JPH1020165A - Optical cable - Google Patents

Abstract

(57) [Problem] To provide an optical cable having a function of optically detecting temperature. A single-core optical fiber core and a first filler, or a single-core optical fiber core and a second filler, are in contact with each of a plurality of slot grooves in an optical cable. It is assumed that the grouped spacer type optical cable is housed. The slot groove filled with the second filler 7 having high temperature-dependent consistency becomes a slot groove for temperature detection, and the single-core optical fiber core 6 accommodated in the slot groove is used for temperature detection. Different types of 1st and 1st in the same optical cable
An optical fiber core for temperature detection is provided in the same cable by a structure in which the second fillings 5 and 7 are filled and the fillings 5 and 7 are separated so as not to mix.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable for detecting temperature. An optical fiber core for temperature detection and an optical fiber core for communication can be housed in the same optical cable, and the optical cable itself in a place where temperature changes rapidly, such as an optical cable laid around the liquid nitrogen tank. It can be used for temperature detection.

[0002]

2. Description of the Related Art Conventionally, as a temperature sensor, for example, a waterproof / moisture-proof temperature sensor made of a magnetic material having a temperature-dependent magnetic characteristic as disclosed in Japanese Patent Application Laid-Open No. 52-46878, There is one in which a thermistor element is housed in a heat-resistant metal tube with a cap as described in Japanese Unexamined Patent Publication No. 4-282427. Conventional devices of this type
An electrical device is required for transmitting detection information between the device under test and the measuring device. In addition, due to the configuration of the device, it is very difficult to attach it to an optical cable.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical cable which does not require an electrical device and has a function of optically detecting temperature.

[0004]

According to a first aspect of the present invention, in the optical cable according to the first aspect of the present invention, the optical cable has an optical fiber housing portion filled with a filler so as to contact an optical fiber core. The filler is characterized in that it has a temperature-dependent consistency that increases the transmission loss of the optical fiber as the temperature decreases.

According to a second aspect of the present invention, in the optical cable, the optical cable has a plurality of optical fiber housings, and a part of the optical fiber housings is filled with a filler so as to be in contact with the optical fiber core. The filler has a temperature-dependent consistency that increases the transmission loss of the optical fiber core according to a temperature decrease, and the optical fiber core is contained in at least some other optical fiber housings. It is characterized in that it is housed so that transmission loss does not increase with a decrease in temperature.

According to a third aspect of the present invention, in the optical cable according to the first or second aspect, the filler has a consistency of 200 or less at -40 ° C.

According to a fourth aspect of the present invention, in the optical cable according to any one of the first to third aspects, the optical fiber housing portion is groove-shaped or tubular. .

According to a fifth aspect of the present invention, in the optical cable according to any one of the first to fourth aspects, the optical fiber cores housed in the part of the optical fiber housings are coated with Young. The rate is 70 kg / mm ² or less.

[0009]

FIG. 1 is a sectional view of an optical cable according to a first embodiment of the present invention. In the figure, 1 is a jacket, 2 is a press winding, 3 is a slot rod, 4 is a tensile member, 5 is a first filling, 6 is a single-core optical fiber, and 7 is a second filling. In this embodiment, the single-core optical fiber core 6 and the first filler 5 or the single-core optical fiber core 6 and the second filler 7 contact each of the plurality of slot grooves in the optical cable. It is assumed that a grouped spacer type optical cable stored in a state is used.

[0010] Some of the slot grooves are filled with a second filler 7 having a property different from that of the first filler 5 of the other slot grooves and having a high temperature-dependent consistency. , And the single-core optical fiber core wire 6 housed therein becomes the optical fiber core wire for temperature detection. Therefore, the same optical cable is filled with different types of first and second fillers 5 and 7, and the single-core optical fiber core 6 and the first
The optical fiber core for temperature detection is separated by a structure in which the filler 5 or the single-core optical fiber core wire 6 and the second filler 7 are in contact with each other so as not to mix with each other. The wires are provided in the same cable.

