Wound core

Abstract

The present invention provides a wound iron core, comprising a stacked body formed by stacking a plurality of electromagnetic steel plates in a ring shape in a side view, the stacked body having a plurality of bent portions and a plurality of side portions located between adjacent bent portions, at least one of the plurality of side portions having a heat transfer path facing the electromagnetic steel plates in at least a portion between the stacked electromagnetic steel plates, and the heat transfer path is only located at the side portion.

Description

Technical Field

[0001] The invention relates to a wound core. Background Art

[0002] The wound core is used as a magnetic core of a transformer, a reactor, a noise filter, etc. In the transformer, reducing the iron loss has been one of the important issues from the viewpoint of increasing efficiency, and research on reducing the iron loss has been conducted from various viewpoints.

[0003] For example, Japanese Patent Gazette No. 2017-84889 discloses a low-noise wound transformer, in which a circumferential band is wound along the winding direction of the steel plate on the outer periphery of an iron core composed of steel plates wound in a coil shape, and a stacking direction band with a vibration loss coefficient η>0.01 is arranged on the surface side of the circumferential band between the winding wound on the iron core and the iron core.

[0004] In addition, for example, Japanese Patent Gazette No. 2018-148036 discloses a wound core having a wound core body that is roughly rectangular in side view. The wound core body of the wound core is a directional electromagnetic steel sheet in which a flat portion and a corner portion are alternately continuous in the length direction and the angle formed by two flat portions adjacent to each corner portion is 90°, including a portion stacked in the plate thickness direction, and has a roughly rectangular stacking structure in side view. Furthermore, in the side view of the directional electromagnetic steel sheet, each corner portion has two or more curved portions having a curved shape, and the total of the bending angles of each curved portion present in one corner portion is 90°. In addition, the inner surface side curvature radius r of the curved portion in side view exceeds 1 mm and is less than 3 mm. Furthermore, on the surface of the steel sheet surface on the inner surface side and the outer surface side of the grain-oriented electromagnetic steel sheet and having a 180° magnetic domain wall parallel to the length direction, there is an area where reflux magnetic domains with a length direction size of 150 μm or less and a thickness direction size of 30 μm or more exist continuously and linearly in the width direction at intervals of 0.5 mm or more and 8 mm or less in the length direction. And the area where the reflux magnetic domains exist occupies more than 25% of the surface area of ​​the steel sheet surface on the inner surface side or the outer surface side. Summary of the invention

[0005] Problems to be solved by the invention

[0006] However, transformers using wound cores are widely used in electrical and electronic equipment, but due to the heat generated by iron loss, the insulating paper arranged between the wound core and the winding wound on the wound core may be heated and deteriorated. The insulating paper may break due to deterioration, and the transformer with broken insulating paper may cause insulation failure. In order to prevent the deterioration of the insulating paper, the temperature of the wound core needs to be maintained as low as possible. In order to suppress the temperature rise of the wound core, a general transformer stores the wound core in insulating oil (insulating oil) and dissipates the heat generated by the wound core by retaining the insulating oil. However, the insulating oil that helps to dissipate heat is in contact with the wound core only on the surface of the wound core. Therefore, heat dissipation based on the insulating oil is only performed from the surface of the wound core, and when the heat generated by the wound core is large, the heat dissipation effect is sometimes insufficient.

[0007] An object of the present invention is to provide a wound core capable of maintaining low iron loss and suppressing temperature rise.

[0008] Means for solving problems

[0009] The inventors of the present invention have obtained the following insights during the process of intensive research on suppressing the temperature rise of the wound core: In order to increase the amount of heat dissipated from the wound core, it is important to increase the heat dissipation area in the wound core. And, they thought of dissipating heat from between the stacked electromagnetic steel plates. On the other hand, when the interval between the stacked electromagnetic steel plates is excessively expanded, there is a tendency for the iron loss to increase. The inventors of the present invention have further studied a wound core that can maintain a low iron loss and suppress the temperature rise of the wound core, and as a result, completed the present invention.

[0010] The gist of one embodiment of the present invention completed based on the above findings is as follows.

[0011] A wound core according to one embodiment of the present invention comprises a stacked body formed by stacking a plurality of electromagnetic steel sheets in a ring shape in a side view, the stacked body having a plurality of bent portions and a plurality of side portions located between adjacent bent portions, at least one of the plurality of side portions having a heat transfer path facing the electromagnetic steel sheets in at least a portion between the stacked electromagnetic steel sheets, and the heat transfer path exists only in the edge portions.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide a wound core capable of maintaining low iron loss and suppressing a temperature increase. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side view showing an example of a wound core according to the first embodiment of the present invention.

[0015] Figure 2is a diagram showing an example of a wound core according to the first embodiment, and is Figure 1 Magnified view of the X section.

[0016] Figure 3 is a diagram showing an example of a wound core according to a second embodiment of the present invention, and is Figure 1 The X portion corresponds to an enlarged view of the portion.

[0017] Figure 4 This is a graph showing the relationship between the filling factor of the electromagnetic steel sheet in the side portion and the temperature of the winding core in the test example.

[0018] Figure 5 This is a graph showing the relationship between the filling factor of the electromagnetic steel sheet in the side portion and the temperature of the winding core in the test example. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail with reference to the accompanying drawings. In addition, in this specification and the drawings, the same symbols are marked on the components having substantially the same functional configuration, thereby omitting a general repetitive description. In addition, the proportions and sizes of the components in the drawings do not represent the actual proportions and sizes of the components.

