Compliant variable stiffness curved beam supported ultra-low frequency vibration isolation device

Abstract

The application discloses a compliant variable stiffness curved beam supporting ultra-low frequency vibration isolation device, which comprises a main frame, a main connecting rod movably arranged in the main frame, and a negative stiffness mechanism and a positive stiffness mechanism coupled in parallel to the main connecting rod, wherein the negative stiffness mechanism with nonlinear negative stiffness is sleeved on the main connecting rod, the positive stiffness mechanism with nonlinear positive stiffness is fixed at one end on the main frame and is fixedly connected at the other end with the main connecting rod, the nonlinear positive stiffness mechanism is used for modulating the nonlinear negative stiffness mechanism, and the high static stiffness and low dynamic stiffness characteristics are realized. The application adopts the arc-shaped beam with double-end clamping to provide the nonlinear negative stiffness, adopts the spiral-shaped beam to provide the nonlinear positive stiffness and the guiding function, and adopts the parallel arc-shaped beam and spiral-shaped beam to realize the high static stiffness and low dynamic stiffness characteristics. The stiffness of the vibration isolation device only needs to be modulated by adjusting the coupling connection relationship of the positive stiffness mechanism and the negative stiffness mechanism, the configuration parameters of the elastic elements do not need to be changed or the elements do not need to be replaced, the stiffness modulation is flexible, and the ultra-low dynamic stiffness can be easily realized. The vibration isolation device adopts the compliant design, is convenient to assemble, has no motion gap and contact friction limitation, and can realize the ultra-low frequency vibration isolation.

Description

Technical Field

[0001] This invention relates to a technology in the field of vibration isolation, specifically a flexible variable stiffness curved beam supported ultra-low frequency vibration isolation device. Background Technology

[0002] The stiffness modulation of traditional quasi-zero stiffness isolators relies on the nonlinear stiffness variation of a bistable mechanism. However, changing the nonlinear stiffness of a bistable mechanism requires consistent adjustment of the configuration parameters of multiple elastic elements or replacement of the elastic elements, making stiffness modulation of the isolator inconvenient and difficult to achieve ultra-low frequency vibration isolation. Furthermore, the kinematic pairs in classic bistable mechanisms and guiding mechanisms exhibit gap collisions and contact friction behaviors, which severely affect the generation of bistable nonlinear stiffness and greatly hinder the achievement of low-frequency vibration isolation performance. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies that cannot achieve low dynamic stiffness and thus cannot realize ultra-low frequency vibration isolation. It proposes a compliant variable stiffness curved beam-supported ultra-low frequency vibration isolation device. A double-end clamped arc-shaped beam provides nonlinear negative stiffness, while a helical beam provides nonlinear positive stiffness and guidance. The parallel connection of the arc-shaped and helical beams achieves high static stiffness and low dynamic stiffness characteristics. Since the stiffness nonlinearity is contributed by both the negative and positive stiffness mechanisms, the stiffness of the isolation device can be modulated simply by adjusting the coupling relationship between the positive and negative stiffness mechanisms, without changing the configuration parameters of the elastic elements or replacing any components. This flexible stiffness modulation easily achieves extremely low dynamic stiffness. The vibration isolation device features a compliant design, is easy to assemble, and has no limitations on movement clearance or contact friction, enabling ultra-low frequency vibration isolation.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a compliant variable stiffness curved beam support for ultra-low frequency vibration isolation device, comprising: a main frame, a main connecting rod movably disposed therein, and a negative stiffness mechanism and a positive stiffness mechanism coupled in parallel to the main connecting rod, wherein: the negative stiffness mechanism with nonlinear negative stiffness is sleeved on the main connecting rod, and the positive stiffness mechanism with nonlinear positive stiffness is fixed at one end to the main frame and fixedly connected at the other end to the main connecting rod, thereby modulating the nonlinear negative stiffness mechanism through the nonlinear positive stiffness mechanism to achieve high static stiffness and low dynamic stiffness characteristics.

[0006] The main frame includes: a base, a lower frame, a middle frame, an upper frame, and a pressure ring connected in sequence, wherein: the upper frame is connected to the negative stiffness mechanism and the positive stiffness mechanism respectively, and the lower frame is connected to the positive stiffness mechanism.

