Patent Description:
Exterior lighting on an aircraft enhances safety on the ground, during taxiing, and in-flight. Exterior systems often include anti-collision lighting, floor and spotlights, navigation lights and beacons, and emergency lights. These lights, which can be found on the upper and lower fuselage, tail, and wings, are subjected to intense environmental conditions, such as high winds and storms, as well as vast temperature and pressure changes during aircraft climb and descent. These conditions can damage the lighting systems. For example, since the external ambient air pressure varies with flight altitude, the light units are usually vented to avoid excessive overpressure or loss of pressure formed during flight ascent and descent periods. In exchanging air between the interior of an exterior light unit and the environment, water vapor in the air may flow into the exterior light unit and may eventually condense within the unit as the temperature changes. Liquid water build-up may deteriorate light unit functionality, threating operational safety of the entire aircraft. A light unit is disclosed in <CIT>. The light unit is provided with a drain valve comprising first and second housing portions with matching threads allowing them to be screwed together, a spring mounted to a protrusion of a bottom plate of the second housing portion and supporting a plunger, the plunger comprising a duct, a semi-permeable membrane and a sealing ring arranged along its circular outer periphery. <CIT>, <CIT>, <CIT>, <CIT> and <CIT> describe valves with magnets.

A valve is provided as defined by claim <NUM>.

In various embodiments, the poppet may further comprise a poppet stem. In various embodiments, the poppet stem may define a channel. In various embodiments, the channel may be configured to permit at least one of air and water vapor to pass therethrough. In various embodiments, the poppet may further comprise a membrane. The membrane may be a semi-permeable membrane. In various embodiments, the membrane may be configured to overlay the poppet stem defining the channel. In various embodiments, the membrane may be configured to permit at least one of air and water vapor to pass therethrough. In various embodiments, the membrane may be further configured to be impermeable to liquid water.

In various embodiments, the magnet may comprise a plurality of annular segments. The plurality of annular segments may define a plurality of recesses. Each recess may extend between the inner cylindrical face and the outer cylindrical face of the magnet. In various embodiments, the magnet may be a continuous, annular magnet.

An aircraft light unit is also provided as defined by claim <NUM>.

In various embodiments, the poppet may further comprise a poppet stem. In various embodiments, the poppet stem may define a channel. In various embodiments, the channel may be configured to permit at least one of air and water vapor to pass therethrough.

In various embodiments, polymer seal may be an O-ring. In various embodiments, the polymer seal may be configured to retain the poppet to the shoulder portion in a seated position.

In various embodiments, the semi-permeable membrane may be configured to overlay the poppet stem defining the channel. In various embodiments, the semi-permeable membrane may be configured to permit at least one of air and water vapor to pass into the channel. In various embodiments, the semi-permeable membrane may be further configured to be impermeable to liquid water. In various embodiments, the liquid water may be configured to accumulate along the membrane.

In various embodiments, the magnetic flux traversing across the air gap may develop a magnetic force across the air gap. In various embodiments, the magnetic force across the air gap may be configured to attract the poppet to the inner surface of the shoulder portion. In various embodiments, the magnetic force may be configured to close the valve. In various embodiments, the poppet may be configured to move out of the seated position and open the valve when the magnetic force across the air gap is exceeded by a pressure force of the impermeable liquid water acting on the poppet. In various embodiments, the magnetic force across the air gap may decrease as the valve opens.

In various embodiments, the inner body may define a plurality of cavities. In various embodiments, the plurality of cavities may be configured to permit water to drain out of the valve as the valve opens. In various embodiments, the pressure force of the impermeable liquid water accumulated along the semi-permeable membrane may decrease as the water drains out the valve. In various embodiments, the magnetic force across the air gap may be configured to increase as the pressure force of the liquid water within the valve decreases. In various embodiments, the increasing magnetic force across the air gap may shift the poppet back into a seated position.

A method of assembling a valve for an aircraft light unit is also provided as defined by claim.

Further embodiments are provided as defined in the respective dependent claims.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized within the scope of the invention as defined by the claims. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option.

