Thermostat incorporating a carbon dioxide sensor suitable for reading using potentiostat techniques, and environmental control system incorporating such thermostat

• US 6,578,770 B1
• Filed: 04/09/2002
• Issued: 06/17/2003
• Est. Priority Date: 04/09/2002
• Status: Expired due to Term

• Current Assignee: Rosen Technologies LLC (IPValuation Partners, LLC)
• Original Assignee: Howard B Rosen
• Inventors: Rosen, Howard B.
• Primary Examiner(s): Esquivel, Denise L.
• Assistant Examiner(s): NORMAN, MARC E
• Application Number:
  US10/119,180
• Time in Patent Office: 434 Days
• Field of Search: 236/49.3, 236/11, 73/310.5, 165/248, 165/249, 454/256, 454/257, 454/258, 454/259, 454/239
• US Class Current: 236/49.3
• 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 11/64 using pre-stored data
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F24F 2110/70 Carbon dioxide
• CPC Class Codes: G01N 33/004 for CO, CO2
• CPC Class Codes: G05D 27/02 characterised by the use of electric means
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A system for monitoring and modifying the quality and temperature of air within a conditioned space includes a blower unit, an optional damper unit for selectively admitting outside air into the conditioned space, a temperature moderating unit and a control unit. The control unit includes a thermostat and conventional temperature control apparatus for selectively activating the temperature moderating unit to maintain the desired temperature in the conditioned space. The control unit also incorporates CO₂ concentration measuring and control apparatus which employs a small CO₂ sensor. The CO₂ sensor includes upper and lower electrodes with an intermediate solid electrolyte. A voltage having a cyclic waveform is applied across the upper and lower electrodes, and the current through the CO₂ sensor is read at at least one predetermined voltage representing a CO₂ peak. The measured current is representative of the CO₂ concentration. CO₂ concentration modifying apparatus is responsive to sensing a first predetermined CO₂ concentration for turning on the blower unit and, optionally, to sensing a second, higher, predetermined CO₂ concentration for actuating the damper unit to admit outside air.

Claims

1. A system for monitoring and modifying the quality and temperature of air within a conditioned space and including a blower unit, a temperature moderating unit and a control unit, said control unit comprising:

A) a thermostat including temperature set point establishment means and temperature control means for selectively activating said temperature moderating unit when the temperature of the conditioned space deviates by a predetermined amount from the established temperature set point; and

B) CO₂ concentration measuring and control apparatus for the conditioned space, said CO₂ concentration measuring and control apparatus comprising;

1) a CO₂ sensor comprising;

a) a reference electrode source of oxygen anions;

b) a lower electrical reference electrode coupled to said reference electrode source of anions;

c) a solid electrolyte coupled to said lower reference electrode;

d) a buffer layer; and

e) an upper electrode coupled to said buffer layer;

2) CO₂ concentration measuring apparatus in which;

a) an electrical voltage is applied between said lower electrical reference electrode and said upper electrical electrode, said electrical voltage having a cyclic waveform and instantaneous values between a predetermined negative voltage and a predetermined positive voltage; and

b) the current through said electrolyte measured, at a predetermined voltage intermediate said predetermined negative voltage and said predetermined positive voltage, is representative of the CO₂ concentration; and

3) CO₂ concentration modifying apparatus responsive to the measurement of at least a first predetermined CO₂ concentration for turning on said blower unit.

2. The system of claim 1 in which said CO₂ sensor is emplaced on a substrate which also carries a heater serving to maintain said CO₂ sensor at a predetermined temperature.

3. The system of claim 2 in which said predetermined temperature falls within the range of 30°

C. and 300°

C.

4. A system for monitoring and modifying the quality and temperature of air within a conditioned space and including a damper unit for selectively admitting outside air into the conditioned space, a temperature moderating unit and a control unit, said control unit comprising:

A) a thermostat including temperature set point establishment means and temperature control means for selectively activating said temperature moderating unit when the temperature of the conditioned space deviates by a predetermined amount from the established temperature set point; and

B) CO₂ concentration measuring and control apparatus for the conditioned space, said CO₂ concentration measuring and control apparatus comprising;

1) a CO₂ sensor comprising;

a) a reference electrode source of oxygen anions;

b) a lower electrical reference electrode coupled to said reference electrode source of anions;

c) a solid electrolyte coupled to said lower reference electrode;

d) a buffer layer; and

e) an upper electrode coupled to said buffer layer;

2) CO₂ concentration measuring apparatus in which;

a) an electrical voltage is applied between said lower electrical reference electrode and said upper electrical electrode, said electrical voltage having a cyclic waveform and instantaneous values between a predetermined negative voltage and a predetermined positive voltage; and

b) the current through said electrolyte measured, at a predetermined voltage intermediate said predetermined negative voltage and said predetermined positive voltage, is representative of the CO₂ concentration; and

3) CO₂ concentration modifying apparatus responsive to the measurement of at least a first predetermined CO₂ concentration for actuating said damper unit to admit outside air into the conditioned space.

5. The system of claim 4 in which said CO₂ sensor is emplaced on a substrate which also carries a heater serving to maintain said CO₂ sensor at a predetermined temperature.

6. The system of claim 5 in which said predetermined temperature falls within the range of 30°

C. and 300°

C.

7. A system for monitoring and modifying the quality and temperature of air within a conditioned space and including a blower unit, a damper unit for selectively admitting outside air into the conditioned space, a temperature moderating unit and a control unit, said control unit comprising:

A) a thermostat including temperature set point establishment means and temperature control means for selectively activating said temperature moderating unit when the temperature of the conditioned space deviates by a predetermined amount from the established temperature set point; and

B) CO₂ concentration measuring and control apparatus for the conditioned space, said CO₂ concentration measuring and control apparatus comprising;

1) a CO₂ sensor comprising;

a) a reference electrode source of oxygen anions;

b) a lower electrical reference electrode coupled to said reference electrode source of anions;

c) a solid electrolyte coupled to said lower reference electrode;

d) a buffer layer; and

e) an upper electrode coupled to said buffer layer;

2) CO₂ concentration measuring apparatus in which;

a) an electrical voltage is applied between said lower electrical reference electrode and said upper electrical electrode, said electrical voltage being a cyclic waveform and instantaneous values between a predetermined negative voltage and a predetermined positive voltage; and

b) the current through said electrolyte, measured at a predetermined voltage intermediate said predetermined negative voltage and said predetermined positive voltage, is representative of the CO₂ concentration; and

3) CO₂ concentration modifying apparatus;

a) being responsive to the measurement of at least a first predetermined CO₂ concentration for turning on said blower unit; and

b) being responsive to the measurement of at least a second predetermined CO₂ concentration, higher than said first predetermined CO₂ concentration, for actuating said damper unit to admit outside air into the conditioned space.

8. The system of claim 7 in which said CO₂ sensor is emplaced on a substrate which also carries a heater serving to maintain said CO₂ sensor at a predetermined temperature.

9. The system of claim 8 in which said predetermined temperature falls within the range of 30°

C. and 300°

C.