Keywords: drum type washer, washing capacity, fixed-tub, automatic ball balancer, dynamic simulation.

Recently, customers demand higher quality home appliances as their standards of living improve. The main issues for washing machines are energy saving, ease of use, noise and vibration, washing capacity and washing performance. Globally, the washing machine size tends to increase because the capacity of a washing machine is strongly related to energy saving and ease of use. But the limitation on space makes it hard to increase the washing capacity. Consequently, home appliance companies have been investing much of their resources in the development of home washers that have a bigger washing capacity within the confined size of the washer. As a result, LG electronics released an innovative drum type home washer adapting a fixed-tub structure, which increases the washing capacity by 20%.

Home washers can be categorized as drum type, agitator type and pulsator type. Among these washer types, the drum-type washing machines recently became popular because the damage to the laundry is relatively low and it uses less water than other types, even though it creates more floor vibration. Because the percentage of home washers installed near living spaces is increasing these days, customers take the vibration problems more seriously than ever. Vibration is usually caused by unbalanced laundry during the dehydration course. Some home appliance manufacturers are adapting an automatic ball balancer to cancel out the unbalanced mass to suppress the vibration and noise of washers.

An automatic ball balancer (ABB) is a device to automatically eliminate the variable imbalance of rotating mechanisms such as washing machines and optical disk drives. The studies of ABBs are mainly focused on academic research, and it is difficult to find results applied to practical models.

In this study, the main interesting features of washers having an ABB are introduced and analyzed. To determine the behaviour and to extract the properties of an ABB, some experiments have been done. A new ABB model is introduced considering the rolling motion of the balls and geometrical imperfections. This ABB model guarantees a high speed simulation because a ball needs only one degree of freedom when applied to the dynamic simulation for fixed-tub type washers. The DADS software which has been one of the most popular dynamic tools, is used here for the dynamic simulation. The simulation results show good agreement with the experimental ones.

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