Dynamic adjustable acceleration sensor with high sensitivity and low noise

Abstract

The invention discloses a dynamic adjustable acceleration sensor with high sensitivity and low noise, and relates to the field of acceleration sensors. According to the acceleration sensor, a plurality of cantilever beam supporting sheets are stacked in sequence and are connected with a base; a piezoelectric element is fixed in a central circular area of the cantilever beam supporting sheet on the topmost layer, a plurality of mass sheets are sequentially stacked in an outer ring girdle area, longitudinal excitation deformation is easily conducted to the piezoelectric sheet, and stress is concentrated at the joint of the cantilever beam supporting sheet on the bottommost layer and the base under the condition of transverse excitation, so that the directivity of the acceleration sensor is better, and the stability of the acceleration sensor is improved. The charge output in the horizontal direction is small; the detachable assembly of the cantilever beam supporting sheet and the mass sheet is beneficial for improving the adjustability of performance parameters and the phase amplitude consistency in array application, and the high-sensitivity adjustable structural design and the collaborative optimization design of material physical property parameters jointly achieve high sensitivity, excellent bandwidth adjustability and extremely low background noise. The method is suitable for complex underwater sound environments such as hydrophone arrays.

Description

TECHNICAL FIELD

[0001] The application relates to the field of acceleration sensors, in particular to a high-sensitivity low-noise dynamic adjustable acceleration sensor. BACKGROUND

[0002] An acceleration sensor is an inertial sensor for acceleration measurement, which is widely used in the fields of automobile industry, sports measurement, ocean science, biomedicine, etc. In particular, with the rise of ocean exploration, the demand for high-performance underwater acoustic detection equipment is increasingly urgent. As a core component of an inertial vector hydrophone, a high-sensitivity low-noise acceleration sensor has also attracted widespread attention in the field of underwater acoustics. The inertial vector hydrophone synchronously obtains the sound pressure and particle velocity vector information at the location by packaging the acceleration sensor in a neutral buoyancy spherical shell based on the principle of rigid shell oscillation in the sound field. The inertial vector hydrophone has natural dipole directivity and the ability to suppress isotropic environmental noise, and can realize low-frequency acoustic detection of a small-aperture array (such as a multipole vector array).

[0003] In the underwater acoustic detection scene such as a sonar system, a plurality of inertial vector hydrophones are usually arranged in a specific array form to form a hydrophone array. Through joint analysis of the signals detected by the inertial vector hydrophones at different positions in the hydrophone array, a data source can be provided for a beamforming algorithm to realize directional detection.

[0004] Optimizing the detection performance of the hydrophone array directly affects the detection accuracy and imaging reliability of the sonar system. The detection performance of the hydrophone array is not only affected by the inherent performance parameters (such as sensitivity, self-noise, etc.) of a single inertial vector hydrophone, but also affected by the consistency design between different inertial vector hydrophones. As the core component of each inertial vector hydrophone in the hydrophone array, the inherent performance parameters of the inertial vector hydrophone and the consistency design between the inertial vector hydrophones are mainly affected by the acceleration sensor. Therefore, developing a high-performance acceleration sensor is very important for optimizing the detection performance of the hydrophone array, and has become one of the urgent needs in the field of underwater acoustics. SUMMARY

[0005] In view of the above problems and technical needs, the application provides a high-sensitivity low-noise dynamic adjustable acceleration sensor. The technical scheme of the application is as follows:

[0006] The high-sensitivity low-noise dynamic adjustable acceleration sensor comprises a packaging shell, a plurality of cantilever beam support pieces, a plurality of mass pieces, a piezoelectric element, and a measurement circuit. The packaging shell, the cantilever beam support pieces, and the mass pieces are all made of metal materials. The piezoelectric element comprises a piezoelectric piece and an electrode piece.

[0007] The packaging shell is in a cylindrical structure and has a cavity inside, and the plurality of cantilever beam support pieces, the plurality of mass pieces, the piezoelectric element and the measurement circuit are arranged in the cavity inside the packaging shell; the plurality of cantilever beam support pieces are sequentially stacked, the lower surface of the cantilever beam support piece located at the bottom layer along the axial direction is fixed to the inner wall of the bottom surface of the packaging shell, a plurality of mass pieces are sequentially stacked in the outer ring belt region of the upper surface of the cantilever beam support piece located at the top layer along the axial direction, and the plurality of cantilever beam support pieces and the plurality of mass pieces stacked along the axial direction are detachably installed together.

