Aircraft floor incorporating a ground plane

A system for shielding of at least one component (28) within an aircraft (10) includes a floor panel disposed at least partially between joists (38) supporting a floor (30) within the aircraft and a ground plane (44) connected to a bottom surface of the floor panel. The ground plane extends at least partially between adjacent joists. At least one bracket (52) electrically connects the ground plane to at least one of the joists.

FIELD OF THE INVENTION

The present invention concerns a construction incorporating a protective ground plane into a floor panel of an aircraft, a bracket for connecting the ground plane to a joist supporting a floor panel in an aircraft, and a system combining the ground plane and bracket for grounding the ground plane within an aircraft. The ground plane is contemplated to provide isolation from electromagnetic and radio frequency sources, among other types of electrical protection.

DESCRIPTION OF THE RELATED ART

In the construction of traditional aircraft, it has been the practice of aircraft manufacturers to place wire bundles at strategic locations within the fuselage of the aircraft. The wire bundles include wires that provide power to various devices located on the aircraft. The wires also carry electrical signals between devices located on the aircraft and, therefore, provide electronic communication between those various devices.

As should be apparent to those skilled in the art, it is known to provide electrical shielding for the wire bundles within the aircraft. Electrical protection (or shielding) encompasses insulating (or isolating) wires from interference from one or more sources of electromagnetic and/or radio frequency sources.

With respect to electromagnetic and radio frequency transmissions, it should be apparent that there are various sources of potentially interfering signals. Interference may be generated by components that are part of the aircraft. Separately, passengers and crew members may bring devices on board the aircraft (i.e., cellular telephones, tablets, computers, etc.) that may generate electromagnetic (“EM”) and/or radio frequency (“RF”) signals that have the potential to interfere with signals transmitted along the wire bundles. A third potential source of EM and RF signals are those generated exterior to the aircraft. For example, communications towers (i.e., cellular towers, radio towers, etc.) may generate signals that are of sufficient strength to interfere with aircraft systems, even from an appreciable distance.

A simple way to provide electrical protection for one or more wires is to position the wires near to a grounded, electrically conductive substrate. Typically, the substrate is made from metal, because metal materials are excellent conductors. In addition, metal materials function well to protect electrical signals in wires from being influenced by EM and RF interference.

As should be apparent to those skilled in the art, the skin of traditional aircraft is made from aluminum or an alloy of aluminum. Being made from metal, the skin of the traditional aircraft offers a convenient surface against which wire bundles may be positioned. As a result, it has been common practice to lay wire bundles adjacent to (or in close proximity) to the interior surface of the skin of the aircraft. By positioning the wire bundles adjacent to the skin of the aircraft, the traditional aircraft designer has been able to provide EM and RF shielding for those wires.

More and more, modern aircraft incorporate non-metallic components. For example, modern aircraft incorporate carbon fiber composite materials into at least some of the panels forming the skin and other structural components.

Carbon fiber composite materials are not particularly conductive when compared to metals. As a general rule, carbon fiber materials are about one thousand times (1000×) less conductive than metals. Carbon fiber materials, therefore, are inadequate for shielding wires from EM and RF interference.

As should be apparent, with the substitution of carbon fiber composite materials for metal in modern aircraft, the skin of the aircraft may no longer act as a suitable ground location, to establish an EM shield and/or RF shield for the wire bundles positioned adjacent thereto.

Separately, given the space requirements in aircraft, it is contemplated that the wire bundles may not be placed adjacent to the skin of the aircraft, even where the aircraft is made entirely from metal.

As a result, a need has developed for a light-weight EM/RF shield for electrical wire bundles disposed within the aircraft, regardless of the positioning of the wire bundles in the aircraft. In other words, a need developed a way to shield electrical wires regardless of their position within the aircraft.

SUMMARY OF THE INVENTION

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

In one contemplated embodiment, the present invention provides a system for shielding of at least one component within an aircraft. The system includes a floor panel disposed at least partially between joists supporting a floor within the aircraft, a ground plane connected to a bottom surface of the floor panel, the ground plane extending at least partially between adjacent joists, and at least one bracket electrically connecting the ground plane to at least one of the joists.

In another embodiment of the system of the present invention, the ground plane shields the at least one component from at least one of electromagnetic and radio frequency interference.

It is contemplated that the ground plane is made of a plate of electrically conductive material and at least one hole provided in the plate to lighten the total weight of the plate. The hole is sized for shielding of the at least one component, accommodating at least one of frequency and wavelength of impingent radiation upon the at least one component.

It is calculated that the hole is no more than about 1/10thof the size of a minimum wavelength of the impingent radiation.

