Abstract:
A method for dispensing a first treating agent and a second treating agent into the washing tub of a dishwasher includes providing each of first and second reservoirs with a sensor for monitoring its fill level. After a first dispensing operation, a controller compares the sensor signals and determines whether a ratio of the fill levels deviates from a ratio of the capacities of the reservoirs. The controller elects either a standard or an alternative subsequent dispensing operation based on whether the fill level ratio deviates from the capacity ratio. The controller chooses the standard subsequent dispensing operation if the fill level ratio does not deviate from the capacity ratio and chooses the alternative subsequent dispensing operation if it does. The alternative subsequent dispensing operation includes changing at least one amount dispensed by dispensing devices compared to a corresponding amount dispensed in the first dispensing operation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is claimed to German Patent Application No. DE 10 2008 032 363.2, filed Jul. 10, 2008, the entire disclosure of which is incorporated by reference herein. 
       FIELD 
       [0002]    The present invention relates to a method for dispensing a first treating agent and a second treating agent into the washing tub of a dishwasher including a first reservoir and a first dispensing device corresponding to the first treating agent, and a second reservoir and a second dispensing device corresponding to the second treating agent. 
         [0003]    German Patent Application DE 10 2005 059 343 A1 describes a method for dispensing cleaning agent and bleaching agent into the washing tub of a dishwasher, in which method two separate reservoirs of different capacities are provided, and in which the cleaning agent and the bleaching agent are dispensed during a wash cycle in quantities whose ratio is equal to the ratio of the capacities of the reservoirs. Since two different treating agents are used during a wash cycle, it is desirable to be able to refill the two agents at the same time in one operation. To this end, the empty volume available in each reservoir must be sufficient to receive a predetermined refill quantity which is generally equal to or greater than the capacity of a supply container of such an agent. The volume to be used for one cycle can be controlled in different ways, such as by the ON time of a dispensing pump, the opening time of an outlet valve, or the size of a dispensing chamber. German Patent Application DE 10 2005 059 343 A1 uses a dispensing system having a dispensing chamber that can be closed off from both the reservoir and an outlet port. This makes it possible to fill the dispensing chamber, or to discharge a fluid contained in the dispensing chamber, as needed. All of the conceivable methods for controlling an amount to be dispensed are encumbered with tolerances. Such tolerances may cause the dispensing chambers to empty at different rates in an unwanted manner. Also, failure to completely empty a supply container, or failure to completely fill a reservoir for other reasons may cause the respective reservoir to empty before the other. 
         [0004]    EP 1 329 187 A2 describes a combination dispenser for receiving detergent for one wash cycle and rinse aid for multiple wash cycles. 
       SUMMARY 
       [0005]    An aspect of the present invention is to provide a method for dispensing a first treating agent and a second treating agent into the washing tub of a dishwasher, which method allows at least two reservoirs to empty at substantially the same time, even if tolerance-related deviations occur during the dispensing process. 
         [0006]    In an embodiment, the present invention provides a method for dispensing a first treating agent and a second treating agent into the washing tub of a dishwasher. The dishwasher includes a first reservoir and a first dispensing device corresponding to the first treating agent and a second reservoir and a second dispensing device corresponding to the second treating agent. The method includes providing each of the first and second reservoir with at least one sensor for monitoring a fill level of the respective reservoir. After a first dispensing operation, the first and second sensor signals corresponding to the at least one sensor of the respective first and second reservoirs are compared using a controller. Based on the first and second sensor signals, the controller is used to determine whether a first ratio of a fill level of the first reservoir to a fill level of the second reservoir deviates from a second ratio of a capacity of the first reservoir to a capacity of the second reservoir. Based on the determining, one of a standard and alternative subsequent dispensing operation is elected. The standard subsequent dispensing operation is elected if the first ratio does not deviate from the second ratio and the alternative subsequent dispensing operation is elected if the first ratio does deviate from the second ratio. The standard subsequent dispensing operation includes controlling, with the controller, the first and second dispensing devices so as to dispense a first amount from the first dispensing device and a second amount from the second dispensing device, the first and second amounts so as to dispense a first amount of the first dispensing device and a second amount from the second dispensing device. A ratio of the first amount to the second amount is substantially equal to the ratio of the capacities of the first and second reservoirs. The alternative subsequent dispensing operation includes changing at least one amount dispensed by the first and second dispensing devices compared to a respective corresponding amount dispensed in the first dispensing operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]    The present invention will be explained in more detail below with reference to an exemplary embodiment and the accompanying drawings, in which: 
