A multi-stage vibration isolation device

Abstract

This solution belongs to the field of low-frequency vibration isolation technology and discloses a multi-stage vibration isolation device, including a first platform and a second platform that are parallel to each other, and a positive stiffness spring and a negative stiffness spring disposed between the first platform and the second platform. The positive stiffness spring is perpendicular to the first / second platform, and the negative stiffness spring is parallel to the first / second platform. The positive and negative stiffness springs are connected in parallel with the second gear and rack mechanism through a symmetrically arranged first gear and rack mechanism. When the rack moves downward by half a circumference of the gear pitch circle, the quasi-zero stiffness region of the vibration isolation device will appear cyclically, which can effectively isolate vibrations for various different loads. The effective load of the vibration isolation device can be easily adjusted by adjusting the relative position of the first support and the second support without replacing any parts. The dimensionless load-displacement multi-platform curve of the vibration isolation device can be arbitrarily customized, and effective vibration isolation can be achieved for any load within the load-bearing range.

Description

Technical Field

[0001] This solution belongs to the field of low-frequency vibration isolation technology, specifically involving a multi-stage vibration isolation device. Background Technology

[0002] Quasi-zero stiffness (QZS) vibration isolators possess advantages such as high load-bearing capacity, wide isolation frequency band, and low natural frequency. Without sacrificing load-bearing capacity, their overall dynamic stiffness is almost zero within the effective operating range, showing broad application prospects in ultra-low frequency vibration isolation. They can overcome the shortcomings of linear vibration isolators in meeting low-frequency isolation requirements and are one of the hot research topics in vibration control. A quasi-zero stiffness vibration isolator is a vibration isolation platform with high static stiffness and low dynamic stiffness. High static stiffness implies high load-bearing capacity or small static load deformation, while low dynamic stiffness indicates a low or near-zero natural frequency. Vibration isolators with these characteristics primarily address the following problems arising from traditional linear vibration isolators composed of mass m and stiffness k: the effective isolation frequency of linear vibration isolators is greater than... The natural frequency is twice that of a linear damper. Therefore, to obtain a wider vibration isolation frequency band, the stiffness k of the linear damper needs to be infinitely small (the natural frequency needs to be closer to 0), but this would cause extremely large static deformation. Therefore, quasi-zero stiffness dampers with high static stiffness and low dynamic stiffness have been developed.

[0003] The main idea behind designing QZS vibration isolators is to introduce a negative stiffness mechanism to counteract the positive stiffness of the elastic element, making the dynamic stiffness zero, while maintaining a high static load-bearing capacity. Therefore, the design of the negative stiffness mechanism is one of the most important aspects of research on quasi-zero stiffness vibration isolators. Domestic and international scholars have conducted extensive research on the design of passive negative stiffness mechanisms, which can be broadly categorized into three types: spring-based, geometrically nonlinear, and magnetic structure-based. These can be further subdivided into seven categories: negative stiffness mechanisms composed of linear springs, negative stiffness mechanisms using buckling beam structures, negative stiffness mechanisms using air springs, negative stiffness mechanisms using geometrically nonlinear structures, negative stiffness mechanisms using disc springs, negative stiffness mechanisms using magnetic springs, and other novel hybrid mechanisms.

[0004] A plateau can be observed on the force-displacement curve of the QZS isolator, indicating that the force is almost constant within an effective displacement range, and the corresponding dynamic stiffness is zero. Here, the force corresponding to the plateau is called the effective load of the QZS. When the isolator is loaded with the effective load, it is compressed to the plateau section, and the dynamic stiffness of the isolator becomes zero, resulting in excellent low-frequency and even ultra-low-frequency vibration isolation. Currently, most QZS isolators are implemented by connecting positive and negative stiffness elements in parallel. Based on this mechanism, QZS isolators typically have only a single effective operating range, resulting in a uniquely determined mass of the isolated object (i.e., the QZS effective load). When the QZS isolator is underloaded or overloaded, its vibration isolation effect is significantly weakened. Summary of the Invention

[0005] To address the problem that existing quasi-zero stiffness vibration isolators typically only have a single effective load and their vibration isolation effect is significantly reduced for non-effective loads, this solution utilizes the transmission characteristics of gears and racks to propose a multi-stage vibration isolation device based on the gear and rack transmission principle. This solves the problem that a single quasi-zero stiffness system has poor vibration isolation and damping characteristics for different masses.

