WO2021192116A1 - 計測装置 - Google Patents
計測装置 Download PDFInfo
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- WO2021192116A1 WO2021192116A1 PCT/JP2020/013451 JP2020013451W WO2021192116A1 WO 2021192116 A1 WO2021192116 A1 WO 2021192116A1 JP 2020013451 W JP2020013451 W JP 2020013451W WO 2021192116 A1 WO2021192116 A1 WO 2021192116A1
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- Prior art keywords
- strain
- optical fiber
- attached
- fiber sensor
- measurement target
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
- G01B5/0011—Arrangements for eliminating or compensation of measuring errors due to temperature or weight
- G01B5/0014—Arrangements for eliminating or compensation of measuring errors due to temperature or weight due to temperature
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/14—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/14—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
- G01K1/143—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations for measuring surface temperatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
- G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
Definitions
- the present disclosure relates to a technique for measuring the temperature and strain of a measurement target using an optical fiber sensor.
- Patent Document 1 a multi-point optical fiber sensor using FBG (Fiber Bragg Grating) is covered with a protective material made of fibers, hardened with resin and integrated, and then fastened to a measurement target such as a pipe.
- FBG Fiber Bragg Grating
- a measurement method for fixing using the above is described. In this measurement method, since the optical fiber sensor is firmly fixed to the measurement target, the behavior of the measurement target can be followed well and the temperature and strain can be measured accurately.
- An object of the present invention is to make it possible to easily detect temperature and strain by an optical fiber sensor even for a measurement target having a complicated shape.
- the measuring device is The cam part attached to the first position of the measurement target and A moving portion that is attached to the second position of the measurement target and can move in the expansion / contraction direction of the measurement target with respect to the cam portion.
- a strain portion that is attached to the moving portion along the measurement target and pressed against the cam portion, and the strain portion whose strain changes as the moving portion moves as the measurement target expands and contracts.
- An optical fiber sensor for temperature detection which has a temperature measuring unit for measuring temperature and is attached to the strain unit, It has a strain measuring unit for measuring strain, and includes an optical fiber sensor for strain detection attached to the strain unit.
- the optical fiber sensor is attached to the strained portion that is attached to the moving portion that can move in the expansion / contraction direction of the measurement target and is pressed against the cam portion.
- the temperature and strain can be easily detected by the optical fiber sensor even for a measurement target having a complicated shape.
- FIG. 1 The block diagram of the optical fiber sensor 10 which concerns on Embodiment 1.
- FIG. The explanatory view of the FBG sensor unit 12 which concerns on Embodiment 1.
- FIG. The graph which shows the characteristic of the reflection spectrum obtained by the FBG sensor unit 12 which concerns on Embodiment 1.
- FIG. The figure which shows the example of the calibration curve of temperature and wavelength which concerns on Embodiment 1, and the calibration curve of strain and wavelength.
- the block diagram of the measurement system 100 which concerns on Embodiment 1.
- FIG. The block diagram of the measuring apparatus 20 which concerns on Embodiment 1.
- FIG. The explanatory view of the arrangement method of the optical fiber sensor 10 in the strain part 25 which concerns on Embodiment 1.
- FIG. The explanatory view of the mounting method of the measuring apparatus 20 which concerns on Embodiment 1.
- FIG. Explanatory drawing of the fixture 221 and the fixture 241 according to the first embodiment.
- the explanatory view of the operation of the measuring apparatus 20 which concerns on Embodiment 1.
- Optical fiber sensors include multipoint optical fiber sensors and distributed optical fiber sensors.
- the multi-point optical fiber sensor can measure at a plurality of set points in one optical fiber.
- the distributed optical fiber sensor can continuously measure with one optical fiber.
- light having a wide band frequency or scattered light is used for measurement using an optical fiber. Examples of the scattered light include Rayleigh scattered light, Brillouin scattered light, and Raman scattered light.
- the optical fiber sensor 10 is an optical fiber sensor in which an FBG (Fiber Bragg Gratings) is used as a sensor unit.
- FBG Fiber Bragg Gratings
- the optical fiber sensor 10 includes a core 11, an FBG sensor portion 12 provided on the core 11, a clad 13 that covers the outer periphery of the core, and a covering portion 14 that covers the outer periphery of the clad 13. .
- the FBG sensor unit 12 is used when measuring the temperature using the relationship between the Bragg wavelength and the temperature, and when measuring the strain using the relationship between the Bragg wavelength and the strain.
- the FBG sensor unit 12 is arranged inside the core 11. Examples of the material constituting the covering portion 14 include an acrylate resin and a polyimide resin.
- the covering portion 14 is formed with a coating removing portion 15 in which the outer periphery of the clad 13 is exposed.
