基于弯曲模态的板形直线超声电机结构设计

板形直线超声电机因具有扁平化结构等特点，特别适用于电机安置空间狭窄的直线驱动场合。针对狭窄空间作动需求，提出一种单模态、大推力直线超声电机。电机由导轨和板形定子组成，定子由平面内两个垂直放置的矩形板联接构成L形结构，驱动足位于联接部顶端。电机利用两矩形板弯曲振动所形成的对称和反对称模态驱动导轨运动，并通过切换对称和反对称模态实现导轨正反向运动。首先通过定子模态分析，研究结构参数对振型的影响，以确定夹持和压电陶瓷片的安置位置；其次针对对称模态下驱动足处振幅过小问题，分析前端盖开槽对驱动足处振幅的影响规律，并通过开圆弧形槽增加驱动足处振幅。最后制作样机，并开展实验研究。实验表明：该电机结构简单紧凑、运行稳定且推力大，最大空载速度为329 mm/s，最大推力为70 N，推重比达38.2。
Abstract：Due to its flat structure, a plate-shaped linear ultrasonic motor (LUSM) is specially suitable for linear driving occasions with narrow motor installation space.Aiming at the demand of operation in narrow space, a novel single-mode-drive-type LUSM with high thrust was proposed here.The motor was composed of a guide rail and a plate-shaped stator.The stator was a L-shape planar structure composed of two connected rectangular plates perpendicular to each other with a driving foot located at the top of the connecting part.Symmetric and antisymmetric bending vibration modes of the two rectangular plates were adopted by the motor to drive the guide rail.By switching symmetric and anti-symmetric modes, the forward and backward motion of the guide rail was realized.Firstly, through the stator’s modal analysis, influences of structural parameters on modal shapes were studied to determine the clamping location and installation positions of piezoelectric ceramic chips.Secondly, in order to solve the problem of too small amplitude of the driving foot under symmetric modes, the influence law of the front cover slotting on the driving foot amplitude was analyzed, and opening an arc groove made the amplitude of the driving foot increase.Finally, the motor’s prototypes were fabricated and tested.The test results showed that the motor has simple and compact structure, stable operation and large thrust with the maximum unloaded velocity of 329 mm/s, the maximum thrust force of 70 N, and the thrust-weight ratio of 38.2.