[0008] The piezoelectric element is fixed to the central circular region of the upper surface of the cantilever beam support piece located at the top layer which is not covered by the mass piece, and the piezoelectric element, the cantilever beam support piece and the packaging shell are coaxial; the high-sensitivity low-noise dynamic adjustable acceleration sensor is fastened to the excitation source through the outer wall of the bottom surface of the packaging shell.

[0009] The electrode piece in the piezoelectric element is electrically connected to the measurement circuit, the piezoelectric charge coefficient d 33 or d 31 of the piezoelectric piece in the piezoelectric element is greater than 1000 pC / N, the piezoelectric voltage coefficient g 33 or g 31 of the piezoelectric piece in the piezoelectric element is greater than 50×10 -3 Vm / N, and the dielectric loss tan δ is less than 1%.

[0010] Further, the piezoelectric material used in the piezoelectric piece in the piezoelectric element is lead zirconate titanate ceramic, relaxor ferroelectric single crystal, lead-free perovskite piezoelectric ceramic, bismuth layer piezoelectric ceramic or textured ceramic.

[0011] Further, each cantilever beam support piece is in a circular disc structure and has the same circumferential specification, four slit grooves are formed in the circumferential direction of each cantilever beam support piece, the four slit grooves are uniformly and symmetrically distributed in the circumferential direction of the cantilever beam support piece, the slotting depth direction of each slit groove is along the radial direction of the cantilever beam support piece, the four slit grooves divide the outer ring belt region of the cantilever beam support piece into four annular connection segments, and each annular connection segment is provided with an assembly hole; the slit grooves and the assembly holes of the plurality of cantilever beam support pieces stacked along the axial direction are distributed and aligned, and an assembly member is arranged in the assembly holes of the plurality of cantilever beam support pieces to detachably install the plurality of cantilever beam support pieces.

[0012] Further, each mass piece is in 1 / 4 ring structure and has the same circumferential specification, the size of each mass piece is consistent with the size of each annular connecting segment in the outer ring belt area of each cantilever beam support piece, and each mass piece is provided with an assembly hole; the mass pieces are sequentially stacked at one annular connecting segment in the outer ring belt area of the cantilever beam support piece, the assembly hole on the mass piece is aligned with the assembly hole on the annular connecting segment of the cantilever beam support piece, and an assembly part is arranged in the assembly holes of the mass pieces and the cantilever beam support pieces to detachably install the mass pieces and the cantilever beam support pieces.

[0013] Further, the piezoelectric sheet in the piezoelectric element is made of textured ceramics, the piezoelectric charge coefficient d 33 = 1228 pC / N, the piezoelectric voltage coefficient g 33 = 50 x 10 -3 Vm / N, and the dielectric loss tan delta = 0.5%; the sensitivity of the high-sensitivity low-noise dynamic adjustable acceleration sensor reaches 1713 pC / g, the equivalent noise acceleration at 100 Hz is 16.8 ng / Hz 1 / 2 , and the equivalent noise acceleration at 1000 Hz is 10.2 ng / Hz 1 / 2 .

[0014] Further, the packaging shell comprises a base and a shell made of metal material, the base is circular in radial section, the shell is open-cylindrical, the opening of the shell is packaged with the base to form the packaging shell, the base and the shell are coaxial and form the axis of the packaging shell; one side surface of the base inside the packaging shell faces the shell and is fixed with the cantilever beam support piece of the bottom layer, one side surface of the shell inside the packaging shell opposite to the base is provided with a clamping groove, and the measurement circuit is fixed in the clamping groove.

[0015] Further, the base comprises a circular plate body and a cylindrical boss, the boss extends outward on one side surface of the plate body in the thickness direction, and the plate body and the boss are coaxial; the radial dimension of the boss is smaller than the radial dimension of the central circular area of the upper surface of the cantilever beam support piece of the top layer, the boss of the base is located in the internal cavity of the packaging shell, and the end surface of the boss of the base is fixed with the cantilever beam support piece of the bottom layer.

[0016] Further, the base has a first threaded groove extending from the end surface of the boss to the plate body at the axis, the lower surface of the cantilever beam support piece of the bottom layer has a bolt protruding outward at the axis, and the bolt on the lower surface of the cantilever beam support piece of the bottom layer is assembled in the first threaded groove on the base to fasten the cantilever beam support piece of the bottom layer with the base.