- the coating removing portion 15 is formed in the region of the coating portion 14 corresponding to the FBG sensor portion 12 in the radial direction of the optical fiber sensor 10. Therefore, the portion of the optical fiber sensor 10 in which the FBG sensor unit 12 is arranged has a smaller radial dimension than the other portion of the optical fiber sensor 10. Examples of the dimensions of the portion of the optical fiber sensor 10 where the covering portion 14 is located, the radial direction of the clad 13, and the radial direction of the core 11 are 250 ⁇ m (micrometer), 125 ⁇ m, and 10 ⁇ m, respectively.
- the FBG sensor unit 12 is arranged over a range of about 5 mm (millimeters) of the core 11 in the longitudinal direction of the optical fiber sensor 10.
- the FBG sensor unit 12 has a core 11 formed with a periodic bending rate modulation unit. Therefore, a steep reflection spectrum characteristic can be obtained in the FBG sensor unit 12.
- the refractive index of the core 11 changes with a period ⁇ .
- the refractive index n changes depending on the temperature of the optical fiber.
- the period ⁇ changes depending on the temperature and strain of the optical fiber. Therefore, when it is desired to measure the temperature, the strain to be measured should not be transmitted to the optical fiber, and as shown in FIG. 4, the relationship between the change in Bragg wavelength ⁇ b and the change in temperature should be measured in advance. Therefore, the temperature of the measurement target can be measured.
- the temperature in the vicinity of the measurement target is acquired, and the wavelength change due to the temperature is subtracted from the change in the Bragg wavelength ⁇ b.
- the Bragg wavelength ⁇ b change of only the strain change can be acquired, and the strain of the measurement target can be measured.
- the configuration of the measurement system 100 according to the first embodiment will be described with reference to FIG.
- the measurement system 100 includes a measuring device 20 including an optical fiber sensor 10, an optical circulator 30, an ASE (Amplified Spontaneous Emission) light source 40, and a spectrum analyzer 50.
- a measuring device 20 including an optical fiber sensor 10, an optical circulator 30, an ASE (Amplified Spontaneous Emission) light source 40, and a spectrum analyzer 50.
- the measuring device 20 includes an optical fiber sensor 10, and attaches the optical fiber sensor 10 to the measurement target.
- the optical circulator 30 is connected to the longitudinal end of the optical fiber sensor 10.
- the optical circulator 30 converts an optical path.
- the ASE light source 40 emits light having a relatively wide band frequency.
- the ASE light source 40 is connected to the optical circulator 30.
- the light emitted from the ASE light source 40 is input to the optical circulator 30.
- the spectrum analyzer 50 is a wavelength measuring device.
- the spectrum analyzer 50 is connected to the optical circulator 30. Light is input to the spectrum analyzer 50 via the optical circulator 30.
- the measurement system 100 converts the Bragg wavelength ⁇ b acquired by the spectrum analyzer 50 into temperature and strain. Thereby, the temperature and strain of the measurement target are specified.
- the configuration of the measuring device 20 according to the first embodiment will be described with reference to FIGS. 6 to 9.
- the measuring device 20 includes an optical fiber sensor 10 and a mounting device 21.
- the attachment device 21 is a device for attaching the optical fiber sensor 10 to the measurement target 110.
- the mounting device 21 includes a cam portion 22, a track portion 23, a moving portion 24, and a strain portion 25.
- the measurement target 110 is a pipe used for equipment such as a refrigeration cycle and an artificial satellite.
- the measurement target 110 is not limited to the piping, and may be any object for measuring temperature and strain.
- the measurement target 110 may be distorted in the longitudinal direction, that is, may expand and contract.
- the cam portion 22 is attached to the first position 111 of the measurement target 110.
- the cam portion 22 is attached to the first position 111 by the attachment 221.
- the cam portion 22 is adapted so that the surface on which the strain portion 25, which will be described later, is pressed, moves away from the moving portion 24 as the distance from the measurement target 110 increases.
- the surface on which the strain portion 25 is pressed is a curved surface.
- the track portion 23 is attached to the cam portion 22 in parallel with the longitudinal direction of the measurement target 110.
- the moving portion 24 is attached to the second position 112 of the measurement target 110 and is attached to the orbital portion 23 so as to be movable along the orbital portion 23.
- the moving portion 24 can move with respect to the cam portion 22 in the expansion / contraction direction of the measurement target.
- the moving portion 24 is attached to the second position 112 by the attachment 241.
- the moving portion 24 is attached to the track portion 23 via the rotating portion 242.
- the rotating portion 242 rotates according to the expansion and contraction of the measurement target 110, so that the moving portion 24 moves along the track portion 23.
- the moving portion 24 may have another configuration in which the moving portion 24 slides and moves using the track portion 23 as a guide.
