Vibration isolation of washing machine for business applying Double-skyhook effect

Abstract

In late years production of commercial washing machines has been increasing. There is a problem with washing machines, eccentrics in a drum causes vibration, which leads to noise. In foregoing studies, an anti-vibration device has been utilized to damp vibration of washing machines. However, it is not enough to reduce the vibration. Washing machines therefore require a novel external vibration isolator. Also, the controlled object varies depending on the amount of washing clothes and washing mode and like. It is therefore important that the control device has robustness. In this study, we propose an external vibration isolator applying “Double-skyhook effect” for washing machines for business. We carried out simulations in order to demonstrate effects of the method. The most intense noise occur when the drum rotation speed is 11-20 Hz. We therefore check vibration isolation performance of 1120 Hz. A washing machine equipped with the proposed device was excited with chirp signal. The simulation revealed that the force acting on a floor was smaller than that of a conventional device by 60.6% in RMS. Also, even if the parameters fluctuated, the vibration isolation performance did not change. The results indicated that the proposed device was effective to damp the vibration and that the control device had robustness.