Abstract:
Disclosed is an apparatus and method for machine washing that includes a sterilizer capable of continuously exhibiting antibiotic and sterilization functions during washing and rinsing processes and reducing the consumption amount of Ag. The washing machine comprises a water reservoir to contain washing water, a sterilizer sterilizing the washing water through an electrolysis process, and a circulator circulating the washing water in the sterilizer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 2007-0034424, filed on Apr. 6, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The present invention relates to a washing machine and a method of washing. More particularly, the present invention relates to a washing machine comprising a sterilizer that sterilizes washing water and a circulator that circulates the washing water in the sterilizer. 
     2. Description of the Related Art 
     In general, a washing machine washes the laundry in a washing tub by stirring the laundry together with washing water mixed with detergent. 
     Such a washing machine comprises a body forming an external appearance, a water reservoir installed in the body and containing washing water, a detergent supply apparatus that mixes detergent with water supplied from an exterior and supplies the water to the water reservoir. 
     Recently, an Ag solution supply apparatus, which supplies Ag solution by dissolving Ag ions exhibiting antibiotic and sterilization functions in washing water, has been added to the washing machine in order to wash the laundry and sterilize bacteria existing in the washing water and the laundry. 
     The Ag solution supply apparatus comprises one pair of Ag electrodes to which voltage is applied, and supplies Ag ions, which are generated by an Ag plate during electrolysis when the washing water passes through the Ag electrodes, to a water reservoir. 
     The Ag solution supply apparatus provided in the washing machine is installed on a water supply path, which supplies the washing water to the water reservoir, together with a detergent dissolver, and supplies the Ag ions to the washing water supplied to the water reservoir. However, the Ag solution supply apparatus cannot supply the Ag ions any more after the water supply is terminated, so antibiotic and sterilization functions cannot be continuously exhibited during washing and rinsing processes. 
     Further, the density of the Ag ions, which are generated by the Ag solution supply apparatus and provided to the washing water, is gradually reduced through reaction with other ions existing in the washing water, so the sterilization effect may be reduced. If many Ag ions are supplied to the washing water in consideration of the fact, consumption amount of Ag in the Ag plate may be increased, resulting in reduction of the life span of the Ag plate. 
     SUMMARY 
     Accordingly, one or more embodiments of the present invention provide a washing machine capable of continuously exhibiting antibiotic and sterilization functions during washing and rinsing processes. 
     One or more embodiments of the present invention also provide a washing machine capable of reducing consumption amount of Ag in an Ag plate. 
     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
     The foregoing and/or other aspects of embodiments of the present invention are achieved by providing a washing machine including a water reservoir to contain washing water, a sterilizer sterilizing the washing water through an electrolysis process, and a circulator circulating the washing water in the sterilizer. 
     The sterilizer comprises a first electrode including Ag and a second electrode including a metal having an ionization tendency lower than the ionization tendency of Ag. 
     The second electrode may comprise Ti. 
     The second electrode may also comprise Pt or Ir coated on a surface thereof. 
     The washing machine further comprises a power supply that supplies electric current to the first and second electrodes, and a controller that switches polarity of the electric current applied to the first and second electrodes. 
     The controller operates in a first mode, in which the first electrode becomes an anode and the second electrode becomes a cathode, or a second mode in which the second electrode becomes an anode and the first electrode becomes a cathode. 
     The circulator comprises a circulation pipe, which forms a circulation path such that the washing water is circulated in the water reservoir, and a circulation pump that pumps the washing water in the circulation path. 
     The circulation pipe may be provided along a circumference of the water reservoir. 
     The water reservoir comprises an inlet to introduce the washing water to the circulation path, and an outlet to discharge the washing water having passed the circulation path to the water reservoir. 
     The outlet may be provided at an upper portion of the water reservoir. 
     The outlet may be provided with an injection nozzle that injects the washing water such that the washing water is uniformly spread in the water reservoir. 
     The washing machine may further comprise a salt supply unit that supplies salt to the washing water. 
