Insulated Wire and Wire Harnesses

Abstract

To provide an insulation wire which can be flexibly bent into a complicated shape while having a flat part where the cross section of an electric conductor is flat-shaped; and to provide a wire harness with such an insulation wire.SOLUTION: An insulation wire 1 has a flat part 20 and a low flat part 30 along an axial direction x with each of single wires constituting a conductor 11 and insulation coating 13 continuing mutually. The outer shape of the conductor 11 on a cross section orthogonal to the axial direction x, on the flat part 20, has a flat shape, and on the low flat part 30, has a shape with a flatness degree smaller than that of the flat part 20. In the cross sections of the conductors 11 of both the flat part 20 and the low flat part 30, of outer peripheral parts facing the outer peripheries of the conductors 11, a deformation rate from the circular shape of the single wire is smaller than that of the central part of the conductor 11 on a width direction end part corresponding to the width direction outer side of the flat shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an insulated wire and a wiring harness. [Background technology]

[0002] A flat cable made of a flat conductor is known. The flat cable can occupy less space when installed compared to a general electric wire having a conductor with a substantially circular cross section.

[0003] In conventional flat cables, rectangular conductors are often used as the conductor, as disclosed in Patent Documents 1 and 2. A rectangular conductor is a metal wire formed into a rectangular cross section. In addition, Patent Documents 3 to 5, filed by the applicants, disclose electric wire conductors in which a stranded wire made by twisting together multiple strands is formed into a flat shape from the viewpoint of achieving both flexibility and space saving. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-130739 A [Patent Document 2] JP 2019-149242 A [Patent Document 3] International Publication No. 2019 / 093309 [Patent Document 4] International Publication No. 2019 / 093310 [Patent Document 5] International Publication No. 2019 / 177016 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Documents 3 to 5, an insulated electric wire having a flat stranded wire as a conductor, which is a stranded wire in a flat shape, is excellent in both space-saving and flexibility. However, although the flat stranded wire exhibits very high flexibility when bent in the height direction (flat direction) of the flat shape, the flexibility when bent in the width direction (edgewise direction) of the flat shape tends to be lower than when bent in the height direction. By utilizing the space-saving property of the flat stranded wire and its flexibility in the height direction, the insulated electric wire having the flat stranded wire can be suitably used for wiring in various spaces such as narrow spaces. However, when an insulated electric wire having the flat stranded wire is used for an application involving complex bending such as three-dimensional wiring, bending in the height direction alone may not be enough to accommodate the complex bending required for the wiring route.

[0006] In order to fully accommodate complex bending, it is necessary to bend the flat stranded wire in the width direction as well, but as described above, bending the flat stranded wire in the width direction is more difficult to flexibly than bending it in the height direction. Therefore, in the field of automotive electric wires, etc., it is desired to develop an insulated electric wire that can easily accommodate complex bending such as three-dimensional wiring while utilizing the space-saving properties of the flat stranded wire. In particular, when the conductor cross-sectional area is increased in order to accommodate a large current, the flexibility of the conductor tends to decrease, but it is desirable that even an insulated electric wire with a large conductor cross-sectional area can accommodate complex bending while also achieving space-saving properties.

[0007] In view of the above, an object of the present invention is to provide an insulated wire that can be flexibly bent into a complex shape while having a flat portion in which the cross section of the conductor is flattened, and a wire harness including such an insulated wire. [Means for solving the problem]

[0008] An insulated electric wire according to a first embodiment of the present disclosure is an insulated electric wire having a conductor formed by twisting together a number of strands and an insulating coating that covers the outer periphery of the conductor, wherein each of the strands that constitute the conductor and the insulating coating are continuous with each other, and has a flat portion and a low flat portion along the axial direction, and the outer shape of the conductor in a cross section perpendicular to the axial direction of the insulated electric wire has a flat shape in the flat portion and a shape with a smaller flatness than the flat portion in the low flat portion, and in the cross section of the conductor in both the flat portion and the low flat portion, the deformation rate of the strands from a circular shape is smaller at the widthwise end portion corresponding to the widthwise outer side of the flat shape, among the outer periphery facing the outer periphery of the conductor, than at the central portion of the conductor.

[0009] The insulated wire according to the second embodiment of the present disclosure is manufactured by compressing a conductor formed by twisting together a number of strands into a flat shape, coating the outer periphery with an insulating coating to form an insulated wire, and then applying force from the outside to the inside in the width direction of the flat shape in a certain region along the axial direction of the insulated wire to reduce the flatness of the conductor, thereby forming a low-flatness portion, and leaving the area other than the low-flatness portion as a flat portion.

[0010] The wire harness of the present disclosure includes the insulated wire. Effect of the Invention

[0011] The insulated electric wire and wire harness according to the present disclosure are an insulated electric wire that has a flat portion in which the cross section of the conductor has a flat shape, yet can be flexibly bent into a complex shape, and a wire harness that includes such an insulated electric wire. [Brief description of the drawings]

[0012] [Figure 1] 1A to 1C are schematic diagrams showing an insulated electric wire according to an embodiment of the present disclosure. Fig. 1A is a perspective view. Fig. 1B is a cross-sectional view showing a flat portion corresponding to cross section AA in Fig. 1A, and Fig. 1C is a cross-sectional view showing a low flat portion corresponding to cross section BB in Fig. 1A. In each drawing, the wires constituting the conductor are omitted. [Diagram 2] 2 is a cross-sectional view showing the flat portion of the insulated wire, with regions R1 to R3 encircled and shown in an enlarged manner. [Diagram 3] 3 is a cross-sectional view showing the low flat portion of the insulated wire, with regions R1 to R3 encircled and shown in an enlarged scale. [Figure 4] FIG. 4 is a cross-sectional view showing a low flat portion of an insulated electric wire according to a modified embodiment. [Diagram 5] FIG. 5 is a diagram illustrating the method for evaluating the flexibility of the insulated wire in test [1]. [Figure 6] Figures 6A and 6B are detailed images of the cross sections of the flat and low flat parts, respectively, of the insulated wire in test [2]. [Figure 7] 7A to 7C are images of the cross sections of the flat part (left) and the low flat part (right) of the insulated wire for conductor cross-sectional areas of 15 mm2, 60 mm2, and 130 mm2, respectively, in test [3]. [Figure 8] Fig. 8A is a photograph showing the appearance of the insulated electric wire used as a sample in the test [4], and Fig. 8B is an image showing the cross section taken at positions P1 to P5 in Fig. 8A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. An insulated electric wire according to a first embodiment of the present disclosure is an insulated electric wire having a conductor formed by twisting together a number of strands and an insulating coating that covers the outer periphery of the conductor, wherein each of the strands that constitute the conductor and the insulating coating are continuous with each other, and has a flat portion and a low flat portion along the axial direction, and the outer shape of the conductor in a cross section perpendicular to the axial direction of the insulated electric wire has a flat shape in the flat portion and a shape with a smaller flatness than the flat portion in the low flat portion, and in the cross section of the conductor in both the flat portion and the low flat portion, the deformation rate of the strands from a circular shape is smaller at the widthwise end portion corresponding to the widthwise outer side of the flat shape, among the outer periphery facing the outer periphery of the conductor, than at the central portion of the conductor.

