Fiber grating liquid pressure measuring device and method

Abstract

The application discloses a kind of liquid pressure measuring device and method of fiber grating, it is related to liquid pressure sensor technical field, including shell, first fiber grating component and second fiber grating component;First fiber grating component includes first isolation component, first force transmission component, first beam elastomer, first fiber grating sensor and second fiber grating sensor;First isolation component and second isolation component form liquid-containing cavity between;First force transmission component is arranged on the end face of first isolation component away from liquid-containing cavity;The end face of first force transmission component away from first isolation component is adjacent to the end face of first beam elastomer;First fiber grating sensor and second fiber grating sensor are symmetrically arranged on the two end faces of first beam elastomer;Second fiber grating component is same with the structure of first fiber grating component.The application achieves the effect that pressure measurement precision is high, anti-electromagnetic interference is strong and stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid pressure sensor, in particular to a kind of fiber grating liquid pressure measuring device and method. BACKGROUND

[0002] Liquid pressure is the main parameter reflecting the working condition of hydraulic pipeline, which is related to the function of the entire hydraulic system. In a certain project, real-time monitoring of the working pressure of the test bench hydraulic system is required, which is carried out under the condition of test environment temperature (25±10)℃, working medium is aviation hydraulic oil, the working pressure range of the hydraulic system is 0-28MPa, and the temperature of the allowable working medium is 10℃ higher than the ambient temperature.

[0003] At present, the pressure measurement of hydraulic pipeline mainly uses mechanical and electrical pressure sensors. Mechanical pressure sensors are usually based on mechanical structural parts, but the measurement point is single and cannot transmit data in real time, so it cannot realize long-term real-time monitoring of the pressure of hydraulic pipeline. Electrical pressure sensors generally use resistance, capacitance and other pressure sensitive elements, but the output of such pressure sensors is usually voltage and current signals, which are easily affected by electromagnetic interference, which will affect the pressure measurement accuracy. Moreover, in the harsh working environment of monitoring oil pipeline hydraulic pressure, there is a great safety risk. In the field of fiber grating liquid pressure transmission, there are many different types of products. Common fiber grating liquid pressure monitoring methods include polymer encapsulated fiber grating pressure sensor, elastic sheet encapsulated fiber grating pressure sensor and thin-walled cylinder encapsulated fiber grating pressure sensor.

[0004] (1) Polymer encapsulated fiber grating pressure sensor: usually encapsulates the fiber grating in a thick-walled round tube with polymer, which uses the driving effect of the polymer base to drive the deformation of the fiber grating to improve the pressure sensitivity of the fiber grating. Among them, the fiber grating is encapsulated in an organic polymer base, and the encapsulation technology changes the relative size of the pressure and temperature sensitivity of the fiber grating, and the sensitivity of the fiber grating to pressure is improved. However, the fiber grating pressure sensor has temperature cross-sensitivity problem, and the change of external temperature will have a certain influence on the measurement of pressure, but the fiber grating is easily affected by the cross coupling of strain and temperature, so temperature compensation must be carried out during pressure measurement.

[0005] (2) Elastic sheet encapsulated fiber Bragg grating pressure sensor: the fiber Bragg grating is encapsulated in the cavity of cylinder, and the deformation caused by the pressure response is directly converted into the axial strain of fiber Bragg grating through a plane circular sheet, so that the high sensitivity pressure signal detection is realized. Because the FBG (Fiber Bragg Grating) is subjected to stretching and the photoelastic effect of itself, the change of the center reflection wavelength of FBG is converted again, so that the high sensitivity signal detection is realized. Since the fiber Bragg grating is encapsulated in the cavity of cylinder, the temperature inside the cavity changes slowly when the environment changes. The influence of temperature change on the sensor is mainly through the thermal effect, causing the linear expansion of the cylindrical shell, so as to change the physical length and modulation period of the fiber Bragg grating, causing the drift of the center wavelength, and the temperature change will have a certain influence on the measurement of pressure.