[0006] To solve the above-mentioned technical problems, the following technical solution is adopted:

[0007] A multi-stage vibration isolation device includes a first platform and a second platform that are parallel to each other, and a positive stiffness spring and a negative stiffness spring disposed between the first platform and the second platform. The positive stiffness spring is perpendicular to the first platform / second platform, and the negative stiffness spring is parallel to the first platform / second platform. The positive stiffness spring and the negative stiffness spring are connected in parallel to a first gear and a second gear and a rack mechanism that are symmetrically arranged. The first gear and rack mechanism includes a first gear and a first rack that mesh with each other, and the second gear and rack mechanism includes a second gear and a second rack that mesh with each other. The tooth surfaces of the first rack and the second rack are arranged opposite to each other or back to back, and one end of the rack is connected to the first platform, and the other end of the rack is connected to one end of the positive stiffness spring. The other end of the positive stiffness spring is connected to the second platform. The shafts of the first gear and the second gear are both mounted on the second platform. The shaft of the first gear is driven by a first drive shaft parallel to it, and the shaft of the second gear is driven by a second drive shaft parallel to it. The two ends of the negative stiffness spring are driven by the first drive shaft and the second drive shaft, respectively.

[0008] This device uses a rack and pinion transmission with a negative stiffness spring as the negative stiffness elastic element. As the rack moves downward, the gear rotates. When the gear rotates to an integer multiple of 180°, a new quasi-zero stiffness region appears. The loaded mass and the downward movement of the rack can be completely converted into each other. This means that the quasi-zero stiffness region of the vibration isolation device will appear cyclically every time the rack moves downward by half the circumference of the gear pitch circle. The dimensionless load-displacement curve of the device shows that the platform segment will appear continuously in a cycle, and the dimensionless stiffness-displacement curve shows that the quasi-zero stiffness region will appear continuously in a cycle. This indicates that the device can effectively isolate vibrations for a variety of different loads. Secondly, the effective load of the vibration isolation device can be easily adjusted by changing the relative position of the first and second supports without replacing any parts. The dimensionless load-displacement multi-platform curve of the vibration isolation device can be arbitrarily customized. From the dimensionless load-displacement curves before and after the adjustment, it can be observed that the height of the platform can be continuously changed within the load range by adjustment, which means that the device can effectively isolate any load within the load range by adjustment.

[0009] At least one end of the negative stiffness spring is axially adjustable via a spring fixing assembly to a first drive shaft and / or a second drive shaft, thereby adjusting the pre-compression or pre-tension of the negative stiffness spring. Preferably, the spring fixing assembly includes a first connector and a second connector. One end of the first connector is fixedly connected to the negative stiffness spring, and the other end has an internal thread. One end of the second connector has an external thread, and the other end is axially connected to the first drive shaft and / or the second drive shaft. The internal thread of the first connector mates with the external thread of the second connector. Alternatively, the spring fixing assembly includes a first connector and a second connector. One end of the first connector is fixedly connected to the negative stiffness spring, and the other end has an external thread. One end of the second connector has an internal thread, and the other end is axially connected to the first drive shaft and / or the second drive shaft. The external thread of the first connector mates with the internal thread of the second connector. Adjusting the mating length between the external and internal threads adjusts the extension / retraction of the spring fixing assembly, thereby adjusting the pre-compression or pre-tension of the negative stiffness spring.