[0014] The insulated wire has a flat portion in which the conductor has a flat shape and a low flat portion in which the conductor has a small flatness, which are continuous. In the low flat portion, the flatness of the conductor is low, so that the difference in flexibility depending on the bending direction is small compared to the flat portion, and the wire can be flexibly bent in all directions, including the width direction of the flat shape. Therefore, in the insulated wire, the low flat portion can be used to flexibly bend the wire into a complex shape, such as a three-dimensional wiring arrangement. By utilizing the bending flexibility in all directions of the low flat portion and the bending flexibility and space saving in the height direction of the flat portion, an insulated wire excellent in both bending freedom and space saving can be obtained. Such an insulated wire can be suitably used in places where space is limited and wiring in a complex path is required, such as inside an automobile.

[0015] Furthermore, in the above-mentioned insulated electric wire, the deformation rate of the wire from the circular shape is smaller at the width direction end of the conductor in the flat portion and the low flat portion than at the central portion. In this way, an insulated electric wire in which the deformation rate of the wire is smaller at the width direction end of the conductor in both the flat portion and the low flat portion than at the central portion can be easily formed by compressing the conductor into a flat shape, forming an insulating coating, and then applying a force to compress the flat conductor from the outside in the width direction to deform the conductor, thereby reducing the flatness of the conductor and forming the low flat portion. If the low flat portion is formed by this method in a portion of a flat electric wire that needs to be bent into a complex shape, such as a three-dimensional arrangement, it becomes possible to arrange the insulated electric wire in various spaces and in various shapes while achieving both space saving and bending flexibility.

[0016] Here, in the cross section of the conductor in both the flat portion and the low flat portion, among the outer peripheral portion facing the outer periphery of the conductor, the deformation rate of the wire from the circular shape at the widthwise end portion may be smaller than that at the heightwise end portion corresponding to the outer side in the height direction of the flat shape. Also, in the low flat portion, the deformation rate of the wire from the circular shape at the widthwise end portion may be 70% or less than that at the central portion. As described above, an insulated electric wire having a low flat portion in which the deformation rate of the wire at the widthwise end portion of the conductor is smaller than that at not only the central portion but also the heightwise end portion, and a low flat portion in which the deformation rate of the wire at the widthwise end portion is significantly smaller than that at the central portion, can be easily obtained by using an insulated electric wire in which a conductor is compressed into a flat shape as a raw material and forming a low flat portion in a partial region of the insulated electric wire.

[0017] In the low flatness portion, the deformation rate of the wire from a circular shape may be 5% or more in the central portion. By increasing the deformation rate of the wire in the central portion of the conductor to 5% or more, the conductor can be efficiently formed into a flat shape. When the flat conductor is deformed by applying force to form the low flatness portion, the wire deformed by a deformation rate of 5% or more remains in the central portion of the conductor even in the low flatness portion.

[0018] It is preferable that the void ratio, which is the proportion of voids not occupied by the strands in the area of ​​the region surrounded by the inner circumference of the insulating coating in the cross section, is larger in the low flat portion than in the flat portion. The voids formed around the conductor and between the strands assist the conductor in flexible bending. The low flat portion has larger voids than the flat portion, which increases the flexibility of the low flat portion. When a force is applied to an insulated electric wire in which a conductor is formed into a flat shape to deform the conductor to form a low flat portion, the conductor is deformed into a shape with a low flatness in a space whose perimeter is determined by the inner circumference of the insulating coating, and the proportion of voids in the conductor increases.

[0019] In the cross section, the difference in the outer periphery of the conductor between the flat portion and the low flat portion may be 5% or less of the outer periphery of the conductor in the flat portion. When a force is applied to an insulated electric wire in which a conductor is molded into a flat shape to deform the wire and form a low flat portion, the change in the outer periphery of the conductor is limited by the inner periphery of the insulating coating. Thus, an insulated electric wire in which the difference in the outer periphery of the conductor between the flat portion and the low flat portion is suppressed to 5% or less of the outer periphery of the conductor in the flat portion can be easily manufactured using an insulated electric wire in which the entire conductor is molded into a flat shape as a raw material.

[0020] The insulating coating may be in close contact with the outer periphery of the conductor in both the flat portion and the low flat portion. By having the insulating coating in close contact with the outer periphery of the conductor, when heat is generated by passing electricity through the conductor, the efficiency of heat dissipation through the insulating coating can be increased in both the flat portion and the low flat portion. In particular, for an insulated electric wire having a large conductor cross-sectional area and used for applying a large current, heat dissipation during current passage is important. When a low flat portion is formed by applying force to an insulated electric wire in which the entire conductor is molded into a flat shape to deform it, a gap is likely to be formed between the conductor and the insulating coating in the low flat portion. However, the insulating coating can be adhered to the outer periphery of the conductor by heating a portion including the formed low flat portion and softening or melting the insulating coating once.

[0021] In this case, the insulation electric wireThe insulated wire may have a transition region between the flat portion and the low flat portion, where the outer shape of the conductor changes with a continuous slope, and the insulating coating may be in close contact with the outer periphery of the conductor even in the transition region. This can promote heat dissipation during current flow, including the transition region between the flat portion and the low flat portion. In addition, since the shapes of the conductor and the insulating coating change gradually between the flat portion and the low flat portion, loads and stresses are less likely to be generated on the conductor and the insulating coating compared to when the shapes change suddenly in a step shape. Furthermore, by utilizing the transition region, it is easy to position an external member, such as a rubber stopper for water blocking, and place it in close contact with the insulated wire.

[0022] Alternatively, in the cross section of the low flat portion, the outer regions of the conductor may be defined as a width direction outer conductor region and a height direction outer conductor region, respectively, along the directions corresponding to the width direction and height direction of the flat shape, and a larger gap may be formed between the conductor and the insulating coating in the width direction outer conductor region than in the height direction outer conductor region. When a low flat portion is formed by applying force to an insulated electric wire in which a conductor is formed into a flat shape and deforming it, a gap is likely to be formed between the conductor and the insulating coating in the width direction outer conductor region in the low flat portion, since the width direction dimension of the conductor is reduced. When the insulating coating is not adhered by heating, the gap formed between the conductor and the insulating coating when the conductor is deformed remains as it is. This gap, together with the gap formed between the wires, can contribute to improving the flexibility of the low flat portion.

[0023] The insulated wire may have a plurality of the flat portions along the axial direction, and the low flat portion may be provided between two of the flat portions. In this manner, the insulated wire having the low flat portion provided in the middle portion in the axial direction is suitable for use in applications where the middle portion is bent into a complex shape for three-dimensional wiring or the like.

[0024] The insulated wire according to the second embodiment of the present disclosure is manufactured by compressing a conductor formed by twisting together a number of strands into a flat shape, coating the outer periphery with an insulating coating to form an insulated wire, and then applying force from the outside to the inside in the width direction of the flat shape in a certain region along the axial direction of the insulated wire to reduce the flatness of the conductor, thereby forming a low-flatness portion, and leaving the area other than the low-flatness portion as a flat portion.

[0025] In the insulated electric wire according to the second embodiment, the difference in flexibility in the low flat portion depending on the bending direction is smaller than that in the flat portion, and the low flat portion can be used for bending into a complex shape such as a three-dimensional wiring. By utilizing the bending flexibility in each direction of the low flat portion and the bending flexibility and space saving in the height direction of the flat portion, an insulated electric wire excellent in both bending freedom and space saving can be obtained. By forming an insulating coating on the outer periphery of a conductor molded into a flat shape and then applying a force to the insulated electric wire to deform it and form a low flat portion, an insulated electric wire having such a low flat portion and a flat portion integrally therewith can be easily formed. In addition, the low flat portion can be freely formed at any position on the insulated electric wire required according to a specific wiring location, etc.

