JPH06201923A - Air blow fiber line and its connector - Google Patents

Abstract

PURPOSE:To provide the air blown fiber line for limiting water intrusion within the section even in the case water is intruded into a tube due to an unexpected cable disconnection accident, etc., and its connector. CONSTITUTION:In the air blown fiber line for constituting an optical fiber unit 1 by feeding forcibly air into a tube 2, the air blown fiber line and its connector are constituted so that the inside diameter of a part in the lengthwise direction of the tube 2 is varied reversibly from a state of the time of forcible feeding to the optical fiber unit to a state of coming into soft contact with the outside peripheral surface of the optical fiber unit 1 subjected to forcible feeding, and water running between the tube 2 and the optical fiber unit 1 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air blown optical fiber line constructed by pneumatically feeding an optical fiber unit into a tube and a connector for connecting or fixing the ends of the tubes.

[0002]

2. Description of the Related Art In recent years, as an optical fiber laying technique, an air blown fiber has been constructed in which a plastic tube or a cable in which a plurality of tubes are assembled is laid in advance, and then an optical fiber unit is pneumatically fed into these tubes. A construction method has been devised, and it is rapidly spreading as an indoor wiring system in buildings, etc. and a facility wiring system because of the following features. (1) Even if an initial investment is not made in advance for an optical fiber reserve, it is possible to freely add an optical fiber or upgrade to a new optical fiber of higher performance, etc., by providing a spare tube. (2) Even if the length of the cable is short, if the tubes are connected in series with the airtight connector in advance, the optical fiber unit can be pumped in series over a long distance.
The number of optical fiber connection points can be reduced. (3) The installation route can be switched and dropped freely by opening and closing the tube connector. (4) If a connector is provided on the tube in advance in a portion where branch connection is expected in the future, branch connection of the optical fiber can be easily performed as needed in the future.

FIG. 4 is a cross-sectional view of an example of an optical fiber unit used in the above-mentioned air blown fiber construction method. As shown in the drawing, a plurality of optical fiber element wires (diameter about 0.25 mm) 11 having a coating layer of UV resin or the like on an optical fiber and a rip cord 12 are twisted together, and a primary coating of synthetic resin is made. 13 is further provided, and a secondary coating 14 such as foamed plastic having a light weight and a high air resistance is further provided thereon. The outer diameter is about 2 mmφ.

FIG. 5 shows an example of the structure of the tube cable 20, which is a cross-sectional view of the tube cable having a metal corrugated armor for direct embedding. As shown in the drawing, a central tension member 21 having a plastic covering layer on the outer periphery of the strength member is provided.
A plurality of tubes 22 with a smooth inner surface made of plastic such as polyethylene having an inner diameter of about 8 mmφ are twisted around the circumference of, and a plastic sheath 22 of polyethylene, vinyl chloride or the like is further laid on it, and a metal corrugate of aluminum or the like is further provided on it. The sheath 23 and a plastic anticorrosion layer 23 are sequentially applied.

[0005]

Conventionally, the air blown fiber construction method has been used as a construction method for indoor wiring such as in a building or wiring in a facility, directly in seawater, running water, sewage, etc. It has been used mainly in environments that are not likely to be exposed.

Recently, however, there has been a demand for the advantages of the air blown fiber construction method to be applied to a wider area of the outdoor communication network, and the tube cable for the air blown fiber is used in a more severe outdoor environment than ever before. It has become necessary to lay over long distances. In particular, in the case of a direct burying type tube cable using a metal corrugated sheath, etc., after installation, if the cable is cut due to an unexpected accident and seawater, running water, sewage, etc. enter the cable,
With tube cables, seawater, running water, sewage, etc. are more likely to run in the longitudinal direction than ordinary optical cables, so that the problem that damage is likely to spread has arisen.

On the other hand, in the case of the air blown fiber construction method, since it is difficult to make the inside of the tube waterproof in the longitudinal direction, the connecting portion between tubes or the tube provided in the closure for connecting the cable. A technique to stop the water running in the longitudinal direction at the terminal end of the is required.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides an air blown fiber line and a connector for the same which solve the above-mentioned problems, and is characterized by an air blower constructed by pneumatically feeding an optical fiber unit into a tube. In the fiber optic line, the inner diameter of a part of the length of the tube is
An air blown fiber line configured to prevent water running between the tube and the optical fiber unit, which reversibly changes from the state when the optical fiber unit is being pumped to the state where it is in soft contact with the outer peripheral surface of the pumped optical fiber unit. is there.

