Lubrication system and method of lubricating gearbox assembly

Abstract

A lubrication system (100) for a turbine engine (10) includes a reservoir (130) storing lubricant, a primary lubricant supply circuit (120) including a primary supply pump (122) fluidly coupled to the reservoir (130), and an auxiliary lubricant supply circuit (140) including an auxiliary supply pump (142) fluidly coupled to the reservoir (130). The clutch (144) is mechanically coupled to the auxiliary supply pump (142), and the clutch (144) is configured to engage the auxiliary supply pump (142) and a shaft of the turbine engine (10) when activated. The lubrication system (100) also includes a pressure sensor (182) that monitors a lubricant pressure within the primary lubricant supply circuit (120). The clutch (144) is activated to engage the auxiliary supply pump (142) and the shaft of the turbine engine (10) when the lubricant pressure within the primary lubricant supply circuit (120) drops below a predetermined lubricant threshold.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to turbine engines, and more specifically, to a lubrication system of a gearbox assembly of a turbine engine. BACKGROUND

[0002] Gas turbine engines, commonly used for aircraft propulsion, utilize a continuous supply of lubrication to various components to ensure proper function and longevity. Traditionally, lubrication is provided by a primary lubrication system that draws oil from a sump and circulates the oil through the engine via a shaft driven pump. However, during in-flight shutdown and / or windmill conditions, where the engine fan continues to rotate due to external airflow, but the engine itself is not running, the shaft, and in turn the shaft driven pump, can not rotate. Stagnation of the pump can result in a cessation of oil flow to the gearbox assembly, which can result in increased wear and / or component failure over time. BRIEF DESCRIPTION OF DRAWINGS

[0003] The embodiments set forth in the attached drawings are illustrative and exemplary in nature, and are not intended to limit the subject matter defined by the claims. The following detailed description of illustrative embodiments can be understood when considered in connection with the following drawings, in which like structures are referred to by like reference numerals, and in which:

[0004] Figure 1 schematically depicts a cross-sectional view of a turbine engine taken along a centerline axis of the turbine engine, in accordance with one or more embodiments shown and described herein;

[0005] Figure 2 schematically depicts a lubrication system of a gearbox assembly of a turbine engine, in accordance with one or more embodiments shown and described herein;

[0006] Figure 3A schematically depicts a normal operating mode of a lubrication system of Figure 2 , in accordance with one or more embodiments shown and described herein;

[0007] Figure 3B schematically depicts a backup operating mode of a lubrication system of Figure 2 , in accordance with one or more embodiments shown and described herein; and

[0008] Figure 4 schematically depicts a flowchart of a method of supplying lubricant to a gearbox assembly using a lubrication system of Figure 2 , in accordance with one or more embodiments shown and described herein; and DETAILED DESCRIPTION

[0009] Embodiments described herein relate to turbine engines, lubrication systems, and methods of supplying lubrication to a gearbox assembly of a turbine engine. A lubrication system of a turbine engine can include a reservoir storing a lubricant, a primary lubricant supply circuit including a primary supply pump fluidly coupled to the reservoir, and an auxiliary lubricant supply circuit including an auxiliary supply pump fluidly coupled to the reservoir. A clutch can be mechanically coupled to the auxiliary supply pump, and when activated, the clutch can engage the auxiliary supply pump and a shaft of the turbine engine.

[0010] In these embodiments, the lubrication system can further include a sensor, such as a pressure sensor that monitors a pressure of the lubricant within the primary lubricant supply circuit. When the pressure of the lubricant within the primary lubricant supply circuit falls below a predetermined lubricant threshold, the clutch is activated to engage the auxiliary supply pump and the shaft of the turbine engine. By monitoring the pressure of the lubricant within the primary lubricant supply circuit, consistent lubrication of the turbine engine can be maintained using the auxiliary lubricant supply circuit when the primary lubricant supply circuit is inactive, thereby ensuring operational readiness and longevity of the turbine engine while reducing the risk of wear and potential engine failure.

[0011] As described herein, conventional lubrication systems of turbine engines rely on a continuous supply of lubrication to various components to ensure proper function and longevity. In particular, gearbox assemblies used to transmit engine-generated mechanical energy to fans and / or propellers include multiple bearings and gears that require continuous lubrication during operation to minimize friction and wear.

[0012] Conventionally, turbine engine lubrication systems draw oil from a sump and circulate the oil through the engine via a pump coupled to a spool shaft. While this configuration can effectively function during normal engine conditions, when the turbine engine is operated in an in-flight shut down (IFSD) condition or a windmill condition (where the engine fan continues to rotate due to external airflow when the engine itself is not running), oil can stop flowing through the system. In these embodiments, the stoppage of oil flow through the lubrication system can result in increased wear over time on various components of the gearbox assembly.

[0013] Further, conventional lubrication systems are ill-equipped to handle the changing operating conditions of advanced turbine engines. For example, conventional lubrication systems can be unable to provide sufficient lubricant supply to the gearbox assembly of a turbine engine under low flow and / or high flow conditions, and can likewise struggle to ensure consistent lubricant flow when the rotational direction of the fan and / or propeller of the turbine engine is reversed. The disclosed lubrication system addresses these shortcomings by providing an auxiliary lubrication system that allows for consistent and / or continuous lubricant flow to the gearbox assembly of a turbine engine during all operating phases, thereby ensuring turbine engine operational readiness and longevity while reducing the risk of wear and potential engine failure.

[0014] Various embodiments of turbine engines, lubrication systems, and methods of lubricating a gearbox assembly of a turbine engine are described in greater detail herein. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0015] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, unless otherwise explicitly specified, all embodiments described herein are intended to be exemplary.

