CN210164506U - Fan rotor support system and fan rotor rear bearing assembly thereof - Google Patents

Abstract

An object of the utility model is to provide a bearing assembly behind fan rotor, including the rear bearing and with the support piece that the rear bearing is connected to the fan shaft, the rear bearing is used for setting up between support piece and medium machine casket, this bearing assembly behind fan rotor includes the energy-absorbing pad, the energy-absorbing pad sets up between rear bearing and support piece to all adopt the cooperation of the drum-shaped face of radial outside salient with the inner circle of rear bearing and with support piece's outer lane. The utility model also provides a fan rotor braced system of bearing assembly behind the above-mentioned fan rotor. The utility model provides a deloading design under FBO incident.

Description

Fan rotor support system and fan rotor rear bearing assembly thereof

Technical Field

The utility model relates to an aeroengine especially relates to an aeroengine's fan rotor braced system.

Background

According to the requirements of airworthiness regulations (FAR33.74, FAR33.94), commercial aircraft engines must ensure that the occurrence of FBO events does not lead to catastrophic consequences. In order to ensure the safety of the aircraft engine after an FBO event occurs, the conventional method is to increase the structural strength of each component on the force transmission path of the engine, such as a rotor support structure, a bearing casing, an installation system and the like, and increase the stress reserve margin of the engine so as to ensure that key components cannot be damaged under the FBO load. However, this results in an increased weight of the engine, which is disadvantageous for weight-saving design.

In recent years, as engine thrust increases, fan blade diameters have increased, and imbalance loads from FBO events have also increased. In order to ensure that an FBO event does not cause catastrophic consequences without significantly increasing the weight of the engine, a load relief design is generally used to reduce the FBO limit load borne by critical components of the engine, thereby ensuring the safety of the engine. A common load relief design is also called a fusing design, and means that a component capable of failing is designed to fuse under the FBO load, so that on one hand, the critical rotating speed of the rotor is reduced, the rotor is in a supercritical rotating speed state, and the unbalanced load is reduced; and on the other hand, the transmission path of the FBO load to the stator casing is changed, so that the FBO load is redistributed to reduce the FBO load transmitted to the key component.

A common fusing design, for example, see US6447248, is to provide a thinned section on the conical wall of the front bearing as a mechanically weak component, so that it fails under a predetermined load (threshold), changing the dynamics and force transmission path of the engine, reducing the unbalanced load transmitted to the intermediate casing through the bearing and its mounting, etc., and avoiding the destruction of other critical components of the engine. However, after the first fusing component fails, the bending moment of the low-pressure rotating shaft at the rear bearing is too large, stress concentration is easily generated, and the rotating shaft is damaged or even broken.

Therefore, a related fusing design is required near the rear bearing to avoid the excessive stress concentration generated by the fan shaft and ensure the safety of the engine.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a deloading design under FBO incident.

The utility model provides a bearing assembly behind fan rotor, include the rear bearing and will the rear bearing is connected to the support piece of fan shaft, the rear bearing is used for setting up between support piece and the medium machine casket, this bearing assembly includes the energy-absorbing pad behind the fan rotor, the energy-absorbing pad set up in the rear bearing with between the support piece, and with the inner circle of rear bearing and with the outer lane of support piece all adopts the drum-shaped face cooperation of radial outside salient.

In one embodiment, the energy absorbing pad is comprised of an elastomeric damping structure.

In one embodiment, the energy absorbing pad is comprised of an elastomeric damping structure with an elastomeric support disposed therein.

In one embodiment, the resilient mount is configured to fail under a predetermined load.

In one embodiment, the resilient mount comprises a plurality of fork mounts.

In one embodiment, projections of the energy absorption pad, the inner ring of the rear bearing and a drum-shaped surface matched with the outer ring of the support on a longitudinal section passing through an axial center line are all arc sections.

In one embodiment, projections of the energy absorbing pad and the inner ring of the rear bearing and a drum-shaped surface matched with the outer ring of the support on a longitudinal section passing through an axial center line are two concentric circular arc sections.

In one embodiment, the support is integrally formed with the fan shaft.

The utility model also provides a fan rotor braced system, bearing assembly behind foretell fan rotor.

