Window assembly for aircraft fuselage

A window assembly for an aircraft fuselage comprises an exterior transparent panel and an interior transparent panel positioned in an opening of the fuselage. At least one of the transparent panels may be relatively lightweight and the exterior transparent panel may be spaced apart from and in overlying relationship with the interior transparent panel. To ameliorate pressure build up in the spaced apart area, a pressure modulator, such as a vent, may be provided.

FIELD OF INVENTION

This invention relates to window assemblies and more particularly to window assemblies used in an aircraft fuselage.

BACKGROUND

Aircraft typically include openings in a fuselage for a plurality of windows. Commercial airplanes, for example, include a plurality of windows within the fuselage for passengers to look through during flight. These windows often employ heavy support structures to secure them to the fuselage. Since minimizing the weight of an aircraft advantageously increases fuel efficiency and the cargo load that can be carried by the aircraft, it would be desirable to utilize a relatively lightweight window assembly.

SUMMARY OF THE INVENTION

The present invention relates to an improved window assembly for use with an aircraft fuselage. The window assembly comprises at least one transparent panel. The at least one transparent panel may comprise a density between about 0.025 pounds per cubic inch to about 0.50 pounds per cubic inch and weigh between about 1.0 pound and 3.0 pounds. The at least one transparent panel may be constructed of a transparent thermoplastic polymer, such as polycarbonate, polyacrylate or mixtures thereof and may be positioned in general alignment with an external surface of the aircraft fuselage. As used herein, the term “panel” means any structure that can be inserted into an opening in an aircraft fuselage.

In one embodiment, the window assembly of the present invention comprises an exterior transparent panel covering at least a portion of an opening in the aircraft fuselage, an interior transparent panel positioned in a spaced apart relationship with the exterior transparent panel and overlying at least a portion of the exterior transparent panel. The spaced apart relationship defines a space between the exterior and interior transparent panels. The window assembly further comprises a pathway in communication with the space and the atmosphere outside the aircraft fuselage. The pathway may travel through a pressure modulator or vent comprising a deflectable center portion and one or more slits openable to an area the aircraft fuselage. As used herein, the term pathway means an opening or area through which air may travel and the term vent means a device with a closed position and an open position, where the open position allows the escape of a gas, such as air, from one area to another.

In another embodiment, the window assembly of the present invention comprises an exterior transparent panel covering at least a portion of an opening in the aircraft fuselage, an interior transparent panel overlying at least a portion of the exterior transparent panel and a vent secured to at least one of the exterior and interior transparent panels.

In still another embodiment, the window assembly comprises an exterior transparent panel covering at least a portion of an opening in the aircraft fuselage and an interior transparent panel overlying at least a portion of the exterior transparent panel, the interior transparent panel being constructed to withstand a greater load bearing force than the exterior transparent panel.

DETAILED DESCRIPTION

The window assembly of the present invention comprises at least one transparent panel associated with an opening in an aircraft fuselage. In certain embodiments, the transparent panel is relatively lightweight, constructed of a material comprising a density between about 0.025 pounds per cubic inch to about 0.60 pounds per inch and more particularly between about 0.040 pounds per cubic inch to about 0.045 pounds per inch. In other embodiments, the window assembly comprises an exterior transparent panel and an interior transparent panel, one or both of which cover at least a portion of an opening in an aircraft fuselage.

Referring now toFIGS. 1 and 2, one embodiment of the window assembly10of the present invention is shown. The window assembly10ofFIGS. 1 and 2comprises exterior transparent panel12, interior transparent panel14, pressure modulator16, pathway18, retaining fitting20, retaining frame21, inner seal22and outer seal23. As best shown byFIG. 2, window assembly10may be secured to opening24in aircraft fuselage26.

Exterior transparent panel12may comprise an external surface positioned in general alignment with a portion of an external surface of aircraft fuselage26. This transparent panel is typically aerodynamic and constructed of a transparent thermoplastic polymer. The thermoplastic polymer may be relatively lightweight, exhibiting a density between about 0.025 pounds per cubic inch to about 0.60 pounds per cubic inch and more particularly between about 0.040 pounds per cubic inch to about 0.045 pounds per cubic inch. For example, polycarbonates, thermoplastic polymers or copolymers of acrylic acid, methacrylic acid, esters of these acids or acrylonitrile, as well as other suitable polymers known to those of skill in the art may be employed.

Depending on its dimensions, therefore, the total weight of exterior transparent panel12may be between about 1.0 pound and 3.0 pounds and more particularly between about 1.25 pounds and 1.75 pounds. Transparent panel12, which is typically oval in shape, may comprise first diameter d between about 10.0 inches to about 15.0 inches and second diameter d′ between about 18.0 inches to about 24.0 inches and more particularly first diameter d between about 12.0 inches and about 14.0 inches and second diameter d′ between about 20.0 inches and 22.0 inches. The configuration and lightweight aspect of exterior transparent panel12of this embodiment advantageously provides a weight savings aboard the aircraft.

