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Title:
SELF-LIMITING, ELECTRICALLY-POWERED HEATING ELEMENT FOR AN AIRCRAFT
Document Type and Number:
WIPO Patent Application WO/2019/119151
Kind Code:
A1
Abstract:
A heating element disposable on an aircraft component includes first and second conductors connectible to an electrical power source, a first plurality of conductive elements connected to the first conductor and extending a first predetermined distance to the second conductor, a second plurality of conductive elements connected to the second conductor and extending a second predetermined distance to the first conductor, and a resistive element establishing an electrical path between the first conductor and the first plurality of conductive elements and the second conductor and the second plurality of conductive elements. The resistive element generates heat when an electric current flows through the electrical path. The resistive element is a positive temperature coefficient resistive element that is thermally self-limiting, thereby establishing a predetermined maximum heat output for heating the aircraft component.

Inventors:
VERRELLI, Danilo (1430 Port-Alfred, Laval, Québec H7E 4R2, H7E 4R2, CA)
Application Number:
CA2018/051650
Publication Date:
June 27, 2019
Filing Date:
December 21, 2018
Export Citation:
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Assignee:
BOMBARDIER INC. (400 Côte Vertu Road West, Dorval, Québec H4S 1Y9, H4S 1Y9, CA)
International Classes:
H05B3/00; B64D15/12; B64D47/00
Foreign References:
US20110297665A12011-12-08
US20110240751A12011-10-06
US20100213189A12010-08-26
Attorney, Agent or Firm:
LACHERÉ, Julien (BCF LLP, 1100 Rene-Levesque Blvd. West,Suite 250, Montreal Québec H3B 5C9, H3B 5C9, CA)
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Claims:
What is claimed is:

1. A heating element disposable on an aircraft component, comprising:

a first conductor connectible to an electrical power source;

a second conductor connectible to the electrical power source;

a first plurality of conductive elements connected to the first conductor and extending a first predetermined distance to the second conductor;

a second plurality of conductive elements connected to the second conductor and extending a second predetermined distance to the first conductor; and

a resistive element establishing an electrical path between the first conductor and the first plurality of conductive elements and the second conductor and the second plurality of conductive elements,

wherein the resistive element generates heat when an electric current flows through the electrical path, and

wherein the resistive element is a positive temperature coefficient resistive element that is thermally self-limiting, thereby establishing a predetermined maximum heat output for heating the aircraft component.

2. The heating element of claim 1, further comprising:

a substrate,

wherein the resistive element is disposed atop the substrate, and

wherein the first conductor, the first plurality of conductive elements, the second conductor, and the second plurality of conductive elements are disposed atop the resistive element.

3. The heating element of claim 1, further comprising:

a substrate,

wherein the resistive element is disposed atop the substrate, and

wherein the first conductor, the first plurality of conductive elements, the second conductor, and the second plurality of conductive elements also are disposed atop the substrate and are co-planar with the resistive element.

4. The heating element of claim 1, wherein the first conductor is parallel to the second conductor.

5. The heating element of claim 4, wherein the first plurality of conductive elements is parallel to the second plurality of conductive elements.

6. The heating element of claim 5, wherein the first conductor is perpendicular to the first plurality of conductive elements and the second conductor is perpendicular to the second plurality of conductive elements.

7. The heating element of claim 1, wherein:

a gap is established between the first plurality of conductive elements and the second plurality of conductive elements,

the gap also is established between first free ends of the first plurality of conductive elements and the second conductor, and

the gap also is established between second free ends of the second plurality of conductive elements and the first conductor.

8. The heating element of claim 7, wherein:

the resistive element establishes a serpentine path between the first conductor, the first plurality of conductive elements, the second conductor, and the second plurality of conductive elements.

9. The heating element of claim 8, wherein the gap is uniform throughout the serpentine path.

10. The heating element of claim 2, wherein the substrate is constructed from a flexible material.

11. The heating element of claim 10, wherein the flexible material is selected from a group comprising plastics, polymers, rubbers, resins, metals, ceramics, composites.

12. The heating element of claim 1, wherein the resistive element is constructed from a flexible material.

13. The heating element of claim 12, wherein the flexible material is selected from a group comprising plastics, polymers, rubbers, resins, metals, ceramics, composites.

