Non-circular constant-width curve floating ring oil film damper

Abstract

The present application relates to a kind of non-circular fixed-width curve floating ring oil film damper, including damper journal, damper outer ring and the floating ring between damper journal and damper outer ring, the outer ring of floating ring section is floating ring outer ring fixed-width curve, the inner ring of damper outer ring section is equipped with the damper outer ring fixed-width curve that is adapted to floating ring outer ring fixed-width curve, floating ring and damper outer ring between constitute evenly distributed outer oil film, when floating ring once relative to damper outer ring appears self-rotating tendency in floating process, floating ring outer ring fixed-width curve and damper outer ring fixed-width curve between form multiple wedge-shaped gaps connected head to tail, oil film pressure is greater at gap thinner place, change generated by oil film pressure distribution dynamically generates return torque to floating ring, the present application retains the advantages of floating ring extrusion oil film damper while overcoming the deficiency, solve the defect of floating ring extrusion oil film damper in aero-engine application, it is particularly important for improving the technical maturity and application promotion of FSFDs.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil film dampers, in particular to a non-circular fixed-width curve floating ring oil film damper. BACKGROUND

[0002] Squeeze film dampers (SFDs) are a kind of supporting damping structure devices commonly used in aero-engines. Through the fluid dynamic pressure effect generated by the precession of the damper shaft neck, the dynamic characteristics of the rotor system are improved to realize the improvement of the rotor system's ability to pass through the critical speed, vibration reduction and reduction of bearing force transmission, etc.

[0003] When the system parameters are not properly designed, due to the effect of the squeeze film damper, the rotor system may produce bistable vibration phenomenon, amplitude jump behavior and non-coordinated precession response, which endangers the safe operation of the aero-engine. Floating ring squeeze film dampers (FSFDs) have been proven to effectively overcome the shortcomings of squeeze film dampers. Floating ring squeeze film dampers (FSFDs) can overcome the bistable response and non-coordinated precession of the rotor system caused by the highly nonlinear oil film reaction force of the traditional squeeze film damper, suppress cavitation cavitation, and improve the oil film nonlinearity. However, compared with ordinary dampers, the floating ring squeeze film damper increases the complexity of the system due to the addition of a movable part, which also causes some potential problems, such as solid contact and friction caused by the positioning pin or boss used to limit the rotation of the floating ring (to prevent damper failure).

[0004] The damper shaft neck of the squeeze film damper deviates from the geometric center during work and does not rotate, and the relative movement between the damper shaft neck and the damper outer wall surface is translational, and cannot appear relative rotation or sliding, otherwise the squeeze film cannot play a role in reducing vibration, but will increase the amplitude of the engine rotor (damper failure). Therefore, the concentric squeeze film damper ensures that the damper shaft neck and the damper outer ring do not rotate relative to each other by installing a squirrel cage elastic support, and the non-concentric squeeze film damper ensures that the damper shaft neck and the damper outer ring do not rotate relative to each other by installing an anti-rotation pin.

[0005] In order to prevent the floating ring from rotating to cause the damper to fail, for the floating ring extrusion oil film damper, it is necessary to ensure that the floating ring does not rotate or slide relative to the damper shaft neck, so in actual application, certain improvement is often made on the structure to limit the rotation. The common methods for limiting the floating ring include installing a positioning pin and increasing a boss on the floating ring. The positioning pin is installed by opening a hole slightly larger than the cross section of the positioning pin on the floating ring, and the positioning pin is fixed to the outer ring of the damper when the positioning pin passes through the hole (clearance fit). The boss on the floating ring is two protrusions processed on the arc surface of the floating ring, which are distributed at 180° on the diameter line close to the end surface of the floating ring, and the floating ring needs to be placed into the corresponding gap of other components of the damper with the boss during installation.

[0006] According to the geometric conditions generated by the hydrodynamic pressure effect, liquid needs to flow through the wedge-shaped gap, and there is relative motion between the wall surfaces on both sides of the gap. At most, two wedge-shaped gaps can be formed in the floating process of the circular ring.

[0007] The floating ring of the partial floating ring extrusion oil film damper has an elastic support, and the floating range is small and self-rotation does not occur, but the damping effect is not as good as that of the full floating floating ring without the elastic support.

