Quasi-zero stiffness vibration isolator based on springs and variable stiffness electromagnetic units

Abstract

The invention discloses a quasi-zero-stiffness vibration isolator based on springs and variable-stiffness electromagnetic units, belongs to the technical field of low-frequency vibration isolation, and aims at solving the problems that a traditional quasi-zero-stiffness vibration isolator is low in response speed, invariable in adaptive load and free of foundation bearing capacity. The electromagnetic positive stiffness unit and the electromagnetic negative stiffness unit are fixed on the base through hexagonal studs, the magnet unit and the carrying platform are connected through bolts and nuts, the upper end of the linear spring unit is connected with the carrying platform through bolts and nuts, and the quasi-zero stiffness characteristic is achieved through combination of linear springs and the electromagnetic unit. The linear spring unit can provide basic bearing capacity when no current is input, heavy objects with different masses can be borne by adjusting and controlling the current to change the rigidity of the electromagnetic unit, the excellent low-frequency vibration isolation capacity is guaranteed, and the linear spring unit has the advantages of being novel and simple in structure, simple in rigidity adjusting and controlling mode, high in response speed and the like. The method can be widely applied to the fields of precise instruments, aerospace, intelligent equipment and the like.

Description

Technical Field

[0001] The present invention relates to a low-frequency vibration isolator, in particular to a quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit, and belongs to the technical field of low-frequency vibration isolation. Background Art

[0002] In the fields of precision instruments, aerospace, high-end manufacturing, etc., low-frequency vibrations, especially low-frequency disturbances below 5Hz, can seriously affect the operating accuracy, stability and service life of the equipment. Traditional linear vibration isolators have a good inhibitory effect on high-frequency vibrations, but a poor inhibitory effect on low-frequency vibrations. In order to expand the vibration isolation range of the vibration isolator and improve its low-frequency vibration isolation performance, it is necessary to reduce the natural frequency of the system, which will lead to a decrease in the stiffness of the vibration isolator. However, too low stiffness will lead to a decrease in the overall load-bearing capacity of the system. Therefore, traditional linear vibration isolators cannot take into account both low-frequency vibration isolation effects and system load-bearing capacity. Therefore, there is an urgent need to find a vibration isolation method that can resolve this contradiction. Among them, a quasi-zero stiffness vibration isolator that uses a combination of positive and negative stiffness to offset each other to form a system stiffness close to zero while maintaining a high static load-bearing capacity is considered to be an effective key technical direction. To date, quasi-zero stiffness vibration isolators mostly use mechanical structures such as nonlinear springs, cam mechanisms, and magnetic repulsion components to achieve quasi-zero stiffness.

[0003] However, the quasi-zero-stiffness vibration isolators in the existing technology have significant limitations. The design that relies on mechanical structure to achieve positive and negative stiffness often has problems such as complex structure, limited adjustment range, and slow response speed. For example, the literature "Liu F, Liao X, Chen L, Jiao R. Modeling and dynamics of a piecewise quasi-zero-stiffness vibration isolation system with cam[J]. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 2025; 47(4)." is difficult to meet the dynamic adaptation requirements of high-precision equipment for vibration isolation performance.

[0004] Secondly, once the stiffness parameters of the mechanical structure of existing quasi-zero stiffness isolators are finalized, they are difficult to adjust dynamically. For example, in the literature "Zhao F, Ji JC, Cao S, Zheng J, Luo QA constant quasi-zero stiffness isolator with tension springs to isolate vibrations with ultralow frequency[J]. International Journal of Non-Linear Mechanics. 2025; 175.", when the mass of the load changes, such as adding or removing components during equipment operation, the quasi-zero stiffness characteristics of the system will be destroyed, and the low-frequency vibration isolation performance will be significantly reduced.

