JP3400386B2 - Optical fiber communication cable protection structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for protecting an optical fiber communication cable of a type that is buried in the soil and preventing bending, disconnection and adhesion of water. More specifically, the present invention relates to a structure for connecting a case for accommodating a connection portion of an optical fiber communication cable, which is formed by connecting and extending a number of cables, and a sheath tube for accommodating a portion other than the connection portion of the cable.

[0002]

2. Description of the Related Art When an optical fiber communication cable is buried in the soil, it is necessary to protect the cable itself and the connection point of the cable. FIG. 6 shows a conventional protection structure.
As shown in FIG. 5, a case 93 for accommodating the connection portion 92 of the cable 91 is buried in the soil at a distance, and the holes 94 formed in the case are connected by a bellows 95, which is further arranged inside the bellows. A structure is known in which substantially the entire length of the cable is housed in the sheath tube 96 that is formed. The role of the bellows is to prevent water from entering the case and the sheath pipe through the gap between the hole and the sheath pipe even when the cable expands and contracts due to temperature change. The role of the sheath tube is to protect the cable from being bent or broken even when an external force is applied.

In the conventional structure, the bellows, which requires the same length as the space between the cases, has been a factor of increasing the material cost. In addition, the conventional structure is
It was very troublesome because the cable, which was several hundred meters long, had to be passed through the sheath tube as well as inside the bellows.

[0004]

SUMMARY OF THE INVENTION An object of the present invention developed in consideration of the above circumstances is to provide a protective structure for an optical fiber communication cable which is cheaper than conventional ones and which can be easily constructed. .

[0005]

According to a first aspect of the present invention, there is provided a protective structure for an optical fiber communication cable, wherein a case for accommodating a connection point of the optical fiber communication cable is buried in the soil at a distance. A sheath pipe that accommodates almost the entire length of the cable is arranged between the cases, and each end of the sheath pipe is provided by projecting into the case through a hole in the case, and between the tip of the sheath pipe and the hole in the case. , A connector that is expandable and contractible in the longitudinal direction of the cable is provided so as to surround the outside of the sheath pipe, and one end of the connector clamps the peripheral wall of the hole and the other end of the connector clamps the end of the sheath pipe. Thus, the invasion of water into the case and the sheath tube is prevented.

The "substantially full length of the cable" is a portion excluding both the connection portion of the cable and the portion in the vicinity of the connection portion.

According to the first aspect of the present invention, since the connector is housed in the space in the case, the connector can sufficiently exhibit the expansion and contraction performance. Even if the sheath tube expands and contracts with the cable due to temperature change and the distance between the tip of the sheath tube and the vent hole changes, the connector expands and contracts at the same time for the above reason, so that water can be completely prevented from entering the case and the sheath tube. Can be stopped.

The following demonstrates that the connector is significantly shorter than the bellows used in the conventional structure. The bellows used in the conventional structure has a length equal to the distance between the cases.
The total length of the cases is much shorter than the spacing between the cases. Since the connector is housed in the case, it is naturally shorter than the total length of the case. Therefore, it can be said that the connector is significantly shorter than the bellows used in the conventional structure.

The optical fiber communication cable protection structure described in claim 1 does not describe a specific structure of the connector, but as in the invention described in claim 2, the connector is provided with a male screw. It is composed of a cylinder, an outer cylinder with female thread, an expandable bellows, an annular packing, and a pair of fasteners, and a collar provided on the inner cylinder inserted into the hole and an outer cylinder screwed into the inner cylinder. The peripheral wall of the hole is sandwiched between the end face and the packing, and one end of the bellows is fixed to the outside of the outer or inner cylinder by one fastening tool, and the other end of the bellows is sheathed. The structure may be characterized in that it is fixed to the outside of the tip of the pipe by the other fastener.

The phrase "fixing one end of the bellows to the outside of the outer cylinder or the inner cylinder with one tightening tool" means that a portion for fixing one end of the bellows with the tightening tool is provided in the outer cylinder. This is a concept including a structure provided in the inner cylinder.