In one embodiment, the fan rotor support system further comprises a forward bearing assembly by which the fan rotor is supported to the intermediate casing and a rear bearing assembly, the forward bearing assembly comprising a forward bearing and a support cone wall connecting the forward bearing to the intermediate casing, the support cone wall having a fuse site, the fuse site failing at a predetermined load.

After the FBO event is started, the first fusing part near the front bearing fails under the action of unbalanced load, the constraint of the fan rotor at the front bearing is released, the swing radius of the front end of the fan rotor is increased, pitching deformation is generated, and huge unbalanced moment is generated on the adjacent rear bearing. This can lead to large local bending deformations and stress concentrations at the rear bearing of the fan shaft, causing damage or even breakage of the shaft, with catastrophic consequences. The fan rotor supporting system or the bearing supporting structure can avoid the concentration of excessive stress of the fan shaft.

After the FBO event happens, the pitching constraint of the fan shaft at the rear bearing is released by the spherical damping fusing mechanism at the rear bearing, and the phenomenon that the fan shaft is damaged due to stress concentration at the rear bearing because the swinging radius of the fan rotor is increased after the fusing part of the supporting conical wall serving as the primary fusing part is failed is avoided. In the spherical damping fuse mechanism at the rear bearing, the damping energy absorption structure plays a role, so that FBO energy can be further consumed, and loads transmitted to key components such as an intermediate casing and the like are reduced. On the basis of the primary fusing design, a spherical damping fusing mechanism is designed at the rear bearing to serve as a secondary fusing component, so that the safety of the engine structure under the FBO load is guaranteed, the FBO load is reduced, the design difficulty is reduced, and the design reliability is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIG. 1 is an exemplary configuration of a turbofan engine interior in which a fan rotor support system according to the present invention is employed.

FIG. 2 is an example configuration of a fan rotor support system.

Fig. 3 is a partially enlarged view of the vicinity of the area indicated by a in fig. 2.

Detailed Description

The present invention will be further described with reference to the following detailed description and the accompanying drawings, wherein the following description sets forth more details for the purpose of providing a thorough understanding of the present invention, but it is obvious that the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar generalizations and deductions based on the practical application without departing from the spirit of the present invention, and therefore, the scope of the present invention should not be limited by the contents of the detailed description.

For example, a first feature described later in the specification may be formed over or on a second feature, and may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Additionally, reference numerals and/or letters may be repeated in the various examples throughout this disclosure. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, when a first element is described as being coupled or coupled to a second element, the description includes embodiments in which the first and second elements are directly coupled or coupled to each other, as well as embodiments in which one or more additional intervening elements are added to indirectly couple or couple the first and second elements to each other.

As used herein, the terms "a", "an" and/or "the" are not to be construed as limiting the singular, but rather are intended to include the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary words "below" and "beneath" can encompass both an orientation of up and down. The device may have other orientations (rotated 90 degrees or at other orientations) and the spatial relationship descriptors used herein should be interpreted accordingly. Further, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

It should be noted that these and other figures are given by way of example only and are not drawn to scale, and should not be construed as limiting the scope of the invention as it is actually claimed. Further, the conversion methods in the different embodiments may be appropriately combined.

The aircraft engine can be configured into a high-pressure double-rotor system and a low-pressure double-rotor system. For example, the low pressure rotor may be typically supported by a # 1 bearing, a # 2 bearing, and a # 5 bearing, wherein the # 1 bearing and the # 5 bearing may be roller bearings and the # 2 bearing may be ball bearings. The following description will be given taking a low-pressure rotor as an example, and only the support structures of the bearing # 1 and the bearing # 2 are shown.

Fig. 1 shows a front end portion of a turbofan engine 100 as an example of an aircraft engine. In fig. 1, a turbofan engine 100 is shown to include a fan rotor 20, a middle case 30, and the like. Turbofan engine 100 also includes a fan rotor support system 10, described in detail below, with fan rotor 20 rotatably coupled to intermediate case 30 via fan rotor support system 10 and intermediate case 30 coupled to the fan case such that fan rotor 20 may be rotatably supported by either intermediate case 30 or the fan case. In fig. 1, air is taken in from the left side and air is discharged from the right side. The axial centerline L0 of turbofan engine 100 or fan rotor 20 is shown, and the overall structure may be rotationally symmetric about axial centerline L0, i.e., the overall structure may be a solid structure rotated about axial centerline L0 from the configuration shown in FIG. 1. The cross-sections shown in fig. 1 and later fig. 2 and 3 may each be referred to as longitudinal cross-sections taken along an axial centerline L0 of the fan rotor 20.

