CN118017869A - Multi-mode driving piezoelectric thread motor and excitation method thereof - Google Patents

Abstract

The invention discloses a multi-mode driving piezoelectric thread motor and an excitation method thereof, and relates to the technical field of precise driving and positioning. The invention comprises a stator plate and a cover plate which are distributed up and down; the stator plate is connected with four piezoelectric drivers and four flexible hinges, a moving part is connected through the four flexible hinges, the moving part is provided with a threaded hole, the moving part is connected with a screw rod in a threaded manner, the cover plate is movably inserted with an output shaft, and one end of the output shaft abuts against the end part of the screw rod; four piezoelectric drivers and four flexible hinges all set up along screw hole circumference equipartition, and the length direction of piezoelectric drivers respectively with screw hole tangential direction parallel arrangement for drive motion portion along screw hole tangential direction through flexible hinge. According to the invention, the four piezoelectric drivers drive the moving part along the tangential direction of the threaded hole through the flexible hinge, and different excitation signals are applied, so that the problem that the existing piezoelectric motor cannot simultaneously give consideration to high speed and high resolution, and has poor adaptability is solved.

Description

Multi-mode driving piezoelectric thread motor and excitation method thereof

Technical Field

The invention belongs to the technical field of precise driving and positioning, and particularly relates to a multi-mode driving piezoelectric thread motor and an excitation method thereof.

Background

Piezoelectric motors are widely used in fields requiring precise control, such as biomedicine, precise instruments, aerospace, and the like, due to the advantages of high precision, high resolution, vacuum compatibility, and the like. The piezoelectric motor is more particularly applied to precise adjustment of the position of a lens in a microscope, control of the position and the posture of a control wafer in semiconductor manufacturing, precise drug delivery and the like.

Piezoelectric motors are classified into static, quasi-static and resonant modes according to the operating frequency. The piezoelectric motor is driven by direct current during static operation. This state is used to achieve displacement compensation and high precision micro-positioning due to the small output displacement of the piezoelectric stack. Quasi-static piezoelectric motors include inchworm-type piezoelectric and impact-type piezoelectric motors, which typically excite the stator by non-sinusoidal periodic waves, and which have low output displacement and frequency, and thus have the characteristics of low speed and high resolution. Resonant mode piezoelectric motors are typically excited into resonance and excite a particular mode by applying a sine wave excitation to the stator. The vibration amplitude of the object is increased due to the enhancement of energy transfer efficiency at resonance, and the piezoelectric motor in a resonance state can generally realize high-speed motion, but has relatively low resolution.

Most piezoelectric motors currently operate in one of a static, quasi-static and resonant state. For example, chinese patent CN103929090B discloses a rotary linear ultrasonic motor with a cylinder structure excited by a piezoelectric driver and an excitation method thereof, wherein the ultrasonic motor works in a resonance state, is excited by an alternating current signal with a phase difference of 90 ° to excite a bending mode of a nut, and generates a driving force through screw pair transmission. Chinese patent CN110336485A discloses a piezoelectric impact driven two-dimensional parallel cross-scale precision positioning platform, where the piezoelectric driver works in quasi-static state, and generates high precision stepping motion of the motor by saw tooth wave excitation.

However, the development of the field of precision control is increasingly required to make the piezoelectric motor compatible with high speed and high resolution, but the piezoelectric motor in the prior art cannot simultaneously compatible with high speed and high resolution, resulting in poor overall adaptability.

Disclosure of Invention

The invention aims to provide a multi-mode driving piezoelectric thread motor and an excitation method thereof, wherein four piezoelectric drivers drive a moving part along the tangential direction of a threaded hole through flexible hinges, and different excitation signals are applied, so that the problem that the existing piezoelectric motor cannot simultaneously give consideration to high speed and high resolution, and has poor adaptability is solved.