[0016] As used herein, the terms “first” and “second” can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0017] The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle and refer to the normal operating attitude of the turbine engine or vehicle.

[0018] The terms “upstream” and “downstream” refer to the relative direction with respect to the flow in a path. For example, with respect to fluid flow, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. However, the terms “upstream” and “downstream” as used herein can also refer to electrical current.

[0019] Unless otherwise stated herein, the terms “coupled,” “fixed,” “attached,” “connected,” and the like, mean either directly coupled, fixed, attached, or connected, or indirectly coupled, fixed, attached, or connected through one or more intermediate components or features.

[0020] The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

[0021] As used herein, the terms "axial" and "axially" refer to a direction and orientation that extends substantially parallel to a centerline of the turbine engine. Further, the terms "radial" and "radially" refer to a direction and orientation that extends substantially perpendicular to the centerline of the turbine engine. Additionally, as used herein, the terms "circumferential" and "circumferentially" refer to a direction and orientation that extends arcuately about the centerline of the turbine engine.

[0022] As used herein throughout the description and claims, approximate language is applied to modify any quantitative representation that can permit variations without changing the basic function to which it is directed. Thus, a value modified by a term or terms, such as "about," "approximately,” and “substantially,” are not limited to the precise value specified. In at least some instances, the approximate language can correspond to the precision of an instrument for measuring the value, or the precision of the method or machine used to construct or manufacture the component and / or system. In at least some instances, the approximate language can correspond to the precision of an instrument for measuring the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, the approximate language can refer to a margin of error within 1%, 2%, 4%, 5%, 10%, 15%, or 20% of a single value, a range of values, and / or an endpoint of a defined range of values.

[0023] Herein and throughout the description and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0024] Referring now to the drawings, Figure 1 is a schematic cross-sectional view of a turbine engine 10 taken along a centerline axis of the turbine engine 10 in accordance with an embodiment of the present disclosure. As Figure 1 shown, the turbine engine 10 defines an axial direction A (extending parallel to a longitudinal centerline axis 12 provided for reference) and a radial direction R that is perpendicular to the axial direction A. Generally, the turbine engine 10 includes a fan section 14 and a core turbine engine 16 disposed downstream of the fan section 14.

[0025] The depicted core turbine engine 16 generally includes a casing 18 that is substantially tubular and defines an annular inlet 20. As Figure 1As schematically shown, the outer casing 18 encloses in serial flow relationship: a compressor section 21 including a booster or low pressure (LP) compressor 22 followed downstream by a high pressure (HP) compressor 24; a combustion section 26; a turbine section 27 including a high pressure (HP) turbine 28 followed downstream by a low pressure (LP) turbine 30; and an ejection exhaust nozzle section 32. A high pressure (HP) shaft 34 or spool drivingly connects the HP turbine 28 to the HP compressor 24 to cause the HP turbine 28 and the HP compressor 24 to rotate in unison. A low pressure (LP) shaft 36 drivingly connects the LP turbine 30 to the LP compressor 22 to cause the LP turbine 30 and the LP compressor 22 to rotate in unison. The compressor section 21, the combustion section 26, the turbine section 27, and the ejection exhaust nozzle section 32 together define a core air flowpath.

[0026] For the exemplary embodiment depicted in Figure 1 , the fan section 14 includes a fan 38 (e.g., a variable pitch fan) having a plurality of fan blades 40 coupled to a disk 42 in a spaced apart manner. As Figure 1 depicted in , the fan blades 40 extend outwardly in a generally radial direction R from the disk 42. Each fan blade 40 is rotatable relative to the disk 42 about a pitch axis P by virtue of the fan blades 40 being operably coupled to an actuation member 44 configured to collectively and uniformly change the pitch of the fan blades 40. The fan blades 40, the disk 42, and the actuation member 44 are rotatable together about the centerline axis 12 via a fan shaft 45 powered by the LP shaft 36 across a power gear box (also referred to as a gear box assembly 46). The gear box assembly 46 is schematically shown in Figure 1 . The gear box assembly 46 includes a plurality of gears for adjusting the rotational speed of the fan shaft 45, and thus the fan 38, relative to the rotational speed of the LP shaft 36 to a more efficient rotational fan speed.

[0027] Still referring to the exemplary embodiment of Figure 1 , the disk 42 is covered by a rotatable fan hub 48 that is aerodynamically shaped to facilitate airflow through the plurality of fan blades 40. Further, the fan section 14 includes an annular fan casing or nacelle 50 that circumferentially surrounds the fan 38 and / or at least a portion of the core turbine engine 16. The nacelle 50 is supported relative to the core turbine engine 16 by a plurality of circumferentially spaced apart outlet guide vanes 52. Further, a downstream section 54 of the nacelle 50 extends over an outer portion of the core turbine engine 16 to define a bypass airflow passage 56 therebetween.

[0028] During operation of the turbine engine 10, an amount of air 58 enters the turbine engine 10 through the nacelle 50 and / or an inlet 60 of the fan section 14. As the amount of air 58 passes through the fan blades 40, a first portion of air 62 is directed or channeled into the bypass airflow passage 56, while a second portion of air 64 is directed or channeled into an upstream section of the core airflow path, or more specifically, into the annular inlet 20 of the LP compressor 22. The ratio between the first and second portions of air 62, 64 is commonly referred to as a bypass ratio. The second portion of air 64 then has its pressure increased as it is channeled through the HP compressor 24 and into the combustion section 26, where the highly pressurized air is mixed with and combusted with fuel to provide combustion gases 66.

