Abstract:
A method of cleaning a washing tub mounted in a water tub of a washing machine includes supplying water necessary to clean the washing tub to the water tub, and rotating the washing tub while supplying heat to the water tub by means of at least one heat supply device mounted in the washing machine. The washing tub is maintained at high temperature when the washing tub is cleaned, whereby decontamination and disinfection efficiency is improved. Also, water required to clean the washing tube is separately supplied to increase the rotating speed of a washing motor, whereby cleaning efficiency is improved.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of Korean Patent Application No. 2005-3392, filed on Jan. 13, 2005 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a washing machine and a washing tub cleaning method, and, more particularly, to a washing machine and a washing tub cleaning method that is capable of supplying high-temperature heat to a washing tub when the washing tub is cleaned, thereby improving cleaning efficiency.  
         [0004]     2. Description of the Related Art  
         [0005]     Generally, a washing machine comprises a water tub, a washing tub rotatably mounted in the water tub, a water supply valve to control the flow of water supplied to the water tub, a washing motor to drive the washing tub and a pulsator. When a user places laundry into the washing tub, and then inputs a washing command, the washing machine successively performs a washing operation, a rinsing operation, and a dewatering operation.  
         [0006]     After the washing machine is used for a long period of time, various impurities are attached to the washing tub or bacteria propagate within the washing tub. In order to solve these problems, various washing tub disinfecting methods have been proposed, one example of which is disclosed in Korean Unexamined Patent Publication No. 2001-0010111.  
         [0007]     The conventional washing tub disinfecting method is performed as follows: a detergent and a disinfectant are placed in the washing tub, the pulsator is operated for a predetermined period of time to dissolve the detergent and the disinfectant, water is further supplied, and the pulsator is operated again to disinfect the washing tub with wash water containing detergent and disinfectant dissolved therein. In this way, the washing tub disinfecting method is performed.  
         [0008]     When the washing tub is disinfected according to the above-mentioned method, however, the temperature of the wash water is lower than the temperature appropriate for impurity removal and disinfection (approximately 60° C.), and therefore, the washing tub is not properly cleaned and disinfected. Especially when cold water is supplied to the washing tub, decontamination and disinfection efficiency achieved by the detergent and the disinfectant are considerably lowered.  
         [0009]     Furthermore, a large amount of water is supplied to the washing tub at once to clean the washing tub. Consequently, the washing motor must be operated at a relatively low rotating speed to protect the washing motor, and therefore, the current of water is slow. As a result, the magnitude of a mechanical force affecting the decontamination is small, and therefore, the washing tub is not properly cleaned.  
       SUMMARY OF THE INVENTION  
       [0010]     Illustrative, non-limiting embodiments overcome the above disadvantages, as well as other disadvantages not described above.  
         [0011]     A method and apparatus consistent with the present invention is capable of maintaining a washing tub at high temperature when the washing tub is cleaned, thereby improving decontamination and disinfection efficiency.  
         [0012]     The present invention also provides a washing machine and a washing tub cleaning method that is capable of separately supplying water required to clean the washing tube to increase the rotating speed of a washing motor, thereby improving cleaning efficiency.  
         [0013]     In accordance with one aspect of the invention, a method of cleaning a washing tub mounted in a water tub of a washing machine, comprises: supplying water necessary to clean the washing tub to the water tub; and rotating the washing tub while supplying heat to the water tub by means of at least one heat supply device mounted in the washing machine.  
         [0014]     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which:  
         [0016]      FIG. 1  is a sectional view showing a drum washing machine according to an embodiment of the present invention;  
         [0017]      FIG. 2  is a block diagram of the drum washing machine shown in  FIG. 1 ;  
         [0018]      FIG. 3  is a flow chart illustrating a washing tub cleaning process in the drum washing machine shown in  FIGS. 1 and 2 ; and  
         [0019]      FIG. 4  is a timing chart illustrating the washing tub cleaning process in the drum washing machine shown in  FIGS. 1 and 2 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Reference will now be made in detail to the embodiment of the present invention. The embodiment is described below to explain the present invention by referring to the figures.  
