RU2817293C1 - Strip core - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: strip core comprises a multilayer body including a plurality of sheets of electrical steel laid in an annular form in a side view. Multilayer body includes a plurality of bent portions and a plurality of block-shaped portions at positions between adjacent bent portions. At least one part in the form of a block among a plurality of parts in the form of a block includes a heat transfer path limited by sheets of electrical steel at least in a part between the laid sheets of electrical steel. Heat transfer path is included only in at least one part in the form of a block. Spacer element is provided in at least one part between laid sheets of electrical steel in at least one part in the form of a block among multiple parts in the form of a block. Part of the gap formed between sheets of electrical steel by means of a spacer is a heat transfer path, and the spacer is made of nonmagnetic material.

EFFECT: reduced losses in the core.

15 cl, 5 dwg, 3 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The present invention relates to a tape core.

BACKGROUND OF THE ART

[0002] The tape core is used as a magnetic core of a transformer, a reactor, an anti-interference filter and the like. Nowadays, in transformers, iron loss reduction has become an important issue from the point of view of high efficiency, and iron loss reduction has been studied from various perspectives.

[0003] For example, a low noise winding transformer is disclosed in Japanese Patent Laid-Open Application (JP-A) No. 2017-84889. In this low noise winding transformer, the outer periphery of a core made of steel sheets wound in a spiral shape is formed by winding the tape in a circumferential direction in the winding direction of the steel sheet. The laying direction strip having a vibration loss coefficient η>0.01 is located on the surface side of the circumferential direction strip, between the core and the winding wire wound around the core.

[0004] Moreover, for example, a strip core provided with a strip core body of a substantially rectangular shape is disclosed in JP-A No. 2018-148036. The strip core body in this strip core has a stacked structure of grain-oriented electrical steel sheets of substantially rectangular shape, having flat surface portions and corner portions alternately and continuously in the longitudinal direction, with an angle of 90° formed between two flat surface portions adjacent at each corners The grain-oriented electrical steel sheets have a substantially stacked structure of a rectangular shape in a side view including a portion overlapping in the thickness direction of the sheet. In a side view of grain-oriented electrical steel sheets, each of the corners includes two or more curved portions having a curved shape, with a total bending angle of 90° for all curved portions present in one corner. Moreover, in the side view of the curved part, the radius of the inner surface of the curvature r is greater than 1 mm but less than 3 mm. In addition, the surfaces configured by the surface of the steel sheet on the inner surface and outer surface of the grain-oriented electrical steel sheets include a 180° magnetic region wall parallel to the longitudinal direction; a closure region having a size of 150 μm or less in the longitudinal direction and a size of 30 μm or more in the sheet thickness direction includes a region having separation (delamination) of 0.5 mm to 8 mm in the longitudinal direction and present continuously and straightly in the width direction . The area where the shorting area is located occupies 25% or more of the surface area of the surface of the steel sheet on the inner surface or outer surface.

SUMMARY OF THE INVENTION

Technical problem

[0005] Transformers and the like using tape cores are widely used in electrical and electronic devices, however, the heat generated by iron losses leads to the possibility of damage to the insulating paper placed between the tape core and the winding wires wound around the core. There is a possibility that the insulation paper will tear due to damage, and there is a possibility of insulation breakdown in a transformer whose paper insulation is torn. There is a need to keep the temperature of the strip core as low as possible to prevent damage to the insulating paper. In order to suppress the temperature rise of the strip core in a conventional transformer, since the strip core is located in an oil with insulating properties (insulating oil), the heat in the strip core is dissipated by the reservoir of this insulating oil. However, the insulating oil that promotes heat dissipation is only in contact with the surface of the strip core, so the heat dissipation of the insulating oil only occurs in the surface of the strip core, so that a large amount of heat is not sufficiently dissipated from the strip core.

[0006] An object of the present invention is to provide a strip core capable of maintaining low iron losses and suppressing temperature rise.

Solution

[0007] The inventors of the present invention have extensively studied the suppression of temperature rise of the strip core and discovered that providing a large heat dissipation surface area on the strip core is important for increasing the dissipation ability of the strip core. They came up with the idea of dissipating heat from stacked electrical steel sheets. However, iron losses tend to increase when there is an excessive increase in separation between stacked electrical steel sheets. As a result of further research, the inventors came to the conclusion of the present invention about strip cores capable of achieving low iron losses and suppressing the temperature rise of the strip core.

[0008] The essence of the aspect of the present invention based on the above-described discoveries is described below.

The strip core according to an aspect of the present invention is provided with a laminated body including a plurality of electrical steel sheets arranged in a ring shape in a side view. The multilayer body includes a plurality of curved portions, and block-shaped portions at positions between adjacent curved portions. One block-shaped portion among the plurality of block-shaped portions includes at least one heat transfer path between stacked electrical steel sheets. The heat transfer path is included only in the at least one block-shaped portion.

Advantages of the invention

[0009] The present invention provides a strip core that exhibits low iron loss and inhibits temperature rise.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a side view illustrating an example of a strip core according to a first exemplary embodiment of the present invention.

Fig. 2 is an enlarged view of part X of FIG. 1, and is a diagram illustrating an example of a strip core according to the first exemplary embodiment.

Fig. 3 is an enlarged view of part X of FIG. 1, and is a diagram illustrating an example of a strip core according to a second exemplary embodiment of the present invention.

Fig. 4 is a graph illustrating the relationship between the temperature of the strip core and the stacking density ratio of the electrical steel sheets in the block-shaped parts of the test example.

Fig. 5 is a graph illustrating the relationship between the temperature of the strip core and the stacking density ratio of the electrical steel sheets in the block-shaped parts of the test example.

