Tuned mass damper and seismic isolation method based on nitrogen spring-convex mechanism

Abstract

The present invention relates to a tuned mass damper and a seismic isolation method based on a nitrogen spring-convex mechanism, wherein the tuned mass damper comprises a ball screw flywheel structure, a convex spring structure and a nitrogen spring structure; the convex spring structure comprises a first spring, a center rod and a friction convex surface, the nitrogen spring structure comprises a sleeve and a nitrogen spring, the sleeve is fixed to the main structure, the center rod extends into the sleeve, the exposed portion of the center rod is connected to the ball screw flywheel structure through the first spring, the extended portion is provided with a friction convex surface, the nitrogen spring is fixed in the sleeve, the nitrogen spring comprises a roller, a cylinder and a piston rod, the cylinder is filled with nitrogen, a piston of a piston rod is provided in the cylinder, the rod body of the piston rod extends out of the cylinder, and the extended end of the rod body contacts the friction convex surface through the roller. Compared with the prior art, the present invention realizes adjustable negative stiffness, inertia mass efficiency, and damping energy consumption, thereby improving vibration isolation effect and frequency adjustment capability.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering and relates to a tuned mass damper based on a nitrogen spring-convex surface mechanism and a seismic isolation method. Background Art

[0002] Tuned mass dampers (TMDs) are a passive vibration absorption technology used in structural vibration control. Commonly used in civil and mechanical engineering, a TMD consists of a mass block, a tuned stiffness unit, and a damping unit. By setting the TMD's natural frequency close to the natural frequency of the controlled primary structure, resonant energy absorption and vibration control are achieved. However, existing passive TMDs suffer from issues such as errors in the predicted natural frequency of the controlled primary structure, machining errors in the tuned stiffness unit, and complex external excitation frequency components. The TMD's vibration control performance deteriorates under detuned conditions and low-frequency excitation, often requiring the addition of a larger tuning mass (larger inertia) and a longer tuning mass swing stroke to achieve optimal tuned vibration absorption.

[0003] Patent CN112160438A discloses a magnetic screw-type eddy current damper with a negative stiffness nonlinear energy well. The device comprises a spring mass system, an inertial mass system, an eddy current damping system, a negative stiffness system, and a support system. By introducing an inertial mass amplification mechanism, the physical counterweight of the damper is reduced, thereby improving the mass ratio of the device while reducing the net spring extension of the device's low-frequency structure. Furthermore, a negative stiffness nonlinear energy well element is introduced to achieve resonant energy capture over a wide frequency range. Although this patent incorporates both a negative stiffness mechanism and an inertial mass mechanism, the negative stiffness mechanism can only achieve a limited negative stiffness effect that gradually decreases with increasing displacement. The effective negative stiffness coefficient achieved by the permanent magnet mechanism is limited and cannot provide a multi-level adjustable negative stiffness effect. The effective operating frequency range is insufficient, making it difficult to meet the frequency correction requirements of the tuned mass damper under detuned conditions.

[0004] Patent CN111139730A discloses a low-frequency vertical tuned mass damper with a negative stiffness nonlinear energy well. This patent utilizes the nonlinearity of the attractive force between a moving permanent magnet group and a fixed permanent magnet group to give the device a negative stiffness nonlinear energy well characteristic. A ball screw-type inertia mechanism is used to amplify the equivalent vibration mass of the tuned mass damper, improving the damping effect of the tuned mass damper while solving the problem of excessive net spring elongation in ultra-low-frequency vertical tuned mass dampers. This patent combines the advantages of a nonlinear energy well and a tuned mass damper, broadening the control frequency band of the tuned mass damper. However, similar to the aforementioned patents, this patent uses electromagnetic elements to implement a negative stiffness mechanism. The negative stiffness it can provide decreases with increasing displacement, and it cannot provide customizable and enhanced negative stiffness. It also cannot provide stable load-bearing capacity or meet large deformation conditions.

[0005] Patent CN112343393A discloses an amplified negative stiffness friction damping wall, comprising a top steel plate, a bottom friction plate, side plates, a nested nitrogen spring assembly, a preloaded nitrogen spring, a polished rod, a linear bearing, a pressure transmission plate, a track wheel, a secondary lever system, a rotating rod, a friction plate, and a friction lining. The preloaded nitrogen spring's spring force is amplified by the secondary lever system, and this amplified force is then applied to the friction plate by the rotating rod. The friction lining embedded in the bottom of the friction plate generates friction with the bottom friction plate. When the damping wall undergoes relative displacement, the rotating rod generates a negative stiffness force along the horizontal component, thus creating negative stiffness damping. However, this patent relies solely on preloaded nitrogen springs to achieve negative stiffness. The multi-stage lever employed to adjust the direction of the negative stiffness control force and amplify its amplitude still represents a single mechanism for achieving negative stiffness. Furthermore, when used as a damping wall for additional damping and shock absorption in building structures, this device is physically large and must be located on the ground floor of a building.

[0006] Patent CN111942095A discloses a semi-active suspension for new energy vehicles that couples a magnetic levitation spring and an eddy current damper. The suspension comprises an eddy current damping generating structure, a magnetic levitation spring structure, and a magnetorheological fluid. The vehicle's weight is supported by the attractive force between a moving permanent magnet and a coiled permanent magnet fixed to a lower working cylinder. The suspension controls the current in the coiled permanent magnet and the excitation coil based on real-time feedback from an accelerometer mounted in the piston, varying the force between the coiled permanent magnet and the moving permanent magnet and the viscosity of the magnetorheological fluid, thereby achieving adjustable suspension stiffness and damping. When the vehicle is traveling on a harsh road surface, the induced current generated in the coiled permanent magnet can be recovered via an external circuit. However, this patent relies on a complex control circuit system to control the current in the coiled permanent magnet and the excitation coil to change stiffness, and fails to provide a compact, efficient negative stiffness coefficient and control force. Summary of the Invention

[0007] The purpose of the present invention is to overcome at least one of the defects of the above-mentioned prior art and to provide a tuned mass damper and seismic isolation method based on a nitrogen spring-convex mechanism. The present invention realizes adjustable negative stiffness, inertia mass efficiency, and damping energy consumption, thereby improving vibration isolation effect and frequency adjustment capability.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] One of the technical solutions of the present invention is to provide a tuned mass damper based on a nitrogen spring-convex mechanism, wherein the tuned mass damper includes a ball screw flywheel structure, a convex spring structure, and a nitrogen spring structure. The nitrogen spring structure is provided on the main structure, and the nitrogen spring structure is connected to the ball screw flywheel structure through the convex spring structure.

