JPH0917627A - Bobbin for superconducting coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain generation of quench by constituting a bobbin of fiber reinforced plastic which contains polyethylene fiber exhibiting a negative thermal expansion coefficient and reinforced material whose modulus of elasticity is larger than that of the polyethylene fiber, and orientating the polyethylene fibers in a specific angle range, with respect to the shaft axis line of the bobbin. SOLUTION: This bobbin for a superconducting coil is constituted of matrix resin, polyethylene fiber exhibiting a negative thermal expansion coefficient in the fiber direction, and reinforced material whose modulus of elasticity is larger than that of the polyethylene fiber. The polyethylene fiber is orientated in the range of ±35-90 degrees with respect to the shaft axis line of the bobbin, and has characteristics that the strength is at least 1.32GPa and the modulus of elasticity is at least 23.9GPa. The reinforced material is alumina fiber and has characteristics that the strength is at least 1200Mpa, and the modulus of elasticity is at least 120GPa.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a bobbin for a superconducting coil.

[0002]

2. Description of the Related Art Structural classification of superconducting coil devices is roughly classified into several types. Those with reels can also be classified as one type. Many of these types of superconducting coil devices are for large currents, such as those in which a superconducting coil is formed by directly winding a superconductor around the outer periphery of a winding frame,
A superconductor is wound around the outer circumference of the winding frame to form a coil element of the innermost layer, and coil elements are sequentially formed on the outer side of the coil element of the innermost layer through a spacer to form a superconducting coil having a multi-layer structure. Something that has been done is known. In addition, for alternating current or pulse use, a glass fiber reinforced plastic (hereinafter abbreviated as GFRP) having an epoxy resin matrix as the winding frame is used to prevent generation of eddy currents in the winding frame. ing.

Such a superconducting coil device is used while being immersed in a cryogenic liquid typified by liquid helium in order to keep the superconductor forming the superconducting coil at a temperature below the superconducting transition temperature. To be done.

However, the conventional superconducting coil device having the winding frame made of GFRP has the following problems.

That is, as shown in FIG. 3 (a), GFR
The superconducting coil 2 is formed by winding the superconducting wire 2 around the winding frame 1 made of P.
When the superconducting coil device 4 formed by forming is formed in a cryogenic liquid, the glass fiber and the epoxy resin forming the reel 1 have a positive coefficient of thermal expansion. It contracts in the axial direction as well as in the radial direction as indicated by thick arrows A and B.

On the other hand, the superconductor 2 forming the superconducting coil 3 is also made of a metal material having a positive coefficient of thermal expansion. Therefore, the superconducting coil 3 is indicated by the thick arrow C in FIG.
And D, it contracts axially as well as radially.

As described above, when the superconducting coil device 4 is simply immersed in the cryogenic liquid, the reel 1 and the superconducting coil 3 are heat-contracted into the same form, so that the loosened state is caused in the connection between the two. There is no such thing.

However, when a current is passed through the superconducting coil 3 while it is being cooled to an extremely low temperature, the electromagnetic force of this current causes the superconducting coil 3 to be indicated by thick arrows C'and E in FIG. 3 (b). Thus, the amount of contraction in the axial direction further increases, and the expansion in the radial direction reversely occurs. Therefore, looseness occurs in the fixed state of the superconducting coil 3 with respect to the winding frame 1.

When the loosening occurs, the whole or a part of the superconducting coil 3 becomes easy to move while energized. Even if it moves a little, frictional heat is generated. Since the cryogenic liquid typified by liquid helium has a very small specific heat,
It becomes difficult to quickly absorb frictional heat with a cryogenic liquid, and as a result, there is a problem that the superconductor 2 undergoes normal conduction transition (quenching).

Therefore, in order to solve this problem, recently, a reel is formed of a plastic (hereinafter abbreviated as DFRP) reinforced with high strength polyethylene fibers (hereinafter abbreviated as DF). Being tried.

Unlike ordinary glass fibers and ceramic fibers, DF has a peculiar property that it expands in the fiber direction at low temperatures. That is, this D
The DFRP-based molded product reinforced by F exhibits a negative coefficient of thermal expansion in the fiber direction, as indicated by a single circle in FIG.