[0017] Further, the base further has a second threaded groove extending from the other side surface of the plate body part to the boss part at the axis, and the high-sensitivity low-noise dynamic adjustable acceleration sensor is fixed with the excitation source through the second threaded groove on the base.

[0018] Further, the piezoelectric element is bonded with the upper surface of the cantilever beam support sheet of the topmost layer through epoxy resin.

[0019] The application has the following beneficial technical effects:

[0020] The application discloses a high-sensitivity low-noise dynamic adjustable acceleration sensor, which is stacked and connected with a base by a plurality of cantilever beam support sheets and a plurality of mass sheets, and a piezoelectric element is fixed on the upper surface of the cantilever beam support sheet of the topmost layer in a central circular area not covered by the mass sheet. The longitudinal excitation deformation is easily conducted to the piezoelectric sheet in the piezoelectric element, and the stress is concentrated at the connection between the cantilever beam support sheet of the bottommost layer and the base under the transverse excitation condition, so that the directivity of the high-sensitivity low-noise dynamic adjustable acceleration sensor is better, the horizontal direction charge output is small, and the overall directivity is stronger. The high-sensitivity adjustable structure design is combined with the material physical parameter optimization design of the high-piezoelectric charge coefficient, the high-piezoelectric voltage coefficient and the low dielectric loss, so as to not only improve the sensitivity of the acceleration sensor, but also further improve the directivity of the sensor and effectively reduce the background noise of the acceleration sensor, so that the inertial vector hydrophone made of the acceleration sensor has better performance parameters. The detachable mounting structure of the cantilever beam support sheet and the mass sheet can conveniently and quickly adjust the stacking quantity to finely adjust the performance of the acceleration sensor, and facilitate the amplitude and phase consistency design of different inertial vector hydrophones in the hydrophone array. The design makes the acceleration sensor have high sensitivity, excellent bandwidth adjustable ability and extremely low background noise, significantly improves the adjustability of the performance parameters of the sensor and the amplitude and phase consistency in the array application. These characteristics make the acceleration sensor particularly suitable for complex underwater acoustic environments with extremely high consistency requirements for sensors, such as hydrophone arrays, can provide higher quality data sources for beamforming algorithms, and further improve the detection accuracy and imaging reliability of the sonar system.

[0021] The high-sensitivity low-noise dynamic adjustable acceleration sensor maximizes the utilization rate of the internal limited space in the structure, optimizes the material intrinsic property, and reduces the equivalent noise acceleration of the sensor. In combination with a low-power and low-noise special charge amplification circuit, the overall performance of the piezoelectric sensor is effectively improved, and the final sensitivity can reach 1713 pC / g, and the equivalent noise acceleration at 100 Hz is 16.8 ng / Hz. 1 / 2, the equivalent noise acceleration at 1000Hz is 10.2ng / Hz 1 / 2 . BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is an axial sectional view of a high-sensitivity low-noise dynamic adjustable acceleration sensor in an embodiment of the present application.

[0023] Figure 2 is a view along the axial direction of a laminated structure formed by the plurality of cantilever beam support pieces 210 and the plurality of mass pieces 220 in an embodiment of the present application.

[0024] Figure 3 is a structural schematic diagram of a single cantilever beam support piece in an embodiment of the present application.

[0025] Figure 4 is a structural schematic diagram of a single mass piece in an embodiment of the present application.

[0026] Figure 5 is a comparison chart of sensitivity test result data when the same high-sensitivity structure is combined with different material physical property parameters in a test example.

[0027] Figure 6 is Figure 5 is a comparison chart of noise equivalent acceleration test result data when the same high-sensitivity structure is combined with different material physical property parameters in a test example. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application will be further described below with reference to the accompanying drawings.

[0029] The present application discloses a high-sensitivity low-noise dynamic adjustable acceleration sensor, please refer to Figure 1 The high-sensitivity low-noise dynamic adjustable acceleration sensor includes a packaging shell 100, a plurality of cantilever beam support pieces 210, a plurality of mass pieces 220, a piezoelectric element 300, and a measurement circuit 400.

[0030] The packaging shell 100, the cantilever beam support piece 210, and the mass piece 220 are all made of metal material, and in an embodiment, the metal material used is stainless steel material.