[0006] (3) Thin-walled cylinder encapsulated fiber Bragg grating pressure sensor: the fiber Bragg grating is pasted in the V-shaped groove in the middle of the thin-walled cavity in the radial direction, the strain cylinder will be strained in the axial and radial directions when subjected to pressure, the axial strain drives the deformation of the fiber Bragg grating, and the pressure signal detection is realized. Among them, the strain cylinder will be strained in the axial and radial directions when subjected to pressure, in order to make the grating and the pressure measuring tube closely combined, and at the same time avoid the problem of increasing the thickness of the sensing section cylinder caused by directly grooving on the outer wall of the cylinder. A V-shaped fixed groove is processed on the wall of the pressure measuring tube. When the sensor is encapsulated, the strain grating is pasted in the V-shaped groove in the middle of the thin-walled cavity in the radial direction, and the temperature compensation grating is pasted at the thick wall at the tail end of the sensor. However, the wavelength change of the fiber Bragg grating is jointly restricted by the deformation of the passive temperature compensation sleeve composed of two kinds of materials, different materials have different thermal expansion coefficients, so the uncertainty error of this structure is large, and the sensitivity is not high enough. SUMMARY

[0007] The purpose of the present application is to provide a kind of fiber Bragg grating liquid pressure measuring device and method, reach high pressure measurement precision, strong anti-electromagnetic interference and stable effect.

[0008] To achieve the above object, the present application provides the following scheme:

[0009] A kind of fiber Bragg grating liquid pressure measuring device, including shell, first fiber Bragg grating component and second fiber Bragg grating component;The first fiber Bragg grating component and the second fiber Bragg grating component are all arranged in the shell;

[0010] The first fiber Bragg grating component includes first isolation component, first force transmission component, first beam elastomer, first fiber Bragg grating sensor and second fiber Bragg grating sensor;The second fiber Bragg grating component includes second isolation component, second force transmission component, second beam elastomer, third fiber Bragg grating sensor and fourth fiber Bragg grating sensor;

[0011] The first isolation component and the second isolation component form a liquid containing cavity; the first force transmission component is arranged on the end face of the first isolation component away from the liquid containing cavity; the end face of the first force transmission component away from the first isolation component is adjacent to the end face of the first leontiev elastic body; the first fiber grating sensor and the second fiber grating sensor are symmetrically arranged on the two end faces of the first leontiev elastic body, and the second fiber grating sensor is located on the same side of the first leontiev elastic body as the first force transmission component;

[0012] The second fiber grating component and the first fiber grating component have the same structure;

[0013] In operation, the liquid containing cavity contains a to-be-measured liquid, under the pressure of the to-be-measured liquid, the first isolation component drives the first force transmission component to move towards the first leontiev elastic body, and at the same time, the second isolation component drives the second force transmission component to move towards the second leontiev elastic body; the first force transmission component applies a force to the first leontiev elastic body, so that the first leontiev elastic body deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; the second force transmission component applies a force to the second leontiev elastic body, so that the second leontiev elastic body deforms and drives the third fiber grating sensor and the fourth fiber grating sensor to deform.

[0014] Optionally, the first force transmission component comprises a first wedge-shaped body and a first hemispherical body;

[0015] The first wedge-shaped body is arranged on the end face of the first isolation component away from the liquid containing cavity; the first hemispherical body is arranged on the end face of the first wedge-shaped body away from the first isolation component, and the arc surface of the first hemispherical body is adjacent to the end face of the first leontiev elastic body.

[0016] Optionally, the first leontiev elastic body comprises a fixed end and a free end;

[0017] The fixed end is fixedly arranged on the shell, and the free end is adjacent to the arc surface of the first hemispherical body;

[0018] When not subjected to the force applied by the first hemispherical body, the plane where the fixed end and the free end are located is perpendicular to the surface of the shell; when subjected to the force applied by the first hemispherical body, the free end moves.

[0019] Optionally, the first fiber grating component further comprises a first limiting block, a second limiting block and a third limiting block;

[0020] The first limiting block is arranged on the side of the first Bernoulli elastic body away from the first force transmission assembly, and is used for limiting the moving distance of the free end of the first Bernoulli elastic body.

[0021] The second limiting block and the third limiting block are arranged in the liquid containing cavity, the second limiting block and the third limiting block are located on the same plane, and the plane where the second limiting block and the third limiting block are located is parallel to the end surface of the first isolation component; the second limiting block and the third limiting block are used for limiting the movement of the first isolation component to the liquid containing cavity.

