A test device for simulating the structure of a non-centering squeeze film damper

Abstract

The application discloses a test device for simulating the structure of a non-centering extrusion oil film damper, which comprises a mandrel, a positioning force transmission rod, a spring rotating component, a pulling cylinder, an intermediate top cylinder, a stop ring, a spring ring, a bushing and the like. By adjusting the height of the intermediate top cylinder, the pulling force of the spring rotating component on the mandrel is changed, the dynamic eccentricity ratio of the extrusion oil film damper under different rotating speeds is simulated, and the constant axial pre-tightening force is applied to the non-centering extrusion oil film damper by the stop ring, the spring ring and the bushing, so that the axial positioning purpose is achieved. The device has a simple structure and can solve the dynamic test problem of the non-centering extrusion oil film damper caused by the rotor gravity and the initial axial pre-tightening force.

Description

Technical Field

[0001] This invention relates to the field of rotor vibration reduction structure dynamic characteristic testing, and in particular to a rotor dynamic characteristic testing device that simulates a non-centering squeeze oil film damper. Background Technology

[0002] Squeeze film dampers (SFDs) are crucial vibration-damping components in rotor-support systems, widely used in aero-engines, UAV power supply systems, and other applications. SFDs are typically centering structures, with the inner ring being the outer ring of the bearing, while the outer ring is fixed to the bearing housing or squirrel cage spring support, centered and positioned by the support structure. In recent years, in the design of small rotor-support systems such as aero-engine auxiliary power units, due to limitations in overall weight and structural dimensions, a non-centering structure is needed to replace the traditional concentric squeeze film damper structure, thereby achieving vibration reduction during high-speed rotor operation within limited space. However, the vibration reduction mechanism of non-centering squeeze film dampers is not yet fully understood. Their vibration reduction effect is highly dependent not only on rotor speed but also on the oil film gap, oil film width, oil supply temperature, oil supply pressure, dynamic eccentricity, and static eccentricity of the squeeze film damper itself. Therefore, before applying them to engine and other complete machine structures, it is necessary to design experimental devices to simulate this non-centering structure and understand its dynamic characteristics.

[0003] Compared to a centering structure, the direct impact of a non-centering structure on the rotor system is that the influence of gravity on the dynamic characteristics of the SFD (Spindle-Free Damping) cannot be ignored. At zero speed, due to the non-centering support, the rotor's weight falls entirely on the outer ring of the SFD, resulting in a static eccentricity of 100%. At non-zero speeds, the support stiffness of the SFD continuously changes non-linearly with the rotational speed, and the static eccentricity caused by gravity also continuously changes non-linearly. The non-linear factors affecting the overall support stiffness and damping are now influenced by gravity.

[0004] Therefore, the design challenge of non-centering SFD test equipment lies in how to apply rotor gravity to the SFD under variable speed loads. This problem involves the specific test equipment, namely, how to design a gravity-related test structure based on a bidirectional excitation tester for SFD dynamic characteristics. Furthermore, non-centering SFDs generally have a constant preload or initial axial position, so the structural design of its preload is also crucial. Summary of the Invention

[0005] This invention designs a test device for simulating the dynamic characteristics of a non-centering SFD structure, and solves the structural problems of applying rotor gravity and axial preload in the design of the test device.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A test apparatus for simulating the structure of a non-centering extrusion oil film damper includes a mandrel, several force forks, two load-bearing components, and an extrusion oil film damper.

[0008] Two identical load-bearing components are respectively supported at the front and rear ends of the mandrel. Each load-bearing component includes a positioning force transmission rod, a central top cylinder, compression springs symmetrically arranged on both sides of the positioning force transmission rod, and two side pull cylinders supporting the compression springs. The central top cylinder is movable up and down. The positioning force transmission rod is supported by the compression springs on both sides. The positioning force transmission rod passes through the mandrel laterally perpendicular to the mandrel axis and is fixed to the mandrel. The central top cylinder is located below the mandrel and is movable between the position where it is engaged with the mandrel and supports the mandrel and the position where it is disengaged from the mandrel. The force forks are distributed in mutually perpendicular directions on the mandrel journal. A vibrator is installed at a 45° position on the lower right and lower left of the mandrel. The vibrator is connected to the force fork to apply a simple harmonic excitation force to the center of the mandrel.

