Patent Publication Number: US-10779703-B2

Title: Rotating drum filter for a dishwashing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 12/910,203, filed Oct. 22, 2010, which is a continuation-in-part of U.S. application Ser. No. 12/643,394, filed Dec. 21, 2009, now U.S. Pat. No. 8,746,261, both of which are incorporated by reference herein in their entirety. Further, the present application is related to U.S. application Ser. No. 14/731,481, now U.S. Pat. No. 9,687,135; U.S. application Ser. No. 14/268,282, filed May 2, 2014; U.S. application Ser. No. 14/155,402, now U.S. Pat. No. 9,211,047; U.S. application Ser. No. 13,855,770, now U.S. Pat. No. 9,364,131; U.S. application Ser. No. 13/163,945, now U.S. Pat. No. 8,627,832; and U.S. application Ser. No. 12/966,420, now U.S. Pat. No. 8,667,974. 
    
    
     BACKGROUND 
     A dishwashing machine is a domestic appliance into which dishes and other cooking and eating wares (e.g., plates, bowls, glasses, flatware, pots, pans, bowls, etc.) are placed to be washed. A dishwashing machine includes various filters to separate soil particles from wash fluid. 
     BRIEF DESCRIPTION 
     An aspect of the disclosure relates to a dishwasher including a tub having a bottom wall, the tub at least partially defining a washing chamber configured for receiving dishes and having a tub liquid outlet, a spray assembly configured to spray liquid into the washing chamber, a filter assembly located outside the tub and including a housing defining a chamber and having a housing inlet fluidly coupled to the tub liquid outlet and a housing outlet fluidly coupled to the spray assembly, a rotatable filter fluidly disposed within the chamber between the housing inlet and the housing outlet, and an impeller rotatably mounted within the chamber and wherein liquid in the tub is recirculated by actuating the impeller such that the liquid is drawn into the chamber through the housing inlet, passes through the rotatable filter, and is expelled by the rotating impeller through the outlet to the tub and a conduit coupling the tub liquid outlet with the housing inlet and wherein the conduit includes a decreasing cross-sectional area in the direction of the housing inlet and is configured to reduce air entrainment during operation 
     An aspect of the disclosure relates to a dishwasher including a tub at least partially defining a washing chamber configured for receiving dishes and having a tub liquid outlet, a sump having a housing defining a chamber with a housing inlet and a housing outlet fluidly coupled to the tub, a rotatable filter fluidly disposed within the chamber between the housing inlet and the housing outlet wherein the filter fluidly divides the chamber into a first part that contains filtered soil particles and a second part that excludes filtered soil particles, a recirculation pump fluidly coupled between the chamber and the tub, a conduit coupling the tub liquid outlet with the housing inlet and wherein the conduit includes at least one of a decreasing cross-sectional area along at least a portion of a length of the conduit in the direction of the housing inlet or in a direction from the tub to the housing inlet, at least a portion of the conduit slopes downwardly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective view of a dishwashing machine. 
         FIG. 2  is a fragmentary perspective view of the tub of the dishwashing machine of  FIG. 1 . 
         FIG. 3  is a perspective view of an embodiment of a pump and filter assembly for the dishwashing machine of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the pump and filter assembly of  FIG. 3  taken along the line  4 - 4  shown in  FIG. 3 . 
         FIG. 5  is a cross-sectional view of the pump and filter assembly of  FIG. 3  taken along the line  5 - 5  shown in  FIG. 4  showing the rotary filter with two flow diverters. 
         FIG. 6  is a cross-sectional view of the pump and filter assembly of  FIG. 3  taken along the line  6 - 6  shown in  FIG. 3  showing a second embodiment of the rotary filter with a single flow diverter. 
         FIG. 7  is a cross-sectional elevation view of the pump and filter assembly of  FIG. 3  similar to  FIG. 5  and illustrating a third embodiment of the rotary filter with two flow diverters. 
         FIG. 8  is a cross-sectional view of a pump and filter assembly similar to  FIG. 4  and illustrating a fourth embodiment of the invention. 
         FIGS. 9A-9C  illustrate a pump and filter assembly having a bayonet mount assembly according to a fifth embodiment of the invention. 
         FIGS. 10A-10B  illustrate a pump and filter assembly having a reduction gear assembly according to a sixth embodiment of the invention. 
