A quasi-zero stiffness vibration isolation device based on a rotatable leaf spring to generate negative stiffness

Abstract

A kind of quasi-zero stiffness vibration isolation device based on negative stiffness generated by rotatable leaf spring, quasi-zero stiffness vibration isolation device includes positive stiffness component, negative stiffness component and height adjustment pad;Positive stiffness component, negative stiffness component and height adjustment pad are all installed in outer sleeve, and the bottom surface of positive stiffness component extends from the bottom of outer sleeve, beyond the bottom surface of outer sleeve, forms height difference on level;Negative stiffness component is located above positive stiffness component, and upper end surface extends the upper end surface of outer sleeve, outer sleeve is installed in floating plate, and moves up and down with floating plate together;The negative stiffness component is the negative stiffness component formed by rotatable leaf spring combination, and negative stiffness is generated by the change of rotatable leaf spring.The rotation or movement of rotatable leaf spring negative stiffness component in the process of vibration isolation forms matching negative stiffness, so that good quasi-zero stiffness low-frequency vibration isolation performance is obtained, and the vibration isolation efficiency of floating bed system is improved;It has the characteristics of simple structure, high reliability and long service life.

Description

Technical Field

[0001] This invention relates to a method for achieving negative stiffness in vibration isolation, and more particularly to a quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness. This quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness can truly realize the engineering application of negative stiffness, achieving a quasi-zero stiffness vibration isolation effect together with positive stiffness. It is easy to manufacture and has high reliability. It belongs to the field of vibration reduction and isolation technology for urban rail transit. Background Technology

[0002] With the development of modern technology, analysis of various environments has revealed that vibration is a major cause of many accidents. For example, hypersonic vehicles endure severe vibration environments during flight; high levels of vibration can cause equipment malfunctions or even catastrophic consequences. NASA's statistical analysis of space launches in the 1970s showed that vibration was one of the most significant factors leading to flight failures. Therefore, the requirements for vibration isolation in various environments are becoming increasingly stringent. Scientists have also discovered that isolating equipment from dynamic excitation using vibration isolators is one of the simplest and most effective methods for vibration-environment-adaptive design to ensure equipment performance under vibration conditions.

[0003] According to vibration isolation theory, the larger the participating mass and the smaller the support stiffness of a vibration isolation system, the lower its natural frequency and the better the vibration isolation effect. However, traditional vibration isolators generally cannot resolve the contradiction between low-frequency vibration isolation and installation stability. For example, the steel spring floating slab vibration-damping track, which currently has the best vibration isolation effect in urban rail transit vibration reduction measures, achieves good vibration isolation due to its large mass and low stiffness "mass-spring plus damping" vibration isolation system. However, in actual engineering design, limitations imposed by tunnel space, construction costs, and train operation safety make it quite difficult to improve the vibration isolation effect of the system by increasing mass and reducing stiffness.

[0004] Research has revealed that the main influencing factor on the vibration isolation frequency band of a vibration isolation system is the system's stiffness. Reducing the system's stiffness lowers its natural frequency, extending the isolation frequency band to lower and ultra-low frequencies, thus achieving a wider isolation frequency band and isolating the harmful effects of vibration. To reduce system stiffness, quasi-zero stiffness vibration isolation technology is employed. By achieving higher static stiffness and lower dynamic stiffness, it achieves excellent low-frequency vibration isolation performance while maintaining its load-bearing capacity. Therefore, quasi-zero stiffness vibration isolation technology has become a research hotspot for scholars both domestically and internationally in recent years. Consequently, the design and application of quasi-zero stiffness isolators have become a goal pursued in the field of vibration reduction / isolation technology. Quasi-zero stiffness vibration isolation is a passive vibration isolation method that introduces negative stiffness elements and reduces the overall stiffness of the system through quasi-zero stiffness mechanisms. Quasi-zero stiffness vibration isolation systems are characterized by simple structure, low energy consumption, low cost, and high reliability, making them the most important method for future vibration control.

[0005] On the other hand, in recent years, my country's urban rail transit has developed rapidly, leading to increasingly prominent environmental vibration and noise problems. With rising public awareness of environmental protection and strengthened national environmental protection efforts, especially the recent regulations on environmental noise pollution prevention and control, environmental vibration and noise control in urban rail transit construction has become a crucial issue. To address the problem of existing floating slab track isolation devices with steel springs or rubber springs failing to isolate low-frequency or ultra-low-frequency vibrations, to reduce the initial isolation frequency of the track slab, to increase the isolation frequency range, and to improve isolation efficiency, it is also necessary to develop a quasi-zero stiffness floating slab track isolation device with low dynamic stiffness.

[0006] However, in terms of current applications of near-zero stiffness, it has not yet been used in urban rail transit vibration reduction measures. At present, the best vibration isolation effect of urban rail transit vibration reduction measures is the steel spring floating slab vibration isolation track. Because the steel spring floating slab vibration isolation track adopts a "mass-spring plus damping" vibration isolation system with large mass and low stiffness, it has a good vibration isolation effect. However, in practical engineering applications, limitations imposed by tunnel space, construction costs, and train operation safety make it difficult to improve the vibration isolation effect of vibration isolation systems by increasing mass and reducing stiffness. Therefore, a new vibration isolation system with engineering application value is needed for vibration reduction. Analysis shows that using quasi-zero stiffness isolation is the best solution. Although some researchers have begun to study the application of quasi-zero stiffness in urban rail transit, the proposed quasi-zero stiffness vibration isolation devices currently available are difficult to meet the needs of actual urban rail transit. In particular, the negative stiffness generation devices in quasi-zero stiffness systems are difficult to meet the requirements of engineering applications, and some proposed methods for generating negative stiffness do not have engineering application value. Therefore, proposing a quasi-zero stiffness vibration isolation device with engineering application value is of great significance.

[0007] However, the main approach to achieving near-zero stiffness in engineering applications is still through parallel connection of negative stiffness components to positive stiffness systems. While there are numerous literature reports on so-called "quasi-zero stiffness vibration isolation," most of the currently available "quasi-zero stiffness" vibration isolation devices are merely research projects conducted by universities, lacking truly practical engineering applications. Among these, the following are most relevant to this application:

[0008] 1. The invention patent entitled "Quasi-zero stiffness vibration isolator floating slab track bed and its design method" (CN201810244688.6) discloses a quasi-zero stiffness vibration isolator floating slab track bed and its design method, including a floating slab and vibration isolation components disposed in the floating slab. The vibration isolation components are spaced apart along the length of the floating slab. The vibration isolation components are characterized in that the vibration isolation components include an outer sleeve cast in the floating slab and a quasi-zero stiffness vibration isolator installed in the outer sleeve. A height adjustment shim for adjusting the height of the floating slab is placed between the quasi-zero stiffness vibration isolator and the outer sleeve. The top of the outer sleeve is covered with an insulating cover plate.

