JP2007027040A - Electric cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric cable configured with a plurality of strands made of insulated cores and a sheath covering it, whose cross section shape can be kept circular without inclusion. <P>SOLUTION: The electric cable 11 is configured with the plurality of strands made of the insulated cores 12 each of which consists of an electric conductor 15 and an insulator 16 covering the electric conductor 15, and the sheath 14 which covers a periphery of the plurality of strands. On a surface of each insulated core 12, irregularity (projected stripes 16a etc.) which suppresses mutual sliding of the insulated cores to maintain mutual position relation of the insulated cores in a cable cross section is formed. Since the irregularity 16a suppresses the mutual sliding of the adjacent insulated cores 12, the mutual position relation of the insulated cores 12 in the cable cross section is maintained, therefore the cable cross section shape is kept circular without the inclusion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric cable in which a plurality of insulating cores formed by covering an outer periphery of a conductor with a plurality of insulating cores twisted together and sheathed on the outer periphery, and more particularly to a means for maintaining a circular cable cross section.

  Conventionally, according to the Electrical Appliance and Material Safety Law (Ministry of Economy, Trade and Industry), electrical cables such as CV (crosslinked polyethylene insulated vinyl sheathed cable) and CVV (vinyl insulated vinyl sheathed cable) have a cross-sectional shape with inclusions. It is obliged to finish it in a round shape, and further, the electrical appliance standard, the JIS standard, etc. clearly state that “insert inclusion”.

  FIG. 7A shows an example of this type of electric cable 1, which has a structure in which an inclusion 3 is inserted into a gap between four twisted insulating cores 2 and a sheath 4 is applied. The insulating core 2 is an insulated wire in which an outer periphery of a conductor 5 is covered with an insulator 6. As the inclusion, a string of PP (polypropylene), jute, paper or the like, or an extruded resin is usually employed.

  In order to finish the cross-sectional shape of the cable in a round shape, the inclusion is filled when there is no inclusion around the insulating core 2 and there is a gap 7 between the insulating cores 2 as in the electric cable 1 ′ shown in FIG. When a pressing force from above and below acts on the electric cable 1 '(for example, when it is wound around a drum), the insulating core 2 moves relatively within the cable cross section, the cable cross section becomes flat, and the circular cross section is formed. This is because it cannot be maintained.

  As described above, the purpose of the inclusion is only to round the cross-sectional shape of the cable, and is not essential for the original function of sending electric power or an electric signal. As described above, the inclusion is a string of PP, jute, paper or the like, or an extruded resin, but the inclusion is discharged as waste during wiring work, so that it is necessary to dispose of the waste. There are drawbacks. Further, the cable itself has a drawback that the weight increases due to inclusions.

  The present invention has been made to eliminate the above-mentioned conventional drawbacks, and it is possible to maintain a circular cable cross section without inclusions in an electric cable having a sheath on a plurality of twisted insulating cores. The object is to provide a possible electrical cable.

The invention of claim 1 which solves the above-mentioned problem is an electric cable in which a plurality of insulating cores formed by covering an outer periphery of a conductor with an insulating body are twisted together and a sheath is provided on the outer periphery thereof.
The surface of each insulating core is characterized in that irregularities that suppress the sliding between the insulating cores are formed in order to maintain the mutual positional relationship between the insulating cores in the cable cross section.

  According to a second aspect of the present invention, in the electric cable according to the first aspect of the present invention, there is no inclusion for rounding the cable cross section around the insulating core.

According to a third aspect of the present invention, in the electric cable of the first aspect, the unevenness on the surface of the insulating core is formed by a plurality of protrusions extending in the longitudinal direction.
According to a fourth aspect of the present invention, in the electric cable of the first aspect, the unevenness on the surface of the insulating core is formed by a plurality of grooves extending in the longitudinal direction.
According to a fifth aspect of the present invention, in the electric cable of the first aspect, the unevenness on the surface of the insulating core is formed by making the cross-sectional shape of the insulating core into a circular saw blade shape or a gear shape.

According to a sixth aspect of the present invention, in the electrical cable of the first aspect, the unevenness of the surface of the insulating core is formed by dimples distributed over the entire surface.
According to a seventh aspect of the present invention, in the electrical cable of the first aspect, the unevenness on the surface of the insulating core is formed by small protrusions distributed over the entire surface.

