A negative stiffness device for quasi-zero stiffness vibration isolation

Abstract

A negative stiffness device for quasi-zero stiffness vibration isolation, the negative stiffness device comprising a ring-shaped inner ring, a ring-shaped outer ring and a negative stiffness mechanism; the mechanism is formed by vertically superimposed combination of a plurality of negative stiffness units, and the unit combination is formed by continuous arrangement of a plurality of negative stiffness units in the circumferential direction on the same plane to form a ring-shaped ring, forming a multi-layer ring-shaped negative stiffness mechanism; each negative stiffness unit has a rotatable leaf spring, both ends of the rotatable leaf spring are connected to rotatable nodes, and at least one rotatable node is a compressible elastic rotatable node; the rotatable leaf spring moves up and down under the action of the ring-shaped inner ring and the ring-shaped outer ring, and rotates around the rotatable node, gradually changes to horizontal by the slope, and forms negative stiffness. The present application obtains negative stiffness by the rotatable leaf spring moving up and down and rotating around the rotatable node between the ring-shaped inner ring and the ring-shaped outer ring, and meets the quasi-zero stiffness vibration isolation requirement; has the characteristics of simple structure and high reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to a negative stiffness device, in particular to a negative stiffness device for quasi-zero stiffness vibration isolation; the negative stiffness device for quasi-zero stiffness vibration isolation can truly realize controllable and adjustable negative stiffness, achieve quasi-zero stiffness vibration isolation effect, and is convenient to manufacture and has high reliability; and belongs to the technical field of vibration reduction and isolation. BACKGROUND

[0002] Quasi-zero stiffness vibration isolation technology has become the ideal vibration isolation technology and has become a research hotspot for domestic and foreign scholars by obtaining high static stiffness and low dynamic stiffness to ensure good low-frequency vibration isolation performance on the basis of bearing capacity. Quasi-zero stiffness vibration isolation is a kind of vibration isolation with dynamic stiffness close to zero. The vibration isolator with high static and low dynamic stiffness has a stiffness that changes with the compression amount. At zero load, the vibration isolator has large static stiffness (bearing stiffness) to ensure high bearing capacity and small static displacement. When the load compresses the vibration isolator to the static equilibrium position, the dynamic stiffness of the vibration isolator is greatly reduced. Therefore, the vibration isolator has high bearing capacity and low natural frequency, effectively solving the bottleneck problem of passive vibration isolation. Quasi-zero stiffness vibration isolator is a very representative vibration isolator with high static and low dynamic stiffness characteristics. At present, there are mainly three design forms as follows:

[0003] One is to connect a negative stiffness mechanism in parallel to a positive stiffness system to achieve quasi-zero stiffness; the second is to use the nonlinear relationship between the structure force and deformation of a specific shape to achieve quasi-zero stiffness; and the third is to use a new vibration isolation mechanism. However, the main method of truly entering engineering application at present is still to connect a negative stiffness mechanism in parallel to a positive stiffness system to achieve quasi-zero stiffness. There are many literatures about so-called "quasi-zero stiffness vibration isolation" at present, but there is no truly engineering application technical scheme. The most relevant to the present application are as follows:

[0004] The utility model discloses a low-frequency vibration isolator with super-wide quasi-zero stiffness interval (CN202223354862.3), which comprises a bottom frame and a top cover. The top cover is horizontally arranged on the top of the bottom frame. The inner bottom center of the bottom frame is provided with a first supporting ring. The bottom of the top cover is fixedly connected with a second supporting ring corresponding to the first supporting ring. The bottom of the top cover is fixedly connected with a negative stiffness mechanism mounting sleeve corresponding to the second supporting ring. The edges of the first supporting ring and the second supporting ring are connected by a plurality of arc steel wire ropes. The bottom center of the second supporting ring is fixedly connected with a guide rod. The top of the first supporting ring is fixedly connected with a through hole corresponding to the guide rod.

[0005] The invention patent with the patent name "Quasi-zero stiffness vertical vibration isolator and design method thereof, and three-dimensional vibration isolation device" (CN202211120961.7) includes a bottom plate, a cover plate, a positive stiffness elastic element, and a negative stiffness elastic element. The positive stiffness elastic element and the negative stiffness elastic element are pre-compressed between the bottom plate and the cover plate. The positive stiffness elastic element and the negative stiffness elastic element are both disc spring groups composed of disc springs. The positive stiffness elastic element includes a middle disc spring group arranged at the center of the bottom plate and a small disc spring group located at the outer periphery of the middle disc spring group. The negative stiffness elastic element is a large disc spring group located at the outer periphery of the positive stiffness elastic element. The radii of the disc springs in the small disc spring group, the middle disc spring group, and the large disc spring group increase in order.

[0006] 3. The invention patent with the patent name "Vibration reduction design and optimization method and system of double-layer high-static and low-dynamic stiffness vibration isolation system" (CN202210866695.6) includes the following steps: S1: building the system, connecting a pair of Euler buckling beam negative stiffness adjusters in parallel on the upper and lower layers of the double-layer linear vibration isolation system; S2: principle analysis of high-static and low-dynamic stiffness, giving the relationship between the external force and displacement of the entire system; S3: giving the constraint relationship between the linear terms κ11 and κ12 of the total stiffness of the upper and lower layers of the structure, obtaining the effective value range; S4: establishing the dynamics equation of the system and solving it; S5: changing the total linear stiffness κ11 and κ12 of the upper and lower layers according to the effective value range obtained in step S2, obtaining the optimal double-layer high-static and low-dynamic stiffness system.

[0007] Problems or shortcomings of the prior art:

[0008] Although the above-mentioned patents involve negative stiffness units and propose some improved technical solutions, careful analysis shows that these patents cannot be truly used in actual engineering. Among them,

[0009] Patent 1 only provides a quasi-zero stiffness negative stiffness device with a super-wide distance, but uses the conventional negative stiffness top rod method. This negative stiffness formation method is found to be complex in actual application, and the effect is not very good. It is difficult to maintain uniform stress in all directions, and the phenomenon of jamming is likely to occur. Moreover, the negative stiffness in this method is mainly realized by pulling the linear spiral spring arranged in the sleeve by the negative stiffness rod. The structure is complex, and the negative stiffness rod is prone to jamming under the action of the vertical force. The stability of the entire negative stiffness system is very unstable, and it is difficult to achieve the effect of negative stiffness vibration reduction in actual quasi-zero stiffness vibration isolation.

