KR102363059B1 - Shield cable using carbon fiber - Google Patents

Abstract

The present invention relates to a lightweight shielding cable capable of easily calculating the braided density of a shielding braided layer using carbon fibers, maintaining shielding performance, and having flexibility.

Description

Shield cable using carbon fiber

The present invention relates to a shielded cable, and to a lightweight shielded cable while maintaining shielding performance equivalent to that of a conventional metal using carbon fiber.

As the rate of electrical automation of transportation means such as trains, ships, aircraft, and automobiles increases, the frequency of use of various signal/control cables used in transportation means is increasing. The signal/control cable used in the transportation means is sensitive to electromagnetic waves and therefore requires a shielding effect of a certain level or more.

When a metal wire or a metal braid layer is used for electromagnetic wave shielding, the weight and diameter of the cable may increase, so that the fuel efficiency of a vehicle in which the cable is used may deteriorate.

In addition, the cable is difficult to arrange in a transportation means due to its low flexibility, so that the installation workability is deteriorated, and damage to the cable occurs during or after the installation operation. That is, in the case of a conventional cable shielded by using a metal, the weight of the cable increases and flexibility is reduced.

Accordingly, carbon fibers may be used as the shielding layer. Carbon fiber has a density that is 1/4 lower than that of iron and has ten times higher strength. Although carbon fiber is a conductive material, it has low electrical conductivity to replace it with a metal material of a cable. When the metal-coated carbon fiber is used as the shielding layer, a lightweight shielded cable can be manufactured.

However, since the carbon fiber has a very small outer diameter of about 7 μm, it is difficult to calculate the index (set of small wire diameter) as in the conventional metal braid, and because it is necessary to apply the flat shape in one stroke, There is a problem in that it is impossible to design the braided density with the braided density formula applied to the metal braid.

An object of the present invention is to provide a lightweight shielding cable that can easily calculate the braided density of a shielding braided layer using carbon fibers, maintain shielding performance, and have flexibility.

Shielded cable using carbon fiber according to an embodiment of the present invention, at least one conductor; an insulating layer insulating the conductor; and a shielding layer disposed outside the insulating layer, wherein the shielding layer is made by braiding a plurality of carbon fibers composed of at least one strand to which a conductive material coating is applied, and a braided density f of the shielding layer ( %) may satisfy Equation 2 below.

[Equation 2]

In Equation 2 above,

m is the number of strokes of the shielding layer,

d is the wire diameter (mm) of the carbon fiber coated with the conductive material,

B is the width (mm) of one stroke of the shielding layer,

h is the height (mm) of one stroke of the shielding layer,

P is the braided pitch (mm) of the shielding layer,

α is the flattening (°).

In the present invention, the braided density may be 80% or more.

In the present invention, the conductive material coating may be formed of nickel (Ni) or copper (Cu) plating.

In the present invention, the conductive material coating consists of a first plating layer formed on the outer surface of the carbon fiber, and a second plating layer formed on the first plating layer, wherein the first plating layer is more electrically than the second plating layer. It may be made of a metal having higher conductivity, and the second plating layer may be made of a metal having greater corrosion resistance than the first plating layer.

In the present invention, the first plating layer may be made of copper, and the second plating layer may be made of nickel.

In the present invention, an inner sheath layer provided to protect the conductor and the insulating layer may be further included.

In the present invention, the shielding layer may be formed outside the inner sheath layer.

In the present invention, it may further include an external sheath layer formed outside the shielding layer.

According to an embodiment of the present invention, even in the case of carbon fiber whose index selection is difficult, the braid density can be easily calculated, and the shielding performance of the shielded cable is adjusted by calculating the braided density, and the flexibility of the shielded cable is increased, It is possible to reduce the weight of the shielded cable. Accordingly, it is possible to improve the fuel efficiency of the transportation means using the cable according to an embodiment of the present invention.

1 is a cross-sectional view schematically showing a cable according to an embodiment of the present invention.
2 is a cut-away perspective view schematically showing a cable according to an embodiment of the present invention.
3 is a plan view schematically illustrating a structure of a shielding layer of a cable according to an embodiment of the present invention.
4 is a perspective view schematically illustrating a carbon fiber coated with a conductive material.
5 is a cross-sectional view showing a state in which a plurality of carbon fibers are arranged in a line.
6 is a cross-sectional view showing a plurality of carbon fibers constituting one stroke in the shielding layer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed subject matter may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art. Like reference numerals refer to like elements throughout.

