Insulated Wire and Wire Harnesses

Abstract

To provide an insulated wire in which a cross-section of a conductor is a flat shape and which is excellent in bending selectivity in a height direction of a flat shape, and a wire harness provided with such insulated wire.SOLUTION: An insulated wire 1 having a conductor 10 and an insulating coating 20 covering an outer periphery of the conductor 10. The conductor 10 in the insulated wire 1 has a flat portion having a cross section perpendicular to an axial direction in a flat shape having a dimension in a width direction larger than a dimension in a height direction. In the flat portion, the bending rigidity of the insulated wire 1 in a width direction x is 2.6 times or more the bending rigidity in a height direction y. Moreover, a wire harness contains the insulated wire 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

[0003] In conventional flat cables, rectangular conductors are often used as the conductor, as disclosed in Patent Documents 1 and 2. A rectangular conductor is a metal wire formed into a rectangular cross section. In addition, Patent Documents 3 and 4, filed by the applicants, disclose an electric wire conductor in which a stranded wire made by twisting together multiple strands is formed into a flat shape from the viewpoint of achieving both flexibility and space saving. [Prior art documents] [Patent documents]

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

[0005] When an electric wire having a flat conductor is routed in a specified space such as inside an automobile, the bend can be easily performed by bending the electric wire in the height direction (flat direction) of the flat shape in the route path, the load applied to the electric wire is small, and the space-saving effect of the flat shape can be effectively utilized for the route. However, depending on the specific configuration of the electric wire, the electric wire may be bent not only in the height direction of the flat shape but also in the width direction (edge ​​direction). When the electric wire is designed and the route path is set on the assumption that the electric wire will be bent in the height direction of the flat shape for routeing, if the electric wire is bent in the width direction, this hinders the routeing work and makes it difficult to route the electric wire in the specified path. If the electric wire can be selectively bent in the height direction, the routeability of the electric wire can be improved.

[0006] Therefore, an object of the present invention is to provide an insulated electric wire having a conductor with a flat cross section and excellent selectivity for bending the flat shape in the height direction, and a wire harness including such an insulated electric wire. [Means for solving the problem]

[0007] The insulated wire of the present disclosure has a conductor and an insulating coating that covers an outer periphery of the conductor, wherein the conductor has a flat portion in a cross section perpendicular to an axial direction, the flat portion having a width dimension greater than a height dimension, and the bending rigidity of the insulated wire in the width direction at the flat portion is 2.6 times or more greater than the bending rigidity in the height direction.

[0008] The wire harness of the present disclosure includes the insulated wire. Effect of the Invention

[0009] The insulated electric wire and wire harness according to the present disclosure are an insulated electric wire in which the cross section of the conductor is flattened, and which has excellent selectivity for bending the flattened shape in the height direction, and a wire harness including such an insulated electric wire. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an insulated wire according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a side view illustrating a method for measuring bending rigidity. [Diagram 3] FIG. 3 is a diagram showing the relationship between deflection and bending load obtained in measuring bending stiffness. [Figure 4] FIG. 4 is a side view illustrating a method for measuring bending stress. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. The insulated wire according to the present disclosure is an insulated wire having a conductor and an insulating coating that covers the outer periphery of the conductor, wherein the conductor has a flat portion in a cross section perpendicular to the axial direction, the flat portion having a width dimension greater than a height dimension, and the bending rigidity of the insulated wire in the width direction at the flat portion is 2.6 times or more greater than the bending rigidity in the height direction.

[0012] In the insulated wire, the bending rigidity in the width direction of the flat shape is 2.6 times or more greater than the bending rigidity in the height direction, so bending in the width direction is less likely to occur compared to bending in the height direction. In other words, the selectivity of bending in the height direction is high. Therefore, when routing the insulated wire, it is easy to perform the task of routing the wire by bending it in the height direction while avoiding unintended bending in the width direction.

[0013] Here, the conductor may be a stranded wire made of a plurality of strands. This increases the bending flexibility of the conductor, making it easier to arrange the insulated wire by bending the conductor in the height direction of the flat shape. Compared to a case where the conductor is made of a single wire, the flexibility in the width direction of the flat shape is also higher. However, by setting the bending rigidity in the width direction to be 2.6 times or more the bending rigidity in the height direction as described above, it is possible to sufficiently suppress the occurrence of unintended bending in the width direction.

