CN104506081A - Cylindrical piezoelectric motor capable of generating spiral linear movement - Google Patents

Abstract

The invention discloses a cylindrical piezoelectric motor that produces spiral linear motion, including a stator and a rotor. The stator is composed of a piezoelectric ceramic outer cylinder and an elastic inner cylinder; the stator and the rotor are provided with mutually matched threads, and Through the screw pair transmission, a pair of AC signals are applied to the piezoelectric ceramic outer cylinder of the stator, which can excite the stator to generate traveling waves along the circumferential direction. Driven by the screw pair, the rotor generates a helical linear motion output. The present invention can solve the problems of complex structure and difficulty in miniaturization of the existing rotary linear piezoelectric motor, can save other transmission mechanisms, has a simple structure, and can be better suitable for miniaturization, especially in the field of precision driving, especially in micro-optical modules It has important application prospects.

Description

A Cylindrical Piezoelectric Motor Produces Helical Linear Motion

technical field

The invention belongs to the technical field of precision driving and positioning, and relates to a helical linear piezoelectric motor, in particular to a cylindrical piezoelectric motor for generating helical linear motion.

Background technique

Piezoelectric motor is a kind of vibrator (or stator) that uses the inverse piezoelectric effect of piezoelectric elements to excite the vibrator (or stator) to generate micro-amplitude, high-frequency ultrasonic vibration, and forms a particle motion with a specific trajectory at a specific point or area on the vibrator surface. A new type of motor that achieves mechanical energy output through frictional coupling with the mover. The piezoelectric motor has the advantages of compact structure, low speed and high torque, fast response, self-locking when power off, and no magnetoelectric interference. As a new type of drive, it has a very wide range of applications. , robotics, precision machinery and other fields.

According to the different output forms of movers, piezoelectric motors can be divided into several output types such as linear, rotary and multi-degree-of-freedom. The rotary linear ultrasonic motor is one of the current output types of piezoelectric motors. The vibrator and the mover are mainly driven by a thread pair, and the output of the two degrees of freedom of the rotating line—the helical linear motion is realized through the thread pair transmission. Compared with other types of ultrasonic motors, rotary linear ultrasonic motors have the advantages of simple structure, easy miniaturization, and high positioning accuracy, and can be widely used in the technical field of precision drive and transmission.

The Chinese patent with the publication number CN1767347 discloses a thread-driven polyhedral ultrasonic motor. 4-12 piezoelectric elements are pasted on the plane outside the metal thin-walled cylindrical stator. The rotor and the metal thin-walled cylindrical stator are meshed through threads. The electric sheet makes the in-plane bending traveling wave along the circumferential direction in the stator, which directly drives the rotor to rotate through the screw thread and converts it into the helical linear motion of the rotor. However, the rotor of this motor has a polyhedron tube structure, and multiple piezoelectric ceramic sheets are pasted on each face of the polyhedron to form a driving body, which requires high processing requirements and complicated manufacturing procedures, which is a major obstacle for mass production and miniaturization of motors. To solve technical problems such as complex manufacturing process.

The U.S. patent with the publication number US6940209 discloses a rod-shaped linear piezoelectric motor, which uses two piezoelectric stack elements to generate a "hula hoop" (wobbling) motion at both ends, and pushes a motor inserted into it through the principle of screw drive. The inner screw produces linear motion, which can be made into a small-diameter rod-shaped structure, but its size in the length direction is relatively large, which is not suitable for making ultra-thin lens modules. In addition, the disadvantage of this motor is that it requires more auxiliary mechanical structures.

Contents of the invention

In order to overcome the deficiencies of the prior art above, the present invention provides a cylindrical piezoelectric motor that can produce spiral linear motion. The stator and rotor can directly generate motion through threads to realize two degrees of freedom of rotation and linear motion. Omitting other transmission mechanisms makes the structure simpler and more compact, and can better adapt to miniaturization and mass production.

The technical scheme provided by the invention is:

A cylindrical piezoelectric motor that produces spiral linear motion, including a stator and a rotor, the stator includes a piezoelectric ceramic outer cylinder and an elastic inner cylinder with threads on the inner surface; the rotor is a hollow cylinder with external threads Elastomer ring; the external thread of the rotor coincides with the thread on the inner surface of the elastic inner cylinder of the stator and is screwed into the stator; the stator and the rotor are driven by thread pairs to realize the helical linear motion of the rotor output.