- the strain portion 25 is attached to the moving portion 24 along the measurement target 110 and pressed against the cam portion 22.
- the strain of the strain portion 25 changes as the moving portion 24 moves as the measurement target 110 expands and contracts.
- the strain portion 25 is a leaf spring.
- the strain portion 25, which is a leaf spring is moved to the moving portion 24 so that the tip portion 251 is pressed against the cam portion 22 and the root portion 252 to the intermediate portion 253 are in contact with the measurement target 110. It is attached.
- the moving portion 24 moves as the measurement target 110 expands and contracts, so that the cam portion 22 changes the strain in the vicinity of the tip portion 251 of the leaf spring.
- the optical fiber sensor 10 is composed of one optical fiber.
- the optical fiber sensor 10 has two types of FBG sensor units 12, a temperature measuring unit 16 for measuring temperature and a strain measuring unit 17 for measuring strain. That is, in the first embodiment, one optical fiber sensor 10 also serves as a temperature detection optical fiber sensor having a temperature measuring unit 16 and a strain detecting optical fiber sensor having a strain measuring unit 17. ..
- the temperature measuring unit 16 is located between the root portion 252 and the intermediate portion 253 of the strain portion 25, and the strain measuring unit 17 is located between the intermediate portion 253 and the tip portion 251. It is attached to the strain portion 25. At this time, as shown in FIG.
- the optical fiber sensor 10 is attached to the strain portion 25 in a state in which the vicinity of the temperature measuring portion 16 is bent. Further, the optical fiber sensor 10 is attached to the strain unit 25 in a state where the strain measurement unit 17 is in contact with the strain unit 25 without bending in the vicinity of the strain measurement unit 17. It is conceivable that the optical fiber sensor 10 is bent in the vicinity of the temperature measuring unit 16 in a wavy or circumferential shape. If the optical fiber sensor 10 is bent, the temperature measuring unit 16 portion may float from the measurement target 110, and the temperature may not be measured accurately. Therefore, it is desirable to apply grease or the like to the vicinity of the temperature measuring unit 16 to fill the gap between the temperature measuring unit 16 and the strained unit 25. At this time, it is necessary to apply an adhesive or the like so that the temperature measuring unit 16 is not completely fixed to the strained unit 25.
- the strain is specified by subtracting the wavelength change due to temperature from the change in Bragg wavelength ⁇ b detected by the strain measuring unit 17. Therefore, since it is necessary to specify the temperature in the vicinity of the strain measuring unit 17, the strain measuring unit 17 is arranged in the vicinity of the temperature measuring unit 16. It is necessary to transmit the strain generated in the strain unit 25, which is a leaf spring, to the strain measuring unit 17. Therefore, the strain measuring unit 17 is completely fixed to the strain unit 25 with an adhesive or the like. However, the strain measuring unit 17 is fixed to the strain unit 25, and is not directly fixed to the measurement target 110. Therefore, the optical fiber sensor 10 can be used repeatedly by removing the measuring device 20 from the measuring target 110 and attaching it to another measuring target 110.
- the strained portion 25 is made of a highly heat conductive material in order to prevent the heat transferred to the strained portion 25 from escaping.
- the elements other than the strain portion 25 included in the mounting device 21 are made of a low thermal conductive material.
- the strain portion 25 is 200 W / m ⁇ K or more, and the elements other than the strain portion 25 included in the mounting device 21 are 20 W / m ⁇ K or less.
- An example of a high thermal conductive material is copper, and an example of a low thermal conductive material is fiber reinforced plastic, ceramic, wood, and the like.
- the strain portion 25 has high rigidity from the root portion 252 to the intermediate portion 253 where the temperature measuring unit 16 is arranged, and has low rigidity from the intermediate portion 253 to the tip portion 251 where the strain measuring unit 17 is arranged.
- the portion where the temperature measuring unit 16 is arranged becomes difficult to separate from the measurement target 110, and the portion where the strain measuring unit 17 is arranged tends to be distorted.
- As a method of increasing the rigidity it is conceivable to increase the width as shown in FIG. Further, the thickness may be increased. On the contrary, as a method of lowering the rigidity, it is conceivable to narrow the width as shown in FIG. Further, the thickness may be reduced.
- the strain portion 25, which is a leaf spring may be warped toward the measurement target 110 in advance.
- the strain portion 25, which is a leaf spring is naturally pressed against the measurement target 110, and the portion of the strain portion 25 where the temperature measurement unit 16 is arranged is the measurement target 110. It becomes easier to contact.
