Connector and aircraft structure

Abstract

The invention provides a connector and an aircraft structure. In one aspect, a connector (1) for connecting a fluid flow conduit to a fuel stringer conduit is disclosed. The connector (1) comprises a body (7) having an internal passage (17) for the passage of fluid between a first opening (9) and a second opening (13) of the body (7). A flange (19) surrounds the first opening (9), the flange (19) being configured for insertion into a hole formed in a wall of the fuel stringer duct. An outer surface (191) of the flange (19) is provided with a first sealing member (20) surrounding the flange (19), the first sealing member (20) being configured to form a seal between the outer surface (191) of the flange (19) and an inner surface of a bore formed in a wall of the fuel stringer duct.

Description

Technical Field

[0001] The present disclosure relates to a connector for connecting a fuel stringer conduit to another fluid flow conduit. In particular, the present disclosure relates to a connector configured to form a seal between a flange of the connector and an inner surface of a hole in the fuel stringer conduit. The present disclosure also relates to an aircraft structure including the fuel stringer conduit and the connector. Background Art

[0002] It is known to use aircraft hat-section wing stringers, also known as omega stringers, as ducts to conduct fluids, both liquids and gases, along the span direction of the wing. Stringers are reinforcing members fixed to the wing skin and extend from the wing root to the wing tip in the span direction of the wing. The cross-sectional shape of the hat stringer is defined by two spaced coplanar flanges for attaching the stringer to the reinforced panel, a pair of spaced upright webs attached to the inner edges of the flanges, and a crown bridged across the distal ends of the webs. Such stringers, when attached to the reinforced panel, form a closed channel capable of conducting fluid along its length.

[0003] In particular, for modern civil airliners that use the space in the wing for fuel tanks, this hat-shaped cross-section stringer can be used to conduct fuel, fuel vapor or air along the span of the wing between the fuel tanks. This stringer has been called a fuel stringer duct (FSD), and is particularly used to discharge air from a central fuel tank and one or more wing boxes to a buffer tank that is generally located in the outer part of the wing. Air enters the FSD in a given box via a bellmouth or a discharge float valve, which is located on the inner side of the top of the box and close to the top. The bellmouth or float valve is usually connected to the FSD by a certain length of pipe.

[0004] One known method of attaching a tube connector, typically an elbow connector, to a FSD is by bonding. If the wing cover is made of carbon fiber reinforced plastic (CFRP), the FSD may comprise the same material and be co-cured against the cover to form a unitary structure. In this case, the connector used to connect the tube to the carbon fiber FSD is shaped to fit around the hat-section FSD and is attached to the FSD by co-curing in place or by using an adhesive. However, the use of such a bonded connection between the connector and the FSD means that the connector cannot be easily removed and replaced if damaged. Such a connector is easily damaged because it protrudes from the FSD.

[0005] Another known method of attaching a pipe connector to an FSD involves the use of a connector such as that disclosed by EP3590825A1, in which the connector has a bridge that bridges over the FSD and covers an aperture in the wall of the FSD. The bridge is configured so that the connector can be attached to a panel on each side of the FSD by fasteners passing through the bridge. In this arrangement, a seal is provided between an outer surface of the FSD, such as the upper surface of the crown, and a surface of the connector. However, because there may be some variability, albeit small, in the dimensions of the composite FSD after cure, the outer surface of the FSD that forms the sealing surface is provided with a layer of sacrificial material that can be machined away during appropriate post-cure to provide the FSD with an outer surface that fits perfectly with the connector. Therefore, the FSD may have to be post-cured to ensure a fluid-tight seal between the FSD and the connector.

[0006] The present invention seeks to alleviate one or more of the above problems.Alternatively or additionally, the present invention seeks to provide an improved connector for connecting a FSD to another fluid flow conduit. Summary of the invention

[0007] According to a first aspect, the present invention provides a connector for connecting a fluid flow pipe to a fuel stringer pipe, the connector comprising a body, the body comprising: a first opening, the first opening being located on a first face; a second opening, the second opening being located on a second face, the second face being configured to be connected to the fluid flow pipe; an internal passage, the internal passage being used for fluid passage between the first opening and the second opening; and a flange, the flange surrounding the first opening located on the first face, the flange being configured to be inserted into a hole formed in a wall of the fuel stringer pipe, wherein an outer surface of the flange is provided with a first sealing member surrounding the flange, the first sealing member being configured to form a seal between the outer surface of the flange and an inner surface of the hole formed in the wall of the fuel stringer pipe.

