Cylindrical member, terminal structure of optical fiber composite overhead ground wire, and storage structure for connection portion of optical fiber composite overhead ground wire

Abstract

To provide a cylindrical member capable of constructing a terminal structure of an optical fiber compound overhead earth wire that does not easily damage optical cables, and a storage structure of a connection part of an optical fiber compound overhead earth wire.SOLUTION: A cylindrical member 4 made of rubber, comprises a first cylindrical part 41, a second cylindrical part 42 continuous in an axial direction of the first cylindrical part, and a slit extending over the entire axial length of the cylindrical member, where an inner diameter of the first cylindrical part corresponds to an outer diameter of a metal pipe 32 arranged inside an optical fiber compound overhead dearth wire, an inner diameter of the second cylindrical part is larger than or equal to an outer diameter of an optical cable 31 arranged inside the metal pipe and less than an inner diameter of the metal pipe, and of the slits, a second slit part provided in the second cylindrical part is substantially closed in a circumferential direction of the second cylindrical part.SELECTED DRAWING: Figure 4A

Description

[Technical field]

[0001] The present invention relates to a tubular member, a terminal structure for an optical fiber composite overhead ground wire, and a storage structure for a connection portion of an optical fiber composite overhead ground wire. [Background technology]

[0002] The optical fiber composite overhead ground wire (OPGW) of Patent Document 1 has an optical unit section and a wire layer (metal wire). The optical unit section has an optical fiber core (optical cable) and a metal tube that houses the optical fiber core. The wire layer is provided by twisting a plurality of wires together so as to cover the outer periphery of the optical unit section (metal tube). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-201267 A Summary of the Invention [Problem to be solved by the invention]

[0004] The optical cable of an OPGW is connected to the optical cable of another OPGW inside a connection box. During this connection, the metal tube is sequentially exposed from the metal wire of the OPGW, and the optical cable is exposed from the metal tube. The optical cable is exposed from the metal tube by cutting the metal tube. When a metal tube is cut, a burr that protrudes radially inward from the inner periphery of the end face of the metal tube is likely to be formed. Therefore, the optical cable exposed from the metal tube may come into contact with the inner periphery (burr) of the end face of the metal tube and be damaged.

[0005] Therefore, one object of the present invention is to provide a tubular member that can be used to construct a terminal structure for an optical fiber composite overhead ground wire that is less susceptible to damage to optical cables, and a storage structure for the connection portion of the optical fiber composite overhead ground wire.

[0006] Another object of the present invention is to provide a terminal structure for an optical fiber composite overhead ground wire and a storage structure for a connection portion of the optical fiber composite overhead ground wire that are less susceptible to damage to the optical cable. [Means for solving the problem]

[0007] The cylindrical member according to the present invention comprises: A cylindrical member made of rubber, A first cylindrical portion; A second cylindrical portion continuous with the first cylindrical portion in an axial direction; a slit extending over the entire axial length of the cylindrical member; an inner diameter of the first cylindrical portion corresponds to an outer diameter of a metal tube disposed inside the optical fiber composite overhead ground wire; an inner diameter of the second cylindrical portion is equal to or larger than an outer diameter of the optical cable disposed inside the metal tube and smaller than an inner diameter of the metal tube; Of the slits, a second slit portion provided in the second cylindrical portion is substantially closed in the circumferential direction of the second cylindrical portion.

[0008] The terminal structure of the optical fiber composite overhead ground wire according to the present invention comprises: an optical fiber composite overhead ground wire including an optical cable, a metal tube for housing the optical cable, and a metal wire provided on an outer periphery of the metal tube; a cylindrical member that covers an outer periphery of the end of the metal tube and an outer periphery of the optical cable drawn out from the end of the metal tube in a continuous manner, The cylindrical member is the cylindrical member of the present invention, the first cylindrical portion of the cylindrical member covers an outer periphery of an end portion of the metal pipe, The second tubular portion of the tubular member covers an outer periphery of the optical cable pulled out from the end of the metal tube.

[0009] The storage structure for the joint portion of the optical fiber composite overhead ground wire according to the present invention comprises: A terminal structure of a first optical fiber composite overhead ground wire; a termination structure of a second optical fiber composite overhead ground wire; a connection portion that connects the optical cables drawn out from each of the terminal structures; a connection box that houses the connection portion, Each of the above-mentioned terminal structures is a terminal structure of the optical fiber composite overhead ground wire of the present invention. Effect of the Invention

[0010] The tubular member according to the present invention can be used to construct a terminal structure for a composite optical fiber ground wire and a storage structure for the connection portion of the composite optical fiber ground wire, in which the optical cable is less likely to be damaged.

[0011] The terminal structure of the optical fiber composite overhead ground wire according to the present invention and the storage structure for the connection portion of the optical fiber composite overhead ground wire according to the present invention make it difficult for the optical cable to be damaged. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a plan view showing an outline of a storage structure for a joint portion of an optical fiber composite overhead ground wire according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of the optical fiber composite overhead ground wire provided in the storage structure for the joint portion of the optical fiber composite overhead ground wire according to the first embodiment. [Diagram 3] FIG. 3 is a plan view showing an outline of a terminal structure of the optical fiber composite overhead ground wire provided in a storage structure for a joint portion of the optical fiber composite overhead ground wire according to the first embodiment. [Figure 4A] FIG. 4A is a vertical cross-sectional view showing a part of the terminal structure of the optical fiber composite overhead ground wire cut along the (A)-(A) cutting line in FIG. [Figure 4B] FIG. 4B is a cross-sectional view showing a part of the terminal structure of the optical fiber composite overhead ground wire cut along the (B)-(B) cutting line in FIG. 4A. [Diagram 5] FIG. 5 is a plan view showing an outline of another example of a terminal structure of a composite optical fiber overhead ground wire provided in a storage structure for a joint portion of the composite optical fiber overhead ground wire according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <<Description of the embodiment of the present invention>> First, the embodiments of the present invention will be listed and described.

