Variable stiffness rotor support structure based on extruded squirrel cage bars and method of adjustment

Abstract

A variable stiffness rotor supporting structure based on extruded squirrel cage bars and a regulating method, belong to the field of aero-engine rotor supporting structure design, in order to solve the problem that the flexible supporting structure used in modern aero-engine is difficult to adapt to the characteristics of the variable working condition of modern aero-engine, the rotor supporting structure comprises a squirrel cage, an extrusion unit and a driving unit, the extrusion unit is sleeved on the squirrel cage, the extrusion part of the extrusion unit is embedded on the bar part in the squirrel cage, the driving part of the extrusion unit is connected with the driving end of the driving unit, and the dynamic power input end of the driving unit is connected with the external power socket through the power line. The application is mainly used as the supporting structure of the rotor in the 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 extruded 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 extruded squirrel cage bars, the rotor support structure includes a squirrel cage, an extrusion unit and a drive unit. The extrusion unit is sleeved on the squirrel cage, and the extrusion part of the extrusion unit is embedded in the cage bar part of the squirrel cage. The drive part of the extrusion unit is connected to the drive end of the drive unit, and the power input end of the drive unit is connected to an external power socket through a power line.

[0006] Furthermore, the rat cage includes a connecting flange, a fixing ring, a mounting ring, and N cage bars, where N is a positive integer. The connecting flange and the mounting ring are coaxially opposite each other. The fixing ring is fixedly connected to the end of the connecting flange near the mounting ring and is coaxial with the connecting flange. The N cage bars are equidistantly arranged between the fixing ring and the mounting ring in the circumferential direction. One end of each cage bar is fixedly connected to the fixing ring, and each cage bar is perpendicular to the end face of the fixing ring near the mounting ring. The other end of each cage bar is fixedly connected to the mounting ring.

[0007] Furthermore, the extrusion unit includes an outer ring and N extrusion blocks, where N is a positive integer. The outer ring is fitted onto the outer circular surface of the cage. The N extrusion blocks are equidistantly arranged on the inner ring wall of the outer ring along the circumference. Each extrusion block is embedded between two adjacent cage bars in the cage. The two ends of each extrusion block are respectively connected to the fixing ring and the mounting ring. The outer ring is connected to the driving end of the driving unit. The N extrusion blocks perform an extrusion action on the adjacent cage bars as the outer ring rotates.

[0008] Furthermore, N limiting slots are equidistantly machined along the circumferential direction on the inner ring wall of the outer ring, and each extrusion block is correspondingly set in a limiting slot, and the two side walls of each limiting slot in the outer ring limit one of the corresponding extrusion blocks.

[0009] Furthermore, the extrusion block includes an overlapping plate and a pressing block body. The overlapping plate is disposed on the top of the pressing block body, and both ends of the overlapping plate extend to the outside of the pressing block body. The overlapping plate is fixedly connected to the pressing block body.

[0010] Furthermore, the width of the overlapping plate is the same as the width of the main body of the pressure block;

[0011] Furthermore, the width of the pressing block body is smaller than the distance between two adjacent cage bars in the rat cage;

[0012] Furthermore, the width of the overlapping plate is the same as the width of the limiting groove in the outer ring;

[0013] Furthermore, the drive unit includes a hydraulic turntable and multiple connecting rods. The hydraulic turntable is coaxially arranged opposite to the outer ring. The multiple connecting rods are equidistantly arranged between the hydraulic turntable and the outer ring in the circumferential direction. One end of each connecting rod is fixedly connected to the end face of the outer ring near the hydraulic turntable, and each connecting rod is perpendicular to the end face of the outer ring near the hydraulic turntable. The other end of each connecting rod is fixedly connected to the rotating part of the hydraulic turntable.

[0014] A stiffness adjustment method based on a variable stiffness rotor support structure using extruded squirrel cage bars is disclosed, the method comprising the following steps:

[0015] 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:

[0016]

[0017] 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:

[0018]

[0019] 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 width of the cage bar.

