WO2012129625A2 - Fiber optic magnetic force sensor, method for manufacturing same and use thereof - Google Patents

Fiber optic magnetic force sensor, method for manufacturing same and use thereof Download PDF

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Publication number
WO2012129625A2
WO2012129625A2 PCT/BR2012/000086 BR2012000086W WO2012129625A2 WO 2012129625 A2 WO2012129625 A2 WO 2012129625A2 BR 2012000086 W BR2012000086 W BR 2012000086W WO 2012129625 A2 WO2012129625 A2 WO 2012129625A2
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WO
WIPO (PCT)
Prior art keywords
magnet
sensor
sensor according
magnetic
optical fiber
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PCT/BR2012/000086
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French (fr)
Portuguese (pt)
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WO2012129625A3 (en
Inventor
Antonio Carlos Oliveira Bruno
Clara Johanna PACHECO
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Facultades Católicas, Associação Sem Fins Lucrativos, Mantenedora Da Pontificia Universidad Católica Do Rio De Janeiro -Puc Rio
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Publication of WO2012129625A2 publication Critical patent/WO2012129625A2/en
Publication of WO2012129625A3 publication Critical patent/WO2012129625A3/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35309—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer
    • G01D5/35316—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer using a Bragg gratings

Definitions

  • the invention belongs to the field of electronic and materials engineering. More specifically, the invention describes a Bragg Grating Optical Fiber (FBG) -based magnetic force sensor, as well as its manufacturing process and its use.
  • FBG Bragg Grating Optical Fiber
  • the invention is advantageously applied for monitoring the position, displacement, vibration and deformation of structures made of iron / steel, and also for monitoring corrosion in towers, structures and equipment used in the generation and transmission of electricity and in the oil and gas industry.
  • US 5,680,489 describes an optical system for detecting signals from many FBG sensors and some detectors.
  • the present invention differs from said document, among other technical reasons, in that it describes a sensor using a permanent magnet bonded to the optical fiber, rather than using a multi-layer magnetostrictive material.
  • WO 2010/009340 describes sensors with physical contact with the structure to be monitored.
  • the present invention differs from said document, among other technical reasons, in that it does not require physical contact with the structure to be monitored.
  • US 7,406,218 differs from the present invention, among other technical reasons, in that it relates to the optical detection system, while the present invention relates to the transducer.
  • the present invention provides the use of any optical system to detect Bragg network wavelength variations.
  • the present invention provides a magnetic force sensor, its obtaining process and its use.
  • the sensors of the invention are improved compared to conventional sensors, where the result of transduction is an electrical voltage.
  • Another object of the invention is a sensor with lower sensitivity to connection failure.
  • Another object of the invention is a low weight, small size and low cost sensor.
  • Another object of the invention is a sensor that provides multiplexing.
  • Another object of the invention is a sensor that provides remote sensing without the need for batteries at the measurement site.
  • the present invention provides a new type of FBG sensor.
  • the sensor comprises: i) at least one magnet; and ii) at least one optical fiber containing a Bragg network.
  • the senor further comprises: iii) an encapsulation means made of non-magnetic material.
  • the magnet of said sensor is cylindrical. In a preferred embodiment, the magnet of said sensor contains iron in its composition. In a preferred embodiment, the magnet of said sensor is of a material containing Nd. In a preferred embodiment, the magnet of said sensor is of a B-containing material. In a preferred embodiment, the magnet of said sensor is of NdFeB. In a preferred embodiment, the magnet of said sensor contains Sm. Preferred embodiment, the magnet of said sensor is of a Co-containing material. In a preferred embodiment, the magnet of said sensor is of SmCo.
  • said magnet is provided with at least one through hole.
  • the present invention consists of a new type of optical-magnetic sensor interrogated by an FBG.
  • the sensor preferably comprises: i) NdFeB cylindrical magnet with a central through hole; ii) optical fiber containing a Bragg mesh fixed to the inside of the magnet with glue; iii) non-magnetic encapsulation made with a central guide that allows the magnet to move inside.
  • Another object of the invention is a process for manufacturing FBG sensors. Said process comprises the steps of:
  • It is another object of the invention to use a magnetic-optical sensor comprising: i) at least one magnet; and ii) at least one optical fiber containing a Bragg network for producing a position monitoring, deformation, displacement, vibration and / or corrosion monitoring system for metal structures.
  • the invention is advantageously applied for monitoring the position, displacement, vibration and deformation of structures made of iron / steel, as well as for monitoring corrosion in towers, structures and equipment used in power generation and transmission and in industry. of oil and gas.
  • Figure 1 shows a schematic drawing of a preferred embodiment of a magnetic force sensor to the optical fiber, where (a) means optical fiber, (b) means fiber fixation, (c) means encapsulation, (d) means Bragg network, (e) means guide, and (f) means micro magnet.
