WO2014156027A1 - Cooling system - Google Patents

Cooling system Download PDF

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Publication number
WO2014156027A1
WO2014156027A1 PCT/JP2014/001445 JP2014001445W WO2014156027A1 WO 2014156027 A1 WO2014156027 A1 WO 2014156027A1 JP 2014001445 W JP2014001445 W JP 2014001445W WO 2014156027 A1 WO2014156027 A1 WO 2014156027A1
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WO
WIPO (PCT)
Prior art keywords
linear conductor
cooling
wire
cooling system
metal
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PCT/JP2014/001445
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French (fr)
Japanese (ja)
Inventor
芦田　哲哉
広 吉田
幸治 橋本
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三菱電線工業株式会社
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Publication of WO2014156027A1 publication Critical patent/WO2014156027A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G15/00—Cable fittings
    • H02G15/34—Cable fittings for cryogenic cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
    • H01B12/16—Superconductive or hyperconductive conductors, cables, or transmission lines characterised by cooling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Definitions

  • the present invention relates to a cooling system, and more particularly, to a cooling system for a low electrical resistance linear conductor used for electric wires and cables.
  • Patent Document 1 discloses a superconducting material in which silver is 1 ppm or less, sulfur is 0.5 ppm or less, the balance is substantially copper, and the residual resistance ratio is 4000 or more.
  • a copper material for (superconducting) is disclosed.
  • Patent Document 2 is made of a rolled material of high-purity aluminum having a purity of 99.9999% by mass or more, and the surface of the rolled material is subjected to surface polishing treatment, so that it has a low electrical resistivity at an extremely low temperature.
  • a high-purity aluminum material that can express the above is disclosed.
  • a superconducting cable using a superconducting material as a conductor requires a cooling system for cooling and maintaining the conductor at an extremely low temperature.
  • a large-scale device for performing phase conversion of the refrigerant such as refrigerant recovery and re-cooling is necessary, and for example, a robust structure is necessary in preparation for rapid vaporization of the refrigerant in the event of an accident. Therefore, there is a problem that if the system is constructed based on safety, the cost becomes high.
  • the present invention has been made in view of such points, and an object of the present invention is to construct a cooling system in which costs are suppressed as much as possible.
  • the present invention has a metal wire having a circular cross section and a purity of 99.999% by mass or more, and the average crystal grain size in the cross section of the metal wire is 1 of the diameter of the metal wire.
  • the linear conductor formed at / 20 or more is cooled between the first connection portion and the second connection portion.
  • the cooling system according to the present invention has a metal wire having a circular cross section and a purity of 99.999% by mass or more, and the average crystal grain size in the cross section of the metal wire is the diameter of the metal wire.
  • a first connection portion connected to one end of the linear conductor, a second connection portion connected to the other end of the linear conductor, and the first And a cooling device that is provided between the first connection portion and the second connection portion and cools the linear conductor.
  • the crystal defect in a metal wire reduces, and metal
  • the residual resistance ratio (Residual Resistivity Ratio, hereinafter also referred to as “RRR”) of the electric wire becomes higher than 500.
  • a linear conductor having a metal wire of low electrical resistance and high purity as described above has a high thermal conductivity (20 ° C.) of about 200 W / (m ⁇ K) to 420 W / (m ⁇ K).
  • the thermal conductivity is higher than that of a superconducting material such as niobium titanium. Therefore, for example, by cooling a part of the linear conductor to the cryogenic temperature, the cryogenic temperature spreads over the entire linear conductor, and the entire linear conductor is cooled to the cryogenic temperature.
  • the linear conductor constituting the cooling system is configured by using a metal wire that is relatively easy to manufacture and process without using a superconducting material such as niobium titanium, which is relatively difficult to manufacture and process. Therefore, a cooling system with a reduced cost as much as possible is constructed.
  • RRR is the ratio of electrical resistance at a temperature of 293K (normal temperature 20 ° C.) and 4.2K.
  • a plurality of the cooling devices are provided between the first connection portion and the second connection portion so as to be separated from each other along the linear conductor, and the linear conductor is interposed between the plurality of cooling devices.
  • a cold room may be provided so as to surround it.
  • the cold insulation chamber surrounding a part of the linear conductor is provided between the plurality of cooling devices spaced apart from each other, for example, the linear conductor cooled to a cryogenic temperature by each cooling device. Since the cryogenic temperature of the portion spreads through the linear conductor having a relatively high thermal conductivity to the linear conductor portion arranged inside the cold insulation chamber, the entire linear conductor is cooled to the cryogenic temperature, and the linear conductor The cooling device is more compact than the case where the entire length is cooled by the cooling device, and the running cost for cooling is suppressed.
  • the cooling device may be provided such that the linear conductor is cooled via a refrigerant, and the refrigerant from the cooling device flows into the cold insulation chamber adjacent to the cooling device.
  • the refrigerant from the cooling device flows into the cold insulation chamber adjacent to the cooling device, so that the linear conductor is cooled by using the refrigerant from the cooling device inside the cold insulation chamber.
  • the refrigerant leaking from the cooling device is effectively used.
  • One cooling device may be provided between the first connection portion and the second connection portion so as to extend over the entire length of the linear conductor.
  • the linear conductor using the superconductive material is cooled.
  • the diameter of a cable that is provided with a linear conductor therein and is configured so that the linear conductor can be cooled is reduced, and the cooling device becomes compact.
  • the cooling device may include a cooling chamber provided so as to surround the linear conductor, and a refrigerant supply unit that supplies a refrigerant to the inside of the cooling chamber.
  • the cooling device since the cooling device includes the cooling chamber provided so as to surround the linear conductor and the refrigerant supply unit that supplies the refrigerant to the inside of the cooling chamber, the refrigerant is provided on the side surface of the linear conductor. Specifically, a cooling device that cools the linear conductor by bringing them into contact with each other is configured.
  • the linear conductor may be a stranded wire having a plurality of the metal wires, and the plurality of metal wires extending in parallel with each other.
  • the linear conductor is comprised by the strand wire provided so that several metal electric wires may extend mutually in parallel, the intensity
  • the purity of the metal electric wire may be 99.9999% by mass or more.
  • the average crystal grain size in the cross section of the metal wire may be 1/10 or more of the diameter of the metal wire.
  • the average crystal grain diameter in the cross section of a metal electric wire is 1/10 or more of the diameter of a metal electric wire, the crystal defect in a metal electric wire reduces further, and RRR of a linear conductor is still higher.
  • the total content of iron and nickel in the metal wire may be 1 ppm or less.
  • the total content of iron and nickel in a metal wire is 1 ppm or less, for example, it is suitably used in a strong magnetic field having a magnetic flux density of 1 T or more, such as a magnetic resonance imaging diagnostic apparatus or a nuclear magnetic resonance diagnostic apparatus. Is done.
  • the metal wire may be covered with an insulating layer made of polyimide resin.
  • the flexibility of the insulating layer allows even in an extremely low temperature environment (for example, liquid nitrogen temperature: ⁇ 196 ° C.) Breakage due to cracking of the insulating layer covering the metal wire is suppressed. Further, when considering the materials of the metal electric wire and the insulating layer, the thermal expansion coefficient inevitably differs greatly. However, even if the metal wire expands / contracts (expands / shrinks) due to the ambient temperature of the linear conductor, the insulating layer follows the expansion / contraction of the metal wire with its flexibility, while keeping in close contact with the side surface of the metal wire. Even under harsh conditions that repeat an environment and a cryogenic environment, the deterioration of the insulating layer is suppressed.
  • an extremely low temperature environment for example, liquid nitrogen temperature: ⁇ 196 ° C.
  • the cross section is formed in a circular shape and has a metal wire having a purity of 99.999% by mass or more, and the average crystal grain size in the cross section of the metal wire is formed to be 1/20 or more of the diameter of the metal wire. Since the linear conductor is configured to be cooled between the first connection portion and the second connection portion, it is possible to construct a cooling system in which the cost is suppressed as much as possible.
  • FIG. 1 is a cross-sectional view illustrating a cooling system according to the first embodiment.
  • FIG. 2 is a perspective view of a linear conductor constituting the cooling system according to the first embodiment.
  • FIG. 3 is a first example of a schematic diagram illustrating a cross section of the linear conductor according to the first embodiment.
  • FIG. 4 is a second example of a schematic diagram illustrating a cross section of the linear conductor according to the first embodiment.
  • FIG. 5 is a flowchart illustrating the method for manufacturing the linear conductor according to the first embodiment.
  • FIG. 6 is a modification of the flowchart showing the method for manufacturing the linear conductor according to the first embodiment.
  • FIG. 7 is a perspective view of another linear conductor constituting the cooling system according to the first embodiment.
  • FIG. 8 is a flowchart showing a method for manufacturing another linear conductor according to the first embodiment.
  • FIG. 9 is a cross-sectional view illustrating the cooling system according to the second embodiment.
  • Embodiment 1 of the Invention 1 to 8 show Embodiment 1 of the cooling system according to the present invention.
  • FIG. 1 is a cross-sectional view showing the cooling system 50a of the present embodiment.
  • FIG. 2 is a perspective view of the linear conductor 20a constituting the cooling system 50a.
  • FIGS. 3 and 4 are a first example and a second example of schematic views showing a cross section of the linear conductor 20a.
  • 5 and 6 are flowcharts showing a method for manufacturing the linear conductor 20a.
  • FIG. 7 is a perspective view of the linear conductor 20b constituting the cooling system 50a.
  • FIG. 8 is a flowchart showing a method for manufacturing the linear conductor 20b.
  • the cooling system 50 a includes a linear conductor 20, a first connection portion 21 connected to one end in the length direction of the linear conductor 20, and the other in the length direction of the linear conductor 20.
  • a plurality of cold insulation chambers 40 are provided between a pair of adjacent cooling devices 30 to keep the linear conductor 20 cold.
  • a linear conductor 20a see FIG. 2 whose conductor is exposed on the side surface and a linear conductor 20b (see FIG. 7) whose conductor is not exposed on the side surface are illustrated.
  • the linear conductor 20a is a stranded wire in which a plurality of (for example, seven) metal wires 10 provided so as to extend in parallel with each other are twisted together.
  • the metal wire 10 has a circular cross section and is made of, for example, copper, aluminum, silver, or the like.
  • the purity of the metal of the metal electric wire 10 is 99.999 mass% or more, preferably 99.9999 mass% or more, more preferably 99.99999 mass% or more.
  • the average crystal grain size in the cross section of the metal wire 10 is 1/20 or more of the diameter of the metal wire 10 (for example, about 1/10, see FIG. 3). / 10 or more (for example, about 1/5, see FIG. 4).
  • the total content of iron and nickel in the metal wire 10 is 1 ppm or less.
  • the metal electric wire 10 has a high thermal conductivity of about 380 W / (m ⁇ K) in the case of copper, about 200 W / (m ⁇ K) in the case of aluminum, and about 420 W / (m ⁇ K) in the case of silver (20 ° C).
  • the thermal conductivity is measured by a laser flash method based on JIS R 1611.