[0014] In this case, the cross section of the conductor may have a width dimension that is 3.0 times or more the height dimension, which increases the flatness of the flat shape of the conductor and effectively increases the ratio of the widthwise bending rigidity to the heightwise bending rigidity of the insulated wire.

[0015] The outer diameter of the strands is preferably 0.32 mm or less. When the strands constituting the stranded wire are thin, the conductor becomes flexible overall. This makes it easier to bend the insulated wire in the height direction of the flat shape. On the other hand, the ease of bending is not improved in the width direction as much as in the height direction due to the influence of friction between the strands. This makes it easier to increase the selectivity of bending the insulated wire in the height direction.

[0016] In addition, the conductor cross-sectional area is 100 mm 2 Although it may be difficult to route an insulated electric wire having a large conductor cross-sectional area while bending it flexibly, the insulated electric wire of the present disclosure can be easily routed by taking advantage of the ease of selective bending in the height direction of the flat shape.

[0017] The bending stiffness in the width direction is 0.5 N·m 2 This can effectively prevent the insulated wire from being unintentionally bent in the width direction.

[0018] The bending stiffness in the height direction is 0.3 N m 2 In this case, bending of the insulated electric wire in the height direction can be effectively promoted.

[0019] The conductor may be made of aluminum or an aluminum alloy. Since aluminum and aluminum alloys have lower electrical conductivity than copper and copper alloys, insulated wires are often designed with a large conductor cross-sectional area. However, the insulated wire of the present disclosure can be easily routed even when the conductor cross-sectional area is large by utilizing the selective bending ease in the height direction of the flat shape.

[0020] A wire harness according to the present disclosure includes the insulated electric wire. By including the insulated electric wire, the wire harness has excellent selectivity for bending the flat shape of the conductor in the height direction. Therefore, when the insulated electric wire is routed in a predetermined space in the form of a wire harness, it is easy to route the insulated electric wire in the height direction while suppressing the influence of bending in the width direction.

[0021] [Details of the embodiment of the present disclosure] In the following, an insulated wire and a wire harness according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this specification, the concepts of linear, parallel, vertical, and the like, which indicate the shape and arrangement of each part of the insulating coating, include errors from the geometric concepts within the range permitted for this type of insulated wire, such as deviations of approximately ±15% in length and approximately ±15° in angle. In this specification, the cross section of a conductor or an insulated wire refers to a cross section cut perpendicular to the axial direction (longitudinal direction), unless otherwise specified. In addition, the various characteristics are values ​​evaluated at room temperature in the atmosphere.

[0022] <Outline of insulated wire> 1 shows a cross-sectional view of an insulated wire 1 according to one embodiment of the present disclosure. The insulated wire 1 according to this embodiment has a conductor 10 and an insulating coating 20. The insulating coating 20 covers the entire outer periphery of the conductor 10.

[0023] The conductor 10 may have a single wire structure made of a continuous metal material such as a metal foil or a metal plate, or may be configured as a stranded wire in which a plurality of wires 15 are twisted together. In the illustrated embodiment, the conductor 10 is configured as a stranded wire.

[0024] The conductor 10 has a flat outer shape at least in a part along the axial direction. In other words, the conductor 10 has a flat portion in which the cross section perpendicular to the axial direction is flat. In this embodiment, the entire axial area of ​​the conductor 10 has such a flat portion. Here, the cross section of the conductor 10 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 that constitute 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 straight line and includes the entire cross section.

[0025] The cross section of the conductor 10 may have any specific shape as long as it has a flat shape, but in this embodiment, the cross section of the conductor 10 is approximated to a rectangle. Here, the cross section of the conductor 10 being rectangular means that the circumscribing figure of the conductor 10 shown by the dashed line in the figure can be approximated to a rectangle with an error range of about ±15° in terms of the relationship between each side. Examples of flat shapes other than a rectangle include an ellipse, an oval, an oval (a shape with semicircles on both ends of a rectangle), a parallelogram, a trapezoid, etc.

