CN204831682U - Measure cantilever beam type optic fibre bragg grating sensor of defeated oil pipe oil pressure - Google Patents

Abstract

The utility model relates to a measure cantilever beam type optic fibre bragg grating sensor of defeated oil pipe oil pressure belongs to photoelectronic measuring element technical field. The utility model discloses utilize the oil pressure in the defeated oil pipe to change drive piston motion, the removal of piston makes the cantilever beam warp, paste the deformation that differential type optic fibre bragg grating detected the cantilever beam on the cantilever beam, and then the accurate measurement goes out oil transportation pressure. The utility model discloses there is following benefit: the utility model discloses can be as required, through the measuring sensitivity who changes guide arm and the contact position adjustment sensor of cantilever beam, the utility model discloses any signal of telecommunication is not taken to sensor itself, and the especially adapted liquid that is arranged in high -risk environment such as inflammable and explosive detects, adoption optic fibre bragg grating makes the sensor have stronger anti -electromagnetic interference ability and corrosion -resistant ability as the measurement element of sensor, the utility model discloses simple structure, the installation of being convenient for.

Description

A Cantilever Beam Optical Fiber Bragg Grating Sensor for Measuring Oil Pressure in Oil Pipeline

technical field

The utility model relates to the technical field of optoelectronic measuring devices, in particular to a cantilever beam type optical fiber Bragg grating sensor for measuring the oil pressure of an oil pipeline.

Background technique

The oil pipeline is an important equipment for transporting oil, and the accurate measurement of the oil pressure in the oil pipeline has a great influence on the transportation capacity and safety of the oil pipeline. However, many domestic oil pressure sensors for measuring oil pipelines use resistive sensors, which can easily lead to static electricity in the measurement system, and even ionization in some cases, causing discharge and sparks, and are susceptible to environmental noise and noise during the signal amplification process. Because of the influence of electromagnetic interference and other factors, it is not conducive to be extended to the detection of oil pressure in oil pipelines.

The utility model uses the oil pressure in the oil delivery pipe to drive the piston to move, and the movement of the piston drives the deformation of the cantilever beam. A differential optical fiber Bragg grating is pasted on the cantilever beam to detect the deformation of the cantilever beam, and then accurately measure the oil delivery pressure. Resistive sensors are prone to static electricity, and the signal amplification process is easily affected by factors such as environmental noise and electromagnetic interference.

Contents of the invention

The technical problem to be solved by the utility model is to provide an anti-electromagnetic interference, intrinsically safe sensor for the problems that the existing resistive sensor for measuring the oil pressure of the oil pipeline is easy to generate static electricity, and is easily affected by factors such as environmental noise and electromagnetic interference during the signal amplification process. , wide dynamic range, high sensitivity, easy to network, and can realize distributed measurement of the cantilever beam fiber Bragg grating sensor for measuring the oil pressure of the oil pipeline.

The utility model cantilever beam type optical fiber Bragg grating sensor for measuring the oil pressure of the oil pipeline is completed through the following technical scheme: the sensor is composed of a cantilever beam (1), an optical fiber lead-out hole (2), a lead-out optical fiber (3), and an optical fiber Bragg grating (4 ), a pressure-bearing piston (5), an iron casing (9), a guide rod (10), and a strong glue (11), wherein the pressure-bearing piston (5) matches the piston cylinder formed by the iron casing (9) , one end of the guide rod (10) is fixed together with the pressure-bearing piston (5), the other end of the guide rod (10) is fixed together with one end of the cantilever beam (1) by strong glue (11), and the cantilever beam (1 ) is fixed on the iron shell (9); two fiber Bragg gratings (4) are pasted on the upper and lower walls of the cantilever beam (1) respectively, and one end of the exported fiber (3) is connected to the fiber Bragg grating (4) connected, the leading optical fiber (3) is connected with the external optical cable through the fiber leading hole (2).

One end of the guide rod (10) is fixed with one end of the cantilever beam (1) by strong glue (11), and the guide rod (10) and the cantilever beam (1) are vertical in the same plane; the cantilever beam (1) ) is fixed on the iron casing (9), the cantilever beam (1) is perpendicular to the special casing (9); the guide rod (10) is perpendicular to the top surface of the piston (5).

The two fiber Bragg gratings (4) are respectively pasted on the upper and lower walls of the cantilever beam (1). The two fiber Bragg gratings are made of the same type of photosensitive optical fiber. The grating (4) constitutes a differential fiber Bragg grating, which can eliminate the influence of temperature on the wavelength of the fiber Bragg grating.

The lead-out optical fiber (3) is led out from the fiber lead-out hole (2), the fiber lead-out hole (2) is sealed with epoxy resin, and the inner cavity of the iron shell (9) forms a closed space.