[0009] 2. A utility model patent entitled "A Quasi-Zero Stiffness Vibration Isolator and Track Slab for Railway Vibration Reduction" (CN202120434799.0) describes a vibration isolator comprising a cylindrical support base and a butterfly spring. The cylindrical support base contains a rubber support, and the top of the rubber support has a lower flange bearing plate. The lower flange bearing plate has a vertically arranged connecting rod, and the connecting rod is threadedly connected to an upper flange bearing plate. The connecting rod passes through the butterfly spring, and the bottom end of the butterfly spring abuts against the top end of the cylindrical support base. The top end of the butterfly spring abuts against the bottom surface of the upper flange bearing plate.

[0010] 3. The invention patent titled "A Flexible Adjustable Quasi-Zero Stiffness Vibration Reduction Platform" (CN201510438515.4) includes a fixed platform, a moving platform, a vibration reduction component, and a thrust component. The vibration reduction component is connected to the fixed and moving platforms. The thrust component is mounted on the fixed platform and applies thrust to the moving platform; multiple thrust components are arranged around the moving platform. This vibration reduction platform can achieve quasi-zero stiffness at its static equilibrium position and nonlinear stiffness near the static equilibrium position, solving the problem of traditional linear vibration isolation systems isolating low-frequency or ultra-low-frequency vibrations. However, this invention only provides a flexible adjustable quasi-zero stiffness vibration reduction platform. Due to its large structural size, numerous components, and low integration, it is not suitable for track bed slabs.

[0011] Problems or shortcomings of existing technologies:

[0012] While these patents all involve negative stiffness elements and propose some improved technical solutions, careful analysis reveals that none of them can be truly applied in practical engineering. Among them,

[0013] Patent 1 only provides a quasi-zero stiffness vibration reduction platform that can be flexibly adjusted. Due to its large structural size, many parts, and low integration, it is not suitable for track bed slabs.

[0014] Patent 2 proposes a method to achieve negative stiffness using various types of disc springs, including large, medium and small ones. While this method is theoretically feasible, it is difficult to control the deformation of the disc springs in practical applications. In particular, when using disc springs to achieve negative stiffness, they are prone to flipping when they are close to horizontal, resulting in failure. Therefore, using disc springs to achieve negative stiffness is not advisable.

[0015] Patent 3 proposes a theoretical quasi-zero stiffness vibration isolator floating slab track bed, but the actual structure is impossible to implement, and therefore has no practical application value.

[0016] To address the problem of existing steel spring or rubber spring vibration isolators' inability to isolate low-frequency or ultra-low-frequency vibrations in floating slab track, and to reduce the initial isolation frequency of the track slab, increase the isolation frequency range, and improve isolation efficiency, it is necessary to develop a quasi-zero stiffness floating slab track vibration isolation device with low dynamic stiffness that can be applied in engineering. Furthermore, with the rapid development of urban rail transit and increased efforts to control environmental pollution, the demand for this product will continue to grow, making it worthy of serious study. Summary of the Invention

[0017] The technical problem to be solved by this invention is that existing quasi-zero stiffness devices cannot be applied to urban tunnel floating slab tracks, and existing track vibration isolation devices are difficult to isolate low-frequency or ultra-low-frequency vibrations of rail vehicles during operation. This invention provides a quasi-zero stiffness floating slab track vibration isolation device with practical engineering application value, simple structure, and mass production capability, thus solving the technical shortcomings of existing track vibration isolators, such as complex installation and difficult maintenance.

[0018] This invention is mainly achieved through the following technical solution: a quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness. The quasi-zero stiffness vibration isolation device includes a positive stiffness component, a negative stiffness component, and a height adjustment plate. The positive stiffness component, negative stiffness component, and height adjustment plate are all installed inside an outer sleeve, with the bottom surface of the positive stiffness component extending beyond the bottom surface of the outer sleeve, forming a horizontal height difference. The negative stiffness component is located above the positive stiffness component, with its upper end extending beyond the upper end surface of the outer sleeve. The outer sleeve is installed in a floating plate and moves up and down with the floating plate. The negative stiffness component is a negative stiffness component formed by a combination of rotatable leaf springs, generating negative stiffness through the change of the rotatable leaf springs. The negative stiffness component includes an outer bearing component, an inner bearing component, a negative stiffness mechanism, and a top cover plate. The outer bearing component is a stepped cylindrical structure with a larger upper end and a smaller lower end along the axial direction; its upper inner cavity has a stepped hole structure and an internal thread is provided near the end position; the inner bearing component, the negative stiffness mechanism, and the upper cover plate are coaxially mounted in the upper inner cavity; the outer cylinder at its lower end is provided with an external thread and forms an assembly relationship with the internal thread at the upper end of the stepped hole in the center of the upper cover bearing cylinder in the positive stiffness component; the inner bearing component is a cylindrical structure with the outer diameter of the bottom circle of the barrel being larger than the outer diameter of the barrel and forming a shoulder; the bottom of the barrel has a central circular hole and forms an assembly relationship with the top stepped shaft of the central shaft pin provided on the base plate in the positive stiffness component; the inner bearing component is coaxially mounted at the bottom of the upper inner cavity of the outer bearing component; the negative stiffness mechanism is coaxially mounted between the upper inner cavity of the outer bearing component and the cylindrical inner bearing component.

[0019] Furthermore, the outer sleeve is a cylindrical steel cylinder with a square steel plate welded to its lower end. Reinforcing steel bars for pre-embedding are welded to the middle part of the outer side of the cylinder. Support rings for bearing and lifting are welded to the inner side of the cylinder near the upper end and the top end, respectively. The outer sleeve is pre-embedded in the floating slab of the reinforced concrete track bed, and the height of the outer sleeve is consistent with the thickness of the floating slab.

[0020] Furthermore, the positive stiffness component includes a base, a cylindrical helical spring, and a top cover bearing cylinder. The base is a cylindrical structure, and the cylindrical helical spring is placed inside the base. A central shaft pin is provided on the bottom plate of the base, with its lower end firmly connected to the bottom plate and its upper end configured as a stepped shaft. The top cover bearing cylinder is installed on top of the cylindrical helical spring and serves as the upper bearing platform or support frame of the vibration isolator. The top cover bearing cylinder has a stepped through hole at its center, with an internal thread at the upper end and a tubular structure at the lower end, with a damping disc on its lower end face. The stepped through hole at the center of the top cover bearing cylinder and the central shaft pin of the base barrel are coaxially spaced.

[0021] Furthermore, a liquid damping material is placed in the gap between the base and the cylindrical helical spring. The damping disc on the lower end face of the upper cover bearing cylinder is immersed in the liquid damping material.