[0010] The first drive shaft is connected to the shaft of the first gear via an eccentric disk, or the second drive shaft is connected to the shaft of the second gear via an eccentric disk, or the first and second drive shafts are respectively connected to the shaft of the first gear via eccentric disks. The eccentric disk has a central hole and an eccentric hole. The central hole is connected to the shaft of the first gear and / or the second gear. The eccentric hole is an elongated hole, with its centerline passing through the center of the central hole along its length. The first drive shaft and / or the second drive shaft are fixedly connected to the elongated hole by fasteners. Adjusting the relative position of the first drive shaft and / or the second drive shaft with respect to the elongated hole adjusts the relative position of the first drive shaft and the shaft of the first gear. The central hole is a splined hole, and the shaft of the first gear and / or the second gear has a spline that mates with it to achieve circumferential positioning of the shaft of the first gear and the eccentric disk.

[0011] The shafts of both the first and second gears are mounted on the second platform via height-adjustable gear mounting brackets, allowing adjustment of the relative height between the first and second gears and the second platform before fastening. Preferably, the gear mounting bracket includes a rod-shaped first support and a cylindrical second support. The second support is sleeved outside the first support, and its side wall has threaded holes. Fasteners abutting against the side of the first support are connected to these threaded holes, allowing adjustment of the relative height between the gears and the second platform by adjusting the relative positions of the first and second supports. The shafts of the first and second gears are mounted on the free ends of the first support, and the free ends of the second support are fixed to the second platform.

[0012] The first platform is provided with a guide hole, and the second platform is fixed with a guide rod that mates with the guide hole to achieve the guiding function of the device in the direction perpendicular to the first platform / second platform. Preferably, one end of the first rack and the second rack are fixed to the first platform by a first rack fixing member, and the other end is fixedly connected to a positive stiffness spring by a second rack fixing member. Both the first rack fixing member and the second rack fixing member are provided with guide holes that mate with the guide rod, so as to better achieve the guiding function of each component in the device in the direction perpendicular to the first platform / second platform. More preferably, a linear bearing that mates with the guide rod is installed in the guide holes of the first rack fixing member and the second rack fixing member.

[0013] Compared with existing technologies, this solution offers the following advantages: This device utilizes a rack and pinion transmission with a negative stiffness spring as the negative stiffness elastic element. As the rack moves downwards, the gear rotates. New quasi-zero stiffness regions appear whenever the gear rotates to an integer multiple of 180°. The loaded mass and the downward movement of the rack are completely interchangeable. This means that the quasi-zero stiffness region of the vibration isolation device cyclically appears every time the rack moves downwards by half the pitch circle of the gear, effectively isolating various loads. Secondly, the effective load of the vibration isolation device can be easily adjusted by changing the relative positions of the first and second supports without replacing any parts. The dimensionless load-displacement multi-platform curve of the vibration isolation device can be arbitrarily customized, enabling effective vibration isolation of any load within its load-bearing range. Attached Figure Description

[0014] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this solution. To better illustrate the solution, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0015] Figure 1 This is an isometric view of a multi-stage vibration isolation device;

[0016] Figure 2 This is a two-dimensional front view of a multi-stage vibration isolation device;

[0017] Figure 3 This is a two-dimensional left view of a multi-stage vibration isolation device;

[0018] Figure 4 This is a two-dimensional top view of a multi-stage vibration isolation device;

[0019] Figure 5 It is the dimensionless bearing capacity-displacement curve of a multi-stage vibration isolation device;

[0020] Figure 6 It is the dimensionless stiffness-displacement curve of a multi-stage vibration isolation device;

[0021] Figure 7 It is a dimensionless bearing capacity-displacement curve before and after adjustment of the multi-stage vibration isolation device.

[0022] Explanation of reference numerals in the attached drawings: First platform 100, Second platform 200, Positive stiffness spring 300, First spring fixing member 310, Second spring fixing member 320, Negative stiffness spring 400, Third spring fixing member 410, Fourth spring fixing member 420, First connecting member 421, Second connecting member 422, First gear and rack mechanism 510, First gear 511, First rack 512, Second gear and rack mechanism 520, Second gear 521, Second rack 522, Gear shaft 530, First support 541, Second support 542, Bearing base 551, Bearing upper cover 552, Bearing end cover 553, Second bearing 554, First sleeve 555, Second sleeve 556, First rack fixing member 561, Second rack fixing member 562, First drive shaft 610, Second drive shaft 620, Eccentric disc 630, Center hole 631, Eccentric hole 632, Guide rod 700. Detailed Implementation

[0023] To enable those skilled in the art to better understand this solution, the following detailed description is provided in conjunction with specific embodiments.

