Electric wire conductor, insulated electric wire, and wire harness

Abstract

Provided are: an electric wire conductor which is obtained by forming a twisted wire formed by twisting a plurality of wires into a flat shape, and which can ensure high flexibility; and an insulated electric wire and a wire harness including said electric wire conductor.　An electric wire conductor 1 is configured as a twisted wire including a plurality of child twisted wires 2 formed by twisting a plurality of wires 3, wherein: a cross-section intersecting with an axial direction of the twisted wire 2 has a flat portion having a flat shape in which a width-direction dimension w is larger than a height-direction dimension h; and in the flat portion, when the total number of the wires 3 constituting outer-layer child twisted wires 2o, disposed at an outer periphery of the flat portion, among the child twisted wires 2, is defined as an outer-layer wire number, and the total number of the wires 3 constituting inner-layer child twisted wires 2i, disposed inside the outer-layer child twisted wires 2o, is defined as an inner-layer wire number, the ratio of the outer-layer wire number to the inner-layer wire number is 2.0 or more.

Description

Technical Field

[0001] The present disclosure relates to electric wire conductors, insulated electric wires, and wire harnesses.

Background Art

[0002] A flat cable configured using a flat-shaped electric wire conductor is known. By using a flat cable, the space occupied during wiring can be reduced compared to the case of using a general electric wire having a substantially circular cross-section electric wire conductor.

[0003] In a conventional general flat cable, as disclosed in Patent Documents 1, 2, etc., a flat conductor is often used as the electric wire conductor. A flat conductor is formed by shaping a single metal wire into a square cross-section. Further, Patent Documents 3 and 4 based on the applicants' applications disclose an electric wire conductor in which a stranded wire obtained by twisting a plurality of 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

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0005] As disclosed in Patent Documents 3 and 4, by using an electric wire conductor in which a stranded wire is formed into a flat shape, it is possible to save space while maintaining flexibility. However, when a force is applied to the stranded wire to form it into a flat shape, a load is applied to the individual strands that make up the stranded wire. Due to the application of the load, the individual strands are deformed. As also described in Patent Documents 3 and 4, for the individual strands on the outer peripheral portion of the electric wire conductor, the deformation can be suppressed to a small extent, but for the inner individual strands, they are more likely to undergo a larger deformation than the individual strands on the outer peripheral portion. When the deformation of the individual strands becomes large, crowding and adhesion of the individual strands occur, and hardening of the material constituting the individual strands occurs, which may cause a decrease in the flexibility of the electric wire conductor. In particular, when the electric wire conductor is formed into a horizontally long, high-flat shape for the purpose of reducing the height occupied by the electric wire conductor and enhancing space-saving properties, a decrease in flexibility due to the deformation of the inner individual strands is likely to occur.

[0006] Therefore, an object is to provide an electric wire conductor in which a stranded wire formed by twisting individual strands is formed into a flat shape and which can ensure high flexibility, as well as an insulated electric wire and a wire harness having such an electric wire conductor.

Means for Solving the Problems

[0007] The electric wire conductor of the present disclosure is configured as a stranded wire including a plurality of sub-stranded wires formed by twisting a plurality of individual strands, and has a flat portion in a cross section intersecting the axial direction of the stranded wire, where the dimension in the width direction is larger than the dimension in the height direction, and in the flat portion, among the sub-stranded wires, the total number of the individual strands constituting the outer-layer sub-stranded wires arranged on the outer periphery of the flat portion is defined as the number of outer-layer individual strands, and the total number of the individual strands constituting the inner-layer sub-stranded wires arranged more inward than the outer-layer sub-stranded wires is defined as the number of inner-layer individual strands, and the ratio of the number of outer-layer individual strands to the number of inner-layer individual strands is 2.0 or more.

[0008] The insulated electric wire of the present disclosure has the electric wire conductor and an insulating coating that covers the outer periphery of the electric wire conductor. The wire harness of the present disclosure includes the insulated electric wire.

Advantages of the Invention

[0009] The wire conductor of the present disclosure is a wire conductor in which a stranded wire obtained by twisting individual strands is formed into a flat shape, and high flexibility can be ensured. Further, the insulated wire and the wire harness of the present disclosure include such a wire conductor.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] [Description of Embodiments of the Present Disclosure] First, the embodiments of the present disclosure will be listed and described. The wire conductor according to the present disclosure is configured as a stranded wire including a plurality of sub-stranded wires formed by twisting a plurality of individual wires, and has a flat portion in a cross-section intersecting the axial direction of the stranded wire, where the dimension in the width direction is larger than the dimension in the height direction. In the flat portion, the total number of the individual wires constituting the outer layer sub-stranded wires arranged on the outer periphery of the flat portion among the sub-stranded wires is defined as the number of outer layer individual wires, and the total number of the individual wires constituting the inner layer sub-stranded wires arranged inside the outer layer sub-stranded wires is defined as the number of inner layer individual wires. The ratio of the number of outer layer individual wires to the number of inner layer individual wires is 2.0 or more.

[0012] In the flat portion of the wire conductor, the ratio of the number of outer layer individual wires to the number of inner layer individual wires is 2.0 or more. That is, the number of individual wires constituting the inner part is 1 / 2 or less compared to the number of individual wires constituting the outer peripheral part of the wire conductor. By reducing the number of individual wires arranged inside the wire conductor, when the wire conductor is deformed into a flat shape by applying a force to form the flat portion, deformation due to the application of a large load is less likely to occur in the individual wires located inside the wire conductor. Then, compared with the case where the number of individual wires arranged inside the wire conductor is large, the denseness and adhesion of the individual wires are alleviated in the inner part of the wire conductor, and when the wire conductor is bent, the inner individual wires are more likely to move. Also, hardening of the constituent material due to deformation of the individual wires is less likely to occur. As a result, the wire conductor has high flexibility.

