WO2020155175A1

WO2020155175A1 - Induction heating for pitot tubes and other aircraft air data probes

Info

Publication number: WO2020155175A1
Application number: PCT/CN2019/074689
Authority: WO
Inventors: Shuping Wang
Original assignee: Originex Engineering (Shanghai) Co., Ltd.
Priority date: 2019-02-03
Filing date: 2019-02-03
Publication date: 2020-08-06

Abstract

Air data probes are embedded with one or multiple induction coils. Each coil can be controlled specifically to meet different heating needs at different portion of the probe with different frequencies and/or different current or voltages. Each coil also services as a tool for sensing local temperature inductively, providing essential information for optimum heating process control. Icing condition can be detected by monitoring discontinuity of the mechanical signal the air data probe produces, in conjunction with analyzing the measured probe temperatures.

Description

INDUCTION HEATING FOR PITOT TUBES AND OTHER AIRCRAFT AIR DATA PROBES

TECHNICAL FIELD

This invention relates to aircraft air data probes, for example, pitot tubes. In particular, this invention relates to air data probes with integrated induction heating systems for anti-icing purposes.

BACKGROUND

Icing of the pitot tube and the other air data probes (e.g. the pitot-static port, the static port, the total air temperature probe, and the angle of attack sensor /alpha vane) has long been identified as a severe flight safety hazard that had led to a number of fatal aircraft crashes.

The worst icing condition occurs when aircrafts travel at a high altitude through clouds formed with supercooled water droplets. They can rapidly freeze, adhere, and can accumulate upon impingement of any unprotected surfaces or surfaces where the heating is insufficient. In addition, ice crystals or water droplets can be ingested into the openings of various probes.

One particular example of the air data probe that often suffers from the icing issue is the pitot tube. Many aircrafts rely on pitot tubes to provide total pressure data, which is essential for the airspeed calculation. The pitot tube senses the total pressure of the airflow through a small opening at the tip of the tube. If this opening is blocked, for example, by ice accretion, the airspeed data can be unreliable.

Existing anti-icing solutions present issues. For example, conventional electrical resistance wire cannot achieve the desired local heat flux in order to combat severe icing conditions. Typically, pitot tubes heated with electrical resistance wire require 1-2 minutes to eliminate ice accretion. Loosing reliable air speed data for 1-2 minutes is not acceptable for maintaining a safe aircraft operation.

Besides its maximum heat flux is relatively low (on the order of 10 W/cm2) , electrical resistance wire is fragile and subject to overheating and are sometimes not utilized until flight conditions warrant use. Heat is first generated within the resistance wire, then conducts through protective insulation layers of the wire, and finally to the body of pitot tube. Therefore, the wire itself is always at the highest temperature in the system, hence limiting it heating power. Excellent thermal contact with its immediate surroundings has to be maintained, otherwise, local hot spots and subsequent overheating are inevitable.

Furthermore, conventional pitot tube heating systems lack reliable temperature sensing and control capability. Many existing pitot tube heating systems are based on simple ON-OFF control. It is also not practical to introduce additional temperature sensor into the conical portion of the pitot tube due to the small size of the cone. A lack of reliable and practical temperature measurement of the pitot tube is the reason why a more energy efficient and responsive control algorithm has not been commonly implemented in practice.

Therefore, there is a need for an improved air data probe heating method and design that delivers greater heat flux, is more reliable and controllable than the conventional design with electrical resistance heating systems.

SUMMARY

The approach presented in this application utilizes induction heating technology that overcomes the drawbacks of electrical resistance heating, providing a heating solution for air data probes that can deliver an order of magnitude greater local heat flux, and is non-contact and controllable.

The present invention relates to air data probes embedded with one or multiple induction coils. Each coil can be controlled specifically to meet different heating needs at different portion of the probe with different frequencies and/or different current or voltages. Each coil also services as a tool for sensing local temperature inductively, providing essential information for optimum heating process control. Icing condition can be detected by monitoring discontinuity of the mechanical signal the air data probe produces, in conjunction with analyzing the measured probe temperatures.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, with emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an example system block diagram for an induction heated air data probe system according to aspects of the present application.

FIG. 2A is a drawing of a partial sectional view of an induction heated pitot tube according to aspects of the present application.

FIG. 2B is a drawing of a detailed view of the conical portion and the straight portion of the pitot tube according to aspects of the present application.

FIG. 2C is drawing of a detailed view of the straight portion of the pitot tube showing the drain hole according to aspects of the present application.

FIG. 3 is a perspective view of the induction coils for induction heated pitot tubes according to aspects of the present application.

