A quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping

Abstract

The application provides a quasi-zero stiffness vibration isolator with rotation inertia and eddy current damping cooperation modulation, comprising: a base; a motion conversion mechanism vertically upwardly arranged at the center of the base; an inertia rotation mechanism arranged on the motion conversion mechanism; a bearing platform fixed at the top of a lead screw; two symmetrical rhombic spring mechanisms arranged on the left and right sides of the motion conversion mechanism; two symmetrical magnetic spring assemblies arranged on the outer sides of the rhombic spring mechanisms; and two symmetrical guide mechanisms arranged on the front and back sides of the motion conversion mechanism. The linear motion of the bearing platform is converted into the rotation of the rotating assembly through the screw pair, the equivalent rotation inertia is introduced, the relative motion between the rotating magnet and the conductive part is generated, and the eddy current damping is generated; the magnetic spring and the rhombic spring are connected in parallel to form quasi-zero stiffness near the balance position, and through the synergistic effect among the rotation inertia, the eddy current damping and the quasi-zero stiffness, good vibration isolation performance is achieved.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology, specifically to a quasi-zero stiffness vibration isolator that is synergistically modulated by rotational inertia and eddy current damping. Background Technology

[0002] Quasi-zero stiffness isolators, by connecting a negative stiffness mechanism in parallel with a positive stiffness system, bring the dynamic stiffness of the system near its equilibrium position close to zero. This allows for the achievement of extremely low natural frequencies and a wide isolation frequency band while maintaining high static load-bearing capacity, and is considered an effective solution to the low-frequency vibration isolation problem of high-load-bearing equipment. However, existing quasi-zero stiffness isolation technologies still face a series of challenges in pursuing even lower frequencies and higher performance.

[0003] First, to achieve extremely low dynamic stiffness, most solutions rely on sophisticated mechanical structures (such as specific linkages, cams, or buckling beams) to generate negative stiffness. While these structures exhibit excellent quasi-zero stiffness characteristics in theoretical analysis and laboratory environments, their load-bearing capacity, reliability, durability, and resistance to eccentric loads are often limited in practical engineering applications. For example, Chinese patent CN122383813A, published in July 2026, entitled "A Quasi-Zero Stiffness Vibration Isolator," achieves quasi-zero stiffness characteristics near the equilibrium position by paralleling a positive stiffness mechanism and a negative stiffness mechanism, thereby realizing low-frequency vibration isolation. This device can improve the reliability and extend the service life of the vibration isolator, but the design of its negative stiffness mechanism presents a contradiction between load-bearing capacity and low-frequency performance.

[0004] Secondly, parameter matching and adaptive adjustment are crucial. Achieving quasi-zero stiffness characteristics highly depends on the precise matching of positive and negative stiffness; the ideal "zero stiffness point" often corresponds to a specific load or deformation. When the load changes or the system experiences a large impact, the vibration isolator may deviate from its optimal operating point, leading to increased dynamic stiffness and decreased vibration isolation performance. To address this, researchers have proposed tunable solutions. For example, Chinese patent CN122328482A, published in July 2026, entitled "An Adjustable Quasi-Zero Stiffness Vibration Isolator with Optimal Balance Position Indicator," adjusts the distance between the intermediate connecting plate and the lower connecting plate using a height adjustment mechanism. Relying on the positioning block's insertion into the positioning hole as a feedback indicator, the vibration isolator is adjusted to its optimal static balance position, preventing the negative stiffness mechanism from transmitting vertical force and achieving quasi-zero stiffness characteristics. However, such adjustments typically rely on complex mechanical structures or additional actuators, increasing system cost, complexity, and potential failure points.

[0005] While existing quasi-zero stiffness vibration isolation technologies have demonstrated advantages in statics or specific frequency bands, in practical applications, vibration isolation performance depends not only on stiffness characteristics but also on the system's damping characteristics. Appropriate damping can effectively suppress resonance peaks and improve the system's transient stability. Existing quasi-zero stiffness isolators mostly employ viscous damping or structural damping, and their damping characteristics and inertial effects are usually designed separately or non-cooperatively. In particular, there is a lack of effective solutions for how to coordinate the generation of damping with potential inertial effects (such as rotational inertia) in the system to achieve better dynamic modulation effects. Traditional designs often struggle to simultaneously achieve extremely low system natural frequencies, controllable damping characteristics, and the system's active utilization of inertial effects. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a quasi-zero stiffness vibration isolator that uses rotational inertia and eddy current damping to modulate the vibration. Through a unique motion conversion mechanism, the vertical reciprocating motion of the object to be isolated is forcibly converted into the circumferential rotational motion of an internal rotating component. This rotational motion generates a dynamic reaction force through the inertial effect of the rotating mass block and a strong eddy current damping effect through the relative motion between the rotating magnet and the fixed conductor. At the same time, the system is connected in parallel with a rhombic spring mechanism that provides negative stiffness and a magnetic spring assembly that provides positive stiffness, forming a quasi-zero stiffness system. Through the synergistic effect of rotational inertia, eddy current damping, and quasi-zero stiffness, excellent vibration isolation performance is achieved.