DESCRIPTION OF OPTIONS FOR IMPLEMENTING THE INVENTION

[0011] The following is a detailed description regarding exemplary embodiments of the present invention, with reference to the accompanying drawings. It should be noted that configuration elements having substantially the same functional configuration are given the same reference numerals in this specification and in the drawings, and duplicate explanation thereof will be omitted. Moreover, the proportions and dimensions of each of the configuration elements in the drawings do not represent the actual proportions and dimensions of each of the configuration elements.

[0012] First exemplary embodiment

First, a description will be made regarding the strip core according to the first exemplary embodiment with reference to FIG. 1 and fig. 2. Fig. 1 is a side view illustrating an example of a strip core according to the present exemplary embodiment. Fig. 2 is an enlarged view of part X of FIG. 1 is a diagram illustrating an example of a strip core. It should be noted that in the following, the situation in which the electrical steel sheets S are viewed from the side surface is referred to as a side view. The laying direction of electrical steel sheets S is referred to as "laying direction" where appropriate. Moreover, the sheet width direction of the electrical steel sheets S is referred to as “sheet width direction” where appropriate. In addition, the winding direction of the electrical steel sheets S is referred to as “winding direction” where appropriate.

[0013] The strip core 1 according to the present exemplary embodiment, as illustrated in FIG. 1 is provided with a multilayer body 2 in which a plurality of electrical steel sheets S are laid in a ring shape in a side view (in other words, when the strip core 1 is viewed from the side surface). Namely, the multilayer body 2 is formed by laying a plurality of electrical steel sheets S suitably formed in ring shapes by laying them in the thickness direction of the plate. The multilayer body 2 includes a plurality of curved portions 21, and a plurality of block-shaped portions 22 disposed between adjacent curved portions 21. It should be noted that reference to the side surface of the strip core means the surface formed by the side surfaces of the stacked electrical steel sheets S.

[0014] As illustrated in FIG. 1, in the laminated body 2, the electrical steel sheets S are laid and formed into an octagonal shape in a side view and includes a plurality of curved portions 21 and a plurality of block-shaped portions 22. Specifically, the laminated body 2 is configured by folding and bending the innermost electrical steel sheets S into a rectangular shape to form four inner corner portions 21A. The electrical steel sheet S located at the outer periphery of the innermost electrical steel sheet S is then folded and bent at the inner corner portions 21A of the innermost electrical steel sheet S, and the stacking is thus continued to form two outer corner portions 21B. The curved portions 21 of the multilayer body 2 are portions where a substantially triangular shaped area is formed by connecting straight lines from one inner corner portion 21A to two outer corner portions 21B formed by folding and bending the electrical steel sheets S in this inner corner portion 21A. It should be noted that the present invention is not limited to such a configuration. For example, for two adjacent inner corner portions 21A, the curved portion 21 of the laminate body 2 may be a substantially trapezoidal-shaped region formed by connecting straight lines from the two inner corner portions 21A to the two outer corner portions 21B. Moreover, the block-shaped portions 22 of the laminated body 2 are substantially straight-shaped portions disposed between adjacent curved portions 21. The laminated body 2 of the present exemplary embodiment respectively includes four curved portions 21 and four block-shaped portions 22. As observed on the side surface side of the electrical steel sheet S, the multilayer body 2 is configured at the outer periphery with an octagonal shape including eight outer corner portions 21B. However, at the inner periphery, the multilayer body 2 is configured with a rectangular shape including four inner corner portions 21A.

[0015] Although, for example, known grain-oriented electrical steel sheets or known non-oriented electrical steel sheets can be used in the multilayer body 2, grain-oriented electrical steel sheets are preferably used. The use of grain-oriented electrical steel sheets in the multilayer body 2 allows the loss component of iron loss hysteresis to be reduced, allowing the iron loss of the strip core 1 to be further reduced.

[0016] The thickness of the electrical steel sheets S is not particularly limited, and may be, for example, 0.20 mm or more, and may be 0.40 mm or less. The use of electrical steel S sheets having low thickness (thin sheets) means that eddy currents do not tend to occur in the sheet thickness plane of the electrical steel S sheets, allowing the eddy current loss component of iron losses to be further reduced. As a result, this makes it possible to reduce the iron loss of the strip core 1. The thickness of the electrical steel sheets S is preferably 0.18 mm or more. Moreover, the thickness of the electrical steel sheets S is preferably 0.35 mm or less, and more preferably 0.27 mm or less.

[0017] The stacked electrical steel sheets S are insulated from each other. Preferably, the insulation of the sheets from each other is pre-formed by subjecting the surfaces of the electrical steel sheets S to an insulation treatment. The insulation between layers of S electrical steel sheets means that eddy currents do not tend to occur in the sheet thickness plane in S electrical steel sheets, allowing the eddy current loss component to be reduced. As a result, this makes it possible to further reduce the iron loss of the strip core 1. For example, preferably, the surfaces of the electrical steel sheets S are subjected to insulation treatment using an insulating coating liquid containing colloidal silica and phosphate.

[0018] As illustrated in FIG. 2, the multilayer body 2 is provided with spacer elements 3 in at least a portion between stacked electrical steel sheets S in at least one block-shaped portion 22 among a plurality of block-shaped portions 22. In the block-shaped portion 22 where the spacer elements 3 are inserted , a part of the gap 22A is formed between the sheets of electrical steel S, where the spacer elements 3 are inserted.

[0019] In the multilayer body 2 illustrated in FIG. 2, spacer elements 3 are inserted through each fixed number of stacked electrical steel sheets S, at three locations between the electrical steel sheets S on one of the block-shaped portions 22. This creates portions of the gap 22A between the electrical steel sheets S where the spacer elements 3 are inserted. In cases where the strip core 1 is used when immersed in insulating (transformer) oil, the insulating oil is capable of flowing through parts of the gap 22A. At this time, the gap portion 22A becomes a transfer path for heat generated in the electrical steel sheets S. The heat from the electrical steel sheets S on both sides of the gap portion 22A is transferred to the insulating oil flowing through the gap portion 22A, dissipating the heat generated in the electrical steel sheets S It should be noted that the gap portion 22A is the portion where the gap is created by inserting the spacer members 3 between the electrical steel sheets S, but the size of the gap portion 22A is taken to be the area including both the gap portion and the spacer members 3.