         FIG. 11A  is a perspective view of the sump, spray arm assembly, and pump assembly according to a seventh embodiment and removed from the dishwashing machine of  FIG. 1  for clarity. 
         FIG. 11B  is a cross-sectional view of an end of the pump assembly illustrated in  FIG. 11A . 
         FIG. 11C  is a cross-sectional view of the conduit illustrated in  FIG. 11A . 
         FIG. 11D  is a perspective view of the conduit illustrated in  FIG. 11A . 
     
    
    
     DETAILED DESCRIPTION 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     Referring to  FIG. 1 , a dishwashing machine  10  (hereinafter dishwasher  10 ) is shown. The dishwasher  10  has a tub  12  that defines a washing chamber  14  into which a user may place dishes and other cooking and eating wares (e.g., plates, bowls, glasses, flatware, pots, pans, bowls, etc.) to be washed. The dishwasher  10  includes a number of racks  16  located in the tub  12 . An upper dish rack  16  is shown in  FIG. 1 , although a lower dish rack is also included in the dishwasher  10 . A number of roller assemblies  18  are positioned between the dish racks  16  and the tub  12 . The roller assemblies  18  allow the dish racks  16  to extend from and retract into the tub  12 , which facilitates the loading and unloading of the dish racks  16 . The roller assemblies  18  include a number of rollers  20  that move along a corresponding support rail  22 . 
     A door  24  is hinged to the lower front edge of the tub  12 . The door  24  permits user access to the tub  12  to load and unload the dishwasher  10 . The door  24  also seals the front of the dishwasher  10  during a wash cycle. A control panel  26  is located at the top of the door  24 . The control panel  26  includes a number of controls  28 , such as buttons and knobs, which are used by a controller (not shown) to control the operation of the dishwasher  10 . A handle  30  is also included in the control panel  26 . The user may use the handle  30  to unlatch and open the door  24  to access the tub  12 . 
     A machine compartment  32  is located below the tub  12 . The machine compartment  32  is sealed from the tub  12 . In other words, unlike the tub  12 , which is filled with fluid and exposed to spray during the wash cycle, the machine compartment  32  does not fill with fluid and is not exposed to spray during the operation of the dishwasher  10 . Referring now to  FIG. 2 , the machine compartment  32  houses a recirculation pump assembly  34  and the drain pump  36 , as well as the dishwasher&#39;s other motor(s) and valve(s), along with the associated wiring and plumbing. 
     Referring now to  FIG. 2 , the tub  12  of the dishwasher  10  is shown in greater detail. The tub  12  includes a number of side walls  40  extending upwardly from a bottom wall  42  to define the washing chamber  14 . The open front side  44  of the tub  12  defines an access opening  46  of the dishwasher  10 . The access opening  46  provides the user with access to the dish racks  16  positioned in the washing chamber  14  when the door  24  is open. When closed, the door  24  seals the access opening  46 , which prevents the user from accessing the dish racks  16 . The door  24  also prevents fluid from escaping through the access opening  46  of the dishwasher  10  during a wash cycle. 
     The bottom wall  42  of the tub  12  has a sump  50  positioned therein. At the start of a wash cycle, fluid enters the tub  12  through a hole  48  defined in the side wall  40 . The sloped configuration of the bottom wall  42  directs fluid into the sump  50 . The recirculation pump assembly  34  removes such water and/or wash chemistry from the sump  50  through a hole  52  defined the bottom of the sump  50  after the sump  50  is partially filled with fluid. 
     The recirculation pump assembly  34  is fluidly coupled to a rotating spray arm  54  that sprays water and/or wash chemistry onto the dish racks  16  (and hence any wares positioned thereon). Additional rotating spray arms (not shown) are positioned above the spray arm  54 . It should also be appreciated that the dishwashing machine  10  may include other spray arms positioned at various locations in the tub  12 . As shown in  FIG. 2 , the spray arm  54  has a number of nozzles  56 . Fluid passes from the recirculation pump assembly  34  into the spray arm  54  and then exits the spray arm  54  through the nozzles  56 . In the illustrative embodiment described herein, the nozzles  56  are embodied simply as holes formed in the spray arm  54 . However, it is within the scope of the disclosure for the nozzles  56  to include inserts such as tips or other similar structures that are placed into the holes formed in the spray arm  54 . Such inserts may be useful in configuring the spray direction or spray pattern of the fluid expelled from the spray arm  54 . 