14. The heating element of claim 13, wherein the flexible material includes a dopant to enhance electrical properties of the resistive element.

15. The heating element of claim 14, wherein the dopant is selected from a group comprising carbon, graphite, and one or more metals.

16. The heating element of claim 1, wherein the first conductor, the second conductor, the first plurality of conductive elements, and the second plurality of conductive elements are constructed from a flexible material.

17. The heating element of claim 16, wherein the flexible material is selected from a group comprising plastics, polymers, rubbers, resins, metals, ceramics, composites.

18. The heating element of claim 1, wherein the heating element is disposed on a door.

19. The heating element of claim 18, wherein the door is at least one selected from a group comprising a forward passenger door, a rearward passenger door, and an emergency exit door.

20. The heating element of claim 1, wherein the heating element is disposed on an interior surface of an air duct.

21. The heating element of claim 1, wherein the heating element is disposed on at least a portion of a tail section of an aircraft for de-icing.

22. The heating element of claim 1, wherein the heating element is disposed on at least a portion of a leading edge of a wing of an aircraft for de-icing.

23. The heating element of claim 1, wherein the heating element is disposed on at least a portion of a trailing edge of a wing of an aircraft for de-icing.

24. The heating element of claim 1, wherein the heating element is disposed on at least a portion of an engine cowl for de-icing.

25. The heating element of claim 1, wherein the heating element is disposed on at least a portion of a floor panel within the aircraft.

26. The heating element of claim 1, wherein the heating element is disposed around a drain to prevent the drain from becoming clogged with ice.

Description:
SELF-LIMITING, ELECTRICALLY-POWERED HEATING ELEMENT FOR AN AIRCRAFT

Cross-Reference to Related Application(s)

[0001] The present application claims priority to U.S. Provisional Patent Application

No. 62/609,527, filed December 22, 2017, the entirety of which is incorporated herein by reference.

Field of the Invention

[0002] The present invention concerns a self-limited, electrically-powered heating element for a vehicle, such as an aircraft. While the present invention is directed to a device for providing heat at discrete locations on an aircraft, the present invention is not limited solely to the embodiments described herein.

Description of the Background and Related Art

[0003] As should be apparent to those skilled in the art, it may be desirable to provide supplemental heating at discrete locations on a vehicle to address specific temperature differentials at those discrete locations.

[0004] In the context of aircraft, because aircraft operate between considerable temperature extremes, there exists an enhanced need for providing supplemental heating at specific locations on the aircraft.

[0005] In the prior art, it is known to employ a supplemental heater where additional heat is desired or required.

[0006] Supplemental heaters, however, are associated with undesirable qualities.

Specifically, supplemental heaters are large, bulky, and consume considerable energy when providing heat at the discrete locations. As a result, they are not suitable for some locations where size, weight, and safety are concerned. In addition, supplemental heaters require separate controls, typically provided by a controller dedicated to operation of the supplemental heater. The controller (or controllers) must be accommodated in the aircraft design, adding to the weight and complexity of the aircraft. [0007] While some solutions have been proposed by the prior art, a need exists for improved solutions.

Summary of the Invention

[0008] The present invention addresses one or more of the deficiencies with respect to the prior art.

[0009] The present invention provides a heating element disposable on an aircraft component. The heating element includes a first conductor connectible to an electrical power source, a second conductor connectible to the electrical power source, a first plurality of conductive elements connected to the first conductor and extending a first predetermined distance to the second conductor, a second plurality of conductive elements connected to the second conductor and extending a second predetermined distance to the first conductor, and a resistive element establishing an electrical path between the first conductor and the first plurality of conductive elements and the second conductor and the second plurality of conductive elements. The resistive element generates heat when an electric current flows through the electrical path. The resistive element is a positive temperature coefficient resistive element that is thermally self-limiting, thereby establishing a predetermined maximum heat output for heating the aircraft component.

[0010] In one contemplated embodiment, the heating element also includes a substrate.

The resistive element may be disposed atop the substrate. The first conductor, the first plurality of conductive elements, the second conductor, and the second plurality of conductive elements also are contemplated to be disposed atop the resistive element.