[0022] Furthermore, in the quasi-zero stiffness vibration isolation device, the base of the positive stiffness component is installed on the foundation ground, and the height adjustment pad is installed on the top surface of the upper cover bearing cylinder and supported on the upper end bearing support ring of the inner cavity of the outer sleeve. The height adjustment pad consists of multiple pads of varying thicknesses with through holes in the center.

[0023] Furthermore, the upper cover plate is a cylindrical disc-shaped structure with a countersunk hole on its upper end face. A nut is welded at the center of the countersunk hole, and the outer cylinder is provided with external threads, which are assembled with the internal threads provided in the upper cavity of the outer bearing component.

[0024] Furthermore, the negative stiffness mechanism comprises multiple negative stiffness unit combinations, which are vertically stacked together to form the negative stiffness mechanism. Each negative stiffness unit combination is essentially formed by multiple negative stiffness units continuously arranged circumferentially on the same plane; and the stacking of multiple negative stiffness unit combinations along a plumb line constitutes the negative stiffness mechanism. The inner diameter of the negative stiffness unit combination is clearance-fitted with the outer diameter of the inner bearing component barrel, and its inner diameter and bottom end face are respectively assembled with the outer diameter of the inner bearing component barrel and the outer edge shoulder of the barrel bottom. The outer diameter of the negative stiffness unit combination is assembled with the inner diameter of the outer bearing component's inner cavity.

[0025] Further, the negative stiffness unit includes an upper support block, an upper support rubber component, an upper support copper tile, an upper support spring sheet, a buckling leaf spring, a lower support spring sheet, a lower support copper tile, a lower support rubber component, and a lower support block. The upper support block, upper support rubber component, and upper support spring sheet are bonded and vulcanized into a single unit; the lower support spring sheet, lower support rubber component, and lower support block are also bonded and vulcanized into a single unit. The buckling leaf spring is a rectangular spring sheet with a width approximately half its length, slightly curved downwards along its length. Cylindrical surfaces are formed at both ends along its length, with a radius approximately 1.5 times the thickness of the spring sheet. The end cylindrical surfaces transition to the upper and lower surfaces along the thickness direction of the spring sheet using rounded arcs. The buckling leaf spring has an inclined angle between its length direction and the horizontal plane. The cylindrical surfaces at both ends form upper and lower articulated support surfaces, and copper tiles, i.e., upper and lower support copper tiles, are wrapped around the cylindrical surfaces at both ends.

[0026] Furthermore, the upper support spring plate is a spring plate with a width consistent with the width of the bent leaf spring, but bent into an arc-like shape along its length. The cylindrical concave surface in its middle portion forms a friction pair connection with the upper support copper plate of the bent leaf spring. The lower support spring plate is a spring plate with a width consistent with the width of the bent leaf spring, but bent into an arc-like shape along its length. The cylindrical concave surface in its middle portion forms a friction pair connection with the lower support copper plate of the bent leaf spring.

[0027] Furthermore, the upper support block is a load-bearing component that only allows vertical movement. Its lower left side is designed with an arc-shaped concave surface, which corresponds to the arc-shaped convex surface of the upper support spring plate. The gap between the arc-shaped concave surface of the upper support block and the arc-shaped convex surface of the upper support spring plate is filled with an upper support rubber component and then bonded and vulcanized together. The lower support block is a load-bearing component placed on a base platform that restricts horizontal movement. Its upper right side is designed with an arc-shaped concave surface, which corresponds to the arc-shaped convex surface of the lower support spring plate. The gap between the arc-shaped concave surface of the lower support block and the arc-shaped convex surface of the lower support spring plate is filled with a lower support rubber component and then bonded and vulcanized together.

[0028] Furthermore, the negative stiffness mechanism is composed of multiple negative stiffness units; wherein, the lower support block of the negative stiffness unit is designed as a ring to form the inner ring of the negative stiffness mechanism; the upper support block of the negative stiffness unit is designed as a ring to form the outer ring of the negative stiffness mechanism; the buckling leaf springs in the negative stiffness unit are evenly arranged along the circumferential direction to form a similar slotted disc spring, and are combined with the upper and lower support copper tiles and support spring plates, and are bonded and vulcanized together with the inner and outer rings through rubber rings to form a whole, thus forming the negative stiffness mechanism.

[0029] Furthermore, the bending leaf spring is a flat spring sheet, which is rectangular in shape. Its width is 1 / 3 to 1 / 2 of its length, and it is slightly bent downward along the middle of the length direction. At both ends of the length direction, there are cylindrical surfaces with the width direction as the axis. The radius of the cylindrical surface is about 1.3 to 1.8 times the thickness of the spring sheet. The cylindrical surface at the end is connected to the upper and lower surfaces of the spring sheet in the thickness direction by a rounded transition.

[0030] Furthermore, the length (L) of the bent leaf spring is 14-25 mm; the thickness is 0.6-1 mm; and the initial angle (A) of the bent leaf spring is between 15-25 degrees.

[0031] The working principle of the negative stiffness unit is as follows: Both the upper and lower support blocks are restricted from horizontal movement and are assembled into a whole with other elastic components through rubber bonding, vulcanization, and assembly. The lower support block is placed on the foundation platform, and when the upper support block is subjected to a vertical load, it generates a vertical displacement. Under the action of the load, the force transmission path is: upper support block → upper support rubber component → upper support spring plate → upper support copper tile → buckling leaf spring → lower support copper tile → lower support spring plate → lower support rubber component → lower support block. During this process, the rubber component undergoes elastic compression deformation, the metal spring plate undergoes elastic bending deformation, and simultaneously, the jointed connection at both ends of the buckling leaf spring rotates, causing its angle with the horizontal plane to change from large to small. This results in a decrease in the vertical component of the negative stiffness unit, i.e., the support reaction force. Under continuous loading, when the angle between the buckling leaf spring and the horizontal plane is zero, the vertical component of the negative stiffness element, i.e. the support reaction force, is also zero. As a result, the stiffness curve formed by the vertical force and displacement acting on the upper support block is a stiffness curve similar to a parabola.

[0032] The beneficial effects of this invention are as follows: By replacing the steel springs or rubber springs in the existing track bed slab with a quasi-zero stiffness vibration isolation device, the dynamic stiffness can be low or close to zero under static equilibrium conditions. This solves the problem of traditional linear vibration isolation systems isolating low-frequency or ultra-low-frequency vibrations, reduces the initial isolation frequency, increases the isolation frequency range, and improves the system's vibration isolation efficiency. At the same time, it completely preserves the load-bearing capacity and reliability of the existing floating slab vibration-damping track. Attached Figure Description

[0033] Figure 1 Schematic diagram of the construction of a quasi-zero stiffness vibration isolation device;

[0034] Figure 2 This is a schematic diagram of the axial section of the outer sleeve;

[0035] Figure 3 This is a schematic diagram of the overall assembly of the present invention;

[0036] Figure 4 This is a schematic diagram of the assembly of a positive stiffness component;

[0037] Figure 5 This is a schematic diagram of the assembly of a negative stiffness component.

