Multi-dimensional accelerometer

Abstract

The invention provides a multi-dimensional accelerometer, and belongs to the field of multi-dimensional accelerometers, the multi-dimensional accelerometer comprises a main body, a diaphragm, an optical fiber ferrule and a mass fluid, the main body is internally provided with a cavity, the main body is also internally provided with two or three channels, the channels penetrate through the cavity and are mutually crossed in the cavity, and two ends of the channels penetrate through two opposite side surfaces of the main body; each diaphragm is arranged between the end part of the channel and the cavity, and the diaphragms are extruded to elastically deform; the optical fiber insertion core is inserted into one end part of the channel; the mass fluid is filled in the cavity and in the portion of the channel between the two diaphragms, and the mass fluid freely flows relative to the body and squeezes the diaphragms. According to the invention, when the mass fluid moves along with the accelerometer, extrusion force is generated to the diaphragms in the plurality of channels, so that the diaphragms are deformed, the distance between the optical fiber ferrule and the diaphragms is changed to realize acceleration detection, and the diaphragm deformation is very sensitive to the flow change of the mass fluid, so that the detection sensitivity is relatively high; and the transverse interference resistance is high.

Description

Technical Field

[0001] The present invention relates to the technical field of accelerometers, and particularly to a multi-dimensional accelerometer. Background Art

[0002] An optical fiber accelerometer is an acceleration sensor based on the optical principle, which uses optical fiber as the sensing and transmission element to measure the acceleration of an object. The diaphragm type optical fiber accelerometer can meet the requirements of both high sensitivity and miniaturization. However, the existing diaphragm type optical fiber accelerometers often use solid substances as mass elements. For example, the diaphragm type optical fiber accelerometer disclosed in Chinese Patent CN205670157U is difficult to be compatible with high-density inertial mass blocks and sensitive diaphragms with high deformation sensitivity under miniaturized dimensions in order to maintain the structural stability.

[0003] Currently, when extending an optical fiber accelerometer from one dimension to multiple dimensions, a split structure is usually adopted, so it is difficult to achieve the purpose of integrated multi-dimensional synchronous acceleration detection. Summary of the Invention

[0004] In view of this, the present invention provides a multi-dimensional accelerometer to solve the problem that it is currently difficult to achieve integrated multi-dimensional synchronous acceleration detection.

[0005] The technical solution of the present invention is realized as follows: The present invention provides a multi-dimensional accelerometer, which includes a main body, a diaphragm, an optical fiber ferrule, and a mass fluid; a cavity is provided inside the main body, and two or three channels are also provided inside the main body. Each channel passes through the cavity and intersects with each other inside the cavity. Both ends of the channel penetrate through two opposite side surfaces of the main body; two diaphragms are grouped together and sleeved in the same channel at intervals and are respectively close to both ends of the channel. Each diaphragm is arranged between the end of the channel and the cavity, and the diaphragm undergoes elastic deformation under extrusion; the optical fiber ferrule is inserted into one end of the channel, and the optical fiber ferrule emits an optical signal to the diaphragm; the mass fluid is filled inside the cavity and in the part of the channel located between the two diaphragms, and the mass fluid freely flows relative to the main body and extrudes the diaphragm.

[0006] Based on the above technical solution, preferably, it further includes a connecting pipe. One end of the connecting pipe is inserted into the end of the channel and the other end extends out of the main body; a diaphragm is covered on the end surface of the inserted end of the connecting pipe, and an optical fiber ferrule is inserted into the outer end of one of each group of connecting pipes.

[0007] Based on the above technical solution, preferably, the part between the diaphragm that aligns with the optical fiber ferrule in each channel and the cavity is the response section, and the sensitivity and resonance frequency of the multi-dimensional accelerometer are adjusted by adjusting the axial length of the response section or the radius of the diaphragm.

[0008] More preferably, the axial length of the response section is in a direct proportional relationship with the sensitivity of the multi-dimensional accelerometer.