[0026] When the conductor 10 is configured as a stranded wire, the conductor 10 can be formed, for example, by rolling a raw stranded wire in which a plurality of elemental wires 15 are stranded together into a substantially circular cross section. The cross-sectional shape of at least a part of each of the elemental wires 15 constituting the conductor 10 may be deformed from a circular shape due to forming into a flat shape. However, from the viewpoint of ensuring high flexibility in the conductor 10, it is preferable that the deformation rate of the elemental wires 15 from a circular shape is smaller in the outer periphery of the cross section of the conductor 10 than in the inner part. In addition, it is preferable that a gap capable of accommodating one or more elemental wires 15 is left between each of the elemental wires 15 in the cross section of the conductor 10.

[0027] The insulated electric wire 1 according to the present embodiment has a conductor 10 with a flat cross section, and therefore the space required for wiring can be made smaller than that of an electric wire having a conductor with a substantially circular cross section with the same conductor cross-sectional area. In other words, the space around a certain electric wire in which other electric wires or other components cannot be arranged can be made smaller. In particular, the space occupied by the electric wire along the height direction (y direction) can be made smaller, and space saving can be easily achieved. In addition, since the conductor 10 has a flat shape and the dimension in the height direction is small, the insulated electric wire 1 exhibits high flexibility in the height direction. In particular, when the conductor 10 is made of a stranded wire, the conductor 10 is made as an assembly of a plurality of thin-diameter element wires 15, and thus a particularly high flexibility can be obtained. Thus, the insulated electric wire 1 according to the present embodiment achieves both high space saving and flexibility due to the conductor 10 having a flat shape.

[0028] The material constituting the conductor 10 is not particularly limited, and various metal materials can be applied. Representative metal materials constituting the conductor 10 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 large in order to ensure the necessary electrical conductivity. Therefore, flattening the conductor 10 has a large effect on space saving and bending flexibility in the height direction. From this viewpoint, it is preferable to construct the conductor 10 from aluminum or an aluminum alloy. From the same viewpoint, it is preferable to make the conductor 10 from a material having a cross-sectional area of ​​100 mm 2 More than 120mm 2 Although there is no particular upper limit on the conductor cross-sectional area, it is preferable to set it to, for example, 300 mm 2 It is best to keep it below this.

[0029] The material constituting the insulating coating 20 is not particularly limited as long as it is an insulating material, but it is preferable that the base material is an organic polymer. Examples of the organic polymer include olefin-based polymers such as polyolefin 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 20 may contain various additives such as a flame retardant in addition to the organic polymer.

[0030] Since the insulating coating 20 has a considerably higher flexibility than the conductor 10, the degree of flexibility of the insulated wire 1 as a whole is determined almost entirely by the degree of flexibility of the conductor 10. However, if the insulating coating 20 also has a high flexibility, it is easier to increase the flexibility of the insulated wire 1 as a whole. From this perspective, it is preferable that the flexural modulus of elasticity of the material constituting the insulating coating 20 is 30 MPa or less, and more preferably 20 MPa or less.

[0031] The insulated electric wire 1 according to the present embodiment may be used alone or as a constituent member of the wire harness according to the embodiment of the present disclosure. The wire harness according to the embodiment of the present disclosure includes the insulated electric wire 1 according to the above embodiment. The wire harness may include a plurality of the insulated electric wires 1, or may include other types of insulated electric wires in addition to the insulated electric wire 1. Preferably, the insulated electric wires 1 are arranged in a width direction (x direction) and / or a height direction (y direction). In this case, the specific arrangement structure of the insulated electric wires 1 is not particularly limited, but a preferred embodiment may include a form in which the insulated electric wires 1 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 insulated electric wires 1 are uniform.

[0032] <Details of the insulated wire configuration> The structure and characteristics of the insulated wire 1 will be described in detail below. In the following, the description will be made mainly assuming that the conductor 10 is configured as a twisted wire of aluminum or an aluminum alloy. However, as described above, in the insulated wire 1 according to the embodiment of the present disclosure, the conductor 10 may be in the form of either a twisted wire or a solid wire, and the type of metal material constituting the conductor 10 is not particularly limited, and each of the configurations described below applies regardless of the form and metal type of the conductor 10. The specific upper and lower limit values ​​of each parameter may differ depending on whether the conductor 10 is a twisted wire or a solid wire and the metal type, but the relationship between the magnitude of the value of each parameter and the phenomenon that occurs or the effect obtained does not depend on the form and metal type of the conductor 10.