The bracket that forms a part of the invention includes a body defining a first end and a second end. The first end connects to a ground plane and the second end connects to the joist. At least one first fastener connects the first end to the ground plane. At least one second fastener connects the second end to the joist. A spacer connects to the first end, establishing a contact surface between the spacer and the ground plane. A seal surrounds the spacer.

Another embodiment of the present invention provides a ground plane for shielding of at least one component within an aircraft. The ground plane includes a plate of electrically conductive material, and at least one hole provided in the plate to lighten the total weight of the plate. The hole is sized for shielding of the at least one component, accommodating at least one of frequency and wavelength of impingent radiation upon the at least one component. As noted, the hole may be no more than about 1/10thof the size of a wavelength of the impingent radiation. In one embodiment, the hole is about 1.2 inches in diameter.

It is contemplated that the ground plane shields the at least one component from at least one of electromagnetic and radio frequency interference.

The component may be a wire bundle disposed adjacent to the ground plane.

The ground plane is contemplated to be made from metal.

The present invention also provides a bracket for connecting a ground plane to a joist for shielding of at least one component within an aircraft. The bracket includes a body defining a first end and a second end, wherein the first end connects to a ground plane and wherein the second end connects to the joist, at least one first fastener connecting the first end to the ground plane, at least one second fastener connecting the second end to the joist, a spacer connected to the first end, establishing a contact surface between the spacer and the ground plane, and a seal surrounding the spacer.

The spacer is contemplated to be made from an electrically conductive material.

The bracket is contemplated to be made from metal.

The spacer is contemplated to include a peripheral portion and an inner portion with a thickness greater than that of the peripheral portion.

The seal surrounding the spacer is contemplated to be made from an elastomeric material.

Further aspects of the present invention will be made apparent form the paragraphs that follow.

DETAILED DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

The present invention will now be described in connection with one or more embodiments thereof. The discussion of any particular embodiment is not intended to be limiting of the present invention. To the contrary, the discussion of selected 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.

The present invention will now be discussed in the content of the construction of an aircraft10, such as the one illustrated in the perspective view provided inFIG. 1.

FIG. 1is a perspective illustration of an aircraft10to which the present invention applies. The aircraft10includes a fuselage12defining a forward end14and a rear (or aft) end16. Two wings18,20extend laterally from the fuselage12. A tail section22is attached to the rear end16of the aircraft. As should be apparent to those skilled in the art, the wings18,20and the tail section22incorporate multiple control surfaces that are responsible for flying characteristics and flight operations of the aircraft10. Two engines24,26are suspended from and connect to the wings18,20, as illustrated.

As discussed above, all aircraft10include wire bundles28that perform at least two primary functions. Some of the wires in the wire bundles transfer power to one or more of the operational components within the aircraft10. Others of the wires transmit electrical signals that are processed by one or more of the devices on the aircraft10. As a result, it is desirable to provide shielding so that the wires in the wire bundles28are insulated (or isolated) from EM and RF influences. As should be apparent to those skilled in the art, EM and RF influences (among other variables) may impact upon the performance and/or operation of the wires in the wire bundles28in addition to interfering with one or more components on board the aircraft.

FIG. 2is a graphical cross-section of a conventional aircraft10. A floor30of the cabin32is provided for reference. As illustrated, wire bundles28are positioned adjacent to the interior surface34of the fuselage12. The wire bundles28extend along the length of the aircraft10from a position near to the front end14to a position near to the rear end16. As noted above, in the conventional aircraft10, the skin36of the aircraft10is made from a metal, in particular aluminum or an aluminum alloy. The metal skin36, therefore; provides a convenient location for the placement of the wire bundles28thereagainst. The skin36of the aircraft10provides shielding from EM and RF sources.

As also discussed above, modern aircraft are, more and more, incorporating carbon fiber composite panels in lieu of aluminum parts. Carbon fiber panels, while lighter and (in some configurations) stronger than their aluminum counterparts, are not particularly conductive. As a general rule, carbon fiber composite components are about 1000 times less conductive than metals. As a result, carbon fiber components do not adequately shield the wire bundles28from EM and/or RF sources.

FIG. 3is a graphical cross-section of the aircraft illustrated inFIG. 1. This cross section is provided to assist with a discussion of specific aspects of the present invention.

As should be apparent to those skilled in the art, the floor30is supported by joists38, which are spaced from one another and extend along the longitudinal axis of the aircraft10. Cross joists (not shown in this illustration) extend laterally between the sides of the fuselage12and connect the joists38together to form a checkerboard lattice under the floor30within the cabin32of the aircraft10.

As should be apparent to those skilled in the art, the joists38typically are made from metal, such as aluminum or an aluminum alloy. Being made from metal, the joists38provide at least a limited degree of grounding and protection against EM and RF interference. However, the distance40between the joists38exceeds the protective distance42established by the joists38. As such, any wire bundles28that are positioned adjacent to the joists38will not benefit from protection from EM and RF interference because some portion of the wire bundles28will lie outside of the protective distance42established by the joists38.