[0020] <First Embodiment>

[0021] First, refer to Figure 1 as well as Figure 2 The wound core according to the first embodiment will be described. Figure 1 It is a side view showing an example of the wound core according to the present embodiment. Figure 2 is a diagram showing an example of a wound core, and is Figure 1 An enlarged view of the X portion. In addition, hereinafter, the case where the electromagnetic steel sheet S is viewed from the side is referred to as a side view. The stacking direction of the electromagnetic steel sheet S is appropriately referred to as the "stacking direction". In addition, the plate width direction of the electromagnetic steel sheet S is appropriately referred to as the "plate width direction". Furthermore, the winding direction of the electromagnetic steel sheet S is appropriately referred to as the "winding direction".

[0022] like Figure 1 As shown in FIG. 1 , the wound core 1 of the present embodiment includes a laminate 2 in which a plurality of electromagnetic steel sheets S are laminated in a ring shape in a side view (in other words, the wound core 1 is viewed from the side). In other words, a plurality of electromagnetic steel sheets S formed in a ring shape are laminated in the plate thickness direction to form the laminate 2. The laminate 2 has a plurality of bent portions 21 and a plurality of side portions 22 located between the mutually adjacent bent portions 21. In addition, the side surface of the wound core referred to here refers to a surface formed by the side surfaces of the laminated electromagnetic steel sheets S.

[0023] like Figure 1As shown, the laminate 2 is formed into an octagon in a side view by laminating electromagnetic steel sheets S, and has a plurality of bent portions 21 and a plurality of side portions 22. Specifically, the laminate 2 is laminated in the following manner: the innermost electromagnetic steel sheet S is bent in a manner to form four corners 21A to form a rectangular shape, and the electromagnetic steel sheets S located on the outer periphery of the innermost electromagnetic steel sheet S are laminated in a manner to form two corners 21B by bending at the corner 21A of the innermost electromagnetic steel sheet S. Here, the bent portion 21 of the laminate 2 is a portion of a roughly triangular region formed by connecting one corner 21A and two corners 21B formed by bending the electromagnetic steel sheet S at the corner 21A with a straight line. In addition, the present invention is not limited to this configuration. For example, in the case where there are two corners 21A adjacent to each other, the bent portion 21 of the laminate 2 may also be a portion of a roughly trapezoidal region formed by connecting the two corners 21A and the two corners 21B with straight lines, respectively. In addition, the side portion 22 of the laminated body 2 is a substantially straight portion located between adjacent curved portions 21. In this way, the laminated body 2 of the present embodiment has four curved portions 21 and four side portions 22. Furthermore, when viewed from the side surface of the electromagnetic steel sheet S, the laminated body 2 is formed into an octagon having eight corners 21B on the outer periphery. On the other hand, the laminated body 2 is formed into a rectangle having four corners 21A on the inner periphery.

[0024] The laminate 2 may be made of conventional grain-oriented electromagnetic steel sheets or conventional non-oriented electromagnetic steel sheets, but is preferably made of grain-oriented electromagnetic steel sheets. By using grain-oriented electromagnetic steel sheets in the laminate 2, hysteresis loss in iron loss can be reduced, and iron loss of the wound core 1 can be further reduced.

[0025] The thickness of the electromagnetic steel sheet S is not particularly limited, and can be, for example, 0.20 mm or more, or 0.40 mm or less. By using an electromagnetic steel sheet S with a relatively small (thin) thickness, it is difficult to generate eddy currents in the thickness plane of the electromagnetic steel sheet S, and the eddy current loss in the iron loss can be further reduced. As a result, the iron loss of the wound core 1 can be reduced. The thickness of the electromagnetic steel sheet S is preferably 0.18 mm or more. In addition, the thickness of the electromagnetic steel sheet S is preferably 0.35 mm or less, and more preferably 0.27 mm or less.

[0026] The stacked electromagnetic steel sheets S are insulated from each other. It is preferred that the surfaces of the electromagnetic steel sheets S be insulated from each other by performing an insulation treatment. By insulating the interlayers of the electromagnetic steel sheets S, it is difficult for eddy currents to be generated in the plate thickness plane of the electromagnetic steel sheets S, and eddy current losses can be reduced. As a result, the iron loss of the wound core 1 can be further reduced. For example, it is preferred that the surfaces of the electromagnetic steel sheets S be insulated using an insulating coating liquid containing colloidal silica and phosphate.

[0027] like Figure 2As shown, the laminate 2 includes a spacer 3 at least partially between the stacked electromagnetic steel sheets S in at least one side 22 of the plurality of sides 22. In the side 22 where the spacer 3 is interposed, a gap portion 22A is formed between the electromagnetic steel sheets S interposed with the spacer 3.

[0028] exist Figure 2 In the laminated body 2 shown, a spacer 3 is sandwiched between the electromagnetic steel sheets S at three locations in one side portion 22, at intervals of a certain number of stacked electromagnetic steel sheets S. Thus, a gap portion 22A is formed between the electromagnetic steel sheets S sandwiched with the spacer 3. When the wound core 1 is immersed in insulating oil for use, the insulating oil can flow in the gap portion 22A. Thus, the gap portion 22A becomes a heat transfer path for the heat generated by the electromagnetic steel sheets S. Then, heat is transferred from the electromagnetic steel sheets S on both sides of the gap portion 22A to the insulating oil flowing in the gap portion 22A, and the heat generated by the electromagnetic steel sheets S is dissipated. In addition, the gap portion 22A refers to a gap portion generated by sandwiching the electromagnetic steel sheets S with the spacer 3, but the size of the gap portion 22A refers to a region including the gap portion and the spacer 3.

