SUSTAINABLE COMPOSITE CYLINDER

A composite cylinder assembly may comprise a tube liner and a port. The tube liner may include a closed bottom portion, a substantially cylindrical wall, and a domed head portion defining a neck. The port may comprise an outer diameter configured to fit into an inner diameter of the liner neck. The port may further comprise a lip including an outer diameter that is greater than the inner diameter of the liner neck. The port may also comprise a swage recess having an outer diameter that is less than the inner diameter of the liner neck. The port may be configured to press-fit into the liner neck. The lip may be configured to provide a surface area to weld the port to the liner neck. The swage recess may be configured to provide an area to swage the liner neck to the port.

FIELD

The present disclosure relates to composite cylinder assemblies, and more specifically, sustainable composite cylinder assemblies incorporated into aerospace applications.

BACKGROUND

Fiber wrapped reinforced metal lined high pressure composite gas cylinder assemblies incorporated into aerospace applications typically comprise seamless aluminum liners with relatively thick walls with significant variation in thickness. This renders the gas cylinder assemblies too large to be incorporated into space-constrained locations inside an aircraft such as passenger emergency breathing oxygen installed in the Passenger Service Unit (“PSU”) in overhead portions of an aircraft cabin. Even if gas cylinder assemblies were small enough to be incorporated into PSUs, the small package size would likely be at the cost of projectile impact resistance, which is required for gas cylinder assemblies installed in the aircraft passenger cabin within the engine rotor burst zone. For example, aluminum-lined composite cylinders are prone to fragmentation when pressurized with pure oxygen. Moreover, gas cylinder assemblies installed in PSUs and other space-constrained locations are typically fully metallic, making them heavier than composite cylinders, which tends to decrease fuel economy.

SUMMARY

A composite cylinder assembly is disclosed herein, in accordance with various embodiments. In various embodiments, the composite cylinder assembly may comprise a tube liner. The tube liner may comprise a closed bottom portion, a domed head portion, and a substantially cylindrical wall coupled to the closed bottom portion and the domed head portion. The substantially cylindrical wall may be between the closed bottom portion and the domed head portion. In various embodiments, the domed head portion may define a liner neck.

The composite cylinder assembly may further comprise a port. In various embodiments, the port may comprise an outer diameter configured to fit into an inner diameter of the liner neck. The port may further comprise a lip and a swage recess. The lip may comprise an outer diameter that is greater than the inner diameter of the liner neck. The swage recess may comprise an outer diameter that is less than the inner diameter of the liner neck.

In various embodiments, the port may be configured to press-fit into the liner neck. In various embodiments, the lip many be configured to provide a surface area to weld the port to the liner neck. In various embodiments, the swage recess may be configured to provide an area to swage the liner neck to the port.

In various embodiments, the tube liner may further comprise a spindle. The spindle may be a cylindrical disk. In various embodiments, the tube liner may comprise a carbon fiber overwrap. The carbon fiber overwrap may further comprise a glass fiber layer. In various embodiments, the tube liner may be made of metal. In various embodiments, the substantially cylindrical wall of the tube liner may be seamed. In various embodiments, the tube liner may be spin welded.

In various embodiments, the port may further define a channel. In various embodiments, the channel may be substantially cylindrical. In various embodiments, the liner neck may be stoppered at the port lip. In various embodiments, the liner neck may be spin welded to the lip. In various embodiments, the liner neck may be fusion welded to the lip.

A composite cylinder assembly is also disclosed herein. In various embodiments, the composite cylinder assembly may comprise a tube liner. The tube liner may comprise a closed bottom portion, a domed head portion, and a substantially cylindrical wall coupled to the closed bottom portion and the domed head portion. The substantially cylindrical wall may be between the closed bottom portion and the domed head portion. In various embodiments, the domed head portion may define a liner neck. In various embodiments, the closed bottom portion may be deep drawn. In various embodiments, the domed head portion defining the liner neck may be deep drawn.