[0022] Optionally, a threaded damping hole is arranged on the shell; the threaded damping hole is used for injecting the to-be-measured liquid into the liquid containing cavity.

[0023] Optionally, the first fiber grating assembly further comprises a first sealing end cover.

[0024] The first sealing end cover is arranged on the side of the first Bernoulli elastic body away from the first force transmission assembly.

[0025] To achieve the above purpose, the application further provides the following technical solutions.

[0026] A fiber grating liquid pressure measurement method applied to a fiber grating liquid pressure measurement device, the method comprising:

[0027] Obtaining the force load sensitivity on the first Bernoulli elastic body and the cross-sectional area of the first isolation component;

[0028] After the to-be-measured liquid is contained in the liquid containing cavity, obtaining the total wavelength drift of the first fiber grating sensor, the total wavelength drift of the second fiber grating sensor, the total wavelength drift of the third fiber grating sensor and the total wavelength drift of the fourth fiber grating sensor;

[0029] According to the total wavelength drift of the first fiber grating sensor, the total wavelength drift of the second fiber grating sensor, the total wavelength drift of the third fiber grating sensor, the total wavelength drift of the fourth fiber grating sensor and the force load sensitivity on the first Bernoulli elastic body, a first acting force is calculated; the first acting force is the acting force applied on the first Bernoulli elastic body under the pressure of the to-be-measured liquid in the liquid containing cavity;

[0030] According to the first acting force and the cross-sectional area of the first isolation component, a liquid pressure value is calculated; the liquid pressure value is the pressure value of the to-be-measured liquid in the liquid containing cavity.

[0031] According to the specific embodiments provided by the application, the following technical effects are disclosed.

[0032] The application discloses a kind of liquid pressure measuring device and method of fiber grating, form liquid-containing cavity between first isolation component and second isolation component, liquid-containing cavity contains liquid to be measured, so that liquid to be measured medium and fiber grating are completely isolated, avoid fiber grating in high pressure, high temperature, strong corrosion The harsh working environment is conducive to improving the working stability and service life of sensor.Under the pressure of liquid to be measured, first isolation component drives first force transmission assembly, moves to the direction of first leibniz elastomer, while second isolation component drives second force transmission assembly, moves to the direction of second leibniz elastomer;First force transmission assembly exerts force on first leibniz elastomer, so that first leibniz elastomer is deformed, and drive first fiber grating sensor and the second fiber grating sensor are deformed;Second force transmission assembly exerts force on second leibniz elastomer, so that second leibniz elastomer is deformed, and drive third fiber grating sensor and fourth fiber grating sensor are deformed;That is, the application combines fiber grating and special pressure conversion structure, converts liquid pressure into fiber grating wavelength change, with high pressure measurement precision, strong electromagnetic interference characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0034] Figure 1 It is a structural schematic diagram of the liquid pressure measuring device of fiber grating of the present application.

[0035] Figure 2 It is a flowchart of the liquid pressure measuring method of fiber grating of the present application. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] In order to overcome the influence of external electromagnetic interference on pressure measurement, and at the same time meet the demand of wide range and high precision pressure monitoring, the research on a liquid pressure transmitting device with wide monitoring range and high precision is extremely important in the field of pressure monitoring of hydraulic pipeline. Based on this, the application provides a kind of liquid pressure measuring device and method based on fiber grating, which solves the problems of liquid pressure monitoring, wide monitoring range, high precision, anti-electromagnetic interference and the like.

[0038] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0039] As shown in Figure 1 The application provides a kind of liquid pressure measuring device based on fiber grating, the device includes a shell, a first fiber grating assembly and a second fiber grating assembly;The first fiber grating assembly and the second fiber grating assembly are both arranged in the shell.

[0040] The first fiber grating assembly includes a first isolation component, a first force transmission assembly, a first beam elastic body BE1, a first fiber grating sensor FBG1 and a second fiber grating sensor FBG2;The second fiber grating assembly includes a second isolation component, a second force transmission assembly, a second beam elastic body BE2, a third fiber grating sensor FBG3 and a fourth fiber grating sensor FBG4. The specific internal structure of the second fiber grating assembly is the same as that of the first fiber grating assembly.