[0029] The combustion gases 66 are directed into and expanded through the HP turbine 28, where a portion of thermal and / or kinetic energy from the combustion gases 66 is extracted via sequential stages of HP turbine stator vanes 68 coupled to the outer casing 18 and HP turbine rotor blades 70 coupled to the HP shaft 34, thus rotating the HP shaft 34 in support of operation of the HP compressor 24. The combustion gases 66 are then directed into and expanded through the LP turbine 30. Here, a second portion of thermal and kinetic energy is extracted from the combustion gases 66 via sequential stages of LP turbine stator vanes 72 coupled to the outer casing 18 and LP turbine rotor blades 74 coupled to the LP shaft 36, thus rotating the LP shaft 36 in support of operation of the LP compressor 22 and rotation of the fan 38 via the gear box assembly 46.

[0030] The combustion gases 66 are subsequently directed through the jet exhaust nozzle section 32 of the core turbine engine 16 to provide propulsive thrust. At the same time, the first portion of air 62 has its pressure significantly increased as it is directed through the bypass airflow passage 56 before being discharged from a fan nozzle exhaust section 76 of the turbine engine 10, also providing propulsive thrust. The HP turbine 28, the LP turbine 30, and the jet exhaust nozzle section 32 at least partially define a hot gas path 78 for directing the combustion gases 66 through the core turbine engine 16.

[0031] Figure 1The depicted turbine engine 10 is by way of example only. In other example embodiments, the turbine engine 10 can have any other suitable configuration. For example, in other example embodiments, the fan 38 can be configured in any other suitable manner (e.g., as a fixed-pitch fan) and can also be supported using any other suitable fan frame configuration. Moreover, in other example embodiments, any other suitable number or configuration of compressors, turbines, shafts, or combinations thereof can be provided. In still other example embodiments, aspects of the present disclosure can be incorporated into any other suitable gas turbine engine (e.g., a turbofan engine, a propfan engine, a turbojet engine, and / or a turboshaft engine).

[0032] Referring now to Figure 2 , a lubrication system 100 for the turbine engine 10 is depicted. In these embodiments, the lubrication system 100 can include a primary lubricant supply circuit 120 and an auxiliary lubricant supply circuit 140 that can operate in tandem to provide continuous lubrication to various components of the gearbox assembly 46 (e.g., bearings 146, gears, etc.) during various operating conditions of the turbine engine 10, as will be described in greater detail herein. While the bearings 146 are schematically depicted as being separate from the gearbox assembly 46, it should be understood that the bearings 146 are part of the gearbox assembly 46. However, the bearings 146 are depicted as being separate from the gearbox assembly 46 merely to more clearly illustrate the flow path of lubricant between the reservoir 130, the primary supply pump 122, the auxiliary supply pump 142, and the shuttle valve 170.

[0033] In these embodiments, the primary lubricant supply circuit 120 can include a primary supply pump 122 that can be coupled to the accessory gearbox 150. As Figure 2 depicted, the accessory gearbox 150 can be mechanically coupled to the HP shaft 34 such that rotation of the HP shaft 34 (as described herein with reference to Figure 1 ) drives the accessory gearbox 150, which in turn drives the primary supply pump 122.

[0034] Still referring to Figure 2 , the primary supply pump 122 can be fluidly coupled to a reservoir 130, such as a lubricant reservoir, that can be configured to store lubricant (e.g., oil, etc.). When activated, the primary supply pump 122 can draw lubricant from the reservoir 130 and circulate the lubricant to the bearings 146 and other similar components of the turbine engine 10, as will be described in greater detail herein with reference to Figure 3A .

[0035] As Figure 2As further depicted, the auxiliary lubricant supply circuit 140 can similarly include an auxiliary supply pump 142 that can be mechanically coupled to the LP shaft 36, which in turn is mechanically coupled to the fan 38 via a clutch 144. In these embodiments, the clutch 144 can be configured to engage and / or disengage the auxiliary supply pump 142 with the LP shaft 36 based on an operating state of the turbine engine 10. As referred to herein, the term“engage” refers to the clutch 144 being operably connected or coupled to the auxiliary supply pump 141 by any suitable means integral with the clutch 144 and / or the auxiliary supply pump 142 or some intermediate component. Similarly, the term“disengage” refers to a state in which the clutch 144 is not operably connected or coupled to the auxiliary supply pump 142. In these embodiments, the auxiliary supply pump 142 can be similarly fluidly coupled to the reservoir 130 such that, when the auxiliary supply pump 142 is activated (e.g., when the clutch 144 engages the auxiliary supply pump 142 and the LP shaft 36), rotation of the LP shaft 36 can power the auxiliary supply pump 141 to draw lubricant from the reservoir 130 and circulate the lubricant to the bearing 146 and other similar components of the turbine engine 10.

[0036] Further, in some embodiments, the auxiliary supply pump 142 can be mechanically coupled to the fan shaft 45. For example, in the embodiments described herein, the turbine engine 10 can experience a failure condition in which the fan shaft 45 continues to rotate while the LP shaft 36 stalls (e.g., due to a shaft breakage, a breakage in the coupling between the shaft and the gearbox 46, etc.). Although not shown, by coupling the auxiliary supply pump 142 directly to the fan shaft 45 independent of the LP shaft 36, continued operation of the auxiliary lubricant supply circuit 140 during the LP shaft 36 failure condition can be ensured.

