Variable stiffness inertial impact linear piezoelectric motor

Abstract

The present application belongs to the field of precision driving and positioning technology, and particularly relates to a variable stiffness inertial impact linear piezoelectric motor. The piezoelectric motor comprises a base, a piezoelectric elastic vibrator, a stiffness adjusting mechanism, a first side clamping block and a second side clamping block. The first side clamping block and the second side clamping block clamp the substrate from the two sides of the middle part of the substrate. The stiffness adjusting mechanism can change the fitting position of the pair of stop blocks and the corresponding side surface of the substrate, thereby changing the clamping stiffness of the two sides. The two pairs of mass blocks at the two ends of the substrate make the reciprocating inertial impact force generated by the piezoelectric motor itself different during the reciprocating swing process. The difference in the reciprocating inertial impact force will be converted into the difference in the reciprocating swing displacement of the piezoelectric motor. Under the time accumulation, the piezoelectric motor will realize linear motion. By changing the clamping stiffness through the stiffness adjusting mechanism, the piezoelectric motor can obtain different running speeds and step distances to meet the needs of different loads and different working conditions, and has strong applicability.

Description

Technical Field

[0001] This invention belongs to the field of precision drive and positioning technology, specifically, it relates to a variable stiffness inertial impact linear piezoelectric motor. Background Technology

[0002] In recent decades, piezoelectric motors have developed rapidly due to the increasing demand for actuators in engineering applications and the advancement of precision manufacturing technology. Piezoelectric motors utilize the inverse piezoelectric effect of piezoelectric materials to convert input electrical energy into output mechanical energy. Compared with traditional electromagnetic piezoelectric motors, piezoelectric motors have advantages such as small size, fast response, and no electromagnetic interference. Currently, piezoelectric motors are widely used in micro-robotics, aerospace equipment, biomedicine, optical measurement, and other fields. Piezoelectric motors come in many structural types, and based on their working principle, they can be mainly divided into ultrasonic piezoelectric motors, inchworm piezoelectric motors, and inertial impact piezoelectric motors.

[0003] An inertial impact piezoelectric motor is a type of piezoelectric motor that uses the inertial impact of the stator to achieve linear motion or rotation of the rotor. This type of piezoelectric motor has the advantages of large stroke, simple structure, high resolution, and miniaturization.

[0004] Based on different driving mechanisms, inertial impact piezoelectric motors can be divided into two types: asymmetric electrical signal type and asymmetric mechanical structure type. Asymmetric electrical signal type inertial impact piezoelectric motors achieve unidirectional motion by inputting an asymmetric excitation voltage signal, causing the stator to generate an asymmetric inertial impact force. This type of piezoelectric motor operates in a quasi-static state and has high resolution and fast response speed; however, the performance of the piezoelectric element material is difficult to fully utilize, resulting in poor output performance.

[0005] Asymmetric mechanical structure inertial impact piezoelectric motors employ an asymmetric mechanical structure design. They are driven by a symmetrical excitation voltage signal to achieve directional motion. However, most inertial impact piezoelectric motors based on asymmetric mechanical structure design can only achieve unidirectional motion and cannot change the output speed and step size according to actual working conditions without changing the excitation signal source voltage. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of asymmetric electrical signal inertial impact piezoelectric motors, which operate under quasi-static conditions, resulting in poor output performance due to the inability to fully utilize the piezoelectric element material properties, and the fact that most asymmetric mechanical structure inertial impact piezoelectric motors can only achieve unidirectional motion and cannot change the output speed and step size according to actual working conditions without changing the excitation signal source voltage. This invention provides a variable stiffness inertial impact linear piezoelectric motor.

[0007] The present invention adopts the following technical solution:

[0008] A variable stiffness inertial impact linear piezoelectric motor includes a base 1, a piezoelectric elastic vibrator 3, a stiffness adjustment mechanism 2, a first side clamping block 4, and a second side clamping block 5.

[0009] The piezoelectric elastic oscillator 3 includes a substrate 31, a piezoelectric ceramic sheet assembly, and a mass block assembly.

[0010] The substrate 31 is a long rectangular sheet. The rectangular sheet is arranged horizontally along the base 1 and stands upright on the upper end of the base 1. The first side clamping block 4 and the second side clamping block 5 clamp and fix the rectangular sheet from the middle of both sides.

