Aircraft wet wing

An aircraft wing (12) comprising a structural casing (14) defining a leading edge, a fuel cell (16) within the structural casing (14), a deicer (18) having electrical lines which receive a supply of electrical power from an onboard power source, and a trip line (20). The trip line (20) is positioned to receive early contact upon impact of the wing by a bird or other foreign object and disruption of the trip line triggers termination of the supply of electrical power to the deicer (18).

FIELD OF THE INVENTION

This application relates generally, as indicated, to an aircraft wet wing, and, more particularly, to an aircraft wet wing having a deicer installed on its leading edge.

BACKGROUND OF THE INVENTION

An aircraft wing can be designed to carry fuel for the aircraft and, to this end, the wing can comprise a fuel cell within its structural casing. Such an aircraft wing (often called a “wet wing”) can also include a deicer installed on its leading edge to remove ice that forms thereon during flight. A deicer will commonly be electrically heated and/or electrically controlled whereby electric lines will be present on the wing, sometimes in the vicinity of the fuel cell.

SUMMARY OF THE INVENTION

The present invention provides an electrical trip line for an aircraft wet wing. The trip line can be used in conjunction with a deicer having electric lines at risk of being severed, damaged or exposed during flight by, for example, impact with a bird or other foreign object. With such a deicer, if power is continued to be supplied after impact to the electrical lines, a voltage potential could be present near the fuel cell. The trip line of the present invention senses an impact so that, upon impact, electric power supply to the deicer may be immediately discontinued and thereby prevent a voltage potential near the fuel cell.

More particularly, the present invention provides an aircraft wing comprising a structural casing defining a leading edge, a fuel cell within the structural casing, a deicer having electrical lines which receive a supply of electrical power from an onboard power source, and a trip line. Upon impact of the wing by a bird or other foreign object, the trip line will receive early contact (e.g., before, at the same time, or slightly after the electrical lines are impacted) and be disrupted. Disruption of the trip line triggers termination of the supply of electrical power to the deicer.

The present invention may be employed on a wet wing, or any impact-susceptible part of an aircraft wherein electrical lines are located near a fuel container. The invention may also be useful in situations where fuel is not an issue, to prevent, for example, an electrical short to the frame of the aircraft. These and other features of the invention are fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail a certain illustrative embodiment of the invention, this embodiment being indicative of but one of the various ways in which the principles of the invention may be employed.

DETAILED DESCRIPTION

Referring now to the drawings in detail, and initially toFIG. 1, an aircraft10having a pair of wet wings12according to the present invention is shown. As is shown in more detail inFIG. 2, the wet wing12includes a structural casing14defining a leading edge, a fuel cell16within the structural casing14, an electrically controlled and/or powered deicer18, and a trip line20. Although not specifically shown in the drawings, the wing12can additionally include honeycomb or another light-weight material filling the space between the structural casing14and the fuel cell16.

The deicer18can be, for example, an electromechanical deicing device, an electro-thermal ice-protection device, or any other device that receives electrical power from an onboard power source (e.g., power source46introduced below). In the context of the present invention, “deicer” is intended to cover both devices which remove ice after it has formed on the relevant surface and devices which prevent formation of ice on the relevant surface. The latter devices are sometimes referred to as anti-icers or anti-icing devices.

The deicer18includes electrical lines or conductors (not specifically shown) that are positioned with respect to the casing14in the vicinity of the fuel cell16. If these electric lines are ruptured, severed, exposed, or otherwise damaged during flight, a voltage potential could be present near the fuel cell16. The trip line20is used to sense impact of a bird or other foreign object with the wing12and invoke shut-off of electric power to the deicer18if the wing12is impacted by a bird or other foreign object during flight.

Referring now additionally toFIG. 3, the trip line20can be printed on or otherwise carried by a substrate22. The substrate22can comprise any suitable substrate, such as a dielectric substrate, which adequately carries the trip line20and which can be appropriately installed on the desired portion of the aircraft. For example, in the illustrated embodiment, the substrate22is positioned around the leading edge of the wing12whereby it should be capable of accommodating this curved contour. Also in the illustrated embodiment, the substrate22outlines the shape of the trip line20although other arrangements are certainly possible. Although not specifically shown in the drawing, an electric shield can be provided around the trip line20to provide shielding from radiated electrical interference to minimize the risk of false triggering.

The trip line20comprises a first end24, a second end26, and when the trip line20is intact, a conductive path therebetween. The conductive path can be established by a single conductor, wire or trace, or, as shown, plural parallel conductors, wires or traces. The trip line20, is shaped, arranged, and/or positioned to receive early contact upon the wing12being impacted by a bird or other foreign object. “Early contact” in the context of the present invention refers to the trip line20being contacted before, at the same time as, or slightly after (i.e., less than 1 millisecond after) the relevant electrical lines. In any event, the trip line20is positioned to receive impact contact prior to the fuel cell16and, as explained in more detail below, to allow power cut off prior to the impact reaching the fuel cell16.