[0031] The packaging shell 100 is in a cylindrical structure and has a cavity inside. In an embodiment, in order to facilitate assembly, the packaging shell 100 adopts an assembly structure, and the packaging shell 100 comprises a base 110 and a shell 120, both of which are made of metal material. The base 110 is circular in radial cross-section, and the shell 120 is open-cylindrical. The opening of the shell 120 is packaged with the base 110 to form the packaging shell 100. The shell 120 and the base 110 form the cavity inside the packaging shell 100. The base 110 and the shell 120 are coaxial and form the axis of the entire packaging shell 100. The base 110 forms the bottom surface of the entire packaging shell 100, and the end surface of the shell 120 opposite to the base 100 in the axial direction forms the top surface of the entire packaging shell 100.

[0032] The plurality of cantilever beam support pieces 210, the plurality of mass pieces 220, the piezoelectric element 300, and the measurement circuit 400 are arranged in the cavity inside the packaging shell 100. The plurality of cantilever beam support pieces 210 are stacked in sequence, and the lower surface of the cantilever beam support piece at the bottommost layer in the axial direction is fixed to the inner wall of the bottom surface of the packaging shell. The cantilever beam support piece 210 and the packaging shell 100 are coaxial, Figure 1 For example, eight cantilever beam support pieces 210 are stacked in sequence along the axial direction. The outer ring belt area of the upper surface of the cantilever beam support piece at the topmost layer in the axial direction also stacks a plurality of mass pieces 220 in sequence, as shown in Figure 1 For example, three mass pieces 220 are stacked. The plurality of cantilever beam support pieces 210 and the plurality of mass pieces 220 stacked in sequence along the axial direction are detachably installed together. The detachable structure can facilitate and quickly adjust the number of layers of the cantilever beam support piece 210 and / or the number of layers of the mass piece 220. There is a gap between the mass piece 220 at the topmost layer in the axial direction and the top surface of the packaging shell 100. The radial dimension of the cantilever beam support piece 210 is smaller than the cavity dimension of the packaging shell 100, that is, there is a gap between the side wall of the cantilever beam support piece 210 and the cavity side wall of the packaging shell 100. The stacked structure of the plurality of cantilever beam support pieces 210 and the plurality of mass pieces 220 is fixed at one end along the axial direction, and the other end forms a free end.

[0033] The top view of the stacked structure of the plurality of cantilever beam support pieces 210 and the plurality of mass pieces 220 along the axial direction from the free end direction is shown in Figure 2 Figure 1 is a cross-sectional view along Figure 2 AA' section. Please refer to Figure 1 and Figure 2 The mass piece 220 is stacked on the outer ring belt area of the upper surface of the cantilever beam support piece 210 at the topmost layer in the axial direction. The central circular area of the upper surface of the cantilever beam support piece 210 at the topmost layer in the axial direction is not covered by the mass piece 220. The diameter D2 of the central circular area is smaller than the diameter D3 of the cantilever beam support piece 210.

[0034] ​Each cantilever beam support piece 210 is in a circular disc structure and has the same circumferential specification. The structure of a single cantilever beam support piece is shown in FIG. 2B. Four slit grooves 211 are formed in the circumferential direction of each cantilever beam support piece 210. The four slit grooves are uniformly and symmetrically distributed in the circumferential direction of the cantilever beam support piece 210. The slotting depth direction of each slit groove is along the radial direction of the cantilever beam support piece. The part of the cantilever beam support piece other than the central circular area with the central diameter D2 is an outer ring belt area. The four slit grooves 211 divide the outer ring belt area into four annular connection segments. An assembly hole 212 is formed in each annular connection segment. Figure 3

[0035] Each mass piece 220 is in a 1 / 4 circular ring structure and has the same circumferential specification. The structure of a single mass piece 220 is shown in FIG. 3B. The size of each mass piece is consistent with the size of each annular connection segment in the outer ring belt area of each cantilever beam support piece. An assembly hole 221 is formed in each mass piece 220. Figure 4

