A brake structure for preventing turbine fly-off after a shaft break of an aero-engine

Abstract

The application belongs to the field of safety design of aero-engines, and discloses a brake structure for preventing turbine fly-off after shaft breakage of an aero-engine, which is located between a low-pressure turbine and a turbine rear load-bearing frame, the rear side of a turbine rear shaft neck is fixedly connected with a short drum cylinder, the short drum cylinder is annular, the radial inner side of the short drum cylinder is spaced apart from the low-pressure turbine shaft and is coaxially arranged with the low-pressure turbine shaft; in the axial direction, the rear end of the short drum cylinder is spaced apart from the rigid bearing seat; after the low-pressure turbine shaft breaks, the low-pressure turbine moves backward, friction occurs between the rear end of the turbine rear shaft neck and the rigid bearing seat, the rotation speed of the low-pressure turbine is limited, and the low-pressure turbine is braked, the application realizes rapid braking and rebound limiting of turbine fly-off of the aero-engine, guarantees the integrity of the turbine component structure, prevents secondary accidents, and has high safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of safety design of aero-engine, and particularly relates to a brake structure for preventing turbine fly-off after shaft breakage of an aero-engine. BACKGROUND

[0002] Turbine fly-off is a severe and complex accident for an aero-engine. During normal operation of the aero-engine, the low-pressure turbine shaft breaks due to extreme load, machining and assembly, fatigue, jamming or other factors. After the low-pressure turbine shaft breaks, the low-pressure rotor loses load and increases in speed under the drive of the gas. When the turbine speed increases to a certain level, the turbine blades break, impact the casing, and the turbine disc also breaks due to excessive centrifugal stress, and the high-energy fragments can hit the aircraft, seriously affecting the safety of the aircraft. Therefore, it is necessary to design a brake structure for preventing turbine fly-off after shaft breakage of an aero-engine.

[0003] In order to reduce the harm caused by turbine fly-off, the traditional method is to actively control by monitoring the rotor speed and stopping fuel supply. However, this method has the disadvantage that the monitoring device stops fuel supply only after the engine rotor fly-off is detected. At the moment of stopping fuel supply, there is still fuel in the oil pipe, and the engine rotor still continues to rotate, which makes the speed of the engine rotor system faster and faster, and causes an irreversible secondary accident. Stopping fuel supply cannot immediately stop the driving force of the rotor system, and this process has a time delay. With the development of technology, this active control brake technology is no longer applicable in modern aero-engines, and therefore it is necessary to design a brake structure for passive control to prevent turbine fly-off.

[0004] After the low-pressure rotor of the aero-engine breaks, the low-pressure turbine impacts the load-bearing frame under the drive of the gas. However, the load-bearing frame is elastic, and the turbine rotor rebounds after impacting the load-bearing frame. The rebound of the engine turbine rotor after impacting the load-bearing frame causes collision and friction between the low-pressure turbine and other static structures. In the case of high speed, it can cause a secondary accident and damage the structural integrity of the engine. Therefore, it is necessary to design a rebound limiting structure after shaft breakage of the aero-engine to improve the safety of the engine. SUMMARY

[0005] To solve the above technical problems, the present application provides a brake structure for preventing turbine fly-off after shaft breakage of an aero-engine to solve the problems in the prior art. To achieve the above-mentioned application purposes, the technical scheme adopted by the present application is as follows:

[0006] The application discloses a brake structure for preventing turbine fly-off after broken shaft of an aero-engine, which is applied to the aero-engine and located between a low-pressure turbine and a turbine rear load-bearing frame.

[0007] The rear side of the turbine rear shaft neck is fixedly connected with a short drum cylinder, the short drum cylinder is annular, the inner side of the short drum cylinder is spaced apart from the low-pressure turbine shaft and coaxially arranged with the low-pressure turbine shaft; and the rear end of the short drum cylinder is spaced apart from the rigid bearing seat in the axial direction.