The composite cylinder assembly may further comprise a port. In various embodiments, the port may comprise an outer diameter configured to fit into an inner diameter of the liner neck. The port may further comprise a lip and a swage recess. The lip may comprise an outer diameter that is greater than the inner diameter of the liner neck. The swage recess may comprise an outer diameter that is less than the inner diameter of the liner neck.

In various embodiments, the port may be configured to press-fit into the liner neck. In various embodiments, the lip many be configured to provide a surface area to weld the port to the liner neck. In various embodiments, the swage recess may be configured to provide an area to swage the liner neck to the port.

In various embodiments, the cylinder wall may be fusion welded to the domed head portion and to the closed bottom portion. The substantially cylindrical wall may comprise a fusion weld line along a girth of the substantially cylindrical wall. In various embodiments, the substantially cylindrical wall may be made of metal. The substantially cylindrical wall may comprise a seam weld line. In various embodiments, the substantially cylindrical wall may be fusion welded to the bottom portion at a first end of the substantially cylindrical wall. The substantially cylindrical wall may be fusion welded to the domed head portion at a second end of the substantially cylindrical wall. In various embodiments, the tube liner may comprise a plurality of fusion weld lines.

A method of manufacturing a composite cylinder assembly is also disclosed herein. In various embodiments, the method may comprise forming a tube liner. The tube liner may comprise a closed bottom portion, a domed head portion, and a substantially cylindrical wall coupled to the closed bottom portion and domed head portion. The substantially cylindrical wall may be between the closed bottom portion and the domed head portion. The domed head portion may define a liner neck.

The method may further comprise fabricating a port. The port may comprise an outer diameter configured to fit into an inner diameter of the liner neck. The port may comprise a lip and a swage recess. In various embodiments, the lip may comprise an outer diameter that is greater than the inner diameter of the liner neck. In various embodiments, the swage recess may comprise an outer diameter that is less than the inner diameter of the liner neck.

The method may further comprise press-fitting the port into the liner neck. In various embodiments, the method may further comprise welding the port to the liner neck at the lip of the port. In various embodiments, the method may further comprise swaging the liner neck to the port at the swage recess.

In various embodiments, the forming step of the method may further comprise spin welding the tube liner. In various embodiments, the forming step may comprise deep drawing the closed bottom portion and the domed head portion. The forming may further comprise fusion welding the domed head portion to the bottom portion to form the substantially cylindrical wall. The substantially cylindrical wall may comprise a fusion weld line along a girth of the substantially cylindrical wall.

In various embodiments, the forming may further comprise deep drawing the closed bottom portion and the domed head portion. The forming may further comprise fabricating the substantially cylindrical wall from sheet metal. In various embodiments, the forming may further comprise seam welding the substantially cylindrical wall. Forming may further comprise fusion welding the substantially cylindrical wall to the bottom portion at a first end of the substantially cylindrical wall. Forming may further comprise fusion welding the substantially cylindrical wall to the domed head portion at a second end of the substantially cylindrical wall.

DETAILED DESCRIPTION

A composite cylinder, as disclosed herein, may be used to provide oxygen to passengers and crew. The composite cylinder may also be used to inflate aircraft evacuation systems, such as evacuation slides and life-raft assemblies. This disclosure is not limited in that regard. The composite cylinder disclosed herein may be advantageous over conventional seamless aluminum-lined composite cylinders in that the composite cylinder has a greater service life over conventional seamless aluminum-lined composite cylinders, reducing costs. Moreover, decreasing the number of re-inspections and re-tests required decreases the likelihood of cylinder failure over the service life of an aircraft, PSU, or evacuation assembly, since the cylinders are more likely to be damaged during re-inspection and re-testing.

