Patent Publication Number: US-11035071-B2

Title: Method for drain standpipe height detection

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to methods for detecting drain standpipe height in washing machine appliances. 
     BACKGROUND OF THE INVENTION 
     Washing machine appliances include a pump that drains wash fluid from within a tub. The pump flows the wash fluid to a drain standpipe that is a component of a building housing the washing machine appliance. A height of the drain standpipe varies between buildings. The height of the drain standpipe is normally about three feet (3′). However, in certain buildings, the height of the drain standpipe can be eight feet (8′) or more. 
     High drain standpipes pose challenges. For example, washing machine appliances are frequently programmed to run the drain pump for a predetermined period of time that is selected to fully drain the tub under normal conditions. However, in buildings with high drain standpipes, the drain pump can require more time to fully drain the tub. If the drain pump does not have sufficient time or capacity to fully drain the tub, then wash water can remain with a sump of the tub. Such wash water can negatively affect rotation of a basket within the tub and/or generate an undesirable soap sud condition within the tub. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention. 
     In a first example embodiment, a method for detecting drain standpipe height in a washing machine appliance includes activating a drain pump such that the drain pump flows wash fluid from a tub to a drain standpipe, receiving a signal from a pressure sensor associated with the tub while the drain pump flows the wash fluid from the tub to the drain standpipe, determining a height of the drain standpipe based on the signal from the pressure sensor, and adjusting operation of the washing machine appliance in response to the determined height of the drain standpipe. 
     In a second example embodiment, a washing machine appliance includes a tub and a basket within the tub. A motor is coupled to the basket. The motor is operable to rotate the basket within the tub. A drain pump is operable to flow wash fluid from the tub. A pressure sensor is in fluid communication with the tub. A signal from the pressure sensor is variable as a function of wash fluid height within the tub. A controller is in operative communication with the motor, the drain pump and the pressure sensor. The controller is configured to activate the drain pump such that the drain pump flows the wash fluid from the tub to a drain standpipe, receive the signal from the pressure sensor while the drain pump flows the wash fluid from the tub to the drain standpipe, determine a height of the drain standpipe based on the signal from the pressure sensor, and adjust operation of the washing machine appliance in response to the determined height of the drain standpipe. 
     In a third example embodiment, a method for detecting drain standpipe height in a washing machine appliance includes activating a drain pump such that the drain pump flows wash fluid from a tub to a drain standpipe, measuring one or both of a current through the drain pump and a power consumption of the drain pump while the drain pump flows the wash fluid from the tub to the drain standpipe, determining a height of the drain standpipe based on the measured one or both of the current through the drain pump and the power consumption of the drain pump, and adjusting operation of the washing machine appliance in response to the determined height of the drain standpipe. 
     In a fourth example embodiment, a washing machine appliance includes a tub and a basket within the tub. A motor is coupled to the basket. The motor is operable to rotate the basket within the tub. A drain pump is operable to flow wash fluid from the tub. A controller is in operative communication with the motor and the drain pump. The controller is configured to activate the drain pump such that the drain pump flows the wash fluid from the tub to a drain standpipe, measure one or both of a current through the drain pump and a power consumption of the drain pump while the drain pump flows the wash fluid from the tub to the drain standpipe, determine a height of the drain standpipe based on the measured one or both of the current through the drain pump and the power consumption of the drain pump, and adjust operation of the washing machine appliance in response to the determined height of the drain standpipe. 
     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  is a perspective view of a washing machine appliance according an example embodiment of the present subject matter. 
         FIG. 2  is a section view of the example washing machine appliance of  FIG. 1 . 
         FIG. 3  is a schematic view of certain components of the example washing machine appliance of  FIG. 1 . 
         FIG. 4  is a plot of a pressure signal versus time during a drain standpipe height detection method according to an example embodiment of the present subject matter. 
         FIG. 5  is a plot of a current versus time during a drain standpipe height detection method according to an example embodiment of the present subject matter. 
     
    
    
     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 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. 