[0008] When the low-pressure turbine shaft is broken, the low-pressure turbine moves backward, friction occurs between the rear end of the turbine rear shaft neck and the rigid bearing seat, the rotation speed of the low-pressure turbine is limited and the low-pressure turbine is braked.

[0009] Further, the rear end of the short drum cylinder is provided with a wedge-shaped taper surface, the rigid bearing seat comprises a front edge taper surface which is matched with the wedge-shaped taper surface and corresponds in position, the wedge-shaped taper surface and the front edge taper surface are both taper surfaces and are spaced apart.

[0010] Further, the wedge-shaped taper surface is annularly provided with a first friction part, and the front edge taper surface is annularly provided with a second friction part, the first and second friction parts are used for increasing friction force when being contacted.

[0011] Further, the first friction part is a first convex tooth fixedly arranged on the wedge-shaped taper surface, and the second friction part is a second convex tooth fixedly arranged on the front edge taper surface.

[0012] Further, the rigid bearing seat further comprises an axial stop edge arranged at the front end of the front edge taper surface, the outer side of the short drum cylinder is provided with an annular groove matched with the axial stop edge, and the inner side of the rear end of the short drum cylinder is fixedly provided with a convex block.

[0013] When the low-pressure turbine shaft is broken, the rotation speed of the low-pressure turbine is increased, the short drum cylinder is deformed in the radial direction, the radial spacing between the short drum cylinder and the axial stop edge of the front end of the rigid bearing seat is reduced, the annular groove is nested on the axial stop edge and is locked with each other, so that the low-pressure turbine is axially limited, the function of rebound limiting of the low-pressure turbine is realized, and the convex block is used for increasing the radial deformation amount of the short drum cylinder.

[0014] Further, the rigid bearing seat further comprises a bearing mounting part, a force transmission taper shell and a fixed mounting edge which are sequentially arranged, the front edge taper surface is located at the front end of the bearing mounting part, the outer ring of the fulcrum bearing is mounted on the inner side of the bearing mounting part in the radial direction, the force transmission taper shell is obliquely arranged, and the rear end of the fixed mounting edge is connected with the turbine rear load-bearing frame.

[0015] Further, the turbine rear axle neck comprises a mortise mounting edge and an axle neck, the rear side of the axle neck is fixedly connected to the front end of the short drum, the radial outer side of the axle neck is fixedly connected to the mortise mounting edge, and the mortise mounting edge is detachably connected to the low-pressure turbine.

[0016] Further, the radial inner side of the axle neck is connected to the low-pressure turbine shaft through a sleeve-tooth coupling.

[0017] Further, a groove is formed between the radial inner side of the axle neck and the radial outer side of the low-pressure turbine shaft, the sleeve-tooth coupling is located in the groove, the rear end of the axle neck abuts against the front end face of the fulcrum bearing, the rear end face of the fulcrum bearing abuts against a nut, and the nut is sleeved on the low-pressure turbine shaft.

[0018] An aero-engine comprises three-stage fans arranged in sequence from front to back, an intermediate load-bearing frame, five-stage high-pressure compressors, an annular combustion chamber, a first-stage high-pressure turbine, a turbine inter-stage load-bearing frame, a two-stage low-pressure turbine and a turbine rear load-bearing frame, and the brake structure is located between the low-pressure turbine and the turbine rear load-bearing frame.

[0019] The present application has the following advantages: the wedge-shaped conical surface of the turbine rear axle neck and the front edge conical surface of the bearing seat are adopted to realize the rapid braking and rebound limiting of the turbine flywheel of the aero-engine. When the aero-engine is normally operated, the wedge-shaped conical surface of the turbine rear axle neck and the front edge of the bearing seat have a gap and do not contact and rub. When the aero-engine has an axle break accident, the turbine rotor moves backward, the wedge-shaped conical surface of the turbine rear axle neck rubs against the front edge conical surface of the bearing seat, the turbine rotor speed is limited through the friction, and the rapid braking of the turbine rotor is realized. The turbine impacts the rigid bearing seat backward and rebounds, the turbine rebound is limited through the axial stop edge and the ring groove, the integrity of the turbine component structure is ensured, the occurrence of secondary accidents is prevented, and high safety is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a structural diagram of a typical dual-rotor high-thrust-to-weight-ratio turbofan aero-engine in the present application.

