Piezoelectric Ring-Morph Actuators for Valve Application

This paper presents piezoelectric ring-morph actuators designed to produce a large flexural displacement for valve actuation application. The ring-shaped piezoelectric plate in the actuator produces a radial contraction or expansion and causes the center part of the metal disc to generate a large flexural displacement. The PZT ring creates a space under the metal disc which permits it to bend with a curvature larger than that of the conventional bimorph in the axis direction of the ring-morph when the PZT ring under the metal disc contracts. A prototype with diameter of 25.4 mm and thickness of 0.55 mm could produce a total stroke (static displacement) of over 130 m under a driving voltage of ±300 V and a load of 2 N. The maximum generative force of ring-morph actuator was about 30 N.     

提高蠕动式压电直线驱动器输出力的研究进展

蠕动式压电直线驱动器具有大位移行程和高位移分辨率的特点,但是箝位机构利用静摩擦力输出负载的方式大大限制了系统的进给刚度和输出推力.从箝位机构的结构类型、运动方式以及和新材料新技术的交叉应用等方面,介绍了几种典型尺蠖驱动器的研究进展,为提高系统的输出力,指出了今后的研究方向.     

非接触式球形转子压电作动器的研究

提出了一种基于近声场悬浮的非接触式球形转子压电作动器,由压电陶瓷激发碗式定子产生两相B04驻波并合成一高声强行波,进而诱发高声强声场来同时悬浮和驱动球形转子。建立了非接触式球形转子压电作动器的有限元模型,对定子进行了动力学分析与优化设计,确定了结构方案,最后加工、制造了样机。通过试验得到了定子的振动参数,搭建了整个样机的测试系统,对其悬浮和驱动特性进行了分析,结果表明球形转子在近声场的作用下成功地实现了非接触式旋转。     

Novel Piezoelectric-Based Power Supply for Driving Piezoelectric Actuators Designed for Active Vibration Damping Applications

This paper describes a novel step-up DC-AC piezoelectric-based power supply for driving piezoelectric actuators. Piezoelectric actuators have been demonstrated to be very attractive in applications requiring fast response and high actuation force, such as active damping applications. These actuators are commonly installed in self-powered systems (cars, helicopters, aircrafts, satellites, etc.) with limitation in the battery performance, dimensions and maximum weight. Nevertheless, the required driving electrical AC voltage for these actuators is typically in the range of 100 V to 1000 V, quite far from the 9 to 24 V of common batteries. Thus, the use of heavy, large and EMI-noisy electromagnetic transformers becomes necessary which is a drawback for the compact size required. This paper introduces an alternative system for driving piezoelectric actuators using a novel design of piezoelectric transformer, the Transoner®. The proposed solution allows a reduction in size, weight and magnetic noise generation compared to the classical electromagnetic-based systems. The work represents a completely novel approach to the possibilities of piezoelectric transformers for powering high voltage piezoelectric actuators. The solution offers significant advantages in environments requiring high integration, low weight, and low electromagnetic interferences operated with batteries. A circuit configuration capable of converting a 24 V DC input voltage up to 600 V _pp AC output voltage with frequency and magnitude control is implemented. Experimental results are presented for a standard multilayer piezoelectric actuator driven at 100 V _pp within the range of 10 Hz to 500 Hz.     

直线型超声波电动机压电作动器的位移特性研究

由于压电作动器的位移特性对直线超声波电动机的性能有较大的影响,以单层和叠堆压电陶瓷作动器为对象,分别通过理论和计算机模拟对其位移特性进行分析,得出了影响压电作动器位移特性的主要因素,为研制新型叠堆压电陶瓷作动器和开发精密直线型超声波电动机提供理论参考。     

Piezoelectric Energy Harvesting under High Pre-Stressed Cyclic Vibrations

Cymbal transducers have been found as a promising structure for piezoelectric energy harvesting under high force (∼ 100 N) at cyclic conditions (∼ 100–200 Hz). The thicker steel cap enhances the endurance of the ceramic to sustain higher ac loads along with stress amplification. This study reports the performance of the cymbal transducer under ac force of 70 N with a pre-stress load of 67 N at 100 Hz frequency. At this frequency and force level, 52 mW power was generated from a cymbal measured across a 400 kΩ resistor. The ceramic diameter was fixed at 29 mm and various thicknesses were experimented to optimize the performance. The results showed that the PZT ceramic of 1 mm thickness provided the highest power output with 0.4 mm endcap. In order to accommodate such high dynamic pressure the transducer and cap materials were modified and it was found that the higher piezoelectric voltage constant ceramic provided the higher output power. Electrical output power as a function of applied ac stress magnitude was also computed using FEM analysis and the results were found to be functionally coherent with experiment. This study clearly demonstrated the feasibility of using piezoelectric transducers for harvesting energy from high magnitude vibration sources such as automobile.     

