JP5367652B2 - Fixing method of optical fiber temperature sensor - Google Patents

Description

The present invention is a cryogenic device such as a superconducting magnet, internal temperature measurement, such as a cryogenic container of the liquefied gas relates to the method of fixing the optical fiber temperature sensor for performing status monitoring.

  Conventionally, if cryogenic equipment such as superconducting magnets has increased heat penetration due to abnormal internal heat generation or poor heat insulation, it will not only maintain its function but also cause internal damage, requiring repair and replacement, etc. A large impact. Also, cryogenic containers of liquefied gases such as nitrogen and helium have an effect of increasing the amount of evaporation or causing the risk of breakage or leakage if internal damage or poor insulation occurs. For this reason, it is important to measure and monitor the internal temperature of these cryogenic equipment and cryogenic containers. In addition, in order to grasp the amount of liquid inside the cryogenic container, there is a demand for grasping the liquid level by measuring temperature. An optical fiber temperature sensor having an FBG (Fiber Bragg Grating) part with improved sensitivity at extremely low temperatures is effective to coat a material having a large coefficient of thermal expansion or Young's modulus, and an appropriate cross-sectional area ratio with the fiber. A technique for applying a resin coating is proposed (see Patent Document 1 below). In addition, a technique has been proposed in which the FBG portion is not coated but adhered to a Teflon (registered trademark) resin substrate having a large linear expansion coefficient, and the temperature is measured through thermal expansion and contraction of the substrate (see Non-Patent Document 1 below). ).

US Pat. No. 6,072,922

Mizunami, Kawashima, Tatsumi, “Temperature Sensing at Low Temperature Using Fiber Grating”, IEICE Technical Report OFT 2001-7, pp. 37-42

  However, in these technologies, since the FBG optical fiber temperature sensor has a large element that converts temperature from thermal expansion and contraction of the FBG part, measurement accuracy and responsiveness decrease unless sufficient heat transfer to the FBG part is ensured. However, if thermal expansion and contraction is inhibited, accurate measurement cannot be performed. Resin coatings and substrates effective in improving sensitivity have low thermal conductivity of the material, making it difficult to ensure heat transfer to the FBG part, and thermal expansion and contraction when in close contact with each other to ensure high thermal conductivity. There was a problem of inhibiting.

The present invention is, in view of the above situation, the heat transfer is easily secured to the thermal conductivity is high FBG of the material, providing a method of fixing the optical fiber temperature sensor which thermal expansion and contraction improved the good cryogenic properties The purpose is to do.

In order to achieve the above object, the present invention provides
[ 1 ] An optical fiber temperature sensor fixing method comprising: an optical fiber having an FBG portion; a resin coating layer applied on the optical fiber; and a metal material coating layer formed on the resin coating layer. The optical fiber temperature sensor has frames with high thermal conductivity on both sides in a state where no tension is applied to the optical fiber temperature sensor, and the frames are fixed to a measurement object .

[2] In the above SL (1) the method of fixing the optical fiber temperature sensor according, has a high thermal conductivity frame on one side in a state in which no tension to the optical fiber temperature sensor, to secure the frame to be measured It is characterized by that.
[3] In the above SL (1) the method of fixing the optical fiber temperature sensor according, has a high thermal conductivity frame on one side in a state in which no tension to the optical fiber temperature sensor, the optical fiber temperature sensor on the frame A protective tube is disposed so as to cover, and the protective tube is fixed in close contact with a measurement object.

According to the present invention, the following effects can be achieved.
(1) It is possible to improve measurement accuracy, responsiveness, and reproducibility by providing a sensor with high thermal conductivity while maintaining the sensitivity improvement effect of the FBG sensor at an extremely low temperature.
(2) Since no tension is applied to the FBG portion of the FBG sensor, it is possible to perform fixing with high thermal conductivity without inhibiting thermal expansion and contraction.

