Quasi-zero stiffness vibration isolator with adjustable negative stiffness and vibration isolation method

Abstract

The invention discloses a quasi-zero stiffness vibration isolator with adjustable negative stiffness. The quasi-zero stiffness vibration isolator comprises a base, a guide mechanism, a center shaft, a negative stiffness mechanism, a positive stiffness mechanism, a vibration isolation box body, an angle adjusting mechanism and a load platform, the base is horizontally arranged; the lower end of the central shaft is mounted in the base through a guide mechanism at the lower part; the positive stiffness mechanism and the negative stiffness mechanism are assembled on the central shaft from bottom to top and axially move along the central shaft; the positive stiffness mechanism is arranged in the vibration isolation box body; the angle adjusting mechanism is arranged outside the negative stiffness mechanism, and the output end of the angle adjusting mechanism is connected with the negative stiffness mechanism; the upper end of the center shaft is connected with the bottom of the load platform. The invention further discloses a vibration isolation method. The device has the beneficial effects that the overall structural design is simple, assembling is convenient and fast, maintaining is easy, and the machining, manufacturing and using cost is effectively reduced; the negative stiffness adjusting range of the vibration isolator is large, the vibration isolator can adapt to different load masses, the vibration isolator can be adjusted to be in an ideal quasi-zero stiffness state or be close to the ideal quasi-zero stiffness state, and the adaptability is wide.

Description

Technical Field

[0001] This invention relates to the field of vibration control and isolation technology, specifically to a quasi-zero stiffness vibration isolator with adjustable negative stiffness and a vibration isolation method. Background Technology

[0002] The quasi-zero stiffness vibration isolator achieves extremely low dynamic stiffness near the static equilibrium position through the parallel connection of positive and negative stiffness mechanisms, thereby reducing the system's natural frequency to an extremely low level and effectively isolating low-frequency and even ultra-low-frequency vibrations.

[0003] However, the negative stiffness characteristics of traditional quasi-zero stiffness isolators are typically provided by geometrically nonlinear structures (such as buckling beams or plates) or magnetic mechanisms with fixed parameters. Their force-displacement relationship is determined after design, meaning the system can only achieve the ideal "high static stiffness - low dynamic stiffness" characteristics under the designed rated load. When the actual load mass changes, the static equilibrium position of the system shifts, and the positive and negative stiffness mechanisms cannot perfectly cancel each other out at the deviated position, leading to a sharp increase in dynamic stiffness and a significant deterioration in vibration isolation performance. This is the main bottleneck limiting the engineering application of traditional quasi-zero stiffness isolators.

[0004] To address these issues, existing technologies have explored various methods. For example, active or semi-active control strategies are employed, using sensors, controllers, and actuators to adjust system parameters in real time. However, this method is structurally complex, costly, and its reliability is limited in harsh environments. Another approach involves mechanical adjustment, modifying the negative stiffness by changing the spacing between permanent magnets. However, this method has a limited adjustment range and the continuous adjustment mechanism is complex.

[0005] Therefore, developing a quasi-zero stiffness vibration isolator with a relatively simple structure, convenient adjustment, and the ability to adaptively or manually adjust within a wide load range to achieve positive and negative stiffness matching has significant theoretical and engineering value. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing an adjustable negative stiffness quasi-zero stiffness vibration isolator and vibration isolation method, aiming to solve the problems of complex structure and limited adjustment range in existing technologies.

[0007] The technical solution adopted in this invention is: an adjustable negative stiffness quasi-zero stiffness vibration isolator, comprising a base, a guide mechanism, a central shaft, a negative stiffness mechanism, a positive stiffness mechanism, a vibration isolator housing, an angle adjustment mechanism, and a load platform; The base is arranged horizontally; the lower end of the central shaft is installed in the base through a lower guide mechanism; The positive stiffness mechanism and the negative stiffness mechanism are assembled on the central shaft from bottom to top and can move axially along the central shaft; the positive stiffness mechanism is located inside the vibration isolation box; the angle adjustment mechanism is located outside the negative stiffness mechanism, and the output end of the angle adjustment mechanism is connected to the negative stiffness mechanism. The upper end of the central shaft extends from the top of the negative stiffness mechanism, passes through the upper guide mechanism, and is connected to the bottom of the load platform.

[0008] According to the above scheme, the negative stiffness mechanism includes an inner tile-shaped permanent magnet, an outer tile-shaped permanent magnet, two sets of inner annular permanent magnets, two sets of outer annular permanent magnets, and a magnet shell; The inner and outer tile-shaped permanent magnets are coaxially arranged. The inner tile-shaped permanent magnet and its upper and lower inner ring permanent magnets are assembled on the central shaft. The upper and lower ends of the inner ring permanent magnets are respectively pressed by fixing rings. The outer ring permanent magnet and the outer tile-shaped permanent magnet are coaxially arranged inside the magnet shell. The two outer ring permanent magnets are respectively located on the upper and lower sides of the outer tile-shaped permanent magnet. The lower end of the magnet shell is rotatably connected to the upper end of the vibration isolation box outside the positive stiffness mechanism. The output end of the angle adjustment mechanism is connected to the input end of the magnet shell. The angle adjustment mechanism drives the magnet shell to rotate. The outer tile-shaped permanent magnet and the outer ring permanent magnet located inside the magnet shell rotate synchronously relative to the inner tile-shaped permanent magnet and the inner ring permanent magnet.

