System and method for controlling temperature of a liquid residing within a tank

• US 7,603,204 B2
• Filed: 04/21/2006
• Issued: 10/13/2009
• Est. Priority Date: 11/15/2001
• Status: Expired due to Fees

• Current Assignee: A. O. Smith Corporation
• Original Assignee: A. O. Smith Corporation
• Inventors: Patterson, Wade C., Phillips, Terry G.
• Primary Examiner(s): Bahta; Kidest
• Application Number:
  US11/409,229
• Publication Number:
  US 20060190141A1
• Time in Patent Office: 1,271 Days
• Field of Search: 700299-300, 219/497, 219/483, 219/490, 219/509, 432/36, 432/44
• US Class Current: 700/299
• CPC Class Codes: F24D 17/0031 with accumulation of the heated water
• CPC Class Codes: F24H 15/14 Cleaning; Sterilising; Preventing contamination by bacteria or microorganisms, e.g. by replacing fluid in tanks or conduits
• CPC Class Codes: F24H 15/172 Scheduling based on user demand, e.g. determining starting point of heating
• CPC Class Codes: F24H 15/174 Supplying heated water with desired temperature or desired range of temperature
• CPC Class Codes: F24H 15/223 in the water storage tank
• CPC Class Codes: F24H 15/269 Time, e.g. hour or date
• CPC Class Codes: F24H 15/281 Input from user
• CPC Class Codes: F24H 15/37 of electric heaters
• CPC Class Codes: F24H 15/395 Information to users, e.g. alarms
• CPC Class Codes: F24H 15/421 using pre-stored data
• CPC Class Codes: F24H 15/45 remotely accessible
• CPC Class Codes: F24H 15/486 using timers
• CPC Class Codes: F24H 9/2021 Storage heaters
• CPC Class Codes: F24H 9/28 characterised by the graphical user interface [GUI]
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature
• CPC Class Codes: G05D 23/1917 using digital means
• CPC Class Codes: G05D 23/1951 with control of the working time of a temperature controlling device

Abstract

A system for controlling a temperature of a liquid residing within a tank comprises a temperature sensor, a temperature control element, memory, and logic. The temperature sensor is configured to detect the temperature of the liquid residing within the tank, and the temperature control element is coupled to the tank. The memory stores data indicative of a usage history of the tank, and the logic is configured to automatically control the temperature control element based on the data.

Claims

1. A system for controlling a temperature of a liquid residing within a tank, comprising:

a temperature sensor configured to detect the temperature of the liquid;

a temperature control element configured to alter the temperature of the liquid, the temperature control element having at least an activated state and a deactivated state, wherein heat is applied to the liquid when the temperature control element is in the activated state;

a clock; and

logic configured to maintain the temperature of the liquid at a first temperature threshold by adjusting the temperature control element between the activated state and the deactivated state during each of a first plurality of time periods,

the logic further configured to monitor usage of the temperature control element by determining an amount of time that the temperature control element is in the activated state during each of the first plurality of time periods based on a time value indicated by the clock, and

the logic further configured to maintain the temperature of the liquid at a second temperature threshold by adjusting the temperature control element between the activated state and the deactivated state during a subsequent time period corresponding to one of the first plurality of time periods, wherein the second temperature threshold is automatically selected based on the amount of time that the temperature control element was determined to be in the activated state during the one of the first plurality of time periods corresponding to the subsequent time period.

2. The system of claim 1, wherein the temperature control element comprises a heating element.

3. The system of claim 1, wherein the logic is further configured to activate and deactivate the temperature control element during the first plurality of time periods based on the first temperature threshold and a third temperature threshold, thereby providing a first activation hysteresis for the temperature control element between the first and third temperature thresholds, the logic further configured to activate and deactivate the temperature control element during the subsequent time period based on the second temperature threshold and a fourth temperature threshold thereby providing a second activation hysteresis for the temperature control element between the second and fourth temperature thresholds, wherein a difference between the first and third temperature thresholds is different than a difference between the second and fourth temperature thresholds.

4. The system of claim 1, wherein the logic is further configured to automatically generate data indicative of a usage history of the temperature control element, wherein the data defines a schedule, the schedule having a plurality of time slots, each time slot associated with a respective temperature threshold by the data depending on a total amount of time that the temperature control element is activated during a corresponding time period, and wherein the logic is configured to select the second threshold by identifying a time slot corresponding to the subsequent time period and determining the respective temperature threshold associated with the time slot corresponding to the subsequent time period.

14. The system of claim 1, wherein the logic is configured to define a schedule of expected usage for the temperature control element based on a usage history of the temperature control element, the schedule having predefined time slots, wherein one of the time slots corresponds to the subsequent time period, and wherein the logic is configured to classify the one time slot based on the amount of time that the temperature control element is determined, by the logic, to be in the activated state during the one of the first plurality of time periods corresponding to the subsequent time period.

