Connection apparatus for improving the crashworthiness of aircraft fluid systems

A fluid connection system for fluidly connecting a pair of fluid reservoirs, such as fuel cells, includes a bellowed portion surrounding a connection portion through which fluid can flow between the two reservoirs. The bellowed portion allows for relative movement between the two reservoirs without breaking the fluid-tight connection between the two reservoirs. Also, a guard member surrounds at least some of the outer periphery of the bellowed portion. The guard member serves as a shield around the fluid-tight connection and bellowed portion, and thereby helps prevent damage to the fluid-tight connection in the event of a crash or hard landing.

TECHNICAL FIELD

This disclosure generally relates to crash-resistant fluid systems, and more specifically relates to crashworthy connection systems for fluidly-connected enclosures, including crashworthy connection systems for fluidly-connected fuel cells.

DETAILED DESCRIPTION

Some aircraft fluids (e.g., fuel, hydraulic fluid or other aircraft fluid) are transferred between components and systems through fluid transmission lines. In example implementations described here, the fluid transfer is through aircraft fuel transmission lines. However, in alternative embodiments, the fluid transfer can be through fluid transmission lines used to transport fuel and/or other fluids in other systems in which fluid is transported, e.g., automotive systems (e.g. automobiles, ATVs, motorcycles, etc.), fixed-wing aircraft, submersible systems, marine systems (e.g. personal watercraft, boats, etc.), agricultural systems (e.g. tractors, etc.), power equipment (e.g. generators, lawn mowers, pressure sprayers, etc.), systems that include gasoline engines, or other systems.

FIG. 1shows a schematic diagram of an example tiltrotor aircraft101. Aircraft101includes a fuselage103with attached wings105. Nacelles107are carried at the outboard ends of wings105and are rotatable between the helicopter-mode position shown and a forward-facing airplane-mode position (not shown). Nacelles107carry engines and transmissions109for powering rotor systems111in rotation. An engine may be an internal combustion engine, an electrical power source and associated motor, or any other suitable means for powering rotor system111. Each rotor system111is illustrated as having three blades113. Spinning covers115and nacelles107substantially enclose transmission109, obscuring transmission109from view inFIG. 1. The tiltrotor aircraft101can include a fuel storage system300. The fuel storage system300can be located within the fuselage103.

FIG. 2shows a schematic diagram of an example rotorcraft201. Rotorcraft201has a rotor system203with multiple rotor blades205. The pitch of each rotor blade205can be manipulated in order to selectively control direction, thrust, and lift of rotorcraft201. Rotorcraft201can further include a fuselage207, anti-torque system209, and an empennage211. The rotorcraft201can also include a fuel storage system300. The fuel storage system300can be implemented in one or more fluid storage tanks, e.g., fuel cells, of the tiltrotor aircraft101or the rotorcraft201(or both), as described below.

FIG. 3shows a schematic diagram of an example fuel storage system300. The fuel storage system300is typical of many different fuel systems that include multiple fuel cells that are fluidly connected to each other. The fuel storage system300includes a forward port fuel cell302, a forward starboard fuel cell304, a center fuel cell306, an aft fuel cell308, and an expansion tank310. The fuel storage system300can also include additional components, such as a fuel supply line312and a vent line314. The fuel cells302,304,306,308, and expansion tank310can include fuel storage bladders formed of a strong material that is suitable for storing fuel without allowing the fuel to seep therethrough. For example, Kevlar materials are known that can be suitably used to form the walls of a fuel bladder. Alternatively, fuel cells302,304,306,308, and expansion tank310can lack a separate fuel storage bladder and instead be provided with a fuel resistant coating on interior surfaces thereof such that the fuel cells302,304,306,308, and expansion tank310can store fuel without a bladder.

FIG. 4shows another schematic diagram of the fuel storage system300shown inFIG. 3, along with portions of an airframe. As shown inFIG. 4, the airframe includes several bulkheads, including bulkhead318. Some of the bulkheads may interpose two or more fluidly-connected fuel cells. For example, bulkhead318interposes fuel cells302and306. A hole344can be provided in the bulkhead318to serve as a passage for a fluid connection between the fuel cells302and306. However, in the event of a crash or hard landing, there may be relative motion between the bulkhead318and the fluid connection between the fuel cells302and306. This relative motion can cause the bulkhead318to puncture or sever the fluid connection between the fuel cells302and306, which can result in a loss of fuel and a fire hazard. It is therefore desirable to provide a fluid connection between the various fuel cells that is resistant to damage from other parts of an aircraft, including the airframe and bulkheads, in the event of a hard landing or a crash.

