Lever counterweight feathering system

Abstract

A fan assembly for a gas turbine engine includes a fan disk, a trunnion, an actuation device, fan blades, and a counterweight assembly. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blades are rotatably attached to the fan disk. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, the actuation device, or both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and is disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to gas turbine engines, and more particularly, to gas turbine engines having variable pitch fans. BACKGROUND

[0002] Gas turbine engines generally include a turbine and a rotor assembly. Gas turbine engines, such as turbofan engines, can be used for aircraft propulsion. In the case of turbofan engines, the rotor assembly can be configured as a fan assembly.

[0003] In some gas turbine engines, a variable pitch fan assembly is used to control the pitch of the fan blades. As the pitch of the fan blades is adjusted, the amount of drag of the fan blades is changed. In existing variable pitch fan assemblies, in certain failure modes that lose the ability to control the pitch of the fan blades, the natural centrifugal twist moment of the fan blades will cause the fan blades to rotate to a high drag (e.g., fine) position. In existing engine designs, a feathering system is implemented to address the limited space for addressing the centrifugal twist moment problem that causes undesired blade rotation. SUMMARY

[0004] Aspects and advantages of the disclosure will be set forth in part in the following description, or can be apparent from the description, or can be learned through practice of the

[0005] A fan assembly for a gas turbine engine includes a fan disk, a trunnion, an actuation device, a fan blade, and a counterweight assembly. The fan disk is configured to rotate about an axial centerline of the gas turbine engine. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blade defines a pitch axis and is rotatably attached to the fan disk about its pitch axis by the trunnion. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, the actuation device, or both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and is disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge.

[0006] A counterweight assembly for a gas turbine engine includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is configured to couple with a pitch change mechanism of the gas turbine engine, a trunnion of a fan assembly of the gas turbine engine, or both. The link arm is configured to drive rotation of the trunnion when coupled to the pitch change mechanism, the trunnion, or both. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and is disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge. The counterweight is configured to move in response to a change in centrifugal loading applied to the counterweight during operation of the gas turbine engine.

[0007] A gas turbine engine includes a compressor section, a combustion section, a turbine section, and a fan assembly. The combustion section is connected to and disposed downstream of the compressor section. The turbine section is connected to and disposed downstream of the combustion section. The compressor section, the combustion section, and the turbine section define a core turbine engine. The fan assembly is connected to and disposed upstream of the compressor section. The fan assembly includes a fan disk, a trunnion, an actuation device, fan blades, and a counterweight assembly. The fan disk is configured to rotate about an axial centerline of the gas turbine engine when installed in the gas turbine engine. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blades define a pitch axis and are rotatably attached to the fan disk about their pitch axis by the trunnion. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, the actuation device, or both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and disposed in rotation about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge.

[0008] These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] A complete and enabling description of the present disclosure, directed to those of ordinary skill in the art, follows in the specification along with its best mode, with reference to the accompanying drawings wherein:

[0010] Figure 1 is a schematic cross-sectional view of an exemplary gas turbine engine in accordance with various embodiments of the present subject matter.

[0011] Figure 2 is a perspective exploded view of a fan hub including a plurality of trunnions and counterweight assemblies.

[0012] Figure 3 is a side view of a rotor blade, a trunnion, and a counterweight assembly.

[0013] Figure 4 is a perspective view of a trunnion and a counterweight assembly.

[0014] Figure 5 is a front view of a trunnion and a counterweight assembly.

[0015] Figure 6 is a simplified perspective view of a trunnion and a first counterweight assembly.

[0016] Figure 7 is a simplified perspective view of a trunnion and a second counterweight assembly.

[0017] Figure 8 is a simplified perspective view of a trunnion and third counterweight assembly.

[0018] Figure 9 is a simplified perspective view of a trunnion and fourth counterweight assembly.

[0019] Figure 10 is a simplified side view of a trunnion and counterweight assembly attached to a linear actuator. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to the current embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. The detailed description uses numerical and letter designations

[0021] 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 indicated, the description herein of any implementation is not intended to be exhaustive or to be construed as limiting the scope of the disclosure to the implementation described.

[0022] As used herein, the terms “first,” “second,” and “third” can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle and refer to the normal operational attitude of the gas turbine engine or vehicle. For example, for a gas turbine engine, forward refers to a location closer to the engine inlet and aft refers to a location closer to the engine nozzle or exhaust outlet. The terms “upstream” and “downstream” refer to the relative direction with respect to the fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. Unless otherwise specified herein, the terms “coupled,” “fixed,” “attached to” and the like mean either directly coupled, fixed, or attached as applicable, or indirectly coupled, fixed or attached through one or more intermediate

[0023] As used throughout the specification and claims, approximate language is applied to modify any quantitative representation that can permit variations without changing the basic function to which the representation is directed. Thus, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” is not limited to the precise value specified. In at least some instances, the approximate language can correspond to the precision of an instrument used to measure the value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, the approximate language can refer to within a margin of 1%, 2%, 4%, 10%, 15%, or 20%. These approximate margins can apply to individual values, either end point defining a range of values, and / or a margin of a range between end points.

[0024] Throughout this document and in the 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.

[0025] The present disclosure relates generally to passive pitch systems for fan sections of gas turbine engines. For example, the present disclosure presents various embodiments of lever-weight assemblies attached to a pitch change system for each fan blade of a fan. As the weight actuates in response to centrifugal forces experienced by the weight, the weight assembly imparts torque to a pitch change mechanism, which then rotates the fan blade. The weight is positioned on a lever supported by hinges below the fan rotor hub, without the need for complex gearing. The proposed disclosure allows for a gearless, high mechanical advantage system by positioning the weight and lever components in a plane where there are fewer spatial constraints due to blade-to-blade spacing. Furthermore, the increased lever arm length of the weight helps to minimize the total weight required to achieve the desired pitch capability.

[0026] Reference is now made to the drawings, wherein like numerals refer to like elements throughout, Figure 1 is a schematic cross-sectional view of a gas turbine engine 10 in accordance with various embodiments of the present subject matter. Figure 1 is shown

[0027] More specifically, for embodiments of Figure 1 , the gas turbine engine is a high-bypass turbofan jet engine, referred to herein as “gas turbine engine 10.” As shown Figure 1 , the gas turbine engine 10 defines an axial direction A (extending parallel to an axial centerline 12 provided for reference) and a radial direction R. Generally, the gas turbine engine 10 includes a fan section 14 and a core turbine engine 16 disposed downstream from the fan section 14.

