An optical fiber acoustic sensor

Abstract

The application discloses an optical fiber sound sensor, which comprises a support, a mandrel installed on the support, and a sound-measuring optical fiber wound on the outer peripheral wall of the mandrel, wherein the outer peripheral wall of the mandrel is provided with a sensitivity-enhancing protrusion protruding towards the radial outside of the mandrel, the maximum distance of the sensitivity-enhancing protrusion to the axis of the mandrel is L1, the minimum radius of the mandrel is L2, and the following condition is met: 0.2mm<=L1-L2<=5mm. The optical fiber sound sensor can effectively enhance the coupling capacity between sound waves and the sound-measuring optical fiber by arranging the sensitivity-enhancing protrusion on the outer peripheral wall of the mandrel and limiting the difference between the maximum distance of the sensitivity-enhancing protrusion to the axis of the mandrel and the minimum radius of the mandrel, thereby improving the sensitivity of the optical fiber sound sensor in detecting sound wave signals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber sensing, and particularly to an optical fiber sound sensor. BACKGROUND

[0002] Optical fiber sensing is a technology that uses optical fibers as sensors to detect and measure external environmental physical quantities (such as temperature, pressure, strain, vibration, sound waves, chemical composition, etc.). Optical fibers have advantages such as anti-electromagnetic interference, corrosion resistance, and distributed detection, and are widely used in oil and gas resource exploration, submarine earthquake monitoring, and infrastructure safety diagnosis. In practical applications, not only is it necessary to detect sound waves with high sensitivity, but it is also often necessary to accurately monitor the environmental temperature to meet the needs of multi-parameter measurement in complex environments. Due to the high Young's modulus characteristics of optical fibers, their response to sound waves is relatively weak, which restricts the ability of optical fiber sensing systems to detect sound waves, resulting in low sensitivity of optical fiber sensing systems to detect sound wave signals. SUMMARY

[0003] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes an optical fiber sound sensor, which can effectively enhance the coupling ability between sound waves and sound-measuring optical fibers by providing a sensitivity-enhancing protrusion on the outer peripheral wall of the mandrel, thereby significantly improving the sensitivity of the optical fiber sound sensor to detect sound wave signals.

[0004] The optical fiber sound sensor according to the embodiments of the present application comprises a support, a mandrel installed on the support, and a sound-measuring optical fiber wound on the outer peripheral wall of the mandrel. The outer peripheral wall of the mandrel is provided with a sensitivity-enhancing protrusion protruding towards the radial outside of the mandrel. The maximum distance of the sensitivity-enhancing protrusion to the axis of the mandrel is L1, and the minimum radius of the mandrel is L2, and it is satisfied that 0.2mm≤L1-L2≤5mm.

[0005] The optical fiber sound sensor according to the embodiments of the present application can effectively enhance the coupling ability between sound waves and sound-measuring optical fibers by providing a sensitivity-enhancing protrusion on the outer peripheral wall of the mandrel and limiting the difference between the maximum distance of the sensitivity-enhancing protrusion to the axis of the mandrel and the minimum radius of the mandrel, thereby significantly improving the sensitivity of the optical fiber sound sensor to detect sound wave signals.

[0006] The optical fiber sound sensor according to some embodiments of the present application is provided with a plurality of sensitivity-enhancing protrusions, and the plurality of sensitivity-enhancing protrusions are arranged around the circumference of the mandrel.

[0007] The optical fiber sound sensor according to some embodiments of the present application is provided with a plurality of sensitivity-enhancing protrusions, and the plurality of sensitivity-enhancing protrusions are arranged around the circumference of the mandrel.

[0008] The optical fiber acoustic sensor according to some embodiments of the present application, the mandrel is configured as a tubular structure, the sensitivity-enhancing protrusions extend along the axial direction of the mandrel, and a plurality of the sensitivity-enhancing protrusions are connected in sequence to form the wall of the tubular structure.

[0009] The optical fiber acoustic sensor according to some embodiments of the present application, the wall thickness at the connection between two adjacent sensitivity-enhancing protrusions is less than the thickness of the sensitivity-enhancing protrusions in the thickness direction of the wall.

[0010] The optical fiber acoustic sensor according to some embodiments of the present application, the number of the sensitivity-enhancing protrusions is positively correlated with the sensitivity of the acoustic measurement fiber; and / or the radius of the mandrel is positively correlated with the sensitivity of the acoustic measurement fiber; and / or the wall thickness of the mandrel is negatively correlated with the sensitivity of the acoustic measurement fiber.

[0011] The optical fiber acoustic sensor according to some embodiments of the present application, the sensitivity-enhancing protrusions comprise at least one of a corrugated shape and a polygonal shape.

