Passive quasi-zero stiffness vibration isolation unit for floating slab track and track system

Abstract

The application provides a passive quasi-zero stiffness vibration isolation unit and track system for a floating slab track, wherein the vibration isolation unit comprises a shell with a support disc, and an internal positive stiffness mechanism, a negative stiffness mechanism and a mechanical coupling structure; the positive stiffness mechanism comprises a mechanical spring and a positive stiffness gas spring arranged in parallel, the mechanical spring provides a main static load path independent of gas pressure and generates a restoring force that increases with displacement when compressed; the negative stiffness mechanism comprises a plurality of negative stiffness gas springs uniformly distributed around the positive stiffness mechanism; the mechanical coupling structure is used to connect the positive stiffness mechanism and the negative stiffness mechanism, and the negative stiffness gas springs are stretched under the driving of the mechanical coupling structure to generate a restoring force that decreases with displacement; the two compensate for each other within a predetermined working displacement, so that the vibration isolation unit presents a quasi-zero stiffness characteristic near the equilibrium position. The application has a simple, stable and reliable structure, is a passive design, can maintain high static load capacity, and effectively attenuates low-frequency and ultra-low-frequency vibrations.

Description

Technical Field

[0001] This invention relates to the field of track vibration reduction technology, and in particular to a passive quasi-zero stiffness vibration isolation unit and track system for floating slab tracks. Background Technology

[0002] Floating slab track systems are widely used in urban rail transit and high-speed railways, primarily to isolate the vibrations and noise generated by vehicle operation from propagating to surrounding structures. Existing floating slab tracks mostly employ linear elastic pads, steel springs, or pneumatic components as vibration isolation devices. These devices present an inherent contradiction between static load-bearing capacity and low-frequency vibration isolation performance: to achieve good low-frequency or ultra-low-frequency vibration isolation, the isolators need to have low stiffness; however, excessively low stiffness will weaken the system's static stability and load-bearing capacity, making it difficult to meet the requirements of heavy-haul railways.

[0003] Quasi-zero stiffness (QZS) vibration isolation technology, through the rational configuration of positive and negative stiffness elements, can significantly reduce the effective stiffness near the equilibrium point, thus theoretically balancing low-frequency vibration isolation and load-bearing capacity. However, existing QZS mechanisms often rely on friction-sensitive linkages, buckling members, cam geometry, magnetic forces, or active control systems to achieve negative stiffness characteristics. Such solutions generally suffer from insufficient reliability, complex structures, and high maintenance costs, and are particularly unsuitable for ballastless track systems operating in harsh environments for extended periods.

[0004] Therefore, there is an urgent need to develop a passive quasi-zero stiffness vibration isolation unit and track system for floating slab tracks that is simple in structure, stable and reliable, and operates passively, so that it can effectively attenuate low-frequency and ultra-low-frequency vibrations while maintaining high static load capacity. Summary of the Invention

[0005] The purpose of this invention is to provide a passive quasi-zero stiffness vibration isolation unit and track system for floating slab tracks, aiming to solve the technical problems of existing floating slab tracks having difficulty in balancing low-frequency vibration isolation and load-bearing capacity, and the complex and unreliable passive QZS structure.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a passive quasi-zero stiffness vibration isolation unit for floating slab tracks, comprising:

[0007] The housing includes a housing body with an opening at the top and a support plate disposed at the opening of the housing body;

[0008] A positive stiffness mechanism is disposed within the outer shell body, and includes a mechanical spring and a positive stiffness gas spring arranged in parallel;

[0009] A negative stiffness mechanism is disposed within the outer shell body, and includes a plurality of negative stiffness gas springs evenly distributed around the positive stiffness mechanism;

[0010] A mechanical coupling structure is used to connect the positive stiffness mechanism and the negative stiffness mechanism so that synchronous displacement occurs between the positive stiffness mechanism and the negative stiffness mechanism;

[0011] The mechanical spring is used to establish a main static load path independent of air pressure. When the vibration isolation unit is compressed, the positive stiffness mechanism is compressed and generates a restoring force that increases with displacement. The negative stiffness mechanism extends under the drive of the mechanical coupling structure and generates a restoring force that decreases with displacement, so that the two compensate each other within a predetermined working displacement range, so that the vibration isolation unit exhibits quasi-zero stiffness characteristics near the working equilibrium position.

[0012] As a further improvement to the above solution, the mechanical spring is a mechanical helical spring, which is used to continue to bear the load when the positive stiffness gas spring or the negative stiffness gas spring experiences air pressure loss, so as to form a fault-safe mechanical load-bearing path.

[0013] As a further improvement to the above solution, the bottom of the outer shell body is provided with a bottom cover, the remote extension end of the positive stiffness gas spring is located inside the bottom cover, and its extension end is connected to a top cover.

[0014] The mechanical spring is sleeved outside the positive stiffness gas spring, with one end abutting against the lower surface of the top cover and the other end abutting against the upper surface of the bottom cover.

[0015] The support plate has a through hole in the middle, and the top cover passes through the through hole and extends out of the support plate, forming a load-bearing platform for the vibration isolation unit.

[0016] As a further improvement to the above solution, the positive stiffness gas spring includes a cylinder and a piston rod slidably disposed in the cylinder; the rod end of the piston rod is connected to the top cover, and the cylinder is disposed in the bottom cover;

[0017] The negative stiffness gas spring and the positive stiffness gas spring use the same gas spring structure. The difference between the two is that the piston rod length of the negative stiffness gas spring is different.

[0018] The negative stiffness gas spring has its extension end located on the inner surface of the support plate, and its extension end is connected to the mechanical coupling structure.

[0019] Preferably, the negative stiffness mechanism includes four negative stiffness gas springs, which are evenly distributed around the positive stiffness mechanism.

[0020] As a further improvement to the above solution, the mechanical coupling structure includes multiple L-shaped connecting rods, one end of each L-shaped connecting rod being connected to the load-bearing platform of the positive stiffness mechanism, i.e., connected to the top cover; the other end being connected to the telescopic end of the corresponding negative stiffness gas spring.

[0021] Preferably, the vertical section of the L-shaped connecting rod is connected to the lower surface of the top cover, and the horizontal section of the L-shaped connecting rod is connected to the telescopic end of the negative stiffness gas spring.

[0022] As a further improvement to the above solution, a plurality of vertical support rods are provided between the support plate and the bottom of the outer shell body, and the vertical support rods are used to provide additional vertical support for the support plate.

[0023] In a second aspect, the present invention also provides a passive quasi-zero stiffness floating slab track system, including rails, ballastless concrete floating slabs, a substructure, and multiple vibration isolation units as described in the first aspect.

[0024] The steel rail is set on top of the ballastless concrete floating slab, and the ballastless concrete floating slab is set on the lower foundation.

