Patent Publication Number: US-8968486-B2

Title: Rinse aid release detection method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application represents a divisional application of U.S. patent application Ser. No. 12/582,789 entitled “RINSE AID RELEASE DETECTION METHOD” filed Oct. 21, 2009, currently allowed. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a dishwashing machine and more particularly to a mechanism and method of detecting the release of rinse aid into a dishwashing cycle. 
     BACKGROUND 
     A dishwashing machine is a domestic appliance into which dishes and other cooking and eating wares (e.g., plates, bowls, glasses, flatware, pots, pans, bowls, and etcetera) are placed to be washed. A dishwasher includes a number of dish racks which support such wares. Some dishwashers employ a rinse chemistry which includes a rinse aid during a dishwashing cycle. 
     SUMMARY 
     According to one aspect, a dishwashing machine is disclosed. The dishwashing machine includes a tub defining a washing chamber, a number of dish racks positioned in the washing chamber, and a pump operable to circulate fluid onto the number of dish racks during a dishwashing cycle. The dishwashing machine also includes a turbidity sensor operable to measure turbidity of fluid in the washing chamber and generate an electrical output signal indicative thereof, and an electronic controller electrically coupled to the turbidity sensor. The electronic controller includes a processor and a memory device electrically coupled to the processor. The memory device has stored therein a plurality of instructions which, when executed by the processor, cause the processor to communicate with the turbidity sensor to determine a turbidity level of fluid in the washing chamber, determine presence of a rinse aid in fluid in the washing chamber based on the turbidity level, and modify a drying stage of the dishwashing cycle when rinse aid is present in the fluid. 
     In some embodiments, the dishwashing machine may further include an electronically-controlled dispenser electrically coupled to the controller. The dispenser may have a receptacle formed therein configured receive the rinse aid and a hatch extending over an opening defined in a front surface of the receptacle. The plurality of instructions stored in the memory device, when executed by the processor, may further cause the processor to operate the dispenser to open the hatch such that the rinse aid may pass from the dispenser into the washing chamber. 
     In some embodiments, the plurality of instructions, when executed by the processor, may further cause the processor to communicate with the turbidity sensor to determine a first turbidity level before the dispenser is operated to open the hatch, communicate with the turbidity sensor to determine a second turbidity level after the dispenser is operated to open the hatch, and calculate a difference between the second turbidity level and the first turbidity level. Additionally, in some embodiments, the plurality of instructions, when executed by the processor, may further cause the processor to determine the rinse aid is present when the difference between the second turbidity level and the first turbidity level is greater than a predetermined threshold value. 
     In some embodiments, the dishwashing machine may further include an electric heating element electrically coupled to the controller. The electric heating element may be configured to heat fluid in the washing chamber. The plurality of instructions, when executed by the processor, may further cause the processor to operate the electric heating element to heat fluid in the washing chamber to a first temperature and communicate with the turbidity sensor to determine the turbidity level of fluid in the washing chamber at the first temperature. 
     In some embodiments, the turbidity sensor may be an optical water indicator sensor. Additionally, in some embodiments, the dishwashing machine may further include a lower spray arm positioned below one of the number of dishracks that is fluidly coupled to the pump to circulate fluid, and an upper spray arm positioned above the lower spray arm that is fluidly coupled to the pump to alternately circulate fluid with the lower spray arm. The dishwashing machine may include a diverter valve electrically coupled to the controller and configured to alternately supply fluid to the upper spray arm and the lower spray arm. The plurality of instructions, when executed by the processor, may further cause the processor to operate the diverter valve to suspend the supply of fluid to the lower spray arm such that the upper spray arm continuously circulates fluid, communicate with the turbidity sensor to determine the first turbidity level and second turbidity level while the upper spray arm continuously circulates fluid, and operate the diverter valve to resume the supply of fluid to the lower spray arm such that the lower spray arm alternately circulates fluid with the upper spray arm. 
     According to another aspect, a method of detecting a rinse aid in a dishwashing cycle is disclosed. The method includes determining a first turbidity level of fluid in a washing chamber during a rinsing stage of a dishwashing cycle, generating a control signal to operate a dispenser during the rinsing stage, determining a second turbidity level of fluid in the washing chamber after generation of the control signal, determining if a rinse aid is present in fluid in the washing chamber based on the first turbidity level and the second turbidity level, and selecting a drying stage of the dishwashing cycle based on whether the rinse aid is present. In some embodiments, determining if the rinse aid is present may include comparing the second turbidity level to the first turbidity level and concluding the rinse aid is not present if the second turbidity level is less than the first turbidity level. 