[0009] According to the above scheme, the inner tile-shaped permanent magnet and the outer tile-shaped permanent magnet have the same structure but different specifications. Both are magnet assemblies and are magnetized radially. The magnet assembly is composed of an even number of tile-shaped magnetic blocks arranged circumferentially.

[0010] According to the above scheme, in the inner tile-shaped permanent magnet: the upper and lower end faces of each tile-shaped magnetic block are pressed against the inner annular permanent magnet assembled on the central shaft, and move axially with the central shaft; the magnetization directions of two adjacent tile-shaped magnetic blocks are opposite; In the outer layer of tile-shaped magnetic blocks: the upper end face of each tile-shaped magnetic block is pressed and attached to the lower end face of the upper outer ring permanent magnet, the lower end face of each tile-shaped magnetic block is pressed and attached to the upper end face of the lower outer ring permanent magnet, and the exterior of each tile-shaped magnetic block is pressed and fixed to the outer shell of the magnet; the magnetization directions of two adjacent tile-shaped magnetic blocks are opposite.

[0011] According to the above scheme, the angle adjustment mechanism includes a worm and a worm wheel. The worm is arranged vertically and meshes with the worm wheel. The worm wheel is fixed to the outer periphery of the magnet shell. When the worm rotates, it drives the worm wheel to rotate, which in turn drives the magnet shell and its inner outer tile-shaped permanent magnet and outer ring permanent magnet to rotate relative to the inner tile-shaped permanent magnet and inner ring permanent magnet.

[0012] According to the above scheme, the guiding mechanism is a linear bearing, and the central shaft is adapted to the inner ring of the linear bearing.

[0013] According to the above scheme, the vibration isolation box includes an upper box, a middle box, and a lower box connected in sequence; the guide mechanism located at the top is installed in the upper box; the worm gear of the negative stiffness mechanism and the angle adjustment mechanism is located in the middle box, the worm of the angle adjustment mechanism is located outside the middle box, and the middle box has a window for the transmission connection between the worm and the worm wheel; the magnet shell is rotatably connected to the upper end of the lower box, and the magnet shell rotates relative to the lower box.

[0014] According to the above scheme, the positive stiffness mechanism includes a linear helical spring; the linear helical spring is sleeved outside the central shaft, the upper end of the linear helical spring contacts the fixed ring at the lower part of the inner annular permanent magnet, and the lower end of the linear helical spring contacts the upper port of the base.

[0015] The present invention also employs a vibration isolation method, which is as follows: S1. Testing and Calibration: Test the magnetic force-displacement curves of the negative stiffness mechanism under different rotation angles, match the positive stiffness springs with different negative stiffness, and complete the initial parameter calibration. S2. Based on the actual load, drive the negative stiffness mechanism to rotate through the angle adjustment mechanism, adjust the negative stiffness, and confirm that the negative stiffness value cancels out the positive stiffness of the positive stiffness mechanism, so that the system reaches a near-zero stiffness state. S3. Load adaptation and vibration isolation: Place the load to be isolated stably on the load platform. The central axis, under the action of the load's gravity, will cause the inner tile-shaped permanent magnet and the inner ring permanent magnet to move vertically downward. At the same time, the fixed ring at the bottom of the inner ring permanent magnet will squeeze the positive stiffness mechanism, so that the positive stiffness mechanism bears the load. If the load changes, the negative stiffness adjustment process in step S2 needs to be repeated to change the negative stiffness value, so as to ensure that the negative stiffness and positive stiffness are always matched, and to achieve quasi-zero stiffness adaptation under different loads.

[0016] According to the above scheme, the specific process of S2 is as follows: S201, Load detection: Obtain the actual load on the load platform, determine the required target negative stiffness value, and the rotation angle of the corresponding angle adjustment mechanism; S202, Magnet Rotation: The worm gear located outside the middle housing rotates. Since the worm gear meshes with the worm wheel fixed on the outer periphery of the magnet shell, the rotation of the worm gear drives the worm wheel to rotate synchronously, thereby driving the magnet shell to rotate around the central axis. When the magnet shell rotates, the outer tile-shaped permanent magnet and the upper and lower sets of outer annular permanent magnets encapsulated inside rotate synchronously with the magnet shell, while the inner tile-shaped permanent magnet and the inner annular permanent magnet are fixed to the central axis through the non-magnetic fixing rings on the upper and lower sides, keeping them stationary, thus realizing the relative rotation of the inner and outer layers of magnets. S203. Negative stiffness adjustment: When the inner and outer tile-shaped permanent magnets rotate relative to each other, the magnetic fields of adjacent tile-shaped magnetic blocks will change due to their opposite magnetization directions, thus changing the gradient of the vertical magnetic force with displacement, i.e., the negative stiffness value. Based on the preset target negative stiffness value, the rotation angle of the worm gear is continuously fine-tuned until the negative stiffness of the negative stiffness mechanism reaches the target value. S204. After adjustment, confirm that the negative stiffness value cancels out the positive stiffness of the positive stiffness mechanism, and the system reaches a near-zero stiffness state.

[0017] The beneficial effects of this invention are as follows: 1. This invention proposes a quasi-zero stiffness vibration isolator with adjustable negative stiffness. The overall structure is simple, easy to assemble and maintain, effectively reducing manufacturing and usage costs. The isolator has a wide range of negative stiffness adjustment; the angle adjustment mechanism can directly drive the relative rotation of the permanent magnets inside the negative stiffness mechanism, achieving continuous adjustment of the negative stiffness. Combined with a replaceable positive stiffness mechanism, it achieves coordinated matching of positive and negative stiffness, adapting to different load masses, allowing the isolator to be adjusted to or near the ideal quasi-zero stiffness state, thus exhibiting wide adaptability. Furthermore, this invention ensures the coaxiality of all components through upper and lower guide mechanisms, resulting in strong structural stability, high vibration isolation accuracy, and a balance between practicality and reliability.

