Sealing structure and aero-engine
By adjusting the flow hole area using shape memory alloy bushings, the thermal management and sealing pressure difference issues of the aero-engine bearing cavity under different operating conditions were solved, thus achieving stable operation and safety of the bearing cavity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AECC COMML AIRCRAFT ENGINE CO LTD
- Filing Date
- 2024-10-17
- Publication Date
- 2026-04-17
AI Technical Summary
Existing aero-engine bearing cavities are difficult to effectively manage thermally and regulate sealing pressure differentials under different operating conditions, leading to problems such as excessively high bearing cavity temperature or lubricating oil leakage.
The shape memory alloy bushing automatically adjusts the area of the flow hole according to the temperature change of the sealing cavity, so that the flow hole increases the flow area to reduce the temperature under large conditions, and decreases the flow area to increase the pressure difference under small conditions.
It achieves precise thermal management and sealing differential pressure adjustment of the bearing cavity under different operating conditions, avoiding overheating of the bearing cavity and oil leakage, and ensuring safe operation of the bearing.
Smart Images
Figure CN121875801A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft engines, and more particularly to a sealing structure and an aircraft engine. Background Technology
[0002] With the continuous improvement of aero-engine technology, turbine exhaust temperatures are also constantly increasing. The bearing cavity behind the turbine is actually in an extremely complex thermal environment. On the one hand, it bears the high-temperature heat transferred from the turbine end through heat conduction and the heating of the gas inside the sealed cavity; on the other hand, the hot gas entering from the grate seal structure before and after the bearing cavity also brings in a large amount of heat, further increasing the thermal load on the bearing cavity. Overheating of the bearing cavity or excessively high bearing temperature can lead to bearing failure, carbon buildup and coking of the lubricating oil on the inner walls of the bearing cavity and ventilation pipes, and even premature degradation of the lubricating oil's physical properties, bearing cavity ignition, and spontaneous combustion. This places higher demands on the thermal management capabilities of the bearing cavity.
[0003] Under high-pressure conditions, i.e., when the sealing gas temperature is high and the sealing pressure difference is large, the temperature of the sealing cavity is often higher than expected. To ensure sealing safety, it is necessary to reduce the temperature of the sealing cavity to lower the temperature of the bearing cavity. Under low-pressure conditions, i.e., when the sealing gas temperature is low and the sealing pressure difference is small, it is necessary to increase the sealing pressure difference to ensure the sealing effect of the bearing cavity and avoid problems such as lubricating oil leakage and increased lubricating oil consumption in the bearing cavity. Generally, the sealing pressure difference between the sealing cavity and the bearing cavity is required to be no less than 5 kPa.
[0004] Therefore, it is necessary to design a sealing structure that can reduce the sealing cavity temperature under high pressure and increase the sealing pressure difference under low pressure. Summary of the Invention
[0005] The purpose of this invention is at least to provide a sealing structure that reduces the sealing cavity temperature under high pressure conditions and increases the sealing pressure difference under low pressure conditions, so as to meet the thermal management requirements of the bearing cavity and the sealing pressure difference requirements of aero-engines at different speeds.
[0006] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.
[0007] One embodiment of the present invention provides a sealing structure, which includes a sealing cavity and a sealing seat for defining the sealing cavity. The sealing seat has a flow hole for the passage of sealing gas. A bushing is provided on the sealing seat, and a first side of the bushing is fixed relative to the sealing seat. At least a portion of the bushing is made of a shape memory alloy. The deformation of the shape memory alloy is controlled by the temperature of the sealing gas. The deformation of the shape memory alloy causes a change in the area of at least a portion of the bushing, so that the flow hole has at least two states, including a fully open state and a fully closed state.
[0008] In some embodiments, the rate of change of at least a portion of the bushing area is 0% to 100% in a temperature range of 60°C to 350°C.
[0009] In some embodiments, the bushing is fitted onto the outer side of the sealing seat relative to the sealing cavity.