[0007] To achieve the above technical solution, this invention provides a quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping, comprising: a base, the main body of which is made of a rigid support material, and a conductive damping component fixedly disposed on the base to cooperate with a subsequent rotating magnet to generate an eddy current damping effect; a motion conversion mechanism installed at the center of the base and vertically upward, the motion conversion mechanism including a lead screw support fixed on the base, a lower thrust bearing fixedly mounted on the top of the lead screw support, and a support frame fixedly mounted on the base above the lead screw support, the top center of the support frame being fixedly mounted with... An upper thrust bearing is concentrically arranged with a lower thrust bearing and located directly above the lower thrust bearing. A lead screw extends longitudinally through both the upper and lower thrust bearings, with its bottom inserted into a screw support. The lead screw is restricted from circumferential rotation and can only perform linear reciprocating motion along the axial direction. An inertial rotation mechanism is mounted on a motion conversion mechanism and located between the upper and lower thrust bearings. The inertial rotation mechanism includes a rotating sleeve. A rotating nut matching the lead screw is fixedly installed on the top of the rotating sleeve. The rotating sleeve is threaded onto the lead screw via the rotating nut. The bottom of the rotating sleeve is integrally formed. A rotating support plate is provided, with vertically extending magnet mounting rods fixedly installed on both sides of the rotating support plate. A rotating magnet is fixedly installed at the bottom of each magnet mounting rod. The rotating magnets maintain a preset uniform gap with the conductive damping components on the base. The rotating nut, rotating sleeve, rotating support plate, magnet mounting rods, and rotating magnets together constitute an integrated rotating assembly. The rotating assembly achieves axial limiting through upper and lower thrust bearings and can rotate circumferentially relative to the support frame and base. A bearing platform for supporting the vibration-isolated object is fixed to the top of the lead screw via a fixed flange. The bearing platform provides vertical vibration isolation. The system performs reciprocating linear motion. Two rhomboid spring mechanisms are symmetrically installed on the left and right sides of the motion conversion mechanism. The upper and lower ends of the rhomboid spring mechanisms are connected to the bottom of the bearing platform and the top of the base, respectively, to provide negative stiffness characteristics for the vibration isolation system. Two magnetic spring assemblies are symmetrically installed on the outside of the corresponding rhomboid spring mechanisms. The upper and lower ends of the magnetic spring assemblies are connected to the bearing platform and the base, respectively, to provide positive stiffness and vertical bearing capacity for the vibration isolation system. The magnetic spring assemblies and rhomboid spring mechanisms are arranged in parallel along the vertical vibration isolation direction to form a quasi-zero stiffness system. Two guide mechanisms are symmetrically installed on the front and rear sides of the motion conversion mechanism to limit the platform's degrees of freedom and suppress sway.

[0008] In the above technical solution, this quasi-zero stiffness vibration isolator converts the vertical linear motion of the bearing platform into the precise rotational motion of the rotating nut around the lead screw through a unique motion conversion mechanism, and drives the rotating magnet to rotate at high speed near the base, establishing a complete system architecture of "motion conversion - inertial rotation - damping generation - stiffness parallel". By forcibly converting the linear vibration energy of the bearing platform into the rotational kinetic energy of the rotating component, and using this rotational kinetic energy to simultaneously excite the rotational inertial effect and the eddy current damping effect. This design can produce two key synergistic effects: (1) The equivalent mass of the rotating inertial mechanism is much greater than its physical mass, and its amplification factor is inversely proportional to the square of the lead (P) of the lead screw. This allows the system to obtain a large equivalent inertia without significantly increasing the physical mass and structural size, thereby achieving excellent vibration isolation effect in the low frequency range (far lower than traditional vibration isolators). (2) The eddy current effect generated by the rotating magnet cutting the conductive damping component provides a contactless, frictionless, highly reliable, and adjustable damping coefficient that is directly related to the rotational speed. Through the synergistic modulation of rotational inertia and eddy current damping, rotational inertia improves the equivalent dynamic mass of the system and changes the resonance and vibration isolation initiation frequency; eddy current damping mainly suppresses the resonance peak, thereby solving the problems of limited load capacity, excessively high resonance peak, and unadjustable damping of traditional quasi-zero stiffness vibration isolators.

