Abstract:
An apparatus reminds an operator of a need to change water in a reservoir of a warewasher. A counter that counts operating cycles of the warewasher and a sensor provides signal indicating that the reservoir has been drained and refilled. A controller responds to the counter having a first threshold value by activating an annunciator to alert the operator that is it time to change the water. Thereafter when the counter has a greater second threshold value and the controller disables operation of the warewasher until the sensor indicates that the reservoir has been drained and refilled. Thus the operator is required to change the water in order to continue using the warewasher.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to automatic warewashers for kitchenware; and in particular to electronic control circuits for automatically operating the warewasher. 
     2. Description of the Related Art 
     Commercial kitchens have equipment to clean and sanitize glassware, dishes, silverware, pot, pans and cooking utensils, which are collectively referred to as “kitchenware.” Such equipment, commonly known as a “dishwasher” or more generically as a “warewasher”, has a cabinet defining an internal chamber into which trays of kitchenware are placed for washing. A washing and rinsing assembly within the chamber has a plurality of nozzles from which water sprays onto the kitchenware being cleansed. The lower part of the cabinet forms a reservoir that collects the water which is repeatedly circulated through the nozzles by a pump during the wash cycle. Then, fresh water from an external supply line is fed through the nozzles during a rinse cycle. When the rinse water flows into the reservoir, some of the reservoir water overflows into a drain thus replacing some of the water from the wash cycle. 
     Because the water is not completely drained from the reservoir for each wash cycle, food particles, grease and other debris from the kitchenware accumulates in the reservoir. As a result a human operator periodically (e.g. every two hours of operation) must manually drain and refill the warewasher to remove the accumulated debris and provide fresh water. Operators often forget to change the water or lose track of how long the time interval has been since the previous water change. 
     To solve this problem, various systems have been developed to remind the operator when to change the water. One such system, counted the number of wash cycles and upon the occurrence of a given number of cycles, provided a visual or audible warning to the operator indicating the need to change the wash water. For example, a lamp on a control panel illuminated and a buzzer sounded to provide that indication. However, operators often ignored this warning, pressed a reset switch and continued to wash dishes without changing the water in the warewasher. Failure to periodically drain and refill the machine with fresh water allows debris to accumulate to unsatisfactory levels which adversely affects proper cleaning of the kitchenware. 
     Therefore, there still exists a need for a control system that requires operators occasionally drain and refill the water in a warewashing machine. 
     SUMMARY OF THE INVENTION 
     A method for controlling operation of a warewasher detects a condition that requires corrective action. Examples of such conditions include the need to change the water in the warewasher, the water having too low a temperature for satisfactory cleaning, or exhaustion of detergent or another chemical in an automatic dispenser. Upon the occurrence of the condition the human operator is alerted of the need to take the corrective action. Thereafter, an operational parameter of the warewasher is monitored to provide an indication when the corrective action is taken. If the corrective action does not occur, subsequent operation of the warewasher is disabled. When the monitoring indicates occurrence of the corrective action, operation of the warewasher is enabled. 
     One version of this method is adapted to indicate when water in a reservoir of the warewasher needs to be drained and refilled. This process involves counting operations of the warewasher to produce a count and sensing at least one characteristic of the warewasher that indicates draining and refilling the reservoir. That characteristic may be the water level in the reservoir or electrical conductivity within the reservoir, for example. In response to the count having a predefined value, further operation of the warewasher is suspended until the sensing indicates that the reservoir has been drained and refilled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric illustration of a commercial warewasher which incorporates the present invention; 
         FIG. 2  is a schematic representation of control circuit for the warewasher; 
         FIG. 3  is a flowchart of a software routine that is executed by the control circuit to remind the operator to change the water in the warewasher; 
         FIG. 4  is a flowchart of a software routine that suspends washing when the temperature of water within the warewasher decreases below a threshold level; and 
         FIG. 5  is a schematic representation of an operator reminder system that is retrofitted on an existing warewasher. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference to  FIG. 1 , a commercial kitchen warewasher  10  has a cabinet  12  defining a chamber into which kitchenware is placed for washing. Two side doors  13  and  14  are slidably mounted on the cabinet  12  to close openings through which racks of glasses and dishes pass into and out of the chamber. The side doors  13  and  14  are connected to a link arm  17  so that they operate in unison. A front door  19  allows access to the interior of the chamber maintenance. The cabinet  12  contains standard washing and rinsing assembly that includes a plurality of nozzles  16  that spray water supplied by a wash pump  18 . A region at the bottom of the cabinet  12  forms a reservoir  15  into which the water drains from the kitchenware and which holds a volume of water between washing operations. An overflow drain in the reservoir prevents the water from rising above a given level. 
