Abstract:
A dishwashing apparatus and a methodology are provided for washing dishware using electrolyzed water to provide alkaline and acidic water for wash and rinse cycles. The water used at the beginning of a pre-wash stage is repeatedly used in plural pre-wash cycles and filtered through sediment and oil filtration between pre-wash cycles. Water from a final rinse cycle is saved for use for future pre-wash cycles. The sediment and oil filtration filter are reversely flushed to regenerate the filtration systems.

Description:
FIELD OF THE INVENTION 
       [0001]    The present subject matter relates to dishwashers. More specifically, the present subject matter relates to dishwashers and methods for operating such with reduced water and energy consumption and without requiring the use of detergent. 
       BACKGROUND OF THE INVENTION 
       [0002]    Commonly available dishwashers such as the current GE Profile dishwasher consumes approximately 7.2 gallons of water to clean a heavily soiled ten place setting dish load in normal cycle and consumes approximately 2.17 kWh energy in the process. 
         [0003]    Some prior devices have been developed that recover and store washing liquids including, for example, EP 0 691 099 A3 assigned to Candy S.p.A, thereby addressing concerns relating to water usage. Other dishwashers, for example as described in U.S. Pat. No. 5,947,135, wash and rinse tableware using variously ionized water. U.S. Pat. No. 6,832,617 describes a dishwasher fine filter assembly. 
         [0004]    In view of these known concerns and ongoing efforts, it would be advantageous to provide an ecologically friendly and efficient dishwasher that uses significantly less water and with less energy consumption while not requiring the use of detergents. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
         [0006]    The present subject matter relates to apparatus and methodologies for providing and operating a dishwasher unit (herein after described as an eco-dishwasher) that is designed and operated in such a manner so as to consume significantly less water and electrical energy than previously known devices while at the same time performing an effective cleaning operation without requiring the use of detergents. In an exemplary configuration, an eco-dishwasher constructed in accordance with present technology may use only approximately 3.6 gallons of water and approximately 0.94 kWh of electrical energy with no detergent consumption for an exemplary heavily soiled ten place setting dish load. 
         [0007]    In certain embodiments, the present technology relates to a dishwasher that includes a main cabinet configured to hold items to be washed. An electrolysis system is configured to generate acidic and alkaline water from a water supply. The dishwasher includes an acidic water storage tank, an alkaline water storage tank, a sedimentation filtration system, an oil filtration system, and a controller. The controller is configured to cause the dishwasher to perform a plurality of pre-wash cycles using fresh water from a tap or previously stored final rinse water filtered through the sedimentation filtration system and the oil filtration systems following each pre-wash cycle or fresh tap water, to perform a wash cycle using alkaline water, to perform a rinse cycle using acidic water, to perform a final rinse cycle using water from a water supply, and to store the final rinse water in the alkaline water storage tank upon completion of the rinse cycle for use in subsequent pre-wash cycles or to drain the final rinse water without storing. 
         [0008]    In selected embodiments, the sedimentation filtration system has a first filter having a first mesh size and a second filter having a second mesh size. In particular embodiments, the first mesh size may be from about 100 microns to about 1 mm and the second mesh size may be between about 5 to 100 microns. In particular embodiments, the oil filtration system comprises a filter made of material having hydrophobic and oleophilic surface characteristics that in certain embodiments may correspond to a filter made of kapok. 
         [0009]    In other embodiments, the dishwasher controller may cause a filtration process to be performed by causing water used for the plurality of pre-wash cycles to be reverse flushed through the sedimentation filtration system and the oil filtration system to regenerate the filtration systems. The controller may be further configured to cause the filtration process to be performed between pre-wash cycles, simultaneously with spraying of water into the main cabinet, or continuously as single pre-wash cycles until substantially all contamination is filtered out. 