The working principle of the cantilever beam type fiber optic Bragg grating sensor is: the pressure-bearing piston (5) transmits the oil pressure in the oil delivery pipe to the cantilever beam (1) through the guide rod (10), and the force on the left end of the cantilever beam (1) will be Bending upwards drives the fiber Bragg grating (4) on the upper wall of the cantilever beam (1) to compress and the fiber Bragg grating (4) on the wall of the cantilever beam (1) to stretch, converting the detection of the measured object into a fiber Bragg grating The modulation of the wavelength of the grating (4), the differential bonding of the fiber Bragg grating (4) helps to offset the influence of the ambient temperature, and the output fiber (3) of the fiber Bragg grating (4) is drawn out through the fiber output hole (2) and connected to the The external optical cables are connected to form a cantilever beam type optical fiber Bragg grating sensor for measuring the oil pressure in the oil pipeline.

The mathematical model of described cantilever beam type fiber Bragg grating sensor is:

The equation of F suffered by the pressure-bearing piston (5) is:

(a)

In the formula, P is the oil pressure in the oil delivery pipe, and S is the cross-sectional area of the pressure-bearing piston.

The guide rod 10 transmits the force received by the pressure-bearing piston (5) to the cantilever beam (1), and the force received by the left end of the cantilever beam is F.

The strain on each point of the cantilever beam (1) is:

(b)

In the formula, l is the working length of the constant strength cantilever beam (1), h is the thickness of the constant strength cantilever beam (1), B is the width of the fixed end of the constant strength cantilever beam (1), E is the constant strength cantilever beam (1) modulus of elasticity.

Put (a) into (b) to get:

(c)

When the equal-strength cantilever beam (1) is bent by F, the upper surface is subjected to tensile strain , while the lower surface is subjected to compressive strain , if the two gratings are in the same temperature field, the strain signal Expressed as:

(d)

In the formula, is the reflection wavelength of the fiber Bragg grating (4) after the lower surface is subjected to tensile strain, is the reflected wavelength of the fiber Bragg grating (4) after the upper surface is subjected to compressive strain, is the strain sensitivity coefficient of the fiber Bragg grating (4), is the initial central wavelength of the fiber Bragg grating (4).

The center wavelength difference of the fiber Bragg grating (4) pasted on the upper and lower walls of the cantilever beam (1) for:

(e)

Substituting (d) and (e) into (c) gives:

(f)

Equation (f) shows that the oil pressure P in the pipeline under test and the wavelength shift of the fiber Bragg grating (4) Based on the mathematical model, the oil pressure in the measured oil pipeline can be calculated by measuring the wavelength shift of the fiber Bragg grating (4).

Compared with the prior art, a cantilever beam type optical fiber Bragg grating sensor for measuring the oil pressure of the oil pipeline of the utility model has the following beneficial effects:

1. According to the needs, the measurement sensitivity of the sensor can be adjusted by changing the contact position between the guide rod and the cantilever beam.

2. The sensor of the utility model does not carry any electrical signal itself, and is very suitable for liquid detection in high-risk environments such as flammable and explosive.

3. The optical fiber Bragg grating is used as the measuring element of the sensor, so that the sensor has strong anti-electromagnetic interference ability and corrosion resistance.

4. The utility model has a simple structure and is easy to install.

Description of drawings

Fig. 1 is a structural schematic diagram of a cantilever beam type optical fiber Bragg grating sensor for measuring the oil pressure of the oil pipeline of the present invention.

Fig. 2 is a partial plan view schematic diagram of a cantilever beam type optical fiber Bragg grating sensor cantilever of the utility model for measuring the oil pressure of the oil pipeline.

In the figure, 1-cantilever beam, 2-fiber export hole, 3-leading fiber, 4-fiber Bragg grating, 5-pressure piston, 6-oil, 7-oil pipe wall, 8-oil pipe interface, 9-iron shell , 10-guide rod, 11-strong glue; B-cantilever beam fixed point width, - Cantilever beam working length.

Detailed ways

The technical scheme of a cantilever beam type optical fiber Bragg grating sensor for measuring the oil pressure of the oil pipeline of the present invention will be further described below in conjunction with the accompanying drawings and the working process.

Embodiment: as shown in Fig. 1 and Fig. 2, the cantilever beam type optical fiber Bragg grating sensor of the utility model for measuring the oil pressure of the oil pipeline is composed of a cantilever beam 1, an optical fiber lead-out hole 2, a lead-out optical fiber 3, an optical fiber Bragg grating 4, and a pressure-bearing piston 5 , iron shell 9, guide rod 10, and strong glue 11, wherein the pressure-bearing piston 5 matches the piston cylinder formed by the iron shell 9, and one end of the guide rod 10 is fixed with the pressure-bearing piston 5, and the guide rod 10 The other end of the cantilever beam 1 is fixed together with one end of the cantilever beam 1 by strong glue 11, and the other end of the cantilever beam 1 is fixed on the iron shell 9; two optical fiber Bragg gratings 4 are respectively pasted on the upper and lower walls of the cantilever beam 1, One end of the lead-out optical fiber 3 is connected with the fiber Bragg grating 4 , and the lead-out fiber 3 is connected with an external optical cable through the fiber lead-out hole 2 .