  • the linear conductor 20b is a stranded wire obtained by twisting a plurality of (for example, seven) insulated wires 15 provided so as to extend in parallel to each other.
  • the insulated wire 15 includes a metal wire 10 and a polyimide resin insulating layer 11 provided so as to cover the side surface of the metal wire 10.
  • the insulating layer 11 is made of, for example, a block copolymerized polyimide.
  • the block copolymerized polyimide has, for example, a siloxane bond in the main chain of the polyimide and an anionic group in the molecule. ing.
  • the block copolymerized polyimide has, for example, a weight average molecular weight of 45,000 to 90,000 and a number average molecular weight of 20,000 to 40,000.
  • the film thickness of the insulating layer 11 is, for example, about 1 ⁇ m to 50 ⁇ m.
  • the first connection portion 21 and the second connection portion 22 are, for example, copper connection terminals, and are fixed to the linear conductor 20 by crimping or compression.
  • the cooling device 30 includes a cooling chamber 31 provided so as to surround a part of the linear conductor 20, and a refrigerant supply unit 32 connected to a side surface of a cylindrical body described later of the cooling chamber 31. It has.
  • the cooling chamber 31 includes, for example, a cylindrical body provided around the linear conductor 20, and a pair of annular bodies that are respectively provided in a pair of openings of the cylindrical body and into which the linear conductor 20 is inserted. An almost closed space is formed.
  • the cooling chamber 31 has a structure such as a double wall made of stainless steel in which a vacuum heat insulating layer is formed between the walls.
  • the refrigerant supply unit 32 is provided so as to supply, for example, a refrigerant C such as liquid helium or liquid nitrogen into the cooling chamber 31.
  • the cooling device 30 that cools the linear conductor 20 by bringing the liquid refrigerant C into contact with the linear conductor 20 is exemplified, but the cooling device that cools the linear conductor 20 includes steam, refrigerant, and the like.
  • the cold insulation chamber 40 connects a pair of adjacent cooling devices 30 and is provided in a cylindrical shape so as to surround a part of the linear conductor 20.
  • the cold insulation chamber 40 is composed of, for example, a stainless steel double tube in which a vacuum heat insulating layer is formed between the tubes.
  • the cooling system 50 a configured as described above cools the linear conductors 20 arranged inside the cooling chambers 31 of the respective cooling devices 30 with the refrigerant C, and the cooling chambers 40 adjacent to the cooling chambers 31.
  • the refrigerant C from the cooling chamber 31 flows into the interior, so that the linear conductor 20 is not only kept cool but also cooled inside the cold storage chamber 40.
  • the manufacturing method of the linear conductor 20a which comprises the cooling system 50a of this embodiment is demonstrated.
  • the manufacturing method of this embodiment includes a preparation process, a heat treatment process, and a molding process.
  • a billet having a purity of 99.999% by mass or more is produced by casting electrolytic copper, and then the produced billet is drawn in a plurality of steps. Make a copper wire of about 1mm to 3.2mm.
  • the copper electric wire in the furnace is at 300 ° C or higher for 1 hour or longer (preferably 500 ° C or higher for 1 hour or longer).
  • Heat treatment in a reducing atmosphere such as hydrogen, an inert gas atmosphere such as nitrogen, or a vacuum atmosphere under certain conditions allows the average crystal grain size in the cross section of the copper wire to be 1/20 or more, preferably 1/10 of the diameter of the copper wire. That's it.
  • the manufacturing method which performs the batch process which heat-processes a copper electric wire collectively was illustrated, for example, the copper electric wire produced at the said preparatory process is carried into a cylindrical pipe annealing furnace as it is, and By carrying the copper wire in the furnace, it is carried out in a reducing atmosphere such as hydrogen or an inert gas atmosphere such as nitrogen under conditions of 500 ° C. or higher and 30 seconds or longer (preferably 600 ° C. or higher and 30 seconds or longer). You may heat-process continuously.
  • a reducing atmosphere such as hydrogen or an inert gas atmosphere such as nitrogen under conditions of 500 ° C. or higher and 30 seconds or longer (preferably 600 ° C. or higher and 30 seconds or longer).
  • a plurality of copper wires heat-treated in the heat treatment step are prepared, and the plurality of copper wires are twisted together to produce a stranded wire (linear conductor 20a).
  • the linear conductor 20a of this embodiment can be manufactured.
  • molding process after performing a heat treatment process was illustrated, after performing the preparation process mentioned above, as shown in FIG.
  • the above-described heat treatment step may be performed.
  • the linear conductor 20b of this embodiment is the heat-treated copper electric wire, after performing the preparation process and heat treatment process which were mentioned above, as shown in FIG. 8, similarly to the manufacturing method of the line conductor 20a mentioned above.
  • the insulating layer 11 is formed by performing electrodeposition coating or dip coating on the side surface of the film and subsequent baking treatment, and finally, the molding process described above can be performed.
  • Example 1 a copper wire having a purity of 99.999 mass%, 99.9999 mass%, or 99.999998 mass% was used, and the above-described linear conductor was used.
  • a single-wire copper wire having a diameter of 0.32 mm was manufactured by performing heat treatment under predetermined conditions.
  • Comparative Examples 1 and 2 a copper wire having a purity of 99.99% by mass and 99.999% by mass was used, and a single-wire copper wire having a diameter of 0.32 mm was produced by performing heat treatment under predetermined conditions. And about each produced copper electric wire, the crystal grain size, RRR, and the total content of iron and nickel were evaluated.
  • the crystal grain size that is, the average crystal grain size was calculated based on the formula ⁇ (average crystal area / ⁇ ) ⁇ ⁇ 2 from the microstructure of the cross section of the copper electric wire.
  • the RRR, room temperature electrical resistance R 293 K at (20 °C 293K), and the electrical resistance R 4.2 K in liquid helium temperature (4.2 K) as measured by the four probe method, R 293 K / R 4.2 K of Calculated from the formula.
  • the total content of iron and nickel was measured by glow discharge mass spectrometry using VG9000 manufactured by Thermo Fisher Scientific Co., Ltd.
  • the purity of copper is also determined by glow discharge mass spectrometry. Copper content or impurities (elements such as silver, aluminum, arsenic, bismuth, chromium, iron, magnesium, sodium, nickel, sulfur, antimony, silicon) It was calculated by measuring the content of.
  • Example 1 Although 99.99 mass% copper wire was heat-treated at 500 ° C. for 1 hour (3600 seconds), the RRR was about 400, but in Examples 1 to 3, It was confirmed that the RRR was increased to about 1500 to 4600 when heat-treated at a temperature of 300 ° C. or higher for 1 hour or longer using a higher purity 99.999 mass% copper wire. Moreover, in Example 4 which performed the continuous process, it was confirmed that RRR will become high to about 2800 only by heat-processing on the conditions for 30 second at 500 degreeC. Furthermore, in Example 5 using a 99.9999 mass% copper wire, it was confirmed that the RRR increases to about 4500 just by heat treatment at 500 ° C. for 30 seconds.
  • Example 6 using a 99.99998% by mass copper wire of higher purity, it was confirmed that the RRR was increased to about 5400 just by heat treatment at 500 ° C. for 30 seconds. Similarly, in Examples 7 to 9 using 99.99998% by mass of copper wire, it was confirmed that the RRR was increased to about 4800 to 9800 by heat treatment at 300 ° C. or more for 1 hour or more.
  • the average crystal grain size is about 1/22 and 1/21 of the diameter of the copper wire in Comparative Examples 1 and 2, but in Examples 1 to 9, 1/16 to 1 of the diameter of the copper wire. It was about / 6, and it was confirmed that it became 1/20 (preferably 1/10) or more of the diameter of the copper electric wire.
  • the total content of iron and nickel is 1.1 and 0.3 ppm in Comparative Examples 1 and 2, but 0.02 to 0.5 ppm in Examples 1 to 9 and 1 ppm or less. It was confirmed.
  • Example 9 As an example, using a copper wire having a purity of 99.9999% by mass and a diameter of 1.0 mm, the heat treatment of Example 9 described above was performed, and then a polyimide resin was electrodeposited on the side surface to obtain a thickness of 10 ⁇ m. An insulated wire having an insulating layer made of a polyimide resin was prepared. In addition, as a comparative example, after performing the heat treatment of Example 9 described above using a copper wire having a purity of 99.9999% by mass and a diameter of 1.0 mm, the epoxy resin is dip-coated on the side surface to obtain a thickness. An insulated wire having an insulating layer made of epoxy resin of about 10 ⁇ m was produced.
  • Each of the manufactured insulated wires was tightly wound 10 times in a coil shape with an inner diameter of 1 mm to prepare test specimens, and each test specimen was immersed in liquid nitrogen for 10 minutes, and then returned to room temperature (20 ° C.). The surface of the insulating layer of each test specimen was observed with a 20x magnifier to check for cracks.
  • a copper wire is exemplified as the metal wire, but the present invention can also be applied to a metal wire made of aluminum or silver.
  • the average crystal grain size in the cross section of each metal wire 10 having a purity of 99.999% by mass or more is 1/20 or more of the diameter of the metal wire 10. Therefore, crystal defects in the metal wire 10 are reduced, and the RRR of the metal wire 10 is increased to 500 or more.
  • the linear conductor 20 having such a low-electric resistance and high-purity metal wire 10 has a high thermal conductivity (20 ° C.) of about 200 W / (m ⁇ K) to 420 W / (m ⁇ K). Therefore, it has a higher thermal conductivity than a superconducting material such as niobium titanium even at an extremely low temperature of about 4.2K.
  • the cooling device 30 which cools the linear conductor 20 between the 1st connection part 21 and the 2nd connection part 22 can be simplified.
  • the linear conductor 20 constituting the cooling system 50a uses, for example, the metal electric wire 10 that is relatively easy to manufacture and process without using a superconductive material such as niobium titanium that is relatively difficult to manufacture and process. Therefore, it is possible to construct the cooling system 50a with the cost reduced as much as possible.
  • the cold insulation chamber 40 that surrounds a part of the linear conductor 20 is provided between the plurality of cooling devices 30 that are separated from each other.
  • the entire conductor 20 is cooled to a very low temperature, and the cooling device 30 can be made more compact than the case where the linear conductor is cooled by the cooling device over the entire length, and the running cost related to cooling can be suppressed.
  • the refrigerant C from the cooling device 30 flows into the cold insulating chamber 40 adjacent to the cooling device 30, so that the cooling device is provided inside the cold insulating chamber 40.
  • the linear conductor 20 is cooled by using the refrigerant C from the refrigerant 30, and the refrigerant C leaked from the cooling device 30 can be used effectively.
  • the linear conductor 20 is comprised by the strand wire provided so that the several metal electric wire 10 might mutually extend in parallel, when a single wire metal electric wire is used As a result, the strength of the linear conductor 20 can be increased.
  • the magnetic flux density of 1 T or more such as a magnetic resonance imaging diagnostic apparatus or a nuclear magnetic resonance diagnostic apparatus, is used. It can be suitably used in a strong magnetic field.