         [0010]    In certain selected embodiments of the preset subject matter, a heater may be positioned within the main cabinet or the dishwasher sump to heat the wash and final rinse cycle water. In other selected embodiments, a drain is provided to drain stored previous final rinse water if a subsequent pre-wash cycle is not begun within a predetermined period of time. 
         [0011]    The present subject matter also relates to methods for operating a dishwasher to wash items placed in the main cabinet of the dishwasher. The method includes electrolyzing water to generate acidic and alkaline watery, and storing the alkaline water in a first storage tank and storing the acidic water in a second storage tank. A sedimentation filtration system and an oil filtration system are provided. The method includes performing a plurality of pre-wash cycles using previous final rinse water, filtering the water through the sedimentation filtration system and the oil filtration systems, performing a wash cycle using alkaline water, performing a rise cycle using acidic water, performing a final rinse cycle using water from a water supply, and draining the final rinse water into one of a storage tank for use in subsequent pre-wash cycles or from the dishwasher. 
         [0012]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0014]      FIG. 1  is a block diagram of a electrolysis, detergent free washing system in accordance with present technology; 
           [0015]      FIG. 2  is diagrammatic illustration of an electrolysis cell; 
           [0016]      FIG. 3  is diagrammatic illustration of an electrolysis system design; 
           [0017]      FIG. 4  is a graphical representation of exemplary Base and Acid liquid generation results in accordance with present technology; 
           [0018]      FIG. 5  is a block diagram representing pre-wash, filtration, and regeneration processes in accordance with present technology; 
           [0019]      FIG. 6  is a flow chart illustrating steps in an exemplary dishwashing cycle per present technology; and 
           [0020]      FIG. 7  is a schematic representation of relationships among various components of an exemplary dishwashing system per present technology. 
       
    
    
       [0021]    Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features or elements of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0023]    As noted in the Summary section, the present subject matter is directed toward dishwashers configured for operation with reduced water and energy consumption and without requiring the use of detergent. A full-scale eco-dishwasher unit constructed in accordance with present technology is designed to operate using only approximately 3.6 gallons of water, approximately 0.94 kWh of electrical energy, and no detergent consumption. These values are not, however, limitations of the invention. 
         [0024]    With reference now to  FIG. 1 , there is illustrated a block diagram of an electrolysis, detergent free washing system  100  in accordance with present technology. The electrolysis, detergent-free system  100  uses alkaline wash technology wherein hydroxyl ions are generated at the point of use and worked in place of detergents. An electrochemical compartment  102  is designed such that direct water splitting generates hydroxyl ions. More particularly, electrolysis system  102  is configured to split water supplied from, for example, a tap water supply  104 , and to store the split water in an acid storage tank  132  and a base storage tank  134 . In an exemplary system, about two fill volumes of water is converted into about one fill volume of relatively acidic liquid and one fill volume of relatively basic liquid. In exemplary configurations, a fill volume may correspond to about 1.2 gallons of water. 
         [0025]    As more specifically seen in  FIG. 2 , electrolysis cells  202 ,  204 ,  206 ,  208  form an electrolysis system  200  that, as a voltage supply is coupled between anode electrode  210  and cathode electrode  212 , converts water supplied to electrolysis cells  202 ,  204 ,  206 ,  208  into acid and base ionized liquids for storage in chambers  232 ,  234 , respectively. Anion and cation exchange membranes  222 ,  224 ,  226  are used to separate and transport protons and hydroxyl ions to the acid and base chambers  232 ,  234 . In an exemplary configuration, an alkaline dish wash liquid having a pH of about 11 and an acidic rinse having a pH range of about 2.5 to 4 may be employed. The acidic rinse not only assists in managing scaling and filming (spotting) on the dishes but also on the dishwasher hydraulic system. An acidic rinse also acts as a sanitization agent in the dishwashing operation. 
         [0026]    More generally, as illustrated in  FIG. 3 , water from the tap is introduced into acid and base tanks  332 ,  334 , respectively, of electrolysis system  300  with about one fill volume of water in each tank for a total of about two fill volumes. Once the tanks have been filled with the required amount of water, the electrolysis process starts. 