[0013] Here, it is preferable that the number of individual wires constituting each of the plurality of sub-stranded wires is the same, and the ratio of the number of outer layer sub-stranded wires to the number of inner layer sub-stranded wires is 2.0 or more. Then, by using the same sub-stranded wires throughout the wire conductor and setting the number of sub-stranded wires arranged in the outer peripheral part and the inner part of the wire conductor, as described above, a wire conductor with a small number of individual wires constituting the inner part and having high flexibility in the flat portion can be obtained.

[0014] Also, it is preferable that the ratio of the number of outer layer individual wires to the number of inner layer individual wires is 3.0 or more. Then, it becomes easier to particularly enhance the flexibility of the wire conductor.

[0015] The inner-layer sub-twisted wire may be provided in only one layer on the inner circumference of the outer-layer sub-twisted wire. Then, compared with the case where the inner-layer sub-twisted wires are arranged in two or more layers, it is possible to effectively achieve an improvement in the flexibility of the wire conductor by reducing the number of strands constituting the inner part.

[0016] In the cross-section of the wire conductor, the dimension in the width direction may be 5 times or more the dimension in the height direction. Then, the height occupied by the wire conductor can be reduced, and space-saving performance can be enhanced. The more the wire conductor is formed into a high-flat shape, the greater the load applied to the strands constituting the inner part, and the easier the flexibility of the wire conductor is to decrease. However, as described above, if the ratio of the number of outer-layer strands to the number of inner-layer strands is 2.0 or more, even when such a high-flat shape is adopted, high flexibility can be ensured.

[0017] The insulated wire according to the present disclosure has the wire conductor and an insulating coating that coats the outer circumference of the wire conductor. Further, the wire harness according to the present disclosure includes the insulated wire. These insulated wire and wire harness include the above-described wire conductor that has high flexibility by suppressing the number of strands arranged inside the wire conductor to be small. Therefore, the high flexibility can also be utilized for the entire insulated wire and wire harness.

[0018] [Details of Embodiments of the Present Disclosure] Hereinafter, the wire conductor, insulated wire, and wire harness according to the embodiments of the present disclosure will be described in detail with reference to the drawings. In this specification, regarding the shape of each part of the wire conductor, concepts indicating the shape and arrangement of members such as straight line, parallel, and perpendicular include errors from geometric concepts within a range allowed in this type of wire conductor, insulated wire, and wire harness, such as a deviation of approximately ±15% in terms of length and approximately ±15° in terms of angle. In this specification, the cross-section of the wire conductor refers to a cross-section cut perpendicular to the axial direction (longitudinal direction) unless otherwise specified. Also, various characteristics are values evaluated at room temperature in the atmosphere.

[0019] <Schematic of wire conductors, insulated wires, and wire harnesses> FIG. 1 schematically shows a cross-sectional view of a wire conductor 1 according to an embodiment of the present disclosure. The wire conductor 1 is configured as a stranded wire in which a plurality of strands 3 are twisted together.

[0020] The wire conductor 1 has a flat outer shape at least in part along the axial direction. That is, it has a flat portion where the cross-section perpendicular to the axial direction of the wire conductor 1 is flat. In the present embodiment, the entire axial direction of the wire conductor 1 is treated as such a flat portion. Here, that the cross-section of the wire conductor 1 has a flat shape means that among the straight lines that cross the cross-section parallel to the sides or diameters constituting the cross-section and include the entire cross-section, the width w, which is the dimension of the longest straight line, is larger than the height h, which is the dimension of the straight line orthogonal to that straight line and including the entire cross-section.

[0021] As long as the cross-section of the wire conductor 1 has a flat shape, it may have any specific shape. Examples of the flat shape include a rectangle, an ellipse, an oblong, a oval shape (a shape having semi-circles at both ends of a rectangle), a parallelogram, a trapezoid, etc. If the circumscribed figure of the cross-section can approximate each of these shapes, the cross-sectional shape of the wire conductor 1 can be regarded as taking each shape. Among the listed shapes, it is preferable to adopt any one of a rectangle, an ellipse, an oblong, and an oval shape. In the form shown in FIG. 1, the wire conductor 1 has a cross-sectional shape that can approximate an oval shape.

[0022] In the electric wire conductor 1, not all the strands 3 are twisted together in a lump, but are divided into a plurality of sub-twisted strands 2. That is, a plurality of strands 3 are twisted to form a sub-twisted strand 2, and the electric wire conductor 1 is formed as a conductor wire including a plurality of the sub-twisted strands 2. In the main view of FIG. 1, the cross-section of each sub-twisted strand 2 is simplified and shown as a circle or an ellipse of a solid line (outer-layer sub-twisted strand 2o) and a broken line (inner-layer sub-twisted strand 2i), and the structure of the sub-twisted strand 2 including a plurality of strands 3 is illustrated in the cross-sectional view surrounded by a rectangle. In the electric wire conductor 1, the plurality of sub-twisted strands 2 may simply be gathered in a bundle, but preferably have a parent-twisted structure in which the plurality of sub-twisted strands 2 are twisted together with each other. Each sub-twisted strand 2 may have a cross-section approximating a circle or a cross-sectional shape deformed from a circle. In FIG. 1, the inner-layer sub-twisted strand 2i of the inner part of the cross-section is shown in a flattened deformed form.

