JPH0921918A - Sealing structure of connecting terminal box for optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce a cost without increasing materials to be carried to site and degrading workability by eliminating the need for setting different nuts and packings corresponding to the diameters of optical fiber cables. SOLUTION: This sealing structure has a terminal box body 25 in which the optical junctions 24 of the optical fiber cables 23 led out of the optical fiber cables 22 inserted therein via apertures 21 are internally installed, the protective packings 29 which enclose the apertures 21 and cover the front end faces 27 of cable housing sleeves 26 extending outward from the outside surfaces 34 of the terminal box body 25 and shrunk tubes 30 which water-tightly cover the regions from the cable housing sleeves 26 to the parts of the optical fiber cables 22 exposed from the cable housing sleeves 26. At least both ends 30a in the axial direction of the shrunk tubes 30 are respectively water-tightly brought into contact with the outer peripheral surfaces 28 of the cable housing sleeves 36 or the optical fiber cables 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure for an optical fiber cable connection terminal box for accommodating an optical connection portion of an optical fiber cable.

[0002]

2. Description of the Related Art In order to branch and connect an optical fiber cable to an optical fiber core through an optical connector or a fusion splicer, an optical fiber cable for accommodating the optical connector and the extra connection length thereof A connection terminal box is used.

Conventionally, the optical fiber cable connection terminal box is mainly formed of a terminal box body 2 installed in the middle of the wiring section of a plurality of aerial optical fiber cables 1 as shown in FIG. 3, for example. There is a terminal box body 2 in which an optical connecting portion 3 for connecting optical fibers derived from the overhead optical fiber cable 1 is housed. The terminal box body 2 is a box body in which the entire body except the insertion hole 4 into which the overhead optical fiber cable 1 is inserted is watertightly formed of metal, resin or the like. Inside the terminal box body 2, a retractor 5 for retaining the aerial optical fiber cable 1 inserted therein is provided near the insertion hole 4. The insertion hole 4 is
A nut 6 mounted on the aerial optical fiber cable 1 inserted through the insertion hole 4 is screwed. The nut 6 is watertightly sealed between the inner surface of the through hole and the outer surface of the overhead optical fiber cable 1 by a packing (not shown) provided on the inner surface of a through hole (not shown) passing through the center. The retractor 5 has a structure in which the outer core 7 of the aerial optical fiber cable 1 inserted into the terminal box body 2 is removed and the exposed slot core 8 is clamped between the slot core 8 and the inner wall 9 of the terminal box body 2. Has become. A tension member fixing tool 11 for fixing the tension member 10 of the aerial optical fiber cable 1 is attached on the axially inner side of the insertion hole 4 with respect to the pulling tool 5. At the central portion of the terminal box body 2, the optical connecting portion 3 and the extra connection length 1 thereof are provided.
A plurality of trays 13 for storing 2 are stored in a stacked state. The upper part of the terminal box body 2 (Fig. 3
In the upper part, a suspending portion 15 for suspending the terminal box main body 2 is provided in a protruding manner on a support wire 14 arranged in parallel with the overhead optical fiber cable 1. A hinge 16 that rotatably supports a lid (not shown) that opens and closes the terminal box body 2 is provided below the terminal box body 2.

[0004]

In view of the weakness of the optical fiber and the optical connection portion 3 to water, the optical fiber cable connection terminal box is required to have a high water blocking property. In the case of a terminal box, a nut 6 having a shape suitable for the diameter of the overhead optical fiber cable 1,
The inner surface of the through hole of the nut 6 and the overhead optical fiber cable 1
It is necessary to select a packing that matches the shape of the outer surface of the terminal box to prevent rainwater and the like from entering the terminal box body 2, which causes a problem of inefficient installation work. Here, since it is necessary to prepare different sets of nuts and packings corresponding to the diameters of the optical fiber cables, the amount of materials to be carried into the site is increased, the workability is reduced, and the cost is increased. In addition, the end of the packing is exposed to the outside of the terminal box main body 2 and the packing is deformed when the aerial optical fiber cable 1 is swung by wind or the like, which easily causes pain and has a problem that the maintenance cycle is short.

The present invention has been made in view of the above-mentioned problems, and improves the work efficiency of installation of the connection terminal box for optical fiber cables and extends the maintenance cycle. It is intended to provide.

