Abstract:
Disclosed is a dishwasher, which prevents a washing cycle from being carried out in an insufficient state of washing water caused by the continuous discharge of the washing water due to a siphon action, and a method of controlling the dishwasher. The method includes draining washing water from the dishwasher; supplying the washing water to the inside of the dishwasher; and temporarily stopping the supply of the washing water for a designated time between the drain of the washing water and the supply of the washing water.

Description:
This application claims the benefit of Korean Patent Application No. 10-2007-0106223, filed on Oct. 22, 2007, which is hereby incorporated by reference as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dishwasher and a method of controlling the same, and more particularly, to a method of controlling supply and drain of washing water in a dishwasher. 
     2. Discussion of the Related Art 
     Dishwashers are electric home appliances for kitchens, which separate residue of food, such as grains of boiled rice, from dishes using high-pressure washing water, and thus, wash the dishes. 
     In general, a dishwasher includes a main body forming an external appearance of the dishwasher, a washing tub provided in the main body to form a washing space, a sump provided under the washing tub to supply and collect washing water, and spray arms to spray the washing water supplied from the sump to dishes. 
     The sump includes a water supply channel and a water supply valve to supply the washing water to the sump, a drain channel and a drain pump to drain the washing water in the sump, a pump to supply the washing water stored in the sump to the spray arms at a designated pressure, and a heater to heat the washing water stored in the sump. 
     An air guide to maintain the pressure in a washing tub and the external pressure equally is provided in an washing tub, and a water level sensor to sense a level of the washing water stored in the sump is provided in the sump. 
     Hereinafter, supply and drain of washing water in the above-described dishwasher will be described. 
     First, washing water is supplied to the sump of the dishwasher through the water supply channel and the water supply valve, and when the washing water reaches a designated level in the sump, the supply of the washing water is stopped. 
     After the completion of the supplying of the washing water to the sump, the pump is operated, and thus, pumps the washing water in the sump to the spray arms, and the spray arms spray the washing water onto dishes located in the washing tub to perform a washing cycle (or a rinsing cycle). 
     When the washing cycle has been completed, the washing water used in the washing cycle is drained to the outside of the dishwasher through the drain channel and the drain pump. Then, the drained washing water level is sensed by the water level sensor. 
     When the water level sensor senses that the washing water has been completely drained from the sump, the drain pump is further driven for a designated time to drain any remaining washing water, which has not been sensed by the water level sensor, and then is stopped. 
     In order to perform an additional washing cycle or rinsing cycle, the washing water is supplied again to the sump. This process may be repeatedly performed during dish washing (or a rinsing cycle). 
     While the drain of the washing water is converted into the supply of the washing water, as described above, the supplied washing water may be continuously drained through the drain channel. 
     For example, during the supply of the washing water, power supplied to the drain pump is cut off. However, the washing water supplied to the sump is drained through the drain channel due to inertial operation of the drain pump, which was operated during the draining of the washing water. 
     Further, in a case that an end terminal of the drain channel is located at a position lower than a level of the washing water in the sump, the washing water supplied to the sump may be continuously drained due to the above-described drain action caused by the inertial operation of the drain pump and a siphon action generated between the sump and the drain channel. 
     In a case that a part of the washing water supplied to the sump is drained through the drain channel, as described above, the washing water supplied to the sump is insufficient, and thus, a washing (or rinsing) efficiency is lowered. 
     Further, in a case that the washing (or rinsing) cycle is performed under a condition that the washing water is excessively insufficient, an excessively high load is applied to the pump pumping the washing water to the spray arms and the heater heating the washing water, and thus, components of the dishwasher may be damaged. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a dishwasher and a method of controlling the same. 
     One object of the present invention is to provide a dishwasher, in which supply and drain of washing water are improved, and a method of controlling the dishwasher. 
     To achieve this object and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a dishwasher includes a sump; a water supply device to supply washing water to the inside of the sump; a drain device to drain the washing water in the sump to the outside of the dishwasher; and a control device to stop the supply of the washing water for a designated time after the operation of the drain device has been finished. 
     Preferably, the control device stops the supply of the washing water by stopping the operation of the dishwasher. 
     Preferably, the control device stops the supply of the washing water by stopping the operation of the water supply device. 
     Preferably, the control device stops the supply of the washing water for a shorter time than the operating time of the water supply device. 
     Preferably, the control device stops the supply of the washing water for a shorter time than the operating time of the drain device. 
     Preferably, the dishwasher further comprises a water level sensor to sense the level of the washing water drained by the drain device, and the control device further operates the drain device for a designated time to drain the remainder of the washing water, which is not drained, according to the sensing of the water level sensor. 