[0009] Preferably, the bearing platform, lead screw, and guide mechanisms on both sides together constitute a moving assembly that can only move axially along the vertical vibration isolation direction. The pure linear motion of the moving assembly is converted into circumferential rotational motion of the rotating assembly through the cooperation between the lead screw and the rotating nut. During the rotation of the rotating assembly, rotational inertia and eddy current damping effects are generated simultaneously, realizing the synergistic modulation of rotational inertia and eddy current damping, which, together with the quasi-zero stiffness system, complete the vibration isolation operation. In actual operation, the precise conversion between linear and rotary motion is achieved through the lead screw and nut pair, so that rotational inertia and eddy current damping can be dynamically and synergistically excited according to the amplitude and frequency of the input vibration. This synergistic modulation enables the system to exhibit good dynamic stiffness compensation capability under different vibration conditions.

[0010] Preferably, the rhomboid spring mechanism includes a lower hinge seat and an upper hinge seat. The lower hinge seat is vertically fixed upwards to the base, and the upper hinge seat is vertically fixed downwards to the bottom of the bearing platform. The tops of the first and third links are hinged to the upper hinge seat, and the bottoms of the second and fourth links are hinged to the lower hinge seat. The bottom of the first link is hinged to the top of the second link, and the bottom of the third link is hinged to the top of the fourth link. The first, second, third, and fourth links are hinged into a rhomboid structure, and the hinge points of the first and second links and the third and fourth links are connected by tension springs. Using a rhomboid link mechanism in conjunction with tension springs to form a negative stiffness mechanism provides a stable geometry and high load-bearing capacity. Compared to traditional buckling beams or intricate link mechanisms, it offers greater manufacturing tolerance, higher reliability, and stronger resistance to eccentric loads. Furthermore, design adjustments can be made by replacing tension springs with different stiffnesses.

[0011] Preferably, the magnetic spring assembly includes an upper magnet mounting base fixed to the bottom of the bearing platform and extending vertically downwards. An upper magnet is mounted at the bottom of the upper magnet mounting base, and a lower magnet mounting base is mounted vertically upwards on the base directly below the upper magnet mounting base. A lower magnet is mounted at the top of the lower magnet mounting base, directly opposite the upper magnet. The upper and lower magnets are coaxially and repulsively arranged. The coaxially and repulsively arranged permanent magnet pair (magnetic spring assembly) provides positive stiffness and the main static load-bearing capacity. Magnetic force is a non-contact, non-linear force, and the stiffness characteristics can be designed and adjusted according to the magnet size, spacing, and magnetic pole strength, allowing the system to maintain a near-zero stiffness operating point over a wider load range and improving the adaptive capability of the vibration isolator.

[0012] Preferably, the lower magnet mounting base is configured as a height-adjustable structure, including an adjusting screw, an adjusting sleeve, and a locking nut. The adjusting sleeve is fixed to the base, the adjusting screw is vertically inserted into the adjusting sleeve and can slide vertically to adjust the height, the lower magnet is fixedly mounted on the top of the adjusting screw, and the locking nut is threaded onto the side wall of the adjusting sleeve or the adjusting screw to achieve axial locking after height adjustment. By making the lower magnet mounting base height-adjustable, the system's equilibrium position and initial negative stiffness force can be easily pre-adjusted to adapt to different load capacities, ensuring that the system operates in an optimal near-zero stiffness state.

[0013] Preferably, the guiding mechanism includes a platform linear guide rod fixed to the base and vertically upward, with a corresponding linear guide sleeve on the bearing platform. The bearing platform is mounted on the platform linear guide rod through the linear guide sleeve. The guiding mechanism, consisting of symmetrically arranged linear guide rods and linear guide sleeves, works in conjunction with the central lead screw guide to effectively restrict the bearing platform's degrees of freedom other than vertical movement. This ensures the linearity and stability of the entire system's motion, prevents platform tilting and jamming caused by off-center loading or disturbances, and makes the motion conversion of the rotary inertia mechanism more precise and reliable.

[0014] Preferably, the inner ring of the upper thrust bearing is clearance-fitted with the lead screw, and the outer ring is fixedly connected to the support frame; the inner ring of the lower thrust bearing is clearance-fitted with the lead screw, and the outer ring is fixedly connected to the screw support seat. The thrust bearing design ensures smooth rotation of the rotating assembly while bearing its axial load, resulting in a stable and reliable structure.

[0015] Preferably, the rotating nut is circumferentially fixed to the rotating sleeve by a pin / key / fastener, or the rotating nut is integrally set on the top of the rotating sleeve to ensure that the rotating nut can drive the rotating sleeve to rotate together.

