JP2018010197A - Cable for direct embedding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable for direct embedding, capable of reducing a waste amount of a second sheath, in cable construction.SOLUTION: A cable 1 for direct embedding comprises: an inside cable core 20 covered with a first sheath (inner sheath); and an outside second sheath (reinforcement type coating 10). The second sheath is loosely fitted to the first sheath. The cable core is longer than the second sheath. Preferably, the cable core has a protrusion core part 25 which protrudes from any or both of ends of the second sheath. The second sheath containing the protrusion core part and the cable core is wound to a trunk of a winding bobbin.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cable for direct embedding, and more specifically, includes an inner cable core covered with a first sheath and an outer second sheath, and the second sheath is loosely fitted to the first sheath. It relates to the cable for burial.

  In Japan, efforts are being made to eliminate the use of utility poles from the viewpoints of improving road disaster prevention, securing safe and comfortable traffic spaces, creating good landscapes and promoting tourism. Currently, a method of laying electric wires in underground pipes (also referred to as an electric wire co-groove method) is most often used for this effort to eliminate electric poles. However, this method is difficult to embed pipes on roads with narrow sidewalks or roads without sidewalks, and the application cost is limited due to high equipment costs.

One of the methods to solve the difficulty of burial of pipes and the increase in equipment costs in these undergrounding methods is the method of burying wires directly in the soil (especially because lower costs can be expected) The application of the direct burial method is also being considered.
However, when a communication cable is directly buried in the soil, there is a concern that the cable may be damaged or bent due to cable compression due to earth pressure, thereby adversely affecting the transmission characteristics and mechanical characteristics of the cable.

  For example, Patent Document 1 discloses a direct-embedded optical fiber cable in which an outer sheath formed by winding a high-hardness / high-rigidity plastic tape on a core cable and integrated with an outer sheath on the outer sheath is disclosed. Has been.

JP-A-7-33478

  However, the optical fiber cable described in Patent Document 1 is reinforced with a high-hardness plastic tape to withstand earth pressure, and the cable core is tightly fixed to the exterior. There was a problem that it was difficult to repair and maintain. That is, when repairing and maintaining the optical cable core, it is necessary to bury the entire cable after digging up a range corresponding to the entire length of the cable, and thus it may take a great deal of time and money to recover.

Also, when replacing only the repaired part with a new optical cable core, after digging up the range, install a new closure, etc., and the optical fiber of the optical cable core that does not require repair and the optical fiber of the new optical cable core Are all connected, making recovery in a short time difficult. The communication service is stopped until it is restored, so there is a high possibility that it will not be allowed by the user.
In addition, there is a method of laying a hard duct and then laying an optical fiber cable in the duct, but in that case, the duct and the optical fiber cable are separately laid, and the laying man-hour is almost 2 Double.

  Therefore, it is conceivable that the optical cable core is kept loose with respect to the exterior so that repair and maintenance can be completed in a short time, and the optical cable core is easily pulled out and inserted from the exterior. When laying an optical fiber cable having such a configuration, it is necessary to draw an optical cable core into a manhole or handhole. However, if the exterior is cut off at the time of laying, the cut-out exterior must be discarded on site. In this case, there is a problem that the amount of waste increases at the time of laying, and the labor for waste disposal also increases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a direct burying cable that can reduce the amount of outer packaging discarded when laying a cable.

  A direct embedment cable according to an aspect of the present invention includes an inner cable core covered with a first sheath and an outer second sheath, and the second sheath is loosely fitted to the first sheath. It is a direct embedment cable, and the cable core is formed longer than the second sheath.

  According to the above, it is possible to provide a direct burying cable that can reduce the amount of waste during laying and can reduce labor and man-hours due to waste disposal.

