Patent Description:
Certain ice detectors can generate outputs which resemble icing signals in particular orientations and weather conditions. Activating the aircraft's de-icing systems in circumstances where icing conditions are not actually present can lead to wasted energy and higher costs.

<CIT> relates to an aircraft ice detection system comprising a thermochromic device for detecting a temperature of the free air relative to a temperature threshold, a hydrochromic device for detecting an amount of moisture in the free air relative to a moisture threshold, and a controller for detecting an ice condition in response to the thermochromic device detecting a temperature less than or equal to the temperature threshold and the hydrochromic device detecting an amount of moisture greater than the moisture threshold. <CIT>, <CIT>, <CIT>, <CIT> and <CIT> relate to other icing detection systems and methods.

According to one aspect of the invention, an ice detection system for an aircraft is defined in claim <NUM>.

According to another aspect of the invention, a method of verifying ice accretion signals from an ice detector of an aircraft is defined in claim <NUM>.

While the above-identified figures set forth one or more embodiments of the present disclosure, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings, insofar as they fall within the scope of the appended claims.

Ice detection systems, such as magnetostrictive probe ice detectors, allow for icing conditions to be reliably detected and measured in most circumstances. However, there is a need for verifying signals suggesting icing conditions which are generated by these ice detection systems in some environmental conditions and mounting orientations. An algorithm can use input data from the temperature sensor present in the ice detector to determine whether icing conditions are likely to be present, allowing icing conditions signals to be distinguished from similar signals without altering the hardware of the probe or surrounding systems.

<FIG> is a simplified perspective view of a forward portion of aircraft <NUM>. Aircraft <NUM> includes engine <NUM>, wing <NUM>, and ice detector <NUM>. Engine <NUM> includes engine cowl <NUM>. Wing <NUM> includes external wing surface <NUM>, which includes bottom wing surface <NUM>.

In the illustrated example, ice detector <NUM> is a probe ice detector located on the bottom of wing <NUM> such that the probe section of ice detector <NUM> is in contact with airflow passing underneath wing <NUM>. Ice detector <NUM> can be any ice detector which is capable of detecting when icing conditions are encountered by aircraft surfaces such as wing <NUM>, and can in some examples be a magnetostrictive ice detector. Other ice detectors <NUM> can be located on other external surfaces of the aircraft, such as engine cowl <NUM>, another surface of the nacelle of engine <NUM>, on the side of the nose behind the cockpit windows, or at another location on the fuselage.

Ice detector <NUM> is installed at an orientation selected to permit detection of ice conditions on wing <NUM> or other parts of the aircraft. Under certain circumstances, water runoff along ice detector <NUM> can produce a signal which resembles an icing conditions signal. The present application contemplates an approach to further distinguish between icing conditions signals and signals generated under other circumstances.

<FIG> is a perspective view of ice detector <NUM> oriented along axis A-A. In the example shown in <FIG>, ice detector <NUM> includes probe <NUM>, strut <NUM>, mounting plate <NUM>, and electronics housing <NUM>. Probe <NUM> includes distal end <NUM>.

Probe <NUM> extends from strut <NUM> along axis A-A, and strut <NUM> is disposed between probe <NUM> and mounting plate <NUM>. Probe <NUM> can be at least partially composed of a ferromagnetic material. Probe <NUM> can have an approximately cylindrical shape and can taper to a rounded point at distal end <NUM> of probe <NUM>. Strut <NUM> can have a wider diameter than probe <NUM> in at least one direction, and in some examples can have an approximately teardrop or airfoil shape. Mounting plate <NUM> can extend radially outward with respect to axis A-A and can have an approximate shape of a flat disk. Electronics housing <NUM> extends along axis A-A and can have an approximately cylindrical shape. As described in more detail below, strut <NUM> and electronics housing <NUM> can surround and contain electronic components of ice detector <NUM>.

Ice detector <NUM> can be configured to be installed in the external surface of aircraft <NUM>. This external surface can be wing <NUM>. Mounting plate <NUM> can be configured to secure ice detector <NUM> to the external surface of aircraft <NUM> in which ice detector <NUM> is disposed. In the example shown in <FIG>, mounting plate <NUM> includes mounting holes through which screws, bolts, or other suitable connectors can be inserted to connect ice detector <NUM> to an external surface of aircraft <NUM>. In examples where ice detector <NUM> does not include a probe, ice detector <NUM> can be mounted flush to the surface of aircraft <NUM>.

