METHODS AND SYSTEMS FOR CONTROLLING VEHICLE DEFROST UNITS

• US 20120047929A1
• Filed: 08/30/2010
• Published: 03/01/2012
• Est. Priority Date: 08/30/2010
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: HAGEN, THOMAS D., DELORME, GILLES M., TUMAS, TODD M.
• Granted Patent: US 8,745,998 B2
• Time in Patent Office: Days
• US Class Current: 62/155
• CPC Class Codes: B60S 1/026 using electrical means

Abstract

Methods and systems are provided for controlling a defrost unit for a vehicle. A prediction is performed as to whether condensation has formed against a surface of the vehicle. The defrost unit is automatically activated when it is predicted that the condensation has formed against the surface. Another prediction is made as to whether condensation has dissipated from the surface while the defrost unit is operating. The defrost unit is automatically deactivated when it is predicted that the condensation has dissipated.

Claims

1. A method for controlling a defrost unit for a vehicle, the method comprising the steps of:

predicting whether condensation has formed against a surface of the vehicle; and

automatically activating the defrost unit when it is predicted that the condensation has formed against the surface.

2. The method of claim 1, further comprising the steps of:

predicting whether the condensation has dissipated; and

automatically deactivating the defrost unit when it is predicted that the condensation has dissipated.

3. The method of claim 1, wherein:

the step of predicting whether the condensation has formed against the surface comprises the steps of;

determining a dew point proximate the vehicle; and

determining a surface temperature proximate the surface; and

the step of automatically activating the defrost unit comprises the step of automatically activating the defrost unit when the surface temperature is less than the dew point.

4. The method of claim 3, wherein the step of determining the dew point comprises the steps of:

determining a humidity proximate the vehicle;

determining an outside air temperature proximate the vehicle; and

calculating the dew point using the humidity and the outside air temperature.

5. The method of claim 3, wherein the defrost unit has an electric grid, and the step of determining the surface temperature comprises the steps of:

determining a resistance of the electric grid; and

estimating the surface temperature using the resistance.

6. The method of claim 5, wherein the step of determining the resistance comprises the steps of:

measuring a voltage of the vehicle;

measuring a current to the electric grid; and

determining the resistance using the voltage and the current.

7. The method of claim 3, wherein:

the defrost unit has an electric grid;

the step of determining the dew point comprises the steps of;

determining a humidity proximate the vehicle;

determining an outside air temperature proximate the vehicle; and

calculating the dew point using the humidity and the outside air temperature; and

the step of determining the surface temperature comprises the steps of;

measuring a voltage of the vehicle;

measuring a current to the electric grid;

determining a resistance of the electric grid using the voltage and the current; and

estimating the surface temperature using the resistance.

8. The method of claim 3, further comprising the step of:

automatically deactivating the defrost unit when the surface temperature exceeds a predetermined value.

9. A method for controlling a defrost unit for a vehicle, the method comprising the steps of:

predicting whether condensation has dissipated from a surface of the vehicle while the defrost unit is operating; and

automatically deactivating the defrost unit when it is predicted that the condensation has dissipated.

10. The method of claim 9, wherein:

the step of predicting whether the condensation has dissipated comprises the step of determining a surface temperature proximate a surface while the defrost unit is operating; and

the step of automatically deactivating the defrost unit comprises the step of automatically deactivating the defrost unit when the surface temperature is greater than a predetermined threshold.

11. The method of claim 10, wherein the defrost unit includes an electric grid, and the step of determining the surface temperature comprises the steps of:

determining a resistance of the electric grid; and

estimating the surface temperature using the resistance.

12. The method of claim 11, wherein the step of determining the resistance comprises the steps of:

measuring a voltage of the vehicle;

measuring a current to the electric grid; and

determining the resistance using the voltage and the current.

13. A system for controlling a defrost unit for a vehicle, the system comprising:

a data unit configured to obtain data regarding a parameter pertaining to the vehicle; and

a processor coupled to the data unit and configured to;

predict, using the data, whether condensation has formed against a surface of the vehicle; and

automatically activate the defrost unit when it is predicted that the condensation has formed against the surface.

14. The system of claim 13, wherein the processor is further configured to:

predict, using the data, whether the condensation has dissipated; and

automatically deactivate the defrost unit when it is predicted that the condensation has dissipated.

15. The system of claim 13, wherein the processor is further configured to:

determine a dew point proximate the vehicle using the data;

determine a surface temperature proximate the surface using the data; and

activate the defrost unit when the surface temperature is less than the dew point.

16. The system of claim 15, wherein:

the data unit comprises;

a first sensor configured to measure a humidity proximate the vehicle; and

a second sensor configured to measure an outside air temperature proximate the vehicle; and

the processor is coupled to the first sensor and the second sensor, and is configured to calculate the dew point using the humidity and the outside air temperature.

17. The system of claim 15, wherein:

the defrost unit has an electric grid;

the data unit comprises;

a first sensor configured to measure a voltage of the vehicle; and

a second sensor configured to measure a current to the electric grid; and

the processor is coupled to the first sensor and the second sensor, and is further configured to;

determine a resistance of the electric grid using the voltage and the current; and

estimate the surface temperature using the resistance.

18. The system of claim 15, wherein:

the defrost unit has an electric grid;

the data unit comprises;

a first sensor configured to measure a humidity proximate the vehicle; and

a second sensor configured to measure an outside air temperature proximate the vehicle;

a third sensor configured to measure a voltage of the vehicle; and

a fourth sensor configured to measure a current to the electric grid; and

the processor is coupled to the first sensor, the second sensor, the third sensor, and the fourth sensor, and is further configured to;

calculate the dew point using the humidity and the outside air temperature;

determine a resistance of the electric grid using the voltage and the current; and

estimate the surface temperature using the resistance.

19. The system of claim 15, wherein the data unit comprises a receiver that is coupled to the processor and configured to receive a value of the dew point, the surface temperature, or both.

20. The system of claim 15, wherein the processor is further configured to deactivate the defrost unit when the surface temperature exceeds a predetermined threshold.