Gearbox assembly with gear brake system

Abstract

A gearbox assembly includes a gear assembly, an input shaft, an output shaft, and a gear brake system. The input shaft is coupled to the gear assembly. The output shaft is drivingly coupled to the input shaft through a gear assembly. A gear braking system is disposed within the gear assembly and includes one or more braking devices. The gear brake system actuates one or more brake devices to brake the gear assembly during a reverse torque state of the gearbox assembly.

Description

Technical Field

[0001] The present disclosure relates generally to gearbox assemblies and, in particular, to gear braking systems for gearbox assemblies. Background Art

[0002] A gearbox assembly, such as that of a vehicle, transfers torque from an input shaft to an output shaft. Such a vehicle may include a turbine engine, which typically includes a propeller (e.g., a fan or propeller) and a turbocharger (e.g., a compressor section, a combustion section, and a turbine section) arranged in flow communication with each other. The gearbox assembly in the turbine engine transfers torque and power from the turbocharger to the propeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The foregoing and other features and advantages will be apparent from the following more particular description of various exemplary embodiments, as illustrated in the drawings, in which like reference numerals generally indicate identical, functionally similar, or structurally similar elements.

[0004] Figure 1 is a schematic cross-sectional view of a turbine engine according to the present disclosure, taken along its longitudinal centerline axis.

[0005] Figure 2A A diagram of a gear brake system according to the present disclosure taken along section line 2A-2A and having the gear brake system in an unactuated state Figure 1 A schematic partial cross-sectional view of a gearbox assembly of a turbine engine.

[0006] Figure 2B is a schematic partial cross-sectional view of a gearbox assembly having a gear braking system in an actuated state according to the present disclosure.

[0007] Figure 2C According to the present disclosure Figure 1 Schematic cross-sectional view of a gearbox assembly with a gear brake system in an actuated state, taken at detail 2C in FIG.

[0008] Figure 3 is a schematic cross-sectional view of a gearbox assembly with a gear braking system in an actuated state according to another embodiment. DETAILED DESCRIPTION

[0009] Features, advantages, and embodiments of the present disclosure are set forth or apparent by considering the following detailed description, drawings, and claims. Furthermore, the following detailed description is exemplary and is intended to provide further explanation without limiting the scope of the disclosure as claimed.

[0010] Various embodiments of the present disclosure are discussed in detail below. Although specific embodiments are discussed, this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure.

[0011] As used herein, the terms “first,” “second,” “third,” and “fourth” may be used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of each component.

[0012] The terms "upstream" and "downstream" refer to relative directions of fluid flow in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction toward which the fluid is flowing.

[0013] The terms "fore" and "aft" refer to relative positions within a turbine engine or vehicle and refer to the normal operating attitude of the turbine engine or vehicle. For example, with respect to a high-bypass turbine engine, the front position refers to a position closer to the engine inlet, while the aft position refers to a position closer to the engine nozzle or exhaust. In one example, in a reverse-flow turbine engine, the front position refers to a position closer to the engine nozzle or exhaust, while the aft position refers to a position closer to the engine inlet.

[0014] Unless otherwise indicated herein, the terms "coupled," "fixed," "attached," "connected," and the like refer to both direct coupling, fixing, attachment, or connection as well as indirect coupling, fixing, attachment, or connection through one or more intermediate components or features.

[0015] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0016] As used herein, the terms "axial" and "axially" refer to directions and orientations extending generally parallel to the centerline of a turbine engine. Furthermore, the terms "radial" and "radially" refer to directions and orientations extending generally perpendicular to the centerline of a turbine engine. Furthermore, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending in an arc about the centerline of a turbine engine.

[0017] As used herein, a "propeller" is a component of a turbine engine that is drivingly coupled to a turbocharger engine so that rotation of the turbocharger engine component causes the propeller to rotate and generate thrust. A propeller may include a fan or a propeller. In a turbofan engine (ducted or non-ducted), the propeller is a fan. In a turboprop engine, the propeller is a propeller.

[0018] As used herein, "rigidity" or "stiffness" refers to the degree to which an object resists deformation in response to a force applied to the object. The more rigid an object is (e.g., the greater the stiffness), the less flexible the object is, and the greater the object's ability to resist deformation in response to a force applied to the object (e.g., the object does not bend or deform under the applied force). Similarly, the less rigid an object is (e.g., the less stiffness), the more flexible the object is, and the less capable the object is of resisting deformation in response to a force applied to the object (e.g., the object bends or deforms under the applied force).

[0019] As used herein, "normal operation" of a gearbox assembly, turbine engine, or vehicle refers to when the gearbox assembly, turbine engine, or vehicle is operating and torque is transferred from the input shaft to the output shaft through the gear assembly of the gearbox assembly in the operating torque direction. This causes the output shaft to rotate in the operating rotational direction. In the case of a turbine engine, during normal operation of the turbine engine, torque is transferred from the turbocharger (e.g., via the low-pressure shaft) to the propeller (e.g., via the propeller shaft) through the gear assembly.

[0020] As used herein, a "reverse torque condition" refers to when the torque through the gear assembly changes direction from the operating torque direction. In one example, a reverse torque condition occurs when torque is transferred from the output shaft to the input shaft through the gear assembly in a reverse torque direction that is opposite to the operating torque direction. In another example, a reverse torque condition occurs when the output shaft is operating in the operating direction of rotation, and torque is transferred from the output shaft through the gear assembly, causing the output shaft to slow down. A reverse torque condition may occur when the gearbox assembly, turbine engine, or vehicle is operating or shut down. In the case of a turbine engine, a reverse torque condition may occur when the propeller windmill turns and causes the propeller shaft to rotate, thereby rotating the gears of the gearbox assembly.

[0021] As used herein, "windmilling" or "windmilling" is a condition when the propeller and low-pressure shaft of a turbine engine continue to rotate at a low speed, while the high-pressure shaft rotates slowly or even stops. Windmilling may occur when the turbine engine is shut down but air is still flowing through the propeller (e.g., during an in-flight engine shutdown), or when the turbine engine is on the ground and the propeller rotates in the presence of wind while the turbine engine is shut down. During windmilling, torque is transferred from the propeller (e.g., via the propeller shaft) to the turbocharger engine (e.g., via the low-pressure shaft) through the gear assembly, so that the force (e.g., torque) is directed in a direction opposite to the direction of the operating torque.

[0022] As used herein throughout the specification and claims, approximating language is applied to modify any quantitative expression that can be permitted to vary without resulting in a change in the basic function to which it is related. Thus, values modified by terms such as "about," "approximately," "roughly," and "substantially" are not limited to the precise values specified. In at least some cases, approximating language can correspond to the precision of an instrument used to measure a value, or the precision of a method or machine used to construct or manufacture a component or system. For example, approximating language can refer to within one percent, two percent, four percent, ten percent, fifteen percent, or twenty percent of a single value, a range of values, or an endpoint of a defined range of values.

