Patent Publication Number: US-7722725-B2

Title: Dishwasher and sump assembly thereof

Description:
This application claims the benefit of the Korean Application No. P2004-75929 filed on Sep. 22, 2004, which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dishwasher, and more particularly, to a sump assembly of a dishwasher. 
     2. Discussion of the Related Art 
     Generally, a dishwasher is a home appliance for washing dishes or tableware automatically by spraying water of high pressure on the tableware using spray nozzles. A dishwasher basically consists of at least one rack provided within a tub to have dishes put thereon, a sump storing water therein, and at least one sprayer for spraying the water on the dishes. 
     In the general dishwasher, the water is pumped from the sump to the sprayer and the pumped water is sprayed toward the dishes for washing. The sprayed water is collected into the sump to be re-supplied to the sprayer so that the re-supplied water can be sprayed on the dishes. 
     However, as the water is repeatedly used, a quantity of contaminant involved in the water gradually increases to lower washing performance of the dishwasher. Specifically, it is highly probable that a passage within the sump is blocked by the contaminant. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a sump assembly of a dishwasher that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a sump assembly of a dishwasher, by which contaminant or garbage can be removed from water. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a sump assembly of a dishwasher according to the present invention includes a sump housing storing water therein, a pump coupled with the sump housing to pump the water, a guide assembly provided within the sump housing to guide the pumped water to a sprayer, and a drain chamber configured to filter contaminant from the water drained from the guide assembly. 
     Preferably, the drain chamber is configured to deposit the contaminant on a bottom of the drain chamber. And, the contaminant has a relatively heavy weight. For such a filtering function, the drain chamber always communicates with the guide assembly and the guide assembly communicates with the guide assembly only while dishes are washed. And, the water returns to the guide assembly via the drain chamber. Moreover, the drain chamber is provided within the sump housing. Specifically, the drain chamber is situated below the guide assembly. Namely, the drain chamber is configured to allow the water to flow downwardly to the drain chamber from the guide assembly. And, the drain chamber is configured to allow the water to flow upwardly from the drain chamber to the guide assembly. 
     Preferably, the drain chamber is configured to externally drain the water within the sump assembly. In this case, the drain chamber externally discharges the water within the sump housing and the guide assembly. And, the drain chamber is connected to a drain pump configured to drain the water from the drain chamber. Moreover, the drain chamber additionally communicates with the sump housing if the water is discharged from the dishwasher. 
     Preferably, the sump assembly further includes a valve configured to allow the drain chamber to communicate with the sump housing selectively. The valve allows the drain chamber to communicate with the sump housing while the water is drained from the dishwasher. The valve isolates the drain chamber from the sump housing while dishes are washed. Specifically, the valve is provided to the drain chamber to open/close an opening communicating with the sump housing selectively. More preferably, the valve is a check valve. More preferably, the valve includes a valve body opening/closing an opening provided to the drain chamber and a fixing portion fixing the valve body to the drain chamber. And, the valve body comprises a protrusion tightly fitted in the opening. 
     Preferably, the guide assembly is configured to bypass a portion of the pumped water to the drain chamber. More preferably, the guide assembly further includes a soil chamber communicating with the drain chamber to additionally filter the contaminant from the water drained from the drain chamber. 
     Preferably, the sump assembly further includes a cover covering the sump housing and the guide assembly. And, the cover includes at least one aperture guiding the water sprayed on dishes to the sump housing. 
     In another aspect of the present invention, a dishwasher includes a housing, a tub provided within the housing to receive tableware therein, a sprayer provided within the tub to spray water on the tableware, and a sump assembly including a sump housing storing the water therein, a pump coupled with the sump housing to pump the water, a guide assembly provided within the sump housing to guide the pumped water to a sprayer, and a drain chamber configured to filter contaminant from the water drained from the guide assembly. 
