Patent Publication Number: US-2012031126-A1

Title: Control system for an ice maker

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/371,575, filed Aug. 6, 2010, the contents of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates to a control system for an ice maker. More particularly, the present disclosure relates a control system for an ice maker that only requires a water level sensor and a curtain sensor. 
     2. Description of Related Art 
     Conventional ice makers in market today may use a large number of sensors for determining and monitoring various factors of an ice maker. This can include, amongst other things, the use of an ice probe sensor to directly sense the ice thickness, and an air temperature sensor along with a water temperature sensor to calculate the freeze time and harvest time. 
     However the use of a large number of sensors often cannot accurately and efficiently determine these factors, such as ice capacity and the calculation of cycle times within a single ice maker. In addition, this may lead to a higher costing product having complex data collecting systems and increased component failure. 
     Thus, there is a need for an ice maker having a control system with a minimal number of sensors, resulting in a simple and low cost system. In addition, resulting in improved efficiency and providing low water waste. 
     SUMMARY 
     The present disclosure provides for a control system for an ice maker including a water level sensor and a curtain sensor for providing simple, low cost and efficient ice production. In particular, the water level sensor initiates/terminates the freeze cycle and initiates the harvest cycle and the curtain sensor terminates the harvest cycle. Furthermore, the ice maker provides for low water usage and adjustability of the ice thickness by the user. 
     The present disclosure provides a system for ice making. The system for ice making includes a controller, a compressor, a condenser, an evaporator, a water sump, a curtain disposed adjacent to the evaporator, a water distributor in communication with the water sump to draw water from the water sump and distribute the water over the evaporator during an ice making cycle, a water level sensor disposed in the water sump. The water sensor detects a high water level and signals the controller to initiate an ice making cycle, the sensor further detects a low water level in the sump and signals the controller to terminate the ice making cycle and initiates a harvest cycle. The system further includes a curtain sensor disposed about the curtain that detects when a harvest cycle has ended and sends a signal to a controller to fill the sump with water. 
     The present disclosure also provides a method for ice making. The method includes filling a water sump with water, the water having a water level, the filling moves a water level indicator toward a first position according to the water level, draining the water from the water sump after the water level indicator achieves the first position, the draining moves the water level indicator to a second position according to the water level. The method further includes filling the water sump with the water, the filling continues until the water level indicator achieves the first position. In addition, the method includes freezing the water thereby creating ice; and harvesting the ice by dropping the ice from an evaporator into a container, the container has a curtain sensor that is activated by ice impact when the ice drops from the evaporator into the container. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other and further benefits, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and: 
         FIG. 1  is a diagram of a refrigerant system 
         FIG. 2  is a front view of an ice maker of the present disclosure. 
         FIG. 3  is front view of the ice maker shown in  FIG. 1 , with a water sump removed. 
         FIG. 4  is a front view of the ice maker shown in  FIG. 1 , with the curtain removed. 
         FIG. 5  is a rear view of the icemaker shown in  FIG. 1 . 
         FIG. 6  is a rear view of the ice maker shown in  FIG. 1 , with an air condenser removed. 
         FIG. 7  is the same view shown in  FIG. 6 , with a fan motor removed. 
         FIG. 8   a  is a water level sensor of the present disclosure. 
         FIG. 8   b  is an internal circuit of the water level sensor of  FIG. 8   a.    
         FIG. 9  is flow chart illustrating a control system for an ice maker of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Referring to  FIG. 1 , a refrigeration system  11  for cooling a fluid (e.g., air or water) is shown. System  11  includes a condenser  41 , an evaporator  16 , an expansion device  45 , and a compressor  40  in fluid communication with one another. 
     Compressor  40  is operative to circulate a refrigerant between condenser  41  and evaporator  16  and to compress the vapor refrigerant before it enters condenser  41 . 
     Condenser  41 , which in the illustrated embodiment is in heat exchange relationship with outdoor ambient air, and is operative to substantially condense the vapor refrigerant. Evaporator  16 , which is in heat exchange relationship with the indoor air to be cooled, is operative to substantially evaporate the refrigerant. 
     Expansion device  45  facilitates evaporation of the refrigerant by reducing the pressure thereof before the refrigerant enters evaporator  16 . The heat absorbed by the refrigerant during evaporation cools the air passing through evaporator  16 . The cooled air is supplied to an indoor conditioned space via an air supply duct (not shown). 
     In addition to the primary components of system  11  described hereinabove, condenser  41  has a fan  46  operatively associated therewith. Fan  46  moves air (typically outdoor ambient air) across condenser  41  to cool the refrigerant in condenser  41  and facilitate condensation thereof. Similarly, evaporator  16  has a fan (not shown) operatively associated therewith for moving indoor air to be cooled across evaporator  16 . 
     Referring to  FIGS. 2-7 , there is shown an ice maker  10  according to the present disclosure. 
       FIG. 2  is a front view of an ice maker  10  having a curtain  15  with a curtain sensor  17 , a water sump  20  and a control system  25 . 
