Design method of anti-unbalance load capacity for preventing intermediate bearing from sliding

Abstract

The application provides a design method for anti-unbalanced load capacity of preventing intermediate bearing from sliding, the method comprising: determining key design factors for preventing intermediate bearing from sliding, the key design factors comprising intermediate bearing tilt angle in assembled state, inner and outer ring tilt angle of intermediate bearing in working state, intermediate bearing tilt angle under gravity and intermediate bearing tilt angle under motor load; determining total tilt angle of intermediate bearing in working state, the total tilt angle of intermediate bearing in working state comprising total tilt angle of intermediate bearing in working state in bench state and total tilt angle of intermediate bearing in working state in flight state; judging whether the total tilt angle of intermediate bearing in working state meets the anti-sliding requirement, if the requirement is met, the design is ended, otherwise, the bearing installation structure is adjusted again until the requirement is met. The method of the application comprehensively considers the influence of various key factors, can effectively reduce the risk of intermediate bearing sliding, and improve the safety and reliability of intermediate bearing.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a design method for preventing slippage of intermediate bearings and thus enhancing their resistance to eccentric loads. Background Technology

[0002] To shorten the span of the pivot point and reduce the weight of aero engines, intermediate bearings are often placed between the high-pressure and low-pressure rotors during aero engine design. These intermediate bearings operate under various extreme conditions, including high speed, high temperature, variable load, and frequent lubricant contamination. Failure of an intermediate bearing can lead to rotor system failure, bearing seizure, or shaft breakage, ultimately resulting in loss of engine power and a major accident. A common failure mode for intermediate bearings is surface spalling, primarily caused by off-center loading during operation. This leads to excessive localized stress when the roller edges contact the raceway edges of the inner and outer rings, causing surface spalling and significantly reducing the bearing's lifespan. Therefore, a properly designed bearing with anti-off-center loading capabilities to prevent slippage is essential.

[0003] In existing technologies, the design of anti-eccentric load capacity to prevent bearing slippage only considers the influence of a single factor on the intermediate bearing, without comprehensively considering the combined effects of multiple influencing factors such as fulcrum coaxiality, radial clearance, rotor runout, assembly tightness, bolt tightening torque, working load, and rotor deflection on the design of anti-eccentric load capacity to prevent bearing slippage. This may lead to friction between the roller edge and the inner and outer raceways, affecting the service life of the bearing. Summary of the Invention

[0004] The purpose of this application is to provide a design method for anti-eccentric load capability to prevent intermediate bearing slippage, thereby avoiding slippage of the intermediate bearing during operation and thus better supporting the engine.

[0005] The technical solution of this application is: a design method for preventing slippage of intermediate bearings and enhancing anti-eccentric load capacity, the method comprising:

[0006] The key design factors for preventing intermediate bearing slippage are identified, including the intermediate bearing tilt angle in the assembled state, the tilt angle of the inner and outer rings of the intermediate bearing in the working state, the intermediate bearing tilt angle under gravity, and the intermediate bearing tilt angle under motor load.

[0007] Determine the total tilt angle of the intermediate bearing in the working state, which includes the total tilt angle of the intermediate bearing in the working state under test state and the total tilt angle of the intermediate bearing in the working state under flight state;

[0008] Determine whether the total tilt angle of the intermediate bearing under working conditions meets the anti-slip requirements. If it does, the design is complete; otherwise, readjust the bearing mounting structure until the requirements are met.

[0009] Furthermore, the intermediate bearing tilt angle λ in the assembled state 装配 for:

[0010]

[0011] In the formula, T w This refers to the runout of the outer ring of a four-point bearing.

[0012] T n It is a four-point inner circle jump.

[0013] L2 is the span of the three- or four-point bearing.

[0014] L3 represents the span of a four- or five-point bearing.

[0015] T5 indicates the coaxiality of a five-point bearing.

[0016] e is the tilt angle caused by the radial clearance of the five-point bearing.

[0017] Furthermore, the inner ring tilt angle γ of the intermediate bearing in the aforementioned working state n Outer ring tilt angle γ w Obtained through finite element analysis.

[0018] Furthermore, the tilt angle θ of the intermediate bearing under the action of gravity g for:

[0019]

[0020] In the formula, Δx 内 Due to the difference in deformation of the inner ring of the intermediate bearing,

[0021] L 内 For the inner ring length of the intermediate bearing,

[0022] Δx 外 Due to the difference in deformation of the inner ring of the intermediate bearing,

[0023] L 外 This refers to the length of the inner ring of the intermediate bearing.

