A negative stiffness elastomeric rotatable node for a quasi-zero stiffness vibration isolation device

Abstract

A kind of negative stiffness elastic rotatable node for quasi-zero stiffness vibration isolation device, quasi-zero stiffness vibration isolation device includes positive stiffness component, negative stiffness mechanism, by the combination of positive stiffness component and negative stiffness mechanism to form quasi-zero stiffness vibration isolation device;There is rotatable node in negative stiffness mechanism;Rotatable node is elastic rotatable node, and rotatable node includes elastic layer, and elastic layer is bonded on the negative stiffness node support block of quasi-zero stiffness vibration isolation device;Node support sheet is bonded on the elastic layer and covered, and node support sheet wraps negative stiffness leaf spring, and together with the end of negative stiffness leaf spring to form elastic rotatable node.The present application uses elastic rotatable node, so that leaf spring can be compressed elastic layer during moving up and down and rotating, make up the adverse effect caused by the change of the length of negative stiffness leaf spring in horizontal direction, so as to obtain good quasi-zero stiffness negative stiffness adjustment result, realize quasi-zero stiffness vibration isolation, with the characteristics of simple structure and high reliability.

Description

Technical Field

[0001] This invention relates to a component of a quasi-zero stiffness vibration isolation device, and more particularly to a negative stiffness elastic rotatable node for a quasi-zero stiffness vibration isolation device; the negative stiffness elastic rotatable node for a quasi-zero stiffness vibration isolation device can truly realize the controllability and adjustability of negative stiffness, achieve the quasi-zero stiffness vibration isolation effect, and 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] Quasi-zero stiffness vibration isolation devices are a representative type of vibration isolation device characterized by high static and low dynamic stiffness. Their main approach involves connecting positive and negative stiffness elastic elements in parallel at a static level position to achieve a combined vibration isolator with zero stiffness. By rationally optimizing the geometric and stiffness parameters of the negative stiffness mechanism, the vibration isolation system can achieve both high load-bearing capacity and superior low-frequency vibration isolation performance. Compared to traditional passive vibration isolation systems, quasi-zero stiffness has the following three advantages:

[0003] 1) Due to its nonlinear stiffness term, it has good static load-bearing capacity and small structural deformation;

[0004] 2) The system's natural frequency decreases, and the vibration isolation bandwidth widens;

[0005] 3) The stiffness characteristics of the system can be flexibly adjusted according to different working conditions.

[0006] The load-bearing capacity of the quasi-zero stiffness vibration isolation device is determined by the positive stiffness spring, while the negative stiffness element is used to reduce the dynamic stiffness of the system. The parallel connection of positive and negative stiffness has the characteristics of high static and low dynamic stiffness, thereby significantly reducing the system stiffness, widening the system's vibration isolation frequency band, and improving the system's vibration isolation performance, especially improving the low-frequency vibration isolation performance, while ensuring the system's load-bearing capacity.

[0007] Currently, research on positive stiffness is quite mature, but research on negative stiffness is still in its early stages. Many proposed negative stiffness generating mechanisms utilize rotating nodes, which cause a positional change in the actuator, thus generating negative stiffness. In recent years, quasi-zero stiffness vibration isolation technology has become a research hotspot for scholars both domestically and internationally. Therefore, the design and application of quasi-zero stiffness vibration isolators has become a goal pursued in the field of vibration reduction / isolation technology.

[0008] However, current research on quasi-zero stiffness is mainly confined to scientific research conducted by some universities, lacking truly practical "quasi-zero stiffness" vibration isolation devices that can be applied in engineering. Through analysis, current research on "quasi-zero stiffness" vibration isolation devices mainly focuses on achieving quasi-zero stiffness by connecting negative stiffness mechanisms in parallel to positive stiffness systems. Although there are many literature reports on so-called "quasi-zero stiffness vibration isolation," most of the so-called "quasi-zero stiffness" vibration isolation devices currently being introduced are only theoretical and lack practical value for engineering applications.

