Patent Publication Number: US-10314457-B2

Title: Filter with artificial boundary for a dishwashing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/692,193, filed Aug. 31, 2017 which is a continuation of U.S. application Ser. No. 14/503,678, filed Oct. 1, 2014, now U.S. Pat. No. 9,861,251, which is a continuation-in-part of U.S. application Ser. No. 13/164,501, filed Jun. 20, 2011, now U.S. Pat. No. 9,010,344, issued Apr. 21, 2015, and entitled Rotating Filter for a Dishwashing Machine, all of which are incorporated by reference herein in their entirety. 
    
    
     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 liquid during the recirculation of the sprayed wash liquid. 
     BRIEF DESCRIPTION 
     An aspect of the present disclosure relates to a dishwasher including a tub at least partially defining a treating chamber, a liquid spraying system configured to supply at least one spray of liquid into the treating chamber, a liquid recirculation system fluidly coupling the treating chamber to the liquid spraying system and defining a recirculation flow path, a liquid filtering system, a housing defining an enclosed filter chamber and configured to be fluidly coupled to the recirculation flow path, a filter located within the housing and having a first end axially spaced from a second end, where the second end is larger in diameter than the first end, and defines a cone-shaped filter that encloses a hollow interior, the filter having a first surface and a second surface, the filter being positioned within the recirculation flow path to filter soils from liquid flowing through the recirculation flow path as the liquid passes through the filter from the first surface to the second surface and where the filter fluidly divides the filter chamber into a first part that contains filtered soil particles and a second part that excludes filtered soil particles, and a flow diverter spaced apart from one of the first surface or the second surface to define a gap through which at least some of the liquid passes as the liquid flows through the recirculation flow path. 
    
    
     
       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. 3 . 
         FIG. 6  is a schematic top view of a filter and artificial boundary illustrated in the pump and filter assembly of  FIG. 4 . 
         FIG. 7  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 3  according to a second embodiment. 
         FIG. 8  is an exploded view of a third embodiment of a pump and filter assembly, which may be used in the dishwashing machine of  FIG. 1 . 
         FIG. 9  is a cross-sectional view of the assembled pump and filter assembly of  FIG. 8 . 
         FIG. 10  is a schematic perspective view of a filter and artificial boundary illustrated in  FIG. 8 . 
         FIG. 11  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 8  according to a fourth embodiment. 
         FIG. 12  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 8  according to a fifth embodiment. 
         FIG. 13  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 3  according to a sixth embodiment. 
         FIG. 14  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 3  according to a seventh embodiment. 
         FIG. 15  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 8  according to an eighth embodiment. 
         FIG. 16  is a schematic top view of a filter and artificial boundary, which may be used in the pump and filter assembly of  FIG. 3  according to a ninth embodiment. 
     
    
    
     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 present disclosure as defined by the appended claims. For example, while the present invention is described in terms of a conventional dishwashing unit, it could also be implemented in other types of dishwashing units, such as in-sink dishwashers or drawer-type dishwashers. 
     Referring to  FIG. 1 , a dishwashing machine  10  (hereinafter dishwasher  10 ) is shown. The dishwasher  10  has a tub  12  that at least partially defines a treating 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 liquid and exposed to spray during the wash cycle, the machine compartment  32  does not fill with liquid 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. The recirculation pump  36  and associated wiring and plumbing form a liquid recirculation system. 
     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 treating 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 treating 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 liquid 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, liquid enters the tub  12  through a hole  48  defined in the side wall  40 . The sloped configuration of the bottom wall  42  directs liquid 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 in the bottom of the sump  50  after the sump  50  is partially filled with liquid. 
     The liquid recirculation system supplies liquid to a liquid spraying system, which includes a spray arm  54 , to recirculate the sprayed liquid in the tub  12 . 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) to effect a recirculation of the liquid from the treating chamber  14  to the liquid spraying system to define a recirculation flow path. 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 . Liquid 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 liquid expelled from the spray arm  54 . 
     After wash liquid contacts the dish racks  16 , and any wares positioned in the treating chamber  14 , a mixture of liquid 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, liquid 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 liquid 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 cylindrical filter casing  64  provides a liquid filtering system. 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 liquid 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 an interior or filter chamber  82  that extends the length of the filter casing  64 . The housing  62 , which defines the filter chamber  82 , may be physically remote from the tub  12  such that the filter chamber  82  may form a sump that is also remote from the tub  12 . 
