Patent ID: 12258904

DETAILED DESCRIPTION

Features, advantages, and embodiments of the present disclosure are set forth or apparent from a consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that the following detailed description is exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed.

Various embodiments are discussed in detail below. While specific embodiments are discussed, this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and the scope of the present disclosure.

As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.

The terms “coupled,” “fixed,” “attached,” “connected,” and the like, refer to both direct coupling, fixing, attaching, or connecting, as well as indirect coupling, fixing, attaching, or connecting through one or more intermediate components or features, unless otherwise specified herein.

The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” “generally,” and “substantially” is not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or the machines for constructing the components and/or the systems or manufacturing the components and/or the systems. For example, the approximating language may refer to being within a one, a two, a four, a ten, a fifteen, or a twenty percent margin in either individual values, range(s) of values and/or endpoints defining range(s) of values.

As used herein, “passively pressurize” is pressurizing a component with potential energy (e.g., mechanical energy or air pressure), and without the use of dedicated control systems or pumps.

As used herein, “passive auxiliary lubrication” includes supplying lubrication using potential energy (e.g., a pressure differential within the system) and without the use of dedicated control systems or pumps.

The present disclosure provides for a passive auxiliary lubrication system for providing lubricant (e.g., oil) to a gearbox assembly of an engine, such as a gas turbine engine. The engine includes a primary lubrication system and the passive auxiliary lubrication system for providing the lubricant to the gearbox assembly. The primary lubrication system includes a pump that pumps lubricant from a primary tank to the gearbox assembly for lubricating components of the gearbox assembly (e.g., gears, gear meshes, journal bearings, or the like). The pump pressurizes the lubricant from the primary tank such that pressurized lubricant is provided to the gearbox assembly. In some instances, the pressure of the lubricant in the primary lubrication system may decrease such that the primary lubrication system is unable to provide the lubricant to the gearbox assembly. For example, an abnormal event may cause the pump to be non-operational. In such instances, the passive auxiliary lubrication system passively provides lubricant to the gearbox assembly. The passive auxiliary lubrication system includes an auxiliary tank, a tank recharge line, and an auxiliary lubricant discharge line. In some examples, the auxiliary tank includes a spring-loaded piston to passively pressurize the lubricant in the auxiliary tank. In some examples, the auxiliary tank receives bleed air from a compressor of the engine to passively pressurize the lubricant. In some examples, the auxiliary tank also includes a mechanical stop to stop the piston such that the piston may not move beyond the mechanical stop.

In operation, the lubricant is directed from the primary lubrication system to fill the auxiliary tank. For example, the lubricant is pumped from the primary tank and flows into the auxiliary tank. A check valve in the recharge line opens to allow the lubricant to flow into the auxiliary tank until the auxiliary tank reaches a predetermined pressure. The auxiliary tank is passively pressurized (e.g., mechanically energized) via the internal spring-loaded piston. In some examples, the auxiliary tank is passively pressurized by the bleed air from the compressor. When the primary lubrication system loses pressure, the passively pressurized lubricant is supplied to the gearbox assembly. For example, the piston pushes the lubricant out of the auxiliary tank and into the auxiliary lubricant discharge line. When the pressure in the primary lubrication system decreases below a predetermined threshold, a check valve in the auxiliary lubricant discharge line opens to allow the lubricant to flow from the auxiliary tank to the gearbox assembly. In this way, the lubricant in the auxiliary tank bypasses the pump of the primary lubrication system. Thus, the passive auxiliary lubrication system supplies lubricant to the gearbox assembly without the use of a pump. For example, the spring-loaded piston pushes the lubricant out of the auxiliary tank and to the gearbox assembly. In some examples, the check valve in the auxiliary lubricant discharge line may include an actuated valve controlled by a controller.

The lubricant from the auxiliary tank is supplied directly to the planet gear support pins of the gearbox assembly. The lubricant is then routed to the other components, such as the journal bearings and the gear meshes. For example, the lubricant may be routed to the journal bearings and the gear interfaces via ports running axially through the pins and radially to the journal bearings and the gear interfaces. When the planet carrier is a rotating planet carrier (e.g., the ring gear rotates), this aspect provides a way to transfer the lubricant across either axial gaps or radial gaps between the stationary component (e.g., the auxiliary lubricant discharge line) and the rotating component (e.g., the rotating planet carrier).

Referring now to the drawings,FIG.1illustrates a schematic cross-sectional view of a gas turbine engine, also referred to as engine10. As shown inFIG.1, the engine10is depicted as a high bypass turbofan engine, incorporating an exemplary embodiment of a shaft assembly95according to an aspect of the present disclosure. Although further described below with reference to a turbofan engine, the present disclosure is also applicable to wind turbines and turbomachinery in general, including turbofan, propfan, turbojet, and turboshaft gas turbine engines, including marine and industrial turbine engines and auxiliary power units. As shown inFIG.1, the engine10has an axial centerline axis, also referred to as axis12, that extends therethrough for reference purposes. The engine10defines an axial direction A and a radial direction R. The engine10includes a forward end98and an aft end99along the axial direction A.

