CN-122014777-A - Quasi-zero stiffness vibration isolator with adjustable negative stiffness and vibration isolation method

CN122014777ACN 122014777 ACN122014777 ACN 122014777ACN-122014777-A

Abstract

The invention discloses a quasi-zero stiffness vibration isolator with adjustable negative stiffness, which comprises a base, a guide mechanism, a central shaft, a negative stiffness mechanism, a positive stiffness mechanism, a vibration isolation box body, an angle adjusting mechanism and a load platform, wherein the base is horizontally arranged, the lower end of the central shaft is arranged in the base through the guide mechanism at the lower part, the positive stiffness mechanism and the negative stiffness mechanism are assembled on the central shaft from bottom to top and axially move along the central shaft, the positive stiffness mechanism is arranged in the vibration isolation box body, the angle adjusting mechanism is arranged outside the negative stiffness mechanism, the output end of the angle adjusting mechanism is connected with the negative stiffness mechanism, and the upper end of the central shaft is connected with the bottom of the load platform. The invention also discloses a vibration isolation method. The vibration isolator has the beneficial effects of simple overall structural design, convenience in assembly and maintenance, effective reduction of processing, manufacturing and use costs, wide negative stiffness adjusting range, capability of adapting to different load masses, capability of adjusting the vibration isolator to or approaching to an ideal quasi-zero stiffness state and wide suitability.

Inventors

MA ZHAOZHAO
Dong Zhangbing
ZHOU RUIPING

Assignees

武汉理工大学

Dates

Publication Date: 20260512
Application Date: 20260325

Claims (10)