Interior transparent14panel may overly at least a portion of exterior transparent panel12. In certain embodiments, interior transparent panel14may be constructed to withstand a greater load bearing force than exterior transparent panel12. For example, interior transparent panel12can withstanding a load bearing force of between about 14.0 pounds per square inch and about 20.0 pounds per square inch, while exterior transparent panel12may be constructed to withstand a load bearing force of up to about 4.0 pounds per square inch and more particularly up to about 2.5 pounds per square inch. Further, transparent panels12and14may be positioned in a spaced apart relationship with one another, defining space15, as shown inFIGS. 4A and 4B.

During flight, a pressure differential within space15and an area outside space15, such as the atmosphere outside the fuselage26, may arise. For example, at high altitudes, a pressure of about 15.0 pounds per square inch exists inside space15while pressures of about 2.0 pounds per square inch exists outside aircraft fuselage26. Since the pressure differential can lead to breakage of the transparent panels as well as other unwanted effects, the present invention further provides effective ways to ameliorate the aforementioned pressure differential.

In one embodiment, shown inFIG. 4B, a pathway18in communication with space15and with the atmosphere of fuselage26is provided. Pathway18allows pressure built up inside space15to release into an area of lower pressure (e.g., the atmosphere outside the aircraft), as shown by the arrows inFIG. 4B. Pathway18may include a pressure modulator16for regulating the release of pressure from space15. Pressure modulator is typically positioned on exterior transparent panel12. As used herein, the term pressure modulator means any device or structure that allows for the release of pressure from one area to another.

For example, a vent may serve as pressure modulator16. As shown inFIG. 3, vent16may comprise annular surface30with deflectable center32, which comprises one or more slits34. The one or more slits34are predisposed to a closed position until a pressure differential occurs from one side of vent16to the other, causing deflectable center32to push the one or more slits34into their open position. Under these circumstances, the pressure in space15may be released into an area outside an external surface of aircraft fuselage26, thereby creating approximate pressure equalization on both sides of vent16. Vent16can be engineered to open at predetermined pressure differentials to minimize pressure loads on exterior and interior transparent panels12and14.

Vent16may be secured to one of exterior and interior transparent panels12and14in a variety of ways. Vent16may, for example, be self-supporting within a small aperture33positioned in exterior transparent panel12. Additionally or alternatively, vent16may comprise a retaining housing35for securing vent16within the small aperture33. Small aperture33is typically positioned near the top of exterior transparent panel12(but may be positioned anywhere on panel) and is adapted to receive vent16and/or retaining housing35.

Vent16and/or retaining housing35may also incorporate a fail-safe feature. In one embodiment, retaining housing35is configured to fail at a predetermined pressure build-up. In the event vent16becomes plugged and fails to appropriately vent pressure, the predetermined pressure build-up would blow out the retaining housing35from the small aperture in exterior transparent panel12, taking vent16with it. In this way, approximate pressure equalization on both sides of exterior transparent panel12helps prevent exterior transparent panel12from shattering and departing aircraft fuselage26. Further, vent26may easily be replaced after landing.

Retaining fitting20, retaining frame21and outer seal23may be designed to work together. As shown inFIGS. 2 and 5, retaining fitting20may comprise a plurality of preformed openings36, channel37and spring clips39. Retaining frame21may comprise corresponding hooks40, which are adapted to mate with the spring clips39to secure retaining fitting20to frame21. Finally, outer seal23may comprise a plurality of projections41for insertion into channel37.

The various components of window assembly10can be made in different ways. Exterior transparent panel12can be injected molded, compression molded or machined and polished. One or both of exterior and interior transparent panels12and14may be constructed of tempered glass or the transparent thermoplastic polymer mentioned hereinabove. Retaining fitting20and outer seal22are also typically injection molded. As shown inFIGS. 1 and 2, interior transparent panel14and retaining fitting20are formed with a plurality of preformed openings36spaced circumferentially around the perimeters. One embodiment of vent16is available from Liquid Molding Systems of Midland Michigan Vent retaining housing35can be bonded to vent16or comprise a ring fitting or holding vent16. Vent retaining housing35can be made by injection molding.

To assemble window assembly10, preformed openings36in interior transparent panel14, retaining fitting20and aircraft fuselage26are aligned and secured together with fastening elements38. Inner seal22is positioned within retaining fitting20, with exterior transparent panel12placed over inner seal22. Retaining frame21may next be positioned over inner seal22, with hooks40of retaining frame21engaging spring clips39of retaining fitting20. Finally, outer seal23is placed over retaining frame21so that its projections41are positioned within channel37. Additional details concerning how to assemble the window assembly of the present invention may be found in the co-owned, co-pending application, entitled “Window Assembly Retaining System.”

Variations, modifications and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, the invention is in no way limited by the preceding illustrative description.