<FIG> is a schematic partial cross-sectional view of ice detector <NUM>. In the example shown in <FIG>, ice detector <NUM> includes probe <NUM> with distal end <NUM>, strut <NUM>, mounting plate <NUM>, electronics housing <NUM>, drive coil <NUM>, feedback coil <NUM>, strut heaters <NUM>, and probe heater <NUM>.

Drive coil <NUM> and feedback coil <NUM> can surround the base of probe <NUM>. Feedback coil <NUM> can be situated about probe <NUM> such that feedback coil <NUM> is between drive coil <NUM> and distal end <NUM>. Drive coil <NUM> and feedback coil <NUM> can form part of an oscillation circuit within ice detector <NUM>. Strut heaters <NUM> can extend along strut <NUM> in a direction aligned with axis A-A (shown in <FIG>). Probe heater <NUM> can extend along the outer surface of probe <NUM>.

During operation, probe <NUM> vibrates in the direction of double-ended arrow V. The vibration of probe <NUM> is caused by drive coil <NUM>, which drives probe <NUM> to vibrate at a set frequency. Feedback coil <NUM> collects vibration data from probe <NUM> and can communicate this vibration data to an ice sensor (not shown in <FIG>). As described in more detail below, the frequency shift experienced by probe <NUM> allows ice detector <NUM> to detect icing conditions. When ice accretes on probe <NUM>, strut heaters <NUM> and probe heater <NUM> can be activated to remove the ice. In some examples, the ice detector does not include an oscillation circuit and utilizes different ice sensing techniques (that is, non-magnetostrictive ice sensing techniques).

<FIG> is a graph of the frequency shift of ice detector <NUM> (illustrated in <FIG>) undergoing cycles of ice accretion and heating. Frequency shift line F includes frequency shift minimum points Fmin and frequency shift maximum points Fmax.

As described above in reference to <FIG>, ice detector <NUM> can be a magnetostrictive ice detector containing a ferromagnetic material which changes dimension in the presence of a fluctuating electromagnetic field. Drive coil <NUM> causes probe <NUM> to vibrate at a set resonant frequency. As ice accretes on probe <NUM>, the vibrational frequency decreases, and the frequency shift (the difference between the set resonant frequency and the experienced vibrational frequency) accordingly increases. A frequency shift maximum can be selected, and when probe <NUM> reaches the frequency shift maximum (shown by frequency shift maximum points Fmax), an ice accretion signal can be generated and strut heaters <NUM> and probe heater <NUM> can be used to remove the ice from probe <NUM>. After the ice is removed, strut heaters <NUM> and probe heater <NUM> are switched off. Probe <NUM> cools to the total air temperature and reaches the frequency shift minimum (shown by frequency shift minimum points Fmin) by returning to the set resonant frequency driven by drive coil <NUM>. The ice accretion signals can be used to count the number and length of these ice accretion and heating cycles in order to provide information about environmental conditions to the cockpit.

<FIG> is a system logic diagram of ice protection system <NUM>. Ice protection system <NUM> includes ice detectors <NUM>, controller <NUM>, cockpit annunciation system <NUM>, engine cowl de-icing system <NUM>, and wing de-icing system <NUM>.

Ice detectors <NUM> can be disposed within surfaces of the aircraft such as the engine cowl, fuselage, or wing. When one of ice detectors <NUM> accretes enough ice to undergo a specified frequency shift (as described above in reference to <FIG>), an icing conditions signal can be sent from that ice detector <NUM> to controller <NUM>. Controller <NUM> can verify the icing conditions signal using an icing threshold module (such as icing threshold module <NUM>, described below in reference to <FIG>). Controller <NUM> can then suppress or send an icing conditions alert to cockpit annunciation system <NUM>, as well as engine cowl de-icing system <NUM> and/or wing de-icing system <NUM>. Cockpit annunciation system <NUM> can be configured to display an alert message, emit an audible repeating or non-repeating signal, or otherwise inform a person in the cockpit of the icing conditions which have been detected by ice detector(s) <NUM>. Engine cowl de-icing system <NUM> and wing de-icing system <NUM> can be selectively activated based on the number and frequency of ice accretion cycles as shown in <FIG>. In some examples, engine cowl de-icing system <NUM> and/or wing de-icing system <NUM> can be activated by input from the cockpit which is processed by controller <NUM>.