[0010] In some embodiments, the bushing extends along the axial direction of the engine, and the first side of the bushing along the axial direction is fixed relative to the sealing seat. The area of at least a portion of the bushing varies along the axial direction. The flow area of the flow hole is inversely related to the area of at least a portion of the bushing. When the bushing area is at its maximum, the flow hole is in a completely closed state, and the flow area of the flow hole is 0.
[0011] In some embodiments, the flow hole is a shape that extends axially, and the shape of the flow hole includes square, square-round, elliptical, and wavy.
[0012] In some embodiments, the flow hole includes a plurality of flow holes, which are uniformly arranged along the axial direction.
[0013] In some embodiments, the flow holes include multiple rows of flow holes arranged axially, and the bushings include multiple bushings, which are disposed corresponding to the multiple rows of flow holes.
[0014] In some embodiments, a mounting flange is provided on the first side of the bushing, the mounting flange extending in a direction perpendicular to the axial direction, and the mounting flange is fixedly mounted to the sealing seat.
[0015] One embodiment of the present invention also provides an aero-engine, including a bearing cavity, and further including the above-mentioned sealing structure for sealing the bearing cavity, an air bleed pipeline, a compressor, and a low-pressure turbine; the air bleed pipeline is connected between the compressor and the sealing cavity, and the air bleed pipeline guides the gas in the compressor to the sealing cavity; the sealing seat defining the sealing cavity is disposed close to the low-pressure turbine, and the sealing gas in the sealing cavity can flow to the low-pressure turbine through the flow hole provided on the sealing seat.
[0016] The sealing structure and aero-engine involved in this invention can automatically shorten to open the flow orifice, increase the flow area, and reduce the temperature of the sealing gas under the actual operating conditions of the aero-engine, in response to the temperature of the sealing gas during high-pressure conditions (i.e., high sealing gas temperature and large sealing pressure difference). Conversely, under low-pressure conditions (i.e., low sealing gas temperature and small sealing pressure difference), the bushing automatically extends to cover the flow orifice, reducing the flow area and increasing the sealing pressure difference. By designing a bushing that automatically adjusts the flow area in response to the sealing gas temperature, the thermal management requirements of the bearing cavity and the sealing pressure difference requirements at different engine speeds can be met. This enables precise gas supply to the sealing cavity outside the engine bearing cavity, thus promoting further development of aero-engine technology. Attached Figure Description
[0017] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related properties or features may have the same or similar reference numerals. Wherein:
[0018] Figure 1 This is a partial structural schematic diagram of an aero engine based on some embodiments;
[0019] Figure 2 This is a structural schematic diagram of the sealing structure shown in some embodiments;
[0020] Figure 3 This is a structural flowchart of the sealing structure according to some other embodiments;
[0021] Figure 4 This is a structural flowchart of the bushing according to some embodiments. Detailed Implementation
[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.
[0023] It is understood that the technical terms that may be used in the description of this specification, such as “center,” “longitudinal,” “lateral,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the implementation method and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the invention.
[0024] It should be noted that the use of terms such as "first" and "second" to define features in this article is merely for the purpose of distinguishing the corresponding features. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.
[0025] Figure 1 This is a partial structural schematic diagram of an aero engine according to some embodiments.
[0026] like Figure 1 As shown, the aero-engine 100 includes a bearing cavity 1, a compressor, a sealing structure 2, an air bleed line 3, and a low-pressure turbine 4.