     Therefore, the contaminant can be completely removed from the water. And, the washing efficiency is not lowered despite repeated use of the 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 cross-sectional diagram of a dishwasher according to the present invention; 
         FIG. 2  is an exploded diagram of a sump assembly of a dishwasher according to the present invention; 
         FIG. 3  is an exploded diagram of a drain chamber within a sump assembly according to the present invention; 
         FIG. 4A  is a cross-sectional diagram of a drain chamber operating in the process of washing; and 
         FIG. 4B  is a cross-sectional diagram of a drain chamber operating in the process of draining. 
     
    
    
     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. 
       FIG. 1  is a cross-sectional diagram of a dishwasher according to the present invention. 
     Referring to  FIG. 1 , a tub  20  is provided within a case  10  forming an exterior of a dishwasher, and a door  15  opening/closing the tub  20  is provided to one side of the case  10 . A washing chamber  25  for accommodating tableware or dishes therein is provided within the tub  20 . And, at least one rack is provided to the washing chamber  25  so that the dishes can be put thereon. For instance, the rack, as shown in  FIG. 1 , includes an upper rack  31  provided to an upper part of the washing chamber  25  and a lower rack  35  provided to a lower part of the washing chamber  25 . 
     Moreover, at least one spray arm is provided in the vicinity of the rack within the washing chamber  25 . For instance, the spray arm, as shown in  FIG. 1 , includes an upper arm  41  arranged under the upper rack  31  and a lower arm  45  arranged under the lower rack  35 . The upper and lower arms  41  and  45  are respectively rotatable, and each of the upper and lower arms  41  and  45  includes at least one spray nozzle  43  spraying water toward the dishes. 
     A sump assembly  50  supplying water to the upper and lower arms  41  and  45  is provided within the case  10 , e.g., under the tub  20 . The sump assembly  50  is connected to the upper arm  41  via a first connecting pipe  61  and is connected to the lower arm  45  via a second connecting pipe  65 . And, the sump assembly  50  is supplied with the water from outside via a water supply pipe  70  to store the supplied water therein and selectively or simultaneously supply the water to the upper and lower arms  41  and  45  via the first and second connecting pipes  61  and  65 , respectively. A detailed configuration of the sump assembly  50  is shown in  FIG. 2 , and the sump assembly is explained in detail with reference to  FIG. 2  as follows. 
     Referring to  FIG. 2 , the sump assembly  50  includes a sump housing  100  storing water therein, a water supply pump  300  for pumping the water stored in the sump housing  100 , and a water guide assembly  500  for guiding the pumped water to the upper and lower arms  41  and  45 . And, the sump assembly  50  further includes a heater assembly  200  for heating the water, a drain pump  400  for draining the water outside, and a cover  600  covering the sump housing  100  to filter the water. 
     A recess  110  is provided to a bottom center of the sump housing  100  to store the water, and a water supply hole  120  is provided to one side of the recess  100  to be connected to the water supply pipe  70 . And, a drain chamber  900  is provided to the sump housing  100  in the vicinity of the recess  110 . 
     The drain pump  400  is loaded in a lateral side of the sump housing  100 . The drain pump  400  communicates with the drain chamber  900  and discharges the water within the recess  110 , the drain chamber  900 , and the water guide assembly  500  outside. And, the drain pump  400  includes an impeller housing  420 , a motor  410 , and an impeller  430 . 
     The impeller housing  420 , as shown in  FIG. 2 , is coupled to a lateral side of the sump housing  100  and communicates with the drain chamber  900 . The impeller housing  420  can be built in one body of the sump housing  100 . A nipple  425  is projected from a lateral side of the impeller housing  420  to be connected to a drain hose  80 . 
     The motor  410  having a shaft, with which the impeller  430  is coupled, is assembled to the impeller housing  420  so that the impeller  430  can be inserted in the impeller housing  420 . Hence, once the drain pump  400  is actuated, the water stored in the recess  110  and the water guide assembly  500  is discharged outside via the drain chamber  900 , the drain pump  400 , and the drain hose  80 . 
     The water supply pump  300  pumps the water over the heater assembly  200  to supply the water heated by the heater assembly  200  to the spray arms without heat loss. The water supply pump  300  includes a motor  310 , an impeller  320 , and an impeller housing, which is explained in detail as follows. 