     The salt supply unit may be provided in a detergent supply apparatus that supplies detergent to the water reservoir. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a schematic view illustrating an internal structure of a washing machine including a sterilizer used in embodiments of the present invention; 
         FIG. 2  is an exploded perspective view showing the construction of the sterilizer in  FIG. 1 ; and 
         FIG. 3  is a schematic view showing an internal structure of the washing machine in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. 
       FIG. 1  is a schematic view showing an internal structure of a washing machine according to an embodiment of the present invention. 
     The washing machine comprises a body  1  forming an external appearance, a water reservoir  2  installed in the body  1 , and a drum  3  rotatably installed in the water reservoir  2 . 
     A door  4  is installed in the front of the body  1  to open and close the opened front of the body  1 . Water supply valves  5 , which are connected to an external water supply source, and a detergent supply apparatus  6  are installed at the upper portion of the water reservoir  2 , in which the detergent supply apparatus  6  dissolves detergent in water supplied through the water supply valves  5  and supplies the water to the water reservoir  2 . 
     The detergent supply apparatus  6  comprises a housing  6   a  and a detergent box  6   b  detachably provided in the housing  6   a.    
     A circulation pipe  7  that forms a circulation path is installed at the outer side of the water reservoir  2  such that the washing water can be circulated in the water reservoir  2 . A circulation pump  8  is installed on the circulation path formed by the circulation pipe  7 . 
     A three-way valve  9  is installed at the lower portion of the water reservoir  2  in order to switch a path between a drain pipe  12 , which drains the washing water from the water reservoir  2 , and the circulation pipe  7 . 
     The circulation pipe  7  interconnects the upper and lower portions of the water reservoir  2  such that the washing water in the lower portion of the water reservoir  2  can be moved to the upper portion of the water reservoir  2 . At this time, the circulation pump  8  pumps the washing water, which is supplied to the circulation pump  8  from the lower portion of the water reservoir  2  along the circulation pipe  7 , such that the washing water can be discharged from the upper portion of the water reservoir  2 . 
     A sterilizer  100  is installed above the circulation pump  8  to exhibit sterilization function by generating Ag ions through an electrolysis operation or activating the generated Ag ions. 
       FIG. 2  is an exploded perspective view showing the construction of the sterilizer in  FIG. 1 . 
     The sterilizer  100  comprises a storage container  110  having an inlet  110   a , which has an opened upper surface and introduces washing water inside the sterilizer  100 , and an outlet  110   b  that discharges the washing water. 
     A circulation pipe is connected between the inlet  110   a  and the outlet  110   b , a cover  120  is installed at the opened upper surface of the storage container  110 , and first and second electrodes  130  and  140  are installed at the cover  120  in order to form electrodes for electrolysis. 
     The first and second electrodes  130  and  140  are installed in the path in the storage container  110  through slots  120   a  and  120   b  formed in the cover  120 , and are immersed when the washing water passes through the storage container  110 . 
     Further, the first and second electrodes  130  and  140  have a plate shape as shown in  FIG. 2 , face each other, and are arranged in parallel with the flowing direction of the washing water in the storage container  110 . 
     As the first and second electrodes  130  and  140  have a plate shape, the contact area with the washing water can be increased. However, in other embodiments, the electrodes may also have a bar shape. 
     The first and second electrodes  130  and  140  may comprise Ag and Ti, respectively. In addition to Ti, the second electrode  140  may also comprise other metals featuring an ionization tendency lower than that of Ag. 
     When the second electrode  140  comprises Ti, metals (e.g. Pt and Ir) having an ionization tendency lower than that of Ag may be coated on the surface of the second electrode  140  through plating in order to improve the corrosion-resistance. 
       FIG. 3  is a schematic view showing an internal structure of the washing machine in  FIG. 1 . 
     The water reservoir  2  is installed in the body  1  of the washing machine, and the drum  3  is installed in the water reservoir  2 . 
     The water supply valves  5  that supply water to the water reservoir  2  are connected to the detergent supply apparatus  6  through a water supply pipe  11  at the upper portion of the water reservoir  2 , and an outlet  3   b  and an inlet  3   a  are formed at the upper and lower portions of the water reservoir  2 , respectively. 