  • Figure 2 shows the responses of a preferred sensor embodiment for 3 different magnetic forces, where (a) means power in dBm, and (b) means wavelength in nm.
  • Figure 3 shows the calibration curve of the VS wavelength range. Magnetic force, where (a) means measured, (b) means fit, and (c) means force in Newton.
  • Figure 4 shows the image obtained with the sensor scanning the area over the corrosion pit.
  • Figure 5 shows the image obtained with the sensor scanning the area over the natural corrosion pit.
  • Annex 1 shows the photo of a preferred sensor embodiment.
  • Annex 2 shows a photo of a preferred embodiment of sensor and fiber optic cable.
  • Annex 3 shows a picture of a corrosion pit made of a 1020 sheet steel.
  • Annex 4 shows a picture of a naturally corrosion pit in a steel plate used in oil storage tanks.
  • Annex 5 shows a photo of a preferred embodiment of the invention of an FBG array containing 4 sensors.
  • the present invention provides a magnetic force sensor, its obtaining process and its use.
  • the sensor comprises: i) at least one magnet; and ii) at least one optical fiber containing a Bragg network.
  • the inventive concept common to the various objects of the invention is the combination of a magnetic element with an optical fiber containing a Bragg network.
  • Fiber-based sensors with Bragg networks can be used directly to measure quantities such as stress, strain, temperature and pressure.
  • other physical quantities can be measured, such as magnetic field, electric current, position, etc.
  • the transduction of the quantity to be measured is done in wavelength. This has numerous advantages when comparing these sensors with conventional sensors where the transduction result is an electrical voltage. These advantages include immunity to electromagnetic interference, lower sensitivity to connection failure, low weight and small size, low cost, ease of multiplexing, as well as remote sensing without the need for batteries at the measurement site.
  • the present invention provides a new type of magnetic force sensor interrogated by an FBG.
  • the sensor comprises: i) NdFeB cylindrical magnet with a central through hole with a diameter of 0.5 mm, an outside diameter ranging from 1.0 to 10.0 mm and a length ranging from 1, 0 to 10 mm, depending on desired sensitivity and resolution; ii) optical fiber containing a Bragg mesh fixed to the inside of the magnet with glue or general purpose adhesives, preferably for adhesion of metal substrates, preferably cyanoacrylates, primarily Loctite 496; iii) encapsulation made of non-magnetic material, preferably acrylic, Teflon, glass or resin, with a central guide that allows the magnet to move inside.
  • the part of the optical fiber above the Bragg mesh is glued to the upper end of the package. It is enough that the array is within millimeters of any ferromagnetic structure, or in a magnetic field gradient region, for the sensor to produce a response ( Figure 2).
  • the magnet of said sensor contains iron in its composition.
  • the magnet of said sensor is of a material containing Nd.
  • the magnet of said sensor is of a B-containing material.
  • the magnet of said sensor is of NdFeB.
  • the magnet of said sensor contains Sm.
  • the magnet of said sensor is of a Co-containing material.
  • the magnet of said sensor is of SmCo.
  • the magnetic force arising from the interaction between the magnet and the ferromagnetic structure or field source to be monitored is attractive. This force is transferred axially to the FBG producing a variation in the reflected wavelength.
  • the value of wavelength variation can be related to the magnetic force between the material and the sensor through a calibration curve ( Figure 3).
  • the magnetic force between the magnet and ferromagnetic material varies as a function of distance. This variation allows the use of this sensor in many situations, such as monitoring, with or without contact, the integrity of metallic structures, preferably made or containing ferromagnetic steel.
  • One possible application is monitoring, but not limited to, deformations, displacements, vibrations and corrosion in towers, structures and equipment used in the generation and transmission of electricity and in the oil and gas industry.
  • a set of sensors can be employed simultaneously for imaging corrosion areas commonly found in pipelines and equipment used in the oil and gas industry ( Figures 4 and 5 and Annexes 3 and 4).
  • One of the advantages of this sensor is that it does not require prior instrumentation of the structure to be monitored.
  • the maximum variation in wavelength of the magnetic force sensor to the Bragg network obtained using an example of a magnet with a 3.0 mm external diameter and 5.0 mm long is 3 nm for a distance of 50 m between the sensor and a ferromagnetic plate. In this distance, The value of the force acting on the sensor is approximately 2.0N. Its estimated wavelength sensitivity is 10 pm, which corresponds to a force of 20 mN. The useful distance range for sensor use is 5.0 mm. The present invention also provides the use of arrays of these sensors as illustrated in Annex 5.
  • the magnet used in the sensor of the present invention generates a magnetic field in the equipment / frame, which will generate another magnetic field in response to it, creating in the region between the sensor and the equipment / frame a field gradient.
