High-reliability pressure-isolating and pressure-picking type optical fiber pressure sensor and measuring method

Abstract

The invention discloses a high-reliability pressure-isolating and pressure-picking type optical fiber pressure sensor and a measuring method.The high-reliability pressure-isolating and pressure-picking type optical fiber pressure sensor comprises a sensor component, a first optical fiber, a second optical fiber, a temperature compensation boss and a diaphragm, the first optical fiber, the second optical fiber, the temperature compensation boss and the diaphragm are located in the sensor component, and the sensor component comprises a cylinder, a fixing piece and a sealing component and forms a pressure-isolating cavity; the first optical fiber is arranged in a temperature compensation boss connected with the fixing piece, the second optical fiber is connected with the fixing piece, the second optical fiber and the cylinder body form a synchronous microcavity temperature compensation structure, the diaphragm is arranged in the cylinder body, the diaphragm and the first optical fiber form a Fabry-Perot cavity, and the sensor component and the temperature compensation boss form a temperature self-compensation structure; according to the sensor, single pressure sensing of the diaphragm is achieved through the design of the pressure isolation cavity, the influence of temperature on the cavity length is greatly reduced through the temperature self-compensation structure and the synchronous microcavity temperature compensation structure, different measurement ranges are met by reasonably designing size parameters of the diaphragm, the creep deformation problem of the diaphragm is restrained through the diaphragm with the homogenized stress, and the measurement accuracy is improved. And the reliability and the stability of the sensor are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and particularly to a highly reliable pressure-isolated and pressure-pickup fiber optic pressure sensor and a measurement method. Background Art

[0002] A fiber optic pressure sensor is a pressure detection device based on fiber optic sensing technology. Usually, by integrating a fiber grating or other sensitive elements into a specific design structure, the change of the output optical signal is monitored, so as to realize the perception of external pressure changes. Due to the advantages of miniaturization, high temperature resistance, and the ability to sense weak changes, fiber optic pressure sensors are currently widely used in fields such as aerospace, bridge monitoring, nuclear power equipment monitoring, and medical treatment.

[0003] Fiber optic pressure sensors are usually divided into two categories: one is the fiber optic pressure sensor based on fiber grating, which uses the fiber grating as the core sensitive element. When subjected to external force, it will cause the central reflection wavelength to shift, thereby indirectly measuring the magnitude of the external pressure. This fiber optic pressure sensor has strong anti-electromagnetic interference ability, but due to indirect measurement, it is easy to introduce errors during the transmission process and is extremely susceptible to temperature influence, resulting in its inability to work normally for a long time; the other is the fiber optic pressure sensor based on Fabry-Perot, whose main part is an air cavity formed by two flat and coaxial fiber end faces (or formed by one fiber end face and one diaphragm). The external pressure directly causes the cavity or diaphragm to deform, and then through the multi-beam interference principle of light, the high-precision measurement of the external pressure magnitude can be realized. In some special working environments, this fiber optic pressure sensor has better stability and accuracy than the fiber optic pressure sensor based on fiber grating. For example, the diaphragm-type fiber optic Fabry-Perot pressure sensor demodulates external parameters such as pressure or strain through the change of the cavity length value and has great potential in high-precision pressure measurement.

[0004] However, in high-temperature and high-pressure environments, such as ultra-deep oil and gas exploration environments, the application of the current diaphragm-type fiber optic Fabry-Perot pressure sensor is still limited and challenged, and it is difficult to perform long-term high-precision, high-sensitivity, and robust real-time monitoring tasks. There are mainly the following problems: First, when the temperature reaches 200 °C or even higher, the non-linear temperature drift (the phenomenon that the performance parameters of a device or component change non-linearly with temperature change) is one of the main factors causing measurement errors of the diaphragm-type fiber optic Fabry-Perot pressure sensor, seriously limiting the measurement accuracy; Second, when the pressure reaches 200 MPa or even higher, the interference microcavity structure of the diaphragm-type fiber optic Fabry-Perot pressure sensor is unstable, resulting in multi-physical field cross-coupling, seriously limiting the sensitivity and reliability; III. Under the long-term high-temperature and high-pressure environment, the creep phenomenon of the pressure-sensitive diaphragm is one of the main factors causing measurement errors in the diaphragm-type fiber optic Fabry-Perot pressure sensor, seriously limiting the measurement accuracy. IV. The pressure sensitivity and reliability of the diaphragm restrict each other, and it is necessary to solve the balance problem between the diaphragm sensitivity and the high failure threshold.

