Variable stiffness rotor support structure based on adjusting length of squirrel cage bars and adjusting method

Abstract

The application discloses a variable stiffness rotor supporting structure based on adjusting the length of a squirrel cage bar and an adjusting method, belongs to the field of rotor supporting structure design of an aero-engine, and aims at solving the problem that the flexible supporting structure adopted by a modern aero-engine is difficult to adapt to the characteristics of the changeable working conditions of the modern aero-engine. The application comprises a mounting seat, a fixed squirrel cage, a movable squirrel cage, a sliding seat and two sliding units. The fixed squirrel cage is arranged at the center of the front side of the mounting seat, the movable squirrel cage is inserted into the other end of the fixed squirrel cage, one end of the movable squirrel cage is in sliding connection with the other end of the fixed squirrel cage, the other end of the movable squirrel cage is sleeved with the sliding seat, and the two sliding units are arranged on the back side of the mounting seat. The fixed end of each sliding unit is fixedly connected with the back side of the mounting seat, and the sliding end of each sliding unit penetrates through the mounting seat and is detachably connected with the sliding seat. The application is mainly used as a supporting structure of a rotor in an aero-engine.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine rotor support structure design, specifically relating to a variable stiffness rotor support structure and adjustment method based on adjusting the length of the squirrel cage bars. Background Technology

[0002] As the core power source for aircraft flight, the aero-engine is a highly complex and precise thermodynamic rotary machine. Modern aero-engines are generally developed towards lighter weight, higher thrust-to-weight ratio, higher speed, and greater safety and reliability. Statistics show that vibration-induced failures account for 50% to 60% of all aero-engine failures. The rotor system is a core component of the aero-engine, acting as both the main source and primary excitation of engine vibration. Therefore, studying the dynamic characteristics of the aero-engine rotor system is of great significance for mitigating aero-engine vibration and improving its service life and reliability.

[0003] Modern aero engines mostly adopt flexible support structures. Traditional flexible support structures have fixed stiffness, which makes it difficult to adapt to the changing operating conditions of modern aero engines. Therefore, developing a variable stiffness rotor support structure that can actively control the support stiffness under different operating conditions during the operation of modern aero engines, thereby moving away from the critical speed and reducing resonance peak value, is very much in line with practical needs. Summary of the Invention

[0004] In order to solve the problem that the flexible support structure used in modern aero engines is difficult to adapt to the changing operating conditions of modern aero engines, this invention provides a variable stiffness rotor support structure and adjustment method based on adjusting the length of the squirrel cage bars.

[0005] A variable stiffness rotor support structure based on adjusting the length of the cage bars of a squirrel cage includes a mounting base, a fixed squirrel cage, a movable squirrel cage, a sliding seat, and two sliding units. The fixed squirrel cage is located at the center of the front side of the mounting base, and one end of the fixed squirrel cage is detachably connected to the mounting base. The movable squirrel cage is inserted into the other end of the fixed squirrel cage, and one end of the movable squirrel cage is slidably connected to the other end of the fixed squirrel cage. The movable squirrel cage and the fixed squirrel cage are coaxially arranged. A sliding seat is fitted on the other end of the movable squirrel cage, and the sliding seat is fixedly connected to the other end of the movable squirrel cage. The two sliding units are located on the back side of the mounting base and are symmetrically arranged along the longitudinal plane containing the axis of the fixed squirrel cage. The fixed end of each sliding unit is fixedly connected to the back side of the mounting base, and the sliding end of each sliding unit passes through the mounting base and is detachably connected to the sliding seat.

