JPS61141411A - Compound optical fiber cable - Google Patents

Abstract

PURPOSE:To assure high flexibility by inserting tension members having high tensile strength into a cable and forming plural protective layers around optical fibers. CONSTITUTION:The optical fiber is a quartz optical fiber and is formed with a clad 12 and further a protective layer 20 consisting of nylon, etc. around a core 11. An optical fiber cord 10 including up to such protective layer is formed. The direct protective layer 13 has a function as a tension member and increases the tensile strength of each optical fiber cord 10 to prevent the cutting, etc. of the optical fiber cord inn sich a case when bending stress is exerted over the entire part of the cable. One optical fiber cable including a sheath 14 is formed around the direct protective layer 13 and further an external sheath 19 is formed to the outermost circumferential part so that the entire part is formed as one compound cable.

Description

[Detailed Description of the Invention] Field of Application of Industrial Field> The present invention can be suitably implemented in devices where it is difficult to secure a light transmission path with a fixed cable, such as a flame monitoring device using optical fibers. Regarding optical fiber cables.

BACKGROUND OF THE INVENTION Accurately detecting the combustion state of various types of combustion equipment, including large-scale boilers in business establishments, is extremely important from the economic and safety standpoints. Taking a large boiler for a power plant as an example, an increase in the number of burners installed due to the increase in boiler capacity, an increase in the number of burner ignitions and extinguishments due to medium load operation of large boilers, and an increase in nitrogen oxide (NOx)
), as well as changes in combustion behavior due to diversification of fuels, it is desired to further improve the reliability of burner flame detection.

Here, the flame detector uses the heat of the flame.

Flames are detected by detecting either light or electrical properties, but the method of detecting flames by detecting light not only detects the presence or absence of flames, but also detects the light emitted by flames. Since it is basically possible to analyze the properties of a flame by analyzing the frequency, etc., it is possible to obtain a lot of information about the flame formation.

In conventional optical flame detectors, a heat-resistant mirror or lens is placed at the tip of a cylindrical head, and the light detected by these mirrors is guided to the outside of the boiler through the head. The presence or absence of flame was detected. However, with this method, the field of view is limited to one depending on the angle at which the mirror or lens is attached, and although it is possible to detect a part of the flame, it is not possible to detect the brightness distribution of the entire flame, and the properties of the flame cannot be detected. It was virtually impossible to detect. In addition, the narrow field of view makes it difficult to distinguish between the light from other flames and the light from the burner flame that is to be detected, which often causes detection errors. Furthermore, due to low NOx combustion, a considerable amount of unburned substances are suspended near the flame formation area, reducing the permeability of the entire furnace, further reducing the reliability of conventional equipment with a single field of view. The reality is that it is.

For this reason, the inventors have separately proposed a multi-view flame monitoring device using seven optical fibers as shown in FIG. In the figure, reference numeral 1 denotes an outer cylinder constituting the main body of the apparatus, and 2 denotes a lighting head attached via a support member 3 near the tip of the outer cylinder 1. Three grooves are formed at the tip of the lighting head 2 at different angles toward the tip opening 3a of the support member, and three optical fibers 4 (4a, 4b, 4c) are formed in each groove. ) are stored and arranged, and each one is R5a, 5
They are arranged to have a constant field of view centered on b, 5 and c.

Next, reference numeral 6 denotes an inner cylinder disposed within the outer cylinder 1 with a certain space therebetween, and numeral 7 denotes a connector disposed within the inner cylinder 6.
The optical fiber 4 passes through this connector 7 to the window ``X'' attached to the base of the outer tube 1.The cooling air A entering the inner tube 6 Some of it is ejected from around the lighting head 2, and the other part is ejected from around the protective member that houses the lighting head,
Cools the main body and the optical fiber housed inside.