[0010] Patent 2 proposes a way to achieve negative stiffness by using large, medium and small disc springs. This method is theoretically feasible, but it is difficult to control the deformation of the disc spring in practical application. In particular, when the disc spring is close to horizontal, it is easy to turn over and fail, so it is not advisable to use disc springs to achieve negative stiffness.

[0011] Patent 3 proposes a negative stiffness adjustment method using an Euler buckling beam. This patent discloses a method for calculating negative stiffness in the case of an Euler buckling beam, and also relates to a rotating structure with hinged constraints at both ends. However, in practice, it is found that this method ignores the horizontal displacement of the linear spring during its upward and downward displacement, which is not advisable because it is this horizontal displacement that changes the size of the vertical component force. Therefore, the negative stiffness calculated in this way is difficult to achieve the effect of quasi-zero stiffness vibration isolation.

[0012] From the information disclosed in the above patents, it can be seen that although there are many studies on the use of negative stiffness devices to add positive stiffness systems to achieve quasi-zero stiffness vibration isolation, most of them are still theoretical studies and do not have much value in engineering applications. Some of them are complex in structure and not suitable for installation and use in special spaces, so it is necessary to improve them. SUMMARY

[0013] The technical problem to be solved by the present application is the lack of engineering application of existing negative stiffness devices added to positive stiffness systems, which are complex in structure and prone to jamming. The present application provides a negative stiffness unit device applied in a quasi-zero stiffness system to resist positive stiffness. This negative stiffness unit not only achieves negative stiffness, but also has a simple structure, is easy to manufacture, and has high engineering application value.

[0014] The present application mainly realizes the following technical solutions: a negative stiffness device for quasi-zero stiffness vibration isolation, the negative stiffness device comprising a ring-shaped inner ring, a ring-shaped outer ring and a negative stiffness mechanism combination; the negative stiffness mechanism is formed by vertically stacking a plurality of negative stiffness unit combinations. The negative stiffness unit combination is formed by continuously arranging a plurality of negative stiffness units in the same plane along the circumferential direction to form a ring-shaped ring, forming a multi-layer ring-shaped negative stiffness mechanism; each negative stiffness unit has a rotatable leaf spring, the two ends of the rotatable leaf spring are connected to rotatable nodes, and at least one of the rotatable nodes is a compressible elastic rotatable node; the rotatable leaf spring moves up and down under the action of the inner support block and the outer support block, and rotates around the rotatable node, gradually changes from a slope to a horizontal position, forming negative stiffness.

[0015] Further, the ring-shaped inner ring or the ring-shaped outer ring is respectively installed on the inner surface or the outer surface of the negative stiffness mechanism, wherein the ring-shaped outer ring is sleeved on the outside of the ring-shaped inner ring, a uniform gap is left between the ring-shaped inner ring and the ring-shaped outer ring, and the negative stiffness mechanism is installed in the gap; the ring-shaped inner ring or the ring-shaped outer ring is a moving part that is limited in horizontal movement but can move vertically upward and downward, and at least one of them is a moving part that can move vertically upward and downward; that is, the ring-shaped inner ring can move vertically upward and downward relative to the ring-shaped outer ring, but the two cannot move relative to the horizontal direction.

[0016] Further, the ring-shaped inner ring and the ring-shaped outer ring are ring-shaped structures, including a circular shape, a square shape or a polygonal shape; the inner supporting blocks and the outer supporting blocks of the negative stiffness unit are equally distributed around the gap of the ring-shaped inner ring and the ring-shaped outer ring.

[0017] Further, the rotatable sheet spring of the negative stiffness unit is clamped in the inner supporting block and the outer supporting block, and the inner supporting block and the outer supporting block are respectively connected with the ring-shaped inner ring or the ring-shaped outer ring to form an integrated structure; or a plurality of inner supporting blocks and outer supporting blocks are respectively embedded in the ring-shaped inner ring or the ring-shaped outer ring to form an embedded structure; and the inner supporting block and / or the outer supporting block are moving parts that move vertically upward and downward together with the ring-shaped inner ring and the ring-shaped outer ring.

[0018] Further, the rotatable sheet spring is a flat spring sheet, which is a rectangular sheet as a whole; the two ends of the rotatable sheet spring are rotatable ball heads, so that the length direction cross section of the rotatable sheet spring forms a dumbbell-shaped structure; the two ends of the sheet spring are connected to the outer surface of the inner supporting block and the inner surface of the outer supporting block, and the rotatable ball heads are clamped in the ball nests of the inner supporting block and the outer supporting block to form a rotatable node; the rotatable sheet spring can rotate upward and downward in the ball nests of the inner supporting block and the outer supporting block.

[0019] Further, the rotatable sheet spring is in an inclined arrangement state in the initial state of the inner supporting block and the outer supporting block; when the inner supporting block and the outer supporting block are installed in the damping system and move vertically upward and downward relative to each other, the rotatable sheet spring will gradually transition from the inclined state to the horizontal state with the vertical movement of the inner supporting block and the outer supporting block relative to each other, and the vertical component force will change continuously during the transition from the inclined state to the horizontal state, thereby forming a negative stiffness through the vertical component force of the two ends of the sheet spring supported by the inner supporting block and the outer supporting block, and the negative stiffness gradually decreases and gradually tends to zero, thereby forming a quasi-zero stiffness change of the negative stiffness.

[0020] Further, the rotatable ball head at both ends of the rotatable leaf spring is connected with the ball cavity of the inner supporting block and the outer supporting block through the elastic supporting sheet; the rotatable ball head is wrapped by the elastic supporting sheet, and then is clamped into the ball cavity of the inner supporting block and the outer supporting block to form a rotating joint.

[0021] Further, the rotatable leaf spring is a flexural spring leaf, and when the leaf spring moves vertically on the inner supporting block and the outer supporting block, the leaf spring is deformed in flexure under the horizontal force, and the negative stiffness is adjusted by the flexural deformation of the leaf spring to meet the demand of the quasi-zero stiffness vibration isolation on the negative stiffness.

[0022] Further, the flexural spring leaf is in the shape of a rectangle, the width is 1 / 3-1 / 2 of the length, and the middle part of the length direction is slightly bent downward, and the both 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 1.3-1.8 times of the thickness of the spring leaf, and the end cylindrical surface is circularly arc transitioned with the upper and lower surfaces in the thickness direction of the spring leaf. Preferably, 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.

