Patent Publication Number: US-9422659-B2

Title: Washing machine appliance and a method of operating the same

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to washing machine appliances and methods for operating washing machine appliances. 
     BACKGROUND OF THE INVENTION 
     Washing machine appliances can use a variety of fluid additives (in addition to water) to assist with washing and rinsing a load of articles. For example, detergents and/or stain removers may be added during wash and prewash cycles of washing machine appliances. As another example, fabric softeners may be added during rinse cycles of washing machine appliances. 
     Fluid additives are preferably introduced at an appropriate time during the operation of washing machine appliance and in a proper volume. By way of example, adding laundry detergent and fabric softener simultaneously to liquid water used for a laundry load can negatively affect operation of the washing machine appliance because the two fluid additives can negate each other. Adding insufficient volumes of either the detergent or the fabric softener to the laundry load can also negatively affect washing machine appliance operations by diminishing efficacy of a cleaning operation. Similarly, adding excessive volumes of either the detergent or the fabric softener can also negatively affect washing machine appliance operations by diminishing efficacy of a cleaning operation. 
     For instance, when too much detergent is added during a wash cycle, detergent can remain in articles after a rinse cycle because the rinse cycle may not be able to remove all of the detergent from the articles. Unremoved detergent can cause graying within such articles as the detergent builds up over time, can contribute to a roughness feeling of such articles, and can trigger skin allergies. The unremoved detergent can also negatively affect the efficacy of fabric softener during the rinse cycle. Further, unremoved detergent can also cause excess suds that can damage the washing machine and/or decrease a spin speed of the washing machine appliance&#39;s drum thereby causing articles therein to retain excessive liquids. 
     As a convenience to the consumer, certain washing machine appliances include systems for automatically dispensing detergent and/or fabric softener. Such systems can store one or more fluid additives in bulk and dispense such fluid additives during operation of the washing machine appliances. However, accurately dispensing a particular volume of fluid additive with such systems can be difficult. For example, hoses or other conduits are typically used to direct fluid additive from a tank to the washing machine appliance&#39;s tub. Air within such hoses can negatively affect measurements of fluid additive dispensed by such systems. 
     Accordingly, a washing machine appliance with features for accurately dispensing a volume of fluid additive would be useful. In particular, a washing machine appliance with features for accurately dispensing a volume of fluid additive despite the presence of air within a dispensing system of the washing machine appliance would be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present subject matter provides a washing machine appliance and a method for operating a washing machine appliance. The method includes monitoring a flow rate of fluid additive with a flow meter and measuring a volume of fluid additive dispensed after the flow rate of fluid additive substantially decreases. The method can assist with accurately and/or precisely dispensing fluid additive during operating of the washing machine appliance. Additional 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 exemplary embodiment, a washing machine appliance is provided. The washing machine appliance includes a Venturi pump. An inlet conduit is configured for directing a flow of liquid water to the Venturi pump. A valve is configured for regulating the flow of liquid water in the inlet conduit. An outlet conduit is configured for directing a flow of wash fluid out of the Venturi pump. The washing machine appliance also includes an additive dispensing system. The additive dispensing system includes a tank that defines a volume. The volume of the tank configured for receipt of a fluid additive. An additive conduit extends between the tank and the Venturi pump. A flow meter is configured for measuring a flow of fluid additive through the additive conduit. A controller is in communication with the valve and the flow meter. The controller is configured for actuating the valve to an open configuration in order to initiate the flow of liquid water to the Venturi pump through the inlet conduit, monitoring a flow rate of fluid flowing through the additive conduit to the Venturi pump with the flow meter after the step of actuating, measuring a volume of fluid additive dispensed at the Venturi pump after the flow rate of fluid flowing through the additive conduit to the Venturi pump decreases by at least a predetermined amount during the step of monitoring, and operating the valve to a closed configuration in order to hinder the flow of liquid water to the Venturi pump through the inlet conduit after a predetermined volume of fluid additive has been dispensed at the Venturi pump. 
