Study And Analysis On Characteristics And Driving System Of The Ultrasonic Motor Driving Fluid Directly

Non-contact type ultrasonic motor in which the stator and the rotor do not contactdirectly is a new research direction in the field of ultrasonic motor. Not depending onthe friction force, it solves many problems of contact type ultrasonic motor, such asshorter life expectance and continuous running time. New type non-contact ultrasonic motor, in whichthe rotor of the motor swim influid, was introduced in this paper. The energy produced by the piezoelectric vibrationis transferred from the stator to the rotor through the fluid medium. The non-contactultrasonic motor with fluid medium is analyzed in detail in this paper as follows. At first, the working mechanism of this motor are proposed. The uniqueconstruction of the motor is analyzed in detail, the principle of the production of thevibration, the formation of the standing wave, the combination of the traveling waveand the process of energy transmission in the fluid are discussed. Then the relationship between the fluid revolution speed and driving frequency isgiven by experiments. Within some given range, the higher the vibration velocity ofstator is, the faster the fluid revolution speed we can observe. Also, the flow of thefluid reaches saturation when the stator vibration is too high. Based on theoreticalanalyses and experiments, it is clear that the nonlinearity of the acoustic field in thefluid is the main cause of the saturation of the fluid revolution speed. Next, the results of experiments aimed at optimizing this motor are presented.The acoustic streaming velocity of the motor can be increased by using the resonanceof the fluid confined in the ring stator, employing a higher mode of stator vibration,and increasing the roughness of the stator wall. At last, a driving circuit for the motor is designed according to its peculiarity,where a signal whose frequency is adjustable is generated by the self excitedoscillation, then the signal is shifted in phase, so four sets of square-wave signals thatdiffer 90 degrees in succession are generated, which can be applied to drive two setsof push-pull main circuits. Four input signals of the motor are obtained throughexperiments. And the driving frequency and voltage is easy to regulate. So this circuitmeets the requirement of the most experimentation very well.