Aircraft pitot-static tube with ice detection

• US 8,060,334 B1
• Filed: 09/03/2010
• Issued: 11/15/2011
• Est. Priority Date: 09/03/2010
• Status: Active Grant

• Current Assignee: Philip Onni Jarvinen
• Original Assignee: Philip Onni Jarvinen
• Inventors: Jarvinen, Philip Onni
• Primary Examiner(s): KUNDU, SUJOY K
• Application Number:
  US12/807,428
• Time in Patent Office: 438 Days
• Field of Search: 702/3, 702/24, 702/54, 702/57, 702/58, 702/59, 702/75, 702/130, 702/136, 73/240.1, 73/240.4, 731/702.6, 340/582, 340/962
• US Class Current: 702/136
• CPC Class Codes: B64D 15/12 by electric heating electric heating elements in general H05B
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing
• CPC Class Codes: G01P 5/165 Arrangements or constructions of Pitot tubes

Abstract

An aircraft Ice Detection pitot-static tube is described which uses sensors integrated into the pitot-static tube to determine when and where the pitot-static tube is icing up. Temperature, thermal conductivity and impedance sensor measurements are combined with a mathematical transfer of the impedance sensor output into the complex dielectric plane to identify that the material accreating on the exterior and interior of the pitot-static tube is ice and only ice. Identification of ice realized when the trace in complex dielectric space has a distinctive semi-circular form, which only ice exhibits, with measured values in agreement with reference laboratory data stored in the onboard computer system.

Claims

1. A machine named an Aircraft Pitot-Static Tube with Ice Detection comprising:

means to identify that the temperature of the entire body of the Aircraft Pitot-Static Tube with Ice Detection is below 32 degrees Fahrenheit (0 degrees Centigrade) to assure that frozen conditions of the Aircraft Pitot-Static Tube with Ice Detection are present and ice accreation is possible by the addition of temperature sensors to the Aircraft Pitot-Static Tube with Ice Detection;

means to measure the thermal conductivity of materials accreated on the exterior and partially or totally filling the interior of the Aircraft Pitot-Static Tube With Ice Detection by the addition of thermal conductivity sensors to the Aircraft Pitot-Static Tube With Ice Detection;

means to use the thermal conductivity values measured by the thermal conductivity sensors to differentiate between ice, sleet, frost, deicer fluid, rain water and snow through comparison with reference laboratory measured data;

means to identify when icing, sleeting, deposition of frost and buildup of snow on and in the Aircraft Pitot-Static Tube with Ice Detection is initially occurring by the addition of thermal conductivity sensors to the Aircraft Pitot-Static Tube with Ice Detection;

means to identify the history of icing, sleeting, deposition of frost and buildup of snow accreated on the exterior of Aircraft Pitot-Static Tube with Ice Detection and within its inlet tube and within its inner chamber by the addition of thermal conductivity and impedance sensors to Aircraft Pitot-Static Tube with Ice Detection;

means to measure the variation with frequency of the electrical impedance of materials accreated on the exterior and partially or totally filling the interior of Aircraft Pitot-Static Tube with Ice Detection by the addition of impedance sensors to the Aircraft Pitot-Static Tube with Ice Detection;

means to make three measurements on the exterior surface and interior surfaces of Aircraft Pitot-Static Tube with Ice Detection using sensors that measure temperature, thermal conductivity and electrical impedance of materials, including ice, sleet, frost or snow, that are accreated on the exterior of and partially or totally filling the interior of Aircraft Pitot-Static Tube with Ice Detection;

means to transform electrical impedance data, measured on materials accreated on the exterior of and partially or totally filling the Aircraft Pitot-Static Tube with Ice Detection, into the complex dielectric plane which takes into account the relative geometry and distances between any two electrodes;

means to make a determination whether the transformed impedance data does or does not exhibit a semicircular signature in the complex dielectric plane;

the presence of a distinct semicircular signature absolutely identifying the material under test as ice and only ice;

no other of the possible materials exhibiting such a distinctive signature;

means to measure the thickness and extent of any icing accreated on the exterior of the Aircraft Pitot-Static Tube with Ice Detection and within its inlet tube and within its inner chamber based on measured complex dielectric values and features of the trace in the complex dielectric plane;

means to use the complex dielectric data to identify when Aircraft Pitot-Static Tube with Ice Detection is sufficiently fouled with ice, sleet, frost, deicer fluid, rain water and snow deposits on its exterior surface and inner tube and inner chamber that Aircraft Pitot-Static Tube with Ice Detection can not possibly operate properly;

means to notify the pilots of the aircraft and aircraft control and safety systems that sufficient icing has occurred on a particular Aircraft Pitot-Static Tube with Ice Detection to render it inoperative and eliminate it from further consideration by the pilots as well as by the aircraft'"'"'s control and safety systems.

