Abstract:
A fluid dispensing system for a dishwasher is disclosed, wherein the dishwasher comprises a housing, a wash chamber enclosed by the housing, and a door for accessing the wash chamber. The dispensing system, in particular, comprises a fluid reservoir for containing a wash aid (such as detergent or a rinse aid) which may be used to treat dishes in the dishwasher wash chamber during a dish cleaning cycle. The system further comprises a pump for dispensing a predetermined quantity of the wash aid from the reservoir into the dishwasher wash chamber and into the reservoir from a supply reservoir one or more times during the dish cleaning cycle. A dual purpose check valve is provided for controlling fluid flow in two opposing directions between the pump and the fluid reservoir. The dual purpose check valve comprises a duckbill valve portion for controlling fluid flow in a first direction, and an umbrella valve portion for controlling fluid flow in an opposing second direction.

Description:
This application claims the benefit under 35 U.S.C. 119(e) of the filing date of Provisional U.S. Application Ser. No. 60/857,983, entitled Design and Method for a Dripless Liquid Wash Aid Pumping Mechanism, filed on Nov. 8, 2006. This provisional application is expressly incorporated herein by reference in its entirety. This application is also related to co-pending U.S. application Ser. No. 11/437,427, entitled Bulk Dispensing of Chemicals Into a Residential Dishwasher, filed on May 19, 2006 and commonly assigned herewith, which application is also herein expressly incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to chemical dispensing systems, and more particularly, to systems for bulk dispensing of chemicals, such as detergents, into a residential dishwasher. 
     BACKGROUND OF THE INVENTION 
     Typically, residential dishwashing machines include built-in single-dose detergent dispensers. A single-dose dispenser must be re-filled every time the dishwashing machine is to be used, which requires an extra step. Additionally, manual filling of the dispenser cup often leads to accidental overfilling or underfilling. 
     What is needed, therefore, is a bulk detergent dispenser that does not need to be refilled every time that it is used, and can automatically dispense the correct amount of detergent, at the right time or times during the machine&#39;s operating cycle. 
     SUMMARY OF THE INVENTION 
     The inventive dispensing system comprises a detergent reservoir that can hold liquid gel dish detergent in bulk quantities, preferably comprising the contents of at least one bottle of detergent as sold at retail, which is disposed inside the dishwasher. The reservoir is filled with detergent from the inside of the door, to facilitate clean-up if any product is accidentally spilled. As a result, the dishwasher is made easier and more convenient to use, by reducing the repetitive step of loading detergent and allowing “peace of mind” delegation of the dishwashing task. 
     Metered dosage control is an added benefit of the present invention. 
     More particularly, in one aspect of the invention, there is provided a fluid dispensing system for a dishwasher, particularly for residential use, wherein the dishwasher comprises a housing, a wash chamber enclosed by the housing, and a door for accessing the wash chamber. The dispensing system comprises a fluid reservoir adapted to be disposed in the door for containing fluid (preferably liquid dishwashing detergent) which may be used to treat dishes in the wash chamber during a dish cleaning cycle. The system further comprises a pump which is adapted to be disposed in the door, in proximity to the reservoir, for dispensing a predetermined quantity of the fluid from the reservoir into the dishwasher wash chamber one or more times during the dish cleaning cycle. The pump preferably comprises a reciprocating plunger pump, and is solenoid-actuated. 
     The reservoir has a fluid capacity sufficient for a plurality of dish cleaning cycles without the need for replenishment. In preferred embodiments, the reservoir fluid capacity is approximately equal to the capacity of a typically sized single container of fluid (typically dishwashing detergent) available at retail, so that the consumer may empty the entire contents of the container (bottle) into the reservoir at one time, and then dispose of the container. 
     In addition to dishwashing detergent, the fluid contained in the reservoir may comprise a dishwasher rinse aid. In one embodiment of the invention, two reservoirs are provided, one of which contains dishwashing detergent, and the other of which contains dishwasher rinse aid. 
     The above described predetermined quantity (metered dosage) of fluid is preferably adjustable responsive to either controller or user input. Controller input might include, for example, feedback from dish soil sensors which cause the controller to adjust detergent levels to address the sensed soil concentrations. User input might include, for example, depressing a particular dish cycle selector button on the dishwasher, such as “normal cycle” or “pots and pans cycle”. 