[0025] Multiple vibration isolation units are disposed between the ballastless concrete floating slab and the lower foundation, and are arranged at intervals along the length of the ballastless concrete floating slab to support static track loads and dynamic train excitation.

[0026] The track system is a passive structure without sensors, actuators, or active control units.

[0027] As a further improvement to the above solution, the lower foundation is a concrete base set on the main beam or supporting structure of the bridge, and multiple vibration isolation units are embedded in the concrete base.

[0028] Specifically, multiple vibration isolation units are installed in the concrete base through detachable clamps and positioned and fixed by locking plates.

[0029] As a further improvement to the above solution, a buffer is also provided between the outer shell of the vibration isolation unit and the concrete base.

[0030] As a further improvement to the above solution, the ballastless concrete floating slab is connected to the vibration isolation unit by a connecting plate. The four sides of the connecting plate are connected to the ballastless concrete floating slab, and the middle part of the connecting plate is connected to the load-bearing platform of the vibration isolation unit.

[0031] As a further improvement to the above scheme, during dynamic loading, when the positive stiffness gas spring of the vibration isolation unit is compressed, the negative stiffness gas spring of the vibration isolation unit expands; during unloading, the positive stiffness gas spring of the vibration isolation unit expands, and the negative stiffness gas spring of the vibration isolation unit is compressed.

[0032] Because the present invention adopts the above technical solutions, the beneficial effects of this application are as follows:

[0033] 1. This invention provides a passive quasi-zero stiffness vibration isolation unit for floating slab tracks. It employs a positive stiffness mechanism consisting of a mechanical spring and a positive stiffness gas spring connected in parallel, combined with a negative stiffness mechanism consisting of multiple sets of negative stiffness gas springs evenly distributed around the positive stiffness mechanism. A mechanical coupling structure is introduced between the two to achieve synchronous displacement, causing the vibration isolation unit to exhibit quasi-zero stiffness characteristics near its working equilibrium position. This invention achieves the following beneficial effects:

[0034] This invention balances low-frequency vibration isolation with load-bearing capacity. Specifically, the mechanical spring establishes the main static load path independently of air pressure, ensuring the system's stability and load-bearing capacity under heavy static loads. Simultaneously, as the positive stiffness mechanism generates a restoring force that increases with displacement under compression, the negative stiffness mechanism extends under coupling and generates a restoring force that decreases with increasing displacement. The stiffnesses of these two mechanisms cancel each other out within a specific displacement range, thereby reducing the overall effective stiffness. This design achieves excellent vibration isolation performance in the low-frequency and even ultra-low-frequency ranges without sacrificing load-bearing capacity.

[0035] The present invention has a simple structure and high reliability. Specifically, compared with the prior art that relies on friction-sensitive linkage mechanisms, buckling members or active control systems, the negative stiffness characteristics of the present invention are achieved entirely by a passive gas spring in conjunction with a mechanical coupling structure, which avoids complex kinematic pairs and electronic control components, reduces failure risk and maintenance costs, and is more suitable for ballastless track systems that have been in service for a long time in harsh environments.

[0036] This invention adopts a passive working mode, requiring no external energy input or real-time control. It can automatically adapt to the dynamic load changes generated by train operation by relying on the physical characteristics of mechanical springs and gas springs, thereby improving the system's durability and environmental adaptability.

[0037] Multiple vibration isolation units are spaced apart along the length of the floating slab, which can uniformly transmit and attenuate vibration energy, further improving the overall vibration control effect of the track structure. This invention, through the combination of positive and negative stiffness mechanisms and mechanical coupling design, can effectively solve the contradiction between low-frequency vibration isolation and load-bearing capacity in existing floating slab tracks. At the same time, it has the advantages of simple structure, reliable operation, and convenient maintenance, and can meet the needs of urban rail transit and high-speed railways for high-performance passive vibration isolation.

[0038] 2. The present invention provides a passive quasi-zero stiffness floating slab track system, which forms an integral support and vibration isolation system by arranging multiple quasi-zero stiffness vibration isolation units at a certain interval between the ballastless concrete floating slab and the underlying foundation. Firstly, it enables continuous low-stiffness vibration isolation throughout the track system. Specifically, each vibration isolation unit exhibits quasi-zero stiffness characteristics near its equilibrium position. When a train load is applied, the system as a whole simultaneously reduces its effective stiffness at multiple support points, giving the floating slab significant overall vibration isolation capability in the low-frequency and ultra-low-frequency ranges, effectively reducing the propagation of vibration to surrounding structures and the ground.

[0039] Secondly, it ensures uniform static load distribution in the track system, improving structural stability. Specifically, since each vibration isolation unit is equipped with a mechanical spring as the main static load path independent of air pressure, and each unit is evenly distributed along the length of the floating slab, the static track load is borne by all vibration isolation units, avoiding local stress concentration and ensuring uniform deformation and structural stability of the floating slab under heavy load conditions.

[0040] Furthermore, this allows the track system to adapt to long spans and varying geological conditions. Specifically, the passive quasi-zero stiffness vibration isolation units have a consistent structure and standardized installation method. By adjusting the number of units and their spacing, they can flexibly adapt to track conditions with different spans and foundation stiffnesses, ensuring the system maintains good vibration isolation and load-bearing performance in various engineering environments. Simultaneously, the track system adopts a fully passive operating mode, with no easily damaged electronic or mechanical control components. The vibration isolation units contain only mechanical and gas springs, whose fatigue resistance and anti-aging properties are suitable for long-term service in high-humidity, high-temperature, and frequent-vibration rail transit environments, reducing the total life-cycle maintenance cost.

[0041] In addition, in the vibration transmission path of the track system from rail to floating slab to vibration isolation unit to substructure, the quasi-zero stiffness vibration isolation unit provides high vibration isolation efficiency in the critical low and medium frequency range. Combined with the mass effect of the floating slab, it can significantly reduce the structural radiation noise when the train passes and improve the comfort of the environment along the line.

[0042] The passive quasi-zero stiffness floating slab track system provided by this invention combines structural layout with the characteristics of vibration isolation units to achieve effective control of low-frequency and ultra-low-frequency vibrations while ensuring high static load capacity. It also has advantages such as structural stability, strong environmental adaptability, and low operation and maintenance costs, and can fully meet the vibration reduction and noise reduction needs of modern urban rail transit and high-speed railways. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0044] Figure 1 This is a three-dimensional schematic diagram of a passive quasi-zero stiffness vibration isolation unit for a floating slab track disclosed in Embodiment 1 of the present invention;

[0045] Figure 2 This is a three-dimensional schematic diagram of a passive quasi-zero stiffness vibration isolation unit for a floating slab track disclosed in Embodiment 1 of the present invention, with the outer shell removed.

[0046] Figure 3 This is a three-dimensional schematic diagram of a passive quasi-zero stiffness vibration isolation unit for a floating slab track disclosed in Embodiment 1 of the present invention, with the support plate removed.

