This application relates to seals and, more particularly, to fire seals, such as fire seals for use in a fire zone of an aircraft.
Aircraft engines are typically housed in a nacelle. A pylon extends from the nacelle to couple the engine to the aircraft. As one example, the pylon may couple the engine to a wing of the aircraft (e.g., the engine may be suspended below the wing). As another example, the pylon may couple the engine directly to the fuselage of the aircraft (e.g., the engine may be mounted to the side of the fuselage proximate the rear of the fuselage).
In modern aircraft, various steps are typically taken to inhibit the spread of flames from the engine to the wings and fuselage of the aircraft. For example, all structural interfaces within the engine/pylon assembly are typically sealed with fireproof (or fire-resistant) material to eliminate gaps through which flames may propagate.
The structural interfaces of an aircraft vary with manufacturing tolerances and many structural interfaces are dynamic, thereby rendering many structural interfaces of an aircraft difficult to seal. For example, the interface between the pylon fairing and the nozzle of the aircraft engine can be quite dynamic as a result of significant temperature fluctuations. Rubber seals, such as silicone rubber seals, have been used to seal structural interfaces in aircraft, but high operating temperatures limit the use of rubber seals. Metallic feather seals have been used to seal structural interfaces that are too hot for rubber seals. However, metallic feather seals are difficult to install, present durability issues that increase maintenance costs, and typically must be manufactured using relatively high-cost techniques, such as hydroforming.
Accordingly, those skilled in the art continue with research and development efforts in the field of aircraft fire seals.
In one embodiment, the disclosed fire seal may include an acute bend having a first end portion and a second end portion, a first engagement extension extending from the first end portion of the acute bend, and a second engagement extension extending from the second end portion of the acute bend, wherein the second engagement extension is at an acute angle relative to the first engagement extension to define a partially enclosed volume between the first engagement extension and the second engagement extension.
In another embodiment, the disclosed sealed assembly may include a first member, a second member spaced apart from the first member, and a fire seal positioned between the first member and the second member, the fire seal including an acute bend having a first end portion and a second end portion, a first engagement extension extending from the first end portion of the acute bend, and a second engagement extension extending from the second end portion of the acute bend, wherein the second engagement extension is at an acute angle relative to the first engagement extension to define a partially enclosed volume between the first engagement extension and the second engagement extension.
In another embodiment, the disclosed aircraft may include an engine having a nozzle, a pylon having a pylon fairing, and a fire seal positioned between the nozzle and the pylon fairing, the fire seal including an acute bend having a first end portion and a second end portion, a first engagement extension extending from the first end portion of the acute bend, and a second engagement extension extending from the second end portion of the acute bend, wherein the second engagement extension is at an acute angle relative to the first engagement extension to define a partially enclosed volume between the first engagement extension and the second engagement extension.
In yet another embodiment, the disclosed method for forming a seal may include the steps of (1) providing a sheet of stock material; (2) cutting the sheet to form a silhouette; (3) bending the silhouette in a straight bending machine to form an acute bend having a first engagement extension extending from a first end portion of the acute bend and a second engagement extension extending from a second end portion of the acute bend; and (4) bending the second engagement extension in the straight bending machine to form a bend therein.
Other embodiments of the disclosed fire seal for an aircraft will become apparent from the following detailed description, the accompanying drawings and the appended claims.
Referring to
As best shown in
The magnitude of the bend angle ΘB and corresponding acute angle ΘA may vary without departing from the scope of the present disclosure. Indeed, selection of the specific bend angle ΘB and corresponding acute angle ΘA may be a design consideration. As one general, non-limiting example, the bend angle ΘB may range from about 100 degrees to about 180 degrees, which may yield an acute angle ΘA between the first and second engagement extensions 14, 16 ranging from about 80 degrees to about 0 degrees. As another general, non-limiting example, the bend angle ΘB may range from about 135 degrees to about 170 degrees, which may yield an acute angle ΘA between the first and second engagement extensions 14, 16 ranging from about 45 degrees to about 10 degrees. As one specific, non-limiting example, the bend angle ΘB may be about 160 degrees, which may yield an acute angle ΘA between the first and second engagement extensions 14, 16 of about 20 degrees.
Still referring to
Thus, in one particular expression, the radius R of the acute bend 12 may depend on the overall size of the fire seal 10, such as the width W of the first engagement extension 14. The width W may be the linear distance the first engagement extension extends from the first end portion 18 (
Referring again to
Optionally, the second engagement extension 16 may include a bend 24 that directs the distal end 26 of the second engagement extension 16 toward the first engagement extension 14. The bend 24 may be an obtuse bend (shown) or an acute bend (not shown). While only one bend 24 is shown in
The first and second engagement extensions 14, 16 may be integral with the acute bend 12 (e.g., formed as a single monolithic body). However, it is also contemplated that one or more of the first engagement extension 14, the second engagement extension 16 and the acute bend 12 may be formed as a separate piece and then connected to the other pieces, such as by welding, press-fitting or with mechanical fasteners.
