Electric wire conductor, insulating wire, and wire harness

Abstract

To provide an electric wire conductor that is an electric wire conductor obtained by forming stranded wires of strands into a flat shape and can secure high flexibility, and an insulating electric wire and a wire harness provided with such electric wire conductors.SOLUTION: An electric wire conductor 1 is configured as a stranded wire including a plurality of child strands 2 each formed by twisting together a plurality of strands 3, and a cross section of the strands 2 intersecting the axial direction has a flat portion having a flat shape with a width dimension w greater than a height dimension h, and in the flat portion, the total number of strands 3 constituting an outer layer child strand 2o of the child strands 2 arranged on the outer periphery of the flat portion is defined as the number of outer layer strands, and the total number of strands 3 constituting an inner layer child strand 2i arranged more inward than the outer layer child strand 2o is defined as the number of inner layer strands, and the ratio of the number of outer layer strands to the number of inner layer strands is 2.0 or greater.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A flat cable made of a flat conductor is known, and the use of the flat cable can reduce the space occupied when routing the cable compared to a typical electric wire having a conductor with a substantially circular cross section.

[0003] In conventional general flat cables, rectangular conductors are often used as the electric wire conductor, as disclosed in Patent Documents 1 and 2. A rectangular conductor is a metal solid wire formed into a rectangular cross section. In addition, Patent Documents 3 and 4 filed by the applicant disclose an electric wire conductor 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 / 177016 [Patent Document 5] Japanese Patent Application Publication No. 158710 / 1983 [Patent Document 6] Japanese Patent Application Laid-Open No. 2009-087868 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Documents 3 and 4, using an electric wire conductor in which a stranded wire is formed into a flat shape can achieve space saving 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 strands constituting the stranded wire. The application of the load causes deformation of the strands. As also described in Patent Documents 3 and 4, deformation of the outermost strands of the electric wire conductor can be kept small, but the innermost strands are more likely to undergo deformation than the outermost strands. If the deformation of the strands becomes large, the strands may become crowded and tightly packed together, and the material constituting the strands may harden, potentially reducing the flexibility of the electric wire conductor. In particular, if the electric wire conductor is formed into a horizontally elongated, highly flat shape with the aim of reducing the height occupied by the electric wire conductor and improving space saving, the flexibility of the innermost strands may be reduced due to deformation.

[0006] Therefore, an object of the present invention is to provide an electric wire conductor in which stranded wires are twisted together and formed into a flat shape, and which can ensure high flexibility, as well as an insulated electric wire and a wire harness including such an electric wire conductor. [Means for solving the problem]

[0007] The electric conductor of the present disclosure is configured as a twisted wire including a plurality of child strands formed by twisting a plurality of strands together, and a cross section of the twisted wire intersecting the axial direction has a flat portion having a flat shape with a width dimension greater than a height dimension, and in the flat portion, the total number of strands constituting an outer layer child strand arranged on the outer periphery of the flat portion is defined as the number of outer layer strands, and the total number of strands constituting an inner layer child strand arranged more inward than the outer layer child strand is defined as the number of inner layer strands, and the ratio of the number of outer layer strands to the number of inner layer strands is 2.0 or more.

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

[0009] The electric conductor of the present disclosure is an electric conductor in which stranded wires are twisted together and formed into a flat shape, and can ensure high flexibility. Furthermore, an insulated electric wire and a wire harness of the present disclosure include such an electric conductor. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating a flat-shaped electric wire conductor according to one embodiment of the present disclosure. In the main view, the individual wires constituting the child strand are not shown, and an enlarged view enclosed in a rectangle illustrates a cross section of the child strand including the wires. [Figure 2] 2A and 2B are cross-sectional views showing raw material stranded wires for forming a flat conductor. Fig. 2A shows the raw material stranded wire that is the raw material for the electric conductor according to the embodiment of the present disclosure shown in Fig. 1, and Fig. 2B shows the raw material stranded wire configured as a conventional general stranded wire in which child strands are closely packed. [Figure 3] 3A to 3D are photographs showing the untwisted state of the prepared electric wire conductors of Samples A2 and A5. Figures 3A and 3C show the state of Samples A2 and A5, respectively, where the twisted structure of the outer layer has been untwisted on a child-stranded basis, and Figures 3B and 3D show the state of Samples A2 and A5, respectively, where the twisted structure of the inner layer has been untwisted on a child-stranded basis with the outer layer removed. [Figure 4] 4A to 4D are photographs of the cross sections of the conductors of representative samples, which are samples A2, A5, B2, and B5, respectively. [Figure 5] 5A and 5B are diagrams showing the relationship between the wire ratio and the repulsive force. Fig. 5A shows the case where the flattening ratio is 5, and Fig. 5B shows the case where the flattening ratio is 6. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. The electric wire conductor according to the present disclosure is configured as a twisted wire including a plurality of child strands each formed by twisting a plurality of strands together, and has a flat portion in a cross section intersecting the axial direction of the twisted wire, the cross section having a flat shape with a width dimension greater than a height dimension, and in the flat portion, the total number of strands constituting an outer layer child strand arranged on the outer periphery of the flat portion is defined as the number of outer layer strands, and the total number of strands constituting an inner layer child strand arranged more inward than the outer layer child strand is defined as the number of inner layer strands, and the ratio of the number of outer layer strands to the number of inner layer strands is 2.0 or more.

