Patent Publication Number: US-2019167066-A1

Title: Dishwasher appliance having a pressure sensor and a tub lip sensor for flood detection

Description:
FIELD OF THE INVENTION 
     The present disclosure relates generally to dishwasher appliances, and more particularly to dishwasher appliances having flood detection and prevention features and methods therefore. 
     BACKGROUND OF THE INVENTION 
     Dishwasher appliances generally include a tub that defines a wash chamber. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Multiple spray assemblies can be positioned within the wash chamber for applying or directing wash fluid towards articles disposed within the rack assemblies in order to clean such articles. Dishwasher appliances are also typically equipped with at least one circulation pump for circulating fluid through the multiple spray assemblies. 
     Under certain conditions, dishwasher appliances are prone to flooding over a tub lip of the tub. For instance, dishwasher appliances may be prone to flooding over the tub lip during an out-of-level condition, an inlet water valve failure, and/or a drain pump failure. When one or more of such conditions occur, the water level can rise above the designed fill level and spill over the tub lip and onto the floor. This may be detrimental to consumers&#39; homes. 
     Certain dishwasher appliances include features for detecting tub overfills or flood events. For example, some conventional dishwasher appliances include float sensors. To detect a flood event, the float sensor floats on top of the water in the tub, and if the float sensors floats upward to a certain height, the float sensor triggers a response indicating a flood event. One challenge with float sensors is that they are typically located proximate the sump area of the tub, and accordingly, such float sensors affect the water flow through the sump area during wash and drain cycles. This may decrease the efficiency and performance of the dishwasher appliance during normal operating conditions. Moreover, some conventional float sensors are located in the manual filter chamber where soiled water collects during a wash cycle. By locating the float sensor in the manual filter chamber, the volume of soiled water that can be collected is limited, which may negatively affect wash performance. Further, other conventional dishwasher appliances include pressure sensors that activate when the water level is excessively high. However, such pressure sensors can be prone to nuisance or inadvertent tripping and typically allow for little time for the dishwasher appliance to take corrective action to prevent a flood event. 
     Accordingly, dishwasher appliances that include flood prevention features and methods therefore that address one or more of the challenges noted above would be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present disclosure provides a dishwasher appliance that includes features that allow for prevention and detection of flood events or tub overfills without sacrificing performance or efficiency of the dishwasher appliance. Moreover, methods for detecting and preventing such flood events are also provided. Additional aspects and advantages of the invention will be set forth in part in the following description, may be apparent from the description, or may be learned through practice of the invention. 
     In accordance with one exemplary embodiment, a method for detecting a flood event in a dishwasher appliance is provided. The dishwasher appliance includes a cabinet and a tub positioned within the cabinet. The tub has a tub lip. The dishwasher appliance also includes a pressure sensor, a tub lip sensor, a drain pump, and a circulation pump. The method includes determining whether the circulation pump is activated. The method also includes determining whether a pressure sensor output of the pressure sensor is greater than or equal to a first pressure threshold for a predetermined time if the circulation pump is not activated, or, determining whether the pressure sensor output of the pressure sensor is greater than or equal to a second pressure threshold for a predetermined time if the circulation pump is activated. Further, the method includes determining whether the tub lip sensor has sensed wash fluid at or proximate the tub lip for a predetermined time if the pressure sensor output is not greater than or equal to either the first pressure threshold for the predetermined time or the second pressure threshold for the predetermined time. In addition, the method includes activating the drain pump if the tub lip sensor has sensed wash fluid at or proximate the tub lip for the predetermined time. 
     In accordance with another exemplary embodiment, a dishwasher appliance is provided. The dishwasher appliance includes a cabinet and a tub positioned within the cabinet. The tub defines a wash chamber for receipt of articles for washing. The tub includes a tub lip. The dishwasher appliance also includes a tub lip sensor positioned proximate the tub lip. The dishwasher appliance further includes one or more spray assemblies and a circulation pump for circulating wash fluid to the one or more spray arm assemblies. In addition, the dishwasher appliance includes a drain pump, a sump, and a pressure sensor mounted to the sump. Moreover, the dishwasher appliance includes a controller communicatively coupled with the pressure sensor, the tub lip sensor, the drain pump, and the circulation pump. The controller is configured to: determine whether the circulation pump is activated; determine whether a pressure sensor output of the pressure sensor is greater than or equal to a first pressure threshold for a predetermined time if the circulation pump is not activated, or, determine whether the pressure sensor output of the pressure sensor is greater than or equal to a second pressure threshold for a predetermined time if the circulation pump is activated; determine whether the tub lip sensor has sensed wash fluid at or proximate the tub lip for a predetermined time if the pressure sensor output is not greater than or equal to either the first pressure threshold for the predetermined time or the second pressure threshold for the predetermined time; and activate the drain pump if the controller determines that the tub lip sensor has sensed wash fluid at or proximate the tub lip for the predetermined time. 