[0009] Especially for the use of rotating hinges to deform springs and create negative stiffness, most solutions only propose simple ball joints or hinges to meet the rotation requirements. Through analysis of practical applications, it has been found that this rigid rotation method is difficult to meet the requirements of negative stiffness, and it is easy to cause excessive stress on the actuator during operation, or even cause it to jam during operation. Therefore, it is necessary to improve this method.

[0010] A search revealed no literature reports identical to the technical solution of this invention, only some similar reports, among which the following are most relevant to this application:

[0011] 1. The invention patent entitled "A Quasi-Zero Stiffness Vibration Damper for Rail Vehicle Seats" (CN202111448030.5) discloses a quasi-zero stiffness vibration damper for rail vehicle seats. The quasi-zero stiffness vibration damper includes a cylindrical hollow disc spring outer mounting seat with an open upper end, a cylindrical hollow disc spring inner mounting seat with an open lower end, a disc spring, and a spring damping vibration damping unit. The disc spring inner mounting seat is fastened inside the disc spring outer mounting seat, and the two ends of the spring damping vibration damping unit are respectively hinged to the bottom of the disc spring inner mounting seat and the disc spring outer mounting seat. The disc spring is disposed in the annular space between the disc spring inner mounting seat and the disc spring outer mounting seat.

[0012] 2. A utility model patent entitled "A Quasi-Zero Stiffness Vibration Isolator Suitable for Variable Load Mass" (CN202120434799.0) discloses a quasi-zero stiffness vibration isolator suitable for variable load mass, including a bottom frame and a top cover. The top cover is horizontally disposed on the top of the bottom frame. A positive stiffness spring is fixedly connected to the center of the bottom inner part of the bottom frame. A negative stiffness top rod connecting sleeve corresponding to the positive stiffness spring is fixedly connected to the bottom of the top cover. Multiple sets of negative stiffness top rods are arranged around the inner wall of the bottom frame. One end of the negative stiffness top rod is rotatably connected to the inner wall of the bottom frame through a thin leaf spring. The end of the negative stiffness top rod away from the thin leaf spring is provided with a first connecting head.

[0013] 3. An invention patent entitled "An Encapsulated Constant-Stiffness Zero-Stiffness Vibration Isolator" (CN202110970017.X) describes an encapsulated constant-stiffness zero-stiffness vibration isolator, comprising a fixed outer shell, an upper elastic frame, a lower elastic frame, compression rods, and an intermediate block. The fixed outer shell is a box-shaped structure with a guide hole extending vertically through its top. The lower elastic frame is an elastic structure with vertical extension and contraction. The upper elastic frame is an elastic structure with vertical extension and contraction. There are an even number of compression rods, arranged in pairs around the intermediate block. In the initial position, the end of the compression rod that abuts against the intermediate block is higher than the hinge. Under the pressure of the workpiece to be isolated, it undergoes buckling deformation and rotates around the hinge to a horizontal position, reaching the optimal working position.

[0014] Careful analysis reveals that while these patents all involve quasi-zero stiffness and negative stiffness elements, and all employ rotating components within the negative stiffness elements, the rotating node components disclosed in these patents all utilize fixed rigid rotating components to achieve component rotation. This indicates a problem or drawback in the existing technology:

[0015] 1. When using rigid rotating joints, uneven force distribution can easily occur in the actuators of the components forming negative stiffness during the process of creating negative stiffness, such as spring jamming.

[0016] 2. Using rigid rotating joints will result in poor vibration resistance of the rotating joints themselves, which is not conducive to accurately determining the magnitude of negative stiffness;

[0017] 3. Using rigid rotating joints will significantly increase the stress on the negative stiffness actuator during the negative stiffness deformation process, which can easily cause damage to the negative stiffness actuator and shorten its service life.

