Methods of reusing liquid in a dishwasher

Methods of operating a dishwasher having a treating chamber, a sump fluidly coupled to the treating chamber, a sprayer for spraying liquid in the treating chamber, a recirculation pump fluidly coupled to the sump and the sprayer to recirculate the sprayed liquid from the sump to the sprayer, and a reuse tank for storing liquid. The methods remove and store liquid that do not include sedimented soil particles.

BACKGROUND OF THE INVENTION

Contemporary dishwashers for use in a typical household include a wash tub for storing utensils during the implementation of a wash cycle within the wash tub for cleaning of the stored utensils. A reuse tank may be provided to store liquid captured from the wash tub during a previous wash/rinse phase of the wash cycle. The stored liquid may be used in the same or subsequent wash cycles.

BRIEF DESCRIPTION OF THE INVENTION

An embodiment of the invention includes a method of operating a dishwasher having a treating chamber, a sump fluidly coupled to the treating chamber, a sprayer for spraying liquid in the treating chamber, a recirculation pump fluidly coupled to the sump and the sprayer to recirculate the sprayed liquid from the sump to the sprayer, and a reuse tank for storing liquid, the method includes supplying liquid to the treating chamber, recirculating the liquid through the treating chamber to form a wash liquid comprising a mixture of the liquid and the soil particles. The recirculation may be ceased to allow any sediment soil particles to settle in a lower portion of the sump and the wash liquid may be removed from the sump at a removal location in the sump above the sedimented soil particles and stored.

Another embodiment of the invention includes a method of operating a dishwasher having a treating chamber, a sump fluidly coupled to the treating chamber, a sprayer for spraying liquid in the treating chamber, a recirculation pump fluidly coupled to the sump and the sprayer to recirculate the sprayed liquid from the sump to the sprayer, and a reuse tank for storing liquid, the method includes supplying liquid to the treating chamber, recirculating the liquid through the treating chamber to form a wash liquid comprising a mixture of the liquid and the soil particles. The recirculation may be paused until the wash liquid forms at least a first portion primarily containing sedimented soil particles and a second portion primarily containing entrained soil particles, with the second portion being above the first portion. The wash liquid may be removed from the sump at a removal location in the sump corresponding to the second portion and stored.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1is a schematic, side view of a treating appliance according to a first embodiment of the invention, which is illustrated in the context of a dishwasher10. While the illustrated treating appliance is a dishwasher10, other treating appliances are possible, non-limiting examples of which include other types of dishwashing units, such as in-sink dishwashers, multi-tub dishwashers, or drawer-type dishwashers. The dishwasher10, which shares many features of a conventional automated dishwasher, will not be described in detail herein except as necessary for a complete understanding of the invention.

The dishwasher10may have a cabinet12defining an interior, which is accessible through a door13. The cabinet12may comprise a chassis or frame to which panels may be mounted. For built-in dishwashers, the outer panels are typically not needed. At least one wash tub14is provided within the interior of the cabinet12and defines a treating chamber16to receive and treat utensils according to a cycle of operation, often referred to as a wash cycle whether or not washing occurs. The wash tub14has an open face that is closed by the door13.

For purposes of this description, the term “utensil(s)” is intended to be generic to any item, single or plural, that may be treated in the dishwasher10, including, without limitation; dishes, plates, pots, bowls, pans, glassware, and silverware.

One or more utensil racks, such as a lower utensil rack18and an upper utensil rack20may be provided in the treating chamber16. The racks18,20hold utensils (not shown) that may be treated in the treating chamber16. The racks18,20may be slid in and out of the treating chamber16through the opening closed by the door13.

A detergent dispenser21may be located in the door13. It will be understood that depending on the type of dishwasher and the type of detergent used, the detergent dispenser21may be incorporated into one dispensing mechanism. The detergent dispenser21may be of a single use dispenser type or a bulk dispenser type. In the case of bulk dispensing, the detergent and/or rinse aid can be selectively dispensed into the treating chamber16in a regulated quantity and at a predetermined time or multiple times during a cycle of operation.

A liquid supply system is provided for supplying liquid to the treating chamber16as part of a wash cycle for washing any utensils within the racks18,20. The liquid supply system includes one or more liquid sprayers, which are illustrated in the form of spray arm assemblies22,24,26, that are provided within the treating chamber16and are oriented relative to the racks18,20such that liquid sprayed from the spray arm assemblies22,24,26may be directed into one or more of the racks18,20.