     In a second exemplary embodiment, a method for operating a washing machine appliance is provided. The method includes actuating a valve of the washing machine appliance to an open configuration in order to initiate a flow of liquid through a Venturi pump of the washing machine appliance. The Venturi pump draws fluid additive from a tank of the washing machine appliance into the flow of liquid through the Venturi pump after the step of actuating. The method also includes monitoring a flow rate of fluid additive from the tank to the Venturi pump with a flow meter of the washing machine appliance after the step of actuating, measuring a volume of fluid additive dispensed at the Venturi pump after the flow rate of fluid flowing from the tank to the Venturi pump substantially decreases during the step of monitoring, and operating the valve to a closed configuration in order to hinder the flow of liquid to the Venturi pump after a predetermined volume of fluid additive has been dispensed at the Venturi pump. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures. 
         FIG. 1  provides a front, perspective view of a washing machine appliance according to an exemplary embodiment of the present subject matter. 
         FIGS. 2, 3, 4 and 5  provide schematic views of certain components of the exemplary washing machine appliance of  FIG. 1  with a fluid additive dispensing system of the exemplary washing machine appliance shown in various operation states. 
         FIG. 6  provides exemplary plots of a volume of fluid additive within a tank of a fluid additive dispensing system and a flow rate of fluid through an additive conduit of the fluid additive dispensing system versus time. 
     
    
    
     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 front, perspective view of a washing machine appliance  100  according to an exemplary embodiment of the present subject matter. A drum  120  of washing machine appliance  100  is configured for rotating on a substantially horizontal axis. Thus, washing machine appliance  100  is generally referred to as a horizontal axis washing machine appliance. Using the teachings disclosed herein, it will be understood that washing machine appliance  100  is provided by way of example only. Other washing machine appliances having different configurations, different appearances, and/or different features may also be utilized with the present subject matter as well. For example, the present subject matter may be used with vertical axis washing machine appliances. 
     Washing machine appliance  100  has a cabinet  102  with a drum  120  rotatably mounted therein. A motor (not shown) is in mechanical communication with drum  120  in order to selectively rotate drum  120  (e.g., during an agitation or a rinse cycle of washing machine appliance  100 ). Drum  120  defines a wash chamber  122  that is configured for receipt of articles for washing. Ribs  126  extend from drum  120  into wash chamber  122 . Ribs  126  assist agitation of articles disposed within wash chamber  122  during operation of washing machine appliance  100 . For example, ribs  126  may lift articles disposed in drum  120  during rotation of drum  120 . Drum  120  also defines a plurality of holes  124 . Holes  124  are configured to permit a flow of wash fluid between an interior of drum  120  and an exterior of drum  120 . 
     Cabinet  102  of washing machine appliance  100  has a front panel  104 . A detergent drawer  106  is slidably mounted within front panel  104 . Detergent drawer  106  receives detergent and directs said detergent to wash chamber  122  during operation of appliance  100 . As discussed in greater detail below, washing machine appliance  100  also includes features for bulk dispensing of detergent and/or other fluid additives. Thus, a user need not utilize detergent drawer  106  during each operation of washing machine appliance  100 . 
     Front panel  104  defines an opening  105  that permits user access to wash chamber  122  of drum  120 . A door  130  is mounted to front panel  104  with a hinge  140 . Door  130  provides selective access to wash chamber  122 . A user may selectively adjust door  130  between a closed positioned (not shown) and an open position (shown in  FIG. 1 ) in which the user may access wash chamber  122  of drum  120 . A user may adjust door  130  between the open and closed configurations by rotating door  130  about hinge  140 . For example, to open door  130  from closed configuration, the user may pull on a handle  150  in order to rotate door  130  open. 
     Front panel  104  also includes a control panel  110  with a plurality of input selectors  112 . Control panel  110  and input selectors  112  collectively form a user interface input for operator selection of machine cycles and features. A display  114  of control panel  110  indicates selected features, a countdown timer, and/or other items of interest to appliance users. 