Composite cylinders approved to be installed and used in aircraft may be securely installed in locations in the aircraft where there is minimal or no threat of damage over its service life, which may be, for example, fifteen years. The service life of any cylinder, composite or otherwise, may be significantly less than the service life of the aircraft in which it is installed, which may be, for example, thirty years. Extending the service life of conventional seamless aluminum-lined composite cylinders to match that of the aircraft may be costly and time-consuming. Service life extension efforts increase carbon emissions due to removal, packaging, transport, and significant testing, which may require, for example, burst testing and drop testing.

Accordingly, removing a cylinder from an aircraft for re-inspection and re-testing poses a risk of damage to the cylinder several times over its service life. Re-inspection and re-testing involves removal of the cylinder from the aircraft, transporting the pressurized cylinder to the manufacturer, depleting the gas, removing the valve and/or regulator, visual inspection of the interior of the cylinder, filling with fluid, holding the cylinder to a test pressure (i.e, a minimum of1.5times the service pressure), depleting, cleaning and drying of the test fluid, reassembling the valve and/or regulator, refilling with gas, transporting back to the aircraft, and reinstalling the cylinder in the aircraft. In re-inspecting and re-testing evacuation assembly cylinders, the entire inflatable evacuation assembly is at risk of damage since the assembly must be deployed (i.e., inflated), inspected, and then repackaged before reinstallation in the aircraft. Repackaging an evacuation assembly may be complex, difficult, and time-consuming, as it may require a crew of highly-trained personnel up to a week to complete. The composite cylinder disclosed herein may comprise a service life in excess of fifteen years and may enable an increase in time between re-inspection and re-test periods or eliminate re-inspection and re-test periods entirely. The composite cylinder may be optimized to fit into space-constrained locations in an aircraft, such as a PSU or evacuation assembly.

Referring toFIG.1A, a cabin51of an aircraft50is shown, according to various embodiments. The aircraft50may be any aircraft such as an airplane, a helicopter, or any other aircraft. The aircraft50may include a passenger service unit (PSU)10corresponding to each row of seats62. The PSU may be, for example, an emergency breathing oxygen PSU. The cabin51may include overhead bins52, passenger seats54forming the row of passenger seats62for supporting passengers55, etc. In various embodiments, the PSU10may be integral with the overhead bins52or the PSU10may be separate from the overhead bins52. The present disclosure is not limited in this regard. In various embodiments, each PSU10may comprise a cylinder assembly300(FIG.3A). In various embodiments, the cylinder assembly300may be a composite cylinder assembly and oxygen delivery assembly. The cylinder assembly300is configured to transfer a fluid (e.g., oxygen gas) to each passenger. Accordingly, the cylinder assembly300may be, for example, a composite gas cylinder.

Referring toFIG.1B, the aircraft50is shown in accordance with various embodiments. The aircraft50may include a system of composite cylinder assemblies300(FIG.3A) located throughout the aircraft50and corresponding to the flight crew11, flight attendants12, and passengers55. In various embodiments, the cylinders300(FIG.3A) may be integral within a non-passenger-carrying area of the aircraft. The present disclosure in not limited in this regard. The cylinder300(FIG.3A) may transfer a fluid (e.g., oxygen gas) to each crew member, flight attendant, and/or passenger.

With reference toFIG.2, an evacuation assembly106is illustrated with the evacuation slide108of the evacuation assembly106in an inflated or “deployed” position. In accordance with various embodiments, evacuation assembly106includes an evacuation slide108. During deployment, evacuation slide108is inflated using pressurized gas from a compressed fluid source, such as, for example, a cylinder assembly300(FIG.3A). Evacuation slide108may include a head end110and a toe112opposite head end110. A sliding surface114of evacuation slide108extends from head end110to toe end112. In various embodiments, one or more inflation sensor(s)118is/are operably coupled to evacuation slide110. Inflation sensor(s)118may include pressure sensor(s) configured to measure a pressure of evacuation slide108. In various embodiments, the cylinder assembly300may comprise compressed carbon dioxide or nitrogen, or combination thereof. In various embodiments, the cylinder assembly300may inflate various evacuation assemblies, such as, for example, evacuation life rafts. Aircraft evacuation assemblies comprising the cylinder assembly300may be installed in aircraft exit door compartments, the wings, the fuselage, or stored within the aircraft.