[0008] The first face may be configured to be positioned to abut a surface of the FSD. The first face may alternatively or additionally be configured to be positioned in a spaced relationship from the surface of the FSD. The second face may be configured to be positioned to abut a fluid flow conduit. The flange may extend in a direction away from the first face. An outer surface of the flange may be in a plane perpendicular to a plane defined by the first face.

[0009] The connector according to the present invention is configured so that when connected to the FSD, the first sealing member forms a seal between the flange of the connector and the inner surface of the hole in the FSD. The hole in the FSD can be molded or post-cured with a size having a relatively low tolerance. Because the hole in the FSD can be manufactured with a consistent size and with an inner wall having a suitable surface finish, the inner wall of the hole provides an ideal surface for forming a seal.

[0010] The first sealing member may be spaced apart from the first face of the body. The first sealing member may be spaced apart from the first face of the body by about 2 mm to 6 mm. The first sealing member may be spaced apart from the first face of the body by about 3 mm to 5 mm.

[0011] In some embodiments, the first sealing member is an o-ring. The outer surface of the flange may be formed with a groove extending around the periphery of the flange, and the o-ring may be located in the groove. The o-ring may be formed of a polymer. The polymer may be fluorosilicone or any other suitable polymer. The groove may be spaced apart from the first face of the connector.

[0012] The connector may include a bridging member located on the opposite side of the first opening, the bridging member extending from the body, the bridging member being configured to bridge on the FSD on each side of the FSD. The bridging member may include a foot for fixing the connector to a surface on each side of the FSD. There may be two bridging members. Each bridging member may extend in a direction away from the first face of the body. The body may form a crown between the two bridging members. Each bridging member may include a web located between the foot and the body. The bridging member may be configured to maintain the body in a fixed position relative to the FSD by fixing the connector to a surface of the aircraft structure on each side of the FSD.

[0013] Compared to prior art connectors that include a bridging member that forms a seal between the face of the connector and the outer surface of the FSD, the connector including the bridging member according to the first aspect of the present invention is less sensitive to manufacturing tolerances of the FSD. For example, slight variations in the height of the crown between different FSDs should not affect the ability of the connector to form a seal with the inner surface of the bore of each of the FSDs. This is because small deviations in the height of the crown of the FSD will only change the position where the sealing member engages the inner wall of the bore, and will not move the sealing surface (i.e., the inner wall of the bore) away from the first sealing member.

[0014] The connector may be provided with a hole for fastening the connector to the FSD. The hole may be provided through the body of the connector. Where present, the hole may be provided in the foot of the bridging member. Thus, the connector may be configured to be releasably fastened to the FSD.

[0015] According to a second aspect, the invention provides an aircraft structure comprising a fuel stringer duct and a connector according to the first aspect of the invention. The fuel stringer duct comprises a wall, the wall being formed with a hole through the thickness of the wall, wherein a flange of the connector is positioned within the hole and a first sealing member forms a seal between an outer surface of the flange and an inner surface of the hole, the first sealing member being positioned between opposite outer surfaces of the wall. Thus, the first sealing member is located at a position through the thickness of the wall of the fuel stringer duct. One of the outer surfaces of the wall may be an outer surface of the fuel stringer duct. One of the outer surfaces of the wall may be an inner surface of the fuel stringer duct.

[0016] The inner surface of the hole may define the hole by forming the inner wall of the hole. It will be understood that the inner surface of the hole will be positioned between the opposing outer surfaces of the wall. The inner surface of the hole may be in a plane perpendicular to the plane defined by the first face of the connector. The inner surface of the hole may be in a plane perpendicular to the plane defined by the surface of the wall in which the hole is formed.

