Abstract:
A dishwasher and a method of controlling a dishwasher are provided. Using this method of controlling a dishwasher, it is possible to quickly and precisely determine, during the washing of dishes, whether nozzles are clogged with impurities. It is also possible to easily address the problems associated with clogged nozzles by terminating the operation of a washing pump for a predefined amount of time, and then resuming the operation of the washing pump to clear obstructions from the nozzles.

Description:
This application claims priority to Korean Patent Application No. 10-2007-0096733 filed in Korea on Sep. 21, 2007, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     A dishwasher and a method of controlling a dishwasher are provided, and more particularly, a dishwasher and a method of controlling a dishwasher in which it can be precisely determined whether nozzles are clogged and in which clogged nozzles can be easily cleaned. 
     2. Background 
     Dishwashers are devices for washing dishes soiled with food residues by spraying wash fluid onto the dishes. Dishwashers include a washing tub having racks for holding dishes, a fluid supply device supplying clean wash fluid to a sump disposed below the washing tub, a wash fluid spray device spraying the wash fluid supplied into the sump toward the racks so as to clean the dishes, and a drain device discharging waste wash fluid resulting from the washing of the dishes. The wash fluid spray device includes nozzle devices arranged to face the racks and a cleaning pump pumping the wash fluid contained the sump into the nozzle devices. Each of the nozzle devices has a number of nozzles through which wash fluid can be sprayed at high pressure. 
     The nozzles may easily get clogged with impurities during a dishwashing operation, as wash fluid is recycled in order to reduce the consumption of wash fluid, and recycled wash fluid is highly likely to contain impurities. However, once the nozzles are clogged, the performance of the dishwasher deteriorates. In addition, if impurities that clog the nozzles become rotten, an offensive odor may be emitted from the washing tub. Impurities contained in recycled wash fluid may be filtered out to some extent by providing a filter between the sump and the nozzle device. However, since the performance of the filter is limited, it is almost impossible to completely filter out impurities from wash fluid. 
     It may be difficult to determine whether the nozzles of a dishwasher are clogged, and thus, it is difficult to address the problems associated with clogged nozzles in a timely manner. In addition, in order to clean the nozzles, the dishwasher may need to be disassembled and then reassembled once the cleaning of the nozzles is complete. Thus, it is very difficult and time-consuming to clean the nozzles. 
     SUMMARY 
     A dishwasher and a method of controlling a dishwasher are provided, in which it can be precisely determined whether nozzles are clogged, and in which clogged nozzles can be easily cleaned. 
     A method of controlling a dishwasher as embodied and broadly described herein may include pumping wash water contained below a washing tub by pumping a washing pump, and washing dishes loaded in the washing tub by spraying the pumped wash water through a plurality of nozzles; and unclogging the nozzles by terminating the operation of the washing pump for a predefined amount of time and then resuming the operation of the washing pump. 
     A dishwasher as embodied and broadly described herein may include a washing tub in which dishes are loaded and washed; a sump which is disposed below the washing tub and contains wash water; a washing pump which pumps the wash water out of the sump; a plurality of nozzles which spray the wash water pumped by the washing pump onto the dishes; and a control unit which unclogs the nozzles by terminating the operation of the washing pump for a predefined amount of time and then resuming the operation of the washing pump. 
     In a dishwasher and a method as embodied and broadly described herein, it is possible to quickly and precisely determine, during the washing of dishes, whether nozzles are clogged with impurities contained in wash water. In addition, it is possible to easily address the problems associated with clogged nozzles simply by terminating the operation of a washing pump for a predefined amount of time and then resuming the operation of the washing pump. 
     Moreover, it is possible to prevent the performance of a dishwasher from deteriorating due to clogged nozzles and to improve user convenience by automatically determining whether there are clogged nozzles during the washing of dishes and unclogging the nozzles if the nozzles are determined to be clogged. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of embodiments as broadly described herein will become more apparent by describing in detail features thereof with reference to the attached drawings in which: 
         FIG. 1  is a perspective view of an exemplary dishwasher according to an embodiment as broadly described herein; 
         FIG. 2  is a cross-sectional view of the dishwasher shown in  FIG. 1 ; 
         FIG. 3  is a block diagram of the dishwasher shown in  FIG. 1 ; 
         FIG. 4  is a flowchart of a method of controlling a dishwasher according to an exemplary embodiment as broadly described herein; and 
         FIG. 5  is a flowchart of a method of controlling a dishwasher according to another exemplary embodiment as broadly described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a dishwasher  1  includes a cabinet  2 , which forms the exterior of the dishwasher  1 , a washing tub  4 , which is disposed in the cabinet  2  and has a space for washing dishes loaded therein, a plurality of rack assemblies  6  and  8 , which are movably disposed in the washing tub  4  to hold dishes, and a wash fluid spray device  10 , which is disposed in the washing tub  4  and sprays wash fluid onto dishes held by the rack assemblies  6  and  8 . 