[0027] A bearing cavity 1 is formed between the rotor and stator of the aero-engine 100. A pressurized gas is used to seal the bearing cavity 1 to ensure that the lubricating oil used for lubrication and cooling of the bearings (e.g., bearing 5) does not leak. The sealing structure 2 includes a sealing cavity 21 and a sealing seat 22. The sealing cavity 21 is located around the bearing cavity 1, and the bearing cavity 1 is connected to the sealing cavity 21 through a grate sealing structure 6, which surrounds the grate sealing structure 6. During the operation of the aero-engine 100, the lubricating oil in the bearing cavity 1 usually exists in the form of oil vapor. The sealing cavity 21 introduces pressurized sealing gas from the outside to seal the lubricating oil vapor attempting to leak from the grate sealing structure 6, thereby establishing pressure within the bearing cavity 1. The pressure inside the sealing cavity 21 is greater than the pressure inside the bearing cavity 1. Due to the pressure difference between the inside and outside of the bearing cavity 1, the sealing gas in the sealing cavity 21 can effectively seal the lubricating oil vapor within the bearing cavity 1.
[0028] In some embodiments, sealing gas is introduced from a compressor (not shown) and a gas duct 3 is established between the compressor and the sealing chamber 21 to guide the gas from the compressor to the sealing chamber 21, forming sealing gas. Figure 1 The arrows shown roughly indicate the flow direction of the sealing gas. The operating conditions and speed of the aero-engine 100 are variable, causing fluctuations in the temperature and sealing pressure difference (the difference in internal pressure between the sealing cavity 21 and the bearing cavity 1) within the sealing cavity 21. These fluctuations occur under both high-pressure and low-pressure conditions. Under high-pressure conditions, i.e., when the sealing gas temperature is high and the sealing pressure difference is large, the cavity temperature of the sealing cavity 21 often exceeds the expected value. To ensure sealing safety, the flow rate of the sealing gas flowing out of the sealing cavity 21 can be increased to lower the temperature of the sealing cavity 21, thereby lowering the temperature of the bearing cavity 1. However, under low-pressure conditions, i.e., when the sealing gas temperature is low and the sealing pressure difference is small, to ensure the sealing effect of the bearing cavity, the flow rate of the sealing gas flowing out of the sealing cavity 21 can be reduced, increasing the sealing pressure difference within the sealing cavity 21. This avoids problems such as lubricating oil leakage and increased lubricating oil consumption in the bearing cavity.
[0029] This specification provides a sealing structure including a sealing seat 22 for defining a sealing cavity 21. The sealing seat 22 is the portion surrounding the sealing structural member forming the sealing cavity 21. A flow hole 221 is provided on the sealing seat 22 defining the sealing cavity 21. The sealing seat 22 is located close to the low-pressure turbine 4, and the sealing gas in the sealing cavity 21 can flow strongly towards the disk of the low-pressure turbine 4 through the flow hole 221 provided on the sealing seat 22. The flow area of the flow hole 221 is adjustable, and the size of the flow area of the flow hole 221 can affect the sealing pressure difference and the sealing gas temperature in the sealing cavity 21. The flow area of the flow hole 221 refers to the cross-sectional area through which the sealing gas can pass. When the flow area of the flow hole 221 is at its maximum, the flow area of the flow hole 221 is equal to its opening area. Under high operating conditions, the flow area of the flow hole 221 can be increased to increase the flow rate of the sealing gas flowing out of the sealing cavity 21 and reduce the temperature of the sealing cavity 21. Under low operating conditions, the flow area of the flow hole 221 can be decreased to decrease the flow rate of the sealing gas flowing out of the sealing cavity 21 and increase the sealing pressure difference of the sealing cavity 21.
[0030] In some embodiments, a bushing 222 is provided on the sealing seat 22, correspondingly covering the flow hole 221. At least a portion of the bushing 222 is made of a shape memory alloy, including Ti (titanium), Ni (nickel), Pd (platinum), etc. The shape memory alloy deforms with temperature changes. The bushing 222 covers the sealing seat 22, and the temperature of the sealing cavity 21 can be transferred to the bushing 222 through the sealing seat 22. The shape memory alloy can deform with temperature changes, and the deformation of the shape memory alloy is controlled by the temperature of the sealing cavity 21. The temperature of the sealing cavity 21 is affected by the temperature of the sealing gas; therefore, the deformation of the shape memory alloy is controlled by the temperature of the sealing gas. The deformation of the shape memory alloy causes at least a portion of the area of the bushing 222 to change, so that the flow hole 221 has at least two states, including a fully open state and a fully closed state. When the flow hole 221 is in the fully open state, its flow area is the largest; when the flow hole 221 is in the fully closed state, its flow area is the smallest, which is 0.
