WO2021126186A1

WO2021126186A1 - Ultra-high temperature elastomeric alignment & isolation devices

Info

Publication number: WO2021126186A1
Application number: PCT/US2019/067120
Authority: WO
Inventors: Kirk OLSEN; Douglas LEICHT; Allen GEIBEL; Casey HEDLUND; James Halladay
Original assignee: Lord Corporation
Priority date: 2019-12-18
Filing date: 2019-12-18
Publication date: 2021-06-24

Abstract

A system for attaching an aft portion of an aircraft engine to an aircraft structure includes a base mount, a linkage arm that is arranged between opposing inner surfaces of the base mount and moveably attached to the base mount at least at one attachment point, a first alignment ring arranged between a first external surface of the linkage arm and a first inner surface of the opposing inner surfaces of the base mount, and a second alignment ring arranged between a second external surface of the linkage arm and a second inner surface of the opposing inner surfaces of the base mount. Such systems have first and second alignment rings that are made from an ultra-high temperature elastomeric material capable of operating at sustained temperatures of at least 500 °F (260 °C).

Description

ULTRA-HIGH TEMPERATURE ELASTOMERIC ALIGNMENT & ISOLATION

DEVICES

CROSS-REFERENCE TO RELATED APPLICATION

[0001] N/A

FIELD OF INVENTION

[0002] The subject matter disclosed herein generally relates to aircraft engine mounts. More particularly, the subject matter disclosed herein relates to using ultra-high temperature elastomeric devices in aft portions of aircraft engines, in which it has heretofore not been feasible to utilize non-metallic alignment and isolation devices.

BACKGROUND

[0003] Engine mounting systems can connect an engine to a base mount via a linkage. The linkage can be connected to the base mount at one or more connection points. Alignment devices can be implemented at one or more of the connection points. In a “zero” or non- deflected position, the linkage is spaced apart on either side from the base mount. Alignment devices can be provided on each side of the linkage, between the linkage and the base mount, to allow for the linkage to move and/or pivot relative to the base mount in response to dynamic forces transmitted to the linkage during operation. In order to prevent the linkage from excessive deflection the alignment devices apply a centering force that will return the linkage to the “zero” position relative to the base mount. Many areas of an aircraft engine have operating temperatures in excess of temperature limits for use of traditional elastomeric devices, thereby requiring complicated mechanical devices that are almost uniformly made of metallic materials to be able to operate at the high operating temperatures within the engine. The use of such metallic alignment devices has significant disadvantages.

[0004] Example embodiments of known metallic alignment devices, generally designated 400 and 401, are shown in FIGS. 9-12. In these devices, a base plate 410 having receiving portions 412 attached thereon, is provided. A metallic spring 440 is arranged on each side of the base plate 410 and are engaged within the receiving portions 412, so that the springs are engaged against the opposing outer surfaces of the base plate 410. Caps 430 are provided at the distal end of each spring 440 and are positioned against the base mount. The components shown are typically assembled and secured to the base mount by a fastener 450, such as a bolt, that passes through the caps 430, the springs 440, and the base plate 410. As such, when the base plate 410 is displaced along the longitudinal axis of the fastener 450, the spring 440 in the direction in which the base plate 410 is displaced is compressed, while the other spring 440 is correspondingly elongated.

[0005] Among the disadvantages known from the use of metallic alignment devices is the fact that, as the operating temperature of the metal increases, the incidence of plastic, rather than elastic, deformation increases for a given amount of strain. The majority of such metallic alignment devices utilize a resilient metallic structure, such as a helically-wound spring, arranged on opposite sides of the linkage to apply a compressive force from each side of the linkage to return the linkage to the “zero” position. As the springs are compressed due to the dynamic movement of the linkage as the engine moves relative to the aircraft, the spring is repeatedly compressed and extended, depending on whether the movement of the linkage is towards or away from the respective spring. As the operating temperature increases, the amount of permissible deflection of the metallic spring prior to the onset of plastic deformation can decreases, resulting in plastic deformation of the metallic spring rather than elastic deformation and, correspondingly, a resultant reduction in the magnitude of the compressive force, which can lead to increased magnitude deflections of the linkage relative to the base mount, as the corrective compressive force from the plastically deformed metallic spring will be lower than that of the other metallic spring. Additionally, once one or both of the metallic springs has been plastically deformed, the compressive force imparted by each of the metallic springs on the linkage for returning the linkage back to the “zero” position is no longer equal, which can result in the static position of the linkage being shifted away from the “zero” position, such that the linkage is deflected and/or displaced relative to the base mount even when no dynamic forces are being generated that would cause a movement of the linkage relative to the base mount.

[0006] Another disadvantage associated with the use of such metallic alignment devices is due to metal fatigue and damage to other engine components that can occur upon failure of the metallic alignment device. Additionally, the use of metal itself in the alignment features causes metal-to-metal contact between the alignment device and the base mount as well as between the alignment device and the linkage. Upon failure of such metallic devices, whether from repeated thermal cycling, compression cycling, wear due to metal-to-metal contact, and the like, the movement of the linkage relative to the base mount will generally be uncontrolled, allowing unrestrained contact between the linkage and the base mount. Additionally, metallic alignment devices have a potentially catastrophic failure mechanism associated with their use, as fragments of the failed metallic alignment device will form foreign object debris (FOD) that will be distributed throughout the engine downstream of the failed metallic alignment device. These metallic pieces, which could be, for example, part of a spring, a radial shard of a washer, a tabbed portion broken free of a washer, etc., can become lodged in or about other engine components and prevent proper functioning of the engine itself, leading to a potentially catastrophic engine failure scenario. As such, a need presently exists to address the deficiencies associated with the use of metallic alignment devices.

