Patent Description:
A labyrinth barrier operates as a non-contact seal between two adjacent compartments. For example, when used in a thrust reverser for an aircraft, the labyrinth barrier creates a torturous pathway that restricts fluid located in an engine core compartment from flowing into another thrust reverser compartment. Specifically, the labyrinth barrier creates an alternate circumferential pathway that is of lower resistance when compared to the axial pathway that otherwise connects the thrust reverser compartments. Therefore, the fluid naturally flows from the engine core compartment towards the alternate pathway provided by the labyrinth barrier. Alternate configurations rely primarily on vortex formation as opposed to flow redirection.

The labyrinth barrier includes multiple elongated members arranged in a staggered pattern. It is to be appreciated that a clearance exists between the members, which creates an imperfect seal. The clearance allows the members to interlock with one another without contacting one another or creating damage when the labyrinth barrier is opened or closed. However, if the clearance is too large, then there is less flow restriction, which in turn reduces the overall effectiveness of the labyrinth barrier. In contrast, if the clearance is too small, then other issues may arise. For example, the individual members of the labyrinth barrier may rub or otherwise contact one another. The contact between the members may create structural issues as well as compromise the effectiveness of the labyrinth barrier.

In another approach, a turkey feather seal may be used instead of a labyrinth barrier in a thrust reverser. A turkey feather seal includes multiple flexible metal segments that overlap one another. The segments deform slightly and directly contact the engine exhaust. However, the environment around the engine is very dynamic and experiences a significant amount of vibration, which in turn adversely affects the turkey feather seal.

<CIT> in an abstract states that "An improved seal assembly for use with a combustion liner assembly is employed with a gas turbine engine so as to control fluid flow. The seal assembly has a bi-metal sealing member that is affixed to a first surface that is proximal to a second perpendicular surface that is not in contact with the first surface, thus providing a potential fluid flow path. Upon heating, the bi-metal sealing member "uncoils" contacting the second perpendicular surface, thus blocking the flowpath between the two surfaces. Various metals may be provided to provide predetermined sealing characteristics.

<CIT> in an abstract states that "A high temperature component having an actuator body <NUM> including an actuatable portion comprising a shape memory alloy containing one more of Ni, Al, Nb, Ti and Ta and a platinum-group metal. The shape memory alloy has an altered geometry at a predetermined temperature. The actuator body <NUM> is also capable of operation in and is resistant to high temperature oxidizing atmospheres. A method for forming an actuator and a method for high temperature control are also disclosed.

<CIT> in an abstract states that "PURPOSE: To constitute a holder integrally on the fixed side of shaft-through part of an electric rotating machine by composing a labyrinth seal piece of a shape memory alloy. CONSTITUTION: A plurality of fixed side labyrinth seal pieces <NUM> made of shape memory alloy are planted on a holder <NUM> whereas a plurality of rotary side labyrinth seal pieces <NUM> made of shape memory alloy are planted on a shaft <NUM>, and then the labyrinth seal pieces <NUM>, <NUM> are cooled to be bent axially. The integrally constituted holder <NUM> is then inserted, axially from the right side, into a shaft <NUM> with the fixed side labyrinth seal piece <NUM> being bent thus securing the holder in place. When heated lubricant or steam is fed to a shaft-through part constituted in such a manner, the holder <NUM> and the shaft <NUM> are heated while furthermore the fixed side labyrinth seal piece <NUM> and the rotary side labyrinth seal piece <NUM> are heated and recovered to the original shape and project radially.

<CIT> in a translation of its title refers to a labyrinth seal.

According to several aspects, a labyrinth barrier is disclosed. The labyrinth barrier comprises two or more members each defining respective vertical axes, where one or more of the members are constructed at least in part of a shape memory material having a first energy state and a second energy state. The members are oriented relative to one another by their respective vertical axes in an original state to create a flow pathway that restricts fluid flow in a direction transverse to the respective vertical axes, and the members are urged towards one another to further restrict the flow pathway when the shape memory material transitions from the first energy state to the second energy state.

In another aspect, a labyrinth barrier disposed along two opposing walls is disclosed. The labyrinth barrier comprises two or more members each defining respective vertical axes, where each member includes a proximate end and a distal end, and the proximate end of each of the members is attached to one of the two opposing walls. The members are oriented relative to one another by their respective vertical axes in an original state to create a flow pathway that restricts fluid flow in a direction transverse to the respective vertical axes. The labyrinth barrier also includes an arm corresponding to one or more of the members that are constructed at least in part of a shape memory material having a first energy state and a second energy state. The arm is fixedly attached to a corresponding member and actuates as the shape memory material transitions from the first energy state to the second energy state to urge a distal end of the corresponding member towards the distal end of an adjacent member to further restrict the flow pathway when the shape memory material transitions from the first energy state to the second energy state.

