1. A fish-type fiber grating pressure and temperature sensor, suitable for detecting the pressure and temperature of liquid in a pipeline, comprising:

the metal sheet is in a longitudinal long and transverse short sheet structure, and longitudinal grooves are symmetrically formed in one metal sheet along two sides of a longitudinal central axis of the metal sheet and are arranged as a negative metal sheet; the other metal sheet is symmetrically provided with rib grooves protruding outwards along the longitudinal direction along the two sides of the longitudinal central axis of the other metal sheet and is set as a male surface metal sheet; the middle parts of the male metal sheet and the female metal sheet are respectively arranged in an outward protruding mode, so that 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;

the direct pressure measuring unit comprises a first optical fiber and a second optical fiber, the first optical fiber and the second optical fiber are symmetrically arranged along the longitudinal axis of the inner side wall and the outer side wall of the female metal sheet, the first optical fiber and the second optical fiber correspond to the middle of the female metal sheet, gratings are symmetrically recorded, and the grating characteristic values of the first optical fiber and the second optical fiber are the same; when the framework is subjected to liquid pressure in a pipeline, the gratings on the first optical fiber and the second optical fiber are subjected to positive and negative deformation along the longitudinal direction of the framework, so that the pressure detection of temperature self-compensation is realized;

the temperature measuring unit comprises a temperature measuring metal shell arranged in a cavity, the temperature measuring metal shell is connected with the inner wall of a male metal sheet to form a temperature measuring cavity, at least two partition plates connected with the inner wall of the temperature measuring metal shell are arranged in the temperature measuring cavity, a temperature measuring grating sensitizing piece is arranged in the temperature measuring cavity, one end of the temperature measuring grating sensitizing piece is fixedly connected with one partition plate, the other end of the temperature measuring grating sensitizing piece penetrates through the other partition plate for suspension arrangement, so that the temperature measuring grating sensitizing piece can freely stretch out and draw back when expanding with heat and contracting with cold, a heat conducting medium is arranged in the temperature measuring cavity, the temperature measuring grating sensitizing piece is immersed in the heat conducting medium, the temperature measuring grating sensitizing piece is connected with a third optical fiber, the third optical fiber is recorded corresponding to the position grating of the temperature measuring grating sensitizing piece, and the grating on the third optical fiber is tightly adhered to the temperature measuring grating sensitizing piece, the grating characteristic values of the first optical fiber and the second optical fiber are the same, the third optical fiber penetrates through the temperature measuring metal shell, the temperature measuring metal shell is connected with the temperature measuring metal wire, and the temperature measuring metal wire penetrates through the framework and extends outwards;

the indirect pressure measuring unit comprises a fourth optical fiber, the fourth optical fiber is arranged along the longitudinal axis of the outer side wall of the male metal sheet, the fourth optical fiber corresponds to a grating recorded in the middle of the male metal sheet, and the grating characteristic values on the fourth optical fiber are the same as those on the first optical fiber, the second optical fiber and the third optical fiber;

the optical cables are formed by four optical fibers with different numbers from two ends of the framework in sequence and connected with the optical fiber connectors of the four channels;

a skin encapsulated outside the carcass and the optical cable, the skin being compatible with hydraulic media material within the conduit; the temperature measuring metal wire penetrates through the framework and the surface skin and then extends outwards.

2. The fish-type fiber grating pressure and temperature sensor as claimed in claim 1, wherein the two metal sheets have gaps at longitudinal ends thereof, the size of the gaps is changed by the deformation of the two metal sheets, and the minimum size of the gaps is not smaller than the diameter size of the optical fiber.

3. The fish-type fiber grating pressure and temperature sensor as claimed in claim 2, wherein the male surface metal sheet is provided with protruding rib grooves, the temperature measuring metal shell is matched with the rib grooves on the inner wall of the male surface metal sheet, and the connecting position of the temperature measuring metal shell and the rib grooves is sealed by a colloid.

4. The fish-type FBG pressure and temperature sensor as claimed in claim 3, wherein the temperature measuring cavity is filled with a heat conducting medium 1/2-4/5, and the heat conducting medium is selected from heat conducting silicone oil or heat conducting silicone grease.

5. The fish-type FBG pressure and temperature sensor as claimed in claim 3 or 4, wherein two connecting rods are respectively disposed at two ends of the cavity in the frame, two ends of each connecting rod are respectively disposed through the female metal sheet and the male metal sheet, an intermediate connecting ring is disposed at a position between the female metal sheet and the male metal sheet, the intermediate connecting ring is connected with a pulling rope, and the pulling rope is connected with the optical fiber connector.

6. The fish-type fiber grating pressure and temperature sensor as claimed in claim 5, wherein two ends of the connecting rod are respectively provided with end connection rings at outer positions of the frames, two end connection rings are connected with torsion resistant ropes, and the torsion resistant ropes are connected with end connection rings of connecting rods of other frames of the fish-type sensor in series or with corresponding holes on fiber connectors at corresponding ends thereof, so as to enhance the connection stability between adjacent frames.