It is a block diagram of the optical fiber temperature sensor which comprises further the metal coating with higher heat conductivity on the FBG sensor surface which apply | coated the resin coating layer which improved the sensitivity which shows the Example of this invention. It is a figure which shows the fixing method (the 1) of the optical fiber temperature sensor which does not inhibit the expansion-contraction which shows the Example of this invention. It is a figure which shows the fixing method (the 2) of the optical fiber temperature sensor which does not inhibit the expansion-contraction which shows the Example of this invention. It is a figure which shows the fixing method (the 3) of the optical fiber temperature sensor which does not inhibit the expansion-contraction which shows the Example of this invention.

An optical fiber temperature sensor fixing method according to the present invention comprises: an optical fiber having an FBG portion; a resin coating layer applied on the optical fiber; and a metal material coating layer formed on the resin coating layer. The optical fiber temperature sensor has frames with high thermal conductivity on both sides in a state where no tension is applied to the optical fiber temperature sensor, and the frames are fixed to a measurement object .

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a block diagram of an optical fiber temperature sensor comprising a metal coating having a higher thermal conductivity on the surface of an FBG sensor to which a resin coating layer with improved sensitivity is applied, showing an embodiment of the present invention.
In this figure, 1 is an optical fiber having an FBG portion 2, 1 a is a normal optical fiber coating layer, 3 is a resin coating layer applied to the optical fiber 1, and 4 is a metal coating layer covering the resin coating layer 3. It is.

  In this way, the resin coating layer 3 in which the FBG portion 2 is coated with a resin having a high linear expansion coefficient in an appropriate thickness improves the sensitivity, and further, a metal coating layer having a high thermal conductivity on the resin coating layer 3. 4 is coated to a thickness that does not affect thermal expansion and contraction (for example, the outer diameter of the acrylic resin coating is φ0.5 mm (core wire diameter 0.125 mm, coating thickness 0.1875 mm)). Ensure heat. In this FBG sensor, only the FBG part is coated and the other part is a normal optical fiber coating 1a, so that the low thermal conductivity (low heat penetration) that is the merit of the original optical fiber temperature sensor can be maintained. .

Thus, since the optical fiber temperature sensor of this invention was comprised so that the metal coating layer 4 might be given on the resin coating layer 3, it can improve a sensitivity, ensuring high heat transfer.
FIG. 2 is a diagram showing an optical fiber temperature sensor fixing method (part 1) that does not hinder expansion and contraction according to an embodiment of the present invention, FIG. 2 (a) is a diagram showing the inside thereof, and FIG. It is a figure which shows the fixing method to a measuring object.

As shown in these drawings, the optical fiber temperature sensor of the present invention includes an optical fiber 11 having a normal optical fiber coating layer 11a provided with an FBG portion 12 similar to that shown in FIG. 1, a resin coating, and a metal covering the resin coating. In a state where the coating is loosened (no tension is applied), the coating is fixed by frames 13 and 14 having high thermal conductivity arranged on both sides, and the optical fiber temperature sensor is mounted on the measurement object 16. A resin coating layer and a metal coating covering the resin coating layer are disposed outside the frames 13 and 14. A cover 15 is disposed between the frames 13 and 14, and the frames 13 and 14 and the cover 15 are mounted on the measurement object 16.

  In this embodiment, frames 13 and 14 having high thermal conductivity are prepared, and both ends of the FBG portion of the FBG sensor shown in FIG. 1 are fixed by the frames 13 and 14 so that no tension is applied to the FBG portion. It eliminates the effects and enables accurate temperature measurement. Further, the frames 13 and 14 are fixed in close contact with the measurement object 16, and the heat transfer from the measurement object 16 to the FBG part 12 is performed by applying the coating of the present invention to the fixing part of the FBG sensor with the frames 13 and 14. To ensure measurement accuracy and responsiveness.