[0018] 2. The adjustment method of this invention is simple and reliable. It adopts a purely mechanical rotary adjustment, which does not require an external power supply or a complex control system. The structure is robust and suitable for industrial and underwater environments with high reliability requirements.

[0019] 3. This invention has a wide adjustment range and good continuity. It adopts a specially magnetized tile-shaped magnet array, which has a large range of rotation angle and negative stiffness value variation, and a large adjustment range (simulation results show that the adjustable range of negative stiffness of the four-tile structure can reach more than 38% of the peak stiffness), and can achieve continuous and fine adjustment.

[0020] 4. The present invention features a decoupled design for positive and negative stiffness. The negative stiffness is adjusted by a magnetic mechanism, while the positive stiffness is adjusted by replacing the spring. The two adjustments are relatively independent, which greatly expands the load adaptability range of the vibration isolator and simplifies the design process.

[0021] 5. The load-bearing capacity of this invention is adjustable. By replacing the positive stiffness springs with different stiffnesses, the overall load-bearing capacity of the system can be changed while adjusting the negative stiffness matching, making one device suitable for vibration isolation needs of equipment of various weights. The system's performance is even better if adjustable positive stiffness springs are used. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of Example 1.

[0023] Figure 2 This is a cross-sectional schematic diagram of Example 1.

[0024] Figure 3 This is a schematic diagram of the negative stiffness mechanism in Example 1.

[0025] Figure 4 This is a schematic diagram of the assembly of the inner and outer tile-shaped permanent magnets in Example 1.

[0026] Figure 5 This is a schematic diagram of the magnetization direction of the inner and outer tile-shaped permanent magnets in the negative stiffness mechanism of Example 1.

[0027] Figure 6 This is a schematic diagram showing the magnetization direction of the inner and outer annular permanent magnets in Example 1.

[0028] Figure 7 A family of magnetic force-displacement curves for an eight-watt rotary adjustable magnetic negative stiffness mechanism (corresponding to different rotation angles).

[0029] Figure 8 A family of magnetic force-displacement curves for a four-watt rotary adjustable magnetic negative stiffness mechanism (corresponding to different rotation angles).

[0030] The components are as follows: 1. Upper housing; 2. Middle housing; 3. Base; 4. Load platform; 5. Central shaft; 6. Guide mechanism; 7. Fixing ring; 8. Positive stiffness mechanism; 9. Negative stiffness mechanism; 10. Magnet shell; 11. Worm gear; 12. Lower housing; 13. Inner tile-shaped permanent magnet; 14. Outer ring-shaped permanent magnet; 15. Outer tile-shaped permanent magnet; 16. Inner magnetic base; 17. Inner ring-shaped permanent magnet; 18. Worm gear; 19. Outer magnetic base. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] In the description of the embodiments of this application, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0034] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0035] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, the term "a plurality of" indicates two or more.

[0036] like Figure 1 and Figure 2 The quasi-zero stiffness vibration isolator shown is specifically an adjustable negative stiffness quasi-zero stiffness vibration isolator, including a base 3, a guide mechanism 6, a central shaft 5, a negative stiffness mechanism 9, a positive stiffness mechanism 8, a vibration isolation box, an angle adjustment mechanism, and a load platform 4. The base 3 is arranged horizontally; the lower end of the central shaft 5 is installed in the base 3 through the lower guide mechanism 6; The positive stiffness mechanism 8 and the negative stiffness mechanism 9 are assembled on the central shaft 5 from bottom to top and can move axially along the central shaft 5; the positive stiffness mechanism 8 is located inside the vibration isolation box; the angle adjustment mechanism is located outside the negative stiffness mechanism 9, and the output end of the angle adjustment mechanism is connected to the negative stiffness mechanism 9. The upper end of the central shaft 5 extends from the top of the negative stiffness mechanism 9, passes through the upper guide mechanism 6, and is connected to the bottom of the load platform 4.

[0037] In this invention, the base 3 is horizontally arranged, serving as the mounting foundation for the entire vibration isolator and providing stable support for all components. Two sets of guide mechanisms 6 are respectively located at the lower and upper parts of the central shaft 5. The lower end of the central shaft 5 is mounted at the center of the base 3 via the lower guide mechanism 6, ensuring the coaxiality of the central shaft 5 and providing precise guidance for the assembly and movement of subsequent components. The angle adjustment mechanism is located outside the negative stiffness mechanism 9, facilitating adjustment by operators and preventing interference with other components inside the housing during operation. The output end of the angle adjustment mechanism is directly connected to the negative stiffness mechanism 9, precisely transmitting rotational power to drive the negative stiffness mechanism 9 to rotate, changing its negative stiffness to adapt to different load scenarios and achieve near-zero stiffness vibration isolation. After the upper end of the central shaft 5 is connected to the upper guide mechanism 6, it is fixedly connected to the bottom of the load platform 4, allowing the load platform 4 to move vertically synchronously with the central shaft 5, thereby achieving effective vibration isolation of the load.