[0037] In the embodiments described herein, it should be further understood that the auxiliary supply pump 142 can be a bi-directional auxiliary supply pump capable of pumping lubricant in a first direction and / or a second direction opposite the first direction. By configuring the auxiliary supply pump 142 as a bi-directional pump, reverse rotation of the fan 38 when the turbine engine 10 is shut down can be accommodated, as will be described in greater detail herein.

[0038] Still referring to Figure 2lubrication system 100 can also include a plurality of thermal management components configured to control the temperature and / or flow of lubricant through the primary lubricant supply circuit 120 and / or the auxiliary lubricant supply circuit 140. For example, the lubrication system 100 can include a heat exchanger 160 configured to cool the lubricant by transferring heat from the lubricant to another medium (e.g., air, etc.) passing through and / or past the heat exchanger 160, such as an air / lubricant (e.g., oil) cooler. In these embodiments, the heat exchanger 160 can include a heat exchanger inlet that receives the lubricant and a heat exchanger outlet that dispenses the cooled lubricant back into the lubrication system 100. As the lubrication (e.g., between the heat exchanger inlet and the heat exchanger outlet) flows through the heat exchanger 160, heat from the lubricant can be conducted through the heat exchanger 160 and transferred to the air flowing through the heat exchanger 160 to cool the lubricant. In these embodiments, the airflow used to cool the lubricant can be generated by forward travel of the turbine engine 10 during operation.

[0039] In the embodiments described herein, the lubrication system 100 can also include a shuttle valve 170 that can be configured to direct the flow of lubricant from the primary lubricant supply circuit 120 and / or the auxiliary lubricant supply circuit 140 through the heat exchanger 160 for temperature regulation or around (e.g., bypass) the heat exchanger 160 based on the operating mode of the turbine engine 10. Accordingly, in these embodiments, it should be understood that the primary supply pump 122 and the auxiliary supply pump 142 can each be fluidly coupled to the shuttle valve 170 such that the primary supply pump 122 and the auxiliary supply pump 142 can draw lubricant from the reservoir 130 and direct the lubricant to the shuttle valve 170, which in turn directs to the heat exchanger 160. It should be understood that the shuttle valve 170 can alternatively be any other suitable valve. It should be understood that the shuttle valve 170 can be passively controlled or actively controlled. In embodiments where the shuttle valve 170 is passively controlled, the shuttle valve 170 can operate in response to the pressure within the lubrication system 100. For example, if the pressure within the lubrication system 100 exceeds a predetermined pressure, the shuttle valve 170 can operate in a first state to allow the flow of lubricant through the heat exchanger 160. Alternatively, for example, if the pressure within the lubrication system 100 is below a predetermined pressure, the shuttle valve 170 can operate in a second state to allow the flow of lubricant around the heat exchanger 160. In other embodiments, the shuttle valve 170 can be manually operated by an operator, such as an engine controller. In other embodiments, the shuttle valve 170 can be controlled via a controller (e.g., an electronic control unit) configured to detect the pressure, temperature, or any other suitable parameter within the lubrication system 100 and operate the shuttle valve 170 appropriately.

[0040] In addition to shuttle valve 170, lubrication system 100 can also include a plurality of check valves 172 disposed between shuttle valve 170 and bearing 146. In these embodiments, the plurality of check valves 172 can ensure that lubricant in lubrication system 100 flows in a single direction (e.g., from shuttle valve 170 to bearing 146) in order to prevent reverse lubricant flow that can cause contamination and / or damage to components within turbine engine 10. For example, in these embodiments, when lubricant is flowing in the desired direction, the lubricant can generate a pressure that opens at least one of the plurality of check valves 172 to allow lubricant to pass through lubrication system 100. However, when lubricant attempts to flow in the opposite direction, the differential pressure of the lubricant changes and the plurality of check valves 172 close to seal the valve and block the flow of lubricant. In the embodiments described herein, the plurality of check valves 172 can include ball check valves, swing check valves, lift check valves, diaphragm check valves, or any other suitable check valve. Furthermore, although the plurality of check valves 172 are depicted as being disposed between shuttle valve 170 and bearing 146, it should be understood that in some embodiments, additional check valves 172 can be disposed within lubrication system 100 (e.g., between primary supply pump 122 and / or auxiliary supply pump 142 and heat exchanger 160, etc.).

[0041] Still referring to Figure 2 , lubrication system 100 can also include a switching mechanism 180 that can be configured to determine an operating state of turbine engine 10 to engage and / or disengage auxiliary lubricant supply circuit 140. For example, switching mechanism 180 can include a switch that is transitionable between an open position in which clutch 144 is engaged with auxiliary supply pump 142 and a closed position in which clutch 144 is disengaged from auxiliary supply pump 142. In these embodiments, switching mechanism 180 can be configured as a passive system (e.g., in which the presence of electrical power and / or lubricant pressure within primary lubricant supply circuit 120 controls operation of the switch) and / or an active system.

[0042] As Figure 2 further depicts, switching mechanism 180 can include a sensor that monitors the pressure of lubricant flowing between primary supply pump 122 and shuttle valve 170, such as pressure sensor 182 (e.g., a lubricant pressure sensor). In these embodiments, switching mechanism 180 can also include a power source 184 that provides electrical power to switching mechanism 180. The operation of switching mechanism 180 and lubrication system 100 will be described in greater detail herein with reference to Figure 3A and Figure 3B .

