JP4875447B2 - cable - Google Patents

Description

  The present invention relates to an improvement in a cable having at least a pair of insulated wires or one or more optical fiber cores, particularly a cable used for aerial use.

To one or more optical fiber cores in which a plurality of insulated wires or optical fibers coated with a plurality of insulated wires or optical fibers formed by twisting pairs or quad-twisting (insulated four wires) of an insulated wire with an insulation coating on a conductor Various cables have been manufactured with a coating layer (usually also referred to as a sheath) and, if necessary, further provided with support wires. These cables are used in many places and variously, for example, by being installed in an aerial (Patent Document 1).
A typical cable of this type is shown in FIG.

FIG. 2 shows a cross section of an aerial cable with a very common support line having a pair of insulated wires 3 twisted inside.
The aerial cable shown in FIG. 2 is made of, for example, a twisted insulated wire 3 made of PVC, polyethylene, or the like, and a covering layer 5a having a thickness of about 0.5 mm and an outer diameter of 4.0 mm. This is manufactured by winding the product around a support 4 provided with a coating layer 5b made of PVC or polyethylene.
Moreover, the method of forming the coating layers 5a and 5b at the same time while vertically attaching the support 4 to the twisted insulated wire 3 is also generally performed.
In FIG. 2, reference numeral 1 denotes a conductor, and reference numeral 2 denotes an insulating coating.

JP-A-8-212841

By the way, when this type of cable is installed as an aerial cable, characteristic deterioration of unknown cause may occur over time. As a result of many years of investigation and research, the inventors of the present application have found that the cause of this characteristic deterioration is due to the spawning behavior of the cicada, particularly the bearfish, on the cable in summer.
Kuma-zemi originally has the property of laying an oviduct into a tree trunk or branch in nature and laying eggs inside the tree trunk or branch. For some reason, however, there is a cable in which an imaginary cable is mistaken for a tree trunk or a branch, and a spawning tube is pierced into the cable covering layer 5a to lay eggs inside.

When the laying tube is inserted into the covering layer 5a in this manner, moisture such as rainwater enters the cable from the opened hole, and when the laying tube penetrates the covering layer 5a, the insulated wire 3 causes poor insulation. There is also a possibility.
Since it is not common sense that such cable characteristic deterioration is caused by the oviposition behavior of the bearfish, it is presumed that the cause has not been investigated for a long time. As a result, at present, sufficient measures have not been taken.

  Accordingly, an object of the present invention is to provide a cable that can suitably prevent deterioration in characteristics mainly due to the egg-laying behavior of bearfish.

In order to achieve the above object, a cable according to claim 1 of the present invention includes a pair of insulated wires or one or more optical fiber cores, and the pair of insulated wires or one or more optical fiber cores. An inner coating layer applied to the outer coating layer, and an outer coating layer that is coated on the outer side of the inner coating layer, has a plurality of ridges on the inner side, and the tips of the plurality of ridges contact the outer surface of the inner coating layer The total thickness of the inner coating layer and the outer coating layer is 1.9 mm or more and 2.5 mm or less .

Furthermore, the cable according to claim 2 of the present invention is characterized in that the thickness of the inner covering layer is 0.4 mm or more and 0.6 mm or less.

In addition, the cable according to claim 3 of the present invention is the cable according to any one of claims 1 to 2 , wherein the outer surface of the outer covering layer is continuously provided with a notch in the longitudinal direction. It is characterized by.
Furthermore, the cable according to claim 4 of the present invention is characterized in that in the cable according to any one of claims 1 to 3 , the cable further includes a support wire outside the outer covering layer.

  According to the present invention as described above, since the total thickness of the inner coating layer and the outer coating layer constituting the cable is set to a predetermined thickness, the durability against the kuma-zemi or the like, that is, the characteristic deterioration with time. No cable can be provided.