[0014] (1) A cylindrical member according to one aspect of the present invention comprises: A cylindrical member made of rubber, A first cylindrical portion; A second cylindrical portion continuous with the first cylindrical portion in an axial direction; a slit extending over the entire axial length of the cylindrical member; an inner diameter of the first cylindrical portion corresponds to an outer diameter of a metal tube disposed inside the optical fiber composite overhead ground wire; an inner diameter of the second cylindrical portion is equal to or larger than an outer diameter of the optical cable disposed inside the metal tube and smaller than an inner diameter of the metal tube; Of the slits, a second slit portion provided in the second cylindrical portion is substantially closed in the circumferential direction of the second cylindrical portion.

[0015] The above-mentioned tubular member can be attached to the metal tube and the optical cable of the optical fiber composite overhead ground wire from the outer periphery of the metal tube and the optical cable. The reason is that the tubular member is made of rubber and has a slit extending over its entire axial length, so that the slit can be widened when attached and closed after attachment. In addition, the above-mentioned tubular member has a first tubular portion having an inner diameter corresponding to the outer diameter of the metal tube, so that the first tubular portion can be tightly attached to the metal tube. Furthermore, the above-mentioned tubular member has a second tubular portion having an inner diameter equal to or larger than the outer diameter of the optical cable and smaller than the inner diameter of the metal tube, so that the optical cable can be easily centered with respect to the metal tube and the optical cable can be prevented from contacting the inner peripheral edge of the end of the metal tube. In particular, since the second slit portion is substantially closed in the circumferential direction, it is possible to prevent the optical cable from slipping out of the tubular member through the second slit portion. Therefore, it is possible to prevent the optical cable from contacting the inner peripheral edge of the end of the metal tube over the entire circumferential direction of the second tubular portion. Therefore, the above-mentioned tubular member can form a terminal structure for an optical fiber composite overhead ground wire and a storage structure for the connection portion of the optical fiber composite overhead ground wire in which the optical cable is less likely to be damaged.

[0016] It is also possible to attach a resin tubular member with a C-shaped cross section to the optical cable from the outer periphery of the optical cable and slide it in the axial direction of the optical cable to be interposed between the optical cable and the metal tube. Since this tubular member is attached to the optical cable from the outside, it is necessary to make the opening of the C-shape larger than the outer diameter of the optical cable. This is because the opening cannot be widened when the tubular member is attached because it is made of resin. Therefore, with a resin tubular member, there is a risk that the optical cable will slip out of the opening to the outside of the tubular member and come into contact with the inner periphery of the end face of the metal tube.

[0017] (2) As one embodiment of the cylindrical member, The length of the second cylindrical portion along the axial direction is, for example, 3 mm or more and 50 mm or less.

[0018] The second tubular portion having an axial length of 3 mm or more has a sufficient length, making it easy to center the optical cable in the metal tube, and the second tubular portion having an axial length of 50 mm or less is not excessively long, preventing the tubular member from becoming excessively long.

[0019] (3) As one embodiment of the cylindrical member, the cylindrical member has a third cylindrical portion continuous with the second cylindrical portion on an axially opposite side to the first cylindrical portion, The inner diameter of the third cylindrical portion increases in a direction away from the second cylindrical portion, The slit may further extend over the entire axial length of the third cylindrical portion.

[0020] In the above-mentioned tubular member, the inner diameter of the third tubular portion increases in the direction away from the second tubular portion, so that it is easy to insert a plurality of tubes, which will be described later, into the third tubular portion. Also, in the above-mentioned tubular member, the slits extend over the entire axial length of the third tubular portion, so that the tubular member having the third tubular portion can be attached to the metal tube and the optical cable from the outer circumferential side of the metal tube and the optical cable.

[0021] (4) As one embodiment of the cylindrical member of (3), The inclination angle of the inner circumferential surface of the third cylindrical portion with respect to the axis of the third cylindrical portion is preferably 1° or more and 45° or less.

[0022] A third tubular portion having an inner peripheral surface with an inclination angle of 1° or more has a large inner diameter on the side opposite the first tubular portion in the axial direction of the third tubular portion. Therefore, the above-mentioned tubular member makes it easy to insert multiple tubes, which will be described later, into the third tubular portion. A third tubular portion having an inner peripheral surface with an inclination angle of 45° or less does not have an excessively large angle. Therefore, the above-mentioned tubular member does not have an excessively thin thickness on the opposite side of the third tubular portion. Therefore, the strength of the opposite side of the third tubular portion does not become too low. The above-mentioned thickness refers to the difference between the inner diameter and the outer diameter of the third tubular portion.

[0023] (5) As one embodiment of the cylindrical member, The material of the cylindrical member may include at least one selected from the group consisting of urethane rubber, silicone rubber, chloroprene rubber, and ethylene propylene rubber.

[0024] The above-mentioned cylindrical member has an excellent balance between elasticity and rigidity, and therefore is easy to attach to the metal pipe and the optical cable, and is difficult to come off from the metal pipe and the optical cable.