[0023] Further, the compressible elastic rotating joint is an elastic rubber composite, a rubber layer is arranged between the elastic supporting sheet and the ball cavity of the inner supporting block and the outer supporting block, the rubber layer is vulcanized on the inner supporting block or the outer supporting block, and the elastic supporting sheet is further vulcanized on the rubber layer, the rubber layer is compressed by the elastic supporting sheet to form the elastic rotating joint, the elastic supporting sheet is an arc-shaped elastic sheet, the middle part of the elastic supporting sheet is an arc-shaped pit, the arc of the arc-shaped pit is matched with the arc of the rotatable ball head of the rotatable leaf spring, the arc-shaped pit of the elastic supporting sheet is in contact with the end of the leaf spring, and the rotatable cooperation is formed.

[0024] Further, a wear-resistant pad is arranged between the elastic supporting sheet and the rotatable ball head of the rotatable leaf spring, and the rotatable ball head is wrapped by the wear-resistant pad, and the rotating friction between the elastic supporting sheet and the rotatable ball head is reduced through the wear-resistant pad.

[0025] The beneficial effects of the present application are as follows:

[0026] The rotatable leaf spring is adopted in the present application, the negative stiffness is formed by changing the force of the leaf spring and the rotating joint, the negative stiffness matched with the quasi-zero stiffness vibration isolation requirement is realized, the demand of the quasi-zero stiffness vibration isolation on the negative stiffness is solved, the structure is simple, the production is easy, the batch production is realized, the deficiencies of the existing vibration isolator, such as complex installation and difficult maintenance, are solved, and the engineering application conditions are completely met.

[0027] 1. Replacing conventional piston rods, disc springs, or linear springs with rotatable leaf springs eliminates the unstable and uneven stress caused by vertical forces when the negative stiffness of piston rods is formed. It also solves the problem of torsional deformation when the negative stiffness of disc springs is formed, preventing uneven stress in various directions and torsional deformation.

[0028] 2. 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.

[0029] 3. 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.

[0030] 4. 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.

[0031] 5. 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.

[0032] 6. 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. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present invention;

[0034] Figure 2 For the appendix Figure 1 A schematic diagram of a multi-layered negative stiffness mechanism;

[0035] Figure 3 This is a schematic diagram of the negative stiffness unit of the present invention;

[0036] Figure 4 for Figure 3 A partially enlarged structural diagram;

[0037] Figure 5 A displacement diagram of a leaf spring of the present application;

[0038] Figure 6 A schematic diagram of a negative stiffness unit plane arrangement of embodiment one;

[0039] Figure 7 A schematic diagram of a cover plate structure of the negative stiffness device of embodiment one;

[0040] Figure 8 A deformation curve diagram of embodiment one;

[0041] Figure 9 A schematic diagram of a leaf spring plane arrangement of another embodiment of the present application;

[0042] Figure 10 A schematic diagram of a leaf spring plane arrangement of another embodiment of the present application. DETAILED DESCRIPTION

[0043] The present application will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0044] As known to those skilled in the art, the system has a vibration isolation effect only when the excitation frequency is greater than the inherent frequency by √2 times. The compression amount (static displacement at the equilibrium position) of the isolator in the vibration isolation system is limited by the installation space and the requirement for lateral stability, so the isolator needs to have high stiffness to improve the carrying capacity, but high stiffness inevitably leads to high inherent frequency. The contradiction between high carrying capacity and low inherent frequency has become a bottleneck for the development of passive vibration isolation technology, and low-frequency vibration isolation, especially low-frequency vibration isolation of heavy equipment, has always been a difficult problem in passive vibration isolation.

[0045] The isolator with high static and low dynamic stiffness has a stiffness that changes with the compression amount. At zero load, the isolator has large static stiffness (carrying stiffness) to ensure high carrying capacity and small static displacement. When the load compresses the isolator to the static equilibrium position, the dynamic stiffness of the isolator is greatly reduced. Therefore, such an isolator takes into account high carrying capacity and low inherent frequency, effectively solving the bottleneck problem of passive vibration isolation. The quasi-zero stiffness isolator is a very representative isolator with high static and low dynamic stiffness characteristics. As the name implies, the quasi-zero stiffness isolator is an isolator with dynamic stiffness close to zero. At least one negative stiffness device is required to achieve quasi-zero stiffness by connecting a negative stiffness mechanism in parallel to a positive stiffness system, and negative stiffness is generated by the negative stiffness device to offset the vibration generated by positive stiffness. The key role of negative stiffness is to connect a negative stiffness mechanism in parallel to a positive stiffness system to achieve quasi-zero stiffness.

[0046] Currently, the idea of connecting negative stiffness mechanism to positive stiffness system in parallel to achieve quasi-zero stiffness is many, but most of them are theoretical research; The negative stiffness device for quasi-zero stiffness vibration isolation proposed in the application is an engineering application capable negative stiffness device, especially a negative stiffness device capable of being applied to the narrow space of a tunnel lamp.

[0047] The negative stiffness device relates to an inner bearing part (2), an outer bearing part (1) and a negative stiffness mechanism (3), as shown in the accompanying drawings. Figures 1-9 The negative stiffness mechanism (3) is formed by vertically stacking a plurality of negative stiffness unit combinations (6), and the negative stiffness unit combination (6) is formed by continuously arranging a plurality of negative stiffness units (7) in the same plane in the circumferential direction to form a ring. A plurality of ring-shaped negative stiffness unit combinations (6) are stacked together to form a multi-layer ring-shaped negative stiffness mechanism. The core is the negative stiffness unit (7), each negative stiffness unit (7) has a rotatable leaf spring (12), the two ends of the rotatable leaf spring (12) are connected to the rotatable nodes (19), and at least one rotatable node (19) is an elastic compressible rotating node; The rotatable nodes (19) at both ends of the rotatable leaf spring (12) are arranged in the upper support block (8) and the lower support block (16), and move up and down with the upper support block (8) and the lower support block (16). The rotatable node (19) drives the rotatable leaf spring (12) to move up and down, and rotates around the rotatable node (19), and the shape of the rotatable leaf spring (12) gradually changes from a slope to a horizontal position, forming negative stiffness.