In general, the engine10includes an engine core20and a fan14. The engine core20generally includes, in serial flow arrangement, a compressor section21, a combustion section26, and a turbine section31. The compressor section21defines one or more compressors, such as a high-pressure compressor (HPC)24and a low-pressure compressor (LPC)22. The turbine section31defines one or more turbines, such as a high-pressure turbine (HPT)28and a low-pressure turbine (LPT)30. In various embodiments, the compressor section21may further include an intermediate pressure compressor (IPC). In still other embodiments, the turbine section31may further include an intermediate pressure turbine (IPT). In wind turbine applications, the engine core20may generally be defined as one or more generators.

The LPC22, the HPC24, the HPT28, and the LPT30each includes one or more rotors32. In one embodiment, the one or more rotors32includes one or more shafts35of the engine10connecting the compressor section21to the turbine section31. In other embodiments, the one or more rotors32generally defines a disk33extended in the radial direction R and a plurality of airfoils36connected in a circumferentially adjacent arrangement and extending outward in the radial direction R from the disk33. In various embodiments, one or more compressors of the compressor section21are coupled to and are rotatable with one or more turbines of the turbine section31by way of the one or more shafts35.

The fan14generally includes a fan rotor15. The fan rotor15includes a plurality of fan blades42that are coupled to and extend outwardly from the fan rotor15in the radial direction R. In the embodiments shown inFIG.1, the fan rotor15extends in the axial direction A toward the forward end98from a gearbox assembly40. The gearbox assembly40may include a reduction gearbox. The fan14further includes the shaft assembly95coupled to the gearbox assembly40, extended toward the aft end99and coupled to the engine core20.

In one embodiment, the gearbox assembly40includes a gear train assembly50having any suitable configuration, such as a planetary configuration or a star configuration. For example, as shown in the illustrated embodiment, the gear train assembly50includes a sun gear52and a plurality of planet gears54. In some examples the plurality of planet gears54are each fixed such that each planet gear54rotates on a fixed axis relative to the sun gear52. A ring gear56surrounds the plurality of planet gears54and rotates and transfers power and torque from the sun gear52through the plurality of planet gears54. In some examples, the ring gear56is coupled to the fan rotor15. In some examples, the ring gear56is fixed and a planet carrier (not shown inFIG.1) is coupled to the fan rotor15such that the planet carrier rotates and transfers power and torque from the sun gear52through the plurality of planet gears54, as detailed further below. In one embodiment, the sun gear52is attached to, or integral with, the shaft assembly95. In various embodiments, the gearbox assembly40may further include additional planet gears disposed radially between the plurality of planet gears54and the sun gear52, or between the plurality of planet gears54and the ring gear56. A lubrication system200provides lubrication to various components of the gearbox assembly40, as detailed further below.

The shaft assembly95is coupled to the engine core20to transmit torque and power through the sun gear52to the gearbox assembly40and to the fan rotor15. The fan rotor15is connected to the surrounding ring gear56to receive torque from the sun gear52and to transfer torque to drive the fan14. Alternatively, the fan rotor15is connected to the planet gears54(e.g., via the planet carrier) to receive torque from the sun gear52and to transfer torque to drive the fan14. As power and torque are transmitted from the engine core20, the gearbox assembly40provides power and torque at an output speed to the fan rotor15more suitably adjusted for the fan14. For example, the gearbox assembly40may reduce the speed of the fan rotor15relative to the engine core20by a factor greater than one.

During operation of the engine10, as shown inFIG.1, a volume of air (as indicated by arrow90) enters the engine10. As the air passes across the fan blades42, a portion of the air (as indicated by arrow91) is directed outside of the engine core20to provide propulsion. Additionally, another portion of air (as indicated by arrow92) is directed through an associated inlet80into the compressor section21. The air (as indicated by arrow92) is progressively compressed as it flows through the compressor section21, such as through the LPC22and through the HPC24, toward the combustion section26.

The now compressed air (as indicated by arrow93) flows into the combustion section26where a fuel is introduced. The fuel is mixed with at least a portion of the compressed air, and the fuel-air mixture is ignited to form combustion gases (as indicated by the arrow94). The combustion gases flow into the turbine section31, causing rotary members of the turbine section31to rotate and to support operation of respectively coupled rotary members in the compressor section21and/or may rotate the fan14. For example, the HPC24and the HPT28is rotatable to drive the engine10and to generate the combustion gases at the combustion section26to drive the LPT30. In some examples, the LPT30is connected to the LPC22. Referring toFIG.1, a coupling shaft82is coupled to the LPC22at a first end84and to the gearbox assembly40at a second end86. In other embodiments, the coupling shaft82is coupled to the HPC24at the first end84. In other embodiments, the coupling shaft82is coupled to the turbine section31at the first end84and to the gearbox assembly40at the second end86. In other embodiments, the coupling shaft82is coupled to the HPT28at the first end84. The gearbox assembly40may reduce the rotational speed from the engine core20(e.g., the compressor section21or the turbine section31) and provide a desired amount of torque and a desired amount of rotational speed to the fan14.