In yet another aspect, method for limiting flow by a labyrinth barrier is disclosed. The method includes creating a flow pathway by two or more members of the labyrinth barrier. Each member defines a respective vertical axis and one or more of the members are constructed at least in part of a shape memory material having a first energy state and a second energy state. The method also includes restricting fluid flow in a direction transverse to the respective vertical axes of the members. The method also includes bringing the shape memory material of one or more of the members to a transition temperature of the shape memory material. The method also includes urging the members towards one another to further restrict the flow pathway as the shape memory material transitions from the first energy state to the second energy state.

The features, functions, and advantages that have been discussed may be achieved independently in various examples or may be combined in other examples, further details of which can be seen with reference to the following description and drawings.

The present disclosure is directed towards a labyrinth barrier having two or more members that are constructed at least in part from a shape memory material, where each member defines a respective vertical axis. The shape memory material includes a first energy state and a second energy state, where the shape memory material transitions from the first energy state into the second energy state at a transition temperature. It is to be appreciated that the first energy state may be a high energy state or a low energy state, depending upon the application, and the second energy state depends upon the specific first energy state that is selected. The members are oriented relative to one another by their respective vertical axes in an original state to create a flow pathway that restricts fluid flow in a direction transverse to the respective vertical axes. The members are urged towards one another to further restrict the flow pathway when the shape memory material transitions from the first energy state to the second energy state.

Referring to <FIG>, a portion of a thrust reverser <NUM> for an aircraft <NUM> is shown. The thrust reverser <NUM> includes a thrust reverser compartment <NUM> and a labyrinth barrier <NUM>. The thrust reverser compartment <NUM> is defined, in part, by an upper wall <NUM> and a lower wall <NUM>. The labyrinth barrier <NUM> is positioned between the thrust reverser compartment <NUM> and an engine core compartment <NUM>. As seen in <FIG>, the thrust reverser compartment <NUM> is located directly adjacent to the engine core compartment <NUM>. A flow pathway <NUM> is shown, where the flow pathway <NUM> originates within the engine core compartment <NUM>, flows through the labyrinth barrier <NUM>, and into the compartment <NUM> of the thrust reverser <NUM>. The labyrinth barrier <NUM> includes two or more elongated members <NUM>. One or more of the members <NUM> of the labyrinth barrier <NUM> are constructed at least in part of a shape memory material <NUM> (seen in <FIG>) having a first energy state and a second energy state. As explained below, the labyrinth barrier <NUM> is configured to either restrict the flow pathway <NUM> or, alternatively, to act as an anti-fire barrier by blocking the flow pathway <NUM> when the shape memory material <NUM> transitions from the first energy state to the second energy state. In the example as shown in <FIG>, the labyrinth barrier <NUM> is an anti-fire barrier configured to prevent a flame or flammable fluid that originates within the engine core compartment <NUM> from entering the thrust reverser compartment <NUM>.

Although <FIG> illustrates a thrust reverser <NUM>, it is to be appreciated that the labyrinth barrier <NUM> may be used in a variety of other applications and is not limited to the example as shown in <FIG>. Moreover, the disclosed labyrinth barrier <NUM> is also not limited to an aircraft and may be used in any application where a barrier is required to create a pressure gradient or to restrict flow. For example, in one example, the disclosed labyrinth barrier <NUM> is employed in a vacuum tube train, which is sometimes referred to as a hyperloop train.

<FIG> is an enlarged view of the labyrinth barrier <NUM>. In the exemplary example as shown, the labyrinth barrier <NUM> includes four members <NUM> arranged in a staggered pattern along two opposing surfaces <NUM>, <NUM>. Specifically, two members 32A are attached to an upper surface <NUM> of the upper wall <NUM> and two remaining members 32B are attached to a lower surface <NUM> of the lower wall <NUM>, where alternating members <NUM> of the labyrinth barrier <NUM> are attached to the same surface <NUM>, <NUM>. Accordingly, the members <NUM> are arranged to create a flow pathway <NUM> having a winding configuration that restricts the flow between the two adjacent compartments <NUM>, <NUM>. Each member <NUM> includes a proximate end <NUM> and a distal end <NUM>, where the members <NUM> are attached to either the upper surface <NUM> or the lower surface <NUM> at their respective proximate ends <NUM>.