[0026] The wire harness according to the present disclosure includes the insulated electric wire according to the present disclosure. As described above, the insulated electric wire according to the present disclosure exhibits high bending flexibility in all directions, including the width direction of the flat shape, at the low flat portion, and therefore the wire harness can be suitably applied to a location where the insulated electric wire needs to be bent into a complex shape, such as a three-dimensional wiring, by utilizing the low flat portion.

[0027] [Details of the embodiment of the present disclosure] In the following, an insulated electric wire and a wire harness according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this specification, with respect to the shape of each part of the insulated electric wire, concepts indicating the shape and arrangement of members, such as straight, parallel, vertical, etc., include errors from the geometric concepts within the range permitted for this type of insulated electric wire, such as deviations of approximately ±15% in length and approximately ±15° in angle. In this specification, the cross section of an insulated electric wire or a conductor refers to a cross section cut perpendicular to the axial direction (longitudinal direction), unless otherwise specified.

[0028] <Outline of insulated wire> Fig. 1A shows a perspective view of an insulated electric wire 1 according to an embodiment of the present disclosure. Fig. 1B and Fig. 1C show simplified cross-sectional views taken along lines AA and BB in Fig. 1A, respectively. Fig. 2 and Fig. 3 show detailed cross-sections of a flat portion corresponding to Fig. 1B and a low flat portion corresponding to Fig. 1C, respectively.

[0029] The insulated wire 1 according to this embodiment has a conductor 11 and an insulating coating 13. The conductor 11 is configured as a stranded wire in which a plurality of strands 12 are stranded together. The insulating coating 13 covers the entire outer circumference of the conductor 11. The insulated wire 1 has a flat portion 20 and a low flat portion 30 along the axial direction (x direction). The flat portion 20 and the low flat portion 30 are integrally continuous along the axial direction of the insulated wire 1. That is, the strands 12 constituting the conductor 11 are integrally continuous with each other between the flat portion 20 and the low flat portion 30. In addition, the insulating coating 13 covering the conductor 11 is also integrally continuous with each other between the flat portion 20 and the low flat portion 30.

[0030] In the flattened portion 20, the outer shape of the conductor 11 in the cross section is flat. Here, the outer shape of the conductor 11 is flat, which means that the width w, which is the length of the longest straight line among the straight lines that cross the cross section parallel to the sides or diameters that constitute the cross section and include the entire cross section, is greater than the height h, which is the length of the straight line that is perpendicular to the straight line and includes the entire cross section. The cross section of the conductor 11 may have any specific shape as long as it is flat, but in this embodiment, the cross section of the conductor 11 has a shape that can be approximated to a rectangle. Examples of flat shapes other than a rectangle include an ellipse, an oval, and an oval (a shape in which a circular arc is joined to both sides of a rectangle). From the viewpoint of improving space saving, the aspect ratio w / h of the flattened portion 20 is preferably, for example, 2 or more and 6 or less. Hereinafter, in the entire area of ​​the insulated wire 1 including the low flatness portion 30, the directions corresponding to the width direction and height direction of the flat shape of the flatness portion 20 will be referred to as the width-equivalent direction (y direction) and the height-equivalent direction (z direction), respectively.

[0031] In the low flat portion 30, the conductor 11 has a shape with a smaller flatness in cross section than the flat portion 20. Here, the low flatness of the conductor 11 means that the aspect ratio w / h in the cross section of the conductor 11 is small and the cross section shape is low in flatness. The specific shape of the low flat portion 30 is not particularly limited, and examples include shapes that can be approximated to figures with no anisotropy or low anisotropy, such as a square, a circle, a hexagon, etc., as well as shapes that can be approximated to a rectangle, an ellipse, an oval, etc. with a smaller aspect ratio w / h than the flat portion 20. The smaller the flatness of the low flat portion 30, the better, and a shape that has a cross section that can be approximated to a circle or a square with an aspect ratio w / h of 1 is most preferable. However, if the aspect ratio w / h of the low flat portion 30 is set to, for example, 2 or less, the effect of increasing the flexibility (bending property) of bending in the width direction, which will be described later, can be sufficiently obtained. Moreover, the aspect ratio w / h of the low flat portion 30 may be set to be approximately 20% or more and 70% or less of the aspect ratio w / h of the flat portion 20. In the low flat portion 30, it is preferable that the dimension w in the width-equivalent direction is not smaller than the dimension h in the height-equivalent direction (w / h ≧ 1). In other words, it is preferable that the low flat portion 30 does not have a vertically elongated cross-sectional shape. However, this does not prevent the low flat portion 30 from having a vertically elongated cross-sectional shape, and in that case, it is preferable that the aspect ratio h / w of the low flat portion 30 is smaller than the aspect ratio w / h of the flat portion 20. Furthermore, from the viewpoint of increasing the flexibility of the low flat portion 30, the aspect ratio h / w of the low flat portion 30 may be set to be 2 or less, similar to the aspect ratio w / h in the case of the horizontally elongated shape described above. Furthermore, the aspect ratio h / w of the low flat portion 30 may be set to about 20% or more and 70% or less of the aspect ratio w / h of the flat portion 20.

[0032] In this way, the insulated electric wire 1 having the flat portion 20 and the low flat portion 30 integrally therewith can be suitably manufactured from a raw flat electric wire obtained by deforming the conductor 11 into a flat shape. The raw flat electric wire can be manufactured by compressing the conductor 11 having a circular cross section, which is formed by twisting a plurality of strands 12, into a flat shape, and covering the outer periphery of the conductor 11 with an insulating coating 13. In this case, the compression of the conductor 11 can be suitably performed by compressing it from both sides in the height direction and optionally from both sides in the width direction using a roller, as described in Patent Documents 3 to 5. The insulating coating 13 is preferably formed on the outer periphery of the compressed conductor 11 by extrusion molding of a resin composition. In a part of the raw flat electric wire obtained in this way along the axial direction, specifically in a region where the low flat portion 30 is to be formed, a force is applied from the outside of the raw flat electric wire toward the inside along the width direction (y direction) to deform the conductor 11. The application of force reduces the width dimension of the conductor 11, and the flatness of the conductor 11 decreases. This operation allows the low flatness portion 30 to be formed. The force can be applied manually or by processing using a tool such as a hammer, or an apparatus such as a molding die or press. The force applied to the conductor 11 at this time is preferably smaller than the force applied to flatten the conductor 11 when forming the raw flat electric wire. In the raw flat electric wire, the areas other than the areas where the low flatness portion 30 is formed by the application of force are left as flatness portions 20.

[0033] In the insulated electric wire 1 according to the present embodiment, the flat portion 20 has a flat shape, so that it is easy to arrange the wire in a narrow space and to arrange other members above and below it, and thus a high space saving can be achieved. In addition, since the conductor 11 is made of a twisted wire, the insulated electric wire 1 can be flexibly bent in the height equivalent direction. However, in the flat portion 20, due to its flat shape, the insulated electric wire 1 can be bent with high flexibility in the height equivalent direction (z direction; flat direction), but the bending flexibility in the width equivalent direction (y direction; edgewise direction) is lower than the bending flexibility in the height equivalent direction. In contrast, in the low flat portion 30, since the flatness of the cross-sectional shape of the conductor 11 is low, the difference in flexibility in bending in each direction is small, and the low flat portion 30 exhibits high bending flexibility not only in the height equivalent direction but also in the width equivalent direction. Therefore, in the insulated electric wire 1 according to the present embodiment, it is easy to bend and deform the low flat portion 30 into a complex shape. Therefore, by utilizing the low flat portion 30, the insulated wire 1 can be suitably routed in an automobile or the like, which requires bending into a complex shape, such as three-dimensional routing.

