Lubrication fluid collection in a gearbox of a gas turbine engine

An epicyclic gearbox assembly for a gas turbine engine includes a sun gear assembly; a planet gear assembly engaged with the sun gear assembly; and a ring gear assembly including one or more ring gears engaged with the planet gear assembly. The epicyclic gearbox assembly further includes a lubrication fluid collection assembly having a rotating oil scoop extending in a circumferential direction around the ring gear assembly, the rotating oil scoop coupled to the ring gear assembly at a location forward of one or more ring gears of the ring gear assembly.

FIELD

The present subject matter relates generally to a gearbox for a gas turbine engine, or more particularly, a gearbox for a gas turbine engine having a lubrication fluid collection assembly.

BACKGROUND

A gas turbine engine generally includes a fan and a core arranged in flow communication with one another with the core disposed downstream of the fan in the direction of the flow through the gas turbine. The core of the gas turbine engine generally includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. With multi-shaft gas turbine engines, the compressor section can include a high pressure compressor (HP compressor) disposed downstream of a low pressure compressor (LP compressor), and the turbine section can similarly include a low pressure turbine (LP turbine) disposed downstream of a high pressure turbine (HP turbine). With such a configuration, the HP compressor is coupled with the HP turbine via a high pressure shaft (HP shaft), and the LP compressor is coupled with the LP turbine via a low pressure shaft (LP shaft).

In operation, at least a portion of air over the fan is provided to an inlet of the core. Such portion of the air is progressively compressed by the LP compressor and then by the HP compressor until the compressed air reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section through the HP turbine and then through the LP turbine. The flow of combustion gasses through the turbine section drives the HP turbine and the LP turbine, each of which in turn drives a respective one of the HP compressor and the LP compressor via the HP shaft and the LP shaft. The combustion gases are then routed through the exhaust section, e.g., to atmosphere.

The LP turbine drives the LP shaft, which drives the LP compressor. In addition to driving the LP compressor, the LP shaft can drive the fan through a power gearbox, which allows the fan to be rotated at fewer revolutions per unit of time than the rotational speed of the LP shaft for greater efficiency. The power gearbox typically includes a sun gear, one or more planet gears, and a ring gear. Lubrication fluid is provided to one or more of these gears and associated bearings during operation to cool down the gearbox, to increase its efficiency and to reduce wear. The lubrication fluid is typically collected within an inner casing of the gearbox and centrifuged out through openings defined between, e.g., a triple or quadruple flange assembly (i.e., a bolted joint) axially aligned with and positioned radially outward of the ring gear of the gearbox.

However, such a configuration may result in a relatively large radial footprint being required to collect the lubrication fluid, with consequent higher weight. Additionally, such a configuration requires precise engineering in the design of the bolted joint to avoid fretting at each discontinuous mating surface of the several coupled components. Accordingly, an improved configuration for collecting lubrication fluid within a gearbox of a gas turbine engine would be useful.

BRIEF DESCRIPTION

In one exemplary embodiment of the present disclosure, an epicyclic gearbox assembly for a gas turbine engine is provided. The epicyclic gearbox assembly defines an axial direction, a radial direction, a circumferential direction, a forward end, and an aft end. The epicyclic gearbox assembly includes a sun gear assembly; a planet gear assembly engaged with the sun gear assembly; and a ring gear assembly including one or more ring gears engaged with the planet gear assembly. The epicyclic gearbox assembly further includes a lubrication fluid collection assembly including a rotating oil scoop extending in the circumferential direction around the ring gear assembly, the rotating oil scoop coupled to the ring gear assembly at a location forward of one or more ring gears of the ring gear assembly.

In certain exemplary embodiments the ring gear assembly further includes a ring gear shaft, wherein the rotating oil scoop is coupled to the ring gear shaft at a location forward of the one or more ring gears.

For example, in certain exemplary embodiments the rotating oil scoop extends from a location forward of the one or more ring gears to a location aft of the one or more ring gears.