An optical fiber cable is connected to the flame monitoring device with the above configuration, and the detected light is transmitted to a separate detection device via the cable, and the light is converted into an electrical signal here to determine the presence or absence of a flame. Detection, analysis of flame properties, etc. are performed. When the need for flame monitoring arises, the fire monitoring device itself should be moved through a wind box so that its tip is close to the flame, and then pulled out to the outside where monitoring is not required, so that the device is not exposed to high temperatures for long periods of time. This prevents the For this reason, the optical fiber cable connected to the monitoring device cannot be fixedly installed at a fixed location, unlike when used for optical communications. For this reason, high flexibility is required to accommodate the insertion and removal of the device, and since there are many impacts from the outside, a structure that can sufficiently protect the optical fiber from such impact is required.

OBJECTS OF THE INVENTION The present invention was constructed in view of the above-mentioned needs, and an object of the present invention is to provide an optical fiber cable that has high flexibility and can sufficiently protect optical fibers.

Summary of the Invention In short, the present invention includes a high tensile tension member placed inside the table to obtain a strong tensile force, and a plurality of protective layers formed around the optical fiber to withstand impact.
Moreover, it is constructed to ensure flexibility.

<Example> An example of the present invention will be described below with reference to FIG. Reference numeral 10 in the figure is an optical fiber cord corresponding to three optical fibers arranged in the flame monitoring device. The optical fiber is a silica-based optical fiber (the softening degree of quartz glass is approximately 13006C)
), reference numeral 11 is a core, 12 is a cladding formed around the core, and a protective layer 20 of nylon or the like is further formed around the cladding, and the optical fiber cord 10 is formed including this protective layer. do. A direct protection layer 13 is formed around the optical fiber cord, and is in close contact with the optical fiber cord 10 to directly protect the optical fiber cord. This direct protective layer also functions as a tension member, increasing the tensile force of each optical fiber cord 10 when bending stress is applied to the entire cable, thereby preventing the optical fiber cord from being cut. . Suitable materials for the direct protective layer include high tensile cablastic fibers that are flexible and have high tensile strength. 14 is a sheath formed directly around the protective layer 13, and including this sheath forms one optical fiber cable. As this sheath, vinyl chloride resin (hereinafter abbreviated as "PVCJ") is suitable. In the case of the figure, three optical fiber cables are arranged corresponding to the number of optical fibers on the apparatus main body side. Reference numeral 15 is a cable-shaped intervening member having an outer diameter approximately equal to that of these optical fiber cables, and a tension member 16 is arranged at the center of the four cables including this intervening member 15.

This tension member is for increasing the tensile force of the entire composite cable, and is preferably a wire rope or the like.

Reference numeral 17 denotes a filler filled between the optical fiber cable and the intervening member, and further, in order to form these into one piece, a plastic tape is used to press and wrap 18.
Furthermore, an outer sheath 19 is formed at the outermost periphery to form the entire cable into one composite cable. Although the present invention has been described above using an example of use in a flame monitoring device, the present invention is not limited to this, and can be used in any field where high strength and sufficient flexibility are required for cables.

Effects> Since the present invention is constructed as described above, each optical fiber cord is sufficiently protected from external impact, exhibits high tensile strength, and exhibits good flexibility.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a composite optical fiber cable, and FIG. 2 is a sectional view of a flame monitoring device. 1
10... mark Optical fiber cord 11... core 12... clad 13... direct protective layer 14... sheath 15... intervening Member 16...Tension member 19...External sheath

Claims (1)

[Claims] 1. An optical fiber cable is constructed by forming a protective layer directly on the optical fiber cord and forming a sheath around the direct protective layer, and comprising a plurality of optical fiber cables and a tension member. What is claimed is: 1. A composite optical fiber cable comprising: a composite optical fiber cable which is integrally held together and an outer sheath formed into an integrated cable. 2. The number of optical fiber cables is three, and in addition to these optical fiber cables, an intervening member that is a cable-like object having an outer diameter approximately equal to that of the optical fiber cable is arranged, and a tension member is placed around the optical fiber cable and the intervening member. 2. A composite optical fiber cable according to claim 1, wherein said composite optical fiber cable is provided with: