Abstract:
An apparatus for (and method of) power-management control monitors operational characteristics (such as current, compressor relay control signals, internal temperature) of an appliance during an extended period of operation, and analyzes such operational characteristics to derive a characteristic cycle time of the cooling system of the appliance. The power input port of the appliance is automatically decoupled from a power source in response to control signals provided by sensor(s) and possibly in response to additional control signals. When a predetermined set of conditions are satisfied, the power input port of the appliance is automatically coupled to the power source after expiration of a shutdown time period, which is automatically adjusted by the power management control system based upon the characteristic cycle time of the cooling system and possibly other control signals (such as an ambient temperature level provided by a temperature sensor). The apparatus for and method of power-management may be integral to an appliance. In this configuration, electrical components of the appliance (including the cooling system and possibly other electrical subsystems) are coupled/decoupled to/from the power source by the power-management control system in response to the control signal provided thereto.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to electrical systems and, more particularly, to electrical systems for reducing power consumption by electrical appliances.  
           [0003]    2. State of the Art  
           [0004]    Recent events have given urgency to what has always been a good idea: energy conservation. Energy conservation can be implemented simply by turning off power from appliances that are not in use. While power control can be done manually, e.g., people can turn off appliances when they are done using them and turn off lights as they leave a room, automated power control plays an important role in energy conservation.  
           [0005]    Timers can be used to control power delivery. For example, business lights can be turned on automatically at the start of a business day and turned off automatically at its close. Alternatively, timers can control the duration for which an appliance is active. For example, a timer might turn off a hot air hand dryer after a fixed time; anyone wanting more time can reset the hand dryer. Many appliances, such a printers, enter a low-power “sleep” mode after a set period of non-use.  
           [0006]    Ambient-light sensors can be used to control certain appliances. For example, street lamps can be activated in low light conditions, and deactivated when morning brings sufficient light that the artificial illumination is not required.  
           [0007]    Motion sensors, such as occupancy sensors, can be used to supply power only when people are present. Security lights often combine ambient-light detection and motion detection. During the day, the lights remain off regardless of motion in their vicinity; however, at night, motion triggers the lights on.  
           [0008]    Vending machines, particularly those that are refrigerated, pose special problems when it comes to energy conservation. Typically, a vending machine owner-operator places a vending machine in operation on the premises of another, and visits as necessary to refill the vending machine. The owner of the premises typically pays for the electricity consumed by the vending machine, and thus may have the biggest interest in saving power; however, the premises owner may be limited to unplugging the vending machine to save power during time of low usage.  
           [0009]    However, unplugging or switching off a refrigerated vending machine can have the undesirable consequence that the vending items may warm up. In extreme cases, this may cause items to spoil as some artificial sweeteners in diet drinks cannot survive continual thermal cycling. However, even where spoilage is not a problem, customers might have the unpleasant experience of, for example, a warm soda if they purchase soon after the vending machine is turned on. Also, the product container may be wet due to condensation on warmup. Also, unplugging or switching off a vending machine risks losing sales and customers.  
           [0010]    U.S. Pat. No. 6,243,626, commonly assigned to the assignee of the present invention, herein incorporated by reference in its entirety, discloses an appliance (e.g., vending machine) with an external power-management control subsystem that automatically couples/decouples the appliance to/from an electric power source (e.g., wall outlet) in response to control signals provided by one or more sensors/timing circuits. For example, a current sensor, time-of-day circuitry, an occupancy motion sensor, and timer circuitry can be used as inputs to a controller, which is programmed to automatically decouple the appliance from the wall outlet as follows. When the current level sensed by the current sensor is below a low threshold level, the occupancy motion sensor does not sense occupancy, and the time-of-day circuitry indicates the time is “off-hours”, the timer is set to a predetermined probationary period (for example, {fraction (1/2)} hour). During this probationary period, the inputs values are periodically evaluated to determine whether shutdown is appropriate. During such periodic evaluations, if shutdown is determined not to be appropriate, the probationary period is aborted. Yet, if during such evaluations, it is determined that shutdown is appropriate and the probationary period lapses, the controller automatically decouples the appliance from the wall outlet, thereby “shutting down” the appliance.  
           [0011]    These same inputs (and other inputs) can be used by the controller to automatically couple the appliance to the wall outlet, thereby activating the appliance. For example, any one of the following conditions can trigger the controller to automatically couple the appliance to the wall outlet: lapse of a countdown period provided by the timing circuitry; the occupancy motion sensor senses occupancy; the time-of-day circuitry indicates the time is “in-business-hours”; a temperature sensor indicates the ambient temperature level has risen to a level that requires cooling/activation of the appliance.  
