Wire conductor, insulated wire, and wire harness

Abstract

Provided is an electric wire conductor that shapes a stranded wire obtained by stranding wire materials into a flat shape, can suppress an increase in electric resistance caused by a reduction in lay length to be small, and provided is an insulated electric wire and a wire harness that have such an electric wire conductor. An electric wire conductor (1) is a stranded wire that has: a lower stranding layer (10) obtained by stranding a plurality of sub-stranded wires (2) obtained by stranding a plurality of wire materials (3) into a wire harness; and an upper stranding layer (20) obtained by twisting a plurality of the sub-stranded wires (2) to adhere to the outer periphery of the lower stranding layer (10), a cross section of the electric wire conductor (1) orthogonal to the axial direction of the stranded wire has a flat portion, the flat portion is a flat shape in which the width direction dimension (w) is greater than the height direction dimension (h), and in the flat portion, the lay length of the wire materials (3) in the sub-stranded wires (2) is a (mm), the lay length of the sub-stranded wires (2) in the lower stranding layer (10) is b (mm), the lay length of the sub-stranded wires (2) in the upper stranding layer (20) is c (mm), and (0.2a + b + 0.5) / c ≤ 1 is satisfied.

Description

Technical Field

[0001] This disclosure relates to wire conductors, insulated wires, and wire harnesses. Background Technology

[0002] Flat cables are commonly known to be made using wire conductors with a flat shape. By using flat cables, compared to using conventional wires with wire conductors having a roughly circular cross-section, the space occupied during installation can be reduced.

[0003] In conventional flat cables, as disclosed in Patent Documents 1 and 2, flat conductors are frequently used as wire conductors. A flat conductor is a structure in which a single metal wire is shaped into a quadrilateral cross-section. Furthermore, Patent Documents 3-5 disclosed by the applicant disclose a wire conductor in which, from the viewpoint of achieving both flexibility and space-saving, a stranded wire composed of multiple strands is shaped into a flat shape. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication 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. 2022-058941 Summary of the Invention The problem that the invention aims to solve

[0005] As disclosed in Patent Documents 3-5, space-saving can be achieved while maintaining flexibility by using wire conductors with stranded wires shaped into a flat shape. However, with the increasing use of wire conductors with large conductor cross-sectional areas due to the demand for high current, it is difficult to ensure sufficient flexibility for installation in wire conductors composed of stranded wires shaped into a flat shape if the conductor cross-sectional area becomes larger. In wire conductors with large conductor cross-sectional areas, reducing the strand pitch is sometimes used as a method to improve flexibility. However, when the strand pitch is reduced in a wire conductor, the actual length of the wire constituting a certain length of wire conductor becomes longer, thereby increasing the conductor resistance of the wire conductor. In addition, when a wire conductor with a reduced strand pitch is shaped into a flat shape, the wire is formed in a high-density filling state, and the forming process causes significant deformation of the wire. As a result, the conductor resistance is prone to increase due to processing curing, reduction of cross-sectional area, etc. Thus, when the strand pitch of a flat-shaped wire is reduced to improve its flexibility, the conductor resistance may increase due to two main reasons: the actual length of the wire increases and the wire deforms. Consequently, the conductor cross-sectional area required to ensure the desired conductivity becomes larger, thus hindering space-saving design of the wire conductor.

[0006] Therefore, the problem is to provide an electrical conductor in which the stranded wire formed by twisting wires is shaped into a flat shape, which can suppress the increase in resistance caused by reducing the twist pitch. In addition, the problem is to provide insulated wires and wire harnesses having such an electrical conductor. Solution for solving the problem

[0007] The wire conductor disclosed herein is configured as a stranded wire, the stranded wire having: a lower stranded layer, obtained by forming a bundle of multiple sub-stranded wires and twisting them together, the sub-stranded wires being obtained by twisting multiple wires together; and an upper stranded layer, obtained by twisting and attaching multiple of the sub-stranded wires to the outer periphery of the lower stranded layer, the cross-section of the wire conductor orthogonal to the axial direction of the stranded wire having a flat portion, the flat portion being a flat shape with a width dimension greater than a height dimension, in the flat portion, the strand pitch of the wires in the sub-stranded wires is set to a (mm), the strand pitch of the sub-stranded wires in the lower stranded layer is set to b (mm), and the strand pitch of the sub-stranded wires in the upper stranded layer is set to c (mm), satisfying (0.2a+b+0.5) / c≤1.