[0009] The extrusion oil film damper includes an outer oil film ring and a stop ring; a cylindrical boss is provided in the middle of the mandrel; the front end face of the boss contacts the outer oil film ring, and the rear end contacts the stop ring; the outer oil film ring and the stop ring provide axial constraint for the mandrel.

[0010] Preferably, the positioning force transmission rod is provided with symmetrical mounting holes, the spring rotating component passes through the mounting holes and is connected to the upper end of the spring, and the lower end of the spring is connected to the two pull cylinders.

[0011] Preferably, the base is located directly below the auxiliary testing device and is connected to the two side pull cylinders and the middle top cylinder by threads, and the base is symmetrical about the middle threaded column.

[0012] Preferably, the upper surface of the intermediate top cylinder is in contact with the inner surface of a specific groove on the mandrel; the upper part of the intermediate top cylinder is provided with a small vent hole, and the upper parts of the two pull cylinders are provided with small vent holes.

[0013] Preferably, the front end of the outer oil film ring is connected to the front end cap, and the rear end is connected to the bushing; the front end of the spring ring contacts the stop ring, the rear end of the spring ring contacts the rear end cap, and the rear end cap is connected to the bushing; the axes of the front end cap, the rear end cap, the outer oil film ring, the stop ring, the spring ring, and the bushing are collinear.

[0014] Preferably, the front end cover is provided with an oil inlet and an oil inlet pipe connected to it, and the position is located on a part of the front end cover; the oil passage is part of the outer ring of the oil film; the oil outlet channel is formed by the groove surface of the spindle and the protruding surface of the stop ring, and the oil outlet channel is connected to the oil outlet.

[0015] Preferably, the bushing is bolted to the support, and the oil baffle is connected to the support.

[0016] Preferably, the outer ring of the oil film is provided with a threaded hole, which is connected to the sensor.

[0017] The beneficial effects of the technical solution of the present invention are as follows:

[0018] (1) It can simulate the dynamic eccentricity of a non-centering SFD caused by rotor gravity under variable frequency excitation, thereby obtaining the influence of dynamic eccentricity on the dynamic characteristics of the non-centering SFD.

[0019] (2) No force measuring device is required. The structural design solves the problem of constant initial preload or initial axial position positioning of non-centering SFD, reduces the structural complexity of the test device, simplifies the design difficulty, and saves processing costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a centering SFD dynamic characteristics test device.

[0021] Figure 2 This is a schematic diagram showing the installation positions of the mandrel, positioning force transmission rod, spring rotating component, and intermediate top cylinder.

[0022] Figure 3 This is a schematic diagram showing the position of the force transmission rod.

[0023] Figure 4 This is a schematic diagram of the central top tube.

[0024] Figure 5 This is a schematic diagram of the two pull tubes.

[0025] Figure 6 This is a diagram of the overall structure of the auxiliary experimental device.

[0026] Figure 7 This is a schematic diagram showing the installation positions of the front cover, spindle, and rear cover.

[0027] Figure 8 This is a schematic diagram showing the installation positions of the mandrel, retaining ring, and spring ring.

[0028] Figure 9 This is a partial schematic diagram of the outer ring of the oil film.

[0029] Figure 10 This is a schematic diagram of the front cover.

[0030] Figure 11 A schematic diagram of the stop ring.

[0031] Figure 12 This is a structural diagram of the experimental setup.

