Abstract:
In a chiller, an apparatus and method for automatically identifying a temperature probe for use in a chilling operation is provided in order to reduce user error. In the place of manual selection by a user, automatic selection of the appropriate temperature probe is accomplished by comparing the temperature of the given temperature probe to a threshold temperature. An additional apparatus and method for filtering a displayed compartment temperature is provided to reduce user confusion. The responsiveness of the displayed temperature to temperature changes in the compartment is reduced when the compartment door is opened.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to commercial food chilling equipment and, more particularly, to chillers having features for minimizing the potential for user error and confusion during the set-up and monitoring of a chilling operation. 
     BACKGROUND OF THE INVENTION 
     Commercial food product chillers, commonly referred to as blast chillers, are typically used to chill hot food products to a safe temperature for storage. For example, a hot food product at 145° F. to 160° F. or more may be taken just out of the oven, placed in the chiller, and rapidly cooled to a low temperature of 40° F. or less. Such rapid chilling of the food product is desirable for a variety of reasons, including food safety. 
     Known food product chillers generally operate in one of two modes, namely a chill by temperature mode or a chill by time mode. In the chill by temperature mode a temperature probe is placed in the food product and the desired chilled temperature of the food product can be entered into the machine by a user. The chilling operation then runs until the temperature probe indicates that the food product has reached the desired chilled temperature. In the chill by time mode, a user simply enters a time period for chilling the food product and the chilling operation then runs for the entered time period. In either type of chilling operation a user may also set the type of chill (hard or soft), and/or a desired air temperature within the chilling compartment. Some chillers are also configured to operate in a freeze mode for freezing food products. As used herein the term “chiller” broadly encompasses both units which include a freeze mode and units which do not include a freeze mode. 
     One opportunity for user error with known chillers occurs during the initialization of a chill by temperature operation when the user must select one of several temperature probes to monitor the cooling cycle of a hot food product. When this step is performed properly, the user will insert a given temperature probe into a hot food product and identify the inserted probe for use in the chilling operation through a user input device. For this purpose the probes are typically numbered. The identified temperature probe will then monitor the temperature of the food product as it is cooled. Occasionally, however, the user will accidentally identify a different temperature probe than the one placed into the hot food product causing the cooling cycle of the food product to run improperly. When this error occurs it may also be necessary to discard the food product. Consequently, it would be desirable to provide a method for automatically identifying for use a temperature probe that has been placed into a hot food product, thereby eliminating the potential for user error. 
     Another opportunity for user confusion occurs during the loading and unloading of food products through a chiller door. Because opening of the chiller door can cause rapid temperature increases in the cooling compartment, users who monitor the cooling compartment temperature through a temperature display may become concerned that the chilling operation has been interrupted. When this confusion occurs users will occasionally discard food products as waste thinking them unsafe. A similar problem can occur in other types of cooling apparatus such as refrigerators having temperature displays. Accordingly, it would be desirable to provide a method for filtering the temperature that is displayed to the user in a manner such that the responsiveness of the display to rapid temperature changes in the cooling compartment is reduced when the door is opened, thereby eliminating the potential for user confusion. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the present invention, a chiller apparatus is provided including a chilling compartment, a chilling system for chilling the chilling compartment, and a plurality of temperature probes for monitoring the temperatures of food products during chilling operations. A controller is coupled to the temperature probes for receiving signals therefrom and is capable of determining whether to identify a given temperature probe for use in a chilling operation based, at least in part, on a signal received from the given temperature probe. 
     In a second aspect of the invention, in a chiller including a chilling compartment having a plurality of temperature probes associated therewith, a method for automatically determining whether a given temperature probe has been selected for use in a chilling operation is provided. The method involves comparing a temperature of the given temperature probe to a threshold temperature; and determining whether the given temperature probe has been selected for use in the chilling operation based at least in part upon the comparison. In one embodiment the determination is made in order to automatically identify the given probe for use in the chilling operation if a user selected the given probe by placing it in a hot food product. In another embodiment, the given probe may be examined based upon user identification of the given probe via a user input device, wherein the determination is made in order to verify that the user identification of the given probe was correct. 