[0028] The core turbine engine 16 depicted herein generally includes a substantially tubular outer casing 18 that defines an annular inlet 20. The outer casing 18 surrounds, in serial flow relationship: a compressor section including a booster or low pressure ("LP") compressor 22 and a high pressure ("HP") compressor 24; a combustion section 26; a turbine section including a high pressure ("HP") turbine 28 and a low pressure ("LP") turbine 30; and an injection exhaust nozzle section 32. In one example, the LP compressor 22 and the HP compressor 24 can be collectively referred to as the compressor section. In another example, the HP turbine 28 and the LP turbine 30 can be collectively referred to as the turbine section. A high pressure ("HP") shaft or spool 34 drivingly connects the HP turbine 28 to the HP compressor 24. A low pressure ("LP") shaft or spool 36 drivingly connects the LP turbine 30 to the LP compressor 22. The compressor section (e.g., the LP compressor 22 and the HP compressor 24), the combustion section 26, the turbine section (e.g., the HP turbine 28 and the LP turbine 30), and the injection exhaust nozzle section 32 together define a core air flowpath 37.

[0029] For the depicted embodiment, the fan section 14 includes a variable pitch fan 38 having a plurality of fan blades 40 coupled to a disk 42 in a spaced apart manner. In one example, the variable pitch fan 38 can be referred to as a fan assembly. In another example, the disk 42 can be referred to as a fan disk. The disk 42 is configured to rotate about the axial centerline 12 of the gas turbine engine 10 when installed therein. As shown, the fan blades 40 extend outwardly from the disk 42 in a generally radial direction R. 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 a suitable trunnion 44 that is configured to collectively and uniformly change the pitch of the fan blades 40. The fan blades 40, the disk 42, and the trunnion 44 are rotatable together about the axial centerline 12 by the LP shaft or spool 36 through a power gear box 46. The power gear box 46 includes a plurality of gears for adjusting the rotational speed of the fan 38 relative to the LP shaft or spool 36 to a more efficient rotational fan speed.

[0030] Still referring to the exemplary embodiment of Figure 1 the disk 42 is covered by a rotatable forward hub 48 that is aerodynamically shaped to facilitate airflow through the plurality of fan blades 40. Additionally, the fan section 14 includes an annular fan casing or outer nacelle 50 that circumferentially surrounds the variable pitch fan 38 and / or at least a portion of the core turbine engine 16. It should be appreciated that the nacelle 50 can be configured to be supported relative to the core turbine engine 16 by a plurality of circumferentially spaced apart outlet guide vanes 52. Moreover, a downstream section 54 of the nacelle 50 can extend over an outer portion of the core turbine engine 16 so as to define a bypass airflow passage 56 therebetween.

[0031] During operation of the gas turbine engine 10, a certain amount of air 58 enters the gas turbine engine 10 through the nacelle 50 and / or the relevant inlet 60 of the fan section 14. As the certain amount of air 58 passes through the fan blades 40, a first portion of the air 58, as indicated by arrow 62, is directed or directed into the bypass airflow passage 56, while a second portion of the air 58, as indicated by arrow 64, is directed or directed into the core airflow path 37, or more specifically, into the LP compressor 22. The ratio of the first portion of air 62 to the second portion of air 64 is commonly referred to as the bypass ratio. Then, as the second portion of air 64 is directed through the high-pressure (HP) compressor 24 and into the combustion section 26, the pressure of the second portion of air 64 increases, where it mixes with fuel and is burned to provide combustion gases 66.

[0032] Combustion gas 66 is directed through HP turbine 28, where a portion of thermal and / or kinetic energy is extracted from the combustion gas 66 via a sequential stage of HP turbine stator blades 68 connected to housing 18 and HP turbine rotor blades 70 connected to HP shaft or spool 34, thereby causing HP shaft or spool 34 to rotate, thus supporting the operation of HP compressor 24. Combustion gas 66 is then directed through LP turbine 30, where a second portion of thermal and kinetic energy is extracted from the combustion gas 66 via a sequential stage of LP turbine stator blades 72 connected to housing 18 and LP turbine rotor blades 74 connected to LP shaft or spool 36, thereby causing LP shaft or spool 36 to rotate, thus supporting the operation of LP compressor 22 and / or the rotation of fan 38.

[0033] Combustion gas 66 is then directed through the injection exhaust nozzle section 32 of the core turbine engine 16 to provide propulsive thrust. Simultaneously, as a first portion of air 62 is directed through the bypass airflow passage 56 before exiting from the fan nozzle exhaust section 76 of the gas turbine engine 10, the pressure of the first portion of air 62 increases significantly, also providing propulsive thrust. The HP turbine 28, LP turbine 30, and injection exhaust nozzle section 32 at least partially define a hot gas path 78 for directing combustion gas 66 through the core turbine engine 16.

[0034] However, it should be understood that Figure 1 The exemplary gas turbine engine 10 depicted herein is merely an example, and in other exemplary embodiments, the gas turbine engine 10 may have any other suitable configuration. It should also be understood that aspects of this disclosure may be incorporated into any other suitable gas turbine engine in other exemplary embodiments. For example, aspects of this disclosure may be incorporated into, for example, a turboprop engine in other exemplary embodiments.

[0035] During operation of the gas turbine engine 10, a failure scenario involving loss of control of the pitch (e.g., degree of rotation) of one or more fan blades 40 can occur. In such a case, the natural centrifugal twist moment of the blade geometry will naturally rotate the fan blades 40 to a high-drag (e.g., fine) position without corrective action. To counteract this natural centrifugal twist moment of the fan blades 40, a feathering device is used to correct the pitch change of the fan blades 40. As discussed herein, “feathering” is a safety feature required to reduce the windmill drag of the variable-pitch fan 38 in the failure scenario of loss of the pitch change capability of one or more fan blades 40.