It should be noted that the stacked arrangement of the utensil racks and the spray arm assemblies is not limiting to the invention. It merely serves to illustrate the invention. For example, the invention may be implemented in a stacked arrangement having a silverware basket, the lower and upper utensil rack, and with upper, middle, and lower level spray arm assemblies having spray heads for the silverware basket alternatively arranged in between the lower and upper utensil rack.

The liquid supply system further comprises a sump30to collect by gravity, liquid sprayed within the treating chamber16. The sump30is illustrated as being formed with or affixed to a lower portion of the wash tub14to collect liquid that may be supplied into or circulated in the wash tub14during, before, or after a cycle of operation. However, the sump30may be remote from the wash tub14and fluidly coupled by suitable fluid conduits.

The liquid supply system further comprises a pump assembly32fluidly coupled to the sump30, and as illustrated, may include a wash pump or recirculation pump34and a drain pump36. The recirculation pump34fluidly couples the sump30to the spray arm assemblies22,24,26through a spray arm supply conduit37to recirculate liquid that collects in the sump to the spray arm assemblies22,24,26for spraying on the racks18,20. The drain pump36fluidly couples the sump30to a drain conduit62for draining liquid collected in the sump30to a household drain, such as a sewer line, or the like.

The liquid supply system further comprises a reuse tank52for storing liquid captured during one or more phases/steps of a wash cycle for later use in the current wash cycle and/or a subsequent wash cycle. The reuse tank52may be fluidly coupled to the recirculation pump34by a reuse tank supply conduit50so that liquid from the sump30may be supplied to the reuse tank52. A control valve48controls the liquid from the recirculation pump34to either the spray arm supply conduit37or the reuse tank supply conduit50. The reuse tank52may also be fluidly coupled to the sump30by an outlet conduit51such that liquid in the reuse tank52may be supplied to the sump30for subsequent use. A control valve56is provided in the outlet conduit51to control the supply of liquid from the reuse tank52to the sump30. A supply conduit64may fluidly couple the reuse tank52to the drain pump36through a drain conduit62and a control valve63. The control valve63is provided to control the flow of liquid from the drain pump36to either the drain conduit62or the reuse tank52.

As illustrated, the physical relationship between the reuse tank52and the sump30uses gravity to supply the liquid from the reuse tank52to the sump30. Thus, liquid from the sump30may be supplied to the reuse tank52by either combination of recirculation pump34, control valve56, outlet conduit51or drain pump36, control valve63, supply conduit64, and valve65. With either configuration, the actuation of the corresponding control valve48,63will redirect the output of the recirculation pump34or drain pump36, respectively, to the reuse tank52, through the corresponding conduit50,64and the valve65. However, it is contemplated that the reuse tank52may be provided at other locations, some of which may be incapable of using gravity to supply the reuse liquid to the sump. Thus, it is contemplated that a pump could be provided to pump liquid from the reuse tank52to the sump30, regardless of whether gravity can be used to supply the reuse liquid.

While liquid may be provided to the reuse tank52through the wash tub14and the sump30, the liquid may be directly provided to the reuse tank52. For example, liquid having at least one of water, detergent, and treatment aid may be separately provided in the reuse tank52to form the liquid. Alternatively, premixed mixture having at least one of water, detergent, and treatment aid may be directly provided in the reuse tank52to clean the reuse tank52.

It is noted that the supplying of liquid from the sump30to the reuse tank52may be reiterated multiple times for the multiple wash/rinse phases of a cycle of operation until multiple capture steps may provide enough amount of liquid which is sufficient to fill up the reuse tank52while only one time capturing step during any wash/rinse phase may be performed. It is also noted that whole amount of liquid for any wash/rinse phase during a cycle of operation may be captured to the reuse tank52through either the recirculation pump34or drain pump36while only a portion of the liquid in the wash tub14may be captured and provided to the reuse tank52.

Further as illustrated, the liquid in the reuse tank52may be drained by supplying the liquid to the sump30and then actuating the drain pump36. It is contemplated that a separate drain conduit (not shown) can be provided from the reuse tank52to the drain pump36to directly drain the liquid in the reuse tank without the liquid entering the sump.

While the pump assembly32may include the recirculation pump34and the drain pump36, in an alternative embodiment, the pump assembly32may include a single pump, which may be operated to supply liquid to either the drain conduit62or the spray arm support conduit37, such as by rotating in opposite directions or by valves.

The liquid supply system further comprises a water supply conduit58fluidly coupling a water supply to the sump30. A control valve59controls the flow of water from the household supply to the sump30.