[0041] The first isolation component and the second isolation component form a liquid containing cavity VC1;The first force transmission assembly is arranged on the end face of the first isolation component away from the liquid containing cavity VC1;The end face of the first force transmission assembly away from the first isolation component is adjacent to the end face of the first beam elastic body BE1;The first fiber grating sensor FBG1 and the second fiber grating sensor FBG2 are symmetrically arranged on the two end faces of the first beam elastic body BE1, and the second fiber grating sensor FBG1 and the first force transmission assembly are located on the same side of the first beam elastic body BE1. The above-mentioned fiber grating sensors FBG1, FBG2 are symmetrically fixed on the beam elastic body BE1, which not only can double the load sensitivity, but also can offset the measurement error caused by the temperature influence on the fiber grating FBG1, FBG2. The same is true for the second fiber grating assembly.

[0042] In one specific embodiment, the first isolation component and the second isolation component are both micro pistons, corresponding Figure 1The micro piston MP1 and the micro piston MP2 in the first fiber Bragg grating sensor FBG1 and the second fiber Bragg grating sensor FBG2 are used to isolate the liquid to be measured from the force transmission assembly, the beam elastic body and the fiber Bragg grating sensor, avoid the fiber Bragg grating from being in a harsh working environment of high pressure, high temperature and strong corrosion, and be beneficial to improving the working stability and service life of the sensor.

[0043] The shell is provided with a threaded damping hole DH1; the threaded damping hole DH1 is used for injecting the liquid to be measured into the liquid containing cavity VCl. The liquid injected into the liquid containing cavity VCl is communicated with the threaded damping hole DH1 under the action of the liquid pressure, so that the liquid pressure P2 of the liquid containing cavity VCl and the liquid pressure value P1 to be measured are maintained to be the same (i.e. P2=P1).

[0044] The first force transmission assembly comprises a first wedge-shaped body and a first hemispherical body, wherein the first wedge-shaped body is a first wedge-shaped steel body WS1, and the first hemispherical body is a first hemispherical steel body HE1; the first wedge-shaped body is arranged on the end face of the first isolation component away from the liquid containing cavity; the first hemispherical body is arranged on the end face of the first wedge-shaped body away from the first isolation component, and the arc surface of the first hemispherical body is adjacent to the end face of the first beam elastic body. The second wedge-shaped steel body WS2 and the second hemispherical steel body HE2 in the second fiber Bragg grating assembly are the same.

[0045] The first beam elastic body BE1 comprises a fixed end BE11 and a free end BE12; the fixed end BE11 is fixedly arranged on the shell, and the free end BE12 is adjacent to the arc surface of the first hemispherical body; when not subjected to the action force applied by the first hemispherical body, the plane where the fixed end BE11 and the free end BE12 are located is perpendicular to the surface of the shell; when subjected to the action force applied by the first hemispherical body, the free end BE12 moves. Further, the fixed end is the lower end, and the free end is the upper end.

[0046] In addition, since the first fiber Bragg grating sensor FBG1 and the second fiber Bragg grating sensor FBG2 are fixed on the first beam elastic body BE1, the third fiber Bragg grating sensor FBG3 and the fourth fiber Bragg grating sensor FBG4 are fixed on the second beam elastic body BE2, the deformation of the fiber Bragg grating sensors FBG1, FBG2, FBG3 and FBG4 is determined by the beam elastic bodies BE1 and BE2, and the deformation size of the beam elastic bodies BE1 and BE2 can be changed by adjusting the physical size of the beam elastic body. Therefore, the fiber Bragg grating sensors FBG1, FBG2, FBG3 and FBG4 can adapt to a wide range of pressure detection by adjusting the physical size of the beam elastic body. The liquid pressure conversion element adopts the fiber Bragg grating sensor, so that the pressure measuring device has the characteristics of good anti-electromagnetic interference.

[0047] Preferably, the lengths of the fiber grating sensors FBG1, FBG2 are less than the length of the first beam-shaped elastic body BE1, so that the force transmission assembly, when in contact with the first beam-shaped elastic body BE1, does not squeeze the fiber grating sensors FBG1, FBG2, and does not affect the measurement data of the fiber grating sensors FBG1, FBG2.