<FIG> is a system diagram illustrating modules of controller <NUM> that interfaces with ice detection system <NUM>. Controller <NUM> includes processor(s) <NUM>, communication unit(s) <NUM>, memory unit(s) <NUM>, icing threshold module <NUM>, input device(s) <NUM>, output device(s) <NUM>, and alert module <NUM>. Ice detection system <NUM> can include one or more ice detectors <NUM> (shown in <FIG>). Ice detector(s) <NUM> can include temperature sensor(s) <NUM>, oscillation circuit(s) <NUM>, and ice sensor(s) <NUM>. While controller <NUM> is illustrated separately from ice detection system <NUM> for clarity, controller <NUM> can be a component of ice detection system <NUM>. Ice detection system <NUM> can additionally include an external aircraft surface, such as external wing surface <NUM>, engine cowl <NUM>, another surface of the nacelle of engine <NUM>, or the fuselage surface (shown in <FIG>).

As described above, controller <NUM> can include processor <NUM>, communication unit <NUM>, memory unit <NUM>, input device <NUM>, and output device <NUM>. In some examples, controller <NUM> can include multiple processors <NUM>, communication units <NUM>, memory units <NUM>, input devices <NUM>, and/or output devices <NUM>. In other examples, one or more of processor <NUM>, communication unit <NUM>, memory unit <NUM>, icing threshold module <NUM>, input device <NUM>, output device <NUM>, and alert module <NUM> can be externally located to controller <NUM>. Controller <NUM> can additionally include more components, such as a power source. It should be understood that, while reference is made to a single controller <NUM> for clarity, in some examples there can be multiple controllers <NUM> and/or multiple systems (which can include redundancies) which make up a single controller <NUM>. Additionally, while the components of controller <NUM> are described below as discrete parts, any of the disclosed components can form a subcomponent of the other disclosed components or can otherwise be combined. In some examples, controller <NUM> is a component of ice detector <NUM> and can be embedded partially or entirely within ice detector <NUM> (such that some or all of the components of controller <NUM> are also part of ice detector <NUM>).

Processor <NUM> can be configured to implement functionality and/or process instructions for execution within controller <NUM>. For example, processor <NUM> can be capable of processing instructions stored in memory unit <NUM>. Processor <NUM> can be any one or more of a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FGPA), or other equivalent discrete or integrated logic circuitry. In some examples, processor <NUM> can be configured to calculate an icing threshold temperature, above which icing conditions are unlikely to occur. Processor <NUM> can calculate this icing threshold temperature using one or more environmental and operational parameters. According to the invention, the calculation of the icing threshold temperature can include an offset value of the expected residual heat experienced by temperature sensor <NUM>. This residual heat can be from electronics within or near temperature sensor <NUM>. The calculation of the icing threshold temperature can additionally and/or alternatively include the total air temperature experienced by temperature sensor <NUM>. Airflow has an amount of kinetic energy which can vary based on the speed of the airflow relative to the aircraft, and the total air temperature incorporates this kinetic energy value. In an illustrative example not covered by the scope of the appended claims, the calculation of the icing threshold temperature can additionally and/or alternatively include a known or expected tolerance of the temperature sensor.

Controller <NUM> can also include communication unit <NUM>. Controller <NUM> can utilize communication unit <NUM> to communicate with other components of controller <NUM> and external devices via one or more networks, such as one or more wireless and/or wired networks. Communication unit <NUM> can be a network interface card, such as an Ethernet card, an optical transceiver, a radio frequency transceiver, or any other type of device that can send and receive information. For example, communication unit <NUM> can be a radio frequency transmitter dedicated to Bluetooth or WiFi bands or commercial networks such as GSM, UMTS, <NUM>, <NUM>, <NUM>, and others. Alternatively, communication unit <NUM> can be a Universal Serial Bus (USB) or can utilize ARINC, CAN Bus, or RS-<NUM> protocols.

