JP2013153113A - Rectangular wire and coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectangular wire which is improved to solve such a problem that insulation deteriorates starting from a portion becoming the outside when being bent, and such a problem that the heat dissipation efficiency is low because the heat dissipation area on the outside is small, and to provide a coil formed by winding this rectangular wire.SOLUTION: A rectangular wire 10 consists of a rectangular conductor 1 having a cross-sectional shape formed by connecting two ends of an end side 1a, which is located on the outside when being bent and is a convex curve outwardly, with two other sides 1c, 1c, respectively, and an insulation coating 2 formed around the rectangular conductor 1. A coil 100 is formed by winding this rectangular wire 10 edgewise around the teeth of a reactor core or the stator core of a motor.

Description

  The present invention relates to an improved rectangular wire and a coil formed by winding the rectangular wire.

  The coil formed around the teeth of the stator that makes up the motor and the windings that make up the coil formed around the core of the reactor have been improved in place of the conventional round circular wire. From the point of view, a rectangular wire is applied.

  A flat wire is made up of a copper rectangular conductor having a substantially rectangular cross section, that is, a corner with a rounded corner, and a dielectric coating formed around the rectangular conductor. It is common to be done. This insulating film is prepared by dissolving a thermosetting enamel resin around a flat wire in a solvent and applying it to a thickness of several μm, heat-treating it to harden the coating layer, and repeating this process several times to obtain an enamel film with a desired thickness. Is formed.

  When this rectangular wire is wound to form a coil, the end of the rectangular cross section is placed on the core side such as a tooth or a reactor, and the long side is wound in a posture raised from the core, so-called edgewise A coil is formed by winding.

  Here, with reference to FIGS. 4 and 5, a problem of a conventional flat wire and a coil formed by winding the flat wire around the core will be described.

  As shown in FIG. 4a, the conventional rectangular wire is substantially rectangular in cross-sectional view as shown in FIG. 4a (the corner portion has a small diameter curvature) and is formed on the surface of the rectangular conductive wire D made of copper. To form a rectangular wire W. Here, as described above, in the process in which enamel coating Z having a desired thickness is formed by repeating enamel resin application and heat treatment a predetermined number of times, the surface tension from the flat wire D until the liquid enamel is reactively cured. In response to Q, the thickness of the corner portion is relatively thinner than the thickness t1 of the general part (thickness t2 is t2 <t1), and the film thickness is already non-uniform during enamel coating. It has become. When edgewise winding is performed, winding is performed such that one of two short sides of a substantially rectangular cross section is on the inner side of bending and the other is on the outer side of bending.

  Then, the rectangular wire W having the cross section shown in FIG. 4B is edgewise wound around the core CO with a predetermined number of turns, thereby forming a coil C composed of the rectangular wire W as shown in FIG.

  Thus, when the coil C is formed by edgewise winding the flat wire W, the enamel coating Z on the outer side of the bend is stretched to a thickness t3 (<t1), which is already relatively thin before the bending process. The thickness of the corner portion is reduced from the initial t2 to a thinner thickness t4.

  This bending process causes a decrease in insulation depending on the corner thickness t4 of the outer region (bending outer region), so there is a great restriction on the bending radius during engine-wise winding at the design stage. Will occur.

  In the case where a coil is formed by winding a rectangular wire around the reactor core in the core, the above problem becomes more remarkable because the flat wire has a high flatness.

  Further, from the viewpoint of heat dissipation, when the coil is radiated to cool the coil by radiating the heat generated by energizing the coil, the heat is radiated mainly from the outside of the coil (heat radiation is in the X direction). As apparent from the comparison with the round wire, the end of the flat wire W on the outer side of the bend is a straight short side, so that the heat radiation area outside the flat wire W is reduced and the heat radiation efficiency is low. ing.

  Thus, while the conventional rectangular wire can improve the space factor, the problem of insulation deterioration starting from an extremely thin insulating film at the corner outside the bend, and the heat dissipation area of the insulating film outside the bend There is a problem such as low heat dissipation efficiency due to the small size, and solving these problems is one of the urgent solutions in the technical field.

