Takayuki Tsukimoto

Finite-element analysis of the rotor/stator contact in a ring-type ultrasonic motor

A way to understand mechanical characteristics of an ultrasonic motor is presented. First, the vibration mode of a stator is calculated using a finite-element method (FEM) code. The path of the elliptic motion of the stators teeth is obtained. The computed vibration mode at the surface of the stator is compared with that measured by an electrooptical displacement transducer. Next, the contact condition of the rotor/stator is calculated. The displacement and velocity of the rotor/stator, the distortion of the stick/slip area, the rotational speed of the rotor, and the friction loss of the motor are obtained. The calculated rotor displacement and torque-rotational speed curve correspond closely to the experimentally measured ones. The internal loss of the rotor/stator and the loss of the supporting felt are measured. The total loss of these losses and the calculated friction loss agree with the measured total loss. The calculated and the measured efficiency of the motor also agree.<<ETX>>

The contact mechanism of an ultrasonic motor

The mechanical characteristics of a ring-type ultrasonic motor are clarified. The finite-element method (FEM, MSC/NASTRAN) was used to obtain the shape of the elliptic motion at the surface point of projections. The vibration mode of projections was measured by using an electrooptical displacement transducer made by Zimmer KG. The accuracy of the simulation was confirmed by comparing the calculated results with the measured results. The dynamic contact condition of a stator and a rotor was calculated by using the FEM (JNIKE3D). The simulated displacements, T-N (torque-rotating-speed) curve, loss power and efficiency are compared with the experimental results.<<ETX>>