Insulated Wire and Wire Harnesses

Abstract

To provide an insulation wire which allows easy processing involving removal of insulation coating while having a flat part where the cross section of a conductor is flat-shaped; and to provide a wire harness with such an insulation wire.SOLUTION: An insulation wire 1 has a conductor 11 obtained by twisting a plurality of single wires, and insulation coating 13 coating an outer periphery of the conductor 11. The insulation wire 1 has a flat part 20 and a low flat part 30 along an axial direction x with each of the single wires constituting the conductor 11 and the insulation coating 13 continuing mutually. The outer shape of the conductor 11 on a cross section orthogonal to the axial direction x of the insulation wire 1, 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. An adhesion force between the conductor 11 and the insulation coating 13 is smaller than that of the flat part 20 on the low flat part 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Flat cables made of flat conductors are well known, and the use of flat cables can reduce the space occupied when installed compared to general electric wires with conductors having a substantially circular cross section.

[0003] In conventional general 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 applicant disclose electric wire conductors in which a stranded wire made by twisting together multiple wires 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] Japanese Patent Application Laid-Open No. 2014-130739 [Patent Document 2] Japanese Patent Application Publication No. 2019-149242 [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, flat electric wires having conductors formed by flattening twisted wires are excellent in both space saving and flexibility. However, tools such as wire strippers for removing the insulating coating and terminals for attaching to the terminals that have traditionally been used for general electric wires with a generally circular cross section (round electric wires) cannot be directly applied to such flat electric wires. Furthermore, compared to round electric wires with the same conductor cross-sectional area, flat electric wires tend to have a larger surface area of the conductor, which leads to stronger adhesion between the insulating coating and the conductor. As a result, a large force is required to remove the insulating coating at the terminals of the flat electric wires for attaching terminals, etc. As such, processing that involves removing the insulating coating at the terminals of flat electric wires can be difficult.

[0006] In view of the above, an object of the present invention is to provide an insulated wire that has a flat portion where the cross section of the conductor is flattened, and that can be easily processed by removing the insulating coating, and a wire harness including such an insulated wire. [Means for solving the problem]

[0007] An insulated wire according to a first embodiment of the present disclosure is an insulated wire having a conductor formed by twisting together a plurality of strands of wire and an insulating coating that covers the outer periphery of the conductor, wherein the strands of wire that make up the conductor and the insulating coating are continuous with each other, and the insulated wire 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 wire is flat in the flat portion and has a shape with a smaller flatness in the low flat portion than in the flat portion, and the adhesion between the conductor and the insulating coating is smaller in the low flat portion than in the flat portion.

[0008] The insulated wire according to the second embodiment of the present disclosure is manufactured by compressing a conductor made of multiple strands twisted together 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 region other than the low-flatness portion as a flat portion.

[0009] The insulated wire according to the third embodiment of the present disclosure is manufactured by covering the outer periphery of a conductor made of multiple strands twisted together with an insulating coating to form an insulated wire, and then applying compressive forces to the insulated wire from mutually opposing directions in certain regions along the axial direction of the insulated wire to increase the flatness of the conductor, thereby forming flat portions, and leaving areas other than the flat portions as low-flat portions.

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

[0011] The insulated wire and wire harness according to the present disclosure are an insulated wire that has a flat portion where the cross section of the conductor is flattened, and that can be easily processed by removing the insulating coating, and a wire harness that includes such an insulated wire. [Brief explanation of the drawings]

[0012] [Figure 1] 1A to 1C are schematic diagrams showing an insulated wire according to one 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 element wires constituting the conductor are omitted. [Figure 2] 2A and 2B are cross-sectional views showing a flat portion and a low flat portion, respectively, of the insulated wire according to the embodiment. [Figure 3]Fig. 3 is a schematic diagram showing an insulated wire having a plurality of regions with different flattening directions as a flattened portion. Fig. 3A is a perspective view. Fig. 3B is a cross-sectional view showing a first region corresponding to the CC cross section in Fig. 3A and a third region corresponding to the EE cross section. Fig. 3C is a cross-sectional view showing a second region corresponding to the DD cross section in Fig. 3A. In each figure, the element wires constituting the conductor are omitted. [Figure 4] FIG. 4 is a diagram illustrating a method for manufacturing an insulated wire according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating a method for manufacturing an insulated wire according to another embodiment of the present disclosure. [Figure 6] 6A and 6B are cross-sectional images and tables summarizing the results of various evaluations for the flat and low-flat portions of Sample 1 and Sample 2, respectively.

[0013] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. An insulated wire according to a first embodiment of the present disclosure is an insulated wire having a conductor formed by twisting together a plurality of strands of wire and an insulating coating that covers the outer periphery of the conductor, wherein the strands of wire that make up the conductor and the insulating coating are continuous with each other, and the insulated wire 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 wire is flat in the flat portion and has a shape with a smaller flatness in the low flat portion than in the flat portion, and the adhesion between the conductor and the insulating coating is smaller in the low flat portion than in the flat portion.

[0014] The insulated wire has a continuous flat portion where the conductor has a flattened shape and a low-flat portion where the conductor has a small flatness. Compared to the flat portion, the low-flat portion has a cross-sectional shape closer to that of a conventional round electric wire. Therefore, when performing processing such as removing the insulating coating and attaching external components such as terminals, if the processing is performed on the low-flat portion, it is easy to use tools such as wire strippers and external components such as terminals that are conventionally used for round electric wires. Furthermore, since the adhesion force between the conductor and the insulating coating is smaller in the low-flat portion than in the flat portion, the insulating coating can be removed with less force in the low-flat portion. In this way, by performing processing on the low-flat portion while obtaining the space-saving effect of the flat portion, processing of the insulated wire that involves removing the insulating coating can be easily performed. In the flattened portion, the insulating coating adheres to the conductor with a strong adhesive force. Therefore, even if the adhesive force is weaker in the less flattened portion, the entire insulated wire is prevented from misaligning between the insulating coating and the conductor, and heat dissipation from the conductor via the insulating coating can be ensured when current is applied.

[0015] In this way, an insulated electric wire having both a flat portion and a low flat portion, and in which the adhesion between the conductor and the insulating coating is reduced in the low flat portion, can be easily manufactured by a method in which, in a partial region of a flat electric wire in which an insulating coating is formed around the periphery of a flat-shaped conductor, a force is applied to the conductor so as to compress it from the outside in the width direction of the flat shape, thereby deforming the conductor, thereby reducing the flatness of the conductor and forming a low flat portion. Alternatively, such an insulated electric wire can be easily manufactured by a method in which, in a partial region of a low flatness electric wire in which an insulating coating is formed around the periphery of a conductor with a small flatness, such as a round electric wire, a force is applied to the conductor so as to compress it from opposite directions, thereby deforming the conductor, thereby increasing the flatness of the conductor and forming a flat portion.

[0016] Preferably, the adhesive strength between the conductor and the insulating coating is 20% or more smaller in the low-flatness portion than in the flat portion, which makes it particularly easy to remove the insulating coating in the low-flatness portion.

