Flat electric wire

Abstract

A flat electric wire (1) includes a plurality of conductor portions (10) arranged in parallel and in contact with each other, and an insulator (20) configured to cover the plurality of conductor portions (10) together. The plurality of conductor parts (10) includes a stranded wire (11) in which wires (11a) made of a first metal are stranded, and a single wire (12) made of a second metal that is plastically deformed more easily than the first metal. The conductor size of the single wire (12) is set such that the resistance of the single wire is equal to or less than the resistance of the stranded wire (11). The stranded wires (11) and the single wires (12) are symmetrically arranged in the width direction.

Description

Technical Field

[0001] The present invention relates to a flat electric wire. Background Art

[0002] In the related art, a flat electric wire in which a conductor is covered with an insulator so that the entire electric wire has a flat shape has been proposed. Such flat electric wires include a flat electric wire in which the conductor is composed of a busbar (for example, see Patent Document 1), and a flat electric wire in which a plurality of strands formed by twisting a plurality of wires are arranged in parallel to form a conductor (for example, see Patent Document 2).

[0003] Citation List

[0004] Patent Literature

[0005] Patent Document 1: JP2020-053377A

[0006] Patent Document 2: JP2021-157968A Summary of the invention

[0007] Regarding the flat electric wire described in Patent Document 1, since the conductor is formed of a busbar, the flat electric wire has excellent shape retention performance, but poor flexibility. On the other hand, regarding the flat electric wire described in Patent Document 2, since the conductor is formed of a plurality of twisted wires, the flat electric wire has excellent flexibility, but poor shape retention performance. Therefore, in the prior art, the flat electric wire described in Patent Document 1 is used where shape retention is required, and the flat wire described in Patent Document 2 is used where flexibility is required. Therefore, a flat electric wire that achieves both shape retention and flexibility is required.

[0008] The present invention is proposed to solve these problems in the prior art, and an object of the present invention is to provide a flat electric wire capable of achieving both shape retention and flexibility.

[0009] According to the present invention, a flat electric wire includes: a plurality of conductor parts arranged in parallel and in contact with each other; and an insulator configured to cover the plurality of conductor parts together, wherein the plurality of conductor parts include stranded wires formed by twisting wires made of a first metal, and single wires made of a second metal that is more easily plastically deformed than the first metal.

[0010] According to the present invention, it is possible to provide a flat electric wire capable of achieving both shape retention and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a cross-sectional view showing a flat electric wire according to an embodiment of the present invention.

[0012] Figure 2is a stress-strain diagram showing the correlation between stress and strain for pure copper and pure aluminum.

[0013] Figure 3 It is shown Figure 1 A chart of conductor sizes for single wires is shown.

[0014] Figure 4 It is a graph showing Examples and Comparative Examples.

[0015] Figures 5A to 5C is a process diagram showing the status of the shape retention test, wherein Figure 5A is the first step, Figure 5B is the second step, and Figure 5C It’s the third step. DETAILED DESCRIPTION

[0016] Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the embodiments described below, and the embodiments may be appropriately changed without departing from the gist of the present invention. In the embodiments to be described below, there may be a portion in which the illustration and description of a part of the configuration are omitted, and needless to say, within the scope of not contradicting the contents to be described below, known or well-known techniques are appropriately applied to the details of the omitted techniques.

[0017] Figure 1 1 is a cross-sectional view showing a flat electric wire according to an embodiment of the present invention. Figure 1 As shown, the flat electric wire 1 according to the present embodiment includes a plurality of conductor parts 10 and an insulator 20 .

[0018] The plurality of conductor parts 10 are elongated conductive linear bodies for transmitting power, signals, etc., and include stranded wires 11 and single wires 12 arranged in parallel and in contact with each other. In the present embodiment, the plurality of conductor parts 10 are composed of four stranded wires 11 and one single wire 12. The stranded wire 11 is formed by twisting a plurality of wires 11a made of a first metal (e.g., pure copper). The single wire 12 is made of a second metal (e.g., pure aluminum) that is more easily plastically deformed than the first metal.

[0019] Figure 2 is a stress-strain diagram showing the correlation between stress and strain for pure copper and pure aluminum. Figure 2 As shown, pure copper has such a characteristic that in the stress-strain diagram, before reaching strain α1, pure copper has a certain slope α2, and when the strain α1 is exceeded, pure copper has a slope α3. Here, when the yield point is obtained based on the yield stress of 0.2% (that is, when a straight line with a slope α2 is drawn from 0.2% strain and the intersection with the pure copper performance is obtained), the yield point is at strain α4. Therefore, it can be said that pure copper elastically deforms when the strain is below α4, and plastically deforms when the strain exceeds α4.