[0036] Reference is now made to Figure 2 , Figure 2 is a perspective, exploded view of the variable-pitch fan 38 with the trunnions 44 and the counterweight assemblies 80. Figure 2 The axial centerline 12, the variable-pitch fan 38, the pitch axis P, the disk 42, the trunnions 44, and the counterweight assemblies 80 (with each counterweight assembly 80 including a link arm 82, a lever arm 84, a hinge 86, and a counterweight 88) are shown. In this example, the fan blades 40 are omitted for clarity. As shown, Figure 2 In the example shown, the fan blades 40 are omitted for clarity. As shown, Figure 2 The downstream direction is shown as from left to right. In another example, the downstream direction can be from right to left as shown. Figure 2

[0037] As shown, Figure 2 Each trunnion 44 includes a generally tubular shape with a lip or collar on the end of the trunnion 44 closest to the disk 42. In this example, each trunnion 44 is coupled to one of the fan blades 40 (shown in Figure 1 Each trunnion 44 is configured to drive rotation of one of the fan blades 40.

[0038] Each counterweight assembly 80 is operably coupled to one of the trunnions 44. In this example, the counterweight assemblies 80 are evenly distributed along the circumferential direction of the disk 42, with the number of counterweight assemblies 80 matching the number of trunnions 44. The counterweight assemblies 80 are configured to drive rotation of the trunnions 44 in response to centrifugal forces experienced by the counterweights 88.

[0039] ​For the illustrated embodiment, the link arms 82 and lever arms 84 are elongated solid pieces of material. In one example, the link arms 82 and lever arms 84 can comprise rods. The link arms 82 are configured to couple with the trunnions 44. Each link arm 82 connects to and extends between one of the trunnions 44 and one of the lever arms 84. The link arms 82 transfer motion and torque from the lever arms 84 to the trunnions 44. As such, the link arms 82 are configured to drive rotation of the trunnions 44 relative to the disk 42.

[0040] Each lever arm 84 connects to and extends between one of the link arms 82 and one of the weights 88. The connection point of the lever arm 84 to the hinge 86 comprises a pivot (or pivot point). In one example, the lever arm 84 is pivotably or rotatably connected to the link arm 82. In other words, the lever arm 84 and the hinge 86 define a pivot connection point. In another example, the lever arm 84 can be fixedly connected to or engaged with the link arm 82. The lever arm 84 is disposed to transfer movement / motion (e.g., angular motion / rotation) of the weight 88 to the link arm 82.

[0041] In this example, the hinge 86 is a solid piece of material configured to enable another component to rotate about a pivot point of the hinge 86. Each hinge 86 is pivotably connected to one of the lever arms 84. For example, each of the lever arms 84 is disposed to rotate about a connection point of one of the lever arms 84 and one of the hinges 86. The connection point of the lever arm 84 to the hinge 86 comprises a pivot. The hinge 86 provides a pivot about which the lever arm 84 rotates in order to transfer rotation from the lever arm 84 to the link arm 82.

[0042] The weights 88 are heavy objects or solid pieces of material having mass. In this example, the shape of the weights 88 comprises a disk. In other examples, the shape of the weights 88 can comprise a spheroid, an ellipsoid, an angular portion of a flattened ring, a parallelogram, or other geometric shape. Each weight 88 is mounted to an end of one of the lever arms 84 opposite the hinge 86. Each weight 88 is mounted to one of the lever arms 84 at a location spaced apart from one of the hinges 86. Each weight 88 is configured to move in response to changes in centrifugal loading applied to the weight 88 during operation of the variable-pitch fan 38. For example, during certain operational (e.g., fault) modes of the gas turbine engine 10, the fan blades 40 of the variable-pitch fan 38 (as well as the fan blades 40 of the variable-pitch fan 38) can be subjected to changes in centrifugal loading. The changes in centrifugal loading can cause the weights 88 to move, which in turn causes the lever arms 84 to rotate. The rotation of the lever arms 84 is transferred to the link arms 82, which in turn causes the trunnions 44 to rotate relative to the disk 42. As such, the weights 88 are configured to drive rotation of the trunnions 44 relative to the disk 42. Figure 1The rotation will cause the fan blades 40 to rotate to an undesirable high drag (e.g., fine) position in response to the natural centrifugal torsional moment. In response to the centrifugal forces experienced by the counterweights 88, the counterweights 88 impart a torsional moment to the trunnions 44 (via the lever arms 84, hinges 86, and link arms 82) to overcome the centrifugal torsional moment and rotate the fan blades 40 to a low drag or feathered (e.g., coarse) position. The mass, density, and shape of the counterweights 88 can be adjusted and / or customized based on the desired performance characteristics of the counterweight assembly 80. In this example, the single counterweight assembly 80 for each fan blade 40 acts to minimize combined failure modes.

[0043] As presented, the counterweight assembly 80 introduces sufficient torsional moment to each of the blade trunnion axes to overcome the centrifugal torsional moment and rotate each of the fan blades 40 to a low drag or feathered (e.g., coarse) position. Furthermore, as presented, the counterweight assembly 80 is configured such that each of the counterweights 88 is unobstructed by an adjacent counterweight 88. As will be discussed with respect to subsequent figures, Figure 2 As presented, the counterweight assembly 80 is configured such that each of the counterweights 88 is unobstructed by an adjacent counterweight 88. As will be discussed with respect to subsequent figures, Figure 2 The counterweight assemblies are shown positioned in such a way that there are no spacing constraints during operation that inhibit or prevent movement / motion of the counterweights 88 between the fan blades 40 or between adjacent counterweight assemblies 80.

[0044] In certain configurations, the weights can be mounted above the disk, offset from the centerline of the blades. However, in configurations with low radius ratios and higher fan blades, such a configuration cannot be practically packaged and the lack of mechanical advantage can result in the need for heavier weights. As will be discussed with respect to subsequent figures, the mechanical advantage of the counterweight assembly 80 is high due to the pivot point of the hinge 86 being positioned at a lower radial position along the lever arm 84. Due to this high mechanical advantage, the increased length of the lever arm 84 helps to minimize the total weight of the counterweights 88 needed to achieve the desired feathering capability of the counterweight assembly 80.

[0045] Reference is now made to Figure 3 , Figure 3 is a side view of the counterweight assembly 80 attached to the trunnion 44. Figure 3 The pitch axis P, fan blade 40, disk 42, trunnion 44 (with body 90, arm 92, and pin 94), counterweight assembly 80 (with link arm 82, connection point 96, lever arm 84 (including first lever portion 98 and second lever portion 100), hinge 86 (including first hinge portion 102, second hinge portion 104, and pivot 106), counterweight 88), and bearing assembly 108 (with sleeve 110 and ball bearing 112) are shown. In the example shown, Figure 3 The disk 42, sleeve 110, and ball bearing 112 are shown in cross-section in the example shown.