[0024] Figures 1-4 An embodiment of a multi-stage vibration isolation device is shown. In this embodiment, the multi-stage vibration isolation device includes a first platform 100 and a second platform 200 that are parallel to each other, and a positive stiffness spring 300 and a negative stiffness spring 400 disposed between the first platform 100 and the second platform 200. The positive stiffness spring 300 is perpendicular to the first platform 100 / second platform 200, and the negative stiffness spring 400 is parallel to the first platform 100 / second platform 200.

[0025] The positive stiffness spring 300 and the negative stiffness spring 400 are connected in parallel through a first gear 511 rack mechanism 510 and a second gear 521 rack mechanism 520, which are symmetrically arranged. The first gear 511 rack mechanism 510 includes a first gear 511 and a first rack 512 meshing with each other, and the second gear 521 rack mechanism 520 includes a second gear 521 and a second rack 522 meshing with each other; the tooth surfaces of the first rack 512 and the second rack 522 are arranged opposite to or away from each other, and one end is connected to the first platform 100, and the other end is connected to one end of the positive stiffness spring 300, the other end of the positive stiffness spring 300 is connected to the second platform 200; the shafts of the first gear 511 and the second gear 521 are both mounted on the second platform 200, the shaft of the first gear 511 is driven by a first drive shaft 610 parallel to it, the shaft of the second gear 521 is driven by a second drive shaft 620 parallel to it, and the two ends of the negative stiffness spring 400 are respectively driven by the first drive shaft 610 and the second drive shaft 620.

[0026] The positive stiffness spring 300 has a first spring fixing member 310 and a second spring fixing member 320 at both ends. Both the first spring fixing member 310 and the second spring fixing member 320 have slots on the side facing the positive stiffness spring 300. Both ends of the positive stiffness spring 300 are fixed in these slots, allowing the positive stiffness spring 300 to be subjected to both compression and tension during operation. The first spring fixing member 310 connects to the first rack 512 and the second rack 522, and the second spring fixing member 320 is fixed to the second platform 200. This achieves one end of the positive stiffness spring 300 connected to the first rack 512 and the second rack 522, and the other end fixed to the second platform 200. The second spring fixing member 320 can be fastened to the threaded hole at the center of the second platform 200 via its own external thread, or it can be fixed to the second platform 200 by other methods.

[0027] The first rack 512 and the second rack 522 are respectively provided with first rack 512 fixing members and second rack 522 fixing members at both ends. The first rack 512 fixing member is fixed to the first platform 100, and the second rack 522 fixing member is connected to the first spring fixing member 310, thereby realizing that the two ends of the first rack 512 and the second rack 522 are respectively connected to the first platform 100 and the positive stiffness spring 300. The second rack 522 fixing member can be fixedly connected to the first spring fixing member 310 by means of fastening, welding, etc., or it can be integrally formed on the first spring fixing member 310.

[0028] The second platform 200 is fixed with a guide rod 700 that passes sequentially through the positive stiffness spring 300, the first spring fixing member 310, the second rack fixing member 522, the first rack fixing member 512, and the first platform 100. Guide holes are provided at corresponding positions of the first spring fixing member 310, the second rack fixing member 522, the first rack fixing member 512, and the first platform 100. Linear bearings that mate with the guide rod 700 are installed in the guide holes of the first rack fixing member 512 and the second rack fixing member 522 to achieve a guiding effect on the first platform 100, the positive stiffness spring 300, the first spring fixing member 310, the second rack fixing member 522, the first rack fixing member 512, and the first platform 100 in the direction perpendicular to the first platform 100 / second platform 200. The guide rod 700 can be fixed to the second platform 200 by the second spring fixing member 320. The side of the second spring fixing member 320 facing away from the second platform 200 is provided with a blind hole, and the fixed end of the guide rod 700 is installed in the blind hole.