The roving strands of this DF are wound around a mandrel which is rotating while containing an epoxy resin serving as a matrix, for example, by a spiral winding method.
When the tubular DFRP molded body 5 as shown in (a) is formed, the dimensional changes of the DFRP molded body 5 due to the temperature in the circumferential direction and the axial direction are as shown in FIG. 5 (b). Winding angle θ of the roving strand with respect to the axis of
Depends on

Here, in the spiral winding method, | θ | is in the range of 0 ° to 90 °, and it is measured from the axis of the mandrel to the roving strand in the clockwise direction or in the counterclockwise direction. The sign of θ becomes plus or minus depending on whether it is done or not.

In the spiral winding method, a roving strand is spirally wound from end to end of a rotating mandrel, for example, at a winding angle θ = + 75 °, and then in the opposite direction at a winding angle θ = −75 °. Then, in this way, it is repeatedly wound several times. Such a winding method is usually called “± 75 ° winding” or “winding at a winding angle θ of ± 75 °”.

FIG. 6 shows the relationship between the dimensional change (thermal expansion coefficient) with temperature and the winding angle θ. These data are obtained from a plurality of molded products formed by winding roving strands into a tubular shape as shown in FIG. 5 (a) by the spiral winding method shown in FIG. 5 (b). is there.

In the figure, Xa represents the coefficient of thermal expansion of the DFRP molded body in the axial direction, and Xc represents the coefficient of thermal expansion of the DFRP molded body in the circumferential direction. In addition, in this FIG.
The thermal expansion coefficient of the P type molded body in the axial direction is Za, and it is also GF
The coefficient of thermal expansion in the circumferential direction of the RP-based molded product is indicated by Zc, and the axial direction of the ADFRP-based molded product (AF: DF is mixed at a ratio of 50:50; ADFRP and AF will be defined later). The coefficient of thermal expansion of is indicated by Ya, and the coefficient of thermal expansion of the ADFRP-based molded article in the circumferential direction is indicated by Yc.

As can be seen from FIG. 6, in the case of the DFRP type molded body, even if the matrix used has a positive coefficient of thermal expansion, the winding angle θ is about 40 to 90 degrees due to the characteristics of DF. In the range, the coefficient of thermal expansion in the circumferential direction changes from a small positive value to a large negative value, and conversely, the coefficient of thermal expansion in the axial direction changes from a small negative value to a large positive value. Therefore, in the DFRP-based molded body in which the winding angle θ is set in the above range,
Greatly expands (expands) in the circumferential direction as the temperature decreases
However, it will contract greatly in the axial direction.

On the other hand, in the case of the GFRP type molded body, since GF itself has a positive coefficient of thermal expansion in any direction, no matter what value the winding angle θ is set to, The coefficients of thermal expansion in the circumferential direction and the axial direction are positive, and the characteristics of the DFRP-based molded product cannot be obtained.

By making use of the above-mentioned characteristics of the DFRP-based molded product and forming a reel with this DFRP-based molded product, ideal characteristics for preventing quenching can be exhibited in the reel.

That is, as shown in FIG. 7 (a), a superconducting coil device 14 in which a superconducting coil 12 is wound around a DFRP winding frame 11 in which the winding angle θ is set in the above range to form a superconducting coil 13. When is immersed in a cryogenic liquid, the reel 11 contracts in the axial direction and expands in the circumferential direction as indicated by thick arrows J and K in the figure. On the other hand, the superconducting coil 13 contracts in the axial direction and in the circumferential direction, as indicated by thick arrows C and D in the figure.

Thus, the winding frame 11 and the superconducting coil 13
And expand and contract in the opposite direction in the circumferential direction. Therefore, in the state of being immersed in the cryogenic liquid, the coupling strength between the bobbin 11 and the superconducting coil 13 is significantly strengthened.

