CN100523754C - Optical fibre pressure intensity sensor based on beam of constant strength - Google Patents

Abstract

An optical fiber pressure sensor based on an equal-intensity beam, comprising: a support cylinder, which is a cylinder body, which is the main body of the optical fiber pressure sensor, and two circular holes are opened at opposite positions on the lower wall surface; a diaphragm is fixed on the lower end of the support cylinder ; One end cover is installed on the upper end of the support tube to seal the support tube; the first-class strength beam is L-shaped, one side of the equal-strength beam is fixed on the side wall inside the support tube, and there is a gap between the other side and the diaphragm , there is a boss between the equal-intensity beam and the center of the diaphragm, which is used to transmit the deformation of the diaphragm; a fiber grating is fixed on the bottom surface between the equal-intensity beam and the diaphragm, and the tails at both ends of the fiber grating The fibers are respectively led out from two round holes on the support tube; a temperature compensation fiber grating is fixed on the inner surface of the end cover, and the pigtail at one end of the temperature compensation fiber grating is led out from a round hole on the support tube.

Description

Optical Fiber Pressure Sensor Based on Equal Intensity Beam

technical field

The invention relates to the technical field of optical fiber sensors, in particular to an optical fiber pressure sensor based on equal-intensity beams.

Background technique

Compared with the corresponding conventional sensors, optical fiber sensors have obvious advantages in terms of sensitivity, dynamic range, reliability, etc., especially in the fields of construction, petroleum, and military applications.

The optical fiber pressure sensor is an instrument that detects the pressure of the surrounding environment by using the light transmission characteristics of the optical fiber and various modulation effects generated by its interaction with the surrounding environment. Compared with traditional pressure sensors, it has the following main advantages: high pressure sensitivity, no electromagnetic interference, light weight, high temperature resistance, compact structure, high reliability, and the advantages of both information sensing and optical information transmission. .

In view of the above technical advantages of optical fiber pressure sensors, they can meet the requirements of various developed countries in the fields of petroleum and military affairs, and research has been actively carried out in this area.

Among the common intensity-modulated, digital, and fiber-optic grating-type fiber-optic pressure sensors, the fiber-optic grating-type fiber-optic pressure sensor is the main research direction at present.

Fu Haiwei and Fu Junmei et al. reported a fiber grating pressure sensor, which uses the method of bonding one end of the fiber grating to the linear diaphragm for sensitization, and drives the fiber grating to generate pressure through the displacement of the circular diaphragm in the normal direction. strain to detect pressure. The optical fiber pressure sensor produced in this way requires prestressed bonding of optical fibers, and adopts point bonding, the process is complicated, the linear diaphragm is thin, it is difficult to measure high pressure, and it is sensitive to temperature changes.

Therefore, how to simplify the process, increase the pressure measurement range of the sensor, and eliminate temperature sensitivity is one of the important technologies that must be solved for the practical application of optical fiber pressure sensors.

Contents of the invention

technical problem to be solved

In view of this, the main purpose of the present invention is to provide an optical fiber pressure sensor to reduce the difficulty of the packaging process of the optical fiber pressure sensor, increase the pressure measurement range of the sensor, and perform temperature compensation.

Technical scheme of the present invention

In order to achieve the above object, technical solution of the present invention is achieved in that way:

An optical fiber pressure sensor based on an equal-intensity beam of the present invention is characterized in that it comprises:

A support cylinder, which is a cylinder, the support cylinder is the main body of the optical fiber pressure sensor, and the lower wall of the support cylinder is opposite to each other with two round holes;

A diaphragm, the diaphragm is fixed on the lower end of the support cylinder;

an end cover, which is installed on the upper end of the support tube and used to seal the support tube;

First-class strength beams, these strength beams are L-shaped, one side of these strength beams is fixed on the side wall inside the support tube, there is a gap between the other side of these strength beams and the diaphragm, and these strength beams and There is a boss between the center of the diaphragm, which is used to transmit the deformation of the diaphragm;

A fiber grating, the fiber grating is fixed on the bottom surface between the equal-intensity beam and the diaphragm, and the pigtails at both ends of the fiber grating are led out from two circular holes on the support cylinder;

A temperature compensation fiber grating, the temperature compensation fiber grating is fixed on the inner surface of the end cover, and the tail fiber at one end of the temperature compensation fiber grating is led out from a circular hole on the support cylinder.

