Control system for efficient intermittent operation of building HVAC equipment

• US 4,475,685 A
• Filed: 03/07/1983
• Issued: 10/09/1984
• Est. Priority Date: 03/07/1983
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Grimado, Philip B., Holt, Vernon E., Osifchin, Nicholas
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US06/472,935
• Time in Patent Office: 582 Days
• Field of Search: 236/46 R, 236/47, 165/12, 62/231, 374/170, 374/171, 364/148, 364/557, 364/505, 364/500
• US Class Current: 236/46.00R
• CPC Class Codes: F23N 5/203 using electronic means

Abstract

A system of determining optimum start/stop times for HVAC equipment in a building utilizes quantized inside and outside air temperature values as the controlling data input. Lead-times necessary to achieve the desired control temperatures, given input and output temperature levels are stored in a matrix in a central processor storage. System performance is monitored and results are used to modify the lead-times so that the operating system can more closely achieve the desired results.

Claims

1. A method of determining optimum start/stop times for an air handling unit in order to achieve a predetermined limit temperature within a building space controlled by the air handling unit at some preassigned time comprising the steps of:

sensing an outside temperature outside a building encompassing the building space from an outside array of binary temperature sensors covering a range of outside temperatures and resolving it into quantum levels and assigning a unique integer J to a particular quantum level of the outside temperature sensed

sensing an inside building space temperature within the building space controlled by the air handling unit from an inside array of binary temperature sensors covering a range of inside temperatures and resolving it into quantum levels and assigning a unique integer I to a particular quantum level of the inside building space temperature sensed

storing in a memory an array of start/stop parameter elements having a dimensionality of lead-time and having an individual parameter element associated with each pair of unique integers I and J assigned to the quantum levels of inside and outside air temperature

determining a time interval required to achieve the predetermined limit temperature by activating/deactivating an air handling unit by accessing a start/stop parameter element associated with an integer pair of integer I representing the present building space air temperature quantum level and integer J representing the present quantum level of outside air temperature, and

computing if a time interval between present time and preassigned time equals the time interval to achieve the predetermined limit temperature and activating/deactivating the air handling unit when they are substantially equal.

2. A method of determining optimum start/stop times for an air handling unit as defined in claim 1 where the method of determining a time interval further includes the steps of;

determining if the time interval determined is less than a time interval for a high value of J previously derived and greater than a time interval for a lower value of J previously determined, and replacing the time interval determined by one of these two values if its value is outside these limits.

3. A method of determining optimum start/stop times for an air handling unit as defined in claim 1 and further including the steps of

recording an actual time when an air handling unit is activated/deactivated

interrogating the inside array of binary temperature sensors at a time the air handling unit is activated/deactivated and recording an integer I associated with a quantum level of that temperature

interrogating the outside array of binary temperature sensors at a time the air handling unit is activated/deactivated and recording an integer J associated with a quantum level of that temperature

storing these I and J values recorded at the time of activation/deactivation in memory and computing a time interval between actual time predetermined limit temperature is attained and time of activation/deactivation between a present space air temperature and a building space air temperature at time of activation/deactivation, and

replacing the start/stop parameter element used previously to compute the time interval required to achieve the predetermined limit temperature with the new start/stop parameter element associated with a same quantum level of building space and outside air temperatures.

4. A method of determining optimum start/stop times for an air handling unit as defined in claim 3 and further including the steps of

interrogating if the air handling unit has been activated/deactivated upon reaching the preassigned time and activating/deactivating it if it was not previously activated/deactivated.

5. A method of determining optimum start/stop times for an air handling unit as defined in claim 4 and further including the steps of

periodically checking actual times with selected preassigned times to determine if an air handling unit should be activated and to determine if an air handling unit should be deactivated.

6. A control system for determining optimum start/stop times for an air handling unit in order to achieve a predetermined limit temperature within a building space controlled by the air handling unit at some preassigned time comprising the steps of

first temperature sensing means for sensing an outside temperature outside a building encompassing the space from an outside array of binary temperature sensors covering a range of outside temperatures and resolving it into quantum levels and assigning a unique integer J to a particular quantum level of the outside temperature sensed,

second temperature sensing means for sensing an inside space temperature within the space controlled by the air handling unit from an inside array of binary temperature sensors covering a range of inside temperatures and resolving it into quantum levels and assigning a unique integer I to a particular quantum level of the inside space temperature sensed,

memory means for storing an array of start/stop parameter elements having a dimensionality of lead-time and having an individual parameter element associated with each unique integer I and J assigned to the quantum levels of inside and outside temperature

means for determining a time interval required to achieve the predetermined limit temperature by activating/deactivating an air handling unit by accessing a start/stop parameter element associated with an integer pair of integer I representing the present space air temperature quantum level and integer J representing the quantum level of outside air temperature quantum level, and

means for computing if a time interval between present time and preassigned time equals the time interval to achieve the predetermined limit temperature and switching means for activating/deactivating the air handling unit when they are substantially equal.