[0038] Preferably, such as Figure 3 and Figure 4 As shown, the negative stiffness mechanism 9 includes an inner tile-shaped permanent magnet 13, an outer tile-shaped permanent magnet 15, two sets of inner annular permanent magnets 17, two sets of outer annular permanent magnets 14, and a magnet shell 10. The inner conical permanent magnet 13 and the outer conical permanent magnet 15 are coaxially arranged; the inner conical permanent magnet 13 and the two inner annular permanent magnets 17 on its upper and lower sides are all mounted on the central shaft 5, and the two inner annular permanent magnets 17 are respectively positioned by two fixing rings 7 on the central shaft 5; the outer annular permanent magnet 14 and the outer conical permanent magnet 15 are coaxially arranged inside the magnet housing 10; the two outer annular permanent magnets 14 are respectively located on the upper and lower sides of the outer conical permanent magnet 15; the lower end of the magnet housing 10 is rotatably connected to the upper end of the vibration isolation box outside the positive stiffness mechanism 8; The output end of the angle adjustment mechanism is connected to the input end of the magnet housing 10. The angle adjustment mechanism drives the magnet housing 10 to rotate. The outer tile-shaped permanent magnet 15 and the outer ring permanent magnet 14 located inside the magnet housing 10 rotate synchronously relative to the inner tile-shaped permanent magnet 13 and the inner ring permanent magnet 17.

[0039] Preferably, such as Figure 4 and Figure 5As shown, both the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15 are magnet assemblies, and are radially magnetized. The magnet assembly is composed of an even number of tile-shaped magnetic blocks arranged circumferentially. The number of tile-shaped magnetic blocks in the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15 is the same. In the inner tile-shaped permanent magnet 13, each tile-shaped magnetic block is installed on the inner magnetic base 16, and the upper and lower end faces of each tile-shaped magnetic block are respectively pressed against the inner annular permanent magnet 17 assembled on the central shaft 5 (the two inner annular permanent magnets 17 are respectively fixed to the central shaft 5 by the fixing rings 7 on the upper and lower sides, and the fixing rings 7 are non-magnetic structures), and can move axially with the central shaft 5. The inner circumferential surface of each tile-shaped magnetic block is in close contact with the central shaft 5, and the magnetization directions of two adjacent tile-shaped magnetic blocks are opposite. In the outer layer of tile-shaped magnetic blocks: each tile-shaped magnetic block is installed inside the outer magnetic base 19 (the outer magnetic base 19 and the magnet base are assembled to form the magnet shell 10, and the outer annular permanent magnet 14 is assembled inside the magnet base). The upper end face of each tile-shaped magnetic block is pressed against the lower end face of the upper outer annular permanent magnet 14, and the lower end face of each tile-shaped magnetic block is pressed against the upper end face of the lower outer annular permanent magnet 14. The exterior of each tile-shaped magnetic block is pressed and fixed to the magnet shell 10. The magnetization directions of two adjacent tile-shaped magnetic blocks are opposite.

[0040] In this invention, such as Figure 6 As shown, each annular permanent magnet is axially magnetized, and the magnetization directions of the two inner annular permanent magnets 17 are opposite, as are the magnetization directions of the two outer annular permanent magnets 14. The magnetization directions of the inner annular permanent magnets 17 located at the upper (or lower) part and the outer annular permanent magnets 14 are the same. The magnetization direction of the inner and outer annular permanent magnets at the upper part is downward, and the magnetization direction of the inner and outer annular permanent magnets at the lower part is upward. Furthermore, the axial height of each magnet is consistent, which can provide a larger magnetic force.

[0041] Preferably, the angle adjustment mechanism includes a worm gear 11 and a worm wheel 18. The worm gear 11 is arranged vertically and meshes with the worm wheel 18. The worm wheel 18 is fixed to the outer periphery of the magnet housing 10. When the worm gear 11 rotates, it drives the worm wheel 18 to rotate, which in turn drives the magnet housing 10 and its internal outer conical permanent magnet 15 and outer annular permanent magnet 14 to rotate relative to the inner conical permanent magnet 13 and inner annular permanent magnet 17. This changes the spatial distribution of the magnetic field lines and continuously and predictably changes the gradient of the vertical magnetic force with displacement, i.e., the negative stiffness value.

[0042] Preferably, the guide mechanism 6 is a linear bearing, and the central shaft 5 is adapted to the inner ring of the linear bearing.

[0043] In this invention, the vibration isolation housing includes an upper housing 1, a middle housing 2, and a lower housing 12 connected in sequence. A guide mechanism 6 located at the top is installed inside the upper housing 1. The negative stiffness mechanism 9 and the worm gear 18 of the angle adjustment mechanism are located inside the middle housing 2, while the worm 11 of the angle adjustment mechanism is located outside the middle housing 2. The middle housing 2 has a window for the transmission connection between the worm 11 and the worm gear 18. The magnet housing 10 is rotatably connected to the upper end of the lower housing 12, and the magnet housing 10 can rotate relative to the lower housing 12.

[0044] Preferably, the positive stiffness mechanism 8 includes a linear helical spring. For example... Figure 2 As shown, the linear helical spring is sleeved outside the central shaft 5. The upper end of the linear helical spring contacts the fixing ring 7 at the lower part of the inner annular permanent magnet 17 (the fixing ring 7 has a spring groove for connection and fixation). The linear helical spring is installed in the lower housing 12, and the lower end of the linear helical spring contacts the upper port of the base 3. The upper end of the base 3 is connected to the lower housing 12 (which can be threaded).

[0045] In this invention, when the central shaft 5 moves vertically downward, the fixed ring 7 moves downward and presses against the linear helical spring, which has a certain preload.