FIG.2is a schematic side view of an exemplary lubrication system200ofFIG.1, according to aspects of the present disclosure. The lubrication system200includes a primary lubrication system202and a passive auxiliary lubrication system220. The primary lubrication system202includes a primary tank204, a pump206, and a primary supply line208. The primary tank204stores a fluid, such as a lubricant (e.g., oil). The pump206pressurizes the lubricant and pumps the pressurized lubricant from the primary tank204. The pressurized lubricant is supplied through the primary supply line208to the gearbox assembly40(as indicated by the arrow211) to lubricate various components of the gearbox assembly40, as detailed further below.

The passive auxiliary lubrication system220includes an auxiliary tank222, an auxiliary tank feed line224, an auxiliary supply line226, a first valve225, and a second valve227. The auxiliary tank222includes a passively pressurized reservoir for storing lubricant. For example, the auxiliary tank222may include a piston230. The piston230is attached to a spring232such that the piston230is spring-loaded. In this way, the piston230reciprocates (e.g., up and down) within the auxiliary tank222to pressurize the lubricant in the auxiliary tank222and to provide the lubricant in the auxiliary tank222to the gearbox assembly40, as detailed further below. The piston230may include ways other than a spring for enabling reciprocation of the piston230.

In some examples, the auxiliary tank222also includes a mechanical stop234. The mechanical stop234in the auxiliary tank222prevents the piston230from moving beyond the mechanical stop234. In this way, the mechanical stop234prevents the spring232from being over compressed. The mechanical stop234may be placed anywhere within the auxiliary tank222, as desired, for controlling an amount of spring compression of the spring232.

The auxiliary tank feed line224is fluidly coupled with the primary tank204of the primary lubrication system202and is fluidly coupled with the auxiliary tank222. The auxiliary supply line226is fluidly coupled with the auxiliary tank222and the gearbox assembly40, as detailed further below.

The first valve225is disposed in the auxiliary tank feed line224. In some examples, the first valve225includes a check valve. For example, the first valve225includes a one-way check valve that allows fluid (e.g., lubricant) to flow through the first valve225in only one direction. The first valve225includes a cracking pressure that is a minimum differential upstream pressure between an inlet of the first valve225and an outlet of the first valve225at which the first valve225will operate. For example, the first valve225allows lubricant to flow from the primary supply line208through the auxiliary tank feed line224towards the auxiliary tank222if a pressure of the lubricant at an upstream side of the first valve225is greater than a pressure of the lubricant at a downstream side of the first valve225. In this way, the first valve225is considered to be a passive valve. The first valve225may also include an actuated valve mechanically controlled by a controller (not shown), or may include a valve controlled by pressure feedback in the auxiliary tank feed line224.

The second valve227is disposed in the auxiliary supply line226. In some examples, the second valve227includes a check valve. For example, the second valve227includes a one-way check valve that allows fluid (e.g., lubricant) to flow through the second valve227in only one direction. The second valve227includes a cracking pressure that is a minimum differential upstream pressure between an inlet of the second valve227and an outlet of the second valve227at which the second valve227will operate. For example, the second valve227allows lubricant to flow from the auxiliary tank222through the auxiliary supply line226towards the gearbox assembly40if a pressure of the lubricant at an upstream side of the second valve227is greater than a pressure at a downstream side of the second valve227. In this way, the second valve227is considered to be a passive valve. The second valve227may also include an actuated valve mechanically controlled by a controller (now shown), or may include a valve controlled by pressure feedback in the auxiliary supply line226. For example, the controller receives signals from one or more pressure sensors and determines when the pressure in the primary lubrication system202is less than the pressure in the auxiliary tank222. In such instances, the controller opens the second valve227.

In operation, the auxiliary tank222is empty (or substantially empty) prior to startup of the engine10. In such instances, the piston230is at or adjacent an internal bottom side of the auxiliary tank222. When the engine10is started, the pump206begins to pump the lubricant from the primary tank204and pressurizes the lubricant. The pressurized lubricant flows through the auxiliary tank feed line224towards the auxiliary tank222(as indicated by arrow213). Since the auxiliary tank222is empty (or substantially empty), the pressurized lubricant passes through the first valve225(e.g., the pressurized lubricant includes a greater pressure than a pressure in the auxiliary tank222). The pressurized lubricant then fills the auxiliary tank222. In this way, the lubricant is supplied to the auxiliary tank222from the primary lubrication system202. As the pressurized lubricant flows into the auxiliary tank222, the pressurized lubricant causes the piston230to be reciprocated. In other words, the pressurized lubricant filling the auxiliary tank222causes the piston230to move in an upward direction. In this way, the spring232compresses and stores potential energy. When the spring232has fully compressed and/or when the piston230has been moved to the mechanical stop234, the auxiliary tank222is full with pressurized lubricant. In such a state, the auxiliary tank222is considered to be charged. Thus, the auxiliary tank222is mechanically pre-loaded or mechanically pressurized (e.g., pressurized without the use of a pump). The lubricant stored in the auxiliary tank222is also referred to as an auxiliary lubricant201.