     In particular, the dishwasher door described above comprises an interior panel having a recess sized to accommodate the reservoir. The reservoir is thus adapted to be disposed in the recess, in flush-mounted fashion. The reservoir is preferably adapted to be snap-fit into the recess and to be retained therein because of an interference fit. It is adapted to be removed from the recess and re-installed in the recess without using tools, for easy clean-up or re-filling, if desired. It should be noted, however, that the reservoir may also be readily re-filled while installed in the door panel. The reservoir includes an inlet, and may be filled and re-filled with fluid through the inlet. In one alternative embodiment, the reservoir is pre-filled with fluid, and disposable once empty, and is not re-Tillable with additional fluid. The reservoir is preferably translucent, so that a level of fluid remaining in the reservoir may be readily determined by a user. 
     The pump may also be removed and installed without using any tools. 
     In another aspect of the invention, there is provided a dishwasher for residential use, which comprises a housing and a wash chamber enclosed by the housing. A door is provided in the housing for accessing the wash chamber. A fluid reservoir is disposed in the door for containing fluid (preferably liquid dishwashing detergent) which may be used to treat dishes in the wash chamber during a dish cleaning cycle. A pump is also disposed in the door, in proximity to the reservoir, for dispensing a predetermined quantity of the fluid from the reservoir into the wash chamber one or more times during the dish cleaning cycle. The pump preferably comprises a reciprocating plunger pump, and is solenoid-actuated. 
     In yet another aspect of the invention, there is provided a method for washing dishes in a residential dishwasher during a dish cleaning cycle, which comprises a step of actuating the dish cleaning cycle, and a further step of actuating a dispenser pump in a door of the dishwasher, for dispensing a metered dosage of dish detergent from a reservoir in said door into a wash chamber in the dishwasher. A further step comprises actuating the dispenser pump a second time during the dish cleaning cycle to dispense a further metered dosage of dish detergent from the reservoir into the wash chamber. In one example of such an operational mode, the first step may occur during a pre-wash cycle, and the second step may occur during a main wash cycle. The dispenser pump actuation step is preferably performed using a solenoid actuator. When the dispenser pump is actuated, a plunger in the pump reciprocates in one direction to draw a metered dose of detergent into a pumping chamber, after which the plunger reciprocates in an opposing direction to dispense the detergent in the pumping chamber into the wash chamber. 
     In a further aspect of this method, an additional step comprises removing the reservoir from the door, cleaning the reservoir, and replacing the reservoir back into the door, without the use of any tools. 
     In still another aspect of the invention, there is provided a fluid dispensing system for a dishwasher, wherein the dishwasher comprises a housing, a wash chamber enclosed by the housing, and a door for accessing the wash chamber. The dispensing system, in particular, comprises a fluid reservoir for containing a wash aid which may be used to treat dishes in the dishwasher wash chamber during a dish cleaning cycle. It further comprises a pump for dispensing a predetermined quantity of the wash aid from the reservoir into the dishwasher wash chamber and into the reservoir from a supply reservoir one or more times during the dish cleaning cycle. A dual purpose check valve is provided for controlling fluid flow in two opposing directions between the pump and the fluid reservoir. 
     Preferably, the dual purpose check valve comprises a duckbill valve portion for controlling fluid flow in a first direction, and an umbrella valve portion for controlling fluid flow in an opposing second direction. 