[0012] In the flattened portion of the conductor, the ratio of the number of outer layer wires to the number of inner layer wires is 2.0 or more. In other words, the number of wires constituting the inner portion is half or less of the number of wires constituting the outer portion of the conductor. Because the number of wires arranged inside the conductor is small, when the conductor is deformed into a flat shape by applying force to form the flattened portion, the wires located inside the conductor are less likely to deform due to the application of a large load. As a result, compared to when the number of wires arranged inside the conductor is large, the density and adhesion of the wires in the inner portion of the conductor is reduced, making it easier for the inner wires to move when the conductor is bent. Furthermore, the constituent materials are less likely to harden due to the deformation of the wires. As a result, the conductor has high flexibility.

[0013] Preferably, the number of strands constituting each of the plurality of child strands is the same, and the ratio of the number of the outer layer child strands to the number of the inner layer child strands is 2.0 or more. In this case, by using the same child strands throughout the entire conductor and setting the number of child strands to be arranged in the outer peripheral portion and the inner portion of the conductor, it is possible to obtain a conductor having a small number of strands constituting the inner portion and having high flexibility in the flat portion, as described above.

[0014] It is also preferable that the ratio of the number of outer layer wires to the number of inner layer wires is 3.0 or more, which makes it particularly easy to increase the flexibility of the electric wire conductor.

[0015] The inner layer stranded wire may be provided in only one layer around the outer layer stranded wire, which can effectively improve the flexibility of the conductor by reducing the number of wires constituting the inner portion, compared to when the inner layer stranded wire is provided in two or more layers.

[0016] In the cross section of the conductor, the dimension in the width direction is preferably five times or more the dimension in the height direction. This reduces the height occupied by the conductor, thereby improving space saving. The more highly flat the conductor is formed into, the greater the load applied to the wires constituting the inner portion, making the conductor more likely to lose flexibility. However, as described above, by setting the ratio of the number of outer layer strands to the number of inner layer strands to be 2.0 or more, high flexibility can be ensured even when such a highly flat shape is adopted.

[0017] An insulated wire according to the present disclosure includes the conductor and an insulating covering covering the outer periphery of the conductor. A wire harness according to the present disclosure also includes the insulated wire. These insulated wires and wire harnesses include the conductor, which has high flexibility due to a small number of wires arranged inside the conductor. Therefore, the insulated wire and wire harness as a whole can utilize this high flexibility.

[0018] [Details of the embodiments of the present disclosure] The following describes in detail electric conductors, insulated wires, and wire harnesses according to embodiments of the present disclosure with reference to the drawings. In this specification, concepts such as straight, parallel, and perpendicular, which indicate the shape and arrangement of components, with respect to the shape of each part of an electric conductor, include deviations from the geometric concepts, such as deviations of approximately ±15% in length and deviations of approximately ±15° in angle, within the range allowable for this type of electric conductor, insulated wire, and wire harness. In this specification, unless otherwise specified, the cross section of an electric conductor refers to a cross section cut perpendicular to the axial direction (longitudinal direction). Furthermore, various properties are values ​​evaluated at room temperature in the atmosphere.

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

[0020] The electric wire conductor 1 has a flat outer shape at least in a portion along the axial direction. That is, the electric wire conductor 1 has a flat portion in which a cross section perpendicular to the axial direction thereof is flat. In this embodiment, a form in which the entire axial area of ​​the electric wire conductor 1 has such a flat portion is discussed. Here, the cross section of the electric wire conductor 1 having a flat shape refers to a state in which the width w, which is the dimension of the longest straight line 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, is larger than the height h, which is the dimension of the straight line that is perpendicular to the longest straight line and includes the entire cross section.