  • the metal electric wire 10 constituting the linear conductor 20 is a high-purity copper electric wire
  • the conductor is not a superconducting material, and the connection technology is established. Since it is an electric wire, it can be easily connected to a peripheral device.
  • the cooling system 50a using the linear conductor 20b of this embodiment since the metal electric wire 10 is covered with the insulating layer 11 made of polyimide resin, the flexibility of the insulating layer 11 allows a cryogenic environment ( Even at a liquid nitrogen temperature of ⁇ 196 ° C., breakage due to cracking of the insulating layer 11 covering the metal wire 10 can be suppressed. In addition, when considering the materials of the metal wire 10 and the insulating layer 11, the thermal expansion coefficients are inevitably greatly different.
  • the insulating layer 11 can be expanded and contracted while being in close contact with the side surface of the metal wire 10 due to its flexibility. Since it follows, the deterioration of the insulating layer 11 can be suppressed even under harsh conditions in which the normal temperature environment and the cryogenic environment are repeated.
  • FIG. 9 is a cross-sectional view showing the cooling system 50b of the present embodiment.
  • the same portions as those in FIGS. 1 to 8 are denoted by the same reference numerals, and detailed description thereof is omitted.
  • the cooling system 50a including the plurality of cooling devices 30 is illustrated, but in the present embodiment, the cooling system 50b including one cooling device 35 is illustrated.
  • the cooling system 50 b includes a linear conductor 20 composed of the linear conductor 20 a or 20 b of the first embodiment, and a first connection portion connected to one end in the length direction of the linear conductor 20. 21, provided between the second connection part 22 connected to the other end in the length direction of the linear conductor 20, and the first connection part 21 and the second connection part 22, for cooling the linear conductor 20.
  • the cooling device 35 is provided.
  • the cooling device 35 includes a cooling chamber 33 provided so as to surround the entire linear conductor 20, and a refrigerant supply unit 34 connected to a side surface of a cylindrical body described later of the cooling chamber 33. I have.
  • the cooling chamber 33 includes, for example, a cylindrical body provided around the linear conductor 20 and a pair of annular bodies that are provided in a pair of openings of the cylindrical body and into which the linear conductor 20 is inserted, An almost closed space is formed.
  • the cooling chamber 33 has a structure such as a double wall made of stainless steel in which a vacuum heat insulating layer is formed between the walls.
  • the refrigerant supply unit 34 is provided so as to supply, for example, a refrigerant C such as liquid helium into the cooling chamber 33.
  • the cooling system 50b having the above-described configuration is configured to cool the linear conductor 20 disposed inside the cooling chamber 31 of the cooling device 35 with the refrigerant C as shown in FIG.
  • each of the metal wires 10 includes a plurality of metal wires 10 having a circular cross section and a purity of 99.999% by mass or more.
  • the linear conductor 20 formed so that the average crystal grain size in the cross section of the electric wire 10 is 1/20 or more of the diameter of the metal electric wire 10 is cooled between the first connecting portion 21 and the second connecting portion 22. Therefore, it is possible to construct the cooling system 50b whose cost is suppressed as much as possible.
  • the single cooling device 35 is provided between the first connection portion 21 and the second connection portion 22 so as to extend over the entire length of the linear conductor 20, so Rather than cooling a linear conductor using a conductive material, the diameter of the cable configured to be equipped with the linear conductor 20 and capable of cooling the linear conductor 20 is reduced, and the cooling device 35 is made compact. Can do.
  • the cooling system provided with a stranded wire conductor composed of seven single wires has been exemplified.
  • the present invention is not limited to a single wire other than seven stranded wires or one single wire.
  • the present invention can also be applied to a cooling system including a linear conductor and a cooling system provided with a plurality of linear conductors extending in parallel with each other.
  • a cooling system including a round wire conductor having a circular cross section is exemplified, but the present invention is a linear conductor formed in a circle having a flat cross section, The present invention can also be applied to a cooling system including a flat wire conductor having a rectangular cross section or a tubular conductor.
  • the present invention can construct a cooling system in which the cost is suppressed as much as possible. Therefore, the present invention is useful for a (electric power) cable that requires low electrical resistance.

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  • Containers, Films, And Cooling For Superconductive Devices (AREA)
  • Cooling Or The Like Of Electrical Apparatus (AREA)
  • Processing Of Terminals (AREA)
  • Gas Or Oil Filled Cable Accessories (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)

Abstract

The present invention is provided with: a linear conductor (20) that has a cross section formed into a circular shape, has a metal wire having a purity of at least 99.999 mass%, and is formed having an average crystal grain size in a cross section of the metal wire that is at least 1/20 the diameter of the metal wire; a first connection section (21) connected to one end of the linear conductor (20); a second connection section (22) connected to the other end of the linear conductor (20); and a cooling device (30) that is provided between the first connection section (21) and second connection section (22) and that cools the linear conductor (20).

Description

冷却システムCooling system
　本発明は、冷却システムに関し、特に、電線やケーブルに用いる低電気抵抗の線状導体の冷却システムに関するものである。 The present invention relates to a cooling system, and more particularly, to a cooling system for a low electrical resistance linear conductor used for electric wires and cables.
　近年のエネルギー問題に伴って、電線やケーブルでは、低損失化が要望されている。 With the recent energy problems, there is a demand for low loss in electric wires and cables.
　例えば、特許文献１には、銀が１ｐｐｍ以下であり、イオウが０．５ｐｐｍ以下であり、残部が実質的に銅からなり、かつ残留抵抗比が４０００以上である高純度銅よりなる、超電導（超伝導）用の銅材が開示されている。 For example, Patent Document 1 discloses a superconducting material in which silver is 1 ppm or less, sulfur is 0.5 ppm or less, the balance is substantially copper, and the residual resistance ratio is 4000 or more. A copper material for (superconducting) is disclosed.
　また、特許文献２には、純度９９．９９９９質量％以上である高純度アルミニウムの圧延材からなり、その圧延材の表面に表面研磨処理が施されていることにより、極低温において低い電気抵抗率を発現しうる、高純度アルミニウム材が開示されている。 Further, Patent Document 2 is made of a rolled material of high-purity aluminum having a purity of 99.9999% by mass or more, and the surface of the rolled material is subjected to surface polishing treatment, so that it has a low electrical resistivity at an extremely low temperature. A high-purity aluminum material that can express the above is disclosed.
特公平７－１０７１８１号公報Japanese Examined Patent Publication No. 7-107181 特開２０１０－１５９４４６号公報JP 2010-159446 A
　ところで、超伝導材料を導体に用いた超伝導ケーブルでは、導体を極低温に冷却及び維持するための冷却システムが必要である。ここで、この冷却システムでは、冷媒の回収及び再冷却という冷媒の相変換を行うための大掛かり装置が必要であり、また、例えば、事故時の急激な冷媒の気化に備えて堅牢な構造が必要であるので、安全性を踏まえてシステムを構築すると、コストが高くなってしまうという問題があった。 Incidentally, a superconducting cable using a superconducting material as a conductor requires a cooling system for cooling and maintaining the conductor at an extremely low temperature. Here, in this cooling system, a large-scale device for performing phase conversion of the refrigerant such as refrigerant recovery and re-cooling is necessary, and for example, a robust structure is necessary in preparation for rapid vaporization of the refrigerant in the event of an accident. Therefore, there is a problem that if the system is constructed based on safety, the cost becomes high.
　本発明は、かかる点に鑑みてなされたものであり、その目的とするところは、可及的にコストが抑制された冷却システムを構築することにある。 The present invention has been made in view of such points, and an object of the present invention is to construct a cooling system in which costs are suppressed as much as possible.
　上記目的を達成するために、本発明は、横断面が円形に形成され純度９９．９９９質量％以上の金属電線を有し、金属電線の横断面における平均結晶粒径が金属電線の直径の１／２０以上に形成された線状導体を第１接続部及び第２接続部の間で冷却するようにしたものである。 In order to achieve the above object, the present invention has a metal wire having a circular cross section and a purity of 99.999% by mass or more, and the average crystal grain size in the cross section of the metal wire is 1 of the diameter of the metal wire. The linear conductor formed at / 20 or more is cooled between the first connection portion and the second connection portion.
　具体的に本発明に係る冷却システムは、横断面が円形に形成され、純度９９．９９９質量％以上の金属電線を有し、該金属電線の横断面における平均結晶粒径が該金属電線の直径の１／２０以上に形成された線状導体と、上記線状導体の一方端に接続された第１接続部と、上記線状導体の他方端に接続された第２接続部と、上記第１接続部及び第２接続部の間に設けられ、上記線状導体を冷却する冷却装置とを備えている。 Specifically, the cooling system according to the present invention has a metal wire having a circular cross section and a purity of 99.999% by mass or more, and the average crystal grain size in the cross section of the metal wire is the diameter of the metal wire. Of the linear conductor, a first connection portion connected to one end of the linear conductor, a second connection portion connected to the other end of the linear conductor, and the first And a cooling device that is provided between the first connection portion and the second connection portion and cools the linear conductor.
　上記の構成によれば、純度９９．９９９質量％以上の金属電線の横断面における平均結晶粒径が金属電線の直径の１／２０以上であるので、金属電線における結晶欠陥が減少して、金属電線の残留抵抗比（Residual Resistivity Ratio、以下、「ＲＲＲ」とも称する）が５００以上に高くなる。ここで、上記のような低電気抵抗で高純度の金属電線を有する線状導体は、２００Ｗ／（ｍ・Ｋ）～４２０Ｗ／（ｍ・Ｋ）程度の高い熱伝導率（２０℃）を有しているので、例えば、４．２Ｋ程度の極低温でもニオブチタンなどの超伝導材料よりも高い熱伝導率を有することになる。そのため、例えば、線状導体の一部を極低温に冷却することにより、その極低温が線状導体全体に広がって、線状導体全体が極低温に冷却される。これにより、第１接続部及び第２接続部の間で線状導体を冷却する冷却装置を簡素化することが可能になる。しかも、冷却システムを構成する線状導体は、例えば、製造及び加工が比較的に困難なニオブチタンなどの超伝導材料を用いることなく、製造及び加工が比較的に容易な金属電線を用いて構成されているので、可及的にコストが抑制された冷却システムが構築される。なお、ＲＲＲは、温度２９３Ｋ（常温２０℃）及び４．２Ｋでの電気抵抗の比である。 According to said structure, since the average crystal grain diameter in the cross section of a metal wire with a purity of 99.999 mass% or more is 1/20 or more of the diameter of a metal wire, the crystal defect in a metal wire reduces, and metal The residual resistance ratio (Residual Resistivity Ratio, hereinafter also referred to as “RRR”) of the electric wire becomes higher than 500. Here, a linear conductor having a metal wire of low electrical resistance and high purity as described above has a high thermal conductivity (20 ° C.) of about 200 W / (m · K) to 420 W / (m · K). Therefore, for example, even at a cryogenic temperature of about 4.2 K, the thermal conductivity is higher than that of a superconducting material such as niobium titanium. Therefore, for example, by cooling a part of the linear conductor to the cryogenic temperature, the cryogenic temperature spreads over the entire linear conductor, and the entire linear conductor is cooled to the cryogenic temperature. This makes it possible to simplify the cooling device that cools the linear conductor between the first connection portion and the second connection portion. Moreover, the linear conductor constituting the cooling system is configured by using a metal wire that is relatively easy to manufacture and process without using a superconducting material such as niobium titanium, which is relatively difficult to manufacture and process. Therefore, a cooling system with a reduced cost as much as possible is constructed. RRR is the ratio of electrical resistance at a temperature of 293K (normal temperature 20 ° C.) and 4.2K.