[0023] The present disclosure provides a gearbox assembly for a vehicle having one or more bearings. During operation, the gearbox assembly transmits torque from an input shaft to an output shaft via a gear assembly. In one embodiment, the gearbox assembly is used in a turbine engine, wherein the input shaft is a low-pressure shaft of a turbocharger of the turbine engine, and the output shaft is a propeller shaft of the turbine engine. In this manner, the turbocharger transmits torque to the propeller shaft via the gearbox assembly, thereby rotating the turbine engine's propeller.

[0024] The bearings allow for rotation of one or more gears of the gearbox assembly about the bearings. In one embodiment, one or more of the bearings are journal bearings. The bearings may include any type of bearing, such as roller bearings, ball bearings, etc. The bearings, and particularly the journal bearings, are hydrodynamic bearings that typically require a steady supply of lubricant during all phases of operation of the gearbox assembly to properly lubricate the bearings and thereby prevent damage due to sliding contact of the hydrodynamic journal bearings or even ordinary gear meshing interfaces. Typically, a lubrication system supplies lubricant to the bearings during operation of the gearbox assembly (e.g., when the turbine engine or vehicle is powered on and operating).

[0025] After the turbine engine is shut down, the input shaft or output shaft of the gearbox assembly may experience a long period of continuous rotation. For example, when the gearbox assembly is shut down, torque may be transferred from the output shaft to the input shaft in a reverse torque state. In one embodiment, this reverse torque state occurs when the propeller of the turbine engine is windmilling. In this case, the bearings may be affected by not receiving enough lubricant to lubricate the bearings. For example, during the reverse torque state (e.g., windmilling), the rotational speed of the shaft may be too low to power the pump that pumps lubricant to the bearings. In some cases, such as during operation of a vehicle (e.g., when the aircraft's turbine engine is in flight), the lubrication system may lose pressure (e.g., due to a failure of a pump or other component of the lubrication system), rendering the lubrication system unable to provide lubricant to the bearings.

[0026] The severity of lubrication interruption increases when the bearing is a journal bearing, as a lack of lubricant at the journal bearing can lead to journal bearing failure and subsequent gearbox failure, which can cause the input shaft (e.g., the low-pressure shaft) to permanently lock. This failure of the journal bearing is known as journal bearing seizure and occurs when contact occurs between a pin and a bore of one of the gears in the gear assembly, causing a significant increase in wear and friction that can lead to bearing failure. If contact occurs between the journal bearing and the pin during high-power operation, the two components can weld together due to the high temperatures generated by the friction.

[0027] Some gearbox assemblies include an auxiliary lubrication system that includes an auxiliary pump that supplies lubricant to the bearings to prevent damage to the bearings due to insufficient lubricant supply during reverse torque conditions. However, such an auxiliary lubrication system requires an increased complexity in driving the auxiliary pump. In addition, the auxiliary pump requires increased complexity to provide lubricant during high speeds, such as during operation of the gearbox assembly (e.g., a turbine engine or carrier) and during low speeds, such as during reverse torque conditions (e.g., during windmill rotation). During the reverse torque condition, the propeller may rotate in a reverse torque rotational direction that is opposite to the operating rotational direction of the gearbox assembly. This significantly increases the complexity of the auxiliary pump because the auxiliary pump needs to operate over a large speed range and provide a flow of lubricant regardless of the rotational direction of the output shaft (e.g., propeller).

[0028] Therefore, the present disclosure provides a gear braking system that brakes one or more of the gears of a gear assembly to prevent the gears from rotating, thereby preventing the output shaft (e.g., and the propeller) from rotating. The gear braking system actuates to brake (e.g., lock) the gears in response to a reverse torque state (e.g., the output shaft transfers torque to the input shaft). The gear braking system includes one or more braking devices (such as brake pads, etc.), and a brake fluid reservoir in which brake fluid is stored. The brake fluid reservoir is disposed within at least one of the gears, and in particular, within a pin of the gear. The pin includes a variable stiffness such that a first side of the pin has a greater stiffness than a second side of the pin. For example, the first side of the pin is the side on which an operational load is applied to the pin (e.g., a load from the gear when the gearbox assembly is operating during normal operation). Therefore, the brake fluid reservoir is disposed within the pin on the second side of the pin.

[0029] The gear braking system passively actuates the braking device during a reverse torque state. For example, the reverse torque state causes the gear to apply a reverse torque state load on the second side (rather than the first side). This reverse torque state load causes the pin to deform at the second side, causing the pin to squeeze the brake fluid reservoir and force the brake fluid out of the brake fluid reservoir. The brake fluid actuates the braking device so that the braking device contacts one or more of the gears and applies friction thereon to brake the gears and prevent the gears from rotating. During the reverse torque state, the output shaft transmits torque and power at a lower amplitude (e.g., approximately 150 horsepower) than the torque and power during normal operation. Therefore, the torque during the reverse torque state is relatively low relative to the torque during normal operation, and the braking device is able to brake the gears during the reverse torque state. The gear braking system is a closed brake fluid circuit so that when the braking device is not actuated, the brake fluid is recirculated back to the brake fluid reservoir.

[0030] Thus, the gear braking system of the present disclosure brakes or locks the gears to prevent the gears from rotating. In the event that the gears are not rotating, the bearings do not require lubricant. Thus, the gear braking system prevents the bearings from seizing during reverse torque conditions without having to supply lubricant to the bearings during reverse torque conditions. Thus, the gear braking system of the present disclosure eliminates the need for an auxiliary lubrication system and reduces the complexity of the lubrication system compared to a gearbox assembly without the benefit of the present disclosure. Furthermore, the closed brake fluid circuit placed within a single component (e.g., within a pin) reduces the likelihood of leakage compared to a braking system without the benefit of the present disclosure.

[0031] Referring now to the accompanying drawings, Figure 1 is a schematic cross-sectional view of a turbine engine 10 taken along a longitudinal centerline axis 12 of the turbine engine 10 according to an embodiment of the present disclosure. Figure 1 As shown, the turbine engine 10 defines an axial direction A extending parallel to the longitudinal centerline axis 12 , a radial direction R perpendicular to the axial direction A, and a circumferential direction C extending arcuately about the longitudinal centerline axis 12 .

[0032] Generally, the turbine engine 10 includes a propeller section 14 and a turbocharger 16 disposed downstream of the propeller section 14. The turbocharger 16 includes a compressor section 21, a combustor 26, and a turbine section 27 in series flow relationship. The turbocharger 16 is substantially enclosed within a casing 18 that is substantially tubular and defines a core inlet 20 that is annular about the longitudinal centerline axis 12. Figure 1As schematically shown in FIG, compressor section 21 includes a supercharger or low-pressure (LP) compressor 22, followed downstream by a high-pressure (HP) compressor 24. Combustor 26 is downstream of compressor section 21. Turbine section 27 is downstream of combustor 26 and includes a high-pressure (HP) turbine 28, followed downstream by a low-pressure (LP) turbine 30. Turbocharged engine 16 also includes an exhaust nozzle section 32, a high-pressure (HP) shaft 34, and a low-pressure (LP) shaft 36 downstream of turbine section 27. HP shaft 34 drivingly connects HP turbine 28 to HP compressor 24, and HP compressor 24, HP turbine 28, and HP shaft 34 are collectively referred to as the HP spool. HP turbine 28 and HP compressor 24 rotate in unison via HP shaft 34. LP shaft 36 drivingly connects LP turbine 30 to LP compressor 22, and LP compressor 22, LP turbine 30, and LP shaft 36 are collectively referred to as the LP spool. LP turbine 30 and LP compressor 22 rotate in unison via LP shaft 36. The compressor section 21 , the combustor 26 , the turbine section 27 , and the exhaust gas injection nozzle section 32 together define a core air flow path.