[0029] The length of the gap portion 22A in the stacking direction is preferably 1 mm or more and 2 mm or less. If the length of the gap portion 22A in the stacking direction is 1 mm or more, the insulating oil flows in the gap portion 22A at a flow rate sufficient to dissipate the heat of the electromagnetic steel sheet S. Thus, the temperature rise of the wound core 1 can be further suppressed. The length of the gap portion 22A in the stacking direction is more preferably 1.5 mm or more. In addition, if the length of the gap portion 22A in the stacking direction is 2 mm or less, the increase in the magnetic flux (leakage magnetic flux) leaking from the electromagnetic steel sheet S to the gap portion 22A can be suppressed, and the increase in iron loss can be suppressed. The length of the gap portion 22A in the stacking direction is more preferably 1.9 mm or less. In addition, by changing the length of the spacer 3 in the stacking direction, the length of the gap portion 22A in the stacking direction can be adjusted. In addition, the length of the gap portion 22A in the stacking direction mentioned here refers to the maximum length of the gap portion 22A along the stacking direction of the electromagnetic steel sheet S. And the length of the gap portion 22A in the stacking direction as a heat transfer path is greater than the thickness of one electromagnetic steel sheet S. In other words, a gap greater than or equal to the thickness of one electromagnetic steel sheet S is used as a heat transfer path.

[0030] In addition, the stacking direction length of the gap portion 22A is preferably approximately constant in the plate width direction. In addition, the approximately constant mentioned here includes the stacking direction length of the gap portion 22A ±10%. By making the stacking direction length of the gap portion 22A approximately constant, it is possible to suppress the insulating oil from being retained in the gap portion 22A. As a result, the insulating oil can dissipate the heat of the electromagnetic steel sheet S more efficiently, and the temperature rise of the wound core 1 can be further suppressed. In order to make the stacking direction length of the gap portion 22A approximately constant in the plate width direction, it is sufficient to change the plate width direction length of the spacer 3 or the position of the spacer 3 on the stacking surface of the electromagnetic steel sheet S. In addition, the plate width direction length of the spacer 3 is preferably equal to the plate width direction length of the electromagnetic steel sheet S. In other words, the spacer 3 preferably extends from one end of the electromagnetic steel sheet S in the plate width direction to the other end along the plate width direction.

[0031] In addition, the temperature rise of the wound core 1 can be suppressed as long as the gap portion 22A is provided in at least one side portion 22, but it is preferably provided in multiple sides 22. By providing the gap portion 22A in more sides 22, the contact area between the electromagnetic steel sheet S constituting the wound core 1 and the insulating oil is increased, and the heat of the electromagnetic steel sheet S can be dissipated more effectively. Furthermore, by providing the gap portion 22A in multiple sides 22, the temperature rise of the wound core 1 can be uniformly suppressed. Therefore, the gap portion 22A is more preferably provided in all four sides 22. In addition, in the case where there is a difference in length between the four sides 22 of the stack 2, the heat dissipation can be efficiently improved by providing a heat transfer path in the longer side. Specifically, if Figure 1 As shown, the laminated body 2 of the present embodiment has a pair of opposing long sides and a pair of opposing short sides, and a spacer is interposed at least in the long sides.

[0032] The filling factor of the electromagnetic steel sheet S in the side portion 22 having the gap portion 22A is preferably 86.0% or more and less than 91.0%. By setting the filling factor of the electromagnetic steel sheet S in the side portion 22 having the gap portion 22A to 86.0% or more, it is possible to maintain low iron loss. The filling factor of the electromagnetic steel sheet S in the side portion 22 having the gap portion 22A is more preferably 89.5% or more. In addition, by setting the filling factor of the electromagnetic steel sheet S in the side portion 22 having the gap portion 22A to less than 91.0%, the temperature rise of the wound core 1 can be further suppressed. In addition, the filling factor in the side portion 22 of the stack 2 can be calculated based on JIS C2550-5:2011. In addition, JIS C 2550-5:2011 corresponds to IEC 60404-13:1995, "Magnetic materials-Part 13:Methods of measurement of density, resistivity and stacking factor of electrical steel sheet and strip".

[0033] In addition, the gap portion 22A is preferably provided so that the distance between the inner peripheral surface of the side portion 22 and the gap portion 22A, the distance between the outer peripheral surface of the side portion 22 and the gap portion 22A, and the distance between adjacent gap portions 22A are equal in the stacking direction. Thus, the wound core 1 is uniformly cooled by the insulating oil, and the temperature rise of the wound core 1 is suppressed. In the case where the gap portion 22A is provided between the electromagnetic steel sheets S at one location in the side portion 22, the gap portion 22A is preferably provided at a position where the distance between the inner peripheral surface of the side portion 22 and the gap portion 22A and the distance between the outer peripheral surface of the side portion 22 and the gap portion 22A are substantially the same.