Memory unit <NUM> can be configured to store information within controller <NUM> during operation. Memory unit <NUM>, in some examples, is described as a computer-readable storage medium. In some examples, a computer-readable storage medium can include a non-transitory medium. The term "non-transitory" can indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium can store data that can, over time, change (e.g., in RAM or cache). In some examples, memory unit <NUM> is a temporary memory, meaning that a primary purpose of memory unit <NUM> is not long-term storage. Memory unit <NUM>, in some examples, is described as volatile memory, meaning that memory unit <NUM> does not maintain stored contents when power to controller <NUM> is turned off. Examples of volatile memories can include random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), and other forms of volatile memory. In some examples, memory unit <NUM> is used to store program instructions for execution by processor <NUM>.

Memory unit <NUM> can be configured to store larger amounts of information than volatile memory. Memory unit <NUM> can further be configured for long-term storage of information. In some examples, memory unit <NUM> includes non-volatile storage elements. Examples of such non-volatile storage elements can include magnetic hard discs, optical discs, flash memory, or forms of erasable programmable read-only memory (EPROM) or electrically erasable programmable read-only (EEPROM) memory.

Icing threshold module <NUM> can be an algorithm or other software program which can analyze input data about the temperature and vibrational frequency of probe <NUM> in order to verify or suppress icing conditions alerts. In some examples, icing threshold module <NUM> can be configured to receive a selected icing threshold temperature from a component of controller <NUM>, such as input device <NUM>. Icing threshold module <NUM> can be configured to receive temperature measurements from temperature sensor <NUM> and ice accretion signals from ice sensor <NUM>. Icing threshold module <NUM> can be further configured to compare the temperature measurement to the icing threshold temperature and determine if the temperature measurement is above the icing threshold temperature. Controller <NUM> can be configured to suppress an icing conditions alert if the temperature measurement is above the icing threshold temperature. Conversely, controller <NUM> can allow the icing conditions alert to be communicated to alert module <NUM> if the temperature measurement is at or below the icing threshold temperature.

Input device <NUM> can include a mouse, a keyboard, a microphone, a camera device, a presence-sensitive and/or touch-sensitive display, or other type of device configured to receive input from a user. Input device <NUM> can, in some examples, be configured to allow a user to select an icing threshold temperature. Output device <NUM> can include a display device, a sound card, a video graphics card, a speaker, a liquid crystal display (LCD), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, or other type of device for outputting information in a form understandable to users or machines. Output device <NUM> can form part of cockpit annunciation system <NUM> (described above in reference to <FIG>).

Alert module <NUM> can be hardware- or software-based. In some examples, alert module can be a software program which is configured to communicate and/or display alerts.

Temperature sensor <NUM> can be a sensor which is situated and configured to measure the temperature experienced by probe <NUM>. In the example depicted in <FIG>, temperature sensor <NUM> is a component of ice detector <NUM>. In other examples, temperature sensor <NUM> can be located within or adjacent to probe <NUM>, within strut <NUM> or electronics housing <NUM>, or completely external to ice detector <NUM>. For examples where temperature sensor <NUM> is external to and separately located from ice detector <NUM>, ice detector <NUM> can be configured to receive the aircraft temperature sensor signal from an aircraft data bus and use that temperature measurement to determine whether to suppress the icing conditions signal.

Oscillation circuit <NUM> can include drive coil <NUM> and feedback coil <NUM> (both described above in reference to <FIG>). Oscillation circuit <NUM> drives probe <NUM> to vibrate at a set resonant frequency. Ice sensor <NUM> is a suitable means for sensing or measuring one or more parameters which can indicate the presence of icing conditions. In examples where ice detector <NUM> is a probe ice detector, ice sensor <NUM> can be a sensor which is configured to receive vibration data from feedback coil <NUM> within oscillation circuit <NUM>. As described above in reference to <FIG>, the frequency shift of probe <NUM> can indicate ice accretion on probe <NUM>. Ice sensor <NUM> can generate an ice accretion signal if the frequency shift of probe <NUM> reaches a set point (such as frequency shift maximum point Fmax, described above in reference to <FIG>).

