CN212409940U

CN212409940U - Fish-shaped fiber grating wide-range pressure sensor

Info

Publication number: CN212409940U
Application number: CN202020234435.3U
Authority: CN
Inventors: 王洪涛; 黄爱武; 王一烁
Original assignee: Weifang Jiateng Hydraulic Technology Co ltd
Current assignee: Weifang Jiateng Hydraulic Technology Co ltd
Priority date: 2020-02-29
Filing date: 2020-02-29
Publication date: 2021-01-26
Anticipated expiration: 2030-02-28

Abstract

The utility model relates to a fish type fiber grating wide range pressure sensor is suitable for the fluid pressure in the detection pipeline, including the skeleton, the skeleton comprises the sheetmetal that two mutual symmetries set up, and the sheetmetal is established to the horizontal short thin slice structure of vertical length, and the setting of outside uplift respectively of intermediate part of two sheetmetals makes to form a cavity between two sheetmetals, is equipped with the gasbag of similar fish bubble in the cavity, is equipped with the filler between gasbag and the sheetmetal. The utility model designs a fishbone-shaped metal sheet according to the bionics principle of the fish body, and sets fiber gratings at the inner and outer sides of the central axis of the 'fish line' of the metal sheet, wherein two fiber gratings at two sides of one metal sheet eliminate the influence of temperature on the grating by using the positive and negative deformation principle of the metal sheet, and realize the pressure detection of temperature self-compensation; the metal sheet on the other side is provided with concave or convex rib grooves, so that the supporting effect of the metal sheet on the radial elliptic deformation of the fiber bragg grating is strengthened, and the medium-high voltage is detected by utilizing the resonance wavelength splitting relay of the birefringence.

Description

Fish-shaped fiber grating wide-range pressure sensor

Technical Field

The utility model relates to an optical fiber sensing technical field and hydraulic pressure detection technical field, concretely relates to fish type fiber grating wide range pressure sensor.

Background

From bernoulli's equation, the pressure of the fluid in the pipeline is also a form of energy, and in a hydraulic transmission system, the flow rate (kinetic energy) of the medium is low, the potential energy generated is relatively low, and the so-called hydrostatic transmission can be considered, namely, the transmission of power only depends on the pressure energy of the working medium. In hydrostatic transmission, fluid pressure in a pipeline can be changed due to opening and closing of a pump or a valve or dynamic change of a load, and particularly, research on distribution and dynamic characteristics of pressure in a spiral pipeline is still a technical blank at present.

The traditional liquid pressure sensing device is mainly a mechanical pressure gauge or a resistance-type pressure sensor, the detection methods have the advantages of relatively mature measurement theory and technology and low equipment cost, but the method of forming a detection process hole in the radial direction of a pipeline and installing a pressure or high-frequency response pressure sensor probe on the radial side wall of the pipeline is generally adopted when the internal pressure or pressure response of the hydraulic pipeline is detected at present.

However, the above method has certain problems: firstly, damaging a pipeline side wall structure; secondly, the probe of the radial sensor destroys the laminar flow form of the liquid flow on the inner wall and increases the internal disturbance of the liquid flow; thirdly, the flow velocity inside and outside the spiral pipeline is different, the pressure state is different, and the method of adopting a fixed pressure sensor probe is difficult to accurately measure the pressure distribution and the change rule in the pipeline.

In view of the disadvantages of the above methods, the prior art has appeared instruments applicable to pressure measurement of liquid in pipelines, most of such instruments are implemented by using the fiber grating principle, but when a fiber grating pressure sensor is used for pressure measurement, the problems of small bearing capacity and small measurement pressure range exist. Therefore, at present, a cantilever beam amplification principle is generally adopted to package the pressure sensor so as to solve the problem of small bearing capacity of the sensor, but the problem of increased volume of the sensor is generated at the same time, and the problem of small measurement pressure range of the sensor cannot be solved by packaging the sensor, namely the measuring range of the sensor still cannot meet the actual requirement of the engineering hydraulic machinery.

In the prior art, there are two main methods for measuring pressure by using fiber gratings: firstly, a certain linear relation can be established between the wavelength of the fiber bragg grating and the physical quantity to be measured, and the drift value of the wavelength caused by the change of the physical quantity to be measured is converted into a corresponding pressure value by calibrating the linear coefficient in the linear range. For example, when the fiber bragg grating is subjected to an external field (stress field, temperature field, etc.), the grating period or effective refractive index of the fiber bragg grating changes to cause the wavelength shift of the reflection (or transmission) of the grating, and most fiber bragg grating sensors in the commonly used grating sensing belong to the category; the polarization characteristic of the fiber bragg grating can establish a linear relation with the physical quantity to be detected, the polarization characteristic changes along with the change of the physical quantity to be detected, the resonance wavelength of the fiber bragg grating under the pressure load condition is split, and the external pressure is detected through the offset of the central wavelength of the amplitude spectrum of the x polarized light and the central wavelength of the y polarized light, but when the method is in a condition of small pressure, the difference of the central wavelengths of two eigenmodes is difficult to detect through the total amplitude spectrum.

