JPH026571Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Background and Purpose of the Invention] The present invention relates to a direct-buried concrete cable that is directly buried in concrete.

Conventionally, wiring in concrete has been carried out by running wires through conduits buried in concrete, but once buried, it is difficult to route wires through conduits that may sometimes include bends. The problem was that the work involved was extremely inefficient and required a lot of work.

In view of these problems with electrical conduits, a so-called directly buried cable in concrete has been proposed, which is provided with an external impact-resistant protective sheath and is directly buried in concrete.

However, although conventional direct-buried concrete cables have the advantage of omitting conduit, once they are directly buried in concrete, it is impossible to take them out without destroying the concrete, and it is difficult to change the indoor layout. If we are unable to meet the often-required wiring changes, and therefore require such wiring changes, we can scrape away the concrete and install a new cable separately from the cable that was once buried. The company had no choice but to use an extremely inconvenient and uneconomical method.

The inventors conducted various studies to see if there was a way to solve the unavoidable problem inherent to direct-buried concrete cables, such as not being able to respond to wiring changes, and then sought a solution for the direct-buried concrete cables themselves.

In other words, we focused on the fact that in direct-buried concrete cables that are integrated into concrete, it is the external protective sheath that is integrated with the cast concrete, but the internal cable core is not integrated with the concrete. However, we thought that by removing the cable core, we could form a hollow part within the external protective sheath that was integrated into the concrete, and that this could be used as a passageway for new wiring materials.

However, in the case of conventional directly buried cables of this kind in concrete, it is impossible to pull out the cable core from the external protective sheath, and the above requirements cannot be met.

According to the results of the inventor's pursuit of the cause, conventional cables buried directly in concrete are
As shown in FIG. 1, a cable core 2 consisting of a plurality of insulated wire cores 1, 1 twisted together is covered with an external protective sheath 3 such as rubber or plastic in a cylindrical shape. The gap formed along the twist of the wire cores 1, 1 between the sheath 3 and the sheath 3 is filled with inclusions 4,
The inclusions 4 were embedded along the twists of the wire cores 1, 1 and integrated, and were densely packed in order to finish the outer protective sheath 3 in a circular shape.

For this reason, when an attempt is made to pull out the cable core 2, the inclusions 4 are also subject to being pulled out, and as a result, the inclusions 4, which are densely packed inside the outer protective sheath 3, prevent the cable core 2 from being pulled out. It has been found.

Regarding cables directly buried in concrete,
For the purpose of making it easier to expose the cable core by stripping the external protective sheath at the terminal, and to alleviate the tension and bending force received when concrete hardens or cracks, etc. It has been proposed to provide a release agent layer, but even the presence of such a release agent layer cannot contribute to the extraction of the cable core from the outer protective sheath.

In fact, an attempt was made to pull out the cable core together with the inclusions after embedding the directly buried cable in concrete with such a release agent layer, but this attempt ended in failure.

This is probably due to the fact that the thickness of the mold release agent layer was so small that the inclusions and cable core could not move, and were bent and buried in the concrete.

In view of the current situation of conventional direct buried cables of this type in concrete, the present invention has been developed to allow easy removal of the cable core from the external protective sheath that is embedded and integrated in concrete. The purpose is to provide a completely new direct-buried concrete cable that enables rewiring of the same cable.

[Summary of the idea]

The concrete-buried cable of the present invention has a cable between an external protective sheath with a smooth inner surface and a cable core with a longitudinally smooth outer surface.
It is assumed that the cable core is housed in a sponge-structured inclusion divided along the length direction with the cable core sandwiched between the divided surfaces.

According to the direct-buried concrete cable of the present invention having the above-described structure, by pulling out the inclusions divided along the length direction from the terminals of each divided part, the inclusions are formed on the smooth inner surface of the external protective sheath. Similarly, the inclusion peels off from the smooth outer surface of the cable core and deforms into thin pieces due to its own spongy structure, forming a gap between the cable core and the external protective sheath, and the inclusion becomes a divided part due to the gap. In the presence of the increasingly large air gap, the cable core can be pulled out with its own longitudinally smooth surface facing the inner smooth surface of the outer protective sheath. There is.

〔Example〕

FIGS. 2 and 3 show an embodiment of a directly buried cable in concrete according to the present invention, in which two insulated wire cores 11, 11 are arranged in parallel to form a cable core 10.

