CN112525237A - EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging and measuring method - Google Patents
EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging and measuring method Download PDFInfo
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- CN112525237A CN112525237A CN201910877204.6A CN201910877204A CN112525237A CN 112525237 A CN112525237 A CN 112525237A CN 201910877204 A CN201910877204 A CN 201910877204A CN 112525237 A CN112525237 A CN 112525237A
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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
-
- 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
- G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
- G01D11/24—Housings ; Casings for instruments
- G01D11/245—Housings for sensors
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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
- G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
- G01D11/24—Housings ; Casings for instruments
- G01D11/26—Windows; Cover glasses; Sealings therefor
-
- 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
- G01D5/35312—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 Fabry Perot
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- Measuring Temperature Or Quantity Of Heat (AREA)
- Measuring Fluid Pressure (AREA)
- Optical Transform (AREA)
Abstract
The invention discloses an EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging and a measuring method. The incident bare fiber and the reflection bare fiber are inserted into the glass tube, and the two end faces of the optical fiber form an optical fiber F-P cavity. The manufactured EFPI structure is packaged in the cylindrical epoxy resin to form the pressure elastic body. The fiber bragg grating which is positioned outside the glass tube and in a free state is packaged in the thin copper tube, one part of the thin copper tube is packaged in the epoxy resin, and the other part of the thin copper tube is packaged in the sealant. Under the action of pressure, the epoxy resin is compressed under stress, the glass tube packaged in the epoxy resin is compressed axially along with the deformation of the epoxy resin, and the length of an F-P cavity in the EFPI structure is shortened along with the shortening of the axial length of the glass tube. The EFPI-FBG composite pressure and temperature sensor can be used for detecting the pressure and the temperature of hydraulic oil in a hydraulic pipeline.
Description
Technical Field
The invention belongs to the technical field of pressure sensor preparation, and particularly relates to an EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging and a measuring method.
Background
Pressure sensors are widely used in industrial production. Compared with the traditional electrical pressure sensors such as the traditional resistance strain gauge pressure sensor and the semiconductor strain gauge pressure sensor, the pressure sensor is not suitable for the environment which requires insulation and strong electromagnetic interference. The optical fiber sensor has the characteristics of high precision, small volume, high temperature resistance, corrosion resistance, strong electromagnetic interference resistance, good electrical insulation, small propagation loss and the like, and can be applied to severe environments and remote measurement and monitoring.
In the structural form of a common optical fiber Fabry-Perot pressure sensor, the MEMS optical fiber Fabry-Perot pressure sensor realizes pressure signal sensing by changing the cavity length due to the deformation of a silicon sensitive film caused by external pressure, and has the advantages of small volume, high pressure sensitivity, small pressure measurement range, complex bonding technology between the silicon film and a base, high operation requirement, poor sealing performance in a high-pressure environment and inapplicability to high-pressure oil pressure detection in a hydraulic pipeline. In addition, the EFPI type Fabry-Perot pressure sensor has the advantages that the glass tube is directly subjected to pressure action, the axial length is extended, and the cavity length of the F-P cavity is further changed. The measuring range is wide, but the pressure sensitivity is low, and the glass tube is directly exposed in a pressure environment and is impacted by the outside, so that the sensor is easily damaged.
Disclosure of Invention
The invention aims to solve the technical problem of providing an EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation and a measuring method thereof. The EFPI-FBG composite pressure and temperature sensor can be used for detecting the pressure and the temperature of hydraulic oil in a hydraulic pipeline.
The technical scheme adopted by the invention for solving the technical problems is as follows: firstly, providing an EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation, wherein a sensing head of the sensor comprises an incident bare fiber, a reflection bare fiber, a glass tube, a copper tube, a metal shell and an end cover; one part of the incident bare fiber and one part of the reflection bare fiber are inserted into the glass tube, the other part of the incident bare fiber and the reflection bare fiber are positioned outside the glass tube, and an optical fiber F-P cavity is formed between the end surfaces of the two optical fibers in the glass tube; the incident bare fiber and the reflecting bare fiber are respectively fixed with the inner wall of the glass tube, the optical fiber in the glass tube is in a free state, the incident optical fiber is engraved with a grating and is positioned outside the glass tube, the optical fiber grating is packaged in the copper tube, and two ends of the optical fiber grating are fixed with two ends of the copper tube.
According to the technical scheme, the fixed length of the incident bare fiber, the reflecting bare fiber and the inner wall of the glass tube is 2-3 mm.