In summary, because the fiber grating sensor has high sensitivity, both the grating center wavelength drift amount and the birefringence detection method caused by the fiber elliptic deformation have a range that can only detect low pressure and a range that can only detect relative high pressure, so that the measuring range of the measured pressure is greatly limited, and the lower limit or the upper limit of the pressure detectable by the fiber grating sensor at present can not meet the actual requirements of the engineering hydraulic machinery.

Therefore, a pipeline nondestructive testing system capable of realizing a fiber grating wide-range pressure sensor with higher precision in a hydraulic pipe is needed, and is used for collecting high-precision pressure data of oil pressure in the pipeline.

The utility model discloses measure the nerve perception principle of fish "the fish line of fish" to fluid pressure with the help of the development of current fiber grating technique, the comprehensive utilization fiber grating vertically and radially along with the pressure variation and the complementarity of two outstanding characteristics of measuring range difference, main innovation a bionical fish type fiber grating wide range pressure sensor.

SUMMERY OF THE UTILITY MODEL

The utility model provides a fish type fiber grating wide range pressure sensor, its structural design is reasonable, according to the bionics principle of the inferior symmetrical structure of fish body, the design has the sheetmetal of the fishbone shape of rigidity difference in the fish body left and right sides, and inside has the gasbag of similar fish bubble, is equipped with the elasticity filler between gasbag and the sheetmetal to set up the grating sensor on the optic fibre of the inside and outside both sides of axis of sheetmetal. The metal sheet of the sensor framework is divided into a positive metal sheet and a negative metal sheet, the negative metal sheet is provided with through grooves along the upper side and the lower side of the grating, the negative metal sheet plays a role of a strain diaphragm at low pressure, so that the negative metal sheet can quickly deform and respond at low pressure, and the fiber bragg gratings on the surface of the negative metal sheet are sequentially numbered as 1 and 2 from outside to inside; in a low-pressure measurement range, the temperature influence is eliminated by utilizing the positive and negative deformation principle of the two grating sensors, so that the pressure detection of temperature self-compensation is realized; the thickness of the male metal sheet can be thickened relative to one side of the female metal sheet as required, or convex or concave reinforcing rib grooves are arranged along the surface of the male metal sheet, so that the anti-deformation capability of the male metal sheet is greater than that of the female metal sheet, the grating on the outermost side is supported to firstly generate radial elliptical deformation under external pressure, the characteristic light signal generates resonance wavelength splitting under the pressure load condition, the external pressure is detected through the change of the characteristic light signal, and the elliptical deformation is generated when the grating on the inner side of the male metal sheet is subjected to larger external pressure due to the energy absorption of the elastic part of the fish body, so that higher pressure can be detected, and the elliptical deformation of the grating on the inner side and the outer side of the male metal sheet is not influenced by temperature. Therefore, the structure is suitable for large-range hydraulic pressure detection, and the problems of low detection pressure and small range of the conventional fiber grating sensor are solved.

The utility model discloses a solve the technical scheme that above-mentioned technical problem adopted and be: a fish-type fiber grating wide-range pressure sensor suitable for detecting the liquid pressure in a pipeline comprises:

the framework is composed of two metal sheets which are symmetrically arranged, the metal sheets are in a longitudinal long and transverse short sheet structure, the middle parts of the two metal sheets are respectively arranged in an outward protruding mode, a cavity is formed between the two metal sheets, an air bag similar to a fish bubble is arranged in the cavity, and fillers are arranged between the air bag and the metal sheets; at least two grooves are transversely formed in the metal sheet, the grooves are symmetrically arranged about a longitudinal central axis of the metal sheet, and a plurality of supporting parts which are matched with each other are formed at the parts left beside the two grooves of the metal sheet;

two optical fibers are arranged on the side wall of each metal sheet along the central axis, the two optical fibers are symmetrical relative to the inside and the outside of the metal sheet, a grating is respectively recorded in the middle of the metal sheet on each optical fiber, and the grating characteristic values on each metal sheet are the same (the grating grid periods are the same, the recording depths are the same, and the grid lengths are the same); the four optical fibers on the two metal sheets are numbered, the four optical fibers with different numbers form an optical cable from two ends of the framework in sequence, and the optical cable can be connected with the optical fiber connectors of the four channels;

