JP3749532B2 - Fiber optic cable branch dam - Google Patents

Description

  The present invention belongs to the technical field of optical fiber cables, and particularly relates to a branch dam of an optical fiber cable.

  Optical fiber for optical communication is, for example, a multi-core optical fiber cable from a telephone station or a broadcasting station is wired by a utility pole or underground tunnel, and the multi-core optical fiber cable is branched in a closure installed in the middle of the cable. It is connected to another optical fiber cable, and is connected to each subscriber through a transmission node arranged ahead.

In general, a multi-core optical fiber cable having several tens to several hundreds of cores is used as the trunk cable, and a cable having about 2 to 8 cores is used between the closure and the transmission node.
When fixing the end of the optical fiber cable to the node, for example, as shown in FIG. 5 of Japanese Patent Laid-Open No. 10-54912 (Patent Document 1), the tension member is fixed to a fixing bracket in the node.

However, if a fixing metal fitting is provided inside the housing, the miniaturization of the node is hindered. Therefore, in the technique disclosed in Patent Document 1, a fixing adapter is attached to the outside of the housing and is arranged in the fixing adapter. By fixing the tension member to the fixing bracket, the space inside the housing is effectively used.
Japanese Patent Laid-Open No. 10-54912 (paragraphs 0021 to 0041, FIGS. 1 and 2)

  The technique disclosed in Patent Document 1 makes effective use of the space inside the casing by setting the fixing position of the tension member outside the casing. However, the structure of the fixing adapter is complicated and the cost is high. There's a problem.

The branch dam of the optical fiber cable according to claim 1 is connected to the end of the optical fiber cable by inserting a slot of the optical fiber cable into one end, and each of the optical fiber cables from the other drawing end. A branch dam main trunk from which a single-core cord connected to a fiber line is drawn, a holding plate arranged with one side in contact with a lead end of the branch dam trunk, and a central portion of the branch dam trunk penetrate A fixing bracket that is fixed to the end of the tension member of the optical fiber cable protruding from the holding plate and prevents the end of the tension member from being pulled into the branch dam main part, and a branch dam main part the screwed into the branch dam main trunk in the radial direction, by inserting a part that fits into the branch dam main trunk of the slot, those tips to said tension member And a fixing screw to be.

  In this branch dam, the fixing bracket fixed to the end portion of the tension member prevents the end portion of the tension member from being drawn into the branch dam main portion side. Further, since the tip of the fixing screw screwed into the branch dam main portion is in contact with the tension member, the tension member and the branch dam main portion are also connected by the fixing screw. As a result, the relative movement between the tension member and the branch dam trunk in the direction of drawing the end of the tension member into the branch dam trunk is restricted.

  That is, if the branch dam is fixed to a casing such as a node, the tension member is fixed via the branch dam. As a result, the tension member acting on the optical fiber cable can be assumed (strength resistance of the optical fiber cable is ensured), and the optical fiber in the optical fiber cable can be prevented from being broken by the tension.

In addition, the slot of the optical fiber cable is fitted into the end portion of the branch dam main portion, and the fixing screw is inserted through the portion of the slot fitted into the branch dam main portion and the tip is brought into contact with the tension member. Therefore, the tensile strength is further increased.
Further, the branch dam of the optical fiber cable according to claim 2 is the branch dam of the optical fiber cable according to claim 1, wherein the branch dam main portion includes a single core connected to each fiber line of the optical fiber cable. Since the passage of the cord is provided, and the holding plate is provided with a hole or a notch for passing the single core cord, the single core cord passed through the passage of the branch dam main portion is provided. Can be pulled out of the holding plate.

As described above, if the branch dam of the optical fiber cable according to the first aspect is used, it is not necessary to fix the tension member inside the casing with a metal fitting or the like, and the miniaturization of the node or the like is not hindered. In addition, since the tension member has a simple configuration in which the tension member is fixed to the trunk portion of the branch dam by a combination of a fixing screw, a fixing bracket, and a holding plate, the structure is simple and the cost can be reduced.
Also, since the fixing screw is inserted through the portion of the slot where the main branch of the branch dam is inserted and the tip is brought into contact with the tension member, the tension resistance is improved, so that the optical fiber is pulled by the tension acting on the optical fiber cable. Breakage can be prevented more reliably.

The branch dam of the optical fiber cable according to claim 2 can pull out the single-core cord passed through the branch dam main portion from the holding plate.

  Next, an embodiment of the present invention will be described with reference to the best mode.

  As shown in FIG. 1, an optical fiber cable 10 includes a tension member 12 that is a steel wire, a polyethylene slot 14 having the tension member 12 as a core, and a tape core wire that is inserted into a fiber accommodation groove 16 of the slot 14. 18, a presser winding 20 of a water-absorbing polymer tape wound around the slot 14 and a polyethylene sheath 22 as an outer shell. The tape core wire 18 is formed by arranging a plurality of optical fibers in parallel to form a tape. The optical fiber cable 10 itself is a known one.

The branch dam 30 of the optical fiber cable 10 has a structure as shown in FIG.
First, at the end of the optical fiber cable 10, the sheath 22 and the presser winding 20 (not shown in FIG. 2) are removed, and the slot 14 is exposed. In addition, the slot 14 is also cut off beyond that, and only the tension member 12 is extended.