7. The fish-type fiber grating pressure and temperature sensor as claimed in claim 6, wherein each of the metal sheets is provided with at least two side grooves, the side grooves being symmetrically disposed about a longitudinal center axis of the metal sheet such that portions left beside the side grooves form a plurality of supporting portions which are engaged with each other; when the skeleton receives liquid pressure after, two the supporting part that the sheetmetal corresponds can the mutual butt to increase the whole modulus of elasticity of skeleton.

8. The fish-type fiber grating pressure and temperature sensor as claimed in claim 7, wherein the two metal sheets are symmetrically provided with end grooves at both longitudinal ends thereof, the gap is formed between the portions left beside the end grooves, and the intermediate connecting ring can abut against the portions left beside the end grooves of the two metal sheets, so that the minimum dimension of the gap is not smaller than the diameter dimension of the optical fiber.

9. The fish-type fiber bragg grating pressure and temperature sensor according to claim 8, wherein the supporting portion is bent to form a corresponding contact surface between the two corresponding side supporting portions of the metal sheets; 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.

10. The fish-type fiber bragg grating pressure and temperature sensor as claimed in claim 9, wherein the female-side metal piece is provided with through grooves along the upper and lower sides of the optical fiber, so that the female-side metal piece can rapidly deform and respond at low pressure, the first optical fiber is arranged on the outer side of the female-side metal piece, and the second optical fiber is arranged on the inner side of the female-side metal piece; the gratings on the first optical fiber and the second optical fiber are combined together to be suitable for measuring the liquid pressure in the pipeline, and the grating on the third optical fiber is suitable for measuring the liquid temperature in the pipeline; the grating on the fourth optical fiber is suitable for measuring the comprehensive value of the pressure and the temperature of the liquid in the pipeline, the pressure is indirectly measured through the temperature detection value obtained by the grating on the third optical fiber, and the temperature value detected by the grating on the third optical fiber can be checked under the given pressure by combining with the calibration equipment.

Background

The fiber grating is a diffraction grating formed by axially and periodically modulating the refractive index of a fiber core by a certain method, is a passive filter device, and is widely applied to the fields of fiber communication and sensing because the grating fiber has the advantages of small volume, low welding loss, full compatibility with fiber, embedding of intelligent materials and the like, and the resonant wavelength of the grating fiber is sensitive to changes of external environments such as strain, refractive index, concentration and the like.

The common fiber grating has poor tensile and bending resistance under the naked condition, so that the packaging protection of the fiber grating is very necessary. Because the temperature resistance of the fiber grating is poor, if the working temperature is higher than the heat resistance temperature of the fiber grating, the central wavelength of the grating generates large drift, so that the fiber grating is calibrated by linear fitting, and the measuring range is limited.

At present, when the pressure or the temperature in a hydraulic pipeline is detected, a method of forming a detection process hole in the radial direction of the pipeline and installing a pressure or temperature sensor probe on the radial side wall of the pipeline is generally adopted, but the 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. Most of the liquid pressure measurement in the pipeline is carried out by using the fiber grating principle, but when the fiber grating pressure sensor is used for pressure measurement, the problems of small bearing capacity and small measurement pressure range exist. Therefore, the pressure sensor is generally packaged by adopting a cantilever beam amplification principle at present so as to solve the problem of small bearing of the sensor. However, this also causes a problem of increase in the volume of the sensor; and the problem that the range of the measured pressure is small cannot be solved by packaging the sensor, namely the range of the pressure sensor cannot meet the actual requirement of the engineering hydraulic machinery.

The fiber grating temperature sensor has the biggest characteristic that a plurality of sensors can be connected in series to realize distributed temperature measurement, 35 temperature sensors can be connected in series on a single optical fiber at most, wiring quantity is greatly reduced, and the fiber grating temperature sensor is simple, reliable and economical. When an engineering structure of the existing fiber grating temperature sensor is applied, two problems are encountered, namely the problem of the strength of the fiber grating temperature sensor and the problem of time response, and the high strength inevitably causes large thickness of a packaging shell, so that the response speed to the environmental temperature is influenced; to increase the response speed, the thickness of the encapsulating tube is reduced, which in turn causes a reduction in the protective strength. In the prior art, the packaging structure of the fiber grating temperature sensor cannot have strong protection strength and fast response speed at the same time.

The invention (CN 201010141147.4A fiber grating temperature sensor) ensures stronger protection strength to the fiber grating by adopting metal, glass or ceramic material to make the packaging tube for packaging; however, the grating senses the external ambient temperature of the packaging tube mainly by sensing the heat of the enclosed gas in the packaging tube, the grating is easily deformed by the expansion pressure of the internal gas at high temperature, and the internal heat dissipation speed is influenced to cause response delay when the ambient temperature is reduced.

Therefore, a detection system capable of realizing high-precision temperature and pressure distribution in a hydraulic pipe is needed, and is used for high-precision detection of oil temperature in the pipe and acquisition of nondestructive internal pressure data of multipoint pipe walls of the pipe.

