Vibration Analysis of the Self-Excited Vibration in the Rotor System Due to Ball Balancer

The ball balancer has been used as the vibration suppression device in rotor system. It has a superior characteristic that the vibration amplitude is reduced to zero at the rotational speed range higher than the major critical speed. However, the ball balancer may cause a self-excited vibration when the balls rotate in the balancer, and this self-excited vibration results in the large amplitude vibration. In this paper, the occurrence region and vibration characteristics of the self-excited vibration are investigated. The theoretical analysis is performed and a set of the fundamental equations governing the self-excited vibration is obtained. The influences of the parameters, such as, damping of the ball motion, ball mass, and radius of the ball orbit are explained. As the result, it is shown that the damping of the ball motion and the ball mass have the effect on decreasing the occurrence region of the self-excited vibration.