- the optical fiber sensor 10 is arranged along the track portion 23 and the moving portion 24 from the start point side. Subsequently, as shown in FIGS. 6 and 7, the optical fiber sensor 10 is arranged from the moving portion 24 to the outside of the strained portion 25. At this time, the temperature measuring unit 16 is arranged between the root portion 252 and the intermediate portion 253 on the outside of the strain portion 25, and the strain measuring unit 17 is located between the intermediate portion 253 and the tip portion 251 on the outside of the strain portion 25. Be placed. Subsequently, the optical fiber sensor 10 is arranged from the tip portion 251 of the strain portion 25 to the measurement target 110 side of the strain portion 25, passing through the measurement target 110 side of the strain portion 25 to the moving portion 24.
- the optical fiber sensor 10 is arranged along the moving portion 24 and the track portion 23. After that, the optical fiber sensor 10 is arranged along the track portion 23 and the moving portion 24 from the start point side of the next mounting device 21.
- the optical fiber sensor 10 it is necessary to bend the optical fiber sensor 10. At this time, it is desirable to give the optical fiber sensor 10 a roundness so that the radius of curvature does not become too small.
- the measuring device 20 is attached to the complicatedly bent pipe which is the measurement target 110.
- the measuring device 20 includes a plurality of mounting devices 21.
- the optical fiber sensor 10 has a plurality of pairs of a temperature measuring unit 16 and a strain measuring unit 17. Each of the plurality of pairs of the temperature measuring unit 16 and the strain measuring unit 17 is attached to the strain unit 25 of each of the plurality of mounting devices 21. Then, each of the plurality of attachment devices 21 is attached to the measurement target 110.
- the temperature and strain can be measured by one optical fiber sensor 10 at a plurality of locations of the measurement target 110.
- the temperature measuring unit 16 and the strain measuring unit 17 are arranged on the surface opposite to the measuring object 110 in order to prevent the optical fiber sensor 10 from being damaged.
- the optical fiber sensor 10 is also passed through the measurement target 110 side of the strain portion 25.
- a groove 113 is formed on the surface of the strain portion 25 on the measurement target 110 side, and the optical fiber sensor is laid in the groove 113. Therefore, the optical fiber sensor 10 is prevented from being damaged even on the measurement target 110 side of the strain portion 25.
- the optical fiber sensor 10 is easily broken by itself. Therefore, it is desirable to attach the optical fiber sensor 10 to the attachment device 21 after taking measures such as covering the periphery of the optical fiber sensor 10 or putting it in a protective tube.
- the configuration of the fixture 221 and the fixture 241 according to the first embodiment will be described with reference to FIG.
- the attachment 221 and the attachment 241 are devices for attaching the attachment device 21 to the measurement target 110.
- the configuration of the fixture 221 is shown in FIG. 9, the fixture 241 has the same configuration as the fixture 221.
- the fixture 221 will be described.
- the tip 222 of the fixture 221 is formed in a hook shape.
- the fixture 221 is configured to attract the hook-shaped tip 222 to the handle 224 side by the spring 223.
- the mounting device 21 can be attached to the large measurement target 110 as shown on the left side of FIG. 9, and the mounting device 21 can be attached to the small measurement target 110 as shown on the right side of FIG. Is.
- the lever 225 When attaching, the lever 225 may be pulled toward the measurement target 110 to spread the hook-shaped tip 222, and the measurement target 110 may be sandwiched between the hook-shaped tip 222 and the handle 224.
- the fixture 221 When the size of the measurement target 110 is substantially constant, the fixture 221 may have a shape like a clothespin.
- the temperature measuring unit 16 detects a change in the Bragg wavelength ⁇ b due to a change in the temperature of the measurement target 110.
- the optical fiber sensor 10 is flexed and arranged in the vicinity of the temperature measuring unit 16. Therefore, when the distance between the first position 111 and the second position 112 of the measurement target 110 is extended and the state on the right side of FIG. 10 is reached, the deflection of the optical fiber sensor 10 is extended according to the extension of the measurement target 110.
- the temperature measuring unit 16 is prevented from being separated from the strained unit 25. That is, in the vicinity of the temperature measuring unit 16, it is prevented from following the change in strain due to the deflection. As a result, an appropriate temperature can be measured even when the state on the right side of FIG. 10 is reached.
- FIG. 10 the case where the measurement target 110 is extended is shown.
- the temperature and strain can be measured.
- the moving portion 24 attached to the second position 112 moves in a direction approaching the cam portion 22 as the measurement target 110 shrinks.
- the strain of the strain portion 25 which is a leaf spring, changes.
- the Bragg wavelength ⁇ b detected by the strain measuring unit 17 changes.
- the measurement system 100 identifies the strain of the measurement target 110 by subtracting the wavelength change due to the temperature detected by the temperature measuring unit 16 from the change of the Bragg wavelength ⁇ b.