     First of all, the motor  310 , as shown in  FIG. 2 , is installed at a bottom of the sump housing  100 . A shaft  311  of the motor  310  is installed to penetrate a hole  130  provided to a bottom of the recess  110 . A disposer  150  having a multitude of blades, as shown in  FIG. 2 , is assembled to the shaft  311  penetrating the bottom of the sump housing  100 . If the motor  310  is actuated, the disposer  150  is rotated to grind garbage that is contained in the water stored in the recess  110 . 
     The impeller  320  is assembled to the shaft  311  as well. The impeller  320 , as shown in  FIG. 2 , is situated over the heater assembly  200  and is rotated to pump the water. Specifically, the impeller  320  sucks the water in an axial direction and discharges the water in a radial direction. For this, the impeller  320  includes an upper plate  321 , a lower plate  323  separated from the upper plate  321  to leave a predetermined gap from each other, and a multitude of blades  325  provided between the upper and lower plates  321  and  323 . The upper plate  321  is blocked and an inlet (not shown in the drawing) is provided to a center of the lower plate  323  to have the water flow therein. A hub (not shown in the drawing) is provided to a center of the upper plate  321  and the shaft  311  is fitted in a lower end of the hub. A multitude of the curved blades  325  are provided between the upper and lower plates  321  and  323 , and an outlet  327  is provided between the blades  325  to discharge the water having flown in the impeller  320  via the inlet. 
     The impeller housing encloses the impeller  320  to guide the water moved by the impeller  320 . The impeller housing is preferably built in one body of the water guide assembly  500  instead of being formed of an independent body. In this case, the water guide assembly  500  includes a lower piece  510  and an upper piece  550 . If the upper and lower pieces  550  are assembled together, a portion of the assembly configures the impeller housing. The impeller housing is explained in detail as follows. 
     First of all, to a top surface of the lower piece  510  of the water guide assembly  500 , as shown in  FIG. 2 , provided are an inlet  335  via which the water stored in the recess  110  of the sump housing  100  flows, a lower recessed seat  331  accommodating a lower part of the impeller  320  therein, and a lower water passage  337  guiding the water pumped by the impeller  320 . The lower recessed seat  331  is provided to enclose the inlet  335 , and the inlet  335  communicates with the inlet (not shown in the drawing) of the impeller  320  situated on the lower recessed seat  331 . And, the lower water passage  337  is provided to enclose the lower recessed seat  331 . 
     To a bottom surface of the upper piece  550  of the water guide assembly  500  provided are an upper recessed seat  333  accommodating an upper part of the impeller  320  to confront the lower recessed seat  331 , an upper water passage  334  guiding the water pumped by the impeller  320  to confront the lower water passage  337 , and an outlet  551  guiding the water pumped from the upper water passage  334  to an upper surface of the upper piece  550 . The upper water passage  334  is provided to enclose the upper recessed seat  333  and the output  551  is formed at an end of the upper water passage  334 . 
     Once the motor  310  is actuated, the impeller  320  is rotated in a space defined by the lower and upper recessed seats  331  and  333 . The water stored in the recess  110  of the sump housing  100  is introduced into the impeller  320  via the inlet  335  and the impeller  320  discharges the water in a radial direction. The water discharged from the impeller  320  moves along the water passage defined by the lower and upper water passages  337  and  334  and is finally led to the top surface of the upper piece  550  of the water guide assembly  500  via the outlet  551 . A portion of the water having flown to the top surface of the upper piece  550  is selectively guided to the upper or lower arm  41  or  45  or is simultaneously guided to the upper and lower arms  41  and  45 . The water guide assembly  500  is explained in detail as follows. 
     First of all, the water guide assembly  500  includes the upper and lower pieces  550  and  510 . The upper piece  550  is provided with a valve receiving portion  553  communicating with the outlet  551 . And, first and second guide passages  557  and  555  for supplying the water to the lower and upper arms  45  and  41  are connected to the valve receiving portion  553 , respectively. In this case, the first guide passage  557  is provided to the top surface of the upper piece  550  from the valve receiving portion  553  to a center of the upper piece  550 , while the second guide passage  555  is provided to the top surface of the upper piece  550  from the valve receiving portion  553  to an edge of the upper piece  550 . 
