit portion 110 is arranged at least partially within the second conduit portion 120. In the example shown in Figure 1, a large proportion of the first conduit 110 is arranged within the second conduit portion 120. In the example shown in Figure 1, the first conduit portion 110 has a first end portion 114 and a second end portion 116 each comprising a bi-metallic joint 130, 140. Each bi-metallic joint 130, 140 has a first joint portion 132, 142 formed of a first metallic material and a second joint portion 134, 144 formed of a second metallic material, wherein the second joint portion 134, 144 is larger than the first joint portion 132, 142. In the example shown in Figure 1, the second conduit portion 120 has a first end portion 124 and a second end portion 126 each comprising a bi-metallic joint 150, 160. Each bi-metallic joint 150, 160 has a first joint portion 152, 162 formed of a first metallic material and a second joint portion 154, 164 formed of a second metallic material, wherein the second joint portion 154, 164 is larger than the first joint portion 152, 162. The first conduit portion 110 is arranged to carry a cryogenic material and this material may be located in portion 112 indicated in Figure 1. The second conduit portion 120 is arranged to house a vacuum and this vacuum may be located in portion 122 indicated in Figure 1. The vacuum 122 improves the maintenance of a low temperature at conduit portion 110 which is arranged to hold a cryogenic material. The vacuum therefore improves the overall reliability of the system and reduces the requirement on re-cooling cryogenic material. The advantage of the present conduit 100 is that it may be combined with other similar or identical conduits to form a conduit network. The combining can occur in a number of ways. The combining does not require welding. This is highly advantageous as welds lose strength in low temperature arrangements and can become brittle and break. Furthermore, it can be difficult to disassemble a weld to replace a portion of the conduit network, this is made far more straightforward with the conduit and joining method disclosed herein. The present system may provide leak tight joints that are both strong and durable. In the example of Figure 1, the second joint portion 134, 144, 154, 164 of each bi-metallic joint 130, 140, 150, 160 is arranged at an end of the conduit portion 110, 120. The conduit portions 110, 120 have two ends in the arrangement of Figure 1. The joint sections are arranged at the end of the conduits and are well located for connecting to subsequent conduits in a network of conduits. The arrangement of Figure 1 shows the larger joint portion located externally (further away from a centre point of the conduit) of a smaller joint portion. This leads to an easier arrangement of connection for the conduit to a subsequent conduit. In examples, each first joint portion comprises aluminium and each second joint portion comprises steel. Aluminium is desirable for use in aerospace applications as it is lightweight and sturdy. Welding aluminium can be very troublesome (the oxidation layer on Al can increase the difficulty of manufacture of a joint from Al) and therefore the joint herein is formed of an aluminium and stainless steel material. Referring now to Figure 2, there is shown a schematic view of a portion 200 of a conduit according to an example of the present disclosure. The portion 200 does not include a first conduit portion (as shown in Figure 1) rather the portion 200 of Figure 2 shows the second conduit portion 220. There may be a first conduit located entirely or partially inside the second conduit portion 220, however for simplicity this is not shown in the examiner of Figure 2. The example in Figure 2 has many of the same features (or similar features) as Figure 1, the reference numerals of which are increased by 100 in Figure 2. For example second conduit portion 220 of Figure 2 has a similar or the same function as second conduit portion 120 of Figure 1. All these features may not be discussed in detail herein. Such features include a portion 222 for housing a vacuum, a first end portion 224 and a second end portion 226 each with a bi-metallic joint 250, 260. The joints 250, 260 have a first joint portion 252, 262 and a second joint portion 254, 264. The portion 200 of a conduit shown in Figure 2 also has a sleeve portion 270 arranged externally to the second conduit portion 220. The sleeve portion 270 may be wrapped around the second conduit portion 220. The sleeve portion 270 is shown abutting the outer surface of the second conduit portion 220 in the example of Figure 2. The sleeve portion 270 need not abut an outer surface of the second conduit portion 220. The sleeve portion 270 is arranged to move. The sleeve portion 270 may be arranged to broadly move along the second conduit portion 220. In the example shown in Figure 2, the sleeve portion 270 is arranged to move along a direction indicated by double-ended arrow A. The sleeve portion 270 may be arranged to slide along an outside of the second conduit portion 220. The sleeve portion 270 may be used in forming a connection to a subsequent conduit in the formation of a conduit network. In this way, the sleeve portion 270 provides a robust and reliable method to connect one conduit to another conduit. In examples, the sleeve portion 270 may be arranged to slide along a bi-metallic joint of the second conduit portion 220. In this way, the sleeve portion 270 may cover, e.g., the second joint portion 264 of one bi-metallic joints 260 of the second conduit portion 220. The sleeve portion 270 may be sized to cover a further second joint portion of a further bi-metallic joint 260 of a further conduit portion. The conduits may be connected to one another by virtue of the sliding sleeve portion 270. The sleeve portion may assist in maintaining a vacuum in the conduits while also allowing a reliable connection between conduits in a network. Referring now to Figure 3, there