Patent Publication Number: US-9839339-B2

Title: Fluid circulation system for dishwasher appliances

Description:
FIELD OF THE INVENTION 
     The subject matter of the present disclosure relates generally to dishwasher appliances, and more particularly to fluid circulation systems with improved filtration in dishwasher appliances. 
     BACKGROUND OF THE INVENTION 
     Dishwasher appliances generally include a tub that defines a wash compartment. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Spray assemblies within the wash chamber can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. Multiple spray assemblies can be provided including e.g., a lower spray arm assembly mounted to the tub at a bottom of the wash chamber, a mid-level spray arm assembly mounted to one of the rack assemblies, and/or an upper spray assembly mounted to the tub at a top of the wash chamber. Other configurations may be used as well. 
     Dishwasher appliances further typically include a fluid circulation system which is in fluid communication with the spray assemblies for circulating fluid to the spray assemblies. The fluid circulation system generally receives fluid from the wash chamber, filters soil from the fluid, and flows the filtered fluid to the spray assemblies. Additionally, unfiltered fluid can be flowed to a drain as required. 
     Currently known fluid circulation systems utilize a large, flat, coarse filter and a cylindrical fine filter to filter soil. Each of these filters typically has constant filter hole, or perforation, sizes which are vulnerable to clogging during operation of the dishwasher appliance. Further, the constant filter hole sizes cannot respond to differences in soil conditions during operation. 
     Accordingly, improved fluid circulation systems for dishwasher appliances are desired. In particular, fluid circulation systems which provide improved fluid filtering would be advantageous. 
     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 accordance with one embodiment, a fluid circulation system for a dishwasher appliance is provided. The dishwasher appliance includes a tub that defines a wash chamber. The fluid circulation system includes a sump for receiving fluid from the wash chamber, the sump comprising a chamber having a sidewall and a base wall. The fluid circulation system further includes a pump, the pump including an impeller disposed within the chamber. The fluid circulation system further includes a filter disposed within the chamber and surrounding the impeller, the filter including a sidewall, the sidewall defining a plurality of perforations extending therethrough. A volume within the filter is greater than a volume between the sidewall of the chamber and the sidewall of the filter for a given height from the base wall. 
     In accordance with another embodiment, a fluid circulation system for a dishwasher appliance is provided. The dishwasher appliance includes a tub that defines a wash chamber. The fluid circulation system includes a sump for receiving fluid from the wash chamber, the sump comprising a chamber having a sidewall and a base wall. The fluid circulation system further includes a pump, the pump including an impeller disposed within the chamber. The fluid circulation system further includes a filter disposed within the chamber and surrounding the impeller, the filter including a sidewall, the sidewall defining a plurality of perforations extending therethrough. Volumes of the plurality of perforations increase along a height from the base wall. 
     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, in which: 
         FIG. 1  provides a front view of an exemplary embodiment of a dishwasher appliance of the present disclosure. 
         FIG. 2  provides a side, cross-sectional view of the exemplary dishwasher appliance of  FIG. 1 . 
         FIG. 3  provides a side, cross-sectional view of a fluid circulation system for a dishwasher appliance during a low soil condition in accordance with one embodiment of the present disclosure; 
         FIG. 4  provides a side, cross-sectional view of a fluid circulation system for a dishwasher appliance during a high soil condition in accordance with one embodiment of the present disclosure; 
         FIG. 5  provides a side, cross-sectional view of a fluid circulation system for a dishwasher appliance during a low soil condition in accordance with another embodiment of the present disclosure; 
         FIG. 6  provides a top, cross-sectional view of a fluid circulation system for a dishwasher appliance in accordance with another embodiment of the present disclosure; and 
         FIG. 7  provides a side, cross-sectional view of a fluid circulation system for a dishwasher appliance during a low soil condition in accordance with yet another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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 or spirit 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 “article” may refer to, but need not be limited to, dishes, pots, pans, silverware, and other cooking utensils and items that can be cleaned in a dishwashing appliance. The term “wash cycle” is intended to refer to one or more periods of time during the cleaning process where a dishwashing appliance operates while containing articles to be washed and uses a detergent and water, preferably with agitation, to e.g., remove soil particles including food and other undesirable elements from the articles. The term “rinse cycle” is intended to refer to one or more periods of time during the cleaning process in which the dishwashing appliance operates to remove residual soil, detergents, and other undesirable elements that were retained by the articles after completion of the wash cycle. The term “drying cycle” is intended to refer to one or more periods of time in which the dishwashing appliance is operated to dry the articles by removing fluids from the wash chamber. The term “fluid” refers to a liquid used for washing and/or rinsing the articles and is typically made up of water that may include additives such as e.g., detergent or other treatments. 