  • This causes the magnet bonded to the fiber to be attracted to the equipment or structure, thus tensioning the fiber and Bragg mesh, changing the wavelength reflected by it. Since the field gradient depends on the distance between the magnet and the equipment or structure, a mapping using the sensor or the use of a sensor array can generate an image of the surface of the equipment or structure. Therefore, it can be said that the sensor of the present invention is an active sensor as it generates the magnetic field and measures the response of this field in the ferromagnetic material.
  • Another object of the invention is a FBG sensor manufacturing process. Said process comprises the steps of:
  • the optical fiber containing a Bragg mesh is fixed to the inside of the magnet with glue or general purpose adhesives, preferably for adhesion of metallic substrates, preferably cyanoacrylates, primarily Loctite 496.
  • the encapsulation medium is made of non-metallic material. magnetic, preferably acrylic, teflon, glass or resin, with a central guide that allows the magnet to move inside.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Optical Transform (AREA)

Abstract

The present invention provides a magnetic force sensor based on optical fiber Bragg gratings (FBG), and also describes the method for manufacturing same and the use thereof. The invention is advantageously used for monitoring the position, displacement, vibration and deformation of iron or steel structures, and also for monitoring corrosion in towers, structures and equipment used to generate and transmit electric energy, and in the oil and gas industries.

Description

Relatório Descritivo de Patente de Invenção  Patent Invention Descriptive Report
Sensor de Força Magnética à Fibra Óptica, Processo de Fabricação e Uso do Mesmo Campo da Invenção  Fiber Optic Magnetic Force Sensor, Manufacturing Process and Same Field of Invention
A invenção pertence ao campo da engenharia eletrônica e de materiais. Mais especificamente, a invenção descreve um sensor de força magnética baseado em fibras óticas com redes de Bragg (FBG), sendo também descrito o processo de fabricação do mesmo e seu uso. A invenção é vantajosamente aplicada ao monitoramento da posição, deslocamento, vibração e deformação de estruturas feitas de ferro/aço, e também para monitorar corrosão em torres, estruturas e equipamentos utilizados na geração e transmissão de energia elétrica e na indústria de petróleo e gás. Antecedentes da Invenção  The invention belongs to the field of electronic and materials engineering. More specifically, the invention describes a Bragg Grating Optical Fiber (FBG) -based magnetic force sensor, as well as its manufacturing process and its use. The invention is advantageously applied for monitoring the position, displacement, vibration and deformation of structures made of iron / steel, and also for monitoring corrosion in towers, structures and equipment used in the generation and transmission of electricity and in the oil and gas industry. Background of the Invention
O documento US 5,680,489 descreve um sistema ótico para detecção de sinais provenientes de muitos sensores FBG e de alguns detectores. A presente invenção difere do referido documento, entre outros motivos técnicos, por descrever um sensor que usa um ímã permanente colado na fibra óptica, ao invés de usar uma multi-camada de materiais magnetostrictivos.  US 5,680,489 describes an optical system for detecting signals from many FBG sensors and some detectors. The present invention differs from said document, among other technical reasons, in that it describes a sensor using a permanent magnet bonded to the optical fiber, rather than using a multi-layer magnetostrictive material.
O documento WO 2010/009340 descreve sensores com contato físico com a estrutura a ser monitorada. A presente invenção difere do referido documento, entre outros motivos técnicos, por não requerer contato físico com a estrutura a ser monitorada.  WO 2010/009340 describes sensors with physical contact with the structure to be monitored. The present invention differs from said document, among other technical reasons, in that it does not require physical contact with the structure to be monitored.
O documento US 7,406,218 difere da presente invenção, dentre outros motivos técnicos, por estar relacionado ao sistema ótico de detecção, enquanto a presente invenção tem relação com o transdutor. Além disso, a presente invenção proporciona o uso de qualquer sistema ótico para detectar as variações do comprimento de onda da rede de Bragg.  US 7,406,218 differs from the present invention, among other technical reasons, in that it relates to the optical detection system, while the present invention relates to the transducer. In addition, the present invention provides the use of any optical system to detect Bragg network wavelength variations.
A literatura patentária identificada não antecipa, ou sequer sugere, os ensinamentos da presente invenção. Sumário da Invenção The identified patent literature does not anticipate, or even suggest, the teachings of the present invention. Summary of the Invention
A presente invenção proporciona um sensor de força magnética, seu processo de obtenção e seu uso. Os sensores da invenção são melhorados quando comparamos aos sensores convencionais, onde o resultado da transdução é uma voltagem elétrica.  The present invention provides a magnetic force sensor, its obtaining process and its use. The sensors of the invention are improved compared to conventional sensors, where the result of transduction is an electrical voltage.
É um dos objetos da invenção um sensor de elevada imunidade à interferência eletromagnética.  It is one of the objects of the invention a sensor with high immunity to electromagnetic interference.