For example, in certain exemplary embodiments the rotating oil scoop is coupled to the ring gear shaft at a joint, wherein the ring gear shaft defines a plurality of lubrication fluid openings spaced along the circumferential direction and positioned aft of the joint along the axial direction.

The epicyclic gearbox assembly of claim4, wherein the plurality of lubrication fluid openings defined by the ring gear shaft are positioned forward of the one or more ring gears along the axial direction.

For example, in certain exemplary embodiments the rotating oil scoop is supported substantially completely at the joint.

In certain exemplary embodiments the lubrication fluid collection assembly further includes a static oil collector positioned at least partially outward of the rotating oil scoop along the radial direction.

For example, in certain exemplary embodiments the rotating oil scoop defines a plurality of lubrication fluid exits spaced along the circumferential direction, wherein the static oil collector defines an inlet, and wherein the inlet of the static oil collector is positioned outward of at least one of the lubrication fluid exits of the rotating oil scoop along the radial direction and aligned with at least one of the lubrication fluid exits of the rotating oil scoop along the axial direction.

For example, in certain exemplary embodiments the inlet of the static oil collector is a substantially continuous inlet along the circumferential direction.

For example, in certain exemplary embodiments the static oil collector defines an inlet for receiving lubrication fluid from the rotating oil scoop and a collection chamber for receiving lubrication fluid from the inlet, wherein the collection chamber extends substantially continuously along the circumferential direction.

For example, in certain exemplary embodiments the static oil collector includes an exit tube fluidly connected to the collection chamber.

For example, in certain exemplary embodiments the epicyclic gearbox assembly may further include a planet gear carrier, wherein the planet gear assembly is coupled to the planet gear carrier, and wherein the static oil collector is also coupled to the planet gear carrier.

For example, in certain exemplary embodiments the static oil collector is supported substantially completely by the planet gear carrier.

For example, in certain exemplary embodiments the static oil collector defines an overall length along the axial direction and a local height along the radial direction, wherein the overall length of the static oil collector is greater than the local height of the static oil collector.

In certain exemplary embodiments the planet gear assembly includes one or more planet gears, and wherein the epicyclic gearbox assembly further includes a forward lubrication fluid shroud positioned forward of the one or more planet gears of the planet gear assembly for containing lubrication fluid; and an aft lubrication fluid shroud positioned aft of the one or more planet gears of the planet gear assembly for containing lubrication fluid.

For example, in certain exemplary embodiments the forward lubrication fluid shroud defines an inside surface facing the one or more planet gears, wherein the aft lubrication fluid shroud defines an inside surface facing the one or more planet gears, wherein the rotating oil scoop extends from a location forward of the inside surface of the forward lubrication fluid shroud to a location aft of the inside surface of the aft lubrication fluid shroud.

In certain exemplary embodiments the rotating oil scoop extends substantially continuously from a forward end to an aft end.

In another exemplary embodiment of the present disclosure, a gas turbine engine is provided defining an axial direction, a radial direction, and a circumferential direction. The gas turbine engine includes a turbine section including a turbine; a fan assembly including a fan; and an epicyclic gearbox assembly coupling the turbine of the turbine section to the fan of the fan assembly. The epicyclic gearbox defines a forward end and an aft end and includes a sun gear assembly; a planet gear assembly engaged with the sun gear assembly; and a ring gear assembly including one or more ring gears engaged with the planet gear assembly. The epicyclic gearbox assembly further includes a lubrication fluid collection assembly including a rotating oil scoop extending in the circumferential direction around the ring gear assembly, the rotating oil scoop coupled to the ring gear assembly at a location forward of one or more ring gears of the ring gear assembly.

In certain exemplary embodiments the ring gear assembly further includes a ring gear shaft, wherein the rotating oil scoop is coupled to the ring gear shaft at a location forward of the one or more ring gears.

For example, in certain exemplary embodiments the rotating oil scoop is coupled to the ring gear shaft at a joint, wherein the ring gear shaft defines a plurality of lubrication fluid openings spaced along the circumferential direction and positioned aft of the joint along the axial direction, and wherein the rotating oil scoop is supported substantially completely at the joint.