In the above piezoelectric motor, the piezoelectric ceramic outer cylinder is polarized along the direction of the cylinder wall, and the inner and outer walls of the cylinder are respectively plated with electrodes. The electrodes on the inner wall are integrated, and the electrodes on the outer wall are divided into multiple regions along the circumferential direction. Each area is an electrode; the electrodes on the inner wall of the piezoelectric ceramic outer cylinder are grounded, and a plurality of electrodes on the outer wall are connected to a pair of high-frequency AC excitation signals; the piezoelectric ceramic outer cylinder of the stator is connected to the pair of high-frequency AC excitation signals Under the excitation of the excitation signal, two bending resonance vibration modes with a phase difference are excited, and the superimposed coupling forms a traveling wave propagating along the inner and outer circumferential directions of the elastic body of the stator; through the traveling wave and the connection between the stator and the rotor Between the thread pair, the stator drives the rotor to make a helical linear motion along the stator axis.

In the above-mentioned piezoelectric motor, the outer wall of the piezoelectric ceramic outer cylinder is divided into multiple regions, specifically divided into multiples of four regions along the circumferential direction; in one embodiment of the present invention, the electrodes of the outer wall of the piezoelectric ceramic outer cylinder There are eight electrodes, which are electrodes 11 to 18 in clockwise order, the electrodes 11 and 15 are the A1 excitation group, the electrodes 13 and 17 are the A2 excitation group, and the A1 and A2 excitation groups form the A excitation group; The electrodes 12 and 16 are the B1 excitation group, the electrodes 14 and 18 are the B2 excitation group, and the B1 and B2 excitation groups form the B excitation group; The excitation signals are two ultrasonic frequency electrical signals with the same frequency and the same voltage amplitude but different phases. In the embodiment of the present invention, the two ultrasonic frequency electric signals have phase difference.

In the above piezoelectric motor, the piezoelectric ceramic outer cylinder and the elastic inner cylinder are consolidated by gluing or cold welding. The material of the stator and the rotor elastic body is titanium alloy, copper alloy, alloy steel, aluminum alloy or high-strength elastic polymer. High-strength elastic polymers are engineering plastics such as polyamide (PA), polycarbonate (PC), polyoxymethylene (POM), polyphenylene oxide (PPO), and polyetheretherketone (PEEK).

The piezoelectric ceramics of the piezoelectric ceramic outer cylinder are lead zirconate titanate series ceramics with strong piezoelectric effect or lead-free piezoelectric ceramics with excellent piezoelectric properties, including barium titanate (BaTiO ₃ )-based lead-free piezoelectric ceramics , sodium bismuth titanate ((Bi _0.5 Na _0.5 )TiO ₃ ) based lead-free piezoelectric ceramics and alkali metal potassium sodium niobate ((K,Na)NbO ₃ ) based lead-free piezoelectric ceramics, etc.

In the piezoelectric motor described above, the hollow part of the rotor is used to fix the components to be driven.

Compared with prior art, the beneficial effect of the present invention is:

The stator and rotor of the piezoelectric motor provided by the present invention directly produce two degrees of freedom of rotation and linear motion through threads, which can save other transmission mechanisms and greatly reduce the volume of the piezoelectric motor system. Its structure is simple and compact. The manufacturing process is simplified, which can solve the problems of the existing rotary linear piezoelectric motor, such as complex structure and difficulty in miniaturization, and can better adapt to miniaturization and mass production. It has important applications in the field of precision drives, especially in micro-optical modules. prospect.

Description of drawings

Fig. 1 is the three-dimensional structure schematic diagram of the present invention;

Among them, 1—piezoelectric ceramic outer cylinder; 2—elastic inner cylinder; 3—rotor.

Fig. 2 is a structural schematic diagram of a piezoelectric ceramic outer cylinder in an embodiment of the present invention, and the outer electrode is divided into eight (4×2) equal parts along the circumference;

Fig. 3 is a top view of the piezoelectric ceramic outer cylinder in the embodiment of the present invention;

Fig. 4 is a structural schematic diagram of the piezoelectric ceramic outer cylinder adopting the first voltage excitation method in the embodiment of the present invention;

Fig. 5 is a structural schematic diagram of the piezoelectric ceramic outer cylinder adopting the second voltage excitation method in the embodiment of the present invention;

In Figures 2 to 5, 11 to 18 are eight electrodes that divide the external electrodes equally, among which, electrodes 11 and 15 are A1 excitation group, electrodes 13 and 17 are A2 excitation group, A1 and A2 excitation group constitute A vibration group, electrodes 12 and 16 are B1 vibration group, electrodes 14 and 18 are B2 vibration group; B1 and B2 vibration group constitute B vibration group; 19 is the inner electrode;

In Figures 4 to 5, ω—angular frequency of high-frequency AC signal; t—time.