[0033] In the insulated wire 1 according to the present embodiment, the conductor 10 has a flat shape, so that the bending rigidity in the width direction (edge ​​direction; x direction) is greater than the bending rigidity in the height direction (flat direction; y direction). In particular, regarding the bending rigidity of the insulated wire 1, it is preferable that the bending rigidity ratio, defined as the ratio of the bending rigidity in the width direction to the bending rigidity in the height direction, is 2.6 or more as shown in the following formula (1). In other words, it is preferable that the bending rigidity in the width direction is 2.6 times or more the bending rigidity in the height direction. [Bending stiffness ratio] = [Bending stiffness in width direction] / [Bending stiffness in height direction] (1)

[0034] The bending rigidity of the insulated wire 1 can be evaluated, for example, by a three-point bending test in accordance with JIS K 7171. That is, as shown in Fig. 2, the insulated wire 1 is supported with two cylinders T1, T1 as fulcrums, and a cylinder T2 is pressed into the midpoint between the cylinders T1, T1 from the direction opposite to the supporting direction, thereby applying a bending load F to the insulated wire 1. At this time, the amount of pressing of the cylinder T2 is the deflection of the insulated wire 1. Based on the measurement results, the bending rigidity can be calculated by the following formula (2). [Bending stiffness] = ([Bending load F] x [Support distance L] 3 ) / (48×[deflection]) (2) The above three-point bending test is performed on bending the flattened shape of the insulated wire 1 in the height direction and width direction. In other words, measurements are taken with the height direction and width direction of the insulated wire 1 facing the load application direction, which corresponds to the vertical direction in Figure 2. Then, the bending rigidity ratio can be calculated using the above formula (1).

[0035] In the insulated electric wire 1, the bending stiffness ratio is 2.6 or more, so that the insulated electric wire 1 can be easily bent flexibly in the height direction, but is difficult to bend in the width direction. That is, the insulated electric wire 1 has excellent selectivity for bending in the height direction. As a result, when the insulated electric wire 1 is routed, it can be routed in a predetermined path by utilizing bending in the height direction while suppressing unintended bending in the width direction. In the insulated electric wire 1, since the conductor 10 has a flat shape, bending in the height direction, which is a smaller dimension, generates a smaller load on the conductor 10 and the insulating coating 20 due to bending than bending in the width direction, which is a larger dimension. In addition, the insulated electric wire 1 has a high space-saving property in the height direction due to the flat shape of the conductor 10, and by routing the wire while bending it in the height direction, the space-saving property can be effectively utilized in the route. From the viewpoint of further enhancing these effects, it is more preferable that the bending stiffness ratio of the insulated electric wire 1 is 3.0 or more, and more preferably 3.5 or more. Although there is no particular upper limit set for the bending stiffness ratio, it is advisable to set it to approximately 20.0 or less from the viewpoint of avoiding excessive restrictions on bending in the width direction.

[0036] The bending rigidity ratio of the insulated wire 1 as a whole is dominated by the bending rigidity of the conductor 10. Therefore, the bending rigidity ratio of the insulated wire 1 can be adjusted by the specific configuration of the conductor 10, such as the diameter of the stranded wires 15 and the flattening ratio of the conductor 10. As will be described later, the bending rigidity ratio can be increased as the diameter of the stranded wires 15 is smaller and the flattening ratio is larger. The insulating coating 20 does not completely affect the bending rigidity of the insulated wire 1 in each direction, but its contribution is limited compared to that of the wire conductor 10.

[0037] In the insulated electric wire 1, the magnitude of the bending rigidity in the height direction and the bending rigidity in the width direction are not particularly limited as long as the bending rigidity ratio is 2.6 or more. However, the greater the bending rigidity in the width direction and the smaller the bending rigidity in the height direction, the easier it is to increase the bending rigidity ratio and improve the selectivity of bending in the height direction. For example, when the bending rigidity in the width direction is 0.3 N·m 2 or more, even 0.5N·m 2 More than 0.8N m 2 If the bending stiffness in the height direction is 0.3 N m or more, bending of the insulated electric wire 1 in the width direction can be effectively suppressed. 2 Less than or even 0.25N m 2 If it is less than this, bending of the insulated wire 1 in the height direction can be effectively promoted.

