JPH0738886Y2 - Optical fiber cable laying conduit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a conduit for laying an optical fiber cable, and more particularly to inserting an optical fiber cable by a flow of a fluid such as gas formed in the conduit. The present invention relates to a conduit for laying an optical fiber cable.

<Technical Background of the Invention> In recent years, with the development of optical communication technology using optical fibers, the usage forms have been diversified, and there has been an idea to further rationalize the laying of optical fiber lines. For example, as one of them, a thin pipe-like duct or a cable pipe in which thin pipes are assembled is laid in advance in a section that is not needed now but is expected to be needed in the future, and a line is required at a later date. The idea is to insert an optical fiber cable into the cable pipe when it becomes.

The merit of this idea is that the optical fiber line can be installed for the first time at a necessary time, avoiding the prior installation of the optical fiber line which is not used for the time being, suppressing the initial investment.
This idea is based on the viewpoint of securing land, construction cost, space, etc.
It is effective for the construction method when constructing an optical communication network using existing wiring or wiring network such as water supply and sewerage.

On the other hand, as a method for inserting an optical fiber cable into a conduit, there is "a method and apparatus for laying an optical fiber cable" proposed in Japanese Patent Laid-Open No. 59-104607.

The method disclosed in Japanese Patent Laid-Open No. 59-104607 discloses a method such as a gas medium flowing at a speed higher than the traveling speed of the optical fiber cable in the traveling direction of the optical fiber cable to be inserted into the conduit. The flow of fluid is generated and the optical fiber cable is inserted by the pressure.

<Problems to be Solved by the Invention> However, since the method proposed in the above-mentioned Japanese Patent Laid-Open No. 59-104607 utilizes the flow of fluid, the layable distance is within the pipeline. It depends on the weight and surface shape of the optical fiber cable to be inserted into the pipe, and is determined by the pressure of the fluid flowing in the pipe at that time and the inner diameter of the pipe.

Further, in order to extend the laying distance, it is necessary to reduce the contact resistance of the conduit to the optical fiber cable, and it is desirable that the conduit be close to a bent portion or a straight state without twisting.

It is easy to achieve this condition with a single conduit, but with an assembly made up of multiple conduits, bending in the untwisted state may result in residual strain in the conduit. However, adverse effects such as flattening of the pipeline occur.

(C) It is also conceivable to take measures such as winding around a drum with a large diameter when manufacturing pipelines or laying pipelines in an attempt to reduce residual strain without twisting. Is not always an efficient method.

This invention was made in order to eliminate the above problems in the optical fiber cable laying conduit, and the contact resistance of the inner peripheral wall surface of the optical fiber cable is small,
Also, due to bending and twisting, residual strain may occur in the pipe,
It is an object of the present invention to provide a conduit for laying an optical fiber cable that allows an optical fiber cable to be easily inserted without flattening.

<Means for Solving Problems> The optical fiber cable laying conduit of the present invention for achieving the above object is formed by a tubular body having two layers of inner and outer layers, and Young's modulus of the outer layer is It is characterized in that it is formed to have a Young's modulus smaller than that of the layer.

<Operation> As described above, since the tubular body is configured to have an inner-outer two-layer structure, even if a plurality of conduits are assembled without twisting, the outer layer with a low Young's modulus acts as a buffer layer. , The deviation due to the extension of the pipes is eliminated. As a result, even if the pipe is wound on a drum at the time of manufacturing and laying the pipe, the residual strain is small and the pipe is not flattened.

Therefore, the conduit can be laid in a straight line, and the contact resistance of the inner surface of the conduit to the optical fiber cable can be reduced.

<Example> Next, a typical example of the present invention will be described with reference to a comparative example.

FIG. 1 is a perspective view of an essential part showing the construction of an embodiment of the optical fiber cable laying conduit of the present invention. The optical fiber cable of the embodiment has a cylindrical jacket 2 in which the tubular body is a bundle of 7 pipe lines 1 each having a double-layered structure including an inner layer 1a and an outer layer 1b, and the side faces of the respective pipe lines 1 are closely packed. It is configured to be inserted inside.

In this embodiment, the inner layer 1a of the conduit 1 is made of polyethylene,
The outer layer is made of polyurethane resin or vinyl chloride resin. Vinyl chloride resin is flame-retardant and is especially effective when laying pipes indoors. It is also possible to use a metal pipe in the inner layer of the pipeline 1, and in this case, the outer layer 1b of the pipeline.
It is effective because it uses plastic.

The ratio of the wall thickness of the inner layer to the outer layer of the pipeline should be selected within a range in which the shape of the inner surface of the pipeline does not change when bent.

In order to compare the performance of the optical fiber cable laying conduit according to the present invention, a polyethylene pipe with an inner diameter of 6 mm and an outer diameter of 8 mm was used, and the inner layer was 0.5 mm thick with polyethylene and the outer layer was 0.5 mm thick with vinyl chloride resin. For comparison, seven cylindrical pipes each having the structure of the present invention were assembled without twisting as shown in FIG. In a comparative experiment, a pipe having a diameter of 1 m and a pipe line of 20 m are wound around and unwound several times to confirm the flatness and arrangement of cylindrical pipes. Body diameter 1m
When it is wound on, the outer cylinder pipe is stretched by 0.8% and the outer cylindrical pipe is stretched by about 2% in the structure in which seven pipes are gathered. As a result, in the case of a cylindrical pipe made of polyethylene, there were problems such as flattening at the central cylindrical pipe by protruding and dropping at the terminal part by repeating winding and feeding several times, whereas
In the structure of the present invention, the flatness of the pipe, the disorder of the arrangement, and the abnormality of the terminal portion were not recognized. This is because when the pipe is bent, the low Young's modulus layer, which is the outer layer of the cylindrical pipe, absorbs the difference in elongation of the adjacent cylindrical pipes and does not directly affect the inner layer. Has been shown to be effective enough.

<Effect of Device> As is apparent from the above description, in the optical fiber cable laying conduit of the present invention, the tubular body of the conduit through which the optical fiber cable is inserted has an inner and outer two-layer structure, and By making the Young's modulus smaller than that of the inner one, the outer layer acts as a buffer layer when bent, absorbs strain and reduces the influence on the inner layer, and the inside of the conduit through which the optical fiber cable is inserted Is not damaged by flattening. Therefore, it becomes possible to collect a plurality of conduits without twisting, the contact resistance between the conduits and the optical fiber cable can be reduced, and the laying distance of the optical fiber cable can be extended. Further, since the flexibility is improved, it has an advantage that it can be applied to a portion having many curved portions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the structure of an optical fiber cable laying conduit according to the present invention, and FIG. 2 is compared with the performance of the optical fiber cable laying conduit according to the present invention. FIG. 7 is a perspective view of a main part showing a structure of a conventional conduit for laying an optical fiber cable for the purpose of FIG. In the drawing, 1 ... Pipeline, 1a ... Pipeline inner layer, 1b ... Pipeline outer layer, 2 ... Cylindrical jacket.

Claims (1)

[Scope of utility model registration request] 1. A pipe line comprising a plurality of tubular bodies having an inner and outer two-layer structure, which are assembled and used, wherein the Young's modulus of the outer layer is smaller than the Young's modulus of the inner layer. A conduit for laying an optical fiber cable.