Patent Publication Number: US-2010116689-A1

Title: Systems and Methods for Controlling Ion Deposition

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 61/112,705 filed on Nov. 7, 2008 in the United States Patent and Trademark Office entitled “Method and Apparatus for Controlling Silver Ion Deposition.” The entire disclosure of U.S. Provisional Patent Application Ser. No. 61/112,705 is incorporated herein by reference as if fully disclosed. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to a system and method for controlling an ion concentration, and more particularly controlling the concentration of silver ions that are released into the wash water of a laundry appliance. 
     BACKGROUND 
     Silver is widely known for its antibacterial properties when used in a washer appliance. Silver ions may be trapped in fabric to provide ongoing protection against odor-causing bacteria. Previous known methods for releasing silver ions into wash water have been the use of electrolysis of metallic silver by means of a voltage or current source. This is typically implemented by positioning two parallel silver rods into the flow of water supplying the laundry appliance. An electrical potential is applied across the two rods causing an electrical current to pass between them thereby ionizing the silver particles on the surface of the rods. The ionized silver particles are then released into the water stream. The rods are typically sealed inline with the plumbing of the apparatus and should be replaced before they erode to the point of creating a path for water to leak outside the system. 
     The conductivity of the water affects the concentration of silver ions released into the water when a fixed voltage or fixed current is applied to the silver rods. Unfortunately, for many household environments, the conductivity of the water supplied to a washing appliance is not constant, and the total dissolved solids (“TDS”) can range anywhere from 30 parts per million (“ppm”) to over 800 ppm. In many cases, because of the variation of the conductivity and the total dissolved solids in the water, the silver ion concentration can range anywhere from a few parts per billion (“ppb”) to well over 300 ppb. 
     Thus, there exists a need for a system and method to ensure a relatively constant concentration of silver ions to be released into a flow of water regardless of the conductivity of the water used in the electrolysis process. 
     SUMMARY 
     Embodiments of the present disclosure generally provide systems and methods of controlling an ion concentration in water, for example, a silver ion concentration. The method of depositing ions in the water includes determining a conductivity level of the water using a reference probe. A power level based on the determined conductivity level is also determined. Power is applied to a deposition probe corresponding to the determined power level using a first electrical circuit, and a concentration of ions are deposited in the water. 
     In one embodiment, the present disclosure could allow a relatively constant silver ion concentration to be released into a water stream regardless of the conductivity of the water used in the electrolysis that ionizes the silver on a deposition probe. 
     In one embodiment, the present disclosure could also allow a user to be notified if deposition rods used in the electrolysis have worn to a certain point. For example, a user may notified when deposition rods have worn past a mid-point, and also notified when the deposition rods have worn past a point when they may no longer be effective and should be replaced. 
     Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic of an ion deposition system coupled to a water source and a washer appliance according to one embodiment of the present disclosure; 
         FIGS. 2A-2C  illustrate isometric views of the deposition probe of  FIG. 1  at various stages of wear according to one embodiment of the present disclosure; 
         FIG. 3  illustrates a flow diagram of a method for controlling the concentration of ions deposited in water according to one embodiment of the present disclosure; 
         FIG. 4  illustrates a flow diagram of a method for determining and alerting a user of the wear level of the deposition probe of  FIG. 1  according to one embodiment of the present disclosure; and 
         FIG. 5  illustrates a schematic of a circuit used to control the concentration of ions deposited in water according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure generally provides systems and methods for depositing ions in water supplied to a washer appliance, such as depositing silver ions into the water. According to the teaching of this disclosure, the ion concentration may be held generally constant regardless of the conductivity of the water or the wear of a deposition probe as a result of electrolysis. In certain embodiments, a silver ion concentration of approximately 20 parts per billion (“ppb”) may be a desired level to ensure that enough silver ions are deposited in the wash water to be effective, but not too many silver ions are deposited such that the effectiveness may be reduced. 
       FIG. 1  generally illustrates a schematic of an embodiment of an ion deposition system  100  according to one embodiment of the present disclosure. It should be understood that system  100  shown in  FIG. 1  is for illustrative purposes only and that any other suitable system or subsystem could be used in conjunction with or in lieu of system  100  according to one embodiment of the present disclosure. The ion deposition system  100  deposits metallic ions in water. For example, the ion deposition system may deposit silver ions in a flow of water demanded by a washer appliance  118 . Silver ions may have beneficial properties in killing bacteria and cleaning laundry, in addition to, or in lieu of detergent. 
