A novel single mode linear type ultrasonic motor which is combining the 1st longitudinal vibration excited by the piezoelectric stack and the 4th bending vibration excited by the piezoelectric plates is proposed in this paper.The structure and the operating mechanism of this new type ultrasonic motor were firstly introduced.Then the electromechanical model of the motor stator is modeled with the finite element method, the vibrating modal and the operating frequency of the stator were determined based on the numerical simulate analyses of the stator vibration performances.The elliptical orbits equation of the stator driving feet were derived according to the longitudinal vibration theory of the elastic bar and the bending vibration theory of the beam;the effects of the phase difference between the two exciting voltages on the elliptical orbits were numerically analyzed.Finally, the effects of the preload, the exciting voltage amplitude and frequency on the mechanical performances of the motor were studied based on the stick-elastic contact mechanism.Simulation and numerical results show that the operating frequency of the single model linear ultrasonic motor is 39 860 Hz;the prototype motor achieves the maximum thrust of 19.1 N and no-load speed of 310 mm·s-1 when the exciting voltage Up-p is 100 V.%提出了一种融合一阶纵振和四阶弯曲振动模式的单模态直线超声波电动机,介绍了电动机的结构和运行机理,利用有限元方法建立了电动机定子的机电耦合模型,仿真分析了电动机定子的振动特性,确定了电动机定子工作模态和工作频率;利用弹性杆的纵振动和悬臂梁的弯曲振动理论建立了电动机驱动足椭圆运动轨迹方程,分析了激励电压相位差对电动机椭圆轨迹的影响;利用粘弹性接触机理给出了电动机的机械特性输出曲线,分析了预压力、激励电压幅值和激励频率等对电动机输出特性的影响.通过数值和仿真分析得出:单模态直线超声波电动机的工作频率为39 860 Hz,在外加激励电压Up-p=100 V时,电动机最大输出推力和空载速度分别达到19.1 N和310 mm·s-1.
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