[0021] The cross section of the electric wire conductor 1 may have any specific shape as long as it has a flat shape. Examples of flat shapes include a rectangle, an ellipse, an oval, an oval (a rectangle with semicircles at both ends), a parallelogram, and a trapezoid. If the circumscribed figure of the cross section can approximate each of these shapes, the cross section of the electric wire conductor 1 can be considered to have each of these shapes. Of the listed shapes, it is preferable to adopt one of a rectangle, an ellipse, an oval, and an oval. In the embodiment shown in FIG. 1, the electric wire conductor 1 has a cross section that can approximate an oval.

[0022] In the electric wire conductor 1, all of the wires 3 are not twisted together but are divided into multiple child strands 2. That is, multiple wires 3 are twisted together to form a child strand 2, and the electric wire conductor 1 is composed of a conductor wire including multiple child strands 2. In the main diagram of FIG. 1, the cross section of each child strand 2 is simplified and shown as a circle or ellipse with a solid line (outer layer child strand 2o) and a dashed line (inner layer child strand 2i). The cross section shown enclosed in a rectangle illustrates the structure of a child strand 2 including multiple wires 3. In the electric wire conductor 1, the multiple child strands 2 may simply be gathered into a bundle, but preferably have a parent twist structure in which multiple child strands 2 are twisted together. Each child strand 2 may have a cross section that approximates a circle or a cross-sectional shape that is deformed from a circle. In FIG. 1, the child strand (inner layer child strand) 2i in the inner part of the cross section is shown deformed into a flattened shape.

[0023] As will be described in detail later, the electric wire conductor 1 can be formed by rolling a raw stranded wire in which a plurality of child strands 2 are stranded together to have a substantially circular cross section. As the child strands 2 and at least some of the individual wires 3 that make up the electric wire conductor 1 are formed into a flat shape, the cross-sectional shape of the child strands 2 and the individual wires 3 may be deformed from a circular shape. The deformation rate of the child strands 2 and the individual wires 3 from a circular shape is often smaller at the outer periphery of the cross section of the electric wire conductor 1, particularly at both widthwise ends, than at the inner side. In the electric wire conductors of the examples shown in Figures 4A to 4D, the deformation rate of the individual wires on both widthwise ends is also smaller.

[0024] The electric wire including the electric wire conductor 1 according to this embodiment has a flat cross section, which allows it to reduce the space required for routing compared to an electric wire having an electric wire conductor with a substantially circular cross section but the same conductor cross section. In other words, the space around an electric wire where other electric wires or other components cannot be arranged can be reduced. In particular, the space occupied by the electric wire in the height direction can be reduced, making it easier to achieve space saving. Furthermore, since the electric wire conductor 1 is a stranded wire formed by twisting together multiple elemental wires 3, it has higher flexibility than a flat solid conductor with the same conductor cross section. The electric wire conductor 1 exhibits high flexibility, especially in the height direction. Thus, the flat shape of the electric wire conductor 1 allows it to achieve both high space saving and flexibility. Because an insulated electric wire or a wire harness including the electric wire conductor 1 has high space saving and flexibility, it is particularly suitable for applications requiring routing in narrow spaces or complex paths, such as inside an automobile.

[0025] From the viewpoint of particularly enhancing space-saving performance in the height direction, it is preferable that the width of the cross section of the conductor 1 is three times or more the height. In other words, it is preferable that the flatness ratio w / h is 3 or more. It is more preferable that the flatness ratio is 5 or more. Although there is no particular upper limit set for the flatness ratio of the conductor 1, it is preferable to keep it at about 8 or less from the viewpoint of avoiding application of excessive load to the conductor 1 when it is formed into a flat shape.

[0026] The material constituting the electric wire conductor 1 is not particularly limited, and various metal materials can be used. Typical metal materials constituting the electric wire conductor 1 include copper and copper alloys, and aluminum and aluminum alloys. In particular, aluminum and aluminum alloys have lower electrical conductivity than copper and copper alloys, so the conductor cross-sectional area tends to be larger to ensure the necessary electrical conductivity. Therefore, flattening the electric wire conductor 1 to improve space saving is more effective. Furthermore, the larger the conductor cross-sectional area, the greater the effect of ensuring flexibility by reducing the number of wires 3 included in the inner layer, as described below. From these perspectives, it is preferable to construct the electric wire conductor 1 from aluminum or an aluminum alloy.

[0027] From the same viewpoint, the conductor cross section is set to 16 mm 2 It is preferable that the conductor 1 is formed as an assembly of a plurality of child strands 2, rather than as a bundle of a plurality of stranded wires 3. This allows the stranding of the wires 3 and the forming into a flat shape to be carried out efficiently even if the conductor cross-sectional area is large. Although there is no particular upper limit to the conductor cross-sectional area, it is preferable to set the conductor cross-sectional area to, for example, 300 mm 2 It is preferable to keep the outer diameter of the wires 3 constituting the electric conductor 1 within the range of 0.12 mm or more and 0.5 mm or less. The outer diameter of the wires 3 constituting the electric conductor 1 is not particularly limited either, but can be exemplified as being in the range of 0.12 mm or more and 0.5 mm or less. It is preferable that the wires 3 constituting the electric conductor 1 are the same, that is, made of the same material and have the same outer diameter.