[0036] As shown in FIG. 4B, the assembly holes 221 on the mass pieces 220 and the assembly holes 212 on the annular connection segments of the cantilever beam support pieces 210 are aligned. The mass pieces 220 are sequentially stacked at one annular connection segment in the outer ring belt area of the cantilever beam support pieces 210. The assembly holes 221 on the mass pieces 220 are aligned with the assembly holes 212 on the annular connection segments of the cantilever beam support pieces 210. Assembly pieces are sequentially inserted into the assembly holes of the mass pieces 220 and the cantilever beam support pieces 210 to detachably install the mass pieces 220 and the cantilever beam support pieces 210. Figure 2

[0037] As shown in FIG. 5B, the diameter D1 of the piezoelectric element 300 is smaller than the diameter D2 of the central circular area of the upper surface of the topmost cantilever beam support piece 210. The piezoelectric element 300 is fixed at the central circular area of the upper surface of the topmost cantilever beam support piece which is not covered by the mass pieces. The piezoelectric element 300 is coaxial with the cantilever beam support pieces 210 and the packaging shell 100. In one embodiment, the piezoelectric element 300 is bonded to the upper surface of the topmost cantilever beam support piece by epoxy. The piezoelectric element 300 includes a piezoelectric sheet and an electrode sheet which are stacked together. The piezoelectric element 300 can have a common single-layer structure or a multi-layer series structure, which is not limited in the present application. Figure 2 The electrode sheet in the piezoelectric element 300 is electrically connected to a measurement circuit 400. The measurement circuit 400 is a charge amplification circuit, a voltage amplification circuit or a voltage follower circuit which is composed of low-noise electronic elements including resistors, capacitors and operational amplifiers. In one embodiment, the housing 120 has a clamping groove formed on the surface opposite to the base 110 inside the packaging shell 100. The measurement circuit 400 is fixed in the clamping groove.

[0038] ​​​​

[0039] When the base 110 is formed as the bottom surface of the entire package shell 100, the side surface of the base 110 inside the package shell 100, which is formed as the inner wall of the bottom surface of the entire package shell 100, is thus formed as the bottom surface of the entire package shell 100, and the bottommost cantilever beam support piece 210 is fixed on the side surface of the base 110 inside the package shell 100. In one embodiment as shown in Figure 1 The base 110 includes a circular plate body portion 111 and a cylindrical boss portion 112, which extends outward on the side surface of the plate body portion 111 in the thickness direction, and the plate body portion 111 and the boss portion 112 are coaxial. The plate body portion 111 has a stepped structure on the circumferential side surface of the plate body portion 111 in the thickness direction close to the boss portion 112, and the opening of the outer shell 120 is fixed at the stepped structure on the circumferential side of the plate body portion 111. The radial dimension of the boss portion 112 is smaller than the radial dimension of the central circular area of the cantilever beam support piece 210 and also smaller than the radial dimension of the piezoelectric element 300.

[0040] The boss portion 112 of the base 110 is located in the cavity inside the package shell 100, and the side end surface of the boss portion 112 of the base 110 close to the top surface of the package shell 100 is fixed together with the bottommost cantilever beam support piece 210. The bottommost cantilever beam support piece 210 is connected to the boss portion 112 of the base 110 by protruding bolts. In one implementation, the base 110 has a first threaded groove 113 extending from the end surface of the boss portion 112 to the plate body portion 111 at the axis, and the lower surface of the bottommost cantilever beam support piece 210 has bolts protruding outward at the axis, and the bolts on the lower surface of the bottommost cantilever beam support piece 210 are fitted into the first threaded groove 113 on the base 110, achieving fastening of the bottommost cantilever beam support piece 210 to the base 110.

[0041] In application, the high-sensitivity low-noise dynamic adjustable acceleration sensor is fastened to the excitation source through the bottom surface outer wall of the package shell 100. When the base 110 is formed as the bottom surface of the entire package shell 100, i.e., the other side surface of the plate body portion 111 of the base 110 in the thickness direction away from the boss portion 112 is fastened to the excitation source, and in order to facilitate fastening, the base 110 also has a second threaded groove 114 extending from the other side surface of the plate body portion 111 relative to the boss portion 112 to the boss portion 112 at the axis, and the high-sensitivity low-noise dynamic adjustable acceleration sensor is fixed together with the excitation source through the second threaded groove 114 on the base.