SUMMARY

[0007] This specification discloses systems, devices, and methods for attaching an aft portion of an aircraft engine to an aircraft structure. In one example embodiment, the system comprises a base mount; a linkage arm that is arranged between opposing inner surfaces of the base mount and moveably attached to the base mount at least at one attachment point; a first alignment ring arranged between a first external surface of the linkage arm and a first inner surface of the opposing inner surfaces of the base mount; and a second alignment ring arranged between a second external surface of the linkage arm and a second inner surface of the opposing inner surfaces of the base mount; wherein the first external surface of the linkage arm is on an opposite side of the linkage arm from the second external surface of the linkage arm; and wherein the first and second alignment rings comprise an ultra-high temperature elastomeric material capable of operating at sustained temperatures of at least 500 °F (260 °C).

[0008] In some embodiments of the system, the ultra-high temperature elastomeric material comprises silicone.

[0009] In some embodiments of the system, the first and second alignment rings have a combined thickness that is greater than a combined distance between the first external surface of the linkage arm and the first inner surface of the base mount and between the second external surface of the linkage arm and the second inner surface of the base mount, such that the first and second alignment rings are precompressed between the linkage arm and the base mount. [0010] In some embodiments of the system, the first and second alignment rings are configured to allow a displacement of the linkage arm relative to the base mount about a longitudinal axis of the at least one attachment point.

[0011] In some embodiments of the system, the first and second alignment rings are configured to allow a displacement of the linkage arm relative to the base mount in a plane defined by the longitudinal axis of the at least one attachment point and a longitudinal axis of the linkage arm. [0012] In some embodiments of the system, the first and second alignment rings are configured to substantially inhibit rotation of the linkage arm relative to the base mount about the longitudinal axis of the linkage arm.

[0013] In some embodiments, the system is configured such that at least portions of the first and second alignment rings undergo compression by movement of the linkage arm relative to the base mount, the compression of the first and second alignment rings causing a restorative force in a direction of a “zero”, or non-deflected, position of the linkage arm relative to the base mount.

[0014] In some embodiments of the system, the at least one attachment point comprises a ball joint, about which the linkage arm is pivotable relative to the base mount, or a pin joint, along a length of which the linkage arm is linearly displaceable relative to the base mount. [0015] In some embodiments of the system, the at least one attachment point comprises an inner attachment point and a medial attachment point, the linkage arm being attached to the base mount at each of the inner attachment point and the medial attachment point.

[0016] In some embodiments of the system, the inner attachment point comprises a ball joint, about which the linkage arm is pivotable relative to the base mount, and wherein the medial attachment point comprises a pin joint, along a length of which the linkage arm is linearly displaceable relative to the base mount.

[0017] In some embodiments of the system, the inner attachment point comprises a pin j oint, along a length of which the linkage arm is linearly displaceable relative to the base mount, and wherein the medial attachment point comprises a ball joint, about which the linkage arm is pivotable relative to the base mount.

[0018] In some embodiments of the system, both the inner and medial attachment points comprise a pin mount, along a length of which the linkage arm is linearly displaceable relative to the base mount.

[0019] In some embodiments of the system, alignment rings are arranged on opposite sides of the linkage arm to separate the linkage arm from the base mount at both the inner and medial attachment points.

[0020] In some embodiments of the system, at least one alignment ring has a nonlinear and/or noncontinuous spring force as a function of compression of the at least one alignment ring.

[0021] In some embodiments of the system, the at least one alignment ring has voids, cavities, and/or notches formed in portion thereof to make the portion more susceptible to compression than other portions of the at least one alignment ring. [0022] In some embodiments of the system, one or more further alignment rings are arranged, along with the first and/or second alignment rings, between the linkage arm and the base mount.

[0023] In some embodiments of the system, the first and/or second alignment rings and the one or more further alignment rings have different stiffness values.

[0024] In some embodiments of the system, each of the first alignment ring and/or the second alignment ring and the one or more further alignment rings have different stiffness values.

[0025] In some embodiments of the system, the first alignment ring has a different stiffness from a stiffness of the second alignment ring, such that a force and/or torque necessary to cause a movement of the linkage arm towards the base mount in a direction of the first alignment ring is not the same as a force and/or torque necessary to cause the movement of the linkage arm towards the base mount in a direction of the second alignment ring, wherein the movement of the linkage arm towards the base mount in the direction of the first alignment ring is a same magnitude as the movement of the linkage arm towards the base mount in the direction of the second alignment ring.

[0026] In some embodiments of the system, the first and second alignment rings are non- metallic, such that, upon failure, the first and/or second alignment rings are configured to disintegrate and be burned by exhaust from the aircraft engine so as to not impair operation of any other components of the aircraft engine upon such failure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 A is an isometric view of an isolator ring for use in aligning a linkage with a base mount in an aircraft engine.

[0028] FIG. IB is a front view of the isolator ring shown in FIG. 1 A.

[0029] FIG. 2 is an isometric view of an engine mount system in which a linkage is spaced apart from the base mount by the isolator rings, which are shown in FIGS. 1 A and IB, installed on either side of the linkage.

[0030] FIG. 3 is a partial sectional isometric view of the engine mount system of FIG. 2.

[0031] FIG. 4 is a partial sectional front view of the engine mount system of FIG. 2.

[0032] FIG. 5 A is a side view of the engine mount system of FIG. 2. [0033] FIG. 5B is a side view of the engine mount system of FIG. 2, in which the linkage is in a deflected position relative to the base mount.

[0034] FIG. 6A is a detailed side view of the engine mount system of FIG. 2, showing the isolator rings spacing the linkage apart from the base mount.

[0035] FIG. 6B is an internal view of the engine mount system shown in FIG. 6A.

[0036] FIG. 7 is a view of the engine mount system of FIG. 2, taken along the longitudinal axis of the linkage.

[0037] FIG. 8 is a side view of a second embodiment of an engine mount system.

[0038] FIG. 9 is a side view of a metallic alignment device from the prior art.