[0047] Figure 4 This is a three-dimensional schematic diagram of a passive quasi-zero stiffness vibration isolation unit for a floating slab track disclosed in Embodiment 1 of the present invention, with the outer shell removed.

[0048] Figure 5 This is a front view schematic diagram of the connection between the positive stiffness mechanism and the top cover and bottom cover disclosed in Embodiment 1 of the present invention;

[0049] Figure 6 This is a three-dimensional schematic diagram of the positive stiffness gas spring disclosed in Embodiment 1 of the present invention;

[0050] Figure 7 This is a BB cross-sectional schematic diagram of the positive stiffness gas spring disclosed in Embodiment 1 of the present invention;

[0051] Figure 8 This is a front view schematic diagram of the connection between a passive quasi-zero stiffness vibration isolation unit for a floating slab track and a connecting plate, as disclosed in Embodiment 1 of the present invention.

[0052] Figure 9 This is a three-dimensional schematic diagram of a passive quasi-zero stiffness floating slab track system disclosed in Embodiment 2 of the present invention;

[0053] Figure 10 This is a three-dimensional schematic diagram of multiple vibration isolation units arranged under a ballastless concrete floating slab, as disclosed in Embodiment 2 of the present invention. Figure 1 ;

[0054] Figure 11 This is a three-dimensional schematic diagram of multiple vibration isolation units arranged under a ballastless concrete floating slab, as disclosed in Embodiment 2 of the present invention. Figure 2 ;

[0055] Figure 12 This is a transverse sectional view of the multiple vibration isolation units disclosed in Embodiment 2 of the present invention, which are arranged under the ballastless concrete floating slab.

[0056] Figure 13 This is a three-dimensional schematic diagram of a concrete base with a clamp and a locking plate installed, as disclosed in Embodiment 2 of the present invention.

[0057] Figure label:

[0058] 01. Vibration isolation unit; 1. Housing; 11. Housing body; 12. Support plate; 13. Through hole; 2. Positive stiffness mechanism; 21. Mechanical spring; 22. Positive stiffness gas spring; 221. Cylinder; 222. Piston rod; 3. Negative stiffness mechanism; 31. Negative stiffness gas spring; 4. Mechanical coupling structure; 41. L-shaped connecting rod; 5. Bottom cover; 6. Top cover; 7. Vertical support rod;

[0059] 02. Rail; 03. Ballastless concrete floating slab; 04. Concrete base; 05. Bridge main beam or supporting structure; 06. Clamp; 07. Locking plate; 08. Connecting plate.

[0060] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0063] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0064] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0065] Example 1

[0066] See Figures 1-8 This invention provides a passive quasi-zero stiffness vibration isolation unit 01 for floating slab tracks. The vibration isolation unit 01 includes a shell 1, a positive stiffness mechanism 2, a negative stiffness mechanism 3, and a mechanical coupling structure 4. These components are arranged in a coordinated manner so that the vibration isolation unit 01 can achieve quasi-zero stiffness characteristics near its working equilibrium position while bearing the load transmitted by the floating slab track, thus simultaneously meeting both support and vibration isolation requirements.

[0067] Specifically, the outer shell 1 serves as the mounting and support component of the vibration isolation unit 01, accommodating and securing the internal mechanisms. The outer shell 1 includes a shell body 11 and a support plate 12. The shell body 11 is a hollow structure with an opening at the top, and the support plate 12 is positioned at the opening of the shell body 11 and connected to it. By providing the outer shell 1, relatively concentrated mounting space can be provided for the positive stiffness mechanism 2, the negative stiffness mechanism 3, and the mechanical coupling structure 4, making the internal structure of the vibration isolation unit 01 more compact. This also helps maintain the relative positional relationship between the mechanisms, thus providing a structural foundation for the stable operation of the vibration isolation unit 01. Furthermore, the shell body 11 can be made of a high-strength metal material to reduce the adverse effects of significant deformation of the shell 1 under load and vibration conditions on the installation state of the internal mechanisms, thereby improving the overall structural stability of the vibration isolation unit 01.

[0068] The positive stiffness mechanism 2 is disposed within the outer shell 11 and is used to provide positive stiffness restoring force. The positive stiffness mechanism 2 includes a mechanical spring 21 and a positive stiffness gas spring 22, which are connected in parallel. This arrangement allows the mechanical spring 21 and the positive stiffness gas spring 22 to jointly participate in the load-bearing and restoring process of the vibration isolation unit 01. The mechanical spring 21 establishes a main static load path independent of air pressure, enabling the vibration isolation unit 01 to obtain relatively stable mechanical support under normal operating conditions. Compared to a structure relying solely on a gas spring for load bearing, this helps reduce the impact of air pressure fluctuations on load-bearing stability. The positive stiffness gas spring 22 provides a restoring force that increases with displacement during the loaded displacement process and can cooperate with the mechanical spring 21 to share the load. By connecting the two in parallel, the static load support requirements of the vibration isolation unit 01 are met, and a basis is provided for subsequent restoring force compensation with the negative stiffness mechanism 3, thus balancing load-bearing capacity and vibration isolation performance.

[0069] The negative stiffness mechanism 3 is also disposed within the outer shell 11, providing negative stiffness restoring force and cooperating with the positive stiffness mechanism 2 to form a quasi-zero stiffness characteristic. The negative stiffness mechanism 3 includes multiple negative stiffness gas springs 31, which are uniformly arranged around the positive stiffness mechanism 2. By arranging multiple negative stiffness gas springs 31 around the positive stiffness mechanism 2, the negative stiffness mechanism 3 and the positive stiffness mechanism 2 can form a relatively compact spatial relationship, and the negative stiffness effect is more evenly distributed around the positive stiffness mechanism 2. This arrangement reduces the adverse effects of uneven local force on the stability of the vibration isolation unit 01, and also facilitates the arrangement of the negative stiffness mechanism 3 within a limited installation space. Furthermore, the negative stiffness gas springs 31 can generate a restoring force that decreases with increasing displacement during operation, thereby compensating for the restoring force of the positive stiffness mechanism 2, and thus providing conditions for the vibration isolation unit 01 to form a quasi-zero stiffness characteristic near its working equilibrium position.

[0070] The mechanical coupling structure 4 connects the positive stiffness mechanism 2 and the negative stiffness mechanism 3, enabling them to move synchronously. By setting the mechanical coupling structure 4, the displacement of the loaded platform after being subjected to force can be transmitted from the positive stiffness mechanism 2 to the negative stiffness mechanism 3, creating a clear linkage between them during loading and rebound. This improves the consistency of their actions, reduces the impact of asynchronous displacement on the restoring force compensation relationship, and thus helps maintain the stability of the vibration isolation unit 01 during operation. Furthermore, the mechanical coupling structure 4 can adopt a rigid connection form to directly transmit displacement and force, thereby meeting the needs of internal linkage and coordination within the vibration isolation unit 01.