[0021] Figure 2 It is a structural diagram of a typical dual-rotor high-thrust-to-weight-ratio turbofan aero-engine in the present application. Figure 1 It is a partial structural diagram of the low-pressure turbine and the turbine rear load-bearing frame.

[0022] Figure 3 It is a partial structural diagram of the low-pressure turbine and the turbine rear load-bearing frame. Figure 2 It is an enlarged view of a partial structure at A.

[0023] Figure 4 It is an enlarged view of a partial structure at B. Figure 3 It is an enlarged view of the brake structure at B.

[0024] Figure 5For Figure 4 Cross-sectional view of the ring at C;

[0025] Figure 6 For the brake structure after the turbine fly of the application.

[0026] Figure 7 For Figure 6 Cross-sectional view of the ring at D. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the application will be clearly and completely described below Figures 1-7 The technical solutions in the embodiments of the application will be clearly and completely described below

[0028] It should be noted that the accompanying Figures 1-7 For the cross-sectional view, the low-pressure turbine shaft 90, the toothed coupling 2, the turbine rear journal 1, the low-pressure turbine 97 and the fulcrum bearing 4 in the application are coaxial rotating structures, referred to as a low-pressure turbine rotor system, which is referred to as a rotor system in this paper; the rigid bearing seat 3 and the turbine rear load-bearing frame 98 are coaxial non-rotating structures, referred to as a stator system. Figure 1 And Figure 6 The arrow in the figure indicates the moving direction of the low-pressure turbine 97 after the low-pressure turbine shaft 90 breaks.

[0029] In addition, "radial" in the application refers to the up-down direction in the figure, "radial outer side" refers to the position of the component on the upper side, i.e., the side away from the low-pressure turbine shaft 90; "radial inner side" refers to the position of the component on the lower side, i.e., the side close to the low-pressure turbine shaft 90; "front end" refers to the left side in the axial direction in the figure, and "rear end" refers to the right side in the axial direction in the figure, the "front end" and the "rear end" are defined according to the intake and exhaust directions of the engine, and according to the industry convention, the engine intakes air at the front end and exhausts air at the rear end.

[0030] As Figure 1 , a specific structure of a typical dual-rotor high-thrust-to-weight-ratio turbofan aero-engine 9, which includes, from front to back, a three-stage fan 91, an intermediate load-bearing frame 92, a five-stage high-pressure compressor 93, an annular combustor 94, a first-stage high-pressure turbine 95, a turbine inter-stage load-bearing frame 96, a two-stage low-pressure turbine 97 and a turbine rear load-bearing frame 98, the brake structure is located between the low-pressure turbine 97 and the turbine rear load-bearing frame 98, and the low-pressure turbine 97 is a two-stage low-pressure turbine.

[0031] The brake structure for preventing turbine flywheel of the application is designed between the low-pressure turbine 97 and the turbine rear supporting frame 98, that is, the main purpose of the application is to design the brake structure for preventing flywheel for the two-stage low-pressure turbine.

[0032] As Figure 2 A brake structure for preventing turbine flywheel after shaft breakage of an aero-engine is applied to the aero-engine 9, and is located between the low-pressure turbine 97 and the turbine rear supporting frame 98. The rear end of the low-pressure turbine 97 is fixedly provided with a turbine rear journal 1, the turbine rear journal 1 is connected with a low-pressure turbine shaft 90, a fulcrum bearing 4 is installed on the low-pressure turbine shaft 90, and the fulcrum bearing 4 is connected with the turbine rear supporting frame 98 through a rigid bearing seat 3.