[0009] More preferably, the radius of the diaphragm is in direct proportion to the sensitivity of the multi-dimensional accelerometer, and the radius of the diaphragm is in inverse proportion to the resonance frequency of the multi-dimensional accelerometer.

[0010] More preferably, the axial cross-sectional shape of the response section is trapezoidal, and the end of the response section facing the cavity is the short side of the trapezoid.

[0011] Based on the above technical solutions, preferably, the diaphragm includes a polymer layer, a chromium plating layer and a silver plating layer. The polymer layer is elastically deformed under extrusion. The chromium plating layer is sandwiched between the polymer layer and the silver plating layer, and the silver plating layer faces the optical fiber ferrule.

[0012] More preferably, the sensitivity and resonance frequency of the multi-dimensional accelerometer are adjusted by adjusting the thickness of the polymer layer or the thickness of the silver plating layer.

[0013] More preferably, the thickness of the polymer layer is in inverse proportion to the sensitivity of the multi-dimensional accelerometer, and the thickness of the polymer layer is in direct proportion to the resonance frequency of the multi-dimensional accelerometer.

[0014] More preferably, the thickness of the silver plating layer is in inverse proportion to the sensitivity of the multi-dimensional accelerometer, and the thickness of the silver plating layer is in direct proportion to the resonance frequency of the multi-dimensional accelerometer.

[0015] A multi-dimensional accelerometer of the present invention has the following beneficial effects compared with the prior art:

[0016] (1) The present invention uses a mass fluid as a mass element. When the mass fluid moves with the accelerometer, it generates an extrusion force on the diaphragms in multiple channels, causing the diaphragms to deform. Furthermore, the distance between the optical fiber ferrule and the diaphragms changes to achieve the detection of acceleration. And the deformation of the diaphragms is very sensitive to the flow change of the mass fluid. Therefore, the detection sensitivity is high and the anti-lateral interference ability is strong.

[0017] (2) By adjusting the axial length of the response section or the radius of the diaphragm, or by adjusting the thickness of the polymer layer or the thickness of the silver plating layer, the present invention can adjust the sensitivity and resonance frequency of the multi-dimensional accelerometer, enabling the accelerometer to be applicable to various detection scenarios such as high frequency and low frequency. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 Isometric view of the two-dimensional accelerometer of the present invention;

[0020] Figure 2 Isometric view of the three-dimensional accelerometer of the present invention;

[0021] Figure 3 Side sectional view of the two-dimensional accelerometer of the present invention;

[0022] Figure 4 Cross-sectional view of the diaphragm of the present invention;

[0023] Figure 5 Time-domain diagram of the demodulated signal of the accelerometer of the present invention under a 100 Hz vibration signal;

[0024] Figure 6 Frequency-domain diagram of the demodulated signal of the accelerometer of the present invention under a 100 Hz vibration signal;

[0025] Figure 7 Relationship diagram between phase shift and acceleration of the accelerometer of the present invention under a 100 Hz vibration signal;

[0026] Figure 8 Sensitivity curve diagram of the accelerometer of the present invention at various frequencies;

[0027] Figure 9 Anti-lateral interference test curve diagram of the accelerometer of the present invention between 100 Hz and 200 Hz;

[0028] Figure 10 Diaphragm response curve diagram of the present invention under different response segment lengths;

[0029] Figure 11 Diaphragm response curve diagram of the present invention under different diaphragm radii;

[0030] Figure 12 Diaphragm response curve diagram of the present invention under different polymer layer thicknesses;

[0031] Figure 13 Diaphragm response curve diagram of the present invention under different silver plating layer thicknesses.

[0032] In the figure: 1. Main body; 101. Cavity; 102. Channel; 103. Response segment; 2. Diaphragm; 21. Polymer layer; 22. Chrome plating layer; 23. Silver plating layer; 3. Fiber optic ferrule; 4. Mass fluid; 5. Adapter. Detailed implementation manner

[0033] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] As Figure 1 shown, in combination with Figure 2 , a multi-dimensional accelerometer of the present invention includes a main body 1, a diaphragm 2, an optical fiber ferrule 3, and a mass fluid 4.