[0020] The laying direction length of the gap portion 22A is preferably 1 mm to 2 mm. The insulating oil flows through the gap portion 22A at a flow rate sufficient to dissipate heat from the electrical steel sheets S if the laying direction length of the gap portion 22A is at least 1 mm. This makes it possible to further suppress the temperature rise in the strip core 1. The laying direction length of the gap portion 22A is more preferably 1.5 mm or more. Moreover, if the laying direction length of the gap portion 22A is not more than 2 mm, the increase in magnetic flux leakage from the electrical steel sheets S into the gap portion 22A (leakage magnetic flux) is largely suppressed, allowing the increase in iron loss to also be suppressed. The laying direction length of the gap portion 22A is more preferably no more than 1.9 mm. It should be noted that the laying direction length of the gap portion 22A can be adjusted by changing the laying direction length of the spacers 3. The laying direction length of the gap portion 22A referred to herein indicates the maximum length of the gap portion 22A along the laying direction of the electrical steel sheet S. The laying direction length of the heat transfer path part of the gap 22A is the thickness of one electrical steel sheet S or more. In other words, the gap thickness of one electrical steel sheet S or more configures the heat transfer path.

[0021] Moreover, the length of the laying direction of the gap portion 22A is preferably substantially constant along the sheet width direction. It should be noted that reference here to "substantially constant" includes laying direction lengths of the gap portion 22A within ±10% of each other. The insulating oil is pumped so as not to be retained in the gap portion 22A due to the laying direction length of the gap portion 22A being substantially constant. This allows the insulating oil to dissipate the heat of the electrical steel sheets S with even greater efficiency and further suppresses the temperature rise in the strip core 1. In order to make the laying direction length of the gap portion 22A substantially constant in the sheet width direction, the sheet width direction length of the spacer members 3 , the position of the spacer elements 3 on the laying surfaces of the electrical steel sheets S or the like can be changed. It should be noted that the length of the sheet width direction of the spacer elements 3 is preferably the same as the length of the sheet width direction for the electrical steel sheets S. In other words, the spacer elements 3 preferably extend along the sheet width direction from one end of the sheet width direction of the electrical steel sheets S to its other end.

[0022] It should be noted that although providing the gap portions 22A in at least one block-shaped portion 22 makes it possible to suppress a temperature rise in the strip core 1, the gap portions 22A are preferably provided in a plurality of block-shaped portions 22. Providing the gap portion 22A in a larger the number of block-shaped pieces 22 increases the contact surface area between the electrical steel sheets S configuring the strip core 1 and the insulating oil, allowing heat to be more effectively dissipated from the electrical steel sheets S. Moreover, providing gap portions 22A in a plurality of block-shaped pieces 22 causes the temperature rise in the strip core 1 to be uniformly suppressed. Thus, portions of the gap 22A are preferably provided in all four block-shaped portions 22. It should be noted that in cases where the lengths of the four block-shaped portions 22 of the laminate body 2 are different from each other ,providing a heat transfer path in the long part in the block shape can,effectively improve the heat dissipation properties. Specifically, as illustrated in FIG. 1, the multilayer body 2 of the present exemplary embodiment includes a pair of opposing long block-shaped portions and a pair of opposing short block-shaped portions, with spacers inserted into at least the long block-shaped portions.

[0023] The stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including portions of the gap 22A is preferably from 86.0% to but not including 91.0%. A stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including the gap portions 22A of 86.0% or more allows iron loss to be maintained low. The stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including the gap portions 22A is more preferably 89.5% or more. Moreover, the stacking density ratio of the electrical steel sheets S of the block-shaped portion 22 including the gap portions 22A is less than 91.0%, which can further suppress the temperature rise in the strip core 1. It should be noted that the stacking density ratio in the block-shaped portion 22 of the multilayer body 2 can be calculated based on JIS C 2550-5:2011. It should be noted that JIS C 2550-5:2011 complies with IEC 60404-13:1995 "Magnetic materials - Part 13: Methods of measurement of density, resistivity and stacking factor of electrical steel sheet and strip".

[0024] Moreover, the portions of the gap 22A are preferably provided such that the distance between the inner peripheral surface of the block-shaped portion 22 and the gap portion 22A, the distance between the outer peripheral surface of the block-shaped portion 22 and the gap portion 22A, and the distance between adjacent portions of the gap 22A essentially the same in the laying direction. This causes the strip core 1 to be cooled more evenly by the insulating oil, suppressing the temperature rise in the strip core 1. In cases where the gap portion 22A is provided in the block-shaped portion 22 by being inserted at one location between the electrical steel sheets S, The gap portion 22A is preferably provided at a position such that the distance between the gap portion 22A and the inner peripheral surface of the block-shaped portion 22 is substantially the same as the distance between the outer peripheral surface of the block-shaped portion 22 and the gap portion 22A.

[0025] The spacer members 3 are inserted between the electrical steel sheets S in a block-shaped portion 22 and form part of the gap 22A. The material used for the spacers 3 is preferably a non-magnetic material. Making the spacer elements 3 from a non-magnetic material makes it possible to prevent the generation of eddy currents in the spacer elements 3 and, as a result, suppresses the increase in iron losses. Specifically, the material of the spacer members 3 is preferably resin, copper, brass and the like. Among these spacer 3 materials, copper is preferred. Copper is a material having high thermal conductivity, and therefore the use of copper for the spacer elements 3 allows the heat from the electrical steel sheets S to be dissipated not only by parts of the gap 22A, but also to be dissipated by the spacer elements 3 themselves.