     A diverting valve  810  is situated at the valve receiving portion  553  to guide a portion of the water flowing from the outlet  551  to the first or second guide passages  557  or  555  selectively or to the first and second guide passages  557  and  555  simultaneously. The diverting valve  810  basically communicates with the outlet  551  all the time and has a rib  811  enabling the first or second guide passage  557  or  555  to be selectively blocked. The diverting valve  810 , as shown in  FIG. 2 , is loaded in the sump housing  100  and becomes situated at the valve receiving portion  553  when the water guide assembly  500  is mounted on the sump housing  100 . For this, a hole  517  is formed at the lower piece  510  to correspond to the valve receiving portion  553  so that the diverting valve  810  and to be penetrated by the hole  517 . A driving mechanism for actuating the diverting valve  810  is provided under the sump housing  100 . The driving mechanism, as shown in  FIG. 2 , includes a step motor that can accurately control a rotational angle of the diverting valve  810 . 
     Hence, when the dishwasher washes or rinses the dishes, the diverting valve  810  is reversibly rotated by the driving mechanism. In doing so, the rib  811  selectively blocks the first or second guide passage  557  or  555 . Moreover, as the rotational angle of the diverting valve  810  is appropriately controlled so that the rib  811  may not block both of the first and second guide passages  557  and  555  to make them communicate with the outlet  551  simultaneously. Thus, the water pumped by the water supply pump  300  is supplied to the first or second guide passages  557  or  555  selectively or to the first and second guide passages  557  and  555  simultaneously. And, the water led to the first and second guide passages  557  and  555  is supplied to the upper and lower arms  45  and  41 , respectively. 
     Meanwhile, the garbage or contaminant separated from the dishes comes into flowing in the sump assembly  50  together with the water, which may result in blocking the passages within the sump assembly  50 . In the present invention, the sump assembly  50  is configured to filter the water pumped by the water supply pump  300  in part. Thereafter, the filtered water is stored again in the sump housing  100 , i.e., the recess  110 , to be supplied to the sprayers, i.e., the upper and lower arms  41  and  45 . The filtering function and its associated configuration of the sump assembly  50  are explained in detail as follows. 
     First of all, a bypass  556  communicating with the outlet  551  is provided to the top surface of the upper piece  550 . The bypass  556 , as shown in the drawing, always communicates with the outlet  551 , whereas the first and second guide passages  557  and  555  selectively communicate with the outlet  551  by the diverting valve  810 . A sensor receiving portion  559  is provided in the middle of the bypass  556 . A sensor assembly  700  is situated in the sensor receiving portion  559  to measure a degree of pollution of the water that flows in the bypass  556  by being pumped by the water supply pump  300 . 
     The sensor assembly  700 , as shown in  FIG. 2 , is loaded in the sump housing  100  to be situated at the sensor receiving portion  559  when the water guide assembly  500  is mounted on the sump housing  100 . For this, a hole  519  is provided to the lower piece  510  to correspond to the sensor receiving portion  559  and to be penetrated by the sensor assembly  700 . 
     A channel  710  communicating with the bypass  556 , as shown in  FIG. 2 , is provided to traverse a center of the sensor assembly  700 . Hence, the water introduced into the bypass  556  passes through the channel  710 . A light emitting unit (not shown in the drawing) and a light receiving unit (not shown in the drawing) are provided within the sensor assembly  700  to oppose each other by leaving the channel  710  in-between. A light emitted from the light emitting unit is passed through the water flowing in the channel  710  to arrive at the light receiving unit. Hence, the sensor assembly  700  measures the degree of pollution of the water based on the intensity of the light received by the light receiving unit. 
     The water pollution degree measured by the sensor assembly  700  is used as a basis for determining a washing time, a washing number, a rinsing time, a rinsing number, and the like. For instance, if a quantity of light arriving at the light receiving unit is very weak, it means that the water is badly polluted. In such a case, the dishwasher changes the water or extends the washing or rinsing number by at least one time. 