[0025] (6) A terminal structure of an optical fiber composite overhead ground wire according to one aspect of the present invention comprises: an optical fiber composite overhead ground wire including an optical cable, a metal tube for housing the optical cable, and a metal wire provided on an outer periphery of the metal tube; a cylindrical member that covers an outer periphery of the end of the metal tube and an outer periphery of the optical cable drawn out from the end of the metal tube in a continuous manner, The cylindrical member is the cylindrical member according to any one of (1) to (5) above, the first cylindrical portion of the cylindrical member covers an outer periphery of an end portion of the metal pipe, The second tubular portion of the tubular member covers an outer periphery of the optical cable pulled out from the end of the metal tube.

[0026] The terminal structure of the above-mentioned optical fiber composite overhead ground wire makes it easy to center the optical cable relative to the metal tube, and is equipped with a tubular member that can prevent the optical cable from coming into contact with the inner edge of the end face of the metal tube, making the optical cable less likely to be damaged.

[0027] (7) As one embodiment of the terminal structure of the above-mentioned optical fiber composite overhead ground wire, The metal tube has an inner tube and an outer tube provided on the inside and outside, the inner tube is constructed from stainless steel; The outer tube may include aluminum.

[0028] In the above-mentioned terminal structure of the optical fiber composite overhead ground wire, the inner tube is made of stainless steel, which has excellent strength, so that the strength of the metal tube can be increased. Also, in the above-mentioned terminal structure of the optical fiber composite overhead ground wire, the outer tube is made of an aluminum-based material, so that the metal tube and the metal wire can be made of the same metal. Therefore, the above-mentioned terminal structure of the optical fiber composite overhead ground wire can suppress corrosion caused by contact between different metals.

[0029] (8) As one embodiment of the terminal structure of the above-mentioned optical fiber composite overhead ground wire, The optical fiber cable may have a gel filled between the metal tube and the optical fiber cable.

[0030] The above-mentioned terminal structure of the optical fiber composite overhead ground wire can improve the watertightness inside the metal pipe by using the jellies. Also, the above-mentioned terminal structure of the optical fiber composite overhead ground wire can reduce the friction of the optical cable against the inner peripheral surface of the metal pipe by using the jellies.

[0031] (9) As one embodiment of the terminal structure of the above-mentioned optical fiber composite overhead ground wire, The optical cable includes: A plurality of optical fiber cores; and a plurality of tubes each containing a predetermined number of the plurality of optical fiber cores.

[0032] The above-mentioned terminal structure of the optical fiber composite overhead ground wire makes it easy to handle a plurality of optical fiber cores.

[0033] (10) As one embodiment of the terminal structure of the optical fiber composite overhead ground wire of (9) above, a first shrink tube continuously covering an outer circumferential surface of the cylindrical member and an outer circumferential surface of the metal tube; The second shrink tube covers the outer circumferential surface of the cylindrical member and the outer circumferential surfaces of the plurality of tubes in a continuous manner.

[0034] The above-mentioned terminal structure of the optical fiber composite overhead ground wire can suppress misalignment of the tubular member with respect to the metal tube by the first shrinkable tube. Also, the above-mentioned terminal structure of the optical fiber composite overhead ground wire can suppress misalignment of the multiple tubes with respect to the tubular member by the second shrinkable tube.

[0035] (11) A storage structure for a connection portion of an optical fiber composite overhead ground wire according to one aspect of the present invention includes: A terminal structure of a first optical fiber composite overhead ground wire; a termination structure of a second optical fiber composite overhead ground wire; a connection portion that connects the optical cables drawn out from each of the terminal structures; a connection box that houses the connection portion, Each of the terminal structures is a terminal structure of the optical fiber composite overhead ground wire according to any one of (6) to (10) above.

[0036] The storage structure for the connection portion of the above-mentioned optical fiber composite overhead ground wire has a terminal structure that makes it easy to center the optical cable relative to the metal tube, and is equipped with a tubular member that can suppress contact of the optical cable with the inner edge of the end face of the metal tube, making it less likely for the optical cable to be damaged.

[0037] Detailed Description of the Preferred Embodiments of the Invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings, in which the same reference numerals indicate the same objects.

[0038] First Embodiment [Housing structure for optical fiber composite overhead ground wire (OPGW) connection] A storage structure 1 for a connection part of an OPGW according to the first embodiment will be described with reference to Figs. 1 to 3, 4A, and 4B. The storage structure 1 for a connection part of an OPGW according to this embodiment includes a terminal structure 21 of a first OPGW, a terminal structure 22 of a second OPGW, a connection part 6, and a connection box 7 (Fig. 1). The terminal structure 21 of the first OPGW and the terminal structure 22 of the second OPGW each include an OPGW 3. Each OPGW 3 includes an optical cable 31, a metal tube 32 that stores the optical cable 31, and a metal wire 34 provided on the outer periphery of the metal tube 32 (Fig. 2). The connection part 6 is formed by connecting the optical cables 31 drawn out from the OPGW 3 of each terminal structure to each other (Fig. 1). The connection box 7 stores the connection part 6. One of the features of the storage structure 1 for the connection part of the OPGW according to this embodiment is that the terminal structures 21, 22 of each OPGW include a tubular member 4 (FIG. 4A) of a specific structure that continuously covers the outer periphery of the end of the metal tube 32 and the outer periphery of the optical cable 31 drawn out from the end of the metal tube 32. Each component will be described in detail below. For convenience of explanation, the first heat shrink tube 51 and the second heat shrink tube 52 are omitted in FIGS. 4A and 4B.

[0039] [OPGW terminal structure] The first OPGW terminal structure 21 and the second OPGW terminal structure 22 each have an OPGW 3 and a cylindrical member 4 (FIG. 4A). The OPGW terminal structures 21 and 22 each have a common structure.

