CN115030821A

CN115030821A - Aeroengine bearing cavity labyrinth sealing structure

Info

Publication number: CN115030821A
Application number: CN202110233800.8A
Authority: CN
Inventors: 杨璐瑜; 丁飞; 吴明峰
Original assignee: AECC Commercial Aircraft Engine Co Ltd
Current assignee: AECC Commercial Aircraft Engine Co Ltd
Priority date: 2021-03-03
Filing date: 2021-03-03
Publication date: 2022-09-09

Abstract

The labyrinth sealing structure is arranged between a main shaft and a casing and comprises a bearing inner ring, a bearing outer ring, an oil collecting ring and labyrinth sealing structures, the labyrinth sealing structures are axially arranged on two sides of the bearing cavity, each labyrinth sealing structure is provided with a sealing stator and a sealing rotor which rotate around the same axis and relatively, the sealing stator is sleeved on the outer side of the sealing rotor, a sealing protective layer is arranged on the inner side of the sealing stator, a plurality of sealing labyrinth teeth are arranged on the outer side of the sealing rotor, at least one groove is formed in the surface of the sealing protective layer, and the depth of the groove is smaller than the thickness of the surface of the sealing protective layer.

Description

Aero-engine bearing cavity labyrinth sealing structure

Technical Field

The invention belongs to the field of aero-engines, and particularly relates to a labyrinth sealing structure for a bearing cavity and an aero-engine.

Background

In a rotary machine such as an aircraft engine, gas leakage between a bearing cavity main shaft rotary member and a stationary bush and between a bearing cavity casing leads to a reduction in the overall thrust efficiency of the engine and an increase in the amount of oil consumed. For an aircraft engine, the sealing capability of the region is improved, the pressure difference between the front and the back of the sealing section is increased, high-temperature peripheral gas entering a bearing cavity from the sealing section is reduced, the thermal load of the bearing cavity and the consumption of lubricating oil can be reduced, and the performance parameters of the engine, such as the oil consumption rate, the propulsion efficiency and the like, are directly influenced by the sealing capability, so that the good sealing effect is very necessary to be ensured as far as possible.

The labyrinth seal structure is widely applied to various parts of an aircraft engine as the most common seal structure form of the aircraft engine, and the labyrinth seal structure reduces pressure by means of airflow from a high-pressure area through narrow gaps formed by a plurality of grates and a planar honeycomb structure and a cavity between the two grates, so that leakage is reduced. When the airflow flows through the first grate gap, the flow speed is increased, and the pressure is reduced; when the gas flows to the cavity between the two grid teeth, the gas expands, turbulence is generated, the energy of the gas flow is lost, and the pressure and the speed of the gas flow are reduced. Therefore, after passing through a plurality of grate teeth, the pressure difference between the front and the back of the grate teeth is reduced, the air flow passing through the gaps of the grate teeth is also reduced, and the whole leakage amount is reduced.

However, the labyrinth sealing structure in the prior art has an unsatisfactory effect in the practical application of the bearing cavity. Especially when the aircraft engine is in a low state, the following problems are generally caused:

1. because the pressure in the bearing cavity is higher than the pressure in the surrounding cavity, the gas or lubricating oil in the bearing cavity leaks, the gas temperature between the bearing cavity and other external cavities is influenced, the air-entraining load is increased, and the performance of the aircraft engine is influenced.

2. The operation of the aircraft engine needs to ensure the lubrication of the bearing, a lubricating oil flow path for keeping circulation is arranged in the bearing cavity, the oil temperature can rise after the lubricating oil operates in the bearing cavity for a period of time, the lubricating oil needs to be guided to an external casing through the circulation flow path for cooling so as to ensure that the lubricating oil continuously operates at a more proper temperature, and the lubricating oil in the bearing cavity is likely to leak due to the fact that the pressure in the bearing cavity is higher than the pressure of a surrounding cavity, so that the working efficiency of the bearing is affected, and the leaked lubricating oil can further cause the potential safety hazard of the aircraft engine;

3. in the working process, a gap exists between the rotor and the stator of the bearing cavity, the gas exciting force can enable the part of the bearing cavity to generate forced vibration, and when the frequency of the exciting force is the same as the natural frequency of the part, resonance can occur, and serious results are caused.