[0043] Reference is now made to Figure 3A and Figure 3BThe operation of the lubrication system 100 will be described with reference to various operating conditions of the turbine engine 10. For example, in the embodiments described herein, the turbine engine 10 can include a normal operating mode in which the turbine engine 10 is powered on and a backup operating mode in which the turbine engine 10 is shut down and / or enters a windmilling operating mode. As provided herein, the term “windmilling” can refer to a condition of the turbine engine 10 in which the fan 38 of the turbine engine 10 continues to rotate due to movement of the aircraft and / or environmental winds even if the turbine engine 10 is powered off. In the embodiments described herein, the windmilling condition can occur during an in-flight shutdown (“IFSD”) and / or when the aircraft is on the ground and the turbine engine 10 is powered off.

[0044] As Figure 3A As depicted in FIG. 1, in the normal operating mode, lubricant flows through the lubrication system 100 as described herein. For example, in the normal operating mode, the turbine engine 10 is powered on such that the HP shaft 34 drives the accessory gearbox 150 and the accessory gearbox 150 drives the primary supply pump 122 of the primary lubricant supply circuit 120. In these embodiments, with the primary supply pump 122 activated, the primary supply pump 122 can draw lubricant from the reservoir 130 and circulate the lubricant through the bearings 146 and / or the heat exchanger 160 as described herein.

[0045] During normal operation (e.g., with the turbine engine 10 turned on and the primary lubricant supply circuit 120 activated), the pressure sensor 182 of the switching mechanism 180 can monitor the pressure of the lubricant flowing through the primary lubricant supply circuit 120. In these embodiments, the pressure sensor 182 can ensure that the lubricant pressure remains at or above a predetermined lubricant threshold sufficient to circulate the lubricant through the primary lubricant supply circuit 120 as described herein.

[0046] Still referring to Figure 3ADuring normal operating modes of the turbine engine 10, the clutch 144 can maintain the auxiliary supply pump 142 of the auxiliary lubricant supply circuit 140 in a disengaged position (e.g., relative to the LP shaft 36) when the lubricant pressure within the primary lubricant supply circuit 120 remains equal to or above a predetermined lubricant threshold. In these embodiments, by disengaging the auxiliary supply pump 142 from the LP shaft 36, the auxiliary supply pump 142 can be inactive during normal operating modes of the turbine engine 10 (e.g., during operation of the primary lubricant supply circuit 120). It should be appreciated that in the embodiments described herein, only one of the primary lubricant supply circuit 120 or the auxiliary lubricant supply circuit 140 can be active at a time. For example, each of the auxiliary supply pump 142 and the primary supply pump 122 can be configured to maintain a particular lubricant pressure and lubricant flow rate within the lubrication system 100. In the event that each of the auxiliary supply pump 142 and the primary supply pump 122 are activated simultaneously, the auxiliary supply pump 142 and the primary supply pump 122 together can generate a lubricant pressure and / or a lubricant flow rate that exceeds the limits of the lubrication system 100, which can result in a decrease in the effectiveness of lubrication and cooling, and in some cases, a failure of the lubrication system 100.

[0047] Referring now to Figure 3B The lubrication system 100 can also operate in a backup operating mode in which the auxiliary lubricant supply circuit 140 is activated. For example, when the turbine engine 10 is in a windmilling operating mode (e.g., when the turbine engine 10 is de-energized and / or during an IFSD), the rotation of the HP shaft 34 can be significantly limited and / or stopped. In these embodiments, components of the accessory gear box 150 (e.g., bearings, gears, etc.) that operate using rotational motion of the HP shaft 34 can exert a resistance force on the HP shaft 34. Moreover, during windmilling operation, airflow through the turbine engine 10 can be minimal because the compressor of the turbine engine 10 can not be actively compressing air such that there is no combustion to drive the turbine engine 10. In these embodiments, because the turbine engine 10 can not be generating power, the HP shaft 34 can not receive the mechanical energy required to rotate when the HP shaft 34 is rotating under normal operating conditions.

[0048] In the embodiments described herein, because the primary supply pump 122 is driven by the HP shaft 34 (e.g., via the accessory gear box 150), inactivity of the HP shaft 34 during backup (e.g., windmilling) operation can prevent the primary supply pump 122 from circulating lubricant through the primary lubricant supply circuit 120. Accordingly, when the primary supply pump 122 stops circulating lubricant through the primary lubricant supply circuit 120, the lubricant pressure within the primary lubricant supply circuit 120 can drop below the predetermined lubricant threshold.

[0049] Still referring to Figure 3B When the pressure sensor 182 of the switching mechanism 180 determines that the lubricant pressure within the primary lubricant supply circuit 120 has dropped below the predetermined lubricant threshold, the switching mechanism 180 can activate the clutch 144, which in turn can cause the auxiliary supply pump 142 to engage with the LP shaft 36 of the turbine engine 10. In these embodiments, while the turbine engine 10 can be shut down and / or in IFSD mode, external forces (e.g., wind, other air flow) can continue to rotate the fan 38, and in turn, the fan shaft 45 during windmill operation.

[0050] In these embodiments, it should be further understood that the clutch 144 can be configured to engage the auxiliary supply pump 142 in various situations, as will be described in greater detail herein. For example, in the embodiments described herein, the clutch 144 can be configured to engage the auxiliary supply pump 142 in the event of a power interruption of the power source 184 and / or in the event that the lubricant pressure within the primary lubricant supply circuit 120 drops below the predetermined lubricant threshold. Further, in some embodiments, the clutch 144 can be passively configured such that the clutch 144 automatically engages the auxiliary supply pump 142 during a power interruption of the power source 184 and / or when the lubricant pressure drops below the predetermined lubricant threshold, enabling the clutch 144 to operate without the use of the switching mechanism 180.