[0007] The negative stiffness mechanism includes: several arc-shaped beams, a vertical fixed seat and a horizontal fixed seat, wherein: the vertical fixed seat is fixedly connected to the main frame, the horizontal fixed seat is connected to the main connecting rod, and the two ends of the several arc-shaped beams are respectively connected to the vertical fixed seat and the horizontal fixed seat.

[0008] The positive stiffness mechanism includes a first diaphragm spring and a second diaphragm spring coaxially arranged on the main connecting rod, wherein the first diaphragm spring is connected to the lower frame and the second diaphragm spring is connected to the upper frame.

[0009] The diaphragm spring has a radial stiffness much greater than its axial stiffness, and thus has a guiding function.

[0010] The ultra-low frequency vibration isolation refers to: adjusting the limit nut to change the coupling connection relationship of the compliant positive and negative stiffness mechanism, realizing flexible modulation of the stiffness of the vibration isolation device, forming high static stiffness and low dynamic stiffness characteristics, and the low frequency vibration isolation performance is not limited by the movement gap and contact friction. Technical effect

[0011] This invention achieves high static stiffness and low dynamic stiffness nonlinear vibration isolation through a parallel connection of an arc-shaped beam with nonlinear negative stiffness and a helical beam with nonlinear positive stiffness. The vibration isolation performance is not limited by movement gaps or contact friction. The dynamic stiffness of the isolator is modulated by changing the coupling relationship between the nonlinear negative stiffness mechanism and the nonlinear positive stiffness mechanism, avoiding changes to the configuration parameters of the elastic element or replacement of the elastic element. Compared with existing technologies, this invention does not rely on adjusting or replacing the elastic element of the negative stiffness mechanism; only the limiting nut needs to be adjusted to change the coupling relationship between the positive and negative stiffness mechanisms. Stiffness modulation is convenient and flexible, and extremely low dynamic stiffness is more easily obtained. The vibration isolation device adopts a compliant support design, and the generation of dynamic stiffness is not limited by the gaps and friction of the moving parts, thus achieving ultra-low frequency vibration isolation performance. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the ultra-low frequency vibration isolation device of the present invention;

[0013] Figure 2 This is a schematic diagram of the assembly of a negative stiffness structure.

[0014] Figure 3 This is a schematic diagram of a structure with positive stiffness.

[0015] Figure 4 This is a schematic diagram of the assembly of the positive stiffness structure and the main connecting rod;

[0016] Figure 5 , Figure 6 and Figure 7 The force-displacement curves are shown for ultra-low frequency vibration isolation devices, negative stiffness mechanisms, and positive stiffness mechanisms, respectively.

[0017] Figures 8-10 This is a curve showing the stiffness modulation process of the vibration isolation device of the present invention;

[0018] In the diagram: 1. Base, 2. Lower frame, 3. Middle frame, 4. Upper frame, 5. Pressure ring, 6. Mass block, 7. Locking nut, 8. Loading screw, 9. Second bolt, 10. Third bolt, 11. Fourth bolt, 12. Fifth bolt, 13. Sixth bolt, 14. Arc beam, 15. Horizontal fixed seat, 16. Horizontal clamping block, 17. Seventh bolt, 18. First limit nut, 19. Second limit nut, 20. Horizontal fixed seat, 21. Vertical clamping block, 22. Eighth bolt, 23. First diaphragm spring, 24. Main connecting rod, 25. Second diaphragm spring. Detailed Implementation

[0019] like Figures 1-3 As shown in the figure, this embodiment relates to a compliant variable stiffness curved beam support ultra-low frequency vibration isolation device, including: a main frame, a main connecting rod 24 movably disposed therein, and a negative stiffness mechanism and a positive stiffness mechanism coupled in parallel to the main connecting rod 24, wherein: the negative stiffness mechanism with nonlinear negative stiffness is sleeved on the main connecting rod 24, and the positive stiffness mechanism with nonlinear positive stiffness is fixed at one end to the main frame and fixedly connected at the other end to the main connecting rod 24.