     Meanwhile, the water having passed through the sensor assembly  700  arrives at a first drain  554  provided to an end of the bypass  556 . The first drain  554  is connected to a second drain  513  provided to the lower piece  510 , and extends to the drain chamber  900  of the sump housing  100  from the lower piece  510 . Namely, the drain chamber  900  always communicates with the guide assembly, and more particularly, with the bypass  556 . Hence, a portion of the water is passed through the bypass  556 , the sensor assembly  700 , and the first and second drains  554  and  513  to be introduced into the drain chamber  900 . 
     The drain chamber  900 , as explained in the foregoing description, is provided within the sump housing  100 . The drain chamber  900 , as shown in  FIG. 3 , includes a housing  910  forming a predetermined inner space. The housing  910  includes a first opening  911  communicating with the recess  110  and a second opening  912  communicating with the drain pump  400 . And, the housing  910  further includes an open top to communicate with the guide assembly  500  via the open top. Specifically, the first to third drains  554 ,  513 , and  511 , as shown in  FIG. 2 ,  FIG. 4A , and  FIG. 4B , are connected to a top portion of the housing  910  to enable the communication between the guide assembly  500  and the drain chamber  900 . The first and second drains  554  and  513  guide the water within the guide assembly  500  to the drain chamber  900 , and the third drain  511  guides the water within the drain chamber  900  to the guide assembly  500 . To support the first to third drains  554 ,  513 , and  511 , a rib  913  is provided in the housing  910 . In the present invention, the drain chamber  900  is configured to preliminarily filter the garbage or contaminant from the water while the dishes are washed. And, the drain chamber  900  serves as a path for draining the water in discharging the used water from the dishwasher. To effectively achieve the functions, the drain chamber  900  includes a valve  920  configured to allow the drain chamber  900  communicating with the guide assembly  500  to selectively communicate with the sump housing  100 , and more particularly, with the recess  110 . 
     The valve  920  substantially opens or closes the first opening  911  communicating with the recess  100  selectively. Specifically, the valve  920  includes a valve body  921  opening/closing the first opening  911  and a fixing portion  922  fixing the valve body  921  to the housing  910 . Preferably, the valve body  921  has a protrusion  923  tightly fitted in the first opening  911  to enable a stable opening/closing of the first opening  911 . The fixing portion  922 , as shown in  FIG. 3 , is fitted in a recess  914  provided to the rib  913  to be stably supported therein. The valve  920  is actuated by the pressure of the water flowing within the drain chamber  900  to play a role as a check valve allowing a unidirectional flow of the water. Namely, the valve  920  opens the first opening  911  by the pressure of the water only if the water starts flowing to the drain chamber  900  from the recess  110 , whereby the drain chamber  900  and the recess  110  come into communicating with each other. The valve  920  may be formed of an elastic material. In such a case, the valve  920  is elastically transformed by the pressure of the water to open the first opening  911 . And, the fixing portion  922  can be configured with a hinge. In such a case, the valve  920  revolves centering on the fixing portion  922  to open the first opening  911 . 
     Referring to  FIG. 4B , the drain pump  400  is working while the water is drained, whereby the water within the recess  110  starts flowing to the drain chamber  900 . The valve  920  opens the first opening  911  by the pressure of the flowing water to allow the drain chamber  900  to communicate with the sump housing  100 , i.e., the recess  110 . Hence, the drain chamber  900  communicates with the recess  110  as well as the guide assembly  500  while the water is discharged outside the dishwasher. Consequently, the drain pump  400  can discharge the water within the sump assembly, i.e., the guide assembly  500  and the recess  110 , from the dishwasher via the drain chamber  900 . 
