21世纪超声电机技术展望

首先回顾了超声电机技术在２０世纪国内外发展的情况,叙述了南京航空航天大学超声电机研究中心在超声电机研究方面的进展,其次预计了在２１世纪国内外市场对超声电机的需求,特别列举了超声电机技术将对我国国防和国民经济各部门起到的重大作用,最后论述了２１世纪超声电机技术的研究人员所面临的任务,针对我国在超声电机理论、实验和材料研究工作的现状,提出了２１世纪为发展我国超声电机技术急需解决的若干重要课题。     

直线超声电机的研究进展

文中概述了直线超声电机特点、类型、驱动原理及其在国内外的发展研究现状，展望了直线超声电机的应用前景。     

采用耦合机构驱动的压电电机的研究进展

给出了压电电机的定义，按驱动方式对压电电机进行了分类；介绍了耦合机构驱动的概念及从蠕动驱动到楔蠕动驱动再到离合器驱动的发展过程，指出离合器驱动方式与传统的摩擦驱动方式相比，优点在于消除了摩擦损耗和易于进行精确的位置控制等；介绍了两种采用离合器耦合驱动的压电旋转型电机；分析了电机在研制过程中的技术难点在于消除或减小离合器回程间隙及位移放大机构等，指出耦合机构驱动的旋转型压电电机是今后压电电机发展的一个重要方向。     

聚四氟乙烯基超声电机转子摩擦材料性能研究

制备聚苯酯、碳化硅微粉及玻璃纤维填充聚四氟乙烯基超声电机转子摩擦材料,研究填充剂对复合材料力学、摩擦学性能及超声电机机械特性的影响。结果表明:POB、玻璃纤维、碳化硅微粉均能提高PTFE复合材料的硬度、弹性模量和耐磨性。在本文研究的范围内,质量分数20%玻璃纤维填充的聚四氟乙烯复合材料具有较低的摩擦因数和磨损率,使用该复合材料时超声电机具有较低的堵转力矩和较高的空载转速,且运行稳定,噪声较低。     

聚苯酯填充聚四氟乙烯基超声电机转子摩擦材料性能研究

制备聚苯酯填充聚四氟乙烯基超声电机转子摩擦材料,探讨聚苯酯含量对聚四氟乙烯基摩擦材料力学和摩擦学性能以及对应超声电机性能的影响。结果表明:聚苯酯能够提高PTFE复合材料的硬度和弹性模量;随着聚苯酯含量的增加,复合材料的摩擦因数和磨损量均先减小后增大,在本文研究范围内,当聚苯脂质量分数为5%时,复合材料的摩擦因数最小,磨损量最低,且使用该复合材料时超声电机的堵转力矩和空载转速均较高,综合性能较优。     

超声电机在国外的发展

简要回顾了超声电机的发展，并简述其工作原理和结构形式，对其各种控制策略做了简要的比较。分析国外超声电机的关键问题及研究现状，探讨其在各领域中的应用前景及发展趋势。     

超声电机技术的发展和应用

回顾了超声电机的发展和应用情况,叙述了超声电机的特点,总结了超声电机的分类方法,指出了超声电机技术的发展趋势。针对我国超声电机技术开发和研究现状,提出了我国超声电机产业化进程中亟待解决的一些关键问题。     

直线型超声电机的发展及应用

概述了直线型超声电机的运动机理，综述了国内外直线型超声电机的发展及其研究现状，列举了一些典型例子，总结了直线型超声电机的应用领域。针对现在直线型超声电机在理论、实验、材料等方面存在的问题，指出了在其研究开发中需要解决的关键技术。     

玻璃纤维粉对聚合物基超声电机摩擦材料性能的影响

为获得硬度高、耐磨性好、满足超声电机低速大力矩运行要求的摩擦材料,采用冷压烧结法制备玻璃纤维粉改性聚合物基摩擦材料,研究玻璃纤维粉体积分数对摩擦材料力学性能、超声电机性能以及摩擦学性能的影响。结果表明:玻璃纤维粉可以增大摩擦材料的弹性模量和硬度,降低材料冲击韧性;摩擦材料的摩擦因数随玻璃纤维粉体积分数的增加有明显提升;玻璃纤维粉可以改善摩擦材料的超声电机性能和耐磨性,随着玻璃纤维粉体积分数的增加,摩擦材料的超声电机驱动性能先提高后下降,材料的磨损机制由黏着磨损向较为严重的疲劳磨损转变。在文中研究范围内,玻璃纤维粉体积分数为30%时改性摩擦材料具有最好的超声电机驱动性能和耐磨性。     