[0033] for Figure 1 In the embodiment depicted in FIG, the propeller section 14 includes a propeller 38 (eg, a variable pitch propeller) having a plurality of propeller blades 40 coupled to a disk 42 in a spaced apart manner. Figure 1 In some embodiments, the propeller 38 is a fan driven by the turbocharger engine 16. In some embodiments, the propeller 38 is a propeller driven by the turbocharger engine 16. The propeller blades 40 extend outwardly from the disk 42 generally along a radial direction R. In the case of a variable pitch propeller, a plurality of propeller blades 40 are rotatable about a pitch axis P relative to the disk 42 by means of the propeller blades 40 being operably coupled to an actuating member 44, the actuating member 44 being configured to collectively and uniformly vary the pitch of the propeller blades 40. The propeller blades 40, disk 42, and actuating member 44 together are rotatable about the longitudinal centerline axis 12 via a propeller shaft 45, which is powered by the LP shaft 36 across a power gearbox, also referred to as a gearbox assembly 46 (e.g., where the turbine engine 10 is an indirect drive engine). In this manner, the propeller 38 is drivingly coupled to the turbocharger engine 16 and is powered by the turbocharger engine 16. The gearbox assembly 46 is at Figure 1 The gearbox assembly 46 is a speed reduction gearbox assembly for adjusting the rotational speed of the propeller shaft 45 when power is transferred from the LP shaft 36 to the propeller shaft 45 , and thus adjusting the rotational speed of the propeller 38 relative to the LP shaft 36 .

[0034] Still refer to Figure 1In the exemplary embodiment of the present invention, the disk 42 is covered by a propeller hub 48 that is aerodynamically shaped to facilitate airflow through the plurality of propeller blades 40. In addition, the propeller section 14 includes an annular casing or nacelle 50 that circumferentially surrounds the propeller 38 and at least a portion of the turbocharger engine 16. The nacelle 50 is supported relative to the turbocharger engine 16 by a plurality of outlet guide vanes 52 that are circumferentially spaced about the nacelle 50 and the turbocharger engine 16. Furthermore, a downstream section 54 of the nacelle 50 extends over an outer portion of the turbocharger engine 16 and, together with the outer casing 18, defines a bypass airflow passage 56 therebetween.

[0035] During operation of turbine engine 10, a volume of air 58 enters turbine engine 10 through an inlet 60 of nacelle 50 or propeller section 14. As air 58 passes through propeller blades 40, a first portion of the air (also referred to as bypass air 62) is directed into bypass airflow passage 56. Simultaneously, a second portion of the air (also referred to as core air 64) is directed into an upstream section of the core air flow path through core inlet 20 of LP compressor 22. The ratio between bypass air 62 and core air 64 is generally referred to as the bypass ratio. The pressure of core air 64 is then increased by LP compressor 22, thereby generating compressed air 65. Compressed air 65 is directed through HP compressor 24, where its pressure is further increased. Compressed air 65 is then directed into combustor 26, where it is mixed with fuel and ignited to generate combustion gases 66.

[0036] The combustion gases 66 are directed into the HP turbine 28 and expanded therethrough, where a portion of the thermal or kinetic energy from the combustion gases 66 is extracted via one or more stages of HP turbine stator blades 68 and HP turbine rotor blades 70 coupled to the HP shaft 34. This causes the HP shaft 34 to rotate, thereby supporting the operation of the HP compressor 24 via the HP shaft 34 (a self-sustaining cycle). In this manner, the combustion gases 66 act on the HP turbine 28. The combustion gases 66 are then directed into the LP turbine 30 and expanded therethrough. Here, a second portion of the thermal or kinetic energy is extracted from the combustion gases 66 via one or more stages of LP turbine rotor blades 74 and LP turbine stator blades 72 coupled to the LP shaft 36. This causes the LP shaft 36 to rotate, thereby supporting the operation of the LP compressor 22 (a self-sustaining cycle) and the rotation of the propeller 38 via the gearbox assembly 46 via the LP shaft 36. In this manner, the combustion gases 66 act on the LP turbine 30.

[0037] The combustion gases 66 are then directed through the jet exhaust nozzle section 32 of the turbocharger engine 16 to provide propulsive thrust. Simultaneously, the bypass air 62 is directed through the bypass flow passage 56 before being discharged from the propulsor 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 turbocharger engine 16.

[0038] Figure 1 The turbine engine 10 depicted in FIG. 1 is provided as an example only. In other exemplary embodiments, the turbine engine 10 may have any other suitable configuration. For example, in other exemplary embodiments, the propeller 38 may be configured in any other suitable manner (e.g., as a fixed-pitch propeller) and may also be supported using any other suitable propeller frame configuration. Furthermore, in other exemplary embodiments, any other suitable number or configuration of compressors, turbines, shafts, or combinations thereof may be provided. In still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable turbine engine (e.g., a turbofan, propfan, turbojet, turboprop, or turboshaft).

[0039] Figure 2A According to the present disclosure Figure 1 2A-2A and having the gear brake system 200 in an unactuated state. Figure 2B is a schematic partial cross-sectional view of a gearbox assembly 46 with a gear braking system 200 in an actuated state according to the present disclosure. Figure 2C According to the present disclosure Figure 1 Schematic cross-sectional view of the gearbox assembly 46 taken at detail 2C in FIG. 4 and having the gear brake system 200 in an actuated state.

[0040] The gearbox assembly 46 includes a gear assembly 100, an input shaft 101 ( Figure 2C ) and output shaft 103( Figure 2C ). The output shaft 103 is drivingly coupled to the input shaft 101 through the gear assembly 100. Figures 1 to 2C In the embodiment of the present invention, the input shaft 101 is the LP shaft 36 ( Figure 1 ), and the output shaft 103 is the propeller shaft 45 ( Figure 1 ), so that the turbocharged engine 16 ( Figure 1 ) drives the propeller 38 through the gearbox assembly 46 ( Figure 1), as described above. In some embodiments, the gearbox assembly 46 can be used in applications other than turbine engines (e.g., in an automobile, etc.). In such applications, the input shaft 101 can be coupled to the crankshaft of the automobile (e.g., via a flywheel therebetween), and the output shaft 103 can be a shaft of the automobile's transmission for providing power to the wheels of the automobile through the gearbox assembly.

[0041] The gear assembly 100 includes a plurality of gears 102, 104, and 106. The plurality of gears 102, 104, and 106 include a first gear 102, a second gear 104, and a third gear 106. Figures 2A to 2C In the embodiment, the first gear 102 is a sun gear, the second gear 104 is a planetary gear, and the third gear 106 is a ring gear. Figures 2A to 2C 104 and 106, but the gear assembly 100 may include one or more first gears 104, one or more second gears 104 and one or more third gears 106. The second gear 104 is supported by a second gear carrier 105 ( Figure 2C )constraint.