is shown a schematic view of a conduit 300 according to an example of the present disclosure. The conduit 300 includes a first conduit portion 310 and a second conduit portion 320. The example in Figure 3 has many of the same features (or similar features) as Figures 1 and 2. The reference numerals of Figure 3 for similar elements are increased by 200 from those elements in Figure 1. For example second conduit portion 320 of Figure 3 has a similar or the same function as second conduit portion 120 of Figure 1. All such features may not be discussed in detail herein. Similar or identical features include first conduit portions 110,310, second conduit portions 120, 320 etc. The example shown in Figure 3 also includes at least one spacer 380 arranged to provide a connection between the first conduit portion 310 and the second conduit portion 320. A spacer 380 may be an element that is arranged to provide some structural rigidity for the first conduit portion 310 while within the second conduit portion 320. The conduit of any of the present examples may use one or more spacers to arrange the first conduit 310 securely within the second conduit 320. The spacer 380 is advantageously minimal in structure to provide a limited thermal conduction path from the second conduit portion 320 to the first conduit portion 310. The spacer may be frame-like or be thin or the like to reduce the path along which thermal energy can be conducted to the first portion 310. The first conduit portion 310 is preferably ata very low temperature and therefore thermal isolation, to as great an extent as possible, from the second conduit portion 320 is advantageous. Spacers 380 are advantageous for providing effective stability within the structure. This stable positioning is provided with minimal increase in thermal energy transfer from second conduit portion 320 to first 310. The system may have a series of spacers 380 to improve ease of locating the first conduit portion 310 securely within the second conduit portion 320. Referring now to Figure 4, there is shown a schematic view of a first conduit portion 410 of a conduit according to an example of the present disclosure. The example in Figure 4 has many of the same features (or similar features) as Figures 1, 2 and 3. The reference numerals of Figure 4 for similar elements are increased by 300 from those elements in Figure 1. For example first conduit portion 410 of Figure 4 has a similar or the same function as first conduit portion 110 of Figure 1. All such features may not be discussed in detail herein. Similar or identical features include first conduit portions 110, 410, and first bimetallic joint 130, 430 etc. The example shown in Figure 4 shows a first conduit portion 410 with an electrical conductor 490 for conducting an electrical current arranged within the first conduit portion 410. The electrical conductor 490 can be part of an electrical network for providing electrical signals through a network. The electrical conductor 490 may be part of a power or propulsion arrangement for a vehicle. The electrical conductor 490 may be maintained in a low temperature environment to increase the electrical efficiency of the conductor. The first conduit portion 410 may contain a cryogenic material which is provided through a conduit network. The cryogenic material may be used in e.g. propulsion arrangements. The cryogenic material may be used in fuel cells or the like or may be part of a closed loop system. The cryogenic material maintains the electrical conductor 490 in a low temperature state. The second conduit portion (now shown in the example of Figure 4) is arranged around at least some portion of the first conduit portion 410 and is suitable for holding the first conduit in a vacuum to reduce thermal energy reaching the first conduit portion 410. In the example of Figure 4, this is particularly advantageous for maintaining the cryogenic material at a low temperature as well as maintaining the electrical conductor 490 at a low temperature. The electrical conductor may conduct AC or DC current. Referring now to Figure 5, there is shown a schematic view of a conduit arrangement 500 according to an example of the present disclosure. The conduit arrangement 500 contains two conduits 505, 505’. Both conduits 505, 505’ may be according to any of the examples shown in earlier Figures or discussed herein. The conduits 505, 505’ both have joints with larger, more externally located portions 554, 564’. The example in Figure 5 has many of the same features (or similar features) as Figures 1, 2, 3 and 4. The reference numerals of Figure 5 for similar elements are increased by 400 from those elements in Figure 1. For example second joint portions 154, 164 of Figure 4 have a similar or the same function as second joint portions 554, 564 of Figure 1. All such features may not be discussed in detail herein. Figure 5 shows a pair of conduits 505, 505’ whereby similar features are shown with the same numbers with a prime (‘) for conduit 505’. In the arrangement of Figure 5, a sleeve portion 570 is arranged to move along the direction indicated by double-ended arrow A. The sleeve portion 570 is arranged such that the sleeve portion 570 may be moved over both the second joint portions 554, 564’ which are facing each other in the arrangement of Figure 5. The sleeve portion 570 may be used to secure the relative positions of the two conduits 505, 505’ prior to connecting the conduits 505, 505’ to one another. Once the sleeve portion 570 is moved into position, the sleeve portion 570 may be connected to the bimetallic joints 550, 560’. The sleeve portion 570 may be connected to the steel portions 554, 564’ of the bimetallic joints 550, 560’. In examples, the sleeve portion 570 maybe welded to the bimetallic joints 550, 560’. In examples, the sleeve portion 570 maybe welded to the steel portions 554, 564’ of the bimetallic joints 550, 560’. In examples, the welding process may comprise orbital welding. The