     In another aspect of the present invention, a method of controlling a dishwasher includes draining washing water from the dishwasher; supplying the washing water to the inside of the dishwasher; and temporarily stopping the supply of the washing water for a designated time between the drain of the washing water and the supply of the washing water. 
     Preferably, the stoppage of the supply of the washing water is carried out by stopping the operation of a water supply valve. 
     Preferably, the stoppage of the supply of the washing water is carried out by stopping the operation of the dishwasher. 
     Preferably, the stoppage of the supply of the washing water is carried out for a shorter time than a water supply time, for which the washing water is supplied to the dishwasher. 
     Preferably, the stoppage of the supply of the washing water is carried out for a shorter time than a drain time, for which the washing water is drained from the dishwasher. 
     Preferably, wherein the stoppage of the supply of the washing water includes sensing the level of the drained washing water; and additionally draining the remainder of the washing water, which is not drained, after the sensing of the level of the drained washing water. 
     In another aspect of the present invention, a method of controlling a dishwasher, which has supplying washing water to the inside of the dishwasher; washing dishes in the dishwasher using the washing water; and draining the washing water from the dishwasher, includes temporarily stopping the supply of the washing water for a designated time between the drain of the washing water and the supply of the washing water when the drain of the washing water is converted into the supply of the washing water to repeatedly perform the respective operations. 
     Preferably, the stoppage of the supply of the washing water is carried out by stopping the operation of a water supply valve. 
     Preferably, the stoppage of the supply of the washing water is carried out by stopping the operation of the dishwasher. 
     Preferably, the stoppage of the supply of the washing water is carried out for a shorter time than a water supply time, for which the washing water is supplied to the dishwasher. 
     Preferably, the stoppage of the supply of the washing water is carried out for a shorter time than a drain time, for which the washing water is drained from the dishwasher. 
     Preferably, the stoppage of the supply of the washing water includes sensing the level of the drained washing water; and additionally draining the remainder of the washing water, which is not drained, after the sensing of the level of the drained washing water. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  is a perspective view illustrating a dishwasher in accordance with an embodiment of the present invention; 
         FIG. 2  is a longitudinal-sectional view illustrating the internal structure of the dishwasher in accordance with the embodiment of the present invention; 
         FIG. 3  is a block diagram illustrating the configuration of the dishwasher in accordance with the embodiment of the present invention; 
         FIG. 4  is a flow chart illustrating the operation of the dishwasher in accordance with the embodiment of the present invention; 
         FIG. 5  is a flow chart illustrating the supply of washing water and the drain of the washing water during the operation of the dishwasher in accordance with the embodiment of the present invention; and 
         FIG. 6  is a graph illustrating a variation of the level of the washing water in a sump according to the operation of the dishwasher in accordance with the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     Hereinafter, a dishwasher in accordance with a preferred embodiment of the present invention will be described in detail with reference to accompanying drawings. 
       FIG. 1  is a perspective view illustrating a dishwasher in accordance with an embodiment of the present invention. 
     With reference to  FIG. 1 , the dishwasher of the present invention includes a case  1  forming the an external appearance of the dishwasher and provided with an opening, through which dishes are put into the case  1 , a door  2  to open and close the opening of the case  1 , and a control panel  3  provided at an external surface of the case  1  to display and control operation of the dishwasher. 
     The control panel  3  includes a power switch  5  to turn on/off power of the dishwasher, a function manipulation unit  7  to control the operation of the dishwasher by the manipulation of a user, and a display unit  8  to display setting and operating states of the dishwasher. Further, a door handle  4  used to open and close the door  2  is further provided on the door  2 . 
       FIG. 2  is a longitudinal-sectional view illustrating internal structure of the dishwasher in accordance with the embodiment of the present invention. 
     With reference to  FIG. 2 , the internal structure of the dishwasher of the present invention will be described. 
     In the dishwasher, a washing tub  18  providing a space, in which the dishes are washed, a sump  16  formed under the washing tub  18  to store washing water to wash the dishes, and a plurality of spray arms  14 ,  15 , and  24  to receive the washing water stored in the sump  16  and spray the washing water to the dishes placed in the washing tub  18  are provided. 
     The washing tub  18  includes an upper rack  11  and a lower rack  12  to receive a plurality of dishes in the washing tub  18 . Further, the spray arms  14 ,  15 , and  24  to spray the washing water upward or downward onto the upper rack  11  and the lower rack  12  are provided below or above the upper rack  11  and the lower rack  12 . 
     An air guide  200  to cause external air and air in the washing tub  18  to communicate with each other is provided in the washing tub  18 . The inside of the washing tub  18  can be maintained in an atmospheric pressure state at any time by the air guide  200 . 
     The air guide  200  includes an air inlet  201 , through which external air is inhaled, an opening  202  that communicates with air in the washing tub  18 , and an air channel  203  connecting the air inlet  201  and the opening  202 . 