The dishwasher10further comprises a control system having various components and sensors for controlling the flow and condition of the liquid to implement a wash cycle. The control system includes a heater38that may be located within the sump30to selectively heat liquid collected in the sump30. The heater38may be an immersion heater in direct contact with liquid in the sump30to provide the liquid with predetermined heat energy. A temperature sensor such as a thermistor42may be provided in the sump30to provide an output that is indicative of the temperature of any fluid, liquid or air, in the sump30. A pH sensor44may also be located near the bottom of the wall or in the sump30and provide an output indicative of the pH of the liquid in the sump30. A turbidity sensor71may also be located in the sump30, near the bottom of the wall, or near the pump assembly32and provide an output that is indicative of the turbidity of the liquid in the sump30.

The control system may further comprise a heater66provided in the reuse tank52to heat the liquid in the reuse tank52. A thermistor68may be provided in the reuse tank and output a signal indicative of the temperature within the reuse tank52. Similar to the heater38, the heater66may also be in a direct fluid contact with liquid in the reuse tank52to provide heat energy to the liquid stored in the reuse tank52. The thermistor68may be positioned such that the thermistor68may be in direct fluid contact with liquid in the reuse tank52during measurement. A pH sensor70may be coupled to the reuse tank52to output a signal indicative of the pH of liquid in the reuse tank52. Additional sensors may be operably coupled to the reuse tank to monitor the characteristics of liquid in the reuse tank52.

It is also noted that additional sensors may be fluidly coupled to the wash tub14or reuse tank52to provide output indicative of condition of the liquid. Non-limiting examples of additional sensors include a turbidity sensor and a conductivity sensor.

The control system may further comprise a controller40for implementing one or more cycles of operation. As seen inFIG. 2, the controller40is operably coupled to the pumps34,36, heaters38,66, control valves48,56,59,63,65, thermistors42,68, pH sensors44,70, and a turbidity sensor71to either control these components and/or receive their input for use in controlling the components. The controller40is also operably coupled to a user interface72to receive input from a user for the implementation of the wash cycle and provide the user with information regarding the wash cycle. In this way, the controller40can implement a wash cycle selected by a user according to any options selected by the user and provide related information to the user.

The controller40may also comprise a central processing unit (CPU)80and an associated memory82where various wash cycles and associated data, such as look-up tables, algorithms, may be stored. Non-limiting examples of treatment cycles include normal, light/china, heavy/pots and pans, and rinse only. One or more software applications, such as an arrangement of executable commands/instructions may be stored in the memory and executed by the CPU80to implement the one or more wash cycles. The controller40may further include a clock84. The clock84may be alternatively located in another component operably coupled to the controller40.

The user interface72provided on the dishwasher10and coupled to the controller40may include operational controls such as dials, lights, knobs, levers, buttons, switches, and displays enabling the user to input commands to the controller40and receive information about the selected treatment cycle. The user interface72may be used to select a treatment cycle to treat a load of utensils. Alternatively, the treatment cycle may be automatically selected by the controller40based on the soil levels sensed by any sensors in the dishwasher10to optimize the treatment performance of the dishwasher10for a particular load of utensils.

Referring toFIG. 3, the physical phenomena underlying the invention will be described. When recirculation is completed, the wash liquid is drained from the tub14and tends to drain sequentially in three portions, which may be differentiated based on the degree and/or type of soiling. These three portions88,90, and92are schematically illustrated inFIG. 3as layers for ease of description. In reality, the three portions88,90, and92do not form finite layers as the liquid may be swirling or moving around as it is drained.

The first portion88of the wash liquid predominately includes sedimented particles such as sedimented soil deposit portion, sedimented soil particles/solids, deposited particle/solids, or mixture thereof, which may be typically captured by the filter system (not shown) near to the inlet60of the pump assembly32. During the recirculation of the liquid in the treating chamber16, most of the heavy soils, with a density typically greater than the liquid, will not float nor remain entrained in the liquid, but will collect in the sump30and/or at the filter to the recirculation pump34, which is in close proximity to the inlet60to the pump assembly32. Thus, when draining is initiated, the close proximity of these heavy soils to the drain pump36and their tendency to remain as sediments results in the removal of these soils upon the initiating of the draining. Non-limiting examples of the sedimented particles/solids include vegetable, grain, flour dough, or any viscous or gel type food. The second portion90predominately includes recirculated wash liquid that contains particles small enough to pass through the filter system and is considered the “cleanest”, most soil-free, portion of the wash liquid. The third portion92includes lighter soils that may float or easily remain in suspension with the wash liquid. It may also include fine silt that is very slow to drain and may not have ever passed through the filter during recirculation. Non-limiting examples of the third portion92include oil portion, shell bits, husks, or foreign materials such as small piece of plastics.

