Patent Publication Number: US-2011047713-A1

Title: Method of treating laundry

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Korean Patent Application No. 10-2009-0071051 filed on Jul. 31, 2009, Korean Patent Application No. 10-2009-0103741 filed on Oct. 29, 2009 in the Korean Intellectual Property Office, and U.S. Provisional Patent Application No. 61/230,616 filed on Jul. 31, 2009 in the USPTO, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This disclosure is directed to a method of treating laundry, and more specifically, to a method of treating laundry that firstly perform a washing cycle using hot water having a good washing effect on the laundry, and then, adds cold water to secondly perform a washing cycle using the added cold water, thereby improving the washing efficiency for the laundry as well as minimizing the usage of detergent. 
     2. Discussion of the Related Art 
     A process of treating laundry by a washing machine that treats laundry to remove unwanted materials from the laundry generally includes a process of mixing a detergent with wash water, a process of performing a washing cycle on the laundry using the wash water mixed with the detergent, a process of supplying wash water that does not include detergent to a washing tub to rinse the laundry, and a process of dehydrating the laundry that was completely laundered. Further, the washing machine may further perform a process of drying and ironing the laundry to remove the water from the laundry. However, a process of treating laundry basically includes a detergent mixing process, a washing process, a rinsing process, and a dehydrating process. 
     The performance of a washing machine may be determined depending on how much unwanted material may be removed from the laundry by the washing machine, or how much detergent is needed to detach the unwanted material from the laundry. 
     When the washability of the washing machine is not satisfactory, a user generally tends to increase the amount of detergent to raise the washability. However, the washability does not linearly increase in proportion to the amount of detergent. Rather, it may cause unnecessary consumption of detergent. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the present invention provide a method of treating laundry that improves washability for laundry without increasing detergent or wash water that is supplied to a washing tub. 
     According to an embodiment of the present invention, there is provided a method of treating laundry comprising a first laundry treating step of supplying first wash water having a temperature higher than a user&#39;s setup temperature to a washing tub to perform a washing cycle on the laundry, and a second laundry treating step of additionally supplying second wash water having a temperature lower than the user&#39;s setup temperature to the washing tub to perform a second washing cycle on the laundry, wherein when the first wash water and the second wash water are mixed in the washing tub, a temperature of the mixed wash water in the washing tub is equal to the user&#39;s setup temperature. 
     The method of treating the laundry as described above may improve washability of the washing machine without excessively supplying detergent, as well as increase washing effects by the wash water while maintaining the temperature of wash water to the user&#39;s setup temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a washing machine according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 . 
         FIG. 3  is a block diagram illustrating control flow of the washing machine shown in  FIG. 1 . 
         FIG. 4  is a flowchart illustrating a method of treating laundry by a washing machine according to an embodiment of the present invention. 
         FIG. 5  is a graph illustrating a relationship between the temperature of wash water and washability. 
         FIG. 6  is a graph illustrating a process of supplying the first wash water to the washing tub and a process of supplying the second wash water to the washing tub when it is assumed that the amount of water that may be stored in the washing tub is 80 liters. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view illustrating a washing machine  100  according to an embodiment of the present invention, and  FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the washing machine  100  includes a cabinet  110 , a water container  125  that is arranged in the cabinet  110  to contain wash water, a washing tub  122  that is arranged in the water container  125  to contain laundry, a driving unit  170  that transfers a driving force to the washing tub  122  to repeatedly rotate the washing tub  122  in alternating directions or in a single direction, a drainage unit  150  that discharges wash water from the water container  125  to the outside, and a wash supply unit  120  that is provided at a side of the cabinet  110  to supply wash water to the water container  125  and the washing tub  122  from an external source (not shown). 
     The cabinet  110  includes a cabinet body  111  having an opening, a base (not shown) that is connected to the cabinet body  111  under the cabinet body  111 , a cover (not shown) that is connected to the opening, and a control panel  126  that is provided at a side of the cover and connected to the cabinet body  111 . The cover includes a door  123  that is rotatably connected to the cover to open and close the opening. The control panel  126  includes an input unit  116  that allows a user to enter an input signal from an external source (not shown). 
       FIG. 3  is a block diagram illustrating control flow of the washing machine  100  shown in  FIG. 1 , and  FIG. 4  is a flowchart illustrating a method of treating laundry by a washing machine according to an embodiment of the present invention. 