[0048] In one specific embodiment, after the to-be-measured liquid fills the liquid container cavity VC1, the micro piston MP1 moves towards the beam-shaped elastic body BE1 under the action of the liquid pressure P2 of the liquid container cavity VC1; since the wedge-shaped steel body WS1 is fixedly connected to the micro piston MP1, and the hemispherical steel body HE1 is fixedly connected to the wedge-shaped steel body WS1, the hemispherical steel body HE1, the wedge-shaped steel body WS1 and the micro piston MP1 move in the same direction; when the hemispherical steel body HE1 contacts the beam-shaped elastic body BE1, an action force F 21 is applied to the free end BE12 of the beam-shaped elastic body BE1 under the action of the liquid pressure P2 of the liquid container cavity VC1. 21 The calculation formula is:

[0049]

[0050] wherein S MP1 is the cross-sectional area of the micro piston MP1. Under the action of the action force F 21 , the beam-shaped elastic body BE1 deforms, and the fiber grating sensors FBG1, FBG2 deform accordingly. Since the fiber grating sensors FBG1, FBG2 are symmetrically fixed on the beam-shaped elastic body BE1, under the action of the action force F 21 , the fiber grating sensor FBG1 is compressed, and the FBG2 is stretched, so that the grating wavelengths of the fiber grating sensors FBG1, FBG2 change as shown in the following formula:

[0051] Δλ FBG1 = -k F21 F 21 + k T ΔT

[0052] Δλ FBG2 = k F21 F 21 + k T ΔT

[0053] wherein Δλ FBG1 , Δλ FBG2 represent the total wavelength drift of the fiber grating sensors FBG1, FBG2 caused by deformation and temperature change, k F21 is the force load sensitivity of the fiber grating sensors FBG1, FBG2 fixed on the beam-shaped elastic body BE1; and k TThe temperature sensitivity of the fiber grating sensors FBG1 and FBG2 represents the wavelength drift caused by the temperature change of the fiber grating sensors FBG1 and FBG2; ΔT is the working temperature change of the fiber grating sensors FBG1 and FBG2, representing the wavelength drift caused by the temperature change of the fiber grating sensors FBG1 and FBG2; the "-" sign represents that FBG1 is compressed, and the "+" sign represents that FBG2 is stretched, because the fiber grating sensors FBG1 and FBG2 are the same type of sensors and are symmetrically fixed on the beam-shaped elastic body BE1, the force load sensitivity and the temperature sensitivity are the same. The difference between the center wavelengths of the two fiber grating sensors FBG1 and FBG2 and the load force are related as follows:

[0054] Δλ FBG2 -Δλ FBG1 =2k F21 F 21 ;

[0055] Wherein, Δλ FBG1 and Δλ FBG2 can be measured by a grating demodulator, and then the difference between the center wavelengths of the fiber grating sensors FBG1 and FBG2 and F 21 can be calculated.

[0056] Similarly, in the second fiber grating assembly, under the action of the liquid pressure P2 of the liquid chamber VC1, an action force F 22 is applied to the beam-shaped elastic body BE2, and the calculation formula of F 22 is as follows:

[0057]

[0058] Wherein, S MP2 is the cross-sectional area of the micro piston MP2; the micro pistons MP1 and MP2 are of the same material and physical size, so the cross-sectional areas of MP1 and MP2 are the same, that is, S MP2 =S MP1 , and therefore the pressures received by BE2 and BE1 are the same, that is, F 22 =F 21 .

[0059] The wavelength changes Δλ FBG3 and Δλ FBG4 of the fiber grating sensors FBG3 and FBG4 are measured by a grating demodulator, and the difference between the center wavelengths of the two fiber grating sensors FBG3 and FBG4 and the load force are related as shown in the following formula:

[0060] Δλ FBG3 -Δλ FBG4 =2k F22 F 22 ;

[0061] Wherein, k F22 is the force load sensitivity of the fiber grating sensor FBG3, FBG4 fixed on the beam elastic body BE2, under the action of force F 22 , the fiber grating sensor FBG3 is stretched, and the fiber grating sensor FBG4 is compressed.