The invention according to claim 8 is an electrical cable in which a plurality of insulating cores formed by covering an outer periphery of a conductor with an insulating body are twisted and a sheath is provided on the outer periphery thereof.
The cross-sectional shape of each insulating core is a polygonal cross-sectional shape.

  According to the electric cable of the first aspect of the present invention, since the unevenness is formed on the surface of each insulating core, slippage between adjacent insulating cores is suppressed by the unevenness. Further, the unevenness on the surface of the insulating core also serves as a suppressive force against slippage between the sheath inner surface and the insulating core surface. Therefore, for example, when a pressing force from above and below is applied to the cable, the insulating core does not move within the cable cross section even if no inclusion is present, and the cable cross section is maintained in a circular shape.

  According to the electric cable of the invention of claim 8, since the cross-sectional shape of the insulating core is a polygonal cross-sectional shape, the sliding between the adjacent insulating cores is suppressed. Further, slippage between the sheath inner surface and the insulating core surface is also suppressed. Therefore, as described above, for example, when a pressing force from above and below acts on the cable, even if there is no inclusion, the insulating core does not move within the cable cross section, and the cable cross section has a circular shape. Maintained.

  Hereinafter, an electric cable embodying the present invention will be described with reference to the drawings.

  FIG. 1 shows an electric cable 11 according to an embodiment of the present invention. FIG. 1A is a sectional view of the electric cable 11, and FIG. 1B is one insulating core 12 in the electric cable 11 of FIG. FIG. This electric cable 11 has a structure in which, for example, four insulating cores 12 are twisted and a sheath 14 is provided on the outer periphery thereof without inclusions. Each insulating core 12 is an insulated wire in which the outer periphery of the conductor 15 is covered with the insulator 16, but the insulating core mutual positional relationship within the cable cross section is maintained on the surface of the insulator 16 (surface of the insulating core 12). In order to achieve this, irregularities that suppress slippage between adjacent insulating cores 12 are formed. In this embodiment, as the irregularities on the surface of the insulating core 12, a plurality of triangular protrusions (irregularities) 16a extending in the cable length direction are formed on the surface of the insulator 16 over the entire circumference. Thereby, the cross-sectional shape of the insulator is generally a circular saw blade shape or a gear shape.

In the electrical cable 11 described above, the four insulating cores 12 in the sheath 14 are arranged in an annular shape in such a manner that adjacent ones are engaged with each other by the surface irregularities 16a. Does not occur. Further, the unevenness 16a on the surface of the insulating core 12 also serves as a suppressive force against slippage between the inner surface of the sheath 14 and the surface of the insulating core 12. Accordingly, the four insulating cores 12 in the sheath 14 maintain the mutual positional relationship in the sheath 14 in a fixed manner even if there are gaps around them (without inclusions). Thereby, even if the pressing force from the up-down direction acts on the electric cable 11, for example, the cable cross-sectional shape is maintained in a circular shape.
Therefore, inclusions are not discharged as waste during wiring work, and the burden of waste disposal is eliminated. In the present situation where the increase in waste is a major problem due to environmental problems, it is extremely meaningful if the structure of the present invention can be adopted and the discharge of inclusions can be eliminated. In addition, since the inclusions are eliminated, the weight of the cable can be reduced. Further, since the inclusion is eliminated, the electric cable can be manufactured at a low cost.

A CVV (vinyl insulated vinyl sheathed cable) having the same structure as that of the electric cable 11 shown in FIG. 1 was prototyped, and an experiment was performed in which a pressing force was applied from above and below. The mutual positional relationship of the insulating cores 12 was maintained, and the cable cross-sectional shape was kept circular.
The prototype electric cable is CVV 1.25 sq × 4 C, and four insulating cores 12 made by applying a vinyl insulator 16 having a thickness of about 0.8 mm on a seven-stranded conductor 15 having a size of 1.25 sq mm are twisted together. This is a control cable in which a non-woven fabric is wound horizontally on the outer periphery and a vinyl sheath 14 having a thickness of about 1.5 mm is applied.

