JP2002147660A - Double-layer protective pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resisting double-layer protective pipe capable of protecting a communication line to prevent the impairment of its function even in the thermal disaster such as the fire or the like. SOLUTION: This double-layer protective pipe has an inner pipe 3 capable of accommodating an optical fiber 1, and a heat-resisting outer pipe 4 covering the inner pipe 3, and an opening and closing valve 7 and a conducting tube 12 are mounted for allowing the water to flow into a space part 5 formed between the inner pipe 3 and the outer pipe 4. A cooling control system R is formed by mounting a control device 9 for opening the opening and closing valve 7 by a driving unit 8 to circulate the water into the space part 5 in a small zone s having a heat sensor 6, when the heat of a temperature higher than a predetermined temperature is sensed by the heat sensor 6 mounted on the outer pipe 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer protective tube having an inner tube capable of accommodating communication strips such as an optical fiber, a telephone line, and an information communication line, and an outer tube covering the inner tube. TECHNICAL FIELD The present invention relates to a technology for protecting a communication strip from heat and maintaining an information transmission function even when a fire or the like occurs in a wiring portion of a multilayer protective tube.

[0002]

2. Description of the Related Art A multi-layer protective tube of this kind is disclosed in
No. 3,606,643, a structure including an inner tube accommodating an optical fiber and a metallic outer tube having a bellows shape, and the inside of the inner tube is placed under an atmosphere of vacuum, oil, or dry gas. Are known. Also, Japanese Unexamined Patent Publication No.
In Japanese Patent Application Laid-Open No. 7-105706, the airtight
A multilayer structure in which an optical fiber is closely covered with a secondary metal coating layer and covered with a soft metal secondary metal coating layer and an outermost metal pipe, or disclosed in JP-A-9-90184. As in the case of a multi-layer structure, there is known a multi-layer structure in which a plurality of optical fiber units each including an optical fiber inside a polyethylene pipe via a buffer layer are accommodated in a protective tube.

[0003]

The former prior art is intended to eliminate the disadvantage that it is weak to temperature changes or cannot be used in a humid place. It is intended to solve problems such as difficulty in completely sealing, low adhesion strength with an optical fiber, and poor heat resistance. The latter prior art has improved the workability at the time of laying the pipeline by reducing the frictional resistance of the resin layer around the optical fiber, and greatly improved the insertion distance and the insertion speed of the optical fiber. Things.

[0004] In recent years, it has become necessary to provide a protective tube through a communication strip such as an optical fiber in a closed space in multiple layers (multilayering) in order to further protect against external disturbance. I have. For example, the IT revolution is called "optical fiber cable"
Have been laid nationwide, and are laid underground on their side roads regardless of national roads or local roads. In addition to the roads, they must be laid in bridges, tunnels, underground shopping centers, and buildings.

[0005] A communication strip such as an optical fiber is a lifeline of information transmission, and cannot be disconnected even in the event of a natural disaster such as an earthquake or a typhoon or a fire. for that reason,
Various multi-layer pipes as described above have been prepared, but in reality, no pipes capable of coping with high heat due to fire or the like have been proposed. That is, when a building fire, a tunnel fire, or a fire caused by an earthquake occurs, the effect of high heat is less likely to reach the communication strip such as an optical fiber in the conventional multi-layer protective tube than in the single-layer protective tube. However, since no measures were taken against heat, there was a possibility that the communication strip could be broken by the influence of heat.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-layer protective tube having heat resistance so that the function of a communication strip can be protected even if a thermal disaster such as a fire occurs. It is in.

[0007]

Means for Solving the Problems [Configuration and Function] Claim 1
Is a multi-layered protective tube comprising an inner tube capable of accommodating a communication strip and an outer tube having heat resistance covering the inner tube, and formed between the inner tube and the outer tube. The fluid is configured to be able to flow through the space.

According to the first aspect of the present invention, (a) Since the outer tube has heat resistance, the outer tube is not damaged by melting or deforming even by high heat due to a fire, etc. Can be protected from spreading to the inner tube. (B) Since the fluid can flow through the space formed between the inner pipe and the outer pipe, the outer pipe can be cooled from the inside and the inner pipe can be cooled from the outside by the flow of the fluid. This makes it possible to release the heat of the outer tube, which has become hot due to a fire or the like, and make it difficult for the heat of the outer tube to be transmitted to the inner tube.

