Electronically controlled programmable digital thermostat having variable threshold hysteresis with time

• US 4,388,692 A
• Filed: 09/03/1980
• Issued: 06/14/1983
• Est. Priority Date: 09/03/1980
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Jones, James J., McIntosh, John O.
• Primary Examiner(s): Wise, Edward J.
• Application Number:
  US06/183,703
• Time in Patent Office: 1,014 Days
• Field of Search: 364/557, 364/189, 364/178, 364/139, 364/141, 236/46 R, 165/11-14
• US Class Current: 700/278
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/523 for displaying temperature data
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: G05D 23/1904 variable in time
• CPC Class Codes: G05D 23/20 with sensing elements having variation of electric or magnetic properties with change of temperature G05D23/13 takes precedence

Abstract

An electronic digital programmable wall thermostat system for controlling heating and cooling systems supplying an indoor area or space. The thermostat includes a digital clock, a display for displaying desired parameters of time and temperature and a data entry keyboard for programming the thermostat to maintain desired temperatures during selected time intervals. The heart of the system is a digital processor with memory, which responds to signals from a temperature sensing means which includes an analog to digital converter for controlling the heating and cooling systems in accordance with the sequence programmed therein. An output from the processor gates a triac on and off which in turn activates or deactivates the heating and cooling systems. In a preferred embodiment, a single chip digital processor is used to control the operation of the thermostat system, the keyboard, display and temperature sensing means being selectively scanned from output terminals of the digital processor. The processor is also programmed such that the hysteresis of the thermostat is variable with time in discrete steps. For example, in the heat mode when the triac (heat) is turned on, the hysteresis may be 0.5° F. above the set temperature for a predetermined time period (6 minutes) and then decreased to the set temperature until the triac is turned off. When the triac is turned off, the hysteresis is varied to be 0.5° F. less than the set temperature for 6 minutes and then is increased to the set temperature until the triac is turned back on.

Claims

1. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital circuit means having a plurality of input and output terminals, said digital circuit means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for monitoring said ambient temperature, said digital circuit means including logic circuitry for storing digital coded information entered therein while said information is being processed, said digital circuit means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said discrete steps successively approaching the ambient temperature;

(d) data entry means coupled to said digital circuit means for entering said digital coded information into said digital circuit means;

(e) display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

2. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital circuit means having a plurality of input and output terminals, said digital circuit means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for monitoring said ambient temperature, said digital circuit means including logic circuitry for storing digital coded information entered therein while said information is being processed, said digital circuit means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said logic circuitry produces a threshold hysteresis temperature characteristic which is a first value for a fixed period of time and changes to at least a second value unless the ambient temperature reaches said first value before such change to said second value which activates or deactivates said heating and cooling system causing said threshold hysteresis temperature to change to a first value of opposite polarity around said desired ambient temperature from said first value and remain at said first value of opposite polarity for a fixed period of time and then change to at least a second value of opposite polarity unless the ambient temperature reaches said first value of opposite polarity before such change to said at least second value of opposite polarity which again activates or deactivates said heating and cooling system;

(d) entry means coupled to said digital circuit means for entering said digital coded information into said digital circuit means;

(e) display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

3. A thermostat system according to claim 2 wherein said first temperature value is equal to said first temperature value of opposite polarity.

4. A thermostat system according to claim 3 wherein said equal value is in the range of 0°

to 1°

F.

5. A thermostat system according to claim 2 wherein said fixed period during the cool cycle is different from the fixed period during the heat cycle.

6. A thermostat system according to claim 5 wherein said fixed period during the cool cycle is approximately ten minutes and the fixed period during the heat cycle is approximately six minutes.

7. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital circuit means having a plurality of input and output terminals, said digital circuit means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for monitoring said ambient temperature, said digital circuit means including logic circuitry for storing digital coded information entered therein while said information is being processed, said digital circuit means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said hysteresis temperature varying in a stairstep manner around said desired ambient temperature;

(d) data entry means coupled to said digital circuit means for entering said digital coded information into said digital circuit means;

(e) display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

8. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital circuit means having a plurality of input and output terminals, said digital circuit means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for monitoring said ambient temperature, said digital circuit means including logic circuitry for storing digital coded information entered therein while said information is being processed, said digital circuit means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature and including a second variable threshold hysteresis which varies in discrete steps around said desired ambient temperature and means for selecting either of said variable threshold hysteresis characteristics to control the ambient temperature;