     Since the inside of the washing tub  18  can be maintained in the atmospheric pressure state at any time by the air guide  200 , it is possible to prevent the pressure in the washing tub  18  from being raised due to steam or high-temperature air. Thus, a danger of explosion generated when the pressure in the washing tub  18  is raised, in particular a possibility of inflicting an injury on a user due to high pressure in the washing tub  18  and high-temperature washing water when the user opens the door  2  during the operation of the dishwasher, is prevented. 
     The sump  16  includes a water supply channel  33  located in a lower portion of the washing tub  18  to supply the washing water, a drain channel  25  to drain the washing water, which has completed the washing and rinsing of the dishes, and a washing water channel  19  to provide the washing water stored in the sump  16  to the respective spray arms  14 ,  15 , and  24 . An inflow hole  17  to collect the washing water after the washing or rinsing of the dishes is formed through an upper surface of the sump  16 . 
     The water supply channel  33  serves to supply the washing water, supplied from an external water supply source (not shown), such as a tap, to the sump  16 . The water supply channel  33  is provided with a water supply valve  40  to adjust the supply of the washing water. Further, the water supply channel  33  is further provided with a water level sensor  34  to sense an amount of the washing water supplied to and stored in the sump  16 . 
     The drain channel  25  serves to drain the washing water in the sump  16 , which has completed the washing and rinsing of the dishes. The drain channel  25  is provided with a drain pump  50  to drain the washing water stored in the sump  16 . The drain channel  25  is preferably formed in a reversed U shape passing through a higher position than a level of the washing water in the sump  16 , and this shape of the drain channel  25  prevents a siphon action due to the drain channel  25 . 
     The washing water channel  19  serves to provide the washing water, supplied to the sump  16  through the water supply channel  33  or collected in the sump  16  through the inflow hole  17 , to the spray arms  14 ,  15 , and  24 . The washing water channel  19  is provided with a pump (not shown) to supply the washing water to the spray arms  14 ,  15 , and  24  at a designated pressure. 
     The water supply valve  40  of the water supply channel  33  and the drain pump  50  of the drain channel  25  are controlled by a control device  100 , and the control device  100  controls the water supply valve  40  and the drain pump  25  according to the amount of the washing water in the sump  16  sensed by the water level sensor  34  (with reference to  FIG. 3 ). 
     Hereinafter, operation of the dishwasher in accordance with an embodiment of the present invention will be described. Respective elements, which will be described later, will be understood with reference to the above description and  FIG. 1 . 
     The dishwasher in accordance with the embodiment sequentially or selectively performs preliminary washing, main washing, rinsing, heat-rinsing, and drying cycles to wash dishes. Hereinafter, a washing cycle will be exemplarily described. However, the present invention is not limited to the washing cycle, but may be applied to other cycles, such as a rinsing cycle including a process of converting the drain of the washing water into the supply of the washing water. 
     First, the operation of the dishwasher in accordance with the embodiment will be described. When a user wants to perform washing of dishes, the user places the dishes on the racks  11  and  12 , and closes the door  2 . 
     Thereafter, when the user selects a desired washing state of the dishes and starts the operation of the dishwasher by manipulating the function manipulation unit  7  provided on the control panel  3 , the operation of the dishwasher is carried out under a condition that the operating state of the dishwasher is displayed on the display unit  8  of the control panel  3 . 
     Hereinafter, the operation of the dishwasher focusing on the flow of the washing water in the washing tub  18  will be described.  FIG. 4  is a flow chart illustrating the operation of the dishwasher in accordance with the embodiment of the present invention. 
     With reference to  FIG. 4 , when the operation of the dishwasher is started, the control device  100  (with reference to  FIG. 3 ) opens the water supply valve  40 , and thus washing water is supplied to the inside of the sump  16  through the water supply channel  33  (operation S 110 ). 
     Thereafter, the washing water supplied to the inside of the sump  16  is supplied to the spray arms  14 ,  15 , and  24  by the pump (not shown), and is sprayed onto dishes loaded on the racks  11  and  12  by the spray arms  14 ,  15 , and  24 , thus washing the dishes (operation S 120 ). 
     The washing water sprayed from the spray arms  14 ,  15 , and  24  washes the dishes placed on the racks  11  and  12 , and then is dropped down and collected in the sump  16  through the inflow hole  17  formed through the upper surface of the sump  16 . The washing water collected in the sump  16  is supplied again to the spray arms  14 ,  15 , and  24  through the washing water channel  19  by the pump, and washes the dishes. 