[0028] An insulated wire according to an embodiment of the present disclosure includes a conductor 1 and an insulating coating (not shown). The insulating coating covers the entire outer periphery of the conductor 1. The material constituting the insulating coating is not particularly limited as long as it is an insulating material, but it is preferable that the insulating coating be based on an organic polymer. Examples of organic polymers include olefin-based polymers such as polyolefins and olefin-based copolymers, halogen-based polymers such as polyvinyl chloride, various elastomers, rubber, etc. The organic polymer may be crosslinked or foamed. Furthermore, 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. In this case, the specific arrangement structure of the plurality of insulated electric wires is not particularly limited, but a preferred example is a form in which the 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 arranged plurality of insulated electric wires are uniform.

[0030] <Details of the wire conductor configuration> As described above, the electric wire conductor 1 according to the embodiment of the present disclosure includes a plurality of child strands 2 each formed by twisting together a plurality of wires 3. In the electric wire conductor 1, the child strands 2 are arranged in layers. Here, "layered" refers to a state in which the child strands 2 are arranged in a substantially annular shape, with multiple layers extending along the direction connecting the outer periphery and the center of the electric wire conductor 1 (the same applies below when specifying the number of layers of the child strands 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 electric wire conductor 1, the child strands 2 arranged on the outer periphery of the flat cross section constitute the outer layer as outer layer child strands 2o. The child strands 2 arranged more inward in the cross section than the outer layer child strands 2o constitute the inner layer as inner layer child strands 2i. All child strands 2 located more inward than the outer layer child strands 2o are inner layer child strands 2i. By definition, the outer layer is composed of only one layer of outer layer child strands 2o. On the other hand, the inner layer may be composed of only one layer of inner layer child strands 2i, or the inner layer may be composed of multiple layers of inner layer child strands 2i.

[0032] Each child strand 2 constituting the electric wire conductor 1 can be clearly confirmed by visually observing the child strand 2 as a unit while untwisting the electric wire conductor 1, for example, as shown in Figures 3A to 3D. If the electric wire conductor 1 has a parent strand structure, the parent strand structure can be untwisted. By untwisting the electric wire conductor 1 in units of child strands 2, it is possible to clearly distinguish between the outer layer child strand 2o and the inner layer child strand 2i, as well as between each layer if the inner layer child strand 2i has multiple layers, as shown in Figures 3A to 3D.

[0033] In the electric conductor 1 according to this embodiment, the ratio of the number of wires 3 constituting the outer layer to the number of wires 3 constituting the inner layer is within a predetermined range. Here, the total number of wires 3 constituting the outer layer stranded wire 2o, i.e., the total number of wires 3 included in the outer layer, is referred to as the outer layer wire count (N o ), and the total number of wires 3 constituting the inner layer strand 2i, that is, the total number of wires 3 included in the inner layer, is defined as the number of inner layer wires (N i) and the number of inner layer wires N i Number of outer layer wires N o The ratio (N o / N i ) is the strand ratio. In the electric conductor 1 according to this embodiment, this strand ratio is 2.0 or more. In other words, 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, when a child stranding structure is employed in an electric conductor, the number of strands 3 constituting each of the multiple child strands is the same. In the electric conductor 1 according to this embodiment, it is also preferable to make the number of strands 3 constituting each of the multiple child strands 2 the same from the viewpoint of simplifying the structure of the electric conductor 1. In this case, the ratio of the number of outer layer child strands 2o to the number of inner layer child strands 2i is equal to the above-mentioned strand ratio. That is, in the electric conductor 1 according to this embodiment, the ratio of the number of outer layer child strands 2o to the number of inner layer child strands 2i is 2.0 or more. Hereinafter, unless otherwise specified, a configuration in which the number of strands 3 constituting each of the multiple child strands 2 is the same is referred to. In the configuration shown in FIG. 1, the number of outer layer child strands 2o is 12 and the number of inner layer child strands 2i is 4, and the ratio between them, i.e., the strand ratio, is 12 / 4, or 3.

[0035] In the conductor 1 according to this embodiment, the strand ratio is 2.0 or more, and the number of strands 3 constituting the inner layer is kept small. Therefore, the packing density of the strands 3 is kept low in the inner part of the conductor 1, and gaps are easily secured between the strands 3. As a result, when the conductor 1 is bent, the strands 3 are easily movable inside the conductor 1, and the conductor 1 has high flexibility.