process of forming a conduit and then a conduit network may involve a series of steps that ensure high reproducibility and that therefore produce a highly reliable series of conduits. A method of forming a conduit may involve forming bimetallic joints via comprising connecting a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material; connecting bimetallic joints to ends of a first conduit portion arranged to carry a cryogenic material; connecting bimetallic joints to ends of a second conduit portion arranged to house a vacuum; and, arranging the first conduit portion at least partially within the second conduit portion. In forming a conduit network, a first conduit and a second may be aligned and then connected. This process may be enhanced using a sleeve portion as noted above. The conduits may be aligned by aligning first conduit portions and then connecting these portions together. This connection may occur via welding. Specifically, this may occur via orbital welding. A sleeve portion may then be used to connect second conduit portions as noted above for a robust arrangement. Specifically, the sleeve portion may be moved over the larger end portions of the bimetallic joints and point welded (e.g. via TIG welding) to secure the second conduit portions to one another. The first conduit portions are arranged at least partially within the respective second conduit portions. The first conduit portions may transport cryogenic material. The second conduit portions may house a vacuum. A cable may be drawn through a conduit using a draw wire or the like to pull the cable into place. The cable may be pulled through the inner conduit (the first conduit portion) which may contain e.g. cryogenic helium in use. A modular conduit network may be provided by connecting a series of conduits as disclosed herein. Such a network is shown in Figure 6A. The network 600 shown in Figure 6A has a series of conduits 605, 605’, 605”, 605”’. Each conduit is connected to a joining conduit, such as conduit 605 is connected to conduit 605’ via sleeve portion 670. The sleeve portion 670 is connected as described above. In this way a network can be formed that is able to transport cryogenic material and electrical signals a reasonably long distance without experiencing significant losses. This is particularly advantageous for use in large vehicles or the like where fuel or electrical current may need to be transported over reasonable distances. In the instance that one of the conduits experiences an issue and requires maintenance or replacement, the present network is highly compatible with rapid maintenance and repair with minimal impact on the remaining elements in the network. Figure 6B shows an example of a conduit network 600 undergoing repair. In an example, one of the conduits is faulty and requires maintenance. In the specific example shown, conduit 605’ experiences an issue. The sleeve portions 670 and 670’ may be disconnected and moved away (as per sleeve portion 670 moving in a direction shown by double-ended arrow A) or disconnected and removed entire (as per portion 670’, not shown in Figure 6B as it has been removed). This allows conduit 605’ to be removed from the network in a direction such as that shown by double-ended arrow B. This allows conduit 605’ to undergo repair, maintenance or replacement while maintaining the remaining elements of the network 600. Such an arrangement reduces the cost of maintenance and increased the speed of repair. In environments such as air travel, this has an immediate impact on the turnaround at airports and therefore allows aircraft to return to being airborne more quickly. This is therefore more economically viable for airlines. Once the conduit is removed, the inner conduit portion may be removed from the outer conduit portion in the event that the first conduit portion is that which requires maintenance. Such removal may also improve the ease of repairing the outer conduit where required. The sleeve portions in the network can be seen to be connected to an end portion of the first conduit and an end portion of the second conduit. For example, sleeve 670 is connected to the right hand end of conduit 605 and the left hand end of conduit 605’. The sleeve portion may be shaped or machined to be lightweight. As such, the sleeve portion is shown in Figures 6A and 6B to be sized just to connect fully to the larger end portions of the bimetallic joints, the sleeve portions could be any size. It may be wasteful and heavier to form larger sleeve portions. As such, sleeves matched to the elements to which the sleeves are to connect are preferable. The present conduits may be expansion loops or bellows within the conduits to compensate for thermal expansion and contraction caused by movement of cryogenic materials within the conduits. Expansion loops may not alter the assembly method above. Introducing bellows may use welding of the bellows to the bi-metallic joints. Such elements may be referred to as resilient elements. The system herein may use any of friction welding; explosive bonding; resistance welding; ultrasonic welding; resistance welding; and gas tungsten arc welding. The present system may use welding however advantageously this welding can be provided at final assembly line. This is advantageous because the system disclosed herein can be installed into the aircraft without significantly impacting the construction of the frame of the vehicle into which the system is installed. In particular, for aerospace applications this is highly advantageous as the airframe of the aircraft need not be altered in manufacture to suit the conduit network disclosed herein. The conduit network disclosed herein may be installed into a vehicle in a similar manner to existing fuel lines of hydraulic systems. The present system uses welding in a manner that is robust and reliable during construction. The present arrangement makes use of orbital welding which, in particular, is a highly reliable welding method.