[0042] Based on the structure provided in the present application, when the high-sensitivity low-noise dynamic adjustable acceleration sensor follows the acceleration movement of the excitation source, the free end of the laminated structure formed by the plurality of cantilever beam support pieces 210 and the plurality of mass pieces 220 generates an inertial force opposite to the acceleration direction due to inertia, which drives the bending deformation at the topmost cantilever beam support piece 210, and the bending deformation at the topmost cantilever beam support piece 210 causes the piezoelectric piece attached thereto in the piezoelectric element 300 to be stretched or compressed accordingly. The positive and negative charges in the piezoelectric piece are separated due to the lattice deformation, thereby generating an electric charge signal on the electrode piece on the surface of the piezoelectric piece, which is proportional to the strain on the beam, i.e., the size of the acceleration. The weak electric charge signal is finally converted into a low-impedance voltage signal output through the low-noise measurement circuit 400, completing the conversion from acceleration to electric signal.

[0043] In the high-sensitivity low-noise dynamic adjustable acceleration sensor, the plurality of cantilever beam support pieces 210 and the plurality of mass pieces 220 are laminated and fastened together, and the protruding bolt connection base is adopted, so that the directivity of the high-sensitivity low-noise dynamic adjustable acceleration sensor is better, and the longitudinal excitation deformation is easily conducted to the piezoelectric piece in the piezoelectric element 300, while the stress is concentrated at the connecting bolt between the bottommost cantilever beam support piece 210 and the base under the transverse excitation condition, the horizontal direction charge output is small, and the overall directivity is stronger.

[0044] In order to optimize the effective receiving ability of the acceleration sensor for underwater weak signals, in addition to the high-sensitivity structure design described above, the material physical parameters need to be optimized in combination, so that the acceleration sensor has the characteristics of high sensitivity and low noise. The optimization design of the material physical parameters includes that the piezoelectric charge coefficient d 33 or d 31 of the piezoelectric piece in the piezoelectric element 300 is greater than 1000 pC / N, the piezoelectric voltage coefficient g 33 or g 31 is greater than 50×10 -3 Vm / N, and the dielectric loss tanδ is less than 1%. Based on meeting the design requirements of the material physical parameters, the piezoelectric material used for the piezoelectric piece in the piezoelectric element 300 is lead zirconate titanate ceramic, relaxor ferroelectric single crystal, lead-free perovskite piezoelectric ceramic, bismuth layer piezoelectric ceramic, or textured ceramic.

[0045] Preferably, the piezoelectric piece in the piezoelectric element 300 is made of textured ceramic, the piezoelectric charge coefficient d 33 = 1228 pC / N, and the piezoelectric voltage coefficient g 33 = 50×10 -3Vm / N, dielectric loss tan d = 0.5%. On this basis, by using the high-sensitivity structure and the synergistic design of the material physical property parameters, the sensitivity of the high-sensitivity low-noise dynamic adjustable acceleration sensor reaches 1713 pC / g, the equivalent noise acceleration at 100 Hz is 16.8 ng / Hz 1 / 2 , the equivalent noise acceleration at 1000 Hz is 10.2 ng / Hz 1 / 2 , has high directivity and low background noise, and is more suitable and reliable for application in complex situations such as underwater.

[0046] In one example, the piezoelectric sheet in the piezoelectric element 300 is designed to be a sheet with a diameter of 12.5 mm and a thickness of 1 mm using different material physical property parameters, and a test comparison is carried out in combination with the high-sensitivity structure design of the present application:

[0047] (1) In one experimental example, the piezoelectric sheet in the piezoelectric element 300 is prepared by tape casting using PIN-PSN-PT textured ceramics, the piezoelectric charge coefficient d 33 of the piezoelectric sheet = 1228 pC / N, the piezoelectric voltage coefficient g 33 = 50 x 10 -3 Vm / N, dielectric loss tan d = 0.5%.

[0048] (2) As Comparative Example 1, the piezoelectric sheet in the piezoelectric element 300 is prepared by solid phase method using PZT-5 piezoelectric ceramics, the piezoelectric charge coefficient d 33 of the piezoelectric sheet = 650 pC / N, the piezoelectric voltage coefficient g 33 = 21 x 10 -3 Vm / N, dielectric loss tan d = 2.2%.

[0049] (3) As Comparative Example 2, the piezoelectric sheet in the piezoelectric element 300 is prepared by solid phase method using PZT-4 piezoelectric ceramics, the piezoelectric charge coefficient d 33 of the piezoelectric sheet = 350 pC / N, the piezoelectric voltage coefficient g 33 = 21 x 10 -3 Vm / N, dielectric loss tan d = 0.6%.