[0029] The negative stiffness spring 400 has a third spring fixing member 410 and a fourth spring fixing member 420 at its two ends, respectively. One end face of the third spring fixing member 410 is fixedly connected to the negative stiffness spring 400, and the other end has a through hole in which a first bearing that mates with the first drive shaft 610 is installed. The fourth spring fixing member 420 is a spring fixing assembly that is axially adjustable for the negative stiffness spring 400. The spring fixing assembly includes a first connecting member 421 and a second connecting member 422. One end of the first connecting member 421 is fixedly connected to the negative stiffness spring 400, and the other end has an internal thread. One end of the second connecting member 422 has an external thread, and the other end has a through hole in which a first bearing that mates with the second drive shaft 620 is installed. The internal thread of the first connecting member 421 mates with the external thread of the second connecting member 422. Adjusting the mating length allows adjustment of the extension / retraction of the spring fixing assembly, thereby adjusting the pre-compression or pre-tension of the negative stiffness spring 400. In addition, the third spring fixing member 410 can also be configured as a spring fixing assembly that is axially adjustable in the negative stiffness spring 400.

[0030] The first drive shaft 610 is connected to the shaft of the first gear 511 via an eccentric disk 630. The eccentric disk 630 has a central hole 631 and an eccentric hole 632. The shaft of the first gear 511 is connected to the central hole 631, and the first drive shaft 610 is fixedly connected to the eccentric hole 632. The central hole 631 is a spline hole, and the shaft of the first gear 511 has a spline that mates with it, thereby achieving circumferential positioning of the shaft of the first gear 511 and the eccentric disk 630. The eccentric hole 632 is an elongated hole, with its centerline passing through the center of the central hole 631. The first drive shaft 610 is adjustablely connected to the eccentric disk 630 via fasteners that engage with the elongated hole, allowing adjustment of the relative position of the first drive shaft 610 and the shaft of the first gear 511. Correspondingly, the second drive shaft 620 is connected to the shaft of the second gear 521 via another eccentric disk 630.

[0031] The shafts of the first gear 511 and the second gear 521 (collectively referred to as gear shafts 530) are both mounted on the second platform 200 via height-adjustable gear mounting seats. This allows for adjustment of the relative height between the first gear 511 and the second gear 521 (collectively referred to as gears) and the second platform 200 before fastening. The gear mounting seat includes a rod-shaped first support 541 and a cylindrical second support 542. The second support 542 is fitted over the first support 541, and its side wall has threaded holes for fasteners that abut against the side of the first support 541. Before tightening the fasteners, the relative height between the gears and the second platform 200 can be adjusted by adjusting the relative positions of the first support 541 and the second support 542. The gear shaft 530 is mounted on the free end of the first support 541 (the end furthest from the second support 542), and the free end of the second support 542 (the end furthest from the first support 541) is fixed to the second platform 200.

[0032] A bearing housing is installed at the free end of the first support 541. The bearing housing includes a bearing base 551 fixed to the free end of the first support 541, a bearing top cover 552 covering the top of the bearing base 551, and bearing end covers 553 covering both sides of the bearing base 551 and the bearing top cover 552. Two second bearings 554 that mate with the gear shaft 530 are installed in the bearing housing, and a first sleeve 555 is coaxially arranged between the two second bearings 554. The first sleeve 555, the two second bearings 554, and the two bearing end covers 553 are all sleeved on the outside of the gear shaft 530. The outer side of the second bearing 554 abuts against the bearing end cover 553, and the inner side abuts against the first sleeve 555 to achieve axial positioning. The gear is sleeved on the part of the gear shaft 530 that extends out of the bearing seat. The side of the gear facing the second bearing 554 can abut against the second sleeve 556 sleeved on the gear shaft 530 and located between the gear and the second bearing 554, or abut against the shoulder provided on the gear shaft 530. The end of the gear shaft 530 is provided with an external thread for connecting fasteners. The side of the gear facing away from the second bearing 554 can abut against the fasteners, thereby achieving axial positioning of the gear. The gear and the gear shaft 530 are connected by a key to achieve circumferential positioning.

