Flat wire

Abstract

To provide a flat electric wire capable of achieving a good balance between shape retention and flexibility.SOLUTION: 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 that coats the plurality of conductor parts 10 all at once, and the plurality of conductor portions 10 is composed of a twisted wire 11 in which a first metal element wire 11a is twisted, and a single wire 12 composed of second metal that is more likely to be plastically deformed than the first metal, the single wire 12 has a conductor size at which electric resistance becomes equal to or lower than electric resistance of the twisted wire 11. The twisted wire 11 and the single wire 12 are arranged in a symmetrical arrangement in a width direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, flat electric wires have been proposed in which the conductor is covered with an insulator to give the entire wire a flat shape. Some of these flat electric wires have a conductor made of a bus bar (see, for example, Patent Document 1), while others have a conductor made of a plurality of stranded wires formed by twisting a number of elemental wires and arranged in parallel (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-53377 A [Patent Document 2] Patent Publication No. 2021-157968 Summary of the Invention [Problem to be solved by the invention]

[0004] The flat electric wire described in Patent Document 1 has excellent shape retention but poor flexibility because the conductor is composed of a bus bar. In contrast, the flat electric wire described in Patent Document 2 has excellent flexibility but poor shape retention because the conductor is composed of multiple twisted wires. For this reason, in the past, the flat electric wire described in Patent Document 1 was used in places where shape retention was required, and the flat electric wire described in Patent Document 2 was used in places where flexibility was required. Therefore, a flat electric wire that combines shape retention and flexibility is desired.

[0005] The present invention has been made to solve the above-mentioned problems in the conventional art, and an object of the present invention is to provide a flat electric wire that can achieve both shape retention and flexibility. [Means for solving the problem]

[0006] The flat electric wire of the present invention is a flat electric wire comprising a plurality of conductor portions arranged in parallel and in contact with each other, and an insulator that collectively covers the plurality of conductor portions, wherein the plurality of conductor portions include a stranded wire formed by twisting wires of a first metal, and a solid wire formed of a second metal that is more susceptible to plastic deformation than the first metal. Effect of the Invention

[0007] According to the present invention, it is possible to provide a flat electric wire that is capable of achieving both shape retention and flexibility. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a flat electric wire according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a stress-strain diagram showing the correlation between stress and strain for pure copper and pure aluminum. [Diagram 3] 2 is a table showing the conductor sizes of the single wire shown in FIG. 1. [Figure 4] 1 is a table showing examples and comparative examples. [Diagram 5] FIG. 1 is a process diagram showing the shape retention test, where (a) is the first process, (b) is the second process, and (c) is the third process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and can be modified as appropriate within the scope of the present invention. In addition, in the embodiments shown below, some configurations are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are appropriately applied to the details of the omitted technologies within the scope of the contents described below.

[0010] Fig. 1 is a cross-sectional view showing a flat electric wire according to an embodiment of the present invention. As shown in Fig. 1, the flat electric wire 1 according to the embodiment is configured to include a plurality of conductors 10 and an insulator 20.

[0011] The multiple conductor sections 10 are long conductive wires for transmitting power, signals, etc., and include twisted wires 11 and solid wires 12 arranged in parallel and in contact with each other. In this embodiment, the multiple conductor sections 10 are composed of four twisted wires 11 and one solid wire 12. The twisted wire 11 is formed by twisting a large number of element wires 11a made of a first metal (e.g., pure copper). The solid wire 12 is composed of a second metal (e.g., pure aluminum) that is more easily plastically deformed than the first metal.

[0012] Fig. 2 is a stress-strain diagram showing the correlation between stress and strain for pure copper and pure aluminum. As shown in Fig. 2, pure copper has a certain gradient α2 up to strain α1 in the stress-strain diagram, and when strain α1 is exceeded, the characteristic has a gradient α3. Here, if the yield point is found based on 0.2% proof stress (i.e., if a straight line with gradient α2 is drawn from strain 0.2% and the intersection with the pure copper characteristic is found), the yield point is strain α4. Therefore, it can be said that pure copper can be elastically deformed up to strain α4, and when strain α4 is exceeded, it undergoes plastic deformation.

[0013] In addition, the pure aluminum shown in FIG. 2 has a characteristic that has a certain gradient β2 up to the strain β1 in the stress-strain diagram, and has a gradient β3 when the strain exceeds β1. Here, if the yield point is found based on the 0.2% proof stress (i.e., if a straight line with the gradient β2 is drawn from the strain of 0.2% and the intersection with the pure aluminum characteristic is found), the yield point is the strain β4. Therefore, it can be said that pure aluminum can be elastically deformed up to the strain β4, and when the strain exceeds β4, it undergoes plastic deformation. 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 in the solid wire 12 is more easily plastically deformed than the first metal constituting the stranded wire 11.