     The circulation pipe  7  that forms a circulation path  20  by interconnecting the outlet  3   b  and the inlet  3   a  is connected to the outer side of the water reservoir  2 , and the circulation pump  8  and the sterilizer  100  are connected to the circulation path  20 . 
     The inlet  3   a  is used as a waterway to drain the washing water in the water reservoir  2 , and the three-way valve  9  is installed at the lower portion of the inlet  3   a  to switch the path such that the washing water introduced through the inlet  3   a  can be sent to the drain pipe  12  or the circulation pipe  7 . 
     An injection nozzle  21  is installed at the outlet  3   b  such that the drained washing water can be spread over the wide range. The outlet  3   b  and the injection nozzle  21  are installed at the upper portion of the water reservoir  2 , so that the washing water passing through the sterilizer  100  can be uniformly spread in the drum  3  and the water reservoir  2  when the washing water is discharged into the water reservoir  2 . 
     As the washing or rinsing process starts, washing water is filled in the water reservoir  2  up to a predetermined water level, and the sterilizer  100  is positioned higher than the water level of the washing water. Accordingly, the electrodes  130  and  140  in the sterilizer  100  are not immersed in the washing water in a state when the circulation pump  8  is not operating, so that the sterilizer  100  can be prevented from being contaminated due to water remaining after the washing or rinsing process. In addition, even if the locking state of the door is released due to the abnormal operation of the washing machine, or other problems occur, electric shock can be prevented. 
     The two electrodes  130  and  140  of the sterilizer  100  are connected to a power supply  30  such that power can be supplied to the electrodes  130  and  140 . The power supply  30  converts electric current such that DC power can be supplied to the electrodes  130  and  140 . 
     The polarity of the DC power supplied to the electrodes  130  and  140  can be changed by a controller  40  that controls the power supply  30 . 
     The sterilizer  100  operates in two modes. In the first mode, the first electrode  130  serves as an anode because positive (+) polarity of the DC power is connected to the first electrode  130  by the controller  40  and the second electrode  140  serves as a cathode because negative (−) polarity of the DC power is connected to the second electrode  140 . In the second mode, the polarity of the electrode is inversed as compared to the first mode, so the first electrode  130  serves as the cathode and the second electrode  140  serves as the anode. 
     In detail, in the first mode, the first electrode  130  comprising Ag serves as the anode to emit Ag ions into the washing water. That is, the first electrode  130  and the second electrode  140  become the anode and the cathode, respectively, so electric current flows in the two electrodes. In addition, Ag is electrolyzed in the first electrode  130 , so Ag ions in Ag +  state are generated and supplied to the circulated washing water. 
     In the second mode, the polarities of the first and second electrodes  130  and  140  are inversed as compared with the first mode, so the second electrode  140  comprising Ti becomes the anode, and the first electrode  130  (Ag electrode) becomes the cathode. 
     In such a case, the Ag ions are not emitted through the first electrode  130  and electrolysis of the electrode is not performed in the second electrode  140 . Accordingly, ions (e.g. Ti + ) are not generated in the second electrode  140 , and electric current flows between the first electrode  130  and the second electrode  140  due to an electrolyte contained in the washing water or ions generated by the detergent. 
     In such a second mode, ions for sterilization are not directly generated, but ions contained in the washing water are activated. That is, compound in the neutral state contained in the washing water can be ionized through the electrolysis operation. 
     In particular, when Ag ions are emitted into the washing water in the first mode, if the Ag ions are reduced in the sterilization process and become electrically neutral, the sterilization effect is discontinued. Thus, the Ag ions in the neutral state are restored into Ag ions through the electrolysis operation. 
     In the second mode, the bacteria contained in the washing water are sterilized by the electric current flowing between the first electrode  130  and the second electrode  140 . That is, the cell membrane of the bacteria contained in the washing water is partially destroyed by the electric current or pores may be formed in the cell membrane while the washing water is passing between the first electrode  130  and the second electrode  140 . 