       FIGS. 2, 3, 4 and 5  provide schematic views of certain components of washing machine appliance  100  with a fluid additive dispensing system  180  of washing machine appliance  100  shown in various operation states. As may be seen in  FIGS. 2-5 , washing machine appliance  100  includes a Venturi pump  170 , an inlet conduit  172 , an outlet conduit  174 , and a nozzle  176 . Inlet conduit  172  extends between a water supply  190  and Venturi pump  170 . In particular, inlet conduit  172  extends between an entrance  192  and an exit  194 . Entrance  192  of inlet conduit  172  is positioned at water supply  190  is configured for receipt of liquid water from water supply  190 . Conversely, exit  194  of inlet conduit  172  is positioned at or mounted to Venturi pump  170  and is configured for directing liquid water from water supply  190  into Venturi pump  170 . Inlet conduit  172  can include any suitable mechanism for containing and directing a flow of liquid water therethrough. For example, inlet conduit  172  may include piping, hoses, tubing, combinations thereof, etc. 
     Water supply  190  can be any suitable source of liquid water. For example, water supply  190  may be a municipal water supply or a well. As will be understood by those skilled in the art and as used herein, the term “water” includes purified water and solutions or mixtures containing water and, e.g., elements (such as calcium, chlorine, and fluorine), salts, bacteria, nitrates, organics, and other chemical compounds or substances. 
     As discussed in greater detail below, when liquid, such as liquid water from water supply  190 , flows though Venturi pump  170 , Venturi pump  170  draws or urges a fluid additive from fluid additive dispensing system  180  into the liquid flowing though Venturi pump  170  in order to form a wash fluid therein. Such wash fluid is directed out of Venturi pump  170  into outlet conduit  174 . 
     Outlet conduit  174  extends between Venturi pump  170  and nozzle  176 . In particular, outlet conduit  174  extends between an entrance  196  and an exit  198 . Entrance  196  of outlet conduit  174  is positioned at or mounted to Venturi pump  170  and is configured for receipt of wash fluid from Venturi pump  170 . Conversely, exit  198  of outlet conduit  174  is positioned at or mounted to nozzle  176  and is configured for directing wash fluid from Venturi pump  170  into nozzle  176 . Outlet conduit  174  can include any suitable mechanism for containing and directing a flow of liquid water therethrough. For example, outlet conduit  174  may include piping, hoses, tubing, combinations thereof, etc. 
     Nozzle  176  is positioned adjacent drum  120  ( FIG. 1 ) and is configured for directing fluid additive from outlet conduit  174  into wash chamber  122  of drum  120 . For example, drum  120  is rotatably mounted within a tub (not shown) of washing machine appliance  100 . The tub is configured for receiving and containing wash fluid during operating of washing machine appliance  100 . Nozzle  176  may be mounted to the tub and positioned above drum  120  such that wash fluid from nozzle  176  falls downwardly towards articles within wash chamber  122  of drum  120 . 
     As may be seen in  FIGS. 2-5 , fluid additive dispensing system  180  includes a tank  182  and an additive conduit  184 . Tank  182  defines a volume  183  for receiving and containing fluid additive therein. Volume  183  can contain any suitable amount of fluid additive. For example, tank  182  may be sized such that volume  183  contains sufficient fluid additive for numerous wash cycles of washing machine appliance  100 . In particular, tank  182  may be sized such that volume  183  contains sufficient fluid additive for about or at least ten, twenty, thirty, fifty or one hundred wash cycles of washing machine appliance  100 . Tank  182  can contain any suitable fluid additive. For example, the fluid additive may include detergent, fabric softener, bleach, etc. 