With reference to <FIG>, an aircraft <NUM> in accordance with various embodiments may comprise aircraft systems, for example, one or more landing gear such as landing gear <NUM>, which may generally support aircraft <NUM> when aircraft is not flying, allowing aircraft <NUM> to taxi, take off, and land without damage. Aircraft <NUM> may include one or more exterior lamps <NUM>, or lighting units, such as, for example, landing lights <NUM>, taxi lights <NUM>, and navigation lights <NUM>. Referring to <FIG> and <FIG>, the aircraft <NUM> is illustrated according to various embodiments. The aircraft <NUM> includes a fuselage <NUM>, a pair of wings <NUM>, and a pair of engines <NUM> for each wing <NUM>. The aircraft <NUM> include landing lights <NUM>, taxi lights <NUM>, and runway turnoff lights <NUM>. These lights <NUM>, <NUM>, and <NUM> may be of any appropriate configuration and disposed at any appropriate location or combination of locations on the exterior of the aircraft <NUM>. Aircraft <NUM> may include any number of other exterior lamps <NUM> such as logo lights, engine scan lights, anti-collision lights, strobe lights, beacon lights, cargo compartment lights, obstruction lights, landing gear lights, and/or the like.

Due to the effects of the ambient environment on the exterior lamps <NUM>, the exterior lamps <NUM> may comprise a variety of pressure release mechanisms, for example, one or more pressure release valves. As fluid in the exterior lamp is collected in the ambient air, the valves may release the fluid to prevent damage to the exterior lamp.

<FIG> illustrate cross-sections of a magnetically controlled fluid drain valve <NUM>. As shown, the valve <NUM> includes an inlet fitting body <NUM>, an inner body <NUM>, an outer body <NUM>, and a permanent magnet <NUM>. The inlet fitting body <NUM> includes a collar portion <NUM> and a shoulder portion <NUM>. The collar portion <NUM> at least partially defines a lighting cavity <NUM>. In various embodiments, the collar portion <NUM> may be configured to assemble at the lighting cavity <NUM> to a corresponding structure of the lighting housing. In various embodiments, and as shown by the y-y' axis in <FIG>, gravity may be in the negative y direction along the y-y axis. In various embodiments, liquid water, water vapor, and air, may flow from the lighting housing through the collar portion <NUM> in the negative y direction. The collar portion <NUM> and the shoulder portion <NUM> are comprised of different materials. The collar portion <NUM> is comprised of a non-magnetic material, and the shoulder portion <NUM> comprises a magnetic material. The shoulder portion <NUM> comprises an inner surface at least partially defining an air gap <NUM>.

With further reference to <FIG> and <FIG>, the inner body <NUM> includes a poppet <NUM>. As shown, the poppet <NUM> is disposed between the inner surface of the shoulder portion <NUM> and a seat <NUM>. The seat <NUM> is configured to support the poppet <NUM>. In various embodiments, the seat <NUM> may be a spring. The poppet <NUM> has an annular groove configured to retain a polymer seal <NUM>. The polymer seal <NUM> may be configured to couple the poppet <NUM> to the inner surface of the shoulder portion <NUM> of the inlet fitting body <NUM>. In various embodiments, the inner surface of the shoulder portion <NUM> may be serrated to improve coupling of the polymer seal <NUM> to the inner surface of the shoulder portion <NUM>. In various embodiments, the polymer seal <NUM> may be configured to retain the poppet <NUM> to the shoulder portion <NUM> in a seated position. In various embodiments, the polymer seal <NUM> may be an O-ring, or any substantially ring-like shape. As shown in <FIG>, the valve <NUM> may be in a closed position, and the poppet <NUM> in a seated position, when the polymer seal <NUM> is coupled to the inner surface of the shoulder portion <NUM>. In various embodiments, the polymer seal <NUM> coupled to the inner surface of the shoulder portion <NUM> may prevent the ingress of fluid into the valve's <NUM> inner body <NUM>.

Referring to <FIG> and <FIG>, the poppet <NUM> may further comprise a poppet stem defining a channel <NUM>. In various embodiments, the channel <NUM> may be configured to permit at least one of air and water vapor to pass therethrough. In doing so, the poppet <NUM> may be configured to control the flow of gas exchanged between the lighting unit and the external environment. In various embodiments, the poppet <NUM> may include a membrane <NUM>. In various embodiments, the membrane <NUM> may be configured to overlay the poppet stem defining the channel <NUM>. In various embodiments, the membrane <NUM> may be disposed within a diameter of the polymer seal <NUM>.