When the auxiliary tank222is charged (e.g., the auxiliary tank222is full), the first valve225prevents additional pressurized lubricant from flowing to the auxiliary tank222. For example, the pressure in the auxiliary tank222is greater than or equal to the pressure of the pressurized lubricant upstream of the first valve225. The pump206then continuously pumps lubricant from the primary tank204and supplies the pressurized lubricant through the primary supply line208, and towards the gearbox assembly40to lubricate various components of the gearbox assembly40, as detailed further below.

In some instances, the primary lubrication system202may cease from operation or otherwise may not be available. For example, an abnormal operating event may cause the primary lubrication system202to lose pressure (e.g., due to a failure of the pump206, a shutdown of engine10, or another cause). In such instances, the primary lubrication system202is unable to provide pressurized lubricant to the gearbox assembly40or the primary lubrication system202is unable to provide adequate pressure of the lubricant for providing the lubricant to the gearbox assembly40(e.g., to the components of the gearbox assembly40). Thus, the passive auxiliary lubrication system220supplies the auxiliary lubricant201from the auxiliary tank222to the gearbox assembly40. For example, during such abnormal operating event, a pressure in the primary supply line208decreases (e.g., due to the pump206stopping) below a predetermined pressure threshold. The second valve227then opens. For example, the pressure in the auxiliary tank222is greater than the pressure in the primary supply line208of the primary lubrication system202. Thus, the auxiliary lubricant201is discharged from the auxiliary tank222and flows through the auxiliary supply line226, through the primary supply line208, and towards the gearbox assembly40(as indicated by arrow215) for lubricating various components of the gearbox assembly40, as detailed further below. In this way, the auxiliary lubricant201is supplied from the auxiliary tank222to the gearbox assembly40. The spring232extends or otherwise decompresses and the piston230pushes the auxiliary lubricant201out of the auxiliary tank222through the auxiliary supply line226. The auxiliary lubricant201flows out of the auxiliary tank222until the auxiliary tank222is empty or is substantially empty. Thus, the auxiliary tank222is no longer charged or pre-loaded.

When the abnormal operating event ends and/or when the engine10is powered back on, the auxiliary tank222is passively pressurized and is recharged, as detailed above. Thus, the passive auxiliary lubrication system220provides the auxiliary lubricant201to the gearbox assembly40without the use of additional components. For example, the passive auxiliary lubrication system220supplies the auxiliary lubricant201from the auxiliary tank222to the gearbox assembly40without a pump. In some examples, the passive auxiliary lubrication system220includes an isolation valve, or the like, for shutting off the supply of lubricant from the auxiliary tank222. For example, the isolation valve may shut off the supply of lubricant from the auxiliary tank222when the engine10is shutdown such that the lubricant does not flow from the auxiliary tank222to the gearbox assembly40when the engine10is not running.

FIG.3shows a schematic partial cross-sectional side view of another exemplary gearbox assembly340and a passive auxiliary lubrication system320(shown schematically inFIG.3). The gearbox assembly340may be employed in the engine10ofFIG.1. That is, the gearbox assembly340couples the one or more shafts35to the fan14(FIG.1). The passive auxiliary lubrication system320ofFIG.3includes many of the same or similar components and functionality as the embodiment shown inFIG.2. The same reference numeral is used for the same or similar components in these two embodiments, and a detailed description of these components and functionality is omitted here.

The gearbox assembly340includes a sun gear352, a plurality of planet gears354(only one of which is visible inFIG.3), and a ring gear356. For clarity, only a portion of the gears is shown. The gearbox assembly340is a star type or a rotating ring gear type gearbox assembly (e.g., the ring gear356is rotating and a planet carrier358is fixed and stationary). The planet carrier358constrains the plurality of planet gears354such that the plurality of planet gears354do not together rotate around the sun gear352while enabling each planet gear of the plurality of planet gears354to rotate about its own axis13. The ring gear356is coupled via the fan rotor15to the fan14(FIG.1) and rotates to drive rotation of the fan14(FIG.1) about the axis12. Radially inward of the ring gear356, and intermeshing therewith, is the plurality of planet gears354. Each of the planet gears of the plurality of planet gears354includes a pin350about which a respective planet gear rotates.

The gearbox assembly340includes one or more passages to supply the lubricant from the lubrication system200(FIG.2) to the various gears and components of the gearbox assembly340. The one or more passages include one or more first passages361and one or more second passages363. The one or more first passages361allow the lubricant to flow in an axial direction. For example, the one or more first passages361allow the lubricant to flow through the pin350. The one or more second passages363allow the lubricant to flow in a radial direction. For example, the one or more second passages363allow the lubricant to flow from the one or more first passages361to the various gears (e.g., the sun gear352, one or more of the plurality of planet gears354, and/or the ring gear356).

As shown inFIG.3, the passive auxiliary lubrication system320is in fluid communication with the gearbox assembly340. For example, the auxiliary supply line226is fluidly coupled to the pin350for supplying the auxiliary lubricant201from the auxiliary tank222through the pin350to the gears of the gearbox assembly340(e.g., through the one or more first passages361and the one or more second passages363), as detailed further below.