According to the technical scheme, the glass tube is completely wrapped by the epoxy resin, and the distance allowance exists between the end face of the epoxy resin and the end face of the glass tube.
According to the technical scheme, a layer of lubricating grease is coated between the epoxy resin and the inner wall of the metal shell. In the process that the tail end of the epoxy resin elastomer is deformed under the action of pressure, the friction between the resin and the inner wall of the shell is reduced, and the sensitivity of pressure sensing is improved.
According to the technical scheme, the top of the cured epoxy resin is sealed by using the sealant, and the thickness of the sealant is more than 10 mm.
According to the technical scheme, one end of the metal shell is provided with an outer taper pipe thread which is connected with a hydraulic pipeline; the other end of the metal shell is connected with the end cover through threads.
According to the technical scheme, the glass tube is completely packaged in the cylindrical epoxy resin, and the glass tube is positioned in the center of the epoxy resin to form the pressure elastic body.
According to the technical scheme, the glass tube is a quartz glass tube.
The invention also provides a measuring method of the EFPI-FBG composite pressure temperature sensor, which comprises the following steps that firstly, the incident bare fiber and the reflection bare fiber which are engraved with the grating are respectively inserted into a glass tube from two ends, an F-P cavity is formed on two end faces, and the optical fibers are fixed by glue at two ends of the glass tube; step two, packaging the optical grating outside the glass tube in the copper tube, enabling the optical grating to be in a free bending state, and fixing the optical fiber and the two ends of the copper tube by using glue; completely packaging the glass tube in cylindrical epoxy resin, wherein the glass tube is positioned in the center of the epoxy resin to form a pressure elastomer, and meanwhile, a part of the copper tube is embedded in the epoxy resin; coating solid lubricating grease on the inner wall of the metal shell, wherein the coating length is consistent with that of the pressure elastomer, and the packaged pressure elastomer is sleeved in the metal shell; adding sealant to the top of the metal shell, and completely embedding the other part of the copper pipe into the sealant; one part of the optical fiber jumper is embedded into the sealant; step six, the left end part of the metal shell is connected with the end cover through threads; and step seven, connecting the manufactured EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging into a hydraulic pipeline through a taper pipe external thread, and connecting a jumper into the FP-FBG composite demodulator.
According to the technical scheme, the Fabry-Perot cavity length variation delta l is measured by utilizing the FP-FBG composite demodulator1And the fiber grating wavelength drift amount delta lambda; the temperature change delta T is obtained through the wavelength drift delta lambda of the fiber bragg grating, so that the cavity length change delta l of the Fabry-Perot cavity caused by the temperature change of the sensor is obtained2(ii) a Fabry-Perot cavity length change delta l-delta l caused by hydraulic oil pressure in hydraulic pipeline1±Δl2And further obtaining the hydraulic oil pressure in the hydraulic pipeline.
The invention has the following beneficial effects: when the glass tube packaged in the epoxy resin is subjected to pressure and temperature, the axial strain of the glass tube is in direct proportion to the pressure and temperature changes respectively. Namely, the length change of the F-P cavity in the EFPI structure is respectively in direct proportion to the pressure change and the temperature change. And the pressure and the temperature influence the cavity length of the Fabry-Perot cavity independently. The temperature change is judged by utilizing the wavelength drift amount of the fiber bragg grating, so that the cavity length change of the F-P cavity influenced by the temperature is obtained, and the cavity length change caused by the temperature change when the pressure of the sensor acts is further compensated.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic structural diagram of an EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an EFPI-FBG composite sensor before being packaged in an embodiment of the present invention;
FIG. 3 is a graph of pressure analysis of an end face of an EFPI-FBG composite pressure temperature sensor based on epoxy encapsulation.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The first embodiment is as follows: as shown in fig. 1, the sensing head of the sensor includes an incident bare fiber, a reflective bare fiber, an FBG (fiber bragg grating), a quartz glass tube, epoxy resin, sealant, a copper tube, a stainless steel metal shell and an end cap; one part of the incident bare fiber and the reflection bare fiber is inserted into the quartz glass tube, and the other part of the incident bare fiber and the reflection bare fiber is arranged outside the glass tube. An F-P cavity is formed between the end faces of the two optical fibers in the glass tube. The bare optical fiber and the inner wall of the glass tube are fixed by strong glue at two ends of the glass tube, and the fixed length is 2-3 mm. The optical fiber in the glass tube is in a free state. The incident optical fiber is engraved with a grating 12 outside the glass tube, the fiber grating is packaged