[0062] Since the beam elastic bodies BE1, BE2 are made of the same material and have the same physical size, and the fiber grating sensors FBG1, FBG2, FBG3, FBG4 are of the same model, the force load sensitivity k F22 of the beam elastic body BE2 is the same as the force load sensitivity k F11 of the beam elastic body BE1, that is, k F22 =k F11 ; and since the pressures on BE2 and BE1 are the same, that is, F 22 =F 21 , it can be deduced that:

[0063] Δλ FBG2 -Δλ FBG1 +Δλ FBG3 -Δλ FBG4 =4k F21 F 21 .

[0064] According to the above formula, F 21 can be obtained, and the liquid pressure P2 of the liquid cavity VC1 can be obtained by P2=F 21 ×S MP1 . Since the liquid pressure P2 of the liquid cavity VC1 is the same as the to-be-measured liquid pressure P1, that is, P2=P1, the to-be-measured liquid pressure P1 can be obtained. The symmetrical fixing structure of the grating sensors FBG1, FBG2 on the beam elastic body BE1 and the symmetrical fixing structure of the grating sensors FBG3, FBG4 on the beam elastic body BE2 not only can double the load sensitivity, but also can offset the measurement error caused by the temperature influence on the fiber grating FBG1, FBG2, FBG3, FBG4.

[0065] Preferably, the first fiber grating assembly further comprises a first limiting block LB1, a second limiting block LB2 and a third limiting block LB3; the first limiting block LB1 is arranged on the side of the first beam elastic body BE1 away from the first force transmission assembly, and the first limiting block LB1 is used to limit the movement distance of the free end of the first beam elastic body VE1, thereby preventing the overpressure from causing the deformation of BE1 and BE2 to be too large and causing the fiber grating sensors FBG1, FBG2 to be overloaded, and facilitating the normal work of the fiber grating liquid pressure transmitting device. The fourth limiting block LB4 in the second fiber grating assembly is the same.

[0066] The second limiting block LB2 and the third limiting block LB3 are arranged in the liquid containing cavity, the second limiting block LB2 and the third limiting block LB3 are located on the same plane, and the plane where the second limiting block LB2 and the third limiting block LB3 are located is parallel to the end surface of the first isolation component; the second limiting block LB2 and the third limiting block LB3 are used to limit the movement of the first isolation component to the liquid containing cavity, specifically to limit the movement of the micro piston MP1 to the liquid containing cavity VCl. The fifth limiting block LB5 and the sixth limiting block LB6 in the second fiber grating assembly are the same.

[0067] The first fiber grating assembly further comprises a first sealing end cover EC1; the first sealing end cover EC1 is arranged on the side of the first Bernoulli elastic body BE1 away from the first force transmission assembly. Specifically, it is located on the side of the first fiber grating assembly away from the first Bernoulli elastic body, so as to isolate the fiber grating sensors FBG1 and FBG2 from the external environment, prevent dust, and protect the fiber grating FBG1 and FBG2. The second sealing end cover EC2 in the second fiber grating assembly is the same.

[0068] In summary, in the present application, the liquid containing cavity contains the liquid to be measured, under the pressure of the liquid to be measured, the first isolation component drives the first force transmission assembly to move in the direction of the first Bernoulli elastic body, at the same time, the second isolation component drives the second force transmission assembly to move in the direction of the second Bernoulli elastic body; the first force transmission assembly applies force to the first Bernoulli elastic body, so that the first Bernoulli elastic body deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; the second force transmission assembly applies force to the second Bernoulli elastic body, so that the second Bernoulli elastic body deforms and drives the third fiber grating sensor and the fourth fiber grating sensor to deform. The fiber grating liquid pressure measuring device of the present application realizes a wide pressure measurement range and high pressure measurement precision, and at the same time, the pressure transmitting device has the characteristics of high anti-electromagnetic interference, and has important application value and practicability in the liquid pipe network pressure monitoring system. Through the structural design of the limiting block, the fiber grating sensor can be guaranteed to work within the rated pressure range, and the Bernoulli elastic body and the fiber grating sensor are prevented from being damaged.