阶梯圆柱形压电振子直线型超声电机

针对现有直线型超声电机推力较小、效率不高的普遍现状,提出利用阶梯圆柱形压电振子驱动的直线型超声电机.其压电振子包含两组压电陶瓷单元,经逆压电效应激发阶梯形圆柱压电振子在两个正交方向上分别产生5阶弯曲振动,使振子两个圆盘形结构的表面质点形成椭圆运动,经摩擦作用于固定导轨,使振子组件沿导轨产生直线运动,进而构成直线型超声电机.采用有限元仿真方法确定结构尺寸,制作原理样机并进行了相关试验.原理样机获得如下性能:最大输出力为16.2 N;最大速度为180 mm/s;最大效率为38％;响应时间为24 ms;步进分辨率为2μm.     

新型惯性式直线超声压电电机的运动机理及实验研究

提出了一种新型惯性式直线超声压电电机.该电机利用压电晶体的逆压电效应和惯性位移原理,由定子的轴向变形,通过摩擦力的作用,以惯性位移的形式传递运动.它由两部分组成,定子由具有位移放大功能的压电复合换能器和轴组成,动子为一带有缺口和环形凹槽的环.分析了该电机的工作原理,并通过仿真和实验相结合的方法分析了两种激励方式对电机性能的影响.实验结果表明:样机采用方波驱动比采用锯齿波驱动的效果好;在采用方波驱动信号驱动时,样机的最大空载速度可达到11 mm/s,最大输出力达到0.5 N.     

三角位移转换式压电直线电机

为了在保持电机精度的同时获得较大作动行程,提出了一种以叠层压电陶瓷作为激励振动源的压电直线电机。分析了电机的工作原理,推导了电机驱动足在工作时的运动轨迹。设计安装了电机样机,并对其定子进行了测试。最后,在两种激发条件下实验研究了电机的整机性能。结果表明:单组叠层压电陶瓷激励时,该样机定子驱动头在接触面法向和切向同时具有振动分量,并能够在阶跃和连续两种不同激励方式下实现单向大行程直线运动。以锯齿波激励时可实现步进运动,激励频率为20Hz时步距为0.1μm;以两路相位差π/2的正弦波激励时,可在1.5kHz到5.8kHz的激励频率区间输出稳定连续的直线运动,其运动速度随激励频率的升高而增大,在峰-峰值110V(50V偏置)的正弦电压激励下其推力可达4.8N。该电机具有高位置分辨率和宽频率响应,可以在两种工作模式下分别稳定地实现直线步进和大行程连续运行。     

Novel linear piezoelectric motor for precision position stage

Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus 0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.     

单振子二自由度超声电机驱动电源

设计了用于平板形单振子二自由度超声电机的驱动电源,并针对驱动电源电流负荷较大,输出功率利用率不高的问题,提出了优化驱动性能的措施.该电源利用压控振荡器产生正弦小信号,经高压及功率放大后得到较高的驱动电压及较大的驱动电流实现电机驱动.根据压电振子等效电路模型及工作特性,采取与超声电机并联电感的方法优化了电源驱动性能.制作了驱动电源样机,并对输出性能及优化效果进行了测试.测试结果表明:设计的电源驱动电压及频率可独立连续调节,可输出理想的正弦信号波形;在49.127 kHz、49.756 kHz两种频率下,接超声电机负载时,最大输出电压分别为176.0 V及171.2 V;超声电机并联1.442 mH电感后,电源驱动电流可减少至原来的7.27％和7.41％,功率因数可提高至0.968和0.9550.得到的结果显示,设计的电源满足超声电机驱动要求,采取的优化措施在减小电源电流负荷及提高电源输出功率利用率方面效果明显.     