[0017] The void ratio, which is the proportion of voids not occupied by the wires in the area of the region surrounded by the inner periphery of the insulating coating in the cross section, may be greater in the low-flat portion than in the flat portion. In the low-flat portion, voids formed between the conductor and the insulating coating reduce the adhesive strength between the conductor and the insulating coating. Furthermore, the voids formed between the conductor and the insulating coating and between the wires constituting the conductor increase the flexibility of the low-flat portion. Therefore, by having a void ratio greater in the low-flat portion than in the flat portion, the ease of peeling the insulating coating and flexibility in the low-flat portion can be effectively improved. An insulated electric wire having a void ratio greater in the low-flat portion than in the flat portion can be easily manufactured by applying force to the flat electric wire to form the low-flat portion.

[0018] In this case, it is preferable that the porosity in the cross section is 20% or more higher in the low flat portion than in the flat portion, thereby making it possible to particularly effectively improve the ease of peeling and flexibility in the low flat portion.

[0019] In the cross section of the low-flat portion, the regions outside the conductor along the directions corresponding to the width and height directions of the flat shape may be defined as a width-direction outer-conductor region and a height-direction outer-conductor region, respectively, 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. As described above, the gap formed between the conductor and the insulating coating reduces the adhesive force between the conductor and the insulating coating. When a force is applied to the flat electric wire from the outside in the width direction to form a low-flat portion, the width dimension of the conductor in the low-flat portion becomes smaller, and therefore a gap is more likely to be formed between the conductor and the insulating coating in the width-direction outer-conductor region.

[0020] In the cross section, the difference in the length of the inner circumference of the insulating coating between the flat portion and the low-flat portion may be 5% or less of the length of the inner circumference of the insulating coating in the flat portion. When a force is applied to the flat electric wire to deform it and form the low-flat portion, the change in the length of the inner circumference of the insulating coating is limited by the inner peripheral surface of the insulating coating. Therefore, an insulated electric wire in which the difference in the length of the inner circumference of the insulating coating between the flat portion and the low-flat portion is kept to 5% or less of the length of the inner circumference of the insulating coating in the flat portion can be easily manufactured using a flat electric wire as a raw material.

[0021] The insulated wire may have, as the flat portion, a plurality of regions in which the flat shape has different directions. The flat portion exhibits high flexibility when bending in the height direction of the flat shape. Therefore, if the flat portion of the insulated wire has a plurality of regions in which the flat shape has different directions, each region becomes easier to bend in the height direction of the respective flat shape, and therefore, a single insulated wire can have a plurality of regions that are easier to bend in different directions. For example, when an insulated wire needs to be bent into a complex shape, such as for three-dimensional wiring, by forming a flat portion in each region of the insulated wire so that the height direction of the flat shape faces the desired bending direction, the wire can be easily bent even into a complex shape.

[0022] The insulated wire may have the low-flatness portion on at least one side of the flat portion along the axial direction. An insulated wire having a low-flatness portion on at least one side of the flat wire, such as a terminal portion, can utilize the space-saving properties of the flat portion for wiring, while easily performing processing such as removing the insulating coating and attaching terminals or connectors using the low-flatness portion. By performing these processing operations on the low-flatness portion, which has a cross-sectional shape with a low degree of flatness, there is no need to use terminals or connectors that are flat to match the shape of the flatness portion.

[0023] The insulated wire according to the second embodiment of the present disclosure is manufactured by compressing a conductor made of multiple strands twisted together 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 region other than the low-flatness portion as a flat portion.

[0024] In the insulated wire according to the second embodiment, a flat wire having a flat conductor coated with an insulating coating is subjected to an operation of compressing the conductor by applying a force from the outside in the width direction, thereby reducing the adhesive force between the conductor and the insulating coating in the low-flatness portion. Therefore, in the low-flatness portion, processing involving removal of the insulating coating is facilitated, in addition to the effect of the low flatness itself. This results in an insulated wire that is excellent in both the space-saving effect of the flatness portion and ease of processing in the low-flatness portion. Furthermore, by applying a force from the outside in the width direction to the flat wire to compress the conductor, voids that are not occupied by the wires are likely to be formed in the region inside the insulating coating in the low-flatness portion. Such voids are highly effective in reducing the adhesive force between the conductor and the insulating coating and improving flexibility in the low-flatness portion.

[0025] The insulated wire according to the third embodiment of the present disclosure is manufactured by covering the outer periphery of a conductor made of multiple strands twisted together with an insulating coating to form an insulated wire, and then applying compressive forces to the insulated wire from mutually opposing directions in certain regions along the axial direction of the insulated wire to increase the flatness of the conductor, thereby forming flat portions, and leaving areas other than the flat portions as low-flat portions.

[0026] In the insulated electric wire according to the third embodiment, the adhesive strength between the conductor and the insulating coating is also weaker in the low-flatness portion than in the flat portion by compressing the low-flatness insulated electric wire from opposing directions. Therefore, in the low-flatness portion, processing involving removal of the insulating coating is easier, in addition to the effect of the low flatness itself. This results in an insulated electric wire that is excellent in both space-saving due to the flatness portion and ease of processing in the low-flatness portion. By applying force to an insulated electric wire having a conductor with a low flatness, such as a round electric wire, to deform it and form a flat portion, an insulated electric wire having an integrated low-flatness portion and a flat portion can be easily formed using a general-purpose insulated electric wire as a raw material.

[0027] A wire harness according to the present disclosure includes the insulated wire according to the present disclosure. As described above, the insulated wire according to the present disclosure has a flat portion that exhibits high space-saving properties and flexibility, and a low-flat portion that allows for easy processing involving removal of the insulating coating. Taking advantage of these properties, the wire harness as a whole can be suitably used for applications such as connecting devices in places with limited space, such as inside an automobile.

[0028] [Details of the embodiments of the present disclosure] Insulated wires and wire harnesses according to embodiments of the present disclosure are described in detail below with reference to the drawings. In this specification, concepts such as straight, parallel, and perpendicular, which indicate the shape and arrangement of components in relation to the shape of each part of an insulated wire, include deviations from the geometric concepts within the range allowable for this type of insulated wire, such as deviations of approximately ±15% in length and deviations of approximately ±15° in angle. In this specification, unless otherwise specified, the cross section of an insulated wire or conductor refers to a cross section taken perpendicular to the axial direction (longitudinal direction).

[0029] <Outline of insulated wire> FIG. 1A shows one example of the present disclosure. fruitAn insulated wire 1 according to the embodiment is shown in a perspective view. Also, Figures 1B and 1C show simplified cross-sectional views taken along lines AA and BB in Figure 1A, respectively. Furthermore, Figures 2A and 2B show detailed cross-sections of the flat portion corresponding to Figure 1B and the low flat portion corresponding to Figure 1C, respectively.

[0030] The insulated wire 1 according to this embodiment includes 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 twisted together. The insulating coating 13 covers the entire outer periphery 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. In other words, the strands 12 constituting the conductor 11 are integrally continuous with each other between the flat portion 20 and the low flat portion 30. Furthermore, 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.