     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 perspective view of an exemplary embodiment of a dishwasher appliance of the present disclosure with a door in a partially open position; 
         FIG. 2  provides a side, cross sectional view of the exemplary dishwasher appliance of  FIG. 1 ; 
         FIG. 3  provides a close up, cross sectional view of a sump and a pressure sensor of the dishwasher appliance of  FIGS. 1 and 2 ; 
         FIG. 4  provides a perspective view of an exemplary tub lip sensor coupled with a tub lip of a tub of the dishwasher appliance of  FIGS. 1 and 2 ; and 
         FIGS. 5A and 5B  provide a flow diagram of an exemplary method for detecting a flood event according to exemplary embodiments 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 which a dishwashing appliance operates while containing the 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 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 “drain cycle” is intended to refer to one or more periods of time during which the dishwashing appliance operates to discharge soiled water from the dishwashing appliance. The term “wash fluid” refers to a liquid used for washing and/or rinsing the articles and is typically made up of water that may include other additives such as detergent or other treatments. Furthermore, as used herein, terms of approximation, such as “approximately,” “substantially,” or “about,” refer to being within a ten percent (10%) margin of error. 
       FIGS. 1 and 2  depict an exemplary dishwasher or dishwashing appliance  100  that may be configured in accordance with aspects of the present disclosure. For the particular embodiment of  FIGS. 1 and 2 , dishwasher  100  defines a vertical direction V, a lateral direction L, and a transverse direction T. Each of the vertical direction V, lateral direction L, and transverse direction T are mutually perpendicular to one another and form an orthogonal direction system. Dishwasher  100  includes a cabinet  102  having a tub  104  therein that defines a wash chamber  106 . As shown in  FIG. 2 , tub  104  extends between a top  107  and a bottom  108  along the vertical direction V, between a pair of side walls  110  along the lateral direction L, and between a front side  111  and a rear side  112  along the transverse direction T. 
     Tub  104  includes a front opening  114  ( FIG. 1 ) and a door  116  hinged at its bottom for movement between a normally closed vertical position (shown in  FIG. 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  100 . Dishwasher  100  includes a door closure mechanism or assembly  118  that is used to lock and unlock door  116  for accessing and sealing wash chamber  106 . 
     As further shown in  FIG. 2 , tub side walls  110  accommodate a plurality of rack assemblies. More specifically, guide rails  120  are mounted to side walls  110  for supporting a lower rack assembly  122 , a middle rack assembly  124 , and an upper rack assembly  126 . Upper rack assembly  126  is positioned at a top portion of wash chamber  106  above middle rack assembly  124 , which is positioned above lower rack assembly  122  along the vertical direction V. Each rack assembly  122 ,  124 ,  126  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, for example, by rollers  128  mounted onto rack assemblies  122 ,  124 ,  126 , respectively. Although guide rails  120  and rollers  128  are illustrated herein as facilitating movement of the respective rack assemblies  122 ,  124 ,  126 , it should be appreciated that any suitable sliding mechanism or member may be used according to alternative embodiments. 
     Some or all of the rack assemblies  122 ,  124 ,  126  are fabricated into lattice structures including a plurality of wires or elongated members  130  (for clarity of illustration, not all elongated members making up rack assemblies  122 ,  124 ,  126  are shown in  FIG. 2 ). In this regard, rack assemblies  122 ,  124 ,  126  are generally configured for supporting articles within wash chamber  106  while allowing a flow of wash fluid to reach and impinge on those articles, e.g., during a cleaning or rinsing cycle. According to other exemplary embodiments, a silverware basket (not shown) may be removably attached to a rack assembly, e.g., lower rack assembly  122 , for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by rack  122 . 
     Dishwasher  100  further includes a plurality of spray assemblies for urging a flow of water or wash fluid onto the articles placed within wash chamber  106 . More specifically, as illustrated in  FIG. 2 , dishwasher  100  includes a lower spray arm assembly  134  disposed in a lower region  136  of wash chamber  106  and above a sump  138  so as to rotate in relatively close proximity to lower rack assembly  122 . Similarly, a mid-level spray arm assembly  140  is located in an upper region of wash chamber  106  and may be located below and in close proximity to middle rack assembly  124 . In this regard, mid-level spray arm assembly  140  is generally configured for urging a flow of wash fluid up through middle rack assembly  124  and upper rack assembly  126 . Additionally, an upper spray assembly  142  may be located above upper rack assembly  126  along the vertical direction V. In this manner, upper spray assembly  142  may be configured for urging and/or cascading a flow of wash fluid downward over rack assemblies  122 ,  124 , and  126 . As further illustrated in FIG.  2 , upper rack assembly  126  may further define an integral spray manifold  144 , which is generally configured for urging a flow of wash fluid substantially upward along the vertical direction V through upper rack assembly  126 . 
     The various spray assemblies and manifolds described herein may be part of a fluid distribution system or fluid circulation assembly  150  for circulating water and wash fluid in tub  104 . More specifically, fluid circulation assembly  150  includes a circulation pump  152  for circulating water and wash fluid (e.g., detergent, water, and/or rinse aid) in tub  104 . Circulation pump  152  is located within sump  138  or within a machinery compartment located below sump  138  of tub  104 . Circulation pump  152  is in fluid communication with an external water supply line (not shown) and sump  138 . A water inlet valve  153  can be positioned between the external water supply line and circulation pump  152  to selectively allow water to flow from the external water supply line to circulation pump  152 . Additionally or alternatively, water inlet valve  153  can be positioned between the external water supply line and sump  138  to selectively allow water to flow from the external water supply line to sump  138 . Water inlet valve  153  can be selectively controlled to open to allow the flow of water into dishwasher  100  and can be selectively controlled to cease the flow of water into dishwasher  100 . Further, fluid circulation assembly  150  may include one or more fluid conduits or circulation piping for directing water and/or wash fluid from circulation pump  152  to the various spray assemblies and manifolds. For example, for the embodiment depicted in  FIG. 2 , a primary supply conduit  154  extends from circulation pump  152 , along rear  112  of tub  104  along the vertical direction V to supply wash fluid throughout wash chamber  106 . 