[0038] Figure 6 This is a schematic diagram of a negative stiffness element mechanism.

[0039] Figure 7 This is a schematic diagram of a negative stiffness unit composite structure;

[0040] Figure 8 This is a schematic diagram of a negative stiffness element structure;

[0041] Figure 9This is a schematic diagram illustrating the vertical movement of a negative stiffness element.

[0042] Figure 10 Schematic diagram of the planar layout of a buckling leaf spring;

[0043] Figure 11 This is a schematic diagram of the axial cross-section of the upper cover plate;

[0044] Figure 12 The stiffness curve formed by the vertical force and displacement of the negative stiffness element;

[0045] In the diagram: 1—Concrete floating slab, 2—Outer sleeve, 3—Near-zero stiffness vibration isolation device, 4—Square steel plate, 5—Cylindrical steel cylinder, 6—Bearing support ring, 7—Construction support ring, 8—Positive stiffness component, 9—Height adjustment pad, 10—Negative stiffness component, 11—Base, 12—Cylindrical helical spring, 13—Upper cover bearing cylinder, 14—Central shaft pin, 15—Damping disc, 16—Outer bearing component, 17—Inner bearing component, 18—Negative stiffness mechanism, 19—Upper cover plate, 20—Negative stiffness mechanism, 21—Inner ring, 22—Outer ring, 23—Elastic mechanism combination ring, 24—Upper support block, 25—Upper support rubber component, 26—Upper support copper tile, 27—Upper support spring plate, 28—Buckling leaf spring, 29—Lower support spring plate, 30—Lower support copper tile, 31—Lower support rubber component, 32—Lower support block, 33—Nut. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments and accompanying drawings. Example 1

[0047] This embodiment is a quasi-zero stiffness vibration isolation device based on the negative stiffness generated by a rotatable leaf spring. The quasi-zero stiffness vibration isolation device includes a positive stiffness component (8), a height adjustment plate (9), and a negative stiffness component (10). The positive stiffness component (8), the height adjustment plate (9), and the negative stiffness component (10) are all installed inside the outer sleeve (2), and the bottom surface of the positive stiffness component (8) extends from the bottom of the outer sleeve (2), exceeding the bottom surface of the outer sleeve (2), forming a horizontal height difference; the negative stiffness component (10) is installed inside the outer sleeve (2). And it is located above the positive stiffness component (8); the upper end face of the negative stiffness component (10) extends out of the upper end face of the outer sleeve (2), and the negative stiffness component (10) moves together with the outer sleeve (2) as it moves up and down with the floating track bed, and generates negative stiffness in the process of moving. The resultant force formed by the positive stiffness component (8) and the upward elastic force generated by the positive stiffness component (8) remains basically constant, thereby constituting the quasi-zero stiffness vibration isolation; the negative stiffness component (10) is a rotatable leaf spring negative stiffness component, and negative stiffness is generated by the rotatable leaf spring negative stiffness component.

[0048] like Figure 1As shown: The novel floating slab track isolation device of the present invention consists of a concrete floating slab (1), an outer sleeve (2), and a quasi-zero stiffness vibration isolation device (3). Among them, the outer sleeve (2) is evenly embedded at symmetrical positions on both sides of the centerline of the rail on the concrete floating slab (1), and the quasi-zero stiffness vibration isolation device (3) is installed inside the outer sleeve (2) to support the concrete floating slab (1).

[0049] Because the quasi-zero stiffness vibration isolation device has low or near-zero dynamic stiffness in static equilibrium, it solves the problem of traditional linear vibration isolation systems isolating low-frequency or ultra-low-frequency vibrations, reduces the initial isolation frequency, increases the isolation frequency range, and improves the system's vibration isolation efficiency.

[0050] like Figure 2 As shown: The outer sleeve (2) is a cylindrical steel cylinder (5), with a square steel plate (4) welded to its lower end. A reinforcing steel bar for pre-embedding is welded to the middle part of the outer side of the cylinder. A load-bearing support ring (6) and a construction support ring (7) are welded to the inner cavity near the upper end and the top end, respectively. The outer sleeve (2) is pre-embedded in the concrete floating slab (1), and the height of the outer sleeve (2) is consistent with the thickness of the concrete floating slab (1).

[0051] like Figure 3 As shown: The quasi-zero stiffness vibration isolation device (3) is composed of a positive stiffness component (8), a height adjustment pad (9), and a negative stiffness component (10). The positive stiffness component (8) and the negative stiffness component (10) are coaxially connected in parallel and supported on the bearing support ring (6) in the outer sleeve (2) by the height adjustment pad (9). The height adjustment pad (9) consists of multiple pads of different thicknesses with through holes in the center. The static load-bearing capacity of the quasi-zero stiffness vibration isolation device (3) is mainly borne by the positive stiffness component (8), but near the static equilibrium position, because the positive stiffness component (8) and the negative stiffness component (10) are connected in parallel and simultaneously bear the impact force from the upper structure, the dynamic stiffness of the vibration isolation system is low or close to zero, thereby obtaining good low-frequency vibration isolation performance and improving the system's vibration isolation efficiency.

[0052] like Figure 3 , 4As shown: The positive stiffness component (8) includes a base (11), a cylindrical helical spring (12), and an upper cover bearing cylinder (13). The base (11) is a cylindrical structure, and the cylindrical helical spring (12) is placed inside the base (11). The base (11) has a central shaft pin (14) on the bottom plate of the barrel. The lower end of the central shaft pin (14) is firmly connected to the bottom plate, and the top end is set as a stepped shaft. The upper cover bearing cylinder (13) is installed on the top of the cylindrical helical spring and serves as the upper bearing platform of the vibration isolator. The upper cover bearing cylinder (13) has a stepped through hole at its axial center. The upper end of the through hole has an internal thread, and the lower end of the through hole is a tubular structure. The lower end face of the tubular structure has a damping disc (15). The central stepped through hole of the upper cover bearing cylinder (13) and the central shaft pin (14) of the base (11) are in a gap-type coaxial assembly relationship.

[0053] The positive stiffness component (8) is set in the concrete floating slab (1) between the track (25) and the floating slab track bed (34); wherein the base (11) is installed on the foundation ground, and the outer edge of the height adjustment pad (9) installed on the top surface of the upper cover bearing cylinder (13) is supported on the bearing support ring (6) of the inner cavity of the outer sleeve (2).

[0054] A liquid damping material is placed in the gap between the base (11) and the cylindrical helical spring (12). The damping disc (15) on the lower end face of the upper cover bearing cylinder (13) is immersed in the liquid damping material.

