The present patent application claims the benefit under 35 U.S.C. 119 of Japanese Patent Application No. 2010-166630 filed on Jul. 26, 2010, the disclosure of which is incorporated into this patent application by reference.
1. Field of the Invention
The present invention relates to a superconducting coil and a superconducting rotating machine, especially the superconducting coil to be used for a stator coil of the superconducting rotating machine and the superconducting rotating machine utilizing the stator.
2. Description of Related Art
The superconducting rotating machine utilizing the superconducting coil of a superconducting material has been known as enabling a rotating machine that is smaller and lighter.
JP2005-176578A discloses a superconducting motor (superconducting rotating machine) with a stator coil of a superconducting coil on a stator. The superconducting coil (stator coil) disclosed in JP2005-176578A consists of a tape of a superconducting material that is coiled in a race-track shape with linear portions and curved portions. In each turn of this superconducting coil, the linear portion of the tape is on the same plane as the curved portion of the tape.
JPH08-236341A discloses a saddle shape superconducting member which has a linear portion of a stator coil is not disposed on the same plane as a curved portion of the stator coil, which is intended to have the linear portion of the stator coil come close to a rotor and not to have the curved portion of the stator abut on stator. JP2009-049040A discloses a coil frame on which a tape of a superconducting material is coiled.
Looking to any of JP2005-176578A, JPH08-236341A and JP2009-0490040A, a shape of a stator tooth, on which a shaped coil is attached, is restricted because there is no way to change a coil shape after the coil is shaped. For example, if the shape of a stator tooth is homogeneous in the radius direction of the super conducting rotating machine like the superconducting motor (superconducting rotating machine) shown in FIG. 2 of JP2005-176578, any of the superconducting coils disclosed in JP2005-176578A, JPH08-236341A and JP2009-049040A can be attached onto the stator tooth without deforming the shape of the superconducting coil.
However if the width of a stator tooth varies in the radius direction of the superconducting rotating machine, it may be difficult to attach any of the superconducting coils disclosed in JP2005-176578A, JPH08-236341A and JP2009-0490040A onto the stator tooth. For instance, if the width of a portion of a stator tooth becomes larger as the portion is farther apart from the center of a rotation axis of a rotor in the radius direction of the superconducting rotating machine, the superconducting coil has to be attached onto the stator tooth while enlarging the coil width and it is difficult to attach any of the superconducting coils disclosed in JP2005-176578A, JPH08-236341A and JP2009-0490040A onto the stator tooth because the shape of any of these superconducting coils can not be changed.
The present invention is intended to provide a superconducting coil whose coil shape can be changed after the coil is shaped and a superconducting rotating machine using the superconducting coil.
In order to realize such a superconducting coil, a superconducting coil of the present invention has a feature of the superconducting coil comprising a superconducting material wire coated with an insulation material and a coil frame on which the superconducting wire is wound, the coil frame comprising a first member being a thin plate in a circular ring shape and a second member jointed with an inner periphery portion of the first member, the first member inner periphery portion extending from the jointed portion toward an outer periphery of the first member, wherein the superconducting material wire is wound between the first member and the second member, which constitute the coil frame.
A superconducting rotating machine of the present invention has a feature that the superconducting rotating machine comprises a stator having a plurality of superconducting coils as described above and a stator frame and a rotor having a magnetic material or a conductor, wherein the plurality of superconducting coils are disposed on an inner circumference of the stator frame as viewed in a direction of a rotation axis of the rotor.
Using the superconducting coil and the superconducting rotating machine with the coil according to the present invention, the superconducting coil whose shape can be modified after it is shaped and the superconducting rotating machine with the superconducting coil are provided, and the resultant super conducting coil can be attached on the stator tooth regardless of the shape of the stator tooth.
Embodiments to practice the present invention are explained in detail with reference to attached drawings hereinafter. An identical sign is put on any of common portions or parts throughout the drawings.
As shown in
<Coil Frame>
The first support member 2 is a ring shaped thin plate and has an opening portion 2a through which the superconducting coil 1 is installed on the tooth 12 of a superconducting rotating machine 10 (See
The second support member 3 is also a ring shaped thin plate, has an opening portion 3a whose diameter is substantially as large as the opening portion 2a and is aligned with the first support member 2 when it is overlaid on the first support member 2. The opening portion 3a has the same function as the opening 2a. As is shown in
<Superconducting Material Wire>
The super conducting material wire 5 is a round shape wire made of, for example, a super conducting material of magnesium diboride, and is coiled on the coil frame 4 between the first support member 2 and the second support member 3 as is shown in
The superconducting material wire 5 is coated with an insulation material and coiled on the coil frame 4 in order to prevent a short-circuited electrical current from flowing to the coil frame 4 and within the coiled superconducting material wire 5. Such an insulation material as a glass fiber having an ability to withstand high temperatures is used for coating the superconducting material wire 5, because the superconducting material wire 5 is heat-treated after coiled (See the step S104 in
<Production Method of Superconducting Coil>
Next, the production method for the superconducting coil for the first embodiment is explained with reference to
At step S101, the first support member 2 is cut out from a metal plate as shown in
At step S102, the second support member 3 is attached to the first support member 2 as shown in
At step S103, the superconducting material wire 5 is wound about the coil frame 4 that is made at step S102 as shown in
Since the superconducting material wire 5 before heat treated as explained above is wound about the coil frame 4, the superconducting material in the superconducting material wire 5 is prevented from breaking due to winding. It should be understood that the hollow superconducting material wire 5 having the magnesium powder and the boron powder filled in the inner space and encapsulated thereinside may be drawn to be thinner while it is undergoing an intermediate heat treatment and wound about the coil frame 4.