     The ion deposition system  100  receives water from a water source  102 . The water source  102  may be a conventional cold water line that supplies water for use by the residential washer appliance  118 . In a flow line with the water source  102  may be a flow switch  104 . The flow switch  104  may communicate with a control circuit  114 , which may determine if water is flowing through the ion deposition system  100  as a result of a demand from the washer appliance  118 . If the control circuit  114  determines that water is flowing through ion deposition system  100 , it may allow power to be supplied to the system  100 . If the control circuit  114  determines that no water is flowing to the ion deposition system  100 , it can shut off the power to the ion deposition system  100 . 
     A pair of probes positioned in-line with the water flow may receive water flowing past flow switch  104 . A reference probe  106  may provide information as to the conductivity of the water, and a deposition probe  110  may release silver ions in the water when it is subjected to electrolysis. The reference probe  106  may include a pair of reference rods  108 . The reference rods  108  may be made of a non-corrosive metallic material, and the electrical resistance provided by the reference rods  108  may indicate a conductivity of the water. The conductivity of the water may depend on the concentration of total dissolved solids (“TDS”) in the water. Total dissolved solids may include inorganic salts, such as calcium, magnesium, potassium sodium, bicarbonates, chlorides, and sulfates. TDS may also include small amounts of organic matter that are dissolved in the water. Most of these substances are associated with the water&#39;s hardness and bitter taste. Their presence may also lead to corrosion or encrustation in water-distribution systems. In a household environment, the concentration of total dissolved solids may range from 30 parts per million (ppm) to 800 ppm. For example, tap water typically has a TDS concentration of approximately 70 ppm. When the concentration of total dissolved solids is high the water has a higher conductivity. In contrast, when the TDS level is lower, the water has a lower conductivity. Water with a higher conductivity will cause more silver ions to be released when the deposition probe  110  is subjected to electrolysis if the deposition probe  110  voltage is held constant. Thus, it is beneficial for the system  100  to cause a relatively constant number of silver ions to be released into the water regardless of the conductivity of the water. For example, a silver ion concentration of approximately 20 ppb may be desirable. 
     The deposition probe  110  may include deposition rods  112 . The deposition rods  112  may be coated with or a solid metallic material that ionizes when subjected to electrolysis. For example, the deposition rods  112  may be coated with silver and release silver ions into the water when subjected to electrolysis. The current required to ionize the deposition rods  112  may come from a current source controlled by a control circuit  114 . In certain embodiments, the current source may be a variable current source to allow different current levels to be supplied to the reference probe  106  or the deposition probe  110 . The control circuit  114  may determine how much current or power to supply to either the deposition probe  110  or the reference probe  106 . The control circuit  114  may also use a feedback voltage and a feedback current returned from the reference probe  106  to determine a reference probe resistance provided by the reference probe  106 . This resistance may allow the control circuit  114  to determine the conductivity level of the water and use this determination in further calculations, such as the calculation of the current to be supplied to the deposition probe  110  to deliver the desired power level. Likewise, the control circuit  114  may also use a feedback voltage and a feedback current returned from the deposition probe  110  to determine the resistance of the deposition probe  110 . This resistance determination may also be used in further calculations, such as in a calculation to determine the degradation or wear of deposition rods  112 . The control circuit  114  may also reverse the polarity of a voltage across the deposition probe  110  after a predetermined time, such as ten seconds. This continuous reversal of the polarity may ensure that each of the deposition rods  112  degrade or wear evenly. 
     In certain embodiments, the ion deposition system  100  may also include a switch  116 . When the switch  116  is in a first position making an electrical connection with the reference probe  106 , current from the current source may be supplied to the reference probe  106 . When the switch  116  is in a second position making an electrical connection to the deposition probe  110  (as shown in  FIG. 1 ), current from the same current source may be supplied to the deposition probe  110  causing electrolysis of the deposition rods  112  and releasing silver ions into the water. Thus, according to the teachings of the present disclosure, the ion deposition system  100  may ensure that a constant concentration of silver ions is received by washer appliance  118  regardless of the conductivity of the water or the wear of the deposition rods  112 . 
       FIGS. 2A-2C  generally illustrate embodiments of the deposition probe  110 . It should be understood that the deposition probe  110  shown in  FIGS. 2A-2C  is for illustrative purposes only and that any other suitable system or subsystem could be used in conjunction with or in lieu of deposition probe  110  according to one embodiment of the present disclosure. The deposition probe  110  may include a threaded portion  122  to allow the deposition probe  110  to be inserted into the water flow with a watertight seal. The threaded portion  122  may also allow the deposition probe  110  to be easily unscrewed for removal and replacement. The deposition probe  110  may also include an electrical connection  120 . The electrical connection  120  may allow deposition probe  110  to be connected to the current source and the control circuit  114 . 