When a current is passed through the superconducting coil 13 while the superconducting coil 13 is cooled to a cryogenic temperature, the electromagnetic force generated by this current causes the superconducting coil 13 to be indicated by thick arrows C'and E in FIG. 7 (b). As shown, the amount of contraction in the axial direction is further increased, and it is expanded in the opposite direction in the circumferential direction.

However, since the coupling strength between the bobbin 11 and the superconducting coil 13 is greatly strengthened at the stage of being immersed in the cryogenic liquid, even if the superconducting coil 13 contracts or expands, the bobbin 11 does not expand. The coupling strength between the superconducting coil 13 and the superconducting coil 13 only returns to a state similar to that at the time of manufacturing. Therefore, the coupling state between the winding frame 11 and the superconducting coil 13 is not loosened, and it is possible to suppress the occurrence of quench caused by the movement of the superconductor 12.

However, even the superconducting coil device having the winding frame made of DFRP alone has the following problems.

For example, as an application example of the superconducting coil device, a case of applying it to a superconducting current limiting device as disclosed in Japanese Patent Laid-Open No. 168525/1990 will be taken as an example. The superconducting current limiter effectively utilizes the quench of the superconductor.
A superconductor is wound around the outer circumference of the winding frame in a non-inductive winding, and this is used as a current limiting element. Then, a current limiting element is connected in series to the line, and when the line current flowing through this current limiting element exceeds the critical current of the superconductor, the superconductor forming the current limiting element is quenched, and with this quench It functions as a current limiting device due to the rapid increase in resistance of the superconductor.

As described above, when applied to the superconducting current limiting device, since the superconductor becomes a resistor at the moment when the quench occurs, a large Joule heat is generated which is determined by the resistance value and the energizing current. Due to this Joule heat, the cryogenic liquid typified by liquid helium evaporates rapidly, and a high-pressure gas region is generated around the winding frame. The pressure in this area reaches 10 kg / cm ² locally, and acts as a large external force on the bobbin.

The elastic modulus of DFRP is not sufficient to meet the current limiting withstand capability. Therefore, when a large external force is applied as described above, the reel is elastically deformed. When the reel is elastically deformed, the superconductor is displaced from the stable position up to that point during this deformation. As a result, the superconductor is likely to move to the next stable position when the superconductor is turned on again after the superconducting transition. When the superconductor moves, frictional heat is generated as described above, and this frictional heat causes quenching of the superconductor. Since this phenomenon is repeated, the current value at which the current limiting element can be energized, that is, the rated current value of the current limiting element is necessarily suppressed to a small value.

As described above, when the superconducting coil device having the winding frame made of DFRP alone is applied to the application of a large external force to the winding frame such as the superconducting current limiting device, the DFRP Due to the small elastic modulus,
There is a problem that the quenching prevention function of the DFRP reel cannot be effectively utilized.

[0029]

As mentioned above, the GFRP
In the case of the reel made of DFRP or the reel made of DFRP, there is a problem that the instability of the superconducting coil cannot be avoided.

Therefore, an object of the present invention is to provide a bobbin for a superconducting coil which can solve the above-mentioned problems.

[0031]

To achieve the above object, the present invention comprises a matrix resin, a polyethylene fiber having a negative coefficient of thermal expansion in the fiber direction, and a reinforcing material having a larger elastic coefficient than the polyethylene fiber. A winding frame for a superconducting coil made of a fiber-reinforced plastic material, characterized in that the polyethylene fibers are oriented within a range of ± 35 ° to 90 ° with respect to the axis of the winding frame.

The polyethylene fiber has a strength of at least 1.32 GPa or more and an elastic modulus of at least 23.9 GPa.
It is preferable to have characteristics of GPa or more.

The reinforcing material has a strength of at least 12
Alumina fibers having a characteristic of an elastic modulus of 00 MPa or more and at least 120 GPa or more are preferable.

The mixing ratio of the alumina fibers to the polyethylene fibers is 5:95 to 75:25, preferably
It is preferably contained in the fiber-reinforced plastic in the range of 10:90 to 65:35.

Further, it is preferable that the winding frame is provided with a spiral groove for accommodating and fixing the superconductor on the outer peripheral surface portion.