     After wash fluid contacts the dish racks  16  and any wares positioned in the washing chamber  14 , a mixture of fluid and soil falls onto the bottom wall  42  and collects in the sump  50 . The recirculation pump assembly  34  draws the mixture out of the sump  50  through the hole  52 . As will be discussed in detail below, fluid is filtered in the recirculation pump assembly  34  and re-circulated onto the dish racks  16 . At the conclusion of the wash cycle, the drain pump  36  removes both wash fluid and soil particles from the sump  50  and the tub  12 . 
     Referring now to  FIG. 3 , the recirculation pump assembly  34  is shown removed from the dishwasher  10 . The recirculation pump assembly  34  includes a wash pump  60  that is secured to a housing  62 . The housing  62  includes cylindrical filter casing  64  positioned between a manifold  68  and the wash pump  60 . The manifold  68  has an inlet port  70 , which is fluidly coupled to the hole  52  defined in the sump  50 , and an outlet port  72 , which is fluidly coupled to the drain pump  36 . Another outlet port  74  extends upwardly from the wash pump  60  and is fluidly coupled to the rotating spray arm  54 . While recirculation pump assembly  34  is included in the dishwasher  10 , it will be appreciated that in other embodiments, the recirculation pump assembly  34  may be a device separate from the dishwasher  10 . For example, the recirculation pump assembly  34  might be positioned in a cabinet adjacent to the dishwasher  10 . In such embodiments, a number of fluid hoses may be used to connect the recirculation pump assembly  34  to the dishwasher  10 . 
     Referring now to  FIG. 4 , a cross-sectional view of the recirculation pump assembly  34  is shown. The filter casing  64  is a hollow cylinder having a side wall  76  that extends from an end  78  secured to the manifold  68  to an opposite end  80  secured to the wash pump  60 . The side wall  76  defines a filter chamber  82  that extends the length of the filter casing  64 . 
     The side wall  76  has an inner surface  84  facing the filter chamber  82 . A number of rectangular ribs  85  extend from the inner surface  84  into the filter chamber  82 . The ribs  85  are configured to create drag to counteract the movement of fluid within the filter chamber  82 . It should be appreciated that in other embodiments, each of the ribs  85  may take the form of a wedge, cylinder, pyramid, or other shape configured to create drag to counteract the movement of fluid within the filter chamber  82 . 
     The manifold  68  has a main body  86  that is secured to the end  78  of the filter casing  64 . The inlet port  70  extends upwardly from the main body  86  and is configured to be coupled to a fluid hose (not shown) extending from the hole  52  defined in the sump  50 . The inlet port  70  opens through a sidewall  87  of the main body  86  into the filter chamber  82  of the filter casing  64 . As such, during the wash cycle, a mixture of fluid and soil particles advances from the sump  50  into the filter chamber  82  and fills the filter chamber  82 . As shown in  FIG. 4 , the inlet port  70  has a filter screen  88  positioned at an upper end  90 . The filter screen  88  has a plurality of holes  91  extending there through. Each of the holes  91  is sized such that large soil particles are prevented from advancing into the filter chamber  82 . 
     A passageway (not shown) places the outlet port  72  of the manifold  68  in fluid communication with the filter chamber  82 . When the drain pump  36  is energized, fluid and soil particles from the sump  50  pass downwardly through the inlet port  70  into the filter chamber  82 . Fluid then advances from the filter chamber  82  through the passageway and out the outlet port  72 . 
     The wash pump  60  is secured at the opposite end  80  of the filter casing  64 . The wash pump  60  includes a motor  92  (see  FIG. 3 ) secured to a cylindrical pump housing  94 . The pump housing  94  includes a side wall  96  extending from a base wall  98  to an end wall  100 . The base wall  98  is secured to the motor  92  while the end wall  100  is secured to the end  80  of the filter casing  64 . The walls  96 ,  98 ,  100  define an impeller chamber  102  that fills with fluid during the wash cycle. As shown in  FIG. 4 , the outlet port  74  is coupled to the side wall  96  of the pump housing  94  and opens into the chamber  102 . The outlet port  74  is configured to receive a fluid hose (not shown) such that the outlet port  74  may be fluidly coupled to the spray arm  54 . 
