阅读说明：本技术 一种基于方形膜片的高灵敏度光纤光栅压力传感器 (High-sensitivity fiber grating pressure sensor based on square diaphragm ) 是由 贾振安 樊庆赓 冯德全 樊伟 赵显锋 杨凯庆 禹大宽 高宏 于 2019-10-18 设计创作，主要内容包括：一种基于方形膜片的高灵敏度光纤光栅压力传感器,包括：保护顶盖,其顶部中心处设置有光纤尾纤的引出孔,中间部件,其顶部表面有直接感受外界油气压力信号的方形承压膜片；安装于方形承压膜片中心的应力传递杆；安装于圆盘表面的两个垂直梁；安装于垂直梁自由端的横梁；安装于横梁上表面的测温光纤光栅；安装于应力传递杆和横梁之间的在封装时施加一定预应力的测压光纤光栅,压力端口,其内部中心处设置有压力传导通道；设置于压力端口底部的两个夹持凹槽。本发明具有灵敏度高,结构简单,尺寸小以及造价低廉等特点。(A high-sensitivity fiber grating pressure sensor based on a square diaphragm comprises: the top center of the protective top cover is provided with a leading-out hole of the optical fiber pigtail, the top surface of the middle part is provided with a square pressure-bearing diaphragm which can directly sense the external oil gas pressure signal; the stress transfer rod is arranged at the center of the square pressure-bearing membrane; two vertical beams mounted on the surface of the disc; a cross beam mounted at the free end of the vertical beam; the temperature measurement fiber bragg grating is arranged on the upper surface of the beam; the pressure measuring fiber grating is arranged between the stress transfer rod and the cross beam and applies certain prestress during packaging, and a pressure conduction channel is arranged at the center of the pressure port; two clamping grooves are arranged at the bottom of the pressure port. The invention has the characteristics of high sensitivity, simple structure, small size, low manufacturing cost and the like.)

1. A fiber bragg grating pressure sensor based on a square diaphragm is characterized by comprising a protective top cover (14), a middle part (12) and a pressure port (8) which are sequentially connected from top to bottom, wherein the top of the protective top cover (14) is provided with a fiber pigtail leading-out hole (1), the fiber pigtail leading-out hole (1) leads out a pressure-measuring fiber bragg grating (5) and a temperature-measuring fiber bragg grating (2) pigtail, the top surface of the middle part (12) is provided with a pressure-bearing diaphragm (6) used for sensing external oil gas pressure, the pressure-bearing diaphragm (6) is of a square structure, the center of the pressure-bearing diaphragm (6) is provided with a stress transmission rod (15), a disc (13) on the surface of the middle part (12) and the pressure-bearing diaphragm (6) are of an integrated structure, the surface of the disc (13) is provided with a vertical beam (4), the free end of the vertical beam (4) is provided with, a pressure measuring fiber grating (5) applying a certain prestress is arranged between the stress transfer rod (15) and the beam (3), and a pressure conduction channel (7) is arranged in the pressure port (8).

2. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the protective top cover (14) and the middle part (12) are both cylindrical structures, and the pressure port (8) is a 'T' -shaped structure.

3. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the pressure conduction channel (7) is arranged at the inner center of the pressure port (8), and two clamping grooves (9) are arranged on the pressure port (8).

4. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the cross section of the stress transmission rod (15) is a square structure.

5. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the vertical beam (4) and the cross beam (3) are both uniform-section beams and are of an integrated design.

6. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the pressure measuring fiber grating (5) and the temperature measuring fiber grating (2) are in the same temperature field.

7. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the protective cover (14) is connected with the middle part (12) through a thread (11).

8. The square diaphragm-based high-sensitivity fiber grating pressure sensor as claimed in claim 1, wherein the intermediate member (12) is connected with the pressure port (8) by welding (10).

Technical Field

The invention relates to the technical field of fiber grating sensing detection, in particular to a high-sensitivity fiber grating pressure sensor based on a square diaphragm.