DETAILED DESCRIPTION

The terms “forward” and “aft” refer to relative positions within a gas turbine engine or a component of a gas turbine engine, and refer to the normal operational attitude of the gas turbine engine or component. For example, with regard to a gas turbine engine, forward refers to a position closer to an engine inlet and aft refers to a position closer to an engine nozzle or exhaust.

Referring now to the drawings, wherein identical numerals indicate the same elements throughout the drawings,FIG. 1is a schematic cross-sectional view of a gas turbine engine in accordance with an exemplary embodiment of the present disclosure. More particularly, for the embodiment ofFIG. 1, the gas turbine engine is a high-bypass turbofan jet engine10, referred to herein as “turbofan engine10.” As shown inFIG. 1, the turbofan engine10defines an axial direction A (extending parallel to a longitudinal centerline12provided for reference) and a radial direction R that is normal to the axial direction A. In general, the turbofan engine10includes a fan section14and a core turbine engine16disposed downstream from the fan section14.

The exemplary core turbine engine16depicted generally includes a substantially tubular outer casing18that defines an annular inlet20. As schematically shown inFIG. 1, the outer casing18encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor22followed downstream by a high pressure (HP) compressor24; a combustion section26; a turbine section including a high pressure (HP) turbine28followed downstream by a low pressure (LP) turbine30; and a jet exhaust nozzle section32. A high pressure (HP) shaft or spool34drivingly connects the HP turbine28to the HP compressor24to rotate them in unison. A low pressure (LP) shaft or spool36drivingly connects the LP turbine30to the LP compressor22to rotate them in unison. The compressor section, combustion section26, turbine section, and nozzle section32together define a core air flowpath.

For the embodiment depicted inFIG. 1, the fan section14includes a variable pitch fan38having a plurality of fan blades40coupled to a disk42in a spaced apart manner. As depicted inFIG. 1, the fan blades40extend outwardly from the disk42generally along the radial direction R. Each fan blade40is rotatable relative to the disk42about a pitch axis P by virtue of the fan blades40being operatively coupled to a suitable actuation member44configured to collectively vary the pitch of the fan blades40in unison. The fan blades40, disk42, and actuation member44are together rotatable about the longitudinal axis12via a fan shaft45that is powered by the LP shaft36across a power gear box46. The power gear box46includes a plurality of gears for adjusting the rotational speed of the fan shaft45and thus the fan38relative to the LP shaft36to a more efficient rotational fan speed.

During operation of the turbofan engine10, a volume of air58enters the turbofan engine10through an associated inlet60of the nacelle50and/or fan section14. As the volume of air58passes across the fan blades40, a first portion of the air58as indicated by arrow62is directed or routed into the bypass airflow passage56, and a second portion of the air58as indicated by arrow64is directed or routed into the upstream section of the core air flowpath, or more specifically into the inlet20of the LP compressor22. The ratio between the first portion of air62and the second portion of air64is commonly known as a bypass ratio. The pressure of the second portion of air64is then increased as it is routed through the high pressure (HP) compressor24and into the combustion section26, where the highly pressurized air is mixed with fuel and burned to provide combustion gases66.

The combustion gases66are routed into and expand through the HP turbine28where a portion of thermal and/or kinetic energy from the combustion gases66is extracted via sequential stages of HP turbine stator vanes68that are coupled to the outer casing18and HP turbine rotor blades70that are coupled to the HP shaft or spool34, thus causing the HP shaft or spool34to rotate, thereby supporting operation of the HP compressor24. The combustion gases66are then routed into and expand through the LP turbine30where a second portion of thermal and kinetic energy is extracted from the combustion gases66via sequential stages of LP turbine stator vanes72that are coupled to the outer casing18and LP turbine rotor blades74that are coupled to the LP shaft or spool36, thus causing the LP shaft or spool36to rotate, thereby supporting operation of the LP compressor22and rotation of the fan38via the power gearbox46.