[0039] FIG. 10 is a front view of the metallic alignment device of FIG. 9.

[0040] FIG. 11 is a front view of a metallic alignment device from the prior art.

[0041] FIG. 12 is a partial sectional view of the metallic alignment device of FIG. 11, taken along the line 12-12 in FIG. 11.

DETAILED DESCRIPTION

[0042] This specification discloses systems, devices, and methods for providing compliant alignment between a linkage arm to a base mount, allowing the linkage arm to pivot in at least two planes about the point at which the linkage arm is attached to the base mount, but substantially preventing any twisting of the linkage arm relative to the base mount along the longitudinal axis of the linkage arm. The linkage arm may be connected to the base mount at any suitable number of attachment points, including, but not limited to, via a ball joint, a pin joint, or combinations of ball and pin joints at various positions along the length of the linkage arm where it is advantageous to attach the linkage arm to the base mount. In a pin joint, the linkage arm is slidable towards the base mount in either direction along the longitudinal axis of the pin securing the linkage arm to the base mount. This direction will be defined and used herein as being along the X-axis. In a ball joint, the linkage arm is held substantially stationary in the X-direction. In both ball and pin joints, the linkage arm is able to rotate about the X-axis. In a ball joint, the linkage arm is able to pivot about the ball as it rotates about the X-axis, such that the linkage arm can be either perpendicular or non-perpendicular to the X-axis.

[0043] In some embodiments, at least two attachment points are provided between the linkage arm and the base mount, an inner attachment point and an medial attachment point. In some such embodiments, both the inner and medial attachment points are pin joints. In some other such embodiments, the inner attachment point is a ball joint and the medial attachment point is a pin joint. In still some other such embodiments, the inner attachment point is a pin joint and the medial attachment point is a ball joint. In order to ensure that the linkage arm is capable of moving as described herein under dynamic loads transmitted to the linkage arm, it is necessary for the linkage to be returned to a “zero,” or reference, position when not being acted on by a load that positionally shifts the linkage arm relative to the base mount. FIG. 1 shows an example embodiment of a an alignment ring, generally designated 100, that allows relative linear and/or angular movements between a linkage arm and a base mount under dynamic or static loading of the linkage arm, but applies a centering force to restore the linkage arm to the “zero” position relative to the base mount, in which position the linkage arm is not positionally and/or angularly deflected relative to the base mount.

[0044] The alignment ring 100 has a generally annular shape, but other shapes are contemplated without deviating from the scope of the disclosed subject matter. The alignment ring 100 has a body 110 with a hole 130 formed through a thickness of the body 110, the hole 130 being defined by the inner surface 120 of the body 110. The body 110 extends radially between the inner surface 120 and the outer surface 140. A circumferential slot 150 is formed between the inner surface 120 and the outer surface 140 to aid in assembly of the linkage arm to the base mount at the attachment point. The distance between the inner surface 120 and the outer surface 140 can be non-uniform and holes, voids, and other features may be formed in and/or through the body 110 of the alignment ring 100 to cause the ring to have a variable stiffness based on the radial position of the linkage arm relative to the alignment ring 100. In some embodiments, the slot 150 can be omitted entirely.

[0045] FIGS. 2 through 7 show an example embodiment of an engine mount system, generally designated 200, in which a linkage arm 230 is displaceably connected to a base mount 210 fur use in attaching an aft portion of an aircraft engine to an aircraft structure, e.g., an aircraft engine support pylon. In the example embodiment shown, the base mount 210 is formed of first and second portions 212, 214 that are joined together by fasteners 218 at an interface 216 between the first and second portions 212, 214. This construction allows for easier assembly of the linkage arm 230 to the base mount 210. In the embodiment shown, there are two linkage arms 230, 230A that are attached to the base mount 210, the linkage arms 230, 230A extending away from the base mount 210 in any desired directions, but in the embodiment shown, extending away from the base mount 210 in a substantially coplanar manner, but inclined relative to each other such that linkage arms 230, 230A are not parallel with each other. The base mount 210 can be attached to either the aircraft engine, in which case the linkage arms 230, 230A are attached to the aircraft support structure, or to an aircraft support structure, in which case the linkage arms 230, 230A are attached to the aircraft engine.

[0046] The linkage arms 230, 230A are able to move independently of, or in unison with, each other under dynamic loads, e.g., forces, that are transmitted between the aircraft engine and the aircraft structure to which the aircraft engine is attached. In the embodiment shown, the linkage arms 230, 230A are substantially geometrically identical. The attachments of the linkage arms 230, 230A can be substantially similar or different from each other at each attachment point between the linkage arm 230, 230A and the base mount, however the attachment of the linkage arms 230, 230A to the base mount 210 will be discussed herein relative to linkage arm 230. Linkage arm 230 is connected to the base mount 210 at an inner attachment point, generally designated 250, and at a medial attachment point, generally designated 270, which is located along the length of the linkage arm 230 between the inner attachment point and the outer attachment point, generally designated 290, which is the location where the linkage arm 230 is attached to either the aircraft engine or the aircraft structure, whichever of which the base mount 210 is not attached. In the embodiment shown, the inner attachment point 250 is a ball joint and the medial attachment point 270 is a pin joint, such that the linkage arm 230 pivots about the inner attachment point 250 and slides along the length of the pin securing the linkage arm 230 to the base mount 210 at the medial attachment point 270. The outer attachment point 290 can be any suitable type of attachment, including a rigid attachment, ball joint, pin joint, and the like, to secure the linkage arm 230 to either the aircraft engine or the aircraft structure.