Principle and experimental verification of novel dual driving face rotary ultrasonic motor

Existing rotary ultrasonic motors operating in extreme environments cannot meet the requirements of good environmental adaptability and compact structure at same time,and existing ultrasonic motors with Langevin transducers show better environmental adaptability,but size of these motors are usually big due to the radial arrangement of the Langevin transducers.A novel dual driving face rotary ultrasonic motor is proposed,and its working principle is experimentally verified.The working principle of the novel ultrasonic motor is firstly proposed.The 5th in-plane flexural vibration travelling wave,excited by the Langevin transducers around the stator ring,is used to drive the rotors.Then the finite element method is used in the determination of dimensions of the prototype motor,and the confirmation of its working principle.After that,a laser Doppler vibrometer system is used for measuring the resonance frequency and vibration amplitude of the stator.At last,output characteristics of the prototype motor are measured,environmental adaptability is tested and performance for driving a metal ball is also investigated.At room temperature and 200 V(zero to peak) driving voltage,the motor’s no-load speed is 80 r/min,the stalling torque is 0.35 N·m and the maximum output power is 0.85 W.The response time of this motor is 0.96 ms at the room temperature,and it decreases or increases little in cold environment.A metal ball driven by the motor can rotate at 210 r/min with the driving voltage 300 V(zero to peak).Results indicate that the prototype motor has a large output torque and good environmental adaptability.A rotary ultrasonic motor owning compact structure and good environmental adaptability is proposed,and lays the foundations of ultrasonic motors’ applications in extreme environments.     

A test method to investigate the tribological behaviour of friction materials under ultrasonic fretting conditions

To investigate and understand the tribological behaviour of high-frequency tribosystems such as ultrasonic motors, a specific test method is necessary. This work reports on the construction of a test machine to evaluate the friction and wear behaviour of friction materials under ultrasonic fretting conditions, as well as giving some representative experimental results. Hard/soft (steel/polymer) and hard/hard (steel/alumina, alumina/alumina) couples were studied with respect to their application as contact materials in ultrasonic motors. Investigation of friction behaviour at high frequencies showed that friction-induced vibrations lead to friction forces of much lower magnitude than predicted by quasistationary friction coefficients obtained for sliding friction. The wear behaviour is characterised by abrasive, adhesive, fatigue and oxidative mechanisms, depending on the mating materials. For polymeric friction materials, the influence of fibre reinforcement and the incorporation of PTFE as a solid lubricant were evaluated. The presence of PTFE resulted in a strong improvement of both friction and wear behaviour.     

超声波马达的真空和温度特性研究

研究了超声波马达在非常状态下的驱动行为,选取了5种工程塑料作为转子摩擦材料,利用真空试验机和自制的与其相匹配的超声波马达模拟试验台,采用对比试验方法,研究了接触预紧力、真空度和环境温度等对行波型超声波马达的驱动特性的影响。结果表明,随着预紧力和真空度的增加,马达的堵转力矩增加而空载转速下降;随着环境温度的增加马达的空载转速下降。运用声学理论分析了真空度对接触状态的影响,得出声悬浮作用使定子和转子的动态接触力减小的结论。在真空状态下,超声波马达的堵转力矩比常态下提高的主要原因是声悬浮作用降低引起定子和转子的动态接触力增加所致。     

Si_3N_4陶瓷旋转超声磨削加工的表面摩擦特性

为了探索结构陶瓷材料在摩擦过程中表面形貌的变化规律及其对摩擦特性影响,分析了摩擦过程中材料的接触过程及力学关系,并对旋转超声磨削加工的Si3N4陶瓷试样开展了摩擦表面形貌、摩擦因数等特性的试验研究。首先根据接触特点和材料特性,基于分形理论推导出接触面总载荷计算公式,基于该公式建立了结构陶瓷摩擦因数分形模型。分析结果表明:当初始表面轮廓分形维数分别为1.4,1.45,1.5和1.55时,摩擦因数与摩擦后表面轮廓分形维数呈类似正态分布曲线。然后通过旋转超声磨削加工的Si3N4陶瓷试样面面接触摩擦试验,研究了摩擦后陶瓷材料表面微观形貌和摩擦因数变化规律,分析了各因素对摩擦因数的影响。试验结果表明:产生微观裂纹是Si3N4陶瓷摩擦后表面微观形貌的显著特点;温度值等于160℃是Si3N4陶瓷摩擦因数由下降转为上升的拐点;当施加载荷为360N和往复频率为80Hz时,摩擦因数最大。得到的结果为通过表面形貌控制提高结构陶瓷耐磨性能提供了技术支撑。