     Additionally, in some embodiments, determining if the rinse aid is present may include determining whether the second turbidity level is greater than or equal to the first turbidity level, calculating a difference between the second turbidity level and the first turbidity level when the second turbidity level greater than or equal to the first turbidity level, and concluding the rinse aid is present when the difference between the second turbidity level and the first turbidity level exceeds a predetermined threshold value. In some embodiments, selecting the drying stage of the dishwashing cycle may include selecting a standard drying stage having a standard duration and a standard temperature if the rinse aid is not present in fluid. 
     In some embodiments, selecting the drying stage of the dishwashing cycle may include selecting a modified drying stage having a duration less than the standard duration when the rinse aid is present in fluid. Additionally, in some embodiments, selecting the drying stage of the dishwashing cycle may include selecting a modified drying stage having a temperature less than the standard temperature when the rinse aid is present in fluid. 
     In some embodiments, the method may include supplying fluid to an upper spray arm and a lower spray arm such that the upper spray arm and the lower spray arm alternately circulate fluid in a washing chamber, suspending the supply of fluid to the lower spray arm before determining the first turbidity level such that fluid is circulated continuously from the upper spray arm, and resuming the supply of fluid to the lower spray arm after determining the second turbidity level. 
     According to another aspect, a method of operating a dishwashing machine is disclosed. The method includes heating fluid in the washing chamber to a first temperature during a rinsing stage of a dishwashing cycle, opening a rinse aid dispenser of the dishwashing machine at a predetermined time during the rinsing stage, determining if a rinse aid is present in the fluid in the dishwashing machine based on a first turbidity level and a second turbidity level subsequent to opening the rinse aid dispenser, heating the fluid in the washing chamber to a second temperature subsequent to opening the rinse aid dispenser, and completing the rinsing stage at the second temperature. In some embodiments, the method may further include adjusting a drying stage of the dishwashing cycle if the rinse aid is present in fluid in the dishwashing machine. 
     Additionally, in some embodiments, the method may further include determining the first turbidity level with an optical water indicator sensor prior to opening the rinse aid dispenser, and determining the second turbidity level with the optical water indicator sensor subsequent to opening the rinse aid dispenser. In some embodiments, determining if a rinse aid is present in fluid may include comparing a first turbidity level to a second turbidity level, and concluding the rinse aid is present when the second turbidity level exceeds the first turbidity level by a predetermined threshold value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description particularly refers to the following figures, in which: 
         FIG. 1  is a perspective view of a dishwashing machine; 
         FIG. 2  is a simplified block diagram of one illustrative embodiment of a control system for the dishwashing machine of  FIG. 1 ; 
         FIG. 3  is a simplified flow chart of a control routine for detecting rinse aid in fluid in a dishwashing machine; and 
         FIG. 4  is a simplified flow chart of a control routine for operating a dishwashing machine and detecting rinse aid in fluid in the dishwashing machine. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     The present disclosure relates to a method for detecting the release of rinse aid into a rinse stage of a dishwashing cycle. By use of the term “dishwashing cycle,” it is meant the operation of a dishwasher upon a set of soiled wares that produces a set of cleaned wares, starting with user activation, then proceeding continuously without the need for user intervention, and including at least one washing stage and at least one rinsing stage. A washing stage involves the application of a wash chemistry, typically water and detergent, to remove soils from the wares. A rinsing stage involves the application of a rinse chemistry, typically water and rinse aid, to remove the wash chemistry and prepare the wares for drying. A dishwashing cycle may optionally include other stages, such as a drying stage in which heat is applied after the rinsing stage. A dishwashing cycle may be interrupted by a user, such as by opening a door of the dishwasher, thereby causing the dishwashing cycle to pause until the door is closed. However, without such user intervention, the dishwashing cycle will proceed continuously. 
     At the completion of a dishwashing cycle, a user will remove the set of cleaned wares, either immediately or after a period of time. The period between the dishwashing cycles of the dishwasher thus begins when the user removes a set of cleaned wares from the dishwasher and ends when the user activates a subsequent dishwashing cycle. 