[0047] FIG. 3 is a partial sectional view of the engine mount system 200, in which a portion of the base mount 210 is sectioned out so that the internal details of the attachment of the linkage arm 230 to the base mount 210 at the inner attachment point 250 and the medial attachment point 270 can be shown. At the inner attachment point 250, the linkage arm 230 is pivotably connected to the base mount 210 by a ball joint 252, which is secured to the base mount 210 by a fastener 254, which can be a pin, bolt, or any suitable type of fastener. The linkage arm has a hole (232, FIG. 5A) formed through a thickness thereof to allow for the pivoting attachment of the linkage arm 230 to the ball joint at the inner attachment point. The linkage arm 230 is spaced apart from the base mount 210 on each side of the linkage arm 230 by an alignment ring 100. As such, an alignment ring 100 is shown being arranged on both sides of the linkage arm 230. In the embodiment shown, the alignment rings 100 have a thickness that is substantially the same as the distance between the adjacent planar surfaces of the linkage arm 230 and the base mount 210. In some embodiments, the alignment rings 100 are installed between the linkage arm 230 and the base mount 210 in a precompressed manner, such that a restorative force is applied by the alignment rings 100 to the linkage arm 230 on both sides of the linkage arm 230. In an example embodiment allowing for such precompression of the alignment rings 100, the alignment rings 100 are dimensioned to have an uncompressed thickness that is greater than the distance, as measured from the “zero” or non-deflected position, between the exterior surface of the linkage arm 230 and the adjacent inner surface of the base mount 210 facing the exterior surface of the linkage arm 230 against which the alignment ring 100 will be pressed against, for example, directly against, during operation to apply the restorative force to the linkage arm 230. Thus, in embodiments where each of the alignment rings 100 are each precompressed between the linkage arm 230 and one of the inner surfaces of the base mount 210, a restorative force is generated by each of the alignment rings 100 even when the linkage arm 230 is at the “zero” position. In embodiments of the system 200 in which the alignment rings 100 are precompressed, the combined thicknesses of the alignment rings 100 are greater than the combined distances between the external surfaces of the linkage arm 230 and the corresponding adjacent inner surface of the base mount 210.

[0048] At the medial attachment point 270, the linkage arm 230 has a sleeve 276 arranged concentrically within a hole, generally designated 234, formed through the linkage arm 230. The sleeve 276 is configured to engage with a pin 272 to allow for the linkage arm 230 to slide along the length of the pin 272. The pin 272 is secured to the base mount 210 by a fastener 274, which can be a pin, bolt, or any suitable type of fastener. The sleeve 276 and the pin 272 have compatible keyed features 278 that prevent relative twisting or pivoting movements of the sleeve 276 relative to the pin 272, which thereby prevents any rotation of the linkage arm 230 relative to the pin 272 and, consequently, base mount 210. At the outer attachment point 290, an attachment pin 300 is shown, which can be part of, or otherwise associated with, the aircraft engine and/or the aircraft structure. The linkage arm 230 has a hole, generally designated 236, in which a sleeve 294 is arranged to allow for the linkage arm to move along the longitudinal axis of the attachment pin 300. In some embodiments, the linkage arm 230 may be rigidly connected to the aircraft engine or the aircraft structure at the outer attachment point 290, whether via hole 236 or any other suitable type of attachment. [0049] FIG. 4 shows that the alignment rings 100 allow for, or at least do not prevent, relative movement between the linkage arm 230 and the base mount 210 in the direction Rl. In embodiments where medial attachment point 270 is omitted or, otherwise, where the linkage arm 230 is connected to the base mount 210 at only the inner attachment point 250, the alignment rings 100 do not inhibit rotation of the linkage arm 230 relative to the base mount 210 about the inner attachment point 250. However, in the embodiment shown, the rotary movement of the linkage arm 230 relative to the base mount 210 about the inner attachment point is inhibited by the attachment of the linkage arm 230 to the base mount 210 at the medial attachment point 270.

[0050] FIGS. 5 A and 5B show that the alignment rings 100 allow for relative pivoting movements between the linkage arm 230 and the base mount 210 in the direction R2. Since, in the embodiment shown, the linkage arm 230 is attached to the base mount 210 at the inner attachment point by a ball joint passing through the hole 232 formed through the linkage arm, the linkage arm 230 is positionally fixed relative to the base mount 210 at the inner attachment point 250, the ball joint allowing only pivoting movements of the linkage arm 230 relative to the base mount 210. The pin joint at the medial attachment point 270 allows for the linkage arm to slide in both directions along the longitudinal axis of the fastener 274, such that the linkage arm 230 can be inclined relative to the “zero,” or non-deflected, position shown in FIG. 5A. An example of such an inclined position of the linkage arm 230 in shown in FIG. 5B. The alignment rings 100 are omitted from FIG. 5B, however, when the linkage arm 230 is displaced as shown in FIG. 5B, the upper portion of the left alignment ring 100 and the lower portion of the right alignment ring 100 shown in FIG. 5A are each compressed. It is this compression of the alignment rings 100 due to movement of the linkage arm 230 relative to the base mount 210 that generates a restorative force that, in the absence of the forces that cause the initial deflection of the linkage arm 230 relative to the base mount 210, will return the linkage arm 230 back to the “zero” position shown in FIG. 5A. As such, when the alignment rings 100 are compressed, a restorative force is applied by the compressed portions of the alignment rings 100 to the linkage arm 230 at the inner attachment point 250 in a direction that would cause the linkage arm 230 to pivot about the inner attachment point 250 to return to the “zero” position shown in FIG. 5A. The inner surfaces of the base mount 210 act as snubbing points where direct contact between the linkage arm 230 and these surfaces of the base mount 210 limit the amount of deflection, whether linear and/or rotary in nature, of the linkage arm 230 relative to the base mount 210. [0051] In the embodiment shown in FIG. 5B, the second linkage arm 230A is also deflected relative to the base mount 210 in a direction opposite the direction in which the first linkage arm 230 is deflected. As such, the restorative force imparted to the second linkage arm 230 is independent of the movement of the first linkage arm 230 and, consequently, is also independent of the orientation of the restorative force applied to the first linkage arm 230. The permitted movement of the linkage arms 230, 230A relative to the base mount 210 is defined in the embodiment shown by the effective length of the fastener 274 between the inner faces of the base mount 210 at the medial attachment point. Decreasing the distance between the inner faces of the base mount 210 at the medial attachment point will decrease the amount of angular rotation of the linkage arm 230 permitted relative to the base mount 210, as the amount of angular rotation of the linkage arm 230 about the inner attachment point 250 before the linkage arm 230 before the linkage arm 230 contacts one of the inner surfaces of the base mount 210 at or adjacent to the medial attachment point will decrease, thereby reducing the range of angular movements of the linkage arm 230 about the inner attachment point 250. Correspondingly, increasing the distance between the inner faces of the base mount 210 at the medial attachment point will increase the amount of angular rotation of the linkage arm 230 permitted relative to the base mount 210, as the amount of angular rotation of the linkage arm 230 about the inner attachment point 250 before the linkage arm 230 before the linkage arm 230 contacts one of the inner surfaces of the base mount 210 at or adjacent to the medial attachment point will increase, thereby increasing the range of angular movements of the linkage arm 230 about the inner attachment point 250.

