Patent Publication Number: US-11382484-B2

Title: Dishwashing appliance and electric motor for a fluid pump with a thermal-protection assembly

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to dishwashing appliances and more particularly to dishwashing appliances having electric motors with one or more for features for thermal protection. 
     BACKGROUND OF THE INVENTION 
     Dishwashers or dishwashing appliances generally include a tub that defines a wash chamber for receipt of articles for washing. A door provides or permits selective access to the wash chamber. During wash and rinse cycles, dishwashing appliances generally circulate a fluid through a wash chamber over articles, such as pots, pans, silverware, etc. The fluid can be, for example, various combinations of water and detergent during the wash cycle or water (which may include additives) during the rinse cycle. After the rinse cycle is complete, a drain cycle can be performed to remove the fluid from the wash chamber. Typically, one or more pumps are provided to motivate the fluid through or from the wash chamber. For example, the fluid within a dishwashing appliance is typically circulated during a given cycle using a circulation pump. Fluid is collected in a sump at or near a bottom of the wash chamber and pumped back into the wash chamber through, for example, nozzles in spray arms and other openings that direct the fluid against the articles to be cleaned or rinsed. After the rinse cycle is complete, the drain pump may be activated to pump fluid out of the wash chamber. 
     Often, circulation and drain pumps are mounted directly to the tub defining a wash chamber. A water tight seal is generally required between a pump and the tub. This need to a water tight seal can lead to further issues. For instance, great care must be taken when connecting a circulation or drain pump (e.g., an electric motor thereof) to a power source since any opening formed through the pump may risk introducing a leak point wherein moisture may be introduced to an undesired location of the pump, such as an electric motor. This may be especially true if the electric motor is mounted within an often liquid-filled portion of the dishwashing appliance. 
     Separate from or in addition to issues regarding the prevention of moisture to an electric motor, issues may arise concerning heat management. For instance, features may be needed to prevent the electric motor from inadvertently overheating. Attempts have been made to provide thermal switches on or near an electric motor within a dishwashing appliance. Existing attempts generally require complex wiring and often require additional openings through the pump, which may create more potential leak points. In turn, such existing attempts are often unreliable or otherwise unsatisfactory. 
     As a result, it would be useful to provide a dishwashing appliance addressing one or more of the above identified issues. In particular, it may be advantageous to provide a dishwashing appliance that includes features for providing thermal protection without creating additional opening or potential leak points. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one exemplary aspect of the present disclosure, a fluid pump for a dishwashing appliance is provided. The fluid pump may include a fluid impeller, an electric motor, and a housing. The fluid impeller may be rotatably receivable within a tub of the dishwashing appliance. The electric motor may be in mechanical communication with the fluid impeller to motivate rotation thereof. The electric motor may include a multi-phase winding set sealed within an overmolded insulation. The housing may enclose the electric motor therein. The housing may be receivable within a sump to which water is directed in the dishwashing appliance. 
     In another exemplary aspect of the present disclosure, a dishwashing appliance is provided. The dishwashing appliance may include a tub, a sump, and a fluid pump. The tub may define a wash chamber. The sump may be positioned at a bottom portion of the tub along a vertical direction. The sump may include a bottom wall defining a recessed chamber. The fluid pump may be in fluid communication with the sump to motivate a fluid therefrom. The fluid pump may include a fluid impeller, an electric motor, and housing. The fluid impeller may be rotatably positioned within the tub. The electric motor may be in mechanical communication with the fluid impeller to motivate rotation thereof. The electric motor may include a multi-phase winding set sealed within an overmolded insulation. The housing may enclose the electric motor therein. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures. 
         FIG. 1  provides a front perspective view of a dishwashing appliance according to exemplary embodiments of the present disclosure. 
         FIG. 2  provides a side, cross-sectional view of the exemplary dishwashing appliance of  FIG. 1 . 
         FIG. 3  provides a cross-sectional view of a sump of the exemplary dishwashing appliance of  FIG. 1 . 
         FIG. 4  provides a side perspective view of a pump assembly of the exemplary dishwashing appliance of  FIG. 1 . 
         FIG. 5  provides a bottom perspective view of the exemplary pump assembly of  FIG. 4 . 
         FIG. 6  provides a bottom perspective view of the exemplary sump of  FIG. 3 , with the pump partially removed therefrom and a bottom portion of the sump removed for the sake of clarity. 
         FIG. 7  provides a cross-sectional view of the exemplary sump of  FIG. 3  during a circulation cycle. 
         FIG. 8  provides a cross-sectional view of the exemplary sump of  FIG. 3  during a drain cycle. 
         FIG. 9  provides a cross-sectional view of a portion of the exemplary pump assembly of  FIG. 4 . 
         FIG. 10  provides a cross-sectional view of a portion of the exemplary pump assembly of  FIG. 4 , wherein a portion has been removed for clarity. 
         FIG. 11  provides a magnified perspective view of a plurality of vanes of the exemplary pump assembly of  FIG. 4 . 
         FIG. 12  provides a perspective view of a lower portion of the exemplary pump assembly of  FIG. 4 . 
         FIG. 12  provides a perspective view of a lower portion of the exemplary pump assembly of  FIG. 4 . 