Solid Freeform Fabrication of Piezoelectric Actuators by a Micro-Casting Method

In recent years, there has been much interest in the manufacturing of piezoceramic actuators by Solid Freeform Fabrication (SFF) methods, following developments in polymer and metal shaping. With these methods, actuator shapes can be realized that are impossible or very difficult to obtain by traditional ceramic shaping techniques. At TNO, research is currently performed on the development of technology to use SFF methods to develop multi-material components, i.e. combining polymers, ceramics and metals in one production process. One SFF-technique, which is investigated in this study, is micro-casting. In this process, a highly loaded ceramic suspension is deposited by a nozzle, attached to a computer-controlled positioning system. With this process, it is possible to make 3D components directly from CAD files, or to fill volumes using wider nozzles. As a case study, such a casting process was used to produce a piezo-electric bender and an ultrasonic transducer element.     

An Overview of Rapidly Prototyped Piezoelectric Actuators and Grain-Oriented Ceramics

Rapid prototyping (RP) has been used to fabricate a series of piezoelectric actuators, including spiral and tube actuators, to study the actuation mechanism in these geometries, and to obtain enhanced properties. PZT spiral actuators showed large displacement in mm range, and moderate blocking force. Unimorph spirals (PZT/metal shim) and dual-material (piezoelectric/electrostrictive) PMN-PT spirals were also prototyped and characterized. Tube actuators with inward and outward wall curvature showed slight improvement in axial and radial displacements compared to conventional straight-walled tube actuators. In order to improve the performance of ceramic actuators with polycrystalline microstructures, grain-oriented ceramics of bismuth titanate, lead metaniobate, and PMN-PT were investigated. Texturing was achieved by incorporating anisometric seeds into RP feedstock, aligning them during fabrication, and growing the seeds (templates) at elevated temperatures. Synthesis of anisometric seeds and pertinent processing conditions of the textured ceramics are presented. The feasibility of making net shape single crystal components was also explored. Single crystals of 0.65PMN-0.35PT were grown in FDC components using embedded (111) and (110) SrTiO₃ seeds at 1250°C.     

Micro Piezoelectric Ultrasonic Motors

This paper reviews recent developments of micro ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, four ultrasonic motors recently developed at Penn State University are introduced; windmill, PZT tube, metal tube, and shear-type motors. Driving principles and motor characteristics are described in comparison with the conventional ultrasonic motors. Motors with 1.5 mm in diameter and 0.8 mNm in torque have been actually developed.     

Poling of pyroelectric thin films

Abstract

Poling of calcium and zirconium modified lead titanate pyroelelectric thin films has been studied. Poling temperature and electrical field were optimized to achieve high figure of merits. It was found that thermal activation is important to obtain highly poled films. Defect-dipole complexes are supposed to play a major role to retain the polarization and also to enhance it. Porous calcium substituted films achieved an up to three times higer voltage response than zirconate substituted thin films, because porosity decreased the dielectric constant significantly.     

一种矩形振子新型压电直线电机

分析了振子面内弯曲模态的激发原理及电机的驱动机理。通过Ansys分析计算,得到了压电振子面内两种弯曲模态的频率,并对压电振子及电机结构进行了设计。研制了一种基于矩形复合层板面内弯曲模态压电直线电机,并进行了相应的实验研究。研究表明：当激励信号电压为380 V,频率为65.2 kHz时,电机最大运行速度约为458.3 mm/s,驱动力为2.2 N,且正反向运行良好。     

Development and Electromechanical Properties of Multimaterial Piezoelectric and Electrostrictive PMN-PT Monomorph Actuators

Monolithic multimaterial monomorphs, comprised of varying ratios of piezoelectric 0.65Pb(Mg_1/3 Nb_2/3)O₃-0.35PbTiO₃ to electrostrictive 0.90Pb(Mg_1/3Nb_2/3)O₃-0.10PbTiO₃, have been co-fired at 1150^∘C. The relative permittivity, displacement, and polarization hysteresis were investigated for varying ratios of piezoelectric to electrostrictive material. The permittivity of the 1:1 multimaterial monomorphs followed the dielectric mixing laws, showing a dielectric constant of 5,500 at room temperature. The P-E hysteresis loop of the 1:1 sample exhibited a maximum and remnant polarization slightly less than the piezoelectric PMN-PT 65/35, but higher than the electrostrictive PMN-PT 90/10. Displacement was found to be higher for the 3:1 monolithic monomorph actuators, reaching 76 μ m at 6 kV/cm. The results indicate that by minimizing the electrostrictive layer thickness the tip displacement can be substantially increased while maintaining a lower hysteresis than that of the purely piezoelectric counterpart.     