In the embodiment ofFIG.3, the passive auxiliary lubrication system320includes an auxiliary tank322. The auxiliary tank322is alternatively, or additionally, recharged using compressor bleed air. For example, the auxiliary tank322is in fluid communication with a compressor bleed air line370that fluidly couples the auxiliary tank322with the compressor section21(e.g., with the HPC24and/or the LPC22) (FIG.1). In this way, the auxiliary tank322receives the compressor bleed air via the compressor bleed air line370(as indicated by arrow317). The compressor bleed air enters the auxiliary tank322and pressurizes the auxiliary tank322. For example, the compressor bleed air fills a remaining portion of the auxiliary tank322that is not otherwise occupied by the auxiliary lubricant201. Thus, the auxiliary tank322is passively pressurized by the compressor bleed air. In some examples, the compressor bleed air line370includes a third valve372and a pressure regulator374. The third valve372includes a check valve or an actuated valve, similar to that of the first valve225and the second valve227(FIG.2). The pressure regulator374controls the pressure inside the auxiliary tank322in a manner to maintain a desired pressure or a required pressure or until the pressure inside the auxiliary tank322reaches a desired pressure or a require pressure. For example, the pressure regulator374monitors the pressure inside the auxiliary tank322and opens and/or closes the third valve372to regulate an amount of the compressor bleed air into the auxiliary tank322. The third valve372remains open to allow a flow of compressor bleed air into the auxiliary tank322until a desired pressure is reached. The third valve372then closes to prevent additional compressor bleed air from flowing into the auxiliary tank322. In this way, the auxiliary tank322is passively pressurized by the compressor bleed air to charge and/or to recharge the auxiliary tank322.

In operation, during an abnormal operating event in which the primary lubrication system202(FIG.2) is unavailable or is unable to provide lubrication to the gearbox assembly340, the passive auxiliary lubrication system320supplies the auxiliary lubricant201to the gearbox assembly340, as detailed above. The auxiliary lubricant201from the auxiliary tank322is fed to one or more of the gears, for example, to the sun gear352, to one or more of the plurality of planet gears354, to the ring gear356, or any combination thereof, via one or more of the one or more first passages361and/or via the one or more second passages363. For example, the auxiliary lubricant201flows into the pin350through a connection between the auxiliary supply line226and the one or more first passages361. In this way, the auxiliary supply line226is fluidly coupled to the one or more first passages361. The auxiliary lubricant201then flows through the one or more second passages363to the various gears to lubricate the gears (e.g., the sun gear352, one or more of the plurality of planet gears354, and/or the ring gear356). Thus, the passive auxiliary lubrication system320supplies auxiliary lubricant from the auxiliary tank322to the gearbox assembly340to lubricate the various gears of the gearbox assembly340(e.g., journal bearings, gear meshes, etc. of the various gears).

FIG.4shows a schematic partial cross-sectional side view of another exemplary gearbox assembly440and another exemplary passive auxiliary lubrication system420(shown schematically inFIG.4). The gearbox assembly440may be employed in the engine10ofFIG.1. That is, the gearbox assembly440couples the one or more shafts35to the fan14(FIG.1). The passive auxiliary lubrication system420ofFIG.4includes many of the same or similar components and functionality as the embodiments shown inFIGS.2and3. The same reference numeral is used for the same or similar components in these embodiments, and a detailed description of these components and functionality is omitted here.

The gearbox assembly440includes a sun gear452, a plurality of planet gears454(only one of which is visible inFIG.4), and a ring gear456. For clarity, only a portion of the gears is shown. The gearbox assembly440is of a fixed ring gear type (e.g., the ring gear456is stationary and fixed, while a planet carrier458and the plurality of planet gears454are rotating). The planet carrier458constrains the plurality of planet gears454to rotate around the sun gear452in synchronicity while enabling each planet gear of the plurality of planet gears454to rotate about its own axis13. The planet carrier458is coupled via the fan rotor15to the fan14(FIG.1) and rotates with the plurality of planet gears454in order to drive rotation of the fan14(FIG.1) about the axis12. Radially outwardly of the plurality of planet gears454, and intermeshing therewith, is the ring gear456, which is connected via linkages449to a stationary support structure (not shown). In the example ofFIG.4, the ring gear456is stationary and fixed to the linkages449. Each of the planet gears of the plurality of planet gears454includes a pin450about which a respective planet gear rotates.

The gearbox assembly440includes one or more passages to supply the lubricant from the lubrication system200(FIG.2) to the various gears and components of the gearbox assembly340. The one or more passages includes one or more first passages461and one or more second passages463. The one or more first passages461allow the lubricant to flow in an axial direction. For example, the one or more first passages461allow the lubricant to flow through the pin450. The one or more second passages463allow the lubricant to flow in a radial direction. For example, the one or more second passages463allow the lubricant to flow from the one or more first passages461to the various gears (e.g., the sun gear452, one or more of the plurality of planet gears454, and/or the ring gear456).