[0048] The inner bearing part (2) or the outer bearing part (1) is respectively arranged on the inner surface or the outer surface of the negative stiffness mechanism (3), wherein the outer bearing part (1) is sleeved on the inner bearing part (2), and a uniform gap is left between the inner bearing part (2) and the outer bearing part (1), and the negative stiffness mechanism is arranged and installed in the gap; The inner bearing part (2) or the outer bearing part (1) is a moving part that can move vertically but cannot move horizontally, and at least one of them is a moving part that can move vertically; That is, the inner bearing part (2) can move vertically relative to the outer bearing part (1), but the two cannot move horizontally relative to each other.

[0049] The inner bearing part (2) and the outer bearing part (1) are ring-shaped structures, including circular, square or polygonal; The upper support block (8) and the lower support block (16) of the negative stiffness unit (7) are equally distributed in the circumferential direction around the gap of the ring-shaped inner ring and the ring-shaped outer ring according to the shape of the ring-shaped inner ring and the ring-shaped outer ring.

[0050] The rotatable leaf spring (12) of the negative stiffness unit (7) is clamped in the upper support block (8) and the lower support block (16) through the rotatable node (19), and the upper support block (8) and the lower support block (16) are connected together with the inner bearing part (2) or the outer bearing part (1) respectively. The upper support block (8) and the lower support block (16) can be an integrated structure connected together with the inner bearing part (2) or the outer bearing part (1); or a plurality of upper support blocks (8) and lower support blocks (16) are embedded in the inner bearing part (2) or the outer bearing part (1) circumferentially respectively, forming an embedded structure with the inner bearing part (2) or the outer bearing part (1); and the upper support block (8) and / or the lower support block (16) are moving parts vertically following the inner bearing part (2) and the outer bearing part (1) respectively.

[0051] The rotatable leaf spring (12) is a flat spring leaf, which is in the shape of a rectangle as a whole; the two ends of the rotatable leaf spring (12) are rotatable cylindrical surfaces, so that the length direction cross section of the rotatable leaf spring (12) forms a dumbbell structure; the two ends of the rotatable leaf spring (12) are connected to the outer surface of the upper support block (8) and the inner surface of the lower support block (16) through the rotatable node (19), and the rotatable cylindrical surfaces are clamped in the ball cavity of the inner support block and the outer support block to form a rotatable node; the rotatable leaf spring (12) can rotate up and down in the ball cavity of the upper support block (8) and the lower support block (16).

[0052] The rotatable leaf spring (12) is a flexural spring leaf, which is in the shape of a rectangle as a whole, the width of which is 1 / 3-1 / 2 of the length, and the middle part of the length direction is slightly curved downward, the rotatable cylindrical surfaces are cylindrical surfaces with the width direction as the axis arranged at the two ends of the length direction, the radius of the cylindrical surface is about 1.3-1.8 times of the thickness of the spring leaf, and the end cylindrical surfaces are circularly arc transitioned with the upper and lower surfaces of the thickness direction of the spring leaf. Preferably, the length (L) of the rotatable leaf spring (12) is 14-25 mm; the thickness is 0.6-1 mm; the initial angle (A) of the inclination of the rotatable leaf spring (12) is between 15-25 degrees, and the up and down moving distance H is 1-5 mm.

[0053] The rotatable cylindrical surfaces of the two ends of the rotatable leaf spring (12) and the ball cavities of the upper support block (8) and the lower support block (16) are connected through the upper support spring leaf (11) and the lower support spring leaf (13); the rotatable cylindrical surfaces are clamped into the ball cavities of the upper support block (8) and the lower support block (16) by being clamped by the upper support spring leaf (11) and the lower support spring leaf (13) in a columnar shape, forming a rotating node.

[0054] The rotatable leaf spring (12) is a flexural spring leaf. The rotatable leaf spring (12) is vertically moved up and down on the upper supporting block (8) and the lower supporting block (16). With the change from the inclined shape to the horizontal shape of the rotatable leaf spring (12), the flexural deformation occurs under the horizontal force. The flexural deformation of the rotatable leaf spring (12) adjusts the size of the negative stiffness to adapt to the demand of the quasi-zero stiffness vibration isolation for the negative stiffness.

[0055] The elastic rotating node is an elastic rubber composite. The upper supporting rubber part (9) and the lower supporting rubber part (15) are respectively arranged between the upper supporting spring leaf (11) and the lower supporting spring leaf (13) and the ball nest of the upper supporting block (8) and the lower supporting block (16). The upper supporting rubber part (9) and the lower supporting rubber part (15) are respectively vulcanized on the upper supporting block (8) or the lower supporting block (16). The upper supporting spring leaf (11) and the lower supporting spring leaf (13) are respectively vulcanized on the upper supporting rubber part (9) and the lower supporting rubber part (15). The rotatable node (19) of the elastic body base is formed by compressing the rubber layer through the upper supporting spring leaf (11) and the lower supporting spring leaf (13). The upper supporting spring leaf (11) and the lower supporting spring leaf (13) are deformable arc-shaped spring leaves. The middle part of the upper supporting spring leaf (11) and the lower supporting spring leaf (13) is an arc-shaped concave pit. The arc of the arc-shaped pit is matched with the arc of the rotatable cylindrical surface of the rotatable leaf spring (12). The arc-shaped pit of the upper supporting spring leaf (11) and the lower supporting spring leaf (13) is in contact with the end of the rotatable leaf spring (12) and forms the rotatable node (19).

[0056] The wear-resistant pad is arranged between the upper supporting spring leaf (11) and the lower supporting spring leaf (13) and the rotatable cylindrical surface of the rotatable leaf spring (12). The wear-resistant pad wraps the rotatable ball head. The rotating friction between the elastic supporting leaf and the rotatable ball head is reduced through the wear-resistant pad. Preferably, the oil-containing bearing bush is used as the wear-resistant pad.

[0057] The working principle of the negative stiffness device is as follows. The rotatable leaf spring (12) is arranged in an inclined shape in the initial state of the upper supporting block (8) and the lower supporting block (16). When the upper supporting block (8) and the lower supporting block (16) are installed in the vibration reduction system, the rotatable leaf spring (12) moves up and down and rotates with the rotatable node (19) in the upper supporting block (8) and the lower supporting block (16) when the upper supporting block (8) and the lower supporting block (16) are vertically moved up and down. The vertical movement gradually changes from the inclined shape to the horizontal shape. The size of the vertical component force is continuously changed in the process of changing from the inclined shape to the horizontal shape. The negative stiffness is formed through the vertical component force of the two ends of the leaf spring and the inner supporting block and the outer supporting block. The negative stiffness gradually decreases and tends to be zero, and the quasi-zero stiffness change of the negative stiffness is formed.

