Half-splitting type spherical oil film ferrule structure suitable for aero-engine fulcrum damping design

Abstract

The invention provides a split-half type spherical oil film ferrule structure suitable for aero-engine fulcrum damping design. The split-half type spherical oil film ferrule structure comprises an inner ferrule, an outer ferrule, a front piston ring, a rear piston ring, a front metal rubber ring and a rear metal rubber ring. The outer ring surface of the inner ferrule and the inner ring surface of the outer ferrule are ellipsoid surfaces, a spherical radial gap is formed between the inner ferrule and the outer ferrule, and the front piston ring and the rear piston ring seal the end faces of the spherical radial gap. The split-half type spherical oil film ferrule structure is installed between a bearing outer ring and a bearing seat, a spherical oil film layer can be formed in a spherical radial gap when an engine works, oil film damping is provided for a fulcrum, and meanwhile a metal rubber ring is added to improve the damping effect. By adopting the spherical oil film ferrule structure, the problems of ferrule local clamping stagnation and oil film failure of a traditional annular oil film ferrule during high-speed rotation of a rotor and angular deformation of a shaft neck are solved, and the damping performance and the working application range of the non-centering extrusion oil film damper are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of damping and vibration reduction design of a support structure of an aero-engine high-speed rotor system, and in particular relates to a semi-spherical oil film ring structure suitable for aero-engine fulcrum damping design. Background Art

[0002] According to the squeeze film theory, when the space between two parallel plates is filled with liquid and approaches each other at a certain speed, a certain pressure will be generated between the two plates; when the two plates move relative to each other at a certain frequency and amplitude, oil film damping will be generated to absorb the motion energy to achieve vibration reduction. The squeeze film damper vibration reduction technology developed based on this theory is hailed as a milestone in the history of rotating machinery development and has been widely used in high-speed rotating machinery such as aircraft engines. Squeeze film dampers can be divided into centering structures and non-centering structures according to different structural forms. Among them, non-centering squeeze film dampers are used in rotor systems without centering elastic support structures. The oil film is usually located between the outer ring of the bearing and the rigid bearing seat, and the two form the inner and outer rings of the oil film. In the non-working state, the rotor journal and the inner ring of the oil film are statically eccentric due to gravity, and the gap on the lower side of the oil film is small and the gap on the upper side is large; in the working state, the rotor journal and the inner ring of the oil film precess, and then the oil film is squeezed to generate oil film force to "lift" the inner ring of the oil film, and at the same time, oil film damping is generated to consume vibration energy to achieve rotor vibration reduction. Compared with the centered oil film, the non-centered squeeze film damper has a simpler structure and occupies less space. Therefore, it can be used in the rotor system fulcrum damping and vibration reduction design of small-sized aircraft engines such as turboshaft engines.

[0003] For non-centering squeeze film dampers, due to the lack of elastic centering structure, when the rotor vibration is too large and the precession radius of the oil film inner ring exceeds the oil film gap, the outer ring of the bearing will directly press on the bearing seat, which will cause the oil film failure problem and seriously affect the damping performance of the squeeze film damper. Therefore, it is usually necessary to control the eccentricity below 0.3 in design and use. However, the operating speed and workload of modern advanced aircraft engines are constantly increasing. The rotor system often needs to pass through multiple critical speeds, especially the pitch and bending critical speeds. The precession form of the rotor journal is not only radial eccentricity, but also angular tilt, which in turn drives the outer ring of the bearing (i.e., the inner ring of the oil film) to deflect, and its end is in contact with the bearing seat, causing local failure of the oil film and damaging the damping performance of the oil film.

[0004] Reference Figure 4aThe non-centering squeeze film damper with a traditional annular oil film ring is used at the pivot position of the aircraft engine rotor system. Its typical structure includes a pivot bearing 12, a rigid bearing seat 13, an annular oil film ring 14, an expansion ring 15, a baffle 16 and a bolt connector 17. The annular oil film ring 14 is installed on the bearing outer ring 121 of the pivot bearing 12, the expansion ring 15 is installed at the front end of the annular oil film ring 14, and the baffle 16 is connected to the rigid bearing seat 13 through a bolt connector 17 to prevent the expansion ring 15 and the annular oil film ring 14 from axial movement. The rigid bearing seat 13 has an axial oil hole 131 and a radial oil hole 132, and an annular radial gap 18 is formed between the inner ring surface 133 of the rigid bearing seat 13 and the outer ring surface 141 of the annular oil film ring 14.