FIG. 4 is an example flowchart for a control system for an induction heated air data probe according to aspects of the present application.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of an air data probe system 100 in accordance to one embodiment of the present invention. The system 100 can include a power generator 102, an air data probe 104 with integrated induction coil (s) 106, and the aircraft avionics system 108. The arrows between components in the diagram indicate the direction of signal feeds. These signals can be electrical power, control signal, mechanical signal, or any combination of them. The avionics system 108 in this context can include aircraft electronic systems and does not include the associated induction power generators 102. The coil 106 can be of a helical, a single turn, or a pancake configuration. The power generator 102 can include a rectifier, an inverter, a load matching circuit, and control and monitoring circuits. It can convert supply power from the aircraft, for example, 115/220V AC power at 400Hz, to a desired frequency and current/voltage for the induction coil 106 embedded in the probe 104. If the air data probe 104 has more than one induction coil 106, the power generator 102 can supply each induction coil 106 independently with suitable frequency and current/voltage. The respective frequency can be in the range of a few kHz to a few hundred kHz, or higher. In some cases, power supplied to each coil 106 can be of high current and low voltage. The power generator 102 can also provide precise feedback control and inductive temperature sensing, adjusting the heating rate in response to the varying heating loads during different stages of the flight. The mechanical signal generated by the air data probe 104, for instance, the total pressure signal generated by a pitot tube, can be transmitted to the avionics system 108. The power generator 102 can have either one-way or two-way communication to the avionics system 108. The latter mode is shown in FIG. 1. The avionics system 108 can provide information including but not limited to heating ON-OFF commands, heating modes, temperature set points, mechanical quantities measured by the air data probe 104 to the power generator 102, aiding its control of the heating process. The power generator 102 can return measured probe temperature and other relevant operating status back to the avionics system 108 for monitoring and control purposes. In a simpler one-way communication mode, the information of measured probe temperatures and the operating status of the power generator 102 are not sent to the avionics system 108. This information can then be used internally by the power generator 102.

It either mode, the power generator 102 can operate autonomously with limited inputs from the avionics system 108 (for example, only with heating ON-OFF signals, or another set of inputs as discussed) based on pre-programmed logics and its detected temperature and electoral and electromagnetic characteristics of the air data probes 104.

Each power generator 102 can service one or multiple air data probes 104. In another embodiment, multiple power generators 102 can work in parallel in either distributed, central, or a hybrid fashion, servicing multiple number and/or multiple types of probes.

The induction heated air data probe maintains a similar aerodynamic design (size and geometry) compared with conventional air data probe. The mounting interface and the mechanical signal connection can be compatible with existing systems, allowing for an easy retrofitting procedure. The added power generator can be of a compact design and can be installed inside fuselage close to the air data probe.

FIG. 2A is an illustration of a pitot tube 200 as an example embodiment of the present invention. It can include a conical portion 210, a straight portion 220, a transitional portion 230, and a vertical portion 240.

The conical portion 210 has a frontal opening 211. An outer tapered surface 212a of the conical portion 210 can converge or taper from a tip 218 (see FIG. 2B) of the frontal opening 211 to an outer tube 229. An inner tapered surface 212b of the conical portion 210 can converge or taper from a tip 218 towards an inner straight surface 212c of the conical portion 210, which forms the air channel 221, along with the inner air channel tube 228 in the straight portion 220. This air channel 221 extends to the air chamber 231 in transitional portion 230, forming a continuous airway linking the vertical pressure line 241 that ultimately terminates, for example, at a pressure transducer (not shown) , which is part of the avionics system 108. The pitot tube 200 can have one or several drain holes 226 in the straight 220 or the transitional portion 230. The pitot tube can have baffles 225 to prevent ice crystals and water droplets from reaching the air chamber 231 in the transitional portion 230. In other cases, the air channel 221 and the vertical pressure line 241 can be directly connected, sealed from the air chamber 231.

The vertical portion 240 of the pitot tube can provide connection and terminals for the vertical pressure line 241, power cables 245, and a secondary temperature sensor 233. The vertical portion 240 of the pitot tube 200 can also provide a separation from the air plane fuselage so that the air flow experienced by the cone can be absent from the influence of the velocity boundary layer.

The heating demands for different parts of the pitot tube 200 can be vastly different. For example, the convective heat transfer coefficient as well as the probability of ice collection (i.e. ice collection efficiency) on the surfaces (212a, 212b, and 218) of the conical portion 210 can be orders of magnitude greater than those on the external surface 227 of the straight portion 220 because the conical portion 210 is in or adjacent to the stagnation region of the airflow (i.e. the frontal opening 211 and the tip 218) . Moreover, ice accretion blocking the frontal opening 211 can directly affect the reliability of the total pressure signal. While icing on the surfaces of the straight 220, or transitional portion 230, or vertical portion 240 can increase drag, it does not significantly affect the reliability of the signal as long as the drain hole 226 is not blocked. The air channel 221 can be heated to melt and vaporize ingested ice crystal and water droplets and that from condensation. The operational heat flux on the inner air channel tube 228 can be considerably lower than that for the surfaces (212a, 212b, and 218) of the conical portion 210 because the diameter of typical drain holes is small (e.g. around 1 mm) , thereby limiting the convective cooling effect and the amount of ice and water droplets that could be ingested. Nevertheless, the operational total heating power of the conical portion 210 and the straight portion 220 can be comparable due to the fact that the total heat transfer area (internal plus external) of the straight portion 220 is much greater than that for the conical portion 210. Heating to the vertical pressure line 241 and the rest of the transitional portion 230 and vertical portion 240 is mainly to prevent blockage due to water and/or ice formed from condensation, because the baffle 225 can prevent ice crystal and water and supercooled water droplets from reaching the air chamber 231. It is desirable to keep the temperature of the entire air chamber 231 in the transitional portion 230 and the vertical pressure line 241 above zero.