[0010] The convex spring structure includes a first spring, a center rod and a friction convex surface. The nitrogen spring structure includes a sleeve and a nitrogen spring. The sleeve is fixed to the main structure. The center rod extends into the sleeve. The exposed part of the center rod is connected to the ball screw flywheel structure through the first spring. The extended part is provided with a friction convex surface. The nitrogen spring is fixed in the sleeve. The nitrogen spring includes a roller, a cylinder and a piston rod. The cylinder is filled with nitrogen. A piston of the piston rod is provided in the cylinder. The rod body of the piston rod extends out of the cylinder. The extended end of the rod body contacts the friction convex surface through the roller. The convex structure of the nitrogen spring and the friction convex surface constitutes a nitrogen spring-convex mechanism composite negative stiffness unit.

[0011] As an optimal technical solution, the material of the center rod is selected from one or more of steel, aluminum alloy, and copper alloy, and has excellent processing performance; the material of the friction convex surface is selected from one or more of steel, cast iron, and copper alloy, and has excellent wear resistance.

[0012] As a preferred technical solution, at least one pair of friction convex surfaces is provided on the portion into which the central rod extends.

[0013] As a preferred technical solution, at least one pair of nitrogen springs is fixed in the sleeve.

[0014] When the main structure vibrates, i.e., produces vertical displacement, the ball screw flywheel structure also undergoes vertical displacement, and the first spring drives the center rod and the friction convex surface to displace. At this time, the convex spring structure and the nitrogen spring structure undergo vertical relative displacement, and the nitrogen spring-convex mechanism composite negative stiffness unit comes into play.

[0015] The central rod and the friction convex surface undergo vertical relative displacement with the nitrogen spring next to it. Due to the pre-compression design of the nitrogen spring and the convex structure design of the friction convex surface, the nitrogen spring next to it provides an auxiliary motion force in the same direction of displacement to the convex spring structure, thereby assisting and amplifying the movement of the tuned mass damper.

[0016] Furthermore, the nitrogen spring adopts a multi-stage nitrogen spring, which includes a roller and at least two stages of cylinders and piston rods. The cylinders are filled with nitrogen, and the pistons of the piston rods of the same stage are arranged in the cylinders of the same stage. The cylinders of the latter stage are arranged in the piston rods of the former stage. Except for the last stage, the pistons and rod bodies of the piston rods of other stages are all confined in the cylinders of the same stage. The piston of the piston rod of the last stage is confined in the cylinder of the last stage, and the rod body extends out of the cylinder of the last stage. The extended end of the rod body contacts the friction convex surface through the roller.

[0017] Furthermore, a hole is provided on the piston, and the cylinder of the same stage maintains the front and rear spaces divided by the piston of the piston rod of the same stage in communication through the hole. The cylinder of the next stage is connected to the cylinder of the previous stage through the hole when the pistons of the front and rear piston rods are not in contact. After the piston rod of the previous stage moves until the rod body of the piston rod of the previous stage contacts the cylinder of the previous stage, nitrogen enters the inner cavity of the piston rod through the hole to form the cylinder of the next stage, thereby forming a multi-stage locking nitrogen spring;

[0018] By utilizing the design that the cross-sectional area of ​​the piston rod body is smaller than that of the piston, and utilizing the difference in cross-sectional area between the rod body of the rear-stage piston rod and the piston compared to that of the front-stage piston rod, the different stages of the multi-stage nitrogen spring can provide adjustable preload for the convex structure, further optimizing the stiffness performance. The movement process of the convex spring structure is divided into two stages: in the initial stage, the preload of the multi-stage nitrogen spring is relatively large, and the friction convex surface and the center rod move synchronously without generating relative displacement; as the vertical relative displacement between the convex spring structure and the nitrogen spring structure increases, the preload gradually decreases, and the friction convex surface and the center rod move relative to each other, generating Coulomb friction on the contact surface and dissipating energy.

[0019] Furthermore, the ball screw flywheel structure and the main structure are connected in series through a convex spring structure and a nitrogen spring structure, and then connected in parallel with a spring. The spring provides positive stiffness, and the force of the nitrogen spring acting on the friction convex surface changes continuously with the vertical relative displacement of the convex spring structure and the nitrogen spring structure. The nitrogen spring-convex mechanism composite negative stiffness unit provides multi-stage nonlinear negative stiffness related to the displacement, and the stiffness of the tuned mass damper changes with the displacement, thereby achieving the characteristics of high static stiffness and low dynamic stiffness.

[0020] As a preferred technical solution, in the static state, the roller is located at the highest point of the friction convex surface. At this time, the nitrogen spring only provides horizontal preload, ensuring that the tuned mass damper has sufficient load-bearing capacity in the static state and preventing excessive deformation; in the dynamic state, the tuned mass damper significantly reduces the natural frequency and the displacement transmission rate by reducing the equivalent dynamic stiffness.

[0021] Since the stiffness of the nitrogen spring-convex mechanism composite negative stiffness unit changes with displacement, the tuned mass damper can realize the frequency adjustment function, thereby adapting to the changing vibration environment and improving performance stability and adaptability.

[0022] As a preferred technical solution, the ball screw flywheel structure and the main body structure are connected in series through a convex spring structure and a nitrogen spring structure, and then vertically connected in parallel with at least one pair of springs.

[0023] As a preferred technical solution, the springs are all linear springs, and the stiffness of the linear springs is a fixed value. The mechanical properties of the negative stiffness component can be more easily adjusted by selecting linear springs with different stiffnesses.

