阅读说明：本技术 一种音叉型结构的压电致动器及其工作方法 (Piezoelectric actuator with tuning fork type structure and working method thereof ) 是由 纪华伟 纪涵 吕博 任栩斌 于 2021-07-27 设计创作，主要内容包括：本发明公开了一种音叉型结构的压电致动器及其工作方法,本发明压电致动器包括基板、定子、动子,所述的定子包括金属弹性体,金属弹性体安装于所述的基板,金属弹性体设有对称的悬臂梁,悬臂梁呈弧形,朝向对侧；金属弹性体的两表面以及悬臂梁的两表面各粘接压电陶瓷片；所述的动子直线滑动式地装配于所述的基板,所述的动子包括滑动片；所述定子的两悬臂梁能夹持所述的滑动片并促使滑动片作步进运动。本发明基于传统的贴片式压电致动器结构设计,研发了一种高精度、低噪音、结构小巧的压电致动器。(The invention discloses a piezoelectric actuator with a tuning fork type structure and a working method thereof, the piezoelectric actuator comprises a substrate, a stator and a rotor, wherein the stator comprises a metal elastic body which is arranged on the substrate, the metal elastic body is provided with symmetrical cantilever beams, and the cantilever beams are arc-shaped and face to the opposite side; the two surfaces of the metal elastic body and the two surfaces of the cantilever beam are respectively bonded with piezoelectric ceramic pieces; the mover is linearly and slidably assembled on the substrate, and comprises a sliding sheet; the two cantilever beams of the stator can clamp the sliding sheet and promote the sliding sheet to move in a stepping mode. The invention develops a piezoelectric actuator with high precision, low noise and small structure based on the structural design of the traditional patch type piezoelectric actuator.)

1. A piezoelectric actuator with a tuning fork type structure is characterized by comprising a base plate, a stator and a rotor, wherein the stator comprises a metal elastic body which is arranged on the base plate, the metal elastic body is provided with symmetrical cantilever beams, and the cantilever beams are arc-shaped and face to the opposite side; piezoelectric ceramic plates are respectively bonded on two surfaces of the metal elastic body and two surfaces of the cantilever beam; the mover is linearly and slidably assembled on the substrate, and comprises a sliding sheet; the two cantilever beams of the stator can clamp the sliding sheet and promote the sliding sheet to move in a stepping mode.

2. A piezoelectric actuator of a tuning-fork type structure according to claim 1, wherein: and arranging a pre-tightening base, wherein the pre-tightening base is used for installing the substrate.

3. A piezoelectric actuator of a tuning-fork type structure according to claim 2, wherein: the pretension base is provided with a linear guide rail which is in sliding fit with the rotor.

4. A piezoelectric actuator of a tuning-fork type structure according to claim 3, wherein: the rotor comprises a sliding block, the sliding block is in sliding fit with the linear guide rail, and the sliding block is attached to and fixedly connected with the sliding sheet.

5. Piezoelectric actuator of tuning-fork type construction according to any of claims 1-4, characterized in that: the sliding sheet is convex, the convex part of the sliding sheet is matched with the cantilever beams at the two sides of the stator, and the two cantilever beams of the stator can clamp the convex part of the sliding sheet.

6. A piezoelectric actuator of a tuning-fork type structure according to any one of claims 2 to 4, wherein: the section of the pre-tightening base is concave, and two pre-tightening bolts are respectively screwed on two side walls.

7. Piezoelectric actuator of tuning-fork type construction according to any of claims 1-4, characterized in that: the base plate is in a one-level step shape, the stator is installed on the high step surface, and the rotor is installed on the low step surface.

8. Piezoelectric actuator of tuning-fork type construction according to any of claims 1-4, characterized in that: the metal elastic body and the piezoelectric ceramic piece are bonded by epoxy resin.

9. Piezoelectric actuator of tuning-fork type construction according to any of claims 1-4, characterized in that: the metal elastic sheet is made of beryllium bronze.