　上記第１接続部及び第２接続部の間には、上記冷却装置が上記線状導体に沿って互いに離間するように複数設けられ、上記複数の冷却装置の間には、上記線状導体を囲むように保冷室が設けられていてもよい。 A plurality of the cooling devices are provided between the first connection portion and the second connection portion so as to be separated from each other along the linear conductor, and the linear conductor is interposed between the plurality of cooling devices. A cold room may be provided so as to surround it.
　上記の構成によれば、互いに離間する複数の冷却装置の間に線状導体の一部を囲む保冷室が設けられているので、例えば、各冷却装置で極低温に冷却された線状導体の部分の極低温が保冷室の内部に配置する線状導体の部分に比較的高い熱伝導率を有する線状導体を介して広がることにより、線状導体全体が極低温に冷却され、線状導体を全長にわたって冷却装置で冷却する場合よりも、冷却装置がコンパクトになると共に、冷却に関するランニングコストが抑制される。 According to the above configuration, since the cold insulation chamber surrounding a part of the linear conductor is provided between the plurality of cooling devices spaced apart from each other, for example, the linear conductor cooled to a cryogenic temperature by each cooling device. Since the cryogenic temperature of the portion spreads through the linear conductor having a relatively high thermal conductivity to the linear conductor portion arranged inside the cold insulation chamber, the entire linear conductor is cooled to the cryogenic temperature, and the linear conductor The cooling device is more compact than the case where the entire length is cooled by the cooling device, and the running cost for cooling is suppressed.
　上記冷却装置は、冷媒を介して上記線状導体を冷却し、該冷却装置に隣り合う上記保冷室に該冷却装置からの冷媒が流れ込むように設けられていてもよい。 The cooling device may be provided such that the linear conductor is cooled via a refrigerant, and the refrigerant from the cooling device flows into the cold insulation chamber adjacent to the cooling device.
　上記の構成によれば、冷却装置では、それに隣り合う保冷室に冷却装置からの冷媒が流れ込むようになっているので、保冷室の内部において、冷却装置からの冷媒を用いて線状導体が冷却されることになり、例えば、冷却装置から漏れ出た冷媒が有効利用される。 According to the above configuration, in the cooling device, the refrigerant from the cooling device flows into the cold insulation chamber adjacent to the cooling device, so that the linear conductor is cooled by using the refrigerant from the cooling device inside the cold insulation chamber. For example, the refrigerant leaking from the cooling device is effectively used.
　上記第１接続部及び第２接続部の間には、上記冷却装置が上記線状導体の全長にわたるように１つ設けられていてもよい。 One cooling device may be provided between the first connection portion and the second connection portion so as to extend over the entire length of the linear conductor.
　上記の構成によれば、第１接続部及び第２接続部の間では、線状導体の全長にわたるように１つの冷却装置が設けられているので、超伝導材料を用いた線状導体を冷却する場合よりも、例えば、線状導体を内部に備え、線状導体を冷却可能に構成されたケーブルの直径が小さくなり、冷却装置がコンパクトになる。 According to the above configuration, since one cooling device is provided between the first connection portion and the second connection portion so as to extend over the entire length of the linear conductor, the linear conductor using the superconductive material is cooled. For example, the diameter of a cable that is provided with a linear conductor therein and is configured so that the linear conductor can be cooled is reduced, and the cooling device becomes compact.
　上記冷却装置は、上記線状導体を囲むように設けられた冷却室と、該冷却室の内部に冷媒を供給する冷媒供給部とを備えていてもよい。 The cooling device may include a cooling chamber provided so as to surround the linear conductor, and a refrigerant supply unit that supplies a refrigerant to the inside of the cooling chamber.
　上記の構成によれば、冷却装置が線状導体を囲むように設けられた冷却室とその冷却室の内部に冷媒を供給する冷媒供給部とを備えているので、線状導体の側面に冷媒を接触させて線状導体を冷却する冷却装置が具体的に構成される。 According to the above configuration, since the cooling device includes the cooling chamber provided so as to surround the linear conductor and the refrigerant supply unit that supplies the refrigerant to the inside of the cooling chamber, the refrigerant is provided on the side surface of the linear conductor. Specifically, a cooling device that cools the linear conductor by bringing them into contact with each other is configured.
　上記線状導体は、上記金属電線を複数有し、該複数の金属電線が互いに並行に延びるように設けられた撚り線であってもよい。 The linear conductor may be a stranded wire having a plurality of the metal wires, and the plurality of metal wires extending in parallel with each other.
　上記の構成によれば、複数の金属電線が互いに並行に延びるように設けられた撚り線により線状導体が構成されているので、単線の金属電線を用いた場合よりも線状導体の強度が高くなる。 According to said structure, since the linear conductor is comprised by the strand wire provided so that several metal electric wires may extend mutually in parallel, the intensity | strength of a linear conductor is more than the case where a single wire metal electric wire is used. Get higher.
　上記金属電線の純度は、９９．９９９９質量％以上であってもよい。 The purity of the metal electric wire may be 99.9999% by mass or more.
　上記の構成によれば、金属電線の純度がいっそう高くなるので、線状導体のＲＲＲがいっそう高くなる。 According to the above configuration, since the purity of the metal electric wire is further increased, the RRR of the linear conductor is further increased.
　上記金属電線の横断面における平均結晶粒径は、上記金属電線の直径の１／１０以上であってもよい。 The average crystal grain size in the cross section of the metal wire may be 1/10 or more of the diameter of the metal wire.
　上記の構成によれば、金属電線の横断面における平均結晶粒径が金属電線の直径の１／１０以上であるので、金属電線における結晶欠陥がいっそう減少して、線状導体のＲＲＲがいっそう高くなる。 According to said structure, since the average crystal grain diameter in the cross section of a metal electric wire is 1/10 or more of the diameter of a metal electric wire, the crystal defect in a metal electric wire reduces further, and RRR of a linear conductor is still higher. Become.
　上記金属電線における鉄及びニッケルの総含有量は、１ｐｐｍ以下であってもよい。 The total content of iron and nickel in the metal wire may be 1 ppm or less.
　上記の構成によれば、金属電線における鉄及びニッケルの総含有量が１ｐｐｍ以下であるので、例えば、磁気共鳴画像診断装置や核磁気共鳴診断装置などの磁束密度１Ｔ以上の強磁場で好適に使用される。 According to said structure, since the total content of iron and nickel in a metal wire is 1 ppm or less, for example, it is suitably used in a strong magnetic field having a magnetic flux density of 1 T or more, such as a magnetic resonance imaging diagnostic apparatus or a nuclear magnetic resonance diagnostic apparatus. Is done.
　上記金属電線は、ポリイミド樹脂製の絶縁層で被覆されていてもよい。 The metal wire may be covered with an insulating layer made of polyimide resin.
　上記の構成によれば、金属電線がポリイミド樹脂製の絶縁層で被覆されているので、その絶縁層の柔軟性により、極低温環境（例えば、液体窒素温度：－１９６℃）であっても、金属電線を被覆する絶縁層の割れによる破壊が抑制される。また、金属電線と絶縁層とでは、それらの材質を考慮すると、熱膨張係数が必然的に大きく異なってしまう。しかしながら、線状導体の環境温度に起因して金属電線が伸縮（膨張／収縮）しても、絶縁層がその柔軟性により金属電線の側面に密着したまま金属電線の伸縮に追従するので、常温環境と極低温環境とを繰り返すような過酷な条件下であっても、絶縁層の劣化が抑制される。 According to the above configuration, since the metal electric wire is covered with the insulating layer made of polyimide resin, the flexibility of the insulating layer allows even in an extremely low temperature environment (for example, liquid nitrogen temperature: −196 ° C.) Breakage due to cracking of the insulating layer covering the metal wire is suppressed. Further, when considering the materials of the metal electric wire and the insulating layer, the thermal expansion coefficient inevitably differs greatly. However, even if the metal wire expands / contracts (expands / shrinks) due to the ambient temperature of the linear conductor, the insulating layer follows the expansion / contraction of the metal wire with its flexibility, while keeping in close contact with the side surface of the metal wire. Even under harsh conditions that repeat an environment and a cryogenic environment, the deterioration of the insulating layer is suppressed.
　本発明によれば、横断面が円形に形成され純度９９．９９９質量％以上の金属電線を有し、金属電線の横断面における平均結晶粒径が金属電線の直径の１／２０以上に形成された線状導体を第１接続部及び第２接続部の間で冷却するように構成されているので、可及的にコストが抑制された冷却システムを構築することができる。 According to the present invention, the cross section is formed in a circular shape and has a metal wire having a purity of 99.999% by mass or more, and the average crystal grain size in the cross section of the metal wire is formed to be 1/20 or more of the diameter of the metal wire. Since the linear conductor is configured to be cooled between the first connection portion and the second connection portion, it is possible to construct a cooling system in which the cost is suppressed as much as possible.
図１は、実施形態１に係る冷却システムを示す断面図である。FIG. 1 is a cross-sectional view illustrating a cooling system according to the first embodiment. 図２は、実施形態１に係る冷却システムを構成する線状導体の斜視図である。FIG. 2 is a perspective view of a linear conductor constituting the cooling system according to the first embodiment. 図３は、実施形態１に係る線状導体の横断面を示す模式図の第１例である。FIG. 3 is a first example of a schematic diagram illustrating a cross section of the linear conductor according to the first embodiment. 図４は、実施形態１に係る線状導体の横断面を示す模式図の第２例である。FIG. 4 is a second example of a schematic diagram illustrating a cross section of the linear conductor according to the first embodiment. 図５は、実施形態１に係る線状導体の製造方法を示すフローチャートである。FIG. 5 is a flowchart illustrating the method for manufacturing the linear conductor according to the first embodiment. 図６は、実施形態１に係る線状導体の製造方法を示すフローチャートの変形例である。FIG. 6 is a modification of the flowchart showing the method for manufacturing the linear conductor according to the first embodiment. 図７は、実施形態１に係る冷却システムを構成する他の線状導体の斜視図である。FIG. 7 is a perspective view of another linear conductor constituting the cooling system according to the first embodiment. 図８は、実施形態１に係る他の線状導体の製造方法を示すフローチャートである。FIG. 8 is a flowchart showing a method for manufacturing another linear conductor according to the first embodiment. 図９は、実施形態２に係る冷却システムを示す断面図である。FIG. 9 is a cross-sectional view illustrating the cooling system according to the second embodiment.