     Referring to  FIG. 2 , the warewasher  10  has a standard control system  30  that employs an electronic controller  22 . The controller  22  is based on a microcomputer  24  which executes a program that is stored in memory  26  and defines the operation of the warewasher. The controller  22  includes input circuits  28  that receive signals from various devices on the warewasher  10 , as will be described. Input signals also are received from the operator control panel  20  that has switches by which the human operator starts a cleaning operation and selects operational functions to be performed. The control panel  20  also has devices that provide visual indications of the functional status of the warewasher. A modem  36  is connected to the microcomputer  24  for the exchange of data with other control systems and computers via a computer network  38 . 
     The controller  22  has several output drivers  32 , one of which activates an annunciator  34 , such as a buzzer or beeper to produce an audible warning or a lamp to provide a visible alert. Another output driver  32  operates a solenoid water valve  40  during the rinse cycle to send fresh water through the nozzles  16 . A manually operated supply valve  42  is provided to fill the reservoir  15  at the bottom of the cabinet  12  prior to operating the warewasher  10 . A drain valve  44  is manually operated to drain water from the reservoir  15  into the waste water system of the building. Another output of the controller  22  activates the wash pump  46  during the wash cycle. The controller  22  also automatically governs dispensing detergent and additives into the warewasher cabinet  12 . Specifically, the microcomputer  24  determines when to activate a detergent pump  48 (see  FIG. 1 ) in response to a signal from a conductivity sensor  49 , that is located below the water line of the reservoir  15 . Additional containers  51  and  52  are provided to store a rinse additive and a sanitizer chemical, respectively. Other output drivers  32  operate pumps  54  and  56  to introduce the rinse additive and a sanitizer chemical into the warewasher cabinet  12  at appropriate times during the cleaning cycle. 
     A water temperature (WT) sensor  58  is located in the reservoir  15  to produce a signal indicating the temperature of the water. The controller  22  responds to that temperature signal by activating a water heater  60  that has a heating element within the reservoir. Another temperature sensor  62  is mounted in a conduit that carries water during the rinse cycle and thus provides an indication of the rinse water temperature (RT) to ensure that the proper water temperature is being maintained. A pair of sensor switches (SD, FD)  63  and  64  provide signals indicating when either the side doors  14  or the front door  19  is open and the controller  22  suspends operation in those cases. A set of three sensors  65 ,  66  and  67  respectively detect when the detergent, rinse additive and sanitizer containers  50 ,  51  and  52  are empty 
     The control system  30  operates the warewasher to perform a conventional cleaning cycle which is commenced when the human operator presses the start button  68  on the control panel  20 . The action also causes the microcomputer  24  to execute a software routine  70  that maintains a count of the wash cycles to monitor water quality in the warewasher  10 . That routine  70  is depicted by the flowchart in  FIG. 3  and begins at step  71  where the signal from the conductivity sensor  49  is read and then inspected at step  72  to determine if the conductivity is zero as occurs when the reservoir  15  is empty. For example, this condition exists when the operator has drained the reservoir in response to a previous alarm indication to do so, as will be described. When the conductivity is zero, a count of wash cycles previously stored in the memory  26  is reset to zero, at step  73  and the water quality routine  70  returns to step  71 . The processing continues to loop through steps  71 - 73  until a non-zero conductivity measurement is received from the sensor  49  as occurs when the reservoir  15  contains water. 