[0008] The floating ring is positioned by the positioning pin or the surface increases the boss to limit the self-rotation, which reduces the effective extrusion area of the arc surface of the floating ring and destroys the integrity of the oil film. The boss affects the center of gravity of the floating ring and affects the motion state of the floating ring. The positioning pin affects the circulation of the outer oil film of the floating ring.

[0009] The two ways of limiting the self-rotation of the floating ring by the positioning pin and the boss are basically to hinder the self-rotation of the floating ring by the reaction force (torque on the floating ring) generated by the small area of solid contact. Since the solid contact area is small (point contact or line contact), a large stress concentration is formed at the contact position. The continuous solid contact greatly increases the possibility of low-frequency modal of the floating ring, and has adverse effects on the service life and reliability of the floating ring.

[0010] Whether the positioning pin or the boss is used, the modification of the structure of the floating ring and the modification of other components of the damper reduce the reliability of the system. SUMMARY

[0011] The present application aims at the deficiencies of the prior art, and provides a non-circular fixed-width curved floating ring oil film damper.

[0012] The application is realized by the technical scheme, and provides a non-circular fixed-width curve floating ring oil film damper, which comprises a damper shaft neck, a damper outer ring and a floating ring located between the damper shaft neck and the damper outer ring, an outer layer oil film is formed between the floating ring and the damper outer ring, the damper outer ring is provided with oil supply holes which are communicated with the outer layer oil film, and the outer ring of the floating ring cross section is a floating ring outer ring fixed-width curve, and the inner ring of the damper outer ring cross section is provided with a damper outer ring fixed-width curve which is matched with the floating ring outer ring fixed-width curve.

[0013] As optimization, the outer ring of the damper shaft neck is provided with an annular groove, and the floating ring is arranged in the annular groove.

[0014] As optimization, the floating ring outer ring fixed-width curve comprises an odd number of arcs, and the number of the arcs is greater than or equal to 3.

[0015] As optimization, the floating ring outer ring fixed-width curve has an intersection with the damper outer ring fixed-width curve.

[0016] As optimization, the inner ring of the floating ring cross section is circular or a floating ring inner ring fixed-width curve.

[0017] As optimization, the oil supply holes are communicated with the middle position of the length direction of the floating ring.

[0018] As optimization, the number of the oil supply holes is equal to the number of the arcs of the floating ring outer ring fixed-width curve, and the oil supply holes are communicated with the middle position of the arcs.

[0019] The application has the following beneficial effects:

[0020] (1) The application retains the advantages of the full-floating floating ring extrusion oil film damper and improves the application maturity and practicality.

[0021] (2) The geometric center (i.e. the center) of the fixed-width curve circumscribed circle is different from the center of gravity of the floating ring, and the stability of the floating ring can be improved under the condition of reasonable design.

[0022] (3) The application avoids the solid contact low-frequency mode which may be generated by the traditional method of limiting the rotation of the floating ring, and the damage to the oil film integrity.

[0023] (4) The application can form multiple wedge-shaped oil film gaps, adaptively limit the rotation of the floating ring, make the stress of the floating ring more uniform, and improve the reliability.

[0024] (5) The curvature of the non-circular fixed-width curve is lower than that of the circular shape, and the extrusion effect of the generated oil film is better.

[0025] (6) The oil film is extruded to generate damping effect, the floating ring is floating and the rotation of the floating ring is limited at the same time, the space utilization rate of the oil is high, and the maintainability of the damper is high. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A sectional structure diagram of the present application;

[0027] Figure 2 A sectional structure diagram of the present application Figure 1 A sectional structure diagram of the present application;

[0028] Figure 3 A sectional structure diagram of the present application

[0029] Figure 4 A sectional structure diagram of the present application Figure 3 A sectional structure diagram of the present application;

[0030] Figure 5 A sectional structure diagram of the present application

[0031] Figure 6 A sectional structure diagram of the present application;

[0032] Figure 7 A sectional structure diagram of the present application

[0033] As shown in the figure:

[0034] 1, damper shaft neck, 2, damper outer ring, 3, floating ring, 4, oil supply hole, 5, bearing, 6, rotor, 7, outer oil film, 8, floating ring outer ring fixed width curve circumscribed circle, 9, floating ring outer ring fixed width curve inscribed regular polygon, 10, damper outer ring fixed width curve, 11, floating ring outer ring fixed width curve. DETAILED DESCRIPTION

[0035] In order to clearly illustrate the technical features of the present application, the present application will be described in detail below through specific embodiments.