[0035] Among them, a cavity 101 is formed inside the main body 1, and two or three channels 102 are also formed in the main body 1. Each channel 102 passes through the cavity 101 and intersects with each other inside the cavity 101. Both ends of the channel 102 penetrate through two opposite side surfaces of the main body 1. The main body 1 is made by 3D printing technology and can be made into a special-shaped structure according to requirements. The main body 1 can be made of metal materials, ceramic materials, or polymer materials with better structural strength. A liquid injection hole for connecting the cavity 101 with the outside can be reserved on the main body 1, and the mass fluid 4 is injected into the cavity 101 through the liquid injection hole.

[0036] Two diaphragms 2 are grouped together and sleeved in the same channel 102 at intervals and are respectively close to both ends of the channel 102. Each diaphragm 2 is arranged between the end of the channel 102 and the cavity 101, and the diaphragm 2 undergoes elastic deformation under extrusion.

[0037] The optical fiber ferrule 3 is inserted into one end of the channel 102, and the optical fiber ferrule 3 emits an optical signal to the diaphragm 2. The tail end of the optical fiber ferrule 3 can be connected to an optical signal transmitting device and a detection device.

[0038] The mass fluid 4 is filled in the cavity 101 and the part of the channel 102 located between the two diaphragms 2. The mass fluid 4 freely flows relative to the main body 1 and extrudes the diaphragm 2.

[0039] When the above technical solution is adopted, during detection, the accelerometer is fixedly installed on the detection piece, and the accelerometer moves synchronously with the piece to be detected, which will cause the mass fluid 4 to flow reciprocally and generate an acceleration. The mass fluid 4 will exert an extrusion force on the diaphragm 2, causing the diaphragm 2 to deform. At this time, the optical signal generating device emits an optical signal towards the surface of the diaphragm 2 through the optical fiber ferrule 3. The optical signal is emitted from the surface of the diaphragm 2 and transmitted back to the detection device through the optical fiber, and the change in the distance between the optical fiber ferrule 3 and the diaphragm 2 is detected. The acceleration can be detected based on the change in the distance. Although the mass fluid 4 can adopt a liquid fluid, the density of the liquid fluid is small, resulting in a small total mass of the mass fluid 4 in the cavity 101. When the acceleration is the same, the extrusion force exerted by the mass fluid 4 on the diaphragm 2 is small. Therefore, the mass fluid 4 is preferably made of a liquid metal material, specifically, a gallium-indium-tin alloy can be used.

[0040] The prepared fiber optic accelerometer was tested. The demodulation system was a fiber optic phase demodulation system. The acceleration was provided by a power amplifier and a vibration table, and a commercial charge accelerometer was used to calibrate the acceleration.

[0041] The time domain and frequency domain diagrams of the demodulated signal are as Figure 5 and Figure 6 shown. The time domain diagram shows that the phase magnitude of the vibration signal is approximately 2.7 rad, and a distinct peak appears at 80 Hz in the frequency domain diagram, indicating that this accelerometer can achieve the measurement of vibration signals.

[0042] The linearity results of the accelerometer are as Figure 7 shown. By comparing with the test results of the electrical accelerometer, the linearity of the accelerometer reaches above 0.999, and the measured phase magnitude is approximately proportional to the acceleration magnitude, indicating that the accelerometer has good accuracy.

[0043] By changing the frequency of the vibration signal, the sensitivity of the accelerometer at each frequency was detected. The results are as Figure 8 shown. It can be seen that the resonant frequency of the accelerometer is approximately 300 Hz, and the sensitivity tends to be flat below 120 Hz and can be used for measurement.

[0044] In Figure 3 a preferred embodiment shown, when specifically implementing by arranging the diaphragm 2 in the main body 1, a connecting pipe 5 is further included.