[0012] The optical fiber acoustic sensor according to some embodiments of the present application, further comprising a mounting frame connected to the support and extending along the radial direction of the mandrel, and one end of the mandrel is connected to the mounting frame.

[0013] The optical fiber acoustic sensor according to some embodiments of the present application, further comprising a damping structure mounted to the mounting frame, and the mandrel is mounted to the damping structure.

[0014] The optical fiber acoustic sensor according to some embodiments of the present application, further comprising a connecting sheet connected between the damping structure and the mandrel; wherein the connecting sheet is provided with a plurality of first connecting sites and a plurality of second connecting sites, the plurality of first connecting sites are distributed along a first direction and used to be connected to the damping structure, the plurality of second connecting sites are distributed along a second direction and used to be connected to the mandrel, and the first direction and the second direction intersect and both extend along the radial direction of the mandrel.

[0015] The optical fiber acoustic sensor according to some embodiments of the present application, the distance from the first connecting sites to the axis of the mandrel is less than the distance from the second connecting sites to the axis of the mandrel.

[0016] The optical fiber acoustic sensor according to some embodiments of the present application, the support comprises a base and an upper cover, the base and the upper cover are connected to define a mounting space, the mandrel is located in the mounting space, and the upper cover is provided with an acoustic measurement hole in communication with the mounting space.

[0017] According to some embodiments of the present application, the sound measuring holes are provided in plurality, and the plurality of sound measuring holes are distributed along the axial direction of the mandrel; wherein the upper cover is provided with a matching groove for winding the connecting rope, and the matching groove is arranged between two adjacent sound measuring holes.

[0018] According to some embodiments of the present application, the upper cover is provided with a mounting groove for accommodating at least part of the temperature measuring optical fiber.

[0019] Additional aspects and advantages of the present application will be in part apparent and in part pointed out below. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0021] Figure 1 Schematic diagram of the fiber optic sound sensor of some embodiments of the present application Figure 1 ;

[0022] Figure 2 Schematic diagram of the fiber optic sound sensor of some embodiments of the present application Figure 2 ;

[0023] Figure 3 Exploded view of the fiber optic sound sensor of some embodiments of the present application

[0024] Figure 4 Cross-sectional view of the fiber optic sound sensor of some embodiments of the present application

[0025] Figure 5 Schematic diagram of the mandrel of some embodiments of the present application Figure 1 ;

[0026] Figure 6 Schematic diagram of the mandrel of some embodiments of the present application Figure 2 ;

[0027] Figure 7 Comparison chart of the sensitivity of the corrugated hollow cylindrical mandrel and the non-corrugated cylindrical mandrel of the present application

[0028] Figure 8 Time-frequency chart of the unmanned aerial vehicle measured by the corrugated hollow cylindrical mandrel and the time-frequency chart of the unmanned aerial vehicle measured by the non-corrugated cylindrical mandrel of some embodiments of the present application

[0029] Figure 9 Assembly diagram of the base and the mandrel of some embodiments of the present application

[0030] Figure 10A schematic view of a base for some embodiments of the present application;

[0031] Figure 11 A schematic view of an upper cover for some embodiments of the present application;

[0032] Figure 12 A schematic view of a plurality of fiber optic acoustic sensor array arrangement for some embodiments of the present application.

[0033] Reference signs:

[0034] Fiber optic acoustic sensor 100; mounting rod 200;

[0035] Support 10; base 11, fiber winding disc 111; shelter eave 112; first threaded groove 113;

[0036] Upper cover 12; sound measuring hole 121; matching groove 122; mounting groove 123;

[0037] Second threaded groove 124; reinforcing rib 125; mounting space 20;

[0038] Spindle 30; sensitizing protrusion 31; thinning area 32; threaded groove 40; mounting frame 50;

[0039] Damping structure 60; connecting sheet 70; first connecting site 71, second connecting site 72. DETAILED DESCRIPTION

[0040] In order to better understand the technical solutions provided by the embodiments of the present specification, the technical solutions of the embodiments of the present specification will be described in detail below through the accompanying drawings and specific embodiments. It should be understood that the specific features in the embodiments of the present specification and the embodiments are detailed descriptions of the technical solutions of the embodiments of the present specification, and are not limitations of the technical solutions of the present specification. In the case of no conflict, the technical features in the embodiments of the present specification and the embodiments can be combined with each other.

[0041] In this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element. The term "two or more" includes two or more than two.

[0042] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification. Figures 1-12 A fiber optic acoustic sensor 100 according to some embodiments of the present application is described.

[0043] As shown in Figures 1-4 , the fiber optic acoustic sensor 100 according to some embodiments of the present application comprises a support 10 and a mandrel 30.