       FIGS. 1 and 2  depict an exemplary domestic dishwasher appliance  100  that may be configured in accordance with aspects of the present disclosure. For the particular embodiment of  FIGS. 1 and 2 , the dishwasher appliance  100  includes a cabinet  102  having a tub  104  therein that defines a wash chamber  106 . As shown, the dishwasher appliance  100  (such as the cabinet  102  thereof) defines a vertical direction V, a lateral direction L, and a transverse direction T, which are mutually orthogonal and define a coordinate system for the dishwasher appliance. The tub  104  includes a front opening (not shown) and a door  120  hinged at its bottom  122  for movement between a normally closed vertical position (shown in  FIGS. 1 and 2 ), wherein the wash chamber  106  is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from the dishwasher. A latch  156  may be used to lock and unlock door  120  for access to chamber  106 . 
     Upper and lower guide rails  124 ,  126  are mounted on tub side walls  128  and accommodate roller-equipped rack assemblies  130  and  132 . Each of the rack assemblies  130 ,  132  is fabricated into lattice structures including a plurality of elongated members  134  (for clarity of illustration, not all elongated members making up assemblies  130  and  132  are shown in  FIG. 2 ). Each rack  130 ,  132  is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber  106 , and a retracted position (shown in  FIGS. 1 and 2 ) in which the rack is located inside the wash chamber  106 . This is facilitated by rollers  135  and  139 , for example, mounted onto racks  130  and  132 , respectively. 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 ,  132 . 
     The dishwasher appliance  100  further includes a lower spray-arm assembly  144  that is rotatably mounted within a lower region  146  of the wash chamber  106  and above a bottom wall  142  of the tub  104  so as to rotate in relatively close proximity to rack assembly  132 . A mid-level spray-arm assembly  148  is located in an upper region of the wash chamber  106  and may be located in close proximity to upper rack  130 . Additionally, an upper spray assembly  150  may be located above the upper rack  130 . 
     Each spray arm-assembly  144  may include a spray arm and a conduit in fluid communication with the spray arm, for providing a fluid flow to the spray arm. For example, mid-level spray-arm assembly  148  may include a spray arm  160  and a conduit  162 . Lower spray-arm assembly  144  may include a spray arm  164  and a conduit  166 . Additionally, upper spray assembly  150  may include a spray head  170  and a conduit  172  in fluid communication with the spray head  170 . 
     The lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly  150  are part of a fluid circulation system  152  for circulating fluid in the dishwasher appliance  100 . The fluid circulation system  152  also includes various components for receiving fluid from the wash chamber  106 , filtering the fluid, and flowing the fluid to the various spray assemblies such as the lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly  150 . As discussed herein such components can be generally positioned within a machinery compartment  140  below the bottom wall  142  and in communication with the wash chamber  106 . 
     The dishwasher appliance  100  is further equipped with a controller  137  to regulate operation of the dishwasher appliance  100 . The controller may include one or more memory devices and one or more microprocessors, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a cleaning cycle. 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. 
     The controller  137  may be positioned in a variety of locations throughout dishwasher appliance  100 . In the illustrated embodiment, the controller  137  may be located within a control panel area  121  of door  120  as shown in  FIGS. 1 and 2 . In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of dishwasher  100  along wiring harnesses that may be routed through the bottom  122  of door  120 . Typically, the controller  137  includes a user interface panel/controls  136  through which a user may select various operational features and modes and monitor progress of the dishwasher  100 . In one embodiment, the user interface  136  may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the 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. The user interface  136  may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface  136  may be in communication with the controller  137  via one or more signal lines or shared communication busses. 
     It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher. The exemplary embodiment depicted in  FIGS. 1 and 2  is for illustrative purposes only. For example, different locations may be provided for user interface  136 , different configurations may be provided for racks  130 ,  132 , different combinations of spray assemblies may be utilized, and other differences may be applied as well. 
     Referring now to  FIGS. 3 through 7 , various embodiments of portions of the fluid circulation system  152  of a dishwasher appliance  100  are illustrated. As shown, system  152  may include, for example, a sump  200  for receiving fluid from the wash chamber  106 . The sump  200  may be mounted to the bottom wall  142  and extend into the machinery compartment  140 , and fluid may for example flow from the bottom wall  142  into the sump  200 . 