     In a third aspect of the invention, a method for displaying an air temperature of a cooling compartment involves altering the responsiveness of the temperature that is displayed to temperature changes according to the status of the cooling compartment door as being open or closed. When the door is closed the temperature that is displayed is most responsive to temperature changes in the cooling compartment. When the door is open the responsiveness of the temperature display to temperature changes is decreased in order to reduce the likelihood of user confusion. 
     In the fourth aspect of the present invention, a cooling apparatus is provided including a cooling compartment, a cooling system for cooling the cooling compartment, and a door which can be opened to load or unload food products from the cooling compartment. An air temperature sensor is used to obtain an air temperature of the cooling compartment and a display device is used to display the air temperature to the user. A controller is coupled to the air temperature sensor and the display device for displaying a temperature based, at least in part, on a signal received from the air temperature sensor. The controller is also coupled to a door state sensor and is operable at least once during an open state of the door to reduce the responsiveness of the display temperature to temperature changes in the cooling compartment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic depiction of one embodiment of a chiller; 
     FIG. 2 is a wiring schematic of the chiller of FIG. 1; 
     FIG. 3 is a flowchart depicting one embodiment of an automatic probe detection algorithm; and 
     FIG. 4 is a flowchart depicting one embodiment of a temperature filtering algorithm. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to drawing FIG. 1, a schematic depiction of a chiller  10  according to one embodiment of the present invention is shown. The chiller  10  includes a chilling compartment  12  which may include multiple racks or shelves (not shown) for receiving food products to be chilled, the compartment typically defined by an insulated housing having an associated door  13  movable between open and closed positions. A plurality of temperature probes  14  are positionable in the chilling compartment  12  for insertion into food products placed in the chilling compartment  12 . The probes  14  may be connected to a common wiring harness  16  which extends to a controller  18 . The probes  14  output temperature indicative signals to the controller  18 . An air temperature sensor  20  is also provided for sensing the temperature of air in the chilling compartment  12  and producing a temperature indicative signal which is delivered to the controller  18 . A chilling system  22 , operated by the controller  18 , generates chilled air which is delivered to the chilling compartment  12  during chilling operations. The chilled air may be circulated through the chilling compartment and back to the chilling system using one or more fans or blowers (see FIG.  2 ). 
     The controller  18  is also connected to a display device  24 , such as an LCD screen or VF display, for effecting display of information to a user. A user input device  26  is provided for allowing a user to input information to the controller  18 . In one embodiment the user input device  26  may be a series of input keys or buttons along the sides of the display device  24  which allow a user to initiate actions or enter information according to information displayed on a portion of the display device  24  alongside the keys. Other user input devices could be used. For example, the user input device could be combined with the display device in the form of a touch screen display, or an alphanumeric data entry key array could be provided. 
     The chiller includes a label printing mechanism  28  having an associated supply of adhesive label stock. The controller  18  is connected for effecting printing of labels by the printing mechanism  28 . A ticket printing mechanism  30  having an associated supply of non-label print stock is also provided, with the controller  18  connected to effect printing of tickets by the printing mechanism  30 . In one embodiment, the printing mechanisms may be formed by thermal print heads. 
     Referring now to FIG. 2, a schematic diagram of chiller wiring is shown. The controller  18  may include an RS- 232  communications interface  32 , a programming interface  34 , and an expansion interface  36 . The programming interface  34  may be used to reprogram the controller  18 . In the illustrated embodiment the controller  18  is connected directly to certain components and indirectly, through input/output board  38 , to others. The controller is directly connected to each of the temperature probes  14 , the air temperature sensor  20 , the user input device  26 , the display device  24 , and the printing mechanisms  28  and  30 . The controller is also directly connected to an evaporator coil temperature sensor  40  which may be used in defrost operations of the coil. 
     The controller  18  is connected through input/output board  38  to fans  42 ,  44  and  46  for controlling the flow of chilling air through the chilling compartment. The controller  18  is connected through input/output board  38  to the coil portion  48  of the coil heater relay CH which effects contactor portion  50 . The controller  18  is also connected through the input/output board  38  to solenoid  52  which is connected in line with the chilling system  22  to control the flow of the refrigerant fluid. Because operation of the compressor motor  54  and fan  56  of the chilling system  22  is responsive to high and low pressure switches  58  and  60 , the chilling system can be controlled via control of the solenoid  52 . Left and right heater elements  62  and  64  are provided for defrosting. 