It is a perspective view which shows an example of the cable for direct embedment concerning one embodiment of the present invention. It is a front view of the cable for direct burial. It is a figure which shows the state which pulled out the cable for direct embedment of Example 1. It is a figure which shows the state by which the cable for direct burying was wound around the winding bobbin. It is a figure which shows the cable for direct embed | buried. It is a figure which shows the cable for direct laying laid. It is a figure which shows the state which pulled out the cable for direct embedment of Example 2.

[Description of Embodiment of the Present Invention]
First, the contents of the embodiment of the present invention will be listed and described.
A direct embedment cable according to an aspect of the present invention includes (1) an inner cable core covered with a first sheath and an outer second sheath, and the second sheath is loosely fitted to the first sheath. In this case, the cable core is formed longer than the second sheath. Since the cable core is formed longer than the second sheath, the cable core can be used for connection work in a manhole or the like with the extra length, and the second sheath becomes less prone. Therefore, since it is not necessary to cut off the second sheath from the cable, it is possible to reduce the amount of waste at the time of laying, and to provide a direct burying cable that does not increase the labor involved in waste disposal.

(2) The cable core has a protruding core portion protruding from one or both ends of the second sheath, and the second sheath including the protruding core portion and the cable core is a winding bobbin. It is wound around the torso. If the protruding core portion and the second sheath are accommodated in the take-up bobbin, the cable having the cable core for the extra length can be laid by being drawn out as it is, and it is easy to store and carry on the laying site.
(3) The protruding core portion is wound around the body portion of the winding bobbin prior to the second sheath including the cable core. Since the protruding core portion is wound on the winding start side, for example, the cable core on the winding start side and the second sheath are not fixed, and the cable core and the second sheath on the end portion on the winding end side can be fixed and fed out. .
(4) The winding bobbin has a separate portion that divides the body portion into a region for winding the protruding core portion and a region for winding the second sheath including the cable core, and the protruding core The protruding core portion is wound around a region where the portion is wound. Since the protruding core portion and the second sheath are separately wound up and the second sheath is overlapped and wound around the protruding core portion, the protruding core portion is not pressed from the second sheath. The core part can be easily protected.

[Details of the embodiment of the present invention]
Hereinafter, a specific example of a direct burying cable according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of a direct burying cable according to an embodiment of the present invention, and FIG. 2 is a front view of the direct burying cable.
The direct burying cable 1 includes an optical cable core 20 and a reinforced outer jacket 10 disposed outside the optical cable core 20. The optical cable core 20 corresponds to the cable core of the present invention.

  Although details of the optical cable core 20 are not shown, the optical cable core 20 has a core portion 21 of about 8 cores such as a drop cable for dropping a subscriber. The periphery of the core portion 21 is covered with an inner sheath 22 made of, for example, PE (polyethylene), PVC (polyvinyl chloride), or the like. The inner sheath 22 corresponds to the first sheath of the present invention.

The optical cable core 20 (inner sheath 22) has an outer diameter of about 4 mm to 20 mm, and the optical cable core 20 is formed in a round shape, for example.
The core portion 21 is a cable in which the outer side of a cable (for example, up to about 200 cores) bundled with multi-fiber optical fiber ribbons or the like, such as a low-comfort cable for a branch line, is held with a press-wound tape or the like. There may be.
The core portion 21 may be a slot cable or a slotless cable, and the shape thereof is not limited as long as it is a multi-core optical fiber cable.

The reinforced jacket 10 is loosely fitted to the optical cable core 20 and covers the periphery of the optical cable core 20 to protect the optical cable core 20. The reinforced outer jacket 10 corresponds to the second sheath of the present invention.
The reinforced outer jacket 10 is made of hard plastic such as high density polyethylene (HDPE). If the reinforced casing 10 is made of HDPE, that is, polyethylene having a density of 0.942 (g / cm ³ ) or more, it can sufficiently withstand the compressive force and bending force applied to the cable due to earth pressure.

