Turboshaft overspeed protection device and method, aircraft engine

Abstract

Provided are a turbine shaft overspeed protection device and method and an aero-engine. The overspeed protection device comprises a protection bearing for supporting a turbine shaft, the protection bearing comprising an outer ring, an inner ring and a roller structure arranged on the inner ring, an inner circumferential surface of the outer ring is a surface with a radial height variation, the inner circumferential surface comprises a first inner circumferential surface and a second inner circumferential surface, the second inner circumferential surface is closer to one side of the turbine shaft than the first inner circumferential surface, and the outer ring is connected with a support cone wall; the roller structure is arranged to not contact the outer ring when the turbine shaft is working, the second inner circumferential surface is located in a first direction of the first inner circumferential surface, the first direction is consistent with a moving direction of the shaft at a support position of the protection bearing after the shaft is broken, so that the second inner circumferential surface contacts the roller structure to form a temporary support structure after the shaft is broken. The device can make the low-pressure turbine shaft keep rotating on the axis after the shaft is broken by adding the protection bearing, and effectively avoid a non-contained destructive failure.

Description

Technical Field

[0001] This invention relates to the field of aero-engines, and more specifically to the field of shaft fracture. Background Technology

[0002] The low-pressure turbine shaft of an aircraft turbofan engine is an important shaft component that connects the low-pressure turbine and the low-pressure compression components. It is one of the longest and most important main shafts of the engine, characterized by its large torque transmission capacity and hollow, slender shape.

[0003] The turbine shaft is typically supported at two points, front and rear, with free rotation in the middle. The front bearing is close to the compressor, and the rear bearing is close to the turbine, bearing radial and axial loads through the bearing structure. In some cases, there is also a three-point support scheme, in which the turbine shaft is supported by three bearings: front, middle, and rear. The front bearing is close to the compressor end, the middle bearing is close to the combustion chamber area, and the rear bearing is close to the turbine.

[0004] In actual engine operation, shaft failure and fracture may occur. After shaft fracture, the low-pressure turbine loses load, the speed rises sharply, and the turbine disk may overspeed and rupture, which can lead to a containment accident in severe cases. Therefore, an overspeed protection device for the turbine shaft is needed to avoid the above problems.

[0005] For example, Chinese patent CN113047959A discloses an aircraft engine braking device. The device includes a load-bearing frame, a low-pressure shaft, a first braking component, and a second braking component. The low-pressure shaft includes a fan shaft and a low-pressure turbine shaft. The first braking component, mounted on the load-bearing frame, includes a first braking part and a second braking part. The second braking component includes a third braking part and a fourth braking part. When the shaft breaks, the low-pressure turbine shaft can be braked simultaneously through the friction between the first and third braking parts, and between the second and fourth braking parts, thereby reducing the turbine's rotational speed.

[0006] For example, Chinese patent CN116357404A discloses a braking structure for preventing turbine overspeed after a broken shaft in an aero engine. When a broken shaft accident occurs in an aero engine, the turbine rotor moves backward, and the wedge-shaped conical surface of the rear journal of the turbine rubs against the conical surface of the front edge of the bearing housing. The friction limits the speed of the turbine rotor, thereby achieving rapid braking of the turbine rotor.

[0007] All of the above solutions achieve rapid braking by adding friction components, which consume energy through friction.

[0008] However, in engines with only one bearing at the rear end of the low-pressure turbine, if the low-pressure turbine shaft breaks, the turbine rotor continues to rotate at high speed on this single bearing, which can easily lead to misalignment of the rotation axes. This misalignment prevents the necessary contact rubbing devices from achieving large-area contact, and the overspeed protection function cannot operate properly.

[0009] It is necessary to provide a turbine shaft over-rotation protection device to solve the above problems. Summary of the Invention

[0010] One object of the present invention is to provide a turbine shaft over-rotation protection device.