Claims

1. A conduit for transporting at least one of cryogenic material and electrical current, the conduit comprising:a first conduit portion arranged to carry a cryogenic material; and,a second conduit portion arranged to house a vacuum, the first conduit portion arranged at least partially within the second conduit portion;wherein the first conduit portion has a first end portion and a second end portion each comprising a bi-metallic joint, wherein each bi-metallic joint has a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material, wherein the second joint portion is larger than the first joint portion,wherein the second conduit portion has a first end portion and a second end portion each comprising a bi-metallic joint, wherein each bi-metallic joint has a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material, wherein the second joint portion is larger than the first joint portion.

2. A conduit according to claim 1, wherein the second joint portion of each bi-metallic joint is arranged at an end of the conduit portion.

3. A conduit according to claim 1 or 2, wherein each firstjoint portion comprises aluminium and wherein each second joint portion comprises steel.

4. A conduit according to any preceding claim, further comprising a sleeve portion, wherein the second conduit portion is arranged at least partially within the sleeve portion, wherein the sleeve portion is arranged to move along the second conduit portion.

5. A conduit according to any preceding claim, wherein the first conduit portion further comprises spacers arranged on an outer surface of the first conduit portion arranged to connect to an inner surface of the second conduit portion.

6. A conduit according to any preceding claim, further comprising an electrical conductor for conducting an electrical current, the electrical conductor arranged within the first conduit portion.

7. A method of forming a conduit, the method comprising:forming bimetallic joints via comprising connecting a firstjoint portion formed of a first metallic material and a second joint portion formed of a second metallic material;connecting bimetallic joints to ends of a first conduit portion arranged to carry a cryogenic material;connecting bimetallic joints to ends of a second conduit portion arranged to house a vacuum; and,arranging the first conduit portion at least partially within the second conduit portion.

