Negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristic

Abstract

The invention provides a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics, and relates to the technical field of vibration isolation devices. Comprising a bottom plate, a positive stiffness unit and a negative stiffness unit, and the positive stiffness unit comprises a positive stiffness spring and a positive stiffness spring cover plate; the negative stiffness unit comprises a first pressed spring piece, a second pressed spring piece, a third pressed spring piece and a fourth pressed spring piece; a first center plate is arranged between the first pressed spring piece and the second pressed spring piece; a second center plate is arranged between the third pressed spring piece and the fourth pressed spring piece; the first pressed spring piece, the second pressed spring piece, the third pressed spring piece, the fourth pressed spring piece, the first center plate, the second center plate and the positive stiffness spring cover plate are stacked in the vertical direction. Vibration transmission between an object and the base can be effectively reduced, the size of the device is reduced, the vibration isolation performance is not affected, compact design is achieved, and the requirements of some special vibration reduction systems are met.

Description

Technical Field

[0001] The invention relates to the technical field of vibration isolation devices, and in particular to a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics. Background Art

[0002] In the engineering field, vibration affects the comfort of use, reduces the accuracy and stability of precision equipment, and even causes structural fatigue damage. Previous studies have widely discussed the problems caused by vibration on equipment and devices with extremely high motion sensitivity, and proposed many measures to reduce vibration propagation. However, the natural frequency of the vibration isolation system based on the traditional linear vibration isolation method is relatively high, and there are obvious defects in isolating low-frequency vibration.

[0003] Unlike traditional linear vibration isolation methods, quasi-zero stiffness vibration isolation technology can significantly reduce dynamic stiffness without reducing static stiffness. This nonlinear characteristic of low dynamic stiffness and high static stiffness can reduce the starting vibration isolation frequency of the vibration isolation system while ensuring a high load-bearing capacity, thereby expanding the vibration isolation frequency band to the low-frequency region. By selecting appropriate system parameters, the positive stiffness unit and the negative stiffness unit are connected in parallel to achieve quasi-zero stiffness characteristics. At present, some quasi-zero stiffness isolators have been applied in the engineering field and have shown greater superiority than linear vibration isolation methods.

[0004] However, the quasi-zero stiffness isolators currently constructed based on geometric nonlinearity, magnetic nonlinearity and other elements are large in size, cannot meet the requirements of some vibration reduction systems, and have limited application scenarios. Summary of the invention

[0005] The purpose of the present invention is to provide a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics, which can effectively reduce the vibration transmission between the object and the base, and has the nonlinear characteristics of low dynamic stiffness and high static stiffness. While ensuring a high load-bearing capacity, the natural frequency of the vibration isolation system is greatly reduced, thereby expanding the vibration isolation frequency band to the low-frequency region; wherein, the stiffness of the negative stiffness unit can be adjusted by a cable to adapt to different loads; at the same time, the stacked arrangement of compressed spring sheets can reduce the size of the device without affecting the vibration isolation performance, thereby achieving a compact design and meeting the requirements of some special vibration reduction systems.

[0006] The technical solution adopted by the present invention is:

[0007] The embodiment of the present application provides a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics, comprising a base plate, a positive stiffness unit and a negative stiffness unit, wherein the positive stiffness unit comprises a plurality of positive stiffness springs vertically arranged on the top of the base plate and a positive stiffness spring cover plate arranged on the top of the positive stiffness spring;

[0008] The negative stiffness unit includes a first compressed spring sheet, a second compressed spring sheet, a third compressed spring sheet, and a fourth compressed spring sheet; a bottom rigid plate is provided on the top of the bottom plate, a top rigid plate is provided on the top of the bottom rigid plate, a flexible plate is provided opposite to the top rigid plate, and the negative stiffness unit is located between the top rigid plate and the flexible plate;

[0009] The first compression spring sheet is located above the second compression spring sheet, and a first center plate is provided between the first compression spring sheet and the second compression spring sheet; one end of the first compression spring sheet is fixed to the top of the top rigid plate, and the other end of the first compression spring sheet is fixed to the top of the first center plate; one end of the second compression spring sheet is fixed to the bottom of the first center plate, and the other end of the second compression spring sheet is fixed to the top of the flexible plate;

[0010] The third compressed spring piece is located below the second compressed spring piece and above the fourth compressed spring piece, and a second center plate is provided between the third compressed spring piece and the fourth compressed spring piece; one end of the third compressed spring piece is fixed to the bottom of the flexible plate, and the other end of the third compressed spring piece is fixed to the top of the second center plate; one end of the fourth compressed spring piece is fixed to the bottom of the second center plate, and the other end of the fourth compressed spring piece is fixed between the bottom rigid plate and the top rigid plate;

[0011] The fourth compressed spring sheet is located above the positive stiffness spring cover plate, and the first compressed spring sheet, the second compressed spring sheet, the third compressed spring sheet, the fourth compressed spring sheet, the first center plate, the second center plate and the positive stiffness spring cover plate are stacked in the vertical direction; the device also includes a side plate, and the first center plate, the second center plate and the positive stiffness spring cover plate are all fixedly arranged on the side plate.

