Symmetrically biased string self-clamping inertial rotary piezoelectric motor

Abstract

The present application belongs to the field of precision driving and positioning technology, and particularly relates to a symmetrical bias string self-clamping inertia rotary piezoelectric motor. The motor stator comprises a rectangular frame and a circular ring; the motor rotor comprises a pre-tightening mechanism, a rotating shaft and a pair of driving mechanisms; the pair of clamping feet of the pair of driving mechanisms are arranged in a central symmetry, and the symmetry center is the center of the circular ring; when a first-order resonant frequency sinusoidal electric signal is input, each pair of piezoelectric ceramic pieces is excited to drive the substrate to vibrate in the first order, and a cyclic excitation signal can realize continuous counterclockwise rotation of the motor; when a second-order resonant frequency sinusoidal electric signal is input, each pair of piezoelectric ceramic pieces is excited to drive the substrate to vibrate in the second order, and a cyclic excitation signal can realize continuous clockwise rotation of the motor. Therefore, the present application adopts a symmetrical layout in structure, has good running stability; the excitation signal adopted is a sinusoidal signal, and the control system is simple; there is no large sliding friction in the running process, and the service life of the motor is long.

Description

Technical Field

[0001] This invention belongs to the field of precision drive and positioning technology, specifically relating to a symmetrically biased chord self-clamping inertial rotary piezoelectric motor. Background Technology

[0002] A piezoelectric motor is a novel actuator that converts electrical energy into mechanical energy using the inverse piezoelectric effect of piezoelectric materials. In recent years, piezoelectric motors have been widely used in precision drive and positioning, biotechnology, medical equipment, aerospace technology, and other fields due to their advantages such as small size, high power density, fast response, and absence of electromagnetic interference. Based on their driving principle, piezoelectric motors can be broadly classified into three categories: ultrasonic motors, inchworm motors, and inertial impact motors. Ultrasonic motors generate ultrasonic standing or traveling waves by exciting piezoelectric devices with ultra-high frequency signals, which then drive the motor through friction. Because they operate in the ultrasonic field, they offer excellent noise control and, due to their high-frequency characteristics, can achieve high output speeds. However, they suffer from severe friction and wear, and significant limitations in size and shape. Inchworm motors are piezoelectric motors designed using biomimicry to mimic the walking patterns of insects in nature. They operate in a quasi-static state and possess advantages such as high displacement accuracy, large output force, high precision, and long lifespan. They are widely used in precision instruments and positioning technologies, but suffer from low output speeds. Inertial impact piezoelectric motors utilize asymmetrical inertial forces, typically achieved through asymmetrical mechanical structures and asymmetrical electrical signals. They offer good overall performance, but suffer from significant friction and wear, complex signal control systems, and can only move in one direction.

[0003] Unlike traditional inertial impact piezoelectric motors, this invention features a symmetrical layout, resulting in excellent motor stability. Furthermore, the excitation signal is a sinusoidal wave, simplifying the control system. The motor operates in a resonant state, and a special drive mechanism enables self-clamping, effectively suppressing inertial backlash and improving motion efficiency. The motor experiences minimal sliding friction during operation, leading to a long service life. Moreover, by incorporating different vibration modes of the piezoelectric ceramic, bidirectional motion of the motor is achieved. Summary of the Invention

[0004] In order to improve the working efficiency and service life of the motor and reduce the friction and wear of the motor, the present invention provides a symmetrically biased chord self-clamping inertial rotary piezoelectric motor.