[0051] Still referring to Figure 3B The gearbox assembly 46 can further include a gear ratio that allows the gearbox assembly 46 to rotate at a higher speed than the fan shaft 45. Accordingly, the increased rotational speed of the gearbox assembly 46, even when the turbine engine 10 is shut down and / or in IFSD mode, is able to drive the LP shaft 36, which when activated by the clutch 144, can engage and drive the auxiliary supply pump 142. With the auxiliary supply pump 142 activated, the auxiliary supply pump 142 can draw lubricant from the reservoir 130 and circulate the lubricant through the auxiliary lubricant supply circuit 140 to ensure a continued supply of lubricant throughout the turbine engine 10, even when the primary lubricant supply circuit 120 is inactive.

[0052] Now referring to Figure 3A and Figure 3BIn these embodiments, when the turbine engine 10 is powered on, the primary supply pump 122 can be reactivated such that lubricant is circulated through the primary lubricant supply circuit 120. As the lubricant begins to flow through the primary lubricant supply circuit 120, the pressure sensor 182 of the switching mechanism 180 can determine that the lubricant pressure within the primary lubricant supply circuit 120 meets and / or exceeds the predetermined lubricant threshold, at which point the pressure within the primary lubricant circuit 120 can be used to close the switching mechanism 180 such that the clutch 144 disengages the auxiliary supply pump 142. With the clutch 144 disengaged, the auxiliary supply pump 142 can be disengaged from the LP shaft 36 such that lubricant ceases to flow through the auxiliary lubricant supply circuit 140.

[0053] Although Figure 3A and Figure 3B The auxiliary lubricant supply circuit 140 and the auxiliary supply pump 142 are depicted as being powered via the LP shaft 36, it should be understood that in some embodiments, the lubrication system 100 can also include a separate power source, such as an electrical power supply, for driving the auxiliary supply pump 142. Thus, in these embodiments, the auxiliary supply pump 142 can operate independent of the status of the fan 38 and / or the LP shaft 36 (e.g., in the event of a failure of the fan 38 and / or the LP shaft 36, etc.). Moreover, while activation of the primary lubricant supply circuit 120 and / or the auxiliary lubricant supply circuit 140 is described as being automatically activated via the switching mechanism 180, it should be understood that in some embodiments, the auxiliary lubricant supply circuit 140 can be manually activated when the primary lubricant supply circuit 120 fails to maintain lubricant pressure.

[0054] Turning now to Figure 4 , reference is made to Figure 1 -3, a flowchart of a method 400 of supplying lubricant to the gearbox assembly 46 of the turbine engine 10 is depicted. In these embodiments, the method 400 can initially involve powering on the turbine engine 10 such that the turbine engine 10 enters a normal operating mode, as depicted at block 410. With the turbine engine 10 in the normal operating mode, the method 400 can also involve activating the primary lubricant supply circuit 120 of the lubrication system 100 of the turbine engine 10, as depicted at block 420.

[0055] Once the primary lubricant supply circuit 120 is activated, the method 400 can proceed to block 430, which can involve circulating lubricant from the reservoir 130 positioned within the turbine engine 10 through the primary lubricant supply circuit 120 via the primary supply pump 122 such that the lubricant passes through various components of the gearbox assembly 36 (e.g., the bearing 146) and back to the reservoir 130. In these embodiments, the method steps of block 430 can also involve circulating the lubricant through the heat exchanger 160 to adjust the temperature of the lubricant prior to passing the lubricant through the gearbox assembly 46 and / or returning the lubricant to the reservoir 130.

[0056] Still referring to Figure 4 In these embodiments, the method 400 can also involve shutting down the turbine engine 10 such that the turbine engine 10 enters a backup or windmilling mode of operation, as indicated at block 440. With the turbine engine 10 de-energized, the primary lubricant supply circuit 120 can be deactivated such that the primary supply pump 122 ceases circulating lubricant through the primary lubricant supply circuit 120, and in turn, the gearbox assembly 46 of the turbine engine 10.

[0057] With the turbine engine 10 shut down and the primary lubricant supply circuit 120 deactivated, the method 400 can proceed to block 450, which can involve activating the auxiliary lubricant supply circuit 140. After the auxiliary lubricant supply circuit 140 is activated, the method 400 can proceed to block 460, which can involve circulating lubricant from the reservoir 130 through the auxiliary lubricant supply circuit 140 via the auxiliary supply pump 142 such that the lubricant passes through various components of the gearbox assembly 36 (e.g., the bearing 146) and back to the reservoir 130. In these embodiments, the method steps of circulating lubricant via the auxiliary supply pump 142 can also involve using the clutch 144 to engage the auxiliary supply pump 142 with a shaft of the turbine engine 10 such that rotation of the fan 38 of the turbine engine 10 during the backup (e.g., windmilling) mode of operation can be used to power the auxiliary supply pump 142.

[0058] It should be appreciated that in the embodiments described herein, lubricant can be circulated through the turbine engine 10 via the primary lubricant supply circuit 120 and / or the auxiliary lubricant supply circuit 140 based on the operating mode of the turbine engine 10. For example, the primary lubricant supply circuit 120 can be used to provide lubricant to the gearbox assembly 46 during normal operation (e.g., when the turbine engine 10 is powered on), while the auxiliary lubricant supply circuit 140 can be used to provide lubricant to the gearbox assembly 46 during backup operation (e.g., during windmill conditions). Moreover, the steps of activating and / or deactivating the primary lubricant supply circuit 120 and the auxiliary lubricant supply circuit 140 can be performed any number of times during a flight of the turbine engine 10, as can be necessary for changes in the operating mode of the turbine engine 10 during the flight.