[0026] Moreover, the spacer members 3 are preferably inserted only into the block-shaped portion 22 of the laminate body 2. In other words, portions of the gap 22A are preferably provided only into the block-shaped portion 22 of the laminate body 2. This is due to the need to take into account that the increase iron losses due to magnetic flux leakage from the gap portion in cases where gap portions are provided in the curved portion 21 will be greater than the increase in heat dissipation surface area. Accordingly, the gap portions 22A are preferably provided in the block-shaped portions 22, where a larger heat dissipation surface area can be ensured than in the curved portions 21.

[0027] The size of the spacer elements 3 is not particularly limited as long as it is possible to form portions of the gap 22A. However, as stated above, the laying direction length of the spacer members 3 is preferably 1 mm to 2 mm, so as to obtain a laying direction length of the gap portions 22A of 1 mm to 2 mm. Moreover, as long as the formed portions of the gap 22A are capable of suppressing the temperature rise of the strip core 1, there is also no particular limitation on the number of spacer members 3 inserted at one location between the electrical steel sheets.

[0028] Moreover, although in FIG. 2, the spacer elements 3 are inserted at three locations between the electrical steel sheets S in one part in the form of a block 22, the number of locations between the electrical steel sheets S where the spacer elements 3 are inserted is not limited to the embodiment shown in FIG. 2, and this amount can be determined in accordance with the size of the strip core 1. However, placing the spacer elements 3 at one and up to three locations between the electrical steel sheets S of at least one block-shaped part 22 among the plurality of block-shaped parts 22 allows greater suppression increasing iron losses while suppressing the temperature rise of the strip core 1. Thus, the spacer members 3 are preferably placed at one and up to three locations between the electrical steel sheets S in at least one block-shaped portion 22 among the plurality of block-shaped portions 22.

[0029] Second exemplary embodiment

Next, a tape core according to the second exemplary embodiment will be described with reference to FIG. 1 and fig. 3. Fig. 3 is an enlarged view of a part corresponding to part X in FIG. 1, and is a diagram illustrating an example of a strip core according to a second exemplary embodiment of the present invention.

[0030] As illustrated in FIG. 1, the strip core 1 according to the present exemplary embodiment includes a laminated body 2 configured with a plurality of electrical steel sheets S arranged in a ring shape in a side view to include a plurality of curved portions 21 and block-shaped portions 22 arranged between adjacent curved portions 21. As illustrated in FIG. 3, the multilayer body 2 includes a heat transfer body 4 at least in part between stacked electrical steel sheets S in at least one block-shaped portion 22 among a plurality of block-shaped portions 22. The strip core 1 according to the present exemplary embodiment differs from the strip core 1 according to the first exemplary embodiment in that the heat transfer body 4 is provided at least in part between stacked electrical steel sheets S in at least one block-shaped portion 22 among a plurality of block-shaped portions 22. Basic configuration of the multilayer body 2 according to the present exemplary embodiment is similar to the configuration of the multilayer body 2 according to the first exemplary embodiment, and therefore a description of the multilayer body 2 will be omitted. Next, the heat transfer body 4 is described in detail.

[0031] As stated above, the heat transfer body 4 is provided at least in part between the stacked electrical steel sheets S in at least one block-shaped portion 22 among a plurality of block-shaped portions 22. In FIG. 3, there are heat transfer bodies 4 present at three locations between the electrical steel sheets S in one of the block-shaped parts 22. Providing a heat transfer body 4 in at least one part between the stacked electrical steel sheets S in at least one block-shaped part 22 among the plurality of block-shaped parts 22 means that the heat generated in the electrical steel sheets S flows through the heat transfer bodies 4, and the heat is dissipated outside the strip core 1. The heat transfer bodies 4 accordingly act as heat transfer paths for the heat generated in the electrical steel sheets S.

[0032] The material used for the heat transfer bodies 4 preferably has high thermal conductivity. Using a material having high thermal conductivity as a material for the heat transfer bodies 4 ensures more efficient dissipation of heat generated in the electrical steel sheets S. This makes it possible to suppress the temperature rise in the strip core 1. Moreover, the material of the heat transfer body 4 is preferably a material that is non-magnetic material and insulator.

Using a material that is a non-magnetic material and has insulating properties as the material of the heat transfer bodies 4 makes it possible to prevent the generation of eddy currents in the heat transfer bodies 4. As a result, it ensures that the increase in iron losses is suppressed. Specifically, the material of the heat transfer bodies 4 is preferably phenolic (Bakelite). Phenolic plastic has high thermal conductivity and is a non-magnetic material and insulator. Thus, the temperature rise in the strip core 1 can be suppressed by effectively dissipating the heat generated in the electrical steel sheets S, ensuring that the increase in iron loss is suppressed by preventing the generation of eddy currents in the heat transfer bodies 4. More specifically, the heat transfer bodies 4 are preferably configured to include a paper-based phenolic layer, a fabric-based phenolic layer (textolite), or a fiberglass-based phenolic layer (fiberglass).

[0033] It should be noted that although the shape of the heat transfer bodies 4 is not particularly limited, preferably the heat transfer bodies 4 are formed to be inserted widely (at a wide interval) between the electrical steel sheets S of the block-shaped part 22. By inserting the heat transfer bodies 4 widely between the sheets electrical steel S portion in the form of a block 22, the contact surface area between the electrical steel sheets S and the heat transfer bodies 4 is increased, allowing heat to be more effectively dissipated from the electrical steel sheets S and suppressing the temperature rise in the strip core 1.