     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 liquid 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 liquid 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 liquid 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 liquid 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, liquid and soil particles from the sump  50  pass downwardly through the inlet port  70  into the filter chamber  82 . Liquid 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 liquid 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 liquid 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 a counter-clockwise direction. In this case, the axis  116  is a central axis of the filter  130 . The central axis  116  may be oriented vertically or non-vertically and as illustrated, the central axis is oriented substantially horizontally. 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 liquid from the filter chamber  82  of the filter casing  64  into the inlet opening  120 . The liquid is then forced by the rotation of the impeller  104  outward along the vanes  122 . Liquid 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 a first end  134  secured to the impeller shell  106  to a second end  136 , which is axially spaced from the first end  134 , 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 . 
     The rotating filter  130  is located within the recirculation flow path and has an upstream surface  146  and a downstream surface  148  such that the recirculating liquid passes through the rotating filter  130  from the upstream surface  146  to the downstream surface  148  to effect a filtering of the liquid. In the described flow direction, the upstream surface  146  correlates to the outer surface and that the downstream surface  148  correlates to the inner surface. If the flow direction is reversed, the downstream surface may correlate with the outer surface and that the upstream surface may correlate with the inner surface. 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 passageways  144 , and each hole  144  extends from the upstream surface  146  to the downstream 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 liquid 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 liquid and removed soil particles enter the filter chamber  82  through the inlet port  70 , a mixture  150  of liquid and soil particles is collected in the filter chamber  82  in a region  152  external to the filter sheet  140 . Because the passageways  144  permit liquid to pass into the hollow interior  142 , a volume of filtered liquid  156  is formed in the hollow interior  142 . 
     A flow diverter or artificial boundary  160  is positioned in the hollow interior  142  of the filter  130 . The diverter  160  may be spaced from the downstream surface  148  of the sheet  140  to form a gap there between and may be secured by a beam  174  to the housing  62 . Suitable artificial flow boundaries are set forth in detail in U.S. patent application Ser. No. 12/966,420, filed Dec. 13, 2010, now U.S. Pat. No. 8,667,974, and titled “Rotating Filter for a Dishwashing Machine,” which is incorporated herein by reference in its entirety. 
     Another flow diverter or artificial boundary  180  is illustrated as being positioned between the upstream surface  146  of the sheet  140  and the inner surface  84  of the housing  62 . The diverter  180  has a body  182  that is spaced from at least a portion of the upstream surface  146  to form a gap  188  there between and an increased shear force zone  190  ( FIG. 5 ). The body  182  extends along the length of the filter  130  from one end  134  to the other end  136  and has a surface  183  oriented at an angle relative to the central axis  116 . The artificial boundary  180  may be positioned in a partially or completely radial overlapping relationship with the artificial boundary  160 . In some cases, the shear zone benefit may be created with the artificial boundaries being in proximity to each other and not radially overlapping to any extent. The artificial boundaries  160  and  180  may have complementary shapes or cross-sections, which act to enhance the shear force benefit. 
     It is contemplated that the artificial boundaries may be fixed relative to the filter, as illustrated, or that they may move relative to the filter. Suitable mechanisms for moving the artificial boundary  160  and/or the artificial boundary  180  are set forth in detail in U.S. patent application Ser. No. 13/108,026, filed May 16, 2011, now U.S. Pat. No. 9,107,559, and titled “Dishwasher with Filter Assembly,” which is incorporated herein by reference in its entirety. 
     In operation, wash liquid, 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 liquid passes through the passageways  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 liquid, 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 liquid from the filter chamber  82  through the filter sheet  140  and into the inlet opening  120  of the impeller shell  106 . Liquid 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 liquid is delivered to the spray arm  54 , it is expelled from the spray arm  54  onto any dishes or other wares positioned in the treating chamber  14 . Wash liquid removes soil particles located on the dishware, and the mixture of wash liquid 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 back to the filter chamber  82 . 
     While liquid is permitted to pass through the sheet  140 , the size of the passageways  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 upstream surface  146  of the sheet  140  and cover the passageways  144 , thereby preventing liquid from passing into the hollow interior  142 . 