           [0012]    Refrigerated vending machines utilize a compressor for cooling. It has been observed by the inventor hereof from extensive field measurements that the compressors in coin-operated beverage vending machines operate in a fairly consistent manner. In nearly all cases, the compressor will cycle from four to six times per hour. Exceptions do occur, such as when the machine is reloaded with hot product in summer. Typically, such events are transient and once the product is cooled down, the compressor operations resume to four to six cycles per hour.  
           [0013]    However, it has been observed by the inventor hereof that the compressor operations in glass front, consumer accessible beverage coolers varies broadly. The trade names for such beverage coolers are reach-in coolers, slide coolers, or visi-coolers. More specifically, it has been observed by the inventor hereof that the compressor cycling for a representative array of commercially available reach-in coolers vary from a minimum cycle time of eight minutes to a maximum cycle time of eleven hours. This extreme range of compressor cycle times can be attributed to the following factors:  
           [0014]    doors on some of these machines do not close properly, which causes leakage of cool air and extended compressor run time;  
           [0015]    glass front doors, even if operating properly, are much less energy efficient than the steel, insulated interior doors used in coin-operated beverage machines; and  
           [0016]    poor maintenance leads to clogged compressor coils and increased compressor run time.  
           [0017]    Poor maintenance occurs from the fact that service calls to reach-in coolers generally occur only when the cooling systems completely fail, which is rare. In contrast, coin-operated beverage vending machines are typically better maintained because such machines require service calls more often due to their complex coin, mechanical vending, and electronic subsystems.  
           [0018]    In such reach-in coolers (and other compressor-based appliances that have broadly varying compressor cycles), automatic power management control is difficult. More specifically, when the appliance is decoupled from its power source, it is difficult to determine when to recouple the appliance to its power source. The time period between the decoupling and recoupling of the appliance to the power source is referred to herein as the “shutdown time period.” This shutdown time period should be maximized for maximum energy saving.  
           [0019]    Thus, there remains a need in the art for automatic power-management control of a reach-in cooler (and other compressor-based appliances that have broadly varying compressor cycles) that provides enhanced power conservation.  
         SUMMARY OF THE INVENTION  
         [0020]    It is therefore an object of the invention to conserve energy usage by compressor-based appliances (such as a reach-in coolers) that experience a large range of cooling system cycle times.  
           [0021]    It is another object of the invention to provide enhanced power-management control of compressor-based appliances (such as a reach-in coolers) that experience a large range of cooling system cycle times.  
           [0022]    In accord with these objects, which will be discussed in detail below, an apparatus for and method of power-management control monitors operational characteristics (such as current, compressor relay control signals, temperature) of an appliance during an extended period of operation, and analyzes such operational characteristics to derive a characteristic cycle time of the cooling system of the appliance. The power input port of the appliance is automatically decoupled from a power source in response to control signals provided by sensor(s) and possibly in response to additional control signals. When a predetermined set of conditions are satisfied, the power input port of the appliance is automatically coupled to the power source after expiration of a shutdown time period, which is automatically adjusted by the power management control system based upon the characteristic cycle time of the cooling system and possibly other control signals (such as an ambient temperature level provided by a temperature sensor).  
           [0023]    The apparatus for and method of power-management may be integral to an appliance. In this configuration, electrical components of the appliance (including the cooling system and possibly other electrical subsystems) are coupled/decoupled to/from the power source by the power-management control system in response to control signal provided thereto.  
           [0024]    According to one embodiment of the present invention, the characteristic cycle time is derived by:  
           [0025]    i) analyzing the current levels drawn by the appliance to derive a high threshold current value whereby any current level above the high threshold current level provides an indication that the cooling system of the appliance is activated/ON;  
           [0026]    ii) analyzing the current levels drawn by the appliance to derive a low threshold current value whereby any current level below the low threshold current level provides an indication that the cooling system of the appliance is deactivated/OFF;  
           [0027]    iii) analyzing the current levels drawn by the appliance to record duration of ON time periods during which the current level drawn by the appliance is above the high threshold current;  
           [0028]    iv) analyzing the current levels drawn by the appliance to record duration of OFF time periods during which the current level drawn by the appliance is below the low threshold current;  
           [0029]    v) using the ON and OFF time period durations (for example, by adding the average ON time period duration to the average OFF time period duration) to generate the characteristic cycle time.  