  Here, in Patent Document 1, a coil having a plurality of turns formed by winding a winding spirally, an annular magnetic core in which the coil is disposed, and a combination of the coil and the magnetic core A reactor including an outer resin portion that covers the outer periphery of the coil is disclosed. Here, the winding is made of a rectangular wire that does not have an insulating layer such as enamel coating, and the winding that constitutes each turn of the coil. A reactor is disclosed in which a constituent resin of an outer resin portion is interposed between wires to insulate adjacent turns. The use of bare wire for the winding makes it possible to easily form a coil and to form an insulating structure between adjacent turns at the same time as the formation of the outer resin part, so the productivity of the reactor It is excellent in.

  However, since the bare wire is used, if the resin is not sufficiently impregnated around the entire circumference of the bare wire, there is a big problem that the insulating property is remarkably lowered, which is not practical. In addition, when the bare wire is a flat wire, the insulation film formed at the corners due to surface tension during the resin curing process becomes thin. It is the same as above, and there is still a problem of insulation reliability at the corner, and low heat dissipation due to the problem of insulation deterioration starting from the insulating coating at the corner and the outside heat dissipation area is small It will not solve the efficiency problem.

JP 2010-267932 A

  The present invention has been made in view of the above-mentioned problems, and by improving the flat wire, there is a problem in that a part of the outer portion becomes the starting point when the bending is performed and the insulation is likely to be lowered. An object of the present invention is to provide a flat wire that can solve both of the problems of low heat dissipation efficiency due to the small heat dissipation area on the outside and a coil formed by winding the flat wire.

  In order to achieve the above-mentioned object, the rectangular wire according to the present invention is a curved line in which an end located outside the bend is bent outward when bent, and the two ends of the end are the other two. A flat conducting wire having a cross-sectional shape connecting the sides and an insulating film formed around the flat conducting wire.

  The flat wire of the present invention has a cross-sectional shape that improves the cross-sectional shape of the conventional flat wire, and has an end that becomes the outer side when the flat wire is bent, such as edgewise winding, with a convex curve outward. It is comprised from the flat conducting wire and the insulating film formed in the circumference | surroundings of this flat conducting wire.

  Therefore, the cross-sectional shape of the rectangular conducting wire is a cross-sectional shape in which a cross-section defined by a convex curved region is added to the outer side of one short side of a conventional substantially rectangular cross-section.

  Here, the “outwardly convex curve” includes a semicircular shape, an arc shape, a semielliptical shape, and the like, and among them, a semicircular shape in which a corner portion is completely eliminated is preferable.

  The end side that becomes the outer side when bent is a curve that is convex outward, and the two end portions of the end side have a cross-sectional shape that connects the other two sides, respectively. The corners in the outer region of the bend can be eliminated, and no portion where the insulating coating becomes extremely thin in the process of forming the insulating coating in the outer region of the bending is generated. For this reason, even if the region outside the bend is pulled by bending and the insulating coating becomes somewhat thin, an extremely thin insulating coating that reduces the insulating property as in the case of a rectangular conductor with a substantially rectangular cross section, Therefore, the problem of deterioration of insulation in the region that is outside by bending is effectively solved.

  Furthermore, it is a curve that is convex outward on the outer edge when bent and has a cross-sectional shape in which the two ends of the edge are connected to the other two edges, respectively. As compared with the conventional rectangular conductor having a substantially rectangular cross section, the heat radiation area on the outside is significantly increased, and the heat radiation efficiency can be improved.

Thus, the rectangular wire according to the present invention is only improved in cross-sectional shape so that the edge located on the outer side of the bending becomes a curved curve outward when bent, and the manufacturing cost of the rectangular wire is reduced. It is not something that will soar.
The present invention also extends to a coil formed by winding the above-described rectangular wire of the present invention.

  The coil of this invention can be formed with respect to the teeth and the reactor core which comprise the stator core of a motor. In particular, when the coil of the present invention is applied to a reactor core having a cross-sectional shape with a high flatness of a flat wire, the improvement effect is tremendous with respect to a conventional reactor in which insulation deterioration is remarkable.