[0023] As will be described in detail later, the electric wire conductor 1 can be formed by rolling a raw material twisted wire in which a plurality of sub-twisted strands 2 are twisted into a substantially circular cross-section. Along with the forming into a flat shape, at least a part of the sub-twisted strands 2 and each strand 3 constituting the electric wire conductor 1 may have a cross-sectional shape deformed from a circle. The deformation rate of the sub-twisted strands 2 and the strands 3 from a circle is often smaller at the outer peripheral part of the cross-section of the electric wire conductor 1, particularly at both sides in the width direction, than at the inner part. Also in the electric wire conductors of the embodiments shown in FIGS. 4A to 4D, the deformation rate of the strands at both sides in the width direction is small.

[0024] The electric wire provided with the electric wire conductor 1 according to this embodiment can reduce the space required for routing compared to an electric wire having a substantially circular cross-section electric wire conductor with the same conductor cross-sectional area because the cross-section of the electric wire conductor 1 has a flat shape. That is, it is possible to reduce the space where other electric wires or other members cannot be arranged around a certain electric wire. In particular, the space occupied by the electric wire along the height direction can be reduced, and it is easy to achieve space saving. Further, since the electric wire conductor 1 is composed of a stranded wire in which a plurality of strands 3 are twisted together, it has higher flexibility than a single-wire flat conductor having the same conductor cross-sectional area. The electric wire conductor 1 exhibits high flexibility particularly in the height direction. Thus, since the electric wire conductor 1 has a flat shape, it achieves both high space-saving property and flexibility. The insulated electric wire and wire harness including the electric wire conductor 1 can be particularly preferably used for applications that need to be routed in a narrow space or a complex path, such as inside an automobile, because they have both high space-saving property and flexibility.

[0025] From the viewpoint of particularly enhancing the space-saving property in the height direction, in the cross-section of the electric wire conductor 1, it is preferable that the width is 3 times or more the height. That is, the aspect ratio w / h is preferably 3 or more. The aspect ratio is more preferably 5 or more. Although there is no particular upper limit provided for the aspect ratio of the electric wire conductor 1, from the viewpoint of avoiding applying an excessive load to the electric wire conductor 1 as it is formed into a flat shape, it is advisable to keep it suppressed to about 8 or less.

[0026] The material constituting the wire conductor 1 is not particularly limited, and various metal materials can be applied. Representative metal materials constituting the wire conductor 1 include copper and copper alloys, as well as aluminum and aluminum alloys. In particular, since aluminum and aluminum alloys have a lower conductivity than copper and copper alloys, in order to ensure the required electrical conductivity, the conductor cross-sectional area tends to be large. Therefore, flattening the wire conductor 1 greatly enhances the effect of improving space savings. Also, the larger the conductor cross-sectional area, as will be described later, the greater the effect of ensuring flexibility by reducing the number of individual wires 3 included in the inner layer. From these viewpoints, it is preferable that the wire conductor 1 is made of aluminum or an aluminum alloy.

[0027] Also, from the same viewpoint, it is preferable that the conductor cross-sectional area is 16 mm 2 or more. Since the wire conductor 1 is configured as an aggregate of a plurality of sub-twisted wires 2 instead of twisting a plurality of individual wires 3 together, even if the conductor cross-sectional area is large in this way, the twisting of the individual wires 3 and the forming into a flat shape can be efficiently performed. Although there is no particular upper limit provided for the conductor cross-sectional area, from viewpoints such as facilitating the ensuring of bending flexibility, it is advisable to keep it, for example, at 300 mm 2 or less. Also, the outer diameter of the individual wire 3 constituting the wire conductor 1 is not particularly limited, but a range of 0.12 mm or more and 0.5 mm or less can be exemplified. It is preferable that each individual wire 3 constituting the wire conductor 1 is the same, that is, made of the same material and has the same outer diameter.

[0028] An insulated electric wire according to an embodiment of the present disclosure has an electric wire conductor 1 and an insulating coating (not shown). The insulating coating covers the outer periphery of the electric wire conductor 1 over the entire circumference. The material constituting the insulating coating is not particularly limited as long as it is an insulating material, but it is preferably based on an organic polymer. Examples of the organic polymer include olefin-based polymers such as polyolefins and olefin copolymers, halogen-based polymers such as polyvinyl chloride, various elastomers, and rubbers. The organic polymer may be crosslinked or foamed. Further, the insulating coating may contain various additives such as a flame retardant in addition to the organic polymer. The insulating coating is preferably formed as an extrusion molded body.

[0029] The insulated electric wire according to the embodiment of the present disclosure may be used alone or as a component 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 according to the embodiment of the present disclosure. The wire harness may include a plurality of insulated electric wires according to the embodiment of the present disclosure, or may include other types of insulated electric wires in addition to the insulated electric wire according to the embodiment of the present disclosure. Preferably, a plurality of insulated electric wires according to the embodiment of the present disclosure are arranged in the width direction and / or the height direction. At this time, the specific arrangement structure of the plurality of insulated electric wires is not particularly limited, but as a preferred form, an example is a form in which a plurality of insulated electric wires are arranged in the width direction and fixed to a common sheet material by fusion or the like. In this case, it is particularly preferable that the heights of the plurality of arranged insulated electric wires are aligned.