[0038] In the insulated electric wire 1, the aspect ratio of the conductor 10, i.e., the ratio of the width to the height of the conductor 10 (w / h), is preferably 2.0 or more. If the aspect ratio of the cross-sectional shape of the insulated electric wire 1 is large, the area occupied by the conductor 10 in the width direction becomes larger compared to the height direction, making it difficult to bend the conductor 10 in the width direction. In other words, the bending rigidity ratio of the insulated electric wire 1 becomes large, making it easier to increase the selectivity of bending in the height direction. It is particularly preferable that the aspect ratio of the conductor 10 is 3.0 or more. There is no particular upper limit to the aspect ratio of the conductor 10, but it may be set to, for example, 6.0 or less from the viewpoint of avoiding excessive flattening.

[0039] When the conductor 10 is configured as a stranded wire, the outer diameter of the stranded wire 15 is preferably 0.40 mm or less. When the conductor cross-sectional area is the same, the thinner the stranded wire 15, the higher the overall flexibility of the conductor 10. The effect of improving flexibility due to the thinning of the stranded wire 15 is well reflected in bending in the height direction of the flat shape, making bending easier. However, since the number of strands 15 gathered in the width direction of the flat shape increases, the total sum of frictional forces acting between the strands 15 when bending increases. Therefore, even if the strands 15 are thinned, the effect of improving flexibility in the width direction is not so great. Therefore, by thinning the strands 15, the flexibility in the height direction of the flat shape is preferentially improved, and the bending rigidity ratio increases. The outer diameter of the strands 15 is preferably 0.32 mm or less, and more preferably 0.30 mm or less. There is no particular lower limit to the outer diameter of the strands 15, but from the viewpoint of maintaining the strength of the strands 15, it is preferable that the outer diameter be 0.1 mm or more, for example.

[0040] As described above, the higher the bending stiffness ratio of the insulated electric wire 1, the higher the selectivity of bending in the height direction. The selectivity of bending can be evaluated, for example, by the bending stress when bending the insulated electric wire 1. It can be said that the higher the bending stress when bending the insulated electric wire 1 in the width direction is, the higher the selectivity of bending in the height direction is. As shown in the examples described later, if the bending stiffness ratio is set to 2.6 or more, when the insulated electric wire 1 is held at two points 200 mm apart and bent to 60° with a bending radius (r) of 150 mm, the bending stress ratio, which is the ratio of the stress when bending in the width direction to the stress when bending in the height direction, for the stress generated at the held parts, is set to 4.0 or more (the bending stress ratio is defined as the ratio of the stress when bending in the height direction to the stress when bending in the width direction (the following formula (3)). [Bending stress ratio] = [Bending stress in width direction] / [Bending stress in height direction] (3)

[0041] A bending stress ratio of 4.0 or more means that bending the insulated wire 1 in the width direction requires four times the force required to bend it in the height direction, and it becomes significantly less likely that the insulated wire 1 will be unintentionally bent in the width direction when force is applied to bend the insulated wire 1 in the height direction. In the insulated wire 1, if parameters such as the flattening ratio and the diameter of the strands 15 are set according to the specific shape and metal type of the conductor 10 so that the bending stress ratio is 4.0 or more, the selectivity for bending in the height direction can be sufficiently increased. It is more preferable if the bending stress ratio is 4.5 or more, or 5.0 or more. EXAMPLES

[0042] Examples are shown below. Note that the present invention is not limited to these examples. Here, the relationship between the bending stiffness ratio of an insulated wire having a flat conductor and the selectivity of bending in the height direction was investigated. In the following, the preparation of samples and each evaluation were performed at room temperature in the atmosphere.

[0043] (Sample Preparation) First, a conductor made of a stranded wire was prepared using an aluminum alloy strand. For samples A1 to A8, the outer diameter and conductor configuration of the strand used were as shown in Table 1. The conductor configuration is expressed in the format of "number of parent strands / number of child strands / strand diameter (mm)". The obtained stranded wire was rolled into a flat shape using a roller to prepare a conductor. At this time, the rolling ratio was changed to set the aspect ratio w / h as shown in Table 1. In addition, single-wire conductors were also prepared using an aluminum alloy as samples B1 to B5.