Disclosure of Invention

The invention provides a fish-shaped fiber grating pressure and temperature sensor which is reasonable in structural design, a fishbone-shaped metal sheet is designed according to the bionics principle of a fish body, fiber grating sensors are arranged on the inner side and the outer side of the central axis of the metal sheet and play a role of a strain diaphragm at low pressure, two optical fibers are arranged on the two sides of the 'thenar line' of the metal sheet, and 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 invention fully utilizes the characteristics of large-capacity high-speed operation of a computer, overcomes the problem that the detection range cannot be expanded due to information loss caused by a linear fitting method in sensor calibration, thereby expanding the pressure detection range of the conventional fiber grating sensor, solves the problems in the prior art, utilizes the sub-symmetrical structure of a fish body, transmits the temperature to the wall of a temperature-measuring cavity arranged in a framework through a beard-shaped temperature-measuring metal wire protruding to the outer side at the other side, and transmits the temperature to a temperature-measuring grating sensitization part through a partition plate on the wall of the temperature-measuring cavity and heat-conducting silicone oil in the temperature-measuring cavity, and the fiber grating is fixed on the temperature-measuring grating sensitization part, thereby enhancing the timeliness of the fiber grating for collecting the environmental temperature change and also improving the sensitivity coefficient of the temperature signal; meanwhile, the elastic modulus of the partition plate and the wall of the temperature measurement cavity is far larger than the elastic modulus of the surrounding air bag and the elastic body framework, so that the interference of pressure strain outside the fish body on the longitudinal deformation of the grating on the temperature measurement grating sensitization part in the temperature measurement metal shell is greatly relieved, and on the other hand, the longitudinal deformation of the optical fiber adhered to the longitudinal axis of the arc tile-shaped temperature measurement grating sensitization part is not influenced even if the partition plate is slightly deformed due to external stress because the temperature measurement grating sensitization part is fixedly connected with the partition plate, so that the interference of the external pressure on the longitudinal deformation of the grating on the temperature measurement grating sensitization part in the temperature measurement metal shell is avoided, and the cross interference of the deformation caused by the external stress on the longitudinal signal of the optical fiber grating for measuring the temperature is overcome; moreover, only one end of the temperature measurement grating sensitization piece is fixed when longitudinally deforming, and the other end is freely suspended, so that the cross interference of the internal thermal stress deformation caused by thermal expansion and cold contraction to the longitudinal signal of the fiber grating for measuring the temperature is overcome, and the high-precision detection of the fiber grating on the temperature is realized; finally, in order to fully utilize the information acquired by the temperature signals and expand the detection range of the fiber bragg grating groups on the two sides of the female metal sheet on the pressure, the fiber bragg grating on the outer side of the male metal sheet can be used for simultaneously detecting the pressure and the temperature data of the liquid in the pipeline, and the measurement of the fiber bragg grating on the outer side of the male metal sheet on the pressure is realized through the back calculation of the table lookup after the temperature data is acquired.

The technical scheme adopted by the invention for solving the technical problems is as follows: a fish fiber grating pressure and temperature sensor adapted to sense the pressure and temperature of a fluid in a conduit, comprising:

the metal sheet is in a longitudinal long and transverse short sheet structure, and longitudinal grooves are symmetrically formed in one metal sheet along two sides of a longitudinal central axis of the metal sheet and are arranged as a negative metal sheet; the other metal sheet is symmetrically provided with rib grooves protruding outwards along the longitudinal direction along the two sides of the longitudinal central axis of the other metal sheet and is set as a male surface metal sheet; the middle parts of the male metal sheet and the female metal sheet are respectively arranged in an outward protruding mode, so that 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;

the direct pressure measuring unit comprises a first optical fiber and a second optical fiber, the first optical fiber and the second optical fiber are symmetrically arranged along the longitudinal axis of the inner side wall and the outer side wall of the female metal sheet, the first optical fiber and the second optical fiber correspond to the middle of the female metal sheet, gratings are symmetrically recorded, and the grating characteristic values of the first optical fiber and the second optical fiber are the same; when the framework is subjected to liquid pressure in a pipeline, the gratings on the first optical fiber and the second optical fiber are subjected to positive and negative deformation along the longitudinal direction of the framework, so that the pressure detection of temperature self-compensation is realized;

the temperature measuring unit comprises a temperature measuring metal shell arranged in a cavity, the temperature measuring metal shell is connected with the inner wall of a male metal sheet to form a temperature measuring cavity, at least two partition plates connected with the inner wall of the temperature measuring metal shell are arranged in the temperature measuring cavity, a temperature measuring grating sensitizing piece is arranged in the temperature measuring cavity, one end of the temperature measuring grating sensitizing piece is fixedly connected with one partition plate, the other end of the temperature measuring grating sensitizing piece penetrates through the other partition plate for suspension arrangement, so that the temperature measuring grating sensitizing piece can freely stretch out and draw back when expanding with heat and contracting with cold, a heat conducting medium is arranged in the temperature measuring cavity, the temperature measuring grating sensitizing piece is immersed in the heat conducting medium, the temperature measuring grating sensitizing piece is connected with a third optical fiber, the third optical fiber is recorded corresponding to the position grating of the temperature measuring grating sensitizing piece, and the grating on the third optical fiber is tightly adhered to the temperature measuring grating sensitizing piece, the grating characteristic values of the first optical fiber and the second optical fiber are the same, the third optical fiber penetrates through the temperature measuring metal shell, the temperature measuring metal shell is connected with the temperature measuring metal wire, and the temperature measuring metal wire penetrates through the framework and extends outwards;