     Referring to  FIG. 1 , a dishwashing machine  10  (hereinafter dishwasher  10 ) is shown. The dishwasher  10  has a tub  12  that defines a washing chamber  14  into which a user may place dishes and other cooking and eating wares (e.g., plates, bowls, glasses, flatware, pots, pans, bowls, etc.) to be washed. The dishwasher  10  includes a number of racks  16  located in the tub  12 . An upper dish rack  16  is shown in  FIG. 1 ; although a lower dish rack is also included in the dishwasher  10 . A number of roller assemblies  18  are positioned between the dish racks  16  and the tub  12 . The roller assemblies  18  allow the dish racks  16  to extend from and retract into the tub  12 , thereby facilitating the loading and unloading of the dish racks  16 . The roller assemblies  18  include a number of rollers  20  that move along a corresponding support rail  22 . 
     A door  24  is hinged to the lower front edge of the tub  12 . The door  24  permits user access to the tub  12  to load and unload the dishwasher  10 . The door  24  also seals the front of the dishwasher  10  during a dishwashing cycle. A control panel  26  is located at the top of the door  24 . The control panel  26  includes a number of controls  28 , such as buttons and knobs, which are used to control the operation of the dishwasher  10 . A handle  30  is also included on the door  24 . The user may use the handle  30  to unlatch the door  24  such that the door  24  may be opened. 
     A machine compartment  32  is located below the tub  12 . The machine compartment  32  is sealed from the tub  12 . In other words, unlike the tub  12 , which is filled with fluid and exposed to spray during the dishwashing cycle, the machine compartment  32  does not fill with fluid and is not exposed to spray during the operation of the dishwasher  10 . The machine compartment  32  houses components such as the dishwasher&#39;s water pump(s) and valve(s), along with the associated wiring and plumbing. It should be noted that, although  FIG. 1  depicts a dishwasher  10  installed in a kitchen cabinet, portable dishwashers, which may be removably connected to a faucet, are also contemplated. 
     Referring now to  FIG. 2 , the dishwasher  10  is shown in a simplified block diagram. A sidewall of the tub  12  includes a water inlet  40 . The water inlet  40  directs water received from an external water source  42  (e.g., house water supply, kitchen faucet, etcetera) into the washing chamber  14 . A water inlet valve  44  positioned between the external water source  42  and the water inlet  40  may be selectively opened or closed to control the flow of water through the water inlet  40 . In some embodiments, the water inlet valve  44  may be an electromechanical valve, such as a solenoid-controlled valve, which opens and closes in response to a control signal. 
     The dishwasher  10  further includes a sump  50  which is formed (e.g., stamped) into a bottom wall  52  of the tub  12 . In particular, the sump  50  defines a reservoir that extends downwardly in a direction away from the washing chamber  14 . The bottom wall  52  of the tub  12  has a sloped configuration that directs the wash chemistry or the rinse chemistry into the sump  50 . The sump  50  is connected to an external drain  54  (e.g., house sewer line, kitchen sink, etcetera). A drain pump  56  is positioned between the sump  50  and the external drain  54 . A control signal may selectively energize the drain pump  56  to drain fluids from the sump  50  or de-energize (turn off) the drain pump  56  to retain fluids in the sump  50 . In other embodiments, an electromechanical valve, such as a solenoid-controlled valve, that opens and closes in response to a control signal may be used in place of drain pump  56 . 
     A wash pump  60  located in the machine compartment  32  is operable to circulate fluids in the sump  50  onto the dish racks  16  (not shown in  FIG. 2 ). The wash pump  60  is fluidly coupled to a lower rotating spray arm  62  and an optional upper rotating spray arm  64  through a diverter valve  66 . The spray arms  62 ,  64  are configured to spray water and/or wash chemistry onto the dish racks  16  (and hence any wares positioned thereon). It should also be appreciated that the dishwashing machine  10  may include other spray arms positioned at various locations in the tub  12 . As shown in  FIG. 2 , the spray arms  62 ,  64  have a number of nozzles  68 . In operation, the wash pump  60  is selectively energized to supply fluid from the sump  50  through diverter valve  66  to one of the spray arms  62 ,  64 , where the fluid is then expelled out one of the nozzles  68 . 
     The diverter valve  66  is positioned between the spray arms  62 ,  64  and the wash pump  60 . The diverter valve  66  is configured to divert the supply of fluid from wash pump  60  to the lower spray arm  62  and the upper spray arm  65 . When placed in one position, the diverter valve  66  causes fluid to be supplied to the lower spray arm  62 . When placed in another position, fluid is supplied to the upper spray arm  64 . In that way, the diverter valve  66  allows fluid to be alternately supplied to each of the spray arms  62 ,  64 , and only one of the spray arms  62 ,  64  sprays fluid onto the dishracks  16  at any given moment during the dishwashing cycle. In some embodiments, the diverter valve  66  may be locked in position such that fluid is supplied only to the upper spray arm  64 , which continuously sprays fluid onto the dishracks  16 . 
