Abstract:
A dishwasher includes a system for conditionally releasing a rinse aid into a washing chamber. The dishwasher includes a dispenser for storing rinse aid, a sensor for detecting a temperature of washing fluid in the washing chamber and a controller operatively coupled to the sensor and the dispenser. The controller, based upon a signal received from the sensor indicating a temperature of the washing fluid, activates the dispenser to release the rinse aid. The controller is programmed to only release the rinse aid when the temperature is above a predetermined threshold value.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention pertains to the art of dishwashers and, more particularly, to a dishwasher having a controller that selectively releases a rinse aid during a rinse cycle based on a temperature of washing fluid in the dishwasher.  
         [0003]     2. Discussion of the Prior Art  
         [0004]     The prior art is replete with dishwashers that employ various techniques to wash a wide range of kitchenware, such as dishes, pots, pans, glasses and the like. The dishwashers perform washing operations that typically employ a number of cycles to wash the kitchenware. In general, the number and type of cycles vary from manufacturer to manufacturer. In addition to standard cycles, e.g., wash, rinse and dry, often times, a dishwasher will have “special” cycles that address particular wash conditions, e.g., heavy soil, light soil, pot scrubber etc. In any event, the cycles are generally divided into steps, each having a particular duration. However, while the number and duration of steps will vary from appliance to appliance, there are certain steps that occur in every washing operation. That is, every washing operation has at least one washing step, during which water is mixed with detergent and directed onto kitchenware to wash away soil, and at least one rinsing step, during which clean water is sprayed onto the kitchenware to remove remaining soil and/or detergent.  
         [0005]     As indicated above, during the washing step, detergent is mixed with water to form a washing fluid. The detergent can simply be placed within the dishwasher and exposed to sprays or jets of water or, alternatively, released from a dispenser. The release of detergent is typically based upon time. That is, at some point after initiation of the washing step, a controller executes a timed release of detergent from the dispenser.  
         [0006]     During the rinsing step, clean water is sprayed onto the kitchenware to wash away any remaining soil and/or washing fluid. Actually, depending on the particular dishwasher, the washing operation may include multiple rinse steps to ensure that all the soil and/or washing fluid is washed away, leaving behind sparkling clean dishes. Following the rinse step, the washing operation enters a drying phase or step where the dishes are allowed to dry, either by the passage of time, or through the introduction of heat into the dishwasher. Unfortunately, after the drying phase, water spots often times remain on the kitchenware. While particularly noticeable on glassware, the water spots can also be present on other kitchenware, such as plates, silverware and the like.  
         [0007]     In order to reduce water spots, many consumers add a rinse aid that is released during one of the rinse steps. In some cases, the rinse aid can be in the form of a tablet that is supported from a dishrack in the dishwasher. However, in most cases, the rinse aid is in the form of a liquid released from a dispenser. That is, at some point during the rinse step, a controller will automatically release the rinse aid from the dispenser. More specifically, as long as there is rinse aid in the dispenser, the controller will release the rinse aid into the washing chamber at a predetermined time during the rinse step. The rinse aid then mixes with the water and is sprayed into the kitchenware in order to reduce spotting. However, adding rinse aid at an inappropriate point can result in improper mixing of the water and rinse aid.  
         [0008]     Based on the above, there exists a need in the art for a dishwasher including a controller that releases rinse aid only at an appropriate point of a rinse cycle. More specifically, there exists a need in the art for a dishwasher that can sense a temperature of washing fluid and release rinse aid at a point in the rinse cycle at which proper mixing of rinse aid and washing fluid will occur.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is directed to a dishwasher having a system for conditionally releasing a rinse aid into a washing chamber. In accordance with the invention, the dishwasher includes a dispenser for storing rinse aid, a sensor for detecting a temperature of water or washing fluid in the washing chamber and a controller operatively coupled to the sensor and the dispenser. The controller, based upon a signal received from the sensor indicating a temperature of the washing fluid, activates the dispenser to release the rinse aid. The controller is programmed to only release the rinse aid when the temperature of the washing fluid is above a predetermined threshold value. That is, the controller will only release the rinse aid if the temperature of the washing fluid is above a cloud point of the rinse aid such that foaming will not occur upon mixing of the rinse aid with the washing fluid.  