The second portion90is the preferred portion to capture to the reuse tank52because of its relatively low soil content. The low soil content reduces the likelihood that micro-organisms will grow while the liquid is stored in the reuse tank52. The low soil content also provides cleaner water, capable of greater capacity for carrying more soil from subsequent wash phases or wash cycles.

However, while the second portion90with the lightest soil level is the preferred portion to capture for reuse, its collection can be quite difficult without also collecting some of the first and third portions88,92, having more soils than the second portion90. For example, the volume of liquid being drained is not always consistent. The ratio of the portions to the entire volume and to each other is not always consistent. The amount and type of each of the soils forming each portion may also vary, leading to further variation in the volume of each portion. Thus, it is not always possible to know with certainty the amount of each portion, including the type and amount of soil in each portion.

One solution to capturing the second portion90is to run the drain pump36until the first portion88is drained away through the drain conduit62. As the second portion90is being drained, the output of the drain pump36is diverted by the control valve63to the reuse tank52. Upon the draining of the third portion92, the output of the drain pump36is diverted back to the drain conduit62. During this draining procedure the recirculation pump34may be simultaneously run to ensure that the wash liquid is forced to the drain pump36.

The difficulty with this approach is determining when the draining transitions through the different portions. Two possibilities for determining the transitions are time-based and turbidity/opacity. The time it takes for the portions to drain can be anecdotally determined and stored in the controller40. Similarly, turbidity ranges or values for the different portions may be determined and stored in the controller40. With this information, it is possible to determine the transition between the different portions.

In the time-based approach, the second portion90may be captured using the drain pump36to divert and maintain the output direction for predetermined time periods, in a similar way described above. For example, the drain pump36may be run for a first time period that is sufficient to drain the first portion88via the drain conduit62. While the drain pump36continues to run, the output of the drain pump36is diverted to the reuse tank52for a second time period sufficient to collect the second portion90. After the passing of the second time period, the output of the drain pump36is diverted from the reuse tank52back to the drain line62. The third portion92is then drained for a third time period.

While the predetermined time periods may be empirically determined based on anticipated liquid volumes and soil conditions, this approach runs the risk of under/over-shooting each of the portions if the volumes and soil conditions vary from what was anticipated or for some reason the pump does not pump at the anticipated rate. An adjustment factor may be introduced in determining the time period to ensure capturing of only the second portion90. For example, a capture time shorter than the time to drain the entire second portion90may be determined. Also, the capturing would be delayed until it was safely within the draining of the second portion90. While this would result in not the entire second portion90being captured, it would ensure that only the second portion90is captured.

Alternatively, the turbidity/optical sensors may be used to determine the transitions between portions and operate the drain pump36and capturing a desired portion accordingly. The turbidity sensor71may be placed relative to the drain pump inlet60or may be in the drain pump outlet near the control valve (diverter)63. The turbidity/opacity may be monitored during draining and compared to the predetermined values, which may be ranges, for each of the portions88,90,92. When the turbidity/opacity values indicate that a transition between portions is present, then the output of the drain pump36may be redirected between the drain conduit62and the reuse tank52to capture only liquid from the second portion90.

While the capturing has been described in terms of using the drain pump36, it is within the scope of the invention for the recirculation pump34to be used to capture. The same approaches described for the drain pump36may be used for the recirculation pump34, with variations as needed to accommodate the use of the recirculation pump34. For example, if it is desired to drain away the first and third portions88,92, the drain pump36may be used to drain away the first portion88. When the first time period passes or turbidity indicates the second portion90is present, the drain pump36is shut off while the recirculation pump34is turned on and the control valve48is opened to direct the second portion90to the reuse tank52through the supply conduit50. When the second time period passes or the turbidity indicates the third portion92is present, the recirculation pump34is shut off and the drain pump36is turned on for the third time period to drain away the third portion92.

In some circumstances, it may be possible to use both the recirculation pump34and drain pump36. In this scenario, both the recirculation pump34and drain pump36may operate at the same time. First, the first portion88may be drained through the drain pump36until the passing of the first time period or the turbidity indicates the presence of the second portion90. At that time the control valve48is actuated to direct the flow of liquid from the recirculation pump34to the reuse tank52to capture the second portion90. Upon the passage of the second time period or the turbidity indicates the presence of the third portion92, the control valve48may direct the flow of liquid from the reuse tank52to the treating chamber16until the third portion92is drained.