In an example, one or more of the members <NUM> of the labyrinth barrier <NUM> are constructed entirely from the shape memory material <NUM>. For example, in the non-limiting example as shown in <FIG>, the members <NUM> are each constructed entirely from the shape memory material <NUM>. However, as seen in <FIG>, <FIG>, in another example only a portion of the members <NUM> are constructed from the shape memory material <NUM>, and a remaining portion of the members <NUM> are constructed from another material such as, for example, steel, titanium, copper nickel alloys, or composite materials. The shape memory material <NUM> includes shape memory alloy, a shape memory ceramic, and a shape memory polymer. Some examples of shape memory alloys include, but are not limited to, nickel titanium alloys or nickel copper aluminum alloys. Some examples of shape memory polymers include, but are not limited to, polytetrafluoroethylene (PFTE), polylactide (PLA), and ethylene-vinyl acetate (EVA). As mentioned above, the shape memory material <NUM> includes the first energy state and the second energy state. Depending upon the application, the first energy state is either a low energy state or a high energy state. The low energy state may be referred to as the martensitic state and the high energy state may be referred to as the austenitic state for a shape memory alloy.

As explained below, the members <NUM> of the labyrinth barrier <NUM> are urged towards one another to restrict the flow pathway <NUM> when the shape memory material <NUM> transitions from a first energy state to a second energy state. The first energy state may be either the high energy state or the low energy state, depending upon the specific application. As seen in the <FIG>, the members <NUM> each define a respective vertical axes A that extend along a length L the respective member <NUM>. The members <NUM> are illustrated in <FIG> in an original state, before the shape memory material <NUM> transitions from the first energy state to the second energy state. For example, if the labyrinth barrier <NUM> is part of the thrust reverser <NUM> shown in <FIG>, then the member <NUM> are in the original state before the engines (not shown) of the aircraft <NUM> are operating and produce the heat.

Referring to both <FIG> and <FIG>, the members <NUM> are oriented relative to one another by their respective vertical axes A in the original state to create the flow pathway <NUM>. As seen in <FIG>, a fluid <NUM> that originates from the engine core compartment <NUM> that flows towards the thrust reverser compartment <NUM> is oriented in a direction transverse to the respective vertical axes A of the members <NUM>. In the non-limiting example as shown in <FIG>, the members <NUM> are each oriented parallel to one another with respect to their vertical axes A when in the original state. However, it is to be appreciated that the members <NUM> may also be oriented in other arrangements as well.

<FIG> is an enlarged view of two adjacent members <NUM> of the labyrinth barrier <NUM>, where the original state is shown in solid lines and a position of the members <NUM> after the shape memory material <NUM> has transitioned from the first energy state to the second energy state is shown in phantom line. The phantom lines illustrate the members <NUM> being urged towards one another to restrict the flow pathway <NUM> when the shape memory material <NUM> transitions from the first energy state to the second energy state. Referring to both <FIG> and <FIG>, in an example the members <NUM> are oriented parallel to one another with respect to their vertical axes A after the shape memory material <NUM> transitions from the first energy state to the second energy state as well. In one example, the members <NUM> are urged towards one another when the shape memory material <NUM> transitions from the low energy state to the high energy state. Alternatively, in another example, the members <NUM> are urged towards one another when the shape memory material <NUM> transitions from the high energy state to the low energy state.

The shape memory material <NUM> transitions from the first energy state to the second energy state at an activation temperature. In one example, the members <NUM> are heated to the activation temperature of the shape memory material <NUM>, where the shape memory material <NUM> transitions from the low energy state to the high energy state. For purposes of this disclosure, when the shape memory material <NUM> is heated, this does not necessarily require subjecting the shape memory material <NUM> to temperatures that are above normal room temperature, which ranges from about twenty to twenty-two degrees Celsius (<NUM>-<NUM>°F). Instead, the activation temperature of some types of shape memory materials may be at or below room temperature. Alternatively, in another example, the members <NUM> are cooled or reduced in temperature to the activation temperature, where the shape memory material <NUM> transitions from the high energy state to the low energy state. For purposes of this disclosure, when the shape memory material <NUM> is cooled, this does not necessarily require subjecting the shape memory material <NUM> to temperatures that are less than normal room temperature. It is to be appreciated that the members <NUM> return to the original state when the shape memory material <NUM> transitions from the second energy state back to the first energy state.