     The invention, together with additional features and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying illustrative drawings. In these accompanying drawings, like reference numerals designate like parts throughout the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a residential dishwasher which is equipped with a bulk detergent dispenser feature in accordance with the present invention; 
         FIG. 2  is a perspective view of the bulk detergent dispenser of  FIG. 1 , shown in isolation; 
         FIG. 3  is a perspective view of the interior of the dishwasher door, showing the bulk detergent dispenser of  FIG. 2  installed therein; 
         FIG. 4  is a perspective view illustrating the fluid connection between the dispenser reservoir and liquid pump shown in  FIG. 2 ; 
         FIG. 5  is a perspective view illustrating the solenoid installation; 
         FIG. 5A  is an enlarged view of a portion of  FIG. 5 , showing the solenoid installation more clearly; 
         FIG. 6A  is a perspective view of one embodiment of the liquid detergent pump of the present invention; 
         FIG. 6B  is a perspective view of the liquid detergent pump of  FIG. 6A , shown in cross-section in order to illustrate the internal mechanisms of the pump; 
         FIG. 7A  is a perspective view of an umbrella check valve which may be employed in the present invention; 
         FIG. 7B  is a perspective view of check valve seats which may be employed in the present invention; 
         FIG. 7C  is a schematic view illustrating the function of the check valves employed in the present invention; 
         FIG. 8  is a perspective view illustrating the detergent pump discharge structure; 
         FIG. 9  is a perspective view of the dish detergent dispenser of  FIGS. 1-8 , illustrated in an exploded view the construction of the detergent pump; 
         FIG. 10  is a perspective view similar to  FIG. 2 , illustrating a modified embodiment of the dispenser of the present invention which comprises both a detergent and a rinse aid dispenser; 
         FIG. 11  is a perspective view, from the rear, showing the embodiment of  FIG. 10 ; 
         FIG. 12  is a plan view of a modified embodiment of the present invention, showing the installation of a detergent reservoir in the door of a dishwasher; 
         FIG. 13  is a schematic view of a further modified embodiment of the present invention; 
         FIG. 14  is a front view of a another embodiment of a wash aid pumping system for a residential dishwasher, constructed in accordance with the principles of the present invention; 
         FIG. 15  is a side view of the system illustrated in  FIG. 14 ; and 
         FIG. 16  is a cross-sectional view taken along lines A-A of  FIG. 15 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, there is shown a residential dishwasher  10  having a hinged door  12  and a main housing  14 . The dishwasher  10  provides a method for storage and injection of chemicals into the washing chamber  16  thereof. The device is designed to store one complete container of the most common-sized chemical found in the market. The device can inject a plurality of chemicals (detergents and rinse aids are the most common), which are supplied in a liquid state. 
     A detergent reservoir  18  is flush-mounted inside the door  12  of the dishwasher  10 , and is filled via a fill spout  20 . A wide, easy-fill quarter-turn lid  22  is recessed within the fill spout  20  to prevent over-filling of the reservoir. A reservoir  18  is supplied with the dishwasher and is reusable for the lifespan of the dishwasher, in one embodiment, but in an alternative embodiment, a ready-to-use disposable cartridge, formed by inexpensive blow-molding techniques to fit the provided recess in the door, is pre-filled with detergent and sold to the consumer for installation directly into the door reservoir recess. In this alternative embodiment, a simple cap, rather than the illustrated wide lid, is provided, since there is no necessity for the consumer to fill the reservoir, and thus no chance of spillage. The reservoir further includes a hydrophobic vent (not shown) to ensure that the detergent reservoir  18  does not collapse when dispensing product. The vent is preferably a labyrinth-seal type vent to allow air movement in both directions, but excludes water from entering the reservoir or detergent from weeping out. Air enters the reservoir when the detergent is dispensed, through the vent, in order to prevent the reservoir from collapsing. As the temperature rises during the operating cycle of the appliance, expanding air inside the reservoir exits through the vent. 
     Advantageously, the reservoir  18  may be transparent or translucent to permit an operator to readily determine the detergent level in the reservoir. Alternatively, other known gauging systems may be employed. 
     The inventive dish detergent dispenser comprises four components. In addition to the reservoir  18 , the dispenser comprises a dispenser pump  24  ( FIG. 2 ), a solenoid actuator  26 , and a circuit board/controller (not shown). All of the components  18 ,  24 ,  26  are mounted in the door  12 . The circuit board/controller may be mounted anywhere on the dishwasher, including the door, as long as the selected location is sealed from contact with liquids in order to protect the electronics. The controller electronically controls the dispensing function for precision and differentiation. 