In order to solve the technical problems, the invention is realized by the following technical scheme:

The invention relates to a multi-mode driving piezoelectric thread motor, which comprises a stator plate and a cover plate which are distributed up and down; the stator plate is connected with four piezoelectric drivers and four flexible hinges, a moving part is connected through the four flexible hinges, the moving part is provided with a threaded hole and is in threaded connection with a screw rod, the cover plate is movably inserted with an output shaft, and one end of the output shaft abuts against the end part of the screw rod; the four piezoelectric drivers and the four flexible hinges are uniformly distributed along the circumference of the threaded hole, the positions of the four piezoelectric drivers and the flexible hinges are offset from the center line of the appearance of the stator plate to a certain extent, so that the motor can simultaneously realize torsion movement of the moving part by utilizing the expansion and contraction of the piezoelectric stack in static state and quasi-static state, elliptical movement of the moving part is generated in resonance state, and specifically, the length directions of the piezoelectric drivers are respectively arranged in parallel with the tangential direction of the threaded hole and are used for driving the moving part along the tangential direction of the threaded hole through the flexible hinges.

As a preferable technical scheme of the invention, the stator plate, the flexible hinge and the moving part are of an integrated structure; wherein, the stator board has seted up the mounting groove that links to each other with flexible hinge one by one for install piezoelectric actuator through the mounting groove.

As a preferable technical scheme of the invention, two ends of the piezoelectric driver are provided with insulating gaskets.

As a preferable technical scheme of the invention, the side surface of the stator plate is provided with threaded through holes which are communicated with the mounting grooves one by one, and is in threaded connection with a set screw, and the set screw is used for extruding the end part of the piezoelectric driver through the end part of the set screw so as to realize the adjustment of the pre-pressure of the piezoelectric driver.

As a preferable technical scheme of the invention, the set screw is in threaded fit with a locking nut for locking the set screw.

As a preferable technical scheme of the invention, the end part of the screw is provided with a curved surface structure, and the curved surface structure is used for realizing point contact with the end surface of the output shaft.

As a preferable technical scheme of the invention, the end face of the screw is provided with the caulking groove, and the ball is fixedly connected with the caulking groove and used for realizing point contact with the end face of the output shaft through the ball.

As a preferable technical scheme of the invention, the centers of the screw holes of the four piezoelectric drivers are symmetrically arranged in pairs, and the wiring of the two opposite piezoelectric drivers is opposite.

The excitation method for driving the piezoelectric thread motor in a multi-mode comprises the following steps:

In a static mode, the same direct current is applied to the four piezoelectric drivers, so that high-precision micro-positioning of the piezoelectric thread motor is realized;

In a quasi-static mode, the same sawtooth wave excitation signals are applied to the four piezoelectric drivers, so that low-frequency and high-precision movement of the piezoelectric thread motor is realized.

As a preferable technical scheme of the invention, the high-speed motion of the piezoelectric thread motor is realized by applying sine wave excitation signals to two opposite piezoelectric drivers and sine wave excitation signals with 90-degree phase difference to the other two opposite piezoelectric drivers in a resonance mode.

The invention has the following beneficial effects:

According to the invention, four piezoelectric drivers are arranged on the stator plate, the flexible hinge drives the moving part along the tangential direction of the threaded hole, and the screw rod connected with the threaded hole is slightly twisted under the action of friction force by using the torsion of the driving part, so that the high-precision positioning is realized.

And by inputting different excitation signals and changing the amplitude, phase and duty ratio of the excitation signals, the motion direction and speed of the piezoelectric driver are regulated, so that the piezoelectric thread motor is switched between high-speed motion and high-resolution motion, the electric thread motor can meet high-speed and high-resolution driving, and the overall adaptability is effectively improved.