     As further illustrated in  FIG. 2 , primary supply conduit  154  is used to supply wash fluid to one or more spray assemblies, e.g., to mid-level spray arm assembly  140  and upper spray assembly  142 . However, it should be appreciated that according to alternative embodiments, any other suitable plumbing configuration may be used to supply wash fluid throughout the various spray manifolds and assemblies described herein. For example, according to another exemplary embodiment, primary supply conduit  154  could be used to provide wash fluid to mid-level spray arm assembly  140  and a dedicated secondary supply conduit (not shown) could be utilized to provide wash fluid to upper spray assembly  142 . Other plumbing configurations may be used for providing wash fluid to the various spray devices and manifolds at any location within dishwasher appliance  100 . 
     Each spray arm assembly  134 ,  140 ,  142 , integral spray manifold  144 , or other spray device may include an arrangement of discharge ports or orifices for directing wash fluid received from circulation pump  152  onto dishes or other articles located in wash chamber  106 . The arrangement of the discharge ports, also referred to as jets, apertures, or orifices, may provide a rotational force by virtue of wash fluid flowing through the discharge ports. Alternatively, spray arm assemblies  134 ,  140 ,  142  may be motor-driven, or may operate using any other suitable drive mechanism. Spray manifolds and assemblies may also be stationary. The resultant movement of the spray arm assemblies  134 ,  140 ,  142  and the spray from fixed manifolds provides coverage of dishes and other dishwasher contents with a washing spray. Other configurations of spray assemblies may be used as well. For example, dishwasher  100  may have additional spray assemblies for cleaning silverware, for scouring casserole dishes, for spraying pots and pans, for cleaning bottles, etc. 
     In operation, circulation pump  152  draws wash fluid in from sump  138  and pumps it to a diverter  156 , e.g., which is positioned within sump  138  of dishwasher appliance. Diverter  156  may include a diverter disk (not shown) disposed within a diverter chamber  158  for selectively distributing the wash fluid to the spray arm assemblies  134 ,  140 ,  142  and/or other spray manifolds or devices. For example, the diverter disk may have a plurality of apertures that are configured to align with one or more outlet ports (not shown) at the top of diverter chamber  158 . In this manner, the diverter disk may be selectively rotated to provide wash fluid to the desired spray device. 
     According to an exemplary embodiment, diverter  156  is configured for selectively distributing the flow of wash fluid from circulation pump  152  to various fluid supply conduits, only some of which are illustrated in  FIG. 2  for clarity. More specifically, diverter  156  may include four outlet ports (not shown) for supplying wash fluid to a first conduit for rotating lower spray arm assembly  134  in the clockwise direction, a second conduit for rotating lower spray arm assembly  134  in the counter-clockwise direction, a third conduit for spraying an auxiliary rack such as the silverware rack, and a fourth conduit for supply mid-level and/or upper spray assemblies  140 ,  142 , e.g., such as primary supply conduit  154 . 
     Drainage of soiled water within sump  138  may occur, for example, through drain assembly  166 . In particular, water may exit sump through a drain and may flow through a drain conduit  167 . A drain pump  168  may facilitate drainage of the soiled water by pumping the water to a drain line external to the dishwasher  100 . 
     Dishwasher  100  is further equipped with a controller  160  to regulate operation of dishwasher  100 . Controller  160  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 some embodiments, 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  160  may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/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  160  may be positioned in a variety of locations throughout dishwasher  100 . In the illustrated embodiment, controller  160  may be located within a control panel area  162  of door  116  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 of door  116 . Typically, the controller  160  includes a user interface panel/controls  164  through which a user may select various operational features and modes and monitor progress of dishwasher  100 . In one embodiment, the user interface  164  may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the user interface  164  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  164  may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface  164  may be in communication with the controller  160  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  100 . The exemplary embodiment depicted in  FIGS. 1 and 2  is for illustrative purposes only. For example, different locations may be provided for user interface  164 , different configurations may be provided for rack assemblies  122 ,  124 ,  126 , different spray arm assemblies  134 ,  140 ,  142  and spray manifold configurations may be used, and other differences may be applied while remaining within the scope of the present subject matter. 
     With reference still to  FIG. 2 , in some instances, tub  104  of dishwasher  100  may experience a tub overfill or flood event, e.g., when wash fluid floods over a tub lip  170  of tub  104 . Such an overfill or flood event can occur as a result of any number of conditions, such as e.g., an out-of-level condition, an inlet water valve failure, and/or a drain pump failure. Accordingly, in accordance with exemplary aspects of the present disclosure, dishwasher  100  may utilize outputs from a pressure sensor  200  and feedback from a tub lip sensor  202  to detect and/or prevent flood events. 