10. A method of operating a piezoelectric actuator of a tuning fork type construction as claimed in any one of claims 1-9, characterized by the steps of:

the method comprises the following steps that firstly, polarization treatment in opposite directions is carried out on piezoelectric ceramic pieces which are stuck to the front surface and the back surface of a metal elastic piece and the cantilever beam;

applying alternating voltage sin (ω t) with stable rated frequency to the piezoelectric ceramic sheet adhered to the body part of the metal elastic sheet to excite the bending vibration mode of the body part of the metal elastic sheet and drive the cantilever beam to perform clamping action, so that sufficient friction force is generated between the cantilever beam of the stator and the rotor;

step three, applying the piezoelectric ceramic piece adhered to the cantilever beamThe electric field excitation signal excites the longitudinal vibration of the cantilever beam to drive the rotor to move forwards linearly.

Technical Field

The invention belongs to the technical field of ultrasonic motor manufacturing, and particularly relates to a piezoelectric actuator with a tuning fork type structure and a working method thereof, which can realize precise driving and positioning functions.

Background

With the progress and development of science and technology, especially the rapid development of the technical fields of aerospace, biomedicine, precise electronic instruments and the like, the world puts higher-level requirements on novel micro-actuators, such as miniaturization, light weight, no electromagnetic interference and the like. The conventional motor and gas valve are limited by their structures, so that it is difficult to reduce the size of the device, and the conventional motor and gas valve generate noise during operation, resulting in inconvenience and discomfort in use. Therefore, the piezoelectric actuator is distinguished in various novel micro-actuators due to the advantages of high response speed, large output force, compact structure, strong interference resistance and the like. In the conventional piezoelectric actuator, a piezo stack type and a sandwich type structure design are adopted, and the application scenarios of the conventional piezoelectric actuator are limited due to the large thickness of the conventional piezoelectric actuator. Compared with the traditional piezoelectric actuator, the patch type piezoelectric actuator stator structure is simpler in assembly, small in longitudinal size and simple and convenient in signal excitation, and is more suitable for the miniaturization development of the piezoelectric actuator.

The traditional patch type piezoelectric actuator has the working mechanism that the inverse piezoelectric effect of piezoelectric ceramics is utilized to excite the high-frequency micro-amplitude motion of a metal elastic body stator, the elliptic motion track of the head of the stator is realized, and the vibration is converted into the displacement output of a rotor through the stick-slip friction action between the stator and the rotor to drive a load. However, the existing piezoelectric actuator has the problems of low precision, high noise, large structure and complexity.

Disclosure of Invention

In order to solve the problems in the prior art, the invention discloses a piezoelectric actuator with a tuning fork type structure and a working method thereof. The invention designs and develops a tuning fork type piezoelectric actuator based on stick-slip driving on the basis of the mechanical structure and performance output of the existing patch type piezoelectric actuator. Excellent experimental parameters are obtained by carrying out dynamics theory modeling, simulation optimization and experimental research on a model of the piezoelectric actuator, so that the good output performance of the piezoelectric actuator is ensured.

In order to solve the problems, the invention adopts the following technical scheme:

a piezoelectric actuator with a tuning fork type structure comprises a substrate, a stator and a rotor, wherein the stator comprises a metal elastic body, the metal elastic body is arranged on the substrate, symmetrical cantilever beams are arranged on the metal elastic body, and the cantilever beams are arc-shaped and face to the opposite side; piezoelectric ceramic plates are respectively bonded on two surfaces of the metal elastic body and two surfaces of the cantilever beam; the mover is linearly and slidably assembled on the substrate, and comprises a sliding sheet; the two cantilever beams of the stator can clamp the sliding sheet and promote the sliding sheet to move in a stepping mode.

Preferably, a pre-tightening base is arranged, and the pre-tightening base is used for mounting the substrate.

Preferably, the pretension base is provided with a linear guide rail, and the linear guide rail is in sliding fit with the rotor.