[0034] The spacer 3 is sandwiched between the electromagnetic steel sheets S in the side portion 22 to form a gap portion 22A. The raw material of the spacer 3 is preferably a non-magnetic body. If the spacer 3 is a non-magnetic body, it is possible to prevent eddy currents from being generated in the spacer 3, and as a result, it is possible to suppress the increase in iron loss. Specifically, the raw material of the spacer 3 is preferably resin, copper, or brass. Among these materials, the raw material of the spacer 3 is preferably copper. Copper is a material with high thermal conductivity, so by using copper for the spacer 3, the heat of the electromagnetic steel sheets S can be dissipated not only through the gap portion 22A but also through the spacer 3 itself.

[0035] In addition, the spacer 3 is preferably provided only at the side portion 22 of the stacked body 2. In other words, the gap portion 22A is preferably provided only at the side portion 22 of the stacked body 2. This is because, when the gap portion is provided at the curved portion 21, there is a greater concern about an increase in iron loss due to leakage of magnetic flux from the gap portion than an increase in the heat dissipation area. Therefore, it is preferable to provide the gap portion 22A at the side portion 22 which can ensure a larger heat dissipation area than the curved portion 21.

[0036] There is no particular limitation on the size of the spacer 3 as long as the gap portion 22A can be formed. However, as described above, in order to make the length of the gap portion 22A in the lamination direction 1 mm or more and 2 mm or less, the length of the spacer 3 in the lamination direction is preferably 1 mm or more and 2 mm or less. In addition, as long as the gap portion 22A that can suppress the temperature rise of the wound core 1 is formed, there is no particular limitation on the number of spacers 3 interposed between the electromagnetic steel sheets S at one location.

[0037] In addition, Figure 2 In one side portion 22, spacers 3 are sandwiched between three electromagnetic steel sheets S, but the number of electromagnetic steel sheets S sandwiched with spacers 3 is not limited to Figure 2 The manner shown can also be determined according to the size of the wound core 1. However, by placing the spacer 3 between the electromagnetic steel sheets S at one or more and three or less locations in at least one of the plurality of sides 22, the temperature rise of the wound core 1 can be suppressed, and the increase in iron loss can be further suppressed. Therefore, the spacer 3 is preferably placed between the electromagnetic steel sheets S at one or more and three or less locations in at least one of the plurality of sides 22.

[0038] <Second Embodiment>

[0039] Next, refer to Figure 1 as well as Figure 3 A wound core according to a second embodiment will be described. Figure 3 is a diagram showing an example of a wound core according to a second embodiment of the present invention, and is Figure 1 The X portion corresponds to an enlarged view of the portion.

[0040] like Figure 1 As shown, the wound core 1 of the present embodiment includes a laminate 2 formed by stacking a plurality of electromagnetic steel sheets S in a ring shape in a side view, and has a plurality of bent portions 21 and side portions 22 located between the adjacent bent portions 21. Figure 3As shown, the laminated body 2 includes a heat transfer body 4 at least in a portion between the stacked electromagnetic steel sheets S in at least one side 22 of the plurality of sides 22. The wound core 1 of the present embodiment is different from the wound core 1 of the first embodiment in that the heat transfer body 4 is included at least in a portion between the stacked electromagnetic steel sheets S in at least one side 22 of the plurality of sides 22. The basic structure of the laminated body 2 of the present embodiment is the same as that of the laminated body 2 of the first embodiment, and therefore, the description of the laminated body 2 is omitted here. The heat transfer body 4 will be described in detail below.

[0041] As described above, the heat transfer body 4 is provided in at least a portion between the stacked electromagnetic steel sheets S in at least one of the plurality of side portions 22. Figure 3 In the embodiment, the heat transfer body 4 is located between the electromagnetic steel sheets S at three locations in one side 22. Since the heat transfer body 4 is provided at least in a portion between the stacked electromagnetic steel sheets S in at least one side 22 among the plurality of sides 22, the heat generated in the electromagnetic steel sheets S flows through the heat transfer body 4 and is dissipated to the outside of the wound core 1. Therefore, the heat transfer body 4 is a heat transfer path for the heat generated in the electromagnetic steel sheets S.

[0042] The raw material of the heat transfer body 4 is preferably a material with high thermal conductivity. By making the raw material of the heat transfer body 4 a material with high thermal conductivity, the heat generated in the electromagnetic steel sheet S can be dissipated more efficiently. As a result, the temperature rise of the wound core 1 can be suppressed. In addition, the raw material of the heat transfer body 4 is preferably a non-magnetic and insulating material. If the raw material of the heat transfer body 4 is a non-magnetic and insulating material, it is possible to prevent eddy currents from being generated in the heat transfer body 4. As a result, the increase in iron loss can be suppressed. Specifically, the raw material of the heat transfer body 4 is more preferably phenolic resin (Bakelite). Phenolic resin has a high thermal conductivity and is a non-magnetic and insulating material, so it is possible to suppress the temperature rise of the wound core 1 by more efficiently dissipating the heat generated in the electromagnetic steel sheet S, and the increase in iron loss can be suppressed by preventing eddy currents from being generated in the heat transfer body 4. In more detail, the heat transfer body 4 is preferably a paper-based phenolic resin laminate, a cloth-based phenolic resin laminate, and a glass cloth-based phenolic resin laminate.