[0059] In some embodiments, the method 400 can also involve automatically activating and / or deactivating the auxiliary lubricant supply circuit 140 with the switching mechanism 180 based on the lubricant pressure within the primary lubricant supply circuit 120. For example, in these embodiments, the switching mechanism 180 can include a pressure sensor 182 configured to monitor the lubricant pressure within the primary lubricant supply circuit 120. When the lubricant pressure falls below a predetermined lubricant threshold, the switching mechanism 180 can automatically activate the auxiliary lubricant supply circuit 140 to provide lubricant to the turbine engine 10. Similarly, when the pressure sensor 182 determines that the lubricant pressure meets and / or exceeds the predetermined lubricant threshold in the primary lubricant supply circuit 120, the switching mechanism 180 can automatically deactivate the auxiliary lubricant supply circuit 140 such that the auxiliary lubricant supply circuit 140 ceases to provide lubricant to the turbine engine 10.

[0060] In view of the above, it should be appreciated that defined herein are a turbine engine, a lubrication system, and a method of lubricating a gearbox assembly in a turbine engine. The lubrication system of the turbine engine includes a reservoir storing a lubricant, a primary lubricant supply circuit including a primary supply pump fluidly coupled to the reservoir, and an auxiliary lubricant supply circuit including an auxiliary supply pump fluidly coupled to the reservoir. A clutch is mechanically coupled to the auxiliary supply pump and, when activated, engages the auxiliary supply pump and a shaft of the turbine engine. The lubrication system further includes a switching mechanism including a pressure sensor that monitors a lubricant pressure of the lubricant within the primary lubricant supply circuit. The clutch engages the auxiliary supply pump and the shaft of the turbine engine when the lubricant pressure within the primary lubricant supply circuit falls below a predetermined lubricant threshold. By monitoring the lubricant pressure of the lubricant within the primary lubricant supply circuit, consistent lubrication of the turbine engine can be maintained with the auxiliary lubricant supply circuit when the primary lubricant supply circuit is inactive, thereby ensuring operational readiness and longevity of the turbine engine while reducing the risk of wear and potential engine failure.

[0061] Further aspects of the embodiments described herein are provided by the subject matter of the following clauses:

[0062] A lubrication system for a turbine engine, comprising: a reservoir configured to store a lubricant; a primary lubricant supply circuit comprising a primary supply pump fluidly coupled to the reservoir; an auxiliary lubricant supply circuit comprising an auxiliary supply pump fluidly coupled to the reservoir; a clutch mechanically coupled to the auxiliary supply pump, the clutch configured to engage the auxiliary supply pump and a shaft of the turbine engine when activated; and a sensor monitoring a lubricant pressure within the primary lubricant supply circuit; wherein the clutch is activated to engage the auxiliary supply pump and the shaft of the turbine engine when the lubricant pressure within the primary lubricant supply circuit falls below a predetermined lubricant threshold.

[0063] The lubrication system according to the preceding clause, further comprising a heat exchanger configured to adjust a temperature of the lubricant circulating through the turbine engine.

[0064] The lubrication system according to any preceding clause, further comprising a shuttle valve fluidly coupled to the heat exchanger, the primary supply pump, and the auxiliary supply pump.

[0065] The lubrication system according to any preceding clause, wherein the shuttle valve is operable to allow the lubricant to pass through the heat exchanger when the temperature of the lubricant exceeds a predetermined temperature threshold.

[0066] The lubrication system according to any preceding clause, wherein the shuttle valve is operable to bypass the lubricant around the heat exchanger when the temperature of the lubricant is below a predetermined temperature threshold.

[0067] The lubrication system according to any preceding clause, wherein the auxiliary supply pump is a bi-directional pump.

[0068] The lubrication system according to any preceding clause, further comprising a plurality of check valves operable to allow the lubricant to flow unidirectionally through the primary lubricant supply circuit and the auxiliary lubricant supply circuit.

[0069] The lubrication system according to any preceding clause, wherein the primary lubricant supply circuit is activated and the auxiliary lubricant supply circuit is deactivated when the turbine engine is powered on.

[0070] The lubrication system of any preceding clause, wherein the primary lubricant supply circuit is deactivated and the auxiliary lubricant supply circuit is activated when the turbine engine is powered down.

[0071] The lubrication system of any preceding clause, wherein the primary supply pump is mechanically coupled to an accessory gear box of the turbine engine such that rotation of the accessory gear box is configured to power the primary supply pump.

[0072] A turbine engine comprising: a fan section comprising a fan; a fan shaft coupled to the fan, the fan shaft configured to rotate the fan; a turbine section comprising a high pressure shaft and a low pressure shaft; a gear box assembly mechanically coupled to the turbine section; and a lubrication system comprising: a reservoir configured to store a lubricant; a primary lubricant supply circuit comprising a primary supply pump fluidly coupled to the reservoir and mechanically coupled to the high pressure shaft of the turbine section; an auxiliary lubricant supply circuit comprising an auxiliary supply pump fluidly coupled to the reservoir and mechanically coupled to the low pressure shaft of the turbine section via a clutch; and a sensor monitoring a lubricant pressure within the primary lubricant supply circuit; wherein the clutch is activated to engage the auxiliary supply pump and the low pressure shaft of the turbine engine when the lubricant pressure within the primary lubricant supply circuit falls below a predetermined lubricant threshold.

[0073] The turbine engine of any preceding clause, wherein the lubrication system further comprises a heat exchanger configured to adjust a temperature of the lubricant circulating through the turbine engine.

[0074] The turbine engine of any preceding clause, further comprising a shuttle valve fluidly coupled to the heat exchanger, the primary supply pump, and the auxiliary supply pump.