Preferably, the rotor comprises a sliding block, the sliding block is in sliding fit with the linear guide rail, and the sliding block is attached and fixedly connected with the sliding sheet.

Preferably, the sliding sheet is convex, the convex part of the sliding sheet is matched with the cantilever beams at two sides of the stator, and the two cantilever beams of the stator can clamp the convex part of the sliding sheet.

Preferably, the section of the pre-tightening base is concave, and two pre-tightening bolts are screwed on two side walls respectively.

Preferably, the base plate is in a one-stage step shape, the stator is installed on the high step surface, and the mover is installed on the low step surface.

Preferably, the metal elastic body and the piezoelectric ceramic plate are bonded by epoxy resin.

Preferably, the metal elastic sheet is made of beryllium bronze.

The working method of the piezoelectric actuator with the tuning fork type structure comprises the following steps:

the method comprises the following steps that firstly, polarization treatment in opposite directions is carried out on piezoelectric ceramic pieces which are stuck to the front surface and the back surface of a metal elastic piece and the cantilever beam;

applying alternating voltage sin (ω t) with stable rated frequency to the piezoelectric ceramic sheet adhered to the body part of the metal elastic sheet to excite the bending vibration mode of the body part of the metal elastic sheet and drive the cantilever beam to perform clamping action, so that sufficient friction force is generated between the cantilever beam of the stator and the rotor;

step three, piezoelectric ceramics pasted on the cantilever beamSheet applicationThe electric field excitation signal excites the longitudinal vibration of the cantilever beam to drive the rotor to move forwards linearly.

The principle of the stator driving rotor of the piezoelectric actuator with the tuning fork type structure is the application of the stick-slip effect, the driving mode based on the stick-slip effect is a periodic motion mode with alternating dynamic and static friction, and meanwhile, due to the bending vibration of the piezoelectric laminated plate, the motion track of the stator is elliptical, and the phase difference of voltage is changed to change the motion track of the stator, so that the maximum operation speed of the piezoelectric actuator under the designed load is realized. In addition, the stator stepping period is close to and far away from the rotor under the elliptic motion trail, so that stick-slip alternative motion is realized, the sliding table rotor is driven to rapidly step, and the conversion from electric energy to mechanical energy is completed.

On the basis of the structural design of the traditional patch type piezoelectric actuator, the invention develops the piezoelectric actuator with high precision, low noise and small structure. The piezoelectric actuator can be suitable for increasing the stability of the mobile phone camera in a special extreme scene, is beneficial to reducing the energy consumption of the mobile phone and increasing the endurance time of the mobile phone.

Drawings

FIG. 1 is an overall assembly view of the piezoelectric actuator of the present invention;

FIG. 2 is a top view of the piezoelectric actuator of the present invention;

FIG. 3 is a right side view of the piezoelectric actuator of the present invention;

FIG. 4 is a stator structural view of a tuning fork type structure piezoelectric actuator;

FIG. 5 is a stator bending mode diagram of an electrically excited lower piezoelectric actuator;

fig. 6 is an equivalent circuit diagram of the piezoelectric composite beam.

In the figure, 1 is a linear guide rail; 2 is a slide block; 3 is a sliding sheet; 4 is a pre-tightening base; 5, a pre-tightening bolt; 6 is a piezoelectric ceramic piece; 7 is a fixing bolt; 8 is a metal elastic sheet; 9 is a substrate; 10 is a pre-tightening bolt; 11 is a rotor; and 12 is a stator.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to the accompanying drawings.

As shown in fig. 1-3, the piezoelectric actuator of this embodiment includes a pre-tightening base 4, a stator 12, a substrate 9, a mover 11 and a linear guide 1, the cross section of the pre-tightening base 4 is concave, two side walls of the pre-tightening base are respectively screwed with pre-tightening bolts 5 and 10, the pre-tightening bolts are fixed on two sides of the tuning fork, and apply pre-tightening forces symmetrical in the large and small directions to the tuning fork; the early warning bolt is inserted through the limiting hole of the early warning base, can be screwed freely and can compress two sides of the stator. A substrate 9 is mounted in a concave portion of the pre-tightening base 4, and the substrate 9 is stepped.