[0034] In this embodiment, the positions and number of the low flat portions 30 in the axial direction of the insulated electric wire 1 are not particularly limited, and the low flat portions 30 may be formed at any positions where bending into a complex shape such as three-dimensional wiring is expected. As described above, the low flat portions 30 can be formed by simply applying a force that deforms the conductor 11 from the outside of the insulating coating 13 to the raw flat electric wire. Therefore, various insulated electric wires 1 in which the low flat portions 30 are required at different positions can be easily manufactured using a common raw flat electric wire. As a preferred embodiment, a plurality of flat portions 20 are formed along the axial direction of the insulated electric wire 1, and the low flat portion 30 is formed between two flat portions 20. Furthermore, a preferred embodiment is one in which the flat portions 20 are formed at both ends of one insulated electric wire 1, and the low flat portion 30 is formed between the flat portions 20. Then, at both ends of the insulated wire 1 where connection points to equipment, etc. are provided and the wiring path is not particularly complicated, the high space-saving effect provided by the flat sections 20 can be utilized, while at the middle part of the insulated wire 1, the high flexibility in each direction of the low flat sections 30 can be utilized to accommodate wiring along a complex path.

[0035] In the insulated wire 1 according to the present embodiment, it is preferable to have a transition region 40 between the flat portion 20 and the low flat portion 30, where the outer shape of the conductor 11 changes with a continuous incline (tapered shape), rather than a discontinuous step-like change in the outer shape between the flat portion 20 and the low flat portion 30. This makes it possible to prevent a large load or stress from being generated in the conductor 11 due to a sudden change in the outer shape of the conductor 11 between the flat portion 20 and the low flat portion 30.

[0036] In the insulated wire 1 according to this embodiment, the material, wire diameter, and conductor cross-sectional area of ​​the strands 12 constituting the conductor 11 are not particularly limited. However, from the viewpoint of enhancing the effect of improving bending flexibility in each direction by forming the low flattened portion 30, it is preferable to use a conductor 11 having a relatively large conductor cross-sectional area. From this viewpoint, it is preferable to use aluminum or an aluminum alloy as the material for the conductor 11, which has a low electrical conductivity compared to copper and copper alloys and therefore is often made to have a large conductor cross-sectional area. In addition, the conductor cross-sectional area is preferably 10 mm 2More than 50mm 2 Above 100mm 2 The outer diameter of the wire 12 constituting the conductor 11 is preferably 0.3 or more. mm An example of the range is 1.0 mm or less.

[0037] The insulated electric wire 1 according to the present embodiment may be used alone or as a constituent member of the wire harness according to the embodiment of the present disclosure. The wire harness according to the embodiment of the present disclosure includes the insulated electric wire 1 according to the above embodiment. The wire harness may include a plurality of the insulated electric wires 1, or may include other types of insulated electric wires in addition to the insulated electric wire 1.

[0038] <Deformation rate of wire> In the insulated wire 1 according to this embodiment, the deformation ratio of the wires 12 in the cross section has a non-uniform distribution, which is also related to the manufacturing method as described above. Here, the deformation ratio of the wires 12 is an index showing how much the cross-sectional shape of a certain wire 12 deviates from a circular shape. For a certain wire 12 actually included in the conductor 11, if the length of the longest straight line crossing the cross section is defined as the major axis A and the diameter of a circle having the same area as the cross-sectional area of ​​the wire 12 is defined as the circle diameter R, the deformation ratio D of the wire 12 can be expressed by the following formula (1). D = (A R ) / R × 100% (1) When evaluating the deformation rate of the wires 12 at some parts of the cross section of the conductor 11, such as the widthwise end or center, it is preferable to estimate the deformation rate as an average value for multiple wires 12 included in a region covering a certain area, such as regions R1 to R3 shown in Figures 2 and 3, in order to reduce the influence of variations in the deformation of the wires 12. For example, a region surrounded by a rectangle having sides with a length of about 10 to 30% of the width w of the conductor 11 or a circle having a diameter of the same length may be set.

[0039] In the insulated electric wire 1 according to the present embodiment, as shown in Figs. 2 and 3, in both the flat portion 20 and the low flat portion 30, the deformation rate of the wires 12 is smaller in the widthwise end portions (regions R2) that are the outer (both ends) regions along the width direction (y direction) of the outer periphery facing the outer periphery of the conductor 11 than in the central portion (region R1) located inside the outer periphery. That is, in the flat portion 20 and the low flat portion 30, the wires 12 at the widthwise end portions have a shape closer to a circle than the wires 12 at the central portion. Note that Figs. 2 and 3 show the deformation of each wire 12 in a schematic manner, and the wires 12 are shown deformed into a flattened ellipse in the central portion of the conductor 11, etc., but in the actual conductor 11, the wires 12 may be deformed into not only such a flat shape but also into an irregular shape like the wires included in the cross-sectional images of Figs. 6A, 6B, etc.

[0040] As described above, when the insulated electric wire 1 according to the present embodiment is formed from a raw flat electric wire including a stranded conductor formed into a flat shape, the conductor 11 included in the raw flat electric wire is deformed into a flat shape by applying a gentle force to the stranded wire using a roller, and as described in Patent Documents 3 to 5, the deformation rate of the strands 12 is smaller at the outer periphery, particularly at the widthwise ends, than at the center. When the insulated electric wire 1 according to the present embodiment is manufactured from this raw flat electric wire, the flat portion 20 substantially inherits the structure of the conductor 11 in the raw flat electric wire. In the low flat portion 30, the outer shape of the conductor 11 as a whole is deformed into a shape with a low degree of flatness, but the shape of each strand 12 is almost unchanged. Therefore, the distribution of the deformation rate of the strands 12 generated in the raw flat electric wire is inherited almost as it is in the low flat portion 30. Therefore, in the flat portion 20 and the less flat portion 30 of the insulated electric wire 1 according to this embodiment, the deformation rate of the wires 12 is smaller at the width direction ends than at the central portion, similar to the raw flat electric wire.

[0041] In the low flat portion 30 or the flat portion 20, the specific ratio of the deformation rate of the wires 12 at the widthwise end portion and the center portion is not particularly limited, but the smaller the deformation rate of the wires 12 at the widthwise end portion, the more preferable. For example, the ratio of the deformation rate of the wires 12 at the widthwise end portion to the deformation rate of the wires 12 at the center portion (deformation rate at widthwise end portion / deformation rate at center portion × 100%) is preferably 70% or less, and more preferably 50% or less. In addition, it is preferable that the deformation rate of the wires 12 at the widthwise end portion is 10% or less, and more preferably 5% or less. The smaller the deformation rate of the wires 12 at the widthwise end portion, the more preferable, and no lower limit is set.