[0016] Preferably, the base is made entirely of aluminum or copper plate conductor material, and the base as a conductive damping component works in conjunction with the rotating magnet to generate eddy current damping. Using the base as a conductive damping component eliminates the need for additional damping conductor installation, resulting in a highly integrated structure. Furthermore, the interaction between the large-area conductor and the rotating magnet generates a stronger eddy current damping force.

[0017] The beneficial effects of the quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping provided by this invention are as follows: (1) This invention converts the linear motion of the bearing platform into the rotation of the rotating component via a lead screw pair. While introducing equivalent rotational inertia, it causes relative motion between the rotating magnet and the conductive component, generating eddy current damping. The magnetic spring and the rhombic spring are connected in parallel to form quasi-zero stiffness near the equilibrium position. By deeply integrating and synergistically modulating the rotational inertia effect, the eddy current damping effect, and the quasi-zero stiffness characteristic, the quasi-zero stiffness characteristic significantly reduces the initial vibration isolation frequency of the system. The rotational inertia effect provides additional dynamic mass in the low-frequency range, further suppressing vibration transmission. Eddy current damping provides a stable, adjustable, and non-contact damping force, effectively smoothing the transmission rate peak of the quasi-zero stiffness system near the resonance frequency and avoiding instability phenomena such as nonlinear jumps. The synergistic effect of the three effects makes the system more robust to load changes and external excitations, and is particularly suitable for bearing precision equipment and isolating low-frequency and micro-vibrations under complex working conditions.

[0018] (2) The present invention converts the vertical linear vibration of the bearing platform into the high-speed rotation of the inertial rotation mechanism through the "motion conversion mechanism", converts linear kinetic energy into rotational kinetic energy, significantly increases the equivalent inertia of the system, introduces a considerable "inertial capacity" effect into the system without significantly increasing the static load, effectively reduces the resonance frequency of the system, and broadens the lower limit of the vibration isolation frequency band.

[0019] (3) In this invention, the rotating magnet rotates at high speed on the upper surface of the conductor base, cutting magnetic field lines and generating a strong eddy current damping force that is proportional to the rotation speed. This damping force has the characteristics of being non-contact, frictionless, and highly reliable, and can efficiently dissipate a wide spectrum of vibration energy from low-frequency large amplitude to high-frequency small amplitude, especially with excellent suppression effect on resonance peaks and transient impacts.

[0020] (4) The quasi-zero stiffness mechanism (positive and negative stiffness in parallel) composed of a magnetic spring assembly and a rhombic spring mechanism in this invention ensures that the system has near-zero dynamic stiffness near the equilibrium position, achieving an extremely low natural frequency, while providing high static support stiffness through magnetic repulsion. The three work together to optimize stiffness, inertia and damping from three dimensions, comprehensively solving the contradiction between high load-bearing capacity, ultra-low frequency vibration isolation and wide-frequency high damping. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural assembly diagram of the present invention.

[0022] Figure 2 This is a front view of the assembly structure of the motion conversion mechanism and the inertial rotation mechanism in this invention.

[0023] Figure 3 This is an exploded view of the assembly structure of the motion conversion mechanism and the inertial rotation mechanism in this invention.

[0024] Figure 4 This is a three-dimensional assembly structure diagram of the rhomboid spring mechanism and the magnetic spring assembly in this invention.

[0025] In the diagram: 1. Motion conversion mechanism; 11. Lead screw; 12. Support frame; 13. Upper thrust bearing; 14. Lower thrust bearing; 15. Screw support seat; 2. Inertial rotation mechanism; 21. Rotating nut; 22. Pin; 23. Rotating sleeve; 24. Rotating support plate; 25. Magnet mounting rod; 26. Rotating magnet; 3. Diamond spring mechanism; 31. Upper hinge seat; 32. First connecting rod; 33. Second connecting rod; 34. Third connecting rod; 35. Tension spring; 36. Fourth connecting rod; 37. Lower hinge seat; 4. Bearing platform; 5. Magnetic spring assembly; 51. Upper magnet mounting seat; 52. Upper magnet; 53. Lower magnet; 54. Lower magnet mounting seat; 6. Base; 7. Platform linear guide rod; 8. Linear guide sleeve; 9. Fixed flange. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0027] Example 1: A quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping.

[0028] Reference Figures 1 to 4 As shown, a quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping specifically includes: A square or circular base 6 serves as the basic mounting platform for the entire device. The base 6 is made of copper plate. The base is made of copper plate with high electrical conductivity, which can maximize the intensity of the eddy current induced in the rotating magnet 26, thereby obtaining the maximum eddy current damping force and optimizing the damping performance.