two longitudinal ends of each metal sheet are respectively provided with a connecting hole, a connecting piece is arranged between the two metal sheets, and the connecting piece penetrates through the two connecting holes to enable the two metal sheets to form an interconnected structure; the connecting piece is connected with the optical fiber connector through a traction rope, and the traction rope is arranged in the optical cable formed by the optical fibers;

when the fish-shaped fiber grating pressure sensor is subjected to liquid pressure in a pipeline, the fiber gratings on the inner and outer walls of the metal sheet with weak deformation resistance in the two metal sheets of the framework are firstly subjected to positive and negative deformation along the longitudinal direction of the framework, and the pressure detection of temperature self-compensation is realized by collecting the difference value of the central wavelength drift amounts of the two fiber gratings subjected to positive and negative deformation; when the pressure in the pipeline rises to a certain threshold value, because the supporting parts of the two metal sheets are mutually contacted and supported, firstly, the outside fiber bragg gratings on the metal sheets with strong anti-deformation capability in the two metal sheets of the framework are radially deformed in an elliptical manner, so that the change of characteristic light signals is caused to detect the external pressure; secondly, when the pressure continuously rises to reach a higher threshold value, the liquid pressure acts on the fiber bragg grating on the inner side of the other metal sheet through the metal sheet with weak anti-deformation capability, the air bag and the filler of the two metal sheets of the framework, so that the cross section of the fiber bragg grating on the inner side of the metal sheet with strong anti-deformation capability of the two metal sheets of the framework is radially deformed in an elliptical manner, and a characteristic light signal is changed to detect higher external pressure; the threshold is a critical value of a corresponding optical signal which can be detected by the relevant fiber bragg grating;

the surface skin is a framework and a film packaged outside the optical cable, and the film is compatible with a hydraulic medium material in the pipeline.

Furthermore, the traction rope and the four optical fibers form two end optical cables along the arrangement direction of the four optical fibers, and the optical cables can be connected with the optical fiber connectors of the four channels or connected with the end optical cable of the next fish-shaped fiber bragg grating pressure sensor; two torsion-resistant ropes are arranged between the adjacent connecting pieces between the frameworks, and the torsion-resistant ropes are connected with the two end parts of the connecting pieces penetrating out of the metal sheets.

Furthermore, the positions of the two metal sheets corresponding to the connecting holes are not in contact with each other, and when the filler and the air bag are in the state of maximum deformation, the gap between the positions of the connecting holes of the two metal sheets is not smaller than the diameter of the optical fiber.

Further, inert gas or other non-toxic gas is arranged in the air bag, the filler is elastic filler, and the elastic filler comprises rubber or resin.

Further, the supporting part quantity that the sheetmetal homonymy set up establishes to 3 to 5, receives liquid pressure when the skeleton after, two the supporting part that the sheetmetal corresponds can butt each other to increase the whole modulus of elasticity of skeleton.

Furthermore, an included angle is formed between the supporting part and the metal sheet, so that the supporting part is arranged in a tilting manner, and the supporting parts corresponding to the two metal sheets form a contact surface; after the framework is pressed, the corresponding supporting parts are mutually abutted, or the filler is arranged between the supporting parts, so that the supporting parts are abutted with the filler.

Furthermore, the framework is provided with a male surface and a female surface, through grooves are dug in the metal sheet corresponding to the female surface along the upper side and the lower side of the grating, so that the metal sheet between the grooves can quickly deform and respond to low pressure to form a movable metal sheet, and the fiber gratings on the surface of the movable metal sheet are sequentially numbered as 1 and 2 from outside to inside; the thickness of the metal sheet corresponding to the male surface can be thickened relative to one side of the female surface as required, or convex or concave reinforcing rib grooves are arranged along the surface of the male surface metal sheet, so that the anti-deformation capacity of the male surface metal sheet is greater than that of the female surface metal sheet, and the fiber bragg gratings on the surface of the male surface metal sheet are sequentially numbered as 3 and 4 from inside to outside.

Further, the appearance of skeleton is the fish type, the horizontal both sides of sheetmetal set up the supporting part and are trapezoidal toe form, guarantee the reliable contact of butt part large tracts of land between two arch sheetmetals to the whole ability that bears the interior fluid pressure of pipeline of reinforcing skeleton.