  An end including the exposed slot 14 is fitted into a fitting hole 34 provided at an end of a branch dam main trunk 32 made of polyethylene and having a round bar shape, and is adhered to the fitting hole 34. A fixing screw 36 is screwed onto the branch dam main portion 32 along the radial direction, and the fixing screw 36 penetrates through the slot 14 and abuts the tip of the fixing member 36 against the tension member 12.

A holding plate 38, which is a disc-shaped sheet metal, is disposed on the other end (drawing end) 33 of the branch dam main trunk portion 32 so that one surface thereof is in contact with the drawing end 33.
The tension member 12 passes through the central portion of the branch dam main trunk portion 32, and further passes through the central hole 38 a of the holding plate 38 and protrudes from the holding plate 38.

  The protruding end 12a of the tension member 12 is covered with a cap-shaped fixing bracket 40, and the fixing bracket 40 is fixed to the protruding end 12a by caulking. Since the inner diameter of the center hole 38a is substantially equal to the diameter of the tension member 12 and the outer diameter of the fixing bracket 40 is larger than those diameters, the protruding end 12a to which the fixing bracket 40 is fixed is pulled into the branch dam main portion 32 side. It is not possible.

  Although not shown, the branch dam main trunk portion 32 is provided with a path of a single core cord 42 connected to each fiber wire of the tape core wire 18 of the optical fiber cable 10, and the holding plate 38 has a passage. Also, a hole or notch for passing the single core cord 42 is provided, and each single core cord 42 is drawn out from the leading end 33 of the branch dam main portion 32.

Then, the branch dam main portion 32 is covered with the heat shrinkable tube 44 from the optical fiber cable 10.
As shown in FIG. 3, the end of the optical fiber cable 10 to which the branch dam 30 is attached as shown in FIG. 2 is fixed to a housing such as a node by an attachment fitting that holds the branch dam 30. Each single-core cord 42 is connected to a coupler unit in the node by a connector (not shown) provided at the end thereof.

When a tension acts on the optical fiber cable 10 in the state shown in FIG. 3, this tension acts as a force for pulling the optical fiber cable 10 from the branch dam 30 held by the mounting bracket.
However, in the branch dam 30, the fixing bracket 40 fixed to the protruding end 12a of the tension member 12 prevents the protruding end 12a of the tension member 12 from being pulled into the branch dam main portion 32 side.

  Further, since the fixing screw 36 screwed into the branch dam main portion 32 passes through the slot 14 in the branch dam main portion 32 and the tip thereof is in contact with the tension member 12, the slot 14 and the tension member are also fixed by the fixing screw 36. 12 and the branch dam main part 32 are connected.

As a result, the relative movement between the tension member 12 and the branch dam trunk 32 in the direction in which the protruding end 12a of the tension member 12 is pulled into the branch dam trunk 32 is restricted.
That is, if the branch dam 30 is fixed to a casing such as a node, the tension member 12 is fixed via the branch dam 30. Thereby, the tension member 12 can take over the tension acting on the optical fiber cable 10 (the tension resistance of the optical fiber cable 10 is ensured), and the tape core wire 18 (optical fiber) accommodated in the optical fiber cable 10 by the tension. Fiber) can be prevented from breaking.

  The best embodiment of the present invention has been described above according to the embodiment. However, the present invention is not limited to such an embodiment, and it goes without saying that the present invention can be implemented in various ways without departing from the gist of the present invention. .

It is structure explanatory drawing of the optical fiber cable of an Example, (a) is a perspective view, (b) is a cross-sectional view. Explanatory drawing of the connection structure of the branch dam and optical fiber cable of an Example. The illustration figure in the case of connecting an optical fiber cable to a housing | casing in the branch dam of an Example.

Explanation of symbols

10: optical fiber cable,
12 ... tension member,
12a ... projecting end,
14 ... slot,
16: Fiber receiving groove,
18 ... Tape core (optical fiber),
30 ... Branch dam,
32 ... Branch dam manager,
33 ... drawer end,
36... Fixing screw,
38 ... holding plate,
40: Fixing bracket,
42: Single core cord.

Claims (2)

A branch in which a slot of an optical fiber cable is inserted into one end and connected to the end of the optical fiber cable, and a single core cord connected to each fiber line of the optical fiber cable is drawn out from the other drawing end The dam boss,
A holding plate arranged with one side in contact with the leading end of the branch dam main trunk;
It is fixed to the end of the tension member of the optical fiber cable that penetrates the center of the branch dam trunk and protrudes from the holding plate, and the end of the tension member is drawn into the branch dam trunk side. Fixing brackets to block,
A screw that is screwed into the branch dam trunk along the radial direction of the branch dam trunk, is inserted through a portion of the slot that is fitted into the branch dam trunk, and a tip is brought into contact with the tension member. A branch dam for an optical fiber cable, characterized by comprising a screw. In the branch dam of the optical fiber cable according to claim 1,
The branch dam trunk is provided with a single-core cord passage connected to each fiber line of the optical fiber cable,
A branch dam for an optical fiber cable, wherein the holding plate is provided with a hole or a notch for allowing the single core cord to pass therethrough.

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