Wireless system for preventing condensation on refrigerator doors and frames

Abstract

The present invention is an improved anti-sweat controller for removing condensation from glass doors that are used on refrigerators in retail stores. The anti-sweat controller comprises three components, a sensor to measure condensation and temperature, a control unit to adjust door heaters, and a command unit. The sensors, control unit, and command unit all communicate on a wireless peer-to-peer network using the ZigBee protocol. Moreover, the command unit is attached to the Internet and enables a user to adjust the various settings on the anti-sweat controller from a remote location if desired.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and is a continuation-in-part of co-pending application Ser. No. 10/778,289 filed Feb. 11, 2004 which is hereby incorporated herein by reference.

FIELD OF INVENTION

[0002] This invention relates generally to refrigeration devices. This invention relates particularly to a wireless device for reducing energy consumption by refrigerator door and frame heaters while maintaining protection against condensation.

BACKGROUND

[0003] Shopkeepers display refrigerated or frozen products in temperature-controlled display cases, such as refrigerators with glass display doors or open-air, "coffin," coolers. The refrigerators and freezers are referred to herein as "refrigerators." Changes in temperature and humidity in the surrounding area cause condensation and frost to build up on the refrigerators. This obstructs visibility of the products and can cause unsafe conditions as the condensation falls to the floor. As a result, it is desirable to prevent the build-up of condensation and frost on refrigerators.

[0004] To combat condensation and frost, heaters are installed in refrigerator doors and frames, which raise the temperature of the door or frame sufficiently to eliminate condensation. Typically these heaters run constantly, but devices that control whether the heaters are on or off are known in the art. They are referred to generally as anti-sweat controllers. One anti-sweat controller known in the art attaches one or more condensation sensors to the refrigerator door or the frame and turns on a door heater when condensation is sensed. Traditionally, a single control box is used to control all the sensors of a given refrigerator. These devices fail, however, to prevent condensation because the heater is not activated until after condensation is sensed. Another version uses a humidistat to sense humidity in the aisle and, when the humidity goes above a given level, the heater is turned on, often regardless of whether condensation is actually present. This increases energy consumption because the heater is either constantly on or turned on unnecessarily. It would be desirable to prevent condensation with the minimum amount of heat, and consequent energy expenditure, necessary.

[0005] Known anti-sweat controllers connect the control box to the sensors with wires that transmit and receive data between the sensors and control boxes. For example, if a sensor detected a certain level of humidity on the refrigerator door, the sensor would transmit a signal through the wire to the control box directing that the control box turn the heater on to remove humidity and associated condensation from the door. Hardwiring the various sensors to the control box is problematic as it increases the time needed to install anti-sweat controllers. Additionally, the wires can be accidentally cut which results in a non-functioning anti-sweat controller which may require a qualified repairman to fix. It would be desirable to provide an anti-sweat controller that utilized wireless sensors to communicate with the control box to eliminate these communication wires.

[0006] Additionally, anti-sweat controllers are also hardwired into the local power source, which results in difficult access for repair and replacement because the anti-sweat controllers must be unwired each time they are removed and rewired each time they are reinstalled. If the anti-sweat controller breaks, the fact that the system is integral with the local power source may cause the shopkeeper to be unable to set the system to keep the heaters on until a qualified repairman fixes the problem. Further, the dismantling and reconstruction cause safety issues while obstructing customer access to the refrigerators. It would be desirable to provide an anti-sweat controller that is connected to the power source with a quick-disconnect plug enabling it to be easier to install, repair and replace and that provides a means for the shopkeeper to mitigate problems if a controller fails.

[0007] The controller box controls a number of factors that must be set correctly to reduce energy consumption and eliminate condensation, such as sensitivity of the sensor and how long the heater stays on or off once signaled. To date, these factors have been measured and controlled by manually adjusting various currents and voltages on each control box with a multimeter. For a store with multiple refrigerators and multiple anti-sweat controllers, the multimeter must be plugged into each separate controller in order to adjust the entire system. Detecting the specific location of an electrical failure is frustrating and time consuming due to the need to test each separate device. Balancing the system becomes tedious. As a result, it is desirable to reprogram, monitor, and control an anti-sweat controller system without having to plug into each control box on each refrigerator and without having to make on-site visits to each store. Specifically, it would be desirable to provide a control box that could be programmed from a remote location using the Internet.