[0042] The deformation rate of the wires 12 in the center portion is not particularly limited, but is preferably 20% or less, and more preferably 10% or less, from the viewpoint of avoiding application of a load to the wires 12 due to excessive deformation. However, in the raw flat electric wire which becomes the flat portion 20 as it is, from the viewpoint of effectively forming the conductor 11 into a flat shape, the deformation rate of the center portion is preferably 5% or more in both the flat portion 20 and the low flat portion 30.

[0043] Furthermore, in the cross section of the low flat portion 30 or the flat portion 20, the deformation rate of the wires 12 at the width direction end is preferably smaller than that of not only the central portion but also the height direction end (region R3) that corresponds to the outer (both ends) region along the height equivalent direction (z direction) of the outer periphery of the conductor 11. The specific ratio of the deformation rates of the wires 12 at the width direction end and the height direction end is not particularly limited, but the ratio of the deformation rate of the wires 12 at the width direction end to the deformation rate of the wires 12 at the height direction end (deformation rate at width direction end / deformation rate at height direction end×100%) is preferably 70% or less, or even 50% or less, similar to the ratio to the deformation rate of the central portion described above. height The relationship between the deformation rates of the wires 12 at the axial ends and the central portion is not particularly limited.

[0044] As described above, the insulated wire 1 according to the present embodiment can be easily formed by deforming a raw flat electric wire in which the insulating coating 13 is formed on the outer periphery of the conductor 11, which is formed into a flat shape over the entire axial direction, in a partial region in the axial direction. On the other hand, an insulated electric wire in which a flat cross-sectional region and a region with a low cross-sectional flatness coexist can also be manufactured by a method in which a stranded conductor having a circular cross section is deformed into a flat shape only in a partial region in the axial direction and then the insulating coating 13 is formed on the outer periphery of the stranded conductor. However, in this case, since the region with a low cross-sectional flatness is not deformed by application of force to the conductor 11, the wire 12 is maintained in a state in which it is not deformed from a substantially circular shape over the entire cross section including the central portion and the outer periphery. In this way, when only a partial region of the conductor 11 is deformed into a flat shape and then the insulating coating 13 is formed, the position where the region with a low cross-sectional flatness is provided along the axial direction of the insulated electric wire 1 can be determined by the conductor 11. 11 This is different from the insulated wire 1 according to the present embodiment, in which the low flat portion 30 can be formed at any position afterwards.

[0045] <Relationship between conductor and insulating coating> As described above, when the insulated wire 1 according to the present embodiment having the flat portion 20 and the low flat portion 30 is formed using a raw flat electric wire in which the insulating coating 13 is provided on the outer periphery of the conductor 11 formed into a flat shape, a gap that is not occupied by the wire 12 is often formed between the conductor 11 and the insulating coating 13 in the low flat portion 30 as shown in FIG. 4. This is because when a force is applied to the conductor 11 from the outside of the raw flat electric wire to form the low flat portion 30, the conductor 11 is deformed, but the length of the inner circumference of the insulating coating 13 remains almost unchanged. In response to applying a force from the outside to the inside in the width equivalent direction (y direction) to the conductor 11 and compressing the conductor 11 in the width equivalent direction, a larger gap is likely to be formed in the width direction outer conductor region R4 that corresponds to the region outside the conductor 11 along the width equivalent direction than in the height direction outer conductor region R5 that corresponds to the region outside the conductor 11 along the height equivalent direction. That is, the distance between the conductor 11 and the inner peripheral surface of the insulating coating 13 is likely to be greater in the width direction outer-conductor region R4 than in the height direction outer-conductor region R5, and gaps are unevenly distributed in the width direction outer-conductor region R4. Not only in the low flat portion 30, but also in the boundary between the low flat portion 30 and the flat portion 20, gaps may be unevenly distributed in the width direction outer-conductor region R4.

[0046] The insulated wire 1 according to the present embodiment may be used in a state in which the insulating coating 13 is not in close contact with the outer periphery of the conductor 11 in the low flat portion 30 as shown in FIG. 4, and a gap is generated between the conductor 11 and the insulating coating 13, particularly in the widthwise outer conductor region R4. As will be described in detail later, the gap between the conductor 11 and the insulating coating 13 contributes to increasing the flexibility of the low flat portion 30. However, the insulating coating 13 may be heated in a region including the low flat portion 30 while the conductor 11 of the raw flat electric wire is being deformed to form the low flat portion 30, or after the conductor 11 is deformed to form the low flat portion 30, to soften or melt the insulating coating 13. In the softened or melted state, the insulating coating 13 can be brought into close contact with the outer periphery of the conductor 11 by applying a force pressing the insulating coating 13 against the conductor 11 using a mold or the like as appropriate. 2 and 3, the insulating coating 13 comes into close contact with the outer periphery of the conductor 11 in both the flat portion 20 and the low flat portion 30. By bringing the insulating coating 13 into close contact with the conductor 11 and preventing an air layer from being interposed between the insulating coating 13 and the conductor 11, heat generated when electricity is passed through the conductor 11 can be efficiently dissipated to the outside via the insulating coating 13.

[0047] When the insulated wire 1 has a transition region 40 between the flat portion 20 and the low flat portion 30, where the outer shape of the conductor 11 changes with a continuous slope, it is preferable to make the insulating coating 13 adhere to the outer periphery of the conductor 11 in the transition region 40 as well as the insulating coating 13 adhere to the outer periphery of the conductor 11 in the low flat portion 30, so that the outer shape of the insulated wire 1 as a whole, including the insulating coating 13, changes with a continuous slope. This makes it possible to suppress the application of a large load and the generation of stress due to a sudden change in the outer shape not only of the conductor 11 but also of the insulating coating 13 in the region between the flat portion 20 and the low flat portion 30. Furthermore, since the flat portion 20 and the low flat portion 30 are connected by a smooth slope as a whole insulated wire 1, it is easy to arrange an external member, such as a rubber stopper for water blocking, in a state where the member is positioned at a predetermined position along the axial direction of the insulated wire 1 and adhered to the outer periphery of the insulated wire 1.

[0048] As described above, when a force is applied from the outside of the raw flat electric wire to form the low flat portion 30, the conductor 11 is deformed, but the inner circumferential length of the insulating coating 13 remains almost unchanged. This results in the feature that gaps between the conductor 11 and the insulating coating 13 are unevenly distributed in the width-direction outer-conductor region R4, and in addition, the feature that the outer circumferential length of the cross section of the conductor 11 is unlikely to differ between the low flat portion 30 and the flat portion 20. This is because, when the conductor 11 is deformed to form the low flat portion 30, the outer circumferential length of the conductor 11 is limited by the inner circumferential length of the insulating coating 13, so it is difficult to significantly change the outer circumferential length of the conductor 11. In the cross section of the obtained insulated electric wire 1, the difference in the outer circumferential length of the conductor 11 between the flat portion 20 and the low flat portion 30 is, for example, 5% or less of the outer circumferential length of the conductor 11 in the flat portion 20. That is, assuming that the outer periphery of the conductor 11 in the flat portion 20 is L1 and the outer periphery of the conductor 11 in the less flat portion 30 is L2, the periphery difference ratio ΔL expressed by the following formula (2) is 5% or less. ΔL=|L1-L2| / L1 (2) The outer periphery of the conductor 11 may be evaluated as the length of the contour line that smoothly connects the contours of the wires 12 arranged at the outermost periphery of the conductor 11 in a cross section. The state in which the difference in the outer periphery of the conductor 11 between the flat portion 20 and the low flat portion 30 is small, such as when the periphery difference ratio ΔL is 5% or less, is maintained even when the insulating coating 13 is heated in the low flat portion 30 to be brought into close contact with the outer periphery of the conductor 11. When the insulating coating 13 is not heated to be brought into close contact with the conductor 11, the inner periphery length of the insulating coating 13 may be used to evaluate the periphery difference ratio ΔL instead of the outer periphery lengths L1 and L2 of the conductor 11.