     The wash pump  60  also includes an impeller  104 . The impeller  104  has a shell  106  that extends from a back end  108  to a front end  110 . The back end  108  of the shell  106  is positioned in the chamber  102  and has a bore  112  formed therein. A drive shaft  114 , which is rotatably coupled to the motor  92 , is received in the bore  112 . The motor  92  acts on the drive shaft  114  to rotate the impeller  104  about an imaginary axis  116  in the direction indicated by arrow  118  (see  FIG. 5 ). The motor  92  is connected to a power supply (not shown), which provides the electric current necessary for the motor  92  to spin the drive shaft  114  and rotate the impeller  104 . In the illustrative embodiment, the motor  92  is configured to rotate the impeller  104  about the axis  116  at 3200 rpm. 
     The front end  110  of the impeller shell  106  is positioned in the filter chamber  82  of the filter casing  64  and has an inlet opening  120  formed in the center thereof. The shell  106  has a number of vanes  122  that extend away from the inlet opening  120  to an outer edge  124  of the shell  106 . The rotation of the impeller  104  about the axis  116  draws fluid from the filter chamber  82  of the filter casing  64  into the inlet opening  120 . The fluid is then forced by the rotation of the impeller  104  outward along the vanes  122 . Fluid exiting the impeller  104  is advanced out of the chamber  102  through the outlet port  74  to the spray arm  54 . 
     As shown in  FIG. 4 , the front end  110  of the impeller shell  106  is coupled to a rotary filter  130  positioned in the filter chamber  82  of the filter casing  64 . The filter  130  has a cylindrical filter drum  132  extending from an end  134  secured to the impeller shell  106  to an end  136  rotatably coupled to a bearing  138 , which is secured the main body  86  of the manifold  68 . As such, the filter  130  is operable to rotate about the axis  116  with the impeller  104 . 
     A filter sheet  140  extends from one end  134  to the other end  136  of the filter drum  132  and encloses a hollow interior  142 . The sheet  140  includes a number of holes  144 , and each hole  144  extends from an outer surface  146  of the sheet  140  to an inner surface  148 . In the illustrative embodiment, the sheet  140  is a sheet of chemically etched metal. Each hole  144  is sized to allow for the passage of wash fluid into the hollow interior  142  and prevent the passage of soil particles. 
     As such, the filter sheet  140  divides the filter chamber  82  into two parts. As wash fluid and removed soil particles enter the filter chamber  82  through the inlet port  70 , a mixture  150  of fluid and soil particles is collected in the filter chamber  82  in a region  152  external to the filter sheet  140 . Because the holes  144  permit fluid to pass into the hollow interior  142 , a volume of filtered fluid  156  is formed in the hollow interior  142 . 
     Referring now to  FIGS. 4 and 5 , a flow diverter  160  is positioned in the hollow interior  142  of the filter  130 . The diverter  160  has a body  166  that is positioned adjacent to the inner surface  148  of the sheet  140 . The body  166  has an outer surface  168  that defines a circular arc  170  having a radius smaller than the radius of the sheet  140 . A number of arms  172  extend away from the body  166  and secure the diverter  160  to a beam  174  positioned in the center of the filter  130 . As best seen in  FIG. 4 , the beam  174  is coupled at an end  176  to the side wall  87  of the manifold  68 . In this way, the beam  174  secures the body  166  to the housing  62 . 
     Another flow diverter  180  is positioned between the outer surface  146  of the sheet  140  and the inner surface  84  of the housing  62 . The diverter  180  has a fin-shaped body  182  that extends from a leading edge  184  to a trailing end  186 . As shown in  FIG. 4 , the body  182  extends along the length of the filter drum  132  from one end  134  to the other end  136 . It will be appreciated that in other embodiments, the diverter  180  may take other forms, such as, for example, having an inner surface that defines a circular arc having a radius larger than the radius of the sheet  140 . As shown in  FIG. 5 , the body  182  is secured to a beam  184 . The beam  187  extends from the side wall  87  of the manifold  68 . In this way, the beam  187  secures the body  182  to the housing  62 . 
     As shown in  FIG. 5 , the diverter  180  is positioned opposite the diverter  160  on the same side of the filter chamber  82 . The diverter  160  is spaced apart from the diverter  180  so as to create a gap  188  therebetween. The sheet  140  is positioned within the gap  188 . 
