阅读说明：本技术 一种适合低频的宽带高灵敏度扭转型压电加速度计 (Broadband high-sensitivity torsion type piezoelectric accelerometer suitable for low frequency ) 是由 刘爽 蓝宇 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种适合低频的宽带高灵敏度扭转型压电加速度计,属于压电加速度计技术领域。本发明为了满足现有水声工程领域低频结构振动和声场测量用高性能加速度计需求,提供一种适合于低频测量的高灵敏度扭转型压电加速度计。本发明综合利用压电陶瓷厚度剪切大的压电常数和悬臂梁结构的惯性力放大特性,实现在小尺寸条件下提升加速度计在低频段的灵敏度,在水下低频振动测试时,可减小传感器质量对待测件的振动特性影响。此外,还可为矢量水听器研制提供高性能加速度计,以减小低频用矢量水听器体积。(The invention discloses a broadband high-sensitivity torsion type piezoelectric accelerometer suitable for low frequency, and belongs to the technical field of piezoelectric accelerometers. The invention provides a high-sensitivity torsion type piezoelectric accelerometer suitable for low-frequency measurement, which aims to meet the requirements of high-performance accelerometers for low-frequency structural vibration and sound field measurement in the field of existing underwater sound engineering. The invention comprehensively utilizes the piezoelectric constant of large thickness shearing of piezoelectric ceramics and the inertia force amplification characteristic of a cantilever beam structure, realizes the improvement of the sensitivity of the accelerometer in a low frequency band under the condition of small size, and can reduce the influence of the mass of the sensor on the vibration characteristic of a piece to be tested during the underwater low-frequency vibration test. In addition, a high-performance accelerometer can be developed for the vector hydrophone, so that the volume of the vector hydrophone for low frequency is reduced.)

1. The broadband high-sensitivity torsion type piezoelectric accelerometer suitable for low frequency is characterized by comprising a first piezoelectric ceramic ring (1), a second piezoelectric ceramic ring (2), an inertia mass block (3), a screw (4), a first supporting piece (5), a second supporting piece (6) and a base (7), wherein the first supporting piece (5), the first piezoelectric ceramic ring (1), the inertia mass block (3), the second piezoelectric ceramic ring (2) and the second supporting piece (6) are sequentially and tightly sleeved on the screw (4), and two ends of the screw (4) are respectively installed at two ends of a strip-shaped base (7) through the first supporting piece (5) and the second supporting piece (6);

insulating sheets are respectively arranged on the upper electrode surface and the lower electrode surface of the first piezoelectric ceramic ring (1) and the second piezoelectric ceramic ring (2);

the polarization directions of the first piezoelectric ceramic ring (1) and the second piezoelectric ceramic ring (2) are tangential directions of the circumferences of the circular rings.

2. A broadband high sensitivity twisted piezoelectric accelerometer for low frequencies according to claim 1, wherein the inertial mass (3) comprises a ring-shaped connecting part (17) and an extension part (16), the ring-shaped connecting part (17) tightly fitting over the screw (4).

3. A broadband high sensitivity twisted piezoelectric accelerometer for low frequencies according to claim 2, in which the extension (16) is in the form of a long rod or arm.

4. A broadband high sensitivity twisted piezoelectric accelerometer for low frequencies according to claim 2, in which the extension (16) and the loop (17) are made of metals or alloys of different materials.

5. The broadband high-sensitivity twisted piezoelectric accelerometer according to claim 4, wherein the annular connecting portion (17) is made of aluminum alloy or steel, and the protruding portion (16) is made of high-density alloy.

6. A broadband high sensitivity twisted piezoelectric accelerometer for low frequencies according to claim 1, wherein the first (1) and second (2) piezo-ceramic rings are connected in series.

7. The broadband high-sensitivity torsion type piezoelectric accelerometer according to claim 6, wherein the upper electrode surface of the first piezoelectric ceramic ring (1) is used as a ground terminal, the lower electrode surface of the first piezoelectric ceramic ring (1) is connected with the lower electrode surface of the second piezoelectric ceramic ring (2), and the upper electrode surface of the second piezoelectric ceramic ring (2) is used as a signal output electrode.

8. A broadband high sensitivity twisted piezoelectric accelerometer for low frequencies according to claim 1, wherein the first (1) and second (2) piezo-ceramic rings are connected in parallel.