[0033] The rear side of the turbine rear journal 1 is fixedly connected with a short drum 13, the short drum 13 is annular, is spaced apart and arranged coaxially with the low-pressure turbine shaft 90 between the radial inner side of the short drum 13 and the low-pressure turbine shaft 90, and is gap-distributed between the rear end of the short drum 13 and the rigid bearing seat 3 in the axial direction.

[0034] When the low-pressure turbine shaft 90 breaks, the low-pressure turbine 97 moves backward, friction occurs between the rear end of the turbine rear journal 1 and the rigid bearing seat 3, the rotation speed of the low-pressure turbine 97 is limited, and the brake is achieved.

[0035] The low-pressure turbine 97 and the turbine rear supporting frame 98 are both prior art structures of the aero-engine 9, the rotating part turbine rear journal 1 and the non-rotating part rigid bearing seat 3 are located between the low-pressure turbine 97 and the turbine rear supporting frame 98, the turbine rear journal 1 is located at the rear end of the low-pressure turbine 97, and the rigid bearing seat 3 is located between the radial inner side of the turbine rear supporting frame 98 and the low-pressure turbine shaft 90.

[0036] As Figure 6 And Figure 7 The application designs a reserved gap between the rear end of the short drum 13 and the rigid bearing seat 3. When the low-pressure turbine shaft 90 breaks, the rotating parts, i.e., the low-pressure turbine 97, the turbine rear journal 1 and the low-pressure turbine shaft 90, move backward under the action of aerodynamic force, and the rotation speed increases under the driving of the gas because of the loss of load. At this time, the short drum 13 contacts the rigid bearing seat 3 to generate sliding friction, so as to slow down and achieve the purpose of rapid brake.

[0037] Reference Figure 3 , Figure 4, the turbine rear axle neck 1 as a whole comprises an integral formed stop mounting edge 11, an axle neck 12, a short drum 13 and a wedge-shaped taper surface 14, the short drum 13 is provided with the wedge-shaped taper surface 14 at the rear end, the rigid bearing seat 3 comprises a front edge taper surface 32 which is matched with the wedge-shaped taper surface 14 and positionally corresponds, the wedge-shaped taper surface 14 and the front edge taper surface 32 are both taper surface structures, and the gap between them is distributed.

[0038] Specifically, the wedge-shaped taper surface 14 is an annular taper surface, the outer diameter of which gradually shortens from front to back, and the front edge taper surface 32 is also an annular structure, the radial spacing between which and the low-pressure turbine shaft 90 gradually shortens from front to back, after the low-pressure turbine shaft 90 breaks, the wedge-shaped taper surface 14 and the front edge taper surface 32 will be in contact and friction, achieving rapid braking.

[0039] Further, the wedge-shaped taper surface 14 is annularly provided with a first friction part, and correspondingly, the front edge taper surface 32 is annularly provided with a second friction part, the first and second friction parts are used to increase the friction force when in contact.

[0040] Further, the first friction part is a first protruding tooth 141 fixedly arranged on the wedge-shaped taper surface 14, and the second friction part is a second protruding tooth 321 fixedly arranged on the front edge taper surface 32.

[0041] The first and second protruding teeth are annularly and uniformly distributed, and the purpose of the two is to increase the sliding friction force and to mesh to form a certain rotation limit, so that the rotor system can rapidly brake.

[0042] Further, the rigid bearing seat 3 further comprises an axial stop edge 31 arranged at the front end of the front edge taper surface 32, the radial outer side of the short drum 13 is provided with an annular groove 131 matched with the axial stop edge 31, and the rear end of the short drum 13 is fixedly provided with a protruding block 142 on the radial inner side.

[0043] When the low-pressure turbine shaft 90 breaks, the speed of the low-pressure turbine 97 increases, the short drum 13 deforms radially, the radial spacing between the short drum 13 and the axial stop edge 31 at the front end of the rigid bearing seat 3 decreases, the annular groove 131 is nested on the axial stop edge 31 and is mutually stuck, thereby axially limiting the low-pressure turbine 97, achieving the function of rebound limiting of the low-pressure turbine 97, and the protruding block 142 is used to increase the radial deformation amount of the short drum 13.