in the copper tube, the fiber grating is in a completely relaxed state of bending, and two ends of the grating and two ends of the copper tube are fixed by AB glue. In burying the EFPI structure in epoxy, epoxy should wrap up the glass pipe completely, and there should be certain distance surplus in resin terminal surface and the glass pipe terminal surface, when receiving pressure or impact, can effectively protect the Fabry-Perot cavity structure. The EFPI structure is packaged in the center of the cylindrical epoxy resin to form a pressure elastic body; a certain distance exists between the copper tube and the glass tube. A small part of the copper pipe is positioned in the epoxy resin, and a large part of the copper pipe is embedded in the sealant. And a layer of lubricating grease is coated between the epoxy resin and the inner wall of the metal shell. In the process that the tail end of the epoxy resin elastomer is deformed under the action of pressure, the friction between the resin and the inner wall of the shell is reduced, and the sensitivity of pressure sensing is improved. And sealing the top of the cured epoxy resin by using a sealant. The thickness of the sealant is larger than 10mm, and the sensor can be effectively sealed after being connected to a hydraulic pipeline. The left end part of the metal shell is connected with the end cover through threads, so that objects in the metal shell are prevented from being extruded out under the action of high pressure, and the pressure sensitivity enhancing effect can be achieved. The right end part of the metal shell is provided with an outer taper pipe thread which can be connected with a hydraulic pipeline.
Example two: in the EFPI-FBG composite pressure and temperature sensor structure based on epoxy resin encapsulation, the outer diameters of an incident bare fiber 1 and a reflection bare fiber 8 are 125 micrometers, the two fibers are respectively inserted into a quartz glass tube 9 with the inner diameter of 130 micrometers and the outer diameter of 1mm, and air cavities with certain lengths are reserved on the end faces of the two fibers to form an F-P cavity, so that the EFPI structure is formed. The two ends of the glass tube are fixed by strong glue to form glue bonding points 7 and 10, and the optical fiber in the glass tube is in a free state. The EFPI-FBG composite sensor before being packaged is shown in FIG. 2. The incident optical fiber placed in the copper tube 13 is engraved with the grating 12, and the two ends of the optical fiber grating adhere the two ends of the copper tube by using AB glue to form glue bonding points 11 and 14. The grating is in a free bending state and is free from stress, and is used for temperature detection. And completely embedding the manufactured EFPI structure into epoxy resin 5, and embedding a part of the copper pipe into the epoxy resin. And forming the pressure elastic whole after the epoxy resin is cured at normal temperature. The interior of the metal shell 3 is coated with solid lubricating grease 4, so that the epoxy resin adhesive is prevented from being adhered to the inner wall of the metal shell in the curing process, and the sensitivity of the sensor is increased. After the epoxy resin is solidified, the top of the epoxy resin is sealed by using the sealant 2, the other part of the copper pipe is embedded into the sealant, the sealing length is 15mm, and liquid is prevented from leaking when the sensor measures the pressure of the pipeline. And the left end of the metal shell is connected with the end cover 16 through the threads 15, so that the epoxy resin elastomer in the metal shell is prevented from being extruded by high-pressure oil when the high-pressure action is applied. The outer side end of the metal shell is provided with an outer taper pipe thread 6 which can be connected with a hydraulic oil pipeline or a hydraulic joint, the sensor is connected into the oil pipeline, and pressure acts on the end face of the tail end of the epoxy resin.
As shown in fig. 3, the sensor tip is force-analyzed when it is subjected to a pressure P: the metal case is not deformed, provided that there is no friction between the inner wall of the metal case and the resin cylinder.
When the sensor is only under pressure, the thermal stress and thermal expansion influence between the epoxy resin and the quartz glass tube caused by temperature change are not considered.
In the case where the silica glass tube is not embedded in the epoxy resin cylinder, the amount of strain generated by the compression of the epoxy resin under the action of the pressure at one end is calculated by the following formula:
in the formula: p is the liquid pressure, E1Is the elastic modulus, mu, of an epoxy resin1Is the Poisson ratio of the epoxy resin.
When the epoxy resin is embedded in the quartz glass tube, it is assumed that the quartz glass tube and the epoxy resin are completely consolidated together. The strain capacity of the quartz glass tube is equal to that of the epoxy resin within the length of the glass tube L. Since the elastic modulus of the quartz glass tube is much larger than that of the epoxy resin, the influence of the epoxy resin on the strain in the radial direction of the quartz glass tube is ignored. The strain expression of the epoxy resin between stages with glass tubes can be found:
in the formula: e2Is the modulus of elasticity, s, of a quartz glass tube1Is the cross-sectional area of the epoxy resin, s2Is the cross-sectional area, s, of the quartz glass tube3Is the inner ring area of the quartz glass tube.