FIG. 5shows a cross-sectional view of a first embodiment of a fluid connection system320according to the present disclosure. The fluid connection system320is shown connecting fuel cells302and306through bulkhead318. The fluid connection system320includes a bellowed portion322that is integral to the bladder324of the fuel cell306. The bellowed portion322includes at least one crest portion326that extends outwardly from the fuel cell306, adjoining at least one root portion328that extends inwardly into the fuel cell306, in turn adjoining a connection portion330. Alternative embodiments can include additional crest portions326and root portions328, alternating in series with each other. In this embodiment, the bellowed portion322comprises an outer pleat325and an inner pleat329. An intermediate portion327forms a portion of each of the outer pleat325and the inner pleat329.

The connection portion330is attached to a fitting332such that a fluid-tight fluid path is formed between the fuel cells302and306. In the illustrated embodiment, the fitting332includes a cylindrical portion thereof that is attached to the connection portion330; however, in alternative embodiments, the cylindrical portion of the fitting332can alternatively have other non-cylindrical shapes, such as any of a variety of multi-faceted shapes that have polygonal cross-sections. The connection portion330can be connected to the fitting332a variety of ways, such as with the use of adhesives and/or hardware, for example a hose clamp or the like.

The fitting332is connected to the bladder334of the fuel cell302. The fitting332can be integral to the bladder334or can be attached to the bladder334using adhesives and/or connection hardware.

In the event of a crash or hard landing, the fuel cells302and306may be subject to forces that cause them to move relative to each other. The bellowed portion322allows for such relative motion without breaking the fluid-tight fluid connection between the two fuel cells302and306. For example, the bellowed portion322allows the fuel cells302and306to move towards and away from each other, and to move laterally (in and out of the drawing) and elevationally (up and down in the drawing) relative to each other, as well as combinations of those directions of relative movement, while still maintaining a fluid-tight fluid connection between the fuel cells302and306.

The connection system320further includes a guard member340. The guard member340can be generally cylindrical in shape as shown or can have other shapes, such as any of a variety of multi-faceted shapes that have polygonal cross-sections. The guard member340can optionally include a flanged portion342. The guard member340surrounds at least a portion of the bellowed portion322and at least a portion of the fitting332. More specifically, the guard member340surrounds at least a portion of the crest portion326and connection portion330of the bladder324, as well as a portion of the fitting332. Significantly, the guard member340extends through the hole344in the bulkhead318, and thereby interposes the bulkhead318and the fluid connection between the fuel cells302and306.

In the event of a crash or hard landing, the fuel cells302and306may be subject to forces that cause them to move relative to each other and relative to the bulkhead318. As a result, without the guard member340, the various components that form the fluid connection between the fuel cells302and306(i.e., the bellowed portion322and the fitting332) could be punctured, severed, or otherwise damaged by the bulkhead318or other debris. Therefore, the guard member340is provided in order to help prevent the bulkhead318from damaging the bellowed portion322and/or the fitting332in the event of a crash or hard landing. Preferably the guard member340is therefore formed of a material that is highly resistant to compressive and shearing forces, such as metal, composite, or acrylic material.

FIG. 6shows a cross-sectional view of a second embodiment of a fluid connection system420according to the present disclosure. The second embodiment of the fluid connection system420is substantially the same as the first embodiment320shown inFIG. 5, except that the second embodiment of the fluid connection system420includes a guard member440in place of the guard member340shown inFIG. 5. The guard member440includes one or a pair of flange members444for attaching the guard member440to the bulkhead318. The flange members444can be attached to the bulkhead318using adhesives and/or connection hardware, such as screws or nuts and bolts. WhileFIG. 6shows flange members444on both sides of the bulkhead318, alternative embodiments can include a flange member444on only one side of the bulkhead318. In the second embodiment, since the guard member440is fixed to the bulkhead318, the guard member440is more likely to stay fixed relative to the bulkhead318as compared to the first embodiment of the connection system320where the guard member340had more freedom to move laterally between the fuel cells302and306.

FIG. 7shows a cross-sectional view of a third embodiment of a fluid connection system520according to the present disclosure. The third embodiment of the fluid connection system520is substantially the same as the first embodiment320shown inFIG. 5, except that the third embodiment of the fluid connection system520includes a guard member540in place of the guard member340shown inFIG. 5. The guard member540of the third embodiment is connected to one or both of the fuel bladders324and334. In the illustrated embodiment, the guard member540is integrally formed with the fuel bladder324. Alternatively, the guard member540can be attached to the fuel bladder324, for example using adhesives, composite materials, and/or connection hardware, such as a hose clamp. The guard member540can alternatively be integral or attached to the fuel bladder334. In the third embodiment, since the guard member540is fixed relative to one or both of the fuel bladders324and/or334, the guard member540is more likely to stay fixed between the fuel cells302and306, and therefore remain fixed relative to the bellowed portion322and fitting332. This helps prevent the guard member540from being repositioned away from the components sought to be protected from the bulkhead318in the event of a crash or hard landing.