           [0008]      FIG. 1  is a schematic view of the front side of a household dishwasher configured in accordance with an embodiment the present invention; 
           [0009]      FIG. 2  is a cross-sectional view through the upper portion of the appliance door of the household dishwasher shown in  FIG. 1 ; 
           [0010]      FIG. 3  is a schematic view of a system for dispensing two treating agents; and 
           [0011]      FIG. 4  is a timing diagram of various sensor signals and state variables during the execution of the method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0012]    The monitoring of the fill level in each reservoir by at least one sensor enables a controller to determine, after a dispensing operation, from the sensor signals whether the ratio of the fill level of the first reservoir to that of the second reservoir deviates from the ratio of the capacity of the first reservoir to that of the second reservoir. This allows the dispensed amounts to be controlled by the controller in such a manner that the amounts intended to be dispensed are maintained in a subsequent dispensing operation if the ratio of the fill level of the first reservoir to that of the second reservoir does not deviate from the ratio of the capacity of the first reservoir to that of the second reservoir. However, if it is established that the ratio of the fill level of the first reservoir to that of the second reservoir deviates from the ratio of the capacity of the first reservoir to that of the second reservoir, then the amounts intended to be dispensed can be changed by the controller for the subsequent dispensing operation, it being alternatively possible to change only one amount to be dispensed or both amounts to be dispensed. Thus, the amounts to be dispensed can be adjusted in a manner that allows the first and second reservoirs to empty at substantially the same time, even if emptying has occurred unevenly because of tolerances in the dispensing of the treating agents, as a result of which an amount different from a predetermined target amount has been dispensed. Accordingly, the controller exerts a compensating effect to achieve simultaneous emptying and thereby allow the user to refill both treating agents in one operation. 
         [0013]    In one embodiment, each reservoir is provided with only one sensor, and each sensor monitors a discrete fill level with a predetermined residual volume. In order to have sufficient capacity to compensate for the dispensing error, the residual volume is about 20% of the capacity of the respective reservoir. This also ensures that the dispensing of the treating agents is not corrected until the reservoir can actually be expected to empty soon. This makes it possible to dispense the targeted amount of the respective detergent for more than half the volume of the reservoir. 
         [0014]    When the monitored fill level is reached, the amount to be dispensed may be reduced, for example, by 10% to 50% compared to the previously dispensed amount, thereby adjusting the instantaneous amount. Alternatively, or additionally, it is possible to increase the amount to be dispensed from the other reservoir by 10% to 50% compared to the previously dispensed amount once the monitored fill level is reached. This allows the instantaneous amounts to be adjusted in a particularly effective manner, especially when a deviation is detected between the empty volumes of the two reservoirs. 
         [0015]    According to another embodiment, the controller counts the dispensing operations for which the amounts intended to be dispensed are changed until the fill levels monitored by the sensors are reached in both reservoirs. Using this information, the controller can determine with at least approximate accuracy the magnitude of the error that occurred during the dispensing process and, once the fill levels monitored by the sensors are both reached, the controller, based on the number of dispensing operations detected by the controller to have been performed with a changed amount, can then cause an additional number of dispensing operations to be performed also with a changed amount. Using suitable statistical methods, it can then be ensured that both reservoirs empty at approximately the same time. 
         [0016]    In one embodiment, when or shortly before the reservoirs have reached an empty level, an alert is issued, prompting the user to refill the two reservoirs. This increases the ease-of-use, because the user must perform the refilling of the reservoirs only once, thereby avoiding separate filling. 