[0049] <Porosity of insulated wire> In the insulated wire 1 according to the present embodiment, the void ratio in the cross section is preferably larger in the low flatness portion 30 than in the flatness portion 20. Here, the void ratio refers to the ratio of the area of ​​the gap not occupied by the wires 12 to the area of ​​the region surrounded by the inner periphery of the insulating coating 13 in the cross section of the insulated wire 1.

[0050] If many gaps are formed in the cross section of the insulated wire 1 and the void ratio is large, the movement of the wires 12 into the gaps during bending of the conductor 11 assists in flexible bending of the insulated wire 1. Thus, by making the low flatness portion 30 have a larger void ratio than the flatness portion 20, in addition to the effect of the low flatness portion 30 having a cross-sectional outer shape, the flexibility of bending in each direction is further enhanced. As a result, it becomes easier to bend the insulated wire 1 into a complex shape using the low flatness portion 30.

[0051] As described above, when the low flat portion 30 is formed by applying a force from the outside to the inside in the width direction to deform the conductor 11 in a part of the raw flat electric wire in which the insulating coating 13 is provided on the outer periphery of the conductor 11 formed into a flat shape, the void ratio is easier to increase in the low flat portion 30 than in the flat portion 20. As described above about the relationship between the conductor 11 and the insulating coating 13, the inner periphery length of the insulating coating 13 in the cross section does not change much before and after the deformation, and the change in the outer periphery length of the conductor 11 is limited by the inner periphery length of the insulating coating 13. However, if the outer periphery length is the same, the area of ​​the area surrounded by the outer periphery of a figure with a low degree of flatness is larger than that of a figure with a high degree of flatness. In other words, there is room to increase the area of ​​the area surrounded by the outer periphery of the conductor 11 in the low flat portion 30 compared to the flat portion 20. Since the area occupied by the wires 12 in the region surrounded by the outer periphery of the conductor 11 is constant, when the area of ​​the region surrounded by the outer periphery of the conductor 11 as a whole increases in the low flat portion 30, the area occupied by voids inside the region, that is, the void ratio, increases. For this reason, the low flat portion 30 is more likely to have a larger cross-sectional void ratio than the flat portion 20 after being deformed from the raw flat electric wire.

[0052] As described above regarding the relationship between the conductor 11 and the insulating coating 13, in the state in which the conductor 11 of the raw flat electric wire is deformed to form the low flat portion 30, voids are likely to be formed between the outer periphery of the conductor 11 and the insulating coating 13 in the low flat portion 30, and the voids are likely to be unevenly distributed, particularly in the width-direction outer conductor region R4. In this way, the voids formed on the outer side of the conductor 11 also contribute to improving the flexibility of the conductor 11 due to the movement of the strands 12. Therefore, it is sufficient that the void ratio (total void ratio) of the entire region surrounded by the inner periphery of the insulating coating 13 in the cross section of the insulated electric wire 1, including the voids formed on the outer periphery of the conductor 11, is higher in the low flat portion 30 than in the flat portion 20. However, the voids formed inside the outer periphery of the conductor 11, that is, the voids formed between the strands 12 constituting the conductor 11, are more effective in improving the bending flexibility of the conductor 11. Therefore, it is even more preferable if the void ratio (internal void ratio) when only the voids formed inside the outer periphery of the conductor 11 are considered is larger in the low flat portion 30 than in the flat portion 20. The distribution of voids inside the outer periphery of the conductor 11 and the intra-conductor void ratio due to the contribution of these voids are substantially maintained even after the insulating coating 13 is bonded to the conductor 11 by heating.

[0053] The specific porosity (total porosity; the same applies in this paragraph) in the low flat portion 30 is not particularly limited. However, the ratio of the porosity of the low flat portion 30 to the porosity of the flat portion 20, that is, the porosity ratio Vr expressed by the following formula (3) where the porosity of the flat portion 20 is V1% and the porosity of the low flat portion 30 is V2%, may be 1.2 or more. Vr = V2 / V1 (3) Furthermore, the void ratio Vr is preferably 1.5 or more, or 2.0 or more. The void ratio value (V2) in the low flat portion 30 is preferably 35% or more, further preferably 40% or more, or 45% or more. This makes it easier to ensure high flexibility in the low flat portion 30. In the flat portion 20, the void ratio (V1) is preferably 10% or more from the viewpoint of ensuring bending flexibility in the height direction. From the viewpoint of flexibility, there is no particular upper limit set for the void ratios (V1, V2), but from the viewpoint of stably maintaining the outer shape of the specified conductor 11 in each of the flat portion 20 and the low flat portion 30, it is preferably set to approximately 50% or less. EXAMPLES

[0054] Examples are shown below, but the present invention is not limited to these examples.

[0055] [1] Conductor shape and bending flexibility of insulated wire First, the bending flexibility was compared between a flat electric wire having a low flat portion and a flat electric wire not having a low flat portion.

[0056] (Sample preparation) First, a flat electric wire was prepared. First, a stranded wire with a circular cross section was prepared by twisting together aluminum alloy wires, and the stranded wire was compressed into a flat shape using a roller to produce a conductor. The stranded wire had a conductor cross section of 130 mm 2 The wire diameter was 0.42 mm. The aspect ratio of the flat shape w / h was approximately 3. An insulating coating was formed on the outer periphery of the produced conductor by extrusion molding. Cross-linked polyethylene was used as the constituent material of the insulating coating, and the thickness of the insulating coating was 2 mm.

[0057] As one of the samples, the flat electric wire prepared above was used as it was. As another sample, a low-flattened electric wire was prepared from the flat electric wire prepared above. That is, a force was applied from the outside to the inside in the width direction of the flat shape in a region of the flat electric wire that was 6 cm long along the axial direction, thereby reducing the flatness of the flat shape of the conductor, thereby forming a low-flat portion. The aspect ratio w / h of the conductor in the low-flat portion was about 1. After forming the low-flat portion, the part of the electric wire including the low-flat portion was heated to adhere the insulating coating to the conductor.

[0058] (Evaluation method) The flexibility of each of the insulated wires produced above was evaluated. In the evaluation, as shown in FIG. 5, a weight T2 weighing 500 g was attached to one end of the insulated wire 1 cut to a length of 50 cm, and the wire was supported horizontally at a position 25 cm from the other end with a fulcrum T1 (indicated by the dashed line in the figure). At this time, the width direction (y direction) of the flattened shape of the insulated wire 1 was set in the direction of gravity, so that the insulated wire 1 was bent in the width direction by the gravity of the weight T2. For the low-flattened wires, the fulcrum T1 was set in the center of the area where the low-flat portion was formed. For each insulated wire 1, the end to which the weight T2 was attached was set in the direction of gravity. T2 Weight To the force Therefore, the distance d1 hanging down from the horizontal position was measured.

[0059] (Evaluation Results) Table 1 below shows the sagging distance d1 of the end for flat wires and low-flattened wires.