[0031] In some embodiments, the area change of at least a portion of the bushing 222, which is made of shape memory alloy, is inversely correlated with the temperature of the sealing cavity 21. When the temperature of the sealing cavity 21 is high, the area of at least a portion of the bushing 222 decreases to open the flow hole 221, increasing the flow area of the flow hole 221. When the temperature of the sealing cavity 21 is low, the area of at least a portion of the bushing 222 increases to cover the flow hole 221, reducing the flow area of the flow hole 221. In some embodiments, the deformation temperature of the shape memory alloy is set according to the target temperature range of the sealing cavity 21. When the actual temperature of the sealing cavity 21 is within the target temperature range, the shape memory alloy does not deform, the temperature of the bearing cavity 1 is suitable, and the sealing pressure difference is also within the target pressure difference range, thus ensuring the sealing of the bearing cavity 1. When the actual temperature of the sealing cavity 21 exceeds or falls below the target temperature range, the shape memory alloy deforms accordingly to adjust the flow area of the flow hole 221. When the temperature of the sealing cavity 21 is adjusted to the target temperature range, the sealing pressure difference is also within the target pressure difference range, ensuring the sealing of the bearing cavity 1 and the safe operation of the bearing.
[0032] In some embodiments, the target temperature range for the sealing cavity 21 is less than 70°C. In some embodiments, the area change rate of at least a portion of the bushing 222 is 0% to 100% in the temperature range of 60°C to 350°C. Specifically, when the temperature of the sealing cavity 21 is 60°C, the area change rate of at least a portion of the bushing 222 is 0%, meaning that the bushing 222 hardly deforms at 60°C and has the largest area. When the temperature of the sealing cavity 21 is 350°C, the area change rate of at least a portion of the bushing 222 is 100%, meaning that the bushing 222 undergoes the largest deformation at 350°C and has the smallest area. Here, the area of the bushing 222 refers to the side surface area of the bushing 222 parallel to the axial direction. In some embodiments, the area change rate of at least a portion of the bushing 222 is 0% to 100% in a temperature range of 70°C to 340°C, wherein the area change rate of at least a portion of the bushing 222 is 0% when the temperature of the sealing cavity 21 is 70°C, and the area change rate of at least a portion of the bushing 222 is 100% when the temperature of the sealing cavity 21 is 340°C. In some embodiments, the area change rate of at least a portion of the bushing 222 is 0% to 100% in a temperature range of 80°C to 330°C, wherein the area change rate of at least a portion of the bushing 222 is 0% when the temperature of the sealing cavity 21 is 80°C, and the area change rate of at least a portion of the bushing 222 is 100% when the temperature of the sealing cavity 21 is 330°C.
[0033] In some embodiments, at least a portion of the bushing 222, made of shape memory alloy, is a region corresponding to the flow hole 221, enabling adjustment of the flow area of the flow hole 221 in response to the temperature of the sealing cavity 21. In some embodiments, a first side of the bushing 222 is fixed relative to the sealing seat 22, and at least a portion of the bushing 222 away from the first side is made of shape memory alloy.