Hereinafter, for convenience of description, a direction parallel to the axial center line L0 of the fan rotor 20 is referred to as an axial direction, a direction along the radial direction of the fan rotor 20 is referred to as a radial direction, and a direction along the circumferential direction of the fan rotor 20 is referred to as a circumferential direction.

The terms "along a predetermined direction" and "in a predetermined direction" include directions having a component in the predetermined direction, that is, the directions may be inclined with respect to the predetermined direction but may not be perpendicular to each other. "parallel" may refer to exact parallel where the intersection angle between two directions is zero, or may refer to approximate parallel where the intersection angle between two directions is within a certain range, for example, within 10 degrees, and "perpendicular" may refer to exact perpendicular where the intersection angle between two directions is 90 degrees, or may refer to approximate perpendicular where the intersection angle between two directions is within a certain range, for example, within 10 degrees, from 90 degrees.

Also, the terms "upstream," "front," "downstream," or "rear" are used hereinafter with respect to the intake direction of the engine, with "upstream" or "front" being closer to the intake end of the engine and "downstream" or "rear" being closer to the exhaust end of the engine.

The fan rotor 20 includes an inlet cone 201 along which gas is introduced. The fan rotor 20 also includes a fan shaft 202 and fan blades 203 mounted to the fan shaft 202. The fan shaft 202 of the fan rotor 20 is connected to the intermediate casing 30 by the fan rotor support system 10.

The fan rotor support system 10 includes a forward bearing assembly 1 and an aft bearing assembly 2, i.e., the fan shaft 202 of the fan rotor 20 is supported to the intermediate casing 30 by the forward bearing assembly 1 and the aft bearing assembly 2, or it can be stated that the forward bearing assembly 1 and the aft bearing assembly 2 support the fan rotor 20 to the intermediate casing 30 so that the fan shaft 202 can rotate relative to the intermediate casing 30, thereby rotating the fan blades 203 mounted on the fan shaft 202. In the illustrated embodiment, the front bearing assembly 1 is closer to the intake front end than the rear bearing assembly 2.

Referring to fig. 2, the front bearing assembly 1 includes a front bearing 3. The front bearing 3 may also be referred to as a # 1 bearing, for example a roller bearing may be used to provide radial constraint to the fan shaft 202. The front bearing assembly 1 further comprises a supporting cone wall 5, the supporting cone wall 5 connecting the front bearing 3 to an intermediate casing 30 (shown in fig. 1).

The supporting cone wall 5, extending in the radial direction, connects the front bearing 3 to the intermediate casing 30 and is the important path for the fan rotor load to be transferred to the intermediate casing 30. The supporting cone wall 5 has a fuse portion 51, and the fuse portion 51 may fail under a predetermined load and thus may fail under an FBO load, and the fuse portion 51 may be referred to as a primary fuse member. The supporting conical wall 5 may be a rigid component, and the fusing part 51 is a weak part of the supporting conical wall 5, for example, the fusing part 51 may be a part with a reduced thickness as the supporting conical wall 5, that is, the fusing part 51 realizes fusing effect by reducing the thickness. In fact, the fusing point 51 may be formed in any weak structural configuration, for example, the fusing point 51 may be formed by using a material with lower strength. The fusing portions 51 may be distributed continuously or discontinuously along the circumferential direction, as long as the fusing portions 51 can be fused and fail under the FBO load.

Referring to fig. 3, fig. 3 shows a partially enlarged view of the vicinity of the region circled by the reference character a in fig. 2. The rear bearing assembly 2 comprises a rear bearing 4. The aft bearing 4 may also be referred to as a # 2 bearing, and may be implemented, for example, as a ball bearing, providing both axial and radial constraint to the fan shaft 202.

The rear bearing assembly 2 further comprises a support 205. The support 205 connects the rear bearing 4 to the fan shaft 202 of the fan rotor 20, the rear bearing 4 being arranged between the support 205 and the intermediate case 30. In the illustrated embodiment, the support 205 is integrally formed with the fan shaft 202, or alternatively, the support 205 may be referred to as a fan extension shaft that is coupled to the intermediate case 30 by the rear bearing 4.