       FIG. 3  is a front view of the ice maker  10  with a water sump  15  removed from ice maker  10  to show a water pump  30  and a water level sensor  35 . 
       FIG. 4  is a front view of the ice maker  10  with the curtain  15  removed to show an evaporator  16 , a dump valve, and a water inlet valve  43 . 
       FIG. 5  is a rear view of ice maker  10  showing an air condenser  41 , a compressor  40  and water valve  43 . 
       FIG. 6  is a rear view of the ice maker  10 , with an air condenser removed to show a hot gas valve  42  and a fan motor  46 . 
       FIG. 7  illustrates the same view of ice maker  10  shown in  FIG. 6 , with fan motor  46  removed to show an expansion valve  45 . 
       FIG. 8   a  shows water level sensor  35  having a water level  36 . Water level  36  can be any type of water level, including but not limited to, a magnetic float ball. 
       FIG. 8   b  shows the internal circuit of water level sensor  35  having a first sensor position  37  (S 1 ) and a second sensor position  39  (S 2 ) to provide and receive signals with control system  25 . Water level sensor  35  can be any type of sensor, including a ring type magnet disposed within a float ball. Water level sensor  25  triggers a reed switch from on/off depending on the water level, i.e., the volume of water in water sump  20 . 
     Ice maker  10  with control system  25  is a low cost, simple system containing only  2  sensors. Ice maker  10  preferably has a water level sensor and a curtain sensor, compared to a large number of sensors contained in conventional ice makers. In addition, ice maker  10  does not require a water temperature sensor, liquid line thermistor or discharge line thermistor. Thus, ice maker  10  has a simpler design, as a result providing lower fail rates for components and a lower cost to the consumer. Ice maker  10  further provides low water usage and prevents overfill, thus is more efficient. 
     Typically, ice maker  10  has a toggle switch  5  with three positions: ICE, OFF and CLEAN. In addition, ice maker  10  may have LED lights to indicate status and/or alert issues that may arise. Furthermore, ice maker  10  may include a notification system, such as a buzzer, for indication when a fault or problem occurs. 
       FIG. 9  provides a flow chart, i.e., flow chart  900 , which illustrates operation of ice maker  10  controlled by control system  25  according to the present disclosure. 
     In particular,  FIG. 9  illustrates five (5) processes carried out by ice maker  10  under the control of control of control system  25 . The 5 processes include, but are not limited to: (i) initial water fill and purge, (ii) water fill and refrigerant start and pre-chill, (iii) freeze cycle, (iv) harvest cycle, and (v) automatic shut down sequence. 
     Initial Water Fill and Purge 
     The (i) initial water fill and purge process provides a user with a cleaner and more sanitary ice maker  10 . Flow chart  900  begins with “initial start”, when toggle switch  5  is moved to “ICE” position to activate ice maker  10 . See  FIG. 1 , Toggle Switch  5 . 
     At step  405 , control system  25  checks the status of sensor position (S 1 )  37  of water level indicator  35 . 
     If sensor position (S 1 )  37  is determined to be in the opened position, flow chart  400  progresses to step  410 . If sensor position (S 1 ) is determined to be in the closed position, flow chart  400  progresses to step  415 . 
     At step  410 , a water inlet valve (WTV) receives a signal to activate and to fill ice maker  10  with water. When ice maker  10  is filled with water, water level indicator  35  eventually keeps sensor position (S 1 )  37  in the closed position for two (2) seconds. Thereafter, the water inlet valve  43  receives a signal to deactivate and to stop the flow of water. Flow chart  400  then returns to step  405 . 
     At step  415 , ice machine  10  receives a signal to begin a dump procedure with the water pump and water dump energized while the water intake valve is de-energized. 
     Step  417  monitors sensor position (S 2 )  39  to determine if it is open or closed during the dump procedure of step  415 . If S 2  is open, flow diagram  400  is returned to step  415 . Once sensor position (S 2 )  39  is closed by water level indicator  36  flow diagram progresses to step  420 . 
     At step  420 , sensor position (S 2 )  39  is closed for two (2) seconds. Thereafter, the water pump and dump valve receive a signal to activate and to fill ice maker  10  with water. 
     Thus, ice machine  10  prepares for refrigeration and a pre-chill phase. In addition, a water pump valve, i.e., water pump valve  30  of  FIG. 2 , receives a signal to activate and to drain the water, preferably at one second intervals. 
     Water Fill and Refrigerant Start and Pre-Chill 
     As shown in  FIG. 4 , after the water purge or water dump phase described above, flow chart  400  transitions into (ii) water fill and refrigerant start and pre-chill process. The (ii) water fill and refrigerant start and pre-chill process cools down the machine first which, in turn, shortens a subsequent freeze time, thereby providing for an increased efficiency for refrigeration. 
     The transition from the (i) to (ii) occurs at step  420 . 