[0034] In some embodiments, bushing 222 is along the axial direction of the engine (reference). Figure 4 (Extension). The axial direction of the engine, as referred to in this specification, means the direction in which the engine rotates from its center. Bushing 222 is fixed relative to sealing seat 22 on its first side along the axial direction. In some embodiments, such as... Figure 2 As shown, a mounting flange 223 is provided on the first side of the bushing 222. The mounting flange 223 extends in a direction perpendicular to the axial direction and is fixedly mounted to the sealing seat 22. In some embodiments, the mounting flange 223 and the sealing seat 22 are detachably connected, facilitating the removal of the bushing 222 and enabling maintenance and replacement of the bushing 222. For example, the mounting flange 223 and the sealing seat 22 are connected by bolts and nuts. In some embodiments, to facilitate maintenance and replacement of the bushing 222, the bushing 222 is fitted against the outer surface of the sealing seat 22 relative to the sealing cavity 21. In some embodiments, the shape and structure of the bushing 222 are adapted to the shape and structure of the outer surface of the sealing seat 22. In some embodiments, such as Figure 4 As shown, the outer surface of the sealing seat 22 is an arc-shaped structure, and the bushing 222 is an arc-shaped structure that adapts to the outer surface of the sealing seat 22. In some embodiments, such as Figure 4 As shown, the outer surface of the sealing seat 22 is an arc surface structure, and the inner surface of the bushing 222 near the sealing seat 22 is an arc surface structure that is compatible with the outer surface of the sealing seat 22.
[0035] In some embodiments, at least a portion of the area of the bushing 222 varies axially, and the flow area of the flow hole 221 is inversely related to the area of at least a portion of the bushing. For example... Figure 2 As shown, at least a portion of the bushing 222 elongates axially when the temperature of the sealing cavity 21 is low, covering the flow hole 221 opened on the sealing seat 22, thereby reducing the flow area and increasing the sealing pressure difference. Figure 3As shown, at least a portion of the bushing 222 shortens axially when the temperature of the sealing cavity 21 is high, opening the flow holes 221 on the sealing seat 22, thereby increasing the flow area and reducing the temperature of the sealing cavity 21. When the area of the bushing 222 is at its maximum, that is, when the axial dimension of the bushing 222 is at its maximum, the bushing 222 can completely cover all the flow holes 221 provided on the sealing seat 22, and the flow holes 221 are in a completely closed state, at which time the flow area of the flow holes 221 is 0. When the area of the bushing 222 is at its minimum, that is, when the axial dimension of the bushing 222 is at its minimum, the bushing 222 can completely open all the flow holes 221 provided on the sealing seat 22, and the flow holes 221 are in a completely open state, at which time the flow area of the flow holes 221 is at its maximum.
[0036] In some embodiments, in order to allow the flow area of the flow hole 221 to gradually change with the changing area of the bushing 222, i.e., the area of the portion made of shape memory alloy, the flow hole 221 is a regular shape extending along the axial direction. The shape of the flow hole 221 includes square, square-round, elliptical, wavy, continuously bent, etc., so that the flow area of the flow hole 221 can gradually decrease or gradually increase during the temperature change of the bushing 222 area, so as to ensure that the temperature and sealing pressure difference of the sealing cavity 21 tend to be stable and do not increase or decrease suddenly. This is beneficial to ensure the sealing of the bearing cavity 1 and the safe operation of the bearing in the bearing cavity 1, and can avoid the bearing cavity 1 from overheating or the bearing temperature from being too high, thereby avoiding bearing failure, oil carbon deposits and coking on the inner wall of the bearing cavity 1.
[0037] In some embodiments, to allow the flow area of the flow hole 221 to gradually change with the changing area of the bushing 222, the flow hole 221 includes a plurality of flow holes 221, which are evenly spaced along the axial direction. The shapes of the flow holes 221 include square, squarish-round, circular, triangular, etc. In some embodiments, the opening area of the flow hole 221 is 10 cm². 2 ~30cm 2 In some embodiments, to ensure that the temperature and sealing pressure difference of the sealing cavity 21 tend to stabilize, the opening area of the flow hole 221 is 15 cm². 2 ~25cm 2 In some embodiments, to ensure that the temperature and sealing pressure difference of the sealing cavity 21 tend to be stable, the spacing of the plurality of flow holes 221 arranged along the axial direction is smaller than the axial dimension of a single flow hole 221.