     A front door switch  66  and fan door switch  68  are also connected through input/output board  38  to controller  18  and properly positioned for providing signals indicative of the open/closed state of each of the chilling compartment door  13  and fan compartment door (not shown). Contact, magnetic, optical or other suitable switches could be used. The controller  18  can also effect operation of an alarm  70 , such as a beeper, light or other annunciator, through the input/output board  38 . Power supplies  72  and  74  are also shown. 
     Referring now to FIG. 3, one embodiment of an automatic probe detection method is shown and is identified as an Activate Probes routine. The operations of the method may be performed by the controller  18  which includes associated memory (EEPROM, RAM, ROM and/or other memory) for storing operating code and other information. The data that are used to carry out the operations of the method are supplied to the controller  18  by the plurality of temperature probes  14 , the air temperature sensor  20 , and the user input device  26 . The method may be started when a user, via the user input device  26 , requests a chill by temperature operation after at least one of a plurality of temperature probes  14  is inserted into a hot food product. Of course in other embodiments the method could be performed continuously in which case the temperature probe  14  could be inserted into a food product at any time in relation to the start of the method. 
     The Activate Probes routine is initiated at step  80 . A number of variables are then initialized in step  82 . The variables include: a count variable (n) that identifies which temperature probe is currently under consideration for use; a status variable (ACTIVE) that indicates whether one or more probes are active—initialized to false; and a temperature variable (delta) is set to a given value. In the embodiment pictured in FIG. 3, the temperature variable (delta) is a stored parameter that cannot be altered by the user. In other embodiments, however, the temperature variable (delta) could be variable by the user by means of the user input device  26  or could be varied automatically. 
     No matter how delta is set, in the illustrated embodiment it is then added to some measured temperature in step  82  to calculate a threshold temperature. The threshold temperature may be calculated by adding the temperature variable (delta) to a measured air temperature in the chilling compartment as determined by the air temperature sensor  20 . In other embodiments however, a unique threshold temperature could be calculated for each temperature probe by adding the temperature variable (delta) to a prior measured temperature of each temperature probe that had been stored in memory by the controller  18 . In some applications the threshold temperature may simply be a predetermined constant stored in memory. 
     Starting with the first temperature probe and proceeding sequentially through each of the temperature probes, a series of operations is used to determine whether to identify each probe for use in a chilling operation. When the operations are completed on any given probe the counter variable (n) is increased and the next probe sequentially is considered. In the embodiment shown in FIG. 3, each temperature probe will be considered in turn only once. Therefore, at least one temperature probe  14  should be inserted into a hot food product before the method is started in step  80  in order for a temperature probe to be identified for use. In other embodiments, however, the steps could repeat for a certain time period to give a user a chance to insert a probe. 
     In step  84 , the disabled status of the temperature probe currently under consideration is tested. A probe may be disabled because it is not functioning properly. If it is determined that the probe currently under consideration is disabled, then the counter variable is increased and the next temperature probe is considered. If it is determined that the probe currently under consideration is not disabled, then the idle status of the probe is tested in step  86 . 
     A temperature probe that is currently in use in a chilling operation is not idle and therefore not available for identification for use in another chilling operation. If the status of the probe is determined not to be idle then the counter variable (n) is increased at step  92  and the next temperature probe is considered. If the status of the probe currently under consideration is determined to be idle, then the temperature of the probe is compared, in step  88 , to the threshold temperature. 