FIG. 4illustrates one aspect of the present invention. Specifically, to provide protection from EM and RF interference (hereinafter referred to as “electrical protection”), the aircraft10of the present invention incorporates ground planes44that are positioned beneath the floor30, above and adjacent to respective ones of the wire bundles28.

The ground planes44are contemplated to be made from a conductive material, such as metal. In the illustrated embodiment, the ground planes are made from aluminum or an aluminum alloy. The ground planes have a width46that is at least as wide as the adjacent wire bundle28. The wire bundles28are positioned sufficiently close to the ground planes44so that they benefit from the electrical protection established by the ground planes44.

In the contemplated embodiment, the ground planes44have a width46that is greater than the widths of the wire bundles28disposed adjacent thereto. In an alternative embodiment, the ground planes44may have widths that are equal to the widths of the wire bundles28. In a third contemplated embodiment, the ground planes44may have widths46that are less than the widths of the bundles28positioned adjacent thereto. In this third embodiment, it is understood that the ground planes44establish electrical protection that extends a distance from the edges thereof, just as the joists38establish a protective distance42therefrom. Relying on this aspect of the ground planes44, it is contemplated that the ground planes44need not be as wide as the adjacent wire bundles28.

As also is illustrated inFIG. 4, the ground planes44are contemplated to be interposed between the floor30(which is made from a matrix of floor panels30that are connected to the joists38and the cross joists (not shown in this view)) and the wire bundles28. In an alternative embodiment, it is contemplated that the ground planes44may be positioned within the aircraft10such that the wire bundles28are positioned between the ground planes40and the floor30without departing from the scope of the present invention.

It is noted that the floor panels30provide a convenient location for the location of the ground plane44of the present invention. In addition, the floor panels30are removable from the joists and cross joists48, thereby providing access to any wire bundles28positioned thereunder.

FIG. 5is a perspective view showing one contemplated embodiment of the present invention. The perspective is taken from a vantage point beneath the floor30of the aircraft10looking upwardly at the bottom surface of one or more of the floor panels30. The joists38are visible in this illustration, as is at least one of the cross joists48. The ground plane44is visible beneath the floor30.

As should be apparent to those skilled in the art, the weight of components in the aircraft10is always a concern for aircraft designers. Specifically, aircraft designers endeavor to lighten aircraft components so that they present a minimal weight addition to the aircraft10while performing their intended function(s). This design consideration applies to the ground plane44, just as it does with other aircraft components.

So that the ground plane44offers sufficient electrical protection but does not add unnecessarily to the overall weight of the aircraft10, the ground plane44is constructed to be thin and to include a plurality of holes50cut therethrough. With respect to the thickness of the ground plane44, one embodiment contemplates that the ground plane44will be quite thin. For example, the ground plane44may be only ten one thousandths of an inch (0.01 inch; 0.254 mm) thick. It is contemplated that the ground plane44may be made thicker or thinner without departing from the scope of the present invention.

Being so thin, the ground plane44is more like an aluminum foil, rather than a rigid plate of metal. Being so thin, the ground plane44preferably is affixed to the bottom surface of the floor30so that the ground plane44is not easily torn or damaged. It is contemplated that the ground plane44may be applied to the floor30as a coating during manufacture of the floor30. Alternatively, the ground plane44may be affixed to the bottom of the floor30via any suitable adhesive or other suitable attachment means.

As noted above, the ground plane44includes a plurality of holes50cut therethrough. The holes50have a diameter that does not exceed a maximum size required for electrical protection.

One embodiment of the present invention contemplates that the holes50will have diameters of about 1.2 inches (3.05 cm). It is also contemplated that the distance between holes50will not be less than 1.2 inches (3.05 cm). This specific distance was selected based on calculations associated with the frequency and wavelength of the types of electrical threats anticipated to be present in the aircraft10(i.e., electronic devices) or in the environment through which the aircraft10travels (i.e., communications towers).

It is noted that the holes are sized to accommodate specific wavelength (and frequencies) of EM and RF interference. The holes50have a diameter that is approximately 1/10 of the length of the shortest wavelength of the types of interfering EM and/or RF radiation that is anticipated to impinge thereon. Finally, while circular holes are illustrated, the holes50may have any shape without departing from the scope of the present invention.

As should be apparent, the ground plane44of the present invention is not considered to be limited to this particular construction. Holes50with a larger or smaller diameter may be employed without departing from the scope of the present invention. Moreover, the distance between the holes may be larger or smaller than 1.2 inches (3.05 cm) without departing from the scope of the present invention.

