Stiffness-adjustable quasi-zero stiffness vibration isolator

Abstract

The invention provides a stiffness-adjustable quasi-zero stiffness vibration isolator, and belongs to the technical field of low-frequency vibration isolation. Through creative parallel connection of the rocker mechanism and the obliquely-arranged cylindrical spiral spring, when the bearing platform is loaded and sinks to a balance position, the cylindrical spiral spring is in a horizontal critical state, and the negative rigidity provided by the cylindrical spiral spring and the nonlinear positive rigidity generated by the rocker mechanism counteract each other; the dynamic stiffness of the system near a balance point is close to zero; therefore, the device can generate extremely high vibration isolation efficiency on low-frequency micro-amplitude vibration; and the structural rigidity can be simply and conveniently adjusted to meet different bearing requirements. The device comprises a supporting base, a bearing platform and a supporting assembly connected between the supporting base and the bearing platform. The supporting assembly comprises a positive stiffness mechanism and a negative stiffness mechanism. The positive stiffness mechanism is a rocker mechanism, and the negative stiffness mechanism is an obliquely arranged elastic element; the supporting assembly further comprises a supporting column vertically arranged on the supporting base. The elastic element is a cylindrical spiral spring.

Description

Technical Field

[0001] This invention relates to an adjustable stiffness quasi-zero stiffness vibration isolator, specifically belonging to the field of low-frequency vibration isolation technology. Background Technology

[0002] Vibration phenomena in daily life and engineering practice have both advantages and disadvantages. For example, low-frequency vibrations in vehicles can affect train operation safety and passenger comfort; machine tool vibrations can easily lead to tool breakage and chipping; and space telescopes can experience image distortion due to low-frequency vibrations. Quasi-zero stiffness vibration isolators exhibit unique advantages in addressing these low-frequency vibration problems. They possess the mechanical characteristics of high static stiffness and low dynamic stiffness, which can effectively achieve low-frequency vibration isolation. This characteristic is crucial for their engineering applications. According to classical linear vibration isolation theory, linear vibration isolators only become effective when the external excitation frequency is a certain multiple higher than the system's natural frequency. If they are to be applied in the low-frequency range, the system stiffness must be reduced or the system mass must be increased. However, reducing stiffness weakens the structural load-bearing capacity, while increasing mass brings unnecessary burden. At the same time, there is an inherent contradiction between the low-frequency vibration transmissibility and the high-frequency vibration attenuation rate in traditional vibration isolation systems. Quasi-zero stiffness vibration isolators fundamentally solve this contradiction. Based on nonlinear theory, the "high static, low dynamic" characteristics of quasi-zero stiffness vibration isolators mean that under static conditions, they can provide sufficient support force; and under low-frequency excitation, they can significantly reduce vibration transmission. Therefore, the development of quasi-zero stiffness vibration isolators is of great significance for solving low-frequency vibration isolation problems in engineering practice. Summary of the Invention

[0003] The purpose of this invention is to provide an adjustable stiffness quasi-zero stiffness vibration isolator, which provides a high-efficiency low-frequency vibration isolation solution that is compact in structure, flexible in stiffness adjustment, reliable in performance, and easy to implement.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: the invention includes a support base, a bearing platform, and a support component connecting the support base and the bearing platform; The support components include a positive stiffness mechanism and a negative stiffness mechanism, which are connected in parallel to provide support for the load-bearing platform. The positive stiffness mechanism is a rocker mechanism, and the negative stiffness mechanism is an inclined elastic element.

[0005] Furthermore, by connecting the positive stiffness mechanism and the negative stiffness mechanism in parallel, the gradually hardening characteristic of the positive stiffness and the gradually softening characteristic of the negative stiffness cancel each other out near the equilibrium position, thereby achieving an ideal state where the dynamic stiffness is close to zero.

[0006] The support assembly also includes a column vertically mounted on the support base, and a rocker mechanism rotatably connected to the column and hinged to the bearing platform; the elastic element is a cylindrical helical spring, one end of which is hinged to the column and the other end of which is hinged to the bearing platform. Furthermore, the support pillars provide a robust and well-defined mounting point for the rocker mechanism and the inclined spring, ensuring that vibration energy can be efficiently and controllably transferred and canceled between the positive and negative stiffness mechanisms, thus guaranteeing the quality of the quasi-zero stiffness effect.

[0007] Both the rocker mechanism and the tilted cylindrical helical spring are symmetrically arranged around the center of the support platform; Furthermore, the symmetrical layout avoids platform tilting or instability caused by off-center loading, ensuring the reliability of the vibration isolator under various load conditions.

[0008] It also includes a sleeve fitted over the cylindrical helical spring, wherein the inner diameter of the sleeve is larger than the outer diameter of the cylindrical helical spring; Furthermore, by using the sleeve as a guiding mechanism, the bending and lateral deformation of the spring during compression are effectively limited, ensuring that it always moves along the axis, thereby improving the stability and accuracy of the vibration isolator.