[0046] The body 90 is a solid material tube. The body 90 is mechanically coupled to the fan blade 40 and mounted to the arm 92. The body 90 receives torque from the arm 92 and transmits the torque to the fan blade 40. The arm 92 is an extension of solid material that extends outward in a radial direction from the body 90. The arm 92 is connected to and extends between the body 90 and the pin 94. The arm 92 receives force from the pin 94 and transmits the force to the body 90. The pin 94 is a short rod of solid material that extends in a direction parallel to an axial direction of the body 90 (and parallel to the pitch axis P of the fan blade 40). The pin 94 is rotatably connected to the arm 92 and connects the linkage arm 82 to the arm 92 of the trunnion 44. The pin 94 receives force from the first lever portion 98 and transmits the force to the pin 94.

[0047] The first lever portion 98 and the second lever portion 100 of the lever arm 84 are flat, elongated pieces of solid material. In this example, the first lever portion 98 and the second lever portion 100 are shown misaligned and at an angle Θ LV to each other. In particular, the angle Θ LV between the first lever portion 98 and the second lever portion 100 is shown equal to approximately 90°. In other embodiments, the angle Θ LV may be any angle depending on optimal design considerations. The first lever portion 98 is connected to the second lever portion 100 at the angle Θ LV . The second lever portion 100 is connected to and extends between the first lever portion 98 and the weight 88. The second lever portion 100 transmits torque from the weight 88 to the first lever portion 98. For example, when the weight 88 is subjected to centrifugal force, the second lever portion 100 is pushed along the path 114 and causes the first lever portion 98 to rotate in response to the rotation of the second lever portion 100. The mechanical advantage of the lever arm 84 is produced by the difference in length between the first lever portion 98 and the second lever portion 100.

[0048] For the illustrated embodiment, the first hinge portion 102 and the second hinge portion 104 are elongated pieces of solid material. The first hinge portion 102 is mounted to the disk 42 and extends between the disk 42 and the second hinge portion 104. The first hinge portion 102 secures the hinge 86 to the disk 42. The second hinge portion 104 is pivotably connected to the lever arm 84 and extends between the pivot 106 and the first hinge portion 102. The second hinge portion 104 houses the pivot 106 about which the lever arm 84 rotates.

[0049] Pivot 106 is a fulcrum or point of rotation. In this example, lever arm 84 is arranged to pivot about pivot 106 of hinge 86. Pivot 106 is arranged in second hinge portion 104 of hinge 86. Pivot 106 is connected to hinge 86 and rotatably attaches lever arm 84 to hinge 86. During operation, lever arm 84 rotates about pivot 106 such that weight 88 travels along path 114. In this example, path 114 is shown as an arcuate path that includes a partial circular arc. Similarly, the connection point between link arm 82 and first lever portion 98 of lever arm 84 travels along path 116. In this example, path 116 is shown as also including a partial circular arc. Pivot 106 acts as a fulcrum about which lever arm 84 rotates relative to hinge 86.

[0050] Bearing assembly 108 is a set of components that enables relative rotation between two or more components. Bearing assembly 108 is arranged in and mounted to disc 42. Bearing assembly 108 enables relative rotation between disc 42 and sleeve 110 when weight assembly 80 drives rotation of trunnion 44.

[0051] Sleeve 110 is a generally tubular or frustoconical structure of solid material. Sleeve 110 is mounted in an opening of disc 42. Sleeve 110 provides a structural interface between trunnion 44 and fan blades 40. Ball bearing 112 is a rolling element bearing. Ball bearing 112 is arranged between sleeve 110 and disc 42. Ball bearing 112 rotates or spins relative to sleeve 110 and disc 42 in order to enable rotation of fan blades 40 and trunnion 44 relative to disc 42.

[0052] As described above, weight assembly 80 provides a substantial and effective level of mechanical advantage in driving rotation of trunnion 44 and weight assembly 80 due to the mechanical advantage of lever arm 84 as it rotates about pivot 106 of hinge 86.

[0053] Reference is now made to Figure 4 , Figure 4 is an isometric view of trunnion 44 and weight assembly 80. Figure 4 P, trunnion 44 (having body 90, arm 92, and pin 94), weight assembly 80 (having link arm 82, lever arm 84, hinge 86, and weight 88), path 114, path 116, arm path 118, and direction of rotation 120 are shown.

[0054] Here, Figure 4 Arm path 118 of arm 92 of trunnion 44 and direction of rotation 120 of link arm 82 are included. Arm path 118 of arm 92 shows the rotational movement of arm 92 as weight assembly 80 drives rotation of trunnion 44.

[0055] The rotational direction 120 of the link arm 82 illustrates the path of motion of the link arm 82 as it rotates relative to the connection point between the link arm 82 and the lever arm 84. This rotational direction 120 of the link arm 82 enables the link arm 82 to move with the pin 94 as the arm 93 of the trunnion 44 rotates along the arm path 118. As such, the ability of the link arm 82 to rotate along the rotational direction 120 enables the trunnion 44 to rotate about the pitch axis P while the lever arm 84 of the counterweight assembly 80 rotates along a single plane (see, e.g., Figure 5 ).

[0056] Reference is now made to Figure 5 , Figure 5 is a front view looking back along an axial direction 122 of the trunnion 44 and the counterweight assembly 80. Figure 4 illustrates the pitch axis P, the trunnion 44 (having the body 90, the arm 92, and the pin 94), the counterweight assembly 80 (having the link arm 82, the lever arm 84, the hinge 86, and the counterweight 88), the axial direction 122, and the plane P CW of the counterweight assembly 80.

[0057] The axial direction 122 is a direction oriented in alignment with an axial centerline 12 of the gas turbine engine 10 (see, e.g., Figure 1-2 ). In Figure 5 , the axial direction 122 is oriented into and out of the page. In this example, the axial direction 122 points into and out of the page in a downstream and upstream direction, respectively, relative to the gas turbine engine 10 (as shown in Figure 5 ).

[0058] The plane P CW is an action plane along which the lever arm 84, the hinge 86, and the counterweight 88 are aligned. The plane P CW also represents a translation plane along which the lever arm 84 and the counterweight 88 move or translate during operation of the counterweight assembly 80. For example, with respect to the path 114 of the counterweight 88 shown in Figure 3-4 , the plane P CW is a plane along which the path 114 travels and is aligned. As the plane P CW is shown in Figure 5 as extending into and out of the page, the same alignment of the path 114 into and out of the page is placed.