[0040] (OPGW) The OPGW 3 has both a function of protecting the power transmission line from lightning and a communication function. The OPGW 3 includes an optical cable 31, a metal pipe 32, and a metal wire 34 (FIG. 2).

[0041] Optical fiber cable The optical cable 31 has a communication function. The optical cable 31 has at least one optical fiber unit. The optical fiber unit refers to a collection of multiple optical fiber cores 311. The optical fiber unit includes a case in which a string is wound around only the multiple optical fiber cores 311 without using a tension member, and a case in which the multiple optical fiber cores 311 are twisted around the outer periphery of a core tension member. The string is not shown in the figure. The string is wound at a pitch such that the optical fiber cores 311 are exposed. Alternatively, the optical cable 31 may have multiple optical fiber units having the above-mentioned core tension member twisted around the outer periphery of a unit tension member.

[0042] The optical cable 31 of this embodiment has a plurality of optical fiber units. The optical cable 31 does not have a tension member for the units. Each optical fiber unit is formed by wrapping a string around only a predetermined number of optical fiber cores 311 without using a tension member for the cores. Each string is color-coded. Therefore, each bundle of optical fiber cores 311 can be distinguished. This color coding makes it difficult to make a mistake when inserting each bundle of optical fiber cores 311 into a tube 312 (FIG. 4A) described later. The optical cable 31 of this embodiment does not have a sheath that covers the plurality of optical fiber units collectively.

[0043] An end of the optical cable 31 is exposed from an end of the metal tube 32 (FIG. 4A). The optical cable 31 exposed from the metal tube 32 is disposed in the junction box 7 (FIG. 1). The optical cable 31 disposed in the junction box 7 is covered with a second tubular portion 42, a third tubular portion 43, a tube 312, etc., which will be described later.

[0044] ·tube The optical cable 31 preferably includes a plurality of tubes 312 housing the optical fiber units (FIG. 4A). That is, each tube 312 houses a predetermined number of optical fiber cores 311. The optical fiber units are easy to handle by the tubes 312. The tubes 312 are color-coded like the string. The material of the tubes 312 can be, for example, silicone resin. One end of each tube 312 is disposed inside a third tube portion 43 of the tubular member 4 described later. That is, a portion of each tube 312 is housed inside the third tube portion 43. The other end of each tube 312 is disposed inside the connection box 7.

[0045] <Metal pipe> The metal tube 32 stores the optical cable 31 inside (FIGS. 2 and 4A). In this embodiment, the metal tube 32 has an inner tube 321 and an outer tube 322 provided inside and outside. The inner tube 321 and the outer tube 322 are joined to each other. The metal tube 32 in which the inner tube 321 and the outer tube 322 are joined may be a clad tube. The material of the inner tube 321 may be stainless steel. The inner tube 321 made of stainless steel has excellent strength. Therefore, the strength of the metal tube 32 is high. The material of the outer tube 322 may be aluminum (Al) or an Al alloy. The outer tube 322 made of an Al-based material may be the same metal as the metal wire 34. Therefore, corrosion caused by contact between different metals can be suppressed. The metal tube 32 may be, for example, a single tube made of Al or an Al alloy. The end of the metal tube 32 is exposed from the end of the metal wire 34. The exposed end of the metal tube 32 is disposed within the junction box 7 .

[0046] <Jerry> The metal tube 32 is preferably filled with gel 33 that fills the gap between the optical cable 31 and the metal tube 32. The gel 33 improves the watertightness of the inside of the metal tube 32. The gel 33 also reduces friction of the optical cable 31 against the inner peripheral surface of the metal tube 32. Examples of materials for the gel 33 include synthetic oils containing fatty acid carbides and silicon dioxide.

[0047] Metal Wire The metal wire 34 protects the power transmission line from lightning strikes. The metal wire 34 is formed by twisting a plurality of strands 341 around the outer periphery of the metal pipe 32 (FIG. 2). In this embodiment, each strand 341 is made of an aluminum-clad steel wire. The number of strands 341 can be selected as appropriate, and is six in this embodiment. The number of strands 341 may be, for example, seven. The shape of each strand 341 can be selected as appropriate, and is fan-shaped in this embodiment. The shape of each strand 341 may be, for example, circular.

[0048] (Cylindrical member) The cylindrical member 4 covers the outer periphery of the end of the metal tube 32 and the outer periphery of the optical cable 31 drawn out from the end of the metal tube 32 in a continuous manner (FIG. 4A). The cylindrical member 4 is disposed in the junction box 7. The material of the cylindrical member 4 may be rubber. The material of the cylindrical member 4 preferably includes at least one selected from the group consisting of urethane rubber, silicone rubber, chloroprene rubber, and ethylene propylene rubber. When the cylindrical member 4 includes a plurality of kinds of rubber, the cylindrical member 4 may be partially composed of different rubbers. These rubbers have an excellent balance between elasticity and rigidity, so that they are easily attached to the metal tube 32 and the optical cable 31 and are difficult to come off from the metal tube 32 and the optical cable 31. In this embodiment, the outer diameter of the cylindrical member 4 is uniform over the entire length in the axial direction. The cylindrical member 4 includes a first cylindrical portion 41, a second cylindrical portion 42, and a slit 44.