     The dishwasher  10  also includes a rinse aid dispenser  70  that operates to introduce a rinse aid, typically in either liquid or gel form, into the washing chamber  14 . A “rinse aid” may include a surface acting agent (also known as a surfactant), one or more sanitizing chemicals (such as bleach, for example), or both, and may contain other chemistries. A rinse aid may be a single mixture or may be stored as two or more separate components until introduction into the washing chamber  14 . By way of illustrative example, a rinse aid might contain about 66.67% surfactant by volume and about 33.33% bleach by volume. It should be appreciated that embodiments in which the rinse aid includes a surfactant or a sanitizing chemical, but not both, are also contemplated. 
     The rinse aid dispenser  70  includes a receptacle  72  positioned in the washing chamber  14 . The receptacle  72  is sized to receive the rinse aid in gel or tablet form. A hatch  74  extends over the receptacle  72  and is movable between an open position where access is permitted to the receptacle  72  and a closed position where access to the receptacle is blocked. In some embodiments, the rinse aid dispenser  70  may include an electromechanical valve, such as a solenoid-controlled valve, which opens and/or closes the hatch  74  in response to a control signal. When the hatch  74  is moved to the open position, rinse aid is permitted to move out of the receptacle  72  into the washing chamber  14 . Upon introduction, the rinse aid mixes with fluid in the washing chamber  14  to form a rinse chemistry that assists in rinsing the wash chemistry from the wares during a rinsing stage. Applying the rinse chemistry to the wares also improves the drying performance of dishwasher  10  and assists in sanitizing the wares during the drying stage of the dishwashing cycle. 
     An electric heating element  76  is positioned adjacent to the sump  50  and is configured to heat fluid in the sump  50 . During a drying stage of the dishwashing cycle when fluid is not being circulated in the washing chamber  14 , the electric heating element  76  is configured to increase the temperature in the washing chamber  14  to dry the wares positioned therein. It will be appreciated that in other embodiments the electric heating element  76  may be integrated into the sump  50  or may be embodied as one or more electric heating elements. 
     A turbidity sensor  80  is positioned in or adjacent to the washing chamber  14  to monitor the turbidity of fluid in the washing chamber  14 . As embodied in  FIG. 2 , the turbidity sensor  80  is an optical water indicator sensor that provides an indication of fluid clarity at any point during the dishwashing cycle and generates an electrical output signal indicative of the turbidity level of the fluid. The output signal is proportionate to the amount of soil, detergent, or rinse aid present in fluid in the washing chamber  14 . As the amount of soil, detergent, or rinse aid increases, the output signal increases by a proportionate amount. 
     A temperature sensor  86  may be optionally positioned in or adjacent to the washing chamber  14  to measure the temperature of fluid in the washing chamber  14 . The temperature sensor  86  is configured to take a temperature measurement of the fluid in the washing chamber  14  and generate an electrical output signal indicative of that measurement. 
     The dishwasher  10  also includes an electronic control unit (ECU) or “electronic controller”  100 . The electronic controller  100  may be positioned in the door  24  or the machine compartment  32  of the dishwasher  10 . The electronic controller  100  is, in essence, the master computer responsible for interpreting electrical signals sent by sensors associated with the dishwasher  10  and for activating or energizing electronically-controlled components associated with the dishwasher  10 . For example, the electronic controller  100  is configured to control operation of the various components of the dishwasher  10 , including the wash pump  60 , rinse aid dispenser  70 , and inlet valve  44 . The electronic controller  100  also monitors various signals from the control panel  26  and the turbidity sensor  80 . The electronic controller  100  also determines when various operations of the dishwasher  10  should be performed. As will be described in more detail below with reference to  FIGS. 3 and 4 , the electronic controller  100  is operable to control the components of the dishwasher  10  such that the dishwasher  10  detects when rinse aid is in fluid in the washing chamber  14  and adjusts the drying stage of the dishwashing cycle in response thereto. 
     To do so, the electronic controller  100  includes a number of electronic components commonly associated with electronic units utilized in the control of electromechanical systems. For example, the electronic controller  100  may include, amongst other components customarily included in such devices, a processor such as a microprocessor  102  and a memory device  104  such as a programmable read-only memory device (“PROM”) including erasable PROM&#39;s (EPROM&#39;s or EEPROM&#39;s). The memory device  104  is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the microprocessor  102 , allows the electronic controller  100  to control operation of the dishwasher  10 . 