     In operation, wash fluid, such as water and/or wash chemistry (i.e., water and/or detergents, enzymes, surfactants, and other cleaning or conditioning chemistry), enters the tub  12  through the hole  48  defined in the side wall  40  and flows into the sump  50  and down the hole  52  defined therein. As the filter chamber  82  fills, wash fluid passes through the holes  144  extending through the filter sheet  140  into the hollow interior  142 . After the filter chamber  82  is completely filled and the sump  50  is partially filled with wash fluid, the dishwasher  10  activates the motor  92 . 
     Activation of the motor  92  causes the impeller  104  and the filter  130  to rotate. The rotation of the impeller  104  draws wash fluid from the filter chamber  82  through the filter sheet  140  and into the inlet opening  120  of the impeller shell  106 . Fluid then advances outward along the vanes  122  of the impeller shell  106  and out of the chamber  102  through the outlet port  74  to the spray arm  54 . When wash fluid is delivered to the spray arm  54 , it is expelled from the spray arm  54  onto any dishes or other wares positioned in the washing chamber  14 . Wash fluid removes soil particles located on the dishwares, and the mixture of wash fluid and soil particles falls onto the bottom wall  42  of the tub  12 . The sloped configuration of the bottom wall  42  directs that mixture into the sump  50  and down the hole  52  defined in the sump  50 . 
     While fluid is permitted to pass through the sheet  140 , the size of the holes  144  prevents the soil particles of the mixture  152  from moving into the hollow interior  142 . As a result, those soil particles accumulate on the outer surface  146  of the sheet  140  and cover the holes  144 , thereby preventing fluid from passing into the hollow interior  142 . 
     The rotation of the filter  130  about the axis  116  causes the mixture  150  of fluid and soil particles within the filter chamber  82  to rotate about the axis  116  in the direction indicated by the arrow  118 . Centrifugal force urges the soil particles toward the side wall  76  as the mixture  150  rotates about the axis  116 . The diverters  160 ,  180  divide the mixture  150  into a first portion  190 , which advances through the gap  188 , and a second portion  192 , which bypasses the gap  188 . As the portion  190  advances through the gap  188 , the angular velocity of the portion  190  increases relative to its previous velocity as well as relative to the second portion  192 . The increase in angular velocity results in a low pressure region between the diverters  160 ,  180 . In that low pressure region, accumulated soil particles are lifted from the sheet  140 , thereby, cleaning the sheet  140  and permitting the passage of fluid through the holes  144  into the hollow interior  142 . Additionally, the acceleration accompanying the increase in angular velocity as the portion  190  enters the gap  188  provides additional force to lift the accumulated soil particles from the sheet  140 . 
     Referring now to  FIG. 6 , a cross-section of a second embodiment of the rotary filter  130  with a single flow diverter  200 . The diverter  200 , like the diverter  180  of the embodiment of  FIGS. 1-5 , is positioned within the filter chamber  82  external of the hollow interior  142 . The diverter  200  is secured to the side wall  87  of the manifold  68  via a beam  202 . The diverter  200  has a fin-shaped body  204  that extends from a tip  206  to a trailing end  208 . The tip  206  has a leading edge  210  that is positioned proximate to the outer surface  146  of the sheet  140 , and the tip  206  and the outer surface  146  of the sheet  140  define a gap  212  there between. 
     In operation, the rotation of the filter  130  about the axis  116  causes the mixture  150  of fluid and soil particles to rotate about the axis  116  in the direction indicated by the arrow  118 . The diverter  200  divides the mixture  150  into a first portion  290 , which passes through the gap  212  defined between the diverter  200  and the sheet  140 , and a second portion  292 , which bypasses the gap  212 . As the first portion  290  passes through the gap  212 , the angular velocity of the first portion  290  of the mixture  150  increases relative to the second portion  292 . The increase in angular velocity results in low pressure in the gap  212  between the diverter  200  and the outer surface  146  of the sheet  140 . In that low pressure region, accumulated soil particles are lifted from the sheet  140  by the first portion  290  of the fluid, thereby cleaning the sheet  140  and permitting the passage of fluid through the holes  144  into the hollow interior  142 . In some embodiments, the gap  212  is sized such that the angular velocity of the first portion  290  is at least sixteen percent greater than the angular velocity of the second portion  292  of the fluid. 
       FIG. 7  illustrates a third embodiment of the rotary filter  330  with two flow diverters  360  and  380 . The third embodiment is similar to the first embodiment having two flow diverters  160  and  180  as illustrated in  FIGS. 1-5 . Therefore, like parts will be identified with like numerals increased by 200, with it being understood that the description of the like parts of the first embodiment applies to the third embodiment, unless otherwise noted. 