     As noted above, and referring particularly to  FIGS. 2 and 3 , both the detergent reservoir  18  and the dispenser pump  24  are semi-flush mounted inside recesses within the door  12 , as illustrated in  FIG. 3 . Both components snap in easily to the inside face of the door, with an interference fit, as shown. The reservoir&#39;s interference fit with respect to the recess is a rather loose one, owing to the relatively thin-walled construction of the reservoir. On the other hand, the interference fit of the pump in its respective recess is rather tight, owing to the relatively thick-walled construction of the pump body. 
     The solenoid actuator  26  is mounted behind the door panel, which may be fabricated of stainless steel or other suitable materials, for safety and protection. The reservoir  18  is preferably designed to hold the contents of one “grocery store” bottle. Since the fill location  22  of the reservoir  18  is inside the dishwasher, spill clean up is easy. The semi-flush mounting design makes the reservoir of a sufficiently low profile so that it does not interfere with the lower rack as it slides in and out, nor does it substantially reduce usable tub volume (volume of the washing chamber  16 ). 
     As shown in  FIG. 4 , engaging seals  28 ,  30  on the reservoir  18  and the pump  24 , respectively, allow the reservoir and pump to be easily snapped together with a tight seal. The same interface design is provided for the alternative embodiment (not shown) discussed above, which employs a pre-filled recess-fitting detergent cartridge. 
       FIGS. 5 and 5A  illustrate, in tiled figures, the rear side of the inner door panel  12 , so that the solenoid can be seen behind the panel, on the “dry” side of the panel. As can be seen, only one access hole  32  is provided in the panel  12 , for accommodating the connector  34  between the solenoid  26  and the pump  24 . Preferably, a soft elastomeric accordion seal (not shown) is employed to seal this hole  32 , which provides a low stress seal even with lots of axial movement. Such a static seal ensures lifetime leak-free performance. 
     As shown in  FIGS. 6A and 6B , the preferred detergent pump  24  has few parts. The one moving part is actually part of the solenoid actuator  26 . As noted previously, the pump  24  is wetted in the dishwasher, while the solenoid  26  is isolated on the dry side of the panel. The pump is a simple plunger pump, comprising a detergent batch chamber  36  having an inlet port  38 , a pumping chamber  40 , defined by a reciprocating plunger  42 , a pumping chamber inlet port  44 , and a pumping chamber outlet port  46 . The plunger  42  is driven by the solenoid actuator  26  and preferably includes wiper seals for sealing the pumping chamber  40 . Any weeping past the wiper seals goes into the wash chamber  16 , where the detergent is destined to go anyway. The plunger is spring-loaded, and is normally extended all the way into the pumping chamber. Energizing the solenoid  26  causes the plunger to retract, drawing liquid from the batch chamber  36  to the pumping chamber  40  through the pumping chamber inlet port  44 . De-energizing the solenoid actuator  26  causes the spring to relax, extending the plunger  42  and thus dispensing detergent from the pumping chamber  40  through the pumping chamber outlet port  46 . Advantageously, large passages and short flow paths are employed to permit free movement of thick gel detergent. 
     Now with reference particularly to  FIGS. 7A ,  7 B, and  7 C, an umbrella check valve  48  is preferably employed in each of the pumping chamber inlet and outlet ports  44 ,  46 , respectively. Valve seats  50  for each of the inlet and outlet ports are shown in  FIG. 7B . Umbrella check valves are preferred because they comprise soft elastomers that move easily and have low stress. As shown in  FIG. 7A , an extended piece  52  is employed to pull the valve through the mounting hole. This piece  52  is designed to break off after pull-through, during assembly. The valve seats  50  utilize large passages in order to maintain low liquid resistance. A plug  54  ( FIG. 7C ) is disposed in the discharge passage in order to finish the pump. 
       FIGS. 8 and 9  illustrate additional details of the inventive dispensing system. 
     In operation, when the dishwasher door  12  is opened, the pump batch chamber  36  is filled. When the door is closed, excess detergent runs out of the batch chamber, leaving a full batch of predetermined volume of detergent behind. The “full batch” of detergent typically includes a smaller volume for a pre-wash cycle and a larger volume for a main wash cycle. In one particular embodiment, for example, a full batch is approximately 60 ml, including 20 ml for a pre-wash cycle and 40 ml for a main wash cycle, but these values may vary, depending upon application and specifications of the particular dishwasher in which the dispenser is disposed. Also, when the door is closed, the detergent level in the main reservoir drops below the batch chamber fill port to prevent re-filling. 