[0008] Therefore, it is an object of this invention to provide an anti-sweat controller that operates a heater where condensation has not yet been detected but is anticipated. It is another object of this invention to provide ease of programming, repair, and reinstallation by providing an anti-sweat controller with sensors and control boxes that communicate wirelessly. It is a further object to provide a system that can be set to a heater-on state if a problem arises with the anti-sweat controller. It is an additional object of the invention to provide remote monitoring and control of an anti-sweat controller over the Internet.

SUMMARY OF THE INVENTION

[0009] The present invention is a device for reducing energy consumption of heaters on refrigerator doors and frames. A control unit is set so that the heater is on prior to the formation of condensation. The preferred embodiment provides a door heating system that only turns on the heater when condensation is present to conserve energy. The heater may also be turned on when condensation is sensed by a sensor, and the sensor reading may be used to override the preset times. The control unit and sensors are capable of transmitting and receiving data wirelessly which eliminates the need for hardwiring the sensors to the control units. In the preferred embodiment, a command unit is used to enable remote monitoring and control of the control units and sensors and communicates wirelessly with the control units and sensors. The command unit is connected to the Internet to enable a user to monitor and control the anti-sweat controller from a remote location.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 illustrates an anti-sweat controller installed on a refrigerator according to the present invention;

[0011] FIG. 2 illustrates a control unit according to the present invention;

[0012] FIG. 3 is a block diagram of the command unit; and

[0013] FIG. 4 illustrates the anti-sweat controller including the sensor installed on a single refrigerator door and the control unit which are in operative communication with the command unit.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Referring to FIGS. 1-4, the system comprises a control unit 110, one or more sensors 114, and preferably a command unit 120. The system is used to prevent condensation on the doors and frames of a refrigerator 111 in conjunction with a heater (not shown, but usually incorporated in the door or on the frame) and a control unit power source 115. Control unit 110, sensors 114 and command unit 120 are each equipped with a transceiver 113 to receive and transmit data wirelessly. Control unit 110 is typically located apart from the door heaters and may operate multiple doors. In the preferred embodiment, the control unit operates approximately four heaters on four different refrigerator doors or frames. Control unit 110 communicates with the command unit 120 and one or more sensors 114 on the wireless network and is connected to control unit power source 115. In the preferred embodiment, command unit 120 is connected to an information technology network and is capable of transmitting data gathered from control unit 110 and sensors 114 over the Internet to a user such as a shopkeeper who can then monitor and adjust control unit 110 and sensors 114 from a remote location.

[0015] In contrast to prior art anti-sweat controllers which relied on discrete and analog components, the present invention utilizes integrated circuits and digital transmissions for increased sensitivity, control, and reliability. For ease of installation with known performance characteristics, control unit 110 preferably uses modular connectors known in the art to connect to the various door heaters. Control unit 110 can usually control up to six door heaters, therefore, if a particular store has more than six heaters, additional control unit(s) 110 may be needed. Control unit(s) 110 preferably further comprises a computer processor 160, preferably a custom-programmed microcontroller that includes a timer, memory and an analog-to-digital converter. A preferred microcontroller is available from Freescale Semiconductor, Inc. of Austin, Tex. and sold as part number MC9S08GT60. Control unit 110 is capable of being programmed to turn the heaters on and off at certain times.

[0016] While control unit 110 is hard-wired to the heaters to deliver power to the heaters, control unit 110 communicates wirelessly with sensors 114, command unit 120, and, if present, other control units 110. As shown in FIG. 1, an electrical wire 112 connects control unit 110 to other control units 110. Control unit 110 is also equipped for wireless communication with known wireless communication equipment including the custom-programmed microcontroller on a wireless peer-to-peer network or a star topology physical network using the Zigbee protocol.

[0017] As shown in FIGS. 1 and 4, sensors 114 are attached to the refrigerator, positioned uniquely for each refrigerator where condensation forms the soonest, such as on the door jams, headers, or mullions. In the preferred embodiment, the sensors are located on the door frames. Sensors 114 are capacitive sensors in the preferred embodiment and capable of detecting both relative humidity levels and temperature. Each sensor 114 is equipped to communicate wirelessly on the peer-to-peer or star topology network of other sensors 114, control unit(s) 110 and command unit 120, preferably using a ZigBee protocol network. Specifically, sensors 114 receive wireless data from control unit 110. In this embodiment, sensors 114 are adjusted by sending data through control unit 110 which in turn adjusts sensors 114. However, sensors capable of individual adjustment without requiring control unit 110 could certainly be used and fall within the scope of the present invention. An example of an acceptable sensor is a Humerel.RTM. sensor produced by Measurement Specialist, Inc. of Hampton, Virginia.