[0024] Furthermore, the tilt angle of the intermediate bearing under the aforementioned motor load is:

[0025]

[0026] In the formula, F 角速度 This refers to the fulcrum load generated by the gyroscopic torque at the fulcrum under a unit angular velocity load when the engine is operating at its maximum speed.

[0027] F 重力 The magnitude of the load on the fulcrum under a gravitational load of 1g.

[0028] n is the normal overload.

[0029] θ g This refers to the tilt angle of the intermediate bearing under gravity load.

[0030] Furthermore, the total tilt angle of the intermediate bearing in the working state under the test bench condition is:

[0031]

[0032] Furthermore, the total tilt angle of the intermediate bearing in the flight state is:

[0033]

[0034] The anti-eccentric load design method for preventing intermediate bearing slippage provided in this application comprehensively considers the influence of various key factors, which can effectively reduce the risk of intermediate bearing slippage and improve the safety and reliability of intermediate bearings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0036] Figure 1 This is a flowchart illustrating the design method for preventing slippage of intermediate bearings in this application, specifically addressing off-center load resistance.

[0037] Figure 2 This is a schematic diagram of the high-pressure and low-pressure rotors of the aero-engine in this application, which are supported by five common support points.

[0038] Figure 3 This is a schematic diagram of the tilt angles of the inner and outer rings of the intermediate bearing in its working state as described in this application.

[0039] Figure 4 This is a schematic diagram of the bearing tilt angle under gravity in this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, the anti-eccentric load design method for preventing slippage of intermediate bearings provided in this application includes the following steps:

[0042] S1, Data Input

[0043] Obtain structural parameters and load data of intermediate bearings and their installation locations.

[0044] S2. Determine the tilt angle of the intermediate bearing in the assembled state.

[0045] like Figure 2 The diagram shown is a schematic of a certain type of aero-engine with high and low pressure rotors supported by five fulcrums in an embodiment of this application. The high pressure turbine rear journal is equipped with four fulcrum bearings (i.e., intermediate bearings) and supported on the low pressure turbine shaft.

[0046] In the assembled state, the skew angle of the four-point bearing is related to the skewness of the high and low pressure turbine rotor, the concentricity of the stator support points of the entire machine, the radial clearance of each bearing, and the rotor runout. In the cold, horizontally assembled state of the entire machine, the radial clearance of the second, third, and fourth-point bearings can be eliminated. Therefore, the skew angle of the four-point bearing can be calculated using the following formula: λ 装配 =β1 + β2. (1)

[0047] according to Figure 2 It can be seen that the inclination angle of the inner ring of the four-point bearing is β1 = β3 + β4. Substituting this into Equation 1 above, we can obtain:

[0048] λ 装配 =β2 + β3 + β4. (2)

[0049] In the above formula, the tilt angle caused by the runout of the outer ring of the four-point bearing is... T w L1 represents the runout of the outer ring of the four-point bearing, and L2 represents the span of the three-point and four-point bearings.

[0050] The tilt angle β3 caused by the coaxiality T5 and radial clearance e of the five-point bearing is the same as the tilt angle caused by the coaxiality of the two-point bearing, that is:

[0051]

[0052] In the formula, L1 is the span of the two- and five-point bearings, and L3 is the span of the four- and five-point bearings.

[0053] Tilt angle caused by runout of the inner ring of a four-point bearing T n It is a four-point inner circle jump.

[0054] Through the above process, the tilt angle of the intermediate bearing in the assembled state can be obtained as follows:

[0055]

[0056] S3. Determine the inclination angles of the inner and outer rings of the intermediate bearing under operating conditions.

[0057] like Figure 3 As shown, this diagram illustrates the tilt angles of the inner and outer rings of the bearing in its working state, with the intermediate bearing's inner tilt angle γ. n Outer ring tilt angle γ wIt mainly depends on the radial deformation difference of the raceway under centrifugal and temperature loads, and is also affected by factors such as the tightness of the contact surfaces of the inner and outer rings of the intermediate bearing with other components, the tightening torque of the bolt connections, the axial clearance and the working clearance. The tilt angle of the inner and outer rings of the bearing can be obtained through finite element analysis. Centrifugal load, temperature load, bolt tightening torque are applied in the model, and the contact tightness is set at the contact surface.

[0058] S4. Determine the tilt angle θg of the intermediate bearing under gravity.

[0059] like Figure 4 As shown, the deformation of the inner and outer rings of the intermediate bearing under gravity in test bench condition is calculated using the finite element method. The tilt angle of the intermediate bearing is obtained based on the front-to-back deformation difference Δx of its inner and outer rings and the length L of the inner and outer rings of the bearing, as shown in the following formula:

[0060] In Formula 5, the bearing inner ring tilt angle θ 内 The deformation difference Δx of the inner ring 内 L is calculated from the inner circle length. 内 ,Right now:

[0061] Bearing outer ring tilt angle θ 外 The deformation difference Δx of the outer ring 外 L is calculated from the outer ring length. 外 ,Right now

[0062]

[0063] In summary, the bearing tilt angle under gravity is:

[0064] S5. Determine the tilt angle of the intermediate bearing under mechanical load.