[0005] The specific technical solution of the present invention is as follows: a symmetrical biased string self-clamping inertial rotary piezoelectric motor, comprising a motor stator 1 and a motor mover 2; The motor stator 1 includes a rectangular frame and a circular ring 13. The rectangular frame is arranged vertically, and the circular ring 13 is horizontally fixed to the middle of the lower frame plate of the rectangular frame through a pair of arc-shaped grooves. The motor actuator 2 includes a preload mechanism 22, a rotating shaft 23, and a pair of drive mechanisms 21. The pre-tightening mechanism 22 includes a central base block 224 and a pair of pre-tightening blocks 221. The central base block 224 is arranged on the lower frame plate corresponding to the center of the ring 13. The rotating shaft 23 vertically passes through the central axis of the central base block 224 and is fixed. The upper and lower ends of the rotating shaft 23 are rotatably connected to the upper and lower frame plates of the rectangular frame through a pair of bearings 14. Each preload block is in the shape of an inverted L-shape, and the right-angle connection part of the L-shape is provided with a single-axis symmetrical straight-circular flexible hinge. The lateral extension plate of the L-shape is engaged with the central base block 224 through a slot and fixed by the preload bolt 223, so that the longitudinal extension plate of the L-shape is located at the offset chord position of the ring 13. Each drive mechanism includes a substrate 212 and a pair of piezoelectric ceramic sheets 213. The substrate 212 is an upright, elongated rectangular sheet. One end of the rectangular sheet is fixedly connected to the L-shaped longitudinal extension of the pre-tightening block. The length direction of the rectangular sheet is parallel to the longitudinal direction of the central base block 224, so that the pair of substrates of the pair of drive mechanisms 21 are arranged at the longitudinal ends of the central base block 224 and are respectively located at the symmetrical offset chord position of the annulus 13. A pair of mass blocks 211 are provided on both sides of the other end of the rectangular sheet, and a clamping foot 2121 is provided on the lower end of the rectangular sheet in contact with the inner wall of the ring 13, so that the pair of clamping feet of the pair of driving mechanisms 21 are arranged in a centrally symmetrical manner, and the center of symmetry is the center of the ring 13. The pair of piezoelectric ceramic sheets 213 are respectively attached to the two sides of the substrate 212 between the clamping foot 2121 and the pair of mass blocks 211; When the pre-tightening bolt 223 is rotated, the lateral fixed position of the pre-tightening block on the central base block 224 can be adjusted, so that the base plate 212 deviates from or approaches the diameter of the ring 13, thereby adjusting the contact pre-tightening force between the clamping foot 2121 and the ring 13. During operation, each substrate 212 is connected to the negative terminal of the power supply, and each pair of piezoelectric ceramic sheets 213 is connected to the positive terminal of the power supply. When a sinusoidal electrical signal with a first-order resonant frequency is input, each pair of piezoelectric ceramic sheets 213 is excited and drives the substrate 212 to perform a first-order vibration. The motor mover 2 completes all the movements within one signal cycle, realizing that the rotating shaft 23 rotates a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the continuous counterclockwise rotation of the motor. When a sinusoidal electrical signal with a second-order resonant frequency is input, each pair of piezoelectric ceramic sheets 213 is excited, causing the substrate 212 to vibrate in a second order. The motor mover 2 completes all the motion within one signal cycle, realizing that the rotating shaft 23 rotates a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the motor to rotate continuously clockwise.

[0006] Furthermore, when the input sinusoidal electrical signal voltage with a first-order resonant frequency of 240 VP-P and a frequency of 150 Hz is used, the piezoelectric motor achieves a 0.016 rad angular displacement of the rotating shaft 23 in the counterclockwise direction after the motor mover 2 completes all the motion within one signal cycle. The first-order motion of the piezoelectric motor has a maximum no-load speed of 2.4 rad / s and a maximum output torque of 27.8 N·mm. When the input sinusoidal electrical signal voltage with a second-order resonant frequency of 240 VP-P and a frequency of 900 Hz is 240 VP-P, when the motor mover 2 completes all the motion within one signal cycle, the rotating shaft 23 rotates counterclockwise by 0.004 rad. The piezoelectric motor has a second-order motion, a maximum no-load speed of 3.9 rad / s, and a maximum output torque of 15.1 N·mm.

[0007] Furthermore, each of the L-shaped lateral extensions is an upright rectangular slot, with one horizontal end of the slot open and the other end closed. A pair of oblong holes are parallel to each other on the bottom plate of the slot. The slot is fitted and locked at one longitudinal end of the central base block 224. The pre-tightening bolt 223 is inserted into the sealing plate of the slot through the pre-tightening spring 224 and connected to the central base block 224. Rotating the pre-tightening bolt 223 can adjust the lateral fixed position of the pre-tightening block on the central base block 224. The pre-tightening block and the central base block 224 are fixedly connected by tightening through the cooperation of a pair of bolts and a pair of waist-shaped holes.