Consequently, to provide heating more effectively to different portions of the pitot tube, multiple coils can be utilized. The achievable maximum heat flux of an induction coil depends on the geometry and the material of the coil and the surrounding part, its operating frequency, current/voltage, among many other factors. Therefore, it is desirable for each coil to be designed specifically and controlled independently with respect to each portion of the pitot tube. For example, as shown in FIG. 2A, the conical portion coil 215 can be a single turn coil, the straight portion coil 223 and the vertical pressure line coil 243 can be multiple-turn helical coils with different number of turns, pitch distances, and coil diameters. For a simpler design, in some cases the straight portion coil 223 and the vertical pressure line coil 243 can be in series connection operating with the same frequency and current.

In some other cases, a hybrid system can be used for a higher heat flux and a quicker response. For example, the conical portion 210 where the required local heat flux is greatest, can be heated with induction coil, whereas other parts of the pitot tube can be heated with electrical resistance wire. The various hybrid systems can include those where any one or more of the induction coils 223 and/or 243 can be replaced with conventional electrical resistance wire winding with small modifications of the overall construction of the pitot tube 200. Also, the conical portion 210 design can be adopted to conventional pitot tube design, adding induction heating capability to the conical portion 210, where ice accretion is most likely.

A secondary temperature sensor 233, for example, a thermocouple, an RTD, or a thermistor, can also be included, providing temperature information for calibration and for backup. In some cases, this secondary temperature sensor 233 can be a resistance heating element, whose electrical resistance changes with temperature. In this way, the secondary temperature sensor 233 can also provide additional heating to the air chamber 231.

FIG. 2B provides a detailed view of the conical portion 210. The conical portion coil 215 can be embedded in the body 214 of the cone 210. It is beneficial to place the coil 215 as close as possible to the tip 218. This conical portion coil 215 can be a single turn coil made from bear solid copper, or solid copper with insulation coating, or Litz wire, or carbon nanowire, or any other coil material suitable for induction heating purposes. It can also be a coil with several turns. The cross-section of the conical portion coil 215 can be square, rectangular, or circular, or other geometry that optimizes the induced eddy current distribution so that the induced magnetic flux is more concentrated towards the tip 218 of the conical portion 210. The body 214 of the conical portion 210 can be made of electrically conductive material with a high relative magnetic permeability, for example, ferritic 430 family stainless steel. It can also be constructed using a base material with additional coating material that has high relatively magnetic permeability applied on either or both internal and external surfaces of the body 214 of the conical portion 210, where heat generation is desired.

Regardless whether the conical portion coil 215 itself comes with electrical insulation or not, additional conical portion insulation 217, which can include ceramic insulation or other material, can be applied between the conical portion coil 215 and the body 214 of the conical portion 210. The conical portion coil 215 can be casted or molded into the insulation material 217. The conical portion insulation material 217 can be machined into a shape that receives a single-turn or multi-turn coil such that it is closely fitted between the conical portion coil 215 and the body 214 of the conical portion. In contrast with electrical resistance wire, a perfect thermal contact between the conical portion coil 215 and the conical portion insulation 217, and between the conical portion insulation 217 and the body 214 is not necessary because heating is achieved in a non-contact fashion via electromagnetic induction. Nonetheless, the thickness of the insulation can be kept reasonably small to provide a close electromagnetic coupling between the conical portion coil 215 and the body 214, while still prevent the conical portion coil 215 from receiving too much heat from the heated body 214.

The part of the conical portion insulation 219 that separates the inner surface of the conical portion coil and body 214 can be the same material and thickness as the rest of the insulation 217. They can be formed together as a single shape. It can be advantageous to use a greater thickness in this part 219 than other parts of the insulation 217 applied over other surfaces (e.g., outer and/or lateral surfaces) of the coil 215. This part of insulation 219 can also include high temperature insulation material like ceramic insulation. The reason for this configuration can be the induced magnetic flux being more concentrated in the inner space of a ring-like coil, for instance, the conical portion coil 215. As a result, the temperature of the inner portion of the body 214 of the conical portion (closer to

surface

212b and 212c) can be at a much higher temperature than other parts of the body 214.