[0005] Reference Figure 4a and Figure 5a During the operation of the engine, the lubricating oil passes through the axial oil hole 131 and the radial oil hole 132 of the rigid bearing seat 13 and enters the annular radial gap 18, forming an annular oil film to provide damping for the rotor fulcrum. However, when the rotor rotates, the rotor journal 20 will deform angularly, causing the fulcrum bearing 12 and the annular oil film ring 14 to tilt, thereby causing the gap value of the annular radial gap 18 to change and no longer be evenly distributed along the axial direction. In addition, the annular oil film ring 14 will have an excessively large gap at its front end 181, weakening the damping effect of the oil film. At the same time, it will partially contact with the rigid bearing seat 13 at the rear end 182 to form a jam, which will seriously damage the damping performance of the oil film.

[0006] At present, the angular inclination of the rotor journal causes the end of the inner ring of the oil film to contact the outer ring of the oil film. The resulting local failure of the oil film has seriously restricted the application and development of non-centering squeeze film dampers. Summary of the invention

[0007] In order to overcome the above technical problems, the present invention provides a semi-spherical oil film ring structure suitable for the design of aircraft engine fulcrum damping, which can adapt to the angular deformation of the rotor shaft neck when the rotor runs at high speed and maintain a stable oil film thickness. The non-centering squeeze oil film damper can maintain stable damping performance and has a simple structure and is easy to disassemble and assemble.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A half-spherical oil film ring structure suitable for the design of aero-engine pivot damping includes an inner ring, an outer ring, a front expansion ring, a rear expansion ring, a front metal rubber ring and a rear metal rubber ring. The front end of the outer ring is provided with a front mounting hole, in which the front expansion ring and the front metal rubber ring can be installed; the rear end of the outer ring is provided with a rear mounting hole, in which the rear expansion ring and the rear metal rubber ring can be installed.

[0010] The outer ring is a half-structure, consisting of an upper ring and a lower ring, which is convenient for assembly and disassembly of the components, and radial oil holes are opened on the outer ring.

[0011] The outer ring surface of the inner ring and the inner ring surface of the outer ring are both ellipsoidal surfaces, forming a spherical radial gap between the two, and the front expansion ring and the rear expansion ring seal the end surface of the spherical radial gap.

[0012] The materials used for the front metal rubber ring and the rear metal rubber ring are both metal rubber materials, which are microstructure functional metal materials made by winding metal wires into spiral coils and undergoing weaving, molding and post-processing processes.

[0013] Furthermore, the curvature radius of the outer ring surface of the inner ring on the cross section is set to R1, and the curvature radius of the inner ring surface of the outer ring on the cross section is R2, then the clearance value of the spherical radial clearance can be expressed as Δ = (R2 - R1). The curvature radius of the spherical radial clearance on the cross section can be expressed as R3 = (R2 + R1) / 2. In the radial direction, the radius of the spherical radial clearance is r, and the relationship between the two generally satisfies R3 ≈ (1.0~1.5)·r. The specific value can be optimized according to actual needs.

[0014] Furthermore, the half-spherical oil film ring structure suitable for the design of aero-engine pivot damping is installed between the outer ring of the pivot bearing and the rigid bearing seat, the radial oil holes on the outer ring are aligned with the radial oil holes on the rigid bearing seat, and the lubricating oil enters the spherical radial gap between the outer ring and the inner ring through the axial oil holes and radial oil holes of the bearing seat and the radial oil holes on the outer ring in turn to form a spherical oil film, and the front expansion ring and the rear expansion ring seal the end face of the spherical radial gap to prevent the lubricating oil from leaking. The baffle is installed on the rigid bearing seat through a bolted connector and axially presses the front metal rubber ring to prevent the oil film ring structure from moving.

[0015] The beneficial effects of the present invention compared with the prior art are:

[0016] The half-spherical oil film ring structure suitable for the aircraft engine pivot damping design of the present invention can generate a spherical oil film inside the spherical radial clearance to provide oil film damping for the rotor pivot, and when the rotor shaft neck undergoes angular deformation, causing the pivot bearing and the inner ring to tilt, the spherical radial clearance can maintain a stable clearance value and oil film thickness, avoiding the local contact jamming problem that occurs when the traditional annular oil film ring rotor is angularly deformed, thereby improving the damping performance and working application range of the non-centering squeeze oil film damper.

