JP2007080706A - Shielded cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shielded cable far more excellent in twist property compared with a braid. <P>SOLUTION: This shielded cable has a shield layer formed by braiding a strand formed of thin wires on the periphery of the insulating layer of a conductor, in lieu of a beltlike wire bundle formed by fixing thin wires in a lateral line, while winding it from two directions crossing each other with the same pitch as that of a braid obtained by weaving the wire bundle. In this shielded cable, 6 to 13 thin wires having diameters of 0.055 - 0.215mm are twisted in the strand, and 6 thin wires are disposed and twisted with one wire as a center on its periphery in the strand. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shielded cable, and more particularly to a shielded cable in which a shield layer is knitted while winding a stranded wire instead of a braid.

  Conventionally, wiring for electrical connection of sensors and electrical components in factories and vehicles has been conducted to prevent noise from entering or emitting noise to the outside. Electric wires (hereinafter referred to as “shielded cables”) provided with a shield layer on the outer periphery of the insulating layer of the wires and core wires are often used. In this case, in particular, in shielded cables for automobiles, for example, shielded cables used for in-vehicle multimedia such as in-vehicle cameras and car navigation systems, it is necessary to facilitate wiring with bending as a shield layer. Cables are widely used.

  A braid is a bundle of strips made of, for example, copper thin wires arranged in a horizontal row and fixed in a spiral shape in multiple bundles from two intersecting directions so as to almost completely cover the outer periphery of the insulating layer of the conductor. It refers to a structure knitted up and down while being wound around, and by covering the outer periphery of the insulating layer of the conducting wire with a strand (layer), the transmission of electromagnetic waves between the conducting wire and the outside is cut.

In addition, the number of strands constituting one strand is called the number, and the number of strands constituting the braid is called the number. However, in the case of an automobile wire, when the wire diameter is about 8 mm If the number of strikes is 24, the number of possessions is about 6 to 12, and the diameter of the strand is about 0.08 mm to 0.145 mm. Similarly, if the number of strikes is 36, the number of possessions is about 6 to 12, and the diameter of the strand is about 0.055 mm to 0.085 mm. Furthermore, if the number is small, the diameter of the strand increases.
The winding pitch is about 50 mm when the diameter of the braid is about 6 mm (Patent Document 1).
JP-A-1-232923

  In recent years, demands on the safety and reliability of devices have become increasingly severe. Shielded cables are no exception. That is, for example, for use in automobiles, electric cars, hybrid cars, off-road cars, off-road bikes, etc. have been developed or are already being used for automobiles as well as in-vehicle multimedia. And since these automobiles are used for a longer period of time than conventional automobiles and are used for various severe uses, not only the vehicle body but also the shielded cable can maintain the mechanical strength for a longer period of time than before. It is requested.

In addition, even ordinary automobiles are required to withstand long-term use and severe use more than before, and shielded cables are no exception.
For this reason, shielded cables that are currently in practical use are not necessarily sufficient to meet such requirements.

  Specifically, as described above, braids are widely used in current automotive shielded cables. However, braids are used in places where twists are longer than they are currently used, or where twists beyond current levels occur. If there is, there is a risk that the wire will break. In other words, since the strip-shaped strand bundles are knitted up and down while being spirally wound from two directions intersecting each other, each strand of the strand bundle is constrained in a strip shape, Bending and stretching are not free. As a result, when the electric wire is repeatedly twisted, it is easily broken because it is made of soft copper and thin wire.

In addition, if a rupture occurs, a sharp fracture surface because it is a metal may damage a resin insulating coating or the like.
For this reason, development of the shield cable which has the tolerance with respect to twist more than before was desired.

The present invention has been made for the purpose of solving the above problems, and is a shielded cable in which a plurality of stranded wires are knitted up and down instead of a strip-shaped strand bundle fixed in a horizontal row. It is.
The invention of each claim will be described below.

The invention described in claim 1
Instead of a strip-shaped strand bundle in which fine wires are fixed in a horizontal row on the outer periphery of the insulating layer of the conducting wire, the strands formed from the fine wires cross each other at the same pitch as the braid formed by weaving the strand bundle 2 A shielded cable having a shield layer woven while being wound from a direction.