The stator 12 includes a metal elastic sheet 8 and a piezoelectric ceramic sheet 6, the piezoelectric ceramic sheet is a rectangular structure and is made of lead zirconate titanate material, the side length of the piezoelectric ceramic sheet is not larger than that of the metal elastic sheet 8, and the piezoelectric ceramic sheet is used for applying voltage to drive the metal elastic sheet to perform bending vibration. The metal elastic sheet 8 may be made of beryllium copper, and is mounted on the high step surface of the substrate 9 by two fixing bolts 7. The upper surface and the lower surface of the metal elastic sheet 8 are respectively stuck with a piezoelectric ceramic sheet 6. The metal elastic body and the piezoelectric ceramic piece are bonded by epoxy resin.

Symmetrical cantilever beams are formed at the front parts of the two sides of the metal elastic sheet 8, and the cantilever beams are arc-shaped and face the opposite side. The upper and lower surfaces of the cantilever beams at two sides are respectively pasted with a piezoelectric ceramic piece, and the piezoelectric ceramic pieces at the positions are not connected with the piezoelectric ceramic pieces at the front. Fig. 4 is a schematic structural diagram of the tuning-fork stator 12 of the present invention, wherein the upper and lower surface areas of the stator are the patch positions of the piezoelectric ceramic plates 6; d is the stator thickness; b is₀Is the width of the rear end of the stator, B₁For the width of the fixed end of the cantilever beam, the included angle alpha between the outer sides of the sound fork is 2 (pi-theta), the range of the included angle theta is set to be 150-180 degrees, and the value range of the included angle alpha is 0-60 degrees.

The linear guide rail 1 is installed along the length direction of the middle part on the low step surface of the base plate 9, the mover 11 is assembled on the linear guide rail, and the mover 11 comprises a sliding block 2 and a sliding sheet 3. Linear guide 1 sliding fit slider 2, slider 2's upper surface laminating and through four fixing bolt installation sliders 3, slider 3 is the convex, and the slider convex part is roughly the same with metal elastomer both sides location, and its convex part and stator 12's both sides cantilever beam looks adaptation action, the convex part of both sides cantilever beam ability centre gripping slider 3. The stator 12 provided with the piezoelectric ceramics 6 is applied with an excitation voltage to generate piezoelectric ceramics characteristics, so that the mover 11 composed of the slider 2 and the slider 3 is driven to move in rapid steps.

The tuning fork type piezoelectric actuator stator can be regarded as a double-electric-layer structure, applies excitation voltage to the surface of piezoelectric ceramic to excite the inverse piezoelectric effect of the piezoelectric ceramic, and utilizes d₃₁Effect (d)₃₁The effect belongs to one of piezoelectric effects, namely the direction of force generated by piezoelectric ceramics is vertical to the polarization direction of the piezoelectric ceramics) to drive the metal elastic body to stretch and contract to complete an elliptic motion track, so that the sliding table rotor is driven to rapidly move step by step to complete conversion from electric energy to mechanical energy. FIG. 5 shows the bending vibration mode of the tuning fork body in the electrically excited mode. Sin (ω t) electric field excitation signals are applied to the surfaces of the two piezoelectric ceramic plates of the body part, the bending vibration mode of the body part is mainly excited, and the tuning fork is driven to do clamping motion, so that sufficient friction force is generated between the tuning fork head of the stator and the rotor. At the same time, four piezoceramic wafer surface applications at the tuning fork endAnd an electric field excitation signal mainly excites the longitudinal vibration of the front-end stator tuning fork part and drives the stator to move forwards linearly under the state of clamping the stator.The phase difference of the two-phase voltage is the metal elastic body grounding wire. The frequency of the alternating voltage applied to the piezoelectric ceramic is 1-50 Hz, and the amplitude of the alternating voltage applied to the piezoelectric ceramic is set to be 10-50V. Under the condition that the phase difference and the excitation signal are reasonable, the elliptical motion of the stator at the driving foot (the driving foot is the place where the top of the tuning fork is contacted with the mover) can be excited (also called deformation, namely, the deformation causes the stator to generate an elliptical motion track).