According to a second aspect of the present invention, in the configuration of the first aspect, a heat sensor is provided on the outer tube, and when the heat sensor detects heat of a predetermined temperature or more, the space between the inner tube and the outer tube. A control means for flowing a fluid to the section is provided.

According to the second aspect of the present invention, the space formed between the inner tube and the outer tube only when the outer tube becomes hotter than normal due to the action of the heat sensor and the control means. And the above-mentioned action (b) is obtained by flowing a fluid through
Normally, when the heat sensing sensor does not perform the sensing operation, the fluid circulation operation can be omitted, and unnecessary fluid flowing operation can be eliminated.

A third aspect of the present invention is characterized in that, in the configuration of the second aspect, the heat sensing sensor and the control means are arranged for each predetermined section in the longitudinal direction of the outer tube.

According to the third aspect of the present invention, a series of control operations for flowing a cooling fluid between the inner tube and the outer tube by detecting heat of a predetermined temperature abnormality acting on the outer tube is performed in a limited section. This can be performed every time, so that unnecessary control operation and fluid can be saved as compared with the case where the fluid flows through the entire multi-layer protective tube.

According to a fourth aspect of the present invention, in the first to third aspects, the communication strip is an optical fiber, and the fluid is a nonflammable fluid.

According to the fourth aspect of the present invention, since the optical fiber is used as the communication strip, a large amount of accurate information communication can be performed at high speed, and the fluid flowing between the inner pipe and the outer pipe is made nonflammable. Since the fluid does not burn due to the high heat of the outer tube due to a severe fire or the like, the above operation (b) can be reliably exhibited.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the non-combustible fluid is water.

According to the fifth aspect of the present invention, since the non-combustible fluid is water, a fluid source (water source) such as a water guide pipe, a water storage tank, or a pond passing therethrough can be relatively easily secured.
Cooling control equipment flowing between the fluid inner tube and the outer tube can be constructed relatively simply and at low cost.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional structure of an optical communication cable A using a multilayer protective tube a having a double-tube structure. 2 is an optical fiber 1 covered with a synthetic resin material.
3 is an optical fiber unit, 3 is an inner tube made of PE (polyethylene), 4 is a stainless steel (SUS304 etc.)
The annular space 5 between the inner pipe 3 and the outer pipe 4 is used as a water passage.

FIG. 2 shows a cooling control system (an example of control means) R using the optical communication cable A shown in FIG. The system R is embedded in a heat sensing sensor 6, an on-off valve 7, an on-off drive unit 8 for controlling the on-off operation of the on-off valve 7, a control device 9, and a nearby ground 10 installed at a plurality of locations of the outer pipe 4. The water main pipe 11 and the on-off valve 7 communicate with each other.

In the multi-layer protective tube a, ring-shaped partitions 13 for blocking the space 5 between the outer tube 4 and the inner tube 3 are arranged at regular intervals in the longitudinal direction of the pipe. The optical communication cable A is divided into a number of small zones (an example of a predetermined section) s. Further, a cooling control system R which operates independently of each other is provided for each of the small zones s separated by the pair of partitions 13. Incidentally, one set of each component constituting the cooling control system R is provided for each small zone s.

The control operation of the cooling control system R will be described. When any one of the plurality of heat sensors 6 performs a sensing operation at a temperature exceeding a predetermined temperature, the on-off valve 7 which has been closed until then is turned on and off. Is opened, and when the sensing operation of all the heat sensing sensors 6 and 6 is stopped, the opened on-off valve 7 is closed by the on-off drive unit 8.

When the on-off valve 7 is opened, the water in the water main 11 is introduced into the section 5 through the water introduction pipe 12 and the inlet pipe 14 by the pressure, and flows through the space 5 in the longitudinal direction of the pipe.
It becomes drained through the outlet pipe 15. Therefore,
When the outer tube 4 is exposed to high heat due to a fire or the like and its temperature rises above a predetermined value, water is automatically flown into the space 5 to cool the outer tube 4 and also suppress the temperature rise of the inner tube 3. Therefore, the optical fiber unit 2 in the inner tube 3 can be protected from damage due to high heat.