[0058] The inventors are professional engineering technicians who have long been engaged in the research of elastic damping elements and have also conducted serious research on quasi-zero stiffness vibration isolation. According to the principle of the above technical solution, various technical implementation solutions are researched. Through comparison and analysis of multiple solutions, some relatively ideal implementation technical solutions are proposed. Example one

[0059] The embodiment is a circular ring-shaped quasi-zero stiffness vibration isolation negative stiffness device for urban rail transit. The quasi-zero stiffness vibration isolation negative stiffness device is composed of an outer bearing component (1), an inner bearing component (2), a negative stiffness mechanism (3), and an upper cover plate (4), as shown in the accompanying drawings. Figures 1-9 As shown.

[0060] The outer bearing component (1) is a stepped cylindrical barrel structure with a large upper end and a small lower end in the axial direction. The upper end cavity is a stepped hole structure, and an internal thread is arranged near the end position. The upper end cavity is coaxially installed with the inner bearing component (2), the negative stiffness mechanism (3), and the upper cover plate (4), respectively. An external thread is arranged on the outer cylinder of the lower end and forms an assembly relationship with the internal thread of the upper end of the stepped hole in the center of the upper cover bearing cylinder of the positive stiffness assembly (not shown in the figure).

[0061] The inner bearing component (2) is a barrel structure, the outer diameter of the barrel bottom is larger than the outer diameter of the barrel and forms a shaft shoulder, and a center hole is opened in the barrel bottom. The center hole and the hole end face form an assembly relationship with the stepped shaft of the top end of the center shaft pin arranged on the bottom plate of the positive stiffness assembly. The inner bearing component (2) is coaxially installed at the bottom of the upper end cavity of the outer bearing component (1). The negative stiffness mechanism (3) is coaxially installed between the upper end cavity of the outer bearing component (1) and the barrel of the inner bearing component (2).

[0062] The upper cover plate (4) is a cylindrical pie structure, and an external thread is arranged on the outer cylinder and forms an assembly relationship with the internal thread arranged on the upper end cavity of the outer bearing component (1). The lower end face of the upper cover plate (4) forms an assembly relationship with the outer circle top face (5) of the negative stiffness mechanism (3).

[0063] The negative stiffness mechanism (3) is composed of multiple negative stiffness unit combinations (6) stacked in the vertical direction, and each negative stiffness unit combination (6) is composed of multiple negative stiffness units (7) arranged in a circle in the same plane.

[0064] The negative stiffness unit (7) comprises an upper supporting block (8), an upper supporting rubber piece (9), an upper supporting copper tile (10), an upper supporting spring piece (11), a rotatable spring piece (12), a lower supporting spring piece (13), a lower supporting copper tile (14), a lower supporting rubber piece (15), and a lower supporting block (16). The upper supporting block (8), the upper supporting rubber piece (9), and the upper supporting spring piece (11) are integrally bonded and vulcanized; the lower supporting spring piece (13), the lower supporting rubber piece (15), and the lower supporting block (16) are integrally bonded and vulcanized; the upper supporting spring piece (11), the upper supporting copper tile (10), the lower supporting spring piece (13), and the lower supporting copper tile (14) are respectively connected with the end cylindrical surfaces of the two ends of the rotatable spring piece (12) to form rotatable nodes (19).

[0065] The rotatable spring piece (12) is a rectangular buckling spring piece, the width of which is about half of the length (L), and the middle part of the length direction is slightly bent downward, the two ends of the length direction are provided with cylindrical surfaces with the width direction as the axis, the radius of the cylindrical surface is about 1.5 times the thickness of the spring piece, and the end cylindrical surface is circularly transitioned with the upper and lower surfaces of the thickness direction of the spring piece. An inclined angle (A) is arranged between the length direction of the rotatable spring piece (12) and the horizontal plane, the cylindrical surfaces of the two ends form upper and lower joint supporting surfaces, and the copper tiles, i.e., the upper supporting copper tile (10) and the lower supporting copper tile (14), are wrapped on the cylindrical surfaces of the two ends.

[0066] The upper supporting spring piece (11) is a spring piece with the width consistent with that of the rotatable spring piece (12) and the length direction bent into an arch shape, and the cylindrical concave surface of the middle part forms a pair of friction pair connections with the upper supporting copper tile (10) of the rotatable spring piece (12).

[0067] The lower supporting spring piece (13) is a spring piece with the width consistent with that of the rotatable spring piece (12) and the length direction bent into an arch shape, and the cylindrical concave surface of the middle part forms a pair of friction pair connections with the lower supporting copper tile (14) of the rotatable spring piece (12).

[0068] The upper supporting block (8) is a load-bearing component allowing only up-down movement, the lower left direction of which is designed into an arch-shaped concave surface, which forms a corresponding matching relationship with the arch-shaped convex surface of the upper supporting spring piece (11), and the gap reserved between the arch-shaped concave surface of the upper supporting block (8) and the arch-shaped convex surface of the upper supporting spring piece (11) is filled with the upper supporting rubber piece (9) and integrally bonded and vulcanized together.

[0069] The lower supporting block (16) is a bearing component placed on the base platform, which is limited in horizontal movement, and the upper right direction is designed as an arc-shaped concave surface, which corresponds to the arc-shaped convex surface of the lower supporting spring sheet (13). The gap between the arc-shaped concave surface of the lower supporting block (16) and the arc-shaped convex surface of the lower supporting spring sheet (13) is filled with the lower supporting rubber piece (15) and integrally bonded and vulcanized together.