[0012] Furthermore, in some embodiments of the present invention, the negative stiffness unit also includes a negative stiffness spring and a cable, a mounting sleeve is fixedly provided on one side of the flexible plate close to the top rigid plate, a limiting slider is slidably provided on the flexible plate, and one end of the limiting slider is slidably embedded in the mounting sleeve; the negative stiffness spring is located in the mounting sleeve, one end of the negative stiffness spring abuts against the limiting slider, and the other end of the negative stiffness spring abuts against the mounting sleeve; one end of the cable slides through the mounting sleeve and is connected to the limiting slider, and the other end of the cable is provided with an adjusting slider, and the adjusting slider is slidably arranged on the top rigid plate.

[0013] Furthermore, in some embodiments of the present invention, an adjusting bolt is provided on the outward side of the top rigid plate, and one end of the adjusting bolt passes through the top rigid plate and is threadedly connected to the adjusting slider.

[0014] Furthermore, in some embodiments of the present invention, a U-shaped limiting guide is provided on the inward side of the top rigid plate, the cross-section of the adjusting slider is polygonal, the adjusting slider is slidably arranged in the limiting guide, and the cable slides through the limiting guide.

[0015] Furthermore, in some embodiments of the present invention, gaskets are provided between the first compression spring sheet and the first center plate, between the second compression spring sheet and the first center plate, between the third compression spring sheet and the second center plate, and between the fourth compression spring sheet and the second center plate.

[0016] Furthermore, in some embodiments of the present invention, a rubber sheet is provided between the flexible plate and the bottom plate.

[0017] Furthermore, in some embodiments of the present invention, there are two side panels which are arranged opposite to each other, the negative stiffness unit is located between the two side panels, and a top panel is provided on top of the side panels.

[0018] Furthermore, in some embodiments of the present invention, a shell is provided on the top of the base plate, and the positive stiffness unit and the negative stiffness unit are both provided in the shell.

[0019] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0020] The embodiment of the present invention provides a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics, which can effectively reduce the vibration transmission between an object and a base, and has nonlinear characteristics of low dynamic stiffness and high static stiffness. While ensuring a high load-bearing capacity, the natural frequency of the vibration isolation system is greatly reduced, thereby expanding the vibration isolation frequency band to the low-frequency region; wherein, the stiffness of the negative stiffness unit can be adjusted by a cable to adapt to different loads; at the same time, the stacked arrangement of compressed spring sheets can reduce the size of the device without affecting the vibration isolation performance, thereby achieving a compact design and meeting the requirements of some special vibration reduction systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the structure of a vibration isolation device provided in an embodiment of the present invention;

[0023] Figure 2 A partial cross-sectional view of the vibration isolation device provided by an embodiment of the present invention after the side plate is removed;

[0024] Figure 3 Schematic diagram of the internal structure of the vibration isolation device provided in the embodiment of the present invention Figure 1 ;

[0025] Figure 4Schematic diagram of the internal structure of the vibration isolation device provided in the embodiment of the present invention Figure 2 ;

[0026] Figure 5 A front view of the interior of a vibration isolation device provided by an embodiment of the present invention;

[0027] Figure 6 for Figure 4 The schematic diagram of the structure after removing the side panels;

[0028] Figure 7 A schematic diagram of the structure of the cable position provided in an embodiment of the present invention Figure 1 ;

[0029] Figure 8 A schematic diagram of the structure of the cable position provided in an embodiment of the present invention Figure 2 ;

[0030] Fig. 9 A schematic diagram of a vibration isolation device provided in an embodiment of the present invention.

