Patent Description:
A commonly used type of crew mask includes an inflatable head harness with inflatable elastic tubes that are inflated prior to placement of the harness over the head of the user, and that are then deflated to grip the user's head. A valve is connected to the tubes to control inflation by pressurized gas, such as from an oxygen supply of a regulator on the respiratory mask, and deflation.

Another similar type of oxygen supply system includes an oxygen supply with a face mask and an inflatable head harness. A plurality of chemical oxygen generators provide oxygen to a reservoir, to initially inflate the pneumatic head harness and provide an initial breathing supply during the startup of the chemical oxygen generators.

The prior art uses a harness, with an inflatable silicone inner tube, along with a regulator to provide oxygen for pilots. The inflation feature of the harness allows pilots to don the crew mask in a quick manner.

Examples of inflatable harnesses are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

In a typical conventional crew mask, illustrated in <FIG>, an inflatable crew mask assembly includes an inflatable harness <NUM> connected to an oronasal face seal molding or mask portion <NUM> formed to fit to a face of a wearer when the inflatable harness is fitted over the wearer's head and properly inflated. A lower forward portion of the mask portion includes a smoke goggle purge flow actuation lever <NUM>, a harness inflation control button <NUM>, a connector <NUM> between the inflatable harness and an oxygen supply regulator assembly <NUM>, and a control knob <NUM>. The regulator typically supplies breathing oxygen to the mask wearer through ports internal to the lower forward portion of the face seal, and also supplies oxygen or other breathing gas mixtures to the inflatable harness via an oxygen pressure supply hose <NUM>, including a pressure indicator <NUM>, coupling <NUM>, and microphone connection cable <NUM>. The inflatable harness typically includes a rear inflatable tube <NUM> or strap connected via connectors <NUM> to a lower inflatable tube <NUM> connected to the oxygen supply regulator assembly. The inflatable harness may also be adjustable for the size and comfort of the mask once inflated. Upon depression of the harness inflation button the oxygen from its source flows into the harness assembly.

The prior art relied on a silicone inner tube that inflated by pressurized oxygen and was constrained to not burst by a porous over-braid. Specifically, the prior art inflatable harness typically consists of an inflatable silicone tube treated with talc or talcum powder and covered with a braided sleeve of Nomex® braided material. The braiding helps the tube withstand higher pressures, and depending on the ratio of length of the Nomex® braided sleeve to tube length, the length of expansion can be controlled in the longitudinal direction while the diameter of the Nomex® braided sleeve controls tube expansion in the radial direction. The nominal operating pressure is <NUM> to <NUM> kPa (<NUM> to <NUM> psig).

As seen in <FIG>, there are several sections within the harness assembly with varying length of tubing and associated joints where these sections meet and are held in place with various means. The ends of the Nomex® covered silicone tubes are connected to the mask by means of crimped ferrules. Accessories, such as a back pad and head straps are attached to the Nomex® covered silicone tubes to create the harness shape. The ends of the braid are also taped during assembly of the harness to prevent the ends from unraveling.

During cycling of the harness assembly, the silicone tubes inflate as oxygen from the crew mask is supplied to the harness assembly, creating an increase in pressure. As noted above, the tubing increases in length in the longitudinal direction, while the radial increase in tube diameter is controlled by the Nomex® sleeve.

However, the silicone inner tube is highly susceptible to puncture and abrasion. One of the main observed failure modes of the prior art is leakage within the harness due to tears in the tube caused by stress and fatigue after repeated inflation cycles. Deformation of the tubing when a harness assembly is subjected to repeated inflation cycles causes the formation of small holes in the tubing that can consequently result in significant leakage from the tubing.

Moreover, the prior art fails to provide a robust assembly in controlling the radial diameter of the silicone tube by the Nomex® sleeve. Pleating of the Nomex® braid in manufacturing is both difficult and inconsistent. Once the harness assembly is inflated several times, the Nomex® braid pleats will form an irregular pattern along the length of the tube. This irregularity in pleat spacing creates a non-uniform radial increase in the tube diameter. This non-uniform radial increase in diameter creates areas in the tube length where the diameter will balloon. In these areas, the outer surface of the tube is eroded away, causing a decrease in tube wall thickness and eventual tube failure.

In addition, once a prior art harness has been cycled for approximately <NUM>,<NUM> cycles, the silicone tubing takes a set in the longitudinal direction. This set increases the length of the harness in the non-inflated condition, which has a detrimental effect on the harness tension and ultimately the ability of the crew mask to provide an adequate face seal.