In various embodiments, the membrane <NUM> may be semi-permeable and may be configured to permit air, water vapor, and other gases, to pass therethrough, exchanging gases with the external environment via the channel. It may be especially advantageous to allow water vapor to be exchanged to prevent its condensation into liquid water within the valve <NUM> and/or lighting housing. Some water vapor may condense and accumulate as liquid water along the semi-permeable membrane <NUM>. In various embodiments, the membrane <NUM> may be impermeable to liquid water. In various embodiments, the membrane <NUM> may comprise expanded polytetrafluoroethylene.

In further reference to <FIG>, a magnetically controlled fluid drain valve comprises a permanent magnet <NUM>. The magnet <NUM> is disposed between the inner body <NUM> and the outer body <NUM>. In various embodiments, and with further reference to <FIG>, the magnet <NUM> may further comprise a plurality of annular segments <NUM>. The plurality of annular segments <NUM> may define a plurality of recesses <NUM>. The magnet <NUM> further comprises an inner cylindrical face <NUM> having a north pole and an outer cylindrical face <NUM> having a south pole. In various embodiments, the magnet may be radially polarized between the inner cylindrical face <NUM> and the outer cylindrical face <NUM>, keeping the north pole and the south pole in the cylindrical faces.

In various embodiments, each recess <NUM> may extend between the inner cylindrical face <NUM> and the outer cylindrical face <NUM> of the magnet <NUM>. To maintain optimal magnetic strength, it may be desirable to space the segments closer together, reducing recess width. In various embodiments, the magnet <NUM> may comprise at least one recess or no recess at all. In various embodiments, the magnet <NUM> may be a continuous, annular magnet.

As shown in <FIG>, the magnet <NUM> is configured to induce a magnetic flux circuit <NUM>. In various embodiments, the magnetic flux circuit <NUM> may comprise a plurality of closed loop paths containing a magnetic flux. In various embodiments, and in further reference to <FIG>, <FIG>, and <FIG>, the magnetic flux circuit <NUM> may originate from the inner cylindrical face <NUM> of the magnet <NUM>, flow through the inner body <NUM> and up the poppet <NUM>, traverse the air gap into the magnetic shoulder portion <NUM> of the inlet fitting body, flow down the inner body <NUM> and into the outer body <NUM>, and terminate at the outer cylindrical face <NUM> of the magnet <NUM>.

In various embodiments, the inner body <NUM>, the outer body <NUM>, the poppet <NUM>, and the shoulder portion <NUM> of the inlet fitting body <NUM> may be comprised of magnetically permeable materials, such as, for example, soft iron, iron, cobalt, steel, chromium steel, ferro-magnetic stainless steel, and the like. In various embodiments, the collar portion <NUM> of the inlet fitting body <NUM> may be comprised of non-magnetic materials, such as, for example, austenitic chromium-nickel stainless steel and low carbon versions thereof, and the like. In various embodiments, the magnet <NUM> may be comprised of, for example, samarium cobalt, or any other suitable magnet material. In various embodiments, the polymer seal <NUM> may be comprised of soft polymer materials, such as, for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene, and the like.

In various embodiments, the magnetic flux circuit <NUM> may be fixed by the magnet design and the reluctance or resistance in the flux path. The primary reluctance is due to the air gap length, or the space defined by the inner surface of the shoulder portion <NUM> and the poppet <NUM>. As shown in <FIG>, while traversing the air gap into the magnetic shoulder portion <NUM>, the flux generates opposing pole faces <NUM> across the air gap, generating magnetic force. Referring to <FIG>, in various embodiments, the magnetic force across the air gap may be configured to attract the poppet <NUM> to the inner surface of the shoulder portion <NUM>, closing the valve <NUM>. This magnetic force may close the valve <NUM> and may be configured to induce a compressive sealing stress of the polymer seal <NUM> against the inner face of the shoulder portion <NUM>, keeping the valve <NUM> in closed position and the poppet <NUM> in a seated position.