Further, it is preferable that the reel be provided with a passage on the outer peripheral surface for guiding the cryogenic liquid for cooling the superconductor.

The fiber-reinforced plastic material used in the present invention includes a roving strand of polyethylene fiber having a negative coefficient of thermal expansion, a unidirectional reinforcing fiber sheet or a fabric sheet, and a reinforcing material having a larger elastic coefficient than polyethylene fiber (hereinafter referred to as " HMA ").

In such a fiber-reinforced plastic material, the angle between the polyethylene fiber and the axis of the winding frame, that is, the winding angle θ is set within the range described later.

The HMA morphology can be selected from the group consisting of filaments, staple fibers and particles.
Examples of HMA can include alumina, carbon, silica, zirconia, silicon carbide, titania and silicon nitride. A high-strength alumina fiber is preferable, and an alumina fiber (AF) having a strength of at least 1200 MPa or more and an elastic modulus of at least 120 GPa or more is preferable.

When alumina short fibers or particles are used as the HMA, DF is molded into a unidirectional reinforcing fiber sheet or fabric sheet, impregnated with a matrix resin containing alumina short fibers or particles, and Wrap it around in a cylindrical shape.

High tensile alumina fiber, ie AF
When used as, the DF and AF can be wound around the axis of the reel to form a roving strand impregnated with the matrix resin. The combination of DF and AF is
For example, by winding a preformed roving strand from DF and AF mixed in a filament unit or yarn unit, or D
This can be achieved by alternately winding the roving stands of F and AF and forming layers of both roving strands alternately.

The mixing ratio of AF and DF in the roving strand is in the range of 5:95 to 75:25, preferably 10:90 to 65:35 in order to maximize the characteristics of AF and DF. To do.

As can be seen from FIG. 6, for DF and AF,
Or at least DF roving strand, ±
It is necessary to wind around the axis of the reel at a winding angle θ in the range of 35 ° to 90 °, preferably ± 43 ° to 90 °, and more preferably ± 80 ° to 90 °. The method of winding the roving strand around the rotating mandrel (and thus around the axis of the reel) is not particularly limited, and the winding angle θ
The roving strands can be wound by a conventional spiral winding method, which is constant within the range of ± 35 ° to 90 ° except at both ends of the mandrel.

The roving strands can be impregnated with a matrix resin immediately before winding on a mandrel (wet winding) or pre-impregnated with a partially cured matrix resin (dry winding). The roving strands can be positioned, for example, by means of a feeder arm arranged in front of the rotating mandrel. The feeder arm is reciprocated at a constant speed over the entire length of the mandrel parallel to the axis of the mandrel.

At the end of the winding process, the entire fixture is cured in an oven, after which the mandrel is removed. The cylindrical molded body thus obtained is machined to form flanges at both ends, and as a result, a superconducting coil bobbin is obtained.

The preparation of DF is not particularly limited, and commercially available DF can be purchased, and for example, JP-A-56-15408 and JP-A-58-52.
It can also be produced by a well-known method as described in Japanese Patent Publication No. 28. For example, a weight average molecular weight of at least 100,000 or more, preferably at least 1,000,
000 or more plastic high molecular weight polyethylene is dissolved in decalin to form a spinning solution, and the spinning solution is extruded into the air or water through a spinning nozzle and cooled to form a decalin-containing gel fiber. Next, this gel fiber is drawn by single-step or multi-step drawing at a total draw ratio of 30 to 40 to obtain a desired DF. The DF thus obtained has at least strength.
It is 1.32 GPa or more and the elastic modulus is at least 23.9 GPa or more.

As described above, DF has a unique property that it expands in the longitudinal direction of the fiber with a decrease in temperature, which is different from ordinary glass fiber or ceramic fiber.

On the other hand, for example, AF has a very large elastic coefficient as compared with GF and DF. AF material is high purity A
l ₂ O ₃ (purity 99.5 wt% or more, alumina having α-type crystal structure), Al ₂ O ₃ —SiO ₂ (purity 80 to 85 wt
%, Alumina having a γ or δ type crystal structure) and Al ₂ O ₃ —B ₂ O ₃ (purity 80 to 85 wt%).

