JP2006032076A - Electric wire for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric wire for an automobile for accomplishing both of improvement in tensile strength and reduction in a diameter. <P>SOLUTION: This electric wire for an automobile is provided with a compressed conductor constructed by arranging a plurality of peripheral element wires formed of copper or a copper alloy around a single center element wire formed of stainless steel. The peripheral element wires surrounding the center element wire are arranged in a single layer to be brought into tight contact with each other. A cross sectional area of the conductor is 0.10-0.30 mm<SP>2</SP>, while a ratio C of the cross sectional area of the center element wire to that of the conductor is expressed by an expression äA/(A+B)}×100 [%]. In this expression, A represents the cross sectional area of the center element wire, while B represents the sum of the cross sectioanl areas of the peripheral element wires. The ratio C ranges from 19.6% to 33.3%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric wire for an automobile, and more particularly to an electric wire for an automobile that can meet demands for improvement in tensile strength and a reduction in diameter.

In an automobile, a wire harness in which a large number of electric wires are bundled is used for electrical connection to an electrical component or the like. Some electric wires used for this wire harness have a conductor having a twisted wire structure in which a plurality of strands are twisted together. A typical conductor (element assembly) of this type of electric wire is shown in FIG. In the figure, reference numeral 1 denotes a conductor, which has a stranded wire structure in which six peripheral strands 3 are arranged in close contact with each other around a single central strand 2 and twisted together. Conventionally, copper or a copper alloy has been generally used for the central strand 2 and the peripheral strand 3 constituting the conductor having such a stranded structure. In addition, the diameters of the central strand 2 and the peripheral strand 3 are the same. Furthermore, as a cross-sectional area of a conductor, a wire having a nominal cross-sectional area of about 0.35 mm ² when used in an automobile room and a nominal cross-sectional area of about 0.50 mm ² when used in an engine room is common. .

  On the other hand, in recent years, demands for improving tensile strength and reducing the diameter of an electric wire for automobiles are increasing. However, in the case of the electric wire of FIG. 1 described above, in order to improve the tensile strength, it is necessary to increase the conductor diameter, and it has not been possible to satisfy the demand for a reduction in diameter.

  In the present invention, in the case of the same conductor diameter, a high tensile strength can be obtained, and even when the conductor diameter is reduced, the tensile strength of the conventional automobile electric wire can be maintained. An object of the present invention is to provide an automobile electric wire capable of obtaining a tensile strength higher than that of a conventional one depending on the degree of diameter.

  As a result of intensive studies, the present inventor has made it possible to improve the tensile strength by using stainless steel for the center wire, and to limit the relationship between the center wire and the cross-sectional area of the conductor to an appropriate relationship. The present inventors have found that the tensile strength can be secured while preventing bending breakage even in response to the demand for narrowing the diameter, and the present invention has been completed.

The invention described in claim 1
Around a single central strand made of stainless steel, a compressed conductor is formed by arranging a plurality of peripheral strands made of copper or copper alloy so as to surround the central strand in a single and close contact with each other. An electric wire for an automobile,
The cross-sectional area of the conductor is 0.10 to 0.30 mm ² ;
And the ratio C of the cross-sectional area of the said center strand with respect to the cross-sectional area of the said conductor represented by a following formula is 19.6 to 33.3%, It is an electric wire for motor vehicles characterized by the above-mentioned.
Ratio of the cross-sectional area of the central strand to the cross-sectional area of the conductor C = {A / (A + B)} × 100 [%]
(However, in the above formula, A is the cross-sectional area of the central strand, and B is the sum of the cross-sectional areas of the peripheral strands.)

  In the said invention, since stainless steel is used as a center strand, the tensile strength higher than the electric wire in which the conventional copper or copper alloy was used can be obtained.

  In addition, since a compressed conductor is used as a conductor composed of a central strand and a peripheral strand, it is possible to efficiently reduce the diameter of the conductor.