[0024] Furthermore, the ball screw flywheel structure includes a flywheel, a ball nut and a threaded screw. The flywheel is coaxially fixedly connected to the radial outer side of the ball nut. The flywheel and the ball nut are both sleeved on the threaded screw. When the main structure vibrates, that is, vertical displacement is generated, the ball screw flywheel structure undergoes vertical displacement, converting the vertical displacement into high-speed rotational motion of the flywheel, thereby generating inertia mass efficiency.

[0025] Furthermore, the ball screw flywheel structure also includes a limit block, the flywheel is embedded in the limit block, and the threaded screw extends into the limit block, limiting the flywheel from generating vertical displacement relative to the limit block and only allowing high-speed rotational movement. A screw limit plate is provided on the protruding end of the threaded screw, and a spring limit plate is provided on the exposed part of the center rod. The screw limit plate is connected to the spring limit plate through a first spring. While the limit plate serves as the installation position of the first spring, it limits the vertical relative displacement of the ball screw flywheel structure and the main structure.

[0026] As a preferred technical solution, the first spring is sleeved on the exposed portion of the center rod, and the two ends of the first spring are vertically fixedly connected to the screw limit plate and the spring limit plate respectively.

[0027] As an optimal technical solution, a limiting cylinder is provided under the limiting block, which extends into the sleeve. The first spring, center rod, screw limiting plate and spring limiting plate move in the limiting cylinder to limit the horizontal movement of these components.

[0028] Furthermore, a permanent magnet disc is arranged in the limit block, and the flywheel includes a conductor flywheel gear piece and a non-conductor flywheel gear piece arranged at intervals. The conductor flywheel gear piece and the non-conductor flywheel gear piece rotate at high speed, cutting the magnetic flux lines generated by the permanent magnet disc, forming an eddy current effect to consume energy.

[0029] As a preferred technical solution, the material of the conductive flywheel gear piece is selected from one or more of steel, aluminum alloy, and copper alloy, and has good electrical conductivity; the material of the non-conductive flywheel gear piece is selected from one or more of rubber, ceramic, and wood, and has good electrical insulation performance.

[0030] Furthermore, a group of permanent magnet discs are arranged in the limit block, namely a first permanent magnet disc and a second permanent magnet disc. The first permanent magnet disc and the second permanent magnet disc are respectively arranged on both sides of the flywheel. The N-level and S-level directions of the first permanent magnet disc and the second permanent magnet disc are the same. The first permanent magnet disc and the second permanent magnet disc generate vertical magnetic lines of force passing through the flywheel. At this time, the rotation of the flywheel will produce a change in magnetic flux and generate eddy current damping, thereby achieving an energy dissipation effect.

[0031] Furthermore, the permanent magnet disc includes permanent magnet disc teeth and non-conductor disc teeth that are arranged at intervals. When the first permanent magnet disc and the second permanent magnet disc are arranged relative to each other, since the permanent magnet disc teeth and non-conductor disc teeth are arranged alternately and there are vertical intervals between a group of permanent magnet discs, their magnetic field characteristics are affected by the arrangement structure, thereby forming an intermittent magnetic field distribution in the vertical direction.

[0032] As an optimal technical solution, the material of the permanent magnet disc tooth piece is selected from one or more of ferrite magnet, Ru-Fe-B, Al-Ni-Co, and has good ferromagnetic properties; the material of the non-conductor disc tooth piece is selected from one or more of rubber, ceramic, and wood, and has good magnetic insulation properties.

[0033] As a preferred technical solution, both ends of the spring are vertically fixedly connected to the limit block and the main structure respectively.

[0034] The tuned mass damper utilizes the synergistic effect of inertia, negative stiffness and friction energy dissipation to significantly improve vibration isolation effect and frequency adjustment capability.

[0035] One of the technical solutions of the present invention is to provide a seismic isolation method based on a nitrogen spring-convex mechanism, wherein the method uses the tuned mass damper to isolate the main structure, and the method comprises the following steps:

[0036] The convex spring structure has two processes. The first process: in the initial stage, the preload provided by the multi-stage nitrogen spring next to the center rod is large enough. Under the action of the preload of the multi-stage nitrogen spring next to the center rod, the friction convex surface next to the center rod moves together with the center rod without generating relative displacement. The second process: as the vertical relative displacement between the convex spring structure and the nitrogen spring structure gradually increases, the preload provided by the multi-stage nitrogen spring next to the center rod gradually decreases, and the friction convex surface next to the center rod moves relative to each other, generating Coulomb friction on the contact surface and dissipating energy through damping.

[0037] There are two stages in the movement of the nitrogen spring structure. The first stage: the cylinder and piston rod of the previous stage form the nitrogen spring of the previous stage, and the cross-sectional area of ​​the piston rod is smaller than the cross-sectional area of ​​the piston, thereby generating a pressure difference, which provides pre-stress for the convex spring structure; the second stage: as the piston rod of the previous stage moves to the end point, the inner cavity of the piston rod of the previous stage serves as the cylinder of the next stage, and nitrogen enters the cylinder of the next stage through the hole. The cylinder and piston rod of the next stage form the nitrogen spring of the next stage, and similarly, the cross-sectional area of ​​the piston rod is smaller than the cross-sectional area of ​​the piston, which provides pre-stress for the convex spring structure. The difference between the cross-sectional area of ​​the rod body and the piston of the next stage piston rod is different from the difference between the cross-sectional area of ​​the rod body and the piston of the previous stage piston rod, so different designable pre-stress effects can be provided for the convex spring structure;

[0038] The center rod and the adjacent multi-stage nitrogen spring and friction convex surface are connected to the ball screw flywheel structure through the first spring. The ball screw flywheel structure converts the vertical displacement of the threaded screw into the rotation of the ball nut, which in turn drives the flywheel to rotate, generating an inertia effect. The conductive flywheel gear pieces and non-conductive flywheel gear pieces of the flywheel rotate to cut the magnetic flux lines generated by the first permanent magnet disc and the second permanent magnet disc, forming an eddy current effect to damp and dissipate energy.