[0011] The rectangular sheet has symmetrical piezoelectric ceramic sheet groups and mass block groups at both ends. Each piezoelectric ceramic sheet group includes a pair of piezoelectric ceramic sheets 32 that are attached to the two sides of the rectangular sheet, and each mass block group includes a pair of mass blocks 33 that are attached to the two sides of the ends of the rectangular sheet.

[0012] The stiffness adjustment mechanism 2 includes a pair of stops 21, a stop adjustment block 22, and an adjustment bolt 23;

[0013] The pair of stops 21 are symmetrically located on both sides of the second clamping block 5, and one end face of the pair of stops 21 is attached to the corresponding side face of the substrate 31, while the other end of the pair of stops 21 is provided with a pair of inclined surfaces.

[0014] The stop adjustment block 22 is a horizontal wedge block. The adjustment bolt 23 passes horizontally through the stop adjustment block 22 and is fixedly connected to the second side clamping block 5. Rotating the adjustment bolt 23 causes the two sides of the stop adjustment block 22 to slide against a pair of inclined surfaces 24, so that a pair of stops 21 can move closer or further away along the length direction of the substrate 31.

[0015] During operation, a first-order harmonic excitation signal is input to each pair of piezoelectric ceramic sheets 32. The excitation of each pair of piezoelectric ceramic sheets 32 causes the substrate 31 to resonate in the first order. Due to the different clamping stiffness on both sides of the substrate 31, the reciprocating inertial impact force generated by the piezoelectric motor itself is different, which causes the piezoelectric motor to oscillate back and forth and generate a displacement difference. The cyclic excitation signal realizes the linear motion of the piezoelectric motor. When a second-order harmonic excitation signal is input to each pair of piezoelectric ceramic sheets 32, the substrate 31 resonates in the second order. The difference in reciprocating inertial impact force generated by the piezoelectric motor forms a reciprocating oscillation displacement difference. The cyclic excitation signal realizes the reverse linear motion of the piezoelectric motor.

[0016] Furthermore, the base 1 is a square plate, and a dovetail groove 11 is longitudinally provided in the middle of the base 1;

[0017] The lower end of the stop adjustment block 22 is located in the dovetail groove 11 through the dovetail slider. Rotating the adjustment bolt 23 causes the stop adjustment block 22 to move along the longitudinal direction of the base 1, and the two sides of the stop adjustment block 22 slide against a pair of inclined surfaces 24, so that a pair of stops 21 move closer or further away along the length direction of the substrate 31.

[0018] Furthermore, when the pair of stop blocks 21 are engaged, a rectangular groove is formed at one end of the substrate 31, and the second side clamping block 5 is located in the rectangular groove; when the pair of stop blocks 21 are moved away to the maximum distance, the stop block adjusting block 22 moves to the second side clamping block 5; the adjustment distance between the pair of stop blocks 21 is 0~4mm.

[0019] Furthermore, when the adjustment distance between the pair of stops 21 is 2mm, that is, when the distance between the corresponding sides of the stops and the second side clamping block 5 is 1mm;

[0020] With an input first-order resonant frequency of 90 Hz and a voltage of 240V... p-p Under first-order resonant frequency excitation, the no-load speed and displacement resolution of the piezoelectric motor are 20.457 mm / s and 0.22 mm, respectively; under second-order resonant frequency input of 601 Hz and 240 V, the speed and displacement resolution are 20.457 mm / s and 0.22 mm, respectively. p-p Under second-order resonant signal excitation, the piezoelectric motor has a reverse output speed of 13.126 mm / s and a displacement resolution of 0.02 mm.

[0021] Furthermore, the lower end of the second side clamping block 5 is slidably fitted within the dovetail groove 11 via a dovetail slider, so that the second side clamping block 5 is attached to one side of the middle portion of the substrate 31.

[0022] The first side clamping block 4 is an inverted "T" shape, and the horizontal part is fixed to the base 1 by bolts, while the vertical part is attached to the other side of the middle part of the substrate 31.

[0023] A pair of bolts pass through the second side clamping block 5, the middle of the substrate 31 and the first side clamping block 4 in sequence, so that the substrate 31 is fixed to the base 1 along the transverse direction of the base 1.