[0008] The insulated wire of this disclosure has the wire conductor and an insulating covering portion that encloses the outer periphery of the wire conductor. The wire harness of this disclosure includes the insulated wire. Invention Effects

[0009] The wire conductor disclosed herein is a wire conductor formed by shaping stranded wires into a flat shape, which can minimize the increase in resistance caused by reducing the strand pitch. Furthermore, the insulated wires and wire harnesses of this disclosure possess such a wire conductor. Attached Figure Description

[0010] Figure 1 This is a schematic cross-sectional view illustrating an embodiment of the wire conductor of this disclosure. In the main view, the individual wires constituting the sub-stranded wire are omitted from the display; the cross-section of the sub-stranded wire including the wires is illustrated in the enlarged view enclosed by a quadrilateral. Figure 2A This is a graph showing the relationship between the differences (c-b) between the sub-pitch a, the lower pitch b, and the upper pitch c. Data points with a resistance rise rate less than 10% are shown in black, while data points with a resistance rise rate greater than 10% are shown in hollow graphs. Figure 2B The relationship between (0.2a+b+0.5) / c and the rate of increase in resistance is shown. Detailed Implementation

[0011] (Description of embodiments of this disclosure) First, embodiments of this disclosure will be described. (1) The wire conductor of this disclosure is configured as a stranded wire, the stranded wire having: a lower stranded layer, which is obtained by forming a bundle of multiple sub-stranded wires and twisting them together, the sub-stranded wires being obtained by twisting multiple wires together; and an upper stranded layer, which is obtained by twisting and attaching multiple sub-stranded wires to the outer periphery of the lower stranded layer, the cross section of the wire conductor orthogonal to the axial direction of the stranded wires having a flat portion, the flat portion being a flat shape with a width dimension greater than a height dimension, in the flat portion, the strand pitch of the wires in the sub-stranded wires is set to a (mm), the strand pitch of the sub-stranded wires in the lower stranded layer is set to b (mm), and the strand pitch of the sub-stranded wires in the upper stranded layer is set to c (mm), satisfying (0.2a+b+0.5) / c≤1.

[0012] In the flat portion of the aforementioned wire conductor, the three strand pitches—a, b, and c—have a relationship: (0.2a + b + 0.5) / c ≤ 1. As shown in the following embodiments, this relationship is determined to be a range that sufficiently suppresses the increase in resistance associated with the flattening of the wire conductor. This is illustrated below: if the strand pitch c in the upper layer is sufficiently large compared to the strand pitch b in the lower layer and the strand pitch a in the sub-strands, especially compared to the lower pitch b, then the increase in conductor resistance caused by the deformation of the wire as the wire conductor is formed into a flat shape is minimized. Furthermore, by increasing the strand pitch c of the upper layer through which the sub-strands pass on the outermost side of the wire conductor, the actual length of the wire constituting the wire conductor is shortened, thereby also achieving the effect of suppressing conductor resistance. In other words, by setting the three strand pitches a, b, and c to satisfy the above-mentioned relationship, from the viewpoint of suppressing wire deformation associated with the flattening of the wire conductor and shortening the actual length of the wire constituting the wire conductor, the conductor resistance in a flat-shaped wire conductor can be reduced to a low level. When increasing the conductor cross-sectional area, and when it is desirable to set the strand pitches a, b, and c as small as possible to improve the flexibility of the wire conductor, if each strand pitch is set to satisfy the above-mentioned relationship, then both high flexibility and reduced conductor resistance can be achieved in the wire conductor.

[0013] (2) In the manner described in (1) above, it is preferable that, in the cross-section, at least a portion of the wire constituting the wire conductor is deformed from a circular shape. The deformation of the wire indicates that the flat-shaped wire conductor is formed by rolling a raw material conductor with a roughly circular cross-section. However, even if the wire is deformed by rolling, the increase in conductor resistance accompanying the wire deformation can be minimized by selecting the strand pitches a, b, and c in a manner that satisfies the above-described relationship.

[0014] (3) In the manner described in (1) or (2) above, it is preferable that the wire conductor is manufactured by rolling a raw material conductor composed of stranded wire with a circular cross-section, and the rate of increase in conductor resistance of the flat portion based on the raw material conductor is suppressed to less than 10%. In the insulated wire of the embodiments of this disclosure, by satisfying the relationship (0.2a+b+0.5) / c≤1 for the three strand pitches a, b, and c, the deformation of the wire accompanying the rolling process can be minimized. As a result, the increase in conductor resistance due to the processing and curing of the wire, the reduction of cross-sectional area, etc., can be minimized. In fact, as shown in the following embodiments, by satisfying the above relationship, the rate of increase in conductor resistance caused by rolling can be suppressed to less than 10%. Thus, compared with the state before the flat shape, the conductor resistance of the flat-shaped wire conductor does not increase excessively, and a high degree of space saving and flexibility can be obtained. The conductor of an electrical wire is manufactured by rolling a raw conductor, which is indicated by the deformation of the cross-sectional shape of each strand and at least a portion of each wire constituting the conductor from a circle. Furthermore, this is further indicated by the fact that the rate of deformation from a circle in the strands and wires is smaller in the upper strands than in the lower strands.