[0034] It should be noted that although the heat transfer bodies 4 are capable of suppressing a temperature rise in the strip core 1 by being provided in at least one part in the form of a block 22, the heat transfer bodies 4 are preferably provided in a plurality of parts in the form of a block 22. Providing the bodies 4 transferring heat into more parts in the form of a block 22 increases the contact surface area between the insulating oil and the electrical steel sheets S configuring the strip core 1, and the heat from the electrical steel sheets S effectively flows into the insulating oil through the heat transfer bodies 4. Namely, heat dissipation from the electrical steel sheets S is achieved more efficiently. Moreover, providing the heat transfer bodies 4 in a plurality of parts in the form of a block 22 uniformly suppresses the temperature rise in the strip core 1. The heat transfer bodies 4 are accordingly preferably provided in up to four parts in the shape block 22.

[0035] The stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including the heat transfer bodies 4 is preferably from 86.0% to, but not including, 91.0%. A stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including the heat transfer body 4 of 86.0% or more can keep iron losses low. The stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including the heat transfer bodies 4 is preferably 89.5% or more. Moreover, the stacking density ratio of the electrical steel sheets S in the block-shaped portion 22 including the heat transfer bodies 4 is less than 91.0%, which further suppresses the temperature rise in the strip core 1. It should be noted that although the density ratio stacking can be calculated based on JIS C 2550-5:2011, in the present exemplary embodiment, the stacking density coefficient is calculated without taking into account the mass of the heat transfer bodies 4.

[0036] Moreover, the heat transfer bodies 4 are preferably provided so that there are substantially equal distances in the laying direction for the distance between the inner peripheral surface of the block-shaped part 22 and the heat transfer body 4, the distance between the outer peripheral surface of the block-shaped part 22 and the body 4 heat transfers and distances between adjacent bodies 4 heat transfers. This causes the strip core 1 to be more uniformly cooled by the insulating oil through the heat transfer bodies 4, suppressing the temperature rise in the strip core 1. In cases where the heat transfer body 4 is provided at one location between the electrical steel sheets in the block-shaped portion 22, the body The heat transfer body 4 is preferably provided in a position such that the distance between the inner peripheral surface of the block-shaped portion 22 and the heat transfer body 4 is substantially the same as the distance between the outer peripheral surface of the block-shaped portion 22 and the heat transfer body 4 .

[0037] Although in FIG. 3, the heat transfer bodies 4 are arranged at three locations between the electrical steel sheets S in one of the block-shaped portions 22, the number of locations between the electrical steel sheets S where the heat transfer bodies 4 are inserted is not limited to those shown in FIG. 3, and their number can be determined in accordance with the size of the strip core 1. However, the insertion of heat transfer bodies 4 at one and up to three locations between the electrical steel sheets S in at least one block-shaped part 22 among a plurality of block-shaped parts 22 allows further suppress the increase in iron losses while suppressing the temperature rise in the strip core 1. The heat transfer bodies 4 are preferably inserted at one and up to three locations between the electrical steel sheets S in at least one block-shaped portion 22 among the plurality of block-shaped portions 22.

[0038] Modified Examples

The following describes a number of modified examples of the exemplary embodiments of the present invention described above. It should be noted that each of the modified examples described above can be applied separately from the exemplary embodiments of the present invention described above, or the modified examples described below can be combined and applied to the exemplary embodiments of the present invention described above. Moreover, each of the modified examples may be used in place of the configuration in the exemplary embodiments of the present invention described above, or may be used in addition to the configuration of the exemplary embodiments of the present invention described above.

[0039] Moreover, although in the exemplary embodiments described above, cases have been described in which the outer periphery of the multilayer body has an octagonal shape, the present invention is not limited to this. The outer periphery of the multilayer body may have a polygonal shape, a square shape with rounded corners, an oval shape, an elliptical shape, or the like. For example, an oval-shaped multilayer body can be produced by winding a strip of electrical steel. On the other hand, the octagonal-shaped multilayer body can be made from a plurality of electrical steel sheets folded and bent into a ring shape and laid in the thickness direction of the sheet. A multilayer body produced by laying a plurality of electrical steel sheets folded and bent into a ring shape by laying in the thickness direction of the sheet results in a stacking density ratio in the bent portions that is likely to be less than that of a multilayer body manufactured by winding an electrical steel strip. become. Therefore, the packing density ratio of at least one curved portion 21 among the plurality of curved portions 21 of the multilayer body 2 can be increased. Specifically, the gaps between the electrical steel sheets S in the bent portion 21 can be reduced by compressing the bent portion 21 from the inner peripheral side and the outer peripheral side using a compression means. This makes it possible to achieve a higher packing density ratio in the curved portion 21, allowing the interference reduction effect in the multilayer body 2 to be achieved.

[0040] In the exemplary embodiments described above, cases have been described in which the inner periphery of the multilayer body has a tetrahedral shape, but the present invention is not limited to this. The inner periphery of the multilayer body may have another polygonal shape, a square shape with rounded corners, an oval shape, an elliptical shape, and the like. For example, in cases where the inner periphery of the multilayer body has an octagonal shape, the portion connecting two adjacent vertices of the octagonal shape is the inner corner portion, and in cases where the inner periphery of the multilayer body has an oval shape, the arcuate portions are the inner corner portions. In cases where the inner periphery of the multilayer body has a polygonal shape, a square rounded shape, an oval shape, an elliptical shape or the like, the curved parts are parts at positions between one adjacent block-shaped part and another adjacent block-shaped part, where the sheets electrical steel sheets S are bent with respect to the direction of extension of electrical steel sheets S in one part in the form of a block and sheets of electrical steel S in another part in the form of a block and laid.

[0041] Moreover, the inner periphery of the multilayer body can be formed in accordance with the shape of its outer periphery. For example, in cases where the outer periphery of the multilayer body has an octagonal shape, the inner periphery may also have an octagonal shape, and in cases where the outer periphery of the multilayer body has a square shape with rounded corners, the inner periphery can also have a square shape with rounded corners.