[0005] Therefore, how to enable the diaphragm-type fiber optic Fabry-Perot pressure sensor to meet the requirements of long-term high-precision monitoring in high-temperature and high-pressure environments is a technical problem that needs to be solved urgently for the efficient development of ultra-deep oil and gas and the development of sensing technology. Summary of the Invention

[0006] One of the purposes of the present invention is at least to provide a highly reliable pressure-separating and pressure-picking fiber optic pressure sensor and a measurement method to overcome the problems existing in the above-mentioned prior art. The sensor can achieve single pressure sensing of the diaphragm through the design of a pressure-separating cavity, greatly reduce the influence of temperature on the cavity length through a temperature self-compensation structure and a synchronous micro-cavity temperature compensation structure, meet different measurement ranges by reasonably designing the size parameters of the diaphragm, and suppress the creep problem by reasonably designing the thickness distribution of the diaphragm through stress homogenization. It has the advantages of large measurement range, high sensitivity, high measurement accuracy, high temperature and high pressure resistance, and long-term reliable and stable measurement, significantly improving the reliability and stability of the sensor.

[0007] To achieve the above purpose, the technical solutions adopted by the present invention include the following aspects.

[0008] A highly reliable pressure-separating and pressure-picking fiber optic pressure sensor includes a sensor component, and a first optical fiber, a second optical fiber, a temperature compensation boss and a diaphragm located inside the sensor component. The sensor component is in an overall cylindrical structure with both ends open. The sensor component includes a cylinder body, a fixing member and a closing member. The fixing member and the closing member are located inside the cylinder body. The cross-section of the cylinder body is in a circular ring shape. The cylinder body includes part one and part two. The inner diameter of part one is smaller than that of part two, and the outer diameter of part one is not less than that of part two. The fixing member is in a cylindrical structure with a groove-shaped cross-section. The diameter of the fixing member is larger than the inner diameter of part one and smaller than the inner diameter of part two. The fixing member is connected to part one and retains a certain distance from part two. The closing member is connected to the fixing member and also connected to part two. The fixing member is connected to the temperature compensation boss. The first optical fiber is arranged inside the temperature compensation boss. The fixing member is also connected to the second optical fiber. The second optical fiber and part one form a synchronous micro-cavity temperature compensation structure. The diaphragm is arranged inside part one and forms a Fabry-Perot cavity with the first optical fiber. The sensor component and the temperature compensation boss are made of heterogeneous materials and have a difference in thermal expansion coefficient, and the sensor component and the temperature compensation boss form a temperature self-compensation structure.

[0009] Preferably, the first end face of the first component is the first end face of the sensor component. The second end face of the first component is connected to the first end face of the second component, and the second end of the second component extends away from the first component. The first component and the second component are integrally formed.

[0010] Preferably, the top of the fixing member is connected to the second end face of the first component. When the fixing member is connected to the first component, a certain distance is reserved between the inner side wall three of the fixing member and the inner side wall one of the first component, and an inner plane is formed on the second end face of the first component. A certain distance is reserved between the outer side wall one of the fixing member and the inner side wall two of the second component. A central large through hole and an eccentric small through hole are provided at the bottom of the fixing member.

[0011] Preferably, the closing component is a cylindrical structure with a groove-shaped cross section. The closing component is arranged near the second end of the second component. The notch of the closing component is in the same orientation as the notch of the fixing member. The bottom of the fixing member is arranged in the groove of the closing component. The inner side wall four of the closing component is connected to the outer side wall one of the fixing member. The outer side wall two of the closing component is connected to the inner side wall two of the second component of the cylinder body. The cylinder body, the fixing member, and the closing component are integrally formed to form a pressure isolation cavity of the sensor. A through hole one and a through hole two are provided at the bottom of the groove of the closing component. The through hole one corresponds to the central large through hole on the fixing member, and the through hole two corresponds to the eccentric small through hole on the fixing member.

[0012] Preferably, the diaphragm is integrally formed with the inner side wall one of the first component or is fixedly connected by a heterogeneous connection process. The diaphragm is a stress-equalizing diaphragm.

[0013] Preferably, the cross section of the diaphragm is generally circular as a whole. The left and right sides of the diaphragm are curved surfaces that are close to each other. The diaphragm has a certain thickness, and the thickness of the diaphragm increases from the center to the edge.

