AIRCRAFT ICING SENSOR

• US 20090033502A1
• Filed: 08/02/2007
• Published: 02/05/2009
• Est. Priority Date: 08/02/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Gualtieri, Devlin M.
• Granted Patent: US 7,683,791 B2
• Time in Patent Office: Days
• US Class Current: 340/580
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing

Abstract

An apparatus for detecting the presence of ice includes a sensor including a radio-frequency transmission line providing a characteristic impedance, a source coupled to the transmission line and operable to inject a wave into the transmission line, a summer operable to create standing wave, the standing wave including the sum of the injected wave and a reflected wave reflected by the end of the transmission line, the summer being connected between the source and the transmission line, and a detector for detecting the voltage of the standing wave. An embodiment may further include a comparator operable to compare the detected voltage with reference data for determining the presence of ice contacting the sensor.

Claims

1. An apparatus for detecting the presence of ice and comprising:

a sensor operable to be coupled to a surface exposed to moisture and comprising a radio-frequency transmission line providing a characteristic impedance, wherein the transmission line comprises an inner conductor and a first outer conductor proximate to said inner conductor, the first outer conductor being spaced from the inner conductor by dielectric material;

a source coupled to the transmission line and operable to inject a wave into the transmission line;

a summer operable to create a standing wave, the standing wave comprising the sum of the injected wave and a reflected wave reflected by the end of the transmission line, said summer being connected between the source and the transmission line; and

a detector for detecting the voltage of the standing wave.

2. The apparatus of claim 1, further comprising a comparator operable to compare the detected voltage with reference data for determining the presence of ice contacting the sensor.

3. The apparatus of claim 1, wherein the transmission line further comprises a second outer conductor, wherein the inner conductor is disposed between said first and second outer conductors.

4. The apparatus of claim 3, wherein the second outer conductor comprises a permeable screen.

5. The apparatus of claim 1, wherein the summer comprises a “

T”

network including;

a first resistor connected to the output of the source;

a second resistor connected to the detector; and

a third resistor connected to a system ground, and wherein each resistor is coupled to the transmission line.

6. The apparatus of claim 1, further comprising a heating element proximate to said sensor.

7. The apparatus of claim 1, further comprising a current source operable to provide current to said transmission line sufficient to raise the temperature of the transmission line to a predetermined level.

8. The apparatus of claim 6, wherein the wave is injected after raising the temperature of the heating element to a predetermined level.

9. The apparatus of claim 7, wherein the wave is injected after raising the temperature of the transmission line to the predetermined level.

10. A method for detecting the presence of ice on a surface, the method comprising the steps of:

coupling to a portion of the surface a first radio-frequency transmission line;

introducing a radio-frequency voltage into the first transmission line;

detecting a voltage comprising a sum of the introduced radio-frequency voltage and a reflected-wave voltage reflected by the end of the first transmission line; and

comparing the summed voltage with reference data indicating the presence of ice.

11. The method of claim 10, wherein the first transmission line comprises an inner conductor and a first outer conductor proximate to said inner conductor, wherein the first outer conductor is spaced from the inner conductor by dielectric material.

12. The method according to claim 11, wherein the first transmission line further comprises a second outer conductor, wherein the inner conductor is disposed between said first and second outer conductors.

13. The method according to claim 12, wherein the second outer conductor comprises a permeable screen.

14. The method of claim 10, wherein the sum is generated by a “

T”

network including;

a first resistor connected to the output of the source;

a second resistor connected to the detector; and

a third resistor connected to a system ground, and wherein each resistor is coupled to the first transmission line.

15. The method of claim 10, further comprising placing a heating element proximate to said first transmission line.

16. The method of claim 10, further comprising providing current to said first transmission line sufficient to raise the temperature of said first transmission line to a predetermined level.

17. The method of claim 10, further comprising:

placing on a second portion of the surface a second radio-frequency transmission line;

raising the temperature of the second transmission line to a predetermined level;

introducing a second radio-frequency voltage into the second transmission line;

detecting a second voltage comprising a sum of the second introduced radio-frequency voltage and a second reflected-wave voltage reflected by the end of the second transmission line; and

comparing the second summed voltage with the reference data.

18. The method of claim 15, wherein the radio-frequency voltage is introduced after raising the temperature of the heating element to a predetermined level.

19. The method of claim 16, wherein the radio-frequency voltage is introduced after raising the temperature of the first transmission line to the predetermined level.

20. The method of claim 19, further comprising determining a dry condition of the surface based on the comparison.