     A primary assumption of the embodiment shown in FIG. 3 is that the temperature of a probe that is not in a food product will be close to the air temperature of the chilling compartment since the probes are stored in the chilling compartment when not in use. Therefore, if the temperature of a probe is greater than the air temperature of the chilling compartment plus the temperature variable (delta), that is greater than some threshold temperature, then a conclusion is made that the probe has been inserted into a hot food product. Consequently, in step  88  the temperature of the probe currently under consideration is compared to the threshold temperature to determine whether to identify the probe for use in a chilling operation. If the temperature of the probe does not exceed the threshold temperature then the counter variable (n) is increased in step  92  and the next temperature probe is considered. If the temperature of the probe currently under consideration does exceed the threshold temperature then the probe under consideration is set to active and the status variable (ACTIVE) is changed from false to true in step  90 . A probe status table may be maintained in memory for identifying active probes, and the probe may be set to active by flipping a bit in the table. Once set to active, the probe has been identified for use in a subsequent chilling operation. Even after a probe is identified for use in a chilling operation the counter variable (n) is increased in step  92  and the next temperature probe is considered in case the user has elected to use more than one probe. 
     In the embodiment shown in FIG. 3 only three temperature probes are envisioned for use although clearly more could be used. In step  94  a determination is made as to whether all of the temperature probes have been considered by comparing the counter variable (n) to the specified number of probes ( 3  in this case). If the counter variable is less than the specified number of probes then the automatic probe detection algorithm is not completed and step  84  will be repeated. If the counter variable is not less than the specified number of probes then all probes have been checked and the state of the status variable (ACTIVE) is returned. If ACTIVE has been set to true, the controller  18  examines the probe status table to determine which probe or probes to use in the chilling operation, and may also display via the display device  24  which probes will be used. If ACTIVE is still false, then no probe has been identified and the controller  18  may query the user via the display device  24  to manually insert and identify a probe. 
     Where a user does manually identify which probe to use in a chilling operation, the controller  18  may verify whether the user&#39;s identification is correct. For example, if a user manually identifies a given probe for use the controller  18  may monitor that probe for a period of time to determine if that probe has in fact been placed in a hot food product. Such monitoring would similarly be achieved by evaluating whether the temperature of the given probe rises above a threshold temperature. If a determination is made that the manually identified probe was in fact placed in a hot food product the chilling operation may proceed as normal. On the other hand, if temperature of the manually identified probe does not rise above the threshold temperature the controller determines that the user accidentally identified the incorrect probe and may prompt the user via the display device or an alarm to verify and/or correct the probe identification. 
     Referring now to FIG. 4, one embodiment of a temperature filtering method is shown. The steps of the method may be performed by the controller  18  which includes associated memory (EEPROM, RAM, ROM and/or other memory) for storing operation code and other information. The data that are used to carry out the operations of the algorithm are supplied to the controller  18  by the air temperature sensor  20  and the front door switch  66 . Although at least four distinct filtering methods are contemplated, only one such method is shown in FIG.  4 . In each method, including the one shown in FIG. 4, adjustments to the filtering operation are initiated when the chilling compartment door  13  is opened as determined by the front door switch  66 . 
     The illustrated embodiment of the present invention that is shown in FIG. 4 utilizes a continuously repeating algorithm that begins in step  110  with the initialization of variables. These variables include an adjustment variable (Adjust) which is set to zero. After initialization of the variables in step  110 , in step  112  a determination is made as to whether it is time to consider adjusting the filtering procedure. This determination can be made, for example, by measuring absolute time, i.e., every 5 seconds, or by counting the number of complete passes through the algorithm, i.e., every 10 passes. 
     If, after the determination in step  112 , it is not time to consider adjusting the filtering procedure, then a Sum value is adjusted in step  118  by subtracting the value of the average temperature (AVG) that was calculated in step  120  on the previous pass through the filtering algorithm, adding the current measured temperature (New), and adding the current value of the adjustment variable (Adjust). Using this calculated Sum value a new average is then calculated in step  120  by dividing the Sum value by 2 n , wherein 2 n  represents the size of the averaging window. After the new average temperature is calculated in step  120 , the calculated value is displayed to the user in step  122  by means of the display device  24 , which is coupled to the controller  18 , and the algorithm is then repeated. 