[0020] The beneficial effects of this application compared to the prior art are:

[0021] This application proposes a variable stiffness rotor support structure and adjustment method based on the compression of squirrel cage bars. The stiffness of the rotor support structure can vary with the compression width of the cage bars in the squirrel cage. Under low stiffness, a hydraulic turntable, via its outer ring and transmission rod, controls the wedge block to not contact the squirrel cage bars. Under high stiffness, the hydraulic turntable controls the wedge block to contact the squirrel cage bars. By adjusting the driving force of the hydraulic turntable, the clamping force between the wedge block and the squirrel cage bars can be adjusted, thereby adjusting the stiffness of the support structure. In practical use, the aero-engine rotor initially operates with high support stiffness, i.e., the wedge block is controlled by the hydraulic turntable to press against the squirrel cage bars. When the engine rotor speed approaches the critical speed of high support stiffness, the hydraulic turntable precisely controls the wedge block to move away from the squirrel cage bars, reducing the support stiffness and thus lowering the critical speed. This keeps the operating speed away from the critical speed, achieving the effect of reducing resonance peaks. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the variable stiffness rotor support structure described in this application;

[0023] Figure 2 This is a schematic diagram of the variable stiffness rotor support structure described in this application under a relatively low stiffness state;

[0024] Figure 3 This is a schematic diagram of the variable stiffness rotor support structure described in this application under a large stiffness state;

[0025] Figure 4 This is a schematic diagram of the extrusion block in the variable stiffness rotor support structure described in this application;

[0026] Figure 5 This is a schematic diagram of the squirrel cage in the variable stiffness rotor support structure described in this application;

[0027] Figure 6This is a schematic diagram of the fit between the hydraulic turntable, connecting rod, outer ring and extrusion block in the variable stiffness rotor support structure described in this application.

[0028] Figure 7 This is a schematic diagram of the fit between the squirrel cage and the compression block in the variable stiffness rotor support structure described in this application.

[0029] The diagram shows: 1. Rat cage, 11. Connecting flange, 12. Fixing ring, 13. Mounting ring, 14. Cage bar, 2. Extrusion block, 21. Overlap plate, 22. Press block body, 3. Hydraulic turntable, 4. Connecting rod, and 5. Outer ring. Detailed Implementation

[0030] Specific implementation method one: Combining Figures 1 to 7 This embodiment describes a variable stiffness rotor support structure based on extruded squirrel cage bars. The rotor support structure includes a squirrel cage 1, an extrusion unit, and a drive unit. The extrusion unit is sleeved on the squirrel cage 1, and the extrusion part of the extrusion unit is embedded in the cage bar part of the squirrel cage 1. The drive part of the extrusion unit is connected to the drive end of the drive unit, and the power input end of the drive unit is connected to an external power socket through a power cord.

[0031] This application provides an active control variable stiffness support structure for aero-engine rotors based on hydraulically driven wedge blocks pressing squirrel cage bars. The variable stiffness support structure, under the premise of simple structure, can achieve precise and rapid stiffness adjustment, thereby realizing active control of aero-engine rotors. Compared with traditional squirrel cage flexible support structures, it can suppress rotor vibration response over a wider speed range and under more operating conditions.

[0032] Specific Implementation Method Two: Combining Figures 1 to 7 This embodiment differs from specific embodiment one in that the cage 1 includes a connecting flange 11, a fixing ring 12, a mounting ring 13, and N cage bars 14, where N is a positive integer. The connecting flange 11 and the mounting ring 13 are coaxially opposite each other. The fixing ring 12 is fixedly connected to the end of the connecting flange 11 near the mounting ring 13, and the fixing ring 12 is coaxial with the connecting flange 11. The N cage bars 14 are equidistantly arranged circumferentially between the fixing ring 12 and the mounting ring 13. One end of each cage bar 14 is fixedly connected to the fixing ring 12, and the end face of each cage bar 14 near the mounting ring 13 is perpendicular to the fixed ring 12. The other end of each cage bar 14 is fixedly connected to the mounting ring 13. Other components and connection methods are the same as in specific embodiment one.

[0033] Specific implementation method three: Combining Figures 1 to 7This embodiment differs from Specific Embodiment Two in that the extrusion unit includes an outer ring 5 and N extrusion blocks 2, where N is a positive integer. The outer ring 5 is fitted onto the outer circumferential surface of the cage 1. The N extrusion blocks 2 are equidistantly arranged on the inner ring wall of the outer ring 5, and each extrusion block 2 is embedded between two adjacent cage bars 14 in the cage 1. The two ends of each extrusion block 2 overlap the fixing ring 12 and the mounting ring 13, respectively. The outer ring 5 is connected to the driving end of the driving unit. The N extrusion blocks 2, as the outer ring 5 rotates, extrude an extrusion action on the adjacent cage bars 14. Other components and connections are the same as in Specific Embodiment Two.