the indirect pressure measuring unit comprises a fourth optical fiber, the fourth optical fiber is arranged along the longitudinal axis of the outer side wall of the male metal sheet, the fourth optical fiber corresponds to a grating recorded in the middle of the male metal sheet, and the grating characteristic values on the fourth optical fiber are the same as those on the first optical fiber, the second optical fiber and the third optical fiber;

the optical cables are formed by four optical fibers with different numbers from two ends of the framework in sequence and connected with the optical fiber connectors of the four channels;

a skin encapsulated outside the carcass and the optical cable, the skin being compatible with hydraulic media material within the conduit; the temperature measuring metal wire penetrates through the framework and the surface skin and then extends outwards.

Further, the two metal sheets have gaps at two longitudinal end positions, the size of the gap is changed under the influence of the deformation of the two metal sheets, and the minimum size of the gap is not smaller than the diameter size of the optical fiber.

Furthermore, the male surface metal sheet is provided with a convex rib groove, the temperature measurement metal shell is matched with the rib groove on the inner wall of the male surface metal sheet, and the connection position of the temperature measurement metal shell and the rib groove is sealed by a colloid.

Furthermore, the temperature measuring cavity is filled with 1/2-4/5 heat conducting media, and the heat conducting media are heat conducting silicone oil or heat conducting silicone grease.

Further, the both ends of cavity are equipped with two connecting rods respectively in the skeleton, and the both ends of every connecting rod pass negative metal sheet and positive metal sheet setting respectively, the connecting rod is located and is equipped with middle go-between in the position between negative metal sheet and the positive metal sheet, middle go-between and haulage rope link to each other, haulage rope and fiber connector link to each other.

Furthermore, the two ends of the connecting rod are respectively provided with an end connecting ring at the outer side of the framework, the two end connecting rings are connected with the torsion-resistant rope, the torsion-resistant rope is connected with the end connecting rings of the connecting rods of the frameworks of other serially connected fish-type sensors or connected with corresponding holes on the optical fiber connectors at the corresponding ends of the torsion-resistant rope, so that the connection stability between the adjacent frameworks is enhanced.

Furthermore, each metal sheet is provided with at least two side grooves which are symmetrically arranged relative to the longitudinal central axis of the metal sheet, so that the parts left beside the side grooves form a plurality of supporting parts which are matched with each other; when the skeleton receives liquid pressure after, two the supporting part that the sheetmetal corresponds can the mutual butt to increase the whole modulus of elasticity of skeleton.

Furthermore, end grooves are symmetrically arranged at two longitudinal ends of the two metal sheets, the gap is formed between the parts left beside the end grooves, and the middle connecting ring can be mutually abutted with the parts left beside the end grooves of the two metal sheets, so that the minimum size of the gap is not smaller than the diameter size of the optical fiber.

Furthermore, the supporting parts are bent, so that the side supporting parts corresponding to the two metal sheets form corresponding contact surfaces; 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, through grooves are dug in the female surface metal sheet along the upper side and the lower side of the optical fibers, so that the female surface metal sheet can quickly deform and respond under low pressure, the first optical fibers are arranged on the outer side of the female surface metal sheet, and the second optical fibers are arranged on the inner side of the female surface metal sheet; the gratings on the first optical fiber and the second optical fiber are combined together to be suitable for measuring the liquid pressure in the pipeline, and the grating on the third optical fiber is suitable for measuring the liquid temperature in the pipeline; the grating on the fourth optical fiber is suitable for measuring the comprehensive value of the pressure and the temperature of the liquid in the pipeline, the pressure is indirectly measured through the temperature detection of the grating on the third optical fiber, and the temperature value detected by the third optical fiber can be checked in a rechecking mode under the given pressure by combining with the calibration equipment.

The calibration equipment is mainly used for calibrating pressure and temperature; the pressure calibration is mainly to set the pressure step by step within the working pressure range according to the step length required by the precision, collect the difference value of the characteristic center wavelength offset of the grating group on the first optical fiber and the second optical fiber under the set pressure, and establish a one-to-one corresponding table between the pressure and the collected signal (the difference value of the offset); the temperature calibration is mainly to set the temperature step by step according to the step length required by precision within the working temperature range, collect the characteristic center wavelength offset of the grating group on the third optical fiber under the set temperature and establish a one-to-one corresponding table between the temperature and the collected signal (offset); further, setting temperature step by step, boosting step by step within each given temperature, setting pressure step by taking pressure required precision as a step length, acquiring grating characteristic center wavelength offset on the third optical fiber and the fourth optical fiber under the set pressure, establishing grating characteristic center wavelength offset on the fourth optical fiber corresponding to the pressure at each stage under different temperatures, calibrating the grating characteristic center wavelength offset on the fourth optical fiber corresponding to the pressure at each stage under different temperatures in a fishing net-shaped data table formed by the pressure and the temperature, searching temperature signals on the third optical fiber and the grating characteristic center wavelength offset on the fourth optical fiber, and screening through the fishing net-shaped data table to obtain a corresponding pressure value or a pressure value and a precision range of a grid accessory.