     The electronic controller  100  also includes an analog interface circuit  106 . The analog interface circuit  106  converts the output signals from various sensors (e.g., the turbidity sensor  80 ) into signals which are suitable for presentation to an input of the microprocessor  102 . In particular, the analog interface circuit  106 , by use of an analog-to-digital (A/D) converter (not shown) or the like, converts the analog signals generated by the sensors into digital signals for use by the microprocessor  102 . It should be appreciated that the A/D converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  102 . It should also be appreciated that if any one or more of the sensors associated with the dishwasher  10  generate a digital output signal, the analog interface circuit  106  may be bypassed. 
     Similarly, the analog interface circuit  106  converts signals from the microprocessor  102  into output signals which are suitable for presentation to the electrically-controlled components associated with the dishwasher  10  (e.g., the rinse aid dispenser  70 ). In particular, the analog interface circuit  106 , by use of a digital-to-analog (D/A) converter (not shown) or the like, converts the digital signals generated by the microprocessor  102  into analog signals for use by the electronically-controlled components associated with the dishwasher  10 . It should be appreciated that, similar to the A/D converter described above, the D/A converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  102 . It should also be appreciated that if any one or more of the electronically-controlled components associated with the dishwasher  10  operate on a digital input signal, the analog interface circuit  106  may be bypassed. 
     Thus, the electronic controller  100  may control operation of the dishwasher  10  based the presence of the rinse aid in fluid in the washing chamber  14 . In particular, the electronic controller  100  executes a routine including, amongst other things, a control scheme in which the electronic controller  100  monitors outputs of the sensors associated with the dishwasher  10  to control the inputs to the electronically-controlled components associated therewith. To do so, the electronic controller  100  communicates with the sensors associated with the dishwasher  10  to determine, amongst numerous other things, the temperature of fluid in the washing chamber  14  and the turbidity of fluid in the washing chamber  14 . Armed with this data, the electronic controller  100  performs numerous calculations, either continuously or intermittently, including looking up values in preprogrammed tables, in order to execute algorithms to perform such functions as controlling the drain pump  56  to retain fluid in the sump  50 , determining when to operate the hatch  74  of the rinse aid dispenser  70 , controlling the wash pump  60  to apply fluid the wares positioned in the dishwasher  10 , and so on. 
     As will be appreciated by those of the skill in the art, the dishwasher  10  may include elements other than those shown and described above, such as, by way of example, an additional electric heating element to assist in drying the wares or a filter to remove particulates from the re-circulated wash chemistry or rinse chemistry. The dishwasher  10  may also include a variety of other sensors that monitor conditions within the washing chamber  14 , the sump  50 , and/or other components of the dishwasher  10 . It should also be appreciated that the location of many components (i.e., in the washing chamber  14 , in the machine compartment  32 , in or on the door  24 ) may also be altered. 
     Referring now to  FIG. 3 , an illustrative embodiment of a control routine  200  for detecting rinse aid in fluid of the washing chamber  14  is shown. The routine  200  begins with step  202  in which the controller  100  communicates with the turbidity sensor  80  to determine the turbidity level of fluid after the start of the rinsing stage. In the illustrative embodiment described herein, the turbidity sensor  80  measures the clarity of the fluid and generates a electrical output signal indicative thereof. While step  202  is performed after the start of the rinsing stage of the dishwashing cycle after the sump  50  has been filled with fluid, it may be performed before the wash pump  60  is operated to circulate fluid in the washing chamber  14  or after the wash pump  60  has already begun doing so. Once the turbidity level has been determined, the routine  200  advances to step  204 . 
     In step  204 , the controller  100  operates the rinse aid dispenser  70  to move the hatch  74  to the open position at a predetermined time during the rinsing stage. Opening the hatch  74  permits the rinse aid in the receptacle  72  to advance into the washing chamber  14 . In some embodiments, fluid expelled from the nozzles  68  of the spray arms  62 ,  64  contacts the rinse aid in the receptacle  72  and causes the introduction of the rinse aid into the washing chamber  14 . As discussed above, upon introduction the rinse aid mixes with fluid in the washing chamber  14  to form a rinse chemistry that assists in rinsing the wares during the rinsing stage. Once the hatch  74  has been opened, the routine  200  advances to step  206 . 