[0034] Specific implementation method four: Combination Figures 1 to 7 This embodiment differs from specific embodiment three in that N circumferentially spaced limiting slots are machined on the inner ring wall of the outer ring 5. Each extrusion block 2 is correspondingly disposed in one limiting slot, and the two side walls of each limiting slot in the outer ring 5 limit the movement of a corresponding extrusion block 2. Other components and connection methods are the same as in specific embodiment three.

[0035] Specific Implementation Method Five: Combining Figures 1 to 7 This embodiment differs from specific embodiment four in that the extrusion block 2 includes an overlapping plate 21 and a pressing block body 22. The overlapping plate 21 is disposed on the top of the pressing block body 22, and both ends of the overlapping plate 21 extend to the outside of the pressing block body 22. The overlapping plate 21 is fixedly connected to the pressing block body 22. Other components and connection methods are the same as in specific embodiment four.

[0036] Referring to the descriptions of specific embodiments two to five, the stiffness of the variable stiffness support structure described in this application is provided jointly by the squirrel cage and the compression block. Figure 2 Under the low stiffness condition shown, the extrusion block does not contact the cage bars, and the stiffness of the supporting structure is mainly provided by the cage; Figure 3 Under the premise of high rigidity shown, the extrusion block is controlled to extrude the cage bars of the squirrel cage. The rigidity of the supporting structure is provided by the squirrel cage and the extrusion block together, and the specific rigidity can be adjusted according to the degree of compression between the extrusion block and the cage bars of the squirrel cage.

[0037] Specific Implementation Method Six: Combination Figures 1 to 7 This embodiment differs from Specific Embodiment Five in that the width of the overlapping plate 21 is the same as the width of the pressure block body 22. Other components and connection methods are the same as in Specific Embodiment Five.

[0038] Specific implementation method seven: Combination Figures 1 to 7This embodiment differs from specific embodiment five in that the width of the pressing block body 22 is smaller than the distance between two adjacent cage bars in the mouse cage 1. Other components and connection methods are the same as in specific embodiment five.

[0039] Specific implementation method eight: Combination Figures 1 to 7 This embodiment differs from specific embodiment five in that the width of the overlapping plate 21 is the same as the width of the limiting groove in the outer ring 5. Other components and connection methods are the same as in specific embodiment five.

[0040] Specific Implementation Method Nine: Combining Figures 1 to 7 This embodiment differs from specific embodiment five in that the driving unit includes a hydraulic turntable 3 and multiple connecting rods 4. The hydraulic turntable 3 is coaxially opposite to the outer ring 5. The multiple connecting rods 4 are equidistantly arranged circumferentially between the hydraulic turntable 3 and the outer ring 5. One end of each connecting rod 4 is fixedly connected to the end face of the outer ring 5 near the hydraulic turntable 3, and each connecting rod 4 is perpendicular to the end face of the outer ring 5 near the hydraulic turntable 3. The other end of each connecting rod 4 is fixedly connected to the rotating part of the hydraulic turntable 3. Other components and connection methods are the same as in specific embodiment five.

[0041] The hydraulic turntable 3 used in this embodiment is a SE series hydraulic turntable produced by Jining Feiang Hydraulic Machinery Co., Ltd., and its specific model is selected according to the size of the squirrel cage 1.

[0042] Specific Implementation Method Ten: Combining Figures 1 to 7 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:

[0043] 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:

[0044]

[0045] 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:

[0046]

[0047] 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 width of the cage bar.

[0048] In this embodiment, before adjusting the stiffness of the squirrel cage, it is necessary to determine the specific structure of the extrusion block 2 based on the structural parameters of the squirrel cage. The number of extrusion blocks 2 is the same as the number of gaps between the squirrel cage bars. The outer ring structure is designed based on the specific structure of the extrusion block 2. The outer ring 5 has a limiting groove that cooperates with the extrusion block 3. The hydraulic turntable 3 with appropriate power is selected based on the specific structural parameters of the squirrel cage 1 and the extrusion block 2.

[0049] When the aero-engine rotor is initially running, the hydraulic turntable 3 controls the pressing block 2 to press the squirrel cage bars 14 through the outer ring 5, such as... Figure 3 As shown, the supporting structure has high stiffness at this time; when the rotor speed of the aero-engine approaches the critical speed under high stiffness, the hydraulic turntable 3 controls the extrusion block 2 to move away from the squirrel cage bars through the outer ring 5, as shown. Figure 2 As shown, at this time, the compression block 2 contributes very little to the stiffness of the support structure, and the stiffness of the support structure is at a small stiffness, which is equal to the stiffness of the squirrel cage 1 itself. At this time, the critical speed of the engine rotor becomes smaller, thus offsetting the speed of the engine rotor, which has the effect of reducing the vibration peak.