[0044] The mandrel 30 is mounted on the support 10, and an acoustic sensing fiber (not shown in the figure) can be wound on the outer peripheral wall of the mandrel 30.

[0045] It can be understood that the acoustic sensing fiber can be used to detect acoustic wave signals, and the principle of the acoustic sensing fiber detecting acoustic waves is to use the phase of coherent Rayleigh scattering light to detect signals such as sound or vibration in the audio range, and the type of the acoustic sensing fiber can be bare fiber, tight jacket fiber, loose jacket fiber, FBG fiber, etc., which is not limited here.

[0046] In some embodiments, as shown in Figure 5 and Figure 6 , the outer peripheral wall of the mandrel 30 is provided with a sensitivity enhancing protrusion 31 protruding towards the radial outer side of the mandrel 30.

[0047] It can be understood that the mandrel 30 is not a traditional cylindrical structure, i.e., the cross section of the mandrel 30 is not circular, but is provided with a sensitivity enhancing protrusion 31 protruding towards the radial outer side of the mandrel 30, and the design of the sensitivity enhancing protrusion 31 can effectively enhance the coupling efficiency of the radial strain under the action of the acoustic wave to the axial strain of the fiber, thereby improving the response sensitivity of the acoustic sensing fiber to the acoustic wave signals.

[0048] For example Figure 3 , the axis of the mandrel 30 is denoted by M, the maximum distance of the sensitivity enhancing protrusion 31 to the axis of the mandrel 30 is L1, the minimum radius of the mandrel 30 is L2, and it satisfies: 0.2mm≤L1-L2≤5mm.

[0049] It can be understood that the maximum distance between the sensitivity enhancing protrusion 31 and the axis of the mandrel 30 refers to the distance from the end of the sensitivity enhancing protrusion 31 away from the mandrel 30 to the axis of the mandrel 30 in the radial direction of the mandrel 30 (as shown by L1 in Figure 6 , and the minimum radius of the mandrel 30 refers to the minimum distance from the inner peripheral wall of the mandrel 30 to the axis of the mandrel 30 (as shown by L2 in Figure 6 , and the maximum distance of the sensitivity enhancing protrusion 31 to the axis of the mandrel 30 is greater than the minimum radius of the mandrel 30, i.e., L1 is greater than L2.

[0050] For example, L1-L2=0.2mm, L1-L2=2.5mm, L1-L2=3.6mm or L1-L2=5mm, i.e. the difference between the maximum distance L1 of the sensitivity-enhancing protrusion 31 to the axis of the mandrel 30 and the minimum radius L2 of the mandrel 30 can be 0.2mm, 2.5mm, 3.6mm or 5mm. When the difference between the maximum distance of the sensitivity-enhancing protrusion 31 to the axis of the mandrel 30 and the minimum radius of the mandrel 30 is within the above range, the strain concentration effect of the acoustic fiber can be enhanced, and the sensitivity of the acoustic fiber to the acoustic signal can be improved.

[0051] According to the optical fiber acoustic sensor 100 described in the embodiments of the present application, by arranging the sensitivity-enhancing protrusion 31 on the outer circumferential wall of the mandrel 30 and limiting the difference between the maximum distance L1 of the sensitivity-enhancing protrusion 31 to the axis of the mandrel 30 and the minimum radius L2 of the mandrel 30, the coupling capability between the acoustic wave and the acoustic fiber can be effectively enhanced, and the sensitivity of the optical fiber acoustic sensor 100 to the acoustic signal can be improved.

[0052] In some embodiments, the sensitivity-enhancing protrusion 31 is arranged in plurality, and the plurality of sensitivity-enhancing protrusions 31 are sequentially connected in the circumferential direction of the mandrel 30 to form the mandrel 30.

[0053] In this way, the cross section of the mandrel 30 is formed in a corrugated shape, so that the coupling efficiency between the acoustic wave and the mandrel 30 is enhanced by optimizing the shape of the mandrel 30, and the sensitivity of the acoustic fiber is further improved, making it more suitable for high-precision acoustic detection scenarios.

[0054] In some embodiments, as shown in Figure 5 and Figure 6 The sensitivity-enhancing protrusion 31 is arranged in plurality, and the plurality of sensitivity-enhancing protrusions 31 are arranged around the circumferential direction of the mandrel 30.

[0055] It can be understood that since the acoustic fiber is wound around the mandrel 30, and the plurality of sensitivity-enhancing protrusions 31 are arranged in the circumferential direction of the mandrel 30, the coupling efficiency of the radial strain under the action of the acoustic wave to the axial strain of the optical fiber can be enhanced at different positions in the circumferential direction of the mandrel 30, and the response sensitivity of the acoustic fiber to the acoustic signal at different positions in the circumferential direction of the mandrel 30 can be improved.

