Superconducting cable

Abstract

[Problem] To provide a superconducting cable having excellent insulation of at least each conductor. [Solution] Provided is a superconducting cable having a multi-core structure, the superconducting cable comprising at least a plurality of conductors 10, at least one first pipe 20, and a second pipe 30 accommodating the first pipe 20. At least one of the plurality of conductors 10 is housed in the first pipe 20, and the remaining conductors 10 are housed in the second pipe 30 in an insulated state from each other. This configuration allows each of the conductors 10 to directly contact refrigerant while ensuring insulation between the conductors 10, making it possible to ensure current-carrying performance for higher currents.

Description

Superconducting cable

[0001] The present invention relates to a superconducting cable having a multi-core structure containing a plurality of conductors.

[0002] Conventionally, superconducting cables have been known that use superconducting wires that become superconducting at extremely low temperatures as conductors and are capable of transmitting large currents with low loss. ２ The shift to electric propulsion systems for aircraft and other flying vehicles is being considered to reduce emissions, and there is a growing need for lightweight, highly efficient, and high-power superconducting technology. To realize such propulsion systems, development is underway on superconducting cables capable of carrying large currents, suitable for supplying power to electric motors that will replace jet engines.

[0003] In the following Patent Document 1, the applicant has developed a superconducting cable with a multi-core structure in which insulating spacers are inserted inside a thermal insulation pipe to insulate a plurality of cable cores from one another.

[0004] Patent No. 7383839

[0005] An object of the present invention is to provide a means for ensuring the insulation of each conductor in a superconducting cable containing a plurality of conductors, using a method different from the structure disclosed in Patent Document 1.

[0006] The present invention, which has been made to solve the above-mentioned problems, is a superconducting cable with a multi-core structure, which has at least a plurality of conductors, at least one first tube, and a second tube that houses the first tube, and is configured so that at least one of the plurality of conductors is housed in each of the first tubes, and the remaining conductors are housed in the second tube while being insulated from each other.

[0007] According to the present invention, it is possible to provide a superconducting cable in which each conductor has excellent insulation properties.

[0008] 1 is a schematic end view of a superconducting cable according to Example 1. 2 is a schematic end view showing a current-carrying state of the superconducting cable according to Example 1. 3 is a schematic end view of a superconducting cable according to Example 2. 4 is a schematic end view of a superconducting cable according to Example 4. 5 is a schematic end view of a superconducting cable according to Example 5.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] <1> Overall Configuration (Fig. 1) Fig. 1 is a schematic end view showing the internal structure of the superconducting cable according to Example 1 when cut perpendicular to the cable axial direction. The superconducting cable according to this example (hereinafter also simply referred to as "cable") includes a conductor 10, a first tube 20, a second tube 30, and a third tube 40. Details of each part will be described below.

[0011] <2> Conductor (Fig. 1) The conductor 10 is a member for passing a current through the cable in a superconducting state. In this embodiment, three conductors 10 are provided in the cable.

[0012] <2.1> Conductor Configuration Examples In the present invention, the configuration of the conductor 10 is not particularly limited, and various configurations can be adopted. For example, a laminate formed by stacking multiple tape-shaped superconducting wires can be adopted as the conductor 10 according to the present invention. Here, "tape-shaped" means that the shape is long and planar, and the planar dimensions are sufficiently large compared to the thickness. According to the conductor 10 of this configuration, the cross-sectional area of ​​the conductor 10 in the axial direction can be significantly reduced.

[0013] <2.2> Addition of Insulator to Conductor In the present invention, there are no particular limitations on whether or not an insulator is provided on the outer periphery of the conductor 10, but in a case where the insulation between the conductors 10 is ensured by the first tube 20, as in this embodiment ( FIG. 1 ), it is desirable not to provide a separate insulator on the outer periphery of each conductor 10. This is because an insulator can be a factor that interferes when the superconducting wire that constitutes the conductor 10 is cooled with a refrigerant, and therefore, by having the conductor 10 come into direct contact with the refrigerant without providing an insulator, it also contributes to improving cooling efficiency.

[0014] <2.3> Layout of Conductors In the present invention, the posture and arrangement of the conductors 10 are not particularly limited, and various modes can be adopted.