[0011] The turbine shaft overspeed protection device for achieving the above objectives includes a protective bearing for supporting the turbine shaft. The protective bearing includes an outer ring, an inner ring, and a roller structure disposed on the inner ring. The inner circumferential surface of the outer ring is a surface with a radial height variation. The inner circumferential surface includes a first inner circumferential surface and a second inner circumferential surface. The second inner circumferential surface is closer to the turbine shaft than the first inner circumferential surface. The outer ring is connected to a support cone wall. The roller structure is configured not to contact the outer ring when the turbine shaft is operating. The second inner circumferential surface is located in a first direction of the first inner circumferential surface. The first direction is consistent with the direction of shaft movement at the support of the protective bearing after shaft breakage, so that the second inner circumferential surface contacts the roller structure to form a temporary support structure after shaft breakage. The direction of movement is either axially rearward or axially forward.

[0012] In one or more embodiments, the inner circumferential surface of the outer ring is an inclined surface, and the axial component of the inclined surface toward the radially inner side is consistent with the direction of movement of the shaft at the support of the protective bearing after shaft fracture, so that the inclined surface contacts the roller structure to form a temporary support structure after shaft fracture.

[0013] In one or more embodiments, the roller structure is a tapered roller structure, wherein the inclination direction of the tapered rollers of the tapered roller structure is parallel to the inclined surface.

[0014] In one or more embodiments, the inner circumferential surface of the outer ring is a stepped surface.

[0015] In one or more embodiments, the overspeed protection device includes a plurality of protective bearings disposed at different locations on the turbine shaft.

[0016] In one or more embodiments, the overspeed protection device further includes a friction component.

[0017] Another object of the present invention is to provide a method for over-rotation protection of a turbine shaft, comprising the following steps:

[0018] A friction component is installed on the engine, and the aforementioned turbine shaft over-rotation protection device is installed on the axial front side or axial rear side of the friction component.

[0019] In one or more embodiments, the friction element is disposed on the rotor and / or stator.

[0020] In one or more embodiments, the friction element is disposed on the wheel.

[0021] In one or more embodiments, the friction element is disposed on the support cone wall.

[0022] Another object of the present invention is to provide an aircraft engine including the aforementioned turbine shaft overspeed protection device.

[0023] The aforementioned turbine shaft over-rotation protection device, by adding a protective bearing, enables the low-pressure turbine shaft to remain on the axis and continue rotating after it breaks, and ensures that the rotor-stator rubbing over-rotation protection system functions properly, preventing the low-pressure turbine rotor from experiencing non-enclosed destructive failures due to its inability to maintain stable rotation on the same axis under a single bearing support. Attached Figure Description

[0024] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0025] Figure 1 This is a schematic diagram of the protective bearing in a certain setting position;

[0026] Figure 2 This is a diagram showing the bearing status during normal shaft operation;

[0027] Figure 3 This is a diagram showing the condition of the bearing after the shaft breaks.

[0028] Figure 4 yes Figure 2 Enlarged view of section H in the middle;

[0029] Figure 5 yes Figure 3 Enlarged view of point P in the middle;

[0030] Figure 6 This is a schematic diagram of the inner circumference of the stepped outer ring. (Symbol markings explained)

[0031] 1 First bearing

[0032] 2 Second bearing

[0033] 5 turbine shafts

[0034] 6. Supporting Conical Wall

[0035] 10 Protect bearings

[0036] 11 Outer Ring

[0037] 12 Inner Ring

[0038] 13 Roller Structure

[0039] 110 Inner circumferential surface

[0040] 111 First inner circumferential surface

[0041] 112 Second inner circumferential surface

[0042] 200 Friction Components

[0043] S-axis

[0044] R radial

[0045] Axial rear side

[0046] B-axis forward side

[0047] N-axis fracture point

[0048] G gap Detailed Implementation

[0049] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0050] It should be noted that these and other accompanying drawings are merely examples and are not drawn to scale, and should not be construed as limiting the scope of protection of the present invention.

