종-비틀림 컨버터를 이용한 회전형 초음파 모터에 관한 연구
(A) Study on the Rotary Type Ultrasonic Motor using a Longitudinal-Torsional Vibration Converter
종-비틀림 컨버터 회전형 초음파 모터;
- 원문 URL
On this paper, a rotary motor which has simple structure and high-torque was studied. For amplifying the longitudinal vibration of piezoelectric ceramic, the Langevin type vibrator was used. A stator of the motor was constructed by attaching the longitudinal-torsional vibration converter which has diagonal slits on the top of the Langevin type vibrator. A rotor was pressed by a spring on the driving surface of the stator. Using ANSYS 7.0 which is a finite element analysis program, the displacement changes of the driving surface of the stator depending on the slit's size and the materials of the stator were analyzed. Furthermore, these results were compared with driving characteristics of fabricated motor. As results of the analysis, a) The resonance frequency of piezoelectricity ceramics was 41.950[kHz]. b) Total length of the aluminum rod which is fit the resonance frequency of piezoelectricity ceramic was 32[mm]. c) Condition to obtain maximum displacement is when slit's length, width and depth were 4, 1 and 1[mm] respectively. d) According to material characteristics of stator, Magnesium presented the largest displacement, and in order of maximum displacement was stainless steel, titanium, aluminum and copper. According to the above results, stators of the motor were fabricated using aluminum and the driving characteristics were measured. As results of the experiments, a) The stator operated between 42.8~43.2[kHz] when input voltage was 60[Vrms]. b) Revolution speed and torque were increased whed the input voltage were increased. Revolution speed and torque were 33.3[rpm] and 160.1[mN·m] at input voltage was 65[Vrms]. c) Revolution speed was lineally decreased when the preload was increased. d) Maximum revolution speed was 33.3[rpm] at frequency of 42.9[kHz] with 65[Vrms]. And the maximum efficiency 1.14[%] is obtained at this condition with preload 540[gf]. From this study, it would be possible to make a ultrasonic motor which has a high-torque characteristic at low speed. Especially, the application using this simple structure and possibility of miniaturization is expected more than previous models.