6 is a schematic diagram of a bending vibration mode of a piezoelectric ceramic outer cylinder under voltage excitation in an embodiment of the present invention;

Among them, (a) is the standing wave resonant vibration generated by the piezoelectric ceramic outer cylinder by applying the alternating signal to the excitation group A alone; (b) is the alternating signal applied to the excitation group B alone, and the piezoelectric ceramic outer cylinder The standing wave resonant vibration generated by the barrel.

Detailed ways

Below in conjunction with accompanying drawing, further describe the present invention through embodiment, but do not limit the scope of the present invention in any way.

Fig. 1 is the three-dimensional structure schematic diagram of the present invention; Fig. 2 is the structural representation of piezoelectric ceramic outer cylinder in the embodiment of the present invention, and external electrode is divided into eight (4 * 2) equal parts along the circumference; Fig. 3 is the embodiment of the present invention Top view of the outer cylinder of the medium piezoelectric ceramic. It can be seen from the figure that the cylindrical piezoelectric motor capable of generating helical linear motion provided by the present invention is mainly composed of a piezoelectric ceramic outer cylinder 1 , an elastic inner cylinder 2 and a rotor 3 .

Wherein, the piezoelectric ceramic outer cylinder 1 is polarized along the direction of the cylinder wall. The piezoelectric ceramic outer cylinder 1 is plated with electrodes on the inner and outer sides of the cylinder wall, the inner electrode 19 is an integral electrode, and the outer electrode of the cylinder wall is divided into eight parts (the number of divided electrodes can be an integer multiple of 4) , the external electrodes are electrodes 11 , 12 , 13 , 14 , 15 , 16 , 17 , and 18 . The piezoelectric ceramic outer cylinder 1 is consolidated with the elastic inner cylinder 2 through gluing (epoxy resin) or cold welding process, and the piezoelectric ceramic outer cylinder 1 and the elastic inner cylinder 2 together form a stator.

The rotor 3 is a hollow elastomeric ring with external threads, and elements to be driven (such as lenses) can be fixed inside the rotor 3 . The rotor 3 is externally threaded, and the transmission between the rotor 3 and the elastic inner cylinder 2 is realized through a thread pair.

Among the external electrodes of the piezoelectric ceramic outer cylinder, the electrodes 11 and 15 are symmetrically distributed along the diameter direction of the piezoelectric ceramic outer cylinder, which is called the A1 excitation group; the electrodes 13 and 17 are also arranged along the piezoelectric ceramic outer cylinder. The symmetrical distribution in the diameter direction is called the A2 excitation group; the A1 excitation group and the A2 excitation group form the A excitation group. The electrodes 12 and 16 are also distributed symmetrically along the diameter of the piezoelectric ceramic outer cylinder, which is called the B1 excitation group; the electrodes 14 and 18 are also symmetrically distributed along the diameter of the piezoelectric ceramic outer cylinder, which is called the B2 excitation group. group; B1 excitation group and B2 excitation group constitute the B excitation group.

The excitation method of this embodiment: it will be described with reference to FIG. 4 , FIG. 5 and FIG. 6 . In the A1 excitation group, the alternating signal of elongation or shortening deformation is applied to the A1 excitation group alone, and the alternating signal of shortening or elongation deformation is applied to the A2 excitation group, because of the inverse piezoelectric effect effect, respectively produce elongation and contraction deformation in two perpendicular directions, and the entire piezoelectric ceramic outer cylinder will produce a standing wave resonant vibration R1 as shown in Figure 6(a). Separately apply alternating signals to the B1 excitation group in the B excitation group to cause it to produce elongation or shortening deformation, and B2 excitation group to apply an alternating signal to cause it to generate shortening or elongation deformation, because of the inverse piezoelectric effect , respectively produce elongation and contraction deformation in two perpendicular directions, and the entire piezoelectric ceramic outer cylinder will produce a standing wave resonant vibration R2 as shown in Figure 6(b). There is a 45° angle difference between the standing wave resonance vibration R1 and R2 in space.