At step S104, each coil frame 4 about which is wound the superconducting material wire 5 produced on the in-situ PIT method is put into in a furnace and heat treated (final heat treatment). This heat treatment is performed between 550° C. and 750° C. During the heat treatment, the magnesium powder and the boron powder, which are encapsulated, chemically react with each other, which results in producing magnesium diboride that is a superconducting material. It is preferable that the produced magnesium boride (MgB2) wire be impregnated with resin and fixed to prevent quench due to the superconducting wire being moved. This resin used for fixing the superconducting wire preferably includes fillers to make the thermal conductivity higher to enhance cooling efficiency.
As has been explained, the superconducting coil 1 according to the first embodiment shown in
<Effect>
Now the effect of the superconducting coil 1 according to this embodiment is explained, making a comparison between the production method of the conventional superconducting coil and the production method of the superconducting coil 1 for the present embodiment.
R&W method (react and wind method), according to which the heat treated superconducting wire is wound about stator tooth, and W&R (Wind and method, according to which the superconducting wire is heat treated after wound about stator tooth, have been known as conventional production methods. However if the superconducting wire produced on either of these conventionally known production methods is applied to a superconducting rotating machine, there come out the following problems.
If R&W method is used, the superconducting wire becomes hardened after heat treated and does not have good workability with its critical fracture stress relatively low, the superconducting wire after heat treated could break or deteriorate when it is wound about the stator tooth. Therefore, the superconducting wire produced on R&W method can not be wound about the stator tooth with a large curvature.
If R&W method is used, the stator tooth about which the superconducting wire before heat treated is wound is put in a furnace to be heat treated. Obviously a large capacity furnace is needed to put the whole stator tooth. Moreover because the stator tooth is heat treated as well, the physical property of the stator tooth could change, which results in the superconducting rotating machine having performance degraded.
On the other hand, if the production method on the present embodiment is used, the superconducting material wire 5 is produced on in-situ PIT method and heat treated after the superconducting material wire 5 is wound about the coil frame 4. Accordingly the superconducting material in the superconducting wire 5 is prevented from breaking. Moreover there is no need for a large furnace, the physical property of the stator tooth (iron core) does not change because the stator is not heat treated and the performance of the superconducting rotating machine does not degrade.
Furthermore, the coil frame 4 is deformable because it is made of the first support member 2 and the second support member 3, both of which are in a thin plate shape, and relatively easily attached onto the stator tooth (See
The superconducting coil for the first embodiment may not be limited to what is described above and be modified within the scope of the present invention. Next modified examples of the first embodiment are explained.
In the superconducting coil 1A for the first modified example as shown in
The production method of the superconducting coil 1A for the first modified example is the same as the production step flow of the first embodiment described in
According to this modified first example, it is possible to change the length of the coil frame 4A in the rotor rotation axis direction is changed in accordance with and adjusted to the length of the rotor 20 (See
In the superconducting coil 1b for the second modified example as shown in
Next the production method of the superconducting coil 1B for the second modified example is explained with reference to
At step S201, a first support member 2B is cut out from a metal plate as shown in
At step S202, a plurality of support pieces constituting the second support member 3B are disposed at a predetermined interval on a circumference on an opening portion 2Ba of a first support member 2B as is shown in
At step S203, a superconducting material wire 5B to be a superconducting wire is wound about the coil frame 4B as is shown in
After the production steps as explained are finished, the superconducting coil 1B for the second modified example as is shown in
The second modified example has an effect of reducing a mount of the coil frame material in addition to the effects of the first embodiment already explained.
In the superconducting coil 1C for the third modified example as shown in
The production method of the third modified example is the same as the production step flow of the second modified example as described in
According to this third modified first example, it is possible to change and adjust the length of the coil frame 4C in the rotor rotation axis direction in accordance with the length of the rotor 20 (See
The superconducting coil 1D for the fourth modified example has a feature that a first support member 2D and a second support member 3D constitute a single shaped thin flat plate if the first support member 2D and the second support member 3D are developed with the second support member 3D being straightened. This feature is not found in
Next, the production method of the superconducting coil 1D for the fourth modified example is explained with reference to
At step S301, the first support member 2D and the second support member 3D are integrally cut out from a metal plate as shown in
At step S302, the second support member is bent and folded back in such a way as to have the surface of the second support member 3D face the surface of the first support member 2D as shown in
At step S303, the superconducting material wire 5D is wound about the coil frame 4D produced at step S302. At step S304, the whole coil frame 4D is put in a furnace and the superconducting material wire 5D is heat treated (final heat treatment).