Levitation Caused by the Vertical Vibration of a Piezoelectric Actuator

Levitation caused by the vertical vibration of a piezoelectric actuator is studied here. Levitation mechanisms levitate using a squeeze effect generated by the vertical vibration. The levitation mechanisms usually levitate at the resonance frequency. However, if the vibration amplitude of the piezoelectric actuator at the resonance frequency is small, the levitation mechanism does not levitate. Therefore, the vibration amplitude affects the levitation height of the mechanism. In this paper, we describe the applied voltage, the load current, the power consumption, and the phase difference between the voltage and current.     

一种结构简单的高精度压电尺蠖式位移致动器

介绍了一种结构简单、易装配的高精度压电尺蠖式位移致动器,阐述了致动器的工作原理和结构.致动器采用叠堆式压电陶瓷作为驱动,利用柔性铰链作为位移放大机构,能够可靠地实现光轴的双向运动.位移分辨率可以达到纳米级别,步距可以在几纳米至几毫米之间任意选择.     

A Stackable Bonding-Free Flextensional Piezoelectric Actuator

A flextensional actuator was designed using commercial multilayer stacked actuator so as to produce large displacements at intermediate force levels. The simple design chosen eliminated the need for bonding the actuators into the frame and permitted easy series connection of multiple units. To satisfy the need for a fiber grating tuning device to interrogate an array of Bragg grating fiber optic stress sensors, a tuning device using four series connected units was constructed. The unit performs well, but the actual measured amplification is less than theoretical expectation. The problem was traced to unwanted flexing of the simple original frame and a hinged more robust flexing beam construction was shown to eliminate the problem.     

基于压电驱动技术的细胞微量注射装置

提出了用压电陶瓷在通电下产生的微小变形的原理来设计压电驱动器,利用微位移压电驱动器来完成细胞微量注射微动平台的定位和注射,并且将微动平台和由电机带动的细胞微载台来构成细胞药物微量注射的机械结构与控制系统。压电式细胞微量注射装置的定位和注射动作全部由压电驱动器来完成,和目前国内外的细胞微量注射装置相比主要特点是定位精度和注射精度都比较高。     

压电陶瓷变压器的线性及非线性模型

在研究压电陶瓷变压器的电气特性及其应用时，压电陶瓷变压器的等效电路模型是其基础之一。根据压电陶瓷变压器的不同工况，给出了4种电路模型，并给出了提取电路参数的方法，当压电陶瓷变压器工作在高电压－大电流工况时，应用模型4所得的理论功耗与实验结果有很好的一致性。     

Water-Immersible Micromachined Pb(Zr, Ti)O3 Thin Film Actuators

We demonstrate a water-immersible thin film lead zirconate titanate, Pb(Zr, Ti)O₃, [PZT] actuator, without special passivation layer, towards in-vivo or in-vitro scanning probe microscope (SPM) measurements of living cells in water or biological fluids. In order to be water-immersible, the electrodes need to be electrically insulated and the piezoelectric layer needs to be protected against direct water contact. This paper describes our design solution with a simple fabrication process for a water-immersible piezoelectric device, which separates the bottom electrode from the top electrode by having a narrow ditch covered with PZT film. The PZT film is then encapsulated with the top metal electrode without insulation layer. In this structure, the PZT is sandwiched between the top and bottom metal electrodes to prevent water permeation. The device is fabricated using lift-off processing for the bottom and top electrodes, sol-gel spinning for the PZT thin film and wet etching for the PZT patterning. The piezoelectric constant, d₃₁, is about –100 pC/N. The dielectric polarization and fatigue properties of the devices were measured in air and water. The spontaneous polarization, remnant polarization, coercive field and dielectric constant are 54 C/cm², 15 C/cm², 60 kV/cm and 1200, respectively. The polarization property of the device was unchanged in either air or water up to 1 × 10⁹ continuous cycles.     

国内外直线超声电机的研究现状及关键技术

分析了直线超声电机的优点，按时间顺序介绍了国内外直线超声电机的研究状况，并给出了一些典型的电机形式及其工作原理；提出了当今直线超声电机研究中存在的问题及需要加强研究的关键技术。     

压电执行器与应变计复合的电压传感器

将压电陶瓷执行器与悬臂梁式应变传感器通过纵-弯转换机械结构复合,设计了一种“电压-力-应变”转换的新型电压传感器。压电陶瓷执行器与弹性悬臂梁结构“T形”连接构成纵-弯转换结构,将压电执行器在电压作用下产生的纵向应力/应变转换为悬臂梁的弯曲应力/应变,实现应力/应变的纵向-弯曲转换。布置在弹性悬臂梁结构上下两侧的4个电阻应变片组成惠斯通电桥电路,实现对悬臂梁弯曲应力/应变的测量。高电压强电侧和力敏感的弱电侧之间的机械转换设计,保证了高度电气隔离。建立了传感器“电压-力-应变”转换物理模型并通过有限元仿真进行了验证。制备了传感器样机,测试结果表明,量程0～5 000 V,灵敏度为0.01μV/V,非线性误差1.83%,分辨率30 V。