However, magnetic force generated by the magnetic flux circuit <NUM> is not the only force acting on the poppet <NUM>. In various embodiments, the pressure of the liquid water accumulating along and trapped by the semi-permeable membrane <NUM> may be influenced by the pressure differences between the light unit and the external environment. In various embodiments, and as shown in <FIG>, in response to the pressure force of the light unit exceeding the magnetic force, the light unit pressure may act on the trapped liquid along the poppet <NUM>, pushing the poppet <NUM> in the negative y direction along the y-y axis onto the seat <NUM> and out the seated position. This increases the air gap defined by the shoulder portion <NUM> and decouples the polymer seal <NUM> from the inner face of the shoulder portion <NUM>.

<FIG> illustrates a cross-section along the x-x axis of <FIG>. As shown, and in various embodiments, the inner body <NUM> may define a plurality of cavities <NUM>. In various embodiments, the cavities <NUM> may be configured to permit liquid water to drain from the upstream lighting housing. In further reference to <FIG> and <FIG>, <NUM> is later referred to as cavities. In various embodiments, while the valve <NUM> is in a closed position, and the poppet <NUM> is in a seated position, the liquid water may be blocked from entering the cavities by the polymer seal <NUM>. As the polymer seal <NUM> decouples from the inner face of the shoulder portion <NUM>, the liquid water may exit the valve <NUM> via the cavities <NUM>. The semi-permeable membrane <NUM> overlaying the channel <NUM> remains impermeable to liquid water. Thus, as the valve <NUM> opens and the poppet <NUM> moves in the negative y direction along the y-y axis of the inner body <NUM>, the cavities <NUM> may act as a primary liquid water drain, while the channel remains an air/water vapor exchange. When the valve is in the closed position, in various embodiments, the polymer seal <NUM> may prevent secondary leakage into the cavities <NUM>.

In general, and as shown in <FIG>, the poppet <NUM> may be transmitted linearly within the inner body <NUM> in response to a force acting upon it at the inner surface air gap. This force may be, for example, the pressure of the liquid water acting on the poppet or the magnetic force attracting the poppet to the inner surface of the shoulder portion.

<FIG> illustrate a particular benefit of the magnetically controlled fluid drain valve shown in previous figured. The magnetic force is proportional to the pole face area and the square of the magnetic flux density available across the air gap. As demonstrated in <FIG>, as the air gap defined by the shoulder portion <NUM> increases, pushing the valve <NUM> open from the closed position, the magnetic force across the air gap decreases. As liquid water is vented into the external environment as the valve <NUM> is open, the pressure within the lighting unit may equalize with that of the external environment, reducing the pressure force within the lighting unit and valve <NUM> relative to that of the magnetic force generated by the magnetic flux circuit <NUM>. As the magnetic force exceeds the pressure acting on the poppet <NUM>, the magnetic force generated by the magnetic flux circuit <NUM> traversing across the air gap attracts the poppet <NUM> back to the inner face of the shoulder portion <NUM>, reducing the size of the air gap. The magnetic force continues to increase as the air gap decreases, urging the polymer seal <NUM> into the inner face of the shoulder portion <NUM> and inducing compressive stress once more.

Furthermore, as shown in <FIG>, it may be desirable to choose a seat <NUM>, or spring, that may exert de minimus force onto the poppet <NUM>, especially as the poppet <NUM> moves in the negative y direction along the y-y axis within the inner body <NUM> as the valve <NUM> opens. If the seat force acting on the poppet <NUM> as the valve opens were to exceed the minimum magnetic force, then the seat <NUM>, rather than the magnet <NUM> would determine when the valve closes. This may be less desirable, since the seat <NUM> may force the valve <NUM> closed before all the liquid water is drained. For example, in a typical spring-based valve, as the valve opens, a spring with a high spring rate is more likely to close the valve shut before the water drains. The spring constant of a given coil spring, rather than the pressure within the light unit, would determine the timing of valve closure.

Conversely, in relying on magnetic force tied to the pressure within the lighting unit, the valve <NUM> may stay open longer as the pressure between the lighting unit and the external environment equalizes, increasing the likelihood that the liquid water is fully drained. In sum, as the air gap increases, the magnetic force decreases, ensuring that less force will oppose the poppet <NUM> as the valve opens, and effectively creating a negative spring rate to keep the valve <NUM> open longer. The relationship between the lighting unit pressure and the magnetic force determines the timing of valve actuation (i.e., opening and closing), rather than any force exerted by the seat <NUM>.