[0005] Currently, most quasi-zero stiffness isolators constructed based on magnetic repulsion components use only a single electromagnetic unit, such as in the literature "Lu JJ, Yan G, Qi WH, Yan H, Shi JW, Chen A, et al. Load-adaptive quasi-zero stiffness vibration isolation via dual electromagnetic stiffness regulation. Journal of Sound and Vibration. 2023; 567." When the external input current is zero, the electromagnetic unit cannot provide electromagnetic force to offset the load's gravity. The load-bearing components of the vibration isolator will suffer a rigid collision due to loss of support. At this time, the vibration isolator not only fails to isolate vibration, but may also cause damage to itself or the vibration isolation equipment due to structural impact. This risk is particularly significant when carrying large mass loads. Summary of the Invention

[0006] The purpose of the present invention is to provide a quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit to solve the problems of slow response speed, unchangeable adaptive load and no basic bearing capacity of traditional vibration isolators.

[0007] A quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit comprises a linear spring unit, an electromagnetic positive stiffness unit, an electromagnetic negative stiffness unit and a magnet unit;

[0008] The electromagnetic positive stiffness unit and the electromagnetic negative stiffness unit are fixed to the base through the lower hexagonal studs and the upper hexagonal studs, the magnet unit and the loading platform are connected through bolts and nuts, the upper end of the linear spring unit is connected to the loading platform through bolts and nuts, and the optical axis at the lower end can move in the linear bearing connected to the positive stiffness coil base.

[0009] Preferably: the linear spring unit includes a linear bearing, a spring fixing seat, a linear spring, an optical axis and an optical axis fixing seat. The optical axis fixing seat, the loading platform and the optical axis are connected by bolts and nuts. One end of the linear spring is supported under the loading platform and the other end is fixed in the spring fixing seat. The spring fixing seat and the linear bearing are installed on the positive stiffness coil base by bolts and nuts. The optical axis can move up and down in the linear bearing.

[0010] Preferably: the electromagnetic positive stiffness unit includes a positive stiffness coil base, a positive stiffness coil fixing plate, a positive stiffness coil and a positive stiffness four-claw fixer, wherein the positive stiffness coil base is connected to the base through a lower hexagonal stud and a nut, and the positive stiffness coil is installed on the positive stiffness coil fixing plate using the positive stiffness four-claw fixer and bolts and nuts, and the positive stiffness coil fixing plate is fixed to the positive stiffness coil base through bolts and nuts.

[0011] Preferably: the electromagnetic negative stiffness unit includes a negative stiffness coil base, a negative stiffness coil fixing plate, a negative stiffness coil and a negative stiffness four-claw fixer, wherein the negative stiffness coil is fixed to the negative stiffness coil fixing plate using the negative stiffness four-claw fixer and bolts and nuts, the negative stiffness coil fixing plate is fixed to the negative stiffness coil base by bolts and nuts, and the negative stiffness coil base is connected to the positive stiffness coil base by bolts and upper hexagonal studs, that is, connected to the base.

[0012] Preferably, the magnet unit comprises a magnet fixing plate, a magnet and a magnet fixing rod, which are connected by bolts and nuts, and the magnet fixing rod is fixed to the loading platform by bolts and nuts.

[0013] Compared with existing products, the present invention has the following effects:

[0014] 1. A quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit achieves real-time stiffness adjustment through current control of the electromagnetic unit, without the need for mechanical structure adjustment. Its response speed is much faster than that of traditional vibration isolators that rely on mechanical deformation. It has the advantages of a novel and simple overall structure, simple stiffness control method, and fast response speed, and can quickly adapt to dynamic vibration environments.

[0015] 2. The electromagnetic positive and negative stiffness coil units of the present invention can change the stiffness of the electromagnetic units by regulating the current. When the mass of the load carried on the load platform changes, there is no need to replace components. By simply adjusting the stiffness of the electromagnetic units, the system's quasi-zero stiffness characteristics can be re-matched. While the load remains in its initial equilibrium position, the system exhibits a new quasi-zero stiffness characteristic, allowing the vibration isolator to maintain excellent low-frequency vibration isolation capabilities. The vibration isolator has the advantage of maintaining quasi-zero stiffness characteristics over a wide load range.