[0029] A motion conversion mechanism 1 is vertically mounted upwards at the center of the base 6. The core of the motion conversion mechanism 1 is a lead screw support 15, which is bolted to the center of the base 6. A lower thrust bearing 14 is mounted on the top of the lead screw support 15. On the base 6, directly above the lead screw support 15, a U-shaped support frame 12 is mounted. An upper thrust bearing 13 is mounted at the center of the top of the support frame 12, and the axes of the upper thrust bearing 13 and the lower thrust bearing 14 are strictly aligned. A high-precision lead screw 11 passes through the upper thrust bearing 13, through the central cavity, and then through the lower thrust bearing 14. Its bottom end is inserted into the guide hole inside the lead screw support 15. The inner ring of the upper thrust bearing 13 is clearance-fitted with the lead screw 11, and the outer ring is fixedly connected to the support frame 12. The inner ring of the lower thrust bearing 14 is clearance-fitted with the lead screw 11, and the outer ring is fixedly connected to the lead screw support 15. The support platform 4 is located at the top of the entire vibration isolator and is rigidly connected to the top of the lead screw 11 via a fixed flange 9. The support platform 4 is used to place precision equipment that needs vibration isolation. When external vibration acts on the base 6 or the equipment itself causes disturbance, the support platform 4 will drive the lead screw 11 to make vertical vibration displacement together.

[0030] Two sets of guiding mechanisms are symmetrically installed on the front and rear sides of the motion conversion mechanism 1. Each guiding mechanism includes a platform linear guide rod 7 vertically fixed to the base, and a linear guide sleeve 8 fixed or embedded in the bearing platform 4. The linear guide sleeve 8 and the platform linear guide rod 7 are precisely slidably engaged. These two sets of guiding mechanisms, together with the central lead screw 11, strictly constrain the bearing platform 4 to only perform vertical translational motion. In actual operation, the lead screw 11 is constrained by the upper thrust bearing 13, the lower thrust bearing 14, and its own insertion section, and under the restriction of the bearing platform 4 and the guiding mechanisms, it can only perform vertical linear reciprocating motion, and cannot rotate circumferentially.

[0031] The inertial rotation mechanism 2 is mounted on the motion conversion mechanism 1 and is located between the upper thrust bearing 13 and the lower thrust bearing 14. The inertial rotation mechanism 2 mainly includes a rotating sleeve 23, and a rotating nut 21 is circumferentially fixed to the rotating sleeve 23 by a pin 22. The rotating nut 21 is precisely fitted with the lead screw 11. A rotating support plate 24 is integrally provided at the bottom of the rotating sleeve 23. On the left and right sides of the rotating support plate 24, which are symmetrical about the axis of the lead screw 11, a magnet mounting rod 25 is vertically installed downwards on each side. A rotating magnet 26 (high-strength permanent magnet) is fixedly installed at the bottom end of each magnet mounting rod 25. The bottom surface of the rotating magnet 26 maintains a uniform gap of about 1-3mm with the upper surface of the aluminum or copper base 6.

[0032] Two sets of rhombic spring mechanisms 3 are symmetrically arranged on the left and right sides of the motion conversion mechanism 1. Each set of rhombic spring mechanisms 3 includes: a lower hinge seat 37 fixed on the base 6 and an upper hinge seat 31 fixed on the bottom of the bearing platform 4. Each hinge seat is provided with a hinge hole. The tops of the first connecting rod 32 and the third connecting rod 34 are hinged to the upper hinge seat 31, and the bottoms of the second connecting rod 33 and the fourth connecting rod 36 are hinged to the lower hinge seat 37. The bottom of the first connecting rod 32 is hinged to the top of the second connecting rod 33, and the bottom of the third connecting rod 34 is hinged to the top of the fourth connecting rod 36. The four connecting rods thus form a foldable rhombic frame. A tension spring 35 with a certain pre-tension force is connected between the hinge point of the first connecting rod 32 and the second connecting rod 33, and between the hinge point of the third connecting rod 34 and the fourth connecting rod 36. When the support platform 4 moves up and down, the rhomboid frame will open or close, and the tension spring 35 will generate a horizontal restoring force. The vertical component of this force exhibits negative stiffness characteristics.

[0033] On the outer side of each set of rhomboid spring mechanisms 3 (one on each side), magnetic spring assemblies 5 are arranged. Each magnetic spring assembly 5 includes: an upper magnet mounting base 51 extending downwards from the bottom of the support platform 4, with an upper magnet 52 fixed to its bottom; and a lower magnet mounting base 54 mounted upwards at a corresponding position on the base 6, with a lower magnet 53 fixed to its top. Both the upper magnet 52 and the lower magnet 53 are cylindrical or square permanent magnets, arranged with like poles facing each other (NN or SS), thus generating a mutually repulsive magnetic force, providing the system with primary positive stiffness support and static load-bearing capacity.