[0052] The linkage arm 230 has a hole 234 formed through a thickness of the linkage arm 230, through which the pin 272 passes to maintain sufficiently precise alignment of the linkage arm 230 and the base mount 210. The hole 234 has dimensions sufficiently large to allow for the linkage arm 230 to move along the pin 272 without binding over the total range of motion of the linkage arm 230 relative to the base mount 210. In some embodiments, alignment rings 100 may be provided at the medial attachment point 270 to apply a restorative force to the linkage arm 230 to cause the linkage arm 230 to move away from the alignment ring 100 being compressed and back towards the “zero” position. In some such embodiments, one alignment ring 100 can be provided on each side of the linkage arm 230 between an external surface of the linkage arm 230 and the corresponding inner surface of the base mount 210 at the medial attachment point. This alignment ring 100 can have an uncompressed thickness dimension that is substantially the same as the distance between external surface of the linkage arm 230 and the corresponding inner surface of the base mount 210 at the medial attachment point 270, where the alignment ring 100 is to be installed. In such embodiments, substantially the entire distance between the opposing inner surfaces of the base mount 210 can be occupied by alignment rings 100 and the linkage arm 230 itself. In some embodiments, the alignment rings 100 at the medial attachment point 270 can be installed so as to be precompressed between the linkage arm 230 and the base mount 210, as is described elsewhere herein regarding the precompression of the alignment rings 100 at the inner attachment point 250.

[0053] In some embodiments, it can be advantageous to have alignment rings 100 having variable stiffness, such that the restorative force applied by the compressed alignment ring 100 to the linkage arm 230 increases non-linearly, e.g., having a discontinuous spring force curve as a function of deflection and/or compression of the alignment ring 100. In some such embodiments, the alignment rings 100 can have cavities, voids, notches, or the like formed in a portion thereof that allow for initial compression of the alignment ring 100 to be achieved with comparatively smaller compressive forces, while another portion of the alignment rings 100 can have, for example, a solid construction that will be more resistant to compression. In some other embodiments, a plurality of alignment rings 100 may be stacked between the linkage arm 230 and the base mount 210, on each side of the linkage arm 230. In such embodiments, at least one of the alignment rings 100 may have a lower spring coefficient than at least another of the alignment rings 100, thereby increasing the restorative force applied to the linkage arm 230 in a non-linear and/or step-wise manner based on the amount of compression of each of the alignment rings 100. In any such embodiments, the thickness of the alignment ring(s) 100 on a first side of the linkage arm 230 may be different from the thickness of the alignment ring(s) 100 on a second side of the linkage arm 230, thereby causing the “zero” position of the linkage arm to be inclined relative to the base mount 210, such that a distance between the linkage arm 230 and a first inner surface of the base mount 210 on a first side of the linkage arm 230 is different between a distance between the linkage arm 230 and a second inner surface of the base mount 210 on a second side of the linkage arm 230.

[0054] In some other embodiments, an alignment ring 100 may be arranged on each side of the linkage arm 230, between the linkage arm 230 and the inner surface of the base mount 210 at the medial attachment point 270. In such embodiments, it can be advantageous for the thickness of one or both of the alignment rings 100 to have a thickness that is less than a distance between the external surface of the linkage arm 230 and the corresponding adjacent inner surface of the base mount 210. In such embodiments, the linkage arm 230 may be freely displaceable at the medial attachment point 270 over a prescribed distance, which can be non- uniform in the direction along the longitudinal axis of the pin 272, relative to the “zero” position of the linkage arm 230. Thus, the restorative force is only imparted to the linkage arm 230 at the medial attachment point 270 after the linkage arm 230 is sufficiently deflected to contact one of the alignment rings 100.

[0055] The arrangement of the alignments rings 100 at the medial attachment point 270 described herein can be applied at the medial attachment points 270 of both of the linkage arms 230, 230A of the engine support system 200 in any combination. By way of example, it is noted that the linkage arm 230 may be surrounded by alignment rings 100 of variable stiffness, while the linkage arm 230A may have gaps between alignment rings 100 of asymmetric thickness arranged on either side thereof. In some embodiments, alignment rings 100 may be installed at the medial attachment point 270 and/or at the inner attachment point of the linkage arm 230 and alignment rings 100 may be omitted either partially and/or entirely at the medial attachment point 270 and/or at the inner attachment point of the linkage arm 230A.

[0056] FIGS. 6 A and 6B are detailed views of the engine support system 200, showing the linkage arm 230 spaced apart from the respective inner surfaces of the base mount 210 on opposite sides of the linkage arm 230 at the inner attachment point. In the embodiment shown, the alignment rings 100 are arranged on opposite sides of the linkage arm 230 to occupy substantially all of the distance between the opposing inner surfaces of the base mount 210.