In order to obtain a reel having extremely excellent characteristics,
It is desirable to use high-purity Al ₂ O ₃ having an α-type crystal structure. From the viewpoint of handling, Al ₂ O ₃ —SiO ₂ having a γ or δ type crystal structure is preferable.
Alumina fibers having an α-type crystal structure have a strength of at least 1500 MPa, preferably at least 1800 MP.
It is desirable that it has a or more and an elastic modulus of at least 300 GPa or more, preferably at least 330 GPa or more. Alumina fibers having a γ-type crystal structure have a strength of at least 1500 MPa or more, and preferably at least 1800.
It is desirable that the material has a MPa or more and an elastic modulus of at least 200 GPa or more, preferably at least 210 GPa or more. Alumina fibers having a δ type crystal structure have a strength of at least 1300 MPa or more, and preferably at least
It is desirable that the elastic modulus is 1600 MPa or more and the elastic modulus is at least 150 GPa or more, preferably at least 160 GPa or more.

The preferred reel is made of fiber reinforced plastic material containing DF and AF roving stands in a matrix as described above. Therefore, such a bobbin has the characteristics of AFRP that it is difficult to cause distortion due to external stress due to its large elastic coefficient, and also has the characteristics of DFRP that expands in the circumferential direction when cooled to an extremely low temperature. Therefore, this reel can satisfactorily exhibit the function of preventing the occurrence of quenching even when subjected to external stress at extremely low temperatures.

Examples of the matrix resin include epoxy resin, urethane resin, unsaturated polyester resin, vinyl ester resin and urethane acetate resin. Most preferred is an epoxy resin.

The volume fraction (Vf) of the fibers in the reel is preferably 25% to 85%, more preferably 35% to 75%.

The reel obtained under the above conditions has a circumferential elastic modulus of at least 20 GPa or more, preferably at least 30 GPa or more. This is according to the invention
This means that it is possible to obtain a highly elastic winding frame for superconducting coils.

The bobbin is preferably provided on its outer edge with a spiral groove for keeping the superconductor wound around the bobbin and / or a longitudinal channel for guiding the cryogenic liquid to cool the superconductor.

[0055]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a superconducting coil device incorporating a winding frame according to an embodiment of the present invention.

This superconducting coil device is roughly divided into
It comprises a winding frame 21 and a superconducting coil 23 formed by winding a superconductor 22 around the winding frame 21.

The reel 21 is a tubular plastic molded body (hereinafter referred to as ADFR) reinforced by winding a roving strand of AF and DF with an epoxy resin as a matrix.
It is abbreviated as P. ), The flanges 24a and 24b are provided at both ends, and the flanges 24a and 24b are
A spiral groove 25 is provided on the outer surface of the portion located between 24b. Further, a plurality of flow channel grooves 26, which are deeper than the spiral groove 25 and extend in the axial direction, are circumferentially formed on the outer surface of the portion located between the flanges 24a and 24b. Hole 2 communicating with the end of the groove 26
7 are formed.

The superconductor 22 is partially wound into the spiral groove 25, and is wound like a solenoid with a constant tension.

Here, a specific example will be described.

[Example 1] First, AF and DF (trade name, Dyneema, SK-60, manufactured by Toyobo Co., Ltd.) were prepared as filaments of ADFRP constituting the reel 21, and epoxy was used as a matrix. Prepare a resin and set the AF and DF to AF /
The yarn was mixed at DF = 40/60 (volume ratio), and while the roving strand was impregnated with epoxy resin, the winding angle was set to ± 75 degrees by a spiral winding method and the winding was wound around a mandrel to form a cylindrical body. .

The cylindrical body was kept at 100 ° C. for 2 hours and then kept at 130 ° C. for 3 hours to be cured to obtain a cylindrical ADFRP molded body as shown in FIG. 5 (a). At this time, Vf was 65%.

When the circumferential thermal strain and the circumferential elastic modulus of this ADFRP molded product from room temperature to liquid nitrogen temperature were measured, they were +700 με and 73 GPa, respectively.