It should be appreciated, however, that the exemplary turbofan engine10depicted inFIG. 1is by way of example only, and that in other exemplary embodiments, the turbofan engine10may have any other suitable configuration. For example, in other exemplary embodiments, the fan38may be configured in any other suitable manner (e.g., as a fixed pitch fan) and further may be supported using any other suitable fan frame configuration. Moreover, it also should be appreciated that in other exemplary embodiments, any other suitable number or configuration of compressors, turbines, shafts, or a combination thereof may be provided. It also should be appreciated, that in still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine. For example, in other exemplary embodiments, aspects of the present disclosure may be incorporated into, e.g., a turboshaft engine, turboprop engine, turbocore engine, turbojet engine, etc.

Referring now toFIG. 2, a close-up, cross-sectional view is provided of an epicyclic gearbox assembly100in accordance with an exemplary embodiment of the present disclosure. The epicyclic gearbox assembly100generally defines an axial direction A, a radial direction R, and a circumferential direction C (seeFIG. 4), as well as a forward side102and an aft side104. In at least certain exemplary embodiments, the power gearbox46described above with reference toFIG. 1may be configured in substantially the same manner as the exemplary epicyclic gearbox assembly100depicted inFIG. 2, and described below. Accordingly, in such an exemplary embodiment, the axial, radial, and circumferential directions A, R, C of the epicyclic gearbox assembly100may correspond with an axial direction A, radial direction R, and circumferential direction of the gas turbine engine within which it is installed (see, e.g.,FIG. 1).

As is depicted, the epicyclic gearbox assembly100generally includes a sun gear assembly106, a planet gear assembly108, and a ring gear assembly110. The sun gear assembly106generally includes a forward sun gear112and an aft sun gear114spaced along the axial direction A. The forward sun gear112is coupled to a forward sun gear shaft116and the aft sun gear114is similarly coupled to and aft sun gear shaft118. The forward sun gear shaft116and aft sun gear shaft118are together coupled to an input shaft120, which may be, e.g., a low pressure shaft (e.g., LP shaft36, seeFIG. 1) of the gas turbine engine including the epicyclic gearbox assembly100.

The planet gear assembly108similarly includes a forward planet gear122and an aft planet gear124spaced along the axial direction A. The forward planet gear122and aft planet gear124are each engaged with the sun gear assembly106. More specifically, for the embodiment depicted, the forward planet gear122is engaged with the forward sun gear112and the aft planet gear124is engaged with the aft sun gear114. Notably, as will be appreciated, the forward planet gear122labeled inFIG. 2is a first forward planet gear122of a plurality of forward planet gears122and the aft planet gear124labeled inFIG. 2is a first aft planet gear124of a plurality of aft planet gears124. (More particularly, as will be depicted in, e.g.,FIG. 4, described below, for the embodiment shown, the plurality of forward planet gears122includes five forward planet gears122, and as will be appreciated, the plurality of aft planet gears124includes five aft planet gears124. However, in other embodiments, the plurality of forward planet gears122and plurality of aft planet gears124may instead have any other suitable number of planet gears.)

Further, it will be appreciated, that as used herein, the term “engaged,” with respect to two or more gears, refers to, e.g., one or more teeth of such gears engaging with one another such that the two gears rotate with each other. Accordingly, although one or more gears may be represented schematically in the Figs. as smooth circles for clarity, it will be appreciated that such gears actually include a plurality of teeth arranged along their circumference for engaging with an adjacent gear(s).

Referring still toFIG. 2, the ring gear assembly110includes one or more ring gears. However, in contrast to the sun gear assembly106and planet gear assembly108, the one or more ring gears of the ring gear assembly110is a single ring gear126. The ring gear126is engaged with the planet gear assembly108, and more specifically, is engaged with both the forward planet gear122and the aft planet gear124. The ring gear126is coupled to a ring gear shaft127. The ring gear shaft127is, in turn, coupled to an output shaft, which may be, e.g., a fan shaft of the gas turbine engine including the epicyclic gearbox assembly100(e.g., fan shaft45; seeFIG. 1).