[0044] The axial stop 31 forms a protruding structure at the front end of the front edge cone surface 32, and the ring groove 131 is radially opposite to the axial stop 31 and has a certain gap, and the radial deformation of the short drum cylinder 13 is smaller than the gap during normal operation of the engine; after the low-pressure turbine shaft 90 breaks, the turbine rotor moves backward under the action of aerodynamic force and flies, and rebounds after impacting the rigid bearing seat 3, and the radial deformation of the short drum cylinder 13 increases due to the flight, and the ring groove 131 and the axial stop 31 are mutually stuck, thereby achieving rebound limiting of the low-pressure turbine.

[0045] Reference Figure 3 、 Figure 4 The rigid bearing seat 3 integrally includes an axial stop 31, a front edge cone surface 32, a bearing mounting portion 33, a force transmission cone shell 34 and a fixed mounting edge 35, the front edge cone surface 32 is located at the front end of the bearing mounting portion 33, the bearing outer ring 41 of the fulcrum bearing 4 is mounted on the radially inner side of the bearing mounting portion 33, the force transmission cone shell 34 is obliquely arranged, and the rear end of the fixed mounting edge 35 is connected with the turbine rear force bearing frame 98.

[0046] Specifically, the bearing mounting portion 33 is parallel to the low-pressure turbine shaft 90, the force transmission cone shell 34 is obliquely arranged, and the radially outer side of the fixed mounting edge 35 is connected with the mounting edge 981 of the turbine rear force bearing frame 98 through bolts.

[0047] Further, the front end of the short drum cylinder 13 is fixedly connected to the rear side of the shaft journal 12, and the radially outer side of the shaft journal 12 is fixedly connected to the stop mounting edge 11, and the stop mounting edge 11 is detachably connected with the low-pressure turbine 97.

[0048] Specifically, the stop mounting edge 11 on the radially outer side of the turbine rear shaft journal 1 is connected with the flange edge 971 of the low-pressure turbine 97 and the mounting edge 51 of the sealing structure 5 through bolts 6.

[0049] Further, the radially inner side of the shaft journal 12 is connected with the low-pressure turbine shaft 90 through the toothed sleeve coupling 2.

[0050] Further, a groove body is formed between the radially inner side of the shaft journal 12 and the radially outer side of the low-pressure turbine shaft 90, the toothed sleeve coupling 2 is located in the groove body, the rear end of the shaft journal 12 abuts against the front end face of the fulcrum bearing 4, the rear end face of the fulcrum bearing 4 abuts against the nut 8, and the nut 8 is sleeved on the low-pressure turbine shaft 90.

[0051] Specifically, the bearing 4 comprises a bearing outer ring 41, a roller 42, a retainer 43 and a bearing inner ring 44, the bearing outer ring 41 is in abutment with the inner side of the bearing mounting portion 33, and the positioning installation of the bearing is realized through the bearing stop edge 7; the rear end of the bearing inner ring 44 is axially positioned through the nut 8, and the front end of the bearing inner ring 44 is in abutment with the rear end of the shaft neck 12 and rotates together with the low-pressure turbine shaft 90,

[0052] The shaft neck 12 is in an "L" shape structure, the inner side thereof is a long side, and is in a stepped structure, the radial outer side of the low-pressure turbine shaft 90 is provided with a corresponding stepped portion, the sleeve gear coupling 2 comprises a radial positioning surface one 21, a radial positioning surface two 24, an axial positioning surface 23 and a sleeve gear 22, the radial positioning surface one 21 and the radial positioning surface two 24 are used for ensuring the coaxial degree of the turbine rear shaft neck 1 and the low-pressure turbine shaft 90, the axial positioning surface 23 is used for the axial positioning installation of the turbine rear shaft neck 1, and the sleeve gear 22 transmits the torque by intermeshing. The sleeve gear 22 transmits the torque of the turbine to the compressor, the compressor consumes energy, after the shaft is broken, the energy consumption component is lost, the turbine continuously increases the rotating speed under the blowing of the gas, that is, the action of the aerodynamic force, and the turbine flywheel is caused.