In the invention of this claim, instead of a braid manufactured by weaving a strip-shaped wire bundle in which thin wires are fixed in a horizontal row on the outer periphery of the insulating layer of the conductive wire, the thin wire (originally constituting a bundle of braids) The strands are twisted to form a stranded wire, and the stranded wire is wound in the same manner as a braided braided strand bundle, that is, with the same number of strikes and the same pitch, so the shielding performance is impaired. The twist of the shield layer is improved without any problem. That is, twisting with a small force and fatigue strength against twisting are greatly improved.
That is, when twisting is applied to the shielded cable, each thin wire that forms a stranded wire (in order to distinguish it from a braided wire, it is described as “thin wire” in the stranded wire) is not strongly constrained to each other, unlike the braided wire. Bend and stretch. For this reason, excessive stress is not generated.

Moreover, it is preferable that the number of “knitting while winding from two intersecting directions” is the same in terms of manufacturing and the like.
In addition, “conductive wire insulation layer” includes cases where it also serves as an insulation layer for other wires, such as ground wires, and “conductive wire” is not limited to a single wire, but also includes stranded wires, etc. Is an object of the present invention regardless of signal lines, power cables, and the like.

Invention of Claim 2 is the said shield cable, Comprising:
The stranded wire is a shielded cable in which 6 to 13 fine wires having a diameter of 0.055 mm to 0.215 mm are stranded.

In the invention of this claim, since the stranded wire constituting the shield layer is formed by twisting 6 to 13 fine wires having a diameter of 0.055 mm to 0.215 mm, the braid currently used as a shield cable and The same thin wire will be used, and the arrangement and handling of the thin wire is convenient.
The diameter and the number of twists of the fine wire depend on the strength required for the shielded cable, the diameter of the conductor, etc. Generally, if the shielded cable is thin, the diameter of the fine wire becomes smaller and the pitch of the twisted wire is the same. Then, the diameter of the fine wire and the number of twists are inversely proportional.
However, from the viewpoint of the shielding effect, it is different if the power flowing through the conductor and the external noise source are particularly strong, but the diameter of the stranded wire is 0.14 mm or less and the number of twists is 8 or less.

Invention of Claim 3 is the said shielded cable, Comprising:
The stranded wire is a shielded cable characterized in that six fine wires are arranged on the outer periphery around a single fine wire and are twisted.

In the invention of this claim, when twisting acts on the stranded wire, the thin wire at the center thereof is not restrained by the insulating layer or the insulating sheath because there is another fine wire on the outer periphery at the time of deformation accompanying it. In addition, it is not restricted by other fine wires. Similarly, the fine wire on the outer periphery is not constrained by other fine wires, and further, the fine wire at the center is wound around the outside, so that it is rich in expansion and contraction on the same principle as the coil spring. For this reason, the tolerance with respect to the twist of a shield layer improves greatly.
Furthermore, since a stranded wire having six fine wires arranged around the center of one fine wire is generally used, it is easy to manufacture.

Invention of Claim 4 is the said shielded cable, Comprising:
The shielded cable is characterized in that a pitch angle for winding the stranded wire is 20 degrees to 54 degrees.

In the invention of this claim, since the pitch angle is appropriate, the bending fatigue strength is also increased. The pitch angle is preferably about 35 to 50 degrees.
For this reason, for example, when the outer diameter of the insulating layer is about 5.9 mm to 6.4 mm, the pitch is preferably about 18 mm to 22 mm in terms of resistance to repeated bending.
Here, the pitch angle refers to an angle α satisfying tan α = d × π / p, where d is the outer diameter of the shield layer and x is the pitch. Note that the pitch refers to an interval when the same stranded wire comes at an interval in the length direction of the shielded cable when the stranded wire is wound around the insulating layer at an equal angle. The same applies to the braid.

The invention described in claim 5
On the outer periphery of the insulating layer of the conducting wire, one strand centered on a thin wire having a diameter of 0.10 mm to 0.145 mm and six twisted wires arranged on the outer periphery are twisted from two crossing directions from 10 in each direction. The shielded cable is characterized by having a shield layer braided while being wound at a pitch of 18 mm to 50 mm by 14 pieces.

  In the present invention, the shielded cable is excellent in bending strength, torsional strength, and shielding performance. More preferably, the diameter of the thin wire is 0.12 mm ± 10%, and the number of stranded wires is 12 in each direction.

The invention described in claim 6
On the outer periphery of the insulating layer of the conductive wire, one strand centered on a thin wire having a diameter of 0.075 mm to 0.125 mm and six strands arranged on the outer periphery are twisted and twisted from 16 intersecting directions from two intersecting directions. A shielded cable characterized by having a shield layer braided while winding 20 pieces at a pitch of 18 mm to 50 mm.