[0044] The outer circumference of each conductor was coated with an insulating coating having a thickness of 1.6 mm by extrusion molding. The following two types of coating materials were used: Coating material 1 - organic polymer: silane cross-linked polyethylene (100 parts by mass), additive: magnesium hydroxide (70 parts by mass), flexural modulus: 35 MPa Coating material 2 - organic polymer: silane cross-linked polyethylene (100 parts by mass), additives: bromine-based flame retardant (30 parts by mass) and antimony trioxide (10 parts by mass), flexural modulus: 15 MPa

[0045] (Evaluation of bending stiffness) For each of the insulated electric wires obtained above, the bending stiffness in the width direction and the height direction was measured by a three-point bending test conforming to JIS K 7171. That is, as shown in FIG. 2, the insulated electric wire 1 was supported by two cylinders T1, T1 as supports, and the cylinder T2 was pressed into the middle point between the cylinders T1, T1 from the opposite direction to the support direction, and a bending load F was applied to the insulated electric wire 1. The relationship with the deflection of the insulated electric wire 1, which is indicated as the amount of pressing of the cylinder T2, was recorded. The distance L between the supports was 100 mm, and the length of the insulated electric wire 1 used as the sample was 150 mm. The cylinders T1, T2 used to support the insulated electric wire 1 and apply the bending load had a diameter of 5 mm. The pressing speed when applying the bending load F was 100 mm / min.

[0046] Measurements were performed on bending the flattened shape in the height direction and in the width direction. The measurements provide the relationship between deflection and bending load, as shown in FIG. 3. The measurement results for areas with small deflection were approximated by the above formula (2) to obtain the bending rigidity in each direction. The obtained values ​​were then used to calculate the bending rigidity ratio, as shown in formula (1), which is the ratio of the bending rigidity in the width direction to the bending rigidity in the height direction. Note that FIG. 3 shows the measurement results when sample A1 in Table 1 was bent in the width direction.

[0047] (Evaluation of bending stress) The bending stress of each of the insulated electric wires having a conductor made of a stranded wire was measured by the method illustrated in FIG. 4. In the measurement, each insulated electric wire 1 was cut to a length of 200 mm, and both ends were held by gripping tools T3 and T3, respectively, to bend the insulated electric wire 1. In a state where the insulated electric wire 1 was bent to 60° at a predetermined bending radius (r), a load F' applied to the end of the insulated electric wire 1 was measured by a load cell attached to the gripping tool. Then, the component of the load F' perpendicular to the axial direction of the insulated electric wire 1 was obtained and defined as the bending stress f. The bending radius (r) was set to three values: 150 mm, 100 mm, and 50 mm. The bending stress was measured for each of bending in the height direction and bending in the width direction of the flattened shape. Then, as shown in the above formula (3), the bending stress ratio was calculated as the ratio of the bending stress in the width direction to the bending stress in the height direction.

[0048] (result) Table 1 shows the configuration of the insulated wire and the evaluation results for Samples A1 to A8, whose conductors were made of twisted wires.

[0049] [Table 1]

[0050] In Table 1, the bending stiffness ratio of the insulated electric wire and the bending stress ratio at r=150 mm are shown in bold. Comparing them, it is found that the bending stiffness ratio at r=150 mm is generally larger as the bending stiffness ratio is larger. In other words, it is found that the bending selectivity in the height direction of the flat shape is higher as the bending stiffness ratio is larger. Furthermore, in all of the samples A1 to A6, which have a bending stiffness ratio of 2.6 or more, the bending stress ratio is 4.0 or more. In other words, the force required to bend the insulated electric wire in the width direction is 4.0 times or more the force required to bend the insulated electric wire in the height direction, and the bending selectivity in the height direction is significantly higher. On the other hand, in the samples A7 and A8, the bending stiffness ratio is less than 2.6. And the bending stress ratio is less than 4.0, and the bending selectivity in the height direction is low. From the above results, it is found that the bending stiffness ratio is a good indicator of the bending direction selectivity in an insulated electric wire having a flat conductor. By setting the bending stiffness ratio to 2.6 or more, the insulated wire can be made to have high selectivity for bending in the height direction.

[0051] Samples A1, A5, A7, and A8 differ in the aspect ratio of the conductor. In ascending order of aspect ratio, samples A5, A1, A8, and A7 are the largest. In descending order of bending stiffness ratio, samples A5, A1, A8, and A7 are the largest, and the relationship between the aspect ratio and the size is consistent. This shows that by increasing the aspect ratio of the conductor, the bending stiffness ratio of the insulating coating can be increased, and the selectivity of bending in the height direction can be improved.