[0033] In the aforementioned multi-stage vibration isolation device, the vibration generated by the vibration source is transmitted to the first platform 100 through the second platform 200. The object to be isolated is placed on the first platform 100. The purpose of this device is to isolate the vibration input to the second platform 200 and reduce the vibration of the first platform 100. After debugging, the device achieves good vibration isolation effect when a suitable mass (effective load) is placed on the first platform 100, and the device can support up to N effective loads. Furthermore, by adjusting the relative positions of the first support 541 and the second support 542, the dimensionless bearing capacity-displacement multi-platform curve of the vibration isolation device can be arbitrarily customized, enabling effective vibration isolation of any load within the bearing range.

[0034] When a certain effective load is applied to the first platform 100, the positive stiffness spring 300 will be compressed as the effective load is applied, and a certain amount of compression will be generated. At this time, the device is in a static equilibrium state. As the effective load is applied, the rack moves downward. Due to the meshing relationship between the rack and the gear, the movement of the rack drives the gear to rotate. The rotation of the gear causes the gear shaft 530 to rotate, which in turn drives the eccentric disk 630 to rotate. At this time, the first drive shaft 610 and the second drive shaft 620 rotate around the gear shaft 530. As a result, the center distance between the two first drive shafts 610 and the second drive shaft 620 on the same side of the device changes. This change in center distance causes a change in the length of the negative stiffness spring 400. Since the first platform 100 is subjected to a certain effective load supported by the device, when in static equilibrium, the four axes of the first drive shaft 610, the second drive shaft 620, and the two gear shafts 530 are connected by a horizontal line. Through design, the negative stiffness spring 400 can be made to have a certain amount of tension or compression in static equilibrium. At this time, the device can work normally and has vibration isolation capability. Its vibration isolation principle is mainly to connect the positive stiffness element (positive stiffness spring 300) and the negative stiffness mechanism (assembled from components such as rack, gear, and negative stiffness spring 400) in parallel, so that the dynamic stiffness in the working range is zero, while maintaining a high static load-bearing capacity.

[0035] The negative stiffness mechanism in this device comprises numerous components, with core components mainly including a rack, gears, and a negative stiffness spring 400. In static equilibrium, the lines connecting the four axes of the first drive shaft 610, the second drive shaft 620, and the two gear shafts 530 form a horizontal line. When the rack moves downwards, its motion is active, causing the two gears on the same side to rotate in opposite directions. At this point, the four axes of the first drive shaft 610, the second drive shaft 620, and the two gear shafts 530 are no longer collinear. This results in a non-zero angle between the line connecting the axes of the first drive shaft 610 and the gear shaft 530 on the same side and the horizontal line. Similarly, the line connecting the axes of the second drive shaft 620 and the gear shaft 530 on the same side also forms a non-zero angle with the horizontal line. The center distance between the first drive shaft 610 and the second drive shaft 620 is determined during installation. Since the negative stiffness spring 400 has a certain amount of tension or compression in the equilibrium state, when the angle between the line connecting the first drive shaft 610 and the second drive shaft 620 to the axis of the gear shaft 530 and the horizontal line is not zero, the negative stiffness spring 400 will drive the two gears on the same side to rotate in opposite directions. At this time, the opposite rotation of the two gears on the same side becomes the active motion, which will further drive the rack to move downward, causing the entire negative stiffness mechanism to be unable to return to the initial equilibrium state. This is also the essential characteristic of the negative stiffness mechanism.