[0042] The gear assembly 100 can be arranged as an epicyclic gear assembly. When the gear assembly 100 is an epicyclic gear assembly, the gear assembly 100 includes a plurality of second gears 104 (e.g., two or more second gears 104). In an epicyclic gear assembly, the gear assembly 100 can be a star-shaped gear assembly or a rotating ring gear type gear assembly (e.g., the third gear 106 rotates about the longitudinal centerline axis 12, while the second gear carrier 105 is fixed and stationary). In this arrangement, the output shaft 103 is driven by the third gear 106. For example, the third gear 106 is coupled to the propeller shaft 45 ( Figure 1 ), such that rotation of the third gear 106 causes rotation of the propeller shaft 45 and, therefore, of the propeller 38. In this manner, the third gear 106 is the output of the gear assembly 100. However, other suitable types of gear assemblies may be employed. In one non-limiting embodiment, the gear assembly 100 is a planetary arrangement in which the third gear 106 is held stationary and the second gear carrier 105 ( Figure 2C) are allowed to rotate. In this arrangement, the output shaft 103 is driven by the second gear carrier 105. For example, the second gear carrier 105 is coupled to the propeller shaft 45 such that rotation of the second gear carrier 105 causes the propeller shaft 45 to rotate, and therefore causes the propeller 38 to rotate. In this manner, the second gear 104 (e.g., via the second gear carrier 105) is the output of the gear assembly 100. In another non-limiting embodiment, the gear assembly 100 can be a differential gear assembly in which both the third gear 106 and the second gear carrier 105 are allowed to rotate. Although an epicyclic gear assembly is described in detail herein, the gear assembly 100 can include any type of gear assembly, including, for example, a compound gear assembly, a multi-stage gear assembly, etc.

[0043] The first gear 102 includes a plurality of first gear teeth 108 ( Figure 2A and Figure 2B A plurality of first gear teeth 108 are provided on the outer surface of the first gear 102. The second gear 104 includes a plurality of second gear teeth 110 ( Figure 2A and Figure 2B A plurality of second gear teeth 110 are provided on the outer surface of the second gear 104. The third gear 106 includes a plurality of third gear teeth 112 ( Figure 2A and Figure 2B Only one is shown in the figure). A plurality of third gear teeth 112 are disposed on an interior surface of the third gear 106. The plurality of first gear teeth 108, the plurality of second gear teeth 110, and the plurality of third gear teeth 112 may include spur gear teeth (e.g., gear teeth extending substantially parallel to the gear longitudinal centerline axis of the respective gears), helical gear teeth (e.g., gear teeth extending at a non-zero angle relative to the gear longitudinal centerline axis), etc.

[0044] The first gear 102 is coupled to the input shaft 101 of the gearbox assembly 46 ( Figure 2C ), so that the rotation of the input shaft 101 causes the first gear 102 to rotate. In particular, the first gear 102 is coupled to the LP shaft 36 ( Figure 1 ), such that rotation of the LP shaft 36 causes rotation of the first gear 102. Radially outwardly of the first gear 102 and intermeshing therewith is a second gear 104 supported by a second gear carrier 105. In particular, a plurality of second gear teeth 110 intermesh with a plurality of first gear teeth 108. The second gear carrier 105 supports and constrains the second gear 104 so that the second gear 104 can rotate about a second gear longitudinal centerline axis 107 ( Figure 2C) rotates, but does not rotate around the periphery of the first gear 102. Radially outwardly of the second gear 104 and meshing therewith is a third gear 106, which is an annular ring gear. In particular, a plurality of third gear teeth 112 mesh with a plurality of second gear teeth 110. The third gear 106 is connected to the output shaft 103 ( Figure 2C ) is coupled and rotated to drive the output shaft 103 to rotate about the longitudinal centerline axis 12. In particular, the third gear 106 is connected to the propeller shaft 45 ( Figure 1 ) is connected to the propeller 38 ( Figure 1 ) and rotates to drive the propeller 38 to rotate about the longitudinal centerline axis 12.

[0045] The second gear 104 includes a second gear pin 120, and the second gear 104 rotates about the second gear pin 120. In particular, the second gear pin 120 is disposed within the second gear 104, and the second gear 104 rotates relative to the second gear pin 120. The second gear pin 120 is hollow and defines a hollow interior 122. The second gear pin 120 is coupled to the second gear carrier 105 ( Figure 2C ) is coupled so that the second gear pin 120 is a static component and is prevented from rotating about the second gear longitudinal centerline axis 107 ( Figure 2C ) rotates. In this way, the second gear 104 is constrained by the second gear carrier 105.

[0046] The second gear 104 includes one or more second gear bearings 130 disposed therein. The one or more second gear bearings 130 enable the second gear 104 to rotate about the one or more second gear bearings 130 so that the second gear 104 rotates about the second gear longitudinal centerline axis 107 ( Figure 2C ) rotates. The one or more second gear bearings 130 may include any type of bearing for a gear, such as a journal bearing, a roller bearing, etc. Figures 2A to 2C In an embodiment, the one or more second gear bearings 130 include a journal bearing defined between the second gear pin 120 and the second gear 104. For example, a lubricant (e.g., oil) is provided between the second gear pin 120 and the second gear 104 such that a lubricant film is formed between the outer surface of the second gear pin 120 and the inner surface of the second gear 104. The lubricant film maintains a space or gap between the second gear 104 and the second gear pin 120, allowing the second gear 104 to rotate relative to the second gear pin 120.

[0047] When Figure 2A and Figure 2BWhen viewed in the orientation of the second gear 104 and the second gear pin 120, the second gear 104 and the second gear pin 120 can be viewed with respect to a "clock" orientation having a twelve o'clock position, a three o'clock position, a six o'clock position, and a nine o'clock position. Although no reference numbers are provided, the clock orientations are understood to include all clock positions therebetween. The twelve o'clock position is positioned at the top of the second gear 104 and the second gear pin 120, the three o'clock position is positioned ninety degrees (90°) from the twelve o'clock position, the six o'clock position is positioned at the bottom of the second gear 104 and the second gear pin 120 and is one hundred and eighty degrees (180°) from the twelve o'clock position, and the nine o'clock position is positioned ninety degrees (90°) from the six o'clock position.

[0048] The second gear pin 120 includes a rigid portion 124 and a deformable portion 126. The rigid portion 124 has a greater stiffness than the deformable portion and resists deformation when an operational load is applied to the second gear pin 120 during normal operation of the gearbox assembly 46 (e.g., during normal operation of the turbine engine 10), as described in further detail below. The deformable portion 126 has a lesser stiffness than the rigid portion 124 and deforms when a reverse torque load is applied to the second gear pin 120 during a reverse torque condition of the gearbox assembly 46, as described in further detail below. For example, the deformable portion 126 can have a smaller thickness than the rigid portion 124. In some embodiments, the deformable portion 126 is made of a material having a lesser stiffness than the material of the rigid portion 124. For example, the deformable portion 126 can be made of a material having a lesser elastic modulus than the material of the rigid portion 124 of the second gear pin 120.

