Abstract
In this study, driving a fan by a thin-disk shaft-driving type ultrasonic actuator is presented. Shaft-driving modes are designed by changing the geometric shape of a thin-disk vibrator. They are analyzed by finite element method to figure out suitable geometric parameters to construct a new ultrasonic actuator. The driving joint is also well devised to promote the energy transfer from stator to fan rotor. The proposed 3LL-modal actuator is constructed by a thin-disk vibrator (piezo buzzer element) with three same deep-depth notches, arranged in 110°-120°-130° along the border of the vibrator, and with a driving bolt fastened at vibrator’s center. With three same deep-depth notches, the boundary of the vibrator can be released and the inner deformed height can be increased. Furthermore, by arranging notches in an asymmetric distribution, the inner deformed height can thus be enhanced further in a specific direction. Accordingly, the fan can be spinning quickly upon the driving bolt by the 3LL-modal actuator. The driving joint’s design involves the driving contact, the length of driving bolt, and the length between actuator and base plate. Among them, the driving contact’s design referring to the contact ring’s diameter and the end shaft’s radius affects crucially the transferred energy from stator to rotor. Experiential results show that a fan blade with 75 mm diameter can be rotated up to 2250 rpm consumed about 1.1 W by the 3LL-modal actuator. Under the same blade and rotating speed, the power consumption of the DC motor is 1.8 W. Therefore, the proposed ultrasonic actuator demonstrates the ability to substitute for a DC fan motor and the potential to compete in thin-fan market.