[0034] The working principle of this invention is as follows: The vibration isolation object is placed on the bearing platform 4. The weight of the vibration isolation object is transmitted to the lead screw 11 through the bearing platform 4 and the fixed flange 9, causing it to tend to move downwards. This downward force is mainly borne by the magnetic repulsion (positive stiffness) of the magnetic spring assemblies 5 on both sides; on the other hand, it pushes the lead screw 11 to translate downwards. Since the lead screw 11 cannot rotate, its downward linear motion, through the lead screw 11 and the rotating nut 21, inevitably forces the rotating nut 21 to rotate. The rotation of the rotating nut 21 drives the entire rotating assembly (rotating sleeve 23, rotating support plate 24, magnet mounting rod 25, rotating magnet 26) to rotate at high speed around the axis. This process realizes the first conversion and modulation of vibration energy, that is, the kinetic energy of linear vibration is converted into the rotational kinetic energy of the rotating assembly. The rotating nut 21, rotating sleeve 23, rotating support plate 24, and rotating magnet 26 constitute a rotating body with a moment of inertia J, which requires torque to start. Under the preload designed in the system, the rotating body remains stationary, and the system reaches static equilibrium. At this point, the rhomboid spring mechanisms 3 on both sides are at a specific opening angle. The tension spring 35 inside provides an inward horizontal force, which manifests as an upward "negative stiffness" force in the vertical direction, partially offsetting the positive stiffness force of the magnetic spring. By carefully designing the stiffness and preload of the tension spring 35, as well as the spacing between the upper magnet 52 and the lower magnet 53, the total dynamic stiffness (the sum of positive and negative stiffness) of the system at the equilibrium position can approach zero, achieving a quasi-zero stiffness state.

[0035] When the base 6 is subjected to an upward vibration impact from the outside (assuming simple harmonic motion), it will cause the bearing platform 4 and its load to generate a downward relative motion with respect to the base 6 (or it can be understood as the bearing platform 4 having an upward absolute acceleration relative to inertial space). This motion tendency is again acted on the rotating nut 21 through the lead screw 11. During the dynamic process, the rotating body composed of the rotating nut 21, rotating sleeve 23, and rotating magnet 26 will overcome static friction and begin to rotate. According to Newton's second law and the screw drive relationship, the relationship between the angular acceleration β of the rotating body and the linear acceleration a of the bearing platform (and load) is a = (P / (2π))•β, where P is the lead screw. The dynamic equation of the rotating body is T=J•β, where T is the driving torque of the screw acting on the nut. The driving torque T and the equivalent inertial force F acting on the bearing platform are related. iner The relationship can be linked through factors such as screw efficiency. Ultimately, the equivalent inertial mass reflected in the motion equations of the load-bearing platform is m. eff = (4π 2 •J) / P 2 Since the lead P is typically a small number (e.g., 5 mm), its square is very small, making the equivalent mass m... eff It is much larger than the sum of the actual mass of the rotating body and the load mass. This requires the external excitation to push a very large mass, thus producing a very strong vibration isolation effect in the low-frequency domain and significantly reducing the effective natural frequency of the system.

[0036] During the aforementioned dynamic process, the rotating magnets 26 on both sides of the rotating support plate 24 sweep across the copper base 6 at high speed. The changing magnetic field induces eddy currents in the base 6, and the magnetic field generated by these eddy currents interacts with the magnetic field of the rotating magnets 26, producing a resistance torque that consistently opposes the movement of the rotating magnets 26. This resistance torque, through the conversion between the lead screw 11 and the rotating nut 21, manifests as an equivalent linear damping force on the bearing platform 4 that hinders its vibration. This process achieves a second conversion and modulation of vibration energy, namely, the rotational kinetic energy is dissipated as heat energy by the eddy current damping effect, providing the system with stable, adjustable, and frictionless non-contact damping. Near the resonant frequency, when the response speed (i.e., the rotational speed) is large, the eddy current damping effect is significantly enhanced, effectively dissipating vibration energy, smoothing out resonance peaks, and preventing excessive impact.

[0037] Throughout the vibration cycle, the magnetic spring assembly 5 (positive stiffness) and the rhomboid spring mechanism 3 (negative stiffness) work together to ensure that the system maintains a very low dynamic stiffness near the equilibrium position. When the load changes, the user can manually adjust the height of the lower magnet 53 in the magnetic spring assembly 5 to change the magnitude of the positive stiffness, thereby rematching the negative stiffness. This allows the system to maintain quasi-zero stiffness characteristics at the new equilibrium position and has the ability to adapt to different loads.

[0038] This invention, through an ingenious integrated design, organically combines linear-rotational motion conversion, rotational inertia utilization, eddy current damping generation, and parallel positive and negative stiffness, achieving synergistic modulation of the triple physical effects of rotational inertia, electromagnetic damping, and quasi-zero stiffness, thereby achieving excellent and stable low-frequency and micro-vibration isolation effects.