[0043] In addition, the shape of the heat transfer body 4 is not particularly limited, but it is preferably sandwiched widely between the electromagnetic steel sheets S at the side portion 22. If the heat transfer body 4 is sandwiched widely between the electromagnetic steel sheets S at the side portion 22, the contact area between the electromagnetic steel sheets S and the heat transfer body 4 increases, and the heat of the electromagnetic steel sheets S can be dissipated more effectively, and the temperature rise of the wound core 1 can be suppressed.

[0044] In addition, the temperature rise of the wound core 1 can be suppressed as long as the heat transfer body 4 is provided in at least one side portion 22, but it is preferably provided in multiple sides 22. By providing the heat transfer body 4 in more sides 22, the contact area between the electromagnetic steel sheet S and the insulating oil constituting the wound core 1 is increased, and the heat of the electromagnetic steel sheet S flows effectively to the insulating oil via the heat transfer body 4. In other words, the heat of the electromagnetic steel sheet S can be dissipated more effectively. Furthermore, by providing the heat transfer body 4 in multiple sides 22, the temperature rise of the wound core 1 can be uniformly suppressed. Therefore, it is more preferable that the heat transfer body 4 is provided in four sides 22.

[0045] The filling factor of the electromagnetic steel sheet S in the side portion 22 having the heat transfer body 4 is preferably 86.0% or more and less than 91.0%. By setting the filling factor of the electromagnetic steel sheet S in the side portion 22 having the heat transfer body 4 to 86.0% or more, low iron loss can be maintained. The filling factor of the electromagnetic steel sheet S in the side portion 22 having the heat transfer body 4 is more preferably 89.5% or more. In addition, by setting the filling factor of the electromagnetic steel sheet S in the side portion 22 having the heat transfer body 4 to less than 91.0%, the temperature rise of the wound core 1 can be further suppressed. In addition, the filling factor can be calculated based on JIS C 2550-5:2011, but in this embodiment, the mass of the heat transfer body 4 is not considered for calculation.

[0046] In addition, the heat transfer body 4 is preferably arranged so that the distance between the inner peripheral surface of the side 22 and the heat transfer body 4, the distance between the outer peripheral surface of the side 22 and the heat transfer body 4, and the distance between adjacent heat transfer bodies 4 are equal in the stacking direction. Thus, the wound core 1 can be more uniformly cooled by the insulating oil through the heat transfer body 4, and the temperature rise of the wound core 1 can be suppressed. In the case where the heat transfer body 4 is arranged between the electromagnetic steel sheets S at one location in the side 22, the heat transfer body 4 is preferably arranged at a position where the distance between the inner peripheral surface of the side 22 and the heat transfer body 4 and the distance between the outer peripheral surface of the side 22 and the heat transfer body 4 are approximately the same.

[0047] In addition, Figure 3 In one side portion 22, the heat transfer body 4 is sandwiched between three electromagnetic steel sheets S, but the number of the electromagnetic steel sheets S where the heat transfer body 4 is sandwiched is not limited to Figure 3 The method shown in the figure can also be determined according to the size of the wound core 1. However, by placing the heat transfer body 4 between the electromagnetic steel sheets S at one or more and three or less locations in at least one of the multiple sides 22, the temperature rise of the wound core 1 can be suppressed, and the increase in iron loss can be further suppressed. Therefore, the heat transfer body 4 is preferably placed between the electromagnetic steel sheets S at one or more and three or less locations in at least one of the multiple sides 22.

[0048] <Modification>

[0049] Several modified examples of the above-mentioned embodiment of the present invention are described below. In addition, each modified example described below can be applied to the above-mentioned embodiment of the present invention alone, or can be applied to the above-mentioned embodiment of the present invention in combination. In addition, each modified example can be applied instead of the structure described in the above-mentioned embodiment of the present invention, or can be applied in addition to the structure described in the above-mentioned embodiment of the present invention.

[0050] In addition, in each of the above-mentioned embodiments, the case where the outer periphery of the stack is an octagon is described, but the present invention is not limited to this. The outer periphery of the stack may be a polygon, a rounded square, an oblong or an elliptical shape, etc. For example, an oblong stack is manufactured by winding an electromagnetic steel sheet. On the other hand, an octagonal stack is manufactured by stacking a plurality of electromagnetic steel sheets bent into a ring shape in the plate thickness direction. Compared with a stack manufactured by winding an electromagnetic steel sheet, the filling factor of the bent portion of the stack manufactured by stacking a plurality of electromagnetic steel sheets bent into a ring shape in the plate thickness direction is easy to become smaller. Therefore, the filling factor of at least one of the multiple bent portions 21 of the stack 2 can also be increased. Specifically, by using a compression mechanism to compress the bent portion 21 from the inner circumference and the outer circumference, the gap between the electromagnetic steel sheets S in the bent portion 21 can be reduced. As a result, the filling factor of the bent portion 21 becomes higher, and the low noise of the stack 2 can be achieved.

[0051] In the above embodiment, the case where the inner periphery of the stack is a quadrilateral is described, but the present invention is not limited thereto, and the inner periphery of the stack can be a polygon, a rounded square, an oblong, or an ellipse. For example, when the inner periphery of the stack is an octagon, the portion connecting two adjacent vertices of the octagon becomes the corner, and when the inner periphery of the stack is an oblong, the arc-shaped portion becomes the corner. When the inner periphery of the stack is a polygon, a rounded square, an oblong, or an ellipse, the bent portion is a portion located between one side and another side adjacent to each other, and the electromagnetic steel sheets S are stacked in a bent manner relative to the extending direction of the electromagnetic steel sheets S in one side and the electromagnetic steel sheets S in the other side.