[0011] In another variation, it is contemplated that the heating element will include a substrate with the resistive element being disposed atop the substrate. In this embodiment, the first conductor, the first plurality of conductive elements, the second conductor, and the second plurality of conductive elements also are contemplated to be disposed atop the substrate and to be co-planar with the resistive element.

[0012] It is contemplated, for example, that the first conductor may be parallel to the second conductor.

[0013] Still further, the first plurality of conductive elements may be parallel to the second plurality of conductive elements. [0014] The first conductor may be perpendicular to the first plurality of conductive elements and the second conductor may be perpendicular to the second plurality of conductive elements.

[0015] In another contemplated embodiment, a gap may be established between the first plurality of conductive elements and the second plurality of conductive elements. The gap also may be established between first free ends of the first plurality of conductive elements and the second conductor. Still further the gap may be established between second free ends of the second plurality of conductive elements and the first conductor.

[0016] It is contemplated that the resistive element may establish a serpentine path between the first conductor, the first plurality of conductive elements, the second conductor, and the second plurality of conductive elements.

[0017] It is also contemplated that the gap will be uniform throughout the serpentine path.

[0018] In one embodiment, the substrate may be constructed from a flexible material that encompasses, but it not limited to, plastics, polymers, rubbers, resins, metals, ceramics, composites.

[0019] Similarly, the resistive element may be constructed from a flexible material. The flexible material also may be selected from plastics, polymers, rubbers, resins, metals, ceramics, composites.

[0020] The resistive element also may be constructed from a flexible material, including but not limited to plastics, polymers, rubbers, resins, metals, ceramics, composites. For the resistive element, the flexible material may include a dopant to enhance electrical properties of the resistive element. Dopants include, but are not limited to, carbon, graphite, and one or more metals.

[0021] Next, it is contemplated that the first conductor, the second conductor, the first plurality of conductive elements, and the second plurality of conductive elements may be constructed from a flexible material such as plastics, polymers, rubbers, resins, metals, ceramics, composites.

[0022] The heating element may be positioned in a large variety of locations on an aircraft that include, but are not limited to a door, a forward passenger door, a rearward passenger door, an emergency exit door, an interior surface of an air duct, a portion of a tail section of an aircraft for de-icing, a portion of a leading edge of a wing of an aircraft for de- icing, a portion of a trailing edge of a wing of an aircraft for de-icing, a portion of an engine cowl for de-icing, a portion of a floor panel within the aircraft, and around a drain to prevent the drain from becoming clogged with ice.

[0023] Further aspects of the present invention will be made apparent from the paragraphs that follow.

Brief Description of the Drawing(s)

[0024] The present invention will now be described in connection with the drawings appended hereto, in which:

[0025] Fig. 1 is a graphical, perspective view of one traditional installation of an in-line heater for an air duct in an aircraft, where the in-line heater is electrically driven and provides supplemental heating;

[0026] Fig. 2 is a graphical, top view of a first embodiment of a heating element according to the present invention;

[0027] Fig. 3 is a graphical, cross-sectional, side view of the first embodiment of the present invention shown in Fig. 2;

[0028] Fig. 4 is a graphical, cross-sectional, side view of a second embodiment of a heating element according to the present invention;

[0029] Fig. 5 is a graphical, cross-sectional, side view of the second embodiment of the heating element according to the present invention illustrated in Fig. 4, where the substrate is affixed to a surface;

[0030] Fig. 6 is a graphical, cross-sectional, side view of the second embodiment of the heating element according to the present invention illustrated in Fig. 4, where the substrate is affixed to a surface via an adhesive;

[0031] Fig. 7 is a graphical, perspective view of one contemplated environment for the heating element according to the present invention; and

[0032] Fig. 8 is a graphical, top view of an aircraft, illustrating possible locations and environments for the heating element according to the present invention. Detailed Description of Embodiment^ s) of the Invention

[0033] The present invention will now be described in connection with one or more embodiments thereof. The discussion of any one particular embodiment is not intended to be limiting of the present invention. To the contrary, any discussion of specific embodiments is intended to exemplify the breadth and scope of the present invention. As should be apparent to those skilled in the art, variations and equivalents of the embodiment s) described herein may be employed without departing from the scope of the present invention. Those variations and equivalents are intended to be encompassed by the scope of the present patent application.