For reference, the inner tube 3 is a PE tube having an outer diameter of 165.2 mm and containing six optical fiber units 2. The outer tube 4 of stainless steel has an outer diameter of 216.3 mm and a wall thickness of 8 mm. It is. And the outer tube 4 is then
In an experiment of heating from a distance of m with a gas burner at 800 degrees Celsius, it was confirmed that after 2 minutes, the heat sensing sensor 6 was activated to start water cooling and the outer tube 4 was cooled well. At that time, the temperature of the optical fiber unit 2 rose by about 5 ° C., and it was confirmed that there was no problem in use.

The following is a reference. Water is required to make the multi-layer protective tube a a fire-resistant structure, and the following conditions 1 to 3 are required to configure the cooling control system R described above. 1.
There is a water source nearby, such as a nearby water main that can be branched and secured as a water source. 2. There must be a power source, such as the ability to distribute power from nearby wires. 3. A pipe that satisfies the following conditions is required.

The pipe has a double structure of an inner pipe 3 and an outer pipe 4,
The inner tube 3 may be made of resin. The outer pipe 4 cannot withstand heat (fire) from the outside, so it is impossible with a resin pipe.
A metal tube having heat resistance is desirable. Considering durability (such as maintenance after rust), a stainless steel pipe is preferable. Further, both the inner and outer tubes 3 and 4 are required to have a sealing property (sealing property). When the inner pipe 3 is a resin pipe, it is not preferable to use welding as a joining means of the outer pipe 4, and it is desirable to use a flange or a mechanical joint.

When the effective inner diameter of the inner tube 3 is determined to be 100 mm, the effective inner diameter of the outer tube 4 is 150 mm in consideration of the cross-sectional area of the pipe (tube) and the volume (dimension) at the time of attachment.
Can respond. When the inner tube 3 is a resin tube, if the thermosoftening temperature of the thermoplastic resin is set to 70 degrees Celsius and the performance limit temperature of the optical fiber 1 is set to 80 degrees Celsius, the water pressure at the time of passing water is taken into consideration. Then, considering the safety factor, the water pressure and the like are calculated and controlled so that the temperature of the passed water is 50 degrees Celsius or less.

[Alternative Embodiment] The multilayer protective tube a and the optical communication cable A may have the following structures.
The inner tube 3 is composed of an FRP (fiber reinforced plastic) tube having an outer diameter of 150 mm and a thickness of 6 mm, and the outer tube 4 has an outer diameter of 21 mm.
A multi-layer protective tube a made of a gas steel tube having a thickness of 6 mm and a thickness of 8 mm. An optical fiber unit 2 having the same structure as in FIG.
Optical communication cable A containing

As shown in FIG. 3, a cooling control system R having a water storage tank 16 and a water pump 17 connected to the control device 9 may be used instead of the water main pipe 11 under internal pressure. In this case, the water supply pump 17 is driven at the same time as the on-off valve 7 is opened by the heat sensing operation, and the drive of the water supply pump 17 is stopped at the same time as the on-off valve 7 is closed.

In the structure shown in FIG. 3, in the experiment in which the outer tube 4 is heated by a gas burner at 800 degrees Celsius from a position 30 cm away from the outer tube 4, the heat sensing sensor 6 senses and operates after 2 minutes to supply water. It started, and it was confirmed that the surface of the outer tube 4 was cooled well by the water flowing for 3 minutes.
Also, the temperature rise of the optical fiber unit 2 at that time is also 10
Degree, and there was no practical problem.

When the water tank 16 is at a sufficiently high position, first, the on-off valve 7 is opened to introduce water into the space 5 by gravity. (When the temperature does not decrease), it is also possible to control to increase the cooling performance by driving the water supply pump 17.

The water source is branched from the existing water pipe to secure a water source.
A structure may be adopted in which a fire detector is set as a heat sensor 6 in a tunnel or a cave, and when sensing operation is performed, an electromagnetic valve is opened to flow water to cool the inner pipe 3 and the outer pipe 4. In this case, if the lower portion of the outer tube 4 is machined so that the sprinkler can be freely attached, the fire extinguishing function can be provided locally.