[0059] In this example, the plane P CW is aligned parallel to the axial direction 122 such that the plane P CW extends into and out of the page. In one example, the plane P CW of the counterweight assembly 80 intersects the axial centerline 12 of the gas turbine engine 10 (see, e.g., the depiction of the axial centerline 12 in Figure 2 ).

[0060] Here in Figure 5 In particular, the plane P CW is shown offset from the pitch axis P to account for the arm path 118 of the arm 92. The plane P CW is also shown misaligned and / or non-parallel with the pitch axis P of the trunnion 44 and extends out of alignment with the fan blade 40 corresponding to the trunnion 44 (shown from Figure 5 for clarity) is omitted). For example, the plane P CW is not aligned with the pitch axis P of the fan blade 40 along the axial direction of the disk 42. In other words, the plane P CW extends at an angle relative to the pitch axis P such that the plane P CW eventually intersects and crosses the pitch axis P. Due to the ability of the link arm 82 to move in and out of the page (as Figure 5 shown) as the lever arm 84 drives the link arm 82 into the page to push the pin 94 and cause the arm 92 to rotate the body 90 about the pitch axis P, the misalignment and offset between the pitch axis P and the plane P CW eliminates the spatial constraints of the counterweight assembly 80 between adjacent fan blades 40. During this operation of the counterweight assembly 80, the components of the counterweight assembly 80 (e.g., the link arm 82, the lever arm 84, the hinge 86, and the counterweight 88) are manipulated without contacting the components of an adjacent counterweight assembly 80 disposed about the disk 42 (see, e.g., Figure 2 ).

[0061] In other words, the misaligned or offset configuration of the counterweight assembly 80 relative to the pitch axis P also allows for a high mechanical advantage system by positioning the components of the counterweight assembly 80 in such a way that the spacing between adjacent fan blades 40 has less spatial constraints.

[0062] Reference is now made to Figure 6 , Figure 6 is a simplified perspective view of the fan blade 40, the trunnion 44, and the counterweight assembly 80 shown in a first configuration. Figure 6 shows the pitch axis P, the fan blade 40, the trunnion 44 (with the body 90, the arm 92, and the pin 94), the counterweight assembly 80 (with the link arm 82, the connection point 96, the lever arm 84 (including the first lever portion 98 and the second lever portion 100), the hinge 86, the counterweight 88, the sleeve 110, the path 114 of the lever arm 84, the arm path 118 of the arm 92, the connection point 124, the connection point 126, and the force F C . In the example shown in Figure 6 , the first lever portion 98 includes a first length LI, and the lever arm 84 includes a second length L2.

[0063] In Figure 6In the simplified view, hinge 86 is shown as a triangle, and in this way, the pivot or fulcrum function of hinge 86 is clearly shown. In this example, hinge 86 is connected to lever arm 84 at one end (e.g., at connection point 126).

[0064] The first length L1 is the length of the first lever portion 98 of the lever arm 84. The second length L2 is the length of the lever arm 84. In this example, the first lever portion 98 and the second lever portion 100 are shown aligned with each other. In such an example, the angle θ LV Equal to 180° (and) Figure 3 Angle θ in LV (Equal to approximately 90°). In other examples, the angle θ LV The range can be from 0° to 90°, from 90° to 180°, or from 180° to 360°.

[0065] In this example, the second length L2 of the lever arm 84 is greater than the first length L1 of the first lever portion 98. This gives the lever arm 84 a mechanical advantage because the counterweight 88 travels a greater distance along path 114 than the connecting point 124 (and the link arm 82) does. As the connecting point 124 travels in response to the rotation of the lever arm 84, the link arm 82 transmits motion from the lever arm 84 to the pin 94, which in turn transmits torque to the trunnion 44.

[0066] Another aspect of this example is that the lever arm 84 is connected to the hinge 86 at connection point 126 located at the distal end of the first lever portion 98. Figure 3-4 compared to, Figure 3-4 The diagram shows hinge 86 connected to a point where the first lever portion 98 connects to the second lever portion 100. Similarly, in... Figure 6 In the example shown, lever arm 84 is connected to link arm 82 at connection point 124, which is located where the first lever portion 98 meets the second lever portion 100 (and...). Figure 3-4 compared to, Figure 3-4 The lever arm 84 is shown connected to the connecting rod arm 82 at the distal end of the first lever portion 98. Since the connection points 124 and 126 include spherical bearing linkages, motion can be transmitted from the counterweight assembly 80 to the trunnion 44 without the use of gears.

[0067] Connection point 124 is the point of connection between link arm 82 and lever arm 84. Connection point 126 is the point of connection between lever arm 84 and hinge 86. In this example, connection points 124 and 126 may include spherical bearings to allow circumferential movement of link arm 82 and lever arm 84.

[0068] Force F CDuring the operation of the gas turbine engine 10, with the disc 42 ( Figure 2 The centrifugal force is applied to the counterweight 88 as it rotates (as shown). For example, the counterweight 88 is configured to respond to the rotation of the variable pitch fan 38 (see example). Figure 1 The force F applied to the counterweight 88 during operation C It moves due to changes in the load (e.g., changes in centrifugal load).

[0069] Figure 6 The embodiment shown provides an example of a first construction of a counterweight assembly 80 having a trunnion 44.

[0070] Now for reference Figure 7 , Figure 7 This is a simplified perspective view of the fan blade 40, trunnion 44, and counterweight assembly 80 shown in the second configuration. Figure 7 The diagram shows the pitch axis P, fan blade 40, trunnion 44 (with body 90, arm 92 and pin 94), counterweight assembly 80 (with linkage arm 82, connection point 96, lever arm 84 (including first lever portion 98 and second lever portion 100), hinge 86, counterweight 88), path 114 of lever arm 84, arm path 118 of arm 92, connection point 124, connection point 126, and force F. C .

[0071] Here Figure 7 In this configuration, hinge 86 connects to lever arm 84 at connection point 124, which is located halfway along the length of lever arm 84. In contrast, in... Figure 6 In this configuration, hinge 86 connects to lever arm 84 at connection point 126, which is located at the distal end of lever arm 84. For example... Figure 7 As shown, hinge 86 is connected to lever arm at a distance from connection point 126, wherein connection point 126 is located at the terminal end or distal end of lever arm 84 (particularly the first lever portion 98).