         FIG. 13  provides a top perspective view of a lower portion of a vane of the exemplary pump assembly of  FIG. 4 . 
         FIG. 14  provides a perspective view of a lower inner portion of the exemplary pump assembly of  FIG. 4 . 
         FIG. 15  provides a perspective view of a lower outer portion of the exemplary pump assembly of  FIG. 4 . 
         FIG. 16  provides a perspective view of a portion of the exemplary pump assembly of  FIG. 4 , including the electric motor thereof. 
         FIG. 17  provides a perspective view of a portion of the electric motor of the exemplary pump assembly of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). The terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the flow direction from which the fluid flows, and “downstream” refers to the flow direction to which the fluid flows. 
       FIGS. 1 and 2  depict a dishwashing appliance  100  according to an exemplary embodiment of the present disclosure. As shown in  FIG. 1 , dishwashing appliance  100  includes a cabinet  102 . Cabinet  102  has a tub  104  therein that defines a wash compartment  106 . The tub  104  also defines a front opening (not shown). Dishwashing appliance  100  includes a door  120  hinged at a bottom  122  of door  120  for movement between a normally closed, vertical position (shown in  FIGS. 1 and 2 ), wherein wash compartment  106  is sealed shut for washing operation, and a horizontal, open position for loading and unloading of articles from dishwashing appliance  100 . In some embodiments, a latch  123  is used to lock and unlock door  120  for access to wash compartment  106 . Tub  104  also includes a sump  170  positioned adjacent a bottom portion  112  of tub  104  and configured for receipt of a liquid wash fluid (e.g., water, detergent, wash fluid, or any other suitable fluid) during operation of dishwashing appliance  100 . 
     In certain embodiments, a spout  160  is positioned adjacent sump  170  of dishwashing appliance  100 . Spout  160  is configured for directing liquid into sump  170 . Spout  160  may receive liquid from, for example, a water supply (not shown) or any other suitable source. In alternative embodiments, spout  160  may be positioned at any suitable location within dishwashing appliance  100  (e.g., such that spout  160  directs liquid into tub  104 ). Spout  160  may include a valve (not shown) such that liquid may be selectively directed into tub  104 . Thus, for example, during the cycles described below, spout  160  may selectively direct water or wash fluid into sump  170  as required by the current cycle of dishwashing appliance  100 . 
     Rack assemblies  130  and  132  may be slidably mounted within wash compartment  106 . In some embodiments, each of the rack assemblies  130  and  132  is fabricated into lattice structures including a plurality of elongated members  134 . Each rack of the rack assemblies  130  and  132  is generally adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash compartment  106 , and a retracted position (shown in  FIGS. 1 and 2 ) in which the rack is located inside the wash compartment  106 . A silverware basket (not shown) may be removably attached to rack assembly  132  for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by the racks  130  and  132 . 
     In certain embodiments, dishwashing appliance  100  includes a lower spray assembly  144  that is rotatably mounted within a lower region  146  of the wash compartment  106  and above sump  170  so as to rotate in relatively close proximity to rack assembly  132 . Optionally, a mid-level spray assembly  148  is located in an upper region of the wash compartment  106  and may be located in close proximity to upper rack  130 . Additionally or alternatively, an upper spray assembly  150  may be located above the upper rack  130 . 
     In exemplary embodiments, lower and mid-level spray assemblies  144  and  148  and the upper spray assembly  150  are fed by a fluid circulation assembly  152  for circulating water and dishwasher fluid in the tub  104 . Fluid circulation assembly  152  includes one or more fluid pumps (e.g., a circulation pump  154  or a cross-flow/drain pump  156 ). As will be discussed in greater detail below, some embodiments include circulation pump  154  positioned at least partially within sump  170  and drain pump positioned below circulation pump  154  in fluid communication with sump  170 . Additionally, drain pump  156  may be configured for urging the flow of wash fluid from sump  170  to a drain  158  when activated. By contrast, circulation pump  154  may be configured for supplying a flow of wash fluid from sump  170  to spray assemblies  144 ,  148  and  150  by way of one or more circulation conduits  226  when activated. Moreover, a filter assembly may be also positioned at least partially in sump  170  for filtering food particles or other debris, referred to herein generally as soils, from wash fluid prior to such wash fluid flowing to circulation pump  154 . 
     Spray assemblies  144  and  148  include an arrangement of discharge nozzles or orifices for directing wash fluid onto dishes or other articles located in rack assemblies  130  and  132 . The arrangement of the discharge nozzles in spray assemblies  144  and  148  provides a rotational force by virtue of wash fluid flowing through the discharge ports. The resultant rotation of the spray assemblies  144  and  148  provides coverage of dishes and other dishwasher contents with a spray of wash fluid. 
     Dishwashing appliance  100  is further equipped with a controller  137  to regulate operation of the dishwashing appliance  100 . Controller  137  may include a memory (e.g., non-transitive media) and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a washing operation. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller  137  may be constructed without using a microprocessor (e.g., using a combination of discrete analog or digital logic circuitry, such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. 