     Each of the cabinet  2  and the washing tub  4  has an opening at the front, and thus, dishes can be loaded onto the rack assemblies  6  and  8  in the tub  4  through the openings of the cabinet  2  and the washing tub  4 . A door  12  is disposed so as to be able to open or close the cabinet  2 , for example, in a drop-down manner. A detergent supply device  14  is disposed on a rear surface of the door  12  to supply detergent into the washing tub  4 . A manipulation device  16  is disposed at an upper part of the front of the door  12  to allow a user to control the operation of the dishwasher  1 . The manipulation device  16  includes a plurality of switches  16   a  and  16   b . The user may choose and set a dishwashing program by manipulating one of the switches  16   a  and  16   b.    
     Referring to  FIGS. 2 and 3 , a sump  18  is disposed below the washing tub  4 . The sump  18  contains wash fluid. A heating device (not shown) is disposed in the sump  18  and heats the wash fluid contained in the sump  18 . A sheath heater having excellent watertight properties may be used as the heating device. A water level detector  20  is disposed below the sump  18 . The water level detector  20  includes an air chamber  21 , which is connected to a lower part of the sump  18  and is filled with air, a pressure sensor  22 , which is disposed above the sump  18 , and an air hose  23 , which connects the pressure sensor  22  and the air chamber  21  and transfers wash fluid contained in the sump  18  to the pressure sensor  22  with the use of air. As the fluid level in the sump  18  increases, the pressure applied on air in the air chamber  21  by the wash fluid contained in the sump  18  increases. On the other hand, as the fluid level in the sump  18  decreases, the pressure applied on air in the air chamber  21  decreases. A variation in the air pressure in the air chamber  21  is transmitted to the pressure sensor  22  by the air in the air hose  23 . The pressure sensor  22  may detect the fluid level in the sump  18  based on a variation in the air pressure in the air chamber  21 . 
     Referring to  FIG. 3 , a fluid supply device  24  is connected to a first side of the sump  18 . The fluid supply device  24  supplies clean wash fluid provided by an external source into the sump  18 . A drain device  26  is connected to a second side of the sump  18 . The drain device  26  discharges wash fluid used to clean dishes from the dishwasher  1 . The fluid supply device  24  includes a fluid supply path (not shown) connecting the first side of the sump  18  to the external source and a fluid supply valve (not shown) disposed on the supply path. The supply of wash fluid into the sump  18  may be controlled by opening or closing the supply valve. The drain device  26  includes a drain path (not shown) disposed between the second side of the sump  18  and the outside of the dishwasher  1  and a drain pump (not shown) disposed on the drain path. The wash fluid contained in the sump  18  may be pumped out of the dishwasher  1  by the drain pump. 
     Referring to  FIGS. 1 and 2 , the rack assemblies  6  and  8  include a first rack assembly  6  disposed in a lower part of the washing tub  4  so as to be able to be withdrawn from the washing tub  4  and a second rack assembly  8  disposed in an upper part of the washing tub  4  so as to be able to be withdrawn from the washing tub  6 . The first rack assembly  6  includes a first rack  6   a  and a plurality of wheels  6   b . The first rack  6   a  is disposed in the washing tub  4  such that both lateral sides of the first rack assembly  6  can slide along corresponding inner surfaces of the washing tub  4 . The first rack  6   a  may hold dishes therein. The wheels  6   b  are disposed under the first rack  6   a  and roll along the bottom surface of the washing tub  4  and the rear surface of the door  12 . The second rack assembly  8  includes a second rack  8   a  and guide rails  8   b . The second rack  8   a  is disposed above the first rack  6   a  and may hold dishes therein. The guide rails  8   b  are disposed on both sides of the second rack  8   a  and support the second rack  8   a  so that the second rack  8   a  can move back and forth. 