     Thereafter, when the washing of the dishes by the washing water sprayed by the spray arms  14 ,  15 , and  24  has been completed, the drain pump  50  is driven and thus discharges the washing water in the sump  16  to the outside. That is, the drain pump  50  is operated by the control device  100 , and thus discharges the washing water collected in the sump  16  to the outside through the drain channel  25  (operation S 130 ). 
     Then, the control device  100  determines whether or not the washing cycle has been completed so as to repeatedly perform the above-described process (operation S 140 ). 
     In case that the washing cycle has not been completed, the drain of the washing water and the supply of the washing water are controlled so as to repeatedly perform the supply of the washing water, the washing of the dishes, and the drain of the washing water (operation S 150 ). 
     On the other hand, in case that the washing cycle has been completed, the heater on the bottom surface of the washing tub  18  is driven, and thus dries the dishes (operation S 160 ). Thereby, the operation of the dishwasher is completed. 
     In case that the washing cycle has not been completed as a result of the determination of operation S 140 , the supply of the washing water is performed after the drain of the washing water, and then the washing of the dishes and the drain of the washing water are repeated. 
     Hereinafter, a process of converting the drain of the washing water into the supply of the washing water (operation S 150 ) to repeatedly perform the washing cycle will be described. 
       FIG. 5  is a flow chart illustrating the supply of washing water and the drain of the washing water during the operation of the dishwasher in accordance with the embodiment of the present invention. 
     First, the control device  100  drives the drain pump  50  to drain the washing water stored in the sump  16 , and thus allows the washing water in the sump  16  to be drained (operation  151 ). 
     At this time, the water level sensor  34  senses the level of the washing water drained from the sump  16  and transmits the sensed level to the control device  100 , and the control device  100  determines whether or not the drain of the washing water in the sump  16  has been completed (operation  152 ). 
     In a case that it is determined the washing water in the sump  17  has not been completely drained by the sensing of the water level sensor  34 , the control device  100  continuously drives the drain pump  50  such that the drain of the washing water in the sump  17  can be completed. 
     In a case that it is determined the washing water in the sump  17  has been completely drained by the sensing of the water level sensor  34 , the control device  100  further drives the drain pump  50  for a designated time. That is, in order to drain any remaining washing water in the sump  16 , which has not been sensed by the water level sensor  34 , the drain pump  50  is further driven for the designated time (operation S 153 ). 
     Here, the discharged washing water serves to prevent the washing water in the sump  16  from being discharged due to a siphon action caused by the communication of external air and internal air through the air inlet  201  of the air guide  200 . 
     However, the above process cannot completely prevent the siphon action through the air inlet  201 . 
     Therefore, when the control  100  stops the drain pump  50  and simultaneously opens the water supply valve  40 , the control device  100  cannot prevent the supplied washing water from being directly discharged due to the inertial operation of the drain pump  50  and the siphon action. For this reason, the supply of the washing water is stopped for a designated time so as to completely stop the inertial operation of the drain pump  50  (operation S 154 ). 
     Preferably, the designated time, i.e., a stopping time (T 2 ), for which the supply of the washing water is stopped, is shorter than the driving time (T 3 ) of the water supply valve  40  and the driving time (T 1 ) of the drain pump  50  (with reference to  FIG. 6 ). 
     The reason why the stopping time (T 2 ) of the supply of the washing water is shorter than the driving time (T 3 ) of the water supply valve  40  and the driving time (T 1 ) of the drain pump  50  is that the excessively long stopping time (T 2 ) causes an increase of the overall time of the dishwasher taken to perform the cycle. 
     The stoppage of the supply of the washing water may be carried out by closing the water supply valve  40 . Alternately, the stoppage of the supply of the washing water may be carried out by temporarily stopping the overall operation of the dishwasher. 
     After the stopping time (T 2 ) of the supply of the washing water has elapsed, the control device  100  repeatedly performs the supply of the washing water (operation S 110 ), the washing of the dishes (operation S 120 ), and the drain of the washing water (operation S 130 ), thus performing a dish washing process. 
     The above embodiment describes that the supply of the washing water is stopped temporarily between the drain of the washing water and the supply of the washing water during the washing of dishes. However, the method of the present invention is not limited to the washing of the dishes, but may be applied to any time between the drain of the washing water and the supply of the washing water. 
     As described above, as the supply of the washing water is stopped for a designated time between the draining of the washing water and the supply of the washing water during the washing of dishes, it is possible to prevent the washing water supplied to the sump  16  from being drained due to a siphon action relating to internal operation of the drain pump  50 . 
     Further, as the draining of the washing water is prevented, it is possible to prevent an excessive large load from being applied to the pump and the heater of the dishwasher due to insufficiency of the washing water. Moreover, as the supply of the washing water is stopped for a designated time between the draining of the washing water and the supply of the washing water, noise generated during an overall operation of the dishwasher is reduced. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.