And (3) analyzing the stress of the sensor when the temperature changes:
when the sensor is subjected to temperature only, the epoxy resin and the quartz glass tube generate thermal strain. Meanwhile, the two are solidified together, but the thermal expansion coefficients are different, and elastic strain is generated between the two due to temperature change.
The epoxy resin is consolidated with the glass tube, and the strain capacity of the quartz glass tube is equal to that of the epoxy resin within the length of the glass tube L. The expression of the axial strain of the quartz glass tube caused by the temperature in a certain temperature variation range can be obtained:
in the formula: alpha is alpha1Is the coefficient of thermal expansion, alpha, of the epoxy resin2Is the thermal expansion coefficient of the quartz glass tube.
The bare fiber in the glass tube is in a free state, and two ends of the bare fiber are fixed by glue. The change of the length of the Fabry-Perot cavity is equal to the change of the axial length of the glass tube. Namely a Fabry-Perot cavity length variation expression:
Δl＝L0∑ε (4)
in the formula: l is0The initial length of the quartz glass tube, and Σ ∈ is the average strain occurring over the axial length of the glass tube.
The thermal expansion effect and the thermo-optic effect of the fiber bragg grating in a free state in the copper pipe caused by the temperature change can cause the reflection wavelength of the fiber bragg grating to shift, and the relationship is as follows:
Δλ/λ0＝(α+ξ)ΔT＝K3ΔT (5)
in the formula: lambda [ alpha ]0The central wavelength of the fiber grating is shown, alpha is the thermal expansion coefficient, and xi is the thermo-optic coefficient.
Example three: an EFPI-FBG composite pressure and temperature sensor measuring method comprises the following steps:
1. the incident bare fiber 1 and the reflecting bare fiber 8 with the grating are respectively inserted into the quartz glass tube 9 from two ends, and two end faces form an F-P cavity. The two ends of the glass tube are fixed by the super glue to form the gluing points 7 and 10.
2. And packaging the grating 12 outside the glass tube in a copper tube, fixing the optical fiber and the two ends of the copper tube by AB glue to form gluing points 11 and 14 when the grating is in a free bending state.
3. The glass tube is completely encapsulated in the cylindrical epoxy resin 5, and the glass tube is positioned in the center of the epoxy resin to form the pressure elastic body. While a portion of the copper tube 13 is embedded in the epoxy resin.
4. And (3) coating solid lubricating grease 4 on the inner wall of the metal shell 3, wherein the coating length is consistent with that of the pressure elastomer. The encapsulated pressure elastomer is sleeved in the metal shell.
5. The sealing glue 2 is added to the top of the metal shell, and the other part of the copper tube is completely embedded into the sealing glue. And a part of the optical fiber jumper 17 is embedded in the sealant to protect the internal optical fiber.
6. The left end of the metal shell is connected with an end cover 166 through threads 15;
7. and connecting the manufactured EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging into a hydraulic pipeline through the taper pipe external thread 6. And connecting a jumper wire into the FP-FBG composite demodulator.
8. Fabry-Perot cavity length variation delta l measured by FP-FBG composite demodulator1And a fiber grating wavelength shift Δ λ.
9. The temperature change delta T is obtained through the wavelength drift delta lambda of the fiber bragg grating, so that the cavity length change delta l of the Fabry-Perot cavity caused by the temperature change of the sensor is obtained2。
10. Fabry-Perot cavity length change delta l-delta l caused by hydraulic oil pressure in hydraulic pipeline1±Δl2And further obtaining the hydraulic oil pressure in the hydraulic pipeline.
It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (10)
1. An EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging is characterized in that a sensing head of the sensor comprises an incident bare fiber, a reflection bare fiber, a glass tube, a copper tube, a metal shell and an end cover; one part of the incident bare fiber and one part of the reflection bare fiber are inserted into the glass tube, the other part of the incident bare fiber and the reflection bare fiber are positioned outside the glass tube, and an optical fiber F-P cavity is formed between the end surfaces of the two optical fibers in the glass tube; the incident bare fiber and the reflecting bare fiber are respectively fixed with the inner wall of the glass tube, the optical fiber in the glass tube is in a free state, the incident optical fiber is engraved with a grating and is positioned outside the glass tube, the optical fiber grating is packaged in the copper tube, and two ends of the optical fiber grating are fixed with two ends of the copper tube.