[0008] Furthermore, a pair of limiting protrusions are correspondingly provided in the middle of the upper and lower ends of the central base block 224. When the slot is engaged and locked at one longitudinal end of the central base block 224, it is used to limit the longitudinal position of the slot in the central base block 224.

[0009] Furthermore, each of the longitudinal extensions of the L-shape is provided with a positioning boss on its outer side, which is used to position the end of the rectangular sheet when one end of the rectangular sheet is fixedly connected to the longitudinal extension of the L-shape.

[0010] Furthermore, the rectangular frame includes a cover plate 11 and a base plate 12. The cover plate 11 is a right-angle bent plate, and the two ends of the right-angle bent plate are fixedly connected to the two ends of the base plate 12.

[0011] Furthermore, the rectangular frame, the ring 13, each mass block, the central base block 224, and the rotating shaft 23 are all made of 45 steel; each of the substrates 212 and each preload block is made of 65Mn; the preload spring 224 is made of carbon spring steel; and each of the piezoelectric ceramic sheets is made of PAZ-4.

[0012] The beneficial technical effects of the present invention are as follows: (1) The present invention provides a symmetrical biased chord self-clamping inertial rotary piezoelectric motor, which consists of a motor stator and a motor mover. The rectangular frame of the motor stator and the rotating shaft of the motor mover are connected by a pair of bearings, so that the motor stator and the motor mover are connected by bearings and there is no large sliding friction when they rotate relative to each other. At the same time, the clamping state of the piezoelectric motor is achieved by the clamping foot pressing on the inner wall of the circular ring of the motor stator when the drive mechanism vibrates. The clamping force is static friction force, and there is no relative sliding between the two. Therefore, the problem of the traditional inertial impact motor having a short service life due to working by sliding friction force is solved.

[0013] (2) The present invention provides a symmetrical biased string self-clamping inertial rotary piezoelectric motor, which operates in a resonant state, with a sinusoidal signal as the driving signal. The control system is simple, and the piezoelectric motor can achieve good output performance and realize bidirectional movement in either counterclockwise or clockwise directions. Different motion modes of the piezoelectric motor can be excited by changing the frequency of the input electrical signal, thereby controlling its motion direction. When the input sinusoidal signal voltage is 240 VP-P and the frequency is 150 Hz, the piezoelectric motor performs first-order motion with a maximum no-load speed of 2.4 rad / s and a maximum output torque of 27.8 N·mm. When the input sinusoidal signal voltage is 240 VP-P and the frequency is 900 Hz, the piezoelectric motor performs second-order motion with a maximum no-load speed of 3.9 rad / s and a maximum output torque of 15.1 N·mm.

[0014] (3) The present invention provides a symmetrical offset chord self-clamping inertial rotary piezoelectric motor, wherein a rectangular frame is arranged vertically, and a circular ring is horizontally fixed to the middle of the lower frame plate of the rectangular frame through a pair of arc-shaped grooves; a central base block is arranged on the lower frame plate corresponding to the center of the circular ring, and a rotating shaft is vertically inserted through the central axis of the central base block and fixed; a pair of pre-tightening blocks are arranged at the longitudinal ends of the central base block; a pair of base plates of a pair of drive mechanisms are arranged at the longitudinal ends of the central base block and are respectively located at the symmetrical offset chord position of the circular ring; a pair of clamping feet of a pair of drive mechanisms are arranged in a centrally symmetrical manner, and the center of symmetry is the center of the circular ring; therefore, the piezoelectric motor of the present invention has a centrally symmetrical structure design, and will not produce dynamic imbalance problems during operation, and has good running stability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to the present invention.

[0016] Figure 2 This is a schematic diagram of the motor stator of the present invention.

[0017] Figure 3 This is a schematic diagram of the motor actuator of the present invention.

[0018] Figure 4 This is a schematic diagram of the drive mechanism of the present invention.

[0019] Figure 5 This is a schematic diagram of the pre-tightening mechanism of the present invention.