Furthermore, when the framework is subjected to liquid pressure which changes from small to large, the deformation characteristic of the shape of the framework is in a step shape, and the detection of the pressure is completed by the assembling force of the gratings at the two sides of the framework;

the cavity parts corresponding to the metal sheets have different longitudinal and transverse deformation under different pressures, and in the process of increasing the liquid pressure from small to large, the deformation of the framework is mainly increased towards the longitudinal two sides to drive the period of the grating grids adhered on the framework to be increased, the deformation of the metal sheet on the negative side is larger than that of the metal sheet on the positive side, and in this stage, the influence of the temperature on the longitudinal change of the grating is eliminated by mainly utilizing the positive and negative deformation principle of the metal sheets through the longitudinal change of the two fiber gratings on the two sides of the metal sheet on the negative side, so that the pressure detection of temperature self-compensation is realized;

in the second stage, along with the continuous increase of the liquid pressure, the supporting parts of the metal sheets are mutually folded and abutted, the whole elastic modulus is stepped to be improved, the deformation of the two longitudinal ends of the metal sheets is reduced, the detection sensitivity of the longitudinal deformation of the two fiber gratings on the two sides of the metal sheet on the female side of the framework is reduced, the fiber gratings arranged on the outer side of the male metal sheet with strong deformation resistance are firstly deformed in an elliptic manner under the supporting force action of the liquid pressure and the metal sheet to cause the resonance splitting of optical signals, and the external pressure is detected by collecting the change of characteristic optical signals in the gratings;

and in the third stage, as the liquid pressure continues to rise, the liquid pressure acts on the fiber bragg grating on the inner side of the male metal sheet through the movable metal sheet, the air bag and the elastic filler on the female metal sheet, so that the cross section of the fiber bragg grating on the inner side of the male metal sheet is deformed in an elliptic mode subsequently to cause resonance splitting of optical signals, and higher external pressure is detected by collecting the change of characteristic optical signals in the grating.

Furthermore, a plurality of the sensors are mutually connected in series through optical fiber or four-channel optical fiber connectors, so that a plurality of optical fiber grating sensors are used in a combined state, the grating on the outer side is connected with the grating on the outer side, the grating on the inner side is connected with the grating on the inner side, the gratings on the same side are guaranteed to be grouped, the serial number and the identification of the optical fiber connectors are clear, and the sequence is regular.

The utility model adopts the above structure beneficial effect be, its structural design is reasonable, according to the bionics principle of the inferior symmetrical structure of the fish body, has the sheetmetal of the fishbone shape that rigidity is different in the design of the fish body left and right sides, and inside has the gasbag of similar fish bubble, is equipped with the elasticity filler between gasbag and the sheetmetal to set up the grating sensor on the optic fibre of the inside and outside both sides of axis of sheetmetal. The metal sheet of the sensor framework is divided into a positive metal sheet and a negative metal sheet, the negative metal sheet is provided with through grooves along the upper side and the lower side of the grating, the negative metal sheet plays a role of a strain diaphragm at low pressure, so that the negative metal sheet can quickly deform and respond at low pressure, and the fiber bragg gratings on the surface of the negative metal sheet are sequentially numbered as 1 and 2 from outside to inside; in a low-pressure measurement range, the temperature influence is eliminated by utilizing the positive and negative deformation principle of the two grating sensors, so that the pressure detection of temperature self-compensation is realized; the thickness of the male metal sheet can be thickened relative to one side of the female metal sheet as required, or convex or concave reinforcing rib grooves are formed in the surface of the male metal sheet, so that the anti-deformation capacity of the male metal sheet is greater than that of the female metal sheet, the grating on the outermost side is supported to firstly generate radial elliptical deformation under external pressure, the optical signal is subjected to resonance wavelength splitting, the external pressure is detected through the change of the characteristic optical signal, and due to the energy absorption of the elastic part of the fish body, the elliptical deformation is generated when the grating on the inner side of the male metal sheet is subjected to larger external pressure, so that higher pressure can be detected, and the elliptical deformation of the grating on the inner side and the outer side of the male metal sheet is not influenced by temperature. Therefore, by packaging the fish-shaped sensor, the staged collection of axial signals and radial elliptical deformation information of the fiber bragg grating is realized, the problem that the traditional fiber bragg grating sensor is difficult to measure high pressure and low pressure simultaneously is solved, and the pressure detection range is expanded; therefore, the problems of low detection pressure and small measuring range of the conventional fiber bragg grating sensor are solved.

Secondly, the streamline and floating functions of the fish-shaped sensor with a bionic fish structure are adopted, the fish-shaped sensor can be arranged in the middle of liquid in a hydraulic pipeline without damaging the wall surface of the pipeline, and optical fibers are arranged in the pipeline in series, so that leakage points of the process holes of the pipeline wall are reduced;

finally, the sensor encapsulates a plurality of paths of fiber bragg gratings in a fish-shaped sensor with a sub-symmetrical structure, and utilizes the supporting effect of liquid pressure in a pipeline on the outer wall of the fish-shaped sensor and the elastic absorption effect of an air bag and a fish body, so that the fiber bragg gratings on the inner side of the male surface metal sheet are radially deformed in an elliptical manner when the environmental pressure is high, and the detection of ultrahigh pressure is realized through different encapsulating materials.