[0020] Figure 2 The pure aluminum shown has such a characteristic that in the stress-strain diagram, when the strain β1 is reached, the pure aluminum has a certain slope β2, and when the strain β1 is exceeded, the pure aluminum has a slope β3. Here, when the yield point is obtained based on the yield stress of 0.2% (that is, when a straight line with a slope β2 is drawn from the strain of 0.2% and an intersection with the performance of pure aluminum is obtained), the yield point is at the strain β4. Therefore, it can be said that pure aluminum elastically deforms when the strain β4 is below, and plastically deforms when the strain β4 is exceeded. In particular, the strain β4 is smaller than the strain α4, and pure aluminum is more easily plastically deformed than pure copper. In this way, the second metal used for the single wire 12 is more easily plastically deformed than the first metal forming the stranded wire 11.

[0021] In the present embodiment, the first metal is, for example, pure copper, and the second metal is pure aluminum, but is not particularly limited to these metals.

[0022] Refer again Figure 1 . Figure 1 The illustrated single wires 12 preferably have a conductor size that is equal to or less than the resistance of the stranded wires 11 . Figure 3 It is shown Figure 1 When the first metal is pure copper and the second metal is pure aluminum, the cross-sectional area and outer diameter of the conductor of the single wire 12 are similar to those of the stranded wire 11. Figure 3 The relationship shown.

[0023] Specifically, when the cross-sectional area of ​​the stranded wire 11 is 1sq, the cross-sectional area of ​​the single wire 12 is 1.6sq or more. Similarly, when the cross-sectional area of ​​the stranded wire 11 is 2sq, 3sq, 5sq, 8sq, 9sq, 10sq, 12sq and 15sq, the cross-sectional area of ​​the single wire 12 is 3.3sq, 4.9sq, 8.1sq, 13.0sq, 14.7sq, 16.3sq, 19.5sq and 24.4sq or more, respectively. When the outer diameter of the stranded wire 11 is 1.2mm, the outer diameter of the single wire 12 is 1.4mm or more. Similarly, when the outer diameter of the stranded wire 11 is 1.9mm, 2.2mm, 3.1mm, 4.0mm, 4.2mm, 4.5mm, 5.0mm and 5.3mm, the outer diameter of the single wire 12 is 2.0mm, 2.5mm, 3.2mm, 4.1mm, 4.3mm, 4.6mm, 5.0mm and above 5.6mm respectively.

[0024] Thus, by setting the conductor size of the single wire 12 so that the resistance of the single wire 12 is equal to or smaller than the resistance of the stranded wire 11, an increase in resistance due to a part of the plurality of conductor portions 10 being made of different metals can be suppressed.

[0025] Refer again Figure 1 .exist Figure 1In the multiple conductor parts 10 shown, the twisted wires 11 and the single wires 12 are arranged symmetrically in the width direction. In the present embodiment, since the conductor part 10 is composed of four twisted wires 11 and a single single wire 12, the single wire 12 is arranged in the center of the five conductor parts 10. The configuration is not particularly limited to the configuration in which the single wire 12 is arranged in the center, as long as the multiple conductor parts 10 are arranged symmetrically in the width direction. For example, the conductor part 10 can be implemented by four twisted wires 11 and two single wires 12 arranged at both ends of the four twisted wires 11.

[0026] The insulator 20 covers the plurality of conductor portions 10 together. The insulator 20 is made of a resin having a Young's modulus of 35 MPa or less (e.g., soft PVC). This is because the use of a resin having a Young's modulus of 35 MPa or less as the insulator 20 can easily ensure shape retention. More specifically, for example, when the first metal is pure copper and the second metal is pure aluminum, and the plurality of conductor portions 10 are implemented by four strands 11 and one single wire 12 disposed in the center, the shape can be maintained when bent 90° with R30.

[0027] Examples and comparative examples will be described below. Figure 4 is a diagram showing an embodiment and a comparative example.

[0028] exist Figure 4 In the comparative example shown, the plurality of conductors consisted of five pure copper strands. The strands had a yield stress of 155 MPa and a Young's modulus of 13 GPa. The insulator had a yield stress of 0.8 MPa and a Young's modulus of 33 MPa.

[0029] In the embodiment, the plurality of conductors are composed of four stranded wires made of pure copper and one single wire made of pure aluminum and arranged in the center. The properties of the stranded wires are the same as those in the comparative example. The yield stress of the single wire is 30 MPa, and the Young's modulus is 68 GPa. The insulator is the same as that in the comparative example.

[0030] Figures 5A to 5C is a process diagram showing the status of the shape retention test, wherein Figure 5A is the first step, Figure 5B is the second step, and Figure 5Cis the third step. The test device T shown in Figure 5 includes a first fixture T1 and a second fixture T2. The cross-sectional shape of the first fixture T1 is a concave shape with the upper side being the open side, and has a curved shape for performing a 90° bend of R30 when viewed from the side. When viewed from the side, both ends of the first fixture T1 serve as a loading portion P for the flat wire. The first fixture T1 includes a first member T11 and a second member T12, and has a structure divided at the center of the bend. The second fixture T2 has rigidity for bending the flat wires shown in the embodiments and comparative examples, and has a curved shape for performing a 90° bend of R30 when viewed from the side. The second fixture T2 is disposed above the first fixture T1 and moves up and down.