2. The Aircraft Pitot-Static Tube with Ice Detection recited in claim 1 further comprising a means to identify that the electric heater portion of the Aircraft Pitot-Static Tube with Ice Detection is operating properly and is maintaining the body of the Aircraft Pitot-Static Tube with Ice Detection at temperatures sufficiently above 32 Fahrenheit (0 degrees Centigrade) so that accumulation of ice, sleet, frost and snow on the Aircraft Pitot-Static Tube with Ice Detection is not possible by the addition of temperature sensors to the Aircraft Pitot-Static Tube with Ice Detection.

3. Apparatus for the detection of icing on and in an aircraft pitot-static tube consisting of an Aircraft Pitot-Static Tube with Ice Detection equipped with sensors, the sensors on the Aircraft Pitot-Static Tube with Ice Detection connected electrically to an electronics box located inside the aircraft which houses a computer system with stored reference laboratory data and real time data storage devices, the electronic box output connected electrically to a cockpit display device and to aircraft control and safety systems, the cockpit display unit providing audio and visual warnings that icing of a particular Aircraft Pitot-Static Tube with Ice Detection is beginning when icing of the pitot-static tube is detected, the Aircraft Pitot-Static Tube with Ice Detection system continuing to provide data about the thicknesses and locations of the ice on the exterior and interior of the Aircraft Pitot-Static Tube with Ice Detection after initial detection of icing occurs, comprising:

three types of sensors incorporated at several locations in and on the Aircraft Pitot-Static Tube with Ice Detection;

temperature, thermal conductivity and impedance measuring sensors;

temperature sensors including thermocouple and thermistors on the surfaces of the Aircraft Pitot-Static Tube with Ice Detection and embedded in it;

thermal conductivity sensors including surface mounted thermistor pairs which employ the self heated approach to measure thermal conductivity of materials accreated and deposited over them including ice, sleet, frost, deicer fluid, rain water and snow;

impedance sensor electrodes in the form of continuous annular rings, segmented angular rings, and planar electrodes;

the annular rings placed flush on the outside surface of the barrel of the pitot-static tube and inside on the wall of the inner inlet tube and the planar electrodes facing each other from opposite walls of the inner chamber;

the contents of the electronic box including a system controller, multiplexer, processor, computer system, data storage devices, software, impedance measuring electronic chips, heater and communication unit;

the electronic box connected electrically to the Aircraft Pitot-Static Tube with Ice Detection sensors and in turn to a display unit in the cockpit as well as to aircraft control and safety systems;

a computer system which compares in-flight measured thermal conductivity values with reference laboratory data stored in the computer system and decides based on that comparison the type of accreated material present;

ice, sleet, frost, deicer fluid, rain water or snow;

a display unit in the cockpit which provides a warning to the pilots in the form of an audio alert, flashing light and visual display so notifying the pilots of the initiation of icing, the status with time of icing on each of the redundant Aircraft Pitot-Static Tubes with Ice Detection and a pictorial display of the extent of icing on each Aircraft Pitot-Static Tube with Ice Detection.

4. Apparatus for the detection of icing on and in an aircraft pitot-static tube recited in claim 3 further comprising:

the Aircraft Pitot-Static Tube with Ice Detection mounted fixed to the exterior of the aircraft or mounted on a vane that pivots with respect to the aircraft to keep the Aircraft Pitot-Static Tube with Ice Detection aimed into the oncoming airflow.

5. Apparatus for the detection of icing on and in the Aircraft Pitot-Static Tube with Ice Detection recited in claim 3 further comprising:

thermal conductivity sensors that include two different classes of thermal conductivity sensors other than self heated thermistors to measure thermal conductivity;

sensors that utilize existing steady state and non-steady state methods of measurement.

6. Apparatus for the detection of icing on and in the Aircraft Pitot-Static Tube with Ice Detection recited in claim 3 further comprising:

software in the computer system in the electronics box controlling the selection of impedance sensor pairs of annular rings, annular ring segments and planar electrodes used to conduct the impedance measurements.