[0006] Furthermore, the fixed cage includes a connecting flange, a cage bar ring frame, and a mounting ring. The cage bar ring frame includes a fixing ring and N fixing cage bars, where N is a positive integer. The connecting flange is fixedly disposed at the center of the front side of the mounting base and is detachably connected to the mounting base by bolts. The fixing ring is fixedly connected to the end of the connecting flange away from the mounting base and is coaxial with the connecting flange. The N fixing cage bars are equidistantly arranged circumferentially on the end face of the fixing ring away from the connecting flange, and one end of each fixing cage bar is fixedly connected to the fixing ring. Each fixing cage bar is perpendicular to the end face of the fixing ring away from the connecting flange. The mounting ring is disposed on the other end of the N fixing cage bars and is coaxial with the connecting flange. The other end of each fixing cage bar is fixedly connected to the outer circular surface of the mounting ring.

[0007] Furthermore, the mounting ring has multiple threaded holes machined circumferentially at equal intervals on the end face away from the connecting flange.

[0008] Furthermore, the movable cage includes a movable ring and N movable cage bars. The movable ring is disposed on the sliding seat near the mounting end, and the sliding seat is fixedly connected to the movable ring. The N movable cage bars are equidistantly arranged on the end face of the movable ring near the connecting flange along the circumference. One end of each movable cage bar is fixedly connected to the movable ring, and each movable cage bar is perpendicular to the end face of the movable ring away from the connecting flange. The other end of each movable cage bar is disposed between two adjacent fixed cage bars, and the other end of each movable cage bar is slidably connected to the outer circular wall of the mounting ring.

[0009] Furthermore, the sliding seat is a circular sliding seat, and two connecting ears are provided at equal intervals along the circumference on the outer circular wall of the circular sliding seat. Each connecting ear is integrally formed with the sliding seat. A through hole is machined at the center of the front side of each connecting ear, and four mounting threaded holes are machined at equal intervals along the circumference of the through hole on the front side of each connecting ear.

[0010] Furthermore, the sliding unit includes a rotary motor and a sliding nut. The rotary motor is disposed on the back side of the mounting base, and the housing of the rotary motor is detachably connected to the mounting base by bolts. The power output shaft of the rotary motor passes through the mounting base and is disposed on the front side of the mounting base. A threaded section is machined on the outer circular surface of the power output shaft in the rotary motor. The sliding nut is sleeved on the threaded section and is threadedly connected to the power output shaft of the rotary motor. A connecting lug on the sliding base is sleeved on the power output shaft in the rotary motor through a through hole. Each connecting lug is correspondingly disposed between a sliding nut and the mounting base, and each sliding nut is detachably connected to the corresponding connecting lug by bolts.

[0011] A stiffness adjustment method based on a variable stiffness rotor support structure that adjusts the length of the squirrel cage bars, the method being implemented through the following steps:

[0012] The squirrel cage stiffness is designed based on the engine's commonly used operating speed. The dynamic equation of the rotor-variable stiffness support structure system is as follows:

[0013]

[0014] In the above formula, M represents the mass matrix of the controlled rotor structure, C represents the damping matrix of the controlled rotor structure, G represents the gyroscopic torque matrix of the controlled rotor structure, K represents the stiffness matrix of the controlled rotor structure, F(t) is the rotor unbalance excitation force, and x(t) represents the displacement response matrix. Represents the velocity response matrix. Represents the acceleration response matrix, and the squirrel cage stiffness K. 鼠笼 The variable stiffness part of K in equation (1) is the variable stiffness part, while the remaining stiffness in K is the invariant stiffness. The stiffness of the squirrel cage is K. 鼠笼 The empirical formula is:

[0015]

[0016] In the above formula, L is the length of the cage bar, n is the number of cage bars, E is the Young's modulus of the cage material, b is the width of the cage bar, and h is the thickness of the cage bar. As can be seen from formula (2), the stiffness of the cage can be changed by changing the effective length of the cage bar.