         [0010]     Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0011]      FIG. 1  is an upper right, perspective view of a dishwasher incorporating a rinse aid dispensing system constructed in accordance with the present invention, with a door of the dishwasher being in an open position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     With reference to  FIG. 1 , a dishwasher constructed in accordance with the present invention is generally indicated at  2 . As shown, dishwasher  2  includes a tub  5  which is preferably injection molded of plastic or formed from stainless steel so as to include integral bottom, side, rear and top walls  8 - 12  respectively. Within the confines of walls  8 - 12 , tub  5  defines a washing chamber  14  within which soiled kitchenware is adapted to be placed upon shiftable upper and lower racks (not shown). Tub  5  has attached thereto a frontal frame  16  which pivotally supports a door  20  used to seal washing chamber  14  during a washing operation. As shown, door  20  is pivotally supported to frame  16  at a bottom portion  21 . In connection with the washing operation, door  20  is preferably provided with a detergent tray assembly  22  including a detergent dispenser  23  within which a consumer can place liquid, particulate or tabular washing detergent for dispensing at a predetermined portion of a washing operation. In addition, in a manner that will be discussed more fully below, detergent tray assembly  22  also includes a rinse aid dispenser  24  for releasing a rinse aid during another predetermined portion of the washing operation. In any case, door  20  is provided with a liner  25  within which is arranged detergent tray assembly  22 , as well as a vent  26  that allows hot air to escape from washing chamber  14  following a drying operation. Liner  25  also includes a lower lip portion  27  that extends across bottom portion  21  of door  20 .  
         [0013]     Disposed within tub  5  and, more specifically, mounted within a central opening (not shown) in a sump portion  28  of tub  5  is a pump assembly  30 . In the embodiment shown, pump assembly  30  includes a main housing  33 , an annular, radially outermost strainer  36  and a filter guard  39 . Extending about a substantial portion of pump assembly  30 , at a portion raised above bottom wall  8 , is a heating element  44 . In a manner known in the art, heating element  44  preferably takes the form of a sheathed, electric resistance-type heating element. A detailed description of the exact structure and operation of pump assembly  30  does not form part of the present invention and thus will not be described more fully herein. Instead, various known pump arrangements can be employed, such as that disclosed in U.S. Pat. No. 6,997,193 which is incorporated herein by reference.  
         [0014]     In general, pump assembly  30  is adapted to direct washing fluid to at least a lower wash arm  47  and a conduit  51 . As depicted, conduit  51  includes a substantially horizontal lower section  53  extending away from main housing  33  of pump assembly  30 , a vertical section  54 , which generally extends along rear wall  11 , and a generally horizontally extending upper portion (not shown) which leads to an upper wash arm (also not shown). Vertical section  54  has attached thereto a wash fluid diverter (not shown) that engages with a rack mounted wash arm (also not shown). In any case, pump assembly  30  is designed to establish a controlled flow of washing fluid that is sprayed upon kitchenware supported within washing chamber  14  during the washing operation.  
         [0015]     At the completion of the washing operation, pump assembly  30  guides the washing fluid through a drain pump (not shown) having associated therewith a drain hose  85  including at least one corrugated or otherwise curved portion  89  that extends about an arcuate hanger  92  provided on an outside surface of side wall  10 . Drain hose  85  is also preferably secured to tub  5  through various clips, such as that indicated at  95 . In any event, in this manner, an upper loop is maintained in drain hose  85  to ensure proper drainage in a manner known in the art.  