[0046] Example 1 This embodiment relates to a quasi-zero stiffness vibration isolator, including an isolation housing, and a negative stiffness mechanism 9, a positive stiffness mechanism 8, a rotation angle adjustment mechanism, and a guide mechanism 6 installed inside the isolation housing. The isolation housing includes an upper housing 1, a middle housing 2, and a lower housing 12; the upper housing 1, the middle housing 2, and the lower housing 12 of the isolation housing are fixedly connected by bolts. The guide mechanism 6 is a cylindrical linear bearing, and there are two sets, located at the upper and lower parts of the central shaft 5, respectively. The outer circumference of the upper linear bearing is assembled to the upper housing 1, and the outer circumference of the lower linear bearing is assembled to the base 3. The upper end of the central shaft 5 is connected to the load platform 4, and the lower part of the central shaft 5 passes through the upper guide mechanism 6, the negative stiffness mechanism 9, and the positive stiffness mechanism 8 in sequence before connecting to the lower guide mechanism 6. The negative stiffness mechanism 9 includes an inner conical permanent magnet 13 coaxially arranged, two sets of inner annular permanent magnets 17 located on the upper and lower sides of the inner conical permanent magnet 13, an outer conical permanent magnet 15, and two sets of outer annular permanent magnets 14 located on the upper and lower sides of the outer conical permanent magnet 15. The outer conical permanent magnets 15 and the outer annular permanent magnets 14 are both installed inside the magnet housing 10. The inner conical permanent magnets 13 and the inner annular permanent magnets 17 are fixed to a set position on the central shaft 5 by a fixing ring 7 (each conical magnetic block of the inner conical permanent magnet 13 is installed inside the inner magnetic base 16). Each conical magnetic block of the outer conical permanent magnet 15 is installed inside the outer magnetic base 19, and the outer annular permanent magnets 14 are assembled into the corresponding magnet base. The magnet base and the outer magnetic base 19 are pressed together to form the magnet housing 10. The positive stiffness mechanism 8 includes a linear helical spring, which is installed inside the lower housing 12, and the lower end of the linear helical spring is in contact with (or can be connected to) the upper port of the base 3. The upper end of the base 3 is connected to the lower housing 12 (can be threaded).

[0047] In this embodiment, a worm gear 18 is installed on the outer peripheral surface of the magnet shell 10. The worm gear 18 cooperates with the external worm 11 to drive the magnet shell 10 and its internal outer tile-shaped permanent magnet 15 and outer annular permanent magnet 14 to rotate, while the inner tile-shaped permanent magnet 13 and inner annular permanent magnet 17 do not rotate, thereby realizing the change of the relative angle between the inner and outer layers of magnets and realizing the adjustment of the negative stiffness.

[0048] In this embodiment, a 0.1mm gap is left between the magnet outer shell 10 and the intermediate box 2. This design facilitates the rotation of the magnet outer shell 10 relative to the intermediate box 2. The bottom of the magnet outer shell 10 protrudes with a cylindrical tube that is 2mm wide and 3mm high, and is embedded and fitted with the lower box 12 to facilitate the rotation of the magnet outer shell 10.

[0049] In this embodiment, the guide mechanism 6 is installed inside the upper housing 1 and the base 3, which can ensure the coaxiality of each magnet, each housing and the central shaft 5, ensure installation accuracy and reduce frictional damping.

[0050] The negative stiffness mechanism 9 employs two layers of annular permanent magnets and one layer of tile-shaped permanent magnets, arranged vertically and coaxially. For example... Figure 3 and Figure 4 As shown, two inner annular permanent magnets 17 and inner tile-shaped permanent magnets 13 are fixedly connected to the central shaft 5 via two fixing rings 7. As the central shaft 5 moves vertically, the outer annular permanent magnet 14 and outer tile-shaped permanent magnets 15 are fixed inside the magnet housing 10 (each tile-shaped magnetic block of the outer tile-shaped permanent magnet 15 is installed inside the outer magnetic base 19). The rotation angle of the magnet housing 10 is adjusted by a rotation angle adjustment mechanism. Each annular permanent magnet is axially magnetized, and each tile-shaped permanent magnet is radially radiatively magnetized, with the magnetization direction as shown... Figure 4 As shown.

[0051] The core of the negative stiffness mechanism 9 is as follows Figures 3-5 As shown. This embodiment uses a three-layer arrangement of permanent magnets, where the middle layer is a radially magnetized tile-shaped magnet (including an inner tile-shaped permanent magnet 13 and an outer tile-shaped permanent magnet 15 arranged coaxially). The inner and outer tile-shaped magnets are assembled using a "tile-shaped magnet assembly". Each tile-shaped permanent magnet consists of 8 (or 4) identical tile-shaped magnetic blocks evenly distributed circumferentially, encapsulated by an inner annular permanent magnet 17 and a fixing ring 7. The key innovation is that the magnetization direction of these 8 tile-shaped magnetic blocks is set such that the radial magnetization directions of two adjacent tile-shaped magnetic blocks are opposite (see...). Figure 4 The inner and outer tile-shaped permanent magnets are rotated at an angle by an angle adjustment mechanism, thereby adjusting the magnitude of the negative stiffness. The relative rotation of the inner and outer permanent magnets changes the spatial distribution of the magnetic field lines, thus continuously and predictably altering the gradient of the vertical magnetic force with displacement, i.e., the negative stiffness value.