[0006]

According to a first aspect of the present invention, there is provided a seal structure for a connection terminal box for an optical fiber cable, wherein the optical fiber cable is inserted into the inside through an opening formed in a wall, and the optical fiber cable is inserted. From the cable housing sleeve of the optical fiber cable, from the terminal box body that internally houses the optical connection portion of the optical fibers derived from the above, and the cable housing sleeve that projects outward from the outer surface of the wall portion to surround the opening. A shrinkable tube that covers the exposed area from the outside and is watertightly covered, and at least both axial ends of the shrinkable tube are watertight to the outer peripheral surface of the cable storage sleeve or the optical fiber cable, respectively. The close contact was taken as a means for solving the above problems.

According to a second aspect of the present invention, there is provided a seal structure for an optical fiber cable connection terminal box, wherein the protective packing is in contact with the tip end surface of the cable storage sleeve. That is, the outer peripheral surface of the optical fiber cable is covered with a waterproof tape, and the protective packing is sandwiched between the waterproof tape and the front end surface.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a seal structure for a connection terminal box for an optical fiber cable according to the present invention will be described below with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the seal structure of the connection terminal box for an optical fiber cable according to the present embodiment has an overhead optical fiber cable 22 having a circular cross section inside through an opening 21 formed in a wall 20. Terminal box main body 25 in which an optical connection portion 24 of optical fibers 23 led out from the overhead optical fiber cable 22 is inserted.
And a tip end surface 2 of the tip of the cable storage sleeve 26 protruding outward from the outer surface of the wall 20 surrounding the opening 21.
7, a protective packing 29 which is installed in contact with the outer peripheral surface 28 of the aerial optical fiber cable 22 and is detachably attached to the outer peripheral surface 28.
And a contraction tube 30 that covers the region from the cable storage sleeve 26 to the exposed portion of the overhead optical fiber cable 22 from the cable storage sleeve 26 from the outside to be watertight, and at least the axis of the contraction tube 30. Both end portions 30a in the direction are watertightly adhered to the cable housing sleeve 26 or the outer peripheral surface 28 of the aerial optical fiber cable 22, respectively, and the outer peripheral surface 28 of the aerial optical fiber cable 22 is covered with a waterproof tape 31 to provide the waterproof tape. The protective packing 29 is sandwiched between 31 and the front end surface 27 of the cable storage sleeve 26.

The illustrated terminal box main body 25 is interposed between the installation sections of the three aerial optical fiber cables 22 arranged in parallel with each other, and the terminal box body 25 is provided with a suspending tool 32 projecting from the upper portion of the terminal box body 25. In parallel with the overhead optical fiber cables 22 of the book, the overhead optical fiber cables 22 are suspended from a support wire 33 disposed at the top of the overhead optical fiber cables 22. This terminal box body 25
Is a rectangular parallelepiped box, and has an end face 34 (outer surface of the wall portion) perpendicular to the axes of the three overhead optical fiber cables 22. The end surface 34 has the opening 21
3 are opened. These openings 21 are opened at positions corresponding to the positions of the arrangement axes of the three overhead optical fiber cables 22. The end surface 34 of the terminal box body 25
The cable storage sleeve 26 is projectingly provided on the. The inner surface of the cable storage sleeve 26 has an opening 2
It has a circular cross-section that matches the inner surface of 1. Each of these cable storage sleeves 26 has a protruding amount from the end face 34 of several tens of millimeters, and has an inner diameter that can accommodate the largest of various diameters of the overhead optical fiber cable 22 to be installed. doing. In the figure, only one of the three overhead optical fiber cables 22 has a larger diameter than the other, but the three openings 21 and the three cable storage sleeves 26 have the same inner diameter. Has become. The inner diameters of the opening 21 and the three cable storage sleeves 26 are equal to each other.
The sizes may be different from each other in accordance with the outer diameter of the two.

In the vicinity of the opening 21 inside the terminal box body 25, an aerial optical fiber cable 22 is provided with an outer cover 35.
The pressing force is applied from the outside of the wall 20 of the terminal box body 25.
A clamp tool 36 for clamping is provided between and. On the axis of the overhead optical fiber cable 22 clamped by the clamp tool 36 and further inward of the clamp tool 36 of the terminal box body 25, the tension member 37 that fixes the tension member 37 led out from the overhead optical fiber cable 22 is fixed. The member fixing tool 38 is provided apart from the clamp tool 36. At the center of the terminal box body 25,
In the terminal box body 25, the overhead optical fiber cable 22
A plurality of trays 39 for accommodating the optical connection portions 24 of the optical fibers 23 and the extra connection lengths derived from the above are accommodated in a stacked state. The tray 39 shown in FIG.
As a result, the fusion splicing portion is stored. The optical connector 24 housed in the tray 39 may be another optical component such as an optical connector.