[0038] In some embodiments, such as Figure 4As shown, to facilitate lightweight design of the aero-engine structure and minimize the weight of the bushing 222, the bushing 222 is only installed in the area where the sealing seat 22 has an opening. In some embodiments, the flow hole 221 includes multiple rows of flow holes 221 arranged axially, and the bushing 222 includes multiple bushings 222, which are correspondingly arranged with respect to the multiple rows of flow holes 221. In some embodiments, one row of the multiple rows of flow holes 221 includes a plurality of flow holes 221 evenly spaced axially, and any one of the multiple bushings 222 has an axially extending structure, with one bushing 222 corresponding to a row of a plurality of flow holes 221 evenly spaced axially. This is merely an example. Figure 4 As shown, the sealing seat 22 has four rows of flow holes 221 arranged along the axial direction. Each row includes two flow holes 221. According to the position of the flow holes 221, in order to minimize the weight of the parts, the bushing 222 is divided into a first bushing 2221 and a second bushing 2222. The first bushing 2221 and the second bushing 2222 are respectively set corresponding to two rows of flow holes 221. The second side of the bushing 222, which is opposite to the first side along the axial direction, responds to the temperature expansion and contraction of the sealing gas in the axial direction to adjust the flow area of the flow holes 221.
[0039] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification, especially for those skilled in the art. Furthermore, unless expressly stated in the claims, the order of elements and sequences, the use of numbers and letters, or other names in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of currently considered useful embodiments of the invention have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.
Claims
1. A seal structure comprising a seal cavity and a seal seat for defining the seal cavity, characterized in that, The sealing seat has a flow hole for sealing the gas flow, and a bushing is provided on the sealing seat. The first side of the bushing is fixed relative to the sealing seat. At least a portion of the bushing is made of a shape memory alloy, the deformation of which is controlled by the temperature of the sealing gas. The deformation of the shape memory alloy causes a change in the area of the at least portion of the bushing, such that the flow hole has at least two states, including a fully open state and a fully closed state.
2. The seal construction of claim 1, wherein The rate of change of the area of the at least portion of the bushing is 0% to 100% in the temperature range of 60°C to 350°C.
3. The seal construction of claim 1, wherein The bushing is fitted onto the outer side of the sealing seat opposite to the sealing cavity.
4. The seal construction of claim 1, wherein The bushing extends along the axial direction of the engine, and the bushing is fixed relative to the sealing seat on a first side along the axial direction. The area of the at least portion of the bushing varies along the axial direction. The flow area of the flow hole is inversely related to the area of the at least portion of the bushing. When the bushing area is at its maximum, the flow hole is in a completely closed state, and the flow area of the flow hole is 0.
5. The seal construction of claim 4, wherein, The flow hole has a shape that extends along the axial direction, and the shape of the flow hole includes square, square-round, elliptical, and wavy.
6. The seal structure of claim 4, wherein The flow hole includes a plurality of flow holes, which are uniformly arranged along the axial direction.
7. The seal structure according to claim 5 or 6, characterized in that The flow holes include multiple rows of flow holes arranged along the axial direction, and the bushings include multiple bushings, which are correspondingly arranged with respect to the multiple rows of flow holes.
8. The seal structure of claim 4, wherein The bushing is provided with a mounting flange on the first side, the mounting flange extends in a direction perpendicular to the axial direction, and the mounting flange is fixedly installed with the sealing seat.
9. An aeroengine comprising a bearing cavity, characterised in that, It also includes a sealing structure, an air duct, a compressor, and a low-pressure turbine for sealing the bearing cavity as described in any one of claims 1-8; The bleed-out pipeline is connected between the compressor and the sealing chamber, and the bleed-out pipeline guides the gas in the compressor to the sealing chamber; The sealing seat defining the sealing cavity is located close to the low-pressure turbine, and the sealing gas in the sealing cavity can flow to the low-pressure turbine through the flow hole provided on the sealing seat.