[0036] After the device is debugged, a certain effective load is loaded on the first platform 100. When the second platform 200 vibrates due to the vibration source, the first platform 100 and the second platform 200 will have relative motion. When the first platform 100 moves downward relative to the second platform 200, the rack will also have downward relative motion. The positive stiffness spring 300 is further compressed and provides an upward force to the rack. At this time, the two gears on the same side of the device will rotate in opposite directions. The balance state of the negative stiffness mechanism is broken. The negative stiffness spring 400 will further drive the gear to rotate. The torque applied to the gear by the negative stiffness spring 400 can be converted into a downward force on the rack through the meshing of the gear and rack. Within the effective range, the resultant force (restoring force) of the rack is stable and close to zero, which means that the dynamic stiffness of the device approaches zero within the effective range. This can effectively isolate the vibration of the second platform 200 and reduce the impact of the vibration of the second platform 200 on the object on the first platform 100.

[0037] After the device is debugged, any load within the bearing range is applied to the first platform 100. If the applied load is the effective load supported by the device after debugging, the four axes of the first drive shaft 610, the second drive shaft 620, and the two gear shafts 530 are collinear. The angle between the line connecting the axis of the first drive shaft 610 and the gear shaft 530 on the same side and the horizontal line is zero. The angle between the line connecting the axis of the second drive shaft 620 and the gear shaft 530 on the same side and the horizontal line is also zero. As in the above embodiment, without any adjustment, it has a good vibration isolation effect. If the applied load is not the effective load supported by the device after commissioning, the four axes of the first drive shaft 610, the second drive shaft 620, and the two gear shafts 530 will not be collinear. The line connecting the axis of the first drive shaft 610 and the gear shaft 530 on the same side will form a non-zero angle with the horizontal line, and the same non-zero angle will also form between the line connecting the axis of the second drive shaft 620 and the gear shaft 530 on the same side and the horizontal line. This state corresponds to... Figure 7 The black dot A on the dimensionless load-displacement curve before and after adjustment of the device shown indicates that the dynamic stiffness is relatively large at this point. The four axes of the first drive shaft 610, the second drive shaft 620, and the two gear shafts 530 can be ensured to be collinear by adjusting the relative positions of the first support 541 and the second support 542. The adjusted state corresponds to... Figure 7 The red dot B on the dimensionless bearing capacity-displacement curve before and after adjustment of the device shown in the figure clearly shows that the dynamic stiffness at point B is small or even close to zero. After one adjustment, it has a good vibration isolation effect, just like the above embodiment.

[0038] Currently, common quasi-zero stiffness vibration isolation mechanisms typically have only one effective working range. This device, however, utilizes a rack and pinion transmission with a negative stiffness spring (400) as the negative stiffness elastic element. As the rack moves downwards, the gear rotates. New quasi-zero stiffness regions appear whenever the gear rotates to an integer multiple of 180°. The loaded mass and the downward movement of the rack are completely interchangeable. This means that the quasi-zero stiffness region of the vibration isolation device will cyclically reappear every time the rack moves downwards by half the circumference of the gear's pitch circle. Figure 5 The figure shows the dimensionless bearing capacity-displacement curve of the device. From this curve, it can be observed that the platform segment appears continuously and cyclically. Figure 6The figure shows the dimensionless stiffness-displacement curve of the device. From the curve, it can be observed that the quasi-zero stiffness range continuously cyclically appears, indicating that the device can effectively isolate vibrations under various loads. Furthermore, after the vibration isolation device is assembled and debugged, the effective load of the device can be easily adjusted by changing the relative positions of the first support 541 and the second support 542 without replacing any parts. This allows for arbitrary customization of the dimensionless load-displacement multi-platform curve of the vibration isolation device, such as... Figure 7 The figure shows the dimensionless bearing capacity-displacement curves before and after the device is adjusted. It can be observed from the dimensionless bearing capacity-displacement curves before and after the device is adjusted that the height of the platform can be continuously changed within the bearing range by adjustment, which can effectively isolate any load within the bearing range.

[0039] Obviously, the above embodiments of this solution are merely examples for clearly illustrating this solution, and are not intended to limit the implementation of this solution. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this solution should be included within the scope of protection of the claims of this solution.