     Controller  137  may be positioned in a variety of locations throughout dishwashing appliance  100 . In the illustrated embodiment, controller  137  may be located within a control panel area  121  of door  120  as shown. In such an embodiment, input/output (“I/O”) signals may be routed between controller  137  and various operational components of dishwashing appliance  100  along wiring harnesses that may be routed through the bottom  122  of door  120 . Typically, controller  137  includes a user interface panel  136  through which a user may select various operational features and modes and monitor progress of the dishwashing appliance  100 . In one embodiment, user interface  136  may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, user interface  136  may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. User interface  136  may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. User interface  136  may be in communication (e.g., electrical or wired communication) with controller  137  via one or more signal lines or shared communication busses. 
     It should be appreciated that the subject matter disclosed herein is not limited to any particular style, model or configuration of dishwashing appliance, and that the embodiment depicted in the figures is for illustrative purposes only. For example, instead of the racks  130  and  132  depicted in  FIG. 1 , dishwashing appliance  100  may be of a known configuration that utilizes drawers that pull out from the cabinet and are accessible from the top for loading and unloading of articles. 
     Turning now to  FIGS. 3 through 15 ,  FIGS. 3 and 6 through 8  provide various views of the sump  170 , including a pump assembly  200  and housing  234  therefor.  FIGS. 4 and 5  provide various views of portions of the pump assembly  200  in isolation from sump  170 .  FIGS. 9 through 15  provide various views of portions of the pump assembly  200 , including a chamber pump housing  234 .  FIGS. 16 and 17  provide various views of further portions of the pump assembly  200 , including an electric motor  242  thereof. 
     As noted above, sump  170  is positioned at a bottom portion  112  of tub  104  ( FIG. 2 ) along the vertical direction V. Sump  170  defines an axial direction A that may be, for example, parallel to the vertical direction V. Optionally, sump  170  is formed integrally with a bottom wall  142  of tub  104 . However, in other embodiments, sump  170  may instead be formed separately from bottom wall  142  of tub  104  and attached to bottom wall  142  of tub  104  in any suitable manner. Additionally, sump  170  may have any other suitable orientation. 
     As shown, sump  170  includes a side wall  202  and a bottom wall  204 . Sidewall  202  may define a substantially cylindrical shape along the axial direction A, although in other embodiments, sidewall  202  may instead define any other suitable shape, such as a frustoconical shape, or alternatively an inverted frustoconical shape along the axial direction A. 
     In exemplary embodiments, bottom wall  204  extends radially inward from sidewall  202  and defines a recessed chamber  206  bounded by walls  202 ,  204 . Recessed chamber  206  is defined at its perimeter by a rim portion of bottom wall  204  extending downward generally downward (e.g., toward the axial direction A or parallel thereto). Recessed chamber  206  also defines an opening  210  having, for example, a generally circular shape. Moreover, bottom wall  204  defines a drain opening  208  in a portion that opens into the recessed chamber  206 . 
     In some embodiments, a filter assembly is positioned at least partially within sump  170  along the axial direction A (e.g., with or as a portion of pump assembly  200 ). The filter assembly may include multiple panels, such as a side panel  212 , a bottom panel  214 , or a top panel (not pictured). One or more of side panel  212 , bottom panel  214 , and top panel may include a filter medium defining a plurality of openings or pores configured to allow wash fluid to pass therethrough while preventing soils, such as food particles or other debris, larger than a predetermined size to pass therethrough. For example, in certain embodiments, one or more of side panel  212 , bottom panel  214 , and the top panel may include a fine mesh material. 
     In exemplary embodiments, a circulation pump  154  is included within pump assembly  200 . More particularly, circulation pump  154  includes a fluid impeller (e.g., circulation impeller  232 ) and a chamber pump housing  234 . When assembled, circulation impeller  232  is positioned within pump assembly  200  and is enclosed by chamber pump housing  234 . In some embodiments, circulation pump  154 , including chamber pump housing  234 , is held in position along the axial direction A by one or more elastomer columns  222 . In certain embodiments, pump housing  234  defines a plurality of guide veins  236  that are downstream of impeller  232  and in fluid communication with circulation conduit  226  ( FIG. 2 ). Guide veins  236  may thus direct a flow F of wash fluid from circulation impeller  232  to the circulation conduit  226  (e.g., during a circulation cycle). In exemplary embodiments, circulation pump  154  is positioned at least partially within the filter assembly (e.g., within one or more of the panels thereof). 
     As will be further described below, in optional embodiments, pump housing  234  defines a plurality of internal channels  236  that are downstream of impeller  232  and in fluid communication with circulation conduit  226  ( FIG. 2 ). Thus, internal channels  236  are in fluid communication with one or more of the spray assemblies  142 ,  148 ,  150 ). Internal channels  236  may direct a flow F of wash fluid from circulation impeller  232  to the circulation conduit  226  (e.g., during a circulation cycle). One or more diffuser vanes  270  extend (e.g., radially) within chamber pump housing  234  to convert a velocity head of flow F to a static head within internal channels  236 . In exemplary embodiments, circulation pump  154  is positioned at least partially within the filter assembly (e.g., within one or more of the panels thereof). 