Next, the flanges 24a and 24b are formed on both ends of the ADFRP molded body by machining, and the spiral groove 25 is formed on the outer surface of the portion located between the flanges 24a and 24b, and subsequently extends in the axial direction. Channel groove 26
Are formed in the circumferential direction, and the flanges 24a and 24b are further formed.
A hole 27 communicating with the end of each channel groove 26 is provided.

In this way, the inner diameter is 210 mm and the outer diameter is 220 mm.
A reel 21 having a length of 400 mm and an axial length of 400 mm was obtained. A superconducting coil device was completed by winding a superconductor 22 having a wire diameter of 2.5 mm with a constant tension so as to be fixed by the spiral groove 25 of the winding frame 21.

Here, an example of measuring the circumferential thermal strain and the circumferential elastic coefficient over the range of room temperature to liquid nitrogen temperature of the reel will be described.

1. Circumferential thermal strain A strain gauge is attached to the outer edge of the reel and connected to the bridge box or recorder. The reel is immersed in liquid nitrogen to equilibrate, and the value of thermal strain is read from the recorder in this state.

2. Circumferential direction elastic modulus (or circumferential direction Young's modulus) Unidirectional fiber reinforced plastic material (hereinafter "UD-FP
The plate made of P ″ is used under the same conditions (matrix resin, DF and HMA) as those used for manufacturing the cylindrical bobbin.
Type, mixing ratio of HMA and DF, fiber volume fraction, etc.)
Of prepared under a tensile tester fiber longitudinal Young's modulus of the plate at room temperature by (E _L), the fiber transverse Young's modulus (E _T), stiffness coefficient G _LT), the fiber longitudinal Poisson's ratio (v _L) , Fiber transverse Poisson's ratio (v _T ) is examined.
These measured values are calculated using the following formula (Uemura, J, PPn.Aero Space
Sci. 24, 496 (1976)) to calculate the circumferential elastic modulus or Young's modulus (E _y ) of the cylindrical bobbin.

[0069] _{1 / E y = 1 / E} y -Ψ 2 G xy 1 / E y = m 4 / E L + l 4 / E T + (1 / G LT -2V L / E L) l 2 m 2 1 _{/ G xy = 4 [(1} + V L) / E L + (1 + V T) / E T] l 2 m 2 + (l 2 -m 2) / G LT Ψ = 2 [l 2 / E T -m 2 / _{E L + (1 / G LT} -2V L / E L) (l 2 -m 2) / 2] lm l = cos θ m = sin θ here, the stiffness coefficients of G _xy is cylindrical bobbin, theta is It is the winding angle.

Example 2 Using the same composition and method as in Example 1, the winding angle θ of the roving strand with respect to the axis of the mandrel was set to ± 85 ° to form a cylindrical body. This cylindrical body was cured in the same manner as in Example 1 to obtain a cylindrical ADFRP molded body.

When the circumferential thermal strain and the circumferential elastic modulus of this ADFRP molded product from room temperature to liquid nitrogen temperature were measured, they were +400 με and 92 GPa, respectively.

The flanges 24a and 24b are formed on both ends of the ADFRP molded body by machining, and the spiral groove 25 is formed on the outer surface of the portion located between the flanges 24a and 24b, and then the channel groove extending in the axial direction is formed. A plurality of holes 26 are formed in the circumferential direction, and the flanges 24a and 24b are further provided with holes 27 communicating with the ends of the flow channel grooves 26.

In this way, the inner diameter is 210 mm and the outer diameter is 220
A reel 21 having a length of 400 mm and an axial length of 400 mm was obtained. The wire diameter is 2.5 so that it can be housed and fixed in the spiral groove 25 of the reel 21.
The superconducting coil device was completed by winding the superconductor 22 of mm with a constant tension. [Comparative Example 1] The same DF as that used in Examples 1 and 2 was prepared, an epoxy resin was prepared as a matrix, and the winding angle θ was determined by a spiral winding method while impregnating the DF roving strand with the epoxy resin. It was wound around a mandrel set to ± 60 degrees to form a cylindrical body. This cylindrical body was used in Example 1,
It was cured in the same manner as in 2 to obtain a cylindrical DFRP molded body.

