Development of ultrasonic motors--recent trends inChina

基于最新参考文献与INTERNET网络查询,本文提出超声马达或压电驱动器在我国科技领域最新的研究成果及其未来走向。其中,能够引起研究人员兴趣的尖端性领域包括超声马达的微型化;具有多个自由度的压电驱动器;具有新颖结构的压电驱动器;超声马达的振动实验测试;高分辨率的压电驱动器;超声马达的使用寿命;超声马达的动力学模型等。     

压电超声马达简介

近年来压电超声马达很引入注目．传统的马达是利用电磁力驱动的，而压电超声马达则是利用压电或电致伸缩材料作为驱动源，直接推动可运动的部件产生直线的或旋转的运动．本义重点介绍压电蠕动马达和超声行波马达的原理和简单结构．     

一种驻波型超声马达的研究

研制出一种以长条片关压电陶瓷振子作煊子的驻波型超声马达，该马达具有整体结构简单，易于制作与调整、驱动电路合理、运行稳定的特点；由实验研究，测出了其主要性能参数，利用该马达已开发出特性优异的超声步进马达及时钟模型，小型走纸机。     

超声振子箝位压电直线微动马达研究

本文提出一种利用环形三叠片超声振子箝位的压电直线微动马达.这种马达的箝位振子与导轴形成摩擦付。振子共振时其动摩擦系数与静摩擦系数之比降为～0.1。箝位振子的激励电压仅为±80V(峰峰值).马达速度为0—2mm/min;位移分辨率为50nm;驱动力约0.2kgf.这种马达还具有工艺简单的特点.     

直线微动马达箝位超声换能器(PGUT)研究

本文提出一种用于超声微动直线马达的环形三叠片压电箝位超声换能器(Position-Cripped Ultrasonic Transducer,简称:PGUT)。其原理是利用换能器的超声振动产生的表面效应,来实现直线微动马达的箝位或松位。本文给出了这种换能器的共振频率、有效机电耦合系数及实验结果。实验结果表明,PGUT 能迅速、平稳的执行箝位、松位动作,并且具有低工作电压驱动相似文献   

超声马达中夹紧压电环的非轴对称振动

应用环形压电板振子的超声马达具有厚度小的优点,能满足很多工程上的要求。其工作原理和其他类型的超声马达一样,也是通过摩擦力把振子表面质点的椭圆运动变换为转子的运动。因此,为要开发出性能优良的超声马达,必须清楚了解作为超声马达定子的环形板的振动特征。过去对环形板或圆盘的分析均仅考虑自由振动的情形,本文则分析了在环的内缘或外缘夹紧的情况下,环形压电板的非轴对称振动。内容包括振动时的位移分布图样,自由边缘上质点的椭圆运动,表面上感应电荷的分布及机电耦合因数等。还进行了数字计算,并从应用于超声马达的角度出发,对几种不同的振动模式作了评估。     

用于高功率激光装置的压电步进驱动器

根据神光Ⅱ高功率激光装置的具体工程需求,设计了一种以层叠式压电陶瓷为驱动元件的新型压电步进驱动器。驱动器利用杠杆机构实现箝位机构和进给机构交替箝位动子,通过对压电陶瓷小步距的位移连续累加的步进方式,实现大行程直线位移;具有控制简单、行程大、分辨力高及断电箝位的特点。样机试验结果表明,驱动器的运动分辨力达到nm级,步距分辨力达到50nm,行程21mm。     

高温压电材料、器件与应用

作为重要的功能材料,压电材料已经在国民经济的多个领域里有着重要应用.随着现代工业的快速发展,特别是新能源、交通和国防工业的高速发展,功能材料的应用已经从常规使用转向极端环境下的服役.本文综述了具有高居里点的压电材料,包括钙钛矿型压电陶瓷、铋层状结构氧化物压电陶瓷、钨青铜结构压电陶瓷以及非铁电压电单晶等;介绍了其晶体结构特征和高温压电性能、最新研究进展,并列举了一系列的高温压电器件和应用,包括高温压电探测器、传感器、换能器和驱动器等.另外,本文总结了高温压电材料的热点研究问题,并展望了今后的发展方向.     