4. Because the installation space of the bearing cavity of the aeroengine is narrow, in the axial dismounting process, the rotor and the stator of the sealing structure are easy to rub, and the excessively complex sealing structure is difficult to process and brings extra difficulty and workload for dismounting the bearing cavity.

Disclosure of Invention

The invention aims to provide a labyrinth sealing structure of an aeroengine bearing cavity, which solves the technical problems in the prior art, optimizes the sealing effect of the bearing cavity, reduces the leakage amount and improves the performance of an engine.

The technical scheme of the labyrinth sealing structure of the bearing cavity of the aero-engine provided by the invention is as follows: the labyrinth sealing structure is arranged between a main shaft and a casing and is formed by a bearing inner ring, a bearing outer ring, an oil collecting ring and the labyrinth sealing structure, the labyrinth sealing structure is axially arranged on two sides of the bearing cavity, the labyrinth sealing structure is provided with a sealing stator and a sealing rotor which rotate around the same axis and relatively, the sealing stator is sleeved on the outer side of the sealing rotor, a sealing protective layer is arranged on the inner side of the sealing stator, a plurality of sealing labyrinth teeth are arranged on the outer side of the sealing rotor, at least one groove is formed in the surface of the sealing protective layer, and the depth of the groove is smaller than the thickness of the surface of the sealing protective layer.

Preferably, the grooves are formed in opposite surfaces of a gap formed between every two adjacent sealing labyrinth teeth, and the width of each groove is smaller than the gap formed between every two adjacent sealing labyrinth teeth.

Preferably, the grooves comprise a first groove and a second groove, and the first groove and the second groove are respectively axially arranged at two ends of the labyrinth sealing structure.

Preferably, the grooves are distributed intermittently along the circumferential direction of the surface of the sealing protection layer.

Preferably, the grooves are distributed along 90-degree intervals, and the circumferential angle of each section of the groove is 50-70 degrees.

Preferably, the cross-sectional shape of the groove in the axial direction of the bearing cavity is semicircular.

Preferably, the cross-sectional shape of the groove in the axial direction of the bearing cavity is rectangular.

Preferably, the sealing protective layer is a honeycomb structure or an easily-worn coating.

Preferably, the cross-sectional area of the sealing labyrinth is gradually reduced from the root part to the top part of the labyrinth, and the width of the top part of the sealing labyrinth is close to 0.

In addition, the invention also provides an aero-engine which comprises a compressor, a combustion chamber and a turbine, wherein the compressor and/or the turbine comprise a plurality of bearing cavities, and the bearing cavities comprise any one of the labyrinth sealing structures.

By applying the labyrinth sealing structure of the bearing cavity and the aero-engine provided by the invention, the problems in the prior art can be solved from the source, and the following advantages are brought:

firstly, the labyrinth sealing structure of the bearing cavity of the aero-engine provided by the invention can damage the boundary layer, generate vortex and reduce gas leakage. After the airflow flows through the narrow gaps of the labyrinth, the boundary layer of the airflow on the surface of the honeycomb can be damaged by the groove structure, so that eddy current is generated, energy dissipation is caused, and the blocking effect of each single-stage labyrinth in the labyrinth sealing structure on the airflow is enhanced, thereby reducing the leakage of the air, ensuring the sealing effect between the cavities on two sides, and improving the efficiency and the performance of the engine;

secondly, the labyrinth seal structure of the bearing cavity of the aero-engine provided by the invention can contain lubricating oil in the bearing cavity and reduce the leakage of the lubricating oil in a low state. When the engine works in a low state, the pressure in the bearing cavity is higher than that outside the cavity, so that the risk of leakage of lubricating oil outside through the labyrinth seal exists, the pressure reduction effect of the single-stage labyrinth can be increased by the groove structure, the sealing effect is improved, and the risk of leakage of the lubricating oil is reduced;