[0015] (4) In any of the methods described in (1) to (3) above, it is preferable that the flatness ratio, which represents the ratio of the width dimension of the flat portion to the height dimension, is 3 or more. The greater the flatness ratio, the more easily the conductor resistance of the wire conductor increases due to the deformation of the wire when formed into a flat shape. However, in the insulated wire of the embodiments of this disclosure, by satisfying the relationship (0.2a+b+0.5) / c≤1 for the three strand pitches a, b, and c, even when the wire conductor is formed into a flat shape with a flatness ratio of 3 or more, the deformation of the wire during forming can be minimized. As a result, the increase in conductor resistance due to wire processing and curing, reduction in cross-sectional area, etc., can be minimized. By increasing the flatness ratio of the wire conductor, the space-saving performance of the wire conductor is improved.

[0016] (5) In any of the methods described in (1) to (4) above, it is preferred that the conductor cross-sectional area of ​​the wire conductor is 16 mm². 2 In the above-mentioned case, the strand pitch 'a' of the wires in the sub-stranded wires is 10 mm or more, and the strand pitch 'c' of the sub-stranded wires in the upper stranded layer is 70 mm or more. The conductor cross-sectional area is 16 mm². 2 In the above cases, by increasing the sub-pitch a and the top pitch c as described above, it is easier to suppress the rise in conductor resistance to a small extent.

[0017] (6) In any of the embodiments (1) to (5) above, it is preferred that the wire is made of aluminum or an aluminum alloy. Due to the influence of the oxide film on the surface of the wire, it is difficult for the wires in the wire conductor to conduct. Therefore, when the actual length of the wire constituting the conductor increases, the overall conductor resistance of the wire conductor tends to increase. However, in the wire conductor of the embodiments of this disclosure, by setting the strand pitches a, b, and c to satisfy the relationship (0.2a+b+0.5) / c≤1, the increase in conductor resistance can be effectively suppressed.

[0018] (7) The insulated wire of this disclosure has: a wire conductor of any one of (1) to (6) above; and an insulating covering portion covering the outer periphery of the wire conductor. The insulated wire includes the wire conductor of the above, which can suppress the rise in resistance by satisfying a predetermined relationship through three strand pitches a, b, and c. Therefore, as a characteristic of the insulated wire, the rise in resistance in the wire conductor can be suppressed.

[0019] (8) The wire harness disclosed herein includes the insulated wire described in (7) above. As a whole, the wire harness also has the effect of suppressing the increase of resistance in the wire conductor.

[0020] (Details of the embodiments disclosed herein) Hereinafter, the wire conductor, insulated wire, and wire harness according to embodiments of the present disclosure will be described in detail with the aid of accompanying drawings. In this specification, the concepts of straight line, parallel, perpendicular, circular, circumferential, etc., representing the shape or arrangement of components, include deviations of approximately ±15% in length and approximately ±15° in angle, which are errors arising from geometric concepts within the permissible range in such wire conductors. In this specification, unless otherwise stated, the cross-section of a wire conductor refers to a cross-section perpendicular to the axial direction (long side direction).

[0021] <The composition of wire conductors, insulated wires, and wire harnesses> exist Figure 1 The diagram schematically shows a cross-sectional view of an electrical conductor 1 according to an embodiment of the present disclosure. The electrical conductor 1 is configured as a stranded wire, which includes multiple wires 3, formed by twisting these multiple wires 3 together.

[0022] The wire conductor 1 has a flat shape in at least a portion of the region along the axial direction. That is, it has a flat portion in at least a portion of the region along the axial direction, and the cross-section of the flat portion orthogonal to the axial direction of the wire conductor 1 is flat. In this embodiment, the entire region along the axial direction of the wire conductor 1 is processed into such a flat portion shape. Here, the flat shape of the cross-section of the wire conductor 1 means that the width w of the longest straight line that runs parallel to the edge of the cross-section and covers the entire cross-section is greater than the height h of the straight line orthogonal to that straight line and covers the entire cross-section.

[0023] As long as the cross-section of the wire conductor 1 has a flat shape, it can be any specific shape. Examples of flat shapes include rectangles, ellipses, oblong shapes, Japanese coin shapes (rectangles with semicircles at both ends), parallelograms, trapezoids, etc. If the circumscribed figure of the cross-section can approximate these shapes, then the cross-sectional shape of the wire conductor 1 can be considered as such. Among the listed shapes, any one of rectangles, ellipses, oblong shapes, and Japanese coin shapes is preferred. Figure 1 In the manner shown, the wire conductor 1 has a cross-sectional shape that approximates the shape of a Japanese gold coin.