FIG. 4is a flow chart of the operation of the dishwasher10according to a third embodiment of the invention. The third embodiment provides for capturing the second portion90to the reuse tank52to use the second portion90in the same or subsequent wash cycle. The sequence of steps depicted inFIG. 4is for illustrative purposes only, and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order, additional or intervening steps may be included, or described steps may be divided into multiple steps, without detracting from the invention. The method may be implemented multiple times, either consecutively or intermittently, during, after or before a wash cycle. The method may be incorporated into a cycle of operation for the dishwasher10, such as prior to or as part of any phase of the wash cycle, such as a wash phase, rinse phase, and drying phase. The method may also be a stand-alone cycle. It is noted that the method may be used with or without the utensils placed within the treating chamber16.

The method400may begin at402by supplying liquid to the treating chamber16. The liquid may be directly provided to the treating chamber16by providing water to the sump30in combination with a treating chemistry, such as detergent. Alternatively, water and the treating chemistry may be pre-mixed before the mixture of water and the treating chemistry is provided to the treating chamber16. When the liquid is supplied to the treating chamber16, the liquid may be collected in the sump30due to gravity.

At404, the liquid may be recirculated in the treating chamber16to form a wash liquid. The liquid in the sump30may be recirculated through the spray arm supply conduit37to at least one of the spray arm assemblies22,24,26to provide a spray of liquid to clean the utensils in the utensil racks18,20in the treating chamber16according to a wash cycle. Alternatively, the liquid may recirculate in the treating chamber16through the spray arm supply conduit37without the presence of utensils inside the treating chamber16, to remove any micro-organisms in the spray arm supply conduit37and/or the treating chamber16, or to clean any remaining food soil in the treating chamber16that may have left from the previous wash cycle.

At406, when the recirculation ceases, the wash liquid having food soils, stains or other impurities may drain from the lower portion of the sump30, sequentially in three portions: first88, second90, and third92. The liquid is drained from the sump30by the drain pump36, with the control valve63actuated to direct the output of the drain pump36down the drain conduit62.

At408, all or part of the second portion90is captured from the draining liquid of406. The capturing is accomplished by directing the output of the drain pump36to the supply conduit64feeding the reuse tank52by the actuation of the control valve63until all or a part of the second portion90is captured. After which, the valve63is actuated again to direct the output of the drain pump36back to the drain conduit62, so that the remaining liquid may be drained. The timing of the actuation of the control valve63may be based on either of the previously described time-based or turbidity/opacity methods.

At410, the liquid captured in408may be provided to the reuse tank52for storage, and all or a portion of the liquid stored in the reuse tank52may be used in the same or subsequent cycles of operation. The stored liquid may be supplied back to the treating chamber16by gravity using outlet conduit51and control valve56.

FIG. 5is a flow chart of the operation of the dishwasher10according to a fourth embodiment of the invention. The fourth embodiment of the invention provides for reusing water throughout an entire dishwashing cycle to increase the total amount of water savings. Basically, water is captured and stored for subsequent reuse in at least three different steps within a cycle. The water is preferably filtered prior to entering the reuse tank52, so that water can be re-used throughout the cycle to increase the amount of water savings. Preferable filtration and dilution of the water enable maintaining acceptable wash performance. This water can be used in the subsequent fill and mixed with fresh water to meet the fill volume requirements. This process can be used multiple times within the latest cycle while still meeting wash performance requirements.

An exemplary flowchart is shown inFIG. 5. The sequence of steps depicted inFIG. 5is for illustrative purposes only, and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order, additional or intervening steps may be included, or described steps may be divided into multiple steps, without detracting from the invention. The method may be implemented multiple times, either consecutively or intermittently, during, after or before a wash cycle. The method may be incorporated into a cycle of operation for the dishwasher10, such as prior to or as part of any phase of the wash cycle, such as a wash phase, rinse phase, and drying phase. The method may also be a stand-alone cycle. It is noted that the method may be used with or without the utensils placed within the treating chamber16.

The method500may begin at502by supplying fresh liquid to the treating chamber16for a first fill. The liquid may be directly provided to the treating chamber16by providing water to the sump30in combination with a treating chemistry, such as detergent. Alternatively, water and the treating chemistry may be pre-mixed before the mixture of water and the treating chemistry is provided to the treating chamber16. When the liquid is supplied to the treating chamber16, the liquid may be collected in the sump30due to gravity. In the illustrated embodiment, the volume of the fresh liquid in the first fill is 3.9 liters. Alternatively, the first fill at502can comprise a mixture of fresh liquid and reuse liquid from the reuse tank52from a prior cycle, for example, 2.5 liters of reuse liquid and 1.4 liters of fresh liquid. The fresh liquid and/or the reuse liquid can include treating chemistry.