Therefore, the structure is suitable for large-range hydraulic pressure detection, and the problems of low detection pressure and small range of the conventional fiber grating sensor are solved.

Drawings

Fig. 1 is a schematic sectional view of the present invention.

Fig. 2 is the expanded structure diagram of the corresponding angle of the female metal sheet of the present invention.

Fig. 3 is a schematic view of the unfolding structure of the male-surface metal sheet of the present invention.

Fig. 4 is a schematic perspective view of the skeleton part of the present invention.

Fig. 5 is a side view of the structure of fig. 4.

In the figure, 1, a skeleton; 2. a metal sheet; 201. a negative side metal sheet; 202. a male-side metal sheet; 3. a cavity; 4. an air bag; 5. a filler; 6. a groove; 7. a support portion; 8. an optical fiber; 9. a grating; 10. an optical cable; 11. connecting holes; 12. a hauling rope; 13. a connecting member; 14. a torsion resistant rope; 15. an optical fiber connector; 16. a trench; 17. a convex or concave bead groove.

Detailed Description

In order to clearly illustrate the technical features of the present invention, the present invention is explained in detail by the following embodiments in combination with the accompanying drawings.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, the present application may be practiced in other ways than those described herein, and therefore the scope of the present application is not limited by the specific embodiments disclosed below.

In addition, in the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", and the like, indicate orientations and positional relationships based on those shown in the drawings, are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

As shown in fig. 1-5, a fish-shaped fiber grating wide-range pressure sensor, suitable for detecting the liquid pressure in the pipeline, includes a frame 1, the frame 1 is composed of two female-side metal sheets 201 and male-side metal sheets 202 which are symmetrically arranged, the female-side metal sheets 201 and the male-side metal sheets 202 are arranged in a longitudinal long and transverse short sheet structure, the middle parts of the two metal sheets 2 are respectively arranged in an outward protruding manner, so that a cavity 3 is formed between the two metal sheets 2, an air bag 4 similar to fish bubbles is arranged in the cavity 3, and a filler 5 is arranged between the air bag 4 and the metal sheets 2; the metal sheet 2 is provided with at least two grooves 6, the grooves 6 are symmetrically arranged about the longitudinal central axis of the metal sheet 2, so that the two metal sheets 2 form a plurality of supporting parts 7 which are matched with each other; two optical fibers 8 are arranged on the side wall of each metal sheet 2 along the central axis, the two optical fibers 8 are symmetrical inside and outside with respect to the metal sheet 2, a grating 9 is respectively recorded on each optical fiber 8, the characteristic values of the gratings 9 on each metal sheet 2 are the same (the grating grid periods are the same, the recording depths are the same, and the grid lengths are the same), and the gratings 9 on each metal sheet 2 are symmetrical inside and outside along the longitudinal length of the metal sheet 2; the four optical fibers 8 on the two metal sheets are numbered, the four optical fibers 8 with different numbers sequentially form an optical cable 10 from two ends of the framework 1, and the optical cable 10 can be connected with four-channel optical fiber connectors 11; two longitudinal ends of each metal sheet 2 are respectively provided with a connecting hole 11, a connecting piece 13 is arranged between the two metal sheets 2, and the connecting piece 13 penetrates through the two connecting holes 11 to enable the two metal sheets 2 to form an interconnected structure; the connecting piece 13 is connected with the optical fiber connector 15 through a pulling rope 12, and the pulling rope 12 is arranged in the optical cable 10 formed by the optical fiber 8; when the fish-shaped fiber grating pressure sensor is subjected to liquid pressure in a pipeline, the grooves are symmetrically formed in the female metal sheet 201 along the two sides of the fiber grating, the fish-shaped fiber grating pressure sensor is easy to deform and plays a role of a strain diaphragm, so that the working principle of eliminating temperature influence similar to a spring tube type fiber grating pressure sensor is realized, and the pressure detection of temperature self-compensation is realized; when the pressure in the pipeline rises to a certain threshold value, the supporting parts 7 of the two metal sheets 2 are mutually contacted and supported, so that the fiber bragg grating on the outer side of the male metal sheet 202 is radially deformed in an elliptical manner, the resonance wavelength of an optical signal is split, the external pressure is detected through the change of a characteristic optical signal, when the pressure rises to a higher threshold value again, the fiber bragg grating on the inner side of the male metal sheet 18 is radially deformed in an elliptical manner, the resonance wavelength of the optical signal is split, and the external higher pressure is detected through the change of the characteristic optical signal; and the frame 1 and the optical cable 9 are externally packaged with skins which are made into films, and the films are compatible with hydraulic medium materials in the pipeline. When the device is used, according to the bionics principle of deep sea fishes for sensing water pressure, a fishbone-shaped metal sheet is designed, according to the bionics principle of fish 'thenar line' for sensing water pressure and a generally existing sub-symmetrical structure in the biological world, a framework 1 is provided with a male surface and a female surface, a fishbone-shaped female surface metal sheet 201 and a fishbone-shaped male surface metal sheet 202 are designed, two optical fibers are arranged at two sides of the 'thenar line' of the metal sheet, grating sensors are arranged at the inner side and the outer side of a central axis of the metal sheet 2, the female surface metal sheet 201 is provided with through grooves 16 along the upper side and the lower side of a grating, and the function of a strain diaphragm is achieved at low pressure; in a low-pressure measurement range, the temperature influence is eliminated by utilizing the positive and negative deformation principle of the two grating sensors, so that the pressure detection of temperature self-compensation is realized; in the middle-high pressure measurement range, the optical fiber and the optical grating between the pipeline liquid and the male surface metal sheet 202 are subjected to radial elliptical deformation under the action of pressure, so that the resonance wavelength of the optical grating under the pressure load condition is split, the external pressure is detected through the change of the characteristic optical signal, and the elliptical deformation is not influenced by the temperature. Therefore, higher pressure can be detected, so that the structure is suitable for large-range hydraulic pressure detection, and the problems of low detection pressure and small range of the conventional fiber grating sensor are solved.