thirdly, according to the labyrinth seal structure of the bearing cavity of the aero-engine, which is provided by the invention, the labyrinth seal is used as a special connection mode between the rotor part and the stator part, in the working process, gas exciting force exists, the capacity of a cavity between the labyrinth can be increased by increasing the groove structure, the gas impact force suffered by the seal position is reduced, and the vibration of the aero-engine in the operation process is reduced;

fourthly, the labyrinth sealing structure of the bearing cavity of the aero-engine provided by the invention can effectively reduce axial friction in the installation process, and is convenient to install. Because the space of the bearing cavity is narrow, the reliability and feasibility of the assembling and decomposing processes can be ensured while the sealing efficiency is improved;

fifth, the labyrinth seal structure of the bearing cavity of the aero-engine provided by the invention is simple in structure, can be suitable for various seal surfaces such as a honeycomb structure and an easily-abraded coating, is convenient to process, and has better processability compared with other seal forms of structures.

These and other objects and advantages will become more apparent to those skilled in the art after reading the following portions of this specification in conjunction with the accompanying drawings.

Drawings

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. It is to be noted that the appended drawings are intended as examples of the claimed invention. In the drawings, like reference characters designate the same or similar elements.

FIG. 1 is a schematic view of an aircraft engine bearing cavity configuration of the present invention.

Fig. 2 is a partially enlarged schematic view of a bearing cavity labyrinth sealing structure according to a first preferred embodiment of the present invention.

FIG. 3 is a schematic view of a conventional bearing cavity labyrinth sealing structure in the prior art.

Fig. 4 is a schematic circumferential structure view of a labyrinth sealing structure of a bearing cavity according to a second preferred embodiment of the invention.

Fig. 5 is a schematic diagram of a groove structure of a labyrinth seal structure of a bearing cavity according to a third preferred embodiment of the invention.

Fig. 6 is a schematic diagram of a groove structure of a labyrinth seal structure of a bearing cavity according to a fourth preferred embodiment of the invention.

The reference numbers are as follows:

100. labyrinth sealing structure

110. Sealing stator

111. Sealing protective layer

112. Groove

1121. A first groove

1122. Second groove

120. Sealing rotor

121. Grid section

200. Bearing inner ring

300. Bearing stator outer ring seat

400. Bearing assembly

500. Oil collecting ring

600. Main shaft

L1, groove width

L2, and the interval width formed by two adjacent sealing labyrinth teeth

S1, depth of groove

S2, sealing and protecting layer thickness

Alpha, groove circumferential angle

Detailed Description

The detailed features and advantages of the present invention are described in detail in the detailed description which follows, and will be sufficient for anyone skilled in the art to understand the technical content of the present invention and to implement the present invention, and the related objects and advantages of the present invention will be easily understood by those skilled in the art from the description, claims and drawings disclosed in the present specification.

Fig. 1 to fig. 2 show technical solutions of a labyrinth sealing structure of an aeroengine bearing cavity provided by the present invention, the bearing cavity is arranged between an aeroengine main shaft 600 and a casing (not shown in the figure), and is formed by a bearing inner ring 200, a bearing 400, a bearing stator outer ring seat 300, an oil collecting ring 500 and the labyrinth sealing structure 100, and the labyrinth sealing structure 100 is axially arranged on two sides of the bearing cavity.

The labyrinth sealing structure 100 comprises a sealing stator 110 and a sealing rotor 120 which rotate around the same axis and relatively, the sealing stator 110 is sleeved on the radial outer side of the sealing rotor 120, a sealing protective layer 111 is arranged on the inner side of the sealing stator 110, and the sealing protective layer can be a honeycomb structure or an easily-worn coating so as to prolong the service life of the labyrinth sealing structure. The outer side of the sealing rotor 120 is provided with a plurality of sealing labyrinth teeth 121, the cross-sectional area of the sealing labyrinth teeth is gradually reduced from the root part to the top part of the labyrinth teeth, and the width of the top part of the sealing labyrinth teeth is close to 0. The sealing labyrinth structure of the invention is not limited to the above forms, and various conventional labyrinth forms including straight teeth can be adopted in other embodiments.