     As illustrated, some embodiments include an electric motor  242  mounted within a portion of the sump  170 . For instance, the electric motor  242  may be enclosed within a portion of chamber pump housing  234  radially inward from the vane(s)  270 . In particular, a multi-phase winding set  320  of the electric motor  242  may be sealed within an inner cavity  322  defined by the chamber pump housing  234  (e.g., as a generally-toroidal chamber within an inner diffuser bowl  282 ). Within inner cavity  322 , an overmolded insulation  324  may cover the multi-phase winding set  320  inside inner cavity  322 , potting electric motor  242  such that multi-phase winding set  320  is sealed within the surrounding overmolded insulation  324 . Generally, the overmolded insulation  324  may be any suitable material (e.g., flowed to and hardened within inner cavity  322 ), such as an unsaturated polyester. Advantageously, the overmolded insulation  324  may hermitically seal and electrically insulate multi-phase winding set  320 , preventing multi-phase winding set  320  from being damaged if a portion of the chamber pump housing  234  ruptures to permit water or wash fluid to inner cavity  322 . 
     In some embodiments, the one or more elastomer columns  222  may generally vertically or otherwise parallel to the axial direction A between chamber pump housing  234  and the bottom wall  204  of sump  170 . More particularly, for the embodiment depicted, the one or more elastomer columns  222  extend from chamber pump housing  234  through recessed chamber  206  to bottom wall  204  of sump  170 . As shown, chamber pump housing  234  may be held or supported on the elastomer columns  222 . For instance, chamber pump housing  234  may include one or more support tubes  250  circumferentially positioned about chamber pump housing  234  (e.g., radially outward relative to guide veins  236 ). Each support tube  250  may generally correspond to and selectively receive one of the elastomer columns  222 . When received within the support tubes  250 , elastomer columns  222  may provide supportive engagement with the chamber pump housing  234 . In particular, substantially all of the mass or weight of chamber pump housing  234  may be directed to, or otherwise borne, by elastomer columns  222 . 
     Generally, a power line  326  extends through the chamber pump housing  234  to the electric motor  242 . Specifically, power line  326 , including one or more intermediate conductive wires or buses, extends in conductive or electrical communication with a power source (e.g., residential or commercial power grid) outside of dishwashing appliance  100 . When assembled, power line  326  may thus extend from an outer portion of dishwashing appliance  100  (e.g., at the power source), through chamber pump housing  234 , and to electric motor  242  to connect the power source to the electric motor  242 . For instance, the power line  326  may be a singular, sole electrical connection cord (e.g., including two or more lines for establishing or otherwise together providing an electrical circuit with electric motor  242 ) passing from an outer portion of chamber pump housing  234  to the electric motor  242 . Advantageously, there may be no further electrical connections extending to electric motor  242 , which might otherwise create potential leak points into which water or wash fluid may flow, thereby damaging electric motor  242 . 
     In optional embodiments, power line  326  extends through at least one elastomer column. As shown, the at least one elastomer column  222  and corresponding support tube  250  may form a mated electrical plug-socket  252  along power line  326 . For instance, at least one elastomer column  222  may include an electrical male plug  252 A, while corresponding support tube  250  includes an electrical female socket  252 B. Alternatively, the electrical male plug  252 A may be provided within the support tube  250  while the female socket  252 B is provided on or within the elastomer column  222 . Thus, the elastomer column  222  may be in conductive or electrical communication with the power source (e.g., through one or more intermediate conductive wires or buses). The support tube  250  may be in conductive or electrical communication with the electric motor  242 . When assembled, the mated electrical plug-socket  252  may connect the power source to the electric motor  242 . An electrical connection may thus be formed with the electric motor  242  through at least one elastomer column  222 . 
     In some embodiments, pump assembly  200  includes a drain pump  156 , which itself includes a fluid impeller (e.g., drain impeller  238 ) and a drain pump housing  240 . When assembled, drain impeller  238  may be enclosed by drain pump housing  240 , and drain pump housing  240  is attached to or otherwise formed by sump  170 . More particularly, drain pump housing  240  is positioned below and in fluid communication with the recessed chamber  206  defined by bottom wall  204  of sump  170  assembly through a drain opening  208  of bottom wall  204  of sump  170 . In certain exemplary embodiments, drain pump housing  240  may be formed integrally with sump  170 , or alternatively may be attached to sump  170  in any suitable manner. 
     As shown, a volute cover  254  may be positioned over or across at least a portion of drain opening  208 . In some embodiments, volute cover  254  is mounted to chamber pump housing  234  (e.g., via one or more adhesives, mechanical fasteners, or integral unitary members). When assembled, volute cover  254  may thus be positioned between electric motor  242  and drain impeller  238  (e.g., along the axial direction A). A cover opening or inlet  256  is defined through volute cover  254  (e.g., along the axial direction A or a direction that is parallel or otherwise nonorthogonal to the vertical direction V). Fluid communication and a flow F between recessed chamber  206  and drain pump housing  240  may thus be permitted through the cover inlet  256 . 
     In some embodiments, volute cover  254  includes a radial flange  258  (e.g., along a radial or outer perimeter of volute cover  254 ). For instance, radial flange  258  may be disposed about the axial direction A at a radial outermost portion of volute cover  254 . When assembled, radial flange  258  may be positioned, at least in part, above an elastomer seal  260  that extends about or around drain opening  208 . 