[0030] <Details of the configuration of the electric wire conductor> As described above, the wire conductor 1 according to the embodiment of the present disclosure includes a plurality of sub-twisted wires 2 formed by twisting a plurality of individual wires 3. In the wire conductor 1, the plurality of sub-twisted wires 2 are arranged in layers. Here, the statement that the plurality of sub-twisted wires 2 are arranged in layers means that a plurality of layers are formed along the direction connecting the outer peripheral portion and the central portion of the wire conductor 1, and the plurality of sub-twisted wires 2 are arranged in a substantially annular shape (the same applies hereinafter when defining the number of layers of the arrangement of the sub-twisted wires 2). Note that for the inner layer, the substantially annular arrangement includes both a single wire arrangement and a linear arrangement in the width direction.

[0031] Specifically, in the wire conductor 1, the sub-twisted wire 2 arranged on the outer periphery of the flat cross-section constitutes the outer layer sub-twisted wire 2o and forms the outer layer. And the sub-twisted wire 2 arranged inside the cross-section rather than the outer layer sub-twisted wire 2o constitutes the inner layer sub-twisted wire 2i and forms the inner layer. All the sub-twisted wires 2 existing inside the outer layer sub-twisted wire 2o become the inner layer sub-twisted wires 2i. By definition, the outer layer is composed of only one layer of the outer layer sub-twisted wire 2o. On the other hand, the inner layer may be composed of only one layer of the inner layer sub-twisted wire 2i or may be composed of a plurality of layers of the inner layer sub-twisted wires 2i.

[0032] Each sub-twisted wire 2 constituting the wire conductor 1 can be clearly confirmed, for example, as shown in FIGS. 3A to 3D, by visually observing while untwisting the wire conductor 1 with the sub-twisted wire 2 as a unit. When the wire conductor 1 has a parent twist structure, the parent twist structure may be eliminated. By untwisting the wire conductor 1 with the sub-twisted wire 2 as a unit, as shown in FIGS. 3A to 3D, the distinction between the outer layer sub-twisted wire 2o and the inner layer sub-twisted wire 2i, and the distinction between each layer when the inner layer sub-twisted wire 2i has a plurality of layers can also be clearly made.

[0033] In the wire conductor 1 according to the present embodiment, the ratio of the number of the individual wires 3 constituting the outer layer to the number of the individual wires 3 constituting the inner layer is within a predetermined range. Here, the total number of the individual wires 3 constituting the outer layer sub-twisted wire 2o, that is, the total number of the individual wires 3 included in the outer layer is defined as the outer layer wire number (N o ) and the total number of the individual wires 3 constituting the inner layer sub-twisted wire 2i, that is, the total number of the individual wires 3 included in the inner layer is defined as the inner layer wire number (N ibe set as such. And the number of inner-layer strands N i to the number of outer-layer strands N o The ratio (N o / N i ) is defined as the strand ratio. In the wire conductor 1 according to the present embodiment, this strand ratio is 2.0 or more. That is, the number of strands 3 constituting the inner layer is half or less of the number of strands 3 constituting the outer layer.

[0034] Generally, in a wire conductor, when adopting a stranding structure, the number of strands constituting each of the plurality of stranding wires is made the same. Also in the wire conductor 1 according to the present embodiment, it is preferable from the viewpoint of simplicity of the configuration of the wire conductor 1 to make the number of strands 3 constituting each of the plurality of stranding wires 2 the same. In this case, the ratio of the number of outer-layer stranding wires 2o to the number of inner-layer stranding wires 2i is equal to the above-mentioned strand ratio. That is, in the wire conductor 1 according to the present embodiment, the ratio of the number of outer-layer stranding wires 2o to the number of inner-layer stranding wires 2i is 2.0 or more. Hereinafter, unless otherwise specified, a form in which the number of strands 3 constituting each of the plurality of stranding wires 2 is the same will be dealt with. In the form shown in FIG. 1, the number of outer-layer stranding wires 2o is 12, and the number of inner-layer stranding wires 2i is 4, and their ratio, that is, the strand ratio, is 12 / 4 and is 3.

[0035] In the wire conductor 1 according to the present embodiment, the strand ratio is 2.0 or more, and the number of strands 3 constituting the inner layer is kept small. Therefore, in the inner part of the wire conductor 1, the packing density of the strands 3 is kept small, and a gap is easily secured between the strands 3. As a result, when the wire conductor 1 is bent, the strands 3 can easily move inside the wire conductor 1, and high flexibility can be obtained in the wire conductor 1.

[0036] In particular, when the shaping of the wire conductor 1 into a flat shape is performed by applying a force by rolling or the like to a raw material stranded wire 9 formed by twisting a plurality of sub-stranded wires 8 into a substantially circular cross-section (or a substantially hexagonal cross-section; the same applies hereinafter) as shown in FIG. 2A, the effect of improving flexibility by setting the strand ratio to 2.0 or more becomes higher. Generally, when a force that causes deformation is applied to the wire conductor by rolling or the like using rollers, a large load is likely to be applied to the strands in the inner portion where a large number of strands are densely arranged in a limited space rather than the outer peripheral portion of the wire conductor. Then, in many cases, the strands in the inner portion of the wire conductor are likely to be densely packed with each other with deformation, and the shapes of the deformed strands are likely to fit into each other to form a state where the strands are in close contact with each other. In this way, in the state where the strands are densely packed and in close contact, it is difficult for the strands to cause relative movement. In addition, with the deformation of the strands, the material constituting the strands is likely to be hardened (work hardening). As a result of the restriction of the relative movement of these strands and the hardening of the material, the flexibility of the wire conductor is reduced. However, in the wire conductor 1 according to the present embodiment, since the number of inner layer strands is suppressed to 2.0 or less in terms of the strand ratio, even when a force is applied by rolling or the like during flattening, the force applied to each strand 3 in the inner layer is suppressed to be small, and the degree of densification and close contact of the strands 3 and the hardening of the constituent material are reduced. As a result, the flexibility of the wire conductor 1 is maintained, and it can be flexibly bent and deformed.