[0020] Figure 6 This is a schematic diagram of the first-order motion principle of the piezoelectric motor of the present invention.

[0021] Figure 7 This is a schematic diagram of the second-order motion principle of the piezoelectric motor of the present invention.

[0022] The numbers in the diagram above are: motor stator 1, motor mover 2, cover plate 11, base plate 12, ring 13, a pair of bearings 14, a pair of drive mechanisms 21, preload mechanism 22, rotating shaft 23, a pair of mass blocks 211, substrate 212, a pair of piezoelectric ceramic sheets 213, a pair of preload blocks 221, preload spring 222, preload bolt 223, center base block 224, and clamping foot 2121. Detailed Implementation

[0023] 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

[0024] See Figure 1 A symmetrical biased string self-clamping inertial rotary piezoelectric motor includes a motor stator 1 and a motor mover 2. See Figure 2 The motor stator 1 includes a rectangular frame and a circular ring 13. The rectangular frame is arranged vertically, and the circular ring 13 is horizontally fixed to the middle of the lower frame plate of the rectangular frame through a pair of arc-shaped grooves. The rectangular frame includes a cover plate 11 and a bottom plate 12. The cover plate 11 is a right-angle bent plate, and the two ends of the right-angle bent plate are correspondingly fixedly connected to the two ends of the bottom plate 12.

[0025] See Figure 3 The motor actuator 2 includes a preload mechanism 22, a rotating shaft 23, and a pair of drive mechanisms 21. See Figure 5 The pre-tightening mechanism 22 includes a central base block 224 and a pair of pre-tightening blocks 221. The central base block 224 is arranged on the lower frame plate corresponding to the center of the ring 13. The rotating shaft 23 vertically passes through the central axis of the central base block 224 and is fixed. The upper and lower ends of the rotating shaft 23 are rotatably connected to the upper and lower frame plates of the rectangular frame through a pair of bearings 14. Each preload block is in the shape of an inverted L-shape, and the right-angle connection part of the L-shape is provided with a single-axis symmetrical straight-circular flexible hinge. The lateral extension plate of the L-shape is engaged with the central base block 224 through a slot and fixed by the preload bolt 223, so that the longitudinal extension plate of the L-shape is located at the offset chord position of the ring 13. Each L-shaped lateral extension is an upright rectangular slot, with one horizontal end open and the other end closed. A pair of oblong holes are parallel to each other on the bottom plate of the slot. The slot is fitted and locked at one longitudinal end of the central base block 224. The pre-tightening bolt 223 is inserted into the sealing plate of the slot through the pre-tightening spring 224 and connected to the central base block 224. Rotating the pre-tightening bolt 223 can adjust the lateral fixed position of the pre-tightening block on the central base block 224. The pre-tightening block and the central base block 224 are fixedly connected by tightening through the cooperation of a pair of bolts and a pair of waist-shaped holes.

[0026] A pair of limiting protrusions are provided at the middle of the upper and lower ends of the central base block 224. When the slot is engaged and locked at one of the longitudinal ends of the central base block 224, it is used to limit the longitudinal position of the slot in the central base block 224.

[0027] Each of the longitudinal extensions of the L-shape has a positioning boss on its outer side, which is used to position the end of the rectangular sheet when one end of the rectangular sheet is fixedly connected to the longitudinal extension of the L-shape.

