Resonant impact linear motor and piezoelectric vibrator frequency matching method

Abstract

The application discloses a resonant impact type linear motor and a piezoelectric vibrator frequency matching method, and the piezoelectric vibrator is in the approximate sawtooth wave vibration under the resonant state through the first-order axial vibration mode and the second-order axial vibration mode at both ends of the piezoelectric vibrator, and is in the smooth movement along the linear optical axis under the asymmetric friction coupling effect; the resonant frequency theoretical ratio of the first-order axial vibration mode and the second-order axial vibration mode of the piezoelectric vibrator in the free state is close to 1:2, adjustment ring A and adjustment ring B are arranged at the vibration mode nodes, and the resonant frequency ratio is accurately adjusted to meet the 1:2 relationship by changing the proportion of the two kinds of material metal ring pieces. The application designs a piezoelectric vibrator which is convenient to mount and dismount, and provides a flexible frequency matching method, solves the frequency mismatching problem caused by the preparation difference of material characteristics and the machining tolerance of structure size, and guarantees the actual working effect of the resonant impact type piezoelectric motor.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric actuators, and more specifically to a resonant impact linear motor and a piezoelectric vibrator frequency matching method. Background Technology

[0002] Resonant impulse piezoelectric motors utilize multiple vibration modes of a piezoelectric oscillator to synthesize high-frequency, large-amplitude approximate sawtooth wave vibrations. Mechanical transmission is achieved through frictional coupling between the stator and mover, extending the driving state of the impulse piezoelectric motor from a quasi-static state to the resonant frequency. This results in advantages such as high speed, strong driving force, and high output power. Therefore, resonant impulse piezoelectric motors have significant development potential and application value in precision drive systems for rapid manipulation of biological samples, precise positioning of optical platforms, and sampling in extraterrestrial drilling.

[0003] In recent years, several patent applications have involved resonant impact piezoelectric motors and proposed frequency matching methods for piezoelectric oscillators. Patent application CN109378995A, entitled "A High-Frequency Resonant Piezoelectric Inertial Drive Linear Displacement Platform," consists of a base, a first piezoelectric actuator, a second piezoelectric actuator, a main inertial body, and an auxiliary inertial body, forming an asymmetric inertial mover (i.e., a piezoelectric oscillator). It has anti-phase natural vibration modes and in-phase natural vibration modes. The ratio of the anti-phase natural vibration frequency to the in-phase natural vibration frequency of the inertial mover is adjusted to 1:2 by changing the mass ratio of the base, the main inertial body, and the auxiliary inertial body. Patent application CN111082699A, entitled "A piezoelectric oscillator with non-sinusoidal periodic resonance", is composed of a matrix, a mass body, a U-shaped bracket, a support bracket, a bending bracket, and piezoelectric sheets. The piezoelectric oscillator has a first-order transverse vibration mode and a second-order transverse vibration mode. By changing the thickness ratio of the two bending brackets, the natural frequency ratio of the two vibration modes of the piezoelectric oscillator can be adjusted to 1:2 or 1:3. Two piezoelectric sheets are used to excite the two natural frequencies to generate sinusoidal resonance, so that the matrix of the piezoelectric oscillator exhibits an approximate sawtooth wave or square wave vibration in the synthesized resonance state.

[0004] The aforementioned piezoelectric vibrator is a key component of the resonant impact piezoelectric motor. It possesses two effective natural vibration modes, and the ratio of their resonant frequencies must satisfy a 1:2 relationship. Frequency matching requires specific structural design and parameter adjustments. However, the actual manufactured piezoelectric vibrator differs from the design parameters in terms of material properties and structural dimensions, resulting in an inaccurate 1:2 ratio of resonant frequencies, significantly reducing the motor's actual performance. Precise control of material properties and structural dimensions to ensure frequency matching would undoubtedly increase manufacturing costs considerably. Therefore, reliable structural design and flexible frequency matching methods remain key challenges in the development of resonant impact piezoelectric motors. Summary of the Invention

[0005] To overcome the shortcomings of the above-mentioned key technologies, this invention provides a resonant impact linear motor and a piezoelectric vibrator frequency matching method. By setting an adjustment structure at the vibration mode node of the piezoelectric vibrator, the resonant frequency ratio can be precisely adjusted to around 1:2, thereby solving the frequency mismatch problem caused by differences in material properties and structural dimension processing tolerances.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A resonant impact linear motor includes a piezoelectric vibrator, a linear optical axis, a base, and a base.