[0024] In the wire conductor 1, not all the wires 3 are twisted together; instead, the wires 3 are divided into multiple strands 2 to form the wire conductor 1. Furthermore, these multiple strands 2 constitute two types of mother strands: a lower strand 10 and an upper strand 20. That is, the strands 2 are formed by twisting multiple wires 3 together. The lower strand 10 is formed as a structure obtained by forming and twisting the multiple strands 2 into a bundle. Further, an upper strand 20 is formed on the outer periphery of the lower strand 10. The upper strand 20 is coaxially configured with the lower strand 10, formed by twisting and attaching multiple strands 2 to the outer periphery of the lower strand 10. Figure 1 In the main diagram, the cross-section of each sub-stranded wire 2 is simplified by solid circles (sub-stranded wires 2 constituting the upper stranded layer 20) and dashed circles (sub-stranded wires 2 constituting the lower stranded layer 10). In the enlarged diagram enclosed by quadrilaterals, the structure of sub-stranded wires 2 including multiple wires 3 is illustrated.

[0025] In the wire conductor 1 of this embodiment, as described in detail below, the strand pitch a of the wire 3 in the sub-stranded wire 2, the strand pitch b of the sub-stranded wire 2 in the lower stranded layer 10, and the strand pitch c of the sub-stranded wire 2 in the upper stranded layer 20 are set to satisfy a predetermined relationship. By ensuring that those strand pitches a, b, and c satisfy the predetermined relationship, the increase in conductor resistance in the wire conductor 1, which is mainly caused by the increase in the actual length of the wire 3 constituting the wire conductor 1 and the increase in resistance due to the deformation of the wire 3 during flattening, can be suppressed.

[0026] The wire conductor 1 can be formed by rolling a raw material conductor consisting of stranded wires with a roughly circular cross-section. As the raw material conductor, it is sufficient to simply strand multiple stranded wires 3 with roughly circular cross-sections 3 together to form sub-stranded wires 2 with roughly circular cross-sections, and then use these sub-stranded wires 2 to form a lower strand 10 and an upper strand 20, thus constituting a conductor wire with a roughly circular cross-section. As the raw material conductor is formed into a flat shape, the cross-sectional shape of at least a portion of each sub-stranded wire 2 and at least a portion of each wire 3 constituting the wire conductor 1 can also be deformed from a circular shape. The rate of deformation of the sub-stranded wires 2 and wires 3 from a circular shape is generally smaller in the outer periphery of the cross-section of the wire conductor 1, i.e., the upper strand 20, than in the inner periphery, i.e., the lower strand 10. In particular, the rate of deformation of the sub-stranded wires 2 and wires 3 is easily suppressed to a small extent in the region at both ends and near the width direction of the outer periphery.

[0027] The wire with conductor 1 in this embodiment has a flat cross-section, which reduces the space required for installation compared to a wire with a roughly circular cross-section having the same conductor cross-sectional area. That is, it reduces the space around a wire where other wires or components cannot be placed. In particular, it reduces the space occupied by the wire along its height, facilitating space saving. Furthermore, because conductor 1 is composed of stranded wire obtained by twisting multiple wires 3 together, it has high flexibility. Conductor 1 exhibits particularly high flexibility in the height direction. Thus, by having conductor 1 composed of stranded wire and having a flat shape, the wire achieves both high space saving and flexibility. Insulated wires and wire harnesses including conductor 1, due to their high space saving and flexibility, are particularly suitable for installation in narrow spaces or complex paths, such as inside automobiles.

[0028] From the viewpoint of improving space-saving efficiency, particularly in the height direction, and from the viewpoint of enhancing the effect of suppressing the increase in conductor resistance caused by flattening through the relationship of the three strand pitches a, b, and c as described later, it is preferable that the width w in the cross-section of the wire conductor 1 is at least three times the height h. That is, it is preferable that the aspect ratio (w / h) is 3 or more. It is even more preferable that the aspect ratio is 5 or more. There is no particular upper limit set for the aspect ratio of the wire conductor 1, but from the viewpoint of avoiding excessive load on the wire conductor 1 due to its flattened shape, it is preferable to suppress it to about 10 or less.

[0029] There is no specific limitation on the cross-sectional area of ​​the conductor 1, but a larger cross-sectional area results in a greater effect on flattening the conductor 1 and improving space-saving. Furthermore, from the viewpoint of ensuring flexibility, a larger conductor cross-sectional area makes it easier to set a smaller strand pitch. However, as described later, by maintaining a predetermined relationship between strand pitches a, b, and c, the increase in conductor resistance caused by reducing the strand pitch can be suppressed. From these viewpoints, for example, it is preferable to set the conductor cross-sectional area to 2 mm². 2That's all. There is no specific upper limit set for the conductor cross-sectional area, but from the viewpoint of easily ensuring flexibility, it is preferable to limit it to, for example, 200 mm². 2 the following.