     Additive conduit  184  extends between tank  182  and Venturi pump  170 . In particular, additive conduit  184  extends between an entrance  186  and an exit  188 . Entrance  186  of additive conduit  184  is positioned at or mounted to tank  182  and is configured for receipt of fluid additive from volume  183  of tank  182 . Conversely, exit  188  of additive conduit  184  is positioned at or mounted to Venturi pump  170  and is configured for directing fluid additive within additive conduit  184  into Venturi pump  170 . In certain exemplary embodiments, entrance  186  of additive conduit  184  is positioned below exit  188  of additive conduit  184 , e.g., along a vertical direction V. In such a manner, gravity can assist with limiting undesired or additional dispensing of fluid additive from fluid additive dispensing system  180  at Venturi pump  170 , e.g., after a flow of liquid from water supply  190  through Venturi pump  170  is terminated or limited. Additive conduit  184  can include any suitable mechanism for containing and directing a flow of liquid water therethrough. For example, additive conduit  184  may include piping, hoses, tubing, combinations thereof, etc. 
     Washing machine appliance  100  also includes a flow meter  162  and a valve  164 . Flow meter  162  may be positioned adjacent or mounted to additive conduit  184 . Flow meter  162  is configured for measuring a flow of fluid through additive conduit  184 . In particular, flow meter  162  may measure a flow rate of the flow of fluid additive through additive conduit  184 . Flow meter  162  can be any suitable mechanism for measuring fluid flow through additive conduit  184 . For example, flow meter  162  may be a mechanical flow meter, a pressure-based flow meter, an optical flow meter, an electrical flow meter, etc. In certain exemplary embodiments, flow meter  162  may be a bidirectional flow meter such that flow meter  162  can measure the flow rate of the flow of fluid additive through additive conduit  184  regardless of the direction of fluid flow through additive conduit  184 . 
     Valve  164  is positioned adjacent or mounted to inlet conduit  172 . Valve  164  is configured for regulating the flow of liquid within inlet conduit  172 . In particular, valve  164  is selectively adjustable between an open configuration and a closed configuration. In the open configuration, valve  164  permits fluid flow through inlet conduit  172 , e.g., such that liquid water from water supply  190  may flow through inlet conduit  172  to Venturi pump  170 . Conversely, valve  164  obstructs or prevents fluid flow through inlet conduit  172 , e.g., such that liquid water from water supply  190  may not flow through inlet conduit  172  to Venturi pump  170 , in the closed configuration. Valve  164  may be any suitable mechanism for regulating or adjusting fluid flow through inlet conduit  172 . For example, valve  164  may be a solenoid valve. 
     As may be seen in  FIGS. 2-5 , washing machine appliance  100  also includes a processing device or controller  160 . Operation of washing machine appliance  100  is regulated or controlled by controller  160 . Controller  160  includes memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of washing machine appliance  100 . The memory can represent random access memory such as DRAM, erasable read/write-once memory such as FLASH, or read only memory such as ROM. The memory can be a separate component from the processor or can 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  is operatively coupled to various components of washing machine appliance  100 . For example, controller  160  is in communication with control panel  110  in order to permit user manipulation of input selectors  112  to select washing machine appliance cycles and features. Thus, in response to user manipulation of control panel  110 , controller  160  operates the various components of washing machine appliance  100  to execute selected machine cycles and features. Controller  160  is also in communication with flow meter  162  and valve  164 . Based at least in part on signals from flow meter  162 , controller  160  can measure the flow rate of fluid additive within additive conduit  184 . For example, voltage or current supplied by flow meter  162  can correspond to the flow rate of fluid additive within additive conduit  184 . 
     Washing machine appliance  100  also includes features for assisting with accurate and/or precise dispensing of fluid additive from fluid additive dispensing system  180 . In particular, washing machine appliance  100  includes features for assisting with accurately and/or precisely dispensing a particular volume of fluid additive with fluid additive dispensing system  180 . Such features can assist with operation of washing machine appliance  100  by facilitating dispensing of a proper volume of fluid additive. Such features can also assist with avoiding waste of fluid additive during operation of washing machine appliance  100 . 