  As can be understood from the above description, according to the rectangular wire of the present invention and the coil formed by winding the same, the cross section of the rectangular wire is improved and positioned on the outer side of the bend when it is bent. Since the end side is a curved line that protrudes outward, and the two end portions of the end side are connected to each other two sides, the rectangular wire is positioned outside the bend when bent. The corner portion in the region is eliminated, which can eliminate the occurrence of a region in which the thickness of the insulating coating formed around the flat conducting wire is extremely thin, and the problem of reduced insulation is solved. Furthermore, since it has a cross-sectional shape in which the end side that is the outside of the bend when bent is curved outwardly, the heat dissipation area on the outside of the bend increases, and the heat dissipation efficiency can be improved.

It is the perspective view explaining embodiment of the flat wire of this invention. FIG. 2 is a cross-sectional view illustrating a part of a coil formed by edgewise winding a rectangular wire in FIG. 1 around a reactor core. In verification of insulation of a rectangular wire after bending, it is a sectional view showing a rectangular wire model before bending, wherein (a) is a diagram showing a comparative example model, and (b) is an example model. FIG. (C) is the schematic diagram which imaged edgewise bending. (A) is a figure explaining the conventional rectangular conducting wire of the cross-section view, (b) explains the conventional rectangular conducting wire formed by forming an insulating film around the rectangular conducting wire of (a). FIG. It is the figure explaining the conventional coil formed by winding the rectangular wire shown in FIG. 4 around the core.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a rectangular wire of the present invention and a coil formed by winding the rectangular wire will be described with reference to the drawings.

(Embodiment of flat wire)
FIG. 1 is a perspective view illustrating an embodiment of a flat wire according to the present invention. The illustrated flat wire 10 is formed as a whole by forming an insulating coating 2 such as an enamel coating around a rectangular conductive wire 1 made of copper.

  The flat conducting wire 1 constituting the flat wire 10 has a cross-sectional shape in which the short side 1b located inside when the wire is bent has a straight line shape, and the opposite end side, that is, the bent outside when bent. The short side 1a located in the shape of a semicircle is formed by connecting these two short sides 1a and 1b to the two long sides 1c to form an outline line of the cross section.

  An insulating coating made of an enamel coating having a desired thickness is obtained by applying a thermosetting enamel resin dissolved in a solvent to the surface of the flat conductor wire 1 having such a cross-sectional shape, heat-treating the coating layer, and repeating this treatment a plurality of times. 2 is formed. At this time, there is no corner portion extending from the straight long side 1c to the semicircular short side 1a. For this reason, surface tension is applied from the flat conductor 1 until the enamel resin is reactively cured. Even so, there is no region where the film thickness becomes thin (thickness s1 from the long side 1c to the short side 1a).

  On the other hand, a corner portion exists between the short side 1b and the long side 1c, and the film thickness of the corner portion is received by receiving the surface tension Q from the flat wire 1 until the enamel resin is reactively cured. Is relatively thin (thickness s2 and s2 <s1).

  However, since the flat wire 10 shown in the figure has a relatively thin insulating coating 2 in the inner region when it is bent, the thickness of the insulating coating 2 at the corners inside the bending is increased by bending. It will never be thinner than s2.

  In the illustrated rectangular wire 10, the relatively thin insulating coating 2 does not exist in the outer region when bent (the thickness is s 1 from the long side 1 c to the short side 1 a). Even if the insulating coating 2 in the outer region is pulled and becomes somewhat thin, the thickness is not extremely reduced to such an extent that the insulating property is lowered.

(Coil embodiment)
FIG. 2 is a cross-sectional view of a part of a coil formed by edgewise winding the flat wire of FIG. 1 around the reactor core.

  The thickness s1 ′ of the insulating coating 2 corresponding to the short side 1a located outside each rectangular wire 10 constituting the coil 100 is slightly larger than the thickness s1 of the insulating coating 2 corresponding to the long side 1c by bending. Although it is thin, since there is no corner portion in the outer region of the bend, there is no portion where the thickness of the insulating coating is extremely thin to the extent that the insulation is lowered.