8. A method according to claim 7, further comprising providing a sleeve portion, wherein the second conduit portion is arranged at least partially within the sleeve portion, wherein the sleeve portion is arranged to move along the second conduit portion.

9. A method according to claim 8, further comprising connecting a first conduit section to a second conduit section, each conduit section comprising a respective first conduit portion and a respective second conduit portion.

10. A method according to claim 9, wherein connecting a first conduit section to a second conduit section comprises:aligning the first conduit section and the second conduit section;moving the sleeve portion over a connection between the first conduit section and the second conduit section; and,connecting the sleeve portion to both the first conduit section and the second conduit section.

11. A method according to claim 10, wherein connecting the sleeve portion to both the first conduit section and the second conduit section comprises:connecting a first portion of the sleeve portion to an end portion of the first conduit section and connecting a second portion of the sleeve portion to an end portion of the second conduit section.

12. A method according to any of claims 9 to 11, wherein connecting a first conduit section to a second conduit section comprises:providing a resilient element between the first conduit section and the second conduit section;connecting a first end of the resilient element to the first conduit section; and, connecting a second end of the resilient element to the second conduit section.

13. A method according to any of claims 7 to 12, further comprising drawing at least one electrical conductor through the conduit.

14. A method according to claim 7,wherein connecting a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material comprises:connecting the first joint portion and the second joint portion via at least one of: friction welding;explosive bonding;resistance welding;ultrasonic welding; and,friction and resistance welding,and, wherein connecting bimetallic joints to ends of a first conduit portion and a second conduit portion comprises:connecting bimetallic joints via gas tungsten arc welding to ends of a first conduit portion and a second conduit portion.

15. A method according to claim 9, wherein connecting the first conduit section to the second conduit section comprises connecting the first conduit section to the second conduit section via orbital welding.

16. A method according to claim 10, wherein connecting the sleeve portion to both the first conduit section and the second conduit section comprises connecting the sleeve portion to both the first conduit section and the second conduit section via at least one of orbital welding and gas tungsten arc welding.

17. A modular conduit network for transporting cryogenic material and electrical energy; the network comprising:a plurality of conduit sections each conduit section comprising a cryogenic conduit arranged at least partially within a vacuum tube;a first joining sleeve arranged over a first end of a first conduit section and a first end of a second conduit section, the first joining sleeve connected to the first conduit section and the second conduit section,a second joining sleeve arranged over a second end of the second conduit section and over a first end of a third conduit section, the second joining sleeve connected to the second conduit section and the third conduit section,wherein the first joining sleeve and second joining sleeve are disconnectedly connected to the respective conduit sections,wherein the second conduit section is arranged to be removable from the conduit network when the first joining sleeve and second joining sleeve are disconnected from the respective conduit sections.5 18. An aircraft comprising the conduit of claims 1 -6 or the modular conduit network of claim17.

19. An aircraft according to claim 18, wherein the aircraft is at least partially electrically powered.1020. An aircraft according to claim 18 or 19, further comprising:a cryogenic material store for storing cryogenic material; anda fuel cell for provision of electrical power for use in the aircraft.15 21. An aircraft according to claim 20, wherein the conduit or conduit network is arranged totransport cryogenic material from the cryogenic material store to the fuel cell.

22. An aircraft according to claim 20 or 21, wherein the conduit or conduit network is arranged to conduct electrical power from the fuel cell.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:-28 02 25C LAI MS1. A conduit for transporting cryogenic material and electrical current, the conduit comprising:5 a first conduit portion arranged to carry a cryogenic material; and,a second conduit portion arranged to house a vacuum, the first conduit portion arranged at least partially within the second conduit portion;wherein the first conduit portion has a first end portion and a second end portion each comprising a bi-metallic joint, wherein each bi-metallic joint has a first joint portion formed of a 10 first metallic material and a second joint portion formed of a second metallic material, wherein the second joint portion is larger than the first joint portion,wherein the second conduit portion has a first end portion and a second end portion each comprising a bi-metallic joint, wherein each bi-metallic joint has a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material, 15 wherein the second joint portion is larger than the first joint portion.