É outro dos objetos da invenção um sensor com menor sensibilidade à falha de conexões.  Another object of the invention is a sensor with lower sensitivity to connection failure.
É outro dos objetos da invenção um sensor de baixo peso, pequenas dimensões e baixo custo.  Another object of the invention is a low weight, small size and low cost sensor.
É outro dos objetos da invenção um sensor que proporciona multiplexação.  Another object of the invention is a sensor that provides multiplexing.
É outro dos objetos da invenção um sensor que proporciona sensoriamento remoto sem a necessidade de baterias no local de realização das medições.  Another object of the invention is a sensor that provides remote sensing without the need for batteries at the measurement site.
Em uma concretização preferencial, a presente invenção proporciona um novo tipo de sensor FBG. Em uma concretização preferencial, o sensor compreende: i) pelo menos um ímã; e ii) pelo menos uma fibra óptica contendo uma rede de Bragg.  In a preferred embodiment, the present invention provides a new type of FBG sensor. In a preferred embodiment, the sensor comprises: i) at least one magnet; and ii) at least one optical fiber containing a Bragg network.
Em uma concretização preferencial, o sensor adicionalmente compreende: iii) um meio de encapsulamento feito de material não magnético.  In a preferred embodiment, the sensor further comprises: iii) an encapsulation means made of non-magnetic material.
Em uma concretização preferencial, o ímã do referido sensor é cilíndrico. Em uma concretização preferencial, o ímã do referido sensor contém ferro em sua composição. Em uma concretização preferencial, o ímã do referido sensor é de um material contendo Nd. Em uma concretização preferencial, o ímã do referido sensor é de um material contendo B. Em uma concretização preferencial, o ímã do referido sensor é de NdFeB. Em uma concretização preferencial, o ímã do referido sensor contém Sm. Em uma concretização preferencial, o ímã do referido sensor é de um material contendo Co. Em uma concretização preferencial, o ímã do referido sensor é de SmCo. In a preferred embodiment, the magnet of said sensor is cylindrical. In a preferred embodiment, the magnet of said sensor contains iron in its composition. In a preferred embodiment, the magnet of said sensor is of a material containing Nd. In a preferred embodiment, the magnet of said sensor is of a B-containing material. In a preferred embodiment, the magnet of said sensor is of NdFeB. In a preferred embodiment, the magnet of said sensor contains Sm. Preferred embodiment, the magnet of said sensor is of a Co-containing material. In a preferred embodiment, the magnet of said sensor is of SmCo.
Em uma concretização preferencial o referido ímã é dotado de pelo menos um furo passante.  In a preferred embodiment said magnet is provided with at least one through hole.
Em uma concretização preferida, a presente invenção consiste em um novo tipo de sensor ótico-magnético interrogado por uma FBG. O sensor preferencialmente compreende: i) ímã cilíndrico de NdFeB com um furo passante central; ii) fibra óptica contendo uma rede de Bragg fixada na parte interna do ímã com cola; iii) encapsulamento confeccionado de material não magnético com uma guia central que permite o deslocamento do ímã no seu interior.  In a preferred embodiment, the present invention consists of a new type of optical-magnetic sensor interrogated by an FBG. The sensor preferably comprises: i) NdFeB cylindrical magnet with a central through hole; ii) optical fiber containing a Bragg mesh fixed to the inside of the magnet with glue; iii) non-magnetic encapsulation made with a central guide that allows the magnet to move inside.
É um outro objeto da invenção um processo de fabricação de sensores FBG. Referido processo compreende as etapas de:  Another object of the invention is a process for manufacturing FBG sensors. Said process comprises the steps of:
i) aderir pelo menos um ímã sobre pelo menos uma fibra óptica contendo uma rede de Bragg; e  (i) adhere at least one magnet to at least one optical fiber containing a Bragg mesh; and
ii) encapsular o material do item i) com material não magnético.  ii) encapsulate the material of item i) with non-magnetic material.
É um outro objeto da invenção o uso de um sensor magnético-ótico compreendendo: i) pelo menos um ímã; e ii) pelo menos uma fibra óptica contendo uma rede de Bragg, para produção de um sistema de monitoramento de posição, deformação, deslocamento, vibração e/ou corrosão de estruturas metálicas. Em uma concretização preferencial, a invenção é vantajosamente aplicada ao monitoramento da posição, deslocamento, vibração e deformação de estruturas feitas de ferro/aço, e também para monitorar corrosão em torres, estruturas e equipamentos utilizados na geração e transmissão de energia elétrica e na indústria de petróleo e gás.  It is another object of the invention to use a magnetic-optical sensor comprising: i) at least one magnet; and ii) at least one optical fiber containing a Bragg network for producing a position monitoring, deformation, displacement, vibration and / or corrosion monitoring system for metal structures. In a preferred embodiment, the invention is advantageously applied for monitoring the position, displacement, vibration and deformation of structures made of iron / steel, as well as for monitoring corrosion in towers, structures and equipment used in power generation and transmission and in industry. of oil and gas.