15. The system of claim 14, wherein the logic is configured to determine an amount of time that the temperature control element is in the activated state during the subsequent time period and to determine whether the one time slot has been misclassified based on the amount of time that the temperature control element is in the activated state during the subsequent time period, and wherein the logic is configured to change a classification of the one time slot based on a determination that the one time slot has been misclassified.

5. A system, comprising:

a tank;

a temperature sensor configured to detect a temperature of a liquid residing within the tank;

a temperature control element coupled to the tank, the temperature control element having an activated state and a deactivated state;

a computer-readable memory storing data indicative of a usage history of the temperature control element; and

logic configured to maintain the temperature of the liquid residing within the tank at a threshold by adjusting the temperature control element between the activated state and the deactivated state,

the logic further configured to track an amount of time that the temperature control element is in the activated state during each of a plurality of reoccurring time periods in order to automatically define the data indicative of the usage history, and

the logic further configured to automatically select the threshold during one of the plurality of reoccurring time periods based upon previously stored data indicative of the usage history during one or more previous occurrences of the reoccurring time period.

6. The system of claim 5, wherein the logic is configured to ensure that the temperature control element is periodically controlled such that an amount of bacteria within the tank remains within a desired range.

7. The system of claim 5, wherein the logic is configured to control the temperature control element such that the temperature control element has a first activation hysteresis between a first temperature threshold and a second temperature threshold, wherein the logic is configured to place the temperature control element in the activated state when a sensed temperature falls below the first temperature threshold and to place the temperature control element in the deactivate state when the sensed temperature exceeds the second temperature threshold.

8. The system of claim 7, wherein the logic is configured to transition the temperature control element from the first activation hysteresis to a second activation hysteresis when the usage history data indicates that a time period of high usage is imminent,

wherein during the second activation hysteresis, the logic configured to place the temperature control element in the activated state when the sensed temperature falls below a third temperature threshold and to place the temperature control element in the deactivated state when the sensed temperature exceeds a fourth temperature threshold, and

wherein the difference between the first and second temperature thresholds is greater than the difference between the third and fourth temperature thresholds.

16. The system of claim 5, wherein the logic is configured to define a schedule of expected usage for the temperature control element based on the data, the schedule having predefined time slots, and wherein the logic is configured to classify the time slots based on the data.

17. The system of claim 16, wherein the logic is configured to determine whether one of the time slots has been misclassified based on the activation states monitored by the logic during one of the occurrences of the reoccurring time period corresponding to the one time slot, and wherein the logic is configured to change a classification of the one time slot based on a determination that the one time slot has been misclassified.

9. A method comprising the steps of:

selectively activating a temperature control element to maintain a temperature of a liquid within a tank within a first desired temperature range during one of a first plurality of time periods;

determining the amount of time that the temperature control element is activated during the one of the first plurality of time periods;

automatically selecting a second temperature range based on the amount of time that temperature control element is determined to be activated during the one of the first plurality of time periods;

measuring a temperature of the liquid during a subsequent time period corresponding to the one of the first plurality of time periods;

comparing a value indicative of the measured temperature to the second temperature range; and

selectively activating the temperature control element to maintain the temperature of the liquid within the second temperature range during the subsequent time period.

10. The method of claim 9, further comprising the steps of:

automatically defining data indicative of a usage history of the temperature control element based on the determined amount of time that the temperature control element is activated during each of the first plurality of time periods; and

automatically selecting different temperature ranges for the temperature control element based on the data.

11. The method of claim 9, further comprising the steps of:

defining a schedule based on the determined amount of time that the temperature control element is activated during each of the first plurality of time periods, the schedule having a plurality of time slots each corresponding to a different time period of the first plurality of time periods; and

automatically associating each of the time slots in the schedule with a respective temperature range.

12. A method, comprising the steps of:

detecting changes in temperature of a liquid within a tank over time;

activating a temperature control element based on the changes in temperature;

tracking activation states of the temperature control element;

defining a schedule of classified time slots, each of the time slots classified based on an amount of time that the temperature control element is determined to be activated, based on the tracking step, during a time period corresponding to the respective time slot;

automatically selecting a temperature threshold based on the schedule of the classified time slots; and

controlling the temperature control element based on the selected temperature threshold.

13. The method of claim 12, further comprising the steps of:

associating a time period with one of the classified time slots;

selecting, for the associated time period, a temperature threshold based on a total amount of time that the temperature control element is determined, based on the tracking step, to be activated for the one classified time slot;

comparing a sensed temperature to the threshold selected during the time period; and

controlling the temperature control element based on the comparing step.

18. The method of claim 12, further comprising the steps of:

classifying one of the time slots based on the tracking step for activation states occurring during a first time period corresponding to the one time slot;

selecting a temperature threshold for controlling the temperature control element during a second time period corresponding to the one time slot;

determining whether the one time slot has been misclassified based on the tracking step for activation states occurring during the second time period; and

updating a classification for the one time slot based on the determining step.