       FIG. 1  provides a perspective view partially broken away of a washing machine appliance  50  according to an exemplary embodiment of the present subject matter. As may be seen in  FIG. 1 , washing machine appliance  50  defines a vertical direction V, a lateral direction L and a transverse direction T. The vertical direction V, lateral direction L and transverse direction T are mutually perpendicular and form an orthogonal direction system. 
     Washing machine appliance  50  includes a cabinet or apron  52  and a top panel or cover  54 . A backsplash  56  extends from cover  54 , and a control panel  58  including a plurality of input selectors  60  is coupled to backsplash  56 . Control panel  58  and input selectors  60  collectively form a user interface input for operator selection of machine cycles and features, and in one embodiment a display  61  indicates selected features, a countdown timer, and other items of interest to machine users. A lid  62  is mounted to cover  54  and is rotatable about a hinge (not shown) between an open position (not shown) facilitating access to a wash tub  64  located within apron  52 , and a closed position (shown in  FIG. 1 ) forming a sealed enclosure over wash tub  64 . 
     As illustrated in  FIG. 1 , washing machine appliance  50  is a vertical axis washing machine appliance. While the present disclosure is discussed with reference to a vertical axis washing machine appliance, those of ordinary skill in the art, using the disclosures provided herein, should understand that the subject matter of the present disclosure is equally applicable to other washing machine appliances, such as horizontal axis washing machine appliances. 
     A sub-washer unit  65  ( FIG. 2 ) is mounted within apron  52 . Sub-washer unit  65  includes tub  64  and a basket  70 . Tub  64  includes a bottom wall  66  and a cylindrical side wall  68 , and basket  70  is rotatably mounted within wash tub  64 . Bottom wall  66  of tub  64  is spaced, e.g., vertically, from an open top end of cylindrical side wall  68 . A pump assembly  72  is located beneath tub  64  and basket  70  for gravity assisted flow when draining tub  64 . Pump assembly  72  includes a pump  74  and a motor  76 . A pump inlet hose  80  extends from a wash tub outlet  82  in tub bottom wall  66  to a pump inlet  84 , and a pump outlet hose  86  extends from a pump outlet  88  to an appliance washing machine water outlet  90  and ultimately to a building plumbing system discharge line (not shown) in flow communication with outlet  90 . 
     As shown in  FIG. 3 , pump assembly  72  may be mounted to tub  64  in alternative example embodiments. In particular, pump assembly  72  may be mounted directly to the bottom side of subwasher unit  65 . Wash fluid may drain under gravity from tub  64  is pumped out of appliance  50  via pump assembly  72 . The displaced wash fluid passes through a flexible bellows type hose  48 , which has a discharge end attached to a rear panel mounted bracket  49 , during operation of pump assembly  72 . 
       FIG. 2  provides a front elevation schematic view of certain components washing machine appliance  50  including wash basket  70  movably disposed and rotatably mounted in wash tub  64  in a spaced apart relationship from tub side wall  68  and tub bottom  66 . Basket  70  includes a plurality of perforations therein to facilitate fluid communication between an interior of basket  70  and wash tub  64 . 
     A hot liquid valve  102  and a cold liquid valve  104  deliver fluid, such as water, to basket  70  and wash tub  64  through a respective hot liquid hose  106  and a cold liquid hose  108 . Liquid valves  102 ,  104  and liquid hoses  106 ,  108  together form a liquid supply connection for washing machine appliance  50  and, when connected to a building plumbing system (not shown), provide a fresh water supply for use in washing machine appliance  50 . Liquid valves  102 ,  104  and liquid hoses  106 ,  108  are connected to a basket inlet tube  110 , and fluid is dispersed from inlet tube  110  through a nozzle assembly  112  having a number of openings therein to direct washing liquid into basket  70  at a given trajectory and velocity. A dispenser (not shown in  FIG. 2 ), may also be provided to produce a wash solution by mixing fresh water with a known detergent or other composition for cleansing of articles in basket  70 . 
