Patent Publication Number: US-2011072861-A1

Title: Washing Machine and Steam Washing Method Thereof

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 12/126,339 filed May 23, 2008, claiming priority to Korean Patent Application No. 10-2007-0051062 filed May 25, 2007; and Korean Patent Application No. 10-2007-0051063 filed May 25, 2007, the contents of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a washing machine, and more particularly to a washing machine and steam washing method thereof that washes laundry with steam generated by heating wash water with a wash heater. 
     2. Description of the Related Art 
     Generally, a washing machine includes a cabinet, a tub adapted to contain wash water, a drum disposed inside the tub, a drive motor adapted to drive the drum, a water supply valve connected to the tub to supply wash water to the tub, and a detergent container connected to the water supply valve and containing detergent. Additionally, the washing machine includes a drain unit extending from the tub to the outside of the cabinet, a steam generator disposed between the water supply valve and the detergent container, and a steam heater provided to the steam generator to generate steam by heating wash water. 
     The washing machine performs steam washing as follows. 
     First, water is supplied into the steam generator and heated by the steam heater provided to the steam generator to supply steam into the drum where laundry has been received. While steam is generated by the steam heater, the drive motor rotates the drum in the forward and reverse directions to agitate the laundry inside the drum for steam washing. During the steam washing, the steam generated by means of the steam heater sterilizes bacteria and fungi in the laundry. During a washing cycle after completion of the steam washing operation, a wash heater can be operated to heat wash water inside the tub or the steam heater can be operated to supply steam into the tub. 
     However, the washing method of the conventional washing machine entails substantial power consumption since the steam heater is continuously operated from start to end of the washing operation to supply steam to the laundry. Moreover, in the conventional washing machine, since washing and rinsing cycles are carried out after the steam washing, bacteria or fungi can be attached to the laundry during the washing and rinsing cycles, thereby deteriorating sterilizing effects of the steam washing. 
     SUMMARY OF THE INVENTION 
     The present invention is conceived to solve the problems of the conventional techniques as described above, and an aspect of the present invention is to provide a washing machine and steam washing method thereof that supply steam to laundry to perform steam washing after completion of a spin-dry cycle. 
     In accordance with one aspect of the present invention, there is provided a steam washing method of a washing machine including: performing primary steam washing by supplying steam to laundry; performing a washing cycle by supplying wash water to the laundry; performing a rinsing cycle; performing a spin-dry cycle to remove the wash water from the laundry; and performing secondary steam washing by supplying steam to the laundry. Preferably, the performing of the primary and secondary steam washing comprises supplying wash water for steam, and generating the steam while alternately rotating a drum in forward and reverse directions by operating a wash heater and a motor. Preferably, when supplying the wash water for steam, the wash water for steam is supplied through an assistant water supply tube so as to prevent the wash water for steam from being absorbed by the laundry. 
     In accordance with another aspect of the present invention, there is provided a steam washing method of a washing machine including: performing primary steam washing by supplying steam to laundry; performing a washing cycle by supplying wash water to the laundry; performing an initial rinsing cycle; performing secondary steam washing by supplying steam to the laundry; performing a final rinsing cycle; and performing a spin-dry cycle to remove the wash water from the laundry. Preferably, the performing of the primary and secondary steam washing comprises supplying wash water for steam, and generating the steam while driving a drum by operating a wash heater and a motor. 
     In accordance with a further aspect of the present invention, there is provided a washing machine including: a water supply tube supplying wash water to a tub; a heater compartment to contain the wash water; a wash heater heating the wash water contained in the heater compartment to generate steam; and a level detection sensor detecting a level of the wash water contained in the heater compartment. The washing machine may further include a gasket disposed at one side of the tub; a drum disposed inside the tub to receive laundry; and an assistant water supply tube passing through the gasket to prevent wash water for steam from being supplied to the laundry. Preferably, the assistant water supply tube communicates with the water supply tube. Preferably, the washing machine further includes a water supply valve between the assistant water supply tube and the water supply tube. Preferably, the heater compartment extends outwardly from the tub. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become apparent from the following description of exemplary embodiments given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a washing machine according to one embodiment of the present invention; 
         FIG. 2  is a block diagram of the washing machine according to the embodiment of the present invention; 
         FIG. 3  is a flowchart of a steam washing method of a washing machine according to one embodiment of the present invention; and 
         FIG. 4  is a flowchart of a steam washing method of a washing machine according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Herein, terms should be defined in consideration of functions of components of the present invention and thus can be changed according to the custom or intention of users or operators. Therefore, definition of such terms should be determined according to overall disclosures set forth herein. 