[0034] Aspects of the present invention are described in connection with one or more configurations for an aircraft. While emphasis is placed on an aircraft and the applicability of the heating element of the present invention to an aircraft, the present invention is not limited to use on an aircraft. The heating element of the present invention may be employed on other vehicles, including, but not limited to, busses, trains, boats, helicopters, automobiles, and the like.

[0035] As a preliminary matter, it is noted that the design and construction of an aircraft involves numerous parameters. Among them, aircraft designers endeavor to employ components that enhance the safety and comfort of the passengers and crew on board the aircraft. Aircraft designers also consider the reliability of the components and the systems used on the aircraft. Still further, aircraft designers endeavor to reduce the overall weight of the aircraft, because lighter aircraft are more fuel efficient than heavier aircraft of the same type, as a general rule. Safety and low weight are two parameters that underlie the present invention, as discussed below.

[0036] Fig. 1 is a perspective view of a conventional heater 10. In the illustrated example, the heater 10 is disposed intermediate to a first end 12 and a second end 14 of an air duct 16. The heater 10 includes a housing 18 that is offset from a centerline of the air duct 16, which is common for this type of installation.

[0037] The housing 18 encompasses electrically-powered heating elements (not shown) that heat the air as it passes from the first end 12 to the second end 14 of the air duct 16. Power is provided to the heating elements from a power source 20, via wires 22, 24. A controller 26, connected to the conventional heater 10 via one or more wires 28, provides the operating instructions for the conventional heater 10 within the housing 18.

[0038] As should be apparent to those skilled in the art, there are a few detriments associated with conventional heaters 10. In the context of the design parameters listed above, conventional heaters 10 tend to be heavy, thereby adding to the weight of the aircraft. In particular, conventional heaters 10 may weight up to 4 lbs. (1.81 kg) each. The weight of a conventional heater 10 may be attributed to elements such as required fuses, thermostats, and overtemperature switches. In addition, conventional heaters 10 are known to have high failure rates due to the mechanical nature of the heat transfer. Still further, conventional heaters 10 also are known to have high failure rates as a result of applicable safety protections. And, conventional heaters 10 must be connected to a controller 26 that regulates the power provided to the conventional heaters 10.

[0039] To address one or more of the deficiencies associated with conventional heaters

10 and the prior art, the present invention provides heating elements 30, 62 that are light in weight, simple to install, and thermally self-limiting. Specifically, the heating elements 30, 62 of the present invention are considerably lighter in weight than conventional heaters 10. As a result, the heating elements 30, 62 of the present invention do not burden the aircraft with excess weight overall. Next, the heating elements 30, 62 of the present invention satisfy safety regulations, because the heating elements 30, 62 are thermally self-limiting, which prevents overheating of the heating elements 30, 62. Because the heating elements 30, 62 of the present invention provide a low cross-sectional profile, the heating elements 30, 62 may be installed in locations on an aircraft previously unavailable to supplemental heating devices. In addition, the heating elements 30, 62 are easy to install and maintain by comparison with conventional heaters 10. And, the heating elements 30, 62 do not require separate controllers for their operation. The heating elements 30, 62 also offer other advantages that will become apparent in the paragraphs that follow.

[0040] Fig. 2 is a top view of a non-limiting example of the first embodiment of the heating element 30 according to the present invention.

[0041] As illustrated in Fig. 2, the heating element 30 is defined by an outer perimeter 32 with a square shape. It is noted, however, that the square shape is merely exemplary of the myriad of shapes that are possible for the heating element 30. Without limiting the present invention, the heating element 30 may be round, elliptical, ovoid, triangular, polygonal, or amorphously shaped.

[0042] The heating element 30 includes a substrate 34. The substrate 34 is contemplated to be made from a flexible material onto which the remaining elements are disposed. Without limiting the present invention, flexible materials for the substrate 34 include plastics, polymers, rubbers, resins, metals, ceramics, composites, or the like. The substrate 34 may be made from any flexible material as required or desired. Flexible materials are contemplated for the substrate 34 of the heating element 30 so that the heating element 30 may be affixed to virtually any surface, regardless of the contours and features presented by that surface.