Background

The traditional electronic pressure transmitter, such as a capacitance type, a piezoresistive type, an inductance type, a piezoelectric resonance pressure transmitter and the like, is a sensor mainly used for monitoring the pressure of most oil and gas pipelines at the present stage. The electronic pressure transmitter can convert the physical pressure parameters of the outside gas and liquid into standard electric signals. In the process of signal transmission, the electric signal is attenuated due to the impedance of the transmission line, and the transmitter is easily interfered in the environments of high temperature, high pressure, electromagnetic radiation and the like. The electronic pressure transmitter has high nonlinearity and hysteresis error, which can affect the measurement accuracy of the sensor, and can cause different damage when contacting with corrosive or overheated media, and also has the defects of complex production process, short service life, poor stability and the like.

At present, a pressure sensor for detecting strain by using a fiber bragg grating mostly uses a circular diaphragm as a pressure sensitive element. The pressure of the outside liquid and gas acts on the circular diaphragm, and the pressure difference between the two sides of the diaphragm causes the circular diaphragm to deform. Compared with a square diaphragm, under the same pressure load, the circular diaphragm has lower central deflection under the condition of the same size and processing material, namely the circular diaphragm has lower sensitivity to the change of the external loading pressure.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a square-diaphragm-based high-sensitivity fiber grating pressure sensor which has the characteristics of high sensitivity, simple structure and capability of realizing temperature self-compensation.

In order to achieve the purpose, the invention adopts the technical scheme that:

a high-sensitivity fiber grating pressure sensor based on a square diaphragm comprises a protection top cover 14, a middle part 12 and a pressure port 8 which are sequentially connected from top to bottom; the top of the protective top cover 14 is provided with an optical fiber pigtail leading-out hole 1, and a pressure measuring optical fiber grating 5 and a temperature measuring optical fiber grating 2 are led out of the optical fiber pigtail leading-out hole 1; the top surface of the middle part 12 is provided with a pressure-bearing diaphragm 6 for sensing the external oil-gas pressure, the pressure-bearing diaphragm 6 is of a square structure, and the center of the pressure-bearing diaphragm 6 is provided with a stress transfer rod 15; the disc 13 on the surface of the middle part 12 and the pressure-bearing diaphragm 6 are of an integrated structure, and two vertical beams 4 are arranged on the surface of the disc 13; the free end of the vertical beam 4 is provided with a cross beam 3, the upper surface of the cross beam 3 is provided with a temperature measurement fiber grating 2, a pressure measurement fiber grating 5 is arranged between the stress transfer rod 15 and the cross beam 3, and a pressure conduction channel 7 is arranged in the pressure port 8.

The protective top cover 14 and the middle part 12 are both cylindrical structures, and the pressure port 8 is of a T-shaped structure.

The pressure conduction channel 7 is arranged in the center of the inside of the pressure port 8, and two clamping grooves 9 are arranged on two sides of the pressure port 8.

The cross section of the stress transmission rod 15 is of a square structure.

The vertical beam 4 and the cross beam 3 are both beams with equal sections and are of an integrated structure.

The pressure measuring fiber grating 5 needs to be pre-stressed when being fixed.

The pressure measuring fiber grating 5 and the temperature measuring fiber grating 2 are in the same temperature field.

The protective cap 14 is connected to the intermediate part 12 by means of a thread 11.

The intermediate part 12 is connected to the pressure port 8 by a weld 10 to ensure tightness.

The invention has the beneficial effects that:

the high-sensitivity fiber bragg grating pressure sensor based on the square diaphragm provided by the invention has the advantage that under a certain pressure, the central deflection of the square diaphragm made of the same material and with the same size is higher than that of the circular diaphragm. The simulation shows that the fiber bragg grating pressure sensor using the square diaphragm as the pressure bearing element can improve the pressure sensitivity by thirty percent.

The high-sensitivity fiber grating pressure sensor based on the square diaphragm provided by the invention can adjust the sensitivity and the measuring range of the fiber grating pressure sensor by changing the length and the thickness of the pressure-bearing diaphragm so as to adapt to the monitoring requirements of different occasions.