[0055] like Figure 3 , 4 As shown in Figure 5: The negative stiffness component (10) includes an outer bearing component (16), an inner bearing component (17), a negative stiffness mechanism (18), and an upper cover plate (19). The outer bearing component (16) is a stepped cylindrical structure with a larger upper end and a smaller lower end along the axial direction; its upper inner cavity is a stepped hole structure, and an internal thread is provided near the end position; the inner bearing component (16), the negative stiffness mechanism (18), and the upper cover plate (19) are coaxially installed in its upper inner cavity respectively; an external thread is provided on the outer cylinder at its lower end, and it forms an assembly relationship with the internal thread at the upper end of the stepped hole in the center of the upper cover bearing cylinder (13) in the positive stiffness component (8). The inner bearing component (17) is a cylindrical structure, the outer diameter of the bottom of the barrel is larger than the outer diameter of the barrel and forms a shoulder, and a central circular hole is opened at the bottom of the barrel. The central circular hole and the end face of the hole form an assembly relationship with the top stepped shaft of the central shaft pin (14) provided on the base plate (11) in the positive stiffness component (8). The inner bearing component (17) is coaxially mounted at the bottom of the upper inner cavity of the outer bearing component (16). The negative stiffness mechanism (18) is coaxially mounted between the upper inner cavity of the outer bearing component (16) and the cylindrical part of the inner bearing component (17).

[0056] The upper cover plate (19) is a cylindrical disc-shaped structure, with an external thread on its outer cylinder that is assembled with the internal thread of the upper cavity of the outer bearing component (16). The lower end face of the upper cover plate (19) is assembled with the top surface of the outer ring (22) of the negative stiffness mechanism (18).

[0057] like Figure 6 As shown: The negative stiffness mechanism (18) is composed of multiple negative stiffness units (20) stacked along the plumb line.

[0058] like Figure 5 , 6 As shown in Figure 7: The negative stiffness unit assembly (20) includes an inner ring (21), an outer ring (22), and negative stiffness units (23). The negative stiffness unit assembly (20) is equivalent to multiple negative stiffness units (23) arranged continuously along the circumferential direction on the same plane; and multiple negative stiffness unit assemblies (20) stacked along the plumb line constitute a negative stiffness mechanism (18). The inner ring (21) of the negative stiffness unit assembly (20) or the negative stiffness mechanism (18) has a clearance fit with the outer diameter of the inner bearing component (17), and the inner diameter and bottom end face of the inner ring (21) are respectively assembled with the outer diameter of the inner bearing component (17) and the outer edge shoulder of the bottom of the barrel. The outer diameter of the outer ring (22) of the negative stiffness unit assembly (20) or the negative stiffness mechanism (18) is assembled with the inner diameter of the inner cavity of the outer bearing component (16).

[0059] like Figure 8 As shown: The negative stiffness unit includes an upper support block (24), an upper support rubber component (25), an upper support copper tile (26), an upper support spring sheet (27), a buckling leaf spring (28), a lower support spring sheet (29), a lower support copper tile (30), a lower support rubber component (31), and a lower support block (32). The upper support block (24), upper support rubber component (25), and upper support spring sheet (27) are bonded and vulcanized into a single unit; the lower support spring sheet (29), lower support rubber component (31), and lower support block (32) are also bonded and vulcanized into a single unit.

[0060] The bent leaf spring (28) is a rectangular leaf spring with a width approximately half of its length (L). Preferably, its width is 1 / 3 to 1 / 2 of its length, and it is slightly bent downward along the middle of the length direction. At both ends of the length direction, there are cylindrical surfaces with the width direction as the axis. The radius of the cylindrical surfaces is approximately 1.3 to 1.8 times the thickness of the leaf spring. The cylindrical surfaces at the ends are connected to the upper and lower surfaces of the leaf spring in the thickness direction by a circular arc transition.

[0061] The bending leaf spring (28) is inclined at an angle (A) between its length direction and the horizontal plane. The cylindrical surfaces at both ends of the spring form upper and lower articulated support surfaces, and copper tiles, namely upper support copper tile (26) and lower support copper tile (30), are wrapped on the cylindrical surfaces at both ends of the spring.

[0062] Preferably, the length (L) of the bent leaf spring (28) is 14-25 mm; the thickness is 0.6-1 mm; and the initial angle (A) of the bent leaf spring is between 15-25 degrees.

[0063] The upper support spring plate (27) is a spring plate with a width consistent with the width of the bent leaf spring (28) and a bow-like shape in the length direction. The cylindrical concave surface in the middle part forms a friction pair connection with the upper support copper tile (26) of the bent leaf spring (28).

[0064] The lower support spring plate (29) is a spring plate with a width consistent with the width of the bent leaf spring (28), but bent into an arc-like shape in the length direction. The cylindrical concave surface in the middle part forms a friction pair connection with the lower support copper tile (30) of the bent leaf spring (28). The upper support block (24) is a load-bearing component that only allows up and down movement. Its lower left direction is designed as an arc-shaped concave surface, which forms a corresponding mating relationship with the arc-shaped convex surface of the upper support spring plate (27). The gap between the arc-shaped concave surface of the upper support block (24) and the arc-shaped convex surface of the upper support spring plate (27) is filled by the upper support rubber part (25) and bonded and vulcanized together as a whole.

[0065] The lower support block (32) is a load-bearing component placed on the base platform that restricts horizontal movement. Its upper right side is designed as an arc-shaped concave surface, which forms a corresponding mating relationship with the arc-shaped convex surface of the lower support spring plate (29). The gap between the arc-shaped concave surface of the lower support block (32) and the arc-shaped convex surface of the lower support spring plate (29) is filled by the lower support rubber part (31) and bonded and vulcanized together as a whole.

[0066] The working principle of the negative stiffness unit is as follows: the upper support block (24) and the lower support block (32) are both restricted from moving in the horizontal direction and are combined with the other elastic components by rubber bonding, vulcanization and assembly into a whole. The lower support block (24) is placed on the foundation platform, and when the upper support block (32) is subjected to vertical load, it will generate vertical displacement. Under the action of the load force, its force transmission path is: upper support block (24) → upper support rubber part (25) → upper support spring plate (27) → upper support copper tile (26) → buckling leaf spring (28) → lower support copper tile (30) → lower support spring plate (29) → lower support rubber part (31) → lower support block (32). Among them, the rubber part generates elastic compression deformation, the metal spring plate generates elastic buckling deformation, and at the same time, the angle (A) between the length direction of the buckling leaf spring (28) and the horizontal plane changes, that is, it changes from large to small. Under continuous loading, when the angle between the length direction of the buckling leaf spring (28) and the horizontal plane is zero, the vertical component of the negative stiffness element, i.e., the support reaction force, is also zero. Therefore, the stiffness curve formed by the vertical force and displacement acting on the upper support block (24) is a parabolic stiffness curve, as shown in the attached figure. Figure 12 As shown.