         [0017]      FIG. 1  shows the front side of a household dishwasher  1 , which is known to include a washing tub  2  which is open at the front and can therefore be closed by a hinged appliance door  3 . This figure shows the appliance with the door  3  closed. Therefore, washing tub  2 , which is fragmentarily shown in  FIG. 2 , cannot be seen in  FIG. 1 . The upper portion of door  3  may accommodate a control panel  4  containing a rotary selector switch  5  and/or push buttons  6  for cycle selection and further containing indicators  7  used to display information to the user. A controller  8  and further electrical and electronic components are disposed inside the control panel, which is symbolized by the dashed-line box. As can be seen in  FIG. 2 , door  3  is formed of an outer door panel  9  and an inner door panel  10 . Inner door panel  10  has a folded edge  11 , so that a closed hollow body  12  is formed when outer door panel  9  and inner door panel  10  are assembled together. The dispensing systems and reservoirs, which will be described hereinafter, are disposed within this hollow body  12 , and are therefore indicated as dashed-line shapes. The valves, hose connections, and electrical wires, etc., which are also needed, are not the subject matter of the present invention and are therefore not shown here. The middle portion of the door accommodates a so-called combination dispenser  13 , said combination dispenser being capable of receiving powdered detergent or detergent tabs for one wash cycle and of receiving rinse aid for several wash cycles. There may also be provided a salt container  14  to receive the water softener salt necessary to regenerate a water softener. In accordance with the present invention, a further dispensing system  15  is disposed in the upper left half of appliance door  3 . 
         [0018]    Further dispensing system  15  is capable of discharging liquid or pasty cleaning agent and liquid or pasty bleaching agent in a program-controlled manner.  FIG. 3  shows said further dispensing system purely schematically. The active components are stored separately in two different reservoirs, namely reservoirs  20  and  30 . Thus, the enzymatic/alkaline and bleaching components, which are incompatible in liquid and/or pasty formulations, are not mixed until they are in the washing tub, where they can then produce their full effect. 
         [0019]    First reservoir  20  has connected thereto a dispensing device including a dispensing chamber  24 , a valve  25  being disposed between reservoir  20  and dispensing chamber  24 , and a valve  26  allowing dispensing chamber  24  to be closed off on the side that faces an outlet port. Valves  25  and  26  are controllable by an actuating element  27 . Similarly, the outlet side of reservoir  30  is connected via a valve  35  to a dispensing chamber  34 . When a valve  36  is open, dispensing chamber  34  can discharge the second treating agent through an outlet port. Valves  35  and  36  are controlled by a second actuating element  37 . 
         [0020]    It is also possible to provide dispensing devices which use a dispensing pump, in which an outlet valve is opened for a predetermined period of time, or in which other fluid-delivery devices are provided. 
         [0021]    In order to dispense a first and second treating agent, initially, valves  25  and  35  are opened, allowing the respective treating agent to flow into dispensing chamber  24  or  34 , respectively. The metered dose corresponds to the size of dispensing chambers  24  or  34 , respectively. When the two dispensing chambers  24  and  34  are full, valves  25  and  35  are closed, and valves  26  and  36  at the outlet port are opened to start the dispensing operation. In this manner, the two treating agents are added into the washing tub of a dishwasher. After that, valves  26  and  36  are closed. This dispensing cycle is repeated until a predetermined amount has been dispensed. The capacities of reservoirs  20  and  30  are matched to the amounts to be dispensed, so that, for example, an amount of a first treating agent can be added twenty times, and a correspondingly larger or smaller amount of the second treating agent in reservoir  30  can also be added twenty times as a target amount. This is possible because the amounts are proportional to the capacities of the respective reservoirs, so that when accurate amounts are dispensed, reservoirs  20  and  30  will empty at the same time. 
         [0022]    In order to check whether the desired amounts of the first and second treating agents were actually dispensed, or whether there are noticeable deviations, reservoir  20  is equipped with a first sensor  22  capable of indicating a predetermined fill level  21  which indicates that no more than a predetermined residual volume  23  remains in reservoir  20 . Similarly, the reservoir  30  is provided with a sensor  32  which is capable of detecting a fill level  31 . Sensor  32  makes it possible to detect a residual volume  33 . Residual volumes  23  and  33  are selected to be proportional to the volumes of reservoirs  20  and  30 ; i.e., the ratio of the two residual volumes  23  and  33  is equal to the ratio of the capacities of the two reservoirs  20  and  30 . 
         [0023]    Sensors  22  and  32  can take the form of threshold switches which output signals to controller  8  when the respective fill levels  21  and  31  are reached. 