[0039] Experimental verification and technical effects To further verify the invention, a prototype was manufactured according to the structure of the invention. The prototype used a 1.7 kg vibration isolation mass and underwent a unidirectional upsampling frequency sweep test in the range of 2–17 Hz, with a base displacement of 1 mm. By using three progressive configurations while maintaining other consistent conditions, the functions of the quasi-zero stiffness mechanism, the rotating inertia unit, and the eddy current damping unit were verified respectively. The test results are shown in Table 1: Table 1 Test results of prototypes with different functions

[0040] Compared to the RMS-QZSI test prototype, the RMS-RI-QZSI test prototype, after introducing rotational inertia, saw its resonant frequency decrease from 3.45 Hz to 2.54 Hz, a reduction of approximately 26.4%, and its initial isolation frequency decrease from 4.15 Hz to 3.34 Hz. With the further addition of eddy current damping, the RMS-RIED-QZSI test prototype saw its resonant peak decrease from 9.13 dB to 7.01 dB, while the resonant frequency only changed from 2.54 Hz to 2.51 Hz. The complete RMS-RIED-QZSI test prototype system showed an 8.39 dB reduction in resonant peak compared to the RMS-QZSI system, corresponding to a reduction of approximately 61.9% in linear peak transmissibility and approximately 29.2% in the initial isolation frequency.

[0041] The above experimental data show that rotational inertia has a more significant effect on the shift of resonance and initial isolation frequencies, and eddy current damping has a more significant effect on suppressing resonance peaks. This further verifies the rationality of the functional division of this invention according to "frequency adjustment - peak suppression".

[0042] Example 2: A quasi-zero stiffness vibration isolator modulated by rotational inertia and eddy current damping.

[0043] The difference from Embodiment 1 is that the base 1 is made of steel and does not directly serve as a conductor. Instead, two independent copper or aluminum plates are embedded and fixed on the base 1, corresponding to the positions directly below the two rotating magnets 26 on the left and right sides, respectively, as conductive damping components. Other structures and working principles are the same as in Embodiment 1. This solution is suitable for applications requiring a base with higher strength or made of different materials.

[0044] Example 3: A quasi-zero stiffness vibration isolator modulated by rotational inertia and eddy current damping.

[0045] The difference from Embodiment 1 is that the lower magnet mounting base 54 is configured as a height-adjustable structure, specifically including an adjusting screw, an adjusting sleeve, and a locking nut. The adjusting sleeve is fixed to the base 4, the adjusting screw is vertically inserted into the adjusting sleeve 4 and can slide vertically to adjust the height, the lower magnet 53 is fixedly mounted on the top of the adjusting screw, and the locking nut is threaded onto the side wall of the adjusting sleeve or the adjusting screw to achieve axial locking after height adjustment. By making the lower magnet mounting base 54 height-adjustable, the system's equilibrium position and initial negative stiffness force can be easily pre-adjusted to adapt to different load capacities and ensure that the system operates in an optimal quasi-zero stiffness state. Other structures and working principles are the same as in Embodiment 1.

[0046] Example 4: A quasi-zero stiffness vibration isolator modulated by rotational inertia and eddy current damping.

[0047] The difference from Embodiment 1 is that the rotating nut 23 is integrally formed on the top of the rotating sleeve 21, which can improve the connection strength between the rotating nut 23 and the rotating sleeve 21. Other structures and working principles are the same as in Embodiment 1.