[0072] Figure 7 The embodiment shown provides a second configuration for the counterweight assembly 80 and the trunnion 44. This alternative configuration allows for flexibility in kinematic design and the ability to change part dimensions to suit any design or operational requirements.

[0073] Now for reference Figure 8 , Figure 8 This is a simplified perspective view of the fan blade 40, trunnion 44, and counterweight assembly 80 shown in the third configuration. Figure 8Pitch axis P, fan blade 40, trunnion 44 (with body 90, arm 92, and pin 94), weight assembly 80 (with link arm 82, connection point 96, lever arm 84 (including first lever portion 98 and second lever portion 100), hinge 86, weight 88, path 114 of lever arm 84, arm path 118 of arm 92, connection point 124, connection point 126, truss arm 128, connection point 130, connection point 132, angular position 134, locking mechanism 136, and force F C .

[0074] Truss arm 128 is a solid material rod. Connection point 130 is the point of connection between second lever portion 100 and truss arm 128. Connection point 132 is the point of connection between first lever portion 98 and truss arm 128. As in the previous embodiment, connection points 130 and 132 can include a spherical ball bearing joint. In this example, truss arm 128 provides additional support to weight assembly 80 by bracing first lever portion 98 to second lever portion 100. Angular position 134 is an imaginary line and represents a predetermined threshold angular position of lever arm 84.

[0075] Locking mechanism 136 is a mechanical fastener. In this example, locking mechanism 136 can include a latching or snap type device, such as a latching bolt or a slam latch. Locking mechanism 136 is disposed along angular position 134. During operation, locking mechanism 136 acts as a lock to prevent any further angular movement of lever arm 84. In one example, locking mechanism 136 can be mounted to disk 42 (as shown in Figure 2 ). In another example, locking mechanism 136 can be mounted to a portion of hinge 86.

[0076] In one example, when weight 88 swings to a fully feathered position during a failure event (of gas turbine engine 10, for example), locking mechanism 136 will engage with lever arm 84 if lever arm 84 reaches angular position 134. Once lever arm 84 reaches angular position 134 and locking mechanism 136 engages with lever arm 84 (or with weight 88), locking mechanism 136 prevents weight assembly 80 from returning to a higher resistance position as the speed of variable pitch fan 38 decreases (as shown in Figure 1-2 ). In one example, the position of angular position 134 and locking mechanism 136 will be beyond the normal operating range of weight assembly 80 and will never be at risk of being triggered during normal, non-failure modes of operation of gas turbine engine 10.

[0077] Here in Figure 8 , hinge 86 is connected to lever arm 84 at connection point 124, which is positioned partially at the point where first lever portion 98 and second lever portion 100 connect to each other. In contrast, in Figure 7 In this embodiment, the hinge 86 is connected to the lever arm 84 at a connection point 124 distal from the distal end of the lever arm 84. As shown, the hinge 86 is connected to the lever arm at a distance from the connection point 126, which is positioned at the terminal endpoint or distal end of the lever arm 84, particularly the first lever portion 98. Figure 8 In this embodiment, the hinge 86 is connected to the lever arm 84 at a connection point 124 distal from the distal end of the lever arm 84. As shown, the hinge 86 is connected to the lever arm at a distance from the connection point 126, which is positioned at the terminal endpoint or distal end of the lever arm 84, particularly the first lever portion 98.

[0078] Figure 8 The embodiment shown provides a third configuration of the counterweight assembly 80 and the trunnion 44. Similar to the embodiment shown in Figure 7 This alternative configuration allows for flexibility in the kinematic design, as well as the ability to change part dimensions to accommodate any design or operational requirements, similar to the embodiment shown in Figure 8 Additional benefits of the configuration shown include additional safety measures (e.g., the locking mechanism 136) during failure modes (e.g., when oil pressure faces a sudden decrease or loss).

[0079] Reference is now made to Figure 9 , Figure 9 is a simplified perspective view of the trunnion 44 and the counterweight assembly 80 shown in a fourth configuration. Figure 9 The lead pitch axis P, the fan blades 40, the trunnion 44 (with the body 90, the arm 92, and the pin 94), the counterweight assembly 80 (with the link arm 82, the connection point 96, the lever arm 84 (including the first lever portion 98 and the second lever portion 100), the hinge 86, the counterweight 88), the sleeve 110, the path 114 of the lever arm 84, the arm path 118 of the arm 92, the connection point 124, the connection point 126, and the force F C .

[0080] Here, Figure 9 the embodiment shown is similar to the embodiment shown in Figure 6 but Figure 9 shows the hinge 86 positioned outwardly in the radial direction from the connection points 124 and 126. Conversely, Figure 6 shows the hinge 86 positioned inwardly in the radial direction from the connection points 124 and 126.

[0081] Figure 9 The embodiment shown in provides a fourth configuration of the counterweight assembly 80 and the trunnion 44. Similar to the embodiments shown in Figure 7 and Figure 8 this alternative configuration allows for flexibility in the kinematic design, as well as the ability to change part dimensions to accommodate any design or operational requirements, as shown in Figure 9

[0082] It will be appreciated that, for clarity, the above description has described embodiments that include certain features only, certain embodiments that exclude other features, and certain embodiments that combine only certain features. It is, of course, possible for certain features to be included in some embodiments, but not in others. Moreover, alternatives can be used in place of or in addition to those described herein. In Figures 2 to 9 ​Certain aspects of the variable pitch fan 38 are omitted in the example embodiment. For example, the example variable pitch fan 38 configurations provided do not include a primary pitch change mechanism, such as a linear or rotary pitch change mechanism. However, it should be appreciated that in each of the above described configurations, a primary pitch change mechanism can be provided that is coupled to the trunnion 44 by an arm separate from the arm 92, such as the body 90 of the trunnion 44. As will be appreciated from the description herein, the counterweight assembly 80 can be used to change the pitch of the variable pitch fan 38 in the event of a failure of the primary pitch change mechanism (not shown).

[0083] Reference is now made to Figure 10 , Figure 10 is a simplified side view of the trunnion 44 and counterweight assembly 80 attached to a primary pitch change mechanism, which for the illustrated embodiment is a linear actuator 138. Figure 10 The pitch axis P, fan blades 40, trunnion 44 (with body 90, arm 92, and pin 94), counterweight assembly 80 (with link arm 82, connection point 96, lever arm 84 (including first lever portion 98 and second lever portion 100), hinge 86, counterweight 88, path 114 of lever arm 84, connection point 124, connection point 126, truss arm 128, connection point 130, connection point 132, linear actuator 138 (with first piece 140, second piece 142, and direction of translation 144), and force F C .