[0049] <First cylindrical part> The first tubular portion 41 covers the outer periphery of the metal tube 32. The inner peripheral surface of the first tubular portion 41 is cylindrical. The inner diameter of the first tubular portion 41 is uniform in the axial direction of the first tubular portion 41 (the left-right direction on the paper surface of FIG. 4A ). The inner diameter of the first tubular portion 41 corresponds to the outer diameter of the metal tube 32. In other words, the inner diameter of the first tubular portion 41 corresponds to the outer diameter of the outer tube 322. Therefore, the inner peripheral surface of the first tubular portion 41 is in close contact with the metal tube 32.

[0050] The length along the axial direction of the first tubular portion 41 is preferably, for example, 3 mm or more and 50 mm or less. The first tubular portion 41 having an axial length of 3 mm or more has a sufficient length and is therefore easily attached to the metal tube 32. The first tubular portion 41 having an axial length of 50 mm or less is not excessively long, and therefore the tubular member 4 itself does not become excessively long.

[0051] <Second cylinder part> The second tubular portion 42 covers the outer periphery of the optical fiber 311 in the optical cable 31. The second tubular portion 42 is provided continuously with the first tubular portion 41 in the axial direction.

[0052] The inner peripheral surface of the second tube portion 42 is cylindrical. The inner diameter of the second tube portion 42 is uniform in the axial direction of the second tube portion 42. The inner diameter of the second tube portion 42 is equal to or larger than the outer diameter of the optical cable 31 and smaller than the inner diameter of the metal tube 32. The outer diameter of the optical cable 31 refers to the outer diameter that envelops a plurality of optical fiber units. When the optical cable 31 has a unit tension member, the outer diameter of the optical cable 31 refers to the outer diameter that envelops a plurality of optical fiber units including the unit tension member. The second tube portion 42 makes it easy to center the optical cable 31 with respect to the metal tube 32, and can prevent the optical cable 31 from contacting the inner peripheral edge of the end of the metal tube 32. Therefore, damage to the optical cable 31 can be prevented. The end face of the second tube portion 42 on the first tube portion 41 side abuts and stops the end face of the metal tube 32.

[0053] The length along the axial direction of the second tubular portion 42 is preferably, for example, 3 mm or more and 50 mm or less. The second tubular portion 42 having an axial length of 3 mm or more has a sufficient length, so that it is easy to center the optical cable 31 relative to the metal tube 32. The second tubular portion 42 having an axial length of 50 mm or less is not excessively long, so that the tubular member 4 itself does not become excessively long.

[0054] <Third cylinder part> The cylindrical member 4 preferably further has a third cylindrical portion 43. The third cylindrical portion 43 is provided continuously on the opposite side of the second cylindrical portion 42 from the first cylindrical portion 41 in the axial direction. The third cylindrical portion 43 covers the outer periphery of the optical cable 31 exposed from the second cylindrical portion 42. Specifically, the third cylindrical portion 43 covers the outer periphery of the optical fiber core 311 and the outer periphery of the tube 312. That is, one end side of the tube 312 is inserted into the third cylindrical portion 43 as described above.

[0055] The inner peripheral surface of the third tubular portion 43 is cylindrical. The inner diameter of the third tubular portion 43 increases from the second tubular portion 42 side toward the opposite side. Therefore, the third tubular portion 43 can easily insert multiple tubes 312 therein. The minimum inner diameter of the third tubular portion 43 is the same as the inner diameter of the second tubular portion 42. The inclination angle α of the inner peripheral surface of the third tubular portion 43 with respect to the axis of the third tubular portion 43 is preferably, for example, 1° or more and 45° or less. The third tubular portion 43 having an inner peripheral surface with an inclination angle α of 1° or more has a large inner diameter on the opposite side of the third tubular portion 43. Therefore, the third tubular portion 43 can easily insert multiple tubes 312 therein. The third tubular portion 43 having an inner peripheral surface with an inclination angle α of 45° or less does not have an excessively large angle. Therefore, although it depends on the length of the third tubular portion 43 along the axial direction, the thickness of the opposite side of the third tubular portion 43 does not become too thin. Therefore, the strength of the opposite side of the third cylindrical portion 43 is not too low. The thickness refers to the difference between the inner diameter and the outer diameter of the third cylindrical portion 43.

[0056] The length along the axial direction of the third tubular portion 43 is preferably, for example, 3 mm or more and 50 mm or less. The third tubular portion 43 having an axial length of 3 mm or more has a sufficient length, so that it is easy to insert multiple tubes 312. The third tubular portion 43 having an axial length of 50 mm or less is not excessively long, so that the tubular member 4 itself does not become excessively long.

[0057] <slit> The slits 44 are provided to allow the tubular member 4 to be attached to the outer periphery of the metal tube 32 and the outer periphery of the optical cable 31 from the outer periphery side (FIG. 4B). Therefore, the tubular member 4 can be easily attached to the outer periphery of the metal tube 32 and the outer periphery of the optical cable 31. This is because it is not necessary to insert the tubular member 4 into the optical cable 31 from the tip. The length of the optical cable 31 inside the connection box 7 is, for example, several meters. Therefore, it is very complicated to insert the tubular member 4 into the optical cable 31 from the tip.

[0058] The slit 44 extends over the entire axial length of the tubular member 4. The slit 44 has a first slit portion, a second slit portion 442 (FIG. 4B), and a third slit portion. The first slit portion and the third slit portion are not shown. The first slit portion extends over the entire axial length of the first tubular portion 41. The second slit portion 442 extends over the entire axial length of the second tubular portion 42. The third slit portion extends over the entire axial length of the third tubular portion 43. The first slit portion, the second slit portion 442, and the third slit portion are linearly continuous with each other along the axial direction of the tubular member 4.