Accordingly, given the separate forward and aft planet gears122,124and forward and aft sun gears112,114, the epicyclic gearbox assembly100may generally be referred to as a “split gear” epicyclic gearbox. It will be appreciated, however, that in other embodiments, the sun gear assembly106may instead include, e.g., a single sun gear, and/or the one or more ring gears of the ring gear assembly110may include separate forward and aft ring gears.

As will be appreciated, and as will be shown more clearly below with reference toFIG. 4, the epicyclic gearbox assembly100further includes a planet gear carrier128. The planet gear assembly108is coupled to the planet gear carrier128, and more specifically, each of the planet gears122,124of the planet gear assembly108are rotatably coupled to the planet gear carrier128. Accordingly, the planet gear carrier128allows each of the planet gears122,124of the planet gear assembly108to rotate about its respective local axis130, while maintaining the planet gears122,124stationary in the circumferential direction C of the epicyclic gearbox assembly100. Accordingly, it will be appreciated that the gearbox100may be referred to as a star gearbox. However, in other embodiments, one of the ring gear assembly110or sun gear assembly106may instead be held stationary, such that the gearbox100is instead configured as/referred to as a planetary gearbox or a differential gearbox, respectively.

Referring still toFIG. 2, in order to allow for the above configuration, the epicyclic gearbox assembly100further includes bearings. For example, in the embodiment shown, the epicyclic gearbox assembly100includes a forward bearing132for the forward planet gear122and an aft bearing134for the aft planet gear124. The forward bearing132generally includes an inner race136containing a plurality of rollers138. The plurality of rollers138of the forward bearing132are configured to interface between the forward planet gear122and the inner race136, allowing for relative rotational movement therebetween (i.e., about the local axis130). Similarly, the aft bearing134includes an inner race140containing a plurality of rollers142. The plurality of rollers142of the aft bearing134are configured to interface between the aft planet gear124and the inner race140, similarly allowing for relative rotational movement therebetween (i.e., about the local axis130). The inner races136,140of the forward bearing132and aft bearing134, respectively, are positioned on a planet gear member144(or planet pin) of the planet gear carrier128, and more specifically, are press fitted on the planet gear member144and retained along the axial direction A through a clamp assembly146. The clamp assembly146generally includes a forward clamp148and an aft clamp150coupled together using a tie bolt152.

In such a manner, the forward planet gear122and aft planet gear124may rotate relative to the planet gear carrier128about their local axes130, while maintaining a stationary position about the circumferential direction C of the epicyclic gearbox assembly100. (It should be appreciated, however, as stated above, the gearbox100may instead be configured as a planetary or differential gearbox, in which the planet gears122,124may rotate about the circumferential direction C of the epicyclic gearbox assembly100.)

It will further be appreciated that, although not depicted, the epicyclic gearbox assembly100further includes a lubrication system for providing lubrication fluid to various components of the epicyclic gearbox assembly100. For example, the lubrication system is configured to provide lubrication fluid to at least the bearings132,134and planet gears122,124of the planet gear assembly108. In addition, the exemplary epicyclic gearbox assembly100additionally includes features for containing the lubrication fluid provided to certain of these components by the lubrication system during operation of the epicyclic gearbox assembly100.

For example, for the embodiment depicted, the epicyclic gearbox assembly100further includes first, forward lubrication fluid shroud and a second, aft lubrication fluid shroud. The forward and aft lubrication fluid shrouds are configured to contain the lubrication motion within, or around, the planet gear assembly108and bearings132,134along the axial direction A. Accordingly, the forward lubrication fluid shroud is referred to herein as a forward axial shroud154and the aft lubrication fluid shroud is referred to herein as an aft axial shroud156. The forward axial shroud154is positioned forward of the one or more planet gears of the planet gear assembly108(including the forward planet gear122) along the axial direction A, and the aft axial shroud156is positioned aft of the one or more planet gears of the planet gear assembly108(including the aft planet gear124) along the axial direction A.