The fish-bone-shaped metal sheet has the advantages that the structure is reasonable in design, the fishbone-shaped metal sheet is designed according to the bionics principle of a fish body, the fiber grating sensors are arranged on the inner side and the outer side of the central axis of the metal sheet and play a role of a strain diaphragm when the pressure is low, the two optical fibers are arranged on the two sides of the 'thenar line' of the metal sheet, the temperature influence is eliminated by using the positive and negative deformation principle of the two grating sensors, and therefore the pressure detection of temperature self-compensation is achieved; the invention fully utilizes the characteristics of large-capacity high-speed operation of a computer, overcomes the problem that the detection range cannot be expanded due to information loss caused by a linear fitting method in sensor calibration, thereby expanding the pressure detection range of the conventional fiber grating sensor, solves the problems in the prior art, utilizes the sub-symmetrical structure of a fish body, transmits the temperature to the wall of a temperature-measuring cavity arranged in a framework through a beard-shaped temperature-measuring metal wire protruding to the outer side at the other side, and transmits the temperature to a temperature-measuring grating sensitization part through a partition plate on the wall of the temperature-measuring cavity and heat-conducting silicone oil in the temperature-measuring cavity, and the fiber grating is fixed on the temperature-measuring grating sensitization part, thereby enhancing the timeliness of the fiber grating for collecting the environmental temperature change and also improving the sensitivity coefficient of the temperature signal; meanwhile, the elastic modulus of the partition plate and the wall of the temperature measurement cavity is far larger than the elastic modulus of the surrounding air bag and the elastic body framework, so that the interference of pressure strain outside the fish body on the longitudinal deformation of the grating on the temperature measurement grating sensitization part in the temperature measurement metal shell is greatly relieved, and on the other hand, the longitudinal deformation of the optical fiber adhered to the longitudinal axis of the arc tile-shaped temperature measurement grating sensitization part is not influenced even if the partition plate is slightly deformed due to external stress because the temperature measurement grating sensitization part is fixedly connected with the partition plate, so that the interference of the external pressure on the longitudinal deformation of the grating on the temperature measurement grating sensitization part in the temperature measurement metal shell is avoided, and the cross interference of the deformation caused by the external stress on the longitudinal signal of the optical fiber grating for measuring the temperature is overcome; moreover, only one end of the temperature measurement grating sensitization piece is fixed when longitudinally deforming, and the other end is freely suspended, so that the cross interference of the internal thermal stress deformation caused by thermal expansion and cold contraction to the longitudinal signal of the fiber grating for measuring the temperature is overcome, and the high-precision detection of the fiber grating on the temperature is realized; finally, in order to fully utilize the information acquired by the temperature signals and expand the detection range of the fiber bragg grating groups on the two sides of the female metal sheet on the pressure, the fiber bragg grating on the outer side of the male metal sheet can be used for simultaneously detecting the pressure and the temperature data of the liquid in the pipeline, and the measurement of the fiber bragg grating on the outer side of the male metal sheet on the pressure is realized through the back calculation of the table lookup after the temperature data is acquired.

Drawings

Fig. 1 is a schematic perspective view of a skeleton main body structure according to the present invention.

Fig. 2 is a schematic top view of the skeleton main body structure of the present invention.

Fig. 3 is a side view of the skeleton structure of the present invention.

FIG. 4 is a schematic sectional view of the assembled structure of the present invention.

FIG. 5 is a schematic view of a configuration of a plurality of sensors according to the present invention.

FIG. 6 is a schematic structural diagram of the optimized state of the male-side metal sheet according to the present invention.

FIG. 7 is a schematic structural diagram of the optimized state of the female metal sheet according to the present invention.

In the figure, 1, a female side metal sheet; 2. a rib groove; 3. a male-side metal sheet; 4. a cavity; 5. an air bag; 6. a filler; 7. a first optical fiber; 8. a second optical fiber; 9. measuring the temperature of the metal shell; 10. a temperature measuring cavity; 11. a partition plate; 12. a temperature measurement grating sensitization part; 13. a third optical fiber; 14. measuring the temperature of the metal wire; 15. a fourth optical fiber; 16. an optical fiber connector; 17. a gap; 18. a connecting rod; 1801. a middle connecting ring; 1802. an end connecting ring; 19. a hauling rope; 20. a torsion resistant rope; 21. a lateral groove; 22. a support portion; 23. an end groove; 24. and (4) a groove.