     The rotation of the filter  130  about the axis  116  causes the unfiltered liquid or mixture  150  of liquid and soil particles within the filter chamber  82  to rotate about the axis  116  the same counter-clockwise direction. Centrifugal force urges the soil particles toward the side wall  76  as the mixture  150  rotates about the axis  116 . As a portion of the liquid advances through the gap  188 , its angular velocity increases relative to its previous velocity as well as relative to the portion of liquid that does not advance through the gap  188  and an increased shear force zone  190  ( FIG. 5 ) is formed by the significant increase in angular velocity of the liquid in the relatively short distance between the first artificial boundary  180  and the rotating filter  130 . 
     As the first artificial boundary  180  is stationary, the liquid in contact with the first artificial boundary  180  is also stationary or has no rotational speed. The liquid in contact with the upstream surface  146  has the same angular speed as the rotating filter  130 , which is generally in the range of 3000 rpm, which may vary between 1000 to 5000 rpm. The speed of rotation is not limiting to the present disclosure. The liquid in the increased shear zone  190  has an angular speed profile of zero where it is constrained at the first artificial boundary  180  to approximately 3000 rpm at the upstream surface  146 , which requires substantial angular acceleration, which locally generates the increased shear forces on the upstream surface  146 . Thus, the proximity of the first artificial boundary  180  to the rotating filter  130  causes an increase in the angular velocity of the liquid passing through the gap  188  and results in a shear force being applied on the upstream surface  146 . 
     This applied shear force aids in the removal of soils on the upstream surface  146  and is attributable to the interaction of the liquid and the rotating filter  130 . The increased shear zone  190  functions to remove and/or prevent soils from being trapped on the upstream surface  146 . The liquid passing between the first artificial boundary  180  and the rotating filter  130  applies a greater shear force on the upstream surface  146  than liquid in an absence of the first artificial boundary  180 . Further, an increase in shear force may occur on the downstream surface  148  where the artificial boundary  160  overlies the downstream surface  148 . The liquid would have an angular speed profile of zero at the artificial boundary  160  and would increase to approximately 3000 rpm at the downstream surface  148 , which generates the increased shear forces. 
     In addition to removing soils from the upstream surface  146 , the configuration of the artificial boundary  180  and its surface  183 , which is oriented at an angle relative to the axis  116 , acts to deflect soils near the upstream surface  146  toward one of the first and second ends  134 ,  136 . The end, which the soils may accumulate at, may depend on the rotational direction of the filter  130  and the angle of orientation of the artificial boundary  180 .  FIG. 6  illustrates a top view of the filter  130  and artificial boundary  180  and more clearly illustrates that the artificial boundary  180  has a surface  183 , which is oriented at an angle relative to the axis  116  and is linear from the first end  134  to the second end  136 . During operation, soils will naturally come in contact with the artificial boundary  180  as the liquid with soils in the filter chamber  82  rotate about the filter chamber  82 . Further, soils that may have been removed from the filter  130  by the shear forces created by the artificial boundary  180  may also come in contact with the artificial boundary  180  after removal because centrifugal force will urge the soils away from the filter  130  towards the housing  62 . Soils in contact with the surface  183  will be deflected along the surface  183  towards the second end  136  because a portion of the rotating water flow caused by the rotating water will contact the surface  183  and flow along the angled orientation of the surface  183 . The soils will be drawn along the surface  183  towards the end  136  where the soils may then accumulate. Essentially, the configuration of the artificial boundary  180  encourages a movement of soils to the end  136 . The drain outlet  72  is located near the end  136  such that soil, which has accumulated at the end  136 , may be easily pumped out of the housing  62 . 
     It should be noted that while the filter  130  has been described as rotating in the counter-clockwise direction and the artificial boundary  180  has been described as herding soils to the end  136  it may be understood that the assembly may be configured to have the filter rotate in a clockwise direction with the impeller or have the artificial boundary  180  oriented to direct the soils to the first end  134 . Regardless of which end the soils are herded towards, the drain outlet  72  may be located near the end the soils accumulate at for ease of removal of the soils from the filter chamber  82 . 