[0036] In particular, when the flattening of the electric wire conductor 1 is performed by applying a force, such as by rolling, to a raw stranded wire 9, which is made by twisting together multiple child strands 8 into a substantially circular cross-section (or a substantially hexagonal cross-section; the same applies below), as shown in FIG. 2A , a strand ratio of 2.0 or more is highly effective in improving flexibility. Generally, when a force that causes deformation is applied to the electric wire conductor by rolling using rollers, a larger load is likely to be applied to the wires in the inner portion of the electric wire conductor, where many wires are densely arranged in a limited space, than to the outer periphery of the electric wire conductor. In many cases, this causes the wires in the inner portion of the electric wire conductor to become densely packed together due to deformation, and the deformed wire shapes tend to fit into each other, forming a state in which the wires are closely packed together. In this densely packed and closely packed state, the wires are less likely to move relative to each other. Additionally, the material that constitutes the wires is likely to harden as the wires deform (work hardening). The restriction of the relative movement of these wires and the hardening of the material result in a decrease in the flexibility of the conductor. However, in the conductor 1 according to this embodiment, the number of inner layer wires is kept to a wire ratio of 2.0 or less. Therefore, even if a force is applied by rolling or the like during flattening, the force applied to each wire 3 in the inner layer is kept small, reducing the density and adhesion of the wires 3 and the hardening of the constituent material. As a result, the flexibility of the conductor 1 is maintained, allowing it to be flexibly bent and deformed.

[0037] As described above, in the conductor 1 according to this embodiment, the strand ratio is set to 2.0 or more, and the number of inner-layer strands is kept small relative to the number of outer-layer strands. This allows for a high degree of freedom of relative movement of the strands 3, and also suppresses hardening due to deformation of the strands 3, resulting in high flexibility. To further enhance the effect of improving flexibility, the strand ratio is preferably 2.5 or more, and even more preferably 3.0 or more. As described above, the flattening ratio w / h of the flat shape of the conductor 1 is preferably 3 or more, and even more preferably 5 or more. However, if the strand ratio is set to 2.0 or more, high flexibility of the conductor 1 can be ensured even when the conductor 1 is formed into such a highly flattened shape. While there is no particular upper limit to the strand ratio, an example is a strand ratio of 3.5 or less. If priority is given to improving the flexibility of the electric wire conductor 1, it is preferable to set the strand ratio to 3.0 or more. However, if priority is given to maintaining a stable flat shape in addition to a certain degree of flexibility, it is advisable to keep the strand ratio at approximately 3.0 or less.

[0038] As described above, when the flattened conductor 1 is formed by deforming the raw material stranded wire 9, the arrangement of the child strands 8 in the raw material stranded wire 9 is carried over to the flattened conductor 1. That is, in the raw material stranded wire 9 shown in FIG. 2A , the raw material outer layer child strands 8o located on the outer periphery and the raw material inner layer child strands 8i located inside the raw material outer layer child strands 8o become the outer layer child strands 2o and the inner layer child strands 2i, respectively, in the flattened conductor 1. Therefore, the numbers of the raw material outer layer child strands 8o and the raw material inner layer child strands 8i in the raw material stranded wire 9 may be set in accordance with the strand ratio desired in the flattened conductor 1. The ratio of the number of raw inner layer stranded wires 8i to the number of raw outer layer stranded wires 8o is directly equivalent to the ratio of the number of inner layer stranded wires 2i to the number of outer layer stranded wires 2o in the flattened electric wire conductor 1. Furthermore, if the number of strands 3 constituting each stranded wire 8 in the raw material stranded wire 9 is the same, this ratio is directly equivalent to the strand ratio in the electric wire conductor 1.

[0039] The raw material stranded wire 9 shown in Figure 2A has four inner layer child strands 8i and twelve outer layer child strands 8o. By deforming this raw material stranded wire 9 into a flat shape, an electric conductor 1 can be obtained with four inner layer child strands 2i and twelve outer layer child strands 2o, as shown in Figure 1, and a strand ratio of 3. On the other hand, Figure 2B shows a raw material stranded wire 9' made of a conventional electric conductor with a generally circular cross section, in which child strands 8 are closely packed in concentric layers. Here, the raw material inner layer child stranded wire 8i includes one child strand 8 arranged in the center and six child strands 8 arranged in a closely packed manner around it, for a total of seven child strands 8. The raw material outer layer child stranded wire 8o includes an additional 12 child strands 8 arranged in a closely packed manner around the outer periphery. When this raw stranded wire 9' is deformed into a flattened shape, the number of outer layer child strands 2o becomes 12 and the number of inner layer child strands 2i becomes 7, resulting in a strand ratio of 12 / 7, or 1.71. This strand ratio is less than 2.0. As will be shown in the examples below, electric conductors with strand ratios less than 2.0 like this tend to have low flexibility. In other words, when a conventional electric conductor in which the child strands 8 are arranged in a close-packed manner is used as the raw stranded wire 9' and flattened, it is difficult to achieve high flexibility.