     An agitation element  116 , such as a vane agitator, impeller, auger, or oscillatory basket mechanism, or some combination thereof is disposed in basket  70  to impart an oscillatory motion to articles and liquid in basket  70 . In various exemplary embodiments, agitation element  116  may be a single action element (oscillatory only), double action (oscillatory movement at one end, single direction rotation at the other end) or triple action (oscillatory movement plus single direction rotation at one end, single direction rotation at the other end). As illustrated in  FIG. 2 , agitation element  116  is oriented to rotate about a vertical axis  118 . 
     Basket  70  and agitator  116  are driven by a motor  120  through a transmission and clutch system  122 . The motor  120  drives shaft  126  to rotate basket  70  within wash tub  64 . Clutch system  122  facilitates driving engagement of basket  70  and agitation element  116  for rotatable movement within wash tub  64 , and clutch system  122  facilitates relative rotation of basket  70  and agitation element  116  for selected portions of wash cycles. Motor  120  and transmission and clutch system  122  collectively are referred herein as a motor assembly  148  and may be a component of sub-washer unit  65 . 
     Sub-washer unit  65  further includes a vibration damping suspension system or mount  92  for supporting sub-washer unit  65  within apron  52 . One end of mount  92  may be connected to sub-washer unit  65  while an opposite end of mount  92  is receivable within and/or coupled to at least one bracket  98 . Thus, mount  92  may extend between sub-washer unit  65  and bracket  98  in order to suspend sub-washer unit  65  within apron  52 . 
     Mount  92  can include a plurality of damping elements, such as piston-cylinder damping elements, coupled to the wash tub  64 . The damping suspension system  92  can include other elements, such as a balance ring  94  disposed around the upper circumferential surface of the wash basket  70 . The balance ring  94  can be used to counterbalance an out of balance condition for the wash machine as the basket  70  rotates within the wash tub  64 . 
     Operation of washing machine appliance  50  is controlled by a controller (not shown) which is operatively coupled to the user interface input located on washing machine backsplash  56  (shown in  FIG. 1 ) for user manipulation to select washing machine cycles and features. In response to user manipulation of the user interface input, the controller operates the various components of washing machine appliance  50  to execute selected machine cycles and features. 
     In an illustrative embodiment, laundry items are loaded into basket  70 , and washing operation is initiated through operator manipulation of control input selectors  60  (shown in  FIG. 1 ). Tub  64  is filled with water and mixed with detergent to form a wash fluid, and basket  70  is agitated with agitation element  116  for cleansing of laundry items in basket  70 . That is, agitation element is moved back and forth in an oscillatory back and forth motion. In the illustrated embodiment, agitation element  116  is rotated clockwise a specified amount about the vertical axis of the machine, and then rotated counterclockwise by a specified amount. The clockwise and counterclockwise reciprocating motion is sometimes referred to as a stroke, and the agitation phase of the wash cycle constitutes a number of strokes in sequence. Acceleration and deceleration of agitation element  116  during the strokes imparts mechanical energy to articles in basket  70  for cleansing action. The strokes may be obtained in different embodiments with a reversing motor, a reversible clutch, or other known reciprocating mechanism. After the agitation phase of the wash cycle is completed, tub  64  is drained with pump assembly  72 . Laundry items are then rinsed and portions of the cycle may be repeated, including the agitation phase, depending on the particulars of the wash cycle selected by a user. 
       FIG. 3  is schematic view of certain components of washing machine appliance  50 . As may be seen in  FIG. 3 , washing machine appliance  50  includes a wash fluid height sensor  124 , a controller or control board  200  and a wiring harness  220 . Control board  200  is positioned within apron  52 , e.g., within backsplash  56 . Wiring harness  220  electrically connects control board  200  with one or more electrical components, such as motor  76 , motor  120  and wash fluid height sensor  124 . Thus, e.g., wiring harness  220  may extend between control board  200  and the one or more electrical components. 