[0017] The front metal rubber ring and the rear metal rubber ring are made of metal wire through weaving, molding and post-processing processes. They not only have high-strength characteristics similar to the selected metal material, but also can produce a high damping effect through the internal friction of the metal wire. By changing the length and width of the metal wire and the processing conditions, the elastic modulus and material loss factor of the metal rubber can be adjusted, and finally the mechanical characteristics of low stiffness and high damping can be achieved. When the rotor journal undergoes angular deformation, the outer ring of the bearing will radially squeeze the metal rubber ring at the end, producing a certain damping effect, which helps to improve the vibration reduction performance of the damper.

[0018] The semi-spherical oil film ring structure does not require a complex oil circuit structure or occupy more space, has lower design, processing and assembly costs, and can be applied to the damping and vibration reduction design of the support structure of a small-sized aircraft engine high-speed rotor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1a It is a 3 / 4 cross-sectional view and a partially enlarged structural schematic diagram of the cross-sectional surface of a half-spherical oil film ring structure suitable for a non-centering squeeze film damper of the present invention;

[0020] Figure 1b This is the exploded view of the ring structure parts;

[0021] Figure 2a It is a schematic diagram of the partially enlarged structure of a single-side cross section of the outer ring;

[0022] Figure 2b It is a schematic diagram of the partially enlarged structure of a single-side cross section of the inner ring;

[0023] Figure 3 It is a schematic diagram for marking the radius of curvature of the spherical surface of the ferrule;

[0024] Figure 4a A typical structural diagram of a non-centering squeeze film damper of an aircraft engine rotor-support structure system using a traditional oil film ring;

[0025] Figure 4b It is a structural schematic diagram of a half-spherical oil film ring structure suitable for a non-centering squeeze film damper adopting the present invention;

[0026] Figure 5a It is a schematic diagram of the structural deformation of the non-centering squeeze film damper of the rotor-support structure system of an aircraft engine when the rotor journal is deformed angularly using a traditional oil film ring;

[0027] Figure 5b The schematic diagram is a structural diagram of the distributed spherical oil film ring structure of the present invention applicable to the non-centering squeeze film damper when the rotor journal is angularly deformed.

[0028] The accompanying drawings are marked as: inner ring 1, outer ring 2, inner annular surface 21, front mounting hole 22, rear mounting hole 23, upper half ring 26, lower half ring 27, upper radial oil hole 28, lower radial oil hole 29, front expansion ring 3, rear expansion ring 4, front metal rubber ring 5, rear metal rubber ring 6, spherical radial gap 7, spherical oil film ring structure 10, outer annular surface 11, fulcrum bearing 12, bearing outer ring 121, rigid bearing seat 13, annular oil film ring 14, outer annular surface 141, expansion ring 15, baffle 16, bolt connection 17, annular radial gap 18, rotor journal 20, front end 181, rear end 182, axial oil hole 131, radial oil hole 132, end 1211, inner annular surface 133. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned purpose, the present invention adopts the following technical scheme.

[0030] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0031] Reference Figure 1a and Figure 1b The present invention discloses a half-spherical oil film ring structure 10 suitable for the design of aero-engine pivot damping, comprising an inner ring 1, an outer ring 2, a front expansion ring 3, a rear expansion ring 4, a front metal rubber ring 5 and a rear metal rubber ring 6. The inner ring 1 is located inside the outer ring 2, and the outer ring 2 is a half-structure, consisting of an upper half ring 26 and a lower half ring 27, with an upper radial oil hole 28 and a lower radial oil hole 29 respectively opened in the middle. The materials used for the front metal rubber ring 5 and the rear metal rubber ring 6 are both metal rubber materials, which are microscopically functional metal materials made by winding metal wire into a spiral roll, weaving and molding.

[0032] Reference Figure 1a , Figure 2a and Figure 2b, the front end of the outer ring 2 has a front mounting hole 22, which can be installed with the front expansion ring 3 and the front metal rubber ring 5, and the rear end of the outer ring 2 has a rear mounting hole 23, which can be installed with the rear expansion ring 4 and the rear metal rubber ring 6. The outer ring surface 11 of the inner ring 1 and the inner ring surface 21 of the outer ring 2 are both ellipsoidal surfaces, forming a spherical radial gap 7 between the two, and the front expansion ring 3 and the rear expansion ring 4 seal the spherical radial gap 7 at the end face. Assuming that the curvature radius of the outer ring surface 11 of the inner ring 1 on the cross section is R1, and the curvature radius of the inner ring surface 21 of the outer ring 2 on the cross section is R2, the gap value of the spherical radial gap 7 can be expressed as Δ = (R2- R1).