Estes e outros objetos da invenção serão melhor compreendidos a partir da descrição detalhada a seguir.  These and other objects of the invention will be better understood from the following detailed description.
Breve Descrição das Figuras Brief Description of the Figures
A figura 1 mostra um desenho esquemático de uma concretização preferencial de um sensor de força magnética à fibra ótica, onde (a) significa fibra ótica, (b) significa fixação da fibra, (c) significa encapsulamento, (d) significa rede de Bragg, (e) significa guia, e (f) significa micro-ímã. Figure 1 shows a schematic drawing of a preferred embodiment of a magnetic force sensor to the optical fiber, where (a) means optical fiber, (b) means fiber fixation, (c) means encapsulation, (d) means Bragg network, (e) means guide, and (f) means micro magnet.
A figura 2 mostra as respostas de uma concretização preferencial de sensor para 3 diferentes forças magnéticas, onde (a) significa potência em dBm, e (b) significa Comprimento de onda em nm.  Figure 2 shows the responses of a preferred sensor embodiment for 3 different magnetic forces, where (a) means power in dBm, and (b) means wavelength in nm.
A figura 3 mostra a curva de calibração da variação de comprimento de onda VS. Força magnética, onde (a) significa medido, (b) significa ajuste, e (c) significa força em Newton.  Figure 3 shows the calibration curve of the VS wavelength range. Magnetic force, where (a) means measured, (b) means fit, and (c) means force in Newton.
A figura 4 mostra a imagem obtida com o sensor varrendo a área sobre o pit de corrosão.  Figure 4 shows the image obtained with the sensor scanning the area over the corrosion pit.
A figura 5 mostra a imagem obtida com o sensor varrendo a área sobre o pit de corrosão natural.  Figure 5 shows the image obtained with the sensor scanning the area over the natural corrosion pit.
Breve Descrição dos Anexos Brief Description of Attachments
O anexo 1 mostra a foto de uma concretização preferencial de sensor. Annex 1 shows the photo of a preferred sensor embodiment.
O anexo 2 mostra a foto de uma concretização preferencial de sensor e cabo de fibra ótica. Annex 2 shows a photo of a preferred embodiment of sensor and fiber optic cable.
O anexo 3 mostra a foto de um pit de corrosão fabricado em uma chapa de aço 1020.  Annex 3 shows a picture of a corrosion pit made of a 1020 sheet steel.
O anexo 4 mostra a foto de um pit de corrosão natural em uma chapa de aço utilizada em tanques de armazenamento de petróleo.  Annex 4 shows a picture of a naturally corrosion pit in a steel plate used in oil storage tanks.
O anexo 5 mostra a foto de uma concretização preferencial da invenção, de um array FBG contendo 4 sensores. Descrição Detalhada da Invenção  Annex 5 shows a photo of a preferred embodiment of the invention of an FBG array containing 4 sensors. Detailed Description of the Invention
A presente invenção proporciona um sensor de força magnética, seu processo de obtenção e seu uso. Em uma concretização preferencial, o sensor compreende: i) pelo menos um ímã; e ii) pelo menos uma fibra óptica contendo uma rede de Bragg. O conceito inventivo comum aos diversos objetos da invenção consiste na combinação de um elemento magnético a uma fibra ótica contendo uma rede de Bragg. Sensores baseados em fibras óticas com redes de Bragg (FBG) podem ser utilizados diretamente para medir grandezas como tensão, deformação, temperatura e pressão. Com a utilização de sensores apropriados, outras grandezas físicas podem ser mensuradas, como campo magnético, corrente elétrica, posição etc. Nos sensores FBG, a transdução da grandeza a ser medida é feita em comprimento de onda. Isto traz inúmeras vantagens quando comparamos estes sensores com sensores convencionais onde o resultado da transdução é uma voltagem elétrica. Dentre estas vantagens, podemos citar a imunidade à interferência eletromagnética, menor sensibilidade à falha de conexões, baixo peso e pequenas dimensões, baixo custo, facilidade de multiplexação, além de permitir o sensoriamento remoto sem a necessidade de baterias no local de realização das medições. The present invention provides a magnetic force sensor, its obtaining process and its use. In a preferred embodiment, the sensor comprises: i) at least one magnet; and ii) at least one optical fiber containing a Bragg network. The inventive concept common to the various objects of the invention is the combination of a magnetic element with an optical fiber containing a Bragg network. Fiber-based sensors with Bragg networks (FBG) can be used directly to measure quantities such as stress, strain, temperature and pressure. Using appropriate sensors, other physical quantities can be measured, such as magnetic field, electric current, position, etc. In FBG sensors, the transduction of the quantity to be measured is done in wavelength. This has numerous advantages when comparing these sensors with conventional sensors where the transduction result is an electrical voltage. These advantages include immunity to electromagnetic interference, lower sensitivity to connection failure, low weight and small size, low cost, ease of multiplexing, as well as remote sensing without the need for batteries at the measurement site.