     The deposition probe  110  includes deposition rods  112 . In certain embodiments, the deposition rods  112  may be a set of plates or tubes or any other configuration of material that will allow electrolysis and ionization of material on deposition rods  112 .  FIGS. 2A-2C  illustrate the deposition rods  112  at increasing stages of degradation or wear. The deposition rods  112   a  shown in  FIG. 2A  may be that of a new deposition probe  110 . The deposition rods  112   a  may have a length of approximately 2.75 inches.  FIG. 2B  illustrates an aged deposition probe  110  with aged deposition rods  112   b.  The deposition rods  112   b  may be shorter and have less mass than deposition rods  112   a  because they have been subjected to a certain period of use and have been subjected to numerous events of electrolysis causing the material of the deposition rods  112   a  to be released into the water supplying the washer appliance  118 . For example, deposition rods  112   b  may be 1.8 inches long. Similarly, deposition rods  112   c  may be even shorter and have less mass than deposition rods  112   b  because they have been subjected to an even longer period of use and even more events of electrolysis. The length of deposition rods  112   c  may be a half of an inch. When deposition rods  112   c  wear to approximately a half of an inch, they may need to be replaced to ensure proper operation of ion deposition system  100  in accordance with the teachings of the present disclosure. 
       FIG. 3  is a somewhat simplified flow diagram illustrating method  300  of controlling the concentration of silver ions deposited in a flow of water supplying a washer appliance  118 . It should be understood that method  300  shown in  FIG. 3  is for illustrative purposes only and that any other suitable method or sub-method could be used in conjunction with or in lieu of method  300  according to one embodiment of the present disclosure. It should also be understood that the steps of method  300  could be performed in any suitable order or manner. 
     The method  300  begins at step  302  where it is determined if water is flowing to the washer appliance  118 . This determination may be made by the control circuit  114  via input from the flow switch  104 , which determines if water is flowing through the ion deposition system  100 . If no water is flowing, then the method ends, as there is no water to release silver ions into. If the water is flowing, at step  304  a momentary test current is passed through the reference probe  106  using a first current source that is part of a first electrical circuit. Next, at step  306  a conductivity level of the water is determined by using the reference probe. The conductivity level may correspond to a concentration of total dissolved solids in the water received from the source. The test current may cause a feedback voltage and a feedback current to be returned to the control circuit  114 . Using this feedback voltage and feedback current, the control circuit  114  may determine a resistance caused by the reference probe  106 . This resistance may be used to determine the conductivity of the water. 
     At step  308 , a level of power to deliver to the deposition probe  110  may be determined based on the determination of the conductivity of the water. If a high conductivity of the water is determined then the power supplied to the deposition probe may be lower to keep the concentration of silver ions in the water relatively constant. Thus, there may be an inverse relationship of power to the deposition probe  110  to the conductivity of the water. At step  310 , the power level determined at step  308  may be regulated and supplied to the deposition probe  110 . This power may be delivered by the same source that supplied the test current to the reference probe in step  304 . 
     At step  312 , it may be determined whether a predetermined time has elapsed. In certain embodiments, it may be determined if 10 seconds has elapsed. If 10 seconds has not elapsed then the polarity of the voltage across the deposition probe  110  is not changed and the method returns to step  310 . If the predetermined time has elapsed, then the polarity of the voltage across the deposition probe  110  is reversed at step  316 . This reversal allows the two deposition rods  112  to release ions at an even rate. Thus, each deposition rod  112  will wear approximately evenly. 
     It is determined whether the water is still flowing to the washer appliance  118  at step  318 . If the water is still flowing, then the method  300  returns to step  310  and power continues to be supplied to the deposition probe  110 . If the water is not still flowing, then the power to the deposition probe  110  is shut off at step  320  and the method ends. 
       FIG. 4  is a somewhat simplified flow diagram illustrating a method  400  of determining the wear of the deposition rods  112  in accordance with one embodiment of the present disclosure. It should be understood that method  400  shown in  FIG. 4  is for illustrative purposes only and that any other suitable method or sub-method could be used in conjunction with or in lieu of method  400  according to one embodiment of the present disclosure. It should also be understood that the steps of method  400  could be performed in any suitable order or manner. 
     The method  400  begins at step  402  when power is supplied to the deposition probe  110 . Once the power is supplied to the deposition probe  110 , a feedback voltage and feedback current may be used by the control circuit  114  to determine a resistance of the deposition probe  110 . In certain embodiments, a feedback voltage and feedback current received from the reference probe  106  may be used to determine a resistance of the reference probe  106 . This resistance may be used as a baseline resistance that takes into account the conductivity of the water in the determination. The reference probe  106  resistance may be used to calculate a first and a second predetermined value and compared to the deposition probe  110  resistance, which also may be dependent on the conductivity level of the water. 