     One difference between the first embodiment and the third embodiment is that the flow diverter  360  has a body  366  with an outer surface  368  that is less symmetrical than that of the first embodiment  360 . More specifically, the body  366  is shaped in such a manner that a leading gap  393  is formed when the body  366  is positioned adjacent to the inner surface  348  of the sheet  340 . A trailing gap  394 , which is smaller than the leading gap  393 , is also formed when the body  366  is positioned adjacent to the inner surface  348  of the sheet  340 . 
     The third embodiment operates much the same way as the first embodiment. That is, the rotation of the filter  330  about the axis  316  causes the mixture  350  of fluid and soil particles to rotate about the axis  316  in the direction indicated by the arrow  318 . The diverters  360 ,  380  divide the mixture  350  into a first portion  390 , which advances through the gap  388 , and a second portion  392 , which bypasses the gap  388 . The orientation of the body  366  such that it has a larger leading gap  393  that reduces to a smaller trailing gap  394  results in a decreasing cross-sectional area between the outer surface  368  of the body  366  and the inner surface  348  of the filter sheet  340  along the direction of fluid flow between the body  366  and the filter sheet  340 , which creates a wedge action that forces water from the hollow interior  342  through a number of holes  344  to the outer surface  346  of the sheet  340 . Thus, a backflow is induced by the leading gap  393 . The backwash of water against accumulated soil particles on the sheet  340  better cleans the sheet  340 . 
       FIG. 8  illustrates a fourth embodiment of a pump assembly  434  and a rotary filter  540 . The fourth embodiment is similar to the first embodiment as illustrated in  FIGS. 1-5 . Therefore, like parts will be identified with like numerals increased by 400, with it being understood that the description of the like parts of the first embodiment applies to the fourth embodiment, unless otherwise noted. 
     One difference between the first embodiment and the fourth embodiment is that the front end  510  of the impeller shell  506  and the one end  534  of the rotary filter  530  are a singular piece  571 . Such a singular piece  571  may be formed through injection molding. With the impeller shell  506  and the one end  534  of the rotary filter  530  being a singular piece  570  it will be appreciated that the movement of the impeller  504  causes the filter  530  to rotate and that the filter  530  rotates at the same speed about the axis  516  as the impeller  504 . 
       FIGS. 9A-9C  illustrate a fifth embodiment of a pump assembly  634  and a rotary filter  740 . The fifth embodiment is similar to the first embodiment as illustrated in  FIGS. 1-5 . Therefore, like parts will be identified with like numerals increased by 600, with it being understood that the description of the like parts of the first embodiment applies to the fifth embodiment, unless otherwise noted. 
     One difference between the first embodiment and the fifth embodiment is that the impeller  704  and the rotary filter  730  are coupled together with a bayonet mount  773  as illustrated in  FIG. 9A . More specifically, the impeller shell  706  includes a male side  773   a  of the bayonet mount  773  and the rotary filter  730  includes a female side  773   b  of the bayonet mount  773 , which is shaped in a manner to receive the male side  773   a . The male side  773   a  includes a number of lugs  775  projecting from and spaced slightly from the front end  710  of the impeller shell  706 . The female side  773   b  includes a plate  777   a  extending radially inward from the end  734  of the rotary filter  730 . 
     Preferably, the female side  773   b  of the rotary filter  730  and male side  773   a  of the impeller  704  are fastened in the same direction as rotation of the impeller  704  and filter  730 . In this manner, the bayonet mount  773  will not unfasten during rotation of the impeller  704  and filter  730 . Alternatively, a locking mechanism or pin (not shown) may be inserted to hold the bayonet mount  773  in place during rotation of the impeller  704  and filter  730 . With the impeller shell  706  and the one end  734  of the rotary filter  730  being coupled together with the bayonet mount  773  it will be appreciated that the movement of the impeller  704  causes the filter  730  to rotate and that the filter  730  rotates at the same speed about the axis  716  as the impeller  704 . 
       FIG. 9B  illustrates the male side  773   a  of the bayonet mount  773 . As can be more clearly seen, the male side  773   a  includes a number of lugs  775  projecting from its front end  710 . Although three lugs  775  have been illustrated, it has been contemplated that alternative numbers of lugs  775  may be used. 