To mount the connector, the inner cylinder, the packing, the outer cylinder and the bellows are passed through the outer side of the sheath tube, the inner cylinder is inserted into the hole, and the outer cylinder is screwed into the inner cylinder. The sheath tube and the bellows are fixed to the inner cylinder or the outer cylinder by a fastener.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described with reference to the drawings. As shown in FIG. 5, the first embodiment of the protective structure for an optical fiber communication cable according to the present invention is the connection point 2 of the cable 1.
Is housed in a case 3 that can be opened and closed, and each end of the sheath pipe 4 that stores substantially the entire length of the cable 1 is inserted into the inside of the through hole 5 of the case 3 and the tip of the sheath pipe 4 is inserted in the case 3. Join the peripheral wall 6 of the punched hole 5 using a flexible connector 7,
This is a structure that secures both the seal at the joint between the connector 7 and the peripheral wall 6 and the seal at the joint between the connector 7 and the sheath tube 4.

The seal at the joint between the connector 7 and the peripheral wall 6 has a structure in which one end of the connector 7 is attached to the peripheral wall 6 in a sandwiched state. Further, the seal of the joint portion between the connector 7 and the sheath pipe 4 has a structure in which the other end portion of the connector 7 is attached in a state of being sandwiched between the distal end portion of the sheath pipe 4.

As shown in FIGS. 1 and 2, the connector 7 includes six parts, an inner cylinder 8 with a male screw, an outer cylinder 9 with a female screw, an expandable bellows 10, an annular packing 11, and small and large tightenings. It is composed of tools 12 and 13. Next, the details of each component will be described.

The inner cylinder 8 is formed so that the inner diameter is larger than the outer diameter of the sheath tube 4 and the outer diameter is slightly smaller than the punched hole 5, and a flange 14 is projectingly provided along the outer circumference of one end and the outer circumference of the other end. 1 male screw on the surface
5 is formed. The outer cylinder 9 has a female screw 16 to be screwed into the male screw 15 formed on the inner peripheral surface of one end portion, and an overhanging piece 17 corresponding to the collar 14 projecting along the outer periphery of the one end portion to form an outer peripheral surface. A locking groove 18 is provided in a part along the circumferential direction. Bellows 10 is made of elastic material, and bellows 1
Extending the cylindrical mounting portions 20 and 21 at both ends of 9,
One (left side in the figure) mounting portion 20 is formed to be slightly smaller than the outer diameter of the outer cylinder 9, and the locking groove 1 is formed on a part of the inner peripheral surface.
8 is provided along the circumferential direction, and the other (right side) mounting portion 21 is formed slightly smaller than the outer diameter of the sheath tube 4. The fasteners 12 and 13 connect the two parts by narrowing the diameter of the wire 23. More specifically, the fasteners 12 and 13 are C-shaped wires 2 arranged with a space left and right.
The flat plates 24 are fixed to both ends of the plate 3 so as to be opposed to each other with an interval vertically (in a direction perpendicular to the drawing).
Open a through hole in the center of the plate and use bolts B and nuts
This is a structure in which the distance between 4, 24 is narrowed. Through holes and nuts are not shown in the drawing.

The work of mounting the connector 7 is performed, for example, in the following procedure. First, the inner tube 8 and the packing 11 are inserted in order from the end of the sheath tube 4 accommodating substantially the entire length of the cable 1, then the sheath tube 4 is passed through the through hole 5, and then the outer tube 9 is attached to the sheath tube 4. The bellows 10 are inserted in order. Then, the inner cylinder 8
The outer cylinder 9 is screwed in, then the mounting portion 20 of the bellows 10 is inserted outside the outer cylinder 9, and the projection 22 is fitted in the locking groove 18 for positioning. To facilitate positioning,
The outer diameter of one end of the outer cylinder 9 is reduced in a stepped manner, and the mounting portion 20
The end surface of the abutment portion contacts the stepped portion. Finally,
The fastening tool 12 is fastened and fixed to the overlapping portion of the outer cylinder 9 and the mounting portion 20, and the fastening tool 13 is fastened to the mounting portion 21 and fixed to the sheath tube 4. The fasteners 12 and 13
The protrusions P are provided along the outer peripheral surfaces of the mounting portions 20 and 21 so that they will not laterally shift and come off.

In the second embodiment of the present invention, as shown in FIG. 3, a male screw 15 is provided on the outer peripheral surface of the intermediate portion of the inner cylinder 8, a female screw 16 is provided on the entire inner surface of the outer cylinder 9, and a collar 14 is provided. The outer diameter of the end portion on the opposite side is smaller than that of the male screw portion, and the mounting portion 20 of the bellows 10 is fixed to the small diameter portion.