[0017] The beneficial effects of this application compared to the prior art are:

[0018] This application proposes a variable stiffness rotor support structure and adjustment method based on adjusting the length of the squirrel cage bars. This allows the stiffness of the rotor support structure to change with the axial position of the moving squirrel cage. As the moving squirrel cage moves closer to the fixed squirrel cage, the effective length of the variable stiffness support structure decreases, and the stiffness gradually increases. Conversely, as the moving squirrel cage moves further away from the fixed squirrel cage, the effective length of the variable stiffness support structure increases, and the stiffness gradually decreases. This adjustment method is highly flexible, simple, reliable, and easy to maintain and repair, making it suitable for use in aero-engines. Furthermore, in actual use, the aero-engine rotor initially operates with high support stiffness, meaning the axial distance between the moving and fixed squirrel cages is small. When the engine rotor speed approaches the critical speed for high support stiffness, a linear screw motor precisely controls the moving squirrel cage to move away from the fixed squirrel cage, reducing the support stiffness and thus lowering the critical speed. This allows the operating speed to move away from the critical speed, achieving the effect of reducing resonance peaks. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the variable stiffness rotor support structure described in this application under a relatively low stiffness state;

[0020] Figure 2This is a schematic diagram of the variable stiffness rotor support structure described in this application under a large stiffness state;

[0021] Figure 3 This is a schematic diagram of the fixed squirrel cage in the variable stiffness rotor support structure described in this application;

[0022] Figure 4 This is a schematic diagram of the movable squirrel cage in the variable stiffness rotor support structure described in this application;

[0023] Figure 5 This is a structural diagram of the linear lead screw motor in the variable stiffness rotor support structure described in this application;

[0024] Figure 6 This is a diagram showing the screw and nut relationships in the linear screw motor, fixed squirrel cage, and movable squirrel cage of the variable stiffness rotor support structure described in this application.

[0025] In the figure, 1 is the mounting base, 2 is the fixed cage, 21 is the connecting flange, 22 is the cage bar ring frame, 23 is the mounting ring, 3 is the movable cage, 31 is the movable cage bar, 32 is the movable ring, 4 is the sliding seat, 41 is the through hole, 42 is the mounting threaded hole, 5 is the threaded section, 6 is the rotating motor, and 7 is the sliding nut. Detailed Implementation

[0026] Specific implementation method one: Combining Figures 1 to 6 This embodiment describes a variable stiffness rotor support structure based on adjusting the length of the cage bars of a squirrel cage. The support structure includes a mounting base 1, a fixed squirrel cage 2, a movable squirrel cage 3, a sliding seat 4, and two sliding units. The fixed squirrel cage 2 is located at the center of the front side of the mounting base 1, and one end of the fixed squirrel cage 2 is detachably connected to the mounting base 1. The movable squirrel cage 3 is inserted into the other end of the fixed squirrel cage 2, and one end of the movable squirrel cage 3 is slidably connected to the other end of the fixed squirrel cage 2. The movable squirrel cage 3 and the fixed squirrel cage 2 are coaxially arranged. The sliding seat 4 is sleeved on the other end of the movable squirrel cage 3, and the sliding seat 4 is fixedly connected to the other end of the movable squirrel cage 3. The two sliding units are located on the back side of the mounting base 1, and the two sliding units are symmetrically arranged along the longitudinal plane containing the axis of the fixed squirrel cage 2. The fixed end of each sliding unit is fixedly connected to the back side of the mounting base 1, and the sliding end of each sliding unit passes through the mounting base 1 and is detachably connected to the sliding seat 4.

[0027] This application provides a variable stiffness rotor support structure based on adjusting the length of the squirrel cage bars. Under the premise of simple and reliable structure, the variable stiffness support structure can achieve precise stiffness control, thereby realizing active control of the aero-engine rotor. Compared with the traditional squirrel cage flexible support structure, it can suppress rotor vibration response in a wider speed range and more operating conditions.