       FIG. 6  provides exemplary plots of a volume of fluid additive within tank  182  of fluid additive dispensing system  180  and a flow rate of fluid through additive conduit  184  of fluid additive dispensing system  180  versus time during an operation of washing machine appliance  100  and fluid additive dispensing system  180 . Operation of washing machine appliance  100  and features of washing machine appliance  100  that assist with accurately and/or precisely dispensing a proper volume of fluid additive with fluid additive dispensing system  180  are discussed in greater detail below with reference to  FIGS. 2, 3, 4, 5 and 6 . As an example of an operation of washing machine appliance  100 , a user can load articles for washing into wash chamber  122  of drum  120 , and the user can initiate washing operation through manipulation of input selectors  112  of control panel  110 . Fluid additive from fluid additive dispensing system  180  can assist with washing the articles within wash chamber  122  of drum  120 . However, fluid additive dispensing system  180  can require priming prior to dispensing fluid additive. 
     In  FIG. 2 , fluid additive dispensing system  180  is shown in a resting operation state. In the resting operation state, valve  164  is in the closed configuration such that liquid water from water supply  190  is hindered from flowing through inlet conduit  172  to Venturi pump  170 . Because liquid is not flowing through Venturi pump  170 , Venturi pump  170  does not draw fluid additive from tank  182  when fluid additive dispensing system  180  in the resting operating state. As may be seen in  FIG. 2 , a height of fluid additive in additive conduit  184  is equal to a height of fluid additive in tank  182 , e.g., due to Venturi pump  170  not drawing fluid additive out of tank  182  via additive conduit  184 . Also, additive conduit  184  contains air above the fluid additive therein. Thus, Venturi pump  170  is unprimed when fluid additive dispensing system  180  is in the resting operation state, and fluid additive dispensing system  180  does not dispense fluid additive from tank  182  into liquid water flowing through Venturi pump  170 . 
     Turning to  FIG. 6 , the exemplary operation of fluid additive dispensing system  180  occurs over a time interval of about twenty five seconds or less. Certain portions of the time interval are labeled A, C, F and G. Such portions of the time interval are discussed in greater detail below with the respect to the corresponding condition of fluid additive dispensing system  180 . In  FIG. 6 , fluid additive dispensing system  180  is in the resting operation state (shown in  FIG. 2 ) during the portion of the time interval before the portion A of the time interval and after the portion G of the time interval. As may be seen in  FIG. 6 , the flow rate of fluid, such as fluid additive from tank  182 , within additive conduit  184  is about zero when fluid additive dispensing system  180  is in the resting operation state, e.g., because Venturi pump  170  is not drawing fluid additive from tank  182  and the height of fluid additive in additive conduit  184  is about equal to the height of fluid additive in tank  182 . Further, the volume of fluid additive within tank  182  is substantially constant when fluid additive dispensing system  180  is in the resting operation state. 
     In  FIG. 3 , fluid additive dispensing system  180  is shown in a priming operation state. In the priming operation state, valve  164  is in the open configuration such that a flow of liquid water from water supply  190  to Venturi pump  170  is initiated. Because liquid is flowing through Venturi pump  170 , Venturi pump  170  begins drawing fluid additive from tank  182  when fluid additive dispensing system  180  in the priming operating state. To adjust fluid additive dispensing system  180  from the resting operation state shown in  FIG. 2  to the priming operation state shown in  FIG. 3 , controller  160  can actuate valve  164  from the closed position to the open position. 
     Controller  160  monitors the flow rate of fluid within additive conduit  184  with flow meter  162  during at least portions A and C of the time interval. In such a manner, controller  160  can determine when Venturi pump  170  primes. As may be seen in  FIG. 3 , the height of fluid additive in additive conduit  184  is not equal to the height of fluid additive in tank  182 , e.g., due to Venturi pump  170  drawing fluid additive out of tank  182  via additive conduit  184 . As may be seen in  FIGS. 2 and 3 , the height of fluid additive in additive conduit  184  in the resting operation state shown in  FIG. 2  is less than the height of fluid additive in additive conduit  184  in the priming operation state shown in  FIG. 3 . Similarly, the height of fluid additive in tank  182  in the resting operation state shown in  FIG. 2  is greater than the height of fluid additive in tank  182  in the priming operation state shown in  FIG. 3 . Additive conduit  184  still contains air above the fluid additive therein in the priming operation state shown in  FIG. 3 . Thus, Venturi pump  170  remains unprimed when fluid additive dispensing system  180  is in the priming operation state. 