[0056] In some embodiments, the plurality of sensitivity-enhancing protrusions 31 are uniformly distributed along the circumferential direction of the mandrel 30, or the plurality of sensitivity-enhancing protrusions 31 are periodically distributed along the circumferential direction of the mandrel 30.

[0057] It can be understood that the uniform distribution of the plurality of sensitivity-enhancing protrusions 31 along the circumference of the mandrel 30 means that the protrusion degree of each sensitivity-enhancing protrusion 31 is the same, and the number of the sensitivity-enhancing protrusions 31 included in a certain central angle range is the same. The periodic distribution means that the plurality of sensitivity-enhancing protrusions 31 can be distributed in at least one of a sine wave, a square wave, a rectangular wave, a modified sine wave, a triangular wave, and a sawtooth wave. In this way, the response of the acoustic measuring optical fiber to the acoustic wave of a specific frequency band can be enhanced.

[0058] In some embodiments, as shown in Figure 5 and Figure 6 , the mandrel 30 is configured as a tubular structure, the sensitivity-enhancing protrusions 31 extend along the axial direction of the mandrel 30, and the plurality of sensitivity-enhancing protrusions 31 are sequentially connected to form the wall of the tubular structure.

[0059] In this way, the wall of the mandrel 30 can be formed in a corrugated shape, so as to enhance the coupling efficiency of the acoustic wave and the mandrel 30 by optimizing the shape of the mandrel 30, and further improve the sensitivity of the acoustic measuring optical fiber, so that it is more suitable for high-precision acoustic detection scenarios.

[0060] In some embodiments, in the thickness direction of the wall, the wall thickness at the connection between the two adjacent sensitivity-enhancing protrusions 31 is smaller than the thickness of the sensitivity-enhancing protrusions 31.

[0061] It can be understood that, in the radial direction of the mandrel 30, the position with the largest distance from the center of the mandrel 30 is the wave crest, the position with the smallest distance from the center of the mandrel 30 is the wave trough, and the connection between the two adjacent sensitivity-enhancing protrusions 31 has the smallest distance from the center of the mandrel 30, that is, the connection between the two adjacent sensitivity-enhancing protrusions 31 is the wave trough, and the thinning area 32 can be arranged in the wave trough area, as shown in Figure 5 and Figure 6 , the thinning area 32 is located at the connection between the two adjacent sensitivity-enhancing protrusions 31, so that the thickness of the thinning area 32 is smaller than the thickness of the remaining areas of the sensitivity-enhancing protrusions 31. In this way, the strain concentration effect of the acoustic measuring optical fiber can be further enhanced, and the sensitivity of the acoustic measuring optical fiber to the acoustic signal can be improved.

[0062] In some embodiments, the number of the sensitivity-enhancing protrusions 31 is positively correlated with the sensitivity of the acoustic measuring optical fiber; and / or the radius of the mandrel 30 is positively correlated with the sensitivity of the acoustic measuring optical fiber; and / or the wall thickness of the mandrel 30 is negatively correlated with the sensitivity of the acoustic measuring optical fiber.

[0063] It can be understood that the sensitivity-enhancing principle of the present application is a geometrically induced compliance principle, which means that the corrugated structure has a characteristic that the corrugated direction has low stiffness and other directions have high stiffness. By using this mechanical anisotropy, the sensitivity of the optical fiber can be enhanced, and the mechanical strength can be ensured.

[0064] The following explanation uses a mandrel 30 as a tubular structure, with multiple sensitizing protrusions 31 extending axially along the mandrel 30. These protrusions 31 are evenly distributed and sequentially connected to form the wall of the tubular structure. The mandrel 30 is described below as a corrugated hollow cylindrical mandrel, with the protrusions 31 arranged in a corrugated pattern.

[0065] The corrugated lines on the inner surface of a corrugated hollow cylindrical mandrel can be represented in polar coordinates as: ,

[0066] in, θ Polar angle, r 0 is the radius of the central circle of the mandrel 30. f ( θ ) is the ripple characteristic function, and f ( θ Let be a periodic function that satisfies: In the formula, m represents the number of sensitizing protrusions 31. The ripple amplitude is defined. A : The above is the general formula for wavy lines. This embodiment uses sinusoidal wavy lines. When the wavy lines are sinusoidal, there is... Expand the thickness of the equation outward. t This forms a hollow corrugated structure. The distance from the peak of the outer surface of the mandrel 30 (the position where the distance from the sensitizing protrusion 31 to the center of the mandrel 30 is the largest) to the center point is defined as the outer radius. R ,have: r = r 0+ A + t The inner radius is defined as the distance from the inner surface trough (the position where the distance from the center of the sensitizing protrusion 31 to the center of the mandrel 30 is the smallest) to the center point. r ,have r = r 0- A The sinusoidal ripple curve described above can also be represented by the following parametric equation in the Cartesian coordinate system, and the two are equivalent.