[0024] Furthermore, the lower ends of the opposite outer sides of the pair of blocks 21 are respectively provided with horizontal mounting plates 211, and each mounting plate 211 is provided with a pair of waist-shaped grooves;

[0025] The upper end of the base 1 is provided with a pair of mounting platforms 12 corresponding to one side of the second side clamping block 5. A pair of mounting plates of a pair of stops 21 are located on the pair of mounting platforms 12 and are fixedly connected by bolts and waist-shaped grooves.

[0026] Furthermore, each mounting platform is provided with a pair of transverse guards 13, and a pair of mounting plates are located on a pair of mounting platforms 12, so that the mounting plates are adjusted and fixed along the transverse direction of the base 1.

[0027] Furthermore, each of the piezoelectric ceramic sheets is made of lead zirconate titanate piezoelectric ceramic.

[0028] The beneficial technical effects of the present invention are as follows:

[0029] (1) A variable stiffness inertial impact linear piezoelectric motor of the present invention includes a base, a piezoelectric elastic vibrator, a stiffness adjustment mechanism, a first side clamping block and a second side clamping block; the first side clamping block and the second side clamping block clamp the substrate from both sides of the middle part of the substrate, wherein the stiffness adjustment mechanism can change the contact position of a pair of stops and the corresponding sides of the substrate, thereby changing the clamping stiffness on both sides, so that the two pairs of mass blocks at both ends of the substrate have different reciprocating inertial impact forces generated by the piezoelectric motor itself during the reciprocating swing process. The difference in reciprocating inertial impact force will be converted into the difference in reciprocating swing displacement of the piezoelectric motor. Over time, the piezoelectric motor will achieve linear motion. By changing the clamping stiffness through the stiffness adjustment mechanism, the piezoelectric motor can obtain different running speeds and step distances to meet the needs of different loads and different working conditions, and has strong applicability.

[0030] (2) The variable stiffness inertial impact linear piezoelectric motor of the present invention operates in a multi-order resonance state. Under the second-order resonance mode of the piezoelectric elastic oscillator, the piezoelectric motor can realize reverse linear motion. The piezoelectric element material of the piezoelectric elastic oscillator can give full play to the characteristics of fast response speed and high power density, thereby improving the output performance of the piezoelectric motor. When the stiffness adjustment distance of the piezoelectric motor prototype is 1 mm, its first-order resonance frequency is 90 Hz and the first-order resonance frequency of 240 Vp-p is excited. The no-load speed and displacement resolution of the piezoelectric motor prototype are 20.457 mm / s and 0.22 mm, respectively. Under the second-order resonance signal excitation of 601 Hz and 240 Vp-p, the reverse output speed of the piezoelectric motor prototype is 13.126 mm / s and the displacement resolution is 0.02 mm.

[0031] (3) The variable stiffness inertial impact linear piezoelectric motor of the present invention has a compact overall structure and simple signal control. Both bidirectional linear motion can achieve millimeter-level positioning, making it very suitable as a fine-tuning positioning device for precision machinery such as miniature scanning probe microscopes and fiber optic scanning systems. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of a variable stiffness inertial impact linear piezoelectric motor according to the present invention. Figure 1 .

[0033] Figure 2This is a schematic diagram of the structure of a variable stiffness inertial impact linear piezoelectric motor according to the present invention. Figure 2 .

[0034] Figure 3 This is a schematic diagram of the stiffness adjustment mechanism of the present invention.

[0035] Figure 4 This is a schematic diagram of the structure of the base of the present invention.

[0036] Figure 5 This is an exploded view of the stiffness adjustment mechanism of the present invention.

[0037] Figure 6 This is a schematic diagram of the structure of the stop adjustment block of the present invention.

[0038] Figure 7 This is a schematic diagram of the structure of the piezoelectric elastic oscillator of the present invention.

[0039] Figure 8 This is a schematic diagram of the structure of the clamping block of the present invention.

[0040] Figure 9 This is a schematic diagram of the structure of the clamping block of the present invention.

[0041] Figure 10 This is a schematic diagram illustrating the principle of the stiffness adjustment mechanism of the present invention, which adjusts the clamping stiffness.

[0042] Figure 11 This is a schematic diagram illustrating the working principle of the first-order resonant directional motion of the piezoelectric motor of the present invention.

[0043] Figure 12 This is a schematic diagram illustrating the working principle of the second-order resonant reverse motion of the piezoelectric motor of the present invention.