Wherein the diaphragm and the supporting cylinder are of a separate structure or an integrated structure.

The diaphragm described herein is thick in the center and gradually thinner at the edges.

The constant-strength beams are fixed on the inner wall of the support cylinder by means of bolts or bonding.

The fiber grating and temperature compensation fiber grating are fixed by bonding.

The end of the boss in contact with the equal-intensity beam has a groove for passing through the pigtail of the fiber grating.

The circular hole on the side wall of the support cylinder is further equipped with a cylindrical connector for fixing the fiber grating and the tail fiber of the temperature compensation fiber grating.

Wherein the connection between the support cylinder and the end cover and the inside of the cylindrical joint are coated with high-strength sealant, so that the inside of the support cylinder forms a closed air cavity.

The thermal expansion coefficient of the material of the end cap and the support cylinder is the same.

Beneficial effect

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. The process is simple. By bonding the fiber grating to the metal surface for pressure detection and temperature compensation, the difficulty of the process is reduced, and the consistency of the process is easy to ensure.

2. The sound pressure sensitivity is easy to control. The sensitivity of the optical fiber pressure sensor can be adjusted by adjusting the thickness of the equal-intensity beam 40 , the thickness of the diaphragm 20 , geometric parameters such as radius, or material parameters such as elastic modulus.

3. Eliminate the influence of external temperature changes. The temperature compensation is performed by the temperature compensation fiber grating 60, so that the deviation of the sensor caused by the change of the external temperature is eliminated.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings, wherein:

Fig. 1 is a schematic cross-sectional view of the structure of the optical fiber pressure sensor provided by the present invention.

FIG. 2 is a schematic diagram of the boss 41 in FIG. 1 .

Detailed ways

As shown in FIG. 1 , FIG. 1 is a schematic structural cross-sectional view of an optical fiber pressure sensor based on an equal-intensity beam provided by the present invention. The optical fiber pressure sensor includes: a support cylinder 10, which is a cylindrical body, the support cylinder 10 is the main body of the optical fiber pressure sensor, and two circular holes 11, 12 are opened on the opposite position of the lower wall of the support cylinder 10; a diaphragm 20 , the diaphragm 20 is fixed on the lower end of the support tube 10 for sensing external pressure; an end cover 30 is installed on the upper end of the support tube 10 for sealing the support tube 10; a first-class strength beam 40, the The strength beams 40 are L-shaped. One side of the strength beams 40 is fixed on the side wall of the support tube 10. There is a gap between the other side of the strength beams 40 and the membrane 20. The strength beams 40 and the membrane There is a boss 41 between the center of the sheet 20, the boss 41 is used to transmit the deformation of the diaphragm 20 to the end of the equal strength beam; a fiber grating 50, the fiber grating 50 is fixed on the equal strength beam 40 and the diaphragm The bottom surface between 20 is used to feel the strain on the equal-intensity beam. The pigtails at both ends of the fiber grating 50 are respectively drawn from the two round holes 11 and 12 on the support cylinder 10; a temperature compensation fiber grating 60, the temperature compensation The fiber grating 60 is fixed on the inner surface of the end cap 30 for sensing temperature changes and performing temperature compensation. The pigtail at one end of the temperature compensating fiber grating 60 is led out from a circular hole 11 on the support cylinder 10 .

The diaphragm 20 and the support cylinder 10 can be made into a separate structure or an integral structure by adopting different processing methods. In addition, the diaphragm 20 has a thick center and gradually thinner edges, so that under the same pressure, greater deformation will occur.

The equal-strength beam 40 is fixed on the inner wall of the support cylinder 10 by means of bolts or bonding.

The fiber grating 50 and the temperature compensating fiber grating 60 are fixed by bonding.

A groove 42 (in FIG. 2 ) is opened at the end of the boss 41 in contact with the equal-strength beam 40 for passing the pigtail of the fiber grating 50 .

Cylindrical connectors 13 and 14 are further installed in the circular holes 11 and 12 on the side wall of the support cylinder 10 for fixing the pigtails of the fiber Bragg grating 50 and temperature compensation fiber grating 60 drawn out.

The connection between the support cylinder 10 and the end cap 30 and the inside of the cylindrical joints 13 and 14 are coated with high-strength sealant, so that the inside of the support cylinder 10 forms a closed air cavity. The end cap 30 and the side wall of the support cylinder 10 have sufficient rigidity to resist external pressure, and the thickness of the diaphragm 20 is generally much smaller than the thickness of the side wall of the support cylinder 10, so it is sensitive to external pressure and serves as a sensing element.

