纵弯复合多自由度球形超声电机的研究

摘 要：目前国内外对多自由度超声电机的研究和应用尚属探索阶段,出现了多种结构的多自由度超声电机。本文提出了一种新型单振子纵弯夹心换能器式超声电机结构,由单一驱动足产生多自由度振动轨迹,驱动球形转子作多自由度运动;对十字交叉换能器做了模态分析,对纵振和弯振做了模态简并;建立了驱动足的运动轨迹方程,并仿真分析了典型驱动方式下驱动足的振动轨迹;试验测试了样机转子绕X、Y、Z轴转动的速度与电压之间的关系和转矩与速度之间的关系,计算了相应情况下电机的最大效率;电机旋转方向与分析结果一致。
     

单相斜轨塔形直线超声电机设计与实验

对一种理论斜直线运动轨迹的单相驱动双向运动的直线超声电机进行了理论及实验研究.该电机由塔形定子和倾斜一定角度安装的导轨组成,定子的两个正交工作模态为y-z面内对称振动模态和x-z面内弯振模态,分别对应电机的正反运动方向,利用在工作模态下定子驱动足表面质点相对于导轨的理论斜直线运动来驱动导轨运动.分析了电机的工作原理,推导了电机运行的导轨倾角范围,研制了样机,并进行了模态实验和机械特性实验.实验表明:在导轨倾斜角为35°、激励电压500 Vp-p、预压力4.5 N下,当电机工作在y-z面内对称振动模态,电机正向运动,最大空载速度为79 mm/s,最大输出力为0.5 N;当电机工作在x-z面内弯振模态,电机反向运动,最大空载速度为756 mm/s,最大输出力0.8 N.     

纵弯模态复合型直线超声电机定子质心振动研究

针对纵弯模态复合型直线超声电机的质心振动问题,采用等效非线性弹簧层接触理论,建立了刚性平面接触模型和定子法向运动的动力学模型,进而解出一阶纵振模态和定子质心振动的动力学方程,得出质心振动的稳态解。根据建立的模型,分析了定子质心振动对电机机械输出性能的影响;并通过MATLAB仿真计算进一步分析了预压力弹簧刚度、预压力大小等因素对定子质心振动响应的影响。最后制作样机并开展了实验研究。实验表明模型是有效的,该研究可以为直线超声电机的动力学建模和结构优化设计提供理论依据。     

行波热声斯特林热机起振模态的实验研究

设计和建造了一台小型的行波热声发动机，实现了与谐振管负荷的耦和匹配。介绍了所研究的热声系统中热声振荡过程的一些实验结果和实验中观察到的两个起振模态以及模态间周期性交替变化的现象，对影响起振模态的因素进行了实验研究和分析。     

Ⅳ型弯张换能器的数字建模

Ⅳ型弯换能器的振动机理比较复杂,它包涵着驱动振子的振动、壳体的振动、水介质振动及它们之间相互耦合而构成的复合振动。本文对其进行了较详细的理论分析,给出了换能器壳体的振动位移分布和谐振频率。并根据干模态讨论了换能器在水中的声辐射特性;再者,结合压电方程及换能器的振速、应力分布给出了换能器在水中的电机声等效电路。理论分析结果与有限元法及实验测量进行比较,符合较好。     

IV型弯张换能器的数学建模

ＩＶ型弯张换能器的振动机理比较复杂,它包涵着驱动振子的振动、壳体的振动、 水介质振动及它们之间相互耦合而构成的复合振动。本文对其进行了较详细的理论分析,给 出了换能器壳体的振动位移分布和谐振频率。并根据干模态讨论了换能器在水中的声辐射特 性;再者,结合压电方程及换能器的振速、应力分布给出了换能器在水中的电机声等效电路。 理论分析结果与有限元法及实验测量进行了比较,符合较好。     

H-结构薄板纵弯复合模态驱动的压电直线电机

为高性能压电直线电机设计奠定基础,推出基于H型振子的直线电机并利用该振子两纵向杆面内一阶纵振与二阶弯振驱动电机。研究电机的驱动机理并从理论上阐释振子纵杆驱动端质点的椭圆运动形成过程;建立振子有限元模型并对其工作模态、灵敏度、谐响应进行分析;优化振子结构尺寸,完成电机装配结构设计并制作出振子、电机实物;对振子进行模态试验,结果显示该振子不仅具有预设的工作模态,且在正常激励条件下,驱动端纵、弯振幅值分别可达1.2 μm,1.4 μm。研究表明,该电机有望产生较大速度与动力。     