[0039] The ball screw flywheel structure is connected to the main structure through a convex spring structure, a nitrogen spring structure, and a spring. When the main structure vibrates, that is, a vertical displacement is generated, a relative displacement occurs between the ball screw flywheel structure and the main structure. The spring provides linear positive stiffness, and the nitrogen spring-convex mechanism composite negative stiffness unit composed of the convex structure of the nitrogen spring and the friction convex surface provides multi-stage nonlinear negative stiffness related to the displacement, thereby realizing flexible adjustment of the stiffness, and then realizing flexible adjustment of the vibration isolation frequency domain, making the application range of the tuned mass damper wider.

[0040] As a preferred technical solution, the difference in cross-sectional area between the rod body and the piston of the latter stage piston rod is greater than the difference in cross-sectional area between the rod body and the piston of the former stage piston rod, thereby providing a designable enhanced preload effect for the convex spring structure.

[0041] As a preferred technical solution, the difference in cross-sectional area between the rod body and the piston of the latter stage piston rod is smaller than the difference in cross-sectional area between the rod body and the piston of the former stage piston rod, thereby providing a designable reduced pre-stress effect for the convex spring structure.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The present invention utilizes the convex structure of the multi-stage nitrogen spring composite friction convex surface to achieve multi-stage adjustable negative stiffness mechanical characteristics; utilizes the pre-loaded nitrogen spring and the convex structure dual mechanism in parallel to provide a compact and efficient negative stiffness realization mechanism, and significantly enhances the reliability of the tuned mass damper of the nitrogen spring-convex mechanism; further utilizes multiple parallel-arranged positive stiffness tuning springs below the ball screw flywheel structure to achieve static load-bearing and dynamic frequency modulation functions, and utilizes the ball screw flywheel structure to achieve inertia mass efficiency and eddy current damping limit functions; utilizes the nitrogen spring-convex mechanism composite negative stiffness unit in series with the tuning spring and the ball screw flywheel structure, and then connects the tuning spring in parallel to form an adaptive tuned mass damping system that meets low-frequency tuning and frequency adjustment requirements;

[0044] (2) The present invention can achieve a multi-stage preload effect of a multi-stage nitrogen spring by designing the difference between the area of ​​the multiple piston rods and the pistons of the multi-stage nitrogen spring; by designing the center rod and the friction convex surfaces on both sides of the convex spring structure, a two-stage motion process is achieved, providing a multi-stage nonlinear negative stiffness design related to displacement. The Coulomb friction formed by the relative movement of the center rod and the friction convex surfaces on both sides in the second stage further enhances the energy dissipation capacity;

[0045] (3) The nitrogen spring-convex mechanism of the present invention has a multi-stage nonlinear negative stiffness design related to displacement. By being connected in parallel with multiple positive stiffness tuning springs, the positive stiffness, negative stiffness or quasi-zero stiffness of the device and its size can be adjusted in real time, further realizing flexible adjustment of structural stiffness, absorption and dissipation of vibration energy, and at the same time increasing the vibration isolation frequency domain, thereby achieving vibration isolation and frequency adjustment capabilities within a wider frequency domain;

[0046] (4) The ball screw flywheel structure of the present invention converts the vertical linear motion of the threaded screw into the rotational motion of the flywheel. By introducing the inertia principle, the physical counterweight is reduced while the mass ratio of the device is improved. At the same time, the rotation of the flywheel's conductor flywheel gear cuts the magnetic flux lines generated by a set of permanent magnet disks, forming an eddy current effect. The series-connected nitrogen spring-convex mechanism further promotes the vertical linear motion and rotational motion of the ball screw flywheel structure, thereby improving the energy consumption efficiency of the generated eddy current damping.

[0047] (5) The eddy current damping effect formed by the flywheel rotating and cutting the magnetic flux lines and the Coulomb friction damping effect formed by the relative displacement between the friction convex surface and the center rod of the present invention realize the integration of multiple damping effects;

[0048] (6) The present invention belongs to dynamic vibration absorption technology, and can provide low-frequency, mass-enhanced tuned vibration absorbers and enhanced isolation layers and their additional inertial vibration absorbers. It occupies a small space and has a more compact design, which can be applied to a variety of application scenarios. The present invention adopts a dual passive mechanical adjustment design of pre-stressed nitrogen springs and convex structures, which does not rely on complex active control systems, significantly improves the stability and operational reliability of the system, and does not require any external input of electrical energy, and can operate normally in any environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the front cross-sectional structure of a tuned mass damper based on a nitrogen spring-convex mechanism in an embodiment of the present invention;

[0050] Figure 2 Schematic diagram of the top view of the flywheel in an embodiment of the present invention;

[0051] Figure 3 Schematic diagram of the top view of the permanent magnet disk in an embodiment of the present invention;

[0052] Figure 4 Schematic diagram of the front cross-sectional structure of a multi-stage nitrogen spring in an embodiment of the present invention.

[0053] Description of the marks in the figure:

[0054] 1—ball screw flywheel structure, 2—convex spring structure, 3—nitrogen spring structure, 5—main body structure;

[0055] 11—first permanent magnet disc, 12—flywheel, 13—second permanent magnet disc, 14—ball nut, 15—threaded screw;

[0056] 111—permanent magnet disc gear piece, 112—non-conductor disc gear piece;

[0057] 121 - conductor flywheel gear, 122 - non-conductor flywheel gear;

[0058] 21 - first spring, 22 - center rod, 23 - first friction convex surface, 24 - second friction convex surface;

[0059] 31 - first multi-stage nitrogen gas spring, 32 - sleeve, 33 - second multi-stage nitrogen gas spring;

[0060] 311 - first cylinder, 312 - first piston rod, 313 - second piston rod, 314 - second cylinder, 315 - roller;

[0061] 41 - second spring, 42 - third spring, 43 - fourth spring, 44 - fifth spring. DETAILED DESCRIPTION

[0062] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0063] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like, used to describe common objects, merely refer to different instances of the same object and are not intended to imply that the objects described must be in a given order, whether temporally, spatially, sequentially, or in any other manner.