The rear bearing assembly 2 further comprises an energy absorbing pad 6. The energy absorbing pad 6 is arranged between the rear bearing 4 and the support 205 and is fitted with a radially outwardly protruding drum-shaped surface both with the inner ring 41 of the rear bearing 4 and with the outer ring 206 of the support 205. In other words, the inner ring 41 of the rear bearing 4 is a concave toroidal surface with respect to the main body of the rear bearing 4, i.e. protrudes radially outwards with respect to the fan shaft 202 or the fan rotor 20; the outer ring 206 of the support member 205 is an outer toroidal surface with respect to the main body of the support member 205, i.e. projects radially outwards with respect to the fan rotor 20; the radially outer surface 63 of the energy-absorbing pad 6 cooperating with the rear bearing 4 is a convex torus with respect to the main body of the energy-absorbing pad 6, i.e. protrudes radially outwards for the fan rotor 20, while the radially inner surface 64 of the energy-absorbing pad 6 cooperating with the support member 205 is a concave torus with respect to the main body of the energy-absorbing pad 6, i.e. protrudes radially outwards for the fan rotor 20. By the energy absorbing pad 6 being fitted with the inner ring 41 of the rear bearing 4 and with the outer ring 206 of the support 205 both with radially outwardly protruding crowning, the support 205 or the fan shaft 202 or the fan rotor 20 can slide relatively along the fitted crowning within a certain range, thereby releasing to a certain extent the pitch and twist constraints of the fan shaft 202 or the fan rotor 20 at the rear bearing 4.

In the illustrated embodiment, the projections of the drum-shaped surfaces of the energy absorbing pad 6, the inner ring 41 of the rear bearing 4 and the outer ring 206 of the support 205 on the illustrated cross section (or the longitudinal section passing through the axial center line L0 as mentioned above) are arc segments, which can also be called as a spherical damping fusing mechanism, so that the relative sliding of the support 205 or the fan rotor 20 along the drum-shaped surfaces can be smoother. Further, the projections of the drum-shaped surfaces of the energy absorbing pad 6 cooperating with the inner ring 41 of the rear bearing 4 and with the outer ring 206 of the support 205 on a central cross section passing through the axial center line L0 may be two concentric circular arc segments. The spherical damping fusing mechanism can partially release the pitching and bending rigidity of the rear bearing after an FBO event occurs, and simultaneously absorb certain energy to protect the safety of the rotating shaft.

The energy absorbing pad 6 may be constituted by an elastic damping structure 61. In the illustrated embodiment, the energy absorbing pad 6 is formed by an elastic damping structure 61 in which an elastic support 62 is arranged. That is, the elastic damping structure 61 and the elastic support 62 together constitute the energy absorbing pad 6.

The resilient mount 62 may also fail under a predetermined load. The predetermined load to deactivate the resilient support 62 may or may not be equal to the predetermined load to deactivate the fuse portion 51. For example, a fugitive notch is preformed in the resilient mount 62 to allow it to fail under FBO loading. In the illustrated embodiment, the resilient mount 62 includes a plurality of fork mounts. That is, the elastic damping structure 61 and the elastic support 62 together form the fail-able energy absorption pad 6, which may be referred to as a secondary fuse component. In the case of providing the resilient support 62 which is deactivatable under a predetermined load, it may be essential that the resilient support 62 initially acts as a support between the rear bearing 4 and the support 205, in which case the resilient support 62 may secure the rear bearing 4 to the support 205, and that only the resilient damping structure 61 is acting as a support between the rear bearing 4 and the support 205 after the resilient support 62 has been deactivated under the predetermined load.

When the engine normally works, the rigidity of the supporting conical wall 5 near the front bearing 3 of the front bearing assembly 1 is enough, and the outer ring 206 of the supporting piece 205 near the rear bearing 4 of the rear bearing assembly 2 is fixedly connected with the inner ring 41 of the rear bearing 4 through the elastic bracket 62, so that the fan shaft 202 can be normally supported, and the fan rotor 20 can be ensured to normally work.