[0016] 3. The linear spring unit of the present invention is not only used to match the quasi-zero stiffness characteristics of the entire system, but also can provide basic bearing capacity for the entire system when there is no current input, avoiding collision risks while maintaining structural stability. It solves the defect of traditional electromagnetic quasi-zero stiffness isolators without basic bearing capacity and has the advantages of safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of a quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit;

[0018] Figure 2 is an exploded diagram of the linear spring element;

[0019] Figure 3 is an exploded diagram of the electromagnetic positive stiffness unit;

[0020] Figure 4 is an exploded diagram of the electromagnetic negative stiffness unit;

[0021] Figure 5 It is an exploded schematic diagram of the magnet unit;

[0022] Figure 6 This is the wiring diagram of the positive and negative stiffness coils.

[0023] In the figure: 1—linear spring unit, 2—electromagnetic positive stiffness unit, 3—electromagnetic negative stiffness unit, 4—magnet unit, 5—positive stiffness coil base, 6—linear bearing, 7—spring fixing seat, 8—linear spring, 9—optical axis, 10—carrying platform, 11—optical axis fixing seat, 12—base, 13—lower hexagonal stud, 14—positive stiffness coil fixing plate, 15—positive stiffness coil, 16—positive stiffness four-claw fixture, 17—upper hexagonal stud, 18—negative stiffness coil base, 19—negative stiffness coil fixing plate, 20—negative stiffness coil, 21—negative stiffness four-claw fixture, 22—magnet fixing plate, 23—magnet, 24—magnet fixing rod. DETAILED DESCRIPTION

[0024] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] like Figures 1 to 6 As shown, the quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit according to the present invention comprises a linear spring unit 1, an electromagnetic positive stiffness unit 2, an electromagnetic negative stiffness unit 3 and a magnet unit 4;

[0026] The electromagnetic positive stiffness unit 2 and the electromagnetic negative stiffness unit 3 are fixed to the base 12 through the lower hexagonal studs 13 and the upper hexagonal studs 17. The magnet unit 4 and the loading platform 10 are connected by bolts and nuts. The upper end of the linear spring unit 1 is connected to the loading platform 10 through bolts and nuts. The optical axis 9 at the lower end can move in the linear bearing 6 connected to the positive stiffness coil base 5.

[0027] Further: the linear spring unit 1 includes a linear bearing 6, a spring fixing seat 7, a linear spring 8, an optical axis 9 and an optical axis fixing seat 11. The optical axis fixing seat 11, the loading platform 10 and the optical axis 9 are connected by bolts and nuts. One end of the linear spring 8 is supported under the loading platform 10, and the other end is fixed in the spring fixing seat 7. The spring fixing seat 7 and the linear bearing 6 are installed on the positive stiffness coil base 5 by bolts and nuts. The optical axis 9 can move up and down in the linear bearing 6.

[0028] Further: the electromagnetic positive stiffness unit 2 includes a positive stiffness coil base 5, a positive stiffness coil fixing plate 14, a positive stiffness coil 15 and a positive stiffness four-claw fixer 16, wherein the positive stiffness coil base 5 is connected to the base 12 through the lower hexagonal stud 13 and the nut, and the positive stiffness coil 15 is installed on the positive stiffness coil fixing plate 14 using the positive stiffness four-claw fixer 16 and bolts and nuts, and at the same time, the positive stiffness coil fixing plate 14 is fixed to the positive stiffness coil base 5 through bolts and nuts.

[0029] Further: the electromagnetic negative stiffness unit 3 includes a negative stiffness coil base 18, a negative stiffness coil fixing plate 19, a negative stiffness coil 20 and a negative stiffness four-claw fixer 21, wherein the negative stiffness coil 20 is fixed to the negative stiffness coil fixing plate 19 by using the negative stiffness four-claw fixer 21 and bolts and nuts, the negative stiffness coil fixing plate 19 is fixed to the negative stiffness coil base 18 by bolts and nuts, and the negative stiffness coil base 18 is connected to the positive stiffness coil base 5 by bolts and the upper hexagonal studs 17, that is, connected to the base 12.

[0030] Furthermore, the magnet unit 4 includes a magnet fixing plate 22 , a magnet 23 and a magnet fixing rod 24 , which are connected by bolts and nuts. The magnet fixing rod 24 is fixed to the loading platform 10 by bolts and nuts.

