Low-frequency micro-stepping motor driven based on inverse piezoelectric effect
By utilizing the elliptical motion and resonant amplification effect of the spring, the working frequency of the inverse piezoelectric motor is reduced to below 1000Hz, which solves the wear and heating problems caused by high-frequency vibration, improves the service life and reliability of the motor, and is suitable for low-frequency fields. Application.
Patent Information
- Application Number
- CN202411276970.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2024-12-13
AI Technical Summary
The existing motors based on the inverse piezoelectric effect have high operating frequency, resulting in severe friction and wear, short life, low reliability, and high-frequency vibrations lead to heat generation, limiting their application in the low-frequency field.
Using the elliptical motion characteristics and resonant amplification effect of the spring, the excitation frequency of the piezoelectric ceramic is reduced to below 1000Hz, and the design of a low-frequency micro-induction motor is realized through the spring system, and the natural frequency of the spring is used to match the vibration frequency of the piezoelectric ceramic to reduce friction. Wear and heat.
It significantly improves the service life and reliability of the motor, reduces the heating power, extends continuous working time, and improves the application capabilities in the low-frequency field.
Smart Images
Figure CN119134959A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of micro-advanced motors, and relates to a micro-advanced motor based on the inverse piezoelectric effect, and specifically to a low-frequency micro-advanced motor driven based on the inverse piezoelectric effect. Background Art
[0002] The motor based on the inverse piezoelectric effect has some advantages that the electromagnetically driven motor does not have. Specifically, the structure is simple, no coils and magnets are required, and the structure can be made smaller, lighter, and thinner, even as small as 1 mm; the minimum rotation step unit is small, and the angle of a single step rotation can be as small as 0.001°, which can achieve precision control in high-precision applications; the inertia error is small, driven by friction, the mass of the moving body is light, the inertia is small, the response speed is fast, and the start and stop time is in the order of milliseconds; there is no electromagnetic induction effect, so it is not affected by electromagnetic induction. At the same time, it does not generate electromagnetic interference to the outside world, and is particularly suitable for working environments with strong magnetic fields such as nuclear magnetic equipment or space, as well as environments with magnetic field restrictions such as humanoid robots. At present, the most mature motor based on the inverse piezoelectric effect is the ultrasonic motor, which uses the inverse piezoelectric effect and ultrasonic vibration of piezoelectric ceramics to convert the microscopic deformation of the material into the macroscopic movement of the rotor through mechanical vibration and friction coupling. The operating frequency of the ultrasonic motor is in the ultrasonic frequency range, that is, above 20kHz.
[0003] Ultrasonic motors have been widely used in camera autofocus, watches, cars, robots and other fields due to their advantages such as small size, light weight, micro-adjustability and non-magnetism. However, ultrasonic motors also have shortcomings that need to be overcome, such as short life. The high-frequency friction transmission of ultrasonic motors causes extremely high wear on the friction surfaces, resulting in a short high-precision service life, generally not exceeding 1,000 hours; low reliability. As the use time increases, the material undergoes plastic deformation, and the pressure between the stator and rotor changes, resulting in a decrease in the reliability of the motor's working accuracy; short continuous working time, high-frequency friction causes the temperature between the moving and static rotors to rise, and too long working time will cause the motor temperature to be too high, which will have a temperature field effect on the motor itself and the surrounding environment. For most work occasions, the starting point for the application of ultrasonic motors is to use their non-magnetic and micro-adjustable properties, and the weight and volume requirements are not high. For such use occasions, the service life and continuous use time can be increased by reducing the frequency of the ultrasonic motor.
[0004] The purpose of improving service life and reliability by reducing the working frequency can be achieved with the help of the elliptical motion characteristics of the spring. The spring has an elliptical motion characteristic during compression and reset, that is, when the spring is compressed, for a right-handed spring, there is an upward, counterclockwise force on the upper compression surface during compression, and a downward, clockwise force on the upper surface during reset; for a left-handed spring, there is an upward, clockwise force on the upper surface during compression, and a downward, counterclockwise force on the upper surface during reset. If there is no rigid connection between the spring and the upper compression surface, then when the spring is reset, it has no force on the upper surface (because the spring has a downward movement tendency), which will cause the spring to have a rotational force on the compression surface when it moves upward during the reciprocating vibration of the spring; and when the spring is reset downward, there is no opposite rotational force, so that the compression surface in contact with the spring can be kept in unidirectional rotation. At the same time, by designing the natural frequency of the spring to be near the vibration frequency of the piezoelectric ceramic, the small deformation of the piezoelectric ceramic can be amplified through the resonance of the spring system, which can further reduce the size of the system and improve the reliability of the system.