In addition, if the cross-sectional area of the conductor is too small, even if stainless steel is used for the center strand, sufficient tensile strength cannot be obtained, and if it is too large, the demand for reducing the diameter cannot be met. It causes a decrease in flexibility. From such a viewpoint, the cross-sectional area of the conductor is preferably 0.10 to 0.30 mm ² .

In addition, since the ratio C of the cross-sectional area of the central strand to the cross-sectional area of the conductor is 19.6% or more, it can be satisfied even for an electric wire having a cross-sectional area of the conductor of 0.10 to 0.30 mm ^2. It is possible to obtain the strength and the tensile strength (hereinafter referred to as terminal fixing force) at the terminal fixing portion, which is regarded as important in the electric wire for automobiles.

  On the other hand, it was found that if the ratio C of the cross-sectional area of the central strand to the cross-sectional area of the conductor is increased too much, the flexibility is deteriorated. However, in the said invention, since the ratio C is 33.3% or less, it is hard to produce a bending fracture | rupture and it has the sufficient flexibility.

  Moreover, in the said invention, since the surrounding strand is arrange | positioned only single around the center strand, a surrounding strand can be stably arrange | positioned with respect to a center strand.

If the conductor diameter is reduced to the limit, it will not be able to withstand a large impact load. On the other hand, if the diameter is not sufficiently advanced, the number of wires that can handle the high degree of digitization in today's automobiles will be met. I can't. When these are taken into consideration, a practically preferable conductor cross-sectional area is 0.13 to 0.25 mm ² . In this case, an appropriate value is 19.6 to 29.1% as the ratio C of the cross-sectional area of the central strand to the cross-sectional area of the conductor.

The invention according to claim 2 corresponds to this preferable aspect,
The conductor has a cross-sectional area of 0.13 to 0.25 mm ² ;
And the ratio C of the cross-sectional area of the said center strand with respect to the cross-sectional area of the said conductor is 19.6-29.1%, The electric wire for motor vehicles of Claim 1 characterized by the above-mentioned.

When the reduction in diameter of the conductor is most advanced while considering the tensile strength, impact load, and flexibility, the practically optimal conductor cross-sectional area when used in an automobile interior is 0.13 mm ^{2 in the} nominal cross-sectional area. It is. In this case, 24.5 to 29.1% is an appropriate value as the ratio C of the cross-sectional area of the central strand to the cross-sectional area of the conductor.

The invention according to claim 3 corresponds to this preferable aspect,
A cross-sectional area of the conductor is 0.13 mm ² in a nominal cross-sectional area;
And the ratio C of the cross-sectional area of the said center strand with respect to the cross-sectional area of the said conductor is 24.5 to 29.1%, Furthermore, it is used in a motor vehicle interior, The object for motor vehicles of Claim 1 characterized by the above-mentioned. It is an electric wire.

In the same way as described above, the most practical cross-sectional area of a conductor when used in an engine room when the diameter of the conductor is most advanced while considering the tensile strength, impact load and bendability is the nominal section. The area is 0.22 mm ² . In this case, 24.5 to 29.1% is an appropriate value as the ratio C of the cross-sectional area of the central strand to the cross-sectional area of the conductor.

The invention according to claim 4 corresponds to this preferable aspect,
A cross-sectional area of the conductor is 0.22 mm ² in a nominal cross-sectional area;
2. The automobile according to claim 1, wherein a ratio C of a cross-sectional area of the central strand to a cross-sectional area of the conductor is 24.5 to 29.1%, and is used in an engine room. Wire.

  The electric wire for automobiles of the present invention satisfies the requirements for reduction in diameter and improvement in tensile strength required for today's automobile electric wires in a range close to practical limits, and is also an electric wire for automobiles that also considers flexibility. is there.

  FIG. 2 is a cross-sectional view showing a state before the conductor is compressed, after the conductor is compressed, and after the insulation coating in one structural example of the electric wire for an automobile according to the present invention, and there are eight peripheral wires. Moreover, FIG. 3 is sectional drawing which shows the state before compression of a conductor in the example of seven peripheral strands.