     Sump  200  may include, for example, a chamber  202  which receives the fluid from the wash chamber  106 . Sump  200  may additionally include a receptacle  204  which may, for example, receive the fluid from the wash chamber  106  and flow this fluid to the chamber  202 . Receptacle  204  and chamber  202  may be integral portions of a single sump  200  component, or may be separate portions that are connected to form the sump  200 . The receptacle  204  may thus be an upper receptacle positioned above the lower chamber  202  along the vertical direction V. Receptacle may have a generally conical or funnel shape which directs the fluid flow towards and into the chamber  202 , or may have any other suitable shape. 
     As illustrated, chamber  202  may include a sidewall  206  and a base wall  208 . The sidewall  206  may extend from the base wall  208 . In some embodiments, the sidewall  206  may have a generally circular cross-sectional shape, as illustrated in  FIG. 6 . Alternatively, the sidewall  206  may have a generally rectangular or other suitable polygonal cross-sectional shape, with multiple linear or curvilinear cross-sectional portions. 
     System  152  may further include a pump  210 . Pump  210  may include an impeller  212  which is disposed within the chamber  202 . Pump  210  may further include a motor  214  and a shaft  216  which connects the motor  214  and impeller  212 . As illustrated, the shaft  216  may extend through the base wall  208 , and the motor  214  may be external to the chamber  202 . Alternatively, the motor  214  may be disposed within the chamber  202 , and may for example be hermetically sealed to prevent damage thereto from fluids within the chamber  202 . Impeller  212  may spin within the chamber  202  when activated by the motor  214  to influence the flow of fluid within the chamber  202 . Pump  210  may further include a diffuser  218 . Diffuser  218  may receive fluid influenced by the impeller  212 . Fluid may thus flow through the diffuser  218  and exit the pump  210  through the diffuser  218 . 
     System  152  may further include an outlet conduit  220 . The outlet conduit  220  flows fluid from the sump  200 , such as from the chamber  202  thereof, to the wash chamber  106 . For example, outlet conduit  220  may be connected to and in fluid communication with the various spray assemblies, such as the lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly  150 , such that fluid flowed into the outlet conduit  220  can flow to these spray assemblies. Valves (not shown) disposed within the outlet conduit  220  or other conduits in the system  152  may selectively direct the flow of fluid from the outlet conduit  220  as required. Outlet conduit  220  may further be connected to and in fluid communication with the diffuser  218 . Accordingly, fluid drawn into the diffuser  218  from the impeller  212  may flow from the diffuser  218  into the outlet conduit  220  towards, for example, the spray assemblies, drain assembly, etc. 
     As illustrated in  FIGS. 3 through 7 , a filter  250  is disposed within the chamber  202 . As shown, the filter  250  surrounds the impeller  212 , and can additionally surround at least a portion of the diffuser  218  as well as other components of the pump  210 . Filters  250  and the configuration of filters  250  within chambers  202  in accordance with the present disclosure advantageously provide numerous advantages to the dishwasher appliance  100 . In particular, fluid circulation systems  152  which include such components and configurations provide improved fluid filtering. Filters  250  and the configurations within chambers  250  advantageously respond to differences in soil conditions during operation, thus reducing the risk of clogging and providing more efficient filtering. Additionally, such filters  250  are advantageously passive filters, with no active elements such as cleaning jets, thus reducing the energy requirements and cost associated with such efficient filtering. 
     As illustrated, a filter  250  in accordance with the present disclosure may include a sidewall  252 . Filter  250  may further include a top wall  254 , through which the outlet conduit  220  extends. Still further, filter  250  may include a base wall (not shown) that contacts the base wall  208  of the chamber  202 , or the sidewall  252  may contact the base wall  208 . The sidewall  252  may extend from the top wall  254  or between the top wall  254  and bottom wall. In some embodiments, the sidewall  252  may have a generally circular cross-sectional shape, as illustrated in  FIG. 6 . Alternatively, the sidewall  252  may have a generally rectangular or other suitable polygonal cross-sectional shape, with multiple linear or curvilinear cross-sectional portions. 
     As further illustrated, the sidewall  252 , as well as the top wall  254  and bottom wall, may define a plurality of perforations  256  extending therethrough. The perforations  256  may, as discussed herein, be sized and shaped to allow fluid flow therethrough, while preventing the flow of soil therethrough, thus filtering the fluid as it flows into the filter  250  through the walls thereof. Each perforation  256  may have any suitable shape, such as a generally circular cross-sectional shape, a generally rectangular cross-sectional shape, or other suitable polygonal cross-sectional shape. In the embodiments shown, the perforations are assumed to have circular cross-sectional shapes and thus be cylindrical. 