1 is a cross-sectional view of a cable according to an embodiment of the present invention, FIG. 2 is a cut-away perspective view of a cable according to an embodiment of the present invention, and FIG. 3 is a shielding layer structure of the cable according to an embodiment of the present invention It is a plan view, and FIG. 4 is a perspective view schematically showing a carbon fiber coated with a conductive material.

1 to 4 , a cable 1000 according to an embodiment of the present invention includes at least one conductor 112 , an insulating layer 116 insulating the conductor 112 , and the insulating layer A shielding layer 140 disposed outside the 116 may be provided.

The conductor 112 may be formed by a stranded wire, aggregation, or a composite of the wire 20 made of any one of conductors such as copper, aluminum, aluminum alloy, or copper-clad aluminum wire.

A separate tape 114 surrounding the conductor 112 may be provided outside the conductor 112 . The separator tape 114 is not essential, and in particular, when the conductor 112 is formed of a thin wire, it may be omitted.

When the separate tape 114 is provided, the insulating layer 116 may be extruded to surround the separate tape 114 . The insulating layer 116 is made of a material having insulating and impact resistance characteristics, and serves to protect and insulate the conductor 112 by covering it.

Specifically, the insulating layer 116 is silicone (Silicone), cross-linked polyethylene (XLPE), cross-linked polyolefin (Cross Linked Polyollefin; XLPO), ethylene-propylene rubber (ethylene-propylene rubber; EPR), polychloride It may be made of vinyl (polyvinyl chloride; PVC) or a mixture thereof.

The conductor 112, the separate tape 114, and the insulating layer 116 form one core 110, and as in the cable 1000 shown in FIGS. 1 and 2, three cores 110 are may be provided, and the number may vary depending on the field to which the cable 1000 is applied, the use environment, the purpose, and the like.

A filler 122 is filled between the plurality of cores 110 to maintain a circular shape, and a binder tape 124 surrounding the circumference of the plurality of cores 110 and the filler 122 may be provided on the outside thereof. have. Here, the plurality of cores 110 , the filler 122 and the binder tape 124 form the core part 120 .

The filler 122 serves to maintain the original shape of the core part 120 and prevent gas permeation, and is preferably made of a non-hygroscopic material that does not absorb moisture.

The binder tape 124 is mainly made of PET material, but is not limited thereto, and serves as a core fixing for fixing the shape at the outermost part of the core part 120 .

An inner sheath layer 130 may be provided outside the core part 120 . The inner sheath layer 130 is used for purposes such as flame retardancy in addition to the role of protecting the conductor 112 therein by absorbing external shock, but is not an essential element and can be omitted.

As the inner sheath layer 130 , both thermoplastic and thermosetting raw materials such as PVC, HF4-1, SHF1, and Chloroprene may be used.

A shielding layer 140 may be provided on the outside of the inner sheath layer 130 . When the inner sheath layer 130 is omitted, the outer side of the core part 120 , that is, the semi-finished product or the insulating layer 116 is wrapped around the outside. A shielding layer 140 may be provided.

On the other hand, the outer sheath layer 150 is provided outside the shielding layer 140, that is, the outermost of the cable 1000 to protect the cable 1000 from external impact or corrosion action. As for the outer sheath layer 150 , like the inner sheath layer 130 , both thermoplastic and thermosetting raw materials such as PVC, HF4-1, SHF1, and Chloroprene may be used. The outer sheath layer 150 is also not essential and may be omitted.

In the present embodiment, the shielding layer 140 may be applied in a knotted form, that is, in a braided form by being inclined at a predetermined angle in both directions with respect to the axial direction of the cable 1000 .

The fiber used as the shielding layer 140 may be carbon fiber. Carbon fiber is a high value-added material that is ¼ lower in density than iron and has ten times higher strength. There are two types of carbon fiber: pitch and pan. The pan system is manufactured by carbonizing PAN (Poly-Acrylonitrile) fibers obtained by polymerizing and spinning acrylonitrile at a high temperature. The pitch system refers to a product manufactured by carbonizing at a high temperature after spun off the residue (pitch) remaining after distillation in the petroleum/coal process.