[0015] <3> First tube (FIG. 1) The first tube 20 is a member for insulating the conductors 10 from each other. The inside of the first tube 20 also functions as a flow path (first flow path 21) for flowing a refrigerant such as liquid nitrogen. In this embodiment, three first tubes 20 are provided, each housing one conductor 10.

[0016] <3.1> Example of the Structure of the First Tube In the present invention, the structure of the first tube 20 is not particularly limited, and various materials and shapes can be used. The first tube 20 preferably has a cold resistance temperature of -50°C or lower, and is preferably flexible and elastic at extremely low temperatures where a refrigerant is used. Examples of materials that satisfy the desired characteristics of the first tube 20 include fluororesin, polyethylene resin, polyphenylsulfone resin, and glass fiber reinforced resin. Alternatively, the resin material forming the first tube 20 may be a rubber substitute material such as polyolefin resin.

[0017] <4> Second Tube (FIG. 1) The second tube 30 is a member for defining a flow path (second flow path 31) for flowing a refrigerant such as liquid nitrogen, separate from the first tube 20. In this embodiment, three first tubes 20 are housed inside the second tube 30, and the second flow paths 31 are provided in a manner completely separated from the three first flow paths 21.

[0018] <4.1> Example of the Configuration of the Second Tube In the present invention, the configuration of the second tube 30 is not particularly limited, and various materials and shapes can be used. Like the first tube 20, the second tube 30 preferably has a cold resistance temperature of −50° C. or lower and is preferably flexible and elastic at extremely low temperatures using a refrigerant. Note that in the present invention, the second tube 30 may be made of the same material as the first tube 20, or a different material.

[0019] <5> Third tube (FIG. 1) The third tube 40 is a member for preventing heat from entering the superconducting cable from the outside. In this embodiment, the second tube 30 is housed inside the third tube 40, and a space 41 between the second tube 30 and the third tube 40 is made into a vacuum state, thereby forming a heat insulating space.

[0020] <5.1> Configuration Examples of the Third Tube In the present invention, the configuration of the third tube 40 is not particularly limited, and various materials and shapes can be used. Like the first tube 20 and the second tube 30, the third tube 40 preferably has a cold resistance temperature of −50° C. or lower and is preferably flexible and elastic at extremely low temperatures using a refrigerant. Note that in the present invention, the third tube 40 may be made of the same material as the first tube 20 and the second tube 30, or a different material.

[0021] <5.2> Addition of a Heat Insulating Section The third pipe 40 may further be provided with a heat insulating section (not shown) made of a material that has heat insulating properties at the extremely low temperatures at which the refrigerant is used. The heat insulating section can be formed by wrapping a heat insulating sheet around the outer periphery of the third pipe 40 or by spraying a heat insulating material made of a urethane resin composition or the like onto the outer periphery of the third pipe 40.

[0022] <6> Image of use (Fig. 2) The state of use of the superconducting cable according to this embodiment will be described with reference to Fig. 2. Fig. 2 shows a state in which a refrigerant flows through the first flow path 21 and the second flow path 31 when current is applied to the superconducting cable. The conductors 10 are reliably insulated from each other by the first pipe 20, and are directly cooled by the refrigerant flowing in the first pipe 20.

[0023] <7> Summary As described above, according to the configuration of this embodiment, by ensuring the insulation between the conductors and by having the refrigerant come into direct contact with each conductor, it is possible to ensure a larger current carrying capacity.

[0024] Second Embodiment A superconducting cable according to a second embodiment of the present invention will be described with reference to FIG.

[0025] <1> Overall configuration In the superconducting cable of Example 1, the number of first tubes 20 was the same as the number of conductors 10, whereas in the superconducting cable of this example, of the three conductors 10 (10a to 10c), two conductors 10a and 10b are housed in the first tubes 20, and the remaining conductor 10c is not housed in the first tube 20 but is housed in the second tube 30.

[0026] <2> Summary In the configuration according to this embodiment, the conductors can be brought into direct contact with the refrigerant while ensuring the insulation of each conductor. Furthermore, compared to the configuration of Example 1, the number of first tubes can be reduced, which contributes to a reduction in the overall weight of the cable.

[0027] A superconducting cable according to a third embodiment of the present invention will be described with reference to FIG.

