Fluid pressure sensor

Abstract

The utility model discloses a fluid pressure sensor, which comprises a cylindrical shell, one end of the shell is provided with an incident optical fiber in coaxial sealing connection, the other end of the shell is provided with an optical channel arranged along the axial direction in a penetrating manner, one end of the optical channel is connected with the incident optical fiber, and the other end of the optical channel is connected with the optical fiber. A transmission sheet and a reflection sheet which are arranged in a closed manner are arranged at the end part of the other end, the reflection sheet is positioned on one side, far away from the incident optical fiber, of the transmission sheet, and a Fabry-Perot cavity is formed between the transmission sheet and the reflection sheet; the end, away from the incident optical fiber, of the shell is covered with a protective cap with the closed end, a detection cavity is formed between the protective cap and the end of the shell, and a circulation hole is formed in the protective cap in the radial direction and communicated with the detection cavity. The device has the advantages of being reasonable in structural design, capable of reducing impurity impact, beneficial to guaranteeing detection accuracy, prolonging service life and the like.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and in particular to a fluid pressure sensor. Background Technology

[0002] Fiber optic sensing is a crucial application of modern fiber optic technology, boasting advantages such as small size, simple structure, high sensitivity, strong resistance to electromagnetic interference, and long-distance transmission. It can be used to detect various physical quantities, including strain, temperature, pressure, sound field, electric field, vibration, and acceleration. Fiber optic Fabry-Perot sensors are one such example, widely used in real-time health monitoring of large engineering structures such as bridges, balance structures, and oil pipelines. During the extraction of fluids like gas and oil, pressure monitoring is necessary. Solid impurities often embedded in these fluids can cause impacts, and these instantaneous impacts can not only affect the accuracy of the detection but also damage the sensing end of the fiber optic sensor, shortening its lifespan. Utility Model Content

[0003] In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is: how to provide a fluid pressure sensor with a reasonable structural design that can reduce the impact of impurities, and help ensure detection accuracy and extend service life.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A fluid pressure sensor includes a cylindrical housing. One end of the housing has a coaxially sealed incident optical fiber, and the other end has an axially extending optical channel. One end of the optical channel is connected to the incident optical fiber, and the other end has a closed-off transmissive plate and a reflective plate. The reflective plate is located on the side of the transmissive plate away from the incident optical fiber, and an enamel cavity is formed between the two. The end of the housing away from the incident optical fiber is covered with a protective cap that is closed at the end. A detection cavity is formed between the protective cap and the end of the housing. A flow hole is radially provided on the protective cap and communicates with the detection cavity.

[0006] During detection, fluid enters the detection chamber through the flow hole, applying pressure to the reflector. The reflector deforms, changing the length of the enamel cavity, thus measuring the fluid pressure. In this structure, because the transmissive and reflective plates are located at the ends of the housing, and these ends are covered by end-sealed protective caps, solid impurities in the fluid cannot directly impact the reflector. This allows the reflector to detect fluid pressure more stably and reliably, resulting in more accurate results. Simultaneously, it prevents solid impurities from impacting the reflector and damaging the sensor, extending its service life.

[0007] Furthermore, multiple flow holes are evenly distributed along the circumference of the protective cap.

[0008] In this way, fluid can enter the detection chamber better through multiple flow holes, and the probability of flow holes being blocked can be reduced, ensuring reliable detection.

[0009] Furthermore, a collimating lens is disposed between the incident optical fiber and the optical channel, with the incident end of the incident optical fiber close to the collimating lens.

[0010] In this way, by setting a collimating lens in the optical channel, the optical fiber introduced by the incident optical fiber can be corrected into a parallel beam and sent to the transmission plate along the optical channel. This allows for a longer distance between the transmission plate and the incident optical fiber, which can keep the incident optical fiber away from the high-temperature environment when the end where the protective cap is located is inserted into the high-temperature detection environment, thus enhancing the environmental adaptability of the sensor.

[0011] Furthermore, the housing includes a front housing and a rear housing connected coaxially and sealed. The incident optical fiber is sealed and buried in the rear housing, and the optical channel is disposed through the front housing. The front housing or the rear housing has a receiving cavity coaxially arranged with the optical channel, and the receiving cavity is located at the connection end of the front housing and the rear housing. The diameter of the collimating lens matches the inner diameter of the receiving cavity and is disposed in the receiving cavity.