It should be noted that the optical fiber 8 is adhered along the surfaces of the female metal sheet 201 and the male metal sheet 202, and the female metal sheet 201 and the male metal sheet 202 are made of titanium or titanium alloy with light weight and high strength.

In a preferred embodiment, the pulling rope 12 and the four optical fibers 8 form two end cables 10 along the arrangement direction of the four optical fibers 8, and the cables 10 can be connected with a four-channel optical fiber connector 15 or connected with the end cable 10 of the next fish-shaped fiber grating pressure sensor; two torsion-resistant ropes 14 are arranged between the connecting pieces 13 between the adjacent frameworks 1, the torsion-resistant ropes 14 and the connecting pieces 13 penetrate through two end parts of the metal sheets 2 to be connected, and a torsion-resistant torque arm is established by means of the hole pitch between the metal sheets 2 at the male side and the female side.

Additionally, the length of the fiber optic cable 10 or pull cord 12 may be more than ten times the lateral length of the fish sensor or fiber optic connector 15 at the forward end thereof to avoid upstream objects affecting the next sensor pressure by rear turbulence. An oil-compatible film is suspended between the torsion resistant cord 14 and the optical cable 10 to provide torsional balance by fluid flow.

Specifically, the connecting member 13 is a metal rod structure, and the connecting rings are respectively disposed at the middle portion and both ends of the connecting member 13, so that the connecting ring structure can be directly manufactured by knotting the connecting member 13 itself, so as to connect the traction rope 12 and the torsion resistant rope 14.

In the preferred embodiment, the two metal sheets 2 are arranged in a manner of not contacting each other at the positions corresponding to the connection holes 11, and when the filler 5 and the balloon 4 are in the state of maximum deformation, the gap between the positions of the connection holes 11 of the two metal sheets 2 is not smaller than the diameter dimension of the optical fiber 8. As shown in fig. 5, the corresponding positions at the two ends of the metal sheet 2 are provided with notches, and after the main body parts of the metal sheet 2 are mutually abutted, the two end positions where the optical fibers pass through are still left with gaps, so that the optical fibers cannot be extruded and damaged, the gaps between the two metal sheets 2 are limited in the embodiment, the framework 1 is prevented from extruding the optical fibers 8 by the female metal sheet 201 and the male metal sheet 202 after receiving external pressure, and the effect of protecting the optical fibers 8 is achieved.

In the preferred embodiment, the bladder 4 is filled with an inert gas or other non-toxic gas, and the filler 5 is provided as an elastomeric filler, which may comprise a rubber or resin type.

In a preferred embodiment, the number of the supporting portions 7 disposed on the same side of the metal sheet 2 is set to 3 to 5, and when the framework 1 is subjected to the liquid pressure, the supporting portions 7 corresponding to the female metal sheet 201 and the male metal sheet 202 can abut against each other, so as to increase the overall elastic modulus of the framework 1.