U型变截面薄板面内复合模态驱动的直线超声电机

提出一种U型变截面薄板结构驱动的压电直线超声电机,选定U板两纵杆的一阶反对称纵振和二阶对称弯振为工作模态。阐释了电机驱动机理,推导了定子驱动端椭圆运动轨迹;基于纵、弯工作模态频率一致性模型,优化了电机结构尺寸;通过谐响应分析及激光测振试验,证实了定子工作模态的存在及其纯正性;设计出电机装配结构,制作出其原型样机;构建电机驱动控制平台,驱动电机运转,验证电机原理的可行性。通过速度特性试验发现:当驱动频率为78.11 kHz且电压幅值为240 V时,电机最大运动速度可达125.6 mm/s。     

基于振型假定的旋转行波超声电机动力学模型分析

利用分析动力学的Lagrange方程,采用假定振型法将压电陶瓷诱发应变的激振效果等效成单自由度弹簧-质量系统在外力作用下的强迫振动,建立了基于压电陶瓷诱发应变激振的超声电机复合定子的机电动力学模型,可以计算出超声电机定子在特定模态下的模态质量、模态刚度、交变电压激振压电陶瓷的等效力系数等参数.     

基于多普勒激光测振仪的Ⅲ型弯张换能器振动模态分析

为了测量和验证Ⅲ型弯张换能器在工作状态时辐射面的振动情况,采用多普勒激光测振仪对Ⅲ型弯张换能器的振动模态进行了测量,并与有限元软件仿真结果进行了对比。测量得到换能器壳体的一阶振动模态的谐振频率为1729 Hz,换能器一阶振动模态的谐振频率为2 065 Hz,与有限元模态仿真结果吻合较好。研究结果表明,多普勒激光测振仪能较好地对换能器的振动模态进行测量,可用于换能器的辅助设计。     

A cylindrical traveling wave ultrasonic motor using a circumferential composite transducer

This paper intends to present and verify a new idea for constructing traveling wave ultrasonic motors that may effectively avoid the drawbacks of conventional traveling wave motors using bonded PZT plates as the exciting elements. In the configuration of the motor's stator, a composite sandwich type transducer is used to excite a traveling wave in a cylinder with two cantilevers as the coupling bridges between the transducer and the cylinder. The design process of the stator is described using the FEM modal analysis method, and the establishment of traveling wave on the cylindrical stator was simulated by FEM transient analysis. To verify the theoretical analysis results, a laser Doppler scanner was employed to test the mode shapes of a prototype stator excited by the longitudinal and bending vibrations respectively. Finally, to validate the design idea, a prototype motor was fabricated and tested; the typical output features are no-load speed of 156 rpm and maximum torque of 0.75 N·m under exciting voltages of 70 V(rms) applied to excite the longitudinal vibration of the transducer and 200 V(rms) applied to excite the bending vibration.     

A U-shaped linear ultrasonic motor using longitudinal vibration transducers with double feet

A U-shaped linear ultrasonic motor using longitudinal vibration transducers with double feet was proposed in this paper. The proposed motor contains a horizontal transducer and two vertical transducers. The horizontal transducer includes two exponential shape horns located at the leading ends, and each vertical transducer contains one exponential shape horn. The horns of the horizontal transducer and the vertical transducer intersect at the tip ends where the driving feet are located. Longitudinal vibrations are superimposed in the motor and generate elliptical motions at the driving feet. The two vibration modes of the motor are discussed, and the motion trajectories of driving feet are deduced. By adjusting the structural parameters, the resonance frequencies of two vibration modes were degenerated. A prototype motor was fabricated and measured. Typical output of the prototype is no-load speed of 854 mm/s and maximum thrust force of 40 N at a voltage of 200 V(rms).     

A travelling wave rotary motor driven by three pairs of Langevin transducers

In this work, numerical simulations and experimental measurements carried out on a high-power ultrasonic motor are presented. The proposed motor is composed of an annular shaped stator and two cone-shaped rotors. The rotors are pressed into contact with the edges of the inner surface of the stator by means of a pre-stress system. A traveling rotating wave is generated in the stator by three pairs of Langevin transducers suitably shifted both in space and time. Each transducer is designed to excite radial nonaxisymmetric modes in the ring. The motor has been effectively clamped to the housing by using two flanges passing through the middle plane of 2 transducers. Finite element analysis was employed to evaluate two different configurations of the motor, both using 6 driving transducers, and to analyze the effect of the flange on the design and on the performance of the transducer. Experimental measurements carried out on a manufactured prototype show that the proposed motor exhibits greatly improved performance in terms of output torque and mechanical power compared with similar previous prototypes which use fewer driving transducers and a different clamping system. The motor weighed 0.67 kg, and had a working frequency of 23.6 kHz, maximum rotational speed of 116 rpm, and static torque of 0.94 Nm.     

