Patent Description:
Attritable aircraft can include, for example, Unpiloted (or Unmanned) Aerial Vehicles (UAVs) and expendable turbojet systems for guided munitions, missiles, and decoys. Attritable aircraft are generally designed as a limited lifetime vehicle, which can be as short as a single use or single mission vehicle. As such, many components and features common in traditional piloted aircraft are unnecessary, such as, a fluid dispensing system within a traditional aircraft engine. The fluid dispensing system can have five or more individual parts, each requiring assembly, which can be expensive and time consuming.

Filters are an important part of the lubrication system because they remove foreign particles that may be in the lubricating fluid. This is particularly important in gas turbines as very high engine speeds are attained; the antifriction types of ball and roller bearings would become damaged quite rapidly if lubricated with contaminated fluids. Also, there are usually numerous drilled or core passages leading to various points of lubrication. Since these passages are usually rather small, they are easily clogged.

Additionally, metering the lubrication fluid is important. On the one hand, enough lubrication fluid needs to be provided such that sufficient cooling of the bearings are achieved under all working conditions of the gas turbine engine. On the other hand, too much lubrication fluid may require larger fluid pumps and piping system than necessary, increasing the footprint of the lubrication system. Also, pumping unnecessary lubrication fluid through the system uses energy that could be used elsewhere in the gas turbine engine. As such, providing too much lubrication fluid results in a less efficient gas turbine engine compared to a gas turbine engine provided with a proper amount of lubrication fluid.

<CIT> discloses a self-cleaning debris filter for a fan drive gear system comprising a screen positioned in a lubrication flow pathway between a fluid filtering inlet and a fluid filtering outlet.

In accordance with a first aspect of the disclosure, there is a lubrication system as claimed in claim <NUM>.

In accordance with a second aspect of the disclosure, there is a method of manufacturing an attritable engine lubrication system as claimed in claim <NUM>.

An attritable engine with an integrally built fluid dispensing system simplifies manufacturing. Even so, an attritable engine can leverage additive manufacturing techniques to improve various aspects of the limited-life engine. For example, additive manufacturing allows the assembly details to be unitized and, simultaneously permits integration of many complex performance-enhancing features. The additively manufactured engine reduces the time to delivery to the customer and lowers the overall production costs of the unit.

Disclosed herein is a lubrication system having an integrated lattice network of spars placed in a lubrication flow pathway. The lattice filters a fluid in a gas turbine engine and the fluid is metered by a metering port located downstream of the lattice. The lattice is built using additive manufacturing techniques such as, for example, laser powder bed fusion, electron beam melting, and glue binder jetting.

<FIG> is a cross-sectional view of an attritable engine. <FIG> shows attritable engine <NUM> including compressor section <NUM>, turbine section <NUM>, exhaust section <NUM>, combustor <NUM>, rotor <NUM>, bearings <NUM> and <NUM>, compressor blades <NUM>, turbine blades <NUM>, and axis of rotation X. In the illustrated embodiment, attritable engine <NUM> shows compressor section <NUM> lying forward and adjacent to turbine section <NUM>, which is positioned forward of exhaust section <NUM>. Although combustor <NUM> lies physically aft of turbine section <NUM>, combustor <NUM> fluidically sits between compressor section <NUM> and turbine section <NUM>. This arrangement may be referred to as a reverse flow combustor. Rotor <NUM> extends along the axis of rotation X into both compressor section <NUM> and turbine section <NUM>. Rotor <NUM> is received in bearings <NUM> and <NUM>. Attached to rotor <NUM> are compressor blades <NUM> and turbine blades <NUM>.

Operationally, air enters the forward end of compressor section <NUM> and is compressed by compressor blades <NUM>. Compressed air along with fuel enters combustor <NUM> where the compressed air and fuel are combusted. The combusted fuel and compressed air from combustor <NUM> enters turbine section <NUM> and turns turbine blades <NUM> circumferentially around rotational axis X, which generates power by also turning rotor <NUM>. The air exits out of the aft end of exhaust section <NUM>.

<FIG> will be discussed together. <FIG> is a regional sectional view from attritable engine <NUM> in <FIG>. <FIG> shows attritable engine <NUM> including compressor section <NUM>, rotor <NUM>, bearings <NUM> and <NUM>, compressor blades <NUM>, lubrication system <NUM>, fluid manifold <NUM>, fluid filtering inlet <NUM>, fluid filtering outlet <NUM>, lattice <NUM> and metering port <NUM>. <FIG> is another cross-sectional view of the attritable engine including a metering device integrated into the fuel path. <FIG> shows attritable engine <NUM> including lubrication system <NUM>, fluid manifold <NUM>, fluid filtering inlet <NUM>, fluid filtering outlet <NUM>, lattice <NUM>, metering port <NUM>, and fluid distribution rail <NUM>.