       FIG. 9C  illustrates more clearly the female side  773   b  of the bayonet mount  773 . The plate  777   a  is illustrated as having several slots  777   b  corresponding to the lugs  775  on the male side  773   a . The slots  777   b  of the female side  773   b  are slightly larger than the corresponding lugs  775  of the male side  773   a  such that the lugs  775  may fit into the appropriately sized slots  777   b . Once the lugs  775  are inserted into the slots  777   b  the rotary filter  730  may be fastened to the impeller  704  by turning it a small amount such that the lugs  775  are located behind the plate  777   a  ( FIG. 9A ). 
       FIGS. 10A and 10B  illustrate a sixth embodiment of a pump assembly  834  and a rotary filter  930 . The sixth embodiment is similar to the first embodiment as illustrated in  FIGS. 1-5 . Therefore, like parts will be identified with like numerals increased by 800, with it being understood that the description of the like parts of the first embodiment applies to the sixth embodiment, unless otherwise noted. 
     Referring to  FIG. 10A , one difference between the first embodiment and the sixth embodiment is that the impeller  904  and the rotary filter  930  are coupled together through a speed adjuster. As illustrated, the speed adjuster is a speed reducer illustrated as a drive assembly  981 . The drive assembly  981  is composed of the front end  910  of the impeller  904 , which acts as a drive shaft, a drive gear  983 , idler gears  985 , and a ring gear  987  having a support  989 . The drive gear  983 , idler gears  985 , and ring gear  987  all form the speed adjuster and may be selected such that they alter the rotational speed of the filter  930  from that of the impeller  904 . As the speed adjuster illustrated in  FIG. 10A  is a speed reducer the drive assembly  981  is assembled such that the filter  930  is rotated at a speed slower than the rotational speed of the impeller  904 . 
     The front end  910  is operably coupled to the drive gear  983 . The ring gear  987  may have a support  989  extending from it. The support  989  may be operably coupled to the end  934  of the rotary filter  930  such that movement of the ring gear  987  and the support  989  may be transferred to the rotary filter  930 . 
     Referring to  FIG. 10B , the drive gear  983  is enmeshed with the idler gears  985 , which are in turn enmeshed with an outer ring gear  987 . Thus, in operation, activation of the motor  892  causes the impeller  904  to rotate. The rotation of the impeller  904  in turn causes the drive gear  983  to rotate because the drive gear  983  is operably coupled to the impeller. As the drive gear  983  is rotated, the idler gears  985  are rotated and they in turn rotate the ring gear  987 , which causes the filter  930  to rotate as it is mounted to the support  989  on the ring gear  987 . 
     As the rotational speed of the impeller is relatively high (3000 rpm or higher), it is contemplated that the gear chain will form a gear reduction such that it forms a speed reducer and one rotation of the impeller  904  results in less than a full rotation of the rotary filter  930 . Although the gear assembly shown is an epicyclical gear assembly; it has been contemplated that other types of gear assemblies could be used. Further, the speed adjuster may also include a speed increaser operably coupling the filter  930  to the impeller  904  such that when the impeller  904  is rotated that filter  930  is rotated at a faster speed than the impeller  904 . For example, a swapping of the ring gear  987  and the drive gear  983  could provide a speed increaser, where the filter rotates faster than the impeller. 
       FIG. 11A  illustrates a sump  1050 , spray arm assembly  1054 , and pump assembly  1034  according to a seventh embodiment removed from the dishwashing machine for clarity. The seventh embodiment is similar to the first embodiment as illustrated in  FIGS. 1-5 . Therefore, like parts will be identified with like numerals increased by 1000, with it being understood that the description of the like parts of the first embodiment applies to the seventh embodiment, unless otherwise noted. 
     As can be seen in  FIG. 11A , a portion of the bottom wall  1042  of the tub  1012  has a sump  1050  positioned therein. An outlet  1052  defined in the sump  1050  leads to a conduit  1090 . The outlet  1052  is illustrated as a cup with an open top and bottom. A pump hood or grate  1095  is located in the outlet  1052  forming the inlet of the conduit  1090 . The conduit  1090  extends downwardly to an inlet port  1070  of the housing  1062  and thus fluidly couples the tub  1012  to the housing  1062 . A recirculation pump assembly  1034  having a wash pump  1060  is secured to the housing  1062 . 