1. The quasi-zero stiffness vibration isolator is characterized by comprising a base, a guide mechanism, a central shaft, a negative stiffness mechanism, a positive stiffness mechanism, a vibration isolation box body, an angle adjusting mechanism and a load platform; the lower end of the central shaft is arranged in the base through a lower guide mechanism; The positive stiffness mechanism and the negative stiffness mechanism are assembled on the central shaft from bottom to top and axially move along the central shaft, the positive stiffness mechanism is arranged in the vibration isolation box body, the angle adjusting mechanism is arranged outside the negative stiffness mechanism, and the output end of the angle adjusting mechanism is connected with the negative stiffness mechanism; the upper end of the central shaft extends out from the top of the negative rigidity mechanism, passes through the guide mechanism at the upper part and is connected with the bottom of the load platform.
2. The adjustable negative stiffness quasi-zero stiffness vibration isolator of claim 1, wherein the negative stiffness mechanism comprises an inner tile-shaped permanent magnet, an outer tile-shaped permanent magnet, two sets of inner ring-shaped permanent magnets, two sets of outer ring-shaped permanent magnets, and a magnet housing; The inner tile-shaped permanent magnet and the outer tile-shaped permanent magnet are coaxially arranged, the inner tile-shaped permanent magnet and inner ring-shaped permanent magnets on the upper side and the lower side of the inner tile-shaped permanent magnet are assembled on a central shaft, the upper end and the lower end of the inner ring-shaped permanent magnet are respectively pressed by a fixing ring; The output end of the angle adjusting mechanism is connected with the input end of the magnet housing, the angle adjusting mechanism drives the magnet housing to rotate, and the outer tile-shaped permanent magnet and the outer ring-shaped permanent magnet which are positioned in the magnet housing synchronously rotate relative to the inner tile-shaped permanent magnet and the inner ring-shaped permanent magnet.
3. The negative stiffness adjustable quasi-zero stiffness vibration isolator according to claim 2, wherein the inner tile-shaped permanent magnets and the outer tile-shaped permanent magnets are each a magnet assembly and magnetized in the radial direction, and the magnet assemblies are formed by circumferentially spacing even tile-shaped magnet blocks.
4. The quasi-zero stiffness vibration isolator with adjustable negative stiffness according to claim 3, wherein in the inner tile-shaped permanent magnet, the upper end face and the lower end face of each tile-shaped magnet are respectively pressed with the inner ring-shaped permanent magnet assembled on the central shaft and axially move along with the central shaft; In the outer-layer tile-shaped magnetic blocks, the upper end face of each tile-shaped magnetic block is bonded and pressed with the lower end face of the upper outer-ring-shaped permanent magnet, the lower end face of each tile-shaped magnetic block is bonded with the upper end face of the lower outer-ring-shaped permanent magnet, the outer part of each tile-shaped magnetic block is pressed and fixed with a magnet shell, and the magnetizing directions of two adjacent tile-shaped magnetic blocks are opposite.
5. The negative stiffness adjustable quasi-zero stiffness vibration isolator according to claim 4, wherein the angle adjustment mechanism comprises a worm and a worm gear, the worm is vertically arranged, the worm is meshed with the worm gear, the worm gear is fixed on the periphery of the magnet housing, and the worm rotates to drive the worm gear to rotate, and then drive the magnet housing and the outer tile-shaped permanent magnet and the outer ring-shaped permanent magnet inside the magnet housing to rotate relative to the inner tile-shaped permanent magnet and the inner ring-shaped permanent magnet.
6. The negative stiffness adjustable quasi-zero stiffness vibration isolator of claim 5 wherein the guide mechanism is a linear bearing and the central axis is adapted to the inner race of the linear bearing.
7. The negative-rigidity-adjustable quasi-zero-rigidity vibration isolator according to claim 6, wherein the vibration isolator comprises an upper box body, a middle box body and a lower box body which are sequentially connected, a guide mechanism positioned at the upper part is arranged in the upper box body, worm wheels of the negative-rigidity mechanism and the angle adjusting mechanism are arranged in the middle box body, a worm of the angle adjusting mechanism is arranged outside the middle box body, a window is formed in the middle box body and used for being in transmission connection with the worm wheels, the magnet shell is rotatably connected with the upper end of the lower box body, and the magnet shell rotates relative to the lower box body.
8. The negative stiffness adjustable quasi-zero stiffness vibration isolator according to claim 7, wherein the positive stiffness mechanism comprises a linear spiral spring sleeved outside the central shaft, the upper end of the linear spiral spring is in contact with a fixed ring at the lower part of the inner annular permanent magnet, and the lower end of the linear spiral spring is in contact with the upper port of the base.
9. A method of vibration isolation based on the quasi-zero stiffness vibration isolator of claim 8, comprising: s1, testing and calibrating, namely testing magnetic force-displacement curve families of the negative stiffness mechanism under different rotation angles, and matching and adapting positive stiffness springs for different negative stiffness to finish initial parameter calibration; S2, driving the negative stiffness mechanism to rotate through the angle adjusting mechanism according to the actual load capacity, adjusting the negative stiffness, and confirming that the negative stiffness value is offset with the positive stiffness of the positive stiffness mechanism, wherein the system achieves a quasi-zero stiffness state; And S3, load adaptation and vibration isolation, namely stably placing a load to be isolated on a load platform, enabling a central shaft to be under the action of load gravity to drive the inner tile-shaped permanent magnet and the inner ring-shaped permanent magnet to vertically displace downwards, enabling a fixed ring at the lower part of the inner ring-shaped permanent magnet to squeeze the positive stiffness mechanism to enable the positive stiffness mechanism to bear the load, and if the load changes, repeating the negative stiffness adjusting process of the step S2 to change the negative stiffness value, ensuring that the negative stiffness and the positive stiffness are always matched, and realizing quasi-zero stiffness adaptation under different loads.
10. The vibration isolation method of claim 9, wherein the specific process of S2 is as follows: S201, load detection, namely acquiring the actual load capacity on a load platform, and determining a required target negative stiffness value and a rotation angle of a corresponding angle adjusting mechanism; S202, rotating a magnet, namely rotating a worm arranged outside the middle box body, wherein the worm is meshed with a worm wheel fixed on the periphery of the magnet shell, and the worm rotates to drive the worm wheel to synchronously rotate so as to drive the magnet shell to rotate around a central shaft; S203, negative rigidity adjustment, namely, when the inner tile-shaped permanent magnet and the outer tile-shaped permanent magnet relatively rotate, the space distribution of magnetic force lines is changed due to the fact that magnetizing directions of adjacent tile-shaped magnetic blocks are opposite, and then the gradient of vertical magnetic force along with displacement change is changed, namely, a negative rigidity value; and S204, after the adjustment is completed, confirming that the negative stiffness value is counteracted with the positive stiffness of the positive stiffness mechanism, and enabling the system to reach a quasi-zero stiffness state.