[0045] Among them, the connecting pipe 5 is a glass pipe. One end of the connecting pipe 5 is inserted into the end of the channel 102 and the other end extends outside the main body 1. A diaphragm 2 is covered on the end face of the inserted end of the connecting pipe 5, and the outer end of one of each group of connecting pipes 5 is inserted with an optical fiber ferrule 3. When assembling the accelerometer, first bond the diaphragm 2 to one end of the glass connecting pipe 5 with UV glue, insert an optical fiber into the other end and cure it with UV glue, so that the connecting pipe 5 and the optical fiber ferrule 4 form a sensitive unit with the ability to sense pressure. Then insert the connecting pipes 5 on both sides of the main body 1 of the two-dimensional or three-dimensional accelerometer respectively, insert the diaphragm 2 into the end of the channel 102, and glue and cure the connecting pipe 5 to the inner wall of the channel 102 with UV glue. Finally, fill the cavity 101 with the mass fluid 4 of gallium-indium-tin alloy material through the reserved liquid injection hole, and then seal the small hole so that the liquid metal is completely enclosed in the cavity 101.

[0046] In Figure 3 In a preferred embodiment shown, the part between the diaphragm 2 aligned with the optical fiber ferrule 3 in each channel 102 and the cavity 101 is the response section 103. The sensitivity and resonance frequency of the multi-dimensional accelerometer are adjusted by adjusting the axial length of the response section 103 or the radius of the diaphragm 2, so that the accelerometer can be applied to various detection scenarios such as high frequency and low frequency.

[0047] In Figure 10 In a preferred embodiment shown, the axial length of the response section 103 is in a direct proportional relationship with the sensitivity of the multi-dimensional accelerometer. For example, in this embodiment, when the thickness of the polymer layer 21 is set to 250 nm, the thickness of the silver-plated layer 23 is set to 200 nm, and the radius of the diaphragm is 1.25 mm, as Figure 10 shown, it can be seen that when the axial length of the response section 103 changes, the peak value of the resonance frequency of the accelerometer is within the range of 300 - 350 Hz, and the larger the axial length of the response section 103, the larger the peak value of the resonance frequency of the accelerometer. Therefore, the sensitivity of the accelerometer is better.

[0048] In Figure 11 In a preferred embodiment shown, the radius of the diaphragm 2 is in a direct proportional relationship with the sensitivity of the multi-dimensional accelerometer, and the radius of the diaphragm 2 is in an inverse proportional relationship with the resonance frequency of the multi-dimensional accelerometer. For example, in this embodiment, when the thickness of the polymer layer 21 is set to 250 nm, the thickness of the silver-plated layer 23 is set to 200 nm, and the axial length of the response section 103 changes to 7 mm, as Figure 11 shown, it can be seen that when the radius of the diaphragm 2 changes, the resonance frequency range of the accelerometer changes with the increase of the radius of the diaphragm 2. For example, the resonance frequency range when the radius of the diaphragm 2 is 1.15 nm is 400 - 450 Hz, and the resonance frequency range when the radius of the diaphragm 2 is 1.55 nm is 200 - 250 Hz; the larger the radius of the diaphragm 2, the larger the peak value of the resonance frequency of the accelerometer. Therefore, the sensitivity of the accelerometer is better.

[0049] In Figure 3 In a preferred embodiment shown, the axial cross-sectional shape of the response section 103 is trapezoidal, and the end of the response section 103 facing the cavity 101 is the short side of the trapezoid. Through the above structural design, the extrusion force exerted by the mass fluid 4 on the diaphragm 2 can be made more concentrated, so that the response sensitivity of the diaphragm 2 to pressure deformation is higher; through Figure 9 it can be found that its ability to resist lateral interference is also stronger.

[0050] In Figure 4 In a preferred embodiment shown, the diaphragm 2 includes a polymer layer 21, a chromium plating layer 22 and a silver plating layer 23.

[0051] Among them, the polymer layer 21 is elastically deformed under extrusion. The polymer layer 21 is made of PMMA material.

[0052] The chromium plating layer 22 is sandwiched between the polymer layer 21 and the silver plating layer 23. The function of the chromium plating layer 22 is to make the silver plating layer 23 and the polymer layer 21 be connected tightly and stably.