[0052] In this embodiment, the radial assembly gap between the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15 is 4mm; the axial height of each magnet is 5mm; the maximum vertical stroke of the central shaft 5 is 4mm; the overall inner diameter of the inner ring permanent magnet 17 and the inner tile-shaped permanent magnet 13 is 6mm (assembled with the central shaft 5), and the overall outer diameter of both is 20mm; the overall inner diameter of the outer ring permanent magnet 14 and the outer tile-shaped permanent magnet 15 is 24mm, and the overall outer diameter of both is 48mm.

[0053] In this embodiment, the linear bearing, central shaft 5, retaining ring 7, bolts and nuts, and other components and structures are all made of non-magnetic or weakly magnetic materials, such as 304 stainless steel.

[0054] Example 2 This embodiment relates to a vibration isolation method, which is based on the quasi-zero stiffness vibration isolator described above. Specifically, a vibration isolation method is as follows: S1. Testing and Calibration: Test the magnetic force-displacement curves of the negative stiffness mechanism 9 under different rotation angles, match the positive stiffness springs with different negative stiffness, and complete the initial parameter calibration.

[0055] In this embodiment, the magnetic force-displacement curve family of the negative stiffness mechanism 9 under different rotation angles is tested by experiments to determine the correspondence between the rotation angle and the negative stiffness value; based on the test results, a suitable positive stiffness mechanism 8 is matched for different negative stiffness values ​​to complete the initial parameter calibration, ensuring that the subsequent negative stiffness adjustment can accurately match the positive stiffness and achieve a quasi-zero stiffness state.

[0056] S2. Based on the actual load, the negative stiffness mechanism 9 is rotated through the angle adjustment mechanism to adjust the negative stiffness.

[0057] In this embodiment, the specific process of S2 is as follows: S201, Load detection: Obtain the actual load on the load platform 4, and determine the required target negative stiffness value and the rotation angle of the corresponding angle adjustment mechanism based on the parameters calibrated in the early stage.

[0058] S202, Magnet Rotation: Rotate the worm gear 11 (input end of the angle adjustment mechanism) located outside the intermediate housing 2. Since the worm gear 11 meshes with the worm wheel 18 fixed on the outer periphery of the magnet housing 10, the rotation of the worm gear 11 drives the worm wheel 18 to rotate synchronously, thereby driving the magnet housing 10 to rotate around the central axis 5. When the magnet housing 10 rotates, the outer tile-shaped permanent magnet 15 and the upper and lower sets of outer annular permanent magnets 14 encapsulated inside rotate synchronously with the magnet housing 10, while the inner tile-shaped permanent magnet 13 and the inner annular permanent magnet 17 are fixed to the central axis 5 through the non-magnetic fixing rings 7 on the upper and lower sides, keeping them stationary, thus realizing the relative rotation of the inner and outer layers of magnets.

[0059] S203, Negative stiffness adjustment: When the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15 rotate relative to each other, the spatial distribution of magnetic lines of force will change because the magnetization directions of adjacent tile-shaped magnetic blocks are opposite. This will continuously and predictably change the gradient of vertical magnetic force with displacement, i.e., the negative stiffness value. According to the preset target negative stiffness value, the rotation angle of the worm gear 11 is continuously finely adjusted until the negative stiffness of the negative stiffness mechanism 9 reaches the target value. S204. After adjustment, confirm that the negative stiffness value cancels out the positive stiffness of the positive stiffness mechanism 8, and the system reaches a near-zero stiffness state.

[0060] S3, Load adaptation and vibration isolation.

[0061] In this invention, the specific method for load adaptation is as follows: The load to be isolated is placed stably on the load platform 4. The central shaft 5, under the action of the load's gravity, will drive the inner tile-shaped permanent magnet 13 and the inner ring permanent magnet 17 (fixed to the central shaft 5 by the upper and lower non-magnetic fixed rings 7) to move vertically downward along the upper and lower sets of linear bearings (guide mechanism 6). At the same time, the fixed ring 7 at the lower part of the inner ring permanent magnet 17 will squeeze the linear helical spring (positive stiffness mechanism 8), causing the linear helical spring to be further compressed to bear the load. If the load changes, the negative stiffness adjustment process in step S2 needs to be repeated to change the negative stiffness value, ensuring that the negative stiffness and positive stiffness are always accurately matched, achieving quasi-zero stiffness adaptation under different loads, and achieving the effect of "one machine for multiple uses".

[0062] In this invention, the specific method of vibration isolation is as follows: when external vibration occurs, the vibration is first transmitted to the base 3, and the base 3 transmits the vibration to the lower guide mechanism 6, and then to the central shaft 5; under the constraint and guidance of the upper and lower guide mechanisms 6, the central shaft 5 reciprocates vertically with the vibration, and at the same time drives the inner tile-shaped permanent magnet 13 and the inner ring permanent magnet 17 to move vertically synchronously; at this time, the quasi-zero stiffness system (the negative stiffness of the negative stiffness mechanism 9 cancels out the positive stiffness of the linear helical spring) has a very small resistance to external vibration, and the vibration is difficult to be transmitted to the load platform 4 through the central shaft 5; at the same time, the use of linear bearings as guide mechanisms 6 can effectively reduce the frictional damping during the movement of the central shaft 5 and avoid the amplification of load vibration.