       FIG. 1  is a cross-sectional view of a washing machine according to one embodiment of the present invention, and  FIG. 2  is a block diagram of the washing machine according to the embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , the washing machine includes a cabinet  100  constituting the appearance of the washing machine, a tub  105  disposed inside the cabinet  100  to contain wash water, and a drum  110  rotatably disposed inside the tub  105 . 
     The cabinet  100  has a door  115  mounted to the front side thereof to open or close an opening of the cabinet  100  through which laundry is put into the drum, and the tub  105  is provided on upper and lower sides thereof with a support spring  120  and a damper  125  to hold the tub  105  in a buffering manner. The upper side of the tub  105  is provided with a detergent supply part  130  for supplying detergent into the tub and a water supply tube  140  which has a water supply valve  135  and supplies wash water into the tub  105 . 
     A gasket  142  is provided with an assistant water supply tube  143 . The assistant water supply tube  143  passes through the gasket  142  interposed between the cabinet  100  and the tub  105  to supply wash water for steam to a preset steam level, and is connected to the water supply valve  135  to supply the wash water for steam into a heater compartment  160  so as to prevent the wash water for steam from being absorbed by the laundry. 
     The tub  105  is provided at the rear side with a drive motor  145  adapted to drive the drum  110 , and on the bottom with a drain path  150  and a drain pump  155  through which wash water is discharged to the outside. The heater compartment  160  is defined at a lower part of the tub  105  to contain the wash water and is provided with a wash heater  165  therein to heat the wash water when generating steam. A plurality of lifts  170  are provided on the inner surface of the drum  110 . 
     The washing machine includes a controller  200  to control a steam washing process. For control of the washing machine, the controller  200  is electrically connected to the water supply valve  135  for supplying wash water into the tub  105 , to the drive motor  145  for alternately rotating the drum in the forward and reverse directions to agitate laundry received in the drum, to the drain pump  155  for discharging the wash water to the outside of the cabinet  100 , and to the wash heater  165  for heating wash water for steam. 
     Further, the washing machine includes a key input unit  210  for sending a key input signal to the controller  200  and a level detection sensor  220  for detecting a level of wash water inside the tub  105  when the wash water is supplied into the tub  105 . 
     Hereinafter, a steam washing method of the washing machine according to one embodiment of the present invention will be described with reference to  FIG. 3 . 
     First, in S 100 , when a steam washing course is selected on the key input unit  210  with laundry put into the drum  110  of the washing machine, the controller  200  outputs a control signal to open the water supply valve  135 . Then, wash water for steam is supplied into the tub  105  until it reaches a preset steam level for performing the steam washing course, in S 103 . 
     When the level detection sensor  220  detects that wash water for steam reaches the preset steam level inside the heater compartment  160  at the lower part of the tub  105  in S 106 , the controller  200  closes the water supply valve  135  and operates the drive motor  145  to drive the drum  110 , thereby agitating the laundry in the drum  110 . Here, the drum  110  may be alternately rotated in the forward and reverse directions to enhance efficiency of the steam washing course. 
     Then, the wash heater  165  is operated to heat the wash water to a preset temperature and generate steam in S 109 ˜S 112 , and primary steam washing is performed in S 115 . In the steam washing course, wash water is intermittently supplied through the water supply valve  135  to efficiently generate steam while the wash heater  165  heats the wash water to generate steam. Hot steam generated by means of the wash heater  165  is used to sterilize bacteria and fungi in laundry. Further, since a window of the door  115  is fogged by steam generated during the steam washing course, it is possible to visually confirm the steam washing course. 
