Vertical And Torsional Ultrasonic Motor Of Basic Research

The ultrasonic motor(USM) is a new type of motor which developed from the 20th century 80 years. It take advantage of the converse piezoelectric effect of the piezoelectric, which make the stator vibrated in the ultrasonic frequency. And the vibration was converted into the rotor movement which produce torque,output power and driver through the friction between the stator and the rotor. It is a more mature kind in the study of new micro-motor. It can satisfy people's demands of micro-motor. It has many benefits such as small size,light weight,compact structure,low noise and no electromagnetic interference, therefore it developed faster and increasingly wide range of applications.Longitudinal-Torsional ultrasonic motor is an important type of Ultrasonic Motor. It attracts people's attention because its high output power,convenient controllability,consistent of positive ture and contrary ture. It take advantage of the longitudinal vibration and the torsional vibration of the stator, the coupling of the two vibration make the stator generate elliptical motion. Then drive the rotor rotated through the friction between the stator and rotor. Compared with the traveling wave-type ultrasonic motor, the rotor's normal and tangential vibration of the longitudinal-Torsional ultrasonic motor can excited by longitudinal and torsional piezoelectric respectively. So we can change the size of input voltage of the vertical and the torsional, facilitate the motor's mechanical output characteristics. Longitudinal-Torsional ultrasonic motor was used broadly, it can be used in robots,cars,household appliances,positioning devices,spacecraft and other areas, especially some areas such as need for high torque. This thesis study several methods of Longitudinal-Torsional ultrasonic motor frequency degeneracy. The major research are as follows.(1) Analysis the exposure of the stator and rotor through the elliptical trajectories excited by ultrasound. Calculate the drive torque and braking torque generated by the contact surface of stator and rotor under different pressure. Discusses the analysis of friction during the operation according to the amended adhesion theory. It has guiding significance to improve the mortor's reliability,stability. The problems which grasps the impact factors of driving torque and choose the stator and rotor's surface materials shoud be considered. Established the equivalent circuit model, The mechanism of the formation of elliptical motion and the driver and loss produced by the friction between the stator and the rotor can be well reflected by the equivalent circuit model.(2):Establish the mathematical model of the equivalent four-terminal network of Longitudinal-Torsional ultrasonic motor through manson electro-mechanical equivalent circuit. Calculate the thin rod vibration-the quality of match,the thin rod vibration-the quality of match with the exponential transition and with an additional side of the exponential case according to four-terminal network transfer matrix method. When using the thin rod vibration-the quality of match with the exponential transition, the change of the longitudinal and torsional vibration is more sensitive to change the length of trough. When using the additional end of the exponential, it only when the end of the radius of r1=0.005m,we can approximate the longitudinal frequency and torsional frequency. Last, comparated to the result of ANSYS's calculations, the radius of the middle section shoud not be choosed too small, and the transition sectionpshoud not be choosed too much.