[0071] In this embodiment, the vibration isolation unit 01 operates as follows: When the floating plate track transmits the load to the vibration isolation unit 01, the load-bearing platform located on top of the positive stiffness mechanism 2 transmits the load to the positive stiffness mechanism 2, and the mechanical coupling structure 4 simultaneously drives the negative stiffness mechanism 3 to move synchronously. At this time, the positive stiffness mechanism 2 is compressed, and the mechanical spring 21 and the positive stiffness gas spring 22 together generate a restoring force that increases with displacement to support the upper load; at the same time, the negative stiffness mechanism 3 undergoes corresponding displacement under the drive of the mechanical coupling structure 4, and each negative stiffness gas spring 31 generates a restoring force that decreases with increasing displacement. In this way, the positive stiffness mechanism 2 and the negative stiffness mechanism 3 can form a restoring force compensation relationship within a predetermined working displacement range, so that the vibration isolation unit 01 exhibits quasi-zero stiffness characteristics near the working equilibrium position. Through the above structure and working method, the vibration isolation unit 01 can improve the transmission of low-frequency vibrations while ensuring basic load-bearing functions. At the same time, since the mechanical spring 21 establishes a main static load path independent of the air pressure state, it is beneficial to improve the support stability of the vibration isolation unit 01 during long-term operation.

[0072] In some embodiments, the number of negative stiffness gas springs 31 can be selected according to the design load, installation space, and target working displacement range, preferably multiple, to take into account both the distribution of negative stiffness and structural layout requirements. The structural parameters of the mechanical spring 21 and the positive stiffness gas spring 22 can also be matched and designed according to the load magnitude and target displacement range of the floating plate track system, so that the positive stiffness mechanism 2 and the negative stiffness mechanism 3 form a more suitable restoring force compensation relationship within the predetermined working range. Through the above parameter matching, the adaptability between the vibration isolation unit 01 and the actual working conditions can be further improved.

[0073] The negative stiffness characteristic of this invention is achieved entirely by a passive gas spring in conjunction with a mechanical coupling structure 4. Compared to existing technologies that rely on friction-sensitive linkage mechanisms, buckling members, or active control systems, this avoids complex kinematic pairs and electrical control components, reducing failure risks and maintenance costs. It is more suitable for ballastless track systems that operate in harsh environments for extended periods. Furthermore, this invention adopts a passive operating mode, requiring no external energy input or real-time control. It automatically adapts to dynamic load changes generated by train operation based on the physical characteristics of the mechanical spring 21 and the gas spring, improving the system's durability and environmental adaptability.

[0074] Multiple vibration isolation units 01 are spaced apart along the length of the floating slab, which can uniformly transmit and attenuate vibration energy, further improving the overall vibration control effect of the track structure. This invention, through the combination and mechanical coupling design of the positive stiffness mechanism 2 and the negative stiffness mechanism 3, can effectively solve the contradiction between low-frequency vibration isolation and load-bearing capacity in existing floating slab tracks. It also has the advantages of simple structure, reliable operation, and convenient maintenance, and can meet the needs of urban rail transit and high-speed railways for high-performance passive vibration isolation.

[0075] In a preferred embodiment, the mechanical spring 21 is a mechanical helical spring, which, together with the positive stiffness gas spring 22, participates in the load-bearing of the vibration isolation unit 01. By setting the mechanical spring 21 as a mechanical helical spring, on the one hand, its elastic support capacity can be used to provide a stable foundation load for the vibration isolation unit 01; on the other hand, it is convenient to form a cooperative force-bearing relationship with the positive stiffness gas spring 22, so that the vibration isolation unit 01 can meet the static load support requirements while providing a basis for the restoring force compensation between the subsequent positive stiffness mechanism 2 and negative stiffness mechanism 3.

[0076] Specifically, when the vibration isolation unit 01 is in normal working condition, the load from the floating plate and the upper track structure is transferred to the positive stiffness mechanism 2, where the mechanical helical spring and the positive stiffness gas spring 22 jointly bear the load. The positive stiffness gas spring 22 provides a restoring force that increases with displacement during compression, while the mechanical helical spring provides mechanical support independent of air pressure. Since the mechanical helical spring is an independent mechanical load-bearing element and does not rely on gas pressure to maintain its support capacity, it can continuously provide stable support during the operation of the vibration isolation unit 01. This configuration means that the vibration isolation unit 01 does not rely entirely on pneumatic components for load bearing, which helps improve the clarity of the overall load-bearing path and operational stability, thereby mitigating the problem that the support capacity is easily affected under abnormal operating conditions when only gas springs are used for load bearing.

[0077] Furthermore, when the positive stiffness gas spring 22 or the negative stiffness gas spring 31 experiences air pressure loss, the mechanical helical spring continues to bear the load, ensuring that the vibration isolation unit 01 maintains its basic support function, thus forming a fail-safe mechanical load-bearing path. That is, when the gas spring experiences pressure loss, air leakage, or a decrease in load-bearing capacity, the mechanical helical spring can still provide necessary support to the floating slab and its upper structure, preventing the vibration isolation unit 01 from suddenly losing its support function or becoming structurally unstable due to a decrease in its pneumatic support capacity. Through the above settings, this embodiment, while considering the quasi-zero stiffness vibration isolation requirements, improves the safety margin of the vibration isolation unit 01 under abnormal operating conditions, making it more suitable for floating slab track scenarios with high requirements for operational continuity and structural safety.

[0078] In a preferred embodiment, the bottom of the outer shell 11 is provided with a bottom cover 5, and the positive stiffness gas spring 22 is disposed inside the outer shell 11, with the end of the positive stiffness gas spring 22 away from the extension end disposed inside the bottom cover 5, and its extension end connected to a top cover 6. By installing the bottom end of the positive stiffness gas spring 22 at the bottom cover 5 and arranging its extension end toward the support plate 12, the positive stiffness gas spring 22 can form a relatively clear vertical force line inside the vibration isolation unit 01, which facilitates the downward transmission of the upper load along the positive stiffness mechanism 2 to the outer shell 11 and the foundation structure. It also provides an installation basis for the coaxial arrangement of the mechanical spring 21, thereby contributing to the compact design of the overall structure of the vibration isolation unit 01.

[0079] Furthermore, the mechanical spring 21 is sleeved outside the positive stiffness gas spring 22, with one end of the mechanical spring 21 abutting against the lower surface of the top cover 6 and the other end abutting against the upper surface of the bottom cover 5. That is, the mechanical spring 21 and the positive stiffness gas spring 22 are arranged along the same axis, and structurally they form an inner and outer sleeve relationship. This arrangement reduces the space occupied by the vibration isolation unit 01 in the lateral direction, making the positive stiffness mechanism 2 more compact and easier to install in the limited space of the floating plate track system. On the other hand, by abutting against the top cover 6 and the bottom cover 5 respectively, the mechanical spring 21 can be compressed or rebounded synchronously when the top cover 6 moves up and down with the load, thus sharing the vertical load with the positive stiffness gas spring 22. With this arrangement, the mechanical spring 21 participates in the load-bearing under normal working conditions and can continue to provide mechanical support in abnormal situations such as the gas spring losing pressure. Therefore, it helps to form a load-bearing path independent of the air pressure state and improves the support reliability of the vibration isolation unit 01 under abnormal working conditions.