[0043] A resistive element 36 is disposed atop the substrate 34. The resistive element 36 is contemplated to generate heat when an electric current passes through the resistive element 36. As such, the resistive element 36 is contemplated to be made from materials that generate heat when provided with electrical power. In addition, the material selected for the resistive element 36 also is contemplated to be flexible. Like the substrate 34, flexible materials for the resistive element 36 include plastics, polymers, rubbers, resins, metals, ceramics, composites, or the like. As noted in connection with the substrate 34, it is contemplated that the heating element 30 may be affixed to surfaces with complex geometries.

[0044] With continued reference to Fig. 2, two conductors 38, 40 are disposed atop the substrate 34. The conductors 38, 40 are contemplated to be made from a flexible material, such as plastics, polymers, rubbers, resins, metals, ceramics, composites, or the like. Where the conductors 38, 40 are made from metal, a thin metal foil may be employed. As before, the conductors 38, 40 are flexible to permit installation of the heating element 30 on a wide variety of surfaces and in a wide variety of environments.

[0045] The conductors 38, 40 connect to pads 42, 44 to which wires, such as the wires

22, 24, may be connected to provide power from the power source 20. It is noted that the pads 42, 44 may be omitted from the heating element 30 without departing from the scope of the present invention.

[0046] As also illustrated in Fig. 2, the first conductor 38 includes a first plurality of conductive elements 46 extending from the first conductor 38 toward the second conductor 40. Similarly, the second conductor 40 includes a second plurality of conductive elements 48 extending from the second conductor 40 toward the first conductor 38. The first plurality of conductive elements 46 and the second plurality of conductive elements 48 are separated from one another by a gap 50. The resistive element 36 extends within the gap 50 and converts the electrical energy to heat when power is applied to the pads 42, 44 and the conductors 38, 40.

[0047] In the example illustrated in Fig. 2, each of the first plurality of conductive elements 46 are equidistantly-spaced from each of the second plurality of conductive elements 48 by the gap 50. In addition, the first free ends 52 of the first plurality of conductive elements 46 are spaced apart from the second conductor 40 by the same gap 50. As is apparent from Fig. 3, the second free ends 54 of the second plurality of conductive elements 48 also are spaced from the first conductor 38 by a distance equal to the gap 50.

[0048] The gap 50 is contemplated to establish a serpentine path 56 between the conductors 38, 40 and the conductive elements 46, 48. With a uniformly-thick gap 50, it is contemplated that the resistance between the conductors 38, 40 and the conductive elements 46, 48 will be constant. At least in part due to the uniformity of the gap 50, which contains the resistive element 36, and taking into account the fundamental equation V = I · R, the heating element 20 is contemplated to generate a uniform heating profile along the entire length of the serpentine path 56. In other words, with the illustrated construction, hot spots may be avoided.

[0049] It is noted that the resistive element 36 may be constructed with a non-uniform composition. Here, some areas of the resistive material 36 may generate more heat than other areas. Such a construction may be required for specific environments, as should be apparent to those skilled in the art.

[0050] With continued reference to Fig. 2, the resistive element 36 is contemplated to be a positive temperature coefficient resistive element and therefore thermally self-limiting. “Self- limiting” refers to a characteristic whereby the resistive element 36 attains a maximum heat output when the resistive element 36 receives an electric current equal to or greater than a predetermined threshold. For example, the resistive element 36 may be made from a combination of materials such that the application of an electric current in excess of 1 A will not result in a further increase the heat produced by the resistive element 36. As a further example, the resistive element 36 may be made from materials that generate no greater than 40 °C (104 °F). As such, in this theoretical example, the resistive element 36 would produce heat at a constant temperature of 40 °C (104 °F) when the electric current is equal to or greater than 1 A. The resistance of the resistive element 36 goes up from a low initial resistance as the temperature of the resistive element 36 goes up. The low initial resistance results in a rapid generation of heat. However, at some point in the temperature increase, the corresponding resistance increase reduces the heat generation produced by the resistive element 36. Consequently, an equilibrium is reached, thus resulting in the self-limiting characteristic of the resistive element 36.