Hereinafter, the cable of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of the cable of the present invention. As shown in FIG. 1, the cable of the present invention includes, for example, an insulating coating 2 made of polyethylene or the like on a copper conductor 1 (which may be a single wire or a stranded wire) having an outer diameter of 0.65 mm. An inner covering layer 5a made of polyethylene or PVC (polyvinyl chloride) was applied to a twisted pair of insulated wires 3 having an outer diameter of 1.25 mm so that the outer diameter d was about 4 mm.
In addition, if the thickness t of the inner coating layer 5a is set to 0.4 mm to 0.6 mm, it becomes the same as an ordinary cable that is very commonly used. Therefore, in other words, as long as the thickness t of the inner covering layer 5a is set to 0.4 mm to 0.6 mm, it is not necessary to specially manufacture a cable as a measure against the bear seminar. This cable is preferable because it has the advantage that it can be used as it is as a cable with an inner covering layer 5a shown in FIG.

Next, the outer coating layer 6 made of PVC or polyethylene or the like is applied to the outside of the inner coating layer 5a, and the support 4 made of galvanized steel wire or the like having an outer diameter of 1.2 mm is made of PVC or polyethylene. It was wound around what gave the coating layer 5b, and it was set as the cable with a support wire.
The outer covering layer 6 has a plurality of protrusions 8 extending in the cable longitudinal direction on the inner side thereof. The tips of the plurality of protrusions 8 are in contact with the outer surface of the inner covering layer 5a, and the cable having the inner covering layer 5a is positioned and supported at the approximate center position of the cable.
The adjacent protrusions 8 and 8 and the inner coating layer 5a form a gap 9.

As shown in FIG. 1, by providing an outer covering layer 6 having a gap 9 inside, there is a gap 9 inside than a cable having a so-called solid outer covering layer 6 without a gap 9 inside. Therefore, there is an advantage that the weight of the cable can be reduced.
Further, the weight reduction means that the extrusion amount (weight per unit area) of the outer coating layer 6 can be reduced. In this case, when the outer coating layer 6 is extrusion coated on the inner coating layer 5a, the outer coating layer 6 It is preferable that the inner covering layer 5a and the insulated wire 3 are thermally deteriorated by the heat of the heat, and the tips of the protrusions 8 of the outer covering layer 6 are difficult to adhere to the surface of the inner covering layer 5a.
Furthermore, since both the inner covering layer 5a and the outer covering layer 6 are difficult to adhere to each other, the outer covering layer 6 can be easily peeled off from the inner covering layer 5a during laying work or connection work. Excellent in connection and workability.
In this way, in the cable of the present invention, the outer covering layer 6 having the gap 9 inside is formed on the inner covering layer 5a, so that the outer covering layer 6 is made of less material, that is, lighter in weight. It has a great feature that it can be formed thicker.
Further, by providing the outer covering layer 6 having the protrusions 8 as described above, even if a flying object is blown by a strong wind or the like and collides with the cable, a cushion effect of the air gap 9 is also added, and the cable is damaged. A significant reduction effect is also obtained. Similarly, even if this cable touches a tree or a wall of an adjacent building, the damage is greatly reduced.

As shown below, it has the same structure as the cable shown in FIG. 1, a cable of varying thickness T ₀ of the thickness t and the outer coating layer 6 of the inner coating layer 5a and 30 different prototype, the prototype About 1-30, the durability with respect to the egg-laying behavior of a bearfish was verified.
The durability verification method was carried out by collecting a large number of bear swallows in July, which is the egg-laying period of bear swallows, and placing each of the bear swallows and the above-mentioned prototypes of the cables in a case and allowing them to stand for 10 days.

  After being left for 10 days, the prototype cable was taken out of the case and the surface of the cable was visually inspected. And, only the outer covering layer 6 is damaged by the oviduct (but does not penetrate the outer covering layer 6), ◎, penetrates the outer covering layer 6 and also the inner covering layer 5a. A mark was given to those that had external scratches but did not penetrate the inner coating layer 5a, and x to those that had scratches penetrating both the outer coating layer 6 and the inner coating layer 5a. The results are shown in Table 1.