         [0027]    With reference now to  FIGS. 2 and 3 , it will be seen that an exemplary electrolysis cell  200 , may include two inlets and two outlets with one set, i.e., one inlet and one outlet, provided for base and another one for acid generation. Tanks  232 ,  234 ,  332 ,  334  are connected to the electrolysis cell through independent pumps and particle filters  342 ,  344  to remove solid particles from water to avoid clogging of electrolysis cell. In an exemplary configuration, pumps  342 ,  344  may be configured for operation at 12 VDC. It will be appreciated by those of ordinary skill in the art that pumps operating at other voltages may also be used. 
         [0028]    A power supply (not separately illustrated) coupled to the electrodes  210 ,  212  of the electrolysis cell is provided and may correspond in an exemplary configuration to a 12 VDC supply. Again, it should be appreciated that other voltage levels may be used. Power is supplied simultaneously to the pumps and electrolysis cell, and the electrolysis process starts. As generally illustrated in  FIG. 4 , the pH level  444  of water in base tank  334  slowly increases and the pH level  442  in acid tank  332  decreases. Once the required level of pH is achieved, the process stops. As generally indicated on  FIG. 4 , this process may require from about twenty to thirty minutes to complete. During the main wash cycle, water from base (alkaline) tank  334  is used for washing the dishes while during one of the rinse cycle, water from acid tank  332  is used as an acid rinse. 
         [0029]    With reference to  FIG. 5 , there is illustrated a block diagram representing pre-wash, filtration, and regeneration processes  500  in accordance with present technology. One of the important aspects of the present subject matter involves soil separation system  502 . In accordance with present disclosure, the soil separation system  502  includes two filtration or separation portions: a sediment-water separation portion  504  and an oil-water separation portion  506 . 
         [0030]    Within sediment-water separation portion  504 , two filters, a 150 micron (μ) filter  510  and a 5μ filter  512 , are used to remove sediments from used pre-wash water. 150-micron filter  510  may correspond to a nylon mesh filter which effectively removes loose food particles from used water. 5μ filter  512  removes particle size of 5-micron and above and helps to prevent clogging of Kapok filter  514  which corresponds to the previously noted oil-water separation portion  506 . Kapok filter  514  helps to filter oil from water. Ultra and/or nano filtration can also be added to the sediment filtration to obtain cleaner water for re-cycling. 
         [0031]    Kapok is a natural material that comes from the Kapok tree, also known as Ceiba pentandra, Ceiba, or Silk Cotton Tree and has hydrophobic and oleophilic surface characteristics. The surface characteristic of the kapok fiber helps to retain oils while permitting water to pass, thereby producing the desired separation of oil from water. Each of the filters  510 ,  512 ,  514  may be regenerated via reverse flushing at the end of each cycle to prepare them for the next cycle. This process can be effectively used in various applications where there are suspended particles, oil and grease contaminations which need to be separated and flush to the drain system. 
         [0032]    Referring to  FIGS. 6 and 7 , an exemplary dishwashing cycle in accordance with present technology will be described. First, however, with reference to  FIG. 7 , it will be noticed that there is representatively illustrated a controller  700 . Further, the schematic representation of the dishwasher system illustrated in  FIG. 7  illustrates a number of connecting lines that generally represent tubes or piping configured to provide fluid flow paths. The various illustrated valves V 1 -V 9  and pumps P 1 -P 5  are controlled by controller  700  to direct fluid flow within the dishwasher. Those of ordinary skill in the art will appreciate that controller  700  may take on various forms including, for example but not limited to, a timer motor driven switching mechanism, a computer operated controller, a microprocessor, or other electro-mechanical device. Further, with respect to the variously illustrated valves V 1 -V 9 , it will be readily apparent to those of ordinary skill in the art that certain of these valves, for example V 2 , V 6 , and V 8  are configured to simply be open or closed to block or permit fluid flow. Others of the valves, for example V 1 , V 3 , V 4 , V 5 , and V 6  may be operated to block or direct fluid flow in different flow paths. These paths will be readily apparent to those of ordinary skill in the art in conjunction with the following operational description. 