After the FBO event occurs, the fan rotor 20 generates significant impact and imbalance loads. The fusing point 51 on the supporting cone wall 5 supporting the front bearing 3 is disabled, and the elastic support 62 between the inner ring 41 of the rear bearing 4 and the outer ring 206 of the support 205 is disabled at the pre-notched position. At this time, only the elastic damping structure 61 is left between the outer ring 206 of the supporting member 205 and the inner ring 41 of the rear bearing 4, so that the fan shaft 202 can relatively slide along the drum surface within a certain range, the pitch and torsion constraints of the fan shaft at the rear bearing 4 are released, and the fan rotor 20 is prevented from increasing in swing radius after the fusing part 51 fails, and the fan shaft 202 generates excessive stress concentration at the rear bearing 4.

In the preferred embodiment, the fan rotor support system 10 described above, the fan shaft is connected to the inner ring of the # 2 bearing via an extension shaft in the vicinity of the # 2 bearing, and further connected to the stator member such as the intermediate casing via the # 2 bearing. The extending shaft and the 2# bearing inner ring are correspondingly provided with convex spherical surfaces, correspondingly, the 2# bearing inner ring is correspondingly provided with concave spherical surfaces, and a certain radial gap is formed between the convex spherical surfaces on the extending shaft and the concave spherical surfaces on the 2# bearing inner ring. A radial gap between a convex spherical surface on the extension shaft and a concave spherical surface on the 2# bearing inner ring is provided with an elastic support and a damping structure which jointly form a failure energy absorption pad. On the elastic bracket, easy gaps are prefabricated, and the elastic bracket can fail under the load of the FBO. Therefore, when the engine works normally, the relative motion between the extension shaft and the No. 2 bearing inner ring is restrained due to the function of the inefficacy energy absorption pad formed by the elastic support and the damping structure. Through the constraint, the fan shaft and the 2# bearing cannot slide relatively when the engine works normally. After the FBO incident takes place, fan rotor produces huge unbalanced load, and prefabricated breach is invalid according to the predetermined mode under the FBO load on the elastic support, makes 2# bearing inner race and extension axle top can follow the sphere relative slip, forms the ball pivot and connects, avoids first fusing part to lose efficacy after, fan rotor swing radius increase, and the fan shaft produces too big stress concentration in 2# bearing department. Under the action of huge FBO load, the prefabricated notch on the elastic support fails, the inner ring of the 2# bearing and the top of the extension shaft slide relatively along the spherical surface, and the internal damping energy-absorbing structure is extruded, so that the FBO energy is further consumed, and the load transmitted to key components such as an intermediary casing and the like is reduced.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can understand the changes or substitutions within the technical scope of the present invention, and the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A fan rotor rear bearing assembly comprising a rear bearing and a support connecting the rear bearing to a fan shaft, the rear bearing being arranged between the support and a middle casing, characterised in that the fan rotor rear bearing assembly comprises an energy absorbing pad arranged between the rear bearing and the support and cooperating with both the inner race of the rear bearing and the outer race of the support with radially outwardly projecting drum-shaped faces.

2. The fan rotor rear bearing assembly of claim 1,

the energy-absorbing pad is composed of an elastic damping structure.

3. The fan rotor rear bearing assembly of claim 1,

the energy-absorbing pad is formed by arranging an elastic support in an elastic damping structure.

4. The fan rotor rear bearing assembly of claim 3,

the resilient mount is configured to fail under a predetermined load.

5. The fan rotor rear bearing assembly of claim 3,

the resilient mount comprises a plurality of fork mounts.

6. The fan rotor rear bearing assembly of claim 1,

projections of the energy absorption pad, the inner ring of the rear bearing and a drum-shaped surface matched with the outer ring of the support piece on a longitudinal section passing through an axial center line are all arc sections.

7. The fan rotor rear bearing assembly of claim 1,

the projections of the energy absorption pad, the inner ring of the rear bearing and the drum-shaped surface matched with the outer ring of the support piece on a longitudinal section passing through an axial center line are two concentric arc sections.

8. The fan rotor rear bearing assembly of claim 1,

the support is integrally formed with the fan shaft.

9. A fan rotor support system, characterized in that,

comprising a fan rotor rear bearing assembly as claimed in any one of claims 1 to 8.

10. The fan rotor support system of claim 9, further comprising a forward bearing assembly,

the fan rotor is supported to the intermediate casing by means of said front bearing assembly and said rear bearing assembly, said front bearing assembly comprising a front bearing and a supporting conical wall connecting said front bearing to said intermediate casing,

the support cone wall has a fuse portion that fails under a predetermined load.

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