           [0030]    According to other embodiments of the present invention, the cycling of the cooling system (and the characteristic cycle time of the cooling system based thereon) is identified by monitoring control signals that open and close a relay that selectively activates and deactivates the compressor of the cooling system, or by monitoring temperature (such as differential temperature across a condenser of the cooling system) within the appliance.  
           [0031]    These features enable the power-management control methodology and subsystem to automatically maximize the shutdown time period for appliances that experience large range of cooling system cycle times (such as reach-in coolers), and thus provide for maximal power conservation for such appliances.  
           [0032]    Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 is a perspective view of an exemplary embodiment of an external power-management control system  1  that controls the coupling of an appliance to a power source in accordance with the present invention.  
         [0034]    [0034]FIG. 2 is a schematic illustration of an exemplary power-management control system in accordance with the present invention.  
         [0035]    [0035]FIG. 3 is a flow chart of an exemplary power-management control scheme carried out by the power-management control system of FIG. 2.  
         [0036]    [0036]FIG. 4 is a schematic illustration of an exemplary appliance with the power-management control subsystem of FIG. 2 integrated therein in accordance with the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]    Turning now to FIG. 1, a power-management control subsystem  11  and at least one sensor  13  (one shown) cooperate to automatically manage supply of power from an electric power source  15  (e.g., wall outlet as shown) to an appliance machine  17 . Power cord  19  electrically couples the power-management control subsystem  11  to the power source  15 , and power cord  22  electrically couples the power-management control subsystem  11  to the power input port  23  of the appliance machine  17 . The output of the sensor(s)  13  is operably coupled to the power-management control subsystem  11  preferably via wiring  25  as shown. Alternately, a wireless data communication link may be used to couple the output of the sensor(s)  13  to the power-management control subsystem  11 .  
         [0038]    The power-management control subsystem  11 , which may be external to the appliance machine  17  as shown, automatically couples/decouples the power input port  23  of the appliance machine  17  to/from the power source  15  in response to control signals provided by sensor(s)  13  (and possibly in response to additional control signals, for example provided by timing circuitry, time-of-day circuitry, and a current sensor as described hereinafter in detail). The sensor(s)  13  may include a motion-based occupancy sensor (preferably realized as a passive infrared motion detector) that senses occupancy in or near the area adjacent the appliance vending machine  17  and/or a temperature sensor that senses ambient temperature. In the configuration shown in FIG. 1, the power-management control subsystem  11  and the sensor(s)  13  are preferably mounted on a support member that is releasably affixed to the appliance machine  17  as described in detail in U.S. patent application Ser. No. (Attorney Docket No. BAY-004), herein incorporated by reference in its entirety. In alternate embodiments (not shown), the power-management control subsystem  11  and possibly the sensor(s)  13  may be fastened to a wall structure adjacent the appliance machine  17 .  
         [0039]    In an alternate embodiment shown in FIG. 4, the power-management control subsystem  11  and possibly the sensor(s)  13  are integral to the appliance machine  17 . In such a configuration, the power-management control subsystem  11  and cooling system  27  of the appliance  17  are disposed within a common system housing  29  as shown, and the power-management control subsystem  11  manages supply of power to the cooling system  27  (and possibly to other electric systems  28  of the appliance) utilizing the power management operations described herein.  
         [0040]    The power-management control subsystem  11  may be adapted to act as a master controller by forwarding sensor status information (derived from the output of the sensor(s)  13 ) to other power-management control subsystems  11 ′ (slave controller(s)) operably coupled thereto as shown in FIG. 1, which is typically found in applications where a bank of vending machines are co-located in a facility. Preferably, the master power-management control subsystem  11  forwards such sensor status information by asserting a signal which is then electrically isolated, typically using an opt-coupler, before connection to the slave power management control system(s)  11 ′. Isolating this signal eliminates voltage differences between the master and slave power-management control subsystems, which may occur in the event that the two subsystems are plugged into outlets on separate electrical circuits. Repeating the sensor status information from the master power-management control subsystem  11  to the slave power-management control subsystem(s)  11 ′ allows each slave power-management control subsystem  11 ′ to automatically manage supply of power from an electric power source to an appliance machine(s) operably coupled thereto without the need for sensors, thereby reducing the cost of the overall power management control system. Also, this repeating function allows the master power-management control subsystem  11  to delay the sending of such sensor status information for a small time period (e.g., few seconds) so that when occupancy is detected, the bank of appliance machines controlled by the chain of power-management control subsystems will power up sequentially and not in unison. Sequential power-up prevents electrical surges that might trip circuit protection devices such as circuit breakers.  