     The cell membrane of the bacteria subject to the electric current is destroyed and disappears. Even if the bacteria do not disappear, the Ag ions can easily penetrate into the bacteria. If the Ag ions have been emitted into the washing water in the first mode, the bacteria disappear due to penetration of the Ag ions. 
     The effect on the bacteria due to the electric current flowing between the first electrode  130  and the second electrode  140  is increased in proportion to the density of the electric current flowing between the two electrodes  130  and  140 , that is, the electric current per unit area. 
     The sterilization function in the first and second modes as described above can be variously applied throughout the entire washing process, and embodiments regarding the sterilization function will be described. 
     In one embodiment, the sterilizer  100  operates in the first mode in order to emit Ag ions, and the first mode is switched to the second mode after a predetermined time period passes. 
     This can be commonly applied to the washing and rinsing processes. In  FIG. 3 , in a state where the washing water is supplied to the water reservoir  2  through the water supply valves  5  and the detergent supply apparatus  6 , as the three-way valve  9  connects the inlet  3   a  to the circulation path  20  to form the circulation path  20 , and the circulation pump  8  operates, the washing water is circulated through the circulation path  20  and the sterilizer  100  connected to the circulation path  20 . 
     As the sterilizer  100  operates in the first mode, the Ag ions are emitted into the washing water through the first electrode  130 , and the washing water containing the Ag ions are injected into the water reservoir  2  and the drum  3  through the injection nozzle  21 , thereby exhibiting the antibiotic and sterilization functions. 
     After a predetermined time period passes, the sterilizer  100  operates in the second mode. That is, the cell membrane of the bacteria is subject to the electric current flowing between the two electrodes  130  and  140 , so the bacteria is destroyed or disappears due to the Ag ions. Further, Ag, which has been emitted in the first mode and reduced through the sterilization process of the bacteria or other methods, is activated into Ag ions in the second mode. 
     The consumed Ag ions are restored through the procedure as described above, so that the operation time of the first mode can be shortened, and thus the consumption amount of Ag can be reduced in the first electrode. 
     In another embodiment, the sterilizer  100  operates in sequence of the second mode and the first mode. The reason of primarily operating the sterilizer  100  in the second mode is that the Ag ions emitted during the washing process may be affected by the high-density detergent dissolved in the washing water and other ions, and the sterilization function of the Ag ions may be interrupted. Thus, the sterilizer  100  operates in the second mode during the washing process such that the sterilization function due to the electric current between the first electrode  130  and the second electrode  140  can be exhibited, and then the sterilizer  100  operates in the first mode during the rinsing process, in which the density of the detergent is reduced, such that the Ag ions can be supplied to the washing water. 
     In further another embodiment, the washing machine can operate in a washing mode, in which the water reservoir and the drum are washed, separately from the washing and rinsing processes. 
     The washing mode corresponds to a dedicated washing process of removing biofilms formed in the water reservoir and the drum due to the propagation of bacteria. That is, in a state where washing water is supplied to the water reservoir without the laundry, the circulation pump  8  operates to circulate the washing water and the sterilizer  100  operates in the second mode or the first mode. 
     In order to improve the washing effect by the circulated washing water, a salt supply unit (not shown) can be provided to supply salt to the supplied water. The salt supply unit can be additionally provided to the washing machine, or can also be provided to the detergent box  6   b  of the detergent supply apparatus  6  (see  FIG. 1 ). 
     As the salt is dissolved in the washing water, HOCl is generated through an electrolysis process. Since reaction and generation conditions for generation of the HOCl are well known to the skilled in the art, details thereof will be omitted here. 
     In order to improve the washing effect by the circulated washing water, a salt supply unit  6   c  can be provided to supply salt to the supplied water. The salt supply unit  6   c  can be additionally provided to the washing machine, or can also be provided to the detergent box  6   b  of the detergent supply apparatus  6  (see  FIG. 1 ). 
     According to the washing machine of the present invention as described above, the sterilization effect can be maximized by using a small quantity of Ag and can be continued throughout the entire washing process, so that not only harmful microorganisms contained in the laundry but also microorganisms remaining or growing in the washing machine can be sterilized using the circulator, and thus the laundry can be prevented from being secondarily contaminated. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.