[0080] In this embodiment, the support plate 12 has a through hole 13 in the middle, and the top cover 6 passes through the through hole 13 and extends out of the support plate 12, forming the load-bearing platform of the vibration isolation unit 01. Thus, the top cover 6 not only serves as a connecting component for the extension end of the positive stiffness gas spring 22, but also directly as the force-bearing part for the upper load input to the vibration isolation unit 01. With this arrangement, the floating plate or the connecting plate 08 connected to the floating plate can directly cooperate with the load-bearing platform, directly transmitting the external load to the positive stiffness mechanism 2, reducing intermediate force transmission links, thereby simplifying the force path and improving the directness of structural force transmission. Simultaneously, since the top cover 6 extends through the through hole 13 of the support plate 12, the top cover 6 can form a clear motion relationship with the support plate 12 during vertical displacement. This also provides structural conditions for the mechanical coupling structure 4 to connect with the top cover 6 or the load-bearing platform, facilitating the synchronous transmission of the displacement of the positive stiffness mechanism 2 to the negative stiffness mechanism 3 during loading, thereby realizing the cooperative operation between the positive stiffness mechanism 2 and the negative stiffness mechanism 3.

[0081] Specifically, when the load of the floating plate and the upper track structure acts on the load-bearing platform, the top cover 6 drives the telescopic end of the positive stiffness gas spring 22 to move downward, and the positive stiffness gas spring 22 generates a restoring force that increases with displacement under pressure. At the same time, the mechanical spring 21, which is sleeved outside the positive stiffness gas spring 22, is compressed between the top cover 6 and the bottom cover 5, and provides stable mechanical support force. Since the top cover 6 extends directly out of the support plate 12 to form the load-bearing platform, the upper load can directly act on the positive stiffness mechanism 2, making the load-bearing path of the vibration isolation unit 01 clearer. Meanwhile, the displacement of the positive stiffness mechanism 2 can also be transmitted to the negative stiffness mechanism 3 through the mechanical coupling structure 4, so that the negative stiffness mechanism 3 participates in the restoring force compensation. Through the above arrangement, the core components of the positive stiffness mechanism 2 are coaxially integrated inside the outer shell 11, which not only helps to reduce the structural volume, but also facilitates the consistency of the force and movement direction, thereby improving the stability of the vibration isolation unit 01.

[0082] In some embodiments, the size of the through hole 13 is adapted to the shape of the top cover 6 to ensure that the top cover 6 can move vertically relative to the support plate 12; the inner diameter of the mechanical spring 21 is larger than the outer diameter of the positive stiffness gas spring 22 so that the mechanical spring 21 can be stably sleeved on the outside of the positive stiffness gas spring 22. Through the above structural fit, the ease of assembly of the positive stiffness mechanism 2 and its stability during movement can be further improved.

[0083] In this embodiment, the positive stiffness gas spring 22 includes a cylinder 221 and a piston rod 222 slidably disposed within the cylinder 221. The rod end of the piston rod 222 is connected to the top cover 6, and the cylinder 221 is disposed within the bottom cover 5. That is, the positive stiffness gas spring 22 is arranged vertically along the vibration isolation unit 01, with the cylinder 221 located at the lower part and the piston rod 222 extending upward and connected to the top cover 6. When the vibration isolation unit 01 is loaded, the top cover 6 drives the piston rod 222 to move relative to the cylinder 221 under the action of external load, thereby causing the positive stiffness gas spring 22 to generate corresponding gas compression and restoring forces. With this arrangement, the installation position of the positive stiffness gas spring 22 is clear, and the direction of force is consistent with the main bearing direction of the vibration isolation unit 01, which is conducive to forming a clear vertical force transmission path and facilitates coaxial arrangement with the mechanical spring 21 sleeved on the outside, thereby improving the overall compactness and stress stability of the positive stiffness mechanism 2.

[0084] Furthermore, the negative stiffness gas spring 31 and the positive stiffness gas spring 22 adopt the same gas spring structure, the difference being the length of the piston rod 222 of the negative stiffness gas spring 31. By using the same structure for the positive stiffness gas spring 22 and the negative stiffness gas spring 31, the selection, manufacturing, and assembly process of the gas spring components can be simplified while ensuring consistent working principles, facilitating the unified arrangement and maintenance of various pneumatic components within the vibration isolation unit 01. This arrangement eliminates the need to introduce entirely different types of actuators, helping to achieve the coordinated operation of the positive stiffness mechanism 2 and the negative stiffness mechanism 3 while maintaining a relatively simple structure.

[0085] In a preferred embodiment, the end of the negative stiffness gas spring 31 furthest from its extension end is located on the inner surface of the support plate 12, and its extension end is connected to the mechanical coupling structure 4. That is, the fixed end of the negative stiffness gas spring 31 is located on one side of the support plate 12, and its movable end establishes a kinematic connection with the positive stiffness mechanism 2 through the mechanical coupling structure 4. When the loaded platform moves downwards under external load, driving the positive stiffness mechanism 2, the mechanical coupling structure 4 simultaneously drives the extension end of the negative stiffness gas spring 31, allowing the negative stiffness gas spring 31 to participate in the restoring force adjustment process of the entire vibration isolation unit 01. By fixing the negative stiffness gas spring 31 to the inner surface of the support plate 12, its installation reference is clearly defined, and it is convenient to arrange it circumferentially around the positive stiffness mechanism 2, thereby shortening the force transmission chain, reducing intermediate connection levels, and improving the directness of the response and the stability of the arrangement of the negative stiffness mechanism 3.

[0086] Preferably, the negative stiffness mechanism 3 includes four negative stiffness gas springs 31, which are evenly distributed circumferentially around the positive stiffness mechanism 2. Using four negative stiffness gas springs 31 in a circumferentially distributed manner allows the negative stiffness mechanism 3 to form a more balanced spatial distribution around the positive stiffness mechanism 2, making the circumferential forces on the positive stiffness mechanism 2 more symmetrical during loading and displacement, which helps reduce the adverse effects of eccentric loading on the stability of the vibration isolation unit 01. Furthermore, the multiple negative stiffness gas springs 31 jointly participate in the negative stiffness response, facilitating a reasonable distribution of the negative stiffness effect within a limited installation space. Compared to unilateral or non-uniformly distributed arrangements, a circumferentially distributed structure is more conducive to maintaining the force coordination of the vibration isolation unit 01 during operation, thereby improving the overall operational stability.