From Table 1, the thickness t and the total thickness T of the thickness T ₀ of the outer coating layer 6 of the inner coating layer 5a is, durability becomes allowable range for cicadas becomes more than 1.9 mm, becomes equal to or larger than 2.4mm It can be seen that the cable can be completely protected.
On the other hand, as can be seen from Table 1, the total thickness T is preferably 2.5 mm or less in order to reduce the weight of the cable. Thus, when the total thickness T is 2.5 mm or less, the weight of the cable can be further reduced in addition to improving the durability against the spawning behavior of the blackfish, for example, from the viewpoint of reducing the cable cost or fictitious It is also preferable from the viewpoint of laying workability.

  By the way, the cross-sectional shape of the outer covering layer 6 shown in FIG. 1 is substantially octagonal because there are eight protrusions 8 extending in the cable longitudinal direction. Generally, due to the extrusion by the extruder, it tends to be a polygon corresponding to the number of the ridges 8, but of course the outer covering layer 6 may be a polygon or a circle.

  Further, a notch 10 extending in the cable longitudinal direction is provided on the outer surface of the outer covering layer 6, for the purpose of facilitating the tearing of the outer covering layer 6 at the time of connection with a device, for example. In the cable shown in FIG. 1, another notch 10 is provided at a position opposite to 180 degrees, and a pair of notches 10 is provided as a whole, but the number of notches 10 is not particularly limited. Moreover, although the cable shown in FIG. 1 has only one pair of insulated wires 3 inside, a plurality of pairs may be used.

Furthermore, in the cable shown in FIG. 1, the cable with the outer covering layer 6 and the cable with the covering layer 5b applied to the support 4 are twisted to form a cable with a support wire. The inner coating layer 5 a may be integrated with the outer coating layer 6. Alternatively, a support wire in which the covering layer 5b is provided on the support 4 in advance may be prepared, and this may be vertically attached to a cable on which the outer covering layer 6 is provided, and the two may be integrated with a lashing wire.
Of course, depending on the application, as an example, in laying for a very short distance, a cable provided with the outer covering layer 6 without the support wire can be used as it is.

Moreover, in the said Example, although the insulated wire 3 is provided inside the inner coating layer 5a, one or more optical fiber core wires may be sufficient. In this case, if the total thickness T of the thickness T ₀ of the thickness t and the outer coating layer 6 of the inner cladding layer 5a than 1.9 mm, deterioration of characteristics of the optical fiber according to egg-laying behavior of cicadas, especially This is preferable because there is no risk of breakage or deterioration of transmission loss.

As described above, according to the present invention, the total thickness of the inner coating layer and the outer coating layer constituting the cable by providing a gap inside the outer coating layer is determined by using the material for the outer coating layer. Without increasing so much, it is possible to provide a cable that can be thick enough to reach the oviposition tube of the burdock, and has excellent durability against cicada laying behavior such as burdock.
In addition, the weight of the entire cable can be reduced, and the inner coating layer and the outer coating layer can be easily peeled off. Thus, a cable excellent in cable connection workability and installation workability can be provided.

It is a cross-sectional view which shows one Example of the cable of this invention. It is a cross-sectional view of a conventional cable.

Explanation of symbols

1 conductor 2 insulation coating 3 insulated wire 5a inner coating layer 6 outer coating layer 8 ridge 9 gap 10 notch

Claims (4)

A pair or more of insulated wires or one or more optical fiber cores; an inner coating layer applied to the outside of the pair of or more insulated wires or one or more optical fiber cores; and an outer coating of the inner coating layer A plurality of ridges on the inside, and an outer coating layer with tips of the plurality of ridges contacting the outer surface of the inner coating layer, the thickness of the inner coating layer and the outer coating layer A cable having a total thickness of 1.9 mm to 2.5 mm . The cable according to claim 1, wherein a thickness of the inner covering layer is 0.4 mm or more and 0.6 mm or less. Cable according to any one of claims 1 to 2, characterized in that notches in succession in the longitudinal direction is provided on an outer surface of the outer coating layer. Cable according to any one of claims 1 to claim 3, further comprising a support wire to the outside of the outer coating layer.

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