A second feature of the present invention is that the minimum inner diameter of the connector for tube interconnection or terminal fixing is formed of an elastic body, and the minimum inner diameter of the connector is operated by operating a mechanism provided outside the connector. The portion is in soft contact with the outer peripheral surface of the optical fiber unit, and is in the connector of the air blown fiber line configured to prevent running water between the tube and the optical fiber unit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial vertical sectional view of a concrete example of an air blown fiber line of the present invention. FIG. 1 (a) is a state diagram (referred to as state 1) when an optical fiber unit is pumped, and FIG. The state diagram after pressure feeding (referred to as state 2) is shown. In the drawings, 1 is an optical fiber unit as shown in FIG. 4, for example, 2 is a tube having a smooth inner surface made of plastic such as polyethylene, and its inner diameter is constant. Reference numeral 3 is a variable inner diameter portion of the tube.

In the state 1, the inner diameter varying portion 3 of the tube has the same inner diameter as the tube 2, but in the state 2 in which the optical fiber unit 1 is pneumatically fed into the tube 2, the inner diameter varying portion 3 is formed. Reversibly changes to a state of being in soft contact with the outer peripheral surface of the optical fiber unit 1, thereby preventing water running between the tube 2 and the optical fiber 1.

FIG. 2 is a vertical sectional view of a concrete example of the connector portion in the air blown fiber line of the present invention.
Shows state 1 and FIG. 2B shows state 2. In the drawing,
4 is an elastic tube having a uniform inner diameter b and an outer diameter of a square distribution type in a free state, 6, 7 and 8 are holders for holding the elastic tube 4 having a higher elastic modulus than the elastic tube 4, The holder 6 is located between one end of the elastic tube 4 and the tube 2, and the holder 7 is located on the left outer circumference of the elastic tube 4 and is engaged with the holder 6. The holder 8 is located on the outer circumference of the right side of the elastic tube 4, covers the end of the elastic tube 4 and extends on the right side tube 2. A coupling nut 5 is supported by the holders 6, 7 and 8 and is rotatable with respect to the holder 7, connected to a screw screw 9 or a bayonet lock mechanism with respect to the holder 8, and external to the connector body. It is exposed to and can be operated from outside.

FIG. 3 is a vertical sectional view of another embodiment of the connector portion in the air blown fiber line of the present invention.
(A) shows the state 1, and FIG. 3 (b) shows the state 2. In the drawings, the same reference numerals as those in FIG. 2 represent the same parts. In the drawing, 31 is an elastic collet chuck located on the optical fiber unit 1, 32 is a higher elastic modulus than the elastic collet chuck 31, and the elastic collet chuck 31
The coupling nut 5 is supported by the holders 6, 8 and the guide ring 32 by the guide ring located on the taper portion of the outer periphery of the guide ring 32 and is rotatable with respect to the guide ring 32.
The holder 8 is connected by a screw screw 9 or a bayonet lock mechanism, is exposed to the outside of the connector body, and can be operated from the outside.

The holder of the above embodiment may be used in combination with a release ring which is a known technique for removing a tube. Further, the elastic collet chuck 10, the holder 8 and the holder 6 and the guide ring 32 in FIG. 3 may be integrated parts or parts integrated by press fitting.
Further, a known fixing mechanism such as a bayonet locking mechanism may be used instead of the screw screw 9 in FIGS. 2 and 3.
The elastic tube 4 or the elastic collet chuck 31 may be entirely made of an elastic body such as plastic, or a part thereof may be a hard body such as metal or ceramic and only the movable portion may be an elastic body.

2 and 3, in the air blown fiber construction method, air leakage during pressure feeding of the optical fiber is prevented, so that gas can be communicated between the tubes without leaking from tube to tube. It is preferable to provide an O-ring or packing between the coupling nut and the holder, etc., if necessary.

[0016]

In the line shown in FIG. 1, the inner diameter D of the tube inner diameter varying portion 3 is set to 0.9b ≦ D ≦ 1.1b, and in this state, the optical fiber unit 1 is pneumatically fed into the tubes 2 and 3 and installed. Yes (state 1). After laying, the inner diameter D of the tube inner diameter varying portion 3 is set to 0.7a ≦ D ≦ a (state 2). In this state, a part of the air blown fiber line was destroyed,
Even when water or the like enters the tube 2, the damage caused by water infiltration is limited to only one section sandwiched by the tube inner diameter varying portion 3.

In the connector portion shown in FIG. 2, by rotating the coupling nut 5 in a direction separating from the holder 8, the elastic tube 4 has its minimum inner diameter portion having a diameter Dmin of 0.9b≤Dmin. ≦ 1.1b (FIG. 2, a) In this state, the optical fiber unit 1 can be pressure-fed.