[0053] The silver plating layer 23 faces the optical fiber ferrule 3. The silver plating layer 23 can not only improve the structural strength of the diaphragm 2, but also its function is to reflect the optical signal emitted by the optical fiber ferrule 3.

[0054] The preparation process of the diaphragm 2 is as follows: (1) Clean the surface of the silicon substrate, and ultrasonically clean it in deionized water, acetone and ethanol in sequence; (2) Blow dry the cleaned silicon substrate with nitrogen, and place it in an ultraviolet ozone cleaning machine for treatment; (3) Use a magnetron sputtering coating machine to deposit a sacrificial layer film on the silicon substrate; (4) Spin-coat a polymer film (i.e., the polymer layer 21) on the sacrificial layer film, and anneal it at 120 °C on a heating table for 20 min; (5) Use a thermal evaporation coating machine to sequentially evaporate a chromium film and a silver film on the polymer film (i.e., form the chromium plating layer 22 and the silver plating layer 23 in sequence); (6) Dip an appropriate amount of photoresist on the end face of the glass connecting pipe 5, stand it vertically on the prepared diaphragm 2 and perform ultraviolet curing to make the end face of the connecting pipe 5 adhere to the diaphragm 2; (7) Place the diaphragm 2 in a dilute nitric acid solution, wait for the sacrificial layer to dissolve, and the silicon substrate is separated from the diaphragm 2 to obtain a structure in which the diaphragm 2 is adhered to the end face of the connecting pipe 5, and a sensitive unit with the ability to sense pressure is formed.

[0055] In Figure 3 In a preferred embodiment shown, the sensitivity and resonance frequency of the multi-dimensional accelerometer are adjusted by adjusting the thickness of the polymer layer 21 or the thickness of the silver plating layer 23, so that the accelerometer can be applied to various detection scenarios such as high frequency and low frequency.

[0056] In Figure 12In a preferred embodiment shown, the thickness of the polymer layer 21 is inversely proportional to the sensitivity of the multi-dimensional accelerometer, and the thickness of the polymer layer 21 is directly proportional to the resonance frequency of the multi-dimensional accelerometer. For example, in this embodiment, the radius of the diaphragm 2 is set to 1.35 nm, the thickness of the silver-plated layer 23 is 200 nm, and when the axial length change of the response section 103 is 7 mm, as Figure 12 shown, it can be seen that when the thickness of the polymer layer 21 changes, the resonance frequency range of the accelerometer changes with the increase of the thickness of the polymer layer 21. For example, when the thickness of the polymer layer 21 is 150 nm, the resonance frequency range is about 250 Hz, while when the thickness of the polymer layer 21 is 350 nm, the resonance frequency range is 350 - 400 Hz; the smaller the thickness of the polymer layer 21, the larger the peak value of the resonance frequency of the accelerometer, and thus the better the sensitivity of the accelerometer.

[0057] In Figure 13 a preferred embodiment shown, the thickness of the silver-plated layer 23 is inversely proportional to the sensitivity of the multi-dimensional accelerometer, the thickness of the silver-plated layer 23 is directly proportional to the resonance frequency of the multi-dimensional accelerometer, and the thickness of the silver-plated layer 23 is inversely proportional to the resonance frequency range of the multi-dimensional accelerometer. For example, in this embodiment, the radius of the diaphragm 2 is set to 1.25 mm, the thickness of the polymer layer 21 is 250 nm, and when the axial length change of the response section 103 is 7 mm, as Figure 13 shown, it can be seen that when the thickness of the silver-plated layer 23 changes, the resonance frequency range of the accelerometer changes with the increase of the thickness of the silver-plated layer 23. For example, when the thickness of the silver-plated layer 23 is 100 nm, the resonance frequency range is 200 - 250 Hz, while when the thickness of the silver-plated layer 23 is 300 nm, the resonance frequency range is about 400 Hz; the smaller the thickness of the silver-plated layer 23, the larger the peak value of the resonance frequency of the accelerometer, and thus the better the sensitivity of the accelerometer, but at the same time, it can be found that the working frequency range of the accelerometer is smaller when the thickness of the silver-plated layer 23 is smaller.