[0063] In this embodiment, as Figure 7 and Figure 8 The figure shows a family of finite element simulation curves for the negative stiffness mechanism 9. As can be seen from the figure, with the change of rotation angle (assuming an initial rotation angle of 0 degrees and a rotation angle of 10 degrees), the relative positions of the tile-shaped magnetic blocks of the outer tile-shaped permanent magnet 15 and the tile-shaped magnetic blocks of the inner tile-shaped permanent magnet 13 are as follows: Figure 5 As shown, the slope (stiffness) of the magnetic force-displacement curve varies linearly over a large range. Figure 7 The simulation results for the three-layer eight-watt magnet structure (the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15 are each composed of 8 tile-shaped magnetic blocks) show that, as can be seen from the figure, at the equilibrium position (i.e., zero point) ±1mm, the maximum negative stiffness of the entire negative stiffness mechanism 9 is 52N / mm, the minimum negative stiffness is 39N / mm, the adjustable stiffness is 13N / mm, and the adjustable range of the system stiffness is about 25% of the maximum negative stiffness. Figure 8The simulation results for the three-layer, four-watt magnet structure (both the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15 are composed of four tile-shaped magnetic blocks) show that at the equilibrium position (i.e., zero point) ±1mm, the maximum negative stiffness of the structure is 55N / mm, the minimum negative stiffness is 34N / mm, and the adjustable stiffness is 21N / mm. The adjustable range of the system stiffness is approximately 38.2% of the maximum negative stiffness. It is evident that the lower the wattage of the inner tile-shaped permanent magnet 13 and the outer tile-shaped permanent magnet 15, the larger the adjustable range of the magnetic negative stiffness.

[0064] In this invention, by testing the magnetic force-displacement curves of the negative stiffness mechanism 9 corresponding to different rotation angles, suitable positive stiffness springs are matched for different negative stiffnesses at different rotation angles. In actual load conditions, the positive stiffness spring is matched by rotating the worm gear 11 to the corresponding angle according to the load size, thus achieving multiple uses in one machine.

[0065] In this invention, the negative stiffness of the negative stiffness mechanism 9 can be calculated based on the Biot-Savart law and the formula for calculating the axial magnetic force of the outer ring permanent magnet 14. By superimposing the magnetic forces from different magnetization methods (axial magnetization of the outer ring permanent magnet 14 and radial magnetization of the tile-shaped magnet), the total magnetic force and total negative stiffness of the magnet can be obtained. The Biot-Savart law describes the magnetic field generated by a current element at any point in space: (1); in, It is the source current, measured in amperes (A). It is a tiny line element of the source current; It is the distance from the current element to the point where the excitation magnetic field is generated, in meters (m). is the unit vector pointing from the current element to the point where the excitation magnetic field is generated; Magnetic flux density, in tons (T). It is the permeability in vacuum, and its value is 4π × 10⁻⁶. 7 H / m.

[0066] For an outer ring permanent magnet 14 with uniform magnetization along the axial direction, the equivalent current is distributed only on the inner and outer surfaces of the magnet. The formula for calculating the axial magnetic force of a magnet with uniform magnetization both inside and outside the axial direction is as follows: (2); in, , These represent the magnetic polarization intensities of the inner and outer magnets, respectively, in tons (T). , These are the half-heights of the inner and outer magnets, respectively, in meters (m). It is the distance between the selected area elements, in meters; It is a vector between the selected infinitesimal elements. , These are the radii corresponding to the selected infinitesimal element, in meters (m). , The selected infinitesimal element and x The angle between the positive directions of the axis, in degrees.

[0067] The magnetic force calculation method is similar for other magnetization methods. By superposition, the magnetic force and magnetic negative stiffness of the magnet can be calculated. The total negative stiffness of the entire negative stiffness mechanism 9 is obtained by superposition calculation.

[0068] This invention, through its innovative adjustable magnetic negative stiffness structural design, is suitable for high-precision vibration isolation applications with varying loads or requiring multiple functions in one machine.

[0069] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0070] Finally, it should be noted that the above are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A quasi-zero stiffness vibration isolator with adjustable negative stiffness, characterized in that, It includes a base, guide mechanism, central shaft, negative stiffness mechanism, positive stiffness mechanism, vibration isolation box, angle adjustment mechanism, and load platform; The base is arranged horizontally; the lower end of the central shaft is installed in the base through a lower guide mechanism; The positive stiffness mechanism and the negative stiffness mechanism are assembled on the central shaft from bottom to top and can move axially along the central shaft; the positive stiffness mechanism is located inside the vibration isolation box; the angle adjustment mechanism is located outside the negative stiffness mechanism, and the output end of the angle adjustment mechanism is connected to the negative stiffness mechanism. The upper end of the central shaft extends from the top of the negative stiffness mechanism, passes through the upper guide mechanism, and is connected to the bottom of the load platform.

2. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in claim 1, characterized in that, The negative stiffness mechanism includes an inner tile-shaped permanent magnet, an outer tile-shaped permanent magnet, two sets of inner annular permanent magnets, two sets of outer annular permanent magnets, and a magnet shell; The inner and outer tile-shaped permanent magnets are coaxially arranged. The inner tile-shaped permanent magnet and its upper and lower inner ring permanent magnets are assembled on the central shaft. The upper and lower ends of the inner ring permanent magnets are respectively pressed by fixing rings. The outer ring permanent magnet and the outer tile-shaped permanent magnet are coaxially arranged inside the magnet shell. The two outer ring permanent magnets are respectively located on the upper and lower sides of the outer tile-shaped permanent magnet. The lower end of the magnet shell is rotatably connected to the upper end of the vibration isolation box outside the positive stiffness mechanism. The output end of the angle adjustment mechanism is connected to the input end of the magnet shell. The angle adjustment mechanism drives the magnet shell to rotate. The outer tile-shaped permanent magnet and the outer ring permanent magnet located inside the magnet shell rotate synchronously relative to the inner tile-shaped permanent magnet and the inner ring permanent magnet.

3. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in claim 2, characterized in that, Both the inner and outer tile-shaped permanent magnets are magnet assemblies and are magnetized radially; the magnet assembly is composed of an even number of tile-shaped magnetic blocks arranged circumferentially.

4. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in claim 3, characterized in that, In the inner tile-shaped permanent magnet: the upper and lower end faces of each tile-shaped magnetic block are pressed against the inner annular permanent magnet assembled on the central shaft, and move axially with the central shaft; the magnetization directions of two adjacent tile-shaped magnetic blocks are opposite; In the outer layer of tile-shaped magnetic blocks: the upper end face of each tile-shaped magnetic block is pressed and attached to the lower end face of the upper outer ring permanent magnet, the lower end face of each tile-shaped magnetic block is pressed and attached to the upper end face of the lower outer ring permanent magnet, and the exterior of each tile-shaped magnetic block is pressed and fixed to the outer shell of the magnet; the magnetization directions of two adjacent tile-shaped magnetic blocks are opposite.

5. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in any one of claims 4, characterized in that, The angle adjustment mechanism includes a worm and a worm wheel. The worm is arranged vertically and meshes with the worm wheel. The worm wheel is fixed to the outer periphery of the magnet shell. When the worm rotates, it drives the worm wheel to rotate, which in turn drives the magnet shell and its inner outer tile-shaped permanent magnet and outer ring-shaped permanent magnet to rotate relative to the inner tile-shaped permanent magnet and inner ring-shaped permanent magnet.

6. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in claim 5, characterized in that, The guiding mechanism is a linear bearing, and the central shaft is adapted to the inner ring of the linear bearing.

7. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in claim 6, characterized in that, The vibration isolation box includes an upper box, a middle box, and a lower box connected in sequence; a guide mechanism located at the top is installed in the upper box; the worm gear of the negative stiffness mechanism and the angle adjustment mechanism is located in the middle box, and the worm of the angle adjustment mechanism is located outside the middle box; the middle box has a window for the transmission connection between the worm and the worm gear; the magnet shell is rotatably connected to the upper end of the lower box, and the magnet shell rotates relative to the lower box.

8. The adjustable negative stiffness quasi-zero stiffness vibration isolator as described in claim 7, characterized in that, The positive stiffness mechanism includes a linear helical spring; the linear helical spring is sleeved outside the central shaft, the upper end of the linear helical spring contacts the fixed ring at the lower part of the inner annular permanent magnet, and the lower end of the linear helical spring contacts the upper port of the base.

9. A vibration isolation method, the method being implemented based on the quasi-zero stiffness vibration isolator as described in claim 8, characterized in that, The method is as follows: S1. Testing and Calibration: Test the magnetic force-displacement curves of the negative stiffness mechanism under different rotation angles, match the positive stiffness springs with different negative stiffness, and complete the initial parameter calibration. S2. Based on the actual load, drive the negative stiffness mechanism to rotate through the angle adjustment mechanism, adjust the negative stiffness, and confirm that the negative stiffness value cancels out the positive stiffness of the positive stiffness mechanism, so that the system reaches a near-zero stiffness state. S3. Load adaptation and vibration isolation: Place the load to be isolated stably on the load platform. The central axis, under the action of the load's gravity, will cause the inner tile-shaped permanent magnet and the inner ring permanent magnet to move vertically downward. At the same time, the fixed ring at the bottom of the inner ring permanent magnet will squeeze the positive stiffness mechanism, so that the positive stiffness mechanism bears the load. If the load changes, the negative stiffness adjustment process in step S2 needs to be repeated to change the negative stiffness value, so as to ensure that the negative stiffness and positive stiffness are always matched, and to achieve quasi-zero stiffness adaptation under different loads.

10. The vibration isolation method as described in claim 9, characterized in that, The specific process of S2 is as follows: S201, Load detection: Obtain the actual load on the load platform, determine the required target negative stiffness value, and the rotation angle of the corresponding angle adjustment mechanism; S202, Magnet Rotation: The worm gear located outside the middle housing rotates. Since the worm gear meshes with the worm wheel fixed on the outer periphery of the magnet shell, the rotation of the worm gear drives the worm wheel to rotate synchronously, thereby driving the magnet shell to rotate around the central axis. When the magnet shell rotates, the outer tile-shaped permanent magnet and the upper and lower sets of outer annular permanent magnets encapsulated inside rotate synchronously with the magnet shell, while the inner tile-shaped permanent magnet and the inner annular permanent magnet are fixed to the central axis through the non-magnetic fixing rings on the upper and lower sides, keeping them stationary, thus realizing the relative rotation of the inner and outer layers of magnets. S203. Negative stiffness adjustment: When the inner and outer tile-shaped permanent magnets rotate relative to each other, the magnetic fields of adjacent tile-shaped magnetic blocks will change due to their opposite magnetization directions, thus changing the gradient of the vertical magnetic force with displacement, i.e., the negative stiffness value. Based on the preset target negative stiffness value, the rotation angle of the worm gear is continuously fine-tuned until the negative stiffness of the negative stiffness mechanism reaches the target value. S204. After adjustment, confirm that the negative stiffness value cancels out the positive stiffness of the positive stiffness mechanism, and the system reaches a near-zero stiffness state.

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