7. Apparatus for the detection of icing on and in the Aircraft Pitot-Static Tube with Ice Detection recited in claim 3 further comprising:

apparatus where the body of the Aircraft Pitot-Static Tube with Ice Detection is formed from highly conducting electrical or poorly conducting electrical metals or composite materials where for the case of highly conducting electrical material, the impedance sensors are mounted on top of electrically insulating materials.

8. Apparatus for the detection of icing on and in the Aircraft Pitot-Static Tube with Ice Detection recited in claim 3 further comprising:

the wiring of each sensor electrode to the computer system and data storage devices in the electronic box.

9. Apparatus for the detection of icing on and in the Aircraft Pitot-Static Tube with Ice Detection recited in claim 3 further comprising:

apparatus where in the electronic box are located impedance measuring chips which electrically excite the impedance sensors for measurements of the variation of impedance as a function of excitation frequency.

10. An Aircraft Pitot-Static Tube with Ice Detection system that combines three measurements:

temperature of the pitot-static tube, thermal conductivity of material deposited on and in the pitot-static tube and electrical impedance measurements of material deposits on and in the pitot-static tube, to determine whether the deposited material is ice, sleet, frost, deicer fluid, rain water or snow or other material and from the impedance measurements, through the application of a mathematical transform of the impedance data into the complex dielectric plane, establishing absolutely that the material under test is ice based on a distinctive semi-circular shaped signature only exhibited by ice in the complex dielectric plane; and

comprising;

a system which employs sensors mounted on the exterior and interior surfaces of a pitot-static tube to form an Aircraft Pitot-Static Tube with Ice Detection;

a system that determines where ice is forming on a Aircraft Pitot-Static Tube with Ice Detection and provides as a function of time the physical thickness of the ice that has formed;

a system that ranks the operability of each Aircraft Pitot-Static Tube with Ice Detection being used when icing is occurring and sends a signal to the pilots and to the aircraft'"'"'s control and safety systems when icing has rendered aircraft velocity measurements by that particular Aircraft Pitot-Static Tube with Ice Detection no longer valid and further bans that Aircraft Pitot-Static Tube with Ice Detection from use for any future purpose, until rejuvenated by application of heat;

a system that makes known to the pilots of the aircraft and to the aircraft'"'"'s control and safety systems that a Aircraft Pitot-Static Tube with Ice Detection is no longer a viable instrument to be trusted and drops it from further consideration, until rejuvenated by the application of heat;

a system that makes known to the pilots of the aircraft by both spoken word, flashing light and pictorial display as to what part of the Aircraft Pitot-Static Tube with Ice Detection is being or has been compromised;

ice on the exterior of the Aircraft Pitot-Static Tube with Ice Detection closing off the inlet to the pitot-static tube or internally, ice closing off the inner tube or filling the inner chamber;

each of these possibilities rendering the output of that particular Aircraft Pitot-Static Tube with Ice Detection invalid;

a system that combines three measurements;

temperature, thermal conductivity and electrical impedance measurements with a mathematical evaluation of the impedance data to decide what type of contaminant is forming on or in the Aircraft Pitot-Static Tube with Ice Detection and whether the contaminant is ice, sleet, frost, deicer fluid, rain water or snow;

a system that employs an instrumented Aircraft Pitot-Static Tube with Ice Detection mounted on the outside surface of the aircraft with attached sensors, each of which are connected to equipment in the electronics box, the electronic box mounted internal to the aircrafts exterior surface, data from the sensors used in real time to assess the existence of icing of a particular Aircraft Pitot-Static Tube with Ice Detection, and a system which also stores the sensor data in real time in data storage devices in the electronic box to allow further analysis of the data after the aircraft'"'"'s flight has been completed;

a system that analyzes sensor data in real time by means of the computer system contained in the electronic box in the following manner;

(a) checks the temperature sensor data measured in the body of the Aircraft Pitot-StaticTube with Ice Detection to confirm that the body of the sensor is everywhere below freezing and ice accreation is possible,

(b) compares measured values of thermal conductivity with reference laboratory measured values at the same temperature, which are stored in the computer system, to evaluate the possibility that ice or other substance is present on and in the Aircraft Pitot-Static Tube with Ice Detection,

(c) converts the measured impedance data into complex dielectric plane values taking into account the geometry between impedance sensors,

(d) compares the complex dielectric values and the shape of the complex dielectric trace, derived from the real time impedance measurements, against reference laboratory measured data stored in the onboard computer system to absolutely confirm or reject that the test data being studied is for ice and no other substance;

correct values for the intercepts of the trace with the ordinary relative permittivity axis and a distinctive semicircular shaped trace confirming ice and only ice.