[0087] In addition, the positive stiffness gas spring 22 is installed inside the bottom cover 5, and the negative stiffness gas spring 31 is installed on the inner surface of the support plate 12 and arranged around the positive stiffness mechanism 2. This makes the vibration isolation unit 01 form an overall structure with the positive stiffness mechanism 2 as the center and the negative stiffness mechanism 3 distributed around it in the circumferential direction. This helps to integrate the positive stiffness load, negative stiffness adjustment and mechanical coupling synchronization into the same vibration isolation unit 01. It achieves a more complete functional configuration without significantly increasing the lateral space occupied. Therefore, it is more suitable for use in floating slab track systems where the installation space is limited and the load-bearing stability is required.

[0088] In a preferred embodiment, the mechanical coupling structure 4 includes multiple L-shaped connecting rods 41. One end of each L-shaped connecting rod 41 is connected to the load-bearing platform of the positive stiffness mechanism 2, and the other end is connected to the telescopic end of the corresponding negative stiffness gas spring 31. The load-bearing platform is the top cover 6. By setting the mechanical coupling structure 4, the displacement of the positive stiffness mechanism 2 during the loading process can be synchronously transmitted to the negative stiffness mechanism 3, establishing a clear mechanical linkage between the positive stiffness mechanism 2 and the negative stiffness mechanism 3. This reduces the number of force transmission links and allows the load displacement of the positive stiffness mechanism 2 to act more directly on the negative stiffness gas spring 31, thereby helping to ensure the synergy between the two during operation and providing a structural basis for the coordinated changes of positive and negative stiffness restoring forces in the vibration isolation unit 01 near the working equilibrium position.

[0089] Specifically, when the upper load acts on the loaded platform, the top cover 6 moves vertically accordingly. The end of the L-shaped connecting rod 41 connected to the top cover 6 moves synchronously, and this displacement is transmitted to the extension end of the corresponding negative stiffness gas spring 31 via the L-shaped connecting rod 41. This causes the negative stiffness gas spring 31 to move synchronously with the positive stiffness mechanism 2. With this configuration, the positive stiffness mechanism 2 and the negative stiffness mechanism 3 no longer respond independently to external loads, but instead form a synchronous displacement relationship through the L-shaped connecting rod 41. This helps improve the timeliness and consistency of the negative stiffness mechanism 3's participation in restoring force adjustment, avoiding the problem of asynchronous movement between the two affecting the overall working stability of the vibration isolation unit 01.

[0090] Preferably, the vertical section of the L-shaped connecting rod 41 is connected to the lower surface of the top cover 6, and the horizontal section of the L-shaped connecting rod 41 is connected to the telescopic end of the negative stiffness gas spring 31. With this connection method, the vertical section can better adapt to the vertical movement direction of the top cover 6, allowing the vertical displacement of the load-bearing platform to be directly transmitted to the L-shaped connecting rod 41 along the vertical direction; the horizontal section is convenient to connect with the circumferentially arranged negative stiffness gas springs 31, thereby achieving a structural transition between the vertical load-bearing platform and the circumferential negative stiffness mechanism 3 within a limited space. This arrangement, on the one hand, helps to match the spatial arrangement of the mechanical coupling structure 4 with the positive stiffness mechanism 2 and the negative stiffness mechanism 3, avoiding an overly complex connection structure; on the other hand, it also helps to maintain a relatively consistent connection relationship between each negative stiffness gas spring 31 and the load-bearing platform, thereby improving the overall force and movement coordination of the vibration isolation unit 01.

[0091] Furthermore, since multiple L-shaped connecting rods 41 are connected one-to-one with multiple negative stiffness gas springs 31, when the top cover 6 moves under load, each negative stiffness gas spring 31 can respond synchronously under the action of the mechanical coupling structure 4. After the top cover 6 receives the upper load as a load-bearing platform, its displacement is directly transmitted to the negative stiffness gas springs 31 via the L-shaped connecting rods 41, without the need for additional complex conversion mechanisms. This simplifies the internal structure of the vibration isolation unit 01 and facilitates the linkage between the positive stiffness mechanism 2 and the negative stiffness mechanism 3 within a relatively compact installation space. Therefore, it is more suitable for applications in floating slab track systems where both structural compactness and operational reliability are required.

[0092] In a preferred embodiment, a plurality of vertical support rods 7 are provided between the support plate 12 and the bottom of the outer shell 11. These vertical support rods 7 are spaced apart circumferentially along the support plate 12 and connected between the support plate 12 and the bottom of the outer shell 11, providing additional vertical support for the support plate 12. Specifically, in this embodiment, four vertical support rods 7 are provided, and these four vertical support rods 7 are staggered with four negative stiffness gas springs 31 around the positive stiffness mechanism 2. By providing the vertical support rods 7 between the support plate 12 and the bottom of the outer shell 11, an auxiliary load-bearing path supporting the support plate 12 from the bottom upwards can be formed inside the outer shell 11. This allows the support plate 12 to obtain additional vertical support in addition to its own structure when subjected to forces from the upper mechanism and the negative stiffness mechanism 3.

[0093] Example 2

[0094] See Figures 9-13The present invention also provides a passive quasi-zero stiffness floating slab track system, including a steel rail 02, a ballastless concrete floating slab 03, a lower foundation, and a plurality of vibration isolation units 01 as described in Embodiment 1. The steel rail 02 is disposed on top of the ballastless concrete floating slab 03, the ballastless concrete floating slab 03 is disposed on the lower foundation, and the plurality of vibration isolation units 01 are disposed between the ballastless concrete floating slab 03 and the lower foundation, and are arranged at intervals along the length direction of the ballastless concrete floating slab 03.

[0095] In this embodiment, the rail 02 bears the train's running load and transfers the load to the ballastless concrete floating slab 03. The ballastless concrete floating slab 03, as the upper load-bearing structure, collects the static track load and dynamic train excitation transferred from the rail 02 and further transfers this load to multiple vibration isolation units 01 located below it. The lower foundation provides installation support for the entire track system. By setting multiple vibration isolation units 01 between the ballastless concrete floating slab 03 and the lower foundation, an elastic support system with vibration isolation function can be formed between the upper track structure and the lower foundation, thereby enabling the track system to meet load-bearing requirements while possessing corresponding vibration isolation capabilities.

[0096] Furthermore, multiple vibration isolation units 01 are arranged at intervals along the length of the ballastless concrete floating slab 03, forming multi-point support for the ballastless concrete floating slab 03 along its length. This arrangement, on the one hand, disperses the load borne by the ballastless concrete floating slab 03 and the rails 02 to multiple vibration isolation units 01, avoiding excessive load concentration in local areas; on the other hand, each vibration isolation unit 01 can jointly participate in supporting and responding to static track loads and dynamic train excitations, thereby improving the overall stress balance and stability of the floating slab track system during operation. Especially when the train load moves along the track direction, the multiple spaced vibration isolation units 01 can sequentially or jointly bear the load of the corresponding section, providing more continuous support conditions for the superstructure.