[0031] Icons: 1-bottom plate; 2-positive stiffness spring; 3-positive stiffness spring cover plate; 4-bottom rigid plate; 5-top rigid plate; 6-flexible plate; 7-side plate; 8-top plate; 9-housing; 10-rubber sheet; 11-gasket; 41-first compression spring sheet; 42-second compression spring sheet; 43-third compression spring sheet; 44-fourth compression spring sheet; 45-first center plate; 46-second center plate; 51-negative stiffness spring; 52-cable; 53-installing sleeve; 54-limiting slider; 55-adjusting slider; 56-adjusting bolt; 57-limiting guide; 58-bolt washer. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0035] In the description of the embodiments of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, or are the orientation or position relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc., if used, are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In addition, the use of terms such as "horizontal" and "vertical" does not mean that the components must be absolutely horizontal or vertical, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] Example

[0039] Please refer to Figure 1-Figure 8 This embodiment provides a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics, including a base plate 1, a positive stiffness unit and a negative stiffness unit, the positive stiffness unit includes a plurality of identical positive stiffness springs 2 vertically arranged on the top of the base plate 1 and a positive stiffness spring cover plate 3 arranged on the top of the positive stiffness spring 2, the positive stiffness spring 2 has a supporting capacity in the vertical direction and provides positive stiffness. The number of positive stiffness springs 2 can be adjusted, and the dispersed arrangement of multiple positive stiffness springs 2 can increase the stability of the device and make the structure have a certain anti-overturning ability.

[0040] The positive stiffness springs 2 of this embodiment are four and dispersedly arranged, and the structure is more stable. For the convenience of connection, both ends of the positive stiffness spring 2 are cut into planes, one end is connected to the bottom plate 1, and the other end is connected to the positive stiffness spring cover plate 3. The bottom plate 1 and the positive stiffness spring cover plate 3 are both provided with grooves on the side in contact with the positive stiffness spring 2, and the number and position of the grooves correspond to the positive stiffness spring 2, for placing the positive stiffness spring 2.

[0041] The negative stiffness unit includes a first compression spring sheet 41, a second compression spring sheet 42, a third compression spring sheet 43, and a fourth compression spring sheet 44, each compression spring sheet is arranged horizontally; a bottom rigid plate 4 is arranged on the top of the bottom plate 1, a top rigid plate 5 is arranged on the top of the bottom rigid plate 4, a flexible plate 6 is arranged opposite to the top rigid plate 5, and the negative stiffness unit is located between the top rigid plate 5 and the flexible plate 6;

[0042] The first compression spring piece 41 is located above the second compression spring piece 42, and a first center plate 45 is provided between the first compression spring piece 41 and the second compression spring piece 42; one end of the first compression spring piece 41 is fixed to the top of the top rigid plate 5, and the other end of the first compression spring piece 41 is fixed to the top of the first center plate 45; one end of the second compression spring piece 42 is fixed to the bottom of the first center plate 45, and the other end of the second compression spring piece 42 is fixed to the top of the flexible plate 6;

[0043] The third compression spring piece 43 is located below the second compression spring piece 42 and above the fourth compression spring piece 44, and a second center plate 46 is provided between the third compression spring piece 43 and the fourth compression spring piece 44; one end of the third compression spring piece 43 is fixed to the bottom of the flexible plate 6, and the other end of the third compression spring piece 43 is fixed to the top of the second center plate 46; one end of the fourth compression spring piece 44 is fixed to the bottom of the second center plate 46, and the other end of the fourth compression spring piece 44 is fixed between the bottom rigid plate 4 and the top rigid plate 5;

[0044] The fourth compression spring sheet 44 is located above the positive stiffness spring cover plate 3, and the first compression spring sheet 41, the second compression spring sheet 42, the third compression spring sheet 43, the fourth compression spring sheet 44, the first center plate 45, the second center plate 46 and the positive stiffness spring cover plate 3 are stacked in the vertical direction; it also includes a side plate 7, and the first center plate 45, the second center plate 46 and the positive stiffness spring cover plate 3 are all fixedly arranged on the side plate 7. There are two side plates 7 and they are arranged oppositely. The negative stiffness unit is located between the two side plates 7, and a top plate 8 is provided on the top of the side plate 7. A shell 9 is provided on the top of the bottom plate 1, and bolt holes are provided on the bottom plate 1 for connecting the shell 9. The positive stiffness unit and the negative stiffness unit are both arranged in the shell 9. By connecting the bottom plate 1 and the shell 9 with bolts, the vibration isolation device can be closed to prevent dust and other impurities from entering the vibration isolation device.

[0045] In some embodiments of the present invention, the negative stiffness unit further includes a negative stiffness spring 51 and a cable 52. A mounting sleeve 53 is fixedly provided on one side of the flexible plate 6 close to the top rigid plate 5. A limit slider 54 is slidably provided on the flexible plate 6. One end of the limit slider 54 is slidably embedded in the mounting sleeve 53. The negative stiffness spring 51 is located in the mounting sleeve 53, and its two ends are also cut into planes. One end of the negative stiffness spring 51 abuts against the limit slider 54, and the other end of the negative stiffness spring 51 abuts against the mounting sleeve 53. One end of the cable 52 slides through the mounting sleeve 53 and is connected to the limit slider 54. The other end of the cable 52 is provided with an adjustment slider 55, and the adjustment slider 55 is slidably provided on the top rigid plate 5.