In the illustrated embodiment, the trip line20has a flattened “S” shape with relatively long span sections28,30and32, and connecting sections34and36therebetween. The first span section28can be positioned along an upper wing side, the second span section30can be positioned along the leading edge, and the third span section32can be positioned along the lower wing side. However, other shapes, sizes or arrangements that place the trip line20in a position for contact before, at the same time, or slightly after the relevant electrical lines, are certainly possible with, and contemplated by the present invention.

Referring additionally toFIG. 4, a block diagram of an object-strike protection circuit38is provided. Upon detection of a bird or foreign object strike (i.e., upon disruption of the trip line20), the circuit38shuts off electrical power to the deicer18. The electrical power is shut off in a very rapid manner, specifically within a window of time between when the disruption of the conductivity of the trip line20and the predicted potential impact of the object with the fuel cell16. Thus, shut-off time is a function of the airspeed of the aircraft10, airspeed of the impacting object and the position of the fuel cell16relative to the leading edge. For example, with an expected airspeed of a bird relative to an aircraft is 270 knots (i.e., about 5470 inches per second) and the fuel cell16positioned six inches aft of the leading edge, the electrical power to the deicer18should be shut off within 1.097 milliseconds. In any event, the window of time between the conductive path of the trip line20being disrupted and the shut-off of electrical power is preferably less than 5 milliseconds, less than 4 milliseconds, less than 3 milliseconds, less than 2 milliseconds and/or less than 1 millisecond.

The object-strike protection circuit38includes a strike detector40(which includes the trip line20) and a switching circuit42. The circuit38may further include additional sensors or detectors, such as the illustrated over-current detector44. The circuit38may be coupled to a power source46, such as a single phase or multi-phase alternating current source, and a load48that is electrically driven by the power source46by way of the switching circuit42. In the embodiment, the load48would be the electrical heaters and/or electrical controllers of the deicer18. The strike detector40supplies a control signal to the switching circuit42to force the switching circuit42to discontinue the supply of electrical power to the load48upon the occurrence of certain events. The switching circuit42can include a clamping operation to shut off power from the power source46to the load48.

Referring now toFIG. 5, the strike detector40and a portion of the switching circuit42is schematically shown. As will be appreciated, the strike detector40is configured to generate an output to invoke termination of the supply of electrical power to a load upon the occurrence of certain events. These events include a loss of electrical continuity from one end of the trip line20to another end of the trip line20, contact or electrical bridging of the trip line20with a high voltage line or potential (e.g., a 115 volt electrical conductor of a deicer), or contact or electrical bridging of the trip line20to electrical ground (e.g., the aircraft structure). Therefore, as used herein, “disruption” (and other forms of the root word “disrupt”) of the trip line20or of the conductive path of the trip line20is meant to include any of the foregoing scenarios. However, for simplicity of the description herein, the strike detector will be described in the example context of when an impact results in loss of continuity from the first end24to the second end26.

A sensing voltage, such as a DC voltage (VDC), is applied across the trip line20. For example, the sensing voltage can be coupled to a first end24of the trip line20through a series resistor R1and series diode D1and a second26end of the trip line20can be coupled to ground through the series combination of Zener diode D2, series resistor R2, and Zener diode D3/resister R3, which are connected in parallel. The gate of a power MOSFET Q1(e.g., model IRF7490 available from International Rectifier) can be connected to a node between resistors R2and R3. The drain of MOSFET Q1can be connected between resistors R4and R5, which form a voltage divider between the second end26and ground. The source of the MOSFET Q1can be connected to ground. In parallel with resistor R5can be Zener diode D4.

The gate of a power MOSFET Q2(e.g., model IRF7490) can be connected to the node between resistors R4and R5. The source of the MOSFET Q2can be grounded. The drain of MOSFET Q2provides an output signal from the strike detector40, which can be considered a strike override signal. If the trip line20is not disrupted (e.g., the trip line20is intact and has electrical continuity from the first end24to the second end26), the strike override signal will indicate that no impact related damage to at least the trip line20is present. In one embodiment, the strike override signal can be logical high when the trip line20is not disrupted. If the trip line20is disrupted (e.g., the trip line20is not intact and is without electrical continuity from the first end24to the second end26as caused by an event such as a strike by a bird or other foreign object), the strike override signal will indicate that impact related damage to at least the trip line20is present. In one embodiment, the strike override signal can be logical low when the trip line20is disrupted.