[0050] (4) As Comparative Example 3, the piezoelectric sheet in the piezoelectric element 300 is prepared by solid phase sintering using PZT-8 piezoelectric ceramics, the piezoelectric charge coefficient d 33 of the piezoelectric sheet = 200 pC / N, the piezoelectric voltage coefficient g 33 = 17 x 10 -3 Vm / N, dielectric loss tan d = 0.3%.

[0051] The sensitivity test result data graph of the piezoelectric sheet under the design of the above four different material physical property parameters is as follows:Figure 5 The noise equivalent acceleration test result data graph is shown in Fig. 6. Figure 6 The resonant frequency point of the acceleration sensor in the experimental example is 2200 Hz, the sensitivity is 1713 pC / g, the equivalent noise acceleration at 100 Hz is 16.8 ng / Hz 1 / 2 , and the equivalent noise acceleration at 1000 Hz is 10.2 ng / Hz 1 / 2 . The resonant frequency point of the acceleration sensor in Comparative Example 1 is 2200 Hz, the sensitivity is 755 pC / g, the equivalent noise acceleration at 100 Hz is 45.9 ng / Hz 1 / 2 . The resonant frequency point of the acceleration sensor in Comparative Example 2 is 2350 Hz, the sensitivity is 547 pC / g, the equivalent noise acceleration at 100 Hz is 40.6 ng / Hz 1 / 2 . The resonant frequency point of the acceleration sensor in Comparative Example 3 is 2170 Hz, the sensitivity is 342 pC / g, the equivalent noise acceleration at 100 Hz is 42.4 ng / Hz 1 / 2 . The comparison results are shown in the following table:

[0052]

[0053] As can be seen from the comparison of the example, the piezoelectric sheet made of textured ceramic in the experimental example has high piezoelectric charge coefficient, high piezoelectric voltage coefficient and low dielectric loss. The material physical property parameter design combined with high sensitivity structure design can make the acceleration sensor have obvious advantages in sensitivity self-noise.

[0054] The above is only the preferred embodiment of the present application, and the present application is not limited to the above examples. It can be understood that other improvements and changes directly derived or thought by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A high-sensitivity low-noise dynamic adjustable acceleration sensor, characterized by, The high-sensitivity low-noise dynamic adjustable acceleration sensor comprises a packaging shell, a plurality of cantilever beam support pieces, a plurality of mass pieces, a piezoelectric element and a measuring circuit, the packaging shell, the cantilever beam support pieces and the mass pieces are all made of metal materials, and the piezoelectric element comprises a piezoelectric piece and an electrode piece. The packaging shell is in a cylindrical structure and has a cavity inside, the plurality of cantilever beam support pieces, the plurality of mass pieces, the piezoelectric element and the measuring circuit are arranged in the cavity inside the packaging shell; the plurality of cantilever beam support pieces are sequentially stacked, the lower surface of the cantilever beam support piece at the bottom layer is fixed to the inner wall of the bottom surface of the packaging shell along the axial direction, a plurality of mass pieces are sequentially stacked in the outer ring belt area of the upper surface of the cantilever beam support piece at the top layer along the axial direction, and the plurality of cantilever beam support pieces and the plurality of mass pieces stacked along the axial direction are detachably installed together. The piezoelectric element is fixed to the central circular area of the upper surface of the cantilever beam support piece at the top layer which is not covered by the mass piece, and the piezoelectric element, the cantilever beam support piece and the packaging shell are coaxial; the high-sensitivity low-noise dynamic adjustable acceleration sensor is fastened with the excitation source through the outer wall of the bottom surface of the packaging shell. The electrode pieces in the piezoelectric element are electrically connected to the measuring circuit, the piezoelectric charge coefficient d 33 or d 31 of the piezoelectric pieces in the piezoelectric element is greater than 1000 pC / N 33 or g 31 The piezoelectric voltage coefficient g -3 of the piezoelectric pieces in the piezoelectric element is greater than 50 x 10 Vm / N, and the dielectric loss tan δ is less than 1%.

2. The high sensitivity low noise dynamically tunable acceleration sensor of claim 1, wherein, The piezoelectric material used in the piezoelectric piece in the piezoelectric element is lead zirconate titanate ceramic, relaxor ferroelectric single crystal, lead-free perovskite piezoelectric ceramic, bismuth layer piezoelectric ceramic or textured ceramic.