[0033] Reference Figure 2a , Figure 2b and Figure 3 A half-spherical oil film ring structure 10 suitable for the design of aero-engine fulcrum damping of the present invention has a spherical radial gap 7, and its curvature radius can be expressed as R3 = (R2 + R1) / 2. In the radial direction, the radius of the spherical radial gap 7 is r, and the two generally satisfy the relationship R3 ≈ (1.0~1.5)·r. The specific value can be optimized and designed according to actual needs.

[0034] Reference Figure 4b The half-spherical oil film ring structure 10 of the present invention suitable for the non-centering squeeze film damper is used to replace the pivot point of the rotor system of the aircraft engine. Figure 4a The annular oil film ring 14 in the bearing is shown in FIG. The inner ring 1 is mounted on the outer ring 121 of the bearing, the outer ring 2 is mounted in the rigid bearing seat 13, the upper radial oil hole 28 on the outer ring 2 is aligned with the radial oil hole 132 on the rigid bearing seat 13, and the baffle 16 axially presses the front metal rubber ring 5 to prevent the oil film ring structure 10 from moving. A spherical radial gap 7 is formed between the outer ring surface 11 of the inner ring 1 and the inner ring surface 21 of the outer ring 2.

[0035] Reference Figure 1a , Figure 4b and Figure 5b , the half-spherical oil film ring structure 10 suitable for the non-centering squeeze film damper of the present invention is adopted to replace Figure 4aThe annular oil film ring 14 in the engine, during the operation of the engine, the lubricating oil passes through the axial oil hole 131, the radial oil hole 132 on the rigid bearing seat 13 and the upper radial oil hole 28 on the outer ring 2 in turn to enter the spherical radial gap 7, forming a spherical oil film to provide damping for the rotor fulcrum. The front expansion ring 3 and the rear expansion ring 4 seal the spherical radial gap 7 at the end to prevent the lubricating oil from leaking. When the rotor rotates, the rotor journal 20 undergoes angular deformation, causing the fulcrum bearing 12 and the inner ring 1 to tilt. At this time, the gap value of the spherical radial gap 7 does not change significantly. In addition, the front metal rubber ring 5 and the rear metal rubber ring 6 have the mechanical characteristics of low stiffness and high damping. When the rotor journal 20 undergoes angular deformation, the outer ring 121 of the bearing will radially squeeze the rear metal rubber ring 6 at its end 1211, which will also produce a certain damping effect.

[0036] The semi-spherical oil film ring structure 10 suitable for the non-centering squeeze film damper comprises an inner ring 1 and an outer ring 2 with a spherical surface, a spherical radial gap 7 is formed between the two and a spherical oil film is generated, which can adapt to the angular deformation of the shaft neck during the operation of the rotor, maintain a stable oil film thickness, and thus improve the damping performance of the non-centering squeeze film damper. It does not require a complex oil circuit structure, has a lower design, processing and assembly cost, and can be applied to the damping and vibration reduction design of a high-speed rotor system of a small-sized aircraft engine.

[0037] The half-spherical oil film ring structure 10 suitable for the non-centering squeeze oil film damper forms a spherical oil film inside the spherical radial gap 7. The curvature radius R3 of the spherical radial gap 7 is a parameter to be designed. By modifying the curvature radius value, the spherical oil film structure can be adjusted to adapt to different degrees of angular deformation of the rotor journal 20.

[0038] The front metal rubber ring 5 and the rear metal rubber ring 6 are made of metal wires through weaving and molding, which not only have high strength characteristics similar to the selected metal material, but also can produce a high damping effect through the internal friction of the metal wire, and the elastic modulus and material loss factor of the metal rubber can be adjusted by changing the length and width of the metal wire and the processing conditions, and finally achieve the mechanical characteristics of low stiffness and high damping. When the rotor journal 20 undergoes angular deformation, the outer ring 121 of the bearing will radially squeeze the metal rubber ring at the end, producing a certain damping effect, which helps to improve the vibration reduction performance of the damper.