Further, it will be appreciated that the forward axial shroud154defines an inside surface158(seeFIG. 3) facing the one or more planet gears of the planet gear assembly108(including the forward planet gear122) and, similarly, the aft axial shroud156includes an inside surface160facing the one or more planet gears of the planet gear assembly108(including the aft planet gear124). More specifically, the forward axial shroud154covers substantially all of a forward side of the forward planet gear122and the aft axial shroud156covers substantially all of an aft side of the aft planet gear124. Further, the forward axial shroud154covers substantially all of the forward bearing132and the aft axial shroud156covers substantially all of the aft bearing134. As used herein, the term “covers” with reference to the forward and aft axial shrouds154,156refers to the component overlapping the other component when viewed along the axial direction A of the epicyclic gearbox assembly100.

In certain embodiments, the aft axial shroud156may be configured in substantially the same manner as the forward axial shroud154(with, e.g., some minor distinctions allowing for ease of installation). Additionally, it will be appreciated that for the embodiments shown, the portions of forward axial shroud154and aft axial shroud156covering the forward planet gear122and aft planet gear124, respectively, as well as the forward bearing132and aft bearing134, respectively, extend substantially along the radial direction of the epicyclic gearbox assembly100.

It will further be appreciated that the forward axial shroud154is positioned relatively close to the forward side of the forward planet gear122and the aft axial shroud156is positioned relatively close to the aft side of the aft planet gear124. More specifically, for the embodiment shown the forward axial shroud154defines an axial separation162from the forward planet gear122(i.e., a minimum separation between the two components along the axial direction A) that is less than about 0.5 inches, and the aft axial shroud156defines an axial separation164from the aft planet gear124also less than about 0.5 inches. Notably, however, in other embodiments, the axial separations162,164may instead be, e.g., less than about 0.7 inches, such as less than about 0.4 inches, such as less than about 0.3 inches, such as less than about 0.25 inches.

Inclusion of the forward axial shroud154and aft axial shroud156may assist with containing the lubrication fluid motion along the axial direction A of the epicyclic gearbox assembly100, such that the lubrication fluid provided to, e.g., the bearings134,136and/or the planet gears122,124during operation generates lower windage losses and is maintained/contained close to the contacting surfaces of such components for a longer period of time, increasing an efficiency and lifespan of the epicyclic gearbox assembly100, especially in the case of an inadvertent oil flow interruption, e.g. in a “negative g” flight phase. In addition, inclusion of the forward axial shroud154and aft axial shroud156may also assist with directing the lubrication fluid in a desired manner for collection.

Accordingly, it will further be appreciated that the epicyclic gearbox assembly100also includes features for efficiently collecting lubrication fluid previously provided to the various components of the epicyclic gearbox assembly100, as described above. More specifically, referring now toFIG. 3, providing a close-up view of a portion of the exemplary gearbox assembly100ofFIG. 2, it will be appreciated that the epicyclic gearbox assembly100further includes a lubrication fluid collection assembly170. The lubrication fluid collection assembly170generally includes a rotating oil scoop172and a static oil collector174. The rotating oil scoop172extends in the circumferential direction C around the ring gear assembly110(see alsoFIG. 4) and the static oil collector174is positioned at least partially outward of the rotating oil scoop172along the radial direction R.

As is depicted, the rotating oil scoop172is coupled to the ring gear assembly110at a location forward of the one or more ring gears of the ring gear assembly110, or rather, forward of each of the one or more ring gears of the ring gear assembly110(which, for the embodiment depicted, is the single ring gear126). More specifically, the rotating oil scoop172is coupled to the ring gear shaft127of the ring gear assembly110at a location forward of the ring gear126, and more specifically still, at a joint176. The rotating oil scoop172is supported substantially completely at the joint176. It will accordingly be appreciated that the rotating oil scoop172is fixed to, and configured to rotate with the ring gear assembly110(hence a “rotating” oil scoop).

