Monitoring and recoverable protection of thermostat switching circuitry

• US 8,659,302 B1
• Filed: 09/21/2012
• Issued: 02/25/2014
• Est. Priority Date: 09/21/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Nest Labs Incorporated (Alphabet Inc.)
• Inventors: Warren, Daniel Adam, Conner, Brian J., Smith, Ian C.
• Primary Examiner(s): Valone, Thomas F
• Application Number:
  US13/624,882
• Time in Patent Office: 522 Days
• Field of Search: 324/550
• US Class Current: 324/550
• CPC Class Codes: F24D 5/02 operating with discharge of hot air into the space or area to be heated
• CPC Class Codes: F24D 5/12 using heat pumps
• CPC Class Codes: G01R 31/74 Testing of fuses
• 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: H01H 2300/03 Application domotique, e.g. for house automation, bus connected switches, sensors, loads or intelligent wiring
• CPC Class Codes: H01H 85/0241 Structural association of a fuse and another component or apparatus switches with built-in fuses H01H9/10, spark-gap arresters H01H85/44, transformers and inductances H01F27/402, capacitors H01G2/14, lamps H01K1/66, semiconductors H01L23/5256 or H01L23/62
• CPC Class Codes: H01H 85/32 Indicating lamp structurally associated with the protective device
• CPC Class Codes: H02H 7/20 for electronic equipment for converters H02H7/10; for electric measuring instruments G01R1/36; for dc voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08
• CPC Class Codes: H05B 1/0205 using a fusible material
• CPC Class Codes: Y02B 30/13 Hot air central heating systems using heat pumps
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/14 Protecting elements, switches, relays or circuit breakers

Abstract

Voltage is detected on both sides of a protection fuse within a thermostat, such that a determination can be made as to the status of the fuse. When a blown fuse is detected, the user can be notified via (1) an error message on the thermostat display, and/or (2) a message on another device such as a mobile device and/or web-client device. According to some embodiments the thermostat manufacturer is notified via network connection. According to some embodiments drain voltage is measured on MOSFETs used in the thermostat for switching on and off HVAC functions. If an over-current is detected on a FET switch, it immediately turned off and a fault indictor is sent to the microcontroller. The FET switch remains “off” until it is re-enabled under control of the microcontroller.

Claims

1. A method of automated monitoring of a protection fuse within a thermostat, the method comprising:

measuring electrical properties associated with first and second terminals of the protection fuse, wherein the protection fuse is connected to an HVAC function control circuit configured to turn on and off an HVAC function such that the protection fuse blows when the HVAC function control circuit experiences excessive current;

automatically detecting with a microprocessor within the thermostat whether the fuse is in a blown state based on the measured electrical properties; and

in cases where the microprocessor detects the fuse in a blown state;

writing data to a memory indicating the detected blown state of the fuse;

determining whether the thermostat can be operated by re-purposing one or more thermostat components; and

in cases where it is determined that the thermostat can be so operated, re-purposing the one or more thermostat components.

2. A method according to claim 1 wherein the measured electrical properties are voltages at said first and second terminals.

3. A method according to claim 2 wherein the voltages at said first and second terminals are measured through first and second voltage dividers respectively using an analog to digital converter on the microprocessor.

4. A method according to claim 1 further comprising in cases where the microprocessor detects the fuse in a blown state, displaying an error message on a display of the thermostat indicating that the fuse is blown.

5. A method according to claim 1 further comprising in cases where the microprocessor detects the fuse in a blown state, causing a message to be transmitted to a user indicating that the fuse is blown.

6. A method according to claim 5 wherein the message is transmitted to a web application for viewing by a user on a personal computer.

7. A method according to claim 5 wherein the message is transmitted to a smart phone.

8. A method according to claim 1 further comprising in cases where the microprocessor detects the fuse in a blown state, causing information to be transmitted to a manufacturer of the thermostat indicating that the fuse is blown.

9. A method according to claim 8 wherein the information transmitted to the manufacturer includes diagnostic information which facilitates a diagnosis performed by the manufacturer of potential problems associated with the thermostat.