[0051] An aero engine consists of components arranged sequentially along the airflow direction, including the air intake, fan, compressor, combustion chamber, turbine, and exhaust nozzle. Among these, the compressor, combustion chamber, and turbine form the core engine.

[0052] The intake duct and fan direct airflow into the compressor. The compressor, consisting of a low-pressure compressor and a high-pressure compressor, compresses air stage by stage using multi-stage rotating blades, increasing the air pressure and temperature to provide a high-energy working medium for subsequent combustion. The high-pressure air mixes with injected fuel in the combustion chamber and burns stably, releasing a large amount of heat energy, causing a rapid increase in air temperature and volume, forming a high-energy airflow. As the high-temperature, high-pressure gas passes through the turbine, it drives the turbine blades to rotate. The turbine extracts energy from the gas and drives the compressor and fan ahead via a coaxial connection. The remaining gas expands through the exhaust nozzle and is ejected at high speed, generating thrust.

[0053] The engine shaft is a force-transmitting device that connects various rotor components, such as the fan, compressor, and turbine, and also serves a positioning and support function through its cooperation with bearings and the casing. Different engines have different support structures.

[0054] For example, some engines use a two-point support scheme, that is, the rotor is supported by two bearings in the axial direction, forming a 1-1-0 or 0-2-0 support structure.

[0055] Some engines use a three-point support scheme, with one support point at the front and one at the rear of the compressor rotor, and one support point in front of the turbine disk, forming a 1-2-0 support structure. In addition, there is also a 0-2-1 three-point support scheme.

[0056] Some engines also use a five-point support scheme, such as the low-pressure rotor using a 1-2-0 scheme and the high-pressure rotor using a 0-2-0 scheme, which achieves effective support for the shaft through multi-point support.

[0057] For example, Figure 1 A support structure for an engine rotor is shown, including a first bearing 1 and a second bearing 2, which are respectively disposed at the front and rear ends of the rotor and together support the turbine shaft 5.

[0058] In the attached diagram, S represents the axial direction, and R represents the radial direction. The side closer to the axial direction S is called the radial inner side, and the side farther from the axial direction S is called the radial outer side. The direction forward along the axial direction is the axial front side B, and the direction backward along the axial direction is the axial rear side A.

[0059] After a shaft breaks, the shaft is prone to misalignment. In particular, if the area of ​​the broken shaft is supported by only a single bearing, it is more likely to cause misalignment of the rotating axis, making the original friction protection scheme unable to function properly and easily causing very serious consequences.

[0060] like, Figure 1 After the turbine shaft 5 breaks at the fracture point N, the shaft is divided into a front shaft and a rear shaft. The rear shaft is supported only by the second bearing 2, and the front shaft is supported only by the first bearing 1. This can easily lead to the problem of misalignment of the rotation axis, which causes the original friction area to shift and fails to achieve the rubbing function well.

[0061] Therefore, it is necessary to provide effective over-rotation protection to prevent shaft breakage and to prevent single bearing rotation after decoupling of the low-pressure turbine and low-pressure compression components, so as to ensure the normal operation of the rubbing protection scheme.

[0062] The turbine shaft overspeed protection device of the present invention adds a bearing protection structure, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the protective bearing 10 includes an outer ring 11, an inner ring 12, and a roller structure 13 disposed on the inner ring 12.

[0063] The outer ring 11 is connected to a supporting conical wall 6. The inner circumferential surface 110 of the outer ring 11 is a surface with a radial height variation, that is, the inner circumferential surface is not parallel to the axial direction S, but has different radial heights.

[0064] Specifically, the inner circumferential surface 110 includes a first inner circumferential surface 111 and a second inner circumferential surface 112, with the second inner circumferential surface 112 being closer to the turbine shaft 5 than the first inner circumferential surface 111.

[0065] In some embodiments, the inner peripheral surface 110 is Figure 4 and Figure 5 The inclined surface shown; in other embodiments, the inner circumferential surface is Figure 6 The step surface shown.