     As shown, an elastomer seal  260  may be mounted on sump  170  (e.g., on bottom wall  204 ) at a position that is generally higher than drain impeller  238  relative to the vertical direction V or axial direction A. Elastomer seal  260  may further be positioned, at least in part, between radial flange  258  and recessed chamber  206  (or between radial flange  258  and drain impeller  238 ) along the axial direction A. In some embodiments, elastomer seal  260  includes a ring support body and an interface surface extending therefrom. For instance, interface surface may extend radially inward from ring support body toward the axial direction A. 
     In some embodiments, pump assembly  200  includes an axial shaft  244  engaged (e.g., in mechanical communication) with electric motor  242 . During operations, axial shaft  244  may thus be rotated by electric motor  242 . As shown, electric motor  242  may be positioned above drain impeller  238  or circulation impeller  232  (e.g., along the vertical direction V or axial direction A). Moreover, circulation impeller  232  may be positioned above volute cover  254 . In exemplary embodiments, axial shaft  244  extends through circulation impeller  232 , through volute cover  254  (e.g., at cover inlet  256 ), and into drain impeller  238  along the axial direction A. Axial shaft  244  may be selectively engaged (e.g., in mechanical communication) with drain impeller  238  and circulation impeller  232 , such that rotation of axial shaft  244  rotates drain impeller  238  or rotates circulation impeller  232 . 
     In optional embodiments, circulation pump  154  may include a one-way clutch (not shown) in mechanical communication with circulation impeller  232  and axial shaft  244 . When axial shaft  244  is rotated in a first direction by electric motor  242 , the one-way clutch of circulation impeller  232  is configured to engage circulation impeller  232  and rotate circulation impeller  232 . Alternatively, circulation impeller  232  may be fixed to axial shaft  244  (e.g., such that rotation of axial shaft  242  in either a first or second direction rotates circulation impeller  232 ). 
     In additional or alternative embodiments, drain pump  156  further includes a one-way clutch  268  in mechanical communication with drain impeller  238  and axial shaft  244 . When axial shaft  244  is rotated in a second direction by electric motor  242 , the second direction being an opposite direction of the first direction, the one-way clutch  268  of the drain impeller  238  is configured to engage drain impeller  238  and rotate drain impeller  238 . In some such embodiments, only one of circulation pump  154  and drain pump  156  may be activated at a given time. Alternatively, drain impeller  238  may be fixed to axial shaft  244  (e.g., such that rotation of axial shaft  242  in either a first or second direction rotates drain impeller  238 ). 
     Advantageously, the present the filter assembly, including electric motor  242  and impellers  232 ,  238  may be assembled by lowering chamber pump housing  234  into sump  170 , without requiring a separate electric motor in an area below recessed chamber  206 , or without requiring access to the same. Additionally or alternatively, most, if not all, of the pump assembly  200  (e.g., electric motor  242 , chamber pump housing  234 , volute cover  254 , and impellers  232 ,  238 ) may be preassembled prior to being mounted within sump  170 . 
     Referring now particularly to  FIG. 7 , sump  170  is depicted during operation of circulation pump  154  ( FIG. 2 ), such as during a circulation cycle (e.g., wash or rinse cycle) of the exemplary dishwashing appliance  100 . During operation of circulation pump  154 , a passage  246  may be defined between bottom panel  214  of the filter assembly and bottom wall  204  of sump  170 . As shown, passage  246  may further extend between bottom panel  214  and volute cover  254 . Passage  246  generally allows for wash fluid to access bottom panel  214  of the filter assembly. Accordingly, during operation of circulation pump  154 , impeller  232  of circulation pump  154  may pull a flow of wash fluid F through the filter assembly (e.g., through the top panel, side panel  212 , or bottom panel  214 , such that wash fluid flows inwardly through the panels). From passage  246 , fluid may flow into chamber pump housing  234  through inlet  248 . Within chamber pump housing  234 , fluid may flow through internal channels  236  and past or over diffuser vanes  270 . The foil profile  272  of each diffuser vane  270  may serve to convert a velocity head of the fluid flow to a static head. From the internal channel  236 , fluid may continue to flow downstream (e.g., to one or more of the spray assemblies  142 ,  148 ,  150 ). 
     During operation of circulation pump  154 , soils in wash fluid may gravitate towards recessed chamber  206  defined in bottom wall  204  of sump  170 . For example, an inlet  248  of circulation pump  154  is positioned adjacent bottom panel  214  of the filter assembly, and thus wash fluid may first be pulled through bottom panel  214  of the filter assembly. Additionally or alternatively, as recessed chamber  206  is positioned at a bottom of sump  170 , gravitational forces may also cause soils to gravitate towards recessed chamber  206 . Such a configuration may allow for efficient draining and cleaning of sump  170 , as the drain opening  208  opens into recessed chamber  206  defined by bottom wall  204 . As shown, bottom wall  204  may include or be provided as a solid continuous surface. Thus, at least a portion of the bottom wall  204  (e.g., a lowermost surface thereof, which is directly beneath recessed chamber  206  and impeller  238 ) may be free of an openings or apertures (e.g., vertical openings) through which water may pass. 