[0070] The working principle of the negative stiffness unit is that the upper supporting block (8) and the lower supporting block (16) are limited in horizontal movement and combined with the remaining elastic components to form an integral whole through rubber bonding and vulcanization. The lower supporting block (24) is placed on the base platform, and when the upper supporting block (8) is subjected to vertical loading, it will produce vertical displacement. Under the action of the loading force, the force transmission path is: upper supporting block (8)→upper supporting rubber piece (9)→upper supporting spring sheet (11)→upper supporting copper tile (10)→rotatable spring sheet (12)→lower supporting copper tile (14)→lower supporting spring sheet (13)→lower supporting rubber piece (15)→lower supporting block (16), wherein the rubber piece produces elastic compression deformation, the metal spring sheet produces elastic buckling deformation, and the angle (A) between the length direction of the rotatable spring sheet (12) and the horizontal plane changes from large to small. Preferably, the angle (A) is controlled between 15-30 degrees. In the case of continuous loading, when the angle (A) between the length direction of the rotatable spring sheet (12) and the horizontal plane is zero, the vertical force acting on the upper supporting block (8) and the displacement form a stiffness curve similar to a parabola; as shown in the accompanying Figure 10

[0071] As shown in the figure: the negative stiffness device includes a plurality of negative stiffness units (7), wherein the lower supporting block (16) of the negative stiffness unit (7) is designed as a circular ring, i.e. the inner ring (17) of the lower supporting block (16) of the negative stiffness device; the upper supporting block (8) of the negative stiffness unit is designed as a circular ring, i.e. the outer ring (18) of the upper supporting block (8) of the negative stiffness device; the rotatable spring sheet (12) in the negative stiffness unit is uniformly arranged in a circumferential direction to form a rotating spring sheet, and the lower supporting copper tile (14) and the upper supporting copper tile (10) and the upper supporting spring sheet (11) and the lower supporting spring sheet (13) are combined through the rubber ring formed by the upper rubber piece (9) and the lower supporting rubber piece (15) to be integrally bonded and vulcanized with the inner ring groove (21) of the lower supporting block (16) and the outer ring groove (22) of the upper supporting block (8), i.e. to form the negative stiffness device.

[0072] ​As shown in the figure: the upper cover plate (4) is a cylindrical pie structure, and a counterbore is formed in the upper end face, a nut is welded at the center position of the counterbore, and the outer cylinder of the nut is provided with external threads and is in assembly relationship with the internal threads provided on the upper end inner cavity of the outer bearing part (1). The lower end face of the upper cover plate (4) is in assembly relationship with the top face of the upper supporting block (8), and the gap between the two is controlled to be the distance of the mutual up-and-down movement of the upper supporting block (8) and the lower supporting block (16).

[0073] In summary, the beneficial effects of the embodiment are: the quasi-zero stiffness vibration isolator is arranged on the existing floating track bed, the quasi-zero stiffness vibration isolator is used to replace the steel spring or rubber spring vibration isolator in the existing track bed plate, the dynamic stiffness is low or tends to be zero in the static balance state, the problem of isolating low-frequency or ultra-low-frequency vibration in the traditional linear vibration isolation system is solved, the initial vibration isolation frequency is reduced, the vibration isolation frequency range is increased, and the system vibration isolation efficiency is improved. At the same time, the carrying capacity and reliability of the existing floating plate vibration reduction track are completely retained. Embodiment two

[0074] The basic principle of embodiment two is the same as that of embodiment one, but the structure is slightly different from that of embodiment one, as shown in the drawing; it is a square structure ring-shaped quasi-zero stiffness vibration isolation negative stiffness device; it comprises an outer bearing part (21), an inner bearing part (22), a negative stiffness mechanism (23) and an upper cover plate (24); the feature is that the outer bearing part (21) and the inner bearing part (22) are both square structure ring-shaped rings, and the inner bearing part (22), the negative stiffness mechanism (23) and the upper cover plate (24) are installed in the square ring-shaped groove in the outer bearing part (21).

[0075] However, the negative stiffness mechanism (23) is composed of a plurality of negative stiffness unit combinations (26) stacked along the plumb direction, and each negative stiffness unit combination (26) is composed of a plurality of negative stiffness units (27) arranged in the same plane along the four directions around the inner surface of the outer bearing part (21) and the outer surface of the inner bearing part (22).

[0076] Each negative stiffness unit (27) has only a buckling leaf spring and a rotatable node, the two ends of the buckling leaf spring are spherical ball heads, and the two ends of the buckling leaf spring are hinged together with the elastic support pieces clamped in the outer bearing part (21) and the inner bearing part (22) to form a rotatable node; the buckling leaf spring rotates and buckles while moving up and down with the outer bearing part (21) and the inner bearing part (22), forming negative stiffness.

[0077] The other parts are adjusted as in the first embodiment. This embodiment only uses the flexural leaf spring combined with the rotating node. In the flexural leaf spring, the relative structure is changed more simply and is easier to implement. However, the flexural leaf spring is required to be higher because the negative stiffness is completely adjusted by the flexural deformation of the flexural leaf spring. Embodiment three

[0078] The basic principle of the third embodiment is the same as that of the first embodiment, but the structure is slightly different from that of the first embodiment. It is a negative stiffness device of a ring-shaped quasi-zero stiffness vibration isolation with a hexagonal structure. It comprises an outer bearing part (31), an inner bearing part (32), a negative stiffness mechanism (33), and an upper cover plate (34). The characteristic is that the outer bearing part (31) and the inner bearing part (32) are both hexagonal structure ring-shaped rings, and the inner bearing part (32), the negative stiffness mechanism (33), and the upper cover plate (34) are installed in the hexagonal ring-shaped groove in the outer bearing part (31).

[0079] The negative stiffness mechanism (33) is composed of a plurality of negative stiffness unit combinations (36) stacked along the plumb direction, and each negative stiffness unit combination (36) is composed of a plurality of negative stiffness units (37) arranged in the same plane along the six surfaces of the inner surface of the outer bearing part (31) and the outer surface of the inner bearing part (32).

[0080] Each negative stiffness unit (37) is composed of a rigid leaf spring and an elastic rotatable node. The two ends of the rigid leaf spring are spherical ball heads, and the two ends of the rigid leaf spring are hinged together with the elastic support sheet clamped in the outer bearing part (31) and the inner bearing part (32). The elastic support sheet is bonded to the outer bearing part (31) and the inner bearing part (32) through an elastic rubber layer, forming an elastic rotatable node. The rigid leaf spring only rotates at the hinge point of the elastic support sheet during the up and down movement of the outer bearing part (31) and the inner bearing part (32), without flexural deformation. Instead, the rubber layer of the elastic rotatable node at both ends is compressed to compensate for the change in length of the rigid leaf spring in the horizontal direction, so that the force and direction of the two ends of the rigid leaf spring change, forming negative stiffness.