[0067]

[0068] It should be noted that the parametric description using a sinusoidal wave as an example is only a preferred embodiment. For other periodic wave shapes such as trapezoids, triangles, sawtooth shapes, and rectangles, as long as they satisfy the characteristics of periodic undulations along the circumference and continuity along the axial direction, the outer radius can also be defined. R , inner radius r ripple amplitude A The number of sensitizing protrusions 31 m and wall thickness tThe aforementioned sensitization mechanism of "geometrically induced compliance" applies to a series of periodically corrugated mandrels 30, and is not limited to a specific waveform.

[0069] Finite element simulation results show that the maximum radial strain of the corrugated hollow cylindrical mandrel under unit sound pressure is ε r With outer radius R It exhibits a monotonically increasing relationship with the ripple amplitude. A The relationship is monotonically increasing, which is related to the number of sensitizing protrusions 31. m The relationship between the thickness of the mandrel (30) and the wall thickness (t) increases monotonically, while the relationship between the thickness of the mandrel (30) and the wall thickness (t) decreases monotonically. Specifically, assuming the same manufacturing materials, it can be approximated that: .

[0070] That is, on the outer radius R Increase, ripple amplitude A Increase the number of enlarged and sensitized protrusions 31 m Increase, wall thickness t When the diameter decreases, the radial strain generated by the corrugated mandrel 30 ε r The larger the value, the greater the axial strain generated by the optical fiber, the more obvious the optical phase change, and the higher the sensitivity.

[0071] Radial strain of hollow cylindrical mandrels without sensitizing protrusions 31 in related technologies ε rcy In contrast, under the same sound pressure, the radial strain ratio of the corrugated hollow cylindrical mandrel satisfies: .

[0072] in k >1 and is a constant; in this embodiment, the outer radius is... R It is 33.2mm thick. t The ripple amplitude is 1.2mm. A The number of sensitizing protrusions is 31, with a diameter of 2mm. m The value is 19. Under the parameter configuration of this embodiment, simulation and experimental results show... k The value is approximately 12.

[0073] like Figure 7 As shown, at the same sound frequency, the sensitivity of the corrugated hollow cylindrical mandrel of this application is greater than that of the non-corrugated cylindrical mandrel in the related art.

[0074] like Figure 8 As shown, Figure 8 Figure (a) in the figure shows the time-frequency diagram of the corrugated hollow cylindrical mandrel unmanned aerial vehicle of this application. Figure 8Fig. (b) in the figure shows the time-frequency diagram of the non-ripple cylindrical mandrel unmanned aerial vehicle in the related art, according to the above two figures, the signal-to-noise ratio of the ripple hollow cylindrical mandrel of the present application is higher, and the signal quality is better.

[0075] Therefore, through the above analysis, it is known that the number of the sensitivity-enhancing protrusions 31 is proportional to the sensitivity of the acoustic measurement optical fiber, the radius of the mandrel 30 is proportional to the sensitivity of the acoustic measurement optical fiber, and / or the wall thickness of the mandrel 30 is inversely proportional to the sensitivity of the acoustic measurement optical fiber. Therefore, according to the above relationship, the number of the sensitivity-enhancing protrusions 31, the radius of the mandrel 30, and the wall thickness of the mandrel 30 can be designed to meet the design of improving the sensitivity of the acoustic measurement optical fiber in detecting acoustic signals.

[0076] In some embodiments, the sensitivity-enhancing protrusions 31 include at least one of a corrugated shape and a polygonal shape.

[0077] For example, the sensitivity-enhancing protrusions 31 are configured in a corrugated shape, or the sensitivity-enhancing protrusions 31 are configured in a triangular shape, a quadrangular shape, or other polygonal shapes, or part of the sensitivity-enhancing protrusions 31 are configured in a corrugated shape and the rest of the sensitivity-enhancing protrusions 31 are configured in a triangular shape, etc. Therefore, no matter what shape the sensitivity-enhancing protrusions 31 are, as long as at least part of the sensitivity-enhancing protrusions 31 protrude towards the radial outside of the mandrel 30, the coupling capability between the acoustic wave and the acoustic measurement optical fiber can be effectively enhanced, thereby improving the sensitivity of the optical fiber sound sensor 100 in detecting acoustic signals. At the same time, the temperature measurement optical fiber can also be arranged on the support 10, so that the temperature measurement optical fiber and the acoustic measurement optical fiber can be integrated, thereby integrating the acoustic wave measurement and temperature measurement functions, and further improving the comprehensive performance of the optical fiber sound sensor 100.