       FIG. 7  illustrates a top view of an alternative artificial boundary  280  according to a second embodiment. The alternative artificial boundary  280  also has a surface  283 , which is oriented at an angle relative to the axis  116  and may act to deflect soils near the upstream surface  146  toward one of the first and second ends  134 ,  136  where the soils may then accumulate at that end. The difference between the first embodiment and the second embodiment is that the surface of the artificial boundary  280  is helical instead of linear. It is contemplated that the artificial boundaries may have other alternative shapes so long as the surface is oriented at an angle relative to the central axis  116  such that soils near the upstream surface are deflected toward one of the first and second ends  134 ,  136 . Further, the internal artificial boundaries may have complementary shapes or cross-sections, which may act to enhance the shear force benefit. The second embodiment operates much the same way as the first embodiment. That is, the rotation of the filter  130  about the axis  116  causes the liquid and soil particles to rotate about the axis  116 . Centrifugal forces push the liquid and soils towards the outside and soils, which come in contact with the surface  283 , are deflected by force vectors towards the end  136 . 
       FIGS. 8 and 9  illustrate an alternative pump and filter assembly according to a third embodiment. The third embodiment is similar in some aspects to the first embodiment; therefore, like parts will be identified with like numerals increased by 300, with it being understood that the description of the like parts of the first embodiment applies to the third embodiment, unless otherwise noted. 
     The pump and filter assembly  334  includes a modified filter casing or filter housing  362 , a wash or recirculation pump  360 , a rotating filter  430 , internal artificial boundaries  460 , and external artificial boundaries  480 . The filter housing  362  defines a filter chamber  382  that extends the length of the filter casing  362  and includes an inlet port  370 , a drain outlet port  372 , and a recirculation outlet port  374 . It is contemplated that the drain outlet port  372  may be formed directly in the housing  362  and may be fluidly coupled to a drain pump (not shown) to drain liquid and soils from the dishwasher  10 . The recirculation pump  360  also includes an impeller  304 , which has several pins  492  that may be received within openings  494  in the end  436  of the filter  430  such that the filter  430  may be operably coupled to the impeller  304  such that rotation of the impeller  304  effects the rotation of the filter  430 . 
     The rotating filter  430  is similar to that of the first embodiment except that it has a first end  434  axially spaced from a second end  436  that is larger in diameter than the first end  434 . This forms a cone-shaped filter  430  that has a central axis corresponding to the rotational axis  316 . A cone shaped filter sheet may extend between the two ends  434  and  436  and may have an upstream surface  446  correlating to the outer surface and a downstream surface  448  correlating to the inner surface as described with respect to the above embodiment. A bearing  496  may be used to rotatably mount the first end  434  of the filter  430  to the housing  362  such that the filter  430  is free to rotate in the bearing  496  about the axis  316  in response to rotation of the impeller  304 . 
     The internal artificial boundary  460  may be located internally of the filter  430  and may be positioned adjacent to the downstream surface  448  and may be secured by a shaft  474  to the housing  362 . Suitable artificial flow boundaries are set forth in detail in U.S. patent application Ser. No. 12/966,420, filed Dec. 13, 2010, now U.S. Pat. No. 8,667,974, and titled “Rotating Filter for a Dishwashing Machine,” which is incorporated herein by reference in its entirety. The bearing  496  may rotatably receive the stationary shaft  474 , which in turn is mounted to the artificial boundary  460 . Thus, the artificial boundary  460  may be stationary while the filter  430  is free to rotate. Further, an increase in shear force may occur on the downstream surface  448  where the artificial boundary  460  overlies the downstream surface  448 . The liquid would have an angular speed profile of zero at the artificial boundary  460  and would increase to approximately 3000 rpm at the downstream surface  448 , which generates the increased shear forces. 
     The artificial boundaries  480  may be located such that they are overlying and spaced from at least a portion of the upstream surface  446  to form an increased shear force zone as described with respect to the first embodiment. The artificial boundaries  480  apply a greater shear force on the upstream surface  446  than liquid in an absence of the first artificial boundary. The artificial boundaries  480  may be mounted to the housing  362 . The artificial boundary  480  may be positioned in a partially or completely radial overlapping relationship with the artificial boundary  460  and spaced apart from the artificial boundary  480 . In some cases, the shear zone benefit may be created with the artificial boundaries being in proximity to each other and not radially overlapping to any extent. 
     It is contemplated that the artificial boundaries  460  and  480  may be fixed relative to the filter  430 , as illustrated, or that they may move relative to the filter  430 . Suitable mechanisms for moving the artificial boundary  460  and/or the artificial boundary  480  are set forth in detail in U.S. patent application Ser. No. 13/108,026, filed May 16, 2011, now U.S. Pat. No. 9,107,559, and titled “Dishwasher with Filter Assembly,” which is incorporated herein by reference in its entirety. 
