JPS61267009A - Connecting box for optical fiber cable - Google Patents

Abstract

PURPOSE:To improve the reliability of airtight sealing by putting a pressure ring in a sealing means provided to a cable lead-in part, pressing a sealing tape layer and an O ring which seal the gap between a cable and the internal surface of the lead-in opening in the axial direction of the cable with the pressure ring, and bringing them in contact with the cable at any time. CONSTITUTION:A connecting box 10 is provided with a main body 11 whose end wall 11a connects with one end of a peripheral wall 1b having the cable lead-in opening 12 at the opposite position, sealing means 14 and 15 which clamp the sealing tape layer 28 wound around the cable at the cable lead-in opening part made of a lid 13 for sealing the opening part of the main body airtightly with the sealing material in a free opening/closing state and then inserted into the lead-in opening and the O ring 31 fitted around the outer periphery of the cable at both end parts in the axial direction of the cable. Namely, the sealing tape layer 28 and O ring which seal the gap of the cable lead-in opening part are brought into complete contact with the external surface of the cable and the internal surface of the lead-in opening by applying pressure continuously to make the airtightness perfect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a junction box for optical fiber cables, and more particularly to a junction box that has improved airtightness to enhance the protection effect of optical fiber joints.

[Conventional technology]

A well-known optical fiber cable connection section is shown in FIG. This connection part is connected to optical fiber cables A and A.
The stay 2 connects the clips 1 and 1 attached to the sheath end of the stay 2, and the connection part of the tension member (and the connection part of the intervening quad (not shown) are arranged inside the stay 2, and the optical fiber is attached to the outer periphery of the stay. Extra length processing bobbins 3, 3 having a diameter that does not cause an increase in loss are attached, and a holder 4 placed between both bobbins holds the connection part 5 of the core wire 3, and is attached to the core wire on both sides of the connection part. The extra length part 6 is added to the extra length processing sheet 7.
pass it through the slit and wrap it around each bobbin 3 together with the sheet. After that, a protective sleeve that surrounds the bobbin and a cylindrical protective case (none of which are shown) are placed between the sheaths, and the cylindrical protective case is divided into two parts that hold the clip 1, the sealing tape layer 8, and the end of the cylindrical protective case. holders (also not shown) are airtightly attached to both sides of the connection to complete the connection process.

[Problem that the invention seeks to solve]

However, in such a connection, the airtight seal between the two-split holder and the cable and between the holder and the cylindrical protective case was achieved by simply wrapping or fitting a layer of sealing tape. If a pressure difference occurs between the inside and outside of the protective case, or if it is subjected to continuous vibration or heat cycles, outside air, water, etc. are particularly likely to enter the case, resulting in poor reliability in terms of long-term protection of the connections.

Further, since extra length processing bobbins are provided on both sides of the core wire connection portion, the longitudinal dimension becomes large, and connection may not be possible within a small manhole or handhole.

The present invention has been made with the aim of eliminating these problems.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a connection box that houses the entire connection part of an optical fiber cable, which is connected to a main body in which an end wall is connected to one end of a peripheral wall having a cable inlet at an opposing position, and a sealing material. and a lid that airtightly and freely closes the opening of the main body, and a sealing tape layer that is wrapped around the outer circumference of the cable and inserted into the introduction port, and a sealing tape layer that is wrapped around the outer circumference of the cable and inserted into the introduction port, and a sealing tape layer that wraps around the outer circumference of the cable at both ends thereof. A seal means is provided in which the fitted O-ring is tightened by a pressure ring in the cable axial direction I.

That is, by constantly applying pressure to the sealing tape layer and the O-ring that seal the gap in the cable inlet, the sealing tape layer and the O-ring are brought into complete contact with the outer surface of the cable and the inner surface of the inlet, thereby ensuring perfect airtightness. According to this structure, the size of the sealing means provided on both sides of the connection portion can be reduced, so that the longitudinal dimension of the cable in the connection box can be reduced, and connection work in narrow spaces can be facilitated.

Hereinafter, the detailed structure of the present invention will be explained based on the embodiments shown in the accompanying drawings.

[Example] As shown in FIGS. 1 and 2, the exemplary junction box 10 is
A main body 11 consisting of a peripheral wall 11b having an inlet 12 for the cable A at a position facing the end wall 11a, a lid 13 that faces the end wall 11a and closes the opening of the main body, and is provided between the cable inlet and the main body and the lid. Sealing means 14, 1.5. A fixing bolt 16 for the lid, a clamp 17 for fixing a tension member (not shown) of the cable to the end wall, a connecting terminal 18 of the intervening quad q, and a mounting bar 19 whose one end is supported by the end wall 11a.
The connecting portion of the optical fibers A and A is housed inside the main body. The illustrated connecting portion uses an extra length processing card 20 for processing the extra length of the core wire.

The extra length processing card 20, as shown in FIG.
Approximately 6 to 8 slits 23 for introducing the core wire, each of which has an entrance narrowed by a cut 23a, are provided in each of the elastic bodies 22 made of chloroprene rubber, which are fitted in opposing positions, and an end wall 24 connected to one end of the peripheral wall A holder 25 for holding both the connection part 5 and the extra length part 6 of the core wire 3 and a holder 26 for holding only the extra length part 6 are provided on the inner surface of the core wire 3, and a parer 19 is provided on the upper and lower peripheral walls.
It is a tray-shaped thing provided with a notched groove 27 through which the wires a and a are passed, and is loop-wound in advance in the reverse direction from the slit 23 of the connected core wires a and a at a position opposite to the connecting portion 5 toward the connecting portion. The extra lengths 6 of the core wires are stored together as shown in the figure, and inserted and held in the slits of holders 25 and 26, each of which is made of an elastic body. After the same process is applied to all of the stored fibers, at least one of them is stored and fixed in the junction box 10. This connection section is used to increase the number of cards 20 as the number of fibers to be connected increases. The number of cards used can be increased and they can be stacked parallel to each other and connected using the mounting bar 19 as shown in Figure 4, making it easy to deal with excess length.Also, since multiple cards can be taken in and out individually, it is easier to switch connections, etc. Although it is excellent in workability, the connection portions housed in the connection box 10 are not limited to this card type.