     In some exemplary embodiments, as shown, a volume within the filter  250  is greater than a volume between the sidewall  206  of the chamber  202  and the sidewall  252  of the filter  250  for a given height  260  from the base wall  208 . In other words, at any given height  260  from the base wall  208  (through which the sidewall  206  and sidewall  252  extend), the volume within the filter  250  is greater than the volume without the filter  250  (between the filter sidewall  252  and chamber sidewall  206 ). Advantageously, such arrangement allows the filter  250  to respond to differences in soil conditions in order to reducing clogging thereof. For example,  FIGS. 3, 5 and 7  illustrate fluid flowing into filter  250 , with the fluid having a low soil condition. In a low soil condition, the amount and/or size of soil particles is generally less relative to a high soil condition. Due to the disparity in volumes inside and outside of the filter  250 , the height  262  (from base wall  208 ) of the fluid level outside of the filter  250  is greater than the height  264  (from base wall  208 ) of the fluid level inside of the filter  250 . However, this disparity in heights  262 ,  264  is relatively minimal. In any event, the greater height  262  allows fluid to access additional, higher perforations in the sidewall  252 , thus providing improved filtering and reducing clogging. 
       FIG. 4  illustrates fluid flowing into filter  250 , with the fluid having a high soil condition. In a high soil condition, the amount and/or size of soil particles is generally greater relative to a low soil condition. Due to the disparity in volumes inside and outside of the filter  250 , the height  262  (from base wall  208 ) of the fluid level outside of the filter  250  is greater than the height  264  (from base wall  208 ) of the fluid level inside of the filter  250 . Further, this disparity in heights  262 ,  264  is greater than the disparity during a low soil condition. The greater height  262  and increased disparity in heights  262 ,  264  allows fluid to access even more additional, higher perforations in the sidewall  252 , thus providing improved filtering and reducing clogging. The disparity in volumes thus allows the passive filter  250  to respond to varying soil conditions, by facilitating disparities in heights during high soil conditions versus low soil conditions to allow additional access to perforations  256  as required, thus providing improved filtering and reducing clogging. 
     In some embodiments, as illustrated in  FIGS. 3 through 5 , the sidewall  206  of the chamber  202  extends from the base wall  208  along the vertical direction V. The sidewall  252  of the filter  250  may additionally extend along the vertical direction V. The sidewalls  206 ,  252  in these or other embodiments may thus be generally parallel. 
     In other embodiments, as illustrated in  FIG. 7 , at least a portion of the inner surface  207  of the sidewall  206  of the chamber  202  extends from the base wall  208  at an angle to the vertical direction V. As illustrated, the portion of the inner surface  207  may extend from the base wall  208  inward towards the filter  250 , such as towards the sidewall  252 . The sidewall  252  of the filter  250  may extend along the vertical direction V. At least portions of the sidewalls  206 ,  252  in these or other embodiments may thus not be parallel. In embodiments wherein a portion of the inner surface  207  extends inwards towards the filter  250 , this facilitate a faster increase in the disparity between the heights  262 ,  264  as the soil condition and fluid height increases, by reducing the outer volume as the height  260  increases. 
     In additional or alternative embodiments, the perforations  256  may advantageously be configured to facilitate improved filtration and reduced clogging. For example, and referring to  FIGS. 3 through 5 and 7 , the volumes of the perforations  256  may increase along the height  260  from the base wall  208 . In other words, as the height  260  increases, the volumes of the individual perforations  256  may increase. The increase in volumes in correspondence with increasing height  260  may be advantageous for further reducing clogging and improving filtration. For example, as discussed above, higher soil conditions result in increased heights  262  of fluid outside of the filter  250 . Fluid at higher heights  262 , however, can advantageously flow easier through the larger volume perforations  256 , with larger soil particles still being filtered by such perforations  256 . Accordingly, the risks of clogging during high soil conditions can advantageously be minimized, and filtration thus improved. 
     In some embodiments, as illustrated in  FIGS. 3, 4 and 7 , the increase in volume of the perforations  256  may be step-wise. In a step-wise increase, a number of rows of perforation  256  and/or perforations  256  in a given height range have generally identical volumes. A neighboring number of rows of perforation  256  and/or perforations  256  in a next height range have generally identical volumes which are greater than the first, and so on. In other embodiments, as illustrated in  FIG. 5 , the increase in volume of the perforations  256  may be continuous. In a continuous increase, each perforation  256  is greater in volume than the perforation directly below it along the height  260  and less in volume than the perforation directly above it along the height  260 . The perforations  256  can be arranged in rows, with each row of perforations  256  increasing in volume relative to the row below it along the height  260 . 
     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 language of the claims.