Textiles: fluid treating apparatus – Machines – Single tub and automatic sequential operation mechanism
Reexamination Certificate
2000-12-12
2003-01-28
Coe, Philip (Department: 1746)
Textiles: fluid treating apparatus
Machines
Single tub and automatic sequential operation mechanism
C068S023200, C074S573110
Reexamination Certificate
active
06510715
ABSTRACT:
A rotor, drum or similar system, rotating along one axis is usually a very important part of many machines. Such similar rotational parts exists in electric motors, various mills, fans, turbines, grinding machines, washing machines and many similar machines. In many machines, the balance is provided by adjusting the uniformity of the weight distribution of these rotational bodies along their rotational axis during manufacturing, where otherwise such an unbalance may cause unwanted vibrations in the machine which can even cause damage. But in some cases, the rotating part of the machine can be under the influence of varying imbalance forces. A washing machine spinning at high speeds, a grinding machine with worn out grind stone, a mill with unevenly worn parts are some examples of such machines. The said invention of the smart balancing system brings effective solution for such imbalance problems faced in these machines. A washing machine is chosen as an example in order to explain the said invention. The application of this invention for other machines will be similar to various washing machine types described below and therefore not explained in detail in this description.
In our present time, automatic washing machines are in use at homes, touristic locations, hospitals, residence homes, military organisations, organisations which provide professional cleaning services and many other areas. Besides the use of these machines for cleaning purposes, the use of such machines are continuously increasing in the textile industry for garment washing, stone washing and garment dying processes. Due to increasing capacities in the cleaning and textile industries, the number of machines to be used per unit area tends to increase and this encourages the washing machine manufacturers to design and manufacture larger capacity machines. Larger machines mean larger front loading doors and larger diameter wash drums. The larger diameter drums, spinning at high speeds creates new problems to be solved. Today, various washing machines are produced ranging from 4-6 Kg used in our homes, 6-150 Kg used in professional cleaning services and 100-500 Kg used in textile industry which are bedded with shafts either from one end or both ends of the rotating drum.
In rotary drum washing machines, high spin speeds are usually required in order to achieve efficient spinning results at around 300-400 g centrifugal forces. The factors which affect water extraction from garments in centrifugal spinning method are; drum diameter, drum rotation speed, the permeability and the temperature of the garments and the thickness of garments on the perforated surface of the drum. Efficiency in extracting water is not directly proportional with the increased centrifugal forces due to higher drum rotation speeds. Increasing centrifugal forces, on one hand, forces the mass of water towards the drum circumference but at the same time, it squeezes all the garments along the drum's inner surface and these wet textile fibres under this force forms a plastic type layer causing resistance against extracted water. It is more efficient to increase the inner drum surface area as this will reduce the garment thickness along the drum surface, causing better extraction. Increasing the inner drum surface usually results in deeper drum depths over longer rotational axis. The increased drum length makes it more difficult for the garments to be equally distributed against the inner drum surface which causes high imbalance along the rotational axis of the drum. Even if this is achieved, very small differences in weight distribution along the rotational axis causes damaging vibrations at high spin speeds. This imbalance problem is the major design criteria in high spin speed washing machines. Today's classic systems employs techniques where the drum assembly is placed on springs or air cushions and uses air or hydraulic type pressurised cylinders or shock absorbers in order to minimise the effects of vibration on the main body structure.
Another method of reducing the effects of vibration is to increase the weight of the mass, under the effects of acting imbalance forces. As a result, the mass which the imbalance forces has to move is increased, reducing the magnitude of vibration. This requires the use of additional weights on the total construction of the washing machine. These additional weights on the machine usually exceeds 50% of the normally required mechanical construction weight of the machine. Apart from this, the bearings used in order to connect this heavy mass of rotating mechanism to the main body construction has to be chosen larger than it should be necessary due to the high vibrational forces caused by the imbalance of the rotational system.
The vibration absorption systems used on the existing machines have limited use. By this reason, the garments have to be distributed along the inner drum surface as good as possible before the extraction process. In order to achieve this, the drum rotation speed first has to be increased to a level where the centrifugal forces just start to overcome the earth's gravitational forces. During this constant rotational speed or speed increase, the garments near to the inner surface of the drum sticks to the inner surface and starts to rotate together with the drum. As the garments, which cling to the drum as a result of the centrifugal forces stars to get pressed towards the inner surface, the cling diameter will be reduced gradually. When all the garments sticks to the inner surface and starts rotating with the drum, the distribution is said to be completed. If the garment distribution is not achieved properly, the extraction process will halt during spin process due to unacceptable vibration levels of the machine and the distribution process will commence again. These “re-starts” cause loss of time and energy as well as reduction in the machine capacity.
BACKGROUND OF THE INVENTION
Many balancing techniques have been developed so far for washing machines, in order to eliminate the unwanted inbalance forces. These are generally mechanical systems which make use of the acting imbalance forces. These systems introduced some improvements in small capacity machines but due to their complex construction, they required maintenance and increased the over all cost of the machine and therefore not widely used. The said mechanical balancing systems weren't also successfully applied for higher capacity industrial washing machines. U.S. Pat. No. 2,534,267/268/269, Kahn, U.S. Pat. No. 3,117,962, Starr's patents are some examples for the said balancing systems. The U.S. Pat. No. 5,280,660 Pellerin-Gaulter patent, which is most similar to the said invention in theory, has benefited from the ribs inside the rotating drum and tried to eliminate the imbalance forces by forcing water into these ribs through separate channels. This method divides the 360° of drum circumference into three locations with 120° apart and forces the correct amount of water into one or more ribs opposite to the imbalance force vector until this vector is eliminated. This balancing system has, to a great amount, solved the balancing problems in the larger industrial type washing machines and with the additional precautions, high speed spinning was achieved. But with this method, it was impossible to eliminate the balancing weights completely. The generated imbalance vectors can be at different points along the drum axis and the magnitude and direction can also vary. For drums with small depth/diameter ratio, the above mentioned method could provide satisfactory results but as the depth of the drum is increased, the imbalance becomes almost impossible to be compensated with the said method. Besides, the dynamic movements of the balancing fluid in the ribs itself causes varying imbalance weights in the system. With this method, the rotational axis of the drum must be highly horizontal. If this condition is not satisfied, the balancing fluid in the ribs will tend to collect to one side along the rotational axis
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