Claims

1. A multi-stage vibration isolation device, comprising a first platform and a second platform parallel to each other, and a positive stiffness spring and a negative stiffness spring disposed between the first platform and the second platform, wherein the positive stiffness spring is perpendicular to the first platform / second platform, and the negative stiffness spring is parallel to the first platform / second platform; characterized in that, The positive stiffness spring and the negative stiffness spring are connected in parallel to the second gear and rack mechanism through a symmetrically arranged first gear and rack mechanism. The first gear and rack mechanism includes a first gear and a first rack that mesh with each other, and the second gear and rack mechanism includes a second gear and a second rack that mesh with each other. The tooth surfaces of the first rack and the second rack are arranged opposite to each other or back to back, and each rack is fixedly connected at one end to the first platform and at the other end to one end of the positive stiffness spring. The other end of the positive stiffness spring is connected to the second platform. The shafts of the first gear and the second gear are both mounted on the second platform. The shaft of the first gear is driven by a first drive shaft parallel to it, and the shaft of the second gear is driven by a second drive shaft parallel to it. The two ends of the negative stiffness spring are driven by the first drive shaft and the second drive shaft, respectively. The first drive shaft is connected to the shaft of the first gear via an eccentric disk, and the second drive shaft is connected to the shaft of the second gear via another eccentric disk. The eccentric disk has a central hole and an eccentric hole. The central hole drives the shafts of the first gear and the second gear. The eccentric hole is an elongated hole, and the center line of the elongated hole passes through the center of the central hole along its length. The first drive shaft and the second drive shaft are fixedly connected to the corresponding elongated holes by fasteners. The central hole is a spline hole, and the shafts of the first gear and the second gear are provided with splines that mate with it. The first drive shaft is connected to one end of the negative stiffness spring via a spring fixing member, and the second drive shaft is connected to the other end of the negative stiffness spring via another spring fixing member; one end of the spring fixing member is fixedly connected to the negative stiffness spring, and the other end is provided with a through hole, in which a first bearing is installed, and the first drive shaft and the second drive shaft are engaged with the corresponding first bearing.

2. The multi-stage vibration isolation device according to claim 1, characterized in that, At least one end of the negative stiffness spring is connected to the first drive shaft and / or the second drive shaft via a spring fixing assembly that is axially adjustable.

3. The multi-stage vibration isolation device according to claim 2, characterized in that, The spring fixing assembly includes a first connector and a second connector. One end of the first connector is fixedly connected to a negative stiffness spring, and the other end is provided with an internal thread. One end of the second connector is provided with an external thread, and the other end is drively connected to a first drive shaft and / or a second drive shaft. The internal thread of the first connector mates with the external thread of the second connector; or The spring fixing assembly includes a first connector and a second connector. One end of the first connector is fixedly connected to a negative stiffness spring, and the other end is provided with an external thread. One end of the second connector is provided with an internal thread, and the other end is connected to a first drive shaft and / or a second drive shaft. The external thread of the first connector mates with the internal thread of the second connector.

4. The multi-stage vibration isolation device according to claim 1, characterized in that, The shafts of both the first gear and the second gear are mounted on the second platform via height-adjustable gear mounting brackets.

5. The multi-stage vibration isolation device according to claim 4, characterized in that, The gear fixing seat includes a rod-shaped first support and a cylindrical second support. The second support is sleeved outside the first support. The side wall of the second support is provided with a threaded hole, and the threaded hole is connected to a fastener that abuts against the side of the first support. The shafts of the first gear and the second gear are mounted on the free end of the first support, and the free end of the second support is fixed to the second platform.

6. The multi-stage vibration isolation device according to any one of claims 1 to 5, characterized in that, The first platform is provided with a guide hole, and the second platform is fixed with a guide rod that mates with the guide hole.

7. The multi-stage vibration isolation device according to claim 6, characterized in that, One end of the first rack and the second rack are fixed to the first platform by the first rack fixing member, and the other end is fixedly connected to the positive stiffness spring by the second rack fixing member. Both the first rack fixing member and the second rack fixing member are provided with guide holes that cooperate with the guide rod.

8. The multi-stage vibration isolation device according to claim 7, characterized in that, Linear bearings that mate with the guide rod are installed in the guide holes of the first and second rack fixing members.

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