Referring toFIG.3, a composite cylinder assembly300is shown in accordance with various embodiments. Specifically, a tube liner302of the composite cylinder assembly300is shown. The tube liner302may comprise a closed bottom portion304, a substantially cylindrical wall306, and a domed head portion308. In various embodiments, the domed head portion308may define a liner neck310. The tube liner302of the composite cylinder assembly300may be configured to be any size suitable for portability and/or stowage in the aircraft. For example, in various embodiments, the tube liner302may define a water volume of 0.25 liters to 0.5 liters (0.055 gallons (gal) to 0.11 gal), 0.5 liters to 0.75 liters (0.11 gal to 0.165 gal), 0.75 liters to 1 liter (0.165 gal to 0.22 gal), or 1 liter to 2 liters (0.22 gal to 0.44 gal), and the like. In various embodiments, the tube liner302may be greater than 2 liters (0.44 gal). For example, the tube liner302may be 2 liters to 15 liters (0.44 gal to 3.3 gal), 15 liters to 30 liters (3.3 gal to 6.6 gal), or 30 liters to 50 liters (6.6 gal to 11 gal).

The cylinder assembly300may comprise gaseous oxygen, which may replace chemically generated oxygen in the PSU, enabling an aircraft to fly for as much as 60 minutes longer to reach an altitude where emergency breathing oxygen is not required. While the composite cylinder assembly300shown inFIG.3is substantially cylindrical, it can be appreciated by those skilled in the art that the cylinder may be configured to any shape suitable for efficient stowage or placement in the PSU.

In various embodiments, the tube liner302may be made of steel, stainless steel, aluminum, aluminum alloys, brass, titanium, and the like. For cylinder assemblies housing oxygen and placed in the PSU, or in other engine rotor burst zone areas of the aircraft passenger cabin, it may be advantageous to utilize a stainless steel tube liner. Stainless steel liners may be less prone to fragmentation or bursting upon contact with a projectile. Moreover, a stainless-steel liner may have a minimum burst pressure at least three times a service pressure. Stated differently, a stainless-steel liner may have a minimum burst pressure at least three times the pressure it is filled to before installation in the aircraft. As will be discussed further below in reference toFIG.7, stainless steel liners may be fiber overwrapped cylinders (i.e., composite cylinders) pressurized with pure oxygen. Fiber overwrapped composite cylinders may be even less prone to fragmentation upon impact with a projectile.

In various embodiments, the tube liner302may be formed via metal spinning. For example, in various embodiments, the domed head portion308may be spun into an open neck shape. Accordingly, the domed head portion308may define a liner neck310. Furthermore, in forming the tube liner302via metal spinning, the substantially cylindrical wall306of the tube liner302may be seamed or seamless. In various embodiments, the tube liner302may be optionally exposed to an elevated temperature treatment to improve the mechanical properties of the liner302. In various embodiments, the tube liner302may comprise a spindle312. The spindle312may be coupled to the bottom portion304of the tube liner302. The spindle312may be a cylindrical disk configured to adhere to the spin-welded closed bottom portion304of the tube liner302. For example, the spindle312may be welded to the closed bottom portion304. In various embodiments, the spindle312may be incorporated into the closed bottom portion304via hydrospinning or deep drawing. In various embodiments, the spindle312may be configured to wind fiber onto the tube liner302. In various embodiments, the spindle312may be made of steel, stainless steel, aluminum, aluminum alloy, brass, titanium, and the like.