7. A control system for determining optimum start/stop times for an air handling unit as defined in claim 6 wherein the control system is adapted for controlling a plurality of air handling units and further including

individual temperature sensing means for sensing air inside space temperatures associated with each individual air handling unit, and

the means for determining including start/stop parameter elements associated with each individual air handling unit.

8. A method of controlling optimum start/stop times for an air handling unit in order to achieve a desired temperature limit in a particular air space at a preassigned time comprising the steps of:

quantizing an outside air temperature into a discrete level identified by an integer J, including the substeps of

presetting an array of binary temperature sensors so that each sensor switches at a different temperature with individual temperature levels distributed over a range of interest,

scanning sensor switch states and associating each combination of switch states with a unique integer J,

quantizing an air space temperature into a discrete level identified by an integer I,

computing a lead-time needed for achieving a desired temperature limit for a preset temperature for different integers I and J,

activating an air handling unit at a preset time when the lead-time represents a time value that added to the present time equals the preassigned time.

10. A method of controlling optimum start/stop times for an air handling unit as defined in claim 8 or 9 wherein the step of computing lead-times comprises the step of;

comparing computed lead-times for specific I,J values with lead-times associated with adjacent I,J values and considering lead-times associated with adjacent I,J values to be limit values for limiting the values of the computed lead-times.

11. A method of controlling optimum start/stop times for an air handling unit as defined in claim 8 or 9 wherein the step of computing a lead-time comprises the steps of;

assigning specific lead-times to specific combinations of the integers I and J and arranging in a tabular form

comparing specific lead-times with actual time intervals needed to achieve a desired temperature and adjusting lead-times to match actual performance.

9. A method of controlling optimum start/stop times for an air handling unit in order to achieve desired temperature limit in a particular air space at a preassigned time comprising the steps of;

quantizing an outside air temperature into a discrete level identified by an integer J,

quantizing an air space temperature into a discrete level identified by an integer I, including the substeps of

presetting an array of binary temperature sensors so that each sensor switches at a different temperature with individual temperature levels distributed over a range of desired temperatures,

scanning sensor switch states and associating each combination of switch states with a unique integer I,

computing a lead-time needed for achieving a desired temperature limit for a preset temperature for different integers I and J.

activating an air handling unit at a preset time when the lead-time represents a time value that added to the present time equals the preassigned time.

12. A method of controlling optimum start/stop times for an air handling unit in order to achieve a desired temperature limit in a particular air space at a preassigned time comprising the steps of;

measuring an outside air temperature by subdividing a temperature range into a plurality of quantized temperature gradations and assigning a specific integer J to the outside temperature in accord with a temperature gradation in which it is located,

measuring an air space temperature by subdividing a temperature range into a plurality of quantized temperature gradations and assigning a specific integer I to the air space temperature in accord with a temperature gradation in which it is located,

computing a lead-time needed for achieving a desired temperature limit for a preset temperature for different integers I and J,

activating an air handling unit at a preset time when the lead-time represents a time value that added to the present time equals the preassigned time.

13. A method of controlling space air temperatures in a building comprising the steps of;

measuring an outside air temperature outside the building by utilizing a first range of temperature divided into a plurality of quantum levels and converting the outside air temperature into an integer J corresponding to the quantum level of the outside air temperature,

measuring an inside air temperature inside a space to be controlled by utilizing a second range of temperature divided into a plurality of quantum levels and converting the inside air temperature into an integer I corresponding to the quantum level of the inside air temperature,

compiling a table of lead-times for each combination of inside and outside air temperature integers I and J that are necessary for establishing a desired temperature in an air space after activation/deactivation of an air handling unit, and

monitoring results of activation/deactivation of an air handling unit and modifying lead-times in the table to correspond to actual performance times.

14. A method of controlling space air temperatures in a building as defined in claim 13 further comprising the steps of

monitoring real time for determining an appropriate activation/deactivation mode of operation, and

determining if available time to time when desired temperature is to be achieved is adequate.

15. A method of controlling space air temperatures in a building comprising the steps of;

converting an air temperature outside the building to an integer representing a quantum level representing the air temperature,

converting an air temperature inside a space to be controlled to an integer representing a quantum level representing the air temperature,

compiling a table of lead-times for each combination of outside and space air temperature quantum levels for amount of time to establish a desired temperature in an air space activation/deactivation of an air handling unit, and

monitoring results of activation/deactivation of an air handling unit and modifying lead-times in the table to correspond to actual performance times, the step of monitoring including substeps of

establishing a table of time intervals required from activation/deactivation to a desired temperature level, and

comparing time intervals required for a particular combination of outside and inside air temperature quantum levels with adjacent lead-times to determine reasonableness of modified lead-times and substituting a lead-time of adjacent quantum levels if it is not reasonable.