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

As the standards of living improve, customers' demands for the quality of home appliances are continuously elevated and diversified. In laundry industries, those demands are mainly about the washing capacity, washing performance, and noise/vibration characteristics of home washers. Consequently, home appliance companies have been investing much of their resources to develop and manufacture washers which satisfy customers' demands. As a result, numerous home washers have been introduced in the global market and many researchers and engineers working at appliance companies are developing a brand-new washer at this very moment. Nowadays, even though the percentage of home washers installed near living spaces is increasing, the development of home washers having a big washing capacity has been stalled due to the limited form factor i.e. confined free space for washer installation. Moreover, the vibration problem caused by unbalanced laundry during the high-speed spinning course is now taken more seriously and draws much attention from users, as well as home appliance manufacturers. In this work, the innovative drum-type washer adapting fixed-tub structure was introduced and its design and analysis processes to minimize the vibration were described. Considering the limitation of the form factor given to the home washer, the structural features of the proposed fixed-tub system which will enable engineers and developers to maximize the washing capacity were shown. The proposed design expanded the washing capacity by 20%.

In order to suppress the unbalanced responses of driving parts the automatic ball balancer was introduced and designed. The automatic ball balancer is one of the most effective balancing devices where several balls inside a hollow rotor move automatically to eliminate vibrations in the rotational range higher than the major critical speed [1,2,3]. The basic principle of the dynamic stability of the ball balancer system was addressed [4] and ensured through finite element analysis to strengthen the rigidity of the driving parts. Along with the balancer, the optimization of rear gasket stiffness was carried out to enhance the transmissibility. The optimized gasket decreased the transmitted force by more than 30%. As a result, the vibration performance of the proposed washer was improved more than 50% compared to conventional washing machines.

1

S. Bae, J.M. Lee, Y.J. Kang, J.S. Kang, J.R. Yun, "Dynamic Analysis of an Automatic Washing Machine with a Hydraulic Balancer", Journal of Sound and Vibration, 257(1), 3-18, 2002. doi:10.1006/jsvi.2001.4162

2

J. Chung, D.S. Ro, "Dynamic Analysis of an Automatic Dynamic Balancer for Rotating Mechanisms", Journal of Sound and Vibration, 228(5), 1035-1056, 1999. doi:10.1006/jsvi.1999.2456

3

J. Chung, I. Jang, "Dynamic Response and Stability Analysis of an Automatic Ball Balancer for a Flexible Rotor", Journal of Sound and Vibration, 259(1), 31-43, 2003. doi:10.1006/jsvi.2002.5137

4

C.W. Lee, "Vibration Analysis of Rotors", Kluwer Academic Publishers, 1993.

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