2. A conduit according to claim 1, wherein the second joint portion of each bi-metallic joint is arranged at an end of the conduit portion.20 3. A conduit according to claim 1 or 2, wherein each first joint portion comprises aluminiumand wherein each second joint portion comprises steel.

4. A conduit according to any preceding claim, further comprising a sleeve portion, wherein the second conduit portion is arranged at least partially within the sleeve portion, 25 wherein the sleeve portion is arranged to move along the second conduit portion.

5. A conduit according to any preceding claim, wherein the first conduit portion further comprises spacers arranged on an outer surface of the first conduit portion arranged to connect to an inner surface of the second conduit portion.

306. A conduit according to any preceding claim, further comprising an electrical conductor for conducting an electrical current, the electrical conductor arranged within the first conduit portion.35 7. A method of forming a conduit, the method comprising:forming bimetallic joints comprising connecting a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material;28 02 25connecting bimetallic joints to ends of a first conduit portion arranged to carry a cryogenic material;connecting bimetallic joints to ends of a second conduit portion arranged to house a vacuum; and,5 arranging the first conduit portion at least partially within the second conduit portion.

8. A method according to claim 7, further comprising providing a sleeve portion, wherein the second conduit portion is arranged at least partially within the sleeve portion, wherein the sleeve portion is arranged to move along the second conduit portion.

109. A method according to claim 8, further comprising connecting a first conduit section to a second conduit section, each conduit section comprising a respective first conduit portion and a respective second conduit portion.15 10. A method according to claim 9, wherein connecting a first conduit section to a secondconduit section comprises:aligning the first conduit section and the second conduit section;moving the sleeve portion over a connection between the first conduit section and the second conduit section; and,20 connecting the sleeve portion to both the first conduit section and the second conduitsection.

11. A method according to claim 10, wherein connecting the sleeve portion to both the first conduit section and the second conduit section comprises:25 connecting a first portion of the sleeve portion to an end portion of the first conduitsection and connecting a second portion of the sleeve portion to an end portion of the second conduit section.

12. A method according to any of claims 9 to 11, wherein connecting a first conduit section 30 to a second conduit section comprises:providing a resilient element between the first conduit section and the second conduit section;connecting a first end of the resilient element to the first conduit section; and, connecting a second end of the resilient element to the second conduit section.3513. A method according to any of claims 7 to 12, further comprising drawing at least one electrical conductor through the conduit.28 02 2514. A method according to claim 7, wherein connecting a first joint portion formed of a first metallic material and a second joint portion formed of a second metallic material comprises:5 connecting the first joint portion and the second joint portion via at least one of:friction welding;explosive bonding;resistance welding;ultrasonic welding; and,10 friction and resistance welding,and, wherein connecting bimetallic joints to ends of a first conduit portion and a second conduit portion comprises:connecting bimetallic joints via gas tungsten arc welding to ends of a first conduit portion and a second conduit portion.1515. A method according to claim 9, wherein connecting the first conduit section to the second conduit section comprises connecting the first conduit section to the second conduit section via orbital welding.20 16. A method according to claim 10, wherein connecting the sleeve portion to both the firstconduit section and the second conduit section comprises connecting the sleeve portion to both the first conduit section and the second conduit section via at least one of orbital welding and gas tungsten arc welding.25 17. An aircraft comprising the conduit of claims 1-6.

18. An aircraft according to claim 17, wherein the aircraft is at least partially electricallypowered.30 19. An aircraft according to claim 17 or 18, further comprising:a cryogenic material store for storing cryogenic material; anda fuel cell for provision of electrical power for use in the aircraft.

20. An aircraft according to claim 19, wherein the conduit or conduit network is arranged to 35 transport cryogenic material from the cryogenic material store to the fuel cell.

21. An aircraft according to claim 19 or 20, wherein the conduit or conduit network is arranged to conduct electrical power from the fuel cell.28 02 2527

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