         [0024]    If, for example because of tolerances or unequal filling, reservoirs  20  and  30  do not empty evenly, controller  8  can adjust the amounts to be dispensed, since it is beneficial for the user if the two reservoirs  20  and  30  reach a reserve volume, or empty, at the same time, because then both reservoirs  20  and  30  can be filled at the same time. When doing this, it should be possible to pour an entire refill container into the reservoir. Therefore, it is advantageous for the user not to be prompted to refill the reservoirs until both reservoirs have emptied sufficiently. 
         [0025]      FIG. 4  schematically shows a timing diagram of various sensor signals and state variables during the execution of the method according to the present invention. It is assumed here that reservoirs  20  and  30  have identical capacities and that, accordingly, the dispensed amounts V 1  (dispensing chamber  24 ) and V 2  (dispensing chamber  34 ) are initially equal. If different amounts V 1  and V 2  are to be dispensed, the reservoirs should be sized accordingly. The diagram shows a total of six dispensing operations, here referred to as dispensing cycles D 1  through D 6 . These dispensing cycles may occur in six successive wash cycles, but it is also possible for several dispensing cycles to take place in the course of one wash cycle. Initially, in a first dispensing cycle D 1 , equal amounts are dispensed. Both reservoirs  20  and  30  are still full enough. During the second dispensing cycle, sensor  32  detects that fill level  31  has been reached, and that no more than a residual volume  33  remains in reservoir  30 . Sensor  32  transmits a corresponding signal S 2  to controller  8 . Dispensing cycle D 2  is continued until completion, with the targeted amounts V 1  and V 2  being dispensed in the process. Since sensor  22  has not detected that fill level  21  in reservoir  20  (sensor signal S 1  remains “0”) has been reached, it is to be assumed that the volumes held in reservoirs  20  and  30  differ in terms of the ratio of their capacities. The controller processes this information such that a counter Z is incremented at the end of the dispensing cycle. This occurs always when, at the end of a dispensing cycle D, the signals of the two sensors  22  and  32  are detected to be different. This is the case at the end of the second dispensing cycle, so that counter Z is incremented from “0” to “1”. 
         [0026]    In addition, at the beginning of dispensing cycle D 3 , an adjustment is made to the amount V 1  of the first treating agent to be dispensed and/or to the amount V 2  of the second treating agent to be dispensed. In the exemplary embodiment shown, the first treating agent is dispensed in a larger amount V 1 , i.e., two metered doses are dispensed. At the end of dispensing cycle D 3 , first sensor  22  has not yet detected that fill level  21  has been reached. Accordingly, counter Z is incremented to 2. 
         [0027]    In fourth dispensing cycle D 4 , again, a larger amount V 1  of the first treating agent is added, whereas the second treating agent is added in a smaller amount V 2 . In this cycle, first sensor  22  also detects fill level  21 ; sensor signal S 1  rises to “1”. Thus, both sensors  22  and  32  signal the same condition, i.e. that the fill levels in reservoirs  20  and  30  are now both in the range of a residual volume  23  or  33 , respectively. When the signals at sensors  22  and  32  are at the same state, counter Z is to be decremented by one. Accordingly, at the end of the fourth dispensing cycle, the counter is returned to 1. 
         [0028]    In the fifth dispensing cycle, a double amount V 1  of the first treating agent is added once again because the counter is at “1”. Since the signals at the two sensors are at the same state, counter Z is returned to 0 after the fifth dispensing cycle is completed. In sixth dispensing cycle D 6 , equal amounts V 1  and V 2  are dispensed again. 
         [0029]    When residual volume  23  is reached in both reservoirs  20  and  30 , an alert is issued, informing the user that both reservoirs  20  and  30  need to be filled. It is also possible to issue a refill alert only when a reservoir  20  or  30  is actually completely empty. 
         [0030]    The adjustment of the amounts V 1  and V 2  of the first and second treating agents is preferably done only by an increase in an amount to be dispensed, and in such a way that the minimum required amount of a treating agent is always present in a wash cycle. 
         [0031]    The control method illustrated in  FIG. 4  can also be modified within the scope of the present invention. For example, instead of a switchable sensor  22  or  32 , a different sensor could be used for fill-level monitoring. Moreover, it would be possible to provide two or more sensors on a reservoir  20 ,  30  to allow for finer adjustment of the amounts to be dispensed. 
         [0032]    While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.