The superconducting wire 1D for the fourth modified example as shown in
The fourth modified example has an effect of reducing an amount of a material used for a coil frame in addition to the effect of the superconducting coil 1 for the first embodiment already explained. Moreover since a coil frame is produced by bending work (See step S102 in
The superconducting coil 1E for the fourth modified example has a feature that a first support member 2E and a second support member 3E constitute a single shaped thin flat plate if the first support member 2E and the second support member 3E with the second support member 3E being straightened. The first support member 2E is in a race track shape and has a couple of semicircular portions connected with each other through a couple of linear portions. These features are not found in
The production method of the superconducting wire 1E for the fifth modified example is the same as the production step flow for the fourth modified example as shown in
According to this fifth modified example, it is possible to change and adjust the length of the coil frame 4E in the rotor rotation axis direction in accordance with the length of each of the teeth 12 of the superconducting rotating machine 10 (See
<Superconducting Rotating Machine>
Next, an explanation is given on a superconducting rotating machine 10 using superconducting coils 1a to 1f for the embodiment of the present invention.
The superconducting machine 10 is provided with a rotor 20 rotating about a rotation axis 21 and a stator 11.
The stator 11 is provided with superconducting coils 1a, 1b, 1c, 1d, 1e, 1f and teeth 12a, 12b, 12c, 12d, 12e, 12f. As shown in
The superconducting rotating machine 10 as shown in
A permanent magnet is used for the rotor 20 if the superconducting coil 10 is a synchronized motor and a squirrel cage conductor is used for the rotor 20 if the superconducting coil 10 is an inductive motor.
The shape of the superconducting coil 1 (1a to 1f) is not limited to a race track shape similar to a rectangular shape and may be any race track shape (See
Next, a superconducting coil according to the second embodiment and a superconducting rotating machine using the superconducting coil is explained.
As shown in
Then, the production method of the superconducting coil 1F according to the second embodiment is explained with reference to
At step S401, the first support member 2F is cut out from a metal plate as shown in
The superconducting coil 1F in the saddle shape for the second embodiment as shown in
The superconducting coil 1G as shown in
At step S501, the first support member 2G and the second support member 3G are cut out as an integral member from a metal plate as shown in
At step S503, the first support member 2G integrally combined with the second support member 3G is bent to be a curved plane 2Gb that is symmetrical with respect to a dashed line as a center line for bending work as indicated in
At step S504, a superconducting material wire 5G to be a superconducting wire 5G is wound about the coil frame 4G produced at step S503 as shown in
As explained above, the superconducting coil 1G for the sixth modified example as shown in
Next, an explanation is given on an example of the superconducting coil 1G for the sixth modified example being used for a stator coil on a superconducting rotating machine. An explanation that is the same as that on the superconducting rotating machine 10 (See
Teeth 12a on one side of U phase are constituted by teeth 121, 122, 123. There are a couple of superconducting coils 1G1, 1G2 attached for the teeth 12a. The superconducting coil 1G1 is attached to enclose the teeth 121, 122 while the superconducting coil 1G2 is attached to enclose the teeth 122, 123. The superconducting coils 1G1, 1G2 are electrically connected in series or parallel with each other. Tooth 12d on the other side of U phase have the same structure as the teeth 12a. Each of teeth of U phase and V phase (12b, 12c, 12e, 12f) has the same structure as the teeth 12a as well.
The superconducting coils 1G1, 1G2 are disposed as explained above and form distributed windings in which part of the superconducting coils 1G1 is disposed overlapped with part of the superconducting coils 1G2. As a result, a waveform of magnetomotive force generated by this stator 11 is made to be closer to a sinusoidal wave. A detailed explanation on the waveform of magnetomotive force on the distribution windings becoming closer to a sinusoidal wave is given in “Schematic Explanation on Induction Generator”, written by Shigehiko TSUBOJIMA and published in 2006 by Tokyo Denki University Press, and skipped.
A couple of superconducting coils 1G1, 1G2, used for the superconducting rotating machine is shown in
According to the superconducting coil of the present invention and the superconducting rotating machine using the superconducting coil, the superconducting coil whose shape can be changed after a coil is formed and the superconducting rotating machine using the superconducting coil are provided. Moreover this superconducting coil is attached to a stator tooth regardless of the shape of the stator tooth.
Number | Date | Country | Kind |
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2010-166630 | Jul 2010 | JP | national |