JPH073371Y2 - High-strength optical fiber cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the structure of an optical fiber cable, and more particularly to the structure of a high-strength optical fiber cable that is directly buried in the ground and used.

[Conventional technology]

Conventionally, as an example of an optical cable directly buried in the ground for use, iron wires or steel wires are arranged around the inner sheath 22 covering the optical fiber cable core 21 whose sectional structure is shown in FIG. Then, there is an iron wire illuminating optical cable having a structure in which the glazing iron wire 23 and the outer sheath 24 made of plastic are laminated and coated.

As another example, a corrugated steel pipe mounted optical cable in which a corrugated steel pipe 33 and an outer sheath 34 made of plastic are laminated and coated on the outer circumference of an inner sheath 32 which covers the optical fiber cable core 31 and whose sectional structure is shown in FIG. There is.

The above-mentioned conventional optical cables are widely used for power cables, communication cables, optical fiber cables and the like.

[Problems to be solved by the invention]

If a metal insulation structure such as a conventional iron wire insulation cable or corrugated steel pipe insulation cable is applied to an optical fiber cable as it is, the overlap will be significantly increased, and the length of a single cable manufactured will increase from the manufacturing and construction aspects. Due to restrictions and shortening, and inevitably becoming a cable using metal, the features of the optical fiber cable are the lightweight, long length, and non-metallic optical fiber cable configuration that can be manufactured as needed. However, there is a problem in that the features of the optical fiber cable cannot be fully exerted or the features are impaired. There is also a problem that the price becomes expensive.

It is an object of the present invention to solve the conventional problems and to provide an inexpensive and practical high-strength optical fiber cable which does not impair the characteristics of the optical fiber cable and has the performance applicable to direct burying. It is a thing.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides an optical fiber cable in which a plastic inner sheath and a plastic outer sheath are provided on the outer periphery of an optical fiber cable core.
The outer sheath has a plurality of protrusions forming an inclination angle with respect to the outer surface of the inner sheath, and the inner sheath and the outer sheath have a structure in which the optical fiber cable core is concentrically covered. I am trying.

Further, the vicinity of the tips of the multiple projections of the outer sheath is in contact with the outer surface of the inner sheath, and the vicinity of the tips of the multiple projections of the outer sheath has a gap with respect to the outer surface of the inner sheath. It is effective to have a structure having.

[Action]

In an optical fiber cable having a structure in which a plurality of slanted projections are provided on the inner surface of the outer sheath of the present invention, excessive pressure is applied to the cable body when it is directly buried in the ground and used, When a large impact force is instantaneously applied, an external force is first applied to the outer sheath. When this external force is a large external force that deforms the outer sheath, the outer sheath begins to flatten, but at this time, the tip of the protrusion provided on the inner surface of the outer sheath must have a structure inclined with respect to the outer surface of the inner sheath. As a result, when the outer sheath is flat, the inclination angle of the protrusions also changes so as to reduce the external force applied to the inner sheath, so the external force applied to the outer sheath directly affects the inner sheath and thus the optical fiber cable core. It has no additional force and has a sufficient protection function against external pressure.

Even if the protrusion tip of the inner surface of the outer sheath is in contact with the outer surface of the inner sheath, or if there is a slight gap between the tip of the protrusion of the inner surface of the outer sheath and the outer surface of the inner sheath, there is no problem in operation. The state with the voids is more suitable for further enhancing the protective function against external force.

In the present invention, it is essential that the optical fiber cable core and the inner sheath and the outer sheath have a substantially concentric structure, especially when there is a gap between the projection tip of the inner surface of the outer sheath and the outer surface of the inner sheath. If the gap is too large, when the optical fiber cable of the product is wound on the drum, there is a difference in length between the outer sheath and the inner sheath with the optical fiber cable core covered, and the optical fiber cable is extended from the drum. When doing so, a large difference in length may occur between the outer sheath and the inner sheath and the optical fiber cable core. Embodiments will be described below with reference to the drawings.

〔Example〕

FIG. 1 is a view showing the cross-sectional structure of an embodiment of the high-strength optical fiber cable of the present invention, in which 1 is an optical fiber cable core,
Reference numeral 2 denotes an inner sheath, and 3 denotes an outer sheath provided with a plurality of protrusions 4 forming an inclination angle with respect to the outer surface of the inner sheath.

The structure of the high-strength optical fiber cable of the present invention is different from the conventional metal-insulated optical cable having a metal layer between the inner sheath 2 and the outer sheath 3 in order to withstand pressure and impact force from the outside of the cable body. The outer sheath 3 is directly applied to the outer circumference of the inner sheath 2 except for the metal layer. In the structure of the present invention, a large external pressure applied under the underground installation condition is provided by providing a plurality of protrusions on the inner surface of the outer sheath 3 which are inclined at an appropriate angle with respect to the outer surface of the inner sheath 2. External force is not directly transmitted from the inner sheath 2 to the inner side against the impact force. Especially, the optical fiber cable is vulnerable to a large external pressure and impact force, and may be broken when directly receiving an external force, but the performance of the optical fiber cable for underground embedding is improved by the external sheath structure of the present invention. It can be maintained and is very effective.