         [0021]     As shown in  FIG. 1 , the drum washing machine comprises a drum-type water tub  11  mounted in a machine body  10  to receive water, and a drum-type washing tub  12  rotatably mounted in the water tub  11 .  
         [0022]     The water tub  11  mounted in the machine body  11  is disposed at a predetermined angle (a) to the installation surface of the washing machine so that the front part of the water tub  11 , at which an inlet  11   a  is formed, is higher than the rear part of the water tub  11 . Similarly, the washing tub  12  mounted in the water tub  11  is disposed at the same angle as the water tub  11  so that the front part of the washing tub  12 , at which an inlet  12   a  is formed, is higher than the rear part of the washing tub  12 . That is, the washing tub  12  is disposed so that the rotating center line A of the washing tub  12  is at the predetermined angle (α) to the installation surface of the washing machine while the front part of the washing tub  12  having the inlet  12   a  formed thereat faces the front upper part of the washing machine. To the center of the rear part of the washing tub  12  is attached a rotary shaft  15   a , which is rotatably supported at the center of the rear part of the water tub  11  so that the washing tub  12  is rotated in the water tub  11 . At the circumferential part of the washing tub  12  are formed a plurality of through-holes  12   b , and to the inner circumferential surface of the washing tub  12  are attached a plurality of lifters  14 , by which the laundry is lifted and dropped when the washing tub  12  is rotated.  
         [0023]     At the rear of the water tub  11  is mounted a washing motor  15  to rotate the rotary shaft  15   a  connected to the washing tub  12 . At the front part of the machine body  10  is formed an inlet  16 , through which the laundry is put into the washing tub  12  or removed from the washing tub  12 , corresponding to the inlet  12   a  of the washing tub  12  and the inlet  11   a  of the water tub  11 . The inlet  16  is closed by a door  17  hingedly attached to the front part of the machine body  10 . Between the water tub  11  and the inlet  16  of the machine body is mounted a diaphragm  13 .  
         [0024]     Above the water tub  11  are mounted a detergent supply device  18  to supply a detergent to the water tub  11 , a steam device  30  to supply steam to the water tub  11 , a water supply device  20  to supply water to the water tub  11  and the steam device  30 . Under the water tub  11  are mounted a drainage device  19 , comprising a drain pipe  19   a , a drain valve  19   b  and a drain motor  19   c , to drain water from the water tub  11 , and a lower heater  40  to heat water in the water tub  11 .  
         [0025]     The detergent supply device  18  has a detergent receiving space defined therein. The detergent supply device  18  is disposed at the front part of the machine body  10  so that a user can easily put detergent into the detergent supply device  18 . The steam device  30  comprises a steam generator  31  to generate steam and a steam supply device  32  to supply the generated steam to the water tub. The steam supply device  32  comprises a steam supply pipe  34  connected between the steam generator  31  and the water tub  11 , and a steam supply valve  33  mounted on the steam supply pipe  34 . In the steam generator  31  is mounted a heater (not shown) to heat water supplied into the steam generator  31 .  
         [0026]     The water supply device  20  comprises a first water supply pipe  21  to supply water to the water tub  11 , and a first water supply valve  22  mounted on the first water supply pipe  21  to control water supply through the first water supply pipe  21 . The first water supply pipe  21  is connected to the detergent supply device  18  so that water supplied from outside the washing machine is supplied to the detergent supply device  18 . Between the detergent supply device  18  and the water tub  11  is mounted a connection pipe  23  to supply water passing through the detergent supply device  18  to the water tub  11 . In this way, water passes through the detergent supply device  18  and is then supplied to the water tub  11 . As a result, the detergent in the detergent supply device  18  is supplied to the water tub while being dissolved in the water. The water supply device  20  further comprises a second water supply pipe  24  to supply water to the steam generator  31 , and a second water supply valve  25  mounted on the second water supply pipe  24  to control supply of water to the steam generator  31 .  