[0049] A rigid portion 124 is defined on a first side of the second gear pin 120, and a deformable portion 126 is defined on a second side of the second gear pin 120, opposite the first side. Specifically, the rigid portion 124 is defined between the six o'clock and twelve o'clock positions of the second gear pin 120 in a clockwise direction. The deformable portion 126 is defined between the twelve o'clock and six o'clock positions of the second gear pin 120 in a clockwise direction. In this manner, the rigid portion 124 is positioned approximately at the nine o'clock position, while the deformable portion 126 is positioned approximately at the three o'clock position. In some embodiments, the deformable portion 126 may include a gradient stiffness, such that the stiffness of the second gear pin 120 decreases from the rigid portion 124 to the deformable portion 126. For example, the stiffness decreases from the twelve o'clock and six o'clock positions of the second gear pin 120 to the three o'clock position.

[0050] The gear brake system 200 includes one or more brake devices 202, a brake fluid reservoir 204, and one or more brake fluid lines 206. Figures 2A to 2CIn the embodiment, the one or more braking devices 202 are brake pads that apply friction to the second gear 104 when actuated to brake (e.g., lock) the second gear 104 to prevent the second gear 104 from rotating, as described in further detail below. The one or more braking devices 202 include a friction material that applies friction on the second gear 104 to brake the second gear 104. The friction material may include, for example, a rubber material, a ceramic material, a composite material, a metal material, etc. Figures 2A to 2C In an embodiment, the one or more braking devices 202 include a first braking device 202a and a second braking device 202b. The first braking device 202a is positioned approximately at the radially top portion of the second gear pin 120 (e.g., approximately at the 12 o'clock position of the second gear pin 120). The second braking device 202b is positioned approximately at the radially bottom portion of the second gear pin 120 (e.g., approximately at the 6 o'clock position of the second gear pin 120). The gear braking system 200 actuates the one or more braking devices 202 to contact the second gear 104 and prevent the second gear 104 from rotating, as described in further detail below.

[0051] The brake fluid reservoir 204 stores brake fluid 208 therein. The brake fluid is a hydraulic fluid, such as water, oil, mineral oil, glycol ether fluid, silicone-based fluid, etc. The brake fluid reservoir 204 is disposed within the second gear 104. In particular, the brake fluid reservoir 204 is disposed within the hollow interior 122 of the second gear pin 120. The brake fluid reservoir 204 is positioned within the second gear pin 120 approximately at the deformable portion 126 of the second gear pin 120. In particular, the brake fluid reservoir 204 is positioned between the twelve o'clock position and the six o'clock position in a clockwise direction (e.g., approximately at the three o'clock position). The brake fluid reservoir 204 is positioned within the second gear pin 120 such that the second gear pin 120 (deformable portion 126) contacts the brake fluid reservoir 204 during a reverse torque state, as described in further detail below. The brake fluid reservoir 204 is made of a deformable material and may include thin walls such that when the brake fluid reservoir is deformed, brake fluid is directed out of the brake fluid reservoir. The thin walls of the brake fluid reservoir 204 are in fluid communication with one or more brake fluid lines 206. In some embodiments, the gear brake system 200 includes one or more valves (e.g., check valves, etc.) in fluid communication with the brake fluid reservoir 204 and the one or more brake fluid lines 206 such that when the brake fluid reservoir 204 is deformed, brake fluid is directed through the one or more valves into the one or more brake fluid lines 206.

[0052] One or more brake fluid lines 206 are in fluid communication with one or more brake devices 202 and brake fluid reservoir 204. In this manner, one or more brake fluid lines 206 direct brake fluid from brake fluid reservoir 204 to one or more brake devices 202 to actuate one or more brake devices 202, as described in further detail below. One or more brake fluid lines 206 include a first brake fluid line 206a and a second brake fluid line 206b. First brake fluid line 206a is in fluid communication with first brake device 202a. Second brake fluid line 206b is in fluid communication with second brake device 202b.

[0053] In the gearbox assembly 46 (e.g., Figure 1 During normal operation of the gearbox assembly 46 of the turbine engine 10), the input shaft 101 ( Figure 2C ) rotates and transmits power to the output shaft 103 ( Figure 2C ). In particular, the LP axis 36 ( Figure 1 ) rotates and transmits power to the propeller shaft 45 ( Figure 1 ), to rotate the propeller 38 ( Figure 1 ), as mentioned above about Figure 1 Detailed. Reference Figure 2A During normal operation, the gear braking system 200 is deactivated, such that the one or more braking devices 202 are spaced apart from the second gear 104 and prevented from contacting the second gear 104 (e.g., the gear assembly 100 is not locked). This allows the plurality of gears 102, 104, and 106 of the gear assembly 100 to rotate during normal operation. The first gear 102 rotates in a first gear operating rotational direction 150. As the first gear 102 rotates, the plurality of first gear teeth 108 intermesh with the plurality of second gear teeth 110, thereby reacting against the plurality of first gear teeth 108. This results in torque being transferred from the first gear 102 to the second gear 104, thereby rotating the second gear 104 in a second gear operating rotational direction 152. The second gear operating rotational direction 152 is opposite the first gear operating rotational direction 150. Simultaneously, the plurality of second gear teeth 110 intermesh with the plurality of third gear teeth 112, thereby reacting against the plurality of third gear teeth 112.

[0054] In the star arrangement of the gear assembly 100, this results in torque being transferred from the second gear 104 to the third gear 106, thereby rotating the third gear 106 and the output shaft 103 ( Figure 2C For example, the third gear 106 rotates the propeller shaft 45 ( Figure 1 ), thereby making the propeller 38 ( Figure 1) rotates. In the planetary arrangement of the gear assembly 100, the second gear 104 rotates about the longitudinal centerline axis 12, and the third gear 106 is stationary, so that the third gear 106 applies a reaction torque to the second gear 104. In this way, the second gear 104 is rotated via the second gear carrier 105 ( Figure 2C ) rotates the output shaft 103. For example, the second gear 104 (via the second gear carrier 105) rotates the propeller shaft 45, thereby rotating the propeller 38.

[0055] The intermeshing of the plurality of second gear teeth 110 with the plurality of first gear teeth 108 and the plurality of third gear teeth 112 applies a gear tooth operating load 154 to the plurality of second gear teeth 110 in a first gear tooth load direction. As the second gear 104 rotates, the second gear 104 applies a second gear operating load 156 to the second gear pin 120. The second gear 104 applies the second gear operating load 156 to the rigid portion 124 of the second gear pin 120. The rigid portion 124 prevents the second gear pin 120 from deforming under the second gear operating load 156. Consequently, the second gear pin 120 is prevented from contacting the brake fluid reservoir 204 during normal operation. In this manner, the gear brake system 200 is prevented from actuating one or more brake devices 202 and braking the second gear 104, and thus the output shaft 103, during normal operation. For example, the LP shaft 36 rotates the propeller shaft 45 via the gearbox assembly 46, and torque is transmitted from the LP shaft 36 to the propeller shaft 45 to rotate the propeller 38 during normal operation.