As shown inFIG.4, the passive auxiliary lubrication system420includes the same auxiliary tank322, as detailed above. The passive auxiliary lubrication system420is in fluid communication with the gearbox assembly440. For example, the auxiliary supply line226is fluidly coupled to the pin450for supplying the auxiliary lubricant201from the auxiliary tank222through the pin450to the gears of the gearbox assembly440(e.g., through the one or more first passages461and the one or more second passages463), as detailed further below.

In the embodiment ofFIG.4, the passive auxiliary lubrication system420includes a lubricant transfer device490. The lubricant transfer device490facilitates transfer of the auxiliary lubricant201from the auxiliary supply line226to the pin450. For example, the auxiliary supply line226is stationary and the pin450rotates with the planet carrier458, as detailed above. In this way, the lubricant transfer device490facilitates transfer of the auxiliary lubricant201from the auxiliary supply line226(stationary) to the pin450(rotating).

The lubricant transfer device490includes one or more seals492(e.g., a labyrinth tooth seal) and a cavity494. The cavity494is annular and is fluidly coupled to the auxiliary supply line226. The one or more seals492defines a portion of the cavity494and engages with a portion of the planet carrier458. For example, the one or more seals492extend axially between the auxiliary supply line226and the planet carrier458. The auxiliary lubricant201flows into the cavity494through the auxiliary supply line226, and the cavity494is pressurized with the auxiliary lubricant201. For example, the auxiliary lubricant201flows generally axially from the auxiliary supply line226into the cavity494. The one or more seals492prevent the auxiliary lubricant201from flowing out of the cavity494in a radial direction. The one or more first passages461are radially aligned with the respective cavity494. In this way, the auxiliary lubricant201flows from the cavity494to the one or more first passages461as the planet carrier458rotates. Thus, the auxiliary lubricant201is supplied from the cavity494to the one or more first passages461.

FIG.5Ashows a schematic partial cross-sectional side view of another gearbox assembly540and another passive auxiliary lubrication system520(shown schematically inFIG.5A).FIG.5Ashows only a portion of the passive auxiliary lubrication system520. The passive auxiliary lubrication system520may include the same or similar components and functionality as the embodiments shown inFIGS.2and3.

The passive auxiliary lubrication system520includes a lubricant transfer device590. The lubricant transfer device590facilitates transfer of the auxiliary lubricant201from an auxiliary supply line526to the gearbox assembly540, as detailed below. The lubricant transfer device590includes a stationary manifold529and a transfer manifold596. The stationary manifold529is connected to a static structure of the engine10through a flexible component531. The flexible component531may allow the lubricant transfer device590to move with the gearbox assembly540due to, for example, vibrations associated with the engine10. The auxiliary supply line526is fluidly coupled to the stationary manifold529. In some examples, the auxiliary supply line526may include a plurality of auxiliary supply lines526and each of the plurality of auxiliary supply lines526may be fluidly coupled to the stationary manifold529. In some examples, the portion of the auxiliary supply line526shown inFIG.5Amay include an annular component.

FIG.5Bis an enlarged partial cross-sectional side view of the lubricant transfer device590isolated from the gearbox assembly540(FIG.5A). The lubricant transfer device590includes one or more seals592(e.g., a labyrinth tooth seal) and a cavity594. The stationary manifold529includes an annular component defining an internal passage595.

The transfer manifold596is annular and includes one or more internal passages597extending in a generally axial direction therethrough. In some examples, the one or more internal passages597include a single annular passage. The transfer manifold596includes one or more axial apertures599. Each of the one or more axial apertures599is fluidly coupled to a different pin450(e.g., to the one or more first passages461of a respective pin450) (FIG.5A). In some examples, the one or more internal passages597include a plurality of internal passages597. Each of the plurality of internal passages597is fluidly coupled to a different pin450(FIG.5A). The transfer manifold596is radially spaced from the stationary manifold529to define the cavity594.

The cavity594is annular and is fluidly coupled to the stationary manifold529and is fluidly coupled to the transfer manifold596. The stationary manifold529includes one or more apertures, also referred to as stationary manifold apertures591, and the transfer manifold596includes one or more apertures, also referred to as transfer manifold apertures593. The stationary manifold apertures591extend radially through an axial wall of the stationary manifold529. The transfer manifold apertures593extend radially though an axial wall of the transfer manifold596.

The axial wall of stationary manifold529is spaced radially from the axial wall of the transfer manifold596. The one or more seals592define a portion of the cavity594and extend from a radially outer portion of the axial wall of the stationary manifold529to a radially inner portion of the axial wall of the transfer manifold596. In this way, the cavity594is defined between the stationary manifold529and the transfer manifold596. The stationary manifold apertures591are located to provide the auxiliary lubricant201to flow from the stationary manifold529to the cavity594. The transfer manifold apertures593are located to receive the auxiliary lubricant201from the cavity594into the one or more internal passages597.