After the optical fiber unit 1 is pressure-fed into the tube 2, the coupling nut 5 is rotated toward the holder 8 to press the elastic tube 4 by the holders 6, 7 and 8. The diameter Dmin of the minimum inner diameter portion of the elastic tube 4 is 0.7a≤Dmin≤a, and the outer surface of the optical fiber unit 1 can be softly contacted at this portion. (Fig. 2, b). In this state,
By using the optical cable, water running between the optical fiber unit 1 and the tube 2 can be stopped at the connector portion even if water is flooded into the tube 2 due to cutting of the optical cable due to an accident.

In the connector portion shown in FIG. 3, the coupling ring 5 is rotated in the direction separating from the holder 8 so that the guide ring 32 is elastic collet chuck.
Retreat to 31. Then, the elastic collet chuck 31
The elasticity of the elastic collet chuck 31 increases the inner diameter of the tip of the elastic collet chuck 31 to be substantially the same as the inner diameter of the tube 2 (FIG. 3, a). In this state, the optical fiber unit 1 can be pressure-fed.

After the optical fiber unit 1 is pressure-fed into the tube 2, the coupling nut 5 is rotated toward the holder 8 so that the guide ring 32 is rotated.
Moves forward with respect to the elastic collet chuck 31. As a result, the inner diameter of the elastic collet chuck 31 becomes smaller, and the elastic collet chuck 31 can softly contact the outer peripheral surface of the optical fiber unit 1 at this portion. (Fig. 3, b). By using the optical cable in this state, water running between the optical fiber unit 1 and the tube 2 can be stopped at the connector portion even if water is flooded into the tube 2 due to cutting of the optical cable due to an accident. .

[0021]

[Experimental Example 1] Three polyethylene tubes (inner diameter: 6 mmφ, outer diameter: 8 mmφ) having lengths of 250 m, 500 m, and 250 m were connected in this order as shown in FIG. At this time, prepare 4 silicon tubes each with a minimum inner diameter of Table 1 as a joint to be used for the connection part, and attach them to both ends of the connection part and the series of tubes, and have an outer diameter of 2 mm.
A series of pressure-feeding experiments of 1 km of 6-fiber optical fiber unit of φ were conducted. The results are shown in Table 1.

[0022]

[Table 1]

Next, 100 m of a single-mode fiber 6-core optical fiber unit having an outer diameter of 2 mmφ is pressure-fed to one polyethylene tube having a single length of 100 m (inner diameter of 6 mmφ, outer diameter of 8 mmφ), and the tube at one end (A end) of the tube is fed. Install the silicon tube whose minimum inner diameter is shown in Table 2 between the optical fiber unit and the optical fiber unit.
Water pressure of ² kg / cm ² was applied to the end), and water leakage from the A end was observed. In addition, the change in transmission loss of the optical fiber before and after mounting the silicon tube was recorded. The results are shown in Table 2.

[0024]

[Table 2]

[0025]

[Experimental Example 2] Silicon rubber is used as the elastic tube 4 in FIG. 2, and brass is used in which the coupling nut 5 and the holders 6, 7 and 8 are nickel-plated, and between the coupling nut 5 and the holder 7 and between the coupling nut 5 and the holder 7. A sample connector 1 having an O-ring between 8 was prototyped.

The coupling nut 5 of the sample 1 is brought into the state shown in FIG. 2 (a), a polyethylene tube having an inner diameter of 6 mmφ and an outer diameter of 8 mmφ is connected to both ends, and an airtight stopper is attached to one end (A end) of the attached polyethylene tube. The other end (B
End), connect a compressor via a pressure gauge and a sealing connector, and let compressed air of 6 kg / cm ² flow from the B end into a polyethylene tube, and after the pressure stabilizes, seal the B end side for 1 minute. As a result of being left as it is, no pressure drop was observed.

Also, five polyethylene tubes each having a single length of 200 m (inner diameter 6 mmφ, outer diameter 8 mmφ) were serially connected by the connectors of sample 1, and the connectors of sample 1 were attached to the ends of the tubes at both ends. As a result of performing a series of pressure-feeding experiments on a 1-km 6-fiber optical fiber unit having an outer diameter of 2 mmφ with the coupling nut in the state shown in FIG. 2A, it was possible to pressure-feed a 1-km optical fiber unit.

Next, the connector of sample 1 was connected to one end (end A) of a single length 100 m polyethylene tube (inner diameter 6 mmφ, outer diameter 8 mmφ), and a coupling nut was attached as shown in FIG.
In the state of (a), 100 m of 6-core optical fiber unit with an outer diameter of 2 mmφ is pressure-fed, and in this state the coupling nut is
In the state of (b), the other end of the polyethylene tube (B
Water pressure of ² kg / mm ² was applied to the end), and water leakage was observed from the end A. No water leakage was observed.