[0031] In the flattened portion 20, the conductor 11 has a flattened cross-section. Here, the flattened cross-section of the conductor 11 refers to a state in which the width w, which is the length of the longest line that crosses the cross-section parallel to the sides or diameters constituting the cross-section and encompasses the entire cross-section, is greater than the height h, which is the length of the line that is perpendicular to the longest line and encompasses the entire cross-section. The cross-section of the conductor 11 may have any specific shape as long as it is flat. 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 rectangle with arcs joined to both ends). From the viewpoints of improving space-saving and enhancing continuity with the low-flat portion 30, the aspect ratio w / h of the flattened portion 20 is preferably, for example, between 2 and 6. Hereinafter, in the entire 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.

[0032] In the low flatness portion 30, the conductor 11 has a shape with a smaller flatness in cross section than the flatness portion 20. Here, a small flatness of the conductor 11 means that the aspect ratio w / h of the cross section of the conductor 11 is small, and the cross-sectional shape is less flat. The specific shape of the low flatness portion 30 is not particularly limited, and examples include shapes that can approximate shapes with no or low anisotropy, such as a square, circle, or hexagon, as well as shapes that can approximate shapes with a smaller aspect ratio w / h than the flatness portion 20, such as a rectangle, ellipse, or oval. The smaller the flatness of the low flatness portion 30, the better. A shape with a cross section that can approximate a circle or a square, with an aspect ratio w / h of 1, is particularly preferred. Furthermore, a shape that can approximate a circle in cross section is most preferred. However, if the aspect ratio w / h of the low flatness portion 30 is set to, for example, 2 or less, the effect of improving the processability of the low flatness portion 30, as described below, can be sufficiently obtained. Furthermore, the aspect ratio w / h of the low flat portion 30 may be set to approximately 20% or more and 70% or less of the aspect ratio w / h of the flat portion 20. It is preferable that the dimension w of the low flat portion 30 in the width-equivalent direction is not smaller than the dimension h of 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 preclude the low flat portion 30 from having a vertically elongated cross-sectional shape. In such a case, it is preferable that the aspect ratio h / w of the low flat portion 30 be smaller than the aspect ratio w / h of the flat portion 20. Furthermore, from the viewpoint of improving the processability of the low flat portion 30, the aspect ratio h / w of the low flat portion 30 may be set to 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 be approximately 20% or more and 70% or less of the aspect ratio w / h of the flat portion 20 .

[0033] As described above, the insulated wire 1 having the flat portion 20 and the low-flat portion 30 integrally formed therein can be suitably produced from a raw flat electric wire 9 obtained by deforming the conductor 11 into a flat shape, as shown in FIG. 4 . The raw flat electric wire 9 can be produced by compressing the conductor 11, which has a circular cross section and is made up of a plurality of stranded wires 12, into a flat shape and then covering the outer periphery of the conductor 11 with an insulating coating 13. In this case, as described in Patent Documents 3 to 5, the conductor 11 can be suitably compressed using rollers from both sides in the height direction and optionally from both sides in the width direction. The insulating coating 13 is preferably formed on the outer periphery of the compressed conductor 11 by extrusion molding a resin composition. In a partial region of the raw flat electric wire 9 obtained in this manner along the axial direction, specifically in a region where the low-flat portion 30 is to be formed, a force F1 is applied from the outside of the raw flat electric wire 9 toward the inside along the width direction (y direction) to deform the conductor 11. The application of force F1 reduces the width dimension of the conductor 11, thereby decreasing the flatness of the conductor 11. This operation allows the formation of low flatness portions 30. The application of force F1 can be performed manually or by processing using a tool such as a hammer, or a device such as a molding die or press. The force F1 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 9. Regions of the raw flat electric wire 9 other than the regions where the low flatness portions 30 have been formed by the application of force F1 remain as flatness portions 20.

[0034] After forming the low-flat portions 30 by applying force F1, it is preferable not to heat the insulating coating 13 in a region including the low-flat portions 30 to tightly adhere the insulating coating 13 to the conductor 11. As will be explained later, this is done to maintain a small adhesion force between the conductor 11 and the insulating coating 13 in the low-flat portions 30 and to leave many voids in the region surrounded by the insulating coating 13. However, the insulating coating 13 may be heated in a region including the low-flat portions 30 to deform the insulating coating 13, thereby disposing voids at desired locations between the conductor 11 and the insulating coating 13. For example, when the low-flat portions 30 have a vertically elongated cross-sectional shape (w / h<1), it is possible to deform the insulating coating 13 so that voids are unevenly distributed outside the conductor 11 in the height direction, i.e., in the region outside the vertically elongated direction.

[0035] The insulated wire 1 according to this embodiment has a flat portion 20 having a flat cross-sectional shape, which allows for high space-saving performance and makes it suitable for routing in narrow spaces or in close proximity to other components. Meanwhile, the low-flat portion 30 has a cross-sectional shape with low flatness, similar to that of a conventional round electric wire. This makes it easy to perform processing, such as removing the insulating coating 13, on the low-flat portion 30 using tools and devices that are used for conventional round electric wires, such as wire strippers. Furthermore, external components, such as terminals and connectors, that are attached to the insulated wire 1 can be easily used, without the need for specially shaped components that match the flat shape. In this way, processing the insulated wire 1 using the low-flat portion 30 makes it easy to perform processing, such as removing the insulating coating 13. The insulated wire 1 according to this embodiment can be suitably used in locations where routing space is limited, such as inside an automobile, and where processing involving removal of the insulating coating 13 is required for connection to external components, etc.

[0036] In this embodiment, the positions and number of the low flat portions 30 in the axial direction of the insulated wire 1 are not particularly limited. The low flat portions 30 may be formed at any locations where processing such as removal of the insulating coating 13 is expected. As described above, the low flat portions 30 can be formed on the raw flat electric wire 9 simply by applying a force F1 that deforms the conductor 11 from outside the insulating coating 13. This makes it possible to easily manufacture various insulated electric wires 1 requiring low flat portions 30 in different locations using a common raw flat electric wire 9. A preferred embodiment includes a low flat portion 30 on at least one or both sides of the flat portion 20 along the axial direction of the insulated electric wire 1. Furthermore, a preferred embodiment is one in which the low flat portion 30 is formed on at least one end or both ends of a single insulated electric wire 1, and the remaining region of the insulated electric wire 1, such as a mid-region between the two low flat portions 30, is the flat portion 20. This makes it possible to utilize the space-saving properties of the flat portion 20 when routing the insulated electric wire 1 in intermediate areas, etc., and when it is advantageous to provide a lower flat portion 30 than the flat portion 20 at at least one of the ends of the insulated electric wire 1 from the standpoint of convenience in connecting to external components, by providing a lower flat portion 3 at that end, it becomes possible to easily perform the processing required for connecting to external components such as terminals and connectors, including removal of the insulating coating 13.