[0075] The turbine engine of any preceding clause, wherein the auxiliary supply pump is a bi-directional pump.

[0076] The turbine engine of any preceding clause, further comprising a plurality of check valves positioned to allow the lubricant to flow unidirectionally through the primary lubricant supply circuit and the auxiliary lubricant supply circuit.

[0077] The turbine engine of any preceding clause, wherein, when the turbine engine is powered on, the primary lubricant supply circuit is activated such that the primary supply pump is powered by the high pressure shaft and the auxiliary lubricant supply circuit is decoupled from the low pressure shaft via the clutch.

[0078] The turbine engine of any preceding clause, wherein, when the turbine engine is powered off, the primary lubricant supply circuit is deactivated and the auxiliary lubricant supply circuit is activated such that the clutch engages the auxiliary supply pump and the low pressure shaft and the auxiliary supply pump is powered by the low pressure shaft.

[0079] A method of supplying lubricant to a gearbox assembly of a turbine engine, comprising: powering on the turbine engine such that the turbine engine enters a normal operating mode; activating a primary lubricant supply circuit of a lubrication system of the turbine engine; circulating lubricant from a reservoir positioned within the turbine engine through the primary lubricant supply circuit via a primary supply pump of the primary lubricant supply circuit such that the lubricant passes through the gearbox assembly and back to the reservoir; powering off the turbine engine such that the turbine engine enters a windmill operating mode and the primary lubricant supply circuit is deactivated; activating an auxiliary lubricant supply circuit of the lubrication system of the turbine engine; and circulating the lubricant from the reservoir through the auxiliary lubricant supply circuit via an auxiliary supply pump of the auxiliary lubricant supply circuit such that the lubricant passes through the gearbox and back to the reservoir.

[0080] The method of any preceding clause, wherein the method steps of circulating the lubricant through the primary lubricant supply circuit or circulating the lubricant through the auxiliary lubricant supply circuit further comprise circulating the lubricant through a heat exchanger to adjust a temperature of the lubricant prior to circulating the lubricant through the gearbox assembly.

[0081] The method of any preceding clause, further comprising monitoring a lubricant pressure of the lubricant circulating through the primary lubricant supply circuit via a pressure sensor; and activating the auxiliary lubricant supply circuit when the lubricant pressure falls below a predetermined lubricant threshold.

[0082] The method of any preceding clause, further comprising operating a shuttle valve to allow the lubricant to pass through the heat exchanger when the temperature of the lubricant exceeds a predetermined temperature threshold.

[0083] The method of any preceding paragraph, further comprising operating the shuttle valve to bypass the heat exchanger with the lubricant when the temperature of the lubricant is below the predetermined temperature threshold.

[0084] The method of any preceding paragraph, further comprising operating a plurality of check valves to allow one-way flow of the lubricant through the primary lubricant supply circuit and the auxiliary lubricant supply circuit.

[0085] The method of any preceding paragraph, further comprising activating the primary lubricant supply circuit and deactivating the auxiliary lubricant supply circuit upon power-up of the turbine engine.

[0086] Those skilled in the art will appreciate that various modifications and changes can be made to the embodiments described herein without departing from the scope of the claimed subject matter. Accordingly, it is intended that the specification be considered as exemplary only with the true scope of the embodiments described herein being indicated by the following claims and their equivalents.

Claims

1. A lubrication system for a turbine engine, characterized in that, comprising: a reservoir configured to store a lubricant; a primary lubricant supply circuit comprising a primary supply pump fluidly coupled to the reservoir; an auxiliary lubricant supply circuit comprising an auxiliary supply pump fluidly coupled to the reservoir; a clutch mechanically coupled to the auxiliary supply pump, the clutch configured to engage the auxiliary supply pump and a shaft of the turbine engine when activated; and a sensor monitoring a lubricant pressure within the primary lubricant supply circuit; wherein, when the lubricant pressure within the primary lubricant supply circuit falls below a predetermined lubricant threshold, the clutch is activated to engage the auxiliary supply pump and the shaft of the turbine engine.

2. The lubrication system of claim 1, wherein, further comprising a heat exchanger configured to adjust a temperature of the lubricant circulating through the turbine engine.

3. The lubrication system of claim 2, wherein, further comprising a shuttle valve fluidly coupled to the heat exchanger, the primary supply pump, and the auxiliary supply pump.

4. The lubrication system of claim 3, wherein, wherein, when the temperature of the lubricant exceeds a predetermined temperature threshold, the shuttle valve is operable to allow the lubricant to pass through the heat exchanger.

5. The lubrication system of claim 4, wherein, wherein, when the temperature of the lubricant is below the predetermined temperature threshold, the shuttle valve is operable to bypass the lubricant around the heat exchanger.

6. The lubrication system of claim 1, wherein, wherein, the auxiliary supply pump is a bi-directional pump.

7. The lubrication system of claim 1, wherein, further comprising a plurality of check valves operable to allow the lubricant to flow unidirectionally through the primary lubricant supply circuit and the auxiliary lubricant supply circuit.

8. The lubrication system of claim 1, wherein, wherein, when the turbine engine is powered on, the primary lubricant supply circuit is activated and the auxiliary lubricant supply circuit is deactivated.

9. The lubrication system of claim 1, wherein, wherein, when the turbine engine is powered off, the primary lubricant supply circuit is deactivated and the auxiliary lubricant supply circuit is activated.

10. The lubrication system of claim 1, wherein, wherein, the primary supply pump is mechanically coupled to an accessory gear box of the turbine engine such that rotation of the accessory gear box is configured to power the primary supply pump.

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