Of course, it is not necessary for any one product to practice the invention to achieve all of the advantages set forth above at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a multi-mode drive piezoelectric screw motor according to the present invention;

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a schematic structural view of a stator plate;

FIG. 4 is a top view of FIG. 3;

FIG. 5 is a schematic view of the structure of the moving part in the static mode;

FIG. 6 is a schematic diagram of excitation signals operating in quasi-static mode;

FIG. 7 is a schematic diagram of the structure of the torsion of the moving part in the quasi-static mode;

FIG. 8 is a wiring diagram of a resonant mode piezoelectric actuator;

FIG. 9 is a schematic diagram of excitation signals operating in a resonant mode;

FIG. 10 is a schematic diagram of a moving part at the moment of mode 0 in the resonant state;

FIG. 11 is a schematic diagram of a moving part at a time of a resonant mode t 1;

Fig. 12 is a schematic diagram of a moving part at a time t2 of a resonance mode;

Fig. 13 is a schematic diagram of a moving part at a time t3 of a resonance mode;

in the drawings, the list of components represented by the various numbers is as follows:

the device comprises a 1-stator plate, a 2-cover plate, a 3-piezoelectric driver, a 4-screw rod, a 5-output shaft, a 7-set screw, a 101-flexible hinge, a 102-moving part, a 103-threaded hole, a 301-insulating gasket, a 401-sphere and a 701-locking nut.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be understood that the terms "open," "upper," "lower," "thickness," "top," "middle," "length," "inner," "peripheral," and the like indicate orientation or positional relationships, merely for convenience in describing the present invention and to simplify the description, and do not indicate or imply that the components or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

Example 1

Referring to fig. 1, the invention relates to a multi-mode driving piezoelectric thread motor, which comprises a stator plate 1 and a cover plate 2 which are distributed up and down, wherein the cover plate 2 is fixedly connected above the stator plate 1 through hexagonal copper columns, and the stator plate 1 is arranged on a base through the hexagonal copper columns.

The stator plate 1 is connected with four piezoelectric drivers 3 and four flexible hinges 101, and is connected with a moving part 102 through the four flexible hinges 101, and the moving part 102 is provided with a threaded hole 103 and is in threaded connection with a screw 4. Wherein the stiffness of the flexible hinge 101 should be much smaller than the stiffness of the piezoelectric stack to ensure that the displacement of the piezoelectric stack can be transferred effectively.

As shown in fig. 2, the cover plate 2 is movably inserted with an output shaft 5 through a linear bearing, the output shaft 5 is in a stepped shaft structure, and the lower end of the output shaft 5 abuts against the end part of the screw 4. The end of the screw 4 is provided with a curved surface structure 401 for realizing point contact with the end surface of the output shaft 5 through the curved surface structure, thereby reducing friction between the screw 4 and the output shaft 5 and converting rotary motion of the screw 4 into linear motion of the output shaft 5.

The end face of the screw 4 is provided with a caulking groove, the ball 401 is fixedly connected with the caulking groove through the caulking groove, and the ball 401 and the caulking groove can be fixedly connected through interference fit and are used for realizing point contact with the end face of the output shaft 5 through the ball 401.

As shown in fig. 3 and 4, four piezoelectric drivers 3 and four flexible hinges 101 are uniformly distributed along the circumference of the threaded hole 103, and the length directions of the piezoelectric drivers 3 are respectively parallel to the tangential direction of the threaded hole 103, the piezoelectric drivers 3 are piezoelectric stacks, when an excitation signal is applied to the piezoelectric drivers 3, the piezoelectric drivers 3 stretch or shrink, and drive the flexible hinges 101 to drive the moving part 102 along the tangential direction of the threaded hole 103 through the flexible hinges 101, so that the moving part 102 is twisted.

Specifically, the stator plate 10, the flexible hinge 101, and the moving part 102 are of an integral structure; wherein, the stator plate 10 is provided with mounting grooves which are connected with the flexible hinges 101 one by one and used for mounting the piezoelectric drivers 3 through the mounting grooves, and one ends of the piezoelectric drivers 3 are propped against the flexible hinges 101.

Meanwhile, the insulating spacers 301 are installed at both ends of the piezoelectric driver 3, so that the electric signal applied to the piezoelectric driver 3 can be prevented from being directly communicated with the stator plate 1, resulting in an electric shock to a user in use, and thus the safety can be advantageously improved by installing the insulating spacers 301.