[0069] As shown in Figure 2 The present application embodiment further provides a fiber grating liquid pressure measurement method, which is applied to the above-mentioned fiber grating liquid pressure measurement device, and the method comprises the following steps:

[0070] In step 100, the force load sensitivity on the first Bernoulli elastic body and the cross-sectional area of the first isolation assembly are obtained.

[0071] Step 200, after the liquid cavity contains the liquid to be measured, the total wavelength shift of the first fiber grating sensor, the total wavelength shift of the second fiber grating sensor, the total wavelength shift of the third fiber grating sensor and the total wavelength shift of the fourth fiber grating sensor are obtained.

[0072] Step 300, according to the total wavelength shift of the first fiber grating sensor, the total wavelength shift of the second fiber grating sensor, the total wavelength shift of the third fiber grating sensor, the total wavelength shift of the fourth fiber grating sensor and the force load sensitivity on the first beam elastic body, the first action force is calculated; the first action force is the action force on the first beam elastic body under the pressure of the liquid to be measured in the liquid cavity.

[0073] Step 400, according to the first action force and the cross-sectional area of the first isolation component, the liquid pressure value is calculated; the liquid pressure value is the pressure value of the liquid to be measured in the liquid cavity.

[0074] Wherein, the calculation formula of the first action force is:

[0075] Δλ FBG2 -Δλ FBG1 +Δλ FBG3 -Δλ FBG4 =4k F21 F 21 ;

[0076] Wherein, Δλ FBG1 represents the total wavelength shift of the first fiber grating sensor, that is, the total wavelength shift caused by deformation and temperature change of the fiber grating sensor FBG1, Δλ FBG2 represents the total wavelength shift of the second fiber grating sensor, that is, the total wavelength shift caused by deformation and temperature change of the fiber grating sensor FBG2, Δλ FBG3 represents the total wavelength shift of the third fiber grating sensor, that is, the total wavelength shift caused by deformation and temperature change of the fiber grating sensor FBG3, Δλ FBG4 represents the total wavelength shift of the fourth fiber grating sensor, that is, the total wavelength shift caused by deformation and temperature change of the fiber grating sensor FBG4, k F21 represents the force load sensitivity on the first beam elastic body, F 21 represents the first action force.

[0077] The calculation formula of the liquid pressure value is:

[0078] P2=F 21 ×S MP1 ;

[0079] Wherein, F 21P1 represents the first force, P2 represents the liquid pressure value, S MP1 represents the cross-sectional area of the first isolation component, i.e. the cross-sectional area of the micro piston MP1.

[0080] The various embodiments are described in a progressive manner in the specification, each of which focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be understood by referring to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be understood by referring to the method part.

[0081] The principles and implementation manners of the present application are described by applying specific examples in this paper, and the above embodiment description is only used to help understand the method of the present application and its core idea; at the same time, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manner and application range will be changed. In view of the above, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A fiber optic Bragg grating liquid pressure measurement device, characterized by, The device comprises a shell, a first fiber grating assembly and a second fiber grating assembly; the first fiber grating assembly and the second fiber grating assembly are arranged in the shell; The first fiber grating assembly comprises a first isolation component, a first force transmission assembly, a first beam elastic body, a first fiber grating sensor and a second fiber grating sensor; the second fiber grating assembly comprises a second isolation component, a second force transmission assembly, a second beam elastic body, a third fiber grating sensor and a fourth fiber grating sensor; The first isolation component and the second isolation component form a liquid containing cavity; the first force transmission assembly is arranged on the end face of the first isolation component away from the liquid containing cavity; the end face of the first force transmission assembly away from the first isolation component is adjacent to the end face of the first beam elastic body; the first fiber grating sensor and the second fiber grating sensor are symmetrically arranged on the two end faces of the first beam elastic body, and the second fiber grating sensor and the first force transmission assembly are located on the same side of the first beam elastic body; The second fiber grating assembly has the same structure as the first fiber grating assembly; In operation, the liquid containing cavity contains a liquid to be measured; under the pressure of the liquid to be measured, the first isolation component drives the first force transmission assembly to move towards the first beam elastic body, while the second isolation component drives the second force transmission assembly to move towards the second beam elastic body; the first force transmission assembly applies force to the first beam elastic body, so that the first beam elastic body deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; the second force transmission assembly applies force to the second beam elastic body, so that the second beam elastic body deforms and drives the third fiber grating sensor and the fourth fiber grating sensor to deform.