The transfer manifold596is connected to the planet carrier458(FIG.5A) and the one or more internal passages597are generally radially and axially aligned with the one or more first passages461(FIG.5A). In this way, the stationary manifold529is stationary and the transfer manifold596rotates with the planet carrier458(FIG.5A). Thus, the lubricant transfer device590facilitates transfer of the auxiliary lubricant201from the auxiliary supply line526(FIG.5A) (stationary) to a respective pin450(FIG.5A) (rotating) via the stationary manifold529and the transfer manifold596.

In operation, the auxiliary lubricant201is supplied from the auxiliary supply line526into the stationary manifold529(e.g., into the internal passage595), as indicated by the arrow501. The auxiliary lubricant201is then supplied from the stationary manifold529into the cavity594, and the cavity594is pressurized with the auxiliary lubricant201. For example, the auxiliary lubricant201flows generally radially from the stationary manifold529into the cavity594via the stationary manifold apertures591. The one or more seals592prevent the auxiliary lubricant201from flowing out of the cavity594in an axial direction. The respective transfer manifold apertures593are aligned with the cavity594. In this way, the auxiliary lubricant201flows from the cavity594to the one or more internal passages597of the transfer manifold596via the respective transfer manifold apertures593(as indicated by the arrow503). The auxiliary lubricant201flows through the one or more internal passages597and into the one or more first passages461(FIG.5A) (as indicated by the arrow505). Thus, the auxiliary lubricant201is supplied from the cavity594to the one or more first passages461(FIG.5A) of each respective pin450(FIG.5A).

The selection between using the lubricant transfer device490(FIG.4) or using the lubricant transfer device590(FIGS.5A and5B) for transferring the lubricant from a static component (e.g., auxiliary supply line226,526) to a rotating component (e.g., the pin450) may be based on several factors. For example, the factors may include geometric constraints of the engine10and an effectiveness of the sealing arrangement (e.g., a labyrinth tooth seal or a face seal) for a particular application (e.g., transferring the lubricant axially or transferring the lubricant radially).

FIG.6is a flow diagram of an exemplary method600of lubricating the gearbox assembly40of the engine10. While the embodiment of the method600makes primary reference toFIG.1and the gearbox assembly40, the method600may, of course, be performed with any of the gearbox assemblies or any of the passive auxiliary lubrication systems ofFIGS.2to5B, detailed herein. In step605, the method600includes supplying lubricant from the primary lubrication system202to the auxiliary tank222of the passive auxiliary lubrication system220through the auxiliary tank feed line224. For example, the pump206of the primary lubrication system202pumps lubricant from the primary tank204to the auxiliary tank222, as detailed above. In step610, the method600includes passively pressurizing the lubricant in the auxiliary tank222. For example, the auxiliary tank222is passively pressurized by the piston230and/or is passively pressurized by the compressor bleed air, as detailed above. In this way, the auxiliary tank222is charged, as detailed above.

When the auxiliary tank222is charged, in step615, the method600includes determining whether a pressure in the primary lubrication system202is less than a pressure in the auxiliary tank222. For example, the first valve225closes when the auxiliary tank222has been charged and the second valve227remains closed. In step620, when the pressure in the primary lubrication system202is greater than or equal to the pressure in the auxiliary tank222(step615: NO), the method600includes supplying the lubricant from the primary lubrication system202to the gearbox assembly40. For example, the pump206pumps the lubricant from the primary tank204and supplies the lubricant from the primary tank204to the gearbox assembly40, as detailed above.

In step625, when the pressure in the primary lubrication system202is less than the pressure in the auxiliary tank222(step615: YES), the method600includes supplying the lubricant in the auxiliary tank222to the gearbox assembly40through the auxiliary supply line226. For example, the auxiliary supply line226includes a valve (e.g., the second valve227) that opens when the pressure in the auxiliary tank222is greater than the pressure in the primary lubrication system202, as detailed above. Thus, the passive auxiliary lubrication system220supplies the lubricant from the auxiliary tank222to the gearbox assembly40when the pressure in the primary lubrication system202decreases below a predetermined threshold (e.g., during an abnormal event).

Embodiments of the present disclosure detailed herein provide for a passive auxiliary lubrication system that ensures a supply of lubricant to a gearbox assembly during abnormal events when the primary lubrication system is unavailable. The passive auxiliary lubrication system provides the lubrication to the gearbox assembly without the use of a pump or additional control systems. The present disclosure also provides for a transfer device that enables the passive auxiliary lubrication system to transfer the lubrication from a non-rotating component (e.g., the auxiliary supply line) to a rotating component of the gearbox assembly (e.g., the rotating planet gears). Thus, the embodiments of the present disclosure provide for an auxiliary lubrication system that ensures lubricant is supplied to the gearbox assembly when the primary lubrication system is unable to supply lubrication to the gearbox assembly, without the use of additional pumps or control systems.

Further aspects of the present disclosure are provided by the subject matter of the following clauses.