A flux controller 216 can be fitted at the back of the conical portion coil 215, allowing the inducted eddy current to be more concentrated in the forward direction towards the tip 218. The flux controller can be made of formable or machinable material to situate closely to the conical portion coil 215.

FIG. 2B and FIG. 2C each show a part of the straight portion 220 in detail. The straight portion coil 223 can be of helical shape as shown in FIG. 2A. It can be installed in the annulus between the inner air channel tube 228 and the outer tube 229 of the straight portion 220, sandwiched between insulation material 222 and filling material 224. The inner tube 228 and outer tube 229 are simultaneously heated inductively by the straight portion coil 223. They are thermally coupled via conduction in the radical direction through the insulation 222 and filling material 224, and via axial conduction within two concentric tubes (228 and 229) as they join in the conical portion 210.

The straight portion coil 223 can be made of the same material as the conical portion coil 215 or any other coil material suitable for induction heating purposes. It can also come with electrical insulation coating or as bare solid copper with no electrical insulation.

The straight portion insulation material 222 can be of the same material and thickness as that used for the conical portion insulation (217 and/or 219) . In some cases, a more thermally conductive insulation material 222 and a thinner thickness than that used in the conical portion 210 is preferred in order to facilitate the conduction in the radial direction. The reason for this embodiment is because the operational heat flux and temperature of the air channel tube 228 can be lower than that adjacent to the conical portion coil 215.

Filling material 224 can be casted or molded around the straight portion coil 223. It can provide electrical insulation and mechanical support of the coil. It can also be intended to facilitate heat distribution in the straight portion 220. High thermal conductivity electrical insulation material can be utilized. If the straight portion coil 223 itself already has sufficient electrical insulation, a nonmagnetic thermally conductive material can be preferred. This filling material 224 also protects the straight portion coil 223 from moisture and air exposure, improving its longevity.

FIG. 2C illustrates the details of the drain hole 226. A through hole can be fabricated connecting the air channel 221 to surrounding air of the pitot tube 200 through the air channel tube 228, the filling material 224 and insulation material 222, and the outer tube 229. The two-baffle or a multi-baffle system 225 can create an up-and-down flow path within the air channel 221 (see FIG. 2C) , limiting the access of water and ice crystals entering the air chamber 231. The drain hole 226 can be arranged upstream of the baffle 225. Water collected in the bottom of the air channel and the bottom portion of the vertical part of the pitot tube can be expelled through the drain holes 226.

As illustrated in FIG. 3, the conical portion lead 301 of the cone portion coil 215, and the straight portion lead 302 of the straight portion coil 223 can extend through a length of the straight portion within the annulus between air channel tube 228 and outer tube 229. They can connect to feed power cables 245 via soldering/brazing or other secure connection in the transitional portion 230 and/or in the vertical portion 240 of the pitot tube 200. The power cables 245 can terminate at the power generator 102. The power cable 245 can be Litz wire or other appropriate wire. Both leads (301 and 302) can be equipment with magnetic field shields (not shown) to prevent the magnetic field cancelation between that generated by the lead (301 and 302) and that generated by the coils (215 and 223) themselves.

Due to differences in heating demands and coil designs, the conical portion coil 215 can be operating at a higher frequency (on the order of 100 kHz) and a higher current level (e.g. above 50 A) than the straight portion coil 223, which can operate at a frequency on the order of 1 –10 kHz and a current on the order 10 A. For this reason, the conical portion coil 215 can be of a greater cross-sectional area than the straight portion coil 223. Other operational frequencies currents and voltages can be chosen according to specific operational demands and pitot tube 200 design. The maximum heating power for the conical portion coil 215 and straight portion coil 223 can be 100-200 W, respectively. The total heating power the pitot tube can be 200-500 W similar to that in a conventional design heated with electrical resistance wire.

Again, although shown in series with the straight portion coil 223, the vertical pressure line coil 243 can be connected and controlled by the power generator 102 independently in parallel with other coils. The series connection can allow a simpler and a more compact design. In another embodiment of the present invention, a conventional resistive heating coil can be used for the vertical pressure line 241, resulting a hybrid system.

FIG. 4 is an example flowchart 400 for a control system for an induction heated air data probe according to aspects of the present application. The method and procedure outlined in this flowchart 400 can be applied to various air data probes including the pitot tube, the pitot-static tube, the static port, the total temperature probe, and the angle of attack sensor. To better illustrate the principle, some embodiments are provided using the pitot tube 200 illustrated in FIG 2 (A, B, and C) and in FIG. 3.