2. The fiber optic Bragg grating liquid pressure measurement device of claim 1, wherein, The first force transmission assembly comprises a first wedge-shaped body and a first hemispherical body; The first wedge-shaped body is arranged on the end face of the first isolation component away from the liquid containing cavity; the first hemispherical body is arranged on the end face of the first wedge-shaped body away from the first isolation component, and the arc surface of the first hemispherical body is adjacent to the end face of the first beam elastic body.

3. The fiber optic Bragg grating liquid pressure measurement device of claim 2, wherein, The first beam elastic body comprises a fixed end and a free end; The fixed end is fixedly arranged on the shell, and the free end is adjacent to the arc surface of the first hemispherical body; When not subjected to the force applied by the first hemispherical body, the plane in which the fixed end and the free end are located is perpendicular to the surface of the shell; when subjected to the force applied by the first hemispherical body, the free end moves.

4. The fiber optic Bragg grating liquid pressure measurement device of claim 3, wherein, The first fiber grating assembly further comprises a first limiting block, a second limiting block and a third limiting block; The first limiting block is arranged on the side of the first beam elastic body away from the first force transmission assembly, and the first limiting block is used to limit the movement distance of the free end of the first beam elastic body; The second limiting block and the third limiting block are arranged in the liquid containing cavity, the second limiting block and the third limiting block are located on the same plane, and the plane where the second limiting block and the third limiting block are located is parallel to the end surface of the first isolation component; the second limiting block and the third limiting block are used to limit the movement of the first isolation component to the liquid containing cavity.

5. The fiber-optic Bragg grating liquid pressure measurement device of claim 1, wherein, The threaded damping hole is arranged on the shell, and is used to inject the to-be-tested liquid into the liquid containing cavity.

6. The fiber-optic Bragg grating liquid pressure measurement device of claim 1, wherein, The first fiber grating assembly further comprises a first sealing end cover; The first sealing end cover is arranged on the side of the first Leibniz elastic body away from the first force transmission assembly.

7. A method of fiber grating liquid pressure measurement, applied to the fiber grating liquid pressure measurement device of any one of claims 1-6, characterized in that the method Comprise: Obtaining the force load sensitivity on the first Leibniz elastic body and the cross-sectional area of the first isolation assembly; After the to-be-tested liquid is contained in the liquid containing cavity, the total wavelength drift of the first fiber grating sensor, the total wavelength drift of the second fiber grating sensor, the total wavelength drift of the third fiber grating sensor and the total wavelength drift of the fourth fiber grating sensor are obtained; According to the total wavelength drift of the first fiber grating sensor, the total wavelength drift of the second fiber grating sensor, the total wavelength drift of the third fiber grating sensor, the total wavelength drift of the fourth fiber grating sensor and the force load sensitivity on the first Leibniz elastic body, the first acting force is calculated. The first acting force is the acting force on the first Leibniz elastic body under the pressure of the to-be-tested liquid in the liquid containing cavity; According to the first acting force and the cross-sectional area of the first isolation assembly, the liquid pressure value is calculated; the liquid pressure value is the pressure value of the to-be-tested liquid in the liquid containing cavity.

8. The fiber-optic Bragg grating liquid pressure measurement method of claim 7, wherein, The calculation formula of the first acting force is: Δλ FBG2 -Δλ FBG1 +Δλ FBG3 -Δλ FBG4 = 4k F21 F 21 ; where Δλ FBG1 represents the total wavelength drift of the first fiber grating sensor, Δλ FBG2 represents the total wavelength drift of the second fiber grating sensor, Δλ FBG3 represents the total wavelength drift of the third fiber grating sensor, Δλ FBG4 represents the total wavelength drift of the fourth fiber grating sensor, k F21 represents the force load sensitivity on the first beam-like elastic body, F 21 represents the first force.

9. The fiber-optic Bragg grating liquid pressure measurement method of claim 7, wherein, The calculation formula of the liquid pressure value is: P2 = F 21 x S MP1 ; wherein F 21 represents the first force, P2represents the liquid pressure value, S MP1 represents the cross-sectional area of the first isolation assembly.

Images