A presente invenção proporciona um novo tipo de sensor de força magnética interrogado por uma FBG. Em uma concretização preferencial, o sensor compreende: i) ímã cilíndrico de NdFeB com um furo passante central com diâmetro de 0,5 mm, diâmetro externo que pode variar de 1 ,0 a 10,0 mm e comprimento que pode variar de 1 ,0 até 10 mm, dependendo da sensibilidade e resolução desejadas; ii) fibra óptica contendo uma rede de Bragg fixada na parte interna do ímã com cola ou adesivos de uso geral, preferencialmente para adesão de substratos metálicos, preferivelmente cianoacrilatos, prioritariamente Loctite 496; iii) encapsulamento confeccionado de material não magnético, preferencialmente acrílico, teflon, vidro ou resina, com uma guia central que permite o deslocamento do ímã no seu interior. Em uma concretização preferencial ilustrada na figura 1 e nos anexos 2 e 3, a parte da fibra óptica acima da rede de Bragg é fixada com cola na extremidade superior do encapsulamento. Basta que o conjunto esteja a alguns milímetros de qualquer estrutura ferromagnética, ou em uma região de gradiente de campo magnético, para que o sensor produza uma resposta (Figura 2).  The present invention provides a new type of magnetic force sensor interrogated by an FBG. In a preferred embodiment, the sensor comprises: i) NdFeB cylindrical magnet with a central through hole with a diameter of 0.5 mm, an outside diameter ranging from 1.0 to 10.0 mm and a length ranging from 1, 0 to 10 mm, depending on desired sensitivity and resolution; ii) optical fiber containing a Bragg mesh fixed to the inside of the magnet with glue or general purpose adhesives, preferably for adhesion of metal substrates, preferably cyanoacrylates, primarily Loctite 496; iii) encapsulation made of non-magnetic material, preferably acrylic, Teflon, glass or resin, with a central guide that allows the magnet to move inside. In a preferred embodiment illustrated in Figure 1 and Annexes 2 and 3, the part of the optical fiber above the Bragg mesh is glued to the upper end of the package. It is enough that the array is within millimeters of any ferromagnetic structure, or in a magnetic field gradient region, for the sensor to produce a response (Figure 2).
Em uma concretização preferencial, o ímã do referido sensor contém ferro em sua composição. Em uma concretização preferencial, o ímã do referido sensor é de um material contendo Nd. Em uma concretização preferencial, o ímã do referido sensor é de um material contendo B. Em uma concretização preferencial, o ímã do referido sensor é de NdFeB. Em uma concretização preferencial, o ímã do referido sensor contém Sm. Em uma concretização preferencial, o ímã do referido sensor é de um material contendo Co. Em uma concretização preferencial, o ímã do referido sensor é de SmCo. In a preferred embodiment, the magnet of said sensor contains iron in its composition. In a preferred embodiment, the magnet of said sensor is of a material containing Nd. In one embodiment Preferably, the magnet of said sensor is of a B-containing material. In one preferred embodiment, the magnet of said sensor is of NdFeB. In a preferred embodiment, the magnet of said sensor contains Sm. In a preferred embodiment, the magnet of said sensor is of a Co-containing material. In a preferred embodiment, the magnet of said sensor is of SmCo.
A força magnética originada pela interação entre o ímã e a estrutura ferromagnética ou fonte de campo a ser monitorada é atrativa. Esta força é transferida de forma axial para a FBG produzindo uma variação no comprimento de onda refletido. O valor da variação do comprimento de onda pode ser relacionado à força magnética entre o material e o sensor através de uma curva de calibração (Figura 3).  The magnetic force arising from the interaction between the magnet and the ferromagnetic structure or field source to be monitored is attractive. This force is transferred axially to the FBG producing a variation in the reflected wavelength. The value of wavelength variation can be related to the magnetic force between the material and the sensor through a calibration curve (Figure 3).