[0067] like Figure 7 , 8 As shown in Figure 9: The negative stiffness unit combination (20) is composed of multiple negative stiffness units combined on the same horizontal plane. The lower support block (32) of the negative stiffness unit is designed as a ring, which constitutes the inner ring (21) of the negative stiffness unit combination (20); the upper support block (24) of the negative stiffness unit is designed as a ring, which constitutes the outer ring (22) of the negative stiffness unit combination (20); the buckling leaf spring (28) in the negative stiffness unit is evenly arranged in the circumferential direction to form a similar slotted disc spring, and is combined with the upper and lower support copper tiles (26, 30) and the upper and lower support spring plates (27, 29). The rubber ring formed by the upper and lower rubber parts (25, 31) is bonded and vulcanized together with the inner ring (21) and the outer ring (22) to form a whole, which constitutes the negative stiffness unit combination (20).

[0068] like Figure 5 , 11 As shown: The upper cover plate (19) is a cylindrical disc-shaped structure with a countersunk hole on its upper end face. A nut (33) is welded at the center of the countersunk hole. The outer cylinder is provided with an external thread, which is in an assembly relationship with the internal thread provided in the upper inner cavity of the outer bearing component (16). The lower end face of the upper cover plate (19) is in an assembly relationship with the top surface of the outer ring (22) of the negative stiffness mechanism (18).

[0069] In summary, the beneficial effects of this invention are as follows: By replacing the steel springs or rubber springs in the existing track bed slab with a quasi-zero stiffness vibration isolation device, low or near-zero dynamic stiffness can be achieved under static equilibrium conditions. This solves the problem of traditional linear vibration isolation systems isolating low-frequency or ultra-low-frequency vibrations, reduces the initial isolation frequency, increases the isolation frequency range, and improves the system's vibration isolation efficiency. Simultaneously, it completely preserves the load-bearing capacity and reliability of existing floating slab vibration-damping tracks. Example 2

[0070] The basic principle of Embodiment 2 is the same as that of Embodiment 1, except that the structure is slightly different. It is a quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness. The quasi-zero stiffness vibration isolation device includes a positive stiffness component, a negative stiffness component, and a height adjustment plate. All three components are installed inside the outer sleeve, with the bottom surface of the positive stiffness component extending beyond the bottom of the outer sleeve, creating a horizontal height difference. The negative stiffness component is installed inside the outer sleeve and located above the positive stiffness component. The upper end of the negative stiffness component extends beyond the upper end of the outer sleeve. The outer sleeve is installed in a floating plate and moves along with it as the floating plate moves up and down, generating negative stiffness during this movement. The resultant force formed by the negative stiffness and the upward elastic force generated by the positive stiffness component remains essentially constant, thus constituting the quasi-zero stiffness vibration isolation. The negative stiffness component is a rotatable leaf spring negative stiffness component, which generates negative stiffness.

[0071] The outer sleeve, positive stiffness component, negative stiffness component, and height adjustment plate are all square in shape, forming a square quasi-zero stiffness vibration isolation device. The negative stiffness units within the negative stiffness component are arranged in a square ring above the positive stiffness component to form a negative stiffness unit combination. Multiple square negative stiffness unit combinations are then vertically combined to form a negative stiffness mechanism.

[0072] Moreover, each negative stiffness unit has only a buckling leaf spring and a rotatable node. The buckling leaf spring has ball joints at both ends. The ball joints at both ends of the buckling leaf spring are respectively hinged to the elastic support plates that are stuck in the outer and inner load-bearing components, forming rotatable nodes. As the outer and inner load-bearing components move up and down, the buckling leaf spring rotates and buckles around the two rotatable nodes, forming negative stiffness.

[0073] The other parts are the same as in Embodiment 1. This embodiment only changes the structure of the leaf spring, adopting a bent leaf spring and a rotatable ball head structure at both ends; this embodiment is the simplest way to form the negative stiffness of the rotating leaf spring, but it has high requirements for the bent leaf spring (38), and the bent leaf spring (38) needs to have a large deformation, so the manufacturing of the bent leaf spring (38) is somewhat difficult. Example 3

[0074] The structure of Embodiment 3 is the same as that of Embodiment 1, except that there are slight differences in structure. It is a quasi-zero stiffness vibration isolation device based on the negative stiffness generated by a rotatable leaf spring. The quasi-zero stiffness vibration isolation device includes a positive stiffness component, a negative stiffness component, and a height adjustment plate. The positive stiffness component, the negative stiffness component, and the height adjustment plate are all installed inside the outer sleeve, and the bottom surface of the positive stiffness component extends from the bottom of the outer sleeve, exceeding the bottom surface of the outer sleeve to form a horizontal height difference. The negative stiffness component is installed inside the outer sleeve and is located above the positive stiffness component. The upper end surface of the negative stiffness component extends from the upper end surface of the outer sleeve. The outer sleeve is installed in the floating plate and moves with the floating plate as it moves up and down, generating negative stiffness during the movement. The resultant force formed by the negative stiffness and the upward elastic force generated by the positive stiffness component remains basically constant, thereby constituting the quasi-zero stiffness vibration isolation. The negative stiffness component is a rotatable leaf spring negative stiffness component, which generates negative stiffness.

[0075] The outer sleeve, positive stiffness component, negative stiffness component, and height adjustment plate are all hexagonal in shape, forming a hexagonal quasi-zero stiffness vibration isolation device. The negative stiffness units within the negative stiffness component are arranged in a hexagonal ring above the positive stiffness component, forming a negative stiffness unit combination. Multiple hexagonal negative stiffness unit combinations are then vertically combined to form a negative stiffness mechanism.

[0076] Moreover, each negative stiffness unit is composed of a rigid leaf spring and an elastic rotatable node. The rigid leaf spring has ball joints at both ends, which are respectively hinged to elastic support plates that are locked in the outer and inner load-bearing components. The elastic support plates are then bonded to the outer and inner load-bearing components through elastic rubber layers, forming elastic rotatable nodes. As the rigid leaf spring moves up and down with the outer and inner load-bearing components, it only rotates at the hinge points of the elastic support plates without buckling deformation. Instead, it compensates for the change in length of the rigid leaf spring in the horizontal direction by compressing the rubber layers of the elastic rotatable nodes at both ends, thus changing the magnitude and direction of the force on both ends of the rigid leaf spring and forming negative stiffness.

