Aircraft surface ice detection system and method of operation of the ice detection system

Abstract

To provide an ice detection system for an aircraft surface.SOLUTION: An ice detection system for an aircraft surface comprises: a sensor assembly (10) comprising a plurality of temperature sensitive elements configured to be arranged at respective points on the aircraft surface; a control unit (20) arranged to receive signals indicative of a temperature sensed by each of the temperature sensitive elements; a signal conducting bus (50) to transmit the signals from the temperature sensitive elements to the control unit; and means for providing power to the sensor assembly. The sensor assembly further comprises a multiplexer (40) arranged to multiplex the signals from the plurality of temperature sensitive elements into a single signal for transmission on the signal conducting bus to the control unit.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to systems and methods for sensing temperature on any aircraft surface, such as, but not limited to, wings, flaps, slats, rotors, etc., to detect conditions where ice is forming or likely to form. [Background technology]

[0002] Icing on aircraft surfaces can cause damage to the surfaces and can even have adverse effects on the operation of the aircraft in flight, thereby having catastrophic consequences. Icing in aircraft engines, on airfoil surfaces, or on propellers or rotors can be particularly dangerous. Icing can increase the weight of the aircraft, cause imbalances, block or change the intake passages, and / or impede the movement of moving parts. Therefore, icing needs to be detected reliably and quickly.

[0003] Most commercial aircraft are equipped with heaters or other de-icing systems to remove or reduce ice formation during flight. Additionally or alternatively, an alarm may be activated if icing is determined. Aircraft are also de-iced prior to takeoff in conditions where ice may form on the surface of the aircraft. Upon detection of icing, a temperature measurement is made or a signal is generated indicative of temperature or temperature change, and de-icing is performed if a temperature below a given threshold is determined.

[0004] A conventional ice detection system includes an array of temperature sensors disposed on or connected to the surface to be monitored. Each of the sensors is connected to a control unit by a respective wire. Each sensor transmits a signal along the wire(s) to the control unit indicative of the temperature at the sensor's location. The signal may be, for example, an electrical signal such as a voltage or current. The signal is then processed in the control unit to provide an indication of icing or impending icing and trigger an alarm and / or de-icing / heating. The temperature sensors are temperature sensing elements of which various types are known in the art. The number of wires between the sensor array and the control unit depends on the number of temperature sensing elements. A commonly used sensor is a 3-wire RTD, and in such a configuration, each sensor element is connected to the control unit via three wires. Power lines are also provided to the sensor assembly. Thus, such a system involves a large number of wires to and from the sensor, which increases by a factor of three for each additional sensor.

[0005] The use of multiple wires adds weight and complexity to the system and introduces multiple potential points of failure. Each additional wire reduces the mechanical reliability of the system. Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a system and method for ice detection that uses less wiring than conventional systems. [Means for solving the problem]

[0007] Thus, there is provided an ice detection system for an aircraft surface comprising a sensor assembly including a plurality of temperature sensing elements configured to be positioned at respective points on the aircraft surface, a control unit configured to receive a signal indicative of a temperature sensed by each of the temperature sensing elements, a signal conducting bus for transmitting signals from the temperature sensing elements to the control unit, and means for providing power to the sensor assembly, the sensor assembly further including a multiplexer configured to multiplex signals from the plurality of temperature sensing elements into a single signal for transmission to the control unit on the signal conducting bus.

[0008] Different types of multiplexing can be used as known in the art.

[0009] The temperature sensing element may be any known temperature sensor, such as a resistance temperature detector (RTD), for example a 3-wire RTD.

[0010] In an embodiment, the means for providing power to the sensor assembly provides power to the multiplexer via a step-down voltage regulator, e.g., a Zener voltage regulator, a linear voltage regulator, a power switching voltage regulator, etc. Other power sources may also be used.

[0011] The control unit preferably evaluates the signal, for example by comparing the signal to a threshold value, and controls the heater and / or de-icing device, and / or alarm depending on the comparison. The signal may be evaluated in other manners, such as, but not limited to, using detection and / or discrimination algorithms to distinguish between different icing application conditions. Again, depending on the evaluation, estimation, or determination of a particular condition, an action may be triggered, such as, for example, activating a heater, de-icer, alarm, etc.