[0066] Back Figure 4 As shown, the roller structure 13 is configured to not contact the outer ring 11 when the turbine shaft is working, and has a gap G. That is, when the turbine shaft is working normally, the roller structure 13, the inner ring 12 and the turbine shaft 5 rotate synchronously to form an integral structure.

[0067] The second inner circumferential surface 112 of the outer ring 11 is disposed in a first direction of the first inner circumferential surface 111. The first direction is consistent with the direction of movement of the shaft at the support of the protective bearing after shaft fracture, so that the second side of the shaft contacts the roller structure to form a temporary support structure after shaft fracture.

[0068] The direction of shaft movement is either axial forward or axial backward.

[0069] For example, in Figures 2 to 5 In the illustrated embodiment, the bearing is positioned at the rear end of the turbine shaft. After shaft breakage, the turbine shaft 5 at the rear end moves substantially axially backward along the axial direction S towards the axial rearward side A. The second inner circumferential surface 112 is located axially backward of the first inner circumferential surface 111. Thus, when the shaft breaks, the freely rotating low-pressure turbine shaft will shift backward, and the roller structure 13 will contact the second inner circumferential surface 112 near the radially inner side of the inner circumferential surface of the outer ring. Figure 5 As shown, this forms an additional temporary bearing, which protects the bearing 10 together with the original second bearing 2, maintains the stable rotation of the shaft, prevents the single bearing from rotating after the low-pressure turbine and the low-pressure compression component are decoupled, avoids the problem of misalignment of the rotation axis, and thus ensures the normal operation of the rubbing structure.

[0070] It is understood that in the embodiment shown in the attached figures, the shaft fracture point N is located in the middle, and the shaft moves axially to the rear, with the protective bearing 10 positioned at the rearmost end of the low-pressure rotor. In other embodiments, the protective bearing 10 may be positioned at other locations depending on the original shaft support scheme and the direction of movement after the turbine shaft fracture.

[0071] For example, when the shaft fracture point is located in the middle and the shaft in front moves along the axial front side B, the protective bearing is set near the position of the first bearing 1 supporting the fractured shaft, and the second inner circumferential surface 112 is set on the axial front side of the first inner circumferential surface 111. In this way, after the shaft fractures, the turbine shaft moves generally along the axial direction S towards the axial front side B, and the roller structure 13 gradually approaches and contacts the second inner circumferential surface 112 of the outer ring to form a temporary bearing, maintaining the stable rotation of the shaft.

[0072] Therefore, it can be understood that for multi-point shafts, the over-rotation protection device includes multiple protective bearings located at different positions on the turbine shaft to quickly provide auxiliary support after shaft breakage and prevent the broken shaft from becoming eccentric.

[0073] When the inner circumference of the outer ring is Figure 4 When the inclined plane is shown, the axial component Ns of the radially inward tilt direction N of the inclined plane is consistent with the direction of movement of the shaft at the support of the protective bearing after the shaft breaks, that is, the axial rear side A, so that the inclined plane contacts the roller structure after the shaft breaks to form a temporary support structure.

[0074] When the inner circumference of the outer ring is Figure 6 When the stepped surface is shown, the second inner circumferential surface 112' is located on the axial rear side of the first inner circumferential surface 111'.

[0075] Roller structure 13 includes, but is not limited to, the tapered roller bearing shown in the figure.

[0076] When the roller structure 13 is a tapered roller bearing, the inclination direction of the tapered rollers in the tapered roller structure can be set to be parallel to the bearing surface. Figure 4 The inclined inner circumferential surface of the outer ring shown is parallel.

[0077] After the low-pressure turbine shaft breaks, the aforementioned turbine shaft over-rotation protection device allows the freely rotating low-pressure turbine rotor to continue rotating under the support of the original support bearing and the added retaining bearing. This prevents the low-pressure turbine from rotating under a single bearing after decoupling from the low-pressure compression component, and maintains the low-pressure turbine rotor's stable rotation on its own axis. This avoids the problem of misalignment of the rotation axis under a single bearing support after the turbine shaft breaks.