[0057] FIG. 7 is a view of the engine mount system 200 taken along the longitudinal axis of the linkage arm 230. Unlike in the direction R2 shown in FIG. 5A, in which the length of the linkage arm 230 acts as a lever arm to apply a torque against the alignment rings 100 to allow the compression of the alignment rings 100 by the linkage arm 230 acting thereon, any force transmitted to the linkage arm 230 in the direction R3 shown in FIG. 7 would be applied to the linkage arm 230 at or adjacent the longitudinal axis of the linkage arm 230. This means that, in relation to the ability of the force transmitted to the linkage arm 230 to impart a torque that would cause a twisting motion of the linkage arm 230 at the inner attachment point 250 in the direction R3, the effective length of the linkage arm 230 is negligible and the torque that could be transmitted to the linkage arm 230 would require forces on the order of about ten times that of the forces in the R1 or R2 direction and would not be able to cause a significant rotation of the linkage arm 230 in the direction R3 that would compress beyond a negligible amount (e.g., 10% or less, 5% or less, 2% or less, 1% or less, etc.) any portion of the alignment rings 100. As such, the alignment rings 100 of the engine mount system 200 are configured to allow no, or only negligible, rotation of the linkage arm 100 relative to the base mount 100 about the longitudinal axis of the linkage arm 230 in the direction R3, while allowing movement, whether linear or rotational, of the linkage arm 230 relative to the base mount 210 in the directions R1 and R2, which are transversely oriented to the longitudinal axis of the linkage arm 230.

[0058] The alignment rings 100 disclosed in each of the embodiments disclosed herein are made from an ultra-high temperature elastomeric material, which can withstand ambient temperatures that are typical in aft portions of an aircraft engines that have traditionally required metallic alignment devices due to the elevated temperatures at these installation locations. Using elastomeric materials in such locations would cause the elastomeric material to degrade rapidly and fail, leaving the movements of the linkage arm (230, FIGS. 2-8) relative to the base mount (210, FIGS. 2 through 8) uncontrolled and undamped. For example, the alignment rings 100 disclosed herein can withstand prolonged exposure (e.g., substantially continuously) at up to 500 °F (260 °C), withstanding time-limited temperature surges (e.g., having a duration of less than 15 minutes) of up to 600 °F (315 °C). In some embodiments, the ultra-high temperature elastomeric material is a silicone-based material. In some embodiments, the ultra-high temperature elastomeric material is able to withstand temperatures as high as 575 °F (302 °C) for at least 1% of the operating time of the engine mount system 200, temperatures as high as 525 °F (274 °C) for at least 9% of the operating time of the engine mount system 200, and temperatures as high as 500 °F (260 °C) for at least 90% of the operating time of the engine mount system 200. The percentages of operating time listed above are based on a 24- hour calendar time.

[0059] FIG. 8 is another example embodiment of the engine support system 200, in which, instead of the ball joint used at the inner attachment point 250 in the embodiment of FIGS. 2- 7, a pin joint is used to allow the linkage arm 230 to move laterally along the length of the pin (e.g., 272, FIG. 3) at the inner attachment point 250A. While some pivoting of the linkage arm 230, resulting in the linkage arm 230 being inclined relative to the base mount 230 from the parallel orientation shown in FIG. 8 will inevitably result due to the fact that the holes 232, 234 formed through the linkage arm 230 are at least somewhat larger than the pins at the inner and medial attachment points 250A, 270 passing through the holes 232, 234, the primary movement of the linkage arm 230 relative to the base mount 210 will be linear and/or translator in nature, not pivoting and/or rotational. The embodiment of the system 200 shown in FIG. 8 has alignment rings 100 arranged between the linkage arm 230 and the base mount 210 on both sides of the linkage arm 230 at the inner attachment point 250A.

[0060] The linkage arm 230 is spaced apart from the base mount 210 on each side of the linkage arm 230 by an alignment ring 100. As such, an alignment ring 100 is shown being arranged on both sides of the linkage arm 230. In the embodiment shown, the alignment rings 100 have a thickness that is substantially the same as the distance between the adjacent planar surfaces of the linkage arm 230 and the base mount 210. In some embodiments, the alignment rings 100 are installed between the linkage arm 230 and the base mount 210 in a precompressed manner, such that a restorative force is applied by the alignment rings 100 to the linkage arm 230 on both sides of the linkage arm 230. In an example embodiment allowing for such precompression of the alignment rings 100, the alignment rings 100 are dimensioned to have an uncompressed thickness that is greater than the distance, as measured from the “zero” or non-deflected position, between the exterior surface of the linkage arm 230 and the adjacent inner surface of the base mount 210 facing the exterior surface of the linkage arm 230 against which the alignment ring 100 will be pressed against, for example, directly against, during operation to apply the restorative force to the linkage arm 230. Thus, in embodiments where each of the alignment rings 100 are each precompressed between the linkage arm 230 and one of the inner surfaces of the base mount 210, a restorative force is generated by each of the alignment rings 100 even when the linkage arm 230 is at the “zero” position.

[0061] As was described regarding the engine mount system 200 shown in FIGS. 2 through 7, the alignment rings 100 in the embodiment of FIG. 8 allow for, or at least do not prevent, relative movement between the linkage arm 230 and the base mount 210 in the direction R1 (see, e.g., 4). In embodiments where medial attachment point 270 is omitted or, otherwise, where the linkage arm 230 is connected to the base mount 210 at only the inner attachment point 250A, the alignment rings 100 do not inhibit rotation of the linkage arm 230 relative to the base mount 210 about the inner attachment point 250A. However, in the embodiment shown, the rotary movement of the linkage arm 230 relative to the base mount 210 about the inner attachment point is inhibited by the attachment of the linkage arm 230 to the base mount 210 at the medial attachment point 270.