[0078] In some embodiments, as shown in Figure 4 The optical fiber sound sensor 100 further includes a mounting bracket 50, the mounting bracket 50 is connected to the support 10 and extends along the radial direction of the mandrel 30, and one axial end of the mandrel 30 is connected to the mounting bracket 50.

[0079] In this way, the one axial end of the mandrel 30 can be mounted on the mounting bracket 50, thereby realizing the connection between the mandrel 30 and the support 10. In particular, the mounting bracket 50 extends along the radial direction of the mandrel 30, so that the arrangement of the mounting bracket 50 does not excessively occupy the space in the axial direction of the mandrel 30, and the one axial end of the mandrel 30 is connected to the mounting bracket 50, which can avoid the interference between the acoustic measurement optical fiber and the mounting bracket 50, thereby making the layout more reasonable.

[0080] In some embodiments, as shown in Figure 4 The optical fiber sound sensor 100 further includes a damping structure 60, the damping structure 60 is mounted on the mounting bracket 50, and the mandrel 30 is mounted on the damping structure 60.

[0081] For example, in the use scenario of applying the optical fiber sound sensor 100 to a belt conveyor, the optical fiber sound sensor 100 needs to be fixed on the shelf of the belt conveyor, and the running of the belt conveyor itself will cause its own vibration, which will interfere with the sound wave. The axial end of the mandrel 30 in the application is suspended on the mounting bracket 50 through the damping structure 60, which can absorb the vibration and reduce the interference of the vibration on the sound wave, and reduce the vibration force suffered by the mandrel 30 and the sound-measuring optical fiber, thereby improving the stability of the working environment of the sound-measuring optical fiber. At the same time, single-end suspension damping of the mandrel 30 can be realized, so as to ensure that the acquisition of the sound wave signal is more stable and reliable.

[0082] In some embodiments, as shown in Figure 4 The optical fiber sound sensor 100 further comprises a connecting piece 70 connected between the damping structure 60 and the mandrel 30.

[0083] Wherein, as shown in Figure 9 The connecting piece 70 is provided with a plurality of first connecting positions 71 and a plurality of second connecting positions 72. The plurality of first connecting positions 71 are distributed along a first direction and are used to be connected with the damping structure 60. The plurality of second connecting positions 72 are distributed along a second direction and are used to be connected with the mandrel 30. The first direction and the second direction intersect and both extend along the radial direction of the mandrel 30.

[0084] In this way, the distribution direction of the plurality of damping structures 60 intersects with the distribution direction of the plurality of second connecting positions 72, so as to reduce the transmission of vibration between the damping structure 60 and the mandrel 30 when external vibration occurs, thereby ensuring that the acquisition of the sound wave signal is more stable and reliable.

[0085] In some embodiments, the distance from the first connecting position 71 to the axis of the mandrel 30 is less than the distance from the second connecting position 72 to the axis of the mandrel 30.

[0086] For example, the second connecting position 72 is connected with the outer peripheral wall of the mandrel 30, and in the axial direction of the mandrel 30, the orthogonal projection of the damping structure 60 falls within the mandrel 30. In this way, the arrangement of the damping structure 60 does not occupy the space on the radial outside of the mandrel 30, thereby facilitating the optimization of space arrangement and making the arrangement of the damping structure 60 and the mandrel 30 more compact.

[0087] In some embodiments, as shown in Figure 1 The bracket 10 comprises a base 11 and an upper cover 12. The base 11 and the upper cover 12 are connected to define a mounting space 20. The mandrel 30 is located in the mounting space 20, and the upper cover 12 is provided with a sound-measuring hole 121 communicating with the mounting space 20.

[0088] In this way, the upper cover 12 can play a certain protective role for the mandrel 30, thereby ensuring the stability of the working environment of the mandrel 30. At the same time, as shown in Figure 1As shown, the upper cover 12 is provided with a sound measuring hole 121 which is in communication with the mounting space 20, so that the sound wave signal can enter the mounting space 20 through the sound measuring hole 121, thereby reducing the obstruction of the shell to the sound wave signal, so as to facilitate the improvement of the sensitivity of the sound measuring optical fiber in detecting the sound wave signal.

[0089] In some embodiments, as shown in Figure 10 As shown, the base 11 is provided with a fiber winding disc 111, a shielding eave 112 and a first threaded groove 113, as shown in Figure 11 As shown, the upper cover 12 is provided with a second threaded groove 124 and a reinforcing rib 125.