     Referring now particularly to  FIG. 8 , sump  170  is depicted during operation of drain pump  156  ( FIG. 2 ), such as during a drain cycle of the exemplary dishwashing appliance  100 . During operation of drain pump  156 , a flow of wash fluid F may be pulled from sump  170  through recessed chamber  206  in bottom wall  204  of sump  170  and through drain pump opening  208  of bottom wall  204 . As many of the soils may be positioned in recessed chamber  206 , drain pump  156  may expel the soils previously gathered in recessed chamber  206  of bottom wall  204  more quickly and may leave less soils behind for subsequent cycles. 
     Turning now especially to  FIGS. 3, 4, and 9 through 15 , in some embodiments, one or more diffuser vanes  270  are provided within chamber pump housing  234 . Specifically, diffuser vanes  270  may be positioned within (e.g., to at least partially define) internal channels  236 . 
     As shown, each vane  270  generally extends (e.g., along the radial direction R) from an inner radial end  274  to an outer radial end  276 . Moreover, each diffuser vane  270  may define a foil profile  272 . In turn, the outer surface of each diffuser vane  270  is generally curved or nonlinear between a first axial end  278  and a second axial end  280 . The foil profile  272  may have a varied vane width or thickness (e.g., such that thickness of the foil profile  272  tapers between the two axial ends  278 ,  280 ) and generally serves to form a high-pressure side and a low pressure side. During use (e.g., during a circulation operation), fluid flow within chamber housing  234  may be directed within internal channels  236  according to a curved or relatively helical path about the axial direction A. 
     In certain embodiments, a discrete inner diffuser bowl  282  and outer diffuser bowl  284  are included with chamber pump housing  234 . As shown, inner diffuser bowl  282  is enclosed, at least in part, within outer diffuser bowl  284 . When assembled, at least a portion of inner diffuser bowl  282  and outer diffuser bowl  284  may be spaced apart (e.g., along the radial direction R) to define, for example, the radial bounds of internal channels  236 . For instance, internal channels  236  may be defined between an outer wall surface  286  of inner diffuser bowl  282  and an inner wall surface  288  of outer diffuser bowl  284 . As shown, outer diffuser bowl  284  may define inlet  248  (e.g., below inner diffuser bowl  282 ) and a downstream outlet  249  (e.g., above inner diffuser bowl  282  and in fluid communication with one or more of the spray assemblies  142 ,  148 ,  150 ). Thus, internal channels  236  may extend across inner diffuser bowl  282  within outer diffuser bowl  284 . Additionally or alternatively, impeller  232  may be housed within outer diffuser bowl  284  while remaining outside of inner diffuser bowl  282 . Optionally, motor  242  may located radially inward from the diffuser vanes  270 . For instance, motor  242  may be enclosed within inner diffuser bowl  282  and sealed from fluid communication with internal channels  236 . As shown, axial shaft  244  may extend from inner diffuser bowl  282  and out through outer diffuser bowl  284  (e.g., to simultaneously mechanically couple with impellers  232  and  238 ). 
     In some embodiments, each vane  270  is fixed to inner diffuser bowl  282  or outer diffuser bowl  284  while being selectively attached to the other bowl  284  or  282 . For instance, the inner radial end  274  of one or more vanes  270  may be formed on outer wall surface  286  of inner diffuser bowl  282  (e.g., as an integral monolithic or unitary structure). Outer radial end  276  of vane  270  may then be attached to outer diffuser bowl  284  (e.g., by a threaded engagement joint  290 ). 
     In the exemplary embodiments illustrated in  FIGS. 3, 4, and 9 through 15 , threaded engagement joint  290  selectively attaches the outer radial end  276  of vane  270  to inner wall surface  288  of outer diffuser bowl  284 . When assembled, threaded engagement joint  290  is thus formed between vane  270  and inner wall surface  288 . As shown, threaded engagement joint  290  includes a pair of complementary radial thread profiles  292 ,  294 . A first radial thread profile  292  extends (e.g., radially outward or radially inward) from the corresponding vane  270  at the outer radial end  276 , while a second radial thread profile  294  is formed on inner wall surface  288 . For example, first radial thread profile  292  may be male extrusion selectively received within the female groove of second radial thread profile  294 . Threaded engagement joint  290  may generally function as a screw, thus rotation of outer diffuser bowl  284  or inner diffuser bowl  282  about the axial direction A relative to the other bowl  282  or  284  may serve to interlock the radial thread profiles  292 ,  294  and attach the diffuser bowls  282 ,  284 . 
     Any suitable thread shape may be provided. For instance, when viewed along the cross-section perpendicular to the axial direction A, threaded engagement joint  290  may define an angled, blunt-nose thread shape (e.g., as illustrated in  FIG. 13 ). Alternatively, threaded engagement joint  290  may have a rounded thread shape (e.g., similar to a knuckle thread), a triangular thread shape (e.g., similar to a buttress thread), a square thread shape (e.g., similar to a square thread), etc. 
