Sound pressure sensor with multi-cantilever beam structure

Abstract

The invention discloses a sound pressure sensor of a multi-cantilever beam structure, and relates to the field of sonic sensors, and the sound pressure sensor of the multi-cantilever beam structure comprises a sensing diaphragm which is provided with at least two through holes penetrating along the axial direction of the sensing diaphragm; and the cantilever beams are in one-to-one correspondence with the through holes, one parts of the cantilever beams are connected with the side walls of the through holes, and gaps are formed between the other parts of the cantilever beams and the side walls of the through holes. The frequency response range of the acoustic sensor is widened by arranging the cantilever beams with different sizes, and the acoustic pressure sensor made of the all-quartz material has the advantages of high-temperature stability, good mechanical strength, good chemical stability and the like, so that the acoustic pressure sensor can be used in severe environments such as high pressure, oil gas, high electromagnetic interference and the like.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic wave sensors, in particular to an acoustic pressure sensor with a multi-cantilever beam structure. Background Art

[0002] The development of modern industry and people's production and life all rely heavily on reliable power supply. In order to achieve the safe operation of power equipment, by detecting the electrical signals, acoustic signals, optical signals, etc. generated during partial discharge, power equipment failures can be discovered early to reduce economic losses caused by partial discharge and other problems. Microphones, as an acoustic sensor that converts sound pressure signals into electrical signals, are widely used in the detection of acoustic signals generated by partial discharge. The sound signals emitted by partial discharge have the characteristics of weak signals and a wide frequency range, while the existing cantilever optical microphones have a narrow frequency response range and cannot meet the requirements of high sensitivity and wide-band response at the same time. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention is proposed.

[0004] Therefore, the problem to be solved by the present invention is how to improve the sensitivity of the sound pressure sensor and achieve wide-band response.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a sound pressure sensor with a multi-cantilever beam structure, comprising: a sensing diaphragm, which is provided with at least two through holes extending axially through the sensing diaphragm; a cantilever beam, which corresponds one-to-one to the through holes, a part of the cantilever beam is connected to the side wall of the through hole, and a gap exists between the remaining part and the side wall of the through hole.

[0006] As a preferred solution of the sound pressure sensor of the multi-cantilever beam structure of the present invention, the through hole is geometrically similar in shape to the cantilever beam and the projection of the through hole in its thickness direction is larger than the projection of the cantilever beam in its thickness direction.

[0007] As a preferred solution of the sound pressure sensor with a multi-cantilever beam structure of the present invention, the through holes and the cantilever beams corresponding thereto are evenly arranged in a ring array on the sensing diaphragm.

[0008] As a preferred solution of the sound pressure sensor with multiple cantilever beam structure of the present invention, the sizes of the cantilever beams are different from each other.

[0009] As a preferred solution of the sound pressure sensor with multiple cantilever beam structure of the present invention, the materials of the cantilever beams are different from each other.

[0010] As a preferred solution of the sound pressure sensor with a multi-cantilever beam structure of the present invention, the sensing diaphragm and the cantilever beam are both made of quartz.

[0011] As a preferred solution of the sound pressure sensor with a multi-cantilever beam structure described in the present invention, a first supporting diaphragm and a second supporting diaphragm are respectively arranged on both axial sides of the sensing diaphragm, and a first through hole and a second through hole are respectively arranged at positions of the first supporting diaphragm and the second supporting diaphragm corresponding to the cantilever beam.

[0012] As a preferred solution of the sound pressure sensor with a multi-cantilever beam structure described in the present invention, a sleeve is fixedly arranged on the side of the first supporting diaphragm or the second supporting diaphragm away from the sensing diaphragm, a cavity is arranged inside the end of the sleeve close to the first supporting diaphragm or the second supporting diaphragm, and at least two optical fiber holes are arranged inside the sleeve, and the optical fiber holes correspond one-to-one to the free ends of the cantilever beams.