[0028] Specific Implementation Method Two: Combining Figures 1 to 6This embodiment differs from specific embodiment one in that the fixed cage 2 includes a connecting flange 21, a cage bar ring frame 22, and a mounting ring 23. The cage bar ring frame 22 includes a fixing ring and N fixing cage bars, where N is a positive integer. The connecting flange 21 is fixedly disposed at the center of the front side of the mounting base 1 and is detachably connected to the mounting base 1 by bolts. The fixing ring is fixedly connected to the end of the connecting flange 21 away from the mounting base 1 and is coaxial with the connecting flange 21. The N fixing cage bars are equidistantly arranged circumferentially on the end face of the fixing ring away from the connecting flange 21, and one end of each fixing cage bar is fixedly connected to the fixing ring. Each fixing cage bar is perpendicular to the end face of the fixing ring away from the connecting flange 21. The mounting ring 23 is disposed on the other end of the N fixing cage bars and is coaxial with the connecting flange 21. The other end of each fixing cage bar is fixedly connected to the outer circular surface of the mounting ring 23. Other components and connection methods are the same as in specific embodiment one.

[0029] Specific implementation method three: Combining Figures 1 to 6 This embodiment differs from Specific Embodiment Two in that the mounting ring 23 has multiple threaded holes 24 machined circumferentially at equal intervals on its end face away from the connecting flange 21. Other components and connection methods are the same as in Specific Embodiment Two.

[0030] Specific implementation method four: Combination Figures 1 to 6 This embodiment differs from Specific Embodiment Three in that the movable cage 3 includes a movable ring 32 and N movable cage bars 31. The movable ring 32 is disposed on the end of the sliding seat 4 near the mounting seat 1, and the sliding seat 4 is fixedly connected to the movable ring 32. The N movable cage bars 31 are equidistantly arranged circumferentially on the end face of the movable ring 32 near the connecting flange 21. One end of each movable cage bar 31 is fixedly connected to the movable ring 32, and each movable cage bar 31 is perpendicular to the end face of the movable ring 32 away from the connecting flange 21. The other end of each movable cage bar 31 is disposed between two adjacent fixed cage bars, and the other end of each movable cage bar 31 is slidably connected to the outer circular wall of the mounting ring 23. Other components and connection methods are the same as in Specific Embodiment Three.

[0031] Referring to the descriptions of specific embodiments two to four, the threaded hole on the end of the mounting ring 23 away from the connecting flange 21 is used to install the engine rotor. The structural dimensions of the movable cage bar 31 between the fixed cage 2 and the movable cage 3 are the same as those of the fixed cage bar, which facilitates the structural stability between the fixed cage 2 and the movable cage 3. Furthermore, the number of movable cage bars 31 is the same as the number of fixed cage bars, ensuring that the fixed cage 2 and the movable cage 3 are staggered.

[0032] Specific Implementation Method Five: Combining Figures 1 to 6This embodiment differs from specific embodiment four in that the sliding seat 4 is a circular sliding seat. Two connecting ears are equidistantly spaced along the circumference of the outer circular wall of the circular sliding seat. Each connecting ear is integrally formed with the sliding seat 4. A through hole 41 is machined at the center of the front side of each connecting ear, and four mounting threaded holes 42 are equidistantly machined along the circumference of the through hole 41 on the front side of each connecting ear. Other components and connection methods are the same as in specific embodiment four.

[0033] Specific Implementation Method Six: Combination Figures 1 to 6 This embodiment differs from specific embodiment five in that the sliding unit includes a rotary motor 6 and a sliding nut 7. The rotary motor 6 is located on the back side of the mounting base 1, and its housing is detachably connected to the mounting base 1 via bolts. The power output shaft of the rotary motor 6 passes through the mounting base 1 and is located on its front side. A threaded section 5 is machined on the outer circumference of the power output shaft of the rotary motor 6. The sliding nut 7 is fitted onto the threaded section 5 and is threadedly connected to the power output shaft of the rotary motor 6. A connecting lug on the sliding seat 4 is fitted onto the power output shaft of the rotary motor 6 through a through hole 41. Each connecting lug is correspondingly located between a sliding nut 7 and the mounting base 1, and each sliding nut 7 is detachably connected to its corresponding connecting lug via bolts. Other components and connection methods are the same as in specific embodiment five.