     In step  206 , the controller  100  communicates with the turbidity sensor  80  to determine another turbidity level of the fluid in the washing chamber  14 . To do this, the turbidity sensor  80  again measures the clarity of the fluid at a predetermined time after operating the rinse aid dispenser  70  and generates an electrical output signal indicative thereof. Once the additional turbidity level has been determined, the routine  200  advances to step  208 . 
     In step  208 , the controller  100  compares the turbidity level determined after the hatch  74  was opened (i.e., the final turbidity level) to the turbidity level determined before it was opened (i.e., the initial turbidity level). When the final turbidity level is less than the initial turbidity level, the controller  100  concludes that the turbidity measurements have likely been influenced by air bubbles or soil and is unable to determine whether rinse aid has been added to fluid in the washing chamber  14 . As a result, the routine  200  advances to step  210  in which the dishwasher  10  is operated at the conclusion of the rinsing stage in accordance with a standard or default drying stage having standard duration and temperature settings. 
     Returning to step  208 , if the final turbidity level is greater than or equal to the initial turbidity level, the routine  200  advances to step  212 . In step  212 , the controller  100  determines a numerical difference between the final turbidity level and the initial turbidity level and compares that numerical difference to a predetermined threshold value. If the difference is less than the threshold value, the controller  100  concludes that the rinse aid is not present in fluid, and the routine  200  proceeds to step  210 . As discussed above, in step  210  the controller  100  operates the dishwasher  10  in accordance with a standard drying stage. 
     When the difference is greater than or equal to the threshold value, the controller  100  concludes that the rinse aid is present in fluid in the washing chamber  14 , and the routine  200  advances to step  214 . In step  214 , the controller  100  operates the dishwasher  10  to complete the rinsing stage before selecting a modified drying stage in step  216 . 
     As discussed above, the addition of rinse aid to fluid during a rinsing stage improves the drying performance of dishwasher  10  and assists in sanitizing the wares during the drying stage of the dishwashing cycle. As such, when the rinse aid is detected in the washing chamber  14  in step  212 , the controller  100  adjusts the duration and/or temperature of the drying stage. In that way, the overall cycle time, cost, and environmental impact of the dishwashing cycle can be reduced based on the detection of the rinse aid. As such, in step  218 , the controller  100  operates the dishwasher  10  in accordance with a drying stage having a duration that is less than the standard duration setting, a temperature that is less than the standard temperature setting, or some combination of both. 
     Referring to  FIG. 4 , an illustrative control routine (i.e., routine  300 ) for operating the dishwasher  10  is illustrated. Some steps of the routine  300  are substantially similar to those discussed above in reference to the embodiment of  FIG. 3 . Such steps are designated in  FIG. 4  with the same reference numbers as those used in  FIG. 3 . The routine  300  begins with step  302  after the sump  50  has been filled with fluid. In step  302 , the controller  100  operates the electric heating element  76  to heat fluid in the washing chamber  14  to an initial fluid temperature. The initial fluid temperature may be a predetermined temperature selected to assist in creating optimum conditions in the washing chamber  14  for the detection of rinse aid. 
     After the fluid is heated to the initial fluid temperature, the routine  300  advances to step  304 . In step  304 , the controller  100  operates the diverter valve  66  to supply fluid only to the upper spray arm  64 , thereby deactivating the lower spray arm  62 . The routine  300  then advances to steps  202 - 206 , which were described above in reference to  FIG. 3 . As described above, the controller  100  determines an initial turbidity level of fluid in the washing chamber  14  before operating the dispenser  70  to open the hatch  74 . After the hatch  74  is opened, the controller  100  determines a final turbidity level of fluid in the washing chamber  14 . 
     After determining the two turbidity levels, the routine advances to step  306 . In step  306 , the controller  100  operates the diverter valve  66  to alternately supply fluid to both spray arms  62 ,  64 , thereby reactivating lower spray arm  62 . The routine  300  then proceeds to step  308  in which the controller  100  operates the electric heating element  76  to heat fluid in the washing chamber  14  to a final fluid temperature at which the dishwasher  10  completes the rinsing stage. 
     After doing so, the routine  300  proceeds to step  212  and completes the dishwashing cycle in the same manner as described above in regard to  FIG. 3 . In particular, when the rinse aid is present in the fluid in the washing chamber  14 , the controller  100  operates the dishwasher  10  to complete the rinsing stage before selecting, in step  216 , a modified drying stage and operating the dishwasher  10  in accordance therewith. 
     There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatus, and system described herein. It will be noted that alternative embodiments of the method, apparatus, and system of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the method, apparatus, and system that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure as defined by the appended claims.