[0020] The main frame includes: a base 1, a lower frame 2, a middle frame 3, an upper frame 4, and a pressure ring 5 connected in sequence, wherein: the upper frame 4 is connected to the negative stiffness mechanism and the positive stiffness mechanism respectively, and the lower frame 2 is connected to the positive stiffness mechanism.

[0021] The lower frame 2, middle frame 3, and upper frame 4 are hollow cylinders with notches.

[0022] The main connecting rod 24 is a single-ended screw with internal threaded holes at both ends. A first limiting nut 18 and a second limiting nut 19 connected to the negative stiffness mechanism are screwed onto the connecting rod to adjust the coupling connection relationship between the positive and negative stiffness structures.

[0023] like Figure 2 As shown, the negative stiffness mechanism includes: several arc-shaped beams 14, a vertical fixed seat 20 and a horizontal fixed seat 15, wherein: the vertical fixed seat 20 is fixedly connected to the main frame, the horizontal fixed seat 15 is connected to the main connecting rod 24, and the two ends of the several arc-shaped beams 14 are respectively connected to the vertical fixed seat 20 and the horizontal fixed seat 15.

[0024] The vertical fixing seat 20 and the horizontal fixing seat 15 are each provided with a plurality of arrayed grooves and clamping blocks for connecting the two ends of the arc beam 14. Specifically, the vertical clamping block 21 and the horizontal clamping block 16 are respectively clamped to the arc beam by the sixth bolt 13 and the seventh bolt 17.

[0025] The vertical fixing seat 20 and the upper frame 4 are fixedly connected by the third bolt 10. The horizontal fixing seat 15 and the horizontal clamping block 16 are fixedly connected to the main connecting rod 24 by the first limiting nut 18 and the second limiting nut 19. The position of the horizontal fixing seat 15 on the main connecting rod 24 can be changed by adjusting the first limiting nut 18 and the second limiting nut 19.

[0026] The arc-shaped beams 14 are preferably six in number and are evenly distributed around the vertical fixing base 20 in a circumferential manner.

[0027] like Figure 3 As shown, the positive stiffness mechanism includes a first diaphragm spring 23 and a second diaphragm spring 25 coaxially arranged on the main connecting rod 24, wherein the first diaphragm spring 23 is connected to the lower frame 2, and the second diaphragm spring 25 is connected to the upper frame 4.

[0028] The diaphragm springs 23 and 25 are each provided with a helical beam, a central hole, and a circumferential array of holes.

[0029] The spiral shape is preferably formed using a constant velocity spiral as the contour line.

[0030] The radial stiffness of the first diaphragm spring 23 and the second diaphragm spring 25 is much greater than the axial stiffness, thus providing a guiding function.

[0031] The first diaphragm spring 23 is fixed to the lower frame 2 on the outside by the fourth bolt 11, and fixed to the main connecting rod 24 on the inside by the eighth bolt 22; the second diaphragm spring 25 is fixed to the upper frame 4 on the outside by the second bolt, and fixed to the main connecting rod 24 on the inside by the loading screw 8.

[0032] The loading screw 8 and the mass block 6 are fixedly connected by a locking nut 7.

[0033] like Figure 5 As shown, when the two ends of the arc beam 14 are clamped and constrained, with no movement gaps and contact friction, the force-displacement relationship obtained through static analysis has nonlinear negative stiffness characteristics.

[0034] like Figure 6 As shown, when the two ends of the first diaphragm spring 23 and the second diaphragm spring 25 are clamped and constrained, and there are no kinematic pairs or contact friction, the force-displacement relationship obtained by static analysis has nonlinear positive stiffness characteristics.

[0035] like Figure 7 As shown, the vibration isolation device utilizes a nonlinear positive stiffness structure to modulate a nonlinear negative stiffness structure to achieve high static stiffness and low dynamic stiffness characteristics.

[0036] like Figures 8-10As shown, when the first limiting nut 18 and the second limiting nut 19 are adjusted, the static analysis results show that the force-displacement curve of the negative stiffness structure can be shifted, the nonlinear positive and negative stiffness coupling relationship can be changed, and the stiffness of the structure can be flexibly modulated to positive stiffness, quasi-zero stiffness and negative stiffness.