In box 403, the control system can perform a calibration process for inductive temperature sensing. For example, the inductive temperature sensing techniques can use a calibration process to obtain a reference point or calibration constants. For this reason, a secondary temperature sensor 233 can be placed, for example, in the air chamber 231 of the transitional portion 230 of the pitot tube 200. During the airplane start up process, for example, while the aircraft is stationary or on the ground, the entire pitot tube 200 can be at a uniform temperature. The secondary temperature sensor 233 can measure the same or substantially the same temperature seen by the coils, thereby providing a reference point for calibration.

In box 406, the control system can set threshold temperature levels for portions of the air data probe. For example, each portion can have a target temperature or target temperature range. The conical portion 210, the straight portion 220, and the vertical pressure portion 240 can each be set to a specific predetermined temperature. A PID controller can be implemented for each coil independently to adjust the heating rate to counter the variation of heating loads due to change in the ambient temperature, the air speed and the cloud condition, all of which vary considerably during different stages of the flight. Each coil (215, 223, and 243) can also be controlled to be within its own independent threshold temperature range that can include a maximum temperature threshold limit and a minimum temperature threshold limit.

For the pitot tube 200, the maximum threshold limit (s) can be determined based on materials of the tube (214, 228, 229, and 241) , the flux controller 216, the insulation materials (217, 219 and 222) , the coil (215, 223, and 243) , and the filling material 224, and other considerations, for example, to maintain a maximum temperature point of the pitot tube system below a Curie point of the material or the maximum working temperature of the insulation material. For polymer based material, it can be below 250 ℃. For high temperature ceramic insulation, the maximum is above 1000 ℃. The Curie point of stainless steel 430 can be between 650-750 ℃. Above this point, the magnetic properties change drastically. Therefore, from the control point of view, it can be desirable to keep the maximum temperature in the system (e.g., inner air channel wall adjacent to the conical portion coil near

surfaces

212b and 212c) below the Curie point. From the energy efficiency point view, the coil temperature, which correlates to the temperature the induction coil senses, can also be kept as low as possible for lower electrical resistivity and better induction heating efficiency.

The minimum threshold limit for the conical portion 210 can be determined in order to keep the frontal tip 218 above freezing temperature, or above 0 ℃. Testing can be done, for each particular pitot tube design and conical portion coil design, to determine a threshold temperature that corresponds to 0 ℃ at the frontal tip 218. Likewise, the minimum threshold limit for the straight portion 220 and the vertical portion 240 can be determined in order to keep the external surface 227 and the air channel 221 of the straight portion 220 as well as the vertical pressure line 241 above freezing temperature, or above 0 ℃.

In box 409, the control system can monitor the temperature of the different portions of the air data probe each coil is inductively sensing, as calibrated in box 403. Temperature measurement can be important for the control and operation of the pitot tube. Material properties of the air data probe e.g. electrical resistivity and magnetic permeability can be functions of temperature. Therefore, the electromagnetic characteristics (e.g. equivalent inductance and impedance, power factor, oscillation frequency ... etc. ) of the coil to workpiece (i.e. the pitot tube) coupling varies with temperature. These characteristics and parameters can be tested, measured, and correlated to its temperature.

The algorithm and implementation of such temperature sensing system can depend on the power generator design. One example can include sensing successive zero-crossing points of a half sinusoid of the coil current and generating a temperature-correlated signal based on the interval between these events. This method works for fixed input frequency power generator. Other examples can include a system that measures the impedance of the equivalent circuit via an oscillator, which converts the inductance into a measurable frequency. Another method of temperature measurement can include measuring the resonant frequency of power circuit of an induction system and establishing a relationship between this value and the temperature of the heated part. Accordingly, as an example, with the induction system in place, the temperature of the conical portion 210 of the pitot tube 200 and the straight portion 220 of the pitot tube 200 and other part of the pitot tube can be conveniently sensed by the same induction coil used to deliver the heat.

In box 412, the control system can adjust power of each coil based on measured and target temperatures. For example, the control system can adjust a voltage, current, and/or frequency in order to maintain the target temperatures for each portion of the pitot tube. For example, if a detected temperature is higher than a temperature target for a respective coil, voltage and/or current can be reduced. If detected temperature is lower than a temperature target for a respective coil, voltage and/or current can be increased.

Power can also be adjusted by adjusting frequency, as indicated herein. Frequency can also be varied for induction penetration depth adjustment, efficiency adjustment, and other factors. The temperature of the pitot tube should be maintained above the freeze temperature, while also minimizing the power consumption by tuning and heating power modulation. A PID (proportional integral derivative) control or other feedback control can be utilized in the control system.