[0090] As can be understood, as shown in Figure 4 As shown, the fiber winding disc 111 is located in the mounting space 20, and the fiber winding disc 111 can be used to wind the redundant sound measuring optical fiber, and the fiber winding disc can be configured as a petal-shaped structure, the petal-shaped structure is a cylindrical structure, and the cylindrical structure is provided with a plurality of protrusions, so that the sound measuring optical fiber can enter and exit the fiber winding disc 111 between two adjacent protrusions, thereby reducing the difficulty of the sound measuring optical fiber entering and exiting the fiber winding disc 111.

[0091] As shown in Figure 4 The upper cover 12 can be inserted into the base 11, and the shielding eave 112 is located at the side of the connection between the upper cover 12 and the base 11 away from the mounting space 20, so as to facilitate the use of the shielding eave 112 to organize the entry of sundries or liquid into the mounting space 20.

[0092] As shown in Figure 4 As shown, the first threaded groove 113 and the second threaded groove 124 can be oppositely arranged at the connection between the base 11 and the upper cover 12 to form a threaded groove 40, and the threaded hole is used to fix the external threaded protection tube, and the first threaded groove 113 and the second threaded groove 124 are arranged on the base 11 and the upper cover 12 respectively, so as to reduce the difficulty of setting the threaded hole.

[0093] In some embodiments, as shown in Figure 1 and Figure 2 As shown, the sound measuring hole 121 is provided with a plurality of sound measuring holes 121 which are distributed along the axial direction of the mandrel 30, so that the number of sound measuring holes 121 is increased to reduce the obstruction of the shell to the sound wave signal, thereby facilitating the improvement of the sensitivity of the sound measuring optical fiber in detecting the sound wave signal.

[0094] In some embodiments, the upper cover 12 is provided with a matching groove 122 for winding the connecting rope, and the matching groove 122 is arranged between two adjacent sound measuring holes 121.

[0095] It can be understood that the optical fiber acoustic sensor 100 can be bound to a structure that needs to be fixed through a connecting rope, and the matching groove 122 is arranged in the present application, so that the connecting rope can be clamped in the matching groove 122, thereby avoiding the sliding of the connecting rope, and further improving the binding effect of the connecting rope on the optical fiber acoustic sensor 100.

[0096] At the same time, the area between the two adjacent sound measuring holes 121 is used to arrange the matching groove 122, so as to improve the space utilization rate and avoid the blocking of the connecting rope to the sound measuring hole 121.

[0097] In some embodiments, as shown in Figure 1 The upper cover 12 is provided with a mounting groove 123 for accommodating at least part of the temperature measuring optical fiber. In this way, by arranging the mounting groove 123 on the upper cover 12, the temperature measuring optical fiber can be embedded in the mounting groove 123, thereby reducing the fixing difficulty of the temperature measuring optical fiber and the upper cover 12, and the structure of the mounting groove 123 is relatively simple, which is beneficial to reducing the design cost.

[0098] It can be understood that the temperature measuring optical fiber can be used to detect temperature signals, and in some embodiments, the temperature measuring optical fiber is often realized by relying on a Bragg fiber grating (FBG), a Raman scattering optical fiber or other special optical fiber structure. Temperature change will cause changes in the refractive index and grating period of the optical fiber, thereby causing wavelength drift, based on which temperature monitoring can be realized.

[0099] In the present application, the temperature measuring optical fiber is arranged on the upper cover 12, i.e. the temperature measuring optical fiber is arranged on the bracket 10, and the sound measuring optical fiber is arranged on the mandrel 30, so that the temperature measuring optical fiber and the sound measuring optical fiber can be integrated, thereby enabling the optical fiber acoustic sensor 100 to combine temperature measurement function and sound wave detection function, and further realizing multi-parameter synchronous measurement of sound wave and temperature, thereby simplifying the wiring structure and improving the integration and engineering applicability of the optical fiber acoustic sensor 100.

[0100] In some embodiments, a plurality of optical fiber acoustic sensors 100 can be arranged in an array to improve the detection range of temperature signals and sound signals.

[0101] It can be understood that a plurality of rows and columns of optical fiber acoustic sensors 100 can be arranged to array them, for example, a plurality of rows and columns of optical fiber acoustic sensors 100 can be arranged, or as shown in Figure 12 A plurality of columns of optical fiber acoustic sensors 100 can be arranged, for example, a plurality of optical fiber acoustic sensors 100 can be arranged at intervals along the length direction of the mounting rod 200.

