JP3782707B2 - Electromagnetic coil and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic coil used for a radiation-resistant electromagnet or the like, and more particularly to an insulation configuration between conductors constituting the electromagnetic coil and a method for realizing it.
[0002]
[Prior art]
Various accelerators are used to accelerate charged elementary particles and ions to a high energy state and collide with the target to study the structure of the nucleus. In this apparatus, Lorentz force is used for acceleration of elementary particles or ions and direction control, so it is necessary to install a large number of electromagnets for generating a high magnetic field. And in an accelerator, generation | occurrence | production of the various radiation accompanying particle acceleration is unavoidable, and the countermeasure with respect to a radiation is needed also about the electromagnet to be used.
[0003]
For this reason, in consideration of deterioration of an insulator due to radiation, a technique for configuring an electromagnetic coil using an inorganic insulating metal-coated cable called MIC (Mineral Insulated Cable) is disclosed. By the way, in order to generate a pulse magnetic field in the electromagnets described above, alternating current may be used, which may require insulation with an organic polymer compound.
[0004]
In other words, in order to reduce eddy current loss due to energization of alternating current, it is necessary to use a strand conductor, but in this case, it is natural to ensure insulation between the strand conductors in the winding. As a result, insulation between the strands constituting the strand conductor contributes to loss reduction.
[0005]
In order to satisfy such required characteristics, a tape made of glass fiber from which boron has been removed is impregnated with a polyimide resin (hereinafter referred to as prepreg), and the strand conductor is wound horizontally, that is, spirally wound. An electromagnetic coil is disclosed in which an insulation treatment is performed and then wound into a winding, and a prepreg is wound on the outer periphery of the winding and impregnated with a polyimide resin.
[0006]
The polyimide resin is impregnated in order to fill the gaps between the strand conductors and the gaps between the strands constituting the strand conductors with an insulating material, but a thermosetting polymer material such as a polyimide resin. However, it has thermoplasticity before the curing reaction is completed, and the effect is often not sufficiently exhibited due to the outflow after the impregnation operation.
[0007]
For this reason, the polyimide resin may be mixed with an inorganic powder having an insulating property such as a metal oxide to adjust the apparent viscosity coefficient. That is, by mixing an appropriate amount of an inorganic powder having an appropriate average particle diameter into the polyimide resin, the polyimide resin becomes difficult to flow and hardly flows out from the gap between the conductors, and functions as an insulating material.
[0008]
4A and 4B are diagrams schematically showing a state where the strand conductor is insulated by horizontal winding of a prepreg, FIG. 4A is a perspective view, and FIG. 4B is a cross-sectional view. In FIG. 4, 400 is a strand conductor, 401 is an element wire made of copper constituting the strand conductor, 402 is an aluminum cooling water passage pipe, and 403 is a prepreg.
[0009]
FIG. 5 is a view showing a state in which the prepreg is wound on the outer periphery after winding the strand conductor on which the prepreg is wound. In FIG. 5, reference numeral 501 denotes a strand conductor that has been subjected to insulation treatment by horizontal winding of a prepreg, and 503 denotes a prepreg.
[0010]
However, even if the insulation is performed by the method as described above, the insulation between the layers is not always sufficient, and it is difficult to load a certain voltage or more to the electromagnetic coil because of the possibility of the insulation breakdown between the layers. This is because even when the prepreg is wound on the strand conductor, the difference in expansion and contraction between the outer peripheral side and the inner peripheral side is large at the portion where the radius of curvature is small when winding the conductor to form the winding. Since the insulation thickness on the outer peripheral side decreases and the portion where the adjacent strand conductors contact in the direction of pressure is applied, the prepreg sandwiched between the layers and the strands constituting the strand conductor are in line contact or point contact. It is presumed that the destruction is likely to occur.
[0011]
[Problems to be solved by the invention]
Therefore, the technical problem of the present invention is to provide a method for improving the reliability of interlayer insulation and preventing the occurrence of interlayer dielectric breakdown in order to solve the above-mentioned problems in the electromagnetic coil.
[0012]
[Means for Solving the Problems]
The present invention has been made as a result of studying the use of a prepreg as an insulating component by a method other than horizontal winding around a strand conductor in order to solve the above problems.
[0013]
That is, the present invention includes a first step of placing a prepreg impregnated with a polyimide resin on a glass fiber tape obtained by removing boron on at least one of the opposing side surfaces of a strand conductor having a substantially square cross-sectional shape; A second step of horizontally winding a prepreg different from the prepreg along the strand conductor, and a side parallel to the prepreg arranged in a direction perpendicular to the bending direction, the layer is parallel to the plane parallel to the bending direction. A third step of forming a winding by winding while inserting an insulating layer, a fourth step of applying a prepreg horizontal winding to the outer periphery of the winding, and a fifth step of applying a terminal treatment to the winding It is the manufacturing method of the electromagnetic coil characterized by including.