     The third embodiment operates much the same as the above-described first embodiment in that when the impeller  304  is rotated the filter  430  is also rotated. The rotation of the impeller  304  draws liquid from the filter chamber  382  into the inlet opening of the impeller  304 . The liquid is then forced out through the recirculation outlet port  374  to the spray system. The recirculation pump  360  is fluidly coupled downstream of the downstream surface  448  of the filter  430  at the second end  436  and if the recirculation pump  360  is shut off then any liquid not expelled will settle in the filter chamber  382  and may be drained by the drain pump through the drain outlet port  372 . 
     One main difference in the operation is that the rotation of the cone filter  430  generates a soil flow from the first end  434  to the second end  436 . That is, soil  498 , which is filtered from the liquid and residing on the upstream surface  446 , is urged by the soil flow toward the second end  436 , even without the use of the first artificial boundary  480 , because of a flow path that develops from the first end  434  to the second end  436 . It will be understood that the filter  430  as a whole is rotated by the impeller  304  at a single rotational speed. Thus, all points on the filter  430  have the same rotational speed. However, because the diameter of the cone filter continuously increases from the first end  434  to the larger diameter second end  436 , the tangential velocity (illustrated by the arrows on  FIG. 10 ) increases axially from the first end  434  to the second end  436  for any point on the upstream surface  446 . The increase in the tangential velocity necessarily requires a corresponding increase in the tangential acceleration. 
     As such, the tangential acceleration increases from the first end  434  to the second end  436 , which creates a soil flow from the first end  434  to the second end  436  when the acceleration rate is great enough to overcome other forces, such as gravity acting on the suspended soils, which would tend to draw the soils down toward the small end  434  for a horizontally oriented filter as illustrated. For the contemplated rotational speed range (1000 rpm to 5000 rpm) for the illustrated cone filter  430 , the resulting tangential acceleration is great enough to form the soil flow from the first end  434  to the second end  436 . Therefore, rotation of the cone filter  430  alone is sufficient to move the soils toward one end, the large end  436 , of the filter  430 , when the filter  430  is rotated at a high enough speed. 
       FIG. 11  illustrates a top view of an alternative artificial boundary  580  according to a fourth embodiment, which may be used with the cone-filter  430  described above. The artificial boundary  580 , much like the first embodiment, has a linear surface  583 , which is oriented at an angle relative to the axis  416  and may act to deflect soils near the upstream surface  446  toward the second end  436  where the soils may then accumulate at that end. The difference between the third embodiment and the fourth embodiment is that the orientation of the surface  583  of the artificial boundary  580  acts to deflect the soils towards the end  436  along with the soil flow already created by the cone shape filter  430  itself, which also directs the soils towards the second end  436 . Thus, the shape of the rotating filter  430  and the surface  583  being oriented at an angle relative to the central axis  416  both act together to deflect soils towards the second end  436 . 
       FIG. 12  illustrates a top view of an alternative artificial boundary  680  according to a fifth embodiment. Much like the fourth embodiment, the artificial boundary  680  has a surface  683 , which is oriented at an angle relative to the axis  416  and may act to deflect soils near the upstream surface  446  toward the second end  436  where the soils may then accumulate at that end. The difference between the fourth embodiment and the fifth embodiment is that the surface  683  of the artificial boundary  680  is helical instead of linear. It too acts together with the soil flow created by the cone shaped filter  430  to deflect soils towards the second end  436 . 
     It is contemplated that the artificial boundary or artificial boundaries may have other alternative shapes so long as the surface is oriented at an angle relative to the central axis of the filter such that soils near the upstream surface are deflected toward one of the first and second ends. It likely is understood, but aspects of the various embodiments may be combined in any desired manner to accomplish a desired utility. By way of non-limiting example, various aspects of the first embodiment may be combined with the later embodiments as desired to accomplish the inclusion of internal artificial boundaries and to effect rotation of either or both of the artificial boundaries relative to the filter. 
     In the home appliance industry, sound is an important consideration as a user&#39;s satisfaction with the appliance may be hindered with increased appliance noise. While the filter and flow diverters allow for excellent filtration of soils from recirculated liquid the use of the artificial boundaries, under certain conditions and/or configurations, they may increase the sound produced by the dishwasher. The remaining embodiments describe a variety of ways to reduce the amount of sound created by a dishwasher having a filter and artificial boundaries. 