[0037] In the insulated electric wire 1 according to this embodiment, the material, wire diameter, and conductor cross-sectional area of the wires 12 constituting the conductor 11 are not particularly limited. However, from the viewpoint of enhancing the space-saving effect of the flattened portion 20 and the effect of improving workability by providing the low-flattened portion 30, it is preferable to use a conductor 11 with 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 often has a large conductor cross-sectional area because its conductivity is lower than that of copper or copper alloy. In addition, the conductor cross-sectional area is preferably 10 mm or less. 2 Above, even 50mm 2 Over 100mm 2 The outer diameter of the wires 12 constituting the conductor 11 is preferably in the range of 0.3 mm or more and 1.0 mm or less, for example.

[0038] The insulated wire 1 according to the present embodiment may be used alone or as a component of a wire harness according to an embodiment of the present disclosure. The wire harness according to the embodiment of the present disclosure includes the insulated wire 1 according to the above embodiment. The wire harness may include a plurality of the insulated wires 1, or may include other types of insulated wires in addition to the insulated wire 1. In a wire harness including a plurality of insulated wires, the plurality of insulated wires are often connected to a common connector at their terminals. In this case, if the insulated wires include wires with flat terminals, the entire connector may become wide to accommodate the flat shape, which may require a large space for connector placement. However, if a wire harness is configured using the insulated wire 1 according to the present embodiment, which has a low-flatness portion 30 formed at its terminal, excessive widening of the connector can be avoided.

[0039] <Comparison of flat and low flat areas> The flat portion 20 and the less flat portion 30 of the insulated wire 1 according to this embodiment differ in structure and characteristics in addition to the difference in the flatness of the cross-sectional shape of the conductor 11.

[0040] (1) Adhesion between the conductor and the insulating coating In the insulated wire 1 according to this embodiment, the adhesion between the conductor 11 and the insulating coating 13 is smaller in the low flatness portion 30 than in the flatness portion 20. The flatness of the flatness portion 20 results in a larger surface area, which makes it in contact with the insulating coating 13 over a larger area. This results in a larger adhesion per unit length along the axial direction between the conductor 11 and the insulating coating 13. However, the low flatness portion 30 has a lower cross-sectional shape, which makes the surface area of the conductor smaller than that of the flatness portion 20 having the same conductor cross-sectional area, resulting in a smaller contact area with the insulating coating 13. Therefore, the adhesion per unit length along the axial direction between the conductor 11 and the insulating coating 13 is smaller in the low flatness portion 30 than in the flatness portion 20.

[0041] Furthermore, when the raw flat electric wire 9 is deformed to form the low flatness portion 30, the adhesive force between the conductor 11 and the insulating coating 13 in the low flatness portion 30 is likely to be further reduced. In the flatness portion 20, the raw flat electric wire 9 maintains the state in which the insulating coating 13 is formed in close contact with the outer periphery of the conductor 11 by extrusion molding or the like, so a relatively large adhesive force is generated between the conductor 11 and the insulating coating 13. However, the low flatness portion 30 is formed by applying force F1 to the conductor 11 from outside the insulating coating 13 to deform the raw flat electric wire 9, so the adhesive force between the insulating coating 13 and the conductor 11 is eliminated or reduced as a result of the application of force F1 and the deformation of the conductor 11. Therefore, the adhesive force between the insulating coating 13 and the conductor 11 in the low flatness portion 30 is likely to be significantly smaller than that in the flatness portion 20.

[0042] In the low flatness portion 30, the adhesive force between the conductor 11 and the insulating coating 13 is reduced, which not only provides the effect of the low flatness shape itself described above, but also improves ease of processing of the low flatness portion 30, which involves removing the insulating coating 13. This is because the insulating coating 13 exerts only a low adhesive force on the conductor 11, so only a small force is required to peel and remove the insulating coating 13 from the outer periphery of the conductor 11 in the low flatness portion 30. From the viewpoint of enhancing the effect of improving the peelability of the insulating coating 13, it is preferable that the adhesive force in the low flatness portion 30 is smaller, and it is, for example, preferably 5% or more, further 10% or more, or 20% or more, or 30% or more smaller than the adhesive force in the flatness portion 20. In other words, assuming that the adhesion force of the flat portion 20 is A1 and the adhesion force of the low flat portion 20 is A2, it is desirable that the adhesion force difference rate ΔA expressed by the following equation (1) be ΔA≦-5%, or even ΔA≦-10%, or ΔA≦-20%, or ΔA≦-30%. ΔA=(A2-A1) / A1 (1) From the viewpoint of improving the peelability of the insulating coating 13, no particular lower limit is set for the adhesion force of the low-flat portion 30, but from the viewpoint of preventing misalignment of the insulating coating 13 relative to the conductor 11, it is preferable to set the adhesion force difference rate within the range of, for example, ΔA≧−90% or ΔA≧−80%.

[0043] The low flatness portion 30 increases the peelability of the insulating coating 13 due to the low adhesion between the conductor 11 and the insulating coating 13, while the flatness portion 20 allows the insulating coating 13 to adhere to the outer periphery of the conductor 11 with a strong adhesive force, thereby suppressing the displacement of the insulating coating 13 relative to the conductor 11. Furthermore, when the conductor 11 generates heat due to the passage of electricity through the insulating coating 13, the heat is dissipated at the point where the insulating coating 13 and the conductor 11 are in close contact without passing through an air layer. Absolute The heat is efficiently transferred to the edge coating 13 and then dissipated into the external environment, ensuring high heat dissipation in the flat portion 20. The effects of suppressing misalignment and improving heat dissipation in the flat portion 20 are exerted as properties of the insulated wire 1 as a whole.

[0044] The adhesion between the conductor 11 and the insulating coating 13 can be evaluated by a pull-out test. Specifically, for example, a section including only the flat portion 20 or only the low-flat portion 30 is cut from the insulated wire 1, and the insulating coating 13 is stripped off over a predetermined length of the end to expose the conductor 11. The exposed conductor 11 is then inserted into a through-hole having the same shape as the outer shape of the conductor 11, and the conductor 11 is pulled at a predetermined speed to remove it from the insulating coating 13. The load required for the pull-out is measured using a load cell or the like, and the maximum load is taken as the adhesion between the insulating coating 13 and the conductor 11. The measured adhesion between the flat portion 20 and the low-flat portion 30 cut to the same length is then compared.

[0045] (2) Distribution of voids In the cross section of the insulated wire 1 according to this embodiment, the distribution of voids in the region surrounded by the insulating coating 13 also differs between the flat portion 20 and the low flat portion 30. In the insulated wire 1 according to this embodiment, the low flat portion 30 tends to have a larger void ratio than the flat portion 20. Here, the void ratio refers to the proportion of the area of voids 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.

[0046] The reason why the void ratio tends to be large in the low flatness portions 30 is related to the method for forming the low flatness portions 30. When a force F1 is applied from the outside of the raw flat electric wire 9 to form the low flatness portions 30, the conductor 11 in the cross section of the insulated electric wire 1 is deformed and the shape of the insulating coating 13 also changes in a direction that decreases the flatness, but the inner perimeter of the insulating coating 13 remains almost unchanged. If the inner perimeter of the insulating coating 13 remains the same, the area of the region surrounded by the inner perimeter of the insulating coating 13 increases as the insulating coating 13 deforms to a shape with a lower flatness. In this case, the area occupied by the wires 12 in the region surrounded by the inner perimeter of the insulating coating 13 remains the same, so the area of the voids not occupied by the wires 12 increases, and the void ratio increases.