     The grate  1095  has a plurality of openings  1096 , which are sized such that large debris particles such as utensils, toothpicks, screws, etc. are prevented from advancing into the conduit  1090 . The plurality of openings  1096  have a total cross-sectional area of about 1800 sq. mm and this provides an adequate flow rates to the wash pump  1060  that range from 25-50 liters per minute. The grate  1095  and its plurality of openings  1096  are sized and shaped so as to provide substantially non-turbulent liquid flow to the conduit  1090 . More specifically, the grate  1095  eliminates any vortexes which may otherwise be formed in the conduit  1090 . The grate  1095  creates a more laminar flow of liquid and decreases the turbulence of the liquid entering the conduit  1090 . In this manner, the grate  1095  allows air to escape the liquid and minimizes air entrainment in the liquid. This is important as air which is entrained in the liquid reduces the efficiency of the wash pump  1060 . 
       FIG. 11B  illustrates an interior cross-sectional view of the end of the pump assembly  1034  where the inlet port  1070  is located. The inlet port  1070  has been illustrated as having an oblong or kidney shape. The shape of the inlet port  1070  allows liquid to enter into the chamber created by the housing  1062  outside of the rotary filter  1130  positioned therein. This allows the filter  1130  to be fluidly disposed between the inlet port  1070  and the wash pump  1060 . 
     Referring now to  FIG. 11C , a sectional view of the conduit  1090  has been illustrated. This sectional view more clearly illustrates that the conduit  1090  from the tub  1012  to the inlet port  1070 , indicated as numeral  1090 B slopes downwardly. The downward slope from the tub  1012  to the inlet port  1070 , indicated as numeral  1090 B is approximately five degrees. The downward slope of the conduit  1090  is important as it aids in letting air escape from the housing  1062 . More specifically, as the housing  1062  is filled from bottom to top the gradual slope in the conduit  1090  helps to allow air to escape from the housing  1062  as the housing  1062  is being filled with liquid. 
     Further, as illustrated in  FIG. 11D , the conduit  1090  my have a gradually-decreasing cross-sectional area. This may be seen with reference to the three cross sections illustrated as  1090 C,  1090 D, and  1090 E. As illustrated, the cross-sectional area  1090 D located at a middle portion of the conduit  1090  is smaller than the cross-sectional area  1090 C at the inlet of the conduit  1090 . Further, the cross-sectional area  1090 E located at the end of the conduit  1090 , where it feeds into the inlet port  1070 , is smaller than the cross-sectional area  1090 D at the middle portion of the conduit  1090 . The gradual slope in the conduit  1090  and the gradually decreasing cross-sectional area cooperate to provide a slow acceleration of liquid through the conduit  1090 . The slow liquid acceleration through the conduit  1090  provides time for air to escape the liquid and minimizes or eliminates air entrainment in the liquid and increases the efficiency of the wash pump  1060 . It has also been contemplated that the conduit  1090  may maintain a consistent cross-sectional area through its entire length but that there may be a reduction in cross-sectional area from the outlet  1052  to the conduit  1090 . Such a reduction of cross-sectional area may occur through the length of the outlet  1052  and may be approximately a 40% decrease in cross-sectional area. 
     Referring back to  FIG. 11A , during the wash cycle, when liquid is being recirculated within the dishwasher  10  the sloped configuration of the bottom wall  1042  directs liquid into the sump  1050 . The recirculation pump assembly  1034  removes such liquid and/or wash chemistry from the sump  1050  through the outlet  1052  defined in the bottom of the sump  1050 . The grate  1095  acts to strain out large debris particles from the liquid before the liquid reaches the housing  1062 . A divider  1090 A has been illustrated as being located in the lower end of the conduit  1090  and aid in introducing the liquid into the housing  1062  in a direction that is either straight into the housing  1062  or in the same direction as the rotary filter  1130  is turning. The liquid may then be filtered by the rotary filter  1130  and re-circulated by the wash pump  1060  into the tub  1012 . 
     There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatuses, and system described herein. For example, the embodiments of the apparatus described above allow for cleaning of the filter throughout the life of the dishwasher and this maximizes the performance of the dishwasher. Thus, such embodiments require less user maintenance than required by typical dishwashers. Further, in the apparatuses described above the impeller and the filter are operably coupled such that no separate driver is needed to rotate the filter. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.