[0018] 4. The rotating joints of existing negative stiffness components are complex to install and difficult to maintain;

[0019] 5. The existing proposed rotation nodes for negative stiffness components are not valuable for engineering applications and are difficult to implement.

[0020] Therefore, in order to solve the problems caused by the use of rigid rotating node components in the negative stiffness forming components in existing quasi-zero stiffness systems, it is necessary to improve this approach. Summary of the Invention

[0021] The technical problem to be solved by the present invention is to provide a negative stiffness elastic rotatable node for a quasi-zero stiffness vibration isolation device that has practical application value and can be mass-produced and sold, thereby solving the technical shortcomings of existing vibration isolators that are complex to install and difficult to maintain.

[0022] This invention is mainly achieved through the following technical solution: a negative stiffness elastic rotatable node for a quasi-zero stiffness vibration isolation device. The quasi-zero stiffness vibration isolation device includes a positive stiffness component and a negative stiffness component, which are combined to form the quasi-zero stiffness vibration isolation device. The negative stiffness mechanism includes a leaf spring and a rotatable node. The leaf spring is connected to the negative stiffness support component through the rotatable node, and the negative stiffness is formed by the up-and-down movement and rotation of the leaf spring. At least one of the rotatable nodes is an elastic rotatable node, which includes an elastic layer bonded to the negative stiffness node support block of the quasi-zero stiffness vibration isolation device. A node support plate is bonded and covered on the elastic layer, which wraps around the negative stiffness leaf spring and together with the end of the negative stiffness leaf spring, forms an elastic rotatable node. In this way, the elastic deformation of the elastic rotatable node can effectively adjust the stress condition of the negative stiffness mechanism to form a suitable negative stiffness.

[0023] Furthermore, the elastic layer can be an elastic rubber layer or an elastic polymer material layer, which is vulcanized or bonded and embedded in the negative stiffness node support block to form the elastic layer of the rotating node.

[0024] Furthermore, the elastic rubber layer or elastic polymer material is vulcanized or bonded and embedded in the negative stiffness node support block by carving a groove on the side of the negative stiffness node support block, and then vulcanizing or bonding an elastic rubber or elastic polymer material in the groove, so that the elastic rubber or elastic polymer material is embedded in the negative stiffness node support block to form the elastic layer of the rotatable node.

[0025] Furthermore, the groove includes an arc-shaped groove or a rectangular groove; the elastic rubber layer or elastic polymer material layer is integrally vulcanized or bonded and embedded in the arc-shaped groove or rectangular groove.

[0026] Furthermore, the upper and lower ends of the groove are not on the same plane, and are determined according to the force direction of the negative stiffness node support block. The surface above the force direction of the negative stiffness leaf spring on the negative stiffness node support block is the protruding surface, and the surface below the direction of the reaction force of the negative stiffness node support block on the negative stiffness leaf spring is the concave surface, ensuring that the rotatable node will not slip when it moves up and down and rotates.

[0027] Furthermore, the node support plate is a long, thin strip with an arc-shaped concave surface. The node support plate has an arc-shaped ball joint recess in the middle, which serves as a support surface. The curvature of the arc-shaped ball joint recess matches the rotating ball heads at both ends of the negative stiffness leaf spring, so that when the negative stiffness leaf spring is installed in the negative stiffness mechanism, the rotating ball heads at both ends of the negative stiffness leaf spring are precisely engaged in the arc-shaped ball joint recess of the node support plate, forming a rotatable node.

[0028] Furthermore, the node support piece is vulcanized on the outer surface of the elastic rubber layer, and the arc-shaped ball joint recess of the node support piece extends into the elastic rubber layer, forming a compression on the arc-shaped surface of the elastic rubber layer.

[0029] Furthermore, the width of the node support plate is the same as the width of the negative stiffness leaf spring, ensuring that the negative stiffness leaf spring as a whole can rotate freely up and down within the node support plate.