[0059] As shown in FIG. 4B, the second slit portion 442 is substantially closed in the circumferential direction of the second tube portion 42. FIG. 4B simplifies the optical fiber core 311 for convenience of explanation. Substantially closed means that the second slit portion 442 is closed without any gap, and may be provided with a gap that does not allow the optical fiber core 311 to slip out of the tube-shaped member 4 through the second slit portion 442. By substantially closing the second slit portion 442, it is possible to prevent the optical cable 31 from contacting the inner peripheral edge of the end portion of the metal tube 32 over the entire circumference of the second tube portion 42 in the circumferential direction. The first slit portion may be substantially closed in the circumferential direction of the first tube portion 41 like the second slit portion 442, or may not be closed. This is because the first slit portion does not allow the optical cable 31 to slip out of the tube-shaped member 4 even if it is not closed, since the first tube portion 41 covers the outer periphery of the metal tube 32 as described above. The third slit portion may be substantially closed in the circumferential direction of the third tubular portion 43, or may not be closed in the circumferential direction of the third tubular portion 43 since it is separated from the metal tube 32.

[0060] (First shrink tube and second shrink tube) The terminal structure 21 of the first OPGW and the terminal structure 22 of the second OPGW preferably further have a first shrinkable tube and a second shrinkable tube. In this embodiment, the first shrinkable tube is a first heat shrinkable tube 51. In this embodiment, the second shrinkable tube is a second heat shrinkable tube 52 (FIG. 3). In addition, the first shrinkable tube is a first spiral tube 53 (FIG. 5) and a first cold shrinkable tube, which will be described later. In this embodiment, the second shrinkable tube is a second spiral tube 54 (FIG. 5) and a second cold shrinkable tube, which will be described later. The first and second cold shrinkable tubes are not shown. The first and second heat shrinkable tubes 51 and 52 may be formed of separate members independent of each other. The first and second heat shrinkable tubes 51 and 52 may be formed of a single continuous member.

[0061] The first heat shrink tube 51 covers the outer circumferential surface of the cylindrical member 4 and the outer circumferential surface of the metal tube 32 in a continuous manner. The first heat shrink tube 51 is in close contact with the outer circumferential surface of the cylindrical member 4 and the outer circumferential surface of the metal tube 32. The first heat shrink tube 51 can suppress misalignment of the cylindrical member 4 with respect to the metal tube 32. Therefore, it is easy to insert the multiple tubes 312 into the third cylindrical portion 43 by storing a predetermined number of optical fiber cores 311 in each tube 312. The second heat shrink tube 52 covers the outer circumferential surface of the cylindrical member 4 and the outer circumferential surfaces of the multiple tubes 312 in a continuous manner. The second heat shrink tube 52 is in close contact with the outer circumferential surface of the cylindrical member 4 and the outer circumferential surfaces of the multiple tubes 312. The second heat shrink tube 52 can suppress misalignment of the multiple tubes 312 with respect to the cylindrical member 4. The first heat shrink tube 51 and the second heat shrink tube 52 may partially overlap each other. The first heat shrink tube 51 and the second heat shrink tube 52 are more likely to suppress misalignment of the tubular member 4 with respect to the metal tube 32 and misalignment of the multiple tubes 312 with respect to the tubular member 4 than the first spiral tube 53 and the second spiral tube 54 (both in FIG. 5 ) described below. This is because the first heat shrink tube 51 and the second heat shrink tube 52 are more likely to adhere to the outer circumferential surface of the tubular member 4, the outer circumferential surface of the metal tube 32, and the outer circumferential surfaces of the multiple tubes 312 than the first spiral tube 53 and the second spiral tube 54.

[0062] [Connection] The connection section 6 is formed by connecting together the optical fiber cores 311 of the optical cable 31 drawn out from each terminal structure (FIG. 1). The connection section 6 is housed in a connection box 7.

[0063] [Connection box] The connection box 7 houses the connection portion 6 inside. The connection box 7 houses each terminal structure except for the metal wire 34. That is, the metal tube 32 exposed from the metal wire 34, the cylindrical member 4, the tube 312, the first heat shrink tube 51, and the second heat shrink tube 52 are housed inside. The connection box 7 includes a main body 71 and a lid 72 for opening and closing the inside of the main body 71. In this example, the connection box 7 has a sealed structure formed by fastening the main body 71, which has a rectangular container-like outer shape, and the lid 72 with a plurality of bolts via an O-ring made of silicone rubber. Illustration of the O-ring is omitted.

[0064] [Grip fittings] The storage structure 1 for the OPGW connection portion includes a gripping metal fitting 8 that grips the OPGW 3 on the outside of the connection box 7. The gripping metal fitting 8 includes a pair of plate-shaped gripping members. One of the gripping members is fixed integrally to the outside of the main body 71 with a bolt, and the other gripping member is arranged so that it can be freely attached and detached from the one gripping member. Each gripping member is made of a plate material with a curved center so that when the OPGW 3 is gripped, it covers almost the entire outer periphery of the OPGW 3. The OPGW 3 is gripped by fixing both gripping members with a bolt.

[0065] [Assembly Instructions] The storage structure 1 for the connection portion of the OPGW is assembled through the following steps.

[0066] First, each OPGW 3 is pulled into the junction box 7. The metal wire 34 and metal tube 32 of each OPGW 3 are cut in stages at appropriate positions. This staged cutting exposes the end of the metal tube 32 from the metal wire 34, and exposes the optical cable 31 from the metal tube 32. The exposed end of the metal tube 32 and the optical cable 31 are pulled into the main body 71 of the junction box 7. Then, the end of the metal wire 34 is held by the holding fitting 8 outside the main body 71 of the junction box 7.