[0030] The material of the wire 3 constituting the conductor 1 is not particularly limited, and various metal materials can be used. Representative metal materials constituting the wire 3 include copper and copper alloys (copper-based metals), and aluminum and aluminum alloys (aluminum-based metals). In particular, aluminum-based metals have lower conductivity than copper-based metals, so in order to ensure the necessary conductivity, the conductor cross-sectional area is usually set to be large. As mentioned above, the larger the conductor cross-sectional area, the greater the effect of flattening the conductor 1 and setting the strand pitches a, b, and c to satisfy the predetermined relationship. Furthermore, the wire 3 made of aluminum-based metals has an oxide film on its surface, making it difficult to achieve conductivity between the wires in the conductor 1. Therefore, when the path of the wire 3 constituting the outer periphery of the conductor 1 becomes longer, the overall conductor resistance of the conductor 1 tends to increase due to the influence of these outer periphery wires 3. For these main reasons, the conductor resistance tends to increase in conductor conductors using wires made of aluminum alloys. However, by setting the twist pitches a, b, and c to satisfy a predetermined relationship, the increase in conductor resistance caused by these main factors can be effectively suppressed.

[0031] The outer diameter of the wire 3 constituting the conductor 1 is not specifically limited, but can be exemplified as 0.18 mm or more and 2 mm or less. The number of wires 3 constituting one stranded wire 2 is also not specifically limited, and can be exemplified as 2 or more and 230 or less. In this embodiment, each stranded wire 2 constituting the lower strand 10 and the upper strand 20 has the same configuration. That is, the material, outer diameter, number of wires, and strand pitch (c) of the wire 3 constituting the stranded wire 2 are the same among all the stranded wires 2 included in the conductor 1. The specific number of stranded wires 2 constituting the lower strand 10 and the upper strand 20 is not specifically limited, but for the lower strand 10, can be exemplified as 2 or more and 7 or less, and for the upper strand 20, can be exemplified as 6 or more and 12 or less.

[0032] An embodiment of the insulated wire disclosed herein includes a wire conductor 1 and an insulating covering portion (not shown). The insulating covering portion completely covers the outer periphery of the wire conductor 1. The material constituting the insulating covering portion is not specifically limited as long as it is an insulating material, but an organic polymer is preferred as the base material. Examples of organic polymers include olefin polymers such as polyolefins and olefin copolymers, halogen polymers such as polyvinyl chloride, various elastomers, and rubber. The organic polymer can be cross-linked and can also be foamed. Furthermore, in addition to the organic polymer, the insulating covering portion may also contain various additives such as flame retardants. The insulating covering portion is preferably formed as an extruded body.

[0033] The insulated wires of the embodiments of this disclosure can be used either alone or as constituent components of the wire harnesses of the embodiments of this disclosure. The wire harnesses of the embodiments of this disclosure include the insulated wires of the embodiments of this disclosure. The wire harness may include multiple insulated wires of the embodiments of this disclosure; additionally, it may include other types of insulated wires besides those of the embodiments of this disclosure. Preferably, multiple insulated wires of the embodiments of this disclosure are arranged in the width direction and / or height direction. In this case, the specific arrangement structure of the multiple insulated wires is not particularly limited, but as a suitable approach, it can be exemplified that multiple insulated wires are arranged in the width direction and fixed to a common sheet by welding or the like. In this case, it is particularly preferable that the multiple insulated wires arranged have the same height. The uses of the insulated wires and wire harnesses of the embodiments of this disclosure are not particularly limited, but they are particularly suitable as wiring materials in automobiles where wiring to be laid in a confined space is required.

[0034] <Twist Pitch in Wire Conductors> The wire conductor 1 of the present disclosure has a structure in which multiple wires 3 are twisted together to form sub-strands 2, and multiple sub-strands 2 are further used to form a lower strand 10 and an upper strand 20, so it has the following three strand pitches. Sub-pitch: Set as the pitch a (mm) of the wire 3 in sub-twisted wire 2. Bottom twist pitch: Set as the twist pitch b (mm) of the sub-twisted wire 2 in the bottom twist layer 10. Top twist pitch: Set as the twist pitch c (mm) of the sub-twisted wire 2 in the top twist layer 20.

[0035] In the wire conductor 1 of the embodiments of this disclosure, the above three strand pitches a, b, and c satisfy the following formula (1). (0.2a+b+0.5) / c≤1 (1) By setting the three twist pitches a, b, and c to satisfy equation (1), the resistance rise in a flat wire conductor 1 can be minimized. The reason is as follows.