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

[0041] In this embodiment, as shown in FIG. 1 and FIG. 2A, the flattened electric conductor 1 and the raw stranded wire 9 are preferably configured such that only one layer (one turn) of inner layer stranded wire 2i is provided around the outer layer stranded wire 2o, i.e., a "0-bc" layer configuration is used. This allows for a simple reduction in the strand ratio by reducing the number of inner layer stranded wires 2i, and effectively improves the flexibility of the electric conductor 1. For the same reason, even when the inner layer is configured with multiple inner layer stranded wires 2i, it is preferable to limit the number of layers to two. For a two-layer inner layer, a layer of multiple inner layer stranded wires 2i is preferably arranged around a single inner layer stranded wire 2i, i.e., a "1-bc" layer configuration is used. The values ​​of b and c are not particularly specified and may be set appropriately taking into account the required conductor cross-sectional area, etc., but b can be suitably set within the range of 4 to 6. In this case, c can be suitably in the range of 8 or more and 12 or less. Particularly suitable layer structures include "0-4-8", "0-6-12", and "0-4-12". The layer structure "0-4-12" is particularly preferred.

[0042] As described above, the conductor 1 according to this embodiment has a low number of wires 3 constituting the inner layer so as to achieve a wire ratio of 2.0 or greater, thereby achieving high flexibility. The flexibility of the conductor 1 can be evaluated, for example, by the repulsive force generated when the conductor 1 is bent. The smaller the repulsive force generated when the conductor 1 is bent at a predetermined bending radius, the higher the flexibility of the conductor 1. For example, the repulsive force of the conductor 1 according to the embodiment of the present disclosure (the conductor of interest) is preferably smaller than the repulsive force of a reference conductor obtained by flattening a raw stranded wire 9′, in which the child strands 8 are closely packed, as shown in FIG. 2B . It is even more preferable for the repulsive force of the conductor of interest to be 99% or less, more preferably 95% or less, 90% or less, or 85% or less of the repulsive force of the reference conductor. Here, the reference conductor may be made of the same material as the conductor of interest, and may be obtained by flattening a raw stranded wire having the same conductor cross-sectional area and a close-packed structure, into a flat shape with the same flattening ratio as the conductor of interest. Alternatively, the repulsive force may be measured using insulated wires in which the reference conductor and the target conductor are coated with insulating coatings of the same material and thickness, and the two may be compared. Since insulating coatings usually have higher flexibility than the wire conductors, the contribution of the insulating coating can be ignored when comparing repulsive forces.

[0043] In the electric wire conductor 1 according to this embodiment, the improvement in flexibility achieved by increasing the strand ratio is achieved by both ensuring ease of relative movement of the strands 3 and suppressing hardening of the strands 3, as described above. The degree of hardening of the strands 3 is reflected in the conductor resistance of the electric wire conductor 1. In copper and copper alloys, as well as aluminum and aluminum alloys, work hardening often increases the conductor resistance. Therefore, it can be evaluated that the higher the conductor resistance, the greater the degree of hardening of the strands 3 in the electric wire conductor 1 due to the application of a load. Preferably, the increase in conductor resistance compared to the raw stranded wire 9 is kept to 22% or less, and even 18% or less. Furthermore, it is preferable that the conductor resistance of the electric wire conductor 1 is smaller than the conductor resistance of the reference conductor. [Example]

[0044] Examples are shown below. However, the present invention is not limited to these examples. Here, the relationship between strand ratio and flexibility was investigated for insulated wires having flat conductors. In the following, sample preparation and evaluation were performed at room temperature in the atmosphere.

[0045] (Sample preparation) First, the electric wire conductors constituting Samples A1 to A5 and Samples B1 to B5 were prepared. First, a plurality of aluminum alloy wires were twisted together to form a child strand, and then a plurality of the same child strands were twisted together to obtain a raw stranded wire with a substantially circular cross section. The raw stranded wire was rolled into a flat shape using a roller to prepare a flat electric wire conductor. The layer structure of the arrangement of the child strands differed depending on the sample, as shown in Tables 1 and 2. In each sample, the layer structure of the electric wire conductor after flattening was the same as that of the raw stranded wire. In all samples, the conductor cross-sectional area in the raw stranded wire state was 62.0±0.6 mm 2 The outer diameter of the wire was set according to the number of wires (number of child strands) so that the wires were uniform. The flattening ratio of the electric conductor was controlled by the magnitude of the force applied to the raw stranded wire from the roller, and was set to 5 for Samples A1 to A5 and 6 for Samples B1 to B5.