       FIG. 3  provides a close up, cross sectional view of sump  138  and pressure sensor  200  mounted thereto of the dishwasher  100  of  FIGS. 1 and 2 . Pressure sensor  200  is operatively configured to detect a liquid level L within sump  138  and then communicate the liquid level L to controller  160  via one or more signals. Thus, pressure sensor  200  and controller  160  are communicatively coupled. The pressure sensor  200  can send signals to controller  160  as a frequency, as an analog signal, or in another suitable manner. Pressure sensor  200  can be any suitable type of sensor capable of sensing the liquid level L within dishwasher  100 . 
     For the depicted embodiment of  FIG. 3 , pressure sensor  200  is configured to sense the height H of the water above pressure sensor  200  along the vertical direction V, e.g., by measuring the pressure on pressure sensor  200 . In particular, for this embodiment, pressure sensor  200  includes a pressure plate that is acted on by the pressure of the wash fluid within sump  138 . As the liquid level L rises, the pressure plate is pushed upward along the vertical direction V and thus compresses air trapped within the housing and a diaphragm of pressure sensor  200 , which causes the diaphragm to flex or alter its position. As a result of the pressure and consequent movement of the diaphragm, a permanent magnet attached to the diaphragm may change its position in relation to a Hall-effect transducer. The transducer delivers one or more electrical signals proportional to the magnetic field of the magnet. The signals may be linearized, digitized, and/or amplified before being sent to controller  160  for processing. The pressure sensor may include a printed circuit board (PCB) board to electrically connect the various electrical components. As noted above, other types of pressure sensors  200  are contemplated. 
       FIG. 4  provides a perspective view of tub lip sensor  202  coupled with or attached to tub lip  170  of tub  104  of the dishwasher appliance  100  of  FIGS. 1 and 2 . Tub lip sensor  202  is operatively configured to detect high water or wash fluid levels within tub  104 , and more particularly, tub lip sensor  202  is configured to sense wash fluid that is at or proximate tub lip  170 . In this way, appropriate action can be taken to prevent an overfill or flood event. 
     Notably, for the depicted embodiment of  FIG. 4 , tub lip sensor  202  is positioned on or mounted to tub lip  170  of tub  104 , and more particularly, tub lip sensor  202  is positioned on or mounted to tub lip  170  at front side  111  of tub  104  for this embodiment. By positioning tub lip sensor  202  at or on tub lip  170 , tub lip sensor  202  does not interfere with the water flow through sump  138  during wash or drain cycles and takes up a minimal amount of space, e.g., compared to float sensors. In addition, by placing tub lip sensor  202  at front side  111  of tub  104 , tub lip sensor  202  is advantageously positioned to detect water spillage or floods over the front portion of tub  104 , which is a location where water is likely to spill or flood onto the floor of a consumer&#39;s home in the event of a water breach over this portion of tub  104 . Further, for this embodiment, tub lip sensor  202  is positioned approximately along a lateral centerline LC that extends along the transverse direction T midway along the lateral length of tub  104 . In this way, tub lip sensor  170  may still detect high wash fluid levels during out-of-level conditions, e.g., tilting of the dishwasher  100  about the transverse direction T. 
     In the depicted embodiment of  FIG. 4 , tub lip sensor  202  is a conductivity sensor. That is, when water or wash fluid fills up to tub lip  170 , the wash fluid bridges leads or electrical contacts of tub lip sensor  202 , thus allowing an electrical current to travel from one lead to the other. This completes a circuit that includes the electrical leads of tub lip sensor  202  and controller  160 , among other possible electrical components. The change or increase in electrical current through the circuit is indicative that wash fluid is present or sensed at tub lip  170 . The change in electrical current through the circuit can be measured by any suitable parameter (e.g., a change in current, voltage, or resistance) and by any suitable device (e.g., a multimeter positioned within controller  160 ). 
       FIGS. 5A and 5B  provide a flow diagram of an exemplary method ( 300 ) for detecting and/or preventing a flood event of a dishwasher appliance according to exemplary embodiments of the present disclosure. For instance, the method ( 300 ) can be used to detect and/or prevent floods of the dishwasher appliance  100  of  FIGS. 1 through 4 . Further, as will be explained below, outputs of the pressure sensor  200  of  FIGS. 2 and 3  and the tub lip sensor  202  of  FIGS. 2 and 4  can be utilized to detect and prevent flood events of dishwasher  100 . To provide context to exemplary method ( 300 ), the reference numerals used in  FIGS. 1 through 4  to describe the features of dishwasher  100  will be used below. It will be appreciated, however, that method ( 300 ) is not limited in scope to dishwasher  100  of  FIGS. 1 through 4 ; rather, method ( 300 ) is applicable to other suitable types and models of dishwashers. 
     At ( 302 ), method ( 300 ) includes powering up or operating a dishwasher. For instance, dishwasher  100  can be powered in a standby mode (e.g., power is supplied to dishwasher  100  but dishwasher is not performing a cycle). Moreover, dishwasher  100  can be operated in a given cycle, including for example, a fill cycle, a circulation cycle, a drain cycle, or a dry cycle. So long as power is supplied to dishwasher  100 , method ( 300 ) commences. 