[0060] [Table 1]

[0061] According to Table 1, the sagging distance of the end caused by the weight is more than twice as long for the low-flattened electric wire as for the flattened electric wire. This means that the low-flattened electric wire has higher bending flexibility in the width direction than the flattened electric wire. Although the low-flattened electric wire only has a reduced flatness in a portion of the flattened electric wire, it shows a high effect in improving bending flexibility in the width direction.

[0062] [2] Deformation of wires in a conductor Next, the deformation of the wires that make up the conductor was compared between the flat and low flat sections.

[0063] (Sample preparation) In the same manner as in the above test [1], a low-flattened electric wire was produced by forming a low-flattened portion in the middle of the axial direction of the flat electric wire. However, after forming the low-flattened portion, the insulation coating was not heated to adhere to the conductor. The cross-sectional area of ​​the conductor was 130 mm 2 The aspect ratio w / h of the conductor was approximately 3 in the flat portion and approximately 1 in the low flat portion. The obtained low flattened electric wire was embedded and fixed in acrylic resin, and cross-sectional samples were prepared by cutting perpendicularly to the axial direction in both the flat portion and the low flat portion.

[0064] (Evaluation method) Cross-sectional samples of the flat and low flat sections were observed under a microscope to evaluate the deformation of the wires at each part of the cross section. In particular, for the low flat section, the deformation rate of the wires was quantitatively evaluated at representative locations using microscopic images of the cross section. In other words, the wire diameters were measured for the wires contained in a specified area, and the deformation rate (D) of the wires was estimated according to the above formula (1). The average value of the deformation rate of the wires obtained within each area was recorded.

[0065] (Evaluation Results) 6A and 6B show images of the cross sections of the flat and low flat parts, respectively. Table 2 below shows the results of evaluating the wire deformation rate of each part of the low flat part.

[0066] [Table 2]

[0067] First, looking at the cross section of the flattened portion in Fig. 6A, the wires in the central portion of the conductor shown as region R1 are significantly deformed from their circular shape, whereas the wires in the widthwise end portion shown as region R2 maintain a shape close to circular, and it is clear that the deformation rate of the wires is smaller in the widthwise end portion than in the central portion. Furthermore, many wires are also deformed from their circular shape in the heightwise end portion shown as region R3, and it is clear that the deformation rate of the wires in the widthwise end portion is smaller than that in the heightwise end portion. It is believed that the wires in the widthwise end portion were not significantly deformed from their circular shape by gently deforming the entire conductor into a flat shape using a roller.

[0068] Next, looking at the cross section of the low flatness portion shown in Figure 6B, we can see that, like the flatness portion, in the center of the conductor, shown as region R1, the strands have been deformed from circular to significantly flattened, whereas in the widthwise ends, shown as region R2, the strands retain a shape that can be considered nearly circular, and it is clear that the deformation rate of the strands is smaller at the widthwise ends than at the center. This is further shown clearly in the results of Table 2, which quantitatively analyzes the deformation rates of the strands in regions R1 and R2. The value of the strand deformation rate at the widthwise end R2 is , medium The deformation rate of the wire at the width direction end portion R2 is a small value of 5% or less, even in terms of absolute value.

[0069] Furthermore, in Fig. 6B, many wires are deformed from the circular shape at the height direction end shown as region R3, and it can be seen that the deformation rate of the wires at the width direction end is smaller than that at the height direction end. Also in Table 2, the deformation rate of the wires at the width direction end R2 is less than half the value at the height direction end R3.

[0070] From the above results, it is confirmed that the characteristic of the flat portion, in which the deformation rate of the wire at the widthwise ends of the conductor is smaller than the deformation rate at the center and the heightwise ends, is inherited in the low flat portion through deformation of the conductor due to the application of force from both sides in the width direction.

[0071] [3] Perimeter and void ratio in conductor (Sample preparation) In the same manner as in the above test [1], a low-flattened electric wire was produced by forming a low-flattened portion in the middle of the axial direction of the flat electric wire. However, after forming the low-flattened portion, the insulation coating was not heated to adhere to the conductor. mm 2 , 60 mm 2 , 130 mm 2 The aspect ratio w / h of the conductor was about 3 for the flat part and about 1 for the low flat part. The thickness of the insulating coating was about 15 mm 2 The thickness was 1 mm for the sample of the first type and 2 mm for the other two types. As in the case of test [2], cross-sectional samples were prepared for both the flat and low-flat parts of each insulated wire produced. Note that the flat wire used as the raw material for the low-flat wire in this test [3] has a higher adhesion of the insulation coating to the conductor than the one used in test [2].

[0072] (Evaluation method) Microscopic images were taken of each cross-sectional sample, and the conductor's outer circumference and porosity were measured by image analysis. The conductor's outer circumference was measured by drawing a contour line in the image by smoothly connecting the conductor's outer circumference, and measuring the length of that contour line. The porosity was calculated as the percentage of the total area of ​​the area inside the insulating coating that was not occupied by the wires in the cross-sectional image.

[0073] (Evaluation Results) 7A to 7C show cross-sectional images of the flat and low flat parts of each insulated wire. mm 2 , 60 mm 2 , 130 mm 2For the case, the flat part is shown on the left and the low flat part on the right. Table 3 below summarizes the conductor circumference and porosity values ​​for the flat and low flat parts of each sample. For the conductor circumference, the circumference difference ratio ΔL calculated using formula (2) above is also shown. For the porosity, the porosity ratio Vr calculated using formula (3) above is also shown.

[0074] [Table 3]

[0075] 7A to 7C, the insulating coating is in close contact with the entire outer circumference of the conductor in both the flat and low flat portions. It can also be seen that in both samples, there are more gaps between the wires in the low flat portion than in the flat portion. The difference in the amount of gap between the low flat portion and the flat portion is particularly noticeable in samples with small conductor cross-sectional areas.

[0076] As can be seen from Table 3, the conductor outer perimeter is close to that of the flat and low flat parts for all samples. The perimeter difference ratio is also small, less than 5%. In other words, the conductor outer perimeter does not change much due to the flattening caused by the deformation of the conductor. This result is thought to be due to the fact that the low flat part is formed by the deformation of the conductor from the state where the outer perimeter of the flat conductor is covered with the insulating coating, and the change in the conductor outer perimeter is limited by the inner perimeter of the insulating coating. Note that the conductor outer perimeter listed in Table 3 indicates the length of the outline set by smoothly connecting the conductor outer perimeter as described above, and it has been confirmed that the perimeter calculated in this way is roughly consistent with the value obtained by binarizing the area inside the insulating coating in each sample image and analyzing the perimeter of the area corresponding to the wire.

[0077] Furthermore, according to Table 3, as can be seen from the cross-sectional images of Figures 7A to 7C, the void ratio is greater in the low flatness portion than in the flatness portion in all samples. The void ratio ratio is 2.0 or more in all samples. In other words, in the low flatness portion, the proportion of voids in the wire cross section is more than twice as large as in the flatness portion. This result reflects the fact that the smaller the flatness of a shape, the larger the area of ​​the region surrounded by an outer periphery of the same length. Note that for a conductor with a cross-sectional area of ​​130 mm 2 When the porosity of the flat parts of the samples was evaluated in the same manner for multiple locations of multiple individual samples, the error in the porosity value was a maximum of about 5%. This confirms that the difference in porosity between the flat and low flat parts shown in Table 3 is significant.