     It is noted that while the first radial thread profile  292  is illustrated as a male extrusion extending radially outward from the foil profile  272  of vane  270 , and the second radial thread profile  294  is illustrated as a female groove extending within outer diffuser bowl  284 , it is understood that this relationship may be reversed. In other words, the first radial thread profile  292  may be provided as female groove extending radially inward from a foil profile  272  and within the corresponding vane  270 , while the second thread profile is provided as a male extrusion extending radially inward from inner wall surface  288  of outer diffuser bowl  284 . 
     Although both of the foil profile  272  and the first radial thread profile  292  provided on or defined by a common vane  270 , each profile  272  or  292  may be unique from the other  292  or  272 . Specifically, the first radial thread profile  292  is defined along a set or constant helical path. The first radial thread profile  292  thus has a curve and thread pitch that does not change (e.g., along the axial direction A). Optionally, the thread thickness or diameter (e.g., in the axial direction A or radial direction R) may be constant. In contrast to the first radial thread profile  292 , the foil profile  272  may be defined along a varied or non-constant, curved path. The curve or angle of the foil profile  272  may thus change (e.g., along the axial direction A). Thus, the angle or shape of the foil profile  272  may be different at the second axial end  280  than the angle or shape of the foil profile  272  at the first axial end  278  (or at another portion of the foil profile  272  between the first axial end  278  and the second axial end  280 ). 
     In some embodiments, the first radial thread profile  292  is bounded within a radial cross-section of the foil profile  272 . Thus, when viewed along the radial direction R (e.g., such that a plane perpendicular to the radial direction R is visible), the first radial thread profile  292  may appear to be wholly enclosed within the foil profile  272 . In other words, the first radial thread profile  292  may be formed such that the non-radial extrema (i.e., extrema perpendicular to the radial direction R, such as the axial direction A) of the first radial thread profile  292  do not extend beyond the non-radial extrema defined by the corresponding foil profile  272  (e.g., at the outer radial end  276 ). 
     Advantageously, the threaded engagement joint  190  may establish a seal between vane  270  and inner wall surface  288  or otherwise prevent crossover leakage (e.g., between the high pressure and low pressure sides of vane  270 ). 
     In certain embodiments, one or more portions of chamber pump housing  234  are provided as discrete and separable upper and lower housing sections. As an example, inner diffuser bowl  282  may include an inner upper section  282 A that is selectively supported on an inner lower section  282 B. As an additional or alternative example, outer diffuser bowl  284  may include an outer upper section  284 A that is selectively supported on an outer lower section  284 B. Thus, one or both of the diffuser bowls  282 ,  284  may be selectively separated or attached (e.g., while advantageously providing a fluid seal at the attachment points thereof). 
     In certain embodiments wherein inner diffuser bowl  282  includes an inner upper section  282 A and an inner lower section  282 B, one or more of the vanes  270  includes multiple discrete and separable segments. For instance, vane  270  may include a lower segment  270 B fixed to the inner lower section  282 B and an upper segment  270 A fixed to the inner upper section  282 A. Each of lower segment  270 B and upper segment  270 A may define separate portions of the foil profile  272 . When the lower segment  270 B and the upper segment  270 A are attached together (e.g., in contact with each other) the foil profile  272  may be continuous across the entire vane  270 . In some such embodiments, a complementary groove—notch joint is formed between the lower and upper segments  270 B,  270 A. For instance, the lower segment  270 B may define an axial groove  296  (e.g., extending between inner radial end  274  and outer radial end  276 ) at a top surface of the lower segment  270 B. Similarly, the upper segment  270 A may define an axial notch  298  at a bottom surface of the upper segment  270 A. When assembled, the axial notch  298  may be mated with and received within the axial groove  296  such that relative rotation between the segments  270 A,  270 B (e.g., about the axial direction A) is prevented or restricted. 
     In additional or alternative embodiments wherein outer diffuser bowl  284  includes an outer upper section  284 A and an outer lower section  284 B, one or more the vanes  270  includes multiple threaded engagement joints  290 . For instance, a separate or unique threaded engagement joint  290 , each including a complementary first and second radial thread profiles  292 ,  294 , may be included with the upper and lower segments  270 A,  270 B of the vane  270 . Thus, a lower threaded engagement joint  290  may be formed between the outer lower section  284 B and the lower segment  270 B of the vane  270 . Moreover, an upper threaded engagement joint  290  may be formed between the outer upper section  284 A and the upper segment  270 A of the vane  270 . In some such embodiments, the first radial thread profile  292  of both the lower segment  270 B and the upper segment  270 A are bounded within the radial cross-section of the foil profile  272  (e.g., within the portion of the foil profile  272  defined by the corresponding segment  270 A,  270 B). 
     Optionally, lower and upper threaded engagement joints  290  may be defined along identical paths (e.g., such that radial thread profiles  292 ,  294  are defined according to the same thread pitch or size). Alternatively, and as illustrated, lower and upper threaded engagement joints  290  may each be unique. As an example, each threaded engagement joint  290  may define a different thread pitch (e.g., axial distance between one crest of a thread and another axially adjacent crest—if the predetermined path were followed such that multiple crests were provided). In other words, the first and second radial thread profiles  292 ,  294  of the first engagement joint  290  may define a first thread pitch, and the first and second radial thread profile  292 ,  294  of the second engagement joint  290  may define a second thread pitch that is not equal the first thread pitch. For instance, the second thread pitch may be greater than the first thread pitch. 