The fire seal 10 may be formed from various materials without departing from the scope of the present disclosure. Use of metallic materials, polymeric materials and composite materials are contemplated.
In one particular construction, the fire seal 10 may be formed from a metal or metal alloy capable of withstanding aircraft engine fire zone temperatures, such as temperatures ranging from about 500° F. to about 1500° F., while remaining generally springy and resilient. As one general, non-limiting example, the fire seal 10 may be formed from steel. As one specific, non-limiting example, the fire seal 10 may be formed from stainless steel. As another specific, non-limiting example, the fire seal 10 may be formed from a precipitation-hardened stainless steel, such as 17-7 PH® stainless steel available from AK Steel Corporation of West Chester, Ohio.
Optionally, one or more functional coatings or treatments may be applied to a surface of the fire seal 10 (e.g., to the outer surface of the second engagement extension 16). As one example, a wear layer, such as a wear-resistant fabric layer, may be applied to the fire seal 10. As another example, a flame/thermally-resistant spray coating may be applied to the fire seal 10.
In one particular implementation, the fire seal 10 may be formed as a layered structure 40, as best shown in
Referring now to
The slots 50 formed in the first layer 42 (
The fire seal 10 may be formed from a flat sheet of stock material (e.g., stainless steel). The sheet of stock material may be cut (e.g., stamped) to the desired silhouettes (e.g., two flat sheets that will form the two layers 42, 44 (
As shown in
Significantly, the fire seal 10 may maintain the seal between the first and second members 30, 32 even as the spacing between the first and second members 30, 32 varies (e.g., increases or decreases). For example, when the second member 32 moves toward the first member 30, thereby reducing the spacing therebetween (e.g., a load L is applied), the fire seal 10 may compress about the acute bend 12 in a spring-like manner. Then, when the second member 32 moves away from the first member 30 (e.g., the load L is reduced or removed), the tension accumulated in the acute bend 12 may cause corresponding expansion that maintains the seal between the first and second members 30, 32.
The disclosed fire seal 10 may be used in various applications. While an aerospace application is described herein, other applications, such as automobile applications, are also contemplated.
Referring to
As best shown in
Referring to
As shown in
The second engagement extension 16 of the fire seal 10 may protrude upward into touching engagement with the pylon fairing 124. The spring-like nature of the fire seal 10 may maintain touching engagement with the pylon fairing 124 even as the gap spacing of the gap 126 varies. Therefore, the disclosed fire seal 10 may substantially seal the gap 126 between the nozzle 116 and the pylon fairing 124.
Thus, the nozzle 116 of the aircraft 100 may correspond to the first member 30 shown in
The acute bend 12 of the fire seal 10 may protrude toward the aft end 114 (
Accordingly, the disclosed fire seal 10 may provide a relatively low cost, durable solution for sealing structural interfaces in high temperature environments. The fire seal 10 may be much more flexible and compliant than traditional seals. Therefore, the fire seal 10 may experience less wear and tear, and may be fabricated straight and then assembled onto a curved surface. Manufacturing costs may be reduced by forming the fire seal 10 as one long part, rather than multiple parts.
Referring to
In one particular implementation, the biasing element 1008 may be a compression spring, as shown in
Examples of the disclosure may be described in the context of an aircraft manufacturing and service method 200, as shown in
Each of the processes of method 200 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of venders, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
Apparatus and methods embodied herein may be employed during any one or more of the stages of the aircraft manufacturing and service method 200. For example, components or subassemblies corresponding to component/subassembly manufacturing 208, system integration 210, and or maintenance and service 216 may be fabricated or manufactured using the disclosed fire seal 10 (or fire seal 1000). Also, one or more apparatus examples, method examples, or a combination thereof may be utilized during component/subassembly manufacturing 208 and/or system integration 210, for example, by substantially expediting assembly of or reducing the cost of an aircraft 202, such as the airframe 218. Similarly, one or more of system examples, method examples, or a combination thereof may be utilized while the aircraft 202 is in service, for example and without limitation, to maintenance and service 216.
The disclosed system and method are described in the context of an aircraft; however, one of ordinary skill in the art will readily recognize that the disclosed service system may be utilized for a variety of different components for a variety of different types of vehicles. For example, implementations of the embodiments described herein may be implemented in any type of vehicle including, e.g., helicopters, passenger ships, automobiles and the like.
Although various embodiments of the disclosed fire seal for an aircraft have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.
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Number | Date | Country | |
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