[0042] The heat transfer paths (parts of the gaps 22A, heat transfer bodies 4) illustrated in FIG. 2 and fig. 3 are examples only, and are obviously not limited to the modes described above. For example, the recessed portion can be formed by subjecting the portion configuring the block-shaped portion 22 of one of the electrical steel sheets S among the superimposed electrical steel sheets S to folding and bending processing to form a gap portion on the inner side of the recessed portion.

[0043] Many exemplary embodiments in accordance with the present invention have been described above. The strip core according to these exemplary embodiments is provided with a multilayer body including a plurality of electrical steel sheets arranged in a ring shape in a side view, a plurality of curved portions, and block-shaped portions at positions between adjacent curved portions. The at least one block-shaped portion among the plurality of block-shaped portions includes a heat transfer path defined by the electrical steel sheets in at least a portion between the stacked electrical steel sheets. The heat generated by the electrical steel sheets when an alternating magnetic field is applied is dissipated with high efficiency through the heat transfer path, suppressing the temperature rise in the strip core. By providing a heat transfer path at least in part between the stacked electrical steel sheets in the block-shaped part, leakage of magnetic flux from the electrical steel sheets into the heat transfer path is small, and low iron losses are maintained.

[0044] The strip core according to the present exemplary embodiment is applicable to a transformer (not shown in the drawings). The transformer according to the present exemplary embodiment is provided with a strip core 1 according to the present exemplary embodiment, a primary winding and a secondary winding. A magnetic field is generated in the strip core 1 by applying an alternating current voltage to the primary winding, and a voltage is induced in the secondary winding due to fluctuations in the generated magnetic field. Such a strip core includes a heat transfer path at least in part between stacked electrical steel sheets in at least one block-shaped part among a plurality of block-shaped parts, and therefore heat generated in the strip core is dissipated through the heat transfer path. As a result, low iron losses are maintained while temperature rise is suppressed.

[0045] Next, test examples of the present invention are described. The example conditions of the present test example are an example of conditions adopted to confirm the feasibility and useful results of the present invention, and the present invention is not limited to these example conditions. The present invention may take on various conditions to achieve the object of the present invention without deviating from the spirit of the present invention.

[0046] Test Case 1

A multilayer body having a substantially octagonal shape including four curved parts and four block-shaped parts was manufactured by laying grain-oriented electrical steel sheets having a thickness of 0.23 mm. The length of the laminate body in the laying direction was 20 mm, and strip cores were manufactured with the following conditions, including a number of gap parts listed in Table 1 for each of the four block-shaped parts. Spacer elements made of phenolic (Bakelite) were inserted between sheets of electrical steel S in each of the four parts in the form of a sandwich body block to provide gap parts. The gap parts are provided so that there are equivalent distances in the laying direction for the distance between the inner peripheral surface of the block-shaped part and the gap part, the distance between the outer peripheral surface of the block-shaped part and the gap part, and the distance between adjacent gap parts. In transformer No. 2, the gap portion is provided at a position such that the distance between the inner peripheral surface of the block-shaped portion and the gap portion and the distance between the outer peripheral surface of the block-shaped portion and the gap portion are substantially the same distance. For the gap parts, the stacking direction length was 1 mm, the sheet width direction length was 300 mm, and the winding direction length was 100 mm. The winding wires were wound around these strip cores, the strip cores were installed in a tank, the tank was filled with insulating oil to make transformers with a capacity of 20 kVA.

[0047] The stacking density coefficient of electrical steel sheets in a block-shaped part was calculated for strip cores based on JIS C 2550-5:2011. Moreover, iron losses (no-load losses) were measured for transformers based on JEC-2200. The temperature of the strip cores was measured after operating the manufactured transformers for 12 hours. Table 1 lists the number of gap parts per block shape, packing density factor, temperature, iron loss, proportional increase in iron loss. Fig. 4 illustrates the relationship between the stacking density ratio of electrical steel sheets in a block-shaped part and the temperature of the strip core. It should be noted that the stacking density coefficient in Table 1 is the average value of the stacking density coefficients for electrical steel sheets in four parts in block form.

[0048] The manufactured transformer was evaluated using the following criteria. The result of the rating "A (excellent)" was given in cases in which the temperature of the transformer fell relative to the base temperature level of transformer No. 1, which was not provided with gap parts, and the proportional increase in iron losses was less than 10%, relative to the base level of iron losses transformer No. 1. A "B (Good)" rating result was given in cases in which the transformer temperature did not fall below the baseline temperature of Transformer No. 1, or in cases in which the proportional increase in iron loss was 10% or more relative to the baseline iron loss level of Transformer No. 1.

1. It should be noted that the evaluation result of A is better than B. It should be noted that the examples in Table 1 indicate examples of implementations applying the present invention, and the comparative examples indicate examples of implementations not applying the present invention.

[0050] Increasing the number of gap parts provided in the block-shaped part increased the contact surface area between the strip core and the insulating oil, and the temperature of the strip cores dropped. Moreover, as illustrated in FIG. 4, the temperature of the strip core dropped as the stacking density ratio decreased. The temperature rise was significantly suppressed in transformer No. 4. Although transformer No. 5 suppressed the temperature rise, the proportional increase in iron losses exceeded 10%.

[0051] Test case 2

Tape cores were manufactured in a manner similar to that in Test Example 1 using grain-oriented electrical steel sheets having a thickness of 0.20 mm, and transformers with a capacity of 1 kVA were manufactured using the fabricated strip cores. The length of the laminate body in the laying direction was 20 mm, and strip cores including gap portions in the number listed in Table 2 in each of the four block-shaped portions were manufactured in accordance with the following conditions. For the gap parts, the stacking direction length was 1 mm, the sheet width direction length was 200 mm, and the winding direction length was 70 mm. For the manufactured transformers, the stacking density ratio of electrical steel sheets in block-shaped parts, strip core temperature and iron loss (no-load loss) were measured similar to Test Case 1. Table 2 lists the number of gap parts per block-shaped part, coefficient packing density, temperature, iron losses and proportional increase in iron losses. Moreover, FIG. 5 illustrates the relationship between the packing density ratio of electrical steel sheets in block-shaped parts and the temperature of the strip core. It should be noted that the stacking density coefficient in Table 2 is the average value of the stacking density coefficients for electrical steel sheets in four parts in block form. The evaluation of the transformers was performed with criteria similar to those for Test Example 1. It should be noted that the examples in Table 2 indicate examples of implementations applying the present invention, and the comparative examples indicate examples of implementations not applying the present invention.