As described in more detail below, the components of controller <NUM> can be configured to verify and/or suppress icing conditions alerts generated when ice sensor <NUM> of ice detector <NUM> detects a shift in the vibrational frequency of probe <NUM>.

<FIG> is a flowchart illustrating method <NUM> of verifying icing signals generated by an ice detector. Method <NUM> includes steps <NUM>-<NUM>.

In step <NUM>, an input device (such as input device <NUM>, described above in reference to <FIG>) selects an icing threshold temperature, above which icing conditions alerts can be suppressed. This selection can be done automatically or manually, and can be selected based on one or more user inputs or calculated with expected parameters, or the threshold could be fixed as part of the design. As described above in reference to <FIG>, these parameters can include an offset to account for residual heat from electronics (which depends on the location of ice detector <NUM> on aircraft <NUM>), and/or total temperature effects to account for the kinetic energy of the airflow. Alternatively, this selection of an icing threshold temperature can be done with icing threshold module <NUM> directly.

In step <NUM>, a communication unit (such as communication unit <NUM>, described above in reference to <FIG>) communicates the icing threshold temperature selected in step <NUM> to an icing threshold module (such as icing threshold module <NUM>, described above in reference to <FIG>). This can be performed through the use of one or more wired or wireless networks.

In step <NUM>, the communication unit receives an ice accretion signal from an ice sensor within an ice detector (such as ice sensor <NUM> within ice detector <NUM>, described above in reference to <FIG>) when icing conditions are detected. For a magnetostrictive probe ice detector, icing conditions are detected when the vibrational frequency of the probe shifts by a selected amount. The communication unit further receives a temperature measurement from a temperature sensor (such as temperature sensor <NUM>, described above in reference to <FIG>). This temperature measurement can be the total air temperature experienced by the ice detector.

In step <NUM>, the communication unit communicates the ice accretion signal and the temperature measurement to the icing threshold module. This can be performed in the same manner as step <NUM>, or another suitable communication method.

In step <NUM>, the icing threshold module compares the temperature measurement received in step <NUM> to the icing threshold temperature selected in step <NUM>. This can be performed using conventional calculation methods.

In step <NUM>, the icing threshold module determines if the temperature measurement received in step <NUM> is above the icing threshold temperature.

In step <NUM>, an icing conditions alert can be suppressed if the icing threshold module determines that the temperature measurement is above the icing threshold temperature. Generally, an icing conditions alert can be communicated to the cockpit if ice accretion is detected on the probe by the ice sensor. However, if the temperature experienced by the probe is above the icing threshold temperature, it is unlikely that icing conditions are present and the icing conditions alert can therefore be suppressed before it is communicated to the cockpit. The suppression of the icing conditions alert can be performed by one or more components of controller <NUM>, such as alert module <NUM>, output device <NUM>, and/or icing threshold module <NUM>. The icing conditions alert can be suppressed after it is generated (i.e., suppressed in transit) or can be suppressed by not being generated.

An ice detector as described herein provides numerous advantages. An icing threshold module for use with an ice detector can help to verify ice accretion signals. This can decrease the number of spurious icing signals, decrease energy usage and costs associated with running de-icing systems, and increase user confidence in the ice detection system.

Claim 1:
An ice detection system for an aircraft, the ice detection system comprising:
an ice detector (<NUM>) configured to be disposed in an external aircraft surface, the ice detector comprising an ice sensor (<NUM>);
a temperature sensor (<NUM>); and
a controller (<NUM>) comprising:
an icing threshold module (<NUM>) which is configured to:
receive a temperature measurement from the temperature sensor;
receive an ice accretion signal from the ice sensor;
receive a selected icing threshold temperature from the controller, the icing threshold temperature calculated using at least one of: an offset value of expected residual heat experienced by the temperature sensor, and a total air temperature experienced by the temperature sensor due to a kinetic energy of airflow;
compare the temperature measurement to the icing threshold temperature; and
determine whether the temperature measurement is above the icing threshold temperature;
wherein the controller is configured to suppress an icing conditions alert if the temperature measurement is above the icing threshold temperature.