Detailed Description

In order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to 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. 1-7, a fish-type fiber grating pressure and temperature sensor, suitable for detecting the liquid pressure and temperature in the pipeline, comprises a framework, a direct pressure measuring unit, a temperature measuring unit, an indirect pressure measuring unit and a skin, wherein the framework is composed of two metal sheets which are symmetrically arranged, the metal sheets are arranged in a longitudinal long and transverse short sheet structure, one of the metal sheets is symmetrically provided with longitudinal grooves along the two sides of the longitudinal central axis thereof, and is arranged as a female metal sheet 1; the other metal sheet is symmetrically provided with rib grooves 2 protruding outwards along the longitudinal direction along the two sides of the longitudinal central axis of the other metal sheet, and the rib grooves are arranged as male surface metal sheets 3; the middle parts of the male metal sheet 3 and the female metal sheet 1 are respectively arranged to bulge outwards, so that a cavity 4 is formed between the two metal sheets, an air bag 5 similar to a fish bubble is arranged in the cavity 4, and a filler 6 is arranged between the air bag 5 and the metal sheets; the air bag 5 is internally provided with inert gas or other nontoxic gas, and the filler 6 is elastic filler which comprises rubber or resin.

The direct pressure measuring unit comprises a first optical fiber 7 and a second optical fiber 8, the first optical fiber 7 and the second optical fiber 8 are symmetrically arranged along the longitudinal axis of the inner side wall and the outer side wall of the female metal sheet 1, the first optical fiber 7 and the second optical fiber 8 are symmetrically recorded with gratings corresponding to the middle of the female metal sheet 1, and the grating characteristic values on the first optical fiber 7 and the second optical fiber 8 are the same (grating grid period is the same, recording depth is the same, and grid length is the same); when the framework is subjected to liquid pressure in a pipeline, the gratings of the first optical fiber 7 and the second optical fiber 8 are deformed in a positive and negative mode along the longitudinal direction of the framework, the working principle of eliminating temperature influence is similar to that of a spring tube type fiber grating pressure sensor, and pressure detection of temperature self-compensation is realized;

the temperature measuring unit comprises a temperature measuring metal shell 9 arranged in a cavity 4, the temperature measuring metal shell 9 is connected with the inner wall of a male metal sheet 3 to form a temperature measuring cavity 10, at least two clapboards 11 connected with the inner wall of the temperature measuring metal shell 9 are arranged in the temperature measuring cavity 10, a temperature measuring grating sensitizing piece 12 is arranged in the temperature measuring cavity 10, one end of the temperature measuring grating sensitizing piece 12 is fixedly connected with one of the clapboards 11, the other end of the temperature measuring grating sensitizing piece 12 penetrates through the other clapboard 11 for arrangement, so that the temperature measuring grating sensitizing piece 12 can freely stretch out and draw back at the suspension end due to thermal expansion and cold contraction, the clapboards 11 are arranged at intervals along the longitudinal axis of the temperature measuring cavity 10, holes or holes are formed in the middle part of the clapboard 11, the weight is ensured to be light, the supporting strength is good, a heat-conducting medium is arranged in the temperature measuring cavity 10, the temperature measuring grating piece 12 is immersed in the heat-conducting medium, the temperature measuring grating sensitizing piece 12 is connected with a third optical fiber 13, and the third optical fiber 13 corresponds to the position grating of the recording piece 12, the grating of the third optical fiber 13 is tightly adhered to the temperature-measuring grating sensitization part 12 and has the same characteristic value as the grating on the first optical fiber 7 and the second optical fiber 8, the third optical fiber 13 penetrates through the temperature-measuring metal shell 9, the temperature-measuring metal shell 9 is connected with the temperature-measuring metal wire 14, and the temperature-measuring metal wire 14 penetrates through the framework and extends outwards;