And, the threaded through holes communicated with the mounting grooves one by one are formed in the side face of the stator plate 10, the fastening screws 7 are connected with threads, and are used for extruding the end parts of the piezoelectric drivers 3 through the end parts of the fastening screws 7, so that the pre-compression force of the piezoelectric drivers 3 is adjusted, the end parts of the piezoelectric drivers 3 are tightly attached to the flexible hinges 101, and the insulating gaskets 301 can also prevent the situation that the torque of the fastening screws 7 damages the piezoelectric stacks when the fastening screws 7 are used for adjusting the pre-compression force of the piezoelectric stacks. The fastening screw 7 is in threaded fit with a locking nut 701 for locking the fastening screw 7, so that the fastening screw 7 is prevented from loosening due to high-frequency vibration when the piezoelectric driver 3 is in operation.

Example two

An excitation method for a multi-mode driving piezoelectric thread motor, comprising:

as shown in fig. 5, in the static mode, the same direct current is applied to the four piezoelectric drivers 3, the piezoelectric drivers 3 are stretched and kept at a certain length, the flexible hinge 101 drives the moving part 102 to perform torsion movement, the screw 4 is also twisted under the action of static friction force, the maximum output displacement of the piezoelectric stack is in the micrometer level or even in the submicron level, the screw 4 performs tiny movement under the action of friction force, and therefore, the high-precision micro-positioning of the piezoelectric screw motor can be realized by utilizing the state, and the resolution of the piezoelectric screw motor in the static mode can reach 0.5nm.

Quasi-static mode by applying the same saw-tooth excitation signal to the four piezo-electric drivers 3. Wherein the excitation frequency of the sawtooth wave is much smaller than the first order resonance frequency of the stator plate 1 to prevent the stator plate 1 from resonating.

As shown in fig. 6 and 7, at time t0, the voltage of the sawtooth wave is 0, and the four piezoelectric drivers 3 are all held in the initial state, so the moving portion 102 is held in the initial state as shown in fig. 4.

In the period from t0 to t1, the voltage of the sawtooth wave gradually increases from 0 to Um, and therefore, the four piezoelectric actuators 3 slowly extend, and as shown in fig. 7, the moving part 102 turns by a torsion angle θ with respect to the initial state, and the screw 4 rotates by the θ angle similarly by the static friction force.

In the period from t1 to t2, the voltage of the sawtooth wave drops rapidly from Um to 0, so that the piezoelectric driver 3 also shortens rapidly, the moving part 102 returns to the initial state, the screw 4 remains stationary or withdraws θ 'under the action of inertia, and θ' is smaller than θ, and the screw 4 rotates by a slight angle relative to the initial state.

Under periodic saw-tooth wave, the piezoelectric driver 3 drives the moving part 102 in the center of the stator plate 1 to make impact motion. Because the displacement of the piezoelectric stack is in the micron level or even in the submicron level in one period of impact motion, the piezoelectric thread motor in the quasi-static mode can provide high-precision motion, but the speed is lower, and the motion speed and the motion direction of the piezoelectric thread motor can be adjusted by changing the duty ratio of the sawtooth wave.

In a quasi-static mode, the piezoelectric thread motor is excited by a sawtooth wave with the frequency of 1000Hz, the displacement resolution of the piezoelectric thread motor is 0.93nm at 42V _PP, the speed reaches 19.58 mu m/s at 400V _PP, and the load reaches 650g.

Example III

As shown in fig. 8, the four piezoelectric drivers 3 are symmetrically arranged in the center of the two opposite screw holes 103, and the two opposite piezoelectric drivers 3 are connected in opposite directions, and the four piezoelectric drivers 3 are sequentially a first piezoelectric stack 31, a second piezoelectric stack 32, a third piezoelectric stack 33 and a fourth piezoelectric stack 34 along the circumferential direction of the screw holes 103. The first piezoelectric stack 31 is paired with the third piezoelectric stack 33, and the second piezoelectric stack 32 is paired with the fourth piezoelectric stack 34, and the mutual indirect lines are opposite.