     Referring to  FIGS. 1 and 2 , the wash fluid spray device  10  includes a washing pump  30 , which is connected to the sump  18  and pumps wash fluid into the sump  18 , a plurality of nozzle devices  32  and  34 , which spray the wash fluid pumped by the washing pump  30  onto the dishes held by the first and second rack assemblies  6  and  8 , and a wash fluid flow path  36 , which is formed between the washing pump  30  and the nozzle devices  32  and  34 . The nozzle devices  32  and  34  include a first nozzle device  32 , which is rotatably disposed below the first rack  6   a  and sprays wash fluid onto the dishes held by the first rack  6   a , and a second nozzle device  34 , which is rotatably disposed below the second rack  8   a  and sprays wash fluid onto the dishes held by the second rack  8   a.    
     The first nozzle device  32  includes a plurality of first nozzles  32   a , which are formed on the top surface of the first nozzle device  32  and face the first rack  6   a . Likewise, the second nozzle device  34  includes a plurality of second nozzles  34   a , which are formed on the top surface of the second nozzle device  34  and face the second rack  8   a . Thus, when wash fluid is pumped out of the sump  18  by the washing pump  30 , the wash fluid flows into the first and second nozzle devices  32  and  34  through the wash fluid flow path  36 , and is sprayed onto the dishes held by the first and second racks  6   a  and  8   a  at high pressure. 
     Referring to  FIGS. 2 and 3 , a controller  38  is disposed at the door  12  or the cabinet  2 . The controller  38  controls the operation of the dishwasher  1 . The controller  38  includes a timer  40 , which measures the operating time of the dishwasher  1 . In the exemplary embodiment of  FIGS. 1 through 3 , the controller  38  may be disposed in an upper part of the door  12 . A drying device  42  is disposed between the cabinet  2  and the washing tub  4  and supplies dry air into the washing tub  4 . The drying device  42  includes a blower, which blows external air into the washing tub  4  and discharges air from the washing tub  4 , and a heater, which heats air injected into the washing tub  4  by the blower. 
     A method of controlling the dishwasher  1  shown in  FIGS. 1-3  will hereinafter be described in detail. 
     The door  12  is pulled down so as to open the washing tub  4 , and the first and second racks  6   a  and  8   a  of the first and second rack assemblies  6  and  8  are withdrawn from the washing tub  4 . Thereafter, dishes are placed on each of the first and second racks  6   a  and  8   a , and the first and second racks  6   a  and  8   b  are put back in the washing tub  4 . Thereafter, the door  12  is closed so as to close the washing tub  4 . 
     Thereafter, a washing program is chosen by manipulating the manipulation unit  16  at the door  12 , and the dishwasher  1  is operated. The chosen washing program is input to the controller  38 , and the controller  38  controls the operation or the dishwasher  1  according to the chosen washing program. 
     Referring to  FIG. 4 , the controller  38  drives the fluid supply device  24  and thus supplies clean wash fluid into the sump  18  (S 1 ). If wash fluid is supplied into the sump  18  to a predefined water level, the operation of the water supply device  24  is terminated, and a washing operation is performed on the dishes by driving the heating device in the sump  18  and the wash water spray device  10 . More specifically, the wash water contained in the sump  18  is sprayed onto the dishes by the wash water spray device  10 . The heating device heats the wash water in the sump  18 , thereby improving the dishwashing performance of the wash water spray device  10 . During operation S 2 , detergent may be supplied into the washing tub  4  by driving the detergent supply device  14 . 
     Once the washing operation is complete, the controller  38  compares the time taken to wash the dishes with a first set time (S 3 ). If the time taken to wash the dishes is greater than the first set time, the controller  38  terminates the operations of the heating device and the spray device  10 , and drains the sump  18  by driving the drain device  26  (S 4 ). Thereafter, the controller  38  drives the supply device  24  and thus supplies clean wash fluid again into the sump  18 . Then, the controller  38  drives the spray device  10  and thus rinses the dishes with clean wash fluid (S 5 ). During the rinsing of the dishes, the wash fluid used to rinse the dishes may be heated by driving the heating device, and a rinsing agent may be supplied into the washing tub  4  by driving the detergent supply device  14 . 
     Once the rinsing of the dishes is complete, the controller  38  terminates the operations of the heating device and the spray device  10 , and drains the sump  18  by driving the drain device  26  (S 6 ). Thereafter, the controller  38  supplies hot air into the washing tub  4  by driving the drying device  42  (S 7 ). As a result, the dishes in the washing tub  4  are dried by the hot air. Thereafter, the controller  38  terminates the operation of the drying device  42 , and thus, the operation of the dishwasher  1  is complete. 