[0014] In this embodiment, the first metal is, for example, pure copper and the second metal is pure aluminum, but they are not limited to these metals.

[0015] Please refer to Fig. 1 again. The solid wire 12 shown in Fig. 1 preferably has a conductor size that is equal to or smaller than the electrical resistance of the twisted wire 11. Fig. 3 is a chart showing the conductor size of the solid wire 12 shown in Fig. 1. When the first metal is pure copper and the second metal is pure aluminum, the cross-sectional area and outer conductor diameter of the solid wire 12 have the relationship shown in Fig. 3 with respect to the twisted wire 11.

[0016] Specifically, when the cross-sectional area of ​​the stranded wire 11 is 1 sq, the cross-sectional area of ​​the solid wire 12 is 1.6 sq or more. Similarly, when the cross-sectional area of ​​the stranded wire 11 is 2 sq, 3 sq, 5 sq, 8 sq, 9 sq, 10 sq, 12 sq, and 15 sq, the cross-sectional areas of the solid wire 12 are 3.3 sq, 4.9 sq, 8.1 sq, 13.0 sq, 14.7 sq, 16.3 sq, 19.5 sq, and 24.4 sq or more, respectively. Also, when the outer diameter of the stranded wire 11 is 1.2 mm, the outer diameter of the solid wire 12 is 1.4 mm or more. Similarly, when the outer diameters of the stranded wire 11 are 1.9 mm, 2.2 mm, 3.1 mm, 4.0 mm, 4.2 mm, 4.5 mm, 5.0 mm, and 5.3 mm, the outer diameters of the solid wire 12 are 2.0 mm, 2.5 mm, 3.2 mm, 4.1 mm, 4.3 mm, 4.6 mm, 5.0 mm, and 5.6 mm or more, respectively.

[0017] In this way, by setting the conductor size of the solid wire 12 to be equal to or smaller than the electrical resistance of the twisted wire 11, an increase in electrical resistance caused by some of the multiple conductor portions 10 being made of different metals can be suppressed.

[0018] Referring again to FIG. 1, in the multiple conductor portions 10 shown in FIG. 1, the twisted wires 11 and the solid wires 12 are arranged symmetrically in the width direction. In this embodiment, the conductor portion 10 is composed of four twisted wires 11 and one solid wire 12, so that the solid wire 12 is provided in the center of the five conductor portions 10. Note that, as long as the multiple conductor portions 10 are arranged symmetrically in the width direction, the configuration is not particularly limited to one in which the solid wire 12 is provided in the center. For example, the conductor portion 10 may be composed of four twisted wires 11 and two solid wires 12 provided at both ends of the four twisted wires 11.

[0019] The insulator 20 collectively covers the multiple conductor parts 10. The insulator 20 is made of a resin (e.g., soft PVC) with a Young's modulus of 35 MPa or less. By using a resin with a Young's modulus of 35 MPa or less as the insulator 20, shape retention can be easily ensured. More specifically, for example, when the first metal is pure copper and the second metal is pure aluminum, and the multiple conductor parts 10 are made of four twisted wires 11 and one solid wire 12 arranged in the center, the shape can be retained in a 90° bend with R30.

[0020] Next, examples and comparative examples will be described. Fig. 4 is a table showing examples and comparative examples.

[0021] In the comparative example shown in Fig. 4, the multiple conductors were composed of five strands of pure copper. The yield stress of the stranded wire was 155 MPa and the Young's modulus was 13 GPa. The insulator had a yield stress of 0.8 MPa and a Young's modulus of 33 MPa.

[0022] In the embodiment, the multiple conductors were composed of four strands of pure copper and one solid wire of pure aluminum placed in the center. The properties of the stranded wire were the same as those of the comparative example. The yield stress of the solid wire was 30 MPa and the Young's modulus was 68 GPa. The insulator was the same as that of the comparative example.

[0023] FIG. 5 is a process diagram showing the state of the shape retention test, where (a) is the first process, (b) is the second process, and (c) is the third process. The test device T shown in FIG. 5 includes a first jig T1 and a second jig T2. The first jig T1 has a cross-sectional shape that is a concave shape with the upper side open, and is curved to perform a 90° bending of R30 when viewed from the side. When viewed from the side, both ends of the first jig T1 are the placement parts P of the flat electric wire. The first jig T1 includes a first member T11 and a second member T12, and is structured to be divided at the center of the curve. The second jig T2 has rigidity for bending the flat electric wire shown in the examples and comparative examples, and is curved to perform a 90° bending of R30 when viewed from the side. This second jig T2 is provided above the first jig T1 and is configured to move up and down.