Further, the reinforced jacket 10 may be a metal such as iron or SUS. If the reinforced casing 10 is made of metal, it can sufficiently withstand the compressive force and bending force applied to the cable due to earth pressure, as described above, but in consideration of handleability, hard plastic is preferred.
Alternatively, the reinforced outer jacket 10 may be formed of a hard plastic whose main material is polypropylene (PP). If the reinforced casing 10 is made of PP, the required strength can be maintained even if the allowable wall thickness is small compared to the case of forming it with HDPE.

  Further, the reinforced outer jacket 10 is formed in, for example, a bellows shape, and a longitudinal section thereof is formed in a waveform. Specifically, the reinforced outer jacket 10 has ridges 11 and valleys 12 formed along a direction orthogonal to the longitudinal direction, and these ridges 11 and valleys 12 are alternately provided along the longitudinal direction of the cable. It has been. In addition, the inner diameter of the reinforced outer jacket 10 (the valley portion 12) is configured to be about 30 mm, and the reinforced outer jacket 10 is also formed in a round shape, for example.

  As described above, the inner sheath 22 of the optical cable core 20 is loose with respect to the reinforced jacket 10, and the optical cable core 20 is easily pulled out of the reinforced jacket 10 when the optical cable core 20 is repaired or maintained. In addition, since the new optical cable core 20 can be easily inserted into the reinforced jacket 10, the optical cable core 20 can be repaired and maintained in a short time.

In addition, if the reinforced jacket 10 is formed into a corrugated shape, it can withstand earth pressure, and the ridges 11 and the valleys 12 formed alternately can provide the same flexibility as a general optical cable. Can be handled easily.
In addition, in the figure, although the example of the bellows-shaped reinforcement | strengthening envelope which the direction of a mountain valley is orthogonal to a longitudinal direction was mentioned and demonstrated, the reinforcement type | mold jacket of this invention is a spiral shape which the direction of a mountain valley intersects with a longitudinal direction. It may be a bellows. It is also possible to form one of the outer peripheral surface and the inner peripheral surface of the reinforced outer jacket flat and make the other corrugated.

  By the way, as described above, the inner sheath 22 of the optical cable core 20 is in a loose state with respect to the reinforced jacket 10, but even with such a structure, the amount of waste is not increased when the cable is laid. It is hoped that. Therefore, the following cables were created.

FIG. 3 is a diagram illustrating a state in which the direct burying cable according to the first embodiment is pulled out, and FIG. 4 is a diagram illustrating a state in which the direct burying cable is wound around the take-up bobbin.
In the direct burying cable 1, the optical cable core 20 covered with the inner sheath 22 is formed longer than the reinforced jacket 10. Specifically, as shown in FIG. 3, the optical cable core 20 has a protruding core portion 25 that extends in the longitudinal direction of the cable and protrudes from the rear end of the reinforced outer jacket 10.

  The length of the projecting core portion 25 is set according to the number of manholes (or handholes, the same shall apply hereinafter) to be laid when the direct burying cable 1 is manufactured. For example, when the cable 1 is laid on both sides of one manhole, if the manhole diameter is about 1 to 2 m, the length of the optical cable core drawn into the manhole needs to be 5 to 6 m. For example, the length is set to about 5 to 6 m. That is, the optical cable core 20 is manufactured to be about 5 to 6 m longer than the reinforced jacket 10, and the manufactured cable 1 is wound around, for example, a winding bobbin.

  As shown in FIG. 4, the take-up bobbin 30 has, for example, a resin body 31, and both ends of the body 31 are provided with, for example, resin flanges 33. The flange portion 33 is configured to be connectable to a drive unit (not shown) of the winding device, and the bobbin 30 is rotatable about its axis (shown in the z direction in FIG. 4). When the bobbin 30 is rotated in a predetermined direction by the driving force from the winding device, the cable 1 is wound on the trunk portion 31 along the circumferential direction of the bobbin 30.

