No abstract

This paper presents a symmetric hybrid transducer ultrasonic motor designed to produce large longitudinal vibration stress in the rotor/stator contact interface for high-torque operation. The nodal plane of the longitudinal vibration mode was adjusted to match the rotor/stator contact interface, and the piezoelectric ceramic disks for the longitudinal vibration were installed at the nodal plane of the longitudinal vibration mode for effective excitation. An experimental motor, 20 mm in diameter, using the first torsional vibration mode and the second longitudinal vibration mode was manufactured. A maximum torque of 0.8 N.m was achieved in the prototype, an improvement over previous versions.

A large hybrid transducer type ultrasonic motor has been studied for the purpose of achieving large output torque. The goal of our research is to realize a megatorque (i.e., 1000 kgf·cm) ultrasonic motor. The key to accomplishing this goal lies in obtaining sufficient longitudinal vibration in order to control the frictional force between the rotor and the stator. In this paper, a motor of 120 mm in diameter using the second longitudinal vibration mode is fabricated and investigated, as a preliminary step toward realization of the megatorque ultrasonic motor. As a result of our experiments, the maximum torque of 400 kgf·cm was achieved.

“Girigiri-Garigari” is the Japanese name of a scientific toy which consists of a square rod and a propeller. The wooden rod has several notches along its long edge, and the propeller is loosely attached to one end of the rod by a nail. The propeller is rotated by rubbing the rod with another bar. A player can control the revolution direction of the propeller in two ways, by changing the gripping position or condition of the rod. This paper presents an experimental study on the mechanism of this toy. Main results of this study are that the revolution of the propeller is caused by the elliptical motion excited at the end of the rod, and that the vibration system can be represented by a lumped-constants model. Then, we reveal the mechanism of how the elliptical motion is generated by the player's operations.

A noncontact transport experiment in water using ultrasonic traveling waves was investigated. Acrylic, aluminum, and brass discs were used as test objects. Traveling waves were generated using two ultrasonic transducers attached at the ends of a vibrating plate. One side was used as the wave-source side and the other side was used as the wave-receiving side. Acrylic plates cemented to the sides of the vibrating plate formed a tank to hold water. Object transportation was accomplished by adding a small amount of water to the vibrating structure. The transport velocity of floating objects in water is faster than for floating transport in air because of buoyancy. The transport velocity of an object depends on water height. The minimum value of the velocity occurs when the disc thickness is equal to the water height. The transport velocity increases as the height of water increases. For very shallow depths, the largest velocity is obtained when cavitation-induced streaming occurs.