[0018] Control unit 110 receives data wirelessly from sensors 114 related to a particular door's temperature or the humidity within a refrigerator and compares that data to thresholds contained within a database. If a certain temperature or humidity threshold has been reached at a specific door or refrigerator, control unit 110 will direct that the heater associated with that refrigerator turn "on" until the humidity and temperature level are restored to acceptable levels. The times that control unit 110 directs certain heaters to turn on can be adjusted by sending wireless commands to control unit 110 from command unit 120 as described below or they can be adjusted using a personal data assistant or PDA device that is equipped to receive and transmit data on the Zigbee protocol directly to control unit 110.

[0019] Command unit 120 is generally located apart from the refrigerator doors and communicates with the various sensors 114 and control unit 110 to enable a user to adjust certain thresholds or settings within control unit 110 and sensors 114. Command unit 120 is connected to a computer 121 (preferably a personal computer) by an Ethernet connection in the preferred embodiment and enables a user to adjust control unit 110 thereby adjusting sensors 114 or the heaters. This adjustment can be made at computer 121 or at another computer via the Internet if computer 121 is connected to the Internet.

[0020] As shown in FIGS. 3, command unit 120 comprises a microcontroller 80, command unit power source 82, transceiver 113, and memory 84. Microcontroller 80 preferably includes an integrated Ethernet Media Access Controller and 10/100 Ethernet Physical Layer and on-chip flash memory. In the preferred embodiment, microcontroller 80 is custom programmed for this specific application as known in the art. An acceptable microcontroller 80 is available from Freescale Semiconductor, Inc. and sold as part number MC9S12NE64. To protect the various components from damage, command unit 120 can include a housing. An acceptable housing is available from Hammond Manufacturing of Cheektowaga, N.Y. and sold as part number 1593X. Additionally, command unit power source 82 can either be batteries or alternating current that has been adjusted by a transformer such as a wall wort.

[0021] Command unit 120 adjusts various values via control unit 110, such as lowering the set point of sensor 114 and thereby decreasing sensitivity. For example, if the set point of a particular sensor 114 is set high, such that the heater is instructed to turn on when very little humidity is present, the heater will turn on as the lightest condensation occurs. However, if the sensitivity is set lower, such that the heater turns on only when significantly more humidity is measured, the heater will turn on when more condensation is present. Ideally the sensitivity is adjusted to maintain an optimum balance between condensation and the amount of time the heater is on. Of course, the less the heater is on, the less energy is consumed by the system and the lower the energy costs. Command unit 120 is also used to set start and stop times, as discussed in more detail below, which work in cooperation with the sensor setting. Proper settings enable the shopkeeper to achieve demand savings, i.e., reducing power consumption during higher-rate periods, as well as savings due to overall power consumption.

[0022] To anticipate condensation, the control unit 110 signals when the heater should be on prior to the formation of condensation, for example, at preset start and stop times consistent with when condensation is anticipated. For example, in the context of supermarket refrigerator doors, preset start times could be set to once every hour, on the hour, between 6 a.m. and 9 a.m., 12 p.m. and 1 p.m., and 5 p.m. and 9 p.m. (times corresponding to when the supermarket is very busy, refrigerator doors are repeatedly opened, and condensation is anticipated). Preferably preset stop times are set to provide for 15 minute duty cycles. These preset times work in cooperation with sensors 114, and the sensor 114 measurements can override the preset times. For example, in the event the pre-set cycle time is insufficient to prevent condensation, the sensor reading can override the pre-set "off" time and cause the heater to run until no more condensation is detected. Computer 121 is equipped with software which is used to adjust the various preset start and stop times of the control unit 110. Data entered on computer 121 by a user (such as a shopkeeper) is sent to command unit 120 and then wirelessly transmitted to control unit 110.