(d) data entry means coupled to said digital circuit means for entering said digital coded information into said digital circuit means;

(e) display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

9. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital processor means having a plurality of input and output terminals, said digital processor means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for continually monitoring said ambient temperature, said digital processor means including a memory for storing digital coded information entered therein while said information is being processed, said digital processor means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with a stored instruction sequence which provides an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said electronic threshold hysteresis characteristic limits the cycling rate of the heating system in the range of five to eight cycles per hour and the cooling system in the range of two to five cycles per hour;

(d) data entry means coupled to said digital processor means for entering said digital coded information into said digital processor means;

(e) digital display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the embient temperature with the electronic threshold hysteresis temperature.

10. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital processor means having a plurality of input and output terminals, said digital processor means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for continually monitoring said ambient temperature, said digital processor means including a memory for storing digital coded information entered therein while said information is being processed, said digital processor means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with a stored instruction sequence which provides an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said discrete steps successively approach the ambient temperature;

(d) data entry means coupled to said digital processor means for entering said digital coded information into said digital processor means;

(e) digital display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

11. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital processor means having a plurality of input and output terminals, said digital processor means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for continually monitoring said ambient temperature, said digital processor means including a memory for storing digital coded information entered therein while said information is being processed, said digital processor means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with a stored instruction sequence which provides an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said memory produces a threshold hysteresis temperature characteristic which is a first value for a fixed period of time and changes to at least a second value unless the ambient temperature reaches said first value before such change to said second value which activates or deactivates said heating and cooling system causing said threshold hysteresis temperature to change to a first value of opposite polarity around said desired ambient temperature from said first value and remain at said first value of opposite polarity for a fixed period of time and then change to at least a second value of opposite polarity unless the ambient temperature reaches said first value of opposite polarity before such change to said at least second value of opposite polarity which again activates or deactivates said heating and cooling system;

(d) data entry means coupled to said digital processor means for entering said digital coded information into said digital processor means;

(e) digital display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

12. A thermostat system according to claim 11 wherein said first temperature value is equal to said first temperature value of opposite polarity.

13. A thermostat system according to claim 12 wherein said equal value is in the range of 0°

to 1°

F.

14. A thermostat system according to claim 11 wherein said fixed period during the cool cycle is different from the fixed period during the heat cycle.

15. A thermostat system according to claim 14 wherein said fixed period during the cool cycle is approximately ten minutes and the fixed period during the heat cycle is approximately six minutes.

16. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital processor means having a plurality of input and output terminals, said digital processor means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for continually monitoring said ambient temperature, said digital processor means including a memory for storing digital coded information entered therein while said information is being processed, said digital processor means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with a stored instruction sequence which provides an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature, said hysteresis temperature varying in a stairstep manner around said desired ambient temperature;

(d) data entry means coupled to said digital processor means for entering said digital coded information into said digital processor means;

(e) digital display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.

17. A thermostat system for controlling heating and cooling systems supplying an indoor area to maintain desired ambient temperatures during selected time periods in said area, said thermostat system comprising;

(a) temperature sensing means including at least one temperature sensor for sensing the ambient temperature of said area and for providing a digital signal indicative thereof;

(b) means for generating time signals;

(c) digital processor means having a plurality of input and output terminals, said digital processor means being coupled to said time signal means and said temperature sensing means for receiving said time signals and for continually monitoring said ambient temperature, said digital processor means including a memory for storing digital coded information entered therein while said information is being processed, said digital processor means being responsive to real time and ambient temperature and to said digital coded information for controlling the heating and cooling systems in accordance with a stored instruction sequence which provides an electronic threshold hysteresis temperature which is variable with time in discrete steps around said desired ambient temperature and including a second variable threshold hysteresis which varies in discrete steps around said desired ambient temperature and means for selecting either of said variable threshold hysteresis characteristics to control the ambient temperature;

(d) data entry means coupled to said digital processor means for entering said digital coded information into said digital processor means;

(e) digital display means for displaying desired parameters of time and temperature including information entered from said data entry means; and

(f) electrically controllable switch means coupled to at least one of said output terminals for selectively activating and deactivating said heating and cooling systems in accordance with a signal from said digital processor means derived from a comparison of the ambient temperature with the electronic threshold hysteresis temperature.