     In further additional or alternative embodiments wherein outer diffuser bowl  284  includes an outer upper section  284 A and an outer lower section  284 B, a pair of complementary lips  310 ,  312  may be included on the outer upper section  284 A and the outer lower section  284 B. A lower radial lip  312  may extend outward from outer lower section  284 B (e.g., opposite inner wall surface  288 ), while an upper radial lip  310  extends outward from outer upper section  284 A. In some such embodiments, a complementary groove—notch joint is formed between the lower and upper segments  270 B,  270 A. For instance, the upper radial lip  310  may define an axial groove  314  (e.g., extending along a circumferential direction about the axial direction A) at a bottom surface of the upper radial lip  310 . Similarly, the lower radial lip  312  may define an axial notch  316  at a top surface of the lower radial lip  312 . When assembled, the axial notch  316  may be mated with and received within the axial groove  314  such that relative radial movement between the sections is prevented or restricted. Moreover, the complementary groove—notch joint may seal outer diffuser bowl  284  and prevent fluid from passing between the radial lips  310 ,  312 . 
     Turning especially to  FIGS. 16 and 17 , as noted above, electric motor  242  may include a multi-phase winding set  320  (e.g., sealed within inner diffuser bowl  282 ). Thus, electric motor  242  may be provided as a multi-phase motor, such as a 3-phase motor. Multi-phase winding set  320  may thus include a plurality of phase windings, such as a first phase winding  330 , a second phase winding  332 , and a third phase winding  334 . As shown, each of the windings  330 ,  332 ,  334 , may include a discrete pair of wound bobbins. Specifically a first wound bobbin  340 A and a second wound bobbin  340 B of each winding  330 ,  332 , or  334  are provided. When assembled, the first and second wound bobbins  340 A,  340 B may be circumferentially spaced apart from each other (e.g., at opposite radial ends). Additionally or alternatively, each phase winding  330 ,  332 ,  334  may be circumferentially spaced apart from each other such that none of the bobbins  340 A,  340 B are in direct contact. Nonetheless, each phase winding  330 ,  332 ,  334  may be electrically connected to each other in electrical series. 
     When assembled, multi-phase winding set  320  includes a first terminal  342  and a second terminal  344  joined at opposite ends to power line  326  (e.g., the singular, sole power line  326 ). Each phase winding may be electrically connected between first terminal  342  and second terminal  344 . Specifically, each phase winding (e.g., windings  330 ,  332 ,  334 ) is connected in series with each other. A connecting wire may thus extend between adjacent windings or wound bobbins, as would be understood. 
     In certain embodiments, one or more thermal cutouts (TCOs) (e.g.,  350 ,  352 ,  354 ) are mounted within chamber pump housing  234  (e.g., within inner diffuser bowl  282 ) and further sealed within overmolded insulation  324 . For instance, prior to sealing multi-phase winding set  320  within overmolded insulation  324 , the TCO(s) may be electrically connected between first terminal  342  and second terminal  344 . One or more TCOs may, in turn, be connected in electrical series with the multi-phase winding set  320 . In optional embodiments, a distinct TCO  350 ,  352 , or  354  corresponds to a discrete phase winding  330 ,  332 , or  334 . For instance, a first TCO  350  may correspond to first phase winding  330 , a second TCO  352  may correspond to second phase winding  332 , and a third TCO  354  may correspond to third phase winding  334 . 
     Each TCO (e.g., TCOs  350 ,  352 ,  354 ) may be electrically connected in series with its corresponding phase winding (e.g., windings  330 ,  332 ,  334 ). Specifically, each TCO may form the electrical path between adjacent phase windings. As is understood, each TCO may be configured to selectively open the electrical path therethrough in response to detecting a setpoint temperature. Thus, in response to a TCO detecting a temperature within chamber pump housing  234  that is equal to or above the setpoint temperature, the TCO may open, breaking the electrical circuit through multi-phase winding set  320  (e.g., at the corresponding phase winding) and preventing operation of electric motor  242 . 
     The setpoint temperature may generally be set according to the acceptable or desired maximum operating temperature of electric motor  242 . In some embodiments, the setpoint temperature of one or more TCO (e.g., TCO  350 ,  352 ,  354 ) may be greater than or equal to 100° Celsius (e.g., between 100° Celsius and 120° Celsius). For instance, the setpoint temperature may be 110° Celsius. Optionally, each TCO may have a common setpoint temperature. 
     As noted above, the TCOs (e.g., TCOs  350 ,  352 ,  354 ) may be sealed within the overmolded insulation  324 . Generally, the TCOs are positioned in close proximity or contact with one or more portions of multi-phase winding set  320 . In some embodiments, TCOs are mounted on one or more bobbins (e.g., on the portion of wire wound about the corresponding bobbin) to advantageously detect a temperature at a corresponding bobbin. As an example, first TCO  350  may be mounted on the first wound bobbin  340 A of first phase winding  330 . As an additional or alternative example, second TCO  352  may be mounted on the first wound bobbin  340 A of second phase winding  332 . As another additional or alternative example, third TCO  354  may be mounted on the first wound bobbin  340 A of third phase winding  334 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.