Referring to <FIG>, when in the original state, the members <NUM> of the labyrinth barrier <NUM> are positioned to create a gap or clearance C. The clearance C is defined as a required distance between two members <NUM> that are adjacent to one another when in the original state. The clearance C is sized to ensure the members <NUM> do not contact one another during fabrication and installation, or during the life of the labyrinth barrier <NUM> because of environmental concerns such as, but not limited to, thermal expansion or vibration. The clearance C is selected based on factors such as, but not limited to, an amount of flow restriction required in the original state, manufacturing tolerances, installation tolerances, vibrations experienced in the immediate vicinity of the labyrinth barrier <NUM>, and thermal expansion. For example, installation tolerances allow for the thrust reverser <NUM> (<FIG>) to be opened and closed without having the members <NUM> contact one another. It is to be appreciated that the clearance C may be greater than the usual clearance that exists between adjacent members in a conventional labyrinth barrier, which is advantageous as this allows for more room during manufacturing and installation.

In one example, the shape memory material <NUM> is in the low energy state when the members <NUM> are in the original position, the labyrinth barrier <NUM> is an anti-fire barrier, and the shape memory material <NUM> is in the low energy state when the members <NUM> are in the original position. During operation of the aircraft <NUM>, the members <NUM> are heated to the activation temperature of the shape memory material <NUM>. In the present example, the activation temperature is indicative of a flame present in an area adjacent to the labyrinth barrier <NUM>. For example, in the example as shown in <FIG>, the adjacent area is the engine core compartment <NUM>. Therefore, the members <NUM> are urged towards and contact one another, and the clearance C between two adjacent members <NUM> is eliminated. As a result, the flow pathway <NUM> is blocked. However, in some applications where the labyrinth barrier <NUM> is not an anti-fire barrier, the members <NUM> do not contact one another, and the clearance C is reduced but not eliminated.

In another approach, only a portion of the members <NUM> that are part of the labyrinth barrier <NUM> are constructed of the shape memory material. <FIG> are a perspective view of another example of one of the members <NUM> of the labyrinth barrier <NUM>. In the example as shown in <FIG>, the member <NUM> defines a respective cross-sectional profile <NUM>. The cross-sectional profile <NUM> includes two legs 152A, 152B. One of the legs 152A of the member <NUM> is attached to a structure, such as the upper wall <NUM> or the lower wall <NUM> of the thrust reverser <NUM> shown in <FIG>. One or more shape memory segments <NUM> constructed of the shape memory material <NUM> extends along the respective cross-sectional profile <NUM> of the member <NUM>. The shape memory segments <NUM> are wires, ribbons, or sheets of the shape memory material <NUM>. In the example as shown in <FIG>, the shape memory segments <NUM> are embedded within the member <NUM>. In one example, the shape memory segments <NUM> are attached to the member <NUM>. The shape memory segments <NUM> may be attached to the member <NUM> using a variety of approaches. For example, the shape memory segments <NUM> may be mechanically fastened, bonded to, or embedded within the member <NUM>.

<FIG> illustrates the member <NUM> in the original state, where the legs 152A, 152B are oriented at an angle a relative to one another. In the example as shown in <FIG>, the angle a is ninety degrees, and the members <NUM> are perpendicular to one another. Although <FIG> illustrates the legs 152A, 152B oriented perpendicular to one another, it is to be appreciated that <FIG> is merely exemplary in nature, and the legs 152A, 152B may be oriented relative to one another in a variety of configurations. Once the shape memory material <NUM> reaches the respective transition temperature, the shape memory material <NUM> transitions from the first energy state to the second energy state, and the leg 152B is actuated either towards or away from the other leg 152A. In the example as shown in <FIG>, the leg 152B is urged towards the remaining leg 152A, thereby reducing the angle a.

<FIG> illustrate yet another example of the labyrinth barrier <NUM>, where at least one of the members <NUM> include a shape memory torque tube <NUM> constructed of the shape memory material <NUM>. Specifically, in the example as shown, the shape memory torque tube <NUM> is located at the distal end <NUM> of the respective member <NUM>. <FIG> illustrates the members <NUM> in the original state. Once the shape memory material <NUM> reaches the transition temperature, the shape memory torque tube <NUM> transmits a torsional force T (<FIG>), thereby actuating the members <NUM> towards one another, which is shown in <FIG>.