[0036] As shown in the following embodiments, by setting the three strand pitches to satisfy Equation (1), the increase in conductor resistance due to the deformation of the wire 3 during flattening can be minimized when the raw conductor is shaped into a flat shape to obtain the wire conductor 1. Equation (1) means that if the upper strand pitch c is sufficiently large compared with the lower strand pitch b and the sub-stretch pitch a, especially the lower strand pitch b, then the increase in conductor resistance due to flattening in the wire conductor 1 is minimized. That is, the rate of increase in conductor resistance due to flattening, based on the conductor resistance of the raw conductor, can be minimized.

[0037] Here, equation (1) can also be written as equation (1') below. c﹣b≥0.2a+0.5 (1') Equation (1') indicates that the upper strand pitch c should be set to have a sufficiently large difference relative to the lower strand pitch b. If the difference between the upper strand pitch c and the lower strand pitch b is small, when the raw conductor is formed into a flat shape by rolling or the like to obtain the wire conductor 1, the wire 3 constituting the lower strand 10 is bound by the upper strand 20, making it prone to being subjected to a large load during forming. In addition, the lower strand 10 also undergoes deformation such as pushing the upper strand 20 upward, making it difficult to stably form and maintain the flat shape of the wire conductor 1. In contrast, if there is a sufficient difference between the upper strand pitch c and the lower strand pitch b, the sub-strands 2 constituting the upper strand 20 are easy to move when forming into a flat shape, and it is also difficult to cause forced load application or deformation in the lower strand 10 due to the binding from the upper strand 20. As a result, the deformation of the wire 3 accompanying the flattening is suppressed to a small extent. As a result, the flat shape of the wire conductor 1 can be stably formed and maintained, and the resistance increase caused by the processing and solidification accompanying the deformation of the wire 3, the reduction of cross-sectional area, etc., can be suppressed to a small extent. In fact, Equation (1') was determined in the embodiments to be the range that can sufficiently suppress the resistance increase.

[0038] In equation (1), increasing the top strand pitch c is the most effective way to reduce the value on the left side to easily satisfy equation (1). That is, even if the sub-stretch pitch a or the bottom strand pitch b is relatively large, equation (1) can still be satisfied as long as the top strand pitch c is large enough. Increasing the top strand pitch c means that when the wire conductor 1 is formed by flattening the raw material conductor, the top strand layer 20 constituting the outer periphery of the wire conductor 1 can move with a higher degree of freedom. Thus, by utilizing the movement of the top strand layer 20, the load applied along with flattening and the deformation of the wire 3, as well as the resulting increase in resistance, can be easily suppressed on the wire conductor 1 as a whole. In addition, in the top strand layer 20, the sub-stretched wires 2 pass through the outermost periphery of the wire conductor 1 to form a stranded structure, so the length of the sub-stretched wires 2 constituting the top strand layer 20 and the actual length of the wire 3 constituting these sub-stretched wires 2 can easily become longer. Therefore, by increasing the upper twist pitch c compared to the lower twist pitch a and the lower twist pitch b, the actual length of the wire 3 constituting the upper twist layer 20 is reduced, thereby achieving a greater reduction in the conductor resistance of the wire conductor 1.

[0039] By setting the sub-pitch a, lower pitch b, and upper pitch c to satisfy the relationship of equation (1), from the perspectives of both suppressing the resistance increase associated with the deformation of the wire 3 when it is formed into a flat shape and suppressing the actual length of the wire 3 constituting the wire conductor 1, the conductor resistance in the wire conductor 1 with a flat shape can be reduced to a small value. In fact, as confirmed in the embodiment, by satisfying equation (1), the rate of increase in conductor resistance associated with flattening can be suppressed to less than 10%. The rate of increase in conductor resistance is preferably less than 8%, and further less than 7%. Here, the rate of increase in conductor resistance can be set based on the conductor resistance of the raw material conductor or the reference conductor. The reference conductor refers to a wire whose constituent material and outer diameter, the number of wires constituting the sub-strands, and the number of sub-strands constituting the lower and upper strands are consistent with the wire conductor 1, the cross-sectional shape of the wire is circular, and in the cross-section orthogonal to the axial direction, the center of each sub-strand constituting the upper strand exists on the circumference (i.e., the cross-sectional shape of the reference conductor as a whole is approximately circular). Regarding the strand pitches a, b, and c, it is sufficient to make the strand pitch in the reference conductor 1 10 mm larger than that in wire conductor 1. The reference conductor itself is a hypothetical conductor wire, but it corresponds to the raw material conductor actually used as the raw material in manufacturing wire conductor 1 through flattening. Regarding the flat portion of wire conductor 1 and the raw material conductor or reference conductor, it is sufficient to measure the conductor resistance in a section of the same length, and evaluate the rate of increase of the conductor resistance (R1) in the flat portion using the conductor resistance (R0) of the raw material conductor or reference conductor as a reference ((R1﹣R0) / R0×100%). It should be noted that in the reference conductor, making the strand pitches a, b, and c 10 mm larger than those in wire conductor 1 reflects the situation where the strand pitch decreases as the raw material conductor is rolled. The amount of change in strand pitches a, b, and c during actual rolling is less than 10 mm.