9. The broadband high-sensitivity twisted piezoelectric accelerometer for low frequency according to claim 8, wherein the upper electrode surface of the first piezoceramic ring (1) is connected to the lower electrode surface of the second piezoceramic ring (2) as a ground terminal, and the lower electrode surface of the first piezoceramic ring (1) is connected to the upper electrode surface of the second piezoceramic ring (2) as a signal output electrode.

Technical Field

The invention relates to a broadband high-sensitivity torsion type piezoelectric accelerometer suitable for low frequency, and belongs to the technical field of piezoelectric accelerometers.

Background

The piezoelectric accelerometer is widely used as an inertial sensor and plays an important role in the fields of vibration measurement, inertial navigation, underwater sound measurement and the like. Because the piezoelectric ceramic is used as a sensitive element, compared with other types of accelerometers, the piezoelectric ceramic accelerometer has the advantages of wide use frequency band, high sensitivity, high signal-to-noise ratio, convenience in installation, simple structure, convenience in manufacture, high reliability and the like.

For low frequency accelerations, measurements are typically made using a bending type accelerometer or a shear type accelerometer. Among them, although the bending type accelerometer has high sensitivity, its frequency response range is usually narrow and its overshoot capability is poor. Although the shear type accelerometer has a wider operating frequency band and better stability, the sensitivity is lower than that of the bending type accelerometer under the same size and quality, and the shear type accelerometer usually sacrifices the operating bandwidth in order to improve the low-frequency sensitivity. At present, measurement in the field of underwater acoustic engineering is increasingly focused on low-frequency measurement, such as ship shell vibration, vector hydrophone internal sensitive elements and the like, which are all required to be suitable for low-frequency measurement, and the accelerometer has the advantages of wide band, high sensitivity, small volume and light weight. At present, no matter the bending type accelerometer or the shearing type acceleration can not meet the requirement at the same time, and the improvement of the low-frequency measurement capability in the field of underwater acoustic engineering is influenced. Therefore, it is necessary to provide a broadband high-sensitivity accelerometer suitable for low frequencies.

Disclosure of Invention

The invention provides a high-sensitivity torsion type piezoelectric accelerometer suitable for low-frequency measurement, which aims to meet the requirements of high-performance accelerometers for low-frequency structural vibration and sound field measurement in the field of existing underwater sound engineering.

The technical scheme of the invention is as follows:

the utility model provides a high sensitivity torsion type piezoelectric accelerometer suitable for low frequency measurement, includes first piezoceramics ring 1, second piezoceramics ring 2, inertial mass piece 3, screw rod 4, first support piece 5, second support piece 6 and base 7, first support piece 5, first piezoceramics ring 1, inertial mass piece 3, second piezoceramics ring 2 and second support piece 6 closely suit in proper order on screw rod 4 to the both ends of screw rod 4 are installed at the both ends of strip base 7 through first support piece 5 and second support piece 6 respectively.

Further, it is limited that the upper electrode surface and the lower electrode surface of the first piezoceramic ring 1 and the second piezoceramic ring 2 are respectively provided with an insulation sheet.

Further, the polarization directions of the first piezoceramic ring 1 and the second piezoceramic ring 2 are both tangential to the circumference of the circular ring.

Further, the inertial mass 3 comprises an annular connection 17 and an extension 16, the annular connection 17 being mounted on the screw 4.

More particularly, the extension 16 is in the form of a long rod or arm.

Further, the protruding portion 16 and the annular connecting portion 17 are made of different metals or alloys.

Further, the material of the annular connecting portion 17 is preferably aluminum alloy or steel.

More specifically, the material of the protruding portion 16 is a high-density alloy.

Further defined, the first piezoceramic ring 1 and the second piezoceramic ring 2 are connected in series.

Further, it is limited that the upper electrode surface of the first piezoelectric ceramic ring 1 is used as a ground terminal, the lower electrode surface of the first piezoelectric ceramic ring 1 is connected to the lower electrode surface of the second piezoelectric ceramic ring 2, and the upper electrode surface of the second piezoelectric ceramic ring 2 is used as a signal output electrode.

Further defined, the first piezoceramic ring 1 and the second piezoceramic ring 2 are connected in parallel.