     In some implementations, when method ( 300 ) commences at ( 302 ), controller  160  receives a pressure sensor output indicative of the liquid level L within sump  138 . For instance, for this implementation, controller  160  receives a signal from pressure sensor  200  indicative of the height H of the wash fluid above pressure sensor  200 , which is in turn indicative of the liquid level L within sump  138 . Controller  160  can receive the pressure sensor output directly or indirectly from pressure sensor  200 . Preferably, controller  160  receives pressure sensor outputs continuously at a predetermined interval, such as e.g., every tenth of a second, every half second, every second, etc. In this way, dishwasher  100  constantly monitors for flood events. 
     At ( 304 ), method ( 300 ) includes determining whether the circulation pump is activated. Stated differently, method ( 300 ) includes determining whether wash fluid is being circulated about or through dishwasher  100 . As one example, to determine whether circulation pump  152  is activated, controller  160  can receive one or more signals from circulation pump  152  indicating that circulation pump  152  is activated. As another example, controller  160  can be configured to control circulation pump  152  and logic within controller  160  can be used to determine whether circulation pump  152  is activated. Determining whether circulation pump  152  is activated can be determined in other suitable manners as well. 
     Notably, for this embodiment, determining whether circulation pump  152  is active will determine which pressure threshold will be compared against the pressure sensor output received by controller  160 . That is, whether the circulation pump  152  is activated determines whether the pressure sensor output is compared to a first pressure threshold P 1  at ( 306 ) or a second pressure threshold P 2  at ( 308 ). If the circulation pump is not activated as determined at ( 304 ) (i.e., there is no wash fluid being circulated through dishwasher  100 ), most or at least a majority of the wash fluid is held in sump  138 . If the circulation pump is activated as determined at ( 304 ) (i.e., circulation pump  152  is circulating water and wash fluid through dishwasher  100 ), the liquid level L within sump  138  is expected to be lower as some of the wash fluid is actively being dispersed by one or more of the spray arm assemblies  134 ,  140 ,  142 . Thus, there is less wash fluid in sump  138  when circulation pump  152  is active compared to when the circulation pump  152  is not active. As such, there are different pressure thresholds depending on whether circulation pump  152  is activated, and for this embodiment, the first pressure threshold P 1  is a greater than the second pressure threshold P 2 . 
     At ( 306 ), if the circulation pump is not activated as determined at ( 304 ), then method ( 300 ) includes determining whether a pressure sensor output of the pressure sensor is greater than or equal to a first pressure threshold for a predetermined time. That is, at ( 306 ) it is determined whether the pressure sensor output received by controller  160  is greater than or equal to the first pressure threshold P 1  for a predetermined time. The predetermined time can be, for example, between about three (3) and five (5) seconds. Preferably, in some implementations, in determining whether the pressure sensor output of pressure sensor  200  is greater than or equal to the first pressure threshold P 1  for the predetermined time, the pressure sensor output must be consecutively greater than or equal to the first pressure threshold P 1  for the predetermined time. In this way, it is less probable or likely that pressure sensor  200  has been inadvertently or nuisance tripped. 
     If at ( 306 ) it is determined that the pressure sensor output is not greater than or equal to the first pressure threshold P 1 , then the controller logic proceeds to ( 320 ) to check to see if wash fluid is present at the tub lip, as will be explained in greater detail below. In this way, in the event pressure sensor  200  fails or otherwise fails to correctly output the pressure sensor output indicative of the liquid level L within dishwasher  100 , dishwasher  100  may still detect and/or prevent flood events. If, however, at ( 306 ) it is determined that the pressure sensor output is greater than or equal to the first pressure threshold P 1 , then it is determined that there is presently a flood event or about to be a flood event in dishwasher  100 . As such, the controller logic proceeds to ( 310 ). 
     At ( 308 ), if the circulation pump is activated as determined at ( 304 ), then method ( 300 ) includes determining whether the pressure sensor output of the pressure sensor is greater than or equal to a second pressure threshold for a predetermined time. That is, at ( 308 ) it is determined whether the pressure sensor output received by controller  160  is greater than or equal to the second pressure threshold P 2  for a predetermined time. The predetermined time can be between about three (3) and five (5) seconds, for example. In some implementations, in determining whether the pressure sensor output of pressure sensor  200  is greater than or equal to the second pressure threshold P 2  for the predetermined time, the pressure sensor output must be consecutively greater than or equal to the second pressure threshold P 2  for the predetermined time. In this way, it is less probable or likely that pressure sensor  200  has been inadvertently or nuisance tripped. 
     If at ( 308 ) it is determined that the pressure sensor output is not greater than or equal to the second pressure threshold P 2 , then the controller logic proceeds to ( 320 ) to check to see if wash fluid is present at the tub lip. In this manner, in the event pressure sensor  200  fails or otherwise fails to correctly output the pressure sensor output indicative of the liquid level L within dishwasher  100 , dishwasher  100  may still detect and/or prevent flood events. If, however, at ( 308 ) it is determined that the pressure sensor output is greater than or equal to the second pressure threshold P 2 , then it is determined that there is presently a flood event or about to be a flood event in dishwasher  100 . As such, the controller logic proceeds to ( 310 ). 