FIG. 3 is a diagram showing a method (part 2) for fixing an optical fiber temperature sensor that does not hinder expansion and contraction according to an embodiment of the present invention, and an optical fiber 21 having a normal optical fiber coating layer 22 a provided with an FBG portion 22. The optical fiber temperature sensor is measured so that the resin coating layer and the metal coating layer covering the resin coating layer are cantilevered fixed by a single frame 23 in a state where the resin coating layer is loosened (no tension is applied). Mount on the target 25. A resin coating layer and a metal coating layer covering the resin coating layer are disposed outside the one end 24 of the frame 23.

Thus, the same effect is acquired by hold | gripping only the one end of the FBG part of the FBG sensor shown in FIG. 1 with the flame | frame 23 with high heat conductivity, and making it closely_contact | adhere to the measuring object 25. FIG.
FIG. 4 is a diagram showing an optical fiber temperature sensor fixing method (part 3) that does not hinder expansion and contraction according to an embodiment of the present invention. FIG. 4A is a diagram showing the structure of the optical fiber temperature sensor. b) is a cross-sectional view showing a fixed state to the measurement object.

  In this embodiment, an optical fiber 31 having a normal optical fiber coating layer 31a provided with an FBG portion 32, a resin coating layer, a metal coating layer covering the resin coating layer, and an optical fiber temperature sensor having a protective tube 33 are loosened. In a state where no tension is applied, the optical fiber temperature sensor is arranged so that it is fixed by a single frame 34 and cantilevered. The optical fiber temperature sensor is fixed in close contact with the measuring object 36. A resin coating layer and a metal coating layer covering the resin coating layer are arranged outside the one end 35 of the frame 34.

As described above, the FBG sensor shown in FIG. 1 is covered with the protective tube 33 so that the FBG portion 32 is covered, and only one end is fixed, and the protective tube 33 is brought into close contact with the measurement object 36 and fixed, thereby enabling the FBG to be protected. .
3 and 4, the FBG portion of the FBG sensor may be loosened and both ends may be fixed unless tension is applied.

  By using the FBG sensor according to the present invention, a temperature sensor that improves accuracy, responsiveness, and high reproducibility in many locations while minimizing heat penetration into cryogenic equipment and cryogenic containers, and its A fixing method can be provided, and the internal temperature can be monitored more frequently and even at regular intervals. If internal temperature monitoring becomes possible in this way, it is possible to reduce the frequency of sudden shutdowns and failures during the operation of cryogenic equipment, enabling safe shutdown and appropriate inspection and repair. It can contribute to the improvement of safety and reliability.

  In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

Method of fixing the optical fiber temperature sensor of the present invention, it is possible to reduce the frequency of sudden shutdown or failure in the operation of the cryogenic equipment, can be stopped and an appropriate inspection and repair of safe operation It can contribute to the improvement of safety and reliability.

1,11,21,31 Optical fiber 1a, 11a, 22a, 31a Normal optical fiber coating layer 2, 12, 22 , 32 FBG section 3 Resin coating layer 4 Metal coating layer 13, 14 Frame 15 with high thermal conductivity Cover 16, 25, 36 Measurement object 23, 34 Single frame 24, 35 One end of frame 33 Protective tube

Claims (3)

An optical fiber having an F BG portion, and a resin coating layer applied onto the optical fiber, comprising a coating layer of a metal material formed on the resin coating layer, no tension to the optical fiber temperature sensor A method for fixing an optical fiber temperature sensor , comprising frames having high thermal conductivity on both sides in a state, and fixing the frames to a measurement object . 2. The method of fixing an optical fiber temperature sensor according to claim 1, wherein a frame having high thermal conductivity is provided on one side without applying tension to the optical fiber temperature sensor , and the frame is fixed to a measurement object. Fixing method of optical fiber temperature sensor. 2. The method of fixing an optical fiber temperature sensor according to claim 1, wherein a frame having a high thermal conductivity is provided on one side without applying tension to the optical fiber temperature sensor, and a protective tube covering the optical fiber temperature sensor is provided on the frame. An optical fiber temperature sensor fixing method comprising: arranging and fixing the protective tube in close contact with an object to be measured.

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