- the measuring device 20 is attached to the moving portion 24 that can move in the expansion / contraction direction of the measurement target 110, and the optical fiber sensor 10 is attached to the strained portion 25 pressed against the cam portion 22. It is attached. As a result, the temperature and strain can be easily measured at a plurality of locations by the optical fiber sensor 10 even for the measurement target 110 having a complicated shape.
- the measuring device 20 according to the first embodiment can measure the temperature and the strain separately by arranging the temperature measuring unit 16 and the strain measuring unit 17 in the vicinity thereof.
- the measuring device 20 according to the first embodiment is arranged so that the optical fiber sensor 10 bends in the vicinity of the temperature measuring unit 16. As a result, the influence of strain on the temperature measuring unit 16 is prevented, and the temperature can be measured appropriately. As a result, the strain can be measured appropriately.
- thermocouples and strain gauges can only measure at a single point. Therefore, when the number of measurement points increases, the wiring becomes cluttered and the work man-hours for attachment / detachment also increase.
- the measuring device 20 according to the first embodiment can easily and highly accurately measure the temperature and strain at a plurality of locations even for the measurement target 110 having a complicated shape such as a pipe. ..
- a pipe is used as the measurement target 110.
- the measurement target 110 is not limited to the piping, and may be another object as long as it is necessary to measure the temperature and strain.
- an optical fiber sensor 10 provided with an FBG sensor unit 12 is used.
- the optical fiber sensor 10 is not limited to the one provided with the FBG sensor unit 12, and may be another multi-point type optical fiber sensor or a distributed type optical fiber sensor.
- one optical fiber sensor 10 serves both as a temperature detection optical fiber sensor having a temperature measuring unit 16 and a strain detecting optical fiber sensor having a strain measuring unit 17.
- the optical fiber sensor for temperature detection having the temperature measuring unit 16 and the optical fiber sensor for strain detection having the strain measuring unit 17 may be used as separate optical fiber sensors.
- ⁇ Modification example 4> In FIG. 8, a case where one optical fiber sensor 10 is used to measure the temperature and strain at a plurality of locations for one measurement target 110 has been described. However, the temperature and strain at a plurality of locations may be measured by using a plurality of optical fiber sensors 10 for one measurement target 110. For example, as described in the third modification, the optical fiber sensor 10 for temperature measurement and the optical fiber sensor 10 for strain measurement may be prepared separately. Further, the optical fiber sensor 10 in a part of the measurement target 110 may be arranged, and another optical fiber sensor 10 may be arranged in the remaining section.