     At ( 310 ), the method ( 300 ) includes activating the drain pump if the pressure sensor output is greater than or equal to either the first pressure threshold for the predetermined time or the second pressure threshold for the predetermined time. Thus, corrective action in response to the detected flood event can be taken. Preferably, drain pump  168  removes wash fluid from sump  138  and tub  104  at a faster rate than water and/or wash fluid flows into sump  138 . In this manner, drain pump  168  can overcome the flow rate of water inlet valve  153 , particularly if water inlet valve  153  has failed. Further, in some implementations, drain pump  168  removes wash fluid from sump  138  at twice or at least twice the rate of wash fluid entering sump  138 . As one example, drain pump  168  removes fluid from sump  138  at three (3) gallons per minute (gpm) and water inlet valve  153  allows for a flow rate into sump  138  at a flow rate of 0.8 gpm. 
     In some implementations, at ( 310 ), the method ( 300 ) includes starting a timer. The starter can be a component of controller  160  or can be a separate component communicatively coupled with controller  160 , for example. In such implementations, as will be explained below, the timer is started so that if the liquid level L within sump  138  is not below a certain threshold within a predetermined time, the consumer is notified so that corrective action may be taken. Moreover, preferably, the starting of the timer is coordinated with the activation of drain pump  168 . That is, the timer is started upon activation of drain pump  168 . In this way, the activated drain pump  168  does not run indefinitely without the consumer being notified in the event the drain pump  168  simply cannot remove the wash fluid from sump  138 , e.g., due to a water inlet valve failure. This may, for example, improve the service life of drain pump  168 . 
     In implementations where dishwasher  100  is performing a cycle, particularly a rinse or wash cycle, additionally or alternatively to activating drain pump  168 , method ( 300 ) includes cancelling a current cycle of the dishwasher appliance if the pressure sensor output is greater than or equal to either the first pressure threshold P 1  or the second pressure threshold P 2  as determined at ( 306 ) or ( 308 ), respectively. When the pressure sensor output is greater than or equal to either the first pressure threshold P 1  or the second pressure threshold P 2 , controller  160  effectively determines that a flood event has occurred or is on the verge or precipice of a flood event, as noted above. Thus, equipped with such information, dishwasher  100  can take corrective action to potentially prevent the flood event or reduce the potential damage of the flood event. 
     As one example, as noted above, the current cycle being performed by dishwasher appliance  100  can be canceled. For instance, if dishwasher  100  is performing a wash or rinse cycle, to cancel the cycle, the method ( 300 ) can include deactivating water inlet valve  153  (e.g., closing the valve to a closed position (assuming it is still operable)) to prevent further water from entering dishwasher  100 . Moreover, method ( 300 ) can likewise include deactivating circulation pump  152 . In this way, energy can be conserved and will allow the wash fluid to flow back to sump  138  such that it can be removed from dishwasher  100 . 
     In some further implementations, at ( 310 ), the method ( 300 ) includes logging a flood fault. In this way, if dishwasher  100  is serviced, an operator can quickly ascertain why dishwasher  100  was cancelled mid-cycle. Moreover, in some implementations, as shown at ( 310 ), the method ( 300 ) includes notifying a consumer that the cycle has been cancelled and that a flood event or possible flood event has occurred. For instance, as one example, dishwasher  100  may include a speaker that audibly communicates the notification to a consumer. As another example, dishwasher  100  may include a communication interface that is communicatively coupled with controller  160 . The communication interface may include a network interface that provides for communication over a network, such as e.g., a wireless network. In such implementations, dishwasher  100  may send notifications to a consumer&#39;s user device, such as e.g., a cell phone. 
     At ( 312 ), the method ( 300 ) includes determining whether the pressure sensor output is less than or equal to a minimum pressure threshold P MIN  for a predetermined time. That is, the pressure sensor outputs received by controller  160  are compared to a minimum pressure threshold P MIN . The minimum pressure threshold P MIN  corresponds with a liquid level L within sump  138  that provides a degree of safety that dishwasher appliance  100  is not currently flooded or not about to be flooded. In some implementations, in determining whether the pressure sensor output is less than or equal to the minimum pressure threshold P MIN , the pressure sensor output must be consecutively less than or equal to the minimum pressure threshold P MIN  for the predetermined time. In this way, it is less probable or likely that pressure sensor  200  has been inadvertently or nuisance tripped. The predetermined time can be, for example, between about three (3) and five (5) seconds. 
     If at ( 312 ) it is determined that the pressure sensor output is less than or equal to the minimum pressure threshold P MIN  for the predetermined time, then it is determined that there is no longer a flood or threat of a flood within dishwasher  100 , and as will be explained below at ( 314 ), drain pump  168  is deactivated. If, however, at ( 312 ) it is determined that the pressure sensor output is not less than or equal to the minimum pressure threshold P MIN , then a current time T is compared against a predetermined time threshold T 1   MAX  at ( 316 ). 
     At ( 314 ), if the pressure sensor output is less than or equal to the minimum pressure threshold P MIN  for the predetermined time, the method ( 300 ) includes deactivating the drain pump. As noted above, if it is determined at ( 312 ) that the pressure sensor output is less than or equal to the minimum pressure threshold P MIN , then there is no longer a flood event or threat of a flood event. As such, to save energy, drain pump  168  is deactivated. 
     At ( 316 ), if the pressure sensor output is not less than or equal to the minimum pressure threshold P MIN  for the predetermined time, the method ( 300 ) includes determining whether a current time is less than or equal to a predetermined time threshold T 1   MAX . The predetermined time threshold T 1   MAX  can be, for example, twelve (12) hours, twenty-four (24) hours, thirty-six (36) hours, forty-eight hours (48), etc. The predetermined time threshold T 1   MAX  is kept by the timer. 