[0014] Preferably, the temperature compensation boss is arranged at the central large through hole of the fixing member. The boss plane of the temperature compensation boss passes through the central large through hole. The boss plane is parallel to the diaphragm and a certain distance is reserved. A through hole passing through the temperature compensation boss is provided on the temperature compensation boss. The through hole is opened in a direction perpendicular to the boss plane of the temperature compensation boss.

[0015] Preferably, the first optical fiber is disposed in the through hole of the temperature compensation boss. One end face of the first optical fiber is the end face of the first end of the first optical fiber. The end face of the optical fiber is flush with the boss plane of the temperature compensation boss. The end face of the optical fiber is parallel and coaxial with the diaphragm, and a Fabry-Perot cavity is formed. The second end of the first optical fiber extends out of the through hole and extends away from the temperature compensation boss. The second optical fiber is disposed in the eccentric small through hole of the fixing member. One end face of the second optical fiber is the end face of the first end of the second optical fiber. The end face of the optical fiber is parallel to the inner plane of the first component, and a synchronous micro-cavity temperature compensation structure is formed. The second end of the second optical fiber extends out of the eccentric small through hole and extends away from the fixing member.

[0016] A measuring method of a highly reliable pressure-separating and pressure-picking fiber optic pressure sensor, based on the aforementioned highly reliable pressure-separating and pressure-picking fiber optic pressure sensor, includes the following steps: Step 1: Turn on the laser source, and transmit the optical signal output by the laser source to the ring coupler through the optical fiber. Step 2: The ring coupler distributes the received optical signal and transmits it to the highly reliable pressure-separating and pressure-picking fiber optic pressure sensor. Step 3: The optical signal is reflected and interfered multiple times in the highly reliable pressure-separating and pressure-picking fiber optic pressure sensor and then returns to the ring coupler. Step 4: The ring coupler guides the received reflected optical signal to the acquisition and demodulation module, and converts the reflected optical signal into an electrical signal through the acquisition and demodulation module. Step 5: The host computer uses the demodulation algorithm to analyze and process the electrical signal, and finally calculates the real-time cavity length value.

[0017] Preferably, in the step 3, the diaphragm in the sensor component senses the external pressure and deforms, and the deformation of the diaphragm causes changes in the optical field distribution and optical path difference of the Fabry-Perot cavity.

[0018] In summary, due to the adoption of the above technical solutions, the present invention has at least the following beneficial effects: 1. The highly reliable pressure-separating and pressure-picking fiber optic pressure sensor is simple to operate and has excellent performance. It can meet the urgent needs of long-term reliable and high-precision pressure measurement in high-temperature and high-pressure environments. By simultaneously measuring the cavity length value through the first optical fiber and the second optical fiber, the Fabry-Perot cavity formed by the first optical fiber and the diaphragm mainly completes the sensing and detection of the external pressure. The cavity length value corresponding to the second optical fiber is hardly affected by the pressure, and accurate temperature information can be obtained to realize synchronous micro-cavity temperature compensation and overcome the influence of high temperature on the diaphragm-type fiber optic Fabry-Perot pressure sensor. 2. The sensor component and the temperature compensation boss are made of heterogeneous materials, resulting in a difference in thermal expansion coefficient, forming a temperature self-compensation structure, which can avoid the significant influence of temperature on the cavity length value and enable the sensor to work stably in a wide temperature range (temperature range is 0 °C to 200 °C). 3. The diaphragm has the characteristic of uniform stress distribution, which can inhibit its creep process and enable the sensor to work reliably for a long time even in high-temperature and high-pressure environments. 4. The pressure isolation cavity ensures that the Fabry-Perot cavity will not be deformed due to external pressure, avoiding interference with the measurement results, thus realizing the single pressure sensing of the diaphragm. 5. According to different measurement requirements, the size parameters of the diaphragm are reasonably designed to make it suitable for the corresponding measurement environment and balance the pressure sensing sensitivity and measurement failure threshold of the diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of a highly reliable pressure isolation and pressure pickup type fiber optic pressure sensor according to an exemplary embodiment of the present invention.

[0020] Figure 2 is a three-dimensional structural diagram of a highly reliable pressure isolation and pressure pickup type fiber optic pressure sensor according to an exemplary embodiment of the present invention.

[0021] Figure 3 is Figure 1 an installation schematic diagram of the cylinder body, the fixing member and the closing member of

[0022] Figure 4 is a measurement schematic diagram of a highly reliable pressure isolation and pressure pickup type fiber optic pressure sensor according to an exemplary embodiment of the present invention.