[0044] Figure 13 This is a diagram of the excitation electrical signal for the piezoelectric motor of the present invention.

[0045] The components include: base 1, piezoelectric elastic vibrator 3, stiffness adjustment mechanism 2, first side clamping block 4, second side clamping block 5, substrate 31, a pair of piezoelectric ceramic plates 32, a pair of mass blocks 33, a pair of stop blocks 21, stop block adjusting block 22, adjusting bolt 23, a pair of inclined surfaces 24, dovetail groove 11, mounting plate 211, a pair of mounting platforms 12, and a pair of transverse guards 13. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Example

[0047] See Figure 1A variable stiffness inertial impact linear piezoelectric motor includes a base 1, a piezoelectric elastic vibrator 3, a stiffness adjustment mechanism 2, a first side clamping block 4, and a second side clamping block 5.

[0048] See Figure 7 The piezoelectric elastic oscillator 3 includes a substrate 31, a piezoelectric ceramic sheet assembly, and a mass block assembly.

[0049] The substrate 31 is a long rectangular sheet. The rectangular sheet is arranged horizontally along the base 1 and stands upright on the upper end of the base 1. The first side clamping block 4 and the second side clamping block 5 clamp and fix the rectangular sheet from the middle of both sides.

[0050] The rectangular sheet has symmetrical piezoelectric ceramic sheet groups and mass block groups at both ends. Each piezoelectric ceramic sheet group includes a pair of piezoelectric ceramic sheets 32 that are attached to the two sides of the rectangular sheet, and each mass block group includes a pair of mass blocks 33 that are attached to the two sides of the ends of the rectangular sheet.

[0051] See Figure 3 and Figure 5 The stiffness adjustment mechanism 2 includes a pair of stops 21, a stop adjustment block 22, and an adjustment bolt 23;

[0052] The pair of stops 21 are symmetrically located on both sides of the second side clamping block 5, and one end face of the pair of stops 21 is attached to the corresponding side face of the substrate 31, and the other end of the pair of stops 21 is provided with a pair of inclined surfaces.

[0053] The stop adjustment block 22 is a horizontal wedge block. The adjustment bolt 23 passes horizontally through the stop adjustment block 22 and is fixedly connected to the second side clamping block 5. Rotating the adjustment bolt 23 causes the two sides of the stop adjustment block 22 to slide against a pair of inclined surfaces 24, so that a pair of stops 21 can move closer or further away along the length direction of the substrate 31.

[0054] The lower ends of the opposite outer sides of the pair of blocks 21 are respectively provided with horizontal mounting plates 211, and each mounting plate 211 is provided with a pair of waist-shaped grooves.

[0055] See Figure 4 The base 1 is a square plate, and a dovetail groove 11 is longitudinally provided in the middle of the base 1; a pair of mounting platforms 12 are provided on the upper end of the base 1 corresponding to one side of the second side clamping block 5, and a pair of mounting plates of a pair of stop blocks 21 are located on the pair of mounting platforms 12 and are fixedly connected by bolts and waist-shaped grooves. A pair of transverse side plates 13 are provided on each mounting platform, and a pair of mounting plates are located on the pair of mounting platforms 12, so that the mounting plates are adjusted and fixed along the transverse direction of the base 1.

[0056] See Figure 6The lower end of the stop adjustment block 22 is located in the dovetail groove 11 through the dovetail slider. Rotating the adjustment bolt 23 causes the stop adjustment block 22 to move along the longitudinal direction of the base 1, and the two sides of the stop adjustment block 22 slide against a pair of inclined surfaces 24, so that a pair of stops 21 move closer or further away along the length direction of the substrate 31.

[0057] See Figure 2 When a pair of stop blocks 21 are engaged, a rectangular groove is formed at one end of the substrate 31, and the second side clamping block 5 is located in the rectangular groove; when the pair of stop blocks 21 are moved away to the maximum distance, the stop block adjusting block 22 moves to the second side clamping block 5.

[0058] See Figure 10 The adjustment distance between the pair of stops 21 is 0~4mm.

[0059] See Figure 9 The lower end of the second side clamping block 5 is slidably fitted in the dovetail groove 11 through the dovetail slider, so that the second side clamping block 5 is attached to one side of the middle part of the substrate 31.