     If the current time T is less than or equal to the predetermined time threshold T MAX , the controller logic loops back to ( 312 ). In this way, controller  160  can continue to monitor the liquid level L within sump  138 . If the current time T is not less than or equal to predetermined time threshold T 1   MAX , then the controller logic proceeds to ( 318 ). 
     At ( 318 ), if the current time T is not less than or equal to the predetermined time threshold T 1   MAX , the method ( 300 ) includes logging a drain fault. If the current time T is not less than or equal to the predetermined time threshold T 1   MAX , controller  160  recognizes that for one reason or another the wash fluid within sump  138  cannot be removed. For example, in implementations where drain pump  168  is activated and cannot remove the wash fluid from sump  138  within predetermined time threshold T 1   MAX , the system recognizes that there is a malfunction of some component (e.g., water inlet valve  153 ) that is preventing the wash fluid from being drained from sump  138 . The drain fault is logged to assist an operator with taking corrective action. 
     Further, in some implementations at ( 318 ), the method ( 300 ) includes notifying a consumer that there has been a drain failure. In this way, a consumer can take necessary corrective actions to prevent dishwasher  100  from flooding. A consumer may be notified in any of the exemplary ways noted above at ( 310 ). 
     After the logging the drain fault and/or notifying the consumer at ( 318 ), the controller logic proceeds or returns to ( 302 ) to commence the process once again. As noted above, if dishwasher  100  is powered, controller  160  can constantly monitor for flood events. 
     At ( 320 ), if the pressure sensor output is not greater than or equal to either the first pressure threshold or the second pressure threshold as determined at ( 306 ) or ( 308 ), respectively, the method ( 300 ) includes determining whether the tub lip sensor has sensed wash fluid at or proximate the tub lip for a predetermined time. That is, at ( 320 ) it is determined whether the tub lip sensor  202  has sensed wash fluid at or proximate tub lip  170  for a predetermined time. The predetermined time can be, for example, between about three (3) and five (5) seconds. Preferably, in some implementations, in determining whether the tub lip sensor  202  has sensed wash fluid at or proximate tub lip  170  consecutively for the predetermined time. Stated alternatively, tub lip sensor  202  must sense wash fluid at or proximate the tub lip  170  for the predetermined time for the entire predetermined period. In this way, it is less probable or likely that tub lip sensor  202  has been inadvertently or nuisance tripped. 
     As one example, where tub lip sensor  202  is a conductivity sensor as noted above, to sense wash fluid at or proximate tub lip  170 , if the tub lip sensor  202  is closed for a consecutive predetermined time (e.g., wash fluid has breached the leads of the sensor for a consecutive period of time), it may be determined that wash fluid is present at or proximate tub lip  170 , and thus, a flood event has likely occurred or about the occur. If, however, the tub lip sensor  202  remains open or has not closed for a consecutive predetermined time, a determination may be made that wash fluid is not present at or proximate tub lip  170 . Consequently, it may be determined that a flood event has likely not occurred or about to occur. 
     If at ( 320 ) it is determined that tub lip sensor  202  has not sensed wash fluid proximate tub lip  170  for the predetermined time, then it is determined that there is not currently a flood event or about to be a flood event and the controller logic loops back to ( 302 ) and method ( 300 ) begins again as shown in  FIG. 5A . 
     If, however, at ( 320 ) it is determined that tub lip sensor  202  has sensed wash fluid proximate tub lip  170  for the predetermined time, then it is determined that there is presently a flood event or about to be a flood event in dishwasher  100 . As such, the controller logic proceeds to ( 322 ). In such an event, it is possible that the pressure sensor  200  gave a false positive at ( 306 ) or ( 308 ) or has malfunctioned. Thus, in accordance with exemplary aspects of the present disclosure, corrective action may be taken. 
     At ( 322 ), the method ( 300 ) includes activating the drain pump if the tub lip sensor has sensed wash fluid at or proximate the tub lip for the predetermined time. Thus, corrective action in response to the detected flood event can be taken. Preferably, drain pump  168  removes wash fluid from dishwasher  100  at a faster rate than water and/or wash fluid flows into sump  138 . In this manner, drain pump  168  can overcome the flow rate of water inlet valve  153 , particularly if water inlet valve  153  has failed. 
     In some implementations, at ( 322 ) the method ( 300 ) includes starting a timer. In such implementations, as will be explained further below, the timer is started so that if the liquid level L within sump  138  is not below a certain threshold within a predetermined time, the consumer is notified so that corrective action may be taken. Moreover, preferably, the starting of the timer is coordinated with the activation of drain pump  168 . That is, the timer is started upon activation of drain pump  168 . In this way, the activated drain pump  168  does not run indefinitely without the consumer being notified in the event the drain pump  168  simply cannot remove the wash fluid from dishwasher  100 , e.g., due to a water inlet valve failure. This may also, for example, improve the service life of drain pump  168 . 