     After completion of the primary steam washing in S 115 , the controller  200  opens the water supply valve  135  and starts wash water supply into the tub  105  along with detergent contained in the detergent supply unit  130  in S 121 . When the level detection sensor  220  detects that wash water reaches a preset water level, the controller  200  closes the water supply valve  135  to stop the wash water supply in S 124 . 
     Next, in S 127  and S 130 , a washing cycle is performed by heating the wash water to a preset temperature with the wash heater  165  while agitating the laundry in the drum  110  by operating the drive motor  145  to alternately rotate the drum  110  in the forward and reverse directions. After completion of the washing cycle, the controller  200  stops the wash heater  165  and the drive motor  145  in S 133 . 
     Then, a rinsing cycle is performed to remove detergent remnants in S 136 . The rinsing cycle is performed once or more by supplying wash water into the tub  105  through the water supply valve  135 . Here, the drive motor  145  is operated to alternately rotate the drum  110  in the forward and reverse directions in response to a control signal from the controller  200 , thereby agitating the laundry in the drum  110 . 
     After completion of the rinsing cycle, a spin-dry cycle is performed by operating the drive motor  145  to rotate the drum  110  in S 139 , followed by secondary steam washing. 
     For the secondary steam washing, the water supply valve  135  is opened and steam water supply is started to supply wash water for steam into the tub  105  up to a preset steam level in S 142 . At this time, the wash water for steam is supplied through the assistant water supply tube  143  so as to prevent the wash water removed from the laundry by a spin-dry cycle from being absorbed by the laundry. When the level detection sensor  220  detects that the wash water reaches the preset steam level in S 145 , the controller  200  closes the water supply valve  135  and operates the drive motor  145  to rotate the drum  110 , thereby agitating the laundry received in the drum  110 . Here, the drum  110  may be alternately rotated in the forward and reverse directions. 
     Then, in the steam washing method of the embodiment, the wash heater  165  is operated to heat the wash water to a preset temperature and generate steam in S 148 ˜S 151 , and the secondary steam washing is performed in S 154 . During the secondary steam washing, wash water is intermittently supplied through the water supply valve  135  or the assistant water supply valve  143  to maintain the steam level and efficiently generate steam while the wash heater  165  heats the wash water to generate the steam. After completion of the secondary steam washing of S 157 , the washing process is completed. 
     In the steam washing method of the washing machine according to the embodiment, steam washing is performed again after completion of the spin-dry cycle, thereby improving sterilization effect of the steam washing course by sterilizing bacteria attached to the laundry during the washing and rinsing cycles. Further, in the steam washing method of this embodiment, steam is generated by means of the wash heater without using a separate steam heater, so that steam is not generated during the washing cycle, thereby reducing power consumption. 
     Next, a steam washing method of the washing machine according to anther embodiment of the present invention will be described with reference to  FIG. 4 . For convenience of description, illustration and description of the same or similar components as those of the above embodiment will be omitted herein. 
       FIG. 4  is a flowchart of a steam washing method of a washing machine according to another embodiment of the present invention. 
     Referring to  FIGS. 1 ,  2  and  4 , when a steam washing course is selected on the key input unit  210  with laundry received in the drum  110  of the washing machine in S 200 , the controller  200  outputs a control signal to open the water supply valve  135 . Then, wash water for steam is supplied into the tub  105  until it reaches a preset steam level for performing the steam washing course, in S 203 . 
     When the level detection sensor  220  detects that the wash water reaches the preset steam level inside the heater compartment  160  defined at the lower part of the tub  105  in S 206 , the controller  200  closes the water supply valve  135  and operates the drive motor  145  to drive the drum  110 , thereby agitating the laundry in the drum  110 . Here, the drum  110  may be alternately rotated in the forward and reverse directions to enhance efficiency of washing operation. 
     Then, the wash heater  165  is operated to heat the wash water to a preset temperature and generate steam in S 209 ˜S 212 , and primary steam washing is performed in S 215 . In the steam washing course, wash water is intermittently supplied through the water supply valve  135  to efficiently generate steam while the wash heater  165  heats the wash water to generate the steam. 