[0046] An adjusting bolt 56 is provided on the outward side of the top rigid plate 5. One end of the adjusting bolt 56 passes through the top rigid plate 5 and is threadedly connected to the adjusting slider 55. The side with the adjusting slider 55 is the adjusting end. When the adjusting bolt 56 at this end is turned, Figure 2 As shown, the cable 52 will pull the limit slider 54 to slide to the right, compressing the negative stiffness spring 51, thereby changing the pressure on the negative stiffness spring 51. The cable 52 is used to adjust the negative stiffness spring 51 without introducing unknown stiffness to the structure. When the vibration isolation device moves in the vertical direction, each compressed spring leaf can bend on the vertical plane, and the compressed spring leaf has negative stiffness, thereby eliminating the positive stiffness of the positive stiffness spring 2 and achieving a quasi-zero stiffness characteristic.

[0047] The thickness of each compressed spring sheet in the embodiment is usually much smaller than at least a portion of its length or width in the vertical direction, so when the vibration isolation device moves in the vertical direction, the compressed spring sheet can bend in the vertical plane. At least a portion of each compressed spring sheet is stacked to meet the compact design requirements.

[0048] The negative stiffness adjustable vertical vibration isolation device based on the quasi-zero stiffness characteristic provided in the present application is used to reduce the propagation of axial or vertical vibration between an object and a support, and the top plate 8 is used to support the object to be isolated. When the top plate 8 is under pressure, the force can be transmitted through the side plate 7 to cause each compressed spring sheet to deform. The deformation of the compressed spring sheet and the negative stiffness spring 51 can generate negative stiffness, which offsets the stiffness of the positive stiffness spring 2, thereby achieving a quasi-zero stiffness characteristic.

[0049] The principle of the quasi-zero stiffness vibration isolation device is as follows Fig. 9 As shown:

[0050] Among them, the total stiffness of the quasi-zero stiffness vibration isolation device is K = K p +K n . Where K p is the stiffness value of the positive stiffness unit, K p >0;K n is the stiffness value of the negative stiffness unit, Kn <0.

[0051] When the deformation of the positive stiffness unit is x0, a negative stiffness unit is connected in parallel in a neighborhood of x0 to adjust the K n Value | K p ∣≈∣K n ∣, then the total stiffness of the quasi-zero stiffness vibration isolation device approaches 0. The quasi-zero stiffness characteristic enables the vibration isolation device to achieve low dynamic stiffness while ensuring high static stiffness. The total load deformation curve of the quasi-zero stiffness vibration isolation system is as follows: Fig. 9 Shown as the solid line segment OABC.

[0052] The device can also be connected with vibration isolation devices in other directions to achieve multi-directional vibration isolation.

[0053] In this way, the vibration isolation device provided by the present application can effectively reduce the vibration transmission between the object and the base, and the device has the nonlinear characteristics of low dynamic stiffness and high static stiffness. While ensuring a high load-bearing capacity, it greatly reduces the natural frequency of the vibration isolation system, thereby expanding the vibration isolation frequency band to the low-frequency region; wherein, the stiffness of the negative stiffness unit can be adjusted by a cable to adapt to different loads; at the same time, through the stacking arrangement of the compressed spring sheets, the size of the device can be reduced without affecting the vibration isolation performance, thereby achieving a compact design and meeting the requirements of some special vibration reduction systems.

[0054] like Figure 1-Figure 8 As shown, in some embodiments of the present invention, a U-shaped limiting guide member 57 is provided on the inner side of the top rigid plate 5, the cross-section of the adjusting slider 55 is polygonal, the adjusting slider 55 is slidably arranged in the limiting guide member 57, and the cable 52 slides through the limiting guide member 57.

[0055] The present invention provides a limiting guide 57, and the adjusting slider 55 can be in a rectangular shape, so that the adjusting slider 55 can be prevented from rotating relative to the top rigid plate 5, thereby ensuring that the cable 52 is not subjected to torque when moving during the process of rotating the adjusting bolt 56 to adjust the cable 52. The adjusting bolt 56 of this embodiment can be sleeved with a plurality of bolt washers 58.

[0056] like Figure 1-Figure 8 As shown, in some embodiments of the present invention, a gasket 11 is provided between the first compression spring sheet 41 and the first center plate 45, between the second compression spring sheet 42 and the first center plate 45, between the third compression spring sheet 43 and the second center plate 46, and between the fourth compression spring sheet 44 and the second center plate 46. The gasket 11 can make the pressure distribution more uniform, thereby improving the fastening effect.

