JPH07225173A - Housing structure of liquid-leak detection sensor using optical fiber - Google Patents

Abstract

PURPOSE:To provide a housing structure, of a sensor, in which the connection excess length of an optical fiber can be treated easily in the oil-leak detection apparatus of an OF cable using an OTDR. CONSTITUTION:In the housing structure of a liquid-leak detection sensor, a sensor 1 is arranged on a covering 2, composed of lead, for an OF cable, and a corrosion-protective layer 3 is executed onto it. In the housing structure, a lead fiber 8 for the sensor 1 is extracted so as to be passed through the corrosion-protective layer 3. Then, its extraction direction is set on the downstream side when an armor wire is wound. Thereby, a fiber, for transmission, which is connected to the lead fiber 8 is wound together with the armor wire so that an excess length can be treated easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage structure for a leak detection sensor for detecting oil leaks in OF cable joints and the like.

[0002]

2. Description of the Related Art Conventionally, as an oil leakage detection sensor using an optical fiber, there is one disclosed in Japanese Patent Laid-Open No. 3-197843. This utilizes OTDR, in which the swelling material that expands by absorbing the leaked oil bends the optical fiber, and the leaked oil is detected from the accompanying increase in transmission loss. However, there is no actual example in which such a sensor is housed in an OF cable, and it is applied to an OF cable by using an element whose resistance value changes due to oil leakage (actual flat cable 3-
(See Japanese Patent No. 115833)) and so on.

If the sensor as described above is housed in an OF cable, it may be considered to be housed between the anticorrosion layer and the metal layer. In that case, the signal from the sensor was connected to the lead fiber (or directly to the sensor)
The lead fiber and the transmission fiber are usually arranged under the anticorrosion layer, though they are sent to the terminal device through the transmission fiber.

[0004]

However, for example, when the cable is damaged and an attempt is made to repair the part, it is necessary to cut the damaged part and add a replacement cable to the damaged part. Therefore, it is necessary to connect the optical fiber. Occurs. At this time, if the optical fiber is stored under the anticorrosion layer, there is a problem that the storage of the extra length caused by the connection becomes very complicated.

[0005]

The present invention has been made to solve the above-mentioned problems, and a sensor is arranged on a metal sheath in a joint portion or the like of an OF cable, and an anticorrosion layer is provided thereon. The liquid leakage detection sensor is housed in a structure, wherein the lead fiber of the sensor penetrates the anticorrosion layer and is drawn out, and the drawing direction is the downstream side when the armoring wire is wound.

Here, when a pigtail fiber is provided in the sensor or two lead fibers are provided so that liquid leakage can be detected from both sides of the sensor, the pigtail fiber and the second lead fiber also penetrate the anticorrosion layer. It is preferable to pull out in the same direction as the first lead fiber.

[0007]

EXAMPLES Examples of the present invention will be described below. FIG. 1 shows an embodiment in which an oil leak sensor is embedded in a joint portion of an OF cable. As shown in the figure, the sensor 1 is arranged on a lead sheath (metal sheath) 2 of the OF cable, on which polyethylene is anticorrosive. Layer 3 has been applied.

Here, as the sensor 1, for example, the one shown in FIG. 3 proposed by the present inventor (1993 Patent Application No. 60912) can be applied. This is a sensor in which an optical fiber 6 is arranged between a swelling member 4 that absorbs leaked oil and swells and a cylindrical stress applying member 5, and the swelling member 4 is expanded by leaking oil introduced from an opening 7. Then, the optical fiber 6 is pressed against the stress-applying member 5 to bend it, and a change in the light intensity due to an increase in transmission loss is detected by the OTDR.

Examples of the swelling member 4 include ethylene propylene rubber and the like, and if it is made of a vinyl alcohol acrylate copolymer or the like that absorbs water and expands, the infiltration of water into the anticorrosion layer can be detected. Further, the extra length of the optical fiber is wound around the extra length processing section b with a margin to prevent the optical fiber from being subjected to abnormal bending or tension. Note that FIG. 3 shows the sensor 1 viewed from the outer circumference of the cable, and the sensor box 12 corresponds to the sensor 1. Of course, the sensor structure is not limited to such a structure, but a known structure that can be used for OTDR (the technique described in the above-mentioned JP-A-3-197843).
Etc. can be widely applied.