[0047] When forming the low-flat portion 30, a force F1 is applied to the conductor 11 from outside the insulating coating 13, so voids are likely to form between the outer periphery of the conductor 11 and the inner periphery of the insulating coating 13. The formation of these voids between the conductor 11 and the insulating coating 13 also contributes to reducing the adhesive force between the conductor 11 and the insulating coating 13. In particular, the force F1 for deforming the conductor 11 is applied from the outer side to the inner side in the width direction, compressing the dimension of the conductor 11 in the width direction. Therefore, as shown in FIG. 2B , voids are likely to be unevenly distributed in the outer region of the conductor 11 in the width equivalent direction. In other words, larger voids are likely to form in the width-direction outer-conductor region Rw, which is the region outside the conductor 11 along the width equivalent direction (y direction), than in the height-direction outer-conductor region Rh, which is the region outside the conductor 11 along the height equivalent direction (z direction). As a result, 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 Rw than in the height-direction outer-conductor region Rh, and the adhesion force between the conductor 11 and the insulating coating 13 is likely to be smaller in the width-equivalent direction than in the height-equivalent direction. Note that gaps may be unevenly distributed toward the width-direction outer-conductor region Rw not only in the low flat portion 30 but also in the boundary between the low flat portion 30 and the flat portion 20.

[0048] The increased void ratio in the low flat portion 30 not only reduces the adhesive force between the conductor 11 and the insulating coating 13 but also increases the bending flexibility of the insulated wire 1 in the low flat portion 30. This is because, when the conductor 11 is bent, the movement of the wires 12 into the voids assists in the flexible bending of the insulated wire 1. While voids formed between the conductor 11 and the insulating coating 13, such as in the widthwise outer-conductor region Rw, are also effective in improving flexibility, voids formed between the wires 12 inside the conductor 11 are particularly effective in improving flexibility. Therefore, from the perspective of increasing the bending flexibility in the low flat portion 30, it is preferable that the void ratio in the low flat portion 30 be greater than that in the flat portion 20 not only in the entire region surrounded by the inner periphery of the insulating coating 13 but also in the region inside the conductor 11.

[0049] The specific void ratio in the low flat portion 30 is not particularly limited. However, it is preferable that the void ratio in the low flat portion 30 is 5% or more, further 10% or more, or even 20% or more, 30% or more, or 45% or more higher than that in the flat portion 20. In other words, assuming that the void ratio in the flat portion 20 is V1 (%) and the void ratio in the low flat portion 30 is V2 (%), it is preferable that the void ratio difference rate ΔV expressed by the following formula (2) is ΔV≧+5%, further ΔV≧+10%, ΔV≧+20%, ΔV≧+30%, or ΔV≧+45%. ΔV=(V2-V1) / V1 (2) Furthermore, it is preferable that the void ratio (V2) in the low flat portion 30 is 30% or more, further 35% or more, or 40% or more. This makes it easier to reduce the adhesive force between the insulating coating 13 and the conductor in the low flat portion 30 and ensure high flexibility. In the flat portion 20, too, from the viewpoint of ensuring bending flexibility in the height direction (z direction), it is preferable that the void ratio (V1) of the flat portion 20 is 10% or more, further 20% or more. 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 preferable that they be approximately 50% or less.

[0050] As explained above, when the low flatness portion 30 is formed by applying force F1 to the raw flat wire 9 and deforming the conductor 11, the length of the inner periphery of the insulating coating 13 remains almost unchanged, but the area of the region surrounded by the inner periphery of the insulating coating 13 increases as the flatness of the region decreases, thereby increasing the porosity of the low flatness portion 30. From the viewpoint of enhancing the effect of increasing the porosity of the low flatness portion 30 through this mechanism, it is preferable that the amount of change in the inner periphery of the insulating coating 13 resulting from the formation of the low flatness portion 30, i.e., the difference in the inner periphery of the insulating coating 13 between the flat portion 20 and the low flatness portion 30, be small. For example, it is preferable that the difference in the inner periphery of the insulating coating 13 between the flat portion 20 and the low flatness portion 30 be 5% or less of the inner periphery of the insulating coating 13 in the flat portion 20. That is, assuming that the inner circumferential length of the insulating coating 13 in the flat portion 20 is D1 and the inner circumferential length of the insulating coating 13 in the low flat portion 30 is D2, the circumferential length difference ratio ΔD expressed by the following formula (3) should be |ΔD|≦5%. It is further preferable that |ΔD|≦2%. ΔD=(D2-D1) / D1 (3)

[0051] Furthermore, from the viewpoint of enhancing the effect of increasing the void ratio in the low flat portion 30 by the above mechanism, it is preferable that the area (internal area) of the region surrounded by the inner periphery of the insulating coating 13 increases significantly as the low flat portion 30 is formed. In other words, it is preferable that the internal area of the low flat portion 30 is larger than that of the flat portion 20. For example, it is preferable that the internal area of the low flat portion 30 is larger than that of the flat portion 20 by 30% or more, or even 50% or more. In other words, where the internal area of the flat portion 20 is S1 and the internal area of the low flat portion 30 is S2, it is preferable that the internal area difference rate ΔS expressed by the following equation (4) be ΔS≧+10%, or even ΔS≧+20%. ΔS=(S2-S1) / S1 (4)

[0052] (3) Deformation of wire When the insulated wire 1 according to this embodiment is manufactured by applying a force F1 to the raw flat wire 9 in the width direction to form the low flatness portions 30, the manufacturing method tends to result in a non-uniform distribution of the deformation rate of the cross-section of the wires 12 in the flatness portions 20 and the low flatness portions 30. Here, the deformation rate of the wires 12 is an index indicating how much the cross-sectional shape of a certain wire 12 deviates from a circular shape, and the more the shape of the wire 12 deviates from a circular shape, the greater the deformation rate.

[0053] 2A and 2B, in both the flat portion 20 and the low flat portion 30, the wires 12 are more likely to have a smaller deformation rate at the widthwise end portions (e.g., region R2) of the outer peripheral portion facing the outer periphery of the conductor 11, which are regions on the outer sides (both ends) along the width equivalent direction (y direction), than at the central portion (e.g., region R1) located inside the outer peripheral portion or the heightwise end portions (e.g., region R3) of the outer peripheral portion along the height equivalent direction (z direction). In other words, in the flat portion 20 and the low flat portion 30, the wires 12 at the widthwise end portions are more likely to have a shape closer to a circle than the wires 12 at the central portion and the heightwise end portions.

[0054] As described above, when the insulated electric wire 1 according to this embodiment is formed from a raw flat electric wire 9 including a flattened stranded conductor, the conductor 11 included in the raw flat electric wire 9 is deformed into a flat shape by applying a gentle force to the stranded wire using a roller. As a result, as described in Patent Documents 3 to 5, the outer periphery, particularly the widthwise ends, has a smaller wire deformation rate than the central portion. When the insulated electric wire 1 according to this embodiment is manufactured from this raw flat electric wire 9, the flat portion 20 retains the structure of the conductor 11 in the raw flat electric wire 9 substantially unchanged. In the low flatness portion 30, the overall outer shape of the conductor 11 is deformed into a shape with a low degree of flatness, but the shape of each strand 12 remains almost unchanged. Therefore, the distribution of the deformation rates of the strands 12 that occurred in the raw flat electric wire 9 is retained almost unchanged in the low flatness portion 30. Therefore, in the flat portions 20 and the less flat portions 30 of the insulated electric wire 1 according to this embodiment, as in the raw flat electric wire 9, the deformation rate of the wires 12 is smaller at the widthwise ends than at the center and heightwise ends.

[0055] <Deformation form: Form that changes the flattening direction of the flat part> The above description has focused on a configuration in which low flatness portions 30 are formed at both ends of an insulated wire 1, and flatness portions 20 of uniform shape are formed between the low flatness portions 30. However, the number and arrangement of the flatness portions 20 and low flatness portions 30 are not limited to this, and any number of flatness portions 20 and low flatness portions 30 may be provided, and any arrangement order may be used. For example, the flatness portions 20 may be provided as multiple regions with different flatness directions. These multiple regions may be provided adjacent to each other, or may be provided with low flatness portions 30 interposed therebetween.

[0056] As an example of providing multiple regions in a flat portion, FIGS. 3A to 3C show an insulated electric wire 1A in which a flat portion 20A is provided with multiple regions with different flattening directions: a first region 21, a second region 22, and a third region 23. These three regions 21 to 23 are provided consecutively in this order along the axial direction of the insulated electric wire 1A. Although not shown, low flattening portions are provided at both ends of the insulated electric wire 1A along the axial direction of the insulated electric wire 1A, corresponding to regions outside the first region 21 and the third region 23 (opposite the second region 22). In the flat portion 20A, the first region 21, the second region 22, and the third region 23 have mutually different flattening directions. Here, the flattening direction refers to the direction of the flat shape of the cross section, i.e., the direction in which the flat shape extends flatly across the width.

[0057] Specifically, the first region 21 and the third region 23 have horizontally elongated flat shapes with their flattening direction oriented in the y direction. On the other hand, the second region 22 has a vertically elongated flat shape with their flattening direction oriented in the z direction. The regions 21 to 23 are directly adjacent to each other, except for regions that inevitably occur due to a sudden change in the flattening direction.

[0058] The flat portion of the insulated electric wire does not exhibit high flexibility in the width direction of the flat shape (i.e., the flattening direction), making it difficult to bend the insulated electric wire, but it exhibits high flexibility in the height direction, making it easy to bend the insulated electric wire. As such, the flat portion has anisotropy in flexibility, and when the flat portion has multiple regions with different flattening directions, the directions in which the insulated electric wire is easily bent differ in these multiple regions. In the example shown in Figures 3A to 3C, the horizontally elongated first region 21 and third region 23 are easily bent in the vertical direction (z direction), while the vertically elongated second region 22 is easily bent in the horizontal direction (y direction).

[0059] In this way, by providing the flat portion 20A with multiple regions 21-23 having different flattening directions, each portion of the flat portion 20A of the insulated wire 1A can be easily bent in a different direction. By bending the insulated wire 1A in different directions in these regions 21-23, the insulated wire 1A can be suitably used for applications that require bending into a complex shape, such as three-dimensional routing or routing around an object with a complex shape. Depending on the specific routing path, etc., a required number of regions may be formed in the insulated wire 1A at the position where the bend is to be formed, with the height direction of the flat shape facing the direction of the bend.

[0060] As described above, the specific flattening direction of each of the regions 21-23 of the flattened portion 20A may be determined appropriately depending on the direction in which the insulated wire 1A is to be bent. The difference in flattening direction between adjacent regions is not particularly limited. For example, if the difference in flattening direction between adjacent regions is 10° or more, the effect of providing multiple regions with different flattening directions can be fully achieved, thereby enabling bending in various directions. However, the greater the difference in flattening direction between adjacent regions, the easier it is to accommodate bending into complex shapes. For example, in the embodiment shown in Figures 3A-3C, the difference in flattening direction between the first region 21 and the second region 22 and between the second region 22 and the third region 23 is both 90°. Thus, it is preferable that the difference in flattening direction between adjacent regions in the flattened portion 20A be 45° or more, particularly 80° or more.

[0061] When the flattened portion 20A has multiple regions 21-23 with different flattening directions, the specific flattening degrees (the aspect ratios of the cross-sectional flattened shapes) of the multiple regions 21-23 and the relationship between the flattening degrees among the multiple regions 21-23 are not particularly limited, as long as each of the multiple regions 21-23 has a higher flattening degree than the low-flattened portion. However, in order to ensure that each of the multiple regions 21-23 exhibits the same degree of flexibility in the height direction of its respective flattened shape and to enable the insulated electric wire 1A to bend with the same degree of flexibility in all directions, it is preferable that the multiple regions 21-23 with different flattening directions exhibit the same degree of flattening. For example, in the flattened portion 20A, it is preferable that the aspect ratios of the cross-sectional shapes of adjacent regions are 80% or more and 120% or less, based on the aspect ratio of the cross-sectional shape of one region. In the illustrated embodiment, the three regions 21-23 have the same flattening degrees.

[0062] In this way, the insulated electric wire 1A having the flat portion 20A including the plurality of regions 21-23 with different flattening directions can be suitably manufactured, similarly to the insulated electric wire 1 described in detail above, by selectively applying force to necessary regions of the raw flat electric wire 9 obtained by deforming the conductor 11 into a flat shape, thereby partially deforming the raw flat electric wire 9. In this case, one of the plurality of flattening regions with different flattening directions, or multiple regions with the same flattening direction, can be formed by leaving the raw flat electric wire 9 without deforming it from its original flat shape. Meanwhile, by applying force from the outside to the inside of the raw flat electric wire 9 along the width direction (y direction), low flat portions and regions of the flat portion 20A with a flattening direction different from that of the original raw flat electric wire 9 can be formed at necessary locations. At this time, a larger force is applied to the portions where flat regions having a different flattening direction from the original raw flat electric wire 9 will be formed than to the portions where low flattening portions will be formed, and the raw flat electric wire 9 is significantly deformed from its original state to a state where the flattening direction changes. When producing the insulated electric wire 1A shown in FIGS. 3A to 3C , for example, the flattening direction of the raw flat electric wire 9 is oriented in the y direction, and a force is applied from the outside to the inside along the width direction (y direction) at a midpoint in the axial direction of the raw flat electric wire 9, thereby deforming the cross-sectional shape from horizontally elongated to vertically elongated, thereby forming the second region 22. Meanwhile, the horizontally elongated flat shape of the raw flat electric wire 9 is left unchanged at both axial sides of the second region 22, thereby forming the first region 21 and the third region 23.