In a preferred embodiment, an included angle is formed between the supporting portion 7 and the metal sheets, so that the supporting portion 7 is tilted, and the supporting portions corresponding to the two metal sheets 7 form a contact surface; after the frame 1 is pressed, the corresponding support portions 7 are abutted against each other, or the filler 5 is provided between the support portions 7, and the support portions 7 and the filler 5 are abutted against each other. The present embodiment further optimizes the arrangement of the supporting portion 7, so that the supporting portion 7 forms a structure similar to the shape of a toe, and forms a plurality of surface contacts, thereby improving the stability of the whole framework 1.

In a preferred embodiment, the framework 1 is provided with a male surface and a female surface, the metal sheet corresponding to the female surface is the female surface metal sheet 201, and through grooves 16 are dug along the upper side and the lower side of the grating 9, so that the female surface metal sheet 201 among the grooves 16 can quickly deform and respond at low pressure to form a movable metal sheet, and the fiber gratings on the surface of the movable metal sheet are numbered as 1 and 2 from outside to inside in sequence; the metal sheet corresponding to the male surface is that the thickness of the male surface metal sheet 202 can be thickened relative to one side of the female surface as required, or a convex or concave reinforcing rib groove 17 is arranged along the surface of the male surface metal sheet 202, so that the anti-deformation capability of the male surface metal sheet 202 is greater than that of the female surface metal sheet 2, and the fiber bragg gratings on the surface of the male surface metal sheet 202 are numbered as 3 and 4 from inside to outside in sequence.

In the preferred embodiment, the shape of the framework 1 is fish-shaped, the supporting parts 7 arranged at the two transverse sides of the metal sheet 2 are trapezoidal toe-shaped, and the large-area reliable contact of the abutting parts between the two arched metal sheets 2 is ensured, so that the capability of the framework 1 for bearing the liquid pressure in the pipeline is enhanced.

In the preferred embodiment, when the framework 1 is subjected to liquid pressure which changes from small to large, the deformation characteristic of the shape is in a step shape, and the detection of the pressure is completed by the relay of the grating groups at the two sides of the framework 1;

the corresponding cavity 3 position of the metal sheet 2 is under different pressures, the longitudinal and horizontal deflection is different, in the increasing process of the liquid pressure from small to large, the deflection of the framework 1 is mainly enlarged towards the longitudinal two sides, the grating period pasted on the framework is driven to be enlarged, the deformation of the metal sheet 201 on the negative side is larger than that of the metal sheet 202 on the positive side, at this stage, the influence of the temperature on the grating is eliminated by mainly using the positive and negative deformation principle of the metal sheet 2 through the two fiber gratings on the two sides of the metal sheet 201 on the negative side, and the pressure detection of the temperature self-compensation is realized;

in the second stage, as the liquid pressure is continuously increased, the supporting parts of the metal sheet 2 are mutually folded and abutted, the whole elastic modulus is improved in a step-like manner, the deformation of the two longitudinal ends of the metal sheet 2 is reduced, the detection sensitivity of the longitudinal deformation of the two groups of fiber bragg gratings on the two sides of the framework 1 is reduced, the fiber bragg grating arranged on the outer side of the metal sheet 2 with strong deformation resistance firstly generates elliptical deformation under the action of the liquid pressure and the supporting force of the metal sheet 2, the cross section of the fiber bragg grating on the outer side of the male metal sheet 202 generates resonance splitting of optical signals, and the external pressure is detected by collecting the change of characteristic optical signals in the gratings;

in the third stage, as the liquid pressure continues to rise, the liquid pressure acts on the fiber bragg grating on the inner side of the male metal sheet 2 through the female metal sheet 201, the air bag 4 and the elastic filler 5, so that the cross section of the fiber bragg grating on the inner side of the male metal sheet 202 is deformed in an elliptical manner, resonance splitting of optical signals is caused, and the external pressure is detected by collecting changes of characteristic optical signals in the gratings.

In a preferred embodiment, the optical fibers with the numbers of 1, 2, 3, and 4 corresponding to the numbers of the optical fibers 8 or the interfaces of the optical fiber connectors 15 are also 1, 2, 3, and 4; the optical fiber connectors 15 of the optical fibers 8 or the four channels are connected in series between the frameworks 1, so that the optical fiber grating sensors are used in a combined state, the gratings 9 on the outer side are connected with the gratings 9 on the inner side, the gratings 9 on the same side are connected with each other in a group, the serial numbers and the identifications of the interfaces of the optical fiber connectors 15 are clear, and the sequence is regular.