FIG. 6 is an equivalent circuit diagram of a piezoelectric composite beam, in which piezoelectric ceramics are equivalent to a capacitor, and the piezoelectric composite beam can be equivalent to two electrodesContainer C₀、C₁After being connected in parallel, the piezoelectric sheet is connected with the equivalent resistance R of the metal elastomer in series, and the resistance R exists in the piezoelectric sheet₁The piezoelectric ceramic can be ideally equivalent to an element with a capacitor and a resistor connected in parallel. According to the charge-discharge principle of the capacitor, the actual voltage U is applied to two ends of the piezoelectric beam₁The following formula

Wherein, U₀Output voltage of power supply for driving piezoelectric actuator, U₁Is the actual voltage across the piezoelectric ceramic, C₀The equivalent capacitance value of the piezoelectric ceramic piece is shown, and R is the equivalent resistance of the metal elastic body. Because the piezoelectric ceramic piece has the self resistance R₁R, the sum of the above formula and Δ l ═ u (t) d₃₁Combining and obtaining the elongation delta l of the piezoelectric sheet in the length direction and the output voltage U of the driving power supply after Laplace conversion₀The relationship function of (1) is:

as shown in fig. 5, the present invention also discloses a working method of a piezoelectric actuator with a tuning fork structure, comprising the following steps:

polarizing the piezoelectric ceramic plates 6 adhered to the tuning-fork piezoelectric actuator stator 12, wherein the piezoelectric ceramic plates 6 are adhered to the front and back surfaces of the stator 12, so that the piezoelectric ceramic plates 6 on the front and back surfaces are polarized in opposite directions;

applying alternating voltage sin (ω t) with stable rated frequency to the piezoelectric ceramic sheet 6 adhered to the body part of the stator 12 to excite the bending vibration mode of the body part of the stator 12, and driving the tuning fork to clamp, so that sufficient friction force is generated between the tuning fork head of the stator 12 and the mover 11;

step three, applying the piezoelectric ceramic plate 6 surface at the tuning fork endThe electric field excitation signal mainly excites the longitudinal vibration of the front stator tuning fork part, drives the stator 12 to move forwards in a straight line under the state of clamping the rotor 11,the phase difference of the two-phase voltage is the metal elastic body grounding wire. In the case of a reasonable phase difference and excitation signal, an elliptical movement of the stator at the drive foot can be excited, so that the rotor 11 slides.

The piezoelectric actuator with the tuning fork type structure comprises a stator, a substrate, a linear guide rail, a pre-tightening bolt, a sliding block and the like, wherein the stator is formed by sticking piezoelectric ceramics on two sides of the surface of a metal elastomer, and is clamped on one side of the substrate through a fixing bolt; the linear guide rail is fixed on the base plate, and the sliding block and the sliding sheet jointly form a sliding table rotor which is driven by the stator; in the clamping process, the actuator is fixed by using bolts at two sides of the end part of the stator, and the end part of the tuning fork of the stator adopts a free cantilever beam structure; in the application mode of the pre-pressure, the pre-tightening bolts are simultaneously rotated on two sides of the tuning fork by the actuator, so that the pre-pressure is symmetrical in the size direction, and the positioning accuracy of the small linear actuator is improved.

The piezoelectric actuator can be used for focusing the lens in the camera of the mobile phone, and has large power consumption because the traditional lens is focused by the stepping motor, but the power consumption is greatly reduced after the piezoelectric actuator is driven by the piezoelectric actuator, and the change amplitude of the performance of the piezoelectric actuator is smaller at extreme temperature.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.