[0053] Increasing the number of gap portions provided in the block-shaped portion increased the contact surface area between the tape core and the insulating oil, and the temperature of the core tape dropped. Moreover, as illustrated in FIG. 4, the temperature of the strip core dropped as the stacking density ratio decreased. The temperature rise was significantly suppressed in transformer No. 4. In transformer No. 5, although the temperature rise was suppressed, the proportional increase in iron losses exceeded 10%.

[0054] Test Case 3

A substantially octagonal-shaped multi-layer body including four curved parts and four block-shaped parts was manufactured by laying grain-oriented electrical steel sheets having a thickness of 0.23 mm. The length of the multilayer body in the laying direction was 20 mm, and strip cores including heat transfer bodies were manufactured with the following conditions listed in Table 3 for one block-shaped part among four block-shaped parts. Spacers made of bakelite were inserted between electrical steel sheets in one block-shaped part in a sandwich body to provide gap parts. The gap portions were provided such that there were equivalent distances in the laying direction for the distance between the inner peripheral surface of the block-shaped portion and the gap portion, the distance between the outer peripheral surface of the block-shaped portion and the gap portion, and the distance between adjacent gap portions. In Transformer No. 2, the gap portion was provided at a position such that the distance between the inner peripheral surface of the block-shaped portion and the gap portion was substantially the same as the distance between the outer peripheral surface of the block-shaped portion and the gap portion. For the gap parts, the stacking direction length was 1 mm, the sheet width direction length was 150 mm, and the winding direction length was 100 mm. Winding wires were wound on these strip cores, the strip cores were installed in a tank, and the tank was filled with insulating oil to produce transformers with a capacity of 10 kVA. For the manufactured transformers, the packing density ratio of electrical steel sheets into a block-shaped portion including gap portions, strip core temperature, and iron loss (no-load loss) were measured in a manner similar to that of Test Example 1. Number of gap portions, density ratio laying, temperature, iron loss and proportional increase in iron loss in the block-shaped part including the gap parts are listed in Table 3. It should be noted that the laying density coefficient in Table 3 is the laying density coefficient for electrical steel sheets in the part in the form of a block including gap parts. The evaluation of the transformer was performed using criteria similar to those in Test Example 1. It should be noted that the examples in Table 3 indicate examples of implementations applying the present invention, and the comparative examples indicate examples of implementations not applying the present invention.

[0056] The present invention maintains low iron losses and suppresses temperature rise.

[0057] Detailed explanation has been given regarding the preferred exemplary embodiments and examples of the present invention with reference to the accompanying drawings, however, the present invention is not limited to these examples. Various modifications and improvements in the range of technological principles set forth within the scope of the claims will be apparent to one skilled in the technological field of the present invention, and it is obvious that these modifications and improvements should also be understood as falling within the technical scope of the present invention.

[0058] The invention is now set forth in the following additions to the above exemplary embodiments.

[0059] Addendum 1

A strip core provided with a multilayer body including a plurality of electrical steel sheets arranged in a ring shape in a side view, wherein:

the multilayer body includes a plurality of curved portions and a plurality of block-shaped portions at positions between adjacent curved portions;

at least one block-shaped portion among the plurality of block-shaped portions includes a heat transfer path defined by the electrical steel sheets in at least a portion between the stacked electrical steel sheets; And

the heat transfer path is included only in the at least one block-shaped portion.

[0060] Addendum 2

The strip core of Addendum 1, wherein the stacking density ratio of the electrical steel sheets in the at least one block-shaped portion containing the heat transfer path is from 86.0% to, but not including, 91.0%.

[0061] Addendum 3

Tape core of Addition 1 or Addendum 2, where the heat transfer path length in the laying direction of the electrical steel sheets is from 1 mm to 2 mm.

[0062] Addendum 4

The strip core according to any one of Appendix 1 to Appendix 3, wherein the heat transfer path is located at one and up to three locations between the electrical steel sheets in at least one block-shaped part among the plurality of block-shaped parts.

[0063] Addendum 5

Tape core according to any one of Appendix 1 to Appendix 4, additionally including:

a spacer element in at least one part between stacked electrical steel sheets in at least one block-shaped part among a plurality of block-shaped parts,

wherein the part of the gap formed between the electrical steel sheets by means of the spacer element represents a heat transfer path.

[0064] Addendum 6

The tape core of Addendum 5, wherein the spacer element is made of a non-magnetic material.

[0065] Addendum 7

The strip core according to any one of Appendix 1 to Appendix 4, wherein the heat transfer path is formed by a heat transfer body having non-magnetic properties and insulating properties.

[0066] Addendum 8

Tape core Addendum 7, with the heat transfer path formed by phenolic plastic.

[0067] Addendum 9

The strip core according to any one of Appendix 1 to Appendix 8, wherein a heat transfer path is provided for all parts in the form of a block.

[0068] Addendum 10

Tape core according to any one of Appendix 1 to Appendix 8, and:

the at least one block-shaped portion includes a first block-shaped portion and a second block-shaped portion longer than the first block-shaped portion; And

The heat transfer path is only included in the second block-shaped part.

[0069] Addendum 11

Tape core according to any one of Appendix 1 to Appendix 10, and:

the shape of the multilayer body in the side view is an octagonal shape, including four block-shaped parts and four curved parts.