[0030] Furthermore, the node support plate and the negative stiffness leaf spring are provided with protective copper tiles; the protective copper tiles are wrapped around the rotating ball head at the end of the negative stiffness leaf spring, and then assembled into the arc-shaped ball joint recess of the node support plate to form a rotational protective layer.

[0031] Furthermore, the negative stiffness leaf spring is a rectangular leaf spring with a width approximately half its length and a slight downward curve along the middle of its length. Both ends of the leaf spring have cylindrical surfaces with the width direction as their axis. The radius of the cylindrical surfaces is approximately 1.5 times the thickness of the leaf spring. The cylindrical surfaces at the ends are connected to the upper and lower surfaces of the negative stiffness leaf spring in the thickness direction by a circular arc transition, forming rotating ball heads at the ends of the negative stiffness leaf spring.

[0032] This type of negative stiffness elastic rotatable node is mainly used in negative stiffness mechanisms of leaf springs. By installing this type of negative stiffness elastic rotatable node at one or both ends of the negative stiffness leaf spring, the deformation and force of the negative stiffness leaf spring can be adjusted by compressing the negative stiffness elastic rotatable node when the negative stiffness is formed, thereby improving the environment for the formation of negative stiffness.

[0033] The working principle of the elastic rotatable node in the negative stiffness mechanism is as follows: There are two negative stiffness node support blocks, installed at both ends of the negative stiffness leaf spring, one on top and one on the bottom, namely the upper support block and the lower support block. Both the upper and lower support blocks are restricted from horizontal movement and are bonded or vulcanized with the elastic rotatable node to form a whole. 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 elastic element → upper support spring plate → upper support copper tile → buckling leaf spring → lower support copper tile → lower support spring plate → lower support elastic element → lower support block. During this process, the elastic element undergoes elastic compression deformation, the metal spring plate undergoes elastic bending deformation, and 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 the vertical component of the negative stiffness unit, i.e., the support reaction force, decreasing in magnitude. 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.

[0034] The negative stiffness unit is installed in the negative stiffness mechanism; wherein, the lower support block of the negative stiffness unit is designed as a ring to form the inner ring of the negative stiffness device; the upper support block of the negative stiffness unit is designed as a ring to form the outer ring of the negative stiffness device; 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 unit assembly.

[0035] The beneficial effects of this invention are as follows: By replacing the rotating node formed by negative stiffness with an elastic rotatable node, the leaf spring can compensate for the adverse effects of changes in the horizontal length of the negative stiffness leaf spring during its vertical movement and rotation by compressing the elastic layer. This achieves excellent quasi-zero stiffness adjustment, realizing low-frequency quasi-zero stiffness vibration isolation performance. It can achieve low or near-zero dynamic stiffness in a static equilibrium state, solving the problem of traditional linear vibration isolation systems 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 plate vibration damping tracks. It features a simple structure, high reliability, and long service life. Attached Figure Description

[0036] Figure 1 Schematic diagram of an elastic rotating node structure formed by negative stiffness;

[0037] Figure 2 This is a schematic diagram of the structure of the present invention used in a quasi-zero stiffness vibration isolation device;

[0038] Figure 3 This is a schematic diagram of the negative stiffness device of the present invention;

[0039] Figure 4 This is a schematic diagram of the negative stiffness mechanism of the negative stiffness device of the present invention;

[0040] Figure 5 This is a schematic diagram of the negative stiffness unit combination mechanism of the negative stiffness mechanism of the present invention;

[0041] Figure 6 This is a schematic diagram of the negative stiffness unit structure of the present invention;

[0042] Figure 7 This is a schematic diagram of the leaf spring structure of the present invention;

[0043] Figure 8 This is a schematic diagram of the negative stiffness adjustment curve.