The slot rod 3 has a tensile member 4 at the center, and has six U-shaped slot grooves around the periphery. The tensile strength member 4 is, for example, a steel stranded wire in which seven wires are twisted around one center. Each of the slot grooves accommodates at least one single-core optical fiber core wire 6 and is filled with fillers 5 and 7. A presser winding 2 is provided around the slot rod 3 to form an optical cable core. The top of the presser winding 2 is covered with a jacket 1. Since the single-core optical fiber 6 and the fillers 5 and 7 are prevented from coming out of the slot grooves, the first and second fillers 5 and 7 are isolated without being mixed.

Incidentally, there is a case where there is a slot groove not accommodating the single-core optical fiber core 6 due to being taken out in the middle of the optical cable. In some cases, the slot rod 3 has only one slot groove. In this case, only the slot groove for temperature detection is used.

FIG. 2 is a sectional view of a specific example of an optical fiber core used in the optical cable of the present invention. 11 is a silica glass fiber, 12 is a primary coating, 13 is a secondary coating, 14
Is a coated optical fiber, 15 is a tape coating, and 16 is a tape-shaped optical fiber core. As the optical fiber used in the optical cable of the present invention, a single-core optical fiber 6 as shown in FIG. 2A or a tape-shaped optical fiber 16 as shown in FIG. In FIG. 1, a single-core optical fiber core wire 6 is used.

As shown in FIG. 2A, a single-core optical fiber core wire 6 is made of a silica-based glass fiber containing silica glass as a main component and having a core portion and a cladding portion, and a single layer or a plurality of layers of ultraviolet rays. The coating with the cured resin, in the illustrated example, the primary coating 12 and the secondary coating 13 are applied. FIG.
As shown in FIG. 2B, the tape-shaped optical fiber is composed of a plurality of coated optical fibers 14, such as the single-core optical fiber shown in FIG. The tape coating 15 of a single layer or a plurality of layers is applied.

Returning to FIG. 1, the components of the optical fiber cable will be described. As the second filler 7 filled in the slot for temperature detection, one having a large temperature dependency of the consistency is used, and the consistency becomes low in response to the temperature drop in the external environment, and the single-core optical fiber core contacting the same. No. 6 which greatly increases the transmission loss is used. It is important that the temperature dependency is large and the consistency is low. Therefore, this single-core optical fiber core 6 serves as a sensor for detecting temperature. On the other hand, as the first filling material 5, a material having a small temperature dependency of the consistency is used, and a single-core optical fiber core wire 6 contacting the first filling material 5 is used.
Is used as an optical fiber for communication without increasing transmission loss irrespective of a change in the external temperature.

Here, the consistency will be described. The consistency is defined by JIS K-2220 “grease” and is an index indicating the hardness of the filler. The smaller the value, the harder the material. This is a numerical value representing the depth of the specified cone penetrating into the sample within the specified time by 10 times the millimeter. Some packings have a consistency that is highly temperature dependent. As the temperature of the outside world decreases, the consistency decreases,
The flexibility of the filling material is reduced, and the difference in the amount of contraction between the single-core optical fiber core 6 and the slot rod 3 or the jacket 1, which is a cable constituent material, cannot be absorbed. 6, microvents occur and the loss increases.
By monitoring the increase in the loss of the single-core optical fiber 6, it is possible to detect a decrease in the external temperature.

Specific examples of the filler 5 include, for example, oil components such as silicone oil, polybutene oil, α-olefin oil and mineral oil, an oil separation inhibitor such as a styrene block copolymer, silica, bentonite, and the like. It is mainly composed of three kinds of thickener components made of clay or the like. In addition to these, there are also those to which, for example, an antioxidant, an ultraviolet stabilizer and the like are added.