[0052] In addition, the inner periphery of the stack may be in a shape corresponding to the outer periphery. For example, when the outer periphery of the stack is an octagon, the inner periphery may be an octagon, and when the outer periphery of the stack is a rounded square, the inner periphery may be a rounded square.

[0053] Figure 2 as well as Figure 3The heat transfer path (gap portion 22A, heat transfer body 4) shown is only an example and is not limited to the above-mentioned form. For example, a concave portion may be formed by bending the edge portion 22 of one of the electromagnetic steel sheets S that overlap each other, and the inner side of the concave portion may be used as the gap portion.

[0054] The above describes a plurality of embodiments of the present invention. The wound core of these embodiments has a laminated body, which is formed by stacking a plurality of electromagnetic steel sheets in a ring shape in a side view, and has a plurality of curved portions and edges located between adjacent curved portions, and at least one of the plurality of edges has a heat transfer path facing the electromagnetic steel sheets in at least a portion between the stacked electromagnetic steel sheets. Through the heat transfer path, the heat generated in the electromagnetic steel sheets when an alternating current magnetic field is applied is efficiently dissipated, and the temperature rise of the wound core can be suppressed. In addition, the heat transfer path is provided in at least a portion between the stacked electromagnetic steel sheets in the edge, so that the leakage flux from the electromagnetic steel sheets to the heat transfer path is small, and a low iron loss can be maintained.

[0055] The wound core of the present embodiment can be applied to a transformer (not shown). The transformer of the present embodiment comprises the wound core of the present embodiment, a primary winding and a secondary winding. By applying an AC voltage to the primary winding, a magnetic flux is generated in the wound core, and a voltage is generated in the secondary winding by the change in the generated magnetic flux. The wound core is such that at least one of the multiple sides has a heat transfer path in at least a portion between the stacked electromagnetic steel sheets, so that the heat generated in the wound core is dissipated through the heat transfer path. As a result, it is possible to maintain a low iron loss and suppress temperature rise.

[0056] Next, the test example of the present invention is described. The conditions in this test example are a condition example adopted to confirm the feasibility and effect of the present invention, and the present invention is not limited to this condition example. The present invention can adopt various conditions as long as it does not deviate from the main purpose of the present invention and achieves the purpose of the present invention.

[0057] (Test Example 1)

[0058] Direct-oriented electromagnetic steel sheets with a thickness of 0.23 mm were stacked to produce a roughly octagonal stack with four bends and four sides. The following wound core was produced under the following conditions: the length of the stack in the stacking direction was 20 mm, and the four sides each had the number of gaps shown in Table 1. For each of the four sides of the stack, a spacer made of phenolic resin (Bakelite) was sandwiched between the electromagnetic steel sheets to provide a gap. The gap was set so that in the stacking direction, the distance between the inner circumference of the side and the gap, the distance between the outer circumference of the side and the gap, and the distance between adjacent gaps were equal. In transformer No. 2, the gap was set at a position where the distance between the inner circumference of the side and the gap was roughly equal to the distance between the outer circumference of the side and the gap. Regarding the gap, the length in the stacking direction was 1 mm, the length in the plate width direction was 300 mm, and the length in the winding direction was 100 mm. A winding is wound around the wound core, the wound core is placed in a box, and the box is filled with insulating oil to produce a transformer with a capacity of 20 kVA.

[0059] Regarding the wound core, the filling factor of the electromagnetic steel sheet in the edge was calculated based on JIS C 2550-5:2011. In addition, regarding the manufactured transformer, the iron loss (no-load loss) was measured based on JEC-2200. The temperature of the wound core was measured after the manufactured transformer was operated for 12 hours. Table 1 shows the number of gaps in each edge, the filling factor, the temperature, the iron loss, and the iron loss increase rate. In addition, Figure 4 The relationship between the filling factor of the electromagnetic steel sheets in the side portions and the winding core temperature is shown in Table 1. The filling factor in Table 1 is the average value of the filling factors of the electromagnetic steel sheets in the four side portions.

[0060] The manufactured transformers were evaluated according to the following criteria. When the transformer temperature is lowered based on the temperature of transformer No. 1 without a gap portion, and the iron loss increase rate based on the iron loss of transformer No. 1 is less than 10%, the evaluation result is set to "A (excellent)", and when the transformer temperature is not lowered based on the temperature of transformer No. 1 or the iron loss increase rate based on the iron loss of transformer No. 1 is more than 10%, the evaluation result is set to "B (good)". In addition, as an evaluation result, A is better than B. In addition, the invention examples in Table 1 refer to embodiments to which the present invention is applied, and the comparative examples refer to examples to which the present invention is not applied.

[0061] [Table 1]

[0062]

[0063] By increasing the number of gaps provided at the side, the contact area between the wound core and the insulating oil is increased, and the temperature of the wound core is reduced. Figure 4 As shown, as the filling factor decreases, the winding core temperature decreases. In transformer No. 4, the temperature rise is significantly suppressed. Although the temperature rise of transformer No. 5 is suppressed, the increase rate of iron loss exceeds 10%.