When the circumferential thermal strain and the circumferential elastic modulus of this DFRP molded product from room temperature to liquid nitrogen temperature were measured, they were +2000 με and 11 GPa, respectively.

Flanges are formed at both ends of this DFRP molded body, spiral grooves are formed on the outer surface of the portion located between the flanges, and a plurality of axially extending flow passage grooves are formed in the circumferential direction. A hole communicating with the end of each flow channel was provided.

In this way, DFRP reels having the same dimensions and shapes as those of Examples 1 and 2 were obtained. A superconducting coil device was completed by winding a superconductor having a wire diameter of 2.5 mm with a constant tension so as to be fixed in the spiral groove of the winding frame.

Comparative Example 2 Using the same composition and method as in Example 1, the winding angle θ of the roving strand with respect to the axis of the mandrel was set to ± 30 ° to form a cylindrical body. This cylindrical body was cured in the same manner as in Example 1 to obtain a cylindrical ADFRP molded body.

When the circumferential thermal strain and circumferential elastic modulus of this ADFRP molded product were measured from room temperature to liquid nitrogen temperature, they were -5400 με and 11 GPa, respectively.

Flange is formed at both ends of this ADFRP molded product, spiral grooves are formed on the outer surface of the portion located between the flanges, and a plurality of axially extending flow passage grooves are formed in the circumferential direction. A hole communicating with the end of each flow channel was provided.

In this way, ADFRP reels having the same dimensions and shapes as those of Examples 1 and 2 were obtained. A superconducting coil device was completed by winding a superconductor having a wire diameter of 2.5 mm with a constant tension so as to be fixed in the spiral groove of the winding frame.

The four superconducting coil devices obtained as described above were dipped in liquid helium, and the changes in quench current were measured by the training method.

The results of these measurements are shown in FIG.

In FIG. 2, □ indicates the above-mentioned embodiment 1 (θ = ±
75 °) is shown, and the filled □ mark indicates that in Example 2 (θ = ± 85
The results are shown in FIG. 8), the mark ◯ indicates the result of Comparative Example 1, and the mark ● indicates the result of Comparative Example 2.

In Comparative Example 1 using the reel made of DFRP,
Even if the number of training is increased, the upper limit of energizing current is 1800A
It could not be improved further.

On the other hand, in Example 1 using the ADFRP reel, Comparative Example 1 was performed by training about 30 times.
It has become possible to energize up to 2400A, which is 30% larger. This is because the addition of AF improved the elastic modulus of the reel, and the distortion of the ADFRP reel due to external force was reduced to about 1/2 of that of the DFRP reel, which made it difficult for the superconductor to move. . Therefore, even when applied to applications such as a superconducting current limiting device in which a large external force is applied to the bobbin, it is possible to utilize the quench prevention function provided in the DFRP.

Further, in Example 2, it was possible to energize to a higher value of 2600A. It is considered that this is because, by increasing the winding angle θ, the rigidity of the winding frame is improved, which in turn leads to higher stabilization of the coil.

Further, in the case of Comparative Example 2, since the winding angle θ is small, the quench prevention function provided in the DFRP cannot be utilized, and the characteristics are similar to those of the DFRP reel shown in Comparative Example 1. I couldn't get it.

Although not shown, it was confirmed that when the winding angle θ of the roving strand was set to approximately ± 35 degrees to form an ADFRP molded body, the characteristics close to those in Examples 1 and 2 were obtained. There is.

The present invention is not limited to the above example. In the above-described example, the entire winding frame including the flange is formed of ADFRP, but in consideration of workability, the portion where the spiral groove 25 and the flow channel groove 26 are formed is formed of an AFRP layer or a GFRP layer. It may be formed, and the inner part, which is a so-called reel body, may be formed by ADFRP. Further, the usage example is not limited to the superconducting current limiting device.