[0009] The support column is detachably and securely connected to the support base via angle brackets and bolts; Furthermore, by using bolted connections, the entire vibration isolator can be disassembled and transported, then reassembled on-site, reducing transportation difficulties and costs.

[0010] The projected area of ​​the support base is larger than the projected area of ​​the support platform; Furthermore, the larger base area provides more stable support, significantly improving the stability of the vibration isolator when subjected to horizontal disturbances or eccentric loads, preventing the entire device from overturning and ensuring safety.

[0011] The rocker mechanism achieves fixed-axis rotation by engaging a rotating shaft fixed to the support column via a keyway; Furthermore, the keyway and the rotating shaft are matched to ensure the accuracy of the rocker mechanism's rotation center.

[0012] The supporting base and load-bearing platform are rectangular, circular, or polygonal in shape. Furthermore, the open shape selection allows the vibration isolator to be optimized in shape according to actual conditions such as installation space and equipment interfaces.

[0013] The beneficial effects of this invention are: 1. By creatively connecting the rocker mechanism (positive stiffness component) and the inclined cylindrical helical spring (negative stiffness component) in parallel, the inherent contradiction of traditional vibration isolators in the low-frequency range is fundamentally solved. Specifically, when the load-bearing platform sinks to the equilibrium position under load, the cylindrical helical spring is in a horizontal critical state. The negative stiffness provided by the cylindrical helical spring cancels out the nonlinear positive stiffness generated by the rocker mechanism, making the dynamic stiffness of the system near the equilibrium point approach zero. This ensures that the device can generate extremely high vibration isolation efficiency for low-frequency micro-amplitude vibrations.

[0014] 2. Multiple profile supports are vertically fixed to the support base via angle brackets and bolts, providing a stable installation foundation and precise force transmission path for each moving part; at the same time, the sleeve fitted outside the spring effectively prevents the spring from buckling, ensuring the accuracy of its mechanical behavior and the reliability of long-term operation.

[0015] 3. By designing the support base with a projected area larger than the load-bearing platform, the overturning resistance of the entire system is significantly enhanced, ensuring the stability of the device. The positive and negative stiffness mechanisms are arranged symmetrically around the center of the load-bearing platform, ensuring uniform load distribution and isotropic vibration isolation performance. The detachable design with bolted connections between all components not only facilitates transportation and on-site installation and commissioning but also reduces maintenance costs. In addition, the support base and load-bearing platform can be designed in various shapes such as rectangles and circles, giving the device good environmental adaptability and flexibly adapting to different installation spaces and interface requirements. With a purely mechanical passive structure, it successfully achieves low-frequency vibration control that requires no external energy consumption, has a compact structure, is flexible in adjustment, and is highly efficient. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention; Figure 2 This is a top view schematic diagram of the overall structure of the present invention.

[0017] 1. Support base; 2. Load-bearing platform; 3. Profile support column; 4. Sleeve; 5. Cylindrical helical spring; 6. Angle bracket. Detailed Implementation

[0018] The following will be combined with the appendix Figure 1-2 The technical solutions in the embodiments are described clearly and completely.

[0019] Specific implementation method one: as follows Figure 1-2As shown, the vibration isolator includes a support base 1 as a fixed foundation and a support platform 2 for supporting the vibration-isolated equipment. The projected area of ​​the support base 1 is designed to be larger than the projected area of ​​the support platform 2 to enhance the overall stability of the vibration isolator and prevent overturning. Multiple vertically erected profile columns 3 are detachably fixed to the support base 1 by means of angle brackets 6 and bolts, which facilitates the transportation and on-site installation and commissioning of the device. The columns 3 provide the main rigid support frame for the entire vibration isolator. Among them, the positive stiffness mechanism is a rocker mechanism; the rocker mechanism is connected to the rotating shaft fixedly installed on the profile support 3 through the keyway on it to achieve precise fixed-axis rotation; one end of the rocker mechanism (closer to the support 3) rotates around the rotating shaft, and the other end of the rocker mechanism is connected to the upper bearing platform 2 by a hinge; when the bearing platform 2 is subjected to a downward load, the rocker mechanism converts the vertical displacement of the platform into its own rotational motion, and the mechanical characteristics of the rocker mechanism are nonlinear gradually hardening positive stiffness; The negative stiffness mechanism consists of an inclined cylindrical helical spring 5; one end of the cylindrical helical spring 5 is hinged to a profile support 3, and the other end of the cylindrical helical spring 5 is hinged to a bearing platform 2, so that the axis of the cylindrical helical spring 5 is inclined at an angle relative to the horizontal plane; in order to ensure that the cylindrical helical spring 55 always maintains the expected mechanical properties during operation and does not become unstable and bent, the implementation also includes a sleeve 4 sleeved on the cylindrical helical spring 5, the inner diameter of the sleeve 4 being slightly larger than the outer diameter of the spring 5, so as to play a guiding and limiting role; To ensure the stability and consistent performance of the vibration isolator, the rocker mechanism and the inclined cylindrical helical spring 5 are both arranged symmetrically around the center of the bearing platform 2; this symmetrical layout ensures that consistent and effective vibration isolation can be achieved regardless of the direction of the vibration. The adjustable feature of the quasi-zero stiffness vibration isolation platform is that the connection point between the load-bearing platform and the profile support can be adjusted parallel to the force line, and the hinged part of the inclined spring profile can move parallel to the vertical direction along the mating groove. This changes the static characteristics of the structure, and thus the static stiffness, i.e., the load-bearing capacity.