[0063] <Another embodiment> In the insulated wire 1 according to the embodiment described above, processing is performed on a raw flat wire 9 having a flat conductor 11 to form low flatness portions 30 in some regions and leave the other regions as flatness portions 20, thereby allowing the flatness portions 20 and low flatness portions 30 to coexist. However, an insulated wire in which flatness portions and low flatness portions coexist can also be manufactured by a different method. Below, an insulated wire 1′ formed by a different method will be briefly described. Below, a description of the same configuration as in the embodiment described above will be omitted, and the description will focus on the differences from the above.

[0064] As shown in Fig. 5, the insulated wire 1' according to this another embodiment can be manufactured using a raw low-flatness electric wire 9'. Here, the raw low-flatness electric wire 9' is obtained by covering the outer periphery of a conductor 11, which is made by twisting together a plurality of wires 12, with an insulating coating 13 to form the insulated wire 1', and the cross section of the conductor 11 has an outer shape with low flatness, such as a substantially circular shape. For example, a general-purpose round electric wire can be used as the raw low-flatness electric wire 9'.

[0065] A compressive force F2 is applied to a portion of the raw low-flat electric wire 9' from opposing directions to increase the flatness of the conductor 11, thereby forming a flat portion 20'. The area other than the flat portion 20' is left as a low-flat portion 30'. This makes it possible to manufacture an insulated electric wire 1' having a flat portion 20' and a low-flat portion 30'. That is, in the insulated electric wire 1 according to the embodiment described above, the raw low-flat electric wire 9 is processed to form the low-flat portion 30, and the remaining area is made into the flat portion 20, whereas in the insulated electric wire 1' according to this other embodiment, the raw low-flat electric wire 9' is processed to form the flat portion 20', and the remaining area is made into the low-flat portion 30'.

[0066] In the insulated wire 1′ according to this embodiment, as in the insulated wire 1 described above, the insulating coating 13 contacts the conductor 11 over a larger area in the flat portions 20′ than in the low flat portions 30′, and therefore the adhesive strength between the conductor 11 and the insulating coating 13 is smaller in the low flat portions 30′ than in the flat portions 20′. Therefore, by providing the low flat portions 30′ at the terminals of the insulated wire 1′, the low adhesive strength between the conductor 11 and the insulating coating 13, combined with the effect of the low flatness of the outer shape, makes it possible to easily process the insulated wire 1′ in the low flat portions 30′, which involves removing the insulating coating 13. In this embodiment, the adhesive strength in the low flat portions 30′ can be reduced by, for example, 20% or more, or even 30% or more compared to the adhesive strength in the flat portions 20′ (ΔA≦−20%, or even ΔA≦−30%).

[0067] However, in the insulated wire 1′ according to this other embodiment, as will be shown in the examples below, unlike the insulated wire 1 described above, it is difficult to form a state in which the low-flatness portions 30′ have a larger void ratio than the flatness portions 20′. Furthermore, when compressing the raw low-flatness electric wire 9′ into a flat shape, the inner periphery of the insulating coating 13 may be stretched as the flatness increases. Stretching the inner periphery of the insulating coating 13 strengthens the adhesion between the conductor 11 and the insulating coating 13 at the outer widthwise locations, resulting in a greater adhesion in the flatness portions 20′ than in the low-flatness portions 30′. To prevent excessive load from being applied to the insulating coating 13 when the inner periphery of the insulating coating 13 is stretched, it is preferable to use a material with a relatively low tensile modulus and easy elongation for the insulating coating 13. Furthermore, in this type of insulated wire 1', no force that deforms the conductor 11 is applied to the low flatness portion 30' either during the production of the raw low flatness electric wire 9' or during processing of the raw low flatness electric wire 9'. Therefore, in the cross section of the low flatness portion 30', the wires 12 maintain a shape that is close to a circle in cross section with a small deformation rate regardless of the position.

[0068] A method similar to that for the insulated wire 1' described herein can also be used to manufacture an insulated wire 1A having a plurality of regions 21-23 with different flattening directions as the flat portion 20A, as shown in Figures 3A to 3C. In this case, when applying force to the raw low-flat electric wire 9' to form the flat portion 20A, the plurality of regions 21-23 with different flattening directions can be formed by applying the force in different directions to the plurality of regions. When manufacturing the insulated wire 1A having the shape shown in Figures 3A to 3C, a compressive force is applied to the raw low-flat electric wire 9' along the z direction at positions where the horizontally elongated first region 21 and third region 23 are to be formed, and a compressive force is applied to the raw low-flat electric wire 9' along the y direction at positions where the vertically elongated second region 22 is to be formed. [Example]

[0069] Examples are shown below. However, the present invention is not limited to these examples. Here, the state of the flat portion and the low flat portion of two types of insulated wires were compared.

[0070] (Sample preparation) (1) Sample 1 First, a raw flat electric wire was prepared. First, a stranded wire with a roughly circular cross section was prepared by twisting together aluminum alloy wires, and the twisted wire was compressed into a flat shape using a roller to prepare a conductor. The twisted 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 around the outer periphery of the manufactured conductor by extrusion molding to obtain a raw flat electric wire. Cross-linked polyethylene was used as the constituent material of the insulating coating, and the thickness of the insulating coating was 2 mm.

[0071] A low-flatness portion was formed by applying a force from the outside to the inside in the width direction of the flat shape to a certain region of the raw flat electric wire, thereby reducing the flatness of the flat shape of the conductor. The region to which no force was applied was left as a flat portion. The aspect ratio w / h of the conductor in the low-flatness portion was set to approximately 1. The low-flatness portion was formed by pressing at room temperature.

[0072] (2) Sample 2 First, a raw low-profile electric wire was prepared. First, a stranded wire with a substantially circular cross section was prepared by twisting together aluminum alloy wires. The stranded wire had a conductor cross section of 60 mm 2 The wire diameter was 0.32 mm. An insulating coating was formed around the outer periphery of the conductor by extrusion molding to obtain a raw low-profile electric wire. The insulating coating was made of polyvinyl chloride and had a thickness of 2 mm.

[0073] In some areas of the above-mentioned low-raw-material flat wire, a clamping force was applied from opposite directions to compress the conductor and increase the flatness, thereby forming a flattened section. The area to which no force was applied was left as a low-flat section. The aspect ratio w / h of the conductor in the flattened section was approximately 3. The flattened section was formed by pressing at room temperature.

[0074] (Evaluation method) Cross-sectional observations were performed on the flat and low-flat portions of Samples 1 and 2 prepared above. Each sample was embedded and fixed in acrylic resin. The insulated wire was then cut perpendicular to the axial direction at each of the flat and low-flat portions to obtain cross-sectional samples. The obtained cross-sectional samples were observed under a microscope, and image analysis was performed on the observed images to evaluate the gap area, internal area, porosity, and internal circumference of the region inside the insulating coating. For the low-flat portion of Sample 1 and the flat portion of Sample 2, cross-sectional samples were prepared at three locations, positions 1 to 3, and evaluations were performed. The obtained values were then averaged for the three locations.