[0032] The components include: 1. Spring rotating component; 2. Positioning force transmission rod; 3. Pull cylinder; 4. Base; 5. Mandrel; 6. Spring; 7. Top cylinder; 8. Mounting hole; 9. Inner surface of groove; 10. Vent hole; 11. Vent hole; 12. Front end cover; 13. Support; 14. Bushing; 15. Outer ring of oil film; 16. Rear end cover; 17. Oil baffle plate; 18. Stop ring; 19. Spring ring; 20. Oil inlet; 21. Position; 22. Oil outlet channel; 23. Oil outlet; 24. Oil passage; 25. Threaded hole; 26. Force fork; 27. Vibrator; 28. End face; 29. ​​Protruding surface of stop ring; 30. Boss. Detailed Implementation

[0033] This embodiment is a test apparatus for simulating the dynamic characteristics of a non-centering SFD structure, solving the structural problems of applying rotor gravity and axial preload in the design of the test apparatus. This embodiment is used for a test apparatus for simulating the dynamic characteristics of a non-centering SFD structure. The implementation of the invention will be further described below with reference to the accompanying drawings.

[0034] Please combine Figure 9 As shown, the test device for simulating rotor static eccentricity and applying additional gravity includes a mandrel 5, a positioning force transmission rod 2, a spring rotation component 1, a spring 6, two side pull cylinders 3, a middle top cylinder 7, a base 4, a front end cover 12, a rear end cover 16, an oil film outer ring 15, a stop ring 18, a spring ring 19, a bushing 14, and a force fork 26, wherein: Figure 1 As shown, the positioning force transmission rod 2 is mounted on the spindle 5, located above the spring 6 and the intermediate top cylinder 7; the upper end of the spring 6 is connected to the spring rotating component 1, and the lower end is connected to the two side pull cylinders 3; the upper ends of the two side pull cylinders 3 are connected to the spring 6, and the lower ends are connected to the base 4 via threads; the base 4 is located directly below the entire device, and is connected to the two side pull cylinders 3 and the intermediate top cylinder 7 via threads respectively, and the base 4 is symmetrical about the intermediate threaded post. Figure 7 As shown, the front cover 12 is positioned and connected to the outer ring 15 of the oil film by a locating pin, the front end of the bushing 14 is connected to the outer ring 15 of the oil film by bolts, the rear cover 16 is positioned and connected to the bushing 14 by circumferential and axial positioning, the bushing 14 is connected to the support 13 by bolts, and the oil baffle 17 is connected to the support 13. Figure 8 As shown, the spindle 5 contacts the stop ring 18 through the end face 28, the stop ring 18 axially positions the spindle 5, the spring ring 19 contacts the stop ring 18, and the rear end cover 16 axially positions the spring ring 19.

[0035] like Figure 2 As shown, the intermediate top cylinder 7 is located below the mandrel 5, and the upper surface of the intermediate top cylinder 7 is in contact with the inner surface 9 of a specific groove on the mandrel 5. The spring rotating component 1 is located on the positioning force transmission rod mounting hole 8, in the symmetrical direction of the positioning force transmission rod 2.

[0036] like Figure 3 As shown, the axis of the entire device except for the mandrel 5 is located in the same plane; the positioning force transmission rod 2 is connected to the mandrel 5 by threads, and the lengths of the two ends of the positioning force transmission rod 2 extending out of the mandrel 5 should be the same. This can be judged by the number of exposed thread turns, i.e., whether n1 is equal to n2, so as to reduce the influence of the additional torque of the spring force on the shaft of the mandrel 5; the spring rotating component 1, the spring 6, and the two pull cylinders 3 should be coaxial to avoid the spring force on both sides being unequal.

[0037] like Figure 4 , Figure 5 As shown, the intermediate top cylinder 7 is an important component for adjusting the position of the mandrel 5. Since it is connected to the base 4 by threads, when the top cylinder 7 rotates 360 degrees, it rises or falls by one thread pitch. Therefore, when the top cylinder 7 rotates 1 degree, the distance it rises or falls will also meet the position requirements of the mandrel 5, that is, achieve the requirement of adjusting the oil film eccentricity. The threads connecting the base 4 and the intermediate top cylinder 7 have different thread pitches, which will achieve different adjustment accuracies. The two side pull cylinders 3 can also convert the rotation angle of the pull cylinder 3 into the axial deformation of the spring 6, which can precisely control the applied spring force. The intermediate top cylinder 7 and the two side pull cylinders 3 have small vent holes 10 and 11 near their upper parts.