     Alternatively, referring to  FIG. 4A , while the dishes are washed, the water keeps being drained into the drain chamber  900  via the first and second drains  554  and  513  from the guide assembly  500 . By the pressure of the drained water, the valve  920  closes the first opening  911 . The valve  920  isolates the drain chamber  900  from the sump housing  100 , i.e., the recess  110 , whereby the drain chamber  900  communicates with the guide assembly  500  only via the first to third drains  554 ,  513 , and  511  while the dishes are washed. Hence, the independent passage makes the water return to the guide assembly  900  via the drain chamber  900 . Namely, the water is not discharged from the dishwasher via the drain hose  80  and is not introduced into the recess  110  as well. 
     Moreover, the drain chamber  900  is situated below the guide assembly  500 . Hence, the water downwardly flows toward the drain chamber  900  from the guide assembly  500  via the first and second drains  554  and  513 . Thereafter, the water upwardly flows toward the guide assembly from the drain chamber  900 . For theses reasons, the garbage or contaminant involved in the water is deposited on a bottom of the drain chamber  900  due to its specific weight while the water passes through the drain chamber  900 . Specifically, the garbage or contaminant having a relatively heavy weight, i.e., high specific weight, is deposited on the bottom of the drain chamber  900 . Consequently, the drain chamber  900  plays a role in primarily filtering the garbage or contaminant from the washer while the dishes are washed. 
     Hence, the water drained from the drain chamber  900  ascends along the third drain  511  to return to the soil chamber  515 , as shown in  FIG. 2 , within the guide assembly  500 . As mentioned in the above explanation, the heavy garbage or contaminant included in the water is deposited on the bottom of the drain chamber  900  due to its weight but the light garbage and water are introduced into the soil chamber  515  only. The soil chamber  515 , as shown in  FIG. 2 , is provided to the lower piece  510  to enclose the impeller housing of the water supply pump  300 . The soil chamber  515  receives to store the water passed through the bypass  556  and the drain chamber  900  after the water has been pumped by the water supply pump  300 . If the water keeps flowing in the soil chamber  515 , a water level of the soil chamber  515  rises and the water finally floods out of the soil chamber  515 . 
     Meanwhile, the cover  600  covers the water guide assembly  500  and the sump housing  100 . For instance, the cover  600  has a disc shape. A multitude of openings are provided to its central part. And, a mesh type filter  610 , as shown in  FIG. 2 , is provided to each of the openings. In this case, the openings and the filters  610  are arranged over the soil chamber  515 . Hence, the water flooding from the soil chamber  515  passes through the filters  610  to be filtered and the contaminant or garbage failing to pass through the filter  610  remains in the soil chamber  515 . Thus, the drain chamber  900  primarily filters the heavy garbage or contaminant from the water, whereas the soil chamber  515  secondarily filters the relatively light garbage or contaminant from the water. Hence, the water can be almost completely purified by filtering the garbage or contaminant while the dishes are washed. Even if the water is repeatedly used, the washing efficiency reduction or the blocking of the passage of the sump assembly is prevented. Moreover, due to the drain chamber  900 , the soil chamber  515  just filters a small quantity of the garbage or contaminant that is relatively light, whereby the blocking or transformation of the filters  610  can be prevented. 
     A multitude of apertures  620  are provided to an edge area of the cover  600 . The apertures  620  guide the falling water used in washing the dishes in the tub  20  of the dishwasher and the flooding water passed through the filter  610  from the soil chamber  515  to the sump housing  100 . The water guided to the sump housing  100  is stored in the recess  110  at the center of the sump housing  100  together. 
     A first nipple  640  at a center of the cover  600  and a second nipple  630  at an edge of the cover  600 , as shown in  FIG. 2 , are provided to a top surface of the cover  600 . The first nipple  640  communicates with the first guide passage  557  of the water guide assembly  500  and the second nipple communicates with the second guide passages  555  of the water guide assembly  500 . The second connecting pipe  65  connected to the lower arm  45  is connected to the first nipple  640 , and the first connecting pipe  61  connected to the upper arm  41  is connected to the second nipple  630 . Hence, the water introduced into the first guide passage  557  is supplied to the lower arm  45  via the first nipple  640  and the second connecting pipe  65 . And, the water introduced into the second guide passage  555  is supplied to the lower arm  45  via the second nipple  630  and the first connecting pipe  61 . 