     At step  406 , it is determined if the resistance of the deposition probe  110  is less than a first predetermined value. For example, in an embodiment where the conductivity level of the water corresponds to approximately 500 ppm, a resistance of approximately 185 ohms may be determined. This resistance may be less than a predetermined value of approximately 400 ohms, which may indicate that the deposition rod  112  length is greater than 1.8 inches, and therefore the deposition probe  110  is not in need of replacement. Thus, if the resistance is less than a first predetermined value, a first color of a signal lamp may be illuminated at step  408 , which may indicate to the user that the deposition probe  110  is in an optimal operating condition because it still has sufficient material to release ions into the water. 
     If the deposition probe  110  resistance is not less than a predetermined value, then the method proceeds to step  410 . At step  410 , it is determined if the deposition probe  110  resistance is less than a second predetermined value. If the resistance of the deposition probe  110  is less than the second predetermined value, but greater than the first predetermined value, then a second color of a signal lamp may be illuminated at step  412 . This second color may signal to the user that the deposition rods  112  have worn past their optimum length and can be subjected to more electrolysis, but the deposition probe  110  may soon need to be replaced. For example, the deposition probe  110  resistance of approximately 500 ohms may be determined. This may be less than the predetermined value of 850 ohms, and may correspond to a length of deposition rods  112  that is less than 1.8 inches but greater than 0.5 inches. 
     If the deposition probe  110  resistance is not less than the second predetermined value, then the method proceeds to step  414 . At step  414 , power to the deposition probe  110  may be switched off, and a third color of the signal lamp may be illuminated at step  416 . It should be understood that this disclosure is not limited to only illuminating a signal lamp to convey a message regarding the length and wear of deposition rods  112  to the user, and any display that can convey a message to a user may be used in accordance with the present disclosure. For example, in certain embodiments, a screen may display a verbal message to the user. The illumination of the third color of the signal lamp at step  416  and shutting off the power to the deposition probe  110  may result when deposition rods  112  are less than 0.5 inches long. Deposition rods  112  that are less than 0.5 inches long may be in need of immediate replacement because there may not be sufficient material on the deposition rods  112  to allow sufficient electrolysis according to the teaching of the present disclosure. Furthermore, power may be shut off to the deposition probe  110  to eliminate any chance that the user is able to continue to operate the system  100  when the length of the deposition rods  112  are so short. In certain embodiments, the deposition probe  110  may be replaced at step  418 , causing the third signal lamp to be turned off at step  420 , where the method ends. 
       FIG. 5  shows a schematic of a circuit  500  for controlling the concentration of ions released in water as a result of electrolysis of the deposition probe  110  in accordance with the teachings of the present disclosure. Among other components, the circuit  500  may be comprised of the control circuit  114 , the deposition probe  110  (labeled H2 Silver Probe in  FIG. 5 ), and the reference probe  106  (labeled H 2  TDS Probe in  FIG. 5 ). 
     Control circuit  114  may be a microcontroller circuit. It may operate as a part of a closed loop system with the surrounding circuits to function primarily as a precision low power regulator to deposition probe  110 , where the deposition probe  110  power can range from 5-30 mW depending on the conductivity of the water. Regulation may be achieved by controlling a current source circuit  515  with a 10-bit high-resolution pulse width modulation circuit  516 . Inputs from polarity circuit  508  and deposition/reference circuit  510  may be processed by control circuit  114  to calculate the differential voltage across deposition rods  112  and reference rods  108 , as well as the respective reference or deposition probe current. These calculations may be further processed to determine power and resistance used for determining the condition of deposition rods  112 , the water conductivity, and the appropriate power for deposition rods  112  to release the desired amount of silver ions into the water stream. 
     Control circuit  114  may be coupled to a current sensor circuit  504 , a voltage sensor circuit  506 , a polarity circuit  508 , and a deposition/reference probe circuit  510 . The current sensor circuit  504  may receive a feedback current from the deposition probe  110  or the reference probe  106 . Similarly, the voltage sensor circuit  506  may receive a feedback voltage from deposition probe  110  or reference probe  106 . Polarity circuit  508  may control switching the polarity of the voltage across the deposition probe  110 . The deposition/reference probe circuit  510  may be coupled to the deposition probe  110  and the reference probe  106  and may control the routing of power to each. The circuit  500  may also include a switching circuit  512 . This switching circuit  512  may generally correspond to switch  116  shown in  FIG. 1 . In the example embodiment shown, switching circuit  512  is a double pole, double throw switch, which allows the same power source to supply deposition probe  110  or reference probe  106 . Circuit  500  also includes a power booster circuit  514 . The power booster circuit  514  may be an integrated circuit that increases a 12-volt supply to a 22-volt supply. In certain embodiments, power booster circuit  514  may be a dedicated analog device. 
     It may be advantageous to set forth definitions of certain words and phrases used in this patent document. The term “couple” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. 
     While this disclosure has described certain embodiments and generally associated methods, alterations, and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.