[0028] See Figure 4 Each drive mechanism includes a substrate 212 and a pair of piezoelectric ceramic sheets 213. The substrate 212 is an upright, elongated rectangular sheet. One end of the rectangular sheet is fixedly connected to the L-shaped longitudinal extension of the pre-tightening block. The length direction of the rectangular sheet is parallel to the longitudinal direction of the central base block 224, so that the pair of substrates of the drive mechanism 21 are arranged at the longitudinal ends of the central base block 224 and are respectively located at the symmetrical offset chord position of the annulus 13. A pair of mass blocks 211 are provided on both sides of the other end of the rectangular sheet, and a clamping foot 2121 is provided on the lower end of the rectangular sheet in contact with the inner wall of the ring 13, so that the pair of clamping feet of the pair of driving mechanisms 21 are arranged in a centrally symmetrical manner, and the center of symmetry is the center of the ring 13. The pair of piezoelectric ceramic sheets 213 are respectively attached to the two sides of the substrate 212 between the clamping foot 2121 and the pair of mass blocks 211; When the pre-tightening bolt 223 is rotated, the lateral fixed position of the pre-tightening block on the central base block 224 can be adjusted, so that the base plate 212 deviates from or approaches the diameter of the ring 13, thereby adjusting the contact pre-tightening force between the clamping foot 2121 and the ring 13. Each pair of piezoelectric ceramic sheets 213 is symmetrically attached to the surface of the corresponding substrate 212, and the negative terminals are all connected to the substrate 212. During operation, the negative terminal of the power supply is connected to each substrate 212, and the positive terminal of the power supply is connected to the outer surface of each pair of piezoelectric ceramic sheets 213. This allows a pair of piezoelectric ceramic sheets 213 to be connected in parallel to the positive terminal of the power supply. When a sinusoidal electrical signal with a first-order resonant frequency is input, each pair of piezoelectric ceramic sheets 213 is excited and drives the substrate 212 to perform a first-order vibration. The motor mover 2 completes all the movements within one signal cycle, realizing that the rotating shaft 23 rotates a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the continuous counterclockwise rotation of the motor. When a sinusoidal electrical signal with a second-order resonant frequency is input, each pair of piezoelectric ceramic sheets 213 is excited, causing the substrate 212 to vibrate in a second order. The motor mover 2 completes all the motion within one signal cycle, realizing that the rotating shaft 23 rotates a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the motor to rotate continuously clockwise.

[0029] The rectangular frame, the ring 13, each mass block, the central base block 224, and the rotating shaft 23 are all made of 45 steel; each of the substrates 212 and each preload block is made of 65Mn; the preload spring 224 is made of carbon spring steel; and each of the piezoelectric ceramic sheets is made of PAZ-4.

[0030] See Figure 6 This is a first-order motion principle diagram of the piezoelectric motor of the present invention.

[0031] A sinusoidal electrical signal with a first-order resonant frequency is input to each pair of piezoelectric ceramic sheets 213, and each pair of piezoelectric ceramic sheets 213 is excited to drive the corresponding substrate 212 to perform first-order vibration.

[0032] At time t0~t1, the excitation signal voltage gradually rises from zero to the amplitude, and each drive mechanism deflects clockwise. During this process, the clamping foot 2121 presses the ring 13, the piezoelectric motor is in the clamping state, and the motor mover 2 cannot rotate. At times t1~t2, the excitation signal voltage gradually decreases from its amplitude to zero, and each drive mechanism rotates counterclockwise. During this process, the clamping foot 2121 still presses against the ring 13, the piezoelectric motor is in a clamping state, and the motor mover 2 cannot rotate. At times t2~t3, the excitation signal voltage gradually increases from zero to the inverted amplitude, each drive mechanism deflects counterclockwise, the clamping foot 2121 begins to disengage from the ring 13, the piezoelectric motor is in the released state, and the mass block has gained a certain kinetic energy at time t2, so under the action of inertia and excitation signal, the motor mover 2 begins to rotate counterclockwise. At times t3~t4, the excitation signal voltage gradually decreases from the inverted amplitude to zero, and each drive mechanism rotates clockwise. During this process, the clamping foot 2121 is still disengaged from the ring 13, the piezoelectric motor is in the released state, and the motor mover 2 still moves counterclockwise under the action of inertia. By time t4, the motor mover 2 has completed all the motion within one signal cycle. After one motion cycle, it has rotated a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the continuous counterclockwise rotation of the piezoelectric motor.

[0033] When the input sinusoidal signal voltage is 240 VP-P and the frequency is 150 Hz, when the motor mover 2 completes all the motion within one signal cycle, the rotating shaft 23 rotates counterclockwise by 0.016 rad, the piezoelectric motor's first-order motion has a maximum no-load speed of 2.4 rad / s and a maximum output torque of 27.8 N·mm.