Referring toFIGS.4A,4B, and5, the cylinder assembly300may further comprise a port401. In various embodiments, the port401may comprise an outer diameter402configured to fit into an inner diameter311(FIG.3) of the liner neck310. The port401may further comprise a lip404and a swage recess406. The lip404may comprise an outer diameter that is greater than the inner diameter311of the liner neck310, which may enable depth control during swaging the liner neck310to the port401. The swage recess406may comprise an outer diameter that is less than the inner diameter311of the liner neck310. This may provide an area to swage the liner neck310to the port401. In various embodiments, the port401may define a channel408. In various embodiments, the channel408may be threaded on an inner surface. In various embodiments, the channel408may be substantially cylindrical. The channel408may be configured to allow one of a gas, liquid, or the like, to pass therethrough.

In various embodiments, as further shown inFIGS.5and6, the port401may be configured to press-fit into the liner neck310. Accordingly, the port outer diameter402may be similar to the liner neck inner diameter311to provide a pressed fit inside the liner neck310. The lip404of the port401may be configured to stop the liner neck310at the lip404. Accordingly, the lip404may control the depth of the press fit. In various embodiments, the lip404may be configured to provide a surface area to weld the port401to the liner neck310. In various embodiments, the liner neck310may be configured to be spin welded to the port lip404. In various embodiments, the liner neck310may be configured to be fusion welded to the port lip404. In various embodiments, the swage recess406may be configured to provide an area to swage the liner neck310to the port401. Accordingly, swaging the liner neck310to the port401helps retain the port401during burst testing. In various embodiments, the port401may be made of steel, stainless steel, aluminum, aluminum alloys, brass, titanium, and the like.

With reference toFIG.7, the composite cylinder assembly300is shown in accordance with various embodiments. As shown, the tube liner302of the composite cylinder assembly300comprises a carbon fiber overwrap715. It may be advantageous to overwrap a metallic liner with carbon fiber, since the carbon fiber may be the primary strength of the cylinder, increasing the average burst pressure. By way of example, a stainless-steel liner may have a burst pressure of about 9,500 psi (65.5 megapascal (MPa)) at a service pressure of 3,000 psi (20.68 MPa). With a carbon-fiber overwrap, the liner may reach a 20,000 psi (137.9 MPa) burst pressure.

An additional benefit of incorporating the described carbon fiber overwrap715is that the metallic liner may then act as a non-load-sharing, gas-impermeable bladder, holding the gas and preventing the gas from permeating and/or oxidizing the assembly. In this case, the majority of the strength comes from the carbon fiber overwrap715. Accordingly, the liner302may be a non-load-sharing liner. The strength of a carbon fiber overwrapped non-load-sharing liner may increase the service life of the composite cylinder assembly300in operation. Moreover, a carbon fiber overwrapped stainless-steel liner may be a lighter weight than an all-metal or load-sharing liner carbon fiber overwrapped configuration. For example, in an aircraft having 175 cylinders, one for each passenger, the weight savings from a carbon fiber overwrapped non-load-sharing liner may enable the addition of one extra passenger, or more cargo, on board. Accordingly, the non-load-sharing liner may benefit in the way of sustainability both in operating life and weight savings.

In various embodiments, the carbon fiber overwrap715may further comprise a glass fiber layer716. The glass fiber layer716may be configured to protect a label717. For example, the glass fiber layer716may be configured to protect an orange label indicating a composite cylinder assembly configured for an evacuation slide, or a green label indicating a composite cylinder assembly housing oxygen.

Referring toFIG.8, a composite cylinder assembly800is shown in accordance with various embodiments. In various embodiments, the composite cylinder assembly800may comprise a tube liner802. As shown, the tube liner802may comprise a closed bottom portion804, a substantially cylindrical wall806, and a domed head portion808. In various embodiments, the domed head portion808may define a liner neck810. The domed head portion808and closed bottom portion804may be hydroformed. In various embodiments, the domed head portion808and closed bottom portion804may be deep drawn stamped (i.e., deep drawn). In various embodiments, the domed head portion808and the closed bottom portion804may be trimmed to a desirable length.