[0081] The other parts are adjusted as in the first embodiment. This embodiment only uses the flexural leaf spring combined with the rotating node. In the flexural leaf spring, the relative structure is changed more simply and is easier to implement. However, the flexural leaf spring is required to be higher because the negative stiffness is completely adjusted by the flexural deformation of the flexural leaf spring. Embodiment four

[0082] The basic principle of the embodiment four is the same as that of the embodiment one, but the structure is slightly different from that of the embodiment one; it is a circular structure annular quasi-zero stiffness vibration isolation negative stiffness device; it comprises an outer bearing part (41), an inner bearing part (42), a negative stiffness mechanism (43) and an upper cover plate (44); the feature is that the outer bearing part (41) and the inner bearing part (42) are both circular structure annular rings, and the inner bearing part (42), the negative stiffness mechanism (43) and the upper cover plate (44) are installed in the circular annular groove in the outer bearing part (41).

[0083] The negative stiffness mechanism (43) is composed of a plurality of negative stiffness unit combinations (46) stacked along the plumb direction, and each negative stiffness unit combination (46) is composed of a plurality of negative stiffness units (47) arranged continuously in the circumferential direction of the inner surface of the outer bearing part (41) and the outer surface of the inner bearing part (42) in the same plane.

[0084] And each negative stiffness unit (47) 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.

[0085] The negative stiffness unit comprises an upper supporting block (48), an upper supporting rubber part (49), an upper supporting copper tile (410), an upper supporting spring leaf (411), a buckling leaf spring (412), a lower supporting spring leaf (413), a lower supporting copper tile (414) and a lower supporting block (416).

[0086] Among them, the upper supporting block (48), the upper supporting rubber part (49) and the upper supporting spring leaf (411) are vulcanized into a whole; the lower supporting spring leaf (413) is directly embedded in the lower supporting block (416).

[0087] The buckling leaf spring (412) is a rectangular spring leaf, the width of which is about half of the length (L), and the middle part of the length direction is slightly bent downward, and the two ends of the length direction are provided with cylindrical surfaces with the width direction as the axis, the radius of the cylindrical surface is about 1.5 times the thickness of the spring leaf, and the end cylindrical surface and the upper and lower surfaces of the spring leaf thickness direction are circularly transitioned. An inclined angle (A) is arranged between the length direction of the buckling leaf spring (412) and the horizontal plane, the cylindrical surfaces at both ends form upper and lower joint supporting surfaces respectively, and copper tiles, i.e. upper supporting copper tile (410) and lower supporting copper tile (414) are wrapped on the cylindrical surfaces at both ends.

[0088] The upper supporting spring piece (411) is an arch-shaped spring piece with a width consistent with the width of the leaf spring (412) and a length direction, and the cylindrical concave surface in the middle part forms a pair of friction pair connection with the upper supporting copper tile (410) of the leaf spring (412).

[0089] The lower supporting spring piece (413) is an arch-shaped spring piece with a width consistent with the width of the leaf spring (412) and a length direction, and the cylindrical concave surface in the middle part forms a pair of friction pair connection with the lower supporting copper tile (414) of the leaf spring (412).

[0090] The upper supporting block (48) is a bearing part allowing only up and down movement, and the lower left direction is designed as an arch-shaped concave surface, which forms a corresponding matching relationship with the arch-shaped convex surface of the upper supporting spring piece (411). The gap between the arch-shaped concave surface of the upper supporting block (48) and the arch-shaped convex surface of the upper supporting spring piece (411) is filled with the upper supporting rubber piece (49) and integrally bonded and vulcanized together.

[0091] The lower supporting block (416) is a bearing part placed on the base platform, which limits the horizontal movement, and the upper right direction is designed as an arch-shaped concave surface, which forms a corresponding matching relationship with the arch-shaped convex surface of the lower supporting spring piece (413). The arch-shaped convex surface of the lower supporting spring piece (413) is directly embedded in the arch-shaped concave surface of the lower supporting block (416), forming an elastic and rotatable node with one end being compressible.

[0092] The other parts are the same as in Example 1. This example only uses a leaf spring combined with an elastic and rotatable node with one end being compressible, which takes advantage of the bending deformation of the leaf spring and the compressibility of the elastic rubber. The combination of the two can better achieve the adjustment and change of negative stiffness. At the same time, the rigid rotatable node is used at one end of the leaf spring, which is conducive to processing and manufacturing, and facilitates mass production.

[0093] It should be noted that the above listed embodiments are only to clearly and completely describe the technical solutions of the present application in conjunction with the drawings; obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments, and the terms such as "upper", "lower", "front", "rear", "intermediate" and the like cited in the specification are only for the convenience of clear description, rather than to limit the scope of the present application, and the change or adjustment of the relative relationship without substantial change of the technical content is also regarded as the implementable scope of the present application. At the same time, the structure, proportion, size and the like shown in the drawings of the specification are only used to cooperate with the content disclosed in the specification for understanding and reading by those skilled in the art, and do not have technical significance to limit the implementable conditions of the present application, so any modification of the structure, change of the proportion relationship or adjustment of the size without affecting the effect and purpose that can be achieved by the present application should still fall within the scope of the technical content disclosed by the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0094] The beneficial effects of the present application are:

[0095] The present application adopts a rotatable leaf spring to form negative stiffness by changing the stress of the leaf spring and the rotating node, which not only realizes the negative stiffness matched with the quasi-zero stiffness vibration isolation requirement, solves the requirement of quasi-zero stiffness vibration isolation for negative stiffness, and has the following advantages:

[0096] 1. The rotatable leaf spring is used instead of the conventional piston rod or disc spring or linear spring, which not only eliminates the phenomenon that the piston rod type negative stiffness is easily affected by the vertical force to cause unstable stress and unevenness, but also solves the problem of torsional deformation of the disc spring negative stiffness, prevents uneven stress in all directions, and produces torsional deformation.

[0097] 2. The rotatable node is used to connect the rotatable leaf spring, so that the two ends of the rotatable leaf spring can rotate, so that the rotatable leaf spring can adjust the air attitude of the rotatable leaf spring during operation by rotating, effectively solving the problem that the piston type rod is easily stuck under the action of the vertical force; the air attitude of the rotatable leaf spring is adjusted by the rotation of the rotatable node to change the negative stiffness, and there is no sticking problem in the process, so the negative stiffness can truly realize the engineering application of quasi-zero stiffness vibration isolation.