[0065] During flight, maneuvering occurs. In this application, the bearing tilt angle under the action of maneuvering loads is also considered to prevent the intermediate bearing from slipping.

[0066] Bearing tilt angle θ under motor load J This includes normal overload and angular velocity overload. Under engine operating conditions, during angular velocity overload, the load force is mainly generated by the gyroscopic torque. Under a unit angular velocity (ωz = 1 rad / s) load, the bearing tilt angle θ is [value missing] when the engine is operating at its maximum speed. 角 .

[0067] Tilt angle θ caused by normal overload 法 =n×θ g Where n is the normal overload load, θ g The tilt angle is the angle under a gravitational load of 1g. The tilt angle θg of the intermediate bearing under gravity can be referred to in step S4.

[0068] Under unit angular velocity load, the bearing tilt angle when the engine is operating at maximum speed Among them, F 角速度 F is the fulcrum load generated by the gyroscopic torque at the fulcrum under a unit angular velocity load when the engine is operating at its maximum speed. 重力 The magnitude of the load on the fulcrum under a gravitational load of 1g.

[0069] In summary, the tilt angle of the intermediate bearing under mechanical load is:

[0070]

[0071] S6. Determine the total tilt angle of the intermediate bearing under operating conditions.

[0072] Factors affecting the total tilt angle of the intermediate bearing under working conditions include: the tilt angle of the intermediate bearing caused by cold assembly of the whole machine, the tilt angle of the inner ring working surface of the intermediate bearing caused by structural deformation, the tilt angle of the outer ring working surface of the intermediate bearing caused by structural deformation, and the tilt angle of the working surface of the intermediate bearing caused by gravity or motor load.

[0073] Therefore, the total tilt angle of the intermediate bearing under working conditions is:

[0074] Stand status:

[0075] Flight status:

[0076] If the total tilt angle of the intermediate bearing obtained according to the above process can meet the anti-slip requirements, then the process ends; otherwise, return to readjust the bearing installation structure and start the analysis again.

[0077] The anti-eccentric load design method for preventing intermediate bearing slippage provided in this application comprehensively considers the influence of various key factors, which can effectively reduce the risk of intermediate bearing slippage and improve the safety and reliability of intermediate bearings.

[0078] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of designing a load biasing capacity of a slipper for preventing a slip of an intermediate bearing, characterized by, The method includes: Determine the key design factors for preventing the intermediate bearing from slipping, including the intermediate bearing tilt angle in the assembled state, the inner and outer ring tilt angles of the intermediate bearing in the working state, the intermediate bearing tilt angle under the action of gravity, and the intermediate bearing tilt angle under the action of the motor load, wherein the intermediate bearing tilt angle in the assembled state is : ； In the formula, T w is the four-point bearing outer ring runout amount, T n For four-point inner ring jump, L2 is the span of the three- or four-point bearing. L3 is the span of a four- or five-point bearing. T5 indicates the coaxiality of a five-point bearing. e is the tilt angle caused by the radial clearance of the five-point bearing; The inner ring inclination angle γ of the intermediate bearing in the working state n The outer ring inclination angle γ w Obtained by finite element analysis The tilt angle of the intermediate bearing under the action of gravity Is: ； In the formula, is the deformation difference of the intermediate bearing inner ring, To the length of the intermediate bearing inner ring, for the intermediate bearing inner ring deformation difference, L2 is the length of the intermediate bearing inner ring; The tilt angle of the intermediate bearing under the aforementioned kinematic load is: ； wherein is the fulcrum load generated by the gyroscopic moment at the fulcrum under the action of the unit angular velocity load when the engine is operating at the maximum rotational speed, The fulcrum load is the size of the load under the action of the gravity load 1g. n is the normal overload. is the inclination angle of the intermediate bearing under the action of the gravitational load; The total tilt angle of the intermediate bearing in the working state is determined. This total tilt angle includes both the working state intermediate bearing tilt angle in bench test mode and the working state intermediate bearing tilt angle in flight mode. The working state intermediate bearing tilt angle in bench test mode is: ; The total tilt angle of the intermediate bearing during flight is: ； Determine whether the total tilt angle of the intermediate bearing under working conditions meets the anti-slip requirements. If it does, the design is complete; otherwise, readjust the bearing mounting structure until the requirements are met.

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