[0052] Samples A1, A2, and A6 differ in the wire diameter. The largest wire diameter is sample A6, followed by sample A1 and sample A2. The largest bending stiffness ratio is sample A2, followed by sample A1 and sample A6, with the relationship between the wire diameter and the magnitude being reversed. This shows that by reducing the outer diameter of the wires that make up the conductor, the bending stiffness ratio of the insulating coating can be increased, improving the selectivity of bending in the height direction.

[0053] The pair of samples A1 and A3, and the pair of samples A2 and A4, differ in the type of coating material. In both pairs, the values ​​of bending rigidity in the width direction and height direction are greater when a coating material 1 with a high elastic modulus is used (samples A1 and A2) than when a coating material 2 with a low elastic modulus is used (samples A3 and A4). However, the difference in bending rigidity ratio due to the difference in the type of coating material is small. In particular, the pair of samples A1 and A3 has the same bending rigidity ratio value regardless of the type of coating material. It can be said that the influence of the type of insulating coating on the bending rigidity ratio of insulated electric wires is limited, and the influence of the conductor configuration is dominant.

[0054] As described above, the bending stress ratio at a large bending radius of r=150mm shows a good correlation with the bending rigidity ratio, and the bending stress ratio tends to increase as the bending rigidity ratio increases. In the cases of r=100mm and 50mm, a similar tendency is observed that the bending stress ratio increases as the bending rigidity ratio increases, but the correlation between the bending rigidity ratio and the bending stress ratio is lower than in the case of r=150mm. For example, when comparing sample A1 and sample A2, the bending rigidity ratio is larger in sample A2, and the bending stress ratio at r=150mm is also larger in sample A2, but the bending stress ratio at r=100mm and 50mm is larger in sample A1, and the relationship is reversed. When the bending radius is small, a large force is required to bend in the width direction, but a certain amount of force is also required to bend in the height direction. Therefore, when the bending rigidity ratio is large, that is, even if there is a large difference in the bending rigidity between the width direction and the height direction, it is interpreted that the difference in the force required for bending, i.e., the bending stress, due to the bending direction is small. In addition, in the installation of an insulated electric wire, unintended bending in the width direction is likely to occur when the bending radius is large, which requires less bending force. As described above, since the bending stiffness ratio of an insulated electric wire shows a high correlation with the bending stress ratio at a large bending radius such as r = 150 mm, it can be said that the bending stiffness ratio can be used as a good indicator for avoiding unintended bending in the width direction, especially when performing gentle bending with a large bending radius.

[0055] Finally, Table 2 shows the evaluation results of the wire configuration and bending rigidity for Samples B1 to B5, in which the conductor has a single wire structure.

[0056] [Table 2]

[0057] According to Table 2, even when the conductor is formed as a single wire, the bending stiffness ratio can be made 2.6 or more by making the conductor flat, as in the case of the stranded wire, as in the case of samples B2 to B5. Furthermore, as the flatness ratio increases from sample B2 to sample B5, the bending stiffness ratio also increases accordingly.

[0058] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0059] 1. Insulated wire 10 Conductors 15 Wire F Bending load in evaluation of bending elasticity F' Load measured in bending stress evaluation f bending stress L Distance between supports r bending radius T1,T2 Cylinder T3 gripper x width direction y Height direction

Claims

1. A conductor; An insulated wire having an insulating coating that covers an outer periphery of the conductor, the conductor has a flat portion having a flat shape in a cross section perpendicular to an axial direction, the flat portion having a width dimension greater than a height dimension, In the flat portion, the bending rigidity of the insulated wire in the width direction is 3.0 times or more larger than the bending rigidity in the height direction, The conductor is configured as a stranded wire in which a plurality of wires having an outer diameter of 0.30 mm or less are stranded together, An insulated wire having a conductor cross-sectional area of ​​100 mm 2 or more.

2. 2. The insulated wire according to claim 1, wherein the cross section of the conductor has a dimension in the width direction that is 3.0 times or more larger than a dimension in the height direction.

3. The bending stiffness in the width direction is 0.5 N·m ２ The insulated wire according to claim 1 or 2.

4. The bending stiffness in the height direction is 0.3 N·m ２ The insulated wire according to claim 1 , wherein the tensile strength is less than 1 / 2 mm.

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

6. A wire harness comprising the insulated wire according to any one of claims 1 to 5.

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