[0012] Also provided is a method of operating an ice detection system that includes detecting temperatures at a plurality of locations on an aircraft surface, combining the detected temperatures into a single multiplexed signal for transmission to a control unit, comparing the temperatures to a threshold value, identifying temperatures indicative of icing based on the comparison, and identifying locations at which such temperatures are detected.

[0013] The method may then be further used to operate a heater or de-icing device at the identified location(s).

[0014] Preferred embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which: [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of an ice detection system known in the prior art; [Figure 1A] 1 is a more detailed diagram of a known ice detection system. [Diagram 2] 1 is a schematic diagram of an ice detection system according to the present disclosure. [Figure 2A] FIG. 2 is a more detailed diagram of an ice detection system according to the present disclosure. [Figure 2B] FIG. 2 is a more detailed diagram of an alternative ice detection system according to the present disclosure. [Diagram 3] FIG. 1 is a circuit diagram of a voltage regulator that may be used in a system according to the disclosure. [Figure 4] FIG. 1 is a block diagram for signal conditioning of an acquired temperature signal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A known ice detection system will be briefly described with reference to Figures 1 and 1A. The system includes a sensor assembly 1 connected to a control unit 2. The sensor assembly includes a number of temperature sensing elements 6 that are placed at various locations on the aircraft surface, e.g., airfoils, blades, engines, etc. (not shown), to measure temperatures at or near such locations. Power is provided to the sensor assembly via a power bus 3 and may be provided from or via the control unit 2. Alternatively, the sensor assembly may be powered by a different source.

[0017] Each of the temperature sensing elements 6 outputs a signal indicative of the temperature sensed by that sensing element. Each signal is transmitted to the control unit via one or more wires 5. In the embodiment shown, the sensors are resistance temperature detectors (RTDs), whose resistance increases as temperature increases. In an embodiment, so-called 3-wire RTDs are used to minimize the effect of lead resistance. Thus, three signal wires are provided for each temperature sensing element. Of course, other temperature sensors may be used.

[0018] The control unit evaluates the detected temperatures using a number of signal conditioners 7, for example by comparison with predefined thresholds and / or by implementing detection and discrimination algorithms, to determine icing conditions or conditions indicative of impending or possible icing, which may be used to activate heaters (not shown) and / or other de-icing devices (not shown) and / or trigger alarms (not shown).

[0019] Referring now to FIG. 2, the system of the present disclosure solves the problems of systems such as that shown in FIG. 1 by avoiding the need for multiple wires 5 from the sensor assemblies to the control unit, thereby resulting in a more reliable system.

[0020] Similar to conventional systems, the disclosed system includes a sensor assembly 10, which includes a number of temperature sensing elements (not shown), and a control unit 20. Power is provided to the sensor assembly 10 via a power bus 30.

[0021] The sensor assembly 10 is provided with a multiplexer 40 which receives the output signal from each of the temperature sensing elements and multiplexes them all onto a single output signal for transmission on a signal bus 50 to the control unit 20. As with known configurations, many types of temperature sensors may be used. In an embodiment, a 3-wire RTD is used. An input signal (demux signal) is provided to the multiplexer to be transmitted along with the temperature signal on the bus 50 to identify which temperature measurement is from which temperature sensing element. In an embodiment, the multiplexer may be a single chip device.

[0022] Figures 2A and 2B show in more detail a possible embodiment of a system such as that described above in relation to figure 2. In the example shown, the control unit 10 is provided on a controller board 100 and includes a processor, here a digital signal processor DSP 200, an analogue to digital converter ADC 300 and a signal conditioning circuit 400.

[0023] As described above, the sensor assembly 10 includes a multiplexer 40 and a number of sensors. The sensors can have different configurations. In one embodiment shown in Figure 2A, the sensor may be a three-wire RTD 500 that is connected to the multiplexer 40 such that both ends of the RTD are connected to the controller board through the multiplexer. In the configuration of Figure 2B, the RTD 500' is connected to the controller board through a multiplexer via a three-wire system.