[0051] The“self-limiting” aspect of the resistive element 36 provides a number of desirable attributes to the heating element 30. First, the heating element 30 satisfies safety protocols, because the resistive element 36 is made from a material with a maximum temperature output. Being self-limiting, the heating element 30 may be constructed to have a maximum heat output that is below any critical temperatures (i.e., melting points) of other materials and components that are disposed adjacent to the heating element 30. Second, the heating element 30 may be designed and constructed for a particular purpose, because the material selected for the resistive element 36 may be limited to a particular temperature. Here, for example, a first heating element 30 with a maximum temperature of 40 °C (104 °F) may be used in one part of the cabin of the aircraft. A second heating element 30 with a maximum temperature of 50 °C (122 °F) may be employed elsewhere in the aircraft. Third, the self-limiting feature removes the need to incorporate components such as safety fuses, controllers, set-point potentiometers, etc., into the heating element 30 and/or its power and control system(s). Additionally, it is contemplated that the material selected for the resistive element 36 may be doped with one or more elements and/or compounds to enhance the electrical properties of the resistive element 36. For example, dopants are known to change the resistive properties of materials. Suitable dopants include, but are not limited to, carbon, one or more metals, and the like. For example, the resistive element 36 may be made from a polymer doped with graphite.

[0052] With continued reference to Fig. 2, the first conductor 38 is parallel to the second conductor 40. The first plurality of conductive elements 46 are parallel to the second plurality of conductive elements 48. As illustrated the first conductor 38 is perpendicular to the first plurality of conductive elements 46. Similarly, the second conductor 40 is perpendicular to the second plurality of conductive elements 48. While this is one contemplated arrangement, the first conductor 38, the second conductor 40, the first plurality of conductive elements 46, and the second plurality of conductive elements 48 may take any shape and orientation while remaining within the scope of the present invention. [0053] Fig. 3 is a graphical, cross-sectional, side view of the first embodiment of the heating element 30 shown in Fig. 2. As should be apparent to those skilled in the art, the graphical illustration of the heating element 30 is not drawn to scale. The cross-section is taken along the line A-A in Fig. 2.

[0054] In this first embodiment, the heating element 30 is constructed such that the resistive element 36 is disposed as a continuous layer atop the substrate 34. In this embodiment, the resistive element 36 defines a resistive element perimeter 58. As is apparent from Fig. 2, the resistive element 36 is deposited onto the substrate 34 in the shape of a square. As with the substrate 34, the resistive element 36 may be deposited to exhibit a square shape. As discussed in connection with the substrate 34, the shape of the resistive element 36 may be altered as required or desired. It is contemplated that the resistive element 36 may be may be round, elliptical, ovoid, triangular, polygonal, or amorphously shaped.

[0055] With continued reference to Fig. 3, the first plurality of conductive elements 46 and the second plurality of conductive elements 48 are spaced between one another by the gap 50. However, the first plurality of conductors 46 and the second plurality of conductors 48 need not be disposed on the resistive element 36 in the pattern shown. Those skilled in the art may employ any number of patterns, as required or desired.

[0056] In addition, this cross-section shows the second conductor 40. The illustration also shows the second pad 44 that is connected to the second conductor 40.

[0057] As also shown in Fig. 3, when a current is applied to the first plurality of conductive elements 46, the current passes through the resistive element 36 to the second plurality of conductive elements 48 via an electrical path 60, thereby generating heat.

[0058] Fig. 4 is a graphical, cross-sectional, side view of a second embodiment of a heating element 62 according to the present invention.

[0059] Here, the heating element 62 is configured so that the resistive element 36, the first conductor 38, the first plurality of conductive elements 46, the second conductor 40, and the second plurality of element 48 are disposed on the substrate 34. As such, the resistive element 36, the first conductor 38, the first plurality of conductive elements 46, the second conductor 40, and the second plurality of element 48 are disposed on the substrate 34 so that they are co-planar, forming a single layer atop the substrate 34. Here, it is contemplated that a current will travel between the first plurality of conductive elements 46 and the second plurality of elements 48 along an electrical path 64 that extends directly through the adjacent portions of the resistive element 36.

[0060] Fig. 5 is a graphical, cross-sectional, side view of the second embodiment of the heating element 62 according to the present invention illustrated in Fig. 4. In this view, the substrate 34 is affixed to a surface 66.