[0008] The piezoelectric vibrator has a symmetrical structure with a central sleeve. The outer ring of the central sleeve is coaxially arranged from the midpoint outwards as an adjusting ring A, a metal tube, a piezoelectric ring, an adjusting ring B, and a fastening nut. The two ends of the outer ring of the central sleeve and the outer end of the inner ring of the fastening nut are threaded. The adjusting ring A, the metal tube, the piezoelectric ring, the adjusting ring B and the central sleeve are fixed to the central sleeve as an integral structure by the fastening nut. The outer end of the fastening nut is provided with a boss, and pre-tensioning springs are installed on both sides of the boss.

[0009] The linear optical axis passes through the piezoelectric vibrator via a central sleeve and a pre-tightening spring. The pre-tightening spring contacts the linear optical axis and applies pre-tightening force through a screw.

[0010] The base is disposed on both sides of the base, the two bases are parallel to each other and perpendicular to the base, and the two ends of the linear optical axis are fixed by the bases mounted on the base;

[0011] The piezoelectric vibrator contains two inherent vibration modes, namely a first-order axial vibration mode and a second-order axial vibration mode, and the resonant frequency ratio f1:f2 of the two vibration modes satisfies a 1:2 relationship.

[0012] The adjustment rings A and B are composed of several metal rings. Adjustment ring A is located at 1 / 2 of the piezoelectric vibrator, which is the node of the first-order axial vibration mode. Adjustment ring B is located at 1 / 4 and 3 / 4 of the piezoelectric vibrator, respectively, which are the nodes of the second-order axial vibration modes.

[0013] To achieve the above objectives, using the aforementioned resonant impact linear motor, this invention also provides a piezoelectric vibrator frequency matching method, which includes the following steps:

[0014] Step 1: Test the resonant frequencies of the two vibration modes of the piezoelectric oscillator and calculate the resonant frequency ratio f1:f2;

[0015] Step 2: If the resonant frequency ratio f1:f2 is less than 1:2, replace part or all of the metal rings of the adjustment ring A with high-density, high-stiffness metal rings to increase the resonant frequency f1 of the first-order axial vibration mode and decrease the resonant frequency f2 of the second-order axial vibration mode, so that the resonant frequency ratio f1:f2 becomes larger and satisfies the 1:2 relationship.

[0016] Step 3: If the resonant frequency ratio f1:f2 is greater than 1:2, replace part or all of the metal rings of the adjustment ring B with high-density, high-stiffness metal rings to reduce the resonant frequency f1 of the first-order axial vibration mode and increase the resonant frequency f2 of the second-order axial vibration mode, so that the resonant frequency ratio f1:f2 becomes smaller and satisfies the 1:2 relationship.

[0017] Furthermore, the low-density, low-stiffness metal ring is made of aluminum alloy, while the high-density, high-stiffness metal ring is made of stainless steel.

[0018] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0019] (1) The piezoelectric vibrator of the present invention is a Langzhiwan vibrator composed of a central sleeve, an adjusting ring A, a metal round tube, a piezoelectric ring, an adjusting ring B, a fastening nut and a pre-tightening spring. It has strong power driving capability, and is easy to install and disassemble with low processing cost.

[0020] (2) The piezoelectric vibrator of the present invention adopts a symmetrical structure. The theoretical value of the resonant frequency ratio f1:f2 of the first-order axial vibration mode and the second-order axial vibration mode is 1:2, which avoids complex structural design.

[0021] (3) The frequency matching method of the present invention is accomplished by using an adjustment ring set at the vibration mode node of the piezoelectric vibrator. By changing the material properties of the adjustment ring, that is, replacing the low-density, low-stiffness material with a high-density, high-stiffness material, the resonant frequencies of the two vibration modes change in opposite directions to achieve the ratio change. Moreover, the adjustment ring A and the adjustment ring B have opposite adjustment effects, which can achieve a large frequency ratio adjustment range. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of the resonant impact linear motor of the present invention;

[0023] Figure 2 This is a schematic diagram of the resonant impact linear motor preload device of the present invention;