[0023] Figure 5 is a measurement flow chart of a highly reliable pressure isolation and pressure pickup type fiber optic pressure sensor according to an exemplary embodiment of the present invention.

[0024] Reference numerals in the figures: 1 - sensor component, 11 - cylinder body, 111 - component one, 101 - inner side wall one, 102 - internal plane, 112 - component two, 103 - inner side wall two, 12 - fixing member, 121 - top, 122 - bottom, 123 - inner side wall three, 124 - outer side wall one, 13 - closing member, 131 - inner side wall four, 132 - outer side wall two, 2 - first optical fiber, 200 - optical fiber end face one, 3 - second optical fiber, 300 - optical fiber end face two, 4 - temperature compensation boss, 400 - boss plane, 5 - diaphragm, 6 - pressure isolation cavity, 7 - closing member, 71 - inner side wall four, 72 - outer side wall two. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to make the purpose, technical solution and advantages of the present invention clearer. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiment 1

[0026] This embodiment shows the structure of a highly reliable pressure isolation and pressure pickup type fiber optic pressure sensor, asFigure 1-2 As shown, it includes a sensor component 1, and a first optical fiber 2, a second optical fiber 3, a temperature compensation boss 4 and a diaphragm 5 located inside the sensor component 1. The sensor component 1 is integrally in a cylindrical structure with both ends open. The first optical fiber 2 and the second optical fiber 3 are used for simultaneously measuring the cavity length. The first optical fiber 2 is arranged inside the temperature compensation boss 4, and the second optical fiber 3 is connected to the sensor component 1. The temperature compensation boss 4 is connected to the sensor component 1. The diaphragm 5 is arranged on the sensor component 1 and is used for sensing the external pressure.

[0027] The sensor component 1 is preferably made of maraging steel (such as F141 maraging steel). The sensor component 1 includes a cylinder body 11, a fixing part 12 and a closing part 13. The cylinder body 11, the fixing part 12 and the closing part 13 are made of the same material and are integrally formed. The fixing part 12 and the closing part 13 are located inside the cylinder body 11.

[0028] The cross-section of the cylinder body 11 is in an annular shape. The cylinder body 11 includes a part one 111 and a part two 112. Both the part one 111 and the part two 112 are in a cylindrical structure. The inner diameter of the part one 111 is smaller than the inner diameter of the part two 112, and the outer diameter of the part one 111 is not less than the outer diameter of the part two 112. The first end face of the part one 111 is the first end face of the sensor component 1. The second end face of the part one 111 is connected to the first end face of the part two 112. The first end and the second end of the part one 111 are opposite. The second end of the part two 112 extends away from the part one 111. The first end and the second end of the part two 112 are opposite. The second end face of the part two 112 is the second end face of the sensor component 1. The first end and the second end of the sensor component 1 are opposite. The part one 111 and the part two 112 are integrally formed.

[0029] The fixing part 12 is in a cylindrical structure with a cross-section in a groove shape. The top 121 ( Figure 3 in the left-right direction) of the fixing part 12 is connected to the second end face of the part one 111. When the fixing part 12 is connected to the part one 111, a certain distance is reserved between the inner side wall three 123 of the fixing part 12 and the inner side wall one 101 of the part one 111, and an internal plane 102 is formed on the second end face of the part one 111. A certain distance is reserved between the outer side wall 124 of the fixing part 12 and the inner side wall two 103 of the part two 112. A central large through hole and an eccentric small through hole are opened at the bottom 122 of the fixing part 12. The central large through hole is coaxial with the diaphragm 5. The diameter of the central large through hole is larger than the diameter of the eccentric small through hole. A certain distance is reserved between the eccentric small through hole and the central large through hole, and it is close to the inner side wall three 123 of the fixing part 12.

