Abstract:
A method and apparatus for providing multiple spray zones, including a localized spray zone for an upper rack and a silverware spray zone for a silverware basket, within the wash chamber of a dishwasher.

Description:
BACKGROUND OF THE INVENTION 
     Automatic dishwashers are commonly found in household environments. A typical automatic dishwasher comprises a cabinet that defines a wash chamber, which is accessible through a moveable door. An upper and a lower rack for holding utensils to be cleaned are provided within the wash chamber. A silverware basket for holding utensils, silverware, etc. is also usually provided and normally removably mounts to the door or within the lower rack. The silverware basket is configured to hold elongated utensils such as knives, spoons, forks, spatulas in a vertical orientation as well as smaller objects that might fall through racks. 
     Liquid is sprayed into the upper and lower racks and the silverware basket to clean any utensils they contain. Rotating spray arms arranged below each rack and spraying upwardly through the bottom of the corresponding rack delivers the liquid to the utensils. The liquid spray pattern is generally in the form of a circle when viewed in planform. The velocity of the liquid exiting the spray arm tends to drop off from the center of the spray arm to the ends of the spray arm. 
     The silverware basket tends to receive less liquid from the spray arms and tends to receive the lower velocity liquid because the silverware basket is located at the periphery of the spray pattern. The volume and velocity of the sprayed liquid reaching the silverware basket are further reduced in that the liquid must pass through the structure of the lower rack as well as the structure of the silverware basket. All of which leads to reduced cleaning performance for utensils in the basket relative to utensils in the lower rack. 
     SUMMARY OF THE INVENTION 
     The invention relates to an automatic dishwasher comprising a wash chamber, an upper rack having a bottom located within the wash chamber, a silverware basket located in the wash chamber beneath the upper rack, an upper spray arm rotatably mounted to the bottom of the upper rack and providing a liquid spray upwardly through the bottom of the upper rack to define a generalized spray zone for the entire upper rack, and an auxiliary sprayer carried by the upper rack and having a localized spray zone directed upwardly to a discrete portion of the upper rack and a silverware spray zone directed downwardly onto the silverware basket. 
     The invention further relates to a method for delivering liquid to a dishwasher by emitting a generalized spray of liquid upwardly through a bottom of a rack, simultaneously emitting a focused spray of liquid upwardly toward a discrete portion of the upper rack, and emitting a spray of liquid toward a silverware basket located beneath the rack. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective view of a first embodiment of an automatic dishwasher, with an auxiliary sprayer providing one or more dedicated spray zones in accordance with the invention. 
         FIG. 2  is a schematic, side-sectional view of the dishwasher of  FIG. 1 . 
         FIG. 3  is a top perspective view of the auxiliary sprayer of  FIG. 1 . 
         FIG. 4A  is a schematic, side-sectional of the dishwasher of  FIG. 1 , illustrating several spray zones in the wash chamber. 
         FIG. 4B  is a schematic, sectional view through an upper rack of the dishwasher, illustrating the spray zones of the upper rack from  FIG. 4A . 
         FIG. 4C  is a schematic, sectional view through a lower rack and silverware basket of the dishwasher, illustrating the spray zones of the lower rack and silverware basket from  FIG. 4A . 
         FIG. 5  is a schematic, side-sectional view of a second embodiment of an automatic dishwasher, illustrating a silverware basket on the door. 
         FIG. 6  is a schematic, front view of a third embodiment of an automatic dishwasher, illustrating a tiered upper rack. 
         FIG. 7  is a schematic illustration of a fourth embodiment of the invention, illustrating a selective operation for the auxiliary sprayer  50 . 