[0057] like Figure 1-Figure 8As shown, in some embodiments of the present invention, a rubber sheet 10 is provided between the flexible plate 6 and the bottom plate 1. The two ends of the rubber sheet 10 are bonded to the flexible plate 6 and the bottom plate 1 respectively. When the compressed spring sheet is slightly shortened or extended in the axial or compression direction, the rubber sheet 10 may be deformed. The rubber sheet 10 is used to cover dust and is not subjected to force.

[0058] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application.

[0059] Therefore, no matter from which point of view, the embodiments should be regarded as illustrative rather than restrictive, and the scope of the present application is limited by the appended claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics, characterized in that: It comprises a bottom plate, a positive stiffness unit and a negative stiffness unit, wherein the positive stiffness unit comprises a plurality of positive stiffness springs vertically arranged on the top of the bottom plate and a positive stiffness spring cover plate arranged on the top of the positive stiffness spring; The negative stiffness unit comprises a first compressed spring sheet, a second compressed spring sheet, a third compressed spring sheet, and a fourth compressed spring sheet; a bottom rigid plate is provided on the top of the bottom plate, a top rigid plate is provided on the top of the bottom rigid plate, a flexible plate is provided opposite to the top rigid plate, and the negative stiffness unit is located between the top rigid plate and the flexible plate; The first compression spring piece is located above the second compression spring piece, and a first center plate is provided between the first compression spring piece and the second compression spring piece; one end of the first compression spring piece is fixed to the top of the top rigid plate, and the other end of the first compression spring piece is fixed to the top of the first center plate; one end of the second compression spring piece is fixed to the bottom of the first center plate, and the other end of the second compression spring piece is fixed to the top of the flexible plate; The third compressed spring piece is located below the second compressed spring piece and above the fourth compressed spring piece, and a second center plate is provided between the third compressed spring piece and the fourth compressed spring piece; one end of the third compressed spring piece is fixed to the bottom of the flexible plate, and the other end of the third compressed spring piece is fixed to the top of the second center plate; one end of the fourth compressed spring piece is fixed to the bottom of the second center plate, and the other end of the fourth compressed spring piece is fixed between the bottom rigid plate and the top rigid plate; The fourth compression spring sheet is located above the positive stiffness spring cover plate, and the first compression spring sheet, the second compression spring sheet, the third compression spring sheet, the fourth compression spring sheet, the first center plate, the second center plate and the positive stiffness spring cover plate are stacked in the vertical direction; it also includes a side plate, and the first center plate, the second center plate and the positive stiffness spring cover plate are all fixed on the side plate.

2. According to claim 1, a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics is characterized by: The negative stiffness unit also includes a negative stiffness spring and a cable. A mounting sleeve is fixedly provided on one side of the flexible plate close to the top rigid plate. A limiting slider is slidably provided on the flexible plate. One end of the limiting slider is slidably embedded in the mounting sleeve. The negative stiffness spring is located in the mounting sleeve. One end of the negative stiffness spring abuts against the limiting slider, and the other end of the negative stiffness spring abuts against the mounting sleeve. One end of the cable slides through the mounting sleeve and is connected to the limiting slider. The other end of the cable is provided with an adjusting slider, and the adjusting slider is slidably arranged on the top rigid plate.

3. According to claim 2, a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics is characterized by: An adjusting bolt is disposed on an outward side of the top rigid plate, and one end of the adjusting bolt passes through the top rigid plate and is threadedly connected to the adjusting slider.

4. According to claim 3, a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics is characterized by: A U-shaped limiting guide is provided on the inner side of the top rigid plate. The cross section of the adjusting slider is a polygon. The adjusting slider is slidably arranged in the limiting guide, and the cable slides through the limiting guide.

5. According to claim 1, a negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics is characterized by: Gaskets are provided between the first compression spring piece and the first center plate, between the second compression spring piece and the first center plate, between the third compression spring piece and the second center plate, and between the fourth compression spring piece and the second center plate.

6. The negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics according to claim 1 is characterized in that: A rubber sheet is arranged between the flexible plate and the bottom plate.

7. The negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics according to claim 1, characterized in that: There are two side panels which are arranged opposite to each other, the negative stiffness unit is located between the two side panels, and a top panel is provided on the top of the side panels.

8. The negative stiffness adjustable vertical vibration isolation device based on quasi-zero stiffness characteristics according to claim 1, characterized in that: A shell is provided on the top of the bottom plate, and the positive stiffness unit and the negative stiffness unit are both provided in the shell.

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