     Referring to  FIGS. 3 and 4 , a user puts laundry in the washing tub  122  and enters a washing cycle through the input unit  116  (S 201 ). When the washing cycle is entered, a controller  190  determines the amount of wash water, the amount of detergent, a time during which the washing tub rotates, and a rotating method of the washing tub  122  depending on the washing cycle. And, according to the determined conditions, the controller  190  sequentially supplies the detergent and water to the washing tub  122  (“first water supply”) (S 202 ). 
     The controller  190  controls the wash supply unit  120  to supply the washing tub with first wash water that has a temperature higher than a user&#39;s setup temperature. For example, when the user&#39;s setup temperature is 30° C., the temperature of the first wash water may range from 35° C. to 40° C. 
     The amount of the first wash water supplied to the washing tub  122  may be, for example, ¼ to ¾ of the overall amount of water that may be stored in the washing tub  122 . The (overall) amount of water that may be stored in the washing tub  122  may be referred to as a “water storage capacity” throughout the specification. 
     Also, a ratio of hot water to cold water in the first wash water may be, but not limited to, 1:1 to 3:1. 
     According to an embodiment, the first wash water may be obtained by mixing hot water with cold water. As the amount of hot water used in the first wash water increases, the first wash water may have a higher temperature than the user&#39;s setup temperature. Accordingly, the temperature of the wash water obtained by mixing the first wash water with second wash water may be equal or similar to the user&#39;s setup temperature of the wash water. 
     In a washing method according to an embodiment of the present invention, a washing cycle is performed according to a user&#39;s setup temperature unlike a method of simply washing laundry using hot wash water. Further, wash water supplied to the washing tub  122  is divided into first wash water and second wash water, wherein the first wash water is supplied earlier than the second wash water, and the temperature of the first wash water is set to be relatively higher than a user&#39;s setup temperature, thereby increasing the washing efficiency and energy efficiency as well as saving detergent consumption. 
     Further, in the washing method according to an embodiment of the present invention, the second wash water is added to the washing tub  122  after the temperature of the first wash water is increased to raise the washing efficiency, thereby further improving the washing efficiency. 
     Next, according to the washing cycle, the controller  190  controls the driving unit  170  to rotate the washing tub  122  and washes the laundry using rotation of the washing tub  122  (S 203 ). 
     The controller  190  may rotate the washing tub  122  or a pulsator  140  to wash the laundry. To effectively clean the laundry contained in the washing tub  122 , the controller  190  may rotate the washing tub  122  or the pulsator  140  in a single direction or alternately in a first direction and a second direction. Further, the controller  190  may also properly mix the laundry with the detergent by forcibly rotating the pulsator  140  in the first direction to generate a climbing water current and dropping the climbing water current from an upper portion of the washing tub  122  towards the laundry. 
     The amount of the first wash water supplied to the washing tub  122  is smaller than the overall amount of water that may be stored in the washing tub  122 . Since the first wash water is not fully filled in the washing tub  122 , the amount of the detergent supplied to the washing tub  122  may be similar (or equal) to or smaller than the amount of detergent that would be supplied to the washing tub  122  when the washing tub  122  is fully filled with wash water. 
     The first wash water having a temperature higher than the user&#39;s setup temperature may further activate the detergent supplied to the washing tub  122  and facilitate removal of unwanted material from the laundry. The higher the temperature of the first wash water is, the more similar effects to those obtainable by boiling the laundry may be achieved. Further, not fully filling the washing tub  122  with the wash water reduces the load on the driving unit  170  driving the washing tub  122 . 
     After completion of the first washing cycle using the first wash water and detergent, the controller  190  secondarily supplies wash water to the washing tub  122  that is filled with the first wash water, detergent, and laundry (S 204 ). 
     Unlike the first wash water, the wash water secondarily supplied (hereinafter, referred to as “second wash water”) may be cold water that has a temperature lower than the user&#39;s setup temperature. The second wash water is additively supplied to the washing tub  122  after the laundry is washed to a certain extent by the first washing cycle. The second wash water increases the amount of wash water in the washing tub  122  to improve the efficiency of washing the laundry. 
     Next, based on the washing cycle, the controller  190  controls the driving unit  170  to perform a second washing cycle on the washing tub  122  containing the first wash water primarily supplied, the detergent, the laundry, and the second wash water secondarily supplied (S 205 ). The first wash water, the detergent, the laundry, and the second wash water may be mingled together in the washing tub  122  during the second washing cycle. And, the second washing cycle may be performed with a sufficient amount of wash water in the washing tub  122 . 