- Optical fiber sensor 11 core, 12 FBG sensor part, 13 clad, 14 covering part, 15 coating removing part, 16 temperature measuring part, 17 strain measuring part, 20 measuring device, 21 mounting device, 22 cam part, 221 mounting tool 222 tip, 223 spring, 224 handle, 225 lever, 23 track part, 24 moving part, 241 fixture, 25 strain part, 251 tip part, 252 root part, 253 middle part, 30 optical circulator, 40 ASE light source, 50 Spectrum analyzer, 100 measurement system, 110 measurement target, 111 first position, 112 second position, 113 groove.
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Abstract
Description
この発明は、複雑な形状の計測対象についても、光ファイバセンサにより温度及びひずみを容易に検出可能にすることを目的とする。
計測対象の第1位置に取り付けられたカム部と、
前記計測対象の第2位置に取り付けられ、前記カム部に対して前記計測対象の伸縮方向に移動可能な移動部と、
前記計測対象に沿うように前記移動部に取り付けられ前記カム部に押し付けられたひずみ部であって、前記計測対象の伸縮に伴い前記移動部が移動することによりひずみが変化するひずみ部と、
温度を計測する温度計測部を有し、前記ひずみ部に取り付けられた温度検出用の光ファイバセンサと、
ひずみを計測するひずみ計測部を有し、前記ひずみ部に取り付けられたひずみ検出用の光ファイバセンサと
を備える。
***構成の説明***
図1から図4を参照して、実施の形態1に係る光ファイバセンサ10の構成を説明する。
光ファイバセンサには、多点型の光ファイバセンサと分布型の光ファイバセンサとがある。多点型の光ファイバセンサは、1本の光ファイバにおける設定された複数の点において、計測が可能である。分布型の光ファイバセンサは、1本の光ファイバにおいて、連続的に計測が可能である。光ファイバを用いた計測には、広帯域の周波数の光又は散乱光が用いられる。散乱光としては、例えば、レイリー散乱光と、ブリルアン散乱光と、ラマン散乱光とが挙げられる。
実施の形態1では、光ファイバセンサ10は、FBG(Fiber Bragg Gratings)がセンサ部として用いられた光ファイバセンサであるとする。
FBGセンサ部12は、ブラッグ波長と温度との関係を用いて温度を計測する際、及び、ブラッグ波長とひずみとの関係を用いてひずみを計測する際に用いられる。FBGセンサ部12は、コア11の内部に配置されている。被覆部14を構成する材料としては、例えば、アクリレート樹脂と、ポリイミド樹脂と等が挙げられる。
光ファイバセンサ10における被覆部14がある部分の径方向と、クラッド13の径方向と、コア11の径方向との寸法の一例としては、それぞれ、250μm(マイクロメートル)、125μm、10μmである。FBGセンサ部12は、光ファイバセンサ10の長手方向における、コア11の5mm(ミリメートル)程度の範囲に渡って配置されている。
ブラッグ波長λbと、周期Λと、屈折率nとの関係は、下記の式1で表される。
(式1)
λb=2nΛ
したがって、温度を計測したい場合、計測対象のひずみが光ファイバに伝達しないような構成とし、図4に示すように、ブラッグ波長λbの変化と温度の変化との関係を予め計測しておくことにより、計測対象の温度を計測できる。一方、ひずみを計測したい場合、計測対象の近傍の温度を取得し、ブラッグ波長λbの変化から温度による波長変化分を差し引く。これにより、ひずみ変化のみのブラッグ波長λb変化を取得でき、計測対象のひずみを計測できる。
計測システム100は、光ファイバセンサ10を備える計測装置20と、光サーキュレータ30と、ASE(Amplified Spontaneous Emission)光源40と、スペクトラムアナライザ50とを備える。
計測システム100は、スペクトラムアナライザ50で取得されたブラッグ波長λbを温度及びひずみに換算する。これにより、計測対象の温度及びひずみが特定される。
計測装置20は、光ファイバセンサ10と、取付装置21とを備える。取付装置21は、光ファイバセンサ10を計測対象110に取り付ける装置である。取付装置21は、カム部22と、軌道部23と、移動部24と、ひずみ部25とを備える。
実施の形態1では、計測対象110は、冷凍サイクル及び人工衛星といった機器に用いられる配管であるとする。なお、計測対象110は、配管に限らず、温度及びひずみの計測対象となる物であればよい。実施の形態1では、計測対象110は、長手方向にひずみが生じる、つまり伸縮する可能性があるとする。
図6では、移動部24は、取付具241によって第2位置112に取り付けられている。また、図6では、移動部24は、回転部242を介して、軌道部23に取り付けられる。図6では、計測対象110の伸縮に応じて回転部242が回転することにより、移動部24が軌道部23に沿って移動する。なお、移動部24は、軌道部23をガイドとしてスライドして移動するような他の構成であってもよい。
