Systems And Methods For Windshield Deicing

• US 20120234816A1
• Filed: 10/05/2011
• Published: 09/20/2012
• Est. Priority Date: 02/11/2002
• Status: Active Grant

• Current Assignee: The Trustees of Dartmounth College (Dartmouth College)
• Original Assignee: The Trustees of Dartmounth College (Dartmouth College)
• Inventors: Petrenko, Victor, Sullivan, Charles R., Kozlyuk, Valeri, Nickolayev, Oleg
• Granted Patent: US 8,921,739 B2
• Time in Patent Office: Days
• US Class Current: 219/203
• CPC Class Codes: H05B 1/0236 for vehicles
• CPC Class Codes: H05B 2203/035 Electrical circuits used in resistive heating apparatus
• CPC Class Codes: H05B 3/84 Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields

Abstract

Cost efficient, lightweight and rapid windshield deicing systems and methods are disclosed. The systems utilize step-up converters or inverters, or dual-voltage batteries, to provide a voltage high enough to deice a windshield in less than thirty seconds at ambient temperatures above −10 C. Some of the disclosed systems include sensors for deicing element and ambient temperatures, and in some embodiments windspeed. All embodiments have a controller for limiting deicing time to that sufficient to melt a boundary layer of ice. The controller of embodiments with sensors computes deicing time as a function of ambient temperature. Embodiments interact with wiper systems to enable wipers to clear ice once the boundary layer is melted.

Claims

1. A windshield deicing system, comprising:

a low voltage power source for providing low voltage power;

a step-up subsystem comprising a converter selected from the group consisting of a DC-DC converter, a DC-AC inverter, and a dual-voltage battery, the step-up subsystem configured to transform the low voltage power into high voltage power,

wherein if the step-up converter is a DC-DC converter or a DC-AC inverter, the step-up converter is an intermittent-duty converter;

a controller-timer for enabling the step-up converter for a deicing time determined sufficient to melt a boundary layer of ice, where the boundary layer of ice is between one micron and one millimeter in thickness; and

a windshield heater, the windshield heater being resistively heated at a deicing power level when the converter is enabled and the high voltage power is conducted through the windshield heater.

2. The system of claim 1, wherein the low voltage power source comprises a vehicle battery coupled to a charging system.

3. The system of claim 1 further comprising wipers, and wherein the controller-timer activates the wipers after the deicing time.

4. The system of claim 3 further comprising a separation heater, the controller-timer configured to activate the separation heater prior to activating the windshield heater.

5. The system of claim 3, further comprising apparatus for sensing ground fault currents and for interrupting current to the windshield heater when ground fault currents are detected.

6. The system of claim 3, wherein the system further comprises sensors, and wherein the deicing time is computed from at least an ambient temperature.

7. The system of claim 6 wherein the step-up subsystem is an intermittent-duty converter, and wherein the controller-timer is configured to operate the step-up subsystem to provide power to the windshield heater at a maintenance power level of less than or equal to one fourth of the deicing power level after the deicing time.

8. The system of claim 7 wherein the maintenance power level is determined by feedback from a windshield temperature sensor.

9. The system of claim 7 wherein the maintenance power level is computed from outside ambient temperature and windspeed.

10. The system of claim 6 wherein the sensors further comprise apparatus for determining an ice density, and wherein the deicing time is computed from both an ambient temperature and the ice density.

11. The system of claim 6, wherein the sensors further comprise apparatus for measuring a voltage, and wherein the deicing time is determined from the voltage.

12. The system of claim 6 wherein the step-up subsystem is a dual-voltage battery, and wherein a low-voltage output of the dual-voltage battery provides power to the controller-timer.

13. The system of claim 6, wherein the system further comprises sensors configured to measure a temperature selected from the group consisting of a temperature of the ice-windshield interface and a temperature of the windshield heater, and wherein the deicing time is determined from the selected temperature.

14. The system of claim 13 wherein the step-up subsystem is an intermittent-duty converter, and wherein the controller-timer is configured to operate the step-up subsystem to provide power to the windshield heater at a maintenance level of less than or equal to one fourth of the deicing power level after the deicing time.

15. The system of claim 6 wherein the step-up subsystem is a dual-voltage battery, and wherein the controller-timer is configured to operate the step-up subsystem to provide power to the windshield heater at an average maintenance power level of less than or equal to one fourth of the deicing power level after the deicing time by repeatedly:

placing the dual-voltage battery into a low voltage configuration,

charging the dual-voltage battery,

placing the dual-voltage battery into a high voltage configuration, and

providing deicing power to the windshield heater.

16. The system of claim 1, wherein at least one windshield heater is disposed between a shatter resistant plastic layer and a glass layer.

17. The system of claim 1, wherein the step-up converter provides the windshield heater with a deicing heating power having a power density in a range from five hundred watts per square meter to one hundred kilowatts per square meter.

18. The system of claim 1, wherein the windshield heater is selected from an optically transparent metal film, an optically transparent metal oxide, a composite of metal oxides and an optically transparent and electrically conductive polymer material.

19. A method of deicing a windshield, comprising:

providing a source of low voltage power;

transforming the low voltage power into high voltage power;

measuring an ambient temperature;

determining a deicing time sufficient to melt a boundary layer of ice from at least the ambient temperature; and

providing the high voltage power to a windshield heater for the deicing time to resistively heat the windshield heater and deice a surface of the windshield.

20. The method of claim 19, wherein the step of transforming the low voltage power into high voltage power comprises charging a dual-voltage battery in low voltage configuration, and switching the dual-voltage battery into a high-voltage configuration.

21. The method of claim 19, wherein the step of transforming the low voltage power into high voltage power comprises utilizing a step-up converter selected from the group consisting of a DC-DC converter and a DC-AC inverter.

22. The method of claim 19, wherein the step of determining a deicing time comprises measuring a density of ice and using the density of ice with the ambient temperature to determine the deicing time.

23. The method of claim 19, wherein the step of determining a deicing time comprises determining an airspeed and using the airspeed with the ambient temperature to determine the deicing time.

24. The method of claim 19 wherein the step of determining a deicing time comprises measuring a voltage during a deicing pulse and using the voltage to determine the deicing time.