By contrast, the static oil collector174is coupled to the planet gear carrier128. More specifically, the static oil collector174includes a flange178at an aft end of the static oil collector174bolted to the planet gear carrier128. In such a manner, the static oil collector174is supported substantially completely by the planet gear carrier128, and more specifically is supported substantially completely at the flange178by the planet gear carrier128. Notably, the flange178is positioned aft of the one or more ring gears (i.e., the ring gear126) of the ring gear assembly110. It will accordingly be appreciated that the static oil collector174is fixed to a stationary component of the epicyclic gearbox assembly100, and therefore is not configured to rotate about the axial direction A (hence a “static” oil collector).

Further, the rotating oil scoop172generally includes a forward end180coupled to the ring gear shaft127at the joint176and an aft end182. As is depicted, for the embodiment shown the forward end180of the rotating oil scoop172and the joint176are each positioned forward of the ring gear126and the aft end182of the rotating oil scoop172is positioned aft of the ring gear126. Accordingly, it will be appreciated that the rotating oil scoop172extends from a location forward of the ring gear126to a location aft of the ring gear126. More specifically, for the embodiment depicted, the rotating oil scoop172extend substantially continuously from the forward end180positioned forward of the ring gear126to the aft end182positioned aft of the ring gear126(e.g., with no flanges or joints positioned therebetween). More specifically, still, for the embodiment depicted the rotating oil scoop172extends from a location forward of the inside surface158of the forward axial shroud154to a location aft of the inside surface160of the aft axial shroud156.

Moreover, referring still toFIG. 3the ring gear shaft127defines a plurality of lubrication fluid openings184spaced along the circumferential direction C. The lubrication fluid openings184are positioned forward of the ring gear126along the axial direction A and aft of the joint176along the axial direction A. However, in other embodiments, the plurality of lubrication fluid openings184may be positioned elsewhere or configured in any other suitable manner.

Accordingly, it will be appreciated that during operation of the epicyclic gearbox assembly100, lubrication fluid may flow (as is indicated by arrows186) from a location forward of the ring gear126(e.g., from between the plurality of planet gears122,124and the forward axial shroud154) and through the plurality of openings184in the ring gear shaft127to be collected by the rotating oil scoop172. Additionally, during operation of the epicyclic gearbox assembly100, lubrication fluid186may also flow from a location aft of the ring gear126(e.g., from between the plurality of planet gears122,124and the aft axial shroud156) and may be collected by the aft end182of the rotating oil scoop172. Notably, the aft end182of the rotating oil scoop172includes a lip188to assist with the collection of such lubrication fluid (the lip188extending generally inwardly along the radial direction R).

Moreover, the rotating oil scoop172further includes a radially outer-most portion190. The lubrication fluid collection assembly170is configured to transfer lubrication fluid collected by the rotating oil scoop172in the radially outer-most portion190of the rotating oil scoop172to the static oil collector174. More specifically, the rotating oil scoop172defines a plurality of lubrication fluid exits192spaced along the circumferential direction C at the radially outer-most portion190. Each of the plurality of lubrication fluid exits192defined by the rotating oil scoop172is configured as an opening allowing for a flow of lubrication oil therethrough (again represented by arrows186).

Briefly, it should be appreciated that during operation of the planet gear assembly100, the lubrication fluid may be centrifuged outwardly along the radial direction R due to, e.g., a relatively high rotational speed of at least certain components within the epicyclic gearbox assembly100. Accordingly, in such a manner the lubrication fluid may have a relatively high amount of kinetic energy as it begins to be centrifuged radially outwardly during operation of the epicyclic gearbox assembly100.

Referring still toFIG. 3, the static oil collector174, which is located at least partially outward of the rotating oil scoop172along the radial direction R, defines an inlet194. The inlet194of the static oil collector174is positioned outward of at least one of the lubrication fluid exits192of the rotating oil scoop172along the radial direction R and aligned with at least one of the lubrication fluid exits192of the rotating oil scoop172along the axial direction A. Furthermore, the lubrication fluid collection assembly170includes a forward seal196positioned forward of the lubrication fluid exits192of the rotating oil scoop172and inlet194of the static oil collector174, as well as an aft seal198positioned aft of the lubrication fluid exits192of the rotating oil scoop172and inlet194of the static oil collector174. In such a manner, lubrication fluid may be transferred from the rotating oil scoop172to the static oil collector174by transferring such lubrication fluid from the plurality of exits192to the inlet194.