[0046] An insulating coating was formed on the outer periphery of each of the electric conductors prepared above to produce an insulated electric wire. The insulating coating was made of polyolefin, and a coating layer with a thickness of 0.6 mm was formed by extrusion molding.

[0047] (Evaluation of the condition of electric wire conductors) For each sample of electric wire conductor, we confirmed whether the child strand structure was maintained and whether the layer configuration established by the arrangement of the child strands in the raw stranded wire was maintained even after flattening. Specifically, at the end of the flattened electric wire conductor, the twist structure was unwound in units of child strands, and the distribution of the child strands was observed. This observation confirmed that the child strand structure and the predetermined layer configuration established in the raw stranded wire were maintained in the electric wire conductor after flattening, forming outer and inner layers.

[0048] Furthermore, each sample of insulated wire was embedded in acrylic resin and cut perpendicular to the axial direction to prepare cross-sectional samples. Observation of these cross-sectional samples confirmed that the wire conductor was formed into a flat shape with the specified flatness ratio. The cross-sectional area of ​​the conductor was also calculated from the conductor weight.

[0049] (Measurement of repulsive force) Each sample insulated wire was cut to a length of 400 mm, and both ends were held with a gripper to bend the insulated wire. The bending radius (R) was set to 40 mm, and the load applied to the end of the insulated wire was measured with a load cell attached to the gripper while the wire was bent to 135°. 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 using a resistance meter.

[0051] (Evaluation results) First, we present the results of confirming the structure and distribution of the child strands by untwisting the strands at the end of the conductor for representative samples A2 and A5. Based on the layer structure of the raw strand, a "1-6-12" layer structure was set for sample A2, and a "0-4-12" layer structure was set for sample A5. Photographs of these samples taken after untwisting the child strands are shown in Figures 3A to 3D. Figures 3A and 3B are of sample A2, and Figures 3C and 3D are of sample A5. Figures 3A and 3C show the state after untwisting the outer layer, while Figures 3B and 3D show the state after removing all of the outer layers and untwisting the inner layer.

[0052] These photographs reveal multiple groups of strands corresponding to the child strands in both Samples A2 and A5, demonstrating that the structure of the child strand, consisting of multiple strands twisted together, is clearly maintained even after flattening. Furthermore, the arrangement of these child strands maintains a clear division into an outer layer (O) and an inner layer (I). In particular, the inner layer of Sample A2, shown in Figure 3B, features a two-layer structure, the inner layer (I), distinguishing between a single child strand (II) constituting the innermost layer and the other child strands arranged around it. This distribution of the child strands confirms that the flattened conductor maintains the specified layer structure established in the raw strand. In other words, the "1-6-12" layer structure is maintained in Sample A2 after flattening, while the "0-4-12" layer structure is maintained in Sample A5. Similarly, for the other samples, it was confirmed that the child strand structure and the layer structure established in the raw strand are retained in the flattened conductor.

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

[0054] Figures 4A to 4D show cross-sectional photographs of Samples A2, A5, B2, and B5. Each cross-sectional photograph confirms that the conductor is flattened to a predetermined flatness ratio. In each conductor, the wires in the inner region are significantly deformed compared to the outer periphery, particularly the widthwise opposite regions. However, the degree of deformation of the wires in the inner region is smaller in Sample A5 than in Sample A2, and in Sample B5 than in Sample B2, and gaps are maintained between the wires in the inner region. The wire ratio of the conductor is 1.71 (12 / 7) for Samples A2 and B2, and 3 (12 / 4) for Samples A5 and B5. In other words, the above-mentioned trend confirmed in the cross-sectional photographs indicates that increasing the wire ratio and reducing the number of wires in the inner layer relative to the outer layer reduces wire deformation and densification in the inner layer. Similar trends were also confirmed for samples other than Samples A2, A5, B2, and B5. In addition, in the cross-sectional samples, the structure and distribution of the child strands in the wire conductor are difficult to see due to the operations of embedding in acrylic resin and cutting. As shown in Figures 3A to 3D, the structure and distribution of the child strands, which were confirmed when the twisted structure of the wire conductor was unwound, cannot be clearly recognized in the cross-sectional photographs.