  In FIG. 3, reference numeral 21 denotes a conductor (combination form of strands) before compression, and seven peripheral strands 23 made of copper or a copper alloy are single around a single central strand 22 made of stainless steel. It is closely arranged in the circumferential direction and twisted together to form a stranded wire structure. The cross-sectional area of the central strand 22 is set so that a predetermined relationship with the cross-sectional area of the conductor 21 is established. The assembly form of such strands is compressed in the center direction by using, for example, a compression die to obtain a compressed conductor. Then, an insulating coating is provided around the compressed conductor directly or via a shield layer to obtain an automobile electric wire.

  1 has a configuration in which six peripheral strands having the same cross-sectional area are arranged in close contact with each other around the central strand. However, in the automotive electrical wire of the present invention, the cross-sectional area of the central strand is the same. Is set to a predetermined relationship with the cross-sectional area of the conductor, the number of peripheral strands is set to 7 or more.

  Various types of stainless steel can be used as the central element wire of the automobile electric wire of the present invention, and SUS304, SUS316 (both of which are Japanese Industrial Standards) having a high tensile strength are particularly preferable.

  Also, the copper or copper alloy used for peripheral wires can be of various types normally used for electric wires, but pure copper, Cu-Ni-Si alloy from the viewpoint of conductivity, tensile strength, elongation, etc. Cu-Sn alloy, Cu-Cr-Zr alloy and the like are preferable.

  In consideration of the use of the automotive electric wire of the present invention as a wire harness electric wire, the tensile breaking load required for the conductor is 62.5 N or more for an automobile interior, and 100 N or more for an engine room. It is preferable that Similarly, the terminal fixing force is preferably 50 N or more for an automobile interior and 70 N or more for an engine room.

Next, in order to obtain an appropriate range of the ratio C of the cross-sectional area of the center wire to the cross-sectional area of the conductor, the tensile breaking load, terminal fixing force, and number of bending breaks of the conductor under various conditions were obtained.
In the experiment, SUS304 having a tensile breaking strength of 940 MPa was used as the central strand, and pure copper having a tensile breaking strength of 230 MPa was used as the peripheral strand, and a conductor compressed at a compression rate of 10 to 15% was used.

  Regarding the terminal fixing force, the terminal was caulked so that the conductor would not come off, the terminal was fixed, the other end of the conductor was pulled, and the tensile breaking load when the conductor was broken at the terminal fixing portion was measured.

Moreover, the bending fracture test followed the following.
That is, in a constant temperature bath of 23 ° C., as shown in FIG. 4, a weight 4 having a weight of 500 g is hung on the lower end of the conductor, and the conductor is sandwiched between cylindrical mandrels 5 with R = 6 mm. The conductor was bent 90 ° to the left and 90 ° to the right, and one round trip was taken as one bend, and the number of bends until the conductor broke was measured.

  The results of the experiment are shown in Table 1.

From Table 1 it, if the conductor cross-sectional area 0.14 mm ^2, preferably a tensile breaking load 62.5N for automobile interior, in order to realize a terminal holding force 50N, the ratio C or more is required 24.5 percent I understand.
Further, in the case of a conductor having a cross-sectional area of 0.25 mm ² , the ratio C is required to be 19.6% or more in order to realize a preferable tensile breaking load 100 N and terminal fixing force 70 N for the engine room.

The number of bending breaks of the conductor is required to be 150 times or more, preferably 250 times or more. In order to exceed this value, the ratio C is 40. In the case where the cross-sectional area of the conductor is 0.14 mm ² . In the case of 6% and the cross-sectional area of the conductor being 0.25 mm ² , it can be seen that it is necessary to make it 24.5% or less.

The final product as an electric wire for automobiles is provided with an insulation coating around the conductor. As the insulation coating, conventionally used polyvinyl chloride (PVC), polyethylene (including foam), halogen-free material Various resin materials such as tetrafluoroethylene can be used. The thickness of the insulating coating is appropriately set according to the finished outer diameter of the conductor.
Moreover, when providing a shield layer, the conventionally well-known various materials which have a shield effect can be used.