[0097] Since the vibration isolation unit 01 adopts the passive quasi-zero stiffness vibration isolation unit 01 structure described in Embodiment 1, during the operation of the track system, each vibration isolation unit 01 can not only bear the static load transmitted by the upper track structure, but also form quasi-zero stiffness characteristics near the working equilibrium position through the cooperation of the positive stiffness mechanism 2 and the negative stiffness mechanism 3. Based on this structure, the track system can adjust the vibration transmission path through the vibration isolation unit 01 set between the floating slab and the lower foundation without changing the overall track layout, thus making it more suitable for track scenarios that require both low-frequency vibration isolation and structural load-bearing capacity. At the same time, since the vibration isolation function is mainly realized by the structure of each vibration isolation unit 01 itself, it is also convenient to concentrate the vibration isolation design on the support part, reducing additional modifications to the rail 02 and the main structure of the floating slab.

[0098] In this embodiment, the track system is a passive structure without sensors, actuators, or active control units. That is, the track system does not rely on external active detection, feedback adjustment, or power actuation devices to achieve vibration isolation; instead, it relies on the structural configuration and stress response of each vibration isolation unit 01 to achieve support and vibration isolation. This design simplifies the track system structure, avoids the detection, control, and actuation stages involved in active control systems, reduces the complexity of the system composition, and minimizes maintenance factors introduced by electronic control or active actuation components. For track engineering scenarios, this passive structure is easier to integrate with existing floating slab track systems and also helps improve the structural adaptability of the system during long-term operation.

[0099] Specifically, when the train's running load is transferred from the rail 02 to the ballastless concrete floating slab 03, the ballastless concrete floating slab 03 distributes the load to multiple vibration isolation units 01 below. When each vibration isolation unit 01 bears a load, its internal positive stiffness mechanism 2, negative stiffness mechanism 3, and mechanical coupling structure 4 work together, ensuring that the upper load is supported and adjusted by the elastic support and restoring force of the vibration isolation unit 01 during the transfer to the lower foundation. This arrangement allows the track system to maintain a stable connection between the rail 02, the floating slab, and the lower foundation, while simultaneously enabling multiple vibration isolation units 01 to form a passive vibration isolation support network, thus balancing the load-bearing and vibration isolation requirements of the track structure.

[0100] In a preferred embodiment, the lower foundation is a concrete base 04 mounted on the main beam or supporting structure 05 of the bridge, and multiple vibration isolation units 01 are embedded within the concrete base 04. That is, the concrete base 04 serves as the lower installation foundation for the floating slab track system, fixedly mounted on the main beam or other supporting structure of the bridge, to bear the load transmitted from the upper ballastless concrete floating slab 03 and the vibration isolation units 01; the multiple vibration isolation units 01 are arranged inside the concrete base 04 and cooperate with the upper ballastless concrete floating slab 03 to form an elastic support relationship. By embedding the vibration isolation units 01 within the concrete base 04, a relatively compact overall installation structure can be formed between the vibration isolation units 01 and the lower foundation. This reduces the exposed portion of the vibration isolation units 01, facilitating coordination with the overall structure of the floating slab track system; it also improves the spatial stability of the vibration isolation units 01 after installation, making them more suitable for applications in track engineering that require both installation reliability and structural compactness.

[0101] Furthermore, the multiple vibration isolation units 01 are respectively installed in the concrete base 04 via detachable clamps 06 and positioned and fixed by locking plates 07. Specifically, the concrete base 04 has reserved installation space adapted to the vibration isolation units 01. After the vibration isolation units 01 are installed in the corresponding positions via the detachable clamps 06, they are positioned and fixed by the locking plates 07. With the above structure, the clamps 06 can serve as installation transition components between the vibration isolation units 01 and the concrete base 04, giving the vibration isolation units 01 a clearer installation boundary and support position within the concrete base 04, thereby improving assembly convenience and positional consistency during installation.

[0102] Meanwhile, since the clamp 06 is a detachable structure, when the vibration isolation unit 01 needs inspection, replacement, or maintenance, the corresponding vibration isolation unit 01 can be removed from the base and reinstalled without significantly damaging the main structure of the concrete base 04. Compared to directly casting or permanently fixing the vibration isolation unit 01 into the concrete base 04, this arrangement reduces the difficulty of later maintenance and replacement, and improves the maintenance convenience of the track system during long-term service. The locking plate 07 is used to further position and fix the installed vibration isolation unit 01, so that the vibration isolation unit 01 is not prone to displacement at the installation position when bearing the load transmitted by the upper floating plate and the running vibration, thereby helping to maintain the relative position stability between the vibration isolation unit 01, the floating plate, and the concrete base 04, and thus improving the working reliability of the entire support structure.

[0103] In this embodiment, multiple vibration isolation units 01 are installed within the concrete base 04 in the manner described above, allowing each vibration isolation unit 01 to form a relatively independent and positionally defined support unit within the underlying foundation. This arrangement not only facilitates the spaced arrangement of multiple vibration isolation units 01 along the length of the floating slab but also allows for independent installation and maintenance of each vibration isolation unit 01 according to the layout requirements of different sections. For floating slab track systems, this installation method balances the integrity of the foundation structure with the flexibility of the vibration isolation unit 01 arrangement, making it more suitable for track support scenarios that require long-term exposure to the dynamic and static loads of trains.

[0104] In a preferred embodiment, a buffer element is further provided between the outer shell 1 of the vibration isolation unit 01 and the concrete base 04. The buffer element is disposed between the outer periphery and / or bottom of the outer shell 1 of the vibration isolation unit 01 and the concrete base 04, forming an elastic buffer connection between the outer shell 1 of the vibration isolation unit 01 and the concrete base 04 after the vibration isolation unit 01 is installed inside the concrete base 04. By providing the buffer element between them, overly rigid direct contact between the outer shell 1 of the vibration isolation unit 01 and the concrete base 04 can be avoided, thereby reducing the adverse effects of local rigid collisions or hard contact on the structural stress and vibration transmission. Providing a buffer element between the outer shell 1 and the concrete base 04 creates an elastic transition between them. This arrangement, on the one hand, helps to alleviate the contact stress at the installation location of the vibration isolation unit 01 and improve the stress state between the outer shell 1 and the base; on the other hand, it also helps to reduce the additional vibration transmission caused by direct hard contact between the outer shell 1 and the base, thus making the connection between the vibration isolation unit 01 and the lower foundation more stable. Furthermore, the buffer can be set on the outer circumferential side of the housing 1 of the vibration isolation unit 01, the bottom support part, or both, to adapt to the needs of different installation structures.