Next, the sealing means 14.15 will be described. Reference numeral 15 denotes an O-ring gasket, and approximately one to two threads are interposed between the main body of the box 10 and the lid.

The sealing means 14 may have the structure shown in FIG. 1, but
The one shown in FIG. 6 or FIG. 7 is preferred.

That is, the sealing means 14 in FIG. 1 consists of a sealing tape layer 28 interposed between the sheath of the cable A and the inner surface of the inlet 12 whose actual diameter is small, and a pressure applied to the sealing tape whose flange portion is tightened with bolts 29. It consists of a ring 30 and an O-ring gasket 31 that seals the joint interface between them, and the tightening pressure of the ring 30 is applied only to the insertion part of the sealing tape, whereas the one shown in FIG. 5 introduces a sealing tape layer 28. With the pressure ring 33 screwed into the hole of the holder 32 inserted into the opening 12, the O-ring gasket 31 assembled between the pressure ring 30 and the holder 321 main body 11 is individually moved in the cable axial direction by the ring 30. Tighten it.
The sealing material is kept in close contact with the cable and main body under constant pressure, increasing the reliability of the airtight seal.

In addition, the sealing means shown in FIG. 6 is obtained by press-fitting an annular tapered collar 34 with a longitudinal groove to improve shrinkability into the sealing tape layer 28 with a ring of 3 degrees. The sealing function is further enhanced by constantly applying strong sealing pressure to the main body and cable.

In order to further downsize the box 10 and improve connection workability in narrow spaces, the cable inlet 12 is preferably inclined at a predetermined angle θ with respect to the line connecting the opposing inlets, as shown in the figure. desirable.

- Also, the material of the junction box 10 is preferably a hard plastic or a lightweight metal such as aluminum, but any material may be used as long as it can maintain airtightness.

In addition, the junction box 10 can be provided with a gas alarm 35 and a gas valve 36 as shown in FIG. 1D, if necessary.

〔effect〕

As described above, in the junction box of the present invention, the sealing means provided at the cable inlet includes a pressure ring, and the sealing tape layer seals the gap between the cable and the inner surface of the inlet. Since the O-ring is pressurized in the cable axial direction so that it always adheres well to the cable and the main body, the reliability of the airtight seal is significantly increased.

For example, prepare 10 samples each having the structures shown in FIGS. 5 and 6, and place 1. In the airtightness test where a pressure of OK910f was applied, there was no pressure drop for any sample for 48 hours or more.

Furthermore, the internal pressure of the junction box is reduced to 1. In the heat cycle test maintained at OKti/aJ, it showed resistance of more than 50 cycles,
Furthermore, in a vibration test, no gas leakage occurred even when vibrations were applied 106 times at a frequency of IQHz for an amplitude of +5 and a frequency of IQHz at the same internal pressure.

When using the extra length processing card mentioned in the example, the extra length of the core and the connection part can be efficiently stored in parallel in a narrow space, so the main body can be downsized and connections can be made in narrow spaces. This effect is more pronounced when the cable inlet is inclined as shown in FIG.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing an example of the connection box of the present invention, Fig. 2 is a partially cutaway bottom view thereof, Fig. 3 is a perspective view of an extra length processing card forming the connection part, and Fig. 4 The figure is a perspective view of the assembled state, FIGS. 5 and 6 are cross-sectional views showing modified examples of the sealing means provided at the cable inlet, and FIG. 7 is a front view of an example of a conventional connection part during assembly. It is. Patent applicant Sumitomo Electric Industries, Ltd. Agent Kama 1) Text 2 Figure 1 Figure 2

Claims (4)

[Claims] (1) Consists of a main body with an end wall connected to one end of the peripheral wall with a cable inlet in an opposing position, and a lid that airtightly and freely closes the opening of the main body through a sealing material, allowing light to enter the main body. A junction box that stores the entire connection part of a fiber cable, and pressurizes the cable introduction port with a sealing tape layer that is wrapped around the outer circumference of the cable and inserted into the introduction port, and an O-ring that is fitted around the outer circumference of the cable at both ends of the sealing tape layer. A junction box for an optical fiber cable, characterized in that it is provided with a sealing means configured to be tightened in the axial direction of the cable by a ring. (2) The sealing means includes a holder that surrounds the sealing tape layer from the outside, an O-ring that seals a gap on the outer periphery of the holder, and a second O-ring that presses the outer periphery sealing O-ring on the inlet side of the inlet in the cable axial direction. The optical fiber cable junction box according to claim (1), characterized in that the optical fiber cable junction box is provided with a pressurizing ring. (3) Claim (1) characterized in that the sealing means includes an annular tapered tab that is press-fitted into the sealing tape layer by the pressing force of a pressure ring.
Junction box for optical fiber cables as described in section. (4) Claims (1) to (3) characterized in that the cable introduction port is inclined in a direction that intersects at a predetermined angle with respect to a straight line connecting the introduction ports at opposing positions.
A junction box for the optical fiber cable described in any of paragraphs.