A passive auxiliary lubrication system for supplying lubricant to a gearbox assembly of an engine comprises an auxiliary tank for storing lubricant and an auxiliary tank feed line. The auxiliary tank for storing lubricant is passively pressurized. The auxiliary tank feed line is fluidly coupled with the auxiliary tank and a primary lubrication system. The lubricant is supplied to the auxiliary tank from the primary lubrication system through the auxiliary tank feed line and the lubricant is passively pressurized in the auxiliary tank. An auxiliary supply line is fluidly coupled with the auxiliary tank and the gearbox assembly. The lubricant in the auxiliary tank is supplied to the gearbox assembly through the auxiliary supply line.

The passive auxiliary lubrication system of the preceding clause, further including a compressor bleed air line that fluid couples the auxiliary tank to a compressor section of the engine such that the auxiliary tank receives bleed air from the compressor section to passively pressurize the auxiliary tank.

The passive auxiliary lubrication system of any preceding clause, the auxiliary tank including a piston for passively pressurizing the lubricant in the auxiliary tank.

The passive auxiliary lubrication system of any preceding clause, the piston being spring-loaded.

The passive auxiliary lubrication system of any preceding clause, the auxiliary tank feed line including a first valve. The first valve operable to supply the lubricant from the primary lubrication system to the auxiliary tank when a pressure in the primary lubrication system is greater than a pressure in the auxiliary tank.

The passive auxiliary lubrication system of any preceding clause, the auxiliary supply line further including a second valve. The second valve operable to supply the lubricant from the auxiliary tank to the gearbox assembly when the pressure in the auxiliary tank is greater than the pressure in the primary lubrication system.

The passive auxiliary lubrication system of any preceding clause, further comprising a lubricant transfer device. The lubricant transfer device includes a cavity fluidly coupled to the auxiliary supply line and fluidly coupled to a plurality of planet gears on a rotating planet carrier. The plurality of the planet gears has one or more passages and the cavity receiving the lubricant from the auxiliary supply line and supplying the lubricant to the one or more passages of the plurality of planet gears as the rotating planet carrier rotates.

The passive auxiliary lubrication system of any preceding clause, the cavity being defined by one or more seals extending axially between the auxiliary supply line and the rotating planet carrier.

The passive auxiliary lubrication system of any preceding clause, the cavity being axially and radially aligned with the one or more passages of the plurality of planet gears such that the lubricant is supplied axially from the cavity to the one or more passages of the plurality of planet gears.

The passive auxiliary lubrication system of any preceding clause, the lubricant transfer device including a transfer manifold having one or more internal passages, the one or more internal passages of the transfer manifold being fluidly coupled to the cavity and fluidly coupled to the one or more passages of the plurality of planet gears.

The passive auxiliary lubrication system of any preceding clause, the cavity being defined by one or more seals extending radially between a stationary manifold and the transfer manifold.

The passive auxiliary lubrication system of any preceding clause, the stationary manifold including one or more stationary manifold apertures and the transfer manifold including one or more transfer manifold apertures such that the lubricant is supplied radially from stationary manifold into the cavity through the one or more stationary manifold apertures, and the lubricant is supplied from the cavity to the one or more internal passages of the transfer manifold through the one or more transfer manifold apertures to supply the lubricant to the one or more passages of the plurality of planet gears.

A method of lubricating a gearbox assembly of an engine, the method comprising supplying a lubricant from a primary lubrication system to an auxiliary tank of a passive auxiliary lubrication system through an auxiliary feed line, passively pressurizing the lubricant in the auxiliary tank, and supplying the lubricant from the auxiliary tank to the gearbox assembly through an auxiliary supply line when a pressure in the primary lubrication system is less than a pressure in the auxiliary tank.

The method of any preceding clause, the supplying the lubricant from the auxiliary tank to the gearbox assembly including supplying the lubricant from the auxiliary tank to the gearbox assembly without a pump.

The method of any preceding clause, the passively pressurizing the lubricant in the auxiliary tank including supplying bleed air from a compressor section of the engine to the auxiliary tank.

The method of any preceding clause, the auxiliary tank including a piston, and the passively pressurizing the lubricant in the auxiliary tank including pressurizing the lubricant in the auxiliary tank with the piston.

The method of any preceding clause, the piston being spring-loaded.

The method of any preceding clause, the gearbox assembly including a rotating planet carrier containing a plurality of planet gears housing one or more passages. The supplying the lubricant from the auxiliary tank to the gearbox assembly further includes supplying the lubricant from the auxiliary supply line to a cavity of a lubricant transfer device, and supplying the lubricant from the cavity to the one or more passages of the plurality of planet gears as the rotating planet carrier rotates.

The method of any preceding clause, the supplying the lubricant from the cavity to the one or more passages including supplying the lubricant axially from the cavity to the one or more passages.

The method of any preceding clause, the supplying the lubricant from the cavity to the one or more passages including supplying the lubricant radially to a transfer manifold of the lubricant transfer device.

Although the foregoing description is directed to the preferred embodiments, other variations and modifications will be apparent to those skilled in the art and may be made without departing from the spirit or the scope of the disclosure. Moreover, features described in connection with one embodiment may be used in conjunction with other embodiments, even if not explicitly stated above.