[0029]

[Experimental Example 3] Silicone rubber is used for the elastic collet chuck 31 shown in FIG. 3, polyarylate is used for the guide ring 32, and nickel plated brass is used for the coupling nut 5 and holders 6 and 8, and the coupling nut 5 and the holder are used. 6 and a sample 2 of a connector in which an O-ring was provided between the coupling nut 5 and the holder 8 was manufactured.

The coupling nut 5 of this sample 2 is brought into the state shown in FIG. 3 (a), a polyethylene tube having an inner diameter of 6 mmφ and an outer diameter of 8 mmφ is attached to both ends, and one end (A end) of the attached polyethylene tube is hermetically sealed. , Connect the compressor to the other end (B end) of the polyethylene tube via a pressure gauge and a sealing connector, and from the B end 6 kg / c
As a result of allowing compressed air of m ² to flow through the polyethylene tube and stabilizing the pressure, airtightly sealing the B end side and leaving it for 1 minute or more, no pressure drop was observed.

Also, five polyethylene tubes (inner diameter 6 mmφ, outer diameter 8 mmφ) having a single length of 200 m are serially connected by the connectors of sample 2, and the connectors of sample 2 are attached to the polyethylene tube terminals at both ends. As a result of carrying out a series of pressure-feeding experiments of a 1-km 6-fiber optical fiber unit having an outer diameter of 2 mmφ with the coupling nut of Fig. 3 (a), it was possible to pressure-feed a 1-km optical fiber unit.

Next, the connector of Sample 2 was connected to one end (end A) of a single length 100 m polyethylene tube (inner diameter 6 mmφ, outer diameter 8 mmφ), and a coupling nut was attached as shown in FIG.
In the state of (a), 100 m of 6-core optical fiber unit with an outer diameter of 2 mmφ is pressure-fed, and in this state, the coupling nut is in the state of FIG. 3 (b) and 2 kg / cm ^{2 is} added to the other end (B end) of the polyethylene tube. No water leakage was observed as a result of observing the water leakage at the end A by applying the water pressure.

[0033]

As described above, according to the air blown fiber line and its connector of the present invention, even if seawater, sewage or the like infiltrate into the tube due to an accidental cable disconnection, etc. The spread can be limited to the section where the accident occurred. Therefore, in an area where there is a high probability of accidental cable cutting accidents, damage can be minimized by setting the connector installation interval short beforehand.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a specific example of an air blown fiber line of the present invention, FIG. 1 (a) is a state diagram during optical fiber unit pumping, and FIG. 1 (b) is a state after optical fiber unit pumping. It is a figure.

FIG. 2 is a vertical cross-sectional view of a specific example of a connector portion in an air blown fiber line of the present invention, FIG. 2 (a) is a state diagram during optical fiber unit pumping, and FIG. 2 (b) is a diagram after optical fiber unit pumping. It is a state diagram.

FIG. 3 is a vertical cross-sectional view of a specific example of a connector portion in an air blown fiber line of the present invention, FIG. 3 (a) is a state diagram during optical fiber unit pressure feeding, and FIG. 3 (b) is after optical fiber unit pressure feeding. It is a state diagram.

FIG. 4 is a cross-sectional view of an example of an optical fiber unit used in the air blown fiber method.

FIG. 5 is a cross-sectional view of a tube cable in which a metal corrugated armor for direct embedding is applied, which is an example of the structure of the tube cable.

[Explanation of symbols]

 1 Optical fiber unit 2 Tube 3 Tube inner diameter variable part 4 Elastic tube 5 Coupling nut 6 Holder 7 Holder 8 Holder 9 Screw screw 31 Elastic collet chuck 32 Guide ring

Claims (3)

[Claims] 1. An air blown fiber line constructed by pneumatically feeding an optical fiber unit into a tube,
The inner diameter of a part of the lengthwise direction of the tube reversibly changes from the state at the time of pumping the optical fiber unit to the state of being softly in contact with the outer peripheral surface of the pumped optical fiber unit, and the water running between the tube and the optical fiber unit An air blown fiber line characterized by being configured to prevent the above. 2. An air blown fiber line constructed by pneumatically feeding an optical fiber unit into a tube,
The minimum inner diameter portion of the connector for interconnecting or terminating the tube is formed of an elastic body, and the minimum inner diameter portion of the connector is softly and closely attached to the outer peripheral surface of the optical fiber unit by operating a mechanism provided outside the connector, An air blown fiber line connector, which is configured to prevent water running between the tube and the optical fiber unit. 3. An elastic collet chuck is used as a means for changing the minimum inside diameter of the connector, and the tip of the elastic collet chuck advances in the guide ring by operating a guide ring provided outside the connector. The air blown fiber line connector according to claim 2, wherein the outer diameter of the tip of the elastic collet chuck is reduced, and the tip of the elastic collet chuck is in soft contact with the outer peripheral surface of the optical fiber unit.