         FIG. 8  is a schematic illustration of a fifth embodiment of the invention, illustrating an alternate liquid supply arrangement for the auxiliary sprayer. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of an automatic dishwasher  10  in accordance with a first embodiment of the invention. As illustrated, the dishwasher  10  includes a housing  12  for enclosing a wash tub  14 . The dishwasher  10  shares many features of a conventional automatic dishwasher, which will not be described in detail herein except as necessary for a complete understanding of the invention. The wash tub  14  has spaced top and bottom walls  16  and  18 , spaced side walls  20 , and a rear wall  22 . The walls  16 ,  18 ,  20 , and  22  join along their respective edges to define a wash chamber  24  with an access opening in the form of an open face  26 . A door  28  is hingedly mounted to the housing  12  and can move between an opened position, as illustrated in  FIG. 1 , to provide access to the wash chamber  24  and a closed position (shown in  FIG. 2 ) to close the wash chamber  24  by covering the open face  26  of the wash chamber  24 . Typically, the door  28  is in the opened position when utensils are loaded or unloaded into the dishwasher  10  and in the closed position while the washing cycle is running or while the dishwasher  10  is not in use. 
     Utensil holders (shown in phantom in  FIG. 1  for clarity of the surrounding structure) in the form of upper and lower racks  30 ,  32  are located within the wash chamber  24  and receive utensils for washing. The racks  30 ,  32  are typically mounted for slidable movement in and out of the wash chamber  24  for ease of loading and unloading. Another utensil holder in the form of a silverware basket  34  is located in the wash chamber  24 . The silverware basket  34  can be mounted to the lower rack  32 , and may be removably mounted. The silverware basket  34  can be positioned along a peripheral side of the lower rack  32 . As illustrated, the silverware basket  34  is positioned along a peripheral side of the lower rack  32  that is parallel to the one of the side walls  20  of the wash tub  14 . Optionally, the silverware basket  34  could be positioned along a peripheral side of the lower rack  32  that is parallel to the rear wall  22  or the door  28  when in the closed position. In yet another option, the silverware basket  34  could be positioned in the upper rack  30 . In still another option, the silverware basket  34  could comprise a separate shallow rack positioned in the wash chamber  24 . 
     Utensil holders  30 ,  32 ,  34  all hold various utensils for washing within the wash chamber. As used in this description, the term utensil is generic to dishes and the like that are washed in the dishwasher  10  and expressly includes, dishes, plates, bowls, silverware, glassware, stemware, pots, pans, and the like. 
       FIG. 2  is a schematic, side-sectional view of the dishwasher of  FIG. 1 . The dishwasher  10  further includes a liquid circulation system  36  for introducing and circulating liquid and wash aids, such as detergents, rinse aids, and the like, throughout the wash chamber  24 . The liquid circulation system  36  comprises a drain pump  37  and a recirculation pump  38  located in a lower portion or sump of the wash tub  14  and which pumps liquid to sprayers  40 ,  42 ,  44  and a sump heater  46  which acts to heat the washing fluid and is located in the lower portion of the dishwasher  10 . The drain pump  37  pumps liquid to a household drain line (not shown). The recirculation pump  38  pumps liquid to sprayers  40 ,  42 ,  44 . As illustrated, liquid is supplied to the sprayers  40  and  42  through a supply tube  48  that extends generally rearwardly from the recirculation pump  38  and upwardly along the rear wall  22  of the tub  14 . While the supply tube  48  ultimately supplies liquid to the sprayers  40 ,  42 , it may fluidly communicate with one or more manifold tubes that directly transport liquid to the sprayers  40 ,  42 . 
     Sprayer  40  is located above the upper rack  30  and is illustrated as a fixed spray nozzle that sprays liquid downwardly within the wash chamber  24 . Sprayers  42 ,  44  are located, respectively, beneath upper rack  30  and lower rack  32  and are illustrated as rotating spray arms. The upper spray arm  42  can be rotatably mounted to the bottom of the upper rack  30  and can provide a liquid spray upwardly through the bottom of the upper rack  30 . The lower spray arm  44  can be rotatably mounted to the pump  38  beneath the lower rack  32  and can provide a liquid spray upwardly through the bottom of the lower rack  32 . The upper spray arm  42  can optionally also provide a liquid spray downwardly onto the lower rack  32 , but for purposes of simplification, this will not be illustrated herein. 
     In addition to the sprayers  40 ,  42 ,  44 , all of which provide generalized sprays of liquid to the wash chamber  24 , the dishwasher  10  includes an auxiliary sprayer  50  for providing one or more focused sprays of liquid to one or more discrete locations within the wash chamber  24 . 