[0034] As explained in Specific Embodiments 5 and 6, the sliding unit, as an important component for adjusting the sliding of the movable squirrel cage 3, adopts a screw and nut mechanism as the main power transmission method. The rotating motor 6 drives the threaded section 5 to rotate. As the threaded section 5 rotates, the sliding nut 7 can reciprocate along the length extension direction of the threaded section 5. The double sliding unit and the sliding seat 4 jointly drive the movable squirrel cage 3 to reciprocate. The double sliding unit acts as a guide rail to ensure the accuracy of the movable squirrel cage 3 during movement and avoid the movable squirrel cage 3 from tilting due to unilateral force during sliding, which would affect the working stability of the squirrel cage structure.

[0035] Specific implementation method seven: Combining Figures 1 to 6 This embodiment describes an adjustment method for a variable stiffness rotor support structure based on adjusting the length of the squirrel cage bars. The adjustment method is achieved through the following steps:

[0036] The squirrel cage stiffness is designed based on the engine's commonly used operating speed. The dynamic equation of the rotor-variable stiffness support structure system is as follows:

[0037]

[0038] In the above formula, M represents the mass matrix of the controlled rotor structure, C represents the damping matrix of the controlled rotor structure, G represents the gyroscopic torque matrix of the controlled rotor structure, K represents the stiffness matrix of the controlled rotor structure, F(t) is the rotor unbalance excitation force, and x(t) represents the displacement response matrix. Represents the velocity response matrix. Represents the acceleration response matrix, and the squirrel cage stiffness K. 鼠笼 The variable stiffness part of K in equation (1) is the variable stiffness part, while the remaining stiffness in K is the invariant stiffness. The stiffness of the squirrel cage is K. 鼠笼 The empirical formula is:

[0039]

[0040] In the above formula, L is the length of the cage bar, n is the number of cage bars, E is the Young's modulus of the cage material, b is the width of the cage bar, and h is the thickness of the cage bar. As can be seen from formula (2), the stiffness of the cage can be changed by changing the effective length of the cage bar.

[0041] The present invention has been disclosed above with preferred embodiments, but it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the present invention. However, any simple 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 present invention shall still fall within the scope of the present invention.

Claims

1. A variable stiffness rotor support structure based on adjusting the length of the squirrel cage bars, characterized in that: The support structure includes a mounting base (1), a fixed cage (2), a movable cage (3), a sliding seat (4), and two sliding units. The fixed cage (2) is located at the center of the front side of the mounting base (1), and one end of the fixed cage (2) is detachably connected to the mounting base (1). The movable cage (3) is inserted on the other end of the fixed cage (2), and one end of the movable cage (3) is slidably connected to the other end of the fixed cage (2). The movable cage (3) is coaxially arranged with the fixed cage (2). The other end of the movable cage (3) is fitted with a sliding seat (4), and the sliding seat (4) is fixedly connected to the other end of the movable cage (3). The two sliding units are located on the back side of the mounting base (1), and the two sliding units are symmetrically arranged along the longitudinal plane where the axis of the fixed cage (2) is located. The fixed end of each sliding unit is fixedly connected to the back side of the mounting base (1), and the sliding end of each sliding unit passes through the mounting base (1) and is detachably connected to the sliding seat (4). The fixed rat cage (2) includes a connecting flange (21), a cage bar ring frame (22), and a mounting ring (23). The cage bar ring frame (22) includes a fixing ring and N fixing cage bars, where N is a positive integer. The connecting flange (21) is fixedly installed at the center of the front side of the mounting base (1), and the connecting flange (21) is detachably connected to the mounting base (1) by bolts. The fixing ring is fixedly connected to the end of the connecting flange (21) away from the mounting base (1), and the fixing ring is connected to the connecting flange (23). 1) Coaxial arrangement, N fixed cage bars are equidistantly arranged on the end face of the fixed ring away from the connecting flange (21) along the circumference, and one end of each fixed cage bar is fixedly connected to the fixed ring. Each fixed cage bar is perpendicular to the end face of the fixed ring away from the connecting flange (21). The mounting ring (23) is set on the other end of the N fixed cage bars, and the mounting ring (23) is coaxially arranged with the connecting flange (21). The other end of each fixed cage bar is fixedly connected to the outer circle surface of the mounting ring (23). The mounting ring (23) has multiple threaded holes (24) machined circumferentially at equal intervals on the end face away from the connecting flange (21). The movable cage (3) includes a movable ring (32) and N movable cage bars (31). The movable ring (32) is disposed on the end of the sliding seat (4) near the mounting seat (1), and the sliding seat (4) is fixedly connected to the movable ring (32). The N movable cage bars (31) are arranged equidistantly along the circumference on the end face of the movable ring (32) near the connecting flange (21). One end of each movable cage bar (31) is fixedly connected to the movable ring (32). Each movable cage bar (31) is perpendicular to the end face of the movable ring (32) away from the connecting flange (21). The other end of each movable cage bar (31) is disposed between two adjacent fixed cage bars, and the other end of each movable cage bar (31) is slidably connected to the outer circular wall of the mounting ring (23).