[0037] Thus, in the wire conductor 1 according to this embodiment, since the strand ratio is 2.0 or more and the number of inner layer strands is kept small relative to the number of outer layer strands, a high degree of flexibility can be obtained from both the effect that the degree of freedom of relative movement of the strands 3 is high and the effect that hardening due to deformation of the strands 3 is suppressed. From the viewpoint of particularly enhancing the effect of improving flexibility, the strand ratio is particularly preferably 2.5 or more, and further preferably 3.0 or more. As described above, the flatness ratio w / h of the flat shape of the wire conductor 1 is preferably 3 or more, and further preferably 5 or more. However, if the strand ratio is 2.0 or more, even when the wire conductor 1 is formed into such a highly flat shape, the flexibility of the wire conductor 1 can be ensured at a high level. The upper limit of the strand ratio is not particularly defined, but for example, a form in which the strand ratio is 3.5 or less can be exemplified. When priority is given to improving the flexibility of the wire conductor 1, a form in which the strand ratio is 3.0 or more is also preferable. However, when priority is given to maintaining the stability of the flat shape in addition to a certain degree of flexibility, it is advisable to keep the strand ratio suppressed to about 3.0 or less.

[0038] As described above, when forming the flat wire conductor 1 by deforming the raw material stranded wire 9, the arrangement of the sub-stranded wires 8 in the raw material stranded wire 9 is inherited by the wire conductor 1 after flattening. That is, in the raw material stranded wire 9 shown in Fig. 2A, the raw material outer layer sub-stranded wire 8o located on the outer peripheral portion and the raw material inner layer sub-stranded wire 8i located inside the raw material outer layer sub-stranded wire 8o become the outer layer sub-stranded wire 2o and the inner layer sub-stranded wire 2i, respectively, in the wire conductor 1 after flattening. Therefore, in accordance with the desired strand ratio in the wire conductor 1 after flattening, the number of the raw material outer layer sub-stranded wire 8o and the raw material inner layer sub-stranded wire 8i may be set in the raw material stranded wire 9. The ratio of the number of the raw material inner layer sub-stranded wire 8i to the number of the raw material outer layer sub-stranded wire 8o directly becomes the ratio of the number of the inner layer sub-stranded wire 2i to the number of the outer layer sub-stranded wire 2o in the wire conductor 1 after flattening. Further, when the number of the strands 3 constituting each sub-stranded wire 8 in the raw material stranded wire 9 is the same, that ratio directly becomes the strand ratio in the wire conductor 1.

[0039] In the raw material twisted wire 9 shown in Fig. 2A, there are 4 inner-layer sub-twisted wires 8i of the raw material and 12 outer-layer sub-twisted wires 8o of the raw material. By deforming this raw material twisted wire 9 into a flat shape, as shown in Fig. 1, 4 inner-layer sub-twisted wires 2i and 12 outer-layer sub-twisted wires 2o can be obtained, and an electric wire conductor 1 with a strand ratio of 3 can be obtained. On the other hand, Fig. 2B shows a raw material twisted wire 9' composed of a conventional general electric wire conductor with a substantially circular cross-section in which the sub-twisted wires 8 are most densely packed in concentric layers. Here, as the inner-layer sub-twisted wires 8i of the raw material, a total of 7 sub-twisted wires 8 including 1 sub-twisted wire 8 arranged at the center and 6 sub-twisted wires 8 arranged in a single circle with the closest packing outside it are included. And as the outer-layer sub-twisted wires 8o of the raw material, 12 sub-twisted wires 8 arranged in a single circle with the closest packing on the outer periphery are further included. When this raw material twisted wire 9' is deformed into a flat shape, there are 12 outer-layer sub-twisted wires 2o and 7 inner-layer sub-twisted wires 2i, and the strand ratio becomes 12 / 7, which is 1.71. This strand ratio is less than 2.0. As will also be shown in the subsequent examples, in an electric wire conductor with a strand ratio less than 2.0 in this way, the flexibility tends to be low. That is, when a conventional general electric wire conductor in which the sub-twisted wires 8 are arranged with the closest packing is used as the raw material twisted wire 9' and flattened, it is difficult to obtain high flexibility.

[0040] As described above, the inner layer may be composed of only one layer of inner-strand twisted wires 2i, or the inner-strand twisted wires 2i may be composed of multiple layers. Here, assuming a case where two layers of inner-strand twisted wires 2i are arranged and one layer of outer-strand twisted wires 2o is arranged on the outer periphery thereof, the layer configuration of the strand twisted wires 2 in the wire conductor 1 will be denoted as "a - b - c". Here, a is the number of strand twisted wires 2 constituting the inner layer of the two inner layers, b is the number of strand twisted wires 2 constituting the outer layer of the two inner layers, and c is the number of strand twisted wires 2 constituting the outer layer (b ≠ 0, c ≠ 0). When the inner layer consists of only one layer, a = 0, and the number of strand twisted wires 2 constituting the one inner layer is denoted as b. When the layer configuration is expressed in this way, the number of inner-strand twisted wires 2i is a + b, and the ratio of the number of outer-strand twisted wires 2o to the number of inner-strand twisted wires 2i, that is, the strand ratio, is c / (a + b). The layer configuration of the wire conductor 1 shown in FIG. 1 formed from the raw material twisted wire 9 shown in FIG. 2A is denoted as "0 - 4 - 12". On the other hand, the layer configuration of the wire conductor formed from the raw material twisted wire 9' shown in FIG. 2B is denoted as "1 - 6 - 12".