[0064] (Test Example 2)

[0065] Using a directional electromagnetic steel sheet with a thickness of 0.20 mm, a wound core was produced by the same method as in Test Example 1, and a transformer with a capacity of 1 kVA was manufactured using the produced wound core. The following wound core was manufactured under the following conditions: the length of the stack in the stacking direction is 20 mm, and the four sides each have a number of gap portions shown in Table 2. Regarding the gap portion, the length in the stacking direction is 1 mm, the length in the plate width direction is 200 mm, and the length in the winding direction is 70 mm. Regarding the manufactured transformer, the filling factor of the electromagnetic steel sheet in the edge, the temperature of the wound core, and the iron loss (no-load loss) were measured in the same manner as in Test Example 1. Table 2 shows the number of gap portions, the filling factor, the temperature, the iron loss, and the iron loss increase rate for each edge. In addition, Figure 5 The relationship between the filling factor of the electromagnetic steel sheet in the side and the winding core temperature is shown in Table 2. In addition, the filling factor in Table 2 is the average value of the filling factor of the electromagnetic steel sheet in the four sides. The transformer was evaluated based on the same criteria as in Test Example 1. In addition, the invention example in Table 2 refers to an embodiment to which the present invention is applied, and the comparative example refers to an example to which the present invention is not applied.

[0066]

Table 2

[0067]

[0068] By increasing the number of gaps provided at the side, the contact area between the wound core and the insulating oil is increased, and the temperature of the wound core is reduced. Figure 4 As shown, as the filling factor decreases, the winding core temperature decreases. In transformer No. 4, the temperature rise is significantly suppressed. Although the temperature rise of transformer No. 5 is suppressed, the increase rate of iron loss exceeds 10%.

[0069] (Test Example 3)

[0070] Directional electromagnetic steel sheets with a thickness of 0.23 mm were stacked to produce a roughly octagonal stack with four bends and four sides. The following wound core was produced under the following conditions: the length of the stack in the stacking direction was 20 mm, and one of the four sides had a number of heat transfer bodies shown in Table 3. With respect to one side of the stack, a gap portion was provided by sandwiching a phenolic resin spacer between the electromagnetic steel sheets. The gap portion was provided so that, in the stacking direction, the distance between the inner circumference of the side and the gap portion, the distance between the outer circumference of the side and the gap portion, and the distance between adjacent gap portions were equal. In transformer No. 2, the gap portion was provided at a position where the distance between the inner circumference of the side and the gap portion and the distance between the outer circumference of the side and the gap portion were roughly equal. With respect to the gap portion, the length in the stacking direction was 1 mm, the length in the plate width direction was 150 mm, and the length in the winding direction was 100 mm. A winding is wound on the winding core, and the winding core is placed in a box and the box is filled with insulating oil to manufacture a transformer with a capacity of 10kVA. Regarding the manufactured transformer, the filling factor of the electromagnetic steel sheet in the edge with the gap portion, the temperature of the winding core, and the iron loss (no-load loss) were measured by the same method as in Test Example 1. Table 3 shows the number of gap portions in the edge with the gap portion, the filling factor, the temperature, the iron loss, and the iron loss increase rate. In addition, the filling factor in Table 3 is the filling factor of the electromagnetic steel sheet in the edge with the gap portion. The transformer was evaluated based on the same criteria as Test Example 1. In addition, the invention example in Table 3 refers to an embodiment to which the present invention is applied, and the comparative example refers to an example to which the present invention is not applied.

[0071]

Table 3

[0072]

[0073] As described above, according to the present invention, it is possible to suppress a temperature increase while maintaining low iron loss.

[0074] The preferred embodiments and examples of the present invention are described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. Anyone with common knowledge in the technical field of the present invention can think of various changes or modifications within the scope of the technical ideas recorded in the scope of the claims, and it should be understood that these also belong to the technical scope of the present invention.

[0075] The following supplementary notes are further disclosed with respect to the above-mentioned embodiment.

[0076] (Note 1)

[0077] A wound iron core includes a stacked body in which a plurality of electromagnetic steel sheets are stacked in a ring shape in side view.

[0078] The stacked body has a plurality of curved portions and a plurality of side portions located between adjacent curved portions.

[0079] At least one of the plurality of side portions has a heat transfer path facing the electromagnetic steel sheets in at least a portion between the stacked electromagnetic steel sheets.

[0080] The heat transfer path is only located at the edge.

[0081] (Note 2)

[0082] In the wound core according to Supplementary Note 1, a filling factor of the electromagnetic steel sheet in the side portion having the heat transfer path is 86.0% or more and less than 91.0%.

[0083] (Note 3)

[0084] In the wound core according to Supplementary Note 1 or Supplementary Note 2, a length of the heat transfer path in a lamination direction of the electromagnetic steel sheets is 1 mm or more and 2 mm or less.

[0085] (Note 4)

[0086] In the wound core according to any one of Supplementary Notes 1 to 3, the heat transfer path is between the electromagnetic steel sheets at one or more and three or less locations in at least one of the plurality of side portions.

[0087] (Note 5)

[0088] In the wound core according to any one of Supplementary Notes 1 to 4, a spacer is provided in at least a portion between the stacked electromagnetic steel sheets in at least one of the plurality of side portions.

[0089] A gap portion generated between the electromagnetic steel sheets by the spacer serves as the heat transfer path.