A lead fiber 8 is connected to one end of such a sensor 1 (FIG. 1). In this example, the pigtail fiber 9 is also provided on the other side of the sensor in addition to the lead fiber. This is to prevent normal measurement from being impossible due to the influence of the reflection of light at the end face of the optical fiber when liquid leakage is detected by OTDR. Both fibers 8 and 9 are wound around the lead cover 2 several times, penetrate the anticorrosion layer 3, and are drawn to the outside.

Here, the direction of pulling out both fibers was set to the downstream side when the steel sheath wire 10 was applied on the anticorrosion layer as shown in FIG. The lead fiber 8 sends a signal to a terminal (not shown)
The pigtail fiber 9 is connected to the transmission fiber 11 for sending to the optical fiber, and the pigtail fiber 9 is cut with a length that can sufficiently remove the influence of the reflection of light at the end of the optical fiber, and the end treatment is performed if necessary. Then, by making the pull-out direction of both of these fibers the downstream side when applying the armoring wire, it is possible to wind these fibers together with the armoring wire 10 in the same direction, and to process the optical fiber when manufacturing the sensor built-in cable, or Makes it extremely easy to store the extra connection length when repairing the cable.

In the above example, one lead fiber is used so that measurement can be performed from one side of the sensor. However, in order to perform measurement from both sides of the sensor, a lead fiber is provided instead of the pigtail fiber, and a total of 2 lead fibers are provided. A book lead fiber configuration may be used. With this configuration, even if one optical fiber breaks, the other one can perform measurement.
Also in this case, like the pigtail fiber, it can be wound on the anticorrosion layer together with the armoring wire by pulling it out in the same direction as the first lead fiber.

[0013]

As described above, in the structure of the present invention, the lead fiber is drawn out of the anticorrosion layer, and the transmission fiber connected to the lead fiber can be wound around the anticorrosion layer together with the armor wire. The degree of freedom of the fiber is greater than that of the conventional one with the optical fiber arranged below, and it is easy to store the extra length when repairing a damaged cable.
Further, not only at the time of repair, but also when manufacturing the cable housing the sensor, the optical fiber connected to the sensor can be efficiently manufactured by winding the optical fiber together with the armoring wire. Therefore, it can be expected to be effectively used for oil leak detection of submarine cables.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a storage structure of the present invention.

FIG. 2 is an explanatory view showing a process of an optical fiber drawn out from the structure of the present invention.

FIG. 3 is a schematic view of a leak detection sensor used in the present invention.

[Explanation of symbols]

 1 sensor 2 lead coating 3 anticorrosion layer 4 swelling member 5 stress applying member 6 optical fiber 7 opening 8 lead fiber 9 pigtail fiber 10 exterior wire 11 transmission fiber 12 sensor box 13 case a stress applying part b extra length processing part

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshiaki Hara, 3-3-22 Nakanoshima, Kita-ku, Osaka, Kansai Electric Power Co., Inc. (72) Kazuo Yokota, 3-22-3 Nakanoshima, Kita-ku, Osaka Kansai Electric Power Co., Ltd. (72) Inventor Yoshikazu Murata 1-3-1 Shimaya, Konohana-ku, Osaka City Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Hideaki Nijima 1-1-1, Shimaya, Konohana-ku, Osaka City No. 3 Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Yuji Naka, 1-3-1 Shimaya, Konohana-ku, Osaka City Sumitomo Electric Industries Co., Ltd. (72) Inventor Aki Otsuki Shimano, Konohana-ku, Osaka Sumitomo Electric Industries Co., Ltd. Osaka Works, 1-33 (72) Inventor Hisao Koga 1-3-3 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries, Ltd. Osaka Inside the factory

Claims (2)

[Claims] 1. A storage structure for a leak detection sensor, in which a sensor is arranged on a metal sheath in a joint portion or the like of an OF cable, and an anticorrosion layer is applied on the sensor, and the lead fiber of the sensor has the anticorrosion layer. A housing structure for an optical fiber leak detection sensor, characterized in that it is penetrated and drawn out, and that this drawing direction is the downstream side when the armoring wire is wound. 2. The optical fiber leakage detection sensor according to claim 1, wherein the sensor is provided with a pigtail fiber, and the pigtail fiber also extends through the anticorrosion layer in the same direction as the lead fiber. Construction.