纵弯转换超声振动雾化系统的振动特性与设计研究

提出了由纵向振动系统与弯曲振动圆盘组成的纵弯转换超声振动雾化系统的新型结构。通过理论分析和有限元分析,揭示了由换能器、变幅杆与工具组成的振动系统的各种谐振状态特性, 研究了系统的谐振设计方法。分析表明：新型雾化振动系统工作于负载谐振模式,其谐振频率主要取决于纵振动系统的结构,弯曲振动薄圆盘相当于系统的负载。当弯曲振动圆盘谐振频率与系统的谐振频率越接近时,系统的输出振幅越大。通过实验证明了理论研究正确性。     

质量偏心Timoshenko梁的振动波特性研究

在研究船舶、潜艇等工程结构的低频振动时,通常可以将其简化为质量在截面内分布非均匀的梁结构,此质量偏心会引起弯-纵耦合。针对弯-纵耦合的质量偏心Timoshenko梁,推导了其截止频率的解析表达式;探讨了质量偏心对其纵振波、传播弯曲波及衰减弯曲波波数的影响规律;研究了三组波数下纵向/弯曲位移比随频率及质量偏心的变化。分析结果表明,质量偏心会降低梁的截止频率,偏心率越大,降低越明显;弯曲衰减波会在截止频率处转变为弯曲传播波;质量偏心使得非频散的纵向振动波转变为频散波;纵向振动与弯曲振动的耦合在质量偏心率或频率增大时,会进一步加强。     

用于超声清洗复合振动换能器的研究

本文研究了一种由纵向振动夹心式压电超声换能器与弯曲圆盘组成的用于液体中超声处理的复合振动辐射器。推出了恢复合振动系统的共振频率设计方程，分析了各个振动模式的机电转换特性及其声波辐射特性，测量了振动系统的共振频率及其有效机电耦合系数。从实验及理论结果可以看出，振动系统的频率测试值与设计值基本符合。在一定的共振频率上，该振动系统具有最大的有效机电耦合系数，是一种很有前途的功率超声辐射器。     

气介式功率超声复合换能器的声辐射特性研究

本文对气介式功率超声复合换能器的辐射声场进行了理论计算并与实验结果进行了对比。该复合换能器由夹心式纵向振动半波长换能器及弯曲振动的薄圆盘组成。从理论上推出了弯曲振动辐射圆盘在不同边界条件下的辐射声场分布及其共振频率方程。理论分析结果表明,固定边界弯曲振动圆盘辐射声场的指向性最佳,并且指向性的理论计算结果与实验结果符合很好。     

Traveling wave excitation in a flexural vibration ring by using a torsional-flexural composite transducer

This paper presents a new mechanism for traveling wave excitation of the flexural vibration in a ring. A torsional-flexural composite transducer was used to excite two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the ring. The prototype, composed of a 32-mm diameter composite transducer attached along the outer edge of an 180-mm diameter aluminum annular ring, was designed, constructed, and tested. The ring was designed via finite element analysis to operate using a (0,8) transverse flexural traveling wave, and the motion was confirmed experimentally     

Piezoelectric ceramic rectangular transducers in flexural vibration

Based on the equivalent elastic method and coupled vibration theory, an analytic method is presented to study the flexural vibration of rectangular transducers consisting of piezoelectric ceramic thin plates. By introducing a mechanical coupling coefficient, the flexural vibration of the piezoelectric ceramic rectangular thin plate is reduced to two simple, one-dimensional flexural vibrations of narrow piezoelectric ceramic strips. The resonance frequency equations for the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration are derived under the free and simply supported boundary conditions analytically. The relationship between the resonance frequency and the flexural vibrational order, the geometrical shape, and the dimensions of the piezoelectric ceramic rectangular thin-plate transducer is analyzed. It is demonstrated that the one-dimensional vibrational theory for the flexural vibration of a narrow piezoelectric ceramic strip and the stripe-mode flexural vibrational theory for the piezoelectric ceramic rectangular thin plate can be derived directly from the theory obtained in this paper. Experimental results show that the measured resonance frequencies of the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration under free-boundary conditions are in good agreement with the calculated results. The method presented in this paper can be used in the resonance frequency analysis of vibrating systems in coupled vibration.     

A rotary ultrasonic motor using bending vibration transducers

A rotary ultrasonic motor using bending vibration transducers is proposed. In each transducer, two orthogonal bending vibrations are superimposed and an elliptical trajectory is generated at the driving foot. Typical output of the prototype is a no-load speed of 58 rpm and maximum torque of 9·5 Nm under an exciting voltage of 200 V(rms).