[0005] Based on this, by utilizing the elliptical motion effect and resonance amplification effect of the spring, efficient amplification drive of the compression surface in contact with its end face can be achieved, and the excitation frequency of the piezoelectric ceramic can be reduced to a low-frequency range, such as below 1000Hz, to achieve the technical realization of a low-frequency micro-advance motor and solve the problem of limited service life and reliability of motors based on the inverse piezoelectric effect. Summary of the invention
[0006] Due to its unique advantages, the inverse piezoelectric motor can be used in aerospace, aviation, robotics, clocks and other fields that require precise adjustment and no magnetic field interference. However, the existing inverse piezoelectric motor operates at an ultrasonic frequency, i.e. 20kHz, and has problems such as wear and heat caused by high-frequency vibration friction, which seriously affect the life, reliability and continuous working ability of the application. In order to solve the above problems and improve the engineering application reliability of the inverse piezoelectric motor, a spring is combined with the inverse piezoelectric motor. The resonance characteristics of the spring are used to reduce the frequency to below 1000Hz while maintaining the motor efficiency, thereby achieving the purpose of increasing the service life by 20 times and reducing the heat generation power by 95%.
[0007] In order to achieve the above object, the present invention adopts the following technical solutions:
[0008] A low-frequency micro-advance motor driven by the inverse piezoelectric effect, characterized in that it includes a base, a ceramic laminate, a spring, a friction plate, a thrust bearing, an output shaft, a support bearing, a bearing cover, a tension sleeve, a preload spring, and a preload nut. The base, ceramic laminate, friction plate, bearing cover, and tension sleeve are annular rotating bodies, and the base, ceramic laminate, spring, friction plate, bearing cover, and tension sleeve are all coaxial with the output shaft; the base includes a mounting surface adjacent to the ceramic laminate and a mounting cavity opposite to the mounting surface, and the mounting cavity has step one, step two, and step three; the tension sleeve includes a tension flange, a hollow rod, a hollow through cavity, and an external thread at the end of the hollow rod; the ceramic laminate is placed on the mounting surface, and the spring is placed on the ceramic laminate; the tension sleeve is installed from the inner cavity of the spring so that the tension flange is pressed on the lowermost part of the spring, and the hollow rod passes through the ceramic laminate and the base and falls into the mounting cavity; the preload spring is sleeved on the outside of the hollow rod and along the axial direction of the hollow rod The preload nut is screwed into the external thread to preload the preload spring, thereby compressing the base, ceramic laminate and spring. The friction plate is fixed to the upper end surface of the spring by screws, and the thrust bearing is placed on the friction plate. The lower base of the thrust bearing contacts the friction plate, and a preload force F is applied to the upper base to fix the thrust bearing, the friction plate and the spring together. The output shaft is inserted from the center of the thrust bearing and passes through the hollow through-hole of the tension sleeve. The output shaft is fixed to the lower base of the thrust bearing, and there is a clearance fit between the output shaft and the upper base, so that the output shaft can rotate relatively freely. The lower end of the output shaft is connected to the support bearing, and the support bearing is clamped on the second step through the bearing pressure cover, and the bearing pressure cover is clamped on the first step. The ceramic laminate undergoes alternating vibration under the action of the alternating electric field, and the vibration acts on the spring to cause the upper end in contact with the friction plate to undergo elliptical alternating reciprocating motion, thereby driving the lower base of the thrust bearing and the output shaft connected thereto to rotate slightly through the friction plate.