[0061] Fig. 6 is a graphical, cross-sectional, side view of the second embodiment of the heating element 62 according to the present invention illustrated in Fig. 4, where the substrate 34 is affixed to a surface 68 via an adhesive 70. As also shown, in this contemplated orientation, the top of the heating element 62 is adjacent to the surface 66, which may facilitate heat transfer to the surface 66, as required or desired.

[0062] In one contemplated embodiment, the resistive element 36, 62 the first and second conductors 46, 48, the first plurality of conductive elements 46, and the second plurality of elements 48 may be applied directly to a surface, such as the surfaces 66, 68. For example, the heating element 30, 62 may be printed directly onto the surface 66, 68. In one embodiment, the conductive elements and the resistive elements are made of inks that are printable. In one embodiment, the conductive elements are made of a silver ink and the resistive elements are made from a LOCTITE® ECI 8001 ink that is a positive temperature coefficient ink. Other methods for applying the heating elements 30, 62 should be apparent to those skilled in the art.

[0063] Fig. 7 is a graphical illustration of one contemplated location for placement of the heating element 30, 62 of the present invention. Specifically, Fig. 7 illustrates an air duct 74 that is circular in cross-section. The heating element 30, 62 may be rolled into a cylindrical shape and placed within the air duct 74 such that the heating element 30, 62 is in direct contact with the interior surface 76 of the air duct 74.

[0064] The heating element 30, 62 may be secured to the interior surface 76 of the air duct 74 by any fastener including, but not limited to adhesives, screws, bolts, nuts, welds, or the like. Alternatively, the heating element 30, 62 may be secured within the air duct 74 by nothing more than a friction fit. However, it is contemplated that the heating element 30, 62 will be secured within the air duct 74 with a suitable adhesive. As noted, the heating element 30, 62 may be printed directly onto the interior surface 76 of the air duct 74.

[0065] In an alternative construction, the heating element 30, 62 may be affixed to the exterior surface 78 of the air duct 74. As with the prior embodiment, the heating element 30, 62 may be secured to the exterior surface 78 of the air duct 74 by any fastener including, but not limited to adhesives, screws, bolts, nuts, welds, or the like. As noted, the heating element 30, 62 may be printed directly onto the exterior surface 78 of the air duct 74.

[0066] Fig. 7 also illustrates two wires 22, 24 that connect the heating element 30, 62 to a power source 20. The power source 20 may provide a direct current or an alternating current to the heating element 30, 62 so that heat may be generated thereby. In the illustrated embodiment, power is provided by a 12 VDC source on board the aircraft.

[0067] Fig. 8 is a graphical, top view exemplary of an aircraft 80 that is contemplated to receive one or more of the heating elements 30, 62 of the present invention.

[0068] As should be apparent from the foregoing, the heating element 30, 62 of the present invention may be positioned on the aircraft 80 at a number of different locations due to, among other things, its low weight, thin profile, and flexibility.

[0069] For example, the heating element 30, 62 may be installed on a forward passenger door 82, an emergency exit door 84, or a rear passenger door 86. The doors 82, 84, 86 to an aircraft 80 includes a number of components that facilitate opening and closing of the door 82, 84, 86. Those same components assure an airtight seal between the door 82, 84, 86 and the aircraft 80. As a result of the design of modern doors 82, 84, 86, there is little room to accommodate or to install dedicated heaters similar to the one illustrated in Fig. 1.

[0070] Still further, the heating elements 30, 62 may be installed on the tail section 88, the leading edges 90 of the wings, the trailing edges 92 of the wings, and/or the engine cowls 94. Each of these areas on the aircraft 80 may require de-icing (also referred to as anti-icing). The heating element 30, 62 of the present invention may provide that heating alone or may be used in combination with other heating systems aboard the aircraft 80.

[0071] Finally, the heating element 30, 62 of the present invention may be used in other areas on the aircraft 80, such as in or on the floor panels within the cabin of the aircraft. Still further, the heating element 30, 62 of the present invention may be disposed around a drain to prevent the drain from becoming clogged with ice.

[0072] As noted above, the embodiment s) described herein are intended to be exemplary of the wide breadth of the present invention. Variations and equivalents of the described embodiment s) are intended to be encompassed by the present invention, as if described herein.