A cylindrical standing wave ultrasonic motor using bending vibration transducer

► The bending vibration of the cylindrical stator is excited by a bending transducer. ► The vibration trajectories of the driving teeth are oblique ellipses. ► The vibration test result is in good agreement with the FEM analysis result. ► Typical output of the motor is no-load speed of 165 rpm and maximum torque of 0.45 N m. A cylindrical standing wave ultrasonic motor using bending vibration transducer was proposed in this paper. The proposed stator contains a cylinder and a bending vibration transducer. The two combining sites between the cylinder and the transducer locate at the adjacent wave loops of bending vibration of the transducer and have a distance that equal to the half wave length of bending standing wave excited in the cylinder. Thus, the bending mode of the cylinder can be excited by the bending vibration of the transducer. Two circular cone type rotors are pressed in contact to the end rims of the teeth, and the preload between the rotors and stator is accomplished by a spring and nut system. The working principle of the proposed motor was analyzed. The motion trajectories of teeth were deduced. The stator was designed and analyzed with FEM. A prototype motor was fabricated and measured. Typical output of the prototype is no-load speed of 165 rpm and maximum torque of 0.45 N m at an exciting voltage of 200 V rms.