In one contemplated embodiment, the ground plane44does not include any holes50. While this adds weight to the aircraft10, a solid ground plane44offers maximum shielding protection to any wire bundles28positioned adjacent thereto.

So that the ground plane44is electrically grounded within the aircraft10, the ground plane44is connected to the joists38(or, alternatively, the cross joists48) via one or more brackets52. The brackets52are connected to the ground plane44and the floor30at a first end54, via one or more fasteners56. The brackets52are connected to the joists38at a second end58via one or more fasteners60.

At the first end54, the bracket52and the ground plane44establish a metal-to-metal contact to ensure a reliable electrical connection therebetween. Similarly, at the second end58, the bracket52and the joist38present a metal-to-metal contact to ensure a reliable, electrical contact therebetween. As such, the ground plane44is suitably grounded via the network of supports made up of the joists38and the cross joists48(among other components in the aircraft10).

InFIG. 5, floor fasteners62also are illustrated. The floor fasteners62removably connect the floor panels30to the joists38and the cross joists48. As should be apparent to those skilled in the art, the floor panels30are designed to be removable so that personnel may access the components (including the wire bundles28) that are located beneath the floor30. Such access may be needed, for example, to perform maintenance or repairs on the aircraft10.

So that the floor panels30may be disengaged from the brackets52, the fasteners56also are removable. The second ends58of the brackets52are not contemplated to be removed easily from the joists38(or cross-joists48) unless there is a need to replace one or more of the brackets52. In other words, the brackets52in this embodiment are contemplated to remain affixed to the joists38after removal of one or more of the floor panels30.

FIG. 6is a cross-sectional view of a portion of the ground plane44of the present invention, the cross section being taken through one of the fasteners56. The perspective is looking toward one of the joists38from the fastener56.

The fastener56extends through the floor panel30and the first end54of the bracket52. The fastener56is surrounded by a seal64that extends through the floor panel30. The seal64helps to protect the electrical connection between the ground plane44and the bracket52.

The first end54of the bracket52includes a spacer66that is connected to and extends upwardly from a top surface of the bracket52. The spacer66includes a thin, peripheral portion68and a thicker, inner portion70.

The peripheral portion68of the spacer66is penetrated by at least one fastener72that connects the spacer66to the first end54of the bracket52. As should be apparent, the illustrated embodiment provides room for two fasteners72. While two fasteners72are illustrated, a larger or a fewer number may be used without departing from the scope of the present invention.

The spacer66is electrically connected to the first end54of the bracket via a metal-to-metal contact. As should be apparent, the spacer66is made from metal, such as aluminum. However, the spacer66may be made from any other suitable, conductive material without departing from the scope of the present invention. The inner portion70of the spacer66establishes an electrical contact74between the bracket52and the ground plane44. A seal76, made from an elastomeric material such as rubber, surrounds the spacer66. In addition to the seal64, the seal76helps to protect the electrical contact between the spacer66and the ground plane44. Specifically, the seal76discourages moisture and debris from entering the space around the spacer64and, thereby, protects the electrical connection74between the spacer66and the ground plane44.

FIG. 7is a perspective illustration of the bracket52illustrated inFIGS. 5 and 6. The perspective is taken from above the bracket52with the floor panel30having been removed.

FIG. 8is a graphical top view of two contemplated installations of the ground plane44according to the present invention.

On the right hand side ofFIG. 8, the ground plane44extends nearly the full distance between adjacent joists38. On the left hand side, the ground plane44extends partially between two adjacent joists38.

It is noted that the embodiment provided on the left hand side ofFIG. 8includes extensions78that extend outwardly from the ground plane44to the edge of the floor plate30on which the ground plate44is disposed. The brackets52connect to the extensions78in the same manner as the brackets52connect to the ground plane44. Specifically, the brackets52connect to the extensions78via one or more fasteners56.

In another contemplated embodiment, it is contemplated that the extensions78may be substituted by elongated brackets (not shown) that extend from the joists38(and/or cross-joists48) to the ground plate44. The elongated brackets (no shown) are, therefore, considered to fall within the scope of the present invention.

In both embodiments, it is contemplated that four brackets52will connect between the joists38and the ground planes44at roughly the corners of the ground planes44. This arrangement is preferred because the arrangement provides acceptable redundancy. Moreover, by connecting the brackets at the corners of the ground planes44, a better distribution of electrical protection is established. As should be apparent, however, a larger or a smaller number of brackets52may be employed without departing from the scope of the present invention.

As should be apparent from the foregoing, the present invention is contemplated to be disposed in an aircraft10. The aircraft10may be made entirely with a metal skin, with a partially metal skin with nonmetal portions, or entirely from a non-metallic material such as carbon fiber composite.

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.