     After completion of the primary steam washing in S 215 , the controller  200  opens the water supply valve  135  and starts wash water supply into the tub  105  along with detergent contained in the detergent supply part  130  in S 221 . When the level detection sensor  220  detects that wash water reaches a preset wash water level, the controller  200  closes the water supply valve  135  to stop the wash water supply in S 224 . 
     Next, in S 227  and S 230 , a washing cycle is performed by heating the wash water to a preset temperature with the wash heater  165  while agitating the laundry in the drum  110  by operating the drive motor  145  to alternately rotate the drum  110  in the forward and reverse directions. After completion of the washing cycle, the controller  200  stops the wash heater  165  and the drive motor  145  in S 233 . 
     Then, a rinsing cycle is performed in S 236 . The rinsing cycle is performed by supplying wash water into the tub  105  through the water supply valve  135  and then alternately rotating the drum  110  in the forward and reverse directions to agitate the laundry in the drum  110  by the drive motor  145  in response to a control signal from the controller  200 . The rinsing cycle is performed once or more, and the last rinsing cycle will be referred to as a final rinsing cycle. 
     Here, secondary steam washing is performed before the final rinsing cycle, that is, between the rinsing cycles. After completion of the secondary steam washing, the final rinsing cycle is performed, thereby completing the rinsing cycle. 
     For the secondary steam washing, the water supply valve  135  is opened and steam water supply is started to supply wash water for steam into the tub  105  up to a preset steam level in S 239 . When the level detection sensor  220  detects that the wash water reaches the preset steam level in S 242 , the controller  200  closes the water supply valve  135  and operates the drive motor  145  to rotate the drum  110 , thereby agitating the laundry in the drum  110 . Here, the drum  110  may be alternately rotated in the forward and reverse directions. 
     Then, in the steam washing method of this embodiment, the wash heater  165  is operated to heat wash water to a preset temperature and generate steam in S 245 ˜S 248 , and the secondary steam washing is performed in S 251 . During the secondary steam washing, wash water is intermittently supplied through the water supply valve  135  or the assistant water supply valve  135  to maintain the steam level and efficiently generate steam while the wash heater  165  heats the wash water to generate the steam. After completion of the secondary steam washing of S 254 , the final rinsing cycle is performed in S 257 . Since the final rinsing cycle is performed after steam washing, it is possible to prevent effects of fabric softeners and the like used in the rinsing cycle from being reduced due to the steam washing. After completion of all rinsing cycles, a spin-dry cycle is performed in S 260 , thereby completing the washing process. 
     In the steam washing method of this embodiment, steam washing is performed again between the washing cycle and the final rinsing cycle, improving sterilization effect of the steam washing operation by sterilizing bacteria attached to laundry during the washing and rinsing cycles. Further, in the steam washing method of this embodiment, steam is generated by means of a wash heater without using a separate steam heater so that steam is not generated during the washing cycle, thereby reducing power consumption. 
     The washing machine and steam washing method thereof according to the present invention have various advantageous effects. 
     For example, hot steam is generated using a wash heater to perform steam sterilization of bacteria and fungi in laundry. 
     Additionally, since steam washing is performed again after a spin-dry cycle, bacteria and fungi attached to laundry during washing and rinsing cycles can be sterilized, thereby improving sterilization effects. 
     Further, since steam washing is performed again after the washing and rinsing cycles, bacteria and fungi attached to laundry during the washing and rinsing cycles can be sterilized, thereby improving the sterilization effects. 
     Further, since a glass window of a door is fogged by steam generated during the steam washing, it is possible to visually confirm the steam washing process. 
     Moreover, since steam is generated by the wash heater without using a separate steam heater, the washing machine can perform a washing cycle without generating steam, thereby reducing power consumption. 
     Although the present invention has been described with reference to the embodiments and the accompanying drawings, the embodiments and drawings are given by way of illustration only, and, it will be apparent to those skilled in the art that various modifications and equivalent embodiments can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should be limited only by the accompanying claims.