[0037] Compared with existing technologies, this invention utilizes an arc-shaped beam 14 to provide a nonlinear negative stiffness mechanism, and a first diaphragm spring 23 and a second diaphragm spring 25 to provide nonlinear positive stiffness, achieving compliant nonlinear vibration isolation with high static stiffness and low dynamic stiffness. The stiffness modulation of the isolation device does not depend on adjusting or replacing the elastic elements of the negative stiffness mechanism; only the first limiting nut 18 and the second limiting nut 19 need to be adjusted to change the coupling connection relationship between the positive and negative stiffness mechanisms. Stiffness modulation is convenient and flexible, and it is easier to obtain extremely low dynamic stiffness. The arc-shaped beam 14, the first diaphragm spring 23, and the second diaphragm spring 25 are clamped and constrained at both ends. The first diaphragm spring 23 and the second diaphragm spring 25 have a guiding function, and the generation of dynamic stiffness is not limited by the clearance and friction of the moving parts, thus achieving ultra-low frequency vibration isolation performance.

[0038] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A compliant variable stiffness curved beam support for ultra-low frequency vibration isolation device, characterized in that, include: The main frame, the main connecting rod that is movably set therein, and the negative stiffness mechanism and the positive stiffness mechanism that are coupled in parallel to the main connecting rod, wherein: the negative stiffness mechanism with nonlinear negative stiffness is sleeved on the main connecting rod, and the positive stiffness mechanism with nonlinear positive stiffness is fixed at one end to the main frame and fixedly connected to the main connecting rod at the other end. The nonlinear negative stiffness mechanism is modulated by the nonlinear positive stiffness mechanism to achieve high static stiffness and low dynamic stiffness characteristics. The main frame includes: a base, a lower frame, a middle frame, an upper frame, and a pressure ring connected in sequence, wherein: the upper frame is connected to the negative stiffness mechanism and the positive stiffness mechanism respectively, and the lower frame is connected to the positive stiffness mechanism. The negative stiffness mechanism includes: several arc-shaped beams, a vertical fixed seat and a horizontal fixed seat, wherein: the vertical fixed seat is fixedly connected to the main frame, the horizontal fixed seat is connected to the main connecting rod, and the two ends of the several arc-shaped beams are respectively connected to the vertical fixed seat and the horizontal fixed seat; The positive stiffness mechanism includes a first diaphragm spring and a second diaphragm spring coaxially arranged on the main connecting rod, wherein the first diaphragm spring is connected to the lower frame and the second diaphragm spring is connected to the upper frame.

2. The compliant variable stiffness curved beam-supported ultra-low frequency vibration isolation device according to claim 1, characterized in that, The diaphragm spring described above has a radial stiffness much greater than its axial stiffness, and thus has a guiding function; The diaphragm spring is provided with a helical beam, a central hole, and a circumferential array of holes.

3. The compliant variable stiffness curved beam-supported ultra-low frequency vibration isolation device according to claim 1 or 2, characterized in that, The first diaphragm spring is fixed to the lower frame on the outside by the fourth bolt and to the main connecting rod on the inside by the eighth bolt; the second diaphragm spring is fixed to the upper frame on the outside by the second bolt and to the main connecting rod on the inside by the loading screw.

4. The compliant variable stiffness curved beam-supported ultra-low frequency vibration isolation device according to claim 1, characterized in that, The main connecting rod is a single-ended screw with internal threaded holes at both ends. A first limiting nut and a second limiting nut connected to the negative stiffness mechanism are screwed onto the connecting rod to adjust the coupling connection relationship between the positive and negative stiffness structures. The ultra-low frequency vibration isolation refers to: adjusting the limit nut to change the coupling connection relationship of the compliant positive and negative stiffness mechanism, realizing flexible modulation of the stiffness of the vibration isolation device, forming high static stiffness and low dynamic stiffness characteristics, and the low frequency vibration isolation performance is not limited by the movement gap and contact friction.

5. The compliant variable stiffness curved beam-supported ultra-low frequency vibration isolation device according to claim 1, characterized in that, The vertical and horizontal fixing seats are each provided with several arrayed grooves and clamping blocks for connecting the two ends of the arc beam. Specifically, the vertical clamping blocks and the horizontal clamping blocks are respectively clamped to the arc beam by the sixth bolt and the seventh bolt.

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