Uso do sensor Sensor Usage
A força magnética entre o ímã e material ferromagnético varia em função da distância. Esta variação permite a utilização deste sensor em inúmeras situações como, por exemplo, no monitoramento, com ou sem contato, da integridade de estruturas metálicas, preferencialmente que sejam feitas ou que contenham aço ferromagnético. Uma aplicação possível é o monitoramento de, mas não se limitando a, deformações, deslocamentos, vibrações e corrosão em torres, estruturas e equipamentos utilizados na geração e transmissão de energia elétrica e na indústria de petróleo e gás. Utilizando a facilidade de multiplexação dos sensores FBG, um conjunto de sensores pode ser empregado simultaneamente para obtenção de imagens de áreas de corrosão comumente encontradas em dutos e equipamentos utilizados na indústria de petróleo e gás (Figuras 4 e 5 e Anexos 3 e 4). Uma das vantagens deste sensor é o fato de não requerer a instrumentação prévia da estrutura a ser monitorada.  The magnetic force between the magnet and ferromagnetic material varies as a function of distance. This variation allows the use of this sensor in many situations, such as monitoring, with or without contact, the integrity of metallic structures, preferably made or containing ferromagnetic steel. One possible application is monitoring, but not limited to, deformations, displacements, vibrations and corrosion in towers, structures and equipment used in the generation and transmission of electricity and in the oil and gas industry. Using the ease of multiplexing FBG sensors, a set of sensors can be employed simultaneously for imaging corrosion areas commonly found in pipelines and equipment used in the oil and gas industry (Figures 4 and 5 and Annexes 3 and 4). One of the advantages of this sensor is that it does not require prior instrumentation of the structure to be monitored.
Exemplos Examples
A máxima variação no comprimento de onda do sensor de força magnética à rede de Bragg obtida, com a utilização de um exemplo de ímã com 3,0 mm de diâmetro externo e 5,0 mm de comprimento é de 3 nm, para uma distância de 50 m entre o sensor e uma placa ferromagnética. Nesta distância, o valor da força que atua no sensor é de aproximadamente 2,0N. Sua sensibilidade estimada em comprimento de onda é de 10 pm, que corresponde a uma força de 20 mN. A faixa de distância útil para utilização do sensor é de 5,0 mm. A presente invenção proporciona também o uso de arrays destes sensores, como ilustrado no Anexo 5. The maximum variation in wavelength of the magnetic force sensor to the Bragg network obtained using an example of a magnet with a 3.0 mm external diameter and 5.0 mm long is 3 nm for a distance of 50 m between the sensor and a ferromagnetic plate. In this distance, The value of the force acting on the sensor is approximately 2.0N. Its estimated wavelength sensitivity is 10 pm, which corresponds to a force of 20 mN. The useful distance range for sensor use is 5.0 mm. The present invention also provides the use of arrays of these sensors as illustrated in Annex 5.
O ímã usado no sensor da presente invenção gera um campo magnético no equipamento/estrutura, que vai gerar outro campo magnético em resposta a este, criando na região entre o sensor e o equipamento/estrutura um gradiente de campo. Isto faz que o ímã colado na fibra seja atraído pelo equipamento ou estrutura, portanto, tensionando a fibra e a rede de Bragg, alterando o comprimento de onda refletido por ela. Como o gradiente de campo depende da distância entre o ímã e o equipamento ou estrutura um mapeamento utilizando o sensor ou a utilização de uma matriz de sensores pode gerar uma imagem da superfície do equipamento ou estrutura. Portanto, pode-se dizer que o sensor da presente invenção é um sensor ativo, pois ele gera o campo magnético e mede a resposta deste campo no material ferromagnético.  The magnet used in the sensor of the present invention generates a magnetic field in the equipment / frame, which will generate another magnetic field in response to it, creating in the region between the sensor and the equipment / frame a field gradient. This causes the magnet bonded to the fiber to be attracted to the equipment or structure, thus tensioning the fiber and Bragg mesh, changing the wavelength reflected by it. Since the field gradient depends on the distance between the magnet and the equipment or structure, a mapping using the sensor or the use of a sensor array can generate an image of the surface of the equipment or structure. Therefore, it can be said that the sensor of the present invention is an active sensor as it generates the magnetic field and measures the response of this field in the ferromagnetic material.
Processo Process
É outro objeto da invenção um processo de fabricação de sensores FBG. Referido processo compreende as etapas de:  Another object of the invention is a FBG sensor manufacturing process. Said process comprises the steps of:
i. aderir um ímã sobre) uma fibra óptica contendo uma rede de Bragg; e ii. encapsular o material do item i) com material não magnético.  i. adhere a magnet to) an optical fiber containing a Bragg network; and ii. encapsulate the material of item (i) with non-magnetic material.
Preferencialmente, a fibra óptica contendo uma rede de Bragg é fixada na parte interna do ímã com cola ou adesivos de uso geral, preferencialmente para adesão de substratos metálicos, preferivelmente cianoacrilatos, prioritariamente Loctite 496. Preferencialmente, o meio de encapsulamento é confeccionado de material não magnético, preferencialmente acrílico, teflon, vidro ou resina, com uma guia central que permite o deslocamento do ímã no seu interior.  Preferably, the optical fiber containing a Bragg mesh is fixed to the inside of the magnet with glue or general purpose adhesives, preferably for adhesion of metallic substrates, preferably cyanoacrylates, primarily Loctite 496. Preferably, the encapsulation medium is made of non-metallic material. magnetic, preferably acrylic, teflon, glass or resin, with a central guide that allows the magnet to move inside.