The high-sensitivity fiber grating pressure sensor based on the square diaphragm provided by the invention adopts a double-grating design, and the two gratings are close to each other, so that the two gratings can be considered to be in the same temperature field, and the temperature self-compensation is realized.

Compared with a round diaphragm, the square-diaphragm-based high-sensitivity fiber bragg grating pressure sensor provided by the invention has the advantage that the actual processing is more convenient by adopting the square pressure-bearing diaphragm.

According to the high-sensitivity fiber grating pressure sensor based on the square diaphragm, the combination structure of the vertical beam and the cross beam is used, so that the shock resistance and the stability of the sensor are better.

Drawings

Fig. 1 is a cross-sectional view of a high-sensitivity fiber grating pressure sensor based on a square diaphragm provided by the invention along the center of a stress transmission rod.

FIG. 2 is a top view of the middle part of the square diaphragm-based high-sensitivity fiber grating pressure sensor provided by the invention.

FIG. 3 is a top view of a square diaphragm based fiber grating pressure sensor pressure port provided by the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1 and fig. 2, the high-sensitivity fiber grating pressure sensor based on a square diaphragm provided by the invention comprises: the protective cover 14 is a cylindrical structure, and the center of the top of the protective cover is provided with a leading-out hole 1 for leading out the tail fibers of the pressure measuring fiber bragg grating 5 and the temperature measuring fiber bragg grating 2. The middle part 12 is of a cylindrical structure, and the top surface of the middle part is provided with a square pressure-bearing diaphragm 6 for directly sensing the external oil gas pressure; a stress transfer rod 15 arranged at the center of the square pressure-bearing membrane 6; two vertical beams 4 mounted on the surface of the disc 13; the free end of the vertical beam 4 is provided with a cross beam 3; the temperature measurement fiber bragg grating 2 is arranged on the upper surface of the beam 3; the pressure measuring fiber grating 5 is arranged between the stress transmission rod 15 and the beam 3; the pressure port 8 is of a T-shaped structure, and a pressure conduction channel 7 (shown in FIG. 3) is arranged at the center of the pressure port; two clamping grooves 9 are provided at the bottom of the pressure port 8.

The pressure-bearing diaphragm 6 is of a square structure, and the responsiveness of external pressure and the central deflection of the pressure-bearing diaphragm caused by the external pressure is improved.

The cross section of the stress transmission rod 15 is of a square structure.

And a certain prestress is required to be applied to the pressure measuring fiber grating 5 during packaging.

The two vertical beams 4 and the cross beam 3 are both beams with equal sections and are designed integrally.

The pressure-bearing membrane 6 generates transverse displacement due to external pressure and is transmitted to the pressure-measuring fiber grating 5 by the stress transmission rod 5, so that the pressure-measuring fiber grating 5 in a pre-stretched state is contracted, and the central reflection wavelength is reduced.

The sensitivity and the measuring range of the fiber grating pressure sensor are adjusted by changing the length and the thickness of the pressure-bearing diaphragm 6.

The fiber grating pressure sensor adopts a double grating design, and can be identified as being in the same temperature field due to the fact that the pasting position is close, the influence of the external temperature can be eliminated, and temperature self-compensation is achieved.

The working principle of the invention is as follows:

the working principle of the high-sensitivity fiber grating pressure sensor based on the square diaphragm provided by the invention is that as a certain prestress is applied to the pressure measuring fiber grating 6 during packaging, when the external oil gas pressure acts on the square pressure-bearing diaphragm 6 through the pressure conduction channel 7, the generated transverse central displacement is transmitted to the pressure measuring fiber grating 6 through the stress transmission rod 5, so that the pressure measuring fiber grating 6 in a pre-stretching state is contracted, the output Bragg central reflection wavelength is changed, and the wavelength change is detected through the demodulation equipment, so that the external oil gas pressure signal is demodulated. The temperature measuring fiber grating 2 is in a free state and is only influenced by temperature, the pressure measuring fiber grating 5 and the temperature measuring fiber grating 2 are in the same temperature field, and the working temperature is the same, so that the temperature self-compensation of the sensor is realized.