At504, the liquid may be recirculated in the treating chamber16in a first wash phase. The liquid in the sump30may be recirculated through the spray arm supply conduit37to at least one of the spray arm assemblies22,24,26to provide a spray of liquid to clean the utensils in the utensil racks18,20in the treating chamber16according to a wash cycle. Alternatively, the liquid may recirculate in the treating chamber16through the spray arm supply conduit37without the presence of utensils inside the treating chamber16, to remove any micro-organisms in the spray arm supply conduit37and/or the treating chamber16, or to clean any remaining food soil in the treating chamber16that may have left from the previous wash cycle.

At506, when the recirculation ceases, the wash liquid having food soils, stains or other impurities may drain from the lower portion of the sump30by the drain pump36, with the control valve63actuated to direct the output of the drain pump36down the drain conduit62. A first or initial portion is captured from the draining liquid of506by directing the output of the drain pump36to the supply conduit64feeding the reuse tank52by the actuation of the control valve63until a designated amount for the initial portion is captured, after which, the valve63is actuated again to direct the output of the drain pump36back to the drain conduit62, so that most of the remaining liquid may be drained. Preferably some liquid, e.g. 0.5 liters, remains in the treating chamber16for wetting the dishes and the tub. The timing of the actuation of the control valve63may be based on either of the previously described time-based or turbidity/opacity methods. Preferably, the initial portion is not sedimented as in the third embodiment, but simply extracted from the drain liquid for direction to the reuse tank52. Preferably, the initial portion is filtered by the filter system before entering the reuse tank.

At508, the filtered, initial portion is stored in the reuse tank for later reuse within the wash cycle. All or some of the initial portion may be supplied back to the treating chamber16by gravity using outlet conduit51and control valve56when directed by the controller40. In the illustrated embodiment, the volume of the stored initial portion is 2.6 liters.

A second fill commences with supplying fresh liquid at510and the initial portion from the reuse tank52at512to the treating chamber16. In the illustrated embodiment, the volume of the fresh liquid for the second fill is 0.7 liters and the stored initial portion is 2.6 liters for a total second fill of 3.3 liters. Recall that about 0.5 liters remains in the treating chamber from the first fill.

At514, the liquid may be recirculated in the treating chamber16in a second wash phase as directed by the controller40. Additional heating can be applied, for example. At516, substantially all of the liquid may be drained from the treating chamber in preparation for a first rinse. A third fill commences with supplying fresh liquid for a short first rinse at518. In the illustrated embodiment, the volume of the fresh liquid for the third fill is 2.1 liters. At520, the liquid may be recirculated in the treating chamber16in a first short rinse as directed by the controller40.

At522, when the short rinse ceases, the rinse liquid may drain from the lower portion of the sump30by the drain pump36, with the control valve63actuated to direct the output of the drain pump36down the drain conduit62. A second or intermediate portion is captured from the draining liquid of518by directing the output of the drain pump36to the supply conduit64feeding the reuse tank52by the actuation of the control valve63until a designated amount for the intermediate portion is captured, after which, the valve63is actuated again to direct the output of the drain pump36back to the drain conduit62, so that most of the remaining liquid may be drained. Preferably, the intermediate portion is filtered by the filter system before entering the reuse tank.

At524, the filtered, intermediate portion is stored in the reuse tank for later reuse within the wash cycle. All or some of the intermediate portion may be supplied back to the treating chamber16by gravity using outlet conduit51and control valve56when directed by the controller40. In the illustrated embodiment, the volume of the stored intermediate portion is 1.3 liters.

A fourth fill commences with supplying fresh liquid at526and the intermediate portion from the reuse tank52at528to the treating chamber16. In the illustrated embodiment, the volume of the fresh liquid for the fourth fill is 2.1 liters and the stored intermediate portion is 1.3 liters for a total fourth fill of about 3.4 liters. At530, the liquid may be recirculated in the treating chamber16in a second longer rinse as directed by the controller40. Heat may also be applied to the rinse water.

At532, when the second longer rinse ceases, the rinse liquid may drain from the lower portion of the sump30by the drain pump36, with the control valve63actuated to direct the output of the drain pump36down the drain conduit62. At534, a third or final portion is captured from the draining liquid by directing the output of the drain pump36to the supply conduit64feeding the reuse tank52by the actuation of the control valve63until a designated amount for the final portion is captured, after which, the valve63is actuated again to direct the output of the drain pump36back to the drain conduit62, so that most of the remaining liquid may be drained. Preferably, the final portion is filtered by the filter system before entering the reuse tank. In the illustrated embodiment, the volume of the stored final portion is 2.5 liters, available for use in a subsequent cycle. It will be seen that the total amount of liquid saved for reuse in this embodiment is about 6.4 liters.