[0055] Tables 1 and 2 show the layer configurations, strand ratios, and evaluation results for samples A1 to A5 with an aspect ratio of 5 and samples B1 to B5 with an aspect ratio of 6, respectively. The rate of change in conductor cross-sectional area from the raw stranded wire is also shown in parentheses. Figures 5A and 5B also show the relationship between strand ratio and repulsive force for samples A1 to A5 and samples B1 to B5, respectively. Approximation lines are also shown in the figures. The sample number is also written near each plot point.

[0056] [Table 1]

[0057] [Table 2]

[0058] Tables 1 and 2 and Figures 5A and 5B show that, regardless of the flattening ratio, the larger the strand ratio, the lower the repulsive force and the higher the flexibility. This can be interpreted as a result of the fact that, as explained above based on the cross-sectional photographs in Figures 4A to 4D, the higher the strand ratio and the fewer the number of inner layer strands relative to the number of outer layer strands, which reduces the densification and deformation of the inner layer strands. In other words, when the densification and deformation of the inner layer strands are reduced, the strands are more likely to move relative to each other and the constituent materials are less likely to harden, resulting in high flexibility of the wire conductor. By setting the strand ratio to 2.0 or higher, as in Samples A3 to A5 and B3 to B5, the repulsive force can be reduced compared to the wire conductor with the layer structure "1-6-12" (Samples A2 and B2), which is formed from a raw wire with a conventional, close-packed base strand. In particular, the repulsive force is significantly reduced in Samples A5 and B5, which have a strand ratio of 3.

[0059] The conductor resistance measurement results in Tables 1 and 2 show that, in general, the larger the strand ratio, the lower the conductor resistance. The magnitude of the conductor resistance is an indicator of the load applied to the conductor during flattening and the resulting hardening of the strands; low conductor resistance indicates a low load and a low degree of hardening of the strands. In other words, in areas with a high strand ratio, the hardening of the strands is reduced, which, combined with the effect of the ease of relative movement of the strands, contributes to improved flexibility. The conductor resistance of the raw stranded wire was 0.43 mΩ / m. In all samples, the conductor resistance of the wire conductor after flattening increased from the raw stranded wire state, but the increase was kept small in samples with a high strand ratio.

[0060] Finally, comparing the evaluation results for a flatness ratio of 5 (samples A1 to A5) and a flatness ratio of 6 (samples B1 to B5), we see that a larger load is applied to the conductor during flattening when the flatness ratio is 6, which is reflected in a larger reduction in the conductor cross-sectional area and higher conductor resistance. However, when the flatness ratio is 6, there is a more pronounced tendency for conductor resistance to be kept low when the strand ratio is increased. Meanwhile, the effect of reducing the repulsive force by increasing the strand ratio is achieved to the same extent for all flatness ratios. In particular, samples A5 and B5, which have a strand ratio of 3, measured repulsive forces that were similarly small.

[0061] 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]

[0062] 1. Electrical Wire Conductor 2-ply twisted wire 2i inner layer stranded wire 2o outer layer stranded wire 3 wire 8-stranded wire 8i Raw material inner layer stranded wire 8o raw material outer layer twisted wire 9 Raw material stranded wire 9' Raw stranded wire (conventional form) h height w width

Claims

1. The wire is configured as a stranded wire including a plurality of child strands each formed by twisting together a plurality of wires, a cross section of the stranded wire intersecting the axial direction 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, the total number of the wires constituting the outer layer child wire arranged on the outer periphery of the flat portion is defined as the number of outer layer wires, and the total number of the wires constituting the inner layer child wire arranged inside the outer layer child wire is defined as the number of inner layer wires, A conductor, wherein a ratio of the number of the outer layer strands to the number of the inner layer strands is 3.0 or more and 3.5 or less.

2. the number of wires constituting each of the plurality of child strands is the same, 2. The conductor according to claim 1, wherein a ratio of the number of the outer layer stranded wires to the number of the inner layer stranded wires is 3.0 or more and 3.5 or less.

3. The conductor according to claim 1 , wherein the inner layer stranded wire is provided in a single layer around the outer layer stranded wire.

4. The conductor according to claim 1 , wherein the dimension in the width direction of the cross section of the conductor is five times or more the dimension in the height direction.

5. Conductor cross-sectional area is 16 mm ２ The conductor according to claim 1 .

6. At least a part of the wire has a cross-sectional shape that is deformed from a circular shape, The conductor according to claim 1 , wherein a deformation rate of the wire from a circular shape is smaller at an outer periphery of the cross section of the conductor than at an inner portion thereof.

7. The conductor according to any one of claims 1 to 6, an insulating coating covering the outer periphery of the wire conductor.

8. A wire harness comprising the insulated wire according to claim 7.

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