Carbon fiber is divided into a large tow type and a low tow type according to the number of short fibers constituting the fiber bundle. The low tow type is composed of short fibers with a fiber bundle of 12000 (12K) or less, and is a relatively thin carbon fiber with high mechanical properties and excellent handling properties. The large tow type is composed of 24000 (24K) or more short fibers with a fiber bundle and is a carbon fiber with a large fiber bundle.

The carbon fiber used in the cable is a fan system with high tensile strength, and a low toe type can be used.

Although carbon fiber is a conductive material, it has low electrical conductivity to be replaced by a metallic material for cables. In order to solve this problem, it is possible to increase the electrical conductivity by coating the carbon fiber with a metal.

A conductive material coating may be applied to the surface of the carbon fiber. As an example, copper, gold, aluminum, nickel, silver, etc. may be used for coating the conductive material.

The conductive material coating is, for example, as shown in FIG. 4 , a first plating layer 142a formed on the outer surface of the carbon fiber 141 and a second plating layer formed on the first plating layer 142a ( 142b).

The first plating layer 142a is made of a metal having higher electrical conductivity than the second plating layer 142b, and the second plating layer 142b is made of a metal having a higher corrosion resistance than the first plating layer 142a. can For example, the first plating layer 142a may be made of copper (Cu) having high electrical conductivity, and the second plating layer 142a may be made of nickel (Ni) having high corrosion resistance.

As described above, when the conductive material coating is made through Ni-Cu plating, the maximum electrical resistance may be 10 ⁻¹ Ω or less.

That is, the fiber used in the braid of the present invention, that is, the shielding layer 140, must have a maximum electrical resistance of 10 ^-1 Ω. Reduce. In the case of electroless plating, a first plating layer 142a is formed by plating the outer surface of the carbon fiber 141 with primary Cu, and then, the first plating layer is used to prevent oxidation of Cu constituting the first plating layer 142a. A second plating layer 142b may be formed by plating Ni on the 142a. After that, the metal coating is completed on the fiber surface by UV curing coating.

As described above, when Ni-Cu plating is applied to the surface of the carbon fiber constituting the shielding layer 140 according to an embodiment of the present invention, the problem of reducing the shielding effect when using the conventional simple carbon fiber shielding layer can be solved. .

When following the general standard, a shielding performance of 40 dB or more is required for a signal/control cable, but the general non-plated carbon fiber shielding layer is 40 dB or less in almost all frequency ranges, so the shielding performance is insufficient.

On the other hand, the shielding layer 140 to which the fiber coated with a conductive material is applied by Ni-Cu plating according to the present invention can exhibit equal to or better shielding effect than the conventional metal shielding layer at 40 dB or more in almost all frequency ranges. have.

In the case of metal braiding, N strands of metal wires are added and the sum of C pieces is maintained at a certain angle and twisted together. Here, the number of N strands is called the exponent, the sum of the C pieces is called the number of strokes, and a certain angle is called the piece piece (α). The braid density can be calculated from the index, the number of strokes, and the braid.

However, in the case of forming a braided structure using carbon fibers, the outer diameter of one strand of carbon fibers is very small, about 7㎛, so it is difficult to calculate the index (set of minor wire diameters) as in the conventional metal braid, and since there is no twist, the braid During the process, the width changes depending on the process conditions, and since the flat shape must be applied in one stroke, it is impossible to design the braided density with the braided density formula applied to the metal braiding.

That is, if carbon fibers having a diameter of 7 μm are arranged in a line, it may be as shown in FIG. 5, but it is practically impossible to form one stroke by arranging carbon fibers having a diameter of 7 μm in a line so as not to overlap each other.

During the braiding process, as shown in FIG. 6 , a plurality of carbon fibers overlap each other to constitute one stroke in the form of a width of Bmm and a height of hmm.

When tension is applied according to the braiding process, the carbon fiber becomes narrow in width and increases in height, so the braiding index (n) may be specified as a range as shown in Equation 1 below.