<FIG> illustrates a method <NUM> of assembling the valve <NUM>. As shown, and in further reference to <FIG>, the method <NUM> comprises assembling <NUM> a poppet <NUM>. The poppet <NUM> comprises a poppet stem defining a channel <NUM>. In various embodiments, the channel <NUM> may be configured to permit at least one of air and water vapor to pass therethrough. The poppet <NUM> further comprises a planar face <NUM> defining an annular groove. Assembling <NUM> the poppet <NUM> further comprises installing <NUM> a polymer seal <NUM> within the annular groove. The polymer seal <NUM> is an O-ring. Assembling <NUM> the poppet <NUM> further comprises overlaying <NUM> the channel <NUM> with a semi-permeable membrane <NUM>. The semi-permeable membrane <NUM> is configured to permit at least one of air and water vapor to pass into the channel <NUM>, and is further configured to be impermeable to liquid water. The liquid water may accumulate along the membrane <NUM>.

The method of assembling <NUM> the valve comprises placing <NUM> a seat <NUM> within an inner body <NUM> of the valve <NUM>. The method <NUM> further comprises disposing <NUM> the poppet <NUM> onto the seat <NUM> within the inner body <NUM>. The seat <NUM> is configured to support the poppet <NUM>. The inner body <NUM> is configured to house the poppet <NUM> and the seat <NUM>. The method <NUM> further comprises setting <NUM> the inner body <NUM> within an outer body <NUM> The outer body <NUM> is configured to ring the inner body <NUM>. Setting <NUM> the inner body <NUM> within the outer body <NUM> defines a recess between the inner body <NUM> and the outer body <NUM>. The method of assembling <NUM> the valve further comprises disposing <NUM> a permanent magnet <NUM> within the recess between the inner body <NUM> and the outer body <NUM>. In further reference to <FIG>, the magnet <NUM> further comprises an inner cylindrical face <NUM> having a north pole and an outer cylindrical face <NUM> having a south pole.

The method of assembling <NUM> the valve <NUM> further comprises enclosing <NUM> the valve <NUM> with an inlet fitting body <NUM>. The inlet fitting body <NUM> is configured to cover the inner body <NUM>, the magnet <NUM>, and the outer body <NUM>. The inlet fitting body <NUM> comprises a shoulder portion <NUM> and a collar portion <NUM>. In various embodiments, the shoulder portion <NUM> may comprise an inner surface that at least partially defines an air gap <NUM>. In various embodiments, the collar portion <NUM> may at least partially define a lighting cavity <NUM>. In various embodiments, the collar portion may be configured to couple to a lighting housing of a lighting unit at the lighting cavity.

Claim 1:
A valve for an exterior aircraft light unit, the valve comprising:
an inlet fitting body (<NUM>) having a non-magnetic collar portion (<NUM>) and a magnetic shoulder portion (<NUM>), wherein the non-magnetic collar portion at least partially defines a lighting cavity (<NUM>), wherein the magnetic shoulder portion comprises an inner surface;
an outer body (<NUM>);
an inner body (<NUM>) disposed within the outer body (<NUM>), the inner body comprising:
a poppet (<NUM>) disposed between the inner surface of the shoulder portion and a seat (<NUM>), wherein the inner surface of the magnetic shoulder portion (<NUM>) faces the inner body and the poppet;
wherein the seat is configured to support the poppet; an air gap (<NUM>) extending between the magnetic shoulder portion inner surface and
the poppet;
a polymer seal (<NUM>) retained within an annular groove of the poppet, wherein the polymer seal is configured to couple the poppet to the inner surface of the shoulder portion of the inlet fitting body; and
a permanent magnet (<NUM>) disposed between the inner body and an outer body of the valve, wherein the magnet further comprises an inner cylindrical face (<NUM>) having a north pole and an outer cylindrical face (<NUM>) having a south pole, the outer cylindrical face (<NUM>) being radially opposite the inner cylindrical face (<NUM>),
wherein the magnet of the valve is configured to induce a magnetic flux circuit (<NUM>), wherein the magnetic flux circuit induced by the magnet comprises a plurality of closed loop paths containing a magnetic flux, wherein the magnetic flux originates from the inner cylindrical face (<NUM>) of the magnet, flows through the inner body and up the poppet, traverses the air gap into the magnetic shoulder portion of the inlet fitting body, flows down the inner body and into the outer body, and terminates at the outer cylindrical face (<NUM>) of the magnet.