[0067] Next, the tubular member 4 is attached from the outer periphery side to the outer periphery of the end of the metal tube 32 and the outer periphery of the optical cable 31 exposed from the metal tube 32. Specifically, the slit 44 is widened, and the first tubular portion 41 is attached to the outer periphery of the end of the metal tube 32, and the second tubular portion 42 and the third tubular portion 43 are attached to the outer periphery of the optical cable 31.

[0068] Next, the first heat shrink tube 51 is brought into close contact with the outer circumferential surface of the tubular member 4 and the outer circumferential surface of the metal tube 32. The first heat shrink tube 51 before shrinking is slid and moved from the tip of the optical cable 31 to a position covering the outer periphery of the tubular member 4 and the outer periphery of the metal tube 32. Then, the first heat shrink tube 51 is heated to shrink it.

[0069] Next, a predetermined number of optical fiber cores 311 are housed in each tube 312. Each tube 312 is slid from the tip of the optical cable 31 to a position where one end of each tube 312 is disposed within the third tubular portion 43.

[0070] Next, the second heat shrink tube 52 is brought into close contact with the outer circumferential surface of the cylindrical member 4 and the outer circumferential surfaces of the plurality of tubes 312. The second heat shrink tube 52 before shrinking is slid and moved from the tip of the optical cable 31 to a position covering the outer periphery of the cylindrical member 4 and the outer periphery of the plurality of tubes 312. Then, the second heat shrink tube 52 is heated to shrink it.

[0071] Next, the optical fiber cores 311 are exposed from each tube 312, and the exposed optical fiber cores 311 are stored one by one in another tube. Then, a third heat shrink tube is brought into close contact with the outer periphery of each tube 312 and the outer periphery of the other tubes. The other tubes and the third heat shrink tube are not shown in the drawings. It is to be noted that the third heat shrink tube does not have to be used.

[0072] Next, the ends of the optical fiber cores 311 of the OPGWs 3 are connected to each other.

[0073] [Action and Effect] The storage structure 1 for the connection part of the OPGW according to this embodiment is provided with the tubular member 4 that can easily center the optical cable 31 relative to the metal tube 32 and can suppress contact of the optical cable 31 with the inner peripheral edge of the end face of the metal tube 32, so that the optical cable 31 is less likely to be damaged. Furthermore, the storage structure 1 for the connection part of the OPGW has excellent productivity because the tubular member 4 can be attached to the metal tube 32 and the optical cable 31 from the outer periphery side of the metal tube 32 and the optical cable 31.

[0074] Second Embodiment [Housing structure for optical fiber composite overhead ground wire (OPGW) connection] A storage structure for a connection portion of an OPGW according to embodiment 2 will be described with reference to Fig. 5. The storage structure for a connection portion of an OPGW according to this embodiment differs from storage structure for a connection portion of an OPGW according to embodiment 1 in that the first and second shrink tubes include a first spiral tube 53 and a second spiral tube 54. The following description will focus on the differences from embodiment 1. Description of the same configuration as embodiment 1 will be omitted.

[0075] [OPGW terminal structure] The first spiral tube 53 and the second spiral tube 54 may be formed as a single continuous member, or may be formed as separate members independent of each other. The first spiral tube 53 covers the outer circumferential surface of the cylindrical member 4 and the outer circumferential surface of the metal tube 32 in a continuous manner, as with the first heat shrinkable tube 51. The second spiral tube 54 covers the outer circumferential surface of the cylindrical member 4 and the outer circumferential surfaces of the multiple tubes 312 in a continuous manner, as with the second heat shrinkable tube 52. The inner diameter of the first spiral tube 53 in a natural state in which no external force is applied is smaller than the outer diameter of the metal tube 32. Therefore, when the first spiral tube 53 is attached to the outer circumferential surface of the cylindrical member 4 and the outer circumferential surface of the metal tube 32, it can tighten the cylindrical member 4 and the metal tube 32. Therefore, the first spiral tube 53 can suppress the positional deviation of the cylindrical member 4 with respect to the metal tube 32. Therefore, it is easy to insert the multiple tubes 312 into the third cylindrical portion 43 by storing a predetermined number of optical fiber cores 311 in each tube 312. The inner diameter of the second spiral tube 54 in its natural state when no external force is acting thereon is smaller than the diameter of the envelope circle of the multiple tubes 312. Therefore, when the second spiral tube 54 is attached to the outer circumferential surface of the tubular member 4 and the outer circumferential surfaces of the multiple tubes 312, the second spiral tube 54 can fasten the tubular member 4 and the multiple tubes 312 together. The second spiral tube 54 can suppress misalignment of the multiple tubes 312 with respect to the tubular member 4.

[0076] [Action and Effect] The storage structure for the connection part of the OPGW according to this embodiment is similar to the storage structure for the connection part of the OPGW according to the first embodiment in that the optical cable 31 is not easily damaged and is excellent in productivity. Furthermore, the storage structure for the connection part of the OPGW according to this embodiment is easier to construct the terminal structure 21 of the first OPGW and the terminal structure of the second OPGW than the storage structure for the connection part of the OPGW according to the first embodiment. This is because the first spiral tube 53 and the second spiral tube 54 are easier to attach to the outer circumferential surface of the cylindrical member 4, the outer circumferential surface of the metal tube 32, and the outer circumferential surfaces of the tubes 312 than the first heat shrink tube 51 and the second heat shrink tube 52. As described above, the first heat shrink tube 51 and the second heat shrink tube 52 are slid from the tip of the optical cable 31 to a predetermined position. In contrast, the first spiral tube 53 and the second spiral tube 54 can be attached from the outer circumferential side of the cylindrical member 4, etc.