[0064] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0065] Example:

[0066] A tuned mass damper based on a nitrogen spring-convex mechanism, such as Figure 1 and Figure 4 As shown, it includes a ball screw flywheel structure 1, a convex spring structure 2 and a nitrogen spring structure 3. The nitrogen spring structure 3 is provided on the main structure 5, and the nitrogen spring structure 3 is connected to the ball screw flywheel structure 1 through the convex spring structure 2;

[0067] The convex spring structure 2 includes a first spring 21, a center rod 22 and a friction convex surface. The nitrogen spring structure 3 includes a sleeve 32 and a nitrogen spring. The sleeve 32 is fixed to the main structure 5. The center rod 22 extends into the sleeve 32. The exposed portion of the center rod 22 is connected to the ball screw flywheel structure 1 through the first spring 21. The extended portion is provided with a friction convex surface. The nitrogen spring is fixed in the sleeve 32. The nitrogen spring includes a roller 315, a cylinder and a piston rod. The cylinder is filled with nitrogen. A piston of the piston rod is provided in the cylinder. The rod body of the piston rod extends out of the cylinder. The extended end of the rod body contacts the friction convex surface through the roller 315. The convex structure of the nitrogen spring and the friction convex surface constitutes a nitrogen spring-convex mechanism composite negative stiffness unit.

[0068] The material of the center rod 22 is selected from one or more of steel, aluminum alloy, and copper alloy, and has excellent processing performance. In this embodiment, steel is preferably used;

[0069] The material of the friction convex surface is selected from one or more of steel, cast iron, and copper alloy, and has excellent wear resistance. In this embodiment, steel is preferably used;

[0070] At least one pair of friction convex surfaces is provided on the portion into which the center rod 22 extends. In this embodiment, a pair of two friction convex surfaces are provided horizontally opposite to each other on both sides of the portion into which the center rod 22 extends, namely a first friction convex surface 23 and a second friction convex surface 24.

[0071] The nitrogen spring is a multi-stage nitrogen spring. At least one pair of multi-stage nitrogen springs is fixed in the sleeve 32. In this embodiment, a pair of two multi-stage nitrogen springs are fixed horizontally at both ends of the sleeve 32, namely a first multi-stage nitrogen spring 31 and a second multi-stage nitrogen spring 33.

[0072] When the main structure 5 vibrates, i.e., produces vertical displacement, the ball screw flywheel structure 1 also undergoes vertical displacement, and the first spring 21 drives the center rod 22, the first friction convex surface 23, and the second friction convex surface 24 to displace. At this time, the convex spring structure 2 and the nitrogen spring structure 3 undergo vertical relative displacement, and the nitrogen spring-convex mechanism composite negative stiffness unit takes effect.

[0073] The central rod 22, the first friction convex surface 23, the second friction convex surface 24, and the first multi-stage nitrogen spring 31 and the second multi-stage nitrogen spring 33 on both sides undergo vertical relative displacement. Due to the preload design of the multi-stage nitrogen spring and the convex structure design of the friction convex surface, the first multi-stage nitrogen spring 31 and the second multi-stage nitrogen spring 33 on both sides jointly provide auxiliary motion force in the same direction of displacement to the convex spring structure 2, thereby assisting and amplifying the motion of the tuned mass damper.

[0074] The multi-stage nitrogen spring includes a roller 315 and at least two stages of cylinders and piston rods. The cylinders are filled with nitrogen. The pistons of the piston rods of the same stage are arranged in the cylinders of the same stage. The cylinders of the subsequent stage are arranged in the piston rods of the previous stage. The pistons and rod bodies of the piston rods of the other stages except the last stage are all confined in the cylinders of the same stage. The piston of the piston rod of the last stage is confined in the cylinder of the last stage. The rod body extends out of the cylinder of the last stage. The extended end of the rod body contacts the friction convex surface through the roller 315.

[0075] In this embodiment, the multi-stage nitrogen spring includes a roller 315 and two-stage cylinders and piston rods, namely a first cylinder 311 and a first piston rod 312, a second cylinder 314 and a second piston rod 313. The first cylinder 311 and the second cylinder 314 are filled with nitrogen. The piston of the first piston rod 312 is disposed in the first cylinder 311, the second cylinder 314 is disposed in the first piston rod 312, and the piston of the second piston rod 313 is disposed in the second cylinder 314. The piston and rod body of the first piston rod 312 are both confined in the first cylinder 311, the piston of the second piston rod 313 is confined in the second cylinder 314, and the rod body extends out of the second cylinder 314. The extended end of the rod body contacts the friction convex surface through the roller 315.

[0076] In this embodiment, the extended end of the second piston rod 313 of the first multi-stage nitrogen spring 31 contacts the first friction convex surface 23 via the roller 315, thereby connecting the first multi-stage nitrogen spring 31 to the first friction convex surface 23. The extended end of the second piston rod 313 of the second multi-stage nitrogen spring 33 contacts the second friction convex surface 24 via the roller 315, thereby connecting the second multi-stage nitrogen spring 33 to the second friction convex surface 24.

[0077] A hole is provided on the piston. The cylinder of the same stage keeps the front and rear spaces divided by the piston of the piston rod of the same stage connected through the hole. The cylinder of the next stage is connected with the cylinder of the previous stage through the hole when the pistons of the front and rear piston rods are not in contact. After the piston rod of the previous stage moves until the rod body of the piston rod of the previous stage contacts the cylinder of the previous stage, nitrogen enters the inner cavity of the piston rod through the hole to form the cylinder of the next stage, forming a multi-stage locking nitrogen spring;

[0078] In this embodiment, a hole is provided on the piston of the first piston rod 312, and the first cylinder 311 maintains the front and rear spaces divided by the piston of the first piston rod 312 in communication through the hole. A hole is provided on the piston of the second piston rod 313, and the second cylinder 314 maintains the front and rear spaces divided by the piston of the second piston rod 313 in communication through the hole. The second cylinder 314 is connected to the first cylinder 311 through the hole when the pistons of the first piston rod 312 and the second piston rod 313 are not in contact. After the first piston rod 312 moves until the rod body of the first piston rod 312 contacts the first cylinder 311, nitrogen enters the inner cavity of the first piston rod 312 through the hole to form the second cylinder 314, forming a two-stage locking nitrogen spring;