In still another example shown in <FIG>, the members <NUM> are constructed from a material other than the shape memory material <NUM>. Instead, the members <NUM> are actuated or urged towards one another using a respective arm <NUM> constructed of the shape memory material <NUM>. In the example as shown, two adjacent members <NUM> are disposed along two opposing walls <NUM>, <NUM>. The members <NUM> each include a proximate end <NUM> and a distal end <NUM>, where the proximate end <NUM> of the member <NUM> is attached a respective wall <NUM>, <NUM>. The arms <NUM> also include a respective proximate end <NUM> and a respective distal end <NUM>, where a distal end <NUM> of a corresponding arm <NUM> is attached to the distal end <NUM> of the member <NUM>. The arms <NUM> are each fixedly attached to a respective wall <NUM>, <NUM> at the proximate end <NUM>.

In the example as shown, each arm <NUM> corresponds to a member <NUM>. The arm <NUM> is constructed at least in part of the shape memory material <NUM>, where the arm <NUM> is fixedly attached to a corresponding member <NUM>. As seen in <FIG>, the arm actuates as the shape memory material <NUM> transitions from the first energy state to the second energy state to urge the distal end <NUM> of the corresponding member <NUM> towards the distal end <NUM> of an adjacent member <NUM> to further restrict the flow pathway <NUM> (seen in <FIG>) when the shape memory material transitions from the first energy state to the second energy state.

<FIG> is an exemplary process flow diagram of a method <NUM> for actuating the labyrinth barrier <NUM>. Referring generally to <FIG>, the method <NUM> begins at block <NUM>. In block <NUM>, the flow pathway <NUM> (<FIG>) is created by two or more members <NUM> each defining a respective vertical axis, where one or more of the members <NUM> are constructed at least in part of the shape memory material <NUM>. The method <NUM> may then proceed to block <NUM>.

In block <NUM>, the flow pathway <NUM> (<FIG>) restricts fluid flow in a direction transverse to the respective vertical axes A of the members <NUM>. In block <NUM>, the members <NUM> are in the original state. The method <NUM> may then proceed to block <NUM>.

In block <NUM>, the shape memory material <NUM> of one or more of the members <NUM> is brought to the transition temperature. The shape memory material <NUM> may be heated or, alternatively, cooled to the transition temperature. The method <NUM> may then proceed to block <NUM>.

In block <NUM>, the members <NUM> are urged towards one another to further restrict the flow pathway <NUM> as the shape memory material transitions from the first energy state to the second energy state. The method <NUM> may then proceed to block <NUM>.

It is to be appreciated that block <NUM> is optional and is used when the labyrinth barrier <NUM> is an anti-fire barrier. In block <NUM>, the members <NUM> are urged towards one another to block the flow pathway <NUM>, which is shown in <FIG>. The method <NUM> may then terminate.

Referring generally to the figures, the disclosed labyrinth barrier provides various technical effects and benefits. Specifically, a clearance exists between the members of the labyrinth barrier, and the clearance is sized as to ensure the members do not contact one another during fabrication and installation, or during the life of the labyrinth barrier <NUM> because of thermal expansion or vibration. However, once the shape memory material of the members transitions from the first energy state to the second energy state, the members of the labyrinth barrier are urged towards one another to further restrict flow. Accordingly, the members of the disclosed labyrinth barrier are dimensioned to avoid contact issues between the members in the original state, but the shape memory material allows for the members to still be able to block fluid flow when required. Therefore, the disclosed labyrinth barrier overcomes some of the issues faced by conventional barriers by providing sufficient clearance during fabrication, installation, or during operation, while also restricting or blocking the flow of fluid as the shape memory material transitions between phases as well.

Claim 1:
A system comprising a labyrinth barrier (<NUM>) and two opposing walls, the system comprising:
two or more members (<NUM>) each defining respective vertical axes, wherein the members (<NUM>) are constructed at least in part of a shape memory material (<NUM>) having a first energy state and a second energy state, and the members (<NUM>) are oriented relative to one another by their respective vertical axes in an original state to create a flow pathway (<NUM>) that restricts fluid flow in a direction transverse to the respective vertical axes, whereby two adjacent members are disposed along the two opposing walls, the adjacent members (<NUM>) are urged towards one another to further restrict the flow pathway (<NUM>) when the shape memory material (<NUM>) transitions from the first energy state to the second energy state.