2. The variable stiffness rotor support structure based on adjusting the length of the squirrel cage bars according to claim 1, characterized in that: The sliding seat (4) is a circular sliding seat. Two connecting ears are provided at equal intervals along the circumference on the outer circular wall of the circular sliding seat. Each connecting ear is integrally formed with the sliding seat (4). A through hole (41) is machined at the center of the front side of each connecting ear. Four mounting threaded holes (42) are machined at equal intervals along the circumference of the through hole (41) on the front side of each connecting ear.

3. The variable stiffness rotor support structure based on adjusting the length of the squirrel cage bars according to claim 2, characterized in that: The sliding unit includes a rotating motor (6) and a sliding nut (7). The rotating motor (6) is located on the back side of the mounting base (1), and the housing of the rotating motor (6) is detachably connected to the mounting base (1) by bolts. The power output shaft of the rotating motor (6) passes through the mounting base (1) and is located on the front side of the mounting base (1). A threaded section (5) is machined on the outer circular surface of the power output shaft in the rotating motor (6). The sliding nut (7) is sleeved on the threaded section (5), and the sliding nut (7) is threadedly connected to the power output shaft of the rotating motor (6). A connecting lug on the sliding seat (4) is sleeved on the power output shaft in the rotating motor (6) through a through hole (41), and each connecting lug is correspondingly located between a sliding nut (7) and the mounting base (1), and each sliding nut (7) is detachably connected to the corresponding connecting lug by bolts.

4. A stiffness adjustment method using the variable stiffness rotor support structure based on adjusting the length of the squirrel cage bars as described in any one of claims 1 to 3, characterized in that: The adjustment method is achieved through the following steps: The squirrel cage stiffness is designed based on the engine's commonly used operating speed. The dynamic equation of the rotor-variable stiffness support structure system is as follows: （1） In the above formula, M represents the mass matrix of the controlled rotor structure, C represents the damping matrix of the controlled rotor structure, G represents the gyroscopic torque matrix of the controlled rotor structure, K represents the stiffness matrix of the controlled rotor structure, and F(t) is the rotor unbalance excitation force. Represents the displacement response matrix. Represents the velocity response matrix. Represents the acceleration response matrix and the squirrel cage stiffness. The variable stiffness part of K in equation (1) is the stiffness of the cage, while the remaining stiffnesses in K are invariable. The empirical formula is: （2） In the above formula, L is the length of the cage bar, n is the number of cage bars, E is the Young's modulus of the cage material, b is the width of the cage bar, and h is the thickness of the cage bar. As can be seen from formula (2), the stiffness of the cage can be changed by changing the effective length of the cage bar.

Images