[0013] As a preferred solution of the sound pressure sensor with a multi-cantilever beam structure of the present invention, an optical fiber is arranged inside the optical fiber hole, the end of the optical fiber corresponds one-to-one with the free end of the cantilever beam, and the optical fiber is a single-mode optical fiber.

[0014] As a preferred solution of the sound pressure sensor with a multi-cantilever beam structure described in the present invention, the sensing diaphragm, the cantilever beam, the sleeve and the optical fiber are all made of quartz.

[0015] The beneficial effects of the present invention are as follows: the present invention broadens the frequency response range of the acoustic sensor by setting cantilever beams of different sizes, and the sound pressure sensor made of all quartz material has the advantages of high temperature stability, good mechanical strength and chemical stability, thereby ensuring that the sound pressure sensor of the present invention can be used in harsh environments such as high pressure, oil and gas, and high electromagnetic interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 Schematic diagram of the sensing diaphragm and cantilever beam structure.

[0018] Figure 2 This is an axial front view of the sensing diaphragm and cantilever beam structure.

[0019] Figure 3It is a schematic diagram of the structures of the sensing diaphragm, the first supporting diaphragm and the second supporting diaphragm.

[0020] Figure 4 A perspective view of the sound pressure sensor structure with multiple cantilever beams.

[0021] Figure 5 This is an axial front structural perspective view of the sound pressure sensor with a multi-cantilever beam structure.

[0022] Figure 6 Schematic diagram of the simulated force and deformation of the sound pressure sensor with a multi-cantilever beam structure.

[0023] Figure 7 Schematic diagram of the multi-eigenfrequency frequency response range simulated for a sound pressure sensor with a multi-cantilever beam structure. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0027] Reference Figure 1 to Figure 7 , is an embodiment of the present invention, which provides a sound pressure sensor with a multi-cantilever beam structure. The sound pressure sensor with a multi-cantilever beam structure includes a sensing diaphragm 100 and a cantilever beam 200.

[0028] Specifically, refer to Figure 1 and Figure 2 The sensing diaphragm 100 is provided with at least two through holes 101 penetrating along its axial direction. In this embodiment, three through holes 101 are provided and arranged in a ring shape along the circumference of the sensing diaphragm 100, and each through hole 101 is spaced 120 degrees apart from each other. In this embodiment, the projection of the through hole 101 in its thickness direction is a rectangle.

[0029] The number of cantilever beams 200 corresponds to the through hole 101 and all of them are arranged in the through hole 101. The geometric shape of the cantilever beam 200 is similar to that of the through hole. The shape of the cantilever beam 200 includes but is not limited to a rectangle, and can be a trapezoid, etc. In this embodiment, the shape of the cantilever beam 200 is selected to be a rectangle, which is similar to the shape of the through hole. One end of the cantilever beam 200 is fixed to the side wall of the through hole 101, and there is a certain gap between the other three ends and the side wall of the through hole 101, that is, the through hole 101 is slightly larger than the cantilever beam 200, so that when the free end of the cantilever beam 200 is subjected to sound pressure, the free end of the cantilever beam 200 can swing along the axial direction of the sensing diaphragm 100.

[0030] Preferably, the three cantilever beams 200 have different sizes and can be made of the same material. Due to the different sizes, the eigenfrequencies of the three cantilever beams 200 are different even though they are made of the same material. When the frequency of the acoustic signal matches the eigenfrequencies, a resonance peak is formed. The resonance frequency is the same as the eigenfrequencies, and the sensitivity of the sensor is the highest. Therefore, the three different eigenfrequencies have three resonance peaks, and compared with the ordinary circular diaphragm and cantilever beam structure with only one resonance peak, the frequency range of the response is broadened.