Selection of frequency has a profound impact on the efficiency and cost of the induction heating system. Frequency can affect the penetration depth and the coupling efficiency of the system. Moreover, the greater the frequency the higher the cost and complexity of the power supply and modulation system. It is desirable to distribute the heat as uniform as possible in the thickness direction of the pitot tube shell to improve response time and to avoid local hot spot, therefore, a lower frequency may be preferred. On the other hand, a lower frequency could lead to reduced coupling efficiency between the induction coil and the heated part. Also, the required functional number of turns increases with reduced frequency. The optimum frequency that strikes a balance between these several considerations can be selected. It should be noted that as the air data probe heats up, the material properties including electrical resistivity, magnetic permeability, and thermal conductivity of the coil and the heated part of the pitot tube shifts considerably. For this reason, to maintain a constant heating rate or a set surface temperature, the operating frequency may be adjusted from the design value to maintain optimum efficiency. Although some power generator adjusts the supply voltage or current to achieve similar power control.

For the pitot tube 200, the desired penetration depth is similar to that of the thickness of wall of the pitot tube, which is between 0.1-1 mm. Therefore, a frequency can be in the range of 100 Hz to 10 kHz. However, studies can also show due to the small dimension of the conical portion 210, the frequency for the conical portion coil 215 can be on the order of 100 kHz. For the straight portion coil the desired frequency can be on the order of 1 -10 kHz.

In box 415, the control system can determine whether a mechanical signal, for example, the total pressure signal sensed by the pitot tube, the static pressure signal sensed by the static port, the total temperature sensed by a total temperature sensor, is not continuous, or has a discontinuity. For example, if the pressure signal decreases (or increases) faster than a threshold rate that is physically reasonable based on the flight condition, this can be considered a discontinuity. If the temperature measured simultaneously register a decrease of temperature and/or the temperature had dropped below zero, and other parameters are normal (e.g. pitot tube heating ON signal is active) , the control system can determine an icing event had occurred. If such icing event is detected, the control system can proceed to box 418. Otherwise, the control system can proceed to box 409.

In box 418, the heat power is switched to a predetermined maximum setting and the air data probe is allowed to reach their maximum operating temperature until their measured mechanical signal stabilizes. In some cases, this can involve allowing the monitored temperature to exceed its normal operation threshold high range, but does not allow the monitored temperature to exceed an emergency or absolute maximum temperature. Once the mechanical signal stabilizes, or is no longer showing a discontinuity (rate of change is within a threshold) , the control system can proceed to box 409. The control system can also include manual ON and OFF controls that can override the automatic operations discussed above.

Inductive temperature sensing circuitry and control logic module can be incorporated in the power generator unit 102 along with additional temperature sensor inputs, various I/O channel that can communicate to the avionics system 108. The power generator 102 can have programmable PID control capability to adjust the heating power and tuning correction factors to maintain a desired air data probe temperature and heating system efficiency. Additionally, the power generator 102 can be compact, lightweight, robust, and reliable. It can be designed to work with different voltage inputs that vary for different airplanes or easily modified to do so. It can also be capable of operating under -40 ℃ambient temperature. Self-diagnosis functions can be utilized to prevent short-circuit, over-load, and other malfunctions.

The various functions described can be embodied in software or code executed by general purpose hardware as discussed above, as an alternative the same can also be embodied in dedicated hardware or a combination of software/general purpose hardware and dedicated hardware. If embodied in dedicated hardware, each can be implemented as a circuit or state machine that employs any one of or a combination of technologies. These technologies can include discrete logic circuits having logic gates for implementing various logic functions upon an application of one or more data signals, application specific integrated circuits (ASICs) having appropriate logic gates, field-programmable gate arrays (FPGAs) , or other components.

The flowcharts 400 show an example of the functionality and operation of an implementation of portions of components described. If embodied in software, each block can represent a module, segment, or portion of code that can include program instructions to implement the specified logical function (s) . The program instructions can be embodied in the form of source code that can include human-readable statements written in a programming language or machine code that can include numerical instructions recognizable by a suitable execution system such as a processor in a computer system or other system. The machine code can be converted from the source code. If embodied in hardware, each block can represent a circuit or a number of interconnected circuits to implement the specified logical function (s) .

Although the flowcharts 400 show a specific order of execution, it is understood that the order of execution can differ from that which is depicted. For example, the order of execution of two or more blocks can be scrambled relative to the order shown. Also, two or more blocks shown in succession can be executed concurrently or with partial concurrence. Further, in some embodiments, one or more of the blocks shown in the drawings can be skipped or omitted.

Also, any logic or application described that includes software or code can be embodied in any non-transitory computer-readable medium for use by or in connection with an instruction execution system such as a processor in a computer system or other system. In this sense, the logic can include, for example, statements including instructions and declarations that can be fetched from the computer-readable medium and executed by the instruction execution system. In the context of the present disclosure, a "computer-readable medium" can be any medium that can contain, store, or maintain the logic or application described for use by or in connection with the instruction execution system. The computer-readable medium can include any one of many physical media, such as magnetic, optical, or semiconductor media. Examples of a suitable computer-readable medium include solid-state drives or flash memory. Further, any logic or application described can be implemented and structured in a variety of ways. For example, one or more applications can be implemented as modules or components of a single application. Further, one or more applications described can be executed in shared or separate computing devices or a combination thereof. For example, a plurality of the applications described can execute in the same computing device, or in multiple computing devices.