[0056] refer to Figure 2B and Figure 2C During a reverse torque state (e.g., during windmill rotation), torque is transferred from the output shaft 103 ( Figure 2C ) is transmitted to the input shaft 101 ( Figure 2C For example, the windmill rotates to make the propeller 38 ( Figure 1 ) rotates, thereby rotating the output shaft 103 (e.g., propeller shaft 45). In this manner, torque is transmitted through the gearbox assembly 46 in the opposite direction to the direction of torque transmission during normal operation. To prevent the plurality of gears 102, 104, and 106 from rotating, the present disclosure provides a method of braking the gear assembly 100 by actuating one or more braking devices 202 during a reverse torque state to brake the gear assembly 100, as further described below. During the reverse torque state, the second gear 104 tends to rotate in a direction opposite to the second gear operating rotational direction 152 ( Figure 2A ) The second gear rotates in the opposite torque rotation direction 162.

[0057] The intermeshing of the plurality of second gear teeth 110 with the plurality of first gear teeth 108 and the plurality of third gear teeth 112 applies a gear tooth reverse torque load 164 to the plurality of second gear teeth 110 in a second gear tooth load direction opposite the first gear tooth load direction. When the second gear 104 tends to rotate, the second gear 104 applies a second gear reverse torque load 166 to the second gear pin 120. The second gear 104 applies the second gear reverse torque load 166 to the deformable portion 126 of the second gear pin 120. In this manner, the second gear pin 120 deforms under the second gear reverse torque load 166. In other words, the second gear 104 compresses the second gear pin 120 during the reverse torque state. Therefore, during the reverse torque state, the second gear pin 120 contacts the brake fluid reservoir 204 and applies a force to the brake fluid reservoir 204. This force causes the brake fluid reservoir 204 to deform, directing the brake fluid out of the brake fluid reservoir 204 and into one or more brake fluid lines 206. One or more brake fluid lines 206 direct brake fluid to one or more brake devices 202 to actuate the one or more brake devices 202 to contact the second gear 104. In this manner, the gear braking system 200 actuates the one or more brake devices 202 during the reverse torque state and brakes the second gear 104, and thereby brakes the output shaft 103, to prevent the output shaft 103 from rotating during the reverse torque state. Thus, the gear assembly 100 is braked and locked during the reverse torque state. Specifically, during the reverse torque state (e.g., when the propeller 38 is windmilling), torque is transmitted from the propeller 38 to the gear assembly 100 (e.g., the second gear 104) via the propeller shaft 45, and the gear braking system 200 actuates the one or more brake devices 202 to prevent the propeller shaft 45 from rotating (e.g., preventing the plurality of gears 102, 104, and 106 of the gear assembly 100 from rotating).

[0058] In embodiments including a plurality of second gears 104, one or more of the plurality of second gears 104 may include a corresponding gear braking system 200 disposed therein based on the braking force required for the particular gear assembly. Figures 2B to 2C In some embodiments, the one or more braking devices 202 move generally radially to contact the inner surface of the second gear 104, thereby braking (locking) the second gear 104 and preventing the second gear 104 from rotating. In some embodiments, the one or more braking devices 202 can move axially to brake (lock) the second gear 104, as described below with respect to Figure 3 Further details.

[0059] Figure 3is a schematic cross-sectional view of a gearbox assembly 46 having a gear brake system 300 in an actuated state according to another embodiment. The gear brake system 300 includes one or more brake devices 302, a brake fluid reservoir 304, and one or more brake fluid lines 306. The one or more brake devices 302, the brake fluid reservoir 304, and the one or more brake fluid lines 306 are substantially similar to Figures 2A to 2C The one or more brake devices 202, the brake fluid reservoir 204 and the one or more brake fluid lines 206. The one or more brake devices 302 include a first brake device 302a and a second brake device 302b. The first brake device 302a and the second brake device 302b are positioned to be actuated substantially axially when the gear brake system 300 is actuated. Figure 3 , first brake device 302a and second brake device 302b are positioned on the top portion of second gear pin 120. First brake device 302a is positioned at the axial front surface of second gear 104. Second brake device 302b is positioned at the axial rear surface of second gear 104. One or more brake fluid lines 306 include a first brake fluid line 306a and a second brake fluid line 306b. First brake fluid line 306a is in fluid communication with brake fluid reservoir 304 and first brake device 302a. Second brake fluid line 306b is in fluid communication with brake fluid reservoir 304 and second brake device 302b.

[0060] The one or more brake devices 302 may also include a third brake device 302c and a fourth brake device 302d. The third brake device 302c and the fourth brake device 302d are positioned to actuate substantially axially when the gear brake system 300 is actuated. Figure 3 , third brake device 302c and fourth brake device 302d are positioned on the bottom portion of second gear pin 120. Third brake device 302c is positioned at the axial front surface of second gear 104. Fourth brake device 302d is positioned at the axial rear surface of second gear 104. One or more brake fluid lines 306 also include a third brake fluid line 306c and a fourth brake fluid line 306d. Third brake fluid line 306c is in fluid communication with brake fluid reservoir 304 and third brake device 302c. Fourth brake fluid line 306d is in fluid communication with brake fluid reservoir and fourth brake device 302d.

[0061] The operation of the gear brake system 300 is substantially similar to the operation of the gear brake system 200 of FIG. 2 . However, when the gear brake system 300 is actuated (e.g., Figure 3 ), one or more brake devices 302 move substantially axially, rather than substantially radially (e.g. Figure 2C). Specifically, the first braking device 302a moves axially rearward to contact the second gear 104, and the second braking device 302b moves axially forward to contact the second gear 104. Similarly, the third braking device 302c moves axially rearward to contact the second gear 104, and the fourth braking device 302d moves axially forward to contact the second gear 104. In this manner, the one or more braking devices 302 are actuated to brake the second gear 104, and therefore the output shaft 103, to prevent the output shaft 103 from rotating during the reverse torque state. During normal operation, the one or more braking devices 302 are axially spaced from the second gear 104, so that the second gear 104 and, therefore, the output shaft 103 are allowed to rotate.

[0062] Thus, the gear braking systems 200 and 300 brake or lock the gears 102, 104, and 106 to prevent the gears 102, 104, and 106 from rotating during the reverse torque state. In the absence of rotation of the gears 102, 104, and 106, no lubricant is required for the second gear bearing 130 and the gears 102, 104, and 106. Thus, the gear braking systems 200 and 300 prevent the bearing of the second gear bearing 130 from seizing during the reverse torque state without having to supply lubricant to the second gear bearing 130 during the reverse torque state. Thus, the gear braking systems 200 and 300 eliminate the need for an auxiliary lubrication system and reduce the complexity of the lubrication system compared to a gearbox assembly without the benefit of the present disclosure. Furthermore, since there is no need to have a brake fluid line from outside the gear assembly, the closed brake fluid circuit placed within a single component (e.g., within the second gear 104) reduces the likelihood of leakage compared to a braking system without the benefit of the present disclosure.

[0063] Further aspects of the disclosure are provided by the subject matter of the following clauses.

[0064] A gearbox assembly comprises: a gear assembly; an input shaft coupled to the gear assembly; an output shaft drivingly coupled to the input shaft via the gear assembly; and a gear braking system disposed within the gear assembly and comprising one or more braking devices, the gear braking system actuating the one or more braking devices to brake the gear assembly during a reverse torque state of the gearbox assembly.