[0028] <1> Overall configuration The superconducting cable of this embodiment is configured such that, of the four conductors 10 (10a to 10d), two conductors 10a and 10b are insulated from each other by a spacer 50 separately installed inside the second tube 30, and of the remaining two conductors 10c and 10d, one conductor 10c is housed in the first tube 20, and the other conductor 10d is housed in the second tube 30 without being housed in the first tube 20.

[0029] <2> Spacer In the present invention, the spacer 50, like the first tube 20, preferably has a cold resistance temperature of −50° C. or lower and is preferably flexible and elastic at extremely low temperatures using a refrigerant. Furthermore, in the present invention, there is no particular limitation on whether the spacer 50 is in contact with the second tube 30. As shown in FIG. 4 , the spacer 50 may be configured to have a slight gap between the end of the spacer 50 and the inner wall of the second tube 30, or may be configured to abut against the inner wall of the second tube 30. When the spacer 50 abuts against the inner wall of the second tube 30, the second flow path 31 is divided into three flow paths, and the refrigerant can be circulated through each of the divided flow paths. These configurations can be designed appropriately taking into account factors such as the flexibility required for the entire cable.

[0030] <3> Summary In the configuration according to this embodiment, the refrigerant can be brought into direct contact with each conductor while ensuring the insulation of each conductor.

[0031] A superconducting cable according to a fourth embodiment of the present invention will be described with reference to FIG.

[0032] <1> Overall configuration The superconducting cable of this embodiment has three conductors 10 (10a to 10c), of which the first conductor 10a is housed in a first tube 20, the second conductor 10b has an insulating portion 11 on its outer periphery, and the third conductor 10c is not housed in the first tube 20 and is housed in a second tube 30 without having an insulating portion 11 on its outer periphery.

[0033] <2> Insulating portion In the present invention, the insulating portion 11 can be made of a material having insulating properties, heat resistance, and voltage resistance, and can be formed by wrapping, for example, a paper or polyimide strip sheet around the conductor 10.

[0034] <3> Summary In the configuration of this embodiment, although a decrease in the current-carrying performance is expected for conductors with insulating parts due to a decrease in cooling efficiency, it is advantageous in that when there are constraints on the weight or size of the superconducting cable, there is room for design changes such as reducing the weight of the entire cable or reducing the diameter of each tube by, for example, reducing the number of first tubes as much as possible.

[0035] A superconducting cable according to a fifth embodiment of the present invention will be described with reference to FIG.

[0036] <1> Overall Configuration The superconducting cable of this example has a configuration in which the third tube 40 is removed from the configuration of Example 1, and a heat insulating portion 60 is provided on the outer periphery of the second tube 30. As explained in <5.2> above, this heat insulating portion 60 can be made of a material that has heat insulating properties at the extremely low temperatures at which the refrigerant is used.

[0037] <2> Summary In the configuration according to this embodiment, the refrigerant can be brought into direct contact with each conductor while ensuring the insulation of each conductor.

[0038] Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the specific embodiments described above. Various modifications and changes to the specific examples described in the above embodiments are possible within the scope of the gist of the present invention as defined in the claims.

[0039] The superconducting cable of the present invention can be suitably used as a power transmission cable or a power supply cable.

[0040] 10: Conductor 11: Insulation portion 20: First pipe 21: First flow path 30: Second pipe 31: Second flow path 40: Third pipe 41: Space 50: Spacer 60: Heat insulation portion

Claims

1. A superconducting cable having a multi-core structure, comprising at least a plurality of conductors, at least one or more first tubes, and a second tube that houses the first tube, wherein at least one of the plurality of conductors is housed in each of the first tubes, and the remaining conductors are housed in the second tube while being insulated from each other.

2. A superconducting cable according to claim 1, characterized in that no insulating layer is provided around the outer periphery of each of said plurality of conductors.

3. A superconducting cable according to claim 2, characterized in that the number of said first tubes is the same as the number of said plurality of conductors, and said plurality of conductors are housed one by one in said first tube.

4. A superconducting cable according to claim 3, further comprising a third tube that houses the second tube, and a vacuum insulating space is formed between the second tube and the third tube.

5. A superconducting cable according to claim 1, characterized in that a heat insulating portion is provided on the outer periphery of the second tube.

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