[0024] Figure 3 This is the first-order axial natural vibration mode of the piezoelectric vibrator of the present invention;

[0025] Figure 4This is the second-order axial natural vibration mode of the piezoelectric oscillator of the present invention;

[0026] Figure 5 This is a curve showing the relationship between the resonant frequency ratio of the piezoelectric oscillator of the present invention and the proportion of material A in the adjusting ring;

[0027] Figure 6 This is a curve showing the relationship between the resonant frequency ratio of the piezoelectric oscillator of the present invention and the proportion of material B in the adjusting ring;

[0028] Figure 7 This refers to the approximate sawtooth wave vibration under the synthetic resonance state of the piezoelectric oscillator of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figure 1 , 2 As shown, the piezoelectric vibrator 1 adopts a symmetrical structure. The piezoelectric vibrator 1 consists of a central sleeve 5, an adjusting ring A6, a metal tube 7, a piezoelectric ring 8, an adjusting ring B9, a fastening nut 10, and a pre-tightening spring 11. It is fixed as an integral structure by the threads at both ends of the outer ring of the central sleeve 5 and the outer end of the inner ring of the fastening nut 10. A boss 12 is provided at the outer end of the fastening nut 10, and pre-tightening springs 11 are installed on both sides of the boss 12.

[0031] like Figure 3 , 4 As shown, the first-order axial vibration mode and the second-order axial vibration mode under free state are selected to synthesize the resonant sawtooth wave vibration of piezoelectric oscillator 1. The node of the first-order axial vibration mode is located at 1 / 2 of piezoelectric oscillator 1, and the nodes of the second-order axial vibration mode are located at 1 / 4 and 3 / 4 of piezoelectric oscillator 1. These two vibration modes have the largest amplitude at both ends of the piezoelectric oscillator, which can provide a large power driving capability. Moreover, the ratio of the resonant frequencies is close to 1:2 under theoretical conditions, which provides convenience for the subsequent frequency matching process.

[0032] The following two cases will be used for explanation. It should be noted that there are 10 metal rings at adjustment ring A6, each with a thickness of 0.2mm, and 5 metal rings at each point of adjustment ring B9, for a total of 10 rings, each with a thickness of 0.2mm. Under the initial conditions, both adjustment ring A6 and adjustment ring B9 are made of aluminum alloy.

[0033] like Figure 5As shown, if the resonant frequency ratio f1:f2 of the finished piezoelectric oscillator 1 is less than 1:2, that is, when both the adjusting ring A6 and the adjusting ring B9 are made of aluminum alloy, the resonant frequency ratio f1:f2 is 1.76.

[0034] Replacing the six metal rings in the adjustment ring A6 located at 1 / 2 of the piezoelectric vibrator 1 with stainless steel instead of aluminum alloy can increase the resonant frequency ratio f1:f2 from 1.76 to 2.00, thereby meeting the frequency matching requirements.

[0035] like Figure 6 As shown, if the resonant frequency ratio f1:f2 of the finished piezoelectric vibrator 1 is greater than 1:2, that is, when both the adjusting ring A6 and the adjusting ring B9 are made of aluminum alloy, the resonant frequency ratio f1:f2 is 2.09.

[0036] Replacing the four metal rings in the adjustment ring B9 located at 1 / 4 and 3 / 4 of the piezoelectric vibrator 1 with stainless steel instead of aluminum alloy can reduce the resonant frequency ratio f1:f2 from 2.09 to 2.00, thereby meeting the frequency matching requirements.

[0037] like Figure 7 As shown, a sinusoidal voltage of frequency f is applied to the piezoelectric ring 8, and the piezoelectric oscillator 1 operates in the first-order axial vibration mode. The voltage amplitude is controlled to generate a sinusoidal resonance with an amplitude of A at both ends of the piezoelectric oscillator 1. A sinusoidal voltage of frequency 2f is applied to the piezoelectric ring 8, and the piezoelectric oscillator 1 operates in the second-order axial vibration mode. The voltage amplitude is controlled to generate a sinusoidal resonance with an amplitude of 0.5A at both ends of the piezoelectric oscillator 1. When the piezoelectric ring 8 simultaneously applies sinusoidal voltages of frequencies f and 2f, and the phase of the two sinusoidal voltages is controlled, the sinusoidal resonances of the two frequencies at both ends of the piezoelectric oscillator 1 are combined to form an approximate sawtooth wave vibration.