         [0041]    [0041]FIG. 2 is a schematic diagram of an exemplary power-management control system  1 . The power-management control subsystem  11  is disposed electrically between an electrical power source (e.g., wall socket)  15  and an appliance machine  17 . The subsystem  11  includes a switch  30  that, when in its “ON” condition, electrically couples the input power port  23  of the appliance machine  17  to wall socket  15 . In its “OFF” condition, indicated in phantom in FIG. 2, switch  30  causes the input power port  23  of the appliance machine  17  to be decoupled electrically from the power source  15 .  
         [0042]    Power switch  30  has a control input  32  that is coupled to a controller  34 . Through its connection to control input  32 , controller  34  controls when switch  30  is in its ON condition and when it is in its OFF condition. Controller  34  determines the appropriate condition for switch  30  at any given time as a function of present and past readings from a current sensor  35 , a temperature sensor  13 - 1 , an occupancy sensor  13 - 2 , and a time-of-day circuit  39  (an absolute time sensor). In addition, subsystem  11  includes a timer  38  for elapsed time indications and a random-access memory  36  for storing data for use by controller  34 . Thus, each of these devices is coupled to the controller  34  so as to provide respective parameter readings thereto.  
         [0043]    Alternative embodiments of the invention omit one or more of the current sensor  35 , the temperature sensor  18 , the occupancy sensor  20 , and the time-of-day circuit  39 . Also, some embodiments include a time-of-day circuit  39  that is used to provide data from which a controller calculates elapsed time, thus dispensing with the need for a separate timer circuit  38 .  
         [0044]    The appliance machine  17  may be a glass front, consumer accessible beverage cooler (sometimes referred to as a reach-in cooler, slide cooler or visi-cooler) that includes a glass door  8  and a plurality of shelves  9  as shown in FIG. 1. The shelves  9  support beverage containers (not shown) that are all visible and therefore available for access by customers. Alternatively, the appliance machine  17  may be another appliance that exhibits a large range of cooling system cycle times.  
         [0045]    [0045]FIG. 3 is a flow chart illustrating an exemplary power-management control scheme carried out by the power-management control system  1  of FIG. 2. The control operations begin in block S 10  where data is collected and is used to build a profile of appliance machine  17 , which is stored in memory  36 . This profile includes the characteristic cycle time (t c ) of the cooling system of the appliance machine  17 . For example, minima and maxima of the current levels drawn by the appliance machine  17  (measured by current sensor  35 ) are recorded and stored by controller  34  in memory  36 . Current thresholds are calculated by controller  34  as a function of the minima and maxima current levels and are also stored in memory  36 . Such current thresholds preferably include a high threshold current level that provides an indication that the cooling system of the appliance is activated/ON, and a low threshold current value that provides an indication that the cooling system of the appliance is deactivated/OFF. Between the high and low threshold current levels is an indeterminate or transition range that can be used to introduce hysteresis into the determination of when to remove power from the appliance vending machine  17 . In addition, the controller  34  preferably calculates durations of ON time periods during which the current level drawn by the appliance is above the high threshold current in addition to durations of the OFF time periods during which the current level drawn by the appliance is below the low threshold current, and stores the durations of such ON time periods and the durations of such OFF time periods in memory  36 . The controller  34  calculates the characteristic cycle time (t c ) of the cooling system of the appliance machine  17  as a function of such ON time period durations and OFF time period durations (for example, by adding the average ON time period duration to the average OFF time period duration), and stores the characteristic cycle time (t c ) in memory  36 . During the appliance profiling operations of block S 10 , the switch  30  is placed in its ON condition so that power is supplied from power source  15  to the appliance machine  17 . In addition, the duration of the profiling operations of block S 10  is set for an extended period of time that encompasses at least one expected cycle time (and possibly one to twenty expected cycle times) of the cooling system of the appliance machine  17 . For glass front, consumer accessible beverage cooler appliances, this extended period of time is typically on the order of 12 to 48 hours, such as a 24 hour time period. In this manner, the profiling operations of block S 10  build an accurate estimate of the characteristic cycle time of the cooling system of the appliance machine  17 .  
         [0046]    Alternatively, in the profiling operations of block S 10 , the cycling of the cooling system of the appliance may be identified by monitoring control signals that open and close a relay that selectively activates and deactivates the compressor of the cooling system, or by monitoring temperature (such as differential temperature across a condenser of the cooling system) within the appliance. In this configuration, the characteristic cycle time of the cooling system is based upon the time durations of the cycle(s) of the cooling system during the extended time period of the profiling operations of block S 10 .  