[0031] First, in the shape retention test, e.g. Figure 5A In the first step, the flat electric wires according to the embodiment and the comparative example are placed linearly on the placement portion P of the first jig T1. Figure 5B As shown in FIG. 1 , in the second step, the second jig T2 is moved downward. Thus, the flat electric wire placed on the mounting portion P is bent. Thereafter, as shown in FIG. Figure 5C As shown, the second jig T2 is further moved downward, and the flat electric wire is bent by R30 to 90°. Thereafter, the second jig T2 is moved upward, and the flat electric wire is taken out.

[0032] As a result of such a test, the flat electric wire according to the embodiment maintained the 90°

[0033] However, the flat cable according to the comparative example did not maintain the 90° bent state.

[0034] Therefore, it can be confirmed that the flat electric wire 1 including the plurality of conductor portions 10 having the stranded wires 11 and the single wires 12 is superior in shape retaining performance to the flat electric wire including only the stranded wires 11. It was also found that if four stranded wires 11 made of pure copper and the single wire 12 made of pure aluminum and disposed in the center are provided, and if the Young's modulus is 33 MPa, the shape can be retained.

[0035] As described above, according to the flat electric wire 1 in the present embodiment, since the plurality of conductor portions 10 include the stranded wires 11 formed by stranding wires made of a first metal, flexibility can be easily ensured. In addition, the plurality of conductor portions 10 include the single wires 12 made of a second metal that is more easily plastically deformed than the first metal. Therefore, for example, when the flat electric wire 1 is bent at a bending portion, the single wires 12 are easily plastically deformed, and the bent shape is easily maintained. Therefore, it is possible to provide a flat electric wire 1 that can achieve both shape retention and flexibility.

[0036] Since the conductor size of the single wire 12 is set so that the resistance of the single wire 12 is equal to or smaller than the resistance of the stranded wire 11 , an increase in resistance due to the presence of the single wire 12 in the stranded wire 11 can be suppressed.

[0037] The strands 11 and the single wires 12 are arranged symmetrically in the width direction. Therefore, for example, when the strands 11 are arranged on one side in the width direction and the single wires 12 are arranged on the other side in the width direction, the strands 11 arranged only on one side in the width direction generate a force tending to restore the original shape when bent, resulting in deformation. However, by arranging the strands 11 and the single wires 12 symmetrically, the occurrence of deformation can be reduced.

[0038] When the second metal is pure aluminum, since the Young's modulus of the insulator 20 is 35 MPa or less, the stress of the insulator 20 can be prevented from exceeding the shape-retaining performance of pure aluminum, thereby maintaining the shape.

[0039] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and may be modified without departing from the gist of the present invention, and known or publicly known technologies may be combined.

[0040] For example, in this embodiment, the number of the plurality of conductors 10 is five, but it is not particularly limited thereto, and may be more than two and less than four, or more than six. The number of the stranded wires 11 is not limited to four, and may be more than one and less than three, or more than five. Similarly, the number of the single wires 12 may be more than two. Figure 1 In the illustrated example, the number of the wires 11 a is seven, but the number is not limited thereto, and the number may be more than two and less than six, or may be more than eight.

[0041] In the above-described embodiment, the plurality of conductor parts 10 are arranged in a row of five to form a single-layer structure, but the present invention is not particularly limited thereto, and the conductor parts may be stacked in two or more layers.

[0042] This application is based on Japanese patent application (No. 2023-002582) filed on January 11, 2023, the contents of which are incorporated herein by reference.

[0043] 1: Flat wire

[0044] 10: Multiple conductor parts

[0045] 11: Twisted wire

[0046] 11a: Line

[0047] 12: Single line

[0048] 20: Insulator

Claims

1. A flat electric wire comprising: A plurality of conductor portions arranged in parallel and in contact with each other; as well as an insulator configured to cover the plurality of conductor portions together, The plurality of conductor parts include stranded wires formed by twisting wires made of a first metal, and single wires made of a second metal that is more easily plastically deformed than the first metal.

2. The flat electric wire according to claim 1, in, The conductor size of the single wire is set so that the resistance of the single wire is equal to or smaller than the resistance of the stranded wire.

3. The flat electric wire according to claim 1, in, The stranded wires and the single wires are arranged symmetrically in a width direction.

4. The flat electric wire according to claim 1, in, The second metal is pure aluminum, and Wherein, the Young's modulus of the insulator is less than 35 MPa.

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