[0014]
Moreover, this invention is a manufacturing method of the said electromagnetic coil, The strand which comprises the said strand conductor consists of either copper or aluminum, The manufacturing method of the electromagnetic coil characterized by the above-mentioned.
[0015]
Moreover, this invention is an electromagnetic coil characterized by the said strand conductor having a pipe for passing cooling water in the manufacturing method of the said electromagnetic coil.
[0016]
Further, according to the present invention, in the electromagnetic coil manufacturing method, the gap between the strand conductors and the strand conductors are made of polyimide resin containing inorganic powder after the step of applying the prepreg to the outer periphery of the winding. The electromagnetic coil manufacturing method is characterized by impregnating a gap between strands and curing.
[0017]
The present invention also provides a strand conductor having a substantially square cross-sectional shape, and a glass fiber formed by removing boron, disposed on at least one side surface in a direction perpendicular to the bending direction of the winding made of the strand conductor. A prepreg impregnated with polyimide on the tape, a prepreg laterally wound on the strand conductor, a prepreg laterally wound on the outer periphery of the winding made of the strand conductor laterally wound with the prepreg, and a bending direction of the winding An interlayer insulating layer disposed on a plane parallel to the surface, and a polyimide resin containing an inorganic powder filled in a gap between the strand conductors and a gap between the strands constituting the strand conductor, It is an electromagnetic coil manufactured with the said manufacturing method.
[0018]
[Action]
In the electromagnetic coil according to the present invention, the outer periphery of the winding formed by the strand conductor and the strand conductor is subjected to insulation treatment by horizontal winding of a prepreg, and insulating layers are inserted in both vertical and horizontal directions between layers. Therefore, operation at a higher voltage is possible as compared with a conventional electromagnetic coil.
[0019]
Moreover, these interlayer insulating layers are not simply increased in the thickness of the prepreg that is horizontally wound, but are separately inserted in both the longitudinal and lateral directions, so that the influence of expansion and contraction of the inner and outer circumferences when winding the strand conductor is exerted. Therefore, it has a higher insulating function than a prepreg sowed horizontally. In particular, in the lateral direction, that is, in the direction parallel to the direction of bending for winding the strand conductor, a sheet made of prepreg or the like is cut in advance according to the shape of the winding and inserted between the layers. Reliability can be expressed.
[0020]
In addition, since the interlayer insulation layer in the vertical direction is preliminarily wound with a tape made of prepreg in the length direction of the strand conductor, the prepreg is laterally wound. Since it is not performed, it is not necessary to consider misalignment, and workability can be improved.
[0021]
The reason why the glass fiber tape used for the prepreg does not contain boron is that boron absorbs thermal neutrons and damages the surrounding glass fibers and polyimide resin. That is, boron those atomic weight of 10 ⁽¹⁰ B) and 11 ones ⁽¹¹ B) are present in a ratio of 19.9 / ^80.1, when the ¹⁰ B absorbs thermal neutrons, as recoil This is because α rays and ⁷ Li are generated, and their ranges are 5 μm and 2 μm, respectively, and thus affect the surrounding substances.
[0022]
In addition, polyimide resin is used as an insulating material to be impregnated into the glass fiber tape or filled between conductors. Among polymer materials, polyimide resin is least deteriorated when exposed to radiation. Because.
[0023]
The inorganic powder to be mixed with the polyimide resin filled between the conductors is not particularly limited as long as it is obtained in a powder form, and examples thereof include magnesium oxide and calcium carbonate. Among them, silicon oxide, that is, silica is preferable from the viewpoints of availability, cost, and chemical stability.
[0024]
In order to ensure proper fluidity for filling between conductors, the inorganic powder to be mixed into the polyimide resin has an average particle size of 1.5 μm or less, and the mixing amount with respect to the polyimide resin is 5 to 15% by weight. It is necessary to. In general, inorganic materials or organic fibers and powders are mixed with polymer materials to improve mechanical strength. In this case, mixing inorganic powders is also a secondary effect. As such, it can be expected to contribute to the prevention of cracks in the polyimide resin.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings with specific examples.
[0026]
FIG. 1 is a diagram schematically showing a cross section of a part of a winding in an example of an electromagnetic coil according to the present invention. In FIG. 1, reference numeral 100 denotes a strand conductor having a substantially square cross section. Further, 101 is a strand constituting the strand conductor, 102 is a cooling water passage pipe, 103 is a prepreg wound horizontally around the strand conductor, 104 is a longitudinal interlayer insulation layer, 105 is a transverse interlayer insulation layer, 106 Is a prepreg wound horizontally on the outer periphery of the winding.
[0027]
2A and 2B are diagrams showing a state where the strand conductor prepreg is subjected to horizontal winding, in which FIG. 2A is a perspective view of the whole and FIG. 2B is a cross-sectional view. In FIG. 2, another prepreg is horizontally wound while the prepreg is placed as an interlayer insulating layer on one side surface of the strand conductor. In FIG. 2, reference numeral 200 denotes a strand conductor, 201 denotes a strand constituting the strand conductor, 202 denotes a cooling water passage pipe, 203 denotes a prepreg, and 204 denotes a prepreg as an interlayer insulating layer.