[0030] The closed component 13 is a cylindrical structure with a groove-shaped cross-section. The closed component 13 is arranged at the second end close to the component two 112. The notch of the closed component 13 faces the same direction as the notch of the fixing part 12. The bottom 122 of the fixing part 12 is arranged at the groove of the closed component 13 (the bottom of the fixing part can be connected to the bottom of the groove of the closed component 13, or not connected, and there can also be a gap between the bottom of the fixing part and the bottom of the groove of the closed component). The inner side wall four 131 of the closed component 13 is connected to the outer side wall one 124 of the fixing part 12. The outer side wall two 132 of the closed component 13 is connected to the inner side wall two 103 of the component two 112 of the cylinder 11, so that the cylinder 11, the fixing part 12 and the closed component 13 form a closed cavity structure, which is the pressure isolation cavity 6 of the sensor. The pressure isolation cavity 6 is a pressure isolation area that can isolate the external pressure. The cylinder 11, the fixing part 12 and the closed component 13 are integrally formed. When the closed component 13 is connected to the cylinder 11 and the fixing part 12, brazing, bonding and other methods can also be used for connection, and good sealing performance needs to be ensured during connection. A through hole one and a through hole two are opened at the bottom of the groove of the closed component 13. The through hole one corresponds to the central large through hole on the fixing part 12, and the through hole two corresponds to the eccentric small through hole on the fixing part 12; In addition to Figure 1 the shown packaging structure, it can also be determined according to the design requirements. For example, a cylindrical structure with a circular ring cross-section is sleeved on the bottom 122 of the fixing part 12. The cylindrical structure is close to the second end of the component two 112 of the cylinder 11. The inner wall of the cylindrical structure is connected to the outer side wall one 124 of the fixing part 12, and the outer wall of the cylindrical structure is connected to the inner side wall two 103 of the component two 112 of the cylinder 11.

[0031] The diaphragm 5 is arranged on the cylinder 11 of the sensor component 1 and is located inside the component one 111 of the cylinder 11. The diaphragm 5 is connected to the inner side wall one 101 of the component one 111. The diaphragm 5 and the component one 111 are fixedly connected by a heterogeneous connection process (such as adhesive, brazing and other processes) (at this time, the diaphragm and the component one are heterogeneous materials). To prevent gas leakage, good sealing performance needs to be ensured during connection. As one of the preferred implementation modes, to avoid the possible leakage and deformation problems of the connection part in the split structure, the diaphragm 5 and the component one 111 are preferably integrally formed (at this time, the diaphragm and the component one are homogeneous materials); For different measurement range requirements, under the principle of taking into account sensitivity, reliability and increasing the failure threshold of the diaphragm 5, a diaphragm 5 with appropriate shape and size and stress homogenization is designed. For example, the cross-section of the diaphragm 5 is generally circular, and the left and right ( Figure 1On both sides in the left - right direction, the surfaces are curved surfaces that are close to each other (concave inward). The diaphragm 5 has a certain thickness. The thickness difference between the edge and the center of the diaphragm is 3 - 5 mm. The thickness transitions from the center of the diaphragm to the edge linearly or curvilinearly. The diaphragm thickness determines the sensitivity and reliability, and the sensitivity and reliability are determined according to the structural design parameters. The structural design parameters include the diaphragm shape, diaphragm size, and diaphragm thickness distribution. The design that the edge part of the diaphragm 5 is thicker than the center part enables the edge part to bear relatively more pressure loads, thereby reducing the stress concentration degree in the center part, making the stress evenly distributed on the diaphragm 5, thus inhibiting the failure of the diaphragm 5 due to creep and increasing the measurement failure threshold and pressure - sensing sensitivity of the diaphragm 5.

[0032] The temperature - compensating boss 4 is made of austenitic stainless steel (such as 304 austenitic stainless steel) or aluminum material. The cross - section of the temperature - compensating boss 4 is convex. The temperature - compensating boss 4 is arranged at the center large through - hole of the fixing part 12. The boss plane 400 of the temperature - compensating boss 4 passes through the center large through - hole, and the boss plane 400 is parallel to the diaphragm 5 and keeps a certain distance. A through - hole penetrating the temperature - compensating boss 4 is opened on the temperature - compensating boss 4, and the through - hole is opened along the direction perpendicular to the boss plane 400 of the temperature - compensating boss 4. The temperature - compensating boss 4 and the fixing part 12 are made of heterogeneous materials, and the temperature - compensating boss 4 and the fixing part 12 are fixedly connected by bonding or brazing. To prevent gas from escaping, good sealing must be ensured during connection.

[0033] The sensor component 1 and the temperature - compensating boss 4 are made of heterogeneous materials. When the temperature changes, due to the difference in thermal expansion coefficients between the sensor component 1 and the temperature - compensating boss 4, the deformation amounts generated by the two different materials are different. Assume that the thermal expansion coefficient of the material used for the sensor component 1 is and the thermal expansion coefficient of the material used for the temperature - compensating boss 4 is When the temperature change is , the change amount of the structural length of the sensor component 1 is ( is the initial structural length of the sensor component), and the change amount of the structural length of the temperature - compensating boss 4 is ( is the initial structural length of the temperature - compensating boss). By optimizing the structural dimensions of the two, is achieved to complete temperature self - compensation.