[0036] As Figures 1-7 shown, the non-circular fixed width curve floating ring oil film damper of the present application comprises a damper shaft neck 1 and a damper outer ring 2, and the inner ring of the damper shaft neck 1 is connected with the rotor 6 through the bearing 5.

[0037] It also includes a floating ring 3 located between the damper shaft neck 1 and the damper outer ring 2, and the outer ring of the damper shaft neck 1 is provided with an annular groove, and the floating ring 3 is arranged in the annular groove. The two ends of the floating ring 3 are flat, and there is an oil film between the two ends, the inner ring and the outer ring of the floating ring 3, wherein the floating ring 3 and the damper outer ring 2 form an outer oil film 7, and the damper outer ring 2 is provided with an oil supply hole 4 communicating with the outer oil film 7. The oil supply hole 4 extends radially along the damper outer ring 2, and the oil supply hole 4 communicates with the middle position of the length direction of the floating ring 3, so that the oil enters the outer oil film 7 uniformly.

[0038] A convex closed curve on a plane, whose width in any direction is always constant regardless of how it is rotated, is called a constant-width curve or a constant-width curve. Each odd-numbered edge of a regular polygon can generate a constant-width curve by drawing a circular arc. Such constant-width curves are called Reuleaux polygons. Constant-width curves are composed of an odd number of identical circular arcs, such as the Reuleaux triangle (a three-sided constant-width curve), which is a common constant-width curve.

[0039] The inner circle of the floating ring 3 cross section is circular or a floating ring inner circle constant-width curve, and the corresponding annular groove bottom is also circular or a constant-width curve.

[0040] The outer circle of the floating ring 3 cross section is a floating ring outer circle constant-width curve 11, which is a Reuleaux polygon. The floating ring outer circle constant-width curve 11 includes an odd number of circular arcs, and the number of circular arcs is greater than or equal to 3. The inner circle of the damper outer circle 2 cross section is provided with a damper outer circle constant-width curve 10 that is adapted to the floating ring outer circle constant-width curve 11.

[0041] The number of oil supply holes 4 is equal to the number of circular arcs of the floating ring outer circle constant-width curve 11, and the oil supply holes 4 are connected to the middle positions of the circular arcs.

[0042] When the inner circle of the floating ring 3 is concentric with the damper journal 1, the gaps of the outer oil film 7 are uniformly distributed. As shown in Figure 3 , the dashed line of the regular heptagon is the floating ring outer circle constant-width curve inscribed regular polygon 9, and the circular dashed line is the floating ring outer circle constant-width curve circumscribed circle 8. It is known that for all non-circular constant-width curves, the circumscribed circle of the inscribed regular polygon is the circumscribed circle of the constant-width curve. In this embodiment, the circumscribed circle of the floating ring outer circle constant-width curve inscribed regular polygon 9 is the floating ring outer circle constant-width curve circumscribed circle 8.

[0043] Both solid lines are heptagonal constant-width curves, where the floating ring outer circle constant-width curve 11 has a smaller enclosed area, and the damper outer circle constant-width curve 10 has a larger enclosed area. As shown in Figure 4 , without using positioning pins or bosses, the floating ring 3 is entirely immersed in oil, and the gap thickness of the outer oil film 7 between the damper outer circle 2 and the floating ring 3 is uniform. When the damper journal 1 drives the floating ring 3 to move, the floating ring 3 outer circle wall surface extrudes the outer oil film 7, and the torque generated by the force of the outer oil film 7 adaptively limits the rotation of the floating ring 3.

[0044] The specific anti-rotation mechanism is as follows: when the floating ring 3 has a tendency to rotate relative to the damper outer circle 2 during floating, the floating ring outer circle constant-width curve 11 and the damper outer circle constant-width curve 10 form a plurality of wedge-shaped gaps connected head to tail. The oil film pressure is greater at the thinner gaps, and the change in oil film pressure distribution dynamically generates a restoring torque on the floating ring. As shown in Figure 5As shown, the floating ring outer width curve 11 has a tendency to rotate clockwise relative to the damper outer width curve 10, and the oil film gap is smaller at the position of the arrow, which generates greater oil film force, thus generating a counterclockwise righting moment on the floating ring.