         [0033]    The dishwashing cycle begins with a water fill  602  from base tank  1  ( FIG. 7 ) or fresh water from a tap into Main Tank  704 . Water from base tank  1  corresponds to water saved from previous rinse water. A first pre-wash  604  starts and at the same time tap water from source  702  is sent to electrolysis cell  706  at step  606 . An electrolysis cycle begins at step  608  after about 2.4 gallons of water is introduced into electrolysis cell  706 . 
         [0034]    At step  610  the first pre-wash cycle ends and a sediment and oil filtration step begins. At this point water from the first pre-wash is recycled with the help of filtration system including filters  710 ,  712 ,  714  and the same water is used for a second pre-wash starting at step  612 . Pre-wash stops at step  614  and again the pre-wash water is filtered by filters  710 ,  712 ,  714  and used again a third pre-wash at step  616  and yet another filtering at step  618  when the third pre-wash is stopped. In accordance with present technology, these three pre-wash cycles including filtration and reuse of the water provide a saving of ⅔ of pre-wash water consumption. 
         [0035]    Water from the tap  702  or base tank  1  (previous rinse water) is taken into main tank (sump)  704  of the dishwasher for pre-washing. Once the sump has been filled with a required amount of water, spraying starts for the pre-wash cycles to remove loose food particles, oil and grease from the dishware. After specified times of spraying, the pre-washing stops and the filtration process starts. Water will pass through 150 micron filter  710 , 5 micron filter  712 , and kapok filter  714  and back to sump  704 . This is a dilution process, so the filtration process continues until most of the soils are separated from the water. Once the filtration process is completed, spraying starts again for further pre-washing the dishes. This cycle continues, through a third pre-wash cycle. At the end of this process, used water will reverse flush through 5 and 150-micron filters  712 ,  710 , respectively, for regeneration. Kapok filter  714  is spun at high speed (step  622 ), which enables centrifugal extraction of oil at the end of this drain cycle  620 . At this time the electrolysis process is stopped (step  624 ) and base water from base tank  1  is sent to main dishwasher cabinet  704  (step  626 ). 
         [0036]    Following the three pre-wash cycles, the main (alkaline) wash is started (step  628 ) using water from Base tank  1 . During this process a heater within dishwasher cabinet  704  is turned on to heat the wash water to about 130° F. After a predetermined washing period, the alkaline wash is stopped at step  630  and a sediment filtration process starts using 5 and 150-micron filters  712 ,  710  to circulate the water from Base tank  1  through cabinet  704 . Following filtration, the used alkaline water is moved to base tank  1  (step  632 ) and acid water is added to cabinet main sump  704  (step  634 ) from acid tank  2  to start an acid rinse cycle (step  636 ). 
         [0037]    Following the acid rinse cycle, used acid water is moved from main sump  704  to acid tank  2  (step  638 ) and the alkaline water previously moved in step  632  to base tank  1  is sent (step  640 ) to main sump  704  and base tank  1  is acid flushed (step  642 ) with water from acid tank  2 . 
         [0038]    Acid sediment filtration flushing (step  644 ) is then performed by pumping water from acid tank  2  through base tank  1  and 5 and 150-micron filters  712 ,  710  to drain  708 . Kapok filter  714  is then spun by a spin motor  716  (step  646 ) and drained into drain  708  along with alkaline water. Tap water from source  702  is then sent to main sump  704  (step  648 ) in preparation for a final rinse at step  650 . during the final rinse, the heater within main sump  704  is controlled to operate at about 150° F. Upon completion of the final rinse, the rinse water in main tank  704  is moved to base tank  1  for storage or drained out of the dishwasher and the wash cycle ends (step  654 ). 
         [0039]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.