the baffle 11 links to each other with temperature measurement metal-back 9, can be more reliably with the heat of temperature measurement wire 14 through temperature measurement metal-back 9, baffle 11 conduction to temperature measurement grating sensitization piece 12, other parts of temperature measurement grating sensitization piece 12 can be suspension or swing joint on other baffles 11, in order to guarantee that temperature measurement grating sensitization piece 12 receives the temperature influence and takes place the flexible deformation of freedom, temperature measurement grating sensitization piece 12 can receive the heat of heat-conducting medium and baffle 11 transmission simultaneously, baffle 11 can also play the effect of auxiliary stay to temperature measurement grating sensitization piece 12, make temperature measurement grating sensitization piece 12 keep the gesture stable, avoid external fluid flow to influence No. three optic fibre 13 after producing the disturbance to the sensor and rock and influence the detection precision of temperature measurement. The whole sensor is used for measuring the neural perception principle of the fish on the liquid pressure and temperature, the fish body structure in water is combined, a fishbone-shaped metal sheet is designed, fiber grating sensors are arranged on the inner side and the outer side of the central axis of the metal sheet, the fiber grating sensors play a role of a strain diaphragm at low pressure, two optical fibers and fiber gratings which are symmetrically arranged inside and outside are arranged on the two sides of the longitudinal axis of the metal sheet (the thenar line), and the temperature influence is eliminated by utilizing the positive and negative deformation principle of the two optical gratings, so that the pressure detection of temperature self-compensation is realized; the characteristic of large-capacity high-speed operation of a computer is fully utilized, the problem that the detection range cannot be expanded due to information loss caused by a linear fitting method in sensor calibration is solved, the range of the detection pressure of the conventional fiber grating sensor is expanded, the problems in the prior art are solved, a sub-symmetrical structure of a fish body is utilized, the temperature is transmitted to a temperature-measuring metal shell 9 arranged in a framework through a beard-shaped temperature-measuring metal wire 14 protruding to the outer side at the other side, then the temperature is transmitted to a temperature-measuring grating sensitization part 12 through a partition plate 11 on the temperature-measuring metal shell 9 and heat-conducting silicon oil in a temperature-measuring cavity, and the fiber grating is fixed on the temperature-measuring grating sensitization part 12, so that the timeliness of collecting the fiber grating for environment temperature change is enhanced, and the sensitivity coefficient for temperature signals is also improved; meanwhile, because the elastic modulus of the partition plate 11 and the wall of the temperature measurement cavity 10 is far greater than that of the surrounding air bag and the elastic modulus of the elastic body skeleton, the interference of pressure strain outside the fish body on the longitudinal deformation of the grating on the temperature measurement grating sensitizing piece 12 in the temperature measurement metal shell 9 is greatly relieved, and on the other hand, because only one arc-shaped cross section of the temperature measurement grating sensitizing piece 12 is fixedly connected with the partition plate 11, even if the partition plate has small deformation due to external stress, the longitudinal deformation of the optical fiber pasted on the longitudinal axis of the arc tile-shaped temperature measurement grating sensitizing piece 12 is not influenced, so that the interference of the external pressure on the longitudinal deformation of the grating on the temperature measurement grating sensitizing piece 12 in the temperature measurement metal shell 9 is avoided, and the cross interference of the deformation caused by the external stress on the longitudinal signal of the optical fiber grating for measuring the temperature is overcome; moreover, because only one end of the temperature measurement grating sensitization piece 12 is fixed when longitudinally deforming, and the other end is freely suspended, the cross interference of the internal thermal stress deformation caused by thermal expansion and cold contraction to the longitudinal signal of the fiber grating for measuring the temperature is overcome, thereby the high-precision detection of the fiber grating for the temperature is realized; finally, in order to fully utilize the information acquired by the temperature signals and expand the detection range of the fiber bragg grating groups on the two sides of the female metal sheet 1 to the pressure, the fiber bragg grating on the outer side of the male metal sheet 3 can be used for simultaneously detecting the pressure and the temperature data of the liquid in the pipeline, and the measurement of the fiber bragg grating on the outer side of the male metal sheet 3 to the pressure is realized through the back calculation of the table lookup after the temperature data is acquired.

The indirect pressure measuring unit comprises a fourth optical fiber 15, the fourth optical fiber 15 is arranged along the longitudinal axis of the outer side wall of the male metal sheet 3, the fourth optical fiber 15 is corresponding to a grating recorded in the middle of the male metal sheet 3, and the grating on the fourth optical fiber 15 has the same characteristic value as the grating on the first optical fiber 7, the second optical fiber 8 and the third optical fiber 13;

the optical fibers with different numbers are sequentially combined into optical cables from two ends of the framework, and the optical cables are connected with the optical fiber connectors 16 of the four channels;

the surface skin is encapsulated outside the framework and the optical cable, and the surface skin is compatible with the hydraulic medium material in the pipeline; the temperature measuring metal wire 14 passes through the framework and the surface skin and extends outwards.

It should be noted that, the two metal sheets have gaps 17 at both longitudinal end positions, the size of the gap 17 changes under the influence of the deformation of the two metal sheets, and the minimum size of the gap 17 is not smaller than the diameter size of the optical fiber.

In the preferred embodiment, the male surface metal sheet 3 is provided with a convex rib groove 2, the temperature measuring metal shell 9 is matched with the rib groove 2 on the inner wall of the male surface metal sheet 3, and the connecting position of the temperature measuring metal shell 9 and the rib groove 2 is sealed by colloid.

In a preferred embodiment, the temperature measuring cavity 10 is filled with a heat conducting medium 1/2-4/5, and the heat conducting medium is heat conducting silicone oil or heat conducting silicone grease. The heat-conducting medium is not filled, and the capacity of the heating medium is controlled to be in the range of 1/2-4/5, on the premise of ensuring the heat-conducting capacity, the deformation factor of the outer wall of the temperature measuring cavity 10 is considered, so as to absorb the influence of strain. The volume of the heat-conducting medium can be increased by 10% after the heat-conducting medium is heated from 20 ℃ to 200 ℃, so that the heat-conducting medium filled in the temperature measuring cavity 10 can be filled in 4/5 of the volume of the temperature measuring cavity 10 at most, and the heat-conducting medium in the temperature measuring cavity 10 is ensured not to extrude the cavity wall of the temperature measuring cavity 10 after being heated and expanded.