Further, the upper electrode surface of the first piezoelectric ceramic ring 1 is connected to the lower electrode surface of the second piezoelectric ceramic ring 2 as a ground terminal, and the lower electrode surface of the first piezoelectric ceramic ring 1 is connected to the upper electrode surface of the second piezoelectric ceramic ring 2 as a signal output electrode.

The invention has the following beneficial effects: the invention provides a novel accelerometer structure based on piezoelectric ceramic torsional motion and combined with a cantilever beam lever amplification principle, so that the low-frequency sensitivity of a piezoelectric accelerometer is improved under a small-size condition, and the influence of the mass of a sensor on the vibration characteristic of a to-be-tested piece can be reduced during underwater low-frequency vibration test. Meanwhile, a high-performance accelerometer can be developed for the vector hydrophone, so that the volume of the vector hydrophone for low frequency is reduced.

Drawings

FIG. 1 is a schematic view of an accelerometer configuration in which the extension is elongated;

FIG. 2 is a schematic view of an accelerometer configuration with an elongated arm;

FIG. 3 is a schematic view of a first piezoceramic ring being tangentially polarised;

FIG. 4 is a schematic view of a second piezoceramic ring being tangentially polarised;

FIG. 5 is a schematic structural view of an inertial mass;

FIG. 6 is a graph of the sensitivity of the accelerometer of example 2;

in the figure, 1-a first piezoceramic ring, 2-a second piezoceramic ring, 3-an inertial mass, 4-a screw, 5-a first support, 6-a second support, 7-a base, 9-an upper electrode surface of the first piezoceramic ring, 10-a lower electrode surface of the first piezoceramic ring, 13-an upper electrode surface of the second piezoceramic ring, 14-a lower electrode surface of the second piezoceramic ring, 16-an extension, 17-an annular connecting part.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The experimental procedures used in the following examples are conventional unless otherwise specified. The materials, reagents, methods and apparatus used, unless otherwise specified, are conventional in the art and are commercially available to those skilled in the art.

Example 1:

as shown in fig. 1, the accelerometer includes a first piezoceramic ring 1, a second piezoceramic ring 2, an inertial mass block 3, a screw 4, a first support member 5, a second support member 6 and a base 7, wherein the first support member 5, the first piezoceramic ring 1, the inertial mass block 3, the second piezoceramic ring 2 and the second support member 6 are sequentially and tightly sleeved on the screw 4, and two ends of the screw 4 are respectively installed on the base 7 through the first support member 5 and the second support member 6; insulating sheets are respectively arranged on the upper electrode surface and the lower electrode surface of the first piezoelectric ceramic ring 1 and the second piezoelectric ceramic ring 2; the polarization direction of the first piezoelectric ceramic ring 1 and the second piezoelectric ceramic ring 2 is the tangential direction of the circumference of the circular ring. So arranged, as shown in FIGS. 3 and 4, the first piezoceramic ring 1 and the second piezoceramic ringThe polarization directions of the rings 2 are tangential directions along the circumference, namely theta directions, when the electrodes are an upper plane and a lower plane of piezoelectric ceramics, the electrodes are electrified, and the first piezoelectric ceramic ring 1 and the second piezoelectric ceramic ring 2 generate thickness shearing movement, namely generate torsion movement. Due to the force-electricity reversibility of the piezoelectric ceramics, when the piezoelectric ceramics generate torsional motion, corresponding charges are generated on the surface of an electrode, and the piezoelectric constant related to the motion is d₁₅The quantity of electric charge output is the torsional force acting on the surface of the piezoelectric ceramic and d₁₅The product of (a). Meanwhile, as another important element affecting the sensitivity of the piezoelectric accelerometer, the inertial mass 3 is usually in direct contact with the sensitive element, and the inertial force applied to the inertial mass is mg which is the product of the mass and the acceleration of gravity, while the torsional force applied to the surface of the piezoelectric ceramic through the cantilever beam structure is mg which is gamma times, that is, the charge quantity Q is gamma mgd₁₅. Having a charge sensitivity of S_q＝γm d₁₅Voltage sensitivity of S_v＝S_q/C₀. Wherein C is₀Is static capacitance between the piezoelectric circular ceramic plate electrodes. That is to say under the certain condition of quality piece, can realize enlargiing inertial force and promote accelerometer sensitivity through adjusting cantilever beam length.