     This main reservoir/batch chamber design effectively isolates the main reservoir from water contamination. Water would need to flow against two check valves, then up and over the spillway to gain access to the main chamber. 
     Each stroke of the solenoid pushes a small amount of detergent into the dishwasher wash chamber, through a discharge passage  56 . A full pre-wash dose typically requires a few strokes. A full dose of main wash requires more strokes. For example, in one particular embodiment, each stroke of the solenoid dispenses approximately 4 ml of detergent into the wash chamber. In this embodiment, five strokes of the solenoid supplies sufficient detergent for a pre-wash cycle and ten strokes of the solenoid supplies sufficient detergent for a main wash cycle. Of course, these particular values are exemplary only, and subject to dishwasher specifications, soil load, and the like. 
     The batch chamber  36  need not be emptied on every wash cycle. It is all right to utilize less detergent for a particular load and to leave the chamber partially filled. It should be noted that the detergent pump discharge passage  56  is preferably wide and short, for two primary reasons. One reason is to ensure that there is absolutely minimal liquid resistance for the pump to overcome. The second reason is so that spray water from the washing chamber  16  splashes the passage  56  clean, but cannot get past the pump outlet passage umbrella valve  48 . 
     In  FIGS. 10 and 11 , there is shown a modified embodiment of the detergent reservoir  18 , which includes a second reservoir  58 , for dispensing a rinse aid or the like. A second dispenser pump  60  and solenoid actuator  62  may be utilized to dispense the rinse aid. As presently embodied, the rinse aid dispensing system essentially duplicates the detergent dispensing system described above. 
     Three versions of the inventive detergent dispensing system are currently contemplated. A first, basic version dispenses a fixed amount (40 ml in one exemplary embodiment) of detergent automatically when called upon by the dishwasher. This version may or may not allow prewash dosing. A second, more sophisticated version dispenses a variable amount of detergent, the adjustment being enabled using an electrical dial on the control panel of the dishwasher, often located on the door. The volume ranges from “minimum” to “normal”, to “heavy load”. A third, even more sophisticated version dispenses a variable amount of detergent driven from a soil load sensing technology, which is a sensor system having a capability of detecting the level of soil present on the dishes being washed. In this version, the consumer also has the option of overriding with a manual volume dial. 
     Now with reference to  FIG. 12 , a modified embodiment of the reservoir and pump of the present invention is illustrated. In this embodiment, a detergent reservoir  18 ′ is flush-mounted in an inside panel of a dishwasher door  12 ′. The reservoir  18 ′ has a lid  22 ′ for closing a fill spout  20 ′. The lid  22 ′ is of the “flip-top” type, and may be flipped between the illustrated closed position, and an open position for filling the reservoir  18 ′. A fingertip recess  64  is provided for enabling a user&#39;s fingertip to engage and open the lid  22 ′. A dispenser pump  24 ′ is provided directly beneath the reservoir  18 ′, as shown, having a fluid discharge passage  56 ′. The pump  24 ′ is constructed in a similar manner to that discussed above with respect to pump  24 . An advantage of this embodiment is to improve flow of fluid from the reservoir into the pump, because of the immediate proximity of the reservoir outlet to the pump inlet. 
     In  FIG. 13  there is shown yet another modified embodiment of the invention, including a reservoir  18 ″ having a lid  22 ″ similar to the lid  22  of the first illustrated embodiment. Again, at the base of the reservoir  18 ″, which is adapted for disposition in a dishwasher door, as in prior embodiments, is a dispenser pump  24 ″. The dispenser pump  24 ″ comprises a solenoid actuator  26 ″ and a discharge passage  56 ″. In this embodiment, as in the  FIG. 12  embodiment, fluid flow from the reservoir into the pump is facilitated by the immediately proximity of the pump inlet beneath the reservoir outlet. 
     Now, with particular reference to  FIGS. 14-16 , yet another embodiment of a pump useful in combination with the foregoing dishwasher fluid dispensing system will be described. The dispenser pump  24  comprises a dripless pump mechanism having a single dual purpose check valve  66  that incorporates both an input and output function. 