The surface of the sealing protection layer 111 is provided with two annular grooves 112, that is, a first groove 1121 and a second groove 1122, which are both arranged on opposite surfaces of a space formed by two adjacent sealing labyrinth teeth and are respectively arranged at two ends of the labyrinth tooth sealing structure along the axial direction. The cross sections of the first groove 1121 and the second groove 1122 are semicircular, the widths (diameters) L1 of the first groove 1121 and the second groove 1122 are equal and are both smaller than the width L2 of the interval formed by two adjacent sealing labyrinth teeth, and the depth (radius) S1 of the groove 112 is smaller than the thickness S2 of the sealing protection layer 111.

During operation, airflow flows towards the inside of the bearing cavity along the axial direction of the main shaft 6 of the aircraft engine under the action of huge pressure difference between the outer side and the inner side of the bearing cavity, and in a low working state, the pressure in the bearing cavity is higher than that outside the bearing cavity, so that the airflow needs to be prevented from flowing towards the outside of the bearing cavity along the axial direction of the main shaft 6 of the aircraft engine. By applying the sealing labyrinth structure, no matter in any working state, airflow enters the first groove 1121 or the second groove 1122 on the surface of the sealing protection layer on the inner side of the sealing stator 110 immediately after flowing through a narrow gap between the first-stage labyrinth on the two sides of the bearing cavity and the sealing protection layer, the boundary layer of the airflow on the surface of the sealing protection layer of the sealing structure can be damaged through the groove structure, vortex is generated on the surface of the sealing protection layer 111, the energy dissipation degree of the airflow is enhanced, the blocking effect of the single-stage labyrinth on the airflow is enhanced, and accordingly, the leakage of the gas is reduced. The groove structure further increases the volume of the space between the two stages of the labyrinth teeth, and increases the pressure reduction effect of each stage of the labyrinth teeth, thereby ensuring the sealing effect between the inside and the outside of the bearing cavity and improving the efficiency and the performance of the engine.

Secondly, through set up groove structure in the protective layer 111 that obturages, can allow inside at aeroengine low state of obturage protective layer, hold a part of lubricating oil, because the lubricating oil in the bearing chamber outwards leaks and probably causes aeroengine's potential safety hazard.

And thirdly, the groove structure in the sealing protective layer 111 can increase the capacity of a cavity formed between the labyrinth teeth, reduce the gas impact force suffered by the sealing position and facilitate reducing vibration. Meanwhile, the groove structure is arranged on the sealing stator 110, the sealing rotor is not changed, the phenomenon of non-uniform circumferential direction on the sealing rotor is avoided, more serious exciting force and rotor imbalance are caused, and the balance state of the rotor can be ensured

When the bearing cavity is disassembled and assembled, the sealing stator 110 is sleeved outside the sealing rotor 120, a complex matching structure does not exist between the sealing stator and the sealing rotor, the sealing stator and the sealing rotor can be directly disassembled and assembled along the axial direction, the axial collision and friction of the sealing stator and the sealing rotor in the disassembling and assembling process can be effectively avoided, no additional tool is needed, and the disassembling and assembling workload is greatly reduced.

Fig. 4 shows a second preferred embodiment of the labyrinth sealing structure of the bearing cavity of the aeroengine, which shows the circumferential distribution of the annular grooves of the labyrinth sealing structure, and the axial structure of the labyrinth sealing structure can be seen in fig. 2.

The labyrinth sealing structure 100 is provided with a sealing stator 110 and a sealing rotor 120 which rotate relatively around the same axis, the sealing stator 110 is sleeved on the radial outer side of the sealing rotor 120, a sealing protective layer 111 is arranged on the inner side of the sealing stator 110, and the sealing protective layer can be a honeycomb structure or an easily-ground coating so as to prolong the service life of the labyrinth sealing structure. The outer side of the sealing rotor 120 is provided with a plurality of sealing labyrinth teeth 121, the cross-sectional area of the sealing labyrinth teeth is gradually reduced from the root part to the top part of the labyrinth teeth, and the width of the top part of the sealing labyrinth teeth is close to 0.