As shown in fig. 9, the piezoelectric thread motor further includes a resonant mode, and a stator plate specific mode is excited by applying a set of sine wave excitation signals to two opposite piezoelectric drivers 3 and applying sine wave excitation signals which are 90 ° out of phase with the first set of excitation signals to the other two opposite piezoelectric drivers 3, so that high-speed movement of the piezoelectric thread motor is realized.

If a voltage Ux is applied to the first piezo-stack 31 and the third piezo-stack 33, a voltage Uy is applied to the second piezo-stack 32 and the fourth piezo-stack 34, wherein the phase difference of Uy and Ux is 90 °. The frequency of the excitation voltage is the first order flexural vibration frequency of the flexible hinge 101.

As shown in fig. 10, at time 0, the first piezoelectric stack 31 and the third piezoelectric stack 33 are kept in the initial state due to the applied voltage of 0. The second piezoelectric stack 32 and the fourth piezoelectric stack 34 are subjected to the voltage Um, the second piezoelectric stack 32 is elongated, the fourth piezoelectric stack 34 is shortened, and the moving portion 1102 is located at the top of the moving track.

As shown in fig. 11, in the period of 0 to t1, the voltages applied to the first piezoelectric stack 31 and the third piezoelectric stack 33 are increased from 0 to Um, the first piezoelectric stack 31 is extended, the third piezoelectric stack 33 is shortened, the voltages applied to the second piezoelectric stack 32 and the fourth piezoelectric stack 34 are decreased from Um to 0, the second piezoelectric stack 32 is shortened to 0, the fourth piezoelectric stack 34 is extended to 0, and the movement portion 102 moves clockwise toward the right side of the movement locus.

As shown in fig. 12, in the period t1 to t2, the voltage applied to the first piezoelectric stack 31 and the third piezoelectric stack 33 decreases from Um to 0, the first piezoelectric stack 31 shortens to 0, and the third piezoelectric stack 33 extends to 0. The voltage applied to the second piezoelectric stack 32 and the fourth piezoelectric stack 34 decreases from 0 to-Um, the second piezoelectric stack 32 shortens, the fourth piezoelectric stack 34 lengthens, and the moving portion 102 moves clockwise toward the bottom of the movement trace.

As shown in fig. 13, in the period of t2 to t3, the voltages applied to the first piezoelectric stack 31 and the third piezoelectric stack 33 decrease from 0 to-Um, the first piezoelectric stack 31 shortens, the third piezoelectric stack 33 extends, the voltages applied to the second piezoelectric stack 32 and the fourth piezoelectric stack 34 increase from-Um to 0, the second piezoelectric stack 32 extends to the original length, the fourth piezoelectric stack 34 shortens to the original length, and the movement portion 102 moves clockwise toward the left side of the movement locus.

As shown in fig. 10, in the period t3 to t4, the voltages applied to the first piezoelectric stack 31 and the third piezoelectric stack 33 are increased from-Um to 0, the first piezoelectric stack 31 is extended to the original length, the third piezoelectric stack 33 is shortened to the original length, the voltages applied to the second piezoelectric stack 32 and the fourth piezoelectric stack 34 are increased from 0 to Um, the second piezoelectric stack 32 is extended, the fourth piezoelectric stack 34 is shortened, and the moving portion 102 moves clockwise toward the top of the movement locus.

The piezoelectric screw motor moves in one period in the resonance mode, and the piezoelectric driver 3 and the moving part 102 resonate and are excited to a specific mode under the excitation of a periodic sine wave signal, so that the moving part 102 realizes elliptical motion in the mode, and the screw 4 moves under the action of friction force.

The phase difference 90 degrees of sine wave excitation signals are adjusted to be-90 degrees, and the reverse motion of the piezoelectric thread motor can be realized. Because the energy transfer efficiency is enhanced during resonance, the vibration amplitude of the object is increased, so that the amplitude of the flexible hinge 101 in a resonance state is far greater than that in a quasi-static mode, and the piezoelectric thread motor in the resonance state can realize high-speed motion, but the resolution is low relative to that in the quasi-static state. Specifically, the piezoelectric thread motor is in a resonance state mode, the frequency is 10400Hz, the speed of the piezoelectric thread motor reaches 8.5mm/s under 150V _PP sine waves, and the load is 3600g.