[0077] The adjustments to other parts are the same as in Embodiment 1. This embodiment solves the adverse effects of the change in length of the leaf spring during the process of moving from an inclined to a horizontal state by setting the elastic deformation of the elastic rotatable node. Moreover, it is made of elastic rubber, and the required deformation can be achieved by adjusting the hardness and stiffness of the rubber material. It has good elastic control effect and can easily achieve variable stiffness adjustment of negative stiffness, so it will become the first choice for negative stiffness adjustment. Example 4

[0078] The structure of Embodiment 4 is the same as that of Embodiment 1, except that there are slight differences in structure. It is a quasi-zero stiffness vibration isolation device based on the negative stiffness generated by a rotatable leaf spring. The quasi-zero stiffness vibration isolation device includes a positive stiffness component, a negative stiffness component, and a height adjustment plate. The positive stiffness component, the negative stiffness component, and the height adjustment plate are all installed inside the outer sleeve, and the bottom surface of the positive stiffness component extends from the bottom of the outer sleeve, exceeding the bottom surface of the outer sleeve to form a horizontal height difference. The negative stiffness component is installed inside the outer sleeve and is located above the positive stiffness component. The upper end surface of the negative stiffness component extends from the upper end surface of the outer sleeve. The outer sleeve is installed in the floating plate and moves with the floating plate as it moves up and down, generating negative stiffness during the movement. The resultant force formed by the negative stiffness and the upward elastic force generated by the positive stiffness component remains basically constant, thereby constituting the quasi-zero stiffness vibration isolation. The negative stiffness component is a rotatable leaf spring negative stiffness component, which generates negative stiffness.

[0079] Each negative stiffness unit of the negative stiffness component is composed of a buckling leaf spring and a composite rotatable node, wherein one end of the composite rotatable node is an elastic rotatable node and the other end is a rigid rotatable node.

[0080] Furthermore, the upper support block of the negative stiffness unit is a load-bearing component that only allows up and down movement. Its lower left direction is designed as an arc-shaped concave surface, which forms a corresponding mating relationship with the arc-shaped convex surface of the upper support spring plate. The gap between the arc-shaped concave surface of the upper support block and the arc-shaped convex surface of the upper support spring plate is filled with the upper support rubber component and bonded and vulcanized together as a whole.

[0081] The lower support block of the negative stiffness unit is a load-bearing component placed on the foundation platform that restricts horizontal movement. Its upper right direction is designed as an arc-shaped concave surface, which forms a corresponding mating relationship with the arc-shaped convex surface of the lower support spring plate. The arc-shaped convex surface of the lower support spring plate is directly embedded in the arc-shaped concave surface of the lower support block, forming an elastically compressible and rotatable node at one end.

[0082] The adjustments to other parts are the same as in Embodiment 1. This embodiment simply uses a combination of a buckling leaf spring and a rotatable joint at one end. This utilizes both the buckling deformation advantage of the buckling leaf spring and the compressibility of elastic rubber. The combination of the two can reduce the difficulty caused by the high requirements of a single method for adjusting negative stiffness, as mentioned above, and better achieve the adjustment and change of negative stiffness. At the same time, the use of a rigid rotatable joint at one end of the buckling leaf spring is beneficial for processing and manufacturing, and facilitates mass production.

[0083] It should be noted that the above-listed embodiments are merely a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Furthermore, terms such as "upper," "lower," "front," "rear," and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention. Simultaneously, the structures, proportions, sizes, etc., depicted in the accompanying drawings are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0084] The beneficial effects of this invention are:

[0085] This invention replaces the steel or rubber spring vibration isolators in existing track slabs with a quasi-zero stiffness vibration isolation device. This achieves low or near-zero dynamic stiffness in a static equilibrium state, solving the problem of traditional linear vibration isolation systems when isolating low-frequency or ultra-low-frequency vibrations. It reduces the initial isolation frequency, increases the isolation frequency range, and improves the system's vibration isolation efficiency. Simultaneously, it fully retains the load-bearing capacity and reliability of existing floating slab vibration-damping tracks. Its main advantages are as follows:

[0086] 1. Replacing the steel springs or rubber springs in the existing track bed with quasi-zero stiffness vibration isolation devices can effectively eliminate noise pollution caused by low-frequency or ultra-low-frequency vibrations when rail transit vehicles pass by.

[0087] 2. The negative stiffness mechanism in the quasi-zero stiffness vibration isolation device uses a rotatable leaf spring instead of a conventional piston rod, disc spring, or linear spring. This eliminates the problem of unstable and uneven force caused by vertical force when the piston rod type negative stiffness is formed. It also solves the problem of torsional deformation when the disc spring negative stiffness is formed, preventing uneven force in various directions and torsional deformation.

[0088] 3. The negative stiffness mechanism uses a rotatable node to connect a rotatable leaf spring, allowing both ends of the leaf spring to rotate. This allows the rotatable leaf spring to adjust its air posture during operation, effectively solving the problem of jamming under vertical forces that previously relied on piston-type rod extension and retraction. By adjusting the air posture of the rotatable leaf spring through the rotation of the rotatable node to create negative stiffness, there is no jamming problem during the process. Therefore, it can truly realize the engineering application of quasi-zero stiffness vibration isolation through negative stiffness intervention.

[0089] 4. The rotatable node of the negative stiffness mechanism adopts an elastic compressible structure. When the rotatable leaf spring rotates from the inclined plane to the horizontal, the elastic layer of the rotating node can be compressed to compensate for the dimensional changes of the rotatable leaf spring in the horizontal direction, and prevent the rotatable leaf spring from becoming unstable due to excessive horizontal force.

[0090] 5. By adjusting the rotation and compression of the rotatable leaf spring through the elastic rotating node, the magnitude of the negative stiffness can be precisely adjusted, truly achieving a perfect match with the positive stiffness of the quasi-zero stiffness vibration isolation system, and truly realizing quasi-zero stiffness vibration isolation.

[0091] 6. The rotatable leaf spring adopts a buckling leaf spring structure. During operation, negative stiffness can also be formed by the directional deformation of the buckling leaf spring. In this way, the required negative stiffness can be formed by the change of the buckling rotatable leaf spring itself or by its combination with the elastic rotating node.

[0092] 7. The negative stiffness mechanism adopts a combination of multiple negative stiffness units stacked vertically, which can effectively disperse the force of the entire negative stiffness and greatly reduce the force on each negative stiffness unit. This not only makes the force on the negative stiffness unit more uniform, but also effectively improves the service life of the negative stiffness unit.

[0093] 8. This negative stiffness mechanism has a simple structure, is stable and reliable during implementation, and can accurately determine the variation law of negative stiffness, thereby finding the accurate negative stiffness and its variation law required for the quasi-zero stiffness vibration isolation of the system, and truly realizing the quasi-zero stiffness vibration isolation of the system.