The application provides an accelerometer structure compares in current crooked cantilever beam type accelerometer, with quality piece and sensing element's action point, the junction from sensing element tip and quality piece prolongs to the junction of sensing element inside with the quality piece, under the unchangeable condition of cantilever beam length and quality piece quality promptly, the inertia power magnification has been increased, accelerometer sensitivity has been promoted, simultaneously also avoided, prior art is through the mode that increases cantilever beam length or quality piece quality, improve accelerometer sensitivity, the cracked problem of cantilever beam that leads to easily.

As shown in fig. 5, the inertial mass 3 includes an annular connecting portion 17 and an extending portion 16, the annular connecting portion 17 is fitted around the screw 4, the extending portion 16 is in the shape of a long rod, and the extending portion 16 and the annular connecting portion 17 are made of metals or alloys of different materials. With the arrangement, the extension part 16 and the annular connecting part 17 are made of metals or alloys with different materials, so that the torsion acting on the piezoelectric ceramic can be increased, and the total mass of the accelerometer can be reduced.

The first piezoelectric ceramic ring 1 and the second piezoelectric ceramic ring 2 can be connected in two ways, so that when the base 7 is connected with the piece to be tested, the accelerometer and the piece to be tested vibrate together, and the accelerometer outputs an acceleration signal.

(1) The first piezoelectric ceramic ring 1 and the second piezoelectric ceramic ring 2 are connected in parallel, that is, the upper electrode surface 9 of the first piezoelectric ceramic ring is connected with the lower electrode surface 14 of the second piezoelectric ceramic ring as a ground terminal, and may or may not be connected with the base 7. The lower electrode surface 10 of the first piezoceramic ring is connected with the upper electrode surface 13 of the second piezoceramic ring as a signal output electrode. In this case, the capacitance of the accelerometer is the sum of the first piezo-ceramic ring 1 and the second piezo-ceramic ring 2, which can reduce the self-noise of the accelerometer, but the sensitivity is the same as the output with only one piezo-ceramic ring.

(2) The first piezoceramic ring 1 and the second piezoceramic ring 2 are connected in series, i.e. the upper electrode face 9 of the first piezoceramic ring serves as a ground terminal and may or may not be connected to the base 7. The lower electrode surface 10 of the first piezoelectric ceramic ring is connected with the lower electrode surface 14 of the second piezoelectric ceramic ring, and the upper electrode surface 13 of the second piezoelectric ceramic ring is a signal output electrode. The sensitivity of the accelerometer is now 2 times that of the above parallel connection.

Example 2:

as shown in fig. 2, in the present embodiment, the extension 16 has a long arm shape, and the first piezoceramic ring 1 and the second piezoceramic ring 2 are connected in series.

When the inertia mass block 3 swings up and down in the vibration process to generate inertia force, the inertia force is amplified by a lever and acts on the lower electrode surface 10 of the first piezoelectric ceramic ring and the upper electrode surface 13 of the second piezoelectric ceramic ring, and at the moment, the upper electrode surface 9 of the first piezoelectric ceramic ring and the lower electrode surface 14 of the second piezoelectric ceramic ring are respectively connected with the first support piece 5 and the second support piece 6 in a locking manner through insulating pieces to form a fixed constraint boundary which can be regarded as a fixed boundary condition. Therefore, a torsional motion is generated in the first piezoceramic ring 1 and the second piezoceramic ring 2, and an electrical signal is output at the signal end through the reverse piezoelectric effect, which is proportional to the acceleration.

The extension 16 of the inertia mass block 3 is made of high-density alloy, the annular connecting portion 17 is made of aluminum alloy or steel, and when the inertia mass block moves, compared with the traditional inertia mass block 3 made of high-density alloy, the deformation caused by piezoelectric ceramics is larger, and the signal is promoted.

In order to verify the performance of the accelerometer of this embodiment, fig. 6 shows a sensitivity curve of the accelerometer, and as can be seen from fig. 6, the voltage sensitivity of the accelerometer is 4.63V/g (the sensitivity is a sensitivity value without amplification factor), the resonant frequency is 3551Hz, and the upper limit working frequency of 3dB can reach 1775 Hz.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.