The aspects of the disclosure can also be described according to the following clauses. The subject matter of the following clauses can be combined with each of the other clauses provided, or any of the claims. Any combination of the claims and the clauses is contemplated by the present disclosure.

Clause 1 describes a method of air data probe icing detection and heating control, wherein the icing event is determined by detecting discontinuities of the mechanical signal produced by the probe in conjunction with temperature information obtained by inductive temperature sensing and other parameters relevant to the aircraft operation.

Clause 2 describes an air data probe, comprising: one or multiple induction coils employed adjacent to the parts of the probe where heating is required; and a control system that independently controls the frequency, current/voltage applied to each coil, causing coil to heat adjacent parts inductively.

Clause 3 describes an air data probe with a hybrid heating system in that induction heating coil is installed only in critical areas where high heat flux is needed, for example, a tip opening or other portion of the air data probe where ice accretion can affect reliability of a measurement of the air data probe, and the remaining portion of the air data probe is heated with electrical resistance wiring or elements.

Clause 4 describes a pitot tube, comprising: a straight portion comprising a tubular outer wall and a tubular air channel wall; a conical portion forming a frontal tip of the pitot tube, wherein the conical portion connects to the straight portion; a straight portion induction coil between the outer wall and the air channel wall; a conical induction coil within the conical portion; and a control system that independently controls a first alternating current (AC) signal applied to the straight portion induction coil and a second AC signal applied to the conical induction coil, causing the straight portion induction coil and the conical induction coil inductively heat the pitot tube.

Clause 5 describes the pitot tube of clause 4, further comprising: a flux controller material within the conical portion, wherein the flux controller material concentrates a magnetic field generated by the conical induction coil towards the frontal tip.

Clause 6 describes the pitot tube of any one of clauses 4 or 5, wherein the control system monitors a first temperature based at least in part on inductive temperature sensing using the conical induction coil, and a second temperature based at least in part on inductive temperature sensing using the straight portion induction coil.

Clause 7 describes the pitot tube of any one of clauses 4-6, wherein the control system adjusts the first AC signal to maintain the first temperature between a first threshold temperature range, and adjusts the second AC signal to maintain the second temperature between a second threshold temperature range.

Clause 8 describes the pitot tube of any one of clauses 4-7, further comprising: a secondary temperature sensor, wherein the control system calibrates the first temperature and the second temperature based at least in part on a temperature reading of the secondary temperature sensor.

Clause 9 describes the pitot tube of any one of clauses 4-8, wherein, based at least in part on a discontinuity identified in a mechanical signal reading, the control system increases power of at least one of: the first AC signal applied to the straight portion induction coil, and the second AC signal applied to the conical induction coil.

Clause 10 describes the pitot tube of any one of clauses 4-9, wherein, based at least in part on a threshold temperature being reached, the control system decreases power of at least one of: the first AC signal applied to the straight portion induction coil, and the second AC signal applied to the cone induction coil.

Clause 11 describes the pitot tube of any one of clauses 4-10, wherein the control system generates the first AC signal comprising a first frequency, and generates the second AC signal comprising a second frequency that differs from the first frequency.

Clause 12 describes an inductive pitot tube heating system, comprising: a first induction coil between an outer wall and an inner wall of an air data probe; a second induction coil within a frontal portion of the air data probe; and a control system that independently controls a first alternating current (AC) signal applied to the first induction coil and a second AC signal applied to the second induction coil, causing the first induction coil and the second induction coil inductively heat the air data probe.

Clause 13 describes the inductive pitot tube heating system of clause 12, wherein the control system monitors a first temperature based at least in part on inductive temperature sensing using the first induction coil, and a second temperature based at least in part on inductive temperature sensing using the second induction coil.

Clause 14 describes the inductive pitot tube heating system of any one of clauses 12 or 13, wherein the control system adjusts the first AC signal to maintain the first temperature between a first threshold temperature range, and adjusts the second AC signal to maintain the second temperature between a second threshold temperature range.

Clause 15 describes the inductive pitot tube heating system of any one of clauses 12-14, further comprising: a secondary temperature sensor, wherein the control system calibrates the first temperature and the second temperature based at least in part on a temperature reading of the secondary temperature sensor.

Clause 16 describes the inductive pitot tube heating system of any one of clauses 12-15, wherein, based at least in part on a discontinuity identified in a mechanical signal reading, the control system increases power of at least one of: the first AC and the second AC signal.

Clause 17 describes the inductive pitot tube heating system of any one of clauses 12-16 wherein, based at least in part on a threshold temperature being reached, the control system decreases power of at least one of: the first AC signal and the second AC signal.