[0024] In a preferred embodiment, the power transmitted to the sensor assembly 10 over the bus 30 may also be used to power the multiplexer. In the example shown, a step-down regulator 60 steps down the power to an appropriate level for supplying the multiplexer. The step-down regulator may be, for example, a Zener voltage regulator as shown in FIG. 3. Of course, other power supplies and / or regulators may be used to provide an appropriate power supply to the multiplexer 40.

[0025] Referring now to FIG. 4, the temperature signal may be conditioned as follows.

[0026] A current source 600 generates a current signal, for example 1 mA to 10 mA, which is fed to a sensing element, here an RTD 500, to generate a voltage signal correlated to the temperature sensed by the RTD. This is then sent to the control unit (via multiplexer 40) for signal conditioning. The signal conditioning includes error compensation 700, and anti-aliasing and noise rejection 800. After conditioning, the signal is passed to the ADC 300.

[0027] The error compensation block 700 compensates for errors in the measurement due to the wire / cable resistance from the RTD.

[0028] The anti-aliasing filter and noise removal block 800 removes high order harmonics to maintain the signal integrity required for the application.

[0029] The system of the present disclosure significantly reduces the amount of wiring in the ice detection system, thereby lowering the mechanical failure rate of the system. Furthermore, the control unit only needs to process data from the signal input bus, which reduces the components required for signal conditioning and acquisition.

[0030] The described embodiments are merely examples, and the scope of the present disclosure is limited only by the claims.

Claims

1. 1. An aircraft surface ice detection system comprising: a sensor assembly (10) including a plurality of temperature sensing elements (500) configured to be positioned at respective points on the aircraft surface; a control unit (20) configured to receive signals indicative of temperatures sensed by each of the temperature sensing elements; a single signal conducting bus (50) for transmitting the signals from the temperature sensing elements to the control unit; a power source; and a single power bus (30) for providing power from the power source to the plurality of temperature sensing elements (500) on the sensor assembly (10); wherein the sensor assembly (10) further comprises a multiplexer (40) configured to receive the signals output from each of the plurality of temperature sensing elements (500) and multiplex the signals from the plurality of temperature sensing elements into a single signal for transmission to the control unit on the single signal conducting bus (50); The system, wherein the single power bus (30) provides power from the power supply through a step-down regulator (60) to the multiplexer (40).

2. The system of claim 1 , wherein the temperature sensing element is a resistance temperature detector.

3. The system of claim 2 , wherein the temperature sensing element is a three-wire resistance temperature detector.

4. The system according to any one of claims 1 to 3, wherein the signal is a voltage signal.

5. The system according to any one of claims 1 to 3, wherein the signal is a current signal.

6. 2. The system of claim 1, wherein the step-down regulator is a Zener voltage regulator, a linear voltage regulator, or a power switching voltage regulator.

7. The system according to any one of the preceding claims, wherein the received signal is evaluated for controlling a heating device.

8. A system according to any one of the preceding claims, wherein the received signal is evaluated for controlling a de-icing device.

9. A system according to any preceding claim, wherein an alarm is triggered based on said signal.

10. The system according to any one of claims 1 to 9, wherein the signal is evaluated by comparison with a predetermined threshold value.

11. The system according to any one of claims 1 to 10, wherein the signal is evaluated by a detection and discrimination algorithm.

12. A method of operating an ice detection system comprising: detecting temperatures at a plurality of locations on an aircraft surface using a plurality of temperature sensing elements (500); combining said detected temperatures into a single multiplexed signal using a multiplexer (40) for transmission over a single signal conducting bus (50) to a control unit; evaluating said temperatures in said control unit; identifying temperatures indicative of icing based on said comparison; and identifying the locations at which such temperatures were detected; Provide power from the power source, a single power bus (30) supplies power from the power supply to the plurality of temperature sensing elements and from the power supply via a step-down regulator (60) to the multiplexer; The method further comprises:

13. The method of claim 12 , further comprising operating a heater or de-icing device at the location(s) identified based on the detected temperature.

14. The method of claim 12 or 13, further comprising triggering an alarm based on the identified temperature.

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