     In  FIG. 6 , fluid additive dispensing system  180  is in the priming operation state (shown in  FIG. 3 ) during portion A of the time interval. As may be seen in  FIG. 6 , the flow rate of fluid, such as fluid additive from tank  182 , within additive conduit  184  is about two ounces per second when fluid additive dispensing system  180  is in the priming operation state, e.g., because Venturi pump  170  is drawing air out of additive conduit  184 . The flow rate of fluid within additive conduit  184  is substantially constant while fluid additive dispensing system  180  is in the priming operation state. 
     In  FIG. 4 , fluid additive dispensing system  180  is shown in a primed operation state. In the primed operation state, valve  164  remains in the open configuration such the flow of liquid water from water supply  190  to Venturi pump  170  continues to flow. Because liquid is flowing through Venturi pump  170 , Venturi pump  170  draws or urges fluid additive from tank  182  when fluid additive dispensing system  180  in the primed operating state. With fluid additive dispensing system  180  in the primed operation state, wash fluid, e.g., a mix of liquid water from water supply  190  and fluid additive fluid additive dispensing system  180 , flows from Venturi pump  170  to nozzle  176 . 
     As may be seen in  FIG. 4 , the height of fluid additive in additive conduit  184  is not equal to the height of fluid additive in tank  182 , e.g., due to Venturi pump  170  drawing fluid additive out of tank  182  via additive conduit  184 . As may be seen in  FIGS. 3 and 4 , the height of fluid additive in additive conduit  184  in the priming operation state shown in  FIG. 3  is less than the height of fluid additive in additive conduit  184  in the primed operation state shown in  FIG. 4 . Similarly, the height of fluid additive in tank  182  in the priming operation state shown in  FIG. 3  is greater than the height of fluid additive in tank  182  in the primed operation state shown in  FIG. 4 . Further, additive conduit  184  does not contain air in the primed operation state shown in  FIG. 4 . Thus, Venturi pump  170  is primed when fluid additive dispensing system  180  is in the primed operation state such that fluid additive dispensing system  180  dispenses fluid additive from tank  182  into liquid water flowing through Venturi pump  170  in order to form wash fluid within Venturi pump  170 . Such wash fluid is directed to nozzle  176  and into wash chamber  122  of drum  120  through outlet conduit  174  from Venturi pump  170 . 
     In  FIG. 6 , fluid additive dispensing system  180  is in the primed operation state (shown in  FIG. 4 ) during portion C of the time interval. As may be seen in  FIG. 6 , the flow rate of fluid, such as fluid additive from tank  182 , within additive conduit  184  is about one ounce per second when fluid additive dispensing system  180  is in the primed operation state, e.g., because Venturi pump  170  is drawing fluid additive out of additive conduit  184 . The flow rate of fluid within additive conduit  184  is substantially constant while fluid additive dispensing system  180  is in the primed operation state. The flow rate of fluid within additive conduit  184  when fluid additive dispensing system  180  is in the primed operation state is less than the flow rate of fluid within additive conduit  184  when fluid additive dispensing system  180  is in the priming operation state, e.g., due to viscosity difference and/or other physical property differences between air and the fluid additive. 
     Controller  160  measures a volume of fluid additive dispensed at Venturi pump  170  after the flow rate of fluid additive flowing through additive conduit  184  to Venturi pump  170  decreases by a substantial amount or at least a predetermined amount (shown with arrow B) and, e.g., fluid additive dispensing system  180  switches between the in the priming and primed operation states. In such a manner, controller  160  can determine when air within additive conduit  184  is discharged and fluid additive within additive conduit  184  reaches Venturi pump  170 . After fluid additive reaches Venturi pump  170 , controller  160  monitors the flow rate of fluid within additive conduit  184  in order to determine a volume of fluid additive dispensed at Venturi pump  170 . Thus, during portion C of the time interval, controller  160  can utilize the flow rate of fluid through additive conduit  184  from flow meter  162  to calculate the volume of fluid additive dispensed at Venturi pump  170  (shown with arrow E) as will be understood by those skilled in the art. 