[0031] In order to better illustrate the relationship between the cantilever beam 200 and the sound pressure and its own characteristics, a formula is introduced to express it. As a structure sensitive to sound waves, the cantilever beam 200 usually only acts at the first-order resonant frequency. Therefore, the designed structure can be simplified into a one-dimensional particle resonance model. When the sound wave acts on the cantilever beam 200 on the sensing diaphragm 100, the vibration of the free end of the cantilever beam 200 can be expressed by the motion equation shown in the formula and the first-order resonant frequency ω0 can be expressed as:

[0032]

[0033] Wherein, m represents the effective mass of the cantilever beam 200, x represents the displacement change of the free end of the cantilever beam 200, D represents the damping coefficient, k represents the stiffness coefficient of the cantilever beam 200, and F ex (t) represents the pressure on the cantilever beam. l, w, t are respectively the length, width and thickness of the designed cantilever beam 200. E is the Young's modulus of the cantilever beam 200. is the density of the cantilever beam 200 material.

[0034] The sensitivity of the cantilever beam 200 is related to the displacement of the free end of the cantilever beam 200. The greater the displacement, the greater the change in the cavity length and the greater the change in the intensity of the interference light.

[0035] The displacement variation of the free end of the cantilever beam 200 is solved, and the frequency response of the free end of the cantilever beam 200 can be expressed as:

[0036]

[0037] Among them, ω is the angular frequency, ω0 is the frequency of the acoustic signal applied to the surface of the cantilever beam 200. This formula shows that the frequency response is related to the frequency of the acoustic signal. When the applied signal frequency matches the frequency of the cantilever beam 200 itself, the frequency response can reach the maximum.

[0038] Better, refer to Figure 3 , a first supporting diaphragm 300 and a second supporting diaphragm 400 are also provided on both sides of the sensing diaphragm 100, which form a "sandwich" structure with the sensing diaphragm 100. The upper and lower layers of diaphragms are used to increase the mechanical stability of the sensor. The diameter and thickness of the first supporting diaphragm 300 and the second supporting diaphragm 400 are the same, and the thickness is much greater than the thickness of the sensing diaphragm 100. The thinner the sensing diaphragm 100, the greater the sensitivity of the sensor. The positions of the first through holes 301 and the second through holes 401 on the first supporting diaphragm 300 and the second supporting diaphragm 400 correspond to the positions of the cantilever beam 200 and are evenly arranged. When the cantilever beam is subjected to sound pressure, the even arrangement can ensure that the cantilever beam 200 is subjected to the same sound pressure.

[0039] Reference Figure 4 A sleeve 500 is fixed on one side of the first supporting diaphragm 300 or the second supporting diaphragm 400. A cavity 501 is provided at one end of the sleeve 500 close to the sensing diaphragm 100 to ensure that the cantilever beam 200 will not be obstructed when the vibration amplitude is large. Three optical fiber holes 502 are also provided in the sleeve 500, forming three Fabry-Perot cavities with the three cantilever beams 200. Light 600 is installed in the optical fiber hole 502, and the light 600 is a single-mode optical fiber.

[0040] Preferably, the diameter of the sensing diaphragm 100 is 5 mm and the thickness is 50 μm. The length of the sleeve 500 is 10 mm, the outer radius is 5 mm, the inner radius is 4 mm, and the wall thickness is 1 mm. The outer diameter of the coating layer of the optical fiber 600 is 242±5 μm, the outer diameter of the cladding is 125±0.7 μm, and the core is 9±0.5 μm.

[0041] The present invention is based on the Fabry-Perot principle: the cantilever beam 200 is used as a transducer, and the acoustic wave signal acts on the cantilever beam 200 to cause mechanical vibration. One end of the cantilever beam 200 is fixed, so the vibration is up and down. When it vibrates and deforms, the distance between the cantilever beam 200 and the optical fiber 600 changes, and the cavity length of the Fabry-Perot cavity changes, thereby causing the spectrum to change.

[0042] Therefore, the end face of the optical fiber 600 is aligned with the free end of the cantilever beam 200, so as to ensure that the change in the cavity length of the Fabry-Perot cavity is maximized. Figure 5 shown.