[0009] The micro-advanced motor uses the center plane between the upper end surface and the lower end surface of the base as the mirror plane, and mirror-arranges two groups of ceramic laminates, springs, friction plates, and thrust bearings to form two micro-advanced motor systems. The two systems share an output shaft, and the output shaft forms two output ends, output end 1 and output end 2, on the two systems respectively; the two systems are preloaded by preload forces F1 and F2.
[0010] The thrust bearing may also be a radial bearing, the inner ring seat of the radial bearing being connected to the friction plate and the output shaft.
[0011] The operating frequency of the micro-motor is 10-500 Hz.
[0012] Compared with the prior art, the present invention has the following advantages: (1) The present invention provides a new micro-advance motor based on the inverse piezoelectric effect, which makes up for the lack of low-frequency application of ultrasonic motors; (2) The present invention adopts the amplification effect of the spring to reduce the operating frequency of the motor from the ultrasonic band to below 500 Hz, greatly reducing wear and heat generation, and increasing the service life and continuous working time of the motor; (3) It provides a new method for micro-advance operation in non-magnetic environment in the low-frequency field. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a cross-sectional view of the micro-motor of the present invention.
[0014] Figure 2 Schematic diagram of the base
[0015] Figure 3 This is a schematic diagram of the tension sleeve.
[0016] Figure 4 Schematic diagram of a dual output shaft micro-advanced motor. DETAILED DESCRIPTION
[0017] The present invention will be further described below in conjunction with the accompanying drawings.
[0018] Figure 1 The figure shows a cross-sectional view of a low-frequency micro-advanced motor driven by the inverse piezoelectric effect, including a base 1, a ceramic laminate 2, a spring 3, a friction plate 4, a thrust bearing 5, an output shaft 6, a support bearing 7, a bearing cover 8, a tensioning sleeve 9, a preload spring 10, and a preload nut 11, wherein the base 1, the ceramic laminate 2, the friction plate 4, the bearing cover 8, and the tensioning sleeve 9 are annular rotating bodies, and the base 1, the ceramic laminate 2, the spring 3, the friction plate 4, the bearing cover 8, and the tensioning sleeve 9 are all coaxial with the output shaft 6.
[0019] like Figure 2 As shown, the base 1 includes a mounting surface 101 adjacent to the ceramic laminate 2 and a mounting cavity 102 opposite to the mounting surface 101. The mounting cavity 102 has a step 103, a step 2 104, and a step 3 105. The installation cavity is mainly provided to facilitate fixing the base 1, the ceramic laminate 2, and the spring 3 together, and to support the output shaft 6. Figure 3In the embodiment, the tensioning sleeve 9 includes a tensioning flange 91, a hollow rod 92, a hollow through cavity 93, and an external thread 94 at the end of the hollow rod 92; the ceramic laminate 2 is placed on the mounting surface 101. Generally, a groove for placing the spring is provided on the mounting surface 101, and the spring 3 is placed on the ceramic laminate 2; the tensioning sleeve 9 is installed from the inner cavity of the spring 3, so that the tensioning flange 91 is pressed on the lowermost part of the spring 3, and the hollow rod 92 passes through the ceramic laminate 2 and the base 1 and falls into the mounting cavity 102; the pre-tightening spring 10 is sleeved on the outside of the hollow rod 92 and is stuck on the step three 105 along the axial direction of the hollow rod 92; the pre-tightening nut 11 is screwed into the external thread 94 to pre-tighten the pre-tightening spring 10, thereby compressing the base 1, the ceramic laminate 2, and the spring 3; the friction plate 4 is fixed to the upper end surface of the spring 3 by screws, and the thrust bearing 5 is placed on the friction plate 4. The lower base 51 of the thrust bearing 5 contacts the friction plate 4, and a preload force F is applied to the upper base 52, so that the thrust bearing 5, the friction plate 4, and the spring 3 are fixed together; the output shaft 6 is inserted from the center of the thrust bearing 5 and passes through the hollow through cavity 93 of the tension sleeve 9. The output shaft 6 is fixed to the lower base 51 of the thrust bearing 5, and there is a clearance fit between the output shaft 6 and the upper base (52), so that the output shaft 6 can rotate freely relative to the lower base 51 of the thrust bearing 5; the lower end of the output shaft 6 is connected to the support bearing 7, and the support bearing 7 is clamped on the second step 104 through the bearing pressure cover 8, and the bearing pressure cover 8 is clamped on the first step 103; the ceramic laminate 2 undergoes alternating vibration under the action of the alternating electric field, and the vibration acts on the spring 3 to make the upper end in contact with the friction plate 4 undergo elliptical alternating reciprocating motion, and then drives the lower base 51 of the thrust bearing 5 and the output shaft 6 connected thereto to rotate slightly through the friction plate 4. If necessary, a non-return mechanism such as a ratchet can be set on the output shaft 6.