　以下、本発明の実施形態を図面に基づいて詳細に説明する。なお、本発明は、以下の各実施形態に限定されるものではない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments.
　《発明の実施形態１》
　図１～図８は、本発明に係る冷却システムの実施形態１を示している。ここで、図１は、本実施形態の冷却システム５０ａを示す断面図である。また、図２は、冷却システム５０ａを構成する線状導体２０ａの斜視図である。また、図３及び図４は、線状導体２０ａの横断面を示す模式図の第１例及び第２例である。また、図５及び図６は、線状導体２０ａの製造方法を示すフローチャートである。また、図７は、冷却システム５０ａを構成する線状導体２０ｂの斜視図である。また、図８は、線状導体２０ｂの製造方法を示すフローチャートである。 Embodiment 1 of the Invention
1 to 8 show Embodiment 1 of the cooling system according to the present invention. Here, FIG. 1 is a cross-sectional view showing the cooling system 50a of the present embodiment. FIG. 2 is a perspective view of the linear conductor 20a constituting the cooling system 50a. FIGS. 3 and 4 are a first example and a second example of schematic views showing a cross section of the linear conductor 20a. 5 and 6 are flowcharts showing a method for manufacturing the linear conductor 20a. FIG. 7 is a perspective view of the linear conductor 20b constituting the cooling system 50a. FIG. 8 is a flowchart showing a method for manufacturing the linear conductor 20b.
　冷却システム５０ａは、図１に示すように、線状導体２０と、線状導体２０の長さ方向の一方端に接続された第１接続部２１と、線状導体２０の長さ方向の他方端に接続された第２接続部２２と、第１接続部２１及び第２接続部２２の間に互いに離間するように設けられ、線状導体２０を冷却するための複数の冷却装置３０と、隣り合う一対の冷却装置３０の間にそれぞれ設けられ、線状導体２０を保冷するための複数の保冷室４０とを備えている。なお、本実施形態では、線状導体２０として、側面に導体が露出する線状導体２０ａ（図２参照）と、側面に導体が露出しない線状導体２０ｂ（図７参照）とを例示する。 As shown in FIG. 1, the cooling system 50 a includes a linear conductor 20, a first connection portion 21 connected to one end in the length direction of the linear conductor 20, and the other in the length direction of the linear conductor 20. A plurality of cooling devices 30 for cooling the linear conductor 20, provided so as to be separated from each other between the second connection portion 22 connected to the end, and the first connection portion 21 and the second connection portion 22; A plurality of cold insulation chambers 40 are provided between a pair of adjacent cooling devices 30 to keep the linear conductor 20 cold. In the present embodiment, as the linear conductor 20, a linear conductor 20a (see FIG. 2) whose conductor is exposed on the side surface and a linear conductor 20b (see FIG. 7) whose conductor is not exposed on the side surface are illustrated.
　線状導体２０ａは、図２に示すように、互いに並行に延びるように設けられた複数本（例えば、７本）の金属電線１０を撚り合わせた撚り線である。 As shown in FIG. 2, the linear conductor 20a is a stranded wire in which a plurality of (for example, seven) metal wires 10 provided so as to extend in parallel with each other are twisted together.
　金属電線１０は、図２に示すように、横断面が円形に形成され、例えば、銅、アルミニウム、銀などにより構成されている。ここで、金属電線１０の金属の純度は、９９．９９９質量％以上であり、好ましくは９９．９９９９質量％以上であり、より好ましくは、９９．９９９９８質量％以上である。また、金属電線１０の横断面における平均結晶粒径は、金属電線１０の直径の１／２０以上（例えば、１／１０程度、図３参照）であり、好ましくは、金属電線１０の直径の１／１０以上（例えば、１／５程度、図４参照）である。また、金属電線１０における鉄及びニッケルの総含有量は、１ｐｐｍ以下である。 As shown in FIG. 2, the metal wire 10 has a circular cross section and is made of, for example, copper, aluminum, silver, or the like. Here, the purity of the metal of the metal electric wire 10 is 99.999 mass% or more, preferably 99.9999 mass% or more, more preferably 99.99999 mass% or more. The average crystal grain size in the cross section of the metal wire 10 is 1/20 or more of the diameter of the metal wire 10 (for example, about 1/10, see FIG. 3). / 10 or more (for example, about 1/5, see FIG. 4). Moreover, the total content of iron and nickel in the metal wire 10 is 1 ppm or less.
　金属電線１０は、常温（２０℃）での電気抵抗Ｒ293K及び４．２Ｋでの電気抵抗Ｒ4.2Kの比率、すなわち、残留抵抗比（ＲＲＲ＝Ｒ293K／Ｒ4.2K）が５００以上、好ましくは５０００以上になっている。また、金属電線１０は、銅製の場合３８０Ｗ／（ｍ・Ｋ）程度、アルミニウム製の場合２００Ｗ／（ｍ・Ｋ）程度、銀製の場合４２０Ｗ／（ｍ・Ｋ）程度の高い熱伝導率（２０℃）を有している。ここで、熱伝導率は、ＪＩＳ Ｒ １６１１に基づいてレーザーフラッシュ法により測定される。 Metal wire 10, the electric resistance R 293 K and electric resistance R 4.2K ratio of at 4.2K at room temperature (20 ° C.), i.e., the residual resistance ratio (RRR = R 293K / R 4.2K ) is 500 or more, preferably Is over 5000. The metal electric wire 10 has a high thermal conductivity of about 380 W / (m · K) in the case of copper, about 200 W / (m · K) in the case of aluminum, and about 420 W / (m · K) in the case of silver (20 ° C). Here, the thermal conductivity is measured by a laser flash method based on JIS R 1611.
　一方、線状導体２０ｂは、図７に示すように、互いに並行に延びるように設けられた複数本（例えば、７本）の絶縁電線１５を撚り合わせた撚り線である。 On the other hand, as shown in FIG. 7, the linear conductor 20b is a stranded wire obtained by twisting a plurality of (for example, seven) insulated wires 15 provided so as to extend in parallel to each other.
　絶縁電線１５は、図７に示すように、金属電線１０と、金属電線１０の側面を被覆するように設けられたポリイミド樹脂製の絶縁層１１とを備えている。 As shown in FIG. 7, the insulated wire 15 includes a metal wire 10 and a polyimide resin insulating layer 11 provided so as to cover the side surface of the metal wire 10.
　絶縁層１１は、例えば、ブロック共重合ポリイミドにより構成されている、ここで、このブロック共重合ポリイミドは、例えば、ポリイミドの主鎖中にシロキサン結合を有し、分子中にアニオン性基を有している。また、このブロック共重合ポリイミドは、例えば、重量平均分子量が４５０００～９００００であり、数平均分子量が２００００～４００００である。なお、絶縁層１１の膜厚は、例えば、１μｍ～５０μｍ程度である。 The insulating layer 11 is made of, for example, a block copolymerized polyimide. Here, the block copolymerized polyimide has, for example, a siloxane bond in the main chain of the polyimide and an anionic group in the molecule. ing. The block copolymerized polyimide has, for example, a weight average molecular weight of 45,000 to 90,000 and a number average molecular weight of 20,000 to 40,000. Note that the film thickness of the insulating layer 11 is, for example, about 1 μm to 50 μm.
　第１接続部２１及び第２接続部２２は、例えば、銅製の接続端子であり、線状導体２０と圧着又は圧縮などにより固定されている。 The first connection portion 21 and the second connection portion 22 are, for example, copper connection terminals, and are fixed to the linear conductor 20 by crimping or compression.
　冷却装置３０は、図１に示すように、線状導体２０の一部を囲むように設けられた冷却室３１と、冷却室３１の後述する円筒体の側面に接続された冷媒供給部３２とを備えている。 As shown in FIG. 1, the cooling device 30 includes a cooling chamber 31 provided so as to surround a part of the linear conductor 20, and a refrigerant supply unit 32 connected to a side surface of a cylindrical body described later of the cooling chamber 31. It has.
　冷却室３１は、例えば、線状導体２０の周囲に設けられた円筒体と、その円筒体の一対の開口部にそれぞれ設けられ、線状導体２０が挿入された一対の環状体とを備え、ほぼ閉じた空間を形成している。ここで、冷却室３１は、例えば、真空断熱層が壁間に形成されたステンレス製の２重壁などの構造を有している。 The cooling chamber 31 includes, for example, a cylindrical body provided around the linear conductor 20, and a pair of annular bodies that are respectively provided in a pair of openings of the cylindrical body and into which the linear conductor 20 is inserted. An almost closed space is formed. Here, the cooling chamber 31 has a structure such as a double wall made of stainless steel in which a vacuum heat insulating layer is formed between the walls.
　冷媒供給部３２は、例えば、液体ヘリウムや液体窒素などの冷媒Ｃを冷却室３１の内部に供給するように設けられている。 The refrigerant supply unit 32 is provided so as to supply, for example, a refrigerant C such as liquid helium or liquid nitrogen into the cooling chamber 31.
　なお、本実施形態では、線状導体２０に液体の冷媒Ｃを接触させて線状導体２０を冷却する冷却装置３０を例示したが、線状導体２０を冷却する冷却装置は、蒸気や冷媒などの圧縮を利用した冷却機であってもよい。 In the present embodiment, the cooling device 30 that cools the linear conductor 20 by bringing the liquid refrigerant C into contact with the linear conductor 20 is exemplified, but the cooling device that cools the linear conductor 20 includes steam, refrigerant, and the like. A cooler using the compression of
　保冷室４０は、図１に示すように、隣り合う一対の冷却装置３０を連結すると共に、線状導体２０の一部を囲むように円筒状に設けられている。ここで、保冷室４０は、例えば、真空断熱層が管間に形成されたステンレス製の２重管などにより構成されている。 As shown in FIG. 1, the cold insulation chamber 40 connects a pair of adjacent cooling devices 30 and is provided in a cylindrical shape so as to surround a part of the linear conductor 20. Here, the cold insulation chamber 40 is composed of, for example, a stainless steel double tube in which a vacuum heat insulating layer is formed between the tubes.
　上記構成の冷却システム５０ａは、図１に示すように、各冷却装置３０の冷却室３１の内部に配置する線状導体２０を冷媒Ｃで冷却すると共に、冷却室３１に隣り合う保冷室４０の内部に冷却室３１からの冷媒Ｃが流れ込むことにより、保冷室４０の内部において線状導体２０を保冷するだけでなく冷却もするように構成されている。 As shown in FIG. 1, the cooling system 50 a configured as described above cools the linear conductors 20 arranged inside the cooling chambers 31 of the respective cooling devices 30 with the refrigerant C, and the cooling chambers 40 adjacent to the cooling chambers 31. The refrigerant C from the cooling chamber 31 flows into the interior, so that the linear conductor 20 is not only kept cool but also cooled inside the cold storage chamber 40.