[0077] The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0078] 1. Storage structure for OPGW connection 21 First OPGW terminal structure, 22 Second OPGW terminal structure 3 OPGW 31 Optical cable, 311 Optical fiber core, 312 Tube 32 metal tube, 321 inner tube, 322 outer tube 33 Jeri, 34 Metal wire, 341 Bare wire 4 Cylindrical member 41 first cylinder part, 42 second cylinder part, 43 third cylinder part, 44 slit, 442 second slit section 51 first heat shrink tube, 52 second heat shrink tube 53 first spiral tube, 54 second spiral tube 6 Connection 7 Connection box, 71 Main body, 72 Lid 8 Grip fitting

Claims

1. A cylindrical member made of rubber, A first cylindrical portion; A second cylindrical portion continuous with the first cylindrical portion in an axial direction; a slit extending over the entire axial length of the cylindrical member; an inner diameter of the first cylindrical portion corresponds to an outer diameter of a metal tube disposed inside the optical fiber composite overhead ground wire; an inner diameter of the second cylindrical portion is equal to or larger than an outer diameter of the optical cable disposed inside the metal tube and smaller than an inner diameter of the metal tube; The slit has a second slit portion provided in the second cylindrical portion along the axial direction of the cylindrical member, The second slit portion is An outer slit located on an outer periphery of the second cylindrical portion; an inner slit located on the inner periphery of the second cylindrical portion and connected to an end of the outer slit on the inner periphery side, The outer slit is formed to open radially outward of the cylindrical member, The inner slit is substantially closed in the circumferential direction of the second cylindrical portion. Cylindrical member.

2. The tubular member according to claim 1 , wherein the second tubular portion has an axial length of 3 mm or more and 50 mm or less.

3. the cylindrical member has a third cylindrical portion continuous with the second cylindrical portion on an axially opposite side to the first cylindrical portion, The inner diameter of the third cylindrical portion increases in a direction away from the second cylindrical portion, The tubular member according to claim 1 or 2, wherein the slit extends over an entire axial length of the third tubular portion.

4. The tubular member according to claim 3 , wherein an inclination angle of an inner circumferential surface of the third tubular portion with respect to an axis of the third tubular portion is equal to or greater than 1° and equal to or less than 45°.

5. 5. The tubular member according to claim 1, wherein the material of the tubular member includes at least one selected from the group consisting of urethane rubber, silicone rubber, chloroprene rubber, and ethylene propylene rubber.

6. an optical fiber composite overhead ground wire including an optical cable, a metal tube for housing the optical cable, and a metal wire provided on an outer periphery of the metal tube; a cylindrical member that covers an outer periphery of the end of the metal tube and an outer periphery of the optical cable drawn out from the end of the metal tube in a continuous manner, The cylindrical member is a cylindrical member according to any one of claims 1 to 5, the first cylindrical portion of the cylindrical member covers an outer periphery of an end portion of the metal pipe, The second tubular portion of the tubular member covers an outer periphery of the optical cable pulled out from the end of the metal tube. Terminal structure of optical fiber composite overhead ground wire.

7. The metal tube has an inner tube and an outer tube provided on the inside and outside, the inner tube is constructed from stainless steel; 7. The terminal structure of claim 6, wherein the outer tube comprises aluminum.

8. 8. The terminal structure of an optical fiber composite overhead ground wire according to claim 6, further comprising a gel filled between said metal tube and said optical cable.

9. The optical cable includes: A plurality of optical fiber cores; 9. The terminal structure of a composite optical fiber ground wire according to claim 6, further comprising a plurality of tubes each containing a predetermined number of the optical fiber core wires.

10. An optical cable having a plurality of optical fiber cores and a plurality of tubes in which the plurality of optical fiber cores are housed in predetermined numbers, a metal tube in which the optical cable is housed, and an optical fiber composite overhead ground wire having a metal wire provided on the outer periphery of the metal tube; a cylindrical member that covers an outer periphery of the end of the metal tube and an outer periphery of the optical cable drawn out from the end of the metal tube; a first shrink tube continuously covering an outer circumferential surface of the cylindrical member and an outer circumferential surface of the metal tube; a second shrink tube that covers the outer circumferential surface of the cylindrical member and the outer circumferential surfaces of the plurality of tubes in a continuous manner, The cylindrical member is made of rubber, The cylindrical member is A first cylindrical portion; A second cylindrical portion continuous with the first cylindrical portion in an axial direction; a slit extending over the entire axial length of the cylindrical member; an inner diameter of the first cylindrical portion corresponds to an outer diameter of the metal tube; an inner diameter of the second cylindrical portion is equal to or larger than an outer diameter of the optical cable and smaller than an inner diameter of the metal tube; A second slit portion provided in the second cylindrical portion among the slits is substantially closed in a circumferential direction of the second cylindrical portion, the first cylindrical portion of the cylindrical member covers an outer periphery of an end portion of the metal pipe, The second tubular portion of the tubular member covers an outer periphery of the optical cable pulled out from the end of the metal tube. Terminal structure of optical fiber composite overhead ground wire.

11. A terminal structure of a first optical fiber composite overhead ground wire; a termination structure of a second optical fiber composite overhead ground wire; a connection portion that connects the optical cables drawn out from each of the terminal structures; a connection box that houses the connection portion, Each of the terminal structures is a terminal structure of the optical fiber composite overhead ground wire according to any one of claims 6 to 10. A storage structure for the connection part of an optical fiber composite overhead ground wire.

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