[0041] In the present embodiment, as shown in FIG. 1 for the flattened wire conductor 1 and FIG. 2A for the raw material twisted wire 9, a form in which only one layer (one turn) of inner-strand twisted wires 2i is provided on the inner circumference of the outer-strand twisted wires 2o, that is, a form having a layer configuration of "0 - b - c" is preferable. Then, it is possible to easily achieve a low value of the strand ratio by reducing the number of inner-strand twisted wires 2i, and the flexibility of the wire conductor 1 can be effectively enhanced. For the same reason, when the inner layer is composed of multiple layers of inner-strand twisted wires 2i it is also preferable to keep the number of the layers at two. As the inner layer of the two-layer structure, a form in which a layer composed of a plurality of inner-strand twisted wires 2i is arranged on the outer circumference of one inner-strand twisted wire 2i, that is, a form having a layer configuration of "1 - b - c" is preferable. The values of b and c are not particularly specified and may be appropriately set in consideration of the required conductor cross-sectional area and the like. As b, a range of 4 or more and 6 or less can be preferably adopted. In that case, as c, a range of 8 or more and 12 or less can be preferably adopted. Examples of particularly suitable layer configurations include "0 - 4 - 8", "0 - 6 - 12", "0 - 4 - 12", etc. In particular, the layer configuration of "0 - 4 - 12" is preferable.

[0042] As described above, the wire conductor 1 according to the present embodiment has high flexibility by suppressing the number of the strands 3 constituting the inner layer so that the strand ratio is 2.0 or more. The flexibility of the wire conductor 1 can be evaluated, for example, by the repulsive force when the wire conductor 1 is bent. The smaller the repulsive force generated when the wire conductor 1 is bent at a predetermined bending radius, the higher the flexibility of the wire conductor 1 is shown. For example, it is preferable that the repulsive force of the wire conductor 1 (the target conductor) according to the embodiment of the present disclosure being focused on is smaller than the repulsive force of the reference conductor obtained by forming the raw material strand 9 in which the child strands 8 are most densely packed as shown in FIG. 2B into a flat shape. It is more preferable that the repulsive force of the target conductor is 99% or less, further 95% or less, 90% or less, 85% or less of the repulsive force of the reference conductor. Here, the reference conductor may be made of the same material as the target conductor and formed into a flat shape having the same flat ratio as the target conductor with a raw material strand having a most densely packed structure having the same conductor cross-sectional area. Further, the repulsive force may be measured in a state of an insulated wire in which an insulating coating having the same material and thickness is formed on the reference conductor and the target conductor, and the two may be compared. Usually, since the insulating coating has higher flexibility than the wire conductor, the contribution of the insulating coating can be ignored in the comparison of the repulsive forces.

[0043] In the wire conductor 1 according to the present embodiment, the improvement in flexibility by increasing the strand ratio is obtained by both the effects of ensuring the ease of relative movement of the strands 3 and suppressing the hardening of the strands 3 as described above. Among these, the degree of hardening of the strands 3 is reflected in the conductor resistance of the wire conductor 1. In copper and copper alloys, as well as aluminum and aluminum alloys, when work hardening occurs, the conductor resistance often increases. Therefore, it can be evaluated that the greater the conductor resistance, the greater the degree of hardening of the strands 3 due to the application of a load in the wire conductor 1. Preferably, the increase amount of the conductor resistance compared with the raw material strand 9 is suppressed to 22% or less, further 18% or less. Further, it is preferable that the conductor resistance of the wire conductor 1 is smaller than the conductor resistance of the reference conductor.

Example

[0044] Examples are shown below. Note that the present invention is not limited by these examples. Here, regarding an insulated wire having a flat wire conductor, the relationship between the strand ratio and flexibility was examined. In the following, the preparation of samples and each evaluation are carried out at room temperature in the air.

[0045] (Preparation of Samples) First, wire conductors constituting Samples A1 to A5 and Samples B1 to B5 were prepared. First, a plurality of aluminum alloy strands were twisted together to form a sub-strand, and then the same sub-strands were twisted together to obtain a raw material strand with a substantially circular cross-section. The raw material strand was rolled into a flat shape by a roller to produce a flat wire conductor. The layer configuration of the sub-strands was varied depending on the sample as shown in Tables 1 and 2 respectively. In each sample, the layer configuration of the wire conductor after flattening is the same as that of the raw material strand. In any sample, in the state of the raw material strand, the outer diameter of the strands was set so that the conductor cross-sectional area would be 62.0 ± 0.6 mm 2 depending on the number of strands (number of sub-strands). The flat ratio of the wire conductor was controlled by the magnitude of the force applied to the raw material strand from the roller, with a flat ratio of 5 for Samples A1 to A5 and a flat ratio of 6 for Samples B1 to B5.

[0046] An insulating coating was formed on the outer periphery of each wire conductor prepared above to produce an insulated wire. As the insulating coating, polyolefin was used as the material, and a coating layer with a thickness of 0.6 mm was formed by extrusion molding.

[0047] (Evaluation of the State of the Wire Conductor) Regarding the wire conductors of each sample, it was confirmed whether the strand structure was maintained and whether the layer configuration set by the arrangement of the sub-strands in the raw material strand was maintained even after flattening. Specifically, at the end of the wire conductor after flattening, the strand structure was eliminated with the sub-strand as a unit, and the distribution of the sub-strands was observed. From this observation, it was confirmed that in the wire conductor after flattening, the strand structure and the predetermined layer configuration set in the raw material strand were maintained and constituted the outer layer and the inner layer.