An insertion groove 40 for inserting the protection packing 29 is formed on the inner surface of the outer end of the cable storage sleeve 26. The protective packing 29 is made of a material having water impermeability and elasticity to some extent.
It is a shaped member and is attachable to and detachable from the overhead optical fiber cable 22. On the end surface of the protective packing 29 on the one side in the axial direction, an insertion flange 41 to be inserted into the insertion groove 40 is provided in a protruding manner. The protective packing 29 attached to the outer end of the cable storage sleeve 26 has an inner peripheral surface 41 on the outer peripheral surface 28 of the aerial optical fiber cable 22 to be installed.
By contacting at a, the aerial optical fiber cable 22 is positioned concentrically with the cable housing sleeve 26. The outer peripheral surface 42 of the protective packing 29 is
When attached to the outer end of the cable storage sleeve 26, it is shaped so as to form a continuous surface with the outer peripheral surface 26a of the cable storage sleeve 26.

The waterproof tape 31 is in contact with the axially outer end surface of the protective packing 29. The waterproof tape 31 is a butyl rubber self-adhesive tape,
At the work site, after the relative position between the terminal box body 25 and the overhead optical fiber cable 22 is determined, the worker mounts it on the outer peripheral surface 28 of the overhead optical fiber cable 22.

The shrink tube 30 is made of a material having a high flexibility at room temperature, such as ethylene / propylene rubber, and has a thickness of 1.5 to 2.0 mm and a cross-sectional shape smaller than that of the aerial optical fiber cable 22. It is said that. The shrinkable tube 30 corresponds to the cable storage sleeve 26.
The protective packing 29, the waterproof tape 31, and the aerial optical fiber cable 22 inserted into the cable storage sleeve 26 are covered from the outside, and the inner surface 43 is the outer circumference of each of the cable storage sleeve 26, the protective packing 29, and the waterproof tape 31. The surfaces 26a, 42, 31a and a part of the outer peripheral surface 28 of the overhead optical fiber cable 22 are in close contact with each other.
Since both ends 30a in the axial direction of the shrinkable tube 30 are reduced in diameter as compared with the central part, the inner surface 43 of the both ends 30a in the axial direction is contracted by itself, so that the overhead optical fiber cable 22
The outer peripheral surface 28 exposed from the cable housing sleeve 26 and the outer peripheral surface 26a of the contracting sleeve 26 are watertightly fixed. The aerial optical fiber cable 2 in the portion between the both ends 30a in the axial direction of the contraction tube 30.
2 Between the axial end 30a fixed to the outer peripheral surface 28 and the mounting position of the waterproof tape 31, the overhead optical fiber cable 2
A clearance is formed between the flexible optical fiber cable 22 and the flexible optical fiber cable 22 so that the flexible optical fiber cable 22 can be deformed in accordance with the displacement or deformation of the aerial optical fiber cable 22. It is not necessary to use a jig or the like to cover the cable storage sleeve 26, the protective packing 29, the waterproof tape 31, and the aerial optical fiber cable 22 with the shrinkable tube 30, and the work is simple.

The operation and effect of the present invention will be described below. The sealing structure of the optical fiber cable connection terminal box is adapted according to the cross-sectional diameter dimension of the aerial optical fiber cable 22 when the aerial optical fiber cable 22 having an arbitrary cross-sectional diameter is inserted into and supported by the opening 21. By simply selecting the protective packing 29 having the thickness and inner diameter of the insertion flange 41, other parts can be used without modification, and the installation work efficiency is improved. That is, the shrinkable tube 30 can cope with various diameters of the aerial optical fiber cable 22 inserted into the cable storage sleeve 26 by adjusting the shrinkability of the shrinkable tube 30 itself, and the waterproof tape 31 can be adjusted by adjusting the mounting length. The overhead optical fiber cable 22 can be positioned coaxially with the cable storage sleeve 26 by selecting only the protective packing 29. At this time, the protective packing 29 stops the clearance between the outer peripheral surface 28 of the aerial optical fiber cable 22 and the inner surface of the cable housing sleeve 26, and prevents rainwater and the like from entering the terminal box body 25.