     If, after the determination in step  112 , it is time to consider adjusting the filtering procedure, then the open status of the chilling compartment door  13  is tested in step  114  by means of the front door switch  66 . If the door is open then the current value of variable n is compared in step  128  to a maximum variable value. If the current value of the variable n is less than the maximum variable value then the value of adjustment variable (Adjust) is calculated in step  130  by multiplying the average temperature (AVG) that was calculated in step  120  on the previous pass through the filtering algorithm by 2 n . The value of the variable n is then increased in step  132  before calculating a new Sum and average in steps  118  and  120  respectively. After the new average temperature is calculated in step  120 , the calculated value is displayed to the user in step  122  by means of the display device  24  and the filtering method is then repeated. By increasing (n) at step  132  and increasing Sum by a non-zero Adjust value which is a factor of the previous average, the size of the averaging window is doubled making the displayed temperature less responsive to changes in temperature within the chilling compartment. In this method it is possible for the size of the averaging window to be increased more than once. It is also possible that the averaging window will not be increased at all if the door  13  is only open for a few seconds. 
     Referring again to step  128 , if the value of the variable n is not less than the maximum variable value, then steps  118 ,  120  and  122  are performed with no change to n and with Adjust=0. 
     Referring again to step  114 , if the status of the chilling compartment door  13  is determined not to be open, then the value of the variable (n) is compared in step  116  to a minimum variable value. If the value of the variable (n) is greater than the minimum variable value, then the value of the variable (n) is decreased in step  124  and the adjustment variable (Adjust) is calculated in step  126  by multiplying the average temperature that was calculated in step  120  on the previous pass through the filtering algorithm by 2 n , and taking the negative of that product. A new sum and average are then calculated in steps  118  and  120  respectively. After an average temperature is calculated in step  120 , the calculated value is displayed to the user in step  122  by means of the display device  24  and the filtering algorithm is then repeated. By decreasing (n) and then reducing Sum by the negative Adjust value, the size of the averaging window is halved. Referring again to step  116 , if the value of the variable n is not greater than the minimum variable value then steps  118 ,  120  and  122  are performed directly with no change to n and with Adjust=0. 
     During initialization of the algorithm shown in FIG. 4 there will be no previous sum or previous average temperature until a sufficient number of temperature measurements are taken and stored in the memory of the controller  18 . Therefore, in the embodiment shown in FIG. 4, a startup operation may be performed when the unit is turned on, before entering the continuous filtering algorithm, during which a specified number of temperature samples are taken. Using the temperature samples from the startup operation an initial Sum and average temperature (AVG) are calculated for use during the first pass through the filtering algorithm. In other embodiments the startup operation could continue for a specified amount of time rather than a specified number of passes or temperature measurements. 
     Of course, the illustrated method of reducing the responsiveness of the displayed temperature to changes in temperature within the chilling compartment when the door is opened is merely one of many possible techniques. For example, a list of previously measured temperatures may be maintained in memory and each time the temperature is displayed it may be an average of a certain number (X) of the last measured temperatures as retrieved from the list. When the door is determined to be opened X may be increased in order to increase the size of the averaging window. In another alternative, when the door is determined to be open the frequency with which the air temperature of the chilling compartment is measured may be reduced. In yet another alternative, when the door is determined to be open the frequency with which the average temperature is calculated and displayed may be reduced. 
     Further, although not illustrated in the flow chart of FIG. 4, it may also be desirable to incorporate a temperature display filtering phase out after the door has been open for a certain time period. For example, if the door is open for more than a certain time, the temperature display filtering routine may automatically begin to make adjustments, such as decreasing the size of the averaging window, to make the displayed temperature less responsive to changes in temperature within the chilling compartment so that the temperature display will alert the user to a door open problem. The certain time period may, by way of example and not by way of limitation, may be 30, 60, 90 or 120 seconds. 
     Although the invention has been described and illustrated in detail it is to be clearly understood that the same is intended by way of illustration and example only and is not intended to be taken by way of limitation. For example, while the temperature filtering method has been shown and described relative to a chiller having a chilling compartment, it is recognized that a similar filtering method could be used on other types of cooling equipment having temperature displays, such as refrigeration units. As used herein the term “cooling apparatus” is intended to encompass both chillers and refrigeration units, and the term “cooling compartment” is intended to encompass both the chilling compartment of a chiller and the refrigeration compartment of a refrigerator. 
     Other changes and modifications could be made without departing from the invention. Accordingly, the spirit and scope of the invention are to be limited only by the terms of the appended claims.