The resin tube usable as the inner tube 3 is FRP
There are tubes, VP tubes, and PE tubes. FRP pipe: The most heat-resistant among resin pipes, and piping (connection) is relatively easy. In terms of price, it is expensive among resin tubes. -VP pipes: There are many joints among resin pipes, and the price is low. Watertightness is also reliable with a common bonding method (provided in waterworks). -PE pipe: a pipe that is relatively soft as a characteristic of resin and has some flexibility and is easy to handle. Bonding or joining with joints. Metal pipes that can be used as the outer pipe 4 include steel pipes, coated steel pipes, and SUS pipes.・ Steel (iron) tubes: These are representative tubes of metal tubes and are relatively inexpensive, but under the conditions of use for fire resistance purposes this time, there are difficulties due to problems such as rust. -Coated steel pipe: A steel pipe is coated, but there are many problems such as coating of the machined surface. The price is also expensive, and seems to be unsuitable for the conditions of use this time. -SUS tube: It is resistant to rust and relatively lightweight, and seems to be the most suitable material for the present invention. However, it is relatively expensive in terms of price.

As the fluid, various substances other than water, such as low-temperature liquefied gas, inert gas such as nitrogen gas, lake water, seawater, hydraulic oil, cooling water, steam, etc., can be used. Further, when the length of the multilayer protective tube a is short, the whole may be controlled by one cooling control system R without being divided into small zones s as shown in FIGS. Further, one or three or more heat sensing sensors 6 may be provided in each small zone s. If the number of sensors is small, it is economical, and if the number of sensors is large, accurate cooling control can be performed.

[0033]

According to the first aspect of the present invention, the inner pipe can be cooled while preventing the outer pipe from being overheated even under a high heat condition such as a fire, by the actions (a) and (b). In other words, the communication strip housed in the inner pipe can be provided as one having excellent fire resistance performance that can function reliably without causing damage due to heat.

In the multi-layer protective tube according to the second aspect, the above-mentioned effect according to the first aspect has been obtained while the economical operation without unnecessary fluid flowing operation is achieved.

In the multi-layer protective tube according to the third aspect, it is possible to save unnecessary control operations and the fluid itself, and it is possible to enhance the economical effect of the second aspect.

In the multi-layer protective tube according to the fourth aspect of the present invention, any one of the above-mentioned effects according to the configuration of the first to third aspects is exhibited, and an excellent communication strip with a high speed and a large amount of information by an optical fiber is provided in the inner tube. A reliable one that can be protected by reliable fire resistance by flowing a nonflammable fluid between the outer tube and the outer tube.

The multi-layer protective tube according to the fifth aspect has the above-mentioned effect of the configuration of the fourth aspect, and also uses a water-based fluid to make the cooling control system (equipment) relatively simple or inexpensive. There are practical advantages that can be configured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a communication strip.

FIG. 2 is a system diagram showing a structure of a cooling control system.

FIG. 3 is a system diagram showing another structure of the cooling control system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Communication article 3 Inner tube 4 Outer tube 5 Space 6 Heat sensing sensor R Control means

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H02G 1/06 311 H02G 9/00 A 9/00 G02B 6/00 351

Claims (5)

[Claims] An inner tube capable of accommodating a communication strip, an outer tube having heat resistance covering the inner tube, and a space formed between the inner tube and the outer tube. Multi-layer protective tube configured to allow fluid to flow. 2. The multi-purpose device according to claim 1, wherein a heat sensing sensor is provided on the outer tube, and a control means for flowing the fluid through the space when the heat sensing sensor senses heat of a predetermined temperature or higher is provided. Layer protection tube. 3. The multi-layer protective tube according to claim 2, wherein the control means is arranged for each predetermined section in the longitudinal direction of the outer tube. 4. The multi-layer protective tube according to claim 1, wherein the communication strip is an optical fiber, and the fluid is a nonflammable fluid. 5. The multi-layer protective tube according to claim 4, wherein the nonflammable fluid is water.