[0017] The first sealing member may be located between an outer surface and an inner surface of the wall. The inner surface may form an inner surface of the FSD. The wall of the FSD may be formed of a composite material, such as CFRP. The wall may have a thickness between 5 mm and 10 mm. For example, the wall may have a thickness of approximately 8 mm.

[0018] The inner surface of the hole can be formed by an additional sealing member. The first sealing member can be in direct contact with the additional sealing member to form a seal between the outer surface of the flange and the inner surface of the hole. The hole can be machined in the post-curing of the FSD, or the hole can be molded in the FSD. The additional sealing member can be a bushing set in the hole. The bushing can be "wet fit" in the hole, which means that a sealant can be provided between the bushing and the wall defining the hole in the FSD. The additional sealing member can be formed of PEEK or any other suitable material.

[0019] The connector may include a bridging member bridging onto the FSD on each side of the FSD, wherein the foot of the bridging member is fixed to a surface of the aircraft structure on the side of the FSD. The foot may be fastened to the surface using fasteners. Alternatively, the connector may be fastened to a wall of the FSD.

[0020] The FSD can be mounted on a panel. For example, the panel can be a wing skin. The FSD can be co-cured with the panel.

[0021] Of course, it will be appreciated that features described in relation to the connector of the first aspect of the invention may be incorporated into the aircraft structure of the second aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0023] Figure 1 A connector according to a first embodiment of the present invention is shown;

[0024] Figure 2 Shown in place on FSD Figure 1 Connectors;

[0025] Figure 3 It is in place on FSD Figure 1 A cross-sectional view of a connector;

[0026] Figure 4 yes Figure 3 Detailed view of the area within the box marked with an X in ;

[0027] Figure 5 is an exploded view showing an FSD, a connector, and a bushing for positioning between the FSD and the connector;

[0028] Figure 6 shows a connector according to a second embodiment of the present invention; and

[0029] Figure 7 It is in place on FSD Figure 6 A cross-sectional view of a connector. DETAILED DESCRIPTION

[0030] Figure 1 The connector 1 according to the first embodiment of the present invention is shown separately in FIG. Figure 2 FSD of the hat section of a composite aircraft structure in 5. Figure 2 In the embodiment of the present invention, the FSD is shown as being fixed to the wing skin 60. However, in other embodiments of the present invention, the FSD may be fixed to another part of the wing. The connector 1 includes a body 7 or crown having a first opening 9 located on a first face 11 of the body 7, a second opening 13 located on a second face 15, and an internal passage 17 extending through the crown, such as Figure 3 As shown in , a fluid can flow through the connector 1 between the FSD 5 and the fluid flow conduit. A flange 19 extends from the first face 11 and defines a first opening 9 on the first face 11. An outer surface 191 of the flange 19 is provided with an o-ring 20 around the periphery of the flange 19.

[0031] The connector 1 includes a bridging member 21 located on the opposite side of the first opening 9, and the bridging member 21 extends from the body 7. Figure 2As can be best seen in FIG. 1 , the bridging members 21 extend away from the first face 11 and are configured to bridge over the FSD 5 on each side of the FSD 5 to retain the body 7 of the connector 1 above the upper surface 51 of the wall forming the crown 55 of the FSD 5. Each of the bridging members 21 includes a foot 23 formed with a hole for securing the connector to the surface 25 on each side of the FSD and a web 27 located between the foot 23 and the body 7.