In a preferred embodiment, two connecting rods 18 are respectively arranged at two ends of the cavity 4 in the framework, two ends of each connecting rod 18 are respectively arranged by penetrating through the female metal sheet 1 and the male metal sheet 3, an intermediate connecting ring 1801 is arranged at a position of the connecting rod 18 between the female metal sheet 1 and the male metal sheet 3, the intermediate connecting ring 1801 is connected with a pulling rope 19, and the pulling rope 19 is connected with the optical fiber connector 16; the length of the pull-cord 19 may be more than ten times the longitudinal length of the frame, thereby avoiding the effect of rear turbulence of upstream objects on the pressure sensing of one sensor.

In the preferred embodiment, the two ends of the connecting rod 18 are respectively provided with end connection rings 1802 at the outer side positions of the frames, the two end connection rings 1802 are connected with torsion cords 20, and the torsion cords 20 are connected with the end connection rings 1802 of the connecting rods 18 of other frames of the serial fish-type sensor or connected with corresponding holes on the optical fiber connectors 16 at the corresponding ends thereof, so as to enhance the connection stability between the adjacent frames.

In a preferred embodiment, each metal sheet is provided with at least two side grooves 21, the side grooves 21 being symmetrically arranged about a longitudinal center axis of the metal sheet such that portions left beside the side grooves 21 form a plurality of support portions 22 which are engaged with each other; when the frame is under liquid pressure, the supporting portions 22 corresponding to the two metal sheets can be abutted to each other to increase the overall elastic modulus of the frame.

In the preferred embodiment, the two metal sheets are symmetrically provided with end grooves 23 at both longitudinal ends, a gap 17 is formed between the parts left beside the end grooves 23, and the intermediate connecting ring 18 can abut against the parts left beside the end grooves 23 of the two metal sheets, so that the minimum size of the gap 17 is not smaller than the diameter size of the optical fiber. As shown in the attached drawing 3, the two end positions of the metal sheet are provided with notches compared with other positions, after the whole sensor is subjected to external oil pressure, when the main body parts of the metal sheet are mutually abutted, the notches at the two ends can ensure that the size of the gap 17 is larger than the diameter of the optical fiber, the two end positions of the metal sheet can not be in mutual contact with the extruded optical fiber, and the safety of the optical fiber is protected.

In a preferred embodiment, the supporting portion 22 is bent to form a corresponding contact surface between the two corresponding side supporting portions 22 of the metal sheets; when the frame is pressed, the corresponding support parts abut against each other, or the filler 6 is provided between the support parts, so that the support parts 22 and the filler 6 abut against each other.

It is worth mentioning that through grooves 24 are dug along the upper side and the lower side of the optical fiber on the female metal sheet 1, so that the female metal sheet 1 can quickly deform and respond under low pressure, the first optical fiber 7 is arranged on the outer side of the female metal sheet 1, and the second optical fiber 8 is arranged on the inner side of the female metal sheet; the gratings on the first optical fiber 7 and the second optical fiber 8 are combined together to be suitable for measuring the pressure of liquid in the pipeline, and the grating on the third optical fiber 13 is suitable for measuring the temperature of the liquid in the pipeline; the grating on the fourth optical fiber 15 is suitable for measuring the comprehensive value of the pressure and the temperature of the liquid in the pipeline, and the pressure is indirectly measured through the temperature detection of the grating on the third optical fiber 13; in addition, the calibration equipment can also perform a double check and check on the temperature value detected by the grating on the third optical fiber 13 under a given pressure.

Calibration equipment, mainly calibrating pressure and temperature; the pressure calibration is mainly to set the pressure step by step within the working pressure range according to the step length required by the precision, collect the difference value of the characteristic center wavelength offset of the grating group on the first optical fiber 7 and the second optical fiber 8 under the set pressure, and establish a one-to-one corresponding table between the pressure and the collected signal (the difference value of the offset); the temperature calibration is mainly to set the temperature step by step according to the step length required by precision within the working temperature range, collect the characteristic center wavelength offset of the grating group on the third optical fiber 13 under the set temperature, and establish a one-to-one corresponding table between the temperature and the collected signal (offset); further, setting temperature step by step, boosting step by step within each given temperature, setting pressure step by taking pressure required precision as a step length, collecting grating characteristic center wavelength offset on the third optical fiber 13 and the fourth optical fiber 15 under the set pressure, establishing grating characteristic center wavelength offset on the fourth optical fiber 15 corresponding to each level of pressure under different temperatures, calibrating the grating characteristic center wavelength offset on the pressure and the temperature to form a fishing net-shaped data table, searching a temperature signal on the third optical fiber 13 and the grating characteristic center wavelength offset on the fourth optical fiber, and screening through the fishing net-shaped data table to obtain a corresponding pressure value or a pressure value and a precision range of a grid accessory.

During the use, as shown in figure 5, through the mutual series connection setting of optic fibre between a plurality of skeletons, make a plurality of sensors form the composite state and use, the grating in the outside is connected, and inboard grating connection is inboard, and the grating of homonymy is guaranteed to be in groups, and fiber connector sign is clear, the order law.

The above-described embodiments should not be construed as limiting the scope of the invention, and any alternative modifications or alterations to the embodiments of the present invention will be apparent to those skilled in the art.

The present invention is not described in detail, but is known to those skilled in the art.