  In the present invention, the shielded cable is excellent in bending strength, torsional strength, and shielding performance. The diameter of the thin wire is preferably 0.08 mm ± 10%, and the number of stranded wires is preferably 18 in each direction.

The invention according to claim 7 is the shielded cable,
The shield layer is a shielded cable having an outer diameter of 6 mm to 10 mm.

  In the invention of this claim, since the outer diameter is appropriate, the shielded cable is excellent in bending strength, twisting strength, and shielding performance.

The invention according to claim 8 is the shielded cable,
The thin wire is a shielded cable characterized by being a copper wire.

In the invention of this claim, since the thin wire is a soft copper wire, it is easy to manufacture a stranded wire and to weave while winding the wire from two directions intersecting the outer periphery of the insulating layer of the stranded wire.
In addition, since the material is soft, when the wire passes through the stranded wire die, the electrical contact of each thin wire is made good by pressing from the die, and the electromagnetic shielding effect is also increased.
Here, the “copper wire” includes not only a pure copper wire and an electric copper wire, but also a pure copper wire plated with tin or the like, an electric copper wire, etc. as long as the flexibility and ease of processing are not lost.

  In the present invention, instead of a braid manufactured by weaving a strip of strands in which thin wires are fixed in a horizontal row on the outer periphery of the insulating layer of the conducting wire, the fine wires are twisted to form a stranded wire. Since the shield layer is braided while being wound from two directions intersecting each other at the same pitch as the braid obtained by knitting the strip-shaped wire bundle, the twistability is improved while maintaining a sufficient shield performance.

  Further, unlike the braid, the shield layer is a twisted wire, so that the shield cable itself maintains a sufficient shield performance and improves the twistability.

  Hereinafter, the present invention will be described based on the best mode. In addition, this invention is not limited to the following embodiment. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

(Description of structure)
The structure of the shielded cable according to the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram conceptually showing a cross section orthogonal to the length direction of a shielded cable. FIG. 2 is a diagram conceptually showing the outer shape of the shield layer of this shielded cable as viewed from the direction perpendicular to the length direction of the wire. FIG. 3 is a diagram conceptually showing a cross section of the stranded wire perpendicular to the length direction thereof.
In these drawings, 10 is a conducting wire for transmitting a signal, 20 is an insulating layer for insulating the conducting wire, and 30 is a shield layer for blocking the transmission of electromagnetic waves between the conducting wire 10 and the outside. Reference numeral 40 denotes an insulating sheath that protects the entire shielded cable, and reference numeral 50 denotes a shielded cable.

As shown in FIG. 1, the shield layer 30 is formed on the outer periphery of the insulating layer 20. Further, as shown in FIG. 2, a plurality of lines are wound at equal intervals from two intersecting directions, and are alternately knitted up and down at the same intersection as the braid. For this reason, the shield layer has a so-called rhombus network structure.
Further, as shown in FIG. 3, the outer peripheral winding forming the shield layer 30 is composed of a stranded wire 31 in which six fine wires 36 having the same diameter are wound around the outer periphery of one fine wire 35 at the center. .
For this reason, in the stranded wire, the fine wires have a considerable degree of freedom mechanically while maintaining electrical contact with each other.

When manufacturing this shielded cable, the shield layer 30 is pressed in the center direction from the outer periphery with a die through the insulating sheath 40 in the step of forming the shield layer 30 by covering the outer periphery with the insulating sheath 40. In order to solidify the insulation sheath 40, the stranded wires 31 intersecting from the two directions are solidified in a state of being in electrical and firm contact at the intersection. Furthermore, since the fine wire is made of soft copper, electrical contact by pressing is further improved.
However, since the resin is much more flexible than copper when deformed by an external force, there is virtually no constraint on the deformation of individual thin wires by the resin of the insulating layer or sheath.

(Explanation of performance test)
A performance test of the shielded cable 50 according to the present embodiment will be described.
(1) Shielded cable that was tested The outline of the shielded cable that was tested is as follows.
The number of strikes (the same as the braid, the same number of strands wound from two intersecting directions spirally wound, the total number of stranded wires knitted up and down) is 24, the diameter of the strand is 0.12 mm, the outer diameter of the shield layer Is 6.0 mm, and the outer diameter of the insulating sheath is 6.0 mm. The material for the insulating layer is polyethylene blended with a flame retardant, and the material for the insulating sheath is polyurethane blended with a flame retardant.
The outline of the shielded cable with the shield layer subjected to the comparative test is as follows.
The number of hits is 24, the number of handles is 7, the diameter of the strand is 0.12 mm, and the rest is the same as the shield wire of the embodiment.