[0038] Specific working process and principles:

[0039] Based on the Fourier transform principle, the approximate sawtooth wave vibration required by the resonant impact linear motor can be considered as a synthesis of the fundamental frequency sinusoidal resonance and the second harmonic sinusoidal resonance, which can be expressed as:

[0040] x(t)=Asin2πft+0.5Asin4πft (1)

[0041] Where A is the amplitude of the sinusoidal resonance, and f is the frequency of the sinusoidal resonance.

[0042] like Figure 1 , 2As shown, the linear optical axis 2 passes through the piezoelectric vibrator 1 via the central sleeve 5 and the pre-tensioning spring 11. The pre-tensioning spring 11 contacts the linear optical axis 2 and applies pre-tension through the screw 13. The two ends of the linear optical axis 2 are fixed by the base 3 mounted on the base 4. The approximately sawtooth wave vibration at both ends of the piezoelectric vibrator 1 is frictionally coupled to the linear optical axis 2 through the pre-tensioning spring 11. Under the asymmetric frictional action of the resonant impact, the piezoelectric vibrator 1 produces a smooth unidirectional motion along the linear optical axis 2.

[0043] The above-described embodiments are merely examples of several implementations of the present invention, and are described in a relatively specific and detailed manner. However, they are not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention, and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A resonant impact linear motor, characterized in that, Includes piezoelectric vibrator, linear optical axis, base and base; The piezoelectric vibrator has a symmetrical structure with a central sleeve. The outer ring of the central sleeve is coaxially arranged from the midpoint outwards as an adjusting ring A, a metal tube, a piezoelectric ring, an adjusting ring B, and a fastening nut. The two ends of the outer ring of the central sleeve and the outer end of the inner ring of the fastening nut are threaded. The adjusting ring A, the metal tube, the piezoelectric ring, the adjusting ring B and the central sleeve are fixed to the central sleeve as an integral structure by the fastening nut. The outer end of the fastening nut is provided with a boss, and pre-tensioning springs are installed on both sides of the boss. The linear optical axis passes through the piezoelectric vibrator via a central sleeve and a pre-tightening spring. The pre-tightening spring contacts the linear optical axis and applies pre-tightening force through a screw. The base is disposed on both sides of the base, the two bases are parallel to each other and perpendicular to the base, and the two ends of the linear optical axis are fixed by the bases mounted on the base; The piezoelectric vibrator contains two inherent vibration modes, namely a first-order axial vibration mode and a second-order axial vibration mode, and the resonant frequency ratio f1:f2 of the two vibration modes satisfies a 1:2 relationship. Both the adjusting ring A and the adjusting ring B are composed of several metal ring pieces; Adjusting ring A is located at 1 / 2 of the piezoelectric vibrator, which is the node of the first-order axial vibration mode. Adjusting ring B is located at 1 / 4 and 3 / 4 of the piezoelectric vibrator, which are the nodes of the second-order axial vibration modes. The piezoelectric vibrator frequency matching method includes the following steps: Step 1: Test the resonant frequencies of the two vibration modes of the piezoelectric oscillator and calculate the resonant frequency ratio f1:f2; Step 2: If the resonant frequency ratio f1:f2 is less than 1:2, replace part or all of the metal rings of the adjustment ring A with high-density, high-stiffness metal rings to increase the resonant frequency f1 of the first-order axial vibration mode and decrease the resonant frequency f2 of the second-order axial vibration mode, so that the resonant frequency ratio f1:f2 becomes larger and satisfies the 1:2 relationship. Step 3: If the resonant frequency ratio f1:f2 is greater than 1:2, replace part or all of the metal rings of the adjustment ring B with high-density, high-stiffness metal rings to reduce the resonant frequency f1 of the first-order axial vibration mode and increase the resonant frequency f2 of the second-order axial vibration mode, so that the resonant frequency ratio f1:f2 becomes smaller and satisfies the 1:2 relationship.

2. The resonant impact linear motor according to claim 1, characterized in that, The material of the low-density, low-stiffness metal ring is aluminum alloy.

3. The resonant impact linear motor according to claim 1, characterized in that, The high-density, high-rigidity metal ring is made of stainless steel.

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