[0079] By utilizing the design that the cross-sectional area of ​​the piston rod is smaller than that of the piston, and utilizing the fact that the difference in cross-sectional area between the rod body of the rear piston rod and the piston is different from that of the front piston rod, the different stages of the multi-stage nitrogen spring can provide adjustable preload for the convex structure, further optimizing the stiffness performance. The movement process of the convex spring structure 2 is divided into two stages: in the initial stage, the preload of the multi-stage nitrogen springs on both sides is relatively large, and the friction convex surface and the center rod 22 move synchronously without generating relative displacement; as the vertical relative displacement between the convex spring structure 2 and the nitrogen spring structure 3 increases, the preload gradually decreases, and the friction convex surface and the center rod 22 generate relative motion, generating Coulomb friction on the contact surface and dissipating energy;

[0080] The ball screw flywheel structure 1 and the main structure 5 are connected in series via a convex spring structure 2 and a nitrogen spring structure 3, and then connected in parallel with a spring. The spring provides positive stiffness, and the force exerted by the nitrogen spring on the friction convex surface varies continuously with the vertical relative displacement of the convex spring structure 2 and the nitrogen spring structure 3. The nitrogen spring-convex mechanism composite negative stiffness unit provides multi-stage nonlinear negative stiffness related to the displacement, and the stiffness of the tuned mass damper varies with the displacement, thereby achieving the characteristics of high static stiffness and low dynamic stiffness.

[0081] In the static state, the roller 315 is located at the highest point of the friction convex surface. At this time, the nitrogen spring only provides horizontal preload, ensuring that the tuned mass damper has sufficient load-bearing capacity in the static state and preventing excessive deformation. In the dynamic state, the tuned mass damper significantly reduces the natural frequency and displacement transmissibility by reducing the equivalent dynamic stiffness.

[0082] In addition, because the stiffness of the nitrogen spring-convex mechanism composite negative stiffness unit changes with displacement, the tuned mass damper can achieve frequency adjustment function, thereby adapting to changing vibration environments and improving performance stability and adaptability;

[0083] The ball screw flywheel structure 1 and the main structure 5 are connected in series through the convex spring structure 2 and the nitrogen spring structure 3, and then at least one pair of springs are connected in parallel to form a vertical connection. In this embodiment, the ball screw flywheel structure 1 and the main structure 5 are connected in series through the convex spring structure 2 and the nitrogen spring structure 3, and then two pairs of four springs are connected in parallel to form a vertical connection, namely, a second spring 41, a third spring 42, a fourth spring 43, and a fifth spring 44.

[0084] The above-mentioned springs, i.e., the first spring 21, the second spring 41, the third spring 42, the fourth spring 43, and the fifth spring 44, are all linear springs. The stiffness of the linear springs is a fixed value, and the mechanical properties of the negative stiffness component can be more easily adjusted by selecting linear springs of different stiffnesses.

[0085] The ball screw flywheel structure 1 includes a flywheel 12, a ball nut 14, and a threaded screw 15. The flywheel 12 is coaxially fixedly connected to the radially outer side of the ball nut 14. The flywheel 12 and the ball nut 14 are both sleeved on the threaded screw 15. When the main structure 5 vibrates, that is, when vertical displacement occurs, the ball screw flywheel structure 1 also undergoes vertical displacement, converting the vertical displacement into high-speed rotational motion of the flywheel 12, thereby generating inertia mass efficiency.

[0086] The ball screw flywheel structure 1 also includes a limit block, the flywheel 12 is embedded in the limit block, and the threaded screw 15 extends into the limit block, limiting the flywheel 12 from generating vertical displacement relative to the limit block and only allowing high-speed rotational motion to occur. A screw limit plate is provided on the protruding end of the threaded screw 15, and a spring limit plate is provided on the exposed portion of the center rod 22. The screw limit plate is connected to the spring limit plate through a first spring 21. The limit plate serves as a mounting position for the first spring 21 and limits the vertical relative displacement of the ball screw flywheel structure 1 and the main structure 5.

[0087] The first spring 21 is sleeved on the exposed portion of the center rod 22, and both ends of the first spring 21 are vertically fixedly connected to the screw limit plate and the spring limit plate respectively;

[0088] A limiting cylinder is provided under the limiting block, and the limiting cylinder extends into the sleeve 32. The first spring 21, the center rod 22, the screw limiting piece and the spring limiting piece move in the limiting cylinder to limit the horizontal movement of these components.

[0089] like Figure 2 As shown, a permanent magnet disc is provided in the limit block, and the flywheel 12 includes a conductor flywheel gear piece 121 and a non-conductor flywheel gear piece 122 arranged at intervals. The conductor flywheel gear piece 121 and the non-conductor flywheel gear piece 122 rotate at high speed, cutting the magnetic flux lines generated by the permanent magnet disc, forming an eddy current effect to dissipate energy;

[0090] The material of the conductor flywheel gear piece 121 is selected from one or more of steel, aluminum alloy, and copper alloy, and has good electrical conductivity. In this embodiment, steel is preferably used;

[0091] The material of the non-conductive flywheel gear piece 122 is selected from one or more of rubber, ceramic, and wood, and has good electrical insulation performance. In this embodiment, rubber is preferred;

[0092] A group of permanent magnet discs are provided in the limit block, namely a first permanent magnet disc 11 and a second permanent magnet disc 13. The first permanent magnet disc 11 and the second permanent magnet disc 13 are respectively arranged on both sides of the flywheel 12. The N-level and S-level directions of the first permanent magnet disc 11 and the second permanent magnet disc 13 are the same. The first permanent magnet disc 11 and the second permanent magnet disc 13 generate vertical magnetic flux lines passing through the flywheel 12. At this time, the rotation of the flywheel 12 will produce a change in magnetic flux and generate eddy current damping, thereby achieving an energy dissipation effect.