[0034] The first optical fiber 2 is disposed in the through hole of the temperature compensation boss 4. One end face 200 of the optical fiber of the first optical fiber 2 is the end face of the first end of the first optical fiber 2. The end face 200 of the optical fiber is flush with the boss plane 400 of the temperature compensation boss 4. The end face 200 of the optical fiber is parallel and coaxial with the diaphragm 5, and a Fabry-Perot cavity is formed. The second end of the first optical fiber 2 extends out of the through hole and extends in a direction away from the temperature compensation boss 4. The first end and the second end of the first optical fiber 2 are opposite to each other. The first optical fiber 2 and the temperature compensation boss 4 are made of heterogeneous materials. The first optical fiber 2 and the temperature compensation boss 4 are fixedly connected by bonding or brazing. To prevent gas from escaping, good sealing performance is required during connection.

[0035] The second optical fiber 3 is disposed in the eccentric small through hole of the fixing member 12. One end face 300 of the optical fiber of the second optical fiber 3 is the end face of the first end of the second optical fiber 3. The end face 300 of the optical fiber is parallel to the inner plane 102 of the first component 111, and a synchronous micro-cavity temperature compensation structure is formed. The second end of the second optical fiber 3 extends out of the eccentric small through hole and extends in a direction away from the fixing member 12. The first end and the second end of the second optical fiber 3 are opposite to each other. The second optical fiber 3 and the fixing member 12 are made of heterogeneous materials. The second optical fiber 3 and the fixing member 12 are fixedly connected by bonding or brazing. To prevent gas from escaping, good sealing performance is required during connection.

[0036] When the highly reliable pressure-isolating and pressure-sensing optical fiber pressure sensor works in a high-pressure environment, the pressure-isolating cavity 6 can isolate the external pressure, avoiding the deformation of the Fabry-Perot cavity and the synchronous micro-cavity temperature compensation structure caused by the external pressure. After the pressure-isolating cavity 6 isolates the external pressure, only the diaphragm 5 senses the external pressure, realizing the effect of single pressure sensing of the diaphragm 5. The cavity length value measured by the first optical fiber 2 includes the information of the external pressure and the environmental temperature change, and the cavity length value measured by the second optical fiber 3 only includes the information of the environmental temperature change. By combining the cavity length values measured by the first optical fiber 2 and the second optical fiber 3, the real-time cavity length value is finally calculated, overcoming the influence of high temperature on the sensor, thereby improving the measurement sensitivity and accuracy of the sensor. The highly reliable pressure-isolating and pressure-sensing optical fiber pressure sensor of the present invention can stably work in an environment with a temperature of 0 °C to 200 °C and a pressure of 0 Mpa to 200 Mpa, improving the measurement accuracy and reliability in a high-temperature and high-pressure environment; in an extreme high-temperature and high-pressure environment with a temperature greater than 200 °C and a pressure greater than 200 Mpa, the highly reliable pressure-isolating and pressure-sensing optical fiber pressure sensor of the present invention also has application potential. Embodiment 2