[0090] (Note 6)

[0091] In the wound core described in Supplementary Note 5, the spacer is a non-magnetic body.

[0092] (Note 7)

[0093] In the wound core according to any one of Supplementary Notes 1 to 4, the heat transfer path is formed of a non-magnetic and insulating heat transfer body.

[0094] (Note 8)

[0095] In the wound core described in Supplementary Note 7, the heat transfer path is formed of a phenolic resin.

[0096] (Note 9)

[0097] In the wound core described in any one of Supplementary Notes 1 to 8, the heat transfer path exists in all the side portions.

[0098] (Note 10)

[0099] In the wound core described in any one of Supplementary Notes 1 to 8, the side portions include a first side portion and a second side portion longer than the first side portion,

[0100] The heat transfer path is located only at the second side.

[0101] (Note 11)

[0102] In the wound core according to any one of Supplementary Notes 1 to 10, the shape of the stacked body when viewed from the side is an octagon having the four side portions and the four bent portions.

[0103] (Note 12)

[0104] A wound iron core includes a laminated body, wherein the laminated body is formed by laminating a plurality of electromagnetic steel sheets in a ring shape in a side view, and has a plurality of bent portions and side portions located between adjacent bent portions.

[0105] At least one of the plurality of side portions has a heat transfer flow path facing the electromagnetic steel sheets in at least a portion between the stacked electromagnetic steel sheets.

[0106] (Note 13)

[0107] In the wound core according to Supplementary Note 12, a filling factor of the electromagnetic steel sheet in the side portion having the heat transfer flow path is 86.0% or more and less than 91.0%.

[0108] (Note 14)

[0109] In the wound core according to Supplementary Note 12 or Supplementary Note 13, a length of the heat transfer path in a lamination direction of the electromagnetic steel sheets is 1 mm or more and 2 mm or less.

[0110] (Note 15)

[0111] In the wound core according to any one of Supplementary Notes 12 to 14, the heat transfer path is provided between the electromagnetic steel sheets at not less than one and not more than three locations in at least one of the plurality of side portions.

[0112] (Note 16)

[0113] In the wound core according to any one of Supplementary Notes 12 to 15, a spacer is provided in at least a portion between the stacked electromagnetic steel sheets in at least one of the plurality of side portions.

[0114] A gap portion generated between the electromagnetic steel sheets by the spacer serves as the heat transfer path.

[0115] (Note 17)

[0116] In the wound core according to Supplementary Note 16, the spacer is a non-magnetic body.

[0117] (Note 18)

[0118] In the wound core according to any one of Supplementary Notes 12 to 15, the heat transfer path is formed of a non-magnetic and insulating heat transfer body.

[0119] (Note 19)

[0120] In the wound core described in Supplementary Note 18, the heat transfer path is formed of a phenolic resin.

[0121] (Note 20)

[0122] In the wound core according to any one of Supplementary Notes 12 to 19, the shape of the stacked body when viewed from the side is an octagon.

[0123] In addition, the entirety of the invention of Japanese Patent Application No. 2019-160544 filed on September 3, 2019 is incorporated into this specification by reference.

[0124] All documents, patent applications, and technical specifications described in this specification are incorporated herein by reference to the same extent as if each document, patent application, and technical specification were specifically and individually described.

Claims

1. A wound core, wherein: A laminated body is provided in which a plurality of electromagnetic steel sheets are stacked in a ring shape in a side view so as to overlap each other. The laminate has four curved portions and four side portions located between the adjacent curved portions, and has an octagonal shape when viewed from the side. At least one of the four sides of the stacked body has a heat transfer path facing the electromagnetic steel sheets in at least a portion between the stacked electromagnetic steel sheets. The heat transfer path is only located at the edge.

2. The wound core according to claim 1, wherein: The filling factor of the electromagnetic steel sheet in the side portion having the heat transfer path is 86.0% or more and less than 91.0%.

3. The wound core according to claim 1 or 2, wherein: The length of the heat transfer path in the stacking direction of the electromagnetic steel sheets is 1 mm or more and 2 mm or less.

4. The wound core according to claim 1 or 2, wherein: The heat transfer path is located between the electromagnetic steel sheets at one or more and three or less locations in at least one of the four sides.

5. The wound core according to claim 1 or 2, wherein: A spacer is provided at least partially between the stacked electromagnetic steel sheets in at least one of the four sides. A gap portion generated between the electromagnetic steel sheets by the spacer serves as the heat transfer path.

6. The wound core according to claim 5, wherein: The spacer is a non-magnetic body.

7. The wound core according to claim 1 or 2, wherein: The heat transfer path is formed by a non-magnetic and insulating heat transfer body.

8. The wound core according to claim 7, wherein: The heat transfer path is formed of phenolic resin.

9. The wound core according to claim 1 or 2, wherein: The above-mentioned heat transfer paths exist in all the above-mentioned edges.

10. The wound core according to claim 1 or 2, wherein: The side portions include a first side portion and a second side portion that is longer than the first side portion. The heat transfer path is located only at the second side.

11. The wound core according to claim 5, wherein: A plurality of the spacers are present between the electromagnetic steel sheets, and the gap portion is formed between the spacers adjacent to each other.

12. The wound core according to claim 5, wherein: The spacer extends from one end to the other end in the sheet width direction of the electromagnetic steel sheet.

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