[0062] When the linkage arm 230 is displaced in the direction L2, the upper portion of the left alignment ring 100 and the lower portion of the right alignment ring 100 are each compressed. It is this compression of the alignment rings 100 due to movement of the linkage arm 230 relative to the base mount 210 that generates a restorative force that, in the absence of the forces that cause the initial deflection of the linkage arm 230 relative to the base mount 210, will return the linkage arm 230 back to the “zero” position shown in FIG. 8. As such, when the alignment rings 100 are compressed, a restorative force is applied by the compressed portions of the alignment rings 100 to the linkage arm 230 at the inner attachment point 250A in a direction that would cause the linkage arm 230 to move along the length of the pin by which the linkage arm 230 is secured to the base mount 210 at the inner attachment point 250A, thereby pressing against the linkage arm 230 so as to return the linkage arm 230 to the “zero” position shown in FIG. 8. The inner surfaces of the base mount 210 act as snubbing points where direct contact between the linkage arm 230 and these surfaces of the base mount 210 limit the amount of deflection, whether linear and/or rotary in nature, of the linkage arm 230 relative to the base mount 210.

[0063] In some embodiments, alignment rings 100 may be provided at the medial attachment point 270 to apply a restorative force to the linkage arm 230 to cause the linkage arm 230 to move away from the alignment ring 100 being compressed and back towards the “zero” position. In some such embodiments, one alignment ring 100 can be provided on each side of the linkage arm 230 between an external surface of the linkage arm 230 and the corresponding inner surface of the base mount 210 at the medial attachment point. This alignment ring 100 can have an uncompressed thickness dimension that is substantially the same as the distance between external surface of the linkage arm 230 and the corresponding inner surface of the base mount 210 at the medial attachment point 270, where the alignment ring 100 is to be installed. In such embodiments, substantially the entire distance between the opposing inner surfaces of the base mount 210 can be occupied by alignment rings 100 and the linkage arm 230 itself. In some embodiments, the alignment rings 100 at the medial attachment point 270 can be installed so as to be precompressed between the linkage arm 230 and the base mount 210, as is described elsewhere herein regarding the precompression of the alignment rings 100 at the inner attachment point 250A.

[0064] In some embodiments, it can be advantageous to have alignment rings 100 having variable stiffness, such that the restorative force applied by the compressed alignment ring 100 to the linkage arm 230 increases non-linearly, e.g., having a discontinuous spring force curve as a function of deflection and/or compression of the alignment ring 100. In some such embodiments, the alignment rings 100 can have cavities, voids, notches, or the like formed in a portion thereof that allow for initial compression of the alignment ring 100 to be achieved with comparatively smaller compressive forces, while another portion of the alignment rings 100 can have, for example, a solid construction that will be more resistant to compression. In some other embodiments, a plurality of alignment rings 100 may be stacked between the linkage arm 230 and the base mount 210, on each side of the linkage arm 230. In such embodiments, at least one of the alignment rings 100 may have a lower spring coefficient than at least another of the alignment rings 100, thereby increasing the restorative force applied to the linkage arm 230 in a non-linear and/or step-wise manner based on the amount of compression of each of the alignment rings 100. In any such embodiments, the thickness of the alignment ring(s) 100 on a first side of the linkage arm 230 may be different from the thickness of the alignment ring(s) 100 on a second side of the linkage arm 230, thereby causing the “zero” position of the linkage arm to be inclined relative to the base mount 210, such that a distance between the linkage arm 230 and a first inner surface of the base mount 210 on a first side of the linkage arm 230 is different between a distance between the linkage arm 230 and a second inner surface of the base mount 210 on a second side of the linkage arm 230.

[0065] In some other embodiments, an alignment ring 100 may be arranged on each side of the linkage arm 230, between the linkage arm 230 and the inner surface of the base mount 210 at the medial attachment point 270. In such embodiments, it can be advantageous for the thickness of one or both of the alignment rings 100 to have a thickness that is less than a distance between the external surface of the linkage arm 230 and the corresponding adjacent inner surface of the base mount 210. In such embodiments, the linkage arm 230 may be freely displaceable at the medial attachment point 270 over a prescribed distance, which can be non- uniform in the direction along the longitudinal axis of the pin 272, relative to the “zero” position of the linkage arm 230. Thus, the restorative force is only imparted to the linkage arm 230 at the medial attachment point 270 after the linkage arm 230 is sufficiently deflected to contact one of the alignment rings 100.

[0066] The arrangement of the alignments rings 100 at the medial attachment point 270 described herein can be applied at the medial attachment points 270 of both of the linkage arms 230, 230A (see, e.g., FIGS. 2 through 7) of the engine support system 200 in any combination. By way of example, it is noted that the linkage arm 230 may be surrounded by alignment rings 100 of variable stiffness, while the linkage arm 230A may have gaps between alignment rings 100 of asymmetric thickness arranged on either side thereof. In some embodiments, alignment rings 100 may be installed at the medial attachment point 270 and/or at the inner attachment point of the linkage arm 230 and alignment rings 100 may be omitted either partially and/or entirely at the medial attachment point 270 and/or at the inner attachment point of the linkage arm 230A.