[0048] Furthermore, the insulated wires of each sample were embedded in an acrylic resin and cut along a cross-section perpendicular to the axial direction to create cross-sectional samples. By observing these cross-sectional samples, it was confirmed that the wire conductors were formed into a flat shape with a predetermined aspect ratio. Also, the cross-sectional area of the conductor was determined from the conductor weight.

[0049] (Measurement of repulsive force) The insulated wires of each sample were cut out to a length of 400 mm, and both ends were gripped by gripping tools, and the insulated wires were bent. At this time, the bending radius (R) was set to 40 mm, and in the state of being bent up to 135°, the load applied to the end of the insulated wire was measured by a load cell attached to the gripping tool. The measured value of this load was recorded as the repulsive force.

[0050] (Measurement of conductor resistance) The conductor resistance of each sample was measured with a resistance meter.

[0051] (Evaluation results) First, as representatives, for Samples A2 and A5, the results of confirming the structure and distribution of the strand wires by eliminating the twisting structure in units of strand wires at the ends of the wire conductors are shown. Due to the layer configuration in the raw material strand wires, a layer configuration of "1-6-12" was set for Sample A2, and a layer configuration of "0-4-12" was set for Sample A5. Photographs taken of these samples in a state where the twisting structure was eliminated in units of strand wires are shown in FIGS. 3A to 3D. FIGS. 3A and 3B are photographs of Sample A2, and FIGS. 3C and 3D are photographs of Sample A5. FIGS. 3A and 3C show the state where the outer layer twisting structure was eliminated, and FIGS. 3B and 3D show the state where the outer layer was completely removed and then the inner layer twisting structure was eliminated.

[0052] According to these photos, in both Sample A2 and A5, a plurality of strands corresponding to the sub-twisted strands are confirmed, and it can be seen that the structure of the sub-twisted strands formed by twisting a plurality of strands is clearly maintained even after being flattened. Also, the arrangement of these sub-twisted strands maintains a state clearly divided into an outer layer (O) and an inner layer (I). In particular, in the inner layer of Sample A2 shown in Fig. 3B, a two-layer structure of the inner layer (I) can be confirmed, and one sub-twisted strand (II) constituting the innermost layer is distinguished from the other sub-twisted strands arranged on its outer periphery. From such a distribution of sub-twisted strands, it is confirmed that a flat wire conductor is obtained while maintaining the predetermined layer configuration set in the raw material twisted strand. That is, in the wire conductor after flattening, the layer configuration of "1-6-12" is maintained in Sample A2, and the layer configuration of "0-4-12" is maintained in Sample A5. For other samples as well, it was similarly confirmed that the sub-twisted structure and the layer configuration set in the raw material twisted strand are also inherited by the wire conductor after flattening.

[0053] Furthermore, based on the photos of the cross-sectional samples, the internal structure of the flattened wire conductor is examined. Here, as representatives, the examination results for Samples A2, A5, B2, and B5 are shown. Samples A2 and B2 have a layer configuration of "1-6-12", and Samples A5 and B5 have a layer configuration of "0-4-12". Also, the flat ratio is 5 for Samples A2 and A5, and the flat ratio is 6 for Samples B2 and B5.

[0054] Figures 4A to 4D respectively show cross-sectional photographs of the above-mentioned samples A2, A5, B2, and B5. In each cross-sectional photograph, it can be confirmed that the wire conductor is formed into a flat shape having a predetermined aspect ratio. In any of the wire conductors, it is confirmed that the strands in the inner region are greatly deformed compared to the outer peripheral portion, particularly the regions on both sides in the width direction. However, it can be seen that in sample A5 compared to sample A2, and in sample B5 compared to sample B2, the degree of deformation of the strands in the inner portion is smaller, and a gap is secured between the strands in the inner portion. The strand ratio of the wire conductor is 1.71 (12 / 7) for samples A2 and B2, and 3 (12 / 4) for samples A5 and B5. That is, the above-mentioned tendency confirmed in the cross-sectional photograph indicates that by increasing the strand ratio and reducing the number of strands in the inner layer with respect to the outer layer, the deformation and densification of the strands in the inner layer are alleviated. It was confirmed that each sample other than the above-mentioned samples A2, A5, B2, and B5 has a similar tendency. In the cross-sectional sample, due to the operations of embedding in the acrylic resin and cutting, the structure and distribution of the stranding in the wire conductor become difficult to understand. As shown in FIGS. 3A to 3D, the structure and distribution of the stranding as confirmed while eliminating the twisting structure of the wire conductor cannot be clearly recognized in the cross-sectional photograph.

[0055] Next, Table 1 and Table 2 respectively show the layer configuration, strand ratio, and the results of each evaluation for samples A1 to A5 with an aspect ratio of 5 and samples B1 to B5 with an aspect ratio of 6. Regarding the conductor cross-sectional area, the rate of change from the raw material stranding is also shown in parentheses. Further, FIGS. 5A and 5B respectively illustrate the relationship between the strand ratio and the repulsive force for samples A1 to A5 and samples B1 to B5. An approximate straight line is also shown in the figure. Also, the sample numbers are entered near each plot point.