[0045] If the aircraft engine rotor support system is subjected to aircraft maneuvering flight, especially aircraft roll maneuvering around the longitudinal axis of the aircraft body, the damper outer width curve 10 will be twisted relative to the floating ring, and multiple wedge-shaped gaps will be formed between the floating ring outer width curve 11 and the damper outer width curve 10. The torque generated by the roll maneuvering flight is transmitted to the outer surface of the floating ring 3 through the pressure of the outer oil film 7, so that the floating ring 3 does not rotate relative to the damper outer ring 2, but floats in a small range.

[0046] The geometric condition for the non-circular width curve floating ring oil film damper to limit the rotation of the floating ring is that the distance from a certain part of the damper outer width curve 10 to the center of the circumscribed circle 8 of the floating ring outer width curve is less than the radius of the circumscribed circle 8 of the floating ring outer width curve. That is, the circumscribed circle of the floating ring outer width curve 11 intersects the damper outer width curve 10.

[0047] To meet the geometric condition for the non-circular width curve damper to limit the rotation of the floating ring, the design criteria for the width curve floating ring damper can be derived. Assuming that the number of sides of the floating ring outer width curve is n (n = 3, 5, 7, 11…), the radius of the circumscribed circle of the floating ring outer width curve is R, and the radius of the damper outer width curve is r, the design criteria for the width curve floating ring damper to limit the rotation of the floating ring is: After the overall geometric parameters of the floating ring damper are dimensionless, the radius of the circumscribed circle of the floating ring outer width curve is converted to unit 1. The dimensionless width of the width curve is:

[0048]

[0049] According to the geometric condition for the non-circular width curve damper to limit the rotation of the floating ring, the corresponding design criteria for the width curve floating ring damper to prevent rotation is:

[0050]

[0051] Where C is the outer oil film gap.

[0052] According to the above design criteria, different width curve side numbers are brought into formula (2) to obtain a width curve side number and outer oil film gap design curve for the anti-rotation floating ring damper. Then The value of n must be below the design curve to ensure the limitation of the rotation of the floating ring, as shown in Figure 7 When the floating ring extrusion oil film damper outer oil film gap C is relatively fixed, the design criteria for limiting the rotation of the floating ring is met by adjusting the width curve side number n of the floating ring and the damper outer ring.

[0053] Of course, the above description is not limited to the above examples, and the technical features not described in the application can be implemented by or using the prior art, which will not be described here; the above examples and drawings are only used to illustrate the technical solutions of the application and are not a limitation on the application, and the application has been described in detail with reference to the preferred embodiments, and those skilled in the art should understand that changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the application do not deviate from the purpose of the application, and should also belong to the protection scope of the claims of the application.

Claims

1. A non-circular constant-width curve floating ring oil film damper, comprising a damper journal (1), a damper outer ring (2), and a floating ring (3) located between the damper journal (1) and the damper outer ring (2), wherein the floating ring (3) and the damper outer ring (2) form an outer oil film (7), and the damper outer ring (2) has an oil supply hole (4) communicating with the outer oil film (7), characterized in that: The outer ring of the floating ring (3) section is the floating ring outer ring fixed width curve (11), and the inner ring of the damper outer ring (2) section is provided with a damper outer ring fixed width curve (10) that is adapted to the floating ring outer ring fixed width curve (11); the circumcircle of the floating ring outer ring fixed width curve (11) and the damper outer ring fixed width curve (10) have an intersection point.

2. The non-circular constant-width curve floating ring oil film damper according to claim 1, characterized in that: The outer ring of the damper journal (1) is provided with an annular groove, and the floating ring (3) is disposed in the annular groove.

3. The non-circular constant-width curve floating ring oil film damper according to claim 1, characterized in that: The fixed-width curve (11) of the outer ring of the floating ring includes an odd number of arcs, and the number of arcs is greater than or equal to 3.

4. The non-circular constant-width curve floating ring oil film damper according to claim 1, characterized in that: The inner circle of the cross section of the floating ring (3) is circular or a fixed-width curve of the inner circle of the floating ring.

5. The non-circular constant-width curve floating ring oil film damper according to claim 1, characterized in that: The oil supply hole (4) is connected to the middle position of the float ring (3) in the length direction.

6. The non-circular constant-width curve floating ring oil film damper according to claim 1, characterized in that: The number of oil supply holes (4) is equal to the number of arcs of the fixed width curve (11) of the outer ring of the float ring, and the oil supply holes (4) are connected to the middle position of the arc.

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