[0044] Figure 9 This is a schematic diagram of another type of rectangular groove negative stiffness unit structure. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0046] From the appendix Figure 1 It can be seen that the elastic rotating node formed by negative stiffness mainly includes a support base (1), an elastic layer (2), a rotating hinge support plate (3), and a rotating node rotating part (4). A groove (5) is opened on the support base (1), the elastic layer (2) is embedded in the groove (5) of the support base (1), the rotating hinge support plate (3) is bonded to the outer surface of the elastic layer (2), and the rotating node rotating part (4) is stuck in the cylindrical hinge groove (7) of the rotating hinge support plate (3). The rotating node rotating part (4) can rotate up and down by an angle A in the cylindrical hinge groove (7) and compress the elastic layer (2) during the rotation process to form a negative stiffness elastic rotatable node. In order to ensure the rotation effect of the rotating node rotating part (4) on the rotating hinge support plate (3), reduce the friction between them, and extend the service life of the rotatable node, a friction pad (6) is provided between the rotating hinge support plate (3) and the rotating node rotating part (4). The friction pad (6) reduces the frictional resistance between the rotating hinge support plate (3) and the rotating node rotating part (4).

[0047] There are many ways to apply negative stiffness elastic rotatable nodes. Several embodiments will be listed below to further describe the present invention. Example 1

[0048] This embodiment describes a vibration isolation device for quasi-zero stiffness, as shown in the attached diagram. Figure 2 As shown, the quasi-zero stiffness vibration isolation device includes a positive stiffness component (8), a height adjustment plate (9), and a negative stiffness mechanism (10); the positive stiffness component (8), the height adjustment plate (9), and the negative stiffness mechanism (10) are all installed inside the outer sleeve (12), and the bottom surface of the positive stiffness component (8) extends from the bottom of the outer sleeve (12), exceeding the bottom surface of the outer sleeve (12), forming a horizontal height difference; the negative stiffness mechanism (10) is installed inside the outer sleeve (12) and is located on the positive stiffness component (8). The upper end face of the negative stiffness mechanism (10) extends out of the upper end face of the outer sleeve (12), and the negative stiffness mechanism (10) moves together with the outer sleeve (12) 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 mechanism (10) is a composite sheet spring negative stiffness mechanism, which generates negative stiffness.

[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 quasi-zero stiffness vibration isolation device is composed of a positive stiffness component (8), a height adjustment pad (9), and a negative stiffness mechanism (10). The positive stiffness component (8) and the negative stiffness mechanism (10) are coaxially connected in parallel and supported on the bearing support ring (15) in the outer sleeve (12) 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 mechanism (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 achieving good low-frequency vibration isolation performance and improving the system's vibration isolation efficiency.

[0051] like Figure 3 As shown: The negative stiffness mechanism (10) includes an outer bearing component (16), an inner bearing component (17), a negative stiffness forming component (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 forming component (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 forming component (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).

[0052] The negative stiffness mechanism (10) has a rotatable node (33); the rotatable node (33) is an elastic rotatable node, which includes an elastic layer, which is bonded to the negative stiffness node support block of the quasi-zero stiffness vibration isolation device; a node support plate is bonded and covered on the elastic layer, which wraps around the negative stiffness leaf spring and together with the end of the negative stiffness leaf spring, forms an elastic rotatable node.

[0053] like Figure 4 As shown: The negative stiffness forming component (18) is formed by stacking multiple negative stiffness units (20) along the plumb line.

[0054] like Figure 5 As shown: The negative stiffness unit combination (20) is formed by multiple negative stiffness units (23) arranged in a ring on the same plane; each of the negative stiffness units (23) has rotatable nodes (22) and (21) at both ends, and the rotatable nodes (22) and (21) are both elastic rotatable nodes.

[0055] like Figure 6 As shown: Specifically, the negative stiffness unit (23) 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 negative stiffness 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.

[0056] The upper support block (24) 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 (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 with the upper support rubber component (25) and bonded and vulcanized together. 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 with an arc-shaped concave surface, which corresponds to 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 with the lower support rubber component (31) and bonded and vulcanized together.