[0037] This embodiment shows the measurement method of the highly reliable pressure-isolating and pressure-sensing optical fiber pressure sensor. Figure 5 The measurement flow chart is shown. During the application process, a measurement system of the highly reliable pressure-isolating and pressure-sensing optical fiber pressure sensor can be built. Refer to Figure 4, The highly reliable pressure-separated and pressure-sensing fiber optic pressure sensor is located in the environment to be measured, and is connected to the ring coupler through the first optical fiber 2 and the second optical fiber 3. The ring coupler is connected to the laser source through an optical fiber, and the ring coupler is also connected to the acquisition and demodulation module. The acquisition and demodulation module is connected to the upper computer. The measurement method of the highly reliable pressure-separated and pressure-sensing fiber optic pressure sensor specifically includes the following steps: Step 1: Turn on the laser source, and transmit the optical signal output by the laser source to the ring coupler through the optical fiber; Step 2: The ring coupler distributes the received optical signal and transmits it to the highly reliable pressure-separated and pressure-sensing fiber optic pressure sensor. The ring coupler transmits the optical signal to the inside of the sensor component 1 of the highly reliable pressure-separated and pressure-sensing fiber optic pressure sensor through the first optical fiber 2 and the second optical fiber 3; Step 3: The optical signal undergoes multiple reflections and interferences in the highly reliable pressure-separated and pressure-sensing fiber optic pressure sensor and then is transmitted back to the ring coupler. The diaphragm 5 in the sensor component 1 senses the external pressure and deforms. The deformation of the diaphragm 5 causes changes in the optical field distribution and optical path difference of the Fabry-Perot cavity. The change in the optical field distribution causes the propagation path of light in the Fabry-Perot cavity to change, and the change in the optical path difference directly affects the movement of the interference fringes, thus providing a basis for subsequent pressure measurement; The first optical fiber 2 and the second optical fiber 3 are used to transmit the reflected optical signal back to the ring coupler. The first optical fiber 2 transmits the optical signal reflected by the Fabry-Perot cavity, and the second optical fiber 3 transmits the optical signal reflected by the synchronous micro-cavity temperature compensation structure; Step 4: The ring coupler guides the received reflected optical signal to the acquisition and demodulation module, and converts the reflected optical signal into an electrical signal through the acquisition and demodulation module; Step 5: The upper computer uses the demodulation algorithm to analyze and process the electrical signal, and finally calculates the real-time cavity length value.

[0038] As described above, it is only a detailed description of the specific implementation manner of the present invention, rather than a limitation of the present invention. Various substitutions, variations, and improvements made by those skilled in the relevant technical fields without departing from the principles and scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly reliable diaphragm-separated and pressure-picking fiber optic pressure sensor, characterized in that, Comprising: A sensor component (1), and a first optical fiber (2), a second optical fiber (3), a temperature compensation boss (4) and a diaphragm (5) located inside the sensor component (1). The sensor component (1) is integrally in a cylindrical structure with both ends open. The sensor component (1) includes a cylinder body (11), a fixing member (12) and a closing member (13). The fixing member (12) and the closing member (13) are located inside the cylinder body (11). The cross-section of the cylinder body (11) is in an annular shape. The cylinder body (11) includes a part one (111) and a part two (112). The inner diameter of the part one (111) is smaller than the inner diameter of the part two (112), and the outer diameter of the part one (111) is not less than the outer diameter of the part two (112). The fixing member (12) is in a cylindrical structure with a groove-shaped cross-section. The diameter of the fixing member (12) is larger than the inner diameter of the part one (111) and smaller than the inner diameter of the part two (112). The fixing member (12) is connected to the part one (111) and has a certain distance from the part two (112). The closing member (13) is connected to the fixing member (12) and also to the part two (112). The fixing member (12) is connected to the temperature compensation boss (4). The first optical fiber (2) is arranged inside the temperature compensation boss (4). The fixing member (12) is also connected to the second optical fiber (3). The second optical fiber (3) and the part one (111) form a synchronous microcavity temperature compensation structure. The diaphragm (5) is arranged inside the part one (111) and forms a Fabry-Perot cavity with the first optical fiber (2). The sensor component (1) and the temperature compensation boss (4) are made of heterogeneous materials and have a difference in thermal expansion coefficient. The sensor component (1) and the temperature compensation boss (4) form a temperature self-compensation structure.

2. The highly reliable diaphragm pressure pickup type fiber optic pressure sensor according to claim 1, wherein The first end face of the part one (111) is the first end face of the sensor component (1). The second end face of the part one (111) is connected to the first end face of the part two (112). The second end of the part two (112) extends in a direction away from the part one (111). The part one (111) and the part two (112) are integrally formed.

3. The highly reliable diaphragm pressure pick-up type fiber optic pressure sensor according to claim 2, characterized in that The top (121) of the fixing member (12) is connected to the second end face of the part one (111). When the fixing member (12) is connected to the part one (111), a certain distance is reserved between the inner side wall three (123) of the fixing member (12) and the inner side wall one (101) of the part one (111), and an internal plane (102) is formed on the second end face of the part one (111). A certain distance is reserved between the outer side wall one (124) of the fixing member (12) and the inner side wall two (103) of the part two (111). A central large through-hole and an eccentric small through-hole are provided at the bottom (122) of the fixing member (12).