     Then at step  74  the microcomputer  24  checks an input that indicates whether the start button  68  on the control panel  20  has been pressed by the human operator. If not, execution of the water quality routine loops back to step  71 . When the operator presses the start button  68 , the execution advances to step  75  at which the count of the wash cycles stored in the memory  26  is incremented. The new count is compared at step  76  to a first value that corresponds to 90% of a threshold second value X. That threshold second value is the maximum number of wash cycles that are permitted for each fill of the wash water reservoir  15 . When the wash cycle count reaches 90% of that threshold, the water quality routine  70  branches to step  77  at which the microcomputer  24  activates the annunciator  34  which begins beeping to alert the human operator that it is time to change the wash water. In addition an indicator lamp on the control panel  20  also in illuminated to provide a visual alert. A message of the alarm condition also may be sent via the modem  36  to a designated device address on the computer network  38 . 
     After the annunciator  34  has been activated, the warewasher continues to increment the wash cycle count and function normally, until at step  78  the wash cycle count is determined to have reached the threshold second value X. Upon that occurrence, the microcomputer  24  disables the normal operation of the warewasher  10  at step  79 . Specifically, the controller  22  closes the rinse water valve  40 , de-energizes all the pumps  46 ,  48 ,  54  and  56  and turns off the heater  60 . Usually the operation will be suspended at the start of a new cleaning cycle as that is when the water quality routine  70  detects the wash cycle count threshold X being exceeded. 
     The microcomputer  24  then begins executing a section of the water quality routine  70  which determines when the human operator has drained and refilled the reservoir  15  with fresh water. At step  80 , the signal from the conductivity sensor  49  is read and then inspected at step  82  to determine if the conductivity is zero as occurs when the reservoir  15  is empty. When that happens, the water quality routine  70  sets a drain flag at step  84  that indicates that event and then return is to step  80  to monitor the conductivity sensor  49 . 
     The water quality routine execution continues to loop through steps  80 - 84  until the reservoir  15  is refilled with water at which time the conductivity rises above zero. Upon that occurrence, a determination is made at step  86  whether the drain flag is currently set as occurs when the reservoir  15  has been drained and refilled. If that is not the case the water quality routine  70  loops back to monitor the conductivity sensor  49 . When the drain flag is found to be set at step  86 , the water quality routine branches to step  88  at which the microcomputer  24  resets the drain flag and turns off the annunciator  34  and other devices that indicate the alarm condition. Thereafter, the water quality routine ends returning to the main washing control program at a point where a new wash cycle commences. 
     In addition to the water becoming dirty and occasionally needing to be changed, the temperature of the water within the reservoir must be monitored to ensure that it is above a level at which proper cleansing of the table and kitchen ware will occur. Normally this is not a problem as the water heater element  60  maintains the water in the reservoir at a satisfactory temperature. However, if the warewasher is operated very frequently and the temperature of the hot water added during the rinse cycles is relatively low, the water temperature in the reservoir may decrease below a desirable level. To provide a safeguard against prolonged operation of the warewasher  10  with an insufficient water temperature, the microcomputer  24  also executes a water temperature routine  90  depicted by the flow chart in  FIG. 4 . 
     This routine commences at step  91  with the microcomputer  24  reading the output signal from the water temperature sensor  58  within the reservoir  15 . Then at step  92 , a determination is made whether that temperature is above a threshold value designated Y at which satisfactory cleaning can occur. If the temperature is satisfactory, the program execution branches to step  93  where a temperature alarm, that might have been activated previously, is reset and a was cycle count is set to zero before advancing to step  98  to start a new wash cycle. 
     If the temperature is found to be an unsatisfactorily low at step  92 , the control process branches to step  94  at which a low temperature alarm is activated to warn the human operator of that condition. Operation of the warewasher does not terminate at this time, but is allowed to continue for a limited number of additional wash operations. If those operations are spaced sufficiently apart in time, the reservoir water heater  60  may be able to raise the water temperature to a desirable level. 