     In implementations where dishwasher  100  is operating a cycle, the method ( 300 ) includes canceling a current cycle of the dishwasher appliance if the tub lip sensor has sensed wash fluid at or proximate the tub lip for the predetermined time. When wash fluid is sensed or detected at or proximate tub lip  170  or at a given distance from tub lip  170 , controller  160  determines that a flood event has occurred or that a flood event is imminent. Thus, in response, dishwasher  100  can take corrective action to prevent or mitigate the effects of the flood event, as noted above. 
     By way of example, if dishwasher  100  is performing a wash or rinse cycle, canceling the current cycle includes deactivating the inlet water valve and/or deactivating the circulation pump. Deactivating water inlet valve  153  (e.g., closing the valve to a closed position) prevents further water from entering dishwasher  100 . Deactivating circulation pump  152  ceases the circulation of wash fluid through or about dishwasher  100 . In this way, energy can be conserved and will allow the wash fluid to flow back to sump  138  such that it can be removed from dishwasher  100 . 
     In some further implementations, at ( 322 ), the method ( 300 ) includes logging a flood fault. In this way, if dishwasher  100  is serviced, an operator can quickly ascertain why dishwasher  100  was cancelled mid-cycle. Moreover, in some implementations, as shown at ( 322 ), the method ( 300 ) includes notifying a consumer that the cycle has been cancelled and that a flood event or possible flood event has occurred. For instance, as noted previously, dishwasher  100  may include a speaker that audibly communicates the notification to a consumer. As another example, dishwasher  100  may include a communication interface that is communicatively coupled with controller  160 . The communication interface may include a network interface that provides for communication over a network, such as e.g., a wireless network. In such implementations, dishwasher  100  may send notifications to a consumer&#39;s user device, such as e.g., a watch. 
     At ( 324 ), after canceling and/or activating the drain pump at ( 322 ), the method ( 300 ) includes determining whether the tub lip sensor has sensed wash fluid at or proximate the tub lip for a predetermined time. Stated alternatively, after one or more corrective actions are taken, e.g., canceling the current cycle and/or activating the drum pump, controller  160  monitors whether the wash fluid within sump  138  and tub  104  has receded for a predetermined time, such as e.g., about three (3) to five (5) seconds. As one example, the controller  160  can determine whether the tub lip sensor  202  has been electrically opened consecutively for a predetermined time (e.g., two (2) seconds). Stated differently, the controller  160  can determine whether wash fluid has bridged the electrical leads of the conductivity tub lip sensor  202  for a predetermined time. 
     If at ( 324 ) it is determined that the tub lip sensor has not sensed wash fluid at or proximate the tub lip for the predetermined time, then it is determined that there is no longer a flood event or threat of a flood event within dishwasher  100 , and as will be explained below at ( 326 ), drain pump  168  is deactivated. If, however, at ( 324 ) it is determined that the tub lip sensor has sensed wash fluid at or proximate the tub lip for the predetermined time, then the current time T is compared against a predetermined time threshold T 2   MAX  at ( 328 ). 
     At ( 326 ), the method ( 300 ) includes if the tub lip sensor has not sensed wash fluid at or proximate the tub lip for a predetermined time as determined at ( 324 ), the method ( 300 ) includes deactivating the drain pump. As noted above, if it is determined at ( 324 ) that the tub lip sensor has not sensed wash fluid at or proximate the tub lip for the predetermined time, then there is no longer a flood event or threat of a flood event. As such, to save energy, drain pump  168  is deactivated. 
     At ( 328 ), if the tub lip sensor has sensed wash fluid proximate the tub lip for the predetermined time at ( 324 ), the method ( 300 ) includes determining whether current time T is less than or equal to a predetermined time threshold T 2   MAX . The predetermined time threshold T 2   MAX  can be, for example, twelve (12) hours, twenty-four (24) hours, thirty-six (36) hours, forty-eight hours (48), etc. The predetermined time threshold T 2   MAX  is kept by the timer. 
     If the current time T is less than or equal to the predetermined time threshold T 2   MAX , the controller logic loops back to ( 324 ). In this way, controller  160  can continue to monitor whether wash fluid is at or proximate tub lip  170 . If the current time T is not less than or equal to predetermined time threshold T 2   MAX , then the controller logic proceeds to ( 330 ). 
     At ( 330 ), if the current time T is not less than or equal to the predetermined time threshold T 2   MAX , the method ( 300 ) includes logging a drain fault. If the current time T is not less than or equal to the predetermined time threshold T 2   MAX , controller  160  recognizes that the wash fluid proximate or at tub lip  170  has not receded. For example, in implementations where drain pump  168  is activated and cannot remove the wash fluid from sump  138  and tub  104  within predetermined time threshold T 2   MAX , the system recognizes that there is a malfunction of some component (e.g., water inlet valve  153 ) that is preventing the wash fluid from being drained from dishwasher  100 . The drain fault is logged to assist an operator with taking corrective action. 
     Further, in some implementations at ( 330 ), the method ( 300 ) includes notifying a consumer that there has been a drain failure. In this way, a consumer can take necessary corrective actions to prevent dishwasher  100  from flooding. A consumer may be notified in any of the exemplary ways noted above at ( 310 ) and ( 322 ). 
     After the logging the drain fault and/or notifying the consumer at ( 330 ), the controller logic proceeds or returns to ( 302 ) to commence the process once again. As noted above, if dishwasher  100  is powered, controller  160  can constantly monitor for flood events. 
     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.