     The dual purpose check valve  66 , as shown, operates as a duckbill check valve for the input of the wash aid, such as a detergent or rinse aid, and an umbrella shaped check valve for the output of wash aid to the wash chamber. The arrangement of the duckbill and umbrella function can also be reversed, if desired. 
     The dual purpose check valve  66  is attached to a piston cylinder body  68  that on one end incorporates an aperture  69   a  to receive the duckbill valve component  69   b  of the dual purpose valve  66 . Surrounding the aperture  69   a  that receives the duckbill valve  69   b  are openings  69   c  arranged circumferentially to the hole. The outer edge of these openings are within the diameter of the umbrella portion  69   d  of the dual check valve. Within the piston body  68  is a unibody piston  70  that incorporates two seal rings  72 ,  74 . These seal rings create a minimum interference to the cylinder wall. The seal rings are oriented in opposing directions. The first seal ring  72  faces the dual-purpose check valve  66  on one end of the cylinder body  68 , while the second seal ring  74  faces in the opposite direction. 
     The unibody piston  70  includes a mating surface to the dual purpose check-valve  66  so that when the piston is in a fully dispensed position there is virtually no residual wash aid remaining in the space between the first seal ring  72  and the duck bill feature of the dual purpose check valve  66 . In addition, when the piston is in the fully dispensed position (piston moved to its left-most position), the piston incorporates a feature that captures the duckbill valve portion  69   b  so that the tip of the valve is permanently pinched off when not in use. 
     When the pump mechanism is in the fully dispensed position, there is no liquid drip or seepage. This is due to a combination of the following advantageous features, which are discussed above:
         a. there is minimized space between the first sealing ring  72  and the duckbill portion  69   b  of the dual valve  66 , which prevents leakage out of the pump system by way of the umbrella valve portion  69   d ; and   b. the duckbill valve portion  69   b  is pinched off, which prevents seepage of the liquid into the pump body.       

     Another advantageous feature of this embodiment is a dripless reservoir-to-pump connection. More particularly, an interconnection between a reservoir  18  for the wash aid and the pump  24  is made using a tube  76 . The tube  76 , when connected to the pump body  68 , probes into the inside diameter of the duckbill check valve  69   b  in the pump body, which then creates a conduit between the fluid-filled reservoir  18  and the pump input. 
     In one embodiment, the tube  76  is connected to the duckbill check valve portion  69   b  on the reservoir side of the pump  24 . The tube  76  probes into the inside diameter of the duckbill check valve portion  69   b , which then creates a conduit between the fluid-filled reservoir  18  and the pump input, as discussed above. However, this duckbill check valve portion  69   b  is now connected to the reservoir. 
     In an alternative approach, there is a reservoir cap  78 , wherein one end  80  of the hollow tube  76  extends from the center of the cap  78  into the interior of the reservoir  18 . The end of the tube incorporates a disengageable cap, integral membrane, or TPE valve  82 . During attachment of the reservoir  18  to the pump  24 , the reservoir cap  78  is pushed onto the end of the tube  76 . This tube  76  then penetrates the reservoir cap  78  via an inlet at the surface of the reservoir cap and dislocates or pierces the inner cap components. This connection creates a conduit between the fluid-filled reservoir and the pump body. 
     The reservoir cap  78  is preferably vented, thus venting the reservoir  18  in order to prevent back suction or reservoir collapse. The vented reservoir cap or plug incorporates, preferably, a straw-like component. This straw extends from the cap end of the reservoir to the opposite end thereof at the deepest location of the reservoir. During dispensing of the liquid wash aid, air is pulled into the inner volume of the reservoir, through the straw member, as the liquid exits through the tube  24 . An equal volume of air will always replace the displaced liquid, preventing the reservoir from vacuum collapsing. Alternative venting schemes may be employed, if desired. 
     While this invention has been described with respect to various specific examples and embodiments, it is to be understood that various modifications may be made without departing from the scope thereof. Therefore, the above description should not be construed as limiting the invention, but merely as an exemplification of one preferred embodiment thereof.