The frequency of the alternating signal connected to the excitation group A and the excitation group B is the same, both in the ultrasonic frequency band, and the voltage amplitude is the same, but there is phase difference. When the excitation group A and the excitation group B are excited at the same time, the piezoelectric ceramic outer cylinder 1 will simultaneously excite two standing wave resonance vibrations of R1 and R2, and their superposition will be coupled to form a traveling wave resonance vibration. Among them, when the phase difference of the alternating signal loaded on the excitation group A and the excitation group B satisfies When the orthogonal relationship is shown in Figure 4, the excitation group A and the excitation group B excite the piezoelectric ceramic outer cylinder 1 to generate traveling waves of two wavelengths, and the entire stator will also vibrate accordingly, and through the screw pair transmission, Drive the rotor 3 clockwise to spiral and output linearly. When the phase difference of the alternating signal loaded on the excitation group A and the excitation group B satisfies When the orthogonal relationship is shown in Figure 5, the excitation group A and the excitation group B excite the piezoelectric ceramic outer cylinder 1 to generate reverse traveling waves of two wavelengths, and the entire stator will also vibrate accordingly. Transmission, driving the rotor 3 counterclockwise spiral linear output.

It should be noted that the purpose of the disclosed embodiments is to help further understand the present invention, but those skilled in the art can understand that various replacements and modifications are possible without departing from the spirit and scope of the present invention and the appended claims of. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the protection scope of the present invention is subject to the scope defined in the claims.

Claims (10)

1. produce a cylindric piezo-electric motor for spiral rectilinear motion, comprise stator and rotor, it is characterized in that, described stator comprises piezoelectric ceramic outer cylinder and the threaded elastomer inner cylinder of inner surface belt; Described rotor is for having externally threaded hollow elasticity body annulus; The screw thread kissing of the external screw thread of described rotor and the elastomer inner cylinder inner surface of described stator merges and screws in stator; Described stator and described rotor are by screw thread pair transmission, thus the spiral rectilinear motion realizing rotor exports.

2. piezo-electric motor as claimed in claim 1, it is characterized in that, the piezoelectric ceramic outer cylinder of described stator is along barrel direction polarization, electrode is coated with respectively at the inside and outside wall of cylinder, the electrode of inwall is an entirety, and the electrode of outer wall is along the circumferential direction divided into multiple region, and each region is an electrode; The electrode grounding of described piezoelectric ceramic outer cylinder inwall, multiple electrodes of outer wall connect a pair high-frequency AC excitation signal; The piezoelectric ceramic outer cylinder of described stator, under the excitation of described a pair high-frequency AC excitation signal, inspires two dephased crooked syntony mode of oscillations of tool, is formed along the row ripple that the elastomer internal and external circumference direction of described stator is propagated through superposition coupling; By described row ripple and the screw thread pair between stator and rotor, described stator drives described rotor to spin rectilinear motion along stator shaft orientation.

3. piezo-electric motor as claimed in claim 2, it is characterized in that, the outer wall of described piezoelectric ceramic outer cylinder is divided into multiple region, is specifically along the circumferential direction divided into doubly several regions of four.

4. piezo-electric motor as claimed in claim 2, it is characterized in that, the electrode of the outer wall of described piezoelectric ceramic outer cylinder is eight, electrode 11 ~ electrode 18 is followed successively by by clock-wise order, described electrode 11 and 15 is A1 exciting group, and electrode 13 and 17 is A2 exciting group, A1 and A2 exciting group forms A exciting group; Electrode 12 and 16 is B1 exciting group, and electrode 14 and 18 is B2 exciting group, B1 and B2 exciting group forms B exciting group; A pair high-frequency AC excitation signal that described A exciting group and B exciting group are connected is two, and frequency is identical, voltage magnitude is identical, but the supersonic frequency signal of telecommunication that phase place is different.

5. piezo-electric motor as claimed in claim 4, it is characterized in that, the phase difference of described a pair high-frequency AC excitation signal is

6. piezo-electric motor as claimed in claim 1, it is characterized in that, described piezoelectric ceramic outer cylinder and elastomer inner cylinder are by gluing or cold welding technique consolidation.

7. piezo-electric motor as claimed in claim 1, it is characterized in that, the elastomeric material of described stators and rotators is titanium alloy, copper alloy, steel alloy, aluminium alloy or high strength elastic high molecular polymer; Described high strength elastic high molecular polymer is polyamide, Merlon, polyformaldehyde, polyphenylene oxide or polyether-ether-ketone.

8. piezo-electric motor as claimed in claim 1, it is characterized in that, the piezoelectric ceramic of described piezoelectric ceramic outer cylinder is lead zirconate titanate series ceramic or leadless piezoelectric ceramics.

9. piezo-electric motor as claimed in claim 8, it is characterized in that, described leadless piezoelectric ceramics comprises barium titanate-based lead-free piezoelectric ceramic, bismuth-sodium titanate base lead-free piezoelectric ceramic and alkali metal potassium niobate sodium-based leadless piezoelectric ceramic.

10. piezo-electric motor as claimed in claim 1, is characterized in that, the hollow space of described rotor is used for the fixing element needing to drive.