　次に、本実施形態の冷却システム５０ａを構成する線状導体２０ａの製造方法について説明する。なお、本実施形態の製造方法は、準備工程、熱処理工程及び成形工程を備える。 Next, the manufacturing method of the linear conductor 20a which comprises the cooling system 50a of this embodiment is demonstrated. In addition, the manufacturing method of this embodiment includes a preparation process, a heat treatment process, and a molding process.
　＜準備工程＞
　図５に示すように、例えば、電気銅を鋳造することにより純度９９．９９９質量％以上のビレットを作製した後に、その作製されたビレットを複数のステップで伸線することにより、例えば、直径０．１ｍｍ～３．２ｍｍ程度の銅電線を作製する。 <Preparation process>
As shown in FIG. 5, for example, a billet having a purity of 99.999% by mass or more is produced by casting electrolytic copper, and then the produced billet is drawn in a plurality of steps. Make a copper wire of about 1mm to 3.2mm.
　＜熱処理工程＞
　上記準備工程で作製され、ボビンに巻き取った銅電線をバッチ焼き鈍し炉の内部に搬入した後に、炉内の銅電線を３００℃以上で1時間以上（好ましくは５００℃以上で１時間以上）の条件で水素などの還元雰囲気、窒素などの不活性ガス雰囲気又は真空雰囲気で熱処理することにより、銅電線の横断面における平均結晶粒径を銅電線の直径の１／２０以上、好ましくは１／１０以上にする。 <Heat treatment process>
After the copper electric wire produced in the above preparation process and batch-annealed on a bobbin and carried into the furnace, the copper electric wire in the furnace is at 300 ° C or higher for 1 hour or longer (preferably 500 ° C or higher for 1 hour or longer). Heat treatment in a reducing atmosphere such as hydrogen, an inert gas atmosphere such as nitrogen, or a vacuum atmosphere under certain conditions allows the average crystal grain size in the cross section of the copper wire to be 1/20 or more, preferably 1/10 of the diameter of the copper wire. That's it.
　なお、本実施形態では、銅電線を一括して熱処理するバッチ処理を行う製造方法を例示したが、例えば、上記準備工程で作製された銅電線をそのまま筒状のパイプ焼き鈍し炉の内部に搬入及び搬送させることにより、炉内で銅電線を搬送しながら５００℃以上で３０秒以上（好ましくは６００℃以上で３０秒以上）の条件で水素などの還元雰囲気、又は窒素などの不活性ガス雰囲気で連続して熱処理してもよい。 In addition, in this embodiment, although the manufacturing method which performs the batch process which heat-processes a copper electric wire collectively was illustrated, for example, the copper electric wire produced at the said preparatory process is carried into a cylindrical pipe annealing furnace as it is, and By carrying the copper wire in the furnace, it is carried out in a reducing atmosphere such as hydrogen or an inert gas atmosphere such as nitrogen under conditions of 500 ° C. or higher and 30 seconds or longer (preferably 600 ° C. or higher and 30 seconds or longer). You may heat-process continuously.
　＜成形工程＞
　上記熱処理工程で熱処理された銅電線を複数本準備し、それらの複数本の銅電線を撚り合わせることにより、撚り線（線状導体２０ａ）を作製する。 <Molding process>
A plurality of copper wires heat-treated in the heat treatment step are prepared, and the plurality of copper wires are twisted together to produce a stranded wire (linear conductor 20a).
　以上のようにして、本実施形態の線状導体２０ａを製造することができる。 As described above, the linear conductor 20a of this embodiment can be manufactured.
　なお、本実施形態では、熱処理工程を行った後に、成形工程を行う製造方法を例示したが、図６に示すように、上述した準備工程を行った後に、上述した成形工程を行い、最後に、上述した熱処理工程を行ってもよい。また、本実施形態の線状導体２０ｂは、上述した線状導体２０ａの製造方法と同様に、図８に示すように、上述した準備工程及び熱処理工程を行った後に、その熱処理された銅電線の側面に対する電着塗装又はディップ塗装とその後の焼き付け処理とを行うことにより、絶縁層１１を形成し、最後に、上述した成形工程を行うことにより、製造することができる。 In addition, in this embodiment, although the manufacturing method which performs a shaping | molding process after performing a heat treatment process was illustrated, after performing the preparation process mentioned above, as shown in FIG. The above-described heat treatment step may be performed. Moreover, the linear conductor 20b of this embodiment is the heat-treated copper electric wire, after performing the preparation process and heat treatment process which were mentioned above, as shown in FIG. 8, similarly to the manufacturing method of the line conductor 20a mentioned above. The insulating layer 11 is formed by performing electrodeposition coating or dip coating on the side surface of the film and subsequent baking treatment, and finally, the molding process described above can be performed.
　次に、具体的に行った実験について説明する。 Next, a specific experiment will be described.
　具体的には、下記の表１に示すように、実施例１～９として、純度９９．９９９質量％、９９．９９９９質量％又は９９．９９９９８質量％の銅線材を用い、上述した線状導体２０ａの製造方法と同様に、所定の条件の熱処理を行うことにより、直径０．３２ｍｍの単線の銅電線を作製した。また、比較例１及び２として、純度９９．９９質量％及び９９．９９９質量％の銅線材を用い、所定の条件の熱処理を行うことにより、直径０．３２ｍｍの単線の銅電線を作製した。そして、それらの作製された各銅電線について、結晶粒径、ＲＲＲ、並びに鉄及びニッケルの総含有量を評価した。ここで、結晶粒径、すなわち、平均結晶粒径については、銅電線の横断面のミクロ組織から｛√（結晶の平均面積／π）｝×２の式に基づいて算出した。また、ＲＲＲについては、室温（２０℃＝２９３Ｋ）における電気抵抗Ｒ293K、及び液体ヘリウム温度（４．２Ｋ）における電気抵抗Ｒ4.2Kを四端子法により測定して、Ｒ293K／Ｒ4.2Kの式より算出した。また、鉄及びニッケルの総含有量については、サーモフィッシャーサイエンティフィック株式会社製のＶＧ９０００を用いて、グロー放電質量分析法により測定した。また、銅の純度は、同じくグロー放電質量分析法により、銅の含有量、又は不純物（銀、アルミニウム、ヒ素、ビスマス、クロム、鉄、マグネシウム、ナトリウム、ニッケル、硫黄、アンチモン、ケイ素などの元素）の含有量を測定することにより、算出した。 Specifically, as shown in Table 1 below, as Examples 1 to 9, a copper wire having a purity of 99.999 mass%, 99.9999 mass%, or 99.999998 mass% was used, and the above-described linear conductor was used. Similarly to the manufacturing method 20a, a single-wire copper wire having a diameter of 0.32 mm was manufactured by performing heat treatment under predetermined conditions. Further, as Comparative Examples 1 and 2, a copper wire having a purity of 99.99% by mass and 99.999% by mass was used, and a single-wire copper wire having a diameter of 0.32 mm was produced by performing heat treatment under predetermined conditions. And about each produced copper electric wire, the crystal grain size, RRR, and the total content of iron and nickel were evaluated. Here, the crystal grain size, that is, the average crystal grain size was calculated based on the formula {√ (average crystal area / π)} × 2 from the microstructure of the cross section of the copper electric wire. Also, the RRR, room temperature electrical resistance R 293 K at (20 ℃ = 293K), and the electrical resistance R 4.2 K in liquid helium temperature (4.2 K) as measured by the four probe method, R 293 K / R 4.2 K of Calculated from the formula. The total content of iron and nickel was measured by glow discharge mass spectrometry using VG9000 manufactured by Thermo Fisher Scientific Co., Ltd. The purity of copper is also determined by glow discharge mass spectrometry. Copper content or impurities (elements such as silver, aluminum, arsenic, bismuth, chromium, iron, magnesium, sodium, nickel, sulfur, antimony, silicon) It was calculated by measuring the content of.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実験結果としては、比較例１では、９９．９９質量％の銅線材を５００℃で１時間（３６００秒）の条件で熱処理しても、ＲＲＲが４００程度になるものの、実施例１～３では、より高純度の９９．９９９質量％の銅線材を用い、３００℃以上で１時間以上の条件で熱処理することにより、ＲＲＲが１５００～４６００程度に高くなることが確認された。また、連続処理を行った実施例４では、５００℃で３０秒の条件で熱処理するだけでＲＲＲが２８００程度に高くなることが確認された。さらに、９９．９９９９質量％の銅線材を用いた実施例５では、５００℃で３０秒の条件で熱処理するだけでＲＲＲが４５００程度に高くなることが確認された。また、さらに高純度の９９．９９９９８質量％の銅線材を用いた実施例６では、５００℃で３０秒の条件で熱処理するだけでＲＲＲが５４００程度に高くなることが確認された。同じく９９．９９９９８質量％の銅線材を用いた実施例７～９では、３００℃以上で１時間以上の条件で熱処理することにより、ＲＲＲが４８００～９８００程度に高くなることが確認された。 As a result of the experiment, in Comparative Example 1, although 99.99 mass% copper wire was heat-treated at 500 ° C. for 1 hour (3600 seconds), the RRR was about 400, but in Examples 1 to 3, It was confirmed that the RRR was increased to about 1500 to 4600 when heat-treated at a temperature of 300 ° C. or higher for 1 hour or longer using a higher purity 99.999 mass% copper wire. Moreover, in Example 4 which performed the continuous process, it was confirmed that RRR will become high to about 2800 only by heat-processing on the conditions for 30 second at 500 degreeC. Furthermore, in Example 5 using a 99.9999 mass% copper wire, it was confirmed that the RRR increases to about 4500 just by heat treatment at 500 ° C. for 30 seconds. Further, in Example 6 using a 99.99998% by mass copper wire of higher purity, it was confirmed that the RRR was increased to about 5400 just by heat treatment at 500 ° C. for 30 seconds. Similarly, in Examples 7 to 9 using 99.99998% by mass of copper wire, it was confirmed that the RRR was increased to about 4800 to 9800 by heat treatment at 300 ° C. or more for 1 hour or more.
　また、平均結晶粒径については、比較例１及び２で、銅電線の直径の１／２２及び１／２１程度となるものの、実施例１～９では、銅電線の直径の１／１６～１／６程度となり、銅電線の直径の１／２０（好ましくは１／１０）以上になることが確認された。 The average crystal grain size is about 1/22 and 1/21 of the diameter of the copper wire in Comparative Examples 1 and 2, but in Examples 1 to 9, 1/16 to 1 of the diameter of the copper wire. It was about / 6, and it was confirmed that it became 1/20 (preferably 1/10) or more of the diameter of the copper electric wire.
　また、鉄及びニッケルの総含有量については、比較例１及び２で、１．１及び０．３ｐｐｍになるものの、実施例１～９では、０．０２ｐｐｍ～０．５ｐｐｍとなり、１ｐｐｍ以下になることが確認された。 The total content of iron and nickel is 1.1 and 0.3 ppm in Comparative Examples 1 and 2, but 0.02 to 0.5 ppm in Examples 1 to 9 and 1 ppm or less. It was confirmed.
　次に、具体的に行った他の実験について説明する。 Next, other experiments that were specifically performed will be described.