実施の形態1では、ひずみ部25は、板バネである。実施の形態1では、先端部251がカム部22に押し付けられ、根本部252から中間部253までが計測対象110に接した状態になるように、板バネであるひずみ部25が移動部24に取り付けられる。これにより、計測対象110の伸縮に伴い移動部24が移動することにより、カム部22により板バネの先端部251付近のひずみが変化する。
光ファイバセンサ10は、温度計測部16がひずみ部25における根本部252から中間部253までの間に位置し、ひずみ計測部17が中間部253から先端部251までの間に位置するように、ひずみ部25に取り付けられる。この際、図7に示すように、光ファイバセンサ10は、温度計測部16の付近がたわんだ状態でひずみ部25に対して取り付けられる。また、光ファイバセンサ10は、ひずみ計測部17の付近がたわまず、ひずみ計測部17がひずみ部25に接した状態でひずみ部25に対して取り付けられる。
温度計測部16の付近での光ファイバセンサ10のたわませ方は、波状又は円周状にするといったことが考えられる。光ファイバセンサ10をたわませると、温度計測部16部分が計測対象110から浮いてしまい、温度を正確に計測できない恐れがある。そのため、温度計測部16の付近にグリース等を塗って、温度計測部16とひずみ部25との隙間を埋めることが望ましい。この際、接着剤等を塗って温度計測部16がひずみ部25に完全に固定されることがないようにする必要がある。
板バネであるひずみ部25に生じたひずみがひずみ計測部17に伝わるようにする必要がある。そのため、ひずみ計測部17は、接着剤等でひずみ部25に完全に固定される。しかし、ひずみ計測部17は、ひずみ部25に固定されるのであり、計測対象110に直接固定される訳ではない。そのため、計測装置20を計測対象110から取り外して他の計測対象110に取り付けることにより、光ファイバセンサ10を繰り返し使用することが可能である。
剛性を高くする方法としては、図7に示すように幅を広くすることが考えられる。また、厚みを厚くしてもよい。逆に、剛性を低くする方法としては、図7に示すように幅を狭くすることが考えられる。また、厚みを薄くしてもよい。
その他、予め板バネであるひずみ部25を計測対象110の方に反らせておいてもよい。これにより、計測装置20を計測対象110へ取り付けた場合に、自ずと板バネであるひずみ部25が計測対象110へ押し当てられ、ひずみ部25における温度計測部16が配置される部分が計測対象110に接触しやすくなる。
軌道部23と移動部24とひずみ部25とに沿って光ファイバセンサ10を配置する場合には、光ファイバセンサ10を曲げる必要がある。この際、光ファイバセンサ10の曲率半径が小さくなりすぎないように、丸みを持たせることが望ましい。
図8では、計測装置20は、複数の取付装置21を備えている。また、光ファイバセンサ10は、温度計測部16とひずみ計測部17との複数のペアを有する。温度計測部16とひずみ計測部17との複数のペアそれぞれが複数の取付装置21それぞれが有するひずみ部25に取り付けられる。そして、複数の取付装置21それぞれが、計測対象110に取り付けられる。
これにより、計測対象110の複数の箇所について、1本の光ファイバセンサ10によって温度及びひずみを計測可能である。
また、実施の形態1では、ひずみ部25の計測対象110側にも光ファイバセンサ10が通される。ひずみ部25の計測対象110側の面に溝113が形成されており、この溝113の中に光ファイバセンサが這わされて配置される。そのため、ひずみ部25の計測対象110側においても、光ファイバセンサ10が傷つくことが防止される。
光ファイバセンサ10は、単体では折れ易い。そのため、光ファイバセンサ10の周囲を被覆する、あるいは、保護管に入れる等の対策をした上で、取付装置21に取り付けることが望ましい。
取付具221及び取付具241は、取付装置21を計測対象110に取り付けるための装置である。図9では、取付具221の構成が示されているが、取付具241も取付具221と同じ構成である。ここでは、取付具221について説明する。
取付具221は、先端222がフック状に形成されている。取付具221は、バネ223によってフック状の先端222を取っ手224側に引き付ける構成になっている。これにより、図9の左側に示すように大きな計測対象110に対しても取付装置21を取り付け可能であり、図9の右側に示すように小さな計測対象110に対しても取付装置21を取り付け可能である。取り付けする場合には、レバー225を計測対象110側に引いて、フック状の先端222を広げ、フック状の先端222と取っ手224との間に計測対象110を挟み込めばよい。
なお、計測対象110の大きさがほぼ一定の場合には、取付具221は、洗濯バサミのような形状であってもよい。
図10を参照して、実施の形態1に係る計測装置20の動作を説明する。
計測装置20を計測対象110に取り付けた時点では、図10の左側の状態であったとする。その後、計測対象110の第1位置111と第2位置112との間が伸びたとする。
すると、図10の右側の状態になる。つまり、第2位置112に取り付けられた移動部24が計測対象110が伸びたのに合わせてカム部22から離れる方向に移動する。これにより、板バネであるひずみ部25のひずみが変化する。その結果、ひずみ計測部17によって検出されるブラッグ波長λbが変化する。計測システム100は、このブラッグ波長λbの変化から、温度計測部16によって検出される温度による波長変化分を差し引いて、計測対象110のひずみを特定する。
ここで、光ファイバセンサ10は温度計測部16の付近でたわんで配置されている。そのため、計測対象110の第1位置111と第2位置112との間が伸び、図10の右側の状態になった場合には、計測対象110の伸びに応じて光ファイバセンサ10のたわみが伸びることにより、温度計測部16がひずみ部25から離れることが防止される。つまり、温度計測部16の付近では、たわみにより、ひずみの変化に追従することが防止される。これにより、図10の右側の状態になった場合であっても、適切な温度を計測可能である。