       FIG. 13  illustrates alternative artificial boundaries  760  and  780  according to a sixth embodiment. The alternative artificial boundaries  760  and  780  are illustrated in the context of the pump and filter assembly illustrated in  FIG. 3  of the first embodiment and the numbers of those parts have not been changed. The alternative artificial boundaries  760  and  780  are similar in some aspects to the artificial boundaries of the first embodiment; 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 seventh embodiment, unless otherwise noted. 
     As with the first embodiment the artificial boundary  760  is shaped such that it is not aligned or parallel with the axis of rotation  116  of the filter  130 . A first difference is that the artificial boundary  760  is also illustrated as having multiple segmented portions  761  forming its body  782 . In this manner, the artificial boundary  760  does not extend continuously along a length of the filter  130 . Further, the artificial boundary  760  is oriented at an angle relative to the axis  116 , as described above. The multiple segmented portions  761  of the artificial boundary  760  are positioned in the hollow interior  142  of the filter  130  and are spaced from the filter  130  to form gaps  766  there between. In the illustrated example, the multiple segmented portions  761  of the artificial boundary  760  are spaced such that there is a space  768  between the multiple segmented portions  761  of the artificial boundary  760 . 
     Another difference is that the artificial boundary  780  also has a body  782  having multiple segmented portions  781 , which are also oriented at an angle relative to the axis  116  such that they extend along the rotating filter such that they are not aligned with the rotational axis  116  of the filter  130 . This aids in decreasing the sound created during operation. In this manner, the artificial boundary  780  is also shaped such that it does not extend continuously along a length of the filter body and is not parallel with the rotational axis  116 . Each of the multiple segmented portions  781  is spaced from at least a portion of the filter  130  to form gaps  788  there between, which creates increased shear force zones as described above. The artificial boundary  780  and the artificial boundary  760  may be oriented with respect to each other in any suitable manner including that the artificial boundary  780  may be positioned in a partially or completely overlapping relationship with the artificial boundary  760 . In some cases, the shear zone benefit may be created with the artificial boundaries being in proximity to each other and not overlapping to any extent. The artificial boundaries  760  and  780  may have complementary shapes or cross-sections, which act to enhance the shear force benefit. Further, while each of the multiple segmented portions  781  has been illustrated as overlapping another along a length of the filter  130  this need not be the case. Instead, only a few of the multiple segmented portions  781  may overlap or the multiple segmented portions  781  may be spaced from each other. 
     The operation of the sixth embodiment is similar to that of the first embodiment. Including that, soils will naturally come in contact with the artificial boundary  780  as the liquid with soils in the filter chamber  82  rotate about the filter chamber  82 . Further, soils that may have been removed from the filter  130  by the shear forces created by the artificial boundary  780  may also come in contact with the artificial boundary  780  after removal because centrifugal force will urge the soils away from the filter  130  towards the housing  62 . Soils may be deflected towards the second end  136  because a portion of the rotating water flow caused by the rotating water will contact the artificial boundary  780  and flow along the angled orientation of the artificial boundary  780 . Further, during operation the artificial boundary  760  and the artificial boundary  780  result in less noise as the frequency and overall decibels are reduced as compared to a diverter that runs along an axial length of the filter. 
       FIG. 14  illustrates an alternative artificial boundary according to a seventh embodiment. The seventh embodiment is similar in some aspects to the sixth embodiment; therefore, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the sixth embodiment applies to the seventh embodiment, unless otherwise noted. 
     One difference is that the artificial boundary  880  has been illustrated as helical instead of linear. The helical nature of the artificial boundary  880  is such that it is not aligned with the rotational axis  116  of the filter  130 . It is contemplated that the artificial boundaries, either interior or exterior of the filter  130  may have other alternative shapes so long as the artificial boundary is not aligned with the rotational axis of the filter. Further, while only a first artificial boundary  880  is illustrated, a second artificial boundary could be included and be spaced from the other surface of the filter  130 . Further, any second artificial boundaries spaced from the other of the surfaces of the filter  130  may have complementary shapes or cross-sections, which may act to enhance the shear force benefit. Further, any second artificial boundaries spaced from the other of the surfaces may also not be aligned with the rotational axis  116  of the filter  130  to aid in decreasing the sound created during operation. Further still, the artificial boundary  880  has been illustrated as having two multiple segmented portions  881 , which overlap along a portion  884  of the filter  130 . In this manner, the artificial boundary  880  does not extend continuously along the filter  130 . The seventh embodiment operates much the same way as the sixth embodiment. 