4. The highly reliable diaphragm-separated pressure-sensing fiber optic pressure sensor according to claim 1, wherein, The closed component (13) has a cylindrical structure with a groove-shaped cross-section. The closed component (13) is arranged near the second end of the second component (112). The notch of the closed component (13) faces the same direction as the notch of the fixing member (12). The bottom (122) of the fixing member (12) is arranged at the groove of the closed component (13). The inner side wall four (131) of the closed component (13) is connected to the outer side wall one (124) of the fixing member (12). The outer side wall two (132) of the closed component (13) is connected to the inner side wall two (103) of the second component (112) of the cylinder body (11). The cylinder body (11), the fixing member (12) and the closed component (13) are integrally formed to form a pressure isolation cavity (6) of the sensor. A through hole one and a through hole two are provided at the bottom of the groove of the closed component (13). The through hole one corresponds to the central large through hole on the fixing member (12), and the through hole two corresponds to the eccentric small through hole on the fixing member (12).

5. The highly reliable diaphragm pressure pick-up type fiber optic pressure sensor according to claim 3, characterized in that, The diaphragm (5) is integrally formed with the inner side wall one (101) of the first component (111) or is fixedly connected by a heterogeneous connection process. The diaphragm (5) is a stress-equalizing diaphragm.

6. The highly reliable pressure-isolated and pressure-sensing fiber optic pressure sensor according to claim 5, wherein The cross-section of the diaphragm (5) is generally circular as a whole. The left and right sides of the diaphragm (5) are curved surfaces close to each other. The diaphragm (5) has a certain thickness, and the thickness of the diaphragm (5) increases from the center to the edge.

7. The highly reliable diaphragm-separated pressure-sensing fiber optic pressure sensor according to claim 3, wherein The temperature compensation boss (4) is arranged at the central large through hole of the fixing member (12). The boss plane (400) of the temperature compensation boss (4) passes through the central large through hole. The boss plane (400) is parallel to the diaphragm (5) and maintains a certain distance. A through hole passing through the temperature compensation boss (4) is provided on the temperature compensation boss (4). The through hole is arranged along the direction perpendicular to the boss plane (400) of the temperature compensation boss (4).

8. The highly reliable diaphragm-separated pressure-sensing optical fiber pressure sensor according to claim 7, characterized in that, The first optical fiber (2) is arranged in the through hole of the temperature compensation boss (4). The optical fiber end face one (200) of the first optical fiber (2) is the end face of the first end of the first optical fiber (2). The optical fiber end face one (200) is flush with the boss plane (400) of the temperature compensation boss (4). The optical fiber end face one (200) is parallel and coaxial with the diaphragm (5) to form a Fabry-Perot cavity. The second end of the first optical fiber (2) extends out of the through hole and extends in a direction away from the temperature compensation boss (4). The second optical fiber (3) is arranged in the eccentric small through hole of the fixing member (12). The optical fiber end face two (300) of the second optical fiber (3) is the end face of the first end of the second optical fiber (3). The optical fiber end face two (300) is parallel to the inner plane (102) of the first component (111) to form a synchronous micro-cavity temperature compensation structure. The second end of the second optical fiber (3) extends out of the eccentric small through hole and extends in a direction away from the fixing member (12).

9. A measurement method for a highly reliable pressure-separated and pressure-pickup optical fiber pressure sensor, characterized in that, Based on the highly reliable pressure isolation and pressure pickup type optical fiber pressure sensor according to any one of claims 1 to 8, the following steps are included: Step 1, turn on the laser source, and transmit the optical signal output by the laser source to the ring coupler through the optical fiber. Step 2, the ring coupler distributes the received optical signal and transmits it to the highly reliable pressure isolation and pressure pickup type optical fiber pressure sensor. Step 3: The optical signal undergoes multiple reflections and interferences inside the highly reliable pressure-isolating and pressure-sensing fiber optic pressure sensor and then is transmitted back to the ring coupler; Step 4: The ring coupler guides the received reflected optical signal to the acquisition and demodulation module, and the reflected optical signal is converted into an electrical signal through the acquisition and demodulation module; Step 5: The host computer uses a demodulation algorithm to analyze and process the electrical signal, and finally calculates the real-time cavity length value.

10. The measurement method of the highly reliable pressure-isolated and pressure-sensing optical fiber pressure sensor according to claim 9, wherein, In the said Step 3, the diaphragm (5) inside the sensor component (1) senses the external pressure and deforms, and the deformation of the diaphragm (5) causes changes in the optical field distribution and optical path difference of the Fabry-Perot cavity.

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