It therefore would be desirable to provide an inflatable harness crew mask with an inflatable harness that is able to inflate and expand over a user's head without requiring the silicone tube to be treated with talc or talcum powder, the braid to be pleated, nor the ends of the braid to be taped during assembly of the harness. It would also be desirable to provide an inflatable harness crew mask with an inflatable harness having a braid material that is allowed to stretch in the longitudinal direction without an appreciable change in axial diameter. It would further be desirable to provide an inflatable harness crew mask with an inflatable harness having a braid whose diameter remains relatively constant over the stretched length such that the braid provides a consistent, controlled and limited expansion of the silicone tube in the radial direction. It also would be desirable to provide an inflatable harness crew mask whose number of harness cycles can be increased by <NUM> fold compared to the prior art, and can be inflatable from at least <NUM>,<NUM> times to up to <NUM>,<NUM> times without failure. It would be further desirable to provide an inflatable harness crew mask which has no appreciable change in harness tension measured before cycling compared to that measured after cycling. It would also be desirable to provide an inflatable harness crew mask which has significantly higher reliability than the prior art to withstand inflation related wear and tear over the lifetime of the crew mask without adding weight to the existing design. The present invention meets these and other needs.

The improved crew mask harness according to the present invention provides one or more benefits and advantages not previously offered by the prior art, including but not limited to, an aircraft inflatable harness assembly having significantly higher reliability to withstand inflation related wear and tear given the operational pressure range of <NUM> - <NUM> kPa (<NUM>-<NUM> psi) and over the lifetime of the crew mask without adding weight to the existing design.

Accordingly, the present invention provides for an aircraft inflatable harness assembly for an aircraft oxygen crew mask for providing regulated flow of oxygen on board an aircraft for an aircraft crew. The aircraft inflatable harness includes at least one inner inflatable tube having a normally deflated configuration and an inflated configuration. The inner inflatable tube has a first end and a second end, and is configured to be inflated to cause expansion of the harness assembly to allow the harness assembly to be placed over a user's head.

The inner inflatable tube includes a braided outer sleeve of polyethylene terephthalate elastic material. The outer sleeve of elastic material is configured to have a first length when the inner inflatable tube is in a normally deflated configuration, and the outer sleeve of elastic material is configured to longitudinally expand to a second length greater than the first length when the inner inflatable tube is in an inflated configuration. Inflation of the at least one inner inflatable tube causes the outer sleeve of elastic material to expand in a longitudinal direction to the second length, which allows the aircraft inflatable harness assembly to be placed over the user's head. Deflation of the inner inflatable tube causes the outer sleeve of elastic material to retract in a reverse longitudinal direction back to the first length, thus allowing the aircraft inflatable harness assembly to grip the user's head with a desired head tension.

According to a presently preferred aspect, the inner inflatable tube is a silicone tube. In another presently preferred aspect, the inner inflatable tube is a continuous inner inflatable tube. In another presently preferred aspect, the inner inflatable tube has an internal diameter of <NUM> to <NUM> (<NUM> inch to <NUM> inch). In another presently preferred aspect, the inner inflatable tube has a wall thickness of <NUM> to <NUM> (<NUM> inch to <NUM> inch).

In another presently preferred aspect, there is provided a plurality of inner inflatable tubes. In another presently preferred aspect, a mask attachment fitting having a barbed end is secured to the first end of the inner inflatable tube by a crimped ferrule. The mask attachment fitting is configured to connect to a crew mask for control of inflation and deflation of the inner inflatable tube. In another presently preferred aspect, a mask attachment tube is secured to the second end of said at least one inner inflatable tube by a crimped ferrule. In another presently preferred aspect, an elastic head strap is connected between the plurality of inner inflatable tubes for adjustment of positioning of the harness assembly on the user's head. In another presently preferred aspect, a back pad is connected between the plurality of inner inflatable tubes to form a contour of the harness assembly for positioning of the harness on the user's head.

In another presently preferred aspect, the outer sleeve of elastic material is heat-set. In another presently preferred aspect, the second length of the outer sleeve of elastic material in the inflated configuration is at most twice the first length of the outer sleeve of elastic material in the deflated configuration. In another presently preferred aspect, the second length of the outer sleeve of elastic material in the inflated configuration is up to twice the first length of the outer sleeve of elastic material in the deflated configuration.

In another presently preferred aspect, the inflatable harness assembly is dimensioned such that its performance is easily optimized by adjusting parameters related to oxygen pressure requirements. In another presently preferred aspect, the inflatable harness assembly is designed to withstand all flow requirements to ensure safe and reliable operation.

Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments in conjunction with the accompanying drawings, which illustrate, by way of example, the operation of the invention.

<FIG> describes a preferred embodiment of the aircraft inflatable harness assembly according to the present invention, in which there is provided an aircraft inflatable harness assembly <NUM> having inner inflatable tubes <NUM>, typically silicone and preferably continuous, each having a first end <NUM> and a second end <NUM>.

The inner inflatable tubes have an outer sleeve <NUM> of elastic material which is preferably made from heat-set, braided, polyethylene terephthalate (PT). Preferably, a braided sleeve available under the brand name CLEAN CUT FR (flame retardant), manufactured by TECHFLEX® with monofilament fibers, is used as the outer sleeve <NUM> of elastic material. The nature of the PT braided outer sleeve <NUM> allows it to stretch with the inner inflatable tube <NUM> in a longitudinal direction without an appreciable change in axial diameter, the diameter of the braid remaining relatively constant over the stretched length. This characteristic of the braid provides a consistent, controlled and limited expansion of the silicone tube in the radial direction. With the consistent control of the tube expansion in the radial direction, the tubing <NUM> is less prone to wear due to erosion of the tube surface resulting in a change to the tube wall thickness.