(2) Torsion test The test method will be described with reference to FIG. As shown in FIG. 4, one end of a shielded cable 50 having a length of 0.3 m was fixed to the wall 60, the other end was twisted by ± 15 degrees, and the number of times until breakage was measured. In FIG. 4, the cross section at the left end of the shielded cable is strictly an ellipse, and the wire diameter is reduced near the wall 60, but these points are ignored to make the content of the torsion test easier to understand. .
As a result of the test, as shown in FIG. 5, in the shielded cable of the embodiment, the stranded wire was broken after 30000 times.
On the other hand, in the shielded cable with the braided shield layer, the braid broke after 10,000 times. The number of striking of the braid is actually seven as described above, but if this is drawn accurately, the figure will be too fine and difficult to read, so the braid of FIG. Yes.

(Shield performance test)
A comparative test of the shielding performance of the shielded cable in which the shield layer was formed by braiding with the shielded cable of the above embodiment was conducted. As the test method, an absorption clamp method was used, and the leakage of current from the electric wire to be tested was moved along the electric wire for each frequency band, and the peak was measured.
The test results are shown in FIG. In FIG. 6, the solid line is an actual measurement value of the shielded cable of the embodiment, and the broken line is an actual measurement value of the shielded cable of the comparative example and shows a portion different from the embodiment. Therefore, in the frequency region where only the solid line is shown, the shielding effect of the shielded cable of the embodiment and the shielded cable of the comparative example is the same.

  As shown in FIG. 6, the frequency is slightly different in the vicinity of 0.01 MHz as in the range from 0.4 MHz to 1 MHz. However, in the range from 0.01 MHz to 1 MHz, a conventionally used braid is adopted. It can be seen that it has the same or almost the same performance as the shielded cable.

It is a figure which shows notionally the cross section orthogonal to the length direction of a shielded cable. It is a figure which shows notionally the external shape which looked at the shield layer of the shielded cable from the direction orthogonal to the length direction of a line. It is a figure which shows notionally the cross section orthogonal to a direction for the length of a strand wire. It is a figure which shows notionally the test method of a twist test. It is a figure which shows a twist test result. It is a figure which shows a shield performance test result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Conductor 20 Insulating layer 30 Shield layer 31 Stranded wire 35 Center thin wire 36 Outer peripheral thin wire 40 Insulating sheath 50 Shield cable 60 Fixed wall

Claims (8)

  Instead of a strip-shaped strand bundle in which fine wires are fixed in a horizontal row on the outer periphery of the insulating layer of the conducting wire, the strands formed from the fine wires cross each other at the same pitch as the braid formed by weaving the strand bundle 2 A shielded cable having a shield layer braided while being wound from the direction.   2. The shielded cable according to claim 1, wherein the twisted wire is formed by twisting 6 to 13 fine wires having a diameter of 0.055 mm to 0.215 mm.   The shielded cable according to claim 1 or 2, wherein the twisted wire is twisted with six fine wires arranged on the outer periphery with a single thin wire as the center.   The shielded cable according to any one of claims 1 to 3, wherein a pitch angle of winding of the stranded wire is 20 degrees to 54 degrees.   On the outer periphery of the insulating layer of the conducting wire, one strand centered on a thin wire having a diameter of 0.10 mm to 0.145 mm and six twisted wires arranged on the outer periphery are twisted from two crossing directions from 10 in each direction. A shielded cable characterized by having a shield layer braided while being wound at a pitch of 18 mm to 50 mm by 14 pieces.   On the outer periphery of the insulating layer of the conductive wire, one strand centered on a thin wire having a diameter of 0.075 mm to 0.125 mm and six strands arranged on the outer periphery are twisted and twisted from 16 intersecting directions from two intersecting directions. A shielded cable characterized by having a shield layer braided while winding 20 pieces at a pitch of 18 mm to 50 mm.   The shield cable according to any one of claims 1 to 6, wherein the shield layer has an outer diameter of 6 mm to 10 mm. The shielded cable according to claim 1, wherein the thin wire is a copper wire.

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