In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended only to assist in the explanation of the invention. The preferred embodiments are not exhaustive or to limit the invention to the precise form disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best understand and utilize the invention. The invention is limited only by the claims and the full scope and equivalents thereof.

Claims (10)

1. A multi-mode driving piezoelectric thread motor comprises a stator plate (1) and a cover plate (2) which are distributed up and down; the stator board (1) is connected with four piezoelectric drivers (3) and four flexible hinges (101) and is connected with a moving part (102) through the four flexible hinges (101), and the moving part (102) is provided with a threaded hole (103) and is in threaded connection with a screw rod (4), and is characterized in that:

An output shaft (5) is movably inserted in the cover plate (2), and one end of the output shaft (5) is propped against the end part of the screw rod (4); four piezoelectric drivers (3) and four flexible hinges (101) are uniformly distributed along the circumference of the threaded hole (103), and the length directions of the piezoelectric drivers (3) are respectively arranged in parallel with the tangential direction of the threaded hole (103) and used for driving the moving part (102) along the tangential direction of the threaded hole (103) through the flexible hinges (101).

2. A multi-mode driving piezoelectric thread motor according to claim 1, wherein the stator plate (10), the flexible hinge (101) and the moving part (102) are of an integral structure; wherein, stator board (10) has seted up the mounting groove that links to each other with flexible hinge (101) one by one for install piezoelectric actuator (3) through the mounting groove.

3. A multi-mode driving piezoelectric thread motor according to claim 1 or 2, wherein the piezoelectric driver (3) is provided with insulating spacers (301) at both ends.

4. A multi-mode driving piezoelectric screw motor according to claim 3, wherein the side surface of the stator plate (10) is provided with screw through holes which are communicated with the mounting grooves one by one, and is in screw connection with a set screw (7) for realizing the adjustment of the pre-pressure of the piezoelectric driver (3) by extruding the end part of the set screw (7) through the end part of the piezoelectric driver (3).

5. A multi-mode driving piezoelectric thread motor according to claim 4, wherein the set screw (7) is screw-fitted with a lock nut (701) for locking the set screw (7).

6. A multi-mode driving piezoelectric thread motor according to claim 1, wherein the end of the screw (4) is provided with a curved surface structure for realizing point contact with the end face of the output shaft (5) through the curved surface structure (401).

7. A multi-mode driving piezoelectric thread motor according to claim 6, wherein the end face of the screw (4) is provided with a caulking groove, and a sphere (401) is fixedly connected with the end face of the output shaft (5) through the caulking groove, so as to realize point contact with the end face of the output shaft (5) through the sphere (401).

8. A multi-mode driving piezoelectric thread motor according to claim 1, wherein the four piezoelectric drivers (3) are symmetrically arranged with respect to the centers of the screw holes (103) in pairs, and the two piezoelectric drivers (3) in opposition are wired in opposite directions.

9. A method of exciting a multimode driven piezoelectric thread motor according to any one of claims 1 to 7, comprising:

In a static mode, the same direct current is applied to the four piezoelectric drivers (3), so that high-precision micro-positioning of the piezoelectric thread motor is realized;

in a quasi-static mode, the same sawtooth wave excitation signals are applied to the four piezoelectric drivers (3), so that low-frequency and high-precision movement of the piezoelectric thread motor is realized.

10. The excitation method of a multimode driving piezoelectric thread motor according to claim 8, further comprising a resonant mode, wherein the high-speed movement of the piezoelectric thread motor is achieved by applying sine wave excitation signals to two opposite piezoelectric drivers (3) and by applying sine wave excitation signals having phases different by 90 ° to the other two opposite piezoelectric drivers (3).