[0012] Furthermore, the end of the front housing or the rear housing has a coaxially arranged threaded hole, and the end face has a coaxially arranged annular sealing flange or annular sealing groove; the end of the rear housing or the front housing has a threaded shaft segment that matches the threaded hole, and the shoulder surface at the root of the threaded shaft segment has an annular sealing groove or annular sealing flange that is directly opposite to the annular sealing flange or annular sealing groove; the annular sealing flange and the corresponding annular sealing groove are in a sealing fit when the threaded shaft segment is connected to the threaded hole.

[0013] Furthermore, the threaded shaft section is located on the front housing, the receiving cavity is located inside the threaded shaft section, and a plunger is plugged at the end. The plunger has a coaxially through optical fiber hole, and the end of the incident optical fiber is disposed in the optical fiber hole.

[0014] Furthermore, the connection between the front housing and the rear housing is sealed by circumferential welding.

[0015] In this way, a secondary seal can be formed by circumferential welding, in addition to the primary seal formed by the annular sealing flange and the annular sealing groove, making the sealing effect of the shell more reliable.

[0016] Furthermore, the end of the housing opposite to the protective cap has a tapered threaded hole coaxially arranged with the optical channel, and an optical fiber sleeve is threaded onto the tapered threaded hole, with the incident optical fiber coaxially passing through the optical fiber sleeve; the bottom of the tapered threaded hole is coaxially provided with an optical fiber positioning hole communicating with the optical channel, and the incident optical fiber passes through the optical fiber positioning hole coaxially and sealingly, with the bottom of the tapered threaded hole filled with sealing material squeezed by the optical fiber sleeve.

[0017] Furthermore, the outer end of the tapered threaded hole has a filling cavity with a large diameter, and a sealing cap is fitted on the optical fiber sleeve. The sealing cap is threadedly connected to the housing and is sealed and welded to the housing and the optical fiber sleeve. The filling cavity is filled with sealing material.

[0018] Furthermore, a grating is etched on the incident optical fiber; a support plate is provided between the transmission plate and the reflection plate, the thickness of the support plate being consistent with the initial cavity length of the Fabry-Perot cavity; and a through hole is provided in the middle of the support plate.

[0019] By using the thickness of the support sheet to control the initial Fabry-Perot cavity length between the transmissive and reflective sheets, better product consistency can be achieved.

[0020] In summary, this utility model has the advantages of reasonable structural design, which can reduce the impact of impurities, and helps to ensure detection accuracy and extend service life. Attached Figure Description

[0021] Figure 1 This is a cross-sectional structural diagram of this embodiment.

[0022] Figure 2 for Figure 1 An enlarged structural diagram of the protective cap section. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the embodiments.

[0024] In practical implementation: such as Figure 1 and Figure 2As shown, a fluid pressure sensor includes a cylindrical housing 1. One end of the housing 1 has a coaxially sealed incident optical fiber 3, and the other end has an axially extending optical channel 2. One end of the optical channel 2 is connected to the incident optical fiber 3, and the other end has a closed-off transmission plate 4 and a reflective plate 5. The reflective plate 5 is located on the side of the transmission plate 4 away from the incident optical fiber 3, and an enamel cavity is formed between them. The end of the housing 1 away from the incident optical fiber 3 is covered with a protective cap 6 with an end-closed design. A detection cavity is formed between the protective cap 6 and the end of the housing 1. A flow hole 7 is radially arranged on the protective cap 6 and communicates with the detection cavity. Multiple flow holes 7 are evenly distributed around the circumference of the protective cap 6. A grating is etched on the incident optical fiber 3, allowing the sensor to simultaneously measure the ambient temperature.

[0025] A collimating lens 8 is disposed between the incident optical fiber 3 and the optical channel 2, with the incident end of the incident optical fiber 3 close to the collimating lens 8, which is a spherical lens. By placing a collimating lens in the optical channel, the optical fiber introduced by the incident optical fiber can be corrected into a parallel beam and sent along the optical channel to the transmission plate. This allows for a longer distance between the transmission plate and the incident optical fiber, enabling the incident optical fiber to be kept away from high-temperature environments, even when the end of the protective cap is inserted into a high-temperature detection environment, thus enhancing the sensor's environmental adaptability.