[0070] Addendum 12

Tape core including:

a multilayer body including a plurality of electrical steel sheets arranged in a ring shape in a side view, a plurality of curved portions, and block-shaped portions at positions between adjacent curved portions; And

at least one block-shaped portion among the plurality of block-shaped portions includes a heat transfer path defined by the electrical steel sheets in at least a portion between the stacked electrical steel sheets.

[0071] Addendum 13

The strip core of Addendum 12, wherein the stacking density ratio of the electrical steel sheets in the block-shaped portion containing the heat transfer path is from 86.0% to, but not including, 91.0%.

[0072] Addendum 14

Tape core Supplement 12 or Supplement 13, where the heat transfer path length in the laying direction of the electrical steel sheets is from 1 mm to 2 mm.

[0073] Addendum 15

The strip core according to any one of Appendix 12 to Appendix 14, wherein the heat transfer path is located at one and up to three locations between the electrical steel sheets in at least one block-shaped part among the plurality of block-shaped parts.

[0074] Addendum 16

Tape core according to any one of Appendix 12 to Appendix 15, additionally including:

a spacer element in at least one part between stacked electrical steel sheets in at least one block-shaped part among a plurality of block-shaped parts,

wherein the part of the gap formed between the electrical steel sheets by means of the spacer element represents a heat transfer path.

[0075] Addendum 17

The tape core of Addendum 16, wherein the spacer element is made of a non-magnetic material.

[0076] Addendum 18

The strip core according to any one of Appendix 12 to Appendix 15, wherein the heat transfer path is formed by a heat transfer body having non-magnetic properties and insulating properties.

[0077] Addendum 19

Tape core Addition 18, with the heat transfer path formed by phenolic plastic.

[0078] Addendum 20

The strip core according to any one of Appendix 12 to Appendix 19, wherein the shape of the multi-layer body when viewed from the side is an octagonal shape.

[0079] It should be noted that the entire contents of Japanese Patent Application No. 2019-160544, filed on September 3, 2019, are incorporated by reference into this specification.

All publications, patent applications and technical standards mentioned herein are incorporated by reference into this specification to the same extent as if each individual publication, patent application or technical standard were specifically and separately identified as being incorporated by reference.

Claims (30)

1. A strip core comprising a multilayer body including a plurality of electrical steel sheets arranged in a ring shape in a side view, wherein: the multilayer body includes a plurality of curved portions and a plurality of block-shaped portions at positions between adjacent curved portions; at least one block-shaped portion among the plurality of block-shaped portions includes a heat transfer path defined by the electrical steel sheets in at least a portion between the stacked electrical steel sheets; the heat transfer path is included only in the at least one block-shaped portion; wherein the spacer is provided in at least one portion between the stacked electrical steel sheets in the at least one block-shaped portion among the plurality of block-shaped portions, and the gap portion formed between the electrical steel sheets by the spacer is a heat transfer path, and the spacer is made of a non-magnetic material. 2. The strip core according to claim 1, wherein the stacking density ratio of the electrical steel sheets in at least one block-shaped portion containing the heat transfer path is from 86.0% to, but not including, 91.0%. 3. Strip core according to claim 1 or 2, in which the length of the heat transfer path in the direction of laying the electrical steel sheets is from 1 to 2 mm. 4. Tape core according to any one of paragraphs. 1-3, wherein the heat transfer path is located at one and up to three locations between sheets of electrical steel in at least one block-shaped part among a plurality of block-shaped parts. 5. A strip core comprising a multilayer body including a plurality of electrical steel sheets arranged in a ring shape in a side view, wherein: the multilayer body includes a plurality of curved portions and a plurality of block-shaped portions at positions between adjacent curved portions; at least one block-shaped portion among the plurality of block-shaped portions includes a heat transfer path defined by the electrical steel sheets in at least a portion between the stacked electrical steel sheets; the heat transfer path is included only in the at least one block-shaped portion; wherein the heat transfer path is formed by a heat transfer body formed by a phenolic material having non-magnetic properties and insulating properties. 6. A strip core comprising a multilayer body including a plurality of electrical steel sheets arranged in a ring shape in a side view, wherein: the multilayer body includes a plurality of curved portions and a plurality of block-shaped portions at positions between adjacent curved portions; all block-shaped parts include a heat transfer path defined by the electrical steel sheets in at least a portion between the stacked electrical steel sheets. 7. Tape core according to any one of paragraphs. 1-5, in which: the at least one block-shaped portion includes a first block-shaped portion and a second block-shaped portion longer than the first block-shaped portion; And The heat transfer path is only included in the second block-shaped part. 8. Tape core according to any one of paragraphs. 1 to 7, in which the shape of the multilayer body in a side view is an octagonal shape including four block-shaped portions and four curved portions. 9. The strip core according to claim 6, wherein the stacking density ratio of the electrical steel sheets in all block-shaped parts containing the heat transfer path is from 86.0% to, but not including, 91.0%. 10. Strip core according to claim 6 or 9, in which the length of the heat transfer path in the direction of laying the electrical steel sheets is from 1 to 2 mm. 11. Tape core according to any one of paragraphs. 6, 9 or 10, in which the heat transfer path is located at one and up to three locations between the electrical steel sheets in all parts in the form of a block. 12. Tape core according to any one of paragraphs. 6, 9-11, additionally containing: a spacer element in at least one part between stacked electrical steel sheets in all parts in the form of a block, wherein the part of the gap formed between the electrical steel sheets by means of the spacer element represents a heat transfer path. 13. Band core according to claim 12, in which the spacer element is made of non-magnetic material. 14. Tape core according to any one of paragraphs. 6, 9-11, in which the heat transfer path is formed by a heat transfer body having non-magnetic properties and insulating properties. 15. The tape core according to claim 14, in which the heat transfer path is formed by phenolic plastic.