[0078] [4] Air gap between the conductor and the insulation Finally, we investigated the distribution of voids that occur between the conductor and the insulation coating due to the reduction in flatness caused by deformation of the flattened wire.

[0079] (Sample preparation) The samples used in the above test [2] were used in this test as they were. The samples were embedded in acrylic resin and fixed, and then cut at the flat and low flat parts and at the boundary between the flat and low flat parts to prepare cross-sectional samples.

[0080] (Evaluation method) Cross-sectional samples were prepared by cutting the insulated wire at each position, and microscopic images were taken of the samples. The porosity was then measured by image analysis in the same manner as in the above test [3].

[0081] (Evaluation Results) Figure 8A shows a photograph of the appearance of the insulated electric wire used as a sample. The photograph was taken from the direction opposite the flat surface of the flat portion, with the flat portion on the left and the low flat portion on the right. The positions at which the cross-sectional samples were obtained by cutting are also shown in the photograph. Figure 8B shows microscope images of the cross section at each position. The symbols shown above each image correspond to the cutting positions P1 to P5 shown in Figure 8A, with position P1 corresponding to the flat portion, position P2 corresponding to the boundary between the flat portion and the low flat portion, and positions P3 to P5 corresponding to the low flat portion. The cross-sectional images used to analyze the deformation rate of the wire in test [2] correspond to the cross sections at positions P1 and P5.

[0082] According to the cross-sectional image of Fig. 8B, in the cross sections of the boundary at position P2 and the low flat portions at positions P3 to P5, a larger gap is formed between the conductor and the insulating coating in the width direction, which corresponds to the horizontal direction of the image, than in the height direction. This uneven distribution of gaps in the width direction outside the conductor region corresponds to the fact that, when forming the low flat portion, a force is applied to the flat conductor from the outside in the width direction toward the inside, thereby reducing the dimensions of the conductor in the width direction. The uneven distribution of gaps in the width direction outside the conductor region is particularly noticeable at positions P3 and P4, which are close to the boundary, even within the low flat portion.

[0083] Furthermore, Table 4 below summarizes the void ratio in the cross section at each position. Due to differences in the adhesion between the conductor and the insulating coating in the flat electric wire used as the raw material, the void ratio values ​​obtained in Table 4 are greater than the values ​​shown in Table 3 above, both in the flat and low flat sections. However, in the results of Table 4, as in Table 3, the void ratio is greater in the low flat section than in the flat section. Even in the boundary section, a void ratio close to that of the low flat section is obtained.

[0084] [Table 4]

[0085] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0086] 1. Insulated wire 11 Conductor 12 Wire 13 Insulation coating 20 Flat part 30 Low flat part 40 Transition region d1 Drooping distance h Conductor height w conductor width x Axial direction of insulated wire y width equivalent direction z Height equivalent direction P1~P5 Cutting position R1 Central region R2 Width direction edge area R3 Height direction end area R4 Outside conductor area in width direction R5 Height direction outside conductor area T1 fulcrum T2 weight

Claims

1. A conductor in which a plurality of strands are twisted together; An insulated wire having an insulating coating that covers an outer periphery of the conductor, The wires constituting the conductor and the insulating coating are connected to each other, and have a flat portion and a low flat portion along an axial direction, an outer shape of the conductor in a cross section perpendicular to an axial direction of the insulated electric wire has a flat shape at the flat portion and a shape with a smaller flatness at the less flat portion than the flat portion; In the cross section of the conductor in both the flat portion and the low flat portion, the outer periphery of the conductor facing the outer periphery has a smaller deformation rate from the circular shape of the wire at the widthwise end portion corresponding to the widthwise outer side of the flat shape than at the central portion of the conductor and at the heightwise end portion corresponding to the heightwise outer side of the flat shape.

2. 2. The insulated wire according to claim 1, wherein a porosity, which is a ratio of voids not occupied by wires to an area of ​​a region surrounded by an inner periphery of the insulating coating in the cross section, is greater in the low flatness portion than in the flatness portion.

3. In the cross section of the low flat portion, the outer regions of the conductor along the directions corresponding to the width direction and height direction of the flat shape are defined as a width direction outer conductor region and a height direction outer conductor region, respectively, 3 . The insulated wire according to claim 1 , wherein a gap is formed between the conductor and the insulating coating in the width direction outer-conductor region, the gap being larger than a gap in the height direction outer-conductor region. 4 .

4. A conductor in which a plurality of strands are twisted together; An insulated wire having an insulating coating that covers an outer periphery of the conductor, The wires constituting the conductor and the insulating coating are connected to each other, and have a flat portion and a low flat portion along an axial direction, an outer shape of the conductor in a cross section perpendicular to an axial direction of the insulated electric wire has a flat shape at the flat portion and a shape with a smaller flatness at the less flat portion than the flat portion; In the cross section of the conductor in both the flat portion and the low flat portion, the deformation rate of the wire from a circular shape is smaller at a widthwise end portion of an outer periphery facing an outer periphery of the conductor, the widthwise end portion corresponding to an outer side of the flat shape in the width direction than at a central portion of the conductor, an insulating wire, wherein a porosity, which is the proportion of voids not occupied by wires to an area of ​​a region surrounded by an inner periphery of the insulating coating in the cross section, is greater in the low flatness portion than in the flatness portion.

5. A conductor in which a plurality of strands are twisted together; An insulated wire having an insulating coating that covers an outer periphery of the conductor, The wires constituting the conductor and the insulating coating are connected to each other, and have a flat portion and a low flat portion along an axial direction, an outer shape of the conductor in a cross section perpendicular to an axial direction of the insulated electric wire has a flat shape at the flat portion and a shape with a smaller flatness at the less flat portion than the flat portion; In the cross section of the conductor in both the flat portion and the low flat portion, the deformation rate of the wire from a circular shape is smaller at a widthwise end portion of an outer periphery facing an outer periphery of the conductor, the widthwise end portion corresponding to an outer side of the flat shape in the width direction than at a central portion of the conductor, In the cross section of the low flat portion, the outer regions of the conductor along the directions corresponding to the width direction and height direction of the flat shape are defined as a width direction outer conductor region and a height direction outer conductor region, respectively, the width-direction outer-conductor region has a gap formed between the conductor and the insulating coating that is larger than the height-direction outer-conductor region.

6. 6. The insulated wire according to claim 1, wherein a deformation rate from a circular shape of the wire at the low flatness portion is 70% or less at the width direction end portion compared to that at the central portion.

7. The insulated wire according to claim 1 , wherein a deformation rate of the wire from a circular shape in the low flatness portion is 5% or more in the central portion.

8. 8. The insulated wire according to claim 1, wherein in the cross section, a difference in outer periphery of the conductor between the flat portion and the less flat portion is 5% or less of a length of the outer periphery of the conductor in the flat portion.

9. The insulated wire according to claim 1 , wherein the insulating coating is in close contact with an outer periphery of the conductor in both the flat portion and the less flat portion.

10. 10. The insulated wire according to claim 9, wherein the insulated wire has a transition region between the flat portion and the low flat portion, where an outer shape of the conductor changes with a continuous gradient, and the insulating coating is in close contact with an outer periphery of the conductor even in the transition region.

11. The insulated wire has a plurality of the flat portions along an axial direction, The insulated wire according to claim 1 , further comprising the lower flat portion between two of the flat portions.

12. A wire harness comprising the insulated wire according to any one of claims 1 to 11.

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