A separate part 32 is erected on the body part 31 shown in FIG. The separate part 32 can divide the trunk | drum 31 into the area | region 31a which winds up the protrusion core part 25 in the axial direction, and the area | region 31b which winds up the reinforcement type | mold outer jacket 10 which contains the optical cable core 20 inside.
And in the cable 1 of Example 1, the protruding core part 25 is wound around the area | region 31a of the trunk | drum 31 ahead of the reinforcement | strengthening type | mold jacket 10, and after the winding-up of this protruding core part 25 is complete | finished, reinforcement | strengthening The mold jacket 10 is wound around the region 31 b of the body portion 31. The separate portion 32 may be provided with, for example, a through hole or a groove (not shown) that allows the protruding core portion 25 to pass therethrough. Moreover, the separate part 32 may be provided in the axial direction outer side of either of the collar parts 33. FIG.

In this embodiment, the example in which the body portion 31 is divided into the two regions 31a and 31b has been described. However, the optical fiber core is formed after the projecting core portion 25 is wound on the body portion 31 without being divided into two regions. The reinforcing outer cover 10 including 20 inside may be wound around the protruding core portion 25.
In addition, when the length of the cable is short, it is possible to carry it in a bundled state without being wound around the bobbin.

FIG. 5 is a diagram showing a direct burying cable, and FIG. 6 is a diagram showing a laid direct burying cable. In order to clarify the optical cable core 20 in the reinforced jacket 10, FIG. 6 shows the optical cable core 20 so that the optical cable core 20 can be seen even when it is arranged inside the reinforced jacket 10.
In this example, the cable 1 is laid between the manholes 55a and 55c, but it is assumed that there is one manhole 55b between the manholes 55a and 55c.
Since one manhole is taken into consideration, when the distance between adjacent manholes 55a and 55b and between the manholes 55b and 55c is 70 m, if the length of the protruding core portion 25 is set to 5 m, for example, The reinforced outer jacket 10 is manufactured at 140 m (= 70 × 2) and the optical cable core 20 is manufactured at 145 m (= 140 + 5), and is wound around the bobbin 30 described with reference to FIG.
In consideration of paying out the cable 1 from the bobbin 30, when winding on the bobbin 30, at least at the end of winding, the inner peripheral surface of the reinforced outer jacket 10 and the outer peripheral surface of the optical cable core 20 are fixed. Preferably it is. Similarly, the winding start end may be lightly adhered between the inner peripheral surface of the reinforced outer jacket 10 and the outer peripheral surface of the optical cable core 20.

When the bobbin 30 is carried to the site where the cable 1 is laid, and the tip (also referred to as a pulling end) of the reinforced outer jacket 10 is gripped and pulled out from the bobbin 30, the cable 1 described in FIG.
The cable 1 is placed on the manhole 55b to be laid, and the reinforced outer jacket 10 is cut using a tool such as a cutter, for example, and the first reinforced outer jacket 10a embedded between the manholes 55a and 55b And the second reinforced outer jacket 10b embedded between the manholes 55b and 55c.

Next, as shown in FIG. 5, the first reinforced outer jacket 10a is disposed between the manholes 55a and 55b. For example, the second reinforced outer jacket 10b is shifted rearward along the optical cable core 20 to shift the manhole 55b. , 55c and if the optical cable core 20 is pulled out from between the cut first reinforced outer cover 10a and the second reinforced outer cover 10b, it protrudes from the rear end of the reinforced outer cover 10 The optical cable core 20 corresponding to the protruding core portion 25 appears between the first reinforced outer jacket 10a and the second reinforced outer jacket 10b. The optical cable core corresponding to the protruding core portion 25 that appears is disposed in the manhole 55b.
The optical cable core 20 may be pulled out without removing the reinforced outer jacket 10 at the portion corresponding to the manhole and without shifting the position of the second reinforced outer jacket 10b.