Two circles of annular grooves 112 are formed in the surface of the sealing protection layer 111, namely, a first groove 1121 and a second groove 1122 are formed in opposite surfaces of a gap formed by two adjacent sealing labyrinth teeth and are respectively axially arranged at two ends of the labyrinth sealing structure. The widths L1 of the first groove 1121 and the second groove 1122 are equal and are both smaller than the width L2 of the interval formed by two adjacent sealing labyrinth teeth, and the depth S1 of the groove 112 is smaller than the thickness S2 of the sealing protection layer 111.

The first grooves 1121 and the second grooves 1122 are distributed in four segments along the circumferential surface of the sealing protection layer 111 at intervals of 90 degrees, and the circumferential angle α of each segment of the grooves is 60 degrees.

Because the labyrinth 121 rotates along with the main shaft 6, circumferential flow in the rotating direction exists between the top of the labyrinth and the sealing protective layer 111, the groove structures are arranged to be circumferentially discontinuously, when airflow circumferentially passes through a gap between the top of the labyrinth and the sealing protective layer 111, the groove structures disturb regular circumferential movement of the airflow, the airflow expands at each section of groove, turbulence is generated to cause energy loss of the airflow, the pressure and the speed of the airflow are reduced, part of energy is dissipated into heat energy, and at the discontinuous position between the grooves, the airflow speed is further increased, the pressure is reduced, the leakage amount of the labyrinth structure is further reduced, and the sealing effect is improved.

In other embodiments, the circumferential angle α and the circumferential distribution number of the grooves of each section can be selected by referring to the installation position, the working condition, the installation space and other factors of the labyrinth sealing structure, and the preferred axial angle is between 50 and 70 degrees.

Fig. 5 and 6 show other preferred embodiments of the labyrinth seal structure of the bearing cavity of the aeroengine provided by the invention.

As shown in fig. 5, in the third embodiment of the labyrinth sealing structure for the bearing cavity of the aircraft engine provided by the invention, a plurality of annular grooves are formed in the surface of the sealing protection layer, the number of the annular grooves is 1 less than the number of the sealing labyrinth, the annular grooves are all arranged on opposite surfaces of a gap formed by two adjacent sealing labyrinth, the cross sections of the annular grooves are semicircular, the widths (diameters) L1 of the annular grooves are equal to each other and are smaller than the width of the gap formed by two adjacent sealing labyrinth, and the depth (radius) S1 of each groove is smaller than the thickness of the sealing protection layer 111.

Through setting up a plurality of groove structure, further reduce the air current leakage of structure of obturating, improved the holistic effect of obturating of labyrinth structure.

As shown in fig. 6, according to a fourth embodiment of the labyrinth sealing structure of the bearing cavity of the aeroengine provided by the invention,

the sealing protective layer is provided with a plurality of annular grooves, the number of the annular grooves is 1 less than that of the sealing labyrinth teeth, the annular grooves are arranged on opposite surfaces of an interval formed by two adjacent sealing labyrinth teeth, the cross sections of the annular grooves are rectangular, the axial widths L1 of the annular grooves are equal and are smaller than the width of the interval formed by two adjacent sealing labyrinth teeth, and the depth S1 of each groove is smaller than the thickness of the sealing protective layer 111.

By adjusting the sectional shape of the groove structure, in other embodiments, the geometric parameters of the groove can be selected by referring to the installation position, working conditions, installation space and other factors of the labyrinth sealing structure.

The invention also provides an aircraft engine which comprises the gas compressor, the combustion chamber and the turbine, wherein the bearing cavities of the gas compressor and the turbine comprise the labyrinth sealing structures, so that the stronger sealing effect and the higher safety are obtained, and the workload required by the disassembly and the assembly of the bearing seat is saved.