     Referring to  FIG. 3 , the auxiliary sprayer  50  may comprise a fixed spray head  52  having one or more orifices  54 ,  56  for dispensing a stream of liquid forming a spray. The orifices  54 ,  56  can be configured to dispense one or more streams of wash liquid in different directions. As illustrated, the spray head has one upper orifice  54  for dispensing a stream of wash liquid in an upward direction and four lower orifices  56  for dispensing streams of wash liquid in a downward direction. The spray head  52  is mounted to a manifold hub  58  which is hollow and in fluid communication with the supply tube  48  via a manifold tube  60 . The manifold tube  60  thus supplies liquid to both the upper spray arm  42  and the auxiliary sprayer  50 . In the illustrated embodiment, liquid is simultaneously supplied to the upper spray arm  42  and the auxiliary sprayer  50  during operation of the dishwasher  10  so that liquid is sprayed concurrently by the upper spray arm  42  and the auxiliary sprayer  50 . The rotation of the upper spray arm  42  may interfere with the spray of liquid from the auxiliary sprayer  50 , especially for the downwardly directed stream of wash liquid from the lower orifices  56 , thus potentially creating a pulsing or intermittent stream from the auxiliary sprayer  50 . 
     The auxiliary sprayer  50  may be carried by the upper rack  30 , above or below a bottom wall of the upper rack  30 , or adjacent a peripheral side of the upper rack  30 . As illustrated, the auxiliary sprayer  50  is coupled to the upper spray arm  42  and is positioned below the bottom wall of the upper rack  30 . One or more brackets  62  or other suitable fixation means mounts the hub  58  to the upper rack  30  ( FIG. 2 ), thus mounting both the upper spray arm  42  and the auxiliary sprayer  50  to the upper rack  30 . Alternately, the auxiliary sprayer  50  may be mounted separately from the upper rack  30 . 
     Referring to  FIGS. 4A-4C , several spray zones in the wash chamber  24  are schematically illustrated. It is understood that the spray zones are not necessarily drawn to scale, and may be disproportionate to each other and to other features of the dishwasher  10 . The upper spray arm  42  can provide a liquid spray upwardly through the bottom of the upper rack  30  to define a first generalized spray zone  64  for the entire upper rack  30 . The lower spray arm  44  can provide a liquid spray upwardly through the bottom of the lower rack  32  to define a second generalized spray zone  66  for the entire lower rack  32 . The fixed spray nozzle  40  can provide a downwardly-directed liquid spray to define a third generalized spray zone  68  for the wash chamber  24 , particularly the upper rack  30 . 
     The auxiliary sprayer  50  can provide an upwardly-directed liquid spray through the bottom of the upper rack  30  to define a localized spray zone  70  for a discrete portion of the upper rack  30 . The upwardly-directed liquid spray is provided by the upper orifice  54  ( FIG. 3 ). The localized spray zone  70  intersects with the first generalized spray zone  64  for a combined washing action in a discrete area of the upper rack  30 , as indicated by the intersecting zones  64 ,  70  in  FIG. 4B . The discrete area thus receives a more intense or concentrated wash than other areas of the upper rack  30 . The intensified or concentrated wash may be attributable to one or both of the overlapping spray zones and the localized spray zone  70  can further have a greater pressure at the same elevation within the wash chamber  24  than the generalized wash zone  64 . 
     The auxiliary sprayer  50  can further provide a downwardly-directed liquid spray toward the silverware basket  34  to define a silverware spray zone  72  for the silverware basket  34 . The downwardly-directed liquid spray is provided by the lower orifices  56  ( FIG. 3 ). The silverware spray zone  72  intersects with the second generalized spray zone  66  for a combined washing action in a discrete area encompassing the silverware basket  34 , as indicated by the intersecting zones  66 ,  72  in  FIG. 4C . The silverware basket  34  thus receives a more intense or concentrated wash than other areas of the lower rack  32 . 
     The localized spray zone  70  can be designed to allow tall items such as glassware to receive the traditional wash provided by the upper spray arm  42  and the fixed spray nozzle  40 , as well as an additional focused wash action from the auxiliary sprayer  50 . Likewise, the silverware spray zone  72  can be designed to allow silverware to receive the traditional wash provided by the lower spray arm  44 , as well as an additional focused wash action from the auxiliary sprayer  50 . Thus, a dishwasher  10  having such a localized spray zone  70  and a silverware zone  72  may not only provide better washing performance for tall items and silverware, but may provide overall improved wash performance. 