[0026] In this embodiment, the transmissive sheet 4 is a sapphire sheet; however, it can also be made of other high-temperature resistant transparent materials. The reflective sheet 5 is a reflective cover plate that covers the outside of the housing 1. The reflective cover plate can sense external pressure, thereby changing the Fabry-Perot cavity length between the reflective cover plate and the transmissive sheet to detect the pressure.

[0027] To control the initial length of the Fabry-Perot cavity between the reflector 5 and the transmissor 4, such as Figure 2 As shown, a support plate is provided between the transmissive plate 4 and the reflective plate 5, and the thickness of the support plate is consistent with the initial cavity length of the Fabry-Perot cavity; the support plate has a through hole in the middle. To adapt to high-temperature environments, the support plate is made of metal.

[0028] In operation, the light emitted from the incident fiber is collimated by a spherical lens into parallel light with a very small diameter (approximately 0.3 mm). This parallel light propagates forward, passes through the sapphire sheet, and is reflected by a reflective cover plate. The reflective cover plate and the upper surface of the sapphire sheet form an enamel cavity. During detection, fluid can enter the detection cavity through a flow hole, thus applying pressure to the reflective sheet. This causes a change in the distance between the reflective surface of the sheet and the sapphire surface (enamel cavity). The magnitude of the force on the cover plate is measured by measuring this change in distance. Because the transmissive and reflective sheets are located at the ends of the housing, and these ends are covered by end-sealed protective caps, solid impurities in the fluid cannot directly impact the reflective sheets. This allows the reflective sheets to detect fluid pressure more stably and reliably, resulting in more accurate detection results. Furthermore, it prevents solid impurities from impacting the reflective sheets and damaging the sensor, thus extending its service life.

[0029] The housing 1 includes a front housing 11 and a rear housing 12 coaxially and sealed together. The incident optical fiber 3 is sealed and embedded in the rear housing 12, and the optical channel 2 is disposed through the front housing 11. The front housing 11 or the rear housing 12 has a receiving cavity 13 coaxially arranged with the optical channel 2. The receiving cavity 13 is located at the connection end of the front housing 11 and the rear housing 12. The diameter of the collimating lens 8 matches the inner diameter of the receiving cavity 13 and is disposed in the receiving cavity 13.

[0030] In this embodiment, the rear housing 12 has a coaxially arranged threaded hole at its end and a coaxially arranged annular sealing flange on its end face; the front housing 11 has a threaded shaft section at its end that matches the threaded hole, and an annular sealing groove is provided on the shoulder surface at the root of the threaded shaft section, which is directly opposite to the annular sealing flange; the receiving cavity 13 is located inside the threaded shaft section, and a plunger 14 is inserted at its end, with a coaxially through optical fiber hole on the plunger 14, and the end of the incident optical fiber 3 is disposed in the optical fiber hole. The annular sealing flange and the corresponding annular sealing groove are sealed together when the threaded shaft section is connected to the threaded hole, and the connection between the front housing 11 and the rear housing 12 is sealed by circumferential welding. In this way, a secondary seal can be formed by circumferential welding in addition to the primary seal formed by the annular sealing flange and the annular sealing groove, making the sealing effect of the housing more reliable.

[0031] The housing 1 has a tapered threaded hole 15 coaxially arranged with the optical channel 2 at one end away from the protective cap 6. An optical fiber sleeve 9 is threaded onto the tapered threaded hole 15, and the incident optical fiber 3 is coaxially inserted into the optical fiber sleeve 9. The bottom of the tapered threaded hole 15 is coaxially provided with an optical fiber positioning hole that communicates with the optical channel 2. The incident optical fiber 3 passes through the optical fiber positioning hole in a sealed manner, and the bottom of the tapered threaded hole 15 is filled with a sealing material that is squeezed by the optical fiber sleeve 9.

[0032] Meanwhile, the outer end of the tapered threaded hole 15 has a filling cavity 16 with a large diameter. A sealing cap 17 is fitted on the optical fiber sleeve 9. The sealing cap 17 is threadedly connected to the housing 1 and is sealed and welded to the housing 1 and the optical fiber sleeve 9. The filling cavity 16 is filled with sealing material.