     Therefore, at step  95  a wash cycle count which is separate from the similar count utilized by the water quality routine  70 , is incremented with its value stored in another location of memory  26 . At step  96 , a determination is made whether this wash cycle count is equal to or exceeds a value at which further operation of the warewasher should be suspended until the water temperature increases to a satisfactory level. Until that number of cycles occurs during a unsatisfactory water temperature condition, the program branches to step  98  and returns to the main control program to commence a new wash cycle. If the warewasher  10  continues to operate with an unsatisfactory water temperature and the wash cycle count reaches the threshold value Z at step  96 , the program execution branches back to step  91  without allowing a wash cycle to commence. Thereafter, as long as the reservoir water temperature is below the desired temperature Y, the water temperature routine  90  continues to loop without allowing a wash cycle to occur. At some time thereafter, the reservoir water heater  60  will have increased the temperature to that temperature threshold Y and the program execution will branch from step  92  through steps  93  and  98  enabling wash cycles to occur. 
     Just as human operators have previously ignored alarm signals to change the water in the reservoir  15 , they also have ignored alarms relating to other consumables used in the washing process. As used herein, the consumables include water, detergent, rinse additives, and the sanitizer. As noted previously, sensors  65 ,  66  and  67  respectively detect when the containers  50 ,  51  and  52 , which hold the detergent, rinse additive and sanitizer, become empty. When anyone of these consumables is not available for automatic dispensing into the warewasher, the microcomputer detects that based on the sensor signals. The microcomputer responds by suspending further operation of the machine until the respective container is filled with a new quantity of that consumable. At that time, the sensor signal will indicate the replenishing of that consumable and the microcomputer will once again enable operation of the warewasher. 
     Referring to  FIG. 5 , a version of the reminder system  130  can be retrofitted on an existing the warewasher  100  that has an electromechanical controller  102 . That type of controller  102  employs a timer  104  in which an electric motor  106  drives a cam assembly  108 . The cam assembly  108  includes a plurality of lobes which selectively open and close a like plurality of switches that apply power to different components within the warewasher. The speed of the motor and the shape of the cam lobes determine the sequence and periods that the components are activated during an operating cycle that includes sub-cycles for washing, sanitizing, and rinsing. 
     A momentary start switch  110  applies power from a power line connection  112  to the motor  106  and to the coil of a main relay  114 . This causes the timer  104  to advance and close a switch that applies power from the main relay  114  to a conductor  116  thereby sustaining operation of the timer motor  106  and maintaining the main relay closed. This switch within the timer  104  opens at the end of the operating cycle, thereby stopping the warewasher until the start switch  110  is pressed again. Another switch within the timer  104  is connected via terminal A to a solenoid valve  118  which controls flow of water to the warewasher during the rinse sub-cycle. Still another switch of the cam assembly  108  is coupled via terminal B to a wash pump  120  which circulates water through spray arms and nozzles in the warewasher cabinet. The timer switches connected to terminals C, D, and E respectively control pumps  121 ,  122 , and  123  which dispense a detergent, a rinse additive, and a sanitizer chemical at selected times during the operating cycle. 
     A reminder system  130  according to the present invention is added to the electromechanical controller  102  of the warewasher  100 . The reminder system  130  has a microcontroller  132  in which a microcomputer, memory and input/output circuits are combined into a single integrated circuit. The microcontroller  132  has an input  134  connected to the controller conductor  116  that goes from zero volts to the line voltage when the human operator presses the start switch  110  to commence a washing cycle. Thus the microcontroller  132  counts each time that voltage makes a rising transition to keep a count of the wash cycles. 
     The microcontroller  132  executes a software program that is similar to the water quality routine  70  in  FIG. 3 . Therefore, when the wash cycle count reaches 90% of the threshold value, an annunciator  135  is activated to alert the human operator that it is time to change the water. If the operator continues to use the warewasher without changing the water and the count reaches the threshold value, the microcontroller  132  activates a termination relay  136  that opens a switch which disconnects the warewasher controller  102  from the electricity supply. Thus, the operation of the warewasher is suspended. 
     A water level sensor switch  138  is placed within the reservoir of the warewasher and is connected to an input of the microcontroller  132 . That sensor switch  138  is closed when the reservoir is empty. Therefore, after the annunciator  135  is activated, the microcontroller  132  monitors the input signal from the water level sensor switch  138 . That signal goes low which occurs when the water is drained from the reservoir and then goes high indicating the reservoir has been refilled. That signal sequence causes the microcontroller  132  to de-energize the termination relay  136  which reapplies electricity to the controller  102 , thereby restoring operation of the warewasher. 
     The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.