FIG. 6illustrates a dishwasher600according to a fifth embodiment. The fifth embodiment is similar to the first embodiment; therefore, like parts will be identified with like numerals increased by600, with it being understood that the description of the like parts of the first embodiment applies to the fifth embodiment, unless otherwise noted.

One difference between the dishwasher10and the dishwasher600is that the sump is illustrated as including a separate removal location661. The removal location661is fluidly connected with the recirculation pump634through a conduit673and forms an additional inlet of the recirculation pump634. Such a removal location661may correspond to entrained soil particles upon settling of sediment soil particles. As illustrated more clearly inFIG. 7, the removal location661may correspond to the second portion690, which predominately includes recirculated wash liquid that contains particles small enough to pass through the filter system and is considered the “cleanest,” most soil-free, portion of the wash liquid. It is contemplated that a valve667may be operably coupled with the controller640to selectively allow liquid to enter the conduit673. Further, a valve669may be operably coupled with the controller640to selectively allow liquid to enter the conduit660.

In the illustrated example, the recirculation pump634has two inlets to the sump630, with one of the inlets located at the removal location661. Thus, liquid from the sump630may be supplied to the reuse tank652from the removal location661by operating the valve667, recirculation pump634, control valve648, and valve665. In the illustrated example, the recirculation pump634may be a variable speed pump and may be controlled by the controller to operate at lower speeds when liquid is being removed from the removal location661.

Alternatively, the drain pump636could be used instead of the recirculation pump634. In such a configuration, the removal location661could correspond to an inlet for the drain pump636, and the drain pump636may have two inlets from the sump630. Further, it is contemplated that the recirculation pump634and the drain pump634could be combined as a single pump, with the necessary plumbing and valving, and that in such instance that at least one of the inlets for the single pump may be located at the removal location661.

Regardless of which pump is used, it will be understood that the pump may be a multiple speed pump. The speed of the multispeed pump could be reduced, as compared to the recirculating or draining speeds, when liquid is being withdrawn from the removal location661for subsequent storage and reuse. The reduced pump speed may be selected to withdrawal liquid from the second/intermediate portion690while retarding the mixing of the first/initial and third/final portions688,692with the second portion.

FIG. 8is a flow chart of the operation of the dishwasher600according to a sixth embodiment of the invention. The sixth embodiment provides for removing wash liquid from the sump at a removal location661in the sump above the sedimented soil particles and storing the removed wash liquid in the reuse tank for subsequent use. The sequence of steps depicted inFIG. 8is for illustrative purposes only, and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order, additional or intervening steps may be included, or described steps may be divided into multiple steps, without detracting from the invention. The method may be implemented multiple times, either consecutively or intermittently, during, after or before a wash cycle. The method may be incorporated into a cycle of operation for the dishwasher600or the method may also be a stand-alone cycle.

The method700may begin at702by supplying liquid to the treating chamber616. The liquid may be directly provided to the treating chamber616by providing water to the sump630in combination with a treating chemistry, such as detergent. Alternatively, water and the treating chemistry may be pre-mixed before the mixture of water and the treating chemistry is provided to the treating chamber616. When the liquid is supplied to the treating chamber616, the liquid may be collected in the sump630due to gravity.

At704, the liquid may be recirculated in the treating chamber616with the recirculation pump634to remove soil particles from any utensils within the treating chamber616and to form a wash liquid that includes a mixture of the liquid and the soil particles. This may be accomplished by opening the valve669and allowing the liquid in the sump630to be recirculated through the spray arm supply conduit637to at least one of the spray arm assemblies622,624,626to provide a spray of liquid to clean the utensils in the utensil racks618,620in the treating chamber616.

At706, the recirculating of the wash liquid may be ceased to allow any sedimented soil particles in the wash liquid to settle in a lower portion of the sump630. More specifically, the valve669may be closed and the operation of the recirculation pump634may be stopped to cause the cessation of the recirculation. Upon cessation, sediment soil particles, the heavy soils that typically have a density greater than the liquid, will not float nor remain entrained in the liquid but will settle and collect in the sump630close to the inlet conduit660to the pump assembly632.

