Finite Element Analyses And Operating Characteristics Study On Ultrasonic Motor Driving Fluid Directly

The ultrasonic motor (USM) is a new type of motor, and its operation principle is different from electromagnetic motors. The energy transition is completed through the converse piezoelectric effect of piezoelectric material. Based on the contact pattern between the stator and rotor, USM is classified as contact type and non-contact type. The contact type USM, with the stator contacting the rotor directly, is characterized by large torque, low speed, low noise, quick response, and isn't disturbed by electromagnetic field. These characteristics make it promising in astronautics, robot, control system etc. At the same time, the contact type USM has some problems caused by friction, such as shorter life expectancy and continuous running time.The non-contact type USM, with the stator not contacting the rotor directly, resolves the shortages of contact type and becomes the new research direction in USM. The ultrasonic motor fluid driven directly is introduced in the paper. The inside of the stator is filled with fluid. The rotor is fixed by the axial in the fluid. The energy produced by the piezoelectric vibration is transferred from the stator to the rotor through the fluid medium, which rotates the rotor. Varying the fluid medium, the different speed characteristics can be obtained.The major research work and achievements obtained in this paper are outlined as follows:(1) The basic structure and operating principle of the USM fluid driven directly are introduced. The formation of the standing wave and the combination of the traveling wave are deduced. The process of energy transmission and the acoustic streaming field in the fluid are analyzed theoretically.(2) Based on the structure and operating principle of the USM, a finite element analysis (FEA) method is advanced to analyze the stator vibration characteristic. The stator vibration modal, resonant frequency, vibration amplitude, vibration traces and the influence of the external exciting method on the stator vibration are researched. The load effect of fluid medium is analyzed according to the coupling equation between the sound field and the stator.(3) The simulation of the acoustic streaming field is solved by combining the nonlinear sound field analysis, driving force computation and fluid dynamic analysis. The affects on the acoustic streaming driving force and acoustic streaming velocity of...