[0053] The working principle of the brake structure for preventing the turbine flywheel in the application will be described below:

[0054] The wedge-shaped conical surface 14 and the front edge conical surface 32 are opposite to each other and have a certain gap, and no contact occurs during normal operation, the axial gap is smaller than the axial gap between the turbine rotor and the turbine stator, and it is ensured that when the low-pressure shaft 90 of the engine 9 is broken, the low-pressure turbine rotor moves backward, and the wedge-shaped conical surface 14 first contacts the front conical surface 32; the wedge-shaped conical surface 14 is provided with first protrusions 141, the front edge conical surface 32 is provided with second protrusions 321, the thickness of the first protrusions 141 and the second protrusions 321 is only 0.2-0.3 mm, and the main function is to increase the friction force when they contact each other, so that the low-pressure turbine rotor is rapidly braked.

[0055] The short drum 13 comprises circumferentially distributed through holes 132 and ring grooves 131; the through holes 132 are used for preventing the lubricating oil from being enriched on the inner ring surface of the short drum 13, the ring groove 132 is radially opposite to the axial stop edge 31 and has a certain gap, the radial deformation of the short drum 13 is smaller than the gap during normal operation of the engine; and after the low-pressure turbine shaft 90 is broken, the turbine rotor moves backward and flywheels under the action of the aerodynamic force, the turbine rotor rebounds after impacting the rigid bearing seat 3, the radial deformation of the short drum 13 increases due to the increase of the rotating speed, the ring groove 131 and the axial stop edge 31 are mutually clamped, and the rebound limiting of the low-pressure turbine is realized.

[0056] The wedge-shaped conical surface 14 is opposite to the leading edge conical surface 32, and does not contact in normal operation of the engine. After the low-pressure turbine shaft breaks and flies, the wedge-shaped conical surface 14 and the leading edge conical surface 32 are in contact and friction to realize the rapid braking of the low-pressure turbine rotor. Compared with other braking structures located at the turbine blade tip and the turbine disc rim, the braking structure between the turbine rear shaft neck 1 and the rigid bearing position 3 has a smaller radius, higher coaxiality, higher stability, and can appropriately reduce the radial amplitude of the turbine fly during braking, thereby ensuring the stable realization of the rapid braking of the fly turbine.

[0057] The above-described embodiments are only used to describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications, variations, modifications, and replacements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A brake structure for preventing turbine run away after a broken shaft of an aero-engine, applied on an aero-engine (9), characterized in that: The brake structure is located between the low-pressure turbine (97) and the turbine rear bearing frame (98), the rear end of the low-pressure turbine (97) is fixedly provided with a turbine rear shaft neck (1), the turbine rear shaft neck (1) is connected with a low-pressure turbine shaft (90), a fulcrum bearing (4) is installed on the low-pressure turbine shaft (90), and the fulcrum bearing (4) is connected with the turbine rear bearing frame (98) through a rigid bearing seat (3); The rear side of the turbine rear shaft neck (1) is fixedly connected with a short drum (13), the short drum (13) is annular, is spaced apart between the radial inner side and the low-pressure turbine shaft (90), and is coaxially arranged with the low-pressure turbine shaft (90); in the axial direction, the rear end of the short drum (13) is gap-distributed between the rigid bearing seat (3). When the low-pressure turbine shaft (90) is broken, the low-pressure turbine (97) moves backward, friction occurs between the rear end of the turbine rear shaft neck (1) and the rigid bearing seat (3), the rotation speed of the low-pressure turbine (97) is limited, and the low-pressure turbine (97) is braked; The rear end of the short drum (13) is provided with a wedge-shaped taper surface (14), the rigid bearing seat (3) comprises a front edge taper surface (32) which is matched with the wedge-shaped taper surface (14) and is in position correspondence, the wedge-shaped taper surface (14) and the front edge taper surface (32) are both taper surfaces, and the two are gap-distributed; The rigid bearing seat (3) further comprises an axial stop edge (31) arranged at the front end of the front edge taper surface (32), the radial outer side of the short drum (13) is provided with a ring groove (131) matched with the axial stop edge (31), and the rear end of the short drum (13) is fixedly provided with a protrusion (142) on the radial inner side; When the low-pressure turbine shaft (90) is broken, the rotation speed of the low-pressure turbine (97) increases, the short drum (13) is deformed in the radial direction, the radial spacing between the short drum (13) and the axial stop edge (31) at the front end of the rigid bearing seat (3) is reduced, the ring groove (131) is nested on the axial stop edge (31) and is locked with each other, so that the low-pressure turbine (97) is axially limited, the function of rebound limiting of the low-pressure turbine (97) is realized, and the protrusion (142) is used for increasing the radial deformation amount of the short drum (13).