Description

Quasi-zero stiffness vibration isolator with adjustable negative stiffness and vibration isolation method Technical Field The invention relates to the technical field of vibration control and isolation, in particular to a quasi-zero stiffness vibration isolator with adjustable negative stiffness and a vibration isolation method. Background The quasi-zero stiffness vibration isolator realizes extremely low dynamic stiffness near a static balance position through parallel connection of positive and negative stiffness mechanisms, so that the natural frequency of a system can be reduced to an extremely low level, and effective isolation of low-frequency and even ultra-low-frequency vibration is realized. However, the negative stiffness characteristics of conventional quasi-zero stiffness vibration isolators are typically provided by geometric non-linear structures (e.g., buckling beams, plates) or fixed parameter magnetic mechanisms, the force-displacement relationship of which is determined after design, which results in a system that achieves the desired "high static stiffness-low dynamic stiffness" characteristics only at the rated load of the design. When the actual load mass changes, the static balance position of the system can deviate, the positive stiffness mechanism and the negative stiffness mechanism can not be perfectly offset at the deviating positions, so that dynamic stiffness is rapidly increased, and the vibration isolation performance is remarkably deteriorated, which is also a main bottleneck for limiting the engineering application of the traditional quasi-zero stiffness vibration isolator. To solve the above problems, the prior art has attempted various methods. For example, an active or semi-active control strategy is adopted, and system parameters are adjusted in real time through a sensor, a controller and an actuator, but the method is complex in structure, high in cost and limited in reliability under severe environments. For another example, with mechanical adjustment, the negative stiffness is adjusted by changing the spacing between the permanent magnets, but the adjustment range is limited and the continuous adjustment mechanism is complex. Therefore, the quasi-zero stiffness vibration isolator which is relatively simple in structure, convenient to adjust and capable of being self-adaptively or manually adjusted in a wide load range to achieve positive and negative stiffness matching is developed, and has important theoretical value and engineering significance. Disclosure of Invention The invention aims to provide a quasi-zero stiffness vibration isolator with adjustable negative stiffness and a vibration isolation method, aiming at overcoming the defects of the prior art, and solving the problems of complex structure and limited adjusting range in the prior art. The invention adopts the technical scheme that the quasi-zero stiffness vibration isolator with adjustable negative stiffness comprises a base, a guide mechanism, a central shaft, a negative stiffness mechanism, a positive stiffness mechanism, a vibration isolation box body, an angle adjusting mechanism and a load platform; the lower end of the central shaft is arranged in the base through a lower guide mechanism; The positive stiffness mechanism and the negative stiffness mechanism are assembled on the central shaft from bottom to top and axially move along the central shaft, the positive stiffness mechanism is arranged in the vibration isolation box body, the angle adjusting mechanism is arranged outside the negative stiffness mechanism, and the output end of the angle adjusting mechanism is connected with the negative stiffness mechanism; the upper end of the central shaft extends out from the top of the negative rigidity mechanism, passes through the guide mechanism at the upper part and is connected with the bottom of the load platform. According to the scheme, the negative stiffness mechanism comprises an inner tile-shaped permanent magnet, an outer tile-shaped permanent magnet, two groups of inner ring-shaped permanent magnets, two groups of outer ring-shaped permanent magnets and a magnet housing; The inner tile-shaped permanent magnet and the outer tile-shaped permanent magnet are coaxially arranged, the inner tile-shaped permanent magnet and inner ring-shaped permanent magnets on the upper side and the lower side of the inner tile-shaped permanent magnet are assembled on a central shaft, the upper end and the lower end of the inner ring-shaped permanent magnet are respectively pressed by a fixing ring; The output end of the angle adjusting mechanism is connected with the input end of the magnet housing, the angle adjusting mechanism drives the magnet housing to rotate, and the outer tile-shaped permanent magnet and the outer ring-shaped permanent magnet which are positioned in the magnet housing synchronously rotate relative to the inner tile-shaped permanent magnet and the inner ring-shaped permanent magnet. Ac