[0065] The gearbox assembly according to the preceding clause, wherein the reverse torque state is when torque is transferred from the output shaft to the input shaft through the gear assembly.

[0066] According to the gearbox assembly of any preceding clause, the gear braking system includes a brake fluid reservoir storing brake fluid therein, and the gear braking system supplies the brake fluid from the brake fluid reservoir to the one or more braking devices to actuate the one or more braking devices during the reverse torque state.

[0067] A gearbox assembly according to any preceding clause, wherein the gear braking system comprises one or more brake fluid lines in fluid communication with the brake fluid reservoir and the one or more braking devices, and wherein the brake fluid lines direct the brake fluid from the brake fluid reservoir to the one or more braking devices during the reverse torque state.

[0068] A gearbox assembly as claimed in any preceding clause, the gear assembly comprising a first gear and a second gear intermeshing with the first gear, and the brake fluid reservoir being disposed within the second gear.

[0069] A gearbox assembly according to any preceding clause, wherein the one or more braking devices are spaced apart from the second gear during normal operation of the gearbox assembly, and the gear braking system actuates the one or more braking devices during the reverse torque state so that the one or more braking devices contact the second gear to brake the gear assembly.

[0070] A gearbox assembly as described in any preceding clause, the second gear comprising a second gear pin, the second gear rotating about the second gear pin, and the brake fluid reservoir being disposed within the second gear pin.

[0071] The gearbox assembly of any preceding clause, wherein the second gear pin is deformable and deforms during the reverse torque state such that the second gear pin squeezes the brake fluid reservoir and forces the brake fluid out of the brake fluid reservoir to supply the brake fluid to the one or more braking devices.

[0072] A gearbox assembly as described in any preceding clause, the second gear pin including a deformable portion, and the brake fluid reservoir being positioned within the second gear pin at the deformable portion.

[0073] A gearbox assembly as claimed in any preceding clause, wherein the second gear pin comprises a rigid portion, and wherein the deformable portion has a stiffness less than that of the rigid portion.

[0074] A gearbox assembly as claimed in any preceding clause, the gear assembly comprising a plurality of gears, the plurality of gears comprising the first gear and the second gear.

[0075] A gearbox assembly as described in any preceding clause, the gear assembly comprising a third gear.

[0076] The gearbox assembly of the preceding clause, wherein the first gear is a sun gear, the second gear is a planet gear, and the third gear is a ring gear.

[0077] A gearbox assembly as claimed in any preceding clause, wherein the second gear is constrained by a second gear carrier.

[0078] A gearbox assembly as described in any preceding clause, the gear assembly comprising a plurality of second gears.

[0079] A gearbox assembly as described in any preceding clause, wherein the first gear comprises a first plurality of gear teeth.

[0080] A gearbox assembly as described in any preceding clause, wherein the second gear comprises a second plurality of gear teeth.

[0081] A gearbox assembly as described in any preceding clause, wherein the third gear comprises a third plurality of gear teeth.

[0082] A gearbox assembly as claimed in any preceding clause, wherein the second plurality of gear teeth intermesh with the first plurality of gear teeth.

[0083] A gearbox assembly as claimed in any preceding clause, wherein the third plurality of gear teeth intermesh with the second plurality of gear teeth.

[0084] A gearbox assembly as claimed in any preceding clause, the input shaft being coupled to the first gear.

[0085] A gearbox assembly as claimed in any preceding clause, wherein the output shaft is coupled to the third gear.

[0086] A gearbox assembly as claimed in any preceding clause, wherein the output shaft is coupled to the second carrier.

[0087] A gearbox assembly as claimed in any preceding clause, wherein the input shaft is a low pressure shaft of a turbocharger of a turbine engine.

[0088] A gearbox assembly as claimed in any preceding clause, wherein the output shaft is a propeller shaft of a propeller of the turbine engine.

[0089] The gearbox assembly of any preceding clause, the second gear comprising one or more second gear bearings disposed therein, the one or more second bearings permitting the second gear to rotate about a second gear longitudinal centerline axis.

[0090] A gearbox assembly as described in any preceding clause, wherein the one or more bearings are journal bearings.

[0091] A gearbox assembly as described in any preceding clause, wherein the journal bearing is defined between the second gear pin and the second gear.

[0092] A gearbox assembly as claimed in any preceding clause, wherein the second gear deforms and applies a reverse torque load during the reverse torque condition.

[0093] A gearbox assembly as described in any preceding clause, wherein the rigid portion is defined on a first side of the second gear pin.

[0094] A gearbox assembly as described in any preceding clause, wherein the deformable portion is defined on a second side of the second gear pin opposite the first side.

[0095] A gearbox assembly as claimed in any preceding clause, the first side being a side of the second gear pin on which the second gear exerts an operational load during normal operation of the gearbox assembly.

[0096] A gearbox assembly as claimed in any preceding clause, the second side being the side of the second gear pin on which the second gear exerts the reverse torque load during the reverse torque condition.

[0097] A gearbox assembly as claimed in any preceding clause, wherein the one or more braking devices are brake pads.

[0098] A gearbox assembly as claimed in any preceding clause, wherein the one or more braking devices apply friction to the second gear to brake the second gear.

[0099] A gearbox assembly as claimed in any preceding clause, wherein the one or more braking devices comprise a first braking device and a second braking device.

[0100] A gearbox assembly as claimed in any preceding clause, wherein the first braking device is positioned at a radially top portion of the second gear pin.

[0101] A gearbox assembly as claimed in any preceding clause, wherein the second braking device is positioned at a radial bottom portion of the second gear pin.

[0102] A gearbox assembly as claimed in any preceding clause, wherein said one or more braking devices move generally radially outwardly to contact said second gear during said reverse torque condition.

[0103] A gearbox assembly as claimed in any preceding clause, wherein the one or more braking devices move generally axially to contact the second gear during the reverse torque condition.

[0104] A gearbox assembly as claimed in any preceding clause, wherein the first braking device moves axially forward and the second braking device moves axially rearward to contact the second gear.

[0105] A gearbox assembly according to any preceding clause, wherein the one or more braking devices include a third braking device and a fourth braking device, the first braking device and the second braking device are positioned at the top portion of the second gear pin, and the third braking device and the fourth braking device are positioned at the bottom portion of the second gear pin.

[0106] A method of braking a gear assembly of a gearbox assembly, the gearbox assembly comprising an input shaft, an output shaft, and a gear braking system, the output shaft being drivingly coupled to the input shaft via the gear assembly, the gear braking system being disposed within the gear assembly and comprising one or more braking devices, the method comprising actuating the one or more braking devices to brake the gear assembly during a reverse torque state of the gearbox assembly.

[0107] A method as in any preceding clause, the reverse torque condition being when torque is transferred from the output shaft to the input shaft through the gear assembly.

[0108] A method according to any preceding clause, the gear brake system comprising a brake fluid reservoir storing brake fluid therein, and the method further comprising supplying the brake fluid from the brake fluid reservoir to the one or more brake devices to actuate the one or more brake devices during the reverse torque state.