具体的には、計測対象110が縮んだ場合には、第2位置112に取り付けられた移動部24が計測対象110が縮んだのに合わせてカム部22に近づく方向に移動する。これにより、板バネであるひずみ部25のひずみが変化する。その結果、ひずみ計測部17によって検出されるブラッグ波長λbが変化する。計測システム100は、このブラッグ波長λbの変化から、温度計測部16によって検出される温度による波長変化分を差し引いて、計測対象110のひずみを特定する。
以上のように、実施の形態1に係る計測装置20は、計測対象110の伸縮方向に移動可能な移動部24に取り付けられ、カム部22に押し付けられたひずみ部25に、光ファイバセンサ10が取り付けられる。これにより、複雑な形状の計測対象110についても、光ファイバセンサ10により複数の箇所で温度及びひずみを容易に計測可能にできる。
特に、実施の形態1に係る計測装置20は、温度計測部16の付近で光ファイバセンサ10がたわむように配置される。これにより、温度計測部16にひずみの影響が出ることが防止され、適切に温度を計測可能である。その結果、適切にひずみを計測可能である。
<変形例1>
実施の形態1では、計測対象110として配管を用いた。しかし、計測対象110は配管に限られるものではなく、温度及びひずみの計測が必要なものであれば、他の物であってもよい。
実施の形態1では、FBGセンサ部12を備えた光ファイバセンサ10を用いた。しかし、光ファイバセンサ10は、FBGセンサ部12を備えたものに限らず、他の多点型の光ファイバセンサ、又は、分布型の光ファイバセンサであってもよい。
実施の形態1では、1本の光ファイバセンサ10が、温度計測部16を有する温度検出用の光ファイバセンサと、ひずみ計測部17を有するひずみ検出用の光ファイバセンサとを兼ねた。しかし、温度計測部16を有する温度検出用の光ファイバセンサと、ひずみ計測部17を有するひずみ検出用の光ファイバセンサとを別々の光ファイバセンサとしてもよい。
図8では、1つの計測対象110に対して、1本の光ファイバセンサ10を用いて、複数の箇所の温度及びひずみを計測する場合を説明した。しかし、1つの計測対象110に対して、複数の光ファイバセンサ10を用いて、複数の箇所の温度及びひずみを計測してもよい。例えば、変形例3で説明したように、温度計測用の光ファイバセンサ10と、ひずみ計測用の光ファイバセンサ10とを別々に用意してもよい。また、計測対象110における一部の区間にある光ファイバセンサ10を配置し、残りの区間に別の光ファイバセンサ10を配置してもよい。
Claims (8)
- 計測対象の第1位置に取り付けられたカム部と、
前記計測対象の第2位置に取り付けられ、前記カム部に対して前記計測対象の伸縮方向に移動可能な移動部と、
前記計測対象に沿うように前記移動部に取り付けられ前記カム部に押し付けられたひずみ部であって、前記計測対象の伸縮に伴い前記移動部が移動することによりひずみが変化するひずみ部と、
温度を計測する温度計測部を有し、前記ひずみ部に取り付けられた温度検出用の光ファイバセンサと、
ひずみを計測するひずみ計測部を有し、前記ひずみ部に取り付けられたひずみ検出用の光ファイバセンサと
を備える計測装置。 - 前記温度検出用の光ファイバセンサは、前記温度計測部の付近がたわんだ状態で前記ひずみ部に対して取り付けられた
請求項1に記載の計測装置。 - 前記ひずみ検出用の光ファイバセンサは、前記ひずみ計測部が前記ひずみ部に接した状態で前記ひずみ部に対して取り付けられた
請求項1又は2に記載の計測装置。 - 前記ひずみ部は、先端部が前記カム部に押し付けられ、根本部から中間部までが前記計測対象に接した板バネであり、
前記温度検出用の光ファイバセンサは、前記温度計測部が前記根本部から前記中間部までの間に位置するように取り付けられ、
前記ひずみ検出用の光ファイバセンサは、前記ひずみ計測部が前記中間部から前記先端部までの間に位置するように取り付けられた
請求項1から3までのいずれか1項に記載の計測装置。 - 前記板バネは、前記根本部から前記中間部までの剛性に比べ、前記中間部から前記先端部までの剛性が低い
請求項4に記載の計測装置。 - 前記ひずみ部は、前記カム部及び前記移動部と比べて熱伝導率が高い
請求項1から5までのいずれか1項に記載の計測装置。 - 前記計測装置は、さらに、
前記計測対象に平行に、前記カム部に取り付けられた軌道部
を備え、
前記移動部は、前記計測対象の第2位置に取り付けられるとともに、前記軌道部に沿って移動可能に前記軌道部に取り付けられた
請求項1から6までのいずれか1項に記載の計測装置。 - 前記計測装置は、前記カム部と前記移動部と前記ひずみ部とを有する複数の取付装置を備え、
前記温度検出用の光ファイバセンサと、前記ひずみ検出用の光ファイバセンサとは、1本の光ファイバセンサによって構成され、
前記1本の光ファイバセンサは、前記温度計測部と前記ひずみ計測部との複数のペアを有し、前記複数のペアそれぞれが前記複数の取付装置それぞれが有する前記ひずみ部に取り付けられた
請求項1から7までのいずれか1項に記載の計測装置。
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| EP20926423.3A EP4130695A4 (en) | 2020-03-25 | 2020-03-25 | Measurement device |
| US17/795,231 US20230048107A1 (en) | 2020-03-25 | 2020-03-25 | Measurement device |
| PCT/JP2020/013451 WO2021192116A1 (ja) | 2020-03-25 | 2020-03-25 | 計測装置 |
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| WO2010123566A1 (en) * | 2009-04-22 | 2010-10-28 | Lxdata Inc. | Pressure sensor arrangement using an optical fiber and methodologies for performing an analysis of a subterranean formation |
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| EP4130695A1 (en) | 2023-02-08 |
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