2. The EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation of claim 1, wherein the fixed length of the incident bare fiber, the reflection bare fiber and the inner wall of the glass tube is 2-3 mm.
3. The EFPI-FBG composite pressure and temperature sensor based on epoxy resin package as claimed in claim 1 or 2, wherein the epoxy resin completely wraps the glass tube, and the end face of the epoxy resin has a distance margin with the end face of the glass tube.
4. The EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation as claimed in claim 3, wherein a layer of grease is coated between the epoxy resin and the inner wall of the metal shell.
5. The EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation as claimed in claim 3, wherein the top is sealed with a sealant after epoxy resin curing, and the sealant thickness is more than 10 mm.
6. The EFPI-FBG composite pressure and temperature sensor based on the epoxy resin package as claimed in claim 1 or 2, wherein one end of the metal shell is provided with an outer taper pipe thread connected with a hydraulic pipeline; the other end of the metal shell is connected with the end cover through threads.
7. The EFPI-FBG composite pressure and temperature sensor based on epoxy resin encapsulation as claimed in claim 3, wherein the glass tube is completely encapsulated in the cylindrical epoxy resin, and the glass tube is located at the center of the epoxy resin to form a pressure elastic body.
8. The epoxy-encapsulated EFPI-FBG composite pressure and temperature sensor of claim 3 wherein said glass tube is a quartz glass tube.
9. The measuring method of the EFPI-FBG composite pressure and temperature sensor is characterized by comprising the following steps,
step one, respectively inserting an incident bare fiber and a reflection bare fiber which are engraved with gratings into a glass tube from two ends, forming an F-P cavity on two end faces, and fixing the optical fibers at two ends of the glass tube by using glue;
step two, packaging the optical grating outside the glass tube in the copper tube, enabling the optical grating to be in a free bending state, and fixing the optical fiber and the two ends of the copper tube by using glue;
completely packaging the glass tube in cylindrical epoxy resin, wherein the glass tube is positioned in the center of the epoxy resin to form a pressure elastomer, and meanwhile, a part of the copper tube is embedded in the epoxy resin;
coating solid lubricating grease on the inner wall of the metal shell, wherein the coating length is consistent with that of the pressure elastomer, and the packaged pressure elastomer is sleeved in the metal shell;
adding sealant to the top of the metal shell, and completely embedding the other part of the copper pipe into the sealant; one part of the optical fiber jumper is embedded into the sealant;
step six, the left end part of the metal shell is connected with the end cover through threads;
and step seven, connecting the manufactured EFPI-FBG composite pressure and temperature sensor based on epoxy resin packaging into a hydraulic pipeline through a taper pipe external thread, and connecting a jumper into the FP-FBG composite demodulator.
10. The EFPI-FBG composite pressure and temperature sensor measuring method according to claim 9, wherein the Fabry-Perot cavity length variation Deltal is measured by using an FP-FBG composite demodulator1And the fiber grating wavelength drift amount delta lambda; the temperature change delta T is obtained through the wavelength drift delta lambda of the fiber bragg grating, so that the cavity length change delta l of the Fabry-Perot cavity caused by the temperature change of the sensor is obtained2(ii) a Fabry-Perot cavity length change delta l-delta l caused by hydraulic oil pressure in hydraulic pipeline1±Δl2And further obtaining the hydraulic oil pressure in the hydraulic pipeline.
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| CN114325967A (en) * | 2021-12-30 | 2022-04-12 | 昂纳信息技术（深圳）有限公司 | Optical device sealing structure and sealing method |
| CN114739434A (en) * | 2022-04-27 | 2022-07-12 | 兰州大学 | Flexible packaging method for distributed optical fiber sensing device |
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| CN114777836A (en) * | 2022-03-10 | 2022-07-22 | 吉林大学 | Optical fiber high-temperature stress sensor based on yttrium aluminum garnet crystal derived optical fiber and preparation method thereof |
| CN114777836B (en) * | 2022-03-10 | 2023-12-05 | 吉林大学 | Optical fiber high-temperature stress sensor based on yttrium aluminum garnet crystal derived optical fiber and preparation method thereof |
| CN114739434A (en) * | 2022-04-27 | 2022-07-12 | 兰州大学 | Flexible packaging method for distributed optical fiber sensing device |
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