Lubrication system <NUM> provides fluid to bearings <NUM> and <NUM> from a fluid source such as, for example, a fuel tank or an oil tank. Fluid can be any fluid that provides cooling to bearings <NUM> and <NUM> such as, for example, fuel and oil. Fluid enters lubrication system <NUM> from a fluid source at fluid manifold <NUM>, which distributes fluid to fluid filtering inlet <NUM>. Fluid manifold <NUM> can distribute fluid to more than one fluid filtering inlet <NUM> through fluid distribution rail <NUM>, shown in <FIG>. Fluid distribution rail <NUM> circumferentially travels around the engine casing. Fluid distribution rail <NUM> may travel all the way around the engine casing or only partially around the engine casing and distribute fluid to multiple fluid filtering inlets <NUM>.

Fluid exits lubrication system <NUM> at fluid filtering outlet <NUM> and is then distributed to components within attritable engine <NUM> in need of lubrication such as bearings <NUM> and <NUM>. Lattice <NUM> is located between fluid filtering inlet <NUM> and fluid filtering outlet <NUM>. Lattice <NUM> is formed of a repeating pattern of spars that filters the fluid. Metering port <NUM> meters the fluid flow rate through fluid distribution system <NUM> and is located downstream of lattice <NUM> and upstream of fluid filtering outlet <NUM>. Fluid distribution system <NUM> can be formed of stainless steel. In other embodiments, fluid distribution system <NUM> can be formed of aluminum, titanium, copper, cobalt, iron, nickel, and alloys thereof.

<FIG> is a regional sectional view from the attritable engine in <FIG>. <FIG> shows lattice <NUM> of attritable engine <NUM> including spars <NUM>, and metering port <NUM>. Lattice <NUM> is formed of multiple spars <NUM>, which are arranged to filter a fluid passing through lattice <NUM>. In other words, particulates present in the fluid which are larger than the passages formed by the arrangement of spars <NUM> are selectively filtered out of the fluid. Spars are sized and oriented based on various factors such as filtering out particulates of a certain size present in the fluid and manufacturing considerations (some spars <NUM> sizes and orientations may be easier to manufacture than others). Metering port <NUM> is adjacent to and downstream of spars <NUM>. Metering port <NUM> can be sized to meter the flow rate of the fluid within a target range through fluid distribution system <NUM>.

<FIG> is a regional sectional view from the lattice in <FIG> shows lattice <NUM> of attritable engine <NUM> including spars 132A, 132B, 132E, and 132F. Spars 132C and 132D is obscured by the other spars in <FIG> and, as such, not shown in <FIG>. In the illustrated embodiment, there are six spars <NUM> radially extending from a center point at substantially <NUM>° angles to one another, forming a spar assembly. Multiple spar assemblies are formed adjacent one another and together form lattice <NUM>.

<FIG> is a perspective view of another embodiment of the repeating lattice structure. <FIG> shows spar assembly <NUM> including spars 132A, 132B, 132C, 132D, 132E, and 132F, and center point <NUM>. In the illustrated embodiment, there are six spars <NUM> radially extending from a center point <NUM>. Adjacent spars <NUM>, for example spars 132A and 132B, lie at substantially <NUM>° angles to one another. The ends of any three adjacent spars <NUM>, for example spars 132A, 132B, and 132E, which are at an opposing end to center point <NUM>, can form an abstract triangle. Taking all eight sets of three adjacent spars <NUM> and the resulting abstract triangle from each set of three adjacent spars <NUM> forms an abstract <NUM>-dimensional shape, which can referred to as a square bipyramid.

Each spar <NUM> can have, for example, a diameter of <NUM> inches (<NUM>). In other embodiments, each spar <NUM> can have a diameter from <NUM> inches (<NUM>) to <NUM> inches (<NUM>), inclusive. In other embodiments, each spar <NUM> can have a diameter smaller than <NUM> inches (<NUM>). In other embodiments, each spar <NUM> can have a diameter larger than <NUM> inches (<NUM>). Each spar <NUM> can have a length of <NUM> inches (<NUM>). In other embodiments, each spar <NUM> can have a length from <NUM> inches (<NUM>) to <NUM> inches (<NUM>), inclusive. In other embodiments, each spar <NUM> can have a length smaller than <NUM> inches (<NUM>). In other embodiments, each spar <NUM> can have a length larger than <NUM> inches (<NUM>).