The seal structure of the connection terminal box for the optical fiber cable has a contraction tube 30 when the overhead optical fiber cable 22 is swung by wind or the like and the portion exposed from the cable storage sleeve 26 is curved. The flexible part 44
Since it is appropriately deformed, the watertightness between its both ends 30a is always maintained, and it is possible to reliably prevent the intrusion of rainwater or the like into the terminal box body 25. The shrinkable tube 30 is
Since it is excellent in flexibility, it has a long life against repeated deformation and can waterproof the terminal box body 25 for a long period of time. In addition, the shrinkable tube 30 has a protective packing 29.
Since the waterproof tape 31 and the waterproof tape 31 are protected from being exposed, deterioration of the protective packing 29 and the waterproof tape 31 is suppressed, and the maintenance cycle is significantly extended. Further, since the protective packing 29 is sandwiched between the waterproof tape 31 mounted on the overhead optical fiber cable 22 and the distal end surface 27 of the cable storage sleeve 26, an appropriate posture is maintained at an appropriate position. The contact portion of the shrinkable tube 30 with the tip end surface 27 of the cable housing sleeve 26 is protected, and even if the shrinkable tube 30 is deformed in response to rocking of the aerial optical fiber cable 22, it can be used for a long time without being damaged.

The opening 2 formed in the terminal box body 25
1 may be any number other than 3. In the above-mentioned embodiment, the seal structure of the optical fiber cable connection terminal box applied to the aerial optical fiber cable is shown, but it is also applicable to the frame and the optical fiber cable connection terminal box laid in the building. You can

[0017]

As described above, in the sealing structure of the connecting terminal box for optical fiber cables according to the first aspect, the optical fiber cable is inserted into the inside through the opening formed in the wall, and the optical fiber cable is inserted. A terminal box body that internally houses the optical connection between optical fibers derived from the fiber cable, and a cable storage sleeve that projects outward from the outer surface of the wall and surrounds the opening. A shrinkable tube that covers the region exposed from the sleeve from the outside and is watertightly covered, and at least both axial end portions of the shrinkable tube are respectively provided on the outer peripheral surface of the cable storage sleeve or the optical fiber cable. Due to the watertight contact, the optical fiber cable oscillates due to wind, etc., and the part exposed from the cable storage sleeve is bent. Expediently, the shrink tube to maintain the watertight portion housed between its ends appropriately modified,
It is possible to reliably prevent rainwater and the like from entering the terminal box body.

According to a second aspect of the present invention, there is provided a seal structure for a connection terminal box for an optical fiber cable according to the first aspect, wherein a protective packing for protecting the shrinkable tube is provided at a tip of the cable storage sleeve. The protective packing is placed in contact with the surface, the outer peripheral surface of the optical fiber cable is covered with the waterproof tape, and the protective packing is sandwiched between the waterproof tape and the front end surface. Since the posture is maintained, the cable storage sleeve can be stopped more reliably and at the same time,
Since the waterproof tape itself also stops the water inside the shrinkable tube, the reliability of the water stop is improved.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a seal structure for a connection terminal box for an optical fiber cable according to the present invention.

FIG. 2 is a plan sectional view showing a seal structure of the connection terminal box for the optical fiber cable of FIG.

FIG. 3 is a front sectional view showing a conventional seal structure of a connection terminal box for an optical fiber cable of FIG.

[Explanation of reference numerals] 20 ... Wall part, 21 ... Opening part, 22 ... Optical fiber cable, 23 ... Optical fiber, 24 ... Optical connection part, 25 ... Terminal box body, 26 ... Cable storage sleeve, 27 ... Tip surface, 2
8 ... Outer peripheral surface, 30 ... Shrink tube, 30a ... End portion, 31
... Waterproof tape, 34 ... Outer surface (end surface) of the wall portion.

Claims (2)

[Claims] 1. A seal structure for a connection terminal box for an optical fiber cable for accommodating an optical connection part (24) of the optical fiber cable (1), the opening part (21) formed in a wall part (20). ) Through which an optical fiber cable is inserted, and a terminal box main body (25) which internally houses an optical connection part of the optical fibers (23) led out from the optical fiber cable, and an outer surface (34) of the wall part A shrinkable tube (30) that covers the region from the outside of the cable housing sleeve (26) projecting outwardly surrounding the opening to the part exposed from the cable housing sleeve and covers it from the outside in a watertight manner. ) And at least both axial end portions (30a) of the shrink tube are water-tightly sealed to the outer peripheral surface (28) of the cable storage sleeve or the optical fiber cable, respectively. Sealing structure of a connection terminal box making for an optical fiber cable, characterized in that is. 2. The seal structure for a connection terminal box for an optical fiber cable according to claim 1, wherein a protective packing (29) for protecting the shrink tube is placed in contact with the distal end surface (27) of the cable storage sleeve. Then, a waterproof tape (31) is mounted on the outer peripheral surface of the optical fiber cable, and the protective packing is sandwiched between the waterproof tape and the front end surface, thereby sealing the connection terminal box for the optical fiber cable. Construction.