2A to 2D show various examples of the unevenness on the surface of the insulating core.
The insulating core 22 shown in FIG. 2A has a plurality of protrusions (unevenness) 26a extending in the cable length direction on the entire surface of the insulator 26 as the unevenness on the surface, as described above. However, in this embodiment, the cross-sectional shape of the protrusion 26a and the groove 26b formed between the protrusions 26a is rounded.
In this case, similar to the above, adjacent insulating cores 22 mesh with each other at the surface unevenness 26a, and the mutual positional relationship between the insulating cores 22 is maintained without causing any sliding between the insulating cores 22 and the cable cross-sectional shape. Is kept round.

The insulating core 32 shown in FIG. 2 (b) has a plurality of protrusions (unevenness) 36a extending in the length direction on the surface of the insulator 36 as the unevenness on the surface thereof, as described above. However, in this embodiment, the protrusions 36a are square, small and many.
Also in this case, as described above, adjacent insulating cores 32 mesh with each other by the surface irregularities 36a, so that the mutual positional relationship between the insulating cores 32 is maintained without slipping between the insulating cores 32, and the cable cross section. The shape is kept circular. Note that when the groove 36b between the protrusions 36a is small, the insulating cores 32 do not mesh with each other. However, since the friction is sufficiently large, it is possible to prevent sliding from each other.

The insulating core 42 shown in FIG. 2 (c) has a plurality of protrusions (unevenness) 46a extending in the length direction on the surface of the insulator 46 as the unevenness on the surface, as described above. However, in this embodiment, the width of the protrusion 46a is wide and substantially trapezoidal, and the groove 46b between the protrusions 46a is narrow and has an acute angle. Further, the number of the protrusions 46a is small.
In this case, the adjacent insulating cores 42 do not mesh with each other, but the presence of the groove 46b causes a large amount of friction and can prevent sliding.

The insulating core 52 shown in FIG. 2 (d) has a plurality of protrusions (unevenness) 56a extending in the length direction on the surface of the insulator 56 as the unevenness on the surface, as described above. However, in this embodiment, the protrusions 56a have an acute triangular cross-sectional shape, are provided at intervals, and the number is small.
In the case of this insulating core 52, the sharp-angled ridges 56a prevent mutual sliding.

FIG. 3 shows still another embodiment of the unevenness provided on the surface of the insulating core. 3A is a perspective view of the insulating core 62, and FIG. 3B is a partially enlarged sectional view.
The insulating core 62 of this embodiment is provided with a large number of small depressions, that is, dimples (unevenness) 66a distributed over the entire surface as the unevenness provided on the surface.
In the case of the insulating core 62, a large friction is generated due to the presence of a large number of dimples 66a, and it is possible to prevent them from slipping each other.

FIG. 4 shows still another embodiment of the unevenness provided on the surface of the insulating core. 4A is a perspective view of the insulating core 72, and FIG. 4B is a partially enlarged sectional view.
The insulating core 72 of this embodiment is provided with a large number of small protrusions (unevenness) 76a distributed over the entire surface as the unevenness provided on the surface.
In the case of this insulating core 72, a large friction is generated by the presence of a large number of small protrusions 76a, and it is possible to prevent sliding.

FIG. 5 shows an electric cable 81 of another embodiment. 4A is a sectional view of the electric cable 81, and FIG. 4B is an enlarged sectional view of the insulating core 82. FIG.
The insulating core 82 of the electric cable 81 of this embodiment is obtained by making the cross-sectional shape of the insulator 86 an octagon. Each side of the octagon is denoted by 86a.
When four insulating cores 82 are twisted, as shown in the drawing, adjacent insulating cores 82 are in contact with each other on both sides 86a of sides 86a 'on the cable center side of each insulating core 82. When twisted in such an arrangement that a rectangular gap 87 is formed at the side 86a 'on the center side of 82, the movement of the insulating core 82 within the sheath 14 is effectively suppressed, and the mutual positional relationship of the insulating core 82 is stable. Thus, the cable cross-sectional shape is maintained circular.