     At step  420 , the water inlet valve (WTV)  43  and a hot gas valve  42  are energized and the water pump and water dump valve  44  are de-energized. When flow chart  900  performs step  420 , steps  425 ,  435 , 440 ,  445  and  450  are run. While these steps are performed, steps  430  is run in parallel with step  433  performed after step  433  is performed. All of these steps are discussed below. 
     At step  420 , the hot gas valve (HGV) and the water inlet valve (WTV) receive a signal to activate at one second intervals. 
     Step  425  provides a wait period of  45  seconds for refrigerant system balance. After  45  seconds elapses, flow chart  400  progresses to step  435 . 
     At step  435 , a contactor, located in control box  25 , receives a signal to activate, and for refrigeration to begin. After step  435 , flow chart  400  progresses to step  440 . 
     Step  440  provides a wait period for 5 seconds for refrigerant system hot balance. After the wait period of 5 seconds, flow chart  400  progresses to step  445 . 
     At step  445 , the HGV is de-energized. That is, the hot gas valve receives a signal to deactivate and to shut down. This causes ice machine  10  to enter into a pre-chill phase. After step  445 , flow chart  400  progresses to step  450 . 
     Step  450  provides a 30 second wait period is provided to cool and pre-chill the ice maker  10 , before entering the (iii) freeze cycle process described below. 
     During performance of steps  425 ,  435 , 440 ,  445  and  450 , flow diagram  900  also evaluates if the water inlet valve is de-energized in step  433 . In particular, when the water level in ice maker  10  increases to keep sensor position (S 1 )  37  closed for 2 seconds, the water inlet valve receives a signal to deactivate and to stop the flow of water into ice maker  10 . Thereafter, flow diagram  900  progresses to step  450  to determine if the pre-chill phase continues for at least 30 seconds. If step  450  is valid, i.e., Y, the water pump is activated and ice machine  10  receives a signal to enter into a freeze cycle. 
     Freeze Cycle 
     During the (iii) freeze cycle, illustrated in steps  455  and  460 , ice formation increases as the water level reduces to keep second sensor position (S 2 )  39  open. The water level reduces as water becomes ice in the water trough. After 2 seconds, ice machine  10  remains in the freeze cycle for 2 minutes. Thereafter, at 2 seconds from the end point of the freeze cycle, a controller in control system  25 , reads a freeze time adjustment setting and, based on this setting, the controller signals ice machine  10  to either extend or shorten the 2 minute freeze cycle. Furthermore, the 2 minute timing of the freezing cycle is adjustable for preferred ice thickness of a user. Thereafter, ice machine  10  enters the (iv) harvest cycle starting at step  465  described-below. 
     Harvest Cycle 
     At step  465 , ice machine  10  enters the harvest cycle. At step  465 , the HGV, water pump valve and water dump valve become energized or activated. That is, the HGV, water pump valve, and the water dump valve receive a signal to activate and to harvest the ice and drain the water. 
     Preferably, the HGV, water pump valve and the water dump valve harvest the ice and drain the water at one second intervals, i.e., step  470 . 
     At step  475 , after harvesting the ice in step  470 , the water pump and the water dump valves receive a signal to deactivate and to shut down, while the water inlet valve receives a signal to activate and to fill ice maker  10  with water in preparation for the next freeze cycle. Draining and re-filling the water during the harvest cycle provides for a cleaner and more sanitary ice maker  10 . 
     Next, in step  480 , the formed ice drops from the evaporator  16  and engages curtain sensor  17 . During this step, ice machine  10  receives a signal to end the harvest cycle and deactive the hot gas valve. Then, ice machine  10  enters a pre-chill phase for the next freeze cycle. 
     In step  485 , ice full, ice maker  10  initiates another pre-chill phase. In particular, when the ice is harvested, it is pushed out onto water curtain  15 , which opens curtain sensor  17 . If curtain sensor  17  is opened and then and closes before  7  seconds have elapsed, a signal is sent to initiate another pre-chill phase. If curtain sensor  17  remains opened for more than  7  seconds, then the controller receives a signal to initiate an automatic shut down. If ice machine  10  enters a harvest cycle with curtain sensor  17  open, the harvesting occurs for a maximum of 3.5 minutes. 
     Automatic Shut Down Sequence 
     In parallel to the harvest cycle, discussed above, steps  480  and  485  also perform an automatic shut down sequence. 
     Once curtain sensor  17  is opened for more than  7  seconds during a harvest cycle, ice machine  10  receives a signal to go into automatic shutdown. Ice machine  10  receives a signal to restart the initial water fill and purge and/or prechill once curtain sensor  17  closes again. 
     However, ice machine  10  remains off for at least 3 minutes before it can automatically restart, the 3 minutes begin at the time of automatic shutdown. Ice machine  10  can restart after the at least 3 minutes has elapsed and curtain sensor  17  recloses. If curtain sensor  17  closes prior to the at least  3  minutes has elapsed, ice machine  10  restarts as soon as the 3 minutes have elapsed. Ice machine  10  restarts by following the initial start-up sequence.