The inner sheath 2 and the outer sheath 3 are plastics made of non-metallic material, and by making all the constituent materials of the optical fiber cable core 1 non-metallic material, a non-metallic optical fiber cable as a whole can be constructed.

An optical fiber cable containing a metal as a conventional constituent material is apt to corrode the metal member when it is laid and used for a long time in the ground and may deteriorate the performance of the optical fiber cable. The non-metallic optical fiber cable of the present invention does not have such a fear. Moreover, even if it is installed close to a high-voltage power cable, it is not affected by electrical induction, and a safe and practical optical fiber cable can be realized.

Next, a specific example of the embodiment of the present invention shown in FIG. 1 will be described. As the optical fiber cable core 1, for example, an optical fiber core wire is gathered further on the outer circumference of a steel wire or FRP tensile strength body, and a plastic yarn is applied to the outer circumference thereof as a buffer layer. The optical fiber cable core 1 which was wound by pressing was used.

The inner sheath 2 was formed by concentrically covering the outer periphery of the presser winding with polyethylene, vinyl, aluminum laminated polyethylene, etc., in a predetermined thickness.

The outer sheath 3 is formed by covering the outer circumference of the inner sheath 2 with plastic. As the plastic material to be applied, a hard material is preferable in order to enhance the protection function against external force, and for example, polyethylene, especially high-density polyethylene, ABS resin semi-hard vinyl, etc. were used.

The outer sheath 3 is also effective as a two-layer structure in which polyethylene is used on the inner surface side and polyamide resin is used on the outer surface side.

The inner surface of the outer sheath 3 is provided with a plurality of projections 4 inclined with respect to the outer surface of the inner sheath 2. The number and size of the projections 4 are set according to the outer diameter of the inner sheath 2.

The height of the protrusion 4 is preferably about 1.5 to 3 mm, the inclination angle of the inner sheath 2 with respect to the outer surface is preferably about 15 to 50 degrees, and the number of threads is preferably large.

The projection 4 may be inclined with respect to the outer surface of the inner sheath 2, and its shape is not particularly limited to the shape illustrated in the embodiment of FIG.

The outer sheath 3 can be easily manufactured in one step by continuously using a plastic molding machine to obtain a desired long length. The outer sheath 3 is shaped and dimensioned by processing a molding die into a desired shape.

When a space is provided between the outer surface of the inner sheath 2 and the vicinity of the tip of the plurality of protrusions 4 of the outer sheath 3, the molding can be easily performed by appropriately setting the manufacturing conditions at the time of molding. The gap to be formed is preferably set to about 1 mm or less so that the inner sheath 2 and the outer sheath 3 are substantially concentric and there is no difference in length between the inner sheath 2 and the outer sheath 3.

〔The invention's effect〕

As described above, the high-strength optical fiber cable of the present invention does not use metal insulators, but has a structure having a plurality of protrusions inclined to the outer surface of the inner sheath on the inner surface of the outer sheath that directly covers the inner sheath. Therefore, by adopting the optical fiber cable according to the present invention,
It does not impair the features of the optical fiber cable such as long length and non-metallic shape, and it does not impair the performance of the optical fiber cable against external pressure or impact force, so it can be used directly in the ground. It can be applied for burial and can supply optical fiber cables at low cost, and at the time of installation work,
The labor is reduced, and the effect is rational and economical in the construction of optical fiber transmission lines such as underground and buried.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural view of a high-strength optical fiber cable embodiment of the present invention, FIG. 2 is a cross-sectional structural view of a conventional iron wire-insulated optical cable, and FIG. 3 is a cross-sectional structural view of a conventional corrugated steel pipe-insulated optical cable. is there. 1,21,31 …… Optical fiber cable core, 2,22,32 …… Inner sheath, 3,24,34 …… Outer sheath, 4 …… Protrusion, 23 ……
Iron wire for girth, 33 ... Corrugated steel pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroji Ogata Inventor Hiroji Ogata Shibata-machi, Shibata-gun, Miyagi Prefecture 1-4 Yamada, Funaoka, Kita Nippon Electric Cable Co., Ltd. Funaoka Plant (72) Akira Kurosawa, Shibata, Shibata-gun, Miyagi Prefecture Funaoka 1-4 Yamada, Kita Nippon Electric Cable Co., Ltd., Funaoka Plant (56) Bibliography Sho 63-192613 (JP, U)

Claims (3)

[Scope of utility model registration request] 1. An optical fiber cable in which a plastic inner sheath and a plastic outer sheet are provided on the outer periphery of an optical fiber cable core, wherein the outer sheath (3) has an inclination angle with respect to the outer surface of the inner sheath (2). A plurality of protrusions (4) forming the inner sheath (2) and the outer sheath (3) are concentrically covered with the optical fiber cable core (1). A high-strength optical fiber cable. 2. A high-strength optical fiber cable according to claim 1, wherein the outer sheath has a plurality of protrusions in the vicinity of the tips thereof in contact with the outer surface of the inner sheath. 3. The high-strength optical fiber cable according to claim 1, wherein a plurality of protrusions of the outer sheath have a gap near the tip of the outer surface of the inner sheath.