     An operation of the above-configured sump assembly  50  according to the present invention is explained as follows. 
     First of all, once the dishwasher initiates a cycle or process of washing or rinsing dishes, clean water is introduced into the recess  110  of the sump housing  100  via the water supply hole  120  connected to the water supply pipe  70 . The water introduced into the recess  110  is then heated by the heater  210 , if necessary. If a corresponding water supply is completed, the motor  310  of the water supply pump  300  is driven so that the water stored in the recess  110  can be pumped by the impeller  320  to enter the guide assembly  500 . 
     A portion of the pumped water flows in the valve receiving portion  553  via the outlet  551  and is then led to the first or second guide passage  557  or  555  by the diverting valve  810 . The water led to the first guide passage  557  is supplied to the lower arm  45 , while the other water led to the second guide passage  555  is supplied to the upper arm  41 . The water supplied to the lower arm  45  washes the dishes put on the lower rack  35  and the water supplied the upper arm  41  washes the dishes put on the upper rack  31 . Besides, the diverting valve  810  can connect both of the first and second guide passages  557  and  555  to the outlet  551  simultaneously. In such a case, the dishes on the upper and lower racks  31  and  35  can be washed by the water sprayed from the upper and lower arms  41  and  45 , respectively. 
     The water used in washing the dishes in the tub  20  and the garbage or soil detached from the dishes fall down to the bottom of the tub  20 . The falling garbage and water are re-introduced into the sump housing  100  via the apertures  620  provided to a circumference of the cover  600  to be re-stored in the recess  110 . As mentioned in the foregoing description, the water fed back to the sump housing  110  contains a considerable quantity of contaminant or garbage. The garbage is finely grinded by the disposer  150  situated between the impeller  320  and the bottom of the recess  110  of the sump housing  100 . And, the finely grinded garbage is pumped by the pump  300  to enter the guide assembly  500  together with the water. 
     Meanwhile, the rest of the water pumped by the impeller  320  of the pump is always introduced into the bypass  556 . The water introduced into the bypass  556  passes through the channel  710  of the sensor assembly  700  that accurately measures the pollution degree of the water flowing in the channel  710 . Hence, the dishwasher automatically adjusts the washing time, the washing number, the rinsing time, the rinsing number, etc. based on the pollution degree of the water sensed by the sensor assembly  700 . 
     The water having passed through the sensor assembly  700  is introduced into the drain chamber  900  via the first and second drains  554  and  513 . In doing so, since the drain pump  400  is not working, the water in the drain chamber  900  is not discharged from the drain chamber  900  but is directly introduced into the soil chamber  515  via the third drain  511 . In ding so, heavy garbage included in the water introduced into the drain chamber  900  is deposited at the bottom of the drain chamber  900  due to its weight but the light garbage ascends along the third drain  511  to be introduced into the soil chamber  515 . 
     The garbage and water introduced into the soil chamber  515  are stored therein. As time passes, the water level of the soil chamber  515  rises and the water finally floods out of the soil chamber  515 . The flooding water is passed through the filter  610  and the apertures  620  of the sump housing  100  in turn to be re-introduced into the sump housing  100 . Yet, the garbage introduced into the soil chamber  515  fails to pass through the filter  610  to be accumulated within the soil chamber  515 . 
     As mentioned in the foregoing description, a prescribed quantity of the pumped water is passed through the bypass  556  to be purified by the filter  610  step by step and is then re-supplied to the sump housing  100 . In doing so, it may seem that the soil chamber  515  and the filters  610  filter a small quantity of the water only. Yet, since they keep filtering the water across the washing or rinsing cycle overall, excellent water-filtering performance is achieved. 
     Meanwhile, if the washing or rinsing cycle is completed or if the water is badly polluted, the drain pump  400  is actuated. If so, the water and garbage stored in the soil chamber  515 , the drain chamber  900 , and the recess  110  of the sump housing  100  are discharged from the dishwasher by the drain pump  400  via the drain hose  80 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. 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.