It should be noted that, in order to avoid that the optical fiber outside the sensor framework is interfered by the acquired characteristic light signal due to the elliptical deformation of the liquid pressure in the pipeline, the optical fiber outside the sensor framework is armored, so that the armored optical fiber section can basically eliminate the elliptical deformation of the pressure in the pipeline, and the characteristic light signal output by the optical fiber is more accurate.

The above-mentioned specific embodiments can not be regarded as the restriction to the scope of protection of the utility model, to technical personnel in this technical field, it is right the utility model discloses any replacement improvement or transform that embodiment made all fall within the scope of protection of the utility model.

The parts of the present invention not described in detail are the known techniques of those skilled in the art.

Claims

1. A fish-type fiber grating wide-range pressure sensor suitable for detecting liquid pressure in a pipeline is characterized by comprising:

two optical fibers are arranged on the side wall of each metal sheet along the central axis, the two optical fibers are symmetrical relative to the inside and the outside of the metal sheet, a grating is respectively recorded in the middle of the metal sheet on each optical fiber, the grating characteristic values on each metal sheet are the same, and the grating characteristic values are the same, namely the grating period is the same, the recording depth is the same, and the grating length is the same; the four optical fibers on the two metal sheets are numbered, the four optical fibers with different numbers form an optical cable from two ends of the framework in sequence, and the optical cable can be connected with the optical fiber connectors of the four channels;

2. The fish-shaped fiber grating wide-range pressure sensor as claimed in claim 1, wherein the pulling rope and the four optical fibers form two end cables along the arrangement direction of the four optical fibers, and the cables can be connected with the four-channel fiber connector or the end cable of the next fish-shaped fiber grating pressure sensor; two torsion-resistant ropes are arranged between the adjacent connecting pieces between the frameworks, and the torsion-resistant ropes are connected with the two end parts of the connecting pieces penetrating out of the metal sheets.

3. The fish-shaped fiber grating wide-range pressure sensor according to claim 1 or 2, wherein the two metal sheets are arranged in a non-contact manner at positions corresponding to the connecting holes, and when the filler and the balloon are in a state of maximum deformation, a gap between the positions of the connecting holes of the two metal sheets is not smaller than the diameter of the optical fiber.

4. The fish-type fiber grating wide-range pressure sensor according to claim 3, wherein an inert gas is filled in the air bag, the filler is an elastic filler, and the elastic filler comprises a rubber or resin type.

5. The large-range pressure sensor of claim 4, wherein the number of the supporting portions arranged on the same side of the metal sheet is 3 to 5, and when the framework is subjected to liquid pressure, the supporting portions corresponding to the two metal sheets can be abutted against each other to increase the overall elastic modulus of the framework.

6. The fish-shaped fiber bragg grating wide-range pressure sensor according to claim 5, wherein an included angle is formed between the supporting portion and the metal sheets, so that the supporting portion is tilted, and the supporting portions corresponding to the two metal sheets form a contact surface; after the framework is pressed, the corresponding supporting parts are mutually abutted, or the filler is arranged between the supporting parts, so that the supporting parts are abutted with the filler.

7. The fish-shaped fiber grating wide-range pressure sensor according to claim 6, wherein the framework is provided with a male surface and a female surface, and the metal sheet corresponding to the female surface is provided with through grooves along the upper and lower sides of the grating, so that the metal sheet between the grooves can quickly deform and respond to low pressure to form a movable metal sheet, and the fiber gratings on the surface of the movable metal sheet are sequentially numbered as 1 and 2 from outside to inside; the thickness of the metal sheet corresponding to the male surface can be thickened relative to one side of the female surface as required, or convex or concave reinforcing rib grooves are arranged along the surface of the male surface metal sheet, so that the anti-deformation capacity of the male surface metal sheet is greater than that of the female surface metal sheet, and the fiber bragg gratings on the surface of the male surface metal sheet are sequentially numbered as 3 and 4 from inside to outside.

8. The fish-shaped fiber grating wide-range pressure sensor as claimed in claim 7, wherein the framework is fish-shaped, the two lateral sides of the metal sheet are provided with supporting parts in a trapezoidal toe shape, so that the large-area reliable contact of the abutting parts between the two arched metal sheets is ensured, and the capability of the framework for bearing the liquid pressure in the pipeline is enhanced.

9. The fish-shaped fiber grating wide-range pressure sensor according to claim 8, wherein the plurality of sensors are connected in series via optical fibers or four-channel fiber connectors, so that the plurality of fiber grating sensors are used in a combined state, the outer grating is connected with the outer grating, the inner grating is connected with the inner grating, the gratings on the same side are guaranteed to be grouped, the serial number of the fiber connector is clearly identified, and the sequence is regular.