[0050] The control logic of the variable stiffness support structure is as follows: when the rotor starts, the hydraulic turntable controls the outer ring to drive the extrusion block 2 to press the squirrel cage structure; when the speed sensor detects that the rotor speed is close to the critical speed of the rotor under high stiffness, the PLC control system controls the hydraulic turntable 3 to drive the outer ring 5 and then controls the extrusion block 2 to move away from the squirrel cage bars 14, thereby reducing the stiffness of the squirrel cage support structure and the corresponding critical speed, so that the working speed is far away from the critical speed, thereby suppressing the rotor vibration response.

[0051] 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 extruded squirrel cage bars, characterized in that: The rotor support structure includes a squirrel cage (1), an extrusion unit and a drive unit. The extrusion unit is sleeved on the squirrel cage (1), and the extrusion part of the extrusion unit is embedded in the cage bar part of the squirrel cage (1). The drive part of the extrusion unit is connected to the drive end of the drive unit, and the power input end of the drive unit is connected to an external power socket through a power line. The rat cage (1) includes a connecting flange (11), a fixing ring (12), a mounting ring (13), and N cage bars (14), where N is a positive integer; The extrusion unit includes an outer ring (5) and N extrusion blocks (2), where N is a positive integer. The outer ring (5) is fitted onto the outer circular surface of the rat cage (1). The N extrusion blocks (2) are equidistantly arranged on the inner ring wall of the outer ring (5) along the circumference. Each extrusion block (2) is embedded between two adjacent cage bars (14) in the rat cage (1). The two ends of each extrusion block (2) are respectively connected to the fixing ring (12) and the mounting ring (13). The outer ring (5) is connected to the driving end of the driving unit. The N extrusion blocks (2) perform extrusion action on the adjacent cage bars (14) as the outer ring (5) rotates.

2. The variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 1, characterized in that: The connecting flange (11) and the mounting ring (13) are coaxially opposite each other. The fixing ring (12) is fixedly connected to the end of the connecting flange (11) near the mounting ring (13), and the fixing ring (12) and the connecting flange (11) are coaxially connected. N cage bars (14) are equidistantly arranged between the fixing ring (12) and the mounting ring (13) in the circumferential direction. One end of each cage bar (14) is fixedly connected to the fixing ring (12), and the end face of each cage bar (14) near the mounting ring (13) of the fixing ring (12) is perpendicular to it. The other end of each cage bar (14) is fixedly connected to the mounting ring (13).

3. The variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 2, characterized in that: The inner ring wall of the outer ring (5) is equidistantly machined with N limiting slots along the circumference. Each extrusion block (2) is set in a corresponding limiting slot, and the two side walls of each limiting slot in the outer ring (5) are limited by a corresponding extrusion block (2).

4. The variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 3, characterized in that: The extrusion block (2) includes an overlap plate (21) and a block body (22). The overlap plate (21) is located on the top of the block body (22), and both ends of the overlap plate (21) extend to the outside of the block body (22). The overlap plate (21) is fixedly connected to the block body (22).

5. A variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 4, characterized in that: The width of the overlapping plate (21) is the same as the width of the pressing block body (22).

6. A variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 5, characterized in that: The width of the main body (22) of the pressing block is smaller than the distance between two adjacent cage bars in the rat cage (1).

7. A variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 6, characterized in that: The width of the overlapping plate (21) is the same as the width of the limiting slot in the outer ring (5).

8. A variable stiffness rotor support structure based on extruded squirrel cage bars according to claim 7, characterized in that: The drive unit includes a hydraulic turntable (3) and multiple connecting rods (4). The hydraulic turntable (3) and the outer ring (5) are coaxially opposite each other. The multiple connecting rods (4) are equidistantly arranged between the hydraulic turntable (3) and the outer ring (5) along the circumference. One end of each connecting rod (4) is fixedly connected to the end face of the outer ring (5) near the hydraulic turntable (3), and each connecting rod (4) is perpendicular to the end face of the outer ring (5) near the hydraulic turntable (3). The other end of each connecting rod (4) is fixedly connected to the rotating part of the hydraulic turntable (3).

9. A method for stiffness adjustment using a variable stiffness rotor support structure based on extruded squirrel cage bars as described in any one of claims 1 to 8, 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 width of the cage bar.

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