[0038] like Figure 2 , Figure 1 As shown, the two symmetrical spring rotating components 1 should have the same size, the two springs 6 should be of the same specification, that is, the spring stiffness should be equal, and the two pull cylinders 3 should have the same size, so that the axial displacement generated by the two pull cylinders 3 is the same.

[0039] like Figure 6 As shown, the entire device, excluding the mandrel 5, consists of two sets symmetrically distributed about a plane perpendicular to the axis of the mandrel 5. This avoids generating additional torque on the mandrel 5. After the mandrel 5 is pushed to a precise position by the central top cylinder 7, the mandrel 5 is fixed in this precise position by the test bench device. The central top cylinder 7 will then rotate and move downwards, disengaging from the surface in contact with the mandrel 5. The two side pull cylinders 3 will rotate and move downwards, pulling the spring 6 until the two side pull cylinders 3 reach the designated position, at which point the spring 6 will generate a precise pulling force on the mandrel 5.

[0040] like Figure 8 As shown, the oil inlet 20 of the front cover 12 is connected to the oil inlet pipe by a thread, and the oil enters the front cover 12 at position 21, as shown. Figure 10 As shown, position 21 is a part of the oil passage located at the front end cover 12. Subsequently, the oil flows through oil passage 24 of the outer oil film ring 15, as... Figure 9As shown, oil passage 24 is a part of the oil passage located in the outer ring 15 of the oil film. Oil forms an oil film between the outer ring 15 and the spindle 5. The oil outlet channel 22 is formed by the groove surface of the spindle 5 and the protruding surface 29 of the stop ring. Oil flows out through the oil outlet 23.

[0041] like Figure 8 As shown, the non-centering extrusion oil film damper has no elastic support, but it needs to prevent the spindle 5 from moving axially. Therefore, the spindle 5 needs a certain initial preload. The rear end cover 16 axially constrains the spring ring 19. Through the design of the part dimensions, the spring ring 19 will generate a certain amount of compression after assembly, and the spring ring 19 will have a certain axial force. Figure 11 As shown, the spring coil 19 cannot directly contact the spindle 5, so a stop ring 18 is introduced to apply a preload to the spindle 5. Figure 9 As shown, the threaded hole 25 is connected to the sensor via a thread, and is connected to the oil pressure sensor to record changes in oil film pressure.

[0042] like Figure 12 As shown, the force forks 26 are distributed in mutually perpendicular directions on the journal of the spindle 5. A vibrator 27 is installed at a 45° position on the lower right and lower left of the spindle 5. The vibrator 27 is connected to the force forks 26 and applies a simple harmonic excitation force to the center of the spindle 5. The simple harmonic forces on the two vibrators 27 have the same frequency and amplitude, and the phase difference is 90°, thereby simulating the excitation force generated by the circular motion of a statically eccentric shaft.