[0058] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-dimensional accelerometer, characterized in that: It includes a main body (1), a diaphragm (2), an optical fiber ferrule (3) and a mass fluid (4); A cavity (101) is formed inside the main body (1), and two or three channels (102) are further formed in the main body (1). Each of the channels (102) passes through the cavity (101) and intersects with each other inside the cavity (101). Both ends of the channel (102) penetrate through two opposite side surfaces of the main body (1); The diaphragms (2) are arranged in groups of two and sleeved in the same channel (102) at intervals and are respectively close to both ends of the channel (102). Each diaphragm (2) is arranged between the end of the channel (102) and the cavity (101), and the diaphragm (2) undergoes elastic deformation under extrusion; The optical fiber ferrule (3) is inserted into one end of the channel (102), and the optical fiber ferrule (3) emits an optical signal to the diaphragm (2); The mass fluid (4) is filled in the cavity (101) and the part of the channel (102) located between the two diaphragms (2). The mass fluid (4) freely flows relative to the main body (1) and extrudes the diaphragm (2).

2. The multi-dimensional accelerometer according to claim 1, characterized in that: It further includes a connecting pipe (5), One end of the connecting pipe (5) is inserted into the end of the channel (102) and the other end extends out of the main body (1); a diaphragm (2) is covered on the end face of the inserted end of the connecting pipe (5), and an optical fiber ferrule (3) is inserted into the outer end of one of each group of connecting pipes (5).

3. A multi-dimensional accelerometer according to claim 1, characterized in that: The part between the diaphragm (2) aligning with the optical fiber ferrule (3) in each channel (102) and the cavity (101) is a response section (103). The sensitivity and resonance frequency of the multi-dimensional accelerometer are adjusted by adjusting the axial length of the response section (103) or the radius of the diaphragm (2).

4. A multi-dimensional accelerometer according to claim 3, characterized in that: The axial length of the response section (103) is in a direct proportional relationship with the sensitivity of the multi-dimensional accelerometer.

5. The multi-dimensional accelerometer according to claim 3, characterized in that: The radius of the diaphragm (2) is in a direct proportional relationship with the sensitivity of the multi-dimensional accelerometer, and the radius of the diaphragm (2) is in an inverse proportional relationship with the resonance frequency of the multi-dimensional accelerometer.

6. A multi-dimensional accelerometer according to claim 5, characterized in that: The axial cross-sectional shape of the response section (103) is trapezoidal, and the end of the response section (103) facing the cavity (101) is the short side of the trapezoid.

7. A multi-dimensional accelerometer according to claim 1, characterized in that: The diaphragm (2) includes a polymer layer (21), a chromium plating layer (22) and a silver plating layer (23). The polymer layer (21) undergoes elastic deformation under extrusion. The chromium plating layer (22) is sandwiched between the polymer layer (21) and the silver plating layer (23), and the silver plating layer (23) faces the optical fiber ferrule (3).

8. A multi-dimensional accelerometer according to claim 7, characterized in that: The sensitivity and resonance frequency of the multi-dimensional accelerometer are adjusted by adjusting the thickness of the polymer layer (21) or the thickness of the silver plating layer (23).

9. A multi-dimensional accelerometer according to claim 8, characterized in that: The thickness of the polymer layer (21) is in an inverse proportional relationship with the sensitivity of the multi-dimensional accelerometer, and the thickness of the polymer layer (21) is in a direct proportional relationship with the resonance frequency of the multi-dimensional accelerometer.

10. A multi-dimensional accelerometer according to claim 8, characterized in that: The thickness of the silver plating layer (23) is in an inverse proportional relationship with the sensitivity of the multi-dimensional accelerometer, and the thickness of the silver plating layer (23) is in a direct proportional relationship with the resonance frequency of the multi-dimensional accelerometer.

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