[0040] As shown in equation (1), if the value of (0.2a+b+0.5) / c is 1 or less (1.0 or less), the resistance rise of the wire conductor 1 can be suppressed to a sufficiently small value. However, if the value is set to 0.8 or less, or even 0.7 or less, it is even easier to suppress the resistance rise of the wire conductor 1 to a small value. On the other hand, the value of (0.2a+b+0.5) / c does not have a particularly set lower limit and can be set to a small value within a range that is not limited by manufacturing equipment or materials. It is preferable to set it to approximately 0.1 or more.

[0041] As long as the relationship in equation (1) is satisfied, the ranges of the three strand pitches a, b, and c are not specifically specified. They can be appropriately selected based on parameters such as the outer diameter of wire 3 and the cross-sectional area of ​​conductor 1, within a range not constrained by manufacturing equipment or materials. For example, when the conductor cross-sectional area is 16mm²... 2In the above case, it is only necessary to set the sub-strand pitch a to 10 mm or more, the upper strand pitch c to 70 mm or more, and set the three strand pitches a, b, and c such that Formula (1) is satisfied. By setting the sub-strand pitch a and the upper strand pitch c sufficiently large as described above, even when the cross-sectional area of the conductor is increased, the increase in conductor resistance caused by the two main factors, namely the increase in the actual length of the wire rods 1 constituting the wire conductor 3 and the deformation of the wire rods 3 accompanying the formation into a flat shape, can be easily suppressed to a low level. In particular, by increasing the upper strand pitch c to 70 mm or more, Formula (1) can be satisfied even when the lower strand pitch b is relatively large to a certain extent, and the increase in conductor resistance can be suppressed to a low level. In addition, regarding the magnitude relationship among the three strand pitches a, b, and c, it is sufficient that a < b < c. Examples

[0042] Examples are shown below. It should be noted that the present invention is not limited to these Examples. Here, in a flat-shaped conductor, the influence of the relationship among the three strand pitches on the increase in conductor resistance is investigated. The preparation and evaluation of test samples are carried out at room temperature in the atmosphere.

[0043] (Preparation of Test Samples) First, a raw material conductor is produced. Specifically, a plurality of aluminum alloy wire rods each having an outer diameter of 0.3 mm are stranded to form a sub-stranded wire. The sub-stranded wires are bundled and stranded to form a lower stranded layer. Further, sub-stranded wires are arranged on the outer periphery of the lower stranded layer, and are twisted and attached coaxially with the lower stranded layer to form an upper stranded layer, thereby obtaining a raw material conductor having a substantially circular cross section. As shown in Table 2 later, a plurality of test samples are produced as raw material conductors with different conductor cross-sectional areas, sub-strand pitch a, lower strand pitch b, and upper strand pitch c. The conductor cross-sectional area is varied by changing the number of wire rods constituting the sub-stranded wires and the number of sub-stranded wires constituting the lower stranded layer and the upper stranded layer. Specifically, each parameter is set as shown in Table 1 below. The conductor cross-sectional area is represented by a nominal cross-sectional area. It should be noted that when the number of sub-stranded wires constituting the lower stranded layer is 7, 6 sub-stranded wires are twisted around 1 central sub-stranded wire to form the lower stranded layer. (Table 1)

[0044] Each raw material conductor of the test samples obtained above is rolled by a pair of rolls to be flattened, thereby producing a flat wire conductor. The flatness ratio of the wire conductor is controlled by the magnitude of the force applied to the raw material conductor by the pair of rolls. It should be noted that the strand pitches a, b, and c are reduced by the flattening, but the variation amount of each of these strand pitches is 10 mm or less.

[0045] (Evaluation of Conductor Resistance Increase Rate) For each sample's wire conductor, the conductor resistance was measured in both the raw conductor state before and after flattening. Furthermore, using the conductor resistance before flattening (R0) as a reference, the rate of increase in the conductor resistance after flattening (R1) was calculated ((R1﹣R0) / R0×100%). The conductor resistance was measured using a ohmmeter and the four-terminal method over a 1m interval in both the raw and flattened wire conductors.