[0024] First, in the shape retention test, a first step is performed as shown in Fig. 5(a). In this first step, the flat electric wires according to the embodiment and the comparative example are linearly placed on the placement part P of the first jig T1. Next, in a second step, the second jig T2 is moved downward as shown in Fig. 5(b). This bends the flat electric wires placed on the placement part P. Thereafter, as shown in Fig. 5(c), the second jig T2 is further moved downward, and the flat electric wires are bent at 90° with R30. Thereafter, the second jig T2 is moved upward, and the flat electric wires are taken out.

[0025] As a result of such a test, the flat electric wire according to the embodiment maintained a 90° bent state of R30, but the flat electric wire according to the comparative example could not maintain a 90° bent state.

[0026] Therefore, it was confirmed that the flat electric wire 1 having a plurality of conductor portions 10 including the twisted wires 11 and the solid wires 12 has a shape retention performance superior to that of a flat electric wire having only the twisted wires 11. It was also found that the shape is retained when the wire is provided with four twisted wires 11 made of pure copper and a solid wire 12 made of pure aluminum arranged in the center and has a Young's modulus of 33 MPa.

[0027] In this way, according to the flat electric wire 1 of this embodiment, the plurality of conductor portions 10 have the twisted wires 11 formed by twisting wires of a first metal, so that flexibility can be easily ensured. Furthermore, the plurality of conductor portions 10 have the solid wires 12 formed of a second metal which is more easily plastically deformed than the first metal. Therefore, for example, when the flat electric wire 1 is used at a bending portion and bent, the solid wires 12 are easily plastically deformed and easily retain the bent shape. Therefore, it is possible to provide a flat electric wire 1 that can achieve both shape retention and flexibility.

[0028] Furthermore, since the solid wire 12 has a conductor size that is equal to or smaller than the electrical resistance of the twisted wire 11, an increase in electrical resistance due to the presence of the solid wire 12 in the twisted wire 11 can be suppressed.

[0029] In addition, the twisted wires 11 and the solid wires 12 are arranged symmetrically in the width direction. For this reason, for example, if the twisted wires 11 are arranged on one side in the width direction and the solid wires 12 are arranged on the other side in the width direction, the twisted wires 11 arranged on only one side in the width direction will exert a force that tries to return to its original shape when bent, which will cause distortion, but by arranging them symmetrically, it is possible to suppress the occurrence of distortion.

[0030] Furthermore, when the second metal is pure aluminum, the Young's modulus of the insulator 20 is 35 MPa or less, so that the stress of the insulator 20 can be prevented from exceeding the shape retention ability of the pure aluminum, thereby enabling shape retention.

[0031] The present invention has been described above based on an embodiment, but the present invention is not limited to the above embodiment, and modifications may be made without departing from the spirit of the present invention, and if possible, known or well-known technologies may be combined.

[0032] For example, in this embodiment, the plurality of conductor portions 10 are configured by five wires, but are not limited to this, and may be two to four wires, or six or more wires. The number of stranded wires 11 is not limited to four wires, and may be one to three wires, or five or more wires. Similarly, the number of solid wires 12 is not limited to one wire, and may be two or more wires. In the example shown in FIG. 1, the number of strands 11a is seven wires, but are not limited to this, and may be two to six wires, or eight or more wires.

[0033] Furthermore, in the above embodiment, the plurality of conductor portions 10 are arranged in a row of five to form a single-layer structure, but the present invention is not limited to this, and the conductor portions may be laminated in two or more layers. [Explanation of symbols]

[0034] 1:Flat electric wire 10: Multiple conductor parts 11: Stranded wire 11a: Plain wire 12: Single line 20: Insulator

Claims

1. A flat electric wire including a plurality of conductor portions arranged in parallel and in contact with each other, and an insulator collectively covering the plurality of conductor portions, The plurality of conductor portions include a stranded wire formed by stranding strands of a first metal, and a solid wire formed of a second metal that is more easily plastically deformed than the first metal. A flat electric wire characterized by:

2. The solid wire has a conductor size that is equal to or smaller than the electrical resistance of the stranded wire.

2. The flat electric wire according to claim 1 .

3. The stranded wire and the solid wire are arranged symmetrically in the width direction.

2. The flat electric wire according to claim 1 .

4. the second metal is pure aluminum; The insulator has a Young's modulus of 35 MPa or less.

2. The flat electric wire according to claim 1 .

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