     Control board  200  may include one or more processors and a memory. The processor(s) of control board  200  can be any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, or other suitable processing device. The memory of control board  200  can include any suitable computing system or media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, or other memory devices. The memory of control board  200  can store information accessible by the processor(s) of control board  200 , including instructions that can be executed by the processor(s) to control various components of washing machine appliance  50  to provide appliance functionality and data. Thus, the combination of one or more processors and memory may correspond to a controller configured to implement various programs or methods to operate washing machine appliance  50 . Input/output (“I/O”) signals may be routed between control board  200  and various operational components of washing machine appliance  50 , including the one or more electrical components, along wiring harness  220  within washing machine appliance  50 . Wiring harnesses  220  may include a plurality of conductive wires. 
     Control board  200  may be configured for measuring one or both of a current through pump assembly  72  and a power consumption of pump assembly  72 . For example, control board  200  may include a sensor  127 , such as an ammeter, for measuring one or both of the current through pump assembly  72  and the power consumption of pump assembly  72 . Thus, control board  200  may receive a signal from sensor  127  that corresponds to the one or both of the current through pump assembly  72  and the power consumption of pump assembly  72 . 
     Wash fluid height sensor  124  is operable to measure the height of wash fluid within tub  68 . For example, wash fluid height sensor  124  may be in fluid communication with tub  68  via a hose  125  that extends between tub  68  and wash fluid height sensor  124 . A pressure of air within hose  125  may vary as a function of the height of wash fluid within tub  68 , and wash fluid height sensor  124  may be configured for measuring the pressure of air within hose  125 . Thus, wash fluid height sensor  124  may be a pressure sensor, and a signal from wash fluid height sensor  124  may vary as a function of the height of wash fluid within tub  68 . Control board  200  may receive the signal from wash fluid height sensor  124  to establish the height of wash fluid within tub  68 . 
     Washing machine appliance  50  may include a drain hose  47  that extends from rear panel mounted bracket  49 . An end of drain hose  47  may be received within a drain standpipe  51 . Thus, wash fluid from pump assembly  72  may flow through drain hose  47  into drain standpipe  51 . Drain standpipe  51  is a component of a building housing washing machine appliance  50 . Thus, a height HS of drain standpipe  51  may vary between buildings. The height HS of drain standpipe  51  may correspond to a vertical distance between a bottom of washing machine appliance  50  (e.g., or rear panel mounted bracket  49 ) and a top of drain standpipe  51  (e.g., at which drain hose  47  is inserted into drain standpipe  51 ). 
     Due to variations of the height HS of drain standpipe  51  between buildings, pump assembly  72  may have a different drain rate between buildings. For example, when washing machine appliance  50  is installed within a building in which the height HS of drain standpipe  51  is eight feet (8′), the drain rate of pump assembly  72  may be relatively low compared to when washing machine appliance  50  is installed within a building in which the height HS of drain standpipe  51  is three feet (3′). As discussed in greater detail below, washing machine appliance  50  includes features for determining the height HS of drain standpipe  51 , e.g., and adjusting operation of washing machine appliance  50  to account for the determined height HS. 
     An example method for detecting drain standpipe heights in washing machine appliances will now be described. The control board  200  of washing machine appliance  50  may run the drain standpipe height detection method in order to ensure proper operation of washing machine appliance  50 . The drain standpipe height detection method may advantageously allow operation of washing machine appliance  50  to account for various heights HS of drain standpipes  51  between buildings and allow suitable draining of tub  68  by pump assembly  72  despite the various heights HS of drain standpipes  51 . It will be understood that while discussed below in a certain sequence, the drain standpipe height detection method may be performed in other suitable sequences in alternative example embodiments. Thus, the drain standpipe height detection method is not limited to the particular sequence described below. 
     Initially, pump assembly  72  may be activated such that pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . In particular, control board  200  may power motor  76  to drive pump  74  within pump assembly  72 . Pump  74  may urge wash fluid from tub  68  out of washing machine appliance  50  to drain standpipe  51 . In particular, pump  74  may flow the wash fluid from tub  68  up the height HS of drain standpipe  51  during operation of pump assembly  72 . While pump assembly  72  is activated and flowing wash fluid from tub  68  to drain standpipe  51 , the drain standpipe height detection method may detect the height HS of drain standpipe  51  using various mechanisms. 