[0046] (Evaluation Results) Table 2 shows the evaluation results of the conductor resistance increase rate associated with flattening for each fabricated sample, along with the conductor cross-sectional area and aspect ratio, sub-pitch a, bottom pitch b, and top pitch c. The calculated values ​​of c-b and (0.2a+b+0.5) / c are also shown in the table.

[0047] (Table 2)

[0048] exist Figure 2A The diagram above, based on the data in Table 2, shows the relationship between the sub-pitch a, the difference c-b between the upper and lower pitches. In the figure, data points with a conductor resistance increase rate less than 10% are indicated by shaded graphics, while data points with a conductor resistance increase rate greater than 10% are indicated by hollow graphics. Additionally, as shown in the example, data points are represented using different graphics for each conductor cross-sectional area.

[0049] according to Figure 2A In the upper region of the graph (where c-b is large), data points with a conductor resistance increase rate of less than 10% are represented by blacked-out graphics. In the lower region of the graph (where c-b is small), data points with a conductor resistance increase rate of less than 10% are represented by hollow graphics. As shown by the dashed line in the graph, a boundary is established to divide these two types of data points. This boundary line can be expressed by the formula c-b = 0.2a + 0.5. In the region above this line (where c-b ≥ 0.2a + 0.5), the conductor resistance increase rate is suppressed to less than 10%.

[0050] In the above Figure 2A In the equation representing the region where the rate of increase in conductor resistance is suppressed to less than 10%, we get c﹣b≥0.2a+0.5. However, if we rearrange it, it becomes (0.2a+b+0.5) / c≤1. Table 2 shows the value of (0.2a+b+0.5) / c equivalent to the left side of this equation. Furthermore, in... Figure 2B The relationship between the value of (0.2a+b+0.5) / c and the measured value of the rate of increase in conductor resistance is shown.

[0051] according to Figure 2BIt can be roughly observed that the rate of increase in conductor resistance increases with the increase of (0.2a+b+0.5) / c. Furthermore, in the region where (0.2a+b+0.5) / c ≤ 1.0, it can be confirmed that the rate of increase in conductor resistance is less than 10%. Based on this result, it can be said that by setting the sub-pitch a, bottom pitch b, and top pitch c to sufficiently small values, such as (0.2a+b+0.5) / c being less than 1.0, the increase in conductor resistance associated with flattening can be suppressed to a small extent.

[0052] The embodiments of this disclosure have been described in detail above. However, the present invention is not limited to the above embodiments and various changes can be made without departing from the spirit of the present invention. Explanation of reference numerals in the attached figures

[0053] 1. Wire conductor 2 stranded wires 3. Wire 10 Lower strand 20 Upper strand h is the height of the wire conductor. w is the width of the wire conductor.

Claims

1. An electrical conductor configured as a stranded wire, said stranded wire having: The lower strand is obtained by forming and twisting multiple sub-strands into a bundle, wherein the sub-strands are obtained by twisting multiple wires together; and The upper strand is obtained by twisting and attaching multiple of the aforementioned sub-stranded wires to the outer periphery of the lower strand. The cross-section of the wire conductor orthogonal to the axis of the stranded wire has a flat portion, wherein the flat portion is a flat shape in which the dimension in the width direction is greater than the dimension in the height direction. In the flat section, the strand pitch of the wire in the sub-stranded wire is set to a (mm), the strand pitch of the sub-stranded wire in the lower stranded layer is set to b (mm), and the strand pitch of the sub-stranded wire in the upper stranded layer is set to c (mm). The condition (0.2a+b+0.5) / c≤1 is satisfied.

2. The wire conductor according to claim 1, wherein, In the cross-section, at least a portion of the wire constituting the wire conductor is deformed from a circular shape.

3. The wire conductor according to claim 1, wherein, The wire conductor is manufactured by rolling a raw material conductor consisting of stranded wire with a circular cross-section. The rate of increase in conductor resistance of the flat portion, based on the raw material conductor, is suppressed to less than 10%.

4. The wire conductor according to claim 1, wherein, The flatness ratio, which indicates that the dimension of the flat portion in the width direction is relative to the dimension in the height direction, is 3 or more.

5. The wire conductor according to claim 1, wherein, The conductor cross-sectional area of ​​the wire is 16 mm². 2 above, The strand pitch 'a' of the wires in the sub-stranded wire is 10 mm or more. The twist pitch c of the sub-strands in the upper strand layer is 70mm or more.

6. The wire conductor according to claim 1, wherein, The wire is made of aluminum or an aluminum alloy.

7. An insulated wire, comprising: The wire conductor according to any one of claims 1 to 6; and The insulating covering portion covers the outer periphery of the wire conductor.

8. A wire harness comprising the insulated wire of claim 7.

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