[0084] The linear actuator 138 is an actuation device configured to produce or facilitate linear motion. In some examples, the linear actuator 138 can be referred to as a pitch change mechanism. The first piece 140 is a stationary component of the linear actuator 138. The first piece 140 is disposed to remain stationary relative to the disc 42 (see, e.g., Figure 1-2 ) In one example, the linear actuator 138 can be mounted to the disc 42 (as Figure 2-3The first piece 140 is static relative to the second piece 142, the gimbal 44, and the counterweight assembly 80 during operation of the linear actuator 138. The second piece 142 is the kinematic or movable component of the linear actuator 138. During operation, the second piece 142 moves relative to the first piece 140, the gimbal 44, and the counterweight assembly 80. In this example, the link arm 82 is configured to drive translation of the linear actuator 138. In this example, the link arm 82 is configured to drive linear translation of the linear actuator 138 such that the link arm 82 drives movement or actuation of the second piece 142 in a translation direction 144. The translation direction 144 is the direction of linear movement of the second piece 142 when the second piece is translated relative to the first piece 140. Further, the pin 94 of the gimbal 44 is rotatably connected to the second piece 142 of the linear actuator. For example, the second piece 142 can include a curved path along which the pin 94 travels when the second piece 142 is linearly translated relative to the first piece 140.

[0085] In this example, the linear actuator 138 is incorporated into the configuration of the gimbal 44 and the counterweight assembly 80 (minus the locking mechanism 136) as shown in Figure 8 In other examples, the linear actuator 138 can be combined with any of the configurations shown in Figure 2-9 to connect the counterweight assembly 80 to the gimbal 44. Further, although for the illustrated embodiment the primary pitch change mechanism is a linear actuator 138, other pitch change mechanisms can be provided in other embodiments.

[0086] The incorporation of the linear actuator 138 can provide the benefit of converting forces from the counterweight assembly 80 into more predictable or more efficient linear motion when the force from the link arm 82 is transmitted to the gimbal 44 in the form of a torque. Further, as will be appreciated, coupling the counterweight assembly 80 to the gimbal 44 through a primary pitch change mechanism can open up a variety of additional design options. For example, with such a configuration, the primary pitch change mechanism can effectively act as a coordination ring such that the total number of counterweight assemblies 80 need not match the total number of gimbals 44 and fan blades (as compared to the embodiment of Figure 2 Using such a configuration, the total number of counterweight assemblies 80 can be less than the total number of gimbals 44 and fan blades, potentially resulting in a less complex assembly with heavier counterweights, or alternatively, the total number of counterweight assemblies 80 can be greater than the total number of gimbals 44 and fan blades, potentially resulting in an assembly with smaller counterweights and improved packaging.

[0087] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0088] Further aspects are provided by the subject matter of the following clauses:

[0089] A fan assembly for a gas turbine engine includes a fan disk, a trunnion, an actuation device, fan blades, and a counterweight assembly. The fan disk is configured to rotate about an axial centerline of the gas turbine engine. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blades define a pitch axis and are rotatably attached to the fan disk about their pitch axis by the trunnion. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, the actuation device, or both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge.

[0090] The fan assembly according to one or more of the clauses, wherein the trunnion further includes: a body; an arm connected to the body and extending outwardly from the body in a radial direction; and a pin connected to the arm and extending from the arm, wherein the pin is disposed to rotate relative to the arm.

[0091] The fan assembly according to one or more of the clauses, wherein the link arm is connected to the arm of the trunnion via the pin of the trunnion.

[0092] The fan assembly according to one or more of the clauses, wherein the link arm is pivotably connected to the lever arm.

[0093] The fan assembly according to one or more of the clauses, wherein the hinge is connected to the lever arm at an end of the lever arm.

[0094] The fan assembly according to one or more of the clauses, wherein the hinge is connected to the lever arm at a first length from an end of the lever arm, wherein the first length is greater than zero.

[0095] The fan assembly according to one or more of the clauses, wherein the counterweight is configured to provide an increased force on the trunnion in response to an increased centrifugal load applied to the counterweight during operation of the fan assembly.

[0096] A fan assembly according to one or more of the clauses wherein the counterweight assembly defines a translation plane along which the counterweight translates, wherein the translation plane is not parallel to a pitch axis of the fan blades.

[0097] A fan assembly according to one or more of the clauses wherein the counterweight assembly translates along a translation plane that is misaligned with a pitch axis of the fan blades along an axial direction of the fan disk.

[0098] A fan assembly according to one or more of the clauses wherein the counterweight assembly defines a translation plane along which the counterweight translates, wherein the translation plane is parallel to an axial centerline of the gas turbine engine.

[0099] A fan assembly according to one or more of the clauses wherein the lever arm includes a first portion and a second portion, wherein the first portion of the lever arm extends from a connection point of the lever arm at the hinge to a connection point of the lever arm at the link arm, wherein the first portion of the lever arm defines a first length, wherein the second portion of the lever arm extends from the connection point of the lever arm at the link arm to a distal end of the lever arm, the distal end of the lever arm being at an opposite end of the lever arm from the hinge, wherein the second portion of the lever arm defines a second length, wherein the second length is greater than the first length.

[0100] A fan assembly according to one or more of the clauses wherein the counterweight assembly is configured to swing the counterweight in response to centrifugal forces experienced by the counterweight.

[0101] A fan assembly according to one or more of the clauses wherein the counterweight is configured to swing along an arcuate path.

[0102] A fan assembly according to one or more of the clauses wherein the link arm is connected to an actuation device.

[0103] A fan assembly according to one or more of the clauses wherein the link arm is configured to drive linear translation of the actuation device.

[0104] A fan assembly according to one or more of the clauses wherein the actuation device includes a first piece configured to remain stationary relative to the fan disk and a second piece configured to move relative to the first piece, wherein the link arm is configured to drive linear translation of the second piece in response to translation of the counterweight.

[0105] A counterweight assembly for a gas turbine engine includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is configured to be coupled to a pitch change mechanism of the gas turbine engine, a trunnion of a fan assembly of the gas turbine engine, or both. The link arm is configured to drive rotation of the trunnion when coupled to the pitch change mechanism, the trunnion, or both. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge. The counterweight is configured to move in response to a change in a centrifugal load applied to the counterweight during operation of the gas turbine engine.