Clause 18 describes the inductive pitot tube heating system of any one of clauses 12-17, wherein the control system generates the first AC signal comprising a first frequency, and generates the second AC signal comprising a second frequency that differs from the first frequency.

Clause 19 describes a pitot tube comprising: a straight portion comprising a tubular outer wall and a tubular air channel wall; a conical portion forming a frontal tip of the air data probe, wherein the conical portion connects to the straight portion; a straight portion heating component within the straight portion; a conical portion heating component within the conical portion; and a control system that independently controls a first power signal applied to the straight portion heating component and a second power signal applied to the conical section heating component, causing the straight portion heating component and the conical section heating component to heat the air data probe, wherein at least one of the straight portion heating component and the conical section heating component comprises an inductive heating coil.

It is emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations described for a clear understanding of the principles of the disclosure. Many variations and modifications can be made to the above-described embodiments without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included within the scope of this disclosure.

Claims

An air data probe, comprising:

a plurality of heating components employed corresponding to a plurality of portions of the air data probe, wherein the plurality of heating components comprises at least one induction heating coil; and

a control system that independently controls power signals to the heating components, wherein a power signal applied to an induction heating coil causes the induction heating coil to heat a corresponding portion of the air data probe inductively.
The air data probe of claim 1, wherein the plurality of heating components comprises at least one induction heating coil and at least one resistive heating element.
The air data probe of claim 2, wherein a resistive heating element is employed corresponding to a first portion of the air data probe and the induction heating coil is employed corresponding to a second portion of the air data probe.
The air data probe of claim 3, wherein the second portion of the air data probe is a critical portion of the air data probe, the critical portion being a portion of the air data probe where ice accretion can affect reliability of a measurement of the air data probe.
A pitot tube, comprising:

a straight portion comprising an outer tube and an inner air channel tube;

a conical portion that has a frontal opening that opens to an air channel formed by the inner air channel tube of the straight portion;

a straight portion induction coil between the outer tube and the inner air channel tube;

a conical induction coil within the conical portion; and

a control system that independently controls a first alternating current (AC) signal applied to the straight portion induction coil and a second AC signal applied to the conical induction coil, causing the straight portion induction coil and the conical induction coil inductively heat the pitot tube.
The pitot tube of claim 5, further comprising:

a vertical pressure line induction coil that is connected in parallel or in series with the straight portion induction coil.
The pitot tube of claim 5, further comprising:

a flux controller material within the conical portion, wherein the flux controller material concentrates a magnetic field generated by the conical induction coil towards a frontal tip of the conical portion.
The pitot tube of claim 5, further comprising:

insulation material between the conical induction coil and a body of the conical portion, and between the straight portion induction coil and the inner air channel tube.
The pitot tube of claim 8, wherein an insulation thickness between an inner surface of the conical portion induction coil and the body of the conical portion is thicker than an insulation thickness between another surface of the conical portion induction coil and the body of the conical portion.
The pitot tube of claim 5, further comprising:

axial leads for the conical induction coil and the straight portion induction coil installed in an annulus between the outer tube and the inner air channel tube.
The pitot tube of claim 5, further comprising:

filling material casted or molded around the straight portion induction coil.
The pitot tube of claim 5, wherein the control system monitors temperatures of different portions of the pitot tube based at least in part on inductive temperature sensing using some or all individual coils installed in the pitot tube.
The pitot tube of claim 12, wherein the control system independently adjusts the AC signals to maintain temperatures of corresponding portions of the pitot tube based on individually set temperature range thresholds for the AC signals.
A method of air data probe heating control, the method comprising:

generating, using the air data probe, a signal associated with a parameter of aircraft operation;

determining a temperature based at least in part on inductive temperature sensing using an induction heating coil;

detecting, by a control system, an icing event based at least in part on: a discontinuity of the signal generated by the air data probe; and

increasing, by the control system, a power of the induction heating coil based at least in part on the icing event being detected.
The method of air data probe heating control of claim 14, further comprising:

calibrating the inductive temperature sensing, wherein the control system calibrates the inductive temperature sensing based at least in part on a temperature reading of a secondary temperature sensor.
The method of air data probe heating control of claim 15, wherein the secondary temperature sensor is an electrical resistance element, and the electrical resistance element provides additional heating to the air data probe.
The method of air data probe heating control of claim 14, wherein, based at least in part on a threshold temperature being reached, the control system decreases a power of the induction heating coil.
The method of air data probe heating control of claim 14, wherein the control system generates one or more AC signal comprising different frequencies for a corresponding one or more induction heating coils.
The method of air data probe heating control of claim 14, wherein the control system applies power to the induction heating coil and a resistive heating element.
The method of air data probe heating control of claim 19, wherein the induction heating coil inductively heats a first portion of the air data probe, and the resistive heating element heats a second portion of the air data probe.