[0067] In the embodiment shown, the alignment rings 100 are arranged on opposite sides of the linkage arm 230 to occupy substantially all of the distance between the opposing inner surfaces of the base mount 210. Unlike in the direction L2 shown in FIG. 8, in which the length of the linkage arm 230 acts as a lever arm to apply a torque against the alignment rings 100 to allow the compression of the alignment rings 100 by the linkage arm 230 acting thereon, any force transmitted to the linkage arm 230 in the direction R3 (see, e.g., FIG. 7) would be applied to the linkage arm 230 at or adjacent the longitudinal axis of the linkage arm 230. This means that, in relation to the ability of the force transmitted to the linkage arm 230 to impart a torque that would cause a twisting motion of the linkage arm 230 at the inner attachment point 250A in the direction R3, the effective length of the linkage arm 230 is negligible and the torque that could be transmitted to the linkage arm 230 would require forces on the order of about ten times that of the forces in the R1 or R2 direction and would not be able to cause a significant rotation of the linkage arm 230 in the direction R3 that would compress beyond a negligible amount (e.g., 10% or less, 5% or less, 2% or less, 1% or less, etc.) any portion of the alignment rings 100. As such, the alignment rings 100 of the engine mount system 200 are configured to allow no, or only negligible, rotation of the linkage arm 100 relative to the base mount 100 about the longitudinal axis of the linkage arm 230 in the direction R3, while allowing movement, whether linear or rotational, of the linkage arm 230 relative to the base mount 210 in the directions R1 and R2, which are transversely oriented to the longitudinal axis of the linkage arm 230.

[0068] Other embodiments of the current invention will be apparent to those skilled in the art from a consideration of this specification or practice of the invention disclosed herein. Thus, the foregoing specification is considered merely exemplary of the current invention with the true scope thereof being defined by the following claims.

Claims

CLAIMS What is claimed is:

1. A system for attaching an aft portion of an aircraft engine to an aircraft structure, the system comprising: a base mount; a linkage arm that is arranged between opposing inner surfaces of the base mount and moveably attached to the base mount at least at one attachment point; a first alignment ring arranged between a first external surface of the linkage arm and a first inner surface of the opposing inner surfaces of the base mount; and a second alignment ring arranged between a second external surface of the linkage arm and a second inner surface of the opposing inner surfaces of the base mount; wherein the first external surface of the linkage arm is on an opposite side of the linkage arm from the second external surface of the linkage arm; and wherein the first and second alignment rings comprise an ultra-high temperature elastomeric material capable of operating at sustained temperatures of at least 500 °F (260 °C).

2. The system of claim 1, wherein the ultra-high temperature elastomeric material comprises silicone.

3. The system of claim 1, wherein the first and second alignment rings have a combined thickness that is greater than a combined distance between the first external surface of the linkage arm and the first inner surface of the base mount and between the second external surface of the linkage arm and the second inner surface of the base mount, such that the first and second alignment rings are precompressed between the linkage arm and the base mount.

4. The system of claim 1, wherein the first and second alignment rings are configured to allow a displacement of the linkage arm relative to the base mount about a longitudinal axis of the at least one attachment point.

5. The system of claim 4, wherein the first and second alignment rings are configured to allow a displacement of the linkage arm relative to the base mount in a plane defined by the longitudinal axis of the at least one attachment point and a longitudinal axis of the linkage arm.

6. The system of claim 5, wherein the first and second alignment rings are configured to substantially inhibit rotation of the linkage arm relative to the base mount about the longitudinal axis of the linkage arm.

7. The system of claim 1, configured such that at least portions of the first and second alignment rings undergo compression by movement of the linkage arm relative to the base mount, the compression of the first and second alignment rings causing a restorative force in a direction of a “zero”, or non-deflected, position of the linkage arm relative to the base mount.

8. The system of claim 1, wherein the at least one attachment point comprises a ball joint, about which the linkage arm is pivotable relative to the base mount, or a pin joint, along a length of which the linkage arm is linearly displaceable relative to the base mount.

9. The system of claim 1, wherein the at least one attachment point comprises an inner attachment point and a medial attachment point, the linkage arm being attached to the base mount at each of the inner attachment point and the medial attachment point.

10. The system of claim 9, wherein the inner attachment point comprises a ball j oint, about which the linkage arm is pivotable relative to the base mount, and wherein the medial attachment point comprises a pin joint, along a length of which the linkage arm is linearly displaceable relative to the base mount.

11. The system of claim 9, wherein the inner attachment point comprises a pin joint, along a length of which the linkage arm is linearly displaceable relative to the base mount, and wherein the medial attachment point comprises a ball joint, about which the linkage arm is pivotable relative to the base mount.

12. The system of claim 9, wherein both the inner and medial attachment points comprise a pin mount, along a length of which the linkage arm is linearly displaceable relative to the base mount.

13. The system of claim 9, wherein alignment rings are arranged on opposite sides of the linkage arm to separate the linkage arm from the base mount at both the inner and medial attachment points.

14. The system of claim 1, wherein at least one alignment ring has a nonlinear and/or noncontinuous spring force as a function of compression of the at least one alignment ring.

15. The system of claim 14, wherein the at least one alignment ring has voids, cavities, and/or notches formed in portion thereof to make the portion more susceptible to compression than other portions of the at least one alignment ring.

16. The system of claim 1, wherein one or more further alignment rings are arranged, along with the first and/or second alignment rings, between the linkage arm and the base mount.

17. The system of claim 16, wherein the first and/or second alignment rings and the one or more further alignment rings have different stiffness values.

18. The system of claim 16, wherein each of the first alignment ring and/or the second alignment ring and the one or more further alignment rings have different stiffness values.

19. The system of claim 1, wherein the first alignment ring has a different stiffness from a stiffness of the second alignment ring, such that a force and/or torque necessary to cause a movement of the linkage arm towards the base mount in a direction of the first alignment ring is not the same as a force and/or torque necessary to cause the movement of the linkage arm towards the base mount in a direction of the second alignment ring, wherein the movement of the linkage arm towards the base mount in the direction of the first alignment ring is a same magnitude as the movement of the linkage arm towards the base mount in the direction of the second alignment ring.

20. The system of claim 1, wherein the first and second alignment rings are non-metallic, such that, upon failure, the first and/or second alignment rings are configured to disintegrate and be burned by exhaust from the aircraft engine so as to not impair operation of any other components of the aircraft engine upon such failure.