[0060] See Figure 8 The first side clamping block 4 is an inverted "T" shape, and the horizontal part is fixed to the base 1 by bolts, while the vertical part is attached to the other side of the middle part of the substrate 31.

[0061] A pair of bolts pass through the second side clamping block 5, the middle of the substrate 31 and the first side clamping block 4 in sequence, so that the substrate 31 is fixed to the base 1 along the transverse direction of the base 1.

[0062] Each of the piezoelectric ceramic sheets is made of lead zirconate titanate piezoelectric ceramic.

[0063] During operation, a first-order harmonic excitation signal is input to each pair of piezoelectric ceramic sheets 32. The excitation of each pair of piezoelectric ceramic sheets 32 causes the substrate 31 to resonate in the first order. Due to the different clamping stiffness on both sides of the substrate 31, the reciprocating inertial impact force generated by the piezoelectric motor itself is different, which causes the piezoelectric motor to oscillate back and forth and generate a displacement difference. The cyclic excitation signal realizes the linear motion of the piezoelectric motor. When a second-order harmonic excitation signal is input to each pair of piezoelectric ceramic sheets 32, the substrate 31 resonates in the second order. The difference in reciprocating inertial impact force generated by the piezoelectric motor forms a reciprocating oscillation displacement difference. The cyclic excitation signal realizes the reverse linear motion of the piezoelectric motor.

[0064] For details, see Figure 11 At time t0, the first harmonic excitation signal voltage applied to the piezoelectric elastic oscillator 3 is at its positive peak value. Under the action of the peak voltage, the motor piezoelectric elastic oscillator 3 maintains its backward swing to the limit position. At this time, the piezoelectric motor is in its initial position with a displacement of 0.

[0065] During the time interval from t0 to t1, the first harmonic excitation signal voltage supplied to the piezoelectric elastic oscillator 3 rapidly decreases from the positive peak value to the negative peak value. During this time interval, the motor piezoelectric elastic oscillator 3 rapidly swings from the rear limit position to the front limit position under the excitation of the voltage signal.

[0066] Because the effective clamping length of the second side clamping block 5 and the pair of stops 21 on the rear side of the motor piezoelectric elastic vibrator 3 is relatively long, the clamping stiffness of the motor piezoelectric elastic vibrator 3 is relatively large. Therefore, when the piezoelectric elastic vibrator 3 swings forward, the inertial impact force generated by the piezoelectric motor to the rear is relatively small, and the motor will generate a small displacement S1 to the rear.

[0067] At time t1, the first harmonic excitation signal voltage applied to the piezoelectric elastic oscillator 3 is at its negative peak. Under the action of the peak voltage, the motor piezoelectric elastic oscillator 3 maintains its forward swing to the limit position, and the motor remains stationary.

[0068] From t1 to t2, the first harmonic excitation signal voltage supplied to the piezoelectric elastic oscillator 3 rapidly rises from its negative peak value to its positive peak value. During this time period, the motor piezoelectric elastic oscillator 3, under the excitation of the voltage signal, rapidly swings from its front limit position to its rear limit position.

[0069] Because the effective clamping length of the first clamping block 4 on one side of the piezoelectric elastic oscillator 3 is relatively short, the clamping stiffness of the piezoelectric elastic oscillator 3 is relatively small. Therefore, when the piezoelectric elastic oscillator 3 swings backward, the inertial impact force generated by the piezoelectric motor moving forward is relatively large, and the motor will move forward and backward by a large displacement S2. The above four steps constitute the specific working process of the piezoelectric motor within one cycle of a first-order resonant excitation voltage signal. During this process, the motor completes a movement ΔS of one working cycle, with a length of (S2-S1) and a direction towards the long stop block side. When a periodic first-order harmonic excitation voltage signal is continuously applied to the motor, by continuously accumulating the small displacements generated in each cycle, the motor will achieve continuous directional macroscopic motion.