[0031] The positive stiffness coil 15 and the negative stiffness coil 20 are both varnished copper wire coils, the outer layers of the varnished copper wires are insulated, and the varnished copper wires are spirally wound clockwise from inside to outside.

[0032] Both the positive stiffness coil 15 and the negative stiffness coil 20 can be directly powered by an external constant current source, and generate electromagnetic force on the magnet 23 in the magnet unit 4. The magnet fixing rod 24 in the magnet unit 4 is fixed to the loading platform 10 by bolts and nuts, so the electromagnetic force directly acts on the loading platform 10 to support heavy objects.

[0033] The lower end of the linear spring 8 in the linear spring unit 1 is installed in the spring fixing seat 7, and the upper end is supported under the loading platform 10, thereby exerting a vertical force on the loading platform 10 to carry heavy objects. At the same time, the upper end of the optical axis 9 matched with the linear bearing 6 is fixed to the loading platform 10 by the optical axis fixing seat 11, thereby ensuring that the loading platform 10 only moves in the vertical direction.

[0034] This embodiment is only an illustrative description of this patent and does not limit its scope of protection. Those skilled in the art may also make partial changes to it, but they do not exceed the spirit of this patent and are all within the scope of protection of this patent.

Claims

1. A quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit, characterized by: It comprises a linear spring unit (1), an electromagnetic positive stiffness unit (2), an electromagnetic negative stiffness unit (3) and a magnet unit (4); The electromagnetic positive stiffness unit (2) and the electromagnetic negative stiffness unit (3) are fixed to the base (12) via a lower hexagonal stud (13) and an upper hexagonal stud (17); the magnet unit (4) and the loading platform (10) are connected via bolts and nuts; the upper end of the linear spring unit (1) is connected to the loading platform (10) via bolts and nuts; and the optical axis (9) at the lower end can move in a linear bearing (6) connected to the positive stiffness coil base (5).

2. The quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit according to claim 1, characterized in that: The linear spring unit (1) comprises a linear bearing (6), a spring fixing seat (7), a linear spring (8), an optical axis (9) and an optical axis fixing seat (11); the optical axis fixing seat (11), the object platform (10) and the optical axis (9) are connected by bolts and nuts; one end of the linear spring (8) is supported below the object platform (10) and the other end is fixed in the spring fixing seat (7); the spring fixing seat (7) and the linear bearing (6) are mounted on a positive stiffness coil base (5) by bolts and nuts; and the optical axis (9) can move up and down in the linear bearing (6).

3. The quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit according to claim 1, characterized in that: The electromagnetic positive stiffness unit (2) comprises a positive stiffness coil base (5), a positive stiffness coil fixing plate (14), a positive stiffness coil (15) and a positive stiffness four-claw fixer (16), wherein the positive stiffness coil base (5) is connected to the base (12) via a lower hexagonal stud (13) and a nut, and the positive stiffness coil (15) is mounted on the positive stiffness coil fixing plate (14) using the positive stiffness four-claw fixer (16) and bolts and nuts, while the positive stiffness coil fixing plate (14) is fixed to the positive stiffness coil base (5) via bolts and nuts.

4. The quasi-zero stiffness vibration isolator based on a spring and a variable stiffness electromagnetic unit according to claim 1, characterized in that: The electromagnetic negative stiffness unit (3) comprises a negative stiffness coil base (18), a negative stiffness coil fixing plate (19), a negative stiffness coil (20) and a negative stiffness four-claw fixer (21), wherein the negative stiffness coil (20) is fixed to the negative stiffness coil fixing plate (19) by using the negative stiffness four-claw fixer (21) and bolts and nuts, the negative stiffness coil fixing plate (19) is fixed to the negative stiffness coil base (18) by bolts and nuts, the negative stiffness coil base (18) is connected to the positive stiffness coil base (5) by bolts and upper hexagonal studs (17), that is, connected to the base (12), the magnet unit (4) comprises a magnet fixing plate (22), a magnet (23) and a magnet fixing rod (24), the three of which are connected by bolts and nuts, and the magnet fixing rod (24) is fixed to the loading platform (10) by bolts and nuts.

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