When external pressure acts on the sensor, the diaphragm 20 deforms and bends inward, and the deflection at its center is transmitted to the end of the equal-strength beam 40 through the boss 41, causing the equal-strength beam to bend. For constant strength beams, the strain on the surface is uniform, which drives the fiber grating 50 bonded on the constant strength beam 40 to generate uniform tensile strain, thereby causing changes in the reflection wavelength of the fiber grating. For fiber gratings, the variation of the reflected wavelength is proportional to the applied strain, so the external pressure can be obtained by detecting the variation of the wavelength.

The end cover 30 and the support cylinder 10 are made of materials with the same thermal expansion coefficient. When the external temperature changes, the change of the reflection wavelength of the fiber grating caused by the temperature change is the same for the sensor grating 50 and the temperature compensation fiber grating 60, so The influence of temperature change can be eliminated by subtracting the drift of its wavelength.

At the same time, the sensitivity of the optical fiber pressure sensor is related to multiple structure and material parameters. For example, the sensitivity of the optical fiber pressure sensor can be changed by adjusting the thickness of the constant intensity beam 40 and the elastic modulus of the material used. For another example, the sensitivity of the optical fiber pressure sensor can be adjusted by changing geometric parameters such as the thickness and radius of the diaphragm 20 or material parameters such as the elastic modulus of the material used for the diaphragm 20 .

In addition, the optical fiber grating 50 of the optical fiber pressure sensor and the pigtail fiber of the temperature compensation optical fiber grating 60 can be respectively connected in series with the sensing optical fiber and temperature compensation optical fiber of another optical fiber pressure sensor to perform multi-point measurement.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1, a kind of optical fiber pressure sensor based on the beam of uniform strength is characterized in that, comprising:

One support tube is a cylindrical shell, and this support tube is the main body of optical fiber pressure sensor, and the position that the lower wall surface of this support tube is relative has two circular holes;

One diaphragm, this diaphragm is fixed on the lower end of support tube;

One end cap, this end cap is installed in the upper end of support tube, is used to seal support tube;

One equal strength beam, this equal strength beam is one L shaped, and the one side of this equal strength beam is fixed on the sidewall in the support tube, and a gap is arranged between the another side of this equal strength beam and the diaphragm, between this equal strength beam and the diaphragm center boss is arranged, this boss is used to transmit the deformation of diaphragm;

One fiber grating, this fiber grating are fixed on the bottom surface between the beam of uniform strength and the diaphragm, and the tail optical fiber at these fiber grating two ends two circular holes from the support tube is respectively drawn;

One temperature compensation optical fiber grating, this temperature compensation optical fiber grating are fixed on the inner face of end cap, and the tail optical fiber of this temperature compensation optical fiber grating one end is drawn from the circular hole on the support tube.

2, optical fiber pressure sensor according to claim 1 is characterized in that, wherein said diaphragm and support tube are for dividing body structure or being structure as a whole.

3, optical fiber pressure sensor according to claim 1 and 2 is characterized in that, wherein said diaphragm is the structure that the center is thick, the edge is gradually thin.

4, optical fiber pressure sensor according to claim 1 is characterized in that, the wherein said beam of uniform strength is to be fixed on the inwall of support tube by bolt or bonding mode.

5, optical fiber pressure sensor according to claim 1 is characterized in that, the fixed form of wherein said fiber grating and temperature compensation optical fiber grating is to be adhesively fixed.

6, optical fiber pressure sensor according to claim 1 is characterized in that, the end that wherein said boss contacts with the beam of uniform strength has a groove, is used to pass the tail optical fiber of fiber grating.

7, optical fiber pressure sensor according to claim 3 is characterized in that, the column type joint further is installed in the circular hole of wherein said support tube sidewall, is used for fixing the fiber grating of drawing and the tail optical fiber of temperature compensation optical fiber grating.

8, according to claim 1 or 7 described optical fiber pressure sensors, it is characterized in that, scribble the high strength fluid sealant in wherein said support tube and end cap connection place and the column type joint, make the airtight air chamber of the inner formation of support tube.

9, optical fiber pressure sensor according to claim 1 is characterized in that, wherein said end cap is identical with support tube material coefficient of thermal expansion coefficient.

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