     The first washing cycle primarily removes unwanted material from the laundry using hot water, and the second washing cycle secondarily removes the remaining unwanted material from the laundry using the sufficient wash water. Accordingly, the method of treating the laundry according to an embodiment of the present invention, may provide better washing effects than a method of washing laundry using wash water having a constant temperature set by a user. 
     Next, after the second washing cycle is complete, the controller  190  controls the drainage unit  150  to discharge the wash water from the washing tub  122  (S 206 ). If the washing machine  100  has a function of drying or ironing the laundry, the controller  190  may also perform additional cycles, such as drying or ironing the laundry, after draining the washing tub  122 . 
       FIG. 5  is a graph illustrating a relationship between the temperature of wash water and washability. 
     Referring to  FIG. 5 , it can be seen that as the temperature of the wash water increases, the washability also increases. Further, it can also be seen that as a time during which the laundry is washed in the washing tub  122  increases, the washability increases correspondingly. A significant improvement in washability may be expected only by increasing the temperature of wash water. For example, as shown in  FIG. 5 , as the temperature of the wash water increases by 10° C., for example, from 30° C. to 40° C., the washability may increase by 5%. Also, it can be seen that there is a significant difference in washability between when the temperature of wash water is less than 25° C. and when the temperature of wash water is equal to or more than 30° C. 
     However, an increase in the temperature of wash water to a high temperature, such as 90° C. or higher, or an increase in the washing time may lead to waste of hot water and inefficient time consumption since the washability does not increase in proportion to the washing time and the temperature of wash water. 
     Referring to  FIG. 5 , a difference in washability still exists between when a washing cycle is performed using wash water of 40° C. or more for 40 minutes and when a washing cycle is performed using wash water of 90° C. or more for 70 minutes. However, the latter is not very efficient considering energy efficiency according to the washing time and the amount of hot water. 
       FIG. 6  is a graph illustrating a process of supplying the first wash water to the washing tub  122  and a process of supplying the second wash water to the washing tub  122  when it is assumed that the water storage capacity of the washing tub  122  is 80 liters. 
     Referring to  FIG. 6 , the controller  190  supplies about 60 liters of first wash water to the washing tub  122  during the first water supply. Among them, 37 liters of water is supplied as hot water and 23 liters of water is supplied as cold water, so that the overall temperature of the first wash water is set to a temperature of hot water. 
     Although it is described in  FIG. 6  that mixed water (first wash water) of hot water and cold water is primarily supplied to the washing tub  122  to raise washing efficiency while minimizing usage of hot water, 60 liters of hot water may be only supplied to the washing tub  122  as the first wash water, as well. The temperature of the first wash water primarily supplied may be higher than a user&#39;s setup temperature of wash water or temperature of the second wash water. 
     After the hot water is primarily supplied to the washing tub  122 , the controller  190  controls the driving unit  170  to rotate the washing tub  122  or the pulsator  140  and resultantly the laundry during a predetermined time by a washing cycle. 
     For example, the washing tub  122  may be rotated alternately in clockwise and counterclockwise directions. The controller  190  controls the driving unit  170  so that the laundry performs alternate rotation in the washing tub  122  during a time according to the washing cycle (4.5 minutes) and then secondarily supplies wash water to the washing tub  122 . 
     Since the washability on the laundry increases as the temperature of wash water, the washing time, and the amount of laundry increase, the controller  190  increases the amount of wash water by supplying the washing tub  122  with the second wash water colder than the first wash water after the laundry has been washed to a certain extent by the first wash water that was primarily supplied to the washing tub  122 . Assuming the water storage capacity of the washing tub  122  is 80 liters, the amount of wash water as added is on the order of 20 liters. Some of unwanted materials have been already removed from the laundry by the first wash water. The second wash water further supplied to the washing tub  122  may increase the overall amount of wash water to further improve the washability. 
     After the second wash water is supplied to the washing tub  122 , the controller  190  controls the driving unit  170  to rotate the washing tub  122  or the pulsator  140 , thus performing another washing cycle. 
     The invention has been explained above with reference to exemplary embodiments. It will be evident to those skilled in the art that various modifications may be made thereto without departing from the broader spirit and scope of the invention. Further, although the invention has been described in the context its implementation in particular environments and for particular applications, those skilled in the art will recognize that the present invention&#39;s usefulness is not limited thereto and that the invention can be beneficially utilized in any number of environments and implementations. The foregoing description and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.