3. The high sensitivity low noise dynamically tunable acceleration sensor of claim 1, wherein, Each cantilever beam support piece is in a circular disc structure and has the same circumferential specification, four slit grooves are formed in the circumferential direction of each cantilever beam support piece, the four slit grooves are uniformly and symmetrically distributed in the circumferential direction of the cantilever beam support piece, the slotting depth direction of each slit groove is along the radial direction of the cantilever beam support piece, the four slit grooves divide the outer ring belt area of the cantilever beam support piece into four annular connection sections, and an assembly hole is formed in each annular connection section; the slit grooves and the assembly holes of the plurality of cantilever beam support pieces stacked along the axial direction are distributed and aligned, and an assembly part is arranged in the assembly holes of the plurality of cantilever beam support pieces to detachably install the plurality of cantilever beam support pieces.

4. The high sensitivity low noise dynamically tunable acceleration sensor of claim 3, wherein, Each mass piece is in a 1 / 4 circular ring structure and has the same circumferential specification, the size of each mass piece is consistent with the size of each annular connection section in the outer ring belt area of each cantilever beam support piece, and an assembly hole is formed in each mass piece. The mass pieces are sequentially stacked at the annular connection sections in the outer ring belt area of the cantilever beam support piece, the assembly holes in the mass pieces are aligned with the assembly holes in the annular connection sections of the cantilever beam support piece, and an assembly part is arranged in the assembly holes of the mass pieces and the cantilever beam support piece to detachably install the mass pieces and the cantilever beam support piece.

5. The high sensitivity low noise dynamically tunable acceleration sensor of claim 4, wherein, The piezoelectric sheet in the piezoelectric element is made of textured ceramic, piezoelectric charge coefficient d 33 =1228pC / N, piezoelectric voltage coefficient g 33 =50×10 -3 Vm / N, dielectric loss tanδ=0.5%; the sensitivity of the high-sensitivity low-noise dynamic adjustable acceleration sensor reaches 1713pC / g, the equivalent noise acceleration at 100Hz is 16.8ng / Hz 1 / 2 , the equivalent noise acceleration at 1000Hz is 10.2ng / Hz 1 / 2 .

6. The high sensitivity low noise dynamically tunable acceleration sensor of claim 1, wherein, The packaging shell comprises a base and a shell made of metal materials, the base is in a circular shape in the radial cross section, the shell is in an open cylindrical shape, the opening of the shell is packaged with the base to form the packaging shell, the base and the shell are coaxial and form the axis of the packaging shell; one side surface of the base inside the packaging shell faces the shell and is fixed with the cantilever beam support piece at the bottom layer, one side surface of the shell inside the packaging shell opposite to the base is provided with a clamping groove, and the measuring circuit is fixed in the clamping groove.

7. The high sensitivity low noise dynamically tunable acceleration sensor of claim 6, wherein, The base comprises a circular plate body part and a cylindrical boss part, the boss part extends outward on one side surface of the plate body part in the thickness direction, and the plate body part and the boss part are coaxial; the radial dimension of the boss part is smaller than the radial dimension of the central circular area of the upper surface of the topmost cantilever beam support sheet, the boss part of the base is located in the internal cavity of the package shell, and the end surface of the boss part of the base is fixed with the bottommost cantilever beam support sheet.

8. The high-sensitivity low-noise dynamic adjustable acceleration sensor according to claim 7, wherein, The base has a first threaded groove extending from the end surface of the boss part to the plate body part at the axis, the bottom surface of the bottommost cantilever beam support sheet has a bolt protruding outward at the axis, and the bolt on the bottom surface of the bottommost cantilever beam support sheet is fitted in the first threaded groove on the base to realize the fastening of the bottommost cantilever beam support sheet and the base.

9. The high sensitivity low noise dynamically tunable acceleration sensor of claim 7, wherein, The base also has a second threaded groove extending from the other side surface of the plate body part to the boss part at the axis, and the high-sensitivity low-noise dynamic adjustable acceleration sensor is fixed with the excitation source through the second threaded groove on the base.

10. The high sensitivity low noise dynamically tunable acceleration sensor of claim 1, wherein, The piezoelectric element is bonded with the upper surface of the topmost cantilever beam support sheet by epoxy resin.

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