[0032] Reference Figure 3 and Figure 4 , the flange 19 extending from the first face 11 is configured to be inserted into a hole 53 formed in the wall forming the crown 55 of the FSD 5. The hole 53 may be molded into the FSD 5 during the curing process, or alternatively, the hole 53 may be machined in the post-curing of the FSD. Figure 4 As best seen in FIG. 1 , the o-ring 20 is retained in a groove 232 formed in the outer surface 191 of the flange 19, with the groove 232 and the o-ring 20 spaced apart from the first face 11 of the body 7 at a location approximately halfway along the height of the flange 19 (the height direction of the flange 19 being vertical in the orientation of the connector 1, as shown). In this case, the bore 53 is lined with a bushing 28, which may be Figure 5 53 is best seen in the drawing, such that the inner surface of the bore 53 is effectively formed by the bushing 28. In the presently described embodiment of the invention, the bushing 28 is formed of PEEK due to its advantageous structural properties and corrosion resistance. However, other suitable materials may certainly be used for the bushing. Figure 4 As can be best seen in FIG. 5 , with flange 19 positioned in bore 53 of FSD 5 , o-ring 20 is in direct contact with bushing 28 such that o-ring 20 forms a seal between outer surface 191 of the flange and inner surface 531 of bore 53 in FSD 5 .

[0033] The inherent material variability of carbon fiber reinforced plastic (CFRP) FSD 5 may result in Figure 3 The height H of the FSD 5 indicated in FIG. varies between the FSDs. Figure 3 The height D of the connector 1 indicated in FIG. 1 will typically have a much lower manufacturing tolerance due to the fact that the connector is machined from aluminum. In other embodiments, the connector may of course be formed from a different suitable material, such as corrosion resistant steel (CRES). Therefore, the distance DH between the upper surface 51 of the FSD 5 and the first face 11 of the connector 1 may be different for different FSDs, which makes it difficult to provide a reliable seal for the connector 1 between the upper surface 51 of the FSD 5 and the first face 11 of the connector 1 without requiring some additional machining of the FSD 5 (e.g., by using a sacrificial material that is machined down to size).

[0034] The connector 1 is configured such that when connected to the FSD 5, a seal is formed between the flange 19 of the connector 1 and the inner surface 531 of the hole 53, which is in a plane perpendicular to the upper surface 51 of the FSD 5 (i.e., the location where the seal is provided is within the hole 53, at a location between the upper surface 51 of the FSD 5 and the inner surface 52 of the opposite lower portion of the FSD 5). The seal is provided by an o-ring 20 that forms a sealing member around the flange 19 at a location spaced from the first face 11 of the body 7. This arrangement is particularly advantageous in embodiments of the present invention, such as the connector 1 described above, in which the connector 1 includes a bridging member 21 that is configured to secure the connector 1 to the surface 25 on each side of the FSD 5, because the connector 1 is insensitive to variations in the height H of the FSD 5 that are within the manufacturing tolerance of the FSD. For example, the height H of the FSD 5 may have a manufacturing tolerance of ±1 mm. As long as flange 19 can be positioned within bore 53 such that o-ring 20 can form a seal with inner surface 531 of bore 53, connector 1 can form a fluid tight seal with the FSD.

[0035] In an embodiment of the present invention, the flange 19 can be configured to position the o-ring 20 at a depth equal to about half of the expected thickness T of the wall 55 of the FSD. In the presently described embodiment, the FSD has a curing target thickness T equal to about 8 mm. Therefore, the connector 1 can be sized to position the o-ring 20 at a depth of 4 mm in the FSD having a height H equal to the precise target height, midway between the upper surface 51 of the FSD 5 and the opposing inner surface 52 of the FSD in the FSD. Positioning the o-ring 20 midway along the depth of the hole ensures equal positive and negative tolerances, in this case ±4 mm, which is much greater than the tolerance of the height of the FSD 5.

[0036] The present invention is not limited to arrangements bridged across a FSD, such as connector 1 described above. Figure 6 and Figure 7 1 shows a connector 101 according to a second embodiment of the present invention. The connector 101 includes a body 107 having a first opening 109 located on a first face 111 of the body 107, a second opening 113 located on a second face 115, and an internal passage 117 extending through the crown so that fluid can flow through the connector 1. It should be noted that the connector 101 of the second embodiment of the present invention is an "elbow" connector, wherein the first opening 109 at the first face 111 is located in a plane oriented at approximately 90 degrees to the second opening 113 on the second face 115.