The slot groove for temperature detection is provided with the holding roll 2 and the jacket 1 is provided thereon, so that the slot groove has a substantially constant cross-sectional area. The more flexible the coating of the optical fiber, the more easily the effect of the consistency of the second filling 7 is applied. Is smaller, the sensitivity of temperature detection is higher. Therefore, the Young's modulus of the single-core optical fiber core 6 for temperature detection may be the same as the Young's modulus of the conventional optical fiber core for communication, but is preferably smaller than this. Any of the single-core optical fibers 6 for temperature detection and communication may have a Young's modulus suitable for temperature detection.

FIG. 3 is a sectional view of an optical cable according to a second embodiment of the present invention. In the figure, the same parts as those in FIG. 21 is a tensile strength member. In this embodiment, the tape-like optical fiber 16 and the first filler 5 shown in FIG. 2 (B) or the tape-like optical fiber 16 shown in FIG. It is assumed that the tape slot type optical cable is stored in a state where the second filler 7 is in contact with the tape.
Compared to the grouped-spacer type optical cable shown in FIG. 1, a tape-shaped optical fiber core 16 is used instead of the single-core optical fiber core 6, and the cross-sectional shape of the slot groove is different. You are.

The central tensile member may be the tensile member shown in FIG. 1, but here, one tensile member 21 is used. As in FIG. 1, some of the slot grooves are filled with the second filler 7 to form temperature detecting slot grooves.
The tape-shaped optical fiber core 16 accommodated therein becomes an optical fiber core for temperature detection. Since only one optical fiber core for temperature detection may be used, a single core optical fiber core 6 may be housed in the slot groove for temperature detection instead of the tape-shaped optical fiber core fiber 16.

FIG. 4 is a sectional view of a third embodiment of the optical cable according to the present invention. In the figure, the same parts as those in FIG. 31 is a loose tube, 32 is a tensile member, and 33 is an intervening string. In this embodiment, each of a plurality of loose tubes 31 in an optical cable is filled with a single-core optical fiber 6 and a filler 5 or a single-core optical fiber 6 and a filler 5 shown in FIG. This is based on a loose tube type optical cable housed in a state where the object 7 is in contact with the loose tube type optical cable. As in FIG. 1, a part of the loose tubes 31 is filled with the second filler 7 to form a loose tube for temperature detection, and the single-core optical fiber core wire 6 accommodated in the loose tube 31 is used for temperature detection. Optical fiber.

A tensile strength member 32 coated at the center,
Four loose tubes and two intervening cords 3
3 are twisted. Each of the loose tubes 31 accommodates at least one single-core optical fiber core wire 6 and is filled with the first filler 5 or the second filler 7. A presser winding 2 is provided around the loose tube 31 and the intervening cord 33, and the presser winding 2 is covered with a jacket 1. Since the single-core optical fiber core wire 6 and the first and second fillers 5 and 7 do not come out of the loose tube 31, the first and second fillers 5 and 7 are isolated without being mixed.

In some cases, there may be a loose tube 31 in which the single-core optical fiber core 6 is not housed, for example, by being taken out in the middle of an optical cable. Further, there is a case where the single loose tube 31 itself becomes an optical cable by itself or as it is or a sheath is provided. In this case,
Only a loose tube for temperature detection is required.

[0024]

EXAMPLE An evaluation test was carried out using the optical cable shown in FIG. As the single-core optical fiber 6, a single-mode fiber having a fiber diameter of 125 μm and having an outer diameter of 250 μm obtained by coating two layers of an ultraviolet curable resin as shown in FIG. 2A was used. The coating of the single-core optical fiber core wire 6 has a Young's modulus of 65 to 68 kg / mm ² . The Young's modulus of a conventional ordinary single-core optical fiber cable for communication is 70 to 90 kg / mm ^2, which is slightly smaller than this value. When the tape-like optical fiber core 16 shown in FIG. 3 is used for temperature detection instead of the single-core optical fiber core 6, the Young's modulus of the communication tape-like optical fiber core 16 is 80 to 110 kg /. mm ²
On the other hand, it is preferable to set it to 80 kg / mm ² or less. A slot rod 3 having six slot grooves of the same shape is arranged around the strength member 4, and the first or second filler 5, which is isolated so as not to mix with each other, is provided in the slot groove.
7 and the optical fiber 6 were accommodated. In this case, four grooves are used for communication, the single-core optical fiber core wire 6 is filled with a first filler having a small temperature dependency of consistency, and two slot grooves are used for temperature detection. A fiber having a structure in which the fiber core wire 6 and the second filler having a large temperature dependency of the consistency were filled, and the respective fillers were not mixed was produced.