2. A brake structure for preventing turbine runaway after a broken shaft of an aero-engine according to claim 1, characterized in that: The wedge-shaped taper surface (14) is annularly provided with a first friction part, and correspondingly, the front edge taper surface (32) is annularly provided with a second friction part, and the first and second friction parts are used for improving the friction force when being contacted.

3. A brake structure for preventing turbine runaway after a shaft break of an aero-engine according to claim 2, characterized in that: The first friction part is a first protrusion (141) fixedly arranged on the wedge-shaped taper surface (14), and the second friction part is a second protrusion (321) fixedly arranged on the front edge taper surface (32).

4. A brake structure for preventing turbine runaway after a shaft break of an aero-engine according to claim 1, characterized in that: The rigid bearing seat (3) further comprises a bearing mounting part (33), a force transmission taper shell (34) and a fixed mounting edge (35) arranged in sequence, the front edge taper surface (32) is located at the front end of the bearing mounting part (33), the bearing outer ring (41) of the fulcrum bearing (4) is mounted on the radial inner side of the bearing mounting part (33), the force transmission taper shell (34) is obliquely arranged, and the rear end of the fixed mounting edge (35) is connected with the turbine rear bearing frame (98).

5. A brake structure for preventing turbine runaway after a shaft break in an aeroengine according to claim 1, characterized in that: The turbine rear axle journal (1) comprises a socket mounting edge (11) and a journal (12), the rear side of the journal (12) is fixedly connected with the front end of the short drum (13), the radial outer side of the journal (12) is fixedly connected with the socket mounting edge (11), and the socket mounting edge (11) is detachably connected with the low-pressure turbine (97).

6. A brake structure for preventing turbine runaway after a shaft break in an aeroengine according to claim 5, characterized in that: The radial inner side of the journal (12) is connected with the low-pressure turbine shaft (90) through a sleeve gear coupling (2).

7. A brake structure for preventing turbine runaway after a shaft break in an aeroengine according to claim 6, characterized in that: The radial inner side of the journal (12) and the radial outer side of the low-pressure turbine shaft (90) form a groove, the sleeve gear coupling (2) is located in the groove, the rear end of the journal (12) abuts against the front end face of the fulcrum bearing (4), the rear end face of the fulcrum bearing (4) abuts against a nut (8), and the nut (8) is sleeved on the low-pressure turbine shaft (90).

8. An aeroengine incorporating a brake structure as claimed in any one of claims 1 to 7, characterised in that: The aero-engine (9) comprises, from front to back, three-stage fans (91), an intermediate load-bearing frame (92), five-stage high-pressure compressors (93), an annular combustion chamber (94), a first-stage high-pressure turbine (95), a turbine inter-stage load-bearing frame (96), a low-pressure turbine (97) and a rear turbine load-bearing frame (98), the brake structure is located between the low-pressure turbine (97) and the rear turbine load-bearing frame (98), and the low-pressure turbine (97) is a two-stage low-pressure turbine.

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