[0109] A method according to any preceding clause, wherein the gear braking system comprises one or more brake fluid lines in fluid communication with the brake fluid reservoir and the one or more braking devices, and the method further comprises directing the brake fluid from the brake fluid reservoir to the one or more braking devices through the one or more brake fluid lines during the reverse torque state.

[0110] A method as defined in any preceding clause, wherein the gear assembly comprises a first gear and a second gear intermeshing with the first gear, and wherein the brake fluid reservoir is disposed within the second gear.

[0111] A method according to any preceding clause, wherein the one or more braking devices are spaced apart from the second gear during normal operation of the gearbox assembly, and the method further comprises actuating the one or more braking devices during the reverse torque state so that the one or more braking devices contact the second gear to brake the gear assembly.

[0112] A method as defined in any preceding clause, the second gear comprising a second gear pin, the second gear rotating about the second gear pin, and the brake fluid reservoir being disposed within the second gear pin.

[0113] A method according to any preceding clause, wherein the second gear pin is deformable and the method further comprises deforming the second gear pin during the reverse torque state so that the second gear pin squeezes the brake fluid reservoir and forces the brake fluid out of the brake fluid reservoir to supply the brake fluid to the one or more braking devices.

[0114] A method as in any preceding clause, the second gear pin comprising a deformable portion, and the brake fluid reservoir being positioned within the second gear pin at the deformable portion.

[0115] A method as in any preceding clause, the second gear pin comprising a rigid portion, and the deformable portion having a stiffness less than that of the rigid portion.

[0116] A method as claimed in any preceding clause, the gearbox assembly comprising a gearbox assembly as claimed in any preceding clause.

[0117] A method according to any preceding clause, further comprising transferring torque from the input shaft to the output shaft through the gear assembly during normal operation of the gearbox assembly such that the input shaft causes the output shaft to rotate.

[0118] A method as defined in any preceding clause, further comprising preventing said one or more braking devices from contacting said gear assembly during said normal operation of said gearbox assembly.

[0119] A method as defined in any preceding clause, further comprising transferring torque from the output shaft to the input shaft via the gearbox assembly during the reverse torque state.

[0120] A method as in any preceding clause, wherein the reverse torque condition occurs when a propeller of the turbine engine is windmilling.

[0121] A method as in any preceding clause, wherein the torque transfer during the reverse torque state is opposite in direction to torque transfer during the normal operation of the gearbox assembly.

[0122] The method of any preceding clause, further comprising applying a gear tooth reverse torque load on the second plurality of gear teeth using the first plurality of gear teeth or the third plurality of gear teeth during the reverse torque state.

[0123] A method as in any preceding clause, further comprising applying a second gear reverse torque load on the second gear pin via the second gear during the reverse torque state.

[0124] A method as in any preceding clause, further comprising deforming the second gear pin via the second gear reverse torque load.

[0125] A method as defined in any preceding clause, further comprising deforming the brake fluid reservoir via the second gear pin during the reverse torque condition.

[0126] A method as in any preceding clause, wherein the one or more braking devices are brake pads.

[0127] A method as defined in any preceding clause, further comprising supplying the brake fluid from the brake fluid reservoir to the one or more braking devices when the second gear pin is deformed during the reverse torque condition.

[0128] A method as in any preceding clause, further comprising generally radially moving the one or more braking devices to contact the second gear during the reverse torque state, thereby braking the gear assembly.

[0129] A method as in any preceding clause, further comprising generally axially moving the one or more braking devices to contact the second gear during the reverse torque state, thereby braking the gear assembly.

[0130] A method as defined in any preceding clause, further comprising moving the first braking device axially forward and the second braking device axially rearward to brake the second gear during the reverse torque state.

[0131] A turbine engine includes a turbocharger having a low-pressure shaft, a propeller having a propeller shaft, and a gearbox assembly. The gearbox assembly includes a gear assembly, the propeller shaft being coupled to the low-pressure shaft via the gear assembly, and a gear braking system, the gear braking system being disposed within the gear assembly and including one or more braking devices, the gear braking system actuating the one or more braking devices to brake the gear assembly during a reverse torque state of the gearbox assembly.

[0132] A turbine engine according to the preceding clause, wherein the gearbox assembly is a gearbox assembly according to any preceding clause.

[0133] A method of operating a turbine engine according to any preceding clause, the method comprising: transferring torque from the propeller shaft to the gear assembly during a reverse torque state; and actuating the one or more braking devices to brake the gear assembly via the torque during the reverse torque state of the gearbox assembly.

[0134] A method as claimed in any preceding clause, comprising braking the gear assembly of a gearbox assembly according to any preceding clause.

[0135] Although the above description is directed to preferred embodiments of the present disclosure, other changes and modifications will be apparent to those skilled in the art and may be made without departing from the present disclosure. In addition, features described in conjunction with one embodiment of the present disclosure may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A gearbox assembly, characterized in that: include: Gear assembly; an input shaft coupled to the gear assembly; an output shaft drivingly coupled to the input shaft through the gear assembly; as well as A gear braking system is disposed within the gear assembly and includes one or more braking devices, the gear braking system actuating the one or more braking devices to brake the gear assembly during a reverse torque condition of the gearbox assembly.

2. The gearbox assembly according to claim 1, characterized in that in, The reverse torque state is when torque is transferred from the output shaft to the input shaft through the gear assembly.

3. The gearbox assembly according to claim 1, wherein: in, The gear braking system includes a brake fluid reservoir storing brake fluid therein, and the gear braking system supplies the brake fluid from the brake fluid reservoir to the one or more braking devices to actuate the one or more braking devices during the reverse torque state.

4. The gearbox assembly according to claim 3, characterized in that: in, The gear brake system includes one or more brake fluid lines in fluid communication with the brake fluid reservoir and the one or more braking devices, and the brake fluid lines direct the brake fluid from the brake fluid reservoir to the one or more braking devices during the reverse torque state.

5. The gearbox assembly according to claim 3, characterized in that in, The gear assembly includes a first gear and a second gear intermeshing with the first gear, and the brake fluid reservoir is disposed within the second gear.

6. The gearbox assembly according to claim 5, characterized in that in, The one or more braking devices are spaced apart from the second gear during normal operation of the gearbox assembly, and the gear braking system actuates the one or more braking devices during the reverse torque state so that the one or more braking devices contact the second gear to brake the gear assembly.

7. The gearbox assembly according to claim 5, characterized in that in, The second gear includes a second gear pin about which the second gear rotates, and the brake fluid reservoir is disposed within the second gear pin.

8. The gearbox assembly according to claim 7, wherein: in, The second gear pin is deformable and deforms during the reverse torque condition such that the second gear pin squeezes the brake fluid reservoir and forces the brake fluid out of the brake fluid reservoir to supply the brake fluid to the one or more braking devices.

9. The gearbox assembly according to claim 8, wherein: in, The second gear pin includes a deformable portion, and the brake fluid reservoir is positioned within the second gear pin at the deformable portion.

10. The gearbox assembly according to claim 9, wherein: in, The second gear pin includes a rigid portion, and the deformable portion has a smaller rigidity than the rigid portion.

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