     The predetermined amount can be any suitable value. For example, the predetermined amount may be about five ounces per second, about ten ounces per second, about fifteen ounces per second, about twenty ounces per second, etc. The predetermined value may be selected in order to permit controller  160  to determine when fluid additive dispensing system  180  switches between the priming and primed operation states. Thus, because air flows more easily into Venturi pump  170 , the predetermined amount can be selected in order to permit controller  160  to detect when fluid additive within additive conduit  184  reaches Venturi pump  170 . As will be understood by those skilled in the art, the predetermined value can vary depending upon the viscosity and other physical properties of the fluid additive within tank  182  and additive conduit  184 . 
     Once drum  120  is properly filled with wash fluid, controller  160  operates or adjusts valve  164  to the closed configuration in order to hinder the flow of liquid water to Venturi pump  170 , e.g., after a predetermined volume of fluid additive has been dispensed at Venturi pump  170  from fluid additive dispensing system  180 . Articles within wash chamber  122  of drum  120  are agitated with ribs  126  by rotating drum  120 . After the agitation phase of the wash cycle is completed, wash fluid is drained from drum  120 . Articles can then be rinsed by adding relatively clean fluid to drum  120 , depending on the particulars of the cleaning cycle selected by a user, ribs  126  may again provide agitation within wash chamber  122 . One or more spin cycles may also be used. In particular, a spin cycle may be applied after the wash cycle and/or after the rinse cycle in order to wring wash fluid from the articles being washed. During a spin cycle, drum  120  is rotated at relatively high speeds. 
     In  FIG. 5 , fluid additive dispensing system  180  is shown in a settling operation state. In the settling operation state, valve  164  is in the closed configuration such that liquid water from water supply  190  is hindered from flowing through inlet conduit  172  to Venturi pump  170 . Because liquid is not flowing through Venturi pump  170 , Venturi pump  170  does not draw fluid additive from tank  182  when fluid additive dispensing system  180  in the settling operating state. Further, the height fluid additive within additive conduit  184  that is above the height of fluid additive in tank  182 . Thus, gravity draws or urges fluid additive within additive conduit  184  back into tank  182  until the height fluid additive within additive conduit  184  is about equal to the height of fluid additive in tank  182 , e.g., and fluid additive dispensing system  180  is in the resting operation state. In addition, gravity can also draw or urge wash fluid from Venturi pump  170  into additive conduit  184  when fluid additive dispensing system  180  is in the resting operation state. 
     In  FIG. 6 , fluid additive dispensing system  180  is in the settling operation state (shown in  FIG. 5 ) during portion G of the time interval. As may be seen in  FIG. 6 , the flow rate of fluid, such as fluid additive from tank  182 , within additive conduit  184  varies and settles to zero when fluid additive dispensing system  180  is in the settling operation state, e.g., as the height fluid additive within additive conduit  184  approaches the height of fluid additive in tank  182 . In  FIG. 6 , flow meter  162  is a bidirectional flow meter, e.g., such that measurements of flow meter  162  are positive despite the direction of flow within additive conduit  184 . 
     Controller  160  can measure the flow rate of fluid additive within additive conduit  184  after valve  164  is closed and fluid additive dispensing system  180  switches from the primed operating state ( FIG. 4 ) to the settling operation state ( FIG. 5 ). Thus, during portion G of the time interval, controller  160  can utilize the flow rate of fluid additive through additive conduit  184  from flow meter  162  to calculate the volume of fluid additive flowing into tank  182  from additive conduit  184  (shown with arrow D). Based upon a volume of fluid additive returning to tank  182  when fluid additive dispensing system  180  is in the settling operation state, controller  160  can determine the height of fluid additive in tank  182  (e.g., if a cross-sectional area of tank  182  is known) and/or the volume of fluid additive in tank  182 . 
     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.