Os versados na técnica imediatamente valorizarão os ensinamentos da presente invenção, e entenderão que variações nas formas de concretizar a invenção em relação aos exemplos ora ilustrados devem ser consideradas como dentro do escopo da invenção e das reivindicações anexas. Those skilled in the art will immediately appreciate the teachings of the present invention, and will understand that variations in the embodiments of invention in relation to the examples illustrated herein should be considered as falling within the scope of the invention and the appended claims.

Claims

Reivindicações Sensor de Força Magnética à Fibra Óptica, Processo de Fabricação e Uso do Mesmo Fiber Optic Magnetic Force Sensor, Manufacturing Process and Use
1. Sensor ótico-magnético interrogado por uma FBG, caracterizado por compreender: i) pelo menos um ímã; e ii) pelo menos uma fibra óptica contendo uma rede de Bragg. Optical-magnetic sensor interrogated by an FBG, characterized in that it comprises: (i) at least one magnet; and ii) at least one optical fiber containing a Bragg network.
2. Sensor de acordo com a reivindicação 1 , caracterizado por adicionalmente compreender um meio de encapsulamento feito de material não magnético.  Sensor according to claim 1, characterized in that it further comprises an encapsulation means made of non-magnetic material.
3. Sensor de acordo com a reivindicação 1 ou 2, caracterizado pelo ímã ser cilíndrico.  Sensor according to claim 1 or 2, characterized in that the magnet is cylindrical.
4. Sensor de acordo com a reivindicação 1 , 2 ou 3, caracterizado pelo ímã ser dotado de pelo menos um furo passante.  Sensor according to Claim 1, 2 or 3, characterized in that the magnet is provided with at least one through hole.
5. Sensor de acordo com qualquer uma das reivindicações 1-4, caracterizado pelo ímã ser feito de um material selecionado do grupo que compreende materiais contendo: ferro; Nd; B; Sm; Co; ou combinações dos mesmos.  Sensor according to any one of claims 1-4, characterized in that the magnet is made of a material selected from the group comprising materials containing: iron; Nd; B; Sm; Co; or combinations thereof.
6. Sensor de acordo com a reivindicação 5, caracterizado pelo ímã ser feito de um material contendo NdFeB.  Sensor according to claim 5, characterized in that the magnet is made of a material containing NdFeB.
7. Sensor de acordo com a reivindicação 5, caracterizado pelo ímã ser feito de um material contendo SmCo.  Sensor according to Claim 5, characterized in that the magnet is made of a SmCo-containing material.
8. Sensor de acordo com qualquer uma das reivindicações 2-7, caracterizado pelo meio de encapsulamento compreender material não magnético com uma guia central para o deslocamento do ímã no seu interior.  Sensor according to any one of claims 2-7, characterized in that the encapsulation means comprises non-magnetic material with a central guide for the displacement of the magnet within it.
9. Sensor de acordo com qualquer uma das reivindicações 4-8, caracterizado pelo furo passante ser central.  Sensor according to any one of claims 4-8, characterized in that the through hole is central.
10. Sensor de acordo com a reivindicação 9, caracterizado pelo furo passante possuir diâmetro de 0,5 mm, diâmetro externo de 1 ,0 a 10,0 mm e comprimento de 1 ,0 a 10 mm. Sensor according to Claim 9, characterized in that the through hole has a diameter of 0.5 mm, an external diameter of 1.0 to 10.0 mm and a length of 1.0 to 10 mm.
11. Processo de fabricação de sensores FBG, caracterizado por compreender as etapas de: 11. FBG sensor manufacturing process, characterized by comprising the steps of:
i) aderir pelo menos um ímã sobre pelo menos uma fibra óptica contendo uma rede de Bragg; e  (i) adhere at least one magnet to at least one optical fiber containing a Bragg mesh; and
ii) encapsular o material do item i) com material não magnético.  ii) encapsulate the material of item i) with non-magnetic material.
12. Uso de um sensor magnético-ótico contendo: i) pelo menos um ímã; e ii) pelo menos uma fibra óptica contendo uma rede de Bragg, caracterizado por ser para a produção de um sistema de monitoramento de posição, deformação, deslocamento, vibração e/ou corrosão de estruturas metálicas.  12. Use of a magnetic-optical sensor containing: (i) at least one magnet; and ii) at least one optical fiber containing a Bragg network, characterized in that it is for the production of a position monitoring system, deformation, displacement, vibration and / or corrosion of metallic structures.
PCT/BR2012/000086 2011-04-01 2012-03-29 Fiber optic magnetic force sensor, method for manufacturing same and use thereof WO2012129625A2 (en)

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