         [0016]     In accordance with the invention, dishwasher  2  includes a controller  100  that is operatively connected to rinse aid dispenser  24 . Controller  100  is also operatively connected to a temperature sensor  104  which is preferably mounted within sump portion  28  of washing chamber  14 . Temperature sensor  104  is positioned so as to detect and signal a temperature of washing fluid circulating within washing chamber  14 . In accordance with the invention, controller  100  will only activate rinse aid dispenser  24 , releasing rinse aid into washing chamber  14 , when a temperature of the washing fluid is at or above a predetermined temperature value. Most preferably, controller  100  will only activate rinse aid dispenser  24  when the temperature of the washing fluid, as sensed by temperature sensor  104 , is above approximately 125° F. (51.7° C.). That is, rinse aid will only be released when the temperature of the washing fluid is above a cloud point of the rinse aid as will be discussed more fully below.  
         [0017]     After loading kitchenware into washing chamber  14 , detergent into detergent dispenser  23  and rinse aid into rinse aid dispenser  24 , a consumer initiates a washing operation in a manner known in the art through user interface  110 . Initially, water is introduced into tub  5  upon opening of a water valve  115 , with the water being sprayed about washing chamber  14  by, for example, wash arm  47  to perform an initial dishware cleansing operation. After a predetermined time period, dishwasher  2  enters a washing step at which point detergent dispenser  23  is opened, releasing detergent into washing chamber  14  to mix with the water to form a washing fluid. In some instances, the water is heated by heating element  44  prior to the introduction of detergent. In any event, the washing fluid enters pump assembly  30  and is sprayed about washing chamber  14  onto the kitchenware. Often times, periodic partial drain steps are initiated to remove soil accumulating in the washing fluid. That is, depending upon a level of soil in the washing fluid, as sensed by, for example, a turbidity sensor (not shown), some portion of the washing fluid is directed through drain hose  85  and onward to a household drain and additional fresh water is introduced into washing chamber  14 .  
         [0018]     At the completion of the washing step, all of the washing fluid is drained from washing chamber  14  and a rinse step is initiated during which water which forms a fresh washing or rinse fluid is released into washing chamber  14 . Once a sufficient amount of rinse fluid is in washing chamber  14 , pump assembly  30  is activated and the rinse fluid is sprayed through, for example, wash arm  47 , onto the kitchenware. As the rinse fluid circulates throughout the system, heating element  44  is activated to raise the temperature of the rinse fluid. In accordance with the invention, at a predetermined point in the cycle, controller  100  checks to make sure the water temperature exceeds a predetermined threshold temperature, e.g., approximately 125° F. (51.7° C.) as determined by sensor  104 . If not, rinse aid is not dispensed. That is, controller  100  will only release rinse aid when the temperature of the rinse fluid is sufficiently above the cloud point of the rinse aid. More specifically, if, for whatever reason, the temperature of the rinse fluid does not reach the predetermined temperature, controller  100  will not release rinse aid, even though dispenser  24  is full. In this manner, controller  100  ensures that rinse aid dispenser  24  is not activated to release a rinse aid if the temperature of the washing fluid is below the predetermined temperature. Accordingly, upon releasing the rinse aid into the washing fluid, controller  100  ensures that the rinse aid will not foam which could create excessive noise or create cavitations that could be detrimental to pump assembly  30 .  
         [0019]     At this point, it should be readily understood that the present invention ensures that rinse aid is only dispensed when the temperature of the washing fluid is of a sufficient level such that the rinse aid properly mixes with the washing fluid to ensure adequate dispersion within the wash system and eliminate any negative effects that could be associated with foaming of the rinse aid upon mixing with a washing fluid having too low of a temperature. In this manner, the present invention aids in having dishwasher  2  operate quietly and, ultimately, prolongs an overall service life of pump assembly  30 .  
         [0020]     Although described with reference to a preferred embodiment of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, while shown in connection with a conventional dishwasher, the present invention could be readily incorporated into other dishwashers such as, for example, drawer-type dishwashers. Also, the particular type and style of the rinse aid dispenser employed in connection with the present invention can readily vary. In general, the invention is only intended to be limited by the scope of the following claims.