高分辨特性压电行波旋转马达研究

本文对一种压电行波型旋转超声马达进行了理论与实验研究。采用有限元方法对行波马达驱动定子的各阶振动模式、谐振频率进行了分析；研制的行波马达具有以下特点：低转速（0－50r．p．m）、较大力矩输出（0~1．9kgf．cm）、自锁功能、高的角分辨率和定位精度（±0.15°）。     

板状行波马达简化电学模型的建立

提出一种利用具有等同振动特性的１／２波长马达定子来建立圆板型行波超声马达电学模型的方法，该方法结合马达定子复合板振动模式的特点，直接利用哈密顿原理对行波型马达定子的等效电路进行精确求解。模型反映了行波马达形成机理，同时计入了马达高阶非轴对称振动模式、齿的结构尺寸、压电陶瓷各向异性等要素。利用该方法可求解行波型马达在各阶常用振动模式下的静态电容、动态电容、动态电感、动态电阻、等效输入阻抗等电学参数，与实验测试达到了很好的一致性。     

Closed-form solution for free vibration of piezoelectric coupled annular plates using Levinson plate theory

Free vibration analysis of annular moderately thick plates integrated with piezoelectric layers is investigated in this study for different combinations of soft simply supported, hard simply supported and clamped boundary conditions at the inner and outer edges of the annular plate on the basis of the Levinson plate theory (LPT). The distribution of electric potential along the thickness direction in the piezoelectric layer is assumed as a sinusoidal function so that the Maxwell static electricity equation is approximately satisfied. The differential equations of motion are solved analytically for various boundary conditions of the plate. In this study the closed-form solution for characteristic equations, displacement components of the plate and electric potential are derived for the first time in the literature. To demonstrate the accuracy of the present solution, comparison studies is first carried out with the available data in the literature and then natural frequencies of the piezoelectric coupled annular plate are presented for different thickness-radius ratios, inner-outer radius ratios, thickness of piezoelectric, material of piezoelectric and boundary conditions. Present analytical model provides design reference for piezoelectric material application, such as sensors, actuators and ultrasonic motors.     

Survey of the present state of the art of piezoelectric linear motors

Piezoelectric ultrasonic motors have been investigated for several years and have already found their first practical applications. Their key feature is that they are able to produce a high thrust force related to their volume. Beside rotary drives like the travelling wave motor, linear drives have also been developed, but only a few are presently commercially available. In the present paper, we first describe the state of the art of linear piezoelectric motors. The motors are characterized with respect to their no-load velocity, maximum thrust force, efficiency and other technical properties. In the second part, we present a new motor, which is judged to be capable of surpassing the characteristics of other piezoelectric motors because of its unique design which allows the piezoelectric drive elements to be pre-stressed in the direction of their polarization. The piezoelectric elements convert energy using the longitudinal d33 effect which allows an improved reliability, large vibration amplitudes and excellent piezoelectric coupling. Energy loss by vibration damping is minimized, and the efficiency can be improved significantly. Experimental results show that the motor characteristics can be optimized for a particular task by choosing the appropriate operating parameters such as exciting voltage, exciting frequency and normal force.     

压电陶瓷超声波马达

压电陶瓷超声波马达是利用压电陶瓷材料激发超声波实现驱动的一种新型电机，同传统的电磁马达和静电马达比较，它具有低速下大力矩输出、无电磁干扰、静音操作、保持力矩大、响应速度快、结构简单等特点。在国外，它已经在精密仪器、航天航空、自动控制、办公自动化、微型机械系统、微装配、精密定位等领域得到了实际应用。文章系统地总结了电压陶瓷声马达的特点，简略介绍了国内外相关技术的发展发问及前沿性研究方向，并提出进一步开发研究的几点建议，希望会对我国压电陶瓷声马达的研究以及相应产品的开发起到积极的促进作用。     

A finite volume method and experimental study of a stator of a piezoelectric traveling wave rotary ultrasonic motor

Piezoelectric traveling wave rotary ultrasonic motors are motors that generate torque by using the friction force between a piezoelectric composite ring (or disk-shaped stator) and a metallic ring (or disk-shaped rotor) when a traveling wave is excited in the stator. The motor speed is proportional to the amplitude of the traveling wave and, in order to obtain large amplitudes, the stator is excited at frequencies close to its resonance frequency. This paper presents a non-empirical partial differential equations model for the stator, which is discretized using the finite volume method. The fundamental frequency of the discretized model is computed and compared to the experimentally-measured operating frequency of the stator of Shinsei USR60 piezoelectric motor.     