[0075] Separately, the adhesion strength between the conductor and the insulating coating was evaluated for the insulated wires of Samples 1 and 2 at both the flat and low-flat portions. A 70 mm section was cut out from each sample, including either the flat or low-flat portion, and the insulating coating was removed from a 25 mm area from the end to expose the conductor. A through-hole with the same shape as the conductor's outer shape was formed in a metal plate, and the exposed conductor was inserted through the through-hole. The conductor was then pulled at a speed of 250 mm / s to remove it from the insulating coating. The load required for removal was measured using a load cell, and the maximum load was taken as the adhesion strength of the insulating coating to the conductor.

[0076] (Evaluation results) Figures 6A and 6B show cross-sectional images at each position for Sample 1 and Sample 2, as well as the results of the evaluation of the cross-sectional state and the results of the adhesion measurement. Note that the scale of the cross-sectional images has been changed appropriately for the flat and low-flat areas. The table also shows the difference rate between the flat and low-flat areas for each measurement value. Here, the difference rate indicates the percentage change in the value of the low-flat area, with the value of the flat area being used as the reference. In other words, the difference rate is expressed by the following equation (5). Difference rate = (value of low flat area - value of flat area) / value of flat area × 100% (5) When cross-sections were evaluated at multiple positions, the average value was used to calculate the difference rate. In Figures 6A and 6B, the values used to calculate the difference rate and the calculated difference rate are displayed in bold.

[0077] The cross-sectional image of Sample 1 shown in Figure 6A confirms that the low-flatness portion, formed by applying force to the raw flat wire, has a shape with a lower degree of flatness than the flat portion. Furthermore, when comparing the measurement results of the adhesion strength between the flat and low-flatness portions, the low-flatness portion has a smaller value, and the difference rate is ΔA≦-30%. In other words, the reduction in flatness reduces the adhesion strength between the insulation coating and the conductor by 30% or more.

[0078] Focusing on the distribution of voids not occupied by the wires in the cross-sectional image, we can see that in the flat section, the insulation coating adheres tightly to the outer periphery of the conductor, and the voids between the conductor and the insulation coating are very small, whereas in the low-flat section, there are obvious voids between the conductor and the insulation coating. Furthermore, the voids are unevenly distributed in the width direction (horizontal direction of the image). The uneven distribution of voids is particularly noticeable at positions 2 and 3. Furthermore, it can be seen that the voids in the region between the wires inside the conductor are larger in the low-flat section than in the flat section. From these findings, it can be seen that the voids formed in the region surrounded by the inner periphery of the insulation coating are larger in the low-flat section than in the flat section. These results are further demonstrated by the fact that the measured void area and void ratio are larger in the low-flat section than in the flat section, and that the difference between them is a positive value. The porosity is 50% or more higher in the low-flat area (ΔV≧+50%) than the value in the flat area.

[0079] The inner perimeter of the insulation coating does not change between the flat and low-flat sections (ΔD = 0%). On the other hand, the inner area of the insulation coating in the low-flat section is 20% larger than the value in the flat section (ΔS ≧ +20%).

[0080] From the above results, it can be interpreted that when a low-flat portion is formed by applying force from the outside in the width direction to the raw flat electric wire, the conductor deforms into a low-flat shape within the space where the change in the inner periphery length of the insulating coating is limited, thereby increasing the area of the space surrounded by the inner periphery of the insulating coating and thereby increasing the void ratio. Furthermore, it is thought that the increase in void ratio, particularly the formation of voids in the region between the conductor and the insulating coating, reduces the adhesion between the insulating coating and the conductor.

[0081] Next, the cross-sectional image of Sample 2 shown in Figure 6B confirms that the low-flatness portion, which retains the structure of the raw low-flatness electric wire, has a shape with a lower degree of flatness than the flatness portion formed by applying a compressive force to the raw low-flatness electric wire. Furthermore, when comparing the measurement results of the adhesion strength between the flatness portion and the low-flatness portion, the low-flatness portion has a smaller value, and the difference rate is also ΔA≦-30%. In other words, compression of the raw low-flatness electric wire increases the adhesion strength between the insulation coating and the conductor, and the low-flatness portion remains in a state where the adhesion strength is 30% or more lower than the flatness portion formed after compression.

[0082] Focusing on the distribution of voids in the cross-sectional image, we see that there are almost no voids between the conductor and the insulating coating in both the flat and low-flat sections. It can be seen that the voids between the wires inside the conductor are larger in the flat section than in the low-flat section. In other words, it can be seen that the voids formed in the area surrounded by the inner circumference of the insulating coating are larger in the flat section than in the low-flat section. These results are further demonstrated by the fact that the measured void area and void ratio are larger in the flat section than in the low-flat section, and the difference ratio is also a negative value. This result indicates that compression from a low-flat shape to a flat shape increases the voids inside the conductor.

[0083] In Sample 1, the inner perimeter of the insulating coating did not change after the low-flatness portion was formed by the application of force, whereas in Sample 2, the inner perimeter of the insulating coating in the flat portion was longer than that in the low-flatness portion (difference rate ΔD≦0), and the inner perimeter of the insulating coating expanded after the flatness portion was formed by the application of force. This phenomenon is thought to be due to the insulating coating being stretched as the conductor deforms when the conductor is compressed by the application of force.

[0084] 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 within the scope of the gist of the present invention. [Explanation of symbols]

[0085] 1,1',1A insulated wire 11 Conductor 12 wire 13 Insulation coating 20,20',20A flat part 21 The First Region 22 The Second Realm 23 The Third Realm 30,30' low flat part 9 Raw material flat wire 9' Raw material low flat wire h conductor height w conductor width x Axial direction of insulated wire y width equivalent direction z Height equivalent direction F1 force F2 force R1 Central region R2 Width direction edge area R3 Height direction end area Rh Height direction outside conductor area Rw Outside conductor area in width direction

Claims

1. a conductor in which a plurality of strands are twisted together; an insulating coating covering the 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 the axial direction, an outer shape of the conductor in a cross section perpendicular to the axial direction of the insulated wire is flat at the flat portion and is flatter at the less flat portion than the flat portion; An insulated wire, wherein the adhesive strength between the conductor and the insulating coating is 20% or more smaller in the low flatness portion than in the flatness portion.

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

3. The insulated wire according to claim 2 , wherein the porosity in the cross section is 20% or more higher in the low flatness portion than in the flatness portion.

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

5. 5. The insulated wire according to claim 1, wherein, in the cross section, a difference in length of an inner circumference of the insulating coating between the flat portion and the less flat portion is 5% or less of a length of the inner circumference of the insulating coating in the flat portion.

6. The insulated wire according to claim 1 , wherein the flat portion has a plurality of regions in which the flat shape is oriented in different directions.

7. The insulated wire according to claim 1 , wherein the insulated wire has the low flat portion on at least one side of the flat portion along the axial direction.

8. The conductor, which is made up of multiple strands twisted together, is compressed into a flat shape, and the outer periphery is covered with an insulating coating to form an insulated wire. A force is applied from the outer side to the inner side in the width direction of the flattened shape in a partial region along the axial direction of the insulated wire to reduce the flatness of the conductor, thereby forming a low-flat portion; The insulated wire is manufactured such that the area other than the low-flatness area remains as a flat area.

9. A wire harness comprising the insulated wire according to any one of claims 1 to 8.

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