Therefore, the cable core 10 is made smooth in the length direction by extending the parallel insulated wire cores 11, 11 while remaining parallel in the length direction, and the inner surface of the outer protective sheath 30 is made smooth in the same way as above. It is formed smoothly.

Therefore, the inclusion 40 is provided between the outer protective sheath 30 and the cable core 10 in a filled state.
consists of half-split bodies 41, 41 of a spongy structure made of rubber-like foam etc. divided along the length direction, and the cable core 10 is parallel to the divided surfaces of the divided bodies 41, 41. Insulated wire core 11,
11 is sandwiched and embedded in the external protective sheath 30.

According to the concrete directly buried cable of the present invention constructed as described above, at the cable terminal, as shown in FIG.
By pinching and pulling out each of 1 and 41, the divided bodies 41 and 4 having a spongy structure are obtained.
1 itself deforms in such a way that it becomes thinner in the width direction and extends in the length direction as shown in 41', 41', thereby creating a gap 50 between the outer protective sheath 30 and the cable core 10. , 50 are positively formed, and the divided bodies 41, 41 as inclusions serve as the cable core 10 for each of the insulated wire cores 1.
1 , 11 and the inner smooth surface of the outer protective sheath 30 , thus eliminating inclusions 40 within the outer protective sheath 30 , thereby further Cable core 1 with a large gap
0 can be easily pulled along the inner smooth surface of the outer protective sheath 30 due to its longitudinal smooth surface.

In this embodiment, since the cable core 10 includes a plurality of insulated wire cores 11, 11 provided separately, each insulated wire core can be pulled out one by one in sequence.

Fig. 4 shows a modification of the cable core adopted for the concrete buried cable according to the present invention, in which a plurality of insulated wire cores 11', 11' are arranged in parallel in the length direction. It consists of a vinyl insulated vinyl sheathed flat cable 10' having a flat sheath 12 formed around it, and a flat surface 12a extending in the length direction of the flat sheath 12 is a smooth surface.

[Effects of the invention] As is clear from the above explanation, according to the cable directly buried in concrete according to the invention, the cable core is formed by using a sponge structure as an inclusion provided in a filled state between the cable core and the external protective sheath. The cable core is split from the sandwiching position, and each split portion is individually deformed into long and thin pieces, thereby forming a gap between the outer protective sheath and the cable core while maintaining a smooth surface in the longitudinal direction of the cable core and the outer protection. It can be pulled along the internal smooth surface of the sheath,
Then, with no inclusions and a large gap in the outer protective sheath, the cable core is moved along its length along the smooth surface of the outer protective sheath. It can be easily pulled out.

Therefore, a new wiring material that is to be rewired is connected to the cable core that can be easily pulled out as described above, and the cable core is pulled out as a lead member and the new wiring material that is to be rewired is removed. This allows the wiring material to be drawn into the external protective sheath.

According to this, the wire can be routed much more smoothly and efficiently than the process of pushing the wire into the conduit, and since it can be routed as a solid cable without using a conduit, bends can be reduced. It is easy to install and can be made compact. Etc., the intended purpose of providing a directly buried cable in concrete that can easily be rewired by pulling out the cable core can be fully achieved, and the economic effect can also be extremely large.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram showing an example of the structure of a conventional cable buried directly in concrete, and FIGS. 2 and 3 are explanatory cross-sectional diagrams and longitudinal cross-sectional diagrams showing an example of the structure of a cable directly buried in concrete according to the present invention. 4 are perspective explanatory views showing a modified example of the cable core applied to the cable directly buried in concrete according to the present invention. In the figure, 10, 10' are cable cores, 11,
11' is an insulated wire core, 12 is a flat sheath, 12a is a flat surface, 30 is an external protective sheath, 40 is an inclusion,
41 is a divided body of the inclusion, 41' is a divided body deformed into an elongated shape, and 50 is a void.

Claims (1)

[Scope of utility model registration request] Between the outer protective sheath, which has a smooth inner surface, and the cable core, which has a longitudinally smooth outer surface, there is an inclusion that has a spongy structure divided along the length. A directly buried cable in concrete, characterized in that the cable core is sandwiched between the cable cores.