  Examples of the present invention are shown below. The present invention is not limited to the following examples. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

(Example 1)
Sectional area 0.0314Mm ² as center strand before compression, the use of SUS304 of tensile strength 957MPa, cross-sectional area 0.1321Mm ^2, the pure copper of the tensile rupture strength 240MPa used as peripheral strands before compression, the center strand After seven peripheral strands are closely attached to each other, compression is performed with a die, and then a halogen-free material (olefin type) is used as a coating material, and insulation coating is performed by extrusion to obtain an automobile electric wire according to the present invention. It was. Sectional area of the center strand of the resulting wire is 0.0274Mm ^2, the cross-sectional area of the conductor is 0.14 mm ^2, the ratio C of the cross-sectional area of the center strand to the cross-sectional area of the conductor, 19.6 %Met. The tensile breaking load was 59 N, the terminal fixing force was 47 N, and the number of bending breaks was 1186.

(Example 2)
Sectional area 0.0398Mm ² as center strand before compression, the use of SUS304 of tensile strength 949MPa, cross-sectional area 0.1231Mm ^2, the pure copper of the tensile rupture strength 245MPa used as peripheral strands before compression, the center strand Eight peripheral strands are placed in close contact with each other, then compressed with a die, and then a halogen-free material (olefin-based) is used as a coating material, and insulation coating is performed by extrusion to obtain an automotive electric wire according to the present invention. It was. Sectional area of the center strand of the resulting wire is 0.0343Mm ^2, the cross-sectional area of the conductor is 0.14 mm ^2, the ratio C of the cross-sectional area of the center strand to the cross-sectional area of the conductor, 24.5 %Met. The tensile breaking load was 65 N, the terminal fixing force was 52 N, and the number of bending breaks was 906.

It is sectional drawing of the electric wire conductor for motor vehicles of the conventional twisted wire structure (uncompressed conductor). It is sectional drawing which shows the state before the compression in the structural example of the electric wire conductor for motor vehicles by this invention, after compression, and after insulation coating. It is sectional drawing which shows the state before compression of the electric wire conductor for motor vehicles by this invention. It is a conceptual diagram which shows the condition of a bending test.

Explanation of symbols

1, 21 Conductor 2, 22 Center wire 3, 23 Peripheral wire 4 Weight 5 Mandrel

Claims (4)

Around a single central strand made of stainless steel, a compressed conductor is formed by arranging a plurality of peripheral strands made of copper or copper alloy so as to surround the central strand in a single and close contact with each other. An electric wire for an automobile,
The cross-sectional area of the conductor is 0.10 to 0.30 mm ² ;
And the ratio C of the cross-sectional area of the said center strand with respect to the cross-sectional area of the said conductor represented by a following formula is 19.6 to 33.3%, The electric wire for motor vehicles characterized by the above-mentioned.
Ratio of the cross-sectional area of the central strand to the cross-sectional area of the conductor C = {A / (A + B)} × 100 [%]
(However, in the above formula, A is the cross-sectional area of the central strand, and B is the sum of the cross-sectional areas of the peripheral strands.) The conductor has a cross-sectional area of 0.13 to 0.25 mm ² ;
And the ratio C of the cross-sectional area of the said center strand with respect to the cross-sectional area of the said conductor is 19.6-29.1%, The electric wire for motor vehicles of Claim 1 characterized by the above-mentioned. A cross-sectional area of the conductor is 0.13 mm ² in a nominal cross-sectional area;
And the ratio C of the cross-sectional area of the said center strand with respect to the cross-sectional area of the said conductor is 24.5 to 29.1%, Furthermore, it is used in a motor vehicle interior, The object for motor vehicles of Claim 1 characterized by the above-mentioned. Electrical wire. A cross-sectional area of the conductor is 0.22 mm ² in a nominal cross-sectional area;
2. The automobile according to claim 1, wherein a ratio C of a cross-sectional area of the central strand to a cross-sectional area of the conductor is 24.5 to 29.1%, and is used in an engine room. Electric wire.

Images