       FIG. 5  is a schematic, side-sectional view of a second embodiment of an automatic dishwasher  10 , in which like elements are identified using the same reference numerals. For the second embodiment of the dishwasher  10 , the silverware basket  32  is located on the door  28 . The silverware basket  32  can be removably mounted to the door  28 . The localized spray zone  70  can be substantially identical to that of the first embodiment; however, the silverware spray zone  72  can be modified to account for the relocated silverware basket  32 . Accordingly, the downwardly-directed liquid spray provided by the lower orifices  56  ( FIG. 3 ) may be angled towards the door  28  to reach the silverware basket  32 . 
       FIG. 6  is a schematic, front view of a third embodiment of an automatic dishwasher  10 , in which like elements are identified using the same reference numerals. For the third embodiment of the dishwasher  10 , the upper rack  30  is tiered to accommodate utensils of varying heights. The upper rack  30  includes a generally angled lower wall  74  with a guard wire  75  depending therefrom. Furthermore, a modified auxiliary sprayer  50  is illustrated. Instead of being mounted to the hub  58 , the auxiliary sprayer  50  is supported on a second manifold tube  76  that extends outwardly from the hub  58 . The auxiliary sprayer  50  may be further supported by a bracket  62  or other suitable fixation means attached to the guard wire  75 , although it could alternately be attached to the lower wall  74 . The manifold tube  60  still supplies both the upper spray arm  42  and the auxiliary sprayer  50  with liquid via the manifold hub  58 , but the liquid must further travel through the second manifold tube  76  to reach the auxiliary sprayer  50 . 
       FIG. 7  is a schematic illustration of a fourth embodiment of the invention, illustrating a selective operation for the auxiliary sprayer  50 . For the fourth embodiment, a valve  78  is positioned between the upper spray arm  42  and the auxiliary sprayer  50  so the liquid is selectively supplied to the auxiliary sprayer  50  during operation of the dishwasher  10 . The valve  78  controls whether liquid is being sprayed by the auxiliary sprayer  50 . Thus, when the valve is closed, liquid will not be sprayed by the auxiliary sprayer  50 . When the valve  78  is open, liquid can be sprayed concurrently by the upper spray arm  42  and the auxiliary sprayer  50 . The valve  78  can alternately be configured to divert only a portion of liquid from the upper spray arm  42  to the auxiliary sprayer  50 . 
     The opening and closing of the valve  78  can be automatically controlled in accordance with an operational or wash cycle of the dishwasher  10 , or can be controlled by the user who may elect when the localized spray zone  70  and the silverware spray zone  72  are needed for additional focused wash action to discrete areas of the dishwasher  10 . While not illustrated herein, an additional valve can be utilized for the auxiliary sprayer  50  to control liquid flow to one or both of the orifices  54 ,  56 , so that one or both of the localized spray zone  70  and the silverware spray zone  72  are operating. 
       FIG. 8  is a schematic illustration of a fifth embodiment of the invention, illustrating an alternate liquid supply arrangement for the auxiliary sprayer  50 . For the fifth embodiment, a separate manifold tube  80  is in fluid communication with the supply tube  48  to supply liquid to the auxiliary sprayer  50 , while the upper spray arm  42  is supplied with liquid through the manifold  60 , like the first embodiment. Liquid can be simultaneously supplied to both manifold tubes  60 ,  80  during operation of the dishwasher  10  so that liquid is sprayed concurrently by the upper spray arm  42  and the auxiliary sprayer  50 . Alternately, an optional valve  82  can control whether liquid is delivered to the manifold tube  60  supplying the upper spray arm  42  or the manifold tube  80  supplying the auxiliary sprayer  50 . 
     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. For example, the auxiliary sprayer  50  of the invention can be applied to any rack within a dishwasher, and it is not limited to the upper rack  30 . For example, in a dishwasher having three racks, the auxiliary sprayer  50  could be mounted to the middle rack or the topmost rack. 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.