[0106] The counterweight according to one or more of the clauses, wherein the counterweight is configured to oscillate about an arcuate path.

[0107] The counterweight according to one or more of the clauses, wherein the counterweight assembly defines a translation plane along which the counterweight translates, wherein the translation plane is parallel to a centerline axis of the gas turbine engine.

[0108] A gas turbine engine includes a compressor section, a combustion section, a turbine section, and a fan assembly. The combustion section is connected to the compressor section and disposed downstream of the compressor section. The turbine section is connected to the combustion section and disposed downstream of the combustion section. The compressor section, the combustion section, and the turbine section define a core turbine engine. The fan assembly is connected to the compressor section and disposed upstream of the compressor section. The fan assembly includes a fan disk, a trunnion, an actuation device, fan blades, and a counterweight assembly. The fan disk is configured to rotate about an axial centerline of the gas turbine engine when installed in the gas turbine engine. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blades define a pitch axis and are rotatably attached to the fan disk about their pitch axis by the trunnion. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, the actuation device, or both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced apart from the hinge.

Claims

1. A fan assembly for a gas turbine engine, characterized by, The gas turbine engine defines an axial direction and an axial centerline, the fan assembly comprising: a fan disk configured to rotate about the axial centerline of the gas turbine engine when installed in the gas turbine engine; a trunnion mounted to the fan disk; an actuation device operably coupled to the trunnion; fan blades defining a pitch axis and rotatably attached to the fan disk about their pitch axis by the trunnion; and a counterweight assembly comprising: a link arm connected to the actuation device; a lever arm connected to the link arm; a hinge pivotably connected to the lever arm, wherein the lever arm is disposed to rotate about a connection point of the lever arm and the hinge; and a counterweight mounted to the lever arm at a location spaced apart from the hinge, wherein the link arm is configured to drive rotation of the trunnion relative to the fan disk by driving linear translation of the actuation device.

2. The fan assembly of claim 1, wherein, wherein, the trunnion further comprises: a body; an arm connected to the body and extending radially outward from the body; and a pin connected to the arm and extending from the arm, wherein the pin is disposed to rotate relative to the arm.

3. The fan assembly of claim 2, wherein, wherein, the actuation device is connected to the arm of the trunnion via the pin of the trunnion.

4. The fan assembly of claim 1, wherein, wherein, the link arm is pivotably connected to the lever arm.

5. The fan assembly of claim 1, wherein, wherein, the hinge is connected to the lever arm at an end of the lever arm.

6. The fan assembly of claim 1, wherein, wherein, the hinge is connected to the lever arm at a first length from an end of the lever arm, wherein the first length is greater than zero.

7. The fan assembly of claim 1, wherein, wherein, the counterweight is configured to provide an increased force on the trunnion in response to an increased centrifugal load applied to the counterweight during operation of the fan assembly.

8. The fan assembly of claim 1, wherein, wherein, the counterweight assembly defines a translation plane along which the counterweight translates, wherein the translation plane is not parallel to the pitch axis of the fan blades.

9. The fan assembly of claim 1, wherein, wherein, the counterweight assembly translates along a translation plane that is not aligned with the pitch axis of the fan blades along an axial direction of the fan disk.

10. The fan assembly of claim 1, wherein, wherein, the counterweight assembly defines a translation plane along which the counterweight translates, wherein the translation plane is parallel to the axial centerline of the gas turbine engine.

11. The fan assembly of claim 1, wherein, wherein, the lever arm comprises a first portion and a second portion, wherein the first portion of the lever arm extends from the connection point of the lever arm at the hinge to a connection point of the link arm at the lever arm, wherein the first portion of the lever arm defines a first length, wherein the second portion of the lever arm extends from the connection point of the link arm at the lever arm to a distal end of the lever arm located at an opposite end of the lever arm from the hinge, wherein the second portion of the lever arm defines a second length, wherein the second length is greater than the first length.

12. The fan assembly of claim 1, wherein, wherein, The weight assembly is configured to oscillate the weight in response to centrifugal forces experienced by the weight.

13. The fan assembly of claim 12, wherein, wherein, The weight is configured to oscillate along an arcuate path.

14. The fan assembly of claim 1, wherein, wherein, The actuation device comprises: a first piece configured to remain stationary relative to the fan disk; and a second piece configured to move relative to the first piece, wherein the link arm is configured to drive linear translation of the second piece in response to translation of the weight.

15. A counterweight assembly for a gas turbine engine, characterized by, The weight assembly comprises: a link arm configured to couple with a pitch change mechanism of the gas turbine engine; a lever arm connected to the link arm; a hinge pivotably connected to the lever arm, wherein the lever arm is configured to rotate about a point of connection of the lever arm and the hinge; and a weight mounted to the lever arm at a location spaced apart from the hinge, wherein the weight is configured to move in response to changes in centrifugal loading applied to the weight during operation of the gas turbine engine, wherein the link arm is configured to drive rotation of the trunnion by driving linear translation of the pitch change mechanism.

16. The counterweight assembly of claim 15, wherein, wherein, The weight is configured to oscillate about an arcuate path.

17. The counterweight assembly of claim 15, wherein, wherein, The weight assembly defines a translation plane along which the weight translates, wherein the translation plane is parallel to a centerline axis of the gas turbine engine.

18. A gas turbine engine defining an axial direction, characterized by, The gas turbine engine comprises: a compressor section; a combustion section connected to and disposed downstream of the compressor section; a turbine section connected to and disposed downstream of the combustion section, wherein the compressor section, the combustion section, and the turbine section define a core turbine engine; and a fan assembly connected to and disposed upstream of the compressor section, wherein the fan assembly comprises: a fan disk configured to rotate about the axial centerline of the gas turbine engine when installed in the gas turbine engine; a trunnion mounted to the fan disk; an actuation device operably coupled to the trunnion; fan blades defining a pitch axis and rotatably attached to the fan disk about their pitch axis by the trunnion; and a weight assembly comprising: a link arm connected to the actuation device; a lever arm connected to the link arm; a hinge pivotably connected to the lever arm, wherein the lever arm is configured to rotate about a point of connection of the lever arm and the hinge; and a weight mounted to the lever arm at a location spaced apart from the hinge, wherein the link arm is configured to drive rotation of the trunnion relative to the fan disk by driving linear translation of the actuation device.

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