Piezoelectric linear motor concepts based on coupling of longitudinal vibrations

Classically, rotary motors with gears and spindle mechanisms are used to achieve translatory motion. In means of miniaturization and weight reduction piezoelectric linear motors are of interest. Several ultrasonic linear motors found in literature base on the use of two different vibration modes. Most often flexural and longitudinal modes are combined to achieve an elliptic micro-motion of surface points. This micro-motion is converted to direct linear (or translatory) motion of a driven slider. To gain high amplitudes of the micro-motion and thus having a powerful motor, the ultrasonic vibrator should be driven near the eigenfrequency of its modes. Additionally, low mechanical and electrical losses lead to increased efficiency and large amplitude magnification in resonance. This demands a geometrical design that fits the eigenfrequencies of the two different modes. A frequency-deviation of only a few percent leads to non-acceptable disturbance of the elliptical motion. Thus, the mechanical design of the vibrators has to be done very carefully. Within this contribution we discuss different motor designs based on the coupling of two the same longitudinal vibrations within one structure to generate an elliptic motion of surface points. Different concepts based on piezoelectric plates and Langevin transducers are compared. Benefits and drawbacks against the combination of longitudinal and bending modes will be discussed. Numerical results of the stator vibration as well as motor characteristics are validated by measurements on different prototypes.     

A curved ultrasonic actuator optimized for spherical motors: Design and experiments

Multi-degree-of-freedom angular actuators are commonly used in numerous mechatronic areas such as omnidirectional robots, robot articulations or inertially stabilized platforms. The conventional method to design these devices consists in placing multiple actuators in parallel or series using gimbals which are bulky and difficult to miniaturize. Motors using a spherical rotor are interesting for miniature multidegree-of-freedom actuators. In this paper, a new actuator is proposed. It is based on a curved piezoelectric element which has its inner contact surface adapted to the diameter of the rotor. This adaptation allows to build spherical motors with a fully constrained rotor and without a need for additional guiding system. The work presents a design methodology based on modal finite element analysis. A methodology for mode selection is proposed and a sensitivity analysis of the final geometry to uncertainties and added masses is discussed. Finally, experimental results that validate the actuator concept on a single degree-of-freedom ultrasonic motor set-up are presented.     

Analysis of a disk-type stator for the piezoelectric ultrasonic motor using impedance matrix

Impedance and admittance matrices of a piezoelectric annular actuator with segmented electrodes are presented for the analysis of the disk-type piezoelectric ultrasonic motors (USM). Equations of motion and the conjugate parameters for the impedance and admittance matrices are derived using the variational principle. In the derivation, the electric field in the piezoelectric layer is assumed to be constant over the area covered by a particular electrode, and the effects of both shear deformation and rotary inertia are taken into account. The resonance and antiresonance frequencies and the vibrating modes are calculated for the various resonance modes and boundary conditions, and the results are compared with those by the three-dimensional finite element methods. They are in excellent agreement with each other. It is expected that the derived impedance matrix can be effectively applied to the analysis and the design of the USM.     

Numerical simulation and experimental validation of ultrasonic de-icing system for wind turbine blade

It is widely accepted that wind energy is clean and renewable. However, icing on the blade surfaces of wind turbines is a serious problem in cold regions, which greatly affects its performance. Therefore, it is important to prevent ice accumulation on the surface of wind turbine blade and remove it whenever necessary. In this paper, a new non-thermal method–ultrasonic de-icing for wind turbine blade is proposed. Firstly, baced on the theory of ultrasonic de-icing, the harmonic analysis of the structure of the composite plate-ice layered system is investigated using the finite element method. The simulation results showed that ultrasonic de-icing method is feasible for wind turbine blade de-icing purposes. Secondly, the de-icing experiment of wind turbine blades using piezoelectric actuators is carried out in the freezer at a temperature of −15 °C, results showed that the ice layer can be debonded from the surface of wind turbine blade by the commonly used piezoelectric transducers made by PZT-5. The optimal frequency of ultrasonic de-icing of wind turbine blade is also given; finally, the installation way of ultrasonic transducers on the inner surface of wind turbine blade is given.     

A modified axisymmetric finite element for the 3-D vibration analysis of piezoelectric laminated circular and annular plates

A finite element is presented to analyze the three-dimensional (3-D) vibration of piezoelectric coupled circular and annular plates. The proposed finite element is a modification of a conventional axisymmetric finite element and is capable of conducting both axisymmetric and nonaxisymmetric vibration analysis of circular and annular laminated plates, with piezoelectric layers therein. The present formulation, a two-dimensional model itself, can investigate 3-D vibration of those plates for a preselected number of nodal diameters, and is therefore more economical than the conventional 3-D finite element analysis, yet still has almost the same accuracy and versatility as the 3-D analysis. In cases such as analysis of stators of traveling wave ultrasonic motors where only vibration modes with particular numbers of nodal diameters are of interest, the proposed approach is very convenient and useful.