[0098] 3. The elastic compressible structure of the rotatable node can compensate the size change of the rotatable leaf spring in the horizontal direction by compressing the elastic layer of the rotatable node when the rotatable leaf spring is rotated from the slope to the horizontal, thereby preventing the rotatable leaf spring from losing stability due to excessive horizontal force.

[0099] 4. The size of the negative stiffness can be accurately adjusted by the rotation and compression adjustment of the elastic rotatable node, thereby truly matching the positive stiffness of the quasi-zero stiffness vibration isolation system and truly realizing the quasi-zero stiffness vibration isolation.

[0100] 5. The rotatable leaf spring adopts the buckling leaf spring structure, and the negative stiffness can be formed by the directional deformation of the buckling leaf spring during the operation process, so that the required negative stiffness can be formed by the self change of the buckling rotatable leaf spring or the combination of the buckling rotatable leaf spring and the elastic rotatable node.

[0101] 6. The negative stiffness device has simple structure and stable and reliable implementation process, and can accurately determine the change rule of the negative stiffness, so as to find the accurate negative stiffness and its change rule required by the quasi-zero stiffness vibration isolation system, and truly realize the quasi-zero stiffness vibration isolation of the system.

Claims

1. A negative stiffness device for quasi-zero stiffness vibration isolation, the negative stiffness device comprising an inner ring, an outer ring, and a negative stiffness mechanism; characterized in that: The negative stiffness mechanism is formed by vertically stacking multiple negative stiffness units; the negative stiffness unit combination is formed by multiple negative stiffness units continuously arranged in a circular direction on the same plane to form a ring, forming a multi-layered ring-shaped negative stiffness mechanism; each negative stiffness unit has a rotatable leaf spring, the two ends of which are connected to rotatable nodes, and at least one of the rotatable nodes is a compressible elastic rotatable node; the rotatable leaf spring moves up and down under the action of the inner support block and the outer support block, and rotates around the rotatable node, gradually changing from an inclined plane to a horizontal plane to form negative stiffness; the rotatable leaf spring is a flat spring sheet, and the whole is rectangular in shape; the two ends of the rotatable leaf spring are rotatable ball heads, so that the cross-section of the rotatable leaf spring in the longitudinal direction forms a dumbbell-shaped structure; the two ends of the leaf spring are connected to the outer surface of the inner support block and the inner surface of the outer support block, and the rotatable ball heads are locked in the ball sockets of the inner support block and the outer support block to form rotatable nodes; the rotatable leaf spring can rotate up and down in the ball sockets of the inner support block and the outer support block.

2. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 1, characterized in that: The inner or outer ring is installed on the inner or outer surface of the negative stiffness mechanism, respectively. The outer ring is fitted over the inner ring, with a uniform gap between them. The negative stiffness mechanism is installed in the gap. The inner or outer ring is a movable component that restricts horizontal movement but can move vertically relative to each other, and at least one of them is a vertically movable component. That is, the inner ring can move vertically relative to the outer ring, but the two cannot move horizontally relative to each other.

3. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 2, characterized in that: The inner and outer rings of the ring shape are ring-shaped structures, including circles, squares, or polygons; the inner and outer support blocks of the negative stiffness unit are evenly distributed circumferentially around the gaps of the inner and outer rings of the ring shape.

4. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 1, characterized in that: The rotatable leaf spring of the negative stiffness unit is locked in the inner support block and the outer support block. The inner support block and the outer support block are respectively connected to the inner ring or the outer ring of the annular shape, forming an integral structure connected to the inner ring or the outer ring of the annular shape; or multiple inner support blocks and outer support blocks are respectively embedded in the inner ring or the outer ring of the annular shape in the circumferential direction, forming an embedded structure with the inner ring or the outer ring of the annular shape; moreover, the inner support block and / or the outer support block are moving parts that move vertically up and down together with the inner ring and the outer ring of the annular shape, respectively.

5. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 1, characterized in that: The rotatable leaf spring is initially arranged in an oblique shape with the inner and outer support blocks. When the inner and outer support blocks are installed in the vibration damping system and move vertically relative to each other with the positive stiffness unit, the rotatable leaf spring will gradually transition from an oblique shape to a horizontal shape as the inner and outer support blocks move vertically relative to each other. During the transition from an oblique shape to a horizontal shape, the magnitude of the vertical component force will continuously change. The negative stiffness will be formed by the vertical component force supported by the inner and outer support blocks at both ends of the leaf spring, and the negative stiffness will gradually decrease and gradually approach zero, forming a quasi-zero stiffness change of negative stiffness.

6. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 1, characterized in that: The rotatable ball heads at both ends of the rotatable leaf spring are connected to the ball sockets of the inner and outer support blocks through elastic support plates; the rotatable ball heads are wrapped by the elastic support plates and then inserted into the ball sockets of the inner and outer support blocks to form a rotation node.

7. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 6, characterized in that: The rotatable leaf spring is a buckling spring. As the inner and outer support blocks move vertically relative to each other, the leaf spring undergoes buckling deformation under the action of horizontal force as it transitions from an oblique shape to a horizontal shape. The negative stiffness is adjusted by the buckling deformation of the leaf spring to meet the negative stiffness requirements of quasi-zero stiffness vibration isolation.

8. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 7, characterized in that: The bending spring sheet is rectangular in shape, with a width of 1 / 3 to 1 / 2 of its length. 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.

9. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 1, characterized in that: The compressible elastic rotating joint is an elastic rubber composite. A rubber layer is provided between the elastic support plate and the ball socket of the inner and outer support blocks, and the rubber layer is vulcanized on the inner or outer support block. An elastic support plate is then vulcanized on the rubber layer, and the elastic support plate can compress the rubber layer to form a rotatable joint of the elastic body. The elastic support plate is a deformable arc-shaped spring sheet, and the middle part of the elastic support plate is an arc-shaped recess, the curvature of which matches the curvature of the rotatable ball head of the rotatable leaf spring. The arc-shaped recess of the elastic support plate contacts the end of the leaf spring and forms a rotatable fit.

10. The negative stiffness device for quasi-zero stiffness vibration isolation as described in claim 9, characterized in that: A wear-resistant pad is provided between the elastic support plate and the rotatable ball head of the rotatable plate spring, and the wear-resistant pad wraps around the rotatable ball head; the wear-resistant pad reduces the rotational friction between the elastic support plate and the rotatable ball head.

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