[0057] The upper support rubber component (25) and the lower support rubber component (31) are elastic rubber layers. The elastic rubber layers are vulcanized and embedded in the upper support block (24) or the lower support block (32) to form an elastic layer for the rotating node. The upper support rubber component (25) and the lower support rubber component (31) are vulcanized and embedded in the upper support block (24) or the lower support block (32) by carving out an arc-shaped groove on the side of the upper support block (24) or the lower support block (32), and then vulcanizing the upper support rubber component (25) and the lower support rubber component (31) in the arc-shaped groove, so that the upper support rubber component (25) and the lower support rubber component (31) are embedded in the upper support block (24) or the lower support block (32) to form an elastic layer for the rotating node (33).

[0058] Moreover, the upper and lower ends of the arc-shaped groove on the upper support block (24) or the lower support block (32) are not on the same plane, and are determined according to the force direction of the negative stiffness node support block. The surface above the force direction of the negative stiffness leaf spring on the negative stiffness node support block is the protruding surface, and the surface below the direction of the reaction force of the negative stiffness node support block on the negative stiffness leaf spring is the concave surface, so as to ensure that the rotatable node (33) will not slip when it moves up and down and rotates.

[0059] The upper support spring plate (27) and the lower support spring plate (29) are long strips with an arc-shaped concave surface. The node support plate has an arc-shaped ball joint recess in the middle, which serves as the support surface. The arc of the arc-shaped ball joint recess matches the rotating ball heads at both ends of the negative stiffness plate spring, so that when the negative stiffness plate spring is installed in the negative stiffness mechanism, the rotating ball heads at both ends of the negative stiffness plate spring are precisely locked in the arc-shaped ball joint recess of the node support plate, forming a rotatable node (33).

[0060] The upper support spring sheet (27) and the lower support spring sheet (29) are vulcanized on the outer surface of the elastic rubber layer. The arc-shaped cylindrical surface recesses of the upper support spring sheet (27) and the lower support spring sheet (29) extend into the elastic rubber layer, forming a compression on the arc-shaped surface of the elastic rubber layer.

[0061] The widths of the upper support spring plate (27) and the lower support spring plate (29) are the same as the width of the negative stiffness leaf spring (28), ensuring that the negative stiffness leaf spring (28) can rotate freely up and down within the upper support spring plate (27) and the lower support spring plate (29). The upper support spring plate (27) is a spring plate with a width consistent with the width of the bent leaf spring (28), but bent into a bow-like shape along its length. Its cylindrical concave surface in the middle forms a friction pair with the upper support copper plate (26) of the bent leaf spring (28). 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 a bow-like shape along its length. Its cylindrical concave surface in the middle forms a friction pair with the lower support copper plate (30) of the bent leaf spring (28).

[0062] The upper support spring plate (27) and the lower support spring plate (29) are provided with protective copper tiles at both ends of the negative stiffness leaf spring (28); namely, the upper support copper tile (26) and the lower support copper tile (30); the protective copper tile is wrapped around the rotating ball head at the end of the negative stiffness leaf spring, and then assembled into the arc-shaped ball joint recess of the node support plate to form a rotation protection layer.

[0063] As attached Figure 7 As shown, the negative stiffness leaf spring (28) is a rectangular spring sheet with a width approximately half of its length (L) and a slight downward bend along the middle of the length direction. At both ends of the length direction, cylindrical surfaces are provided with the width direction as the axis. The radius of the cylindrical surfaces is approximately 1.5 times the thickness of the spring sheet. The cylindrical surfaces at the ends are connected to the upper and lower surfaces of the negative stiffness leaf spring in the thickness direction by a circular arc transition, forming a rotating ball head at the end of the negative stiffness leaf spring.