[0048] The above description is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in the embodiments and drawings. Therefore, any equivalent or modified embodiments made without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping, characterized in that... include: The base is made of a rigid support material. A conductive damping component is fixedly installed on the base to cooperate with the subsequent rotating magnet and generate an eddy current damping effect in cooperation with the rotating magnet. A motion conversion mechanism is installed at the center of a base and vertically upward. The motion conversion mechanism includes a lead screw support fixed on the base. A lower thrust bearing is fixedly mounted on the top of the lead screw support. A support frame is fixedly mounted on the base above the lead screw support. An upper thrust bearing is fixedly mounted at the center of the top of the support frame. The upper thrust bearing and the lower thrust bearing are concentrically arranged and located directly above the lower thrust bearing. A lead screw passes through the upper thrust bearing and the lower thrust bearing longitudinally, and the bottom of the lead screw is inserted into the lead screw support. The lead screw is restricted from circumferential rotation and can only perform linear reciprocating motion along the axial direction. An inertial rotation mechanism is installed on a motion conversion mechanism and located between an upper thrust bearing and a lower thrust bearing. The inertial rotation mechanism includes a rotating sleeve. A rotating nut matching a lead screw is fixedly installed on the top of the rotating sleeve. The rotating sleeve is threaded onto the lead screw via the rotating nut. A rotating support plate is integrally formed at the bottom of the rotating sleeve. Vertically downward magnet mounting rods are fixedly installed on both sides of the rotating support plate. A rotating magnet is fixedly installed at the bottom of each magnet mounting rod. The rotating magnets maintain a preset uniform gap with the conductive damping components on the base and are relatively spaced apart. The rotating nut, rotating sleeve, rotating support plate, magnet mounting rods, and rotating magnets together constitute an integral rotating assembly. The rotating assembly is axially limited by the upper and lower thrust bearings and can rotate circumferentially relative to the support frame and the base. A bearing platform, which is fixed to the top of the lead screw by a fixed flange, is used to support the vibration isolation object. The bearing platform reciprocates linearly along the vertical vibration isolation direction. Two symmetrically mounted diamond-shaped spring mechanisms are installed on the left and right sides of the motion conversion mechanism. The upper and lower ends of the diamond-shaped spring mechanisms are respectively connected to the bottom of the bearing platform and the top of the base, and are used to provide negative stiffness characteristics for the vibration isolation system. Two magnetic spring assemblies are symmetrically installed on the outside of the corresponding rhomboid spring mechanism. The upper and lower ends of the magnetic spring assembly are respectively connected to the bearing platform and the base, which are used to provide positive stiffness and vertical bearing capacity for the vibration isolation system. The magnetic spring assembly and the rhomboid spring mechanism are arranged in parallel along the vertical vibration isolation direction to form a quasi-zero stiffness system. Two symmetrical guide mechanisms are installed on the front and rear sides of the motion conversion mechanism to limit the platform's degrees of freedom and suppress sway.

2. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The bearing platform, lead screw, and guide mechanisms on both sides together constitute a moving component that can only move axially along the vertical vibration isolation direction. The pure linear motion of the moving component is converted into the circumferential rotational motion of the rotating component through the cooperation between the lead screw and the rotating nut. During the rotation of the rotating component, rotational inertia effect and eddy current damping effect are generated simultaneously, realizing the coordinated modulation of rotational inertia and eddy current damping, and jointly completing the vibration isolation operation with the quasi-zero stiffness system.

3. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The rhomboid spring mechanism includes a lower hinge seat and an upper hinge seat. The lower hinge seat is fixed vertically upward on the base, and the upper hinge seat is fixed vertically downward on the bottom of the bearing platform. The tops of the first and third connecting rods are hinged to the upper hinge seat, and the bottoms of the second and fourth connecting rods are hinged to the lower hinge seat. The bottom of the first connecting rod is hinged to the top of the second connecting rod, and the bottom of the third connecting rod is hinged to the top of the fourth connecting rod. The first, second, third, and fourth connecting rods are hinged into a rhomboid structure, and the hinge points of the first and second connecting rods and the third and fourth connecting rods are connected by a tension spring.

4. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The magnetic spring assembly includes an upper magnet mounting base fixed to the bottom of the support platform and extending vertically downward. An upper magnet is mounted on the bottom of the upper magnet mounting base. A lower magnet mounting base is mounted vertically upward on the base directly below the upper magnet mounting base. A lower magnet is mounted on the top of the lower magnet mounting base, facing the upper magnet. The upper magnet and the lower magnet are coaxially arranged and repulsing each other.

5. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 4, characterized in that, The lower magnet mounting base is configured as a height-adjustable structure, including an adjusting screw, an adjusting sleeve, and a locking nut. The adjusting sleeve is fixed on the base, the adjusting screw is vertically inserted into the adjusting sleeve and can slide vertically to adjust the height, the lower magnet is fixedly installed on the top of the adjusting screw, and the locking nut is threaded onto the side wall of the adjusting sleeve or the adjusting screw to achieve axial locking after the height adjustment is completed.

6. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The guiding mechanism includes a platform linear guide rod fixed on the base and vertically upward, and a corresponding linear guide sleeve is provided on the bearing platform. The bearing platform is installed through the linear guide sleeve on the platform linear guide rod.

7. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The inner ring of the upper thrust bearing is clearance-fitted with the lead screw, and the outer ring is fixedly connected to the support frame. The inner ring of the lower thrust bearing is clearance-fitted with the lead screw, and the outer ring is fixedly connected to the screw support seat.

8. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The rotating nut is circumferentially fixed to the rotating sleeve by a pin / key / fastener, or the rotating nut is integrally set on the top of the rotating sleeve.

9. The quasi-zero stiffness vibration isolator with synergistic modulation of rotational inertia and eddy current damping as described in claim 1, characterized in that, The base is made of aluminum or copper plate conductor material. The base acts as a conductive damping component and works with the rotating magnet to generate eddy current damping.

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