[0078] Furthermore, after the low-pressure turbine shaft breaks, the bearing itself can provide a certain frictional reduction effect.

[0079] Based on the above description of the turbine shaft over-rotation protection device, a turbine shaft over-rotation protection method can also be understood, which includes the following steps: a friction component 200 is installed on the engine, and the above turbine shaft over-rotation protection device is installed on the axial front side B or axial rear side A of the friction component 200.

[0080] In some embodiments, the friction member 200 is disposed on the rotor and / or stator, on the wheel disk, or on the support cone wall.

[0081] Reference Figure 1 It is understood that, if a friction component 200 is installed on the support cone wall, the protection bearing 10 of the over-rotation protection device can be installed in the second direction of the friction component 200, that is, the direction of movement after the shaft breaks, i.e., the axial rear side A.

[0082] In this way, with the added protective bearing 10 supporting it, the low-pressure turbine shaft continues to rotate stably, ensuring that the friction component 200 plays a normal role in reducing the rotational speed through friction, thereby limiting the turbine rotor speed and achieving rapid braking of the turbine rotor.

[0083] It should be noted that the use of terms such as "first" and "second" to define the components in the above content is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

[0084] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0085] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0086] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A turbo-shaft overspeed protection device, characterized in that, Comprising: A protection bearing for supporting a turbine shaft, the protection bearing comprising an outer ring, an inner ring and a roller structure arranged on the inner ring, an inner peripheral surface of the outer ring being a surface with a radial height variation, the inner peripheral surface comprising a first inner peripheral surface and a second inner peripheral surface, the second inner peripheral surface being closer to a side of the turbine shaft than the first inner peripheral surface, the outer ring being connected with a support cone wall; Wherein the roller structure is arranged to not contact the outer ring during operation of the turbine shaft, the second inner peripheral surface is located in a first direction of the first inner peripheral surface, the first direction being consistent with a moving direction of the shaft at the protection bearing supporting position after shaft fracture, so that the second inner peripheral surface contacts the roller structure to form a temporary supporting structure after shaft fracture, The moving direction is an axial rear side or an axial front side.

2. The turbine shaft overspeed protection device of claim 1, wherein The inner peripheral surface of the outer ring is a slope surface, a component of an inclination direction of the slope surface to a radial inner side in an axial direction is consistent with the moving direction of the shaft at the protection bearing supporting position after shaft fracture, so that the slope surface contacts the roller structure to form a temporary supporting structure after shaft fracture.

3. The turbine shaft overspeed protection device of claim 2, wherein The roller structure is a conical roller structure, an inclination direction of a conical roller of the conical roller structure is parallel to the slope surface.

4. The turbine shaft overspeed protection device of claim 1, wherein The inner peripheral surface of the outer ring is a stepped surface.

5. The turbine shaft overspeed protection device of claim 1, wherein The overspeed protection device comprises a plurality of protection bearings arranged at different positions of the turbine shaft.

6. The turbine shaft overspeed protection device of claim 1, wherein The overspeed protection device further comprises a friction component.

7. A method of turbo-shaft overspeed protection, characterized in that, Comprising the following steps: Arranging a friction component on the engine, Arranging the turbine shaft overspeed protection device according to any one of claims 1-6 on an axial front side or an axial rear side of the friction component.

8. The turbine shaft overspeed protection method of claim 7 wherein, Arranging the friction component on a rotor and / or a stator.

9. The turbine shaft overspeed protection method of claim 7 wherein, Arranging the friction component on a wheel disc.

10. The turbine shaft overspeed protection method of claim 7 wherein, Arranging the friction component on a support cone wall.

11. An aeroengine characterised in that, Comprising the turbine shaft overspeed protection device according to any one of claims 1-6.

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