[0064] The negative stiffness leaf spring (28) has an inclined angle (A) between its length direction and the horizontal plane. The cylindrical surfaces at both ends of the spring form the upper and lower joint support surfaces, and copper tiles, namely the upper support copper tile (26) and the lower support copper tile (30), are wrapped on the cylindrical surfaces at both ends.

[0065] 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 assembled into a whole with the other elastic components through rubber bonding, vulcanization and assembly. 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, as shown in the attached figure. Figure 6As shown, the force transmission path under the action of the loading force 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 undergoes elastic compression deformation, the metal spring plate undergoes elastic buckling deformation, and at the same time, the angle (A) between the length direction of the negative stiffness 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 negative stiffness leaf spring (28) and the horizontal plane is zero, the component force of the negative stiffness unit in the vertical direction, that is, 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 stiffness curve similar to a parabola, as shown in the attached figure. Figure 8 As shown.

[0066] The negative stiffness unit (20) and the negative stiffness unit, wherein the lower support block (32) of the negative stiffness unit is designed as a ring to form the inner ring (21) of the negative stiffness unit (20); the upper support block (24) of the negative stiffness unit is designed as a ring to form the outer ring (22) of the negative stiffness unit (20); the negative stiffness leaf spring (28) in the negative stiffness unit is evenly arranged in a similar slotted disc spring along the circumferential direction and 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 to form the negative stiffness unit (20). Example 2

[0067] 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 for a floating slab track bed in a tunnel space. The quasi-zero stiffness vibration isolation device includes a positive stiffness component, a negative stiffness mechanism, and an adjustment pad. The positive stiffness component, negative stiffness component, and adjustment pad 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 installed inside the outer sleeve and is located above the positive stiffness component. The upper end surface of the negative stiffness component extends beyond the upper end surface of the outer sleeve and moves with the floating track bed as it moves up and down, generating negative stiffness during this movement. The resultant force formed by this 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 composite sheet spring negative stiffness mechanism, which generates negative stiffness.

[0068] However, the elastic layer (201) of the elastic rotation node of the negative stiffness unit in the aforementioned negative stiffness component is made of a polymer elastomer, preferably a polyurethane elastomer modified material. The polyurethane elastomer modified material is integrally injection molded into the rectangular groove (204) of the upper support (202) or lower support (203) to form the elastomer, as shown in the attached figure. Figure 9 As shown in the figure. This design features simple upper or lower support base manufacturing, making it convenient for processing and production.

[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.

[0070] 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.

[0071] The beneficial effects of this invention are:

[0072] This invention replaces the rotating node formed by negative stiffness with an elastic rotatable node. This allows the leaf spring to compensate for the adverse effects of changes in the horizontal length of the negative stiffness leaf spring during its vertical movement and rotation by compressing the elastic layer. This achieves excellent quasi-zero stiffness adjustment, realizing low-frequency quasi-zero stiffness vibration isolation performance. It achieves low or near-zero dynamic stiffness in static equilibrium, solving the problem of traditional linear vibration isolation systems 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. It features a simple structure, high reliability, and long service life. Its main advantages are as follows:

[0073] 1. A rotatable joint is used to connect the rotatable leaf spring, allowing both ends of the rotatable 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 force that was previously caused by piston-type rod extension and retraction. By adjusting the air posture of the rotatable leaf spring through the rotation of the rotatable joint, negative stiffness is created, eliminating the jamming problem during the process. Therefore, it is possible to truly realize the engineering application of quasi-zero stiffness vibration isolation through negative stiffness intervention.

[0074] 2. The rotatable node adopts an elastic compressible structure. When the rotatable leaf spring rotates from the inclined plane to the horizontal plane, 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.

[0075] 3. 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.

[0076] 4. 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.