[Equation 1]

Braiding index (n)≤B/h

Accordingly, the braided density f of the shielding layer 140 of the present invention may be expressed by Equation 2 below.

[Equation 2]

In Equation 2, m is the number of strokes of the shielding layer, d is the wire diameter (mm) of the carbon fiber coated with the conductive material, B is the width (mm) of one stroke of the shielding layer, and h is the is the height of one stroke of the shielding layer (mm), Dm is the braided outer diameter (mm) of the shielding layer, P is the braided pitch of the shielding layer (mm), and α is the braided degree (°).

The braided density may be 80% or more.

For shielded cables for automobiles, the standard of shielding effectiveness should satisfy 40dB at 100MHz. However, when the braided density according to Equation 2 of the shielded cable using carbon fiber is less than 80%, it satisfies 40 dB at a low frequency, but does not satisfy the 40 dB criterion at a frequency of 10 MHz or higher.

As such, according to an embodiment of the present invention, the braid density of the shielding braided layer using carbon fibers can be easily calculated, and the shielding performance comparable to that of the metal shielding layer is maintained by adjusting the braided density, while flexibility and lightness It is possible to design a shielded cable with

In addition, the shielding cable 1000 according to the embodiments of the present invention uses carbon fiber coated with a conductive material as the shielding layer 140 , and when only carbon fiber is applied as a shielding layer to the signal/control cable, conductivity is reduced. It is possible to prevent a decrease in shielding performance that may occur due to low shielding performance, maintain a shielding effect of a certain level or more, and improve workability during installation by securing flexibility so that the bending radius does not exceed a certain value with excellent shielding effect.

By preventing the occurrence of signal interference due to poor shielding performance, the reliability of the cable can be secured, and the overall weight of the cable can be reduced, thereby facilitating the transport and installation of the cable. Due to the weight reduction of the cable, it is possible to reduce the weight of the vehicle in which the cable is used, thereby improving the fuel efficiency of the vehicle.

Although the above has been described with reference to one embodiment of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims described below. You can do it. Therefore, if the modified implementation basically includes the elements of the claims of the present invention, all of them should be considered to be included in the technical scope of the present invention.

20: element
110: core
112: conductor
114: separate tape
116: insulating layer
120: core part
122: filler
124: binder tape
130: inner sheath layer
140: shielding layer
150: outer sheath layer

Claims (8)

at least one conductor;
an insulating layer insulating the conductor; and
a shielding layer disposed outside the insulating layer; and
The shielding layer is made by braiding a plurality of carbon fibers composed of at least one strand to which a conductive material coating is applied,
The shielding cable using carbon fiber, characterized in that the braided density f (%) of the shielding layer satisfies the following Equation (2).
[Equation 2]

In Equation 2 above,
m is the number of strokes of the shielding layer,
d is the wire diameter (mm) of the carbon fiber coated with the conductive material,
B is the width (mm) of one stroke of the shielding layer,
h is the height (mm) of one stroke of the shielding layer,
P is the braided pitch (mm) of the shielding layer,
α is the skewness (°). According to claim 1,
The shielding cable using carbon fiber, characterized in that the braided density is 80% or more. According to claim 1,
The shielding cable using carbon fiber, characterized in that the conductive material coating is made of nickel (Ni), copper (Cu), aluminum (Al), gold (Au), or silver (Ag) plating. According to claim 1,
The conductive material coating consists of a first plating layer formed on the outer surface of the carbon fiber, and a second plating layer formed on the first plating layer,
The first plating layer is made of a metal having higher electrical conductivity than the second plating layer,
The second plating layer is a shielding cable using carbon fiber, characterized in that made of a metal having greater corrosion resistance than the first plating layer. 5. The method of claim 4,
The shielding cable using carbon fiber, characterized in that the first plating layer is made of copper, and the second plating layer is made of nickel. 6. The method according to any one of claims 1 to 5,
Shielding cable using carbon fiber further comprising an inner sheath layer provided to protect the conductor and the insulating layer. 7. The method of claim 6,
The shielding layer is a shielding cable using carbon fiber, characterized in that formed outside the inner sheath layer. 8. The method of claim 7,
Shielding cable using carbon fiber further comprising an external sheath layer formed outside the shielding layer.

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