     As a first example, with reference to  FIG. 4 , wash fluid height sensor  124  tracks the height of wash fluid within tub  68  while pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . As noted above, wash fluid height sensor  124  may be a pressure sensor such that the signal from wash fluid height sensor  124  to control board  200  varies as a function of the height of wash fluid within tub  68 . Thus, control board  200  may track the height of wash fluid within tub  68  with the signal from wash fluid height sensor  124 . The height HS of drain standpipe  51  may be determined based on the signal from wash fluid height sensor  124 . As an example, the height HS of drain standpipe  51  may be determined by calculating a rate of change in the signal from wash fluid height sensor  124  over time while pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . The height HS of drain standpipe  51  may be proportional to the rate of change in the signal from wash fluid height sensor  124  while pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . 
     As shown in  FIG. 4 , a magnitude of the rate of change in the signal from wash fluid height sensor  124  when the height HS of drain standpipe  51  is three feet (3′) may be greater than the magnitude of the rate of change in the signal from wash fluid height sensor  124  when the height HS of drain standpipe  51  is eight feet (8′). A drain standpipe height of three feet (3′) may correspond to a normal drain standpipe height, and drain standpipe heights significantly greater than three feet (3′), e.g., two more feet greater, may correspond to high drain standpipe heights. Thus, the magnitude of the rate of change in the signal from wash fluid height sensor  124  may be relatively high when the height HS of drain standpipe  51  is normal, and the magnitude of the rate of change in the signal from wash fluid height sensor  124  may be relatively low when the height HS of drain standpipe  51  is greater than normal. As may be seen from the above, e.g., pump assembly  72  may have a normal drain rate when the height HS of drain standpipe  51  is normal (e.g., when the magnitude of the rate of change in the signal from wash fluid height sensor  124  over time is greater than a threshold value). Conversely, pump assembly  72  may have a low drain rate when the height HS of drain standpipe  51  is greater than normal (e.g., when the magnitude of the rate of change in the signal from wash fluid height sensor  124  over time is less than the threshold value). 
     The rate of change may be determined during a time interval T 1  after activating pump assembly  72  to flow wash fluid from tub  68  to drain standpipe  51 . The time interval T 1  may be any suitable duration, e.g., three seconds (3 s), five seconds (5 s), ten seconds (10 s), etc. Such durations may provide suitable data from wash fluid height sensor  124  to account for noise in the signal from wash fluid height sensor  124 . The time interval T 1  may also begin at any suitable time after activating pump assembly  72 , e.g., ten seconds (10 s), twenty seconds (20 s), thirty seconds (30 s), etc. after activating pump assembly  72 . Such delay may provide sufficient time for pump assembly  72  to begin steadily pumping wash fluid from tub  68  to drain standpipe  51 . 
     As a second example, with reference to  FIG. 5 , control board  200  may measure one or both of the current through pump assembly  72  and the power consumption of pump assembly  72 , e.g., with sensor  127 , while pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . The height HS of drain standpipe  51  may be determined based on one or both of the current through pump assembly  72  and the power consumption of pump assembly  72 . As an example, the height HS of drain standpipe  51  may be proportional to one or both of the current through pump assembly  72  and the power consumption of pump assembly  72  while pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . Thus, control board  200  may track one or both of the current through pump assembly  72  and the power consumption of pump assembly  72  while pump assembly  72  flows wash fluid from tub  68  to drain standpipe  51 . 