  Subsequently, the soil between the manholes 55a and 55b and the surrounding soil between the manholes 55b and 55c is dug, and the first reinforced outer jacket 10a and the second reinforced outer jacket 10b including the optical cable core 20 are dug. Install in each. At that time, for example, the first reinforced type jacket 10a and the second reinforced type jacket 10b are contracted along the longitudinal direction of the cable so as to match the length between the manholes 55a and 55b and between the manholes 55b and 55c, respectively. I will. Thereafter, the excavated soil is returned and the first reinforced outer covering 10a and the second reinforced outer covering 10b are filled (also referred to as covering soil).

As shown in FIG. 6, the optical fiber of the newly installed optical cable core 20 and the optical fiber of the existing optical cable core 50 are connected using the closure 45a in the manhole 55a and the closure 45c in the manhole 55c, respectively.
In the manhole 55b, the optical fibers of the newly installed optical cable core 20 are connected to each other using the closure 45b.

As described above, since the optical cable core 20 is formed longer than the reinforced jacket 10, it can be used for connecting work such as a manhole by using this as an extra length, and the reinforced jacket 10 is less likely to be excessive. Therefore, since it is not necessary to cut off the reinforced outer jacket 10 from the cable, the amount of waste at the time of laying can be reduced, and the labor for waste disposal does not increase.
In the above example, it is assumed that there is one manhole 55b between the manholes 55a and 55c. However, when there are two manholes between the manholes 55a and 55c, the distance between the manholes is 70 m. If the length of the cable core required for the connection work is 5 m, the length of the protruding core portion 25 is required to be 10 m, the reinforced jacket 10 is increased by 70 m and manufactured to 210 m, and the optical cable core 20 is increased by 75 m to 220 m. And is wound around the bobbin 30.

FIG. 7 is a diagram illustrating a state in which the direct burying cable according to the second embodiment is pulled out.
In the first embodiment, an example in which the protruding core portion 25 protrudes only from the rear end of the reinforced outer jacket 10 has been described. However, as shown in FIG. 7, the protruding core portion 25 may protrude from both the front end and the rear end of the reinforced outer jacket 10. If comprised in this way, the extra length of the cable required for the connection in a manhole can be drawn in from both ends.
Although not shown, the protruding core portion can be protruded only from the tip of the reinforced outer jacket 10.

  In addition, although the case where this invention was applied to the optical cable core was demonstrated as embodiment, a metal cable core may be sufficient instead of an optical cable core.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Direct embedment cable, 10 ... Reinforced outer cover, 10a ... First strengthened outer cover, 10b ... Second strengthened outer cover, 11 ... Mountain part, 12 ... Valley part, 13 ... Opening end part, DESCRIPTION OF SYMBOLS 20 ... Optical cable core, 21 ... Core part, 22 ... Inner sheath, 25 ... Protruding core part, 30 ... Bobbin, 31 ... Trunk part, 31a, 31b ... Area | region, 32 ... Separate part, 33 ... Gutter part, 45a, 45b, 45c ... closure, 50 ... existing optical cable core, 55a, 55b, 55c ... manhole.

Claims (4)

A direct embedment cable comprising an inner cable core covered with a first sheath and an outer second sheath, wherein the second sheath is loosely fitted to the first sheath;
A direct embedment cable in which the cable core is formed longer than the second sheath. The cable core has a protruding core portion protruding from either or both ends of the second sheath,
The cable for direct embedding according to claim 1, wherein the second sheath including the protruding core portion and the cable core is wound around a trunk portion of a winding bobbin.   The cable for direct embedment according to claim 2, wherein the protruding core portion is wound around the trunk portion of the take-up bobbin prior to the second sheath including the cable core. The winding bobbin has a separate portion that divides the body portion into a region for winding the protruding core portion and a region for winding the second sheath including the cable core, and winds the protruding core portion. The cable for direct burying according to claim 3, wherein the protruding core portion is wound around a region to be taken.

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