FIG. 5 is an explanatory diagram showing the composition and physical properties of the filler. FIG. 6 is a diagram showing the temperature dependence of the consistency of the fillings A to C and K. Although the diagram of the temperature dependence of the packings D to J is omitted, all the packings A to K are shown in FIG.
Is shown as a function of temperature. In the figure, A to K represent types of the packing. A to C are packing materials having a high temperature dependency of the consistency, and D to K are packing compositions having a low temperature dependency. The transmission loss increase at −40 ° C. is + 25 ° C.
It is the average loss increase of the optical fiber based on the transmission loss in the above.

As the first filling material 5 to be filled in the slot groove for communication, a filling material having a small temperature dependence of consistency such as K shown in FIGS. 5 and 6 was used. In the single-core optical fiber core wire 6 accommodated in the communication slot groove so as to be in contact with the first filling material 5, the loss does not change regardless of a change in the external temperature. As the second filler 7 filling the slot groove for temperature detection, a filler having a large temperature dependency of the consistency as shown in A of FIGS. 5 and 6 was used. In the optical fiber 6 housed in the temperature detecting slot groove so as to be in contact with the second filler 7, the loss changes due to a change in external temperature. When the loss of each core of the optical cable was measured in an environment of -20 ° C to + 60 ° C, the loss of the optical fiber in the slot groove filled with the K filler was hardly changed. The loss clearly increased in the optical fiber of the slot groove filled with the filler. The transmission loss increase (−d at −40 ° C. shown in the explanatory diagram of FIG. 5)
(B / km) is a value when an evaluation test is performed by inserting a single-core optical fiber core wire 6 for temperature detection into each of the fillers.

As shown in FIG. 5, the filler can be produced by selecting an oil component and a thickener component and mixing them at an appropriate mixing ratio. Can be adjusted. Since the packing for temperature detection has a consistency of −200 ° C. or less at −40 ° C., the transmission loss greatly increases as the temperature decreases from room temperature of 25 ° C., and thus the temperature detection sensitivity increases. Further, the difference between the consistency at −40 ° C. and the consistency at normal temperature of 25 ° C. is preferably 50 or more, and more preferably 150 or more.

In the above description, the filler is also filled in the slot groove and the loose tube for communication. However, the filler is for preventing water from entering or running, and is used in an environment free of these problems. In the case of an optical cable to be used, the first filling 5 is provided in a slot groove for communication or a loose tube for communication.
Need not be filled, and only the above-described second filler 7 may be filled only in the slot groove for temperature detection and the loose tube for temperature detection. When only the optical fiber for temperature detection is required, the structure of the optical cable may be a single-core optical cable originally having a space for filling the second filler 7 therein. I just need.

An optical fiber core housed in a slot groove for temperature detection or a loose tube for temperature detection does not mean that an optical signal cannot be transmitted at all. Communication with a large transmission loss compared to a normal communication line, but with no problem even if the transmission loss is large, for example, communication with a lower data transmission speed than usual, or a transmission line for a transmission line monitoring test It can be used as

In the above description, since the transmission loss is simply measured with respect to the entire length of the optical fiber core for detecting the temperature, the temperature in an environment where the temperature is substantially constant over the entire length of the optical fiber core, or the optical fiber core. In particular, in the specific section, only the temperature of the environment where the temperature is reduced and the temperature is almost constant can be measured. However, an optical time domain (OTDR), which is a measuring instrument for observing backscattered light and detecting a break point of an optical fiber core wire, etc.
Using Reflectmeter), the amount of transmission loss along the line of the optical fiber core can be detected as the slope of the optical power of the backscattered light, and the temperature distribution along the line of the optical fiber core can be determined from the amount of transmission loss. Can be detected.