  And when FIG. 2 and FIG. 5 are compared, the area of the insulating coating in the region outside the bend is compared to the insulating coating Z corresponding to the straight short side constituting the conventional rectangular wire W of FIG. The area of the insulating coating 2 corresponding to the semicircular short side 1a shown in FIG. 2 is remarkably large, and this greatly improves the heat dissipation performance from the insulating coating 2 outside the bend (heat dissipation is in the X direction). ), A coil with high heat dissipation efficiency.

[Calculation results verifying insulation of rectangular wire after bending]
The inventors set a rectangular wire model of the cross section shown in FIGS. 3a and 3b (FIG. 3a is a comparative example model and FIG. 3b is an example model), and a rectangular wire model having the dimensions shown in Table 1 below. The 1/4 circumference and the elongation of the insulation coating when each rectangular wire was edgewise bent with a radius of 6 mm were calculated. The calculation results are shown in Table 2 below. FIG. 3c is a schematic diagram in which the edgewise bending related to the embodiment is imagined, but the image of the embodiment can be applied to the comparative example except that there is no shoulder bending.

  As a precondition for this calculation, when a wide flat wire is edgewise bent, the basic wire is constrained bending to prevent the flat wire from wavy, and this prevents the thickness of the flat wire from becoming thicker than 1.0 mm. And Also, the bending center of the edgewise bending process is the width center of the flat wire.

  From Table 2 showing the calculation results, the thinnest part of the insulating coating of the comparative example is a corner, but this is the part where the distance from the bending center (bending radius) is the same as the outside of the bend and the elongation is highest. For this reason, the insulation film thickness after bending becomes too thin, and there is a risk of insulation deterioration.

  Bending with a larger bending radius than the edgewise bending process with a radius of 6 mm, which is the condition for this verification, is safer from the viewpoint of insulation, but because the bending radius is restricted in this way, the design flexibility is increased. Will be reduced.

  On the other hand, in the rectangular wire of the example, the elongation percentage of the shoulder portion is small, and since the insulating film thickness before bending is not a particularly thin part, a sufficient thickness is ensured in the insulating coating even after bending, There is no risk of insulation loss.

  In addition, for the outer side of the bend with the highest elongation rate in both the comparative example and the example, the insulating film thickness before the bending process is thicker than the corner portion of the comparative example, so a sufficient thickness is ensured in the insulating film even after the elongation. In both cases, there is no risk of lowering insulation at this site.

[Calculation results verifying cooling performance of rectangular wire after bending]
Under the conditions used in the above calculation, the area outside the coil (heat dissipating area) obtained by stacking the flat wire with edge radius bending with a radius of 6mm is calculated.

  Here, as a precondition for this calculation, an actual reactor coil is stacked for about 20 turns, but this is simplified and compared with one copper wire (flat conductor). Also, since the insulation film thickness varies depending on the part, this is simplified and compared with the area outside the bending of the copper wire.

Regarding the comparative model, since the corner portion has a small diameter R = 0.1 and the length of the straight portion of the short side of the copper wire is 0.8 mm, the area outside the bending of the copper wire of the comparative model is ( 2π × 0.1) / 4) × 2 + (1.0−2 × 0.1) = 1.11 mm ²

On the other hand, in the case of the example model, since the semicircular radius R = 0.5, the area outside the bending of the copper wire is (2π × 0.5) /2=1.57 mm ² .

  From this calculation result, it has been estimated that the heat radiation area of the rectangular wire outside the bend of the example model will be 40% more than that of the flat wire model, and it is confirmed by this calculation result that the cooling performance is remarkably improved. It has been.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Flat conducting wire, 1a ... Short side (short side located outside when bent), 1b ... Short side (short side located inside when bent), 1c ... Long side, 2 ... Insulating coating, 10 ... flat wire, 20 ... reactor wire, 100 ... coil

Claims (3)

A rectangular conductor having a cross-sectional shape in which the end side located outside the bend when bent is a convex curve outward, and the two end portions of the end side connect each other two sides;
A flat wire comprising an insulating film formed around a flat conductive wire.   The rectangular wire according to claim 1, wherein the end side is semicircular.   A coil formed by winding the flat wire according to claim 1.

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