[0034] See Figure 7 This describes the second-order motion principle of the piezoelectric motor of the present invention. A sinusoidal electrical signal with a second-order resonant frequency is input to each pair of piezoelectric ceramic plates 213, and the piezoelectric ceramic plates 213 are excited to drive the substrate 212 to perform second-order vibration.

[0035] At time t0~t1, the excitation signal voltage gradually rises from zero to the amplitude, and the end of each drive mechanism deflects counterclockwise. During this process, the clamping foot 2121 presses the ring 13 clockwise, the piezoelectric motor is in the clamping state, and the motor mover 2 cannot rotate. At times t1~t2, the excitation signal voltage gradually decreases from its amplitude to zero, and the end of each drive mechanism rotates clockwise. During this process, the clamping foot 2121 still presses against the ring 13, the piezoelectric motor is in a clamping state, and the motor mover 2 cannot rotate. At times t2~t3, the excitation signal voltage gradually increases from zero to the inverted amplitude, the end of each drive mechanism deflects clockwise, the clamping foot 2121 deflects counterclockwise and disengages from the ring 13, the piezoelectric motor is in the released state, and the mass block has gained a certain kinetic energy at t2, so under the action of inertia and excitation signal, the motor mover 2 begins to rotate clockwise. At times t3~t4, the excitation signal voltage gradually decreases from the inverted amplitude to zero, and each drive mechanism rotates counterclockwise. During this process, the clamping foot 2121 is still in the counterclockwise deflection position, disengaging from the ring 13. The piezoelectric motor is in the released state, and under the action of inertia, the motor mover 2 still moves clockwise. By time t4, the motor mover 2 has completed all the motion within one signal cycle. After one motion cycle, it has rotated a small angular displacement clockwise. The cyclic excitation signal can realize the continuous clockwise rotation of the piezoelectric motor.

[0036] When the input sinusoidal signal voltage is 240 VP-P and the frequency is 900 Hz, when the motor mover 2 completes all the motion within one signal cycle, the rotating shaft 23 rotates counterclockwise by 0.004 rad, the piezoelectric motor achieves second-order motion, the maximum no-load speed is 3.9 rad / s, and the maximum output torque is 15.1 N·mm.

[0037] 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 symmetrically biased chord self-clamping inertial rotary piezoelectric motor, characterized in that: It includes a motor stator (1) and a motor mover (2); The motor stator (1) includes a rectangular frame and a circular ring (13). The rectangular frame is arranged vertically, and the circular ring (13) is horizontally fixed to the middle of the lower frame plate of the rectangular frame through a pair of arc-shaped grooves. The motor mover (2) includes a preload mechanism (22), a rotating shaft (23), and a pair of drive mechanisms (21). The pre-tightening mechanism (22) includes a central base block (224) and a pair of pre-tightening blocks (221). The central base block (224) is arranged on the lower frame plate corresponding to the center of the ring (13). The rotating shaft (23) passes vertically through the central axis of the central base block (224) and is fixed. The upper and lower ends of the rotating shaft (23) are rotatably connected to the upper and lower frame plates of the rectangular frame through a pair of bearings (14). Each preload block is in the shape of an inverted L-shape, and the right-angle connection part of the L-shape is provided with a single-axis symmetrical straight-circular flexible hinge. The lateral extension plate of the L-shape is engaged with the central base block (224) through a slot and fixed by the preload bolt (223), so that the longitudinal extension plate of the L-shape is located at the offset chord position of the ring (13). Each drive mechanism includes a substrate (212) and a pair of piezoelectric ceramic sheets (213). The substrate (212) is an upright, long rectangular sheet. One end of the rectangular sheet is fixedly connected to the longitudinal extension of the L-shaped preload block. The length direction of the rectangular sheet is parallel to the longitudinal direction of the central base block (224), so that the pair of substrates of the drive mechanism (21) are arranged at the longitudinal ends of the central base block (224) and are respectively located at the symmetrical offset chord position of the annulus (13). A pair of mass blocks (211) are provided on both sides of the other end of the rectangular sheet, and a clamping foot (2121) is provided on the lower end of the rectangular sheet in line with the inner wall of the ring (13), so that the pair of clamping feet of the pair of driving mechanisms (21) are arranged in a centrally symmetrical manner, and the center of symmetry is the center of the ring (13). The pair of piezoelectric ceramic sheets (213) are respectively attached to the two sides of the substrate (212) between the clamping feet (2121) and the pair of mass blocks (211); When the pre-tightening bolt (223) is rotated, the lateral fixed position of the pre-tightening block on the central base block (224) can be adjusted so that the base plate (212) deviates from or approaches the diameter of the ring (13), thereby adjusting the contact pre-tightening force between the clamping foot (2121) and the ring (13); During operation, each substrate (212) is connected to the negative terminal of the power supply, and each pair of piezoelectric ceramic sheets (213) is connected to the positive terminal of the power supply. When a sinusoidal electrical signal with a first-order resonant frequency is input, each pair of piezoelectric ceramic sheets (213) is excited and drives the substrate (212) to perform a first-order vibration. The motor mover (2) completes all the movements within one signal cycle, and the shaft (23) rotates a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the continuous counterclockwise rotation of the motor. When a sinusoidal electrical signal with a second-order resonant frequency is input, each pair of piezoelectric ceramic sheets (213) is excited and drives the substrate (212) to perform second-order vibration. The motor mover (2) completes all the motion within one signal cycle, and the shaft (23) rotates a small angular displacement in the counterclockwise direction. The cyclic excitation signal can realize the motor to rotate continuously clockwise.