[0077] 5. This negative stiffness device 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 negative stiffness rotatable node for a quasi-zero stiffness vibration isolation device, the quasi-zero stiffness vibration isolation device comprising a positive stiffness component, a negative stiffness component, the quasi-zero stiffness vibration isolation device being formed by the combination of the positive stiffness component and the negative stiffness component; the negative stiffness component having the rotatable node therein; characterised in that: The rotatable node has at least one elastic rotatable node, which includes an elastic layer bonded to the negative stiffness node support block of the quasi-zero stiffness vibration isolation device; a node support sheet is bonded to the elastic layer and covers the negative stiffness sheet spring, and together with the end of the negative stiffness sheet spring forms a negative stiffness elastic rotatable node; the elastic rubber layer or the elastic polymer material is integrally vulcanized or bonded in the negative stiffness node support block, a groove is dug on the side of the negative stiffness node support block, and an elastic rubber layer or an elastic polymer material is integrally vulcanized or bonded in the groove, so that the elastic rubber layer or the elastic polymer material embedded in the negative stiffness node support block forms the elastic layer of the rotatable node; the upper and lower ports of the groove are not on the same plane, and are determined according to the stress point direction of the negative stiffness node support block, the upper part of the stress direction of the negative stiffness sheet spring to the stress point of the negative stiffness node support block is the protruding surface, and the lower part of the reaction force direction of the negative stiffness node support block to the negative stiffness sheet spring is the low concave surface, so as to ensure that the rotatable node will not slip when moving up and down and rotating.

2. A negative stiffness elastomeric rotatable node for a quasi-zero stiffness isolation device according to claim 1, wherein: The groove includes a circular arc groove or a rectangular groove; the elastic rubber layer or the elastic polymer material layer is integrally vulcanized or bonded in the circular arc groove or the rectangular groove.

3. A negative stiffness elastomeric rotatable node for a quasi-zero stiffness isolation device according to claim 1, wherein: The node support sheet is a concave long strip sheet with an arc shape, the middle of the node support sheet has an arc-shaped spherical hinge pit, and the arc-shaped spherical hinge pit is a support surface; the curvature of the arc-shaped spherical hinge pit is matched with the rotating spherical heads at both ends of the negative stiffness sheet spring, so that when the negative stiffness sheet spring is installed in the negative stiffness mechanism, the rotating spherical heads at both ends of the negative stiffness sheet spring are clamped in the arc-shaped spherical hinge pit of the node support sheet, forming a rotatable node.

4. A negative stiffness elastomeric rotatable node for a quasi-zero stiffness isolation device according to claim 3, wherein: The node support sheet is vulcanized on the outer surface of the elastic rubber layer, and the arc-shaped spherical hinge pit of the node support sheet extends into the elastic rubber layer, forming extrusion on the arc-shaped surface of the elastic rubber layer.

5. A negative stiffness elastomeric rotatable node for a quasi-zero stiffness isolation device according to claim 3, wherein: The width of the node support sheet is the same as the width of the negative stiffness sheet spring, and the negative stiffness sheet spring can freely rotate up and down in the node support sheet.

6. A negative stiffness elastomeric rotatable node for a quasi-zero stiffness isolation device according to claim 3, wherein: The node support sheet and the negative stiffness sheet spring are provided with a protective copper tile; the protective copper tile is wrapped around the rotating spherical head at the end of the negative stiffness sheet spring, and is assembled into the arc-shaped spherical hinge pit of the node support sheet, forming a rotating protection layer.

7. A negative stiffness elastomeric rotatable node for a quasi-zero stiffness isolation device according to claim 1, wherein: The negative stiffness sheet spring is a rectangular spring sheet, the width of which is about half of the length, and the middle of the length direction is slightly curved downward, the two ends of the length direction are provided with a cylindrical surface with the width direction as the axis, the radius of the cylindrical surface is about 1.5 times the thickness of the spring sheet, and the end cylindrical surface is circularly transitioned with the upper and lower surfaces in the thickness direction of the spring sheet, forming a cylindrical rotating spherical head at the end of the negative stiffness sheet spring.

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