　実施例として、純度９９．９９９９質量％で直径１．０ｍｍの銅電線を用いて、上述した実施例９の熱処理を行った後に、その側面にポリイミド樹脂を電着塗装することにより、厚さ１０μｍ程度のポリイミド樹脂製の絶縁層を有する絶縁電線を作製した。また、比較例として、純度９９．９９９９質量％で直径１．０ｍｍの銅電線を用いて、上述した実施例９の熱処理を行った後に、その側面にエポキシ樹脂をディップ塗装することにより、厚さ１０μｍ程度のエポキシ樹脂製の絶縁層を有する絶縁電線を作製した。それらの作製された各絶縁電線を内径１ｍｍでコイル状に緊密に１０回巻き付けて試験体をそれぞれ作製し、それらの各試験体を液体窒素に１０分間浸漬した後に、常温（２０℃）に戻し、各試験体の絶縁層の表面を２０倍の拡大鏡で観察して、割れの有無を確認した。 As an example, using a copper wire having a purity of 99.9999% by mass and a diameter of 1.0 mm, the heat treatment of Example 9 described above was performed, and then a polyimide resin was electrodeposited on the side surface to obtain a thickness of 10 μm. An insulated wire having an insulating layer made of a polyimide resin was prepared. In addition, as a comparative example, after performing the heat treatment of Example 9 described above using a copper wire having a purity of 99.9999% by mass and a diameter of 1.0 mm, the epoxy resin is dip-coated on the side surface to obtain a thickness. An insulated wire having an insulating layer made of epoxy resin of about 10 μm was produced. Each of the manufactured insulated wires was tightly wound 10 times in a coil shape with an inner diameter of 1 mm to prepare test specimens, and each test specimen was immersed in liquid nitrogen for 10 minutes, and then returned to room temperature (20 ° C.). The surface of the insulating layer of each test specimen was observed with a 20x magnifier to check for cracks.
　実験結果としては、実施例では、絶縁層に割れが確認されなかったのに対し、比較例では、絶縁層に割れが確認された。 As an experimental result, cracks were not confirmed in the insulating layer in the example, whereas cracks were confirmed in the insulating layer in the comparative example.
　なお、上記各実施例では、金属電線として銅電線を例示したが、本発明は、アルミニウムや銀製などの金属電線にも適用することができる。 In each of the above embodiments, a copper wire is exemplified as the metal wire, but the present invention can also be applied to a metal wire made of aluminum or silver.
　以上説明したように、本実施形態の冷却システム５０ａによれば、純度９９．９９９質量％以上の各金属電線１０の横断面における平均結晶粒径が金属電線１０の直径の１／２０以上であるので、金属電線１０における結晶欠陥が減少して、金属電線１０のＲＲＲが５００以上に高くなる。ここで、このような低電気抵抗で高純度の金属電線１０を有する線状導体２０は、２００Ｗ／（ｍ・Ｋ）～４２０Ｗ／（ｍ・Ｋ）程度の高い熱伝導率（２０℃）を有しているので、例えば、４．２Ｋ程度の極低温でもニオブチタンなどの超伝導材料よりも高い熱伝導率を有することになる。そのため、線状導体２０の一部を極低温に冷却することにより、その極低温が線状導体２０全体に広がって、線状導体２０全体が極低温に冷却される。これにより、第１接続部２１及び第２接続部２２の間で線状導体２０を冷却する冷却装置３０を簡素化することができる。しかも、冷却システム５０ａを構成する線状導体２０は、例えば、製造及び加工が比較的に困難なニオブチタンなどの超伝導材料を用いることなく、製造及び加工が比較的に容易な金属電線１０を用いて構成されているので、可及的にコストが抑制された冷却システム５０ａを構築することができる。 As described above, according to the cooling system 50a of the present embodiment, the average crystal grain size in the cross section of each metal wire 10 having a purity of 99.999% by mass or more is 1/20 or more of the diameter of the metal wire 10. Therefore, crystal defects in the metal wire 10 are reduced, and the RRR of the metal wire 10 is increased to 500 or more. Here, the linear conductor 20 having such a low-electric resistance and high-purity metal wire 10 has a high thermal conductivity (20 ° C.) of about 200 W / (m · K) to 420 W / (m · K). Therefore, it has a higher thermal conductivity than a superconducting material such as niobium titanium even at an extremely low temperature of about 4.2K. Therefore, by cooling a part of the linear conductor 20 to the cryogenic temperature, the cryogenic temperature spreads over the entire linear conductor 20 and the entire linear conductor 20 is cooled to the cryogenic temperature. Thereby, the cooling device 30 which cools the linear conductor 20 between the 1st connection part 21 and the 2nd connection part 22 can be simplified. In addition, the linear conductor 20 constituting the cooling system 50a uses, for example, the metal electric wire 10 that is relatively easy to manufacture and process without using a superconductive material such as niobium titanium that is relatively difficult to manufacture and process. Therefore, it is possible to construct the cooling system 50a with the cost reduced as much as possible.
　また、本実施形態の冷却システム５０ａによれば、互いに離間する複数の冷却装置３０の間に線状導体２０の一部を囲む保冷室４０が設けられているので、各冷却装置３０で極低温に冷却された線状導体２０の部分の極低温が保冷室４０の内部に配置する線状導体２０の部分に比較的高い熱伝導率を有する線状導体２０を介して広がることにより、線状導体２０全体が極低温に冷却され、線状導体を全長にわたって冷却装置で冷却する場合よりも、冷却装置３０をコンパクトにすることができると共に、冷却に関するランニングコストを抑制することができる。 Further, according to the cooling system 50a of the present embodiment, the cold insulation chamber 40 that surrounds a part of the linear conductor 20 is provided between the plurality of cooling devices 30 that are separated from each other. The cryogenic temperature of the portion of the linear conductor 20 that has been cooled to spreads through the linear conductor 20 having a relatively high thermal conductivity to the portion of the linear conductor 20 that is disposed inside the cold insulation chamber 40, thereby forming a linear shape. The entire conductor 20 is cooled to a very low temperature, and the cooling device 30 can be made more compact than the case where the linear conductor is cooled by the cooling device over the entire length, and the running cost related to cooling can be suppressed.
　また、本実施形態の冷却システム５０ａによれば、冷却装置３０では、それに隣り合う保冷室４０に冷却装置３０からの冷媒Ｃが流れ込むようになっているので、保冷室４０の内部において、冷却装置３０からの冷媒Ｃを用いて線状導体２０が冷却されることになり、冷却装置３０から漏れ出た冷媒Ｃを有効利用することができる。 Further, according to the cooling system 50a of the present embodiment, in the cooling device 30, the refrigerant C from the cooling device 30 flows into the cold insulating chamber 40 adjacent to the cooling device 30, so that the cooling device is provided inside the cold insulating chamber 40. The linear conductor 20 is cooled by using the refrigerant C from the refrigerant 30, and the refrigerant C leaked from the cooling device 30 can be used effectively.
　また、本実施形態の冷却システム５０ａによれば、複数の金属電線１０が互いに並行に延びるように設けられた撚り線により線状導体２０が構成されているので、単線の金属電線を用いた場合よりも線状導体２０の強度を高くすることができる。 Moreover, according to the cooling system 50a of this embodiment, since the linear conductor 20 is comprised by the strand wire provided so that the several metal electric wire 10 might mutually extend in parallel, when a single wire metal electric wire is used As a result, the strength of the linear conductor 20 can be increased.
　また、本実施形態の冷却システム５０ａによれば、金属電線１０における鉄及びニッケルの総含有量が１ｐｐｍ以下であるので、例えば、磁気共鳴画像診断装置や核磁気共鳴診断装置などの磁束密度１Ｔ以上の強磁場で好適に使用することができる。 Moreover, according to the cooling system 50a of this embodiment, since the total content of iron and nickel in the metal wire 10 is 1 ppm or less, the magnetic flux density of 1 T or more, such as a magnetic resonance imaging diagnostic apparatus or a nuclear magnetic resonance diagnostic apparatus, is used. It can be suitably used in a strong magnetic field.
　また、本実施形態の冷却システム５０ａによれば、線状導体２０を構成する金属電線１０が高純度の銅電線である場合には、導体が超伝導材料でなく、接続技術が確立された銅電線であるので、周辺機器との接続を容易に行うことができる。 In addition, according to the cooling system 50a of the present embodiment, when the metal electric wire 10 constituting the linear conductor 20 is a high-purity copper electric wire, the conductor is not a superconducting material, and the connection technology is established. Since it is an electric wire, it can be easily connected to a peripheral device.
　また、本実施形態の線状導体２０ｂを用いた冷却システム５０ａによれば、金属電線１０がポリイミド樹脂製の絶縁層１１で被覆されているので、絶縁層１１の柔軟性により、極低温環境（液体窒素温度：－１９６℃）であっても、金属電線１０を被覆する絶縁層１１の割れによる破壊を抑制することができる。また、金属電線１０と絶縁層１１とでは、それらの材質を考慮すると、熱膨張係数が必然的に大きく異なってしまう。しかしながら、線状導体２０ｂの環境温度に起因して金属電線１０が伸縮（膨張／収縮）しても、絶縁層１１がその柔軟性により金属電線１０の側面に密着したまま金属電線１０の伸縮に追従するので、常温環境と極低温環境とを繰り返すような過酷な条件下であっても、絶縁層１１の劣化を抑制することができる。 Moreover, according to the cooling system 50a using the linear conductor 20b of this embodiment, since the metal electric wire 10 is covered with the insulating layer 11 made of polyimide resin, the flexibility of the insulating layer 11 allows a cryogenic environment ( Even at a liquid nitrogen temperature of −196 ° C., breakage due to cracking of the insulating layer 11 covering the metal wire 10 can be suppressed. In addition, when considering the materials of the metal wire 10 and the insulating layer 11, the thermal expansion coefficients are inevitably greatly different. However, even if the metal wire 10 expands / contracts (expands / shrinks) due to the environmental temperature of the linear conductor 20b, the insulating layer 11 can be expanded and contracted while being in close contact with the side surface of the metal wire 10 due to its flexibility. Since it follows, the deterioration of the insulating layer 11 can be suppressed even under harsh conditions in which the normal temperature environment and the cryogenic environment are repeated.
　《発明の実施形態２》
　図９は、本実施形態の冷却システム５０ｂを示す断面図である。なお、以下の実施形態において、図１～図８と同じ部分については同じ符号を付して、その詳細な説明を省略する。 << Embodiment 2 of the Invention >>
FIG. 9 is a cross-sectional view showing the cooling system 50b of the present embodiment. In the following embodiments, the same portions as those in FIGS. 1 to 8 are denoted by the same reference numerals, and detailed description thereof is omitted.
　上記実施形態１では、複数の冷却装置３０を備えた冷却システム５０ａを例示したが、本実施形態では、１つの冷却装置３５を備えた冷却システム５０ｂを例示する。 In the first embodiment, the cooling system 50a including the plurality of cooling devices 30 is illustrated, but in the present embodiment, the cooling system 50b including one cooling device 35 is illustrated.