[0020] Workflow: First, the vibration isolation device is installed on the support platform 2. The weight of the device will cause the support platform 2 to sink, compressing the positive stiffness mechanism (rocker mechanism) and stretching the negative stiffness mechanism (cylindrical helical spring 5). The system will then stabilize at a new equilibrium position. By matching the stiffness and installation dimensions of the positive and negative mechanisms, the nonlinear positive stiffness generated by the rocker mechanism and the negative stiffness generated by the cylindrical helical spring 5 can be made equal in magnitude and opposite in direction within a small displacement range near the equilibrium position, thus achieving a state where "dynamic stiffness approaches zero". This range is the "quasi-zero stiffness range" for achieving efficient low-frequency vibration isolation. When low-frequency, slight vibrations from the external environment are transmitted to the support base 1, the vibrations will attempt to be transmitted to the bearing platform 2 and the equipment on it through the profile support column 3. Within the "quasi-zero stiffness range", due to the extremely low dynamic stiffness of the system, the transmission rate is extremely high according to the vibration isolation theory. This means that the vibration of the support base 1 requires a huge force to drive the bearing platform 2 to respond, and most of the vibration energy is "isolated". Specifically, when the support base 1 has an upward vibration displacement, it will generate an upward force on the bearing platform 2 through the rocker mechanism and the cylindrical helical spring 5. However, due to the cancellation of positive and negative stiffness, this force is very small, resulting in the displacement response of the bearing platform 2 being much smaller than the displacement of the support base 1, thereby achieving vibration isolation. The downward vibration process is similar. The sleeve 4 ensures that the cylindrical helical spring 5 deforms axially throughout the process, maintaining the accuracy and stability of the negative stiffness characteristics. The symmetrical layout ensures the consistency of vibration isolation performance in different directions.

[0021] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. An adjustable stiffness quasi-zero stiffness vibration isolator, characterized in that, It includes a support base (1), a load-bearing platform (2), and a support assembly connecting the support base (1) and the load-bearing platform (2); The support components include a positive stiffness mechanism and a negative stiffness mechanism. The positive stiffness mechanism and the negative stiffness mechanism are set in parallel to provide support for the bearing platform (2). The positive stiffness mechanism is a rocker mechanism and the negative stiffness mechanism is an elastic element set at an inclination.

2. The adjustable stiffness quasi-zero stiffness vibration isolator according to claim 1, characterized in that, The support assembly also includes a column (3) vertically erected on the support base (1), and a rocker mechanism is rotatably connected to the column (3), and the rocker mechanism is hinged to the bearing platform (2); the elastic element is a cylindrical helical spring (5), one end of the cylindrical helical spring (5) is hinged to the column (3), and the other end of the cylindrical helical spring (5) is hinged to the bearing platform (2).

3. The adjustable stiffness quasi-zero stiffness vibration isolator according to claim 2, characterized in that, The rocker mechanism and the inclined cylindrical helical spring (5) are both arranged symmetrically with respect to the center of the bearing platform (2).

4. The adjustable stiffness quasi-zero stiffness vibration isolator according to claim 2, characterized in that, It also includes a sleeve (4) fitted outside the cylindrical helical spring (5), and the inner diameter of the sleeve (4) is larger than the outer diameter of the cylindrical helical spring (5).

5. An adjustable stiffness quasi-zero stiffness vibration isolator according to claim 2, characterized in that, The support column (3) is detachably fixed to the support base (1) by means of corner brackets (6) and bolts.

6. The adjustable stiffness quasi-zero stiffness vibration isolator according to claim 1, characterized in that, The projected area of ​​the support base (1) is greater than the projected area of ​​the bearing platform (2).

7. An adjustable stiffness quasi-zero stiffness vibration isolator according to claim 2, characterized in that, The rocker mechanism achieves fixed-axis rotation by engaging with a rotating shaft fixed on the support column (3) via a keyway.

8. The adjustable stiffness quasi-zero stiffness vibration isolator according to claim 1, characterized in that, The support base (1) and the bearing platform (2) are rectangular, circular or polygonal in shape.

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