In other embodiments, spar assembly <NUM> includes more than six spars <NUM>. In other embodiments, spar assembly <NUM> includes fewer than six spars <NUM>. In other embodiments, two adjacent spars <NUM> can lie at an angle more than <NUM>° from one another. In other embodiments, two adjacent spars <NUM> can lie at an angle from <NUM>° to <NUM>° from one another.

Lattice <NUM> is integral and conformal with attritable engine <NUM> and is manufactured using additive manufacturing techniques such as laser powder bed fusion, electron beam melting, and glue binder jetting.

A fluid dispensing system having an integrated lattice network of spars placed in a lubrication flow pathway unitizes and, simultaneously permits integration of many complex performance-enhancing features. Specifically, the lattice can filter a fluid used to cool the bearings in a gas turbine engine while a metering port can control the flow rate of the fluid through the fluid dispensing system.

A lubrication system for an attritable engine includes a bearing chamber, a fluid filtering inlet configured to receive a fluid, and a fluid filtering outlet located downstream of the fluid filtering inlet and configured to deliver the fluid to the bearing chamber. The lubrication system also includes a lattice, integral and conformal with the attritable engine, configured to filter the fluid, and located between the fluid filtering inlet and the fluid filtering outlet. The lubrication system also includes a metering port, configured to meter the fluid and located downstream of the lattice and upstream of the fluid filtering outlet.

The system of the preceding paragraph can optionally include, additionally and/or alternatively any one or more of the following features, configurations or additional components:
The lattice is formed of a repeated pattern of spar assemblies.

The spar assembly has a square bipyramid shape.

The spars have a diameter from <NUM> inches (<NUM>) to <NUM> inches (<NUM>), inclusive.

The spars have a length from <NUM> inches (<NUM>) to <NUM> inches (<NUM>), inclusive.

The fluid filtering inlet, the fluid filtering outlet, the metering port, and the lattice are formed from a member of the group selected from aluminum, titanium, copper, cobalt, iron, nickel, nickel alloys, stainless steel, and combinations thereof.

The fluid is fuel for a gas turbine engine.

The lattice is built in a layer by layer process using additive manufacturing techniques.

A method of manufacturing an attritable engine lubrication system includes manufacturing a bearing chamber, a fluid filtering inlet configured to receive a fluid, and a fluid filtering outlet located downstream of the fluid filtering inlet and configured to deliver the fluid to the bearing chamber. The method also includes manufacturing a lattice, integral and conformal with the attritable engine, configured to filter the fluid, and located between the fluid filtering inlet and the fluid filtering outlet. The method also includes manufacturing a metering port, configured to meter the fluid, and located downstream of the lattice and upstream of the fluid filtering outlet.

The method of the preceding paragraph can optionally include, additionally and/or alternatively any, one or more of the following features, configurations and/or additional components:
The lattice is formed of a repeated pattern of spar assemblies.

Claim 1:
A lubrication system (<NUM>) for an attritable aircraft gas turbine engine (<NUM>), the lubrication system (<NUM>) comprising:
a bearing chamber;
a fluid filtering inlet (<NUM>) configured to receive a fluid;
a fluid filtering outlet (<NUM>) located downstream of the fluid filtering inlet (<NUM>) and configured to deliver the fluid to the bearing chamber;
a lattice (<NUM>) positioned in a lubrication flow pathway between the fluid filtering inlet (<NUM>) and the fluid filtering outlet (<NUM>) and configured to filter the fluid, wherein the lattice (<NUM>) is formed of a repeated pattern of multiple spar assemblies (<NUM>) formed adjacent to one another and wherein each of the multiple spar assemblies (<NUM>) comprises a plurality of spars (132A, 132B, 132C, 132D, 132E, 132F) that are sized and oriented to filter particulates in the fluid; and
a metering port (<NUM>), configured to meter the fluid and located downstream of the lattice (<NUM>) and upstream of the fluid filtering outlet (<NUM>),
wherein the lattice (<NUM>) is an integrated lattice network of the spars (132A, 132B, 132C, 132D, 132E, 132F) and is additively manufactured such that it is integral with the attritable aircraft gas turbine engine (<NUM>).