[0070] See Figure 12At time t0, the second harmonic excitation signal voltage supplied to the piezoelectric elastic oscillator 3 is at its positive peak. Under the action of the peak voltage, the motor piezoelectric elastic oscillator 3 maintains its extreme position where its middle part bends forward and its pair of end mass blocks 33 swing backward. At this time, the motor is in its initial position with a displacement of 0. During the time interval from t0 to t1, the second harmonic excitation signal voltage supplied to the piezoelectric elastic oscillator 3 rapidly decreases from its positive peak to its negative peak. During this time interval, under the excitation of the voltage signal, the middle part of the motor piezoelectric elastic oscillator 3 quickly swings backward, while the end mass blocks 33 swing to their forward extreme position. Because the effective clamping length of the first side clamping block 4 behind the motor piezoelectric elastic oscillator 3 is relatively short, the clamping stiffness of the motor piezoelectric elastic oscillator 3 is relatively small, so the inertial impact force generated by the piezoelectric motor backward is relatively large, and the motor will generate a large displacement L1 backward. At time t1, the second harmonic excitation signal voltage supplied to the piezoelectric elastic oscillator 3 is at its negative peak. Under the influence of the peak voltage, the piezoelectric vibrator 3 of the motor maintains its extreme position, with its middle section bent backward and its end mass block 33 swinging forward, while the motor remains stationary. From t1 to t2, the second harmonic excitation signal voltage supplied to the piezoelectric vibrator 3 rapidly rises from a negative peak to a positive peak. During this time period, under the excitation of the voltage signal, the middle section of the piezoelectric vibrator 3 quickly swings forward, and the pair of mass blocks 33 swing to their rear extreme positions. Because the effective clamping length of the second-side clamping block 5 and the pair of stops 21 on the front side of the piezoelectric vibrator 3 is relatively long, the clamping stiffness of the piezoelectric vibrator 3 is relatively large, so the inertial impact force generated by the piezoelectric motor forward is small, and the motor will move forward and backward by a small displacement L2. The above four steps are the specific working process of the piezoelectric motor within one second-order resonant excitation voltage signal cycle. During this process, the motor completes a movement ΔL of one working cycle, with a length of (L1-L2) and a direction in the direction of the short stop. When a second-order harmonic excitation voltage signal with a continuous cycle is applied to the motor, the motor will achieve continuous reverse macroscopic motion by continuously accumulating the tiny displacement generated in each cycle.

[0071] When the adjustment distance between the pair of stops 21 is 2 mm, that is, when the distance between each stop and the corresponding side of the second side clamping block 5 is 1 mm,

[0072] With an input first-order resonant frequency of 90 Hz and a voltage of 240V... p-p Under first-order resonant frequency excitation, the no-load speed and displacement resolution of the piezoelectric motor are 20.457 mm / s and 0.22 mm, respectively; under second-order resonant frequency input of 601 Hz and 240 V, the speed and displacement resolution are 20.457 mm / s and 0.22 mm, respectively. p-p Under second-order resonant signal excitation, the piezoelectric motor has a reverse output speed of 13.126 mm / s and a displacement resolution of 0.02 mm.

[0073] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A variable stiffness inertial impact linear piezoelectric motor, characterized in that: Includes a base (1), a piezoelectric elastic vibrator (3), a stiffness adjustment mechanism (2), a first side clamping block (4), and a second side clamping block (5); The piezoelectric elastic oscillator (3) includes a substrate (31), a piezoelectric ceramic sheet assembly, and a mass block assembly; The substrate (31) is a long rectangular sheet. The rectangular sheet is arranged horizontally along the base (1) and stands upright on the upper end of the base (1). The first side clamping block (4) and the second side clamping block (5) clamp and fix the rectangular sheet from the middle of both sides. The rectangular sheet has piezoelectric ceramic sheet groups and mass block groups symmetrically arranged at both ends. Each piezoelectric ceramic sheet group includes a pair of piezoelectric ceramic sheets (32) that are attached to the two sides of the rectangular sheet, and each mass block group includes a pair of mass blocks (33) that are attached to the two sides of the end of the rectangular sheet. The stiffness adjustment mechanism (2) includes a pair of stops (21), a stop adjustment block (22), and an adjustment bolt (23); The pair of stops (21) are symmetrically located on both sides of the second side clamping block (5), and one end face of the pair of stops (21) is attached to the corresponding side face of the substrate (31), and the other end of the pair of stops (21) is provided with a pair of inclined surfaces (24). The stop adjustment block (22) is a horizontal wedge block. The adjustment bolt (23) passes horizontally through the stop adjustment block (22) and is fixedly connected to the second side clamping block (5). Rotating the adjustment bolt (23) causes the two sides of the stop adjustment block (22) to slide against a pair of inclined surfaces (24), so that a pair of stops (21) move closer to or further away from the substrate (31) along the length direction. During operation, a first-order harmonic excitation signal is input to each pair of piezoelectric ceramic sheets (32). Each pair of piezoelectric ceramic sheets (32) is excited and drives the substrate (31) to resonate in the first order. Due to the different clamping stiffness on both sides of the substrate (31), the reciprocating inertial impact force generated by the piezoelectric motor itself is different, which causes the piezoelectric motor to oscillate back and forth and generate a displacement difference. The cyclic excitation signal realizes the linear motion of the piezoelectric motor. A second-order harmonic excitation signal is input to each pair of piezoelectric ceramic sheets (32), and the substrate (31) resonates in the second order. The difference in reciprocating inertial impact force generated by the piezoelectric motor forms a reciprocating oscillation displacement difference. The cyclic excitation signal realizes the reverse linear motion of the piezoelectric motor.