According to the embodiment, by applying the bearing cavity labyrinth sealing structure and the aircraft engine provided by the invention, the boundary layer of airflow flowing through the sealing labyrinth can be damaged, vortex is generated, gas leakage is reduced, the sealing effect between the cavities on two sides is ensured, and the efficiency and the performance of the engine are improved; lubricating oil in the bearing cavity can be contained, so that the lubricating oil leakage in a low state is reduced, and the sealing effect is improved; the groove structure can be increased, the capacity of a cavity between the grid teeth can be increased, the gas impact force suffered by the sealing position is reduced, and the vibration is reduced; the sealing structure has the advantages of simple structure, convenience in processing and good processability compared with other existing sealing structure technical schemes; can effectively reduce the axial friction in the installation process and is convenient to install. Because the space of the bearing cavity is narrow, the reliability and the feasibility of the assembling and disassembling processes can be ensured while the sealing efficiency is ensured to be improved.

The terms and expressions which have been employed herein are used as terms of description and not of limitation. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.

Also, it should be noted that although the present invention has been described with reference to the current specific embodiments, it should be understood by those skilled in the art that the above embodiments are merely illustrative of the present invention, and various equivalent changes or substitutions may be made without departing from the spirit of the present invention, and therefore, it is intended that all changes and modifications to the above embodiments be included within the scope of the claims of the present application.

Claims

1. A labyrinth sealing structure for a bearing cavity of an aircraft engine is disclosed, wherein the bearing cavity is arranged between a main shaft and a casing of the aircraft engine, the labyrinth sealing structure is axially arranged on two sides of the bearing cavity to seal the bearing cavity,

the method is characterized in that: the labyrinth sealing structure is provided with a sealing stator and a sealing rotor which rotate relatively around the same axis, the sealing stator is sleeved on the radial outer side of the sealing rotor, a sealing protective layer is arranged on the inner side of the sealing stator, a plurality of sealing labyrinth teeth are arranged on the outer side of the sealing rotor, a groove is formed in at least one position, corresponding to the interval formed by every two adjacent sealing labyrinth teeth, of the surface of the sealing protective layer, and the depth of the groove is smaller than the thickness of the sealing protective layer.

2. The labyrinth seal structure for an aircraft engine bearing cavity as defined in claim 1, wherein the width of the groove is smaller than the interval formed by two adjacent seal labyrinth.

3. The labyrinth seal structure for an aircraft engine bearing cavity as claimed in claim 2, wherein the grooves comprise a first groove and a second groove, and the first groove and the second groove are respectively axially disposed at two ends of the labyrinth seal structure.

4. The labyrinth seal for an aircraft engine bearing cavity as defined in claim 1, wherein the grooves are circumferentially intermittently and/or continuously distributed along the surface of the seal protection layer.

5. The labyrinth seal structure for an aircraft engine bearing cavity as claimed in claim 4, wherein the grooves are intermittently distributed along 90 degrees into four segments, and the circumferential angle of each segment of the groove is between 50 degrees and 70 degrees.

6. The labyrinth sealing structure for an aircraft engine bearing cavity according to claim 1, wherein the groove has a semicircular shape in cross section along the axial direction of the bearing cavity.

7. The labyrinth seal for an aircraft engine bearing cavity as defined in claim 1, wherein the groove has a rectangular cross-sectional shape along the axial direction of the bearing cavity.

8. The labyrinth seal for an aircraft engine bearing cavity as defined in claim 1, wherein the seal protection layer is a honeycomb structure or an abradable coating.

9. The labyrinth sealing structure for an aircraft engine bearing cavity as claimed in claim 1, wherein the cross-sectional area of the sealing labyrinth gradually decreases from the root to the top of the labyrinth, and the top width of the sealing labyrinth is approximately 0.

10. An aircraft engine, the aircraft engine comprises a compressor, a combustion chamber and a turbine, the compressor and/or the turbine comprises a plurality of bearing cavities, and the aircraft engine is characterized in that at least one bearing cavity is provided with a labyrinth sealing structure according to any one of claims 1-9.