[0023] A quick-disconnect coupling 140 connects each control unit 110 to the control unit power source 115. Coupling 140 is preferably a mate and lock connector, with four prongs 143, as shown in FIG. 2. Other quick-disconnect plugs that provide simple, rapid separation of the spliced wires without the use of tools may be used. Coupling 140 enables a shopkeeper to disconnect the control unit 110 from the heaters without unwiring the system, which allows the heaters to revert to their always-on state and prevent condensation until a qualified repairman can fix the system. Alternatively, the heaters can be turned completely off. Coupling 140 also provides for a control unit 110 to be removed and installed much more safely and quickly than prior art devices. Control unit power source 115 is preferably an AC power supply, such as a circuit off of the mains.

[0024] While command unit 120 isn't necessary for the anti-sweat controller to function, it is used in the preferred embodiment to enable a user to easily monitor and adjust control unit 110 and sensors 114 from a remote location. As noted above, command unit 120 is capable of receiving data from control unit 110 and sensors 114 and storing the data in a database. Computer 121 can transmit that data over the Internet to any other computer that is connected to the Internet. In the preferred embodiment, a shopkeeper would be able to review the data in the database on the Internet. The shopkeeper could view data collected in the database relating to the various times that the heaters turned on and off to reduce humidity and condensation within the refrigerator and make adjustments if necessary. The ability to adjust the various heaters and review the data collected in the database is greatly simplified since the control unit 110, sensors 114, and command unit 120 communicate on a wireless network.

[0025] While any wireless communication standard can be used and fall within the scope of the present invention, the IEEE 802.15.4 standard (commonly known as a ZigBee wireless network) is preferred. In this regard, data is sent in packets to and from the respective transceivers 113 on the control unit 110, sensors 114, and command unit 120. The IEEE 802.15.14 standard for Wireless Medium Access Control (MAC) and Physical Layer Specifications for Low-Rate Wireless Personal Area Networks (LR-WPANs) is available from the Institute of Electrical and Electronics Engineers, Inc. of New York, N.Y., and is herein incorporated by reference. Other short-range, wireless networks could be used and fall within the scope of the present invention including a Bluetooth wireless network.

[0026] The advantages of the anti-sweat controller of the preset invention can be illustrated by the following example. In a store with approximately 10 refrigerators, the control unit(s) 110 may be set to turn the heaters on at peak times, at 7:30 A.M. and 5:00 P.M. and cycle the heaters for a 15 minute interval. Throughout a given week, five out of ten heaters are only activated at that preset times as the humidity and temperature levels in those refrigerators are below the thresholds programmed into control unit 110 for sensors 114 to activate the heaters. But, the humidity and temperature within the remaining five refrigerators does reach the particular threshold directing that sensors 114 send signals to control unit(s) 110 to turn on the door heaters to remove the condensation from the door. The control unit(s) 110 transmits wireless data related to the time that the heaters turned on and the duration that they were on to command unit 120 which transfers this data into the database.

[0027] Since command unit 120 is connected to computer 121, this data is available to be accessed over the Internet. The shopkeeper can log onto the database via the Internet and view that data which shows that the heaters are being activated for five out of the ten refrigerators at 3:00 P.M. Monday-Friday during the week. Upon reviewing this data, the shopkeeper decides to modify the settings for the heaters in the five refrigerators so that they are activated a 2:50 P.M. in an effort to prevent condensation before it is likely to form. The shopkeeper simply makes the adjustment on a computer which is sent over the Internet to computer 121 which in turn transmits this adjustment data to command unit 120. Command unit 120 wirelessly transmits this adjustment data to control unit(s) 110 which are programmed to turn on the heaters at 2:50 P.M. in addition to the normal times of 7:30 A.M. and 5:00 P.M.

[0028] Therefore, the shopkeeper can monitor and control the anti-sweat controllers for a given store in any location where Internet access is available. Moreover, the number of anti-sweat controllers that can be monitored in this fashion is unlimited. Therefore, a shopkeeper can monitor the door heaters in a single store or dozens of stores in different locations if he so desires. Additionally, because the anti-sweat controller's operation can be monitored via the Internet, it is easier to diagnose if a problem exists. For example, if a heater fails, a shopkeeper can view the data about the operation of the anti-sweat controller and easily determine which heater is malfunctioning.

[0029] While there has been illustrated and described what is at present considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the true scope of the invention. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A system for reducing energy consumption by a heater on a refrigerator door comprising: a) a control unit comprising a computer processor having memory and a timer, the control unit connected to the heater; b) a sensor attached to the refrigerator door that senses relative humidity and directs that the control unit turn on the heater when condensation is likely to be on the refrigerator door; d) wherein the sensor and control unit are equipped with wireless communication devices that enable them to transmit and receive data.