2. The variable stiffness inertial impact linear piezoelectric motor according to claim 1, characterized in that: The base (1) is a square plate, and a dovetail groove (11) is longitudinally provided in the middle of the base (1). The lower end of the stop adjustment block (22) is located in the dovetail groove (11) through the dovetail slider. Rotating the adjustment bolt (23) causes the stop adjustment block (22) to move along the longitudinal direction of the base (1), and the two sides of the stop adjustment block (22) slide against a pair of inclined surfaces (24), so that a pair of stops (21) move closer to or further away from the substrate (31) along the length direction.

3. The variable stiffness inertial impact linear piezoelectric motor according to claim 2, characterized in that: When a pair of stops (21) are engaged, a rectangular groove is formed at one end of the substrate (31), and the second side clamping block (5) is located in the rectangular groove; when the pair of stops (21) are moved away to the maximum distance, the stop adjusting block (22) moves to the second side clamping block (5); The adjustment distance between the pair of stops (21) is 0~4mm.

4. The variable stiffness inertial impact linear piezoelectric motor according to claim 3, characterized in that: When the adjustment distance between the pair of stops (21) is 2 mm, that is, when the distance between each stop and the corresponding side of the second side clamping block (5) is 1 mm, and the input first-order resonant frequency is 90 Hz and 240V, p-p Under first-order resonant frequency excitation, the no-load speed and displacement resolution of the piezoelectric motor are 20.457 mm / s and 0.22 mm, respectively; under second-order resonant frequency input of 601 Hz and 240 V, the speed and displacement resolution are 20.457 mm / s and 0.22 mm, respectively. p-p Under second-order resonant signal excitation, the piezoelectric motor has a reverse output speed of 13.126 mm / s and a displacement resolution of 0.02 mm.

5. The variable stiffness inertial impact linear piezoelectric motor according to claim 2, characterized in that: The lower end of the second side clamping block (5) is located in the dovetail groove (11) through a dovetail slider, so that the second side clamping block (5) is attached to one side of the middle part of the substrate (31); The first side clamping block (4) is an inverted "T" shape, and the horizontal part is fixed to the base (1) by bolts, while the vertical part is attached to the other side of the middle part of the substrate (31); A pair of bolts pass through the second side clamping block (5), the middle of the substrate (31) and the first side clamping block (4) in sequence, so that the substrate (31) is fixed on the base (1) along the transverse direction of the base (1).

6. The variable stiffness inertial impact linear piezoelectric motor according to claim 1, characterized in that: The lower ends of the opposite outer sides of the pair of blocks (21) are respectively provided with horizontal mounting plates (211), and each mounting plate (211) is provided with a pair of waist-shaped grooves; The upper end of the base (1) is provided with a pair of mounting platforms (12) corresponding to one side of the second side clamping block (5). A pair of mounting plates of a pair of stops (21) are located on the pair of mounting platforms (12) and are fixedly connected by bolts and waist-shaped grooves.

7. The variable stiffness inertial impact linear piezoelectric motor according to claim 6, characterized in that: Each mounting platform is provided with a pair of transverse guards (13), and a pair of mounting plates are located on a pair of mounting platforms (12) respectively, so that the mounting plates are adjusted and fixed along the transverse direction of the base (1).

8. The variable stiffness inertial impact linear piezoelectric motor according to claim 1, characterized in that: Each of the piezoelectric ceramic sheets is made of lead zirconate titanate piezoelectric ceramic.

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