         [0047]    After profiling is accomplished at block S 10 , the operations of the power management control scheme continue to block S 12 . Note that the operations of block S 11  (wherein the switch  30  is placed in its ON condition so that power is supplied from power source  15  to the appliance machine  17 ) are bypassed because the switch  30  has already been placed in its ON condition during the profiling operations of block S 10 .  
         [0048]    In block S 12 , current, temperature, occupancy, and absolute time parameters are monitored. The monitoring is ongoing even as subsequent blocks are performed.  
         [0049]    In blocks S 14  through S 17 , parameters monitored in block S 12  are used to determine whether to maintain switch  30  in the ON condition or switch it into the OFF condition (thereby shutting down the appliance machine  17 ). In particular, in block S 14 , it is determined whether the parameters indicate that the switch  30  should be maintained in the ON condition or switched into the OFF condition (thereby shutting down the appliance machine  17 ). For example, if the current level identified by current sensor  35  is high (indicated usage or a compressor cycle), if the occupancy sensor  13 - 2  determines that occupancy is positive, or if the absolute time provided by time-of-day circuit  39  is during “business hours”, the appliance machine  17  is not shut down. In this case, operations return to the monitoring block S 12 . However, if the current level identified by current sensor  35  is below the low threshold, the occupancy sensor  13 - 2  determines that occupancy is negative, and the absolute time provided by time-of-day circuit  39  is during “off hours”, then the timer  38  is set for a probationary period (e.g., half an hour time period) at block S 15 .  
         [0050]    During this probationary period (blocks S 16 , S 17 ), the present values of the parameters are evaluated repetitively to determine whether any parameter changes to a value which would indicate that shut down is not appropriate. If there is such a change, the countdown is aborted and operations return to monitoring in block S 12 . More specifically, if the current exceeds the upper threshold, occupancy becomes positive, or the time-of-day becomes “business hours”, the probationary countdown is aborted. If the parameter values remain within the range for which shut down is appropriate and the end of “probationary” countdown period is detected in block S 17 , the operations continue at block S 18 .  
         [0051]    In block S 18 , the controller  34  calculates a shutdown time period (that will be used to initialize the timer  38  in block S 22 ) as a function of the characteristic cycle time (t c ) calculated in block S 10  and possibly as a function of ambient temperature (as sensed by the temperature sensor  13 - 1 ). For example, the shutdown time period my be calculated by adding the characteristic cycle time (t c ) to an offset time period that is based on ambient temperature.  
         [0052]    The control operations of block S 18  continue to block S 21 , wherein the switch  30  is placed in its OFF condition so that the power source  15  is decoupled from the appliance machine  17 , and operations continue to block S 22 . In block S 22 , timer  38  is set to the shutdown time period determined in block S 18 , and the operations continue at block S 23 . In block S 23 , parameters other than current are monitored. At block S 24 , if it is found that the parameter values call for activating the appliance machine  17 , operations jump to block S 11  and the switch  30  is set in its ON condition. Otherwise, operations continue to block S 25 .  
         [0053]    In block S 24 , activation can be caused by:  
         [0054]    i) the occupancy sensor  13 - 2  providing an indication that occupancy is positive;  
         [0055]    ii) transition of the absolute time provided by time-of-day circuit  39  into “business hours”; or  
         [0056]    iii) an increase in temperature measured by temperature sensor  13 - 1  to an ambient temperature level requiring cooling of contents.  
         [0057]    In block S 25 , if the expiration of the shutdown time period is detected, the operations jump to block S 11  and the switch  30  is set in its ON condition. Otherwise, operations return to the monitoring operations of block S 23 .  
         [0058]    By monitoring the operational characteristics (e.g., current compressor relay control signals, internal temperature) of the appliance over an extended period of time and building a profile of the appliance that includes the characteristic cycle time (t c ) of the cooling system of the appliance, the control scheme of FIG. 3 gathers and maintains information about the appliance that can permit more intelligent power-management. These features enable the power-management control subsystem to automatically maximize the shutdown time period for compressor-based appliances (such as a reach-in coolers) that experience a large range of cooling system cycle times, and thus provide for maximal power conservation for such appliances.  
         [0059]    There have been described and illustrated herein several embodiments of a power-management control system and intelligent power control methodologies/schemes for use with beverage coolers. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, the invention applies more generally to other appliances, including those that vary the current they draw in accordance with internal activity. Most electromechanical appliances are in this category. Moreover, while particular configurations of control architectures and schemes have been disclosed, it will be appreciated that other configurations could be used as well. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.