【作者】 万志坚；

【导师】 胡泓；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2014， 博士

【摘要】 超声电动机是近三十多年来发展起来的一种全新概念的驱动装置。与传统电磁电机相比，超声电机具有结构简单、能量密度大、启停灵敏、位置分辨率高、断电自锁、低振动、低噪声、无电磁干扰等特点。所以它在航天器、微小型机械、精密仪器、小功率驱动等方面的应用具有明显的优越性。直线超声电机是超声电机的一个分支，它通过定子和滑块（或者动子）之间的摩擦耦合输出直线运动和推力。由于其结构简单，可以直接输出直线运动，不需要运动转换机构，所以除了具有旋转型超声电机的一般特点外，直线超声电机的定位精度和速度控制精度更高，可达纳米级精度。本文提出了一种新型面内弯纵型直线超声电机。该电机的定子由一块青铜矩形板和八片压电陶瓷片组成，电机利用矩形板的面内二阶弯曲振动和一阶纵向振动的复合模态来工作。由于矩形板的宽度远小于厚度，其面内弯曲振动难以被激发，所以，本研究中，在青铜矩形板的适当位置开设了若干长条形孔来解决这个问题，并利用瑞利-里兹法确定了长条形孔的最佳长度尺寸。在电压信号的激励下，压电陶瓷片产生超声频率的伸缩振动，并激发出矩形板定子的面内弯纵复合模态，使矩形金属板产生共振，并使矩形板上的驱动足产生椭圆运动。通过摩擦耦合将驱动足的椭圆运动变成电机滑块的直线运动，从而实现直线电机的动力输出。分析了压电材料的逆压电效应，从矩形板定子面内二阶弯曲振动和一阶纵向振动的振动方程出发，建立了矩形板定子的机电耦合动力学模型，计算了压电陶瓷片对定子所施加的面内二阶弯曲振动和一阶纵向振动的模态力，给出了若干压电陶瓷片的合理安装位置，解释了定子驱动足椭圆运动的形成机理。应用有限元分析软件建立了面内弯纵型直线电机定子的有限元模型，对电机定子进行全面的仿真分析，包括模态分析、谐响应分析、瞬态动力学分析和接触分析。通过仿真，得到了定子的振型，优化了电机的结构尺寸，计算了定子产生面内纵弯复合振动时的最佳频率，验证了定子驱动足的椭圆运动的形成机理，比较了矩形板开孔前后定子的振幅、频率等变化，并通过接触分析证明了这种直线超声电机设计方案的可行性。课题对弯纵型直线超声电机进行驱动和摩擦分析，从定子驱动足质点的椭圆运动研究入手，以新的视角分析了驱动足质点的椭圆运动对动子运动的驱动和阻碍机理，提出了定子质心位置和定子两端的作用力随着定子的振动而变化的观点。在此基础上，分析了定子和动子摩擦界面间的粘、滑摩擦机理，指出驱动足对动子的驱动方式为跳跃式驱动，且定子驱动足相对于动子适当的“跳跃”有利于电机的动力输出，还指出定子驱动足的“跳跃”高度取决于预压弹簧刚度、动子摩擦层的刚度、电机预压力、驱动足振幅等因素。为验证本课题所设计和制造的新型超声电机合理性和可行性，加工制作了直线超声电机的样机，搭建了实验平台并进行了相关的实验。在实验中，对定子矩形板是否开孔两种情况进行了比较实验，证明矩形板开孔后可以扩大定子的振幅，特别是面内弯曲振动的振动幅度，并且电机的输出速度和最大输出力明显加大。更多还原

【Abstract】 The ultrasonic motor which has been developed rapidly in recent thirty years is a new-concept motor. Compared with the conventional electromagnetic motors, the ultrasonic motor has many advantages, such as simple structure, high energy density, high sensitivity during the start and stop of the motor, high resolution, self-locking when power-off occurs, low vibration and noise, no electromagnetic interference etc. As a result, the ultrasonic motors have significant superiority for the application in the spacecrafts, micro-machinery, precision instruments, low-power actuation etc. The linear ultrasonic motor is an important part of the ultrasonic motors, which can directly output linear motion and force through the friction between the stator and the mover. Besides the general character of the rotary ultrasonic motor, the linear ultrasonic motor has higher accuracy of positioning and speed control due to the fact that the linear ultrasonic motor has simple structure and the capability of directly outputting linear motion without switching mechanism, it can even achieve the accuracy of nanoscale.The stator of this motor is composed of one rectangular bronze plate and eight piezoceramics plates, and this motor works by making use of the composite mode of the second order bending (B2) vibration and first order longitudinal (L1) vibration in plane of the rectangular plate. Because the width of the rectangular plate is much less than the thickness, so the in-plane bending can be hardly excited. To solve this problem, many long rectangular apertures at proper positions on the bronze plate are designed in this study, and the optimal length of these apertures is determined by using the Rayleigh Ritz method. With the excitation of voltage signal, the piezoceramics plates vibrate with ultrasonic frequency, and the B2and L1composite mode of the rectangular plate will be excited, so that the rectangular plate will resonate and the driving-foot on the rectangular plate will move elliptically. The friction coupling will transform the elliptical motion of driving-foot into the linear motion of the slider of motor, and the power outputs of this linear motor can be consequently realized.The converse piezoelectric effect of the piezoceramics is analyzed, the electromechanical-coupled dynamic model is derived from the vibration equations of the B2and L1mode of the rectangular stator, the modal force of the B2vibration and L1vibration which are applied to the stator by the piezoceramicscs plate are calculated, the reasonable locations for installing the piezoceramicscs plates is determined, and the principle of the elliptical motion of driving-foot of the stator is proved. The finite element analysis software is used to establish the finite element model of the stator of the linear motor, and the comprehensive simulation analyses are conducted, including modal analysis, harmonic response analysis, transient dynamics analysis and contact analysis. Through the simulation, the mode of vibration of the stator is obtained, the structure size of the motor is optimized, the optimal frequency of the composite mode of the B2and L1of the stator is calculated, the mechanism of the elliptical motion of the driving-foot of stator is confirmed, the amplitude and the frequency of the rectangular plate without aperture are compared with that of the rectangular plate with aperture, and the feasibility of this linear ultrasonic motor is verified through the contact analysis.In this study, the principle of drive and friction of the linear ultrasonic motor with the composite mode of the B2and L1are analyzed. With the research on the elliptical motion of the particleof driving-foot of the stator, the mechanism that the particle of driving-foot can either drive the mover or oppose the motion of the mover is analyzed with a new perspective. The idea that the position of the stator’s barycenter, as well as the applied forces at both ends of the stator, changes with the vibration of the stator itself is proposed. Based on this idea, the stick-slip friction mechanism of the contact surface between the stator and mover is analyzed, the fact that the driving-foot leapingly drive the mover is pointed out, and the proper leaping of the driving-foot of stator relative to the mover can benefit the power outputs of the motor, the leaping height of the driving-foot of the stator depends on several factors, including the stiffness of the preloading spring, the stiffness of the mover’s friction layer, the preloading force of the motor and the amplitude of the driving-foot ect.To verify the reasonability and the feasibility of the novel ultrasonic motor proposed in this study, the prototype of this motor is fabricated, the experimental platform is set up, and several relevant experiments are conducted. Concretely, the comparison experiment between the conditions that the rectangular plate has and has not apertures is performed, which demonstrates that the amplitude of the rectangular plate is greatly enhanced, especially for the vibration amplitude of the in-plane bending vibration, and the maximum output speed and the maximum output force of the motor is greatly increased too.更多还原