     If the time taken to wash the dishes is less than the first set time, the controller  38  measures the fluid level in the sump  18  (S 9 ) and compares the measured fluid level to a reference fluid level to determine whether the first nozzles  32   a  and the second nozzles  34   a  are clogged (S 10 ). If the measured level is greater than the reference level, it is determined that the first nozzles  32   a  and/or the second nozzles  34   a  are clogged, the controller  38  terminates the operation of the washing pump  30  for a second set time (S 11 ) and then resumes the operation of the washing pump  30  in order to unclog the first nozzles  32   a  and/or the second nozzles  34   a  (S 12 ). 
     More specifically, if the fluid level in the sump  18  exceeds a reference fluid level (S 10 ), the controller  38  determines that the first nozzles  32   a  and/or the second nozzles  34   a  are not allowing adequate flow of fluid therethrough and thus are clogged. The reference fluid level may be a level at which neither the first nozzles  32   a  nor the second nozzles  34   a  are clogged. 
     That is, if none of the first nozzles  32   a  and the second nozzles  34   a  are clogged and the wash fluid spray device  10  operates normally, the fluid level in the sump  18  may gradually decrease due to the consumption of wash fluid by the spray device  10 . Thus, the reference fluid level may be a lowest fluid level in the sump  18  due to the consumption of the wash fluid by the spray device  10 . If some of the first nozzles  32   a  and/or the second nozzles  34   a  are clogged, the amount or wash fluid sprayed through the first nozzles  32   a  and the second nozzles  34   a  may decrease. Thus, the fluid level in the sump  18  may be higher than the reference level because of a reduction in the amount of wash fluid consumed by the spray device  10 . 
     If the fluid level in the sump  18  exceeds the reference level, the controller  38  terminates the operation of the washing pump  30  for the second set time (S 11 ), and then resumes the operation of the washing pump  30  (S 12 ), thereby removing impurities that clog the first nozzles  32   a  and the second nozzles  34   a  with high-pressure wash fluid as the operation of the washing pump  30  is re-initiated (S 12 ). 
     Thereafter, the method returns to operation S 2 . If the impurities that clog the first nozzles  32   a  and the second nozzles  34   a  are not completely removed by operations S 11  and S 12 , operations S 11  and S 12  may be performed again. During operation S 2 , it may be continuously monitored whether the first nozzles  32   a  and the second nozzles  34   a  are clogged. Operations S 11  and S 12  may be performed repeatedly until the fluid level in the sump  18  decreases below the reference water level. 
       FIG. 5  is a block diagram of a dishwasher according to another exemplary embodiment. Referring to  FIG. 5 , the dishwasher includes a washing tub, which holds dishes therein and contains wash fluid, a washing pump  130 , which pumps the wash fluid out of the washing tub  4 , a plurality of nozzles, which spray the wash fluid pumped by the washing pump  130  onto the dishes, and a controller  138 , which terminates the operation of the washing pump  130  for a predefined amount of time and then resumes the operation of the washing pump  130  in order to unclog the nozzles as necessary. The dishwasher may also include a clogged nozzle detector  110 , which detects clogged nozzles during the washing of the dishes in the tub by the washing pump  130 . If the clogged nozzle detector  110  determines that the nozzles are clogged, the controller  138  terminates the operation of the washing pump  130  for the predefined amount of time and then resumes the operation of the washing pump  130 . More specifically, the clogged nozzle detector  110  determines whether the nozzles are clogged, and transmits a sensing signal indicating whether the nozzles are clogged to the controller  138 . If the sensing signal indicates that the nozzles are clogged, the controller  138  terminates the operation of the washing pump  130  for the predefined amount of time and then resumes the operation of the washing pump  130 , thereby removing impurities that clog the nozzles. 
     The dishwasher may also include a fluid level detector  120 , which is disposed below the washing tub and measures the fluid level in the washing tub. In this case, if a measured fluid level provided by the fluid level detector  120  exceeds a reference fluid level, the controller  138  may determine that the nozzles are clogged. The operation of the controller  138  when it is determined that the nozzles are clogged, the controller  138  is the same as that described above with reference to  FIGS. 3 and 4 , and thus, a detailed description thereof will be omitted. The reference fluid level may be a level at which none of the nozzles are clogged. The controller  138  may terminate and then resume the operation of the washing pump  130  more than one time until the nozzles are completely unclogged. Therefore, it is possible to prevent dishes from being improperly cleaned due to clogged nozzles. In addition, it is possible to effectively clean dishes by periodically monitoring whether there are clogged nozzles and cleaning clogged nozzles. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” “certain embodiment,” “alternative embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment as broadly described herein. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, numerous variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.