2. The system according to claim 1 further comprising a command unit that communicates wirelessly with both the sensor and the control unit.

3. The system according to claim 2 wherein the command unit is connected to the Internet and capable of transmitting data from the sensor and control unit over the Internet to a user.

4. The system according to claim 3 wherein the user can control and adjust the sensor and heater at a computer connected to the Internet that receives data from the command unit.

5. The system according to claim 2 wherein the sensor is a capacitive sensor.

6. The system according to claim 2 wherein the sensor is capable of sensing temperature as well as humidity.

7. The system according to claims 2 wherein the sensor, control unit, and command unit communicate on a ZigBee wireless network compliant to the IEEE 802.15.4 standard.

8. A system for reducing energy consumption by a heater on a refrigerator, the system comprising: a) a heater; b) a control unit connected to the heater that turns the heater on and off at predetermined times and transmits and receives data wirelessly; c) at least one sensor that senses the presence of humidity or a change in temperature that transmits and receives data wirelessly; d) a command unit that transmits and receives wireless data from the control unit and at least one sensor; and e) a first computer connected to the command unit that transmits the data received from the control unit and sensor(s) to a second computer over the Internet.

9. The system of claim 8 wherein the user can control the heater and adjust the predetermined times that the heater turns on and off by using the second computer to transmit data over the Internet to direct the control unit to adjust the predetermined times when the heater is turned on and off.

10. The system according to claim 8 wherein at least one sensor is a capacitive sensor.

11. The system according to claim 8 wherein the heater and at least one sensor are located on the same refrigeration compartment door.

12. The system according to claim 11 further comprising additional refrigeration compartment doors, each of which contains a separate heater and at least one sensor.

13. The system according to claim 12 wherein the command unit receives data from the control unit and at least one sensor on all the refrigeration compartment doors.

14. The system according to claim 8 wherein the at least one sensor, control unit, and command unit communicate on a wireless peer-to-peer network.

15. The system according to claim 8 wherein the command unit transfers the data received from the at least one sensor into a database.

16. A method for remotely monitoring and controlling refrigerator door heaters comprising: a) providing a first group of refrigeration compartments with at least one door wherein each door comprises a heater and a sensor that is capable of wireless data transmission to and from a control unit; b) providing a first command unit that communicates wirelessly with at least one sensor and control unit; c) connecting the first command unit to the Internet; d) using the first command unit to transmit data from the control unit and at least one sensor over the Internet to a computer operated by a user; and e) enabling the user to adjust the heating system from a remote location by transmitting commands entered by the user at the computer to the first command unit over the Internet.

17. The method according to claim 16 further comprising: a) providing a second group of refrigeration compartments in a different location than the first group of refrigeration compartments, wherein each door comprises a heater and a sensor that is capable of wireless data transmission to and from a control unit; b) providing a second command unit that communicates wirelessly with at least one sensor and control unit on the second group of refrigeration compartments; c) connecting the second command unit to the Internet; d) using the second command unit to transmit data from the command unit and at least one sensor located on the second group of refrigeration compartments over the Internet to a computer operated by a user; and e) enabling the user to individually adjust the heating system in either the first or second groups of refrigeration compartments from a remote location by transmitting commands entered by the user at the computer to the first and second command units over the Internet.

18. The method according to claim 16 further comprising the step of providing a database that collects and stores data related to the operation of the control units and sensors that the user is able to access over the Internet.

19. The method according to claim 17 further comprising the step of providing a database that collects and stores data from the first and second command units that the user is able to access.

20. The method according to claim 16 wherein all the wireless data transmission occurs on a ZigBee wireless network compliant to the IEEE 802.15.4 standard.

21. A method for remotely monitoring and controlling refrigerator door heaters comprising: a) providing a first group of refrigeration compartments with at least one door wherein each door comprises a heater and a sensor that is capable of wireless data transmission to and from a control unit; b) providing a first command unit that communicates wirelessly with at least one sensor and control unit; c) connecting the first command unit to the Internet; d) using the first command unit to transmit data from the control unit and at least one sensor over the Internet to a computer operated by a user; and e) enabling the user to verify that the system is operating properly and to correctly identify whether a particular component is malfunctioning.