Thermostat battery recharging during HVAC function active and inactive states

• US 8,752,771 B2
• Filed: 02/24/2011
• Issued: 06/17/2014
• Est. Priority Date: 11/19/2010
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Nest Labs Incorporated (Alphabet Inc.)
• Inventors: Warren, Daniel Adam, Fiennes, Hugo, Dutra, Jonathan Alan, Bell, David, Fadell, Anthony Michael, Rogers, Matthew Lee
• Primary Examiner(s): Jules, Frantz
• Assistant Examiner(s): TRPISOVSKY, JOSEPH F
• Application Number:
  US13/034,678
• Publication Number:
  US 20120126019A1
• Time in Patent Office: 1,209 Days
• Field of Search: 236/1.C, 236/94, 700/276
• US Class Current: 236/1.C
• CPC Class Codes: B01D 46/0086 Filter condition indicators
• 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 11/32 Responding to malfunctions or emergencies
• CPC Class Codes: F24F 11/39 Monitoring filter performance
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/47 Responding to energy costs
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/56 Remote control
• CPC Class Codes: F24F 11/58 using Internet communication
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/89 Arrangement or mounting of control or safety devices
• CPC Class Codes: F24F 2110/00 Control inputs relating to air properties
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2120/10 Occupancy
• CPC Class Codes: F24F 2120/20 Feedback from users
• CPC Class Codes: F24F 2130/40 Noise
• CPC Class Codes: F24F 2140/00 Control inputs relating to system states
• CPC Class Codes: F24F 2140/60 : Energy consumption
• CPC Class Codes: G05B 13/0265 : the criterion being a learning criterion
• CPC Class Codes: G05B 15/02 : electric
• CPC Class Codes: G05D 23/19 : characterised by the use of electric means G05D23/1393 takes precedence
• CPC Class Codes: G05D 23/1902 : characterised by the use of a variable reference value
• CPC Class Codes: G05D 23/1917 : using digital means
• CPC Class Codes: H01R 9/2416 : Means for guiding or retaining wires or cables connected to terminal blocks
• CPC Class Codes: H04W 4/70 : Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: Y02B 10/20 : Solar thermal
• CPC Class Codes: Y02B 10/70 : Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
• CPC Class Codes: Y02D 30/70 : in wireless communication networks
• CPC Class Codes: Y10T 29/49826 : Assembling or joining

Abstract

A thermostat and related methods are described for controlling one or more functions, such as heating and cooling in an HVAC. According to some embodiments the thermostat includes a rechargeable battery; charging circuitry adapted and arranged to recharge the battery; and control circuitry adapted and arranged to control the one or more HVAC functions using power from the rechargeable battery. According to some embodiments, the thermostat also includes power harvesting circuitry adapted and arranged to harvest power from the HVAC system in cases where no common wire is available to the thermostat, and to supply power to the charging circuit for recharging the battery.

Claims

1. A thermostat for controlling one or more HVAC functions in an HVAC system the thermostat comprising:

a rechargeable battery;

charging circuitry adapted and arranged to recharge the battery;

power harvesting circuitry adapted and arranged to harvest power from a circuit of an HVAC function during times when the HVAC function is active and during times when the HVAC function is inactive, and to supply power to the charging circuit for recharging the battery, wherein during the times when the HVAC function is active, the power harvesting circuitry repeatedly charges and discharges a capacitive element to store electrical energy for use by the charging circuitry by repeatedly opening and closing a solid-state switching circuit for activating the HVAC function, such that during times when the solid-state switching circuit is closed, the HVAC function continues uninterrupted while simultaneously charging the capacitive element; and

control circuitry adapted and arranged to control the one or more HVAC functions using power from the rechargeable battery.

2. A thermostat according to claim 1 wherein the power harvesting circuitry is adapted and arranged to automatically select harvesting power from a power source among two or more available power sources.

3. A thermostat according to claim 1 wherein during power harvesting from the circuit of the HVAC function during the times when the HVAC function is active, the power harvesting circuitry operates according to the steps of:

monitoring a voltage associated with a charge level of said capacitive element;

instantiating said charging of said capacitive element when said voltage is below a lower threshold; and

terminating said charging of said charging of said capacitive element when said voltage exceeds an upper threshold.

4. A thermostat according to claim 1 wherein the thermostat is adapted to control HVAC systems having more than one power transformer.

5. A thermostat according to claim 1 wherein the charging circuitry is adapted to charge the battery such that longer cycle life is preferred over higher charge capacity.

6. A thermostat according to claim 5 wherein the charging circuitry is adapted to charge the battery to a final float voltage of less than about 4.1V.

7. A thermostat according to claim 6 wherein the charging circuitry is adapted to charge the battery to a final float voltage of between about 3.9V and 4.0V.

16. A thermostat according to claim 1 wherein the HVAC function is heating or cooling.

8. A method for controlling an HVAC system having an HVAC function, the method comprising:

harvesting power from a circuit of an HVAC function during times when the HVAC function is active and during times when the HVAC function is inactive, wherein during the times when the HVAC function is active, the power harvesting circuitry repeatedly charges and discharges a capacitive element to store electrical energy for use by a charging circuitry by repeatedly opening and closing a solid-state switching circuit for activating the HVAC function, such that during times when the solid-state switching circuit is closed, the HVAC function continues uninterrupted while simultaneously charging the capacitive element;

charging a rechargeable battery using the charging circuitry; and

controlling one or more HVAC functions using power from at least the rechargeable battery.

9. A method according to claim 8 wherein the HVAC function is heating or cooling.

10. A method according to claim 8 wherein during power harvesting from the circuit of the HVAC function during the times when the HVAC function is active, the power harvesting circuitry operates according to the steps of:

monitoring a voltage associated with a charge level of said capacitive Element;

instantiating said charging of said capacitive element when said voltage is below a lower threshold; and

terminating said charging of said charging of said capacitive element when said voltage exceeds an upper threshold.

11. A method according to claim 10 wherein the power harvesting circuitry includes solid state switching components and circuitry adapted and arranged to quickly open and close the circuit for controlling the HVAC function.

12. A method according to claim 8 wherein the thermostat is adapted to control HVAC systems having more than one power transformer.

13. A method according to claim 8 wherein the charging circuitry is adapted to charge the battery such that longer cycle life is preferred over higher charge capacity.

14. A method according to claim 13 wherein the charging circuitry is adapted to charge the battery to a final float voltage of less than about 4.1V.

15. A method according to claim 14 wherein the charging circuitry is adapted to charge the battery to a final float voltage of between about 3.9V and 4.0V.