[0102] The sound measuring optical fiber needs to be a tight-fitting optical fiber or an optical fiber jumper with a two-layer sheath, and has a layer of metal / plastic threaded pipe protection outside the sound measuring optical fiber to ensure the structural stability of the sound measuring optical fiber.

[0103] In some embodiments, the wall thickness of the mandrel 30 is in a range from 0.3mm to 3mm.

[0104] For example, the wall thickness of the mandrel 30 can be 0.3mm, 0.5mm, 2mm or 3mm. When the wall thickness of the mandrel 30 is in the above range, the strain concentration effect of the acoustic fiber can be enhanced, and thus the sensitivity of the acoustic fiber to the acoustic signal can be improved.

[0105] In some embodiments, the maximum radius of the mandrel 30 is in a range from 5mm to 60mm.

[0106] For example, the maximum radius of the mandrel 30 can be 5mm, 10mm, 20mm or 60mm. When the maximum radius of the mandrel 30 is in the above range, the strain concentration effect of the acoustic fiber can be enhanced, and thus the sensitivity of the acoustic fiber to the acoustic signal can be improved.

[0107] In some embodiments, the number of the sensitivity enhancing protrusions 31 is in a range from 3 to 31.

[0108] For example, the number of the sensitivity enhancing protrusions 31 can be 18, 19, 20 or 30. When the number of the sensitivity enhancing protrusions 31 is in the above range, the strain concentration effect of the acoustic fiber can be enhanced, and thus the sensitivity of the acoustic fiber to the acoustic signal can be improved.

[0109] In the description of the present application, it should be understood that the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0110] In addition, the terms “first” and “second” are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with “first” and “second” can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of “multiple” is two or more, unless otherwise specifically limited.

[0111] In this application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixed", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection, and can also be communication; can be direct connection, or indirect connection through intermediate medium; can be internal communication of two elements, or interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0112] In this application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0113] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0114] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. An optical fiber acoustic sensor (100), characterized by, The application relates to a sound measuring device. The device comprises: a support (10); a mandrel (30) mounted on the support (10); a sound measuring fiber wound on the outer circumferential wall of the mandrel (30); wherein the outer circumferential wall of the mandrel (30) is provided with sensitivity-enhancing protrusions (31) protruding towards the radial outside of the mandrel (30), the maximum distance of the sensitivity-enhancing protrusions (31) from the axis of the mandrel (30) is L1, the minimum radius of the mandrel (30) is L2, and the following condition is met: 0.2mm<=L1-L2<=5mm; a plurality of the sensitivity-enhancing protrusions (31) are arranged circumferentially around the mandrel (30); the mandrel (30) is configured as a tubular structure, the sensitivity-enhancing protrusions (31) extend along the axial direction of the mandrel (30), and the plurality of the sensitivity-enhancing protrusions (31) are connected in sequence to form the tube wall of the tubular structure; in the thickness direction of the tube wall, the wall thickness at the connection between two adjacent sensitivity-enhancing protrusions (31) is smaller than the thickness of the sensitivity-enhancing protrusions (31); 2. The optical fiber acoustic sensor (100) according to claim 1, characterized in that, the sensitivity-enhancing protrusions (31) comprise at least one of a corrugated shape and a polygonal shape.

3. The optical fiber acoustic sensor (100) of claim 1, wherein, The plurality of the sensitivity-enhancing protrusions (31) are uniformly distributed along the circumferential direction of the mandrel (30), or the plurality of the sensitivity-enhancing protrusions (31) are periodically distributed along the circumferential direction of the mandrel (30).

4. The optical fiber acoustic sensor (100) according to any one of claims 1-3, characterized in that, The number of the sensitivity-enhancing protrusions (31) is positively correlated with the sensitivity of the sound measuring fiber; and / or the radius of the mandrel (30) is positively correlated with the sensitivity of the sound measuring fiber; and / or the wall thickness of the mandrel (30) is negatively correlated with the sensitivity of the sound measuring fiber.

5. The optical fiber acoustic sensor (100) according to claim 4, characterized in that, The support (10) comprises a base (11) and an upper cover (12), the base (11) and the upper cover (12) are connected to define a mounting space (20), the mandrel (30) is located in the mounting space (20), and the upper cover (12) is provided with sound measuring holes (121) in communication with the mounting space (20). A plurality of the sound measuring holes (121) are arranged along the axial direction of the mandrel (30); 6. The optical fiber acoustic sensor (100) according to claim 5, characterized in that, wherein the upper cover (12) is provided with a matching groove (122) for winding a connecting rope, and the matching groove (122) is arranged between two adjacent sound measuring holes (121). The upper cover (12) is provided with a mounting groove (123) for accommodating at least part of a temperature measuring fiber.

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