[0043] like Figure 12 As shown, before assembling this test device, first place the front end cover 12 and the oil film outer ring 15 on the side of the spindle 5 without grooves, and place the stop ring 18, spring ring 19 and rear end cover 16 on the side of the spindle 5 with grooves. Use the intermediate top cylinder 7 in the auxiliary test device to lift the spindle 5 into a suitable position, and then install the oil film outer ring 15, front end cover 12, stop ring 18, spring ring 19 and rear end cover 16 in sequence. Connect the force fork 26 to the spindle 5 with bolts, and finally the spring 6 in the auxiliary test device.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A test apparatus for simulating the structure of a non-centering extrusion oil film damper, characterized in that, Includes a spindle (5), several forks (26), two load-bearing components, and a squeeze oil film damper; Two identical load-bearing components are respectively supported at the front and rear ends of the mandrel (5). Each load-bearing component includes a positioning force transmission rod (2), a central top cylinder (7), compression springs (6) symmetrically arranged on both sides of the positioning force transmission rod (2), and two side pull cylinders (3) supporting the compression springs. The central top cylinder (7) is movable up and down. The positioning force transmission rod (2) is supported by the compression springs (6) on both sides. The positioning force transmission rod (2) passes through the mandrel (5) laterally perpendicular to the axis of the mandrel (5) and is fixed to the mandrel (5). The intermediate top cylinder (7) is located below the mandrel (5), and the intermediate top cylinder (7) is movable between the joint with the mandrel (5) and the position of bearing the mandrel (5) and the position of disengaging from the mandrel (5); the force forks (26) are distributed in mutually perpendicular directions on the journal of the mandrel (5), and a vibrator (27) is installed at a position 45° to the lower right and 45° to the lower left of the mandrel (5), and the vibrator (27) is connected to the force forks (26) to apply a simple harmonic excitation force to the center of the mandrel (5); The extrusion oil film damper includes an outer oil film ring (15) and a stop ring (18); a cylindrical boss (30) is provided in the middle of the mandrel (5); the front end face of the boss (30) contacts the outer oil film ring (15), and the rear end contacts the stop ring (18); the outer oil film ring (15) and the stop ring (18) axially constrain the mandrel (5).

2. The experimental apparatus for simulating a non-centering extrusion oil film damper structure according to claim 1, characterized in that, The positioning force transmission rod (2) is provided with symmetrical mounting holes (8). The spring rotating component (1) passes through the mounting holes (8) and is connected to the upper end of the compression spring (6). The lower end of the spring (6) is connected to the two side pull tubes (3).

3. The test apparatus for simulating a non-centering extrusion oil film damper structure according to claim 2, characterized in that, The base (4) is located directly below the test device and is connected to the two side pull tubes (3) and the middle top tube (7) by threads respectively. The base (4) is symmetrical about the middle top tube (7).

4. The test apparatus for simulating a non-centering extrusion oil film damper structure according to claim 3, characterized in that, The upper surface of the intermediate top cylinder (7) is in contact with the inner surface (9) of the groove on the spindle (5); the upper part of the intermediate top cylinder (7) is provided with a small exhaust hole, and the upper parts of the pull cylinders (3) on both sides are provided with small exhaust holes.

5. The test apparatus for simulating a non-centering extrusion oil film damper structure according to claim 1, characterized in that, The front end of the oil film outer ring (15) is connected to the front end cap (12), and the rear end is connected to the bushing (14); the front end of the spring ring (19) is in contact with the stop ring (18), the rear end of the spring ring (19) is in contact with the rear end cap (16), and the rear end cap (16) is connected to the bushing (14); the axes of the front end cap (12), the rear end cap (16), the oil film outer ring (15), the stop ring (18), the spring ring (19), and the bushing (14) are collinear.

6. The test apparatus for simulating a non-centering extrusion oil film damper structure according to claim 5, characterized in that, The oil inlet (20) on the front end cover (12) is connected to the oil inlet pipe. The front end cover (12) is also provided with a position (21), which is connected to the oil inlet (20). The outer ring (15) of the oil film is provided with an oil passage (24) for the flow of oil. The oil outlet channel (22) is formed by the groove surface of the spindle (5) and the protruding surface (29) of the stop ring. The oil outlet channel (22) is connected to the oil outlet (23).

7. The test apparatus for simulating a non-centering extrusion oil film damper structure according to claim 5, characterized in that, The bushing (14) is connected to the support (13) by bolts, and the oil baffle (17) is connected to the support (13).

8. The test apparatus for simulating a non-centering extrusion oil film damper structure according to claim 5, characterized in that, The outer ring (15) of the oil film is provided with a threaded hole (25), which is connected to the sensor.

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