In various embodiments, the domed head portion808and closed bottom portion804may be subjected to elevated temperature treatment and subsequent controlled cooling to improve the mechanical properties of the composite cylinder assembly800during and after forming.

In various embodiments, the substantially cylindrical wall806may be configured to be formed by fusion welding the domed head portion808to the bottom portion804. Accordingly, the substantially cylindrical wall806may comprise a fusion weld line813along a girth of the substantially cylindrical wall806, forming a shorter length composite cylinder assembly.

In various embodiments, and as shown inFIG.9, a substantially cylindrical wall906may be configured to be fabricated from sheet metal, for example, stainless steel. The substantially cylindrical wall906may be configured to be seam welded. Accordingly, the substantially cylindrical wall906may comprise a seam weld line914. In various embodiments, the substantially cylindrical wall906may be configured to be fusion welded to the bottom portion904at a first end916of the substantially cylindrical wall906. The substantially cylindrical wall906may also be configured to be fusion welded to the domed head portion908at a second end918of the substantially cylindrical wall906. Accordingly, the tube liner802may comprise a plurality of fusion weld lines913. This embodiment may be well-adapted for longer length cylinder assemblies. The cylinder assemblies shown inFIGS.8and9may comprise the port401shown inFIGS.4A and4B, andFIGS.5-7, and previously described herein.

FIG.10shows a method200of manufacturing a composite cylinder assembly300, in accordance with various embodiments. In various embodiments, the method200may comprise forming (step201) a tube liner302. The tube liner302may comprise a closed bottom portion304, a substantially cylindrical wall306, and a domed head portion308. The domed head portion may define a liner neck310.

The method200may further comprise fabricating (step202) a port401. The port401may comprise an outer diameter402configured to fit into an inner diameter311of the liner neck310. The port401may comprise a lip404and a swage recess406. In various embodiments, the lip404may comprise an outer diameter that is greater than the inner diameter311of the liner neck310. In various embodiments, the swage recess406may comprise an outer diameter that is less than the inner diameter311of the liner neck310.

The method200may further comprise press-fitting (step203) the port401into the liner neck310. In various embodiments, the method200may further comprise swaging (step204) the liner neck310to the port401at the swage recess406. In various embodiments, the method200may further comprise welding (step205) the port401to the liner neck310at the lip404of the port401. The welding (step205) may be, for example, fusion welding.

In various embodiments, the forming step (step201) of the method200may further comprise metal spinning (step206) the tube liner302into a domed head portion defining a neck. The forming step (step201) of the method200may further comprise metal spinning (step207) the tube liner302into a closed bottom portion. In various embodiments, the forming step (step201) may comprise hydroforming (steps208and209) the closed bottom portion804and the domed head portion808. In various embodiments, the tube liner's closed bottom portion804and domed head portion808may be formed via deep drawing. The present disclosure is not limited in this regard. The forming (step201) may further comprise fusion welding (step210) the domed head portion808to the bottom portion804to form the substantially cylindrical wall806. The substantially cylindrical wall806may comprise a fusion weld line813along a girth of the substantially cylindrical wall806.

In various embodiments, the forming (step201) may further comprise hydroforming (steps208and209) the closed bottom portion904and the domed head portion908. In various embodiments, the tube liner's closed bottom portion904and the domed head portion908may be formed via deep drawing. The present disclosure is not limited in this regard. The forming (step201) may further comprise fabricating (step211) the substantially cylindrical wall906from sheet metal such as stainless steel. In various embodiments, the forming (step201) may further comprise seam welding (step212) the substantially cylindrical wall906. The substantially cylindrical wall906may comprise a seam weld914. The forming (step201) may further comprise fusion welding (step213) the substantially cylindrical wall906to the bottom portion904at a first end916of the substantially cylindrical wall906. Forming (step201) may further comprise fusion welding (step214) the substantially cylindrical wall906to the domed head portion908at a second end918of the substantially cylindrical wall906.