One end of the guide rod 10 is fixed together with one end of the cantilever beam 1 by strong glue 11, the guide rod 10 and the cantilever beam 1 are vertical in the same plane; the other end of the cantilever beam 1 is fixed on the iron shell 9, The cantilever beam 1 is perpendicular to the characteristic shell 9; the guide rod 10 is perpendicular to the top surface of the piston 5.

The two fiber Bragg gratings 4 are respectively pasted on the upper and lower walls of the cantilever beam 1. The two fiber Bragg gratings are made of the same type of photosensitive optical fiber. The upper and lower two fiber Bragg gratings 4 on the wall of the cantilever beam 1 form a differential type Fiber Bragg grating and differential fiber Bragg grating can eliminate the influence of temperature on the wavelength of fiber Bragg grating.

The lead-out optical fiber 3 is led out from the fiber lead-out hole 2, and the fiber lead-out hole 2 is sealed with epoxy resin, and the inner cavity of the iron shell 9 forms a closed space.

The working process of the utility model is as follows: when using the utility model, the iron shell 9 of the sensor is sealed and welded on the oil delivery pipe wall 7, so that the oil 6 is in contact with the pressure-bearing piston 5 through the oil delivery pipeline interface 8; The oil pressure in the oil pipeline is transmitted to the cantilever beam 1 through the guide rod 10, and the left end of the cantilever beam 1 is forced to bend upward, driving the fiber Bragg grating 4 on the upper wall of the cantilever beam 1 to compress and the fiber Bragg grating 4 on the wall of the cantilever beam 1 to pull The detection of the measured object is transformed into the modulation of the wavelength of the fiber Bragg grating 4, the differential bonding of the fiber Bragg grating 4 helps to offset the influence of the ambient temperature, and the export fiber 3 of the fiber Bragg grating 4 passes through the fiber export hole 2 lead out and connect with the external optical cable, and transmit the signal to the external data acquisition machine. Among them, the specific parameters of the sensor are:

1. The size parameters of the cantilever beam 1 are: the working length l is 40mm, the fixed point width B is 20mm, the Young’s modulus of No. 45 steel is E = 200GPa, and the cantilever beam thickness h is 5mm;

2. The technical parameters of fiber Bragg grating 4 are: central wavelength = 1550.000nm, ;

3. The size parameters of the pressure-bearing piston 5 are: the length is 5mm, the width is 5mm, and the area S is 5×5mm ² ;

4. Configure and install the sensor according to Figure 1;

5. Obtain the Bragg wavelength of the fiber Bragg grating 4 with a fiber grating demodulator;

6. According to the formula (f), the oil pressure of the sensor to be measured can be calculated by the center wavelength difference △λ _B of the fiber Bragg grating 4 pasted on the upper and lower walls of the cantilever beam;

Substituting each known quantity into the above formula, the theoretical calculation shows that when the oil pressure is 5×10 ⁶ Pa, the wavelength change is 725.401pm.

The specific implementation of the utility model has been described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned implementation. Various changes are made.

Claims (4)

1. measure the beam type optical fiber Bragg grating sensor of petroleum pipeline oil pressure for one kind, it is characterized in that this sensor is by semi-girder (1), optical fiber leadout hole (2), derive optical fiber (3), optical fiber Bragg raster (4), pressure-bearing piston (5), iron shell (9), guide rod (10), epistasis glue (11) forms, the piston cylinder that wherein pressure-bearing piston (5) and iron shell (9) are formed matches, one end and the pressure-bearing piston (5) of guide rod (10) are fixed together, the other end of guide rod (10) is fixed together by epistasis glue (11) one end with semi-girder (1), the other end of semi-girder (1) is fixed on iron shell (9), two optical fiber Bragg rasters (4) are pasted onto on upper and lower two walls of semi-girder (1) respectively, and the one end of deriving optical fiber (3) is connected with optical fiber Bragg raster (4), derive optical fiber (3) and are connected with external optical cable by optical fiber leadout hole (2).

2. the beam type optical fiber Bragg grating sensor of the measurement petroleum pipeline oil pressure according to claims 1, it is characterized in that one end of guide rod (10) is fixed together by epistasis glue (11) one end with semi-girder (1), guide rod (10) is vertical in same plane with semi-girder (1); The other end of semi-girder (1) is fixed in iron shell (9), and semi-girder (1) is vertical with speciality shell (9); Guide rod (10) is perpendicular to the end face of piston (5).

3. the beam type optical fiber Bragg grating sensor of the measurement petroleum pipeline oil pressure according to claims 1, it is characterized in that two optical fiber Bragg rasters (4) are pasted onto on upper and lower two walls of semi-girder (1) respectively, two optical fiber Bragg rasters adopt the light-sensitive optical fibre of same model to make, and two optical fiber Bragg rasters (4) up and down of semi-girder (1) wall form differential optical fiber Bragg grating.

4. the beam type optical fiber Bragg grating sensor of the measurement petroleum pipeline oil pressure according to claims 1, it is characterized in that deriving optical fiber (3) derives from optical fiber leadout hole (2), optical fiber leadout hole (2) adopts epoxy resin to seal.