[0033] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A fluid pressure sensor, characterized in that, The device includes a cylindrical housing (1), one end of which has an incident optical fiber (3) connected coaxially and sealed, and the other end has an axially penetrating optical channel (2). One end of the optical channel (2) is connected to the incident optical fiber (3), and the other end has a closed-off transmission plate (4) and a reflection plate (5). The reflection plate (5) is located on the side of the transmission plate (4) away from the incident optical fiber (3), and an enamel cavity is formed between the two. The end of the housing (1) away from the incident optical fiber (3) is covered with a protective cap (6) with an end closed. A detection cavity is formed between the protective cap (6) and the end of the housing (1). A flow hole (7) is provided on the protective cap (6) in the radial direction and penetrates the detection cavity.

2. The fluid pressure sensor as described in claim 1, characterized in that, Multiple flow holes (7) are evenly distributed along the circumference of the protective cap (6).

3. The fluid pressure sensor as described in claim 1, characterized in that, A collimating lens (8) is provided between the incident optical fiber (3) and the optical channel (2), and the incident end of the incident optical fiber (3) is close to the collimating lens (8).

4. The fluid pressure sensor as described in claim 3, characterized in that, The housing (1) includes a front housing (11) and a rear housing (12) connected coaxially and sealed. The incident optical fiber (3) is sealed and buried in the rear housing (12). The optical channel (2) is disposed through the front housing (11). The front housing (11) or the rear housing (12) has a receiving cavity (13) coaxially arranged with the optical channel (2). The receiving cavity (13) is located at the connection end of the front housing (11) and the rear housing (12). The diameter of the collimating lens (8) matches the inner diameter of the receiving cavity (13) and is disposed in the receiving cavity (13).

5. The fluid pressure sensor as described in claim 4, characterized in that, The front housing (11) or the rear housing (12) has a threaded hole coaxially arranged at its end, and an annular sealing flange or annular sealing groove coaxially arranged on its end face; the rear housing (12) or the front housing (11) has a threaded shaft segment that matches the threaded hole at its end, and an annular sealing groove or annular sealing flange that is directly opposite the annular sealing flange or annular sealing groove on the shoulder surface at the root of the threaded shaft segment; the annular sealing flange and the corresponding annular sealing groove are sealed together when the threaded shaft segment is connected to the threaded hole.

6. The fluid pressure sensor as described in claim 5, characterized in that, The threaded shaft section is located on the front housing (11), the receiving cavity (13) is located inside the threaded shaft section, and the end is plugged with a plug (14). The plug (14) has a coaxially through optical fiber hole, and the end of the incident optical fiber (3) is located inside the optical fiber hole.

7. The fluid pressure sensor as described in claim 5, characterized in that, The connection between the front housing (11) and the rear housing (12) is sealed by circumferential welding.

8. The fluid pressure sensor as described in claim 1, characterized in that, The housing (1) has a tapered threaded hole (15) coaxially arranged with the optical channel (2) at one end away from the protective cap (6). An optical fiber sleeve (9) is threaded onto the tapered threaded hole (15), and the incident optical fiber (3) is coaxially inserted into the optical fiber sleeve (9). The bottom of the tapered threaded hole (15) is coaxially arranged with an optical fiber positioning hole that communicates with the optical channel (2). The incident optical fiber (3) passes through the optical fiber positioning hole in a sealed manner. The bottom of the tapered threaded hole (15) is filled with a sealing material that is squeezed by the optical fiber sleeve (9).

9. The fluid pressure sensor as described in claim 8, characterized in that, The outer end of the tapered threaded hole (15) has a large-diameter filling cavity (16), and a sealing cap (17) is fitted on the optical fiber sleeve (9). The sealing cap (17) is threadedly connected to the housing (1) and sealed and welded to the housing (1) and the optical fiber sleeve (9). The filling cavity (16) is filled with sealing material.

10. The fluid pressure sensor as claimed in claim 1, characterized in that, The incident optical fiber (3) is engraved with a grating; a support plate is provided between the transmission plate (4) and the reflection plate (5), the thickness of the support plate being consistent with the initial cavity length of the Fabry cavity; the support plate has a through hole in the middle.

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