[0093] In this embodiment, the first permanent magnet disc 11 is arranged on the upper side of the flywheel 12, the second permanent magnet disc 13 is arranged on the lower side of the flywheel 12, and the threaded screw 15 extends into the second permanent magnet disc 13. The N-stage of the first permanent magnet disc 11 and the second permanent magnet disc 13 are both facing upward, and the S-stage are both facing downward;

[0094] like Figure 3 As shown, the permanent magnet disk includes permanent magnet disk teeth 111 and non-conductor disk teeth 112 that are arranged at intervals. When the first permanent magnet disk 11 and the second permanent magnet disk 13 are arranged relative to each other, since the permanent magnet disk teeth 111 and the non-conductor disk teeth 112 are alternately arranged and there is a vertical interval between a group of permanent magnet disks, their magnetic field characteristics are affected by the arrangement structure, thereby forming an interval magnetic field distribution in the vertical direction.

[0095] The material of the permanent magnet disc gear piece 111 is selected from one or more of ferrite magnet, Ru-Fe-B, Al-Ni-Co, and has good ferromagnetic properties. In this embodiment, ferrite magnet is preferably used;

[0096] The material of the non-conductive disc tooth piece 112 is selected from one or more of rubber, ceramic, and wood, and has good magnetic insulation performance. In this embodiment, rubber is preferably used;

[0097] In this embodiment, the ends of the second spring 41, the third spring 42, the fourth spring 43 and the fifth spring 44 are respectively vertically fixedly connected to the limit block and the main structure 5;

[0098] The tuned mass damper utilizes the synergistic effect of inertia, negative stiffness and friction energy dissipation to significantly improve vibration isolation and frequency adjustment capabilities.

[0099] A seismic isolation method based on a nitrogen spring-convex mechanism uses the above-mentioned tuned mass damper to isolate the main structure. The specific steps are as follows:

[0100] The convex spring structure 2 has two processes. The first process: in the initial stage, the preload provided by the first multi-stage nitrogen spring 31 and the second multi-stage nitrogen spring 33 on both sides of the center rod 22 is sufficiently large. Under the action of the preload of the multi-stage nitrogen springs on both sides, the first friction convex surface 23 and the second friction convex surface 24 on both sides of the center rod 22 move together with the center rod 22 without generating relative displacement. The second process: as the vertical relative displacement of the convex spring structure 2 and the nitrogen spring structure 3 gradually increases, the preload provided by the first multi-stage nitrogen spring 31 and the second multi-stage nitrogen spring 33 on both sides gradually decreases, and the first friction convex surface 23 and the second friction convex surface 24 on both sides move relative to the center rod 22, generating Coulomb friction on the contact surface and dissipating energy through damping.

[0101] The movement of the nitrogen spring structure 3 has two stages. In the first stage, the first cylinder 311 and the first piston rod 312 form a first-stage nitrogen spring. The cross-sectional area of ​​the piston rod is smaller than the cross-sectional area of ​​the piston, thereby generating a pressure difference, thereby providing preload for the convex spring structure 2. In the second stage, as the first piston rod 312 moves to the right end point, the inner cavity of the first piston rod 312 serves as the second cylinder 314. Nitrogen enters the second cylinder 314 through the hole. The second cylinder 314 and the second piston rod 313 form a second-stage nitrogen spring. Similarly, the cross-sectional area of ​​the piston rod is smaller than the cross-sectional area of ​​the piston, thereby providing preload for the convex spring structure 2. The difference in cross-sectional area between the rod body of the second piston rod 313 and the piston is greater than the difference in cross-sectional area between the rod body of the first piston rod 312 and the piston, thereby providing a designable enhanced preload effect for the convex spring structure 2.

[0102] The center rod 22 and the first and second multi-stage nitrogen springs 31 and 33 on both sides, as well as the first and second friction convex surfaces 23 and 24, are connected to the ball screw flywheel structure 1 via the first spring 21. The ball screw flywheel structure 1 converts the vertical displacement of the threaded screw 15 into the rotation of the ball nut 14, thereby driving the flywheel 12 to rotate, generating an inertia effect. The conductive flywheel gear pieces 121 and the non-conductive flywheel gear pieces 122 of the flywheel 12 rotate to cut the magnetic flux lines generated by the first and second permanent magnet disks 11 and 13, forming an eddy current effect to damp and dissipate energy.

[0103] The ball screw flywheel structure 1 is connected to the main structure 5 through the convex spring structure 2 and the nitrogen spring structure 3, the second spring 41, the third spring 42, the fourth spring 43, and the fifth spring 44. When the main structure 5 vibrates, that is, when a vertical displacement occurs, a relative displacement occurs between the ball screw flywheel structure 1 and the main structure 5. The second spring 41, the third spring 42, the fourth spring 43, and the fifth spring 44 provide linear positive stiffness, and the nitrogen spring-convex mechanism composite negative stiffness unit composed of the convex structure of the nitrogen spring and the friction convex surface provides multi-stage nonlinear negative stiffness related to the displacement, thereby realizing flexible adjustment of the stiffness, and then realizing flexible adjustment of the vibration isolation frequency domain, making the tuned mass damper more widely applicable.

[0104] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A tuned mass damper based on a nitrogen spring-convex mechanism, characterized in that: The tuned mass damper comprises a ball screw flywheel structure (1), a convex spring structure (2) and a nitrogen spring structure (3); the nitrogen spring structure (3) is provided on the main structure (5), and the nitrogen spring structure (3) is connected to the ball screw flywheel structure (1) via the convex spring structure (2); The convex spring structure (2) includes a first spring (21), a center rod (22) and a friction convex surface. The nitrogen spring structure (3) includes a sleeve (32) and a nitrogen spring. The sleeve (32) is fixed to the main structure (5). The center rod (22) extends into the sleeve (32). The exposed portion of the center rod (22) is connected to the ball screw flywheel structure (1) through the first spring (21). The extended portion is provided with a friction convex surface. The nitrogen spring is fixed in the sleeve (32). The nitrogen spring includes a roller (315), a cylinder and a piston rod. Nitrogen is filled in the cylinder. A piston of the piston rod is provided in the cylinder. The rod body of the piston rod extends out of the cylinder. The extended end of the rod body contacts the friction convex surface through the roller (315). The nitrogen spring is a multi-stage nitrogen spring comprising a roller (315) and at least two stages of cylinders and piston rods; The ball screw flywheel structure (1) comprises a flywheel (12), a ball nut (14) and a threaded screw (15), wherein the flywheel (12) is coaxially fixedly connected to the radial outer side of the ball nut (14), and the flywheel (12) and the ball nut (14) are both sleeved on the threaded screw (15); The ball screw flywheel structure (1) further comprises a limit block, the flywheel (12) is embedded in the limit block, and the threaded screw (15) extends into the limit block; A permanent magnet disc is arranged in the limit block, and the flywheel (12) comprises a conductor flywheel gear piece (121) and a non-conductor flywheel gear piece (122) arranged at intervals, and the conductor flywheel gear piece (121) and the non-conductor flywheel gear piece (122) rotate to cut the magnetic flux lines generated by the permanent magnet disc.