       FIG. 15  illustrates an alternative artificial boundary according to an eighth embodiment. The alternative artificial boundary  980  is illustrated in the context of the pump and filter assembly of the third embodiment and the numbers of those parts have not been changed. The alternative artificial boundary  980  is similar in some aspects to the artificial boundary  880  of the seventh embodiment; therefore, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the third and seventh embodiments applies to the eighth embodiment, unless otherwise noted. 
     The difference being that the artificial boundary  980  is shaped such that it follows the contours of the cone-shaped filter  430 . As with the previous embodiment, the artificial boundary  980  is helical and is not aligned with the rotational axis  416  of the filter  430 . The artificial boundary  980  also does not extend continuously along a length of the filter  430  to aid in decreasing the sound created during operation. Further, the artificial boundary  980  has been illustrated as having two multiple segmented portions  981 , which overlap along a portion  984  of the filter  430 . 
     It will be understood for the above embodiments having multiple segmented portions forming the artificial boundaries that the multiple segmented portions may be much smaller and/or that the spaces or overlapping portions between the multiple segmented portions along the length of the filter may be much smaller or much larger and need not be the same. Further still, multiple interior and exterior artificial boundaries may be utilized. Thus, it will be understood that the drawings are merely exemplary. 
       FIG. 16  illustrates alternative artificial boundaries  1060  and  1080  according to a ninth embodiment. The alternative artificial boundaries  1060  and  1080  are illustrated in the context of the pump and filter assembly illustrated in  FIG. 3  of the first embodiment and the numbers of those parts have not been changed. The alternative artificial boundaries  1060  and  1080  are similar in some aspects to the artificial boundaries of the second embodiment; 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 and second embodiments applies to the ninth embodiment, unless otherwise noted. One difference is that the internal artificial boundary  1060  has been illustrated as a complementary helical shape to that of the artificial boundary  1080 . In this manner, both artificial boundaries have been shaped such that while they are continuous they do not align with the rotational axis  116  of the filter  130 , which aids in decreasing the sound created during operation. 
     While the helical artificial boundaries  1060  and  1080  have been illustrated as being utilized with the cylindrical filter  130  it will be understood that they may be utilized with any suitably shaped filter including a cone-shaped filter wherein the helical artificial boundaries may be contoured to the cone shape. Further still, the use of only a single artificial boundary may reduce the noise created as a smaller number of shear force zones would be created. 
     While the embodiments have been illustrated in the above manner, it will be understood that the advantages of sound reduction achieved when an artificial boundary is not aligned with the rotational axis of the filter may be realized in a variety of different configurations. Thus, it will be understood that the present disclosure may include any suitable rotating filter having opposing first and second surfaces with the rotating filter being positioned within the recirculation flow path to filter soils from liquid flowing through the fluid flow path as the liquid passes through the rotating filter between the first and second surfaces. For example, the rotating filter may be a hollow rotating filter shaped like a cylinder, cone, etc. or the rotating filter may be a rotating disk, other non-hollow shape, etc. Further still, any number and type of flow diverters may be used including that the flow diverters may have various shapes as described in detail in the U.S. patent application Ser. No. 14/268,282, filed May 2, 2014, now U.S. Pat. No. 9,375,129, and entitled Rotating Filter for a Dishwashing Machine, which is incorporated by reference herein in its entirety. 
     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 allows for enhanced filtration such that soil is filtered from the liquid and not re-deposited on utensils. Further, 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 still, a reduction in sound may be realized by the present disclosure, which results in increased user satisfaction. 
     To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments is not meant to be construed that it may not be, but is done for brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure. 
     Further still, in the above-described embodiments it is contemplated that the filter may be stationary and that the flow diverters may rotate as set forth in detail in U.S. patent application Ser. No. 13/108,026, filed May 16, 2011, now U.S. Pat. No. 9,107,559, and titled “Dishwasher with Filter Assembly,” which is incorporated herein by reference in its entirety. In such an instance the filter is located within the recirculation flow path such that the sprayed liquid passes through the filter to effect a filtering of the sprayed liquid and at least one flow diverter that is not aligned with the central axis of the filter moves over at least a portion of the outer and/or inner surfaces of the filter to form an increased shear force zone there between. 
     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.