The strike override signal can be input to the switching circuit42that includes a switch54for controlling the application of electrical power from the load power source46to the load48. The switch54can be, for example, a solid state relay assembly for switching AC power to the load. Suitable switches implemented as a switching assemblies are disclosed in U.S. Patent Application Publication Nos. 2004/0212940 and 2004/0222701, the entire disclosures of which are herein incorporated by reference in their entireties. In those switching assemblies, application of power is supplied to the load (e.g., the load48) using series switches implemented with power FET type devices. The power FETs are gated with latches (e.g., flip-flops) that are controlled, in part, by an optically isolated power-on signal. For example, when it is desired that power should be applied to the load, the power-on signal can be logical high and when it is desired that power should not be applied to the load, the power-on signal can be logical low. The power-on signal can be regulated by any number and/or combination of manners, including, for example, a cockpit switch, the over-current detector44, a temperature controller switch (e.g., thermostat), a deicer controller forming part of the deicer18and so forth.

To effectuate additional control of the switching circuit42with the strike override signal, a logical AND operation can be carried out to combine the power-on signal with the strike override signal using an AND gate56to generate a switch control signal. If appropriate, the power-on signal, the strike override signal and/or the switch control signal can be inverted to attained a desired logical state of the signals. Of course, it will be recognized that the power-on signal, the strike override signal and/or the switch control signal need not be implemented as digital logic values and combining the power-on signal and the strike override signal can be carried out in any suitable manner or not combined, if appropriate (e.g., the signals can be used to gate separate FETs where the source of one is connected to the drain of another).

The switch control signal from the AND gate56can be used as a control signal for the switch54to selectively control the application of electrical power from the load power source46to the load48. For example, the switch control signal can be used to control an optically isolated FET that controls the latches in the solid state relay assembly of the above-mentioned U.S. Patent Application Publication Nos. 2004/0212940 and 2004/0222701. As will be appreciated, if the strike override signal indicates that the trip line20is not disrupted, the switch54will operate in a normal manner based on the state of the power-on signal. But if the strike override signal indicates that the trip line20is disrupted, the switch54will turn off power to the load48if in a presently applied state and not turn on power to the load48if called for by the power-on signal at some point in the future. Tests have shown that when the strike override signal is generated using the strike detector40illustrated inFIG. 4and the switch54is implemented with the solid state relay assembly of the above-mentioned U.S. patent application publications, a desired speed of discontinuing the application of single phase or multi-phase power to the load48can be achieved.

In another embodiment, the voltage at the first end24can be used as the basis for the strike override signal. For instance, the strike detector40can include the application of a DC voltage to first end24of the trip line20via a resistor (e.g., R1) and the second end26can be coupled to ground. When the trip line20is not disrupted, the voltage at the first end will be the ground potential (e.g., zero volts) or close to the ground potential depending on the resistance of the trip line20, connectors, lead wires, etc. When the trip line20is disrupted, the voltage at the first end24will rise. In one arrangement, a logic inverter can be connected to generate an output based on the voltage at the first end24to generate the strike override signal at the output of the inverter. This signal can be combined with the power-on signal in, for example, the manner described above.

Similar to how the strike override signal is generated, the switch54can be implemented in any suitable manner. For example, the switch54can be or include a solid state relay assembly as described above, one or more FETs gated in accordance with the strike override signal (sometimes referred to as a crowbar), a microprocessor controller, or any other discrete or programmable component or combination of components.

In addition to generating a strike override signal used to invoke the disconnection of the electrical power to a particular system or otherwise shut off an electrical, hydraulic or mechanical system, a strike warning signal can be generated. The strike warning signal can be made available to cockpit instrumentation to alert the pilot, can be input to a flight controller and/or used in any appropriate manner to regular events occurring with respect to the aircraft. In the illustrated embodiment, the strike warning signal can be generated by connecting the gate of a power MOSFET Q3(e.g., model IRF7490) to the node between resistors R4and R5. The source of the MOSFET Q3can be grounded and the drain of MOSFET Q3provides the warning signal in similar manner to the way MOSFET Q2generates the strike override signal.

The present invention is described in the example context of shutting off electrical power to a deicer18on a wet wing12in the event that the wing is struck by a bird or other object. However, the present invention is not limited to a deicer and/or a wing, and can be used on any impact-susceptible part of an aircraft. For example, the trip line20and/or object-strike protection circuit38can be used in an engine rotor explosion impact area to shut down a system near a fuel container (e.g., a fuel tank, a fuel cell, a fuel conduit, etc.). Moreover, the trip line20and/or object-strike protection circuit38can be used even if interaction with fuel is not an issue, such as, for example, to prevent impact-affected electrical lines from being shorted to the frame of the aircraft.

One may now appreciate that the present invention provides an electrical trip line for an impact-susceptible part of an aircraft that allows quick discontinuation of electric power supply to avoid an undesired voltage potential. Although the invention has been shown and described with respect to certain embodiments, it is evident that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such alterations and modifications and is limited only by the scope of the following claims.