Referring now also toFIG. 4, it will be appreciated that the static oil collector174further defines a collection chamber200for receiving lubrication fluid from the inlet194.FIG. 4provides a schematic, forward end view of the plant gearbox assembly ofFIGS. 2 and 3. Notably, the ring gear assembly110and rotating oil scoop172of the lubrication fluid collection assembly170is removed fromFIG. 4for clarity.

As is depicted, the inlet194of the static oil collector174is configured as a substantially continuous inlet194extending along the circumferential direction C. Notably, however, in other embodiments, the static oil collector174may instead define a plurality of inlets194spaced along the circumferential direction C, with each of these inlets194being fluidly connected to the collection chamber200. For example, with such an embodiment, each of the plurality of inlets194may be aligned with at least one lubrication fluid exit192along the axial direction A and be positioned radially outward of at least one lubrication fluid exit192along the radial direction R. (Of course, however, during operation of the epicyclic gearbox assembly100, the rotating oil scoop172will be rotating relative to the stationary oil collector174, and accordingly, the individual exit192which a given inlet194is positioned radially outward of will continuously change.)

As with the embodiment shown including the single inlet194extending substantially continuously along the circumferential direction C, the collection chamber200also extends substantially continuously along the circumferential direction C. Additionally, the static oil collector174includes an exit tube202fluidly connected to the collection chamber200. In such a manner, during operation of the epicyclic gearbox assembly100, lubrication fluid may flow (as indicated by arrows186) from the plurality of lubrication fluid exits192defined by the rotating oil scoop172, through the inlet194of the static oil collector174, and into the collection chamber200of the static oil collector174(see particularly,FIG. 3). More specifically, as is first shown inFIG. 3, the flow of lubrication fluid186into the collection chamber200may swirl around the collection chamber200, losing a small amount of kinematic energy while preventing the generation of turbulence in the fluid, hence reducing the risk of foaming of the lubrication fluid. Further, as is shown inFIG. 4, the flow of lubrication fluid186within the collection chamber200may swirl through the collection chamber200in the circumferential direction C, further losing a relatively small amount of kinetic energy within the flow of lubrication fluid186and reducing the risk of foaming of the lubrication fluid. The collected lubrication fluid within the collection chamber200may then exit through the exit tube202of the static oil collector174, which as is shown is fluidly connected to the collection chamber200. The exit tube202may be fluidly connected to a lubrication fluid sump (not shown) to receive such lubrication fluid, re-pressurize the lubrication fluid, and provide the lubrication fluid back through the lubrication system of the epicyclic gearbox assembly100.

Notably, by relatively gradually reducing the amount of kinetic energy within the flow of lubrication fluid in the manner described herein, the lubrication fluid may more efficiently be collected and directed to a scavenge port during normal flight phases, as well as during, e.g., “negative g” flight phases. In addition, relatively gradually reducing the amount of kinetic energy within the flow of lubrication fluid may reduce the risk of foaming of the lubrication fluid dramatically (e.g., close to zero).

Moreover, it will be appreciated that the lubrication fluid collection assembly170configured in accordance with one or more the embodiments described herein may result in a lubrication fluid collection assembly170able to be packaged in a smaller radial envelope. For example, with reference back particularly toFIG. 3the static oil collector174defines an overall length204along the axial direction A and a local height206along the radial direction R. The overall length204of the static oil collector174is greater than the local height206of the static oil collector174. Further, by coupling the rotating oil scoop172to the ring gear assembly110at a location forward of the one or more ring gears126, the rotating oil scoop172may also have a relatively small radial footprint, as no flanges or other attachment means are required at a location axially aligned with, and positioned radially outward of, the ring gear126.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment.

While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.