[0028]
In the present embodiment, as shown in FIG. 2, the strand conductor is arranged so that the interlayer insulation layer 204 in FIG. 2 is arranged on the inner side after the arrangement of the interlayer insulation layer and the horizontal winding of the prepreg. A conductor is wound to form a winding. At this time, an interlayer insulating layer made of prepreg and indicated by 105 in FIG. 1 is disposed on a plane parallel to the direction in which the conductor is bent. As a result, the same effect as that obtained by arranging the interlayer insulating layers in both the vertical and horizontal directions separately from the horizontal winding of the prepreg in the vertical direction can be obtained.
[0029]
The windings thus formed were immersed in a sealable container filled with a polyimide resin in which 10% by weight of silica powder having an average particle diameter of 1.2 μm was mixed, and impregnated with polyimide. This operation was performed by depressurizing the container using a vacuum pump so that the polyimide resin sufficiently impregnates the gap between the conductors. After the impregnation, a pressure of 150 kPa was applied inside the container so that the polyimide resin sufficiently penetrated between the conductors. Thereafter, using a high-temperature bath, pre-curing and post-curing of the polyimide resin were performed under the conditions of 120 ° C. × 6 hours and 150 ° C. × 4 hours, respectively.
[0030]
FIG. 3 is a view showing the appearance of the winding obtained in this way. Thereafter, a bus bar was attached to energize this winding, or a piping component for passing cooling water was attached to obtain an electromagnetic coil.
[0031]
【The invention's effect】
As described above, according to the present invention, by providing an interlayer insulating layer, insulation deterioration is extremely small even in an environment where alternating current is applied and exposed to radiation, and furthermore, based on interlayer dielectric breakdown and eddy current loss. An electromagnetic coil with very little loss can be obtained. Since the electromagnetic coil according to the present invention has the above-described features, it can be operated at a higher voltage than the conventional one and is extremely useful.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a cross section of a part of a winding in an example of an electromagnetic coil according to the present invention.
FIG. 2 is a diagram showing a state where a strand conductor prepreg is subjected to horizontal winding, FIG. 2 (a) is an overall perspective view, and FIG. 2 (b) is a cross-sectional view.
FIG. 3 is a diagram showing the appearance of a winding.
4A and 4B are diagrams schematically showing a state where a strand conductor is insulated by horizontal winding of a prepreg, FIG. 4A is a perspective view, and FIG. 4B is a cross-sectional view.
FIG. 5 is a view showing a state in which a prepreg is wound on the outer periphery after winding a strand conductor that has been wound with prepreg.
[Explanation of symbols]
100, 200, 400, 501 Strand conductors 101, 201, 401 Strands 102, 202, 402 Cooling water passage pipes 103, 106, 203, 403, 503 Prepregs 104, 105, 204 Interlayer insulation layer

Claims (5)

A first step of placing a prepreg impregnated with a polyimide resin on a glass fiber tape obtained by removing boron on at least one of the opposing side surfaces of a strand conductor having a substantially square cross-sectional shape; and along the strand conductor The second step of horizontally winding a prepreg different from the prepreg and the side along the prepreg arranged perpendicular to the bending direction while inserting an interlayer insulating layer in a plane parallel to the bending direction A third step of winding to form a winding, a fourth step of applying a prepreg horizontal winding to the outer periphery of the winding, and a fifth step of applying a terminal treatment to the winding. A method of manufacturing an electromagnetic coil. 2. The method of manufacturing an electromagnetic coil according to claim 1, wherein the strand constituting the strand conductor is made of copper or aluminum. 3. The electromagnetic coil manufacturing method according to claim 1, wherein the strand conductor has a pipe for passing cooling water. 4. The electromagnetic coil manufacturing method according to any one of claims 1 to 3, wherein after the step of applying a prepreg to the outer periphery of the winding, a polyimide resin containing inorganic powder is added to the gap between the strand conductors and A method for producing an electromagnetic coil, comprising impregnating a gap between strands constituting a strand conductor and curing the strand. A strand conductor having a substantially square cross-sectional shape and a glass fiber tape formed by removing boron and disposed on at least one side surface in a direction perpendicular to the bending direction of the winding made of the strand conductor is impregnated with polyimide. A prepreg laterally wound around the strand conductor, a prepreg laterally wound around the outer periphery of the winding made of the strand conductor laterally wound with the prepreg, and a plane parallel to the bending direction of the winding. 5. An interlayer insulating layer formed from a polyimide resin containing an inorganic powder filled in a gap between the strand conductors and a gap between the strands constituting the strand conductor. The electromagnetic coil manufactured with the manufacturing method in any one of.

Images