[0090]

As described above, according to the present invention,
Even when used under extremely low temperature and under the condition that an external force is applied, the deformation of the bobbin can be suppressed to a minimum, so that the superconducting coil body can be firmly fixed, which contributes to the suppression of quenching.

[Brief description of the drawings]

FIG. 1A is a vertical sectional view of a superconducting coil device incorporating a winding frame according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line AA in FIG.

FIG. 2 is a diagram showing a quench characteristic of the superconducting coil device in comparison with a characteristic of a conventional device.

FIG. 3 is a diagram for explaining a problem of a conventional superconducting coil device using a winding frame made of GFRP.

FIG. 4 is a diagram showing a heat shrinkage amount (however, a metal is a characteristic of itself) of a fiber-reinforced plastic molded product made of a polyethylene fiber and various fibers that have been strengthened.

5A is a perspective view showing an example of a DFRP molded body or an ADFRP molded body, and FIG. 5B is a view for explaining a winding angle when the molded body is manufactured.

FIG. 6 ADFRP molded product, DFRP molded product and GF
The figure which shows the relationship between the winding angle of RP molded object, and a thermal expansion coefficient.

FIG. 7 is a diagram for explaining the operation of a superconducting coil device using a winding frame made of DFRP at low temperature.

[Explanation of symbols]

 21 ... Reel 22 ... Superconductor 23 ... Superconducting coil 25 ... Spiral groove 26 ... Flow channel 27 ... Hole

Front page continuation (72) Inventor Masahiko Nakade 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Tokyo Electric Power Co., Inc. Electric Power Technology Laboratory (72) Inventor Takeshi Okuma 4-1-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 Electric Power Technology Research Institute, Tokyo Electric Power Co., Inc. (72) Kenji Tazaki, 1 Komukai Toshiba Town, Sachi-ku, Kawasaki City, Kanagawa Prefecture Research & Development Center, Toshiba Corp. (72) Inventor, Takashi Yazawa Ko, Kawasaki City, Kanagawa Prefecture Muko Toshiba Town No. 1 Incorporated company Toshiba Research & Development Center (72) Inventor Hideaki Maeda Komukai-shi, Kawasaki City, Kanagawa Prefecture Komu Toshiba No. 1 Ltd. Corporate Research & Development Center (72) Inventor Eriko Yoneda Kawasaki Kanagawa Komukai-Toshiba-cho, Koichi-shi, Toshiba Corporation R & D Center, Inc. (72) Inventor Shunji Nomura 1-Komikai-Toshiba, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Toshiba Research and Development Center (72) Inventor Toshihiro Kashima 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd. achievements overall in the Institute (72) inventor Atsuhiko Yamanaka Otsu, Shiga Prefecture Katata chome No. 1 No. 1, manufactured by Toyobo Co., Ltd. achievements Research Institute in

Claims (6)

[Claims] 1. A reel formed of a fiber-reinforced plastic material containing a matrix resin, polyethylene fibers having a negative coefficient of thermal expansion in the fiber direction, and a reinforcing material having a larger elastic coefficient than the polyethylene fibers. A bobbin for a superconducting coil, wherein the polyethylene fibers are oriented within a range of ± 35 ° to 90 ° with respect to the axis of the. 2. The polyethylene fiber has a strength of at least 1.32 GPa and an elastic modulus of at least 23.9 GPa.
The superconducting coil bobbin according to claim 1, having the above-mentioned characteristics. 3. The reinforcing material has a strength of at least 1200 MP.
An alumina fiber having a characteristic of a or more and an elastic modulus of at least 120 GPa or more.
The bobbin for the superconducting coil described in. 4. The mixing ratio of the alumina fiber with the polyethylene fiber is 5:95 to 75:25, preferably 10:90.
The reel for a superconducting coil according to claim 3, wherein the fiber-reinforced plastic is contained in the range of up to 65:35. 5. The winding frame for a superconducting coil according to claim 1, further comprising a spiral groove for accommodating and fixing the superconductor on the outer peripheral surface portion. 6. The winding frame for a superconducting coil according to claim 1, wherein a passage for guiding a cryogenic liquid for cooling the superconductor is provided on the outer peripheral surface portion.