2. A tuned mass damper based on a nitrogen spring-convex mechanism according to claim 1, characterized in that: The cylinder is filled with nitrogen, and the piston of the piston rod of the same level is arranged in the cylinder of the same level, and the cylinder of the next level is arranged in the piston rod of the previous level. The pistons and rod bodies of the piston rods of the other levels except the last level are all confined in the cylinder of the same level, and the piston of the piston rod of the last level is confined in the cylinder of the last level, and the rod body extends out of the cylinder of the last level, and the extended end of the rod body contacts the friction convex surface through the roller (315).

3. A tuned mass damper based on a nitrogen spring-convex mechanism according to claim 2, characterized in that: The piston is provided with a hole, and the cylinders of the same level maintain the front and rear spaces divided by the pistons of the piston rods of the same level in communication through the hole, and the cylinder of the next level is connected to the cylinder of the previous level through the hole when the pistons of the piston rods of the previous and next levels are not in contact; The difference in cross-sectional area between the rod body and the piston of the latter stage piston rod is different from that of the former stage piston rod.

4. The tuned mass damper based on the nitrogen spring-convex mechanism according to claim 1, characterized in that: The ball screw flywheel structure (1) and the main body structure (5) are connected in series via a convex spring structure (2) and a nitrogen spring structure (3), and then connected in parallel via a spring.

5. The tuned mass damper based on nitrogen spring-convex mechanism according to claim 1, characterized in that: A screw limit piece is provided on the extended end of the threaded screw (15), and a spring limit piece is provided on the exposed portion of the center rod (22), wherein the screw limit piece is connected to the spring limit piece via a first spring (21).

6. The tuned mass damper based on nitrogen spring-convex mechanism according to claim 1, characterized in that: A group of permanent magnet discs are arranged in the limit block, namely a first permanent magnet disc (11) and a second permanent magnet disc (13). The first permanent magnet disc (11) and the second permanent magnet disc (13) are respectively arranged on both sides of the flywheel (12). The N-stage and S-stage of the first permanent magnet disc (11) and the second permanent magnet disc (13) are oriented in the same direction.

7. The tuned mass damper based on nitrogen spring-convex mechanism according to claim 1, characterized in that: The permanent magnet disc comprises permanent magnet disc teeth (111) and non-conductor disc teeth (112) that are arranged at intervals.

8. A seismic isolation method based on a nitrogen spring-convex mechanism, characterized in that: The method uses the tuned mass damper according to any one of claims 1 to 7 to perform seismic isolation of a main structure, and the method comprises the following steps: The convex spring structure (2) has two processes. The first process is: in the initial stage, the preload provided by the multi-stage nitrogen spring next to the center rod (22) is large, and the friction convex surface next to the center rod (22) moves together with the center rod (22) under the action of the preload of the multi-stage nitrogen spring next to it, without generating relative displacement; the second process is: as the vertical relative displacement of the convex spring structure (2) and the nitrogen spring structure (3) increases, the preload provided by the multi-stage nitrogen spring next to it decreases, and the friction convex surface next to it and the center rod (22) move relative to each other, and the contact surface generates Coulomb friction and performs damping energy consumption; The movement of the nitrogen spring structure (3) has two stages. The first stage: the cylinder and piston rod of the previous stage form the nitrogen spring of the previous stage, and the cross-sectional area of ​​the piston rod is smaller than the cross-sectional area of ​​the piston, thereby generating a pressure difference, providing pre-stress for the convex spring structure (2); the second stage: as the piston rod of the previous stage moves to the end point, the inner cavity of the piston rod of the previous stage serves as the cylinder of the next stage, and nitrogen enters the cylinder of the next stage through the hole. The cylinder and piston rod of the next stage form the nitrogen spring of the next stage, and similarly, the cross-sectional area of ​​the piston rod is smaller than the cross-sectional area of ​​the piston, providing pre-stress for the convex spring structure (2). The difference between the cross-sectional area of ​​the piston rod of the next stage and the piston is different from the difference between the cross-sectional area of ​​the piston rod of the previous stage and the piston, providing different pre-stress effects for the convex spring structure (2); The center rod (22) and the multi-stage nitrogen spring and friction convex surface next to it are connected to the ball screw flywheel structure (1) through the first spring (21). The ball screw flywheel structure (1) converts the vertical displacement of the threaded screw (15) into the rotation of the ball nut (14), thereby driving the flywheel (12) to rotate, generating an inertia effect. The conductive flywheel gear (121) and the non-conductive flywheel gear (122) of the flywheel (12) rotate to cut the magnetic flux lines generated by the first permanent magnet disc (11) and the second permanent magnet disc (13), forming an eddy current effect to damp energy consumption; The ball screw flywheel structure (1) is connected to the main structure (5) through the convex spring structure (2) and the nitrogen spring structure (3). When the main structure (5) vibrates, that is, when a vertical displacement is generated, a relative displacement occurs between the ball screw flywheel structure (1) and the main structure (5). The spring provides linear positive stiffness, and the nitrogen spring-convex mechanism composite negative stiffness unit composed of the convex structure of the nitrogen spring and the friction convex surface provides multi-level nonlinear negative stiffness related to the displacement, thereby realizing flexible adjustment of the stiffness and further realizing flexible adjustment of the vibration isolation frequency domain.

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