[0043] In order to better verify the technical effect of the present invention, a simulation test is now carried out on the sensor of the present invention. Figure 6 In order to use COMSOL multi-physics simulation software, the boundary conditions and load conditions of the multiple cantilever beams 200 are set through the acoustic-solid multi-physics coupling conditions. The sound pressure conditions are set to be the same, and the uniform pressures on the three cantilever beams 200 are exactly the same.

[0044] Figure 7 The present invention uses COMSOL multi-physics field simulation software to simulate the frequency response range of the multi-cantilever beam structure all-quartz optical fiber sound pressure sensor. The input sound signal frequency is set by the sound-solid multi-physics field coupling condition. The operating frequency of the sound pressure sensor is one-third or three times the resonant frequency. The maximum sensitivity point is located at the resonance peak. Figure 7 The three resonance peaks are separated from each other and have different resonance frequencies, which increases the sensitivity and operating frequency range of the sensor.

[0045] In summary, the optical fiber 600 is a single-mode standard transmission optical fiber, which is used to transmit the incident light and the reflected light passing through the Fabry-Perot interferometer. The end face of the optical fiber 600 serves as the first reflection surface of the Fabry-Perot interferometer, and the lower surface of the cantilever beam 200 serves as the second reflection surface of the Fabry-Perot interferometer.

[0046] The entire sensor works based on the principle of Fabry-Perot interferometer. When the sound pressure acts on the cantilever beam, the cantilever beam is deformed by force, causing the distance between the two reflecting surfaces to change, and the corresponding Fabry-Perot cavity length will also change. Three cantilever beams of different sizes are combined on the same diaphragm, resulting in the frequency response of the sensor having three resonance peaks, which improves the sensitivity of the sensor and broadens the frequency response range of the sensor. The all-quartz material broadens the application range of the sensor.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A sound pressure sensor with a multi-cantilever beam structure, characterized in that: include, A sensing diaphragm (100) having at least two through holes (101) extending axially through the sensing diaphragm (100); A cantilever beam (200) corresponds one-to-one to the through hole (101); a portion of the cantilever beam (200) is connected to the side wall of the through hole (101), and a gap exists between the remaining portion and the side wall of the through hole (101).

2. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 1, characterized in that: The through hole (101) and the cantilever beam (200) are geometrically similar in shape, and the projection of the through hole (101) in the thickness direction is larger than the projection of the cantilever beam (200) in the thickness direction.

3. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 1, characterized in that: The through holes (101) and the corresponding cantilever beams (200) are evenly arranged in a ring array on the sensing diaphragm (100).

4. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 1, characterized in that: The cantilever beams (200) have different sizes from each other.

5. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 1, characterized in that: The cantilever beams (200) are made of different materials.

6. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 1, characterized in that: The sensing diaphragm (100) and the cantilever beam (200) are both made of quartz.

7. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 1, characterized in that: A first supporting diaphragm (300) and a second supporting diaphragm (400) are respectively provided on both axial sides of the sensing diaphragm (100), and a first through hole (301) and a second through hole (401) are respectively provided at positions of the first supporting diaphragm (300) and the second supporting diaphragm (400) corresponding to the cantilever beam (200).

8. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 7, characterized in that: A sleeve (500) is also fixedly arranged on the side of the first supporting diaphragm (300) or the second supporting diaphragm (400) away from the sensing diaphragm (100), and a cavity (501) is arranged inside the end of the sleeve (500) close to the first supporting diaphragm (300) or the second supporting diaphragm (400), and at least two optical fiber holes (502) are also arranged inside the sleeve (500), and the optical fiber holes (502) correspond one-to-one to the free ends of the cantilever beam (200).

9. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 8, characterized in that: An optical fiber (600) is arranged inside the optical fiber hole (502), the end of the optical fiber (600) corresponds one-to-one to the free end of the cantilever beam (200), and the optical fiber (600) is a single-mode optical fiber.

10. The sound pressure sensor with a multi-cantilever beam structure as claimed in claim 9, characterized in that: The sensing diaphragm (100), the cantilever beam (200), the sleeve (500) and the optical fiber (600) are all made of quartz.

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