         [0027]     As shown in  FIG. 2 , the drum washing machine further comprises: a water level detection unit  52  to detect a level of water supplied to the water tub; a washing motor drive unit  53  to drive the washing motor  15 ; a lower heater drive unit  54  to drive the lower heater  40 ; a water supply valve drive unit  55  to drive the first and second water supply valves  22  and  25 ; a steam supply valve drive unit  56  to drive the steam supply valve  33 ; a drain valve drive unit  57  to drive the drain valve  19   b ; and a microcomputer  51  to control the respective devices of the drum washing machine.  
         [0028]     Now, a method of cleaning the washing tub of the drum washing machine shown in  FIGS. 1 and 2  will be described with reference to  FIGS. 3 and 4 .  
         [0029]     When a user selects a washing tub cleaning process, the first water supply valve  22  is opened to initially supply a portion of washing tub cleaning water, the amount of which is predetermined, to the water tub  11  through the detergent supply device  18  (step  60 ). When the water is initially supplied, it is preferable to control the amount of water to be supplied using a value detected by the water level detection unit  52  so that the water arrives at the lowest surface of the diaphragm  12  mounted at the inlet of the drum washing machine. A detergent or a disinfectant is put in the detergent supply device  18  so that water containing the detergent or the disinfectant dissolved therein is supplied to the water tub  11 .  
         [0030]     After the initial water supply is completed, the washing motor  15  is driven for a predetermined period of time (for example, repetitively turned on for  10  seconds and then off for 5 seconds—see  FIG. 4 ) to rotate the washing tub  12 , and the steam generator  31  generates steam, which is supplied to the water tub  11  and the washing tub  12  through the steam supply pipe  34  (step  62 ). As the steam is supplied to the water tub  11  and the washing tub  12 , the interior temperature of the water tub  11  is increased, since the temperature of the steam is high, for example, above approximately 70° C., and therefore, the cleaning or disinfecting activity of the detergent or the disinfectant is activated. When the washing tub  12  is cleaned with only the initially supplied water, the washing motor  15  can be operated at a relatively high rotating speed. Consequently, strong current of flow is generated by the washing motor  15 , and therefore, a cleaning force is increased.  
         [0031]     In the illustrated embodiment, the steam is supplied while the washing tub  12  is rotated after the water is initially supplied, although various other devices may be used to increase the interior temperature of the water tub  11 . For example, a drying device disclosed in Korean Unexamined Patent Publication No. 10-2004-0022828 may be used to supply hot air to the water tub and the washing tub to increase the interior temperature of the water tub.  
         [0032]     After the initial water supply and the first cleaning are completed, the first water supply valve  22  is reopened to further supply washing tub cleaning water to the water tub  11  (step  64 ). While the water is heated by the lower heater  40 , the washing motor  15  is driven (repetitively turned on for 10 seconds and then off for 5 seconds—see  FIG. 4 ) to rotate the washing tub  12  (step  66 ). During the second cleaning, the washing tub is rotated while a great quantity of water is heated to clean the washing tub  12  and wash out various contaminants separated from the washing tub  12  during the first cleaning.  
         [0033]     After the supplementary water supply and the second cleaning are completed, rinsing and dewatering operations are performed (step  68 ). In this way, the washing tub cleaning process is completed.  
         [0034]     As apparent from the above description, the interior temperature of the water tub is highly increased as steam or hot air is supplied to the water tub when the washing tub is cleaned, and therefore, the cleaning or disinfecting activity of the detergent or the disinfectant is activated. Consequently, the present invention has the effect of cleaning and disinfection efficiency.  
         [0035]     Also, the washing tub is cleaned only with a portion of the washing tub cleaning water during the first cleaning, and therefore, the rotating speed of the washing motor can be increased, which increases a mechanical force affecting the decontamination. Consequently, the present invention has the effect of increasing a cleaning force.  
         [0036]     As the cleaning force is increased as described above, the washing tub is cleaned within a relatively short period of time. Consequently, the present invention has the effect of reducing the time necessary to clean the washing tub.  
         [0037]     Although an embodiment of the present invention has been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.