Claims

1. A quasi-zero stiffness vibration isolation device based on negative stiffness generated by a rotatable leaf spring, the quasi-zero stiffness vibration isolation device comprising a positive stiffness component, a negative stiffness component and a height adjustment pad; the positive stiffness component, the negative stiffness component and the height adjustment pad are all installed in an outer sleeve, and the bottom surface of the positive stiffness component protrudes from the bottom of the outer sleeve, beyond the bottom surface of the outer sleeve, to form a height difference in the horizontal direction; characterized in that: The negative stiffness component is located above the positive stiffness component, and the upper end surface extends out of the upper end surface of the outer sleeve. The outer sleeve is installed in the floating plate and moves up and down with the floating plate. The negative stiffness component is a negative stiffness component combined by a rotatable sheet spring, and the negative stiffness is generated by the change of the rotatable sheet spring. The negative stiffness component comprises an outer bearing component, an inner bearing component, a negative stiffness mechanism and an upper cover plate. The outer bearing component is a stepped cylindrical structure with a large upper end and a small lower end. The inner cavity of the upper end is a stepped hole structure, and an internal thread is arranged near the end. The inner cavity of the upper end is coaxially installed with the inner bearing component, the negative stiffness mechanism and the upper cover plate. The outer thread is arranged on the outer cylinder of the lower end and is in assembly relationship with the internal thread of the upper end of the stepped hole of the positive stiffness component. The inner bearing component is a cylindrical structure, and the outer diameter of the bottom is larger than the outer diameter of the cylinder and forms a shaft shoulder. A central hole is opened in the bottom, and the top stepped shaft of the center shaft pin arranged on the bottom plate of the base of the positive stiffness component is in assembly relationship. The inner bearing component is coaxially installed on the bottom of the inner cavity of the outer bearing component. The negative stiffness mechanism is coaxially installed between the inner cavity of the outer bearing component and the cylinder of the inner bearing component.

2. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness according to claim 1, characterized in that: The positive stiffness component comprises a base, a cylindrical spiral spring and an upper cover bearing cylinder. The base is a cylindrical structure, and the cylindrical spiral spring is placed in the base. A center shaft pin is arranged on the center bottom plate of the base, and the lower end of the shaft pin is firmly connected with the bottom plate, and the top end is arranged as a stepped shaft. The upper cover bearing cylinder is installed at the top end of the cylindrical spiral spring and serves as an upper bearing platform or support frame of the vibration isolator. The center of the upper cover bearing cylinder is provided with a stepped through hole, the upper end of the through hole is provided with an internal thread, the lower end of the through hole is a tubular structure, and the lower end surface of the tubular structure is provided with a damping disc. The central stepped through hole of the upper cover bearing cylinder is in coaxial gap assembly relationship with the center shaft pin.

3. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness according to claim 2, characterized in that: A liquid damping material is placed in the gap between the base and the cylindrical spiral spring. The damping disc of the lower end surface of the upper cover bearing cylinder is immersed in the liquid damping material.

4. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness of claim 1, wherein: The base of the positive stiffness component is installed on the base ground, and the height adjusting pad is installed on the top surface of the upper cover bearing cylinder and supported on the bearing support ring at the upper end of the inner cavity of the outer sleeve. The height adjusting pad is a plurality of gaskets with different thicknesses and a through hole in the center.

5. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness of claim 1, wherein: The upper cover plate is a cylindrical pie structure, and a counterbore is opened in the upper end surface. A nut is welded at the center position of the counterbore, and an external thread is arranged on the outer cylinder and is in assembly relationship with the internal thread arranged in the inner cavity of the outer bearing component.

6. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness of claim 1, wherein: The negative stiffness mechanism is formed by vertically stacking a plurality of negative stiffness units to form a negative stiffness mechanism. The negative stiffness unit combination is formed by continuously arranging a plurality of negative stiffness units in the same plane in the circumferential direction. The negative stiffness unit combination is stacked in the plumb direction to form the negative stiffness mechanism. The inner diameter of the inner circle of the negative stiffness unit combination and the outer diameter of the cylinder of the inner bearing component are in clearance fit, and the inner diameter of the inner circle and the bottom end surface are in assembly relationship with the outer diameter of the cylinder of the inner bearing component and the shaft shoulder of the outer edge of the cylinder bottom, respectively. The outer diameter of the outer circle of the negative stiffness unit combination and the inner diameter of the inner cavity of the outer bearing component are in assembly relationship.

7. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness according to claim 6, characterized in that: The negative stiffness unit comprises an upper supporting block, an upper supporting rubber piece, an upper supporting copper tile, an upper supporting spring piece, a flexural leaf spring, a lower supporting spring piece, a lower supporting copper tile, a lower supporting rubber piece and a lower supporting block; the upper supporting block, the upper supporting rubber piece and the upper supporting spring piece are bonded and vulcanized into one whole; the lower supporting spring piece, the lower supporting rubber piece and the lower supporting block are bonded and vulcanized into one whole; the flexural leaf spring is provided with an inclined angle between the length direction and the horizontal plane, and the two end cylindrical surfaces form upper and lower joint supporting surfaces, and the upper supporting copper tile and the lower supporting copper tile are wrapped on the two end cylindrical surfaces respectively.

8. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness according to claim 7, characterized in that: The upper supporting spring piece is a spring piece with the same width as the flexural leaf spring and curved into an arch shape in the length direction, and the cylindrical concave surface at the middle part forms a pair of friction pair type connection with the upper supporting copper tile of the flexural leaf spring; the lower supporting spring piece is a spring piece with the same width as the flexural leaf spring and curved into an arch shape in the length direction, and the cylindrical concave surface at the middle part forms a pair of friction pair type connection with the lower supporting copper tile of the flexural leaf spring.

9. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness of claim 7, wherein: The upper supporting block is a load bearing part allowing only up and down movement, and the lower left direction is an arch concave surface, which forms a corresponding matching relationship with the arch convex surface of the upper supporting spring piece, and the gap reserved between the arch concave surface of the upper supporting block and the arch convex surface of the upper supporting spring piece is filled with the upper supporting rubber piece and bonded and vulcanized together as a whole; the lower supporting block is a load bearing part placed on the base platform and limiting horizontal movement, and the upper right direction is an arch concave surface, which forms a corresponding matching relationship with the arch convex surface of the lower supporting spring piece, and the gap reserved between the arch concave surface of the lower supporting block and the arch convex surface of the lower supporting spring piece is filled with the lower supporting rubber piece and bonded and vulcanized together as a whole.

10. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness of claim 7, wherein: The flexural leaf spring is a flat spring piece, which is a rectangular sheet with the width being 1 / 3-1 / 2 of the length, and slightly curved downward at the middle part in the length direction, and provided with a cylindrical surface with the width direction as the axis at the two ends in the length direction, and the radius of the cylindrical surface is 1.3-1.8 times of the thickness of the spring piece, and the end cylindrical surface is circularly arc transitioned with the upper and lower surfaces in the thickness direction of the spring piece.

11. The quasi-zero stiffness vibration isolation device based on a rotatable leaf spring generating negative stiffness of claim 7, wherein: The length (L) of the flexural leaf spring is 14-25 mm; the thickness is 0.6-1 mm; and the initial angle (A) of the flexural leaf spring is 15-25 degrees.

Images