[0020] like Figure 4 As shown, the micro-advanced motor can also have the center plane between the upper end face and the lower end face of the base 1 as a mirror plane, and two sets of ceramic laminates 2, springs 3, friction plates 4, and thrust bearings 5 are mirror-arranged to form two micro-advanced motor systems. The two systems share an output shaft 6, and the output shaft 6 forms two output ends, output end 1 61 and output end 2 62, on the two systems respectively; the two systems are preloaded by preload forces F1 and F2.
[0021] The thrust bearing 5 may also be a radial bearing, the inner ring seat of the radial bearing being connected to the friction plate 4 and the output shaft 6 .
[0022] Based on the modal response characteristics of the spring, the operating frequency of a general micro-motor is 10-500Hz.
[0023] Example 1
[0024] The design frequency of the low-frequency micro-advance motor in this embodiment is 10Hz, the base is made of aluminum alloy, the number of ceramic laminates is 4, the spring is an aluminum alloy integrally formed spring, the spring has good anti-deflection performance and the designed natural frequency is 10Hz, and the friction plate is a composite ceramic plate. By applying an alternating voltage with a frequency of 10Hz to the ceramic laminate, the ceramic laminate drives the spring to reciprocate, and the upper friction plate in contact with the spring rotates clockwise (from the direction of the friction plate), and runs continuously for 12h. At the 1st hour, 3rd hour, 6th hour, 9th hour, and 12th hour, the speed and upper surface temperature of the friction plate are tested respectively (the test cycle is 20min, the speed value is the conversion value, and the temperature value is the average value of 5 points within 20min). The speed is 0.01rpm, and the upper surface temperature is 48℃, 49℃, 48℃, 49℃, and 50℃ respectively, indicating that the speed control is stable under low-frequency conditions without drastic temperature rise.
[0025] Example 2
[0026] The design frequency of the low-frequency micro-advance motor in this embodiment is 100Hz, the base is made of aluminum alloy, the number of ceramic laminates is 6, the spring is an aluminum alloy integrally formed spring, the spring has good anti-deflection performance and the designed natural frequency is 100Hz, and the friction plate is a composite ceramic plate. By applying an alternating voltage with a frequency of 100Hz to the ceramic laminate, the ceramic laminate drives the spring to reciprocate, and the upper friction plate in contact with the spring rotates clockwise (from the direction of the friction plate), and runs continuously for 12h. At the 1st hour, 3rd hour, 6th hour, 9th hour, and 12th hour, the speed and upper surface temperature of the friction plate are tested respectively (the test cycle is 20min, the speed value is the conversion value, and the temperature value is the average value of 5 points within 20min). The speed is 0.06rpm, and the upper surface temperature is 60℃, 62℃, 63℃, 63℃, and 64℃ respectively, indicating that the speed control is stable under low-frequency conditions without drastic temperature rise.
[0027] Example 3
[0028] The design frequency of the low-frequency micro-advance motor in this embodiment is 500Hz, the base is made of aluminum alloy, the number of ceramic laminates is 6, the spring is an aluminum alloy integrally formed spring, the spring has good anti-deflection performance and the designed natural frequency is 500Hz, and the friction plate is a composite ceramic plate. By applying an alternating voltage with a frequency of 500Hz to the ceramic laminate, the ceramic laminate drives the spring to reciprocate, and the upper friction plate in contact with the spring rotates clockwise (from the direction of the friction plate), and runs continuously for 12h. At the 1st hour, 3rd hour, 6th hour, 9th hour, and 12th hour, the speed and upper surface temperature of the friction plate are tested respectively (the test cycle is 20min, the speed value is the conversion value, and the temperature value is the average value of 5 points within 20min). The speed is 0.12rpm, and the upper surface temperature is 73℃, 75℃, 74℃, 75℃, and 75℃ respectively, indicating that the speed control is stable under low-frequency conditions without drastic temperature rise.