FIG. 6 shows an electric cable 91 according to another embodiment. 2A is a cross-sectional view of the electric cable 91, and FIG. 2B is an enlarged cross-sectional view of the insulating core 92. FIG.
The electric cable 91 of this embodiment has seven insulating cores 92, that is, a seven-core cable, and the insulating core 92 is obtained by making the cross-sectional shape of the insulator 96 hexagonal. Each side of the hexagon is indicated by 96a.
In this case, when six insulating cores 92 are twisted around one insulating core 92 arranged at the center of the cable, a gap is generated between each side 96a of the insulating core 92 having a hexagonal shape as illustrated. Twisted together. Therefore, the movement of the insulating core 92 within the sheath 14 is effectively suppressed, the mutual positional relationship between the insulating cores 92 is stabilized, and the cable cross-sectional shape is maintained in a circular shape.

  The insulating core 82 in FIG. 5 is octagonal and the insulating core 92 in FIG. 6 is hexagonal, but other polygonal shapes are also possible.

The electric cable of the present invention can be applied to a power cable, a control cable, a communication cable, and other various electric cables. Further, the present invention can be applied if the number of cores of the electric cable is two or more. Further, the material / structure of the conductor, the material of the insulator, the material of the sheath, etc. are not particularly limited.
In addition, although this invention has a big merit at the point which made the inclusion unnecessary, since it has the effect that a circular maintenance function increases further even if it uses an inclusion together, it is not limited to a thing without an inclusion. . Moreover, even if inclusions are included, it is possible that the amount of inclusions can be reduced, or inclusions that are convenient for waste disposal can be selected.

The electrical cable of one Example of this invention is shown, (a) is sectional drawing of an electrical cable, (b) is an expanded sectional view of one insulation core in (a). The other Example about the unevenness | corrugation of the surface of an insulating core is shown, (a)-(d) is sectional drawing of the insulating core of a respectively different Example. An example in which a large number of dimples are distributed on the surface of the insulating core is shown, (a) is a perspective view of the insulating core, and (b) is an enlarged sectional view of one dimple portion. The Example which distributed many small protrusions on the surface of an insulating core is shown, (a) is a perspective view of an insulating core, (b) is an expanded sectional view of one small protrusion part. The electrical cable of the other Example of this invention is shown, (a) is sectional drawing of an electrical cable, (b) is an expanded sectional view of one insulation core in (a). The electric cable of the further another Example of this invention is shown, (a) is sectional drawing of an electric cable, (b) is an expanded sectional view of one insulation core in (a). It is sectional drawing which shows the conventional electric cable. It is a figure explaining the problem when the inclusion is eliminated in the conventional electric cable.

Explanation of symbols

11, 81, 91 Electrical cables 12, 22, 32, 42, 52, 62, 72, 82, 92 Insulating core 15 Conductors 16, 26, 36, 46, 56, 66, 76, 86, 96 Insulators 16a, 26a , 36a, 46a, 56a Projections (unevenness)
26b, 36b, 46b Groove 66a Dimple 76a Small protrusions 86a, 86a ′, 96a (octagonal or hexagonal) sides

Claims (8)

In an electric cable in which a plurality of insulating cores formed by coating an insulator on the outer periphery of a conductor are twisted together and a sheath is applied to the outer periphery thereof,
An electrical cable, characterized in that a surface of each insulating core is provided with irregularities that suppress slippage between the insulating cores in order to maintain the mutual positional relationship between the insulating cores in the cable cross section.   2. The electric cable according to claim 1, wherein there is no inclusion for making the cable cross section circular around the insulating core.   2. The electric cable according to claim 1, wherein the unevenness on the surface of the insulating core is formed by a plurality of protrusions extending in the longitudinal direction.   2. The electric cable according to claim 1, wherein the unevenness of the surface of the insulating core is formed by a plurality of grooves extending in the longitudinal direction.   2. The electric cable according to claim 1, wherein the unevenness of the surface of the insulating core is formed by making the cross-sectional shape of the insulating core into a circular saw blade shape or a gear shape.   2. The electric cable according to claim 1, wherein the unevenness of the surface of the insulating core is formed by dimples distributed over the entire surface.   2. The electric cable according to claim 1, wherein the unevenness of the surface of the insulating core is formed by small protrusions distributed over the entire surface. In an electric cable in which a plurality of insulating cores formed by coating an insulator on the outer periphery of a conductor are twisted together and a sheath is applied to the outer periphery thereof,
An electric cable characterized in that the cross-sectional shape of each insulating core is a polygonal cross-sectional shape.

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