　冷却システム５０ｂは、図９に示すように、上記実施形態１の線状導体２０ａ又は２０ｂからなる線状導体２０と、線状導体２０の長さ方向の一方端に接続された第１接続部２１と、線状導体２０の長さ方向の他方端に接続された第２接続部２２と、第１接続部２１及び第２接続部２２の間に設けられ、線状導体２０を冷却するための冷却装置３５とを備えている。 As shown in FIG. 9, the cooling system 50 b includes a linear conductor 20 composed of the linear conductor 20 a or 20 b of the first embodiment, and a first connection portion connected to one end in the length direction of the linear conductor 20. 21, provided between the second connection part 22 connected to the other end in the length direction of the linear conductor 20, and the first connection part 21 and the second connection part 22, for cooling the linear conductor 20. The cooling device 35 is provided.
　冷却装置３５は、図９に示すように、線状導体２０の全体を囲むように設けられた冷却室３３と、冷却室３３の後述する円筒体の側面に接続された冷媒供給部３４とを備えている。 As shown in FIG. 9, the cooling device 35 includes a cooling chamber 33 provided so as to surround the entire linear conductor 20, and a refrigerant supply unit 34 connected to a side surface of a cylindrical body described later of the cooling chamber 33. I have.
　冷却室３３は、例えば、線状導体２０の周囲に設けられた円筒体と、その円筒体の一対の開口部にそれぞれ設けられ、線状導体２０が挿入された一対の環状体とを備え、ほぼ閉じた空間を形成している。ここで、冷却室３３は、例えば、真空断熱層が壁間に形成されたステンレス製の２重壁などの構造を有している。 The cooling chamber 33 includes, for example, a cylindrical body provided around the linear conductor 20 and a pair of annular bodies that are provided in a pair of openings of the cylindrical body and into which the linear conductor 20 is inserted, An almost closed space is formed. Here, the cooling chamber 33 has a structure such as a double wall made of stainless steel in which a vacuum heat insulating layer is formed between the walls.
　冷媒供給部３４は、例えば、液体ヘリウムなどの冷媒Ｃを冷却室３３の内部に供給するように設けられている。 The refrigerant supply unit 34 is provided so as to supply, for example, a refrigerant C such as liquid helium into the cooling chamber 33.
　上記構成の冷却システム５０ｂは、図９に示すように、冷却装置３５の冷却室３１の内部に配置する線状導体２０を冷媒Ｃで冷却するように構成されている。 The cooling system 50b having the above-described configuration is configured to cool the linear conductor 20 disposed inside the cooling chamber 31 of the cooling device 35 with the refrigerant C as shown in FIG.
　以上説明したように、本実施形態の冷却システム５０ｂによれば、上記実施形態１と同様に、横断面が円形に形成され純度９９．９９９質量％以上の金属電線１０を複数有し、各金属電線１０の横断面における平均結晶粒径が金属電線１０の直径の１／２０以上に形成された線状導体２０を第１接続部２１及び第２接続部２２の間で冷却するように構成されているので、可及的にコストが抑制された冷却システム５０ｂを構築することができる。 As described above, according to the cooling system 50b of the present embodiment, similarly to the first embodiment, each of the metal wires 10 includes a plurality of metal wires 10 having a circular cross section and a purity of 99.999% by mass or more. The linear conductor 20 formed so that the average crystal grain size in the cross section of the electric wire 10 is 1/20 or more of the diameter of the metal electric wire 10 is cooled between the first connecting portion 21 and the second connecting portion 22. Therefore, it is possible to construct the cooling system 50b whose cost is suppressed as much as possible.
　また、本実施形態の冷却システム５０ｂによれば、第１接続部２１及び第２接続部２２の間では、線状導体２０の全長にわたるように１つの冷却装置３５が設けられているので、超伝導材料を用いた線状導体を冷却する場合よりも、線状導体２０を内部に備え、線状導体２０を冷却可能に構成されたケーブルの直径が小さくなり、冷却装置３５をコンパクトにすることができる。 Further, according to the cooling system 50b of the present embodiment, the single cooling device 35 is provided between the first connection portion 21 and the second connection portion 22 so as to extend over the entire length of the linear conductor 20, so Rather than cooling a linear conductor using a conductive material, the diameter of the cable configured to be equipped with the linear conductor 20 and capable of cooling the linear conductor 20 is reduced, and the cooling device 35 is made compact. Can do.
　なお、上記各実施形態では、７本の単線からなる撚り線の線状導体を備えた冷却システムを例示したが、本発明は、７本以外の単線からなる撚り線や１本の単線の線状導体を備えた冷却システム、及び互いに並行に延びるように複数の線状導体が設けられた冷却システムにも適用することができる。 In each of the above embodiments, the cooling system provided with a stranded wire conductor composed of seven single wires has been exemplified. However, the present invention is not limited to a single wire other than seven stranded wires or one single wire. The present invention can also be applied to a cooling system including a linear conductor and a cooling system provided with a plurality of linear conductors extending in parallel with each other.
　また、上記各実施形態では、横断面が円形に形成された丸線の線状導体を備えた冷却システムを例示したが、本発明は、横断面が扁平した円形に形成された線状導体、横断面が矩形状に形成された平角線の線状導体、又は管状導体などを備えた冷却システムにも適用することができる。 In each of the above embodiments, a cooling system including a round wire conductor having a circular cross section is exemplified, but the present invention is a linear conductor formed in a circle having a flat cross section, The present invention can also be applied to a cooling system including a flat wire conductor having a rectangular cross section or a tubular conductor.
　以上説明したように、本発明は、可及的にコストが抑制された冷却システムを構築することができるので、低電気抵抗が要望される（電力）ケーブルについて有用である。 As described above, the present invention can construct a cooling system in which the cost is suppressed as much as possible. Therefore, the present invention is useful for a (electric power) cable that requires low electrical resistance.
１０　　金属電線
１１　　絶縁層
２０，２０ａ，２０ｂ　　線状導体（撚り線）
２１　　第１接続部
２２　　第２接続部
３０，３５　　冷却装置
３１，３３　　冷却室
３２，３４　　冷媒供給部
４０　　保冷室
５０ａ，５０ｂ　　冷却システム DESCRIPTION OF SYMBOLS 10 Metal electric wire 11 Insulating layer 20, 20a, 20b Linear conductor (stranded wire)
21 1st connection part 22 2nd connection part 30, 35 Cooling device 31, 33 Cooling chamber 32, 34 Refrigerant supply part 40 Cold storage room 50a, 50b Cooling system

Claims (10)

  1. 　横断面が円形に形成され、純度９９．９９９質量％以上の金属電線を有し、該金属電線の横断面における平均結晶粒径が該金属電線の直径の１／２０以上に形成された線状導体と、
    　上記線状導体の一方端に接続された第１接続部と、
    　上記線状導体の他方端に接続された第２接続部と、
    　上記第１接続部及び第２接続部の間に設けられ、上記線状導体を冷却する冷却装置とを備えている、冷却システム。     A wire having a cross section formed in a circle and having a metal wire with a purity of 99.999% by mass or more, and having an average crystal grain size in the cross section of the metal wire of 1/20 or more of the diameter of the metal wire Conductors,
    A first connecting portion connected to one end of the linear conductor;
    A second connection portion connected to the other end of the linear conductor;
    A cooling system comprising: a cooling device that is provided between the first connection portion and the second connection portion and cools the linear conductor.
  2. 　上記第１接続部及び第２接続部の間には、上記冷却装置が上記線状導体に沿って互いに離間するように複数設けられ、
    　上記複数の冷却装置の間には、上記線状導体を囲むように保冷室が設けられている、請求項１に記載された冷却システム。     A plurality of the cooling devices are provided between the first connection part and the second connection part so as to be separated from each other along the linear conductor,
    The cooling system according to claim 1, wherein a cooling chamber is provided between the plurality of cooling devices so as to surround the linear conductor.
  3. 　上記冷却装置は、冷媒を介して上記線状導体を冷却し、該冷却装置に隣り合う上記保冷室に該冷却装置からの冷媒が流れ込むように設けられている、請求項２に記載された冷却システム。 The cooling device according to claim 2, wherein the cooling device is provided such that the linear conductor is cooled via a refrigerant, and the refrigerant from the cooling device flows into the cold insulation chamber adjacent to the cooling device. system.
  4. 　上記第１接続部及び第２接続部の間には、上記冷却装置が上記線状導体の全長にわたるように１つ設けられている、請求項１に記載された冷却システム。 The cooling system according to claim 1, wherein one cooling device is provided between the first connection portion and the second connection portion so as to extend over the entire length of the linear conductor.
  5. 　上記冷却装置は、上記線状導体を囲むように設けられた冷却室と、該冷却室の内部に冷媒を供給する冷媒供給部とを備えている、請求項１乃至４の何れか１つに記載された冷却システム。 5. The cooling device according to claim 1, comprising: a cooling chamber provided so as to surround the linear conductor; and a refrigerant supply unit that supplies a refrigerant to the inside of the cooling chamber. The cooling system described.
  6. 　上記線状導体は、上記金属電線を複数有し、該複数の金属電線が互いに並行に延びるように設けられた撚り線である、請求項１乃至５の何れか１つに記載された冷却システム。 The cooling system according to any one of claims 1 to 5, wherein the linear conductor is a stranded wire having a plurality of the metal electric wires and the plurality of metal electric wires extending in parallel with each other. .
  7. 　上記金属電線の純度は、９９．９９９９質量％以上である、請求項１乃至６の何れか１つに記載された冷却システム。 The cooling system according to any one of claims 1 to 6, wherein the purity of the metal electric wire is 99.9999% by mass or more.
  8. 　上記金属電線の横断面における平均結晶粒径は、上記金属電線の直径の１／１０以上である、請求項１乃至７の何れか１つに記載された冷却システム。 The cooling system according to any one of claims 1 to 7, wherein an average crystal grain size in a cross section of the metal electric wire is 1/10 or more of a diameter of the metal electric wire.
  9. 　上記金属電線における鉄及びニッケルの総含有量は、１ｐｐｍ以下である、請求項１乃至８の何れか１つに記載された冷却システム。 The cooling system according to any one of claims 1 to 8, wherein a total content of iron and nickel in the metal electric wire is 1 ppm or less.
  10. 　上記金属電線は、ポリイミド樹脂製の絶縁層で被覆されている、請求項１乃至９の何れか１つに記載された冷却システム。 The cooling system according to any one of claims 1 to 9, wherein the metal electric wire is covered with an insulating layer made of polyimide resin.
PCT/JP2014/001445 2013-03-27 2014-03-13 Cooling system WO2014156027A1 (en)

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JPS6461006A (en) * 1987-09-01 1989-03-08 Toshiba Corp Superconducting device
JPH04259359A (en) * 1991-02-14 1992-09-14 Dowa Mining Co Ltd Manufacture of high purity copper wire constituted of coarse crystalline grain
JP2001229750A (en) * 2000-02-21 2001-08-24 Toshiba Corp Superconducting cable
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