[0031]

As is apparent from the above description, according to the first aspect of the present invention, there is provided an optical fiber storage portion filled with a filler so as to be in contact with the optical fiber core, However, since it has a temperature-dependent consistency that increases the transmission loss of the optical fiber core according to the temperature drop, it is possible to detect the ambient temperature by measuring the increase in the transmission loss of the optical fiber core. There is an effect that can be.

According to the second aspect of the present invention, a plurality of optical fiber storage sections are provided, and some of the optical fiber storage sections include:
The filler is filled into contact with the optical fiber, the filler having a temperature-dependent consistency that increases the transmission loss of the optical fiber in response to a decrease in temperature, and at least some other light. Since the optical fiber core is stored in the fiber housing so that the transmission loss does not increase as the temperature decreases, the temperature dependence of the consistency of the filler is used to reduce the transmission loss of the optical fiber core. By measuring the amount of increase, the ambient temperature can be detected, and the optical fiber core having the temperature sensor function can be used without increasing the transmission loss without significantly changing the conventional optical cable structure. There is an effect that it can be accommodated in the same optical cable as the core wire.

According to the third aspect of the present invention, since the packing has a consistency of −200 at −40 ° C., the transmission loss greatly increases as the temperature decreases from room temperature of 25 ° C. This has the effect of increasing the temperature detection sensitivity.

According to the fourth aspect of the present invention, since the optical fiber storage portion has a groove shape or a tubular shape, the optical fiber and the filler can be easily stored, and the filler can be removed from the storage portion. There is an effect that it is hard to come out.

According to the fifth aspect of the present invention, since the Young's modulus of the sheath of the optical fiber core housed in a part of the optical fiber housings is 70 kg / mm ² or less, Is flexible and easily affected by the consistency of the filler, and thus has the effect of increasing the temperature detection sensitivity.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical cable according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a specific example of an optical fiber used in the optical cable of the present invention.

FIG. 3 is a sectional view of an optical cable according to a second embodiment of the present invention.

FIG. 4 is a sectional view of an optical cable according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the composition and physical properties of a filler.

FIG. 6 is a diagram showing the temperature dependence of the consistency of fillings A to C and K.

[Explanation of symbols]

1 ... jacket, 2 ... holding roll, 3 ... slot rod, 4, 2
1, 32: tensile strength member, 5: first filling, 6: single-core optical fiber, 7: second filling, 16: tape-like optical fiber, 31: loose tube, 33: interposed string .

Claims (5)

[Claims] 1. An optical fiber storage part filled with a filler so as to be in contact with an optical fiber, wherein the filler is
An optical cable having a temperature-dependent consistency that increases a transmission loss of the optical fiber core according to a temperature decrease. 2. A plurality of optical fiber storage sections, wherein a part of the optical fiber storage sections is filled with a filler so as to come into contact with an optical fiber core, and the filler fills in response to a temperature decrease. The optical fiber core has a temperature-dependent consistency that increases the transmission loss of the optical fiber core, and at least some of the other optical fiber housings do not increase the transmission loss of the optical fiber core according to the temperature drop. An optical cable characterized in that it is stored in the form of an optical cable. 3. The packing has a consistency at -40 ° C. of 200
The optical cable according to claim 1, wherein: 4. The optical cable according to claim 1, wherein the optical fiber storage section has a groove shape or a tubular shape. 5. The optical fiber core housed in said part of the optical fiber housing has a Young's modulus of 70 kg / mm.
The optical cable according to any one of claims 1 to 4, wherein the number is ² or less.