[0037] Similar to the connector 1 of the first embodiment, a flange 119 extends from the first face 111 of the body 107 and defines a first opening 109 located on the first face 111, and the outer surface of the flange 119 is provided with an o-ring 120 around the periphery of the flange 119. The flange 119 is configured to be inserted into the hole 53 formed in the upper surface 51 of the FSD 5 so that the o-ring 120 forms a seal between the outer surface 1191 of the flange and the inner surface of the hole 53 in the wall 55 of the FSD 5. In this case, the connector 101 does not include a bridging member, but is provided with a hole 150 so that the first face 111 of the body 107 can be placed in abutment with the upper surface 51 of the FSD 5 and directly fastened to the FSD 5 using fasteners. Although the hole 150 passes through the body 107 in the presently described embodiment of the invention, it will be understood that other embodiments of the invention may be provided with the hole elsewhere; for example, in a coplanar flange extending from the side of the body 107.

[0038] While the present invention has been described and illustrated with reference to specific embodiments, those skilled in the art will appreciate that the invention lends itself to many different variations not specifically illustrated herein.

[0039] Where reference is made in the foregoing description to wholes or elements that have known, obvious or foreseeable equivalents, such equivalents are incorporated herein as if set forth individually. Reference should be made to the claims to determine the true scope of the invention, which should be interpreted as including any such equivalents. The reader will also understand that wholes or features of the invention described as preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims. Furthermore, it should be understood that such optional wholes or features, while potentially beneficial in some embodiments of the invention, may not be desirable in other embodiments and therefore may not be present in other embodiments.

[0040] Unless the context requires otherwise, the term "or" should be construed as "and / or".

Claims

1. A connector for connecting a fluid flow pipe to a fuel stringer pipe, the connector comprising a body, the body comprising: a first opening, the first opening being located on the first surface; a second opening, the second opening being located on a second face, the second face being configured to be connected to the fluid flow conduit; an internal passage, the internal passage being used for fluid passage between the first opening and the second opening; and a flange surrounding the first opening on the first face, the flange being configured to be inserted into a hole formed in a wall of the fuel stringer pipe, wherein an outer surface of the flange is provided with a first sealing member surrounding the flange, the first sealing member being configured to form a seal between the outer surface of the flange and an inner surface of the hole formed in the wall of the fuel stringer pipe.

2. The connector according to claim 1, wherein: The first sealing member is spaced apart from the first face of the body.

3. The connector according to claim 2, wherein: The first sealing member is spaced apart from the first face of the body by approximately 2 mm to 6 mm.

4. The connector according to claim 3, wherein: The first sealing member is an o-ring.

5. The connector according to claim 4, wherein: The outer surface of the flange is formed with a groove extending around the periphery of the flange, and the o-ring is located in the groove.

6. The connector according to any one of claims 1 to 5, wherein: The connector includes a bridging member located on an opposite side of the first opening, the bridging member extending from the body, the bridging member configured to bridge over the fuel stringer pipe on each side of the fuel stringer pipe, wherein the bridging member includes feet for securing the connector to a surface on each side of the fuel stringer pipe.

7. The connector according to any one of claims 1 to 6, wherein: The connector is provided with holes for fastening the connector to the fuel stringer pipe.

8. An aircraft structure comprising a fuel stringer duct and a connector according to any one of claims 1 to 7, the fuel stringer duct comprising a wall formed with holes through the thickness of the wall, wherein The flange of the connector is positioned within the bore and the first sealing member forms a seal between the outer surface of the flange and the inner surface of the bore, the first sealing member being positioned between opposing surfaces of the wall.

9. The aircraft structure according to claim 8, wherein: The inner surface of the hole is formed by an additional sealing member, and the first sealing member is in direct contact with the additional sealing member to form a seal between the outer surface of the flange and the inner surface of the hole.

10. An aircraft structure according to claim 8 or claim 9, wherein: The connector is a connector according to claim 6, and wherein the bridging member bridges over the fuel stringer pipe on each side of the fuel stringer pipe, and each of the feet is fixed to a surface of the aircraft structure on the side of the fuel stringer pipe.

11. An aircraft structure according to claim 8 or claim 9, wherein: The connector is a connector according to claim 7 and wherein the connector is fastened to a wall of the fuel stringer conduit.

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