[0105] In a preferred embodiment, the ballastless concrete floating slab 03 and the vibration isolation unit 01 are connected by a connecting plate 08. The connecting plate 08 is connected to the ballastless concrete floating slab 03 on all four sides, and to the load-bearing platform of the vibration isolation unit 01 in the middle. By setting the connecting plate 08 between the ballastless concrete floating slab 03 and the vibration isolation unit 01, a clear load transfer interface is formed between the upper floating slab structure and the lower vibration isolation unit 01, allowing the track load borne by the floating slab to be transferred to the vibration isolation unit 01 via the connecting plate 08.

[0106] The load-bearing platform is the part of the vibration isolation unit 01 used to bear the upper load. After the middle part of the connecting plate 08 is connected to the load-bearing platform, the static track load and dynamic train excitation transmitted from the floating plate and rail 02 can be directly input into the vibration isolation unit 01. With this arrangement, the positive stiffness mechanism 2, negative stiffness mechanism 3 and mechanical coupling structure 4 inside the vibration isolation unit 01 can respond around the load input, thereby enabling the vibration isolation unit 01 to better perform its supporting and vibration isolation functions. At the same time, the connecting plate 08, as the connecting component between the floating plate and the load-bearing platform, can also improve the convenience of assembly and connection between the two to a certain extent, making it easier to install and match according to the relative position of the floating plate and the vibration isolation unit 01.

[0107] In a preferred embodiment, during dynamic loading of the vibration isolation unit 01, when the positive stiffness gas spring 22 undergoes gas compression, the negative stiffness gas spring 31 undergoes gas expansion; during unloading, the positive stiffness gas spring 22 undergoes gas expansion, and the negative stiffness gas spring 31 undergoes gas compression. That is, the positive stiffness gas spring 22 and the negative stiffness gas spring 31 exhibit opposite gas volume changes during the operation of the vibration isolation unit 01.

[0108] Specifically, when the dynamic load of the upper floating plate and track structure is transmitted to the vibration isolation unit 01, the loaded platform moves downward under the load, driving the positive stiffness mechanism 2 to move. At this time, the piston rod 222 of the positive stiffness gas spring 22 moves relative to the cylinder 221, compressing the gas inside and generating a restoring force that increases with displacement. Simultaneously, the mechanical coupling structure 4 synchronously transmits the displacement of the loaded platform to the negative stiffness mechanism 3, causing the extension end of the negative stiffness gas spring 31 to move in a manner corresponding to the positive stiffness gas spring 22, and the gas volume inside the negative stiffness gas spring 31 increases and expands. With this arrangement, the positive stiffness gas spring 22 and the negative stiffness gas spring 31 form opposite gas state changes during the loading stage, thereby enabling the positive stiffness mechanism 2 and the negative stiffness mechanism 3 to cooperate during the same displacement process, which is beneficial for achieving restoring force compensation near the working equilibrium position.

[0109] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A passive quasi-zero stiffness vibration isolation unit for floating slab tracks, characterized in that, include: The housing includes a housing body with an opening at the top, a support plate disposed at the opening of the housing body, and a bottom cover disposed at the bottom of the housing body; A positive stiffness mechanism is installed inside the outer shell, which includes a mechanical spring and a positive stiffness gas spring arranged in parallel. The negative stiffness mechanism is located inside the outer shell and includes multiple negative stiffness gas springs evenly distributed around the positive stiffness mechanism. The positive stiffness gas spring has its distal end located inside the bottom cover, and its telescopic end is connected to the top cover; the mechanical spring is sleeved outside the positive stiffness gas spring, with one end abutting against the lower surface of the top cover and the other end abutting against the upper surface of the bottom cover; the support plate has a through hole in the middle, and the top cover passes through the through hole and extends out of the support plate, forming the load-bearing platform of the vibration isolation unit; A mechanical coupling structure is used to connect the positive stiffness mechanism and the negative stiffness mechanism so that synchronous displacement occurs between the positive stiffness mechanism and the negative stiffness mechanism. The mechanical coupling structure includes multiple L-shaped connecting rods, one end of each L-shaped connecting rod is connected to the load-bearing platform of the positive stiffness mechanism, and the other end is connected to the extension end of the corresponding negative stiffness gas spring. The mechanical spring is used to establish a main static load path independent of air pressure. When the vibration isolation unit is compressed, the positive stiffness mechanism is compressed and generates a restoring force that increases with displacement. The negative stiffness mechanism extends under the drive of the mechanical coupling structure and generates a restoring force that decreases with displacement, so that the two compensate each other within a predetermined working displacement range, so that the vibration isolation unit exhibits quasi-zero stiffness characteristics near the working equilibrium position.

2. The vibration isolation unit according to claim 1, characterized in that, The mechanical spring is a mechanical helical spring, used to continue bearing the load when the positive stiffness gas spring or the negative stiffness gas spring experiences air pressure loss, so as to form a fault-safe mechanical load-bearing path.

3. The vibration isolation unit according to claim 1, characterized in that, The positive stiffness gas spring includes a cylinder and a piston rod slidably disposed in the cylinder; the rod end of the piston rod is connected to the top cover, and the cylinder is disposed in the bottom cover; The negative stiffness gas spring and the positive stiffness gas spring adopt the same gas spring structure; The negative stiffness gas spring has its extension end located on the inner surface of the support plate, and its extension end is connected to the mechanical coupling structure.

4. The vibration isolation unit according to claim 1, characterized in that, Multiple vertical support rods are provided between the support plate and the bottom of the outer shell body, and the vertical support rods are used to provide additional vertical support for the support plate.

5. A passive quasi-zero stiffness floating slab track system, characterized in that, It includes steel rails, ballastless concrete floating slabs, a substructure, and multiple vibration isolation units as described in any one of claims 1-4. The steel rail is set on top of the ballastless concrete floating slab, and the ballastless concrete floating slab is set on the lower foundation. Multiple vibration isolation units are disposed between the ballastless concrete floating slab and the lower foundation, and are spaced apart along the length of the ballastless concrete floating slab to support static track loads and dynamic train excitation.

6. The track system according to claim 5, characterized in that, The lower foundation is a concrete base set on the main beam or supporting structure of the bridge, and multiple vibration isolation units are embedded in the concrete base; Specifically, the multiple vibration isolation units are installed in the concrete base through detachable clamps and are positioned and fixed by locking plates.

7. The track system according to claim 5, characterized in that, The ballastless concrete floating slab is connected to the vibration isolation unit via a connecting plate. The connecting plate is connected to the ballastless concrete floating slab on all four sides, and the middle part of the connecting plate is connected to the load-bearing platform of the vibration isolation unit.

8. The track system according to claim 5, characterized in that, During dynamic loading, when the positive stiffness gas spring of the vibration isolation unit is compressed, the negative stiffness gas spring of the vibration isolation unit expands; during unloading, the positive stiffness gas spring of the vibration isolation unit expands, and the negative stiffness gas spring of the vibration isolation unit is compressed.

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