     As shown in  FIG. 5 , a magnitude of the current through pump assembly  72  when the height HS of drain standpipe  51  is three feet (3′) may be greater than the magnitude of the current through pump assembly  72  when the height HS of drain standpipe  51  is eight feet (8′). As noted above, a drain standpipe height of three feet (3′) may correspond to a normal drain standpipe height, and drain standpipe heights significantly greater than three feet (3′), e.g., two more feet greater, may correspond to high drain standpipe heights. Thus, the magnitude of the current through pump assembly  72  may be relatively high when the height HS of drain standpipe  51  is normal, and the magnitude of the current through pump assembly  72  may be relatively low when the height HS of drain standpipe  51  is greater than normal. As may be seen from the above, e.g., pump assembly  72  may have a normal drain rate when the height HS of drain standpipe  51  is normal (e.g., when the magnitude of the current through pump assembly  72  is greater than a threshold value). Conversely, pump assembly  72  may have a low drain rate when the height HS of drain standpipe  51  is greater than normal (e.g., when the magnitude of the current through pump assembly  72  is less than the threshold value). While only the current through pump assembly  72  is shown in  FIG. 5 , it will be understood that the power consumption of pump assembly  72  may behave in the same manner as that described above for the current through pump assembly  72 . 
     The average magnitude of the current through pump assembly  72  (and/or the power consumption of pump assembly  72 ) may be determined during the time interval T 1  after activating pump assembly  72  to flow wash fluid from tub  68  to drain standpipe  51 , e.g., in the manner described above in the context of  FIG. 4 . As shown in  FIG. 5 , the current through pump assembly  72  may also significantly decrease after the time interval T 1 , e.g., when pump assembly  72  fully drains tub  68  and draws air. As shown in  FIG. 5 , the current through pump assembly  72  may significantly decrease at a time T 2  after activating pump assembly  72  to flow wash fluid from tub  68  to drain standpipe  51  when the height HS of drain standpipe  51  is three feet (3′). Conversely, the current through pump assembly  72  may significantly decrease at a time T 3  after activating pump assembly  72  to flow wash fluid from tub  68  to drain standpipe  51  when the height HS of drain standpipe  51  is eight feet (8′). The time T 3  is later than the time T 2  when tub  68  holds the same volume of wash fluid due to the increased height HS of drain standpipe  51 . 
     After determining the height HS of drain standpipe  51 , operation of washing machine appliance  50  is adjusted in response to the determined height HS of drain standpipe  51 . As an example, control board  200  may be configured to adjust operation of washing machine appliance  50  by one or more of modifying a drain profile of pump assembly  72 , modifying a spin profile of basket  70  during a spin cycle, and modifying a rinse profile during a rinse cycle when the height HS of drain standpipe  51  is the low drain rate. In particular, control board  200  may be configured to extending the spin cycle, decreasing a rotational speed and/or acceleration of basket  70  during the spin cycle, and/or conducting an additional rinse cycle or a different rinse cycle, such as a warm rinse or a deep rinse, in response to the determined height HS of drain standpipe  51 . In particular, when the height HS of drain standpipe  51  is greater than a normal drain standpipe height (e.g., and pump assembly  72  takes longer to drain tub  68 ), control board  200  may adjust operation of washing machine appliance  50  by one or more of modifying the drain profile of pump assembly  72 , modifying the spin profile of basket  70  during the spin cycle, and modifying the rinse profile during the rinse cycle to allow additional draining of tub  68  and/or prevent excessive soap sud formation within tub  68 . 
     The drain standpipe height detection method described above may assist with sensing the height HS of drain standpipe  51 . The sensed height HS of drain standpipe  51  may advantageously allow customization of cycle parameters based on installation specifics of washing machine appliance  50 . 
     In certain example embodiments, the height HS of drain standpipe  51  may be saved within the memory of control board  200 . When the height HS of drain standpipe  51  is saved within the memory of control board  200 , a wash cycle may be modified for subsequent wash cycles in the following manner, e.g., to minimize soap sud formation within tub  68 . As an example, detergent dosing may be modified when washing machine appliance  50  is equipped with a bulk dispense system. To compensate for the reduced detergent dose, washing machine appliance  50  may modify the wash cycle by extending agitation/tumbling duration, and/or by increasing wash fluid temperature. As another example, washing machine appliance  50  may add additional water into tub  68  during the wash agitation/tumbling phase to dilute the wash fluid prior to the drain cycle. 
     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.