2. The symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to claim 1, characterized in that: When the input sinusoidal electrical signal voltage of the first resonant frequency of the piezoelectric motor is 240 VP-P and the frequency is 150 Hz, when the motor mover (2) completes all the motion within one signal cycle, the rotating shaft (23) rotates 0.016 rad in the counterclockwise direction. The first-order motion of the piezoelectric motor has a maximum no-load speed of 2.4 rad / s and a maximum output torque of 27.8 N·mm. When the input second-order resonant frequency sinusoidal electrical signal voltage is 240 VP-P and the frequency is 900 Hz, when the motor mover (2) completes all the motion within one signal cycle, the rotating shaft (23) rotates 0.004 rad in the counterclockwise direction, the piezoelectric motor performs second-order motion, the maximum no-load speed is 3.9 rad / s, and the maximum output torque is 15.1 N·mm.

3. The symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to claim 1, characterized in that: Each L-shaped lateral extension is an upright rectangular slot, with one horizontal end open and the other end closed. A pair of oblong holes are parallel to each other on the bottom plate of the slot. The slot is fitted and locked at one longitudinal end of the central base block (224). The pre-tightening bolt (223) is inserted into the sealing plate of the slot through the pre-tightening spring and connected to the central base block (224). Rotating the pre-tightening bolt (223) can adjust the lateral fixed position of the pre-tightening block on the central base block (224). The pre-tightening block and the central base block (224) are fixedly connected by tightening a pair of bolts and a pair of waist-shaped holes.

4. The symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to claim 3, characterized in that: The upper and lower ends of the central base block (224) are provided with a pair of limiting protrusions. When the slot is engaged with the longitudinal end of the central base block (224), it is used to limit the longitudinal connection position between the slot and the central base block (224).

5. A symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to claim 1, characterized in that: Each of the longitudinal extensions of the L-shape has a positioning boss on its outer side, which is used to position the end of the rectangular sheet when one end of the rectangular sheet is fixedly connected to the longitudinal extension of the L-shape.

6. A symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to claim 1, characterized in that: The rectangular frame includes a cover plate (11) and a bottom plate (12). The cover plate (11) is a right-angle bent plate, and the two ends of the right-angle bent plate are fixedly connected to the two ends of the bottom plate (12).

7. A symmetrically biased chord self-clamping inertial rotary piezoelectric motor according to claim 1, characterized in that: The rectangular frame, the ring (13), each mass block, the central base block (224), and the rotating shaft (23) are all made of 45 steel; each of the substrates (212) and each preload block is made of 65Mn; the preload spring is made of carbon spring steel; and each of the piezoelectric ceramic sheets is made of PAZ-4.

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