[0039] The above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation of the present invention can still be modified or some technical features can be replaced by equivalents; without departing from the spirit of the technical solution of the present invention, all should be included in the scope of the technical solution claimed for protection by the present invention.

Claims

1. A half-spherical oil film ring structure suitable for the design of aero-engine pivot damping, characterized in that: The outer ring (2) comprises an inner ring (1), an outer ring (2), a front expansion ring (3), a rear expansion ring (4), a front metal rubber ring (5) and a rear metal rubber ring (6); the outer ring (2) is provided with radial oil holes, the front end of the outer ring (2) is provided with a front mounting hole (22), into which the front expansion ring (3) and the front metal rubber ring (5) are installed; the rear end of the outer ring (2) is provided with a rear mounting hole (23), into which the rear expansion ring (4) and the rear metal rubber ring (6) are installed; The inner ring (1) is located inside the outer ring (2); the outer ring surface (11) of the inner ring (1) and the inner ring surface (21) of the outer ring (2) are both ellipsoidal surfaces, forming a spherical radial gap (7) therebetween; the front expansion ring (3) and the rear expansion ring (4) seal the end faces of the spherical radial gap (7).

2. The half-spherical oil film ring structure suitable for the design of aero-engine fulcrum damping according to claim 1 is characterized in that: The outer ring (2) is a split-half structure, consisting of an upper ring (26) and a lower ring (27), and has an upper radial oil hole (28) and a lower radial oil hole (29) respectively opened in the middle.

3. The half-spherical oil film ring structure suitable for the design of aero-engine fulcrum damping according to claim 1 is characterized in that: The curvature radius of the outer ring surface (11) of the inner ring (1) in the cross section is set to R1, and the curvature radius of the inner ring surface (21) of the outer ring (2) in the cross section is R2, then the clearance value of the spherical radial clearance (7) is expressed as Δ = (R2 - R1).

4. The half-spherical oil film ring structure suitable for the design of aero-engine fulcrum damping according to claim 3 is characterized in that: The radius of curvature of the spherical radial clearance (7) in the cross section can be expressed as R3 = (R2 + R1) / 2.

5. The half-spherical oil film ring structure suitable for the design of aero-engine fulcrum damping according to claim 4 is characterized in that: In the radial direction, the radius of the spherical radial clearance (7) is r, and the relationship between the two satisfies R3 ≈(1.0~1.5)·r.

6. A half-spherical oil film ring structure suitable for aero-engine pivot damping design according to claim 1 or 2, characterized in that: The front metal rubber ring (5) and the rear metal rubber (6) are made of metal wires through weaving and molding.

7. The half-spherical oil film ring structure suitable for the design of aero-engine fulcrum damping according to claim 6, characterized in that: When the rotor journal (20) is angularly deformed, the bearing outer ring (121) radially squeezes the metal rubber ring at the end.

8. An aircraft engine rotor system using the half-spherical oil film ring structure suitable for aircraft engine pivot damping design as claimed in any one of claims 1 to 7, characterized in that: The half-spherical oil film ring structure is installed between the bearing outer ring (121) of the pivot bearing (12) and the rigid bearing seat (13). The upper radial oil hole (28) on the outer ring (2) is aligned with the radial oil hole (132) on the rigid bearing seat (13). The lubricating oil enters the spherical radial gap (7) through the axial oil hole (131) and the radial oil hole (132) of the rigid bearing seat (13) and the upper radial oil hole (28) on the outer ring (2) in sequence, forming a spherical oil film. The front expansion ring (3) and the rear expansion ring (4) seal the end face of the spherical radial gap (7) to prevent the lubricating oil from leaking out.

9. The aircraft engine rotor system according to claim 8, characterized in that: The baffle (16) is mounted on the rigid bearing seat (13) through a bolt connector (17) and axially compresses the front metal rubber ring (5) to prevent the oil film ring structure (10) from moving.

10. The aircraft engine rotor system according to claim 8, characterized in that: When the engine is operating, lubricating oil enters the spherical radial clearance (7) to form a spherical oil film, generating oil film damping, and when the rotor journal (20) undergoes angular deformation, driving the pivot bearing (12) and the inner ring (1) to tilt, the spherical radial clearance (7) maintains a stable clearance value and oil film thickness.

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