In the third embodiment of the present invention, as shown in FIG. 4, a collar 14 is provided in the middle portion of the outer peripheral surface of the inner cylinder 8, and one end is disposed inside the case 3 with the collar 14 as a boundary. The other end projects from the hole 5 toward the outside of the case 3, the mounting portion 20 is fixed to the outer peripheral surface of the one end, and the male screw 15 provided on the other end.
The outer cylinder 9 is screwed in.

The present invention is not limited to the above embodiment. For example, in the first embodiment, the male screw 15 of the inner cylinder 8 may be formed long, and the female screw 16 may be formed on the entire inner peripheral surface of the outer cylinder 9. With this configuration, even if the thickness of the case 3 is slightly different, the peripheral wall 6 can be held between the inner cylinder 8 and the outer cylinder 9.
It is not necessary to prepare the inner cylinder 8 and the outer cylinder 9 having different sizes depending on the wall thickness.

[0020]

According to the invention of claim 1, the expandable connector housed in the case is a bellows having a conventional structure.
Since it has a much shorter structure than the other parts, the cost can be kept low. Further, the work of inserting the connector into the sheath tube is short and can be performed quickly, and as a result, the entire construction work for burying the cable in the soil is easier than in the past.

According to the second aspect of the present invention, since the connector is composed of the above-mentioned parts, when the connector is mounted, it suffices to insert, screw and tighten the parts. Can be done very easily.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an enlarged main part of a first embodiment of a protection structure for an optical fiber communication cable according to the present invention.

FIG. 2 is an exploded view of the connector shown in FIG.

FIG. 3 is a cross-sectional view of an essential part showing a second embodiment of the present invention.

FIG. 4 is a sectional view of an essential part showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the whole of the present invention.

FIG. 6 is an explanatory view showing an entire protection structure for a conventional optical fiber communication cable.

[Explanation of symbols]

1 Optical fiber communication cable (cable) 2 connection points 3 cases 4 sheath tube 5 holes 6 peripheral wall 7 connector 8 inner cylinder 9 outer cylinder 10 Bellows 11 packing 12,13 Fastener 14 Tsuba

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsukatsu Nakayama 9-3 Futshima, Fukushima-shi, Futukushima 9-2 (72) Inventor Ikumi Kobayashi 4-29-7 Minamimachi, Taichiro-ku, Sendai, Miyagi (72) Invention Person Hiroshi Naganuma Sakuragaoka 6-1, 18 Aoba-ku, Sendai City, Miyagi Prefecture Flat 103 Sakuragaoka B103 (56) References JP-A-3-260607 (JP, A) Actual Kaihei 9-227 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G02B 6/00 H02G 15/10

Claims (2)

(57) [Claims] A case (3) for accommodating a connection point (2) of an optical fiber communication cable (1) is buried in the soil at an interval, and a sheath tube (accommodating substantially the entire length of the cable (1) ( 4) is arranged between the cases (3, 3), and each end of the sheath pipe (4) is provided by projecting into the case (3) through a hole (5) provided in the case (3). ), A connector (7) which is expandable and contractible in the longitudinal direction of the cable is interposed between the distal end of the sheath tube (4) and the vent hole (5) so as to surround the outside of the sheath tube (4). ), The peripheral wall (6) of the hole (5) is clamped at one end, and the end of the sheath tube (4) is clamped at the other end of the connector (7). A protective structure for an optical fiber communication cable, characterized in that water is prevented from entering the pipe (4). 2. The connector (7) comprises an inner cylinder (8) with a male screw, an outer cylinder (9) with a female screw, an expandable bellows (10), a packing (11), and a pair of fasteners. (12,
13), and a collar (14) provided on the inner cylinder (8) inserted into the hole (5)
And the end surface of the outer cylinder (9) screwed into the inner cylinder (8), the peripheral wall (6) of the hole (5) is sandwiched with the packing (11) interposed, and the outer cylinder ( 9) Or the one end of the bellows (10) is attached to the outside of the inner cylinder (8) with one fastening tool (12).
The optical fiber communication cable according to claim 1, characterized in that the other end of the bellows (10) is fixed to the outside of the distal end of the sheath tube (4) by the other fastening tool (13). Protection structure.