10. A method according to claim 9 further comprising displaying a message offering expert assistance to a user of the thermostat based in part on the diagnosis performed by the manufacturer of potential problems associated with the thermostat.

11. A method according to claim 1 further comprising in cases where the microprocessor detects the fuse in a blown state:

storing information indicating settings associated with the thermostat on a memory remote from the thermostat; and

shutting down the thermostat.

12. A method according to claim 1 further comprising:

notifying the user of the re-purposing of the one or more thermostat components; and

guiding the user to make one or more wiring modifications.

13. A method according to claim 1 wherein the re-purposing one or more thermostat components includes altering the purpose of one or more wire connection terminals on the thermostat.

14. A method of automated sensing of an anomalous wiring condition associated with a thermostat, the method comprising:

switching on a field effect transistor within the thermostat, the field effect transistor and associated circuitry configured to turn on an HVAC function;

monitoring one or more electrical properties associated with the field effect transistor;

determining if an anomalous wiring condition is associated with the field effect transistor based at least in part on the monitored one or more electrical properties; and

in cases where it is determined that an anomalous wiring condition is associated with the field effect transistor;

switching off the field effect transistor;

determining whether the thermostat can be operated by re-purposing one or more thermostat components; and

in cases where it is determined that the thermostat can be so operated, re-purposing the one or more thermostat components.

15. A method according to claim 14 wherein the anomalous wiring condition causes excessive current through the field effect transistor.

16. A method according to claim 14 wherein the monitored one or more electrical properties includes monitoring a voltage level of a node associated with a drain of the field effect transistor.

17. A method according to claim 14 further comprising:

determining if the anomalous wiring condition has been corrected; and

subsequent to the determination of the correction, switching on the field effect transistor.

18. A method according to claim 14 wherein the circuitry configured to turn on the HVAC function includes a second field effect transistor that is switched on and off along with the field effect transistor.

19. A method according to claim 14 further comprising when it is determined that an anomalous wiring condition is associated with the field effect transistor, displaying an error message on a display of the thermostat indicating the anomalous wiring condition.

20. A method according to claim 14 further comprising when it is determined that an anomalous wiring condition is associated with the field effect transistor, causing a message to be transmitted to a user indicating the anomalous wiring condition, the message being transmitted using technology of a type selected from a group consisting of transmission to a web application for viewing on a computer, transmission to a mobile application for viewing on a smart phone, and transmission to a mobile application for viewing on a tablet computer.

21. A method according to claim 14 further comprising when it is determined that an anomalous wiring condition is associated with the field effect transistor, causing information to be transmitted to a manufacturer of the thermostat indicating the anomalous wiring condition.

22. A method according to claim 21 wherein the information transmitted to the manufacturer includes diagnostic information from which facilitates a diagnosis performed by the manufacturer of potential problems associated with the thermostat.

23. A method according to claim 21 further comprising offering expert assistance to a user of the thermostat based in part on the diagnosis performed by the manufacturer of potential problems associated with the thermostat.

24. A method of automated monitoring of a protection fuse within a thermostat, the method comprising:

measuring voltages associated with first and second terminals of the protection fuse, wherein the protection fuse is connected to an HVAC function control circuit configured to turn on and off an HVAC function such that the protection fuse blows when the HVAC function control circuit experiences excessive current;

automatically detecting with a microprocessor within the thermostat whether the fuse is in a blown state based on the measured electrical properties; and

in cases where the microprocessor detects the fuse in a blown state;

writing data to a memory indicating the detected blown state of the fuse;

determining whether the thermostat can be operated by re-purposing one or more thermostat components;

in cases where it is determined that the thermostat can be so operated, re-purposing the one or more thermostat components;

displaying an error message on a display of the thermostat indicating that the fuse is blown;

causing information to be transmitted to a manufacturer of the thermostat indicating that the fuse is blown, the information facilitating a diagnosis performed by the manufacturer of potential problems associated with the thermostat; and

displaying a message offering assistance to a user of the thermostat based in part on the diagnosis performed by the manufacturer of potential problems associated with the thermostat.