Claims
1. A low-frequency micro-motor driven by the inverse piezoelectric effect, characterized in that: The invention comprises a base (1), a ceramic laminate (2), a spring (3), a friction plate (4), a thrust bearing (5), an output shaft (6), a support bearing (7), a bearing cover (8), a tension sleeve (9), a preload spring (10), and a preload nut (11); the base (1), the ceramic laminate (2), the friction plate (4), the bearing cover (8), and the tension sleeve (9) are annular rotating bodies, and the base (1), the ceramic laminate (2), the spring (3), the friction plate (4), the bearing cover (8), and the tension sleeve (9) are all coaxial with the output shaft (6); the base (1) comprises a mounting surface (101) adjacent to the ceramic laminate (2) and a mounting cavity (101) opposite to the mounting surface (101). 2), the installation cavity (102) has step one (103), step two (104), and step three (105); the tension sleeve (9) includes a tension flange (91), a hollow rod (92), a hollow through cavity (93), and an external thread (94) at the end of the hollow rod (92); the ceramic laminate (2) is placed on the installation surface (101), and the spring (3) is placed on the ceramic laminate (2); the tension sleeve (9) is installed from the inner cavity of the spring (3), so that the tension flange (91) is pressed against the lower part of the spring (3), and the hollow rod (92) passes through the ceramic laminate (2) and the base (1) and falls into the installation cavity (102); the preload spring (10) is sleeved on the outside of the hollow rod (92) The preload nut (11) is screwed into the external thread (94) to preload the preload spring (10), thereby pressing the base (1), the ceramic laminate (2), and the spring (3); the friction plate (4) is fixed to the upper end surface of the spring (3) by screws, and the thrust bearing (5) is placed on the friction plate (4). The lower base (51) of the thrust bearing (5) contacts the friction plate (4), and a preload force F is applied to the upper base (52) to fix the thrust bearing (5), the friction plate (4), and the spring (3) together; the output shaft (6) is inserted from the center of the thrust bearing (5) and inserted from the hollow through cavity (91) of the tension sleeve (9). 3) passes through, the output shaft (6) is fixed to the lower base (51) of the thrust bearing (5), and is clearance-matched with the upper base (52) so as to be relatively free to rotate; the lower end of the output shaft (6) is connected to the support bearing (7), the support bearing (7) is clamped on the second step (104) through the bearing pressure cover (8), and the bearing pressure cover (8) is clamped on the first step (103); the ceramic laminate (2) undergoes alternating vibration under the action of the alternating electric field, and the vibration acts on the spring (3) to cause the upper end thereof in contact with the friction plate (4) to undergo elliptical alternating reciprocating motion, thereby driving the lower base (51) of the thrust bearing (5) and the output shaft (6) connected thereto to undergo micro-rotation through the friction plate (4).
2. A low-frequency micro-motor driven by the inverse piezoelectric effect according to claim 1, characterized in that: The micro-advanced motor uses the center plane between the upper end surface and the lower end surface of the base (1) as a mirror plane, and mirror-arranges two groups of ceramic laminates (2), springs (3), friction plates (4), and thrust bearings (5) to form two micro-advanced motor systems. The two systems share an output shaft (6), and the output shaft (6) forms two output ends, output end 1 (61) and output end 2 (62), on the two systems respectively; the two systems are preloaded by preload forces F1 and F2.
3. A low-frequency micro-motor driven by the inverse piezoelectric effect according to claim 2, characterized in that: The thrust bearing (5) may also be a radial bearing, the inner ring seat of the radial bearing being connected to the friction plate (4) and the output shaft (6).
4. A low-frequency micro-motor driven by the inverse piezoelectric effect according to claim 1, characterized in that: The operating frequency of the micro-motor is 10-500 Hz.