At708, wash liquid from above the settled sediment soil particles may be removed. Such wash liquid may be removed by removing wash liquid from the sump630at the removal location661in the sump630, which may reduce the likelihood that sedimented soil particles will be stored in the reuse tank652. The removal of the wash liquid may be terminated prior to suspended soil particles reaching the removal location661. More specifically, removing the wash liquid from the sump630at the removal location661includes operating the recirculation pump634to remove wash liquid from the sump630through the conduit673and directing the output of the recirculation pump634through the valve648to the supply conduit650.

It is contemplated that the removal of the wash liquid from the removal location661may be at a lower volumetric rate than a volumetric rate used for recirculating the liquid. This may be because the recirculation pump634is operated at a lower volumetric flow rate during the removal than it is during recirculation. For example, if the recirculation pump634is a multispeed pump the removal of the wash liquid may include operating the recirculation pump634at a removing speed less than a maximum speed. In this manner the removing speed of the recirculation pump634may be a speed that does not stir up the sedimented soil particles.

At710, the liquid removed in708may be provided to the reuse tank652for storage for subsequent use. It is contemplated that as the wash liquid is removed at708that the wash liquid may be stored at710and that such removal and storage may continue to remove and store all or a part of wash liquid above the settled sediment soil particles. The wash liquid may be provided to the reuse tank652through the operation of the recirculation pump634and by the actuation of the valve665. The timing of the actuation of the recirculation pump634may be based on either of the previously described time-based or turbidity/opacity methods.

All or a portion of the liquid stored in the reuse tank652may be used in the same or subsequent cycles of operation. The stored liquid may be supplied back to the treating chamber616by gravity using outlet conduit651and control valve656. The wash liquid is preferably filtered prior to entering the reuse tank52to maintain acceptable wash performance. After the wash liquid is removed at708, the sedimented soil particles including any remaining wash liquid may be drained from the sump by the drain pump636. The liquid is drained from the sump630by the drain pump636, with the control valve663actuated to direct the output of the drain pump636down the drain conduit662. If there are any suspended soil particles in the wash liquid in the sump630, these too may be drained to the drain conduit662.

It is contemplated that between the ceasing the recirculation at706and the removing wash liquid at708there may be a pause to let the sediment soils settle in a lower portion of the sump630. The pausing may be continued until the wash liquid forms at least a first portion688primarily containing the sedimented soil particles, a second portion690primarily containing entrained soil particles, and a third portion692primarily containing suspended soil particles. The removing of the wash liquid from the sump630is at a removal location661in the sump630below any suspended soil particles in the wash liquid. The removal may be stopped before any of the suspended soil particles enter into the conduit673. It is contemplated that to inhibit the removal of any suspended soil particles that only a portion of the second portion690may be removed.

For example,FIG. 9is a flow chart of the operation of the dishwasher600according to a seventh embodiment of the invention. The method according to the seventh embodiment is similar to that of the sixth embodiment except that at806the recirculating of the wash liquid is paused until the wash liquid forms at least a first portion688primarily containing sedimented soil particles and a second portion690primarily containing entrained soil particles, with the second portion690being above the first portion688. The pausing may be continued to form a third portion692, above the second portion690, which primarily contains suspended soil particles. Then at808, wash liquid corresponding to the second portion690may be removed. Such wash liquid may be removed by removing wash liquid from the sump630at a removal location661in the sump630above the first portion688and this may reduce the likelihood that sedimented soil particles will be stored in the reuse tank652. It is contemplated that the removal of the wash liquid may be at lower volumetric rate than a volumetric rate used for recirculating the liquid. For example, the removing speed may be at a speed that does not mix up the first portion688and the second portion690. At810, the liquid removed in808may be provided to the reuse tank652for storage for subsequent use and this may be done concurrently while the second portion690is being removed from the sump630.

Regardless of whether the recirculation is paused for a period or the recirculation is stopped, the three portions688,690, and692may be separate layers as the sediment in the liquid may settle to form the first portion688and the lighter soils may float or easily remain in suspension with the wash liquid to form the third portion. As the liquid is not drained but instead is removed from the removal location661these layers may maintain their separation.

The embodiments described above provide methods for operating a dishwasher fluidly coupled to a reuse tank. The methods of the embodiments of the invention can advantageously be used when the user may need to save water or any other liquid resources provided to the dishwasher for the subsequent wash/rinse step in the present or next wash cycle. The embodiments described above allow for selectively capturing a portion of the wash liquid having fewer food soil and lower turbidity. By selectively capturing the portion having fewer food soil and lower turbidity in the reuse tank, the possibility that extra contaminants such as food soil can be incorporated into the next wash phase would be greatly minimized when the selectively captured portion in the wash liquid is used in the next wash cycle.

While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims. Further, it will be understood that any features of the above described embodiments may be combined in any manner.