[0056]

Table 1

[0057]

Table 2

[0058] According to Tables 1, 2 and FIGS. 5A and 5B, it can be seen that regardless of the aspect ratio adopted, the larger the strand ratio, the lower the repulsive force and the higher the flexibility. As explained above based on the cross-sectional photographs of FIGS. 4A to 4D, this can be interpreted as a result of the increase in the strand ratio and the decrease in the number of inner-layer strands relative to the number of outer-layer strands, which relaxes the high density and deformation of the strands in the inner layer. That is, when the high density and deformation of the strands in the inner layer are relaxed, the relative movement of the strands is likely to occur and the hardening of the constituent material is less likely to occur, so it is considered that high flexibility can be obtained in the wire conductor. By setting the strand ratio to 2.0 or more as in Samples A3 to A5 and B3 to B5, the repulsive force can be reduced compared with the wire conductors (Samples A2 and B2) having a layer structure of "1-6-12" formed from a raw material stranded wire in which a conventional general child stranded wire is most densely filled. In particular, in Samples A5 and B5 where the strand ratio is 3, the repulsive force is significantly reduced.

[0059] Looking at the measurement results of the conductor resistance in Tables 1 and 2, generally, the larger the strand ratio, the smaller the conductor resistance tends to be. The magnitude of the conductor resistance is an index reflecting the application of the load to the wire conductor due to the processing during flattening and the degree of hardening of the strands thereby, and the small conductor resistance indicates that the application of the load and the degree of hardening of the strands are small. That is, in the region where the strand ratio is large, the hardening of the strands is reduced, and it can be said that this contributes to the improvement of flexibility in combination with the effect of the ease of relative movement of the strands. The conductor resistance of the raw material stranded wire is 0.43 mΩ / m, and in any sample, the conductor resistance of the wire conductor after flattening has increased from the state of the raw material stranded wire, but in the samples with a large strand ratio, the increase range is suppressed to be small.

[0060] Finally, when comparing the evaluation results for the case of aspect ratio 5 (Samples A1 to A5) and the case of aspect ratio 6 (Samples B1 to B5), in the case of aspect ratio 6, the amount of load applied to the conductor during flattening is larger, and this is reflected in the larger reduction rate of the conductor cross-sectional area and the higher conductor resistance. However, in the case of aspect ratio 6, the tendency for the conductor resistance to be suppressed to a smaller value when the strand ratio is increased becomes more prominent. On the other hand, the effect of reducing the repulsive force by increasing the strand ratio is obtained to the same extent for any aspect ratio. In particular, for Samples A5 and B5 where the strand ratio is 3, similarly small repulsive forces are measured.

[0061] As described above, the embodiments of the present disclosure have been described in detail. However, the present invention is not limited to the above embodiments in any way, and various modifications are possible without departing from the gist of the present invention.

Explanation of Reference Numerals

[0062] 1 Electric wire conductor 2 Stranded wire 2i Inner-layer stranded wire 2o Outer-layer stranded wire 3 Strand 8 Stranded wire 8i Raw material inner-layer stranded wire 8o Raw material outer-layer stranded wire 9 Raw material stranded wire 9’ Raw material stranded wire (conventional form) h Height w Width

Claims

1. An electric wire conductor configured as a stranded wire including a plurality of sub-stranded wires formed by twisting a plurality of individual strands, wherein a cross-section intersecting the axial direction of the stranded wire has a flat portion having a flat shape in which the dimension in the width direction is larger than the dimension in the height direction, in the flat portion, among the sub-stranded wires, the total number of the individual strands constituting the outer layer sub-stranded wires arranged on the outer periphery of the flat portion is defined as the number of outer layer individual strands, and the total number of the individual strands constituting the inner layer sub-stranded wires arranged inside the outer layer sub-stranded wires is defined as the number of inner layer individual strands, the ratio of the number of outer layer individual strands to the number of inner layer individual strands is 2.0 or more, the electric wire conductor has an inner layer in which the inner layer sub-stranded wires are arranged in only one layer or two layers, and an outer layer in which one layer of the outer layer sub-stranded wires is arranged on the outer periphery of the inner layer, let a be the number of the sub-stranded wires constituting the inner layer of the two inner layers, b be the number of the sub-stranded wires constituting the outer layer of the two inner layers, and c be the number of the sub-stranded wires constituting the outer layer, an electric wire conductor, wherein a is 0 or 1, b is 4 or more and 6 or less, and c is 8 or more and 12 or less. However, when the inner layer consists of only one layer, a is set to 0, and the number of the sub-stranded wires constituting the one-layer inner layer is set to b.

2. the number of the individual strands constituting each of the plurality of sub-stranded wires is the same, the ratio of the number of the outer layer sub-stranded wires to the number of the inner layer sub-stranded wires is 2.0 or more, the electric wire conductor according to claim 1.

3. the ratio of the number of outer layer individual strands to the number of inner layer individual strands is 3.0 or more, the electric wire conductor according to claim 1.

4. the inner layer sub-stranded wires are provided in only one layer on the inner periphery of the outer layer sub-stranded wires, the electric wire conductor according to claim 1.

5. in the cross-section of the electric wire conductor, the dimension in the width direction is 5 times or more the dimension in the height direction, the electric wire conductor according to claim 1.

6. The ratio of the number of outer layer individual strands to the number of inner layer individual strands is 3.5 or less, the electric wire conductor according to claim 1.

7. The conductor cross-sectional area is 16 mm2 or more, the electric wire conductor according to claim 1.

8. At least a part of the individual strands has a cross-sectional shape deformed from a circular shape, the deformation rate of the individual strands from the circular shape is smaller in the inner side portion than in the outer peripheral portion of the cross-section of the electric wire conductor, the electric wire conductor according to claim 1.

9. An insulated electric wire having the electric wire conductor according to any one of claims 1 to 8, and an insulating coating covering the outer periphery of the electric wire conductor.

10. A wire harness comprising the insulated electric wire according to Claim 9.

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