The aircraft inflatable harness assembly <NUM> further includes mask attachment fittings <NUM>, typically having a barbed end, which are inserted into the first end <NUM> of the inner inflatable tubes <NUM> and held in place with crimped ferrules <NUM>. A mask attachment tube <NUM> is inserted into the second end <NUM> of the inner inflatable tubes <NUM> and also held in place with crimped ferrules <NUM>. Elastic head straps <NUM> are connected to the inner inflatable tubes to adjust the positioning of the harness assembly on the user's head. A back pad <NUM> is connected to the inner inflatable tubes <NUM> to form a contour of the harness assembly for positioning of the harness on the user's head.

According to a preferred aspect, the length of the PT braided outer sleeve <NUM> is at least the length of the inner inflatable tube <NUM> between the transition zones of the harness created by the back pad <NUM> and the head straps <NUM>, with excess braid compressed along the length of the inner inflatable tube, thus promoting stretch of the braided outer sleeve <NUM> in the longitudinal direction during inflation. The ratio of sleeve length to tube length can be optimized and is dependent on the braid weave and the braid filament diameter of the braided outer sleeve <NUM>. Preferably, the inner inflatable tube and braided outer sleeve have a longitudinal stretch ratio of approximately <NUM>:<NUM> or less, that is, the length of the PT braid covered inner inflatable tube stretches up to approximately twice its original length. This ratio is set so that the harness can accommodate a wide variety of user head sizes and can vary based on the harness configuration. In a presently preferred aspect, the length of the PT braid covered inner inflatable tube stretches to at most twice its original length. Testing has shown that preferably having a longitudinal stretch ratio of approximately <NUM>:<NUM> or less allows the braided outer sleeve <NUM> to longitudinally expand in an inflated configuration without an appreciable change in axial diameter, thus providing consistent, controlled and limited expansion of the inner inflated tube in the radial direction.

The following tables illustrate various, non-limiting examples of tested configurations of longitudinal stretch ratios and sleeve-to-tube length ratios using a TECHFLEX® CLEAN CUT FR braided outer sleeve as the outer sleeve <NUM> of elastic materia (<NUM> inch = <NUM>):.

The inner inflatable tubes <NUM> and the PT braided outer sleeve <NUM> are normally in a deflated configuration. When oxygen or air pressure of <NUM> to <NUM> kPa (<NUM>-<NUM> psi) is supplied, inflation of the inner inflatable tube <NUM> causes the braided outer sleeve to stretch and expand in a longitudinal direction while remaining appreciably the same diameter in the radial direction, allowing the harness assembly to be placed over the user's head. When the harness assembly is deflated, deflation of the inner inflatable tube <NUM> causes the braided outer sleeve to retract in a reverse longitudinal direction back to its original length, allowing the harness assembly to grip the user's head with a desired head tension.

Claim 1:
An aircraft inflatable harness assembly for an aircraft oxygen crew mask operating between <NUM> to <NUM> kPa (<NUM> and <NUM> psi) for providing regulated flow of oxygen on board an aircraft for an aircraft crew, comprising:
at least two inner inflatable tubes (<NUM>) having a normally deflated configuration and an inflated configuration, said at least two inner inflatable tubes each having a first end (<NUM>) and a second end (<NUM>), said at least two inner inflatable tubes each tubes each being configured to be inflated to cause expansion of the harness assembly to allow the harness assembly to be placed over a user's head, said at least two inner inflatable tubes each including a braided outer sleeve (<NUM>) of polyethylene terephthalate elastic material, wherein each inner inflatable tube includes a silicone tube;
an elastic head strap (<NUM>) for adjustment of positioning of the harness assembly on the user's head;
a back pad (<NUM>) connected between the at least two inner inflatable tubes (<NUM>) to form a contour of the harness assembly for positioning of the harness on the user's head;
wherein said outer sleeve (<NUM>) of elastic material is configured to have a first length when the respective inner inflatable tube is in a normally deflated configuration, and wherein said outer sleeve (<NUM>) of elastic material is configured to longitudinally expand to a second length greater than the first length when the respective inner inflatable tube is in an inflated configuration, wherein a length of the outer sleeve (<NUM>) is at least a length of the respective inner inflatable tube (<NUM>) between transition zones of the harness created by the back pad (<NUM>) and the head strap (<NUM>), with excess braid compressed along the length of the respective inner inflatable tube (<NUM>);
wherein inflation of said at least two inner inflatable tubes (<NUM>) causes said outer sleeve (<NUM>) of elastic material to expand in a longitudinal direction to the second length to allow the aircraft inflatable harness assembly to be placed over the user's head, and
wherein deflation of said at least two inner inflatable tubes (<NUM>) causes said outer sleeve (<NUM>) of elastic material to retract in a reverse longitudinal direction back to the first length to allow the aircraft inflatable harness assembly to grip the user's head with a desired head tension.